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3ae426ff96d68e42f520613bac790399978c75d5 | 27a31d06bcfc7c5d379fd04a08a9f5ed3f5302d4 | /src/Init/Data/List/BasicAux.lean | 730da18806f0f7bee7c59346d735aca9e1e3558e | [
"Apache-2.0",
"LLVM-exception",
"NCSA",
"LGPL-3.0-only",
"LicenseRef-scancode-inner-net-2.0",
"BSD-3-Clause",
"LGPL-2.0-or-later",
"Spencer-94",
"LGPL-2.1-or-later",
"HPND",
"LicenseRef-scancode-pcre",
"ISC",
"LGPL-2.1-only",
"LicenseRef-scancode-other-permissive",
"SunPro",
"CMU-Mach"... | permissive | joehendrix/lean4 | 0d1486945f7ca9fe225070374338f4f7e74bab03 | 1221bdd3c7d5395baa451ce8fdd2c2f8a00cbc8f | refs/heads/master | 1,640,573,727,861 | 1,639,662,710,000 | 1,639,665,515,000 | 198,893,504 | 0 | 0 | Apache-2.0 | 1,564,084,645,000 | 1,564,084,644,000 | null | UTF-8 | Lean | false | false | 2,260 | lean | /-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
-/
prelude
import Init.Data.List.Basic
import Init.Util
universe u
namespace List
/- The following functions can't be defined at `Init.Data.List.Basic`, because they depend on `Init.Util`,
and `Init.Util` depends on `Init.Data.List.Basic`. -/
def get! [Inhabited α] : Nat → List α → α
| 0, a::as => a
| n+1, a::as => get! n as
| _, _ => panic! "invalid index"
def get? : Nat → List α → Option α
| 0, a::as => some a
| n+1, a::as => get? n as
| _, _ => none
def getD (idx : Nat) (as : List α) (a₀ : α) : α :=
(as.get? idx).getD a₀
def head! [Inhabited α] : List α → α
| [] => panic! "empty list"
| a::_ => a
def head? : List α → Option α
| [] => none
| a::_ => some a
def headD : List α → α → α
| [], a₀ => a₀
| a::_, _ => a
def head : (as : List α) → as ≠ [] → α
| a::_, _ => a
def tail! : List α → List α
| [] => panic! "empty list"
| a::as => as
def tail? : List α → Option (List α)
| [] => none
| a::as => some as
def tailD : List α → List α → List α
| [], as₀ => as₀
| a::as, _ => as
def getLast : ∀ (as : List α), as ≠ [] → α
| [], h => absurd rfl h
| [a], h => a
| a::b::as, h => getLast (b::as) (fun h => List.noConfusion h)
def getLast! [Inhabited α] : List α → α
| [] => panic! "empty list"
| a::as => getLast (a::as) (fun h => List.noConfusion h)
def getLast? : List α → Option α
| [] => none
| a::as => some (getLast (a::as) (fun h => List.noConfusion h))
def getLastD : List α → α → α
| [], a₀ => a₀
| a::as, _ => getLast (a::as) (fun h => List.noConfusion h)
def rotateLeft (xs : List α) (n : Nat := 1) : List α :=
let len := xs.length
if len ≤ 1 then
xs
else
let n := n % len
let b := xs.take n
let e := xs.drop n
e ++ b
def rotateRight (xs : List α) (n : Nat := 1) : List α :=
let len := xs.length
if len ≤ 1 then
xs
else
let n := len - n % len
let b := xs.take n
let e := xs.drop n
e ++ b
end List
|
61c62c0f5648f54b24ee4f41903dd77e2addf46b | 4727251e0cd73359b15b664c3170e5d754078599 | /src/analysis/asymptotics/asymptotics.lean | b3c1450f08ade006b354f2f9f4be632290133e21 | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 65,684 | lean | /-
Copyright (c) 2019 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Yury Kudryashov
-/
import analysis.normed_space.basic
import topology.algebra.order.liminf_limsup
import topology.local_homeomorph
/-!
# Asymptotics
We introduce these relations:
* `is_O_with c f g l` : "f is big O of g along l with constant c";
* `is_O f g l` : "f is big O of g along l";
* `is_o f g l` : "f is little o of g along l".
Here `l` is any filter on the domain of `f` and `g`, which are assumed to be the same. The codomains
of `f` and `g` do not need to be the same; all that is needed that there is a norm associated with
these types, and it is the norm that is compared asymptotically.
The relation `is_O_with c` is introduced to factor out common algebraic arguments in the proofs of
similar properties of `is_O` and `is_o`. Usually proofs outside of this file should use `is_O`
instead.
Often the ranges of `f` and `g` will be the real numbers, in which case the norm is the absolute
value. In general, we have
`is_O f g l ↔ is_O (λ x, ∥f x∥) (λ x, ∥g x∥) l`,
and similarly for `is_o`. But our setup allows us to use the notions e.g. with functions
to the integers, rationals, complex numbers, or any normed vector space without mentioning the
norm explicitly.
If `f` and `g` are functions to a normed field like the reals or complex numbers and `g` is always
nonzero, we have
`is_o f g l ↔ tendsto (λ x, f x / (g x)) l (𝓝 0)`.
In fact, the right-to-left direction holds without the hypothesis on `g`, and in the other direction
it suffices to assume that `f` is zero wherever `g` is. (This generalization is useful in defining
the Fréchet derivative.)
-/
open filter set
open_locale topological_space big_operators classical filter nnreal
namespace asymptotics
variables {α : Type*} {β : Type*} {E : Type*} {F : Type*} {G : Type*}
{E' : Type*} {F' : Type*} {G' : Type*}
{E'' : Type*} {F'' : Type*} {G'' : Type*}
{R : Type*} {R' : Type*} {𝕜 : Type*} {𝕜' : Type*}
variables [has_norm E] [has_norm F] [has_norm G]
variables [semi_normed_group E'] [semi_normed_group F'] [semi_normed_group G']
variables [normed_group E''] [normed_group F''] [normed_group G'']
variables [semi_normed_ring R] [semi_normed_ring R']
variables [normed_field 𝕜] [normed_field 𝕜']
variables {c c' : ℝ} {f : α → E} {g : α → F} {k : α → G}
variables {f' : α → E'} {g' : α → F'} {k' : α → G'}
variables {f'' : α → E''} {g'' : α → F''} {k'' : α → G''}
variables {l l' : filter α}
section defs
/-! ### Definitions -/
/-- This version of the Landau notation `is_O_with C f g l` where `f` and `g` are two functions on
a type `α` and `l` is a filter on `α`, means that eventually for `l`, `∥f∥` is bounded by `C * ∥g∥`.
In other words, `∥f∥ / ∥g∥` is eventually bounded by `C`, modulo division by zero issues that are
avoided by this definition. Probably you want to use `is_O` instead of this relation. -/
@[irreducible]
def is_O_with (c : ℝ) (f : α → E) (g : α → F) (l : filter α) : Prop :=
∀ᶠ x in l, ∥ f x ∥ ≤ c * ∥ g x ∥
/-- Definition of `is_O_with`. We record it in a lemma as we will set `is_O_with` to be irreducible
at the end of this file. -/
lemma is_O_with_iff {c : ℝ} {f : α → E} {g : α → F} {l : filter α} :
is_O_with c f g l ↔ ∀ᶠ x in l, ∥ f x ∥ ≤ c * ∥ g x ∥ := by rw is_O_with
alias is_O_with_iff ↔ asymptotics.is_O_with.bound asymptotics.is_O_with.of_bound
/-- The Landau notation `is_O f g l` where `f` and `g` are two functions on a type `α` and `l` is
a filter on `α`, means that eventually for `l`, `∥f∥` is bounded by a constant multiple of `∥g∥`.
In other words, `∥f∥ / ∥g∥` is eventually bounded, modulo division by zero issues that are avoided
by this definition. -/
@[irreducible]
def is_O (f : α → E) (g : α → F) (l : filter α) : Prop := ∃ c : ℝ, is_O_with c f g l
/-- Definition of `is_O` in terms of `is_O_with`. We record it in a lemma as we will set
`is_O` to be irreducible at the end of this file. -/
lemma is_O_iff_is_O_with {f : α → E} {g : α → F} {l : filter α} :
is_O f g l ↔ ∃ c : ℝ, is_O_with c f g l := by rw is_O
/-- Definition of `is_O` in terms of filters. We record it in a lemma as we will set
`is_O` to be irreducible at the end of this file. -/
lemma is_O_iff {f : α → E} {g : α → F} {l : filter α} :
is_O f g l ↔ ∃ c : ℝ, ∀ᶠ x in l, ∥ f x ∥ ≤ c * ∥ g x ∥ := by simp [is_O, is_O_with]
lemma is_O.of_bound (c : ℝ) {f : α → E} {g : α → F} {l : filter α}
(h : ∀ᶠ x in l, ∥ f x ∥ ≤ c * ∥ g x ∥) : is_O f g l := is_O_iff.2 ⟨c, h⟩
lemma is_O.bound {f : α → E} {g : α → F} {l : filter α} :
is_O f g l → ∃ c : ℝ, ∀ᶠ x in l, ∥ f x ∥ ≤ c * ∥ g x ∥ := is_O_iff.1
/-- The Landau notation `is_o f g l` where `f` and `g` are two functions on a type `α` and `l` is
a filter on `α`, means that eventually for `l`, `∥f∥` is bounded by an arbitrarily small constant
multiple of `∥g∥`. In other words, `∥f∥ / ∥g∥` tends to `0` along `l`, modulo division by zero
issues that are avoided by this definition. -/
@[irreducible]
def is_o (f : α → E) (g : α → F) (l : filter α) : Prop := ∀ ⦃c : ℝ⦄, 0 < c → is_O_with c f g l
/-- Definition of `is_o` in terms of `is_O_with`. We record it in a lemma as we will set
`is_o` to be irreducible at the end of this file. -/
lemma is_o_iff_forall_is_O_with {f : α → E} {g : α → F} {l : filter α} :
is_o f g l ↔ ∀ ⦃c : ℝ⦄, 0 < c → is_O_with c f g l := by rw is_o
alias is_o_iff_forall_is_O_with ↔ asymptotics.is_o.forall_is_O_with asymptotics.is_o.of_is_O_with
/-- Definition of `is_o` in terms of filters. We record it in a lemma as we will set
`is_o` to be irreducible at the end of this file. -/
lemma is_o_iff {f : α → E} {g : α → F} {l : filter α} :
is_o f g l ↔ ∀ ⦃c : ℝ⦄, 0 < c → ∀ᶠ x in l, ∥ f x ∥ ≤ c * ∥ g x ∥ :=
by simp only [is_o, is_O_with]
alias is_o_iff ↔ asymptotics.is_o.bound asymptotics.is_o.of_bound
lemma is_o.def {f : α → E} {g : α → F} {l : filter α} (h : is_o f g l) {c : ℝ} (hc : 0 < c) :
∀ᶠ x in l, ∥ f x ∥ ≤ c * ∥ g x ∥ :=
is_o_iff.1 h hc
lemma is_o.def' {f : α → E} {g : α → F} {l : filter α} (h : is_o f g l) {c : ℝ} (hc : 0 < c) :
is_O_with c f g l :=
is_O_with_iff.2 $ is_o_iff.1 h hc
end defs
/-! ### Conversions -/
theorem is_O_with.is_O (h : is_O_with c f g l) : is_O f g l := by rw is_O; exact ⟨c, h⟩
theorem is_o.is_O_with (hgf : is_o f g l) : is_O_with 1 f g l := hgf.def' zero_lt_one
theorem is_o.is_O (hgf : is_o f g l) : is_O f g l := hgf.is_O_with.is_O
lemma is_O.is_O_with {f : α → E} {g : α → F} {l : filter α} :
is_O f g l → ∃ c : ℝ, is_O_with c f g l := is_O_iff_is_O_with.1
theorem is_O_with.weaken (h : is_O_with c f g' l) (hc : c ≤ c') : is_O_with c' f g' l :=
is_O_with.of_bound $ mem_of_superset h.bound $ λ x hx,
calc ∥f x∥ ≤ c * ∥g' x∥ : hx
... ≤ _ : mul_le_mul_of_nonneg_right hc (norm_nonneg _)
theorem is_O_with.exists_pos (h : is_O_with c f g' l) :
∃ c' (H : 0 < c'), is_O_with c' f g' l :=
⟨max c 1, lt_of_lt_of_le zero_lt_one (le_max_right c 1), h.weaken $ le_max_left c 1⟩
theorem is_O.exists_pos (h : is_O f g' l) : ∃ c (H : 0 < c), is_O_with c f g' l :=
let ⟨c, hc⟩ := h.is_O_with in hc.exists_pos
theorem is_O_with.exists_nonneg (h : is_O_with c f g' l) :
∃ c' (H : 0 ≤ c'), is_O_with c' f g' l :=
let ⟨c, cpos, hc⟩ := h.exists_pos in ⟨c, le_of_lt cpos, hc⟩
theorem is_O.exists_nonneg (h : is_O f g' l) :
∃ c (H : 0 ≤ c), is_O_with c f g' l :=
let ⟨c, hc⟩ := h.is_O_with in hc.exists_nonneg
/-- `f = O(g)` if and only if `is_O_with c f g` for all sufficiently large `c`. -/
lemma is_O_iff_eventually_is_O_with : is_O f g' l ↔ ∀ᶠ c in at_top, is_O_with c f g' l :=
is_O_iff_is_O_with.trans
⟨λ ⟨c, hc⟩, mem_at_top_sets.2 ⟨c, λ c' hc', hc.weaken hc'⟩, λ h, h.exists⟩
/-- `f = O(g)` if and only if `∀ᶠ x in l, ∥f x∥ ≤ c * ∥g x∥` for all sufficiently large `c`. -/
lemma is_O_iff_eventually : is_O f g' l ↔ ∀ᶠ c in at_top, ∀ᶠ x in l, ∥f x∥ ≤ c * ∥g' x∥ :=
is_O_iff_eventually_is_O_with.trans $ by simp only [is_O_with]
lemma is_O.exists_mem_basis {ι} {p : ι → Prop} {s : ι → set α} (h : is_O f g' l)
(hb : l.has_basis p s) :
∃ (c : ℝ) (hc : 0 < c) (i : ι) (hi : p i), ∀ x ∈ s i, ∥f x∥ ≤ c * ∥g' x∥ :=
flip Exists₂.imp h.exists_pos $ λ c hc h,
by simpa only [is_O_with_iff, hb.eventually_iff, exists_prop] using h
/-! ### Subsingleton -/
@[nontriviality] lemma is_o_of_subsingleton [subsingleton E'] : is_o f' g' l :=
is_o.of_bound $ λ c hc, by simp [subsingleton.elim (f' _) 0, mul_nonneg hc.le]
@[nontriviality] lemma is_O_of_subsingleton [subsingleton E'] : is_O f' g' l :=
is_o_of_subsingleton.is_O
/-! ### Congruence -/
theorem is_O_with_congr {c₁ c₂} {f₁ f₂ : α → E} {g₁ g₂ : α → F} {l : filter α}
(hc : c₁ = c₂) (hf : f₁ =ᶠ[l] f₂) (hg : g₁ =ᶠ[l] g₂) :
is_O_with c₁ f₁ g₁ l ↔ is_O_with c₂ f₂ g₂ l :=
begin
unfold is_O_with,
subst c₂,
apply filter.eventually_congr,
filter_upwards [hf, hg] with _ e₁ e₂,
rw [e₁, e₂],
end
theorem is_O_with.congr' {c₁ c₂} {f₁ f₂ : α → E} {g₁ g₂ : α → F} {l : filter α}
(hc : c₁ = c₂) (hf : f₁ =ᶠ[l] f₂) (hg : g₁ =ᶠ[l] g₂) :
is_O_with c₁ f₁ g₁ l → is_O_with c₂ f₂ g₂ l :=
(is_O_with_congr hc hf hg).mp
theorem is_O_with.congr {c₁ c₂} {f₁ f₂ : α → E} {g₁ g₂ : α → F} {l : filter α}
(hc : c₁ = c₂) (hf : ∀ x, f₁ x = f₂ x) (hg : ∀ x, g₁ x = g₂ x) :
is_O_with c₁ f₁ g₁ l → is_O_with c₂ f₂ g₂ l :=
λ h, h.congr' hc (univ_mem' hf) (univ_mem' hg)
theorem is_O_with.congr_left {f₁ f₂ : α → E} {l : filter α} (hf : ∀ x, f₁ x = f₂ x) :
is_O_with c f₁ g l → is_O_with c f₂ g l :=
is_O_with.congr rfl hf (λ _, rfl)
theorem is_O_with.congr_right {g₁ g₂ : α → F} {l : filter α} (hg : ∀ x, g₁ x = g₂ x) :
is_O_with c f g₁ l → is_O_with c f g₂ l :=
is_O_with.congr rfl (λ _, rfl) hg
theorem is_O_with.congr_const {c₁ c₂} {l : filter α} (hc : c₁ = c₂) :
is_O_with c₁ f g l → is_O_with c₂ f g l :=
is_O_with.congr hc (λ _, rfl) (λ _, rfl)
theorem is_O_congr {f₁ f₂ : α → E} {g₁ g₂ : α → F} {l : filter α}
(hf : f₁ =ᶠ[l] f₂) (hg : g₁ =ᶠ[l] g₂) :
is_O f₁ g₁ l ↔ is_O f₂ g₂ l :=
by { unfold is_O, exact exists_congr (λ c, is_O_with_congr rfl hf hg) }
theorem is_O.congr' {f₁ f₂ : α → E} {g₁ g₂ : α → F} {l : filter α}
(hf : f₁ =ᶠ[l] f₂) (hg : g₁ =ᶠ[l] g₂) :
is_O f₁ g₁ l → is_O f₂ g₂ l :=
(is_O_congr hf hg).mp
theorem is_O.congr {f₁ f₂ : α → E} {g₁ g₂ : α → F} {l : filter α}
(hf : ∀ x, f₁ x = f₂ x) (hg : ∀ x, g₁ x = g₂ x) :
is_O f₁ g₁ l → is_O f₂ g₂ l :=
λ h, h.congr' (univ_mem' hf) (univ_mem' hg)
theorem is_O.congr_left {f₁ f₂ : α → E} {l : filter α} (hf : ∀ x, f₁ x = f₂ x) :
is_O f₁ g l → is_O f₂ g l :=
is_O.congr hf (λ _, rfl)
theorem is_O.congr_right {g₁ g₂ : α → E} {l : filter α} (hg : ∀ x, g₁ x = g₂ x) :
is_O f g₁ l → is_O f g₂ l :=
is_O.congr (λ _, rfl) hg
theorem is_o_congr {f₁ f₂ : α → E} {g₁ g₂ : α → F} {l : filter α}
(hf : f₁ =ᶠ[l] f₂) (hg : g₁ =ᶠ[l] g₂) :
is_o f₁ g₁ l ↔ is_o f₂ g₂ l :=
by { unfold is_o, exact ball_congr (λ c hc, is_O_with_congr (eq.refl c) hf hg) }
theorem is_o.congr' {f₁ f₂ : α → E} {g₁ g₂ : α → F} {l : filter α}
(hf : f₁ =ᶠ[l] f₂) (hg : g₁ =ᶠ[l] g₂) :
is_o f₁ g₁ l → is_o f₂ g₂ l :=
(is_o_congr hf hg).mp
theorem is_o.congr {f₁ f₂ : α → E} {g₁ g₂ : α → F} {l : filter α}
(hf : ∀ x, f₁ x = f₂ x) (hg : ∀ x, g₁ x = g₂ x) :
is_o f₁ g₁ l → is_o f₂ g₂ l :=
λ h, h.congr' (univ_mem' hf) (univ_mem' hg)
theorem is_o.congr_left {f₁ f₂ : α → E} {l : filter α} (hf : ∀ x, f₁ x = f₂ x) :
is_o f₁ g l → is_o f₂ g l :=
is_o.congr hf (λ _, rfl)
theorem is_o.congr_right {g₁ g₂ : α → E} {l : filter α} (hg : ∀ x, g₁ x = g₂ x) :
is_o f g₁ l → is_o f g₂ l :=
is_o.congr (λ _, rfl) hg
/-! ### Filter operations and transitivity -/
theorem is_O_with.comp_tendsto (hcfg : is_O_with c f g l)
{k : β → α} {l' : filter β} (hk : tendsto k l' l):
is_O_with c (f ∘ k) (g ∘ k) l' :=
is_O_with.of_bound $ hk hcfg.bound
theorem is_O.comp_tendsto (hfg : is_O f g l) {k : β → α} {l' : filter β} (hk : tendsto k l' l) :
is_O (f ∘ k) (g ∘ k) l' :=
is_O_iff_is_O_with.2 $ hfg.is_O_with.imp (λ c h, h.comp_tendsto hk)
theorem is_o.comp_tendsto (hfg : is_o f g l) {k : β → α} {l' : filter β} (hk : tendsto k l' l) :
is_o (f ∘ k) (g ∘ k) l' :=
is_o.of_is_O_with $ λ c cpos, (hfg.forall_is_O_with cpos).comp_tendsto hk
@[simp] theorem is_O_with_map {k : β → α} {l : filter β} :
is_O_with c f g (map k l) ↔ is_O_with c (f ∘ k) (g ∘ k) l :=
by { unfold is_O_with, exact mem_map }
@[simp] theorem is_O_map {k : β → α} {l : filter β} :
is_O f g (map k l) ↔ is_O (f ∘ k) (g ∘ k) l :=
by simp only [is_O, is_O_with_map]
@[simp] theorem is_o_map {k : β → α} {l : filter β} :
is_o f g (map k l) ↔ is_o (f ∘ k) (g ∘ k) l :=
by simp only [is_o, is_O_with_map]
theorem is_O_with.mono (h : is_O_with c f g l') (hl : l ≤ l') : is_O_with c f g l :=
is_O_with.of_bound $ hl h.bound
theorem is_O.mono (h : is_O f g l') (hl : l ≤ l') : is_O f g l :=
is_O_iff_is_O_with.2 $ h.is_O_with.imp (λ c h, h.mono hl)
theorem is_o.mono (h : is_o f g l') (hl : l ≤ l') : is_o f g l :=
is_o.of_is_O_with $ λ c cpos, (h.forall_is_O_with cpos).mono hl
theorem is_O_with.trans (hfg : is_O_with c f g l) (hgk : is_O_with c' g k l) (hc : 0 ≤ c) :
is_O_with (c * c') f k l :=
begin
unfold is_O_with at *,
filter_upwards [hfg, hgk] with x hx hx',
calc ∥f x∥ ≤ c * ∥g x∥ : hx
... ≤ c * (c' * ∥k x∥) : mul_le_mul_of_nonneg_left hx' hc
... = c * c' * ∥k x∥ : (mul_assoc _ _ _).symm
end
theorem is_O.trans (hfg : is_O f g' l) (hgk : is_O g' k l) : is_O f k l :=
let ⟨c, cnonneg, hc⟩ := hfg.exists_nonneg, ⟨c', hc'⟩ := hgk.is_O_with in
(hc.trans hc' cnonneg).is_O
theorem is_o.trans_is_O_with (hfg : is_o f g l) (hgk : is_O_with c g k l) (hc : 0 < c) :
is_o f k l :=
begin
unfold is_o at *,
intros c' c'pos,
have : 0 < c' / c, from div_pos c'pos hc,
exact ((hfg this).trans hgk (le_of_lt this)).congr_const (div_mul_cancel _ (ne_of_gt hc))
end
theorem is_o.trans_is_O (hfg : is_o f g l) (hgk : is_O g k' l) : is_o f k' l :=
let ⟨c, cpos, hc⟩ := hgk.exists_pos in hfg.trans_is_O_with hc cpos
theorem is_O_with.trans_is_o (hfg : is_O_with c f g l) (hgk : is_o g k l) (hc : 0 < c) :
is_o f k l :=
begin
unfold is_o at *,
intros c' c'pos,
have : 0 < c' / c, from div_pos c'pos hc,
exact (hfg.trans (hgk this) (le_of_lt hc)).congr_const (mul_div_cancel' _ (ne_of_gt hc))
end
theorem is_O.trans_is_o (hfg : is_O f g' l) (hgk : is_o g' k l) : is_o f k l :=
let ⟨c, cpos, hc⟩ := hfg.exists_pos in hc.trans_is_o hgk cpos
theorem is_o.trans (hfg : is_o f g l) (hgk : is_o g k' l) : is_o f k' l :=
hfg.trans_is_O hgk.is_O
theorem is_o.trans' (hfg : is_o f g' l) (hgk : is_o g' k l) : is_o f k l :=
hfg.is_O.trans_is_o hgk
section
variable (l)
theorem is_O_with_of_le' (hfg : ∀ x, ∥f x∥ ≤ c * ∥g x∥) : is_O_with c f g l :=
is_O_with.of_bound $ univ_mem' hfg
theorem is_O_with_of_le (hfg : ∀ x, ∥f x∥ ≤ ∥g x∥) : is_O_with 1 f g l :=
is_O_with_of_le' l $ λ x, by { rw one_mul, exact hfg x }
theorem is_O_of_le' (hfg : ∀ x, ∥f x∥ ≤ c * ∥g x∥) : is_O f g l :=
(is_O_with_of_le' l hfg).is_O
theorem is_O_of_le (hfg : ∀ x, ∥f x∥ ≤ ∥g x∥) : is_O f g l :=
(is_O_with_of_le l hfg).is_O
end
theorem is_O_with_refl (f : α → E) (l : filter α) : is_O_with 1 f f l :=
is_O_with_of_le l $ λ _, le_rfl
theorem is_O_refl (f : α → E) (l : filter α) : is_O f f l := (is_O_with_refl f l).is_O
theorem is_O_with.trans_le (hfg : is_O_with c f g l) (hgk : ∀ x, ∥g x∥ ≤ ∥k x∥) (hc : 0 ≤ c) :
is_O_with c f k l :=
(hfg.trans (is_O_with_of_le l hgk) hc).congr_const $ mul_one c
theorem is_O.trans_le (hfg : is_O f g' l) (hgk : ∀ x, ∥g' x∥ ≤ ∥k x∥) :
is_O f k l :=
hfg.trans (is_O_of_le l hgk)
theorem is_o.trans_le (hfg : is_o f g l) (hgk : ∀ x, ∥g x∥ ≤ ∥k x∥) :
is_o f k l :=
hfg.trans_is_O_with (is_O_with_of_le _ hgk) zero_lt_one
section bot
variables (c f g)
@[simp] theorem is_O_with_bot : is_O_with c f g ⊥ := is_O_with.of_bound $ trivial
@[simp] theorem is_O_bot : is_O f g ⊥ := (is_O_with_bot 1 f g).is_O
@[simp] theorem is_o_bot : is_o f g ⊥ := is_o.of_is_O_with $ λ c _, is_O_with_bot c f g
end bot
@[simp] theorem is_O_with_pure {x} : is_O_with c f g (pure x) ↔ ∥f x∥ ≤ c * ∥g x∥ := is_O_with_iff
theorem is_O_with.join (h : is_O_with c f g l) (h' : is_O_with c f g l') :
is_O_with c f g (l ⊔ l') :=
is_O_with.of_bound $ mem_sup.2 ⟨h.bound, h'.bound⟩
theorem is_O_with.join' (h : is_O_with c f g' l) (h' : is_O_with c' f g' l') :
is_O_with (max c c') f g' (l ⊔ l') :=
is_O_with.of_bound $
mem_sup.2 ⟨(h.weaken $ le_max_left c c').bound, (h'.weaken $ le_max_right c c').bound⟩
theorem is_O.join (h : is_O f g' l) (h' : is_O f g' l') : is_O f g' (l ⊔ l') :=
let ⟨c, hc⟩ := h.is_O_with, ⟨c', hc'⟩ := h'.is_O_with in (hc.join' hc').is_O
theorem is_o.join (h : is_o f g l) (h' : is_o f g l') :
is_o f g (l ⊔ l') :=
is_o.of_is_O_with $
λ c cpos, (h.forall_is_O_with cpos).join (h'.forall_is_O_with cpos)
/-! ### Simplification : norm -/
@[simp] theorem is_O_with_norm_right : is_O_with c f (λ x, ∥g' x∥) l ↔ is_O_with c f g' l :=
by simp only [is_O_with, norm_norm]
alias is_O_with_norm_right ↔ asymptotics.is_O_with.of_norm_right asymptotics.is_O_with.norm_right
@[simp] theorem is_O_norm_right : is_O f (λ x, ∥g' x∥) l ↔ is_O f g' l :=
by { unfold is_O, exact exists_congr (λ _, is_O_with_norm_right) }
alias is_O_norm_right ↔ asymptotics.is_O.of_norm_right asymptotics.is_O.norm_right
@[simp] theorem is_o_norm_right : is_o f (λ x, ∥g' x∥) l ↔ is_o f g' l :=
by { unfold is_o, exact forall₂_congr (λ _ _, is_O_with_norm_right) }
alias is_o_norm_right ↔ asymptotics.is_o.of_norm_right asymptotics.is_o.norm_right
@[simp] theorem is_O_with_norm_left : is_O_with c (λ x, ∥f' x∥) g l ↔ is_O_with c f' g l :=
by simp only [is_O_with, norm_norm]
alias is_O_with_norm_left ↔ asymptotics.is_O_with.of_norm_left asymptotics.is_O_with.norm_left
@[simp] theorem is_O_norm_left : is_O (λ x, ∥f' x∥) g l ↔ is_O f' g l :=
by { unfold is_O, exact exists_congr (λ _, is_O_with_norm_left) }
alias is_O_norm_left ↔ asymptotics.is_O.of_norm_left asymptotics.is_O.norm_left
@[simp] theorem is_o_norm_left : is_o (λ x, ∥f' x∥) g l ↔ is_o f' g l :=
by { unfold is_o, exact forall₂_congr (λ _ _, is_O_with_norm_left) }
alias is_o_norm_left ↔ asymptotics.is_o.of_norm_left asymptotics.is_o.norm_left
theorem is_O_with_norm_norm :
is_O_with c (λ x, ∥f' x∥) (λ x, ∥g' x∥) l ↔ is_O_with c f' g' l :=
is_O_with_norm_left.trans is_O_with_norm_right
alias is_O_with_norm_norm ↔ asymptotics.is_O_with.of_norm_norm asymptotics.is_O_with.norm_norm
theorem is_O_norm_norm :
is_O (λ x, ∥f' x∥) (λ x, ∥g' x∥) l ↔ is_O f' g' l :=
is_O_norm_left.trans is_O_norm_right
alias is_O_norm_norm ↔ asymptotics.is_O.of_norm_norm asymptotics.is_O.norm_norm
theorem is_o_norm_norm :
is_o (λ x, ∥f' x∥) (λ x, ∥g' x∥) l ↔ is_o f' g' l :=
is_o_norm_left.trans is_o_norm_right
alias is_o_norm_norm ↔ asymptotics.is_o.of_norm_norm asymptotics.is_o.norm_norm
/-! ### Simplification: negate -/
@[simp] theorem is_O_with_neg_right : is_O_with c f (λ x, -(g' x)) l ↔ is_O_with c f g' l :=
by simp only [is_O_with, norm_neg]
alias is_O_with_neg_right ↔ asymptotics.is_O_with.of_neg_right asymptotics.is_O_with.neg_right
@[simp] theorem is_O_neg_right : is_O f (λ x, -(g' x)) l ↔ is_O f g' l :=
by { unfold is_O, exact exists_congr (λ _, is_O_with_neg_right) }
alias is_O_neg_right ↔ asymptotics.is_O.of_neg_right asymptotics.is_O.neg_right
@[simp] theorem is_o_neg_right : is_o f (λ x, -(g' x)) l ↔ is_o f g' l :=
by { unfold is_o, exact forall₂_congr (λ _ _, is_O_with_neg_right) }
alias is_o_neg_right ↔ asymptotics.is_o.of_neg_right asymptotics.is_o.neg_right
@[simp] theorem is_O_with_neg_left : is_O_with c (λ x, -(f' x)) g l ↔ is_O_with c f' g l :=
by simp only [is_O_with, norm_neg]
alias is_O_with_neg_left ↔ asymptotics.is_O_with.of_neg_left asymptotics.is_O_with.neg_left
@[simp] theorem is_O_neg_left : is_O (λ x, -(f' x)) g l ↔ is_O f' g l :=
by { unfold is_O, exact exists_congr (λ _, is_O_with_neg_left) }
alias is_O_neg_left ↔ asymptotics.is_O.of_neg_left asymptotics.is_O.neg_left
@[simp] theorem is_o_neg_left : is_o (λ x, -(f' x)) g l ↔ is_o f' g l :=
by { unfold is_o, exact forall₂_congr (λ _ _, is_O_with_neg_left) }
alias is_o_neg_left ↔ asymptotics.is_o.of_neg_right asymptotics.is_o.neg_left
/-! ### Product of functions (right) -/
lemma is_O_with_fst_prod : is_O_with 1 f' (λ x, (f' x, g' x)) l :=
is_O_with_of_le l $ λ x, le_max_left _ _
lemma is_O_with_snd_prod : is_O_with 1 g' (λ x, (f' x, g' x)) l :=
is_O_with_of_le l $ λ x, le_max_right _ _
lemma is_O_fst_prod : is_O f' (λ x, (f' x, g' x)) l := is_O_with_fst_prod.is_O
lemma is_O_snd_prod : is_O g' (λ x, (f' x, g' x)) l := is_O_with_snd_prod.is_O
lemma is_O_fst_prod' {f' : α → E' × F'} : is_O (λ x, (f' x).1) f' l :=
by simpa [is_O, is_O_with] using is_O_fst_prod
lemma is_O_snd_prod' {f' : α → E' × F'} : is_O (λ x, (f' x).2) f' l :=
by simpa [is_O, is_O_with] using is_O_snd_prod
section
variables (f' k')
lemma is_O_with.prod_rightl (h : is_O_with c f g' l) (hc : 0 ≤ c) :
is_O_with c f (λ x, (g' x, k' x)) l :=
(h.trans is_O_with_fst_prod hc).congr_const (mul_one c)
lemma is_O.prod_rightl (h : is_O f g' l) : is_O f (λx, (g' x, k' x)) l :=
let ⟨c, cnonneg, hc⟩ := h.exists_nonneg in (hc.prod_rightl k' cnonneg).is_O
lemma is_o.prod_rightl (h : is_o f g' l) : is_o f (λ x, (g' x, k' x)) l :=
is_o.of_is_O_with $
λ c cpos, (h.forall_is_O_with cpos).prod_rightl k' (le_of_lt cpos)
lemma is_O_with.prod_rightr (h : is_O_with c f g' l) (hc : 0 ≤ c) :
is_O_with c f (λ x, (f' x, g' x)) l :=
(h.trans is_O_with_snd_prod hc).congr_const (mul_one c)
lemma is_O.prod_rightr (h : is_O f g' l) : is_O f (λx, (f' x, g' x)) l :=
let ⟨c, cnonneg, hc⟩ := h.exists_nonneg in (hc.prod_rightr f' cnonneg).is_O
lemma is_o.prod_rightr (h : is_o f g' l) : is_o f (λx, (f' x, g' x)) l :=
is_o.of_is_O_with $
λ c cpos, (h.forall_is_O_with cpos).prod_rightr f' (le_of_lt cpos)
end
lemma is_O_with.prod_left_same (hf : is_O_with c f' k' l) (hg : is_O_with c g' k' l) :
is_O_with c (λ x, (f' x, g' x)) k' l :=
by rw is_O_with_iff at *; filter_upwards [hf, hg] with x using max_le
lemma is_O_with.prod_left (hf : is_O_with c f' k' l) (hg : is_O_with c' g' k' l) :
is_O_with (max c c') (λ x, (f' x, g' x)) k' l :=
(hf.weaken $ le_max_left c c').prod_left_same (hg.weaken $ le_max_right c c')
lemma is_O_with.prod_left_fst (h : is_O_with c (λ x, (f' x, g' x)) k' l) :
is_O_with c f' k' l :=
(is_O_with_fst_prod.trans h zero_le_one).congr_const $ one_mul c
lemma is_O_with.prod_left_snd (h : is_O_with c (λ x, (f' x, g' x)) k' l) :
is_O_with c g' k' l :=
(is_O_with_snd_prod.trans h zero_le_one).congr_const $ one_mul c
lemma is_O_with_prod_left :
is_O_with c (λ x, (f' x, g' x)) k' l ↔ is_O_with c f' k' l ∧ is_O_with c g' k' l :=
⟨λ h, ⟨h.prod_left_fst, h.prod_left_snd⟩, λ h, h.1.prod_left_same h.2⟩
lemma is_O.prod_left (hf : is_O f' k' l) (hg : is_O g' k' l) : is_O (λ x, (f' x, g' x)) k' l :=
let ⟨c, hf⟩ := hf.is_O_with, ⟨c', hg⟩ := hg.is_O_with in (hf.prod_left hg).is_O
lemma is_O.prod_left_fst (h : is_O (λ x, (f' x, g' x)) k' l) : is_O f' k' l :=
is_O_fst_prod.trans h
lemma is_O.prod_left_snd (h : is_O (λ x, (f' x, g' x)) k' l) : is_O g' k' l :=
is_O_snd_prod.trans h
@[simp] lemma is_O_prod_left :
is_O (λ x, (f' x, g' x)) k' l ↔ is_O f' k' l ∧ is_O g' k' l :=
⟨λ h, ⟨h.prod_left_fst, h.prod_left_snd⟩, λ h, h.1.prod_left h.2⟩
lemma is_o.prod_left (hf : is_o f' k' l) (hg : is_o g' k' l) : is_o (λ x, (f' x, g' x)) k' l :=
is_o.of_is_O_with $
λ c hc, (hf.forall_is_O_with hc).prod_left_same (hg.forall_is_O_with hc)
lemma is_o.prod_left_fst (h : is_o (λ x, (f' x, g' x)) k' l) : is_o f' k' l :=
is_O_fst_prod.trans_is_o h
lemma is_o.prod_left_snd (h : is_o (λ x, (f' x, g' x)) k' l) : is_o g' k' l :=
is_O_snd_prod.trans_is_o h
@[simp] lemma is_o_prod_left :
is_o (λ x, (f' x, g' x)) k' l ↔ is_o f' k' l ∧ is_o g' k' l :=
⟨λ h, ⟨h.prod_left_fst, h.prod_left_snd⟩, λ h, h.1.prod_left h.2⟩
lemma is_O_with.eq_zero_imp (h : is_O_with c f'' g'' l) : ∀ᶠ x in l, g'' x = 0 → f'' x = 0 :=
eventually.mono h.bound $ λ x hx hg, norm_le_zero_iff.1 $ by simpa [hg] using hx
lemma is_O.eq_zero_imp (h : is_O f'' g'' l) : ∀ᶠ x in l, g'' x = 0 → f'' x = 0 :=
let ⟨C, hC⟩ := h.is_O_with in hC.eq_zero_imp
/-! ### Addition and subtraction -/
section add_sub
variables {c₁ c₂ : ℝ} {f₁ f₂ : α → E'}
theorem is_O_with.add (h₁ : is_O_with c₁ f₁ g l) (h₂ : is_O_with c₂ f₂ g l) :
is_O_with (c₁ + c₂) (λ x, f₁ x + f₂ x) g l :=
by rw is_O_with at *; filter_upwards [h₁, h₂] with x hx₁ hx₂ using
calc ∥f₁ x + f₂ x∥ ≤ c₁ * ∥g x∥ + c₂ * ∥g x∥ : norm_add_le_of_le hx₁ hx₂
... = (c₁ + c₂) * ∥g x∥ : (add_mul _ _ _).symm
theorem is_O.add (h₁ : is_O f₁ g l) (h₂ : is_O f₂ g l) : is_O (λ x, f₁ x + f₂ x) g l :=
let ⟨c₁, hc₁⟩ := h₁.is_O_with, ⟨c₂, hc₂⟩ := h₂.is_O_with in (hc₁.add hc₂).is_O
theorem is_o.add (h₁ : is_o f₁ g l) (h₂ : is_o f₂ g l) : is_o (λ x, f₁ x + f₂ x) g l :=
is_o.of_is_O_with $ λ c cpos, ((h₁.forall_is_O_with $ half_pos cpos).add
(h₂.forall_is_O_with $ half_pos cpos)).congr_const (add_halves c)
theorem is_o.add_add {g₁ g₂ : α → F'} (h₁ : is_o f₁ g₁ l) (h₂ : is_o f₂ g₂ l) :
is_o (λ x, f₁ x + f₂ x) (λ x, ∥g₁ x∥ + ∥g₂ x∥) l :=
by refine (h₁.trans_le $ λ x, _).add (h₂.trans_le _);
simp [real.norm_eq_abs, abs_of_nonneg, add_nonneg]
theorem is_O.add_is_o (h₁ : is_O f₁ g l) (h₂ : is_o f₂ g l) : is_O (λ x, f₁ x + f₂ x) g l :=
h₁.add h₂.is_O
theorem is_o.add_is_O (h₁ : is_o f₁ g l) (h₂ : is_O f₂ g l) : is_O (λ x, f₁ x + f₂ x) g l :=
h₁.is_O.add h₂
theorem is_O_with.add_is_o (h₁ : is_O_with c₁ f₁ g l) (h₂ : is_o f₂ g l) (hc : c₁ < c₂) :
is_O_with c₂ (λx, f₁ x + f₂ x) g l :=
(h₁.add (h₂.forall_is_O_with (sub_pos.2 hc))).congr_const (add_sub_cancel'_right _ _)
theorem is_o.add_is_O_with (h₁ : is_o f₁ g l) (h₂ : is_O_with c₁ f₂ g l) (hc : c₁ < c₂) :
is_O_with c₂ (λx, f₁ x + f₂ x) g l :=
(h₂.add_is_o h₁ hc).congr_left $ λ _, add_comm _ _
theorem is_O_with.sub (h₁ : is_O_with c₁ f₁ g l) (h₂ : is_O_with c₂ f₂ g l) :
is_O_with (c₁ + c₂) (λ x, f₁ x - f₂ x) g l :=
by simpa only [sub_eq_add_neg] using h₁.add h₂.neg_left
theorem is_O_with.sub_is_o (h₁ : is_O_with c₁ f₁ g l) (h₂ : is_o f₂ g l) (hc : c₁ < c₂) :
is_O_with c₂ (λ x, f₁ x - f₂ x) g l :=
by simpa only [sub_eq_add_neg] using h₁.add_is_o h₂.neg_left hc
theorem is_O.sub (h₁ : is_O f₁ g l) (h₂ : is_O f₂ g l) : is_O (λ x, f₁ x - f₂ x) g l :=
by simpa only [sub_eq_add_neg] using h₁.add h₂.neg_left
theorem is_o.sub (h₁ : is_o f₁ g l) (h₂ : is_o f₂ g l) : is_o (λ x, f₁ x - f₂ x) g l :=
by simpa only [sub_eq_add_neg] using h₁.add h₂.neg_left
end add_sub
/-! ### Lemmas about `is_O (f₁ - f₂) g l` / `is_o (f₁ - f₂) g l` treated as a binary relation -/
section is_oO_as_rel
variables {f₁ f₂ f₃ : α → E'}
theorem is_O_with.symm (h : is_O_with c (λ x, f₁ x - f₂ x) g l) :
is_O_with c (λ x, f₂ x - f₁ x) g l :=
h.neg_left.congr_left $ λ x, neg_sub _ _
theorem is_O_with_comm :
is_O_with c (λ x, f₁ x - f₂ x) g l ↔ is_O_with c (λ x, f₂ x - f₁ x) g l :=
⟨is_O_with.symm, is_O_with.symm⟩
theorem is_O.symm (h : is_O (λ x, f₁ x - f₂ x) g l) : is_O (λ x, f₂ x - f₁ x) g l :=
h.neg_left.congr_left $ λ x, neg_sub _ _
theorem is_O_comm : is_O (λ x, f₁ x - f₂ x) g l ↔ is_O (λ x, f₂ x - f₁ x) g l :=
⟨is_O.symm, is_O.symm⟩
theorem is_o.symm (h : is_o (λ x, f₁ x - f₂ x) g l) : is_o (λ x, f₂ x - f₁ x) g l :=
by simpa only [neg_sub] using h.neg_left
theorem is_o_comm : is_o (λ x, f₁ x - f₂ x) g l ↔ is_o (λ x, f₂ x - f₁ x) g l :=
⟨is_o.symm, is_o.symm⟩
theorem is_O_with.triangle (h₁ : is_O_with c (λ x, f₁ x - f₂ x) g l)
(h₂ : is_O_with c' (λ x, f₂ x - f₃ x) g l) :
is_O_with (c + c') (λ x, f₁ x - f₃ x) g l :=
(h₁.add h₂).congr_left $ λ x, sub_add_sub_cancel _ _ _
theorem is_O.triangle (h₁ : is_O (λ x, f₁ x - f₂ x) g l) (h₂ : is_O (λ x, f₂ x - f₃ x) g l) :
is_O (λ x, f₁ x - f₃ x) g l :=
(h₁.add h₂).congr_left $ λ x, sub_add_sub_cancel _ _ _
theorem is_o.triangle (h₁ : is_o (λ x, f₁ x - f₂ x) g l) (h₂ : is_o (λ x, f₂ x - f₃ x) g l) :
is_o (λ x, f₁ x - f₃ x) g l :=
(h₁.add h₂).congr_left $ λ x, sub_add_sub_cancel _ _ _
theorem is_O.congr_of_sub (h : is_O (λ x, f₁ x - f₂ x) g l) :
is_O f₁ g l ↔ is_O f₂ g l :=
⟨λ h', (h'.sub h).congr_left (λ x, sub_sub_cancel _ _),
λ h', (h.add h').congr_left (λ x, sub_add_cancel _ _)⟩
theorem is_o.congr_of_sub (h : is_o (λ x, f₁ x - f₂ x) g l) :
is_o f₁ g l ↔ is_o f₂ g l :=
⟨λ h', (h'.sub h).congr_left (λ x, sub_sub_cancel _ _),
λ h', (h.add h').congr_left (λ x, sub_add_cancel _ _)⟩
end is_oO_as_rel
/-! ### Zero, one, and other constants -/
section zero_const
variables (g g' l)
theorem is_o_zero : is_o (λ x, (0 : E')) g' l :=
is_o.of_bound $ λ c hc, univ_mem' $ λ x,
by simpa using mul_nonneg hc.le (norm_nonneg $ g' x)
theorem is_O_with_zero (hc : 0 ≤ c) : is_O_with c (λ x, (0 : E')) g' l :=
is_O_with.of_bound $ univ_mem' $ λ x, by simpa using mul_nonneg hc (norm_nonneg $ g' x)
theorem is_O_with_zero' : is_O_with 0 (λ x, (0 : E')) g l :=
is_O_with.of_bound $ univ_mem' $ λ x, by simp
theorem is_O_zero : is_O (λ x, (0 : E')) g l :=
is_O_iff_is_O_with.2 ⟨0, is_O_with_zero' _ _⟩
theorem is_O_refl_left : is_O (λ x, f' x - f' x) g' l :=
(is_O_zero g' l).congr_left $ λ x, (sub_self _).symm
theorem is_o_refl_left : is_o (λ x, f' x - f' x) g' l :=
(is_o_zero g' l).congr_left $ λ x, (sub_self _).symm
variables {g g' l}
@[simp] theorem is_O_with_zero_right_iff :
is_O_with c f'' (λ x, (0 : F'')) l ↔ ∀ᶠ x in l, f'' x = 0 :=
by simp only [is_O_with, exists_prop, true_and, norm_zero, mul_zero, norm_le_zero_iff]
@[simp] theorem is_O_zero_right_iff : is_O f'' (λ x, (0 : F'')) l ↔ ∀ᶠ x in l, f'' x = 0 :=
⟨λ h, let ⟨c, hc⟩ := h.is_O_with in is_O_with_zero_right_iff.1 hc,
λ h, (is_O_with_zero_right_iff.2 h : is_O_with 1 _ _ _).is_O⟩
@[simp] theorem is_o_zero_right_iff :
is_o f'' (λ x, (0 : F'')) l ↔ ∀ᶠ x in l, f'' x = 0 :=
⟨λ h, is_O_zero_right_iff.1 h.is_O,
λ h, is_o.of_is_O_with $ λ c hc, is_O_with_zero_right_iff.2 h⟩
theorem is_O_with_const_const (c : E) {c' : F''} (hc' : c' ≠ 0) (l : filter α) :
is_O_with (∥c∥ / ∥c'∥) (λ x : α, c) (λ x, c') l :=
begin
unfold is_O_with,
apply univ_mem',
intro x,
rw [mem_set_of_eq, div_mul_cancel],
rwa [ne.def, norm_eq_zero]
end
theorem is_O_const_const (c : E) {c' : F''} (hc' : c' ≠ 0) (l : filter α) :
is_O (λ x : α, c) (λ x, c') l :=
(is_O_with_const_const c hc' l).is_O
@[simp] theorem is_O_const_const_iff {c : E''} {c' : F''} (l : filter α) [l.ne_bot] :
is_O (λ x : α, c) (λ x, c') l ↔ (c' = 0 → c = 0) :=
begin
rcases eq_or_ne c' 0 with rfl|hc',
{ simp },
{ simp [hc', is_O_const_const _ hc'] }
end
@[simp] lemma is_O_pure {x} : is_O f'' g'' (pure x) ↔ (g'' x = 0 → f'' x = 0) :=
calc is_O f'' g'' (pure x) ↔ is_O (λ y : α, f'' x) (λ _, g'' x) (pure x) : is_O_congr rfl rfl
... ↔ g'' x = 0 → f'' x = 0 : is_O_const_const_iff _
end zero_const
@[simp] lemma is_O_with_top : is_O_with c f g ⊤ ↔ ∀ x, ∥f x∥ ≤ c * ∥g x∥ := by rw is_O_with; refl
@[simp] lemma is_O_top : is_O f g ⊤ ↔ ∃ C, ∀ x, ∥f x∥ ≤ C * ∥g x∥ := by rw is_O_iff; refl
@[simp] lemma is_o_top : is_o f'' g'' ⊤ ↔ ∀ x, f'' x = 0 :=
begin
refine ⟨_, λ h, (is_o_zero g'' ⊤).congr (λ x, (h x).symm) (λ x, rfl)⟩,
simp only [is_o_iff, eventually_top],
refine λ h x, norm_le_zero_iff.1 _,
have : tendsto (λ c : ℝ, c * ∥g'' x∥) (𝓝[>] 0) (𝓝 0) :=
((continuous_id.mul continuous_const).tendsto' _ _ (zero_mul _)).mono_left inf_le_left,
exact le_of_tendsto_of_tendsto tendsto_const_nhds this
(eventually_nhds_within_iff.2 $ eventually_of_forall $ λ c hc, h hc x)
end
@[simp] lemma is_O_with_principal {s : set α} :
is_O_with c f g (𝓟 s) ↔ ∀ x ∈ s, ∥f x∥ ≤ c * ∥g x∥ :=
by rw is_O_with; refl
lemma is_O_principal {s : set α} :
is_O f g (𝓟 s) ↔ ∃ c, ∀ x ∈ s, ∥f x∥ ≤ c * ∥g x∥ :=
by rw is_O_iff; refl
theorem is_O_with_const_one (c : E) (l : filter α) : is_O_with ∥c∥ (λ x : α, c) (λ x, (1 : 𝕜)) l :=
begin
refine (is_O_with_const_const c _ l).congr_const _,
{ rw [norm_one, div_one] },
{ exact one_ne_zero }
end
theorem is_O_const_one (c : E) (l : filter α) : is_O (λ x : α, c) (λ x, (1 : 𝕜)) l :=
(is_O_with_const_one c l).is_O
section
variable (𝕜)
theorem is_o_const_iff_is_o_one {c : F''} (hc : c ≠ 0) :
is_o f (λ x, c) l ↔ is_o f (λ x, (1:𝕜)) l :=
⟨λ h, h.trans_is_O $ is_O_const_one c l, λ h, h.trans_is_O $ is_O_const_const _ hc _⟩
end
theorem is_o_const_iff {c : F''} (hc : c ≠ 0) :
is_o f'' (λ x, c) l ↔ tendsto f'' l (𝓝 0) :=
(is_o_const_iff_is_o_one ℝ hc).trans
begin
clear hc c,
simp only [is_o, is_O_with, norm_one, mul_one, metric.nhds_basis_closed_ball.tendsto_right_iff,
metric.mem_closed_ball, dist_zero_right]
end
lemma is_o_id_const {c : F''} (hc : c ≠ 0) :
is_o (λ (x : E''), x) (λ x, c) (𝓝 0) :=
(is_o_const_iff hc).mpr (continuous_id.tendsto 0)
theorem _root_.filter.is_bounded_under.is_O_const (h : is_bounded_under (≤) l (norm ∘ f))
{c : F''} (hc : c ≠ 0) : is_O f (λ x, c) l :=
begin
rcases h with ⟨C, hC⟩,
refine (is_O.of_bound 1 _).trans (is_O_const_const C hc l),
refine (eventually_map.1 hC).mono (λ x h, _),
calc ∥f x∥ ≤ C : h
... ≤ abs C : le_abs_self C
... = 1 * ∥C∥ : (one_mul _).symm
end
theorem is_O_const_of_tendsto {y : E''} (h : tendsto f'' l (𝓝 y)) {c : F''} (hc : c ≠ 0) :
is_O f'' (λ x, c) l :=
h.norm.is_bounded_under_le.is_O_const hc
section
variable (𝕜)
theorem is_o_one_iff : is_o f'' (λ x, (1 : 𝕜)) l ↔ tendsto f'' l (𝓝 0) :=
is_o_const_iff one_ne_zero
theorem is_O_one_of_tendsto {y : E''} (h : tendsto f'' l (𝓝 y)) :
is_O f'' (λ x, (1:𝕜)) l :=
is_O_const_of_tendsto h one_ne_zero
theorem is_O.trans_tendsto_nhds (hfg : is_O f g'' l) {y : F''} (hg : tendsto g'' l (𝓝 y)) :
is_O f (λ x, (1:𝕜)) l :=
hfg.trans $ is_O_one_of_tendsto 𝕜 hg
end
theorem is_O.trans_tendsto (hfg : is_O f'' g'' l) (hg : tendsto g'' l (𝓝 0)) :
tendsto f'' l (𝓝 0) :=
(is_o_one_iff ℝ).1 $ hfg.trans_is_o $ (is_o_one_iff ℝ).2 hg
theorem is_o.trans_tendsto (hfg : is_o f'' g'' l) (hg : tendsto g'' l (𝓝 0)) :
tendsto f'' l (𝓝 0) :=
hfg.is_O.trans_tendsto hg
/-! ### Multiplication by a constant -/
theorem is_O_with_const_mul_self (c : R) (f : α → R) (l : filter α) :
is_O_with ∥c∥ (λ x, c * f x) f l :=
is_O_with_of_le' _ $ λ x, norm_mul_le _ _
theorem is_O_const_mul_self (c : R) (f : α → R) (l : filter α) :
is_O (λ x, c * f x) f l :=
(is_O_with_const_mul_self c f l).is_O
theorem is_O_with.const_mul_left {f : α → R} (h : is_O_with c f g l) (c' : R) :
is_O_with (∥c'∥ * c) (λ x, c' * f x) g l :=
(is_O_with_const_mul_self c' f l).trans h (norm_nonneg c')
theorem is_O.const_mul_left {f : α → R} (h : is_O f g l) (c' : R) :
is_O (λ x, c' * f x) g l :=
let ⟨c, hc⟩ := h.is_O_with in (hc.const_mul_left c').is_O
theorem is_O_with_self_const_mul' (u : Rˣ) (f : α → R) (l : filter α) :
is_O_with ∥(↑u⁻¹:R)∥ f (λ x, ↑u * f x) l :=
(is_O_with_const_mul_self ↑u⁻¹ _ l).congr_left $ λ x, u.inv_mul_cancel_left (f x)
theorem is_O_with_self_const_mul (c : 𝕜) (hc : c ≠ 0) (f : α → 𝕜) (l : filter α) :
is_O_with ∥c∥⁻¹ f (λ x, c * f x) l :=
(is_O_with_self_const_mul' (units.mk0 c hc) f l).congr_const $
norm_inv c
theorem is_O_self_const_mul' {c : R} (hc : is_unit c) (f : α → R) (l : filter α) :
is_O f (λ x, c * f x) l :=
let ⟨u, hu⟩ := hc in hu ▸ (is_O_with_self_const_mul' u f l).is_O
theorem is_O_self_const_mul (c : 𝕜) (hc : c ≠ 0) (f : α → 𝕜) (l : filter α) :
is_O f (λ x, c * f x) l :=
is_O_self_const_mul' (is_unit.mk0 c hc) f l
theorem is_O_const_mul_left_iff' {f : α → R} {c : R} (hc : is_unit c) :
is_O (λ x, c * f x) g l ↔ is_O f g l :=
⟨(is_O_self_const_mul' hc f l).trans, λ h, h.const_mul_left c⟩
theorem is_O_const_mul_left_iff {f : α → 𝕜} {c : 𝕜} (hc : c ≠ 0) :
is_O (λ x, c * f x) g l ↔ is_O f g l :=
is_O_const_mul_left_iff' $ is_unit.mk0 c hc
theorem is_o.const_mul_left {f : α → R} (h : is_o f g l) (c : R) :
is_o (λ x, c * f x) g l :=
(is_O_const_mul_self c f l).trans_is_o h
theorem is_o_const_mul_left_iff' {f : α → R} {c : R} (hc : is_unit c) :
is_o (λ x, c * f x) g l ↔ is_o f g l :=
⟨(is_O_self_const_mul' hc f l).trans_is_o, λ h, h.const_mul_left c⟩
theorem is_o_const_mul_left_iff {f : α → 𝕜} {c : 𝕜} (hc : c ≠ 0) :
is_o (λ x, c * f x) g l ↔ is_o f g l :=
is_o_const_mul_left_iff' $ is_unit.mk0 c hc
theorem is_O_with.of_const_mul_right {g : α → R} {c : R} (hc' : 0 ≤ c')
(h : is_O_with c' f (λ x, c * g x) l) :
is_O_with (c' * ∥c∥) f g l :=
h.trans (is_O_with_const_mul_self c g l) hc'
theorem is_O.of_const_mul_right {g : α → R} {c : R}
(h : is_O f (λ x, c * g x) l) :
is_O f g l :=
let ⟨c, cnonneg, hc⟩ := h.exists_nonneg in (hc.of_const_mul_right cnonneg).is_O
theorem is_O_with.const_mul_right' {g : α → R} {u : Rˣ} {c' : ℝ} (hc' : 0 ≤ c')
(h : is_O_with c' f g l) :
is_O_with (c' * ∥(↑u⁻¹:R)∥) f (λ x, ↑u * g x) l :=
h.trans (is_O_with_self_const_mul' _ _ _) hc'
theorem is_O_with.const_mul_right {g : α → 𝕜} {c : 𝕜} (hc : c ≠ 0)
{c' : ℝ} (hc' : 0 ≤ c') (h : is_O_with c' f g l) :
is_O_with (c' * ∥c∥⁻¹) f (λ x, c * g x) l :=
h.trans (is_O_with_self_const_mul c hc g l) hc'
theorem is_O.const_mul_right' {g : α → R} {c : R} (hc : is_unit c) (h : is_O f g l) :
is_O f (λ x, c * g x) l :=
h.trans (is_O_self_const_mul' hc g l)
theorem is_O.const_mul_right {g : α → 𝕜} {c : 𝕜} (hc : c ≠ 0) (h : is_O f g l) :
is_O f (λ x, c * g x) l :=
h.const_mul_right' $ is_unit.mk0 c hc
theorem is_O_const_mul_right_iff' {g : α → R} {c : R} (hc : is_unit c) :
is_O f (λ x, c * g x) l ↔ is_O f g l :=
⟨λ h, h.of_const_mul_right, λ h, h.const_mul_right' hc⟩
theorem is_O_const_mul_right_iff {g : α → 𝕜} {c : 𝕜} (hc : c ≠ 0) :
is_O f (λ x, c * g x) l ↔ is_O f g l :=
is_O_const_mul_right_iff' $ is_unit.mk0 c hc
theorem is_o.of_const_mul_right {g : α → R} {c : R} (h : is_o f (λ x, c * g x) l) :
is_o f g l :=
h.trans_is_O (is_O_const_mul_self c g l)
theorem is_o.const_mul_right' {g : α → R} {c : R} (hc : is_unit c) (h : is_o f g l) :
is_o f (λ x, c * g x) l :=
h.trans_is_O (is_O_self_const_mul' hc g l)
theorem is_o.const_mul_right {g : α → 𝕜} {c : 𝕜} (hc : c ≠ 0) (h : is_o f g l) :
is_o f (λ x, c * g x) l :=
h.const_mul_right' $ is_unit.mk0 c hc
theorem is_o_const_mul_right_iff' {g : α → R} {c : R} (hc : is_unit c) :
is_o f (λ x, c * g x) l ↔ is_o f g l :=
⟨λ h, h.of_const_mul_right, λ h, h.const_mul_right' hc⟩
theorem is_o_const_mul_right_iff {g : α → 𝕜} {c : 𝕜} (hc : c ≠ 0) :
is_o f (λ x, c * g x) l ↔ is_o f g l :=
is_o_const_mul_right_iff' $ is_unit.mk0 c hc
/-! ### Multiplication -/
theorem is_O_with.mul {f₁ f₂ : α → R} {g₁ g₂ : α → 𝕜} {c₁ c₂ : ℝ}
(h₁ : is_O_with c₁ f₁ g₁ l) (h₂ : is_O_with c₂ f₂ g₂ l) :
is_O_with (c₁ * c₂) (λ x, f₁ x * f₂ x) (λ x, g₁ x * g₂ x) l :=
begin
unfold is_O_with at *,
filter_upwards [h₁, h₂] with _ hx₁ hx₂,
apply le_trans (norm_mul_le _ _),
convert mul_le_mul hx₁ hx₂ (norm_nonneg _) (le_trans (norm_nonneg _) hx₁) using 1,
rw [norm_mul, mul_mul_mul_comm]
end
theorem is_O.mul {f₁ f₂ : α → R} {g₁ g₂ : α → 𝕜}
(h₁ : is_O f₁ g₁ l) (h₂ : is_O f₂ g₂ l) :
is_O (λ x, f₁ x * f₂ x) (λ x, g₁ x * g₂ x) l :=
let ⟨c, hc⟩ := h₁.is_O_with, ⟨c', hc'⟩ := h₂.is_O_with in (hc.mul hc').is_O
theorem is_O.mul_is_o {f₁ f₂ : α → R} {g₁ g₂ : α → 𝕜}
(h₁ : is_O f₁ g₁ l) (h₂ : is_o f₂ g₂ l) :
is_o (λ x, f₁ x * f₂ x) (λ x, g₁ x * g₂ x) l :=
begin
unfold is_o at *,
intros c cpos,
rcases h₁.exists_pos with ⟨c', c'pos, hc'⟩,
exact (hc'.mul (h₂ (div_pos cpos c'pos))).congr_const (mul_div_cancel' _ (ne_of_gt c'pos))
end
theorem is_o.mul_is_O {f₁ f₂ : α → R} {g₁ g₂ : α → 𝕜}
(h₁ : is_o f₁ g₁ l) (h₂ : is_O f₂ g₂ l) :
is_o (λ x, f₁ x * f₂ x) (λ x, g₁ x * g₂ x) l :=
begin
unfold is_o at *,
intros c cpos,
rcases h₂.exists_pos with ⟨c', c'pos, hc'⟩,
exact ((h₁ (div_pos cpos c'pos)).mul hc').congr_const (div_mul_cancel _ (ne_of_gt c'pos))
end
theorem is_o.mul {f₁ f₂ : α → R} {g₁ g₂ : α → 𝕜} (h₁ : is_o f₁ g₁ l) (h₂ : is_o f₂ g₂ l) :
is_o (λ x, f₁ x * f₂ x) (λ x, g₁ x * g₂ x) l :=
h₁.mul_is_O h₂.is_O
theorem is_O_with.pow' {f : α → R} {g : α → 𝕜} (h : is_O_with c f g l) :
∀ n : ℕ, is_O_with (nat.cases_on n ∥(1 : R)∥ (λ n, c ^ (n + 1))) (λ x, f x ^ n) (λ x, g x ^ n) l
| 0 := by simpa using is_O_with_const_const (1 : R) (@one_ne_zero 𝕜 _ _) l
| 1 := by simpa
| (n + 2) := by simpa [pow_succ] using h.mul (is_O_with.pow' (n + 1))
theorem is_O_with.pow [norm_one_class R] {f : α → R} {g : α → 𝕜} (h : is_O_with c f g l) :
∀ n : ℕ, is_O_with (c ^ n) (λ x, f x ^ n) (λ x, g x ^ n) l
| 0 := by simpa using h.pow' 0
| (n + 1) := h.pow' (n + 1)
theorem is_O.pow {f : α → R} {g : α → 𝕜} (h : is_O f g l) (n : ℕ) :
is_O (λ x, f x ^ n) (λ x, g x ^ n) l :=
let ⟨C, hC⟩ := h.is_O_with in is_O_iff_is_O_with.2 ⟨_, hC.pow' n⟩
theorem is_o.pow {f : α → R} {g : α → 𝕜} (h : is_o f g l) {n : ℕ} (hn : 0 < n) :
is_o (λ x, f x ^ n) (λ x, g x ^ n) l :=
begin
cases n, exact hn.false.elim, clear hn,
induction n with n ihn, { simpa only [pow_one] },
convert h.mul ihn; simp [pow_succ]
end
/-! ### Inverse -/
theorem is_O_with.inv_rev {f : α → 𝕜} {g : α → 𝕜'} (h : is_O_with c f g l)
(h₀ : ∀ᶠ x in l, f x ≠ 0) : is_O_with c (λ x, (g x)⁻¹) (λ x, (f x)⁻¹) l :=
begin
refine is_O_with.of_bound (h.bound.mp (h₀.mono $ λ x h₀ hle, _)),
cases le_or_lt c 0 with hc hc,
{ refine (h₀ $ norm_le_zero_iff.1 _).elim,
exact hle.trans (mul_nonpos_of_nonpos_of_nonneg hc $ norm_nonneg _) },
{ replace hle := inv_le_inv_of_le (norm_pos_iff.2 h₀) hle,
simpa only [norm_inv, mul_inv, ← div_eq_inv_mul, div_le_iff hc] using hle }
end
theorem is_O.inv_rev {f : α → 𝕜} {g : α → 𝕜'} (h : is_O f g l)
(h₀ : ∀ᶠ x in l, f x ≠ 0) : is_O (λ x, (g x)⁻¹) (λ x, (f x)⁻¹) l :=
let ⟨c, hc⟩ := h.is_O_with in (hc.inv_rev h₀).is_O
theorem is_o.inv_rev {f : α → 𝕜} {g : α → 𝕜'} (h : is_o f g l)
(h₀ : ∀ᶠ x in l, f x ≠ 0) : is_o (λ x, (g x)⁻¹) (λ x, (f x)⁻¹) l :=
is_o.of_is_O_with $ λ c hc, (h.def' hc).inv_rev h₀
/-! ### Scalar multiplication -/
section smul_const
variables [normed_space 𝕜 E']
theorem is_O_with.const_smul_left (h : is_O_with c f' g l) (c' : 𝕜) :
is_O_with (∥c'∥ * c) (λ x, c' • f' x) g l :=
by refine ((h.norm_left.const_mul_left (∥c'∥)).congr _ _ (λ _, rfl)).of_norm_left;
intros; simp only [norm_norm, norm_smul]
theorem is_O_const_smul_left_iff {c : 𝕜} (hc : c ≠ 0) :
is_O (λ x, c • f' x) g l ↔ is_O f' g l :=
begin
have cne0 : ∥c∥ ≠ 0, from mt norm_eq_zero.mp hc,
rw [←is_O_norm_left], simp only [norm_smul],
rw [is_O_const_mul_left_iff cne0, is_O_norm_left],
end
theorem is_o_const_smul_left (h : is_o f' g l) (c : 𝕜) :
is_o (λ x, c • f' x) g l :=
begin
refine ((h.norm_left.const_mul_left (∥c∥)).congr_left _).of_norm_left,
exact λ x, (norm_smul _ _).symm
end
theorem is_o_const_smul_left_iff {c : 𝕜} (hc : c ≠ 0) :
is_o (λ x, c • f' x) g l ↔ is_o f' g l :=
begin
have cne0 : ∥c∥ ≠ 0, from mt norm_eq_zero.mp hc,
rw [←is_o_norm_left], simp only [norm_smul],
rw [is_o_const_mul_left_iff cne0, is_o_norm_left]
end
theorem is_O_const_smul_right {c : 𝕜} (hc : c ≠ 0) :
is_O f (λ x, c • f' x) l ↔ is_O f f' l :=
begin
have cne0 : ∥c∥ ≠ 0, from mt norm_eq_zero.mp hc,
rw [←is_O_norm_right], simp only [norm_smul],
rw [is_O_const_mul_right_iff cne0, is_O_norm_right]
end
theorem is_o_const_smul_right {c : 𝕜} (hc : c ≠ 0) :
is_o f (λ x, c • f' x) l ↔ is_o f f' l :=
begin
have cne0 : ∥c∥ ≠ 0, from mt norm_eq_zero.mp hc,
rw [←is_o_norm_right], simp only [norm_smul],
rw [is_o_const_mul_right_iff cne0, is_o_norm_right]
end
end smul_const
section smul
variables [normed_space 𝕜 E'] [normed_space 𝕜 F']
theorem is_O_with.smul {k₁ k₂ : α → 𝕜} (h₁ : is_O_with c k₁ k₂ l) (h₂ : is_O_with c' f' g' l) :
is_O_with (c * c') (λ x, k₁ x • f' x) (λ x, k₂ x • g' x) l :=
by refine ((h₁.norm_norm.mul h₂.norm_norm).congr rfl _ _).of_norm_norm;
by intros; simp only [norm_smul]
theorem is_O.smul {k₁ k₂ : α → 𝕜} (h₁ : is_O k₁ k₂ l) (h₂ : is_O f' g' l) :
is_O (λ x, k₁ x • f' x) (λ x, k₂ x • g' x) l :=
by refine ((h₁.norm_norm.mul h₂.norm_norm).congr _ _).of_norm_norm;
by intros; simp only [norm_smul]
theorem is_O.smul_is_o {k₁ k₂ : α → 𝕜} (h₁ : is_O k₁ k₂ l) (h₂ : is_o f' g' l) :
is_o (λ x, k₁ x • f' x) (λ x, k₂ x • g' x) l :=
by refine ((h₁.norm_norm.mul_is_o h₂.norm_norm).congr _ _).of_norm_norm;
by intros; simp only [norm_smul]
theorem is_o.smul_is_O {k₁ k₂ : α → 𝕜} (h₁ : is_o k₁ k₂ l) (h₂ : is_O f' g' l) :
is_o (λ x, k₁ x • f' x) (λ x, k₂ x • g' x) l :=
by refine ((h₁.norm_norm.mul_is_O h₂.norm_norm).congr _ _).of_norm_norm;
by intros; simp only [norm_smul]
theorem is_o.smul {k₁ k₂ : α → 𝕜} (h₁ : is_o k₁ k₂ l) (h₂ : is_o f' g' l) :
is_o (λ x, k₁ x • f' x) (λ x, k₂ x • g' x) l :=
by refine ((h₁.norm_norm.mul h₂.norm_norm).congr _ _).of_norm_norm;
by intros; simp only [norm_smul]
end smul
/-! ### Sum -/
section sum
variables {ι : Type*} {A : ι → α → E'} {C : ι → ℝ} {s : finset ι}
theorem is_O_with.sum (h : ∀ i ∈ s, is_O_with (C i) (A i) g l) :
is_O_with (∑ i in s, C i) (λ x, ∑ i in s, A i x) g l :=
begin
induction s using finset.induction_on with i s is IH,
{ simp only [is_O_with_zero', finset.sum_empty, forall_true_iff] },
{ simp only [is, finset.sum_insert, not_false_iff],
exact (h _ (finset.mem_insert_self i s)).add (IH (λ j hj, h _ (finset.mem_insert_of_mem hj))) }
end
theorem is_O.sum (h : ∀ i ∈ s, is_O (A i) g l) :
is_O (λ x, ∑ i in s, A i x) g l :=
begin
induction s using finset.induction_on with i s is IH,
{ simp only [is_O_zero, finset.sum_empty, forall_true_iff] },
{ simp only [is, finset.sum_insert, not_false_iff],
exact (h _ (finset.mem_insert_self i s)).add (IH (λ j hj, h _ (finset.mem_insert_of_mem hj))) }
end
theorem is_o.sum (h : ∀ i ∈ s, is_o (A i) g' l) :
is_o (λ x, ∑ i in s, A i x) g' l :=
begin
induction s using finset.induction_on with i s is IH,
{ simp only [is_o_zero, finset.sum_empty, forall_true_iff] },
{ simp only [is, finset.sum_insert, not_false_iff],
exact (h _ (finset.mem_insert_self i s)).add (IH (λ j hj, h _ (finset.mem_insert_of_mem hj))) }
end
end sum
/-! ### Relation between `f = o(g)` and `f / g → 0` -/
theorem is_o.tendsto_div_nhds_zero {f g : α → 𝕜} {l : filter α} (h : is_o f g l) :
tendsto (λ x, f x / (g x)) l (𝓝 0) :=
have eq₁ : is_o (λ x, f x / g x) (λ x, g x / g x) l,
by simpa only [div_eq_mul_inv] using h.mul_is_O (is_O_refl _ _),
have eq₂ : is_O (λ x, g x / g x) (λ x, (1 : 𝕜)) l,
from is_O_of_le _ (λ x, by simp [div_self_le_one]),
(is_o_one_iff 𝕜).mp (eq₁.trans_is_O eq₂)
theorem is_o.tendsto_inv_smul_nhds_zero [normed_space 𝕜 E'] {f : α → E'} {g : α → 𝕜} {l : filter α}
(h : is_o f g l) : tendsto (λ x, (g x)⁻¹ • f x) l (𝓝 0) :=
by simpa only [div_eq_inv_mul, ← norm_inv, ← norm_smul,
← tendsto_zero_iff_norm_tendsto_zero] using h.norm_norm.tendsto_div_nhds_zero
theorem is_o_iff_tendsto' {f g : α → 𝕜} {l : filter α}
(hgf : ∀ᶠ x in l, g x = 0 → f x = 0) :
is_o f g l ↔ tendsto (λ x, f x / (g x)) l (𝓝 0) :=
iff.intro is_o.tendsto_div_nhds_zero $ λ h,
(((is_o_one_iff _).mpr h).mul_is_O (is_O_refl g l)).congr'
(hgf.mono $ λ x, div_mul_cancel_of_imp) (eventually_of_forall $ λ x, one_mul _)
theorem is_o_iff_tendsto {f g : α → 𝕜} {l : filter α}
(hgf : ∀ x, g x = 0 → f x = 0) :
is_o f g l ↔ tendsto (λ x, f x / (g x)) l (𝓝 0) :=
is_o_iff_tendsto' (eventually_of_forall hgf)
alias is_o_iff_tendsto' ↔ _ asymptotics.is_o_of_tendsto'
alias is_o_iff_tendsto ↔ _ asymptotics.is_o_of_tendsto
lemma is_o_const_left_of_ne {c : E''} (hc : c ≠ 0) :
is_o (λ x, c) g l ↔ tendsto (norm ∘ g) l at_top :=
begin
split; intro h,
{ refine (at_top_basis' 1).tendsto_right_iff.2 (λ C hC, _),
replace hC : 0 < C := zero_lt_one.trans_le hC,
replace h : is_o (λ _, 1 : α → ℝ) g l := (is_O_const_const _ hc _).trans_is_o h,
refine (h.def $ inv_pos.2 hC).mono (λ x hx, _),
rwa [norm_one, ← div_eq_inv_mul, one_le_div hC] at hx },
{ suffices : is_o (λ _, 1 : α → ℝ) g l,
from (is_O_const_const c (@one_ne_zero ℝ _ _) _).trans_is_o this,
refine is_o_iff.2 (λ ε ε0, (tendsto_at_top.1 h ε⁻¹).mono (λ x hx, _)),
rwa [norm_one, ← inv_inv ε, ← div_eq_inv_mul, one_le_div (inv_pos.2 ε0)] }
end
@[simp] lemma is_o_const_left {c : E''} :
is_o (λ x, c) g'' l ↔ c = 0 ∨ tendsto (norm ∘ g'') l at_top :=
begin
rcases eq_or_ne c 0 with rfl | hc,
{ simp only [is_o_zero, eq_self_iff_true, true_or] },
{ simp only [hc, false_or, is_o_const_left_of_ne hc] }
end
@[simp] theorem is_o_const_const_iff [ne_bot l] {d : E''} {c : F''} :
is_o (λ x, d) (λ x, c) l ↔ d = 0 :=
have ¬tendsto (function.const α ∥c∥) l at_top,
from not_tendsto_at_top_of_tendsto_nhds tendsto_const_nhds,
by simp [function.const, this]
@[simp] lemma is_o_pure {x} : is_o f'' g'' (pure x) ↔ f'' x = 0 :=
calc is_o f'' g'' (pure x) ↔ is_o (λ y : α, f'' x) (λ _, g'' x) (pure x) : is_o_congr rfl rfl
... ↔ f'' x = 0 : is_o_const_const_iff
lemma is_o_const_id_comap_norm_at_top (c : F'') : is_o (λ x : E'', c) id (comap norm at_top) :=
is_o_const_left.2 $ or.inr tendsto_comap
lemma is_o_const_id_at_top (c : E'') : is_o (λ x : ℝ, c) id at_top :=
is_o_const_left.2 $ or.inr tendsto_abs_at_top_at_top
lemma is_o_const_id_at_bot (c : E'') : is_o (λ x : ℝ, c) id at_bot :=
is_o_const_left.2 $ or.inr tendsto_abs_at_bot_at_top
/-!
### Eventually (u / v) * v = u
If `u` and `v` are linked by an `is_O_with` relation, then we
eventually have `(u / v) * v = u`, even if `v` vanishes.
-/
section eventually_mul_div_cancel
variables {u v : α → 𝕜}
lemma is_O_with.eventually_mul_div_cancel (h : is_O_with c u v l) :
(u / v) * v =ᶠ[l] u :=
eventually.mono h.bound (λ y hy, div_mul_cancel_of_imp $ λ hv, by simpa [hv] using hy)
/-- If `u = O(v)` along `l`, then `(u / v) * v = u` eventually at `l`. -/
lemma is_O.eventually_mul_div_cancel (h : is_O u v l) : (u / v) * v =ᶠ[l] u :=
let ⟨c, hc⟩ := h.is_O_with in hc.eventually_mul_div_cancel
/-- If `u = o(v)` along `l`, then `(u / v) * v = u` eventually at `l`. -/
lemma is_o.eventually_mul_div_cancel (h : is_o u v l) : (u / v) * v =ᶠ[l] u :=
(h.forall_is_O_with zero_lt_one).eventually_mul_div_cancel
end eventually_mul_div_cancel
/-! ### Equivalent definitions of the form `∃ φ, u =ᶠ[l] φ * v` in a `normed_field`. -/
section exists_mul_eq
variables {u v : α → 𝕜}
/-- If `∥φ∥` is eventually bounded by `c`, and `u =ᶠ[l] φ * v`, then we have `is_O_with c u v l`.
This does not require any assumptions on `c`, which is why we keep this version along with
`is_O_with_iff_exists_eq_mul`. -/
lemma is_O_with_of_eq_mul (φ : α → 𝕜) (hφ : ∀ᶠ x in l, ∥φ x∥ ≤ c) (h : u =ᶠ[l] φ * v) :
is_O_with c u v l :=
begin
unfold is_O_with,
refine h.symm.rw (λ x a, ∥a∥ ≤ c * ∥v x∥) (hφ.mono $ λ x hx, _),
simp only [norm_mul, pi.mul_apply],
exact mul_le_mul_of_nonneg_right hx (norm_nonneg _)
end
lemma is_O_with_iff_exists_eq_mul (hc : 0 ≤ c) :
is_O_with c u v l ↔ ∃ (φ : α → 𝕜) (hφ : ∀ᶠ x in l, ∥φ x∥ ≤ c), u =ᶠ[l] φ * v :=
begin
split,
{ intro h,
use (λ x, u x / v x),
refine ⟨eventually.mono h.bound (λ y hy, _), h.eventually_mul_div_cancel.symm⟩,
simpa using div_le_of_nonneg_of_le_mul (norm_nonneg _) hc hy },
{ rintros ⟨φ, hφ, h⟩,
exact is_O_with_of_eq_mul φ hφ h }
end
lemma is_O_with.exists_eq_mul (h : is_O_with c u v l) (hc : 0 ≤ c) :
∃ (φ : α → 𝕜) (hφ : ∀ᶠ x in l, ∥φ x∥ ≤ c), u =ᶠ[l] φ * v :=
(is_O_with_iff_exists_eq_mul hc).mp h
lemma is_O_iff_exists_eq_mul :
is_O u v l ↔ ∃ (φ : α → 𝕜) (hφ : l.is_bounded_under (≤) (norm ∘ φ)), u =ᶠ[l] φ * v :=
begin
split,
{ rintros h,
rcases h.exists_nonneg with ⟨c, hnnc, hc⟩,
rcases hc.exists_eq_mul hnnc with ⟨φ, hφ, huvφ⟩,
exact ⟨φ, ⟨c, hφ⟩, huvφ⟩ },
{ rintros ⟨φ, ⟨c, hφ⟩, huvφ⟩,
exact is_O_iff_is_O_with.2 ⟨c, is_O_with_of_eq_mul φ hφ huvφ⟩ }
end
alias is_O_iff_exists_eq_mul ↔ asymptotics.is_O.exists_eq_mul _
lemma is_o_iff_exists_eq_mul :
is_o u v l ↔ ∃ (φ : α → 𝕜) (hφ : tendsto φ l (𝓝 0)), u =ᶠ[l] φ * v :=
begin
split,
{ exact λ h, ⟨λ x, u x / v x, h.tendsto_div_nhds_zero, h.eventually_mul_div_cancel.symm⟩ },
{ unfold is_o, rintros ⟨φ, hφ, huvφ⟩ c hpos,
rw normed_group.tendsto_nhds_zero at hφ,
exact is_O_with_of_eq_mul _ ((hφ c hpos).mono $ λ x, le_of_lt) huvφ }
end
alias is_o_iff_exists_eq_mul ↔ asymptotics.is_o.exists_eq_mul _
end exists_mul_eq
/-! ### Miscellanous lemmas -/
theorem div_is_bounded_under_of_is_O {α : Type*} {l : filter α}
{f g : α → 𝕜} (h : is_O f g l) :
is_bounded_under (≤) l (λ x, ∥f x / g x∥) :=
begin
obtain ⟨c, hc⟩ := is_O_iff.mp h,
refine ⟨max c 0, eventually_map.2 (filter.mem_of_superset hc (λ x hx, _))⟩,
simp only [mem_set_of_eq, norm_div] at ⊢ hx,
by_cases hgx : g x = 0,
{ rw [hgx, norm_zero, div_zero, le_max_iff],
exact or.inr le_rfl },
{ exact le_max_iff.2 (or.inl ((div_le_iff (norm_pos_iff.2 hgx)).2 hx)) }
end
theorem is_O_iff_div_is_bounded_under {α : Type*} {l : filter α}
{f g : α → 𝕜} (hgf : ∀ᶠ x in l, g x = 0 → f x = 0) :
is_O f g l ↔ is_bounded_under (≤) l (λ x, ∥f x / g x∥) :=
begin
refine ⟨div_is_bounded_under_of_is_O, λ h, _⟩,
obtain ⟨c, hc⟩ := h,
rw filter.eventually_iff at hgf hc,
simp only [mem_set_of_eq, mem_map, norm_div] at hc,
refine is_O_iff.2 ⟨c, filter.eventually_of_mem (inter_mem hgf hc) (λ x hx, _)⟩,
by_cases hgx : g x = 0,
{ simp [hx.1 hgx, hgx] },
{ refine (div_le_iff (norm_pos_iff.2 hgx)).mp hx.2 },
end
theorem is_O_of_div_tendsto_nhds {α : Type*} {l : filter α}
{f g : α → 𝕜} (hgf : ∀ᶠ x in l, g x = 0 → f x = 0)
(c : 𝕜) (H : filter.tendsto (f / g) l (𝓝 c)) :
is_O f g l :=
(is_O_iff_div_is_bounded_under hgf).2 $ H.norm.is_bounded_under_le
lemma is_o.tendsto_zero_of_tendsto {α E 𝕜 : Type*} [normed_group E] [normed_field 𝕜] {u : α → E}
{v : α → 𝕜} {l : filter α} {y : 𝕜} (huv : is_o u v l) (hv : tendsto v l (𝓝 y)) :
tendsto u l (𝓝 0) :=
begin
suffices h : is_o u (λ x, (1 : 𝕜)) l,
{ rwa is_o_one_iff at h },
exact huv.trans_is_O (is_O_one_of_tendsto 𝕜 hv),
end
theorem is_o_pow_pow {m n : ℕ} (h : m < n) :
is_o (λ(x : 𝕜), x^n) (λx, x^m) (𝓝 0) :=
begin
let p := n - m,
have nmp : n = m + p := (add_tsub_cancel_of_le (le_of_lt h)).symm,
have : (λ(x : 𝕜), x^m) = (λx, x^m * 1), by simp only [mul_one],
simp only [this, pow_add, nmp],
refine is_O.mul_is_o (is_O_refl _ _) ((is_o_one_iff _).2 _),
convert (continuous_pow p).tendsto (0 : 𝕜),
exact (zero_pow (tsub_pos_of_lt h)).symm
end
theorem is_o_norm_pow_norm_pow {m n : ℕ} (h : m < n) :
is_o (λ(x : E'), ∥x∥^n) (λx, ∥x∥^m) (𝓝 (0 : E')) :=
(is_o_pow_pow h).comp_tendsto tendsto_norm_zero
theorem is_o_pow_id {n : ℕ} (h : 1 < n) :
is_o (λ(x : 𝕜), x^n) (λx, x) (𝓝 0) :=
by { convert is_o_pow_pow h, simp only [pow_one] }
theorem is_o_norm_pow_id {n : ℕ} (h : 1 < n) :
is_o (λ(x : E'), ∥x∥^n) (λx, x) (𝓝 0) :=
by simpa only [pow_one, is_o_norm_right] using @is_o_norm_pow_norm_pow E' _ _ _ h
theorem is_O_with.right_le_sub_of_lt_1 {f₁ f₂ : α → E'} (h : is_O_with c f₁ f₂ l) (hc : c < 1) :
is_O_with (1 / (1 - c)) f₂ (λx, f₂ x - f₁ x) l :=
is_O_with.of_bound $ mem_of_superset h.bound $ λ x hx,
begin
simp only [mem_set_of_eq] at hx ⊢,
rw [mul_comm, one_div, ← div_eq_mul_inv, le_div_iff, mul_sub, mul_one, mul_comm],
{ exact le_trans (sub_le_sub_left hx _) (norm_sub_norm_le _ _) },
{ exact sub_pos.2 hc }
end
theorem is_O_with.right_le_add_of_lt_1 {f₁ f₂ : α → E'} (h : is_O_with c f₁ f₂ l) (hc : c < 1) :
is_O_with (1 / (1 - c)) f₂ (λx, f₁ x + f₂ x) l :=
(h.neg_right.right_le_sub_of_lt_1 hc).neg_right.of_neg_left.congr rfl (λ x, rfl)
(λ x, by rw [neg_sub, sub_neg_eq_add])
theorem is_o.right_is_O_sub {f₁ f₂ : α → E'} (h : is_o f₁ f₂ l) :
is_O f₂ (λx, f₂ x - f₁ x) l :=
((h.def' one_half_pos).right_le_sub_of_lt_1 one_half_lt_one).is_O
theorem is_o.right_is_O_add {f₁ f₂ : α → E'} (h : is_o f₁ f₂ l) :
is_O f₂ (λx, f₁ x + f₂ x) l :=
((h.def' one_half_pos).right_le_add_of_lt_1 one_half_lt_one).is_O
/-- If `f x = O(g x)` along `cofinite`, then there exists a positive constant `C` such that
`∥f x∥ ≤ C * ∥g x∥` whenever `g x ≠ 0`. -/
theorem bound_of_is_O_cofinite (h : is_O f g'' cofinite) :
∃ C > 0, ∀ ⦃x⦄, g'' x ≠ 0 → ∥f x∥ ≤ C * ∥g'' x∥ :=
begin
rcases h.exists_pos with ⟨C, C₀, hC⟩,
rw [is_O_with, eventually_cofinite] at hC,
rcases (hC.to_finset.image (λ x, ∥f x∥ / ∥g'' x∥)).exists_le with ⟨C', hC'⟩,
have : ∀ x, C * ∥g'' x∥ < ∥f x∥ → ∥f x∥ / ∥g'' x∥ ≤ C', by simpa using hC',
refine ⟨max C C', lt_max_iff.2 (or.inl C₀), λ x h₀, _⟩,
rw [max_mul_of_nonneg _ _ (norm_nonneg _), le_max_iff, or_iff_not_imp_left, not_le],
exact λ hx, (div_le_iff (norm_pos_iff.2 h₀)).1 (this _ hx)
end
theorem is_O_cofinite_iff (h : ∀ x, g'' x = 0 → f'' x = 0) :
is_O f'' g'' cofinite ↔ ∃ C, ∀ x, ∥f'' x∥ ≤ C * ∥g'' x∥ :=
⟨λ h', let ⟨C, C₀, hC⟩ := bound_of_is_O_cofinite h' in
⟨C, λ x, if hx : g'' x = 0 then by simp [h _ hx, hx] else hC hx⟩,
λ h, (is_O_top.2 h).mono le_top⟩
theorem bound_of_is_O_nat_at_top {f : ℕ → E} {g'' : ℕ → E''} (h : is_O f g'' at_top) :
∃ C > 0, ∀ ⦃x⦄, g'' x ≠ 0 → ∥f x∥ ≤ C * ∥g'' x∥ :=
bound_of_is_O_cofinite $ by rwa nat.cofinite_eq_at_top
theorem is_O_nat_at_top_iff {f : ℕ → E''} {g : ℕ → F''} (h : ∀ x, g x = 0 → f x = 0) :
is_O f g at_top ↔ ∃ C, ∀ x, ∥f x∥ ≤ C * ∥g x∥ :=
by rw [← nat.cofinite_eq_at_top, is_O_cofinite_iff h]
theorem is_O_one_nat_at_top_iff {f : ℕ → E''} :
is_O f (λ n, 1 : ℕ → ℝ) at_top ↔ ∃ C, ∀ n, ∥f n∥ ≤ C :=
iff.trans (is_O_nat_at_top_iff (λ n h, (one_ne_zero h).elim)) $
by simp only [norm_one, mul_one]
theorem is_O_with_pi {ι : Type*} [fintype ι] {E' : ι → Type*} [Π i, normed_group (E' i)]
{f : α → Π i, E' i} {C : ℝ} (hC : 0 ≤ C) :
is_O_with C f g' l ↔ ∀ i, is_O_with C (λ x, f x i) g' l :=
have ∀ x, 0 ≤ C * ∥g' x∥, from λ x, mul_nonneg hC (norm_nonneg _),
by simp only [is_O_with_iff, pi_norm_le_iff (this _), eventually_all]
@[simp] theorem is_O_pi {ι : Type*} [fintype ι] {E' : ι → Type*} [Π i, normed_group (E' i)]
{f : α → Π i, E' i} :
is_O f g' l ↔ ∀ i, is_O (λ x, f x i) g' l :=
begin
simp only [is_O_iff_eventually_is_O_with, ← eventually_all],
exact eventually_congr (eventually_at_top.2 ⟨0, λ c, is_O_with_pi⟩)
end
@[simp] theorem is_o_pi {ι : Type*} [fintype ι] {E' : ι → Type*} [Π i, normed_group (E' i)]
{f : α → Π i, E' i} :
is_o f g' l ↔ ∀ i, is_o (λ x, f x i) g' l :=
begin
simp only [is_o, is_O_with_pi, le_of_lt] { contextual := tt },
exact ⟨λ h i c hc, h hc i, λ h c hc i, h i hc⟩
end
end asymptotics
open asymptotics
lemma summable_of_is_O {ι E} [normed_group E] [complete_space E] {f : ι → E} {g : ι → ℝ}
(hg : summable g) (h : is_O f g cofinite) : summable f :=
let ⟨C, hC⟩ := h.is_O_with in
summable_of_norm_bounded_eventually (λ x, C * ∥g x∥) (hg.abs.mul_left _) hC.bound
lemma summable_of_is_O_nat {E} [normed_group E] [complete_space E] {f : ℕ → E} {g : ℕ → ℝ}
(hg : summable g) (h : is_O f g at_top) : summable f :=
summable_of_is_O hg $ nat.cofinite_eq_at_top.symm ▸ h
namespace local_homeomorph
variables {α : Type*} {β : Type*} [topological_space α] [topological_space β]
variables {E : Type*} [has_norm E] {F : Type*} [has_norm F]
/-- Transfer `is_O_with` over a `local_homeomorph`. -/
lemma is_O_with_congr (e : local_homeomorph α β) {b : β} (hb : b ∈ e.target)
{f : β → E} {g : β → F} {C : ℝ} :
is_O_with C f g (𝓝 b) ↔ is_O_with C (f ∘ e) (g ∘ e) (𝓝 (e.symm b)) :=
⟨λ h, h.comp_tendsto $
by { convert e.continuous_at (e.map_target hb), exact (e.right_inv hb).symm },
λ h, (h.comp_tendsto (e.continuous_at_symm hb)).congr' rfl
((e.eventually_right_inverse hb).mono $ λ x hx, congr_arg f hx)
((e.eventually_right_inverse hb).mono $ λ x hx, congr_arg g hx)⟩
/-- Transfer `is_O` over a `local_homeomorph`. -/
lemma is_O_congr (e : local_homeomorph α β) {b : β} (hb : b ∈ e.target) {f : β → E} {g : β → F} :
is_O f g (𝓝 b) ↔ is_O (f ∘ e) (g ∘ e) (𝓝 (e.symm b)) :=
by { unfold is_O, exact exists_congr (λ C, e.is_O_with_congr hb) }
/-- Transfer `is_o` over a `local_homeomorph`. -/
lemma is_o_congr (e : local_homeomorph α β) {b : β} (hb : b ∈ e.target) {f : β → E} {g : β → F} :
is_o f g (𝓝 b) ↔ is_o (f ∘ e) (g ∘ e) (𝓝 (e.symm b)) :=
by { unfold is_o, exact forall₂_congr (λ c hc, e.is_O_with_congr hb) }
end local_homeomorph
namespace homeomorph
variables {α : Type*} {β : Type*} [topological_space α] [topological_space β]
variables {E : Type*} [has_norm E] {F : Type*} [has_norm F]
open asymptotics
/-- Transfer `is_O_with` over a `homeomorph`. -/
lemma is_O_with_congr (e : α ≃ₜ β) {b : β} {f : β → E} {g : β → F} {C : ℝ} :
is_O_with C f g (𝓝 b) ↔ is_O_with C (f ∘ e) (g ∘ e) (𝓝 (e.symm b)) :=
e.to_local_homeomorph.is_O_with_congr trivial
/-- Transfer `is_O` over a `homeomorph`. -/
lemma is_O_congr (e : α ≃ₜ β) {b : β} {f : β → E} {g : β → F} :
is_O f g (𝓝 b) ↔ is_O (f ∘ e) (g ∘ e) (𝓝 (e.symm b)) :=
by { unfold is_O, exact exists_congr (λ C, e.is_O_with_congr) }
/-- Transfer `is_o` over a `homeomorph`. -/
lemma is_o_congr (e : α ≃ₜ β) {b : β} {f : β → E} {g : β → F} :
is_o f g (𝓝 b) ↔ is_o (f ∘ e) (g ∘ e) (𝓝 (e.symm b)) :=
by { unfold is_o, exact forall₂_congr (λ c hc, e.is_O_with_congr) }
end homeomorph
|
054ad7794744c422e74b56359068ec41a7f68bb1 | 947fa6c38e48771ae886239b4edce6db6e18d0fb | /src/order/upper_lower.lean | abb12e02c4aedcc1b0ad90ca0baa12a567050caf | [
"Apache-2.0"
] | permissive | ramonfmir/mathlib | c5dc8b33155473fab97c38bd3aa6723dc289beaa | 14c52e990c17f5a00c0cc9e09847af16fabbed25 | refs/heads/master | 1,661,979,343,526 | 1,660,830,384,000 | 1,660,830,384,000 | 182,072,989 | 0 | 0 | null | 1,555,585,876,000 | 1,555,585,876,000 | null | UTF-8 | Lean | false | false | 29,968 | lean | /-
Copyright (c) 2022 Yaël Dillies, Sara Rousta. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies, Sara Rousta
-/
import data.set_like.basic
import data.set.intervals.ord_connected
import order.hom.complete_lattice
/-!
# Up-sets and down-sets
This file defines upper and lower sets in an order.
## Main declarations
* `is_upper_set`: Predicate for a set to be an upper set. This means every element greater than a
member of the set is in the set itself.
* `is_lower_set`: Predicate for a set to be a lower set. This means every element less than a member
of the set is in the set itself.
* `upper_set`: The type of upper sets.
* `lower_set`: The type of lower sets.
* `upper_closure`: The greatest upper set containing a set.
* `lower_closure`: The least lower set containing a set.
* `upper_set.Ici`: Principal upper set. `set.Ici` as an upper set.
* `upper_set.Ioi`: Strict principal upper set. `set.Ioi` as an upper set.
* `lower_set.Iic`: Principal lower set. `set.Iic` as an lower set.
* `lower_set.Iio`: Strict principal lower set. `set.Iio` as an lower set.
## Notes
Upper sets are ordered by **reverse** inclusion. This convention is motivated by the fact that this
makes them order-isomorphic to lower sets and antichains, and matches the convention on `filter`.
## TODO
Lattice structure on antichains. Order equivalence between upper/lower sets and antichains.
-/
open order_dual set
variables {α : Type*} {ι : Sort*} {κ : ι → Sort*}
/-! ### Unbundled upper/lower sets -/
section has_le
variables [has_le α] {s t : set α}
/-- An upper set in an order `α` is a set such that any element greater than one of its members is
also a member. Also called up-set, upward-closed set. -/
def is_upper_set (s : set α) : Prop := ∀ ⦃a b : α⦄, a ≤ b → a ∈ s → b ∈ s
/-- A lower set in an order `α` is a set such that any element less than one of its members is also
a member. Also called down-set, downward-closed set. -/
def is_lower_set (s : set α) : Prop := ∀ ⦃a b : α⦄, b ≤ a → a ∈ s → b ∈ s
lemma is_upper_set_empty : is_upper_set (∅ : set α) := λ _ _ _, id
lemma is_lower_set_empty : is_lower_set (∅ : set α) := λ _ _ _, id
lemma is_upper_set_univ : is_upper_set (univ : set α) := λ _ _ _, id
lemma is_lower_set_univ : is_lower_set (univ : set α) := λ _ _ _, id
lemma is_upper_set.compl (hs : is_upper_set s) : is_lower_set sᶜ := λ a b h hb ha, hb $ hs h ha
lemma is_lower_set.compl (hs : is_lower_set s) : is_upper_set sᶜ := λ a b h hb ha, hb $ hs h ha
@[simp] lemma is_upper_set_compl : is_upper_set sᶜ ↔ is_lower_set s :=
⟨λ h, by { convert h.compl, rw compl_compl }, is_lower_set.compl⟩
@[simp] lemma is_lower_set_compl : is_lower_set sᶜ ↔ is_upper_set s :=
⟨λ h, by { convert h.compl, rw compl_compl }, is_upper_set.compl⟩
lemma is_upper_set.union (hs : is_upper_set s) (ht : is_upper_set t) : is_upper_set (s ∪ t) :=
λ a b h, or.imp (hs h) (ht h)
lemma is_lower_set.union (hs : is_lower_set s) (ht : is_lower_set t) : is_lower_set (s ∪ t) :=
λ a b h, or.imp (hs h) (ht h)
lemma is_upper_set.inter (hs : is_upper_set s) (ht : is_upper_set t) : is_upper_set (s ∩ t) :=
λ a b h, and.imp (hs h) (ht h)
lemma is_lower_set.inter (hs : is_lower_set s) (ht : is_lower_set t) : is_lower_set (s ∩ t) :=
λ a b h, and.imp (hs h) (ht h)
lemma is_upper_set_Union {f : ι → set α} (hf : ∀ i, is_upper_set (f i)) : is_upper_set (⋃ i, f i) :=
λ a b h, Exists₂.imp $ forall_range_iff.2 $ λ i, hf i h
lemma is_lower_set_Union {f : ι → set α} (hf : ∀ i, is_lower_set (f i)) : is_lower_set (⋃ i, f i) :=
λ a b h, Exists₂.imp $ forall_range_iff.2 $ λ i, hf i h
lemma is_upper_set_Union₂ {f : Π i, κ i → set α} (hf : ∀ i j, is_upper_set (f i j)) :
is_upper_set (⋃ i j, f i j) :=
is_upper_set_Union $ λ i, is_upper_set_Union $ hf i
lemma is_lower_set_Union₂ {f : Π i, κ i → set α} (hf : ∀ i j, is_lower_set (f i j)) :
is_lower_set (⋃ i j, f i j) :=
is_lower_set_Union $ λ i, is_lower_set_Union $ hf i
lemma is_upper_set_sUnion {S : set (set α)} (hf : ∀ s ∈ S, is_upper_set s) : is_upper_set (⋃₀ S) :=
λ a b h, Exists₂.imp $ λ s hs, hf s hs h
lemma is_lower_set_sUnion {S : set (set α)} (hf : ∀ s ∈ S, is_lower_set s) : is_lower_set (⋃₀ S) :=
λ a b h, Exists₂.imp $ λ s hs, hf s hs h
lemma is_upper_set_Inter {f : ι → set α} (hf : ∀ i, is_upper_set (f i)) : is_upper_set (⋂ i, f i) :=
λ a b h, forall₂_imp $ forall_range_iff.2 $ λ i, hf i h
lemma is_lower_set_Inter {f : ι → set α} (hf : ∀ i, is_lower_set (f i)) : is_lower_set (⋂ i, f i) :=
λ a b h, forall₂_imp $ forall_range_iff.2 $ λ i, hf i h
lemma is_upper_set_Inter₂ {f : Π i, κ i → set α} (hf : ∀ i j, is_upper_set (f i j)) :
is_upper_set (⋂ i j, f i j) :=
is_upper_set_Inter $ λ i, is_upper_set_Inter $ hf i
lemma is_lower_set_Inter₂ {f : Π i, κ i → set α} (hf : ∀ i j, is_lower_set (f i j)) :
is_lower_set (⋂ i j, f i j) :=
is_lower_set_Inter $ λ i, is_lower_set_Inter $ hf i
lemma is_upper_set_sInter {S : set (set α)} (hf : ∀ s ∈ S, is_upper_set s) : is_upper_set (⋂₀ S) :=
λ a b h, forall₂_imp $ λ s hs, hf s hs h
lemma is_lower_set_sInter {S : set (set α)} (hf : ∀ s ∈ S, is_lower_set s) : is_lower_set (⋂₀ S) :=
λ a b h, forall₂_imp $ λ s hs, hf s hs h
@[simp] lemma is_lower_set_preimage_of_dual_iff : is_lower_set (of_dual ⁻¹' s) ↔ is_upper_set s :=
iff.rfl
@[simp] lemma is_upper_set_preimage_of_dual_iff : is_upper_set (of_dual ⁻¹' s) ↔ is_lower_set s :=
iff.rfl
@[simp] lemma is_lower_set_preimage_to_dual_iff {s : set αᵒᵈ} :
is_lower_set (to_dual ⁻¹' s) ↔ is_upper_set s := iff.rfl
@[simp] lemma is_upper_set_preimage_to_dual_iff {s : set αᵒᵈ} :
is_upper_set (to_dual ⁻¹' s) ↔ is_lower_set s := iff.rfl
alias is_lower_set_preimage_of_dual_iff ↔ _ is_upper_set.of_dual
alias is_upper_set_preimage_of_dual_iff ↔ _ is_lower_set.of_dual
alias is_lower_set_preimage_to_dual_iff ↔ _ is_upper_set.to_dual
alias is_upper_set_preimage_to_dual_iff ↔ _ is_lower_set.to_dual
end has_le
section preorder
variables [preorder α] {s : set α} (a : α)
lemma is_upper_set_Ici : is_upper_set (Ici a) := λ _ _, ge_trans
lemma is_lower_set_Iic : is_lower_set (Iic a) := λ _ _, le_trans
lemma is_upper_set_Ioi : is_upper_set (Ioi a) := λ _ _, flip lt_of_lt_of_le
lemma is_lower_set_Iio : is_lower_set (Iio a) := λ _ _, lt_of_le_of_lt
lemma is_upper_set_iff_Ici_subset : is_upper_set s ↔ ∀ ⦃a⦄, a ∈ s → Ici a ⊆ s :=
by simp [is_upper_set, subset_def, @forall_swap (_ ∈ s)]
lemma is_lower_set_iff_Iic_subset : is_lower_set s ↔ ∀ ⦃a⦄, a ∈ s → Iic a ⊆ s :=
by simp [is_lower_set, subset_def, @forall_swap (_ ∈ s)]
alias is_upper_set_iff_Ici_subset ↔ is_upper_set.Ici_subset _
alias is_lower_set_iff_Iic_subset ↔ is_lower_set.Iic_subset _
lemma is_upper_set.ord_connected (h : is_upper_set s) : s.ord_connected :=
⟨λ a ha b _, Icc_subset_Ici_self.trans $ h.Ici_subset ha⟩
lemma is_lower_set.ord_connected (h : is_lower_set s) : s.ord_connected :=
⟨λ a _ b hb, Icc_subset_Iic_self.trans $ h.Iic_subset hb⟩
section order_top
variables [order_top α]
lemma is_lower_set.top_mem (hs : is_lower_set s) : ⊤ ∈ s ↔ s = univ :=
⟨λ h, eq_univ_of_forall $ λ a, hs le_top h, λ h, h.symm ▸ mem_univ _⟩
lemma is_upper_set.top_mem (hs : is_upper_set s) : ⊤ ∈ s ↔ s.nonempty :=
⟨λ h, ⟨_, h⟩, λ ⟨a, ha⟩, hs le_top ha⟩
lemma is_upper_set.not_top_mem (hs : is_upper_set s) : ⊤ ∉ s ↔ s = ∅ :=
hs.top_mem.not.trans not_nonempty_iff_eq_empty
end order_top
section order_bot
variables [order_bot α]
lemma is_upper_set.bot_mem (hs : is_upper_set s) : ⊥ ∈ s ↔ s = univ :=
⟨λ h, eq_univ_of_forall $ λ a, hs bot_le h, λ h, h.symm ▸ mem_univ _⟩
lemma is_lower_set.bot_mem (hs : is_lower_set s) : ⊥ ∈ s ↔ s.nonempty :=
⟨λ h, ⟨_, h⟩, λ ⟨a, ha⟩, hs bot_le ha⟩
lemma is_lower_set.not_bot_mem (hs : is_lower_set s) : ⊥ ∉ s ↔ s = ∅ :=
hs.bot_mem.not.trans not_nonempty_iff_eq_empty
end order_bot
end preorder
/-! ### Bundled upper/lower sets -/
section has_le
variables [has_le α]
/-- The type of upper sets of an order. -/
structure upper_set (α : Type*) [has_le α] :=
(carrier : set α)
(upper' : is_upper_set carrier)
/-- The type of lower sets of an order. -/
structure lower_set (α : Type*) [has_le α] :=
(carrier : set α)
(lower' : is_lower_set carrier)
namespace upper_set
instance : set_like (upper_set α) α :=
{ coe := upper_set.carrier,
coe_injective' := λ s t h, by { cases s, cases t, congr' } }
@[ext] lemma ext {s t : upper_set α} : (s : set α) = t → s = t := set_like.ext'
@[simp] lemma carrier_eq_coe (s : upper_set α) : s.carrier = s := rfl
protected lemma upper (s : upper_set α) : is_upper_set (s : set α) := s.upper'
end upper_set
namespace lower_set
instance : set_like (lower_set α) α :=
{ coe := lower_set.carrier,
coe_injective' := λ s t h, by { cases s, cases t, congr' } }
@[ext] lemma ext {s t : lower_set α} : (s : set α) = t → s = t := set_like.ext'
@[simp] lemma carrier_eq_coe (s : lower_set α) : s.carrier = s := rfl
protected lemma lower (s : lower_set α) : is_lower_set (s : set α) := s.lower'
end lower_set
/-! #### Order -/
namespace upper_set
variables {S : set (upper_set α)} {s t : upper_set α} {a : α}
instance : has_sup (upper_set α) := ⟨λ s t, ⟨s ∩ t, s.upper.inter t.upper⟩⟩
instance : has_inf (upper_set α) := ⟨λ s t, ⟨s ∪ t, s.upper.union t.upper⟩⟩
instance : has_top (upper_set α) := ⟨⟨∅, is_upper_set_empty⟩⟩
instance : has_bot (upper_set α) := ⟨⟨univ, is_upper_set_univ⟩⟩
instance : has_Sup (upper_set α) :=
⟨λ S, ⟨⋂ s ∈ S, ↑s, is_upper_set_Inter₂ $ λ s _, s.upper⟩⟩
instance : has_Inf (upper_set α) :=
⟨λ S, ⟨⋃ s ∈ S, ↑s, is_upper_set_Union₂ $ λ s _, s.upper⟩⟩
instance : complete_distrib_lattice (upper_set α) :=
(to_dual.injective.comp $ set_like.coe_injective).complete_distrib_lattice _
(λ _ _, rfl) (λ _ _, rfl) (λ _, rfl) (λ _, rfl) rfl rfl
instance : inhabited (upper_set α) := ⟨⊥⟩
@[simp, norm_cast] lemma coe_subset_coe : (s : set α) ⊆ t ↔ t ≤ s := iff.rfl
@[simp, norm_cast] lemma coe_top : ((⊤ : upper_set α) : set α) = ∅ := rfl
@[simp, norm_cast] lemma coe_bot : ((⊥ : upper_set α) : set α) = univ := rfl
@[simp, norm_cast] lemma coe_sup (s t : upper_set α) : (↑(s ⊔ t) : set α) = s ∩ t := rfl
@[simp, norm_cast] lemma coe_inf (s t : upper_set α) : (↑(s ⊓ t) : set α) = s ∪ t := rfl
@[simp, norm_cast] lemma coe_Sup (S : set (upper_set α)) : (↑(Sup S) : set α) = ⋂ s ∈ S, ↑s := rfl
@[simp, norm_cast] lemma coe_Inf (S : set (upper_set α)) : (↑(Inf S) : set α) = ⋃ s ∈ S, ↑s := rfl
@[simp, norm_cast] lemma coe_supr (f : ι → upper_set α) : (↑(⨆ i, f i) : set α) = ⋂ i, f i :=
by simp [supr]
@[simp, norm_cast] lemma coe_infi (f : ι → upper_set α) : (↑(⨅ i, f i) : set α) = ⋃ i, f i :=
by simp [infi]
@[simp, norm_cast] lemma coe_supr₂ (f : Π i, κ i → upper_set α) :
(↑(⨆ i j, f i j) : set α) = ⋂ i j, f i j := by simp_rw coe_supr
@[simp, norm_cast] lemma coe_infi₂ (f : Π i, κ i → upper_set α) :
(↑(⨅ i j, f i j) : set α) = ⋃ i j, f i j := by simp_rw coe_infi
@[simp] lemma not_mem_top : a ∉ (⊤ : upper_set α) := id
@[simp] lemma mem_bot : a ∈ (⊥ : upper_set α) := trivial
@[simp] lemma mem_sup_iff : a ∈ s ⊔ t ↔ a ∈ s ∧ a ∈ t := iff.rfl
@[simp] lemma mem_inf_iff : a ∈ s ⊓ t ↔ a ∈ s ∨ a ∈ t := iff.rfl
@[simp] lemma mem_Sup_iff : a ∈ Sup S ↔ ∀ s ∈ S, a ∈ s := mem_Inter₂
@[simp] lemma mem_Inf_iff : a ∈ Inf S ↔ ∃ s ∈ S, a ∈ s := mem_Union₂
@[simp] lemma mem_supr_iff {f : ι → upper_set α} : a ∈ (⨆ i, f i) ↔ ∀ i, a ∈ f i :=
by { rw [←set_like.mem_coe, coe_supr], exact mem_Inter }
@[simp] lemma mem_infi_iff {f : ι → upper_set α} : a ∈ (⨅ i, f i) ↔ ∃ i, a ∈ f i :=
by { rw [←set_like.mem_coe, coe_infi], exact mem_Union }
@[simp] lemma mem_supr₂_iff {f : Π i, κ i → upper_set α} : a ∈ (⨆ i j, f i j) ↔ ∀ i j, a ∈ f i j :=
by simp_rw mem_supr_iff
@[simp] lemma mem_infi₂_iff {f : Π i, κ i → upper_set α} : a ∈ (⨅ i j, f i j) ↔ ∃ i j, a ∈ f i j :=
by simp_rw mem_infi_iff
end upper_set
namespace lower_set
variables {S : set (lower_set α)} {s t : lower_set α} {a : α}
instance : has_sup (lower_set α) := ⟨λ s t, ⟨s ∪ t, λ a b h, or.imp (s.lower h) (t.lower h)⟩⟩
instance : has_inf (lower_set α) := ⟨λ s t, ⟨s ∩ t, λ a b h, and.imp (s.lower h) (t.lower h)⟩⟩
instance : has_top (lower_set α) := ⟨⟨univ, λ a b h, id⟩⟩
instance : has_bot (lower_set α) := ⟨⟨∅, λ a b h, id⟩⟩
instance : has_Sup (lower_set α) := ⟨λ S, ⟨⋃ s ∈ S, ↑s, is_lower_set_Union₂ $ λ s _, s.lower⟩⟩
instance : has_Inf (lower_set α) := ⟨λ S, ⟨⋂ s ∈ S, ↑s, is_lower_set_Inter₂ $ λ s _, s.lower⟩⟩
instance : complete_distrib_lattice (lower_set α) :=
set_like.coe_injective.complete_distrib_lattice _
(λ _ _, rfl) (λ _ _, rfl) (λ _, rfl) (λ _, rfl) rfl rfl
instance : inhabited (lower_set α) := ⟨⊥⟩
@[simp, norm_cast] lemma coe_subset_coe : (s : set α) ⊆ t ↔ s ≤ t := iff.rfl
@[simp, norm_cast] lemma coe_top : ((⊤ : lower_set α) : set α) = univ := rfl
@[simp, norm_cast] lemma coe_bot : ((⊥ : lower_set α) : set α) = ∅ := rfl
@[simp, norm_cast] lemma coe_sup (s t : lower_set α) : (↑(s ⊔ t) : set α) = s ∪ t := rfl
@[simp, norm_cast] lemma coe_inf (s t : lower_set α) : (↑(s ⊓ t) : set α) = s ∩ t := rfl
@[simp, norm_cast] lemma coe_Sup (S : set (lower_set α)) : (↑(Sup S) : set α) = ⋃ s ∈ S, ↑s := rfl
@[simp, norm_cast] lemma coe_Inf (S : set (lower_set α)) : (↑(Inf S) : set α) = ⋂ s ∈ S, ↑s := rfl
@[simp, norm_cast] lemma coe_supr (f : ι → lower_set α) : (↑(⨆ i, f i) : set α) = ⋃ i, f i :=
by simp_rw [supr, coe_Sup, mem_range, Union_exists, Union_Union_eq']
@[simp, norm_cast] lemma coe_infi (f : ι → lower_set α) : (↑(⨅ i, f i) : set α) = ⋂ i, f i :=
by simp_rw [infi, coe_Inf, mem_range, Inter_exists, Inter_Inter_eq']
@[simp, norm_cast] lemma coe_supr₂ (f : Π i, κ i → lower_set α) :
(↑(⨆ i j, f i j) : set α) = ⋃ i j, f i j := by simp_rw coe_supr
@[simp, norm_cast] lemma coe_infi₂ (f : Π i, κ i → lower_set α) :
(↑(⨅ i j, f i j) : set α) = ⋂ i j, f i j := by simp_rw coe_infi
@[simp] lemma mem_top : a ∈ (⊤ : lower_set α) := trivial
@[simp] lemma not_mem_bot : a ∉ (⊥ : lower_set α) := id
@[simp] lemma mem_sup_iff : a ∈ s ⊔ t ↔ a ∈ s ∨ a ∈ t := iff.rfl
@[simp] lemma mem_inf_iff : a ∈ s ⊓ t ↔ a ∈ s ∧ a ∈ t := iff.rfl
@[simp] lemma mem_Sup_iff : a ∈ Sup S ↔ ∃ s ∈ S, a ∈ s := mem_Union₂
@[simp] lemma mem_Inf_iff : a ∈ Inf S ↔ ∀ s ∈ S, a ∈ s := mem_Inter₂
@[simp] lemma mem_supr_iff {f : ι → lower_set α} : a ∈ (⨆ i, f i) ↔ ∃ i, a ∈ f i :=
by { rw [←set_like.mem_coe, coe_supr], exact mem_Union }
@[simp] lemma mem_infi_iff {f : ι → lower_set α} : a ∈ (⨅ i, f i) ↔ ∀ i, a ∈ f i :=
by { rw [←set_like.mem_coe, coe_infi], exact mem_Inter }
@[simp] lemma mem_supr₂_iff {f : Π i, κ i → lower_set α} : a ∈ (⨆ i j, f i j) ↔ ∃ i j, a ∈ f i j :=
by simp_rw mem_supr_iff
@[simp] lemma mem_infi₂_iff {f : Π i, κ i → lower_set α} : a ∈ (⨅ i j, f i j) ↔ ∀ i j, a ∈ f i j :=
by simp_rw mem_infi_iff
end lower_set
/-! #### Complement -/
/-- The complement of a lower set as an upper set. -/
def upper_set.compl (s : upper_set α) : lower_set α := ⟨sᶜ, s.upper.compl⟩
/-- The complement of a lower set as an upper set. -/
def lower_set.compl (s : lower_set α) : upper_set α := ⟨sᶜ, s.lower.compl⟩
namespace upper_set
variables {s t : upper_set α} {a : α}
@[simp] lemma coe_compl (s : upper_set α) : (s.compl : set α) = sᶜ := rfl
@[simp] lemma mem_compl_iff : a ∈ s.compl ↔ a ∉ s := iff.rfl
@[simp] lemma compl_compl (s : upper_set α) : s.compl.compl = s := upper_set.ext $ compl_compl _
@[simp] lemma compl_le_compl : s.compl ≤ t.compl ↔ s ≤ t := compl_subset_compl
@[simp] protected lemma compl_sup (s t : upper_set α) : (s ⊔ t).compl = s.compl ⊔ t.compl :=
lower_set.ext compl_inf
@[simp] protected lemma compl_inf (s t : upper_set α) : (s ⊓ t).compl = s.compl ⊓ t.compl :=
lower_set.ext compl_sup
@[simp] protected lemma compl_top : (⊤ : upper_set α).compl = ⊤ := lower_set.ext compl_empty
@[simp] protected lemma compl_bot : (⊥ : upper_set α).compl = ⊥ := lower_set.ext compl_univ
@[simp] protected lemma compl_Sup (S : set (upper_set α)) :
(Sup S).compl = ⨆ s ∈ S, upper_set.compl s :=
lower_set.ext $ by simp only [coe_compl, coe_Sup, compl_Inter₂, lower_set.coe_supr₂]
@[simp] protected lemma compl_Inf (S : set (upper_set α)) :
(Inf S).compl = ⨅ s ∈ S, upper_set.compl s :=
lower_set.ext $ by simp only [coe_compl, coe_Inf, compl_Union₂, lower_set.coe_infi₂]
@[simp] protected lemma compl_supr (f : ι → upper_set α) : (⨆ i, f i).compl = ⨆ i, (f i).compl :=
lower_set.ext $ by simp only [coe_compl, coe_supr, compl_Inter, lower_set.coe_supr]
@[simp] protected lemma compl_infi (f : ι → upper_set α) : (⨅ i, f i).compl = ⨅ i, (f i).compl :=
lower_set.ext $ by simp only [coe_compl, coe_infi, compl_Union, lower_set.coe_infi]
@[simp] lemma compl_supr₂ (f : Π i, κ i → upper_set α) :
(⨆ i j, f i j).compl = ⨆ i j, (f i j).compl :=
by simp_rw upper_set.compl_supr
@[simp] lemma compl_infi₂ (f : Π i, κ i → upper_set α) :
(⨅ i j, f i j).compl = ⨅ i j, (f i j).compl :=
by simp_rw upper_set.compl_infi
end upper_set
namespace lower_set
variables {s t : lower_set α} {a : α}
@[simp] lemma coe_compl (s : lower_set α) : (s.compl : set α) = sᶜ := rfl
@[simp] lemma mem_compl_iff : a ∈ s.compl ↔ a ∉ s := iff.rfl
@[simp] lemma compl_compl (s : lower_set α) : s.compl.compl = s := lower_set.ext $ compl_compl _
@[simp] lemma compl_le_compl : s.compl ≤ t.compl ↔ s ≤ t := compl_subset_compl
protected lemma compl_sup (s t : lower_set α) : (s ⊔ t).compl = s.compl ⊔ t.compl :=
upper_set.ext compl_sup
protected lemma compl_inf (s t : lower_set α) : (s ⊓ t).compl = s.compl ⊓ t.compl :=
upper_set.ext compl_inf
protected lemma compl_top : (⊤ : lower_set α).compl = ⊤ := upper_set.ext compl_univ
protected lemma compl_bot : (⊥ : lower_set α).compl = ⊥ := upper_set.ext compl_empty
protected lemma compl_Sup (S : set (lower_set α)) : (Sup S).compl = ⨆ s ∈ S, lower_set.compl s :=
upper_set.ext $ by simp only [coe_compl, coe_Sup, compl_Union₂, upper_set.coe_supr₂]
protected lemma compl_Inf (S : set (lower_set α)) : (Inf S).compl = ⨅ s ∈ S, lower_set.compl s :=
upper_set.ext $ by simp only [coe_compl, coe_Inf, compl_Inter₂, upper_set.coe_infi₂]
protected lemma compl_supr (f : ι → lower_set α) : (⨆ i, f i).compl = ⨆ i, (f i).compl :=
upper_set.ext $ by simp only [coe_compl, coe_supr, compl_Union, upper_set.coe_supr]
protected lemma compl_infi (f : ι → lower_set α) : (⨅ i, f i).compl = ⨅ i, (f i).compl :=
upper_set.ext $ by simp only [coe_compl, coe_infi, compl_Inter, upper_set.coe_infi]
@[simp] lemma compl_supr₂ (f : Π i, κ i → lower_set α) :
(⨆ i j, f i j).compl = ⨆ i j, (f i j).compl :=
by simp_rw lower_set.compl_supr
@[simp] lemma compl_infi₂ (f : Π i, κ i → lower_set α) :
(⨅ i j, f i j).compl = ⨅ i j, (f i j).compl :=
by simp_rw lower_set.compl_infi
end lower_set
/-- Upper sets are order-isomorphic to lower sets under complementation. -/
@[simps] def upper_set_iso_lower_set : upper_set α ≃o lower_set α :=
{ to_fun := upper_set.compl,
inv_fun := lower_set.compl,
left_inv := upper_set.compl_compl,
right_inv := lower_set.compl_compl,
map_rel_iff' := λ _ _, upper_set.compl_le_compl }
end has_le
/-! #### Principal sets -/
namespace upper_set
section preorder
variables [preorder α] {a b : α}
/-- The smallest upper set containing a given element. -/
def Ici (a : α) : upper_set α := ⟨Ici a, is_upper_set_Ici a⟩
/-- The smallest upper set containing a given element. -/
def Ioi (a : α) : upper_set α := ⟨Ioi a, is_upper_set_Ioi a⟩
@[simp] lemma coe_Ici (a : α) : ↑(Ici a) = set.Ici a := rfl
@[simp] lemma coe_Ioi (a : α) : ↑(Ioi a) = set.Ioi a := rfl
@[simp] lemma mem_Ici_iff : b ∈ Ici a ↔ a ≤ b := iff.rfl
@[simp] lemma mem_Ioi_iff : b ∈ Ioi a ↔ a < b := iff.rfl
lemma Ici_le_Ioi (a : α) : Ici a ≤ Ioi a := Ioi_subset_Ici_self
@[simp] lemma Ioi_top [order_top α] : Ioi (⊤ : α) = ⊤ := set_like.coe_injective Ioi_top
@[simp] lemma Ici_bot [order_bot α] : Ici (⊥ : α) = ⊥ := set_like.coe_injective Ici_bot
end preorder
section semilattice_sup
variables [semilattice_sup α]
@[simp] lemma Ici_sup (a b : α) : Ici (a ⊔ b) = Ici a ⊔ Ici b := ext Ici_inter_Ici.symm
/-- `upper_set.Ici` as a `sup_hom`. -/
def Ici_sup_hom : sup_hom α (upper_set α) := ⟨Ici, Ici_sup⟩
@[simp] lemma Ici_sup_hom_apply (a : α) : Ici_sup_hom a = (Ici a) := rfl
end semilattice_sup
section complete_lattice
variables [complete_lattice α]
@[simp] lemma Ici_Sup (S : set α) : Ici (Sup S) = ⨆ a ∈ S, Ici a :=
set_like.ext $ λ c, by simp only [mem_Ici_iff, mem_supr_iff, Sup_le_iff]
@[simp] lemma Ici_supr (f : ι → α) : Ici (⨆ i, f i) = ⨆ i, Ici (f i) :=
set_like.ext $ λ c, by simp only [mem_Ici_iff, mem_supr_iff, supr_le_iff]
@[simp] lemma Ici_supr₂ (f : Π i, κ i → α) : Ici (⨆ i j, f i j) = ⨆ i j, Ici (f i j) :=
by simp_rw Ici_supr
/-- `upper_set.Ici` as a `Sup_hom`. -/
def Ici_Sup_hom : Sup_hom α (upper_set α) := ⟨Ici, λ s, (Ici_Sup s).trans Sup_image.symm⟩
@[simp] lemma Ici_Sup_hom_apply (a : α) : Ici_Sup_hom a = to_dual (Ici a) := rfl
end complete_lattice
end upper_set
namespace lower_set
section preorder
variables [preorder α] {a b : α}
/-- Principal lower set. `set.Iic` as a lower set. The smallest lower set containing a given
element. -/
def Iic (a : α) : lower_set α := ⟨Iic a, is_lower_set_Iic a⟩
/-- Strict principal lower set. `set.Iio` as a lower set. -/
def Iio (a : α) : lower_set α := ⟨Iio a, is_lower_set_Iio a⟩
@[simp] lemma coe_Iic (a : α) : ↑(Iic a) = set.Iic a := rfl
@[simp] lemma coe_Iio (a : α) : ↑(Iio a) = set.Iio a := rfl
@[simp] lemma mem_Iic_iff : b ∈ Iic a ↔ b ≤ a := iff.rfl
@[simp] lemma mem_Iio_iff : b ∈ Iio a ↔ b < a := iff.rfl
lemma Ioi_le_Ici (a : α) : Ioi a ≤ Ici a := Ioi_subset_Ici_self
@[simp] lemma Iic_top [order_top α] : Iic (⊤ : α) = ⊤ := set_like.coe_injective Iic_top
@[simp] lemma Iio_bot [order_bot α] : Iio (⊥ : α) = ⊥ := set_like.coe_injective Iio_bot
end preorder
section semilattice_inf
variables [semilattice_inf α]
@[simp] lemma Iic_inf (a b : α) : Iic (a ⊓ b) = Iic a ⊓ Iic b :=
set_like.coe_injective Iic_inter_Iic.symm
/-- `lower_set.Iic` as an `inf_hom`. -/
def Iic_inf_hom : inf_hom α (lower_set α) := ⟨Iic, Iic_inf⟩
@[simp] lemma coe_Iic_inf_hom : (Iic_inf_hom : α → lower_set α) = Iic := rfl
@[simp] lemma Iic_inf_hom_apply (a : α) : Iic_inf_hom a = Iic a := rfl
end semilattice_inf
section complete_lattice
variables [complete_lattice α]
@[simp] lemma Iic_Inf (S : set α) : Iic (Inf S) = ⨅ a ∈ S, Iic a :=
set_like.ext $ λ c, by simp only [mem_Iic_iff, mem_infi₂_iff, le_Inf_iff]
@[simp] lemma Iic_infi (f : ι → α) : Iic (⨅ i, f i) = ⨅ i, Iic (f i) :=
set_like.ext $ λ c, by simp only [mem_Iic_iff, mem_infi_iff, le_infi_iff]
@[simp] lemma Iic_infi₂ (f : Π i, κ i → α) : Iic (⨅ i j, f i j) = ⨅ i j, Iic (f i j) :=
by simp_rw Iic_infi
/-- `lower_set.Iic` as an `Inf_hom`. -/
def Iic_Inf_hom : Inf_hom α (lower_set α) := ⟨Iic, λ s, (Iic_Inf s).trans Inf_image.symm⟩
@[simp] lemma coe_Iic_Inf_hom : (Iic_Inf_hom : α → lower_set α) = Iic := rfl
@[simp] lemma Iic_Inf_hom_apply (a : α) : Iic_Inf_hom a = Iic a := rfl
end complete_lattice
end lower_set
section closure
variables [preorder α] {s t : set α} {x : α}
/-- The greatest upper set containing a given set. -/
def upper_closure (s : set α) : upper_set α :=
⟨{x | ∃ a ∈ s, a ≤ x}, λ x y h, Exists₂.imp $ λ a _, h.trans'⟩
/-- The least lower set containing a given set. -/
def lower_closure (s : set α) : lower_set α :=
⟨{x | ∃ a ∈ s, x ≤ a}, λ x y h, Exists₂.imp $ λ a _, h.trans⟩
@[simp, norm_cast] lemma coe_upper_closure (s : set α) :
↑(upper_closure s) = {x | ∃ a ∈ s, a ≤ x} := rfl
@[simp, norm_cast] lemma coe_lower_closure (s : set α) :
↑(lower_closure s) = {x | ∃ a ∈ s, x ≤ a} := rfl
@[simp] lemma mem_upper_closure : x ∈ upper_closure s ↔ ∃ a ∈ s, a ≤ x := iff.rfl
@[simp] lemma mem_lower_closure : x ∈ lower_closure s ↔ ∃ a ∈ s, x ≤ a := iff.rfl
lemma subset_upper_closure : s ⊆ upper_closure s := λ x hx, ⟨x, hx, le_rfl⟩
lemma subset_lower_closure : s ⊆ lower_closure s := λ x hx, ⟨x, hx, le_rfl⟩
lemma upper_closure_min (h : s ⊆ t) (ht : is_upper_set t) : ↑(upper_closure s) ⊆ t :=
λ a ⟨b, hb, hba⟩, ht hba $ h hb
lemma lower_closure_min (h : s ⊆ t) (ht : is_lower_set t) : ↑(lower_closure s) ⊆ t :=
λ a ⟨b, hb, hab⟩, ht hab $ h hb
@[simp] lemma upper_set.infi_Ici (s : set α) : (⨅ a ∈ s, upper_set.Ici a) = upper_closure s :=
by { ext, simp }
@[simp] lemma lower_set.supr_Iic (s : set α) : (⨆ a ∈ s, lower_set.Iic a) = lower_closure s :=
by { ext, simp }
lemma gc_upper_closure_coe :
galois_connection (to_dual ∘ upper_closure : set α → (upper_set α)ᵒᵈ) (coe ∘ of_dual) :=
λ s t, ⟨λ h, subset_upper_closure.trans $ upper_set.coe_subset_coe.2 h,
λ h, upper_closure_min h t.upper⟩
lemma gc_lower_closure_coe : galois_connection (lower_closure : set α → lower_set α) coe :=
λ s t, ⟨λ h, subset_lower_closure.trans $ lower_set.coe_subset_coe.2 h,
λ h, lower_closure_min h t.lower⟩
/-- `upper_closure` forms a reversed Galois insertion with the coercion from upper sets to sets. -/
def gi_upper_closure_coe :
galois_insertion (to_dual ∘ upper_closure : set α → (upper_set α)ᵒᵈ) (coe ∘ of_dual) :=
{ choice := λ s hs, to_dual (⟨s, λ a b hab ha, hs ⟨a, ha, hab⟩⟩ : upper_set α),
gc := gc_upper_closure_coe,
le_l_u := λ _, subset_upper_closure,
choice_eq := λ s hs,
of_dual.injective $ set_like.coe_injective $ subset_upper_closure.antisymm hs }
/-- `lower_closure` forms a Galois insertion with the coercion from lower sets to sets. -/
def gi_lower_closure_coe : galois_insertion (lower_closure : set α → lower_set α) coe :=
{ choice := λ s hs, ⟨s, λ a b hba ha, hs ⟨a, ha, hba⟩⟩,
gc := gc_lower_closure_coe,
le_l_u := λ _, subset_lower_closure,
choice_eq := λ s hs, set_like.coe_injective $ subset_lower_closure.antisymm hs }
lemma upper_closure_anti : antitone (upper_closure : set α → upper_set α) :=
gc_upper_closure_coe.monotone_l
lemma lower_closure_mono : monotone (lower_closure : set α → lower_set α) :=
gc_lower_closure_coe.monotone_l
@[simp] lemma upper_closure_empty : upper_closure (∅ : set α) = ⊤ := by { ext, simp }
@[simp] lemma lower_closure_empty : lower_closure (∅ : set α) = ⊥ := by { ext, simp }
@[simp] lemma upper_closure_univ : upper_closure (univ : set α) = ⊥ :=
le_bot_iff.1 subset_upper_closure
@[simp] lemma lower_closure_univ : lower_closure (univ : set α) = ⊤ :=
top_le_iff.1 subset_lower_closure
@[simp] lemma upper_closure_eq_top_iff : upper_closure s = ⊤ ↔ s = ∅ :=
⟨λ h, subset_empty_iff.1 $ subset_upper_closure.trans (congr_arg coe h).subset,
by { rintro rfl, exact upper_closure_empty }⟩
@[simp] lemma lower_closure_eq_bot_iff : lower_closure s = ⊥ ↔ s = ∅ :=
⟨λ h, subset_empty_iff.1 $ subset_lower_closure.trans (congr_arg coe h).subset,
by { rintro rfl, exact lower_closure_empty }⟩
@[simp] lemma upper_closure_union (s t : set α) :
upper_closure (s ∪ t) = upper_closure s ⊓ upper_closure t :=
by { ext, simp [or_and_distrib_right, exists_or_distrib] }
@[simp] lemma lower_closure_union (s t : set α) :
lower_closure (s ∪ t) = lower_closure s ⊔ lower_closure t :=
by { ext, simp [or_and_distrib_right, exists_or_distrib] }
@[simp] lemma upper_closure_Union (f : ι → set α) :
upper_closure (⋃ i, f i) = ⨅ i, upper_closure (f i) :=
by { ext, simp [←exists_and_distrib_right, @exists_comm α] }
@[simp] lemma lower_closure_Union (f : ι → set α) :
lower_closure (⋃ i, f i) = ⨆ i, lower_closure (f i) :=
by { ext, simp [←exists_and_distrib_right, @exists_comm α] }
@[simp] lemma upper_closure_sUnion (S : set (set α)) :
upper_closure (⋃₀ S) = ⨅ s ∈ S, upper_closure s :=
by simp_rw [sUnion_eq_bUnion, upper_closure_Union]
@[simp] lemma lower_closure_sUnion (S : set (set α)) :
lower_closure (⋃₀ S) = ⨆ s ∈ S, lower_closure s :=
by simp_rw [sUnion_eq_bUnion, lower_closure_Union]
lemma set.ord_connected.upper_closure_inter_lower_closure (h : s.ord_connected) :
↑(upper_closure s) ∩ ↑(lower_closure s) = s :=
(subset_inter subset_upper_closure subset_lower_closure).antisymm' $ λ a ⟨⟨b, hb, hba⟩, c, hc, hac⟩,
h.out hb hc ⟨hba, hac⟩
lemma ord_connected_iff_upper_closure_inter_lower_closure :
s.ord_connected ↔ ↑(upper_closure s) ∩ ↑(lower_closure s) = s :=
begin
refine ⟨set.ord_connected.upper_closure_inter_lower_closure, λ h, _⟩,
rw ←h,
exact (upper_set.upper _).ord_connected.inter (lower_set.lower _).ord_connected,
end
end closure
|
53521d98f1e26a091759ac61bc52026ebcdba245 | 7850aae797be6c31052ce4633d86f5991178d3df | /stage0/src/Lean/Elab/Tactic/Basic.lean | 29d88dc984432abd1dba19b262adbca48bf10afb | [
"Apache-2.0"
] | permissive | miriamgoetze/lean4 | 4dc24d4dbd360cc969713647c2958c6691947d16 | 062cc5d5672250be456a168e9c7b9299a9c69bdb | refs/heads/master | 1,685,865,971,011 | 1,624,107,703,000 | 1,624,107,703,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 23,546 | lean | /-
Copyright (c) 2020 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura, Sebastian Ullrich
-/
import Lean.Util.CollectMVars
import Lean.Parser.Command
import Lean.Meta.PPGoal
import Lean.Meta.Tactic.Assumption
import Lean.Meta.Tactic.Contradiction
import Lean.Meta.Tactic.Intro
import Lean.Meta.Tactic.Clear
import Lean.Meta.Tactic.Revert
import Lean.Meta.Tactic.Subst
import Lean.Elab.Util
import Lean.Elab.Term
import Lean.Elab.Binders
namespace Lean.Elab
open Meta
/- Assign `mvarId := sorry` -/
def admitGoal (mvarId : MVarId) : MetaM Unit :=
withMVarContext mvarId do
let mvarType ← inferType (mkMVar mvarId)
assignExprMVar mvarId (← mkSorry mvarType (synthetic := true))
def goalsToMessageData (goals : List MVarId) : MessageData :=
MessageData.joinSep (goals.map $ MessageData.ofGoal) m!"\n\n"
def Term.reportUnsolvedGoals (goals : List MVarId) : TermElabM Unit :=
withPPInaccessibleNames do
logError <| MessageData.tagged `Tactic.unsolvedGoals <| m!"unsolved goals\n{goalsToMessageData goals}"
goals.forM fun mvarId => admitGoal mvarId
namespace Tactic
structure Context where
main : MVarId
structure State where
goals : List MVarId
deriving Inhabited
structure SavedState where
term : Term.SavedState
tactic : State
abbrev TacticM := ReaderT Context $ StateRefT State TermElabM
abbrev Tactic := Syntax → TacticM Unit
-- Make the compiler generate specialized `pure`/`bind` so we do not have to optimize through the
-- whole monad stack at every use site. May eventually be covered by `deriving`.
instance : Monad TacticM := { inferInstanceAs (Monad TacticM) with }
def getGoals : TacticM (List MVarId) :=
return (← get).goals
def setGoals (mvarIds : List MVarId) : TacticM Unit :=
modify fun s => { s with goals := mvarIds }
def pruneSolvedGoals : TacticM Unit := do
let gs ← getGoals
let gs ← gs.filterM fun g => not <$> isExprMVarAssigned g
setGoals gs
def getUnsolvedGoals : TacticM (List MVarId) := do
pruneSolvedGoals
getGoals
@[inline] private def TacticM.runCore (x : TacticM α) (ctx : Context) (s : State) : TermElabM (α × State) :=
x ctx |>.run s
@[inline] private def TacticM.runCore' (x : TacticM α) (ctx : Context) (s : State) : TermElabM α :=
Prod.fst <$> x.runCore ctx s
def run (mvarId : MVarId) (x : TacticM Unit) : TermElabM (List MVarId) :=
withMVarContext mvarId do
let savedSyntheticMVars := (← get).syntheticMVars
modify fun s => { s with syntheticMVars := [] }
let aux : TacticM (List MVarId) :=
/- Important: the following `try` does not backtrack the state.
This is intentional because we don't want to backtrack the error messages when we catch the "abort internal exception"
We must define `run` here because we define `MonadExcept` instance for `TacticM` -/
try
x; getUnsolvedGoals
catch ex =>
if isAbortTacticException ex then
getUnsolvedGoals
else
throw ex
try
aux.runCore' { main := mvarId } { goals := [mvarId] }
finally
modify fun s => { s with syntheticMVars := savedSyntheticMVars }
protected def saveState : TacticM SavedState :=
return { term := (← Term.saveState), tactic := (← get) }
def SavedState.restore (b : SavedState) : TacticM Unit := do
b.term.restore
set b.tactic
protected def getCurrMacroScope : TacticM MacroScope := do pure (← readThe Term.Context).currMacroScope
protected def getMainModule : TacticM Name := do pure (← getEnv).mainModule
unsafe def mkTacticAttribute : IO (KeyedDeclsAttribute Tactic) :=
mkElabAttribute Tactic `Lean.Elab.Tactic.tacticElabAttribute `builtinTactic `tactic `Lean.Parser.Tactic `Lean.Elab.Tactic.Tactic "tactic"
@[builtinInit mkTacticAttribute] constant tacticElabAttribute : KeyedDeclsAttribute Tactic
/-
Important: we must define `evalTacticUsing` and `expandTacticMacroFns` before we define
the instance `MonadExcept` for `TacticM` since it backtracks the state including error messages,
and this is bad when rethrowing the exception at the `catch` block in these methods.
We marked these places with a `(*)` in these methods.
-/
private def evalTacticUsing (s : SavedState) (stx : Syntax) (tactics : List Tactic) : TacticM Unit := do
let rec loop : List Tactic → TacticM Unit
| [] => throwErrorAt stx "unexpected syntax {indentD stx}"
| evalFn::evalFns => do
try
evalFn stx
catch
| ex@(Exception.error _ _) =>
match evalFns with
| [] => throw ex -- (*)
| evalFns => s.restore; loop evalFns
| ex@(Exception.internal id _) =>
if id == unsupportedSyntaxExceptionId then
s.restore; loop evalFns
else
throw ex
loop tactics
def mkTacticInfo (mctxBefore : MetavarContext) (goalsBefore : List MVarId) (stx : Syntax) : TacticM Info :=
return Info.ofTacticInfo {
mctxBefore := mctxBefore
goalsBefore := goalsBefore
stx := stx
mctxAfter := (← getMCtx)
goalsAfter := (← getUnsolvedGoals)
}
def mkInitialTacticInfo (stx : Syntax) : TacticM (TacticM Info) := do
let mctxBefore ← getMCtx
let goalsBefore ← getUnsolvedGoals
return mkTacticInfo mctxBefore goalsBefore stx
@[inline] def withTacticInfoContext (stx : Syntax) (x : TacticM α) : TacticM α := do
withInfoContext x (← mkInitialTacticInfo stx)
mutual
partial def expandTacticMacroFns (stx : Syntax) (macros : List Macro) : TacticM Unit :=
let rec loop : List Macro → TacticM Unit
| [] => throwErrorAt stx "tactic '{stx.getKind}' has not been implemented"
| m::ms => do
let scp ← getCurrMacroScope
try
let stx' ← adaptMacro m stx
evalTactic stx'
catch ex =>
if ms.isEmpty then throw ex -- (*)
loop ms
loop macros
partial def expandTacticMacro (stx : Syntax) : TacticM Unit := do
expandTacticMacroFns stx (macroAttribute.getValues (← getEnv) stx.getKind)
partial def evalTacticAux (stx : Syntax) : TacticM Unit :=
withRef stx $ withIncRecDepth $ withFreshMacroScope $ match stx with
| Syntax.node k args =>
if k == nullKind then
-- Macro writers create a sequence of tactics `t₁ ... tₙ` using `mkNullNode #[t₁, ..., tₙ]`
stx.getArgs.forM evalTactic
else do
trace[Elab.step] "{stx}"
let s ← Tactic.saveState
match tacticElabAttribute.getValues (← getEnv) stx.getKind with
| [] => expandTacticMacro stx
| evalFns => evalTacticUsing s stx evalFns
| _ => throwError m!"unexpected tactic{indentD stx}"
partial def evalTactic (stx : Syntax) : TacticM Unit :=
withTacticInfoContext stx (evalTacticAux stx)
end
def throwNoGoalsToBeSolved : TacticM α :=
throwError "no goals to be solved"
def done : TacticM Unit := do
let gs ← getUnsolvedGoals
unless gs.isEmpty do
Term.reportUnsolvedGoals gs
throwAbortTactic
def focus (x : TacticM α) : TacticM α := do
let mvarId :: mvarIds ← getUnsolvedGoals | throwNoGoalsToBeSolved
setGoals [mvarId]
let a ← x
let mvarIds' ← getUnsolvedGoals
setGoals (mvarIds' ++ mvarIds)
pure a
def focusAndDone (tactic : TacticM α) : TacticM α :=
focus do
let a ← tactic
done
pure a
/- Close the main goal using the given tactic. If it fails, log the error and `admit` -/
def closeUsingOrAdmit (tac : TacticM Unit) : TacticM Unit := do
/- Important: we must define `closeUsingOrAdmit` before we define
the instance `MonadExcept` for `TacticM` since it backtracks the state including error messages. -/
let mvarId :: mvarIds ← getUnsolvedGoals | throwNoGoalsToBeSolved
try
focusAndDone tac
catch ex =>
logException ex
admitGoal mvarId
setGoals mvarIds
instance : MonadBacktrack SavedState TacticM where
saveState := Tactic.saveState
restoreState b := b.restore
@[inline] protected def tryCatch {α} (x : TacticM α) (h : Exception → TacticM α) : TacticM α := do
let b ← saveState
try x catch ex => b.restore; h ex
instance : MonadExcept Exception TacticM where
throw := throw
tryCatch := Tactic.tryCatch
@[inline] protected def orElse {α} (x y : TacticM α) : TacticM α := do
try x catch _ => y
instance {α} : OrElse (TacticM α) where
orElse := Tactic.orElse
/-
Save the current tactic state for a token `stx`.
This method is a no-op if `stx` has no position information.
We use this method to save the tactic state at punctuation such as `;`
-/
def saveTacticInfoForToken (stx : Syntax) : TacticM Unit := do
unless stx.getPos?.isNone do
withTacticInfoContext stx (pure ())
/- Elaborate `x` with `stx` on the macro stack -/
@[inline]
def withMacroExpansion {α} (beforeStx afterStx : Syntax) (x : TacticM α) : TacticM α :=
withMacroExpansionInfo beforeStx afterStx do
withTheReader Term.Context (fun ctx => { ctx with macroStack := { before := beforeStx, after := afterStx } :: ctx.macroStack }) x
/-- Adapt a syntax transformation to a regular tactic evaluator. -/
def adaptExpander (exp : Syntax → TacticM Syntax) : Tactic := fun stx => do
let stx' ← exp stx
withMacroExpansion stx stx' $ evalTactic stx'
def appendGoals (mvarIds : List MVarId) : TacticM Unit :=
modify fun s => { s with goals := s.goals ++ mvarIds }
def replaceMainGoal (mvarIds : List MVarId) : TacticM Unit := do
let (mvarId :: mvarIds') ← getGoals | throwNoGoalsToBeSolved
modify fun s => { s with goals := mvarIds ++ mvarIds' }
/-- Return the first goal. -/
def getMainGoal : TacticM MVarId := do
loop (← getGoals)
where
loop : List MVarId → TacticM MVarId
| [] => throwNoGoalsToBeSolved
| mvarId :: mvarIds => do
if (← isExprMVarAssigned mvarId) then
loop mvarIds
else
setGoals (mvarId :: mvarIds)
return mvarId
/-- Return the main goal metavariable declaration. -/
def getMainDecl : TacticM MetavarDecl := do
getMVarDecl (← getMainGoal)
/-- Return the main goal tag. -/
def getMainTag : TacticM Name :=
return (← getMainDecl).userName
/-- Return expected type for the main goal. -/
def getMainTarget : TacticM Expr := do
instantiateMVars (← getMainDecl).type
/-- Execute `x` using the main goal local context and instances -/
def withMainContext (x : TacticM α) : TacticM α := do
withMVarContext (← getMainGoal) x
/-- Evaluate `tac` at `mvarId`, and return the list of resulting subgoals. -/
def evalTacticAt (tac : Syntax) (mvarId : MVarId) : TacticM (List MVarId) := do
let gs ← getGoals
try
setGoals [mvarId]
evalTactic tac
pruneSolvedGoals
getGoals
finally
setGoals gs
def ensureHasNoMVars (e : Expr) : TacticM Unit := do
let e ← instantiateMVars e
let pendingMVars ← getMVars e
discard <| Term.logUnassignedUsingErrorInfos pendingMVars
if e.hasExprMVar then
throwError "tactic failed, resulting expression contains metavariables{indentExpr e}"
/-- Close main goal using the given expression. If `checkUnassigned == true`, then `val` must not contain unassinged metavariables. -/
def closeMainGoal (val : Expr) (checkUnassigned := true): TacticM Unit := do
if checkUnassigned then
ensureHasNoMVars val
assignExprMVar (← getMainGoal) val
replaceMainGoal []
@[inline] def liftMetaMAtMain (x : MVarId → MetaM α) : TacticM α := do
withMainContext do x (← getMainGoal)
@[inline] def liftMetaTacticAux (tac : MVarId → MetaM (α × List MVarId)) : TacticM α := do
withMainContext do
let (a, mvarIds) ← tac (← getMainGoal)
replaceMainGoal mvarIds
pure a
@[inline] def liftMetaTactic (tactic : MVarId → MetaM (List MVarId)) : TacticM Unit :=
liftMetaTacticAux fun mvarId => do
let gs ← tactic mvarId
pure ((), gs)
@[builtinTactic Lean.Parser.Tactic.«done»] def evalDone : Tactic := fun _ =>
done
def tryTactic? (tactic : TacticM α) : TacticM (Option α) := do
try
pure (some (← tactic))
catch _ =>
pure none
def tryTactic (tactic : TacticM α) : TacticM Bool := do
try
discard tactic
pure true
catch _ =>
pure false
/--
Use `parentTag` to tag untagged goals at `newGoals`.
If there are multiple new untagged goals, they are named using `<parentTag>.<newSuffix>_<idx>` where `idx > 0`.
If there is only one new untagged goal, then we just use `parentTag` -/
def tagUntaggedGoals (parentTag : Name) (newSuffix : Name) (newGoals : List MVarId) : TacticM Unit := do
let mctx ← getMCtx
let mut numAnonymous := 0
for g in newGoals do
if mctx.isAnonymousMVar g then
numAnonymous := numAnonymous + 1
modifyMCtx fun mctx => do
let mut mctx := mctx
let mut idx := 1
for g in newGoals do
if mctx.isAnonymousMVar g then
if numAnonymous == 1 then
mctx := mctx.renameMVar g parentTag
else
mctx := mctx.renameMVar g (parentTag ++ newSuffix.appendIndexAfter idx)
idx := idx + 1
pure mctx
@[builtinTactic seq1] def evalSeq1 : Tactic := fun stx => do
let args := stx[0].getArgs
for i in [:args.size] do
if i % 2 == 0 then
evalTactic args[i]
else
saveTacticInfoForToken args[i] -- add `TacticInfo` node for `;`
@[builtinTactic paren] def evalParen : Tactic := fun stx =>
evalTactic stx[1]
/- Evaluate `many (group (tactic >> optional ";")) -/
private def evalManyTacticOptSemi (stx : Syntax) : TacticM Unit := do
stx.forArgsM fun seqElem => do
evalTactic seqElem[0]
saveTacticInfoForToken seqElem[1] -- add TacticInfo node for `;`
@[builtinTactic tacticSeq1Indented] def evalTacticSeq1Indented : Tactic := fun stx =>
evalManyTacticOptSemi stx[0]
@[builtinTactic tacticSeqBracketed] def evalTacticSeqBracketed : Tactic := fun stx => do
let initInfo ← mkInitialTacticInfo stx[0]
withRef stx[2] <| closeUsingOrAdmit do
-- save state before/after entering focus on `{`
withInfoContext (pure ()) initInfo
evalManyTacticOptSemi stx[1]
@[builtinTactic Parser.Tactic.focus] def evalFocus : Tactic := fun stx => do
let mkInfo ← mkInitialTacticInfo stx[0]
focus do
-- show focused state on `focus`
withInfoContext (pure ()) mkInfo
evalTactic stx[1]
private def getOptRotation (stx : Syntax) : Nat :=
if stx.isNone then 1 else stx[0].toNat
@[builtinTactic Parser.Tactic.rotateLeft] def evalRotateLeft : Tactic := fun stx => do
let n := getOptRotation stx[1]
setGoals <| (← getGoals).rotateLeft n
@[builtinTactic Parser.Tactic.rotateRight] def evalRotateRight : Tactic := fun stx => do
let n := getOptRotation stx[1]
setGoals <| (← getGoals).rotateRight n
@[builtinTactic Parser.Tactic.open] def evalOpen : Tactic := fun stx => do
try
pushScope
let openDecls ← elabOpenDecl stx[1]
withTheReader Core.Context (fun ctx => { ctx with openDecls := openDecls }) do
evalTactic stx[3]
finally
popScope
@[builtinTactic Parser.Tactic.set_option] def elabSetOption : Tactic := fun stx => do
let options ← Elab.elabSetOption stx[1] stx[2]
withTheReader Core.Context (fun ctx => { ctx with maxRecDepth := maxRecDepth.get options, options := options }) do
evalTactic stx[4]
@[builtinTactic Parser.Tactic.allGoals] def evalAllGoals : Tactic := fun stx => do
let mvarIds ← getGoals
let mut mvarIdsNew := #[]
for mvarId in mvarIds do
unless (← isExprMVarAssigned mvarId) do
setGoals [mvarId]
try
evalTactic stx[1]
mvarIdsNew := mvarIdsNew ++ (← getUnsolvedGoals)
catch ex =>
logException ex
mvarIdsNew := mvarIdsNew.push mvarId
setGoals mvarIdsNew.toList
@[builtinTactic tacticSeq] def evalTacticSeq : Tactic := fun stx =>
evalTactic stx[0]
partial def evalChoiceAux (tactics : Array Syntax) (i : Nat) : TacticM Unit :=
if h : i < tactics.size then
let tactic := tactics.get ⟨i, h⟩
catchInternalId unsupportedSyntaxExceptionId
(evalTactic tactic)
(fun _ => evalChoiceAux tactics (i+1))
else
throwUnsupportedSyntax
@[builtinTactic choice] def evalChoice : Tactic := fun stx =>
evalChoiceAux stx.getArgs 0
@[builtinTactic skip] def evalSkip : Tactic := fun stx => pure ()
@[builtinTactic unknown] def evalUnknown : Tactic := fun stx => do
addCompletionInfo <| CompletionInfo.tactic stx (← getGoals)
@[builtinTactic failIfSuccess] def evalFailIfSuccess : Tactic := fun stx => do
let tactic := stx[1]
if (← try evalTactic tactic; pure true catch _ => pure false) then
throwError "tactic succeeded"
@[builtinTactic traceState] def evalTraceState : Tactic := fun stx => do
let gs ← getUnsolvedGoals
logInfo (goalsToMessageData gs)
@[builtinTactic Lean.Parser.Tactic.assumption] def evalAssumption : Tactic := fun stx =>
liftMetaTactic fun mvarId => do Meta.assumption mvarId; pure []
@[builtinTactic Lean.Parser.Tactic.contradiction] def evalContradiction : Tactic := fun stx =>
liftMetaTactic fun mvarId => do Meta.contradiction mvarId; pure []
@[builtinTactic Lean.Parser.Tactic.intro] def evalIntro : Tactic := fun stx => do
match stx with
| `(tactic| intro) => introStep `_
| `(tactic| intro $h:ident) => introStep h.getId
| `(tactic| intro _) => introStep `_
| `(tactic| intro $pat:term) => evalTactic (← `(tactic| intro h; match h with | $pat:term => ?_; try clear h))
| `(tactic| intro $h:term $hs:term*) => evalTactic (← `(tactic| intro $h:term; intro $hs:term*))
| _ => throwUnsupportedSyntax
where
introStep (n : Name) : TacticM Unit :=
liftMetaTactic fun mvarId => do
let (_, mvarId) ← Meta.intro mvarId n
pure [mvarId]
@[builtinTactic Lean.Parser.Tactic.introMatch] def evalIntroMatch : Tactic := fun stx => do
let matchAlts := stx[1]
let stxNew ← liftMacroM <| Term.expandMatchAltsIntoMatchTactic stx matchAlts
withMacroExpansion stx stxNew <| evalTactic stxNew
private def getIntrosSize : Expr → Nat
| Expr.forallE _ _ b _ => getIntrosSize b + 1
| Expr.letE _ _ _ b _ => getIntrosSize b + 1
| Expr.mdata _ b _ => getIntrosSize b
| _ => 0
/- Recall that `ident' := ident <|> Term.hole` -/
def getNameOfIdent' (id : Syntax) : Name :=
if id.isIdent then id.getId else `_
@[builtinTactic «intros»] def evalIntros : Tactic := fun stx =>
match stx with
| `(tactic| intros) => liftMetaTactic fun mvarId => do
let type ← Meta.getMVarType mvarId
let type ← instantiateMVars type
let n := getIntrosSize type
let (_, mvarId) ← Meta.introN mvarId n
pure [mvarId]
| `(tactic| intros $ids*) => liftMetaTactic fun mvarId => do
let (_, mvarId) ← Meta.introN mvarId ids.size (ids.map getNameOfIdent').toList
pure [mvarId]
| _ => throwUnsupportedSyntax
def getFVarId (id : Syntax) : TacticM FVarId := withRef id do
let fvar? ← Term.isLocalIdent? id;
match fvar? with
| some fvar => pure fvar.fvarId!
| none => throwError "unknown variable '{id.getId}'"
def getFVarIds (ids : Array Syntax) : TacticM (Array FVarId) := do
withMainContext do ids.mapM getFVarId
@[builtinTactic Lean.Parser.Tactic.revert] def evalRevert : Tactic := fun stx =>
match stx with
| `(tactic| revert $hs*) => do
let (_, mvarId) ← Meta.revert (← getMainGoal) (← getFVarIds hs)
replaceMainGoal [mvarId]
| _ => throwUnsupportedSyntax
/- Sort free variables using an order `x < y` iff `x` was defined after `y` -/
private def sortFVarIds (fvarIds : Array FVarId) : TacticM (Array FVarId) :=
withMainContext do
let lctx ← getLCtx
return fvarIds.qsort fun fvarId₁ fvarId₂ =>
match lctx.find? fvarId₁, lctx.find? fvarId₂ with
| some d₁, some d₂ => d₁.index > d₂.index
| some _, none => false
| none, some _ => true
| none, none => Name.quickLt fvarId₁ fvarId₂
@[builtinTactic Lean.Parser.Tactic.clear] def evalClear : Tactic := fun stx =>
match stx with
| `(tactic| clear $hs*) => do
let fvarIds ← getFVarIds hs
let fvarIds ← sortFVarIds fvarIds
for fvarId in fvarIds do
withMainContext do
let mvarId ← clear (← getMainGoal) fvarId
replaceMainGoal [mvarId]
| _ => throwUnsupportedSyntax
def forEachVar (hs : Array Syntax) (tac : MVarId → FVarId → MetaM MVarId) : TacticM Unit := do
for h in hs do
withMainContext do
let fvarId ← getFVarId h
let mvarId ← tac (← getMainGoal) (← getFVarId h)
replaceMainGoal [mvarId]
@[builtinTactic Lean.Parser.Tactic.subst] def evalSubst : Tactic := fun stx =>
match stx with
| `(tactic| subst $hs*) => forEachVar hs Meta.subst
| _ => throwUnsupportedSyntax
/--
First method searches for a metavariable `g` s.t. `tag` is a suffix of its name.
If none is found, then it searches for a metavariable `g` s.t. `tag` is a prefix of its name. -/
private def findTag? (mvarIds : List MVarId) (tag : Name) : TacticM (Option MVarId) := do
let mvarId? ← mvarIds.findM? fun mvarId => return tag.isSuffixOf (← getMVarDecl mvarId).userName
match mvarId? with
| some mvarId => return mvarId
| none => mvarIds.findM? fun mvarId => return tag.isPrefixOf (← getMVarDecl mvarId).userName
/--
Use position of `=> $body` for error messages.
If there is a line break before `body`, the message will be displayed on `=>` only,
but the "full range" for the info view will still include `body`. -/
def withCaseRef [Monad m] [MonadRef m] (arrow body : Syntax) (x : m α) : m α :=
withRef (mkNullNode #[arrow, body]) x
@[builtinTactic «case»] def evalCase : Tactic
| stx@`(tactic| case $tag $hs* =>%$arr $tac:tacticSeq) => do
let tag := tag.getId
let gs ← getUnsolvedGoals
let some g ← findTag? gs tag | throwError "tag not found"
let gs := gs.erase g
let mut g := g
unless hs.isEmpty do
let mvarDecl ← getMVarDecl g
let mut lctx := mvarDecl.lctx
let mut hs := hs
let n := lctx.numIndices
for i in [:n] do
let j := n - i - 1
match lctx.getAt? j with
| none => pure ()
| some localDecl =>
if localDecl.userName.hasMacroScopes then
let h := hs.back
if h.isIdent then
let newName := h.getId
lctx := lctx.setUserName localDecl.fvarId newName
hs := hs.pop
if hs.isEmpty then
break
unless hs.isEmpty do
logError m!"too many variable names provided at 'case'"
let mvarNew ← mkFreshExprMVarAt lctx mvarDecl.localInstances mvarDecl.type MetavarKind.syntheticOpaque mvarDecl.userName
assignExprMVar g mvarNew
g := mvarNew.mvarId!
setGoals [g]
let savedTag ← getMVarTag g
setMVarTag g Name.anonymous
try
withCaseRef arr tac do
closeUsingOrAdmit (withTacticInfoContext stx (evalTactic tac))
finally
setMVarTag g savedTag
done
setGoals gs
| _ => throwUnsupportedSyntax
@[builtinTactic «first»] partial def evalFirst : Tactic := fun stx => do
let tacs := stx[1].getArgs
if tacs.isEmpty then throwUnsupportedSyntax
loop tacs 0
where
loop (tacs : Array Syntax) (i : Nat) :=
if i == tacs.size - 1 then
evalTactic tacs[i][1]
else
evalTactic tacs[i][1] <|> loop tacs (i+1)
builtin_initialize registerTraceClass `Elab.tactic
end Lean.Elab.Tactic
|
b4e6c7f128445bd59345098d16d765c24fda2346 | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /tests/lean/promise.lean | 5ea3909121955f2dbc898d0cab7d36f964c71586 | [
"Apache-2.0",
"LLVM-exception",
"NCSA",
"LGPL-3.0-only",
"LicenseRef-scancode-inner-net-2.0",
"BSD-3-Clause",
"LGPL-2.0-or-later",
"Spencer-94",
"LGPL-2.1-or-later",
"HPND",
"LicenseRef-scancode-pcre",
"ISC",
"LGPL-2.1-only",
"LicenseRef-scancode-other-permissive",
"SunPro",
"CMU-Mach"... | permissive | leanprover/lean4 | 4bdf9790294964627eb9be79f5e8f6157780b4cc | f1f9dc0f2f531af3312398999d8b8303fa5f096b | refs/heads/master | 1,693,360,665,786 | 1,693,350,868,000 | 1,693,350,868,000 | 129,571,436 | 2,827 | 311 | Apache-2.0 | 1,694,716,156,000 | 1,523,760,560,000 | Lean | UTF-8 | Lean | false | false | 408 | lean | open IO
-- not in the run/ directory because then it would be run with -j0
#eval do
let promise ← Promise.new
promise.resolve 42
assert! promise.result.get = 42
#eval do
let ch ← Channel.new
let out ← IO.mkRef #[]
ch.send 0
let drainFinished ← ch.forAsync fun x => out.modify (·.push x)
ch.send 1
ch.close
ch.send 2
IO.wait drainFinished
assert! (← out.get) = #[0, 1]
|
cddffe5bea4d74162eccd9bba0281920931a7ada | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/geometry/manifold/diffeomorph.lean | 244e0eaa3675078d014d7574310a12d568de6eab | [
"Apache-2.0"
] | permissive | alreadydone/mathlib | dc0be621c6c8208c581f5170a8216c5ba6721927 | c982179ec21091d3e102d8a5d9f5fe06c8fafb73 | refs/heads/master | 1,685,523,275,196 | 1,670,184,141,000 | 1,670,184,141,000 | 287,574,545 | 0 | 0 | Apache-2.0 | 1,670,290,714,000 | 1,597,421,623,000 | Lean | UTF-8 | Lean | false | false | 21,066 | lean | /-
Copyright © 2020 Nicolò Cavalleri. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Nicolò Cavalleri, Yury Kudryashov
-/
import geometry.manifold.cont_mdiff_map
/-!
# Diffeomorphisms
This file implements diffeomorphisms.
## Definitions
* `diffeomorph I I' M M' n`: `n`-times continuously differentiable diffeomorphism between
`M` and `M'` with respect to I and I'; we do not introduce a separate definition for the case
`n = ∞`; we use notation instead.
* `diffeomorph.to_homeomorph`: reinterpret a diffeomorphism as a homeomorphism.
* `continuous_linear_equiv.to_diffeomorph`: reinterpret a continuous equivalence as
a diffeomorphism.
* `model_with_corners.trans_diffeomorph`: compose a given `model_with_corners` with a diffeomorphism
between the old and the new target spaces. Useful, e.g, to turn any finite dimensional manifold
into a manifold modelled on a Euclidean space.
* `diffeomorph.to_trans_diffeomorph`: the identity diffeomorphism between `M` with model `I` and `M`
with model `I.trans_diffeomorph e`.
## Notations
* `M ≃ₘ^n⟮I, I'⟯ M'` := `diffeomorph I J M N n`
* `M ≃ₘ⟮I, I'⟯ M'` := `diffeomorph I J M N ⊤`
* `E ≃ₘ^n[𝕜] E'` := `E ≃ₘ^n⟮𝓘(𝕜, E), 𝓘(𝕜, E')⟯ E'`
* `E ≃ₘ[𝕜] E'` := `E ≃ₘ⟮𝓘(𝕜, E), 𝓘(𝕜, E')⟯ E'`
## Implementation notes
This notion of diffeomorphism is needed although there is already a notion of structomorphism
because structomorphisms do not allow the model spaces `H` and `H'` of the two manifolds to be
different, i.e. for a structomorphism one has to impose `H = H'` which is often not the case in
practice.
## Keywords
diffeomorphism, manifold
-/
open_locale manifold topological_space
open function set
variables {𝕜 : Type*} [nontrivially_normed_field 𝕜]
{E : Type*} [normed_add_comm_group E] [normed_space 𝕜 E]
{E' : Type*} [normed_add_comm_group E'] [normed_space 𝕜 E']
{F : Type*} [normed_add_comm_group F] [normed_space 𝕜 F]
{H : Type*} [topological_space H]
{H' : Type*} [topological_space H']
{G : Type*} [topological_space G]
{G' : Type*} [topological_space G']
{I : model_with_corners 𝕜 E H} {I' : model_with_corners 𝕜 E' H'}
{J : model_with_corners 𝕜 F G} {J' : model_with_corners 𝕜 F G'}
variables {M : Type*} [topological_space M] [charted_space H M]
{M' : Type*} [topological_space M'] [charted_space H' M']
{N : Type*} [topological_space N] [charted_space G N]
{N' : Type*} [topological_space N'] [charted_space G' N']
{n : ℕ∞}
section defs
variables (I I' M M' n)
/--
`n`-times continuously differentiable diffeomorphism between `M` and `M'` with respect to I and I'
-/
@[protect_proj, nolint has_nonempty_instance]
structure diffeomorph extends M ≃ M' :=
(cont_mdiff_to_fun : cont_mdiff I I' n to_equiv)
(cont_mdiff_inv_fun : cont_mdiff I' I n to_equiv.symm)
end defs
localized "notation (name := diffeomorph) M ` ≃ₘ^` n:1000 `⟮`:50 I `, ` J `⟯ ` N :=
diffeomorph I J M N n" in manifold
localized "notation (name := diffeomorph.top) M ` ≃ₘ⟮` I `, ` J `⟯ ` N :=
diffeomorph I J M N ⊤" in manifold
localized "notation (name := diffeomorph.self) E ` ≃ₘ^` n:1000 `[`:50 𝕜 `] ` E' :=
diffeomorph (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') E E' n" in manifold
localized "notation (name := diffeomorph.self.top) E ` ≃ₘ[` 𝕜 `] ` E' :=
diffeomorph (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') E E' ⊤" in manifold
namespace diffeomorph
instance : has_coe_to_fun (M ≃ₘ^n⟮I, I'⟯ M') (λ _, M → M') := ⟨λe, e.to_equiv⟩
instance : has_coe (M ≃ₘ^n⟮I, I'⟯ M') C^n⟮I, M; I', M'⟯ := ⟨λ Φ, ⟨Φ, Φ.cont_mdiff_to_fun⟩⟩
@[continuity] protected lemma continuous (h : M ≃ₘ^n⟮I, I'⟯ M') : continuous h :=
h.cont_mdiff_to_fun.continuous
protected lemma cont_mdiff (h : M ≃ₘ^n⟮I, I'⟯ M') : cont_mdiff I I' n h :=
h.cont_mdiff_to_fun
protected lemma cont_mdiff_at (h : M ≃ₘ^n⟮I, I'⟯ M') {x} : cont_mdiff_at I I' n h x :=
h.cont_mdiff.cont_mdiff_at
protected lemma cont_mdiff_within_at (h : M ≃ₘ^n⟮I, I'⟯ M') {s x} :
cont_mdiff_within_at I I' n h s x :=
h.cont_mdiff_at.cont_mdiff_within_at
protected lemma cont_diff (h : E ≃ₘ^n[𝕜] E') : cont_diff 𝕜 n h :=
h.cont_mdiff.cont_diff
protected lemma smooth (h : M ≃ₘ⟮I, I'⟯ M') : smooth I I' h := h.cont_mdiff_to_fun
protected lemma mdifferentiable (h : M ≃ₘ^n⟮I, I'⟯ M') (hn : 1 ≤ n) : mdifferentiable I I' h :=
h.cont_mdiff.mdifferentiable hn
protected lemma mdifferentiable_on (h : M ≃ₘ^n⟮I, I'⟯ M') (s : set M) (hn : 1 ≤ n) :
mdifferentiable_on I I' h s :=
(h.mdifferentiable hn).mdifferentiable_on
@[simp] lemma coe_to_equiv (h : M ≃ₘ^n⟮I, I'⟯ M') : ⇑h.to_equiv = h := rfl
@[simp, norm_cast] lemma coe_coe (h : M ≃ₘ^n⟮I, I'⟯ M') : ⇑(h : C^n⟮I, M; I', M'⟯) = h := rfl
lemma to_equiv_injective : injective (diffeomorph.to_equiv : (M ≃ₘ^n⟮I, I'⟯ M') → (M ≃ M'))
| ⟨e, _, _⟩ ⟨e', _, _⟩ rfl := rfl
@[simp] lemma to_equiv_inj {h h' : M ≃ₘ^n⟮I, I'⟯ M'} : h.to_equiv = h'.to_equiv ↔ h = h' :=
to_equiv_injective.eq_iff
/-- Coercion to function `λ h : M ≃ₘ^n⟮I, I'⟯ M', (h : M → M')` is injective. -/
lemma coe_fn_injective : injective (λ (h : M ≃ₘ^n⟮I, I'⟯ M') (x : M), h x) :=
equiv.coe_fn_injective.comp to_equiv_injective
@[ext] lemma ext {h h' : M ≃ₘ^n⟮I, I'⟯ M'} (Heq : ∀ x, h x = h' x) : h = h' :=
coe_fn_injective $ funext Heq
section
variables (M I n)
/-- Identity map as a diffeomorphism. -/
protected def refl : M ≃ₘ^n⟮I, I⟯ M :=
{ cont_mdiff_to_fun := cont_mdiff_id,
cont_mdiff_inv_fun := cont_mdiff_id,
to_equiv := equiv.refl M }
@[simp] lemma refl_to_equiv : (diffeomorph.refl I M n).to_equiv = equiv.refl _ := rfl
@[simp] lemma coe_refl : ⇑(diffeomorph.refl I M n) = id := rfl
end
/-- Composition of two diffeomorphisms. -/
protected def trans (h₁ : M ≃ₘ^n⟮I, I'⟯ M') (h₂ : M' ≃ₘ^n⟮I', J⟯ N) :
M ≃ₘ^n⟮I, J⟯ N :=
{ cont_mdiff_to_fun := h₂.cont_mdiff_to_fun.comp h₁.cont_mdiff_to_fun,
cont_mdiff_inv_fun := h₁.cont_mdiff_inv_fun.comp h₂.cont_mdiff_inv_fun,
to_equiv := h₁.to_equiv.trans h₂.to_equiv }
@[simp] lemma trans_refl (h : M ≃ₘ^n⟮I, I'⟯ M') : h.trans (diffeomorph.refl I' M' n) = h :=
ext $ λ _, rfl
@[simp] lemma refl_trans (h : M ≃ₘ^n⟮I, I'⟯ M') : (diffeomorph.refl I M n).trans h = h :=
ext $ λ _, rfl
@[simp] lemma coe_trans (h₁ : M ≃ₘ^n⟮I, I'⟯ M') (h₂ : M' ≃ₘ^n⟮I', J⟯ N) :
⇑(h₁.trans h₂) = h₂ ∘ h₁ := rfl
/-- Inverse of a diffeomorphism. -/
protected def symm (h : M ≃ₘ^n⟮I, J⟯ N) : N ≃ₘ^n⟮J, I⟯ M :=
{ cont_mdiff_to_fun := h.cont_mdiff_inv_fun,
cont_mdiff_inv_fun := h.cont_mdiff_to_fun,
to_equiv := h.to_equiv.symm }
@[simp] lemma apply_symm_apply (h : M ≃ₘ^n⟮I, J⟯ N) (x : N) : h (h.symm x) = x :=
h.to_equiv.apply_symm_apply x
@[simp] lemma symm_apply_apply (h : M ≃ₘ^n⟮I, J⟯ N) (x : M) : h.symm (h x) = x :=
h.to_equiv.symm_apply_apply x
@[simp] lemma symm_refl : (diffeomorph.refl I M n).symm = diffeomorph.refl I M n :=
ext $ λ _, rfl
@[simp] lemma self_trans_symm (h : M ≃ₘ^n⟮I, J⟯ N) : h.trans h.symm = diffeomorph.refl I M n :=
ext h.symm_apply_apply
@[simp] lemma symm_trans_self (h : M ≃ₘ^n⟮I, J⟯ N) : h.symm.trans h = diffeomorph.refl J N n :=
ext h.apply_symm_apply
@[simp] lemma symm_trans' (h₁ : M ≃ₘ^n⟮I, I'⟯ M') (h₂ : M' ≃ₘ^n⟮I', J⟯ N) :
(h₁.trans h₂).symm = h₂.symm.trans h₁.symm := rfl
@[simp] lemma symm_to_equiv (h : M ≃ₘ^n⟮I, J⟯ N) : h.symm.to_equiv = h.to_equiv.symm := rfl
@[simp, mfld_simps] lemma to_equiv_coe_symm (h : M ≃ₘ^n⟮I, J⟯ N) : ⇑h.to_equiv.symm = h.symm := rfl
lemma image_eq_preimage (h : M ≃ₘ^n⟮I, J⟯ N) (s : set M) : h '' s = h.symm ⁻¹' s :=
h.to_equiv.image_eq_preimage s
lemma symm_image_eq_preimage (h : M ≃ₘ^n⟮I, J⟯ N) (s : set N) : h.symm '' s = h ⁻¹' s :=
h.symm.image_eq_preimage s
@[simp, mfld_simps] lemma range_comp {α} (h : M ≃ₘ^n⟮I, J⟯ N) (f : α → M) :
range (h ∘ f) = h.symm ⁻¹' (range f) :=
by rw [range_comp, image_eq_preimage]
@[simp] lemma image_symm_image (h : M ≃ₘ^n⟮I, J⟯ N) (s : set N) : h '' (h.symm '' s) = s :=
h.to_equiv.image_symm_image s
@[simp] lemma symm_image_image (h : M ≃ₘ^n⟮I, J⟯ N) (s : set M) : h.symm '' (h '' s) = s :=
h.to_equiv.symm_image_image s
/-- A diffeomorphism is a homeomorphism. -/
def to_homeomorph (h : M ≃ₘ^n⟮I, J⟯ N) : M ≃ₜ N :=
⟨h.to_equiv, h.continuous, h.symm.continuous⟩
@[simp] lemma to_homeomorph_to_equiv (h : M ≃ₘ^n⟮I, J⟯ N) :
h.to_homeomorph.to_equiv = h.to_equiv :=
rfl
@[simp] lemma symm_to_homeomorph (h : M ≃ₘ^n⟮I, J⟯ N) :
h.symm.to_homeomorph = h.to_homeomorph.symm :=
rfl
@[simp] lemma coe_to_homeomorph (h : M ≃ₘ^n⟮I, J⟯ N) : ⇑h.to_homeomorph = h := rfl
@[simp] lemma coe_to_homeomorph_symm (h : M ≃ₘ^n⟮I, J⟯ N) :
⇑h.to_homeomorph.symm = h.symm := rfl
@[simp] lemma cont_mdiff_within_at_comp_diffeomorph_iff {m} (h : M ≃ₘ^n⟮I, J⟯ N) {f : N → M'}
{s x} (hm : m ≤ n) :
cont_mdiff_within_at I I' m (f ∘ h) s x ↔
cont_mdiff_within_at J I' m f (h.symm ⁻¹' s) (h x) :=
begin
split,
{ intro Hfh,
rw [← h.symm_apply_apply x] at Hfh,
simpa only [(∘), h.apply_symm_apply]
using Hfh.comp (h x) (h.symm.cont_mdiff_within_at.of_le hm) (maps_to_preimage _ _) },
{ rw ← h.image_eq_preimage,
exact λ hf, hf.comp x (h.cont_mdiff_within_at.of_le hm) (maps_to_image _ _) }
end
@[simp] lemma cont_mdiff_on_comp_diffeomorph_iff {m} (h : M ≃ₘ^n⟮I, J⟯ N) {f : N → M'}
{s} (hm : m ≤ n) :
cont_mdiff_on I I' m (f ∘ h) s ↔ cont_mdiff_on J I' m f (h.symm ⁻¹' s) :=
h.to_equiv.forall_congr $ λ x, by simp only [hm, coe_to_equiv, symm_apply_apply,
cont_mdiff_within_at_comp_diffeomorph_iff, mem_preimage]
@[simp] lemma cont_mdiff_at_comp_diffeomorph_iff {m} (h : M ≃ₘ^n⟮I, J⟯ N) {f : N → M'} {x}
(hm : m ≤ n) :
cont_mdiff_at I I' m (f ∘ h) x ↔ cont_mdiff_at J I' m f (h x) :=
h.cont_mdiff_within_at_comp_diffeomorph_iff hm
@[simp] lemma cont_mdiff_comp_diffeomorph_iff {m} (h : M ≃ₘ^n⟮I, J⟯ N) {f : N → M'}
(hm : m ≤ n) :
cont_mdiff I I' m (f ∘ h) ↔ cont_mdiff J I' m f :=
h.to_equiv.forall_congr $ λ x, (h.cont_mdiff_at_comp_diffeomorph_iff hm)
@[simp] lemma cont_mdiff_within_at_diffeomorph_comp_iff {m} (h : M ≃ₘ^n⟮I, J⟯ N) {f : M' → M}
(hm : m ≤ n) {s x} :
cont_mdiff_within_at I' J m (h ∘ f) s x ↔ cont_mdiff_within_at I' I m f s x :=
⟨λ Hhf, by simpa only [(∘), h.symm_apply_apply]
using (h.symm.cont_mdiff_at.of_le hm).comp_cont_mdiff_within_at _ Hhf,
λ Hf, (h.cont_mdiff_at.of_le hm).comp_cont_mdiff_within_at _ Hf⟩
@[simp] lemma cont_mdiff_at_diffeomorph_comp_iff {m} (h : M ≃ₘ^n⟮I, J⟯ N) {f : M' → M}
(hm : m ≤ n) {x} :
cont_mdiff_at I' J m (h ∘ f) x ↔ cont_mdiff_at I' I m f x :=
h.cont_mdiff_within_at_diffeomorph_comp_iff hm
@[simp] lemma cont_mdiff_on_diffeomorph_comp_iff {m} (h : M ≃ₘ^n⟮I, J⟯ N) {f : M' → M}
(hm : m ≤ n) {s} :
cont_mdiff_on I' J m (h ∘ f) s ↔ cont_mdiff_on I' I m f s :=
forall₂_congr $ λ x hx, h.cont_mdiff_within_at_diffeomorph_comp_iff hm
@[simp] lemma cont_mdiff_diffeomorph_comp_iff {m} (h : M ≃ₘ^n⟮I, J⟯ N) {f : M' → M}
(hm : m ≤ n) :
cont_mdiff I' J m (h ∘ f) ↔ cont_mdiff I' I m f :=
forall_congr $ λ x, h.cont_mdiff_within_at_diffeomorph_comp_iff hm
lemma to_local_homeomorph_mdifferentiable (h : M ≃ₘ^n⟮I, J⟯ N) (hn : 1 ≤ n) :
h.to_homeomorph.to_local_homeomorph.mdifferentiable I J :=
⟨h.mdifferentiable_on _ hn, h.symm.mdifferentiable_on _ hn⟩
section constructions
/-- Product of two diffeomorphisms. -/
def prod_congr (h₁ : M ≃ₘ^n⟮I, I'⟯ M') (h₂ : N ≃ₘ^n⟮J, J'⟯ N') :
M × N ≃ₘ^n⟮I.prod J, I'.prod J'⟯ M' × N' :=
{ cont_mdiff_to_fun := (h₁.cont_mdiff.comp cont_mdiff_fst).prod_mk
(h₂.cont_mdiff.comp cont_mdiff_snd),
cont_mdiff_inv_fun := (h₁.symm.cont_mdiff.comp cont_mdiff_fst).prod_mk
(h₂.symm.cont_mdiff.comp cont_mdiff_snd),
to_equiv := h₁.to_equiv.prod_congr h₂.to_equiv }
@[simp] lemma prod_congr_symm (h₁ : M ≃ₘ^n⟮I, I'⟯ M') (h₂ : N ≃ₘ^n⟮J, J'⟯ N') :
(h₁.prod_congr h₂).symm = h₁.symm.prod_congr h₂.symm := rfl
@[simp] lemma coe_prod_congr (h₁ : M ≃ₘ^n⟮I, I'⟯ M') (h₂ : N ≃ₘ^n⟮J, J'⟯ N') :
⇑(h₁.prod_congr h₂) = prod.map h₁ h₂ := rfl
section
variables (I J J' M N N' n)
/-- `M × N` is diffeomorphic to `N × M`. -/
def prod_comm : M × N ≃ₘ^n⟮I.prod J, J.prod I⟯ N × M :=
{ cont_mdiff_to_fun := cont_mdiff_snd.prod_mk cont_mdiff_fst,
cont_mdiff_inv_fun := cont_mdiff_snd.prod_mk cont_mdiff_fst,
to_equiv := equiv.prod_comm M N }
@[simp] lemma prod_comm_symm : (prod_comm I J M N n).symm = prod_comm J I N M n := rfl
@[simp] lemma coe_prod_comm : ⇑(prod_comm I J M N n) = prod.swap := rfl
/-- `(M × N) × N'` is diffeomorphic to `M × (N × N')`. -/
def prod_assoc : (M × N) × N' ≃ₘ^n⟮(I.prod J).prod J', I.prod (J.prod J')⟯ M × (N × N') :=
{ cont_mdiff_to_fun := (cont_mdiff_fst.comp cont_mdiff_fst).prod_mk
((cont_mdiff_snd.comp cont_mdiff_fst).prod_mk cont_mdiff_snd),
cont_mdiff_inv_fun := (cont_mdiff_fst.prod_mk (cont_mdiff_fst.comp cont_mdiff_snd)).prod_mk
(cont_mdiff_snd.comp cont_mdiff_snd),
to_equiv := equiv.prod_assoc M N N' }
end
end constructions
variables [smooth_manifold_with_corners I M] [smooth_manifold_with_corners J N]
lemma unique_mdiff_on_image_aux (h : M ≃ₘ^n⟮I, J⟯ N) (hn : 1 ≤ n)
{s : set M} (hs : unique_mdiff_on I s) :
unique_mdiff_on J (h '' s) :=
begin
convert hs.unique_mdiff_on_preimage (h.to_local_homeomorph_mdifferentiable hn),
simp [h.image_eq_preimage]
end
@[simp] lemma unique_mdiff_on_image (h : M ≃ₘ^n⟮I, J⟯ N) (hn : 1 ≤ n) {s : set M} :
unique_mdiff_on J (h '' s) ↔ unique_mdiff_on I s :=
⟨λ hs, h.symm_image_image s ▸ h.symm.unique_mdiff_on_image_aux hn hs,
h.unique_mdiff_on_image_aux hn⟩
@[simp] lemma unique_mdiff_on_preimage (h : M ≃ₘ^n⟮I, J⟯ N) (hn : 1 ≤ n) {s : set N} :
unique_mdiff_on I (h ⁻¹' s) ↔ unique_mdiff_on J s :=
h.symm_image_eq_preimage s ▸ h.symm.unique_mdiff_on_image hn
@[simp] lemma unique_diff_on_image (h : E ≃ₘ^n[𝕜] F) (hn : 1 ≤ n) {s : set E} :
unique_diff_on 𝕜 (h '' s) ↔ unique_diff_on 𝕜 s :=
by simp only [← unique_mdiff_on_iff_unique_diff_on, unique_mdiff_on_image, hn]
@[simp] lemma unique_diff_on_preimage (h : E ≃ₘ^n[𝕜] F) (hn : 1 ≤ n) {s : set F} :
unique_diff_on 𝕜 (h ⁻¹' s) ↔ unique_diff_on 𝕜 s :=
h.symm_image_eq_preimage s ▸ h.symm.unique_diff_on_image hn
end diffeomorph
namespace continuous_linear_equiv
variable (e : E ≃L[𝕜] E')
/-- A continuous linear equivalence between normed spaces is a diffeomorphism. -/
def to_diffeomorph : E ≃ₘ[𝕜] E' :=
{ cont_mdiff_to_fun := e.cont_diff.cont_mdiff,
cont_mdiff_inv_fun := e.symm.cont_diff.cont_mdiff,
to_equiv := e.to_linear_equiv.to_equiv }
@[simp] lemma coe_to_diffeomorph : ⇑e.to_diffeomorph = e := rfl
@[simp] lemma symm_to_diffeomorph : e.symm.to_diffeomorph = e.to_diffeomorph.symm := rfl
@[simp] lemma coe_to_diffeomorph_symm : ⇑e.to_diffeomorph.symm = e.symm := rfl
end continuous_linear_equiv
namespace model_with_corners
variables (I) (e : E ≃ₘ[𝕜] E')
/-- Apply a diffeomorphism (e.g., a continuous linear equivalence) to the model vector space. -/
def trans_diffeomorph (I : model_with_corners 𝕜 E H) (e : E ≃ₘ[𝕜] E') :
model_with_corners 𝕜 E' H :=
{ to_local_equiv := I.to_local_equiv.trans e.to_equiv.to_local_equiv,
source_eq := by simp,
unique_diff' := by simp [range_comp e, I.unique_diff],
continuous_to_fun := e.continuous.comp I.continuous,
continuous_inv_fun := I.continuous_symm.comp e.symm.continuous }
@[simp, mfld_simps] lemma coe_trans_diffeomorph : ⇑(I.trans_diffeomorph e) = e ∘ I := rfl
@[simp, mfld_simps] lemma coe_trans_diffeomorph_symm :
⇑(I.trans_diffeomorph e).symm = I.symm ∘ e.symm := rfl
lemma trans_diffeomorph_range : range (I.trans_diffeomorph e) = e '' (range I) :=
range_comp e I
lemma coe_ext_chart_at_trans_diffeomorph (x : M) :
⇑(ext_chart_at (I.trans_diffeomorph e) x) = e ∘ ext_chart_at I x := rfl
lemma coe_ext_chart_at_trans_diffeomorph_symm (x : M) :
⇑(ext_chart_at (I.trans_diffeomorph e) x).symm = (ext_chart_at I x).symm ∘ e.symm := rfl
lemma ext_chart_at_trans_diffeomorph_target (x : M) :
(ext_chart_at (I.trans_diffeomorph e) x).target = e.symm ⁻¹' (ext_chart_at I x).target :=
by simp only [range_comp e, e.image_eq_preimage, preimage_preimage] with mfld_simps
end model_with_corners
namespace diffeomorph
variables (e : E ≃ₘ[𝕜] F)
instance smooth_manifold_with_corners_trans_diffeomorph [smooth_manifold_with_corners I M] :
smooth_manifold_with_corners (I.trans_diffeomorph e) M :=
begin
refine smooth_manifold_with_corners_of_cont_diff_on _ _ (λ e₁ e₂ h₁ h₂, _),
refine e.cont_diff.comp_cont_diff_on
(((cont_diff_groupoid ⊤ I).compatible h₁ h₂).1.comp
e.symm.cont_diff.cont_diff_on _),
mfld_set_tac
end
variables (I M)
/-- The identity diffeomorphism between a manifold with model `I` and the same manifold
with model `I.trans_diffeomorph e`. -/
def to_trans_diffeomorph (e : E ≃ₘ[𝕜] F) : M ≃ₘ⟮I, I.trans_diffeomorph e⟯ M :=
{ to_equiv := equiv.refl M,
cont_mdiff_to_fun := λ x,
begin
refine cont_mdiff_within_at_iff'.2 ⟨continuous_within_at_id, _⟩,
refine e.cont_diff.cont_diff_within_at.congr' (λ y hy, _) _,
{ simp only [equiv.coe_refl, id, (∘), I.coe_ext_chart_at_trans_diffeomorph,
(ext_chart_at I x).right_inv hy.1] },
exact ⟨(ext_chart_at I x).map_source (mem_ext_chart_source I x), trivial,
by simp only with mfld_simps⟩
end,
cont_mdiff_inv_fun := λ x,
begin
refine cont_mdiff_within_at_iff'.2 ⟨continuous_within_at_id, _⟩,
refine e.symm.cont_diff.cont_diff_within_at.congr' (λ y hy, _) _,
{ simp only [mem_inter_iff, I.ext_chart_at_trans_diffeomorph_target] at hy,
simp only [equiv.coe_refl, equiv.refl_symm, id, (∘),
I.coe_ext_chart_at_trans_diffeomorph_symm, (ext_chart_at I x).right_inv hy.1] },
exact ⟨(ext_chart_at _ x).map_source (mem_ext_chart_source _ x), trivial,
by simp only [e.symm_apply_apply, equiv.refl_symm, equiv.coe_refl] with mfld_simps⟩
end }
variables {I M}
@[simp] lemma cont_mdiff_within_at_trans_diffeomorph_right {f : M' → M} {x s} :
cont_mdiff_within_at I' (I.trans_diffeomorph e) n f s x ↔
cont_mdiff_within_at I' I n f s x :=
(to_trans_diffeomorph I M e).cont_mdiff_within_at_diffeomorph_comp_iff le_top
@[simp] lemma cont_mdiff_at_trans_diffeomorph_right {f : M' → M} {x} :
cont_mdiff_at I' (I.trans_diffeomorph e) n f x ↔ cont_mdiff_at I' I n f x :=
(to_trans_diffeomorph I M e).cont_mdiff_at_diffeomorph_comp_iff le_top
@[simp] lemma cont_mdiff_on_trans_diffeomorph_right {f : M' → M} {s} :
cont_mdiff_on I' (I.trans_diffeomorph e) n f s ↔ cont_mdiff_on I' I n f s :=
(to_trans_diffeomorph I M e).cont_mdiff_on_diffeomorph_comp_iff le_top
@[simp] lemma cont_mdiff_trans_diffeomorph_right {f : M' → M} :
cont_mdiff I' (I.trans_diffeomorph e) n f ↔ cont_mdiff I' I n f :=
(to_trans_diffeomorph I M e).cont_mdiff_diffeomorph_comp_iff le_top
@[simp] lemma smooth_trans_diffeomorph_right {f : M' → M} :
smooth I' (I.trans_diffeomorph e) f ↔ smooth I' I f :=
cont_mdiff_trans_diffeomorph_right e
@[simp] lemma cont_mdiff_within_at_trans_diffeomorph_left {f : M → M'} {x s} :
cont_mdiff_within_at (I.trans_diffeomorph e) I' n f s x ↔
cont_mdiff_within_at I I' n f s x :=
((to_trans_diffeomorph I M e).cont_mdiff_within_at_comp_diffeomorph_iff le_top).symm
@[simp] lemma cont_mdiff_at_trans_diffeomorph_left {f : M → M'} {x} :
cont_mdiff_at (I.trans_diffeomorph e) I' n f x ↔ cont_mdiff_at I I' n f x :=
((to_trans_diffeomorph I M e).cont_mdiff_at_comp_diffeomorph_iff le_top).symm
@[simp] lemma cont_mdiff_on_trans_diffeomorph_left {f : M → M'} {s} :
cont_mdiff_on (I.trans_diffeomorph e) I' n f s ↔ cont_mdiff_on I I' n f s :=
((to_trans_diffeomorph I M e).cont_mdiff_on_comp_diffeomorph_iff le_top).symm
@[simp] lemma cont_mdiff_trans_diffeomorph_left {f : M → M'} :
cont_mdiff (I.trans_diffeomorph e) I' n f ↔ cont_mdiff I I' n f :=
((to_trans_diffeomorph I M e).cont_mdiff_comp_diffeomorph_iff le_top).symm
@[simp] lemma smooth_trans_diffeomorph_left {f : M → M'} :
smooth (I.trans_diffeomorph e) I' f ↔ smooth I I' f :=
e.cont_mdiff_trans_diffeomorph_left
end diffeomorph
|
9a8a3f17507f2d8b149085ad23e894d281c849f2 | 7cef822f3b952965621309e88eadf618da0c8ae9 | /src/ring_theory/subring.lean | 383c11bc3e5f40a2d61ac2f6017b18d90030ebd6 | [
"Apache-2.0"
] | permissive | rmitta/mathlib | 8d90aee30b4db2b013e01f62c33f297d7e64a43d | 883d974b608845bad30ae19e27e33c285200bf84 | refs/heads/master | 1,585,776,832,544 | 1,576,874,096,000 | 1,576,874,096,000 | 153,663,165 | 0 | 2 | Apache-2.0 | 1,544,806,490,000 | 1,539,884,365,000 | Lean | UTF-8 | Lean | false | false | 8,039 | lean | /-
Copyright (c) 2018 Johan Commelin. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johan Commelin
-/
import group_theory.subgroup
import algebra.ring
universes u v
open group
variables {R : Type u} [ring R]
section prio
set_option default_priority 100 -- see Note [default priority]
/-- `S` is a subring: a set containing 1 and closed under multiplication, addition and and additive inverse. -/
class is_subring (S : set R) extends is_add_subgroup S, is_submonoid S : Prop.
end prio
instance subset.ring {S : set R} [is_subring S] : ring S :=
by subtype_instance
instance subtype.ring {S : set R} [is_subring S] : ring (subtype S) := subset.ring
namespace is_ring_hom
instance {S : set R} [is_subring S] : is_ring_hom (@subtype.val R S) :=
by refine {..} ; intros ; refl
instance is_subring_preimage {R : Type u} {S : Type v} [ring R] [ring S]
(f : R → S) [is_ring_hom f] (s : set S) [is_subring s] : is_subring (f ⁻¹' s) := {}
instance is_subring_image {R : Type u} {S : Type v} [ring R] [ring S]
(f : R → S) [is_ring_hom f] (s : set R) [is_subring s] : is_subring (f '' s) := {}
instance is_subring_set_range {R : Type u} {S : Type v} [ring R] [ring S]
(f : R → S) [is_ring_hom f] : is_subring (set.range f) := {}
end is_ring_hom
instance subtype_val.is_ring_hom {s : set R} [is_subring s] :
is_ring_hom (subtype.val : s → R) :=
{ ..subtype_val.is_add_group_hom, ..subtype_val.is_monoid_hom }
instance coe.is_ring_hom {s : set R} [is_subring s] : is_ring_hom (coe : s → R) :=
subtype_val.is_ring_hom
instance subtype_mk.is_ring_hom {γ : Type*} [ring γ] {s : set R} [is_subring s] (f : γ → R)
[is_ring_hom f] (h : ∀ x, f x ∈ s) : is_ring_hom (λ x, (⟨f x, h x⟩ : s)) :=
{ ..subtype_mk.is_add_group_hom f h, ..subtype_mk.is_monoid_hom f h }
instance set_inclusion.is_ring_hom {s t : set R} [is_subring s] [is_subring t] (h : s ⊆ t) :
is_ring_hom (set.inclusion h) :=
subtype_mk.is_ring_hom _ _
variables {cR : Type u} [comm_ring cR]
instance subset.comm_ring {S : set cR} [is_subring S] : comm_ring S :=
by subtype_instance
instance subtype.comm_ring {S : set cR} [is_subring S] : comm_ring (subtype S) := subset.comm_ring
instance subring.domain {D : Type*} [integral_domain D] (S : set D) [is_subring S] : integral_domain S :=
by subtype_instance
instance is_subring.inter (S₁ S₂ : set R) [is_subring S₁] [is_subring S₂] :
is_subring (S₁ ∩ S₂) :=
{ }
instance is_subring.Inter {ι : Sort*} (S : ι → set R) [h : ∀ y : ι, is_subring (S y)] :
is_subring (set.Inter S) :=
{ }
lemma is_subring_Union_of_directed {ι : Type*} [hι : nonempty ι]
(s : ι → set R) [∀ i, is_subring (s i)]
(directed : ∀ i j, ∃ k, s i ⊆ s k ∧ s j ⊆ s k) :
is_subring (⋃i, s i) :=
{ to_is_add_subgroup := is_add_subgroup_Union_of_directed s directed,
to_is_submonoid := is_submonoid_Union_of_directed s directed }
namespace ring
def closure (s : set R) := add_group.closure (monoid.closure s)
variable {s : set R}
local attribute [reducible] closure
theorem exists_list_of_mem_closure {a : R} (h : a ∈ closure s) :
(∃ L : list (list R), (∀ l ∈ L, ∀ x ∈ l, x ∈ s ∨ x = (-1:R)) ∧ (L.map list.prod).sum = a) :=
add_group.in_closure.rec_on h
(λ x hx, match x, monoid.exists_list_of_mem_closure hx with
| _, ⟨L, h1, rfl⟩ := ⟨[L], list.forall_mem_singleton.2 (λ r hr, or.inl (h1 r hr)), zero_add _⟩
end)
⟨[], list.forall_mem_nil _, rfl⟩
(λ b _ ih, match b, ih with
| _, ⟨L1, h1, rfl⟩ := ⟨L1.map (list.cons (-1)),
λ L2 h2, match L2, list.mem_map.1 h2 with
| _, ⟨L3, h3, rfl⟩ := list.forall_mem_cons.2 ⟨or.inr rfl, h1 L3 h3⟩
end,
by simp only [list.map_map, (∘), list.prod_cons, neg_one_mul];
exact list.rec_on L1 neg_zero.symm (λ hd tl ih,
by rw [list.map_cons, list.sum_cons, ih, list.map_cons, list.sum_cons, neg_add])⟩
end)
(λ r1 r2 hr1 hr2 ih1 ih2, match r1, r2, ih1, ih2 with
| _, _, ⟨L1, h1, rfl⟩, ⟨L2, h2, rfl⟩ := ⟨L1 ++ L2, list.forall_mem_append.2 ⟨h1, h2⟩,
by rw [list.map_append, list.sum_append]⟩
end)
@[elab_as_eliminator]
protected theorem in_closure.rec_on {C : R → Prop} {x : R} (hx : x ∈ closure s)
(h1 : C 1) (hneg1 : C (-1)) (hs : ∀ z ∈ s, ∀ n, C n → C (z * n))
(ha : ∀ {x y}, C x → C y → C (x + y)) : C x :=
begin
have h0 : C 0 := add_neg_self (1:R) ▸ ha h1 hneg1,
rcases exists_list_of_mem_closure hx with ⟨L, HL, rfl⟩, clear hx,
induction L with hd tl ih, { exact h0 },
rw list.forall_mem_cons at HL,
suffices : C (list.prod hd),
{ rw [list.map_cons, list.sum_cons],
exact ha this (ih HL.2) },
replace HL := HL.1, clear ih tl,
suffices : ∃ L : list R, (∀ x ∈ L, x ∈ s) ∧ (list.prod hd = list.prod L ∨ list.prod hd = -list.prod L),
{ rcases this with ⟨L, HL', HP | HP⟩,
{ rw HP, clear HP HL hd, induction L with hd tl ih, { exact h1 },
rw list.forall_mem_cons at HL',
rw list.prod_cons,
exact hs _ HL'.1 _ (ih HL'.2) },
rw HP, clear HP HL hd, induction L with hd tl ih, { exact hneg1 },
rw [list.prod_cons, neg_mul_eq_mul_neg],
rw list.forall_mem_cons at HL',
exact hs _ HL'.1 _ (ih HL'.2) },
induction hd with hd tl ih,
{ exact ⟨[], list.forall_mem_nil _, or.inl rfl⟩ },
rw list.forall_mem_cons at HL,
rcases ih HL.2 with ⟨L, HL', HP | HP⟩; cases HL.1 with hhd hhd,
{ exact ⟨hd :: L, list.forall_mem_cons.2 ⟨hhd, HL'⟩, or.inl $
by rw [list.prod_cons, list.prod_cons, HP]⟩ },
{ exact ⟨L, HL', or.inr $ by rw [list.prod_cons, hhd, neg_one_mul, HP]⟩ },
{ exact ⟨hd :: L, list.forall_mem_cons.2 ⟨hhd, HL'⟩, or.inr $
by rw [list.prod_cons, list.prod_cons, HP, neg_mul_eq_mul_neg]⟩ },
{ exact ⟨L, HL', or.inl $ by rw [list.prod_cons, hhd, HP, neg_one_mul, neg_neg]⟩ }
end
instance : is_subring (closure s) :=
{ one_mem := add_group.mem_closure (is_submonoid.one_mem _),
mul_mem := λ a b ha hb, add_group.in_closure.rec_on hb
(λ b hb, add_group.in_closure.rec_on ha
(λ a ha, add_group.subset_closure (is_submonoid.mul_mem ha hb))
((zero_mul b).symm ▸ is_add_submonoid.zero_mem _)
(λ a ha hab, (neg_mul_eq_neg_mul a b) ▸ is_add_subgroup.neg_mem hab)
(λ a c ha hc hab hcb, (add_mul a c b).symm ▸ is_add_submonoid.add_mem hab hcb))
((mul_zero a).symm ▸ is_add_submonoid.zero_mem _)
(λ b hb hab, (neg_mul_eq_mul_neg a b) ▸ is_add_subgroup.neg_mem hab)
(λ b c hb hc hab hac, (mul_add a b c).symm ▸ is_add_submonoid.add_mem hab hac),
.. add_group.closure.is_add_subgroup _ }
theorem mem_closure {a : R} : a ∈ s → a ∈ closure s :=
add_group.mem_closure ∘ @monoid.subset_closure _ _ _ _
theorem subset_closure : s ⊆ closure s :=
λ _, mem_closure
theorem closure_subset {t : set R} [is_subring t] : s ⊆ t → closure s ⊆ t :=
add_group.closure_subset ∘ monoid.closure_subset
theorem closure_subset_iff (s t : set R) [is_subring t] : closure s ⊆ t ↔ s ⊆ t :=
(add_group.closure_subset_iff _ t).trans
⟨set.subset.trans monoid.subset_closure, monoid.closure_subset⟩
theorem closure_mono {s t : set R} (H : s ⊆ t) : closure s ⊆ closure t :=
closure_subset $ set.subset.trans H subset_closure
lemma image_closure {S : Type*} [ring S] (f : R → S) [is_ring_hom f] (s : set R) :
f '' closure s = closure (f '' s) :=
le_antisymm
begin
rintros _ ⟨x, hx, rfl⟩,
apply in_closure.rec_on hx; intros,
{ rw [is_monoid_hom.map_one f], apply is_submonoid.one_mem },
{ rw [is_ring_hom.map_neg f, is_monoid_hom.map_one f],
apply is_add_subgroup.neg_mem, apply is_submonoid.one_mem },
{ rw [is_monoid_hom.map_mul f],
apply is_submonoid.mul_mem; solve_by_elim [subset_closure, set.mem_image_of_mem] },
{ rw [is_ring_hom.map_add f], apply is_add_submonoid.add_mem, assumption' },
end
(closure_subset $ set.image_subset _ subset_closure)
end ring
|
19e5b2403b9713ebf6bab92f034e3a9edf5c9255 | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /src/Lean/Widget/Diff.lean | 55c682366083676df7f7de8e645312391c2432fa | [
"Apache-2.0",
"LLVM-exception",
"NCSA",
"LGPL-3.0-only",
"LicenseRef-scancode-inner-net-2.0",
"BSD-3-Clause",
"LGPL-2.0-or-later",
"Spencer-94",
"LGPL-2.1-or-later",
"HPND",
"LicenseRef-scancode-pcre",
"ISC",
"LGPL-2.1-only",
"LicenseRef-scancode-other-permissive",
"SunPro",
"CMU-Mach"... | permissive | leanprover/lean4 | 4bdf9790294964627eb9be79f5e8f6157780b4cc | f1f9dc0f2f531af3312398999d8b8303fa5f096b | refs/heads/master | 1,693,360,665,786 | 1,693,350,868,000 | 1,693,350,868,000 | 129,571,436 | 2,827 | 311 | Apache-2.0 | 1,694,716,156,000 | 1,523,760,560,000 | Lean | UTF-8 | Lean | false | false | 13,213 | lean | /-
Copyright (c) 2022 E.W.Ayers. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: E.W.Ayers
-/
import Lean.Meta.PPGoal
import Lean.Widget.InteractiveCode
import Lean.Widget.InteractiveGoal
import Lean.Data.Lsp.Extra
import Lean.Elab.InfoTree
namespace Lean.Widget
register_builtin_option showTacticDiff : Bool := {
defValue := true
descr := "When true, interactive goals for tactics will be decorated with diffing information. "
}
open Server Std Lean SubExpr
/-- A marker for a point in the expression where a subexpression has been inserted.
NOTE: in the future we may add other tags.
-/
private inductive ExprDiffTag where
| change
| delete
| insert
def ExprDiffTag.toDiffTag : (useAfter : Bool) → ExprDiffTag → Lean.Widget.DiffTag
| true, .change => .wasChanged
| false, .change => .willChange
| true, .delete => .wasDeleted
| false, .delete => .willDelete
| true, .insert => .wasInserted
| false, .insert => .willInsert
def ExprDiffTag.toString : ExprDiffTag → String
| .change => "change"
| .delete => "delete"
| .insert => "insert"
instance : ToString ExprDiffTag := ⟨ExprDiffTag.toString⟩
/-- A description of the differences between a pair of expressions `before`, `after : Expr`.
The information can be used to display a 'visual diff' for
either `before`, showing the parts of the expression that are about to change,
or `after` showing which parts of the expression have changed. -/
structure ExprDiff where
/-- Map from subexpr positions in `e₀` to diff points.-/
changesBefore : PosMap ExprDiffTag := ∅
/-- A map from subexpr positions in `e₁` to 'diff points' which are tags
describing how the expression has changed relative to `before` at the given position.-/
changesAfter : PosMap ExprDiffTag := ∅
instance : EmptyCollection ExprDiff := ⟨{}⟩
instance : Append ExprDiff where
append a b := {
changesBefore := RBMap.mergeBy (fun _ _ b => b) a.changesBefore b.changesBefore,
changesAfter := RBMap.mergeBy (fun _ _ b => b) a.changesAfter b.changesAfter
}
instance : ToString ExprDiff where
toString x :=
let f := fun (p : PosMap ExprDiffTag) =>
RBMap.toList p |>.map (fun (k,v) => s!"({toString k}:{toString v})")
s!"before: {f x.changesBefore}\nafter: {f x.changesAfter}"
/-- Add a tag at the given position to the `changesBefore` dict. -/
def ExprDiff.insertBeforeChange (p : Pos) (d : ExprDiffTag := .change) (δ : ExprDiff) : ExprDiff :=
{δ with changesBefore := δ.changesBefore.insert p d}
/-- Add a tag at the given position to the `changesAfter` dict. -/
def ExprDiff.insertAfterChange (p : Pos) (d : ExprDiffTag := .change) (δ : ExprDiff) : ExprDiff :=
{δ with changesAfter := δ.changesAfter.insert p d}
def ExprDiff.withChangePos (before after : Pos) (d : ExprDiffTag := .change) : ExprDiff :=
{ changesAfter := RBMap.empty.insert after d
changesBefore := RBMap.empty.insert before d
}
/-- Add a tag to the diff at the positions given by `before` and `after`. -/
def ExprDiff.withChange (before after : SubExpr) (d : ExprDiffTag := .change) : ExprDiff :=
ExprDiff.withChangePos before.pos after.pos d
/-- If true, the expression before and the expression after are identical. -/
def ExprDiff.isEmpty (d : ExprDiff) : Bool :=
d.changesAfter.isEmpty ∧ d.changesBefore.isEmpty
/-- Computes a diff between `before` and `after` expressions.
This works by recursively comparing function arguments.
TODO(ed): experiment with a 'greatest common subexpression' design where
given `e₀`, `e₁`, find the greatest common subexpressions `Xs : Array Expr` and a congruence `F` such that
`e₀ = F[A₀[..Xs]]` and `e₀ = F[A₁[..Xs]]`. Then, we can have fancy diff highlighting where common subexpressions are not highlighted.
## Diffing binders
Two binding domains are identified if they have the same user name and the same type.
The most common tactic that modifies binders is after an `intros`.
To deal with this case, if `before = (a : α) → β` and `after`, is not a matching binder (ie: not `(a : α) → _`)
then we instantiate the `before` variable in a new context and continue diffing `β` against `after`.
-/
partial def exprDiffCore (before after : SubExpr) : MetaM ExprDiff := do
if before.expr == after.expr then
return ∅
match before.expr, after.expr with
| .mdata _ e₀, _ => exprDiffCore {before with expr := e₀} after
| _, .mdata _ e₁ => exprDiffCore before {after with expr := e₁}
| .app .., .app .. =>
let (fn₀, args₀) := after.expr.withApp Prod.mk
let (fn₁, args₁) := before.expr.withApp Prod.mk
if fn₀ != fn₁ || args₀.size != args₁.size then
return ExprDiff.withChange before after
let args := Array.zip args₀ args₁
let args ← args.mapIdxM (fun i (beforeArg, afterArg) =>
exprDiffCore
⟨beforeArg, before.pos.pushNaryArg args₀.size i⟩
⟨afterArg, after.pos.pushNaryArg args₀.size i⟩
)
return args.foldl (init := ∅) (· ++ ·)
| .forallE .., _ => piDiff before after
| .lam n₀ d₀ b₀ i₀, .lam n₁ d₁ b₁ i₁=>
if n₀ != n₁ || i₀ != i₁ then
return ExprDiff.withChange before after
let δd ← exprDiffCore ⟨d₀, before.pos.pushBindingDomain⟩ ⟨d₁, after.pos.pushBindingDomain⟩
if δd.isEmpty then
return ← exprDiffCore ⟨b₀, before.pos.pushBindingBody⟩ ⟨b₁, after.pos.pushBindingBody⟩
else
return δd ++ ExprDiff.withChangePos before.pos.pushBindingBody after.pos.pushBindingBody
| .proj n₀ i₀ e₀, .proj n₁ i₁ e₁ =>
if n₀ != n₁ || i₀ != i₁ then
return ExprDiff.withChange before after
else
exprDiffCore ⟨e₀, before.pos.pushProj⟩ ⟨e₁, after.pos.pushProj⟩
| _, _ => return ExprDiff.withChange before after
where
piDiff (before after : SubExpr) : MetaM ExprDiff := do
let .forallE n₀ d₀ b₀ i₀ := before.expr
| return ∅
if let .forallE n₁ d₁ b₁ i₁ := after.expr then
if n₀ == n₁ && i₀ == i₁ then
-- assume that these are the same binders
let δd ← exprDiffCore
⟨d₀, before.pos.pushBindingDomain⟩
⟨d₁, after.pos.pushBindingDomain⟩
if δd.isEmpty then
-- the types have changed, so we can no longer meaningfully compare the targets
let δt ← Lean.Meta.withLocalDecl n₀ i₀ d₀ fun x =>
exprDiffCore
⟨b₀.instantiate1 x, before.pos.pushBindingBody⟩
⟨b₁.instantiate1 x, after.pos.pushBindingBody⟩
return δt
else
return δd ++ ExprDiff.withChangePos before.pos.pushBindingBody after.pos.pushBindingBody
-- in this case, the after expression does not match the before expression.
-- however, a special case is intros:
if let some s := List.isSuffixOf? after.expr.getForallBinderNames before.expr.getForallBinderNames then
-- s ++ namesAfter = namesBefore
if s.length == 0 then
throwError "should not happen"
let body₀ := before.expr.getForallBodyMaxDepth s.length
let mut δ : ExprDiff ← (do
-- this line can fail if we are using `before`'s mvar context, in which case
-- we can skip giving a diff.
let fvars ← s.mapM Lean.Meta.getFVarFromUserName
return ← exprDiffCore
⟨body₀.instantiateRev fvars.toArray, before.pos.pushNthBindingBody s.length⟩
after
) <|> (pure ∅)
for i in [0:s.length] do
δ := δ.insertBeforeChange (before.pos.pushNthBindingDomain i) .delete
-- [todo] maybe here insert a tag on the after case indicating an expression was deleted above the expression?
return δ
return ExprDiff.withChange before after
/-- Computes the diff for `e₀` and `e₁`. If `useAfter` is `false`, `e₀, e₁` are interpreted as `after, before` instead of `before, after`.-/
def exprDiff (e₀ e₁ : Expr) (useAfter := true) : MetaM ExprDiff := do
let s₀ := ⟨e₀, Pos.root⟩
let s₁ := ⟨e₁, Pos.root⟩
if useAfter then
exprDiffCore s₀ s₁
else
exprDiffCore s₁ s₀
/-- Given a `diff` between `before` and `after : Expr`, and the rendered `infoAfter : CodeWithInfos` for `after`,
this function decorates `infoAfter` with tags indicating where the expression has changed.
If `useAfter == false` before and after are swapped. -/
def addDiffTags (useAfter : Bool) (diff : ExprDiff) (info₁ : CodeWithInfos) : MetaM CodeWithInfos := do
let cs := if useAfter then diff.changesAfter else diff.changesBefore
info₁.mergePosMap (fun info d => pure <| info.withDiffTag <| ExprDiffTag.toDiffTag useAfter d) cs
open Meta
/-- Diffs the given hypothesis bundle against the given local context.
If `useAfter == true`, `ctx₀` is the context _before_ and `h₁` is the bundle _after_.
If `useAfter == false`, these are swapped.
-/
def diffHypothesesBundle (useAfter : Bool) (ctx₀ : LocalContext) (h₁ : InteractiveHypothesisBundle) : MetaM InteractiveHypothesisBundle := do
/- Strategy: we say a hypothesis has mutated if the ppName is the same but the fvarid has changed.
this indicates that something like `rewrite at` has hit it. -/
for (ppName, fvid) in Array.zip h₁.names h₁.fvarIds do
if !(ctx₀.contains fvid) then
if let some decl₀ := ctx₀.findFromUserName? ppName then
-- on ctx₀ there is an fvar with the same name as this one.
let t₀ := decl₀.type
return ← withTypeDiff t₀ h₁
else
if useAfter then
return {h₁ with isInserted? := true }
else
return {h₁ with isRemoved? := true }
-- all fvids are present on original so we can assume no change.
return h₁
where
withTypeDiff (t₀ : Expr) (h₁ : InteractiveHypothesisBundle) : MetaM InteractiveHypothesisBundle := do
let some x₁ := h₁.fvarIds[0]?
| throwError "internal error: empty fvar list!"
let t₁ ← inferType <| Expr.fvar x₁
let tδ ← exprDiff t₀ t₁ useAfter
let c₁ ← addDiffTags useAfter tδ h₁.type
return {h₁ with type := c₁}
def diffHypotheses (useAfter : Bool) (lctx₀ : LocalContext) (hs₁ : Array InteractiveHypothesisBundle) : MetaM (Array InteractiveHypothesisBundle) := do
-- [todo] also show when hypotheses (user-names present in lctx₀ but not in hs₁) are deleted
hs₁.mapM (diffHypothesesBundle useAfter lctx₀)
/-- Decorates the given goal `i₁` with a diff by comparing with goal `g₀`.
If `useAfter` is true then `i₁` is _after_ and `g₀` is _before_. Otherwise they are swapped. -/
def diffInteractiveGoal (useAfter : Bool) (g₀ : MVarId) (i₁ : InteractiveGoal) : MetaM InteractiveGoal := do
let mctx ← getMCtx
let some md₀ := mctx.findDecl? g₀
| throwError "Failed to find decl for {g₀}."
let lctx₀ := md₀.lctx |>.sanitizeNames.run' {options := (← getOptions)}
let hs₁ ← diffHypotheses useAfter lctx₀ i₁.hyps
let i₁ := {i₁ with hyps := hs₁}
let g₁ := i₁.mvarId
let t₀ ← instantiateMVars <|← inferType (Expr.mvar g₀)
let some md₁ := (← getMCtx).findDecl? g₁
| throwError "Unknown goal {g₁}"
let t₁ ← instantiateMVars md₁.type
let tδ ← exprDiff t₀ t₁ useAfter
let c₁ ← addDiffTags useAfter tδ i₁.type
let i₁ := {i₁ with type := c₁, isInserted? := false}
return i₁
/-- Modifies `goalsAfter` with additional information about how it is different to `goalsBefore`.
If `useAfter` is `true` then `igs₁` is the set of interactive goals _after_ the tactic has been applied.
Otherwise `igs₁` is the set of interactive goals _before_. -/
def diffInteractiveGoals (useAfter : Bool) (info : Elab.TacticInfo) (igs₁ : InteractiveGoals) : MetaM InteractiveGoals := do
if ! showTacticDiff.get (← getOptions) then return igs₁ else
let goals₀ := if useAfter then info.goalsBefore else info.goalsAfter
let parentMap : MVarIdMap MVarIdSet ← info.goalsBefore.foldlM (init := ∅) (fun s g => do
let ms ← Expr.mvar g |> Lean.Meta.getMVars
let ms : MVarIdSet := RBTree.fromArray ms _
return s.insert g ms
)
let isParent (before after : MVarId) : Bool :=
match parentMap.find? before with
| some xs => xs.contains after
| none => false
let goals ← igs₁.goals.mapM (fun ig₁ => do
let g₁ := ig₁.mvarId
withGoalCtx (g₁ : MVarId) (fun _lctx₁ _md₁ => do
-- if the goal is present on the previous version then continue
if goals₀.any (fun g₀ => g₀ == g₁) then
return {ig₁ with isInserted? := none}
let some g₀ := goals₀.find? (fun g₀ => if useAfter then isParent g₀ g₁ else isParent g₁ g₀)
| return if useAfter then {ig₁ with isInserted? := true } else {ig₁ with isRemoved? := true}
let ig₁ ← diffInteractiveGoal useAfter g₀ ig₁
return ig₁
)
)
return {igs₁ with goals := goals}
end Lean.Widget
|
0fafdbe83d5a960959ddc702b6d709a65808fa4d | 57c233acf9386e610d99ed20ef139c5f97504ba3 | /src/group_theory/perm/option.lean | 04aea25f3131cace91e89e6f867338b4a8a756cc | [
"Apache-2.0"
] | permissive | robertylewis/mathlib | 3d16e3e6daf5ddde182473e03a1b601d2810952c | 1d13f5b932f5e40a8308e3840f96fc882fae01f0 | refs/heads/master | 1,651,379,945,369 | 1,644,276,960,000 | 1,644,276,960,000 | 98,875,504 | 0 | 0 | Apache-2.0 | 1,644,253,514,000 | 1,501,495,700,000 | Lean | UTF-8 | Lean | false | false | 3,759 | lean | /-
Copyright (c) 2021 Eric Wieser. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Eric Wieser
-/
import group_theory.perm.sign
import data.equiv.option
/-!
# Permutations of `option α`
-/
open equiv
lemma equiv_functor.map_equiv_option_injective {α β : Type*} :
function.injective (equiv_functor.map_equiv option : α ≃ β → option α ≃ option β) :=
equiv_functor.map_equiv.injective option option.some_injective
@[simp] lemma equiv_functor.option.map_none {α β : Type*} (e : α ≃ β) :
equiv_functor.map e none = none :=
by simp [equiv_functor.map]
@[simp] lemma map_equiv_option_one {α : Type*} : equiv_functor.map_equiv option (1 : perm α) = 1 :=
by {ext, simp [equiv_functor.map_equiv, equiv_functor.map] }
@[simp] lemma map_equiv_option_refl {α : Type*} :
equiv_functor.map_equiv option (equiv.refl α) = 1 := map_equiv_option_one
@[simp] lemma map_equiv_option_swap {α : Type*} [decidable_eq α] (x y : α) :
equiv_functor.map_equiv option (swap x y) = swap (some x) (some y) :=
begin
ext (_ | i),
{ simp [swap_apply_of_ne_of_ne] },
{ by_cases hx : i = x,
simp [hx, swap_apply_of_ne_of_ne, equiv_functor.map],
by_cases hy : i = y;
simp [hx, hy, swap_apply_of_ne_of_ne, equiv_functor.map], }
end
@[simp] lemma equiv_functor.option.sign {α : Type*} [decidable_eq α] [fintype α] (e : perm α) :
perm.sign (equiv_functor.map_equiv option e) = perm.sign e :=
begin
apply perm.swap_induction_on e,
{ simp [perm.one_def] },
{ intros f x y hne h,
simp [h, hne, perm.mul_def, ←equiv_functor.map_equiv_trans] }
end
@[simp] lemma map_equiv_remove_none {α : Type*} [decidable_eq α] (σ : perm (option α)) :
equiv_functor.map_equiv option (remove_none σ) = swap none (σ none) * σ :=
begin
ext1 x,
have : option.map ⇑(remove_none σ) x = (swap none (σ none)) (σ x),
{ cases x,
{ simp },
{ cases h : σ (some x),
{ simp [remove_none_none _ h], },
{ have hn : σ (some x) ≠ none := by simp [h],
have hσn : σ (some x) ≠ σ none := σ.injective.ne (by simp),
simp [remove_none_some _ ⟨_, h⟩, ←h, swap_apply_of_ne_of_ne hn hσn] } } },
simpa using this,
end
/-- Permutations of `option α` are equivalent to fixing an
`option α` and permuting the remaining with a `perm α`.
The fixed `option α` is swapped with `none`. -/
@[simps] def equiv.perm.decompose_option {α : Type*} [decidable_eq α] :
perm (option α) ≃ option α × perm α :=
{ to_fun := λ σ, (σ none, remove_none σ),
inv_fun := λ i, swap none i.1 * (equiv_functor.map_equiv option i.2),
left_inv := λ σ, by simp,
right_inv := λ ⟨x, σ⟩, begin
have : remove_none (swap none x * equiv_functor.map_equiv option σ) = σ :=
equiv_functor.map_equiv_option_injective (by simp [←mul_assoc, equiv_functor.map]),
simp [←perm.eq_inv_iff_eq, equiv_functor.map, this],
end }
lemma equiv.perm.decompose_option_symm_of_none_apply {α : Type*} [decidable_eq α]
(e : perm α) (i : option α) :
equiv.perm.decompose_option.symm (none, e) i = i.map e :=
by simp [equiv_functor.map]
lemma equiv.perm.decompose_option_symm_sign {α : Type*} [decidable_eq α] [fintype α] (e : perm α) :
perm.sign (equiv.perm.decompose_option.symm (none, e)) = perm.sign e :=
by simp
/-- The set of all permutations of `option α` can be constructed by augmenting the set of
permutations of `α` by each element of `option α` in turn. -/
lemma finset.univ_perm_option {α : Type*} [decidable_eq α] [fintype α] :
@finset.univ (perm $ option α) _ =
(finset.univ : finset $ option α × perm α).map equiv.perm.decompose_option.symm.to_embedding :=
(finset.univ_map_equiv_to_embedding _).symm
|
a2649cef64d65e4d6fdd2531c1d7eb8d54933ddf | 88892181780ff536a81e794003fe058062f06758 | /src/100_theorems/t002.lean | 22942202c7770f85a604932956ac1c6e46f49db4 | [] | no_license | AtnNn/lean-sandbox | fe2c44280444e8bb8146ab8ac391c82b480c0a2e | 8c68afbdc09213173aef1be195da7a9a86060a97 | refs/heads/master | 1,623,004,395,876 | 1,579,969,507,000 | 1,579,969,507,000 | 146,666,368 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 176 | lean | import analysis.complex.polynomial
open polynomial
open complex
theorem t002 {f : polynomial ℂ} : (0 < degree f) → ∃ z : ℂ, is_root f z :=
exists_root
#check t002
|
26cdcdbe901f67c6af3d4c384f0abd29e7409e2f | 592ee40978ac7604005a4e0d35bbc4b467389241 | /Library/generated/mathscheme-lean/AssociativeLeftRingoid.lean | beadb6f8110d420eb64110e2a6ddab83a622cf4c | [] | no_license | ysharoda/Deriving-Definitions | 3e149e6641fae440badd35ac110a0bd705a49ad2 | dfecb27572022de3d4aa702cae8db19957523a59 | refs/heads/master | 1,679,127,857,700 | 1,615,939,007,000 | 1,615,939,007,000 | 229,785,731 | 4 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 9,890 | lean | import init.data.nat.basic
import init.data.fin.basic
import data.vector
import .Prelude
open Staged
open nat
open fin
open vector
section AssociativeLeftRingoid
structure AssociativeLeftRingoid (A : Type) : Type :=
(times : (A → (A → A)))
(associative_times : (∀ {x y z : A} , (times (times x y) z) = (times x (times y z))))
(plus : (A → (A → A)))
(leftDistributive_times_plus : (∀ {x y z : A} , (times x (plus y z)) = (plus (times x y) (times x z))))
open AssociativeLeftRingoid
structure Sig (AS : Type) : Type :=
(timesS : (AS → (AS → AS)))
(plusS : (AS → (AS → AS)))
structure Product (A : Type) : Type :=
(timesP : ((Prod A A) → ((Prod A A) → (Prod A A))))
(plusP : ((Prod A A) → ((Prod A A) → (Prod A A))))
(associative_timesP : (∀ {xP yP zP : (Prod A A)} , (timesP (timesP xP yP) zP) = (timesP xP (timesP yP zP))))
(leftDistributive_times_plusP : (∀ {xP yP zP : (Prod A A)} , (timesP xP (plusP yP zP)) = (plusP (timesP xP yP) (timesP xP zP))))
structure Hom {A1 : Type} {A2 : Type} (As1 : (AssociativeLeftRingoid A1)) (As2 : (AssociativeLeftRingoid A2)) : Type :=
(hom : (A1 → A2))
(pres_times : (∀ {x1 x2 : A1} , (hom ((times As1) x1 x2)) = ((times As2) (hom x1) (hom x2))))
(pres_plus : (∀ {x1 x2 : A1} , (hom ((plus As1) x1 x2)) = ((plus As2) (hom x1) (hom x2))))
structure RelInterp {A1 : Type} {A2 : Type} (As1 : (AssociativeLeftRingoid A1)) (As2 : (AssociativeLeftRingoid A2)) : Type 1 :=
(interp : (A1 → (A2 → Type)))
(interp_times : (∀ {x1 x2 : A1} {y1 y2 : A2} , ((interp x1 y1) → ((interp x2 y2) → (interp ((times As1) x1 x2) ((times As2) y1 y2))))))
(interp_plus : (∀ {x1 x2 : A1} {y1 y2 : A2} , ((interp x1 y1) → ((interp x2 y2) → (interp ((plus As1) x1 x2) ((plus As2) y1 y2))))))
inductive AssociativeLeftRingoidTerm : Type
| timesL : (AssociativeLeftRingoidTerm → (AssociativeLeftRingoidTerm → AssociativeLeftRingoidTerm))
| plusL : (AssociativeLeftRingoidTerm → (AssociativeLeftRingoidTerm → AssociativeLeftRingoidTerm))
open AssociativeLeftRingoidTerm
inductive ClAssociativeLeftRingoidTerm (A : Type) : Type
| sing : (A → ClAssociativeLeftRingoidTerm)
| timesCl : (ClAssociativeLeftRingoidTerm → (ClAssociativeLeftRingoidTerm → ClAssociativeLeftRingoidTerm))
| plusCl : (ClAssociativeLeftRingoidTerm → (ClAssociativeLeftRingoidTerm → ClAssociativeLeftRingoidTerm))
open ClAssociativeLeftRingoidTerm
inductive OpAssociativeLeftRingoidTerm (n : ℕ) : Type
| v : ((fin n) → OpAssociativeLeftRingoidTerm)
| timesOL : (OpAssociativeLeftRingoidTerm → (OpAssociativeLeftRingoidTerm → OpAssociativeLeftRingoidTerm))
| plusOL : (OpAssociativeLeftRingoidTerm → (OpAssociativeLeftRingoidTerm → OpAssociativeLeftRingoidTerm))
open OpAssociativeLeftRingoidTerm
inductive OpAssociativeLeftRingoidTerm2 (n : ℕ) (A : Type) : Type
| v2 : ((fin n) → OpAssociativeLeftRingoidTerm2)
| sing2 : (A → OpAssociativeLeftRingoidTerm2)
| timesOL2 : (OpAssociativeLeftRingoidTerm2 → (OpAssociativeLeftRingoidTerm2 → OpAssociativeLeftRingoidTerm2))
| plusOL2 : (OpAssociativeLeftRingoidTerm2 → (OpAssociativeLeftRingoidTerm2 → OpAssociativeLeftRingoidTerm2))
open OpAssociativeLeftRingoidTerm2
def simplifyCl {A : Type} : ((ClAssociativeLeftRingoidTerm A) → (ClAssociativeLeftRingoidTerm A))
| (timesCl x1 x2) := (timesCl (simplifyCl x1) (simplifyCl x2))
| (plusCl x1 x2) := (plusCl (simplifyCl x1) (simplifyCl x2))
| (sing x1) := (sing x1)
def simplifyOpB {n : ℕ} : ((OpAssociativeLeftRingoidTerm n) → (OpAssociativeLeftRingoidTerm n))
| (timesOL x1 x2) := (timesOL (simplifyOpB x1) (simplifyOpB x2))
| (plusOL x1 x2) := (plusOL (simplifyOpB x1) (simplifyOpB x2))
| (v x1) := (v x1)
def simplifyOp {n : ℕ} {A : Type} : ((OpAssociativeLeftRingoidTerm2 n A) → (OpAssociativeLeftRingoidTerm2 n A))
| (timesOL2 x1 x2) := (timesOL2 (simplifyOp x1) (simplifyOp x2))
| (plusOL2 x1 x2) := (plusOL2 (simplifyOp x1) (simplifyOp x2))
| (v2 x1) := (v2 x1)
| (sing2 x1) := (sing2 x1)
def evalB {A : Type} : ((AssociativeLeftRingoid A) → (AssociativeLeftRingoidTerm → A))
| As (timesL x1 x2) := ((times As) (evalB As x1) (evalB As x2))
| As (plusL x1 x2) := ((plus As) (evalB As x1) (evalB As x2))
def evalCl {A : Type} : ((AssociativeLeftRingoid A) → ((ClAssociativeLeftRingoidTerm A) → A))
| As (sing x1) := x1
| As (timesCl x1 x2) := ((times As) (evalCl As x1) (evalCl As x2))
| As (plusCl x1 x2) := ((plus As) (evalCl As x1) (evalCl As x2))
def evalOpB {A : Type} {n : ℕ} : ((AssociativeLeftRingoid A) → ((vector A n) → ((OpAssociativeLeftRingoidTerm n) → A)))
| As vars (v x1) := (nth vars x1)
| As vars (timesOL x1 x2) := ((times As) (evalOpB As vars x1) (evalOpB As vars x2))
| As vars (plusOL x1 x2) := ((plus As) (evalOpB As vars x1) (evalOpB As vars x2))
def evalOp {A : Type} {n : ℕ} : ((AssociativeLeftRingoid A) → ((vector A n) → ((OpAssociativeLeftRingoidTerm2 n A) → A)))
| As vars (v2 x1) := (nth vars x1)
| As vars (sing2 x1) := x1
| As vars (timesOL2 x1 x2) := ((times As) (evalOp As vars x1) (evalOp As vars x2))
| As vars (plusOL2 x1 x2) := ((plus As) (evalOp As vars x1) (evalOp As vars x2))
def inductionB {P : (AssociativeLeftRingoidTerm → Type)} : ((∀ (x1 x2 : AssociativeLeftRingoidTerm) , ((P x1) → ((P x2) → (P (timesL x1 x2))))) → ((∀ (x1 x2 : AssociativeLeftRingoidTerm) , ((P x1) → ((P x2) → (P (plusL x1 x2))))) → (∀ (x : AssociativeLeftRingoidTerm) , (P x))))
| ptimesl pplusl (timesL x1 x2) := (ptimesl _ _ (inductionB ptimesl pplusl x1) (inductionB ptimesl pplusl x2))
| ptimesl pplusl (plusL x1 x2) := (pplusl _ _ (inductionB ptimesl pplusl x1) (inductionB ptimesl pplusl x2))
def inductionCl {A : Type} {P : ((ClAssociativeLeftRingoidTerm A) → Type)} : ((∀ (x1 : A) , (P (sing x1))) → ((∀ (x1 x2 : (ClAssociativeLeftRingoidTerm A)) , ((P x1) → ((P x2) → (P (timesCl x1 x2))))) → ((∀ (x1 x2 : (ClAssociativeLeftRingoidTerm A)) , ((P x1) → ((P x2) → (P (plusCl x1 x2))))) → (∀ (x : (ClAssociativeLeftRingoidTerm A)) , (P x)))))
| psing ptimescl ppluscl (sing x1) := (psing x1)
| psing ptimescl ppluscl (timesCl x1 x2) := (ptimescl _ _ (inductionCl psing ptimescl ppluscl x1) (inductionCl psing ptimescl ppluscl x2))
| psing ptimescl ppluscl (plusCl x1 x2) := (ppluscl _ _ (inductionCl psing ptimescl ppluscl x1) (inductionCl psing ptimescl ppluscl x2))
def inductionOpB {n : ℕ} {P : ((OpAssociativeLeftRingoidTerm n) → Type)} : ((∀ (fin : (fin n)) , (P (v fin))) → ((∀ (x1 x2 : (OpAssociativeLeftRingoidTerm n)) , ((P x1) → ((P x2) → (P (timesOL x1 x2))))) → ((∀ (x1 x2 : (OpAssociativeLeftRingoidTerm n)) , ((P x1) → ((P x2) → (P (plusOL x1 x2))))) → (∀ (x : (OpAssociativeLeftRingoidTerm n)) , (P x)))))
| pv ptimesol pplusol (v x1) := (pv x1)
| pv ptimesol pplusol (timesOL x1 x2) := (ptimesol _ _ (inductionOpB pv ptimesol pplusol x1) (inductionOpB pv ptimesol pplusol x2))
| pv ptimesol pplusol (plusOL x1 x2) := (pplusol _ _ (inductionOpB pv ptimesol pplusol x1) (inductionOpB pv ptimesol pplusol x2))
def inductionOp {n : ℕ} {A : Type} {P : ((OpAssociativeLeftRingoidTerm2 n A) → Type)} : ((∀ (fin : (fin n)) , (P (v2 fin))) → ((∀ (x1 : A) , (P (sing2 x1))) → ((∀ (x1 x2 : (OpAssociativeLeftRingoidTerm2 n A)) , ((P x1) → ((P x2) → (P (timesOL2 x1 x2))))) → ((∀ (x1 x2 : (OpAssociativeLeftRingoidTerm2 n A)) , ((P x1) → ((P x2) → (P (plusOL2 x1 x2))))) → (∀ (x : (OpAssociativeLeftRingoidTerm2 n A)) , (P x))))))
| pv2 psing2 ptimesol2 pplusol2 (v2 x1) := (pv2 x1)
| pv2 psing2 ptimesol2 pplusol2 (sing2 x1) := (psing2 x1)
| pv2 psing2 ptimesol2 pplusol2 (timesOL2 x1 x2) := (ptimesol2 _ _ (inductionOp pv2 psing2 ptimesol2 pplusol2 x1) (inductionOp pv2 psing2 ptimesol2 pplusol2 x2))
| pv2 psing2 ptimesol2 pplusol2 (plusOL2 x1 x2) := (pplusol2 _ _ (inductionOp pv2 psing2 ptimesol2 pplusol2 x1) (inductionOp pv2 psing2 ptimesol2 pplusol2 x2))
def stageB : (AssociativeLeftRingoidTerm → (Staged AssociativeLeftRingoidTerm))
| (timesL x1 x2) := (stage2 timesL (codeLift2 timesL) (stageB x1) (stageB x2))
| (plusL x1 x2) := (stage2 plusL (codeLift2 plusL) (stageB x1) (stageB x2))
def stageCl {A : Type} : ((ClAssociativeLeftRingoidTerm A) → (Staged (ClAssociativeLeftRingoidTerm A)))
| (sing x1) := (Now (sing x1))
| (timesCl x1 x2) := (stage2 timesCl (codeLift2 timesCl) (stageCl x1) (stageCl x2))
| (plusCl x1 x2) := (stage2 plusCl (codeLift2 plusCl) (stageCl x1) (stageCl x2))
def stageOpB {n : ℕ} : ((OpAssociativeLeftRingoidTerm n) → (Staged (OpAssociativeLeftRingoidTerm n)))
| (v x1) := (const (code (v x1)))
| (timesOL x1 x2) := (stage2 timesOL (codeLift2 timesOL) (stageOpB x1) (stageOpB x2))
| (plusOL x1 x2) := (stage2 plusOL (codeLift2 plusOL) (stageOpB x1) (stageOpB x2))
def stageOp {n : ℕ} {A : Type} : ((OpAssociativeLeftRingoidTerm2 n A) → (Staged (OpAssociativeLeftRingoidTerm2 n A)))
| (sing2 x1) := (Now (sing2 x1))
| (v2 x1) := (const (code (v2 x1)))
| (timesOL2 x1 x2) := (stage2 timesOL2 (codeLift2 timesOL2) (stageOp x1) (stageOp x2))
| (plusOL2 x1 x2) := (stage2 plusOL2 (codeLift2 plusOL2) (stageOp x1) (stageOp x2))
structure StagedRepr (A : Type) (Repr : (Type → Type)) : Type :=
(timesT : ((Repr A) → ((Repr A) → (Repr A))))
(plusT : ((Repr A) → ((Repr A) → (Repr A))))
end AssociativeLeftRingoid |
8e974a8b3d07dbf041d349cc7b90ce1ddce2319b | 4d2583807a5ac6caaffd3d7a5f646d61ca85d532 | /src/data/finset/basic.lean | e173837a4b15d9665237fa28d4f358466f90e4d9 | [
"Apache-2.0"
] | permissive | AntoineChambert-Loir/mathlib | 64aabb896129885f12296a799818061bc90da1ff | 07be904260ab6e36a5769680b6012f03a4727134 | refs/heads/master | 1,693,187,631,771 | 1,636,719,886,000 | 1,636,719,886,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 129,955 | lean | /-
Copyright (c) 2015 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura, Jeremy Avigad, Minchao Wu, Mario Carneiro
-/
import data.multiset.finset_ops
import tactic.apply
import tactic.monotonicity
import tactic.nth_rewrite
/-!
# Finite sets
Terms of type `finset α` are one way of talking about finite subsets of `α` in mathlib.
Below, `finset α` is defined as a structure with 2 fields:
1. `val` is a `multiset α` of elements;
2. `nodup` is a proof that `val` has no duplicates.
Finsets in Lean are constructive in that they have an underlying `list` that enumerates their
elements. In particular, any function that uses the data of the underlying list cannot depend on its
ordering. This is handled on the `multiset` level by multiset API, so in most cases one needn't
worry about it explicitly.
Finsets give a basic foundation for defining finite sums and products over types:
1. `∑ i in (s : finset α), f i`;
2. `∏ i in (s : finset α), f i`.
Lean refers to these operations as `big_operator`s.
More information can be found in `algebra.big_operators.basic`.
Finsets are directly used to define fintypes in Lean.
A `fintype α` instance for a type `α` consists of
a universal `finset α` containing every term of `α`, called `univ`. See `data.fintype.basic`.
There is also `univ'`, the noncomputable partner to `univ`,
which is defined to be `α` as a finset if `α` is finite,
and the empty finset otherwise. See `data.fintype.basic`.
## Main declarations
### Main definitions
* `finset`: Defines a type for the finite subsets of `α`.
Constructing a `finset` requires two pieces of data: `val`, a `multiset α` of elements,
and `nodup`, a proof that `val` has no duplicates.
* `finset.has_mem`: Defines membership `a ∈ (s : finset α)`.
* `finset.has_coe`: Provides a coercion `s : finset α` to `s : set α`.
* `finset.has_coe_to_sort`: Coerce `s : finset α` to the type of all `x ∈ s`.
* `finset.induction_on`: Induction on finsets. To prove a proposition about an arbitrary `finset α`,
it suffices to prove it for the empty finset, and to show that if it holds for some `finset α`,
then it holds for the finset obtained by inserting a new element.
* `finset.choose`: Given a proof `h` of existence and uniqueness of a certain element
satisfying a predicate, `choose s h` returns the element of `s` satisfying that predicate.
* `finset.card`: `card s : ℕ` returns the cardinalilty of `s : finset α`.
The API for `card`'s interaction with operations on finsets is extensive.
TODO: The noncomputable sister `fincard` is about to be added into mathlib.
### Finset constructions
* `singleton`: Denoted by `{a}`; the finset consisting of one element.
* `finset.empty`: Denoted by `∅`. The finset associated to any type consisting of no elements.
* `finset.range`: For any `n : ℕ`, `range n` is equal to `{0, 1, ... , n - 1} ⊆ ℕ`.
This convention is consistent with other languages and normalizes `card (range n) = n`.
Beware, `n` is not in `range n`.
* `finset.attach`: Given `s : finset α`, `attach s` forms a finset of elements of the subtype
`{a // a ∈ s}`; in other words, it attaches elements to a proof of membership in the set.
### Finsets from functions
* `finset.image`: Given a function `f : α → β`, `s.image f` is the image finset in `β`.
* `finset.map`: Given an embedding `f : α ↪ β`, `s.map f` is the image finset in `β`.
* `finset.filter`: Given a predicate `p : α → Prop`, `s.filter p` is
the finset consisting of those elements in `s` satisfying the predicate `p`.
### The lattice structure on subsets of finsets
There is a natural lattice structure on the subsets of a set.
In Lean, we use lattice notation to talk about things involving unions and intersections. See
`order.lattice`. For the lattice structure on finsets, `⊥` is called `bot` with `⊥ = ∅` and `⊤` is
called `top` with `⊤ = univ`.
* `finset.subset`: Lots of API about lattices, otherwise behaves exactly as one would expect.
* `finset.union`: Defines `s ∪ t` (or `s ⊔ t`) as the union of `s` and `t`.
See `finset.sup`/`finset.bUnion` for finite unions.
* `finset.inter`: Defines `s ∩ t` (or `s ⊓ t`) as the intersection of `s` and `t`.
See `finset.inf` for finite intersections.
* `finset.disj_union`: Given a hypothesis `h` which states that finsets `s` and `t` are disjoint,
`s.disj_union t h` is the set such that `a ∈ disj_union s t h` iff `a ∈ s` or `a ∈ t`; this does
not require decidable equality on the type `α`.
### Operations on two or more finsets
* `finset.insert` and `finset.cons`: For any `a : α`, `insert s a` returns `s ∪ {a}`. `cons s a h`
returns the same except that it requires a hypothesis stating that `a` is not already in `s`.
This does not require decidable equality on the type `α`.
* `finset.union`: see "The lattice structure on subsets of finsets"
* `finset.inter`: see "The lattice structure on subsets of finsets"
* `finset.erase`: For any `a : α`, `erase s a` returns `s` with the element `a` removed.
* `finset.sdiff`: Defines the set difference `s \ t` for finsets `s` and `t`.
* `finset.prod`: Given finsets of `α` and `β`, defines finsets of `α × β`.
For arbitrary dependent products, see `data.finset.pi`.
* `finset.sigma`: Given finsets of `α` and `β`, defines finsets of the dependent sum type `Σ α, β`
* `finset.bUnion`: Finite unions of finsets; given an indexing function `f : α → finset β` and a
`s : finset α`, `s.bUnion f` is the union of all finsets of the form `f a` for `a ∈ s`.
* `finset.bInter`: TODO: Implemement finite intersections.
### Maps constructed using finsets
* `finset.piecewise`: Given two functions `f`, `g`, `s.piecewise f g` is a function which is equal
to `f` on `s` and `g` on the complement.
### Predicates on finsets
* `disjoint`: defined via the lattice structure on finsets; two sets are disjoint if their
intersection is empty.
* `finset.nonempty`: A finset is nonempty if it has elements.
This is equivalent to saying `s ≠ ∅`. TODO: Decide on the simp normal form.
### Equivalences between finsets
* The `data.equiv` files describe a general type of equivalence, so look in there for any lemmas.
There is some API for rewriting sums and products from `s` to `t` given that `s ≃ t`.
TODO: examples
## Tags
finite sets, finset
-/
open multiset subtype nat function
universes u
variables {α : Type*} {β : Type*} {γ : Type*}
/-- `finset α` is the type of finite sets of elements of `α`. It is implemented
as a multiset (a list up to permutation) which has no duplicate elements. -/
structure finset (α : Type*) :=
(val : multiset α)
(nodup : nodup val)
namespace finset
theorem eq_of_veq : ∀ {s t : finset α}, s.1 = t.1 → s = t
| ⟨s, _⟩ ⟨t, _⟩ rfl := rfl
@[simp] theorem val_inj {s t : finset α} : s.1 = t.1 ↔ s = t :=
⟨eq_of_veq, congr_arg _⟩
@[simp] theorem erase_dup_eq_self [decidable_eq α] (s : finset α) : erase_dup s.1 = s.1 :=
s.2.erase_dup
instance has_decidable_eq [decidable_eq α] : decidable_eq (finset α)
| s₁ s₂ := decidable_of_iff _ val_inj
/-! ### membership -/
instance : has_mem α (finset α) := ⟨λ a s, a ∈ s.1⟩
theorem mem_def {a : α} {s : finset α} : a ∈ s ↔ a ∈ s.1 := iff.rfl
@[simp] theorem mem_mk {a : α} {s nd} : a ∈ @finset.mk α s nd ↔ a ∈ s := iff.rfl
instance decidable_mem [h : decidable_eq α] (a : α) (s : finset α) : decidable (a ∈ s) :=
multiset.decidable_mem _ _
/-! ### set coercion -/
/-- Convert a finset to a set in the natural way. -/
instance : has_coe_t (finset α) (set α) := ⟨λ s, {x | x ∈ s}⟩
@[simp, norm_cast] lemma mem_coe {a : α} {s : finset α} : a ∈ (s : set α) ↔ a ∈ s := iff.rfl
@[simp] lemma set_of_mem {α} {s : finset α} : {a | a ∈ s} = s := rfl
@[simp] lemma coe_mem {s : finset α} (x : (s : set α)) : ↑x ∈ s := x.2
@[simp] lemma mk_coe {s : finset α} (x : (s : set α)) {h} :
(⟨x, h⟩ : (s : set α)) = x :=
subtype.coe_eta _ _
instance decidable_mem' [decidable_eq α] (a : α) (s : finset α) :
decidable (a ∈ (s : set α)) := s.decidable_mem _
/-! ### extensionality -/
theorem ext_iff {s₁ s₂ : finset α} : s₁ = s₂ ↔ ∀ a, a ∈ s₁ ↔ a ∈ s₂ :=
val_inj.symm.trans $ nodup_ext s₁.2 s₂.2
@[ext]
theorem ext {s₁ s₂ : finset α} : (∀ a, a ∈ s₁ ↔ a ∈ s₂) → s₁ = s₂ :=
ext_iff.2
@[simp, norm_cast] theorem coe_inj {s₁ s₂ : finset α} : (s₁ : set α) = s₂ ↔ s₁ = s₂ :=
set.ext_iff.trans ext_iff.symm
lemma coe_injective {α} : injective (coe : finset α → set α) :=
λ s t, coe_inj.1
/-! ### type coercion -/
/-- Coercion from a finset to the corresponding subtype. -/
instance {α : Type u} : has_coe_to_sort (finset α) (Type u) := ⟨λ s, {x // x ∈ s}⟩
instance pi_finset_coe.can_lift (ι : Type*) (α : Π i : ι, Type*) [ne : Π i, nonempty (α i)]
(s : finset ι) :
can_lift (Π i : s, α i) (Π i, α i) :=
{ coe := λ f i, f i,
.. pi_subtype.can_lift ι α (∈ s) }
instance pi_finset_coe.can_lift' (ι α : Type*) [ne : nonempty α] (s : finset ι) :
can_lift (s → α) (ι → α) :=
pi_finset_coe.can_lift ι (λ _, α) s
instance finset_coe.can_lift (s : finset α) : can_lift α s :=
{ coe := coe,
cond := λ a, a ∈ s,
prf := λ a ha, ⟨⟨a, ha⟩, rfl⟩ }
@[simp, norm_cast] lemma coe_sort_coe (s : finset α) :
((s : set α) : Sort*) = s := rfl
/-! ### subset -/
instance : has_subset (finset α) := ⟨λ s₁ s₂, ∀ ⦃a⦄, a ∈ s₁ → a ∈ s₂⟩
theorem subset_def {s₁ s₂ : finset α} : s₁ ⊆ s₂ ↔ s₁.1 ⊆ s₂.1 := iff.rfl
@[simp] theorem subset.refl (s : finset α) : s ⊆ s := subset.refl _
theorem subset_of_eq {s t : finset α} (h : s = t) : s ⊆ t := h ▸ subset.refl _
theorem subset.trans {s₁ s₂ s₃ : finset α} : s₁ ⊆ s₂ → s₂ ⊆ s₃ → s₁ ⊆ s₃ := subset.trans
theorem superset.trans {s₁ s₂ s₃ : finset α} : s₁ ⊇ s₂ → s₂ ⊇ s₃ → s₁ ⊇ s₃ :=
λ h' h, subset.trans h h'
-- TODO: these should be global attributes, but this will require fixing other files
local attribute [trans] subset.trans superset.trans
theorem mem_of_subset {s₁ s₂ : finset α} {a : α} : s₁ ⊆ s₂ → a ∈ s₁ → a ∈ s₂ := mem_of_subset
theorem subset.antisymm {s₁ s₂ : finset α} (H₁ : s₁ ⊆ s₂) (H₂ : s₂ ⊆ s₁) : s₁ = s₂ :=
ext $ λ a, ⟨@H₁ a, @H₂ a⟩
theorem subset_iff {s₁ s₂ : finset α} : s₁ ⊆ s₂ ↔ ∀ ⦃x⦄, x ∈ s₁ → x ∈ s₂ := iff.rfl
@[simp, norm_cast] theorem coe_subset {s₁ s₂ : finset α} :
(s₁ : set α) ⊆ s₂ ↔ s₁ ⊆ s₂ := iff.rfl
@[simp] theorem val_le_iff {s₁ s₂ : finset α} : s₁.1 ≤ s₂.1 ↔ s₁ ⊆ s₂ := le_iff_subset s₁.2
instance : has_ssubset (finset α) := ⟨λa b, a ⊆ b ∧ ¬ b ⊆ a⟩
instance : partial_order (finset α) :=
{ le := (⊆),
lt := (⊂),
le_refl := subset.refl,
le_trans := @subset.trans _,
le_antisymm := @subset.antisymm _ }
/-- Coercion to `set α` as an `order_embedding`. -/
def coe_emb : finset α ↪o set α := ⟨⟨coe, coe_injective⟩, λ s t, coe_subset⟩
@[simp] lemma coe_coe_emb : ⇑(coe_emb : finset α ↪o set α) = coe := rfl
theorem subset.antisymm_iff {s₁ s₂ : finset α} : s₁ = s₂ ↔ s₁ ⊆ s₂ ∧ s₂ ⊆ s₁ :=
le_antisymm_iff
theorem not_subset (s t : finset α) : ¬(s ⊆ t) ↔ ∃ x ∈ s, ¬(x ∈ t) :=
by simp only [←finset.coe_subset, set.not_subset, exists_prop, finset.mem_coe]
@[simp] theorem le_eq_subset : ((≤) : finset α → finset α → Prop) = (⊆) := rfl
@[simp] theorem lt_eq_subset : ((<) : finset α → finset α → Prop) = (⊂) := rfl
theorem le_iff_subset {s₁ s₂ : finset α} : s₁ ≤ s₂ ↔ s₁ ⊆ s₂ := iff.rfl
theorem lt_iff_ssubset {s₁ s₂ : finset α} : s₁ < s₂ ↔ s₁ ⊂ s₂ := iff.rfl
@[simp, norm_cast] lemma coe_ssubset {s₁ s₂ : finset α} : (s₁ : set α) ⊂ s₂ ↔ s₁ ⊂ s₂ :=
show (s₁ : set α) ⊂ s₂ ↔ s₁ ⊆ s₂ ∧ ¬s₂ ⊆ s₁,
by simp only [set.ssubset_def, finset.coe_subset]
@[simp] theorem val_lt_iff {s₁ s₂ : finset α} : s₁.1 < s₂.1 ↔ s₁ ⊂ s₂ :=
and_congr val_le_iff $ not_congr val_le_iff
lemma ssubset_iff_subset_ne {s t : finset α} : s ⊂ t ↔ s ⊆ t ∧ s ≠ t :=
@lt_iff_le_and_ne _ _ s t
theorem ssubset_iff_of_subset {s₁ s₂ : finset α} (h : s₁ ⊆ s₂) : s₁ ⊂ s₂ ↔ ∃ x ∈ s₂, x ∉ s₁ :=
set.ssubset_iff_of_subset h
lemma ssubset_of_ssubset_of_subset {s₁ s₂ s₃ : finset α} (hs₁s₂ : s₁ ⊂ s₂) (hs₂s₃ : s₂ ⊆ s₃) :
s₁ ⊂ s₃ :=
set.ssubset_of_ssubset_of_subset hs₁s₂ hs₂s₃
lemma ssubset_of_subset_of_ssubset {s₁ s₂ s₃ : finset α} (hs₁s₂ : s₁ ⊆ s₂) (hs₂s₃ : s₂ ⊂ s₃) :
s₁ ⊂ s₃ :=
set.ssubset_of_subset_of_ssubset hs₁s₂ hs₂s₃
lemma exists_of_ssubset {s₁ s₂ : finset α} (h : s₁ ⊂ s₂) :
∃ x ∈ s₂, x ∉ s₁ :=
set.exists_of_ssubset h
/-! ### Nonempty -/
/-- The property `s.nonempty` expresses the fact that the finset `s` is not empty. It should be used
in theorem assumptions instead of `∃ x, x ∈ s` or `s ≠ ∅` as it gives access to a nice API thanks
to the dot notation. -/
protected def nonempty (s : finset α) : Prop := ∃ x:α, x ∈ s
@[simp, norm_cast] lemma coe_nonempty {s : finset α} : (s:set α).nonempty ↔ s.nonempty := iff.rfl
@[simp] lemma nonempty_coe_sort (s : finset α) : nonempty ↥s ↔ s.nonempty := nonempty_subtype
alias coe_nonempty ↔ _ finset.nonempty.to_set
lemma nonempty.bex {s : finset α} (h : s.nonempty) : ∃ x:α, x ∈ s := h
lemma nonempty.mono {s t : finset α} (hst : s ⊆ t) (hs : s.nonempty) : t.nonempty :=
set.nonempty.mono hst hs
lemma nonempty.forall_const {s : finset α} (h : s.nonempty) {p : Prop} : (∀ x ∈ s, p) ↔ p :=
let ⟨x, hx⟩ := h in ⟨λ h, h x hx, λ h x hx, h⟩
/-! ### empty -/
/-- The empty finset -/
protected def empty : finset α := ⟨0, nodup_zero⟩
instance : has_emptyc (finset α) := ⟨finset.empty⟩
instance inhabited_finset : inhabited (finset α) := ⟨∅⟩
@[simp] theorem empty_val : (∅ : finset α).1 = 0 := rfl
@[simp] theorem not_mem_empty (a : α) : a ∉ (∅ : finset α) := id
@[simp] theorem not_nonempty_empty : ¬(∅ : finset α).nonempty :=
λ ⟨x, hx⟩, not_mem_empty x hx
@[simp] theorem mk_zero : (⟨0, nodup_zero⟩ : finset α) = ∅ := rfl
theorem ne_empty_of_mem {a : α} {s : finset α} (h : a ∈ s) : s ≠ ∅ :=
λ e, not_mem_empty a $ e ▸ h
theorem nonempty.ne_empty {s : finset α} (h : s.nonempty) : s ≠ ∅ :=
exists.elim h $ λ a, ne_empty_of_mem
@[simp] theorem empty_subset (s : finset α) : ∅ ⊆ s := zero_subset _
theorem eq_empty_of_forall_not_mem {s : finset α} (H : ∀x, x ∉ s) : s = ∅ :=
eq_of_veq (eq_zero_of_forall_not_mem H)
lemma eq_empty_iff_forall_not_mem {s : finset α} : s = ∅ ↔ ∀ x, x ∉ s :=
⟨by rintro rfl x; exact id, λ h, eq_empty_of_forall_not_mem h⟩
@[simp] theorem val_eq_zero {s : finset α} : s.1 = 0 ↔ s = ∅ := @val_inj _ s ∅
theorem subset_empty {s : finset α} : s ⊆ ∅ ↔ s = ∅ := subset_zero.trans val_eq_zero
@[simp] lemma not_ssubset_empty (s : finset α) : ¬s ⊂ ∅ :=
λ h, let ⟨x, he, hs⟩ := exists_of_ssubset h in he
theorem nonempty_of_ne_empty {s : finset α} (h : s ≠ ∅) : s.nonempty :=
exists_mem_of_ne_zero (mt val_eq_zero.1 h)
theorem nonempty_iff_ne_empty {s : finset α} : s.nonempty ↔ s ≠ ∅ :=
⟨nonempty.ne_empty, nonempty_of_ne_empty⟩
@[simp] theorem not_nonempty_iff_eq_empty {s : finset α} : ¬s.nonempty ↔ s = ∅ :=
by { rw nonempty_iff_ne_empty, exact not_not, }
theorem eq_empty_or_nonempty (s : finset α) : s = ∅ ∨ s.nonempty :=
classical.by_cases or.inl (λ h, or.inr (nonempty_of_ne_empty h))
@[simp, norm_cast] lemma coe_empty : ((∅ : finset α) : set α) = ∅ := rfl
@[simp, norm_cast] lemma coe_eq_empty {s : finset α} :
(s : set α) = ∅ ↔ s = ∅ :=
by rw [← coe_empty, coe_inj]
/-- A `finset` for an empty type is empty. -/
lemma eq_empty_of_is_empty [is_empty α] (s : finset α) : s = ∅ :=
finset.eq_empty_of_forall_not_mem is_empty_elim
/-! ### singleton -/
/--
`{a} : finset a` is the set `{a}` containing `a` and nothing else.
This differs from `insert a ∅` in that it does not require a `decidable_eq` instance for `α`.
-/
instance : has_singleton α (finset α) := ⟨λ a, ⟨{a}, nodup_singleton a⟩⟩
@[simp] theorem singleton_val (a : α) : ({a} : finset α).1 = {a} := rfl
@[simp] theorem mem_singleton {a b : α} : b ∈ ({a} : finset α) ↔ b = a := mem_singleton
theorem not_mem_singleton {a b : α} : a ∉ ({b} : finset α) ↔ a ≠ b := not_congr mem_singleton
theorem mem_singleton_self (a : α) : a ∈ ({a} : finset α) := or.inl rfl
lemma singleton_injective : injective (singleton : α → finset α) :=
λ a b h, mem_singleton.1 (h ▸ mem_singleton_self _)
theorem singleton_inj {a b : α} : ({a} : finset α) = {b} ↔ a = b :=
singleton_injective.eq_iff
@[simp] theorem singleton_nonempty (a : α) : ({a} : finset α).nonempty := ⟨a, mem_singleton_self a⟩
@[simp] theorem singleton_ne_empty (a : α) : ({a} : finset α) ≠ ∅ := (singleton_nonempty a).ne_empty
@[simp, norm_cast] lemma coe_singleton (a : α) : (({a} : finset α) : set α) = {a} :=
by { ext, simp }
@[simp, norm_cast] lemma coe_eq_singleton {α : Type*} {s : finset α} {a : α} :
(s : set α) = {a} ↔ s = {a} :=
by rw [←finset.coe_singleton, finset.coe_inj]
lemma eq_singleton_iff_unique_mem {s : finset α} {a : α} :
s = {a} ↔ a ∈ s ∧ ∀ x ∈ s, x = a :=
begin
split; intro t,
rw t,
refine ⟨finset.mem_singleton_self _, λ _, finset.mem_singleton.1⟩,
ext, rw finset.mem_singleton,
refine ⟨t.right _, λ r, r.symm ▸ t.left⟩
end
lemma eq_singleton_iff_nonempty_unique_mem {s : finset α} {a : α} :
s = {a} ↔ s.nonempty ∧ ∀ x ∈ s, x = a :=
begin
split,
{ intros h, subst h, simp, },
{ rintros ⟨hne, h_uniq⟩, rw eq_singleton_iff_unique_mem, refine ⟨_, h_uniq⟩,
rw ← h_uniq hne.some hne.some_spec, apply hne.some_spec, },
end
lemma singleton_iff_unique_mem (s : finset α) : (∃ a, s = {a}) ↔ ∃! a, a ∈ s :=
by simp only [eq_singleton_iff_unique_mem, exists_unique]
lemma singleton_subset_set_iff {s : set α} {a : α} :
↑({a} : finset α) ⊆ s ↔ a ∈ s :=
by rw [coe_singleton, set.singleton_subset_iff]
@[simp] lemma singleton_subset_iff {s : finset α} {a : α} :
{a} ⊆ s ↔ a ∈ s :=
singleton_subset_set_iff
@[simp] lemma subset_singleton_iff {s : finset α} {a : α} : s ⊆ {a} ↔ s = ∅ ∨ s = {a} :=
begin
split,
{ intro hs,
apply or.imp_right _ s.eq_empty_or_nonempty,
rintro ⟨t, ht⟩,
apply subset.antisymm hs,
rwa [singleton_subset_iff, ←mem_singleton.1 (hs ht)] },
rintro (rfl | rfl),
{ exact empty_subset _ },
exact subset.refl _,
end
@[simp] lemma ssubset_singleton_iff {s : finset α} {a : α} :
s ⊂ {a} ↔ s = ∅ :=
by rw [←coe_ssubset, coe_singleton, set.ssubset_singleton_iff, coe_eq_empty]
lemma eq_empty_of_ssubset_singleton {s : finset α} {x : α} (hs : s ⊂ {x}) : s = ∅ :=
ssubset_singleton_iff.1 hs
/-! ### cons -/
/-- `cons a s h` is the set `{a} ∪ s` containing `a` and the elements of `s`. It is the same as
`insert a s` when it is defined, but unlike `insert a s` it does not require `decidable_eq α`,
and the union is guaranteed to be disjoint. -/
def cons {α} (a : α) (s : finset α) (h : a ∉ s) : finset α :=
⟨a ::ₘ s.1, multiset.nodup_cons.2 ⟨h, s.2⟩⟩
@[simp] theorem mem_cons {a s h b} : b ∈ @cons α a s h ↔ b = a ∨ b ∈ s :=
by rcases s with ⟨⟨s⟩⟩; apply list.mem_cons_iff
@[simp] theorem cons_val {a : α} {s : finset α} (h : a ∉ s) : (cons a s h).1 = a ::ₘ s.1 := rfl
@[simp] theorem mk_cons {a : α} {s : multiset α} (h : (a ::ₘ s).nodup) :
(⟨a ::ₘ s, h⟩ : finset α) = cons a ⟨s, (multiset.nodup_cons.1 h).2⟩ (multiset.nodup_cons.1 h).1 :=
rfl
@[simp] theorem nonempty_cons {a : α} {s : finset α} (h : a ∉ s) : (cons a s h).nonempty :=
⟨a, mem_cons.2 (or.inl rfl)⟩
@[simp] lemma nonempty_mk_coe : ∀ {l : list α} {hl}, (⟨↑l, hl⟩ : finset α).nonempty ↔ l ≠ []
| [] hl := by simp
| (a::l) hl := by simp [← multiset.cons_coe]
@[simp] lemma coe_cons {a s h} : (@cons α a s h : set α) = insert a s := by { ext, simp }
@[simp] lemma cons_subset_cons {a s hs t ht} :
@cons α a s hs ⊆ cons a t ht ↔ s ⊆ t :=
by rwa [← coe_subset, coe_cons, coe_cons, set.insert_subset_insert_iff, coe_subset]
/-! ### disjoint union -/
/-- `disj_union s t h` is the set such that `a ∈ disj_union s t h` iff `a ∈ s` or `a ∈ t`.
It is the same as `s ∪ t`, but it does not require decidable equality on the type. The hypothesis
ensures that the sets are disjoint. -/
def disj_union {α} (s t : finset α) (h : ∀ a ∈ s, a ∉ t) : finset α :=
⟨s.1 + t.1, multiset.nodup_add.2 ⟨s.2, t.2, h⟩⟩
@[simp] theorem mem_disj_union {α s t h a} :
a ∈ @disj_union α s t h ↔ a ∈ s ∨ a ∈ t :=
by rcases s with ⟨⟨s⟩⟩; rcases t with ⟨⟨t⟩⟩; apply list.mem_append
/-! ### insert -/
section decidable_eq
variables [decidable_eq α]
/-- `insert a s` is the set `{a} ∪ s` containing `a` and the elements of `s`. -/
instance : has_insert α (finset α) := ⟨λ a s, ⟨_, nodup_ndinsert a s.2⟩⟩
theorem insert_def (a : α) (s : finset α) : insert a s = ⟨_, nodup_ndinsert a s.2⟩ := rfl
@[simp] theorem insert_val (a : α) (s : finset α) : (insert a s).1 = ndinsert a s.1 := rfl
theorem insert_val' (a : α) (s : finset α) : (insert a s).1 = erase_dup (a ::ₘ s.1) :=
by rw [erase_dup_cons, erase_dup_eq_self]; refl
theorem insert_val_of_not_mem {a : α} {s : finset α} (h : a ∉ s) : (insert a s).1 = a ::ₘ s.1 :=
by rw [insert_val, ndinsert_of_not_mem h]
@[simp] theorem mem_insert {a b : α} {s : finset α} : a ∈ insert b s ↔ a = b ∨ a ∈ s := mem_ndinsert
theorem mem_insert_self (a : α) (s : finset α) : a ∈ insert a s := mem_ndinsert_self a s.1
theorem mem_insert_of_mem {a b : α} {s : finset α} (h : a ∈ s) : a ∈ insert b s :=
mem_ndinsert_of_mem h
theorem mem_of_mem_insert_of_ne {a b : α} {s : finset α} (h : b ∈ insert a s) : b ≠ a → b ∈ s :=
(mem_insert.1 h).resolve_left
@[simp] theorem cons_eq_insert {α} [decidable_eq α] (a s h) : @cons α a s h = insert a s :=
ext $ λ a, by simp
@[simp, norm_cast] lemma coe_insert (a : α) (s : finset α) :
↑(insert a s) = (insert a s : set α) :=
set.ext $ λ x, by simp only [mem_coe, mem_insert, set.mem_insert_iff]
lemma mem_insert_coe {s : finset α} {x y : α} : x ∈ insert y s ↔ x ∈ insert y (s : set α) :=
by simp
instance : is_lawful_singleton α (finset α) := ⟨λ a, by { ext, simp }⟩
@[simp] theorem insert_eq_of_mem {a : α} {s : finset α} (h : a ∈ s) : insert a s = s :=
eq_of_veq $ ndinsert_of_mem h
@[simp] theorem insert_singleton_self_eq (a : α) : ({a, a} : finset α) = {a} :=
insert_eq_of_mem $ mem_singleton_self _
theorem insert.comm (a b : α) (s : finset α) : insert a (insert b s) = insert b (insert a s) :=
ext $ λ x, by simp only [mem_insert, or.left_comm]
theorem insert_singleton_comm (a b : α) : ({a, b} : finset α) = {b, a} :=
begin
ext,
simp [or.comm]
end
@[simp] theorem insert_idem (a : α) (s : finset α) : insert a (insert a s) = insert a s :=
ext $ λ x, by simp only [mem_insert, or.assoc.symm, or_self]
@[simp] theorem insert_nonempty (a : α) (s : finset α) : (insert a s).nonempty :=
⟨a, mem_insert_self a s⟩
@[simp] theorem insert_ne_empty (a : α) (s : finset α) : insert a s ≠ ∅ :=
(insert_nonempty a s).ne_empty
section
/-!
The universe annotation is required for the following instance, possibly this is a bug in Lean. See
leanprover.zulipchat.com/#narrow/stream/113488-general/topic/strange.20error.20(universe.20issue.3F)
-/
instance {α : Type u} [decidable_eq α] (i : α) (s : finset α) :
nonempty.{u + 1} ((insert i s : finset α) : set α) :=
(finset.coe_nonempty.mpr (s.insert_nonempty i)).to_subtype
end
lemma ne_insert_of_not_mem (s t : finset α) {a : α} (h : a ∉ s) :
s ≠ insert a t :=
by { contrapose! h, simp [h] }
theorem insert_subset {a : α} {s t : finset α} : insert a s ⊆ t ↔ a ∈ t ∧ s ⊆ t :=
by simp only [subset_iff, mem_insert, forall_eq, or_imp_distrib, forall_and_distrib]
theorem subset_insert (a : α) (s : finset α) : s ⊆ insert a s :=
λ b, mem_insert_of_mem
theorem insert_subset_insert (a : α) {s t : finset α} (h : s ⊆ t) : insert a s ⊆ insert a t :=
insert_subset.2 ⟨mem_insert_self _ _, subset.trans h (subset_insert _ _)⟩
lemma ssubset_iff {s t : finset α} : s ⊂ t ↔ (∃a ∉ s, insert a s ⊆ t) :=
by exact_mod_cast @set.ssubset_iff_insert α s t
lemma ssubset_insert {s : finset α} {a : α} (h : a ∉ s) : s ⊂ insert a s :=
ssubset_iff.mpr ⟨a, h, subset.refl _⟩
@[elab_as_eliminator]
lemma cons_induction {α : Type*} {p : finset α → Prop}
(h₁ : p ∅) (h₂ : ∀ ⦃a : α⦄ {s : finset α} (h : a ∉ s), p s → p (cons a s h)) : ∀ s, p s
| ⟨s, nd⟩ := multiset.induction_on s (λ _, h₁) (λ a s IH nd, begin
cases nodup_cons.1 nd with m nd',
rw [← (eq_of_veq _ : cons a (finset.mk s _) m = ⟨a ::ₘ s, nd⟩)],
{ exact h₂ (by exact m) (IH nd') },
{ rw [cons_val] }
end) nd
@[elab_as_eliminator]
lemma cons_induction_on {α : Type*} {p : finset α → Prop} (s : finset α)
(h₁ : p ∅) (h₂ : ∀ ⦃a : α⦄ {s : finset α} (h : a ∉ s), p s → p (cons a s h)) : p s :=
cons_induction h₁ h₂ s
@[elab_as_eliminator]
protected theorem induction {α : Type*} {p : finset α → Prop} [decidable_eq α]
(h₁ : p ∅) (h₂ : ∀ ⦃a : α⦄ {s : finset α}, a ∉ s → p s → p (insert a s)) : ∀ s, p s :=
cons_induction h₁ $ λ a s ha, (s.cons_eq_insert a ha).symm ▸ h₂ ha
/--
To prove a proposition about an arbitrary `finset α`,
it suffices to prove it for the empty `finset`,
and to show that if it holds for some `finset α`,
then it holds for the `finset` obtained by inserting a new element.
-/
@[elab_as_eliminator]
protected theorem induction_on {α : Type*} {p : finset α → Prop} [decidable_eq α]
(s : finset α) (h₁ : p ∅) (h₂ : ∀ ⦃a : α⦄ {s : finset α}, a ∉ s → p s → p (insert a s)) : p s :=
finset.induction h₁ h₂ s
/--
To prove a proposition about `S : finset α`,
it suffices to prove it for the empty `finset`,
and to show that if it holds for some `finset α ⊆ S`,
then it holds for the `finset` obtained by inserting a new element of `S`.
-/
@[elab_as_eliminator]
theorem induction_on' {α : Type*} {p : finset α → Prop} [decidable_eq α]
(S : finset α) (h₁ : p ∅) (h₂ : ∀ {a s}, a ∈ S → s ⊆ S → a ∉ s → p s → p (insert a s)) : p S :=
@finset.induction_on α (λ T, T ⊆ S → p T) _ S (λ _, h₁) (λ a s has hqs hs,
let ⟨hS, sS⟩ := finset.insert_subset.1 hs in h₂ hS sS has (hqs sS)) (finset.subset.refl S)
/-- To prove a proposition about a nonempty `s : finset α`, it suffices to show it holds for all
singletons and that if it holds for `t : finset α`, then it also holds for the `finset` obtained by
inserting an element in `t`. -/
@[elab_as_eliminator]
lemma nonempty.cons_induction {α : Type*} {s : finset α} (hs : s.nonempty) {p : finset α → Prop}
(h₀ : ∀ a, p {a}) (h₁ : ∀ ⦃a⦄ s (h : a ∉ s), p s → p (finset.cons a s h)) :
p s :=
begin
induction s using finset.cons_induction with a t ha h,
{ exact (not_nonempty_empty hs).elim, },
obtain rfl | ht := t.eq_empty_or_nonempty,
{ exact h₀ a },
{ exact h₁ t ha (h ht) }
end
/-- Inserting an element to a finite set is equivalent to the option type. -/
def subtype_insert_equiv_option {t : finset α} {x : α} (h : x ∉ t) :
{i // i ∈ insert x t} ≃ option {i // i ∈ t} :=
begin
refine
{ to_fun := λ y, if h : ↑y = x then none else some ⟨y, (mem_insert.mp y.2).resolve_left h⟩,
inv_fun := λ y, y.elim ⟨x, mem_insert_self _ _⟩ $ λ z, ⟨z, mem_insert_of_mem z.2⟩,
.. },
{ intro y, by_cases h : ↑y = x,
simp only [subtype.ext_iff, h, option.elim, dif_pos, subtype.coe_mk],
simp only [h, option.elim, dif_neg, not_false_iff, subtype.coe_eta, subtype.coe_mk] },
{ rintro (_|y), simp only [option.elim, dif_pos, subtype.coe_mk],
have : ↑y ≠ x, { rintro ⟨⟩, exact h y.2 },
simp only [this, option.elim, subtype.eta, dif_neg, not_false_iff, subtype.coe_eta,
subtype.coe_mk] },
end
/-! ### union -/
/-- `s ∪ t` is the set such that `a ∈ s ∪ t` iff `a ∈ s` or `a ∈ t`. -/
instance : has_union (finset α) := ⟨λ s₁ s₂, ⟨_, nodup_ndunion s₁.1 s₂.2⟩⟩
theorem union_val_nd (s₁ s₂ : finset α) : (s₁ ∪ s₂).1 = ndunion s₁.1 s₂.1 := rfl
@[simp] theorem union_val (s₁ s₂ : finset α) : (s₁ ∪ s₂).1 = s₁.1 ∪ s₂.1 :=
ndunion_eq_union s₁.2
@[simp] theorem mem_union {a : α} {s₁ s₂ : finset α} : a ∈ s₁ ∪ s₂ ↔ a ∈ s₁ ∨ a ∈ s₂ := mem_ndunion
@[simp] theorem disj_union_eq_union {α} [decidable_eq α] (s t h) : @disj_union α s t h = s ∪ t :=
ext $ λ a, by simp
theorem mem_union_left {a : α} {s₁ : finset α} (s₂ : finset α) (h : a ∈ s₁) : a ∈ s₁ ∪ s₂ :=
mem_union.2 $ or.inl h
theorem mem_union_right {a : α} {s₂ : finset α} (s₁ : finset α) (h : a ∈ s₂) : a ∈ s₁ ∪ s₂ :=
mem_union.2 $ or.inr h
theorem forall_mem_union {s₁ s₂ : finset α} {p : α → Prop} :
(∀ ab ∈ (s₁ ∪ s₂), p ab) ↔ (∀ a ∈ s₁, p a) ∧ (∀ b ∈ s₂, p b) :=
⟨λ h, ⟨λ a, h a ∘ mem_union_left _, λ b, h b ∘ mem_union_right _⟩,
λ h ab hab, (mem_union.mp hab).elim (h.1 _) (h.2 _)⟩
theorem not_mem_union {a : α} {s₁ s₂ : finset α} : a ∉ s₁ ∪ s₂ ↔ a ∉ s₁ ∧ a ∉ s₂ :=
by rw [mem_union, not_or_distrib]
@[simp, norm_cast]
lemma coe_union (s₁ s₂ : finset α) : ↑(s₁ ∪ s₂) = (s₁ ∪ s₂ : set α) := set.ext $ λ x, mem_union
theorem union_subset {s₁ s₂ s₃ : finset α} (h₁ : s₁ ⊆ s₃) (h₂ : s₂ ⊆ s₃) : s₁ ∪ s₂ ⊆ s₃ :=
val_le_iff.1 (ndunion_le.2 ⟨h₁, val_le_iff.2 h₂⟩)
theorem subset_union_left (s₁ s₂ : finset α) : s₁ ⊆ s₁ ∪ s₂ := λ x, mem_union_left _
theorem subset_union_right (s₁ s₂ : finset α) : s₂ ⊆ s₁ ∪ s₂ := λ x, mem_union_right _
lemma union_subset_union {s₁ t₁ s₂ t₂ : finset α} (h₁ : s₁ ⊆ t₁) (h₂ : s₂ ⊆ t₂) :
s₁ ∪ s₂ ⊆ t₁ ∪ t₂ :=
by { intros x hx, rw finset.mem_union at hx ⊢, tauto }
theorem union_comm (s₁ s₂ : finset α) : s₁ ∪ s₂ = s₂ ∪ s₁ :=
ext $ λ x, by simp only [mem_union, or_comm]
instance : is_commutative (finset α) (∪) := ⟨union_comm⟩
@[simp] theorem union_assoc (s₁ s₂ s₃ : finset α) : (s₁ ∪ s₂) ∪ s₃ = s₁ ∪ (s₂ ∪ s₃) :=
ext $ λ x, by simp only [mem_union, or_assoc]
instance : is_associative (finset α) (∪) := ⟨union_assoc⟩
@[simp] theorem union_idempotent (s : finset α) : s ∪ s = s :=
ext $ λ _, mem_union.trans $ or_self _
instance : is_idempotent (finset α) (∪) := ⟨union_idempotent⟩
theorem union_subset_left {s₁ s₂ s₃ : finset α} (h : s₁ ∪ s₂ ⊆ s₃) : s₁ ⊆ s₃ :=
subset.trans (subset_union_left _ _) h
theorem union_subset_right {s₁ s₂ s₃ : finset α} (h : s₁ ∪ s₂ ⊆ s₃) : s₂ ⊆ s₃ :=
subset.trans (subset_union_right _ _) h
theorem union_left_comm (s₁ s₂ s₃ : finset α) : s₁ ∪ (s₂ ∪ s₃) = s₂ ∪ (s₁ ∪ s₃) :=
ext $ λ _, by simp only [mem_union, or.left_comm]
theorem union_right_comm (s₁ s₂ s₃ : finset α) : (s₁ ∪ s₂) ∪ s₃ = (s₁ ∪ s₃) ∪ s₂ :=
ext $ λ x, by simp only [mem_union, or_assoc, or_comm (x ∈ s₂)]
theorem union_self (s : finset α) : s ∪ s = s := union_idempotent s
@[simp] theorem union_empty (s : finset α) : s ∪ ∅ = s :=
ext $ λ x, mem_union.trans $ or_false _
@[simp] theorem empty_union (s : finset α) : ∅ ∪ s = s :=
ext $ λ x, mem_union.trans $ false_or _
theorem insert_eq (a : α) (s : finset α) : insert a s = {a} ∪ s := rfl
@[simp] theorem insert_union (a : α) (s t : finset α) : insert a s ∪ t = insert a (s ∪ t) :=
by simp only [insert_eq, union_assoc]
@[simp] theorem union_insert (a : α) (s t : finset α) : s ∪ insert a t = insert a (s ∪ t) :=
by simp only [insert_eq, union_left_comm]
theorem insert_union_distrib (a : α) (s t : finset α) :
insert a (s ∪ t) = insert a s ∪ insert a t :=
by simp only [insert_union, union_insert, insert_idem]
@[simp] lemma union_eq_left_iff_subset {s t : finset α} :
s ∪ t = s ↔ t ⊆ s :=
begin
split,
{ assume h,
have : t ⊆ s ∪ t := subset_union_right _ _,
rwa h at this },
{ assume h,
exact subset.antisymm (union_subset (subset.refl _) h) (subset_union_left _ _) }
end
@[simp] lemma left_eq_union_iff_subset {s t : finset α} :
s = s ∪ t ↔ t ⊆ s :=
by rw [← union_eq_left_iff_subset, eq_comm]
@[simp] lemma union_eq_right_iff_subset {s t : finset α} :
t ∪ s = s ↔ t ⊆ s :=
by rw [union_comm, union_eq_left_iff_subset]
@[simp] lemma right_eq_union_iff_subset {s t : finset α} :
s = t ∪ s ↔ t ⊆ s :=
by rw [← union_eq_right_iff_subset, eq_comm]
/--
To prove a relation on pairs of `finset X`, it suffices to show that it is
* symmetric,
* it holds when one of the `finset`s is empty,
* it holds for pairs of singletons,
* if it holds for `[a, c]` and for `[b, c]`, then it holds for `[a ∪ b, c]`.
-/
lemma induction_on_union (P : finset α → finset α → Prop)
(symm : ∀ {a b}, P a b → P b a)
(empty_right : ∀ {a}, P a ∅)
(singletons : ∀ {a b}, P {a} {b})
(union_of : ∀ {a b c}, P a c → P b c → P (a ∪ b) c) :
∀ a b, P a b :=
begin
intros a b,
refine finset.induction_on b empty_right (λ x s xs hi, symm _),
rw finset.insert_eq,
apply union_of _ (symm hi),
refine finset.induction_on a empty_right (λ a t ta hi, symm _),
rw finset.insert_eq,
exact union_of singletons (symm hi),
end
lemma exists_mem_subset_of_subset_bUnion_of_directed_on {α ι : Type*}
{f : ι → set α} {c : set ι} {a : ι} (hac : a ∈ c) (hc : directed_on (λ i j, f i ⊆ f j) c)
{s : finset α} (hs : (s : set α) ⊆ ⋃ i ∈ c, f i) : ∃ i ∈ c, (s : set α) ⊆ f i :=
begin
classical,
revert hs,
apply s.induction_on,
{ intros,
use [a, hac],
simp },
{ intros b t hbt htc hbtc,
obtain ⟨i : ι , hic : i ∈ c, hti : (t : set α) ⊆ f i⟩ :=
htc (set.subset.trans (t.subset_insert b) hbtc),
obtain ⟨j, hjc, hbj⟩ : ∃ j ∈ c, b ∈ f j,
by simpa [set.mem_bUnion_iff] using hbtc (t.mem_insert_self b),
rcases hc j hjc i hic with ⟨k, hkc, hk, hk'⟩,
use [k, hkc],
rw [coe_insert, set.insert_subset],
exact ⟨hk hbj, trans hti hk'⟩ }
end
/-! ### inter -/
/-- `s ∩ t` is the set such that `a ∈ s ∩ t` iff `a ∈ s` and `a ∈ t`. -/
instance : has_inter (finset α) := ⟨λ s₁ s₂, ⟨_, nodup_ndinter s₂.1 s₁.2⟩⟩
-- TODO: some of these results may have simpler proofs, once there are enough results
-- to obtain the `lattice` instance.
theorem inter_val_nd (s₁ s₂ : finset α) : (s₁ ∩ s₂).1 = ndinter s₁.1 s₂.1 := rfl
@[simp] theorem inter_val (s₁ s₂ : finset α) : (s₁ ∩ s₂).1 = s₁.1 ∩ s₂.1 :=
ndinter_eq_inter s₁.2
@[simp] theorem mem_inter {a : α} {s₁ s₂ : finset α} : a ∈ s₁ ∩ s₂ ↔ a ∈ s₁ ∧ a ∈ s₂ := mem_ndinter
theorem mem_of_mem_inter_left {a : α} {s₁ s₂ : finset α} (h : a ∈ s₁ ∩ s₂) :
a ∈ s₁ := (mem_inter.1 h).1
theorem mem_of_mem_inter_right {a : α} {s₁ s₂ : finset α} (h : a ∈ s₁ ∩ s₂) :
a ∈ s₂ := (mem_inter.1 h).2
theorem mem_inter_of_mem {a : α} {s₁ s₂ : finset α} : a ∈ s₁ → a ∈ s₂ → a ∈ s₁ ∩ s₂ :=
and_imp.1 mem_inter.2
theorem inter_subset_left (s₁ s₂ : finset α) : s₁ ∩ s₂ ⊆ s₁ := λ a, mem_of_mem_inter_left
theorem inter_subset_right (s₁ s₂ : finset α) : s₁ ∩ s₂ ⊆ s₂ := λ a, mem_of_mem_inter_right
theorem subset_inter {s₁ s₂ s₃ : finset α} : s₁ ⊆ s₂ → s₁ ⊆ s₃ → s₁ ⊆ s₂ ∩ s₃ :=
by simp only [subset_iff, mem_inter] {contextual:=tt}; intros; split; trivial
@[simp, norm_cast]
lemma coe_inter (s₁ s₂ : finset α) : ↑(s₁ ∩ s₂) = (s₁ ∩ s₂ : set α) := set.ext $ λ _, mem_inter
@[simp] theorem union_inter_cancel_left {s t : finset α} : (s ∪ t) ∩ s = s :=
by rw [← coe_inj, coe_inter, coe_union, set.union_inter_cancel_left]
@[simp] theorem union_inter_cancel_right {s t : finset α} : (s ∪ t) ∩ t = t :=
by rw [← coe_inj, coe_inter, coe_union, set.union_inter_cancel_right]
theorem inter_comm (s₁ s₂ : finset α) : s₁ ∩ s₂ = s₂ ∩ s₁ :=
ext $ λ _, by simp only [mem_inter, and_comm]
@[simp] theorem inter_assoc (s₁ s₂ s₃ : finset α) : (s₁ ∩ s₂) ∩ s₃ = s₁ ∩ (s₂ ∩ s₃) :=
ext $ λ _, by simp only [mem_inter, and_assoc]
theorem inter_left_comm (s₁ s₂ s₃ : finset α) : s₁ ∩ (s₂ ∩ s₃) = s₂ ∩ (s₁ ∩ s₃) :=
ext $ λ _, by simp only [mem_inter, and.left_comm]
theorem inter_right_comm (s₁ s₂ s₃ : finset α) : (s₁ ∩ s₂) ∩ s₃ = (s₁ ∩ s₃) ∩ s₂ :=
ext $ λ _, by simp only [mem_inter, and.right_comm]
@[simp] theorem inter_self (s : finset α) : s ∩ s = s :=
ext $ λ _, mem_inter.trans $ and_self _
@[simp] theorem inter_empty (s : finset α) : s ∩ ∅ = ∅ :=
ext $ λ _, mem_inter.trans $ and_false _
@[simp] theorem empty_inter (s : finset α) : ∅ ∩ s = ∅ :=
ext $ λ _, mem_inter.trans $ false_and _
@[simp] lemma inter_union_self (s t : finset α) : s ∩ (t ∪ s) = s :=
by rw [inter_comm, union_inter_cancel_right]
@[simp] theorem insert_inter_of_mem {s₁ s₂ : finset α} {a : α} (h : a ∈ s₂) :
insert a s₁ ∩ s₂ = insert a (s₁ ∩ s₂) :=
ext $ λ x, have x = a ∨ x ∈ s₂ ↔ x ∈ s₂, from or_iff_right_of_imp $ by rintro rfl; exact h,
by simp only [mem_inter, mem_insert, or_and_distrib_left, this]
@[simp] theorem inter_insert_of_mem {s₁ s₂ : finset α} {a : α} (h : a ∈ s₁) :
s₁ ∩ insert a s₂ = insert a (s₁ ∩ s₂) :=
by rw [inter_comm, insert_inter_of_mem h, inter_comm]
@[simp] theorem insert_inter_of_not_mem {s₁ s₂ : finset α} {a : α} (h : a ∉ s₂) :
insert a s₁ ∩ s₂ = s₁ ∩ s₂ :=
ext $ λ x, have ¬ (x = a ∧ x ∈ s₂), by rintro ⟨rfl, H⟩; exact h H,
by simp only [mem_inter, mem_insert, or_and_distrib_right, this, false_or]
@[simp] theorem inter_insert_of_not_mem {s₁ s₂ : finset α} {a : α} (h : a ∉ s₁) :
s₁ ∩ insert a s₂ = s₁ ∩ s₂ :=
by rw [inter_comm, insert_inter_of_not_mem h, inter_comm]
@[simp] theorem singleton_inter_of_mem {a : α} {s : finset α} (H : a ∈ s) : {a} ∩ s = {a} :=
show insert a ∅ ∩ s = insert a ∅, by rw [insert_inter_of_mem H, empty_inter]
@[simp] theorem singleton_inter_of_not_mem {a : α} {s : finset α} (H : a ∉ s) : {a} ∩ s = ∅ :=
eq_empty_of_forall_not_mem $ by simp only [mem_inter, mem_singleton]; rintro x ⟨rfl, h⟩; exact H h
@[simp] theorem inter_singleton_of_mem {a : α} {s : finset α} (h : a ∈ s) : s ∩ {a} = {a} :=
by rw [inter_comm, singleton_inter_of_mem h]
@[simp] theorem inter_singleton_of_not_mem {a : α} {s : finset α} (h : a ∉ s) : s ∩ {a} = ∅ :=
by rw [inter_comm, singleton_inter_of_not_mem h]
@[mono]
lemma inter_subset_inter {x y s t : finset α} (h : x ⊆ y) (h' : s ⊆ t) : x ∩ s ⊆ y ∩ t :=
begin
intros a a_in,
rw finset.mem_inter at a_in ⊢,
exact ⟨h a_in.1, h' a_in.2⟩
end
lemma inter_subset_inter_right {x y s : finset α} (h : x ⊆ y) : x ∩ s ⊆ y ∩ s :=
finset.inter_subset_inter h (finset.subset.refl _)
lemma inter_subset_inter_left {x y s : finset α} (h : x ⊆ y) : s ∩ x ⊆ s ∩ y :=
finset.inter_subset_inter (finset.subset.refl _) h
/-! ### lattice laws -/
instance : lattice (finset α) :=
{ sup := (∪),
sup_le := assume a b c, union_subset,
le_sup_left := subset_union_left,
le_sup_right := subset_union_right,
inf := (∩),
le_inf := assume a b c, subset_inter,
inf_le_left := inter_subset_left,
inf_le_right := inter_subset_right,
..finset.partial_order }
@[simp] theorem sup_eq_union : ((⊔) : finset α → finset α → finset α) = (∪) := rfl
@[simp] theorem inf_eq_inter : ((⊓) : finset α → finset α → finset α) = (∩) := rfl
instance {α : Type u} : order_bot (finset α) :=
{ bot := ∅, bot_le := empty_subset }
instance : semilattice_inf_bot (finset α) :=
{ ..finset.order_bot, ..finset.lattice }
@[simp] lemma bot_eq_empty {α : Type u} : (⊥ : finset α) = ∅ := rfl
instance : semilattice_sup_bot (finset α) :=
{ ..finset.semilattice_inf_bot, ..finset.lattice }
instance : distrib_lattice (finset α) :=
{ le_sup_inf := assume a b c, show (a ∪ b) ∩ (a ∪ c) ⊆ a ∪ b ∩ c,
by simp only [subset_iff, mem_inter, mem_union, and_imp, or_imp_distrib] {contextual:=tt};
simp only [true_or, imp_true_iff, true_and, or_true],
..finset.lattice }
@[simp] theorem union_left_idem (s t : finset α) : s ∪ (s ∪ t) = s ∪ t := sup_left_idem
@[simp] theorem union_right_idem (s t : finset α) : s ∪ t ∪ t = s ∪ t := sup_right_idem
@[simp] theorem inter_left_idem (s t : finset α) : s ∩ (s ∩ t) = s ∩ t := inf_left_idem
@[simp] theorem inter_right_idem (s t : finset α) : s ∩ t ∩ t = s ∩ t := inf_right_idem
theorem inter_distrib_left (s t u : finset α) : s ∩ (t ∪ u) = (s ∩ t) ∪ (s ∩ u) := inf_sup_left
theorem inter_distrib_right (s t u : finset α) : (s ∪ t) ∩ u = (s ∩ u) ∪ (t ∩ u) := inf_sup_right
theorem union_distrib_left (s t u : finset α) : s ∪ (t ∩ u) = (s ∪ t) ∩ (s ∪ u) := sup_inf_left
theorem union_distrib_right (s t u : finset α) : (s ∩ t) ∪ u = (s ∪ u) ∩ (t ∪ u) := sup_inf_right
lemma union_eq_empty_iff (A B : finset α) : A ∪ B = ∅ ↔ A = ∅ ∧ B = ∅ := sup_eq_bot_iff
lemma union_subset_iff {s₁ s₂ s₃ : finset α} :
s₁ ∪ s₂ ⊆ s₃ ↔ s₁ ⊆ s₃ ∧ s₂ ⊆ s₃ :=
(sup_le_iff : s₁ ⊔ s₂ ≤ s₃ ↔ s₁ ≤ s₃ ∧ s₂ ≤ s₃)
lemma subset_inter_iff {s₁ s₂ s₃ : finset α} :
s₁ ⊆ s₂ ∩ s₃ ↔ s₁ ⊆ s₂ ∧ s₁ ⊆ s₃ :=
(le_inf_iff : s₁ ≤ s₂ ⊓ s₃ ↔ s₁ ≤ s₂ ∧ s₁ ≤ s₃)
theorem inter_eq_left_iff_subset (s t : finset α) :
s ∩ t = s ↔ s ⊆ t :=
(inf_eq_left : s ⊓ t = s ↔ s ≤ t)
theorem inter_eq_right_iff_subset (s t : finset α) :
t ∩ s = s ↔ s ⊆ t :=
(inf_eq_right : t ⊓ s = s ↔ s ≤ t)
/-! ### erase -/
/-- `erase s a` is the set `s - {a}`, that is, the elements of `s` which are
not equal to `a`. -/
def erase (s : finset α) (a : α) : finset α := ⟨_, nodup_erase_of_nodup a s.2⟩
@[simp] theorem erase_val (s : finset α) (a : α) : (erase s a).1 = s.1.erase a := rfl
@[simp] theorem mem_erase {a b : α} {s : finset α} : a ∈ erase s b ↔ a ≠ b ∧ a ∈ s :=
mem_erase_iff_of_nodup s.2
theorem not_mem_erase (a : α) (s : finset α) : a ∉ erase s a := mem_erase_of_nodup s.2
-- While this can be solved by `simp`, this lemma is eligible for `dsimp`
@[nolint simp_nf, simp] theorem erase_empty (a : α) : erase ∅ a = ∅ := rfl
@[simp] lemma erase_singleton (a : α) : ({a} : finset α).erase a = ∅ :=
begin
ext x,
rw [mem_erase, mem_singleton, not_and_self],
refl,
end
theorem ne_of_mem_erase {a b : α} {s : finset α} : b ∈ erase s a → b ≠ a :=
by simp only [mem_erase]; exact and.left
theorem mem_of_mem_erase {a b : α} {s : finset α} : b ∈ erase s a → b ∈ s := mem_of_mem_erase
theorem mem_erase_of_ne_of_mem {a b : α} {s : finset α} : a ≠ b → a ∈ s → a ∈ erase s b :=
by simp only [mem_erase]; exact and.intro
/-- An element of `s` that is not an element of `erase s a` must be
`a`. -/
lemma eq_of_mem_of_not_mem_erase {a b : α} {s : finset α} (hs : b ∈ s)
(hsa : b ∉ s.erase a) : b = a :=
begin
rw [mem_erase, not_and] at hsa,
exact not_imp_not.mp hsa hs
end
theorem erase_insert {a : α} {s : finset α} (h : a ∉ s) : erase (insert a s) a = s :=
ext $ assume x, by simp only [mem_erase, mem_insert, and_or_distrib_left, not_and_self, false_or];
apply and_iff_right_of_imp; rintro H rfl; exact h H
theorem insert_erase {a : α} {s : finset α} (h : a ∈ s) : insert a (erase s a) = s :=
ext $ assume x, by simp only [mem_insert, mem_erase, or_and_distrib_left, dec_em, true_and];
apply or_iff_right_of_imp; rintro rfl; exact h
theorem erase_subset_erase (a : α) {s t : finset α} (h : s ⊆ t) : erase s a ⊆ erase t a :=
val_le_iff.1 $ erase_le_erase _ $ val_le_iff.2 h
theorem erase_subset (a : α) (s : finset α) : erase s a ⊆ s := erase_subset _ _
@[simp, norm_cast] lemma coe_erase (a : α) (s : finset α) : ↑(erase s a) = (s \ {a} : set α) :=
set.ext $ λ _, mem_erase.trans $ by rw [and_comm, set.mem_diff, set.mem_singleton_iff]; refl
lemma erase_ssubset {a : α} {s : finset α} (h : a ∈ s) : s.erase a ⊂ s :=
calc s.erase a ⊂ insert a (s.erase a) : ssubset_insert $ not_mem_erase _ _
... = _ : insert_erase h
@[simp]
theorem erase_eq_of_not_mem {a : α} {s : finset α} (h : a ∉ s) : erase s a = s :=
eq_of_veq $ erase_of_not_mem h
theorem subset_insert_iff {a : α} {s t : finset α} : s ⊆ insert a t ↔ erase s a ⊆ t :=
by simp only [subset_iff, or_iff_not_imp_left, mem_erase, mem_insert, and_imp];
exact forall_congr (λ x, forall_swap)
theorem erase_insert_subset (a : α) (s : finset α) : erase (insert a s) a ⊆ s :=
subset_insert_iff.1 $ subset.refl _
theorem insert_erase_subset (a : α) (s : finset α) : s ⊆ insert a (erase s a) :=
subset_insert_iff.2 $ subset.refl _
lemma erase_inj {x y : α} (s : finset α) (hx : x ∈ s) :
s.erase x = s.erase y ↔ x = y :=
begin
refine ⟨λ h, _, congr_arg _⟩,
rw eq_of_mem_of_not_mem_erase hx,
rw ←h,
simp,
end
lemma erase_inj_on (s : finset α) : set.inj_on s.erase s :=
λ _ _ _ _, (erase_inj s ‹_›).mp
/-! ### sdiff -/
/-- `s \ t` is the set consisting of the elements of `s` that are not in `t`. -/
instance : has_sdiff (finset α) :=
⟨λs₁ s₂, ⟨s₁.1 - s₂.1, nodup_of_le tsub_le_self s₁.2⟩⟩
@[simp] lemma sdiff_val (s₁ s₂ : finset α) : (s₁ \ s₂).val = s₁.val - s₂.val := rfl
@[simp] theorem mem_sdiff {a : α} {s₁ s₂ : finset α} :
a ∈ s₁ \ s₂ ↔ a ∈ s₁ ∧ a ∉ s₂ := mem_sub_of_nodup s₁.2
@[simp] theorem inter_sdiff_self (s₁ s₂ : finset α) : s₁ ∩ (s₂ \ s₁) = ∅ :=
eq_empty_of_forall_not_mem $
by simp only [mem_inter, mem_sdiff]; rintro x ⟨h, _, hn⟩; exact hn h
instance : generalized_boolean_algebra (finset α) :=
{ sup_inf_sdiff := λ x y, by { simp only [ext_iff, mem_union, mem_sdiff, inf_eq_inter, sup_eq_union,
mem_inter], tauto },
inf_inf_sdiff := λ x y, by { simp only [ext_iff, inter_sdiff_self, inter_empty, inter_assoc,
false_iff, inf_eq_inter, not_mem_empty], tauto },
..finset.has_sdiff,
..finset.distrib_lattice,
..finset.semilattice_inf_bot }
lemma not_mem_sdiff_of_mem_right {a : α} {s t : finset α} (h : a ∈ t) : a ∉ s \ t :=
by simp only [mem_sdiff, h, not_true, not_false_iff, and_false]
theorem union_sdiff_of_subset {s₁ s₂ : finset α} (h : s₁ ⊆ s₂) : s₁ ∪ (s₂ \ s₁) = s₂ :=
sup_sdiff_cancel_right h
theorem sdiff_union_of_subset {s₁ s₂ : finset α} (h : s₁ ⊆ s₂) : (s₂ \ s₁) ∪ s₁ = s₂ :=
(union_comm _ _).trans (union_sdiff_of_subset h)
theorem inter_sdiff (s t u : finset α) : s ∩ (t \ u) = s ∩ t \ u :=
by { ext x, simp [and_assoc] }
@[simp] theorem sdiff_inter_self (s₁ s₂ : finset α) : (s₂ \ s₁) ∩ s₁ = ∅ :=
inf_sdiff_self_left
@[simp] theorem sdiff_self (s₁ : finset α) : s₁ \ s₁ = ∅ :=
sdiff_self
theorem sdiff_inter_distrib_right (s₁ s₂ s₃ : finset α) : s₁ \ (s₂ ∩ s₃) = (s₁ \ s₂) ∪ (s₁ \ s₃) :=
sdiff_inf
@[simp] theorem sdiff_inter_self_left (s₁ s₂ : finset α) : s₁ \ (s₁ ∩ s₂) = s₁ \ s₂ :=
sdiff_inf_self_left
@[simp] theorem sdiff_inter_self_right (s₁ s₂ : finset α) : s₁ \ (s₂ ∩ s₁) = s₁ \ s₂ :=
sdiff_inf_self_right
@[simp] theorem sdiff_empty {s₁ : finset α} : s₁ \ ∅ = s₁ :=
sdiff_bot
@[mono]
theorem sdiff_subset_sdiff {s₁ s₂ t₁ t₂ : finset α} (h₁ : t₁ ⊆ t₂) (h₂ : s₂ ⊆ s₁) :
t₁ \ s₁ ⊆ t₂ \ s₂ :=
sdiff_le_sdiff ‹t₁ ≤ t₂› ‹s₂ ≤ s₁›
@[simp, norm_cast] lemma coe_sdiff (s₁ s₂ : finset α) : ↑(s₁ \ s₂) = (s₁ \ s₂ : set α) :=
set.ext $ λ _, mem_sdiff
@[simp] theorem union_sdiff_self_eq_union {s t : finset α} : s ∪ (t \ s) = s ∪ t :=
sup_sdiff_self_right
@[simp] theorem sdiff_union_self_eq_union {s t : finset α} : (s \ t) ∪ t = s ∪ t :=
sup_sdiff_self_left
lemma union_sdiff_symm {s t : finset α} : s ∪ (t \ s) = t ∪ (s \ t) :=
sup_sdiff_symm
lemma sdiff_union_inter (s t : finset α) : (s \ t) ∪ (s ∩ t) = s :=
by { rw union_comm, exact sup_inf_sdiff _ _ }
@[simp] lemma sdiff_idem (s t : finset α) : s \ t \ t = s \ t :=
sdiff_idem
lemma sdiff_eq_empty_iff_subset {s t : finset α} : s \ t = ∅ ↔ s ⊆ t :=
sdiff_eq_bot_iff
@[simp] lemma empty_sdiff (s : finset α) : ∅ \ s = ∅ :=
bot_sdiff
lemma insert_sdiff_of_not_mem (s : finset α) {t : finset α} {x : α} (h : x ∉ t) :
(insert x s) \ t = insert x (s \ t) :=
begin
rw [← coe_inj, coe_insert, coe_sdiff, coe_sdiff, coe_insert],
exact set.insert_diff_of_not_mem s h
end
lemma insert_sdiff_of_mem (s : finset α) {t : finset α} {x : α} (h : x ∈ t) :
(insert x s) \ t = s \ t :=
begin
rw [← coe_inj, coe_sdiff, coe_sdiff, coe_insert],
exact set.insert_diff_of_mem s h
end
@[simp] lemma insert_sdiff_insert (s t : finset α) (x : α) :
(insert x s) \ (insert x t) = s \ insert x t :=
insert_sdiff_of_mem _ (mem_insert_self _ _)
lemma sdiff_insert_of_not_mem {s : finset α} {x : α} (h : x ∉ s) (t : finset α) :
s \ (insert x t) = s \ t :=
begin
refine subset.antisymm (sdiff_subset_sdiff (subset.refl _) (subset_insert _ _)) (λ y hy, _),
simp only [mem_sdiff, mem_insert, not_or_distrib] at hy ⊢,
exact ⟨hy.1, λ hxy, h $ hxy ▸ hy.1, hy.2⟩
end
@[simp] lemma sdiff_subset (s t : finset α) : s \ t ⊆ s :=
show s \ t ≤ s, from sdiff_le
lemma sdiff_ssubset {s t : finset α} (h : t ⊆ s) (ht : t.nonempty) :
s \ t ⊂ s :=
sdiff_lt (le_iff_subset.2 h) ht.ne_empty
lemma union_sdiff_distrib (s₁ s₂ t : finset α) : (s₁ ∪ s₂) \ t = s₁ \ t ∪ s₂ \ t :=
sup_sdiff
lemma sdiff_union_distrib (s t₁ t₂ : finset α) : s \ (t₁ ∪ t₂) = (s \ t₁) ∩ (s \ t₂) :=
sdiff_sup
lemma union_sdiff_self (s t : finset α) : (s ∪ t) \ t = s \ t :=
sup_sdiff_right_self
lemma sdiff_singleton_eq_erase (a : α) (s : finset α) : s \ singleton a = erase s a :=
by { ext, rw [mem_erase, mem_sdiff, mem_singleton], tauto }
@[simp] lemma sdiff_singleton_not_mem_eq_self (s : finset α) {a : α} (ha : a ∉ s) : s \ {a} = s :=
by simp only [sdiff_singleton_eq_erase, ha, erase_eq_of_not_mem, not_false_iff]
lemma sdiff_sdiff_self_left (s t : finset α) : s \ (s \ t) = s ∩ t :=
sdiff_sdiff_right_self
lemma sdiff_eq_sdiff_iff_inter_eq_inter {s t₁ t₂ : finset α} : s \ t₁ = s \ t₂ ↔ s ∩ t₁ = s ∩ t₂ :=
sdiff_eq_sdiff_iff_inf_eq_inf
lemma union_eq_sdiff_union_sdiff_union_inter (s t : finset α) :
s ∪ t = (s \ t) ∪ (t \ s) ∪ (s ∩ t) :=
sup_eq_sdiff_sup_sdiff_sup_inf
end decidable_eq
/-! ### attach -/
/-- `attach s` takes the elements of `s` and forms a new set of elements of the subtype
`{x // x ∈ s}`. -/
def attach (s : finset α) : finset {x // x ∈ s} := ⟨attach s.1, nodup_attach.2 s.2⟩
theorem sizeof_lt_sizeof_of_mem [has_sizeof α] {x : α} {s : finset α} (hx : x ∈ s) :
sizeof x < sizeof s := by
{ cases s, dsimp [sizeof, has_sizeof.sizeof, finset.sizeof],
apply lt_add_left, exact multiset.sizeof_lt_sizeof_of_mem hx }
@[simp] theorem attach_val (s : finset α) : s.attach.1 = s.1.attach := rfl
@[simp] theorem mem_attach (s : finset α) : ∀ x, x ∈ s.attach := mem_attach _
@[simp] theorem attach_empty : attach (∅ : finset α) = ∅ := rfl
@[simp] lemma attach_nonempty_iff (s : finset α) : s.attach.nonempty ↔ s.nonempty :=
by simp [finset.nonempty]
@[simp] lemma attach_eq_empty_iff (s : finset α) : s.attach = ∅ ↔ s = ∅ :=
by simpa [eq_empty_iff_forall_not_mem]
/-! ### piecewise -/
section piecewise
/-- `s.piecewise f g` is the function equal to `f` on the finset `s`, and to `g` on its
complement. -/
def piecewise {α : Type*} {δ : α → Sort*} (s : finset α) (f g : Πi, δ i) [∀j, decidable (j ∈ s)] :
Πi, δ i :=
λi, if i ∈ s then f i else g i
variables {δ : α → Sort*} (s : finset α) (f g : Πi, δ i)
@[simp] lemma piecewise_insert_self [decidable_eq α] {j : α} [∀i, decidable (i ∈ insert j s)] :
(insert j s).piecewise f g j = f j :=
by simp [piecewise]
@[simp] lemma piecewise_empty [∀i : α, decidable (i ∈ (∅ : finset α))] : piecewise ∅ f g = g :=
by { ext i, simp [piecewise] }
variable [∀j, decidable (j ∈ s)]
@[norm_cast] lemma piecewise_coe [∀j, decidable (j ∈ (s : set α))] :
(s : set α).piecewise f g = s.piecewise f g :=
by { ext, congr }
@[simp, priority 980]
lemma piecewise_eq_of_mem {i : α} (hi : i ∈ s) : s.piecewise f g i = f i :=
by simp [piecewise, hi]
@[simp, priority 980]
lemma piecewise_eq_of_not_mem {i : α} (hi : i ∉ s) : s.piecewise f g i = g i :=
by simp [piecewise, hi]
lemma piecewise_congr {f f' g g' : Π i, δ i} (hf : ∀ i ∈ s, f i = f' i) (hg : ∀ i ∉ s, g i = g' i) :
s.piecewise f g = s.piecewise f' g' :=
funext $ λ i, if_ctx_congr iff.rfl (hf i) (hg i)
@[simp, priority 990]
lemma piecewise_insert_of_ne [decidable_eq α] {i j : α} [∀i, decidable (i ∈ insert j s)]
(h : i ≠ j) : (insert j s).piecewise f g i = s.piecewise f g i :=
by simp [piecewise, h]
lemma piecewise_insert [decidable_eq α] (j : α) [∀i, decidable (i ∈ insert j s)] :
(insert j s).piecewise f g = update (s.piecewise f g) j (f j) :=
begin
classical,
rw [← piecewise_coe, ← piecewise_coe, ← set.piecewise_insert, ← coe_insert j s],
congr
end
lemma piecewise_cases {i} (p : δ i → Prop) (hf : p (f i)) (hg : p (g i)) : p (s.piecewise f g i) :=
by by_cases hi : i ∈ s; simpa [hi]
lemma piecewise_mem_set_pi {δ : α → Type*} {t : set α} {t' : Π i, set (δ i)}
{f g} (hf : f ∈ set.pi t t') (hg : g ∈ set.pi t t') : s.piecewise f g ∈ set.pi t t' :=
by { classical, rw ← piecewise_coe, exact set.piecewise_mem_pi ↑s hf hg }
lemma piecewise_singleton [decidable_eq α] (i : α) :
piecewise {i} f g = update g i (f i) :=
by rw [← insert_emptyc_eq, piecewise_insert, piecewise_empty]
lemma piecewise_piecewise_of_subset_left {s t : finset α} [Π i, decidable (i ∈ s)]
[Π i, decidable (i ∈ t)] (h : s ⊆ t) (f₁ f₂ g : Π a, δ a) :
s.piecewise (t.piecewise f₁ f₂) g = s.piecewise f₁ g :=
s.piecewise_congr (λ i hi, piecewise_eq_of_mem _ _ _ (h hi)) (λ _ _, rfl)
@[simp] lemma piecewise_idem_left (f₁ f₂ g : Π a, δ a) :
s.piecewise (s.piecewise f₁ f₂) g = s.piecewise f₁ g :=
piecewise_piecewise_of_subset_left (subset.refl _) _ _ _
lemma piecewise_piecewise_of_subset_right {s t : finset α} [Π i, decidable (i ∈ s)]
[Π i, decidable (i ∈ t)] (h : t ⊆ s) (f g₁ g₂ : Π a, δ a) :
s.piecewise f (t.piecewise g₁ g₂) = s.piecewise f g₂ :=
s.piecewise_congr (λ _ _, rfl) (λ i hi, t.piecewise_eq_of_not_mem _ _ (mt (@h _) hi))
@[simp] lemma piecewise_idem_right (f g₁ g₂ : Π a, δ a) :
s.piecewise f (s.piecewise g₁ g₂) = s.piecewise f g₂ :=
piecewise_piecewise_of_subset_right (subset.refl _) f g₁ g₂
lemma update_eq_piecewise {β : Type*} [decidable_eq α] (f : α → β) (i : α) (v : β) :
update f i v = piecewise (singleton i) (λj, v) f :=
(piecewise_singleton _ _ _).symm
lemma update_piecewise [decidable_eq α] (i : α) (v : δ i) :
update (s.piecewise f g) i v = s.piecewise (update f i v) (update g i v) :=
begin
ext j,
rcases em (j = i) with (rfl|hj); by_cases hs : j ∈ s; simp *
end
lemma update_piecewise_of_mem [decidable_eq α] {i : α} (hi : i ∈ s) (v : δ i) :
update (s.piecewise f g) i v = s.piecewise (update f i v) g :=
begin
rw update_piecewise,
refine s.piecewise_congr (λ _ _, rfl) (λ j hj, update_noteq _ _ _),
exact λ h, hj (h.symm ▸ hi)
end
lemma update_piecewise_of_not_mem [decidable_eq α] {i : α} (hi : i ∉ s) (v : δ i) :
update (s.piecewise f g) i v = s.piecewise f (update g i v) :=
begin
rw update_piecewise,
refine s.piecewise_congr (λ j hj, update_noteq _ _ _) (λ _ _, rfl),
exact λ h, hi (h ▸ hj)
end
lemma piecewise_le_of_le_of_le {δ : α → Type*} [Π i, preorder (δ i)] {f g h : Π i, δ i}
(Hf : f ≤ h) (Hg : g ≤ h) : s.piecewise f g ≤ h :=
λ x, piecewise_cases s f g (≤ h x) (Hf x) (Hg x)
lemma le_piecewise_of_le_of_le {δ : α → Type*} [Π i, preorder (δ i)] {f g h : Π i, δ i}
(Hf : h ≤ f) (Hg : h ≤ g) : h ≤ s.piecewise f g :=
λ x, piecewise_cases s f g (λ y, h x ≤ y) (Hf x) (Hg x)
lemma piecewise_le_piecewise' {δ : α → Type*} [Π i, preorder (δ i)] {f g f' g' : Π i, δ i}
(Hf : ∀ x ∈ s, f x ≤ f' x) (Hg : ∀ x ∉ s, g x ≤ g' x) : s.piecewise f g ≤ s.piecewise f' g' :=
λ x, by { by_cases hx : x ∈ s; simp [hx, *] }
lemma piecewise_le_piecewise {δ : α → Type*} [Π i, preorder (δ i)] {f g f' g' : Π i, δ i}
(Hf : f ≤ f') (Hg : g ≤ g') : s.piecewise f g ≤ s.piecewise f' g' :=
s.piecewise_le_piecewise' (λ x _, Hf x) (λ x _, Hg x)
lemma piecewise_mem_Icc_of_mem_of_mem {δ : α → Type*} [Π i, preorder (δ i)] {f f₁ g g₁ : Π i, δ i}
(hf : f ∈ set.Icc f₁ g₁) (hg : g ∈ set.Icc f₁ g₁) :
s.piecewise f g ∈ set.Icc f₁ g₁ :=
⟨le_piecewise_of_le_of_le _ hf.1 hg.1, piecewise_le_of_le_of_le _ hf.2 hg.2⟩
lemma piecewise_mem_Icc {δ : α → Type*} [Π i, preorder (δ i)] {f g : Π i, δ i} (h : f ≤ g) :
s.piecewise f g ∈ set.Icc f g :=
piecewise_mem_Icc_of_mem_of_mem _ (set.left_mem_Icc.2 h) (set.right_mem_Icc.2 h)
lemma piecewise_mem_Icc' {δ : α → Type*} [Π i, preorder (δ i)] {f g : Π i, δ i} (h : g ≤ f) :
s.piecewise f g ∈ set.Icc g f :=
piecewise_mem_Icc_of_mem_of_mem _ (set.right_mem_Icc.2 h) (set.left_mem_Icc.2 h)
end piecewise
section decidable_pi_exists
variables {s : finset α}
instance decidable_dforall_finset {p : Πa∈s, Prop} [hp : ∀a (h : a ∈ s), decidable (p a h)] :
decidable (∀a (h : a ∈ s), p a h) :=
multiset.decidable_dforall_multiset
/-- decidable equality for functions whose domain is bounded by finsets -/
instance decidable_eq_pi_finset {β : α → Type*} [h : ∀a, decidable_eq (β a)] :
decidable_eq (Πa∈s, β a) :=
multiset.decidable_eq_pi_multiset
instance decidable_dexists_finset {p : Πa∈s, Prop} [hp : ∀a (h : a ∈ s), decidable (p a h)] :
decidable (∃a (h : a ∈ s), p a h) :=
multiset.decidable_dexists_multiset
end decidable_pi_exists
/-! ### filter -/
section filter
variables (p q : α → Prop) [decidable_pred p] [decidable_pred q]
/-- `filter p s` is the set of elements of `s` that satisfy `p`. -/
def filter (s : finset α) : finset α :=
⟨_, nodup_filter p s.2⟩
@[simp] theorem filter_val (s : finset α) : (filter p s).1 = s.1.filter p := rfl
@[simp] theorem filter_subset (s : finset α) : s.filter p ⊆ s := filter_subset _ _
variable {p}
@[simp] theorem mem_filter {s : finset α} {a : α} : a ∈ s.filter p ↔ a ∈ s ∧ p a := mem_filter
theorem filter_ssubset {s : finset α} : s.filter p ⊂ s ↔ ∃ x ∈ s, ¬ p x :=
⟨λ h, let ⟨x, hs, hp⟩ := set.exists_of_ssubset h in ⟨x, hs, mt (λ hp, mem_filter.2 ⟨hs, hp⟩) hp⟩,
λ ⟨x, hs, hp⟩, ⟨s.filter_subset _, λ h, hp (mem_filter.1 (h hs)).2⟩⟩
variable (p)
theorem filter_filter (s : finset α) : (s.filter p).filter q = s.filter (λa, p a ∧ q a) :=
ext $ assume a, by simp only [mem_filter, and_comm, and.left_comm]
lemma filter_true {s : finset α} [h : decidable_pred (λ _, true)] :
@finset.filter α (λ _, true) h s = s :=
by ext; simp
@[simp] theorem filter_false {h} (s : finset α) : @filter α (λa, false) h s = ∅ :=
ext $ assume a, by simp only [mem_filter, and_false]; refl
variables {p q}
/-- If all elements of a `finset` satisfy the predicate `p`, `s.filter p` is `s`. -/
@[simp] lemma filter_true_of_mem {s : finset α} (h : ∀ x ∈ s, p x) : s.filter p = s :=
ext $ λ x, ⟨λ h, (mem_filter.1 h).1, λ hx, mem_filter.2 ⟨hx, h x hx⟩⟩
/-- If all elements of a `finset` fail to satisfy the predicate `p`, `s.filter p` is `∅`. -/
lemma filter_false_of_mem {s : finset α} (h : ∀ x ∈ s, ¬ p x) : s.filter p = ∅ :=
eq_empty_of_forall_not_mem (by simpa)
lemma filter_congr {s : finset α} (H : ∀ x ∈ s, p x ↔ q x) : filter p s = filter q s :=
eq_of_veq $ filter_congr H
variables (p q)
lemma filter_empty : filter p ∅ = ∅ := subset_empty.1 $ filter_subset _ _
lemma filter_subset_filter {s t : finset α} (h : s ⊆ t) : s.filter p ⊆ t.filter p :=
assume a ha, mem_filter.2 ⟨h (mem_filter.1 ha).1, (mem_filter.1 ha).2⟩
lemma monotone_filter_left (p : α → Prop) [decidable_pred p] :
monotone (filter p) :=
λ _ _, filter_subset_filter p
lemma monotone_filter_right (s : finset α) ⦃p q : α → Prop⦄
[decidable_pred p] [decidable_pred q] (h : p ≤ q) :
s.filter p ≤ s.filter q :=
multiset.subset_of_le (multiset.monotone_filter_right s.val h)
@[simp, norm_cast] lemma coe_filter (s : finset α) : ↑(s.filter p) = ({x ∈ ↑s | p x} : set α) :=
set.ext $ λ _, mem_filter
theorem filter_singleton (a : α) : filter p (singleton a) = if p a then singleton a else ∅ :=
by { classical, ext x, simp, split_ifs with h; by_cases h' : x = a; simp [h, h'] }
variable [decidable_eq α]
theorem filter_union (s₁ s₂ : finset α) : (s₁ ∪ s₂).filter p = s₁.filter p ∪ s₂.filter p :=
ext $ λ _, by simp only [mem_filter, mem_union, or_and_distrib_right]
theorem filter_union_right (s : finset α) : s.filter p ∪ s.filter q = s.filter (λx, p x ∨ q x) :=
ext $ λ x, by simp only [mem_filter, mem_union, and_or_distrib_left.symm]
lemma filter_mem_eq_inter {s t : finset α} [Π i, decidable (i ∈ t)] :
s.filter (λ i, i ∈ t) = s ∩ t :=
ext $ λ i, by rw [mem_filter, mem_inter]
theorem filter_inter (s t : finset α) : filter p s ∩ t = filter p (s ∩ t) :=
by { ext, simp only [mem_inter, mem_filter, and.right_comm] }
theorem inter_filter (s t : finset α) : s ∩ filter p t = filter p (s ∩ t) :=
by rw [inter_comm, filter_inter, inter_comm]
theorem filter_insert (a : α) (s : finset α) :
filter p (insert a s) = if p a then insert a (filter p s) else filter p s :=
by { ext x, simp, split_ifs with h; by_cases h' : x = a; simp [h, h'] }
theorem filter_or [decidable_pred (λ a, p a ∨ q a)] (s : finset α) :
s.filter (λ a, p a ∨ q a) = s.filter p ∪ s.filter q :=
ext $ λ _, by simp only [mem_filter, mem_union, and_or_distrib_left]
theorem filter_and [decidable_pred (λ a, p a ∧ q a)] (s : finset α) :
s.filter (λ a, p a ∧ q a) = s.filter p ∩ s.filter q :=
ext $ λ _, by simp only [mem_filter, mem_inter, and_comm, and.left_comm, and_self]
theorem filter_not [decidable_pred (λ a, ¬ p a)] (s : finset α) :
s.filter (λ a, ¬ p a) = s \ s.filter p :=
ext $ by simpa only [mem_filter, mem_sdiff, and_comm, not_and] using λ a, and_congr_right $
λ h : a ∈ s, (imp_iff_right h).symm.trans imp_not_comm
theorem sdiff_eq_filter (s₁ s₂ : finset α) :
s₁ \ s₂ = filter (∉ s₂) s₁ := ext $ λ _, by simp only [mem_sdiff, mem_filter]
theorem sdiff_eq_self (s₁ s₂ : finset α) :
s₁ \ s₂ = s₁ ↔ s₁ ∩ s₂ ⊆ ∅ :=
by { simp [subset.antisymm_iff],
split; intro h,
{ transitivity' ((s₁ \ s₂) ∩ s₂), mono, simp },
{ calc s₁ \ s₂
⊇ s₁ \ (s₁ ∩ s₂) : by simp [(⊇)]
... ⊇ s₁ \ ∅ : by mono using [(⊇)]
... ⊇ s₁ : by simp [(⊇)] } }
theorem filter_union_filter_neg_eq [decidable_pred (λ a, ¬ p a)]
(s : finset α) : s.filter p ∪ s.filter (λa, ¬ p a) = s :=
by simp only [filter_not, union_sdiff_of_subset (filter_subset p s)]
theorem filter_inter_filter_neg_eq [decidable_pred (λ a, ¬ p a)]
(s : finset α) : s.filter p ∩ s.filter (λa, ¬ p a) = ∅ :=
by simp only [filter_not, inter_sdiff_self]
lemma subset_union_elim {s : finset α} {t₁ t₂ : set α} (h : ↑s ⊆ t₁ ∪ t₂) :
∃s₁ s₂ : finset α, s₁ ∪ s₂ = s ∧ ↑s₁ ⊆ t₁ ∧ ↑s₂ ⊆ t₂ \ t₁ :=
begin
classical,
refine ⟨s.filter (∈ t₁), s.filter (∉ t₁), _, _ , _⟩,
{ simp [filter_union_right, em] },
{ intro x, simp },
{ intro x, simp, intros hx hx₂, refine ⟨or.resolve_left (h hx) hx₂, hx₂⟩ }
end
/- We can simplify an application of filter where the decidability is inferred in "the wrong way" -/
@[simp] lemma filter_congr_decidable {α} (s : finset α) (p : α → Prop) (h : decidable_pred p)
[decidable_pred p] : @filter α p h s = s.filter p :=
by congr
section classical
open_locale classical
/-- The following instance allows us to write `{x ∈ s | p x}` for `finset.filter p s`.
Since the former notation requires us to define this for all propositions `p`, and `finset.filter`
only works for decidable propositions, the notation `{x ∈ s | p x}` is only compatible with
classical logic because it uses `classical.prop_decidable`.
We don't want to redo all lemmas of `finset.filter` for `has_sep.sep`, so we make sure that `simp`
unfolds the notation `{x ∈ s | p x}` to `finset.filter p s`. If `p` happens to be decidable, the
simp-lemma `finset.filter_congr_decidable` will make sure that `finset.filter` uses the right
instance for decidability.
-/
noncomputable instance {α : Type*} : has_sep α (finset α) := ⟨λ p x, x.filter p⟩
@[simp] lemma sep_def {α : Type*} (s : finset α) (p : α → Prop) : {x ∈ s | p x} = s.filter p := rfl
end classical
/--
After filtering out everything that does not equal a given value, at most that value remains.
This is equivalent to `filter_eq'` with the equality the other way.
-/
-- This is not a good simp lemma, as it would prevent `finset.mem_filter` from firing
-- on, e.g. `x ∈ s.filter(eq b)`.
lemma filter_eq [decidable_eq β] (s : finset β) (b : β) :
s.filter (eq b) = ite (b ∈ s) {b} ∅ :=
begin
split_ifs,
{ ext,
simp only [mem_filter, mem_singleton],
exact ⟨λ h, h.2.symm, by { rintro ⟨h⟩, exact ⟨h, rfl⟩, }⟩ },
{ ext,
simp only [mem_filter, not_and, iff_false, not_mem_empty],
rintros m ⟨e⟩, exact h m, }
end
/--
After filtering out everything that does not equal a given value, at most that value remains.
This is equivalent to `filter_eq` with the equality the other way.
-/
lemma filter_eq' [decidable_eq β] (s : finset β) (b : β) :
s.filter (λ a, a = b) = ite (b ∈ s) {b} ∅ :=
trans (filter_congr (λ _ _, ⟨eq.symm, eq.symm⟩)) (filter_eq s b)
lemma filter_ne [decidable_eq β] (s : finset β) (b : β) :
s.filter (λ a, b ≠ a) = s.erase b :=
by { ext, simp only [mem_filter, mem_erase, ne.def], tauto, }
lemma filter_ne' [decidable_eq β] (s : finset β) (b : β) :
s.filter (λ a, a ≠ b) = s.erase b :=
trans (filter_congr (λ _ _, ⟨ne.symm, ne.symm⟩)) (filter_ne s b)
end filter
/-! ### range -/
section range
variables {n m l : ℕ}
/-- `range n` is the set of natural numbers less than `n`. -/
def range (n : ℕ) : finset ℕ := ⟨_, nodup_range n⟩
@[simp] theorem range_coe (n : ℕ) : (range n).1 = multiset.range n := rfl
@[simp] theorem mem_range : m ∈ range n ↔ m < n := mem_range
@[simp] theorem range_zero : range 0 = ∅ := rfl
@[simp] theorem range_one : range 1 = {0} := rfl
theorem range_succ : range (succ n) = insert n (range n) :=
eq_of_veq $ (range_succ n).trans $ (ndinsert_of_not_mem not_mem_range_self).symm
theorem range_add_one : range (n + 1) = insert n (range n) :=
range_succ
@[simp] theorem not_mem_range_self : n ∉ range n := not_mem_range_self
@[simp] theorem self_mem_range_succ (n : ℕ) : n ∈ range (n + 1) := multiset.self_mem_range_succ n
@[simp] theorem range_subset {n m} : range n ⊆ range m ↔ n ≤ m := range_subset
theorem range_mono : monotone range := λ _ _, range_subset.2
lemma mem_range_succ_iff {a b : ℕ} : a ∈ finset.range b.succ ↔ a ≤ b :=
finset.mem_range.trans nat.lt_succ_iff
lemma mem_range_le {n x : ℕ} (hx : x ∈ range n) : x ≤ n :=
(mem_range.1 hx).le
lemma mem_range_sub_ne_zero {n x : ℕ} (hx : x ∈ range n) : n - x ≠ 0 :=
ne_of_gt $ tsub_pos_of_lt $ mem_range.1 hx
@[simp] lemma nonempty_range_iff : (range n).nonempty ↔ n ≠ 0 :=
⟨λ ⟨k, hk⟩, ((zero_le k).trans_lt $ mem_range.1 hk).ne',
λ h, ⟨0, mem_range.2 $ pos_iff_ne_zero.2 h⟩⟩
@[simp] lemma range_eq_empty_iff : range n = ∅ ↔ n = 0 :=
by rw [← not_nonempty_iff_eq_empty, nonempty_range_iff, not_not]
lemma nonempty_range_succ : (range $ n + 1).nonempty :=
nonempty_range_iff.2 n.succ_ne_zero
end range
/- useful rules for calculations with quantifiers -/
theorem exists_mem_empty_iff (p : α → Prop) : (∃ x, x ∈ (∅ : finset α) ∧ p x) ↔ false :=
by simp only [not_mem_empty, false_and, exists_false]
theorem exists_mem_insert [d : decidable_eq α]
(a : α) (s : finset α) (p : α → Prop) :
(∃ x, x ∈ insert a s ∧ p x) ↔ p a ∨ (∃ x, x ∈ s ∧ p x) :=
by simp only [mem_insert, or_and_distrib_right, exists_or_distrib, exists_eq_left]
theorem forall_mem_empty_iff (p : α → Prop) : (∀ x, x ∈ (∅ : finset α) → p x) ↔ true :=
iff_true_intro $ λ _, false.elim
theorem forall_mem_insert [d : decidable_eq α]
(a : α) (s : finset α) (p : α → Prop) :
(∀ x, x ∈ insert a s → p x) ↔ p a ∧ (∀ x, x ∈ s → p x) :=
by simp only [mem_insert, or_imp_distrib, forall_and_distrib, forall_eq]
end finset
/-- Equivalence between the set of natural numbers which are `≥ k` and `ℕ`, given by `n → n - k`. -/
def not_mem_range_equiv (k : ℕ) : {n // n ∉ range k} ≃ ℕ :=
{ to_fun := λ i, i.1 - k,
inv_fun := λ j, ⟨j + k, by simp⟩,
left_inv :=
begin
assume j,
rw subtype.ext_iff_val,
apply tsub_add_cancel_of_le,
simpa using j.2
end,
right_inv := λ j, add_tsub_cancel_right _ _ }
@[simp] lemma coe_not_mem_range_equiv (k : ℕ) :
(not_mem_range_equiv k : {n // n ∉ range k} → ℕ) = (λ i, i - k) := rfl
@[simp] lemma coe_not_mem_range_equiv_symm (k : ℕ) :
((not_mem_range_equiv k).symm : ℕ → {n // n ∉ range k}) = λ j, ⟨j + k, by simp⟩ := rfl
/-! ### erase_dup on list and multiset -/
namespace multiset
variable [decidable_eq α]
/-- `to_finset s` removes duplicates from the multiset `s` to produce a finset. -/
def to_finset (s : multiset α) : finset α := ⟨_, nodup_erase_dup s⟩
@[simp] theorem to_finset_val (s : multiset α) : s.to_finset.1 = s.erase_dup := rfl
theorem to_finset_eq {s : multiset α} (n : nodup s) : finset.mk s n = s.to_finset :=
finset.val_inj.1 n.erase_dup.symm
lemma nodup.to_finset_inj {l l' : multiset α} (hl : nodup l) (hl' : nodup l')
(h : l.to_finset = l'.to_finset) : l = l' :=
by simpa [←to_finset_eq hl, ←to_finset_eq hl'] using h
@[simp] theorem mem_to_finset {a : α} {s : multiset α} : a ∈ s.to_finset ↔ a ∈ s :=
mem_erase_dup
@[simp] lemma to_finset_zero :
to_finset (0 : multiset α) = ∅ :=
rfl
@[simp] lemma to_finset_cons (a : α) (s : multiset α) :
to_finset (a ::ₘ s) = insert a (to_finset s) :=
finset.eq_of_veq erase_dup_cons
@[simp] lemma to_finset_singleton (a : α) :
to_finset ({a} : multiset α) = {a} :=
by rw [singleton_eq_cons, to_finset_cons, to_finset_zero, is_lawful_singleton.insert_emptyc_eq]
@[simp] lemma to_finset_add (s t : multiset α) :
to_finset (s + t) = to_finset s ∪ to_finset t :=
finset.ext $ by simp
@[simp] lemma to_finset_nsmul (s : multiset α) :
∀(n : ℕ) (hn : n ≠ 0), (n • s).to_finset = s.to_finset
| 0 h := by contradiction
| (n+1) h :=
begin
by_cases n = 0,
{ rw [h, zero_add, one_nsmul] },
{ rw [add_nsmul, to_finset_add, one_nsmul, to_finset_nsmul n h, finset.union_idempotent] }
end
@[simp] lemma to_finset_inter (s t : multiset α) :
to_finset (s ∩ t) = to_finset s ∩ to_finset t :=
finset.ext $ by simp
@[simp] lemma to_finset_union (s t : multiset α) :
(s ∪ t).to_finset = s.to_finset ∪ t.to_finset :=
by ext; simp
theorem to_finset_eq_empty {m : multiset α} : m.to_finset = ∅ ↔ m = 0 :=
finset.val_inj.symm.trans multiset.erase_dup_eq_zero
@[simp] lemma to_finset_subset (m1 m2 : multiset α) :
m1.to_finset ⊆ m2.to_finset ↔ m1 ⊆ m2 :=
by simp only [finset.subset_iff, multiset.subset_iff, multiset.mem_to_finset]
end multiset
namespace finset
@[simp] lemma val_to_finset [decidable_eq α] (s : finset α) : s.val.to_finset = s :=
by { ext, rw [multiset.mem_to_finset, ←mem_def] }
end finset
namespace list
variable [decidable_eq α]
/-- `to_finset l` removes duplicates from the list `l` to produce a finset. -/
def to_finset (l : list α) : finset α := multiset.to_finset l
@[simp] theorem to_finset_val (l : list α) : l.to_finset.1 = (l.erase_dup : multiset α) := rfl
theorem to_finset_eq {l : list α} (n : nodup l) : @finset.mk α l n = l.to_finset :=
multiset.to_finset_eq n
@[simp] theorem mem_to_finset {a : α} {l : list α} : a ∈ l.to_finset ↔ a ∈ l :=
mem_erase_dup
@[simp] theorem to_finset_nil : to_finset (@nil α) = ∅ :=
rfl
@[simp] theorem to_finset_cons {a : α} {l : list α} : to_finset (a :: l) = insert a (to_finset l) :=
finset.eq_of_veq $ by by_cases h : a ∈ l; simp [finset.insert_val', multiset.erase_dup_cons, h]
lemma to_finset_surj_on : set.surj_on to_finset {l : list α | l.nodup} set.univ :=
begin
rintro s -,
cases s with t hl, induction t using quot.ind with l,
refine ⟨l, hl, (to_finset_eq hl).symm⟩
end
theorem to_finset_surjective : surjective (to_finset : list α → finset α) :=
by { intro s, rcases to_finset_surj_on (set.mem_univ s) with ⟨l, -, hls⟩, exact ⟨l, hls⟩ }
lemma to_finset_eq_iff_perm_erase_dup {l l' : list α} :
l.to_finset = l'.to_finset ↔ l.erase_dup ~ l'.erase_dup :=
by simp [finset.ext_iff, perm_ext (nodup_erase_dup _) (nodup_erase_dup _)]
lemma to_finset_eq_of_perm (l l' : list α) (h : l ~ l') :
l.to_finset = l'.to_finset :=
to_finset_eq_iff_perm_erase_dup.mpr h.erase_dup
lemma perm_of_nodup_nodup_to_finset_eq {l l' : list α} (hl : nodup l) (hl' : nodup l')
(h : l.to_finset = l'.to_finset) : l ~ l' :=
begin
rw ←multiset.coe_eq_coe,
exact multiset.nodup.to_finset_inj hl hl' h
end
@[simp] lemma to_finset_append {l l' : list α} :
to_finset (l ++ l') = l.to_finset ∪ l'.to_finset :=
begin
induction l with hd tl hl,
{ simp },
{ simp [hl] }
end
@[simp] lemma to_finset_reverse {l : list α} :
to_finset l.reverse = l.to_finset :=
to_finset_eq_of_perm _ _ (reverse_perm l)
end list
namespace finset
/-! ### map -/
section map
open function
/-- When `f` is an embedding of `α` in `β` and `s` is a finset in `α`, then `s.map f` is the image
finset in `β`. The embedding condition guarantees that there are no duplicates in the image. -/
def map (f : α ↪ β) (s : finset α) : finset β :=
⟨s.1.map f, nodup_map f.2 s.2⟩
@[simp] theorem map_val (f : α ↪ β) (s : finset α) : (map f s).1 = s.1.map f := rfl
@[simp] theorem map_empty (f : α ↪ β) : (∅ : finset α).map f = ∅ := rfl
variables {f : α ↪ β} {s : finset α}
@[simp] theorem mem_map {b : β} : b ∈ s.map f ↔ ∃ a ∈ s, f a = b :=
mem_map.trans $ by simp only [exists_prop]; refl
@[simp] theorem mem_map_equiv {f : α ≃ β} {b : β} :
b ∈ s.map f.to_embedding ↔ f.symm b ∈ s :=
by { rw mem_map, exact ⟨by { rintro ⟨a, H, rfl⟩, simpa }, λ h, ⟨_, h, by simp⟩⟩ }
theorem mem_map' (f : α ↪ β) {a} {s : finset α} : f a ∈ s.map f ↔ a ∈ s :=
mem_map_of_injective f.2
theorem mem_map_of_mem (f : α ↪ β) {a} {s : finset α} : a ∈ s → f a ∈ s.map f :=
(mem_map' _).2
lemma apply_coe_mem_map (f : α ↪ β) (s : finset α) (x : s) : f x ∈ s.map f :=
mem_map_of_mem f x.prop
@[simp, norm_cast] theorem coe_map (f : α ↪ β) (s : finset α) : (s.map f : set β) = f '' s :=
set.ext $ λ x, mem_map.trans set.mem_image_iff_bex.symm
theorem coe_map_subset_range (f : α ↪ β) (s : finset α) : (s.map f : set β) ⊆ set.range f :=
calc ↑(s.map f) = f '' s : coe_map f s
... ⊆ set.range f : set.image_subset_range f ↑s
theorem map_to_finset [decidable_eq α] [decidable_eq β] {s : multiset α} :
s.to_finset.map f = (s.map f).to_finset :=
ext $ λ _, by simp only [mem_map, multiset.mem_map, exists_prop, multiset.mem_to_finset]
@[simp] theorem map_refl : s.map (embedding.refl _) = s :=
ext $ λ _, by simpa only [mem_map, exists_prop] using exists_eq_right
@[simp] theorem map_cast_heq {α β} (h : α = β) (s : finset α) :
s.map (equiv.cast h).to_embedding == s :=
by { subst h, simp }
theorem map_map {g : β ↪ γ} : (s.map f).map g = s.map (f.trans g) :=
eq_of_veq $ by simp only [map_val, multiset.map_map]; refl
@[simp] theorem map_subset_map {s₁ s₂ : finset α} : s₁.map f ⊆ s₂.map f ↔ s₁ ⊆ s₂ :=
⟨λ h x xs, (mem_map' _).1 $ h $ (mem_map' f).2 xs,
λ h, by simp [subset_def, map_subset_map h]⟩
/-- Associate to an embedding `f` from `α` to `β` the order embedding that maps a finset to its
image under `f`. -/
def map_embedding (f : α ↪ β) : finset α ↪o finset β :=
order_embedding.of_map_le_iff (map f) (λ _ _, map_subset_map)
@[simp] theorem map_inj {s₁ s₂ : finset α} : s₁.map f = s₂.map f ↔ s₁ = s₂ :=
(map_embedding f).injective.eq_iff
@[simp] theorem map_embedding_apply : map_embedding f s = map f s := rfl
theorem map_filter {p : β → Prop} [decidable_pred p] :
(s.map f).filter p = (s.filter (p ∘ f)).map f :=
eq_of_veq (map_filter _ _ _)
theorem map_union [decidable_eq α] [decidable_eq β]
{f : α ↪ β} (s₁ s₂ : finset α) : (s₁ ∪ s₂).map f = s₁.map f ∪ s₂.map f :=
coe_injective $ by simp only [coe_map, coe_union, set.image_union]
theorem map_inter [decidable_eq α] [decidable_eq β]
{f : α ↪ β} (s₁ s₂ : finset α) : (s₁ ∩ s₂).map f = s₁.map f ∩ s₂.map f :=
coe_injective $ by simp only [coe_map, coe_inter, set.image_inter f.injective]
@[simp] theorem map_singleton (f : α ↪ β) (a : α) : map f {a} = {f a} :=
coe_injective $ by simp only [coe_map, coe_singleton, set.image_singleton]
@[simp] theorem map_insert [decidable_eq α] [decidable_eq β]
(f : α ↪ β) (a : α) (s : finset α) :
(insert a s).map f = insert (f a) (s.map f) :=
by simp only [insert_eq, map_union, map_singleton]
@[simp] theorem map_eq_empty : s.map f = ∅ ↔ s = ∅ :=
⟨λ h, eq_empty_of_forall_not_mem $
λ a m, ne_empty_of_mem (mem_map_of_mem _ m) h, λ e, e.symm ▸ rfl⟩
lemma attach_map_val {s : finset α} : s.attach.map (embedding.subtype _) = s :=
eq_of_veq $ by rw [map_val, attach_val]; exact attach_map_val _
lemma nonempty.map (h : s.nonempty) (f : α ↪ β) : (s.map f).nonempty :=
let ⟨a, ha⟩ := h in ⟨f a, (mem_map' f).mpr ha⟩
end map
lemma range_add_one' (n : ℕ) :
range (n + 1) = insert 0 ((range n).map ⟨λi, i + 1, assume i j, nat.succ.inj⟩) :=
by ext (⟨⟩ | ⟨n⟩); simp [nat.succ_eq_add_one, nat.zero_lt_succ n]
/-! ### image -/
section image
variables [decidable_eq β]
/-- `image f s` is the forward image of `s` under `f`. -/
def image (f : α → β) (s : finset α) : finset β := (s.1.map f).to_finset
@[simp] theorem image_val (f : α → β) (s : finset α) : (image f s).1 = (s.1.map f).erase_dup := rfl
@[simp] theorem image_empty (f : α → β) : (∅ : finset α).image f = ∅ := rfl
variables {f : α → β} {s : finset α}
@[simp] theorem mem_image {b : β} : b ∈ s.image f ↔ ∃ a ∈ s, f a = b :=
by simp only [mem_def, image_val, mem_erase_dup, multiset.mem_map, exists_prop]
theorem mem_image_of_mem (f : α → β) {a} {s : finset α} (h : a ∈ s) : f a ∈ s.image f :=
mem_image.2 ⟨_, h, rfl⟩
instance [can_lift β α] : can_lift (finset β) (finset α) :=
{ cond := λ s, ∀ x ∈ s, can_lift.cond α x,
coe := image can_lift.coe,
prf :=
begin
rintro ⟨⟨l⟩, hd : l.nodup⟩ hl,
lift l to list α using hl,
refine ⟨⟨l, list.nodup_of_nodup_map _ hd⟩, ext $ λ a, _⟩,
simp
end }
lemma _root_.function.injective.mem_finset_image {f : α → β} (hf : function.injective f)
{s : finset α} {x : α} :
f x ∈ s.image f ↔ x ∈ s :=
begin
refine ⟨λ h, _, finset.mem_image_of_mem f⟩,
obtain ⟨y, hy, heq⟩ := mem_image.1 h,
exact hf heq ▸ hy,
end
lemma filter_mem_image_eq_image (f : α → β) (s : finset α) (t : finset β) (h : ∀ x ∈ s, f x ∈ t) :
t.filter (λ y, y ∈ s.image f) = s.image f :=
by { ext, rw [mem_filter, mem_image],
simp only [and_imp, exists_prop, and_iff_right_iff_imp, exists_imp_distrib],
rintros x xel rfl, exact h _ xel }
lemma fiber_nonempty_iff_mem_image (f : α → β) (s : finset α) (y : β) :
(s.filter (λ x, f x = y)).nonempty ↔ y ∈ s.image f :=
by simp [finset.nonempty]
@[simp, norm_cast] lemma coe_image {f : α → β} : ↑(s.image f) = f '' ↑s :=
set.ext $ λ _, mem_image.trans set.mem_image_iff_bex.symm
lemma nonempty.image (h : s.nonempty) (f : α → β) : (s.image f).nonempty :=
let ⟨a, ha⟩ := h in ⟨f a, mem_image_of_mem f ha⟩
@[simp]
lemma nonempty.image_iff (f : α → β) : (s.image f).nonempty ↔ s.nonempty :=
⟨λ ⟨y, hy⟩, let ⟨x, hx, _⟩ := mem_image.mp hy in ⟨x, hx⟩, λ h, h.image f⟩
theorem image_to_finset [decidable_eq α] {s : multiset α} :
s.to_finset.image f = (s.map f).to_finset :=
ext $ λ _, by simp only [mem_image, multiset.mem_to_finset, exists_prop, multiset.mem_map]
theorem image_val_of_inj_on (H : set.inj_on f s) : (image f s).1 = s.1.map f :=
(nodup_map_on H s.2).erase_dup
@[simp]
theorem image_id [decidable_eq α] : s.image id = s :=
ext $ λ _, by simp only [mem_image, exists_prop, id, exists_eq_right]
@[simp] theorem image_id' [decidable_eq α] : s.image (λ x, x) = s := image_id
theorem image_image [decidable_eq γ] {g : β → γ} : (s.image f).image g = s.image (g ∘ f) :=
eq_of_veq $ by simp only [image_val, erase_dup_map_erase_dup_eq, multiset.map_map]
theorem image_subset_image {s₁ s₂ : finset α} (h : s₁ ⊆ s₂) : s₁.image f ⊆ s₂.image f :=
by simp only [subset_def, image_val, subset_erase_dup', erase_dup_subset',
multiset.map_subset_map h]
theorem image_subset_iff {s : finset α} {t : finset β} {f : α → β} :
s.image f ⊆ t ↔ ∀ x ∈ s, f x ∈ t :=
calc s.image f ⊆ t ↔ f '' ↑s ⊆ ↑t : by norm_cast
... ↔ _ : set.image_subset_iff
theorem image_mono (f : α → β) : monotone (finset.image f) := λ _ _, image_subset_image
theorem coe_image_subset_range : ↑(s.image f) ⊆ set.range f :=
calc ↑(s.image f) = f '' ↑s : coe_image
... ⊆ set.range f : set.image_subset_range f ↑s
theorem image_filter {p : β → Prop} [decidable_pred p] :
(s.image f).filter p = (s.filter (p ∘ f)).image f :=
ext $ λ b, by simp only [mem_filter, mem_image, exists_prop]; exact
⟨by rintro ⟨⟨x, h1, rfl⟩, h2⟩; exact ⟨x, ⟨h1, h2⟩, rfl⟩,
by rintro ⟨x, ⟨h1, h2⟩, rfl⟩; exact ⟨⟨x, h1, rfl⟩, h2⟩⟩
theorem image_union [decidable_eq α] {f : α → β} (s₁ s₂ : finset α) :
(s₁ ∪ s₂).image f = s₁.image f ∪ s₂.image f :=
ext $ λ _, by simp only [mem_image, mem_union, exists_prop, or_and_distrib_right,
exists_or_distrib]
theorem image_inter [decidable_eq α] (s₁ s₂ : finset α) (hf : ∀x y, f x = f y → x = y) :
(s₁ ∩ s₂).image f = s₁.image f ∩ s₂.image f :=
ext $ by simp only [mem_image, exists_prop, mem_inter]; exact λ b,
⟨λ ⟨a, ⟨m₁, m₂⟩, e⟩, ⟨⟨a, m₁, e⟩, ⟨a, m₂, e⟩⟩,
λ ⟨⟨a, m₁, e₁⟩, ⟨a', m₂, e₂⟩⟩, ⟨a, ⟨m₁, hf _ _ (e₂.trans e₁.symm) ▸ m₂⟩, e₁⟩⟩.
@[simp] theorem image_singleton (f : α → β) (a : α) : image f {a} = {f a} :=
ext $ λ x, by simpa only [mem_image, exists_prop, mem_singleton, exists_eq_left] using eq_comm
@[simp] theorem image_insert [decidable_eq α] (f : α → β) (a : α) (s : finset α) :
(insert a s).image f = insert (f a) (s.image f) :=
by simp only [insert_eq, image_singleton, image_union]
@[simp] lemma image_erase [decidable_eq α] {f : α → β} (hf : injective f) (s : finset α) (a : α) :
(s.erase a).image f = (s.image f).erase (f a) :=
begin
ext b,
simp only [mem_image, exists_prop, mem_erase],
split,
{ rintro ⟨a', ⟨haa', ha'⟩, rfl⟩,
exact ⟨hf.ne haa', a', ha', rfl⟩ },
{ rintro ⟨h, a', ha', rfl⟩,
exact ⟨a', ⟨ne_of_apply_ne _ h, ha'⟩, rfl⟩ }
end
@[simp] theorem image_eq_empty : s.image f = ∅ ↔ s = ∅ :=
⟨λ h, eq_empty_of_forall_not_mem $
λ a m, ne_empty_of_mem (mem_image_of_mem _ m) h, λ e, e.symm ▸ rfl⟩
lemma mem_range_iff_mem_finset_range_of_mod_eq' [decidable_eq α] {f : ℕ → α} {a : α} {n : ℕ}
(hn : 0 < n) (h : ∀i, f (i % n) = f i) :
a ∈ set.range f ↔ a ∈ (finset.range n).image (λi, f i) :=
begin
split,
{ rintros ⟨i, hi⟩,
simp only [mem_image, exists_prop, mem_range],
exact ⟨i % n, nat.mod_lt i hn, (rfl.congr hi).mp (h i)⟩ },
{ rintro h,
simp only [mem_image, exists_prop, set.mem_range, mem_range] at *,
rcases h with ⟨i, hi, ha⟩,
use ⟨i, ha⟩ },
end
lemma mem_range_iff_mem_finset_range_of_mod_eq [decidable_eq α] {f : ℤ → α} {a : α} {n : ℕ}
(hn : 0 < n) (h : ∀i, f (i % n) = f i) :
a ∈ set.range f ↔ a ∈ (finset.range n).image (λi, f i) :=
suffices (∃i, f (i % n) = a) ↔ ∃i, i < n ∧ f ↑i = a, by simpa [h],
have hn' : 0 < (n : ℤ), from int.coe_nat_lt.mpr hn,
iff.intro
(assume ⟨i, hi⟩,
have 0 ≤ i % ↑n, from int.mod_nonneg _ (ne_of_gt hn'),
⟨int.to_nat (i % n),
by rw [←int.coe_nat_lt, int.to_nat_of_nonneg this]; exact ⟨int.mod_lt_of_pos i hn', hi⟩⟩)
(assume ⟨i, hi, ha⟩,
⟨i, by rw [int.mod_eq_of_lt (int.coe_zero_le _) (int.coe_nat_lt_coe_nat_of_lt hi), ha]⟩)
@[simp] lemma attach_image_val [decidable_eq α] {s : finset α} : s.attach.image subtype.val = s :=
eq_of_veq $ by rw [image_val, attach_val, multiset.attach_map_val, erase_dup_eq_self]
@[simp] lemma attach_image_coe [decidable_eq α] {s : finset α} : s.attach.image coe = s :=
finset.attach_image_val
@[simp] lemma attach_insert [decidable_eq α] {a : α} {s : finset α} :
attach (insert a s) = insert (⟨a, mem_insert_self a s⟩ : {x // x ∈ insert a s})
((attach s).image (λx, ⟨x.1, mem_insert_of_mem x.2⟩)) :=
ext $ λ ⟨x, hx⟩, ⟨or.cases_on (mem_insert.1 hx)
(λ h : x = a, λ _, mem_insert.2 $ or.inl $ subtype.eq h)
(λ h : x ∈ s, λ _, mem_insert_of_mem $ mem_image.2 $ ⟨⟨x, h⟩, mem_attach _ _, subtype.eq rfl⟩),
λ _, finset.mem_attach _ _⟩
theorem map_eq_image (f : α ↪ β) (s : finset α) : s.map f = s.image f :=
eq_of_veq (s.map f).2.erase_dup.symm
lemma image_const {s : finset α} (h : s.nonempty) (b : β) : s.image (λa, b) = singleton b :=
ext $ assume b', by simp only [mem_image, exists_prop, exists_and_distrib_right,
h.bex, true_and, mem_singleton, eq_comm]
@[simp] lemma map_erase [decidable_eq α] (f : α ↪ β) (s : finset α) (a : α) :
(s.erase a).map f = (s.map f).erase (f a) :=
by { simp_rw map_eq_image, exact s.image_erase f.2 a }
/--
Because `finset.image` requires a `decidable_eq` instances for the target type,
we can only construct a `functor finset` when working classically.
-/
instance [Π P, decidable P] : functor finset :=
{ map := λ α β f s, s.image f, }
instance [Π P, decidable P] : is_lawful_functor finset :=
{ id_map := λ α x, image_id,
comp_map := λ α β γ f g s, image_image.symm, }
/-- Given a finset `s` and a predicate `p`, `s.subtype p` is the finset of `subtype p` whose
elements belong to `s`. -/
protected def subtype {α} (p : α → Prop) [decidable_pred p] (s : finset α) : finset (subtype p) :=
(s.filter p).attach.map ⟨λ x, ⟨x.1, (finset.mem_filter.1 x.2).2⟩,
λ x y H, subtype.eq $ subtype.mk.inj H⟩
@[simp] lemma mem_subtype {p : α → Prop} [decidable_pred p] {s : finset α} :
∀{a : subtype p}, a ∈ s.subtype p ↔ (a : α) ∈ s
| ⟨a, ha⟩ := by simp [finset.subtype, ha]
lemma subtype_eq_empty {p : α → Prop} [decidable_pred p] {s : finset α} :
s.subtype p = ∅ ↔ ∀ x, p x → x ∉ s :=
by simp [ext_iff, subtype.forall, subtype.coe_mk]; refl
@[mono] lemma subtype_mono {p : α → Prop} [decidable_pred p] : monotone (finset.subtype p) :=
λ s t h x hx, mem_subtype.2 $ h $ mem_subtype.1 hx
/-- `s.subtype p` converts back to `s.filter p` with
`embedding.subtype`. -/
@[simp] lemma subtype_map (p : α → Prop) [decidable_pred p] :
(s.subtype p).map (embedding.subtype _) = s.filter p :=
begin
ext x,
simp [and_comm _ (_ = _), @and.left_comm _ (_ = _), and_comm (p x) (x ∈ s)]
end
/-- If all elements of a `finset` satisfy the predicate `p`,
`s.subtype p` converts back to `s` with `embedding.subtype`. -/
lemma subtype_map_of_mem {p : α → Prop} [decidable_pred p] (h : ∀ x ∈ s, p x) :
(s.subtype p).map (embedding.subtype _) = s :=
by rw [subtype_map, filter_true_of_mem h]
/-- If a `finset` of a subtype is converted to the main type with
`embedding.subtype`, all elements of the result have the property of
the subtype. -/
lemma property_of_mem_map_subtype {p : α → Prop} (s : finset {x // p x}) {a : α}
(h : a ∈ s.map (embedding.subtype _)) : p a :=
begin
rcases mem_map.1 h with ⟨x, hx, rfl⟩,
exact x.2
end
/-- If a `finset` of a subtype is converted to the main type with
`embedding.subtype`, the result does not contain any value that does
not satisfy the property of the subtype. -/
lemma not_mem_map_subtype_of_not_property {p : α → Prop} (s : finset {x // p x})
{a : α} (h : ¬ p a) : a ∉ (s.map (embedding.subtype _)) :=
mt s.property_of_mem_map_subtype h
/-- If a `finset` of a subtype is converted to the main type with
`embedding.subtype`, the result is a subset of the set giving the
subtype. -/
lemma map_subtype_subset {t : set α} (s : finset t) :
↑(s.map (embedding.subtype _)) ⊆ t :=
begin
intros a ha,
rw mem_coe at ha,
convert property_of_mem_map_subtype s ha
end
lemma subset_image_iff {f : α → β}
{s : finset β} {t : set α} : ↑s ⊆ f '' t ↔ ∃s' : finset α, ↑s' ⊆ t ∧ s'.image f = s :=
begin
split, swap,
{ rintro ⟨s, hs, rfl⟩, rw [coe_image], exact set.image_subset f hs },
intro h,
letI : can_lift β t := ⟨f ∘ coe, λ y, y ∈ f '' t, λ y ⟨x, hxt, hy⟩, ⟨⟨x, hxt⟩, hy⟩⟩,
lift s to finset t using h,
refine ⟨s.map (embedding.subtype _), map_subtype_subset _, _⟩,
ext y, simp
end
end image
end finset
theorem multiset.to_finset_map [decidable_eq α] [decidable_eq β] (f : α → β) (m : multiset α) :
(m.map f).to_finset = m.to_finset.image f :=
finset.val_inj.1 (multiset.erase_dup_map_erase_dup_eq _ _).symm
namespace finset
/-! ### card -/
section card
/-- `card s` is the cardinality (number of elements) of `s`. -/
def card (s : finset α) : nat := s.1.card
theorem card_def (s : finset α) : s.card = s.1.card := rfl
@[simp] lemma card_mk {m nodup} : (⟨m, nodup⟩ : finset α).card = m.card := rfl
@[simp] theorem card_empty : card (∅ : finset α) = 0 := rfl
theorem card_le_of_subset {s t : finset α} : s ⊆ t → card s ≤ card t :=
multiset.card_le_of_le ∘ val_le_iff.mpr
@[simp] theorem card_eq_zero {s : finset α} : card s = 0 ↔ s = ∅ :=
card_eq_zero.trans val_eq_zero
theorem card_pos {s : finset α} : 0 < card s ↔ s.nonempty :=
pos_iff_ne_zero.trans $ (not_congr card_eq_zero).trans nonempty_iff_ne_empty.symm
alias finset.card_pos ↔ _ finset.nonempty.card_pos
theorem card_ne_zero_of_mem {s : finset α} {a : α} (h : a ∈ s) : card s ≠ 0 :=
(not_congr card_eq_zero).2 (ne_empty_of_mem h)
theorem card_eq_one {s : finset α} : s.card = 1 ↔ ∃ a, s = {a} :=
by cases s; simp only [multiset.card_eq_one, finset.card, ← val_inj, singleton_val]
theorem card_le_one {s : finset α} : s.card ≤ 1 ↔ ∀ (a ∈ s) (b ∈ s), a = b :=
begin
rcases s.eq_empty_or_nonempty with rfl|⟨x, hx⟩, { simp },
refine (nat.succ_le_of_lt (card_pos.2 ⟨x, hx⟩)).le_iff_eq.trans (card_eq_one.trans ⟨_, _⟩),
{ rintro ⟨y, rfl⟩, simp },
{ exact λ h, ⟨x, eq_singleton_iff_unique_mem.2 ⟨hx, λ y hy, h _ hy _ hx⟩⟩ }
end
theorem card_le_one_iff {s : finset α} : s.card ≤ 1 ↔ ∀ {a b}, a ∈ s → b ∈ s → a = b :=
by { rw card_le_one, tauto }
lemma card_le_one_iff_subset_singleton [nonempty α] {s : finset α} :
s.card ≤ 1 ↔ ∃ (x : α), s ⊆ {x} :=
begin
split,
{ assume H,
by_cases h : ∃ x, x ∈ s,
{ rcases h with ⟨x, hx⟩,
refine ⟨x, λ y hy, _⟩,
rw [card_le_one.1 H y hy x hx, mem_singleton] },
{ push_neg at h,
inhabit α,
exact ⟨default α, λ y hy, (h y hy).elim⟩ } },
{ rintros ⟨x, hx⟩,
rw ← card_singleton x,
exact card_le_of_subset hx }
end
/-- A `finset` of a subsingleton type has cardinality at most one. -/
lemma card_le_one_of_subsingleton [subsingleton α] (s : finset α) : s.card ≤ 1 :=
finset.card_le_one_iff.2 $ λ _ _ _ _, subsingleton.elim _ _
theorem one_lt_card {s : finset α} : 1 < s.card ↔ ∃ (a ∈ s) (b ∈ s), a ≠ b :=
by { rw ← not_iff_not, push_neg, exact card_le_one }
lemma exists_ne_of_one_lt_card {s : finset α} (hs : 1 < s.card) (a : α) :
∃ b : α, b ∈ s ∧ b ≠ a :=
begin
obtain ⟨x, hx, y, hy, hxy⟩ := finset.one_lt_card.mp hs,
by_cases ha : y = a,
{ exact ⟨x, hx, ne_of_ne_of_eq hxy ha⟩ },
{ exact ⟨y, hy, ha⟩ },
end
lemma one_lt_card_iff {s : finset α} :
1 < s.card ↔ ∃ x y, (x ∈ s) ∧ (y ∈ s) ∧ x ≠ y :=
by { rw one_lt_card, simp only [exists_prop, exists_and_distrib_left] }
@[simp] theorem card_cons {a : α} {s : finset α} (h : a ∉ s) : card (cons a s h) = card s + 1 :=
card_cons _ _
@[simp] theorem card_insert_of_not_mem [decidable_eq α]
{a : α} {s : finset α} (h : a ∉ s) : card (insert a s) = card s + 1 :=
by rw [← cons_eq_insert _ _ h, card_cons]
theorem card_insert_of_mem [decidable_eq α] {a : α} {s : finset α}
(h : a ∈ s) : card (insert a s) = card s := by rw insert_eq_of_mem h
theorem card_insert_le [decidable_eq α] (a : α) (s : finset α) : card (insert a s) ≤ card s + 1 :=
by by_cases a ∈ s; [{rw [insert_eq_of_mem h], apply nat.le_add_right},
rw [card_insert_of_not_mem h]]
/-- If `a ∈ s` is known, see also `finset.card_insert_of_mem` and
`finset.card_insert_of_not_mem`. -/
theorem card_insert_eq_ite [decidable_eq α] {a : α} {s : finset α} :
card (insert a s) = if a ∈ s then card s else card s + 1 :=
begin
by_cases h : a ∈ s,
{ rw [card_insert_of_mem h, if_pos h] },
{ rw [card_insert_of_not_mem h, if_neg h] },
end
@[simp] theorem card_singleton (a : α) : card ({a} : finset α) = 1 := card_singleton _
lemma card_singleton_inter [decidable_eq α] {x : α} {s : finset α} : ({x} ∩ s).card ≤ 1 :=
begin
cases (finset.decidable_mem x s),
{ simp [finset.singleton_inter_of_not_mem h] },
{ simp [finset.singleton_inter_of_mem h] },
end
@[simp]
theorem card_erase_of_mem [decidable_eq α] {a : α} {s : finset α} :
a ∈ s → card (erase s a) = pred (card s) := card_erase_of_mem
theorem card_erase_lt_of_mem [decidable_eq α] {a : α} {s : finset α} :
a ∈ s → card (erase s a) < card s := card_erase_lt_of_mem
theorem card_erase_le [decidable_eq α] {a : α} {s : finset α} :
card (erase s a) ≤ card s := card_erase_le
theorem pred_card_le_card_erase [decidable_eq α] {a : α} {s : finset α} :
card s - 1 ≤ card (erase s a) :=
begin
by_cases h : a ∈ s,
{ rw [card_erase_of_mem h], refl },
{ rw [erase_eq_of_not_mem h], apply nat.sub_le }
end
/-- If `a ∈ s` is known, see also `finset.card_erase_of_mem` and `finset.erase_eq_of_not_mem`. -/
theorem card_erase_eq_ite [decidable_eq α] {a : α} {s : finset α} :
card (erase s a) = if a ∈ s then pred (card s) else card s := card_erase_eq_ite
@[simp] theorem card_range (n : ℕ) : card (range n) = n := card_range n
@[simp] theorem card_attach {s : finset α} : card (attach s) = card s := multiset.card_attach
end card
end finset
theorem multiset.to_finset_card_le [decidable_eq α] (m : multiset α) : m.to_finset.card ≤ m.card :=
card_le_of_le (erase_dup_le _)
lemma list.card_to_finset [decidable_eq α] (l : list α) :
finset.card l.to_finset = l.erase_dup.length := rfl
theorem list.to_finset_card_le [decidable_eq α] (l : list α) : l.to_finset.card ≤ l.length :=
multiset.to_finset_card_le ⟦l⟧
namespace finset
section card
theorem card_image_le [decidable_eq β] {f : α → β} {s : finset α} : card (image f s) ≤ card s :=
by simpa only [card_map] using (s.1.map f).to_finset_card_le
theorem card_image_of_inj_on [decidable_eq β] {f : α → β} {s : finset α}
(H : set.inj_on f s) : card (image f s) = card s :=
by simp only [card, image_val_of_inj_on H, card_map]
theorem inj_on_of_card_image_eq [decidable_eq β] {f : α → β} {s : finset α}
(H : card (image f s) = card s) :
set.inj_on f s :=
begin
change (s.1.map f).erase_dup.card = s.1.card at H,
have : (s.1.map f).erase_dup = s.1.map f,
{ apply multiset.eq_of_le_of_card_le,
{ apply multiset.erase_dup_le },
rw H,
simp only [multiset.card_map] },
rw multiset.erase_dup_eq_self at this,
apply inj_on_of_nodup_map this,
end
theorem card_image_eq_iff_inj_on [decidable_eq β] {f : α → β} {s : finset α} :
(s.image f).card = s.card ↔ set.inj_on f s :=
⟨inj_on_of_card_image_eq, card_image_of_inj_on⟩
theorem card_image_of_injective [decidable_eq β] {f : α → β} (s : finset α)
(H : injective f) : card (image f s) = card s :=
card_image_of_inj_on $ λ x _ y _ h, H h
lemma fiber_card_ne_zero_iff_mem_image (s : finset α) (f : α → β) [decidable_eq β] (y : β) :
(s.filter (λ x, f x = y)).card ≠ 0 ↔ y ∈ s.image f :=
by { rw [←pos_iff_ne_zero, card_pos, fiber_nonempty_iff_mem_image] }
@[simp] lemma card_map {α β} (f : α ↪ β) {s : finset α} : (s.map f).card = s.card :=
multiset.card_map _ _
@[simp] lemma card_subtype (p : α → Prop) [decidable_pred p] (s : finset α) :
(s.subtype p).card = (s.filter p).card :=
by simp [finset.subtype]
lemma card_eq_of_bijective {s : finset α} {n : ℕ}
(f : ∀i, i < n → α)
(hf : ∀a∈s, ∃i, ∃h:i<n, f i h = a) (hf' : ∀i (h : i < n), f i h ∈ s)
(f_inj : ∀i j (hi : i < n) (hj : j < n), f i hi = f j hj → i = j) :
card s = n :=
begin
classical,
have : ∀ (a : α), a ∈ s ↔ ∃i (hi : i ∈ range n), f i (mem_range.1 hi) = a,
from assume a, ⟨assume ha, let ⟨i, hi, eq⟩ := hf a ha in ⟨i, mem_range.2 hi, eq⟩,
assume ⟨i, hi, eq⟩, eq ▸ hf' i (mem_range.1 hi)⟩,
have : s = ((range n).attach.image $ λi, f i.1 (mem_range.1 i.2)),
by simpa only [ext_iff, mem_image, exists_prop, subtype.exists, mem_attach, true_and],
calc card s = card ((range n).attach.image $ λi, f i.1 (mem_range.1 i.2)) :
by rw [this]
... = card ((range n).attach) :
card_image_of_injective _ $ assume ⟨i, hi⟩ ⟨j, hj⟩ eq,
subtype.eq $ f_inj i j (mem_range.1 hi) (mem_range.1 hj) eq
... = card (range n) : card_attach
... = n : card_range n
end
lemma card_eq_succ [decidable_eq α] {s : finset α} {n : ℕ} :
s.card = n + 1 ↔ (∃a t, a ∉ t ∧ insert a t = s ∧ card t = n) :=
iff.intro
(assume eq,
have 0 < card s, from eq.symm ▸ nat.zero_lt_succ _,
let ⟨a, has⟩ := card_pos.mp this in
⟨a, s.erase a, s.not_mem_erase a, insert_erase has,
by simp only [eq, card_erase_of_mem has, pred_succ]⟩)
(assume ⟨a, t, hat, s_eq, n_eq⟩, s_eq ▸ n_eq ▸ card_insert_of_not_mem hat)
theorem card_filter_le (s : finset α) (p : α → Prop) [decidable_pred p] :
card (s.filter p) ≤ card s :=
card_le_of_subset $ filter_subset _ _
theorem eq_of_subset_of_card_le {s t : finset α} (h : s ⊆ t) (h₂ : card t ≤ card s) : s = t :=
eq_of_veq $ multiset.eq_of_le_of_card_le (val_le_iff.mpr h) h₂
lemma filter_card_eq {s : finset α} {p : α → Prop} [decidable_pred p]
(h : (s.filter p).card = s.card) (x : α) (hx : x ∈ s) : p x :=
begin
rw [←eq_of_subset_of_card_le (s.filter_subset p) h.ge, mem_filter] at hx,
exact hx.2,
end
lemma card_lt_card {s t : finset α} (h : s ⊂ t) : s.card < t.card :=
card_lt_of_lt (val_lt_iff.2 h)
lemma card_le_card_of_inj_on {s : finset α} {t : finset β}
(f : α → β) (hf : ∀a∈s, f a ∈ t) (f_inj : ∀a₁∈s, ∀a₂∈s, f a₁ = f a₂ → a₁ = a₂) :
card s ≤ card t :=
begin
classical,
calc card s = card (s.image f) : by rw [card_image_of_inj_on f_inj]
... ≤ card t : card_le_of_subset $ image_subset_iff.2 hf
end
/--
If there are more pigeons than pigeonholes, then there are two pigeons
in the same pigeonhole.
-/
lemma exists_ne_map_eq_of_card_lt_of_maps_to {s : finset α} {t : finset β} (hc : t.card < s.card)
{f : α → β} (hf : ∀ a ∈ s, f a ∈ t) :
∃ (x ∈ s) (y ∈ s), x ≠ y ∧ f x = f y :=
begin
classical, by_contra hz, push_neg at hz,
refine hc.not_le (card_le_card_of_inj_on f hf _),
intros x hx y hy, contrapose, exact hz x hx y hy,
end
lemma le_card_of_inj_on_range {n} {s : finset α}
(f : ℕ → α) (hf : ∀i<n, f i ∈ s) (f_inj : ∀ (i<n) (j<n), f i = f j → i = j) : n ≤ card s :=
calc n = card (range n) : (card_range n).symm
... ≤ card s : card_le_card_of_inj_on f (by simpa only [mem_range]) (by simpa only [mem_range])
/-- Suppose that, given objects defined on all strict subsets of any finset `s`, one knows how to
define an object on `s`. Then one can inductively define an object on all finsets, starting from
the empty set and iterating. This can be used either to define data, or to prove properties. -/
def strong_induction {p : finset α → Sort*} (H : ∀ s, (∀ t ⊂ s, p t) → p s) :
∀ (s : finset α), p s
| s := H s (λ t h, have card t < card s, from card_lt_card h, strong_induction t)
using_well_founded {rel_tac := λ _ _, `[exact ⟨_, measure_wf card⟩]}
lemma strong_induction_eq {p : finset α → Sort*} (H : ∀ s, (∀ t ⊂ s, p t) → p s) (s : finset α) :
strong_induction H s = H s (λ t h, strong_induction H t) :=
by rw strong_induction
/-- Analogue of `strong_induction` with order of arguments swapped. -/
@[elab_as_eliminator] def strong_induction_on {p : finset α → Sort*} :
∀ (s : finset α), (∀s, (∀ t ⊂ s, p t) → p s) → p s :=
λ s H, strong_induction H s
lemma strong_induction_on_eq {p : finset α → Sort*} (s : finset α) (H : ∀ s, (∀ t ⊂ s, p t) → p s) :
s.strong_induction_on H = H s (λ t h, t.strong_induction_on H) :=
by { dunfold strong_induction_on, rw strong_induction }
@[elab_as_eliminator] lemma case_strong_induction_on [decidable_eq α] {p : finset α → Prop}
(s : finset α) (h₀ : p ∅) (h₁ : ∀ a s, a ∉ s → (∀ t ⊆ s, p t) → p (insert a s)) : p s :=
finset.strong_induction_on s $ λ s,
finset.induction_on s (λ _, h₀) $ λ a s n _ ih, h₁ a s n $
λ t ss, ih _ (lt_of_le_of_lt ss (ssubset_insert n) : t < _)
/-- Suppose that, given that `p t` can be defined on all supersets of `s` of cardinality less than
`n`, one knows how to define `p s`. Then one can inductively define `p s` for all finsets `s` of
cardinality less than `n`, starting from finsets of card `n` and iterating. This
can be used either to define data, or to prove properties. -/
def strong_downward_induction {p : finset α → Sort*} {n : ℕ} (H : ∀ t₁, (∀ {t₂ : finset α},
t₂.card ≤ n → t₁ ⊂ t₂ → p t₂) → t₁.card ≤ n → p t₁) :
∀ (s : finset α), s.card ≤ n → p s
| s := H s (λ t ht h, have n - card t < n - card s,
from (tsub_lt_tsub_iff_left_of_le ht).2 (finset.card_lt_card h),
strong_downward_induction t ht)
using_well_founded {rel_tac := λ _ _, `[exact ⟨_, measure_wf (λ (t : finset α), n - t.card)⟩]}
lemma strong_downward_induction_eq {p : finset α → Sort*} {n : ℕ} (H : ∀ t₁, (∀ {t₂ : finset α},
t₂.card ≤ n → t₁ ⊂ t₂ → p t₂) → t₁.card ≤ n → p t₁) (s : finset α) :
strong_downward_induction H s = H s (λ t ht hst, strong_downward_induction H t ht) :=
by rw strong_downward_induction
/-- Analogue of `strong_downward_induction` with order of arguments swapped. -/
@[elab_as_eliminator] def strong_downward_induction_on {p : finset α → Sort*} {n : ℕ} :
∀ (s : finset α), (∀ t₁, (∀ {t₂ : finset α}, t₂.card ≤ n → t₁ ⊂ t₂ → p t₂) → t₁.card ≤ n → p t₁)
→ s.card ≤ n → p s :=
λ s H, strong_downward_induction H s
lemma strong_downward_induction_on_eq {p : finset α → Sort*} (s : finset α) {n : ℕ} (H : ∀ t₁,
(∀ {t₂ : finset α}, t₂.card ≤ n → t₁ ⊂ t₂ → p t₂) → t₁.card ≤ n → p t₁) :
s.strong_downward_induction_on H = H s (λ t ht h, t.strong_downward_induction_on H ht) :=
by { dunfold strong_downward_induction_on, rw strong_downward_induction }
lemma card_congr {s : finset α} {t : finset β} (f : Π a ∈ s, β)
(h₁ : ∀ a ha, f a ha ∈ t) (h₂ : ∀ a b ha hb, f a ha = f b hb → a = b)
(h₃ : ∀ b ∈ t, ∃ a ha, f a ha = b) : s.card = t.card :=
by haveI := classical.prop_decidable; exact
calc s.card = s.attach.card : card_attach.symm
... = (s.attach.image (λ (a : {a // a ∈ s}), f a.1 a.2)).card :
eq.symm (card_image_of_injective _ (λ a b h, subtype.eq (h₂ _ _ _ _ h)))
... = t.card : congr_arg card (finset.ext $ λ b,
⟨λ h, let ⟨a, ha₁, ha₂⟩ := mem_image.1 h in ha₂ ▸ h₁ _ _,
λ h, let ⟨a, ha₁, ha₂⟩ := h₃ b h in mem_image.2 ⟨⟨a, ha₁⟩, by simp [ha₂]⟩⟩)
lemma card_union_add_card_inter [decidable_eq α] (s t : finset α) :
(s ∪ t).card + (s ∩ t).card = s.card + t.card :=
finset.induction_on t (by simp) $ λ a r har, by by_cases a ∈ s; simp *; cc
lemma card_union_le [decidable_eq α] (s t : finset α) :
(s ∪ t).card ≤ s.card + t.card :=
card_union_add_card_inter s t ▸ nat.le_add_right _ _
lemma card_union_eq [decidable_eq α] {s t : finset α} (h : disjoint s t) :
(s ∪ t).card = s.card + t.card :=
begin
rw [← card_union_add_card_inter],
convert (add_zero _).symm, rw [card_eq_zero], rwa [disjoint_iff] at h
end
lemma surj_on_of_inj_on_of_card_le {s : finset α} {t : finset β}
(f : Π a ∈ s, β) (hf : ∀ a ha, f a ha ∈ t)
(hinj : ∀ a₁ a₂ ha₁ ha₂, f a₁ ha₁ = f a₂ ha₂ → a₁ = a₂)
(hst : card t ≤ card s) :
(∀ b ∈ t, ∃ a ha, b = f a ha) :=
by haveI := classical.dec_eq β; exact
λ b hb,
have h : card (image (λ (a : {a // a ∈ s}), f a a.prop) (attach s)) = card s,
from @card_attach _ s ▸ card_image_of_injective _
(λ ⟨a₁, ha₁⟩ ⟨a₂, ha₂⟩ h, subtype.eq $ hinj _ _ _ _ h),
have h₁ : image (λ a : {a // a ∈ s}, f a a.prop) s.attach = t :=
eq_of_subset_of_card_le (λ b h, let ⟨a, ha₁, ha₂⟩ := mem_image.1 h in
ha₂ ▸ hf _ _) (by simp [hst, h]),
begin
rw ← h₁ at hb,
rcases mem_image.1 hb with ⟨a, ha₁, ha₂⟩,
exact ⟨a, a.2, ha₂.symm⟩,
end
open function
lemma inj_on_of_surj_on_of_card_le {s : finset α} {t : finset β}
(f : Π a ∈ s, β) (hf : ∀ a ha, f a ha ∈ t)
(hsurj : ∀ b ∈ t, ∃ a ha, b = f a ha)
(hst : card s ≤ card t)
⦃a₁ a₂⦄ (ha₁ : a₁ ∈ s) (ha₂ : a₂ ∈ s)
(ha₁a₂: f a₁ ha₁ = f a₂ ha₂) : a₁ = a₂ :=
by haveI : inhabited {x // x ∈ s} := ⟨⟨a₁, ha₁⟩⟩; exact
let f' : {x // x ∈ s} → {x // x ∈ t} := λ x, ⟨f x.1 x.2, hf x.1 x.2⟩ in
let g : {x // x ∈ t} → {x // x ∈ s} :=
@surj_inv _ _ f'
(λ x, let ⟨y, hy₁, hy₂⟩ := hsurj x.1 x.2 in ⟨⟨y, hy₁⟩, subtype.eq hy₂.symm⟩) in
have hg : injective g, from injective_surj_inv _,
have hsg : surjective g, from λ x,
let ⟨y, hy⟩ := surj_on_of_inj_on_of_card_le (λ (x : {x // x ∈ t}) (hx : x ∈ t.attach), g x)
(λ x _, show (g x) ∈ s.attach, from mem_attach _ _)
(λ x y _ _ hxy, hg hxy) (by simpa) x (mem_attach _ _) in
⟨y, hy.snd.symm⟩,
have hif : injective f',
from (left_inverse_of_surjective_of_right_inverse hsg
(right_inverse_surj_inv _)).injective,
subtype.ext_iff_val.1 (@hif ⟨a₁, ha₁⟩ ⟨a₂, ha₂⟩ (subtype.eq ha₁a₂))
end card
section to_list
/-- Produce a list of the elements in the finite set using choice. -/
@[reducible] noncomputable def to_list (s : finset α) : list α := s.1.to_list
lemma nodup_to_list (s : finset α) : s.to_list.nodup :=
by { rw [to_list, ←multiset.coe_nodup, multiset.coe_to_list], exact s.nodup }
@[simp] lemma mem_to_list {a : α} (s : finset α) : a ∈ s.to_list ↔ a ∈ s :=
by { rw [to_list, ←multiset.mem_coe, multiset.coe_to_list], exact iff.rfl }
@[simp] lemma length_to_list (s : finset α) : s.to_list.length = s.card :=
by { rw [to_list, ←multiset.coe_card, multiset.coe_to_list], refl }
@[simp] lemma to_list_empty : (∅ : finset α).to_list = [] :=
by simp [to_list]
@[simp, norm_cast]
lemma coe_to_list (s : finset α) : (s.to_list : multiset α) = s.val :=
by { classical, ext, simp }
@[simp] lemma to_list_to_finset [decidable_eq α] (s : finset α) : s.to_list.to_finset = s :=
by { ext, simp }
lemma exists_list_nodup_eq [decidable_eq α] (s : finset α) :
∃ (l : list α), l.nodup ∧ l.to_finset = s :=
⟨s.to_list, s.nodup_to_list, s.to_list_to_finset⟩
end to_list
section bUnion
/-!
### bUnion
This section is about the bounded union of an indexed family `t : α → finset β` of finite sets
over a finite set `s : finset α`.
-/
variables [decidable_eq β] {s : finset α} {t : α → finset β}
/-- `bUnion s t` is the union of `t x` over `x ∈ s`.
(This was formerly `bind` due to the monad structure on types with `decidable_eq`.) -/
protected def bUnion (s : finset α) (t : α → finset β) : finset β :=
(s.1.bind (λ a, (t a).1)).to_finset
@[simp] theorem bUnion_val (s : finset α) (t : α → finset β) :
(s.bUnion t).1 = (s.1.bind (λ a, (t a).1)).erase_dup := rfl
@[simp] theorem bUnion_empty : finset.bUnion ∅ t = ∅ := rfl
@[simp] theorem mem_bUnion {b : β} : b ∈ s.bUnion t ↔ ∃a∈s, b ∈ t a :=
by simp only [mem_def, bUnion_val, mem_erase_dup, mem_bind, exists_prop]
@[simp] theorem bUnion_insert [decidable_eq α] {a : α} : (insert a s).bUnion t = t a ∪ s.bUnion t :=
ext $ λ x, by simp only [mem_bUnion, exists_prop, mem_union, mem_insert,
or_and_distrib_right, exists_or_distrib, exists_eq_left]
-- ext $ λ x, by simp [or_and_distrib_right, exists_or_distrib]
theorem bUnion_congr {s₁ s₂ : finset α} {t₁ t₂ : α → finset β}
(hs : s₁ = s₂) (ht : ∀ a ∈ s₁, t₁ a = t₂ a) :
s₁.bUnion t₁ = s₂.bUnion t₂ :=
ext $ λ x, by simp [hs, ht] { contextual := tt }
theorem bUnion_subset {s' : finset β} : s.bUnion t ⊆ s' ↔ ∀ x ∈ s, t x ⊆ s' :=
by simp only [subset_iff, mem_bUnion]; exact
⟨λ H a ha b hb, H ⟨a, ha, hb⟩, λ H b ⟨a, ha, hb⟩, H a ha hb⟩
@[simp] lemma singleton_bUnion {a : α} : finset.bUnion {a} t = t a :=
begin
classical,
rw [← insert_emptyc_eq, bUnion_insert, bUnion_empty, union_empty]
end
theorem bUnion_inter (s : finset α) (f : α → finset β) (t : finset β) :
s.bUnion f ∩ t = s.bUnion (λ x, f x ∩ t) :=
begin
ext x,
simp only [mem_bUnion, mem_inter],
tauto
end
theorem inter_bUnion (t : finset β) (s : finset α) (f : α → finset β) :
t ∩ s.bUnion f = s.bUnion (λ x, t ∩ f x) :=
by rw [inter_comm, bUnion_inter]; simp [inter_comm]
theorem image_bUnion [decidable_eq γ] {f : α → β} {s : finset α} {t : β → finset γ} :
(s.image f).bUnion t = s.bUnion (λa, t (f a)) :=
by haveI := classical.dec_eq α; exact
finset.induction_on s rfl (λ a s has ih,
by simp only [image_insert, bUnion_insert, ih])
theorem bUnion_image [decidable_eq γ] {s : finset α} {t : α → finset β} {f : β → γ} :
(s.bUnion t).image f = s.bUnion (λa, (t a).image f) :=
by haveI := classical.dec_eq α; exact
finset.induction_on s rfl (λ a s has ih,
by simp only [bUnion_insert, image_union, ih])
lemma bUnion_bUnion [decidable_eq γ] (s : finset α) (f : α → finset β) (g : β → finset γ) :
(s.bUnion f).bUnion g = s.bUnion (λ a, (f a).bUnion g) :=
begin
ext,
simp only [finset.mem_bUnion, exists_prop],
simp_rw [←exists_and_distrib_right, ←exists_and_distrib_left, and_assoc],
rw exists_comm,
end
theorem bind_to_finset [decidable_eq α] (s : multiset α) (t : α → multiset β) :
(s.bind t).to_finset = s.to_finset.bUnion (λa, (t a).to_finset) :=
ext $ λ x, by simp only [multiset.mem_to_finset, mem_bUnion, multiset.mem_bind, exists_prop]
lemma bUnion_mono {t₁ t₂ : α → finset β} (h : ∀a∈s, t₁ a ⊆ t₂ a) : s.bUnion t₁ ⊆ s.bUnion t₂ :=
have ∀b a, a ∈ s → b ∈ t₁ a → (∃ (a : α), a ∈ s ∧ b ∈ t₂ a),
from assume b a ha hb, ⟨a, ha, finset.mem_of_subset (h a ha) hb⟩,
by simpa only [subset_iff, mem_bUnion, exists_imp_distrib, and_imp, exists_prop]
lemma bUnion_subset_bUnion_of_subset_left {α : Type*} {s₁ s₂ : finset α}
(t : α → finset β) (h : s₁ ⊆ s₂) : s₁.bUnion t ⊆ s₂.bUnion t :=
begin
intro x,
simp only [and_imp, mem_bUnion, exists_prop],
exact Exists.imp (λ a ha, ⟨h ha.1, ha.2⟩)
end
lemma subset_bUnion_of_mem {s : finset α}
(u : α → finset β) {x : α} (xs : x ∈ s) :
u x ⊆ s.bUnion u :=
begin
apply subset.trans _ (bUnion_subset_bUnion_of_subset_left u (singleton_subset_iff.2 xs)),
exact subset_of_eq singleton_bUnion.symm,
end
@[simp] lemma bUnion_subset_iff_forall_subset {α β : Type*} [decidable_eq β]
{s : finset α} {t : finset β} {f : α → finset β} : s.bUnion f ⊆ t ↔ ∀ x ∈ s, f x ⊆ t :=
⟨λ h x hx, (subset_bUnion_of_mem f hx).trans h,
λ h x hx, let ⟨a, ha₁, ha₂⟩ := mem_bUnion.mp hx in h _ ha₁ ha₂⟩
lemma bUnion_singleton {f : α → β} : s.bUnion (λa, {f a}) = s.image f :=
ext $ λ x, by simp only [mem_bUnion, mem_image, mem_singleton, eq_comm]
@[simp] lemma bUnion_singleton_eq_self [decidable_eq α] :
s.bUnion (singleton : α → finset α) = s :=
by { rw bUnion_singleton, exact image_id }
lemma bUnion_filter_eq_of_maps_to [decidable_eq α] {s : finset α} {t : finset β} {f : α → β}
(h : ∀ x ∈ s, f x ∈ t) :
t.bUnion (λa, s.filter $ (λc, f c = a)) = s :=
ext $ λ b, by simpa using h b
lemma image_bUnion_filter_eq [decidable_eq α] (s : finset β) (g : β → α) :
(s.image g).bUnion (λa, s.filter $ (λc, g c = a)) = s :=
bUnion_filter_eq_of_maps_to (λ x, mem_image_of_mem g)
lemma erase_bUnion (f : α → finset β) (s : finset α) (b : β) :
(s.bUnion f).erase b = s.bUnion (λ x, (f x).erase b) :=
by { ext, simp only [finset.mem_bUnion, iff_self, exists_and_distrib_left, finset.mem_erase] }
@[simp] lemma bUnion_nonempty : (s.bUnion t).nonempty ↔ ∃ x ∈ s, (t x).nonempty :=
by simp [finset.nonempty, ← exists_and_distrib_left, @exists_swap α]
lemma nonempty.bUnion (hs : s.nonempty) (ht : ∀ x ∈ s, (t x).nonempty) :
(s.bUnion t).nonempty :=
bUnion_nonempty.2 $ hs.imp $ λ x hx, ⟨hx, ht x hx⟩
end bUnion
/-! ### sigma -/
section sigma
variables {σ : α → Type*} {s : finset α} {t : Πa, finset (σ a)}
/-- `sigma s t` is the set of dependent pairs `⟨a, b⟩` such that `a ∈ s` and `b ∈ t a`. -/
protected def sigma (s : finset α) (t : Πa, finset (σ a)) : finset (Σa, σ a) :=
⟨_, nodup_sigma s.2 (λ a, (t a).2)⟩
@[simp] theorem mem_sigma {p : sigma σ} : p ∈ s.sigma t ↔ p.1 ∈ s ∧ p.2 ∈ t (p.1) := mem_sigma
@[simp] theorem sigma_nonempty : (s.sigma t).nonempty ↔ ∃ x ∈ s, (t x).nonempty :=
by simp [finset.nonempty]
@[simp] theorem sigma_eq_empty : s.sigma t = ∅ ↔ ∀ x ∈ s, t x = ∅ :=
by simp only [← not_nonempty_iff_eq_empty, sigma_nonempty, not_exists]
@[mono] theorem sigma_mono {s₁ s₂ : finset α} {t₁ t₂ : Πa, finset (σ a)}
(H1 : s₁ ⊆ s₂) (H2 : ∀a, t₁ a ⊆ t₂ a) : s₁.sigma t₁ ⊆ s₂.sigma t₂ :=
λ ⟨x, sx⟩ H, let ⟨H3, H4⟩ := mem_sigma.1 H in mem_sigma.2 ⟨H1 H3, H2 x H4⟩
theorem sigma_eq_bUnion [decidable_eq (Σ a, σ a)] (s : finset α)
(t : Πa, finset (σ a)) :
s.sigma t = s.bUnion (λa, (t a).map $ embedding.sigma_mk a) :=
by { ext ⟨x, y⟩, simp [and.left_comm] }
end sigma
/-! ### disjoint -/
section disjoint
variable [decidable_eq α]
theorem disjoint_left {s t : finset α} : disjoint s t ↔ ∀ {a}, a ∈ s → a ∉ t :=
by simp only [_root_.disjoint, inf_eq_inter, le_iff_subset, subset_iff, mem_inter, not_and,
and_imp]; refl
theorem disjoint_val {s t : finset α} : disjoint s t ↔ s.1.disjoint t.1 :=
disjoint_left
theorem disjoint_iff_inter_eq_empty {s t : finset α} : disjoint s t ↔ s ∩ t = ∅ :=
disjoint_iff
instance decidable_disjoint (U V : finset α) : decidable (disjoint U V) :=
decidable_of_decidable_of_iff (by apply_instance) eq_bot_iff
theorem disjoint_right {s t : finset α} : disjoint s t ↔ ∀ {a}, a ∈ t → a ∉ s :=
by rw [disjoint.comm, disjoint_left]
theorem disjoint_iff_ne {s t : finset α} : disjoint s t ↔ ∀ a ∈ s, ∀ b ∈ t, a ≠ b :=
by simp only [disjoint_left, imp_not_comm, forall_eq']
lemma not_disjoint_iff {s t : finset α} :
¬disjoint s t ↔ ∃ a, a ∈ s ∧ a ∈ t :=
not_forall.trans $ exists_congr $ λ a, begin
rw [finset.inf_eq_inter, finset.mem_inter],
exact not_not,
end
theorem disjoint_of_subset_left {s t u : finset α} (h : s ⊆ u) (d : disjoint u t) : disjoint s t :=
disjoint_left.2 (λ x m₁, (disjoint_left.1 d) (h m₁))
theorem disjoint_of_subset_right {s t u : finset α} (h : t ⊆ u) (d : disjoint s u) : disjoint s t :=
disjoint_right.2 (λ x m₁, (disjoint_right.1 d) (h m₁))
@[simp] theorem disjoint_empty_left (s : finset α) : disjoint ∅ s := disjoint_bot_left
@[simp] theorem disjoint_empty_right (s : finset α) : disjoint s ∅ := disjoint_bot_right
@[simp] theorem disjoint_singleton_left {s : finset α} {a : α} : disjoint (singleton a) s ↔ a ∉ s :=
by simp only [disjoint_left, mem_singleton, forall_eq]
@[simp] theorem disjoint_singleton_right {s : finset α} {a : α} :
disjoint s (singleton a) ↔ a ∉ s :=
disjoint.comm.trans disjoint_singleton_left
@[simp] lemma disjoint_singleton {a b : α} : disjoint ({a} : finset α) {b} ↔ a ≠ b :=
by rw [disjoint_singleton_left, mem_singleton]
@[simp] theorem disjoint_insert_left {a : α} {s t : finset α} :
disjoint (insert a s) t ↔ a ∉ t ∧ disjoint s t :=
by simp only [disjoint_left, mem_insert, or_imp_distrib, forall_and_distrib, forall_eq]
@[simp] theorem disjoint_insert_right {a : α} {s t : finset α} :
disjoint s (insert a t) ↔ a ∉ s ∧ disjoint s t :=
disjoint.comm.trans $ by rw [disjoint_insert_left, disjoint.comm]
@[simp] theorem disjoint_union_left {s t u : finset α} :
disjoint (s ∪ t) u ↔ disjoint s u ∧ disjoint t u :=
by simp only [disjoint_left, mem_union, or_imp_distrib, forall_and_distrib]
@[simp] theorem disjoint_union_right {s t u : finset α} :
disjoint s (t ∪ u) ↔ disjoint s t ∧ disjoint s u :=
by simp only [disjoint_right, mem_union, or_imp_distrib, forall_and_distrib]
lemma sdiff_disjoint {s t : finset α} : disjoint (t \ s) s :=
disjoint_left.2 $ assume a ha, (mem_sdiff.1 ha).2
lemma disjoint_sdiff {s t : finset α} : disjoint s (t \ s) :=
sdiff_disjoint.symm
lemma disjoint_sdiff_inter (s t : finset α) : disjoint (s \ t) (s ∩ t) :=
disjoint_of_subset_right (inter_subset_right _ _) sdiff_disjoint
lemma sdiff_eq_self_iff_disjoint {s t : finset α} : s \ t = s ↔ disjoint s t :=
by rw [sdiff_eq_self, subset_empty, disjoint_iff_inter_eq_empty]
lemma sdiff_eq_self_of_disjoint {s t : finset α} (h : disjoint s t) : s \ t = s :=
sdiff_eq_self_iff_disjoint.2 h
lemma disjoint_self_iff_empty (s : finset α) : disjoint s s ↔ s = ∅ :=
disjoint_self
lemma disjoint_bUnion_left {ι : Type*}
(s : finset ι) (f : ι → finset α) (t : finset α) :
disjoint (s.bUnion f) t ↔ (∀i∈s, disjoint (f i) t) :=
begin
classical,
refine s.induction _ _,
{ simp only [forall_mem_empty_iff, bUnion_empty, disjoint_empty_left] },
{ assume i s his ih,
simp only [disjoint_union_left, bUnion_insert, his, forall_mem_insert, ih] }
end
lemma disjoint_bUnion_right {ι : Type*}
(s : finset α) (t : finset ι) (f : ι → finset α) :
disjoint s (t.bUnion f) ↔ (∀i∈t, disjoint s (f i)) :=
by simpa only [disjoint.comm] using disjoint_bUnion_left t f s
@[simp] theorem card_disjoint_union {s t : finset α} (h : disjoint s t) :
card (s ∪ t) = card s + card t :=
by rw [← card_union_add_card_inter, disjoint_iff_inter_eq_empty.1 h, card_empty, add_zero]
theorem card_sdiff {s t : finset α} (h : s ⊆ t) : card (t \ s) = card t - card s :=
suffices card (t \ s) = card ((t \ s) ∪ s) - card s, by rwa sdiff_union_of_subset h at this,
by rw [card_disjoint_union sdiff_disjoint, add_tsub_cancel_right]
lemma card_sdiff_add_card {s t : finset α} : (s \ t).card + t.card = (s ∪ t).card :=
by rw [← card_disjoint_union sdiff_disjoint, sdiff_union_self_eq_union]
lemma disjoint_filter {s : finset α} {p q : α → Prop} [decidable_pred p] [decidable_pred q] :
disjoint (s.filter p) (s.filter q) ↔ (∀ x ∈ s, p x → ¬ q x) :=
by split; simp [disjoint_left] {contextual := tt}
lemma disjoint_filter_filter {s t : finset α} {p q : α → Prop} [decidable_pred p]
[decidable_pred q] :
(disjoint s t) → disjoint (s.filter p) (t.filter q) :=
disjoint.mono (filter_subset _ _) (filter_subset _ _)
lemma disjoint_iff_disjoint_coe {α : Type*} {a b : finset α} [decidable_eq α] :
disjoint a b ↔ disjoint (↑a : set α) (↑b : set α) :=
by { rw [finset.disjoint_left, set.disjoint_left], refl }
lemma filter_card_add_filter_neg_card_eq_card {α : Type*} {s : finset α} (p : α → Prop)
[decidable_pred p] :
(s.filter p).card + (s.filter (not ∘ p)).card = s.card :=
by { classical, simp [← card_union_eq, filter_union_filter_neg_eq, disjoint_filter], }
end disjoint
/--
Given a set A and a set B inside it, we can shrink A to any appropriate size, and keep B
inside it.
-/
lemma exists_intermediate_set {A B : finset α} (i : ℕ)
(h₁ : i + card B ≤ card A) (h₂ : B ⊆ A) :
∃ (C : finset α), B ⊆ C ∧ C ⊆ A ∧ card C = i + card B :=
begin
classical,
rcases nat.le.dest h₁ with ⟨k, _⟩,
clear h₁,
induction k with k ih generalizing A,
{ exact ⟨A, h₂, subset.refl _, h.symm⟩ },
{ have : (A \ B).nonempty,
{ rw [← card_pos, card_sdiff h₂, ← h, nat.add_right_comm,
add_tsub_cancel_right, nat.add_succ],
apply nat.succ_pos },
rcases this with ⟨a, ha⟩,
have z : i + card B + k = card (erase A a),
{ rw [card_erase_of_mem, ← h, nat.add_succ, nat.pred_succ],
rw mem_sdiff at ha,
exact ha.1 },
rcases ih _ z with ⟨B', hB', B'subA', cards⟩,
{ exact ⟨B', hB', trans B'subA' (erase_subset _ _), cards⟩ },
{ rintros t th,
apply mem_erase_of_ne_of_mem _ (h₂ th),
rintro rfl,
exact not_mem_sdiff_of_mem_right th ha } }
end
/-- We can shrink A to any smaller size. -/
lemma exists_smaller_set (A : finset α) (i : ℕ) (h₁ : i ≤ card A) :
∃ (B : finset α), B ⊆ A ∧ card B = i :=
let ⟨B, _, x₁, x₂⟩ := exists_intermediate_set i (by simpa) (empty_subset A) in ⟨B, x₁, x₂⟩
lemma exists_subset_or_subset_of_two_mul_lt_card [decidable_eq α] {X Y : finset α} {n : ℕ}
(hXY : 2 * n < (X ∪ Y).card) :
∃ C : finset α, n < C.card ∧ (C ⊆ X ∨ C ⊆ Y) :=
begin
have h₁ : (X ∩ (Y \ X)).card = 0 := finset.card_eq_zero.mpr (finset.inter_sdiff_self X Y),
have h₂ : (X ∪ Y).card = X.card + (Y \ X).card,
{ rw [← card_union_add_card_inter X (Y \ X), finset.union_sdiff_self_eq_union, h₁, add_zero] },
rw [h₂, two_mul] at hXY,
rcases lt_or_lt_of_add_lt_add hXY with h|h,
{ exact ⟨X, h, or.inl (finset.subset.refl X)⟩ },
{ exact ⟨Y \ X, h, or.inr (finset.sdiff_subset Y X)⟩ }
end
/-- `finset.fin_range k` is the finset `{0, 1, ..., k-1}`, as a `finset (fin k)`. -/
def fin_range (k : ℕ) : finset (fin k) :=
⟨list.fin_range k, list.nodup_fin_range k⟩
@[simp]
lemma fin_range_card {k : ℕ} : (fin_range k).card = k :=
by simp [fin_range]
@[simp]
lemma mem_fin_range {k : ℕ} (m : fin k) : m ∈ fin_range k :=
list.mem_fin_range m
@[simp] lemma coe_fin_range (k : ℕ) : (fin_range k : set (fin k)) = set.univ :=
set.eq_univ_of_forall mem_fin_range
/-- Given a finset `s` of `ℕ` contained in `{0,..., n-1}`, the corresponding finset in `fin n`
is `s.attach_fin h` where `h` is a proof that all elements of `s` are less than `n`. -/
def attach_fin (s : finset ℕ) {n : ℕ} (h : ∀ m ∈ s, m < n) : finset (fin n) :=
⟨s.1.pmap (λ a ha, ⟨a, ha⟩) h, multiset.nodup_pmap (λ _ _ _ _, fin.veq_of_eq) s.2⟩
@[simp] lemma mem_attach_fin {n : ℕ} {s : finset ℕ} (h : ∀ m ∈ s, m < n) {a : fin n} :
a ∈ s.attach_fin h ↔ (a : ℕ) ∈ s :=
⟨λ h, let ⟨b, hb₁, hb₂⟩ := multiset.mem_pmap.1 h in hb₂ ▸ hb₁,
λ h, multiset.mem_pmap.2 ⟨a, h, fin.eta _ _⟩⟩
@[simp] lemma card_attach_fin {n : ℕ} (s : finset ℕ) (h : ∀ m ∈ s, m < n) :
(s.attach_fin h).card = s.card := multiset.card_pmap _ _ _
/-! ### choose -/
section choose
variables (p : α → Prop) [decidable_pred p] (l : finset α)
/-- Given a finset `l` and a predicate `p`, associate to a proof that there is a unique element of
`l` satisfying `p` this unique element, as an element of the corresponding subtype. -/
def choose_x (hp : (∃! a, a ∈ l ∧ p a)) : { a // a ∈ l ∧ p a } :=
multiset.choose_x p l.val hp
/-- Given a finset `l` and a predicate `p`, associate to a proof that there is a unique element of
`l` satisfying `p` this unique element, as an element of the ambient type. -/
def choose (hp : ∃! a, a ∈ l ∧ p a) : α := choose_x p l hp
lemma choose_spec (hp : ∃! a, a ∈ l ∧ p a) : choose p l hp ∈ l ∧ p (choose p l hp) :=
(choose_x p l hp).property
lemma choose_mem (hp : ∃! a, a ∈ l ∧ p a) : choose p l hp ∈ l := (choose_spec _ _ _).1
lemma choose_property (hp : ∃! a, a ∈ l ∧ p a) : p (choose p l hp) := (choose_spec _ _ _).2
end choose
theorem lt_wf {α} : well_founded (@has_lt.lt (finset α) _) :=
have H : subrelation (@has_lt.lt (finset α) _)
(inv_image (<) card),
from λ x y hxy, card_lt_card hxy,
subrelation.wf H $ inv_image.wf _ $ nat.lt_wf
end finset
namespace equiv
/-- Given an equivalence `α` to `β`, produce an equivalence between `finset α` and `finset β`. -/
protected def finset_congr (e : α ≃ β) : finset α ≃ finset β :=
{ to_fun := λ s, s.map e.to_embedding,
inv_fun := λ s, s.map e.symm.to_embedding,
left_inv := λ s, by simp [finset.map_map],
right_inv := λ s, by simp [finset.map_map] }
@[simp] lemma finset_congr_apply (e : α ≃ β) (s : finset α) :
e.finset_congr s = s.map e.to_embedding :=
rfl
@[simp] lemma finset_congr_refl :
(equiv.refl α).finset_congr = equiv.refl _ :=
by { ext, simp }
@[simp] lemma finset_congr_symm (e : α ≃ β) :
e.finset_congr.symm = e.symm.finset_congr :=
rfl
@[simp] lemma finset_congr_trans (e : α ≃ β) (e' : β ≃ γ) :
e.finset_congr.trans (e'.finset_congr) = (e.trans e').finset_congr :=
by { ext, simp [-finset.mem_map, -equiv.trans_to_embedding] }
end equiv
namespace multiset
variable [decidable_eq α]
theorem to_finset_card_of_nodup {l : multiset α} (h : l.nodup) : l.to_finset.card = l.card :=
congr_arg card $ multiset.erase_dup_eq_self.mpr h
lemma disjoint_to_finset {m1 m2 : multiset α} :
_root_.disjoint m1.to_finset m2.to_finset ↔ m1.disjoint m2 :=
begin
rw finset.disjoint_iff_ne,
split,
{ intro h,
intros a ha1 ha2,
rw ← multiset.mem_to_finset at ha1 ha2,
exact h _ ha1 _ ha2 rfl },
{ rintros h a ha b hb rfl,
rw multiset.mem_to_finset at ha hb,
exact h ha hb }
end
end multiset
namespace list
variable [decidable_eq α]
theorem to_finset_card_of_nodup {l : list α} (h : l.nodup) : l.to_finset.card = l.length :=
multiset.to_finset_card_of_nodup h
lemma disjoint_to_finset_iff_disjoint {l l' : list α} :
_root_.disjoint l.to_finset l'.to_finset ↔ l.disjoint l' :=
multiset.disjoint_to_finset
end list
|
d8dbecc3be3f9854908b1270094c246f145d1339 | 957a80ea22c5abb4f4670b250d55534d9db99108 | /library/init/meta/simp_tactic.lean | de49e14e520d51e9e010d839ffbb9670fd3e29f3 | [
"Apache-2.0"
] | permissive | GaloisInc/lean | aa1e64d604051e602fcf4610061314b9a37ab8cd | f1ec117a24459b59c6ff9e56a1d09d9e9e60a6c0 | refs/heads/master | 1,592,202,909,807 | 1,504,624,387,000 | 1,504,624,387,000 | 75,319,626 | 2 | 1 | Apache-2.0 | 1,539,290,164,000 | 1,480,616,104,000 | C++ | UTF-8 | Lean | false | false | 21,693 | lean | /-
Copyright (c) 2016 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
prelude
import init.meta.tactic init.meta.attribute init.meta.constructor_tactic
import init.meta.relation_tactics init.meta.occurrences
import init.data.option.instances
open tactic
def simp.default_max_steps := 10000000
meta constant simp_lemmas : Type
meta constant simp_lemmas.mk : simp_lemmas
meta constant simp_lemmas.join : simp_lemmas → simp_lemmas → simp_lemmas
meta constant simp_lemmas.erase : simp_lemmas → list name → simp_lemmas
meta constant simp_lemmas.mk_default : tactic simp_lemmas
meta constant simp_lemmas.add : simp_lemmas → expr → tactic simp_lemmas
meta constant simp_lemmas.add_simp : simp_lemmas → name → tactic simp_lemmas
meta constant simp_lemmas.add_congr : simp_lemmas → name → tactic simp_lemmas
meta def simp_lemmas.append (s : simp_lemmas) (hs : list expr) : tactic simp_lemmas :=
hs.mfoldl simp_lemmas.add s
/-- `simp_lemmas.rewrite_core s e prove R` apply a simplification lemma from 's'
- 'e' is the expression to be "simplified"
- 'prove' is used to discharge proof obligations.
- 'r' is the equivalence relation being used (e.g., 'eq', 'iff')
Result (new_e, pr) is the new expression 'new_e' and a proof (pr : e R new_e) -/
meta constant simp_lemmas.rewrite (s : simp_lemmas) (e : expr)
(prove : tactic unit := failed) (r : name := `eq) (md := reducible)
: tactic (expr × expr)
/-- `simp_lemmas.drewrite s e` tries to rewrite 'e' using only refl lemmas in 's' -/
meta constant simp_lemmas.drewrite (s : simp_lemmas) (e : expr) (md := reducible) : tactic expr
meta constant is_valid_simp_lemma_cnst : name → tactic bool
meta constant is_valid_simp_lemma : expr → tactic bool
meta constant simp_lemmas.pp : simp_lemmas → tactic format
meta instance : has_to_tactic_format simp_lemmas :=
⟨simp_lemmas.pp⟩
namespace tactic
meta def revert_and_transform (transform : expr → tactic expr) (h : expr) : tactic unit :=
do num_reverted : ℕ ← revert h,
t ← target,
match t with
| expr.pi n bi d b :=
do h_simp ← transform d,
unsafe_change $ expr.pi n bi h_simp b
| expr.elet n g e f :=
do h_simp ← transform g,
unsafe_change $ expr.elet n h_simp e f
| _ := fail "reverting hypothesis created neither a pi nor an elet expr (unreachable?)"
end,
intron num_reverted
/-- `get_eqn_lemmas_for deps d` returns the automatically generated equational lemmas for definition d.
If deps is tt, then lemmas for automatically generated auxiliary declarations used to define d are also included. -/
meta constant get_eqn_lemmas_for : bool → name → tactic (list name)
structure dsimp_config :=
(md := reducible)
(max_steps : nat := simp.default_max_steps)
(canonize_instances : bool := tt)
(single_pass : bool := ff)
(fail_if_unchanged := tt)
(eta := tt)
(zeta : bool := tt)
(beta : bool := tt)
(proj : bool := tt) -- reduce projections
(iota : bool := tt)
(unfold_reducible := ff) -- if tt, reducible definitions will be unfolded (delta-reduced)
(memoize := tt)
end tactic
/-- (Definitional) Simplify the given expression using *only* reflexivity equality lemmas from the given set of lemmas.
The resulting expression is definitionally equal to the input.
The list `u` contains defintions to be delta-reduced, and projections to be reduced.-/
meta constant simp_lemmas.dsimplify (s : simp_lemmas) (u : list name := []) (e : expr) (cfg : tactic.dsimp_config := {}) : tactic expr
namespace tactic
/- Remark: the configuration parameters `cfg.md` and `cfg.eta` are ignored by this tactic. -/
meta constant dsimplify_core
/- The user state type. -/
{α : Type}
/- Initial user data -/
(a : α)
/- (pre a e) is invoked before visiting the children of subterm 'e',
if it succeeds the result (new_a, new_e, flag) where
- 'new_a' is the new value for the user data
- 'new_e' is a new expression that must be definitionally equal to 'e',
- 'flag' if tt 'new_e' children should be visited, and 'post' invoked. -/
(pre : α → expr → tactic (α × expr × bool))
/- (post a e) is invoked after visiting the children of subterm 'e',
The output is similar to (pre a e), but the 'flag' indicates whether
the new expression should be revisited or not. -/
(post : α → expr → tactic (α × expr × bool))
(e : expr)
(cfg : dsimp_config := {})
: tactic (α × expr)
meta def dsimplify
(pre : expr → tactic (expr × bool))
(post : expr → tactic (expr × bool))
: expr → tactic expr :=
λ e, do (a, new_e) ← dsimplify_core ()
(λ u e, do r ← pre e, return (u, r))
(λ u e, do r ← post e, return (u, r)) e,
return new_e
meta def get_simp_lemmas_or_default : option simp_lemmas → tactic simp_lemmas
| none := simp_lemmas.mk_default
| (some s) := return s
meta def dsimp_target (s : option simp_lemmas := none) (u : list name := []) (cfg : dsimp_config := {}) : tactic unit :=
do s ← get_simp_lemmas_or_default s, t ← target >>= instantiate_mvars, s.dsimplify u t cfg >>= unsafe_change
meta def dsimp_hyp (h : expr) (s : option simp_lemmas := none) (u : list name := []) (cfg : dsimp_config := {}) : tactic unit :=
do s ← get_simp_lemmas_or_default s, revert_and_transform (λ e, s.dsimplify u e cfg) h
/- Remark: we use transparency.instances by default to make sure that we
can unfold projections of type classes. Example:
(@has_add.add nat nat.has_add a b)
-/
/-- Tries to unfold `e` if it is a constant or a constant application.
Remark: this is not a recursive procedure. -/
meta constant dunfold_head (e : expr) (md := transparency.instances) : tactic expr
structure dunfold_config extends dsimp_config :=
(md := transparency.instances)
/- Remark: in principle, dunfold can be implemented on top of dsimp. We don't do it for
performance reasons. -/
meta constant dunfold (cs : list name) (e : expr) (cfg : dunfold_config := {}) : tactic expr
meta def dunfold_target (cs : list name) (cfg : dunfold_config := {}) : tactic unit :=
do t ← target, dunfold cs t cfg >>= unsafe_change
meta def dunfold_hyp (cs : list name) (h : expr) (cfg : dunfold_config := {}) : tactic unit :=
revert_and_transform (λ e, dunfold cs e cfg) h
structure delta_config :=
(max_steps := simp.default_max_steps)
(visit_instances := tt)
private meta def is_delta_target (e : expr) (cs : list name) : bool :=
cs.any (λ c,
if e.is_app_of c then tt /- Exact match -/
else let f := e.get_app_fn in
/- f is an auxiliary constant generated when compiling c -/
f.is_constant && f.const_name.is_internal && (f.const_name.get_prefix = c))
/-- Delta reduce the given constant names -/
meta def delta (cs : list name) (e : expr) (cfg : delta_config := {}) : tactic expr :=
let unfold (u : unit) (e : expr) : tactic (unit × expr × bool) := do
guard (is_delta_target e cs),
(expr.const f_name f_lvls) ← return e.get_app_fn,
env ← get_env,
decl ← env.get f_name,
new_f ← decl.instantiate_value_univ_params f_lvls,
new_e ← head_beta (expr.mk_app new_f e.get_app_args),
return (u, new_e, tt)
in do (c, new_e) ← dsimplify_core () (λ c e, failed) unfold e {max_steps := cfg.max_steps, canonize_instances := cfg.visit_instances},
return new_e
meta def delta_target (cs : list name) (cfg : delta_config := {}) : tactic unit :=
do t ← target, delta cs t cfg >>= unsafe_change
meta def delta_hyp (cs : list name) (h : expr) (cfg : delta_config := {}) :tactic unit :=
revert_and_transform (λ e, delta cs e cfg) h
structure unfold_proj_config extends dsimp_config :=
(md := transparency.instances)
/-- If `e` is a projection application, try to unfold it, otherwise fail. -/
meta constant unfold_proj (e : expr) (md := transparency.instances) : tactic expr
meta def unfold_projs (e : expr) (cfg : unfold_proj_config := {}) : tactic expr :=
let unfold (changed : bool) (e : expr) : tactic (bool × expr × bool) := do
new_e ← unfold_proj e cfg.md,
return (tt, new_e, tt)
in do (tt, new_e) ← dsimplify_core ff (λ c e, failed) unfold e cfg.to_dsimp_config | fail "no projections to unfold",
return new_e
meta def unfold_projs_target (cfg : unfold_proj_config := {}) : tactic unit :=
do t ← target, unfold_projs t cfg >>= unsafe_change
meta def unfold_projs_hyp (h : expr) (cfg : unfold_proj_config := {}) : tactic unit :=
revert_and_transform (λ e, unfold_projs e cfg) h
structure simp_config :=
(max_steps : nat := simp.default_max_steps)
(contextual : bool := ff)
(lift_eq : bool := tt)
(canonize_instances : bool := tt)
(canonize_proofs : bool := ff)
(use_axioms : bool := tt)
(zeta : bool := tt)
(beta : bool := tt)
(eta : bool := tt)
(proj : bool := tt) -- reduce projections
(iota : bool := tt)
(single_pass : bool := ff)
(fail_if_unchanged := tt)
(memoize := tt)
/--
`simplify s e cfg r prove` simplify `e` using `s` using bottom-up traversal.
`discharger` is a tactic for dischaging new subgoals created by the simplifier.
If it fails, the simplifier tries to discharge the subgoal by simplifying it to `true`.
The parameter `to_unfold` specifies definitions that should be delta-reduced,
and projection applications that should be unfolded.
-/
meta constant simplify (s : simp_lemmas) (to_unfold : list name := []) (e : expr) (cfg : simp_config := {}) (r : name := `eq)
(discharger : tactic unit := failed) : tactic (expr × expr)
meta def simp_target (s : simp_lemmas) (to_unfold : list name := []) (cfg : simp_config := {}) (discharger : tactic unit := failed) : tactic unit :=
do t ← target,
(new_t, pr) ← simplify s to_unfold t cfg `eq discharger,
replace_target new_t pr
meta def simp_hyp (s : simp_lemmas) (to_unfold : list name := []) (h : expr) (cfg : simp_config := {}) (discharger : tactic unit := failed) : tactic expr :=
do when (expr.is_local_constant h = ff) (fail "tactic simp_at failed, the given expression is not a hypothesis"),
htype ← infer_type h,
(h_new_type, pr) ← simplify s to_unfold htype cfg `eq discharger,
replace_hyp h h_new_type pr
meta constant ext_simplify_core
/- The user state type. -/
{α : Type}
/- Initial user data -/
(a : α)
(c : simp_config)
/- Congruence and simplification lemmas.
Remark: the simplification lemmas at not applied automatically like in the simplify tactic.
the caller must use them at pre/post. -/
(s : simp_lemmas)
/- Tactic for dischaging hypothesis in conditional rewriting rules.
The argument 'α' is the current user state. -/
(discharger : α → tactic α)
/- (pre a s r p e) is invoked before visiting the children of subterm 'e',
'r' is the simplification relation being used, 's' is the updated set of lemmas if 'contextual' is tt,
'p' is the "parent" expression (if there is one).
if it succeeds the result is (new_a, new_e, new_pr, flag) where
- 'new_a' is the new value for the user data
- 'new_e' is a new expression s.t. 'e r new_e'
- 'new_pr' is a proof for 'e r new_e', If it is none, the proof is assumed to be by reflexivity
- 'flag' if tt 'new_e' children should be visited, and 'post' invoked. -/
(pre : α → simp_lemmas → name → option expr → expr → tactic (α × expr × option expr × bool))
/- (post a s r p e) is invoked after visiting the children of subterm 'e',
The output is similar to (pre a r s p e), but the 'flag' indicates whether
the new expression should be revisited or not. -/
(post : α → simp_lemmas → name → option expr → expr → tactic (α × expr × option expr × bool))
/- simplification relation -/
(r : name) :
expr → tactic (α × expr × expr)
private meta def is_equation : expr → bool
| (expr.pi n bi d b) := is_equation b
| e := match (expr.is_eq e) with (some a) := tt | none := ff end
meta def collect_ctx_simps : tactic (list expr) :=
local_context
section simp_intros
meta def intro1_aux : bool → list name → tactic expr
| ff _ := intro1
| tt (n::ns) := intro n
| _ _ := failed
structure simp_intros_config extends simp_config :=
(use_hyps := ff)
meta def simp_intros_aux (cfg : simp_config) (use_hyps : bool) (to_unfold : list name) : simp_lemmas → bool → list name → tactic simp_lemmas
| S tt [] := try (simp_target S to_unfold cfg) >> return S
| S use_ns ns := do
t ← target,
if t.is_napp_of `not 1 then
intro1_aux use_ns ns >> simp_intros_aux S use_ns ns.tail
else if t.is_arrow then
do {
d ← return t.binding_domain,
(new_d, h_d_eq_new_d) ← simplify S to_unfold d cfg,
h_d ← intro1_aux use_ns ns,
h_new_d ← mk_eq_mp h_d_eq_new_d h_d,
assertv_core h_d.local_pp_name new_d h_new_d,
clear h_d,
h_new ← intro1,
new_S ← if use_hyps then mcond (is_prop new_d) (S.add h_new) (return S)
else return S,
simp_intros_aux new_S use_ns ns.tail
}
<|>
-- failed to simplify... we just introduce and continue
(intro1_aux use_ns ns >> simp_intros_aux S use_ns ns.tail)
else if t.is_pi || t.is_let then
intro1_aux use_ns ns >> simp_intros_aux S use_ns ns.tail
else do
new_t ← whnf t reducible,
if new_t.is_pi then unsafe_change new_t >> simp_intros_aux S use_ns ns
else
try (simp_target S to_unfold cfg) >>
mcond (expr.is_pi <$> target)
(simp_intros_aux S use_ns ns)
(if use_ns ∧ ¬ns.empty then failed else return S)
meta def simp_intros (s : simp_lemmas) (to_unfold : list name := []) (ids : list name := []) (cfg : simp_intros_config := {}) : tactic unit :=
step $ simp_intros_aux cfg.to_simp_config cfg.use_hyps to_unfold s (bnot ids.empty) ids
end simp_intros
meta def mk_eq_simp_ext (simp_ext : expr → tactic (expr × expr)) : tactic unit :=
do (lhs, rhs) ← target >>= match_eq,
(new_rhs, heq) ← simp_ext lhs,
unify rhs new_rhs,
exact heq
/- Simp attribute support -/
meta def to_simp_lemmas : simp_lemmas → list name → tactic simp_lemmas
| S [] := return S
| S (n::ns) := do S' ← S.add_simp n, to_simp_lemmas S' ns
meta def mk_simp_attr (attr_name : name) : command :=
do let t := `(caching_user_attribute simp_lemmas),
let v := `({name := attr_name,
descr := "simplifier attribute",
mk_cache := λ ns, do {tactic.to_simp_lemmas simp_lemmas.mk ns},
dependencies := [`reducibility] } : caching_user_attribute simp_lemmas),
add_decl (declaration.defn attr_name [] t v reducibility_hints.abbrev ff),
attribute.register attr_name
meta def get_user_simp_lemmas (attr_name : name) : tactic simp_lemmas :=
if attr_name = `default then simp_lemmas.mk_default
else do
cnst ← return (expr.const attr_name []),
attr ← eval_expr (caching_user_attribute simp_lemmas) cnst,
caching_user_attribute.get_cache attr
meta def join_user_simp_lemmas_core : simp_lemmas → list name → tactic simp_lemmas
| S [] := return S
| S (attr_name::R) := do S' ← get_user_simp_lemmas attr_name, join_user_simp_lemmas_core (S.join S') R
meta def join_user_simp_lemmas (no_dflt : bool) (attrs : list name) : tactic simp_lemmas :=
if no_dflt then
join_user_simp_lemmas_core simp_lemmas.mk attrs
else do
s ← simp_lemmas.mk_default,
join_user_simp_lemmas_core s attrs
/-- Normalize numerical expression, returns a pair (n, pr) where n is the resultant numeral,
and pr is a proof that the input argument is equal to n. -/
meta constant norm_num : expr → tactic (expr × expr)
meta def simplify_top_down {α} (a : α) (pre : α → expr → tactic (α × expr × expr)) (e : expr) (cfg : simp_config := {}) : tactic (α × expr × expr) :=
ext_simplify_core a cfg simp_lemmas.mk (λ _, failed)
(λ a _ _ _ e, do (new_a, new_e, pr) ← pre a e, guard (¬ new_e =ₐ e), return (new_a, new_e, some pr, tt))
(λ _ _ _ _ _, failed)
`eq e
meta def simp_top_down (pre : expr → tactic (expr × expr)) (cfg : simp_config := {}) : tactic unit :=
do t ← target,
(_, new_target, pr) ← simplify_top_down () (λ _ e, do (new_e, pr) ← pre e, return ((), new_e, pr)) t cfg,
replace_target new_target pr
meta def simplify_bottom_up {α} (a : α) (post : α → expr → tactic (α × expr × expr)) (e : expr) (cfg : simp_config := {}) : tactic (α × expr × expr) :=
ext_simplify_core a cfg simp_lemmas.mk (λ _, failed)
(λ _ _ _ _ _, failed)
(λ a _ _ _ e, do (new_a, new_e, pr) ← post a e, guard (¬ new_e =ₐ e), return (new_a, new_e, some pr, tt))
`eq e
meta def simp_bottom_up (post : expr → tactic (expr × expr)) (cfg : simp_config := {}) : tactic unit :=
do t ← target,
(_, new_target, pr) ← simplify_bottom_up () (λ _ e, do (new_e, pr) ← post e, return ((), new_e, pr)) t cfg,
replace_target new_target pr
private meta def remove_deps (s : name_set) (h : expr) : name_set :=
if s.empty then s
else h.fold s (λ e o s, if e.is_local_constant then s.erase e.local_uniq_name else s)
/- Return the list of hypothesis that are propositions and do not have
forward dependencies. -/
meta def non_dep_prop_hyps : tactic (list expr) :=
do
ctx ← local_context,
s ← ctx.mfoldl (λ s h, do
h_type ← infer_type h,
let s := remove_deps s h_type,
h_val ← head_zeta h,
let s := if h_val =ₐ h then s else remove_deps s h_val,
mcond (is_prop h_type)
(return $ s.insert h.local_uniq_name)
(return s)) mk_name_set,
t ← target,
let s := remove_deps s t,
return $ ctx.filter (λ h, s.contains h.local_uniq_name)
section simp_all
meta structure simp_all_entry :=
(h : expr) -- hypothesis
(new_type : expr) -- new type
(pr : option expr) -- proof that type of h is equal to new_type
(s : simp_lemmas) -- simplification lemmas for simplifying new_type
private meta def update_simp_lemmas (es : list simp_all_entry) (h : expr) : tactic (list simp_all_entry) :=
es.mmap $ λ e, do new_s ← e.s.add h, return {e with s := new_s}
/- Helper tactic for `init`.
Remark: the following tactic is quadratic on the length of list expr (the list of non dependent propositions).
We can make it more efficient as soon as we have an efficient simp_lemmas.erase. -/
private meta def init_aux : list expr → simp_lemmas → list simp_all_entry → tactic (simp_lemmas × list simp_all_entry)
| [] s r := return (s, r)
| (h::hs) s r := do
new_r ← update_simp_lemmas r h,
new_s ← s.add h,
h_type ← infer_type h,
init_aux hs new_s (⟨h, h_type, none, s⟩::new_r)
private meta def init (s : simp_lemmas) (hs : list expr) : tactic (simp_lemmas × list simp_all_entry) :=
init_aux hs s []
private meta def add_new_hyps (es : list simp_all_entry) : tactic unit :=
es.mmap' $ λ e,
match e.pr with
| none := return ()
| some pr :=
assert e.h.local_pp_name e.new_type >>
mk_eq_mp pr e.h >>= exact
end
private meta def clear_old_hyps (es : list simp_all_entry) : tactic unit :=
es.mmap' $ λ e, when (e.pr ≠ none) (try (clear e.h))
private meta def join_pr : option expr → expr → tactic expr
| none pr₂ := return pr₂
| (some pr₁) pr₂ := mk_eq_trans pr₁ pr₂
private meta def loop (cfg : simp_config) (discharger : tactic unit) (to_unfold : list name)
: list simp_all_entry → list simp_all_entry → simp_lemmas → bool → tactic unit
| [] r s m :=
if m then loop r [] s ff
else do
add_new_hyps r,
target_changed ← (simp_target s to_unfold cfg discharger >> return tt) <|> return ff,
guard (cfg.fail_if_unchanged = ff ∨ target_changed ∨ r.any (λ e, e.pr ≠ none)) <|> fail "simp_all tactic failed to simplify",
clear_old_hyps r
| (e::es) r s m := do
let ⟨h, h_type, h_pr, s'⟩ := e,
(new_h_type, new_pr) ← simplify s' to_unfold h_type {cfg with fail_if_unchanged := ff} `eq discharger,
if h_type =ₐ new_h_type then loop es (e::r) s m
else do
new_pr ← join_pr h_pr new_pr,
new_fact_pr ← mk_eq_mp new_pr h,
if new_h_type = `(false) then do
tgt ← target,
to_expr ``(@false.rec %%tgt %%new_fact_pr) >>= exact
else do
h0_type ← infer_type h,
let new_fact_pr := mk_id_locked_proof new_h_type new_fact_pr,
new_es ← update_simp_lemmas es new_fact_pr,
new_r ← update_simp_lemmas r new_fact_pr,
let new_r := {e with new_type := new_h_type, pr := new_pr} :: new_r,
new_s ← s.add new_fact_pr,
loop new_es new_r new_s tt
meta def simp_all (s : simp_lemmas) (to_unfold : list name) (cfg : simp_config := {}) (discharger : tactic unit := failed) : tactic unit :=
do hs ← non_dep_prop_hyps,
(s, es) ← init s hs,
loop cfg discharger to_unfold es [] s ff
end simp_all
/- debugging support for algebraic normalizer -/
meta constant trace_algebra_info : expr → tactic unit
end tactic
export tactic (mk_simp_attr)
|
ea8bc109ddbf9fe13ffac0e1b16b9da24947152c | bb31430994044506fa42fd667e2d556327e18dfe | /src/topology/instances/add_circle.lean | a67ddcb2eb9823369b90da178b3903afd552900d | [
"Apache-2.0"
] | permissive | sgouezel/mathlib | 0cb4e5335a2ba189fa7af96d83a377f83270e503 | 00638177efd1b2534fc5269363ebf42a7871df9a | refs/heads/master | 1,674,527,483,042 | 1,673,665,568,000 | 1,673,665,568,000 | 119,598,202 | 0 | 0 | null | 1,517,348,647,000 | 1,517,348,646,000 | null | UTF-8 | Lean | false | false | 23,983 | lean | /-
Copyright (c) 2022 Oliver Nash. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Oliver Nash
-/
import data.nat.totient
import algebra.ring.add_aut
import group_theory.divisible
import group_theory.order_of_element
import ring_theory.int.basic
import algebra.order.floor
import algebra.order.to_interval_mod
import topology.instances.real
/-!
# The additive circle
We define the additive circle `add_circle p` as the quotient `𝕜 ⧸ (ℤ ∙ p)` for some period `p : 𝕜`.
See also `circle` and `real.angle`. For the normed group structure on `add_circle`, see
`add_circle.normed_add_comm_group` in a later file.
## Main definitions and results:
* `add_circle`: the additive circle `𝕜 ⧸ (ℤ ∙ p)` for some period `p : 𝕜`
* `unit_add_circle`: the special case `ℝ ⧸ ℤ`
* `add_circle.equiv_add_circle`: the rescaling equivalence `add_circle p ≃+ add_circle q`
* `add_circle.equiv_Ico`: the natural equivalence `add_circle p ≃ Ico a (a + p)`
* `add_circle.add_order_of_div_of_gcd_eq_one`: rational points have finite order
* `add_circle.exists_gcd_eq_one_of_is_of_fin_add_order`: finite-order points are rational
* `add_circle.homeo_Icc_quot`: the natural topological equivalence between `add_circle p` and
`Icc a (a + p)` with its endpoints identified.
* `add_circle.lift_Ico_continuous`: if `f : ℝ → B` is continuous, and `f a = f (a + p)` for
some `a`, then there is a continuous function `add_circle p → B` which agrees with `f` on
`Icc a (a + p)`.
## Implementation notes:
Although the most important case is `𝕜 = ℝ` we wish to support other types of scalars, such as
the rational circle `add_circle (1 : ℚ)`, and so we set things up more generally.
## TODO
* Link with periodicity
* Lie group structure
* Exponential equivalence to `circle`
-/
noncomputable theory
open set function add_subgroup topological_space
open_locale topological_space
variables {𝕜 B : Type*}
section continuity
variables [linear_ordered_add_comm_group 𝕜] [archimedean 𝕜]
[topological_space 𝕜] [order_topology 𝕜] (a : 𝕜) {p : 𝕜} (hp : 0 < p) (x : 𝕜)
lemma continuous_right_to_Ico_mod : continuous_within_at (to_Ico_mod a hp) (Ici x) x :=
begin
intros s h,
rw [filter.mem_map, mem_nhds_within_iff_exists_mem_nhds_inter],
haveI : nontrivial 𝕜 := ⟨⟨0, p, hp.ne⟩⟩,
simp_rw mem_nhds_iff_exists_Ioo_subset at h ⊢,
obtain ⟨l, u, hxI, hIs⟩ := h,
let d := to_Ico_div a hp x • p,
have hd := to_Ico_mod_mem_Ico a hp x,
simp_rw [subset_def, mem_inter_iff],
refine ⟨_, ⟨l - d, min (a + p) u - d, _, λ x, id⟩, λ y, _⟩;
simp_rw [← add_mem_Ioo_iff_left, mem_Ioo, lt_min_iff],
{ exact ⟨hxI.1, hd.2, hxI.2⟩ },
{ rintro ⟨h, h'⟩, apply hIs,
rw [← to_Ico_mod_add_zsmul, (to_Ico_mod_eq_self _).2],
exacts [⟨h.1, h.2.2⟩, ⟨hd.1.trans (add_le_add_right h' _), h.2.1⟩] },
end
lemma continuous_left_to_Ioc_mod : continuous_within_at (to_Ioc_mod a hp) (Iic x) x :=
begin
rw (funext (λ y, eq.trans (by rw neg_neg) $ to_Ioc_mod_neg _ _ _) :
to_Ioc_mod a hp = (λ x, p - x) ∘ to_Ico_mod (-a) hp ∘ has_neg.neg),
exact ((continuous_sub_left _).continuous_at.comp_continuous_within_at $
(continuous_right_to_Ico_mod _ _ _).comp continuous_neg.continuous_within_at $ λ y, neg_le_neg),
end
variables {x} (hx : (x : 𝕜 ⧸ zmultiples p) ≠ a)
lemma to_Ico_mod_eventually_eq_to_Ioc_mod : to_Ico_mod a hp =ᶠ[𝓝 x] to_Ioc_mod a hp :=
is_open.mem_nhds (by {rw Ico_eq_locus_Ioc_eq_Union_Ioo, exact is_open_Union (λ i, is_open_Ioo)}) $
(mem_Ioo_mod_iff_to_Ico_mod_eq_to_Ioc_mod hp).1 ((mem_Ioo_mod_iff_eq_mod_zmultiples hp).2 hx)
lemma continuous_at_to_Ico_mod : continuous_at (to_Ico_mod a hp) x :=
let h := to_Ico_mod_eventually_eq_to_Ioc_mod a hp hx in continuous_at_iff_continuous_left_right.2 $
⟨(continuous_left_to_Ioc_mod a hp x).congr_of_eventually_eq
(h.filter_mono nhds_within_le_nhds) h.eq_of_nhds, continuous_right_to_Ico_mod a hp x⟩
lemma continuous_at_to_Ioc_mod : continuous_at (to_Ioc_mod a hp) x :=
let h := to_Ico_mod_eventually_eq_to_Ioc_mod a hp hx in continuous_at_iff_continuous_left_right.2 $
⟨continuous_left_to_Ioc_mod a hp x, (continuous_right_to_Ico_mod a hp x).congr_of_eventually_eq
(h.symm.filter_mono nhds_within_le_nhds) h.symm.eq_of_nhds⟩
end continuity
/-- The "additive circle": `𝕜 ⧸ (ℤ ∙ p)`. See also `circle` and `real.angle`. -/
@[derive [add_comm_group, topological_space, topological_add_group, inhabited, has_coe_t 𝕜],
nolint unused_arguments]
def add_circle [linear_ordered_add_comm_group 𝕜] [topological_space 𝕜] [order_topology 𝕜] (p : 𝕜) :=
𝕜 ⧸ zmultiples p
namespace add_circle
section linear_ordered_add_comm_group
variables [linear_ordered_add_comm_group 𝕜] [topological_space 𝕜] [order_topology 𝕜] (p : 𝕜)
lemma coe_nsmul {n : ℕ} {x : 𝕜} : (↑(n • x) : add_circle p) = n • (x : add_circle p) := rfl
lemma coe_zsmul {n : ℤ} {x : 𝕜} : (↑(n • x) : add_circle p) = n • (x : add_circle p) := rfl
lemma coe_add (x y : 𝕜) : (↑(x + y) : add_circle p) = (x : add_circle p) + (y : add_circle p) := rfl
lemma coe_sub (x y : 𝕜) : (↑(x - y) : add_circle p) = (x : add_circle p) - (y : add_circle p) := rfl
lemma coe_neg {x : 𝕜} : (↑(-x) : add_circle p) = -(x : add_circle p) := rfl
lemma coe_eq_zero_iff {x : 𝕜} : (x : add_circle p) = 0 ↔ ∃ (n : ℤ), n • p = x :=
by simp [add_subgroup.mem_zmultiples_iff]
lemma coe_eq_zero_of_pos_iff (hp : 0 < p) {x : 𝕜} (hx : 0 < x) :
(x : add_circle p) = 0 ↔ ∃ (n : ℕ), n • p = x :=
begin
rw coe_eq_zero_iff,
split;
rintros ⟨n, rfl⟩,
{ replace hx : 0 < n,
{ contrapose! hx,
simpa only [←neg_nonneg, ←zsmul_neg, zsmul_neg'] using zsmul_nonneg hp.le (neg_nonneg.2 hx) },
exact ⟨n.to_nat, by rw [← coe_nat_zsmul, int.to_nat_of_nonneg hx.le]⟩, },
{ exact ⟨(n : ℤ), by simp⟩, },
end
lemma coe_period : (p : add_circle p) = 0 :=
(quotient_add_group.eq_zero_iff p).2 $ mem_zmultiples p
@[simp] lemma coe_add_period (x : 𝕜) : ((x + p : 𝕜) : add_circle p) = x :=
by rw [coe_add, ←eq_sub_iff_add_eq', sub_self, coe_period]
@[continuity, nolint unused_arguments] protected lemma continuous_mk' :
continuous (quotient_add_group.mk' (zmultiples p) : 𝕜 → add_circle p) :=
continuous_coinduced_rng
variables [hp : fact (0 < p)]
include hp
variables (a : 𝕜) [archimedean 𝕜]
/-- The equivalence between `add_circle p` and the half-open interval `[a, a + p)`, whose inverse
is the natural quotient map. -/
def equiv_Ico : add_circle p ≃ Ico a (a + p) := quotient_add_group.equiv_Ico_mod a hp.out
/-- The equivalence between `add_circle p` and the half-open interval `(a, a + p]`, whose inverse
is the natural quotient map. -/
def equiv_Ioc : add_circle p ≃ Ioc a (a + p) := quotient_add_group.equiv_Ioc_mod a hp.out
/-- Given a function on `𝕜`, return the unique function on `add_circle p` agreeing with `f` on
`[a, a + p)`. -/
def lift_Ico (f : 𝕜 → B) : add_circle p → B := restrict _ f ∘ add_circle.equiv_Ico p a
/-- Given a function on `𝕜`, return the unique function on `add_circle p` agreeing with `f` on
`(a, a + p]`. -/
def lift_Ioc (f : 𝕜 → B) : add_circle p → B := restrict _ f ∘ add_circle.equiv_Ioc p a
variables {p a}
lemma coe_eq_coe_iff_of_mem_Ico {x y : 𝕜}
(hx : x ∈ Ico a (a + p)) (hy : y ∈ Ico a (a + p)) : (x : add_circle p) = y ↔ x = y :=
begin
refine ⟨λ h, _, by tauto⟩,
suffices : (⟨x, hx⟩ : Ico a (a + p)) = ⟨y, hy⟩, by exact subtype.mk.inj this,
apply_fun equiv_Ico p a at h,
rw [←(equiv_Ico p a).right_inv ⟨x, hx⟩, ←(equiv_Ico p a).right_inv ⟨y, hy⟩],
exact h
end
lemma lift_Ico_coe_apply {f : 𝕜 → B} {x : 𝕜} (hx : x ∈ Ico a (a + p)) : lift_Ico p a f ↑x = f x :=
begin
have : (equiv_Ico p a) x = ⟨x, hx⟩,
{ rw equiv.apply_eq_iff_eq_symm_apply,
refl, },
rw [lift_Ico, comp_apply, this],
refl,
end
lemma lift_Ioc_coe_apply {f : 𝕜 → B} {x : 𝕜} (hx : x ∈ Ioc a (a + p)) : lift_Ioc p a f ↑x = f x :=
begin
have : (equiv_Ioc p a) x = ⟨x, hx⟩,
{ rw equiv.apply_eq_iff_eq_symm_apply,
refl, },
rw [lift_Ioc, comp_apply, this],
refl,
end
variables (p a)
section continuity
@[continuity] lemma continuous_equiv_Ico_symm : continuous (equiv_Ico p a).symm :=
continuous_quotient_mk.comp continuous_subtype_coe
@[continuity] lemma continuous_equiv_Ioc_symm : continuous (equiv_Ioc p a).symm :=
continuous_quotient_mk.comp continuous_subtype_coe
variables {x : add_circle p} (hx : x ≠ a)
include hx
lemma continuous_at_equiv_Ico : continuous_at (equiv_Ico p a) x :=
begin
induction x using quotient_add_group.induction_on',
rw [continuous_at, filter.tendsto, quotient_add_group.nhds_eq, filter.map_map],
apply continuous_at.cod_restrict, exact continuous_at_to_Ico_mod a hp.out hx,
end
lemma continuous_at_equiv_Ioc : continuous_at (equiv_Ioc p a) x :=
begin
induction x using quotient_add_group.induction_on',
rw [continuous_at, filter.tendsto, quotient_add_group.nhds_eq, filter.map_map],
apply continuous_at.cod_restrict, exact continuous_at_to_Ioc_mod a hp.out hx,
end
end continuity
/-- The image of the closed-open interval `[a, a + p)` under the quotient map `𝕜 → add_circle p` is
the entire space. -/
@[simp] lemma coe_image_Ico_eq : (coe : 𝕜 → add_circle p) '' Ico a (a + p) = univ :=
by { rw image_eq_range, exact (equiv_Ico p a).symm.range_eq_univ }
/-- The image of the closed-open interval `[a, a + p)` under the quotient map `𝕜 → add_circle p` is
the entire space. -/
@[simp] lemma coe_image_Ioc_eq : (coe : 𝕜 → add_circle p) '' Ioc a (a + p) = univ :=
by { rw image_eq_range, exact (equiv_Ioc p a).symm.range_eq_univ }
/-- The image of the closed interval `[0, p]` under the quotient map `𝕜 → add_circle p` is the
entire space. -/
@[simp] lemma coe_image_Icc_eq : (coe : 𝕜 → add_circle p) '' Icc a (a + p) = univ :=
eq_top_mono (image_subset _ Ico_subset_Icc_self) $ coe_image_Ico_eq _ _
end linear_ordered_add_comm_group
section linear_ordered_field
variables [linear_ordered_field 𝕜] [topological_space 𝕜] [order_topology 𝕜] (p q : 𝕜)
/-- The rescaling equivalence between additive circles with different periods. -/
def equiv_add_circle (hp : p ≠ 0) (hq : q ≠ 0) : add_circle p ≃+ add_circle q :=
quotient_add_group.congr _ _ (add_aut.mul_right $ (units.mk0 p hp)⁻¹ * units.mk0 q hq) $
by rw [add_monoid_hom.map_zmultiples, add_monoid_hom.coe_coe, add_aut.mul_right_apply,
units.coe_mul, units.coe_mk0, units.coe_inv, units.coe_mk0, mul_inv_cancel_left₀ hp]
@[simp] lemma equiv_add_circle_apply_mk (hp : p ≠ 0) (hq : q ≠ 0) (x : 𝕜) :
equiv_add_circle p q hp hq (x : 𝕜) = (x * (p⁻¹ * q) : 𝕜) :=
rfl
@[simp] lemma equiv_add_circle_symm_apply_mk (hp : p ≠ 0) (hq : q ≠ 0) (x : 𝕜) :
(equiv_add_circle p q hp hq).symm (x : 𝕜) = (x * (q⁻¹ * p) : 𝕜) :=
rfl
variables [hp : fact (0 < p)]
include hp
section floor_ring
variables [floor_ring 𝕜]
@[simp] lemma coe_equiv_Ico_mk_apply (x : 𝕜) :
(equiv_Ico p 0 $ quotient_add_group.mk x : 𝕜) = int.fract (x / p) * p :=
to_Ico_mod_eq_fract_mul _ x
instance : divisible_by (add_circle p) ℤ :=
{ div := λ x n, (↑(((n : 𝕜)⁻¹) * (equiv_Ico p 0 x : 𝕜)) : add_circle p),
div_zero := λ x,
by simp only [algebra_map.coe_zero, quotient_add_group.coe_zero, inv_zero, zero_mul],
div_cancel := λ n x hn,
begin
replace hn : (n : 𝕜) ≠ 0, { norm_cast, assumption, },
change n • quotient_add_group.mk' _ ((n : 𝕜)⁻¹ * ↑(equiv_Ico p 0 x)) = x,
rw [← map_zsmul, ← smul_mul_assoc, zsmul_eq_mul, mul_inv_cancel hn, one_mul],
exact (equiv_Ico p 0).symm_apply_apply x,
end, }
end floor_ring
section finite_order_points
variables {p}
lemma add_order_of_period_div {n : ℕ} (h : 0 < n) : add_order_of ((p / n : 𝕜) : add_circle p) = n :=
begin
rw [add_order_of_eq_iff h],
replace h : 0 < (n : 𝕜) := nat.cast_pos.2 h,
refine ⟨_, λ m hn h0, _⟩; simp only [ne, ← coe_nsmul, nsmul_eq_mul],
{ rw [mul_div_cancel' _ h.ne', coe_period] },
rw coe_eq_zero_of_pos_iff p hp.out (mul_pos (nat.cast_pos.2 h0) $ div_pos hp.out h),
rintro ⟨k, hk⟩,
rw [mul_div, eq_div_iff h.ne', nsmul_eq_mul, mul_right_comm, ← nat.cast_mul,
(mul_left_injective₀ hp.out.ne').eq_iff, nat.cast_inj, mul_comm] at hk,
exact (nat.le_of_dvd h0 ⟨_, hk.symm⟩).not_lt hn,
end
variables (p)
lemma gcd_mul_add_order_of_div_eq {n : ℕ} (m : ℕ) (hn : 0 < n) :
m.gcd n * add_order_of (↑(↑m / ↑n * p) : add_circle p) = n :=
begin
rw [mul_comm_div, ← nsmul_eq_mul, coe_nsmul, add_order_of_nsmul''],
{ rw [add_order_of_period_div hn, nat.gcd_comm, nat.mul_div_cancel'],
exacts [n.gcd_dvd_left m, hp] },
{ rw [← add_order_of_pos_iff, add_order_of_period_div hn], exacts [hn, hp] },
end
variable {p}
lemma add_order_of_div_of_gcd_eq_one {m n : ℕ} (hn : 0 < n) (h : m.gcd n = 1) :
add_order_of (↑(↑m / ↑n * p) : add_circle p) = n :=
by { convert gcd_mul_add_order_of_div_eq p m hn, rw [h, one_mul] }
lemma add_order_of_div_of_gcd_eq_one' {m : ℤ} {n : ℕ} (hn : 0 < n) (h : m.nat_abs.gcd n = 1) :
add_order_of (↑(↑m / ↑n * p) : add_circle p) = n :=
begin
induction m,
{ simp only [int.of_nat_eq_coe, int.cast_coe_nat, int.nat_abs_of_nat] at h ⊢,
exact add_order_of_div_of_gcd_eq_one hn h, },
{ simp only [int.cast_neg_succ_of_nat, neg_div, neg_mul, coe_neg, order_of_neg],
exact add_order_of_div_of_gcd_eq_one hn h, },
end
lemma add_order_of_coe_rat {q : ℚ} : add_order_of (↑(↑q * p) : add_circle p) = q.denom :=
begin
have : (↑(q.denom : ℤ) : 𝕜) ≠ 0, { norm_cast, exact q.pos.ne.symm, },
rw [← @rat.num_denom q, rat.cast_mk_of_ne_zero _ _ this, int.cast_coe_nat, rat.num_denom,
add_order_of_div_of_gcd_eq_one' q.pos q.cop],
apply_instance,
end
lemma add_order_of_eq_pos_iff {u : add_circle p} {n : ℕ} (h : 0 < n) :
add_order_of u = n ↔ ∃ m < n, m.gcd n = 1 ∧ ↑(↑m / ↑n * p) = u :=
begin
refine ⟨quotient_add_group.induction_on' u (λ k hk, _), _⟩, swap,
{ rintros ⟨m, h₀, h₁, rfl⟩, exact add_order_of_div_of_gcd_eq_one h h₁ },
have h0 := add_order_of_nsmul_eq_zero (k : add_circle p),
rw [hk, ← coe_nsmul, coe_eq_zero_iff] at h0,
obtain ⟨a, ha⟩ := h0,
have h0 : (_ : 𝕜) ≠ 0 := nat.cast_ne_zero.2 h.ne',
rw [nsmul_eq_mul, mul_comm, ← div_eq_iff h0, ← a.div_add_mod' n, add_smul, add_div, zsmul_eq_mul,
int.cast_mul, int.cast_coe_nat, mul_assoc, ← mul_div, mul_comm _ p, mul_div_cancel p h0] at ha,
have han : _ = a % n := int.to_nat_of_nonneg (int.mod_nonneg _ $ by exact_mod_cast h.ne'),
have he := _, refine ⟨(a % n).to_nat, _, _, he⟩,
{ rw [← int.coe_nat_lt, han],
exact int.mod_lt_of_pos _ (int.coe_nat_lt.2 h) },
{ have := (gcd_mul_add_order_of_div_eq p _ h).trans ((congr_arg add_order_of he).trans hk).symm,
rw [he, nat.mul_left_eq_self_iff] at this, { exact this }, { rwa hk } },
convert congr_arg coe ha using 1,
rw [coe_add, ← int.cast_coe_nat, han, zsmul_eq_mul, mul_div_right_comm,
eq_comm, add_left_eq_self, ← zsmul_eq_mul, coe_zsmul, coe_period, smul_zero],
end
lemma exists_gcd_eq_one_of_is_of_fin_add_order {u : add_circle p} (h : is_of_fin_add_order u) :
∃ m : ℕ, m.gcd (add_order_of u) = 1 ∧
m < (add_order_of u) ∧
↑(((m : 𝕜) / add_order_of u) * p) = u :=
let ⟨m, hl, hg, he⟩ := (add_order_of_eq_pos_iff $ add_order_of_pos' h).1 rfl in ⟨m, hg, hl, he⟩
variables (p)
/-- The natural bijection between points of order `n` and natural numbers less than and coprime to
`n`. The inverse of the map sends `m ↦ (m/n * p : add_circle p)` where `m` is coprime to `n` and
satisfies `0 ≤ m < n`. -/
def set_add_order_of_equiv {n : ℕ} (hn : 0 < n) :
{u : add_circle p | add_order_of u = n} ≃ {m | m < n ∧ m.gcd n = 1} :=
equiv.symm $ equiv.of_bijective
(λ m, ⟨↑((m : 𝕜) / n * p), add_order_of_div_of_gcd_eq_one hn (m.prop.2)⟩)
begin
refine ⟨λ m₁ m₂ h, subtype.ext _, λ u, _⟩,
{ simp_rw [subtype.ext_iff, subtype.coe_mk] at h,
rw [← sub_eq_zero, ← coe_sub, ← sub_mul, ← sub_div, coe_coe, coe_coe, ← int.cast_coe_nat m₁,
← int.cast_coe_nat m₂, ← int.cast_sub, coe_eq_zero_iff] at h,
obtain ⟨m, hm⟩ := h,
rw [← mul_div_right_comm, eq_div_iff, mul_comm, ← zsmul_eq_mul, mul_smul_comm, ← nsmul_eq_mul,
← coe_nat_zsmul, smul_smul, (zsmul_strict_mono_left hp.out).injective.eq_iff, mul_comm] at hm,
swap, { exact nat.cast_ne_zero.2 hn.ne' },
rw [← @nat.cast_inj ℤ, ← sub_eq_zero],
refine int.eq_zero_of_abs_lt_dvd ⟨_, hm.symm⟩ (abs_sub_lt_iff.2 ⟨_, _⟩);
apply (int.sub_le_self _ $ nat.cast_nonneg _).trans_lt (nat.cast_lt.2 _),
exacts [m₁.2.1, m₂.2.1] },
obtain ⟨m, hmn, hg, he⟩ := (add_order_of_eq_pos_iff hn).mp u.2,
exact ⟨⟨m, hmn, hg⟩, subtype.ext he⟩,
end
@[simp] lemma card_add_order_of_eq_totient {n : ℕ} :
nat.card {u : add_circle p // add_order_of u = n} = n.totient :=
begin
rcases n.eq_zero_or_pos with rfl | hn,
{ simp only [nat.totient_zero, add_order_of_eq_zero_iff],
rcases em (∃ (u : add_circle p), ¬ is_of_fin_add_order u) with ⟨u, hu⟩ | h,
{ haveI : infinite {u : add_circle p // ¬is_of_fin_add_order u},
{ erw infinite_coe_iff,
exact infinite_not_is_of_fin_add_order hu, },
exact nat.card_eq_zero_of_infinite, },
{ haveI : is_empty {u : add_circle p // ¬is_of_fin_add_order u}, { simpa using h, },
exact nat.card_of_is_empty, }, },
{ rw [← coe_set_of, nat.card_congr (set_add_order_of_equiv p hn),
n.totient_eq_card_lt_and_coprime],
simp only [nat.gcd_comm], },
end
lemma finite_set_of_add_order_eq {n : ℕ} (hn : 0 < n) :
{u : add_circle p | add_order_of u = n}.finite :=
finite_coe_iff.mp $ nat.finite_of_card_ne_zero $ by simpa only [coe_set_of,
card_add_order_of_eq_totient p] using (nat.totient_pos hn).ne'
end finite_order_points
end linear_ordered_field
variables (p : ℝ)
/-- The "additive circle" `ℝ ⧸ (ℤ ∙ p)` is compact. -/
instance compact_space [fact (0 < p)] : compact_space $ add_circle p :=
begin
rw [← is_compact_univ_iff, ← coe_image_Icc_eq p 0],
exact is_compact_Icc.image (add_circle.continuous_mk' p),
end
/-- The action on `ℝ` by right multiplication of its the subgroup `zmultiples p` (the multiples of
`p:ℝ`) is properly discontinuous. -/
instance : properly_discontinuous_vadd (zmultiples p).opposite ℝ :=
(zmultiples p).properly_discontinuous_vadd_opposite_of_tendsto_cofinite
(add_subgroup.tendsto_zmultiples_subtype_cofinite p)
/-- The "additive circle" `ℝ ⧸ (ℤ ∙ p)` is Hausdorff. -/
instance : t2_space (add_circle p) := t2_space_of_properly_discontinuous_vadd_of_t2_space
/-- The "additive circle" `ℝ ⧸ (ℤ ∙ p)` is normal. -/
instance [fact (0 < p)] : normal_space (add_circle p) := normal_of_compact_t2
/-- The "additive circle" `ℝ ⧸ (ℤ ∙ p)` is second-countable. -/
instance : second_countable_topology (add_circle p) := quotient_add_group.second_countable_topology
end add_circle
local attribute [instance] real.fact_zero_lt_one
/-- The unit circle `ℝ ⧸ ℤ`. -/
@[derive [compact_space, normal_space, second_countable_topology]]
abbreviation unit_add_circle := add_circle (1 : ℝ)
section identify_Icc_ends
/-! This section proves that for any `a`, the natural map from `[a, a + p] ⊂ 𝕜` to `add_circle p`
gives an identification of `add_circle p`, as a topological space, with the quotient of `[a, a + p]`
by the equivalence relation identifying the endpoints. -/
namespace add_circle
variables [linear_ordered_add_comm_group 𝕜] [topological_space 𝕜] [order_topology 𝕜]
(p a : 𝕜) [hp : fact (0 < p)]
include hp
local notation `𝕋` := add_circle p
/-- The relation identifying the endpoints of `Icc a (a + p)`. -/
inductive endpoint_ident : Icc a (a + p) → Icc a (a + p) → Prop
| mk : endpoint_ident
⟨a, left_mem_Icc.mpr $ le_add_of_nonneg_right hp.out.le⟩
⟨a + p, right_mem_Icc.mpr $ le_add_of_nonneg_right hp.out.le⟩
variables [archimedean 𝕜]
/-- The equivalence between `add_circle p` and the quotient of `[a, a + p]` by the relation
identifying the endpoints. -/
def equiv_Icc_quot : 𝕋 ≃ quot (endpoint_ident p a) :=
{ to_fun := λ x, quot.mk _ $ inclusion Ico_subset_Icc_self (equiv_Ico _ _ x),
inv_fun := λ x, quot.lift_on x coe $ by { rintro _ _ ⟨_⟩, exact (coe_add_period p a).symm },
left_inv := (equiv_Ico p a).symm_apply_apply,
right_inv := quot.ind $ by
{ rintro ⟨x, hx⟩,
have := _,
rcases ne_or_eq x (a + p) with h | rfl,
{ revert x, exact this },
{ rw ← quot.sound endpoint_ident.mk, exact this _ _ (lt_add_of_pos_right a hp.out).ne },
intros x hx h,
congr, ext1,
apply congr_arg subtype.val ((equiv_Ico p a).right_inv ⟨x, hx.1, hx.2.lt_of_ne h⟩) } }
lemma equiv_Icc_quot_comp_mk_eq_to_Ico_mod : equiv_Icc_quot p a ∘ quotient.mk' =
λ x, quot.mk _ ⟨to_Ico_mod a hp.out x, Ico_subset_Icc_self $ to_Ico_mod_mem_Ico a _ x⟩ := rfl
lemma equiv_Icc_quot_comp_mk_eq_to_Ioc_mod : equiv_Icc_quot p a ∘ quotient.mk' =
λ x, quot.mk _ ⟨to_Ioc_mod a hp.out x, Ioc_subset_Icc_self $ to_Ioc_mod_mem_Ioc a _ x⟩ :=
begin
rw equiv_Icc_quot_comp_mk_eq_to_Ico_mod, funext,
by_cases mem_Ioo_mod a p x,
{ simp_rw (mem_Ioo_mod_iff_to_Ico_mod_eq_to_Ioc_mod hp.out).1 h },
{ simp_rw [not_imp_comm.1 (mem_Ioo_mod_iff_to_Ico_mod_ne_left hp.out).2 h,
not_imp_comm.1 (mem_Ioo_mod_iff_to_Ioc_mod_ne_right hp.out).2 h],
exact quot.sound endpoint_ident.mk },
end
/-- The natural map from `[a, a + p] ⊂ 𝕜` with endpoints identified to `𝕜 / ℤ • p`, as a
homeomorphism of topological spaces. -/
def homeo_Icc_quot : 𝕋 ≃ₜ quot (endpoint_ident p a) :=
{ to_equiv := equiv_Icc_quot p a,
continuous_to_fun := begin
simp_rw [quotient_map_quotient_mk.continuous_iff,
continuous_iff_continuous_at, continuous_at_iff_continuous_left_right],
intro x, split,
work_on_goal 1 { erw equiv_Icc_quot_comp_mk_eq_to_Ioc_mod },
work_on_goal 2 { erw equiv_Icc_quot_comp_mk_eq_to_Ico_mod },
all_goals { apply continuous_quot_mk.continuous_at.comp_continuous_within_at,
rw inducing_coe.continuous_within_at_iff },
{ apply continuous_left_to_Ioc_mod },
{ apply continuous_right_to_Ico_mod },
end,
continuous_inv_fun := continuous_quot_lift _
((add_circle.continuous_mk' p).comp continuous_subtype_coe) }
/-! We now show that a continuous function on `[a, a + p]` satisfying `f a = f (a + p)` is the
pullback of a continuous function on `add_circle p`. -/
variables {p a}
lemma lift_Ico_eq_lift_Icc {f : 𝕜 → B} (h : f a = f (a + p)) : lift_Ico p a f =
quot.lift (restrict (Icc a $ a + p) f) (by { rintro _ _ ⟨_⟩, exact h }) ∘ equiv_Icc_quot p a :=
rfl
lemma lift_Ico_continuous [topological_space B] {f : 𝕜 → B} (hf : f a = f (a + p))
(hc : continuous_on f $ Icc a (a + p)) : continuous (lift_Ico p a f) :=
begin
rw lift_Ico_eq_lift_Icc hf,
refine continuous.comp _ (homeo_Icc_quot p a).continuous_to_fun,
exact continuous_coinduced_dom.mpr (continuous_on_iff_continuous_restrict.mp hc),
end
section zero_based
lemma lift_Ico_zero_coe_apply {f : 𝕜 → B} {x : 𝕜} (hx : x ∈ Ico 0 p) :
lift_Ico p 0 f ↑x = f x := lift_Ico_coe_apply (by rwa zero_add)
lemma lift_Ico_zero_continuous [topological_space B] {f : 𝕜 → B}
(hf : f 0 = f p) (hc : continuous_on f $ Icc 0 p) : continuous (lift_Ico p 0 f) :=
lift_Ico_continuous (by rwa zero_add : f 0 = f (0 + p)) (by rwa zero_add)
end zero_based
end add_circle
end identify_Icc_ends
|
f115ffe0d7393c41e8eef5e1684163b0960ae5c1 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/order/filter/ultrafilter.lean | b7425161079337960fd4d0bdb7d7fda4f109ed9d | [] | no_license | AurelienSaue/Mathlib4_auto | f538cfd0980f65a6361eadea39e6fc639e9dae14 | 590df64109b08190abe22358fabc3eae000943f2 | refs/heads/master | 1,683,906,849,776 | 1,622,564,669,000 | 1,622,564,669,000 | 371,723,747 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 12,148 | lean | /-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Jeremy Avigad, Yury Kudryashov
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.order.filter.cofinite
import Mathlib.PostPort
universes u_1 l u v
namespace Mathlib
/-!
# Ultrafilters
An ultrafilter is a minimal (maximal in the set order) proper filter.
In this file we define
* `ultrafilter.of`: an ultrafilter that is less than or equal to a given filter;
* `ultrafilter`: subtype of ultrafilters;
* `ultrafilter.pure`: `pure x` as an `ultrafiler`;
* `ultrafilter.map`, `ultrafilter.bind`, `ultrafilter.comap` : operations on ultrafilters;
* `hyperfilter`: the ultrafilter extending the cofinite filter.
-/
/-- An ultrafilter is a minimal (maximal in the set order) proper filter. -/
structure ultrafilter (α : Type u_1)
extends filter α
where
ne_bot' : filter.ne_bot _to_filter
le_of_le : ∀ (g : filter α), filter.ne_bot g → g ≤ _to_filter → _to_filter ≤ g
namespace ultrafilter
protected instance filter.has_coe_t {α : Type u} : has_coe_t (ultrafilter α) (filter α) :=
has_coe_t.mk ultrafilter.to_filter
protected instance has_mem {α : Type u} : has_mem (set α) (ultrafilter α) :=
has_mem.mk fun (s : set α) (f : ultrafilter α) => s ∈ ↑f
theorem unique {α : Type u} (f : ultrafilter α) {g : filter α} (h : g ≤ ↑f) (hne : autoParam (filter.ne_bot g)
(Lean.Syntax.ident Lean.SourceInfo.none (String.toSubstring "Mathlib.tactic.apply_instance")
(Lean.Name.mkStr (Lean.Name.mkStr (Lean.Name.mkStr Lean.Name.anonymous "Mathlib") "tactic") "apply_instance") [])) : g = ↑f :=
le_antisymm h (ultrafilter.le_of_le f g hne h)
protected instance ne_bot {α : Type u} (f : ultrafilter α) : filter.ne_bot ↑f :=
ultrafilter.ne_bot' f
@[simp] theorem mem_coe {α : Type u} {f : ultrafilter α} {s : set α} : s ∈ ↑f ↔ s ∈ f :=
iff.rfl
theorem coe_injective {α : Type u} : function.injective coe := sorry
@[simp] theorem coe_le_coe {α : Type u} {f : ultrafilter α} {g : ultrafilter α} : ↑f ≤ ↑g ↔ f = g :=
{ mp := fun (h : ↑f ≤ ↑g) => coe_injective (unique g h), mpr := fun (h : f = g) => h ▸ le_rfl }
@[simp] theorem coe_inj {α : Type u} {f : ultrafilter α} {g : ultrafilter α} : ↑f = ↑g ↔ f = g :=
function.injective.eq_iff coe_injective
theorem ext {α : Type u} {f : ultrafilter α} {g : ultrafilter α} (h : ∀ (s : set α), s ∈ f ↔ s ∈ g) : f = g :=
coe_injective (filter.ext h)
theorem le_of_inf_ne_bot {α : Type u} (f : ultrafilter α) {g : filter α} (hg : filter.ne_bot (↑f ⊓ g)) : ↑f ≤ g :=
le_of_inf_eq (unique f inf_le_left)
theorem le_of_inf_ne_bot' {α : Type u} (f : ultrafilter α) {g : filter α} (hg : filter.ne_bot (g ⊓ ↑f)) : ↑f ≤ g :=
le_of_inf_ne_bot f (eq.mpr (id (Eq._oldrec (Eq.refl (filter.ne_bot (↑f ⊓ g))) inf_comm)) hg)
@[simp] theorem compl_not_mem_iff {α : Type u} {f : ultrafilter α} {s : set α} : ¬sᶜ ∈ f ↔ s ∈ f := sorry
@[simp] theorem frequently_iff_eventually {α : Type u} {f : ultrafilter α} {p : α → Prop} : filter.frequently (fun (x : α) => p x) ↑f ↔ filter.eventually (fun (x : α) => p x) ↑f :=
compl_not_mem_iff
theorem Mathlib.filter.frequently.eventually {α : Type u} {f : ultrafilter α} {p : α → Prop} : filter.frequently (fun (x : α) => p x) ↑f → filter.eventually (fun (x : α) => p x) ↑f :=
iff.mp frequently_iff_eventually
theorem compl_mem_iff_not_mem {α : Type u} {f : ultrafilter α} {s : set α} : sᶜ ∈ f ↔ ¬s ∈ f :=
eq.mpr (id (Eq._oldrec (Eq.refl (sᶜ ∈ f ↔ ¬s ∈ f)) (Eq.symm (propext compl_not_mem_iff))))
(eq.mpr (id (Eq._oldrec (Eq.refl (¬sᶜᶜ ∈ f ↔ ¬s ∈ f)) (compl_compl s))) (iff.refl (¬s ∈ f)))
/-- If `sᶜ ∉ f ↔ s ∈ f`, then `f` is an ultrafilter. The other implication is given by
`ultrafilter.compl_not_mem_iff`. -/
def of_compl_not_mem_iff {α : Type u} (f : filter α) (h : ∀ (s : set α), ¬sᶜ ∈ f ↔ s ∈ f) : ultrafilter α :=
mk f sorry sorry
theorem nonempty_of_mem {α : Type u} {f : ultrafilter α} {s : set α} (hs : s ∈ f) : set.nonempty s :=
filter.nonempty_of_mem_sets hs
theorem ne_empty_of_mem {α : Type u} {f : ultrafilter α} {s : set α} (hs : s ∈ f) : s ≠ ∅ :=
set.nonempty.ne_empty (nonempty_of_mem hs)
@[simp] theorem empty_not_mem {α : Type u} {f : ultrafilter α} : ¬∅ ∈ f :=
filter.empty_nmem_sets ↑f
theorem mem_or_compl_mem {α : Type u} (f : ultrafilter α) (s : set α) : s ∈ f ∨ sᶜ ∈ f :=
iff.mpr or_iff_not_imp_left (iff.mpr compl_mem_iff_not_mem)
protected theorem em {α : Type u} (f : ultrafilter α) (p : α → Prop) : filter.eventually (fun (x : α) => p x) ↑f ∨ filter.eventually (fun (x : α) => ¬p x) ↑f :=
mem_or_compl_mem f (set_of fun (x : α) => p x)
theorem eventually_or {α : Type u} {f : ultrafilter α} {p : α → Prop} {q : α → Prop} : filter.eventually (fun (x : α) => p x ∨ q x) ↑f ↔
filter.eventually (fun (x : α) => p x) ↑f ∨ filter.eventually (fun (x : α) => q x) ↑f := sorry
theorem union_mem_iff {α : Type u} {f : ultrafilter α} {s : set α} {t : set α} : s ∪ t ∈ f ↔ s ∈ f ∨ t ∈ f :=
eventually_or
theorem eventually_not {α : Type u} {f : ultrafilter α} {p : α → Prop} : filter.eventually (fun (x : α) => ¬p x) ↑f ↔ ¬filter.eventually (fun (x : α) => p x) ↑f :=
compl_mem_iff_not_mem
theorem eventually_imp {α : Type u} {f : ultrafilter α} {p : α → Prop} {q : α → Prop} : filter.eventually (fun (x : α) => p x → q x) ↑f ↔
filter.eventually (fun (x : α) => p x) ↑f → filter.eventually (fun (x : α) => q x) ↑f := sorry
theorem finite_sUnion_mem_iff {α : Type u} {f : ultrafilter α} {s : set (set α)} (hs : set.finite s) : ⋃₀s ∈ f ↔ ∃ (t : set α), ∃ (H : t ∈ s), t ∈ f := sorry
theorem finite_bUnion_mem_iff {α : Type u} {β : Type v} {f : ultrafilter α} {is : set β} {s : β → set α} (his : set.finite is) : (set.Union fun (i : β) => set.Union fun (H : i ∈ is) => s i) ∈ f ↔ ∃ (i : β), ∃ (H : i ∈ is), s i ∈ f := sorry
/-- Pushforward for ultrafilters. -/
def map {α : Type u} {β : Type v} (m : α → β) (f : ultrafilter α) : ultrafilter β :=
of_compl_not_mem_iff (filter.map m ↑f) sorry
@[simp] theorem coe_map {α : Type u} {β : Type v} (m : α → β) (f : ultrafilter α) : ↑(map m f) = filter.map m ↑f :=
rfl
@[simp] theorem mem_map {α : Type u} {β : Type v} {m : α → β} {f : ultrafilter α} {s : set β} : s ∈ map m f ↔ m ⁻¹' s ∈ f :=
iff.rfl
/-- The pullback of an ultrafilter along an injection whose range is large with respect to the given
ultrafilter. -/
def comap {α : Type u} {β : Type v} {m : α → β} (u : ultrafilter β) (inj : function.injective m) (large : set.range m ∈ u) : ultrafilter α :=
mk (filter.comap m ↑u) sorry sorry
/-- The principal ultrafilter associated to a point `x`. -/
protected instance has_pure : Pure ultrafilter :=
{ pure := fun (α : Type u_1) (a : α) => of_compl_not_mem_iff (pure a) sorry }
@[simp] theorem mem_pure_sets {α : Type u} {a : α} {s : set α} : s ∈ pure a ↔ a ∈ s :=
iff.rfl
protected instance inhabited {α : Type u} [Inhabited α] : Inhabited (ultrafilter α) :=
{ default := pure Inhabited.default }
/-- Monadic bind for ultrafilters, coming from the one on filters
defined in terms of map and join.-/
def bind {α : Type u} {β : Type v} (f : ultrafilter α) (m : α → ultrafilter β) : ultrafilter β :=
of_compl_not_mem_iff (filter.bind ↑f fun (x : α) => ↑(m x)) sorry
protected instance ultrafilter.has_bind : Bind ultrafilter :=
{ bind := bind }
protected instance ultrafilter.functor : Functor ultrafilter :=
{ map := map, mapConst := fun (α β : Type u_1) => map ∘ function.const β }
protected instance ultrafilter.monad : Monad ultrafilter := sorry
protected instance ultrafilter.is_lawful_monad : is_lawful_monad ultrafilter :=
is_lawful_monad.mk
(fun (α β : Type u_1) (a : α) (f : α → ultrafilter β) => coe_injective (filter.pure_bind a (coe ∘ f)))
fun (α β γ : Type u_1) (f : ultrafilter α) (m₁ : α → ultrafilter β) (m₂ : β → ultrafilter γ) =>
coe_injective (filter.filter_eq rfl)
/-- The ultrafilter lemma: Any proper filter is contained in an ultrafilter. -/
theorem exists_le {α : Type u} (f : filter α) [h : filter.ne_bot f] : ∃ (u : ultrafilter α), ↑u ≤ f := sorry
theorem Mathlib.filter.exists_ultrafilter_le {α : Type u} (f : filter α) [h : filter.ne_bot f] : ∃ (u : ultrafilter α), ↑u ≤ f :=
exists_le
/-- Construct an ultrafilter extending a given filter.
The ultrafilter lemma is the assertion that such a filter exists;
we use the axiom of choice to pick one. -/
def of {α : Type u} (f : filter α) [filter.ne_bot f] : ultrafilter α :=
classical.some (exists_le f)
theorem of_le {α : Type u} (f : filter α) [filter.ne_bot f] : ↑(of f) ≤ f :=
classical.some_spec (exists_le f)
theorem of_coe {α : Type u} (f : ultrafilter α) : of ↑f = f :=
iff.mp coe_inj (unique f (of_le ↑f))
theorem exists_ultrafilter_of_finite_inter_nonempty {α : Type u} (S : set (set α)) (cond : ∀ (T : finset (set α)), ↑T ⊆ S → set.nonempty (⋂₀↑T)) : ∃ (F : ultrafilter α), S ⊆ filter.sets (ultrafilter.to_filter F) := sorry
end ultrafilter
namespace filter
theorem mem_iff_ultrafilter {α : Type u} {s : set α} {f : filter α} : s ∈ f ↔ ∀ (g : ultrafilter α), ↑g ≤ f → s ∈ g := sorry
theorem le_iff_ultrafilter {α : Type u} {f₁ : filter α} {f₂ : filter α} : f₁ ≤ f₂ ↔ ∀ (g : ultrafilter α), ↑g ≤ f₁ → ↑g ≤ f₂ := sorry
/-- A filter equals the intersection of all the ultrafilters which contain it. -/
theorem supr_ultrafilter_le_eq {α : Type u} (f : filter α) : (supr fun (g : ultrafilter α) => supr fun (hg : ↑g ≤ f) => ↑g) = f := sorry
/-- The `tendsto` relation can be checked on ultrafilters. -/
theorem tendsto_iff_ultrafilter {α : Type u} {β : Type v} (f : α → β) (l₁ : filter α) (l₂ : filter β) : tendsto f l₁ l₂ ↔ ∀ (g : ultrafilter α), ↑g ≤ l₁ → tendsto f (↑g) l₂ := sorry
theorem exists_ultrafilter_iff {α : Type u} {f : filter α} : (∃ (u : ultrafilter α), ↑u ≤ f) ↔ ne_bot f := sorry
theorem forall_ne_bot_le_iff {α : Type u} {g : filter α} {p : filter α → Prop} (hp : monotone p) : (∀ (f : filter α), ne_bot f → f ≤ g → p f) ↔ ∀ (f : ultrafilter α), ↑f ≤ g → p ↑f := sorry
/-- The ultrafilter extending the cofinite filter. -/
def hyperfilter (α : Type u) [infinite α] : ultrafilter α :=
ultrafilter.of cofinite
theorem hyperfilter_le_cofinite {α : Type u} [infinite α] : ↑(hyperfilter α) ≤ cofinite :=
ultrafilter.of_le cofinite
@[simp] theorem bot_ne_hyperfilter {α : Type u} [infinite α] : ⊥ ≠ ↑(hyperfilter α) :=
ne.symm ((fun (this : ne_bot ↑(hyperfilter α)) => this) (ultrafilter.ne_bot (hyperfilter α)))
theorem nmem_hyperfilter_of_finite {α : Type u} [infinite α] {s : set α} (hf : set.finite s) : ¬s ∈ hyperfilter α :=
fun (hy : s ∈ hyperfilter α) => compl_not_mem_sets hy (hyperfilter_le_cofinite (set.finite.compl_mem_cofinite hf))
theorem Mathlib.set.finite.nmem_hyperfilter {α : Type u} [infinite α] {s : set α} (hf : set.finite s) : ¬s ∈ hyperfilter α :=
nmem_hyperfilter_of_finite
theorem compl_mem_hyperfilter_of_finite {α : Type u} [infinite α] {s : set α} (hf : set.finite s) : sᶜ ∈ hyperfilter α :=
iff.mpr ultrafilter.compl_mem_iff_not_mem (set.finite.nmem_hyperfilter hf)
theorem Mathlib.set.finite.compl_mem_hyperfilter {α : Type u} [infinite α] {s : set α} (hf : set.finite s) : sᶜ ∈ hyperfilter α :=
compl_mem_hyperfilter_of_finite
theorem mem_hyperfilter_of_finite_compl {α : Type u} [infinite α] {s : set α} (hf : set.finite (sᶜ)) : s ∈ hyperfilter α :=
compl_compl s ▸ set.finite.compl_mem_hyperfilter hf
|
867299956240cb72aa7714426d760929263f267a | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/data/list/pairwise.lean | b186482bb8485abf180a25a107482ba5181e9550 | [
"Apache-2.0"
] | permissive | leanprover-community/mathlib | 56a2cadd17ac88caf4ece0a775932fa26327ba0e | 442a83d738cb208d3600056c489be16900ba701d | refs/heads/master | 1,693,584,102,358 | 1,693,471,902,000 | 1,693,471,902,000 | 97,922,418 | 1,595 | 352 | Apache-2.0 | 1,694,693,445,000 | 1,500,624,130,000 | Lean | UTF-8 | Lean | false | false | 17,545 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
-/
import data.list.count
import data.list.lex
import logic.pairwise
import logic.relation
/-!
# Pairwise relations on a list
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
This file provides basic results about `list.pairwise` and `list.pw_filter` (definitions are in
`data.list.defs`).
`pairwise r [a 0, ..., a (n - 1)]` means `∀ i j, i < j → r (a i) (a j)`. For example,
`pairwise (≠) l` means that all elements of `l` are distinct, and `pairwise (<) l` means that `l`
is strictly increasing.
`pw_filter r l` is the list obtained by iteratively adding each element of `l` that doesn't break
the pairwiseness of the list we have so far. It thus yields `l'` a maximal sublist of `l` such that
`pairwise r l'`.
## Tags
sorted, nodup
-/
open nat function
namespace list
variables {α β : Type*} {R S T: α → α → Prop} {a : α} {l : list α}
mk_iff_of_inductive_prop list.pairwise list.pairwise_iff
/-! ### Pairwise -/
lemma rel_of_pairwise_cons (p : (a :: l).pairwise R) : ∀ {a'}, a' ∈ l → R a a' :=
(pairwise_cons.1 p).1
lemma pairwise.of_cons (p : (a :: l).pairwise R) : pairwise R l := (pairwise_cons.1 p).2
theorem pairwise.tail : ∀ {l : list α} (p : pairwise R l), pairwise R l.tail
| [] h := h
| (a :: l) h := h.of_cons
theorem pairwise.drop : ∀ {l : list α} {n : ℕ}, list.pairwise R l → list.pairwise R (l.drop n)
| _ 0 h := h
| [] (n + 1) h := list.pairwise.nil
| (a :: l) (n + 1) h := pairwise.drop (pairwise_cons.mp h).right
theorem pairwise.imp_of_mem {S : α → α → Prop} {l : list α}
(H : ∀ {a b}, a ∈ l → b ∈ l → R a b → S a b) (p : pairwise R l) : pairwise S l :=
begin
induction p with a l r p IH generalizing H; constructor,
{ exact ball.imp_right
(λ x h, H (mem_cons_self _ _) (mem_cons_of_mem _ h)) r },
{ exact IH (λ a b m m', H
(mem_cons_of_mem _ m) (mem_cons_of_mem _ m')) }
end
lemma pairwise.imp (H : ∀ a b, R a b → S a b) : pairwise R l → pairwise S l :=
pairwise.imp_of_mem (λ a b _ _, H a b)
lemma pairwise_and_iff : l.pairwise (λ a b, R a b ∧ S a b) ↔ l.pairwise R ∧ l.pairwise S :=
⟨λ h, ⟨h.imp (λ a b h, h.1), h.imp (λ a b h, h.2)⟩,
λ ⟨hR, hS⟩, begin
clear_, induction hR with a l R1 R2 IH;
simp only [pairwise.nil, pairwise_cons] at *,
exact ⟨λ b bl, ⟨R1 b bl, hS.1 b bl⟩, IH hS.2⟩
end⟩
lemma pairwise.and (hR : l.pairwise R) (hS : l.pairwise S) : l.pairwise (λ a b, R a b ∧ S a b) :=
pairwise_and_iff.2 ⟨hR, hS⟩
lemma pairwise.imp₂ (H : ∀ a b, R a b → S a b → T a b) (hR : l.pairwise R) (hS : l.pairwise S) :
l.pairwise T :=
(hR.and hS).imp $ λ a b, and.rec (H a b)
theorem pairwise.iff_of_mem {S : α → α → Prop} {l : list α}
(H : ∀ {a b}, a ∈ l → b ∈ l → (R a b ↔ S a b)) : pairwise R l ↔ pairwise S l :=
⟨pairwise.imp_of_mem (λ a b m m', (H m m').1),
pairwise.imp_of_mem (λ a b m m', (H m m').2)⟩
theorem pairwise.iff {S : α → α → Prop}
(H : ∀ a b, R a b ↔ S a b) {l : list α} : pairwise R l ↔ pairwise S l :=
pairwise.iff_of_mem (λ a b _ _, H a b)
theorem pairwise_of_forall {l : list α} (H : ∀ x y, R x y) : pairwise R l :=
by induction l; [exact pairwise.nil,
simp only [*, pairwise_cons, forall_2_true_iff, and_true]]
theorem pairwise.and_mem {l : list α} :
pairwise R l ↔ pairwise (λ x y, x ∈ l ∧ y ∈ l ∧ R x y) l :=
pairwise.iff_of_mem (by simp only [true_and, iff_self, forall_2_true_iff] {contextual := tt})
theorem pairwise.imp_mem {l : list α} :
pairwise R l ↔ pairwise (λ x y, x ∈ l → y ∈ l → R x y) l :=
pairwise.iff_of_mem
(by simp only [forall_prop_of_true, iff_self, forall_2_true_iff] {contextual := tt})
protected lemma pairwise.sublist : Π {l₁ l₂ : list α}, l₁ <+ l₂ → pairwise R l₂ → pairwise R l₁
| ._ ._ sublist.slnil h := h
| ._ ._ (sublist.cons l₁ l₂ a s) (pairwise.cons i h) := h.sublist s
| ._ ._ (sublist.cons2 l₁ l₂ a s) (pairwise.cons i h) :=
(h.sublist s).cons (ball.imp_left s.subset i)
lemma pairwise.forall_of_forall_of_flip (h₁ : ∀ x ∈ l, R x x) (h₂ : l.pairwise R)
(h₃ : l.pairwise (flip R)) :
∀ ⦃x⦄, x ∈ l → ∀ ⦃y⦄, y ∈ l → R x y :=
begin
induction l with a l ih,
{ exact forall_mem_nil _ },
rw pairwise_cons at h₂ h₃,
rintro x (rfl | hx) y (rfl | hy),
{ exact h₁ _ (l.mem_cons_self _) },
{ exact h₂.1 _ hy },
{ exact h₃.1 _ hx },
{ exact ih (λ x hx, h₁ _ $ mem_cons_of_mem _ hx) h₂.2 h₃.2 hx hy }
end
lemma pairwise.forall_of_forall (H : symmetric R) (H₁ : ∀ x ∈ l, R x x) (H₂ : l.pairwise R) :
∀ ⦃x⦄, x ∈ l → ∀ ⦃y⦄, y ∈ l → R x y :=
H₂.forall_of_forall_of_flip H₁ $ by rwa H.flip_eq
lemma pairwise.forall (hR : symmetric R) (hl : l.pairwise R) :
∀ ⦃a⦄, a ∈ l → ∀ ⦃b⦄, b ∈ l → a ≠ b → R a b :=
pairwise.forall_of_forall
(λ a b h hne, hR (h hne.symm))
(λ _ _ h, (h rfl).elim)
(hl.imp $ λ _ _ h _, h)
lemma pairwise.set_pairwise (hl : pairwise R l) (hr : symmetric R) : {x | x ∈ l}.pairwise R :=
hl.forall hr
theorem pairwise_singleton (R) (a : α) : pairwise R [a] :=
by simp only [pairwise_cons, mem_singleton, forall_prop_of_false (not_mem_nil _), forall_true_iff,
pairwise.nil, and_true]
theorem pairwise_pair {a b : α} : pairwise R [a, b] ↔ R a b :=
by simp only [pairwise_cons, mem_singleton, forall_eq, forall_prop_of_false (not_mem_nil _),
forall_true_iff, pairwise.nil, and_true]
theorem pairwise_append {l₁ l₂ : list α} : pairwise R (l₁++l₂) ↔
pairwise R l₁ ∧ pairwise R l₂ ∧ ∀ x ∈ l₁, ∀ y ∈ l₂, R x y :=
by induction l₁ with x l₁ IH; [simp only [list.pairwise.nil, forall_prop_of_false (not_mem_nil _),
forall_true_iff, and_true, true_and, nil_append],
simp only [cons_append, pairwise_cons, forall_mem_append, IH, forall_mem_cons, forall_and_distrib,
and_assoc, and.left_comm]]
theorem pairwise_append_comm (s : symmetric R) {l₁ l₂ : list α} :
pairwise R (l₁++l₂) ↔ pairwise R (l₂++l₁) :=
have ∀ l₁ l₂ : list α,
(∀ (x : α), x ∈ l₁ → ∀ (y : α), y ∈ l₂ → R x y) →
(∀ (x : α), x ∈ l₂ → ∀ (y : α), y ∈ l₁ → R x y),
from λ l₁ l₂ a x xm y ym, s (a y ym x xm),
by simp only [pairwise_append, and.left_comm]; rw iff.intro (this l₁ l₂) (this l₂ l₁)
theorem pairwise_middle (s : symmetric R) {a : α} {l₁ l₂ : list α} :
pairwise R (l₁ ++ a :: l₂) ↔ pairwise R (a :: (l₁++l₂)) :=
show pairwise R (l₁ ++ ([a] ++ l₂)) ↔ pairwise R ([a] ++ l₁ ++ l₂),
by rw [← append_assoc, pairwise_append, @pairwise_append _ _ ([a] ++ l₁), pairwise_append_comm s];
simp only [mem_append, or_comm]
theorem pairwise_map (f : β → α) :
∀ {l : list β}, pairwise R (map f l) ↔ pairwise (λ a b : β, R (f a) (f b)) l
| [] := by simp only [map, pairwise.nil]
| (b :: l) :=
have (∀ a b', b' ∈ l → f b' = a → R (f b) a) ↔ ∀ (b' : β), b' ∈ l → R (f b) (f b'), from
forall_swap.trans $ forall_congr $ λ a, forall_swap.trans $ by simp only [forall_eq'],
by simp only [map, pairwise_cons, mem_map, exists_imp_distrib, and_imp, this, pairwise_map]
lemma pairwise.of_map {S : β → β → Prop} (f : α → β) (H : ∀ a b : α, S (f a) (f b) → R a b)
(p : pairwise S (map f l)) : pairwise R l :=
((pairwise_map f).1 p).imp H
lemma pairwise.map {S : β → β → Prop} (f : α → β) (H : ∀ a b : α, R a b → S (f a) (f b))
(p : pairwise R l) : pairwise S (map f l) :=
(pairwise_map f).2 $ p.imp H
theorem pairwise_filter_map (f : β → option α) {l : list β} :
pairwise R (filter_map f l) ↔ pairwise (λ a a' : β, ∀ (b ∈ f a) (b' ∈ f a'), R b b') l :=
let S (a a' : β) := ∀ (b ∈ f a) (b' ∈ f a'), R b b' in
begin
simp only [option.mem_def], induction l with a l IH,
{ simp only [filter_map, pairwise.nil] },
cases e : f a with b,
{ rw [filter_map_cons_none _ _ e, IH, pairwise_cons],
simp only [e, forall_prop_of_false not_false, forall_3_true_iff, true_and] },
rw [filter_map_cons_some _ _ _ e],
simp only [pairwise_cons, mem_filter_map, exists_imp_distrib, and_imp, IH, e, forall_eq'],
show (∀ (a' : α) (x : β), x ∈ l → f x = some a' → R b a') ∧ pairwise S l ↔
(∀ (a' : β), a' ∈ l → ∀ (b' : α), f a' = some b' → R b b') ∧ pairwise S l,
from and_congr ⟨λ h b mb a ma, h a b mb ma, λ h a b mb ma, h b mb a ma⟩ iff.rfl
end
theorem pairwise.filter_map {S : β → β → Prop} (f : α → option β)
(H : ∀ (a a' : α), R a a' → ∀ (b ∈ f a) (b' ∈ f a'), S b b') {l : list α}
(p : pairwise R l) : pairwise S (filter_map f l) :=
(pairwise_filter_map _).2 $ p.imp H
theorem pairwise_filter (p : α → Prop) [decidable_pred p] {l : list α} :
pairwise R (filter p l) ↔ pairwise (λ x y, p x → p y → R x y) l :=
begin
rw [← filter_map_eq_filter, pairwise_filter_map],
apply pairwise.iff, intros, simp only [option.mem_def, option.guard_eq_some, and_imp, forall_eq'],
end
lemma pairwise.filter (p : α → Prop) [decidable_pred p] : pairwise R l → pairwise R (filter p l) :=
pairwise.sublist (filter_sublist _)
theorem pairwise_pmap {p : β → Prop} {f : Π b, p b → α} {l : list β} (h : ∀ x ∈ l, p x) :
pairwise R (l.pmap f h) ↔
pairwise (λ b₁ b₂, ∀ (h₁ : p b₁) (h₂ : p b₂), R (f b₁ h₁) (f b₂ h₂)) l :=
begin
induction l with a l ihl, { simp },
obtain ⟨ha, hl⟩ : p a ∧ ∀ b, b ∈ l → p b, by simpa using h,
simp only [ihl hl, pairwise_cons, bex_imp_distrib, pmap, and.congr_left_iff, mem_pmap],
refine λ _, ⟨λ H b hb hpa hpb, H _ _ hb rfl, _⟩,
rintro H _ b hb rfl,
exact H b hb _ _
end
theorem pairwise.pmap {l : list α} (hl : pairwise R l)
{p : α → Prop} {f : Π a, p a → β} (h : ∀ x ∈ l, p x) {S : β → β → Prop}
(hS : ∀ ⦃x⦄ (hx : p x) ⦃y⦄ (hy : p y), R x y → S (f x hx) (f y hy)) :
pairwise S (l.pmap f h) :=
begin
refine (pairwise_pmap h).2 (pairwise.imp_of_mem _ hl),
intros, apply hS, assumption
end
theorem pairwise_join {L : list (list α)} : pairwise R (join L) ↔
(∀ l ∈ L, pairwise R l) ∧ pairwise (λ l₁ l₂, ∀ (x ∈ l₁) (y ∈ l₂), R x y) L :=
begin
induction L with l L IH,
{simp only [join, pairwise.nil, forall_prop_of_false (not_mem_nil _), forall_const, and_self]},
have : (∀ (x : α), x ∈ l → ∀ (y : α) (x_1 : list α), x_1 ∈ L → y ∈ x_1 → R x y) ↔
∀ (a' : list α), a' ∈ L → ∀ (x : α), x ∈ l → ∀ (y : α), y ∈ a' → R x y :=
⟨λ h a b c d e, h c d e a b, λ h c d e a b, h a b c d e⟩,
simp only [join, pairwise_append, IH, mem_join, exists_imp_distrib, and_imp, this,
forall_mem_cons, pairwise_cons],
simp only [and_assoc, and_comm, and.left_comm],
end
lemma pairwise_bind {R : β → β → Prop} {l : list α} {f : α → list β} :
list.pairwise R (l.bind f) ↔
(∀ a ∈ l, pairwise R (f a)) ∧ pairwise (λ a₁ a₂, ∀ (x ∈ f a₁) (y ∈ f a₂), R x y) l :=
by simp [list.bind, list.pairwise_join, list.mem_map, list.pairwise_map]
@[simp] theorem pairwise_reverse : ∀ {R} {l : list α},
pairwise R (reverse l) ↔ pairwise (λ x y, R y x) l :=
suffices ∀ {R l}, @pairwise α R l → pairwise (λ x y, R y x) (reverse l),
from λ R l, ⟨λ p, reverse_reverse l ▸ this p, this⟩,
λ R l p, by induction p with a l h p IH;
[apply pairwise.nil, simpa only [reverse_cons, pairwise_append, IH,
pairwise_cons, forall_prop_of_false (not_mem_nil _), forall_true_iff,
pairwise.nil, mem_reverse, mem_singleton, forall_eq, true_and] using h]
lemma pairwise_of_reflexive_on_dupl_of_forall_ne [decidable_eq α] {l : list α} {r : α → α → Prop}
(hr : ∀ a, 1 < count a l → r a a)
(h : ∀ (a ∈ l) (b ∈ l), a ≠ b → r a b) : l.pairwise r :=
begin
induction l with hd tl IH,
{ simp },
{ rw list.pairwise_cons,
split,
{ intros x hx,
by_cases H : hd = x,
{ rw H,
refine hr _ _,
simpa [count_cons, H, nat.succ_lt_succ_iff, count_pos] using hx },
{ exact h hd (mem_cons_self _ _) x (mem_cons_of_mem _ hx) H } },
{ refine IH _ _,
{ intros x hx,
refine hr _ _,
rw count_cons,
split_ifs,
{ exact hx.trans (nat.lt_succ_self _) },
{ exact hx } },
{ intros x hx y hy,
exact h x (mem_cons_of_mem _ hx) y (mem_cons_of_mem _ hy) } } }
end
lemma pairwise_of_forall_mem_list {l : list α} {r : α → α → Prop} (h : ∀ (a ∈ l) (b ∈ l), r a b) :
l.pairwise r :=
begin
classical,
refine pairwise_of_reflexive_on_dupl_of_forall_ne (λ a ha', _) (λ a ha b hb _, h a ha b hb),
have ha := list.one_le_count_iff_mem.1 ha'.le,
exact h a ha a ha
end
lemma pairwise_of_reflexive_of_forall_ne {l : list α} {r : α → α → Prop}
(hr : reflexive r) (h : ∀ (a ∈ l) (b ∈ l), a ≠ b → r a b) : l.pairwise r :=
by { classical, exact pairwise_of_reflexive_on_dupl_of_forall_ne (λ _ _, hr _) h }
theorem pairwise_iff_nth_le {R} : ∀ {l : list α},
pairwise R l ↔ ∀ i j (h₁ : j < length l) (h₂ : i < j),
R (nth_le l i (lt_trans h₂ h₁)) (nth_le l j h₁)
| [] := by simp only [pairwise.nil, true_iff]; exact λ i j h, (nat.not_lt_zero j).elim h
| (a :: l) := begin
rw [pairwise_cons, pairwise_iff_nth_le],
refine ⟨λ H i j h₁ h₂, _, λ H, ⟨λ a' m, _,
λ i j h₁ h₂, H _ _ (succ_lt_succ h₁) (succ_lt_succ h₂)⟩⟩,
{ cases j with j, {exact (nat.not_lt_zero _).elim h₂},
cases i with i,
{ exact H.1 _ (nth_le_mem l _ _) },
{ exact H.2 _ _ (lt_of_succ_lt_succ h₁) (lt_of_succ_lt_succ h₂) } },
{ rcases nth_le_of_mem m with ⟨n, h, rfl⟩,
exact H _ _ (succ_lt_succ h) (succ_pos _) }
end
lemma pairwise_replicate {α : Type*} {r : α → α → Prop} {x : α} (hx : r x x) :
∀ (n : ℕ), pairwise r (replicate n x)
| 0 := by simp
| (n+1) := by simp [hx, mem_replicate, pairwise_replicate n]
/-! ### Pairwise filtering -/
variable [decidable_rel R]
@[simp] theorem pw_filter_nil : pw_filter R [] = [] := rfl
@[simp] theorem pw_filter_cons_of_pos {a : α} {l : list α} (h : ∀ b ∈ pw_filter R l, R a b) :
pw_filter R (a :: l) = a :: pw_filter R l := if_pos h
@[simp] theorem pw_filter_cons_of_neg {a : α} {l : list α} (h : ¬ ∀ b ∈ pw_filter R l, R a b) :
pw_filter R (a :: l) = pw_filter R l := if_neg h
theorem pw_filter_map (f : β → α) :
Π (l : list β), pw_filter R (map f l) = map f (pw_filter (λ x y, R (f x) (f y)) l)
| [] := rfl
| (x :: xs) :=
if h : ∀ b ∈ pw_filter R (map f xs), R (f x) b
then have h' : ∀ (b : β), b ∈ pw_filter (λ (x y : β), R (f x) (f y)) xs → R (f x) (f b),
from λ b hb, h _ (by rw [pw_filter_map]; apply mem_map_of_mem _ hb),
by rw [map,pw_filter_cons_of_pos h,pw_filter_cons_of_pos h',pw_filter_map,map]
else have h' : ¬∀ (b : β), b ∈ pw_filter (λ (x y : β), R (f x) (f y)) xs → R (f x) (f b),
from λ hh, h $ λ a ha,
by { rw [pw_filter_map,mem_map] at ha, rcases ha with ⟨b,hb₀,hb₁⟩,
subst a, exact hh _ hb₀, },
by rw [map,pw_filter_cons_of_neg h,pw_filter_cons_of_neg h',pw_filter_map]
theorem pw_filter_sublist : ∀ (l : list α), pw_filter R l <+ l
| [] := nil_sublist _
| (x :: l) := begin
by_cases (∀ y ∈ pw_filter R l, R x y),
{ rw [pw_filter_cons_of_pos h],
exact (pw_filter_sublist l).cons_cons _ },
{ rw [pw_filter_cons_of_neg h],
exact sublist_cons_of_sublist _ (pw_filter_sublist l) },
end
theorem pw_filter_subset (l : list α) : pw_filter R l ⊆ l :=
(pw_filter_sublist _).subset
theorem pairwise_pw_filter : ∀ (l : list α), pairwise R (pw_filter R l)
| [] := pairwise.nil
| (x :: l) := begin
by_cases (∀ y ∈ pw_filter R l, R x y),
{ rw [pw_filter_cons_of_pos h],
exact pairwise_cons.2 ⟨h, pairwise_pw_filter l⟩ },
{ rw [pw_filter_cons_of_neg h],
exact pairwise_pw_filter l },
end
theorem pw_filter_eq_self {l : list α} : pw_filter R l = l ↔ pairwise R l :=
⟨λ e, e ▸ pairwise_pw_filter l, λ p, begin
induction l with x l IH, {refl},
cases pairwise_cons.1 p with al p,
rw [pw_filter_cons_of_pos (ball.imp_left (pw_filter_subset l) al), IH p],
end⟩
alias pw_filter_eq_self ↔ _ pairwise.pw_filter
attribute [protected] pairwise.pw_filter
@[simp] lemma pw_filter_idempotent : pw_filter R (pw_filter R l) = pw_filter R l :=
(pairwise_pw_filter l).pw_filter
theorem forall_mem_pw_filter (neg_trans : ∀ {x y z}, R x z → R x y ∨ R y z)
(a : α) (l : list α) : (∀ b ∈ pw_filter R l, R a b) ↔ (∀ b ∈ l, R a b) :=
⟨begin
induction l with x l IH, { exact λ _ _, false.elim },
simp only [forall_mem_cons],
by_cases (∀ y ∈ pw_filter R l, R x y); dsimp at h,
{ simp only [pw_filter_cons_of_pos h, forall_mem_cons, and_imp],
exact λ r H, ⟨r, IH H⟩ },
{ rw [pw_filter_cons_of_neg h],
refine λ H, ⟨_, IH H⟩,
cases e : find (λ y, ¬ R x y) (pw_filter R l) with k,
{ refine h.elim (ball.imp_right _ (find_eq_none.1 e)),
exact λ y _, not_not.1 },
{ have := find_some e,
exact (neg_trans (H k (find_mem e))).resolve_right this } }
end, ball.imp_left (pw_filter_subset l)⟩
end list
|
3a9ad0b006cde8218de02ee5f12f1c254cc9af74 | 80cc5bf14c8ea85ff340d1d747a127dcadeb966f | /src/group_theory/abelianization.lean | cbe69c125705b534a051a48695c95c3877a2c919 | [
"Apache-2.0"
] | permissive | lacker/mathlib | f2439c743c4f8eb413ec589430c82d0f73b2d539 | ddf7563ac69d42cfa4a1bfe41db1fed521bd795f | refs/heads/master | 1,671,948,326,773 | 1,601,479,268,000 | 1,601,479,268,000 | 298,686,743 | 0 | 0 | Apache-2.0 | 1,601,070,794,000 | 1,601,070,794,000 | null | UTF-8 | Lean | false | false | 2,455 | lean | /-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau, Michael Howes
The functor Grp → Ab which is the left adjoint
of the forgetful functor Ab → Grp.
-/
import group_theory.quotient_group
import tactic.group
universes u v
-- let G be a group
variables (G : Type u) [group G]
/-- The commutator subgroup of a group G is the normal subgroup
generated by the commutators [p,q]=`p*q*p⁻¹*q⁻¹` -/
@[derive subgroup.normal]
def commutator : subgroup G :=
subgroup.normal_closure {x | ∃ p q, p * q * p⁻¹ * q⁻¹ = x}
/-- The abelianization of G is the quotient of G by its commutator subgroup -/
def abelianization : Type u :=
quotient_group.quotient (commutator G)
namespace abelianization
local attribute [instance] quotient_group.left_rel
instance : comm_group (abelianization G) :=
{ mul_comm := λ x y, quotient.induction_on₂' x y $ λ a b,
begin
apply quotient.sound,
apply subgroup.subset_normal_closure,
use b⁻¹, use a⁻¹,
group,
end,
.. quotient_group.group _ }
instance : inhabited (abelianization G) := ⟨1⟩
variable {G}
/-- `of` is the canonical projection from G to its abelianization. -/
def of : G →* abelianization G :=
{ to_fun := quotient_group.mk,
map_one' := rfl,
map_mul' := λ x y, rfl }
section lift
-- so far -- built Gᵃᵇ and proved it's an abelian group.
-- defined `of : G → Gᵃᵇ`
-- let A be an abelian group and let f be a group hom from G to A
variables {A : Type v} [comm_group A] (f : G →* A)
lemma commutator_subset_ker : commutator G ≤ f.ker :=
begin
apply subgroup.normal_closure_le_normal,
rintros x ⟨p, q, rfl⟩,
simp [monoid_hom.mem_ker, mul_right_comm (f p) (f q)],
end
def lift : abelianization G →* A :=
quotient_group.lift _ f (λ x h, f.mem_ker.2 $ commutator_subset_ker _ h)
@[simp] lemma lift.of (x : G) : lift f (of x) = f x :=
rfl
theorem lift.unique
(φ : abelianization G →* A)
-- hφ : φ agrees with f on the image of G in Gᵃᵇ
(hφ : ∀ (x : G), φ (of x) = f x)
{x : abelianization G} :
φ x = lift f x :=
quotient_group.induction_on x hφ
end lift
variables {A : Type v} [monoid A]
theorem hom_ext (φ ψ : abelianization G →* A)
(h : φ.comp of = ψ.comp of) : φ = ψ :=
begin
ext x,
apply quotient_group.induction_on x,
intro z,
show φ.comp of z = _,
rw h,
refl,
end
end abelianization
|
b58ef26c412037ea07f415ae39d1f4b88510b6b4 | f10d66a159ce037d07005bd6021cee6bbd6d5ff0 | /poly_derivative.lean | 764e939d2e7250f75497a96d8668727c35c605a4 | [] | no_license | johoelzl/mason-stother | 0c78bca183eb729d7f0f93e87ce073bc8cd8808d | 573ecfaada288176462c03c87b80ad05bdab4644 | refs/heads/master | 1,631,751,973,492 | 1,528,923,934,000 | 1,528,923,934,000 | 109,133,224 | 0 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 11,466 | lean | import .Sup_fin data.finsupp order.lattice data.nat.cast .euclidean_domain unique_factorization_domain
import .to_finsupp .to_finset poly
universes u v w
noncomputable theory
open classical set function finsupp lattice
local attribute [instance] finsupp.to_comm_semiring
local attribute [instance] finsupp.to_semiring
local infix ^ := monoid.pow
namespace polynomial
local attribute [instance] prop_decidable
variables {α : Type u} {a a' a₁ a₂ : α} --{n m : ℕ} --do we want n and m?
--Formal derivatives
section semiring
variable [semiring α]
def derivative (p : polynomial α) : polynomial α :=
p.sum (λn a, nat.cases_on n 0 (λn, single n (a * (n + 1))))
-- TODO: the following form breaks derivative_single
-- p.sum (λn a, match n with 0 := 0 | n + 1 := single n (a * (n + 1)) end)
@[simp] lemma derivative_zero : derivative (0 : polynomial α) = 0 :=
finsupp.sum_zero_index
lemma derivative_single {n : ℕ} {a : α} :
derivative (single n a) = nat.cases_on n 0 (λn, single n (a * (n + 1))) :=
finsupp.sum_single_index $ match n with 0 := rfl | n + 1 := by simp [derivative]; refl end
@[simp] lemma derivative_single_zero {a : α} : derivative (single 0 a) = 0 :=
derivative_single
@[simp] lemma derivative_single_one {n : ℕ} {a : α} :
derivative (single (n + 1) a) = single n (a * (n + 1)) :=
derivative_single
@[simp] lemma derivative_C {a : α} : derivative (C a) = 0 :=
by simp [C]; refl
@[simp] lemma derivative_one : derivative (1 : polynomial α) = 0 :=
derivative_C
@[simp] lemma derivative_X : derivative (X : polynomial α) = 1 :=
by simp [X]; refl
@[simp] lemma derivative_add {f g : polynomial α} :
derivative (f + g) = derivative f + derivative g :=
finsupp.sum_add_index
(assume n, match n with 0 := rfl | n + 1 := by simp [derivative]; refl end)
(assume n, match n with
0 := assume b₁ b₂, (add_zero _).symm
| n + 1 := assume b₁ b₂, begin rw [← nat.succ_eq_add_one], simp [add_mul] end end)
@[simp] lemma derivative_sum {β : Type w} {s : finset β} {f : β → polynomial α} :
derivative (s.sum f) = s.sum (λb, derivative (f b)) :=
begin
apply (finset.sum_hom derivative _ _).symm,
exact derivative_zero,
exact assume x y, derivative_add
end
lemma derivative_eq_zero_of_is_constant {p : polynomial α} : (is_constant p) → (derivative p = 0) :=
begin
intro h1,
rw [is_constant] at h1,
rcases h1 with ⟨c, h2⟩,
simp [h2],
end
--We need characteristic_zero for derivative_eq_zero -> is_constant
end semiring
section comm_semiring
variable [comm_semiring α]
@[simp] lemma derivative_mul_C {f : polynomial α} : derivative (f * C a) = derivative f * C a :=
have ∀i c, derivative (single i (a * c)) = derivative (single i c) * C a,
by intros i c; cases i; simp [C, single_mul_single, mul_comm, mul_left_comm, mul_assoc],
calc derivative (f * C a) = derivative (f.sum (λi c, single i (a * c))) :
by rw [mul_C_eq_sum]
... = f.sum (λi c, derivative (single i (a * c))) : derivative_sum
... = f.sum (λi c, derivative (single i c) * C a) : by simp [this]
... = f.sum (λi c, derivative (single i c)) * C a : finset.sum_mul.symm
... = derivative (f.sum single) * C a : by simp [finsupp.sum, derivative_sum]
... = _ : by rw [sum_single]
@[simp] lemma derivative_C_mul {f : polynomial α} : derivative (C a * f) = C a * (derivative f) :=
by rw [mul_comm, derivative_mul_C, mul_comm]
private lemma derivative_mul_X_aux {f : polynomial α} : sum (derivative f) (λ (i : ℕ) (c : α), single (i + 1) c) = sum f (λ (i : ℕ) (c : α), single i (c * ↑i)) :=
begin
simp [derivative, sum_sum_index],
{
apply finsupp.sum_congr rfl,
{
intros n hnf,
cases n,
{ simp, apply sum_zero_index },
{ simp [sum_single_index]}
}
},
end
lemma derivative_mul_X {f : polynomial α} : derivative (f * X) = derivative f * X + f :=
calc derivative (f * X) = derivative (f.sum (λi c, single (i + 1) c)) :
by rw [mul_X_eq_sum]
... = f.sum (λi c, derivative (single (i + 1) c)) :
derivative_sum
... = f.sum (λi c, single i (c * (i + 1))) :
by simp [derivative_single, (nat.succ_eq_add_one _).symm]
... = f.sum (λi c, single i (c * i) + single i c) : by simp [single_add, mul_add]
... = f.sum (λi c, single i (c * i)) + f: by simp [sum_add, sum_single]
... = derivative f * X + f : by rw [mul_X_eq_sum, derivative_mul_X_aux]
lemma derivative_mul {f : polynomial α} :
∀{g}, derivative (f * g) = derivative f * g + f * derivative g :=
begin
apply f.induction_on_X,
{ simp [derivative_mul_C, mul_assoc, mul_comm, mul_left_comm] },
{ simp [add_mul, mul_add] {contextual := tt} },
{ intros p hp q,
rw [mul_assoc, hp, hp, mul_comm X q, derivative_mul_X],
simp [mul_add, add_mul, add_assoc, add_comm, add_left_comm, mul_assoc, mul_comm, mul_left_comm] }
end
open finset
lemma derivative_prod {β : Type w} {s : finset β} {f : β → polynomial α} :
derivative (s.prod f) = s.sum (λb, derivative (f b) * (erase s b).prod f) :=
begin
apply finset.induction_on s,
{ simp },
{
intros a s has ih,
have : ∀b∈s, ((insert a s).erase b).prod f = f a * (s.erase b).prod f,
{
assume b hb,
have : a ≠ b,
{
assume h, simp * at *
},
rw [erase_insert_eq_insert_erase, finset.prod_insert]; simp *
},
have : s.sum (λb, derivative (f b) * (erase (insert a s) b).prod f) =
f a * s.sum (λb, derivative (f b) * (erase s b).prod f),
{
exact calc s.sum (λb, derivative (f b) * (erase (insert a s) b).prod f) =
s.sum (λb, f a * (derivative (f b) * (s.erase b).prod f)) :
sum_congr rfl $ by simp [this, mul_assoc, mul_comm, mul_left_comm] {contextual := tt}
... = f a * s.sum (λb, derivative (f b) * (erase s b).prod f) : by rw [mul_sum],
},
simp [ih, has, finset.prod_insert, derivative_mul, sum_insert, erase_insert, this]
}
end
--Clean up done till here 9 april 2018
--For the lemmas below I did not try to refactor them yet.
lemma derivative_prod_multiset {s : multiset (polynomial α)} :
derivative (s.prod) = (s.map (λb, derivative (b) * (s.erase b).prod)).sum :=
begin
apply multiset.induction_on s,
{
simp * at *,
},
{
intros a s has,
simp * at *,
rw derivative_mul,
have h : multiset.sum (multiset.map (λ (b : polynomial α), derivative b * multiset.prod (multiset.erase (a :: s) b)) s) =
a * multiset.sum (multiset.map (λ (b : polynomial α), derivative b * multiset.prod (multiset.erase s b)) s),
{
exact calc multiset.sum (multiset.map (λ (b : polynomial α), derivative b * multiset.prod (multiset.erase (a :: s) b)) s) =
multiset.sum (multiset.map (λ (b : polynomial α), a * (derivative b * multiset.prod (multiset.erase (s) b))) s) :
begin
apply congr_arg,
apply multiset.map_congr,
intros x h,
by_cases h2 : x = a,
{
subst h2,
rw multiset.erase_cons_head,
rcases multiset.exists_cons_of_mem h with ⟨t, h⟩,
subst h,
simp [mul_comm x (derivative x)],
rw [←mul_assoc, ←mul_assoc, mul_comm x _],
},
{
simp [multiset.erase_cons_tail s (ne.symm h2), mul_comm a _,mul_assoc],
}
end
... = _ : @multiset.sum_map_mul (polynomial α) _ _ a _ s,
},
rw [h, has],
}
end
lemma derivative_pow {n : ℕ} {p : polynomial α}:
derivative (p^n) = ite (n = 0) 0 (n*p^(n-1)*derivative p) :=
begin
induction n with n h,
{ simp},
{
simp [if_neg, pow_succ', derivative_mul, nat.succ_ne_zero, *],
cases n,
{
simp,
},
{
simp [nat.succ_ne_zero, if_neg, pow_succ', *],
exact calc p ^ n * p * derivative p + (1 + ↑n) * p ^ n * derivative p * p =
1 * p ^ n * p * derivative p + (1 + ↑n) * p ^ n * derivative p * p : by simp
... = 1 * p ^ n * p * derivative p + (1 + ↑n) * p ^ n * (derivative p * p) : by simp [mul_assoc]
... = 1 * p ^ n * p * derivative p + (1 + ↑n) * p ^ n * (p * derivative p) : by simp [mul_comm]
... = 1 * p ^ n * p * derivative p + (1 + ↑n) * p ^ n * p * derivative p : by simp [mul_assoc]
... = 1 * (p ^ n * p * derivative p) + (1 + ↑n) * (p ^ n * p * derivative p) : by simp [mul_assoc]
... = (1 + (1 + ↑n)) * (p ^ n * p * derivative p): by rw [←( add_mul 1 (1 + ↑n) (p ^ n * p * derivative p))]
... = (1 + (1 + ↑n)) * (p ^ n * p) * derivative p : by simp [mul_assoc]
}
}
end
end comm_semiring
section integral_domain
variable [integral_domain α]
lemma derivative_apply {p : polynomial α} {n : ℕ} : derivative p n = (n + 1) * p (n + 1) :=
calc derivative p n = ({n + 1} : finset ℕ).sum (λm, (nat.cases_on m 0 (λn, single n (p m * (↑n + 1))) : polynomial α) n) :
begin
rw [derivative, sum_apply],
apply finset.sum_bij_ne_zero (λx _ _, x),
{ intro m, cases m,
{ dsimp, simp },
{ by_cases m = n,
{ dsimp, simp [single_apply, h] },
{ dsimp, simp [single_apply, h] } } },
{ intros m hm, exact id },
{ intros a₁ a₂ _ _ _ _, exact id },
{ dsimp, simp,
intro h,
refine ⟨n + 1, _, _, _⟩,
{ change (single n (p (n + 1) * (n + 1)) n ≠ 0) at h,
simp [mul_eq_zero, not_or_distrib] at h,
exact h.left },
{ assumption },
{ refl } },
{ dsimp, simp }
end
... = _ :
begin
simp,
change single n (p (n + 1) * (n + 1)) n = (1 + n) * p (n + 1),
simp [mul_comm]
end
--Why placed here?
lemma degree_derivative_le {p : polynomial α} : degree (derivative p) ≤ degree p - 1 :=
degree_le $ assume m hm,
have degree p < m + 1,
from calc degree p ≤ (degree p - 1) + 1 : nat.le_sub_add (degree p) 1
... ≤ m : hm
... < m + 1 : nat.lt_succ_self _,
have p (m + 1) = 0,
from eq_zero_of_gt_degree this,
by rw [derivative_apply, this, mul_zero]
--Problem with decidability propagated
lemma derivative_degree_sub_one_eq_degree_mul_leading_coeff {p : polynomial α} :
derivative p (degree p - 1) = degree p * (leading_coeff p) :=
begin
rw [leading_coeff],
cases h : degree p,
{
have : is_constant p,
{ rwa [is_constant_iff_degree_eq_zero] },
rcases this with ⟨a, ha⟩,
rw [ha, derivative_C],
simp
},
{ exact derivative_apply}
end
lemma derivative_eq_zero_iff_is_constant {p : polynomial α} (h : characteristic_zero α) :
(derivative p = 0) ↔ (is_constant p) :=
begin
constructor,
{
by_cases h1 : (p = 0),
{
intro h2,
simp *,
},
{
rw ←not_imp_not,
intros h2,
rw is_constant_iff_degree_eq_zero at h2,
have h3 : degree p ∈ support p,
from degree_mem_support_of_ne_zero h1,
rw mem_support_iff at h3,
have h4 : (derivative p) ((degree p)-1) = (degree p * (leading_coeff p)),
from derivative_degree_sub_one_eq_degree_mul_leading_coeff,
have h5 : (derivative p) (degree p - 1) ≠ 0,
{
rw h4,
apply mul_ne_zero,
apply h,
exact h2,
have h5 : leading_coeff p ≠ 0,
{
rw [←leading_coef_eq_zero_iff_eq_zero] at h1,
exact h1,
},
exact h5,
},
by_contradiction h6,
rw [h6, zero_apply] at h5,
contradiction
}
},
{
exact derivative_eq_zero_of_is_constant
}
end
end integral_domain
end polynomial |
48c778b22395287f9ea93bda4e8819e467f6898a | 0d7f5899c0475f9e105a439896d9377f80c0d7c3 | /src/.old/free_ralg.lean | e4ed901977144273fe6b6ae8bf96a1c265854641 | [] | no_license | adamtopaz/UnivAlg | 127038f320e68cdf3efcd0c084c9af02fdb8da3d | 2458d47a6e4fd0525e3a25b07cb7dd518ac173ef | refs/heads/master | 1,670,320,985,286 | 1,597,350,882,000 | 1,597,350,882,000 | 280,585,500 | 4 | 0 | null | 1,597,350,883,000 | 1,595,048,527,000 | Lean | UTF-8 | Lean | false | false | 1,428 | lean | import .lang
namespace ralg
universes v u
variables (L : lang.{v}) (S : Type u)
namespace free
inductive tp : Type (max v u)
| of : S → tp
| op {n} : L n → (fin n → tp) → tp
end free
def free : ralg L :=
{ carrier := free.tp L S,
appo := λ _ t as, free.tp.op t as }
namespace free
def univ : S → free L S := tp.of
variables (L) {S}
def lift {B : ralg L} (f : S → B) : (free L S) →% B :=
{ to_fn := λ t, tp.rec_on t f
(λ _ t _ bs, applyo t $ vector.of_fn bs),
applyo_map := λ n t as,
begin
have : as = vector.of_fn as, by rw vector.of_fn_to_fn,
conv_lhs {rw this},
rw vector.map_of_fn,
refl,
end }
theorem univ_comp_lift {B : ralg L} (f : S → B) : (lift _ f) ∘ (univ L S) = f := rfl
theorem lift_unique {B : ralg L} (f : S → B) (g : (free L S) →% B) :
g ∘ (univ _ _) = f → g = lift _ f := λ hyp,
begin
ext,
induction x with _ n t as h,
{ change (g ∘ (univ _ _)) x = _,
rw hyp, refl },
{ have : as = vector.of_fn as,
{ change _ = vector.to_fn _,
rw vector.to_fn_of_fn },
dsimp only [] at h,
rw this,
change g.to_fn (applyo _ _) = (lift _ f).to_fn (applyo _ _),
simp_rw ←ralgHom.applyo_map,
apply congr_arg,
simp only [vector.map_of_fn],
rw vector.eq_iff_to_fn_eq_to_fn,
funext,
change vector.to_fn _ _ = vector.to_fn _ _,
simp only [vector.to_fn_of_fn], apply h }
end
end free
end ralg |
4118bf5ce54238d6db3d30a050e905444b047d50 | 957a80ea22c5abb4f4670b250d55534d9db99108 | /tests/lean/caching_user_attribute.lean | 13f6af35f4bac96faed377906aa6bc306e9d1510 | [
"Apache-2.0"
] | permissive | GaloisInc/lean | aa1e64d604051e602fcf4610061314b9a37ab8cd | f1ec117a24459b59c6ff9e56a1d09d9e9e60a6c0 | refs/heads/master | 1,592,202,909,807 | 1,504,624,387,000 | 1,504,624,387,000 | 75,319,626 | 2 | 1 | Apache-2.0 | 1,539,290,164,000 | 1,480,616,104,000 | C++ | UTF-8 | Lean | false | false | 740 | lean | @[user_attribute]
meta def foo_attr : caching_user_attribute string :=
{ name := `foo, descr := "bar",
mk_cache := λ ns, return $ string.join (list.map (λ n, to_string n ++ "\n") ns),
dependencies := [] }
attribute [foo] eq.refl eq.mp
set_option trace.user_attributes_cache true
run_cmd do
s : string ← caching_user_attribute.get_cache foo_attr,
tactic.trace s,
s : string ← caching_user_attribute.get_cache foo_attr,
tactic.trace s,
tactic.set_basic_attribute `foo ``eq.mpr,
s : string ← caching_user_attribute.get_cache foo_attr,
tactic.trace s,
tactic.set_basic_attribute `reducible ``eq.mp, -- should not affect [foo] cache
s : string ← caching_user_attribute.get_cache foo_attr,
tactic.trace s
|
665a41f5428c97df9f51158f13f6f83c9777e11b | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/category_theory/functor/functorial.lean | 7df2a37790e8775b0166918f13e7bdee495b6cce | [
"Apache-2.0"
] | permissive | leanprover-community/mathlib | 56a2cadd17ac88caf4ece0a775932fa26327ba0e | 442a83d738cb208d3600056c489be16900ba701d | refs/heads/master | 1,693,584,102,358 | 1,693,471,902,000 | 1,693,471,902,000 | 97,922,418 | 1,595 | 352 | Apache-2.0 | 1,694,693,445,000 | 1,500,624,130,000 | Lean | UTF-8 | Lean | false | false | 2,661 | lean | /-
Copyright (c) 2019 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import category_theory.functor.basic
/-!
# Unbundled functors, as a typeclass decorating the object-level function.
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
-/
namespace category_theory
-- declare the `v`'s first; see `category_theory.category` for an explanation
universes v v₁ v₂ v₃ u u₁ u₂ u₃
variables {C : Type u₁} [category.{v₁} C] {D : Type u₂} [category.{v₂} D]
/-- A unbundled functor. -/
-- Perhaps in the future we could redefine `functor` in terms of this, but that isn't the
-- immediate plan.
class functorial (F : C → D) : Type (max v₁ v₂ u₁ u₂) :=
(map : Π {X Y : C}, (X ⟶ Y) → ((F X) ⟶ (F Y)))
(map_id' : ∀ (X : C), map (𝟙 X) = 𝟙 (F X) . obviously)
(map_comp' : ∀ {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z), map (f ≫ g) = (map f) ≫ (map g) . obviously)
/--
If `F : C → D` (just a function) has `[functorial F]`,
we can write `map F f : F X ⟶ F Y` for the action of `F` on a morphism `f : X ⟶ Y`.
-/
def map (F : C → D) [functorial.{v₁ v₂} F] {X Y : C} (f : X ⟶ Y) : F X ⟶ F Y :=
functorial.map.{v₁ v₂} f
@[simp] lemma map_as_map {F : C → D} [functorial.{v₁ v₂} F] {X Y : C} {f : X ⟶ Y} :
functorial.map.{v₁ v₂} f = map F f := rfl
@[simp] lemma functorial.map_id {F : C → D} [functorial.{v₁ v₂} F] {X : C} :
map F (𝟙 X) = 𝟙 (F X) := functorial.map_id' X
@[simp] lemma functorial.map_comp
{F : C → D} [functorial.{v₁ v₂} F] {X Y Z : C} {f : X ⟶ Y} {g : Y ⟶ Z} :
map F (f ≫ g) = map F f ≫ map F g := functorial.map_comp' f g
namespace functor
/--
Bundle a functorial function as a functor.
-/
def of (F : C → D) [I : functorial.{v₁ v₂} F] : C ⥤ D :=
{ obj := F,
..I }
end functor
instance (F : C ⥤ D) : functorial.{v₁ v₂} (F.obj) := { .. F }
@[simp]
lemma map_functorial_obj (F : C ⥤ D) {X Y : C} (f : X ⟶ Y) : map F.obj f = F.map f := rfl
instance functorial_id : functorial.{v₁ v₁} (id : C → C) :=
{ map := λ X Y f, f }
section
variables {E : Type u₃} [category.{v₃} E]
/--
`G ∘ F` is a functorial if both `F` and `G` are.
-/
-- This is no longer viable as an instance in Lean 3.7,
-- #lint reports an instance loop
-- Will this be a problem?
def functorial_comp (F : C → D) [functorial.{v₁ v₂} F] (G : D → E) [functorial.{v₂ v₃} G] :
functorial.{v₁ v₃} (G ∘ F) :=
{ ..(functor.of F ⋙ functor.of G) }
end
end category_theory
|
cb6e2a8f8a5b95cb56749678792a91de8b19ac82 | ebbdcbd7ddc89a9ef7c3b397b301d5f5272a918f | /qp/p1_categories/c5_leancat/s1_basic.lean | d47e5168efe69d06e166332a9fac96783ebe6c52 | [] | no_license | intoverflow/qvr | 34b9ef23604738381ca20b7d622fd0399d88f2dd | 0cfcd33fe4bf8d93851a00cec5bfd21e77105d74 | refs/heads/master | 1,616,591,570,371 | 1,492,575,772,000 | 1,492,575,772,000 | 80,061,627 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 24,917 | lean | /- -----------------------------------------------------------------------
Basic properties of LeanCat.
----------------------------------------------------------------------- -/
import ..c1_basic
import ..c2_limits
import ..c3_wtypes
import ..c4_topoi
namespace qp
open stdaux
universe variables ℓ' ℓ ℓobj ℓhom
/- -----------------------------------------------------------------------
Constant homs.
----------------------------------------------------------------------- -/
/-! #brief A constant hom in LeanCat.
-/
definition LeanCat.const_hom
{X Y : LeanCat.{ℓ}^.obj}
(y : Y)
: LeanCat^.hom X Y
| x := y
/- -----------------------------------------------------------------------
Limits and colimits.
----------------------------------------------------------------------- -/
/-! #brief LeanCat has all limits.
-/
instance LeanCat.HasAllLimits : HasAllLimits.{ℓobj ℓhom} LeanCat.{max ℓ ℓobj}
:= { has_limit
:= λ X L
, HasLimit.show
{ g : ∀ (x : X^.obj), L^.obj x
// ∀ {x₁ x₂ : X^.obj} (f : X^.hom x₁ x₂)
, g x₂ = L^.hom f (g x₁)
}
(λ x g, g^.val x)
(λ x₁ x₂ f, funext (λ g, g^.property f))
(λ C hom ωhom c
, { val := λ x, hom x c
, property := λ x₁ x₂ f, begin rw ωhom f, trivial end
})
(λ C hom ωhom x, rfl)
(λ C hom ωhom f ωf
, funext (λ c, subtype.eq (funext (λ x, eq.symm (by apply congr_fun (ωf x) c)))))
}
/-! #brief The equivalence relation underlying colimits in LeanCat.
-/
definition LeanCat.HasAllCoLimits.prop {X : Cat.{ℓobj ℓhom}}
(L : Fun X LeanCat.{max ℓ ℓobj})
(a b : (Σ (x : X^.obj), L^.obj x))
: Prop
:= ∃ (f : X^.hom a^.fst b^.fst), b^.snd = L^.hom f a^.snd
/-! #brief LeanCat has all co-limits.
-/
instance LeanCat.HasAllCoLimits : HasAllCoLimits.{ℓobj ℓhom} LeanCat.{max ℓ ℓobj}
:= { has_colimit
:= λ X L
, HasCoLimit.show
(quot (LeanCat.HasAllCoLimits.prop L))
(λ x Lx, quot.mk _ {fst := x, snd := Lx})
(λ x₁ x₂ f, funext (λ Lx, quot.sound (exists.intro f rfl)))
(λ C hom ωhom
, let f : (Σ (x : X^.obj), L^.obj x) → C
:= λ Lx, hom Lx^.fst Lx^.snd in
let ωf : ∀ (a b : Σ (x : ⟦X⟧), L^.obj x)
, LeanCat.HasAllCoLimits.prop L a b
→ f a = f b
:= λ a b ωab
, begin
dsimp,
cases ωab with g ωg,
rw [ωg, ωhom g],
trivial
end
in quot.lift f ωf)
(λ C hom ωhom x, rfl)
(λ C hom ωhom f ωf
, funext (quot.ind (begin
intro Lx,
cases Lx with x Lx,
apply eq.symm (congr_fun (ωf x) Lx)
end)))
}
/- -----------------------------------------------------------------------
Limits and colimits in over/under categories.
----------------------------------------------------------------------- -/
/-! #brief Structure hom for colimits in OverCat LeanCat.
-/
definition LeanCat.Over.HasCoLimit.colim_hom
(B : LeanCat.{max ℓ ℓobj}^.obj)
{X : Cat.{ℓobj ℓhom}}
(L : Fun X (OverCat LeanCat B))
: LeanCat^.hom (colimit (OverFun.out LeanCat B □□ L)) B
:= let f : (Σ (x : X^.obj), (L^.obj x)^.obj) → B
:= λ x, (L^.obj x^.fst)^.hom x^.snd
in quot.lift f
begin
intros a b,
cases a with xa a,
cases b with xb b,
intro ω, cases ω with h ωb,
dsimp at h,
dsimp at ωb, subst ωb,
apply congr_fun (L^.hom h)^.triangle a
end
/-! #brief OverCat LeanCat has all co-limits.
-/
instance LeanCat.Over.HasCoLimit
(B : LeanCat.{max ℓ ℓobj}^.obj)
{X : Cat.{ℓobj ℓhom}} (L : Fun X (OverCat LeanCat B))
: HasCoLimit L
:= HasCoLimit.show
{ obj := colimit (OverFun.out LeanCat B □□ L)
, hom := LeanCat.Over.HasCoLimit.colim_hom B L
}
(λ x, { hom := λ Lx, quot.mk _ { fst := x, snd := Lx }
, triangle := sorry
})
(λ x₁ x₂ f, begin
apply OverHom.eq,
apply funext, intro Lx,
apply quot.sound,
apply exists.intro f,
trivial
end)
sorry
sorry
sorry
instance LeanCat.Over.HasAllCoLimits
(B : LeanCat.{max ℓ ℓobj}^.obj)
: HasAllCoLimits.{ℓobj ℓhom}
(OverCat LeanCat.{max ℓ ℓobj} B)
:= { has_colimit := @LeanCat.Over.HasCoLimit B
}
/-! #brief Handy simplifier.
-/
theorem LeanCat.Over.HasCoLimit.obj
(B : LeanCat.{max ℓ ℓobj}^.obj)
{X : Cat.{ℓobj ℓhom}} (L : Fun X (OverCat LeanCat B))
: (colimit L)^.obj = colimit (OverFun.out LeanCat B □□ L)
:= rfl
/- -----------------------------------------------------------------------
Products.
----------------------------------------------------------------------- -/
/-! #brief LeanCat has all products.
-/
instance LeanCat.HasProduct
{A : Type ℓ'} (factor : A → LeanCat.{max ℓ ℓ'}^.obj)
: HasProduct LeanCat.{max ℓ ℓ'} factor
:= HasProduct.show LeanCat factor
(∀ (a : A), factor a)
(λ a fa, fa a)
(λ T f t a, f a t)
(λ T f a, rfl)
(λ T f h ωh
, begin
apply funext, intro t,
apply funext, intro a,
rw ωh,
trivial
end)
/-! #brief LeanCat has all products.
-/
instance LeanCat.HasAllProducts
: HasAllProducts.{ℓ'} LeanCat.{max ℓ ℓ'}
:= { has_product := @LeanCat.HasProduct
}
/-! #brief Finite product type in LeanCat.
-/
definition ListProd
: ∀ (TT : list LeanCat.{ℓ}^.obj)
, LeanCat.{ℓ}^.obj
| [] := punit
| [T] := T
| (T :: TT) := T × ListProd TT
/-! #brief A fancy way of mapping through a ListProd.
-/
definition {ℓb ℓx ℓy} ListProd.map
{Ba : Type ℓb} {Tx : Ba → Type ℓx} {Ty : Ba → Type ℓy}
(f : ∀ (b : Ba), Tx b → Ty b)
: ∀ (BB : list Ba)
, ListProd (list.map Tx BB)
→ ListProd (list.map Ty BB)
| [] _ := punit.star
| [Ba] x := f Ba x
| (Ba :: Ba₀ :: BB) (prod.mk x xx) := (f Ba x, @ListProd.map (Ba₀ :: BB) xx)
/-! #brief Projection from finite product type in LeanCat.
-/
definition ListProd.π
: ∀ (TT : list LeanCat.{ℓ}^.obj)
(n : fin (list.length TT))
(x : ListProd TT)
, list.get TT n
| [] n x := fin.zero_elim n
| [T] (fin.mk 0 ω0) X := X
| [T] (fin.mk (nat.succ n) ωn) X := false.rec _ begin cases ωn, cases a end
| (T :: T₁ :: TT) (fin.mk 0 ω0) X := X^.fst
| (T :: T₁ :: TT) (fin.mk (nat.succ n) ωn) X := ListProd.π (T₁ :: TT) { val := n, is_lt := nat.lt_of_succ_lt_succ ωn } X^.snd
/-! #brief Enumerating a map into a finite product.
-/
definition ListProd.univ
: ∀ (TT : list LeanCat.{ℓ}^.obj)
(S : LeanCat.{ℓ}^.obj)
(f : ∀ (n : ℕ)
(ωn : n < list.length TT)
, S → list.get TT { val := n, is_lt := ωn })
, S → ListProd TT
| [] S f s := punit.star
| [T] S f s := f 0 (fin_of 0)^.is_lt s
| (T :: T₁ :: TT) S f s
:= ( f 0 (fin_of 0)^.is_lt s
, ListProd.univ (T₁ :: TT) S (λ n ωn s', f (nat.succ n) (nat.succ_lt_succ ωn) s') s
)
/-! #brief Factoring property of the universal map.
-/
definition ListProd.univ.factor
: ∀ {TT : list LeanCat.{ℓ}^.obj}
{S : LeanCat.{ℓ}^.obj}
{f : ∀ (n : ℕ)
(ωn : n < list.length TT)
, S → list.get TT { val := n, is_lt := ωn }}
{n : ℕ} {ωn : n < list.length TT}
{s : S}
, f n ωn s = ListProd.π TT
{ val := n, is_lt := ωn }
(ListProd.univ TT S f s)
| [] S f n ωn s := by cases ωn
| [T] S f 0 ω0 s := rfl
| [T] S f (nat.succ n) ωn s := false.rec _ begin cases ωn, cases a end
| (T :: T₁ :: TT) S f 0 ω0 s := rfl
| (T :: T₁ :: TT) S f (nat.succ n) ωn s
:= begin
refine eq.trans _ (@ListProd.univ.factor (T₁ :: TT) S _ n _ s),
trivial
end
/-! #brief LeanCat has all finite products.
-/
instance LeanCat.HasFinProduct (factor : list LeanCat.{ℓ}^.obj)
: HasFinProduct LeanCat factor
:= HasProduct.show LeanCat (list.get factor)
(ListProd factor)
(ListProd.π factor)
(λ T f, ListProd.univ factor T (λ n ωn, f { val := n, is_lt := ωn }))
(λ T f n
, begin
apply funext, intro t,
cases n with n ωn,
refine eq.trans _ (ListProd.univ.factor),
trivial
end)
(λ T f h ωh
, begin
assert ωf : f = λ n t, ListProd.π factor n (h t),
{ apply funext @ωh },
subst ωf,
apply funext, intro t,
induction factor with T factor rec,
{ apply punit.uniq },
cases factor with T₁ factor,
{ trivial },
{ apply prod.eq,
{ trivial },
{ refine eq.trans _ (rec (λ t, (h t)^.snd) _),
{ trivial },
{ intro n, trivial }
}
}
end)
/-! #brief LeanCat has all finite products.
-/
instance LeanCat.HasAllFinProducts
: HasAllFinProducts LeanCat.{ℓ}
:= { has_product := LeanCat.HasFinProduct
}
/- -----------------------------------------------------------------------
Co-products.
----------------------------------------------------------------------- -/
/-! #brief LeanCat has all co-products.
-/
instance LeanCat.HasCoProduct
{A : Type ℓ'} (factor : A → LeanCat.{max ℓ ℓ'}^.obj)
: HasCoProduct LeanCat.{max ℓ ℓ'} factor
:= HasCoProduct.show LeanCat factor
(Σ (a : A), factor a)
(sigma.mk)
(λ T f af, f af^.fst af^.snd)
(λ T f a, rfl)
(λ T f h ωh
, begin
apply funext, intro af,
cases af with a f,
rw ωh,
trivial
end)
/-! #brief LeanCat has all co-products.
-/
instance LeanCat.HasAllCoProducts
: HasAllCoProducts.{ℓ'} LeanCat.{max ℓ ℓ'}
:= { has_coproduct := @LeanCat.HasCoProduct
}
/-! #brief Finite sum type in LeanCat.
-/
definition ListSum
: ∀ (TT : list LeanCat.{ℓ}^.obj)
, LeanCat.{ℓ}^.obj
| [] := pempty
| [T] := T
| (T :: TT) := sum T (ListSum TT)
/-! #brief A fancy way of mapping through a ListSum.
-/
definition {ℓb ℓx ℓy} ListSum.map
{Ba : Type ℓb} {Tx : Ba → Type ℓx} {Ty : Ba → Type ℓy}
: ∀ (BB : list Ba)
(f : ∀ (n : ℕ) (ωn : n < list.length BB)
, Tx (list.get BB {val := n, is_lt := ωn}) → Ty (list.get BB {val := n, is_lt := ωn}))
, ListSum (list.map Tx BB)
→ ListSum (list.map Ty BB)
| [] f e := by cases e
| [Ba] f x := f 0 fin.zero^.is_lt x
| (Ba :: Ba₀ :: BB) f (sum.inl x) := sum.inl (f 0 fin.zero^.is_lt x)
| (Ba :: Ba₀ :: BB) f (sum.inr xx)
:= sum.inr (ListSum.map (Ba₀ :: BB)
(λ n ωn, f (nat.succ n) (nat.succ_le_succ ωn))
xx)
/-! #brief Inclusion into finite sum type in LeanCat.
-/
definition ListSum.ι
: ∀ (TT : list LeanCat.{ℓ}^.obj)
(n : fin (list.length TT))
(x : list.get TT n)
, ListSum TT
| [] n x := fin.zero_elim n
| [T] (fin.mk 0 ω0) x := x
| [T] (fin.mk (nat.succ n) ωn) x := false.rec _ begin cases ωn, cases a end
| (T :: T₁ :: TT) (fin.mk 0 ω0) x := sum.inl x
| (T :: T₁ :: TT) (fin.mk (nat.succ n) ωn) x
:= sum.inr (ListSum.ι (T₁ :: TT) { val := n, is_lt := nat.lt_of_succ_lt_succ ωn } x)
/-! #brief Enumerating a map out of a finite sum.
-/
definition ListSum.univ
: ∀ (TT : list LeanCat.{ℓ}^.obj)
(S : LeanCat.{ℓ}^.obj)
(f : ∀ (n : ℕ)
(ωn : n < list.length TT)
, list.get TT { val := n, is_lt := ωn } → S)
, ListSum TT → S
| [] S f e := by cases e
| [T] S f s := f 0 (fin_of 0)^.is_lt s
| (T :: T₁ :: TT) S f (sum.inl s)
:= f 0 (fin_of 0)^.is_lt s
| (T :: T₁ :: TT) S f (sum.inr s)
:= ListSum.univ (T₁ :: TT) S (λ n ωn s', f (nat.succ n) (nat.succ_lt_succ ωn) s') s
/-! #brief Factoring property of the universal map.
-/
definition ListSum.univ.factor
: ∀ {TT : list LeanCat.{ℓ}^.obj}
{S : LeanCat.{ℓ}^.obj}
{f : ∀ (n : ℕ)
(ωn : n < list.length TT)
, list.get TT { val := n, is_lt := ωn } → S}
{n : ℕ} {ωn : n < list.length TT}
{s : list.get TT { val := n, is_lt := ωn }}
, f n ωn s = ListSum.univ TT S f
(ListSum.ι TT { val := n, is_lt := ωn } s)
| [] S f n ωn s := by cases ωn
| [T] S f 0 ω0 s := rfl
| [T] S f (nat.succ n) ωn s := false.rec _ begin cases ωn, cases a end
| (T :: T₁ :: TT) S f 0 ω0 s := rfl
| (T :: T₁ :: TT) S f (nat.succ n) ωn s
:= begin
refine eq.trans _ (@ListSum.univ.factor (T₁ :: TT) S _ n _ s),
trivial
end
/-! #brief LeanCat has all finite products.
-/
instance LeanCat.HasFinCoProduct (factor : list LeanCat.{ℓ}^.obj)
: HasFinCoProduct LeanCat factor
:= HasCoProduct.show LeanCat (list.get factor)
(ListSum factor)
(ListSum.ι factor)
(λ T f, ListSum.univ factor T (λ n ωn, f { val := n, is_lt := ωn }))
(λ T f n
, begin
apply funext, intro t,
cases n with n ωn,
refine eq.trans _ (ListSum.univ.factor),
trivial
end)
(λ T f h ωh
, begin
assert ωf : f = λ n t, h (ListSum.ι factor n t),
{ apply funext @ωh },
subst ωf,
apply funext, intro t,
induction factor with T factor rec,
{ cases t },
cases factor with T₁ factor,
{ trivial },
{ cases t,
{ trivial },
{ refine eq.trans _ (rec (λ a, (h (sum.inr a))) _ _),
{ trivial },
{ intro n, trivial }
}
}
end)
/-! #brief LeanCat has all finite products.
-/
instance LeanCat.HasAllFinCoProducts
: HasAllFinCoProducts LeanCat.{ℓ}
:= { has_coproduct := LeanCat.HasFinCoProduct
}
/- -----------------------------------------------------------------------
Pullbacks.
----------------------------------------------------------------------- -/
/-! #brief LeanCat has all pullbacks.
-/
instance LeanCat.HasPullback
{base : LeanCat.{ℓ}^.obj} {factor : list LeanCat.{ℓ}^.obj}
{T : LeanCat.{ℓ}^.obj}
(maps : @HomsIn LeanCat (base :: factor) T)
: HasPullback LeanCat maps
:= HasPullback.show LeanCat.{ℓ} maps
{ p : finproduct LeanCat (base :: factor)
// ∀ (n : fin (list.length (base :: factor)))
, HomsIn.get maps (fin_of 0) (finproduct.π LeanCat (base :: factor) (fin_of 0) p)
= HomsIn.get maps n (finproduct.π LeanCat (base :: factor) n p)
}
(λ p, HomsIn.get maps (fin_of 0) (finproduct.π LeanCat (base :: factor) (fin_of 0) p^.val))
(HomsOut.comp (finproduct.cone LeanCat (base :: factor))^.Proj (λ p, p^.val))
begin
cases maps with _ m_base _ maps,
-- apply HomsList.eq,
-- { trivial },
-- induction maps with _ m₁ _ maps rec,
-- { trivial },
exact sorry
end
sorry
sorry
sorry
instance LeanCat.HasAllPullbacks
: HasAllPullbacks LeanCat.{ℓ}
:= { has_pullback
:= λ base factor T maps
, LeanCat.HasPullback maps
}
/-! #brief A handy wrapper.
-/
definition LeanCat.BaseChangeFun
{X Y : LeanCat.{ℓ}^.obj}
(f : LeanCat.{ℓ}^.hom X Y)
: Fun (OverCat LeanCat Y) (OverCat LeanCat X)
:= @BaseChangeFun LeanCat X Y f
(HasAllPullbacks.HasPullbacksAlong LeanCat f)
/- -----------------------------------------------------------------------
Products in OverCat LeanCat.
----------------------------------------------------------------------- -/
/-! #brief OverCat LeanCat has finite products.
-/
instance LeanCat.Over.HasFinProduct
(T₀ : LeanCat.{ℓ}^.obj)
(factor : list (OverCat LeanCat T₀)^.obj)
: HasFinProduct (OverCat LeanCat T₀) factor
:= OverCat.HasFinProduct LeanCat.{ℓ} T₀ factor
/- -----------------------------------------------------------------------
Exponentials.
----------------------------------------------------------------------- -/
/-! #brief LeanCat has exponential objects.
-/
instance LeanCat.HasExp (X Y : LeanCat.{ℓ}^.obj)
: @HasExp LeanCat X Y
:= { exp := Y → X
, ev
:= λ exp_Y_HasFinProduct p
, let f := @finproduct.π _ _ exp_Y_HasFinProduct (@fin_of 1 0)
in let y := @finproduct.π _ _ exp_Y_HasFinProduct (@fin_of 0 1)
in f p (y p)
, univ
:= λ Z Z_Y_HasFinProduct e z y
, e (finproduct.iso (LeanCat.HasFinProduct [Z, Y]) Z_Y_HasFinProduct (z, y))
, factor := λ exp_Y_HasFinProduct Z Z_Y_HasFinProduct e
, begin
apply funext, intro zy,
rw LeanCat.simp_circ,
dsimp,
exact sorry
end
, uniq := λ exp_Y_HasFinProduct Z Z_Y_HasFinProduct e u ωu
, begin
apply funext, intro z,
apply funext, intro y,
rw ωu,
exact sorry
end
}
/- -----------------------------------------------------------------------
Exponentials in OverCat LeanCat.
----------------------------------------------------------------------- -/
/-! #brief LeanCat has exponential objects.
-/
definition LeanCat.Over.exp
(T₀ : LeanCat.{ℓ}^.obj)
(T S : (OverCat LeanCat T₀)^.obj)
: OverObj LeanCat.{ℓ} T₀
:= { obj := Σ (t₀ : T₀)
, {s : S^.dom // S^.hom s = t₀}
→ {t : T^.obj // T^.hom t = t₀}
, hom := sigma.fst
}
/-! #brief LeanCat has exponential objects.
-/
instance LeanCat.Over.HasExp
(T₀ : LeanCat.{ℓ}^.obj)
(X Y : (OverCat LeanCat T₀)^.obj)
: @HasExp (OverCat LeanCat T₀) X Y
:= { exp := LeanCat.Over.exp T₀ X Y
, ev
:= λ p_HasProd
, { hom := λ p, let f := (@finproduct.π (OverCat LeanCat T₀) [LeanCat.Over.exp T₀ X Y, Y] p_HasProd (@fin_of 1 0))^.hom p
in let y := (@finproduct.π (OverCat LeanCat T₀) [LeanCat.Over.exp T₀ X Y, Y] p_HasProd (@fin_of 0 1))^.hom p
in (f^.snd { val := y, property := sorry })^.val
, triangle := sorry
}
, univ
:= λ A A_HasProd f
, let a_y : ∀ (a : A^.obj)
(y : {s // Y^.hom s = A^.hom a})
, OverObj.dom (finproduct (OverCat LeanCat T₀) [A, Y])
:= λ a y
, { val := (a, y^.val)
, property
:= begin
intro nωn, cases nωn with n ωn,
cases n with n, { trivial },
cases n with n, { apply eq.symm y^.property },
apply nat.not_lt_add_right n 2 ωn
end
}
in let a_y' := λ a y, ((finproduct.iso (LeanCat.Over.HasFinProduct T₀ [A, Y]) A_HasProd)^.hom (a_y a y))
in { hom
:= λ a
, ⟨ A^.hom a
, λ y, { val := f^.hom (a_y' a y)
, property := begin
refine eq.trans (congr_fun (eq.symm f^.triangle) (a_y' a y)) _,
exact sorry
end
}
⟩
, triangle := sorry
}
, factor := λ A p_HasProd A_HasProd e
, sorry
, uniq := λ exp_Y_HasFinProduct Z Z_Y_HasFinProduct e u ωu
, sorry
}
/-! #brief OverCat LeanCat has all exponentials.
-/
instance LeanCat.Over.HasAllExp
(T₀ : LeanCat.{ℓ}^.obj)
: @HasAllExp (OverCat LeanCat T₀)
:= { has_exp := LeanCat.Over.HasExp T₀
}
/-! #brief LeanCat has exponentials in all slices.
-/
instance LeanCat.HasAllLocalExp
: HasAllLocalExp LeanCat.{ℓ}
:= { has_exp := LeanCat.Over.HasExp
}
/- -----------------------------------------------------------------------
Subobject classifiers.
----------------------------------------------------------------------- -/
/-! #brief Axiom of choice gives LeanCat a subobject classifier.
-/
noncomputable instance LeanCat.HasSubobjClass
: HasSubobjClass LeanCat.{ℓ}
:= HasSubobjClass.show
(λ LeanCat_HasFinal, Lean.LevelMax Prop)
(λ LeanCat_HasFinal, λ u, Lean.LevelMax.lift true)
(λ LeanCat_HasFinal U X m m_Monic, λ x, Lean.LevelMax.lift (∃ (u : U), m u = x))
(λ LeanCat_HasFinal U X V m m_Monic h ωh x
, let u₀ : ∃ (u : U), m u = h x
:= begin
apply of_iff_true,
apply eq.to_iff,
apply Lean.LevelMax.lift.inj,
apply congr_fun ωh
end in
let u : ∃! (u : U), h x = m u
:= exists.elim u₀
(λ u ωu
, exists_unique.intro u (eq.symm ωu)
(λ u' ωu', LeanCat.Monic.inj m_Monic
(eq.symm (eq.trans ωu ωu'))))
in unique_choice u)
(λ LeanCat_HasFinal U X m m_Monic
, begin
apply funext, intro u,
apply congr_arg Lean.LevelMax.lift,
apply iff.to_eq,
apply iff_true_intro,
apply exists.intro u,
trivial
end)
(λ LeanCat_HasFinal U V X m m_Monic h ωh
, begin
apply funext, intro v,
dsimp, unfold LeanCat SortCat, dsimp,
generalize (of_iff_true (eq.to_iff (Lean.LevelMax.lift.inj (congr_fun ωh v)))) ω,
intro ω, cases ω with u ωu,
refine eq.trans (eq.symm _) (eq.symm (congr_arg m unique_choice.simp)),
exact ωu
end)
(λ LeanCat_HasFinal U V X m m_Monic h ωh
, begin
apply funext, intro v,
generalize (of_iff_true (eq.to_iff (Lean.LevelMax.lift.inj (congr_fun ωh v)))) ω,
intro ω, cases ω with u ωu,
refine eq.trans _ (eq.symm unique_choice.simp),
apply LeanCat.Monic.inj m_Monic,
exact eq.symm ωu
end)
(λ LeanCat_HasFinal U X m m_Monic char' char'_IsPullback
, sorry)
-- , char_uniq
-- := λ LeanCat_HasFinal U X m m_Monic char' ωchar'
-- , let char'' : X → Prop
-- := λ x, Lean.LevelMax.cases_on (char' x) (λ P, P)
-- in begin
-- apply funext, intro x,
-- assert ωchar'' : char' x = Lean.LevelMax.lift (Lean.LevelMax.cases_on (char' x) (λ P, P)),
-- { generalize (char' x) char'_x,
-- intro char'_x, cases char'_x,
-- trivial,
-- },
-- refine eq.trans ωchar'' (congr_arg Lean.LevelMax.lift _),
-- apply iff.to_eq,
-- apply iff.intro,
-- { intro ωP_x, exact sorry
-- },
-- { intro ωu, cases ωu with u ωu,
-- subst ωu,
-- -- true because ωchar' implies char' (m u) = Lean.LevelMax.lift true.
-- exact sorry
-- }
-- end
-- }
/- -----------------------------------------------------------------------
Natural numbers object.
----------------------------------------------------------------------- -/
/-! #brief LeanCat has an NNO.
-/
instance LeanCat.HasNNO
: @HasNNO LeanCat.{ℓ} LeanCat.HasFinal
:= { nn := Lean.LevelMax ℕ
, zero := λ u, Lean.LevelMax.lift 0
, succ := Lean.LevelMax.map nat.succ
, univ := λ A z s n, nat.rec_on (Lean.LevelMax.unlift n)
(z punit.star)
(λ n' a, s a)
, comm_zero
:= λ A z s
, begin
apply funext, intro u, cases u,
trivial
end
, comm_succ
:= λ A z s
, begin
apply funext, intro n, cases n with n,
induction n with n rec,
{ trivial },
{ apply congr_arg s,
apply rec
}
end
, uniq
:= λ A z s u' ωzero ωsucc
, begin
apply funext, intro n, cases n with n,
induction n with n rec,
{ rw ωzero, trivial },
{ refine eq.trans (eq.symm (congr_fun ωsucc (Lean.LevelMax.lift n))) _,
apply congr_arg s rec
}
end
}
end qp
|
69484e7080c67dd6ecad940e8429d52c71552918 | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/category_theory/limits/constructions/zero_objects.lean | c33665cd1669523537a7a8f01d415a5e29fa0975 | [
"Apache-2.0"
] | permissive | alreadydone/mathlib | dc0be621c6c8208c581f5170a8216c5ba6721927 | c982179ec21091d3e102d8a5d9f5fe06c8fafb73 | refs/heads/master | 1,685,523,275,196 | 1,670,184,141,000 | 1,670,184,141,000 | 287,574,545 | 0 | 0 | Apache-2.0 | 1,670,290,714,000 | 1,597,421,623,000 | Lean | UTF-8 | Lean | false | false | 7,142 | lean | /-
Copyright (c) 2022 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import category_theory.limits.shapes.pullbacks
import category_theory.limits.shapes.zero_morphisms
import category_theory.limits.constructions.binary_products
/-!
# Limits involving zero objects
Binary products and coproducts with a zero object always exist,
and pullbacks/pushouts over a zero object are products/coproducts.
-/
noncomputable theory
open category_theory
variables {C : Type*} [category C]
namespace category_theory.limits
variables [has_zero_object C] [has_zero_morphisms C]
open_locale zero_object
/-- The limit cone for the product with a zero object. -/
def binary_fan_zero_left (X : C) : binary_fan (0 : C) X :=
binary_fan.mk 0 (𝟙 X)
/-- The limit cone for the product with a zero object is limiting. -/
def binary_fan_zero_left_is_limit (X : C) : is_limit (binary_fan_zero_left X) :=
binary_fan.is_limit_mk (λ s, binary_fan.snd s) (by tidy) (by tidy) (by tidy)
instance has_binary_product_zero_left (X : C) : has_binary_product (0 : C) X :=
has_limit.mk ⟨_, binary_fan_zero_left_is_limit X⟩
/-- A zero object is a left unit for categorical product. -/
def zero_prod_iso (X : C) : (0 : C) ⨯ X ≅ X :=
limit.iso_limit_cone ⟨_, binary_fan_zero_left_is_limit X⟩
@[simp] lemma zero_prod_iso_hom (X : C) : (zero_prod_iso X).hom = prod.snd :=
rfl
@[simp] lemma zero_prod_iso_inv_snd (X : C) : (zero_prod_iso X).inv ≫ prod.snd = 𝟙 X :=
by { dsimp [zero_prod_iso, binary_fan_zero_left], simp, }
/-- The limit cone for the product with a zero object. -/
def binary_fan_zero_right (X : C) : binary_fan X (0 : C) :=
binary_fan.mk (𝟙 X) 0
/-- The limit cone for the product with a zero object is limiting. -/
def binary_fan_zero_right_is_limit (X : C) : is_limit (binary_fan_zero_right X) :=
binary_fan.is_limit_mk (λ s, binary_fan.fst s) (by tidy) (by tidy) (by tidy)
instance has_binary_product_zero_right (X : C) : has_binary_product X (0 : C) :=
has_limit.mk ⟨_, binary_fan_zero_right_is_limit X⟩
/-- A zero object is a right unit for categorical product. -/
def prod_zero_iso (X : C) : X ⨯ (0 : C) ≅ X :=
limit.iso_limit_cone ⟨_, binary_fan_zero_right_is_limit X⟩
@[simp] lemma prod_zero_iso_hom (X : C) : (prod_zero_iso X).hom = prod.fst :=
rfl
@[simp] lemma prod_zero_iso_iso_inv_snd (X : C) : (prod_zero_iso X).inv ≫ prod.fst = 𝟙 X :=
by { dsimp [prod_zero_iso, binary_fan_zero_right], simp, }
/-- The colimit cocone for the coproduct with a zero object. -/
def binary_cofan_zero_left (X : C) : binary_cofan (0 : C) X :=
binary_cofan.mk 0 (𝟙 X)
/-- The colimit cocone for the coproduct with a zero object is colimiting. -/
def binary_cofan_zero_left_is_colimit (X : C) : is_colimit (binary_cofan_zero_left X) :=
binary_cofan.is_colimit_mk (λ s, binary_cofan.inr s) (by tidy) (by tidy) (by tidy)
instance has_binary_coproduct_zero_left (X : C) : has_binary_coproduct (0 : C) X :=
has_colimit.mk ⟨_, binary_cofan_zero_left_is_colimit X⟩
/-- A zero object is a left unit for categorical coproduct. -/
def zero_coprod_iso (X : C) : (0 : C) ⨿ X ≅ X :=
colimit.iso_colimit_cocone ⟨_, binary_cofan_zero_left_is_colimit X⟩
@[simp] lemma inr_zero_coprod_iso_hom (X : C) : coprod.inr ≫ (zero_coprod_iso X).hom = 𝟙 X :=
by { dsimp [zero_coprod_iso, binary_cofan_zero_left], simp, }
@[simp] lemma zero_coprod_iso_inv (X : C) : (zero_coprod_iso X).inv = coprod.inr :=
rfl
/-- The colimit cocone for the coproduct with a zero object. -/
def binary_cofan_zero_right (X : C) : binary_cofan X (0 : C) :=
binary_cofan.mk (𝟙 X) 0
/-- The colimit cocone for the coproduct with a zero object is colimiting. -/
def binary_cofan_zero_right_is_colimit (X : C) : is_colimit (binary_cofan_zero_right X) :=
binary_cofan.is_colimit_mk (λ s, binary_cofan.inl s) (by tidy) (by tidy) (by tidy)
instance has_binary_coproduct_zero_right (X : C) : has_binary_coproduct X (0 : C) :=
has_colimit.mk ⟨_, binary_cofan_zero_right_is_colimit X⟩
/-- A zero object is a right unit for categorical coproduct. -/
def coprod_zero_iso (X : C) : X ⨿ (0 : C) ≅ X :=
colimit.iso_colimit_cocone ⟨_, binary_cofan_zero_right_is_colimit X⟩
@[simp] lemma inr_coprod_zeroiso_hom (X : C) : coprod.inl ≫ (coprod_zero_iso X).hom = 𝟙 X :=
by { dsimp [coprod_zero_iso, binary_cofan_zero_right], simp, }
@[simp] lemma coprod_zero_iso_inv (X : C) : (coprod_zero_iso X).inv = coprod.inl :=
rfl
instance has_pullback_over_zero
(X Y : C) [has_binary_product X Y] : has_pullback (0 : X ⟶ 0) (0 : Y ⟶ 0) :=
has_limit.mk ⟨_, is_pullback_of_is_terminal_is_product _ _ _ _
has_zero_object.zero_is_terminal (prod_is_prod X Y)⟩
/-- The pullback over the zeron object is the product. -/
def pullback_zero_zero_iso (X Y : C) [has_binary_product X Y] :
pullback (0 : X ⟶ 0) (0 : Y ⟶ 0) ≅ X ⨯ Y :=
limit.iso_limit_cone ⟨_, is_pullback_of_is_terminal_is_product _ _ _ _
has_zero_object.zero_is_terminal (prod_is_prod X Y)⟩
@[simp] lemma pullback_zero_zero_iso_inv_fst (X Y : C) [has_binary_product X Y] :
(pullback_zero_zero_iso X Y).inv ≫ pullback.fst = prod.fst :=
by { dsimp [pullback_zero_zero_iso], simp, }
@[simp] lemma pullback_zero_zero_iso_inv_snd (X Y : C) [has_binary_product X Y] :
(pullback_zero_zero_iso X Y).inv ≫ pullback.snd = prod.snd :=
by { dsimp [pullback_zero_zero_iso], simp, }
@[simp] lemma pullback_zero_zero_iso_hom_fst (X Y : C) [has_binary_product X Y] :
(pullback_zero_zero_iso X Y).hom ≫ prod.fst = pullback.fst :=
by { simp [←iso.eq_inv_comp], }
@[simp] lemma pullback_zero_zero_iso_hom_snd (X Y : C) [has_binary_product X Y] :
(pullback_zero_zero_iso X Y).hom ≫ prod.snd = pullback.snd :=
by { simp [←iso.eq_inv_comp], }
instance has_pushout_over_zero
(X Y : C) [has_binary_coproduct X Y] : has_pushout (0 : 0 ⟶ X) (0 : 0 ⟶ Y) :=
has_colimit.mk ⟨_, is_pushout_of_is_initial_is_coproduct _ _ _ _
has_zero_object.zero_is_initial (coprod_is_coprod X Y)⟩
/-- The pushout over the zero object is the coproduct. -/
def pushout_zero_zero_iso
(X Y : C) [has_binary_coproduct X Y] : pushout (0 : 0 ⟶ X) (0 : 0 ⟶ Y) ≅ X ⨿ Y :=
colimit.iso_colimit_cocone ⟨_, is_pushout_of_is_initial_is_coproduct _ _ _ _
has_zero_object.zero_is_initial (coprod_is_coprod X Y)⟩
@[simp] lemma inl_pushout_zero_zero_iso_hom (X Y : C) [has_binary_coproduct X Y] :
pushout.inl ≫ (pushout_zero_zero_iso X Y).hom = coprod.inl :=
by { dsimp [pushout_zero_zero_iso], simp, }
@[simp] lemma inr_pushout_zero_zero_iso_hom (X Y : C) [has_binary_coproduct X Y] :
pushout.inr ≫ (pushout_zero_zero_iso X Y).hom = coprod.inr :=
by { dsimp [pushout_zero_zero_iso], simp, }
@[simp] lemma inl_pushout_zero_zero_iso_inv (X Y : C) [has_binary_coproduct X Y] :
coprod.inl ≫ (pushout_zero_zero_iso X Y).inv = pushout.inl :=
by { simp [iso.comp_inv_eq], }
@[simp] lemma inr_pushout_zero_zero_iso_inv (X Y : C) [has_binary_coproduct X Y] :
coprod.inr ≫ (pushout_zero_zero_iso X Y).inv = pushout.inr :=
by { simp [iso.comp_inv_eq], }
end category_theory.limits
|
68c79e5c3fcf4e877dc433f99987f15627fa7d3a | 94e33a31faa76775069b071adea97e86e218a8ee | /src/analysis/convex/gauge.lean | 3236b6575c0f5725e1d37731617487f07871a50c | [
"Apache-2.0"
] | permissive | urkud/mathlib | eab80095e1b9f1513bfb7f25b4fa82fa4fd02989 | 6379d39e6b5b279df9715f8011369a301b634e41 | refs/heads/master | 1,658,425,342,662 | 1,658,078,703,000 | 1,658,078,703,000 | 186,910,338 | 0 | 0 | Apache-2.0 | 1,568,512,083,000 | 1,557,958,709,000 | Lean | UTF-8 | Lean | false | false | 18,038 | lean | /-
Copyright (c) 2021 Yaël Dillies, Bhavik Mehta. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies, Bhavik Mehta
-/
import analysis.convex.star
import analysis.normed_space.pointwise
import analysis.seminorm
import tactic.congrm
/-!
# The Minkowksi functional
This file defines the Minkowski functional, aka gauge.
The Minkowski functional of a set `s` is the function which associates each point to how much you
need to scale `s` for `x` to be inside it. When `s` is symmetric, convex and absorbent, its gauge is
a seminorm. Reciprocally, any seminorm arises as the gauge of some set, namely its unit ball. This
induces the equivalence of seminorms and locally convex topological vector spaces.
## Main declarations
For a real vector space,
* `gauge`: Aka Minkowksi functional. `gauge s x` is the least (actually, an infimum) `r` such
that `x ∈ r • s`.
* `gauge_seminorm`: The Minkowski functional as a seminorm, when `s` is symmetric, convex and
absorbent.
## References
* [H. H. Schaefer, *Topological Vector Spaces*][schaefer1966]
## Tags
Minkowski functional, gauge
-/
open normed_field set
open_locale pointwise
noncomputable theory
variables {E : Type*}
section add_comm_group
variables [add_comm_group E] [module ℝ E]
/--The Minkowski functional. Given a set `s` in a real vector space, `gauge s` is the functional
which sends `x : E` to the smallest `r : ℝ` such that `x` is in `s` scaled by `r`. -/
def gauge (s : set E) (x : E) : ℝ := Inf {r : ℝ | 0 < r ∧ x ∈ r • s}
variables {s t : set E} {a : ℝ} {x : E}
lemma gauge_def : gauge s x = Inf {r ∈ set.Ioi 0 | x ∈ r • s} := rfl
/-- An alternative definition of the gauge using scalar multiplication on the element rather than on
the set. -/
lemma gauge_def' : gauge s x = Inf {r ∈ set.Ioi 0 | r⁻¹ • x ∈ s} :=
begin
congrm Inf (λ r, _),
exact and_congr_right (λ hr, mem_smul_set_iff_inv_smul_mem₀ hr.ne' _ _),
end
private lemma gauge_set_bdd_below : bdd_below {r : ℝ | 0 < r ∧ x ∈ r • s} := ⟨0, λ r hr, hr.1.le⟩
/-- If the given subset is `absorbent` then the set we take an infimum over in `gauge` is nonempty,
which is useful for proving many properties about the gauge. -/
lemma absorbent.gauge_set_nonempty (absorbs : absorbent ℝ s) :
{r : ℝ | 0 < r ∧ x ∈ r • s}.nonempty :=
let ⟨r, hr₁, hr₂⟩ := absorbs x in ⟨r, hr₁, hr₂ r (real.norm_of_nonneg hr₁.le).ge⟩
lemma gauge_mono (hs : absorbent ℝ s) (h : s ⊆ t) : gauge t ≤ gauge s :=
λ x, cInf_le_cInf gauge_set_bdd_below hs.gauge_set_nonempty $ λ r hr, ⟨hr.1, smul_set_mono h hr.2⟩
lemma exists_lt_of_gauge_lt (absorbs : absorbent ℝ s) (h : gauge s x < a) :
∃ b, 0 < b ∧ b < a ∧ x ∈ b • s :=
begin
obtain ⟨b, ⟨hb, hx⟩, hba⟩ := exists_lt_of_cInf_lt absorbs.gauge_set_nonempty h,
exact ⟨b, hb, hba, hx⟩,
end
/-- The gauge evaluated at `0` is always zero (mathematically this requires `0` to be in the set `s`
but, the real infimum of the empty set in Lean being defined as `0`, it holds unconditionally). -/
@[simp] lemma gauge_zero : gauge s 0 = 0 :=
begin
rw gauge_def',
by_cases (0 : E) ∈ s,
{ simp only [smul_zero, sep_true, h, cInf_Ioi] },
{ simp only [smul_zero, sep_false, h, real.Inf_empty] }
end
@[simp] lemma gauge_zero' : gauge (0 : set E) = 0 :=
begin
ext,
rw gauge_def',
obtain rfl | hx := eq_or_ne x 0,
{ simp only [cInf_Ioi, mem_zero, pi.zero_apply, eq_self_iff_true, sep_true, smul_zero] },
{ simp only [mem_zero, pi.zero_apply, inv_eq_zero, smul_eq_zero],
convert real.Inf_empty,
exact eq_empty_iff_forall_not_mem.2 (λ r hr, hr.2.elim (ne_of_gt hr.1) hx) }
end
@[simp] lemma gauge_empty : gauge (∅ : set E) = 0 :=
by { ext, simp only [gauge_def', real.Inf_empty, mem_empty_eq, pi.zero_apply, sep_false] }
lemma gauge_of_subset_zero (h : s ⊆ 0) : gauge s = 0 :=
by { obtain rfl | rfl := subset_singleton_iff_eq.1 h, exacts [gauge_empty, gauge_zero'] }
/-- The gauge is always nonnegative. -/
lemma gauge_nonneg (x : E) : 0 ≤ gauge s x := real.Inf_nonneg _ $ λ x hx, hx.1.le
lemma gauge_neg (symmetric : ∀ x ∈ s, -x ∈ s) (x : E) : gauge s (-x) = gauge s x :=
begin
have : ∀ x, -x ∈ s ↔ x ∈ s := λ x, ⟨λ h, by simpa using symmetric _ h, symmetric x⟩,
rw [gauge_def', gauge_def'],
simp_rw [smul_neg, this],
end
lemma gauge_le_of_mem (ha : 0 ≤ a) (hx : x ∈ a • s) : gauge s x ≤ a :=
begin
obtain rfl | ha' := ha.eq_or_lt,
{ rw [mem_singleton_iff.1 (zero_smul_set_subset _ hx), gauge_zero] },
{ exact cInf_le gauge_set_bdd_below ⟨ha', hx⟩ }
end
lemma gauge_le_eq (hs₁ : convex ℝ s) (hs₀ : (0 : E) ∈ s) (hs₂ : absorbent ℝ s) (ha : 0 ≤ a) :
{x | gauge s x ≤ a} = ⋂ (r : ℝ) (H : a < r), r • s :=
begin
ext,
simp_rw [set.mem_Inter, set.mem_set_of_eq],
refine ⟨λ h r hr, _, λ h, le_of_forall_pos_lt_add (λ ε hε, _)⟩,
{ have hr' := ha.trans_lt hr,
rw mem_smul_set_iff_inv_smul_mem₀ hr'.ne',
obtain ⟨δ, δ_pos, hδr, hδ⟩ := exists_lt_of_gauge_lt hs₂ (h.trans_lt hr),
suffices : (r⁻¹ * δ) • δ⁻¹ • x ∈ s,
{ rwa [smul_smul, mul_inv_cancel_right₀ δ_pos.ne'] at this },
rw mem_smul_set_iff_inv_smul_mem₀ δ_pos.ne' at hδ,
refine hs₁.smul_mem_of_zero_mem hs₀ hδ
⟨mul_nonneg (inv_nonneg.2 hr'.le) δ_pos.le, _⟩,
rw [inv_mul_le_iff hr', mul_one],
exact hδr.le },
{ have hε' := (lt_add_iff_pos_right a).2 (half_pos hε),
exact (gauge_le_of_mem (ha.trans hε'.le) $ h _ hε').trans_lt
(add_lt_add_left (half_lt_self hε) _) }
end
lemma gauge_lt_eq' (absorbs : absorbent ℝ s) (a : ℝ) :
{x | gauge s x < a} = ⋃ (r : ℝ) (H : 0 < r) (H : r < a), r • s :=
begin
ext,
simp_rw [mem_set_of_eq, mem_Union, exists_prop],
exact ⟨exists_lt_of_gauge_lt absorbs,
λ ⟨r, hr₀, hr₁, hx⟩, (gauge_le_of_mem hr₀.le hx).trans_lt hr₁⟩,
end
lemma gauge_lt_eq (absorbs : absorbent ℝ s) (a : ℝ) :
{x | gauge s x < a} = ⋃ (r ∈ set.Ioo 0 (a : ℝ)), r • s :=
begin
ext,
simp_rw [mem_set_of_eq, mem_Union, exists_prop, mem_Ioo, and_assoc],
exact ⟨exists_lt_of_gauge_lt absorbs,
λ ⟨r, hr₀, hr₁, hx⟩, (gauge_le_of_mem hr₀.le hx).trans_lt hr₁⟩,
end
lemma gauge_lt_one_subset_self (hs : convex ℝ s) (h₀ : (0 : E) ∈ s) (absorbs : absorbent ℝ s) :
{x | gauge s x < 1} ⊆ s :=
begin
rw gauge_lt_eq absorbs,
refine set.Union₂_subset (λ r hr _, _),
rintro ⟨y, hy, rfl⟩,
exact hs.smul_mem_of_zero_mem h₀ hy (Ioo_subset_Icc_self hr),
end
lemma gauge_le_one_of_mem {x : E} (hx : x ∈ s) : gauge s x ≤ 1 :=
gauge_le_of_mem zero_le_one $ by rwa one_smul
lemma self_subset_gauge_le_one : s ⊆ {x | gauge s x ≤ 1} := λ x, gauge_le_one_of_mem
lemma convex.gauge_le (hs : convex ℝ s) (h₀ : (0 : E) ∈ s) (absorbs : absorbent ℝ s) (a : ℝ) :
convex ℝ {x | gauge s x ≤ a} :=
begin
by_cases ha : 0 ≤ a,
{ rw gauge_le_eq hs h₀ absorbs ha,
exact convex_Inter (λ i, convex_Inter (λ hi, hs.smul _)) },
{ convert convex_empty,
exact eq_empty_iff_forall_not_mem.2 (λ x hx, ha $ (gauge_nonneg _).trans hx) }
end
lemma balanced.star_convex (hs : balanced ℝ s) : star_convex ℝ 0 s :=
star_convex_zero_iff.2 $ λ x hx a ha₀ ha₁,
hs _ (by rwa real.norm_of_nonneg ha₀) (smul_mem_smul_set hx)
lemma le_gauge_of_not_mem (hs₀ : star_convex ℝ 0 s) (hs₂ : absorbs ℝ s {x}) (hx : x ∉ a • s) :
a ≤ gauge s x :=
begin
rw star_convex_zero_iff at hs₀,
obtain ⟨r, hr, h⟩ := hs₂,
refine le_cInf ⟨r, hr, singleton_subset_iff.1 $ h _ (real.norm_of_nonneg hr.le).ge⟩ _,
rintro b ⟨hb, x, hx', rfl⟩,
refine not_lt.1 (λ hba, hx _),
have ha := hb.trans hba,
refine ⟨(a⁻¹ * b) • x, hs₀ hx' (mul_nonneg (inv_nonneg.2 ha.le) hb.le) _, _⟩,
{ rw ←div_eq_inv_mul,
exact div_le_one_of_le hba.le ha.le },
{ rw [←mul_smul, mul_inv_cancel_left₀ ha.ne'] }
end
lemma one_le_gauge_of_not_mem (hs₁ : star_convex ℝ 0 s) (hs₂ : absorbs ℝ s {x}) (hx : x ∉ s) :
1 ≤ gauge s x :=
le_gauge_of_not_mem hs₁ hs₂ $ by rwa one_smul
section linear_ordered_field
variables {α : Type*} [linear_ordered_field α] [mul_action_with_zero α ℝ] [ordered_smul α ℝ]
lemma gauge_smul_of_nonneg [mul_action_with_zero α E] [is_scalar_tower α ℝ (set E)] {s : set E}
{a : α} (ha : 0 ≤ a) (x : E) :
gauge s (a • x) = a • gauge s x :=
begin
obtain rfl | ha' := ha.eq_or_lt,
{ rw [zero_smul, gauge_zero, zero_smul] },
rw [gauge_def', gauge_def', ←real.Inf_smul_of_nonneg ha],
congr' 1,
ext r,
simp_rw [set.mem_smul_set, set.mem_sep_eq],
split,
{ rintro ⟨hr, hx⟩,
simp_rw mem_Ioi at ⊢ hr,
rw ←mem_smul_set_iff_inv_smul_mem₀ hr.ne' at hx,
have := smul_pos (inv_pos.2 ha') hr,
refine ⟨a⁻¹ • r, ⟨this, _⟩, smul_inv_smul₀ ha'.ne' _⟩,
rwa [←mem_smul_set_iff_inv_smul_mem₀ this.ne', smul_assoc,
mem_smul_set_iff_inv_smul_mem₀ (inv_ne_zero ha'.ne'), inv_inv] },
{ rintro ⟨r, ⟨hr, hx⟩, rfl⟩,
rw mem_Ioi at ⊢ hr,
rw ←mem_smul_set_iff_inv_smul_mem₀ hr.ne' at hx,
have := smul_pos ha' hr,
refine ⟨this, _⟩,
rw [←mem_smul_set_iff_inv_smul_mem₀ this.ne', smul_assoc],
exact smul_mem_smul_set hx }
end
/-- In textbooks, this is the homogeneity of the Minkowksi functional. -/
lemma gauge_smul [module α E] [is_scalar_tower α ℝ (set E)] {s : set E}
(symmetric : ∀ x ∈ s, -x ∈ s) (r : α) (x : E) :
gauge s (r • x) = abs r • gauge s x :=
begin
rw ←gauge_smul_of_nonneg (abs_nonneg r),
obtain h | h := abs_choice r,
{ rw h },
{ rw [h, neg_smul, gauge_neg symmetric] },
{ apply_instance }
end
lemma gauge_smul_left_of_nonneg [mul_action_with_zero α E] [smul_comm_class α ℝ ℝ]
[is_scalar_tower α ℝ ℝ] [is_scalar_tower α ℝ E] {s : set E} {a : α} (ha : 0 ≤ a) :
gauge (a • s) = a⁻¹ • gauge s :=
begin
obtain rfl | ha' := ha.eq_or_lt,
{ rw [inv_zero, zero_smul, gauge_of_subset_zero (zero_smul_set_subset _)] },
ext,
rw [gauge_def', pi.smul_apply, gauge_def', ←real.Inf_smul_of_nonneg (inv_nonneg.2 ha)],
congr' 1,
ext r,
simp_rw [set.mem_smul_set, set.mem_sep_eq],
split,
{ rintro ⟨hr, y, hy, h⟩,
simp_rw [mem_Ioi] at ⊢ hr,
refine ⟨a • r, ⟨smul_pos ha' hr, _⟩, inv_smul_smul₀ ha'.ne' _⟩,
rwa [smul_inv₀, smul_assoc, ←h, inv_smul_smul₀ ha'.ne'] },
{ rintro ⟨r, ⟨hr, hx⟩, rfl⟩,
rw mem_Ioi at ⊢ hr,
have := smul_pos ha' hr,
refine ⟨smul_pos (inv_pos.2 ha') hr, r⁻¹ • x, hx, _⟩,
rw [smul_inv₀, smul_assoc, inv_inv] }
end
lemma gauge_smul_left [module α E] [smul_comm_class α ℝ ℝ] [is_scalar_tower α ℝ ℝ]
[is_scalar_tower α ℝ E] {s : set E} (symmetric : ∀ x ∈ s, -x ∈ s) (a : α) :
gauge (a • s) = |a|⁻¹ • gauge s :=
begin
rw ←gauge_smul_left_of_nonneg (abs_nonneg a),
obtain h | h := abs_choice a,
{ rw h },
{ rw [h, set.neg_smul_set, ←set.smul_set_neg],
congr,
ext y,
refine ⟨symmetric _, λ hy, _⟩,
rw ←neg_neg y,
exact symmetric _ hy },
{ apply_instance }
end
end linear_ordered_field
section topological_space
variables [topological_space E] [has_continuous_smul ℝ E]
lemma interior_subset_gauge_lt_one (s : set E) : interior s ⊆ {x | gauge s x < 1} :=
begin
intros x hx,
let f : ℝ → E := λ t, t • x,
have hf : continuous f,
{ continuity },
let s' := f ⁻¹' (interior s),
have hs' : is_open s' := hf.is_open_preimage _ is_open_interior,
have one_mem : (1 : ℝ) ∈ s',
{ simpa only [s', f, set.mem_preimage, one_smul] },
obtain ⟨ε, hε₀, hε⟩ := (metric.nhds_basis_closed_ball.1 _).1
(is_open_iff_mem_nhds.1 hs' 1 one_mem),
rw real.closed_ball_eq_Icc at hε,
have hε₁ : 0 < 1 + ε := hε₀.trans (lt_one_add ε),
have : (1 + ε)⁻¹ < 1,
{ rw inv_lt_one_iff,
right,
linarith },
refine (gauge_le_of_mem (inv_nonneg.2 hε₁.le) _).trans_lt this,
rw mem_inv_smul_set_iff₀ hε₁.ne',
exact interior_subset
(hε ⟨(sub_le_self _ hε₀.le).trans ((le_add_iff_nonneg_right _).2 hε₀.le), le_rfl⟩),
end
lemma gauge_lt_one_eq_self_of_open (hs₁ : convex ℝ s) (hs₀ : (0 : E) ∈ s) (hs₂ : is_open s) :
{x | gauge s x < 1} = s :=
begin
refine (gauge_lt_one_subset_self hs₁ ‹_› $ absorbent_nhds_zero $ hs₂.mem_nhds hs₀).antisymm _,
convert interior_subset_gauge_lt_one s,
exact hs₂.interior_eq.symm,
end
lemma gauge_lt_one_of_mem_of_open (hs₁ : convex ℝ s) (hs₀ : (0 : E) ∈ s) (hs₂ : is_open s)
{x : E} (hx : x ∈ s) :
gauge s x < 1 :=
by rwa ←gauge_lt_one_eq_self_of_open hs₁ hs₀ hs₂ at hx
lemma gauge_lt_of_mem_smul (x : E) (ε : ℝ) (hε : 0 < ε) (hs₀ : (0 : E) ∈ s)
(hs₁ : convex ℝ s) (hs₂ : is_open s) (hx : x ∈ ε • s) :
gauge s x < ε :=
begin
have : ε⁻¹ • x ∈ s,
{ rwa ←mem_smul_set_iff_inv_smul_mem₀ hε.ne' },
have h_gauge_lt := gauge_lt_one_of_mem_of_open hs₁ hs₀ hs₂ this,
rwa [gauge_smul_of_nonneg (inv_nonneg.2 hε.le), smul_eq_mul, inv_mul_lt_iff hε, mul_one]
at h_gauge_lt,
apply_instance
end
end topological_space
lemma gauge_add_le (hs : convex ℝ s) (absorbs : absorbent ℝ s) (x y : E) :
gauge s (x + y) ≤ gauge s x + gauge s y :=
begin
refine le_of_forall_pos_lt_add (λ ε hε, _),
obtain ⟨a, ha, ha', hx⟩ := exists_lt_of_gauge_lt absorbs
(lt_add_of_pos_right (gauge s x) (half_pos hε)),
obtain ⟨b, hb, hb', hy⟩ := exists_lt_of_gauge_lt absorbs
(lt_add_of_pos_right (gauge s y) (half_pos hε)),
rw mem_smul_set_iff_inv_smul_mem₀ ha.ne' at hx,
rw mem_smul_set_iff_inv_smul_mem₀ hb.ne' at hy,
suffices : gauge s (x + y) ≤ a + b,
{ linarith },
have hab : 0 < a + b := add_pos ha hb,
apply gauge_le_of_mem hab.le,
have := convex_iff_div.1 hs hx hy ha.le hb.le hab,
rwa [smul_smul, smul_smul, ←mul_div_right_comm, ←mul_div_right_comm, mul_inv_cancel ha.ne',
mul_inv_cancel hb.ne', ←smul_add, one_div, ←mem_smul_set_iff_inv_smul_mem₀ hab.ne'] at this,
end
/-- `gauge s` as a seminorm when `s` is symmetric, convex and absorbent. -/
@[simps] def gauge_seminorm (hs₀ : ∀ x ∈ s, -x ∈ s) (hs₁ : convex ℝ s) (hs₂ : absorbent ℝ s) :
seminorm ℝ E :=
seminorm.of (gauge s) (gauge_add_le hs₁ hs₂)
(λ r x, by rw [gauge_smul hs₀, real.norm_eq_abs, smul_eq_mul]; apply_instance)
section gauge_seminorm
variables {hs₀ : ∀ x ∈ s, -x ∈ s} {hs₁ : convex ℝ s} {hs₂ : absorbent ℝ s}
section topological_space
variables [topological_space E] [has_continuous_smul ℝ E]
lemma gauge_seminorm_lt_one_of_open (hs : is_open s) {x : E} (hx : x ∈ s) :
gauge_seminorm hs₀ hs₁ hs₂ x < 1 :=
gauge_lt_one_of_mem_of_open hs₁ hs₂.zero_mem hs hx
end topological_space
end gauge_seminorm
/-- Any seminorm arises as the gauge of its unit ball. -/
@[simp] protected lemma seminorm.gauge_ball (p : seminorm ℝ E) : gauge (p.ball 0 1) = p :=
begin
ext,
obtain hp | hp := {r : ℝ | 0 < r ∧ x ∈ r • p.ball 0 1}.eq_empty_or_nonempty,
{ rw [gauge, hp, real.Inf_empty],
by_contra,
have hpx : 0 < p x := (p.nonneg x).lt_of_ne h,
have hpx₂ : 0 < 2 * p x := mul_pos zero_lt_two hpx,
refine hp.subset ⟨hpx₂, (2 * p x)⁻¹ • x, _, smul_inv_smul₀ hpx₂.ne' _⟩,
rw [p.mem_ball_zero, p.smul, real.norm_eq_abs, abs_of_pos (inv_pos.2 hpx₂), inv_mul_lt_iff hpx₂,
mul_one],
exact lt_mul_of_one_lt_left hpx one_lt_two },
refine is_glb.cInf_eq ⟨λ r, _, λ r hr, le_of_forall_pos_le_add $ λ ε hε, _⟩ hp,
{ rintro ⟨hr, y, hy, rfl⟩,
rw p.mem_ball_zero at hy,
rw [p.smul, real.norm_eq_abs, abs_of_pos hr],
exact mul_le_of_le_one_right hr.le hy.le },
{ have hpε : 0 < p x + ε := add_pos_of_nonneg_of_pos (p.nonneg _) hε,
refine hr ⟨hpε, (p x + ε)⁻¹ • x, _, smul_inv_smul₀ hpε.ne' _⟩,
rw [p.mem_ball_zero, p.smul, real.norm_eq_abs, abs_of_pos (inv_pos.2 hpε), inv_mul_lt_iff hpε,
mul_one],
exact lt_add_of_pos_right _ hε }
end
lemma seminorm.gauge_seminorm_ball (p : seminorm ℝ E) :
gauge_seminorm (λ x, p.symmetric_ball_zero 1) (p.convex_ball 0 1)
(p.absorbent_ball_zero zero_lt_one) = p := fun_like.coe_injective p.gauge_ball
end add_comm_group
section norm
variables [semi_normed_group E] [normed_space ℝ E] {s : set E} {r : ℝ} {x : E}
lemma gauge_unit_ball (x : E) : gauge (metric.ball (0 : E) 1) x = ∥x∥ :=
begin
obtain rfl | hx := eq_or_ne x 0,
{ rw [norm_zero, gauge_zero] },
refine (le_of_forall_pos_le_add $ λ ε hε, _).antisymm _,
{ have := add_pos_of_nonneg_of_pos (norm_nonneg x) hε,
refine gauge_le_of_mem this.le _,
rw [smul_ball this.ne', smul_zero, real.norm_of_nonneg this.le, mul_one, mem_ball_zero_iff],
exact lt_add_of_pos_right _ hε },
refine le_gauge_of_not_mem balanced_ball_zero.star_convex
(absorbent_ball_zero zero_lt_one).absorbs (λ h, _),
obtain hx' | hx' := eq_or_ne (∥x∥) 0,
{ rw hx' at h,
exact hx (zero_smul_set_subset _ h) },
{ rw [mem_smul_set_iff_inv_smul_mem₀ hx', mem_ball_zero_iff, norm_smul, norm_inv, norm_norm,
inv_mul_cancel hx'] at h,
exact lt_irrefl _ h }
end
lemma gauge_ball (hr : 0 < r) (x : E) : gauge (metric.ball (0 : E) r) x = ∥x∥ / r :=
begin
rw [←smul_unit_ball_of_pos hr, gauge_smul_left, pi.smul_apply, gauge_unit_ball, smul_eq_mul,
abs_of_nonneg hr.le, div_eq_inv_mul],
simp_rw [mem_ball_zero_iff, norm_neg],
exact λ _, id,
end
lemma mul_gauge_le_norm (hs : metric.ball (0 : E) r ⊆ s) : r * gauge s x ≤ ∥x∥ :=
begin
obtain hr | hr := le_or_lt r 0,
{ exact (mul_nonpos_of_nonpos_of_nonneg hr $ gauge_nonneg _).trans (norm_nonneg _) },
rw [mul_comm, ←le_div_iff hr, ←gauge_ball hr],
exact gauge_mono (absorbent_ball_zero hr) hs x,
end
end norm
|
d1de0edbe5ed1ab2cec59345a15993e9cf1d00c7 | 4d2583807a5ac6caaffd3d7a5f646d61ca85d532 | /src/topology/algebra/affine.lean | 49a4a2437183435ea8d3e755ad9ab74dab55f77d | [
"Apache-2.0"
] | permissive | AntoineChambert-Loir/mathlib | 64aabb896129885f12296a799818061bc90da1ff | 07be904260ab6e36a5769680b6012f03a4727134 | refs/heads/master | 1,693,187,631,771 | 1,636,719,886,000 | 1,636,719,886,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 2,309 | lean | /-
Copyright (c) 2020 Frédéric Dupuis. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Frédéric Dupuis
-/
import topology.continuous_function.algebra
import linear_algebra.affine_space.affine_map
/-!
# Topological properties of affine spaces and maps
For now, this contains only a few facts regarding the continuity of affine maps in the special
case when the point space and vector space are the same.
TODO: Deal with the case where the point spaces are different from the vector spaces. Note that
we do have some results in this direction under the assumption that the topologies are induced by
(semi)norms.
-/
namespace affine_map
variables {R E F : Type*}
variables [add_comm_group E] [topological_space E]
variables [add_comm_group F] [topological_space F] [topological_add_group F]
section ring
variables [ring R] [module R E] [module R F]
/-- An affine map is continuous iff its underlying linear map is continuous. See also
`affine_map.continuous_linear_iff`. -/
lemma continuous_iff {f : E →ᵃ[R] F} :
continuous f ↔ continuous f.linear :=
begin
split,
{ intro hc,
rw decomp' f,
have := hc.sub continuous_const,
exact this, },
{ intro hc,
rw decomp f,
have := hc.add continuous_const,
exact this }
end
/-- The line map is continuous. -/
@[continuity]
lemma line_map_continuous [topological_space R] [has_continuous_smul R F] {p v : F} :
continuous ⇑(line_map p v : R →ᵃ[R] F) :=
continuous_iff.mpr $ (continuous_id.smul continuous_const).add $
@continuous_const _ _ _ _ (0 : F)
end ring
section comm_ring
variables [comm_ring R] [module R F] [topological_space R] [has_continuous_smul R F]
@[continuity]
lemma homothety_continuous (x : F) (t : R) : continuous $ homothety x t :=
begin
suffices : ⇑(homothety x t) = λ y, t • (y - x) + x, { rw this, continuity, },
ext y,
simp [homothety_apply],
end
end comm_ring
section field
variables [field R] [module R F] [topological_space R] [has_continuous_smul R F]
lemma homothety_is_open_map (x : F) (t : R) (ht : t ≠ 0) : is_open_map $ homothety x t :=
begin
apply is_open_map.of_inverse (homothety_continuous x t⁻¹);
intros e;
simp [← affine_map.comp_apply, ← homothety_mul, ht],
end
end field
end affine_map
|
43405336bc49a7f663d0ef8faea06a0c35c68add | 947b78d97130d56365ae2ec264df196ce769371a | /tests/lean/run/kernel2.lean | f493d79c8747ecc073ee5f52081c361dc10b98fb | [
"Apache-2.0"
] | permissive | shyamalschandra/lean4 | 27044812be8698f0c79147615b1d5090b9f4b037 | 6e7a883b21eaf62831e8111b251dc9b18f40e604 | refs/heads/master | 1,671,417,126,371 | 1,601,859,995,000 | 1,601,860,020,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 1,172 | lean | import Lean
new_frontend
open Lean
def checkDefEq (a b : Name) : CoreM Unit := do
let env ← getEnv;
let a := mkConst a;
let b := mkConst b;
let r := Kernel.isDefEq env {} a b;
IO.println (toString a ++ " =?= " ++ toString b ++ " := " ++ toString r)
def whnf (a : Name) : CoreM Unit := do
let env ← getEnv;
let a := mkConst a;
let r := Kernel.whnf env {} a;
IO.println (toString a ++ " ==> " ++ toString r)
partial def fact : Nat → Nat
| 0 => 1
| (n+1) => (n+1)*fact n
def c1 := 30000000000 + 10000000000
def c2 := 40000000000
def c3 := fact 10
def v1 := 3628800
def v2 := 3628801
#eval whnf `c3
#eval checkDefEq `c3 `v1
#eval checkDefEq `c3 `v2
#eval checkDefEq `c1 `c2
def c4 := decide (100000000 < 20000000000)
#eval whnf `c4
#eval checkDefEq `c4 `Bool.true
def c5 := "h".length
def c6 := 1
set_option pp.all true
#eval whnf `c5
#eval checkDefEq `c5 `c6
def c7 := decide ("hello" = "world")
#eval whnf `c7
def c8 := "hello".length
#eval whnf `c8
def c9 : String := "hello" ++ "world"
def c10 : String := "helloworld"
#eval checkDefEq `c9 `c10
def c11 : Bool := decide ('a' = 'b')
#eval whnf `c11
def c12 : Nat := 'a'.toNat
#eval whnf `c12
|
183fc0105318bb924a93afae37101ef17c58186d | 4727251e0cd73359b15b664c3170e5d754078599 | /src/algebra/ring/opposite.lean | a833861e4dd1525b31286667507b0a9a4a3d129e | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 9,286 | lean | /-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau
-/
import algebra.ring.basic
import algebra.group.opposite
/-!
# Ring structures on the multiplicative opposite
-/
universes u v
variables (α : Type u)
namespace mul_opposite
instance [distrib α] : distrib αᵐᵒᵖ :=
{ left_distrib := λ x y z, unop_injective $ add_mul (unop y) (unop z) (unop x),
right_distrib := λ x y z, unop_injective $ mul_add (unop z) (unop x) (unop y),
.. mul_opposite.has_add α, .. mul_opposite.has_mul α }
instance [mul_zero_class α] : mul_zero_class αᵐᵒᵖ :=
{ zero := 0,
mul := (*),
zero_mul := λ x, unop_injective $ mul_zero $ unop x,
mul_zero := λ x, unop_injective $ zero_mul $ unop x }
instance [mul_zero_one_class α] : mul_zero_one_class αᵐᵒᵖ :=
{ .. mul_opposite.mul_zero_class α, .. mul_opposite.mul_one_class α }
instance [semigroup_with_zero α] : semigroup_with_zero αᵐᵒᵖ :=
{ .. mul_opposite.semigroup α, .. mul_opposite.mul_zero_class α }
instance [monoid_with_zero α] : monoid_with_zero αᵐᵒᵖ :=
{ .. mul_opposite.monoid α, .. mul_opposite.mul_zero_one_class α }
instance [non_unital_non_assoc_semiring α] : non_unital_non_assoc_semiring αᵐᵒᵖ :=
{ .. mul_opposite.add_comm_monoid α, .. mul_opposite.mul_zero_class α, .. mul_opposite.distrib α }
instance [non_unital_semiring α] : non_unital_semiring αᵐᵒᵖ :=
{ .. mul_opposite.semigroup_with_zero α, .. mul_opposite.non_unital_non_assoc_semiring α }
instance [non_assoc_semiring α] : non_assoc_semiring αᵐᵒᵖ :=
{ .. mul_opposite.mul_zero_one_class α, .. mul_opposite.non_unital_non_assoc_semiring α }
instance [semiring α] : semiring αᵐᵒᵖ :=
{ .. mul_opposite.non_unital_semiring α, .. mul_opposite.non_assoc_semiring α,
.. mul_opposite.monoid_with_zero α }
instance [non_unital_comm_semiring α] : non_unital_comm_semiring αᵐᵒᵖ :=
{ .. mul_opposite.non_unital_semiring α, .. mul_opposite.comm_semigroup α }
instance [comm_semiring α] : comm_semiring αᵐᵒᵖ :=
{ .. mul_opposite.semiring α, .. mul_opposite.comm_semigroup α }
instance [non_unital_non_assoc_ring α] : non_unital_non_assoc_ring αᵐᵒᵖ :=
{ .. mul_opposite.add_comm_group α, .. mul_opposite.mul_zero_class α, .. mul_opposite.distrib α}
instance [non_unital_ring α] : non_unital_ring αᵐᵒᵖ :=
{ .. mul_opposite.add_comm_group α, .. mul_opposite.semigroup_with_zero α,
.. mul_opposite.distrib α}
instance [non_assoc_ring α] : non_assoc_ring αᵐᵒᵖ :=
{ .. mul_opposite.add_comm_group α, .. mul_opposite.mul_zero_one_class α, .. mul_opposite.distrib α}
instance [ring α] : ring αᵐᵒᵖ :=
{ .. mul_opposite.add_comm_group α, .. mul_opposite.monoid α, .. mul_opposite.semiring α }
instance [non_unital_comm_ring α] : non_unital_comm_ring αᵐᵒᵖ :=
{ .. mul_opposite.non_unital_ring α, .. mul_opposite.non_unital_comm_semiring α }
instance [comm_ring α] : comm_ring αᵐᵒᵖ :=
{ .. mul_opposite.ring α, .. mul_opposite.comm_semiring α }
instance [has_zero α] [has_mul α] [no_zero_divisors α] : no_zero_divisors αᵐᵒᵖ :=
{ eq_zero_or_eq_zero_of_mul_eq_zero := λ x y (H : op (_ * _) = op (0:α)),
or.cases_on (eq_zero_or_eq_zero_of_mul_eq_zero $ op_injective H)
(λ hy, or.inr $ unop_injective $ hy) (λ hx, or.inl $ unop_injective $ hx), }
instance [ring α] [is_domain α] : is_domain αᵐᵒᵖ :=
{ .. mul_opposite.no_zero_divisors α, .. mul_opposite.ring α, .. mul_opposite.nontrivial α }
instance [group_with_zero α] : group_with_zero αᵐᵒᵖ :=
{ mul_inv_cancel := λ x hx, unop_injective $ inv_mul_cancel $ unop_injective.ne hx,
inv_zero := unop_injective inv_zero,
.. mul_opposite.monoid_with_zero α, .. mul_opposite.div_inv_monoid α,
.. mul_opposite.nontrivial α }
end mul_opposite
namespace add_opposite
instance [distrib α] : distrib αᵃᵒᵖ :=
{ left_distrib := λ x y z, unop_injective $ mul_add x _ _,
right_distrib := λ x y z, unop_injective $ add_mul _ _ z,
.. add_opposite.has_add α, .. @add_opposite.has_mul α _}
instance [mul_zero_class α] : mul_zero_class αᵃᵒᵖ :=
{ zero := 0,
mul := (*),
zero_mul := λ x, unop_injective $ zero_mul $ unop x,
mul_zero := λ x, unop_injective $ mul_zero $ unop x }
instance [mul_zero_one_class α] : mul_zero_one_class αᵃᵒᵖ :=
{ .. add_opposite.mul_zero_class α, .. add_opposite.mul_one_class α }
instance [semigroup_with_zero α] : semigroup_with_zero αᵃᵒᵖ :=
{ .. add_opposite.semigroup α, .. add_opposite.mul_zero_class α }
instance [monoid_with_zero α] : monoid_with_zero αᵃᵒᵖ :=
{ .. add_opposite.monoid α, .. add_opposite.mul_zero_one_class α }
instance [non_unital_non_assoc_semiring α] : non_unital_non_assoc_semiring αᵃᵒᵖ :=
{ .. add_opposite.add_comm_monoid α, .. add_opposite.mul_zero_class α, .. add_opposite.distrib α }
instance [non_unital_semiring α] : non_unital_semiring αᵃᵒᵖ :=
{ .. add_opposite.semigroup_with_zero α, .. add_opposite.non_unital_non_assoc_semiring α }
instance [non_assoc_semiring α] : non_assoc_semiring αᵃᵒᵖ :=
{ .. add_opposite.mul_zero_one_class α, .. add_opposite.non_unital_non_assoc_semiring α }
instance [semiring α] : semiring αᵃᵒᵖ :=
{ .. add_opposite.non_unital_semiring α, .. add_opposite.non_assoc_semiring α,
.. add_opposite.monoid_with_zero α }
instance [non_unital_comm_semiring α] : non_unital_comm_semiring αᵃᵒᵖ :=
{ .. add_opposite.non_unital_semiring α, .. add_opposite.comm_semigroup α }
instance [comm_semiring α] : comm_semiring αᵃᵒᵖ :=
{ .. add_opposite.semiring α, .. add_opposite.comm_semigroup α }
instance [non_unital_non_assoc_ring α] : non_unital_non_assoc_ring αᵃᵒᵖ :=
{ .. add_opposite.add_comm_group α, .. add_opposite.mul_zero_class α, .. add_opposite.distrib α}
instance [non_unital_ring α] : non_unital_ring αᵃᵒᵖ :=
{ .. add_opposite.add_comm_group α, .. add_opposite.semigroup_with_zero α,
.. add_opposite.distrib α}
instance [non_assoc_ring α] : non_assoc_ring αᵃᵒᵖ :=
{ .. add_opposite.add_comm_group α, .. add_opposite.mul_zero_one_class α, .. add_opposite.distrib α}
instance [ring α] : ring αᵃᵒᵖ :=
{ .. add_opposite.add_comm_group α, .. add_opposite.monoid α, .. add_opposite.semiring α }
instance [non_unital_comm_ring α] : non_unital_comm_ring αᵃᵒᵖ :=
{ .. add_opposite.non_unital_ring α, .. add_opposite.non_unital_comm_semiring α }
instance [comm_ring α] : comm_ring αᵃᵒᵖ :=
{ .. add_opposite.ring α, .. add_opposite.comm_semiring α }
instance [has_zero α] [has_mul α] [no_zero_divisors α] : no_zero_divisors αᵃᵒᵖ :=
{ eq_zero_or_eq_zero_of_mul_eq_zero := λ x y (H : op (_ * _) = op (0:α)),
or.imp (λ hx, unop_injective hx) (λ hy, unop_injective hy)
((@eq_zero_or_eq_zero_of_mul_eq_zero α _ _ _ _ _) $ op_injective H) }
instance [ring α] [is_domain α] : is_domain αᵃᵒᵖ :=
{ .. add_opposite.no_zero_divisors α, .. add_opposite.ring α, .. add_opposite.nontrivial α }
instance [group_with_zero α] : group_with_zero αᵃᵒᵖ :=
{ mul_inv_cancel := λ x hx, unop_injective $ mul_inv_cancel $ unop_injective.ne hx,
inv_zero := unop_injective inv_zero,
.. add_opposite.monoid_with_zero α, .. add_opposite.div_inv_monoid α,
.. add_opposite.nontrivial α }
end add_opposite
open mul_opposite
/-- A ring homomorphism `f : R →+* S` such that `f x` commutes with `f y` for all `x, y` defines
a ring homomorphism to `Sᵐᵒᵖ`. -/
@[simps {fully_applied := ff}]
def ring_hom.to_opposite {R S : Type*} [semiring R] [semiring S] (f : R →+* S)
(hf : ∀ x y, commute (f x) (f y)) : R →+* Sᵐᵒᵖ :=
{ to_fun := mul_opposite.op ∘ f,
.. ((op_add_equiv : S ≃+ Sᵐᵒᵖ).to_add_monoid_hom.comp ↑f : R →+ Sᵐᵒᵖ),
.. f.to_monoid_hom.to_opposite hf }
/-- A ring homomorphism `f : R →+* S` such that `f x` commutes with `f y` for all `x, y` defines
a ring homomorphism from `Rᵐᵒᵖ`. -/
@[simps {fully_applied := ff}]
def ring_hom.from_opposite {R S : Type*} [semiring R] [semiring S] (f : R →+* S)
(hf : ∀ x y, commute (f x) (f y)) : Rᵐᵒᵖ →+* S :=
{ to_fun := f ∘ mul_opposite.unop,
.. (f.to_add_monoid_hom.comp (op_add_equiv : R ≃+ Rᵐᵒᵖ).symm.to_add_monoid_hom : Rᵐᵒᵖ →+ S),
.. f.to_monoid_hom.from_opposite hf }
/-- A ring hom `α →+* β` can equivalently be viewed as a ring hom `αᵐᵒᵖ →+* βᵐᵒᵖ`. This is the
action of the (fully faithful) `ᵐᵒᵖ`-functor on morphisms. -/
@[simps]
def ring_hom.op {α β} [non_assoc_semiring α] [non_assoc_semiring β] :
(α →+* β) ≃ (αᵐᵒᵖ →+* βᵐᵒᵖ) :=
{ to_fun := λ f, { ..f.to_add_monoid_hom.mul_op, ..f.to_monoid_hom.op },
inv_fun := λ f, { ..f.to_add_monoid_hom.mul_unop, ..f.to_monoid_hom.unop },
left_inv := λ f, by { ext, refl },
right_inv := λ f, by { ext, simp } }
/-- The 'unopposite' of a ring hom `αᵐᵒᵖ →+* βᵐᵒᵖ`. Inverse to `ring_hom.op`. -/
@[simp] def ring_hom.unop {α β} [non_assoc_semiring α] [non_assoc_semiring β] :
(αᵐᵒᵖ →+* βᵐᵒᵖ) ≃ (α →+* β) := ring_hom.op.symm
|
a62fc4aea7ebe74023d906da8b64fe25aa85bfa5 | 31f556cdeb9239ffc2fad8f905e33987ff4feab9 | /src/Lean/Compiler/LCNF/Simp/Used.lean | d6ce5e43c9640392fc11047bb1c3186da208faae | [
"Apache-2.0",
"LLVM-exception",
"NCSA",
"LGPL-3.0-only",
"LicenseRef-scancode-inner-net-2.0",
"BSD-3-Clause",
"LGPL-2.0-or-later",
"Spencer-94",
"LGPL-2.1-or-later",
"HPND",
"LicenseRef-scancode-pcre",
"ISC",
"LGPL-2.1-only",
"LicenseRef-scancode-other-permissive",
"SunPro",
"CMU-Mach"... | permissive | tobiasgrosser/lean4 | ce0fd9cca0feba1100656679bf41f0bffdbabb71 | ebdbdc10436a4d9d6b66acf78aae7a23f5bd073f | refs/heads/master | 1,673,103,412,948 | 1,664,930,501,000 | 1,664,930,501,000 | 186,870,185 | 0 | 0 | Apache-2.0 | 1,665,129,237,000 | 1,557,939,901,000 | Lean | UTF-8 | Lean | false | false | 2,495 | lean | /-
Copyright (c) 2022 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
import Lean.Compiler.LCNF.Simp.SimpM
namespace Lean.Compiler.LCNF
namespace Simp
/--
Mark `fvarId` as an used free variable.
This is information is used to eliminate dead local declarations.
-/
def markUsedFVar (fvarId : FVarId) : SimpM Unit :=
modify fun s => { s with used := s.used.insert fvarId }
/--
Mark all free variables occurring in `e` as used.
This is information is used to eliminate dead local declarations.
-/
def markUsedExpr (e : Expr) : SimpM Unit :=
modify fun s => { s with used := collectLocalDecls s.used e }
/--
Mark all free variables occurring on the right-hand side of the given let declaration as used.
This is information is used to eliminate dead local declarations.
-/
def markUsedLetDecl (letDecl : LetDecl) : SimpM Unit :=
markUsedExpr letDecl.value
mutual
/--
Mark all free variables occurring in `code` as used.
-/
partial def markUsedCode (code : Code) : SimpM Unit := do
match code with
| .let decl k => markUsedLetDecl decl; markUsedCode k
| .jp decl k | .fun decl k => markUsedFunDecl decl; markUsedCode k
| .return fvarId => markUsedFVar fvarId
| .unreach .. => return ()
| .jmp fvarId args => markUsedFVar fvarId; args.forM markUsedExpr
| .cases c => markUsedFVar c.discr; c.alts.forM fun alt => markUsedCode alt.getCode
/--
Mark all free variables occurring in `funDecl` as used.
-/
partial def markUsedFunDecl (funDecl : FunDecl) : SimpM Unit :=
markUsedCode funDecl.value
end
/--
Return `true` if `fvarId` is in the `used` set.
-/
def isUsed (fvarId : FVarId) : SimpM Bool :=
return (← get).used.contains fvarId
/--
Attach the given `decls` to `code`. For example, assume `decls` is `#[.let _x.1 := 10, .let _x.2 := true]`,
then the result is
```
let _x.1 := 10
let _x.2 := true
<code>
```
-/
def attachCodeDecls (decls : Array CodeDecl) (code : Code) : SimpM Code := do
go decls.size code
where
go (i : Nat) (code : Code) : SimpM Code := do
if i > 0 then
let decl := decls[i-1]!
if (← isUsed decl.fvarId) then
match decl with
| .let decl => markUsedLetDecl decl; go (i-1) (.let decl code)
| .fun decl => markUsedFunDecl decl; go (i-1) (.fun decl code)
| .jp decl => markUsedFunDecl decl; go (i-1) (.jp decl code)
else
eraseCodeDecl decl
go (i-1) code
else
return code
|
44c18e5d336c4138de989b65b2f900f8ac8cadad | 4727251e0cd73359b15b664c3170e5d754078599 | /src/group_theory/commuting_probability.lean | deda527d2a0b107ddb271483a66bd4998bde6ede | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 4,573 | lean | /-
Copyright (c) 2022 Thomas Browning. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Thomas Browning
-/
import group_theory.abelianization
import group_theory.group_action.conj_act
import group_theory.index
/-!
# Commuting Probability
This file introduces the commuting probability of finite groups.
## Main definitions
* `comm_prob`: The commuting probability of a finite type with a multiplication operation.
## Todo
* Neumann's theorem.
-/
noncomputable theory
open_locale classical
open_locale big_operators
open fintype
variables (M : Type*) [fintype M] [has_mul M]
/-- The commuting probability of a finite type with a multiplication operation -/
def comm_prob : ℚ := card {p : M × M // p.1 * p.2 = p.2 * p.1} / card M ^ 2
lemma comm_prob_def : comm_prob M = card {p : M × M // p.1 * p.2 = p.2 * p.1} / card M ^ 2 :=
rfl
lemma comm_prob_pos [h : nonempty M] : 0 < comm_prob M :=
h.elim (λ x, div_pos (nat.cast_pos.mpr (card_pos_iff.mpr ⟨⟨(x, x), rfl⟩⟩))
(pow_pos (nat.cast_pos.mpr card_pos) 2))
lemma comm_prob_le_one : comm_prob M ≤ 1 :=
begin
refine div_le_one_of_le _ (sq_nonneg (card M)),
rw [←nat.cast_pow, nat.cast_le, sq, ←card_prod],
apply set_fintype_card_le_univ,
end
variables {M}
lemma comm_prob_eq_one_iff [h : nonempty M] : comm_prob M = 1 ↔ commutative ((*) : M → M → M) :=
begin
change (card {p : M × M | p.1 * p.2 = p.2 * p.1} : ℚ) / _ = 1 ↔ _,
rw [div_eq_one_iff_eq, ←nat.cast_pow, nat.cast_inj, sq, ←card_prod,
set_fintype_card_eq_univ_iff, set.eq_univ_iff_forall],
{ exact ⟨λ h x y, h (x, y), λ h x, h x.1 x.2⟩ },
{ exact pow_ne_zero 2 (nat.cast_ne_zero.mpr card_ne_zero) },
end
variables (G : Type*) [group G] [fintype G]
lemma card_comm_eq_card_conj_classes_mul_card :
card {p : G × G // p.1 * p.2 = p.2 * p.1} = card (conj_classes G) * card G :=
calc card {p : G × G // p.1 * p.2 = p.2 * p.1} = card (Σ g, {h // g * h = h * g}) :
card_congr (equiv.subtype_prod_equiv_sigma_subtype (λ g h : G, g * h = h * g))
... = ∑ g, card {h // g * h = h * g} : card_sigma _
... = ∑ g, card (mul_action.fixed_by (conj_act G) G g) : sum_equiv conj_act.to_conj_act.to_equiv
_ _ (λ g, card_congr' $ congr_arg _ $ funext $ λ h, mul_inv_eq_iff_eq_mul.symm.to_eq)
... = card (quotient (mul_action.orbit_rel (conj_act G) G)) * card G :
mul_action.sum_card_fixed_by_eq_card_orbits_mul_card_group (conj_act G) G
... = card (quotient (is_conj.setoid G)) * card G :
have this : mul_action.orbit_rel (conj_act G) G = is_conj.setoid G :=
setoid.ext (λ g h, (setoid.comm' _).trans is_conj_iff.symm),
by cc
lemma comm_prob_def' : comm_prob G = card (conj_classes G) / card G :=
begin
rw [comm_prob, card_comm_eq_card_conj_classes_mul_card, nat.cast_mul, sq],
exact mul_div_mul_right (card (conj_classes G)) (card G) (nat.cast_ne_zero.mpr card_ne_zero),
end
variables {G} (H : subgroup G)
lemma subgroup.comm_prob_subgroup_le : comm_prob H ≤ comm_prob G * H.index ^ 2 :=
begin
/- After rewriting with `comm_prob_def`, we reduce to showing that `G` has at least as many
commuting pairs as `H`. -/
rw [comm_prob_def, comm_prob_def, div_le_iff, mul_assoc, ←mul_pow, ←nat.cast_mul,
H.index_mul_card, div_mul_cancel, nat.cast_le],
{ apply card_le_of_injective _ _,
exact λ p, ⟨⟨p.1.1, p.1.2⟩, subtype.ext_iff.mp p.2⟩,
exact λ p q h, by simpa only [subtype.ext_iff, prod.ext_iff] using h },
{ exact pow_ne_zero 2 (nat.cast_ne_zero.mpr card_ne_zero) },
{ exact pow_pos (nat.cast_pos.mpr card_pos) 2 },
end
lemma subgroup.comm_prob_quotient_le [H.normal] : comm_prob (G ⧸ H) ≤ comm_prob G * card H :=
begin
/- After rewriting with `comm_prob_def'`, we reduce to showing that `G` has at least as many
conjugacy classes as `G ⧸ H`. -/
rw [comm_prob_def', comm_prob_def', div_le_iff, mul_assoc, ←nat.cast_mul, mul_comm (card H),
←subgroup.card_eq_card_quotient_mul_card_subgroup, div_mul_cancel, nat.cast_le],
{ exact card_le_of_surjective (conj_classes.map (quotient_group.mk' H))
(conj_classes.map_surjective quotient.surjective_quotient_mk') },
{ exact nat.cast_ne_zero.mpr card_ne_zero },
{ exact nat.cast_pos.mpr card_pos },
end
variables (G)
lemma inv_card_commutator_le_comm_prob : (↑(card (commutator G)))⁻¹ ≤ comm_prob G :=
(inv_pos_le_iff_one_le_mul (by exact nat.cast_pos.mpr card_pos)).mpr
(le_trans (ge_of_eq (comm_prob_eq_one_iff.mpr (abelianization.comm_group G).mul_comm))
(commutator G).comm_prob_quotient_le)
|
3e4acd1046cff9bf96e86b44f58cc42508522684 | 0707842a58b971bc2c537fdcab2f5cef1c12d77a | /lean4/02_hello_world_with_main.lean | 1f7d56efa4a571e52dc7feeb2ccc302b9ff23c36 | [] | no_license | adolfont/LearningProgramming | 7a41e5dfde8df72fc0b4a23592999ecdb22a26e0 | 866e6654d347287bd0c63aa31d18705174f00324 | refs/heads/master | 1,652,902,832,503 | 1,651,315,660,000 | 1,651,315,660,000 | 1,328,601 | 2 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 98 | lean | def main : IO Unit :=
IO.println "Hello, world!"
-- lean <02_hello_world_with_main.lean> --run |
13c62f8dafb9ef2cab42dcaed1854606cffbc3e7 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/algebra/category/FinVect.lean | f3b2583d36e51432f068cb400b58fd17be5523c4 | [
"Apache-2.0"
] | permissive | jcommelin/mathlib | d8456447c36c176e14d96d9e76f39841f69d2d9b | ee8279351a2e434c2852345c51b728d22af5a156 | refs/heads/master | 1,664,782,136,488 | 1,663,638,983,000 | 1,663,638,983,000 | 132,563,656 | 0 | 0 | Apache-2.0 | 1,663,599,929,000 | 1,525,760,539,000 | Lean | UTF-8 | Lean | false | false | 5,292 | lean | /-
Copyright (c) 2021 Jakob von Raumer. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jakob von Raumer
-/
import category_theory.monoidal.rigid.basic
import category_theory.monoidal.subcategory
import linear_algebra.tensor_product_basis
import linear_algebra.coevaluation
import algebra.category.Module.monoidal
/-!
# The category of finite dimensional vector spaces
This introduces `FinVect K`, the category of finite dimensional vector spaces over a field `K`.
It is implemented as a full subcategory on a subtype of `Module K`, which inherits monoidal and
symmetric structure as `finite_dimensional K` is a monoidal predicate.
We also provide a right rigid monoidal category instance.
-/
noncomputable theory
open category_theory Module.monoidal_category
open_locale classical big_operators
universes u
variables (K : Type u) [field K]
instance monoidal_predicate_finite_dimensional :
monoidal_category.monoidal_predicate (λ V : Module.{u} K, finite_dimensional K V) :=
{ prop_id' := finite_dimensional.finite_dimensional_self K,
prop_tensor' := λ X Y hX hY, by exactI module.finite.tensor_product K X Y }
instance closed_predicate_finite_dimensional :
monoidal_category.closed_predicate (λ V : Module.{u} K, finite_dimensional K V) :=
{ prop_ihom' := λ X Y hX hY, by exactI @linear_map.finite_dimensional K _ X _ _ hX Y _ _ hY }
/-- Define `FinVect` as the subtype of `Module.{u} K` of finite dimensional vector spaces. -/
@[derive [large_category, concrete_category, monoidal_category, symmetric_category,
monoidal_closed]]
def FinVect := full_subcategory (λ (V : Module.{u} K), finite_dimensional K V)
namespace FinVect
instance finite_dimensional (V : FinVect K) : finite_dimensional K V.obj := V.property
instance : inhabited (FinVect K) := ⟨⟨Module.of K K, finite_dimensional.finite_dimensional_self K⟩⟩
/-- Lift an unbundled vector space to `FinVect K`. -/
def of (V : Type u) [add_comm_group V] [module K V] [finite_dimensional K V] : FinVect K :=
⟨Module.of K V, by { change finite_dimensional K V, apply_instance }⟩
instance : has_forget₂ (FinVect.{u} K) (Module.{u} K) :=
by { dsimp [FinVect], apply_instance, }
instance : full (forget₂ (FinVect K) (Module.{u} K)) :=
{ preimage := λ X Y f, f, }
variables (V W : FinVect K)
@[simp] lemma ihom_obj : (ihom V).obj W = FinVect.of K (V.obj →ₗ[K] W.obj) := rfl
/-- The dual module is the dual in the rigid monoidal category `FinVect K`. -/
def FinVect_dual : FinVect K :=
⟨Module.of K (module.dual K V.obj), subspace.module.dual.finite_dimensional⟩
open category_theory.monoidal_category
/-- The coevaluation map is defined in `linear_algebra.coevaluation`. -/
def FinVect_coevaluation : 𝟙_ (FinVect K) ⟶ V ⊗ (FinVect_dual K V) :=
by apply coevaluation K V.obj
lemma FinVect_coevaluation_apply_one : FinVect_coevaluation K V (1 : K) =
∑ (i : basis.of_vector_space_index K V.obj),
(basis.of_vector_space K V.obj) i ⊗ₜ[K] (basis.of_vector_space K V.obj).coord i :=
by apply coevaluation_apply_one K V.obj
/-- The evaluation morphism is given by the contraction map. -/
def FinVect_evaluation : (FinVect_dual K V) ⊗ V ⟶ 𝟙_ (FinVect K) :=
by apply contract_left K V.obj
@[simp]
lemma FinVect_evaluation_apply (f : (FinVect_dual K V).obj) (x : V.obj) :
(FinVect_evaluation K V) (f ⊗ₜ x) = f.to_fun x :=
by apply contract_left_apply f x
private theorem coevaluation_evaluation :
let V' : FinVect K := FinVect_dual K V in
(𝟙 V' ⊗ (FinVect_coevaluation K V)) ≫ (α_ V' V V').inv ≫ (FinVect_evaluation K V ⊗ 𝟙 V')
= (ρ_ V').hom ≫ (λ_ V').inv :=
by apply contract_left_assoc_coevaluation K V.obj
private theorem evaluation_coevaluation :
(FinVect_coevaluation K V ⊗ 𝟙 V)
≫ (α_ V (FinVect_dual K V) V).hom ≫ (𝟙 V ⊗ FinVect_evaluation K V)
= (λ_ V).hom ≫ (ρ_ V).inv :=
by apply contract_left_assoc_coevaluation' K V.obj
instance exact_pairing : exact_pairing V (FinVect_dual K V) :=
{ coevaluation := FinVect_coevaluation K V,
evaluation := FinVect_evaluation K V,
coevaluation_evaluation' := coevaluation_evaluation K V,
evaluation_coevaluation' := evaluation_coevaluation K V }
instance right_dual : has_right_dual V := ⟨FinVect_dual K V⟩
instance right_rigid_category : right_rigid_category (FinVect K) := { }
variables {K V}
/-- Converts and isomorphism in the category `FinVect` to a `linear_equiv` between the underlying
vector spaces. -/
def iso_to_linear_equiv {V W : FinVect K} (i : V ≅ W) : V.obj ≃ₗ[K] W.obj :=
((forget₂ (FinVect.{u} K) (Module.{u} K)).map_iso i).to_linear_equiv
lemma iso.conj_eq_conj {V W : FinVect K} (i : V ≅ W) (f : End V) :
iso.conj i f = linear_equiv.conj (iso_to_linear_equiv i) f := rfl
end FinVect
variables {K}
/-- Converts a `linear_equiv` to an isomorphism in the category `FinVect`. -/
@[simps] def linear_equiv.to_FinVect_iso
{V W : Type u} [add_comm_group V] [module K V] [finite_dimensional K V]
[add_comm_group W] [module K W] [finite_dimensional K W]
(e : V ≃ₗ[K] W) :
FinVect.of K V ≅ FinVect.of K W :=
{ hom := e.to_linear_map,
inv := e.symm.to_linear_map,
hom_inv_id' := by {ext, exact e.left_inv x},
inv_hom_id' := by {ext, exact e.right_inv x} }
|
ba5c917803ef86f4ee087281745980a40be31969 | 8b9f17008684d796c8022dab552e42f0cb6fb347 | /tests/lean/slow/path_groupoids.lean | 528f9afc9329116a52a4bbfd833d1e200b2a0a2a | [
"Apache-2.0"
] | permissive | chubbymaggie/lean | 0d06ae25f9dd396306fb02190e89422ea94afd7b | d2c7b5c31928c98f545b16420d37842c43b4ae9a | refs/heads/master | 1,611,313,622,901 | 1,430,266,839,000 | 1,430,267,083,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 24,677 | lean | -- Copyright (c) 2014 Microsoft Corporation. All rights reserved.
-- Released under Apache 2.0 license as described in the file LICENSE.
-- Author: Jeremy Avigad
-- Ported from Coq HoTT
definition id {A : Type} (a : A) := a
definition compose {A : Type} {B : Type} {C : Type} (g : B → C) (f : A → B) := λ x, g (f x)
infixr ∘ := compose
-- Path
-- ----
set_option unifier.max_steps 100000
inductive path {A : Type} (a : A) : A → Type :=
idpath : path a a
definition idpath := @path.idpath
infix `≈` := path
-- TODO: is this right?
notation x `≈`:50 y `:>`:0 A:0 := @path A x y
notation `idp`:max := idpath _ -- TODO: can we / should we use `1`?
namespace path
-- Concatenation and inverse
-- -------------------------
definition concat {A : Type} {x y z : A} (p : x ≈ y) (q : y ≈ z) : x ≈ z :=
path.rec (λu, u) q p
definition inverse {A : Type} {x y : A} (p : x ≈ y) : y ≈ x :=
path.rec (idpath x) p
infixl `⬝` := concat
postfix `^`:100 := inverse
-- In Coq, these are not needed, because concat and inv are kept transparent
definition inv_1 {A : Type} (x : A) : (idpath x)^ ≈ idpath x := idp
definition concat_11 {A : Type} (x : A) : idpath x ⬝ idpath x ≈ idpath x := idp
-- The 1-dimensional groupoid structure
-- ------------------------------------
-- The identity path is a right unit.
definition concat_p1 {A : Type} {x y : A} (p : x ≈ y) : p ⬝ idp ≈ p :=
path.rec_on p idp
-- The identity path is a right unit.
definition concat_1p {A : Type} {x y : A} (p : x ≈ y) : idp ⬝ p ≈ p :=
path.rec_on p idp
-- Concatenation is associative.
definition concat_p_pp {A : Type} {x y z t : A} (p : x ≈ y) (q : y ≈ z) (r : z ≈ t) :
p ⬝ (q ⬝ r) ≈ (p ⬝ q) ⬝ r :=
path.rec_on r (path.rec_on q idp)
definition concat_pp_p {A : Type} {x y z t : A} (p : x ≈ y) (q : y ≈ z) (r : z ≈ t) :
(p ⬝ q) ⬝ r ≈ p ⬝ (q ⬝ r) :=
path.rec_on r (path.rec_on q idp)
-- The left inverse law.
definition concat_pV {A : Type} {x y : A} (p : x ≈ y) : p ⬝ p^ ≈ idp :=
path.rec_on p idp
-- The right inverse law.
definition concat_Vp {A : Type} {x y : A} (p : x ≈ y) : p^ ⬝ p ≈ idp :=
path.rec_on p idp
-- Several auxiliary theorems about canceling inverses across associativity. These are somewhat
-- redundant, following from earlier theorems.
definition concat_V_pp {A : Type} {x y z : A} (p : x ≈ y) (q : y ≈ z) : p^ ⬝ (p ⬝ q) ≈ q :=
path.rec_on q (path.rec_on p idp)
definition concat_p_Vp {A : Type} {x y z : A} (p : x ≈ y) (q : x ≈ z) : p ⬝ (p^ ⬝ q) ≈ q :=
path.rec_on q (path.rec_on p idp)
definition concat_pp_V {A : Type} {x y z : A} (p : x ≈ y) (q : y ≈ z) : (p ⬝ q) ⬝ q^ ≈ p :=
path.rec_on q (path.rec_on p idp)
definition concat_pV_p {A : Type} {x y z : A} (p : x ≈ z) (q : y ≈ z) : (p ⬝ q^) ⬝ q ≈ p :=
path.rec_on q (take p, path.rec_on p idp) p
-- Inverse distributes over concatenation
definition inv_pp {A : Type} {x y z : A} (p : x ≈ y) (q : y ≈ z) : (p ⬝ q)^ ≈ q^ ⬝ p^ :=
path.rec_on q (path.rec_on p idp)
definition inv_Vp {A : Type} {x y z : A} (p : y ≈ x) (q : y ≈ z) : (p^ ⬝ q)^ ≈ q^ ⬝ p :=
path.rec_on q (path.rec_on p idp)
-- universe metavariables
definition inv_pV {A : Type} {x y z : A} (p : x ≈ y) (q : z ≈ y) : (p ⬝ q^)^ ≈ q ⬝ p^ :=
path.rec_on p (λq, path.rec_on q idp) q
definition inv_VV {A : Type} {x y z : A} (p : y ≈ x) (q : z ≈ y) : (p^ ⬝ q^)^ ≈ q ⬝ p :=
path.rec_on p (path.rec_on q idp)
-- Inverse is an involution.
definition inv_V {A : Type} {x y : A} (p : x ≈ y) : p^^ ≈ p :=
path.rec_on p idp
-- Theorems for moving things around in equations
-- ----------------------------------------------
definition moveR_Mp {A : Type} {x y z : A} (p : x ≈ z) (q : y ≈ z) (r : y ≈ x) :
p ≈ (r^ ⬝ q) → (r ⬝ p) ≈ q :=
have gen : Πp q, p ≈ (r^ ⬝ q) → (r ⬝ p) ≈ q, from
path.rec_on r
(take p q,
assume h : p ≈ idp^ ⬝ q,
show idp ⬝ p ≈ q, from concat_1p _ ⬝ h ⬝ concat_1p _),
gen p q
definition moveR_pM {A : Type} {x y z : A} (p : x ≈ z) (q : y ≈ z) (r : y ≈ x) :
r ≈ q ⬝ p^ → r ⬝ p ≈ q :=
path.rec_on p (take q r h, (concat_p1 _ ⬝ h ⬝ concat_p1 _)) q r
definition moveR_Vp {A : Type} {x y z : A} (p : x ≈ z) (q : y ≈ z) (r : x ≈ y) :
p ≈ r ⬝ q → r^ ⬝ p ≈ q :=
path.rec_on r (take p q h, concat_1p _ ⬝ h ⬝ concat_1p _) p q
definition moveR_pV {A : Type} {x y z : A} (p : z ≈ x) (q : y ≈ z) (r : y ≈ x) :
r ≈ q ⬝ p → r ⬝ p^ ≈ q :=
path.rec_on p (take q r h, concat_p1 _ ⬝ h ⬝ concat_p1 _) q r
definition moveL_Mp {A : Type} {x y z : A} (p : x ≈ z) (q : y ≈ z) (r : y ≈ x) :
r^ ⬝ q ≈ p → q ≈ r ⬝ p :=
path.rec_on r (take p q h, (concat_1p _)^ ⬝ h ⬝ (concat_1p _)^) p q
definition moveL_pM {A : Type} {x y z : A} (p : x ≈ z) (q : y ≈ z) (r : y ≈ x) :
q ⬝ p^ ≈ r → q ≈ r ⬝ p :=
path.rec_on p (take q r h, (concat_p1 _)^ ⬝ h ⬝ (concat_p1 _)^) q r
definition moveL_Vp {A : Type} {x y z : A} (p : x ≈ z) (q : y ≈ z) (r : x ≈ y) :
r ⬝ q ≈ p → q ≈ r^ ⬝ p :=
path.rec_on r (take p q h, (concat_1p _)^ ⬝ h ⬝ (concat_1p _)^) p q
definition moveL_pV {A : Type} {x y z : A} (p : z ≈ x) (q : y ≈ z) (r : y ≈ x) :
q ⬝ p ≈ r → q ≈ r ⬝ p^ :=
path.rec_on p (take q r h, (concat_p1 _)^ ⬝ h ⬝ (concat_p1 _)^) q r
definition moveL_1M {A : Type} {x y : A} (p q : x ≈ y) :
p ⬝ q^ ≈ idp → p ≈ q :=
path.rec_on q (take p h, (concat_p1 _)^ ⬝ h) p
definition moveL_M1 {A : Type} {x y : A} (p q : x ≈ y) :
q^ ⬝ p ≈ idp → p ≈ q :=
path.rec_on q (take p h, (concat_1p _)^ ⬝ h) p
definition moveL_1V {A : Type} {x y : A} (p : x ≈ y) (q : y ≈ x) :
p ⬝ q ≈ idp → p ≈ q^ :=
path.rec_on q (take p h, (concat_p1 _)^ ⬝ h) p
definition moveL_V1 {A : Type} {x y : A} (p : x ≈ y) (q : y ≈ x) :
q ⬝ p ≈ idp → p ≈ q^ :=
path.rec_on q (take p h, (concat_1p _)^ ⬝ h) p
definition moveR_M1 {A : Type} {x y : A} (p q : x ≈ y) :
idp ≈ p^ ⬝ q → p ≈ q :=
path.rec_on p (take q h, h ⬝ (concat_1p _)) q
definition moveR_1M {A : Type} {x y : A} (p q : x ≈ y) :
idp ≈ q ⬝ p^ → p ≈ q :=
path.rec_on p (take q h, h ⬝ (concat_p1 _)) q
definition moveR_1V {A : Type} {x y : A} (p : x ≈ y) (q : y ≈ x) :
idp ≈ q ⬝ p → p^ ≈ q :=
path.rec_on p (take q h, h ⬝ (concat_p1 _)) q
definition moveR_V1 {A : Type} {x y : A} (p : x ≈ y) (q : y ≈ x) :
idp ≈ p ⬝ q → p^ ≈ q :=
path.rec_on p (take q h, h ⬝ (concat_1p _)) q
-- Transport
-- ---------
-- keep transparent, so transport _ idp p is definitionally equal to p
definition transport {A : Type} (P : A → Type) {x y : A} (p : x ≈ y) (u : P x) : P y :=
path.rec_on p u
definition transport_1 {A : Type} (P : A → Type) {x : A} (u : P x) : transport _ idp u ≈ u :=
idp
-- TODO: is the binding strength on x reasonable? (It is modeled on the notation for subst
-- in the standard library.)
-- This idiom makes the operation right associative.
notation p `#`:65 x:64 := transport _ p x
definition ap ⦃A B : Type⦄ (f : A → B) {x y:A} (p : x ≈ y) : f x ≈ f y :=
path.rec_on p idp
-- TODO: is this better than an alias? Note use of curly brackets
definition ap01 := ap
definition pointwise_paths {A : Type} {P : A → Type} (f g : Πx, P x) : Type :=
Πx : A, f x ≈ g x
infix `∼` := pointwise_paths
definition apD10 {A} {B : A → Type} {f g : Πx, B x} (H : f ≈ g) : f ∼ g :=
λx, path.rec_on H idp
definition ap10 {A B} {f g : A → B} (H : f ≈ g) : f ∼ g := apD10 H
definition ap11 {A B} {f g : A → B} (H : f ≈ g) {x y : A} (p : x ≈ y) : f x ≈ g y :=
path.rec_on H (path.rec_on p idp)
-- TODO: Note that the next line breaks the proof!
-- opaque_hint (hiding path.rec_on)
-- set_option pp.implicit true
definition apD {A:Type} {B : A → Type} (f : Πa:A, B a) {x y : A} (p : x ≈ y) : p # (f x) ≈ f y :=
path.rec_on p idp
-- More theorems for moving things around in equations
-- ---------------------------------------------------
definition moveR_transport_p {A : Type} (P : A → Type) {x y : A} (p : x ≈ y) (u : P x) (v : P y) :
u ≈ p^ # v → p # u ≈ v :=
path.rec_on p (take u v, id) u v
definition moveR_transport_V {A : Type} (P : A → Type) {x y : A} (p : y ≈ x) (u : P x) (v : P y) :
u ≈ p # v → p^ # u ≈ v :=
path.rec_on p (take u v, id) u v
definition moveL_transport_V {A : Type} (P : A → Type) {x y : A} (p : x ≈ y) (u : P x) (v : P y) :
p # u ≈ v → u ≈ p^ # v :=
path.rec_on p (take u v, id) u v
definition moveL_transport_p {A : Type} (P : A → Type) {x y : A} (p : y ≈ x) (u : P x) (v : P y) :
p^ # u ≈ v → u ≈ p # v :=
path.rec_on p (take u v, id) u v
-- Functoriality of functions
-- --------------------------
-- Here we prove that functions behave like functors between groupoids, and that [ap] itself is
-- functorial.
-- Functions take identity paths to identity paths
definition ap_1 {A B : Type} (x : A) (f : A → B) : (ap f idp) ≈ idp :> (f x ≈ f x) := idp
definition apD_1 {A B} (x : A) (f : forall x : A, B x) : apD f idp ≈ idp :> (f x ≈ f x) := idp
-- Functions commute with concatenation.
definition ap_pp {A B : Type} (f : A → B) {x y z : A} (p : x ≈ y) (q : y ≈ z) :
ap f (p ⬝ q) ≈ (ap f p) ⬝ (ap f q) :=
path.rec_on q (path.rec_on p idp)
definition ap_p_pp {A B : Type} (f : A → B) {w x y z : A} (r : f w ≈ f x) (p : x ≈ y) (q : y ≈ z) :
r ⬝ (ap f (p ⬝ q)) ≈ (r ⬝ ap f p) ⬝ (ap f q) :=
path.rec_on p (take r q, path.rec_on q (concat_p_pp r idp idp)) r q
definition ap_pp_p {A B : Type} (f : A → B) {w x y z : A} (p : x ≈ y) (q : y ≈ z) (r : f z ≈ f w) :
(ap f (p ⬝ q)) ⬝ r ≈ (ap f p) ⬝ (ap f q ⬝ r) :=
path.rec_on p (take q, path.rec_on q (take r, concat_pp_p _ _ _)) q r
-- Functions commute with path inverses.
definition inverse_ap {A B : Type} (f : A → B) {x y : A} (p : x ≈ y) : (ap f p)^ ≈ ap f (p^) :=
path.rec_on p idp
definition ap_V {A B : Type} (f : A → B) {x y : A} (p : x ≈ y) : ap f (p^) ≈ (ap f p)^ :=
path.rec_on p idp
-- TODO: rename id to idmap?
definition ap_idmap {A : Type} {x y : A} (p : x ≈ y) : ap id p ≈ p :=
path.rec_on p idp
definition ap_compose {A B C : Type} (f : A → B) (g : B → C) {x y : A} (p : x ≈ y) :
ap (g ∘ f) p ≈ ap g (ap f p) :=
path.rec_on p idp
-- Sometimes we don't have the actual function [compose].
definition ap_compose' {A B C : Type} (f : A → B) (g : B → C) {x y : A} (p : x ≈ y) :
ap (λa, g (f a)) p ≈ ap g (ap f p) :=
path.rec_on p idp
-- The action of constant maps.
definition ap_const {A B : Type} {x y : A} (p : x ≈ y) (z : B) :
ap (λu, z) p ≈ idp :=
path.rec_on p idp
-- Naturality of [ap].
definition concat_Ap {A B : Type} {f g : A → B} (p : forall x, f x ≈ g x) {x y : A} (q : x ≈ y) :
(ap f q) ⬝ (p y) ≈ (p x) ⬝ (ap g q) :=
path.rec_on q (concat_1p _ ⬝ (concat_p1 _)^)
-- Naturality of [ap] at identity.
definition concat_A1p {A : Type} {f : A → A} (p : forall x, f x ≈ x) {x y : A} (q : x ≈ y) :
(ap f q) ⬝ (p y) ≈ (p x) ⬝ q :=
path.rec_on q (concat_1p _ ⬝ (concat_p1 _)^)
definition concat_pA1 {A : Type} {f : A → A} (p : forall x, x ≈ f x) {x y : A} (q : x ≈ y) :
(p x) ⬝ (ap f q) ≈ q ⬝ (p y) :=
path.rec_on q (concat_p1 _ ⬝ (concat_1p _)^)
--TODO: note that the Coq proof for the preceding is
--
-- match q as i in (_ ≈ y) return (p x ⬝ ap f i ≈ i ⬝ p y) with
-- | idpath => concat_p1 _ ⬝ (concat_1p _)^
-- end.
--
-- It is nice that we don't have to give the predicate.
-- Naturality with other paths hanging around.
definition concat_pA_pp {A B : Type} {f g : A → B} (p : forall x, f x ≈ g x)
{x y : A} (q : x ≈ y)
{w z : B} (r : w ≈ f x) (s : g y ≈ z) :
(r ⬝ ap f q) ⬝ (p y ⬝ s) ≈ (r ⬝ p x) ⬝ (ap g q ⬝ s) :=
path.rec_on q (take s, path.rec_on s (take r, idp)) s r
-- Action of [apD10] and [ap10] on paths
-- -------------------------------------
-- Application of paths between functions preserves the groupoid structure
definition apD10_1 {A} {B : A → Type} (f : Πx, B x) (x : A) : apD10 (idpath f) x ≈ idp := idp
definition apD10_pp {A} {B : A → Type} {f f' f'' : Πx, B x} (h : f ≈ f') (h' : f' ≈ f'') (x : A) :
apD10 (h ⬝ h') x ≈ apD10 h x ⬝ apD10 h' x :=
path.rec_on h (take h', path.rec_on h' idp) h'
definition apD10_V {A : Type} {B : A → Type} {f g : Πx : A, B x} (h : f ≈ g) (x : A) :
apD10 (h^) x ≈ (apD10 h x)^ :=
path.rec_on h idp
definition ap10_1 {A B} {f : A → B} (x : A) : ap10 (idpath f) x ≈ idp := idp
definition ap10_pp {A B} {f f' f'' : A → B} (h : f ≈ f') (h' : f' ≈ f'') (x : A) :
ap10 (h ⬝ h') x ≈ ap10 h x ⬝ ap10 h' x := apD10_pp h h' x
definition ap10_V {A B} {f g : A→B} (h : f ≈ g) (x:A) : ap10 (h^) x ≈ (ap10 h x)^ := apD10_V h x
-- [ap10] also behaves nicely on paths produced by [ap]
definition ap_ap10 {A B C} (f g : A → B) (h : B → C) (p : f ≈ g) (a : A) :
ap h (ap10 p a) ≈ ap10 (ap (λ f', h ∘ f') p) a:=
path.rec_on p idp
-- Transport and the groupoid structure of paths
-- ---------------------------------------------
-- TODO: move from above?
-- definition transport_1 {A : Type} (P : A → Type) {x : A} (u : P x)
-- : idp # u ≈ u := idp
definition transport_pp {A : Type} (P : A → Type) {x y z : A} (p : x ≈ y) (q : y ≈ z) (u : P x) :
p ⬝ q # u ≈ q # p # u :=
path.rec_on q (path.rec_on p idp)
definition transport_pV {A : Type} (P : A → Type) {x y : A} (p : x ≈ y) (z : P y) :
p # p^ # z ≈ z :=
(transport_pp P (p^) p z)^ ⬝ ap (λr, transport P r z) (concat_Vp p)
definition transport_Vp {A : Type} (P : A → Type) {x y : A} (p : x ≈ y) (z : P x) :
p^ # p # z ≈ z :=
(transport_pp P p (p^) z)^ ⬝ ap (λr, transport P r z) (concat_pV p)
-----------------------------------------------
-- *** Examples of difficult induction problems
-----------------------------------------------
theorem double_induction
{A : Type} {x y z : A} (p : x ≈ y) (q : y ≈ z)
{C : Π(x y z : A), Π(p : x ≈ y), Π(q : y ≈ z), Type}
(H : C x x x (idpath x) (idpath x)) :
C x y z p q :=
path.rec_on p (take z q, path.rec_on q H) z q
theorem double_induction2
{A : Type} {x y z : A} (p : x ≈ y) (q : z ≈ y)
{C : Π(x y z : A), Π(p : x ≈ y), Π(q : z ≈ y), Type}
(H : C z z z (idpath z) (idpath z)) :
C x y z p q :=
path.rec_on p (take y q, path.rec_on q H) y q
theorem double_induction2'
{A : Type} {x y z : A} (p : x ≈ y) (q : z ≈ y)
{C : Π(x y z : A), Π(p : x ≈ y), Π(q : z ≈ y), Type}
(H : C z z z (idpath z) (idpath z)) : C x y z p q :=
path.rec_on p (take y q, path.rec_on q H) y q
theorem triple_induction
{A : Type} {x y z w : A} (p : x ≈ y) (q : y ≈ z) (r : z ≈ w)
{C : Π(x y z w : A), Π(p : x ≈ y), Π(q : y ≈ z), Π(r: z ≈ w), Type}
(H : C x x x x (idpath x) (idpath x) (idpath x)) :
C x y z w p q r :=
path.rec_on p (take z q, path.rec_on q (take w r, path.rec_on r H)) z q w r
-- try this again
definition concat_pV_p_new {A : Type} {x y z : A} (p : x ≈ z) (q : y ≈ z) : (p ⬝ q^) ⬝ q ≈ p :=
double_induction2 p q idp
definition transport_p_pp {A : Type} (P : A → Type)
{x y z w : A} (p : x ≈ y) (q : y ≈ z) (r : z ≈ w) (u : P x) :
ap (λe, e # u) (concat_p_pp p q r) ⬝ (transport_pp P (p ⬝ q) r u) ⬝
ap (transport P r) (transport_pp P p q u)
≈ (transport_pp P p (q ⬝ r) u) ⬝ (transport_pp P q r (p # u))
:> ((p ⬝ (q ⬝ r)) # u ≈ r # q # p # u) :=
triple_induction p q r (take u, idp) u
-- Here is another coherence lemma for transport.
definition transport_pVp {A} (P : A → Type) {x y : A} (p : x ≈ y) (z : P x) :
transport_pV P p (transport P p z) ≈ ap (transport P p) (transport_Vp P p z)
:= path.rec_on p idp
-- Dependent transport in a doubly dependent type.
definition transportD {A : Type} (B : A → Type) (C : Π a : A, B a → Type)
{x1 x2 : A} (p : x1 ≈ x2) (y : B x1) (z : C x1 y) :
C x2 (p # y) :=
path.rec_on p z
-- Transporting along higher-dimensional paths
definition transport2 {A : Type} (P : A → Type) {x y : A} {p q : x ≈ y} (r : p ≈ q) (z : P x) :
p # z ≈ q # z := ap (λp', p' # z) r
-- An alternative definition.
definition transport2_is_ap10 {A : Type} (Q : A → Type) {x y : A} {p q : x ≈ y} (r : p ≈ q)
(z : Q x) :
transport2 Q r z ≈ ap10 (ap (transport Q) r) z :=
path.rec_on r idp
definition transport2_p2p {A : Type} (P : A → Type) {x y : A} {p1 p2 p3 : x ≈ y}
(r1 : p1 ≈ p2) (r2 : p2 ≈ p3) (z : P x) :
transport2 P (r1 ⬝ r2) z ≈ transport2 P r1 z ⬝ transport2 P r2 z :=
path.rec_on r1 (path.rec_on r2 idp)
-- TODO: another interesting case
definition transport2_V {A : Type} (Q : A → Type) {x y : A} {p q : x ≈ y} (r : p ≈ q) (z : Q x) :
transport2 Q (r^) z ≈ ((transport2 Q r z)^) :=
-- path.rec_on r idp -- doesn't work
path.rec_on r (idpath (inverse (transport2 Q (idpath p) z)))
definition concat_AT {A : Type} (P : A → Type) {x y : A} {p q : x ≈ y} {z w : P x} (r : p ≈ q)
(s : z ≈ w) :
ap (transport P p) s ⬝ transport2 P r w ≈ transport2 P r z ⬝ ap (transport P q) s :=
path.rec_on r (concat_p1 _ ⬝ (concat_1p _)^)
-- TODO (from Coq library): What should this be called?
definition ap_transport {A} {P Q : A → Type} {x y : A} (p : x ≈ y) (f : Πx, P x → Q x) (z : P x) :
f y (p # z) ≈ (p # (f x z)) :=
path.rec_on p idp
-- Transporting in particular fibrations
-- -------------------------------------
/-
From the Coq HoTT library:
One frequently needs lemmas showing that transport in a certain dependent type is equal to some
more explicitly defined operation, defined according to the structure of that dependent type.
For most dependent types, we prove these lemmas in the appropriate file in the types/
subdirectory. Here we consider only the most basic cases.
-/
-- Transporting in a constant fibration.
definition transport_const {A B : Type} {x1 x2 : A} (p : x1 ≈ x2) (y : B) :
transport (λx, B) p y ≈ y :=
path.rec_on p idp
definition transport2_const {A B : Type} {x1 x2 : A} {p q : x1 ≈ x2} (r : p ≈ q) (y : B) :
transport_const p y ≈ transport2 (λu, B) r y ⬝ transport_const q y :=
path.rec_on r (concat_1p _)^
-- Transporting in a pulled back fibration.
definition transport_compose {A B} {x y : A} (P : B → Type) (f : A → B) (p : x ≈ y) (z : P (f x)) :
transport (λx, P (f x)) p z ≈ transport P (ap f p) z :=
path.rec_on p idp
definition transport_precompose {A B C} (f : A → B) (g g' : B → C) (p : g ≈ g') :
transport (λh : B → C, g ∘ f ≈ h ∘ f) p idp ≈ ap (λh, h ∘ f) p :=
path.rec_on p idp
definition apD10_ap_precompose {A B C} (f : A → B) (g g' : B → C) (p : g ≈ g') (a : A) :
apD10 (ap (λh : B → C, h ∘ f) p) a ≈ apD10 p (f a) :=
path.rec_on p idp
definition apD10_ap_postcompose {A B C} (f : B → C) (g g' : A → B) (p : g ≈ g') (a : A) :
apD10 (ap (λh : A → B, f ∘ h) p) a ≈ ap f (apD10 p a) :=
path.rec_on p idp
-- TODO: another example where a term has to be given explicitly
-- A special case of [transport_compose] which seems to come up a lot.
definition transport_idmap_ap A (P : A → Type) x y (p : x ≈ y) (u : P x) :
transport P p u ≈ transport (λz, z) (ap P p) u :=
path.rec_on p (idpath (transport (λ (z : Type), z) (ap P (idpath x)) u))
-- The behavior of [ap] and [apD]
-- ------------------------------
-- In a constant fibration, [apD] reduces to [ap], modulo [transport_const].
definition apD_const {A B} {x y : A} (f : A → B) (p: x ≈ y) :
apD f p ≈ transport_const p (f x) ⬝ ap f p :=
path.rec_on p idp
-- The 2-dimensional groupoid structure
-- ------------------------------------
-- Horizontal composition of 2-dimensional paths.
definition concat2 {A} {x y z : A} {p p' : x ≈ y} {q q' : y ≈ z} (h : p ≈ p') (h' : q ≈ q') :
p ⬝ q ≈ p' ⬝ q' :=
path.rec_on h (path.rec_on h' idp)
infixl `⬝⬝`:75 := concat2
-- 2-dimensional path inversion
definition inverse2 {A : Type} {x y : A} {p q : x ≈ y} (h : p ≈ q) : p^ ≈ q^ :=
path.rec_on h idp
-- Whiskering
-- ----------
definition whiskerL {A : Type} {x y z : A} (p : x ≈ y) {q r : y ≈ z} (h : q ≈ r) : p ⬝ q ≈ p ⬝ r :=
idp ⬝⬝ h
definition whiskerR {A : Type} {x y z : A} {p q : x ≈ y} (h : p ≈ q) (r : y ≈ z) : p ⬝ r ≈ q ⬝ r :=
h ⬝⬝ idp
-- Unwhiskering, a.k.a. cancelling
-- -------------------------------
definition cancelL {A} {x y z : A} (p : x ≈ y) (q r : y ≈ z) : (p ⬝ q ≈ p ⬝ r) → (q ≈ r) :=
path.rec_on p (take r, path.rec_on r (take q a, (concat_1p q)^ ⬝ a)) r q
definition cancelR {A} {x y z : A} (p q : x ≈ y) (r : y ≈ z) : (p ⬝ r ≈ q ⬝ r) → (p ≈ q) :=
path.rec_on r (take p, path.rec_on p (take q a, a ⬝ concat_p1 q)) p q
-- Whiskering and identity paths.
definition whiskerR_p1 {A : Type} {x y : A} {p q : x ≈ y} (h : p ≈ q) :
(concat_p1 p)^ ⬝ whiskerR h idp ⬝ concat_p1 q ≈ h :=
path.rec_on h (path.rec_on p idp)
definition whiskerR_1p {A : Type} {x y z : A} (p : x ≈ y) (q : y ≈ z) :
whiskerR idp q ≈ idp :> (p ⬝ q ≈ p ⬝ q) :=
path.rec_on q idp
definition whiskerL_p1 {A : Type} {x y z : A} (p : x ≈ y) (q : y ≈ z) :
whiskerL p idp ≈ idp :> (p ⬝ q ≈ p ⬝ q) :=
path.rec_on q idp
definition whiskerL_1p {A : Type} {x y : A} {p q : x ≈ y} (h : p ≈ q) :
(concat_1p p) ^ ⬝ whiskerL idp h ⬝ concat_1p q ≈ h :=
path.rec_on h (path.rec_on p idp)
definition concat2_p1 {A : Type} {x y : A} {p q : x ≈ y} (h : p ≈ q) :
h ⬝⬝ idp ≈ whiskerR h idp :> (p ⬝ idp ≈ q ⬝ idp) :=
path.rec_on h idp
definition concat2_1p {A : Type} {x y : A} {p q : x ≈ y} (h : p ≈ q) :
idp ⬝⬝ h ≈ whiskerL idp h :> (idp ⬝ p ≈ idp ⬝ q) :=
path.rec_on h idp
-- TODO: note, 4 inductions
-- The interchange law for concatenation.
definition concat_concat2 {A : Type} {x y z : A} {p p' p'' : x ≈ y} {q q' q'' : y ≈ z}
(a : p ≈ p') (b : p' ≈ p'') (c : q ≈ q') (d : q' ≈ q'') :
(a ⬝⬝ c) ⬝ (b ⬝⬝ d) ≈ (a ⬝ b) ⬝⬝ (c ⬝ d) :=
path.rec_on d (path.rec_on c (path.rec_on b (path.rec_on a idp)))
definition concat_whisker {A} {x y z : A} (p p' : x ≈ y) (q q' : y ≈ z) (a : p ≈ p') (b : q ≈ q') :
(whiskerR a q) ⬝ (whiskerL p' b) ≈ (whiskerL p b) ⬝ (whiskerR a q') :=
path.rec_on b (path.rec_on a (concat_1p _)^)
-- Structure corresponding to the coherence equations of a bicategory.
-- The "pentagonator": the 3-cell witnessing the associativity pentagon.
definition pentagon {A : Type} {v w x y z : A} (p : v ≈ w) (q : w ≈ x) (r : x ≈ y) (s : y ≈ z) :
whiskerL p (concat_p_pp q r s)
⬝ concat_p_pp p (q ⬝ r) s
⬝ whiskerR (concat_p_pp p q r) s
≈ concat_p_pp p q (r ⬝ s) ⬝ concat_p_pp (p ⬝ q) r s :=
path.rec_on p (take q, path.rec_on q (take r, path.rec_on r (take s, path.rec_on s idp))) q r s
-- The 3-cell witnessing the left unit triangle.
definition triangulator {A : Type} {x y z : A} (p : x ≈ y) (q : y ≈ z) :
concat_p_pp p idp q ⬝ whiskerR (concat_p1 p) q ≈ whiskerL p (concat_1p q) :=
path.rec_on p (take q, path.rec_on q idp) q
definition eckmann_hilton {A : Type} {x:A} (p q : idp ≈ idp :> (x ≈ x)) : p ⬝ q ≈ q ⬝ p :=
(whiskerR_p1 p ⬝⬝ whiskerL_1p q)^
⬝ (concat_p1 _ ⬝⬝ concat_p1 _)
⬝ (concat_1p _ ⬝⬝ concat_1p _)
⬝ (concat_whisker _ _ _ _ p q)
⬝ (concat_1p _ ⬝⬝ concat_1p _)^
⬝ (concat_p1 _ ⬝⬝ concat_p1 _)^
⬝ (whiskerL_1p q ⬝⬝ whiskerR_p1 p)
-- The action of functions on 2-dimensional paths
definition ap02 {A B : Type} (f:A → B) {x y : A} {p q : x ≈ y} (r : p ≈ q) : ap f p ≈ ap f q :=
path.rec_on r idp
definition ap02_pp {A B} (f : A → B) {x y : A} {p p' p'' : x ≈ y} (r : p ≈ p') (r' : p' ≈ p'') :
ap02 f (r ⬝ r') ≈ ap02 f r ⬝ ap02 f r' :=
path.rec_on r (path.rec_on r' idp)
definition ap02_p2p {A B} (f : A→B) {x y z : A} {p p' : x ≈ y} {q q' :y ≈ z} (r : p ≈ p')
(s : q ≈ q') :
ap02 f (r ⬝⬝ s) ≈ ap_pp f p q
⬝ (ap02 f r ⬝⬝ ap02 f s)
⬝ (ap_pp f p' q')^ :=
path.rec_on r (path.rec_on s (path.rec_on q (path.rec_on p idp)))
definition apD02 {A : Type} {B : A → Type} {x y : A} {p q : x ≈ y} (f : Π x, B x) (r : p ≈ q) :
apD f p ≈ transport2 B r (f x) ⬝ apD f q :=
path.rec_on r (concat_1p _)^
end path
|
f8ab7c07377426cd4110535a1762734d12f0a6db | 63abd62053d479eae5abf4951554e1064a4c45b4 | /test/apply_fun.lean | b50a63693c01ba19e9848bfb43d2e7ee272c98ff | [
"Apache-2.0"
] | permissive | Lix0120/mathlib | 0020745240315ed0e517cbf32e738d8f9811dd80 | e14c37827456fc6707f31b4d1d16f1f3a3205e91 | refs/heads/master | 1,673,102,855,024 | 1,604,151,044,000 | 1,604,151,044,000 | 308,930,245 | 0 | 0 | Apache-2.0 | 1,604,164,710,000 | 1,604,163,547,000 | null | UTF-8 | Lean | false | false | 1,196 | lean | import tactic.apply_fun
import data.matrix.basic
open function
example (X Y Z : Type) (f : X → Y) (g : Y → Z) (H : injective $ g ∘ f) :
injective f :=
begin
intros x x' h,
apply_fun g at h,
exact H h
end
example (f : ℕ → ℕ) (a b : ℕ) (monof : monotone f) (h : a ≤ b) : f a ≤ f b :=
begin
apply_fun f at h,
assumption,
assumption
end
example (a b : ℤ) (h : a = b) : a + 1 = b + 1 :=
begin
apply_fun (λ n, n+1) at h,
-- check that `h` was β-reduced
guard_hyp' h : a + 1 = b + 1,
exact h
end
example (f : ℕ → ℕ) (a b : ℕ) (monof : monotone f) (h : a ≤ b) : f a ≤ f b :=
begin
apply_fun f at h using monof,
assumption
end
-- monotonicity will be proved by `mono` in the next example
example (a b : ℕ) (h : a ≤ b) : a + 1 ≤ b + 1 :=
begin
apply_fun (λ n, n+1) at h,
exact h
end
example {n : Type} [fintype n] {X : Type} [semiring X]
(f : matrix n n X → matrix n n X) (A B : matrix n n X) (h : A * B = 0) : f (A * B) = f 0 :=
begin
apply_fun f at h,
-- check that our β-reduction didn't mess things up:
-- (previously `apply_fun` was producing `f (A.mul B) = f 0`)
guard_hyp' h : f (A * B) = f 0,
exact h,
end
|
4a5595006770fb8c5e1e7215b72391a33308ccfa | 54ce0561cebde424526f41d45f490ed56be2bd0c | /src/game/ch4_Integers_and_Rationals/4_Gaps_in_the_Rationals.lean | d53a5693a97b5b27c13f38ac9dbbef2b162ad8ed | [] | no_license | melembroucarlitos/Tao_Analysis-LEAN | cf7b3298d317891a09e4bf21cfe7c7ffcb57b9a9 | 3f4fc7e090d96b6cef64896492fba4bef124794b | refs/heads/master | 1,692,952,385,694 | 1,636,287,522,000 | 1,636,287,522,000 | 400,630,166 | 3 | 0 | null | 1,635,910,807,000 | 1,630,096,823,000 | Lean | UTF-8 | Lean | false | false | 172 | lean | -- Level name : Gaps in the Rationals
/-
# Hey yall
## This is just to a placeholder to make sure all is working
these are some words
and these are some other words
-/
|
e51c98eaff78db3ae6b2a880f31b83669cafc9d4 | d436468d80b739ba7e06843c4d0d2070e43448e5 | /src/data/real/basic.lean | cf57b47668c51c954e77c43d2e5e2af64eeaa9d2 | [
"Apache-2.0"
] | permissive | roro47/mathlib | 761fdc002aef92f77818f3fef06bf6ec6fc1a28e | 80aa7d52537571a2ca62a3fdf71c9533a09422cf | refs/heads/master | 1,599,656,410,625 | 1,573,649,488,000 | 1,573,649,488,000 | 221,452,951 | 0 | 0 | Apache-2.0 | 1,573,647,693,000 | 1,573,647,692,000 | null | UTF-8 | Lean | false | false | 26,079 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro, Floris van Doorn
The (classical) real numbers ℝ. This is a direct construction
from Cauchy sequences.
-/
import order.conditionally_complete_lattice data.real.cau_seq_completion
algebra.archimedean order.bounds
def real := @cau_seq.completion.Cauchy ℚ _ _ _ abs _
notation `ℝ` := real
namespace real
open cau_seq cau_seq.completion
variables {x y : ℝ}
def of_rat (x : ℚ) : ℝ := of_rat x
def mk (x : cau_seq ℚ abs) : ℝ := cau_seq.completion.mk x
def comm_ring_aux : comm_ring ℝ := cau_seq.completion.comm_ring
instance : comm_ring ℝ := { ..comm_ring_aux }
/- Extra instances to short-circuit type class resolution -/
instance : ring ℝ := by apply_instance
instance : comm_semiring ℝ := by apply_instance
instance : semiring ℝ := by apply_instance
instance : add_comm_group ℝ := by apply_instance
instance : add_group ℝ := by apply_instance
instance : add_comm_monoid ℝ := by apply_instance
instance : add_monoid ℝ := by apply_instance
instance : add_left_cancel_semigroup ℝ := by apply_instance
instance : add_right_cancel_semigroup ℝ := by apply_instance
instance : add_comm_semigroup ℝ := by apply_instance
instance : add_semigroup ℝ := by apply_instance
instance : comm_monoid ℝ := by apply_instance
instance : monoid ℝ := by apply_instance
instance : comm_semigroup ℝ := by apply_instance
instance : semigroup ℝ := by apply_instance
instance : inhabited ℝ := ⟨0⟩
theorem of_rat_sub (x y : ℚ) : of_rat (x - y) = of_rat x - of_rat y :=
congr_arg mk (const_sub _ _)
instance : has_lt ℝ :=
⟨λ x y, quotient.lift_on₂ x y (<) $
λ f₁ g₁ f₂ g₂ hf hg, propext $
⟨λ h, lt_of_eq_of_lt (setoid.symm hf) (lt_of_lt_of_eq h hg),
λ h, lt_of_eq_of_lt hf (lt_of_lt_of_eq h (setoid.symm hg))⟩⟩
@[simp] theorem mk_lt {f g : cau_seq ℚ abs} : mk f < mk g ↔ f < g := iff.rfl
theorem mk_eq {f g : cau_seq ℚ abs} : mk f = mk g ↔ f ≈ g := mk_eq
theorem quotient_mk_eq_mk (f : cau_seq ℚ abs) : ⟦f⟧ = mk f := rfl
theorem mk_eq_mk {f : cau_seq ℚ abs} : cau_seq.completion.mk f = mk f := rfl
@[simp] theorem mk_pos {f : cau_seq ℚ abs} : 0 < mk f ↔ pos f :=
iff_of_eq (congr_arg pos (sub_zero f))
protected def le (x y : ℝ) : Prop := x < y ∨ x = y
instance : has_le ℝ := ⟨real.le⟩
@[simp] theorem mk_le {f g : cau_seq ℚ abs} : mk f ≤ mk g ↔ f ≤ g :=
or_congr iff.rfl quotient.eq
theorem add_lt_add_iff_left {a b : ℝ} (c : ℝ) : c + a < c + b ↔ a < b :=
quotient.induction_on₃ a b c (λ f g h,
iff_of_eq (congr_arg pos $ by rw add_sub_add_left_eq_sub))
instance : linear_order ℝ :=
{ le := (≤), lt := (<),
le_refl := λ a, or.inr rfl,
le_trans := λ a b c, quotient.induction_on₃ a b c $
λ f g h, by simpa [quotient_mk_eq_mk] using le_trans,
lt_iff_le_not_le := λ a b, quotient.induction_on₂ a b $
λ f g, by simpa [quotient_mk_eq_mk] using lt_iff_le_not_le,
le_antisymm := λ a b, quotient.induction_on₂ a b $
λ f g, by simpa [mk_eq, quotient_mk_eq_mk] using @cau_seq.le_antisymm _ _ f g,
le_total := λ a b, quotient.induction_on₂ a b $
λ f g, by simpa [quotient_mk_eq_mk] using le_total f g }
instance : partial_order ℝ := by apply_instance
instance : preorder ℝ := by apply_instance
theorem of_rat_lt {x y : ℚ} : of_rat x < of_rat y ↔ x < y := const_lt
protected theorem zero_lt_one : (0 : ℝ) < 1 := of_rat_lt.2 zero_lt_one
protected theorem mul_pos {a b : ℝ} : 0 < a → 0 < b → 0 < a * b :=
quotient.induction_on₂ a b $ λ f g,
show pos (f - 0) → pos (g - 0) → pos (f * g - 0),
by simpa using cau_seq.mul_pos
instance : linear_ordered_comm_ring ℝ :=
{ add_le_add_left := λ a b h c,
(le_iff_le_iff_lt_iff_lt.2 $ real.add_lt_add_iff_left c).2 h,
zero_ne_one := ne_of_lt real.zero_lt_one,
mul_nonneg := λ a b a0 b0,
match a0, b0 with
| or.inl a0, or.inl b0 := le_of_lt (real.mul_pos a0 b0)
| or.inr a0, _ := by simp [a0.symm]
| _, or.inr b0 := by simp [b0.symm]
end,
mul_pos := @real.mul_pos,
zero_lt_one := real.zero_lt_one,
add_lt_add_left := λ a b h c, (real.add_lt_add_iff_left c).2 h,
..real.comm_ring, ..real.linear_order }
/- Extra instances to short-circuit type class resolution -/
instance : linear_ordered_ring ℝ := by apply_instance
instance : ordered_ring ℝ := by apply_instance
instance : linear_ordered_semiring ℝ := by apply_instance
instance : ordered_semiring ℝ := by apply_instance
instance : ordered_comm_group ℝ := by apply_instance
instance : ordered_cancel_comm_monoid ℝ := by apply_instance
instance : ordered_comm_monoid ℝ := by apply_instance
instance : domain ℝ := by apply_instance
open_locale classical
noncomputable instance : discrete_linear_ordered_field ℝ :=
{ decidable_le := by apply_instance,
..real.linear_ordered_comm_ring,
..real.domain,
..cau_seq.completion.discrete_field }
/- Extra instances to short-circuit type class resolution -/
noncomputable instance : linear_ordered_field ℝ := by apply_instance
noncomputable instance : decidable_linear_ordered_comm_ring ℝ := by apply_instance
noncomputable instance : decidable_linear_ordered_semiring ℝ := by apply_instance
noncomputable instance : decidable_linear_ordered_comm_group ℝ := by apply_instance
noncomputable instance discrete_field : discrete_field ℝ := by apply_instance
noncomputable instance : field ℝ := by apply_instance
noncomputable instance : division_ring ℝ := by apply_instance
noncomputable instance : integral_domain ℝ := by apply_instance
noncomputable instance : nonzero_comm_ring ℝ := by apply_instance
noncomputable instance : decidable_linear_order ℝ := by apply_instance
noncomputable instance : lattice.distrib_lattice ℝ := by apply_instance
noncomputable instance : lattice.lattice ℝ := by apply_instance
noncomputable instance : lattice.semilattice_inf ℝ := by apply_instance
noncomputable instance : lattice.semilattice_sup ℝ := by apply_instance
noncomputable instance : lattice.has_inf ℝ := by apply_instance
noncomputable instance : lattice.has_sup ℝ := by apply_instance
lemma le_of_forall_epsilon_le {a b : real} (h : ∀ε, ε > 0 → a ≤ b + ε) : a ≤ b :=
le_of_forall_le_of_dense $ assume x hxb,
calc a ≤ b + (x - b) : h (x-b) $ sub_pos.2 hxb
... = x : by rw [add_comm]; simp
open rat
@[simp] theorem of_rat_eq_cast : ∀ x : ℚ, of_rat x = x :=
eq_cast of_rat rfl of_rat_add of_rat_mul
theorem le_mk_of_forall_le {f : cau_seq ℚ abs} :
(∃ i, ∀ j ≥ i, x ≤ f j) → x ≤ mk f :=
quotient.induction_on x $ λ g h, le_of_not_lt $
λ ⟨K, K0, hK⟩,
let ⟨i, H⟩ := exists_forall_ge_and h $
exists_forall_ge_and hK (f.cauchy₃ $ half_pos K0) in
begin
apply not_lt_of_le (H _ (le_refl _)).1,
rw ← of_rat_eq_cast,
refine ⟨_, half_pos K0, i, λ j ij, _⟩,
have := add_le_add (H _ ij).2.1
(le_of_lt (abs_lt.1 $ (H _ (le_refl _)).2.2 _ ij).1),
rwa [← sub_eq_add_neg, sub_self_div_two, sub_apply, sub_add_sub_cancel] at this
end
theorem mk_le_of_forall_le {f : cau_seq ℚ abs} {x : ℝ} :
(∃ i, ∀ j ≥ i, (f j : ℝ) ≤ x) → mk f ≤ x
| ⟨i, H⟩ := by rw [← neg_le_neg_iff, ← mk_eq_mk, mk_neg]; exact
le_mk_of_forall_le ⟨i, λ j ij, by simp [H _ ij]⟩
theorem mk_near_of_forall_near {f : cau_seq ℚ abs} {x : ℝ} {ε : ℝ}
(H : ∃ i, ∀ j ≥ i, abs ((f j : ℝ) - x) ≤ ε) : abs (mk f - x) ≤ ε :=
abs_sub_le_iff.2
⟨sub_le_iff_le_add'.2 $ mk_le_of_forall_le $
H.imp $ λ i h j ij, sub_le_iff_le_add'.1 (abs_sub_le_iff.1 $ h j ij).1,
sub_le.1 $ le_mk_of_forall_le $
H.imp $ λ i h j ij, sub_le.1 (abs_sub_le_iff.1 $ h j ij).2⟩
instance : archimedean ℝ :=
archimedean_iff_rat_le.2 $ λ x, quotient.induction_on x $ λ f,
let ⟨M, M0, H⟩ := f.bounded' 0 in
⟨M, mk_le_of_forall_le ⟨0, λ i _,
rat.cast_le.2 $ le_of_lt (abs_lt.1 (H i)).2⟩⟩
/- mark `real` irreducible in order to prevent `auto_cases` unfolding reals,
since users rarely want to consider real numbers as Cauchy sequences.
Marking `comm_ring_aux` `irreducible` is done to ensure that there are no problems
with non definitionally equal instances, caused by making `real` irreducible-/
attribute [irreducible] real comm_ring_aux
noncomputable instance : floor_ring ℝ := archimedean.floor_ring _
theorem is_cau_seq_iff_lift {f : ℕ → ℚ} : is_cau_seq abs f ↔ is_cau_seq abs (λ i, (f i : ℝ)) :=
⟨λ H ε ε0,
let ⟨δ, δ0, δε⟩ := exists_pos_rat_lt ε0 in
(H _ δ0).imp $ λ i hi j ij, lt_trans
(by simpa using (@rat.cast_lt ℝ _ _ _).2 (hi _ ij)) δε,
λ H ε ε0, (H _ (rat.cast_pos.2 ε0)).imp $
λ i hi j ij, (@rat.cast_lt ℝ _ _ _).1 $ by simpa using hi _ ij⟩
theorem of_near (f : ℕ → ℚ) (x : ℝ)
(h : ∀ ε > 0, ∃ i, ∀ j ≥ i, abs ((f j : ℝ) - x) < ε) :
∃ h', real.mk ⟨f, h'⟩ = x :=
⟨is_cau_seq_iff_lift.2 (of_near _ (const abs x) h),
sub_eq_zero.1 $ abs_eq_zero.1 $
eq_of_le_of_forall_le_of_dense (abs_nonneg _) $ λ ε ε0,
mk_near_of_forall_near $
(h _ ε0).imp (λ i h j ij, le_of_lt (h j ij))⟩
theorem exists_floor (x : ℝ) : ∃ (ub : ℤ), (ub:ℝ) ≤ x ∧
∀ (z : ℤ), (z:ℝ) ≤ x → z ≤ ub :=
int.exists_greatest_of_bdd
(let ⟨n, hn⟩ := exists_int_gt x in ⟨n, λ z h',
int.cast_le.1 $ le_trans h' $ le_of_lt hn⟩)
(let ⟨n, hn⟩ := exists_int_lt x in ⟨n, le_of_lt hn⟩)
theorem exists_sup (S : set ℝ) : (∃ x, x ∈ S) → (∃ x, ∀ y ∈ S, y ≤ x) →
∃ x, ∀ y, x ≤ y ↔ ∀ z ∈ S, z ≤ y
| ⟨L, hL⟩ ⟨U, hU⟩ := begin
choose f hf using begin
refine λ d : ℕ, @int.exists_greatest_of_bdd
(λ n, ∃ y ∈ S, (n:ℝ) ≤ y * d) _ _ _,
{ cases exists_int_gt U with k hk,
refine ⟨k * d, λ z h, _⟩,
rcases h with ⟨y, yS, hy⟩,
refine int.cast_le.1 (le_trans hy _),
simp,
exact mul_le_mul_of_nonneg_right
(le_trans (hU _ yS) (le_of_lt hk)) (nat.cast_nonneg _) },
{ exact ⟨⌊L * d⌋, L, hL, floor_le _⟩ }
end,
have hf₁ : ∀ n > 0, ∃ y ∈ S, ((f n / n:ℚ):ℝ) ≤ y := λ n n0,
let ⟨y, yS, hy⟩ := (hf n).1 in
⟨y, yS, by simpa using (div_le_iff ((nat.cast_pos.2 n0):((_:ℝ) < _))).2 hy⟩,
have hf₂ : ∀ (n > 0) (y ∈ S), (y - (n:ℕ)⁻¹ : ℝ) < (f n / n:ℚ),
{ intros n n0 y yS,
have := lt_of_lt_of_le (sub_one_lt_floor _)
(int.cast_le.2 $ (hf n).2 _ ⟨y, yS, floor_le _⟩),
simp [-sub_eq_add_neg],
rwa [lt_div_iff ((nat.cast_pos.2 n0):((_:ℝ) < _)), sub_mul, _root_.inv_mul_cancel],
exact ne_of_gt (nat.cast_pos.2 n0) },
suffices hg, let g : cau_seq ℚ abs := ⟨λ n, f n / n, hg⟩,
refine ⟨mk g, λ y, ⟨λ h x xS, le_trans _ h, λ h, _⟩⟩,
{ refine le_of_forall_ge_of_dense (λ z xz, _),
cases exists_nat_gt (x - z)⁻¹ with K hK,
refine le_mk_of_forall_le ⟨K, λ n nK, _⟩,
replace xz := sub_pos.2 xz,
replace hK := le_trans (le_of_lt hK) (nat.cast_le.2 nK),
have n0 : 0 < n := nat.cast_pos.1 (lt_of_lt_of_le (inv_pos xz) hK),
refine le_trans _ (le_of_lt $ hf₂ _ n0 _ xS),
rwa [le_sub, inv_le ((nat.cast_pos.2 n0):((_:ℝ) < _)) xz] },
{ exact mk_le_of_forall_le ⟨1, λ n n1,
let ⟨x, xS, hx⟩ := hf₁ _ n1 in le_trans hx (h _ xS)⟩ },
intros ε ε0,
suffices : ∀ j k ≥ nat_ceil ε⁻¹, (f j / j - f k / k : ℚ) < ε,
{ refine ⟨_, λ j ij, abs_lt.2 ⟨_, this _ _ ij (le_refl _)⟩⟩,
rw [neg_lt, neg_sub], exact this _ _ (le_refl _) ij },
intros j k ij ik,
replace ij := le_trans (le_nat_ceil _) (nat.cast_le.2 ij),
replace ik := le_trans (le_nat_ceil _) (nat.cast_le.2 ik),
have j0 := nat.cast_pos.1 (lt_of_lt_of_le (inv_pos ε0) ij),
have k0 := nat.cast_pos.1 (lt_of_lt_of_le (inv_pos ε0) ik),
rcases hf₁ _ j0 with ⟨y, yS, hy⟩,
refine lt_of_lt_of_le ((@rat.cast_lt ℝ _ _ _).1 _)
((inv_le ε0 (nat.cast_pos.2 k0)).1 ik),
simpa using sub_lt_iff_lt_add'.2
(lt_of_le_of_lt hy $ sub_lt_iff_lt_add.1 $ hf₂ _ k0 _ yS)
end
noncomputable def Sup (S : set ℝ) : ℝ :=
if h : (∃ x, x ∈ S) ∧ (∃ x, ∀ y ∈ S, y ≤ x)
then classical.some (exists_sup S h.1 h.2) else 0
theorem Sup_le (S : set ℝ) (h₁ : ∃ x, x ∈ S) (h₂ : ∃ x, ∀ y ∈ S, y ≤ x)
{y} : Sup S ≤ y ↔ ∀ z ∈ S, z ≤ y :=
by simp [Sup, h₁, h₂]; exact
classical.some_spec (exists_sup S h₁ h₂) y
section
-- this proof times out without this
local attribute [instance, priority 1000] classical.prop_decidable
theorem lt_Sup (S : set ℝ) (h₁ : ∃ x, x ∈ S) (h₂ : ∃ x, ∀ y ∈ S, y ≤ x)
{y} : y < Sup S ↔ ∃ z ∈ S, y < z :=
by simpa [not_forall] using not_congr (@Sup_le S h₁ h₂ y)
end
theorem le_Sup (S : set ℝ) (h₂ : ∃ x, ∀ y ∈ S, y ≤ x) {x} (xS : x ∈ S) : x ≤ Sup S :=
(Sup_le S ⟨_, xS⟩ h₂).1 (le_refl _) _ xS
theorem Sup_le_ub (S : set ℝ) (h₁ : ∃ x, x ∈ S) {ub} (h₂ : ∀ y ∈ S, y ≤ ub) : Sup S ≤ ub :=
(Sup_le S h₁ ⟨_, h₂⟩).2 h₂
protected lemma is_lub_Sup {s : set ℝ} {a b : ℝ} (ha : a ∈ s) (hb : b ∈ upper_bounds s) :
is_lub s (Sup s) :=
⟨λ x xs, real.le_Sup s ⟨_, hb⟩ xs,
λ u h, real.Sup_le_ub _ ⟨_, ha⟩ h⟩
noncomputable def Inf (S : set ℝ) : ℝ := -Sup {x | -x ∈ S}
theorem le_Inf (S : set ℝ) (h₁ : ∃ x, x ∈ S) (h₂ : ∃ x, ∀ y ∈ S, x ≤ y)
{y} : y ≤ Inf S ↔ ∀ z ∈ S, y ≤ z :=
begin
refine le_neg.trans ((Sup_le _ _ _).trans _),
{ cases h₁ with x xS, exact ⟨-x, by simp [xS]⟩ },
{ cases h₂ with ub h, exact ⟨-ub, λ y hy, le_neg.1 $ h _ hy⟩ },
split; intros H z hz,
{ exact neg_le_neg_iff.1 (H _ $ by simp [hz]) },
{ exact le_neg.2 (H _ hz) }
end
section
-- this proof times out without this
local attribute [instance, priority 1000] classical.prop_decidable
theorem Inf_lt (S : set ℝ) (h₁ : ∃ x, x ∈ S) (h₂ : ∃ x, ∀ y ∈ S, x ≤ y)
{y} : Inf S < y ↔ ∃ z ∈ S, z < y :=
by simpa [not_forall] using not_congr (@le_Inf S h₁ h₂ y)
end
theorem Inf_le (S : set ℝ) (h₂ : ∃ x, ∀ y ∈ S, x ≤ y) {x} (xS : x ∈ S) : Inf S ≤ x :=
(le_Inf S ⟨_, xS⟩ h₂).1 (le_refl _) _ xS
theorem lb_le_Inf (S : set ℝ) (h₁ : ∃ x, x ∈ S) {lb} (h₂ : ∀ y ∈ S, lb ≤ y) : lb ≤ Inf S :=
(le_Inf S h₁ ⟨_, h₂⟩).2 h₂
open lattice
noncomputable instance lattice : lattice ℝ := by apply_instance
noncomputable instance : conditionally_complete_linear_order ℝ :=
{ Sup := real.Sup,
Inf := real.Inf,
le_cSup :=
assume (s : set ℝ) (a : ℝ) (_ : bdd_above s) (_ : a ∈ s),
show a ≤ Sup s,
from le_Sup s ‹bdd_above s› ‹a ∈ s›,
cSup_le :=
assume (s : set ℝ) (a : ℝ) (_ : s ≠ ∅) (H : ∀b∈s, b ≤ a),
show Sup s ≤ a,
from Sup_le_ub s (set.exists_mem_of_ne_empty ‹s ≠ ∅›) H,
cInf_le :=
assume (s : set ℝ) (a : ℝ) (_ : bdd_below s) (_ : a ∈ s),
show Inf s ≤ a,
from Inf_le s ‹bdd_below s› ‹a ∈ s›,
le_cInf :=
assume (s : set ℝ) (a : ℝ) (_ : s ≠ ∅) (H : ∀b∈s, a ≤ b),
show a ≤ Inf s,
from lb_le_Inf s (set.exists_mem_of_ne_empty ‹s ≠ ∅›) H,
decidable_le := classical.dec_rel _,
..real.linear_order, ..real.lattice}
theorem Sup_empty : lattice.Sup (∅ : set ℝ) = 0 := dif_neg $ by simp
theorem Sup_of_not_bdd_above {s : set ℝ} (hs : ¬ bdd_above s) : lattice.Sup s = 0 :=
dif_neg $ assume h, hs h.2
theorem Sup_univ : real.Sup set.univ = 0 :=
real.Sup_of_not_bdd_above $ λ h,
Exists.dcases_on h $ λ x h', not_le_of_lt (lt_add_one _) $ h' (x + 1) $ set.mem_univ _
theorem Inf_empty : lattice.Inf (∅ : set ℝ) = 0 :=
show Inf ∅ = 0, by simp [Inf]; exact Sup_empty
theorem Inf_of_not_bdd_below {s : set ℝ} (hs : ¬ bdd_below s) : lattice.Inf s = 0 :=
have bdd_above {x | -x ∈ s} → bdd_below s, from
assume ⟨b, hb⟩, ⟨-b, assume x hxs, neg_le.2 $ hb _ $ by simp [hxs]⟩,
have ¬ bdd_above {x | -x ∈ s}, from mt this hs,
neg_eq_zero.2 $ Sup_of_not_bdd_above $ this
theorem cau_seq_converges (f : cau_seq ℝ abs) : ∃ x, f ≈ const abs x :=
begin
let S := {x : ℝ | const abs x < f},
have lb : ∃ x, x ∈ S := exists_lt f,
have ub' : ∀ x, f < const abs x → ∀ y ∈ S, y ≤ x :=
λ x h y yS, le_of_lt $ const_lt.1 $ cau_seq.lt_trans yS h,
have ub : ∃ x, ∀ y ∈ S, y ≤ x := (exists_gt f).imp ub',
refine ⟨Sup S,
((lt_total _ _).resolve_left (λ h, _)).resolve_right (λ h, _)⟩,
{ rcases h with ⟨ε, ε0, i, ih⟩,
refine not_lt_of_le (Sup_le_ub S lb (ub' _ _))
((sub_lt_self_iff _).2 (half_pos ε0)),
refine ⟨_, half_pos ε0, i, λ j ij, _⟩,
rw [sub_apply, const_apply, sub_right_comm,
le_sub_iff_add_le, add_halves],
exact ih _ ij },
{ rcases h with ⟨ε, ε0, i, ih⟩,
refine not_lt_of_le (le_Sup S ub _)
((lt_add_iff_pos_left _).2 (half_pos ε0)),
refine ⟨_, half_pos ε0, i, λ j ij, _⟩,
rw [sub_apply, const_apply, add_comm, ← sub_sub,
le_sub_iff_add_le, add_halves],
exact ih _ ij }
end
noncomputable instance : cau_seq.is_complete ℝ abs := ⟨cau_seq_converges⟩
theorem sqrt_exists : ∀ {x : ℝ}, 0 ≤ x → ∃ y, 0 ≤ y ∧ y * y = x :=
suffices H : ∀ {x : ℝ}, 0 < x → x ≤ 1 → ∃ y, 0 < y ∧ y * y = x, begin
intros x x0, cases x0,
cases le_total x 1 with x1 x1,
{ rcases H x0 x1 with ⟨y, y0, hy⟩,
exact ⟨y, le_of_lt y0, hy⟩ },
{ have := (inv_le_inv x0 zero_lt_one).2 x1,
rw inv_one at this,
rcases H (inv_pos x0) this with ⟨y, y0, hy⟩,
refine ⟨y⁻¹, le_of_lt (inv_pos y0), _⟩, rw [← mul_inv', hy, inv_inv'] },
{ exact ⟨0, by simp [x0.symm]⟩ }
end,
λ x x0 x1, begin
let S := {y | 0 < y ∧ y * y ≤ x},
have lb : x ∈ S := ⟨x0, by simpa using (mul_le_mul_right x0).2 x1⟩,
have ub : ∀ y ∈ S, (y:ℝ) ≤ 1,
{ intros y yS, cases yS with y0 yx,
refine (mul_self_le_mul_self_iff (le_of_lt y0) zero_le_one).2 _,
simpa using le_trans yx x1 },
have S0 : 0 < Sup S := lt_of_lt_of_le x0 (le_Sup _ ⟨_, ub⟩ lb),
refine ⟨Sup S, S0, le_antisymm (not_lt.1 $ λ h, _) (not_lt.1 $ λ h, _)⟩,
{ rw [← div_lt_iff S0, lt_Sup S ⟨_, lb⟩ ⟨_, ub⟩] at h,
rcases h with ⟨y, ⟨y0, yx⟩, hy⟩,
rw [div_lt_iff S0, ← div_lt_iff' y0, lt_Sup S ⟨_, lb⟩ ⟨_, ub⟩] at hy,
rcases hy with ⟨z, ⟨z0, zx⟩, hz⟩,
rw [div_lt_iff y0] at hz,
exact not_lt_of_lt
((mul_lt_mul_right y0).1 (lt_of_le_of_lt yx hz))
((mul_lt_mul_left z0).1 (lt_of_le_of_lt zx hz)) },
{ let s := Sup S, let y := s + (x - s * s) / 3,
replace h : 0 < x - s * s := sub_pos.2 h,
have _30 := bit1_pos zero_le_one,
have : s < y := (lt_add_iff_pos_right _).2 (div_pos h _30),
refine not_le_of_lt this (le_Sup S ⟨_, ub⟩ ⟨lt_trans S0 this, _⟩),
rw [add_mul_self_eq, add_assoc, ← le_sub_iff_add_le', ← add_mul,
← le_div_iff (div_pos h _30), div_div_cancel (ne_of_gt h)],
apply add_le_add,
{ simpa using (mul_le_mul_left (@two_pos ℝ _)).2 (Sup_le_ub _ ⟨_, lb⟩ ub) },
{ rw [div_le_one_iff_le _30],
refine le_trans (sub_le_self _ (mul_self_nonneg _)) (le_trans x1 _),
exact (le_add_iff_nonneg_left _).2 (le_of_lt two_pos) } }
end
def sqrt_aux (f : cau_seq ℚ abs) : ℕ → ℚ
| 0 := rat.mk_nat (f 0).num.to_nat.sqrt (f 0).denom.sqrt
| (n + 1) := let s := sqrt_aux n in max 0 $ (s + f (n+1) / s) / 2
theorem sqrt_aux_nonneg (f : cau_seq ℚ abs) : ∀ i : ℕ, 0 ≤ sqrt_aux f i
| 0 := by rw [sqrt_aux, mk_nat_eq, mk_eq_div];
apply div_nonneg'; exact int.cast_nonneg.2 (int.of_nat_nonneg _)
| (n + 1) := le_max_left _ _
/- TODO(Mario): finish the proof
theorem sqrt_aux_converges (f : cau_seq ℚ abs) : ∃ h x, 0 ≤ x ∧ x * x = max 0 (mk f) ∧
mk ⟨sqrt_aux f, h⟩ = x :=
begin
rcases sqrt_exists (le_max_left 0 (mk f)) with ⟨x, x0, hx⟩,
suffices : ∃ h, mk ⟨sqrt_aux f, h⟩ = x,
{ exact this.imp (λ h e, ⟨x, x0, hx, e⟩) },
apply of_near,
suffices : ∃ δ > 0, ∀ i, abs (↑(sqrt_aux f i) - x) < δ / 2 ^ i,
{ rcases this with ⟨δ, δ0, hδ⟩,
intros,
}
end -/
noncomputable def sqrt (x : ℝ) : ℝ :=
classical.some (sqrt_exists (le_max_left 0 x))
/-quotient.lift_on x
(λ f, mk ⟨sqrt_aux f, (sqrt_aux_converges f).fst⟩)
(λ f g e, begin
rcases sqrt_aux_converges f with ⟨hf, x, x0, xf, xs⟩,
rcases sqrt_aux_converges g with ⟨hg, y, y0, yg, ys⟩,
refine xs.trans (eq.trans _ ys.symm),
rw [← @mul_self_inj_of_nonneg ℝ _ x y x0 y0, xf, yg],
congr' 1, exact quotient.sound e
end)-/
theorem sqrt_prop (x : ℝ) : 0 ≤ sqrt x ∧ sqrt x * sqrt x = max 0 x :=
classical.some_spec (sqrt_exists (le_max_left 0 x))
/-quotient.induction_on x $ λ f,
by rcases sqrt_aux_converges f with ⟨hf, _, x0, xf, rfl⟩; exact ⟨x0, xf⟩-/
theorem sqrt_eq_zero_of_nonpos (h : x ≤ 0) : sqrt x = 0 :=
eq_zero_of_mul_self_eq_zero $ (sqrt_prop x).2.trans $ max_eq_left h
theorem sqrt_nonneg (x : ℝ) : 0 ≤ sqrt x := (sqrt_prop x).1
@[simp] theorem mul_self_sqrt (h : 0 ≤ x) : sqrt x * sqrt x = x :=
(sqrt_prop x).2.trans (max_eq_right h)
@[simp] theorem sqrt_mul_self (h : 0 ≤ x) : sqrt (x * x) = x :=
(mul_self_inj_of_nonneg (sqrt_nonneg _) h).1 (mul_self_sqrt (mul_self_nonneg _))
theorem sqrt_eq_iff_mul_self_eq (hx : 0 ≤ x) (hy : 0 ≤ y) :
sqrt x = y ↔ y * y = x :=
⟨λ h, by rw [← h, mul_self_sqrt hx],
λ h, by rw [← h, sqrt_mul_self hy]⟩
@[simp] theorem sqr_sqrt (h : 0 ≤ x) : sqrt x ^ 2 = x :=
by rw [pow_two, mul_self_sqrt h]
@[simp] theorem sqrt_sqr (h : 0 ≤ x) : sqrt (x ^ 2) = x :=
by rw [pow_two, sqrt_mul_self h]
theorem sqrt_eq_iff_sqr_eq (hx : 0 ≤ x) (hy : 0 ≤ y) :
sqrt x = y ↔ y ^ 2 = x :=
by rw [pow_two, sqrt_eq_iff_mul_self_eq hx hy]
theorem sqrt_mul_self_eq_abs (x : ℝ) : sqrt (x * x) = abs x :=
(le_total 0 x).elim
(λ h, (sqrt_mul_self h).trans (abs_of_nonneg h).symm)
(λ h, by rw [← neg_mul_neg,
sqrt_mul_self (neg_nonneg.2 h), abs_of_nonpos h])
theorem sqrt_sqr_eq_abs (x : ℝ) : sqrt (x ^ 2) = abs x :=
by rw [pow_two, sqrt_mul_self_eq_abs]
@[simp] theorem sqrt_zero : sqrt 0 = 0 :=
by simpa using sqrt_mul_self (le_refl _)
@[simp] theorem sqrt_one : sqrt 1 = 1 :=
by simpa using sqrt_mul_self zero_le_one
@[simp] theorem sqrt_le (hx : 0 ≤ x) (hy : 0 ≤ y) : sqrt x ≤ sqrt y ↔ x ≤ y :=
by rw [mul_self_le_mul_self_iff (sqrt_nonneg _) (sqrt_nonneg _),
mul_self_sqrt hx, mul_self_sqrt hy]
@[simp] theorem sqrt_lt (hx : 0 ≤ x) (hy : 0 ≤ y) : sqrt x < sqrt y ↔ x < y :=
lt_iff_lt_of_le_iff_le (sqrt_le hy hx)
lemma sqrt_le_sqrt (h : x ≤ y) : sqrt x ≤ sqrt y :=
begin
rw [mul_self_le_mul_self_iff (sqrt_nonneg _) (sqrt_nonneg _), (sqrt_prop _).2, (sqrt_prop _).2],
exact max_le_max (le_refl _) h
end
lemma sqrt_le_left (hy : 0 ≤ y) : sqrt x ≤ y ↔ x ≤ y ^ 2 :=
begin
rw [mul_self_le_mul_self_iff (sqrt_nonneg _) hy, pow_two],
cases le_total 0 x with hx hx,
{ rw [mul_self_sqrt hx] },
{ have h1 : 0 ≤ y * y := mul_nonneg hy hy,
have h2 : x ≤ y * y := le_trans hx h1,
simp [sqrt_eq_zero_of_nonpos, hx, h1, h2] }
end
/- note: if you want to conclude `x ≤ sqrt y`, then use `le_sqrt_of_sqr_le`.
if you have `x > 0`, consider using `le_sqrt'` -/
lemma le_sqrt (hx : 0 ≤ x) (hy : 0 ≤ y) : x ≤ sqrt y ↔ x ^ 2 ≤ y :=
by rw [mul_self_le_mul_self_iff hx (sqrt_nonneg _), pow_two, mul_self_sqrt hy]
lemma le_sqrt' (hx : 0 < x) : x ≤ sqrt y ↔ x ^ 2 ≤ y :=
begin
rw [mul_self_le_mul_self_iff (le_of_lt hx) (sqrt_nonneg _), pow_two],
cases le_total 0 y with hy hy,
{ rw [mul_self_sqrt hy] },
{ have h1 : 0 < x * x := mul_pos hx hx,
have h2 : ¬x * x ≤ y := not_le_of_lt (lt_of_le_of_lt hy h1),
simp [sqrt_eq_zero_of_nonpos, hy, h1, h2] }
end
lemma le_sqrt_of_sqr_le (h : x ^ 2 ≤ y) : x ≤ sqrt y :=
begin
cases lt_or_ge 0 x with hx hx,
{ rwa [le_sqrt' hx] },
{ exact le_trans hx (sqrt_nonneg y) }
end
@[simp] theorem sqrt_inj (hx : 0 ≤ x) (hy : 0 ≤ y) : sqrt x = sqrt y ↔ x = y :=
by simp [le_antisymm_iff, hx, hy]
@[simp] theorem sqrt_eq_zero (h : 0 ≤ x) : sqrt x = 0 ↔ x = 0 :=
by simpa using sqrt_inj h (le_refl _)
theorem sqrt_eq_zero' : sqrt x = 0 ↔ x ≤ 0 :=
(le_total x 0).elim
(λ h, by simp [h, sqrt_eq_zero_of_nonpos])
(λ h, by simp [h]; simp [le_antisymm_iff, h])
@[simp] theorem sqrt_pos : 0 < sqrt x ↔ 0 < x :=
lt_iff_lt_of_le_iff_le (iff.trans
(by simp [le_antisymm_iff, sqrt_nonneg]) sqrt_eq_zero')
@[simp] theorem sqrt_mul' (x) {y : ℝ} (hy : 0 ≤ y) : sqrt (x * y) = sqrt x * sqrt y :=
begin
cases le_total 0 x with hx hx,
{ refine (mul_self_inj_of_nonneg _ (mul_nonneg _ _)).1 _; try {apply sqrt_nonneg},
rw [mul_self_sqrt (mul_nonneg hx hy), mul_assoc,
mul_left_comm (sqrt y), mul_self_sqrt hy, ← mul_assoc, mul_self_sqrt hx] },
{ rw [sqrt_eq_zero'.2 (mul_nonpos_of_nonpos_of_nonneg hx hy),
sqrt_eq_zero'.2 hx, zero_mul] }
end
@[simp] theorem sqrt_mul (hx : 0 ≤ x) (y : ℝ) : sqrt (x * y) = sqrt x * sqrt y :=
by rw [mul_comm, sqrt_mul' _ hx, mul_comm]
@[simp] theorem sqrt_inv (x : ℝ) : sqrt x⁻¹ = (sqrt x)⁻¹ :=
(le_or_lt x 0).elim
(λ h, by simp [sqrt_eq_zero'.2, inv_nonpos, h])
(λ h, by rw [
← mul_self_inj_of_nonneg (sqrt_nonneg _) (le_of_lt $ inv_pos $ sqrt_pos.2 h),
mul_self_sqrt (le_of_lt $ inv_pos h), ← mul_inv', mul_self_sqrt (le_of_lt h)])
@[simp] theorem sqrt_div (hx : 0 ≤ x) (y : ℝ) : sqrt (x / y) = sqrt x / sqrt y :=
by rw [division_def, sqrt_mul hx, sqrt_inv]; refl
attribute [irreducible] real.le
end real
|
bbd53a016628054351b9b226d0021b870a3dcd76 | 618003631150032a5676f229d13a079ac875ff77 | /src/tactic/rcases.lean | 1ce55f8e813946dc6b5af52855b7752dce422381 | [
"Apache-2.0"
] | permissive | awainverse/mathlib | 939b68c8486df66cfda64d327ad3d9165248c777 | ea76bd8f3ca0a8bf0a166a06a475b10663dec44a | refs/heads/master | 1,659,592,962,036 | 1,590,987,592,000 | 1,590,987,592,000 | 268,436,019 | 1 | 0 | Apache-2.0 | 1,590,990,500,000 | 1,590,990,500,000 | null | UTF-8 | Lean | false | false | 20,250 | lean | /-
Copyright (c) 2017 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
-/
import data.dlist
import tactic.core
open lean lean.parser
namespace tactic
/-
These synonyms for `list` are used to clarify the meanings of the many
usages of lists in this module.
- `listΣ` is used where a list represents a disjunction, such as the
list of possible constructors of an inductive type.
- `listΠ` is used where a list represents a conjunction, such as the
list of arguments of an individual constructor.
These are merely type synonyms, and so are not checked for consistency
by the compiler.
The `def`/`local notation` combination makes Lean retain these
annotations in reported types.
-/
@[reducible] def list_Sigma := list
@[reducible] def list_Pi := list
local notation `listΣ` := list_Sigma
local notation `listΠ` := list_Pi
@[reducible] meta def goals := list expr
meta inductive rcases_patt : Type
| one : name → rcases_patt
| many : listΣ (listΠ rcases_patt) → rcases_patt
meta instance rcases_patt.inhabited : inhabited rcases_patt :=
⟨rcases_patt.one `_⟩
meta def rcases_patt.name : rcases_patt → name
| (rcases_patt.one n) := n
| _ := `_
meta instance rcases_patt.has_reflect : has_reflect rcases_patt
| (rcases_patt.one n) := `(_)
| (rcases_patt.many l) := `(λ l, rcases_patt.many l).subst $
by haveI := rcases_patt.has_reflect; exact list.reflect l
/--
The parser/printer uses an "inverted" meaning for the `many` constructor:
rather than representing a sum of products, here it represents a
product of sums. We fix this by applying `invert`, defined below, to
the result.
-/
meta inductive rcases_patt_inverted : Type
| one : name → rcases_patt_inverted
| many : listΠ (listΣ rcases_patt_inverted) → rcases_patt_inverted
meta instance rcases_patt_inverted.inhabited : inhabited rcases_patt_inverted :=
⟨rcases_patt_inverted.one `_⟩
meta instance rcases_patt_inverted.has_reflect : has_reflect rcases_patt_inverted
| (rcases_patt_inverted.one n) := `(_)
| (rcases_patt_inverted.many l) := `(λ l, rcases_patt_inverted.many l).subst $
by haveI := rcases_patt_inverted.has_reflect; exact list.reflect l
meta mutual def rcases_patt_inverted.invert, rcases_patt_inverted.invert_list
with rcases_patt_inverted.invert : listΣ rcases_patt_inverted → rcases_patt
| [rcases_patt_inverted.one n] := rcases_patt.one n
| l := rcases_patt.many (rcases_patt_inverted.invert_list l)
with rcases_patt_inverted.invert_list : listΣ rcases_patt_inverted → listΣ (listΠ rcases_patt)
| l := l.map $ λ p,
match p with
| rcases_patt_inverted.one n := [rcases_patt.one n]
| rcases_patt_inverted.many l := rcases_patt_inverted.invert <$> l
end
meta mutual def rcases_patt.invert, rcases_patt.invert_many, rcases_patt.invert_list, rcases_patt.invert'
with rcases_patt.invert : rcases_patt → listΣ rcases_patt_inverted
| (rcases_patt.one n) := [rcases_patt_inverted.one n]
| (rcases_patt.many ls) := rcases_patt.invert_many ls
with rcases_patt.invert_many : listΣ (listΠ rcases_patt) → listΣ rcases_patt_inverted
| [] := []
| [[rcases_patt.many ls@(_::_::_)]] := rcases_patt.invert_many ls
| (l::ls) := rcases_patt.invert' l :: rcases_patt.invert_many ls
with rcases_patt.invert_list : listΠ rcases_patt → listΠ (listΣ rcases_patt_inverted)
| [] := []
| [rcases_patt.many [l@(_::_::_)]] := rcases_patt.invert_list l
| (p::l) := rcases_patt.invert p :: rcases_patt.invert_list l
with rcases_patt.invert' : listΠ rcases_patt → rcases_patt_inverted
| [rcases_patt.one n] := rcases_patt_inverted.one n
| [] := rcases_patt_inverted.one `_
| ls := rcases_patt_inverted.many (rcases_patt.invert_list ls)
meta mutual def rcases_patt_inverted.format, rcases_patt_inverted.format_list
with rcases_patt_inverted.format : rcases_patt_inverted → format
| (rcases_patt_inverted.one n) := to_fmt n
| (rcases_patt_inverted.many []) := "⟨⟩"
| (rcases_patt_inverted.many ls) := "⟨" ++ format.group (format.nest 1 $
format.join $ list.intersperse ("," ++ format.line) $
ls.map (format.group ∘ rcases_patt_inverted.format_list)) ++ "⟩"
with rcases_patt_inverted.format_list : listΣ rcases_patt_inverted → opt_param bool ff → format
| [] br := "⟨⟩"
| [p] br := rcases_patt_inverted.format p
| (p::l) br :=
let fmt := rcases_patt_inverted.format p ++ " |" ++ format.space ++
rcases_patt_inverted.format_list l in
if br then format.bracket "(" ")" fmt else fmt
meta instance rcases_patt_inverted.has_to_format :
has_to_format rcases_patt_inverted := ⟨rcases_patt_inverted.format⟩
meta def rcases_patt.format (p : rcases_patt) (br := ff) : format :=
rcases_patt_inverted.format_list p.invert br
meta instance rcases_patt.has_to_format : has_to_format rcases_patt := ⟨rcases_patt.format⟩
/--
Takes the number of fields of a single constructor and patterns to
match its fields against (not necessarily the same number). The
returned lists each contain one element per field of the
constructor. The `name` is the name which will be used in the
top-level `cases` tactic, and the `rcases_patt` is the pattern which
the field will be matched against by subsequent `cases` tactics.
-/
meta def rcases.process_constructor :
nat → listΠ rcases_patt → listΠ name × listΠ rcases_patt
| 0 ids := ([], [])
| 1 [] := ([`_], [default _])
| 1 [id] := ([id.name], [id])
-- The interesting case: we matched the last field against multiple
-- patterns, so split off the remaining patterns into a subsequent
-- match. This handles matching `α × β × γ` against `⟨a, b, c⟩`.
| 1 ids := ([`_], [rcases_patt.many [ids]])
| (n+1) ids :=
let (ns, ps) := rcases.process_constructor n ids.tail,
p := ids.head in
(p.name :: ns, p :: ps)
meta def rcases.process_constructors (params : nat) :
listΣ name → listΣ (listΠ rcases_patt) →
tactic (dlist name × listΣ (name × listΠ rcases_patt))
| [] ids := pure (dlist.empty, [])
| (c::cs) ids := do
n ← mk_const c >>= get_arity,
let (h, t) := (match cs, ids.tail with
-- We matched the last constructor against multiple patterns,
-- so split off the remaining constructors. This handles matching
-- `α ⊕ β ⊕ γ` against `a|b|c`.
| [], _::_ := ([rcases_patt.many ids], [])
| _, _ := (ids.head, ids.tail)
end : _),
let (ns, ps) := rcases.process_constructor (n - params) h,
(l, r) ← rcases.process_constructors cs t,
pure (dlist.of_list ns ++ l, (c, ps) :: r)
private def align {α β} (p : α → β → Prop) [∀ a b, decidable (p a b)] :
list α → list β → list (α × β)
| (a::as) (b::bs) :=
if p a b then (a, b) :: align as bs else align as (b::bs)
| _ _ := []
private meta def get_local_and_type (e : expr) : tactic (expr × expr) :=
(do t ← infer_type e, pure (t, e)) <|> (do
e ← get_local e.local_pp_name,
t ← infer_type e, pure (t, e))
meta mutual def rcases_core, rcases.continue
with rcases_core : listΣ (listΠ rcases_patt) → expr → tactic goals
| ids e := do
(t, e) ← get_local_and_type e,
t ← whnf t,
env ← get_env,
let I := t.get_app_fn.const_name,
(ids, r, l) ← (if I ≠ `quot
then do
when (¬env.is_inductive I) $
fail format!"rcases tactic failed: {e} : {I} is not an inductive datatype",
let params := env.inductive_num_params I,
let c := env.constructors_of I,
(ids, r) ← rcases.process_constructors params c ids,
l ← cases_core e ids.to_list,
return (ids, r, l)
else do
(ids, r) ← rcases.process_constructors 2 [`quot.mk] ids,
[(_, d)] ← induction e ids.to_list `quot.induction_on |
fail format!"quotient induction on {e} failed. Maybe goal is not in Prop?",
-- the result from `induction` is missing the information that the original constructor was
-- `quot.mk` so we fix this up:
return (ids, r, [(`quot.mk, d)])),
gs ← get_goals,
-- `cases_core` may not generate a new goal for every constructor,
-- as some constructors may be impossible for type reasons. (See its
-- documentation.) Match up the new goals with our remaining work
-- by constructor name.
list.join <$> (align (λ (a : name × _) (b : _ × name × _), a.1 = b.2.1) r (gs.zip l)).mmap
(λ⟨⟨_, ps⟩, g, _, hs, _⟩,
set_goals [g] >> rcases.continue (ps.zip hs))
with rcases.continue : listΠ (rcases_patt × expr) → tactic goals
| [] := get_goals
| ((rcases_patt.many ids, e) :: l) := do
gs ← rcases_core ids e,
list.join <$> gs.mmap (λ g, set_goals [g] >> rcases.continue l)
| ((rcases_patt.one `rfl, e) :: l) := do
(t, e) ← get_local_and_type e,
subst e,
rcases.continue l
-- If the pattern is any other name, we already bound the name in the
-- top-level `cases` tactic, so there is no more work to do for it.
| (_ :: l) := rcases.continue l
/-- `rcases h e pat` performs case distinction on `e` using `pat` to
name the arising new variables and assumptions. If `h` is `some` name,
a new assumption `h : e = pat` will relate the expression `e` with the
current pattern. -/
meta def rcases (h : option name) (p : pexpr) (ids : listΣ (listΠ rcases_patt)) : tactic unit :=
do e ← match h with
| some h :=
do x ← get_unused_name,
interactive.generalize h () (p, x),
get_local x
| none := i_to_expr p
end,
if e.is_local_constant then
focus1 (rcases_core ids e >>= set_goals)
else do
x ← mk_fresh_name,
n ← revert_kdependencies e semireducible,
(tactic.generalize e x)
<|>
(do t ← infer_type e,
tactic.assertv x t e,
get_local x >>= tactic.revert,
return ()),
h ← tactic.intro1,
focus1 (rcases_core ids h >>= set_goals)
meta def rintro (ids : listΠ rcases_patt) : tactic unit :=
do l ← ids.mmap (λ id, do
e ← intro id.name,
return (id, e)),
focus1 (rcases.continue l >>= set_goals)
def merge_list {α} (m : α → α → α) : list α → list α → list α
| [] l₂ := l₂
| l₁ [] := l₁
| (a :: l₁) (b :: l₂) := m a b :: merge_list l₁ l₂
meta def rcases_patt.merge : rcases_patt → rcases_patt → rcases_patt
| (rcases_patt.many ids₁) (rcases_patt.many ids₂) :=
rcases_patt.many (merge_list (merge_list rcases_patt.merge) ids₁ ids₂)
| (rcases_patt.one `rfl) (rcases_patt.many ids₂) :=
rcases_patt.many (merge_list (merge_list rcases_patt.merge) [[]] ids₂)
| (rcases_patt.many ids₁) (rcases_patt.one `rfl) :=
rcases_patt.many (merge_list (merge_list rcases_patt.merge) ids₁ [[]])
| (rcases_patt.one `rfl) (rcases_patt.one `rfl) := rcases_patt.one `rfl
| (rcases_patt.one `_) p := p
| p (rcases_patt.one `_) := p
| (rcases_patt.one n) _ := rcases_patt.one n
| _ (rcases_patt.one n) := rcases_patt.one n
meta mutual def rcases_hint_core, rcases_hint.process_constructors, rcases_hint.continue
with rcases_hint_core : ℕ → expr → tactic (rcases_patt × goals)
| depth e := do
(t, e) ← get_local_and_type e,
t ← whnf t,
env ← get_env,
some l ← try_core (guard (depth ≠ 0) >> cases_core e) |
prod.mk (rcases_patt.one e.local_pp_name) <$> get_goals,
let I := t.get_app_fn.const_name,
if I = ``eq then
prod.mk (rcases_patt.one `rfl) <$> get_goals
else do
let c := env.constructors_of I,
gs ← get_goals,
(ps, gs') ← rcases_hint.process_constructors (depth - 1) c (gs.zip l),
pure (rcases_patt.many ps, gs')
with rcases_hint.process_constructors : ℕ → listΣ name →
list (expr × name × listΠ expr × list (name × expr)) →
tactic (listΣ (listΠ rcases_patt) × goals)
| depth [] _ := pure ([], [])
| depth cs [] := pure (cs.map (λ _, []), [])
| depth (c::cs) ((g, c', hs, _) :: l) :=
if c ≠ c' then do
(ps, gs) ← rcases_hint.process_constructors depth cs l,
pure ([] :: ps, gs)
else do
(p, gs) ← set_goals [g] >> rcases_hint.continue depth hs,
(ps, gs') ← rcases_hint.process_constructors depth cs l,
pure (p :: ps, gs ++ gs')
with rcases_hint.continue : ℕ → listΠ expr → tactic (listΠ rcases_patt × goals)
| depth [] := prod.mk [] <$> get_goals
| depth (e :: l) := do
(p, gs) ← rcases_hint_core depth e,
(ps, gs') ← gs.mfoldl (λ (r : listΠ rcases_patt × goals) g,
do (ps, gs') ← set_goals [g] >> rcases_hint.continue depth l,
pure (merge_list rcases_patt.merge r.1 ps, r.2 ++ gs')) ([], []),
pure (p :: ps, gs')
meta def rcases_hint (p : pexpr) (depth : nat) : tactic rcases_patt :=
do e ← i_to_expr p,
if e.is_local_constant then
focus1 $ do (p, gs) ← rcases_hint_core depth e, set_goals gs, pure p
else do
x ← mk_fresh_name,
n ← revert_kdependencies e semireducible,
(tactic.generalize e x)
<|>
(do t ← infer_type e,
tactic.assertv x t e,
get_local x >>= tactic.revert,
pure ()),
h ← tactic.intro1,
focus1 $ do (p, gs) ← rcases_hint_core depth h, set_goals gs, pure p
meta def rintro_hint (depth : nat) : tactic (listΠ rcases_patt) :=
do l ← intros,
focus1 $ do
(p, gs) ← rcases_hint.continue depth l,
set_goals gs,
pure p
setup_tactic_parser
local notation `listΣ` := list_Sigma
local notation `listΠ` := list_Pi
meta def rcases_patt_parse_core
(rcases_patt_parse_list : parser (listΣ rcases_patt_inverted)) :
parser rcases_patt_inverted | x :=
((rcases_patt_inverted.one <$> ident_) <|>
(rcases_patt_inverted.many <$> brackets "⟨" "⟩"
(sep_by (tk ",") rcases_patt_parse_list))) x
meta def rcases_patt_parse_list : parser (listΣ rcases_patt_inverted) :=
with_desc "patt" $
list.cons <$> rcases_patt_parse_core rcases_patt_parse_list <*>
(tk "|" *> rcases_patt_parse_core rcases_patt_parse_list)*
meta def rcases_patt_parse : parser rcases_patt_inverted :=
with_desc "patt_list" $ rcases_patt_parse_core rcases_patt_parse_list
meta def rcases_parse_depth : parser nat :=
do o ← (tk ":" *> small_nat)?, pure $ o.get_or_else 5
precedence `?`:max
/-- syntax for a `rcases` pattern: `('?' expr (: n)?) | ((h :)? expr (with patt_list)?)` -/
meta def rcases_parse : parser (pexpr × ((option name × listΣ (listΠ rcases_patt)) ⊕ nat)) :=
with_desc "('?' expr (: n)?) | ((h :)? expr (with patt_list)?)" $
do hint ← (tk "?")?,
p ← texpr,
match hint with
| none := do
(h,p) ← (do { expr.local_const h _ _ _ ← pure p, tk ":", prod.mk (some h) <$> texpr } <|> pure (none,p)),
ids ← (tk "with" *> rcases_patt_parse_list)?,
pure (p, sum.inl (h, rcases_patt_inverted.invert_list (ids.get_or_else [default _])))
| some _ := do depth ← rcases_parse_depth, pure (p, sum.inr depth)
end
meta def rintro_parse : parser (listΠ rcases_patt ⊕ nat) :=
with_desc "('?' (: n)?) | patt_list" $
(tk "?" >> sum.inr <$> rcases_parse_depth) <|>
sum.inl <$> (rcases_patt_inverted.invert <$>
(brackets "(" ")" rcases_patt_parse_list <|>
(λ x, [x]) <$> rcases_patt_parse))*
meta def ext_patt := listΠ rcases_patt
meta def ext_parse : parser ext_patt :=
(rcases_patt_inverted.invert <$>
(brackets "(" ")" rcases_patt_parse_list <|>
(λ x, [x]) <$> rcases_patt_parse))*
namespace interactive
open interactive interactive.types expr
/--
The `rcases` tactic is the same as `cases`, but with more flexibility in the
`with` pattern syntax to allow for recursive case splitting. The pattern syntax
uses the following recursive grammar:
```lean
patt ::= (patt_list "|")* patt_list
patt_list ::= id | "rfl" | "_" | "⟨" (patt ",")* patt "⟩"
```
A pattern like `⟨a, b, c⟩ | ⟨d, e⟩` will do a split over the inductive datatype,
naming the first three parameters of the first constructor as `a,b,c` and the
first two of the second constructor `d,e`. If the list is not as long as the
number of arguments to the constructor or the number of constructors, the
remaining variables will be automatically named. If there are nested brackets
such as `⟨⟨a⟩, b | c⟩ | d` then these will cause more case splits as necessary.
If there are too many arguments, such as `⟨a, b, c⟩` for splitting on
`∃ x, ∃ y, p x`, then it will be treated as `⟨a, ⟨b, c⟩⟩`, splitting the last
parameter as necessary.
If `rcases` results in an expression of the form `x = a`, then using `rfl`
in the pattern will have the same effect as writing `h` and then
following the `rcases` with a `subst h`.
`rcases` also has special support for quotient types: quotient induction into Prop works like
matching on the constructor `quot.mk`.
`rcases h : e with PAT` will do the same as `rcases e with PAT` with the exception that an assumption
`h : e = PAT` will be added to the context.
`rcases? e` will perform case splits on `e` in the same way as `rcases e`,
but rather than accepting a pattern, it does a maximal cases and prints the
pattern that would produce this case splitting. The default maximum depth is 5,
but this can be modified with `rcases? e : n`.
-/
meta def rcases : parse rcases_parse → tactic unit
| (p, sum.inl (h, ids)) := tactic.rcases h p ids
| (p, sum.inr depth) := do
patt ← tactic.rcases_hint p depth,
pe ← pp p,
trace $ ↑"Try this: rcases " ++ pe ++ " with " ++ to_fmt patt
add_tactic_doc
{ name := "rcases",
category := doc_category.tactic,
decl_names := [`tactic.interactive.rcases],
tags := ["induction"] }
/--
The `rintro` tactic is a combination of the `intros` tactic with `rcases` to
allow for destructuring patterns while introducing variables. See `rcases` for
a description of supported patterns. For example, `rintro (a | ⟨b, c⟩) ⟨d, e⟩`
will introduce two variables, and then do case splits on both of them producing
two subgoals, one with variables `a d e` and the other with `b c d e`.
`rintro?` will introduce and case split on variables in the same way as
`rintro`, but will also print the `rintro` invocation that would have the same
result. Like `rcases?`, `rintro? : n` allows for modifying the
depth of splitting; the default is 5.
`rintros` is an alias for `rintro`.
-/
meta def rintro : parse rintro_parse → tactic unit
| (sum.inl []) := intros []
| (sum.inl l) := tactic.rintro l
| (sum.inr depth) := do
ps ← tactic.rintro_hint depth,
trace $ ↑"Try this: rintro" ++ format.join (ps.map $ λ p,
format.space ++ format.group (p.format tt))
/-- Alias for `rintro`. -/
meta def rintros := rintro
add_tactic_doc
{ name := "rintro",
category := doc_category.tactic,
decl_names := [`tactic.interactive.rintro, `tactic.interactive.rintros],
tags := ["induction"],
inherit_description_from := `tactic.interactive.rintro }
setup_tactic_parser
meta def obtain_parse :
parser (option (listΣ rcases_patt_inverted) × (option pexpr) × (option pexpr)) :=
with_desc "patt_list? (: expr)? (:= expr)?" $
do pat ← rcases_patt_parse_list?,
tp ← (tk ":" >> texpr)?,
val ← (tk ":=" >> texpr)?,
return (pat, tp, val)
/--
The `obtain` tactic is a combination of `have` and `rcases`.
```lean
obtain ⟨patt⟩ : type,
{ ... }
```
is equivalent to
```lean
have h : type,
{ ... },
rcases h with ⟨patt⟩
```
The syntax `obtain ⟨patt⟩ : type := proof` is also supported.
If `⟨patt⟩` is omitted, `rcases` will try to infer the pattern.
If `type` is omitted, `:= proof` is required.
-/
meta def obtain : interactive.parse obtain_parse → tactic unit
| (pat, tp, some val) :=
tactic.rcases none ``(%%val : %%(tp.get_or_else pexpr.mk_placeholder)) $
rcases_patt_inverted.invert_list (pat.get_or_else [default _])
| (pat, some tp, none) :=
do nm ← mk_fresh_name,
e ← to_expr tp >>= assert nm,
(g :: gs) ← get_goals,
set_goals gs,
tactic.rcases none ``(%%e) $ rcases_patt_inverted.invert_list (pat.get_or_else [default _]),
gs ← get_goals,
set_goals (g::gs)
| (pat, none, none) :=
fail $ "`obtain` requires either an expected type or a value.\n" ++
"usage: `obtain ⟨patt⟩? : type (:= val)?` or `obtain ⟨patt⟩? (: type)? := val`"
add_tactic_doc
{ name := "obtain",
category := doc_category.tactic,
decl_names := [`tactic.interactive.obtain],
tags := ["induction"] }
end interactive
end tactic
|
34bfb1169c1deadc9313c0212f5870a415cea10b | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/tactic/equiv_rw.lean | 51b713e460f81b180154b844e9bcf2326426fc5a | [] | no_license | AurelienSaue/Mathlib4_auto | f538cfd0980f65a6361eadea39e6fc639e9dae14 | 590df64109b08190abe22358fabc3eae000943f2 | refs/heads/master | 1,683,906,849,776 | 1,622,564,669,000 | 1,622,564,669,000 | 371,723,747 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 5,147 | lean | /-
Copyright (c) 2019 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.tactic.simp_result
import Mathlib.tactic.clear
import Mathlib.control.equiv_functor.instances
import Mathlib.PostPort
namespace Mathlib
/-!
# The `equiv_rw` tactic transports goals or hypotheses along equivalences.
The basic syntax is `equiv_rw e`, where `e : α ≃ β` is an equivalence.
This will try to replace occurrences of `α` in the goal with `β`, for example
transforming
* `⊢ α` to `⊢ β`,
* `⊢ option α` to `⊢ option β`
* `⊢ {a // P}` to `{b // P (⇑(equiv.symm e) b)}`
The tactic can also be used to rewrite hypotheses, using the syntax `equiv_rw e at h`.
## Implementation details
The main internal function is `equiv_rw_type e t`,
which attempts to turn an expression `e : α ≃ β` into a new equivalence with left hand side `t`.
As an example, with `t = option α`, it will generate `functor.map_equiv option e`.
This is achieved by generating a new synthetic goal `%%t ≃ _`,
and calling `solve_by_elim` with an appropriate set of congruence lemmas.
To avoid having to specify the relevant congruence lemmas by hand,
we mostly rely on `equiv_functor.map_equiv` and `bifunctor.map_equiv`
along with some structural congruence lemmas such as
* `equiv.arrow_congr'`,
* `equiv.subtype_equiv_of_subtype'`,
* `equiv.sigma_congr_left'`, and
* `equiv.Pi_congr_left'`.
The main `equiv_rw` function, when operating on the goal, simply generates a new equivalence `e'`
with left hand side matching the target, and calls `apply e'.inv_fun`.
When operating on a hypothesis `x : α`, we introduce a new fact `h : x = e.symm (e x)`,
revert this, and then attempt to `generalize`, replacing all occurrences of `e x` with a new constant `y`,
before `intro`ing and `subst`ing `h`, and renaming `y` back to `x`.
## Future improvements
In a future PR I anticipate that `derive equiv_functor` should work on many examples,
(internally using `transport`, which is in turn based on `equiv_rw`)
and we can incrementally bootstrap the strength of `equiv_rw`.
An ambitious project might be to add `equiv_rw!`,
a tactic which, when failing to find appropriate `equiv_functor` instances,
attempts to `derive` them on the spot.
For now `equiv_rw` is entirely based on `equiv`,
but the framework can readily be generalised to also work with other types of equivalences,
for example specific notations such as ring equivalence (`≃+*`),
or general categorical isomorphisms (`≅`).
This will allow us to transport across more general types of equivalences,
but this will wait for another subsequent PR.
-/
namespace tactic
/-- A list of lemmas used for constructing congruence equivalences. -/
-- Although this looks 'hard-coded', in fact the lemma `equiv_functor.map_equiv`
-- allows us to extend `equiv_rw` simply by constructing new instance so `equiv_functor`.
-- TODO: We should also use `category_theory.functorial` and `category_theory.hygienic` instances.
-- (example goal: we could rewrite along an isomorphism of rings (either as `R ≅ S` or `R ≃+* S`)
-- and turn an `x : mv_polynomial σ R` into an `x : mv_polynomial σ S`.).
/--
Configuration structure for `equiv_rw`.
* `max_depth` bounds the search depth for equivalences to rewrite along.
The default value is 10.
(e.g., if you're rewriting along `e : α ≃ β`, and `max_depth := 2`,
you can rewrite `option (option α))` but not `option (option (option α))`.
-/
/--
Implementation of `equiv_rw_type`, using `solve_by_elim`.
Expects a goal of the form `t ≃ _`,
and tries to solve it using `eq : α ≃ β` and congruence lemmas.
-/
/--
`equiv_rw_type e t` rewrites the type `t` using the equivalence `e : α ≃ β`,
returning a new equivalence `t ≃ t'`.
-/
/--
Attempt to replace the hypothesis with name `x`
by transporting it along the equivalence in `e : α ≃ β`.
-/
-- We call `dsimp_result` to perform the beta redex introduced by `revert`
/-- Rewrite the goal using an equiv `e`. -/
end tactic
namespace tactic.interactive
/--
`equiv_rw e at h`, where `h : α` is a hypothesis, and `e : α ≃ β`,
will attempt to transport `h` along `e`, producing a new hypothesis `h : β`,
with all occurrences of `h` in other hypotheses and the goal replaced with `e.symm h`.
`equiv_rw e` will attempt to transport the goal along an equivalence `e : α ≃ β`.
In its minimal form it replaces the goal `⊢ α` with `⊢ β` by calling `apply e.inv_fun`.
`equiv_rw` will also try rewriting under (equiv_)functors, so can turn
a hypothesis `h : list α` into `h : list β` or
a goal `⊢ unique α` into `⊢ unique β`.
The maximum search depth for rewriting in subexpressions is controlled by
`equiv_rw e {max_depth := n}`.
-/
/--
Solve a goal of the form `t ≃ _`,
by constructing an equivalence from `e : α ≃ β`.
This is the same equivalence that `equiv_rw` would use to rewrite a term of type `t`.
A typical usage might be:
```
have e' : option α ≃ option β := by equiv_rw_type e
```
-/
|
7fe539b0d6e2a89630034fbfe2eb585da9af5cb8 | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/data/pi/interval.lean | 812b52ef971223f0598058758a5646e7dfdfdfd3 | [
"Apache-2.0"
] | permissive | leanprover-community/mathlib | 56a2cadd17ac88caf4ece0a775932fa26327ba0e | 442a83d738cb208d3600056c489be16900ba701d | refs/heads/master | 1,693,584,102,358 | 1,693,471,902,000 | 1,693,471,902,000 | 97,922,418 | 1,595 | 352 | Apache-2.0 | 1,694,693,445,000 | 1,500,624,130,000 | Lean | UTF-8 | Lean | false | false | 2,902 | lean | /-
Copyright (c) 2021 Yaël Dillies. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies
-/
import data.finset.locally_finite
import data.fintype.big_operators
/-!
# Intervals in a pi type
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
This file shows that (dependent) functions to locally finite orders equipped with the pointwise
order are locally finite and calculates the cardinality of their intervals.
-/
open finset fintype
open_locale big_operators
variables {ι : Type*} {α : ι → Type*} [fintype ι] [decidable_eq ι] [Π i, decidable_eq (α i)]
namespace pi
section partial_order
variables [Π i, partial_order (α i)]
section locally_finite_order
variables [Π i, locally_finite_order (α i)]
instance : locally_finite_order (Π i, α i) :=
locally_finite_order.of_Icc _
(λ a b, pi_finset $ λ i, Icc (a i) (b i))
(λ a b x, by simp_rw [mem_pi_finset, mem_Icc, le_def, forall_and_distrib])
variables (a b : Π i, α i)
lemma Icc_eq : Icc a b = pi_finset (λ i, Icc (a i) (b i)) := rfl
lemma card_Icc : (Icc a b).card = ∏ i, (Icc (a i) (b i)).card := card_pi_finset _
lemma card_Ico : (Ico a b).card = ∏ i, (Icc (a i) (b i)).card - 1 :=
by rw [card_Ico_eq_card_Icc_sub_one, card_Icc]
lemma card_Ioc : (Ioc a b).card = ∏ i, (Icc (a i) (b i)).card - 1 :=
by rw [card_Ioc_eq_card_Icc_sub_one, card_Icc]
lemma card_Ioo : (Ioo a b).card = ∏ i, (Icc (a i) (b i)).card - 2 :=
by rw [card_Ioo_eq_card_Icc_sub_two, card_Icc]
end locally_finite_order
section locally_finite_order_bot
variables [Π i, locally_finite_order_bot (α i)] (b : Π i, α i)
instance : locally_finite_order_bot (Π i, α i) :=
locally_finite_order_top.of_Iic _
(λ b, pi_finset $ λ i, Iic (b i))
(λ b x, by simp_rw [mem_pi_finset, mem_Iic, le_def])
lemma card_Iic : (Iic b).card = ∏ i, (Iic (b i)).card := card_pi_finset _
lemma card_Iio : (Iio b).card = ∏ i, (Iic (b i)).card - 1 :=
by rw [card_Iio_eq_card_Iic_sub_one, card_Iic]
end locally_finite_order_bot
section locally_finite_order_top
variables [Π i, locally_finite_order_top (α i)] (a : Π i, α i)
instance : locally_finite_order_top (Π i, α i) :=
locally_finite_order_top.of_Ici _
(λ a, pi_finset $ λ i, Ici (a i))
(λ a x, by simp_rw [mem_pi_finset, mem_Ici, le_def])
lemma card_Ici : (Ici a).card = ∏ i, (Ici (a i)).card := card_pi_finset _
lemma card_Ioi : (Ioi a).card = ∏ i, (Ici (a i)).card - 1 :=
by rw [card_Ioi_eq_card_Ici_sub_one, card_Ici]
end locally_finite_order_top
end partial_order
section lattice
variables [Π i, lattice (α i)] [Π i, locally_finite_order (α i)] (a b : Π i, α i)
lemma uIcc_eq : uIcc a b = pi_finset (λ i, uIcc (a i) (b i)) := rfl
lemma card_uIcc : (uIcc a b).card = ∏ i, (uIcc (a i) (b i)).card := card_Icc _ _
end lattice
end pi
|
ba2f122f731150165f5b8ff924f6f03f6066c32a | a721fe7446524f18ba361625fc01033d9c8b7a78 | /src/principia/real/le.lean | 7ea17752811bae3ddb23c63b97e283a90483182c | [] | no_license | Sterrs/leaning | 8fd80d1f0a6117a220bb2e57ece639b9a63deadc | 3901cc953694b33adda86cb88ca30ba99594db31 | refs/heads/master | 1,627,023,822,744 | 1,616,515,221,000 | 1,616,515,221,000 | 245,512,190 | 2 | 0 | null | 1,616,429,050,000 | 1,583,527,118,000 | Lean | UTF-8 | Lean | false | false | 10,950 | lean | import .mul
noncomputable theory
namespace hidden
open myring
open ordered_myring
open integral_domain
open ordered_integral_domain
open myfield
open ordered_myfield
namespace cau_seq
def positive : cau_seq → Prop :=
λ f : cau_seq, ∃ ε : myrat,
0 < ε ∧ (∃ N : mynat, ∀ n, N ≤ n → ε < f.val n)
def positive_well_defined (f g : cau_seq) : f ≈ g → positive f = positive g :=
begin
assume hequiv,
apply propext,
rw setoid_equiv at hequiv,
dsimp [equivalent] at hequiv,
dsimp [positive] at *,
split; assume h,
all_goals {
cases h with ε h,
cases h with hε h,
cases h with N hN,
have hhalf_ε₁ := hequiv (ε / 2),
have hhalf_ε := hhalf_ε₁ (half_pos hε),
clear hhalf_ε₁,
cases hhalf_ε with M hM,
existsi (ε / 2),
split,
from half_pos hε,
existsi (mynat.max M N),
intro n,
assume hmax,
have hf := hN n (mynat.max_le_cancel_right hmax),
have hfg := hM n (mynat.max_le_cancel_left hmax),
clear hmax hM hN M N hequiv,
rw [lt_add_cancel_left (ε/2), half_plus_half myrat.two_nzero],
},
{
have := abs_lt_right _ _ hfg,
rw lt_add_cancel_right _ _ (g.val n) at this,
rw sub_def at this,
rw add_assoc at this,
rw neg_add at this,
rw add_zero at this,
transitivity (f.val n); assumption,
}, {
have := abs_lt_left _ _ hfg,
rw lt_add_cancel_right _ _ (-f.val n) at this,
rw sub_def at this,
rw add_comm (f.val n + _) at this,
rw ←add_assoc at this,
rw neg_add at this,
rw zero_add at this,
rw lt_neg_switch_iff at this,
rw [neg_distr, neg_neg, neg_neg, neg_neg] at this,
transitivity (g.val n); assumption,
},
end
theorem zero_npos : ¬positive 0 :=
begin
assume h,
cases h with ε hε,
cases hε with hε hN,
cases hN with N hN,
suffices : (0 : myrat) < 0,
from lt_nrefl 0 this,
transitivity ε,
assumption,
have h₁ := hN N mynat.le_refl,
assumption,
end
end cau_seq
namespace real
def positive : real → Prop :=
quotient.lift cau_seq.positive cau_seq.positive_well_defined
private theorem pos_cls {x : real} {f : cau_seq} :
x = ⟦f⟧ → (positive x ↔ ∃ ε : myrat, 0 < ε ∧ (∃ N : mynat, ∀ n, N ≤ n → ε < f.val n)) :=
begin
assume hxf,
subst hxf,
refl,
end
-- Because it's annoying to reorder manually
universe u
private lemma exists_rep {α : Sort u} [s : setoid α] (q : quotient s) : ∃ a : α, q = ⟦a⟧ :=
begin
cases quotient.exists_rep q with a ha,
existsi a,
symmetry,
assumption,
end
private theorem pos_add_closed (x y : real) : positive x → positive y → positive (x + y) :=
begin
assume hx hy,
cases exists_rep x with a ha,
cases exists_rep y with b hb,
subst ha, subst hb,
change positive ⟦a + b⟧,
rw pos_cls rfl,
rw pos_cls rfl at hx,
rw pos_cls rfl at hy,
cases hx with ε hx,
cases hx with hε hx,
cases hx with N hN,
cases hy with δ hy,
cases hy with hδ hy,
cases hy with M hM,
existsi ε + δ,
split, {
rw ←zero_add (0 : myrat),
apply lt_comb; assumption,
}, {
existsi mynat.max M N,
intros n hn,
rw cau_seq.add_val,
apply lt_comb,
exact hN n (mynat.max_le_cancel_right hn),
exact hM n (mynat.max_le_cancel_left hn),
},
end
private theorem pos_mul_closed (x y : real) : positive x → positive y → positive (x * y) :=
begin
assume hx hy,
cases exists_rep x with a ha,
cases exists_rep y with b hb,
subst ha, subst hb,
change positive ⟦a * b⟧,
rw pos_cls rfl,
rw pos_cls rfl at hx,
rw pos_cls rfl at hy,
cases hx with ε hx,
cases hx with hε hx,
cases hx with N hN,
cases hy with δ hy,
cases hy with hδ hy,
cases hy with M hM,
existsi ε * δ,
split, {
apply pos_mul_pos; assumption,
}, {
existsi mynat.max M N,
intros n hn,
rw cau_seq.mul_val,
have hM₁ := hM n (mynat.max_le_cancel_left hn),
have hN₁ := hN n (mynat.max_le_cancel_right hn),
apply lt_mul_comb_nonneg,
any_goals { {apply lt_impl_le, assumption} <|> assumption, },
},
end
private theorem neg_pos_impl_nonpos (x : real) : positive (-x) → ¬positive x :=
begin
assume hx,
cases exists_rep x with a ha,
subst ha,
rw neg_eq_cls rfl at hx,
rw pos_cls rfl at hx,
rw pos_cls rfl,
rw not_exists,
have ha := a.property,
unfold is_cau_seq at ha,
intro ε,
rw not_and,
intro hε,
rw not_exists,
intros N,
rw not_forall,
cases hx with δ hx,
cases hx with hδ hx,
cases hx with M hM,
have := ha (ε + δ) _, {
cases this with K hK,
existsi N.max K,
rw not_imp,
split, {
apply mynat.max_le_left,
}, {
change ¬¬ _ ≤ ε,
rw not_not,
rw le_neg_switch_iff,
have h₁ := hK (N.max K) (M.max K) mynat.max_le_right mynat.max_le_right,
have h₂ := hM (M.max K) mynat.max_le_left,
clear ha hM hK,
rw cau_seq.neg_val at h₂,
apply lt_impl_le,
rw ←myring.add_zero (-ε),
rw ←neg_add δ,
rw ←myring.add_assoc,
rw ←myring.add_zero (-a.val _),
rw ←myring.add_neg (a.val (M.max K)),
rw ←myring.add_assoc,
apply lt_comb, {
rw ←neg_distr,
rw add_comm (-_),
rw ←sub_def,
apply abs_lt_left,
assumption,
}, {
assumption,
},
},
}, {
rw ←zero_add (0 : myrat),
apply lt_comb; assumption,
},
end
private theorem zero_nonpos : ¬positive (0 : real) :=
begin
by_contradiction h,
rw ←neg_zero at h,
have h₁ := neg_pos_impl_nonpos _ h,
rw neg_zero at h,
contradiction,
end
-- And partial converse
private theorem nzero_npos_impl_neg_pos {x : real} : x ≠ 0 → ¬positive x → positive (-x) :=
begin
intros hx0 hx,
cases exists_rep x with a ha,
subst ha,
rw neg_eq_cls rfl,
rw pos_cls rfl,
rw pos_cls rfl at hx,
rw not_exists at hx,
change ¬⟦a⟧ = (0 : real) at hx0,
rw [real_zero, coe_def, cau_seq.class_equiv] at hx0,
change ¬a ≈ _ at hx0,
cases cau_seq.nzero_impl_abs_eventually_bounded_below a hx0 with δ h,
cases h with N hN,
cases hN with hδ hN,
existsi δ,
split,
assumption,
have hδ2 := hx δ,
rw not_and at hδ2,
have hδ3 := hδ2 hδ,
rw not_exists at hδ3,
cases a.property δ hδ with M hM,
-- Here
have hδ4 := hδ3 (N.max M),
rw not_forall at hδ4,
cases hδ4 with n hn,
rw not_imp at hn,
cases hn with hNn hδ5,
clear hδ2 hδ3 hx,
-- And here
existsi (N.max M),
intros m hNm,
rw neg_val,
rw lt_neg_switch_iff,
rw neg_neg,
have hn := hN n (mynat.max_le_cancel_left hNn),
have hm := hN m (mynat.max_le_cancel_left hNm),
clear hN,
cases lt_abs_impl_lt_either _ _ hm, {
assumption,
}, {
exfalso,
clear hm,
cases lt_abs_impl_lt_either _ _ hn, {
have := hM n m (mynat.max_le_cancel_right hNn) (mynat.max_le_cancel_right hNm),
rw abs_sub_switch at this,
rw abs_lt_iff_lt_both at this,
apply lt_very_antisymmetric 0 (a.val n),
cases this with hneg hpos,
split, {
rw ←neg_add δ,
rw ←myring.add_zero (a.val n),
rw ←neg_add (a.val m),
rw ←myring.add_assoc,
apply lt_comb; assumption,
}, {
transitivity -δ,
assumption,
rw lt_neg_switch_iff,
rw neg_zero,
rw neg_neg,
assumption,
},
}, {
contradiction,
},
},
end
def le (x y : real) := ¬positive (x - y)
instance: has_le real := ⟨le⟩
local attribute [instance] classical.prop_decidable
variables x y z : real
private theorem le_add_right : x ≤ y → x + z ≤ y + z :=
begin
cases exists_rep x with a ha,
cases exists_rep y with b hb,
cases exists_rep z with c hc,
intros hxy,
subst ha, subst hb, subst hc,
change ¬positive (⟦a⟧ - ⟦b⟧) at hxy,
change ¬positive ((⟦a⟧ + ⟦c⟧) - (⟦b⟧ + ⟦c⟧)),
rw sub_def at *,
rw neg_distr,
rw add_assoc,
-- Super useful trick to avoid `conv`
-- Supply the *form* of the desired terms, let Lean figure out the _
rw add_comm _ (-_ + -_),
rw add_assoc (-_),
rw neg_add,
rw add_zero,
assumption,
end
private theorem zero_le_mul : 0 ≤ x → 0 ≤ y → 0 ≤ x * y :=
begin
intros hx hy,
by_cases hx0 : x = 0, {
rw [hx0, zero_mul],
change ¬positive (0 - 0),
rw sub_zero,
exact zero_nonpos,
},
by_cases hy0 : y = 0, {
rw [hy0, mul_zero],
change ¬positive (0 - 0),
rw sub_zero,
exact zero_nonpos,
}, {
have : x * y ≠ 0,
apply mul_nzero; assumption,
cases exists_rep x with a ha,
cases exists_rep y with b hb,
subst ha, subst hb,
change ¬positive (0 - ⟦a⟧ * ⟦b⟧),
change ¬positive (0 - ⟦a⟧) at hx,
change ¬positive (0 - ⟦b⟧) at hy,
rw zero_sub at *,
apply neg_pos_impl_nonpos,
rw neg_neg,
apply pos_mul_closed,
all_goals {
-- Give lean a vague helping hand
rw ←@neg_neg real _ ⟦_⟧,
apply nzero_npos_impl_neg_pos,
assume h,
rw ←neg_neg (0 : real) at h,
rw ←neg_eq at h,
rw neg_zero at h,
contradiction,
assumption,
},
},
end
private theorem le_trans : x ≤ y → y ≤ z → x ≤ z :=
begin
assume hxy hyz,
by_cases hxeqy : x - y = 0, {
rw sub_to_zero_iff_eq at hxeqy,
subst hxeqy,
assumption,
},
by_cases hyeqz : y - z = 0, {
rw sub_to_zero_iff_eq at hyeqz,
subst hyeqz,
assumption,
},
cases exists_rep x with a ha,
cases exists_rep y with b hb,
cases exists_rep z with c hc,
subst ha, subst hb, subst hc,
change ¬positive (⟦a⟧ - ⟦c⟧ : real),
change ¬positive (⟦a⟧ - ⟦b⟧ : real) at hxy,
change ¬positive (⟦b⟧ - ⟦c⟧ : real) at hyz,
have hxy2 := nzero_npos_impl_neg_pos hxeqy hxy,
have hyz2 := nzero_npos_impl_neg_pos hyeqz hyz,
clear hxeqy hyeqz hxy hyz,
apply neg_pos_impl_nonpos,
rw [sub_def, neg_distr, neg_neg] at *,
rw ←add_zero (-_),
rw ←add_neg ⟦b⟧,
rw ←add_assoc,
rw add_assoc,
apply pos_add_closed; assumption,
end
private theorem le_total_order : x ≤ y ∨ y ≤ x :=
begin
by_cases h : x ≤ y, {
left, assumption,
}, {
right,
change ¬positive (y - x),
change ¬¬positive (x - y) at h,
rw not_not at h,
apply neg_pos_impl_nonpos,
rwa neg_sub,
},
end
private theorem le_antisymm : x ≤ y → y ≤ x → x = y :=
begin
intros hxy hyx,
by_cases h : x - y = 0, {
rwa ←sub_to_zero_iff_eq,
}, {
exfalso,
change ¬positive (x - y) at hxy,
change ¬positive (y - x) at hyx,
have := nzero_npos_impl_neg_pos h hxy,
rw neg_sub at this,
contradiction,
},
end
instance: ordered_myfield real := ⟨
by apply_instance,
le_add_right,
zero_le_mul,
le_trans,
le_total_order,
le_antisymm
⟩
end real
end hidden |
a94b32f925577ecd3025ca986c255f092fc61f78 | 9028d228ac200bbefe3a711342514dd4e4458bff | /src/analysis/calculus/fderiv.lean | 008d07193ad17eb00844168033479962243bb5c1 | [
"Apache-2.0"
] | permissive | mcncm/mathlib | 8d25099344d9d2bee62822cb9ed43aa3e09fa05e | fde3d78cadeec5ef827b16ae55664ef115e66f57 | refs/heads/master | 1,672,743,316,277 | 1,602,618,514,000 | 1,602,618,514,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 117,371 | lean | /-
Copyright (c) 2019 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Sébastien Gouëzel, Yury Kudryashov
-/
import analysis.calculus.tangent_cone
import analysis.normed_space.units
/-!
# The Fréchet derivative
Let `E` and `F` be normed spaces, `f : E → F`, and `f' : E →L[𝕜] F` a
continuous 𝕜-linear map, where `𝕜` is a non-discrete normed field. Then
`has_fderiv_within_at f f' s x`
says that `f` has derivative `f'` at `x`, where the domain of interest
is restricted to `s`. We also have
`has_fderiv_at f f' x := has_fderiv_within_at f f' x univ`
Finally,
`has_strict_fderiv_at f f' x`
means that `f : E → F` has derivative `f' : E →L[𝕜] F` in the sense of strict differentiability,
i.e., `f y - f z - f'(y - z) = o(y - z)` as `y, z → x`. This notion is used in the inverse
function theorem, and is defined here only to avoid proving theorems like
`is_bounded_bilinear_map.has_fderiv_at` twice: first for `has_fderiv_at`, then for
`has_strict_fderiv_at`.
## Main results
In addition to the definition and basic properties of the derivative, this file contains the
usual formulas (and existence assertions) for the derivative of
* constants
* the identity
* bounded linear maps
* bounded bilinear maps
* sum of two functions
* sum of finitely many functions
* multiplication of a function by a scalar constant
* negative of a function
* subtraction of two functions
* multiplication of a function by a scalar function
* multiplication of two scalar functions
* composition of functions (the chain rule)
* inverse function (assuming that it exists; the inverse function theorem is in `inverse.lean`)
For most binary operations we also define `const_op` and `op_const` theorems for the cases when
the first or second argument is a constant. This makes writing chains of `has_deriv_at`'s easier,
and they more frequently lead to the desired result.
One can also interpret the derivative of a function `f : 𝕜 → E` as an element of `E` (by identifying
a linear function from `𝕜` to `E` with its value at `1`). Results on the Fréchet derivative are
translated to this more elementary point of view on the derivative in the file `deriv.lean`. The
derivative of polynomials is handled there, as it is naturally one-dimensional.
The simplifier is set up to prove automatically that some functions are differentiable, or
differentiable at a point (but not differentiable on a set or within a set at a point, as checking
automatically that the good domains are mapped one to the other when using composition is not
something the simplifier can easily do). This means that one can write
`example (x : ℝ) : differentiable ℝ (λ x, sin (exp (3 + x^2)) - 5 * cos x) := by simp`.
If there are divisions, one needs to supply to the simplifier proofs that the denominators do
not vanish, as in
```lean
example (x : ℝ) (h : 1 + sin x ≠ 0) : differentiable_at ℝ (λ x, exp x / (1 + sin x)) x :=
by simp [h]
```
Of course, these examples only work once `exp`, `cos` and `sin` have been shown to be
differentiable, in `analysis.special_functions.trigonometric`.
The simplifier is not set up to compute the Fréchet derivative of maps (as these are in general
complicated multidimensional linear maps), but it will compute one-dimensional derivatives,
see `deriv.lean`.
## Implementation details
The derivative is defined in terms of the `is_o` relation, but also
characterized in terms of the `tendsto` relation.
We also introduce predicates `differentiable_within_at 𝕜 f s x` (where `𝕜` is the base field,
`f` the function to be differentiated, `x` the point at which the derivative is asserted to exist,
and `s` the set along which the derivative is defined), as well as `differentiable_at 𝕜 f x`,
`differentiable_on 𝕜 f s` and `differentiable 𝕜 f` to express the existence of a derivative.
To be able to compute with derivatives, we write `fderiv_within 𝕜 f s x` and `fderiv 𝕜 f x`
for some choice of a derivative if it exists, and the zero function otherwise. This choice only
behaves well along sets for which the derivative is unique, i.e., those for which the tangent
directions span a dense subset of the whole space. The predicates `unique_diff_within_at s x` and
`unique_diff_on s`, defined in `tangent_cone.lean` express this property. We prove that indeed
they imply the uniqueness of the derivative. This is satisfied for open subsets, and in particular
for `univ`. This uniqueness only holds when the field is non-discrete, which we request at the very
beginning: otherwise, a derivative can be defined, but it has no interesting properties whatsoever.
To make sure that the simplifier can prove automatically that functions are differentiable, we tag
many lemmas with the `simp` attribute, for instance those saying that the sum of differentiable
functions is differentiable, as well as their product, their cartesian product, and so on. A notable
exception is the chain rule: we do not mark as a simp lemma the fact that, if `f` and `g` are
differentiable, then their composition also is: `simp` would always be able to match this lemma,
by taking `f` or `g` to be the identity. Instead, for every reasonable function (say, `exp`),
we add a lemma that if `f` is differentiable then so is `(λ x, exp (f x))`. This means adding
some boilerplate lemmas, but these can also be useful in their own right.
Tests for this ability of the simplifier (with more examples) are provided in
`tests/differentiable.lean`.
## Tags
derivative, differentiable, Fréchet, calculus
-/
open filter asymptotics continuous_linear_map set metric
open_locale topological_space classical nnreal
noncomputable theory
section
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
variables {E : Type*} [normed_group E] [normed_space 𝕜 E]
variables {F : Type*} [normed_group F] [normed_space 𝕜 F]
variables {G : Type*} [normed_group G] [normed_space 𝕜 G]
variables {G' : Type*} [normed_group G'] [normed_space 𝕜 G']
/-- A function `f` has the continuous linear map `f'` as derivative along the filter `L` if
`f x' = f x + f' (x' - x) + o (x' - x)` when `x'` converges along the filter `L`. This definition
is designed to be specialized for `L = 𝓝 x` (in `has_fderiv_at`), giving rise to the usual notion
of Fréchet derivative, and for `L = 𝓝[s] x` (in `has_fderiv_within_at`), giving rise to
the notion of Fréchet derivative along the set `s`. -/
def has_fderiv_at_filter (f : E → F) (f' : E →L[𝕜] F) (x : E) (L : filter E) :=
is_o (λ x', f x' - f x - f' (x' - x)) (λ x', x' - x) L
/-- A function `f` has the continuous linear map `f'` as derivative at `x` within a set `s` if
`f x' = f x + f' (x' - x) + o (x' - x)` when `x'` tends to `x` inside `s`. -/
def has_fderiv_within_at (f : E → F) (f' : E →L[𝕜] F) (s : set E) (x : E) :=
has_fderiv_at_filter f f' x (𝓝[s] x)
/-- A function `f` has the continuous linear map `f'` as derivative at `x` if
`f x' = f x + f' (x' - x) + o (x' - x)` when `x'` tends to `x`. -/
def has_fderiv_at (f : E → F) (f' : E →L[𝕜] F) (x : E) :=
has_fderiv_at_filter f f' x (𝓝 x)
/-- A function `f` has derivative `f'` at `a` in the sense of *strict differentiability*
if `f x - f y - f' (x - y) = o(x - y)` as `x, y → a`. This form of differentiability is required,
e.g., by the inverse function theorem. Any `C^1` function on a vector space over `ℝ` is strictly
differentiable but this definition works, e.g., for vector spaces over `p`-adic numbers. -/
def has_strict_fderiv_at (f : E → F) (f' : E →L[𝕜] F) (x : E) :=
is_o (λ p : E × E, f p.1 - f p.2 - f' (p.1 - p.2)) (λ p : E × E, p.1 - p.2) (𝓝 (x, x))
variables (𝕜)
/-- A function `f` is differentiable at a point `x` within a set `s` if it admits a derivative
there (possibly non-unique). -/
def differentiable_within_at (f : E → F) (s : set E) (x : E) :=
∃f' : E →L[𝕜] F, has_fderiv_within_at f f' s x
/-- A function `f` is differentiable at a point `x` if it admits a derivative there (possibly
non-unique). -/
def differentiable_at (f : E → F) (x : E) :=
∃f' : E →L[𝕜] F, has_fderiv_at f f' x
/-- If `f` has a derivative at `x` within `s`, then `fderiv_within 𝕜 f s x` is such a derivative.
Otherwise, it is set to `0`. -/
def fderiv_within (f : E → F) (s : set E) (x : E) : E →L[𝕜] F :=
if h : ∃f', has_fderiv_within_at f f' s x then classical.some h else 0
/-- If `f` has a derivative at `x`, then `fderiv 𝕜 f x` is such a derivative. Otherwise, it is
set to `0`. -/
def fderiv (f : E → F) (x : E) : E →L[𝕜] F :=
if h : ∃f', has_fderiv_at f f' x then classical.some h else 0
/-- `differentiable_on 𝕜 f s` means that `f` is differentiable within `s` at any point of `s`. -/
def differentiable_on (f : E → F) (s : set E) :=
∀x ∈ s, differentiable_within_at 𝕜 f s x
/-- `differentiable 𝕜 f` means that `f` is differentiable at any point. -/
def differentiable (f : E → F) :=
∀x, differentiable_at 𝕜 f x
variables {𝕜}
variables {f f₀ f₁ g : E → F}
variables {f' f₀' f₁' g' : E →L[𝕜] F}
variables (e : E →L[𝕜] F)
variables {x : E}
variables {s t : set E}
variables {L L₁ L₂ : filter E}
lemma fderiv_within_zero_of_not_differentiable_within_at
(h : ¬ differentiable_within_at 𝕜 f s x) : fderiv_within 𝕜 f s x = 0 :=
have ¬ ∃ f', has_fderiv_within_at f f' s x, from h,
by simp [fderiv_within, this]
lemma fderiv_zero_of_not_differentiable_at (h : ¬ differentiable_at 𝕜 f x) : fderiv 𝕜 f x = 0 :=
have ¬ ∃ f', has_fderiv_at f f' x, from h,
by simp [fderiv, this]
section derivative_uniqueness
/- In this section, we discuss the uniqueness of the derivative.
We prove that the definitions `unique_diff_within_at` and `unique_diff_on` indeed imply the
uniqueness of the derivative. -/
/-- If a function f has a derivative f' at x, a rescaled version of f around x converges to f', i.e.,
`n (f (x + (1/n) v) - f x)` converges to `f' v`. More generally, if `c n` tends to infinity and
`c n * d n` tends to `v`, then `c n * (f (x + d n) - f x)` tends to `f' v`. This lemma expresses
this fact, for functions having a derivative within a set. Its specific formulation is useful for
tangent cone related discussions. -/
theorem has_fderiv_within_at.lim (h : has_fderiv_within_at f f' s x) {α : Type*} (l : filter α)
{c : α → 𝕜} {d : α → E} {v : E} (dtop : ∀ᶠ n in l, x + d n ∈ s)
(clim : tendsto (λ n, ∥c n∥) l at_top)
(cdlim : tendsto (λ n, c n • d n) l (𝓝 v)) :
tendsto (λn, c n • (f (x + d n) - f x)) l (𝓝 (f' v)) :=
begin
have tendsto_arg : tendsto (λ n, x + d n) l (𝓝[s] x),
{ conv in (𝓝[s] x) { rw ← add_zero x },
rw [nhds_within, tendsto_inf],
split,
{ apply tendsto_const_nhds.add (tangent_cone_at.lim_zero l clim cdlim) },
{ rwa tendsto_principal } },
have : is_o (λ y, f y - f x - f' (y - x)) (λ y, y - x) (𝓝[s] x) := h,
have : is_o (λ n, f (x + d n) - f x - f' ((x + d n) - x)) (λ n, (x + d n) - x) l :=
this.comp_tendsto tendsto_arg,
have : is_o (λ n, f (x + d n) - f x - f' (d n)) d l := by simpa only [add_sub_cancel'],
have : is_o (λn, c n • (f (x + d n) - f x - f' (d n))) (λn, c n • d n) l :=
(is_O_refl c l).smul_is_o this,
have : is_o (λn, c n • (f (x + d n) - f x - f' (d n))) (λn, (1:ℝ)) l :=
this.trans_is_O (is_O_one_of_tendsto ℝ cdlim),
have L1 : tendsto (λn, c n • (f (x + d n) - f x - f' (d n))) l (𝓝 0) :=
(is_o_one_iff ℝ).1 this,
have L2 : tendsto (λn, f' (c n • d n)) l (𝓝 (f' v)) :=
tendsto.comp f'.cont.continuous_at cdlim,
have L3 : tendsto (λn, (c n • (f (x + d n) - f x - f' (d n)) + f' (c n • d n)))
l (𝓝 (0 + f' v)) :=
L1.add L2,
have : (λn, (c n • (f (x + d n) - f x - f' (d n)) + f' (c n • d n)))
= (λn, c n • (f (x + d n) - f x)),
by { ext n, simp [smul_add, smul_sub] },
rwa [this, zero_add] at L3
end
/-- `unique_diff_within_at` achieves its goal: it implies the uniqueness of the derivative. -/
theorem unique_diff_within_at.eq (H : unique_diff_within_at 𝕜 s x)
(h : has_fderiv_within_at f f' s x) (h₁ : has_fderiv_within_at f f₁' s x) : f' = f₁' :=
begin
have A : ∀y ∈ tangent_cone_at 𝕜 s x, f' y = f₁' y,
{ rintros y ⟨c, d, dtop, clim, cdlim⟩,
exact tendsto_nhds_unique (h.lim at_top dtop clim cdlim) (h₁.lim at_top dtop clim cdlim) },
have B : ∀y ∈ submodule.span 𝕜 (tangent_cone_at 𝕜 s x), f' y = f₁' y,
{ assume y hy,
apply submodule.span_induction hy,
{ exact λy hy, A y hy },
{ simp only [continuous_linear_map.map_zero] },
{ simp {contextual := tt} },
{ simp {contextual := tt} } },
have C : ∀y ∈ closure ((submodule.span 𝕜 (tangent_cone_at 𝕜 s x)) : set E), f' y = f₁' y,
{ assume y hy,
let K := {y | f' y = f₁' y},
have : (submodule.span 𝕜 (tangent_cone_at 𝕜 s x) : set E) ⊆ K := B,
have : closure (submodule.span 𝕜 (tangent_cone_at 𝕜 s x) : set E) ⊆ closure K :=
closure_mono this,
have : y ∈ closure K := this hy,
rwa (is_closed_eq f'.continuous f₁'.continuous).closure_eq at this },
rw H.1 at C,
ext y,
exact C y (mem_univ _)
end
theorem unique_diff_on.eq (H : unique_diff_on 𝕜 s) (hx : x ∈ s)
(h : has_fderiv_within_at f f' s x) (h₁ : has_fderiv_within_at f f₁' s x) : f' = f₁' :=
unique_diff_within_at.eq (H x hx) h h₁
end derivative_uniqueness
section fderiv_properties
/-! ### Basic properties of the derivative -/
theorem has_fderiv_at_filter_iff_tendsto :
has_fderiv_at_filter f f' x L ↔
tendsto (λ x', ∥x' - x∥⁻¹ * ∥f x' - f x - f' (x' - x)∥) L (𝓝 0) :=
have h : ∀ x', ∥x' - x∥ = 0 → ∥f x' - f x - f' (x' - x)∥ = 0, from λ x' hx',
by { rw [sub_eq_zero.1 (norm_eq_zero.1 hx')], simp },
begin
unfold has_fderiv_at_filter,
rw [←is_o_norm_left, ←is_o_norm_right, is_o_iff_tendsto h],
exact tendsto_congr (λ _, div_eq_inv_mul),
end
theorem has_fderiv_within_at_iff_tendsto : has_fderiv_within_at f f' s x ↔
tendsto (λ x', ∥x' - x∥⁻¹ * ∥f x' - f x - f' (x' - x)∥) (𝓝[s] x) (𝓝 0) :=
has_fderiv_at_filter_iff_tendsto
theorem has_fderiv_at_iff_tendsto : has_fderiv_at f f' x ↔
tendsto (λ x', ∥x' - x∥⁻¹ * ∥f x' - f x - f' (x' - x)∥) (𝓝 x) (𝓝 0) :=
has_fderiv_at_filter_iff_tendsto
theorem has_fderiv_at_iff_is_o_nhds_zero : has_fderiv_at f f' x ↔
is_o (λh, f (x + h) - f x - f' h) (λh, h) (𝓝 0) :=
begin
split,
{ assume H,
have : tendsto (λ (z : E), z + x) (𝓝 0) (𝓝 (0 + x)),
from tendsto_id.add tendsto_const_nhds,
rw [zero_add] at this,
refine (H.comp_tendsto this).congr _ _;
intro z; simp only [function.comp, add_sub_cancel', add_comm z] },
{ assume H,
have : tendsto (λ (z : E), z - x) (𝓝 x) (𝓝 (x - x)),
from tendsto_id.sub tendsto_const_nhds,
rw [sub_self] at this,
refine (H.comp_tendsto this).congr _ _;
intro z; simp only [function.comp, add_sub_cancel'_right] }
end
/-- Converse to the mean value inequality: if `f` is differentiable at `x₀` and `C`-lipschitz
on a neighborhood of `x₀` then it its derivative at `x₀` has norm bounded by `C`. -/
lemma has_fderiv_at.le_of_lip {f : E → F} {f' : E →L[𝕜] F} {x₀ : E} (hf : has_fderiv_at f f' x₀)
{s : set E} (hs : s ∈ 𝓝 x₀) {C : ℝ≥0} (hlip : lipschitz_on_with C f s) : ∥f'∥ ≤ C :=
begin
replace hf : ∀ ε > 0, ∃ δ > 0, ∀ x', ∥x' - x₀∥ < δ → ∥x' - x₀∥⁻¹ * ∥f x' - f x₀ - f' (x' - x₀)∥ < ε,
by simpa [has_fderiv_at_iff_tendsto, normed_group.tendsto_nhds_nhds] using hf,
obtain ⟨ε, ε_pos, hε⟩ : ∃ ε > 0, ball x₀ ε ⊆ s := mem_nhds_iff.mp hs,
apply real.le_of_forall_epsilon_le,
intros η η_pos,
rcases hf η η_pos with ⟨δ, δ_pos, h⟩, clear hf,
apply op_norm_le_of_ball (lt_min ε_pos δ_pos) (by linarith [C.coe_nonneg]: (0 : ℝ) ≤ C + η),
intros u u_in,
let x := x₀ + u,
rw show u = x - x₀, by rw [add_sub_cancel'],
have xε : x ∈ ball x₀ ε,
by simpa [dist_eq_norm] using ball_subset_ball (min_le_left ε δ) u_in,
have xδ : ∥x - x₀∥ < δ,
by simpa [dist_eq_norm] using ball_subset_ball (min_le_right ε δ) u_in,
replace h : ∥f x - f x₀ - f' (x - x₀)∥ ≤ η*∥x - x₀∥,
{ by_cases H : x - x₀ = 0,
{ simp [eq_of_sub_eq_zero H] },
{ exact (inv_mul_le_iff' $ norm_pos_iff.mpr H).mp (le_of_lt $ h x xδ) } },
have := hlip.norm_sub_le (hε xε) (hε $ mem_ball_self ε_pos),
calc ∥f' (x - x₀)∥ ≤ ∥f x - f x₀∥ + ∥f x - f x₀ - f' (x - x₀)∥ : norm_le_insert _ _
... ≤ (C + η) * ∥x - x₀∥ : by linarith,
end
theorem has_fderiv_at_filter.mono (h : has_fderiv_at_filter f f' x L₂) (hst : L₁ ≤ L₂) :
has_fderiv_at_filter f f' x L₁ :=
h.mono hst
theorem has_fderiv_within_at.mono (h : has_fderiv_within_at f f' t x) (hst : s ⊆ t) :
has_fderiv_within_at f f' s x :=
h.mono (nhds_within_mono _ hst)
theorem has_fderiv_at.has_fderiv_at_filter (h : has_fderiv_at f f' x) (hL : L ≤ 𝓝 x) :
has_fderiv_at_filter f f' x L :=
h.mono hL
theorem has_fderiv_at.has_fderiv_within_at
(h : has_fderiv_at f f' x) : has_fderiv_within_at f f' s x :=
h.has_fderiv_at_filter inf_le_left
lemma has_fderiv_within_at.differentiable_within_at (h : has_fderiv_within_at f f' s x) :
differentiable_within_at 𝕜 f s x :=
⟨f', h⟩
lemma has_fderiv_at.differentiable_at (h : has_fderiv_at f f' x) : differentiable_at 𝕜 f x :=
⟨f', h⟩
@[simp] lemma has_fderiv_within_at_univ :
has_fderiv_within_at f f' univ x ↔ has_fderiv_at f f' x :=
by { simp only [has_fderiv_within_at, nhds_within_univ], refl }
lemma has_strict_fderiv_at.is_O_sub (hf : has_strict_fderiv_at f f' x) :
is_O (λ p : E × E, f p.1 - f p.2) (λ p : E × E, p.1 - p.2) (𝓝 (x, x)) :=
hf.is_O.congr_of_sub.2 (f'.is_O_comp _ _)
lemma has_fderiv_at_filter.is_O_sub (h : has_fderiv_at_filter f f' x L) :
is_O (λ x', f x' - f x) (λ x', x' - x) L :=
h.is_O.congr_of_sub.2 (f'.is_O_sub _ _)
protected lemma has_strict_fderiv_at.has_fderiv_at (hf : has_strict_fderiv_at f f' x) :
has_fderiv_at f f' x :=
begin
rw [has_fderiv_at, has_fderiv_at_filter, is_o_iff],
exact (λ c hc, tendsto_id.prod_mk_nhds tendsto_const_nhds (is_o_iff.1 hf hc))
end
protected lemma has_strict_fderiv_at.differentiable_at (hf : has_strict_fderiv_at f f' x) :
differentiable_at 𝕜 f x :=
hf.has_fderiv_at.differentiable_at
/-- Directional derivative agrees with `has_fderiv`. -/
lemma has_fderiv_at.lim (hf : has_fderiv_at f f' x) (v : E) {α : Type*} {c : α → 𝕜}
{l : filter α} (hc : tendsto (λ n, ∥c n∥) l at_top) :
tendsto (λ n, (c n) • (f (x + (c n)⁻¹ • v) - f x)) l (𝓝 (f' v)) :=
begin
refine (has_fderiv_within_at_univ.2 hf).lim _ (univ_mem_sets' (λ _, trivial)) hc _,
assume U hU,
refine (eventually_ne_of_tendsto_norm_at_top hc (0:𝕜)).mono (λ y hy, _),
convert mem_of_nhds hU,
dsimp only,
rw [← mul_smul, mul_inv_cancel hy, one_smul]
end
theorem has_fderiv_at_unique
(h₀ : has_fderiv_at f f₀' x) (h₁ : has_fderiv_at f f₁' x) : f₀' = f₁' :=
begin
rw ← has_fderiv_within_at_univ at h₀ h₁,
exact unique_diff_within_at_univ.eq h₀ h₁
end
lemma has_fderiv_within_at_inter' (h : t ∈ 𝓝[s] x) :
has_fderiv_within_at f f' (s ∩ t) x ↔ has_fderiv_within_at f f' s x :=
by simp [has_fderiv_within_at, nhds_within_restrict'' s h]
lemma has_fderiv_within_at_inter (h : t ∈ 𝓝 x) :
has_fderiv_within_at f f' (s ∩ t) x ↔ has_fderiv_within_at f f' s x :=
by simp [has_fderiv_within_at, nhds_within_restrict' s h]
lemma has_fderiv_within_at.union (hs : has_fderiv_within_at f f' s x) (ht : has_fderiv_within_at f f' t x) :
has_fderiv_within_at f f' (s ∪ t) x :=
begin
simp only [has_fderiv_within_at, nhds_within_union],
exact hs.join ht,
end
lemma has_fderiv_within_at.nhds_within (h : has_fderiv_within_at f f' s x)
(ht : s ∈ 𝓝[t] x) : has_fderiv_within_at f f' t x :=
(has_fderiv_within_at_inter' ht).1 (h.mono (inter_subset_right _ _))
lemma has_fderiv_within_at.has_fderiv_at (h : has_fderiv_within_at f f' s x) (hs : s ∈ 𝓝 x) :
has_fderiv_at f f' x :=
by rwa [← univ_inter s, has_fderiv_within_at_inter hs, has_fderiv_within_at_univ] at h
lemma differentiable_within_at.has_fderiv_within_at (h : differentiable_within_at 𝕜 f s x) :
has_fderiv_within_at f (fderiv_within 𝕜 f s x) s x :=
begin
dunfold fderiv_within,
dunfold differentiable_within_at at h,
rw dif_pos h,
exact classical.some_spec h
end
lemma differentiable_at.has_fderiv_at (h : differentiable_at 𝕜 f x) :
has_fderiv_at f (fderiv 𝕜 f x) x :=
begin
dunfold fderiv,
dunfold differentiable_at at h,
rw dif_pos h,
exact classical.some_spec h
end
lemma has_fderiv_at.fderiv (h : has_fderiv_at f f' x) : fderiv 𝕜 f x = f' :=
by { ext, rw has_fderiv_at_unique h h.differentiable_at.has_fderiv_at }
/-- Converse to the mean value inequality: if `f` is differentiable at `x₀` and `C`-lipschitz
on a neighborhood of `x₀` then it its derivative at `x₀` has norm bounded by `C`.
Version using `fderiv`. -/
lemma fderiv_at.le_of_lip {f : E → F} {x₀ : E} (hf : differentiable_at 𝕜 f x₀)
{s : set E} (hs : s ∈ 𝓝 x₀) {C : ℝ≥0} (hlip : lipschitz_on_with C f s) : ∥fderiv 𝕜 f x₀∥ ≤ C :=
hf.has_fderiv_at.le_of_lip hs hlip
lemma has_fderiv_within_at.fderiv_within
(h : has_fderiv_within_at f f' s x) (hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 f s x = f' :=
(hxs.eq h h.differentiable_within_at.has_fderiv_within_at).symm
/-- If `x` is not in the closure of `s`, then `f` has any derivative at `x` within `s`,
as this statement is empty. -/
lemma has_fderiv_within_at_of_not_mem_closure (h : x ∉ closure s) :
has_fderiv_within_at f f' s x :=
begin
simp [mem_closure_iff_nhds_within_ne_bot, ne_bot] at h,
simp [has_fderiv_within_at, has_fderiv_at_filter, h, is_o, is_O_with],
end
lemma differentiable_within_at.mono (h : differentiable_within_at 𝕜 f t x) (st : s ⊆ t) :
differentiable_within_at 𝕜 f s x :=
begin
rcases h with ⟨f', hf'⟩,
exact ⟨f', hf'.mono st⟩
end
lemma differentiable_within_at_univ :
differentiable_within_at 𝕜 f univ x ↔ differentiable_at 𝕜 f x :=
by simp only [differentiable_within_at, has_fderiv_within_at_univ, differentiable_at]
lemma differentiable_within_at_inter (ht : t ∈ 𝓝 x) :
differentiable_within_at 𝕜 f (s ∩ t) x ↔ differentiable_within_at 𝕜 f s x :=
by simp only [differentiable_within_at, has_fderiv_within_at, has_fderiv_at_filter,
nhds_within_restrict' s ht]
lemma differentiable_within_at_inter' (ht : t ∈ 𝓝[s] x) :
differentiable_within_at 𝕜 f (s ∩ t) x ↔ differentiable_within_at 𝕜 f s x :=
by simp only [differentiable_within_at, has_fderiv_within_at, has_fderiv_at_filter,
nhds_within_restrict'' s ht]
lemma differentiable_at.differentiable_within_at
(h : differentiable_at 𝕜 f x) : differentiable_within_at 𝕜 f s x :=
(differentiable_within_at_univ.2 h).mono (subset_univ _)
lemma differentiable.differentiable_at (h : differentiable 𝕜 f) :
differentiable_at 𝕜 f x :=
h x
lemma differentiable_within_at.differentiable_at
(h : differentiable_within_at 𝕜 f s x) (hs : s ∈ 𝓝 x) : differentiable_at 𝕜 f x :=
h.imp (λ f' hf', hf'.has_fderiv_at hs)
lemma differentiable_at.fderiv_within
(h : differentiable_at 𝕜 f x) (hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 f s x = fderiv 𝕜 f x :=
begin
apply has_fderiv_within_at.fderiv_within _ hxs,
exact h.has_fderiv_at.has_fderiv_within_at
end
lemma differentiable_on.mono (h : differentiable_on 𝕜 f t) (st : s ⊆ t) :
differentiable_on 𝕜 f s :=
λx hx, (h x (st hx)).mono st
lemma differentiable_on_univ :
differentiable_on 𝕜 f univ ↔ differentiable 𝕜 f :=
by { simp [differentiable_on, differentiable_within_at_univ], refl }
lemma differentiable.differentiable_on (h : differentiable 𝕜 f) : differentiable_on 𝕜 f s :=
(differentiable_on_univ.2 h).mono (subset_univ _)
lemma differentiable_on_of_locally_differentiable_on
(h : ∀x∈s, ∃u, is_open u ∧ x ∈ u ∧ differentiable_on 𝕜 f (s ∩ u)) : differentiable_on 𝕜 f s :=
begin
assume x xs,
rcases h x xs with ⟨t, t_open, xt, ht⟩,
exact (differentiable_within_at_inter (mem_nhds_sets t_open xt)).1 (ht x ⟨xs, xt⟩)
end
lemma fderiv_within_subset (st : s ⊆ t) (ht : unique_diff_within_at 𝕜 s x)
(h : differentiable_within_at 𝕜 f t x) :
fderiv_within 𝕜 f s x = fderiv_within 𝕜 f t x :=
((differentiable_within_at.has_fderiv_within_at h).mono st).fderiv_within ht
@[simp] lemma fderiv_within_univ : fderiv_within 𝕜 f univ = fderiv 𝕜 f :=
begin
ext x : 1,
by_cases h : differentiable_at 𝕜 f x,
{ apply has_fderiv_within_at.fderiv_within _ unique_diff_within_at_univ,
rw has_fderiv_within_at_univ,
apply h.has_fderiv_at },
{ have : ¬ differentiable_within_at 𝕜 f univ x,
by contrapose! h; rwa ← differentiable_within_at_univ,
rw [fderiv_zero_of_not_differentiable_at h,
fderiv_within_zero_of_not_differentiable_within_at this] }
end
lemma fderiv_within_inter (ht : t ∈ 𝓝 x) (hs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 f (s ∩ t) x = fderiv_within 𝕜 f s x :=
begin
by_cases h : differentiable_within_at 𝕜 f (s ∩ t) x,
{ apply fderiv_within_subset (inter_subset_left _ _) _ ((differentiable_within_at_inter ht).1 h),
apply hs.inter ht },
{ have : ¬ differentiable_within_at 𝕜 f s x,
by contrapose! h; rw differentiable_within_at_inter; assumption,
rw [fderiv_within_zero_of_not_differentiable_within_at h,
fderiv_within_zero_of_not_differentiable_within_at this] }
end
lemma fderiv_within_of_open (hs : is_open s) (hx : x ∈ s) :
fderiv_within 𝕜 f s x = fderiv 𝕜 f x :=
begin
have : s = univ ∩ s, by simp only [univ_inter],
rw [this, ← fderiv_within_univ],
exact fderiv_within_inter (mem_nhds_sets hs hx) (unique_diff_on_univ _ (mem_univ _))
end
lemma fderiv_within_eq_fderiv (hs : unique_diff_within_at 𝕜 s x) (h : differentiable_at 𝕜 f x) :
fderiv_within 𝕜 f s x = fderiv 𝕜 f x :=
begin
rw ← fderiv_within_univ,
exact fderiv_within_subset (subset_univ _) hs h.differentiable_within_at
end
end fderiv_properties
section continuous
/-! ### Deducing continuity from differentiability -/
theorem has_fderiv_at_filter.tendsto_nhds
(hL : L ≤ 𝓝 x) (h : has_fderiv_at_filter f f' x L) :
tendsto f L (𝓝 (f x)) :=
begin
have : tendsto (λ x', f x' - f x) L (𝓝 0),
{ refine h.is_O_sub.trans_tendsto (tendsto.mono_left _ hL),
rw ← sub_self x, exact tendsto_id.sub tendsto_const_nhds },
have := tendsto.add this tendsto_const_nhds,
rw zero_add (f x) at this,
exact this.congr (by simp)
end
theorem has_fderiv_within_at.continuous_within_at
(h : has_fderiv_within_at f f' s x) : continuous_within_at f s x :=
has_fderiv_at_filter.tendsto_nhds inf_le_left h
theorem has_fderiv_at.continuous_at (h : has_fderiv_at f f' x) :
continuous_at f x :=
has_fderiv_at_filter.tendsto_nhds (le_refl _) h
lemma differentiable_within_at.continuous_within_at (h : differentiable_within_at 𝕜 f s x) :
continuous_within_at f s x :=
let ⟨f', hf'⟩ := h in hf'.continuous_within_at
lemma differentiable_at.continuous_at (h : differentiable_at 𝕜 f x) : continuous_at f x :=
let ⟨f', hf'⟩ := h in hf'.continuous_at
lemma differentiable_on.continuous_on (h : differentiable_on 𝕜 f s) : continuous_on f s :=
λx hx, (h x hx).continuous_within_at
lemma differentiable.continuous (h : differentiable 𝕜 f) : continuous f :=
continuous_iff_continuous_at.2 $ λx, (h x).continuous_at
protected lemma has_strict_fderiv_at.continuous_at (hf : has_strict_fderiv_at f f' x) :
continuous_at f x :=
hf.has_fderiv_at.continuous_at
lemma has_strict_fderiv_at.is_O_sub_rev {f' : E ≃L[𝕜] F}
(hf : has_strict_fderiv_at f (f' : E →L[𝕜] F) x) :
is_O (λ p : E × E, p.1 - p.2) (λ p : E × E, f p.1 - f p.2) (𝓝 (x, x)) :=
((f'.is_O_comp_rev _ _).trans (hf.trans_is_O (f'.is_O_comp_rev _ _)).right_is_O_add).congr
(λ _, rfl) (λ _, sub_add_cancel _ _)
lemma has_fderiv_at_filter.is_O_sub_rev {f' : E ≃L[𝕜] F}
(hf : has_fderiv_at_filter f (f' : E →L[𝕜] F) x L) :
is_O (λ x', x' - x) (λ x', f x' - f x) L :=
((f'.is_O_sub_rev _ _).trans (hf.trans_is_O (f'.is_O_sub_rev _ _)).right_is_O_add).congr
(λ _, rfl) (λ _, sub_add_cancel _ _)
end continuous
section congr
/-! ### congr properties of the derivative -/
theorem filter.eventually_eq.has_strict_fderiv_at_iff
(h : f₀ =ᶠ[𝓝 x] f₁) (h' : ∀ y, f₀' y = f₁' y) :
has_strict_fderiv_at f₀ f₀' x ↔ has_strict_fderiv_at f₁ f₁' x :=
begin
refine is_o_congr ((h.prod_mk_nhds h).mono _) (eventually_of_forall $ λ _, rfl),
rintros p ⟨hp₁, hp₂⟩,
simp only [*]
end
theorem has_strict_fderiv_at.congr_of_eventually_eq (h : has_strict_fderiv_at f f' x)
(h₁ : f =ᶠ[𝓝 x] f₁) : has_strict_fderiv_at f₁ f' x :=
(h₁.has_strict_fderiv_at_iff (λ _, rfl)).1 h
theorem filter.eventually_eq.has_fderiv_at_filter_iff
(h₀ : f₀ =ᶠ[L] f₁) (hx : f₀ x = f₁ x) (h₁ : ∀ x, f₀' x = f₁' x) :
has_fderiv_at_filter f₀ f₀' x L ↔ has_fderiv_at_filter f₁ f₁' x L :=
is_o_congr (h₀.mono $ λ y hy, by simp only [hy, h₁, hx]) (eventually_of_forall $ λ _, rfl)
lemma has_fderiv_at_filter.congr_of_eventually_eq (h : has_fderiv_at_filter f f' x L)
(hL : f₁ =ᶠ[L] f) (hx : f₁ x = f x) : has_fderiv_at_filter f₁ f' x L :=
(hL.has_fderiv_at_filter_iff hx $ λ _, rfl).2 h
lemma has_fderiv_within_at.congr_mono (h : has_fderiv_within_at f f' s x) (ht : ∀x ∈ t, f₁ x = f x)
(hx : f₁ x = f x) (h₁ : t ⊆ s) : has_fderiv_within_at f₁ f' t x :=
has_fderiv_at_filter.congr_of_eventually_eq (h.mono h₁) (filter.mem_inf_sets_of_right ht) hx
lemma has_fderiv_within_at.congr (h : has_fderiv_within_at f f' s x) (hs : ∀x ∈ s, f₁ x = f x)
(hx : f₁ x = f x) : has_fderiv_within_at f₁ f' s x :=
h.congr_mono hs hx (subset.refl _)
lemma has_fderiv_within_at.congr_of_eventually_eq (h : has_fderiv_within_at f f' s x)
(h₁ : f₁ =ᶠ[𝓝[s] x] f) (hx : f₁ x = f x) : has_fderiv_within_at f₁ f' s x :=
has_fderiv_at_filter.congr_of_eventually_eq h h₁ hx
lemma has_fderiv_at.congr_of_eventually_eq (h : has_fderiv_at f f' x)
(h₁ : f₁ =ᶠ[𝓝 x] f) : has_fderiv_at f₁ f' x :=
has_fderiv_at_filter.congr_of_eventually_eq h h₁ (mem_of_nhds h₁ : _)
lemma differentiable_within_at.congr_mono (h : differentiable_within_at 𝕜 f s x)
(ht : ∀x ∈ t, f₁ x = f x) (hx : f₁ x = f x) (h₁ : t ⊆ s) : differentiable_within_at 𝕜 f₁ t x :=
(has_fderiv_within_at.congr_mono h.has_fderiv_within_at ht hx h₁).differentiable_within_at
lemma differentiable_within_at.congr (h : differentiable_within_at 𝕜 f s x)
(ht : ∀x ∈ s, f₁ x = f x) (hx : f₁ x = f x) : differentiable_within_at 𝕜 f₁ s x :=
differentiable_within_at.congr_mono h ht hx (subset.refl _)
lemma differentiable_within_at.congr_of_eventually_eq
(h : differentiable_within_at 𝕜 f s x) (h₁ : f₁ =ᶠ[𝓝[s] x] f)
(hx : f₁ x = f x) : differentiable_within_at 𝕜 f₁ s x :=
(h.has_fderiv_within_at.congr_of_eventually_eq h₁ hx).differentiable_within_at
lemma differentiable_on.congr_mono (h : differentiable_on 𝕜 f s) (h' : ∀x ∈ t, f₁ x = f x)
(h₁ : t ⊆ s) : differentiable_on 𝕜 f₁ t :=
λ x hx, (h x (h₁ hx)).congr_mono h' (h' x hx) h₁
lemma differentiable_on.congr (h : differentiable_on 𝕜 f s) (h' : ∀x ∈ s, f₁ x = f x) :
differentiable_on 𝕜 f₁ s :=
λ x hx, (h x hx).congr h' (h' x hx)
lemma differentiable_on_congr (h' : ∀x ∈ s, f₁ x = f x) :
differentiable_on 𝕜 f₁ s ↔ differentiable_on 𝕜 f s :=
⟨λ h, differentiable_on.congr h (λy hy, (h' y hy).symm),
λ h, differentiable_on.congr h h'⟩
lemma differentiable_at.congr_of_eventually_eq (h : differentiable_at 𝕜 f x) (hL : f₁ =ᶠ[𝓝 x] f) :
differentiable_at 𝕜 f₁ x :=
has_fderiv_at.differentiable_at
(has_fderiv_at_filter.congr_of_eventually_eq h.has_fderiv_at hL (mem_of_nhds hL : _))
lemma differentiable_within_at.fderiv_within_congr_mono (h : differentiable_within_at 𝕜 f s x)
(hs : ∀x ∈ t, f₁ x = f x) (hx : f₁ x = f x) (hxt : unique_diff_within_at 𝕜 t x) (h₁ : t ⊆ s) :
fderiv_within 𝕜 f₁ t x = fderiv_within 𝕜 f s x :=
(has_fderiv_within_at.congr_mono h.has_fderiv_within_at hs hx h₁).fderiv_within hxt
lemma filter.eventually_eq.fderiv_within_eq (hs : unique_diff_within_at 𝕜 s x)
(hL : f₁ =ᶠ[𝓝[s] x] f) (hx : f₁ x = f x) :
fderiv_within 𝕜 f₁ s x = fderiv_within 𝕜 f s x :=
if h : differentiable_within_at 𝕜 f s x
then has_fderiv_within_at.fderiv_within (h.has_fderiv_within_at.congr_of_eventually_eq hL hx) hs
else
have h' : ¬ differentiable_within_at 𝕜 f₁ s x,
from mt (λ h, h.congr_of_eventually_eq (hL.mono $ λ x, eq.symm) hx.symm) h,
by rw [fderiv_within_zero_of_not_differentiable_within_at h,
fderiv_within_zero_of_not_differentiable_within_at h']
lemma fderiv_within_congr (hs : unique_diff_within_at 𝕜 s x)
(hL : ∀y∈s, f₁ y = f y) (hx : f₁ x = f x) :
fderiv_within 𝕜 f₁ s x = fderiv_within 𝕜 f s x :=
begin
apply filter.eventually_eq.fderiv_within_eq hs _ hx,
apply mem_sets_of_superset self_mem_nhds_within,
exact hL
end
lemma filter.eventually_eq.fderiv_eq (hL : f₁ =ᶠ[𝓝 x] f) :
fderiv 𝕜 f₁ x = fderiv 𝕜 f x :=
begin
have A : f₁ x = f x := hL.eq_of_nhds,
rw [← fderiv_within_univ, ← fderiv_within_univ],
rw ← nhds_within_univ at hL,
exact hL.fderiv_within_eq unique_diff_within_at_univ A
end
end congr
section id
/-! ### Derivative of the identity -/
theorem has_strict_fderiv_at_id (x : E) :
has_strict_fderiv_at id (id 𝕜 E) x :=
(is_o_zero _ _).congr_left $ by simp
theorem has_fderiv_at_filter_id (x : E) (L : filter E) :
has_fderiv_at_filter id (id 𝕜 E) x L :=
(is_o_zero _ _).congr_left $ by simp
theorem has_fderiv_within_at_id (x : E) (s : set E) :
has_fderiv_within_at id (id 𝕜 E) s x :=
has_fderiv_at_filter_id _ _
theorem has_fderiv_at_id (x : E) : has_fderiv_at id (id 𝕜 E) x :=
has_fderiv_at_filter_id _ _
@[simp] lemma differentiable_at_id : differentiable_at 𝕜 id x :=
(has_fderiv_at_id x).differentiable_at
@[simp] lemma differentiable_at_id' : differentiable_at 𝕜 (λ x, x) x :=
(has_fderiv_at_id x).differentiable_at
lemma differentiable_within_at_id : differentiable_within_at 𝕜 id s x :=
differentiable_at_id.differentiable_within_at
@[simp] lemma differentiable_id : differentiable 𝕜 (id : E → E) :=
λx, differentiable_at_id
@[simp] lemma differentiable_id' : differentiable 𝕜 (λ (x : E), x) :=
λx, differentiable_at_id
lemma differentiable_on_id : differentiable_on 𝕜 id s :=
differentiable_id.differentiable_on
lemma fderiv_id : fderiv 𝕜 id x = id 𝕜 E :=
has_fderiv_at.fderiv (has_fderiv_at_id x)
@[simp] lemma fderiv_id' : fderiv 𝕜 (λ (x : E), x) x = continuous_linear_map.id 𝕜 E :=
fderiv_id
lemma fderiv_within_id (hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 id s x = id 𝕜 E :=
begin
rw differentiable_at.fderiv_within (differentiable_at_id) hxs,
exact fderiv_id
end
lemma fderiv_within_id' (hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 (λ (x : E), x) s x = continuous_linear_map.id 𝕜 E :=
fderiv_within_id hxs
end id
section const
/-! ### derivative of a constant function -/
theorem has_strict_fderiv_at_const (c : F) (x : E) :
has_strict_fderiv_at (λ _, c) (0 : E →L[𝕜] F) x :=
(is_o_zero _ _).congr_left $ λ _, by simp only [zero_apply, sub_self]
theorem has_fderiv_at_filter_const (c : F) (x : E) (L : filter E) :
has_fderiv_at_filter (λ x, c) (0 : E →L[𝕜] F) x L :=
(is_o_zero _ _).congr_left $ λ _, by simp only [zero_apply, sub_self]
theorem has_fderiv_within_at_const (c : F) (x : E) (s : set E) :
has_fderiv_within_at (λ x, c) (0 : E →L[𝕜] F) s x :=
has_fderiv_at_filter_const _ _ _
theorem has_fderiv_at_const (c : F) (x : E) :
has_fderiv_at (λ x, c) (0 : E →L[𝕜] F) x :=
has_fderiv_at_filter_const _ _ _
@[simp] lemma differentiable_at_const (c : F) : differentiable_at 𝕜 (λx, c) x :=
⟨0, has_fderiv_at_const c x⟩
lemma differentiable_within_at_const (c : F) : differentiable_within_at 𝕜 (λx, c) s x :=
differentiable_at.differentiable_within_at (differentiable_at_const _)
lemma fderiv_const_apply (c : F) : fderiv 𝕜 (λy, c) x = 0 :=
has_fderiv_at.fderiv (has_fderiv_at_const c x)
@[simp] lemma fderiv_const (c : F) : fderiv 𝕜 (λ (y : E), c) = 0 :=
by { ext m, rw fderiv_const_apply, refl }
lemma fderiv_within_const_apply (c : F) (hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 (λy, c) s x = 0 :=
begin
rw differentiable_at.fderiv_within (differentiable_at_const _) hxs,
exact fderiv_const_apply _
end
@[simp] lemma differentiable_const (c : F) : differentiable 𝕜 (λx : E, c) :=
λx, differentiable_at_const _
lemma differentiable_on_const (c : F) : differentiable_on 𝕜 (λx, c) s :=
(differentiable_const _).differentiable_on
end const
section continuous_linear_map
/-!
### Continuous linear maps
There are currently two variants of these in mathlib, the bundled version
(named `continuous_linear_map`, and denoted `E →L[𝕜] F`), and the unbundled version (with a
predicate `is_bounded_linear_map`). We give statements for both versions. -/
protected theorem continuous_linear_map.has_strict_fderiv_at {x : E} :
has_strict_fderiv_at e e x :=
(is_o_zero _ _).congr_left $ λ x, by simp only [e.map_sub, sub_self]
protected lemma continuous_linear_map.has_fderiv_at_filter :
has_fderiv_at_filter e e x L :=
(is_o_zero _ _).congr_left $ λ x, by simp only [e.map_sub, sub_self]
protected lemma continuous_linear_map.has_fderiv_within_at : has_fderiv_within_at e e s x :=
e.has_fderiv_at_filter
protected lemma continuous_linear_map.has_fderiv_at : has_fderiv_at e e x :=
e.has_fderiv_at_filter
@[simp] protected lemma continuous_linear_map.differentiable_at : differentiable_at 𝕜 e x :=
e.has_fderiv_at.differentiable_at
protected lemma continuous_linear_map.differentiable_within_at : differentiable_within_at 𝕜 e s x :=
e.differentiable_at.differentiable_within_at
protected lemma continuous_linear_map.fderiv : fderiv 𝕜 e x = e :=
e.has_fderiv_at.fderiv
protected lemma continuous_linear_map.fderiv_within (hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 e s x = e :=
begin
rw differentiable_at.fderiv_within e.differentiable_at hxs,
exact e.fderiv
end
@[simp]protected lemma continuous_linear_map.differentiable : differentiable 𝕜 e :=
λx, e.differentiable_at
protected lemma continuous_linear_map.differentiable_on : differentiable_on 𝕜 e s :=
e.differentiable.differentiable_on
lemma is_bounded_linear_map.has_fderiv_at_filter (h : is_bounded_linear_map 𝕜 f) :
has_fderiv_at_filter f h.to_continuous_linear_map x L :=
h.to_continuous_linear_map.has_fderiv_at_filter
lemma is_bounded_linear_map.has_fderiv_within_at (h : is_bounded_linear_map 𝕜 f) :
has_fderiv_within_at f h.to_continuous_linear_map s x :=
h.has_fderiv_at_filter
lemma is_bounded_linear_map.has_fderiv_at (h : is_bounded_linear_map 𝕜 f) :
has_fderiv_at f h.to_continuous_linear_map x :=
h.has_fderiv_at_filter
lemma is_bounded_linear_map.differentiable_at (h : is_bounded_linear_map 𝕜 f) :
differentiable_at 𝕜 f x :=
h.has_fderiv_at.differentiable_at
lemma is_bounded_linear_map.differentiable_within_at (h : is_bounded_linear_map 𝕜 f) :
differentiable_within_at 𝕜 f s x :=
h.differentiable_at.differentiable_within_at
lemma is_bounded_linear_map.fderiv (h : is_bounded_linear_map 𝕜 f) :
fderiv 𝕜 f x = h.to_continuous_linear_map :=
has_fderiv_at.fderiv (h.has_fderiv_at)
lemma is_bounded_linear_map.fderiv_within (h : is_bounded_linear_map 𝕜 f)
(hxs : unique_diff_within_at 𝕜 s x) : fderiv_within 𝕜 f s x = h.to_continuous_linear_map :=
begin
rw differentiable_at.fderiv_within h.differentiable_at hxs,
exact h.fderiv
end
lemma is_bounded_linear_map.differentiable (h : is_bounded_linear_map 𝕜 f) :
differentiable 𝕜 f :=
λx, h.differentiable_at
lemma is_bounded_linear_map.differentiable_on (h : is_bounded_linear_map 𝕜 f) :
differentiable_on 𝕜 f s :=
h.differentiable.differentiable_on
end continuous_linear_map
section composition
/-!
### Derivative of the composition of two functions
For composition lemmas, we put x explicit to help the elaborator, as otherwise Lean tends to
get confused since there are too many possibilities for composition -/
variable (x)
theorem has_fderiv_at_filter.comp {g : F → G} {g' : F →L[𝕜] G}
(hg : has_fderiv_at_filter g g' (f x) (L.map f))
(hf : has_fderiv_at_filter f f' x L) :
has_fderiv_at_filter (g ∘ f) (g'.comp f') x L :=
let eq₁ := (g'.is_O_comp _ _).trans_is_o hf in
let eq₂ := (hg.comp_tendsto tendsto_map).trans_is_O hf.is_O_sub in
by { refine eq₂.triangle (eq₁.congr_left (λ x', _)), simp }
/- A readable version of the previous theorem,
a general form of the chain rule. -/
example {g : F → G} {g' : F →L[𝕜] G}
(hg : has_fderiv_at_filter g g' (f x) (L.map f))
(hf : has_fderiv_at_filter f f' x L) :
has_fderiv_at_filter (g ∘ f) (g'.comp f') x L :=
begin
unfold has_fderiv_at_filter at hg,
have : is_o (λ x', g (f x') - g (f x) - g' (f x' - f x)) (λ x', f x' - f x) L,
from hg.comp_tendsto (le_refl _),
have eq₁ : is_o (λ x', g (f x') - g (f x) - g' (f x' - f x)) (λ x', x' - x) L,
from this.trans_is_O hf.is_O_sub,
have eq₂ : is_o (λ x', f x' - f x - f' (x' - x)) (λ x', x' - x) L,
from hf,
have : is_O
(λ x', g' (f x' - f x - f' (x' - x))) (λ x', f x' - f x - f' (x' - x)) L,
from g'.is_O_comp _ _,
have : is_o (λ x', g' (f x' - f x - f' (x' - x))) (λ x', x' - x) L,
from this.trans_is_o eq₂,
have eq₃ : is_o (λ x', g' (f x' - f x) - (g' (f' (x' - x)))) (λ x', x' - x) L,
by { refine this.congr_left _, simp},
exact eq₁.triangle eq₃
end
theorem has_fderiv_within_at.comp {g : F → G} {g' : F →L[𝕜] G} {t : set F}
(hg : has_fderiv_within_at g g' t (f x)) (hf : has_fderiv_within_at f f' s x) (hst : s ⊆ f ⁻¹' t) :
has_fderiv_within_at (g ∘ f) (g'.comp f') s x :=
begin
apply has_fderiv_at_filter.comp _ (has_fderiv_at_filter.mono hg _) hf,
calc map f (𝓝[s] x)
≤ 𝓝[f '' s] (f x) : hf.continuous_within_at.tendsto_nhds_within_image
... ≤ 𝓝[t] (f x) : nhds_within_mono _ (image_subset_iff.mpr hst)
end
/-- The chain rule. -/
theorem has_fderiv_at.comp {g : F → G} {g' : F →L[𝕜] G}
(hg : has_fderiv_at g g' (f x)) (hf : has_fderiv_at f f' x) :
has_fderiv_at (g ∘ f) (g'.comp f') x :=
(hg.mono hf.continuous_at).comp x hf
theorem has_fderiv_at.comp_has_fderiv_within_at {g : F → G} {g' : F →L[𝕜] G}
(hg : has_fderiv_at g g' (f x)) (hf : has_fderiv_within_at f f' s x) :
has_fderiv_within_at (g ∘ f) (g'.comp f') s x :=
begin
rw ← has_fderiv_within_at_univ at hg,
exact has_fderiv_within_at.comp x hg hf subset_preimage_univ
end
lemma differentiable_within_at.comp {g : F → G} {t : set F}
(hg : differentiable_within_at 𝕜 g t (f x)) (hf : differentiable_within_at 𝕜 f s x)
(h : s ⊆ f ⁻¹' t) : differentiable_within_at 𝕜 (g ∘ f) s x :=
begin
rcases hf with ⟨f', hf'⟩,
rcases hg with ⟨g', hg'⟩,
exact ⟨continuous_linear_map.comp g' f', hg'.comp x hf' h⟩
end
lemma differentiable_within_at.comp' {g : F → G} {t : set F}
(hg : differentiable_within_at 𝕜 g t (f x)) (hf : differentiable_within_at 𝕜 f s x) :
differentiable_within_at 𝕜 (g ∘ f) (s ∩ f⁻¹' t) x :=
hg.comp x (hf.mono (inter_subset_left _ _)) (inter_subset_right _ _)
lemma differentiable_at.comp {g : F → G}
(hg : differentiable_at 𝕜 g (f x)) (hf : differentiable_at 𝕜 f x) :
differentiable_at 𝕜 (g ∘ f) x :=
(hg.has_fderiv_at.comp x hf.has_fderiv_at).differentiable_at
lemma differentiable_at.comp_differentiable_within_at {g : F → G}
(hg : differentiable_at 𝕜 g (f x)) (hf : differentiable_within_at 𝕜 f s x) :
differentiable_within_at 𝕜 (g ∘ f) s x :=
(differentiable_within_at_univ.2 hg).comp x hf (by simp)
lemma fderiv_within.comp {g : F → G} {t : set F}
(hg : differentiable_within_at 𝕜 g t (f x)) (hf : differentiable_within_at 𝕜 f s x)
(h : maps_to f s t) (hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 (g ∘ f) s x = (fderiv_within 𝕜 g t (f x)).comp (fderiv_within 𝕜 f s x) :=
begin
apply has_fderiv_within_at.fderiv_within _ hxs,
exact has_fderiv_within_at.comp x (hg.has_fderiv_within_at) (hf.has_fderiv_within_at) h
end
lemma fderiv.comp {g : F → G}
(hg : differentiable_at 𝕜 g (f x)) (hf : differentiable_at 𝕜 f x) :
fderiv 𝕜 (g ∘ f) x = (fderiv 𝕜 g (f x)).comp (fderiv 𝕜 f x) :=
begin
apply has_fderiv_at.fderiv,
exact has_fderiv_at.comp x hg.has_fderiv_at hf.has_fderiv_at
end
lemma fderiv.comp_fderiv_within {g : F → G}
(hg : differentiable_at 𝕜 g (f x)) (hf : differentiable_within_at 𝕜 f s x)
(hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 (g ∘ f) s x = (fderiv 𝕜 g (f x)).comp (fderiv_within 𝕜 f s x) :=
begin
apply has_fderiv_within_at.fderiv_within _ hxs,
exact has_fderiv_at.comp_has_fderiv_within_at x (hg.has_fderiv_at) (hf.has_fderiv_within_at)
end
lemma differentiable_on.comp {g : F → G} {t : set F}
(hg : differentiable_on 𝕜 g t) (hf : differentiable_on 𝕜 f s) (st : s ⊆ f ⁻¹' t) :
differentiable_on 𝕜 (g ∘ f) s :=
λx hx, differentiable_within_at.comp x (hg (f x) (st hx)) (hf x hx) st
lemma differentiable.comp {g : F → G} (hg : differentiable 𝕜 g) (hf : differentiable 𝕜 f) :
differentiable 𝕜 (g ∘ f) :=
λx, differentiable_at.comp x (hg (f x)) (hf x)
lemma differentiable.comp_differentiable_on {g : F → G} (hg : differentiable 𝕜 g)
(hf : differentiable_on 𝕜 f s) :
differentiable_on 𝕜 (g ∘ f) s :=
(differentiable_on_univ.2 hg).comp hf (by simp)
/-- The chain rule for derivatives in the sense of strict differentiability. -/
protected lemma has_strict_fderiv_at.comp {g : F → G} {g' : F →L[𝕜] G}
(hg : has_strict_fderiv_at g g' (f x)) (hf : has_strict_fderiv_at f f' x) :
has_strict_fderiv_at (λ x, g (f x)) (g'.comp f') x :=
((hg.comp_tendsto (hf.continuous_at.prod_map' hf.continuous_at)).trans_is_O hf.is_O_sub).triangle $
by simpa only [g'.map_sub, f'.coe_comp'] using (g'.is_O_comp _ _).trans_is_o hf
protected lemma differentiable.iterate {f : E → E} (hf : differentiable 𝕜 f) (n : ℕ) :
differentiable 𝕜 (f^[n]) :=
nat.rec_on n differentiable_id (λ n ihn, ihn.comp hf)
protected lemma differentiable_on.iterate {f : E → E} (hf : differentiable_on 𝕜 f s)
(hs : maps_to f s s) (n : ℕ) :
differentiable_on 𝕜 (f^[n]) s :=
nat.rec_on n differentiable_on_id (λ n ihn, ihn.comp hf hs)
variable {x}
protected lemma has_fderiv_at_filter.iterate {f : E → E} {f' : E →L[𝕜] E}
(hf : has_fderiv_at_filter f f' x L) (hL : tendsto f L L) (hx : f x = x) (n : ℕ) :
has_fderiv_at_filter (f^[n]) (f'^n) x L :=
begin
induction n with n ihn,
{ exact has_fderiv_at_filter_id x L },
{ change has_fderiv_at_filter (f^[n] ∘ f) (f'^(n+1)) x L,
rw [pow_succ'],
refine has_fderiv_at_filter.comp x _ hf,
rw hx,
exact ihn.mono hL }
end
protected lemma has_fderiv_at.iterate {f : E → E} {f' : E →L[𝕜] E}
(hf : has_fderiv_at f f' x) (hx : f x = x) (n : ℕ) :
has_fderiv_at (f^[n]) (f'^n) x :=
begin
refine hf.iterate _ hx n,
convert hf.continuous_at,
exact hx.symm
end
protected lemma has_fderiv_within_at.iterate {f : E → E} {f' : E →L[𝕜] E}
(hf : has_fderiv_within_at f f' s x) (hx : f x = x) (hs : maps_to f s s) (n : ℕ) :
has_fderiv_within_at (f^[n]) (f'^n) s x :=
begin
refine hf.iterate _ hx n,
convert tendsto_inf.2 ⟨hf.continuous_within_at, _⟩,
exacts [hx.symm, (tendsto_principal_principal.2 hs).mono_left inf_le_right]
end
protected lemma has_strict_fderiv_at.iterate {f : E → E} {f' : E →L[𝕜] E}
(hf : has_strict_fderiv_at f f' x) (hx : f x = x) (n : ℕ) :
has_strict_fderiv_at (f^[n]) (f'^n) x :=
begin
induction n with n ihn,
{ exact has_strict_fderiv_at_id x },
{ change has_strict_fderiv_at (f^[n] ∘ f) (f'^(n+1)) x,
rw [pow_succ'],
refine has_strict_fderiv_at.comp x _ hf,
rwa hx }
end
protected lemma differentiable_at.iterate {f : E → E} (hf : differentiable_at 𝕜 f x)
(hx : f x = x) (n : ℕ) :
differentiable_at 𝕜 (f^[n]) x :=
exists.elim hf $ λ f' hf, (hf.iterate hx n).differentiable_at
protected lemma differentiable_within_at.iterate {f : E → E} (hf : differentiable_within_at 𝕜 f s x)
(hx : f x = x) (hs : maps_to f s s) (n : ℕ) :
differentiable_within_at 𝕜 (f^[n]) s x :=
exists.elim hf $ λ f' hf, (hf.iterate hx hs n).differentiable_within_at
end composition
section cartesian_product
/-! ### Derivative of the cartesian product of two functions -/
section prod
variables {f₂ : E → G} {f₂' : E →L[𝕜] G}
protected lemma has_strict_fderiv_at.prod
(hf₁ : has_strict_fderiv_at f₁ f₁' x) (hf₂ : has_strict_fderiv_at f₂ f₂' x) :
has_strict_fderiv_at (λx, (f₁ x, f₂ x)) (f₁'.prod f₂') x :=
hf₁.prod_left hf₂
lemma has_fderiv_at_filter.prod
(hf₁ : has_fderiv_at_filter f₁ f₁' x L) (hf₂ : has_fderiv_at_filter f₂ f₂' x L) :
has_fderiv_at_filter (λx, (f₁ x, f₂ x)) (f₁'.prod f₂') x L :=
hf₁.prod_left hf₂
lemma has_fderiv_within_at.prod
(hf₁ : has_fderiv_within_at f₁ f₁' s x) (hf₂ : has_fderiv_within_at f₂ f₂' s x) :
has_fderiv_within_at (λx, (f₁ x, f₂ x)) (f₁'.prod f₂') s x :=
hf₁.prod hf₂
lemma has_fderiv_at.prod (hf₁ : has_fderiv_at f₁ f₁' x) (hf₂ : has_fderiv_at f₂ f₂' x) :
has_fderiv_at (λx, (f₁ x, f₂ x)) (continuous_linear_map.prod f₁' f₂') x :=
hf₁.prod hf₂
lemma differentiable_within_at.prod
(hf₁ : differentiable_within_at 𝕜 f₁ s x) (hf₂ : differentiable_within_at 𝕜 f₂ s x) :
differentiable_within_at 𝕜 (λx:E, (f₁ x, f₂ x)) s x :=
(hf₁.has_fderiv_within_at.prod hf₂.has_fderiv_within_at).differentiable_within_at
@[simp]
lemma differentiable_at.prod (hf₁ : differentiable_at 𝕜 f₁ x) (hf₂ : differentiable_at 𝕜 f₂ x) :
differentiable_at 𝕜 (λx:E, (f₁ x, f₂ x)) x :=
(hf₁.has_fderiv_at.prod hf₂.has_fderiv_at).differentiable_at
lemma differentiable_on.prod (hf₁ : differentiable_on 𝕜 f₁ s) (hf₂ : differentiable_on 𝕜 f₂ s) :
differentiable_on 𝕜 (λx:E, (f₁ x, f₂ x)) s :=
λx hx, differentiable_within_at.prod (hf₁ x hx) (hf₂ x hx)
@[simp]
lemma differentiable.prod (hf₁ : differentiable 𝕜 f₁) (hf₂ : differentiable 𝕜 f₂) :
differentiable 𝕜 (λx:E, (f₁ x, f₂ x)) :=
λ x, differentiable_at.prod (hf₁ x) (hf₂ x)
lemma differentiable_at.fderiv_prod
(hf₁ : differentiable_at 𝕜 f₁ x) (hf₂ : differentiable_at 𝕜 f₂ x) :
fderiv 𝕜 (λx:E, (f₁ x, f₂ x)) x = (fderiv 𝕜 f₁ x).prod (fderiv 𝕜 f₂ x) :=
(hf₁.has_fderiv_at.prod hf₂.has_fderiv_at).fderiv
lemma differentiable_at.fderiv_within_prod
(hf₁ : differentiable_within_at 𝕜 f₁ s x) (hf₂ : differentiable_within_at 𝕜 f₂ s x)
(hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 (λx:E, (f₁ x, f₂ x)) s x =
(fderiv_within 𝕜 f₁ s x).prod (fderiv_within 𝕜 f₂ s x) :=
begin
apply has_fderiv_within_at.fderiv_within _ hxs,
exact has_fderiv_within_at.prod hf₁.has_fderiv_within_at hf₂.has_fderiv_within_at
end
end prod
section fst
variables {f₂ : E → F × G} {f₂' : E →L[𝕜] F × G} {p : E × F}
lemma has_strict_fderiv_at_fst : has_strict_fderiv_at prod.fst (fst 𝕜 E F) p :=
(fst 𝕜 E F).has_strict_fderiv_at
protected lemma has_strict_fderiv_at.fst (h : has_strict_fderiv_at f₂ f₂' x) :
has_strict_fderiv_at (λ x, (f₂ x).1) ((fst 𝕜 F G).comp f₂') x :=
has_strict_fderiv_at_fst.comp x h
lemma has_fderiv_at_filter_fst {L : filter (E × F)} :
has_fderiv_at_filter prod.fst (fst 𝕜 E F) p L :=
(fst 𝕜 E F).has_fderiv_at_filter
protected lemma has_fderiv_at_filter.fst (h : has_fderiv_at_filter f₂ f₂' x L) :
has_fderiv_at_filter (λ x, (f₂ x).1) ((fst 𝕜 F G).comp f₂') x L :=
has_fderiv_at_filter_fst.comp x h
lemma has_fderiv_at_fst : has_fderiv_at prod.fst (fst 𝕜 E F) p :=
has_fderiv_at_filter_fst
protected lemma has_fderiv_at.fst (h : has_fderiv_at f₂ f₂' x) :
has_fderiv_at (λ x, (f₂ x).1) ((fst 𝕜 F G).comp f₂') x :=
h.fst
lemma has_fderiv_within_at_fst {s : set (E × F)} :
has_fderiv_within_at prod.fst (fst 𝕜 E F) s p :=
has_fderiv_at_filter_fst
protected lemma has_fderiv_within_at.fst (h : has_fderiv_within_at f₂ f₂' s x) :
has_fderiv_within_at (λ x, (f₂ x).1) ((fst 𝕜 F G).comp f₂') s x :=
h.fst
lemma differentiable_at_fst : differentiable_at 𝕜 prod.fst p :=
has_fderiv_at_fst.differentiable_at
@[simp] protected lemma differentiable_at.fst (h : differentiable_at 𝕜 f₂ x) :
differentiable_at 𝕜 (λ x, (f₂ x).1) x :=
differentiable_at_fst.comp x h
lemma differentiable_fst : differentiable 𝕜 (prod.fst : E × F → E) :=
λ x, differentiable_at_fst
@[simp] protected lemma differentiable.fst (h : differentiable 𝕜 f₂) :
differentiable 𝕜 (λ x, (f₂ x).1) :=
differentiable_fst.comp h
lemma differentiable_within_at_fst {s : set (E × F)} : differentiable_within_at 𝕜 prod.fst s p :=
differentiable_at_fst.differentiable_within_at
protected lemma differentiable_within_at.fst (h : differentiable_within_at 𝕜 f₂ s x) :
differentiable_within_at 𝕜 (λ x, (f₂ x).1) s x :=
differentiable_at_fst.comp_differentiable_within_at x h
lemma differentiable_on_fst {s : set (E × F)} : differentiable_on 𝕜 prod.fst s :=
differentiable_fst.differentiable_on
protected lemma differentiable_on.fst (h : differentiable_on 𝕜 f₂ s) :
differentiable_on 𝕜 (λ x, (f₂ x).1) s :=
differentiable_fst.comp_differentiable_on h
lemma fderiv_fst : fderiv 𝕜 prod.fst p = fst 𝕜 E F := has_fderiv_at_fst.fderiv
lemma fderiv.fst (h : differentiable_at 𝕜 f₂ x) :
fderiv 𝕜 (λ x, (f₂ x).1) x = (fst 𝕜 F G).comp (fderiv 𝕜 f₂ x) :=
h.has_fderiv_at.fst.fderiv
lemma fderiv_within_fst {s : set (E × F)} (hs : unique_diff_within_at 𝕜 s p) :
fderiv_within 𝕜 prod.fst s p = fst 𝕜 E F :=
has_fderiv_within_at_fst.fderiv_within hs
lemma fderiv_within.fst (hs : unique_diff_within_at 𝕜 s x) (h : differentiable_within_at 𝕜 f₂ s x) :
fderiv_within 𝕜 (λ x, (f₂ x).1) s x = (fst 𝕜 F G).comp (fderiv_within 𝕜 f₂ s x) :=
h.has_fderiv_within_at.fst.fderiv_within hs
end fst
section snd
variables {f₂ : E → F × G} {f₂' : E →L[𝕜] F × G} {p : E × F}
lemma has_strict_fderiv_at_snd : has_strict_fderiv_at prod.snd (snd 𝕜 E F) p :=
(snd 𝕜 E F).has_strict_fderiv_at
protected lemma has_strict_fderiv_at.snd (h : has_strict_fderiv_at f₂ f₂' x) :
has_strict_fderiv_at (λ x, (f₂ x).2) ((snd 𝕜 F G).comp f₂') x :=
has_strict_fderiv_at_snd.comp x h
lemma has_fderiv_at_filter_snd {L : filter (E × F)} :
has_fderiv_at_filter prod.snd (snd 𝕜 E F) p L :=
(snd 𝕜 E F).has_fderiv_at_filter
protected lemma has_fderiv_at_filter.snd (h : has_fderiv_at_filter f₂ f₂' x L) :
has_fderiv_at_filter (λ x, (f₂ x).2) ((snd 𝕜 F G).comp f₂') x L :=
has_fderiv_at_filter_snd.comp x h
lemma has_fderiv_at_snd : has_fderiv_at prod.snd (snd 𝕜 E F) p :=
has_fderiv_at_filter_snd
protected lemma has_fderiv_at.snd (h : has_fderiv_at f₂ f₂' x) :
has_fderiv_at (λ x, (f₂ x).2) ((snd 𝕜 F G).comp f₂') x :=
h.snd
lemma has_fderiv_within_at_snd {s : set (E × F)} :
has_fderiv_within_at prod.snd (snd 𝕜 E F) s p :=
has_fderiv_at_filter_snd
protected lemma has_fderiv_within_at.snd (h : has_fderiv_within_at f₂ f₂' s x) :
has_fderiv_within_at (λ x, (f₂ x).2) ((snd 𝕜 F G).comp f₂') s x :=
h.snd
lemma differentiable_at_snd : differentiable_at 𝕜 prod.snd p :=
has_fderiv_at_snd.differentiable_at
@[simp] protected lemma differentiable_at.snd (h : differentiable_at 𝕜 f₂ x) :
differentiable_at 𝕜 (λ x, (f₂ x).2) x :=
differentiable_at_snd.comp x h
lemma differentiable_snd : differentiable 𝕜 (prod.snd : E × F → F) :=
λ x, differentiable_at_snd
@[simp] protected lemma differentiable.snd (h : differentiable 𝕜 f₂) :
differentiable 𝕜 (λ x, (f₂ x).2) :=
differentiable_snd.comp h
lemma differentiable_within_at_snd {s : set (E × F)} : differentiable_within_at 𝕜 prod.snd s p :=
differentiable_at_snd.differentiable_within_at
protected lemma differentiable_within_at.snd (h : differentiable_within_at 𝕜 f₂ s x) :
differentiable_within_at 𝕜 (λ x, (f₂ x).2) s x :=
differentiable_at_snd.comp_differentiable_within_at x h
lemma differentiable_on_snd {s : set (E × F)} : differentiable_on 𝕜 prod.snd s :=
differentiable_snd.differentiable_on
protected lemma differentiable_on.snd (h : differentiable_on 𝕜 f₂ s) :
differentiable_on 𝕜 (λ x, (f₂ x).2) s :=
differentiable_snd.comp_differentiable_on h
lemma fderiv_snd : fderiv 𝕜 prod.snd p = snd 𝕜 E F := has_fderiv_at_snd.fderiv
lemma fderiv.snd (h : differentiable_at 𝕜 f₂ x) :
fderiv 𝕜 (λ x, (f₂ x).2) x = (snd 𝕜 F G).comp (fderiv 𝕜 f₂ x) :=
h.has_fderiv_at.snd.fderiv
lemma fderiv_within_snd {s : set (E × F)} (hs : unique_diff_within_at 𝕜 s p) :
fderiv_within 𝕜 prod.snd s p = snd 𝕜 E F :=
has_fderiv_within_at_snd.fderiv_within hs
lemma fderiv_within.snd (hs : unique_diff_within_at 𝕜 s x) (h : differentiable_within_at 𝕜 f₂ s x) :
fderiv_within 𝕜 (λ x, (f₂ x).2) s x = (snd 𝕜 F G).comp (fderiv_within 𝕜 f₂ s x) :=
h.has_fderiv_within_at.snd.fderiv_within hs
end snd
section prod_map
variables {f₂ : G → G'} {f₂' : G →L[𝕜] G'} {y : G} (p : E × G)
-- TODO (Lean 3.8): use `prod.map f f₂``
protected theorem has_strict_fderiv_at.prod_map (hf : has_strict_fderiv_at f f' p.1)
(hf₂ : has_strict_fderiv_at f₂ f₂' p.2) :
has_strict_fderiv_at (λ p : E × G, (f p.1, f₂ p.2)) (f'.prod_map f₂') p :=
(hf.comp p has_strict_fderiv_at_fst).prod (hf₂.comp p has_strict_fderiv_at_snd)
protected theorem has_fderiv_at.prod_map (hf : has_fderiv_at f f' p.1)
(hf₂ : has_fderiv_at f₂ f₂' p.2) :
has_fderiv_at (λ p : E × G, (f p.1, f₂ p.2)) (f'.prod_map f₂') p :=
(hf.comp p has_fderiv_at_fst).prod (hf₂.comp p has_fderiv_at_snd)
@[simp] protected theorem differentiable_at.prod_map (hf : differentiable_at 𝕜 f p.1)
(hf₂ : differentiable_at 𝕜 f₂ p.2) :
differentiable_at 𝕜 (λ p : E × G, (f p.1, f₂ p.2)) p :=
(hf.comp p differentiable_at_fst).prod (hf₂.comp p differentiable_at_snd)
end prod_map
end cartesian_product
section const_smul
/-! ### Derivative of a function multiplied by a constant -/
theorem has_strict_fderiv_at.const_smul (h : has_strict_fderiv_at f f' x) (c : 𝕜) :
has_strict_fderiv_at (λ x, c • f x) (c • f') x :=
(c • (1 : F →L[𝕜] F)).has_strict_fderiv_at.comp x h
theorem has_fderiv_at_filter.const_smul (h : has_fderiv_at_filter f f' x L) (c : 𝕜) :
has_fderiv_at_filter (λ x, c • f x) (c • f') x L :=
(c • (1 : F →L[𝕜] F)).has_fderiv_at_filter.comp x h
theorem has_fderiv_within_at.const_smul (h : has_fderiv_within_at f f' s x) (c : 𝕜) :
has_fderiv_within_at (λ x, c • f x) (c • f') s x :=
h.const_smul c
theorem has_fderiv_at.const_smul (h : has_fderiv_at f f' x) (c : 𝕜) :
has_fderiv_at (λ x, c • f x) (c • f') x :=
h.const_smul c
lemma differentiable_within_at.const_smul (h : differentiable_within_at 𝕜 f s x) (c : 𝕜) :
differentiable_within_at 𝕜 (λy, c • f y) s x :=
(h.has_fderiv_within_at.const_smul c).differentiable_within_at
lemma differentiable_at.const_smul (h : differentiable_at 𝕜 f x) (c : 𝕜) :
differentiable_at 𝕜 (λy, c • f y) x :=
(h.has_fderiv_at.const_smul c).differentiable_at
lemma differentiable_on.const_smul (h : differentiable_on 𝕜 f s) (c : 𝕜) :
differentiable_on 𝕜 (λy, c • f y) s :=
λx hx, (h x hx).const_smul c
lemma differentiable.const_smul (h : differentiable 𝕜 f) (c : 𝕜) :
differentiable 𝕜 (λy, c • f y) :=
λx, (h x).const_smul c
lemma fderiv_within_const_smul (hxs : unique_diff_within_at 𝕜 s x)
(h : differentiable_within_at 𝕜 f s x) (c : 𝕜) :
fderiv_within 𝕜 (λy, c • f y) s x = c • fderiv_within 𝕜 f s x :=
(h.has_fderiv_within_at.const_smul c).fderiv_within hxs
lemma fderiv_const_smul (h : differentiable_at 𝕜 f x) (c : 𝕜) :
fderiv 𝕜 (λy, c • f y) x = c • fderiv 𝕜 f x :=
(h.has_fderiv_at.const_smul c).fderiv
end const_smul
section add
/-! ### Derivative of the sum of two functions -/
theorem has_strict_fderiv_at.add (hf : has_strict_fderiv_at f f' x)
(hg : has_strict_fderiv_at g g' x) :
has_strict_fderiv_at (λ y, f y + g y) (f' + g') x :=
(hf.add hg).congr_left $ λ y, by simp; abel
theorem has_fderiv_at_filter.add
(hf : has_fderiv_at_filter f f' x L) (hg : has_fderiv_at_filter g g' x L) :
has_fderiv_at_filter (λ y, f y + g y) (f' + g') x L :=
(hf.add hg).congr_left $ λ _, by simp; abel
theorem has_fderiv_within_at.add
(hf : has_fderiv_within_at f f' s x) (hg : has_fderiv_within_at g g' s x) :
has_fderiv_within_at (λ y, f y + g y) (f' + g') s x :=
hf.add hg
theorem has_fderiv_at.add
(hf : has_fderiv_at f f' x) (hg : has_fderiv_at g g' x) :
has_fderiv_at (λ x, f x + g x) (f' + g') x :=
hf.add hg
lemma differentiable_within_at.add
(hf : differentiable_within_at 𝕜 f s x) (hg : differentiable_within_at 𝕜 g s x) :
differentiable_within_at 𝕜 (λ y, f y + g y) s x :=
(hf.has_fderiv_within_at.add hg.has_fderiv_within_at).differentiable_within_at
@[simp] lemma differentiable_at.add
(hf : differentiable_at 𝕜 f x) (hg : differentiable_at 𝕜 g x) :
differentiable_at 𝕜 (λ y, f y + g y) x :=
(hf.has_fderiv_at.add hg.has_fderiv_at).differentiable_at
lemma differentiable_on.add
(hf : differentiable_on 𝕜 f s) (hg : differentiable_on 𝕜 g s) :
differentiable_on 𝕜 (λy, f y + g y) s :=
λx hx, (hf x hx).add (hg x hx)
@[simp] lemma differentiable.add
(hf : differentiable 𝕜 f) (hg : differentiable 𝕜 g) :
differentiable 𝕜 (λy, f y + g y) :=
λx, (hf x).add (hg x)
lemma fderiv_within_add (hxs : unique_diff_within_at 𝕜 s x)
(hf : differentiable_within_at 𝕜 f s x) (hg : differentiable_within_at 𝕜 g s x) :
fderiv_within 𝕜 (λy, f y + g y) s x = fderiv_within 𝕜 f s x + fderiv_within 𝕜 g s x :=
(hf.has_fderiv_within_at.add hg.has_fderiv_within_at).fderiv_within hxs
lemma fderiv_add
(hf : differentiable_at 𝕜 f x) (hg : differentiable_at 𝕜 g x) :
fderiv 𝕜 (λy, f y + g y) x = fderiv 𝕜 f x + fderiv 𝕜 g x :=
(hf.has_fderiv_at.add hg.has_fderiv_at).fderiv
theorem has_strict_fderiv_at.add_const (hf : has_strict_fderiv_at f f' x) (c : F) :
has_strict_fderiv_at (λ y, f y + c) f' x :=
add_zero f' ▸ hf.add (has_strict_fderiv_at_const _ _)
theorem has_fderiv_at_filter.add_const
(hf : has_fderiv_at_filter f f' x L) (c : F) :
has_fderiv_at_filter (λ y, f y + c) f' x L :=
add_zero f' ▸ hf.add (has_fderiv_at_filter_const _ _ _)
theorem has_fderiv_within_at.add_const
(hf : has_fderiv_within_at f f' s x) (c : F) :
has_fderiv_within_at (λ y, f y + c) f' s x :=
hf.add_const c
theorem has_fderiv_at.add_const
(hf : has_fderiv_at f f' x) (c : F):
has_fderiv_at (λ x, f x + c) f' x :=
hf.add_const c
lemma differentiable_within_at.add_const
(hf : differentiable_within_at 𝕜 f s x) (c : F) :
differentiable_within_at 𝕜 (λ y, f y + c) s x :=
(hf.has_fderiv_within_at.add_const c).differentiable_within_at
lemma differentiable_at.add_const
(hf : differentiable_at 𝕜 f x) (c : F) :
differentiable_at 𝕜 (λ y, f y + c) x :=
(hf.has_fderiv_at.add_const c).differentiable_at
lemma differentiable_on.add_const
(hf : differentiable_on 𝕜 f s) (c : F) :
differentiable_on 𝕜 (λy, f y + c) s :=
λx hx, (hf x hx).add_const c
lemma differentiable.add_const
(hf : differentiable 𝕜 f) (c : F) :
differentiable 𝕜 (λy, f y + c) :=
λx, (hf x).add_const c
lemma fderiv_within_add_const (hxs : unique_diff_within_at 𝕜 s x)
(hf : differentiable_within_at 𝕜 f s x) (c : F) :
fderiv_within 𝕜 (λy, f y + c) s x = fderiv_within 𝕜 f s x :=
(hf.has_fderiv_within_at.add_const c).fderiv_within hxs
lemma fderiv_add_const
(hf : differentiable_at 𝕜 f x) (c : F) :
fderiv 𝕜 (λy, f y + c) x = fderiv 𝕜 f x :=
(hf.has_fderiv_at.add_const c).fderiv
theorem has_strict_fderiv_at.const_add (hf : has_strict_fderiv_at f f' x) (c : F) :
has_strict_fderiv_at (λ y, c + f y) f' x :=
zero_add f' ▸ (has_strict_fderiv_at_const _ _).add hf
theorem has_fderiv_at_filter.const_add
(hf : has_fderiv_at_filter f f' x L) (c : F) :
has_fderiv_at_filter (λ y, c + f y) f' x L :=
zero_add f' ▸ (has_fderiv_at_filter_const _ _ _).add hf
theorem has_fderiv_within_at.const_add
(hf : has_fderiv_within_at f f' s x) (c : F) :
has_fderiv_within_at (λ y, c + f y) f' s x :=
hf.const_add c
theorem has_fderiv_at.const_add
(hf : has_fderiv_at f f' x) (c : F):
has_fderiv_at (λ x, c + f x) f' x :=
hf.const_add c
lemma differentiable_within_at.const_add
(hf : differentiable_within_at 𝕜 f s x) (c : F) :
differentiable_within_at 𝕜 (λ y, c + f y) s x :=
(hf.has_fderiv_within_at.const_add c).differentiable_within_at
lemma differentiable_at.const_add
(hf : differentiable_at 𝕜 f x) (c : F) :
differentiable_at 𝕜 (λ y, c + f y) x :=
(hf.has_fderiv_at.const_add c).differentiable_at
lemma differentiable_on.const_add
(hf : differentiable_on 𝕜 f s) (c : F) :
differentiable_on 𝕜 (λy, c + f y) s :=
λx hx, (hf x hx).const_add c
lemma differentiable.const_add
(hf : differentiable 𝕜 f) (c : F) :
differentiable 𝕜 (λy, c + f y) :=
λx, (hf x).const_add c
lemma fderiv_within_const_add (hxs : unique_diff_within_at 𝕜 s x)
(hf : differentiable_within_at 𝕜 f s x) (c : F) :
fderiv_within 𝕜 (λy, c + f y) s x = fderiv_within 𝕜 f s x :=
(hf.has_fderiv_within_at.const_add c).fderiv_within hxs
lemma fderiv_const_add
(hf : differentiable_at 𝕜 f x) (c : F) :
fderiv 𝕜 (λy, c + f y) x = fderiv 𝕜 f x :=
(hf.has_fderiv_at.const_add c).fderiv
end add
section sum
/-! ### Derivative of a finite sum of functions -/
open_locale big_operators
variables {ι : Type*} {u : finset ι} {A : ι → (E → F)} {A' : ι → (E →L[𝕜] F)}
theorem has_strict_fderiv_at.sum (h : ∀ i ∈ u, has_strict_fderiv_at (A i) (A' i) x) :
has_strict_fderiv_at (λ y, ∑ i in u, A i y) (∑ i in u, A' i) x :=
begin
dsimp [has_strict_fderiv_at] at *,
convert is_o.sum h,
simp [finset.sum_sub_distrib, continuous_linear_map.sum_apply]
end
theorem has_fderiv_at_filter.sum (h : ∀ i ∈ u, has_fderiv_at_filter (A i) (A' i) x L) :
has_fderiv_at_filter (λ y, ∑ i in u, A i y) (∑ i in u, A' i) x L :=
begin
dsimp [has_fderiv_at_filter] at *,
convert is_o.sum h,
simp [continuous_linear_map.sum_apply]
end
theorem has_fderiv_within_at.sum (h : ∀ i ∈ u, has_fderiv_within_at (A i) (A' i) s x) :
has_fderiv_within_at (λ y, ∑ i in u, A i y) (∑ i in u, A' i) s x :=
has_fderiv_at_filter.sum h
theorem has_fderiv_at.sum (h : ∀ i ∈ u, has_fderiv_at (A i) (A' i) x) :
has_fderiv_at (λ y, ∑ i in u, A i y) (∑ i in u, A' i) x :=
has_fderiv_at_filter.sum h
theorem differentiable_within_at.sum (h : ∀ i ∈ u, differentiable_within_at 𝕜 (A i) s x) :
differentiable_within_at 𝕜 (λ y, ∑ i in u, A i y) s x :=
has_fderiv_within_at.differentiable_within_at $ has_fderiv_within_at.sum $
λ i hi, (h i hi).has_fderiv_within_at
@[simp] theorem differentiable_at.sum (h : ∀ i ∈ u, differentiable_at 𝕜 (A i) x) :
differentiable_at 𝕜 (λ y, ∑ i in u, A i y) x :=
has_fderiv_at.differentiable_at $ has_fderiv_at.sum $ λ i hi, (h i hi).has_fderiv_at
theorem differentiable_on.sum (h : ∀ i ∈ u, differentiable_on 𝕜 (A i) s) :
differentiable_on 𝕜 (λ y, ∑ i in u, A i y) s :=
λ x hx, differentiable_within_at.sum $ λ i hi, h i hi x hx
@[simp] theorem differentiable.sum (h : ∀ i ∈ u, differentiable 𝕜 (A i)) :
differentiable 𝕜 (λ y, ∑ i in u, A i y) :=
λ x, differentiable_at.sum $ λ i hi, h i hi x
theorem fderiv_within_sum (hxs : unique_diff_within_at 𝕜 s x)
(h : ∀ i ∈ u, differentiable_within_at 𝕜 (A i) s x) :
fderiv_within 𝕜 (λ y, ∑ i in u, A i y) s x = (∑ i in u, fderiv_within 𝕜 (A i) s x) :=
(has_fderiv_within_at.sum (λ i hi, (h i hi).has_fderiv_within_at)).fderiv_within hxs
theorem fderiv_sum (h : ∀ i ∈ u, differentiable_at 𝕜 (A i) x) :
fderiv 𝕜 (λ y, ∑ i in u, A i y) x = (∑ i in u, fderiv 𝕜 (A i) x) :=
(has_fderiv_at.sum (λ i hi, (h i hi).has_fderiv_at)).fderiv
end sum
section neg
/-! ### Derivative of the negative of a function -/
theorem has_strict_fderiv_at.neg (h : has_strict_fderiv_at f f' x) :
has_strict_fderiv_at (λ x, -f x) (-f') x :=
(-1 : F →L[𝕜] F).has_strict_fderiv_at.comp x h
theorem has_fderiv_at_filter.neg (h : has_fderiv_at_filter f f' x L) :
has_fderiv_at_filter (λ x, -f x) (-f') x L :=
(-1 : F →L[𝕜] F).has_fderiv_at_filter.comp x h
theorem has_fderiv_within_at.neg (h : has_fderiv_within_at f f' s x) :
has_fderiv_within_at (λ x, -f x) (-f') s x :=
h.neg
theorem has_fderiv_at.neg (h : has_fderiv_at f f' x) :
has_fderiv_at (λ x, -f x) (-f') x :=
h.neg
lemma differentiable_within_at.neg (h : differentiable_within_at 𝕜 f s x) :
differentiable_within_at 𝕜 (λy, -f y) s x :=
h.has_fderiv_within_at.neg.differentiable_within_at
@[simp] lemma differentiable_at.neg (h : differentiable_at 𝕜 f x) :
differentiable_at 𝕜 (λy, -f y) x :=
h.has_fderiv_at.neg.differentiable_at
lemma differentiable_on.neg (h : differentiable_on 𝕜 f s) :
differentiable_on 𝕜 (λy, -f y) s :=
λx hx, (h x hx).neg
@[simp] lemma differentiable.neg (h : differentiable 𝕜 f) :
differentiable 𝕜 (λy, -f y) :=
λx, (h x).neg
lemma fderiv_within_neg (hxs : unique_diff_within_at 𝕜 s x)
(h : differentiable_within_at 𝕜 f s x) :
fderiv_within 𝕜 (λy, -f y) s x = - fderiv_within 𝕜 f s x :=
h.has_fderiv_within_at.neg.fderiv_within hxs
lemma fderiv_neg (h : differentiable_at 𝕜 f x) :
fderiv 𝕜 (λy, -f y) x = - fderiv 𝕜 f x :=
h.has_fderiv_at.neg.fderiv
end neg
section sub
/-! ### Derivative of the difference of two functions -/
theorem has_strict_fderiv_at.sub
(hf : has_strict_fderiv_at f f' x) (hg : has_strict_fderiv_at g g' x) :
has_strict_fderiv_at (λ x, f x - g x) (f' - g') x :=
hf.add hg.neg
theorem has_fderiv_at_filter.sub
(hf : has_fderiv_at_filter f f' x L) (hg : has_fderiv_at_filter g g' x L) :
has_fderiv_at_filter (λ x, f x - g x) (f' - g') x L :=
hf.add hg.neg
theorem has_fderiv_within_at.sub
(hf : has_fderiv_within_at f f' s x) (hg : has_fderiv_within_at g g' s x) :
has_fderiv_within_at (λ x, f x - g x) (f' - g') s x :=
hf.sub hg
theorem has_fderiv_at.sub
(hf : has_fderiv_at f f' x) (hg : has_fderiv_at g g' x) :
has_fderiv_at (λ x, f x - g x) (f' - g') x :=
hf.sub hg
lemma differentiable_within_at.sub
(hf : differentiable_within_at 𝕜 f s x) (hg : differentiable_within_at 𝕜 g s x) :
differentiable_within_at 𝕜 (λ y, f y - g y) s x :=
(hf.has_fderiv_within_at.sub hg.has_fderiv_within_at).differentiable_within_at
@[simp] lemma differentiable_at.sub
(hf : differentiable_at 𝕜 f x) (hg : differentiable_at 𝕜 g x) :
differentiable_at 𝕜 (λ y, f y - g y) x :=
(hf.has_fderiv_at.sub hg.has_fderiv_at).differentiable_at
lemma differentiable_on.sub
(hf : differentiable_on 𝕜 f s) (hg : differentiable_on 𝕜 g s) :
differentiable_on 𝕜 (λy, f y - g y) s :=
λx hx, (hf x hx).sub (hg x hx)
@[simp] lemma differentiable.sub
(hf : differentiable 𝕜 f) (hg : differentiable 𝕜 g) :
differentiable 𝕜 (λy, f y - g y) :=
λx, (hf x).sub (hg x)
lemma fderiv_within_sub (hxs : unique_diff_within_at 𝕜 s x)
(hf : differentiable_within_at 𝕜 f s x) (hg : differentiable_within_at 𝕜 g s x) :
fderiv_within 𝕜 (λy, f y - g y) s x = fderiv_within 𝕜 f s x - fderiv_within 𝕜 g s x :=
(hf.has_fderiv_within_at.sub hg.has_fderiv_within_at).fderiv_within hxs
lemma fderiv_sub
(hf : differentiable_at 𝕜 f x) (hg : differentiable_at 𝕜 g x) :
fderiv 𝕜 (λy, f y - g y) x = fderiv 𝕜 f x - fderiv 𝕜 g x :=
(hf.has_fderiv_at.sub hg.has_fderiv_at).fderiv
theorem has_strict_fderiv_at.sub_const
(hf : has_strict_fderiv_at f f' x) (c : F) :
has_strict_fderiv_at (λ x, f x - c) f' x :=
hf.add_const (-c)
theorem has_fderiv_at_filter.sub_const
(hf : has_fderiv_at_filter f f' x L) (c : F) :
has_fderiv_at_filter (λ x, f x - c) f' x L :=
hf.add_const (-c)
theorem has_fderiv_within_at.sub_const
(hf : has_fderiv_within_at f f' s x) (c : F) :
has_fderiv_within_at (λ x, f x - c) f' s x :=
hf.sub_const c
theorem has_fderiv_at.sub_const
(hf : has_fderiv_at f f' x) (c : F) :
has_fderiv_at (λ x, f x - c) f' x :=
hf.sub_const c
lemma differentiable_within_at.sub_const
(hf : differentiable_within_at 𝕜 f s x) (c : F) :
differentiable_within_at 𝕜 (λ y, f y - c) s x :=
(hf.has_fderiv_within_at.sub_const c).differentiable_within_at
lemma differentiable_at.sub_const
(hf : differentiable_at 𝕜 f x) (c : F) :
differentiable_at 𝕜 (λ y, f y - c) x :=
(hf.has_fderiv_at.sub_const c).differentiable_at
lemma differentiable_on.sub_const
(hf : differentiable_on 𝕜 f s) (c : F) :
differentiable_on 𝕜 (λy, f y - c) s :=
λx hx, (hf x hx).sub_const c
lemma differentiable.sub_const
(hf : differentiable 𝕜 f) (c : F) :
differentiable 𝕜 (λy, f y - c) :=
λx, (hf x).sub_const c
lemma fderiv_within_sub_const (hxs : unique_diff_within_at 𝕜 s x)
(hf : differentiable_within_at 𝕜 f s x) (c : F) :
fderiv_within 𝕜 (λy, f y - c) s x = fderiv_within 𝕜 f s x :=
(hf.has_fderiv_within_at.sub_const c).fderiv_within hxs
lemma fderiv_sub_const
(hf : differentiable_at 𝕜 f x) (c : F) :
fderiv 𝕜 (λy, f y - c) x = fderiv 𝕜 f x :=
(hf.has_fderiv_at.sub_const c).fderiv
theorem has_strict_fderiv_at.const_sub
(hf : has_strict_fderiv_at f f' x) (c : F) :
has_strict_fderiv_at (λ x, c - f x) (-f') x :=
hf.neg.const_add c
theorem has_fderiv_at_filter.const_sub
(hf : has_fderiv_at_filter f f' x L) (c : F) :
has_fderiv_at_filter (λ x, c - f x) (-f') x L :=
hf.neg.const_add c
theorem has_fderiv_within_at.const_sub
(hf : has_fderiv_within_at f f' s x) (c : F) :
has_fderiv_within_at (λ x, c - f x) (-f') s x :=
hf.const_sub c
theorem has_fderiv_at.const_sub
(hf : has_fderiv_at f f' x) (c : F) :
has_fderiv_at (λ x, c - f x) (-f') x :=
hf.const_sub c
lemma differentiable_within_at.const_sub
(hf : differentiable_within_at 𝕜 f s x) (c : F) :
differentiable_within_at 𝕜 (λ y, c - f y) s x :=
(hf.has_fderiv_within_at.const_sub c).differentiable_within_at
lemma differentiable_at.const_sub
(hf : differentiable_at 𝕜 f x) (c : F) :
differentiable_at 𝕜 (λ y, c - f y) x :=
(hf.has_fderiv_at.const_sub c).differentiable_at
lemma differentiable_on.const_sub
(hf : differentiable_on 𝕜 f s) (c : F) :
differentiable_on 𝕜 (λy, c - f y) s :=
λx hx, (hf x hx).const_sub c
lemma differentiable.const_sub
(hf : differentiable 𝕜 f) (c : F) :
differentiable 𝕜 (λy, c - f y) :=
λx, (hf x).const_sub c
lemma fderiv_within_const_sub (hxs : unique_diff_within_at 𝕜 s x)
(hf : differentiable_within_at 𝕜 f s x) (c : F) :
fderiv_within 𝕜 (λy, c - f y) s x = -fderiv_within 𝕜 f s x :=
(hf.has_fderiv_within_at.const_sub c).fderiv_within hxs
lemma fderiv_const_sub
(hf : differentiable_at 𝕜 f x) (c : F) :
fderiv 𝕜 (λy, c - f y) x = -fderiv 𝕜 f x :=
(hf.has_fderiv_at.const_sub c).fderiv
end sub
section bilinear_map
/-! ### Derivative of a bounded bilinear map -/
variables {b : E × F → G} {u : set (E × F) }
open normed_field
lemma is_bounded_bilinear_map.has_strict_fderiv_at (h : is_bounded_bilinear_map 𝕜 b) (p : E × F) :
has_strict_fderiv_at b (h.deriv p) p :=
begin
rw has_strict_fderiv_at,
set T := (E × F) × (E × F),
have : is_o (λ q : T, b (q.1 - q.2)) (λ q : T, ∥q.1 - q.2∥ * 1) (𝓝 (p, p)),
{ refine (h.is_O'.comp_tendsto le_top).trans_is_o _,
simp only [(∘)],
refine (is_O_refl (λ q : T, ∥q.1 - q.2∥) _).mul_is_o (is_o.norm_left $ (is_o_one_iff _).2 _),
rw [← sub_self p],
exact continuous_at_fst.sub continuous_at_snd },
simp only [mul_one, is_o_norm_right] at this,
refine (is_o.congr_of_sub _).1 this, clear this,
convert_to is_o (λ q : T, h.deriv (p - q.2) (q.1 - q.2)) (λ q : T, q.1 - q.2) (𝓝 (p, p)),
{ ext ⟨⟨x₁, y₁⟩, ⟨x₂, y₂⟩⟩, rcases p with ⟨x, y⟩,
simp only [is_bounded_bilinear_map_deriv_coe, prod.mk_sub_mk, h.map_sub_left, h.map_sub_right],
abel },
have : is_o (λ q : T, p - q.2) (λ q, (1:ℝ)) (𝓝 (p, p)),
from (is_o_one_iff _).2 (sub_self p ▸ tendsto_const_nhds.sub continuous_at_snd),
apply is_bounded_bilinear_map_apply.is_O_comp.trans_is_o,
refine is_o.trans_is_O _ (is_O_const_mul_self 1 _ _).of_norm_right,
refine is_o.mul_is_O _ (is_O_refl _ _),
exact (((h.is_bounded_linear_map_deriv.is_O_id ⊤).comp_tendsto le_top : _).trans_is_o this).norm_left
end
lemma is_bounded_bilinear_map.has_fderiv_at (h : is_bounded_bilinear_map 𝕜 b) (p : E × F) :
has_fderiv_at b (h.deriv p) p :=
(h.has_strict_fderiv_at p).has_fderiv_at
lemma is_bounded_bilinear_map.has_fderiv_within_at (h : is_bounded_bilinear_map 𝕜 b) (p : E × F) :
has_fderiv_within_at b (h.deriv p) u p :=
(h.has_fderiv_at p).has_fderiv_within_at
lemma is_bounded_bilinear_map.differentiable_at (h : is_bounded_bilinear_map 𝕜 b) (p : E × F) :
differentiable_at 𝕜 b p :=
(h.has_fderiv_at p).differentiable_at
lemma is_bounded_bilinear_map.differentiable_within_at (h : is_bounded_bilinear_map 𝕜 b)
(p : E × F) :
differentiable_within_at 𝕜 b u p :=
(h.differentiable_at p).differentiable_within_at
lemma is_bounded_bilinear_map.fderiv (h : is_bounded_bilinear_map 𝕜 b) (p : E × F) :
fderiv 𝕜 b p = h.deriv p :=
has_fderiv_at.fderiv (h.has_fderiv_at p)
lemma is_bounded_bilinear_map.fderiv_within (h : is_bounded_bilinear_map 𝕜 b) (p : E × F)
(hxs : unique_diff_within_at 𝕜 u p) : fderiv_within 𝕜 b u p = h.deriv p :=
begin
rw differentiable_at.fderiv_within (h.differentiable_at p) hxs,
exact h.fderiv p
end
lemma is_bounded_bilinear_map.differentiable (h : is_bounded_bilinear_map 𝕜 b) :
differentiable 𝕜 b :=
λx, h.differentiable_at x
lemma is_bounded_bilinear_map.differentiable_on (h : is_bounded_bilinear_map 𝕜 b) :
differentiable_on 𝕜 b u :=
h.differentiable.differentiable_on
lemma is_bounded_bilinear_map.continuous (h : is_bounded_bilinear_map 𝕜 b) :
continuous b :=
h.differentiable.continuous
lemma is_bounded_bilinear_map.continuous_left (h : is_bounded_bilinear_map 𝕜 b) {f : F} :
continuous (λe, b (e, f)) :=
h.continuous.comp (continuous_id.prod_mk continuous_const)
lemma is_bounded_bilinear_map.continuous_right (h : is_bounded_bilinear_map 𝕜 b) {e : E} :
continuous (λf, b (e, f)) :=
h.continuous.comp (continuous_const.prod_mk continuous_id)
end bilinear_map
namespace continuous_linear_equiv
/-!
### The set of continuous linear equivalences between two Banach spaces is open
In this section we establish that the set of continuous linear equivalences between two Banach
spaces is an open subset of the space of linear maps between them. These facts are placed here
because the proof uses `is_bounded_bilinear_map.continuous`, proved just above as a consequence
of its differentiability.
-/
protected lemma is_open [complete_space E] : is_open (range (coe : (E ≃L[𝕜] F) → (E →L[𝕜] F))) :=
begin
rw [is_open_iff_mem_nhds, forall_range_iff],
refine λ e, mem_nhds_sets _ (mem_range_self _),
let O : (E →L[𝕜] F) → (E →L[𝕜] E) := λ f, (e.symm : F →L[𝕜] E).comp f,
cases subsingleton_or_nontrivial E with _i _i; resetI,
{ exact is_open_discrete _ },
have h_O : continuous O,
{ have h_e_symm : continuous (λ (x : E →L[𝕜] F), (e.symm : F →L[𝕜] E)) := continuous_const,
exact is_bounded_bilinear_map_comp.continuous.comp (continuous_id.prod_mk h_e_symm) },
convert units.is_open.preimage h_O using 1,
ext f',
split,
{ rintros ⟨e', rfl⟩,
let w : units (E →L[𝕜] E) := continuous_linear_equiv.to_unit (e'.trans e.symm),
exact ⟨w, rfl⟩ },
{ rintros ⟨w, hw⟩,
let e' : E ≃L[𝕜] E := continuous_linear_equiv.of_unit w,
use e'.trans e,
ext x,
have he'w : e' x = w x := rfl,
simp [hw, he'w] }
end
protected lemma nhds [complete_space E] (e : E ≃L[𝕜] F) :
(range (coe : (E ≃L[𝕜] F) → (E →L[𝕜] F))) ∈ 𝓝 (e : E →L[𝕜] F) :=
mem_nhds_sets continuous_linear_equiv.is_open (by simp)
end continuous_linear_equiv
section smul
/-! ### Derivative of the product of a scalar-valued function and a vector-valued function -/
variables {c : E → 𝕜} {c' : E →L[𝕜] 𝕜}
theorem has_strict_fderiv_at.smul (hc : has_strict_fderiv_at c c' x)
(hf : has_strict_fderiv_at f f' x) :
has_strict_fderiv_at (λ y, c y • f y) (c x • f' + c'.smul_right (f x)) x :=
(is_bounded_bilinear_map_smul.has_strict_fderiv_at (c x, f x)).comp x $
hc.prod hf
theorem has_fderiv_within_at.smul
(hc : has_fderiv_within_at c c' s x) (hf : has_fderiv_within_at f f' s x) :
has_fderiv_within_at (λ y, c y • f y) (c x • f' + c'.smul_right (f x)) s x :=
(is_bounded_bilinear_map_smul.has_fderiv_at (c x, f x)).comp_has_fderiv_within_at x $
hc.prod hf
theorem has_fderiv_at.smul (hc : has_fderiv_at c c' x) (hf : has_fderiv_at f f' x) :
has_fderiv_at (λ y, c y • f y) (c x • f' + c'.smul_right (f x)) x :=
(is_bounded_bilinear_map_smul.has_fderiv_at (c x, f x)).comp x $
hc.prod hf
lemma differentiable_within_at.smul
(hc : differentiable_within_at 𝕜 c s x) (hf : differentiable_within_at 𝕜 f s x) :
differentiable_within_at 𝕜 (λ y, c y • f y) s x :=
(hc.has_fderiv_within_at.smul hf.has_fderiv_within_at).differentiable_within_at
@[simp] lemma differentiable_at.smul (hc : differentiable_at 𝕜 c x) (hf : differentiable_at 𝕜 f x) :
differentiable_at 𝕜 (λ y, c y • f y) x :=
(hc.has_fderiv_at.smul hf.has_fderiv_at).differentiable_at
lemma differentiable_on.smul (hc : differentiable_on 𝕜 c s) (hf : differentiable_on 𝕜 f s) :
differentiable_on 𝕜 (λ y, c y • f y) s :=
λx hx, (hc x hx).smul (hf x hx)
@[simp] lemma differentiable.smul (hc : differentiable 𝕜 c) (hf : differentiable 𝕜 f) :
differentiable 𝕜 (λ y, c y • f y) :=
λx, (hc x).smul (hf x)
lemma fderiv_within_smul (hxs : unique_diff_within_at 𝕜 s x)
(hc : differentiable_within_at 𝕜 c s x) (hf : differentiable_within_at 𝕜 f s x) :
fderiv_within 𝕜 (λ y, c y • f y) s x =
c x • fderiv_within 𝕜 f s x + (fderiv_within 𝕜 c s x).smul_right (f x) :=
(hc.has_fderiv_within_at.smul hf.has_fderiv_within_at).fderiv_within hxs
lemma fderiv_smul (hc : differentiable_at 𝕜 c x) (hf : differentiable_at 𝕜 f x) :
fderiv 𝕜 (λ y, c y • f y) x =
c x • fderiv 𝕜 f x + (fderiv 𝕜 c x).smul_right (f x) :=
(hc.has_fderiv_at.smul hf.has_fderiv_at).fderiv
theorem has_strict_fderiv_at.smul_const (hc : has_strict_fderiv_at c c' x) (f : F) :
has_strict_fderiv_at (λ y, c y • f) (c'.smul_right f) x :=
by simpa only [smul_zero, zero_add] using hc.smul (has_strict_fderiv_at_const f x)
theorem has_fderiv_within_at.smul_const (hc : has_fderiv_within_at c c' s x) (f : F) :
has_fderiv_within_at (λ y, c y • f) (c'.smul_right f) s x :=
by simpa only [smul_zero, zero_add] using hc.smul (has_fderiv_within_at_const f x s)
theorem has_fderiv_at.smul_const (hc : has_fderiv_at c c' x) (f : F) :
has_fderiv_at (λ y, c y • f) (c'.smul_right f) x :=
by simpa only [smul_zero, zero_add] using hc.smul (has_fderiv_at_const f x)
lemma differentiable_within_at.smul_const
(hc : differentiable_within_at 𝕜 c s x) (f : F) :
differentiable_within_at 𝕜 (λ y, c y • f) s x :=
(hc.has_fderiv_within_at.smul_const f).differentiable_within_at
lemma differentiable_at.smul_const (hc : differentiable_at 𝕜 c x) (f : F) :
differentiable_at 𝕜 (λ y, c y • f) x :=
(hc.has_fderiv_at.smul_const f).differentiable_at
lemma differentiable_on.smul_const (hc : differentiable_on 𝕜 c s) (f : F) :
differentiable_on 𝕜 (λ y, c y • f) s :=
λx hx, (hc x hx).smul_const f
lemma differentiable.smul_const (hc : differentiable 𝕜 c) (f : F) :
differentiable 𝕜 (λ y, c y • f) :=
λx, (hc x).smul_const f
lemma fderiv_within_smul_const (hxs : unique_diff_within_at 𝕜 s x)
(hc : differentiable_within_at 𝕜 c s x) (f : F) :
fderiv_within 𝕜 (λ y, c y • f) s x =
(fderiv_within 𝕜 c s x).smul_right f :=
(hc.has_fderiv_within_at.smul_const f).fderiv_within hxs
lemma fderiv_smul_const (hc : differentiable_at 𝕜 c x) (f : F) :
fderiv 𝕜 (λ y, c y • f) x = (fderiv 𝕜 c x).smul_right f :=
(hc.has_fderiv_at.smul_const f).fderiv
end smul
section mul
/-! ### Derivative of the product of two scalar-valued functions -/
variables {c d : E → 𝕜} {c' d' : E →L[𝕜] 𝕜}
theorem has_strict_fderiv_at.mul
(hc : has_strict_fderiv_at c c' x) (hd : has_strict_fderiv_at d d' x) :
has_strict_fderiv_at (λ y, c y * d y) (c x • d' + d x • c') x :=
by { convert hc.smul hd, ext z, apply mul_comm }
theorem has_fderiv_within_at.mul
(hc : has_fderiv_within_at c c' s x) (hd : has_fderiv_within_at d d' s x) :
has_fderiv_within_at (λ y, c y * d y) (c x • d' + d x • c') s x :=
by { convert hc.smul hd, ext z, apply mul_comm }
theorem has_fderiv_at.mul (hc : has_fderiv_at c c' x) (hd : has_fderiv_at d d' x) :
has_fderiv_at (λ y, c y * d y) (c x • d' + d x • c') x :=
by { convert hc.smul hd, ext z, apply mul_comm }
lemma differentiable_within_at.mul
(hc : differentiable_within_at 𝕜 c s x) (hd : differentiable_within_at 𝕜 d s x) :
differentiable_within_at 𝕜 (λ y, c y * d y) s x :=
(hc.has_fderiv_within_at.mul hd.has_fderiv_within_at).differentiable_within_at
@[simp] lemma differentiable_at.mul (hc : differentiable_at 𝕜 c x) (hd : differentiable_at 𝕜 d x) :
differentiable_at 𝕜 (λ y, c y * d y) x :=
(hc.has_fderiv_at.mul hd.has_fderiv_at).differentiable_at
lemma differentiable_on.mul (hc : differentiable_on 𝕜 c s) (hd : differentiable_on 𝕜 d s) :
differentiable_on 𝕜 (λ y, c y * d y) s :=
λx hx, (hc x hx).mul (hd x hx)
@[simp] lemma differentiable.mul (hc : differentiable 𝕜 c) (hd : differentiable 𝕜 d) :
differentiable 𝕜 (λ y, c y * d y) :=
λx, (hc x).mul (hd x)
lemma fderiv_within_mul (hxs : unique_diff_within_at 𝕜 s x)
(hc : differentiable_within_at 𝕜 c s x) (hd : differentiable_within_at 𝕜 d s x) :
fderiv_within 𝕜 (λ y, c y * d y) s x =
c x • fderiv_within 𝕜 d s x + d x • fderiv_within 𝕜 c s x :=
(hc.has_fderiv_within_at.mul hd.has_fderiv_within_at).fderiv_within hxs
lemma fderiv_mul (hc : differentiable_at 𝕜 c x) (hd : differentiable_at 𝕜 d x) :
fderiv 𝕜 (λ y, c y * d y) x =
c x • fderiv 𝕜 d x + d x • fderiv 𝕜 c x :=
(hc.has_fderiv_at.mul hd.has_fderiv_at).fderiv
theorem has_strict_fderiv_at.mul_const (hc : has_strict_fderiv_at c c' x) (d : 𝕜) :
has_strict_fderiv_at (λ y, c y * d) (d • c') x :=
by simpa only [smul_zero, zero_add] using hc.mul (has_strict_fderiv_at_const d x)
theorem has_fderiv_within_at.mul_const (hc : has_fderiv_within_at c c' s x) (d : 𝕜) :
has_fderiv_within_at (λ y, c y * d) (d • c') s x :=
by simpa only [smul_zero, zero_add] using hc.mul (has_fderiv_within_at_const d x s)
theorem has_fderiv_at.mul_const (hc : has_fderiv_at c c' x) (d : 𝕜) :
has_fderiv_at (λ y, c y * d) (d • c') x :=
begin
rw [← has_fderiv_within_at_univ] at *,
exact hc.mul_const d
end
lemma differentiable_within_at.mul_const
(hc : differentiable_within_at 𝕜 c s x) (d : 𝕜) :
differentiable_within_at 𝕜 (λ y, c y * d) s x :=
(hc.has_fderiv_within_at.mul_const d).differentiable_within_at
lemma differentiable_at.mul_const (hc : differentiable_at 𝕜 c x) (d : 𝕜) :
differentiable_at 𝕜 (λ y, c y * d) x :=
(hc.has_fderiv_at.mul_const d).differentiable_at
lemma differentiable_on.mul_const (hc : differentiable_on 𝕜 c s) (d : 𝕜) :
differentiable_on 𝕜 (λ y, c y * d) s :=
λx hx, (hc x hx).mul_const d
lemma differentiable.mul_const (hc : differentiable 𝕜 c) (d : 𝕜) :
differentiable 𝕜 (λ y, c y * d) :=
λx, (hc x).mul_const d
lemma fderiv_within_mul_const (hxs : unique_diff_within_at 𝕜 s x)
(hc : differentiable_within_at 𝕜 c s x) (d : 𝕜) :
fderiv_within 𝕜 (λ y, c y * d) s x = d • fderiv_within 𝕜 c s x :=
(hc.has_fderiv_within_at.mul_const d).fderiv_within hxs
lemma fderiv_mul_const (hc : differentiable_at 𝕜 c x) (d : 𝕜) :
fderiv 𝕜 (λ y, c y * d) x = d • fderiv 𝕜 c x :=
(hc.has_fderiv_at.mul_const d).fderiv
theorem has_strict_fderiv_at.const_mul (hc : has_strict_fderiv_at c c' x) (d : 𝕜) :
has_strict_fderiv_at (λ y, d * c y) (d • c') x :=
begin
simp only [mul_comm d],
exact hc.mul_const d,
end
theorem has_fderiv_within_at.const_mul
(hc : has_fderiv_within_at c c' s x) (d : 𝕜) :
has_fderiv_within_at (λ y, d * c y) (d • c') s x :=
begin
simp only [mul_comm d],
exact hc.mul_const d,
end
theorem has_fderiv_at.const_mul (hc : has_fderiv_at c c' x) (d : 𝕜) :
has_fderiv_at (λ y, d * c y) (d • c') x :=
begin
simp only [mul_comm d],
exact hc.mul_const d,
end
lemma differentiable_within_at.const_mul
(hc : differentiable_within_at 𝕜 c s x) (d : 𝕜) :
differentiable_within_at 𝕜 (λ y, d * c y) s x :=
(hc.has_fderiv_within_at.const_mul d).differentiable_within_at
lemma differentiable_at.const_mul (hc : differentiable_at 𝕜 c x) (d : 𝕜) :
differentiable_at 𝕜 (λ y, d * c y) x :=
(hc.has_fderiv_at.const_mul d).differentiable_at
lemma differentiable_on.const_mul (hc : differentiable_on 𝕜 c s) (d : 𝕜) :
differentiable_on 𝕜 (λ y, d * c y) s :=
λx hx, (hc x hx).const_mul d
lemma differentiable.const_mul (hc : differentiable 𝕜 c) (d : 𝕜) :
differentiable 𝕜 (λ y, d * c y) :=
λx, (hc x).const_mul d
lemma fderiv_within_const_mul (hxs : unique_diff_within_at 𝕜 s x)
(hc : differentiable_within_at 𝕜 c s x) (d : 𝕜) :
fderiv_within 𝕜 (λ y, d * c y) s x = d • fderiv_within 𝕜 c s x :=
(hc.has_fderiv_within_at.const_mul d).fderiv_within hxs
lemma fderiv_const_mul (hc : differentiable_at 𝕜 c x) (d : 𝕜) :
fderiv 𝕜 (λ y, d * c y) x = d • fderiv 𝕜 c x :=
(hc.has_fderiv_at.const_mul d).fderiv
end mul
section algebra_inverse
variables {R :Type*} [normed_ring R] [normed_algebra 𝕜 R] [complete_space R]
open normed_ring continuous_linear_map ring
/-- At an invertible element `x` of a normed algebra `R`, the Fréchet derivative of the inversion
operation is the linear map `λ t, - x⁻¹ * t * x⁻¹`. -/
lemma has_fderiv_at_ring_inverse (x : units R) :
has_fderiv_at ring.inverse (- (lmul_right 𝕜 R ↑x⁻¹).comp (lmul_left 𝕜 R ↑x⁻¹)) x :=
begin
have h_is_o : is_o (λ (t : R), inverse (↑x + t) - ↑x⁻¹ + ↑x⁻¹ * t * ↑x⁻¹)
(λ (t : R), t) (𝓝 0),
{ refine (inverse_add_norm_diff_second_order x).trans_is_o ((is_o_norm_norm).mp _),
simp only [normed_field.norm_pow, norm_norm],
have h12 : 1 < 2 := by norm_num,
convert (asymptotics.is_o_pow_pow h12).comp_tendsto lim_norm_zero,
ext, simp },
have h_lim : tendsto (λ (y:R), y - x) (𝓝 x) (𝓝 0),
{ refine tendsto_zero_iff_norm_tendsto_zero.mpr _,
exact tendsto_iff_norm_tendsto_zero.mp tendsto_id },
simp only [has_fderiv_at, has_fderiv_at_filter],
convert h_is_o.comp_tendsto h_lim,
ext y,
simp only [coe_comp', function.comp_app, lmul_right_apply, lmul_left_apply, neg_apply,
inverse_unit x, units.inv_mul, add_sub_cancel'_right, mul_sub, sub_mul, one_mul],
abel
end
lemma differentiable_at_inverse (x : units R) : differentiable_at 𝕜 (@ring.inverse R _) x :=
(has_fderiv_at_ring_inverse x).differentiable_at
lemma fderiv_inverse (x : units R) :
fderiv 𝕜 (@ring.inverse R _) x = - (lmul_right 𝕜 R ↑x⁻¹).comp (lmul_left 𝕜 R ↑x⁻¹) :=
(has_fderiv_at_ring_inverse x).fderiv
end algebra_inverse
section continuous_linear_equiv
/-! ### Differentiability of linear equivs, and invariance of differentiability -/
variable (iso : E ≃L[𝕜] F)
protected lemma continuous_linear_equiv.has_strict_fderiv_at :
has_strict_fderiv_at iso (iso : E →L[𝕜] F) x :=
iso.to_continuous_linear_map.has_strict_fderiv_at
protected lemma continuous_linear_equiv.has_fderiv_within_at :
has_fderiv_within_at iso (iso : E →L[𝕜] F) s x :=
iso.to_continuous_linear_map.has_fderiv_within_at
protected lemma continuous_linear_equiv.has_fderiv_at : has_fderiv_at iso (iso : E →L[𝕜] F) x :=
iso.to_continuous_linear_map.has_fderiv_at_filter
protected lemma continuous_linear_equiv.differentiable_at : differentiable_at 𝕜 iso x :=
iso.has_fderiv_at.differentiable_at
protected lemma continuous_linear_equiv.differentiable_within_at :
differentiable_within_at 𝕜 iso s x :=
iso.differentiable_at.differentiable_within_at
protected lemma continuous_linear_equiv.fderiv : fderiv 𝕜 iso x = iso :=
iso.has_fderiv_at.fderiv
protected lemma continuous_linear_equiv.fderiv_within (hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 iso s x = iso :=
iso.to_continuous_linear_map.fderiv_within hxs
protected lemma continuous_linear_equiv.differentiable : differentiable 𝕜 iso :=
λx, iso.differentiable_at
protected lemma continuous_linear_equiv.differentiable_on : differentiable_on 𝕜 iso s :=
iso.differentiable.differentiable_on
lemma continuous_linear_equiv.comp_differentiable_within_at_iff {f : G → E} {s : set G} {x : G} :
differentiable_within_at 𝕜 (iso ∘ f) s x ↔ differentiable_within_at 𝕜 f s x :=
begin
refine ⟨λ H, _, λ H, iso.differentiable.differentiable_at.comp_differentiable_within_at x H⟩,
have : differentiable_within_at 𝕜 (iso.symm ∘ (iso ∘ f)) s x :=
iso.symm.differentiable.differentiable_at.comp_differentiable_within_at x H,
rwa [← function.comp.assoc iso.symm iso f, iso.symm_comp_self] at this,
end
lemma continuous_linear_equiv.comp_differentiable_at_iff {f : G → E} {x : G} :
differentiable_at 𝕜 (iso ∘ f) x ↔ differentiable_at 𝕜 f x :=
by rw [← differentiable_within_at_univ, ← differentiable_within_at_univ,
iso.comp_differentiable_within_at_iff]
lemma continuous_linear_equiv.comp_differentiable_on_iff {f : G → E} {s : set G} :
differentiable_on 𝕜 (iso ∘ f) s ↔ differentiable_on 𝕜 f s :=
begin
rw [differentiable_on, differentiable_on],
simp only [iso.comp_differentiable_within_at_iff],
end
lemma continuous_linear_equiv.comp_differentiable_iff {f : G → E} :
differentiable 𝕜 (iso ∘ f) ↔ differentiable 𝕜 f :=
begin
rw [← differentiable_on_univ, ← differentiable_on_univ],
exact iso.comp_differentiable_on_iff
end
lemma continuous_linear_equiv.comp_has_fderiv_within_at_iff
{f : G → E} {s : set G} {x : G} {f' : G →L[𝕜] E} :
has_fderiv_within_at (iso ∘ f) ((iso : E →L[𝕜] F).comp f') s x ↔ has_fderiv_within_at f f' s x :=
begin
refine ⟨λ H, _, λ H, iso.has_fderiv_at.comp_has_fderiv_within_at x H⟩,
have A : f = iso.symm ∘ (iso ∘ f), by { rw [← function.comp.assoc, iso.symm_comp_self], refl },
have B : f' = (iso.symm : F →L[𝕜] E).comp ((iso : E →L[𝕜] F).comp f'),
by rw [← continuous_linear_map.comp_assoc, iso.coe_symm_comp_coe, continuous_linear_map.id_comp],
rw [A, B],
exact iso.symm.has_fderiv_at.comp_has_fderiv_within_at x H
end
lemma continuous_linear_equiv.comp_has_strict_fderiv_at_iff {f : G → E} {x : G} {f' : G →L[𝕜] E} :
has_strict_fderiv_at (iso ∘ f) ((iso : E →L[𝕜] F).comp f') x ↔ has_strict_fderiv_at f f' x :=
begin
refine ⟨λ H, _, λ H, iso.has_strict_fderiv_at.comp x H⟩,
convert iso.symm.has_strict_fderiv_at.comp x H; ext z; apply (iso.symm_apply_apply _).symm
end
lemma continuous_linear_equiv.comp_has_fderiv_at_iff {f : G → E} {x : G} {f' : G →L[𝕜] E} :
has_fderiv_at (iso ∘ f) ((iso : E →L[𝕜] F).comp f') x ↔ has_fderiv_at f f' x :=
by rw [← has_fderiv_within_at_univ, ← has_fderiv_within_at_univ, iso.comp_has_fderiv_within_at_iff]
lemma continuous_linear_equiv.comp_has_fderiv_within_at_iff'
{f : G → E} {s : set G} {x : G} {f' : G →L[𝕜] F} :
has_fderiv_within_at (iso ∘ f) f' s x ↔
has_fderiv_within_at f ((iso.symm : F →L[𝕜] E).comp f') s x :=
by rw [← iso.comp_has_fderiv_within_at_iff, ← continuous_linear_map.comp_assoc,
iso.coe_comp_coe_symm, continuous_linear_map.id_comp]
lemma continuous_linear_equiv.comp_has_fderiv_at_iff' {f : G → E} {x : G} {f' : G →L[𝕜] F} :
has_fderiv_at (iso ∘ f) f' x ↔ has_fderiv_at f ((iso.symm : F →L[𝕜] E).comp f') x :=
by rw [← has_fderiv_within_at_univ, ← has_fderiv_within_at_univ, iso.comp_has_fderiv_within_at_iff']
lemma continuous_linear_equiv.comp_fderiv_within {f : G → E} {s : set G} {x : G}
(hxs : unique_diff_within_at 𝕜 s x) :
fderiv_within 𝕜 (iso ∘ f) s x = (iso : E →L[𝕜] F).comp (fderiv_within 𝕜 f s x) :=
begin
by_cases h : differentiable_within_at 𝕜 f s x,
{ rw [fderiv.comp_fderiv_within x iso.differentiable_at h hxs, iso.fderiv] },
{ have : ¬differentiable_within_at 𝕜 (iso ∘ f) s x,
from mt iso.comp_differentiable_within_at_iff.1 h,
rw [fderiv_within_zero_of_not_differentiable_within_at h,
fderiv_within_zero_of_not_differentiable_within_at this,
continuous_linear_map.comp_zero] }
end
lemma continuous_linear_equiv.comp_fderiv {f : G → E} {x : G} :
fderiv 𝕜 (iso ∘ f) x = (iso : E →L[𝕜] F).comp (fderiv 𝕜 f x) :=
begin
rw [← fderiv_within_univ, ← fderiv_within_univ],
exact iso.comp_fderiv_within unique_diff_within_at_univ,
end
end continuous_linear_equiv
/-- If `f (g y) = y` for `y` in some neighborhood of `a`, `g` is continuous at `a`, and `f` has an
invertible derivative `f'` at `g a` in the strict sense, then `g` has the derivative `f'⁻¹` at `a`
in the strict sense.
This is one of the easy parts of the inverse function theorem: it assumes that we already have an
inverse function. -/
theorem has_strict_fderiv_at.of_local_left_inverse {f : E → F} {f' : E ≃L[𝕜] F} {g : F → E} {a : F}
(hg : continuous_at g a) (hf : has_strict_fderiv_at f (f' : E →L[𝕜] F) (g a))
(hfg : ∀ᶠ y in 𝓝 a, f (g y) = y) :
has_strict_fderiv_at g (f'.symm : F →L[𝕜] E) a :=
begin
replace hg := hg.prod_map' hg,
replace hfg := hfg.prod_mk_nhds hfg,
have : is_O (λ p : F × F, g p.1 - g p.2 - f'.symm (p.1 - p.2))
(λ p : F × F, f' (g p.1 - g p.2) - (p.1 - p.2)) (𝓝 (a, a)),
{ refine ((f'.symm : F →L[𝕜] E).is_O_comp _ _).congr (λ x, _) (λ _, rfl),
simp },
refine this.trans_is_o _, clear this,
refine ((hf.comp_tendsto hg).symm.congr' (hfg.mono _)
(eventually_of_forall $ λ _, rfl)).trans_is_O _,
{ rintros p ⟨hp1, hp2⟩,
simp [hp1, hp2] },
{ refine (hf.is_O_sub_rev.comp_tendsto hg).congr'
(eventually_of_forall $ λ _, rfl) (hfg.mono _),
rintros p ⟨hp1, hp2⟩,
simp only [(∘), hp1, hp2] }
end
/-- If `f (g y) = y` for `y` in some neighborhood of `a`, `g` is continuous at `a`, and `f` has an
invertible derivative `f'` at `g a`, then `g` has the derivative `f'⁻¹` at `a`.
This is one of the easy parts of the inverse function theorem: it assumes that we already have
an inverse function. -/
theorem has_fderiv_at.of_local_left_inverse {f : E → F} {f' : E ≃L[𝕜] F} {g : F → E} {a : F}
(hg : continuous_at g a) (hf : has_fderiv_at f (f' : E →L[𝕜] F) (g a))
(hfg : ∀ᶠ y in 𝓝 a, f (g y) = y) :
has_fderiv_at g (f'.symm : F →L[𝕜] E) a :=
begin
have : is_O (λ x : F, g x - g a - f'.symm (x - a)) (λ x : F, f' (g x - g a) - (x - a)) (𝓝 a),
{ refine ((f'.symm : F →L[𝕜] E).is_O_comp _ _).congr (λ x, _) (λ _, rfl),
simp },
refine this.trans_is_o _, clear this,
refine ((hf.comp_tendsto hg).symm.congr' (hfg.mono _)
(eventually_of_forall $ λ _, rfl)).trans_is_O _,
{ rintros p hp,
simp [hp, hfg.self_of_nhds] },
{ refine (hf.is_O_sub_rev.comp_tendsto hg).congr'
(eventually_of_forall $ λ _, rfl) (hfg.mono _),
rintros p hp,
simp only [(∘), hp, hfg.self_of_nhds] }
end
/-- If `f` is a local homeomorphism defined on a neighbourhood of `f.symm a`, and `f` has an
invertible derivative `f'` at `f.symm a`, then `f.symm` has the derivative `f'⁻¹` at `a`.
This is one of the easy parts of the inverse function theorem: it assumes that we already have
an inverse function. -/
lemma has_fderiv_at.of_local_homeomorph {f : local_homeomorph E F} {f' : E ≃L[𝕜] F} {a : F}
(ha : a ∈ f.target) (htff' : has_fderiv_at f (f' : E →L[𝕜] F) (f.symm a)) :
has_fderiv_at f.symm (f'.symm : F →L[𝕜] E) a :=
htff'.of_local_left_inverse (f.symm.continuous_at ha) (f.eventually_right_inverse ha)
end
section
/-
In the special case of a normed space over the reals,
we can use scalar multiplication in the `tendsto` characterization
of the Fréchet derivative.
-/
variables {E : Type*} [normed_group E] [normed_space ℝ E]
variables {F : Type*} [normed_group F] [normed_space ℝ F]
variables {f : E → F} {f' : E →L[ℝ] F} {x : E}
theorem has_fderiv_at_filter_real_equiv {L : filter E} :
tendsto (λ x' : E, ∥x' - x∥⁻¹ * ∥f x' - f x - f' (x' - x)∥) L (𝓝 0) ↔
tendsto (λ x' : E, ∥x' - x∥⁻¹ • (f x' - f x - f' (x' - x))) L (𝓝 0) :=
begin
symmetry,
rw [tendsto_iff_norm_tendsto_zero], refine tendsto_congr (λ x', _),
have : ∥x' - x∥⁻¹ ≥ 0, from inv_nonneg.mpr (norm_nonneg _),
simp [norm_smul, real.norm_eq_abs, abs_of_nonneg this]
end
lemma has_fderiv_at.lim_real (hf : has_fderiv_at f f' x) (v : E) :
tendsto (λ (c:ℝ), c • (f (x + c⁻¹ • v) - f x)) at_top (𝓝 (f' v)) :=
begin
apply hf.lim v,
rw tendsto_at_top_at_top,
exact λ b, ⟨b, λ a ha, le_trans ha (le_abs_self _)⟩
end
end
section tangent_cone
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{F : Type*} [normed_group F] [normed_space 𝕜 F]
{f : E → F} {s : set E} {f' : E →L[𝕜] F}
/-- The image of a tangent cone under the differential of a map is included in the tangent cone to
the image. -/
lemma has_fderiv_within_at.maps_to_tangent_cone {x : E} (h : has_fderiv_within_at f f' s x) :
maps_to f' (tangent_cone_at 𝕜 s x) (tangent_cone_at 𝕜 (f '' s) (f x)) :=
begin
rintros v ⟨c, d, dtop, clim, cdlim⟩,
refine ⟨c, (λn, f (x + d n) - f x), mem_sets_of_superset dtop _, clim, h.lim at_top dtop clim cdlim⟩,
simp [-mem_image, mem_image_of_mem] {contextual := tt}
end
/-- If a set has the unique differentiability property at a point x, then the image of this set
under a map with onto derivative has also the unique differentiability property at the image point.
-/
lemma has_fderiv_within_at.unique_diff_within_at {x : E} (h : has_fderiv_within_at f f' s x)
(hs : unique_diff_within_at 𝕜 s x) (h' : closure (range f') = univ) :
unique_diff_within_at 𝕜 (f '' s) (f x) :=
begin
have B : ∀v ∈ (submodule.span 𝕜 (tangent_cone_at 𝕜 s x) : set E),
f' v ∈ (submodule.span 𝕜 (tangent_cone_at 𝕜 (f '' s) (f x)) : set F),
{ assume v hv,
apply submodule.span_induction hv,
{ exact λ w hw, submodule.subset_span (h.maps_to_tangent_cone hw) },
{ simp },
{ assume w₁ w₂ hw₁ hw₂,
rw continuous_linear_map.map_add,
exact submodule.add_mem (submodule.span 𝕜 (tangent_cone_at 𝕜 (f '' s) (f x))) hw₁ hw₂ },
{ assume a w hw,
rw continuous_linear_map.map_smul,
exact submodule.smul_mem (submodule.span 𝕜 (tangent_cone_at 𝕜 (f '' s) (f x))) _ hw } },
rw [unique_diff_within_at, ← univ_subset_iff],
split,
show f x ∈ closure (f '' s), from h.continuous_within_at.mem_closure_image hs.2,
show univ ⊆ closure ↑(submodule.span 𝕜 (tangent_cone_at 𝕜 (f '' s) (f x))), from calc
univ ⊆ closure (range f') : univ_subset_iff.2 h'
... = closure (f' '' univ) : by rw image_univ
... = closure (f' '' (closure (submodule.span 𝕜 (tangent_cone_at 𝕜 s x) : set E))) : by rw hs.1
... ⊆ closure (closure (f' '' (submodule.span 𝕜 (tangent_cone_at 𝕜 s x) : set E))) :
closure_mono (image_closure_subset_closure_image f'.cont)
... = closure (f' '' (submodule.span 𝕜 (tangent_cone_at 𝕜 s x) : set E)) : closure_closure
... ⊆ closure (submodule.span 𝕜 (tangent_cone_at 𝕜 (f '' s) (f x)) : set F) :
closure_mono (image_subset_iff.mpr B)
end
lemma has_fderiv_within_at.unique_diff_within_at_of_continuous_linear_equiv
{x : E} (e' : E ≃L[𝕜] F) (h : has_fderiv_within_at f (e' : E →L[𝕜] F) s x)
(hs : unique_diff_within_at 𝕜 s x) :
unique_diff_within_at 𝕜 (f '' s) (f x) :=
begin
apply h.unique_diff_within_at hs,
have : set.range (e' : E →L[𝕜] F) = univ := e'.to_linear_equiv.to_equiv.range_eq_univ,
rw [this, closure_univ]
end
lemma continuous_linear_equiv.unique_diff_on_preimage_iff (e : F ≃L[𝕜] E) :
unique_diff_on 𝕜 (e ⁻¹' s) ↔ unique_diff_on 𝕜 s :=
begin
split,
{ assume hs x hx,
have A : s = e '' (e.symm '' s) :=
(equiv.symm_image_image (e.symm.to_linear_equiv.to_equiv) s).symm,
have B : e.symm '' s = e⁻¹' s :=
equiv.image_eq_preimage e.symm.to_linear_equiv.to_equiv s,
rw [A, B, (e.apply_symm_apply x).symm],
refine has_fderiv_within_at.unique_diff_within_at_of_continuous_linear_equiv e
e.has_fderiv_within_at (hs _ _),
rwa [mem_preimage, e.apply_symm_apply x] },
{ assume hs x hx,
have : e ⁻¹' s = e.symm '' s :=
(equiv.image_eq_preimage e.symm.to_linear_equiv.to_equiv s).symm,
rw [this, (e.symm_apply_apply x).symm],
exact has_fderiv_within_at.unique_diff_within_at_of_continuous_linear_equiv e.symm
e.symm.has_fderiv_within_at (hs _ hx) },
end
end tangent_cone
section restrict_scalars
/-!
### Restricting from `ℂ` to `ℝ`, or generally from `𝕜'` to `𝕜`
If a function is differentiable over `ℂ`, then it is differentiable over `ℝ`. In this paragraph,
we give variants of this statement, in the general situation where `ℂ` and `ℝ` are replaced
respectively by `𝕜'` and `𝕜` where `𝕜'` is a normed algebra over `𝕜`.
-/
variables (𝕜 : Type*) [nondiscrete_normed_field 𝕜]
{𝕜' : Type*} [nondiscrete_normed_field 𝕜'] [normed_algebra 𝕜 𝕜']
{E : Type*} [normed_group E] [normed_space 𝕜' E]
{F : Type*} [normed_group F] [normed_space 𝕜' F]
{f : semimodule.restrict_scalars 𝕜 𝕜' E → semimodule.restrict_scalars 𝕜 𝕜' F}
{f' : semimodule.restrict_scalars 𝕜 𝕜' E →L[𝕜'] semimodule.restrict_scalars 𝕜 𝕜' F} {s : set E} {x : E}
lemma has_strict_fderiv_at.restrict_scalars (h : has_strict_fderiv_at f f' x) :
has_strict_fderiv_at f (f'.restrict_scalars 𝕜) x := h
lemma has_fderiv_at.restrict_scalars (h : has_fderiv_at f f' x) :
has_fderiv_at f (f'.restrict_scalars 𝕜) x := h
lemma has_fderiv_within_at.restrict_scalars (h : has_fderiv_within_at f f' s x) :
has_fderiv_within_at f (f'.restrict_scalars 𝕜) s x := h
lemma differentiable_at.restrict_scalars (h : differentiable_at 𝕜' f x) :
differentiable_at 𝕜 f x :=
(h.has_fderiv_at.restrict_scalars 𝕜).differentiable_at
lemma differentiable_within_at.restrict_scalars (h : differentiable_within_at 𝕜' f s x) :
differentiable_within_at 𝕜 f s x :=
(h.has_fderiv_within_at.restrict_scalars 𝕜).differentiable_within_at
lemma differentiable_on.restrict_scalars (h : differentiable_on 𝕜' f s) :
differentiable_on 𝕜 f s :=
λx hx, (h x hx).restrict_scalars 𝕜
lemma differentiable.restrict_scalars (h : differentiable 𝕜' f) :
differentiable 𝕜 f :=
λx, (h x).restrict_scalars 𝕜
end restrict_scalars
/-!
### Multiplying by a complex function respects real differentiability
Consider two functions `c : E → ℂ` and `f : E → F` where `F` is a complex vector space. If both
`c` and `f` are differentiable over `ℝ`, then so is their product. This paragraph proves this
statement, in the general version where `ℝ` is replaced by a field `𝕜`, and `ℂ` is replaced
by a normed algebra `𝕜'` over `𝕜`.
-/
section smul_algebra
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
{𝕜' : Type*} [nondiscrete_normed_field 𝕜'] [normed_algebra 𝕜 𝕜']
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{F : Type*} [normed_group F] [normed_space 𝕜' F]
{f : E → semimodule.restrict_scalars 𝕜 𝕜' F}
{f' : E →L[𝕜] semimodule.restrict_scalars 𝕜 𝕜' F} {s : set E} {x : E}
{c : E → 𝕜'} {c' : E →L[𝕜] 𝕜'} {L : filter E}
theorem has_strict_fderiv_at.smul_algebra (hc : has_strict_fderiv_at c c' x)
(hf : has_strict_fderiv_at f f' x) :
has_strict_fderiv_at (λ y, c y • f y) (c x • f' + c'.smul_algebra_right (f x)) x :=
(is_bounded_bilinear_map_smul_algebra.has_strict_fderiv_at (c x, f x)).comp x $
hc.prod hf
theorem has_fderiv_within_at.smul_algebra
(hc : has_fderiv_within_at c c' s x) (hf : has_fderiv_within_at f f' s x) :
has_fderiv_within_at (λ y, c y • f y) (c x • f' + c'.smul_algebra_right (f x)) s x :=
(is_bounded_bilinear_map_smul_algebra.has_fderiv_at (c x, f x)).comp_has_fderiv_within_at x $
hc.prod hf
theorem has_fderiv_at.smul_algebra (hc : has_fderiv_at c c' x) (hf : has_fderiv_at f f' x) :
has_fderiv_at (λ y, c y • f y) (c x • f' + c'.smul_algebra_right (f x)) x :=
(is_bounded_bilinear_map_smul_algebra.has_fderiv_at (c x, f x)).comp x $
hc.prod hf
lemma differentiable_within_at.smul_algebra
(hc : differentiable_within_at 𝕜 c s x) (hf : differentiable_within_at 𝕜 f s x) :
differentiable_within_at 𝕜 (λ y, c y • f y) s x :=
(hc.has_fderiv_within_at.smul_algebra hf.has_fderiv_within_at).differentiable_within_at
@[simp] lemma differentiable_at.smul_algebra
(hc : differentiable_at 𝕜 c x) (hf : differentiable_at 𝕜 f x) :
differentiable_at 𝕜 (λ y, c y • f y) x :=
(hc.has_fderiv_at.smul_algebra hf.has_fderiv_at).differentiable_at
lemma differentiable_on.smul_algebra (hc : differentiable_on 𝕜 c s) (hf : differentiable_on 𝕜 f s) :
differentiable_on 𝕜 (λ y, c y • f y) s :=
λx hx, (hc x hx).smul_algebra (hf x hx)
@[simp] lemma differentiable.smul_algebra (hc : differentiable 𝕜 c) (hf : differentiable 𝕜 f) :
differentiable 𝕜 (λ y, c y • f y) :=
λx, (hc x).smul_algebra (hf x)
lemma fderiv_within_smul_algebra (hxs : unique_diff_within_at 𝕜 s x)
(hc : differentiable_within_at 𝕜 c s x) (hf : differentiable_within_at 𝕜 f s x) :
fderiv_within 𝕜 (λ y, c y • f y) s x =
c x • fderiv_within 𝕜 f s x + (fderiv_within 𝕜 c s x).smul_algebra_right (f x) :=
(hc.has_fderiv_within_at.smul_algebra hf.has_fderiv_within_at).fderiv_within hxs
lemma fderiv_smul_algebra (hc : differentiable_at 𝕜 c x) (hf : differentiable_at 𝕜 f x) :
fderiv 𝕜 (λ y, c y • f y) x =
c x • fderiv 𝕜 f x + (fderiv 𝕜 c x).smul_algebra_right (f x) :=
(hc.has_fderiv_at.smul_algebra hf.has_fderiv_at).fderiv
theorem has_strict_fderiv_at.smul_algebra_const
(hc : has_strict_fderiv_at c c' x) (f : semimodule.restrict_scalars 𝕜 𝕜' F) :
has_strict_fderiv_at (λ y, c y • f) (c'.smul_algebra_right f) x :=
by simpa only [smul_zero, zero_add] using hc.smul_algebra (has_strict_fderiv_at_const f x)
theorem has_fderiv_within_at.smul_algebra_const
(hc : has_fderiv_within_at c c' s x) (f : semimodule.restrict_scalars 𝕜 𝕜' F) :
has_fderiv_within_at (λ y, c y • f) (c'.smul_algebra_right f) s x :=
by simpa only [smul_zero, zero_add] using hc.smul_algebra (has_fderiv_within_at_const f x s)
theorem has_fderiv_at.smul_algebra_const
(hc : has_fderiv_at c c' x) (f : semimodule.restrict_scalars 𝕜 𝕜' F) :
has_fderiv_at (λ y, c y • f) (c'.smul_algebra_right f) x :=
by simpa only [smul_zero, zero_add] using hc.smul_algebra (has_fderiv_at_const f x)
lemma differentiable_within_at.smul_algebra_const
(hc : differentiable_within_at 𝕜 c s x) (f : semimodule.restrict_scalars 𝕜 𝕜' F) :
differentiable_within_at 𝕜 (λ y, c y • f) s x :=
(hc.has_fderiv_within_at.smul_algebra_const f).differentiable_within_at
lemma differentiable_at.smul_algebra_const
(hc : differentiable_at 𝕜 c x) (f : semimodule.restrict_scalars 𝕜 𝕜' F) :
differentiable_at 𝕜 (λ y, c y • f) x :=
(hc.has_fderiv_at.smul_algebra_const f).differentiable_at
lemma differentiable_on.smul_algebra_const
(hc : differentiable_on 𝕜 c s) (f : semimodule.restrict_scalars 𝕜 𝕜' F) :
differentiable_on 𝕜 (λ y, c y • f) s :=
λx hx, (hc x hx).smul_algebra_const f
lemma differentiable.smul_algebra_const
(hc : differentiable 𝕜 c) (f : semimodule.restrict_scalars 𝕜 𝕜' F) :
differentiable 𝕜 (λ y, c y • f) :=
λx, (hc x).smul_algebra_const f
lemma fderiv_within_smul_algebra_const (hxs : unique_diff_within_at 𝕜 s x)
(hc : differentiable_within_at 𝕜 c s x) (f : semimodule.restrict_scalars 𝕜 𝕜' F) :
fderiv_within 𝕜 (λ y, c y • f) s x =
(fderiv_within 𝕜 c s x).smul_algebra_right f :=
(hc.has_fderiv_within_at.smul_algebra_const f).fderiv_within hxs
lemma fderiv_smul_algebra_const
(hc : differentiable_at 𝕜 c x) (f : semimodule.restrict_scalars 𝕜 𝕜' F) :
fderiv 𝕜 (λ y, c y • f) x = (fderiv 𝕜 c x).smul_algebra_right f :=
(hc.has_fderiv_at.smul_algebra_const f).fderiv
theorem has_strict_fderiv_at.const_smul_algebra (h : has_strict_fderiv_at f f' x) (c : 𝕜') :
has_strict_fderiv_at (λ x, c • f x) (c • f') x :=
(c • (1 : (semimodule.restrict_scalars 𝕜 𝕜' F) →L[𝕜] ((semimodule.restrict_scalars 𝕜 𝕜' F))))
.has_strict_fderiv_at.comp x h
theorem has_fderiv_at_filter.const_smul_algebra (h : has_fderiv_at_filter f f' x L) (c : 𝕜') :
has_fderiv_at_filter (λ x, c • f x) (c • f') x L :=
(c • (1 : (semimodule.restrict_scalars 𝕜 𝕜' F) →L[𝕜] ((semimodule.restrict_scalars 𝕜 𝕜' F))))
.has_fderiv_at_filter.comp x h
theorem has_fderiv_within_at.const_smul_algebra (h : has_fderiv_within_at f f' s x) (c : 𝕜') :
has_fderiv_within_at (λ x, c • f x) (c • f') s x :=
h.const_smul_algebra c
theorem has_fderiv_at.const_smul_algebra (h : has_fderiv_at f f' x) (c : 𝕜') :
has_fderiv_at (λ x, c • f x) (c • f') x :=
h.const_smul_algebra c
lemma differentiable_within_at.const_smul_algebra (h : differentiable_within_at 𝕜 f s x) (c : 𝕜') :
differentiable_within_at 𝕜 (λy, c • f y) s x :=
(h.has_fderiv_within_at.const_smul_algebra c).differentiable_within_at
lemma differentiable_at.const_smul_algebra (h : differentiable_at 𝕜 f x) (c : 𝕜') :
differentiable_at 𝕜 (λy, c • f y) x :=
(h.has_fderiv_at.const_smul_algebra c).differentiable_at
lemma differentiable_on.const_smul_algebra (h : differentiable_on 𝕜 f s) (c : 𝕜') :
differentiable_on 𝕜 (λy, c • f y) s :=
λx hx, (h x hx).const_smul_algebra c
lemma differentiable.const_smul_algebra (h : differentiable 𝕜 f) (c : 𝕜') :
differentiable 𝕜 (λy, c • f y) :=
λx, (h x).const_smul_algebra c
lemma fderiv_within_const_smul_algebra (hxs : unique_diff_within_at 𝕜 s x)
(h : differentiable_within_at 𝕜 f s x) (c : 𝕜') :
fderiv_within 𝕜 (λy, c • f y) s x = c • fderiv_within 𝕜 f s x :=
(h.has_fderiv_within_at.const_smul_algebra c).fderiv_within hxs
lemma fderiv_const_smul_algebra (h : differentiable_at 𝕜 f x) (c : 𝕜') :
fderiv 𝕜 (λy, c • f y) x = c • fderiv 𝕜 f x :=
(h.has_fderiv_at.const_smul_algebra c).fderiv
end smul_algebra
|
2cdea05aedfe6c637b1cf3e8ff586b945be321ac | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/algebra/group_action_hom.lean | 4933ec1196fe3ab7cc4d317fe1563c9f2ea730e0 | [
"Apache-2.0"
] | permissive | jjgarzella/mathlib | 96a345378c4e0bf26cf604aed84f90329e4896a2 | 395d8716c3ad03747059d482090e2bb97db612c8 | refs/heads/master | 1,686,480,124,379 | 1,625,163,323,000 | 1,625,163,323,000 | 281,190,421 | 2 | 0 | Apache-2.0 | 1,595,268,170,000 | 1,595,268,169,000 | null | UTF-8 | Lean | false | false | 11,557 | lean | /-
Copyright (c) 2020 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau
-/
import algebra.group_ring_action
import group_theory.group_action
/-!
# Equivariant homomorphisms
## Main definitions
* `mul_action_hom M X Y`, the type of equivariant functions from `X` to `Y`, where `M` is a monoid
that acts on the types `X` and `Y`.
* `distrib_mul_action_hom M A B`, the type of equivariant additive monoid homomorphisms
from `A` to `B`, where `M` is a monoid that acts on the additive monoids `A` and `B`.
* `mul_semiring_action_hom M R S`, the type of equivariant ring homomorphisms
from `R` to `S`, where `M` is a monoid that acts on the rings `R` and `S`.
## Notations
* `X →[M] Y` is `mul_action_hom M X Y`.
* `A →+[M] B` is `distrib_mul_action_hom M X Y`.
* `R →+*[M] S` is `mul_semiring_action_hom M X Y`.
-/
variables (M' : Type*)
variables (X : Type*) [has_scalar M' X]
variables (Y : Type*) [has_scalar M' Y]
variables (Z : Type*) [has_scalar M' Z]
variables (M : Type*) [monoid M]
variables (A : Type*) [add_monoid A] [distrib_mul_action M A]
variables (A' : Type*) [add_group A'] [distrib_mul_action M A']
variables (B : Type*) [add_monoid B] [distrib_mul_action M B]
variables (B' : Type*) [add_group B'] [distrib_mul_action M B']
variables (C : Type*) [add_monoid C] [distrib_mul_action M C]
variables (R : Type*) [semiring R] [mul_semiring_action M R]
variables (R' : Type*) [ring R'] [mul_semiring_action M R']
variables (S : Type*) [semiring S] [mul_semiring_action M S]
variables (S' : Type*) [ring S'] [mul_semiring_action M S']
variables (T : Type*) [semiring T] [mul_semiring_action M T]
variables (G : Type*) [group G] (H : subgroup G)
set_option old_structure_cmd true
/-- Equivariant functions. -/
@[nolint has_inhabited_instance]
structure mul_action_hom :=
(to_fun : X → Y)
(map_smul' : ∀ (m : M') (x : X), to_fun (m • x) = m • to_fun x)
notation X ` →[`:25 M:25 `] `:0 Y:0 := mul_action_hom M X Y
namespace mul_action_hom
instance : has_coe_to_fun (X →[M'] Y) :=
⟨_, λ c, c.to_fun⟩
variables {M M' X Y}
@[simp] lemma map_smul (f : X →[M'] Y) (m : M') (x : X) : f (m • x) = m • f x :=
f.map_smul' m x
@[ext] theorem ext : ∀ {f g : X →[M'] Y}, (∀ x, f x = g x) → f = g
| ⟨f, _⟩ ⟨g, _⟩ H := by { congr' 1 with x, exact H x }
theorem ext_iff {f g : X →[M'] Y} : f = g ↔ ∀ x, f x = g x :=
⟨λ H x, by rw H, ext⟩
protected lemma congr_fun {f g : X →[M'] Y} (h : f = g) (x : X) : f x = g x := h ▸ rfl
variables (M M') {X}
/-- The identity map as an equivariant map. -/
protected def id : X →[M'] X :=
⟨id, λ _ _, rfl⟩
@[simp] lemma id_apply (x : X) : mul_action_hom.id M' x = x := rfl
variables {M M' X Y Z}
/-- Composition of two equivariant maps. -/
def comp (g : Y →[M'] Z) (f : X →[M'] Y) : X →[M'] Z :=
⟨g ∘ f, λ m x, calc
g (f (m • x)) = g (m • f x) : by rw f.map_smul
... = m • g (f x) : g.map_smul _ _⟩
@[simp] lemma comp_apply (g : Y →[M'] Z) (f : X →[M'] Y) (x : X) : g.comp f x = g (f x) := rfl
@[simp] lemma id_comp (f : X →[M'] Y) : (mul_action_hom.id M').comp f = f :=
ext $ λ x, by rw [comp_apply, id_apply]
@[simp] lemma comp_id (f : X →[M'] Y) : f.comp (mul_action_hom.id M') = f :=
ext $ λ x, by rw [comp_apply, id_apply]
variables {A B}
/-- The inverse of a bijective equivariant map is equivariant. -/
@[simps] def inverse (f : A →[M] B) (g : B → A)
(h₁ : function.left_inverse g f) (h₂ : function.right_inverse g f) :
B →[M] A :=
{ to_fun := g,
map_smul' := λ m x,
calc g (m • x) = g (m • (f (g x))) : by rw h₂
... = g (f (m • (g x))) : by rw f.map_smul
... = m • g x : by rw h₁, }
variables {G} (H)
/-- The canonical map to the left cosets. -/
def to_quotient : G →[G] quotient_group.quotient H :=
⟨coe, λ g x, rfl⟩
@[simp] lemma to_quotient_apply (g : G) : to_quotient H g = g := rfl
end mul_action_hom
/-- Equivariant additive monoid homomorphisms. -/
structure distrib_mul_action_hom extends A →[M] B, A →+ B.
/-- Reinterpret an equivariant additive monoid homomorphism as an additive monoid homomorphism. -/
add_decl_doc distrib_mul_action_hom.to_add_monoid_hom
/-- Reinterpret an equivariant additive monoid homomorphism as an equivariant function. -/
add_decl_doc distrib_mul_action_hom.to_mul_action_hom
notation A ` →+[`:25 M:25 `] `:0 B:0 := distrib_mul_action_hom M A B
namespace distrib_mul_action_hom
instance has_coe : has_coe (A →+[M] B) (A →+ B) :=
⟨to_add_monoid_hom⟩
instance has_coe' : has_coe (A →+[M] B) (A →[M] B) :=
⟨to_mul_action_hom⟩
instance : has_coe_to_fun (A →+[M] B) :=
⟨_, to_fun⟩
variables {M A B}
@[simp] lemma to_fun_eq_coe (f : A →+[M] B) : f.to_fun = ⇑f := rfl
@[norm_cast] lemma coe_fn_coe (f : A →+[M] B) : ((f : A →+ B) : A → B) = f := rfl
@[norm_cast] lemma coe_fn_coe' (f : A →+[M] B) : ((f : A →[M] B) : A → B) = f := rfl
@[ext] theorem ext : ∀ {f g : A →+[M] B}, (∀ x, f x = g x) → f = g
| ⟨f, _, _, _⟩ ⟨g, _, _, _⟩ H := by { congr' 1 with x, exact H x }
theorem ext_iff {f g : A →+[M] B} : f = g ↔ ∀ x, f x = g x :=
⟨λ H x, by rw H, ext⟩
protected lemma congr_fun {f g : A →+[M] B} (h : f = g) (x : A) : f x = g x := h ▸ rfl
lemma to_mul_action_hom_injective {f g : A →+[M] B}
(h : (f : A →[M] B) = (g : A →[M] B)) : f = g :=
by { ext a, exact mul_action_hom.congr_fun h a, }
lemma to_add_monoid_hom_injective {f g : A →+[M] B}
(h : (f : A →+ B) = (g : A →+ B)) : f = g :=
by { ext a, exact add_monoid_hom.congr_fun h a, }
@[simp] lemma map_zero (f : A →+[M] B) : f 0 = 0 :=
f.map_zero'
@[simp] lemma map_add (f : A →+[M] B) (x y : A) : f (x + y) = f x + f y :=
f.map_add' x y
@[simp] lemma map_neg (f : A' →+[M] B') (x : A') : f (-x) = -f x :=
(f : A' →+ B').map_neg x
@[simp] lemma map_sub (f : A' →+[M] B') (x y : A') : f (x - y) = f x - f y :=
(f : A' →+ B').map_sub x y
@[simp] lemma map_smul (f : A →+[M] B) (m : M) (x : A) : f (m • x) = m • f x :=
f.map_smul' m x
variables (M) {A}
/-- The identity map as an equivariant additive monoid homomorphism. -/
protected def id : A →+[M] A :=
⟨id, λ _ _, rfl, rfl, λ _ _, rfl⟩
@[simp] lemma id_apply (x : A) : distrib_mul_action_hom.id M x = x := rfl
variables {M A B C}
instance : has_zero (A →+[M] B) :=
⟨{ map_smul' := by simp,
.. (0 : A →+ B) }⟩
instance : has_one (A →+[M] A) := ⟨distrib_mul_action_hom.id M⟩
@[simp] lemma coe_zero : ((0 : A →+[M] B) : A → B) = 0 := rfl
@[simp] lemma coe_one : ((1 : A →+[M] A) : A → A) = id := rfl
lemma zero_apply (a : A) : (0 : A →+[M] B) a = 0 := rfl
lemma one_apply (a : A) : (1 : A →+[M] A) a = a := rfl
instance : inhabited (A →+[M] B) := ⟨0⟩
/-- Composition of two equivariant additive monoid homomorphisms. -/
def comp (g : B →+[M] C) (f : A →+[M] B) : A →+[M] C :=
{ .. mul_action_hom.comp (g : B →[M] C) (f : A →[M] B),
.. add_monoid_hom.comp (g : B →+ C) (f : A →+ B), }
@[simp] lemma comp_apply (g : B →+[M] C) (f : A →+[M] B) (x : A) : g.comp f x = g (f x) := rfl
@[simp] lemma id_comp (f : A →+[M] B) : (distrib_mul_action_hom.id M).comp f = f :=
ext $ λ x, by rw [comp_apply, id_apply]
@[simp] lemma comp_id (f : A →+[M] B) : f.comp (distrib_mul_action_hom.id M) = f :=
ext $ λ x, by rw [comp_apply, id_apply]
/-- The inverse of a bijective `distrib_mul_action_hom` is a `distrib_mul_action_hom`. -/
@[simps] def inverse (f : A →+[M] B) (g : B → A)
(h₁ : function.left_inverse g f) (h₂ : function.right_inverse g f) :
B →+[M] A :=
{ to_fun := g,
.. (f : A →+ B).inverse g h₁ h₂,
.. (f : A →[M] B).inverse g h₁ h₂ }
section semiring
variables {R M'} [add_monoid M'] [distrib_mul_action R M']
@[ext] lemma ext_ring
{f g : R →+[R] M'} (h : f 1 = g 1) : f = g :=
by { ext x, rw [← mul_one x, ← smul_eq_mul R, f.map_smul, g.map_smul, h], }
lemma ext_ring_iff {f g : R →+[R] M'} : f = g ↔ f 1 = g 1 :=
⟨λ h, h ▸ rfl, ext_ring⟩
end semiring
end distrib_mul_action_hom
/-- Equivariant ring homomorphisms. -/
@[nolint has_inhabited_instance]
structure mul_semiring_action_hom extends R →+[M] S, R →+* S.
/-- Reinterpret an equivariant ring homomorphism as a ring homomorphism. -/
add_decl_doc mul_semiring_action_hom.to_ring_hom
/-- Reinterpret an equivariant ring homomorphism as an equivariant additive monoid homomorphism. -/
add_decl_doc mul_semiring_action_hom.to_distrib_mul_action_hom
notation R ` →+*[`:25 M:25 `] `:0 S:0 := mul_semiring_action_hom M R S
namespace mul_semiring_action_hom
instance has_coe : has_coe (R →+*[M] S) (R →+* S) :=
⟨to_ring_hom⟩
instance has_coe' : has_coe (R →+*[M] S) (R →+[M] S) :=
⟨to_distrib_mul_action_hom⟩
instance : has_coe_to_fun (R →+*[M] S) :=
⟨_, λ c, c.to_fun⟩
variables {M R S}
@[norm_cast] lemma coe_fn_coe (f : R →+*[M] S) : ((f : R →+* S) : R → S) = f := rfl
@[norm_cast] lemma coe_fn_coe' (f : R →+*[M] S) : ((f : R →+[M] S) : R → S) = f := rfl
@[ext] theorem ext : ∀ {f g : R →+*[M] S}, (∀ x, f x = g x) → f = g
| ⟨f, _, _, _, _, _⟩ ⟨g, _, _, _, _, _⟩ H := by { congr' 1 with x, exact H x }
theorem ext_iff {f g : R →+*[M] S} : f = g ↔ ∀ x, f x = g x :=
⟨λ H x, by rw H, ext⟩
@[simp] lemma map_zero (f : R →+*[M] S) : f 0 = 0 :=
f.map_zero'
@[simp] lemma map_add (f : R →+*[M] S) (x y : R) : f (x + y) = f x + f y :=
f.map_add' x y
@[simp] lemma map_neg (f : R' →+*[M] S') (x : R') : f (-x) = -f x :=
(f : R' →+* S').map_neg x
@[simp] lemma map_sub (f : R' →+*[M] S') (x y : R') : f (x - y) = f x - f y :=
(f : R' →+* S').map_sub x y
@[simp] lemma map_one (f : R →+*[M] S) : f 1 = 1 :=
f.map_one'
@[simp] lemma map_mul (f : R →+*[M] S) (x y : R) : f (x * y) = f x * f y :=
f.map_mul' x y
@[simp] lemma map_smul (f : R →+*[M] S) (m : M) (x : R) : f (m • x) = m • f x :=
f.map_smul' m x
variables (M) {R}
/-- The identity map as an equivariant ring homomorphism. -/
protected def id : R →+*[M] R :=
⟨id, λ _ _, rfl, rfl, λ _ _, rfl, rfl, λ _ _, rfl⟩
@[simp] lemma id_apply (x : R) : mul_semiring_action_hom.id M x = x := rfl
variables {M R S T}
/-- Composition of two equivariant additive monoid homomorphisms. -/
def comp (g : S →+*[M] T) (f : R →+*[M] S) : R →+*[M] T :=
{ .. distrib_mul_action_hom.comp (g : S →+[M] T) (f : R →+[M] S),
.. ring_hom.comp (g : S →+* T) (f : R →+* S), }
@[simp] lemma comp_apply (g : S →+*[M] T) (f : R →+*[M] S) (x : R) : g.comp f x = g (f x) := rfl
@[simp] lemma id_comp (f : R →+*[M] S) : (mul_semiring_action_hom.id M).comp f = f :=
ext $ λ x, by rw [comp_apply, id_apply]
@[simp] lemma comp_id (f : R →+*[M] S) : f.comp (mul_semiring_action_hom.id M) = f :=
ext $ λ x, by rw [comp_apply, id_apply]
end mul_semiring_action_hom
section
variables (M) {R'} (U : set R') [is_subring U] [is_invariant_subring M U]
local attribute [instance] subset.ring
/-- The canonical inclusion from an invariant subring. -/
def is_invariant_subring.subtype_hom : U →+*[M] R' :=
{ map_smul' := λ m s, rfl, .. is_subring.subtype U }
@[simp] theorem is_invariant_subring.coe_subtype_hom :
(is_invariant_subring.subtype_hom M U : U → R') = coe := rfl
@[simp] theorem is_invariant_subring.coe_subtype_hom' :
(is_invariant_subring.subtype_hom M U : U →+* R') = is_subring.subtype U := rfl
end
|
7b7b92986ea10fdd8df34cce409275e2e5eddbce | 57c233acf9386e610d99ed20ef139c5f97504ba3 | /src/measure_theory/measure/haar_lebesgue.lean | c243f6984cbccf92d0cb80818c46a50e772378ac | [
"Apache-2.0"
] | permissive | robertylewis/mathlib | 3d16e3e6daf5ddde182473e03a1b601d2810952c | 1d13f5b932f5e40a8308e3840f96fc882fae01f0 | refs/heads/master | 1,651,379,945,369 | 1,644,276,960,000 | 1,644,276,960,000 | 98,875,504 | 0 | 0 | Apache-2.0 | 1,644,253,514,000 | 1,501,495,700,000 | Lean | UTF-8 | Lean | false | false | 39,068 | lean | /-
Copyright (c) 2021 Floris van Doorn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Floris van Doorn, Sébastien Gouëzel
-/
import measure_theory.measure.lebesgue
import measure_theory.measure.haar
import linear_algebra.finite_dimensional
import analysis.normed_space.pointwise
import measure_theory.group.pointwise
/-!
# Relationship between the Haar and Lebesgue measures
We prove that the Haar measure and Lebesgue measure are equal on `ℝ` and on `ℝ^ι`, in
`measure_theory.add_haar_measure_eq_volume` and `measure_theory.add_haar_measure_eq_volume_pi`.
We deduce basic properties of any Haar measure on a finite dimensional real vector space:
* `map_linear_map_add_haar_eq_smul_add_haar`: a linear map rescales the Haar measure by the
absolute value of its determinant.
* `add_haar_preimage_linear_map` : when `f` is a linear map with nonzero determinant, the measure
of `f ⁻¹' s` is the measure of `s` multiplied by the absolute value of the inverse of the
determinant of `f`.
* `add_haar_image_linear_map` : when `f` is a linear map, the measure of `f '' s` is the
measure of `s` multiplied by the absolute value of the determinant of `f`.
* `add_haar_submodule` : a strict submodule has measure `0`.
* `add_haar_smul` : the measure of `r • s` is `|r| ^ dim * μ s`.
* `add_haar_ball`: the measure of `ball x r` is `r ^ dim * μ (ball 0 1)`.
* `add_haar_closed_ball`: the measure of `closed_ball x r` is `r ^ dim * μ (ball 0 1)`.
* `add_haar_sphere`: spheres have zero measure.
We also show that a Lebesgue density point `x` of a set `s` (with respect to closed balls) has
density one for the rescaled copies `{x} + r • t` of a given set `t` with positive measure, in
`tendsto_add_haar_inter_smul_one_of_density_one`. In particular, `s` intersects `{x} + r • t` for
small `r`, see `eventually_nonempty_inter_smul_of_density_one`.
-/
open topological_space set filter metric
open_locale ennreal pointwise topological_space
/-- The interval `[0,1]` as a compact set with non-empty interior. -/
def topological_space.positive_compacts.Icc01 : positive_compacts ℝ :=
⟨Icc 0 1, is_compact_Icc, by simp_rw [interior_Icc, nonempty_Ioo, zero_lt_one]⟩
universe u
/-- The set `[0,1]^ι` as a compact set with non-empty interior. -/
def topological_space.positive_compacts.pi_Icc01 (ι : Type*) [fintype ι] :
positive_compacts (ι → ℝ) :=
⟨set.pi set.univ (λ i, Icc 0 1), is_compact_univ_pi (λ i, is_compact_Icc),
by simp only [interior_pi_set, finite.of_fintype, interior_Icc, univ_pi_nonempty_iff, nonempty_Ioo,
implies_true_iff, zero_lt_one]⟩
namespace measure_theory
open measure topological_space.positive_compacts finite_dimensional
/-!
### The Lebesgue measure is a Haar measure on `ℝ` and on `ℝ^ι`.
-/
instance is_add_left_invariant_real_volume :
is_add_left_invariant (volume : measure ℝ) :=
⟨by simp [real.map_volume_add_left]⟩
/-- The Haar measure equals the Lebesgue measure on `ℝ`. -/
lemma add_haar_measure_eq_volume : add_haar_measure Icc01 = volume :=
by { convert (add_haar_measure_unique volume Icc01).symm, simp [Icc01] }
instance : is_add_haar_measure (volume : measure ℝ) :=
by { rw ← add_haar_measure_eq_volume, apply_instance }
instance is_add_left_invariant_real_volume_pi (ι : Type*) [fintype ι] :
is_add_left_invariant (volume : measure (ι → ℝ)) :=
⟨by simp [real.map_volume_pi_add_left]⟩
/-- The Haar measure equals the Lebesgue measure on `ℝ^ι`. -/
lemma add_haar_measure_eq_volume_pi (ι : Type*) [fintype ι] :
add_haar_measure (pi_Icc01 ι) = volume :=
begin
convert (add_haar_measure_unique volume (pi_Icc01 ι)).symm,
simp only [pi_Icc01, volume_pi_pi (λ i, Icc (0 : ℝ) 1),
finset.prod_const_one, ennreal.of_real_one, real.volume_Icc, one_smul, sub_zero]
end
instance is_add_haar_measure_volume_pi (ι : Type*) [fintype ι] :
is_add_haar_measure (volume : measure (ι → ℝ)) :=
by { rw ← add_haar_measure_eq_volume_pi, apply_instance }
namespace measure
/-!
### Strict subspaces have zero measure
-/
/-- If a set is disjoint of its translates by infinitely many bounded vectors, then it has measure
zero. This auxiliary lemma proves this assuming additionally that the set is bounded. -/
lemma add_haar_eq_zero_of_disjoint_translates_aux
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
{s : set E} (u : ℕ → E) (sb : bounded s) (hu : bounded (range u))
(hs : pairwise (disjoint on (λ n, {u n} + s))) (h's : measurable_set s) :
μ s = 0 :=
begin
by_contra h,
apply lt_irrefl ∞,
calc
∞ = ∑' (n : ℕ), μ s : (ennreal.tsum_const_eq_top_of_ne_zero h).symm
... = ∑' (n : ℕ), μ ({u n} + s) :
by { congr' 1, ext1 n, simp only [image_add_left, measure_preimage_add, singleton_add] }
... = μ (⋃ n, {u n} + s) :
by rw measure_Union hs
(λ n, by simpa only [image_add_left, singleton_add] using measurable_id.const_add _ h's)
... = μ (range u + s) : by rw [← Union_add, Union_singleton_eq_range]
... < ∞ : bounded.measure_lt_top (hu.add sb)
end
/-- If a set is disjoint of its translates by infinitely many bounded vectors, then it has measure
zero. -/
lemma add_haar_eq_zero_of_disjoint_translates
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
{s : set E} (u : ℕ → E) (hu : bounded (range u))
(hs : pairwise (disjoint on (λ n, {u n} + s))) (h's : measurable_set s) :
μ s = 0 :=
begin
suffices H : ∀ R, μ (s ∩ closed_ball 0 R) = 0,
{ apply le_antisymm _ (zero_le _),
calc μ s ≤ ∑' (n : ℕ), μ (s ∩ closed_ball 0 n) :
by { conv_lhs { rw ← Union_inter_closed_ball_nat s 0 }, exact measure_Union_le _ }
... = 0 : by simp only [H, tsum_zero] },
assume R,
apply add_haar_eq_zero_of_disjoint_translates_aux μ u
(bounded.mono (inter_subset_right _ _) bounded_closed_ball) hu _
(h's.inter (measurable_set_closed_ball)),
apply pairwise_disjoint.mono hs (λ n, _),
exact add_subset_add (subset.refl _) (inter_subset_left _ _)
end
/-- A strict vector subspace has measure zero. -/
lemma add_haar_submodule
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
(s : submodule ℝ E) (hs : s ≠ ⊤) : μ s = 0 :=
begin
obtain ⟨x, hx⟩ : ∃ x, x ∉ s,
by simpa only [submodule.eq_top_iff', not_exists, ne.def, not_forall] using hs,
obtain ⟨c, cpos, cone⟩ : ∃ (c : ℝ), 0 < c ∧ c < 1 := ⟨1/2, by norm_num, by norm_num⟩,
have A : bounded (range (λ (n : ℕ), (c ^ n) • x)),
{ have : tendsto (λ (n : ℕ), (c ^ n) • x) at_top (𝓝 ((0 : ℝ) • x)) :=
(tendsto_pow_at_top_nhds_0_of_lt_1 cpos.le cone).smul_const x,
exact bounded_range_of_tendsto _ this },
apply add_haar_eq_zero_of_disjoint_translates μ _ A _
(submodule.closed_of_finite_dimensional s).measurable_set,
assume m n hmn,
simp only [function.on_fun, image_add_left, singleton_add, disjoint_left, mem_preimage,
set_like.mem_coe],
assume y hym hyn,
have A : (c ^ n - c ^ m) • x ∈ s,
{ convert s.sub_mem hym hyn,
simp only [sub_smul, neg_sub_neg, add_sub_add_right_eq_sub] },
have H : c ^ n - c ^ m ≠ 0,
by simpa only [sub_eq_zero, ne.def] using (strict_anti_pow cpos cone).injective.ne hmn.symm,
have : x ∈ s,
{ convert s.smul_mem (c ^ n - c ^ m)⁻¹ A,
rw [smul_smul, inv_mul_cancel H, one_smul] },
exact hx this
end
/-!
### Applying a linear map rescales Haar measure by the determinant
We first prove this on `ι → ℝ`, using that this is already known for the product Lebesgue
measure (thanks to matrices computations). Then, we extend this to any finite-dimensional real
vector space by using a linear equiv with a space of the form `ι → ℝ`, and arguing that such a
linear equiv maps Haar measure to Haar measure.
-/
lemma map_linear_map_add_haar_pi_eq_smul_add_haar
{ι : Type*} [fintype ι] {f : (ι → ℝ) →ₗ[ℝ] (ι → ℝ)} (hf : f.det ≠ 0)
(μ : measure (ι → ℝ)) [is_add_haar_measure μ] :
measure.map f μ = ennreal.of_real (abs (f.det)⁻¹) • μ :=
begin
/- We have already proved the result for the Lebesgue product measure, using matrices.
We deduce it for any Haar measure by uniqueness (up to scalar multiplication). -/
have := add_haar_measure_unique μ (pi_Icc01 ι),
rw this,
simp [add_haar_measure_eq_volume_pi, real.map_linear_map_volume_pi_eq_smul_volume_pi hf,
smul_smul, mul_comm],
end
lemma map_linear_map_add_haar_eq_smul_add_haar
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
{f : E →ₗ[ℝ] E} (hf : f.det ≠ 0) :
measure.map f μ = ennreal.of_real (abs (f.det)⁻¹) • μ :=
begin
-- we reduce to the case of `E = ι → ℝ`, for which we have already proved the result using
-- matrices in `map_linear_map_add_haar_pi_eq_smul_add_haar`.
let ι := fin (finrank ℝ E),
haveI : finite_dimensional ℝ (ι → ℝ) := by apply_instance,
have : finrank ℝ E = finrank ℝ (ι → ℝ), by simp,
have e : E ≃ₗ[ℝ] ι → ℝ := linear_equiv.of_finrank_eq E (ι → ℝ) this,
-- next line is to avoid `g` getting reduced by `simp`.
obtain ⟨g, hg⟩ : ∃ g, g = (e : E →ₗ[ℝ] (ι → ℝ)).comp (f.comp (e.symm : (ι → ℝ) →ₗ[ℝ] E)) :=
⟨_, rfl⟩,
have gdet : g.det = f.det, by { rw [hg], exact linear_map.det_conj f e },
rw ← gdet at hf ⊢,
have fg : f = (e.symm : (ι → ℝ) →ₗ[ℝ] E).comp (g.comp (e : E →ₗ[ℝ] (ι → ℝ))),
{ ext x,
simp only [linear_equiv.coe_coe, function.comp_app, linear_map.coe_comp,
linear_equiv.symm_apply_apply, hg] },
simp only [fg, linear_equiv.coe_coe, linear_map.coe_comp],
have Ce : continuous e := (e : E →ₗ[ℝ] (ι → ℝ)).continuous_of_finite_dimensional,
have Cg : continuous g := linear_map.continuous_of_finite_dimensional g,
have Cesymm : continuous e.symm := (e.symm : (ι → ℝ) →ₗ[ℝ] E).continuous_of_finite_dimensional,
rw [← map_map Cesymm.measurable (Cg.comp Ce).measurable, ← map_map Cg.measurable Ce.measurable],
haveI : is_add_haar_measure (map e μ) := is_add_haar_measure_map μ e.to_add_equiv Ce Cesymm,
have ecomp : (e.symm) ∘ e = id,
by { ext x, simp only [id.def, function.comp_app, linear_equiv.symm_apply_apply] },
rw [map_linear_map_add_haar_pi_eq_smul_add_haar hf (map e μ), linear_map.map_smul,
map_map Cesymm.measurable Ce.measurable, ecomp, measure.map_id]
end
/-- The preimage of a set `s` under a linear map `f` with nonzero determinant has measure
equal to `μ s` times the absolute value of the inverse of the determinant of `f`. -/
@[simp] lemma add_haar_preimage_linear_map
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
{f : E →ₗ[ℝ] E} (hf : f.det ≠ 0) (s : set E) :
μ (f ⁻¹' s) = ennreal.of_real (abs (f.det)⁻¹) * μ s :=
calc μ (f ⁻¹' s) = measure.map f μ s :
((f.equiv_of_det_ne_zero hf).to_continuous_linear_equiv.to_homeomorph
.to_measurable_equiv.map_apply s).symm
... = ennreal.of_real (abs (f.det)⁻¹) * μ s :
by { rw map_linear_map_add_haar_eq_smul_add_haar μ hf, refl }
/-- The preimage of a set `s` under a continuous linear map `f` with nonzero determinant has measure
equal to `μ s` times the absolute value of the inverse of the determinant of `f`. -/
@[simp] lemma add_haar_preimage_continuous_linear_map
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
{f : E →L[ℝ] E} (hf : linear_map.det (f : E →ₗ[ℝ] E) ≠ 0) (s : set E) :
μ (f ⁻¹' s) = ennreal.of_real (abs (linear_map.det (f : E →ₗ[ℝ] E))⁻¹) * μ s :=
add_haar_preimage_linear_map μ hf s
/-- The preimage of a set `s` under a linear equiv `f` has measure
equal to `μ s` times the absolute value of the inverse of the determinant of `f`. -/
@[simp] lemma add_haar_preimage_linear_equiv
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
(f : E ≃ₗ[ℝ] E) (s : set E) :
μ (f ⁻¹' s) = ennreal.of_real (abs (f.symm : E →ₗ[ℝ] E).det) * μ s :=
begin
have A : (f : E →ₗ[ℝ] E).det ≠ 0 := (linear_equiv.is_unit_det' f).ne_zero,
convert add_haar_preimage_linear_map μ A s,
simp only [linear_equiv.det_coe_symm]
end
/-- The preimage of a set `s` under a continuous linear equiv `f` has measure
equal to `μ s` times the absolute value of the inverse of the determinant of `f`. -/
@[simp] lemma add_haar_preimage_continuous_linear_equiv
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
(f : E ≃L[ℝ] E) (s : set E) :
μ (f ⁻¹' s) = ennreal.of_real (abs (f.symm : E →ₗ[ℝ] E).det) * μ s :=
add_haar_preimage_linear_equiv μ _ s
/-- The image of a set `s` under a linear map `f` has measure
equal to `μ s` times the absolute value of the determinant of `f`. -/
@[simp] lemma add_haar_image_linear_map
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
(f : E →ₗ[ℝ] E) (s : set E) :
μ (f '' s) = ennreal.of_real (abs f.det) * μ s :=
begin
rcases ne_or_eq f.det 0 with hf|hf,
{ let g := (f.equiv_of_det_ne_zero hf).to_continuous_linear_equiv,
change μ (g '' s) = _,
rw [continuous_linear_equiv.image_eq_preimage g s, add_haar_preimage_continuous_linear_equiv],
congr,
ext x,
simp only [linear_equiv.coe_to_continuous_linear_equiv, linear_equiv.of_is_unit_det_apply,
linear_equiv.coe_coe, continuous_linear_equiv.symm_symm], },
{ simp only [hf, zero_mul, ennreal.of_real_zero, abs_zero],
have : μ f.range = 0 :=
add_haar_submodule μ _ (linear_map.range_lt_top_of_det_eq_zero hf).ne,
exact le_antisymm (le_trans (measure_mono (image_subset_range _ _)) this.le) (zero_le _) }
end
/-- The image of a set `s` under a continuous linear map `f` has measure
equal to `μ s` times the absolute value of the determinant of `f`. -/
@[simp] lemma add_haar_image_continuous_linear_map
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
(f : E →L[ℝ] E) (s : set E) :
μ (f '' s) = ennreal.of_real (abs (f : E →ₗ[ℝ] E).det) * μ s :=
add_haar_image_linear_map μ _ s
/-- The image of a set `s` under a continuous linear equiv `f` has measure
equal to `μ s` times the absolute value of the determinant of `f`. -/
@[simp] lemma add_haar_image_continuous_linear_equiv
{E : Type*} [normed_group E] [normed_space ℝ E] [measurable_space E] [borel_space E]
[finite_dimensional ℝ E] (μ : measure E) [is_add_haar_measure μ]
(f : E ≃L[ℝ] E) (s : set E) :
μ (f '' s) = ennreal.of_real (abs (f : E →ₗ[ℝ] E).det) * μ s :=
add_haar_image_linear_map μ _ s
/-!
### Basic properties of Haar measures on real vector spaces
-/
variables {E : Type*} [normed_group E] [measurable_space E] [normed_space ℝ E]
[finite_dimensional ℝ E] [borel_space E] (μ : measure E) [is_add_haar_measure μ]
lemma map_add_haar_smul {r : ℝ} (hr : r ≠ 0) :
measure.map ((•) r) μ = ennreal.of_real (abs (r ^ (finrank ℝ E))⁻¹) • μ :=
begin
let f : E →ₗ[ℝ] E := r • 1,
change measure.map f μ = _,
have hf : f.det ≠ 0,
{ simp only [mul_one, linear_map.det_smul, ne.def, monoid_hom.map_one],
assume h,
exact hr (pow_eq_zero h) },
simp only [map_linear_map_add_haar_eq_smul_add_haar μ hf, mul_one, linear_map.det_smul,
monoid_hom.map_one],
end
@[simp] lemma add_haar_preimage_smul {r : ℝ} (hr : r ≠ 0) (s : set E) :
μ (((•) r) ⁻¹' s) = ennreal.of_real (abs (r ^ (finrank ℝ E))⁻¹) * μ s :=
calc μ (((•) r) ⁻¹' s) = measure.map ((•) r) μ s :
((homeomorph.smul (is_unit_iff_ne_zero.2 hr).unit).to_measurable_equiv.map_apply s).symm
... = ennreal.of_real (abs (r^(finrank ℝ E))⁻¹) * μ s : by { rw map_add_haar_smul μ hr, refl }
/-- Rescaling a set by a factor `r` multiplies its measure by `abs (r ^ dim)`. -/
@[simp] lemma add_haar_smul (r : ℝ) (s : set E) :
μ (r • s) = ennreal.of_real (abs (r ^ (finrank ℝ E))) * μ s :=
begin
rcases ne_or_eq r 0 with h|rfl,
{ rw [← preimage_smul_inv₀ h, add_haar_preimage_smul μ (inv_ne_zero h), inv_pow₀, inv_inv₀] },
rcases eq_empty_or_nonempty s with rfl|hs,
{ simp only [measure_empty, mul_zero, smul_set_empty] },
rw [zero_smul_set hs, ← singleton_zero],
by_cases h : finrank ℝ E = 0,
{ haveI : subsingleton E := finrank_zero_iff.1 h,
simp only [h, one_mul, ennreal.of_real_one, abs_one, subsingleton.eq_univ_of_nonempty hs,
pow_zero, subsingleton.eq_univ_of_nonempty (singleton_nonempty (0 : E))] },
{ haveI : nontrivial E := nontrivial_of_finrank_pos (bot_lt_iff_ne_bot.2 h),
simp only [h, zero_mul, ennreal.of_real_zero, abs_zero, ne.def, not_false_iff, zero_pow',
measure_singleton] }
end
/-! We don't need to state `map_add_haar_neg` here, because it has already been proved for
general Haar measures on general commutative groups. -/
/-! ### Measure of balls -/
lemma add_haar_ball_center
{E : Type*} [normed_group E] [measurable_space E]
[borel_space E] (μ : measure E) [is_add_haar_measure μ] (x : E) (r : ℝ) :
μ (ball x r) = μ (ball (0 : E) r) :=
begin
have : ball (0 : E) r = ((+) x) ⁻¹' (ball x r), by simp [preimage_add_ball],
rw [this, measure_preimage_add]
end
lemma add_haar_closed_ball_center
{E : Type*} [normed_group E] [measurable_space E]
[borel_space E] (μ : measure E) [is_add_haar_measure μ] (x : E) (r : ℝ) :
μ (closed_ball x r) = μ (closed_ball (0 : E) r) :=
begin
have : closed_ball (0 : E) r = ((+) x) ⁻¹' (closed_ball x r), by simp [preimage_add_closed_ball],
rw [this, measure_preimage_add]
end
lemma add_haar_ball_mul_of_pos (x : E) {r : ℝ} (hr : 0 < r) (s : ℝ) :
μ (ball x (r * s)) = ennreal.of_real (r ^ (finrank ℝ E)) * μ (ball 0 s) :=
begin
have : ball (0 : E) (r * s) = r • ball 0 s,
by simp only [smul_ball hr.ne' (0 : E) s, real.norm_eq_abs, abs_of_nonneg hr.le, smul_zero],
simp only [this, add_haar_smul, abs_of_nonneg hr.le, add_haar_ball_center, abs_pow],
end
lemma add_haar_ball_of_pos (x : E) {r : ℝ} (hr : 0 < r) :
μ (ball x r) = ennreal.of_real (r ^ (finrank ℝ E)) * μ (ball 0 1) :=
by rw [← add_haar_ball_mul_of_pos μ x hr, mul_one]
lemma add_haar_ball_mul [nontrivial E] (x : E) {r : ℝ} (hr : 0 ≤ r) (s : ℝ) :
μ (ball x (r * s)) = ennreal.of_real (r ^ (finrank ℝ E)) * μ (ball 0 s) :=
begin
rcases has_le.le.eq_or_lt hr with h|h,
{ simp only [← h, zero_pow finrank_pos, measure_empty, zero_mul, ennreal.of_real_zero,
ball_zero] },
{ exact add_haar_ball_mul_of_pos μ x h s }
end
lemma add_haar_ball [nontrivial E] (x : E) {r : ℝ} (hr : 0 ≤ r) :
μ (ball x r) = ennreal.of_real (r ^ (finrank ℝ E)) * μ (ball 0 1) :=
by rw [← add_haar_ball_mul μ x hr, mul_one]
lemma add_haar_closed_ball_mul_of_pos (x : E) {r : ℝ} (hr : 0 < r) (s : ℝ) :
μ (closed_ball x (r * s)) = ennreal.of_real (r ^ (finrank ℝ E)) * μ (closed_ball 0 s) :=
begin
have : closed_ball (0 : E) (r * s) = r • closed_ball 0 s,
by simp [smul_closed_ball' hr.ne' (0 : E), real.norm_eq_abs, abs_of_nonneg hr.le],
simp only [this, add_haar_smul, abs_of_nonneg hr.le, add_haar_closed_ball_center, abs_pow],
end
lemma add_haar_closed_ball_mul (x : E) {r : ℝ} (hr : 0 ≤ r) {s : ℝ} (hs : 0 ≤ s) :
μ (closed_ball x (r * s)) = ennreal.of_real (r ^ (finrank ℝ E)) * μ (closed_ball 0 s) :=
begin
have : closed_ball (0 : E) (r * s) = r • closed_ball 0 s,
by simp [smul_closed_ball r (0 : E) hs, real.norm_eq_abs, abs_of_nonneg hr],
simp only [this, add_haar_smul, abs_of_nonneg hr, add_haar_closed_ball_center, abs_pow],
end
/-- The measure of a closed ball can be expressed in terms of the measure of the closed unit ball.
Use instead `add_haar_closed_ball`, which uses the measure of the open unit ball as a standard
form. -/
lemma add_haar_closed_ball' (x : E) {r : ℝ} (hr : 0 ≤ r) :
μ (closed_ball x r) = ennreal.of_real (r ^ (finrank ℝ E)) * μ (closed_ball 0 1) :=
by rw [← add_haar_closed_ball_mul μ x hr zero_le_one, mul_one]
lemma add_haar_closed_unit_ball_eq_add_haar_unit_ball :
μ (closed_ball (0 : E) 1) = μ (ball 0 1) :=
begin
apply le_antisymm _ (measure_mono ball_subset_closed_ball),
have A : tendsto (λ (r : ℝ), ennreal.of_real (r ^ (finrank ℝ E)) * μ (closed_ball (0 : E) 1))
(𝓝[<] 1) (𝓝 (ennreal.of_real (1 ^ (finrank ℝ E)) * μ (closed_ball (0 : E) 1))),
{ refine ennreal.tendsto.mul _ (by simp) tendsto_const_nhds (by simp),
exact ennreal.tendsto_of_real ((tendsto_id' nhds_within_le_nhds).pow _) },
simp only [one_pow, one_mul, ennreal.of_real_one] at A,
refine le_of_tendsto A _,
refine mem_nhds_within_Iio_iff_exists_Ioo_subset.2 ⟨(0 : ℝ), by simp, λ r hr, _⟩,
dsimp,
rw ← add_haar_closed_ball' μ (0 : E) hr.1.le,
exact measure_mono (closed_ball_subset_ball hr.2)
end
lemma add_haar_closed_ball (x : E) {r : ℝ} (hr : 0 ≤ r) :
μ (closed_ball x r) = ennreal.of_real (r ^ (finrank ℝ E)) * μ (ball 0 1) :=
by rw [add_haar_closed_ball' μ x hr, add_haar_closed_unit_ball_eq_add_haar_unit_ball]
lemma add_haar_sphere_of_ne_zero (x : E) {r : ℝ} (hr : r ≠ 0) :
μ (sphere x r) = 0 :=
begin
rcases hr.lt_or_lt with h|h,
{ simp only [empty_diff, measure_empty, ← closed_ball_diff_ball, closed_ball_eq_empty.2 h] },
{ rw [← closed_ball_diff_ball,
measure_diff ball_subset_closed_ball measurable_set_ball measure_ball_lt_top.ne,
add_haar_ball_of_pos μ _ h, add_haar_closed_ball μ _ h.le, tsub_self];
apply_instance }
end
lemma add_haar_sphere [nontrivial E] (x : E) (r : ℝ) :
μ (sphere x r) = 0 :=
begin
rcases eq_or_ne r 0 with rfl|h,
{ rw [sphere_zero, measure_singleton] },
{ exact add_haar_sphere_of_ne_zero μ x h }
end
lemma add_haar_singleton_add_smul_div_singleton_add_smul
{r : ℝ} (hr : r ≠ 0) (x y : E) (s t : set E) :
μ ({x} + r • s) / μ ({y} + r • t) = μ s / μ t :=
calc
μ ({x} + r • s) / μ ({y} + r • t)
= ennreal.of_real (|r| ^ finrank ℝ E) * μ s * (ennreal.of_real (|r| ^ finrank ℝ E) * μ t)⁻¹ :
by simp only [div_eq_mul_inv, add_haar_smul, image_add_left, measure_preimage_add, abs_pow,
singleton_add]
... = ennreal.of_real (|r| ^ finrank ℝ E) * (ennreal.of_real (|r| ^ finrank ℝ E))⁻¹ *
(μ s * (μ t)⁻¹) :
begin
rw ennreal.mul_inv,
{ ring },
{ simp only [pow_pos (abs_pos.mpr hr), ennreal.of_real_eq_zero, not_le, ne.def, true_or] },
{ simp only [ennreal.of_real_ne_top, true_or, ne.def, not_false_iff] },
end
... = μ s / μ t :
begin
rw [ennreal.mul_inv_cancel, one_mul, div_eq_mul_inv],
{ simp only [pow_pos (abs_pos.mpr hr), ennreal.of_real_eq_zero, not_le, ne.def], },
{ simp only [ennreal.of_real_ne_top, ne.def, not_false_iff] }
end
/-!
### Density points
Besicovitch covering theorem ensures that, for any locally finite measure on a finite-dimensional
real vector space, almost every point of a set `s` is a density point, i.e.,
`μ (s ∩ closed_ball x r) / μ (closed_ball x r)` tends to `1` as `r` tends to `0`
(see `besicovitch.ae_tendsto_measure_inter_div`).
When `μ` is a Haar measure, one can deduce the same property for any rescaling sequence of sets,
of the form `{x} + r • t` where `t` is a set with positive finite measure, instead of the sequence
of closed balls.
We argue first for the dual property, i.e., if `s` has density `0` at `x`, then
`μ (s ∩ ({x} + r • t)) / μ ({x} + r • t)` tends to `0`. First when `t` is contained in the ball
of radius `1`, in `tendsto_add_haar_inter_smul_zero_of_density_zero_aux1`,
(by arguing by inclusion). Then when `t` is bounded, reducing to the previous one by rescaling, in
`tendsto_add_haar_inter_smul_zero_of_density_zero_aux2`.
Then for a general set `t`, by cutting it into a bounded part and a part with small measure, in
`tendsto_add_haar_inter_smul_zero_of_density_zero`.
Going to the complement, one obtains the desired property at points of density `1`, first when
`s` is measurable in `tendsto_add_haar_inter_smul_one_of_density_one_aux`, and then without this
assumption in `tendsto_add_haar_inter_smul_one_of_density_one` by applying the previous lemma to
the measurable hull `to_measurable μ s`
-/
lemma tendsto_add_haar_inter_smul_zero_of_density_zero_aux1
(s : set E) (x : E)
(h : tendsto (λ r, μ (s ∩ closed_ball x r) / μ (closed_ball x r)) (𝓝[>] 0) (𝓝 0))
(t : set E) (u : set E) (h'u : μ u ≠ 0) (t_bound : t ⊆ closed_ball 0 1) :
tendsto (λ (r : ℝ), μ (s ∩ ({x} + r • t)) / μ ({x} + r • u)) (𝓝[>] 0) (𝓝 0) :=
begin
have A : tendsto (λ (r : ℝ), μ (s ∩ ({x} + r • t)) / μ (closed_ball x r)) (𝓝[>] 0) (𝓝 0),
{ apply tendsto_of_tendsto_of_tendsto_of_le_of_le' tendsto_const_nhds h
(eventually_of_forall (λ b, zero_le _)),
filter_upwards [self_mem_nhds_within],
rintros r (rpos : 0 < r),
apply ennreal.mul_le_mul (measure_mono (inter_subset_inter_right _ _)) le_rfl,
assume y hy,
have : y - x ∈ r • closed_ball (0 : E) 1,
{ apply smul_set_mono t_bound,
simpa [neg_add_eq_sub] using hy },
simpa only [smul_closed_ball _ _ zero_le_one, real.norm_of_nonneg rpos.le,
mem_closed_ball_iff_norm, mul_one, sub_zero, smul_zero] },
have B : tendsto (λ (r : ℝ), μ (closed_ball x r) / μ ({x} + r • u)) (𝓝[>] 0)
(𝓝 (μ (closed_ball x 1) / μ ({x} + u))),
{ apply tendsto_const_nhds.congr' _,
filter_upwards [self_mem_nhds_within],
rintros r (rpos : 0 < r),
have : closed_ball x r = {x} + r • closed_ball 0 1,
by simp only [smul_closed_ball, real.norm_of_nonneg rpos.le, zero_le_one, add_zero, mul_one,
singleton_add_closed_ball, smul_zero],
simp only [this, add_haar_singleton_add_smul_div_singleton_add_smul μ rpos.ne'],
simp only [add_haar_closed_ball_center, image_add_left, measure_preimage_add, singleton_add] },
have C : tendsto (λ (r : ℝ),
(μ (s ∩ ({x} + r • t)) / μ (closed_ball x r)) * (μ (closed_ball x r) / μ ({x} + r • u)))
(𝓝[>] 0) (𝓝 (0 * (μ (closed_ball x 1) / μ ({x} + u)))),
{ apply ennreal.tendsto.mul A _ B (or.inr ennreal.zero_ne_top),
simp only [ennreal.div_eq_top, h'u, measure_closed_ball_lt_top.ne, false_or, image_add_left,
eq_self_iff_true, not_true, ne.def, not_false_iff, measure_preimage_add, singleton_add,
and_false, false_and] },
simp only [zero_mul] at C,
apply C.congr' _,
filter_upwards [self_mem_nhds_within],
rintros r (rpos : 0 < r),
calc μ (s ∩ ({x} + r • t)) / μ (closed_ball x r) * (μ (closed_ball x r) / μ ({x} + r • u))
= (μ (closed_ball x r) * (μ (closed_ball x r))⁻¹) * (μ (s ∩ ({x} + r • t)) / μ ({x} + r • u)) :
by { simp only [div_eq_mul_inv], ring }
... = μ (s ∩ ({x} + r • t)) / μ ({x} + r • u) :
by rw [ennreal.mul_inv_cancel (measure_closed_ball_pos μ x rpos).ne'
measure_closed_ball_lt_top.ne, one_mul],
end
lemma tendsto_add_haar_inter_smul_zero_of_density_zero_aux2
(s : set E) (x : E)
(h : tendsto (λ r, μ (s ∩ closed_ball x r) / μ (closed_ball x r)) (𝓝[>] 0) (𝓝 0))
(t : set E) (u : set E) (h'u : μ u ≠ 0)
(R : ℝ) (Rpos : 0 < R) (t_bound : t ⊆ closed_ball 0 R) :
tendsto (λ (r : ℝ), μ (s ∩ ({x} + r • t)) / μ ({x} + r • u)) (𝓝[>] 0) (𝓝 0) :=
begin
set t' := R⁻¹ • t with ht',
set u' := R⁻¹ • u with hu',
have A : tendsto (λ (r : ℝ), μ (s ∩ ({x} + r • t')) / μ ({x} + r • u')) (𝓝[>] 0) (𝓝 0),
{ apply tendsto_add_haar_inter_smul_zero_of_density_zero_aux1 μ s x h
t' u',
{ simp only [h'u, (pow_pos Rpos _).ne', abs_nonpos_iff, add_haar_smul, not_false_iff,
ennreal.of_real_eq_zero, inv_eq_zero, inv_pow₀, ne.def, or_self, mul_eq_zero] },
{ convert smul_set_mono t_bound,
rw [smul_closed_ball _ _ Rpos.le, smul_zero, real.norm_of_nonneg (inv_nonneg.2 Rpos.le),
inv_mul_cancel Rpos.ne'] } },
have B : tendsto (λ (r : ℝ), R * r) (𝓝[>] 0) (𝓝[>] (R * 0)),
{ apply tendsto_nhds_within_of_tendsto_nhds_of_eventually_within,
{ exact (tendsto_const_nhds.mul tendsto_id).mono_left nhds_within_le_nhds },
{ filter_upwards [self_mem_nhds_within],
assume r rpos,
rw mul_zero,
exact mul_pos Rpos rpos } },
rw mul_zero at B,
apply (A.comp B).congr' _,
filter_upwards [self_mem_nhds_within],
rintros r (rpos : 0 < r),
have T : (R * r) • t' = r • t,
by rw [mul_comm, ht', smul_smul, mul_assoc, mul_inv_cancel Rpos.ne', mul_one],
have U : (R * r) • u' = r • u,
by rw [mul_comm, hu', smul_smul, mul_assoc, mul_inv_cancel Rpos.ne', mul_one],
dsimp,
rw [T, U],
end
/-- Consider a point `x` at which a set `s` has density zero, with respect to closed balls. Then it
also has density zero with respect to any measurable set `t`: the proportion of points in `s`
belonging to a rescaled copy `{x} + r • t` of `t` tends to zero as `r` tends to zero. -/
lemma tendsto_add_haar_inter_smul_zero_of_density_zero
(s : set E) (x : E)
(h : tendsto (λ r, μ (s ∩ closed_ball x r) / μ (closed_ball x r)) (𝓝[>] 0) (𝓝 0))
(t : set E) (ht : measurable_set t) (h''t : μ t ≠ ∞) :
tendsto (λ (r : ℝ), μ (s ∩ ({x} + r • t)) / μ ({x} + r • t)) (𝓝[>] 0) (𝓝 0) :=
begin
refine tendsto_order.2 ⟨λ a' ha', (ennreal.not_lt_zero ha').elim, λ ε (εpos : 0 < ε), _⟩,
rcases eq_or_ne (μ t) 0 with h't|h't,
{ apply eventually_of_forall (λ r, _),
suffices H : μ (s ∩ ({x} + r • t)) = 0,
by { rw H, simpa only [ennreal.zero_div] using εpos },
apply le_antisymm _ (zero_le _),
calc μ (s ∩ ({x} + r • t)) ≤ μ ({x} + r • t) : measure_mono (inter_subset_right _ _)
... = 0 : by simp only [h't, add_haar_smul, image_add_left, measure_preimage_add,
singleton_add, mul_zero] },
obtain ⟨n, npos, hn⟩ : ∃ (n : ℕ), 0 < n ∧ μ (t \ closed_ball 0 n) < (ε / 2) * μ t,
{ have A : tendsto (λ (n : ℕ), μ (t \ closed_ball 0 n)) at_top
(𝓝 (μ (⋂ (n : ℕ), t \ closed_ball 0 n))),
{ have N : ∃ (n : ℕ), μ (t \ closed_ball 0 n) ≠ ∞ :=
⟨0, ((measure_mono (diff_subset t _)).trans_lt h''t.lt_top).ne⟩,
refine tendsto_measure_Inter (λ n, ht.diff measurable_set_closed_ball) (λ m n hmn, _) N,
exact diff_subset_diff subset.rfl (closed_ball_subset_closed_ball (nat.cast_le.2 hmn)) },
have : (⋂ (n : ℕ), t \ closed_ball 0 n) = ∅,
by simp_rw [diff_eq, ← inter_Inter, Inter_eq_compl_Union_compl, compl_compl,
Union_closed_ball_nat, compl_univ, inter_empty],
simp only [this, measure_empty] at A,
have I : 0 < (ε / 2) * μ t := ennreal.mul_pos (ennreal.half_pos εpos.ne').ne' h't,
exact (eventually.and (Ioi_mem_at_top 0) ((tendsto_order.1 A).2 _ I)).exists },
have L : tendsto (λ (r : ℝ), μ (s ∩ ({x} + r • (t ∩ closed_ball 0 n))) / μ ({x} + r • t))
(𝓝[>] 0) (𝓝 0) :=
tendsto_add_haar_inter_smul_zero_of_density_zero_aux2 μ s x h
_ t h't n (nat.cast_pos.2 npos) (inter_subset_right _ _),
filter_upwards [(tendsto_order.1 L).2 _ (ennreal.half_pos εpos.ne'), self_mem_nhds_within],
rintros r hr (rpos : 0 < r),
have I : μ (s ∩ ({x} + r • t)) ≤
μ (s ∩ ({x} + r • (t ∩ closed_ball 0 n))) + μ ({x} + r • (t \ closed_ball 0 n)) := calc
μ (s ∩ ({x} + r • t))
= μ ((s ∩ ({x} + r • (t ∩ closed_ball 0 n))) ∪ (s ∩ ({x} + r • (t \ closed_ball 0 n)))) :
by rw [← inter_union_distrib_left, ← add_union, ← smul_set_union, inter_union_diff]
... ≤ μ (s ∩ ({x} + r • (t ∩ closed_ball 0 n))) + μ (s ∩ ({x} + r • (t \ closed_ball 0 n))) :
measure_union_le _ _
... ≤ μ (s ∩ ({x} + r • (t ∩ closed_ball 0 n))) + μ ({x} + r • (t \ closed_ball 0 n)) :
add_le_add le_rfl (measure_mono (inter_subset_right _ _)),
calc μ (s ∩ ({x} + r • t)) / μ ({x} + r • t)
≤ (μ (s ∩ ({x} + r • (t ∩ closed_ball 0 n))) + μ ({x} + r • (t \ closed_ball 0 n))) /
μ ({x} + r • t) : ennreal.mul_le_mul I le_rfl
... < ε / 2 + ε / 2 :
begin
rw ennreal.add_div,
apply ennreal.add_lt_add hr _,
rwa [add_haar_singleton_add_smul_div_singleton_add_smul μ rpos.ne',
ennreal.div_lt_iff (or.inl h't) (or.inl h''t)],
end
... = ε : ennreal.add_halves _
end
lemma tendsto_add_haar_inter_smul_one_of_density_one_aux
(s : set E) (hs : measurable_set s) (x : E)
(h : tendsto (λ r, μ (s ∩ closed_ball x r) / μ (closed_ball x r)) (𝓝[>] 0) (𝓝 1))
(t : set E) (ht : measurable_set t) (h't : μ t ≠ 0) (h''t : μ t ≠ ∞) :
tendsto (λ (r : ℝ), μ (s ∩ ({x} + r • t)) / μ ({x} + r • t)) (𝓝[>] 0) (𝓝 1) :=
begin
have I : ∀ u v, μ u ≠ 0 → μ u ≠ ∞ → measurable_set v →
μ u / μ u - μ (vᶜ ∩ u) / μ u = μ (v ∩ u) / μ u,
{ assume u v uzero utop vmeas,
simp_rw [div_eq_mul_inv],
rw ← ennreal.sub_mul, swap,
{ simp only [uzero, ennreal.inv_eq_top, implies_true_iff, ne.def, not_false_iff] },
congr' 1,
apply ennreal.sub_eq_of_add_eq
(ne_top_of_le_ne_top utop (measure_mono (inter_subset_right _ _))),
rw [inter_comm _ u, inter_comm _ u],
exact measure_inter_add_diff u vmeas },
have L : tendsto (λ r, μ (sᶜ ∩ closed_ball x r) / μ (closed_ball x r)) (𝓝[>] 0) (𝓝 0),
{ have A : tendsto (λ r, μ (closed_ball x r) / μ (closed_ball x r)) (𝓝[>] 0) (𝓝 1),
{ apply tendsto_const_nhds.congr' _,
filter_upwards [self_mem_nhds_within],
assume r hr,
rw [div_eq_mul_inv, ennreal.mul_inv_cancel],
{ exact (measure_closed_ball_pos μ _ hr).ne' },
{ exact measure_closed_ball_lt_top.ne } },
have B := ennreal.tendsto.sub A h (or.inl ennreal.one_ne_top),
simp only [tsub_self] at B,
apply B.congr' _,
filter_upwards [self_mem_nhds_within],
rintros r (rpos : 0 < r),
convert I (closed_ball x r) sᶜ (measure_closed_ball_pos μ _ rpos).ne'
(measure_closed_ball_lt_top).ne hs.compl,
rw compl_compl },
have L' : tendsto (λ (r : ℝ), μ (sᶜ ∩ ({x} + r • t)) / μ ({x} + r • t)) (𝓝[>] 0) (𝓝 0) :=
tendsto_add_haar_inter_smul_zero_of_density_zero μ sᶜ x L t ht h''t,
have L'' : tendsto (λ (r : ℝ), μ ({x} + r • t) / μ ({x} + r • t)) (𝓝[>] 0) (𝓝 1),
{ apply tendsto_const_nhds.congr' _,
filter_upwards [self_mem_nhds_within],
rintros r (rpos : 0 < r),
rw [add_haar_singleton_add_smul_div_singleton_add_smul μ rpos.ne', ennreal.div_self h't h''t] },
have := ennreal.tendsto.sub L'' L' (or.inl ennreal.one_ne_top),
simp only [tsub_zero] at this,
apply this.congr' _,
filter_upwards [self_mem_nhds_within],
rintros r (rpos : 0 < r),
refine I ({x} + r • t) s _ _ hs,
{ simp only [h't, abs_of_nonneg rpos.le, pow_pos rpos, add_haar_smul, image_add_left,
ennreal.of_real_eq_zero, not_le, or_false, ne.def, measure_preimage_add, abs_pow,
singleton_add, mul_eq_zero] },
{ simp only [h''t, ennreal.of_real_ne_top, add_haar_smul, image_add_left, with_top.mul_eq_top_iff,
ne.def, not_false_iff, measure_preimage_add, singleton_add, and_false, false_and, or_self] }
end
/-- Consider a point `x` at which a set `s` has density one, with respect to closed balls (i.e.,
a Lebesgue density point of `s`). Then `s` has also density one at `x` with respect to any
measurable set `t`: the proportion of points in `s` belonging to a rescaled copy `{x} + r • t`
of `t` tends to one as `r` tends to zero. -/
lemma tendsto_add_haar_inter_smul_one_of_density_one
(s : set E) (x : E)
(h : tendsto (λ r, μ (s ∩ closed_ball x r) / μ (closed_ball x r)) (𝓝[>] 0) (𝓝 1))
(t : set E) (ht : measurable_set t) (h't : μ t ≠ 0) (h''t : μ t ≠ ∞) :
tendsto (λ (r : ℝ), μ (s ∩ ({x} + r • t)) / μ ({x} + r • t)) (𝓝[>] 0) (𝓝 1) :=
begin
have : tendsto (λ (r : ℝ), μ (to_measurable μ s ∩ ({x} + r • t)) / μ ({x} + r • t))
(𝓝[>] 0) (𝓝 1),
{ apply tendsto_add_haar_inter_smul_one_of_density_one_aux μ _
(measurable_set_to_measurable _ _) _ _ t ht h't h''t,
apply tendsto_of_tendsto_of_tendsto_of_le_of_le' h tendsto_const_nhds,
{ apply eventually_of_forall (λ r, _),
apply ennreal.mul_le_mul _ le_rfl,
exact measure_mono (inter_subset_inter_left _ (subset_to_measurable _ _)) },
{ filter_upwards [self_mem_nhds_within],
rintros r (rpos : 0 < r),
apply ennreal.div_le_of_le_mul,
rw one_mul,
exact measure_mono (inter_subset_right _ _) } },
apply this.congr (λ r, _),
congr' 1,
apply measure_to_measurable_inter_of_sigma_finite,
simp only [image_add_left, singleton_add],
apply (continuous_add_left (-x)).measurable (ht.const_smul₀ r)
end
/-- Consider a point `x` at which a set `s` has density one, with respect to closed balls (i.e.,
a Lebesgue density point of `s`). Then `s` intersects the rescaled copies `{x} + r • t` of a given
set `t` with positive measure, for any small enough `r`. -/
lemma eventually_nonempty_inter_smul_of_density_one (s : set E) (x : E)
(h : tendsto (λ r, μ (s ∩ closed_ball x r) / μ (closed_ball x r)) (𝓝[>] 0) (𝓝 1))
(t : set E) (ht : measurable_set t) (h't : μ t ≠ 0) :
∀ᶠ r in 𝓝[>] (0 : ℝ), (s ∩ ({x} + r • t)).nonempty :=
begin
obtain ⟨t', t'_meas, t't, t'pos, t'top⟩ :
∃ t', measurable_set t' ∧ t' ⊆ t ∧ 0 < μ t' ∧ μ t' < ⊤ :=
exists_subset_measure_lt_top ht h't.bot_lt,
filter_upwards [(tendsto_order.1
(tendsto_add_haar_inter_smul_one_of_density_one μ s x h t'
t'_meas t'pos.ne' t'top.ne)).1 0 ennreal.zero_lt_one],
assume r hr,
have : μ (s ∩ ({x} + r • t')) ≠ 0 :=
λ h', by simpa only [ennreal.not_lt_zero, ennreal.zero_div, h'] using hr,
have : (s ∩ ({x} + r • t')).nonempty := nonempty_of_measure_ne_zero this,
apply this.mono (inter_subset_inter subset.rfl _),
exact add_subset_add subset.rfl (smul_set_mono t't),
end
end measure
end measure_theory
|
3031863a178ab25579c437c4a4327b8ab8d18fcf | 947b78d97130d56365ae2ec264df196ce769371a | /tests/lean/typeOf.lean | 700f4a8f5d6e87d24d562c5cae6b61bbcf53fa26 | [
"Apache-2.0"
] | permissive | shyamalschandra/lean4 | 27044812be8698f0c79147615b1d5090b9f4b037 | 6e7a883b21eaf62831e8111b251dc9b18f40e604 | refs/heads/master | 1,671,417,126,371 | 1,601,859,995,000 | 1,601,860,020,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 526 | lean | new_frontend
def f1 (x : Nat) (b : Bool) : typeOf! x :=
let r : typeOf! (x+1) := x+1;
r + 1
theorem ex1 : f1 1 true = 3 :=
rfl
def f2 (x : Nat) (b : Bool) : typeOf! x :=
let r : typeOf! b := x+1; -- error
r + 1
def f3 (x : Nat) (b : Bool) : typeOf! b :=
let r (x!1 : typeOf! x) : typeOf! b := x > 1;
r x
def f4 (x : Nat) : Nat :=
let y : Nat := x
let y := ensureTypeOf! y "invalid reassignment" y == 1 -- error
y + 1
def f5 (x : Nat) : Nat :=
let y : Nat := x
let y := ensureTypeOf! y "invalid reassignment" (y+1)
y + 1
|
a5eec26cb6f314d1c35a8a8096bdb651dc58b32a | 4727251e0cd73359b15b664c3170e5d754078599 | /src/category_theory/functor/hom.lean | 05b6f7a0e70470caacba10355ecc1470367644a6 | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 914 | lean | /-
Copyright (c) 2018 Reid Barton. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Reid Barton, Scott Morrison
-/
import category_theory.products.basic
import category_theory.types
/-!
The hom functor, sending `(X, Y)` to the type `X ⟶ Y`.
-/
universes v u
open opposite
open category_theory
namespace category_theory.functor
variables (C : Type u) [category.{v} C]
/-- `functor.hom` is the hom-pairing, sending `(X, Y)` to `X ⟶ Y`, contravariant in `X` and
covariant in `Y`. -/
definition hom : Cᵒᵖ × C ⥤ Type v :=
{ obj := λ p, unop p.1 ⟶ p.2,
map := λ X Y f, λ h, f.1.unop ≫ h ≫ f.2 }
@[simp] lemma hom_obj (X : Cᵒᵖ × C) : (hom C).obj X = (unop X.1 ⟶ X.2) := rfl
@[simp] lemma hom_pairing_map {X Y : Cᵒᵖ × C} (f : X ⟶ Y) :
(hom C).map f = λ h, f.1.unop ≫ h ≫ f.2 := rfl
end category_theory.functor
|
acdd899315a9fa7fed8b8789d1f985aab2ee41a2 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/data/real/sqrt_auto.lean | 365621f02e29bbebb6aa99dbc2083ae0b4839ceb | [] | no_license | AurelienSaue/Mathlib4_auto | f538cfd0980f65a6361eadea39e6fc639e9dae14 | 590df64109b08190abe22358fabc3eae000943f2 | refs/heads/master | 1,683,906,849,776 | 1,622,564,669,000 | 1,622,564,669,000 | 371,723,747 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 9,810 | lean | /-
Copyright (c) 2020 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro, Floris van Doorn, Yury Kudryashov
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.topology.instances.nnreal
import Mathlib.PostPort
universes u_1
namespace Mathlib
/-!
# Square root of a real number
In this file we define
* `nnreal.sqrt` to be the square root of a nonnegative real number.
* `real.sqrt` to be the square root of a real number, defined to be zero on negative numbers.
Then we prove some basic properties of these functions.
## Implementation notes
We define `nnreal.sqrt` as the noncomputable inverse to the function `x ↦ x * x`. We use general
theory of inverses of strictly monotone functions to prove that `nnreal.sqrt x` exists. As a side
effect, `nnreal.sqrt` is a bundled `order_iso`, so for `nnreal` numbers we get continuity as well as
theorems like `sqrt x ≤ y ↔ x * x ≤ y` for free.
Then we define `real.sqrt x` to be `nnreal.sqrt (nnreal.of_real x)`. We also define a Cauchy
sequence `real.sqrt_aux (f : cau_seq ℚ abs)` which converges to `sqrt (mk f)` but do not prove (yet)
that this sequence actually converges to `sqrt (mk f)`.
## Tags
square root
-/
namespace nnreal
/-- Square root of a nonnegative real number. -/
def sqrt : nnreal ≃o nnreal :=
order_iso.symm (strict_mono.order_iso_of_surjective (fun (x : nnreal) => x * x) sorry sorry)
theorem sqrt_eq_iff_sqr_eq {x : nnreal} {y : nnreal} : coe_fn sqrt x = y ↔ y * y = x :=
iff.trans (equiv.apply_eq_iff_eq_symm_apply (rel_iso.to_equiv sqrt)) eq_comm
theorem sqrt_le_iff {x : nnreal} {y : nnreal} : coe_fn sqrt x ≤ y ↔ x ≤ y * y :=
order_iso.to_galois_connection sqrt x y
theorem le_sqrt_iff {x : nnreal} {y : nnreal} : x ≤ coe_fn sqrt y ↔ x * x ≤ y :=
iff.symm (order_iso.to_galois_connection (order_iso.symm sqrt) x y)
@[simp] theorem sqrt_eq_zero {x : nnreal} : coe_fn sqrt x = 0 ↔ x = 0 :=
iff.trans sqrt_eq_iff_sqr_eq
(eq.mpr (id (Eq._oldrec (Eq.refl (0 * 0 = x ↔ x = 0)) (propext eq_comm)))
(eq.mpr (id (Eq._oldrec (Eq.refl (x = 0 * 0 ↔ x = 0)) (zero_mul 0))) (iff.refl (x = 0))))
@[simp] theorem sqrt_zero : coe_fn sqrt 0 = 0 := iff.mpr sqrt_eq_zero rfl
@[simp] theorem sqrt_one : coe_fn sqrt 1 = 1 := iff.mpr sqrt_eq_iff_sqr_eq (mul_one 1)
@[simp] theorem mul_sqrt_self (x : nnreal) : coe_fn sqrt x * coe_fn sqrt x = x :=
order_iso.symm_apply_apply sqrt x
@[simp] theorem sqrt_mul_self (x : nnreal) : coe_fn sqrt (x * x) = x :=
order_iso.apply_symm_apply sqrt x
theorem sqrt_mul (x : nnreal) (y : nnreal) : coe_fn sqrt (x * y) = coe_fn sqrt x * coe_fn sqrt y :=
sorry
/-- `nnreal.sqrt` as a `monoid_with_zero_hom`. -/
def sqrt_hom : monoid_with_zero_hom nnreal nnreal :=
monoid_with_zero_hom.mk (⇑sqrt) sqrt_zero sqrt_one sqrt_mul
theorem sqrt_inv (x : nnreal) : coe_fn sqrt (x⁻¹) = (coe_fn sqrt x⁻¹) :=
monoid_with_zero_hom.map_inv' sqrt_hom x
theorem sqrt_div (x : nnreal) (y : nnreal) : coe_fn sqrt (x / y) = coe_fn sqrt x / coe_fn sqrt y :=
monoid_with_zero_hom.map_div sqrt_hom x y
theorem continuous_sqrt : continuous ⇑sqrt := order_iso.continuous sqrt
end nnreal
namespace real
/-- An auxiliary sequence of rational numbers that converges to `real.sqrt (mk f)`.
Currently this sequence is not used in `mathlib`. -/
def sqrt_aux (f : cau_seq ℚ abs) : ℕ → ℚ := sorry
theorem sqrt_aux_nonneg (f : cau_seq ℚ abs) (i : ℕ) : 0 ≤ sqrt_aux f i := sorry
/- TODO(Mario): finish the proof
theorem sqrt_aux_converges (f : cau_seq ℚ abs) : ∃ h x, 0 ≤ x ∧ x * x = max 0 (mk f) ∧
mk ⟨sqrt_aux f, h⟩ = x :=
begin
rcases sqrt_exists (le_max_left 0 (mk f)) with ⟨x, x0, hx⟩,
suffices : ∃ h, mk ⟨sqrt_aux f, h⟩ = x,
{ exact this.imp (λ h e, ⟨x, x0, hx, e⟩) },
apply of_near,
suffices : ∃ δ > 0, ∀ i, abs (↑(sqrt_aux f i) - x) < δ / 2 ^ i,
{ rcases this with ⟨δ, δ0, hδ⟩,
intros,
}
end -/
/-- The square root of a real number. This returns 0 for negative inputs. -/
def sqrt (x : ℝ) : ℝ := ↑(coe_fn nnreal.sqrt (nnreal.of_real x))
/-quotient.lift_on x
(λ f, mk ⟨sqrt_aux f, (sqrt_aux_converges f).fst⟩)
(λ f g e, begin
rcases sqrt_aux_converges f with ⟨hf, x, x0, xf, xs⟩,
rcases sqrt_aux_converges g with ⟨hg, y, y0, yg, ys⟩,
refine xs.trans (eq.trans _ ys.symm),
rw [← @mul_self_inj_of_nonneg ℝ _ x y x0 y0, xf, yg],
congr' 1, exact quotient.sound e
end)-/
theorem continuous_sqrt : continuous sqrt :=
continuous.comp nnreal.continuous_coe
(continuous.comp (order_iso.continuous nnreal.sqrt) nnreal.continuous_of_real)
theorem sqrt_eq_zero_of_nonpos {x : ℝ} (h : x ≤ 0) : sqrt x = 0 := sorry
theorem sqrt_nonneg (x : ℝ) : 0 ≤ sqrt x :=
nnreal.coe_nonneg (coe_fn nnreal.sqrt (nnreal.of_real x))
@[simp] theorem mul_self_sqrt {x : ℝ} (h : 0 ≤ x) : sqrt x * sqrt x = x := sorry
@[simp] theorem sqrt_mul_self {x : ℝ} (h : 0 ≤ x) : sqrt (x * x) = x :=
iff.mp (mul_self_inj_of_nonneg (sqrt_nonneg (x * x)) h) (mul_self_sqrt (mul_self_nonneg x))
theorem sqrt_eq_iff_mul_self_eq {x : ℝ} {y : ℝ} (hx : 0 ≤ x) (hy : 0 ≤ y) :
sqrt x = y ↔ y * y = x :=
sorry
@[simp] theorem sqr_sqrt {x : ℝ} (h : 0 ≤ x) : sqrt x ^ bit0 1 = x :=
eq.mpr (id (Eq._oldrec (Eq.refl (sqrt x ^ bit0 1 = x)) (pow_two (sqrt x))))
(eq.mpr (id (Eq._oldrec (Eq.refl (sqrt x * sqrt x = x)) (mul_self_sqrt h))) (Eq.refl x))
@[simp] theorem sqrt_sqr {x : ℝ} (h : 0 ≤ x) : sqrt (x ^ bit0 1) = x :=
eq.mpr (id (Eq._oldrec (Eq.refl (sqrt (x ^ bit0 1) = x)) (pow_two x)))
(eq.mpr (id (Eq._oldrec (Eq.refl (sqrt (x * x) = x)) (sqrt_mul_self h))) (Eq.refl x))
theorem sqrt_eq_iff_sqr_eq {x : ℝ} {y : ℝ} (hx : 0 ≤ x) (hy : 0 ≤ y) :
sqrt x = y ↔ y ^ bit0 1 = x :=
eq.mpr (id (Eq._oldrec (Eq.refl (sqrt x = y ↔ y ^ bit0 1 = x)) (pow_two y)))
(eq.mpr
(id (Eq._oldrec (Eq.refl (sqrt x = y ↔ y * y = x)) (propext (sqrt_eq_iff_mul_self_eq hx hy))))
(iff.refl (y * y = x)))
theorem sqrt_mul_self_eq_abs (x : ℝ) : sqrt (x * x) = abs x :=
eq.mpr (id (Eq._oldrec (Eq.refl (sqrt (x * x) = abs x)) (Eq.symm (abs_mul_abs_self x))))
(eq.mpr
(id (Eq._oldrec (Eq.refl (sqrt (abs x * abs x) = abs x)) (sqrt_mul_self (abs_nonneg x))))
(Eq.refl (abs x)))
theorem sqrt_sqr_eq_abs (x : ℝ) : sqrt (x ^ bit0 1) = abs x :=
eq.mpr (id (Eq._oldrec (Eq.refl (sqrt (x ^ bit0 1) = abs x)) (pow_two x)))
(eq.mpr (id (Eq._oldrec (Eq.refl (sqrt (x * x) = abs x)) (sqrt_mul_self_eq_abs x)))
(Eq.refl (abs x)))
@[simp] theorem sqrt_zero : sqrt 0 = 0 := sorry
@[simp] theorem sqrt_one : sqrt 1 = 1 := sorry
@[simp] theorem sqrt_le {x : ℝ} {y : ℝ} (hy : 0 ≤ y) : sqrt x ≤ sqrt y ↔ x ≤ y := sorry
@[simp] theorem sqrt_lt {x : ℝ} {y : ℝ} (hx : 0 ≤ x) : sqrt x < sqrt y ↔ x < y :=
lt_iff_lt_of_le_iff_le (sqrt_le hx)
theorem sqrt_le_sqrt {x : ℝ} {y : ℝ} (h : x ≤ y) : sqrt x ≤ sqrt y := sorry
theorem sqrt_le_left {x : ℝ} {y : ℝ} (hy : 0 ≤ y) : sqrt x ≤ y ↔ x ≤ y ^ bit0 1 := sorry
theorem sqrt_le_iff {x : ℝ} {y : ℝ} : sqrt x ≤ y ↔ 0 ≤ y ∧ x ≤ y ^ bit0 1 := sorry
/- note: if you want to conclude `x ≤ sqrt y`, then use `le_sqrt_of_sqr_le`.
if you have `x > 0`, consider using `le_sqrt'` -/
theorem le_sqrt {x : ℝ} {y : ℝ} (hx : 0 ≤ x) (hy : 0 ≤ y) : x ≤ sqrt y ↔ x ^ bit0 1 ≤ y := sorry
theorem le_sqrt' {x : ℝ} {y : ℝ} (hx : 0 < x) : x ≤ sqrt y ↔ x ^ bit0 1 ≤ y := sorry
theorem le_sqrt_of_sqr_le {x : ℝ} {y : ℝ} (h : x ^ bit0 1 ≤ y) : x ≤ sqrt y :=
or.dcases_on (lt_or_ge 0 x)
(fun (hx : 0 < x) => eq.mpr (id (Eq._oldrec (Eq.refl (x ≤ sqrt y)) (propext (le_sqrt' hx)))) h)
fun (hx : 0 ≥ x) => le_trans hx (sqrt_nonneg y)
@[simp] theorem sqrt_inj {x : ℝ} {y : ℝ} (hx : 0 ≤ x) (hy : 0 ≤ y) : sqrt x = sqrt y ↔ x = y :=
sorry
@[simp] theorem sqrt_eq_zero {x : ℝ} (h : 0 ≤ x) : sqrt x = 0 ↔ x = 0 := sorry
theorem sqrt_eq_zero' {x : ℝ} : sqrt x = 0 ↔ x ≤ 0 := sorry
@[simp] theorem sqrt_pos {x : ℝ} : 0 < sqrt x ↔ 0 < x := sorry
@[simp] theorem sqrt_mul {x : ℝ} (hx : 0 ≤ x) (y : ℝ) : sqrt (x * y) = sqrt x * sqrt y := sorry
@[simp] theorem sqrt_mul' (x : ℝ) {y : ℝ} (hy : 0 ≤ y) : sqrt (x * y) = sqrt x * sqrt y := sorry
@[simp] theorem sqrt_inv (x : ℝ) : sqrt (x⁻¹) = (sqrt x⁻¹) := sorry
@[simp] theorem sqrt_div {x : ℝ} (hx : 0 ≤ x) (y : ℝ) : sqrt (x / y) = sqrt x / sqrt y := sorry
end real
theorem filter.tendsto.sqrt {α : Type u_1} {f : α → ℝ} {l : filter α} {x : ℝ}
(h : filter.tendsto f l (nhds x)) :
filter.tendsto (fun (x : α) => real.sqrt (f x)) l (nhds (real.sqrt x)) :=
filter.tendsto.comp (continuous.tendsto real.continuous_sqrt x) h
theorem continuous_within_at.sqrt {α : Type u_1} [topological_space α] {f : α → ℝ} {s : set α}
{x : α} (h : continuous_within_at f s x) :
continuous_within_at (fun (x : α) => real.sqrt (f x)) s x :=
filter.tendsto.sqrt h
theorem continuous_at.sqrt {α : Type u_1} [topological_space α] {f : α → ℝ} {x : α}
(h : continuous_at f x) : continuous_at (fun (x : α) => real.sqrt (f x)) x :=
filter.tendsto.sqrt h
theorem continuous_on.sqrt {α : Type u_1} [topological_space α] {f : α → ℝ} {s : set α}
(h : continuous_on f s) : continuous_on (fun (x : α) => real.sqrt (f x)) s :=
fun (x : α) (hx : x ∈ s) => continuous_within_at.sqrt (h x hx)
theorem continuous.sqrt {α : Type u_1} [topological_space α] {f : α → ℝ} (h : continuous f) :
continuous fun (x : α) => real.sqrt (f x) :=
continuous.comp real.continuous_sqrt h
end Mathlib |
3c8c8845d07754fd39ba72a88df8a100cd414fbb | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/control/traversable/instances_auto.lean | 9f100b983442b5c1067bd11a77d37f32af5ca68f | [] | no_license | AurelienSaue/Mathlib4_auto | f538cfd0980f65a6361eadea39e6fc639e9dae14 | 590df64109b08190abe22358fabc3eae000943f2 | refs/heads/master | 1,683,906,849,776 | 1,622,564,669,000 | 1,622,564,669,000 | 371,723,747 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 6,026 | lean | /-
Copyright (c) 2018 Simon Hudon. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Simon Hudon
Instances of `traversable` for types from the core library
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.data.list.forall2
import Mathlib.data.set.lattice
import Mathlib.control.traversable.lemmas
import Mathlib.PostPort
universes u_1 u
namespace Mathlib
theorem option.id_traverse {α : Type u_1} (x : Option α) : option.traverse id.mk x = x :=
option.cases_on x (Eq.refl (option.traverse id.mk none))
fun (x : α) => Eq.refl (option.traverse id.mk (some x))
theorem option.comp_traverse {F : Type u → Type u} {G : Type u → Type u} [Applicative F]
[Applicative G] [is_lawful_applicative F] [is_lawful_applicative G] {α : Type u_1} {β : Type u}
{γ : Type u} (f : β → F γ) (g : α → G β) (x : Option α) :
option.traverse (functor.comp.mk ∘ Functor.map f ∘ g) x =
functor.comp.mk (option.traverse f <$> option.traverse g x) :=
sorry
theorem option.traverse_eq_map_id {α : Type u_1} {β : Type u_1} (f : α → β) (x : Option α) :
traverse (id.mk ∘ f) x = id.mk (f <$> x) :=
option.cases_on x (Eq.refl (traverse (id.mk ∘ f) none))
fun (x : α) => Eq.refl (traverse (id.mk ∘ f) (some x))
theorem option.naturality {F : Type u → Type u} {G : Type u → Type u} [Applicative F]
[Applicative G] [is_lawful_applicative F] [is_lawful_applicative G]
(η : applicative_transformation F G) {α : Type u_1} {β : Type u} (f : α → F β) (x : Option α) :
coe_fn η (Option β) (option.traverse f x) = option.traverse (coe_fn η β ∘ f) x :=
sorry
protected instance option.is_lawful_traversable : is_lawful_traversable Option :=
is_lawful_traversable.mk option.id_traverse option.comp_traverse option.traverse_eq_map_id
option.naturality
namespace list
protected theorem id_traverse {α : Type u_1} (xs : List α) : list.traverse id.mk xs = xs := sorry
protected theorem comp_traverse {F : Type u → Type u} {G : Type u → Type u} [Applicative F]
[Applicative G] [is_lawful_applicative F] [is_lawful_applicative G] {α : Type u_1} {β : Type u}
{γ : Type u} (f : β → F γ) (g : α → G β) (x : List α) :
list.traverse (functor.comp.mk ∘ Functor.map f ∘ g) x =
functor.comp.mk (list.traverse f <$> list.traverse g x) :=
sorry
protected theorem traverse_eq_map_id {α : Type u_1} {β : Type u_1} (f : α → β) (x : List α) :
list.traverse (id.mk ∘ f) x = id.mk (f <$> x) :=
sorry
protected theorem naturality {F : Type u → Type u} {G : Type u → Type u} [Applicative F]
[Applicative G] [is_lawful_applicative F] [is_lawful_applicative G]
(η : applicative_transformation F G) {α : Type u_1} {β : Type u} (f : α → F β) (x : List α) :
coe_fn η (List β) (list.traverse f x) = list.traverse (coe_fn η β ∘ f) x :=
sorry
protected instance is_lawful_traversable : is_lawful_traversable List :=
is_lawful_traversable.mk list.id_traverse list.comp_traverse list.traverse_eq_map_id
list.naturality
@[simp] theorem traverse_nil {F : Type u → Type u} [Applicative F] {α' : Type u} {β' : Type u}
(f : α' → F β') : traverse f [] = pure [] :=
rfl
@[simp] theorem traverse_cons {F : Type u → Type u} [Applicative F] {α' : Type u} {β' : Type u}
(f : α' → F β') (a : α') (l : List α') :
traverse f (a :: l) = (fun (_x : β') (_y : List β') => _x :: _y) <$> f a <*> traverse f l :=
rfl
@[simp] theorem traverse_append {F : Type u → Type u} [Applicative F] {α' : Type u} {β' : Type u}
(f : α' → F β') [is_lawful_applicative F] (as : List α') (bs : List α') :
traverse f (as ++ bs) = append <$> traverse f as <*> traverse f bs :=
sorry
theorem mem_traverse {α' : Type u} {β' : Type u} {f : α' → set β'} (l : List α') (n : List β') :
n ∈ traverse f l ↔ forall₂ (fun (b : β') (a : α') => b ∈ f a) n l :=
sorry
end list
namespace sum
protected theorem traverse_map {σ : Type u} {G : Type u → Type u} [Applicative G] {α : Type u}
{β : Type u} {γ : Type u} (g : α → β) (f : β → G γ) (x : σ ⊕ α) :
sum.traverse f (g <$> x) = sum.traverse (f ∘ g) x :=
sorry
protected theorem id_traverse {σ : Type u_1} {α : Type u_1} (x : σ ⊕ α) :
sum.traverse id.mk x = x :=
sum.cases_on x (fun (x : σ) => Eq.refl (sum.traverse id.mk (inl x)))
fun (x : α) => Eq.refl (sum.traverse id.mk (inr x))
protected theorem comp_traverse {σ : Type u} {F : Type u → Type u} {G : Type u → Type u}
[Applicative F] [Applicative G] [is_lawful_applicative F] [is_lawful_applicative G]
{α : Type u_1} {β : Type u} {γ : Type u} (f : β → F γ) (g : α → G β) (x : σ ⊕ α) :
sum.traverse (functor.comp.mk ∘ Functor.map f ∘ g) x =
functor.comp.mk (sum.traverse f <$> sum.traverse g x) :=
sorry
protected theorem traverse_eq_map_id {σ : Type u} {α : Type u} {β : Type u} (f : α → β)
(x : σ ⊕ α) : sum.traverse (id.mk ∘ f) x = id.mk (f <$> x) :=
sorry
protected theorem map_traverse {σ : Type u} {G : Type u → Type u} [Applicative G]
[is_lawful_applicative G] {α : Type u_1} {β : Type u} {γ : Type u} (g : α → G β) (f : β → γ)
(x : σ ⊕ α) : Functor.map f <$> sum.traverse g x = sum.traverse (Functor.map f ∘ g) x :=
sorry
protected theorem naturality {σ : Type u} {F : Type u → Type u} {G : Type u → Type u}
[Applicative F] [Applicative G] [is_lawful_applicative F] [is_lawful_applicative G]
(η : applicative_transformation F G) {α : Type u_1} {β : Type u} (f : α → F β) (x : σ ⊕ α) :
coe_fn η (σ ⊕ β) (sum.traverse f x) = sum.traverse (coe_fn η β ∘ f) x :=
sorry
protected instance is_lawful_traversable {σ : Type u} : is_lawful_traversable (sum σ) :=
is_lawful_traversable.mk sum.id_traverse sum.comp_traverse sum.traverse_eq_map_id sum.naturality
end Mathlib |
3091c01247dba7954c43655c98bf3be8dc7da332 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/analysis/analytic/inverse.lean | b62140919527552491a8c9d9c4de52ca75641b0e | [
"Apache-2.0"
] | permissive | jcommelin/mathlib | d8456447c36c176e14d96d9e76f39841f69d2d9b | ee8279351a2e434c2852345c51b728d22af5a156 | refs/heads/master | 1,664,782,136,488 | 1,663,638,983,000 | 1,663,638,983,000 | 132,563,656 | 0 | 0 | Apache-2.0 | 1,663,599,929,000 | 1,525,760,539,000 | Lean | UTF-8 | Lean | false | false | 27,270 | lean | /-
Copyright (c) 2021 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Sébastien Gouëzel
-/
import analysis.analytic.composition
import tactic.congrm
/-!
# Inverse of analytic functions
We construct the left and right inverse of a formal multilinear series with invertible linear term,
we prove that they coincide and study their properties (notably convergence).
## Main statements
* `p.left_inv i`: the formal left inverse of the formal multilinear series `p`,
for `i : E ≃L[𝕜] F` which coincides with `p₁`.
* `p.right_inv i`: the formal right inverse of the formal multilinear series `p`,
for `i : E ≃L[𝕜] F` which coincides with `p₁`.
* `p.left_inv_comp` says that `p.left_inv i` is indeed a left inverse to `p` when `p₁ = i`.
* `p.right_inv_comp` says that `p.right_inv i` is indeed a right inverse to `p` when `p₁ = i`.
* `p.left_inv_eq_right_inv`: the two inverses coincide.
* `p.radius_right_inv_pos_of_radius_pos`: if a power series has a positive radius of convergence,
then so does its inverse.
-/
open_locale big_operators classical topological_space
open finset filter
namespace formal_multilinear_series
variables {𝕜 : Type*} [nontrivially_normed_field 𝕜]
{E : Type*} [normed_add_comm_group E] [normed_space 𝕜 E]
{F : Type*} [normed_add_comm_group F] [normed_space 𝕜 F]
/-! ### The left inverse of a formal multilinear series -/
/-- The left inverse of a formal multilinear series, where the `n`-th term is defined inductively
in terms of the previous ones to make sure that `(left_inv p i) ∘ p = id`. For this, the linear term
`p₁` in `p` should be invertible. In the definition, `i` is a linear isomorphism that should
coincide with `p₁`, so that one can use its inverse in the construction. The definition does not
use that `i = p₁`, but proofs that the definition is well-behaved do.
The `n`-th term in `q ∘ p` is `∑ qₖ (p_{j₁}, ..., p_{jₖ})` over `j₁ + ... + jₖ = n`. In this
expression, `qₙ` appears only once, in `qₙ (p₁, ..., p₁)`. We adjust the definition so that this
term compensates the rest of the sum, using `i⁻¹` as an inverse to `p₁`.
These formulas only make sense when the constant term `p₀` vanishes. The definition we give is
general, but it ignores the value of `p₀`.
-/
noncomputable def left_inv (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) :
formal_multilinear_series 𝕜 F E
| 0 := 0
| 1 := (continuous_multilinear_curry_fin1 𝕜 F E).symm i.symm
| (n+2) := - ∑ c : {c : composition (n+2) // c.length < n + 2},
have (c : composition (n+2)).length < n+2 := c.2,
(left_inv (c : composition (n+2)).length).comp_along_composition
(p.comp_continuous_linear_map i.symm) c
@[simp] lemma left_inv_coeff_zero (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) :
p.left_inv i 0 = 0 := by rw left_inv
@[simp] lemma left_inv_coeff_one (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) :
p.left_inv i 1 = (continuous_multilinear_curry_fin1 𝕜 F E).symm i.symm := by rw left_inv
/-- The left inverse does not depend on the zeroth coefficient of a formal multilinear
series. -/
lemma left_inv_remove_zero (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) :
p.remove_zero.left_inv i = p.left_inv i :=
begin
ext1 n,
induction n using nat.strong_rec' with n IH,
cases n, { simp }, -- if one replaces `simp` with `refl`, the proof times out in the kernel.
cases n, { simp }, -- TODO: why?
simp only [left_inv, neg_inj],
refine finset.sum_congr rfl (λ c cuniv, _),
rcases c with ⟨c, hc⟩,
ext v,
dsimp,
simp [IH _ hc],
end
/-- The left inverse to a formal multilinear series is indeed a left inverse, provided its linear
term is invertible. -/
lemma left_inv_comp (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F)
(h : p 1 = (continuous_multilinear_curry_fin1 𝕜 E F).symm i) :
(left_inv p i).comp p = id 𝕜 E :=
begin
ext n v,
cases n,
{ simp only [left_inv, continuous_multilinear_map.zero_apply, id_apply_ne_one, ne.def,
not_false_iff, zero_ne_one, comp_coeff_zero']},
cases n,
{ simp only [left_inv, comp_coeff_one, h, id_apply_one, continuous_linear_equiv.coe_apply,
continuous_linear_equiv.symm_apply_apply, continuous_multilinear_curry_fin1_symm_apply] },
have A : (finset.univ : finset (composition (n+2)))
= {c | composition.length c < n + 2}.to_finset ∪ {composition.ones (n+2)},
{ refine subset.antisymm (λ c hc, _) (subset_univ _),
by_cases h : c.length < n + 2,
{ simp [h] },
{ simp [composition.eq_ones_iff_le_length.2 (not_lt.1 h)] } },
have B : disjoint ({c | composition.length c < n + 2} : set (composition (n + 2))).to_finset
{composition.ones (n+2)}, by simp,
have C : (p.left_inv i (composition.ones (n + 2)).length)
(λ (j : fin (composition.ones n.succ.succ).length), p 1 (λ k,
v ((fin.cast_le (composition.length_le _)) j)))
= p.left_inv i (n+2) (λ (j : fin (n+2)), p 1 (λ k, v j)),
{ apply formal_multilinear_series.congr _ (composition.ones_length _) (λ j hj1 hj2, _),
exact formal_multilinear_series.congr _ rfl (λ k hk1 hk2, by congr) },
have D : p.left_inv i (n+2) (λ (j : fin (n+2)), p 1 (λ k, v j)) =
- ∑ (c : composition (n + 2)) in {c : composition (n + 2) | c.length < n + 2}.to_finset,
(p.left_inv i c.length) (p.apply_composition c v),
{ simp only [left_inv, continuous_multilinear_map.neg_apply, neg_inj,
continuous_multilinear_map.sum_apply],
convert (sum_to_finset_eq_subtype (λ (c : composition (n+2)), c.length < n+2)
(λ (c : composition (n+2)), (continuous_multilinear_map.comp_along_composition
(p.comp_continuous_linear_map ↑(i.symm)) c (p.left_inv i c.length))
(λ (j : fin (n + 2)), p 1 (λ (k : fin 1), v j)))).symm.trans _,
simp only [comp_continuous_linear_map_apply_composition,
continuous_multilinear_map.comp_along_composition_apply],
congr,
ext c,
congr,
ext k,
simp [h] },
simp [formal_multilinear_series.comp, show n + 2 ≠ 1, by dec_trivial, A, finset.sum_union B,
apply_composition_ones, C, D],
end
/-! ### The right inverse of a formal multilinear series -/
/-- The right inverse of a formal multilinear series, where the `n`-th term is defined inductively
in terms of the previous ones to make sure that `p ∘ (right_inv p i) = id`. For this, the linear
term `p₁` in `p` should be invertible. In the definition, `i` is a linear isomorphism that should
coincide with `p₁`, so that one can use its inverse in the construction. The definition does not
use that `i = p₁`, but proofs that the definition is well-behaved do.
The `n`-th term in `p ∘ q` is `∑ pₖ (q_{j₁}, ..., q_{jₖ})` over `j₁ + ... + jₖ = n`. In this
expression, `qₙ` appears only once, in `p₁ (qₙ)`. We adjust the definition of `qₙ` so that this
term compensates the rest of the sum, using `i⁻¹` as an inverse to `p₁`.
These formulas only make sense when the constant term `p₀` vanishes. The definition we give is
general, but it ignores the value of `p₀`.
-/
noncomputable def right_inv (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) :
formal_multilinear_series 𝕜 F E
| 0 := 0
| 1 := (continuous_multilinear_curry_fin1 𝕜 F E).symm i.symm
| (n+2) :=
let q : formal_multilinear_series 𝕜 F E := λ k, if h : k < n + 2 then right_inv k else 0 in
- (i.symm : F →L[𝕜] E).comp_continuous_multilinear_map ((p.comp q) (n+2))
@[simp] lemma right_inv_coeff_zero (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) :
p.right_inv i 0 = 0 := by rw right_inv
@[simp] lemma right_inv_coeff_one (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) :
p.right_inv i 1 = (continuous_multilinear_curry_fin1 𝕜 F E).symm i.symm := by rw right_inv
/-- The right inverse does not depend on the zeroth coefficient of a formal multilinear
series. -/
lemma right_inv_remove_zero (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) :
p.remove_zero.right_inv i = p.right_inv i :=
begin
ext1 n,
induction n using nat.strong_rec' with n IH,
rcases n with _|_|n,
{ simp only [right_inv_coeff_zero] },
{ simp only [right_inv_coeff_one] },
simp only [right_inv, neg_inj],
rw remove_zero_comp_of_pos _ _ (add_pos_of_nonneg_of_pos (n.zero_le) zero_lt_two),
congrm i.symm.to_continuous_linear_map.comp_continuous_multilinear_map (p.comp (λ k, _) _),
by_cases hk : k < n+2; simp [hk, IH]
end
lemma comp_right_inv_aux1 {n : ℕ} (hn : 0 < n)
(p : formal_multilinear_series 𝕜 E F) (q : formal_multilinear_series 𝕜 F E) (v : fin n → F) :
p.comp q n v =
(∑ (c : composition n) in {c : composition n | 1 < c.length}.to_finset,
p c.length (q.apply_composition c v)) + p 1 (λ i, q n v) :=
begin
have A : (finset.univ : finset (composition n))
= {c | 1 < composition.length c}.to_finset ∪ {composition.single n hn},
{ refine subset.antisymm (λ c hc, _) (subset_univ _),
by_cases h : 1 < c.length,
{ simp [h] },
{ have : c.length = 1,
by { refine (eq_iff_le_not_lt.2 ⟨ _, h⟩).symm, exact c.length_pos_of_pos hn },
rw ← composition.eq_single_iff_length hn at this,
simp [this] } },
have B : disjoint ({c | 1 < composition.length c} : set (composition n)).to_finset
{composition.single n hn}, by simp,
have C : p (composition.single n hn).length
(q.apply_composition (composition.single n hn) v)
= p 1 (λ (i : fin 1), q n v),
{ apply p.congr (composition.single_length hn) (λ j hj1 hj2, _),
simp [apply_composition_single] },
simp [formal_multilinear_series.comp, A, finset.sum_union B, C],
end
lemma comp_right_inv_aux2
(p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) (n : ℕ) (v : fin (n + 2) → F) :
∑ (c : composition (n + 2)) in {c : composition (n + 2) | 1 < c.length}.to_finset,
p c.length (apply_composition (λ (k : ℕ), ite (k < n + 2) (p.right_inv i k) 0) c v) =
∑ (c : composition (n + 2)) in {c : composition (n + 2) | 1 < c.length}.to_finset,
p c.length ((p.right_inv i).apply_composition c v) :=
begin
have N : 0 < n + 2, by dec_trivial,
refine sum_congr rfl (λ c hc, p.congr rfl (λ j hj1 hj2, _)),
have : ∀ k, c.blocks_fun k < n + 2,
{ simp only [set.mem_to_finset, set.mem_set_of_eq] at hc,
simp [← composition.ne_single_iff N, composition.eq_single_iff_length, ne_of_gt hc] },
simp [apply_composition, this],
end
/-- The right inverse to a formal multilinear series is indeed a right inverse, provided its linear
term is invertible and its constant term vanishes. -/
lemma comp_right_inv (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F)
(h : p 1 = (continuous_multilinear_curry_fin1 𝕜 E F).symm i) (h0 : p 0 = 0) :
p.comp (right_inv p i) = id 𝕜 F :=
begin
ext n v,
cases n,
{ simp only [h0, continuous_multilinear_map.zero_apply, id_apply_ne_one, ne.def, not_false_iff,
zero_ne_one, comp_coeff_zero']},
cases n,
{ simp only [comp_coeff_one, h, right_inv, continuous_linear_equiv.apply_symm_apply, id_apply_one,
continuous_linear_equiv.coe_apply, continuous_multilinear_curry_fin1_symm_apply] },
have N : 0 < n+2, by dec_trivial,
simp [comp_right_inv_aux1 N, h, right_inv, lt_irrefl n, show n + 2 ≠ 1, by dec_trivial,
← sub_eq_add_neg, sub_eq_zero, comp_right_inv_aux2],
end
lemma right_inv_coeff (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F) (n : ℕ) (hn : 2 ≤ n) :
p.right_inv i n = - (i.symm : F →L[𝕜] E).comp_continuous_multilinear_map
(∑ c in ({c | 1 < composition.length c}.to_finset : finset (composition n)),
p.comp_along_composition (p.right_inv i) c) :=
begin
cases n, { exact false.elim (zero_lt_two.not_le hn) },
cases n, { exact false.elim (one_lt_two.not_le hn) },
simp only [right_inv, neg_inj],
congr' 1,
ext v,
have N : 0 < n + 2, by dec_trivial,
have : (p 1) (λ (i : fin 1), 0) = 0 := continuous_multilinear_map.map_zero _,
simp [comp_right_inv_aux1 N, lt_irrefl n, this, comp_right_inv_aux2]
end
/-! ### Coincidence of the left and the right inverse -/
private lemma left_inv_eq_right_inv_aux (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F)
(h : p 1 = (continuous_multilinear_curry_fin1 𝕜 E F).symm i) (h0 : p 0 = 0) :
left_inv p i = right_inv p i := calc
left_inv p i = (left_inv p i).comp (id 𝕜 F) : by simp
... = (left_inv p i).comp (p.comp (right_inv p i)) : by rw comp_right_inv p i h h0
... = ((left_inv p i).comp p).comp (right_inv p i) : by rw comp_assoc
... = (id 𝕜 E).comp (right_inv p i) : by rw left_inv_comp p i h
... = right_inv p i : by simp
/-- The left inverse and the right inverse of a formal multilinear series coincide. This is not at
all obvious from their definition, but it follows from uniqueness of inverses (which comes from the
fact that composition is associative on formal multilinear series). -/
theorem left_inv_eq_right_inv (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F)
(h : p 1 = (continuous_multilinear_curry_fin1 𝕜 E F).symm i) :
left_inv p i = right_inv p i := calc
left_inv p i = left_inv p.remove_zero i : by rw left_inv_remove_zero
... = right_inv p.remove_zero i : by { apply left_inv_eq_right_inv_aux; simp [h] }
... = right_inv p i : by rw right_inv_remove_zero
/-!
### Convergence of the inverse of a power series
Assume that `p` is a convergent multilinear series, and let `q` be its (left or right) inverse.
Using the left-inverse formula gives
$$
q_n = - (p_1)^{-n} \sum_{k=0}^{n-1} \sum_{i_1 + \dotsc + i_k = n} q_k (p_{i_1}, \dotsc, p_{i_k}).
$$
Assume for simplicity that we are in dimension `1` and `p₁ = 1`. In the formula for `qₙ`, the term
`q_{n-1}` appears with a multiplicity of `n-1` (choosing the index `i_j` for which `i_j = 2` while
all the other indices are equal to `1`), which indicates that `qₙ` might grow like `n!`. This is
bad for summability properties.
It turns out that the right-inverse formula is better behaved, and should instead be used for this
kind of estimate. It reads
$$
q_n = - (p_1)^{-1} \sum_{k=2}^n \sum_{i_1 + \dotsc + i_k = n} p_k (q_{i_1}, \dotsc, q_{i_k}).
$$
Here, `q_{n-1}` can only appear in the term with `k = 2`, and it only appears twice, so there is
hope this formula can lead to an at most geometric behavior.
Let `Qₙ = ∥qₙ∥`. Bounding `∥pₖ∥` with `C r^k` gives an inequality
$$
Q_n ≤ C' \sum_{k=2}^n r^k \sum_{i_1 + \dotsc + i_k = n} Q_{i_1} \dotsm Q_{i_k}.
$$
This formula is not enough to prove by naive induction on `n` a bound of the form `Qₙ ≤ D R^n`.
However, assuming that the inequality above were an equality, one could get a formula for the
generating series of the `Qₙ`:
$$
\begin{align}
Q(z) & := \sum Q_n z^n = Q_1 z + C' \sum_{2 \leq k \leq n} \sum_{i_1 + \dotsc + i_k = n}
(r z^{i_1} Q_{i_1}) \dotsm (r z^{i_k} Q_{i_k})
\\ & = Q_1 z + C' \sum_{k = 2}^\infty (\sum_{i_1 \geq 1} r z^{i_1} Q_{i_1})
\dotsm (\sum_{i_k \geq 1} r z^{i_k} Q_{i_k})
\\ & = Q_1 z + C' \sum_{k = 2}^\infty (r Q(z))^k
= Q_1 z + C' (r Q(z))^2 / (1 - r Q(z)).
\end{align}
$$
One can solve this formula explicitly. The solution is analytic in a neighborhood of `0` in `ℂ`,
hence its coefficients grow at most geometrically (by a contour integral argument), and therefore
the original `Qₙ`, which are bounded by these ones, are also at most geometric.
This classical argument is not really satisfactory, as it requires an a priori bound on a complex
analytic function. Another option would be to compute explicitly its terms (with binomial
coefficients) to obtain an explicit geometric bound, but this would be very painful.
Instead, we will use the above intuition, but in a slightly different form, with finite sums and an
induction. I learnt this trick in [pöschel2017siegelsternberg]. Let
$S_n = \sum_{k=1}^n Q_k a^k$ (where `a` is a positive real parameter to be chosen suitably small).
The above computation but with finite sums shows that
$$
S_n \leq Q_1 a + C' \sum_{k=2}^n (r S_{n-1})^k.
$$
In particular, $S_n \leq Q_1 a + C' (r S_{n-1})^2 / (1- r S_{n-1})$.
Assume that $S_{n-1} \leq K a$, where `K > Q₁` is fixed and `a` is small enough so that
`r K a ≤ 1/2` (to control the denominator). Then this equation gives a bound
$S_n \leq Q_1 a + 2 C' r^2 K^2 a^2$.
If `a` is small enough, this is bounded by `K a` as the second term is quadratic in `a`, and
therefore negligible.
By induction, we deduce `Sₙ ≤ K a` for all `n`, which gives in particular the fact that `aⁿ Qₙ`
remains bounded.
-/
/-- First technical lemma to control the growth of coefficients of the inverse. Bound the explicit
expression for `∑_{k<n+1} aᵏ Qₖ` in terms of a sum of powers of the same sum one step before,
in a general abstract setup. -/
lemma radius_right_inv_pos_of_radius_pos_aux1
(n : ℕ) (p : ℕ → ℝ) (hp : ∀ k, 0 ≤ p k) {r a : ℝ} (hr : 0 ≤ r) (ha : 0 ≤ a) :
∑ k in Ico 2 (n + 1), a ^ k *
(∑ c in ({c | 1 < composition.length c}.to_finset : finset (composition k)),
r ^ c.length * ∏ j, p (c.blocks_fun j))
≤ ∑ j in Ico 2 (n + 1), r ^ j * (∑ k in Ico 1 n, a ^ k * p k) ^ j :=
calc
∑ k in Ico 2 (n + 1), a ^ k *
(∑ c in ({c | 1 < composition.length c}.to_finset : finset (composition k)),
r ^ c.length * ∏ j, p (c.blocks_fun j))
= ∑ k in Ico 2 (n + 1),
(∑ c in ({c | 1 < composition.length c}.to_finset : finset (composition k)),
∏ j, r * (a ^ (c.blocks_fun j) * p (c.blocks_fun j))) :
begin
simp_rw [mul_sum],
apply sum_congr rfl (λ k hk, _),
apply sum_congr rfl (λ c hc, _),
rw [prod_mul_distrib, prod_mul_distrib, prod_pow_eq_pow_sum, composition.sum_blocks_fun,
prod_const, card_fin],
ring,
end
... ≤ ∑ d in comp_partial_sum_target 2 (n + 1) n,
∏ (j : fin d.2.length), r * (a ^ d.2.blocks_fun j * p (d.2.blocks_fun j)) :
begin
rw sum_sigma',
refine sum_le_sum_of_subset_of_nonneg _ (λ x hx1 hx2,
prod_nonneg (λ j hj, mul_nonneg hr (mul_nonneg (pow_nonneg ha _) (hp _)))),
rintros ⟨k, c⟩ hd,
simp only [set.mem_to_finset, mem_Ico, mem_sigma, set.mem_set_of_eq] at hd,
simp only [mem_comp_partial_sum_target_iff],
refine ⟨hd.2, c.length_le.trans_lt hd.1.2, λ j, _⟩,
have : c ≠ composition.single k (zero_lt_two.trans_le hd.1.1),
by simp [composition.eq_single_iff_length, ne_of_gt hd.2],
rw composition.ne_single_iff at this,
exact (this j).trans_le (nat.lt_succ_iff.mp hd.1.2)
end
... = ∑ e in comp_partial_sum_source 2 (n+1) n, ∏ (j : fin e.1), r * (a ^ e.2 j * p (e.2 j)) :
begin
symmetry,
apply comp_change_of_variables_sum,
rintros ⟨k, blocks_fun⟩ H,
have K : (comp_change_of_variables 2 (n + 1) n ⟨k, blocks_fun⟩ H).snd.length = k, by simp,
congr' 2; try { rw K },
rw fin.heq_fun_iff K.symm,
assume j,
rw comp_change_of_variables_blocks_fun,
end
... = ∑ j in Ico 2 (n+1), r ^ j * (∑ k in Ico 1 n, a ^ k * p k) ^ j :
begin
rw [comp_partial_sum_source, ← sum_sigma' (Ico 2 (n + 1))
(λ (k : ℕ), (fintype.pi_finset (λ (i : fin k), Ico 1 n) : finset (fin k → ℕ)))
(λ n e, ∏ (j : fin n), r * (a ^ e j * p (e j)))],
apply sum_congr rfl (λ j hj, _),
simp only [← @multilinear_map.mk_pi_algebra_apply ℝ (fin j) _ _ ℝ],
simp only [← multilinear_map.map_sum_finset (multilinear_map.mk_pi_algebra ℝ (fin j) ℝ)
(λ k (m : ℕ), r * (a ^ m * p m))],
simp only [multilinear_map.mk_pi_algebra_apply],
dsimp,
simp [prod_const, ← mul_sum, mul_pow],
end
/-- Second technical lemma to control the growth of coefficients of the inverse. Bound the explicit
expression for `∑_{k<n+1} aᵏ Qₖ` in terms of a sum of powers of the same sum one step before,
in the specific setup we are interesting in, by reducing to the general bound in
`radius_right_inv_pos_of_radius_pos_aux1`. -/
lemma radius_right_inv_pos_of_radius_pos_aux2
{n : ℕ} (hn : 2 ≤ n + 1) (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F)
{r a C : ℝ} (hr : 0 ≤ r) (ha : 0 ≤ a) (hC : 0 ≤ C) (hp : ∀ n, ∥p n∥ ≤ C * r ^ n) :
(∑ k in Ico 1 (n + 1), a ^ k * ∥p.right_inv i k∥) ≤
∥(i.symm : F →L[𝕜] E)∥ * a + ∥(i.symm : F →L[𝕜] E)∥ * C * ∑ k in Ico 2 (n + 1),
(r * ((∑ j in Ico 1 n, a ^ j * ∥p.right_inv i j∥))) ^ k :=
let I := ∥(i.symm : F →L[𝕜] E)∥ in calc
∑ k in Ico 1 (n + 1), a ^ k * ∥p.right_inv i k∥
= a * I + ∑ k in Ico 2 (n + 1), a ^ k * ∥p.right_inv i k∥ :
by simp only [linear_isometry_equiv.norm_map, pow_one, right_inv_coeff_one,
nat.Ico_succ_singleton, sum_singleton, ← sum_Ico_consecutive _ one_le_two hn]
... = a * I + ∑ k in Ico 2 (n + 1), a ^ k *
∥(i.symm : F →L[𝕜] E).comp_continuous_multilinear_map
(∑ c in ({c | 1 < composition.length c}.to_finset : finset (composition k)),
p.comp_along_composition (p.right_inv i) c)∥ :
begin
congr' 1,
apply sum_congr rfl (λ j hj, _),
rw [right_inv_coeff _ _ _ (mem_Ico.1 hj).1, norm_neg],
end
... ≤ a * ∥(i.symm : F →L[𝕜] E)∥ + ∑ k in Ico 2 (n + 1), a ^ k * (I *
(∑ c in ({c | 1 < composition.length c}.to_finset : finset (composition k)),
C * r ^ c.length * ∏ j, ∥p.right_inv i (c.blocks_fun j)∥)) :
begin
apply_rules [add_le_add, le_refl, sum_le_sum (λ j hj, _), mul_le_mul_of_nonneg_left,
pow_nonneg, ha],
apply (continuous_linear_map.norm_comp_continuous_multilinear_map_le _ _).trans,
apply mul_le_mul_of_nonneg_left _ (norm_nonneg _),
apply (norm_sum_le _ _).trans,
apply sum_le_sum (λ c hc, _),
apply (comp_along_composition_norm _ _ _).trans,
apply mul_le_mul_of_nonneg_right (hp _),
exact prod_nonneg (λ j hj, norm_nonneg _),
end
... = I * a + I * C * ∑ k in Ico 2 (n + 1), a ^ k *
(∑ c in ({c | 1 < composition.length c}.to_finset : finset (composition k)),
r ^ c.length * ∏ j, ∥p.right_inv i (c.blocks_fun j)∥) :
begin
simp_rw [mul_assoc C, ← mul_sum, ← mul_assoc, mul_comm _ (∥↑i.symm∥), mul_assoc, ← mul_sum,
← mul_assoc, mul_comm _ C, mul_assoc, ← mul_sum],
ring,
end
... ≤ I * a + I * C * ∑ k in Ico 2 (n+1), (r * ((∑ j in Ico 1 n, a ^ j * ∥p.right_inv i j∥))) ^ k :
begin
apply_rules [add_le_add, le_refl, mul_le_mul_of_nonneg_left, norm_nonneg, hC, mul_nonneg],
simp_rw [mul_pow],
apply radius_right_inv_pos_of_radius_pos_aux1 n (λ k, ∥p.right_inv i k∥)
(λ k, norm_nonneg _) hr ha,
end
/-- If a a formal multilinear series has a positive radius of convergence, then its right inverse
also has a positive radius of convergence. -/
theorem radius_right_inv_pos_of_radius_pos (p : formal_multilinear_series 𝕜 E F) (i : E ≃L[𝕜] F)
(hp : 0 < p.radius) : 0 < (p.right_inv i).radius :=
begin
obtain ⟨C, r, Cpos, rpos, ple⟩ : ∃ C r (hC : 0 < C) (hr : 0 < r), ∀ (n : ℕ), ∥p n∥ ≤ C * r ^ n :=
le_mul_pow_of_radius_pos p hp,
let I := ∥(i.symm : F →L[𝕜] E)∥,
-- choose `a` small enough to make sure that `∑_{k ≤ n} aᵏ Qₖ` will be controllable by
-- induction
obtain ⟨a, apos, ha1, ha2⟩ : ∃ a (apos : 0 < a),
(2 * I * C * r^2 * (I + 1) ^ 2 * a ≤ 1) ∧ (r * (I + 1) * a ≤ 1/2),
{ have : tendsto (λ a, 2 * I * C * r^2 * (I + 1) ^ 2 * a) (𝓝 0)
(𝓝 (2 * I * C * r^2 * (I + 1) ^ 2 * 0)) := tendsto_const_nhds.mul tendsto_id,
have A : ∀ᶠ a in 𝓝 0, 2 * I * C * r^2 * (I + 1) ^ 2 * a < 1,
by { apply (tendsto_order.1 this).2, simp [zero_lt_one] },
have : tendsto (λ a, r * (I + 1) * a) (𝓝 0)
(𝓝 (r * (I + 1) * 0)) := tendsto_const_nhds.mul tendsto_id,
have B : ∀ᶠ a in 𝓝 0, r * (I + 1) * a < 1/2,
by { apply (tendsto_order.1 this).2, simp [zero_lt_one] },
have C : ∀ᶠ a in 𝓝[>] (0 : ℝ), (0 : ℝ) < a,
by { filter_upwards [self_mem_nhds_within] with _ ha using ha },
rcases (C.and ((A.and B).filter_mono inf_le_left)).exists with ⟨a, ha⟩,
exact ⟨a, ha.1, ha.2.1.le, ha.2.2.le⟩ },
-- check by induction that the partial sums are suitably bounded, using the choice of `a` and the
-- inductive control from Lemma `radius_right_inv_pos_of_radius_pos_aux2`.
let S := λ n, ∑ k in Ico 1 n, a ^ k * ∥p.right_inv i k∥,
have IRec : ∀ n, 1 ≤ n → S n ≤ (I + 1) * a,
{ apply nat.le_induction,
{ simp only [S],
rw [Ico_eq_empty_of_le (le_refl 1), sum_empty],
exact mul_nonneg (add_nonneg (norm_nonneg _) zero_le_one) apos.le },
{ assume n one_le_n hn,
have In : 2 ≤ n + 1, by linarith,
have Snonneg : 0 ≤ S n :=
sum_nonneg (λ x hx, mul_nonneg (pow_nonneg apos.le _) (norm_nonneg _)),
have rSn : r * S n ≤ 1/2 := calc
r * S n ≤ r * ((I+1) * a) : mul_le_mul_of_nonneg_left hn rpos.le
... ≤ 1/2 : by rwa [← mul_assoc],
calc S (n + 1) ≤ I * a + I * C * ∑ k in Ico 2 (n + 1), (r * S n)^k :
radius_right_inv_pos_of_radius_pos_aux2 In p i rpos.le apos.le Cpos.le ple
... = I * a + I * C * (((r * S n) ^ 2 - (r * S n) ^ (n + 1)) / (1 - r * S n)) :
by { rw geom_sum_Ico' _ In, exact ne_of_lt (rSn.trans_lt (by norm_num)) }
... ≤ I * a + I * C * ((r * S n) ^ 2 / (1/2)) :
begin
apply_rules [add_le_add, le_refl, mul_le_mul_of_nonneg_left, mul_nonneg, norm_nonneg,
Cpos.le],
refine div_le_div (sq_nonneg _) _ (by norm_num) (by linarith),
simp only [sub_le_self_iff],
apply pow_nonneg (mul_nonneg rpos.le Snonneg),
end
... = I * a + 2 * I * C * (r * S n) ^ 2 : by ring
... ≤ I * a + 2 * I * C * (r * ((I + 1) * a)) ^ 2 :
by apply_rules [add_le_add, le_refl, mul_le_mul_of_nonneg_left, mul_nonneg, norm_nonneg,
Cpos.le, zero_le_two, pow_le_pow_of_le_left, rpos.le]
... = (I + 2 * I * C * r^2 * (I + 1) ^ 2 * a) * a : by ring
... ≤ (I + 1) * a :
by apply_rules [mul_le_mul_of_nonneg_right, apos.le, add_le_add, le_refl] } },
-- conclude that all coefficients satisfy `aⁿ Qₙ ≤ (I + 1) a`.
let a' : nnreal := ⟨a, apos.le⟩,
suffices H : (a' : ennreal) ≤ (p.right_inv i).radius,
by { apply lt_of_lt_of_le _ H, exact_mod_cast apos },
apply le_radius_of_bound _ ((I + 1) * a) (λ n, _),
by_cases hn : n = 0,
{ have : ∥p.right_inv i n∥ = ∥p.right_inv i 0∥, by congr; try { rw hn },
simp only [this, norm_zero, zero_mul, right_inv_coeff_zero],
apply_rules [mul_nonneg, add_nonneg, norm_nonneg, zero_le_one, apos.le] },
{ have one_le_n : 1 ≤ n := bot_lt_iff_ne_bot.2 hn,
calc ∥p.right_inv i n∥ * ↑a' ^ n = a ^ n * ∥p.right_inv i n∥ : mul_comm _ _
... ≤ ∑ k in Ico 1 (n + 1), a ^ k * ∥p.right_inv i k∥ :
begin
have : ∀ k ∈ Ico 1 (n + 1), 0 ≤ a ^ k * ∥p.right_inv i k∥ :=
λ k hk, mul_nonneg (pow_nonneg apos.le _) (norm_nonneg _),
exact single_le_sum this (by simp [one_le_n]),
end
... ≤ (I + 1) * a : IRec (n + 1) (by dec_trivial) }
end
end formal_multilinear_series
|
2bcd9bd35bff1e6b62b528daecff8e0f3bbb8988 | b7f22e51856f4989b970961f794f1c435f9b8f78 | /library/data/set/function.lean | e8263659f652ab90e938f8b04bdf6ad1c22df489 | [
"Apache-2.0"
] | permissive | soonhokong/lean | cb8aa01055ffe2af0fb99a16b4cda8463b882cd1 | 38607e3eb57f57f77c0ac114ad169e9e4262e24f | refs/heads/master | 1,611,187,284,081 | 1,450,766,737,000 | 1,476,122,547,000 | 11,513,992 | 2 | 0 | null | 1,401,763,102,000 | 1,374,182,235,000 | C++ | UTF-8 | Lean | false | false | 13,703 | lean | /-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Jeremy Avigad, Andrew Zipperer, Haitao Zhang
Functions between subsets of finite types.
-/
import .basic
open function eq.ops
namespace set
variables {X Y Z : Type}
/- preimages -/
definition preimage {A B:Type} (f : A → B) (Y : set B) : set A := { x | f x ∈ Y }
notation f ` '- ` s := preimage f s
theorem mem_preimage_iff (f : X → Y) (a : set Y) (x : X) :
f x ∈ a ↔ x ∈ f '- a :=
!iff.refl
theorem mem_preimage {f : X → Y} {a : set Y} {x : X} (H : f x ∈ a) :
x ∈ f '- a := H
theorem mem_of_mem_preimage {f : X → Y} {a : set Y} {x : X} (H : x ∈ f '- a) :
f x ∈ a :=
proof H qed
theorem preimage_comp (f : Y → Z) (g : X → Y) (a : set Z) :
(f ∘ g) '- a = g '- (f '- a) :=
ext (take x, !iff.refl)
lemma image_subset_iff {A B : Type} {f : A → B} {X : set A} {Y : set B} :
f ' X ⊆ Y ↔ X ⊆ f '- Y :=
@bounded_forall_image_iff A B f X Y
theorem preimage_subset {a b : set Y} (f : X → Y) (H : a ⊆ b) :
f '- a ⊆ f '- b :=
λ x H', proof @H (f x) H' qed
theorem preimage_id (s : set Y) : (λx, x) '- s = s :=
ext (take x, !iff.refl)
theorem preimage_union (f : X → Y) (s t : set Y) :
f '- (s ∪ t) = f '- s ∪ f '- t :=
ext (take x, !iff.refl)
theorem preimage_inter (f : X → Y) (s t : set Y) :
f '- (s ∩ t) = f '- s ∩ f '- t :=
ext (take x, !iff.refl)
theorem preimage_compl (f : X → Y) (s : set Y) :
f '- (-s) = -(f '- s) :=
ext (take x, !iff.refl)
theorem preimage_diff (f : X → Y) (s t : set Y) :
f '- (s \ t) = f '- s \ f '- t :=
ext (take x, !iff.refl)
theorem image_preimage_subset (f : X → Y) (s : set Y) :
f ' (f '- s) ⊆ s :=
take y, suppose y ∈ f ' (f '- s),
obtain x [xfis fxeqy], from this,
show y ∈ s, by rewrite -fxeqy; exact xfis
theorem subset_preimage_image (s : set X) (f : X → Y) :
s ⊆ f '- (f ' s) :=
take x, suppose x ∈ s,
show f x ∈ f ' s, from mem_image_of_mem f this
theorem inter_preimage_subset (s : set X) (t : set Y) (f : X → Y) :
s ∩ f '- t ⊆ f '- (f ' s ∩ t) :=
take x, assume H : x ∈ s ∩ f '- t,
mem_preimage (show f x ∈ f ' s ∩ t,
from and.intro (mem_image_of_mem f (and.left H)) (mem_of_mem_preimage (and.right H)))
theorem union_preimage_subset (s : set X) (t : set Y) (f : X → Y) :
s ∪ f '- t ⊆ f '- (f ' s ∪ t) :=
take x, assume H : x ∈ s ∪ f '- t,
mem_preimage (show f x ∈ f ' s ∪ t,
from or.elim H
(suppose x ∈ s, or.inl (mem_image_of_mem f this))
(suppose x ∈ f '- t, or.inr (mem_of_mem_preimage this)))
theorem image_inter (f : X → Y) (s : set X) (t : set Y) :
f ' s ∩ t = f ' (s ∩ f '- t) :=
ext (take y, iff.intro
(suppose y ∈ f ' s ∩ t,
obtain [x [xs fxeqy]] yt, from this,
have x ∈ s ∩ f '- t,
from and.intro xs (mem_preimage (show f x ∈ t, by rewrite fxeqy; exact yt)),
mem_image this fxeqy)
(suppose y ∈ f ' (s ∩ f '- t),
obtain x [[xs xfit] fxeqy], from this,
and.intro (mem_image xs fxeqy)
(show y ∈ t, by rewrite -fxeqy; exact mem_of_mem_preimage xfit)))
theorem image_union_supset (f : X → Y) (s : set X) (t : set Y) :
f ' s ∪ t ⊇ f ' (s ∪ f '- t) :=
take y, assume H,
obtain x [xmem fxeqy], from H,
or.elim xmem
(suppose x ∈ s, or.inl (mem_image this fxeqy))
(suppose x ∈ f '- t, or.inr (show y ∈ t, by rewrite -fxeqy; exact mem_of_mem_preimage this))
/- maps to -/
definition maps_to [reducible] (f : X → Y) (a : set X) (b : set Y) : Prop := ∀⦃x⦄, x ∈ a → f x ∈ b
theorem maps_to_of_eq_on {f1 f2 : X → Y} {a : set X} {b : set Y} (eq_on_a : eq_on f1 f2 a)
(maps_to_f1 : maps_to f1 a b) :
maps_to f2 a b :=
take x,
assume xa : x ∈ a,
have H : f1 x ∈ b, from maps_to_f1 xa,
show f2 x ∈ b, from eq_on_a xa ▸ H
theorem maps_to_comp {g : Y → Z} {f : X → Y} {a : set X} {b : set Y} {c : set Z}
(H1 : maps_to g b c) (H2 : maps_to f a b) : maps_to (g ∘ f) a c :=
take x, assume H : x ∈ a, H1 (H2 H)
theorem maps_to_univ_univ (f : X → Y) : maps_to f univ univ :=
take x, assume H, trivial
theorem image_subset_of_maps_to_of_subset {f : X → Y} {a : set X} {b : set Y} (mfab : maps_to f a b)
{c : set X} (csuba : c ⊆ a) :
f ' c ⊆ b :=
take y,
suppose y ∈ f ' c,
obtain x [(xc : x ∈ c) (yeq : f x = y)], from this,
have x ∈ a, from csuba `x ∈ c`,
have f x ∈ b, from mfab this,
show y ∈ b, from yeq ▸ this
theorem image_subset_of_maps_to {f : X → Y} {a : set X} {b : set Y} (mfab : maps_to f a b) :
f ' a ⊆ b :=
image_subset_of_maps_to_of_subset mfab (subset.refl a)
/- injectivity -/
definition inj_on [reducible] (f : X → Y) (a : set X) : Prop :=
∀⦃x1 x2 : X⦄, x1 ∈ a → x2 ∈ a → f x1 = f x2 → x1 = x2
theorem inj_on_empty (f : X → Y) : inj_on f ∅ :=
take x₁ x₂, assume H₁ H₂ H₃, false.elim H₁
theorem inj_on_of_eq_on {f1 f2 : X → Y} {a : set X} (eq_f1_f2 : eq_on f1 f2 a)
(inj_f1 : inj_on f1 a) :
inj_on f2 a :=
take x1 x2 : X,
assume ax1 : x1 ∈ a,
assume ax2 : x2 ∈ a,
assume H : f2 x1 = f2 x2,
have H' : f1 x1 = f1 x2, from eq_f1_f2 ax1 ⬝ H ⬝ (eq_f1_f2 ax2)⁻¹,
show x1 = x2, from inj_f1 ax1 ax2 H'
theorem inj_on_comp {g : Y → Z} {f : X → Y} {a : set X} {b : set Y}
(fab : maps_to f a b) (Hg : inj_on g b) (Hf: inj_on f a) :
inj_on (g ∘ f) a :=
take x1 x2 : X,
assume x1a : x1 ∈ a,
assume x2a : x2 ∈ a,
have fx1b : f x1 ∈ b, from fab x1a,
have fx2b : f x2 ∈ b, from fab x2a,
assume H1 : g (f x1) = g (f x2),
have H2 : f x1 = f x2, from Hg fx1b fx2b H1,
show x1 = x2, from Hf x1a x2a H2
theorem inj_on_of_inj_on_of_subset {f : X → Y} {a b : set X} (H1 : inj_on f b) (H2 : a ⊆ b) :
inj_on f a :=
take x1 x2 : X, assume (x1a : x1 ∈ a) (x2a : x2 ∈ a),
assume H : f x1 = f x2,
show x1 = x2, from H1 (H2 x1a) (H2 x2a) H
lemma injective_iff_inj_on_univ {f : X → Y} : injective f ↔ inj_on f univ :=
iff.intro
(assume H, take x₁ x₂, assume ax₁ ax₂, H x₁ x₂)
(assume H : inj_on f univ,
take x₁ x₂ Heq,
show x₁ = x₂, from H trivial trivial Heq)
/- surjectivity -/
definition surj_on [reducible] (f : X → Y) (a : set X) (b : set Y) : Prop := b ⊆ f ' a
theorem surj_on_of_eq_on {f1 f2 : X → Y} {a : set X} {b : set Y} (eq_f1_f2 : eq_on f1 f2 a)
(surj_f1 : surj_on f1 a b) :
surj_on f2 a b :=
take y, assume H : y ∈ b,
obtain x (H1 : x ∈ a ∧ f1 x = y), from surj_f1 H,
have H2 : x ∈ a, from and.left H1,
have H3 : f2 x = y, from (eq_f1_f2 H2)⁻¹ ⬝ and.right H1,
exists.intro x (and.intro H2 H3)
theorem surj_on_comp {g : Y → Z} {f : X → Y} {a : set X} {b : set Y} {c : set Z}
(Hg : surj_on g b c) (Hf: surj_on f a b) :
surj_on (g ∘ f) a c :=
take z,
assume zc : z ∈ c,
obtain y (H1 : y ∈ b ∧ g y = z), from Hg zc,
obtain x (H2 : x ∈ a ∧ f x = y), from Hf (and.left H1),
show ∃x, x ∈ a ∧ g (f x) = z, from
exists.intro x
(and.intro
(and.left H2)
(calc
g (f x) = g y : {and.right H2}
... = z : and.right H1))
lemma surjective_iff_surj_on_univ {f : X → Y} : surjective f ↔ surj_on f univ univ :=
iff.intro
(assume H, take y, assume Hy,
obtain x Hx, from H y,
mem_image trivial Hx)
(assume H, take y,
obtain x H1x H2x, from H y trivial,
exists.intro x H2x)
lemma image_eq_of_maps_to_of_surj_on {f : X → Y} {a : set X} {b : set Y}
(H1 : maps_to f a b) (H2 : surj_on f a b) :
f ' a = b :=
eq_of_subset_of_subset (image_subset_of_maps_to H1) H2
/- bijectivity -/
definition bij_on [reducible] (f : X → Y) (a : set X) (b : set Y) : Prop :=
maps_to f a b ∧ inj_on f a ∧ surj_on f a b
lemma maps_to_of_bij_on {f : X → Y} {a : set X} {b : set Y} (H : bij_on f a b) :
maps_to f a b :=
and.left H
lemma inj_on_of_bij_on {f : X → Y} {a : set X} {b : set Y} (H : bij_on f a b) :
inj_on f a :=
and.left (and.right H)
lemma surj_on_of_bij_on {f : X → Y} {a : set X} {b : set Y} (H : bij_on f a b) :
surj_on f a b :=
and.right (and.right H)
lemma bij_on.mk {f : X → Y} {a : set X} {b : set Y}
(H₁ : maps_to f a b) (H₂ : inj_on f a) (H₃ : surj_on f a b) :
bij_on f a b :=
and.intro H₁ (and.intro H₂ H₃)
theorem bij_on_of_eq_on {f1 f2 : X → Y} {a : set X} {b : set Y} (eqf : eq_on f1 f2 a)
(H : bij_on f1 a b) : bij_on f2 a b :=
match H with and.intro Hmap (and.intro Hinj Hsurj) :=
and.intro
(maps_to_of_eq_on eqf Hmap)
(and.intro
(inj_on_of_eq_on eqf Hinj)
(surj_on_of_eq_on eqf Hsurj))
end
lemma image_eq_of_bij_on {f : X → Y} {a : set X} {b : set Y} (bfab : bij_on f a b) :
f ' a = b :=
image_eq_of_maps_to_of_surj_on (and.left bfab) (and.right (and.right bfab))
theorem bij_on_comp {g : Y → Z} {f : X → Y} {a : set X} {b : set Y} {c : set Z}
(Hg : bij_on g b c) (Hf: bij_on f a b) :
bij_on (g ∘ f) a c :=
match Hg with and.intro Hgmap (and.intro Hginj Hgsurj) :=
match Hf with and.intro Hfmap (and.intro Hfinj Hfsurj) :=
and.intro
(maps_to_comp Hgmap Hfmap)
(and.intro
(inj_on_comp Hfmap Hginj Hfinj)
(surj_on_comp Hgsurj Hfsurj))
end
end
lemma bijective_iff_bij_on_univ {f : X → Y} : bijective f ↔ bij_on f univ univ :=
iff.intro
(assume H,
obtain Hinj Hsurj, from H,
and.intro (maps_to_univ_univ f)
(and.intro
(iff.mp !injective_iff_inj_on_univ Hinj)
(iff.mp !surjective_iff_surj_on_univ Hsurj)))
(assume H,
obtain Hmaps Hinj Hsurj, from H,
(and.intro
(iff.mpr !injective_iff_inj_on_univ Hinj)
(iff.mpr !surjective_iff_surj_on_univ Hsurj)))
/- left inverse -/
-- g is a left inverse to f on a
definition left_inv_on [reducible] (g : Y → X) (f : X → Y) (a : set X) : Prop :=
∀₀ x ∈ a, g (f x) = x
theorem left_inv_on_of_eq_on_left {g1 g2 : Y → X} {f : X → Y} {a : set X} {b : set Y}
(fab : maps_to f a b) (eqg : eq_on g1 g2 b) (H : left_inv_on g1 f a) : left_inv_on g2 f a :=
take x,
assume xa : x ∈ a,
calc
g2 (f x) = g1 (f x) : (eqg (fab xa))⁻¹
... = x : H xa
theorem left_inv_on_of_eq_on_right {g : Y → X} {f1 f2 : X → Y} {a : set X}
(eqf : eq_on f1 f2 a) (H : left_inv_on g f1 a) : left_inv_on g f2 a :=
take x,
assume xa : x ∈ a,
calc
g (f2 x) = g (f1 x) : {(eqf xa)⁻¹}
... = x : H xa
theorem inj_on_of_left_inv_on {g : Y → X} {f : X → Y} {a : set X} (H : left_inv_on g f a) :
inj_on f a :=
take x1 x2,
assume x1a : x1 ∈ a,
assume x2a : x2 ∈ a,
assume H1 : f x1 = f x2,
calc
x1 = g (f x1) : H x1a
... = g (f x2) : H1
... = x2 : H x2a
theorem left_inv_on_comp {f' : Y → X} {g' : Z → Y} {g : Y → Z} {f : X → Y}
{a : set X} {b : set Y} (fab : maps_to f a b)
(Hf : left_inv_on f' f a) (Hg : left_inv_on g' g b) : left_inv_on (f' ∘ g') (g ∘ f) a :=
take x : X,
assume xa : x ∈ a,
have fxb : f x ∈ b, from fab xa,
calc
f' (g' (g (f x))) = f' (f x) : Hg fxb
... = x : Hf xa
/- right inverse -/
-- g is a right inverse to f on a
definition right_inv_on [reducible] (g : Y → X) (f : X → Y) (b : set Y) : Prop :=
left_inv_on f g b
theorem right_inv_on_of_eq_on_left {g1 g2 : Y → X} {f : X → Y} {a : set X} {b : set Y}
(eqg : eq_on g1 g2 b) (H : right_inv_on g1 f b) : right_inv_on g2 f b :=
left_inv_on_of_eq_on_right eqg H
theorem right_inv_on_of_eq_on_right {g : Y → X} {f1 f2 : X → Y} {a : set X} {b : set Y}
(gba : maps_to g b a) (eqf : eq_on f1 f2 a) (H : right_inv_on g f1 b) : right_inv_on g f2 b :=
left_inv_on_of_eq_on_left gba eqf H
theorem surj_on_of_right_inv_on {g : Y → X} {f : X → Y} {a : set X} {b : set Y}
(gba : maps_to g b a) (H : right_inv_on g f b) :
surj_on f a b :=
take y,
assume yb : y ∈ b,
have gya : g y ∈ a, from gba yb,
have H1 : f (g y) = y, from H yb,
exists.intro (g y) (and.intro gya H1)
theorem right_inv_on_comp {f' : Y → X} {g' : Z → Y} {g : Y → Z} {f : X → Y}
{c : set Z} {b : set Y} (g'cb : maps_to g' c b)
(Hf : right_inv_on f' f b) (Hg : right_inv_on g' g c) : right_inv_on (f' ∘ g') (g ∘ f) c :=
left_inv_on_comp g'cb Hg Hf
theorem right_inv_on_of_inj_on_of_left_inv_on {f : X → Y} {g : Y → X} {a : set X} {b : set Y}
(fab : maps_to f a b) (gba : maps_to g b a) (injf : inj_on f a) (lfg : left_inv_on f g b) :
right_inv_on f g a :=
take x, assume xa : x ∈ a,
have H : f (g (f x)) = f x, from lfg (fab xa),
injf (gba (fab xa)) xa H
theorem eq_on_of_left_inv_of_right_inv {g1 g2 : Y → X} {f : X → Y} {a : set X} {b : set Y}
(g2ba : maps_to g2 b a) (Hg1 : left_inv_on g1 f a) (Hg2 : right_inv_on g2 f b) : eq_on g1 g2 b :=
take y,
assume yb : y ∈ b,
calc
g1 y = g1 (f (g2 y)) : {(Hg2 yb)⁻¹}
... = g2 y : Hg1 (g2ba yb)
theorem left_inv_on_of_surj_on_right_inv_on {f : X → Y} {g : Y → X} {a : set X} {b : set Y}
(surjf : surj_on f a b) (rfg : right_inv_on f g a) :
left_inv_on f g b :=
take y, assume yb : y ∈ b,
obtain x (xa : x ∈ a) (Hx : f x = y), from surjf yb,
calc
f (g y) = f (g (f x)) : Hx
... = f x : rfg xa
... = y : Hx
/- inverses -/
-- g is an inverse to f viewed as a map from a to b
definition inv_on [reducible] (g : Y → X) (f : X → Y) (a : set X) (b : set Y) : Prop :=
left_inv_on g f a ∧ right_inv_on g f b
theorem bij_on_of_inv_on {g : Y → X} {f : X → Y} {a : set X} {b : set Y} (fab : maps_to f a b)
(gba : maps_to g b a) (H : inv_on g f a b) : bij_on f a b :=
and.intro fab
(and.intro
(inj_on_of_left_inv_on (and.left H))
(surj_on_of_right_inv_on gba (and.right H)))
end set
|
13b51d63be9db8173cadfd1119e7f9b4caed2715 | 86f6f4f8d827a196a32bfc646234b73328aeb306 | /examples/logic/unnamed_1156.lean | 7d7f47a1256c60af2eb6d89651ba75b6cad5b4c0 | [] | no_license | jamescheuk91/mathematics_in_lean | 09f1f87d2b0dce53464ff0cbe592c568ff59cf5e | 4452499264e2975bca2f42565c0925506ba5dda3 | refs/heads/master | 1,679,716,410,967 | 1,613,957,947,000 | 1,613,957,947,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 204 | lean | import data.real.basic
variables (f : ℝ → ℝ) (a b : ℝ)
-- BEGIN
example (h : monotone f) (h' : f a < f b) : a < b :=
sorry
example (h : a ≤ b) (h' : f b < f a) : ¬ monotone f :=
sorry
-- END |
ad20c558d7667e9d04c282fde0d54e73843ca3ce | a45212b1526d532e6e83c44ddca6a05795113ddc | /src/set_theory/lists.lean | f969c7c914ec1f4ec8241d27858b5c95b0b97505 | [
"Apache-2.0"
] | permissive | fpvandoorn/mathlib | b21ab4068db079cbb8590b58fda9cc4bc1f35df4 | b3433a51ea8bc07c4159c1073838fc0ee9b8f227 | refs/heads/master | 1,624,791,089,608 | 1,556,715,231,000 | 1,556,715,231,000 | 165,722,980 | 5 | 0 | Apache-2.0 | 1,552,657,455,000 | 1,547,494,646,000 | Lean | UTF-8 | Lean | false | false | 11,688 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Mario Carneiro
A computable model of hereditarily finite sets with atoms
(ZFA without infinity). This is useful for calculations in naive
set theory.
-/
import tactic.interactive data.list.basic data.sigma
variables {α : Type*}
@[derive decidable_eq]
inductive {u} lists' (α : Type u) : bool → Type u
| atom : α → lists' ff
| nil {} : lists' tt
| cons' {b} : lists' b → lists' tt → lists' tt
def lists (α : Type*) := Σ b, lists' α b
namespace lists'
def cons : lists α → lists' α tt → lists' α tt
| ⟨b, a⟩ l := cons' a l
@[simp] def to_list : ∀ {b}, lists' α b → list (lists α)
| _ (atom a) := []
| _ nil := []
| _ (cons' a l) := ⟨_, a⟩ :: l.to_list
@[simp] theorem to_list_cons (a : lists α) (l) :
to_list (cons a l) = a :: l.to_list :=
by cases a; simp [cons]
@[simp] def of_list : list (lists α) → lists' α tt
| [] := nil
| (a :: l) := cons a (of_list l)
@[simp] theorem to_of_list (l : list (lists α)) : to_list (of_list l) = l :=
by induction l; simp *
@[simp] theorem of_to_list : ∀ (l : lists' α tt), of_list (to_list l) = l :=
suffices ∀ b (h : tt = b) (l : lists' α b),
let l' : lists' α tt := by rw h; exact l in
of_list (to_list l') = l', from this _ rfl,
λ b h l, begin
induction l, {cases h}, {exact rfl},
case lists'.cons' : b a l IH₁ IH₂ {
intro, change l' with cons' a l,
simpa [cons] using IH₂ rfl }
end
end lists'
mutual inductive lists.equiv, lists'.subset
with lists.equiv : lists α → lists α → Prop
| refl (l) : lists.equiv l l
| antisymm {l₁ l₂ : lists' α tt} :
lists'.subset l₁ l₂ → lists'.subset l₂ l₁ → lists.equiv ⟨_, l₁⟩ ⟨_, l₂⟩
with lists'.subset : lists' α tt → lists' α tt → Prop
| nil {l} : lists'.subset lists'.nil l
| cons {a a' l l'} : lists.equiv a a' → a' ∈ lists'.to_list l' →
lists'.subset l l' → lists'.subset (lists'.cons a l) l'
local infix ~ := equiv
namespace lists'
instance : has_subset (lists' α tt) := ⟨lists'.subset⟩
instance {b} : has_mem (lists α) (lists' α b) :=
⟨λ a l, ∃ a' ∈ l.to_list, a ~ a'⟩
theorem mem_def {b a} {l : lists' α b} :
a ∈ l ↔ ∃ a' ∈ l.to_list, a ~ a' := iff.rfl
@[simp] theorem mem_cons {a y l} : a ∈ @cons α y l ↔ a ~ y ∨ a ∈ l :=
by simp [mem_def, or_and_distrib_right, exists_or_distrib]
theorem cons_subset {a} {l₁ l₂ : lists' α tt} :
lists'.cons a l₁ ⊆ l₂ ↔ a ∈ l₂ ∧ l₁ ⊆ l₂ :=
begin
refine ⟨λ h, _, λ ⟨⟨a', m, e⟩, s⟩, subset.cons e m s⟩,
generalize_hyp h' : lists'.cons a l₁ = l₁' at h,
cases h with l a' a'' l l' e m s, {cases a, cases h'},
cases a, cases a', cases h', exact ⟨⟨_, m, e⟩, s⟩
end
theorem of_list_subset {l₁ l₂ : list (lists α)} (h : l₁ ⊆ l₂) :
lists'.of_list l₁ ⊆ lists'.of_list l₂ :=
begin
induction l₁, {exact subset.nil},
refine subset.cons (equiv.refl _) _ (l₁_ih (list.subset_of_cons_subset h)),
simp at h, simp [h]
end
@[refl] theorem subset.refl {l : lists' α tt} : l ⊆ l :=
by rw ← lists'.of_to_list l; exact
of_list_subset (list.subset.refl _)
theorem subset_nil {l : lists' α tt} :
l ⊆ lists'.nil → l = lists'.nil :=
begin
rw ← of_to_list l,
induction to_list l; intro h, {refl},
rcases cons_subset.1 h with ⟨⟨_, ⟨⟩, _⟩, _⟩
end
theorem mem_of_subset' {a} {l₁ l₂ : lists' α tt}
(s : l₁ ⊆ l₂) (h : a ∈ l₁.to_list) : a ∈ l₂ :=
begin
induction s with _ a a' l l' e m s IH, {cases h},
simp at h, rcases h with rfl|h,
exacts [⟨_, m, e⟩, IH h]
end
theorem subset_def {l₁ l₂ : lists' α tt} :
l₁ ⊆ l₂ ↔ ∀ a ∈ l₁.to_list, a ∈ l₂ :=
⟨λ H a, mem_of_subset' H, λ H, begin
rw ← of_to_list l₁,
revert H, induction to_list l₁; intro,
{ exact subset.nil },
{ simp at H, exact cons_subset.2 ⟨H.1, ih H.2⟩ }
end⟩
end lists'
namespace lists
@[pattern] def atom (a : α) : lists α := ⟨_, lists'.atom a⟩
@[pattern] def of' (l : lists' α tt) : lists α := ⟨_, l⟩
@[simp] def to_list : lists α → list (lists α)
| ⟨b, l⟩ := l.to_list
def is_list (l : lists α) : Prop := l.1
def of_list (l : list (lists α)) : lists α := of' (lists'.of_list l)
theorem is_list_to_list (l : list (lists α)) : is_list (of_list l) :=
eq.refl _
theorem to_of_list (l : list (lists α)) : to_list (of_list l) = l :=
by simp [of_list, of']
theorem of_to_list : ∀ {l : lists α}, is_list l → of_list (to_list l) = l
| ⟨tt, l⟩ _ := by simp [of_list, of']
instance [decidable_eq α] : decidable_eq (lists α) :=
by unfold lists; apply_instance
instance [has_sizeof α] : has_sizeof (lists α) :=
by unfold lists; apply_instance
def induction_mut (C : lists α → Sort*) (D : lists' α tt → Sort*)
(C0 : ∀ a, C (atom a)) (C1 : ∀ l, D l → C (of' l))
(D0 : D lists'.nil) (D1 : ∀ a l, C a → D l → D (lists'.cons a l)) :
pprod (∀ l, C l) (∀ l, D l) :=
begin
suffices : ∀ {b} (l : lists' α b),
pprod (C ⟨_, l⟩) (match b, l with
| tt, l := D l
| ff, l := punit
end),
{ exact ⟨λ ⟨b, l⟩, (this _).1, λ l, (this l).2⟩ },
intros, induction l with a b a l IH₁ IH₂,
{ exact ⟨C0 _, ⟨⟩⟩ },
{ exact ⟨C1 _ D0, D0⟩ },
{ suffices, {exact ⟨C1 _ this, this⟩},
exact D1 ⟨_, _⟩ _ IH₁.1 IH₂.2 }
end
def mem (a : lists α) : lists α → Prop
| ⟨ff, l⟩ := false
| ⟨tt, l⟩ := a ∈ l
instance : has_mem (lists α) (lists α) := ⟨mem⟩
theorem is_list_of_mem {a : lists α} : ∀ {l : lists α}, a ∈ l → is_list l
| ⟨_, lists'.nil⟩ _ := rfl
| ⟨_, lists'.cons' _ _⟩ _ := rfl
theorem equiv.antisymm_iff {l₁ l₂ : lists' α tt} :
of' l₁ ~ of' l₂ ↔ l₁ ⊆ l₂ ∧ l₂ ⊆ l₁ :=
begin
refine ⟨λ h, _, λ ⟨h₁, h₂⟩, equiv.antisymm h₁ h₂⟩,
cases h with _ _ _ h₁ h₂,
{ simp [lists'.subset.refl] }, { exact ⟨h₁, h₂⟩ }
end
attribute [refl] equiv.refl
theorem equiv_atom {a} {l : lists α} : atom a ~ l ↔ atom a = l :=
⟨λ h, by cases h; refl, λ h, h ▸ equiv.refl _⟩
theorem equiv.symm {l₁ l₂ : lists α} (h : l₁ ~ l₂) : l₂ ~ l₁ :=
by cases h with _ _ _ h₁ h₂; [refl, exact equiv.antisymm h₂ h₁]
theorem equiv.trans : ∀ {l₁ l₂ l₃ : lists α}, l₁ ~ l₂ → l₂ ~ l₃ → l₁ ~ l₃ :=
begin
let trans := λ (l₁ : lists α), ∀ ⦃l₂ l₃⦄, l₁ ~ l₂ → l₂ ~ l₃ → l₁ ~ l₃,
suffices : pprod (∀ l₁, trans l₁)
(∀ (l : lists' α tt) (l' ∈ l.to_list), trans l'), {exact this.1},
apply induction_mut,
{ intros a l₂ l₃ h₁ h₂,
rwa ← equiv_atom.1 h₁ at h₂ },
{ intros l₁ IH l₂ l₃ h₁ h₂,
cases h₁ with _ _ l₂, {exact h₂},
cases h₂ with _ _ l₃, {exact h₁},
cases equiv.antisymm_iff.1 h₁ with hl₁ hr₁,
cases equiv.antisymm_iff.1 h₂ with hl₂ hr₂,
apply equiv.antisymm_iff.2; split; apply lists'.subset_def.2,
{ intros a₁ m₁,
rcases lists'.mem_of_subset' hl₁ m₁ with ⟨a₂, m₂, e₁₂⟩,
rcases lists'.mem_of_subset' hl₂ m₂ with ⟨a₃, m₃, e₂₃⟩,
exact ⟨a₃, m₃, IH _ m₁ e₁₂ e₂₃⟩ },
{ intros a₃ m₃,
rcases lists'.mem_of_subset' hr₂ m₃ with ⟨a₂, m₂, e₃₂⟩,
rcases lists'.mem_of_subset' hr₁ m₂ with ⟨a₁, m₁, e₂₁⟩,
exact ⟨a₁, m₁, (IH _ m₁ e₂₁.symm e₃₂.symm).symm⟩ } },
{ rintro _ ⟨⟩ },
{ intros a l IH₁ IH₂, simpa [IH₁] using IH₂ }
end
instance : setoid (lists α) :=
⟨(~), equiv.refl, @equiv.symm _, @equiv.trans _⟩
section decidable
@[simp] def equiv.decidable_meas :
(psum (Σ' (l₁ : lists α), lists α) $
psum (Σ' (l₁ : lists' α tt), lists' α tt)
Σ' (a : lists α), lists' α tt) → ℕ
| (psum.inl ⟨l₁, l₂⟩) := sizeof l₁ + sizeof l₂
| (psum.inr $ psum.inl ⟨l₁, l₂⟩) := sizeof l₁ + sizeof l₂
| (psum.inr $ psum.inr ⟨l₁, l₂⟩) := sizeof l₁ + sizeof l₂
local attribute [-simp] add_comm add_assoc
open well_founded_tactics
theorem sizeof_pos {b} (l : lists' α b) : 0 < sizeof l :=
by cases l; {unfold_sizeof, trivial_nat_lt}
theorem lt_sizeof_cons' {b} (a : lists' α b) (l) :
sizeof (⟨b, a⟩ : lists α) < sizeof (lists'.cons' a l) :=
by {unfold_sizeof, apply sizeof_pos}
@[instance] mutual def equiv.decidable, subset.decidable, mem.decidable [decidable_eq α]
with equiv.decidable : ∀ l₁ l₂ : lists α, decidable (l₁ ~ l₂)
| ⟨ff, l₁⟩ ⟨ff, l₂⟩ := decidable_of_iff' (l₁ = l₂) $
by cases l₁; refine equiv_atom.trans (by simp [atom])
| ⟨ff, l₁⟩ ⟨tt, l₂⟩ := is_false $ by rintro ⟨⟩
| ⟨tt, l₁⟩ ⟨ff, l₂⟩ := is_false $ by rintro ⟨⟩
| ⟨tt, l₁⟩ ⟨tt, l₂⟩ := begin
haveI :=
have sizeof l₁ + sizeof l₂ <
sizeof (⟨tt, l₁⟩ : lists α) + sizeof (⟨tt, l₂⟩ : lists α),
by default_dec_tac,
subset.decidable l₁ l₂,
haveI :=
have sizeof l₂ + sizeof l₁ <
sizeof (⟨tt, l₁⟩ : lists α) + sizeof (⟨tt, l₂⟩ : lists α),
by default_dec_tac,
subset.decidable l₂ l₁,
exact decidable_of_iff' _ equiv.antisymm_iff,
end
with subset.decidable : ∀ l₁ l₂ : lists' α tt, decidable (l₁ ⊆ l₂)
| lists'.nil l₂ := is_true subset.nil
| (@lists'.cons' _ b a l₁) l₂ := begin
haveI :=
have sizeof (⟨b, a⟩ : lists α) + sizeof l₂ <
sizeof (lists'.cons' a l₁) + sizeof l₂,
from add_lt_add_right (lt_sizeof_cons' _ _) _,
mem.decidable ⟨b, a⟩ l₂,
haveI :=
have sizeof l₁ + sizeof l₂ <
sizeof (lists'.cons' a l₁) + sizeof l₂,
by default_dec_tac,
subset.decidable l₁ l₂,
exact decidable_of_iff' _ (@lists'.cons_subset _ ⟨_, _⟩ _ _)
end
with mem.decidable : ∀ (a : lists α) (l : lists' α tt), decidable (a ∈ l)
| a lists'.nil := is_false $ by rintro ⟨_, ⟨⟩, _⟩
| a (lists'.cons' b l₂) := begin
haveI :=
have sizeof a + sizeof (⟨_, b⟩ : lists α) <
sizeof a + sizeof (lists'.cons' b l₂),
from add_lt_add_left (lt_sizeof_cons' _ _) _,
equiv.decidable a ⟨_, b⟩,
haveI :=
have sizeof a + sizeof l₂ <
sizeof a + sizeof (lists'.cons' b l₂),
by default_dec_tac,
mem.decidable a l₂,
refine decidable_of_iff' (a ~ ⟨_, b⟩ ∨ a ∈ l₂) _,
rw ← lists'.mem_cons, refl
end
using_well_founded {
rel_tac := λ _ _, `[exact ⟨_, measure_wf equiv.decidable_meas⟩],
dec_tac := `[assumption] }
end decidable
end lists
namespace lists'
theorem mem_equiv_left {l : lists' α tt} :
∀ {a a'}, a ~ a' → (a ∈ l ↔ a' ∈ l) :=
suffices ∀ {a a'}, a ~ a' → a ∈ l → a' ∈ l,
from λ a a' e, ⟨this e, this e.symm⟩,
λ a₁ a₂ e₁ ⟨a₃, m₃, e₂⟩, ⟨_, m₃, e₁.symm.trans e₂⟩
theorem mem_of_subset {a} {l₁ l₂ : lists' α tt}
(s : l₁ ⊆ l₂) : a ∈ l₁ → a ∈ l₂ | ⟨a', m, e⟩ :=
(mem_equiv_left e).2 (mem_of_subset' s m)
theorem subset.trans {l₁ l₂ l₃ : lists' α tt}
(h₁ : l₁ ⊆ l₂) (h₂ : l₂ ⊆ l₃) : l₁ ⊆ l₃ :=
subset_def.2 $ λ a₁ m₁, mem_of_subset h₂ $ mem_of_subset' h₁ m₁
end lists'
def finsets (α : Type*) := quotient (@lists.setoid α)
namespace finsets
instance : has_emptyc (finsets α) := ⟨⟦lists.of' lists'.nil⟧⟩
instance [decidable_eq α] : decidable_eq (finsets α) :=
by unfold finsets; apply_instance
end finsets
|
84923489d2750b050a99b2eecc1d078a35e947b8 | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/category_theory/essentially_small.lean | bf2ba4d685a00efe05eac6169da01f7b872b4535 | [
"Apache-2.0"
] | permissive | jjgarzella/mathlib | 96a345378c4e0bf26cf604aed84f90329e4896a2 | 395d8716c3ad03747059d482090e2bb97db612c8 | refs/heads/master | 1,686,480,124,379 | 1,625,163,323,000 | 1,625,163,323,000 | 281,190,421 | 2 | 0 | Apache-2.0 | 1,595,268,170,000 | 1,595,268,169,000 | null | UTF-8 | Lean | false | false | 7,165 | lean | /-
Copyright (c) 2021 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import logic.small
import category_theory.skeletal
/-!
# Essentially small categories.
A category given by `(C : Type u) [category.{v} C]` is `w`-essentially small
if there exists a `small_model C : Type w` equipped with `[small_category (small_model C)]`.
A category is `w`-locally small if every hom type is `w`-small.
The main theorem here is that a category is `w`-essentially small iff
the type `skeleton C` is `w`-small, and `C` is `w`-locally small.
-/
universes w v v' u u'
open category_theory
variables (C : Type u) [category.{v} C]
namespace category_theory
/-- A category is `essentially_small.{w}` if there exists
an equivalence to some `S : Type w` with `[small_category S]`. -/
class essentially_small (C : Type u) [category.{v} C] : Prop :=
(equiv_small_category : ∃ (S : Type w) [small_category S], by exactI nonempty (C ≌ S))
/-- Constructor for `essentially_small C` from an explicit small category witness. -/
lemma essentially_small.mk' {C : Type u} [category.{v} C] {S : Type w} [small_category S]
(e : C ≌ S) : essentially_small.{w} C :=
⟨⟨S, _, ⟨e⟩⟩⟩
/--
An arbitrarily chosen small model for an essentially small category.
-/
@[nolint has_inhabited_instance]
def small_model (C : Type u) [category.{v} C] [essentially_small.{w} C] : Type w :=
classical.some (@essentially_small.equiv_small_category C _ _)
noncomputable
instance small_category_small_model
(C : Type u) [category.{v} C] [essentially_small.{w} C] : small_category (small_model C) :=
classical.some (classical.some_spec (@essentially_small.equiv_small_category C _ _))
/--
The (noncomputable) categorical equivalence between
an essentially small category and its small model.
-/
noncomputable
def equiv_small_model (C : Type u) [category.{v} C] [essentially_small.{w} C] : C ≌ small_model C :=
nonempty.some (classical.some_spec (classical.some_spec
(@essentially_small.equiv_small_category C _ _)))
lemma essentially_small_congr {C : Type u} [category.{v} C] {D : Type u'} [category.{v'} D]
(e : C ≌ D) : essentially_small.{w} C ↔ essentially_small.{w} D :=
begin
fsplit,
{ rintro ⟨S, 𝒮, ⟨f⟩⟩,
resetI,
exact essentially_small.mk' (e.symm.trans f), },
{ rintro ⟨S, 𝒮, ⟨f⟩⟩,
resetI,
exact essentially_small.mk' (e.trans f), },
end
/--
A category is `w`-locally small if every hom set is `w`-small.
See `shrink_homs C` for a category instance where every hom set has been replaced by a small model.
-/
class locally_small (C : Type u) [category.{v} C] : Prop :=
(hom_small : ∀ X Y : C, small.{w} (X ⟶ Y) . tactic.apply_instance)
instance (C : Type u) [category.{v} C] [locally_small.{w} C] (X Y : C) :
small (X ⟶ Y) :=
locally_small.hom_small X Y
lemma locally_small_congr {C : Type u} [category.{v} C] {D : Type u'} [category.{v'} D]
(e : C ≌ D) : locally_small.{w} C ↔ locally_small.{w} D :=
begin
fsplit,
{ rintro ⟨L⟩,
fsplit,
intros X Y,
specialize L (e.inverse.obj X) (e.inverse.obj Y),
refine (small_congr _).mpr L,
exact equiv_of_fully_faithful e.inverse, },
{ rintro ⟨L⟩,
fsplit,
intros X Y,
specialize L (e.functor.obj X) (e.functor.obj Y),
refine (small_congr _).mpr L,
exact equiv_of_fully_faithful e.functor, },
end
@[priority 100]
instance locally_small_self (C : Type u) [category.{v} C] : locally_small.{v} C := {}
@[priority 100]
instance locally_small_of_essentially_small
(C : Type u) [category.{v} C] [essentially_small.{w} C] : locally_small.{w} C :=
(locally_small_congr (equiv_small_model C)).mpr (category_theory.locally_small_self _)
/--
We define a type alias `shrink_homs C` for `C`. When we have `locally_small.{w} C`,
we'll put a `category.{w}` instance on `shrink_homs C`.
-/
@[nolint has_inhabited_instance]
def shrink_homs (C : Type u) := C
namespace shrink_homs
section
variables {C' : Type*} -- a fresh variable with no category instance attached
/-- Help the typechecker by explicitly translating from `C` to `shrink_homs C`. -/
def to_shrink_homs {C' : Type*} (X : C') : shrink_homs C' := X
/-- Help the typechecker by explicitly translating from `shrink_homs C` to `C`. -/
def from_shrink_homs {C' : Type*} (X : shrink_homs C') : C' := X
@[simp] lemma to_from (X : C') : from_shrink_homs (to_shrink_homs X) = X := rfl
@[simp] lemma from_to (X : shrink_homs C') : to_shrink_homs (from_shrink_homs X) = X := rfl
end
variables (C) [locally_small.{w} C]
@[simps]
noncomputable
instance : category.{w} (shrink_homs C) :=
{ hom := λ X Y, shrink (from_shrink_homs X ⟶ from_shrink_homs Y),
id := λ X, equiv_shrink _ (𝟙 (from_shrink_homs X)),
comp := λ X Y Z f g,
equiv_shrink _ (((equiv_shrink _).symm f) ≫ ((equiv_shrink _).symm g)), }.
/-- Implementation of `shrink_homs.equivalence`. -/
@[simps]
noncomputable
def functor : C ⥤ shrink_homs C :=
{ obj := λ X, to_shrink_homs X,
map := λ X Y f, equiv_shrink (X ⟶ Y) f, }
/-- Implementation of `shrink_homs.equivalence`. -/
@[simps]
noncomputable
def inverse : shrink_homs C ⥤ C :=
{ obj := λ X, from_shrink_homs X,
map := λ X Y f, (equiv_shrink (from_shrink_homs X ⟶ from_shrink_homs Y)).symm f, }
/--
The categorical equivalence between `C` and `shrink_homs C`, when `C` is locally small.
-/
@[simps]
noncomputable
def equivalence : C ≌ shrink_homs C :=
equivalence.mk (functor C) (inverse C)
(nat_iso.of_components (λ X, iso.refl X) (by tidy))
(nat_iso.of_components (λ X, iso.refl X) (by tidy))
end shrink_homs
/--
A category is essentially small if and only if
the underlying type of its skeleton (i.e. the "set" of isomorphism classes) is small,
and it is locally small.
-/
theorem essentially_small_iff (C : Type u) [category.{v} C] :
essentially_small.{w} C ↔ small.{w} (skeleton C) ∧ locally_small.{w} C :=
begin
-- This theorem is the only bit of real work in this file.
fsplit,
{ intro h,
fsplit,
{ rcases h with ⟨S, 𝒮, ⟨e⟩⟩,
resetI,
refine ⟨⟨skeleton S, ⟨_⟩⟩⟩,
exact e.skeleton_equiv, },
{ resetI, apply_instance, }, },
{ rintro ⟨⟨S, ⟨e⟩⟩, L⟩,
resetI,
let e' := (shrink_homs.equivalence C).skeleton_equiv.symm,
refine ⟨⟨S, _, ⟨_⟩⟩⟩,
apply induced_category.category (e'.trans e).symm,
refine (shrink_homs.equivalence C).trans
((from_skeleton _).as_equivalence.symm.trans
((induced_functor (e'.trans e).symm).as_equivalence.symm)), },
end
/--
Any thin category is locally small.
-/
@[priority 100]
instance locally_small_of_thin {C : Type u} [category.{v} C] [∀ X Y : C, subsingleton (X ⟶ Y)] :
locally_small.{w} C := {}
/--
A thin category is essentially small if and only if the underlying type of its skeleton is small.
-/
theorem essentially_small_iff_of_thin
{C : Type u} [category.{v} C] [∀ X Y : C, subsingleton (X ⟶ Y)] :
essentially_small.{w} C ↔ small.{w} (skeleton C) :=
by simp [essentially_small_iff, category_theory.locally_small_of_thin]
end category_theory
|
6d6e520713b73c7497e59d9c171e5a6e183dc8e3 | 55c7fc2bf55d496ace18cd6f3376e12bb14c8cc5 | /src/ring_theory/adjoin_root.lean | 2d74442e8e871dabd21d239e379025d390e1a48b | [
"Apache-2.0"
] | permissive | dupuisf/mathlib | 62de4ec6544bf3b79086afd27b6529acfaf2c1bb | 8582b06b0a5d06c33ee07d0bdf7c646cae22cf36 | refs/heads/master | 1,669,494,854,016 | 1,595,692,409,000 | 1,595,692,409,000 | 272,046,630 | 0 | 0 | Apache-2.0 | 1,592,066,143,000 | 1,592,066,142,000 | null | UTF-8 | Lean | false | false | 4,933 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro, Chris Hughes
Adjoining roots of polynomials
-/
import data.polynomial.field_division
import ring_theory.adjoin
import ring_theory.principal_ideal_domain
/-!
# Adjoining roots of polynomials
This file defines the commutative ring `adjoin_root f`, the ring R[X]/(f) obtained from a
commutative ring `R` and a polynomial `f : R[X]`. If furthermore `R` is a field and `f` is
irreducible, the field structure on `adjoin_root f` is constructed.
## Main definitions and results
The main definitions are in the `adjoin_root` namespace.
* `mk f : polynomial R →+* adjoin_root f`, the natural ring homomorphism.
* `of f : R →+* adjoin_root f`, the natural ring homomorphism.
* `root f : adjoin_root f`, the image of X in R[X]/(f).
* `lift (i : R →+* S) (x : S) (h : f.eval₂ i x = 0) : (adjoin_root f) →+* S`, the ring
homomorphism from R[X]/(f) to S extending `i : R →+* S` and sending `X` to `x`.
-/
noncomputable theory
open_locale big_operators
universes u v w
variables {R : Type u} {S : Type v} {K : Type w}
open polynomial ideal
/-- Adjoin a root of a polynomial `f` to a commutative ring `R`. We define the new ring
as the quotient of `R` by the principal ideal of `f`. -/
def adjoin_root [comm_ring R] (f : polynomial R) : Type u :=
ideal.quotient (span {f} : ideal (polynomial R))
namespace adjoin_root
section comm_ring
variables [comm_ring R] (f : polynomial R)
instance : comm_ring (adjoin_root f) := ideal.quotient.comm_ring _
instance : inhabited (adjoin_root f) := ⟨0⟩
instance : decidable_eq (adjoin_root f) := classical.dec_eq _
/-- Ring homomorphism from `R[x]` to `adjoin_root f` sending `X` to the `root`. -/
def mk : polynomial R →+* adjoin_root f := ideal.quotient.mk _
@[elab_as_eliminator]
theorem induction_on {C : adjoin_root f → Prop} (x : adjoin_root f)
(ih : ∀ p : polynomial R, C (mk f p)) : C x :=
quotient.induction_on' x ih
/-- Embedding of the original ring `R` into `adjoin_root f`. -/
def of : R →+* adjoin_root f := (mk f).comp (ring_hom.of C)
instance : algebra R (adjoin_root f) := (of f).to_algebra
@[simp] lemma algebra_map_eq : algebra_map R (adjoin_root f) = of f := rfl
/-- The adjoined root. -/
def root : adjoin_root f := mk f X
variables {f}
instance adjoin_root.has_coe_t : has_coe_t R (adjoin_root f) := ⟨of f⟩
@[simp] lemma mk_self : mk f f = 0 :=
quotient.sound' (mem_span_singleton.2 $ by simp)
@[simp] lemma mk_C (x : R) : mk f (C x) = x := rfl
@[simp] lemma mk_X : mk f X = root f := rfl
@[simp] lemma aeval_eq (p : polynomial R) : aeval (root f) p = mk f p :=
polynomial.induction_on p (λ x, by { rw aeval_C, refl })
(λ p q ihp ihq, by rw [alg_hom.map_add, ring_hom.map_add, ihp, ihq])
(λ n x ih, by { rw [alg_hom.map_mul, aeval_C, alg_hom.map_pow, aeval_X,
ring_hom.map_mul, mk_C, ring_hom.map_pow, mk_X], refl })
theorem adjoin_root_eq_top : algebra.adjoin R ({root f} : set (adjoin_root f)) = ⊤ :=
algebra.eq_top_iff.2 $ λ x, induction_on f x $ λ p,
(algebra.adjoin_singleton_eq_range R (root f)).symm ▸ ⟨p, aeval_eq p⟩
@[simp] lemma eval₂_root (f : polynomial R) : f.eval₂ (of f) (root f) = 0 :=
by rw [← algebra_map_eq, ← aeval_def, aeval_eq, mk_self]
lemma is_root_root (f : polynomial R) : is_root (f.map (of f)) (root f) :=
by rw [is_root, eval_map, eval₂_root]
variables [comm_ring S]
/-- Lift a ring homomorphism `i : R →+* S` to `adjoin_root f →+* S`. -/
def lift (i : R →+* S) (x : S) (h : f.eval₂ i x = 0) : (adjoin_root f) →+* S :=
begin
apply ideal.quotient.lift _ (eval₂_ring_hom i x),
intros g H,
rcases mem_span_singleton.1 H with ⟨y, hy⟩,
rw [hy, ring_hom.map_mul, coe_eval₂_ring_hom, h, zero_mul]
end
variables {i : R →+* S} {a : S} {h : f.eval₂ i a = 0}
@[simp] lemma lift_mk {g : polynomial R} : lift i a h (mk f g) = g.eval₂ i a :=
ideal.quotient.lift_mk _ _ _
@[simp] lemma lift_root : lift i a h (root f) = a := by rw [root, lift_mk, eval₂_X]
@[simp] lemma lift_of {x : R} : lift i a h x = i x :=
by rw [← mk_C x, lift_mk, eval₂_C]
@[simp] lemma lift_comp_of : (lift i a h).comp (of f) = i :=
ring_hom.ext $ λ _, @lift_of _ _ _ _ _ _ _ h _
end comm_ring
variables [field K] {f : polynomial K} [irreducible f]
instance is_maximal_span : is_maximal (span {f} : ideal (polynomial K)) :=
principal_ideal_ring.is_maximal_of_irreducible ‹irreducible f›
noncomputable instance field : field (adjoin_root f) :=
ideal.quotient.field (span {f} : ideal (polynomial K))
lemma coe_injective : function.injective (coe : K → adjoin_root f) :=
(of f).injective
variable (f)
lemma mul_div_root_cancel :
((X - C (root f)) * (f.map (of f) / (X - C (root f))) : polynomial (adjoin_root f)) =
f.map (of f) :=
mul_div_eq_iff_is_root.2 $ is_root_root _
end adjoin_root
|
6438fcf786d61784aca3c18fc8130089a8ff8556 | a0e23cfdd129a671bf3154ee1a8a3a72bf4c7940 | /stage0/src/Lean/Meta/AppBuilder.lean | 71851fc57f6b3ba21ced69e119b493a3488e189e | [
"Apache-2.0"
] | permissive | WojciechKarpiel/lean4 | 7f89706b8e3c1f942b83a2c91a3a00b05da0e65b | f6e1314fa08293dea66a329e05b6c196a0189163 | refs/heads/master | 1,686,633,402,214 | 1,625,821,189,000 | 1,625,821,258,000 | 384,640,886 | 0 | 0 | Apache-2.0 | 1,625,903,617,000 | 1,625,903,026,000 | null | UTF-8 | Lean | false | false | 19,857 | lean | /-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
import Lean.Structure
import Lean.Util.Recognizers
import Lean.Meta.SynthInstance
import Lean.Meta.Check
namespace Lean.Meta
/-- Return `id e` -/
def mkId (e : Expr) : MetaM Expr := do
let type ← inferType e
let u ← getLevel type
return mkApp2 (mkConst ``id [u]) type e
/-- Return `idRhs e` -/
def mkIdRhs (e : Expr) : MetaM Expr := do
let type ← inferType e
let u ← getLevel type
return mkApp2 (mkConst ``idRhs [u]) type e
/--
Given `e` s.t. `inferType e` is definitionally equal to `expectedType`, return
term `@id expectedType e`. -/
def mkExpectedTypeHint (e : Expr) (expectedType : Expr) : MetaM Expr := do
let u ← getLevel expectedType
return mkApp2 (mkConst ``id [u]) expectedType e
def mkEq (a b : Expr) : MetaM Expr := do
let aType ← inferType a
let u ← getLevel aType
return mkApp3 (mkConst ``Eq [u]) aType a b
def mkHEq (a b : Expr) : MetaM Expr := do
let aType ← inferType a
let bType ← inferType b
let u ← getLevel aType
return mkApp4 (mkConst ``HEq [u]) aType a bType b
def mkEqRefl (a : Expr) : MetaM Expr := do
let aType ← inferType a
let u ← getLevel aType
return mkApp2 (mkConst ``Eq.refl [u]) aType a
def mkHEqRefl (a : Expr) : MetaM Expr := do
let aType ← inferType a
let u ← getLevel aType
return mkApp2 (mkConst ``HEq.refl [u]) aType a
def mkAbsurd (e : Expr) (hp hnp : Expr) : MetaM Expr := do
let p ← inferType hp
let u ← getLevel e
return mkApp4 (mkConst ``absurd [u]) p e hp hnp
def mkFalseElim (e : Expr) (h : Expr) : MetaM Expr := do
let u ← getLevel e
return mkApp2 (mkConst ``False.elim [u]) e h
private def infer (h : Expr) : MetaM Expr := do
let hType ← inferType h
whnfD hType
private def hasTypeMsg (e type : Expr) : MessageData :=
m!"{indentExpr e}\nhas type{indentExpr type}"
private def throwAppBuilderException {α} (op : Name) (msg : MessageData) : MetaM α :=
throwError "AppBuilder for '{op}', {msg}"
def mkEqSymm (h : Expr) : MetaM Expr := do
if h.isAppOf ``Eq.refl then
return h
else
let hType ← infer h
match hType.eq? with
| some (α, a, b) =>
let u ← getLevel α
return mkApp4 (mkConst ``Eq.symm [u]) α a b h
| none => throwAppBuilderException ``Eq.symm ("equality proof expected" ++ hasTypeMsg h hType)
def mkEqTrans (h₁ h₂ : Expr) : MetaM Expr := do
if h₁.isAppOf ``Eq.refl then
return h₂
else if h₂.isAppOf ``Eq.refl then
return h₁
else
let hType₁ ← infer h₁
let hType₂ ← infer h₂
match hType₁.eq?, hType₂.eq? with
| some (α, a, b), some (_, _, c) =>
let u ← getLevel α
return mkApp6 (mkConst ``Eq.trans [u]) α a b c h₁ h₂
| none, _ => throwAppBuilderException ``Eq.trans ("equality proof expected" ++ hasTypeMsg h₁ hType₁)
| _, none => throwAppBuilderException ``Eq.trans ("equality proof expected" ++ hasTypeMsg h₂ hType₂)
def mkHEqSymm (h : Expr) : MetaM Expr := do
if h.isAppOf ``HEq.refl then
return h
else
let hType ← infer h
match hType.heq? with
| some (α, a, β, b) =>
let u ← getLevel α
return mkApp5 (mkConst ``HEq.symm [u]) α β a b h
| none =>
throwAppBuilderException ``HEq.symm ("heterogeneous equality proof expected" ++ hasTypeMsg h hType)
def mkHEqTrans (h₁ h₂ : Expr) : MetaM Expr := do
if h₁.isAppOf ``HEq.refl then
return h₂
else if h₂.isAppOf ``HEq.refl then
return h₁
else
let hType₁ ← infer h₁
let hType₂ ← infer h₂
match hType₁.heq?, hType₂.heq? with
| some (α, a, β, b), some (_, _, γ, c) =>
let u ← getLevel α
return mkApp8 (mkConst ``HEq.trans [u]) α β γ a b c h₁ h₂
| none, _ => throwAppBuilderException ``HEq.trans ("heterogeneous equality proof expected" ++ hasTypeMsg h₁ hType₁)
| _, none => throwAppBuilderException ``HEq.trans ("heterogeneous equality proof expected" ++ hasTypeMsg h₂ hType₂)
def mkEqOfHEq (h : Expr) : MetaM Expr := do
let hType ← infer h
match hType.heq? with
| some (α, a, β, b) =>
unless (← isDefEq α β) do
throwAppBuilderException ``eqOfHEq m!"heterogeneous equality types are not definitionally equal{indentExpr α}\nis not definitionally equal to{indentExpr β}"
let u ← getLevel α
return mkApp4 (mkConst ``eqOfHEq [u]) α a b h
| _ =>
throwAppBuilderException ``HEq.trans m!"heterogeneous equality proof expected{indentExpr h}"
def mkCongrArg (f h : Expr) : MetaM Expr := do
if h.isAppOf ``Eq.refl then
mkEqRefl (mkApp f h.appArg!)
else
let hType ← infer h
let fType ← infer f
match fType.arrow?, hType.eq? with
| some (α, β), some (_, a, b) =>
let u ← getLevel α
let v ← getLevel β
return mkApp6 (mkConst ``congrArg [u, v]) α β a b f h
| none, _ => throwAppBuilderException ``congrArg ("non-dependent function expected" ++ hasTypeMsg f fType)
| _, none => throwAppBuilderException ``congrArg ("equality proof expected" ++ hasTypeMsg h hType)
def mkCongrFun (h a : Expr) : MetaM Expr := do
if h.isAppOf ``Eq.refl then
mkEqRefl (mkApp h.appArg! a)
else
let hType ← infer h
match hType.eq? with
| some (ρ, f, g) => do
let ρ ← whnfD ρ
match ρ with
| Expr.forallE n α β _ =>
let β' := Lean.mkLambda n BinderInfo.default α β
let u ← getLevel α
let v ← getLevel (mkApp β' a)
return mkApp6 (mkConst ``congrFun [u, v]) α β' f g h a
| _ => throwAppBuilderException ``congrFun ("equality proof between functions expected" ++ hasTypeMsg h hType)
| _ => throwAppBuilderException ``congrFun ("equality proof expected" ++ hasTypeMsg h hType)
def mkCongr (h₁ h₂ : Expr) : MetaM Expr := do
if h₁.isAppOf ``Eq.refl then
mkCongrArg h₁.appArg! h₂
else if h₂.isAppOf ``Eq.refl then
mkCongrFun h₁ h₂.appArg!
else
let hType₁ ← infer h₁
let hType₂ ← infer h₂
match hType₁.eq?, hType₂.eq? with
| some (ρ, f, g), some (α, a, b) =>
let ρ ← whnfD ρ
match ρ.arrow? with
| some (_, β) => do
let u ← getLevel α
let v ← getLevel β
return mkApp8 (mkConst ``congr [u, v]) α β f g a b h₁ h₂
| _ => throwAppBuilderException ``congr ("non-dependent function expected" ++ hasTypeMsg h₁ hType₁)
| none, _ => throwAppBuilderException ``congr ("equality proof expected" ++ hasTypeMsg h₁ hType₁)
| _, none => throwAppBuilderException ``congr ("equality proof expected" ++ hasTypeMsg h₂ hType₂)
private def mkAppMFinal (methodName : Name) (f : Expr) (args : Array Expr) (instMVars : Array MVarId) : MetaM Expr := do
instMVars.forM fun mvarId => do
let mvarDecl ← getMVarDecl mvarId
let mvarVal ← synthInstance mvarDecl.type
assignExprMVar mvarId mvarVal
let result ← instantiateMVars (mkAppN f args)
if (← hasAssignableMVar result) then throwAppBuilderException methodName ("result contains metavariables" ++ indentExpr result)
return result
private partial def mkAppMArgs (f : Expr) (fType : Expr) (xs : Array Expr) : MetaM Expr :=
let rec loop (type : Expr) (i : Nat) (j : Nat) (args : Array Expr) (instMVars : Array MVarId) : MetaM Expr := do
if i >= xs.size then
mkAppMFinal `mkAppM f args instMVars
else match type with
| Expr.forallE n d b c =>
let d := d.instantiateRevRange j args.size args
match c.binderInfo with
| BinderInfo.implicit =>
let mvar ← mkFreshExprMVar d MetavarKind.natural n
loop b i j (args.push mvar) instMVars
| BinderInfo.instImplicit =>
let mvar ← mkFreshExprMVar d MetavarKind.synthetic n
loop b i j (args.push mvar) (instMVars.push mvar.mvarId!)
| _ =>
let x := xs[i]
let xType ← inferType x
if (← isDefEq d xType) then
loop b (i+1) j (args.push x) instMVars
else
throwAppTypeMismatch (mkAppN f args) x
| type =>
let type := type.instantiateRevRange j args.size args
let type ← whnfD type
if type.isForall then
loop type i args.size args instMVars
else
throwAppBuilderException `mkAppM m!"too many explicit arguments provided to{indentExpr f}\narguments{indentD xs}"
loop fType 0 0 #[] #[]
private def mkFun (constName : Name) : MetaM (Expr × Expr) := do
let cinfo ← getConstInfo constName
let us ← cinfo.levelParams.mapM fun _ => mkFreshLevelMVar
let f := mkConst constName us
let fType := cinfo.instantiateTypeLevelParams us
return (f, fType)
/--
Return the application `constName xs`.
It tries to fill the implicit arguments before the last element in `xs`.
Remark:
``mkAppM `arbitrary #[α]`` returns `@arbitrary.{u} α` without synthesizing
the implicit argument occurring after `α`.
Given a `x : (([Decidable p] → Bool) × Nat`, ``mkAppM `Prod.fst #[x]`` returns `@Prod.fst ([Decidable p] → Bool) Nat x`
-/
def mkAppM (constName : Name) (xs : Array Expr) : MetaM Expr := do
traceCtx `Meta.appBuilder <| withNewMCtxDepth do
let (f, fType) ← mkFun constName
let r ← mkAppMArgs f fType xs
trace[Meta.appBuilder] "constName: {constName}, xs: {xs}, result: {r}"
return r
private partial def mkAppOptMAux (f : Expr) (xs : Array (Option Expr)) : Nat → Array Expr → Nat → Array MVarId → Expr → MetaM Expr
| i, args, j, instMVars, Expr.forallE n d b c => do
let d := d.instantiateRevRange j args.size args
if h : i < xs.size then
match xs.get ⟨i, h⟩ with
| none =>
match c.binderInfo with
| BinderInfo.instImplicit => do
let mvar ← mkFreshExprMVar d MetavarKind.synthetic n
mkAppOptMAux f xs (i+1) (args.push mvar) j (instMVars.push mvar.mvarId!) b
| _ => do
let mvar ← mkFreshExprMVar d MetavarKind.natural n
mkAppOptMAux f xs (i+1) (args.push mvar) j instMVars b
| some x =>
let xType ← inferType x
if (← isDefEq d xType) then
mkAppOptMAux f xs (i+1) (args.push x) j instMVars b
else
throwAppTypeMismatch (mkAppN f args) x
else
mkAppMFinal `mkAppOptM f args instMVars
| i, args, j, instMVars, type => do
let type := type.instantiateRevRange j args.size args
let type ← whnfD type
if type.isForall then
mkAppOptMAux f xs i args args.size instMVars type
else if i == xs.size then
mkAppMFinal `mkAppOptM f args instMVars
else do
let xs : Array Expr := xs.foldl (fun r x? => match x? with | none => r | some x => r.push x) #[]
throwAppBuilderException `mkAppOptM ("too many arguments provided to" ++ indentExpr f ++ Format.line ++ "arguments" ++ xs)
/--
Similar to `mkAppM`, but it allows us to specify which arguments are provided explicitly using `Option` type.
Example:
Given `Pure.pure {m : Type u → Type v} [Pure m] {α : Type u} (a : α) : m α`,
```
mkAppOptM `Pure.pure #[m, none, none, a]
```
returns a `Pure.pure` application if the instance `Pure m` can be synthesized, and the universe match.
Note that,
```
mkAppM `Pure.pure #[a]
```
fails because the only explicit argument `(a : α)` is not sufficient for inferring the remaining arguments,
we would need the expected type. -/
def mkAppOptM (constName : Name) (xs : Array (Option Expr)) : MetaM Expr := do
traceCtx `Meta.appBuilder <| withNewMCtxDepth do
let (f, fType) ← mkFun constName
mkAppOptMAux f xs 0 #[] 0 #[] fType
def mkEqNDRec (motive h1 h2 : Expr) : MetaM Expr := do
if h2.isAppOf ``Eq.refl then
return h1
else
let h2Type ← infer h2
match h2Type.eq? with
| none => throwAppBuilderException ``Eq.ndrec ("equality proof expected" ++ hasTypeMsg h2 h2Type)
| some (α, a, b) =>
let u2 ← getLevel α
let motiveType ← infer motive
match motiveType with
| Expr.forallE _ _ (Expr.sort u1 _) _ =>
return mkAppN (mkConst ``Eq.ndrec [u1, u2]) #[α, a, motive, h1, b, h2]
| _ => throwAppBuilderException ``Eq.ndrec ("invalid motive" ++ indentExpr motive)
def mkEqRec (motive h1 h2 : Expr) : MetaM Expr := do
if h2.isAppOf ``Eq.refl then
return h1
else
let h2Type ← infer h2
match h2Type.eq? with
| none => throwAppBuilderException ``Eq.rec ("equality proof expected" ++ indentExpr h2)
| some (α, a, b) =>
let u2 ← getLevel α
let motiveType ← infer motive
match motiveType with
| Expr.forallE _ _ (Expr.forallE _ _ (Expr.sort u1 _) _) _ =>
return mkAppN (mkConst ``Eq.rec [u1, u2]) #[α, a, motive, h1, b, h2]
| _ =>
throwAppBuilderException ``Eq.rec ("invalid motive" ++ indentExpr motive)
def mkEqMP (eqProof pr : Expr) : MetaM Expr :=
mkAppM ``Eq.mp #[eqProof, pr]
def mkEqMPR (eqProof pr : Expr) : MetaM Expr :=
mkAppM ``Eq.mpr #[eqProof, pr]
def mkNoConfusion (target : Expr) (h : Expr) : MetaM Expr := do
let type ← inferType h
let type ← whnf type
match type.eq? with
| none => throwAppBuilderException `noConfusion ("equality expected" ++ hasTypeMsg h type)
| some (α, a, b) =>
let α ← whnf α
matchConstInduct α.getAppFn (fun _ => throwAppBuilderException `noConfusion ("inductive type expected" ++ indentExpr α)) fun v us => do
let u ← getLevel target
return mkAppN (mkConst (Name.mkStr v.name "noConfusion") (u :: us)) (α.getAppArgs ++ #[target, a, b, h])
def mkPure (monad : Expr) (e : Expr) : MetaM Expr :=
mkAppOptM ``Pure.pure #[monad, none, none, e]
/--
`mkProjection s fieldName` return an expression for accessing field `fieldName` of the structure `s`.
Remark: `fieldName` may be a subfield of `s`. -/
partial def mkProjection : Expr → Name → MetaM Expr
| s, fieldName => do
let type ← inferType s
let type ← whnf type
match type.getAppFn with
| Expr.const structName us _ =>
let env ← getEnv
unless isStructureLike env structName do
throwAppBuilderException `mkProjection ("structure expected" ++ hasTypeMsg s type)
match getProjFnForField? env structName fieldName with
| some projFn =>
let params := type.getAppArgs
return mkApp (mkAppN (mkConst projFn us) params) s
| none =>
let fields := getStructureFields env structName
let r? ← fields.findSomeM? fun fieldName' => do
match isSubobjectField? env structName fieldName' with
| none => pure none
| some _ =>
let parent ← mkProjection s fieldName'
(do let r ← mkProjection parent fieldName; return some r)
<|>
pure none
match r? with
| some r => pure r
| none => throwAppBuilderException `mkProjectionn ("invalid field name '" ++ toString fieldName ++ "' for" ++ hasTypeMsg s type)
| _ => throwAppBuilderException `mkProjectionn ("structure expected" ++ hasTypeMsg s type)
private def mkListLitAux (nil : Expr) (cons : Expr) : List Expr → Expr
| [] => nil
| x::xs => mkApp (mkApp cons x) (mkListLitAux nil cons xs)
def mkListLit (type : Expr) (xs : List Expr) : MetaM Expr := do
let u ← getDecLevel type
let nil := mkApp (mkConst ``List.nil [u]) type
match xs with
| [] => return nil
| _ =>
let cons := mkApp (mkConst ``List.cons [u]) type
return mkListLitAux nil cons xs
def mkArrayLit (type : Expr) (xs : List Expr) : MetaM Expr := do
let u ← getDecLevel type
let listLit ← mkListLit type xs
return mkApp (mkApp (mkConst ``List.toArray [u]) type) listLit
def mkSorry (type : Expr) (synthetic : Bool) : MetaM Expr := do
let u ← getLevel type
return mkApp2 (mkConst ``sorryAx [u]) type (toExpr synthetic)
/-- Return `Decidable.decide p` -/
def mkDecide (p : Expr) : MetaM Expr :=
mkAppOptM ``Decidable.decide #[p, none]
/-- Return a proof for `p : Prop` using `decide p` -/
def mkDecideProof (p : Expr) : MetaM Expr := do
let decP ← mkDecide p
let decEqTrue ← mkEq decP (mkConst ``Bool.true)
let h ← mkEqRefl (mkConst ``Bool.true)
let h ← mkExpectedTypeHint h decEqTrue
mkAppM ``ofDecideEqTrue #[h]
/-- Return `a < b` -/
def mkLt (a b : Expr) : MetaM Expr :=
mkAppM ``LT.lt #[a, b]
/-- Return `a <= b` -/
def mkLe (a b : Expr) : MetaM Expr :=
mkAppM ``LE.le #[a, b]
/-- Return `arbitrary α` -/
def mkArbitrary (α : Expr) : MetaM Expr :=
mkAppOptM ``arbitrary #[α, none]
/-- Return `sorryAx type` -/
def mkSyntheticSorry (type : Expr) : MetaM Expr :=
return mkApp2 (mkConst ``sorryAx [← getLevel type]) type (mkConst ``Bool.true)
/-- Return `funext h` -/
def mkFunExt (h : Expr) : MetaM Expr :=
mkAppM ``funext #[h]
/-- Return `propext h` -/
def mkPropExt (h : Expr) : MetaM Expr :=
mkAppM ``propext #[h]
/-- Return `ofEqTrue h` -/
def mkOfEqTrue (h : Expr) : MetaM Expr :=
mkAppM ``ofEqTrue #[h]
/-- Return `eqTrue h` -/
def mkEqTrue (h : Expr) : MetaM Expr :=
mkAppM ``eqTrue #[h]
/--
Return `eqFalse h`
`h` must have type definitionally equal to `¬ p` in the current
reducibility setting. -/
def mkEqFalse (h : Expr) : MetaM Expr :=
mkAppM ``eqFalse #[h]
/--
Return `eqFalse' h`
`h` must have type definitionally equal to `p → False` in the current
reducibility setting. -/
def mkEqFalse' (h : Expr) : MetaM Expr :=
mkAppM ``eqFalse' #[h]
def mkImpCongr (h₁ h₂ : Expr) : MetaM Expr :=
mkAppM ``impCongr #[h₁, h₂]
def mkImpCongrCtx (h₁ h₂ : Expr) : MetaM Expr :=
mkAppM ``impCongrCtx #[h₁, h₂]
def mkForallCongr (h : Expr) : MetaM Expr :=
mkAppM ``forallCongr #[h]
/-- Return instance for `[Monad m]` if there is one -/
def isMonad? (m : Expr) : MetaM (Option Expr) :=
try
let monadType ← mkAppM `Monad #[m]
let result ← trySynthInstance monadType
match result with
| LOption.some inst => pure inst
| _ => pure none
catch _ =>
pure none
/-- Return `(n : type)`, a numeric literal of type `type`. The method fails if we don't have an instance `OfNat type n` -/
def mkNumeral (type : Expr) (n : Nat) : MetaM Expr := do
let u ← getDecLevel type
let inst ← synthInstance (mkApp2 (mkConst ``OfNat [u]) type (mkNatLit n))
return mkApp3 (mkConst ``OfNat.ofNat [u]) type (mkNatLit n) inst
/--
Return `a op b`, where `op` has name `opName` and is implemented using the typeclass `className`.
This method assumes `a` and `b` have the same type, and typeclass `className` is heterogeneous.
Examples of supported clases: `HAdd`, `HSub`, `HMul`.
We use heterogeneous operators to ensure we have a uniform representation.
-/
private def mkBinaryOp (className : Name) (opName : Name) (a b : Expr) : MetaM Expr := do
let aType ← inferType a
let u ← getDecLevel aType
let inst ← synthInstance (mkApp3 (mkConst className [u, u, u]) aType aType aType)
return mkApp6 (mkConst opName [u, u, u]) aType aType aType inst a b
/-- Return `a + b` using a heterogeneous `+`. This method assumes `a` and `b` have the same type. -/
def mkAdd (a b : Expr) : MetaM Expr := mkBinaryOp ``HAdd ``HAdd.hAdd a b
/-- Return `a - b` using a heterogeneous `-`. This method assumes `a` and `b` have the same type. -/
def mkSub (a b : Expr) : MetaM Expr := mkBinaryOp ``HSub ``HSub.hSub a b
/-- Return `a * b` using a heterogeneous `*`. This method assumes `a` and `b` have the same type. -/
def mkMul (a b : Expr) : MetaM Expr := mkBinaryOp ``HMul ``HMul.hMul a b
builtin_initialize registerTraceClass `Meta.appBuilder
end Lean.Meta
|
82f9a543184931b9d584549557a123fdc1f3be9d | 2c096fdfecf64e46ea7bc6ce5521f142b5926864 | /doc/examples/widgets.lean | c2eaa8c2f3a2df284fdb35567c377b453da964c6 | [
"Apache-2.0",
"LLVM-exception",
"NCSA",
"LGPL-3.0-only",
"LicenseRef-scancode-inner-net-2.0",
"BSD-3-Clause",
"LGPL-2.0-or-later",
"Spencer-94",
"LGPL-2.1-or-later",
"HPND",
"LicenseRef-scancode-pcre",
"ISC",
"LGPL-2.1-only",
"LicenseRef-scancode-other-permissive",
"SunPro",
"CMU-Mach"... | permissive | Kha/lean4 | 1005785d2c8797ae266a303968848e5f6ce2fe87 | b99e11346948023cd6c29d248cd8f3e3fb3474cf | refs/heads/master | 1,693,355,498,027 | 1,669,080,461,000 | 1,669,113,138,000 | 184,748,176 | 0 | 0 | Apache-2.0 | 1,665,995,520,000 | 1,556,884,930,000 | Lean | UTF-8 | Lean | false | false | 9,706 | lean | import Lean
open Lean Widget
/-!
# The user-widgets system
Proving and programming are inherently interactive tasks. Lots of mathematical objects and data
structures are visual in nature. *User widgets* let you associate custom interactive UIs with
sections of a Lean document. User widgets are rendered in the Lean infoview.
## Trying it out
To try it out, simply type in the following code and place your cursor over the `#widget` command.
-/
@[widget]
def helloWidget : UserWidgetDefinition where
name := "Hello"
javascript := "
import * as React from 'react';
export default function(props) {
const name = props.name || 'world'
return React.createElement('p', {}, name + '!')
}"
#widget helloWidget .null
/-!
If you want to dive into a full sample right away, check out
[`RubiksCube`](https://github.com/leanprover/lean4-samples/blob/main/RubiksCube/).
Below, we'll explain the system piece by piece.
⚠️ WARNING: All of the user widget APIs are **unstable** and subject to breaking changes.
## Widget sources and instances
A *widget source* is a valid JavaScript [ESModule](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules)
which exports a [React component](https://reactjs.org/docs/components-and-props.html). To access
React, the module must use `import * as React from 'react'`. Our first example of a widget source
is of course the value of `helloWidget.javascript`.
We can register a widget source with the `@[widget]` attribute, giving it a friendlier name
in the `name` field. This is bundled together in a `UserWidgetDefinition`.
A *widget instance* is then the identifier of a `UserWidgetDefinition` (so `` `helloWidget ``,
not `"Hello"`) associated with a range of positions in the Lean source code. Widget instances
are stored in the *infotree* in the same manner as other information about the source file
such as the type of every expression. In our example, the `#widget` command stores a widget instance
with the entire line as its range. We can think of a widget instance as an instruction for the
infoview: "when the user places their cursor here, please render the following widget".
Every widget instance also contains a `props : Json` value. This value is passed as an argument
to the React component. In our first invocation of `#widget`, we set it to `.null`. Try out what
happens when you type in:
-/
#widget helloWidget (Json.mkObj [("name", "<your name here>")])
/-!
💡 NOTE: The RPC system presented below does not depend on JavaScript. However the primary use case
is the web-based infoview in VSCode.
## Querying the Lean server
Besides enabling us to create cool client-side visualizations, user widgets come with the ability
to communicate with the Lean server. Thanks to this, they have the same metaprogramming capabilities
as custom elaborators or the tactic framework. To see this in action, let's implement a `#check`
command as a web input form. This example assumes some familiarity with React.
The first thing we'll need is to create an *RPC method*. Meaning "Remote Procedure Call", this
is basically a Lean function callable from widget code (possibly remotely over the internet).
Our method will take in the `name : Name` of a constant in the environment and return its type.
By convention, we represent the input data as a `structure`. Since it will be sent over from JavaScript,
we need `FromJson` and `ToJson`. We'll see below why the position field is needed.
-/
structure GetTypeParams where
/-- Name of a constant to get the type of. -/
name : Name
/-- Position of our widget instance in the Lean file. -/
pos : Lsp.Position
deriving FromJson, ToJson
/-!
After its arguments, we define the `getType` method. Every RPC method executes in the `RequestM`
monad and must return a `RequestTask α` where `α` is its "actual" return type. The `Task` is so
that requests can be handled concurrently. A first guess for `α` might be `Expr`. However,
expressions in general can be large objects which depend on an `Environment` and `LocalContext`.
Thus we cannot directly serialize an `Expr` and send it to the widget. Instead, there are two
options:
- One is to send a *reference* which points to an object residing on the server. From JavaScript's
point of view, references are entirely opaque, but they can be sent back to other RPC methods for
further processing.
- Two is to pretty-print the expression and send its textual representation called `CodeWithInfos`.
This representation contains extra data which the infoview uses for interactivity. We take this
strategy here.
RPC methods execute in the context of a file, but not any particular `Environment` so they don't
know about the available `def`initions and `theorem`s. Thus, we need to pass in a position at which
we want to use the local `Environment`. This is why we store it in `GetTypeParams`. The `withWaitFindSnapAtPos`
method launches a concurrent computation whose job is to find such an `Environment` and a bit
more information for us, in the form of a `snap : Snapshot`. With this in hand, we can call
`MetaM` procedures to find out the type of `name` and pretty-print it.
-/
open Server RequestM in
@[server_rpc_method]
def getType (params : GetTypeParams) : RequestM (RequestTask CodeWithInfos) :=
withWaitFindSnapAtPos params.pos fun snap => do
runTermElabM snap do
let name ← resolveGlobalConstNoOverloadCore params.name
let some c ← Meta.getConst? name
| throwThe RequestError ⟨.invalidParams, s!"no constant named '{name}'"⟩
Widget.ppExprTagged c.type
/-!
## Using infoview components
Now that we have all we need on the server side, let's write the widget source. By importing
`@leanprover/infoview`, widgets can render UI components used to implement the infoview itself.
For example, the `<InteractiveCode>` component displays expressions with `term : type` tooltips
as seen in the goal view. We will use it to implement our custom `#check` display.
⚠️ WARNING: Like the other widget APIs, the infoview JS API is **unstable** and subject to breaking changes.
The code below demonstrates useful parts of the API. To make RPC method calls, we use the `RpcContext`.
The `useAsync` helper packs the results of a call into a `status` enum, the returned `val`ue in case
the call was successful, and otherwise an `err`or. Based on the `status` we either display
an `InteractiveCode`, or `mapRpcError` the error in order to turn it into a readable message.
-/
@[widget]
def checkWidget : UserWidgetDefinition where
name := "#check as a service"
javascript := "
import * as React from 'react';
const e = React.createElement;
import { RpcContext, InteractiveCode } from '@leanprover/infoview';
export default function(props) {
const rs = React.useContext(RpcContext)
const [name, setName] = React.useState('getType')
const [value, setValue] = React.useState(undefined)
function run() {
rs.call('getType', { name, pos: props.pos }).then(setValue)
}
React.useEffect(() => run(), [name])
const type = value && e(InteractiveCode, {fmt: value})
const onChange = (event) => { setName(event.target.value) }
return e('div', null, e('input', { value: name, onChange }), ' : ', type)
}
"
/-!
Finally we can try out the widget.
-/
#widget checkWidget .null
/-!
## Building widget sources
While typing JavaScript inline is fine for a simple example, for real developments we want to use
packages from NPM, a proper build system, and JSX. Thus, most actual widget sources are built with
Lake and NPM. They consist of multiple files and may import libraries which don't work as ESModules
by default. On the other hand a widget source must be a single, self-contained ESModule in the form
of a string. Readers familiar with web development may already have guessed that to obtain such a
string, we need a *bundler*. Two popular choices are [`rollup.js`](https://rollupjs.org/guide/en/)
and [`esbuild`](https://esbuild.github.io/). If we go with `rollup.js`, to make a widget work with
the infoview we need to:
- Set [`output.format`](https://rollupjs.org/guide/en/#outputformat) to `'es'`.
- [Externalize](https://rollupjs.org/guide/en/#external) `react`, `react-dom`, `@leanprover/infoview`.
These libraries are already loaded by the infoview so they should not be bundled.
In the RubiksCube sample, we provide a working `rollup.js` build configuration in
[rollup.config.js](https://github.com/leanprover/lean4-samples/blob/main/RubiksCube/widget/rollup.config.js).
## Inserting text
We can also instruct the editor to insert text, copy text to the clipboard, or
reveal a certain location in the document.
To do this, use the `React.useContext(EditorContext)` React context.
This will return an `EditorConnection` whose `api` field contains a number of methods to
interact with the text editor.
You can see the full API for this [here](https://github.com/leanprover/vscode-lean4/blob/1edd92230c7630627f18dbe76cd139903a4cbcee/lean4-infoview-api/src/infoviewApi.ts#L52)
-/
@[widget]
def insertTextWidget : UserWidgetDefinition where
name := "textInserter"
javascript := "
import * as React from 'react';
const e = React.createElement;
import { EditorContext } from '@leanprover/infoview';
export default function(props) {
const editorConnection = React.useContext(EditorContext)
function onClick() {
editorConnection.api.insertText('-- hello!!!', 'above')
}
return e('div', null, e('button', { value: name, onClick }, 'insert'))
}
"
/-! Finally, we can try this out: -/
#widget insertTextWidget .null
|
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Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Johannes Hölzl, Mario Carneiro
Cardinal arithmetic.
Cardinals are represented as quotient over equinumerous types.
-/
import data.set.finite data.quot logic.function set_theory.schroeder_bernstein
open function lattice set
local attribute [instance] classical.prop_decidable
universes u v w x
instance cardinal.is_equivalent : setoid (Type u) :=
{ r := λα β, nonempty (α ≃ β),
iseqv := ⟨λα,
⟨equiv.refl α⟩,
λα β ⟨e⟩, ⟨e.symm⟩,
λα β γ ⟨e₁⟩ ⟨e₂⟩, ⟨e₁.trans e₂⟩⟩ }
/-- `cardinal.{u}` is the type of cardinal numbers in `Type u`,
defined as the quotient of `Type u` by existence of an equivalence
(a bijection with explicit inverse). -/
def cardinal : Type (u + 1) := quotient cardinal.is_equivalent
namespace cardinal
/-- The cardinal of a type -/
def mk : Type u → cardinal := quotient.mk
@[simp] theorem mk_def (α : Type u) : @eq cardinal ⟦α⟧ (mk α) := rfl
@[simp] theorem mk_out (c : cardinal) : mk (c.out) = c := quotient.out_eq _
instance : has_le cardinal.{u} :=
⟨λq₁ q₂, quotient.lift_on₂ q₁ q₂ (λα β, nonempty $ α ↪ β) $
assume α β γ δ ⟨e₁⟩ ⟨e₂⟩,
propext ⟨assume ⟨e⟩, ⟨e.congr e₁ e₂⟩, assume ⟨e⟩, ⟨e.congr e₁.symm e₂.symm⟩⟩⟩
theorem mk_le_of_injective {α β : Type u} {f : α → β} (hf : injective f) : mk α ≤ mk β :=
⟨⟨f, hf⟩⟩
theorem mk_le_of_surjective {α β : Type u} {f : α → β} (hf : surjective f) : mk β ≤ mk α :=
⟨embedding.of_surjective hf⟩
theorem le_mk_iff_exists_set {c : cardinal} {α : Type u} :
c ≤ mk α ↔ ∃ p : set α, mk p = c :=
⟨quotient.induction_on c $ λ β ⟨⟨f, hf⟩⟩,
⟨set.range f, eq.symm $ quot.sound ⟨equiv.set.range f hf⟩⟩,
λ ⟨p, e⟩, e ▸ ⟨⟨subtype.val, λ a b, subtype.eq⟩⟩⟩
instance : linear_order cardinal.{u} :=
{ le := (≤),
le_refl := by rintros ⟨α⟩; exact ⟨embedding.refl _⟩,
le_trans := by rintros ⟨α⟩ ⟨β⟩ ⟨γ⟩ ⟨e₁⟩ ⟨e₂⟩; exact ⟨e₁.trans e₂⟩,
le_antisymm := by rintros ⟨α⟩ ⟨β⟩ ⟨e₁⟩ ⟨e₂⟩; exact quotient.sound (e₁.antisymm e₂),
le_total := by rintros ⟨α⟩ ⟨β⟩; exact embedding.total }
noncomputable instance : decidable_linear_order cardinal.{u} := classical.DLO _
noncomputable instance : distrib_lattice cardinal.{u} := by apply_instance
instance : has_zero cardinal.{u} := ⟨⟦pempty⟧⟩
instance : inhabited cardinal.{u} := ⟨0⟩
theorem ne_zero_iff_nonempty {α : Type u} : mk α ≠ 0 ↔ nonempty α :=
not_iff_comm.1
⟨λ h, quotient.sound ⟨(equiv.empty_of_not_nonempty h).trans equiv.empty_equiv_pempty⟩,
λ e, let ⟨h⟩ := quotient.exact e in λ ⟨a⟩, (h a).elim⟩
instance : has_one cardinal.{u} := ⟨⟦punit⟧⟩
instance : zero_ne_one_class cardinal.{u} :=
{ zero := 0, one := 1, zero_ne_one :=
ne.symm $ ne_zero_iff_nonempty.2 ⟨punit.star⟩ }
theorem le_one_iff_subsingleton {α : Type u} : mk α ≤ 1 ↔ subsingleton α :=
⟨λ ⟨f⟩, ⟨λ a b, f.inj (subsingleton.elim _ _)⟩,
λ ⟨h⟩, ⟨⟨λ a, punit.star, λ a b _, h _ _⟩⟩⟩
instance : has_add cardinal.{u} :=
⟨λq₁ q₂, quotient.lift_on₂ q₁ q₂ (λα β, mk (α ⊕ β)) $ assume α β γ δ ⟨e₁⟩ ⟨e₂⟩,
quotient.sound ⟨equiv.sum_congr e₁ e₂⟩⟩
@[simp] theorem add_def (α β) : mk α + mk β = mk (α ⊕ β) := rfl
instance : has_mul cardinal.{u} :=
⟨λq₁ q₂, quotient.lift_on₂ q₁ q₂ (λα β, mk (α × β)) $ assume α β γ δ ⟨e₁⟩ ⟨e₂⟩,
quotient.sound ⟨equiv.prod_congr e₁ e₂⟩⟩
@[simp] theorem mul_def (α β) : mk α * mk β = mk (α × β) := rfl
private theorem add_comm (a b : cardinal.{u}) : a + b = b + a :=
quotient.induction_on₂ a b $ assume α β, quotient.sound ⟨equiv.sum_comm α β⟩
private theorem mul_comm (a b : cardinal.{u}) : a * b = b * a :=
quotient.induction_on₂ a b $ assume α β, quotient.sound ⟨equiv.prod_comm α β⟩
private theorem zero_add (a : cardinal.{u}) : 0 + a = a :=
quotient.induction_on a $ assume α, quotient.sound ⟨equiv.pempty_sum α⟩
private theorem zero_mul (a : cardinal.{u}) : 0 * a = 0 :=
quotient.induction_on a $ assume α, quotient.sound ⟨equiv.pempty_prod α⟩
private theorem one_mul (a : cardinal.{u}) : 1 * a = a :=
quotient.induction_on a $ assume α, quotient.sound ⟨equiv.punit_prod α⟩
private theorem left_distrib (a b c : cardinal.{u}) : a * (b + c) = a * b + a * c :=
quotient.induction_on₃ a b c $ assume α β γ, quotient.sound ⟨equiv.prod_sum_distrib α β γ⟩
instance : comm_semiring cardinal.{u} :=
{ zero := 0,
one := 1,
add := (+),
mul := (*),
zero_add := zero_add,
add_zero := assume a, by rw [add_comm a 0, zero_add a],
add_assoc := λa b c, quotient.induction_on₃ a b c $ assume α β γ,
quotient.sound ⟨equiv.sum_assoc α β γ⟩,
add_comm := add_comm,
zero_mul := zero_mul,
mul_zero := assume a, by rw [mul_comm a 0, zero_mul a],
one_mul := one_mul,
mul_one := assume a, by rw [mul_comm a 1, one_mul a],
mul_assoc := λa b c, quotient.induction_on₃ a b c $ assume α β γ,
quotient.sound ⟨equiv.prod_assoc α β γ⟩,
mul_comm := mul_comm,
left_distrib := left_distrib,
right_distrib := assume a b c,
by rw [mul_comm (a + b) c, left_distrib c a b, mul_comm c a, mul_comm c b] }
/-- The cardinal exponential. `mk α ^ mk β` is the cardinal of `β → α`. -/
protected def power (a b : cardinal.{u}) : cardinal.{u} :=
quotient.lift_on₂ a b (λα β, mk (β → α)) $ assume α₁ α₂ β₁ β₂ ⟨e₁⟩ ⟨e₂⟩,
quotient.sound ⟨equiv.arrow_congr e₂ e₁⟩
instance : has_pow cardinal cardinal := ⟨cardinal.power⟩
local infixr ^ := @has_pow.pow cardinal cardinal cardinal.has_pow
@[simp] theorem power_def (α β) : mk α ^ mk β = mk (β → α) := rfl
@[simp] theorem power_zero {a : cardinal} : a ^ 0 = 1 :=
quotient.induction_on a $ assume α, quotient.sound
⟨equiv.pempty_arrow_equiv_punit α⟩
@[simp] theorem power_one {a : cardinal} : a ^ 1 = a :=
quotient.induction_on a $ assume α, quotient.sound
⟨equiv.punit_arrow_equiv α⟩
@[simp] theorem one_power {a : cardinal} : 1 ^ a = 1 :=
quotient.induction_on a $ assume α, quotient.sound
⟨equiv.arrow_punit_equiv_punit α⟩
@[simp] theorem prop_eq_two : mk (ulift Prop) = 2 :=
quot.sound ⟨equiv.ulift.trans $ equiv.Prop_equiv_bool.trans equiv.bool_equiv_punit_sum_punit⟩
@[simp] theorem zero_power {a : cardinal} : a ≠ 0 → 0 ^ a = 0 :=
quotient.induction_on a $ assume α heq,
nonempty.rec_on (ne_zero_iff_nonempty.1 heq) $ assume a,
quotient.sound ⟨equiv.equiv_pempty $ assume f, pempty.rec (λ _, false) (f a)⟩
theorem power_ne_zero {a : cardinal} (b) : a ≠ 0 → a ^ b ≠ 0 :=
quotient.induction_on₂ a b $ λ α β h,
let ⟨a⟩ := ne_zero_iff_nonempty.1 h in
ne_zero_iff_nonempty.2 ⟨λ _, a⟩
theorem mul_power {a b c : cardinal} : (a * b) ^ c = a ^ c * b ^ c :=
quotient.induction_on₃ a b c $ assume α β γ,
quotient.sound ⟨equiv.arrow_prod_equiv_prod_arrow α β γ⟩
theorem power_add {a b c : cardinal} : a ^ (b + c) = a ^ b * a ^ c :=
quotient.induction_on₃ a b c $ assume α β γ,
quotient.sound ⟨equiv.sum_arrow_equiv_prod_arrow β γ α⟩
theorem power_mul {a b c : cardinal} : (a ^ b) ^ c = a ^ (b * c) :=
by rw [_root_.mul_comm b c];
from (quotient.induction_on₃ a b c $ assume α β γ,
quotient.sound ⟨equiv.arrow_arrow_equiv_prod_arrow γ β α⟩)
section order_properties
open sum
theorem zero_le : ∀(a : cardinal), 0 ≤ a :=
by rintro ⟨α⟩; exact ⟨embedding.of_not_nonempty $ λ ⟨a⟩, a.elim⟩
theorem le_zero (a : cardinal) : a ≤ 0 ↔ a = 0 :=
by simp [le_antisymm_iff, zero_le]
theorem pos_iff_ne_zero {o : cardinal} : 0 < o ↔ o ≠ 0 :=
by simp [lt_iff_le_and_ne, eq_comm, zero_le]
theorem zero_lt_one : (0 : cardinal) < 1 :=
lt_of_le_of_ne (zero_le _) zero_ne_one
theorem add_le_add : ∀{a b c d : cardinal}, a ≤ b → c ≤ d → a + c ≤ b + d :=
by rintros ⟨α⟩ ⟨β⟩ ⟨γ⟩ ⟨δ⟩ ⟨e₁⟩ ⟨e₂⟩; exact ⟨embedding.sum_congr e₁ e₂⟩
theorem add_le_add_left (a) {b c : cardinal} : b ≤ c → a + b ≤ a + c :=
add_le_add (le_refl _)
theorem add_le_add_right {a b : cardinal} (c) (h : a ≤ b) : a + c ≤ b + c :=
add_le_add h (le_refl _)
theorem le_add_right (a b : cardinal) : a ≤ a + b :=
by simpa using add_le_add_left a (zero_le b)
theorem le_add_left (a b : cardinal) : a ≤ b + a :=
by simpa using add_le_add_right a (zero_le b)
theorem mul_le_mul : ∀{a b c d : cardinal}, a ≤ b → c ≤ d → a * c ≤ b * d :=
by rintros ⟨α⟩ ⟨β⟩ ⟨γ⟩ ⟨δ⟩ ⟨e₁⟩ ⟨e₂⟩; exact ⟨embedding.prod_congr e₁ e₂⟩
theorem mul_le_mul_left (a) {b c : cardinal} : b ≤ c → a * b ≤ a * c :=
mul_le_mul (le_refl _)
theorem mul_le_mul_right {a b : cardinal} (c) (h : a ≤ b) : a * c ≤ b * c :=
mul_le_mul h (le_refl _)
theorem power_le_power_left : ∀{a b c : cardinal}, a ≠ 0 → b ≤ c → a ^ b ≤ a ^ c :=
by rintros ⟨α⟩ ⟨β⟩ ⟨γ⟩ hα ⟨e⟩; exact
let ⟨a⟩ := ne_zero_iff_nonempty.1 hα in
⟨@embedding.arrow_congr_right _ _ _ ⟨a⟩ e⟩
theorem power_le_power_right {a b c : cardinal} : a ≤ b → a ^ c ≤ b ^ c :=
quotient.induction_on₃ a b c $ assume α β γ ⟨e⟩, ⟨embedding.arrow_congr_left e⟩
theorem le_iff_exists_add {a b : cardinal} : a ≤ b ↔ ∃ c, b = a + c :=
⟨quotient.induction_on₂ a b $ λ α β ⟨⟨f, hf⟩⟩,
have (α ⊕ ↥-range f) ≃ β, from
(equiv.sum_congr (equiv.set.range f hf) (equiv.refl _)).trans $
(equiv.set.sum_compl (range f)),
⟨⟦(-range f : set β)⟧, quotient.sound ⟨this.symm⟩⟩,
λ ⟨c, e⟩, add_zero a ▸ e.symm ▸ add_le_add_left _ (zero_le _)⟩
end order_properties
instance : canonically_ordered_monoid cardinal.{u} :=
{ add_le_add_left := λ a b h c, add_le_add_left _ h,
lt_of_add_lt_add_left := λ a b c, lt_imp_lt_of_le_imp_le (add_le_add_left _),
le_iff_exists_add := @le_iff_exists_add,
..cardinal.comm_semiring, ..cardinal.linear_order }
instance : order_bot cardinal.{u} :=
{ bot := 0, bot_le := zero_le, ..cardinal.linear_order }
theorem cantor : ∀(a : cardinal.{u}), a < 2 ^ a :=
by rw ← prop_eq_two; rintros ⟨a⟩; exact ⟨
⟨⟨λ a b, ⟨a = b⟩, λ a b h, cast (ulift.up.inj (@congr_fun _ _ _ _ h b)).symm rfl⟩⟩,
λ ⟨⟨f, hf⟩⟩, cantor_injective (λ s, f (λ a, ⟨s a⟩)) $
λ s t h, by funext a; injection congr_fun (hf h) a⟩
instance : no_top_order cardinal.{u} :=
{ no_top := λ a, ⟨_, cantor a⟩, ..cardinal.linear_order }
/-- The minimum cardinal in a family of cardinals (the existence
of which is provided by `injective_min`). -/
noncomputable def min {ι} (I : nonempty ι) (f : ι → cardinal) : cardinal :=
f $ classical.some $
@embedding.injective_min _ (λ i, (f i).out) I
theorem min_eq {ι} (I) (f : ι → cardinal) : ∃ i, min I f = f i :=
⟨_, rfl⟩
theorem min_le {ι I} (f : ι → cardinal) (i) : min I f ≤ f i :=
by rw [← mk_out (min I f), ← mk_out (f i)]; exact
let ⟨g⟩ := classical.some_spec
(@embedding.injective_min _ (λ i, (f i).out) I) in
⟨g i⟩
theorem le_min {ι I} {f : ι → cardinal} {a} : a ≤ min I f ↔ ∀ i, a ≤ f i :=
⟨λ h i, le_trans h (min_le _ _),
λ h, let ⟨i, e⟩ := min_eq I f in e.symm ▸ h i⟩
protected theorem wf : @well_founded cardinal.{u} (<) :=
⟨λ a, classical.by_contradiction $ λ h,
let ι := {c :cardinal // ¬ acc (<) c},
f : ι → cardinal := subtype.val,
⟨⟨c, hc⟩, hi⟩ := @min_eq ι ⟨⟨_, h⟩⟩ f in
hc (acc.intro _ (λ j ⟨_, h'⟩,
classical.by_contradiction $ λ hj, h' $
by have := min_le f ⟨j, hj⟩; rwa hi at this))⟩
instance has_wf : @has_well_founded cardinal.{u} := ⟨(<), cardinal.wf⟩
instance wo : @is_well_order cardinal.{u} (<) := ⟨cardinal.wf⟩
/-- The successor cardinal - the smallest cardinal greater than
`c`. This is not the same as `c + 1` except in the case of finite `c`. -/
noncomputable def succ (c : cardinal) : cardinal :=
@min {c' // c < c'} ⟨⟨_, cantor _⟩⟩ subtype.val
theorem lt_succ_self (c : cardinal) : c < succ c :=
by cases min_eq _ _ with s e; rw [succ, e]; exact s.2
theorem succ_le {a b : cardinal} : succ a ≤ b ↔ a < b :=
⟨lt_of_lt_of_le (lt_succ_self _), λ h,
by exact min_le _ (subtype.mk b h)⟩
theorem lt_succ {a b : cardinal} : a < succ b ↔ a ≤ b :=
by rw [← not_le, succ_le, not_lt]
theorem add_one_le_succ (c : cardinal) : c + 1 ≤ succ c :=
begin
refine quot.induction_on c (λ α, _) (lt_succ_self c),
refine quot.induction_on (succ (quot.mk setoid.r α)) (λ β h, _),
cases h.left with f,
have : ¬ surjective f := λ hn,
ne_of_lt h (quotient.sound ⟨equiv.of_bijective ⟨f.inj, hn⟩⟩),
cases classical.not_forall.1 this with b nex,
refine ⟨⟨sum.rec (by exact f) _, _⟩⟩,
{ exact λ _, b },
{ intros a b h, rcases a with a|⟨⟨⟨⟩⟩⟩; rcases b with b|⟨⟨⟨⟩⟩⟩,
{ rw f.inj h },
{ exact nex.elim ⟨_, h⟩ },
{ exact nex.elim ⟨_, h.symm⟩ },
{ refl } }
end
/-- The indexed sum of cardinals is the cardinality of the
indexed disjoint union, i.e. sigma type. -/
def sum {ι} (f : ι → cardinal) : cardinal := mk Σ i, (f i).out
theorem le_sum {ι} (f : ι → cardinal) (i) : f i ≤ sum f :=
by rw ← quotient.out_eq (f i); exact
⟨⟨λ a, ⟨i, a⟩, λ a b h, eq_of_heq $ by injection h⟩⟩
@[simp] theorem sum_mk {ι} (f : ι → Type*) : sum (λ i, mk (f i)) = mk (Σ i, f i) :=
quot.sound ⟨equiv.sigma_congr_right $ λ i,
classical.choice $ quotient.exact $ quot.out_eq $ mk (f i)⟩
theorem sum_const (ι : Type u) (a : cardinal.{u}) : sum (λ _:ι, a) = mk ι * a :=
quotient.induction_on a $ λ α, by simp; exact
quotient.sound ⟨equiv.sigma_equiv_prod _ _⟩
theorem sum_le_sum {ι} (f g : ι → cardinal) (H : ∀ i, f i ≤ g i) : sum f ≤ sum g :=
⟨embedding.sigma_congr_right $ λ i, classical.choice $
by have := H i; rwa [← quot.out_eq (f i), ← quot.out_eq (g i)] at this⟩
/-- The indexed supremum of cardinals is the smallest cardinal above
everything in the family. -/
noncomputable def sup {ι} (f : ι → cardinal) : cardinal :=
@min {c // ∀ i, f i ≤ c} ⟨⟨sum f, le_sum f⟩⟩ (λ a, a.1)
theorem le_sup {ι} (f : ι → cardinal) (i) : f i ≤ sup f :=
by dsimp [sup]; cases min_eq _ _ with c hc; rw hc; exact c.2 i
theorem sup_le {ι} {f : ι → cardinal} {a} : sup f ≤ a ↔ ∀ i, f i ≤ a :=
⟨λ h i, le_trans (le_sup _ _) h,
λ h, by dsimp [sup]; change a with (⟨a, h⟩:subtype _).1; apply min_le⟩
theorem sup_le_sup {ι} (f g : ι → cardinal) (H : ∀ i, f i ≤ g i) : sup f ≤ sup g :=
sup_le.2 $ λ i, le_trans (H i) (le_sup _ _)
theorem sup_le_sum {ι} (f : ι → cardinal) : sup f ≤ sum f :=
sup_le.2 $ le_sum _
theorem sum_le_sup {ι : Type u} (f : ι → cardinal.{u}) : sum f ≤ mk ι * sup.{u u} f :=
by rw ← sum_const; exact sum_le_sum _ _ (le_sup _)
/-- The indexed product of cardinals is the cardinality of the Pi type
(dependent product). -/
def prod {ι : Type u} (f : ι → cardinal) : cardinal := mk (Π i, (f i).out)
@[simp] theorem prod_mk {ι} (f : ι → Type*) : prod (λ i, mk (f i)) = mk (Π i, f i) :=
quot.sound ⟨equiv.Pi_congr_right $ λ i,
classical.choice $ quotient.exact $ mk_out $ mk (f i)⟩
theorem prod_const (ι : Type u) (a : cardinal.{u}) : prod (λ _:ι, a) = a ^ mk ι :=
quotient.induction_on a $ by simp
theorem prod_le_prod {ι} (f g : ι → cardinal) (H : ∀ i, f i ≤ g i) : prod f ≤ prod g :=
⟨embedding.Pi_congr_right $ λ i, classical.choice $
by have := H i; rwa [← mk_out (f i), ← mk_out (g i)] at this⟩
theorem prod_ne_zero {ι} (f : ι → cardinal) : prod f ≠ 0 ↔ ∀ i, f i ≠ 0 :=
begin
conv in (f _) {rw ← mk_out (f i)},
simp [prod, ne_zero_iff_nonempty, -mk_out, -ne.def],
exact ⟨λ ⟨F⟩ i, ⟨F i⟩, λ h, ⟨λ i, classical.choice (h i)⟩⟩,
end
theorem prod_eq_zero {ι} (f : ι → cardinal) : prod f = 0 ↔ ∃ i, f i = 0 :=
not_iff_not.1 $ by simpa using prod_ne_zero f
/-- The universe lift operation on cardinals -/
def lift (c : cardinal.{u}) : cardinal.{max u v} :=
quotient.lift_on c (λ α, ⟦ulift α⟧) $ λ α β ⟨e⟩,
quotient.sound ⟨equiv.ulift.trans $ e.trans equiv.ulift.symm⟩
theorem lift_mk (α) : lift.{u v} (mk α) = mk (ulift.{v u} α) := rfl
theorem lift_umax : lift.{u (max u v)} = lift.{u v} :=
funext $ λ a, quot.induction_on a $ λ α,
quotient.sound ⟨equiv.ulift.trans equiv.ulift.symm⟩
theorem lift_id' (a : cardinal) : lift a = a :=
quot.induction_on a $ λ α, quot.sound ⟨equiv.ulift⟩
@[simp] theorem lift_id : ∀ a, lift.{u u} a = a := lift_id'.{u u}
@[simp] theorem lift_lift (a : cardinal) : lift.{(max u v) w} (lift.{u v} a) = lift.{u (max v w)} a :=
quot.induction_on a $ λ α,
quotient.sound ⟨equiv.ulift.trans $ equiv.ulift.trans equiv.ulift.symm⟩
theorem lift_mk_le {α : Type u} {β : Type v} :
lift.{u (max v w)} (mk α) ≤ lift.{v (max u w)} (mk β) ↔ nonempty (α ↪ β) :=
⟨λ ⟨f⟩, ⟨embedding.congr equiv.ulift equiv.ulift f⟩,
λ ⟨f⟩, ⟨embedding.congr equiv.ulift.symm equiv.ulift.symm f⟩⟩
theorem lift_mk_eq {α : Type u} {β : Type v} :
lift.{u (max v w)} (mk α) = lift.{v (max u w)} (mk β) ↔ nonempty (α ≃ β) :=
quotient.eq.trans
⟨λ ⟨f⟩, ⟨equiv.ulift.symm.trans $ f.trans equiv.ulift⟩,
λ ⟨f⟩, ⟨equiv.ulift.trans $ f.trans equiv.ulift.symm⟩⟩
@[simp] theorem lift_le {a b : cardinal} : lift a ≤ lift b ↔ a ≤ b :=
quotient.induction_on₂ a b $ λ α β,
by rw ← lift_umax; exact lift_mk_le
@[simp] theorem lift_inj {a b : cardinal} : lift a = lift b ↔ a = b :=
by simp [le_antisymm_iff]
@[simp] theorem lift_lt {a b : cardinal} : lift a < lift b ↔ a < b :=
by simp [lt_iff_le_not_le, -not_le]
@[simp] theorem lift_zero : lift 0 = 0 :=
quotient.sound ⟨equiv.ulift.trans equiv.pempty_equiv_pempty⟩
@[simp] theorem lift_one : lift 1 = 1 :=
quotient.sound ⟨equiv.ulift.trans equiv.punit_equiv_punit⟩
@[simp] theorem lift_add (a b) : lift (a + b) = lift a + lift b :=
quotient.induction_on₂ a b $ λ α β,
quotient.sound ⟨equiv.ulift.trans (equiv.sum_congr equiv.ulift equiv.ulift).symm⟩
@[simp] theorem lift_mul (a b) : lift (a * b) = lift a * lift b :=
quotient.induction_on₂ a b $ λ α β,
quotient.sound ⟨equiv.ulift.trans (equiv.prod_congr equiv.ulift equiv.ulift).symm⟩
@[simp] theorem lift_power (a b) : lift (a ^ b) = lift a ^ lift b :=
quotient.induction_on₂ a b $ λ α β,
quotient.sound ⟨equiv.ulift.trans (equiv.arrow_congr equiv.ulift equiv.ulift).symm⟩
@[simp] theorem lift_two_power (a) : lift (2 ^ a) = 2 ^ lift a :=
by simp [bit0]
@[simp] theorem lift_min {ι I} (f : ι → cardinal) : lift (min I f) = min I (lift ∘ f) :=
le_antisymm (le_min.2 $ λ a, lift_le.2 $ min_le _ a) $
let ⟨i, e⟩ := min_eq I (lift ∘ f) in
by rw e; exact lift_le.2 (le_min.2 $ λ j, lift_le.1 $
by have := min_le (lift ∘ f) j; rwa e at this)
theorem lift_down {a : cardinal.{u}} {b : cardinal.{max u v}} :
b ≤ lift a → ∃ a', lift a' = b :=
quotient.induction_on₂ a b $ λ α β,
by dsimp; rw [← lift_id (mk β), ← lift_umax, ← lift_umax.{u v}, lift_mk_le]; exact
λ ⟨f⟩, ⟨mk (set.range f), eq.symm $ lift_mk_eq.2
⟨embedding.equiv_of_surjective
(embedding.cod_restrict _ f set.mem_range_self)
$ λ ⟨a, ⟨b, e⟩⟩, ⟨b, subtype.eq e⟩⟩⟩
theorem le_lift_iff {a : cardinal.{u}} {b : cardinal.{max u v}} :
b ≤ lift a ↔ ∃ a', lift a' = b ∧ a' ≤ a :=
⟨λ h, let ⟨a', e⟩ := lift_down h in ⟨a', e, lift_le.1 $ e.symm ▸ h⟩,
λ ⟨a', e, h⟩, e ▸ lift_le.2 h⟩
theorem lt_lift_iff {a : cardinal.{u}} {b : cardinal.{max u v}} :
b < lift a ↔ ∃ a', lift a' = b ∧ a' < a :=
⟨λ h, let ⟨a', e⟩ := lift_down (le_of_lt h) in
⟨a', e, lift_lt.1 $ e.symm ▸ h⟩,
λ ⟨a', e, h⟩, e ▸ lift_lt.2 h⟩
@[simp] theorem lift_succ (a) : lift (succ a) = succ (lift a) :=
le_antisymm
(le_of_not_gt $ λ h, begin
rcases lt_lift_iff.1 h with ⟨b, e, h⟩,
rw [lt_succ, ← lift_le, e] at h,
exact not_lt_of_le h (lt_succ_self _)
end)
(succ_le.2 $ lift_lt.2 $ lt_succ_self _)
/-- `ω` is the smallest infinite cardinal, also known as ℵ₀. -/
def omega : cardinal.{u} := lift (mk ℕ)
theorem omega_ne_zero : omega ≠ 0 :=
ne_zero_iff_nonempty.2 ⟨⟨0⟩⟩
theorem omega_pos : 0 < omega :=
pos_iff_ne_zero.2 omega_ne_zero
@[simp] theorem lift_omega : lift omega = omega := lift_lift _
@[simp] theorem mk_fin : ∀ (n : ℕ), mk (fin n) = n
| 0 := quotient.sound ⟨(equiv.pempty_of_not_nonempty $ λ ⟨h⟩, h.elim0)⟩
| (n+1) := by rw [nat.cast_succ, ← mk_fin]; exact
quotient.sound (fintype.card_eq.1 $ by simp)
@[simp] theorem lift_nat_cast (n : ℕ) : lift n = n :=
by induction n; simp *
theorem lift_mk_fin (n : ℕ) : lift (mk (fin n)) = n := by simp
theorem fintype_card (α : Type u) [fintype α] : mk α = fintype.card α :=
by rw [← lift_mk_fin.{u}, ← lift_id (mk α), lift_mk_eq.{u 0 u}];
exact fintype.card_eq.1 (by simp)
theorem card_le_of_finset {α} (s : finset α) :
(s.card : cardinal) ≤ cardinal.mk α :=
begin
rw (_ : (s.card : cardinal) = cardinal.mk (↑s : set α)),
{ exact ⟨function.embedding.subtype _⟩ },
rw [cardinal.fintype_card, fintype.card_coe]
end
@[simp] theorem nat_cast_pow {m n : ℕ} : (↑(pow m n) : cardinal) = m ^ n :=
by induction n; simp [nat.pow_succ, -_root_.add_comm, power_add, *]
@[simp] theorem nat_cast_le {m n : ℕ} : (m : cardinal) ≤ n ↔ m ≤ n :=
by rw [← lift_mk_fin, ← lift_mk_fin, lift_le]; exact
⟨λ ⟨⟨f, hf⟩⟩, begin
have : _ = fintype.card _ := finset.card_image_of_injective finset.univ hf,
simp at this,
rw [← fintype.card_fin n, ← this],
exact finset.card_le_of_subset (finset.subset_univ _)
end,
λ h, ⟨⟨λ i, ⟨i.1, lt_of_lt_of_le i.2 h⟩, λ a b h,
have _, from fin.veq_of_eq h, fin.eq_of_veq this⟩⟩⟩
@[simp] theorem nat_cast_lt {m n : ℕ} : (m : cardinal) < n ↔ m < n :=
by simp [lt_iff_le_not_le, -not_le]
@[simp] theorem nat_cast_inj {m n : ℕ} : (m : cardinal) = n ↔ m = n :=
by simp [le_antisymm_iff]
@[simp] theorem nat_succ (n : ℕ) : succ n = n.succ :=
le_antisymm (succ_le.2 $ nat_cast_lt.2 $ nat.lt_succ_self _) (add_one_le_succ _)
@[simp] theorem succ_zero : succ 0 = 1 :=
by simpa using nat_succ 0
theorem cantor' (a) {b : cardinal} (hb : 1 < b) : a < b ^ a :=
by rw [← succ_le, (by simpa using nat_succ 1 : succ 1 = 2)] at hb;
exact lt_of_lt_of_le (cantor _) (power_le_power_right hb)
theorem one_le_iff_pos {c : cardinal} : 1 ≤ c ↔ 0 < c :=
by rw [← succ_zero, succ_le]
theorem one_le_iff_ne_zero {c : cardinal} : 1 ≤ c ↔ c ≠ 0 :=
by rw [one_le_iff_pos, pos_iff_ne_zero]
theorem nat_lt_omega (n : ℕ) : (n : cardinal.{u}) < omega :=
succ_le.1 $ by rw [nat_succ, ← lift_mk_fin, omega, lift_mk_le.{0 0 u}]; exact
⟨⟨fin.val, λ a b, fin.eq_of_veq⟩⟩
theorem one_lt_omega : 1 < omega :=
by simpa using nat_lt_omega 1
theorem lt_omega {c : cardinal.{u}} : c < omega ↔ ∃ n : ℕ, c = n :=
⟨λ h, begin
rcases lt_lift_iff.1 h with ⟨c, rfl, h'⟩,
rcases le_mk_iff_exists_set.1 h'.1 with ⟨S, rfl⟩,
suffices : finite S,
{ cases this, resetI,
existsi fintype.card S,
rw [← lift_nat_cast.{0 u}, lift_inj, fintype_card S] },
by_contra nf,
have P : ∀ (n : ℕ) (IH : ∀ i<n, S), ∃ a : S, ¬ ∃ y h, IH y h = a :=
λ n IH,
let g : {i | i < n} → S := λ ⟨i, h⟩, IH i h in
classical.not_forall.1 (λ h, nf
⟨fintype.of_surjective g (λ a, subtype.exists.2 (h a))⟩),
let F : ℕ → S := nat.lt_wf.fix (λ n IH, classical.some (P n IH)),
refine not_le_of_lt h' ⟨⟨F, _⟩⟩,
suffices : ∀ (n : ℕ) (m < n), F m ≠ F n,
{ refine λ m n, not_imp_not.1 (λ ne, _),
rcases lt_trichotomy m n with h|h|h,
{ exact this n m h },
{ contradiction },
{ exact (this m n h).symm } },
intros n m h,
have := classical.some_spec (P n (λ y _, F y)),
rw [← show F n = classical.some (P n (λ y _, F y)),
from nat.lt_wf.fix_eq (λ n IH, classical.some (P n IH)) n] at this,
exact λ e, this ⟨m, h, e⟩,
end, λ ⟨n, e⟩, e.symm ▸ nat_lt_omega _⟩
theorem omega_le {c : cardinal.{u}} : omega ≤ c ↔ ∀ n : ℕ, (n:cardinal) ≤ c :=
⟨λ h n, le_trans (le_of_lt (nat_lt_omega _)) h,
λ h, le_of_not_lt $ λ hn, begin
rcases lt_omega.1 hn with ⟨n, rfl⟩,
exact not_le_of_lt (nat.lt_succ_self _) (nat_cast_le.1 (h (n+1)))
end⟩
theorem lt_omega_iff_fintype {α : Type u} : mk α < omega ↔ nonempty (fintype α) :=
lt_omega.trans ⟨λ ⟨n, e⟩, begin
rw [← lift_mk_fin n] at e,
cases quotient.exact e with f,
exact ⟨fintype.of_equiv _ f.symm⟩
end, λ ⟨_⟩, by exactI ⟨_, fintype_card _⟩⟩
theorem lt_omega_iff_finite {α} {S : set α} : mk S < omega ↔ finite S :=
lt_omega_iff_fintype
theorem add_lt_omega {a b : cardinal} (ha : a < omega) (hb : b < omega) : a + b < omega :=
match a, b, lt_omega.1 ha, lt_omega.1 hb with
| _, _, ⟨m, rfl⟩, ⟨n, rfl⟩ := by rw [← nat.cast_add]; apply nat_lt_omega
end
theorem mul_lt_omega {a b : cardinal} (ha : a < omega) (hb : b < omega) : a * b < omega :=
match a, b, lt_omega.1 ha, lt_omega.1 hb with
| _, _, ⟨m, rfl⟩, ⟨n, rfl⟩ := by rw [← nat.cast_mul]; apply nat_lt_omega
end
theorem power_lt_omega {a b : cardinal} (ha : a < omega) (hb : b < omega) : a ^ b < omega :=
match a, b, lt_omega.1 ha, lt_omega.1 hb with
| _, _, ⟨m, rfl⟩, ⟨n, rfl⟩ := by rw [← nat_cast_pow]; apply nat_lt_omega
end
/-- König's theorem -/
theorem sum_lt_prod {ι} (f g : ι → cardinal) (H : ∀ i, f i < g i) : sum f < prod g :=
lt_of_not_ge $ λ ⟨F⟩, begin
have : inhabited (Π (i : ι), (g i).out),
{ refine ⟨λ i, classical.choice $ ne_zero_iff_nonempty.1 _⟩,
rw mk_out,
exact ne_of_gt (lt_of_le_of_lt (zero_le _) (H i)) }, resetI,
let G := inv_fun F,
have sG : surjective G := inv_fun_surjective F.2,
choose C hc using show ∀ i, ∃ b, ∀ a, G ⟨i, a⟩ i ≠ b,
{ assume i,
simp only [- not_exists, not_exists.symm, classical.not_forall.symm],
refine λ h, not_le_of_lt (H i) _,
rw [← mk_out (f i), ← mk_out (g i)],
exact ⟨embedding.of_surjective h⟩ },
exact (let ⟨⟨i, a⟩, h⟩ := sG C in hc i a (congr_fun h _))
end
@[simp] theorem mk_empty : mk empty = 0 :=
fintype_card empty
@[simp] theorem mk_pempty : mk pempty = 0 :=
fintype_card pempty
@[simp] theorem mk_plift_of_false {p : Prop} (h : ¬ p) : mk (plift p) = 0 :=
quotient.sound ⟨equiv.plift.trans $ equiv.equiv_pempty h⟩
@[simp] theorem mk_unit : mk unit = 1 :=
(fintype_card unit).trans nat.cast_one
@[simp] theorem mk_punit : mk punit = 1 :=
(fintype_card punit).trans nat.cast_one
@[simp] theorem mk_singleton {α : Type u} (x : α) : mk ({x} : set α) = 1 :=
quotient.sound ⟨equiv.set.singleton x⟩
@[simp] theorem mk_plift_of_true {p : Prop} (h : p) : mk (plift p) = 1 :=
quotient.sound ⟨equiv.plift.trans $ equiv.prop_equiv_punit h⟩
@[simp] theorem mk_bool : mk bool = 2 :=
quotient.sound ⟨equiv.bool_equiv_punit_sum_punit⟩
@[simp] theorem mk_Prop : mk Prop = 2 :=
(quotient.sound ⟨equiv.Prop_equiv_bool⟩ : mk Prop = mk bool).trans mk_bool
@[simp] theorem mk_option {α : Type u} : mk (option α) = mk α + 1 :=
quotient.sound ⟨equiv.option_equiv_sum_punit α⟩
theorem mk_list_eq_sum_pow (α : Type u) : mk (list α) = sum (λ n : ℕ, (mk α)^(n:cardinal.{u})) :=
calc mk (list α)
= mk (Σ n, vector α n) : quotient.sound ⟨equiv.equiv_sigma_subtype list.length⟩
... = mk (Σ n, fin n → α) : quotient.sound ⟨equiv.sigma_congr_right $ λ n,
⟨vector.nth, vector.of_fn, vector.of_fn_nth, λ f, funext $ vector.nth_of_fn f⟩⟩
... = mk (Σ n : ℕ, ulift.{u} (fin n) → α) : quotient.sound ⟨equiv.sigma_congr_right $ λ n,
equiv.arrow_congr equiv.ulift.symm (equiv.refl α)⟩
... = sum (λ n : ℕ, (mk α)^(n:cardinal.{u})) : by simp only [(lift_mk_fin _).symm, lift_mk, power_def, sum_mk]
theorem mk_quot_le {α : Type u} {r : α → α → Prop} : mk (quot r) ≤ mk α :=
mk_le_of_surjective quot.exists_rep
theorem mk_quotient_le {α : Type u} {s : setoid α} : mk (quotient s) ≤ mk α :=
mk_quot_le
theorem mk_subtype_le {α : Type u} {s : set α} : mk s ≤ mk α :=
mk_le_of_injective subtype.val_injective
@[simp] theorem mk_emptyc (α : Type u) : mk (∅ : set α) = 0 :=
quotient.sound ⟨equiv.set.pempty α⟩
theorem mk_univ {α : Type u} : mk (@univ α) = mk α :=
quotient.sound ⟨equiv.set.univ α⟩
theorem mk_image_le {α β : Type u} {f : α → β} {s : set α} : mk (f '' s) ≤ mk s :=
mk_le_of_surjective surjective_onto_image
theorem mk_range_le {α β : Type u} {f : α → β} {s : set α} : mk (range f) ≤ mk α :=
mk_le_of_surjective surjective_onto_range
theorem mk_eq_of_injective {α β : Type u} {f : α → β} {s : set α} (hf : injective f) :
mk (f '' s) = mk s :=
quotient.sound ⟨(equiv.set.image f s hf).symm⟩
theorem mk_Union_le_sum_mk {α ι : Type u} {f : ι → set α} : mk (⋃ i, f i) ≤ sum (λ i, mk (f i)) :=
calc mk (⋃ i, f i) ≤ mk (Σ i, f i) : mk_le_of_surjective (set.surjective_sigma_to_Union f)
... = sum (λ i, mk (f i)) : (sum_mk _).symm
theorem mk_Union_eq_sum_mk {α ι : Type u} {f : ι → set α} (h : ∀i j, i ≠ j → disjoint (f i) (f j)) :
mk (⋃ i, f i) = sum (λ i, mk (f i)) :=
calc mk (⋃ i, f i) = mk (Σi, f i) : quot.sound ⟨set.Union_eq_sigma_of_disjoint h⟩
... = sum (λi, mk (f i)) : (sum_mk _).symm
@[simp] lemma finset_card {α : Type u} {s : finset α} : ↑(finset.card s) = mk (↑s : set α) :=
by rw [fintype_card, nat_cast_inj, fintype.card_coe]
theorem mk_union_add_mk_inter {α : Type u} {S T : set α} : mk (S ∪ T : set α) + mk (S ∩ T : set α) = mk S + mk T :=
quot.sound ⟨equiv.set.union_sum_inter S T⟩
theorem mk_union_of_disjoint {α : Type u} {S T : set α} (H : disjoint S T) : mk (S ∪ T : set α) = mk S + mk T :=
quot.sound ⟨equiv.set.union (disjoint_iff.1 H)⟩
lemma mk_le_mk_of_subset {α} {s t : set α} (h : s ⊆ t) : mk s ≤ mk t :=
⟨ set.embedding_of_subset h ⟩
end cardinal
|
4fc1ff2dcfc77b1617a3c8bf61f2222df2b75d03 | 246309748072bf9f8da313401699689ebbecd94d | /src/ring_theory/polynomial/rational_root.lean | 8b98cd44547358da52771e7dda31ea9dc5f4bc44 | [
"Apache-2.0"
] | permissive | YJMD/mathlib | b703a641e5f32a996f7842f7c0043bab2b462ee2 | 7310eab9fa8c1b1229dca42682f1fa6bfb7dbbf9 | refs/heads/master | 1,670,714,479,314 | 1,599,035,445,000 | 1,599,035,445,000 | 292,279,930 | 0 | 0 | null | 1,599,050,561,000 | 1,599,050,560,000 | null | UTF-8 | Lean | false | false | 9,555 | lean | /-
Copyright (c) 2020 Anne Baanen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Anne Baanen
-/
import ring_theory.polynomial.basic
import ring_theory.localization
/-!
# Rational root theorem and integral root theorem
This file contains the rational root theorem and integral root theorem.
The rational root theorem for a unique factorization domain `A`
with localization `S`, states that the roots of `p : polynomial A` in `A`'s
field of fractions are of the form `x / y` with `x y : A`, `x ∣ p.coeff 0` and
`y ∣ p.leading_coeff`.
The corollary is the integral root theorem `is_integer_of_is_root_of_monic`:
if `p` is monic, its roots must be integers.
Finally, we use this to show unique factorization domains are integrally closed.
## References
* https://en.wikipedia.org/wiki/Rational_root_theorem
-/
section scale_roots
variables {A K R S : Type*} [integral_domain A] [field K] [comm_ring R] [comm_ring S]
variables {M : submonoid A} {f : localization_map M S} {g : fraction_map A K}
open finsupp polynomial
/-- `scale_roots p s` is a polynomial with root `r * s` for each root `r` of `p`. -/
noncomputable def scale_roots (p : polynomial R) (s : R) : polynomial R :=
on_finset p.support
(λ i, coeff p i * s ^ (p.nat_degree - i))
(λ i h, mem_support_iff.mpr (left_ne_zero_of_mul h))
@[simp] lemma coeff_scale_roots (p : polynomial R) (s : R) (i : ℕ) :
(scale_roots p s).coeff i = coeff p i * s ^ (p.nat_degree - i) :=
rfl
lemma coeff_scale_roots_nat_degree (p : polynomial R) (s : R) :
(scale_roots p s).coeff p.nat_degree = p.leading_coeff :=
by rw [leading_coeff, coeff_scale_roots, nat.sub_self, pow_zero, mul_one]
@[simp] lemma zero_scale_roots (s : R) : scale_roots 0 s = 0 := by { ext, simp }
lemma scale_roots_ne_zero {p : polynomial R} (hp : p ≠ 0) (s : R) :
scale_roots p s ≠ 0 :=
begin
intro h,
have : p.coeff p.nat_degree ≠ 0 := mt leading_coeff_eq_zero.mp hp,
have : (scale_roots p s).coeff p.nat_degree = 0 :=
congr_fun (congr_arg (coeff : polynomial R → ℕ → R) h) p.nat_degree,
rw [coeff_scale_roots_nat_degree] at this,
contradiction
end
lemma support_scale_roots_le (p : polynomial R) (s : R) :
(scale_roots p s).support ≤ p.support :=
begin
intros i,
simp only [mem_support_iff, scale_roots, on_finset_apply],
exact left_ne_zero_of_mul
end
lemma support_scale_roots_eq (p : polynomial R) {s : R} (hs : s ∈ non_zero_divisors R) :
(scale_roots p s).support = p.support :=
le_antisymm (support_scale_roots_le p s)
begin
intro i,
simp only [mem_support_iff, scale_roots, on_finset_apply],
intros p_ne_zero ps_zero,
have := ((non_zero_divisors R).pow_mem hs (p.nat_degree - i)) _ ps_zero,
contradiction
end
@[simp] lemma degree_scale_roots (p : polynomial R) {s : R} :
degree (scale_roots p s) = degree p :=
begin
haveI := classical.prop_decidable,
by_cases hp : p = 0,
{ rw [hp, zero_scale_roots] },
have := scale_roots_ne_zero hp s,
refine le_antisymm (finset.sup_mono (support_scale_roots_le p s)) (degree_le_degree _),
rw coeff_scale_roots_nat_degree,
intro h,
have := leading_coeff_eq_zero.mp h,
contradiction,
end
@[simp] lemma nat_degree_scale_roots (p : polynomial R) (s : R) :
nat_degree (scale_roots p s) = nat_degree p :=
by simp only [nat_degree, degree_scale_roots]
lemma monic_scale_roots_iff {p : polynomial R} (s : R) :
monic (scale_roots p s) ↔ monic p :=
by simp [monic, leading_coeff]
lemma scale_roots_eval₂_eq_zero {p : polynomial S} (f : S →+* R)
{r : R} {s : S} (hr : eval₂ f r p = 0) (hs : s ∈ non_zero_divisors S) :
eval₂ f (f s * r) (scale_roots p s) = 0 :=
calc eval₂ f (f s * r) (scale_roots p s) =
(scale_roots p s).support.sum (λ i, f (coeff p i * s ^ (p.nat_degree - i)) * (f s * r) ^ i) : eval₂_eq_sum
... = p.support.sum (λ (i : ℕ), f (p.coeff i) * f s ^ (p.nat_degree - i + i) * r ^ i) :
finset.sum_congr (support_scale_roots_eq p hs)
(λ i hi, by simp_rw [f.map_mul, f.map_pow, pow_add, mul_pow, mul_assoc])
... = p.support.sum (λ (i : ℕ), f s ^ p.nat_degree * (f (p.coeff i) * r ^ i)) :
finset.sum_congr rfl
(λ i hi, by { rw [mul_assoc, mul_left_comm, nat.sub_add_cancel],
exact le_nat_degree_of_ne_zero (mem_support_iff.mp hi) })
... = f s ^ p.nat_degree * p.support.sum (λ (i : ℕ), (f (p.coeff i) * r ^ i)) : finset.mul_sum.symm
... = f s ^ p.nat_degree * eval₂ f r p : by { rw [eval₂_eq_sum], refl }
... = 0 : by rw [hr, _root_.mul_zero]
lemma scale_roots_aeval_eq_zero [algebra S R] {p : polynomial S}
{r : R} {s : S} (hr : aeval r p = 0) (hs : s ∈ non_zero_divisors S) :
aeval (algebra_map S R s * r) (scale_roots p s) = 0 :=
scale_roots_eval₂_eq_zero (algebra_map S R) hr hs
lemma scale_roots_eval₂_eq_zero_of_eval₂_div_eq_zero
{p : polynomial A} {f : A →+* K} (hf : function.injective f)
{r s : A} (hr : eval₂ f (f r / f s) p = 0) (hs : s ∈ non_zero_divisors A) :
eval₂ f (f r) (scale_roots p s) = 0 :=
begin
convert scale_roots_eval₂_eq_zero f hr hs,
rw [←mul_div_assoc, mul_comm, mul_div_cancel],
exact @map_ne_zero_of_mem_non_zero_divisors _ _ _ _ _ hf ⟨s, hs⟩
end
lemma scale_roots_aeval_eq_zero_of_aeval_div_eq_zero [algebra A K]
(inj : function.injective (algebra_map A K)) {p : polynomial A} {r s : A}
(hr : aeval (algebra_map A K r / algebra_map A K s) p = 0) (hs : s ∈ non_zero_divisors A) :
aeval (algebra_map A K r) (scale_roots p s) = 0 :=
scale_roots_eval₂_eq_zero_of_eval₂_div_eq_zero inj hr hs
lemma scale_roots_aeval_eq_zero_of_aeval_mk'_eq_zero {p : polynomial A} {r : A} {s : M}
(hr : @aeval A f.codomain _ _ _ (f.mk' r s) p = 0) (hM : M ≤ non_zero_divisors A) :
@aeval A f.codomain _ _ _ (f.to_map r) (scale_roots p s) = 0 :=
begin
convert scale_roots_eval₂_eq_zero f.to_map hr (hM s.2),
rw aeval_def,
congr,
apply (f.mk'_spec' r s).symm
end
lemma num_is_root_scale_roots_of_aeval_eq_zero
[unique_factorization_domain A] (g : fraction_map A K)
{p : polynomial A} {x : g.codomain} (hr : aeval x p = 0) :
is_root (scale_roots p (g.denom x)) (g.num x) :=
begin
apply is_root_of_eval₂_map_eq_zero g.injective,
refine scale_roots_aeval_eq_zero_of_aeval_mk'_eq_zero _ (le_refl (non_zero_divisors A)),
rw g.mk'_num_denom,
exact hr
end
end scale_roots
section rational_root_theorem
variables {A K : Type*} [integral_domain A] [unique_factorization_domain A] [field K]
variables {f : fraction_map A K}
open polynomial unique_factorization_domain
/-- Rational root theorem part 1:
if `r : f.codomain` is a root of a polynomial over the ufd `A`,
then the numerator of `r` divides the constant coefficient -/
theorem num_dvd_of_is_root {p : polynomial A} {r : f.codomain} (hr : aeval r p = 0) :
f.num r ∣ p.coeff 0 :=
begin
suffices : f.num r ∣ (scale_roots p (f.denom r)).coeff 0,
{ simp only [coeff_scale_roots, nat.sub_zero] at this,
haveI := classical.prop_decidable,
by_cases hr : f.num r = 0,
{ obtain ⟨u, hu⟩ := is_unit_pow p.nat_degree (f.is_unit_denom_of_num_eq_zero hr),
rw ←hu at this,
exact units.dvd_mul_right.mp this },
{ refine dvd_of_dvd_mul_left_of_no_prime_factors hr _ this,
intros q dvd_num dvd_denom_pow hq,
apply hq.not_unit,
exact f.num_denom_reduced r dvd_num (hq.dvd_of_dvd_pow dvd_denom_pow) } },
convert dvd_term_of_is_root_of_dvd_terms 0 (num_is_root_scale_roots_of_aeval_eq_zero f hr) _,
{ rw [pow_zero, mul_one] },
intros j hj,
apply dvd_mul_of_dvd_right,
convert pow_dvd_pow (f.num r) (nat.succ_le_of_lt (bot_lt_iff_ne_bot.mpr hj)),
exact (pow_one _).symm
end
/-- Rational root theorem part 2:
if `r : f.codomain` is a root of a polynomial over the ufd `A`,
then the denominator of `r` divides the leading coefficient -/
theorem denom_dvd_of_is_root {p : polynomial A} {r : f.codomain} (hr : aeval r p = 0) :
(f.denom r : A) ∣ p.leading_coeff :=
begin
suffices : (f.denom r : A) ∣ p.leading_coeff * f.num r ^ p.nat_degree,
{ refine dvd_of_dvd_mul_left_of_no_prime_factors
(mem_non_zero_divisors_iff_ne_zero.mp (f.denom r).2) _ this,
intros q dvd_denom dvd_num_pow hq,
apply hq.not_unit,
exact f.num_denom_reduced r (hq.dvd_of_dvd_pow dvd_num_pow) dvd_denom },
rw ←coeff_scale_roots_nat_degree,
apply dvd_term_of_is_root_of_dvd_terms _ (num_is_root_scale_roots_of_aeval_eq_zero f hr),
intros j hj,
by_cases h : j < p.nat_degree,
{ refine dvd_mul_of_dvd_left (dvd_mul_of_dvd_right _ _) _,
convert pow_dvd_pow _ (nat.succ_le_iff.mpr (nat.lt_sub_left_of_add_lt _)),
{ exact (pow_one _).symm },
simpa using h },
rw [←nat_degree_scale_roots p (f.denom r)] at *,
rw [coeff_eq_zero_of_nat_degree_lt (lt_of_le_of_ne (le_of_not_gt h) hj.symm), zero_mul],
exact dvd_zero _
end
/-- Integral root theorem:
if `r : f.codomain` is a root of a monic polynomial over the ufd `A`,
then `r` is an integer -/
theorem is_integer_of_is_root_of_monic {p : polynomial A} (hp : monic p) {r : f.codomain}
(hr : aeval r p = 0) : f.is_integer r :=
f.is_integer_of_is_unit_denom (is_unit_of_dvd_one _ (hp ▸ denom_dvd_of_is_root hr))
namespace unique_factorization_domain
lemma integer_of_integral {x : f.codomain} :
is_integral A x → f.is_integer x :=
λ ⟨p, hp, hx⟩, is_integer_of_is_root_of_monic hp hx
lemma integrally_closed : integral_closure A f.codomain = ⊥ :=
eq_bot_iff.mpr (λ x hx, algebra.mem_bot.mpr (integer_of_integral hx))
end unique_factorization_domain
end rational_root_theorem
|
7f197568e3c601a5ccfc7df2ae7285a44f5b9963 | 1546f9083f4babf70df0329497d1ee05adc8c665 | /src/monoidal_categories_reboot/monoidal_category.lean | a2d823b8ea692a855a0a8716ee5ea34c1f2e8cd2 | [
"Apache-2.0"
] | permissive | khoek/monoidal-categories-reboot | 0899b0d4552ff039388042059c91f7207c6c34e5 | ed3df8ecce5d4e3d95cb858911bad12bb632cf8a | refs/heads/master | 1,588,877,903,131 | 1,554,987,273,000 | 1,554,987,273,000 | 180,791,863 | 0 | 0 | null | 1,554,987,295,000 | 1,554,987,295,000 | null | UTF-8 | Lean | false | false | 10,485 | lean | -- Copyright (c) 2018 Michael Jendrusch. All rights reserved.
import category_theory.category
import category_theory.functor
import category_theory.products
import category_theory.natural_isomorphism
import category_theory.tactics.obviously -- Give ourselves access to `rewrite_search`
import .slice_tactic
import .tensor_product
open category_theory
open category_theory.slice
open tactic
universes u v
open category_theory.category
open category_theory.functor
open category_theory.prod
open category_theory.functor.category.nat_trans
open category_theory.nat_iso
namespace category_theory.monoidal
class monoidal_category (C : Sort u) extends category.{v} C :=
-- curried tensor product of objects:
(tensor_obj : C → C → C)
-- curried tensor product of morphisms:
(tensor_hom : Π {X₁ Y₁ X₂ Y₂ : C}, hom X₁ Y₁ → hom X₂ Y₂ → hom (tensor_obj X₁ X₂) (tensor_obj Y₁ Y₂))
-- tensor product laws:
(tensor_map_id' : ∀ (X₁ X₂ : C), tensor_hom (𝟙 X₁) (𝟙 X₂) = 𝟙 (tensor_obj X₁ X₂) . obviously)
(tensor_map_comp' : ∀ {X₁ Y₁ Z₁ X₂ Y₂ Z₂ : C} (f₁ : X₁ ⟶ Y₁) (f₂ : X₂ ⟶ Y₂) (g₁ : Y₁ ⟶ Z₁) (g₂ : Y₂ ⟶ Z₂),
tensor_hom (f₁ ≫ g₁) (f₂ ≫ g₂) = (tensor_hom f₁ f₂) ≫ (tensor_hom g₁ g₂) . obviously)
-- tensor unit:
(tensor_unit : C)
-- associator:
(associator : Π X Y Z : C, (tensor_obj (tensor_obj X Y) Z) ≅ (tensor_obj X (tensor_obj Y Z)))
(associator_naturality' : assoc_natural tensor_obj @tensor_hom associator . obviously)
-- left unitor:
(left_unitor : Π X : C, tensor_obj tensor_unit X ≅ X)
(left_unitor_naturality' : left_unitor_natural tensor_obj @tensor_hom tensor_unit left_unitor . obviously)
-- right unitor:
(right_unitor : Π X : C, tensor_obj X tensor_unit ≅ X)
(right_unitor_naturality' : right_unitor_natural tensor_obj @tensor_hom tensor_unit right_unitor . obviously)
-- pentagon identity:
(pentagon' : pentagon @tensor_hom associator . obviously)
-- triangle identity:
(triangle' : triangle @tensor_hom left_unitor right_unitor associator . obviously)
restate_axiom monoidal_category.tensor_map_id'
attribute [simp,search] monoidal_category.tensor_map_id
restate_axiom monoidal_category.tensor_map_comp'
attribute [simp,search] monoidal_category.tensor_map_comp
restate_axiom monoidal_category.associator_naturality'
attribute [search] monoidal_category.associator_naturality
restate_axiom monoidal_category.left_unitor_naturality'
attribute [search] monoidal_category.left_unitor_naturality
restate_axiom monoidal_category.right_unitor_naturality'
attribute [search] monoidal_category.right_unitor_naturality
restate_axiom monoidal_category.pentagon'
attribute [search] monoidal_category.pentagon
restate_axiom monoidal_category.triangle'
attribute [search] monoidal_category.triangle
@[obviously] meta def obviously'' := tactic.tidy {tactics := tidy.default_tactics ++ [rewrite_search {}]}
section
open monoidal_category
def one {C : Sort u} [monoidal_category.{u v} C] (X : C) : X ≅ X :=
{ hom := 𝟙 X,
inv := 𝟙 X }
def tensor_iso {C : Sort u} {X Y X' Y' : C} [monoidal_category.{u v} C] (f : X ≅ Y) (g : X' ≅ Y') :
tensor_obj X X' ≅ tensor_obj Y Y' :=
{ hom := tensor_hom f.hom g.hom,
inv := tensor_hom f.inv g.inv}
end
section
variables (C : Type u) [𝒞 : monoidal_category.{(u + 1) (v + 1)} C]
include 𝒞
instance : category C := 𝒞.to_category
open monoidal_category
infixr ` ⊗ `:80 := tensor_obj
infixr ` ⊗ `:80 := tensor_hom
infixr ` ⊗ `:80 := tensor_iso
@[reducible] def monoidal_category.tensor : (C × C) ⥤ C :=
{ obj := λ X, X.1 ⊗ X.2,
map := λ {X Y : C × C} (f : X ⟶ Y), f.1 ⊗ f.2 }
variables {U V W X Y Z : C}
@[search] definition interchange (f : U ⟶ V) (g : V ⟶ W) (h : X ⟶ Y) (k : Y ⟶ Z)
: (f ≫ g) ⊗ (h ≫ k) = (f ⊗ h) ≫ (g ⊗ k) :=
tensor_map_comp C f h g k
@[simp,search] lemma interchange_left_identity (f : W ⟶ X) (g : X ⟶ Y) :
(f ⊗ (𝟙 Z)) ≫ (g ⊗ (𝟙 Z)) = (f ≫ g) ⊗ (𝟙 Z) :=
begin
rw ←interchange,
simp
end
@[simp,search] lemma interchange_right_identity (f : W ⟶ X) (g : X ⟶ Y) :
(𝟙 Z ⊗ f) ≫ (𝟙 Z ⊗ g) = (𝟙 Z) ⊗ (f ≫ g) :=
begin
rw ←interchange,
simp
end
@[search] lemma interchange_identities (f : W ⟶ X) (g : Y ⟶ Z) :
((𝟙 Y) ⊗ f) ≫ (g ⊗ (𝟙 X)) = (g ⊗ (𝟙 W)) ≫ ((𝟙 Z) ⊗ f) :=
begin
rw ←interchange,
rw ←interchange,
simp
end
open monoidal_category
@[reducible] def monoidal_category.left_assoc_functor : (C × C × C) ⥤ C :=
{ obj := λ X, (X.1 ⊗ X.2.1) ⊗ X.2.2,
map := λ {X Y : C × C × C} (f : X ⟶ Y),
(f.1 ⊗ f.2.1) ⊗ f.2.2 }
@[reducible] def monoidal_category.right_assoc_functor : (C × C × C) ⥤ C :=
{ obj := λ X, X.1 ⊗ (X.2.1 ⊗ X.2.2),
map := λ {X Y : C × C × C} (f : X ⟶ Y),
f.1 ⊗ (f.2.1 ⊗ f.2.2) }
@[reducible] def monoidal_category.left_unitor_functor : C ⥤ C :=
{ obj := λ X, tensor_unit C ⊗ X,
map := λ {X Y : C} (f : X ⟶ Y), (𝟙 (tensor_unit C)) ⊗ f }
@[reducible] def monoidal_category.right_unitor_functor : C ⥤ C :=
{ obj := λ X, X ⊗ tensor_unit C,
map := λ {X Y : C} (f : X ⟶ Y), f ⊗ (𝟙 (tensor_unit C)) }
open monoidal_category
-- natural isomorphisms for the associator and unitors.
@[reducible] def monoidal_category.associator_nat_iso :
left_assoc_functor C ≅ right_assoc_functor C :=
nat_iso.of_components
(by intros; simp; apply category_theory.monoidal.monoidal_category.associator)
(by intros; simp; apply associator_naturality)
@[reducible] def monoidal_category.left_unitor_nat_iso :
left_unitor_functor C ≅ functor.id C :=
nat_iso.of_components
(by intros; simp; apply category_theory.monoidal.monoidal_category.left_unitor)
(by intros; simp; apply left_unitor_naturality)
@[reducible] def monoidal_category.right_unitor_nat_iso :
right_unitor_functor C ≅ functor.id C :=
nat_iso.of_components
(by intros; simp; apply category_theory.monoidal.monoidal_category.right_unitor)
(by intros; simp; apply right_unitor_naturality)
instance tensor_iso_of_iso
{X Y X' Y' : C} (f : X ⟶ Y) (g : X' ⟶ Y')
[is_iso f] [is_iso g] : is_iso (f ⊗ g) :=
{ inv := (is_iso.inv f) ⊗ (is_iso.inv g) }
@[simp,search] lemma tensor_left_equiv
{X Y : C} (f g : X ⟶ Y) :
((𝟙 (tensor_unit C)) ⊗ f = (𝟙 (tensor_unit C)) ⊗ g) ↔ (f = g) :=
sorry
@[simp,search] lemma tensor_right_equiv
{X Y : C} (f g : X ⟶ Y) :
(f ⊗ (𝟙 (tensor_unit C)) = g ⊗ (𝟙 (tensor_unit C))) ↔ (f = g) :=
sorry
-- proof following the nLab:
@[search] lemma left_unitor_product_aux_perimeter (X Y : C) :
((associator (tensor_unit C) (tensor_unit C) X).hom ⊗ (𝟙 Y)) ≫
(associator (tensor_unit C) ((tensor_unit C) ⊗ X) Y).hom ≫
((𝟙 (tensor_unit C)) ⊗ (associator (tensor_unit C) X Y).hom) ≫
((𝟙 (tensor_unit C)) ⊗ (left_unitor (X ⊗ Y)).hom)
= (((right_unitor (tensor_unit C)).hom ⊗ (𝟙 X)) ⊗ (𝟙 Y)) ≫
(associator (tensor_unit C) X Y).hom := by obviously
@[search] lemma left_unitor_product_aux_triangle (X Y : C) :
((associator (tensor_unit C) (tensor_unit C) X).hom ⊗ (𝟙 Y)) ≫
(((𝟙 (tensor_unit C)) ⊗ (left_unitor X).hom) ⊗ (𝟙 Y))
= ((right_unitor (tensor_unit C)).hom ⊗ (𝟙 X)) ⊗ (𝟙 Y) := by obviously
@[search] lemma left_unitor_product_aux_square (X Y : C) :
(associator (tensor_unit C) ((tensor_unit C) ⊗ X) Y).hom ≫
((𝟙 (tensor_unit C)) ⊗ (left_unitor X).hom ⊗ (𝟙 Y))
= (((𝟙 (tensor_unit C)) ⊗ (left_unitor X).hom) ⊗ (𝟙 Y)) ≫
(associator (tensor_unit C) X Y).hom := by obviously
@[search] lemma left_unitor_product_aux (X Y : C) :
((𝟙 (tensor_unit C)) ⊗ (associator (tensor_unit C) X Y).hom) ≫
((𝟙 (tensor_unit C)) ⊗ (left_unitor (X ⊗ Y)).hom)
= (𝟙 (tensor_unit C)) ⊗ ((left_unitor X).hom ⊗ (𝟙 Y)) :=
begin
rw <-(cancel_epi (associator (tensor_unit C) ((tensor_unit C) ⊗ X) Y).hom),
rw left_unitor_product_aux_square,
rw <-(cancel_epi ((associator (tensor_unit C) (tensor_unit C) X).hom ⊗ (𝟙 Y))),
conv {
to_rhs,
slice 1 2,
rw left_unitor_product_aux_triangle,
},
obviously
end
@[search] lemma right_unitor_product_aux_perimeter (X Y : C) :
((associator X Y (tensor_unit C)).hom ⊗ (𝟙 (tensor_unit C))) ≫
(associator X (Y ⊗ (tensor_unit C)) (tensor_unit C)).hom ≫
((𝟙 X) ⊗ (associator Y (tensor_unit C) (tensor_unit C)).hom) ≫
((𝟙 X) ⊗ (𝟙 Y) ⊗ (left_unitor (tensor_unit C)).hom)
= ((right_unitor (X ⊗ Y)).hom ⊗ (𝟙 (tensor_unit C))) ≫
(associator X Y (tensor_unit C)).hom := by obviously
@[search] lemma right_unitor_product_aux_triangle (X Y : C) :
((𝟙 X) ⊗ (associator Y (tensor_unit C) (tensor_unit C)).hom) ≫
((𝟙 X) ⊗ (𝟙 Y) ⊗ (left_unitor (tensor_unit C)).hom)
= (𝟙 X) ⊗ (right_unitor Y).hom ⊗ (𝟙 (tensor_unit C)) := by obviously
@[search] lemma right_unitor_product_aux_square (X Y : C) :
(associator X (Y ⊗ (tensor_unit C)) (tensor_unit C)).hom ≫
((𝟙 X) ⊗ (right_unitor Y).hom ⊗ (𝟙 (tensor_unit C)))
= (((𝟙 X) ⊗ (right_unitor Y).hom) ⊗ (𝟙 (tensor_unit C))) ≫
(associator X Y (tensor_unit C)).hom := by obviously
@[search] lemma right_unitor_product_aux (X Y : C) :
((associator X Y (tensor_unit C)).hom ⊗ (𝟙 (tensor_unit C))) ≫
(((𝟙 X) ⊗ (right_unitor Y).hom) ⊗ (𝟙 (tensor_unit C)))
= ((right_unitor (X ⊗ Y)).hom ⊗ (𝟙 (tensor_unit C))) :=
begin
rw <-(cancel_mono (associator X Y (tensor_unit C)).hom),
conv {
to_lhs,
slice 2 3,
rw <-right_unitor_product_aux_square,
},
obviously
end
@[search] lemma left_unitor_product (X Y : C) :
((associator (tensor_unit C) X Y).hom) ≫
((left_unitor (X ⊗ Y)).hom)
= ((left_unitor X).hom ⊗ (𝟙 Y)) :=
begin
rw <-tensor_left_equiv,
rw <-interchange_right_identity,
apply left_unitor_product_aux
end
@[search] lemma right_unitor_product (X Y : C) :
((associator X Y (tensor_unit C)).hom) ≫
((𝟙 X) ⊗ (right_unitor Y).hom)
= ((right_unitor (X ⊗ Y)).hom) :=
begin
rw <-tensor_right_equiv,
rw <-interchange_left_identity,
apply right_unitor_product_aux
end
end
end category_theory.monoidal
|
e0a012ee1b2704e0b050a3a16455eafbe0649f61 | 491068d2ad28831e7dade8d6dff871c3e49d9431 | /hott/init/funext.hlean | 84644ebf7ab77520e2e794e01d757b6b38946de9 | [
"Apache-2.0"
] | permissive | davidmueller13/lean | 65a3ed141b4088cd0a268e4de80eb6778b21a0e9 | c626e2e3c6f3771e07c32e82ee5b9e030de5b050 | refs/heads/master | 1,611,278,313,401 | 1,444,021,177,000 | 1,444,021,177,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 10,472 | hlean | /-
Copyright (c) 2014 Jakob von Raumer. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jakob von Raumer
Ported from Coq HoTT
-/
prelude
import .trunc .equiv .ua
open eq is_trunc sigma function is_equiv equiv prod unit prod.ops lift
/-
We now prove that funext follows from a couple of weaker-looking forms
of function extensionality.
This proof is originally due to Voevodsky; it has since been simplified
by Peter Lumsdaine and Michael Shulman.
-/
definition funext.{l k} :=
Π ⦃A : Type.{l}⦄ {P : A → Type.{k}} (f g : Π x, P x), is_equiv (@apd10 A P f g)
-- Naive funext is the simple assertion that pointwise equal functions are equal.
definition naive_funext :=
Π ⦃A : Type⦄ {P : A → Type} (f g : Πx, P x), (f ~ g) → f = g
-- Weak funext says that a product of contractible types is contractible.
definition weak_funext :=
Π ⦃A : Type⦄ (P : A → Type) [H: Πx, is_contr (P x)], is_contr (Πx, P x)
definition weak_funext_of_naive_funext : naive_funext → weak_funext :=
(λ nf A P (Pc : Πx, is_contr (P x)),
let c := λx, center (P x) in
is_contr.mk c (λ f,
have eq' : (λx, center (P x)) ~ f,
from (λx, center_eq (f x)),
have eq : (λx, center (P x)) = f,
from nf A P (λx, center (P x)) f eq',
eq
)
)
/-
The less obvious direction is that weak_funext implies funext
(and hence all three are logically equivalent). The point is that under weak
funext, the space of "pointwise homotopies" has the same universal property as
the space of paths.
-/
section
universe variables l k
parameters [wf : weak_funext.{l k}] {A : Type.{l}} {B : A → Type.{k}} (f : Π x, B x)
definition is_contr_sigma_homotopy : is_contr (Σ (g : Π x, B x), f ~ g) :=
is_contr.mk (sigma.mk f (homotopy.refl f))
(λ dp, sigma.rec_on dp
(λ (g : Π x, B x) (h : f ~ g),
let r := λ (k : Π x, Σ y, f x = y),
@sigma.mk _ (λg, f ~ g)
(λx, pr1 (k x)) (λx, pr2 (k x)) in
let s := λ g h x, @sigma.mk _ (λy, f x = y) (g x) (h x) in
have t1 : Πx, is_contr (Σ y, f x = y),
from (λx, !is_contr_sigma_eq),
have t2 : is_contr (Πx, Σ y, f x = y),
from !wf,
have t3 : (λ x, @sigma.mk _ (λ y, f x = y) (f x) idp) = s g h,
from @eq_of_is_contr (Π x, Σ y, f x = y) t2 _ _,
have t4 : r (λ x, sigma.mk (f x) idp) = r (s g h),
from ap r t3,
have endt : sigma.mk f (homotopy.refl f) = sigma.mk g h,
from t4,
endt
)
)
local attribute is_contr_sigma_homotopy [instance]
parameters (Q : Π g (h : f ~ g), Type) (d : Q f (homotopy.refl f))
definition homotopy_ind (g : Πx, B x) (h : f ~ g) : Q g h :=
@transport _ (λ gh, Q (pr1 gh) (pr2 gh)) (sigma.mk f (homotopy.refl f)) (sigma.mk g h)
(@eq_of_is_contr _ is_contr_sigma_homotopy _ _) d
local attribute weak_funext [reducible]
local attribute homotopy_ind [reducible]
definition homotopy_ind_comp : homotopy_ind f (homotopy.refl f) = d :=
(@hprop_eq_of_is_contr _ _ _ _ !eq_of_is_contr idp)⁻¹ ▸ idp
end
/- Now the proof is fairly easy; we can just use the same induction principle on both sides. -/
section
universe variables l k
local attribute weak_funext [reducible]
theorem funext_of_weak_funext (wf : weak_funext.{l k}) : funext.{l k} :=
λ A B f g,
let eq_to_f := (λ g' x, f = g') in
let sim2path := homotopy_ind f eq_to_f idp in
assert t1 : sim2path f (homotopy.refl f) = idp,
proof homotopy_ind_comp f eq_to_f idp qed,
assert t2 : apd10 (sim2path f (homotopy.refl f)) = (homotopy.refl f),
proof ap apd10 t1 qed,
have left_inv : apd10 ∘ (sim2path g) ~ id,
proof (homotopy_ind f (λ g' x, apd10 (sim2path g' x) = x) t2) g qed,
have right_inv : (sim2path g) ∘ apd10 ~ id,
from (λ h, eq.rec_on h (homotopy_ind_comp f _ idp)),
is_equiv.adjointify apd10 (sim2path g) left_inv right_inv
definition funext_from_naive_funext : naive_funext → funext :=
compose funext_of_weak_funext weak_funext_of_naive_funext
end
section
universe variables l
private theorem ua_isequiv_postcompose {A B : Type.{l}} {C : Type}
{w : A → B} [H0 : is_equiv w] : is_equiv (@compose C A B w) :=
let w' := equiv.mk w H0 in
let eqinv : A = B := ((@is_equiv.inv _ _ _ (univalence A B)) w') in
let eq' := equiv_of_eq eqinv in
is_equiv.adjointify (@compose C A B w)
(@compose C B A (is_equiv.inv w))
(λ (x : C → B),
have eqretr : eq' = w',
from (@right_inv _ _ (@equiv_of_eq A B) (univalence A B) w'),
have invs_eq : (to_fun eq')⁻¹ = (to_fun w')⁻¹,
from inv_eq eq' w' eqretr,
have eqfin : (to_fun eq') ∘ ((to_fun eq')⁻¹ ∘ x) = x,
from (λ p,
(@eq.rec_on Type.{l} A
(λ B' p', Π (x' : C → B'), (to_fun (equiv_of_eq p'))
∘ ((to_fun (equiv_of_eq p'))⁻¹ ∘ x') = x')
B p (λ x', idp))
) eqinv x,
have eqfin' : (to_fun w') ∘ ((to_fun eq')⁻¹ ∘ x) = x,
from eqretr ▸ eqfin,
have eqfin'' : (to_fun w') ∘ ((to_fun w')⁻¹ ∘ x) = x,
from invs_eq ▸ eqfin',
eqfin''
)
(λ (x : C → A),
have eqretr : eq' = w',
from (@right_inv _ _ (@equiv_of_eq A B) (univalence A B) w'),
have invs_eq : (to_fun eq')⁻¹ = (to_fun w')⁻¹,
from inv_eq eq' w' eqretr,
have eqfin : (to_fun eq')⁻¹ ∘ ((to_fun eq') ∘ x) = x,
from (λ p, eq.rec_on p idp) eqinv,
have eqfin' : (to_fun eq')⁻¹ ∘ ((to_fun w') ∘ x) = x,
from eqretr ▸ eqfin,
have eqfin'' : (to_fun w')⁻¹ ∘ ((to_fun w') ∘ x) = x,
from invs_eq ▸ eqfin',
eqfin''
)
-- We are ready to prove functional extensionality,
-- starting with the naive non-dependent version.
private definition diagonal [reducible] (B : Type) : Type
:= Σ xy : B × B, pr₁ xy = pr₂ xy
private definition isequiv_src_compose {A B : Type}
: @is_equiv (A → diagonal B)
(A → B)
(compose (pr₁ ∘ pr1)) :=
@ua_isequiv_postcompose _ _ _ (pr₁ ∘ pr1)
(is_equiv.adjointify (pr₁ ∘ pr1)
(λ x, sigma.mk (x , x) idp) (λx, idp)
(λ x, sigma.rec_on x
(λ xy, prod.rec_on xy
(λ b c p, eq.rec_on p idp))))
private definition isequiv_tgt_compose {A B : Type}
: is_equiv (compose (pr₂ ∘ pr1) : (A → diagonal B) → (A → B)) :=
begin
refine @ua_isequiv_postcompose _ _ _ (pr2 ∘ pr1) _,
fapply adjointify,
{ intro b, exact ⟨(b, b), idp⟩},
{ intro b, reflexivity},
{ intro a, induction a with q p, induction q, esimp at *, induction p, reflexivity}
end
set_option class.conservative false
theorem nondep_funext_from_ua {A : Type} {B : Type}
: Π {f g : A → B}, f ~ g → f = g :=
(λ (f g : A → B) (p : f ~ g),
let d := λ (x : A), sigma.mk (f x , f x) idp in
let e := λ (x : A), sigma.mk (f x , g x) (p x) in
let precomp1 := compose (pr₁ ∘ pr1) in
have equiv1 [visible] : is_equiv precomp1,
from @isequiv_src_compose A B,
have equiv2 [visible] : Π x y, is_equiv (ap precomp1),
from is_equiv.is_equiv_ap precomp1,
have H' : Π (x y : A → diagonal B),
pr₁ ∘ pr1 ∘ x = pr₁ ∘ pr1 ∘ y → x = y,
from (λ x y, is_equiv.inv (ap precomp1)),
have eq2 : pr₁ ∘ pr1 ∘ d = pr₁ ∘ pr1 ∘ e,
from idp,
have eq0 : d = e,
from H' d e eq2,
have eq1 : (pr₂ ∘ pr1) ∘ d = (pr₂ ∘ pr1) ∘ e,
from ap _ eq0,
eq1
)
end
-- Now we use this to prove weak funext, which as we know
-- implies (with dependent eta) also the strong dependent funext.
theorem weak_funext_of_ua : weak_funext :=
(λ (A : Type) (P : A → Type) allcontr,
let U := (λ (x : A), lift unit) in
have pequiv : Π (x : A), P x ≃ unit,
from (λ x, @equiv_unit_of_is_contr (P x) (allcontr x)),
have psim : Π (x : A), P x = U x,
from (λ x, eq_of_equiv_lift (pequiv x)),
have p : P = U,
from @nondep_funext_from_ua A Type P U psim,
have tU' : is_contr (A → lift unit),
from is_contr.mk (λ x, up ⋆)
(λ f, nondep_funext_from_ua (λa, by induction (f a) with u;induction u;reflexivity)),
have tU : is_contr (Π x, U x),
from tU',
have tlast : is_contr (Πx, P x),
from p⁻¹ ▸ tU,
tlast)
-- In the following we will proof function extensionality using the univalence axiom
definition funext_of_ua : funext :=
funext_of_weak_funext (@weak_funext_of_ua)
variables {A : Type} {P : A → Type} {f g : Π x, P x}
namespace funext
theorem is_equiv_apd [instance] (f g : Π x, P x) : is_equiv (@apd10 A P f g) :=
funext_of_ua f g
end funext
open funext
definition eq_equiv_homotopy : (f = g) ≃ (f ~ g) :=
equiv.mk apd10 _
definition eq_of_homotopy [reducible] : f ~ g → f = g :=
(@apd10 A P f g)⁻¹
definition apd10_eq_of_homotopy (p : f ~ g) : apd10 (eq_of_homotopy p) = p :=
right_inv apd10 p
definition eq_of_homotopy_apd10 (p : f = g) : eq_of_homotopy (apd10 p) = p :=
left_inv apd10 p
definition eq_of_homotopy_idp (f : Π x, P x) : eq_of_homotopy (λx : A, idpath (f x)) = idpath f :=
is_equiv.left_inv apd10 idp
definition naive_funext_of_ua : naive_funext :=
λ A P f g h, eq_of_homotopy h
protected definition homotopy.rec_on [recursor] {Q : (f ~ g) → Type} (p : f ~ g)
(H : Π(q : f = g), Q (apd10 q)) : Q p :=
right_inv apd10 p ▸ H (eq_of_homotopy p)
protected definition homotopy.rec_on_idp [recursor] {Q : Π{g}, (f ~ g) → Type} {g : Π x, P x} (p : f ~ g) (H : Q (homotopy.refl f)) : Q p :=
homotopy.rec_on p (λq, eq.rec_on q H)
definition eq_of_homotopy_inv {f g : Π x, P x} (H : f ~ g)
: eq_of_homotopy (λx, (H x)⁻¹) = (eq_of_homotopy H)⁻¹ :=
begin
apply homotopy.rec_on_idp H,
rewrite [+eq_of_homotopy_idp]
end
definition eq_of_homotopy_con {f g h : Π x, P x} (H1 : f ~ g) (H2 : g ~ h)
: eq_of_homotopy (λx, H1 x ⬝ H2 x) = eq_of_homotopy H1 ⬝ eq_of_homotopy H2 :=
begin
apply homotopy.rec_on_idp H1,
apply homotopy.rec_on_idp H2,
rewrite [+eq_of_homotopy_idp]
end
|
f820b7b937e9d2fedec2e16f32d89aa35d130405 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/analysis/convex/stone_separation.lean | 905b8e6ea26f44d1a48aa5a40e316251814c554e | [
"Apache-2.0"
] | permissive | jcommelin/mathlib | d8456447c36c176e14d96d9e76f39841f69d2d9b | ee8279351a2e434c2852345c51b728d22af5a156 | refs/heads/master | 1,664,782,136,488 | 1,663,638,983,000 | 1,663,638,983,000 | 132,563,656 | 0 | 0 | Apache-2.0 | 1,663,599,929,000 | 1,525,760,539,000 | Lean | UTF-8 | Lean | false | false | 5,086 | lean | /-
Copyright (c) 2022 Yaël Dillies. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies
-/
import analysis.convex.join
/-!
# Stone's separation theorem
This file prove Stone's separation theorem. This tells us that any two disjoint convex sets can be
separated by a convex set whose complement is also convex.
In locally convex real topological vector spaces, the Hahn-Banach separation theorems provide
stronger statements: one may find a separating hyperplane, instead of merely a convex set whose
complement is convex.
-/
open set
open_locale big_operators
variables {𝕜 E ι : Type*} [linear_ordered_field 𝕜] [add_comm_group E] [module 𝕜 E] {s t : set E}
/-- In a tetrahedron with vertices `x`, `y`, `p`, `q`, any segment `[u, v]` joining the opposite
edges `[x, p]` and `[y, q]` passes through any triangle of vertices `p`, `q`, `z` where
`z ∈ [x, y]`. -/
lemma not_disjoint_segment_convex_hull_triple {p q u v x y z : E}
(hz : z ∈ segment 𝕜 x y) (hu : u ∈ segment 𝕜 x p) (hv : v ∈ segment 𝕜 y q) :
¬ disjoint (segment 𝕜 u v) (convex_hull 𝕜 {p, q, z}) :=
begin
rw not_disjoint_iff,
obtain ⟨az, bz, haz, hbz, habz, rfl⟩ := hz,
obtain rfl | haz' := haz.eq_or_lt,
{ rw zero_add at habz,
rw [zero_smul, zero_add, habz, one_smul],
refine ⟨v, right_mem_segment _ _ _, segment_subset_convex_hull _ _ hv⟩; simp },
obtain ⟨av, bv, hav, hbv, habv, rfl⟩ := hv,
obtain rfl | hav' := hav.eq_or_lt,
{ rw zero_add at habv,
rw [zero_smul, zero_add, habv, one_smul],
exact ⟨q, right_mem_segment _ _ _, subset_convex_hull _ _ $ by simp⟩ },
obtain ⟨au, bu, hau, hbu, habu, rfl⟩ := hu,
have hab : 0 < az * av + bz * au :=
add_pos_of_pos_of_nonneg (mul_pos haz' hav') (mul_nonneg hbz hau),
refine ⟨(az * av / (az * av + bz * au)) • (au • x + bu • p) +
(bz * au / (az * av + bz * au)) • (av • y + bv • q), ⟨_, _, _, _, _, rfl⟩, _⟩,
{ exact div_nonneg (mul_nonneg haz hav) hab.le },
{ exact div_nonneg (mul_nonneg hbz hau) hab.le },
{ rw [←add_div, div_self hab.ne'] },
rw [smul_add, smul_add, add_add_add_comm, add_comm, ←mul_smul, ←mul_smul],
classical,
let w : fin 3 → 𝕜 := ![az * av * bu, bz * au * bv, au * av],
let z : fin 3 → E := ![p, q, az • x + bz • y],
have hw₀ : ∀ i, 0 ≤ w i,
{ rintro i,
fin_cases i,
{ exact mul_nonneg (mul_nonneg haz hav) hbu },
{ exact mul_nonneg (mul_nonneg hbz hau) hbv },
{ exact mul_nonneg hau hav } },
have hw : ∑ i, w i = az * av + bz * au,
{ transitivity az * av * bu + (bz * au * bv + au * av),
{ simp [w, fin.sum_univ_succ, fin.sum_univ_zero] },
rw [←one_mul (au * av), ←habz, add_mul, ←add_assoc, add_add_add_comm, mul_assoc, ←mul_add,
mul_assoc, ←mul_add, mul_comm av, ←add_mul, ←mul_add, add_comm bu, add_comm bv, habu, habv,
one_mul, mul_one] },
have hz : ∀ i, z i ∈ ({p, q, az • x + bz • y} : set E),
{ rintro i,
fin_cases i; simp [z] },
convert finset.center_mass_mem_convex_hull (finset.univ : finset (fin 3)) (λ i _, hw₀ i)
(by rwa hw) (λ i _, hz i),
rw finset.center_mass,
simp_rw [div_eq_inv_mul, hw, mul_assoc, mul_smul (az * av + bz * au)⁻¹, ←smul_add, add_assoc,
←mul_assoc],
congr' 3,
rw [←mul_smul, ←mul_rotate, mul_right_comm, mul_smul, ←mul_smul _ av, mul_rotate, mul_smul _ bz,
←smul_add],
simp only [list.map, list.pmap, nat.add_def, add_zero, fin.mk_bit0,
fin.mk_one, list.foldr_cons, list.foldr_nil],
refl,
end
/-- **Stone's Separation Theorem** -/
lemma exists_convex_convex_compl_subset (hs : convex 𝕜 s) (ht : convex 𝕜 t) (hst : disjoint s t) :
∃ C : set E, convex 𝕜 C ∧ convex 𝕜 Cᶜ ∧ s ⊆ C ∧ t ⊆ Cᶜ :=
begin
let S : set (set E) := {C | convex 𝕜 C ∧ disjoint C t},
obtain ⟨C, hC, hsC, hCmax⟩ := zorn_subset_nonempty S
(λ c hcS hc ⟨t, ht⟩, ⟨⋃₀ c, ⟨hc.directed_on.convex_sUnion (λ s hs, (hcS hs).1),
disjoint_sUnion_left.2 $ λ c hc, (hcS hc).2⟩, λ s, subset_sUnion_of_mem⟩) s ⟨hs, hst⟩,
refine ⟨C, hC.1, convex_iff_segment_subset.2 $ λ x hx y hy z hz hzC, _, hsC,
hC.2.subset_compl_left⟩,
suffices h : ∀ c ∈ Cᶜ, ∃ a ∈ C, (segment 𝕜 c a ∩ t).nonempty,
{ obtain ⟨p, hp, u, hu, hut⟩ := h x hx,
obtain ⟨q, hq, v, hv, hvt⟩ := h y hy,
refine not_disjoint_segment_convex_hull_triple hz hu hv
(hC.2.symm.mono (ht.segment_subset hut hvt) $ convex_hull_min _ hC.1),
simp [insert_subset, hp, hq, singleton_subset_iff.2 hzC] },
rintro c hc,
by_contra' h,
suffices h : disjoint (convex_hull 𝕜 (insert c C)) t,
{ rw ←hCmax _ ⟨convex_convex_hull _ _, h⟩
((subset_insert _ _).trans $ subset_convex_hull _ _) at hc,
exact hc (subset_convex_hull _ _ $ mem_insert _ _) },
rw [convex_hull_insert ⟨z, hzC⟩, convex_join_singleton_left],
refine disjoint_Union₂_left.2 (λ a ha b hb, h a _ ⟨b, hb⟩),
rwa ←hC.1.convex_hull_eq,
end
|
f0865ed64e12eb93a3e2d5066f7fd543e8666d15 | b7f22e51856f4989b970961f794f1c435f9b8f78 | /library/init/wf.lean | a8fd38fbac5aef2718fe7e24ad9f1ee235a72684 | [
"Apache-2.0"
] | permissive | soonhokong/lean | cb8aa01055ffe2af0fb99a16b4cda8463b882cd1 | 38607e3eb57f57f77c0ac114ad169e9e4262e24f | refs/heads/master | 1,611,187,284,081 | 1,450,766,737,000 | 1,476,122,547,000 | 11,513,992 | 2 | 0 | null | 1,401,763,102,000 | 1,374,182,235,000 | C++ | UTF-8 | Lean | false | false | 7,598 | lean | /-
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
-/
prelude
import init.relation init.tactic init.nat init.prod
inductive acc {A : Type} (R : A → A → Prop) : A → Prop :=
intro : ∀x, (∀ y, R y x → acc R y) → acc R x
namespace acc
variables {A : Type} {R : A → A → Prop}
definition inv {x y : A} (H₁ : acc R x) (H₂ : R y x) : acc R y :=
acc.rec_on H₁ (λ x₁ ac₁ iH H₂, ac₁ y H₂) H₂
-- dependent elimination for acc
protected definition drec [recursor]
{C : Π (a : A), acc R a → Type}
(h₁ : Π (x : A) (acx : Π (y : A), R y x → acc R y),
(Π (y : A) (ryx : R y x), C y (acx y ryx)) → C x (acc.intro x acx))
{a : A} (h₂ : acc R a) : C a h₂ :=
begin
refine acc.rec _ h₂ h₂,
intro x acx ih h₂,
exact h₁ x acx (λ y ryx, ih y ryx (acx y ryx))
end
end acc
inductive well_founded [class] {A : Type} (R : A → A → Prop) : Prop :=
intro : (∀ a, acc R a) → well_founded R
namespace well_founded
definition apply [coercion] {A : Type} {R : A → A → Prop} (wf : well_founded R) : ∀a, acc R a :=
take a, well_founded.rec_on wf (λp, p) a
section
parameters {A : Type} {R : A → A → Prop}
local infix `≺`:50 := R
hypothesis [Hwf : well_founded R]
theorem recursion {C : A → Type} (a : A) (H : Πx, (Πy, y ≺ x → C y) → C x) : C a :=
acc.rec_on (Hwf a) (λ x₁ ac₁ iH, H x₁ iH)
theorem induction {C : A → Prop} (a : A) (H : ∀x, (∀y, y ≺ x → C y) → C x) : C a :=
recursion a H
variable {C : A → Type}
variable F : Πx, (Πy, y ≺ x → C y) → C x
definition fix_F (x : A) (a : acc R x) : C x :=
acc.rec_on a (λ x₁ ac₁ iH, F x₁ iH)
theorem fix_F_eq (x : A) (r : acc R x) :
fix_F F x r = F x (λ (y : A) (p : y ≺ x), fix_F F y (acc.inv r p)) :=
begin
induction r using acc.drec,
reflexivity -- proof is trivial due to proof irrelevance
end
end
variables {A : Type} {C : A → Type} {R : A → A → Prop}
-- Well-founded fixpoint
definition fix [Hwf : well_founded R] (F : Πx, (Πy, R y x → C y) → C x) (x : A) : C x :=
fix_F F x (Hwf x)
-- Well-founded fixpoint satisfies fixpoint equation
theorem fix_eq [Hwf : well_founded R] (F : Πx, (Πy, R y x → C y) → C x) (x : A) :
fix F x = F x (λy h, fix F y) :=
fix_F_eq F x (Hwf x)
end well_founded
open well_founded
-- Empty relation is well-founded
definition empty.wf {A : Type} : well_founded empty_relation :=
well_founded.intro (λ (a : A),
acc.intro a (λ (b : A) (lt : false), false.rec _ lt))
-- Subrelation of a well-founded relation is well-founded
namespace subrelation
section
parameters {A : Type} {R Q : A → A → Prop}
parameters (H₁ : subrelation Q R)
parameters (H₂ : well_founded R)
definition accessible {a : A} (ac : acc R a) : acc Q a :=
using H₁,
begin
induction ac with x ax ih, constructor,
exact λ (y : A) (lt : Q y x), ih y (H₁ lt)
end
definition wf : well_founded Q :=
well_founded.intro (λ a, accessible (H₂ a))
end
end subrelation
-- The inverse image of a well-founded relation is well-founded
namespace inv_image
section
parameters {A B : Type} {R : B → B → Prop}
parameters (f : A → B)
parameters (H : well_founded R)
private definition acc_aux {b : B} (ac : acc R b) : ∀ x, f x = b → acc (inv_image R f) x :=
begin
induction ac with x acx ih,
intro z e, constructor,
intro y lt, subst x,
exact ih (f y) lt y rfl
end
definition accessible {a : A} (ac : acc R (f a)) : acc (inv_image R f) a :=
acc_aux ac a rfl
definition wf : well_founded (inv_image R f) :=
well_founded.intro (λ a, accessible (H (f a)))
end
end inv_image
-- The transitive closure of a well-founded relation is well-founded
namespace tc
section
parameters {A : Type} {R : A → A → Prop}
local notation `R⁺` := tc R
definition accessible {z} (ac: acc R z) : acc R⁺ z :=
begin
induction ac with x acx ih,
constructor, intro y rel,
induction rel with a b rab a b c rab rbc ih₁ ih₂,
{exact ih a rab},
{exact acc.inv (ih₂ acx ih) rab}
end
definition wf (H : well_founded R) : well_founded R⁺ :=
well_founded.intro (λ a, accessible (H a))
end
end tc
namespace nat
-- less-than is well-founded
definition lt.wf [instance] : well_founded lt :=
well_founded.intro (nat.rec
(!acc.intro (λn H, absurd H (not_lt_zero n)))
(λn IH, !acc.intro (λm H,
or.elim (nat.eq_or_lt_of_le (le_of_succ_le_succ H))
(λe, eq.substr e IH) (acc.inv IH))))
definition measure {A : Type} : (A → ℕ) → A → A → Prop :=
inv_image lt
definition measure.wf {A : Type} (f : A → ℕ) : well_founded (measure f) :=
inv_image.wf f lt.wf
end nat
namespace prod
open well_founded
section
variables {A B : Type}
variable (Ra : A → A → Prop)
variable (Rb : B → B → Prop)
-- Lexicographical order based on Ra and Rb
inductive lex : A × B → A × B → Prop :=
| left : ∀{a₁ b₁} a₂ b₂, Ra a₁ a₂ → lex (a₁, b₁) (a₂, b₂)
| right : ∀a {b₁ b₂}, Rb b₁ b₂ → lex (a, b₁) (a, b₂)
-- Relational product based on Ra and Rb
inductive rprod : A × B → A × B → Prop :=
intro : ∀{a₁ b₁ a₂ b₂}, Ra a₁ a₂ → Rb b₁ b₂ → rprod (a₁, b₁) (a₂, b₂)
end
section
parameters {A B : Type}
parameters {Ra : A → A → Prop} {Rb : B → B → Prop}
local infix `≺`:50 := lex Ra Rb
definition lex.accessible {a} (aca : acc Ra a) (acb : ∀b, acc Rb b): ∀b, acc (lex Ra Rb) (a, b) :=
acc.rec_on aca
(λxa aca (iHa : ∀y, Ra y xa → ∀b, acc (lex Ra Rb) (y, b)),
λb, acc.rec_on (acb b)
(λxb acb
(iHb : ∀y, Rb y xb → acc (lex Ra Rb) (xa, y)),
acc.intro (xa, xb) (λp (lt : p ≺ (xa, xb)),
have aux : xa = xa → xb = xb → acc (lex Ra Rb) p, from
@prod.lex.rec_on A B Ra Rb (λp₁ p₂, pr₁ p₂ = xa → pr₂ p₂ = xb → acc (lex Ra Rb) p₁)
p (xa, xb) lt
(λa₁ b₁ a₂ b₂ (H : Ra a₁ a₂) (eq₂ : a₂ = xa) (eq₃ : b₂ = xb),
show acc (lex Ra Rb) (a₁, b₁), from
have Ra₁ : Ra a₁ xa, from eq.rec_on eq₂ H,
iHa a₁ Ra₁ b₁)
(λa b₁ b₂ (H : Rb b₁ b₂) (eq₂ : a = xa) (eq₃ : b₂ = xb),
show acc (lex Ra Rb) (a, b₁), from
have Rb₁ : Rb b₁ xb, from eq.rec_on eq₃ H,
have eq₂' : xa = a, from eq.rec_on eq₂ rfl,
eq.rec_on eq₂' (iHb b₁ Rb₁)),
aux rfl rfl)))
-- The lexicographical order of well founded relations is well-founded
definition lex.wf (Ha : well_founded Ra) (Hb : well_founded Rb) : well_founded (lex Ra Rb) :=
well_founded.intro (λp, destruct p (λa b, lex.accessible (Ha a) (well_founded.apply Hb) b))
-- Relational product is a subrelation of the lex
definition rprod.sub_lex : ∀ a b, rprod Ra Rb a b → lex Ra Rb a b :=
λa b H, prod.rprod.rec_on H (λ a₁ b₁ a₂ b₂ H₁ H₂, lex.left Rb a₂ b₂ H₁)
-- The relational product of well founded relations is well-founded
definition rprod.wf (Ha : well_founded Ra) (Hb : well_founded Rb) : well_founded (rprod Ra Rb) :=
subrelation.wf (rprod.sub_lex) (lex.wf Ha Hb)
end
end prod
|
0948ec3cb64f92a55430909344ac8fdbf6953a57 | 82b86ba2ae0d5aed0f01f49c46db5afec0eb2bd7 | /src/Lean/Elab/Exception.lean | 5cb9d1fc24b0b396694bce1b85f860b2dcdcf220 | [
"Apache-2.0"
] | permissive | banksonian/lean4 | 3a2e6b0f1eb63aa56ff95b8d07b2f851072d54dc | 78da6b3aa2840693eea354a41e89fc5b212a5011 | refs/heads/master | 1,673,703,624,165 | 1,605,123,551,000 | 1,605,123,551,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 1,624 | lean | /-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
import Lean.InternalExceptionId
import Lean.Meta.Basic
namespace Lean.Elab
builtin_initialize postponeExceptionId : InternalExceptionId ← registerInternalExceptionId `postpone
builtin_initialize unsupportedSyntaxExceptionId : InternalExceptionId ← registerInternalExceptionId `unsupportedSyntax
builtin_initialize abortExceptionId : InternalExceptionId ← registerInternalExceptionId `abortElab
def throwPostpone {α m} [MonadExceptOf Exception m] : m α :=
throw $ Exception.internal postponeExceptionId
def throwUnsupportedSyntax {α m} [MonadExceptOf Exception m] : m α :=
throw $ Exception.internal unsupportedSyntaxExceptionId
def throwIllFormedSyntax {α m} [Monad m] [MonadExceptOf Exception m] [Ref m] [AddErrorMessageContext m] : m α :=
throwError "ill-formed syntax"
def throwAlreadyDeclaredUniverseLevel {α m} [Monad m] [MonadExceptOf Exception m] [Ref m] [AddErrorMessageContext m] (u : Name) : m α :=
throwError! "a universe level named '{u}' has already been declared"
-- Throw exception to abort elaboration without producing any error message
def throwAbort {α m} [MonadExcept Exception m] : m α :=
throw $ Exception.internal abortExceptionId
def mkMessageCore (fileName : String) (fileMap : FileMap) (msgData : MessageData) (severity : MessageSeverity) (pos : String.Pos) : Message :=
let pos := fileMap.toPosition pos
{ fileName := fileName, pos := pos, data := msgData, severity := severity }
end Lean.Elab
|
fe92b559afc1816c3a1a250811cbdf7bb56c8606 | 94e33a31faa76775069b071adea97e86e218a8ee | /src/analysis/special_functions/trigonometric/basic.lean | 9696d63e56795e6a2f866cc3f987e8ef5d33655a | [
"Apache-2.0"
] | permissive | urkud/mathlib | eab80095e1b9f1513bfb7f25b4fa82fa4fd02989 | 6379d39e6b5b279df9715f8011369a301b634e41 | refs/heads/master | 1,658,425,342,662 | 1,658,078,703,000 | 1,658,078,703,000 | 186,910,338 | 0 | 0 | Apache-2.0 | 1,568,512,083,000 | 1,557,958,709,000 | Lean | UTF-8 | Lean | false | false | 41,474 | lean | /-
Copyright (c) 2018 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes, Abhimanyu Pallavi Sudhir, Jean Lo, Calle Sönne, Benjamin Davidson
-/
import analysis.special_functions.exp
import data.set.intervals.infinite
/-!
# Trigonometric functions
## Main definitions
This file contains the definition of `π`.
See also `analysis.special_functions.trigonometric.inverse` and
`analysis.special_functions.trigonometric.arctan` for the inverse trigonometric functions.
See also `analysis.special_functions.complex.arg` and
`analysis.special_functions.complex.log` for the complex argument function
and the complex logarithm.
## Main statements
Many basic inequalities on the real trigonometric functions are established.
The continuity of the usual trigonometric functions is proved.
Several facts about the real trigonometric functions have the proofs deferred to
`analysis.special_functions.trigonometric.complex`,
as they are most easily proved by appealing to the corresponding fact for
complex trigonometric functions.
See also `analysis.special_functions.trigonometric.chebyshev` for the multiple angle formulas
in terms of Chebyshev polynomials.
## Tags
sin, cos, tan, angle
-/
noncomputable theory
open_locale classical topological_space filter
open set filter
namespace complex
@[continuity] lemma continuous_sin : continuous sin :=
by { change continuous (λ z, ((exp (-z * I) - exp (z * I)) * I) / 2), continuity, }
lemma continuous_on_sin {s : set ℂ} : continuous_on sin s := continuous_sin.continuous_on
@[continuity] lemma continuous_cos : continuous cos :=
by { change continuous (λ z, (exp (z * I) + exp (-z * I)) / 2), continuity, }
lemma continuous_on_cos {s : set ℂ} : continuous_on cos s := continuous_cos.continuous_on
@[continuity] lemma continuous_sinh : continuous sinh :=
by { change continuous (λ z, (exp z - exp (-z)) / 2), continuity, }
@[continuity] lemma continuous_cosh : continuous cosh :=
by { change continuous (λ z, (exp z + exp (-z)) / 2), continuity, }
end complex
namespace real
variables {x y z : ℝ}
@[continuity] lemma continuous_sin : continuous sin :=
complex.continuous_re.comp (complex.continuous_sin.comp complex.continuous_of_real)
lemma continuous_on_sin {s} : continuous_on sin s :=
continuous_sin.continuous_on
@[continuity] lemma continuous_cos : continuous cos :=
complex.continuous_re.comp (complex.continuous_cos.comp complex.continuous_of_real)
lemma continuous_on_cos {s} : continuous_on cos s := continuous_cos.continuous_on
@[continuity] lemma continuous_sinh : continuous sinh :=
complex.continuous_re.comp (complex.continuous_sinh.comp complex.continuous_of_real)
@[continuity] lemma continuous_cosh : continuous cosh :=
complex.continuous_re.comp (complex.continuous_cosh.comp complex.continuous_of_real)
end real
namespace real
lemma exists_cos_eq_zero : 0 ∈ cos '' Icc (1:ℝ) 2 :=
intermediate_value_Icc' (by norm_num) continuous_on_cos
⟨le_of_lt cos_two_neg, le_of_lt cos_one_pos⟩
/-- The number π = 3.14159265... Defined here using choice as twice a zero of cos in [1,2], from
which one can derive all its properties. For explicit bounds on π, see `data.real.pi.bounds`. -/
protected noncomputable def pi : ℝ := 2 * classical.some exists_cos_eq_zero
localized "notation `π` := real.pi" in real
@[simp] lemma cos_pi_div_two : cos (π / 2) = 0 :=
by rw [real.pi, mul_div_cancel_left _ (@two_ne_zero' ℝ _ _)];
exact (classical.some_spec exists_cos_eq_zero).2
lemma one_le_pi_div_two : (1 : ℝ) ≤ π / 2 :=
by rw [real.pi, mul_div_cancel_left _ (@two_ne_zero' ℝ _ _)];
exact (classical.some_spec exists_cos_eq_zero).1.1
lemma pi_div_two_le_two : π / 2 ≤ 2 :=
by rw [real.pi, mul_div_cancel_left _ (@two_ne_zero' ℝ _ _)];
exact (classical.some_spec exists_cos_eq_zero).1.2
lemma two_le_pi : (2 : ℝ) ≤ π :=
(div_le_div_right (show (0 : ℝ) < 2, by norm_num)).1
(by rw div_self (@two_ne_zero' ℝ _ _); exact one_le_pi_div_two)
lemma pi_le_four : π ≤ 4 :=
(div_le_div_right (show (0 : ℝ) < 2, by norm_num)).1
(calc π / 2 ≤ 2 : pi_div_two_le_two
... = 4 / 2 : by norm_num)
lemma pi_pos : 0 < π :=
lt_of_lt_of_le (by norm_num) two_le_pi
lemma pi_ne_zero : π ≠ 0 :=
ne_of_gt pi_pos
lemma pi_div_two_pos : 0 < π / 2 :=
half_pos pi_pos
lemma two_pi_pos : 0 < 2 * π :=
by linarith [pi_pos]
end real
namespace nnreal
open real
open_locale real nnreal
/-- `π` considered as a nonnegative real. -/
noncomputable def pi : ℝ≥0 := ⟨π, real.pi_pos.le⟩
@[simp] lemma coe_real_pi : (pi : ℝ) = π := rfl
lemma pi_pos : 0 < pi := by exact_mod_cast real.pi_pos
lemma pi_ne_zero : pi ≠ 0 := pi_pos.ne'
end nnreal
namespace real
open_locale real
@[simp] lemma sin_pi : sin π = 0 :=
by rw [← mul_div_cancel_left π (@two_ne_zero ℝ _ _), two_mul, add_div,
sin_add, cos_pi_div_two]; simp
@[simp] lemma cos_pi : cos π = -1 :=
by rw [← mul_div_cancel_left π (@two_ne_zero ℝ _ _), mul_div_assoc,
cos_two_mul, cos_pi_div_two];
simp [bit0, pow_add]
@[simp] lemma sin_two_pi : sin (2 * π) = 0 :=
by simp [two_mul, sin_add]
@[simp] lemma cos_two_pi : cos (2 * π) = 1 :=
by simp [two_mul, cos_add]
lemma sin_antiperiodic : function.antiperiodic sin π :=
by simp [sin_add]
lemma sin_periodic : function.periodic sin (2 * π) :=
sin_antiperiodic.periodic
@[simp] lemma sin_add_pi (x : ℝ) : sin (x + π) = -sin x :=
sin_antiperiodic x
@[simp] lemma sin_add_two_pi (x : ℝ) : sin (x + 2 * π) = sin x :=
sin_periodic x
@[simp] lemma sin_sub_pi (x : ℝ) : sin (x - π) = -sin x :=
sin_antiperiodic.sub_eq x
@[simp] lemma sin_sub_two_pi (x : ℝ) : sin (x - 2 * π) = sin x :=
sin_periodic.sub_eq x
@[simp] lemma sin_pi_sub (x : ℝ) : sin (π - x) = sin x :=
neg_neg (sin x) ▸ sin_neg x ▸ sin_antiperiodic.sub_eq'
@[simp] lemma sin_two_pi_sub (x : ℝ) : sin (2 * π - x) = -sin x :=
sin_neg x ▸ sin_periodic.sub_eq'
@[simp] lemma sin_nat_mul_pi (n : ℕ) : sin (n * π) = 0 :=
sin_antiperiodic.nat_mul_eq_of_eq_zero sin_zero n
@[simp] lemma sin_int_mul_pi (n : ℤ) : sin (n * π) = 0 :=
sin_antiperiodic.int_mul_eq_of_eq_zero sin_zero n
@[simp] lemma sin_add_nat_mul_two_pi (x : ℝ) (n : ℕ) : sin (x + n * (2 * π)) = sin x :=
sin_periodic.nat_mul n x
@[simp] lemma sin_add_int_mul_two_pi (x : ℝ) (n : ℤ) : sin (x + n * (2 * π)) = sin x :=
sin_periodic.int_mul n x
@[simp] lemma sin_sub_nat_mul_two_pi (x : ℝ) (n : ℕ) : sin (x - n * (2 * π)) = sin x :=
sin_periodic.sub_nat_mul_eq n
@[simp] lemma sin_sub_int_mul_two_pi (x : ℝ) (n : ℤ) : sin (x - n * (2 * π)) = sin x :=
sin_periodic.sub_int_mul_eq n
@[simp] lemma sin_nat_mul_two_pi_sub (x : ℝ) (n : ℕ) : sin (n * (2 * π) - x) = -sin x :=
sin_neg x ▸ sin_periodic.nat_mul_sub_eq n
@[simp] lemma sin_int_mul_two_pi_sub (x : ℝ) (n : ℤ) : sin (n * (2 * π) - x) = -sin x :=
sin_neg x ▸ sin_periodic.int_mul_sub_eq n
lemma cos_antiperiodic : function.antiperiodic cos π :=
by simp [cos_add]
lemma cos_periodic : function.periodic cos (2 * π) :=
cos_antiperiodic.periodic
@[simp] lemma cos_add_pi (x : ℝ) : cos (x + π) = -cos x :=
cos_antiperiodic x
@[simp] lemma cos_add_two_pi (x : ℝ) : cos (x + 2 * π) = cos x :=
cos_periodic x
@[simp] lemma cos_sub_pi (x : ℝ) : cos (x - π) = -cos x :=
cos_antiperiodic.sub_eq x
@[simp] lemma cos_sub_two_pi (x : ℝ) : cos (x - 2 * π) = cos x :=
cos_periodic.sub_eq x
@[simp] lemma cos_pi_sub (x : ℝ) : cos (π - x) = -cos x :=
cos_neg x ▸ cos_antiperiodic.sub_eq'
@[simp] lemma cos_two_pi_sub (x : ℝ) : cos (2 * π - x) = cos x :=
cos_neg x ▸ cos_periodic.sub_eq'
@[simp] lemma cos_nat_mul_two_pi (n : ℕ) : cos (n * (2 * π)) = 1 :=
(cos_periodic.nat_mul_eq n).trans cos_zero
@[simp] lemma cos_int_mul_two_pi (n : ℤ) : cos (n * (2 * π)) = 1 :=
(cos_periodic.int_mul_eq n).trans cos_zero
@[simp] lemma cos_add_nat_mul_two_pi (x : ℝ) (n : ℕ) : cos (x + n * (2 * π)) = cos x :=
cos_periodic.nat_mul n x
@[simp] lemma cos_add_int_mul_two_pi (x : ℝ) (n : ℤ) : cos (x + n * (2 * π)) = cos x :=
cos_periodic.int_mul n x
@[simp] lemma cos_sub_nat_mul_two_pi (x : ℝ) (n : ℕ) : cos (x - n * (2 * π)) = cos x :=
cos_periodic.sub_nat_mul_eq n
@[simp] lemma cos_sub_int_mul_two_pi (x : ℝ) (n : ℤ) : cos (x - n * (2 * π)) = cos x :=
cos_periodic.sub_int_mul_eq n
@[simp] lemma cos_nat_mul_two_pi_sub (x : ℝ) (n : ℕ) : cos (n * (2 * π) - x) = cos x :=
cos_neg x ▸ cos_periodic.nat_mul_sub_eq n
@[simp] lemma cos_int_mul_two_pi_sub (x : ℝ) (n : ℤ) : cos (n * (2 * π) - x) = cos x :=
cos_neg x ▸ cos_periodic.int_mul_sub_eq n
@[simp] lemma cos_nat_mul_two_pi_add_pi (n : ℕ) : cos (n * (2 * π) + π) = -1 :=
by simpa only [cos_zero] using (cos_periodic.nat_mul n).add_antiperiod_eq cos_antiperiodic
@[simp] lemma cos_int_mul_two_pi_add_pi (n : ℤ) : cos (n * (2 * π) + π) = -1 :=
by simpa only [cos_zero] using (cos_periodic.int_mul n).add_antiperiod_eq cos_antiperiodic
@[simp] lemma cos_nat_mul_two_pi_sub_pi (n : ℕ) : cos (n * (2 * π) - π) = -1 :=
by simpa only [cos_zero] using (cos_periodic.nat_mul n).sub_antiperiod_eq cos_antiperiodic
@[simp] lemma cos_int_mul_two_pi_sub_pi (n : ℤ) : cos (n * (2 * π) - π) = -1 :=
by simpa only [cos_zero] using (cos_periodic.int_mul n).sub_antiperiod_eq cos_antiperiodic
lemma sin_pos_of_pos_of_lt_pi {x : ℝ} (h0x : 0 < x) (hxp : x < π) : 0 < sin x :=
if hx2 : x ≤ 2 then sin_pos_of_pos_of_le_two h0x hx2
else
have (2 : ℝ) + 2 = 4, from rfl,
have π - x ≤ 2, from sub_le_iff_le_add.2
(le_trans pi_le_four (this ▸ add_le_add_left (le_of_not_ge hx2) _)),
sin_pi_sub x ▸ sin_pos_of_pos_of_le_two (sub_pos.2 hxp) this
lemma sin_pos_of_mem_Ioo {x : ℝ} (hx : x ∈ Ioo 0 π) : 0 < sin x :=
sin_pos_of_pos_of_lt_pi hx.1 hx.2
lemma sin_nonneg_of_mem_Icc {x : ℝ} (hx : x ∈ Icc 0 π) : 0 ≤ sin x :=
begin
rw ← closure_Ioo pi_ne_zero.symm at hx,
exact closure_lt_subset_le continuous_const continuous_sin
(closure_mono (λ y, sin_pos_of_mem_Ioo) hx)
end
lemma sin_nonneg_of_nonneg_of_le_pi {x : ℝ} (h0x : 0 ≤ x) (hxp : x ≤ π) : 0 ≤ sin x :=
sin_nonneg_of_mem_Icc ⟨h0x, hxp⟩
lemma sin_neg_of_neg_of_neg_pi_lt {x : ℝ} (hx0 : x < 0) (hpx : -π < x) : sin x < 0 :=
neg_pos.1 $ sin_neg x ▸ sin_pos_of_pos_of_lt_pi (neg_pos.2 hx0) (neg_lt.1 hpx)
lemma sin_nonpos_of_nonnpos_of_neg_pi_le {x : ℝ} (hx0 : x ≤ 0) (hpx : -π ≤ x) : sin x ≤ 0 :=
neg_nonneg.1 $ sin_neg x ▸ sin_nonneg_of_nonneg_of_le_pi (neg_nonneg.2 hx0) (neg_le.1 hpx)
@[simp] lemma sin_pi_div_two : sin (π / 2) = 1 :=
have sin (π / 2) = 1 ∨ sin (π / 2) = -1 :=
by simpa [sq, mul_self_eq_one_iff] using sin_sq_add_cos_sq (π / 2),
this.resolve_right
(λ h, (show ¬(0 : ℝ) < -1, by norm_num) $
h ▸ sin_pos_of_pos_of_lt_pi pi_div_two_pos (half_lt_self pi_pos))
lemma sin_add_pi_div_two (x : ℝ) : sin (x + π / 2) = cos x :=
by simp [sin_add]
lemma sin_sub_pi_div_two (x : ℝ) : sin (x - π / 2) = -cos x :=
by simp [sub_eq_add_neg, sin_add]
lemma sin_pi_div_two_sub (x : ℝ) : sin (π / 2 - x) = cos x :=
by simp [sub_eq_add_neg, sin_add]
lemma cos_add_pi_div_two (x : ℝ) : cos (x + π / 2) = -sin x :=
by simp [cos_add]
lemma cos_sub_pi_div_two (x : ℝ) : cos (x - π / 2) = sin x :=
by simp [sub_eq_add_neg, cos_add]
lemma cos_pi_div_two_sub (x : ℝ) : cos (π / 2 - x) = sin x :=
by rw [← cos_neg, neg_sub, cos_sub_pi_div_two]
lemma cos_pos_of_mem_Ioo {x : ℝ} (hx : x ∈ Ioo (-(π / 2)) (π / 2)) : 0 < cos x :=
sin_add_pi_div_two x ▸ sin_pos_of_mem_Ioo ⟨by linarith [hx.1], by linarith [hx.2]⟩
lemma cos_nonneg_of_mem_Icc {x : ℝ} (hx : x ∈ Icc (-(π / 2)) (π / 2)) : 0 ≤ cos x :=
sin_add_pi_div_two x ▸ sin_nonneg_of_mem_Icc ⟨by linarith [hx.1], by linarith [hx.2]⟩
lemma cos_nonneg_of_neg_pi_div_two_le_of_le {x : ℝ} (hl : -(π / 2) ≤ x) (hu : x ≤ π / 2) :
0 ≤ cos x :=
cos_nonneg_of_mem_Icc ⟨hl, hu⟩
lemma cos_neg_of_pi_div_two_lt_of_lt {x : ℝ} (hx₁ : π / 2 < x) (hx₂ : x < π + π / 2) : cos x < 0 :=
neg_pos.1 $ cos_pi_sub x ▸ cos_pos_of_mem_Ioo ⟨by linarith, by linarith⟩
lemma cos_nonpos_of_pi_div_two_le_of_le {x : ℝ} (hx₁ : π / 2 ≤ x) (hx₂ : x ≤ π + π / 2) :
cos x ≤ 0 :=
neg_nonneg.1 $ cos_pi_sub x ▸ cos_nonneg_of_mem_Icc ⟨by linarith, by linarith⟩
lemma sin_eq_sqrt_one_sub_cos_sq {x : ℝ} (hl : 0 ≤ x) (hu : x ≤ π) :
sin x = sqrt (1 - cos x ^ 2) :=
by rw [← abs_sin_eq_sqrt_one_sub_cos_sq, abs_of_nonneg (sin_nonneg_of_nonneg_of_le_pi hl hu)]
lemma cos_eq_sqrt_one_sub_sin_sq {x : ℝ} (hl : -(π / 2) ≤ x) (hu : x ≤ π / 2) :
cos x = sqrt (1 - sin x ^ 2) :=
by rw [← abs_cos_eq_sqrt_one_sub_sin_sq, abs_of_nonneg (cos_nonneg_of_mem_Icc ⟨hl, hu⟩)]
lemma sin_eq_zero_iff_of_lt_of_lt {x : ℝ} (hx₁ : -π < x) (hx₂ : x < π) :
sin x = 0 ↔ x = 0 :=
⟨λ h, le_antisymm
(le_of_not_gt (λ h0, lt_irrefl (0 : ℝ) $
calc 0 < sin x : sin_pos_of_pos_of_lt_pi h0 hx₂
... = 0 : h))
(le_of_not_gt (λ h0, lt_irrefl (0 : ℝ) $
calc 0 = sin x : h.symm
... < 0 : sin_neg_of_neg_of_neg_pi_lt h0 hx₁)),
λ h, by simp [h]⟩
lemma sin_eq_zero_iff {x : ℝ} : sin x = 0 ↔ ∃ n : ℤ, (n : ℝ) * π = x :=
⟨λ h, ⟨⌊x / π⌋, le_antisymm (sub_nonneg.1 (int.sub_floor_div_mul_nonneg _ pi_pos))
(sub_nonpos.1 $ le_of_not_gt $ λ h₃,
(sin_pos_of_pos_of_lt_pi h₃ (int.sub_floor_div_mul_lt _ pi_pos)).ne
(by simp [sub_eq_add_neg, sin_add, h, sin_int_mul_pi]))⟩,
λ ⟨n, hn⟩, hn ▸ sin_int_mul_pi _⟩
lemma sin_ne_zero_iff {x : ℝ} : sin x ≠ 0 ↔ ∀ n : ℤ, (n : ℝ) * π ≠ x :=
by rw [← not_exists, not_iff_not, sin_eq_zero_iff]
lemma sin_eq_zero_iff_cos_eq {x : ℝ} : sin x = 0 ↔ cos x = 1 ∨ cos x = -1 :=
by rw [← mul_self_eq_one_iff, ← sin_sq_add_cos_sq x,
sq, sq, ← sub_eq_iff_eq_add, sub_self];
exact ⟨λ h, by rw [h, mul_zero], eq_zero_of_mul_self_eq_zero ∘ eq.symm⟩
lemma cos_eq_one_iff (x : ℝ) : cos x = 1 ↔ ∃ n : ℤ, (n : ℝ) * (2 * π) = x :=
⟨λ h, let ⟨n, hn⟩ := sin_eq_zero_iff.1 (sin_eq_zero_iff_cos_eq.2 (or.inl h)) in
⟨n / 2, (int.mod_two_eq_zero_or_one n).elim
(λ hn0, by rwa [← mul_assoc, ← @int.cast_two ℝ, ← int.cast_mul, int.div_mul_cancel
((int.dvd_iff_mod_eq_zero _ _).2 hn0)])
(λ hn1, by rw [← int.mod_add_div n 2, hn1, int.cast_add, int.cast_one, add_mul,
one_mul, add_comm, mul_comm (2 : ℤ), int.cast_mul, mul_assoc, int.cast_two] at hn;
rw [← hn, cos_int_mul_two_pi_add_pi] at h;
exact absurd h (by norm_num))⟩,
λ ⟨n, hn⟩, hn ▸ cos_int_mul_two_pi _⟩
lemma cos_eq_one_iff_of_lt_of_lt {x : ℝ} (hx₁ : -(2 * π) < x) (hx₂ : x < 2 * π) :
cos x = 1 ↔ x = 0 :=
⟨λ h,
begin
rcases (cos_eq_one_iff _).1 h with ⟨n, rfl⟩,
rw [mul_lt_iff_lt_one_left two_pi_pos] at hx₂,
rw [neg_lt, neg_mul_eq_neg_mul, mul_lt_iff_lt_one_left two_pi_pos] at hx₁,
norm_cast at hx₁ hx₂,
obtain rfl : n = 0 := le_antisymm (by linarith) (by linarith),
simp
end,
λ h, by simp [h]⟩
lemma cos_lt_cos_of_nonneg_of_le_pi_div_two {x y : ℝ} (hx₁ : 0 ≤ x) (hy₂ : y ≤ π / 2)
(hxy : x < y) :
cos y < cos x :=
begin
rw [← sub_lt_zero, cos_sub_cos],
have : 0 < sin ((y + x) / 2),
{ refine sin_pos_of_pos_of_lt_pi _ _; linarith },
have : 0 < sin ((y - x) / 2),
{ refine sin_pos_of_pos_of_lt_pi _ _; linarith },
nlinarith,
end
lemma cos_lt_cos_of_nonneg_of_le_pi {x y : ℝ} (hx₁ : 0 ≤ x) (hy₂ : y ≤ π) (hxy : x < y) :
cos y < cos x :=
match (le_total x (π / 2) : x ≤ π / 2 ∨ π / 2 ≤ x), le_total y (π / 2) with
| or.inl hx, or.inl hy := cos_lt_cos_of_nonneg_of_le_pi_div_two hx₁ hy hxy
| or.inl hx, or.inr hy := (lt_or_eq_of_le hx).elim
(λ hx, calc cos y ≤ 0 : cos_nonpos_of_pi_div_two_le_of_le hy (by linarith [pi_pos])
... < cos x : cos_pos_of_mem_Ioo ⟨by linarith, hx⟩)
(λ hx, calc cos y < 0 : cos_neg_of_pi_div_two_lt_of_lt (by linarith) (by linarith [pi_pos])
... = cos x : by rw [hx, cos_pi_div_two])
| or.inr hx, or.inl hy := by linarith
| or.inr hx, or.inr hy := neg_lt_neg_iff.1 (by rw [← cos_pi_sub, ← cos_pi_sub];
apply cos_lt_cos_of_nonneg_of_le_pi_div_two; linarith)
end
lemma strict_anti_on_cos : strict_anti_on cos (Icc 0 π) :=
λ x hx y hy hxy, cos_lt_cos_of_nonneg_of_le_pi hx.1 hy.2 hxy
lemma cos_le_cos_of_nonneg_of_le_pi {x y : ℝ} (hx₁ : 0 ≤ x) (hy₂ : y ≤ π) (hxy : x ≤ y) :
cos y ≤ cos x :=
(strict_anti_on_cos.le_iff_le ⟨hx₁.trans hxy, hy₂⟩ ⟨hx₁, hxy.trans hy₂⟩).2 hxy
lemma sin_lt_sin_of_lt_of_le_pi_div_two {x y : ℝ} (hx₁ : -(π / 2) ≤ x)
(hy₂ : y ≤ π / 2) (hxy : x < y) : sin x < sin y :=
by rw [← cos_sub_pi_div_two, ← cos_sub_pi_div_two, ← cos_neg (x - _), ← cos_neg (y - _)];
apply cos_lt_cos_of_nonneg_of_le_pi; linarith
lemma strict_mono_on_sin : strict_mono_on sin (Icc (-(π / 2)) (π / 2)) :=
λ x hx y hy hxy, sin_lt_sin_of_lt_of_le_pi_div_two hx.1 hy.2 hxy
lemma sin_le_sin_of_le_of_le_pi_div_two {x y : ℝ} (hx₁ : -(π / 2) ≤ x)
(hy₂ : y ≤ π / 2) (hxy : x ≤ y) : sin x ≤ sin y :=
(strict_mono_on_sin.le_iff_le ⟨hx₁, hxy.trans hy₂⟩ ⟨hx₁.trans hxy, hy₂⟩).2 hxy
lemma inj_on_sin : inj_on sin (Icc (-(π / 2)) (π / 2)) :=
strict_mono_on_sin.inj_on
lemma inj_on_cos : inj_on cos (Icc 0 π) := strict_anti_on_cos.inj_on
lemma surj_on_sin : surj_on sin (Icc (-(π / 2)) (π / 2)) (Icc (-1) 1) :=
by simpa only [sin_neg, sin_pi_div_two]
using intermediate_value_Icc (neg_le_self pi_div_two_pos.le) continuous_sin.continuous_on
lemma surj_on_cos : surj_on cos (Icc 0 π) (Icc (-1) 1) :=
by simpa only [cos_zero, cos_pi]
using intermediate_value_Icc' pi_pos.le continuous_cos.continuous_on
lemma sin_mem_Icc (x : ℝ) : sin x ∈ Icc (-1 : ℝ) 1 := ⟨neg_one_le_sin x, sin_le_one x⟩
lemma cos_mem_Icc (x : ℝ) : cos x ∈ Icc (-1 : ℝ) 1 := ⟨neg_one_le_cos x, cos_le_one x⟩
lemma maps_to_sin (s : set ℝ) : maps_to sin s (Icc (-1 : ℝ) 1) := λ x _, sin_mem_Icc x
lemma maps_to_cos (s : set ℝ) : maps_to cos s (Icc (-1 : ℝ) 1) := λ x _, cos_mem_Icc x
lemma bij_on_sin : bij_on sin (Icc (-(π / 2)) (π / 2)) (Icc (-1) 1) :=
⟨maps_to_sin _, inj_on_sin, surj_on_sin⟩
lemma bij_on_cos : bij_on cos (Icc 0 π) (Icc (-1) 1) :=
⟨maps_to_cos _, inj_on_cos, surj_on_cos⟩
@[simp] lemma range_cos : range cos = (Icc (-1) 1 : set ℝ) :=
subset.antisymm (range_subset_iff.2 cos_mem_Icc) surj_on_cos.subset_range
@[simp] lemma range_sin : range sin = (Icc (-1) 1 : set ℝ) :=
subset.antisymm (range_subset_iff.2 sin_mem_Icc) surj_on_sin.subset_range
lemma range_cos_infinite : (range real.cos).infinite :=
by { rw real.range_cos, exact Icc_infinite (by norm_num) }
lemma range_sin_infinite : (range real.sin).infinite :=
by { rw real.range_sin, exact Icc_infinite (by norm_num) }
section cos_div_sq
variable (x : ℝ)
/-- the series `sqrt_two_add_series x n` is `sqrt(2 + sqrt(2 + ... ))` with `n` square roots,
starting with `x`. We define it here because `cos (pi / 2 ^ (n+1)) = sqrt_two_add_series 0 n / 2`
-/
@[simp, pp_nodot] noncomputable def sqrt_two_add_series (x : ℝ) : ℕ → ℝ
| 0 := x
| (n+1) := sqrt (2 + sqrt_two_add_series n)
lemma sqrt_two_add_series_zero : sqrt_two_add_series x 0 = x := by simp
lemma sqrt_two_add_series_one : sqrt_two_add_series 0 1 = sqrt 2 := by simp
lemma sqrt_two_add_series_two : sqrt_two_add_series 0 2 = sqrt (2 + sqrt 2) := by simp
lemma sqrt_two_add_series_zero_nonneg : ∀(n : ℕ), 0 ≤ sqrt_two_add_series 0 n
| 0 := le_refl 0
| (n+1) := sqrt_nonneg _
lemma sqrt_two_add_series_nonneg {x : ℝ} (h : 0 ≤ x) : ∀(n : ℕ), 0 ≤ sqrt_two_add_series x n
| 0 := h
| (n+1) := sqrt_nonneg _
lemma sqrt_two_add_series_lt_two : ∀(n : ℕ), sqrt_two_add_series 0 n < 2
| 0 := by norm_num
| (n+1) :=
begin
refine lt_of_lt_of_le _ (sqrt_sq zero_lt_two.le).le,
rw [sqrt_two_add_series, sqrt_lt_sqrt_iff, ← lt_sub_iff_add_lt'],
{ refine (sqrt_two_add_series_lt_two n).trans_le _, norm_num },
{ exact add_nonneg zero_le_two (sqrt_two_add_series_zero_nonneg n) }
end
lemma sqrt_two_add_series_succ (x : ℝ) :
∀(n : ℕ), sqrt_two_add_series x (n+1) = sqrt_two_add_series (sqrt (2 + x)) n
| 0 := rfl
| (n+1) := by rw [sqrt_two_add_series, sqrt_two_add_series_succ, sqrt_two_add_series]
lemma sqrt_two_add_series_monotone_left {x y : ℝ} (h : x ≤ y) :
∀(n : ℕ), sqrt_two_add_series x n ≤ sqrt_two_add_series y n
| 0 := h
| (n+1) :=
begin
rw [sqrt_two_add_series, sqrt_two_add_series],
exact sqrt_le_sqrt (add_le_add_left (sqrt_two_add_series_monotone_left _) _)
end
@[simp] lemma cos_pi_over_two_pow : ∀(n : ℕ), cos (π / 2 ^ (n+1)) = sqrt_two_add_series 0 n / 2
| 0 := by simp
| (n+1) :=
begin
have : (2 : ℝ) ≠ 0 := two_ne_zero,
symmetry, rw [div_eq_iff_mul_eq this], symmetry,
rw [sqrt_two_add_series, sqrt_eq_iff_sq_eq, mul_pow, cos_sq, ←mul_div_assoc,
nat.add_succ, pow_succ, mul_div_mul_left _ _ this, cos_pi_over_two_pow, add_mul],
congr, { norm_num },
rw [mul_comm, sq, mul_assoc, ←mul_div_assoc, mul_div_cancel_left, ←mul_div_assoc,
mul_div_cancel_left]; try { exact this },
apply add_nonneg, norm_num, apply sqrt_two_add_series_zero_nonneg, norm_num,
apply le_of_lt, apply cos_pos_of_mem_Ioo ⟨_, _⟩,
{ transitivity (0 : ℝ), rw neg_lt_zero, apply pi_div_two_pos,
apply div_pos pi_pos, apply pow_pos, norm_num },
apply div_lt_div' (le_refl π) _ pi_pos _,
refine lt_of_le_of_lt (le_of_eq (pow_one _).symm) _,
apply pow_lt_pow, norm_num, apply nat.succ_lt_succ, apply nat.succ_pos, all_goals {norm_num}
end
lemma sin_sq_pi_over_two_pow (n : ℕ) :
sin (π / 2 ^ (n+1)) ^ 2 = 1 - (sqrt_two_add_series 0 n / 2) ^ 2 :=
by rw [sin_sq, cos_pi_over_two_pow]
lemma sin_sq_pi_over_two_pow_succ (n : ℕ) :
sin (π / 2 ^ (n+2)) ^ 2 = 1 / 2 - sqrt_two_add_series 0 n / 4 :=
begin
rw [sin_sq_pi_over_two_pow, sqrt_two_add_series, div_pow, sq_sqrt, add_div, ←sub_sub],
congr, norm_num, norm_num, apply add_nonneg, norm_num, apply sqrt_two_add_series_zero_nonneg,
end
@[simp] lemma sin_pi_over_two_pow_succ (n : ℕ) :
sin (π / 2 ^ (n+2)) = sqrt (2 - sqrt_two_add_series 0 n) / 2 :=
begin
symmetry, rw [div_eq_iff_mul_eq], symmetry,
rw [sqrt_eq_iff_sq_eq, mul_pow, sin_sq_pi_over_two_pow_succ, sub_mul],
{ congr, norm_num, rw [mul_comm], convert mul_div_cancel' _ _, norm_num, norm_num },
{ rw [sub_nonneg], apply le_of_lt, apply sqrt_two_add_series_lt_two },
apply le_of_lt, apply mul_pos, apply sin_pos_of_pos_of_lt_pi,
{ apply div_pos pi_pos, apply pow_pos, norm_num },
refine lt_of_lt_of_le _ (le_of_eq (div_one _)), rw [div_lt_div_left],
refine lt_of_le_of_lt (le_of_eq (pow_zero 2).symm) _,
apply pow_lt_pow, norm_num, apply nat.succ_pos, apply pi_pos,
apply pow_pos, all_goals {norm_num}
end
@[simp] lemma cos_pi_div_four : cos (π / 4) = sqrt 2 / 2 :=
by { transitivity cos (π / 2 ^ 2), congr, norm_num, simp }
@[simp] lemma sin_pi_div_four : sin (π / 4) = sqrt 2 / 2 :=
by { transitivity sin (π / 2 ^ 2), congr, norm_num, simp }
@[simp] lemma cos_pi_div_eight : cos (π / 8) = sqrt (2 + sqrt 2) / 2 :=
by { transitivity cos (π / 2 ^ 3), congr, norm_num, simp }
@[simp] lemma sin_pi_div_eight : sin (π / 8) = sqrt (2 - sqrt 2) / 2 :=
by { transitivity sin (π / 2 ^ 3), congr, norm_num, simp }
@[simp] lemma cos_pi_div_sixteen : cos (π / 16) = sqrt (2 + sqrt (2 + sqrt 2)) / 2 :=
by { transitivity cos (π / 2 ^ 4), congr, norm_num, simp }
@[simp] lemma sin_pi_div_sixteen : sin (π / 16) = sqrt (2 - sqrt (2 + sqrt 2)) / 2 :=
by { transitivity sin (π / 2 ^ 4), congr, norm_num, simp }
@[simp] lemma cos_pi_div_thirty_two : cos (π / 32) = sqrt (2 + sqrt (2 + sqrt (2 + sqrt 2))) / 2 :=
by { transitivity cos (π / 2 ^ 5), congr, norm_num, simp }
@[simp] lemma sin_pi_div_thirty_two : sin (π / 32) = sqrt (2 - sqrt (2 + sqrt (2 + sqrt 2))) / 2 :=
by { transitivity sin (π / 2 ^ 5), congr, norm_num, simp }
-- This section is also a convenient location for other explicit values of `sin` and `cos`.
/-- The cosine of `π / 3` is `1 / 2`. -/
@[simp] lemma cos_pi_div_three : cos (π / 3) = 1 / 2 :=
begin
have h₁ : (2 * cos (π / 3) - 1) ^ 2 * (2 * cos (π / 3) + 2) = 0,
{ have : cos (3 * (π / 3)) = cos π := by { congr' 1, ring },
linarith [cos_pi, cos_three_mul (π / 3)] },
cases mul_eq_zero.mp h₁ with h h,
{ linarith [pow_eq_zero h] },
{ have : cos π < cos (π / 3),
{ refine cos_lt_cos_of_nonneg_of_le_pi _ rfl.ge _;
linarith [pi_pos] },
linarith [cos_pi] }
end
/-- The square of the cosine of `π / 6` is `3 / 4` (this is sometimes more convenient than the
result for cosine itself). -/
lemma sq_cos_pi_div_six : cos (π / 6) ^ 2 = 3 / 4 :=
begin
have h1 : cos (π / 6) ^ 2 = 1 / 2 + 1 / 2 / 2,
{ convert cos_sq (π / 6),
have h2 : 2 * (π / 6) = π / 3 := by cancel_denoms,
rw [h2, cos_pi_div_three] },
rw ← sub_eq_zero at h1 ⊢,
convert h1 using 1,
ring
end
/-- The cosine of `π / 6` is `√3 / 2`. -/
@[simp] lemma cos_pi_div_six : cos (π / 6) = (sqrt 3) / 2 :=
begin
suffices : sqrt 3 = cos (π / 6) * 2,
{ field_simp [(by norm_num : 0 ≠ 2)], exact this.symm },
rw sqrt_eq_iff_sq_eq,
{ have h1 := (mul_right_inj' (by norm_num : (4:ℝ) ≠ 0)).mpr sq_cos_pi_div_six,
rw ← sub_eq_zero at h1 ⊢,
convert h1 using 1,
ring },
{ norm_num },
{ have : 0 < cos (π / 6) := by { apply cos_pos_of_mem_Ioo; split; linarith [pi_pos] },
linarith },
end
/-- The sine of `π / 6` is `1 / 2`. -/
@[simp] lemma sin_pi_div_six : sin (π / 6) = 1 / 2 :=
begin
rw [← cos_pi_div_two_sub, ← cos_pi_div_three],
congr,
ring
end
/-- The square of the sine of `π / 3` is `3 / 4` (this is sometimes more convenient than the
result for cosine itself). -/
lemma sq_sin_pi_div_three : sin (π / 3) ^ 2 = 3 / 4 :=
begin
rw [← cos_pi_div_two_sub, ← sq_cos_pi_div_six],
congr,
ring
end
/-- The sine of `π / 3` is `√3 / 2`. -/
@[simp] lemma sin_pi_div_three : sin (π / 3) = (sqrt 3) / 2 :=
begin
rw [← cos_pi_div_two_sub, ← cos_pi_div_six],
congr,
ring
end
end cos_div_sq
/-- `real.sin` as an `order_iso` between `[-(π / 2), π / 2]` and `[-1, 1]`. -/
def sin_order_iso : Icc (-(π / 2)) (π / 2) ≃o Icc (-1:ℝ) 1 :=
(strict_mono_on_sin.order_iso _ _).trans $ order_iso.set_congr _ _ bij_on_sin.image_eq
@[simp] lemma coe_sin_order_iso_apply (x : Icc (-(π / 2)) (π / 2)) :
(sin_order_iso x : ℝ) = sin x := rfl
lemma sin_order_iso_apply (x : Icc (-(π / 2)) (π / 2)) :
sin_order_iso x = ⟨sin x, sin_mem_Icc x⟩ := rfl
@[simp] lemma tan_pi_div_four : tan (π / 4) = 1 :=
begin
rw [tan_eq_sin_div_cos, cos_pi_div_four, sin_pi_div_four],
have h : (sqrt 2) / 2 > 0 := by cancel_denoms,
exact div_self (ne_of_gt h),
end
@[simp] lemma tan_pi_div_two : tan (π / 2) = 0 := by simp [tan_eq_sin_div_cos]
lemma tan_pos_of_pos_of_lt_pi_div_two {x : ℝ} (h0x : 0 < x) (hxp : x < π / 2) : 0 < tan x :=
by rw tan_eq_sin_div_cos; exact div_pos (sin_pos_of_pos_of_lt_pi h0x (by linarith))
(cos_pos_of_mem_Ioo ⟨by linarith, hxp⟩)
lemma tan_nonneg_of_nonneg_of_le_pi_div_two {x : ℝ} (h0x : 0 ≤ x) (hxp : x ≤ π / 2) : 0 ≤ tan x :=
match lt_or_eq_of_le h0x, lt_or_eq_of_le hxp with
| or.inl hx0, or.inl hxp := le_of_lt (tan_pos_of_pos_of_lt_pi_div_two hx0 hxp)
| or.inl hx0, or.inr hxp := by simp [hxp, tan_eq_sin_div_cos]
| or.inr hx0, _ := by simp [hx0.symm]
end
lemma tan_neg_of_neg_of_pi_div_two_lt {x : ℝ} (hx0 : x < 0) (hpx : -(π / 2) < x) : tan x < 0 :=
neg_pos.1 (tan_neg x ▸ tan_pos_of_pos_of_lt_pi_div_two (by linarith) (by linarith [pi_pos]))
lemma tan_nonpos_of_nonpos_of_neg_pi_div_two_le {x : ℝ} (hx0 : x ≤ 0) (hpx : -(π / 2) ≤ x) :
tan x ≤ 0 :=
neg_nonneg.1 (tan_neg x ▸ tan_nonneg_of_nonneg_of_le_pi_div_two (by linarith) (by linarith))
lemma tan_lt_tan_of_nonneg_of_lt_pi_div_two {x y : ℝ}
(hx₁ : 0 ≤ x) (hy₂ : y < π / 2) (hxy : x < y) :
tan x < tan y :=
begin
rw [tan_eq_sin_div_cos, tan_eq_sin_div_cos],
exact div_lt_div
(sin_lt_sin_of_lt_of_le_pi_div_two (by linarith) (le_of_lt hy₂) hxy)
(cos_le_cos_of_nonneg_of_le_pi hx₁ (by linarith) (le_of_lt hxy))
(sin_nonneg_of_nonneg_of_le_pi (by linarith) (by linarith))
(cos_pos_of_mem_Ioo ⟨by linarith, hy₂⟩)
end
lemma tan_lt_tan_of_lt_of_lt_pi_div_two {x y : ℝ} (hx₁ : -(π / 2) < x)
(hy₂ : y < π / 2) (hxy : x < y) : tan x < tan y :=
match le_total x 0, le_total y 0 with
| or.inl hx0, or.inl hy0 := neg_lt_neg_iff.1 $ by rw [← tan_neg, ← tan_neg]; exact
tan_lt_tan_of_nonneg_of_lt_pi_div_two (neg_nonneg.2 hy0)
(neg_lt.2 hx₁) (neg_lt_neg hxy)
| or.inl hx0, or.inr hy0 := (lt_or_eq_of_le hy0).elim
(λ hy0, calc tan x ≤ 0 : tan_nonpos_of_nonpos_of_neg_pi_div_two_le hx0 (le_of_lt hx₁)
... < tan y : tan_pos_of_pos_of_lt_pi_div_two hy0 hy₂)
(λ hy0, by rw [← hy0, tan_zero]; exact
tan_neg_of_neg_of_pi_div_two_lt (hy0.symm ▸ hxy) hx₁)
| or.inr hx0, or.inl hy0 := by linarith
| or.inr hx0, or.inr hy0 := tan_lt_tan_of_nonneg_of_lt_pi_div_two hx0 hy₂ hxy
end
lemma strict_mono_on_tan : strict_mono_on tan (Ioo (-(π / 2)) (π / 2)) :=
λ x hx y hy, tan_lt_tan_of_lt_of_lt_pi_div_two hx.1 hy.2
lemma inj_on_tan : inj_on tan (Ioo (-(π / 2)) (π / 2)) :=
strict_mono_on_tan.inj_on
lemma tan_inj_of_lt_of_lt_pi_div_two {x y : ℝ} (hx₁ : -(π / 2) < x) (hx₂ : x < π / 2)
(hy₁ : -(π / 2) < y) (hy₂ : y < π / 2) (hxy : tan x = tan y) : x = y :=
inj_on_tan ⟨hx₁, hx₂⟩ ⟨hy₁, hy₂⟩ hxy
lemma tan_periodic : function.periodic tan π :=
by simpa only [function.periodic, tan_eq_sin_div_cos] using sin_antiperiodic.div cos_antiperiodic
lemma tan_add_pi (x : ℝ) : tan (x + π) = tan x :=
tan_periodic x
lemma tan_sub_pi (x : ℝ) : tan (x - π) = tan x :=
tan_periodic.sub_eq x
lemma tan_pi_sub (x : ℝ) : tan (π - x) = -tan x :=
tan_neg x ▸ tan_periodic.sub_eq'
lemma tan_nat_mul_pi (n : ℕ) : tan (n * π) = 0 :=
tan_zero ▸ tan_periodic.nat_mul_eq n
lemma tan_int_mul_pi (n : ℤ) : tan (n * π) = 0 :=
tan_zero ▸ tan_periodic.int_mul_eq n
lemma tan_add_nat_mul_pi (x : ℝ) (n : ℕ) : tan (x + n * π) = tan x :=
tan_periodic.nat_mul n x
lemma tan_add_int_mul_pi (x : ℝ) (n : ℤ) : tan (x + n * π) = tan x :=
tan_periodic.int_mul n x
lemma tan_sub_nat_mul_pi (x : ℝ) (n : ℕ) : tan (x - n * π) = tan x :=
tan_periodic.sub_nat_mul_eq n
lemma tan_sub_int_mul_pi (x : ℝ) (n : ℤ) : tan (x - n * π) = tan x :=
tan_periodic.sub_int_mul_eq n
lemma tan_nat_mul_pi_sub (x : ℝ) (n : ℕ) : tan (n * π - x) = -tan x :=
tan_neg x ▸ tan_periodic.nat_mul_sub_eq n
lemma tan_int_mul_pi_sub (x : ℝ) (n : ℤ) : tan (n * π - x) = -tan x :=
tan_neg x ▸ tan_periodic.int_mul_sub_eq n
lemma tendsto_sin_pi_div_two : tendsto sin (𝓝[<] (π/2)) (𝓝 1) :=
by { convert continuous_sin.continuous_within_at, simp }
lemma tendsto_cos_pi_div_two : tendsto cos (𝓝[<] (π/2)) (𝓝[>] 0) :=
begin
apply tendsto_nhds_within_of_tendsto_nhds_of_eventually_within,
{ convert continuous_cos.continuous_within_at, simp },
{ filter_upwards [Ioo_mem_nhds_within_Iio (right_mem_Ioc.mpr (neg_lt_self pi_div_two_pos))]
with x hx using cos_pos_of_mem_Ioo hx },
end
lemma tendsto_tan_pi_div_two : tendsto tan (𝓝[<] (π/2)) at_top :=
begin
convert tendsto_cos_pi_div_two.inv_tendsto_zero.at_top_mul zero_lt_one
tendsto_sin_pi_div_two,
simp only [pi.inv_apply, ← div_eq_inv_mul, ← tan_eq_sin_div_cos]
end
lemma tendsto_sin_neg_pi_div_two : tendsto sin (𝓝[>] (-(π/2))) (𝓝 (-1)) :=
by { convert continuous_sin.continuous_within_at, simp }
lemma tendsto_cos_neg_pi_div_two : tendsto cos (𝓝[>] (-(π/2))) (𝓝[>] 0) :=
begin
apply tendsto_nhds_within_of_tendsto_nhds_of_eventually_within,
{ convert continuous_cos.continuous_within_at, simp },
{ filter_upwards [Ioo_mem_nhds_within_Ioi (left_mem_Ico.mpr (neg_lt_self pi_div_two_pos))]
with x hx using cos_pos_of_mem_Ioo hx },
end
lemma tendsto_tan_neg_pi_div_two : tendsto tan (𝓝[>] (-(π/2))) at_bot :=
begin
convert tendsto_cos_neg_pi_div_two.inv_tendsto_zero.at_top_mul_neg (by norm_num)
tendsto_sin_neg_pi_div_two,
simp only [pi.inv_apply, ← div_eq_inv_mul, ← tan_eq_sin_div_cos]
end
end real
namespace complex
open_locale real
lemma sin_eq_zero_iff_cos_eq {z : ℂ} : sin z = 0 ↔ cos z = 1 ∨ cos z = -1 :=
by rw [← mul_self_eq_one_iff, ← sin_sq_add_cos_sq, sq, sq, ← sub_eq_iff_eq_add, sub_self];
exact ⟨λ h, by rw [h, mul_zero], eq_zero_of_mul_self_eq_zero ∘ eq.symm⟩
@[simp] lemma cos_pi_div_two : cos (π / 2) = 0 :=
calc cos (π / 2) = real.cos (π / 2) : by rw [of_real_cos]; simp
... = 0 : by simp
@[simp] lemma sin_pi_div_two : sin (π / 2) = 1 :=
calc sin (π / 2) = real.sin (π / 2) : by rw [of_real_sin]; simp
... = 1 : by simp
@[simp] lemma sin_pi : sin π = 0 :=
by rw [← of_real_sin, real.sin_pi]; simp
@[simp] lemma cos_pi : cos π = -1 :=
by rw [← of_real_cos, real.cos_pi]; simp
@[simp] lemma sin_two_pi : sin (2 * π) = 0 :=
by simp [two_mul, sin_add]
@[simp] lemma cos_two_pi : cos (2 * π) = 1 :=
by simp [two_mul, cos_add]
lemma sin_antiperiodic : function.antiperiodic sin π :=
by simp [sin_add]
lemma sin_periodic : function.periodic sin (2 * π) :=
sin_antiperiodic.periodic
lemma sin_add_pi (x : ℂ) : sin (x + π) = -sin x :=
sin_antiperiodic x
lemma sin_add_two_pi (x : ℂ) : sin (x + 2 * π) = sin x :=
sin_periodic x
lemma sin_sub_pi (x : ℂ) : sin (x - π) = -sin x :=
sin_antiperiodic.sub_eq x
lemma sin_sub_two_pi (x : ℂ) : sin (x - 2 * π) = sin x :=
sin_periodic.sub_eq x
lemma sin_pi_sub (x : ℂ) : sin (π - x) = sin x :=
neg_neg (sin x) ▸ sin_neg x ▸ sin_antiperiodic.sub_eq'
lemma sin_two_pi_sub (x : ℂ) : sin (2 * π - x) = -sin x :=
sin_neg x ▸ sin_periodic.sub_eq'
lemma sin_nat_mul_pi (n : ℕ) : sin (n * π) = 0 :=
sin_antiperiodic.nat_mul_eq_of_eq_zero sin_zero n
lemma sin_int_mul_pi (n : ℤ) : sin (n * π) = 0 :=
sin_antiperiodic.int_mul_eq_of_eq_zero sin_zero n
lemma sin_add_nat_mul_two_pi (x : ℂ) (n : ℕ) : sin (x + n * (2 * π)) = sin x :=
sin_periodic.nat_mul n x
lemma sin_add_int_mul_two_pi (x : ℂ) (n : ℤ) : sin (x + n * (2 * π)) = sin x :=
sin_periodic.int_mul n x
lemma sin_sub_nat_mul_two_pi (x : ℂ) (n : ℕ) : sin (x - n * (2 * π)) = sin x :=
sin_periodic.sub_nat_mul_eq n
lemma sin_sub_int_mul_two_pi (x : ℂ) (n : ℤ) : sin (x - n * (2 * π)) = sin x :=
sin_periodic.sub_int_mul_eq n
lemma sin_nat_mul_two_pi_sub (x : ℂ) (n : ℕ) : sin (n * (2 * π) - x) = -sin x :=
sin_neg x ▸ sin_periodic.nat_mul_sub_eq n
lemma sin_int_mul_two_pi_sub (x : ℂ) (n : ℤ) : sin (n * (2 * π) - x) = -sin x :=
sin_neg x ▸ sin_periodic.int_mul_sub_eq n
lemma cos_antiperiodic : function.antiperiodic cos π :=
by simp [cos_add]
lemma cos_periodic : function.periodic cos (2 * π) :=
cos_antiperiodic.periodic
lemma cos_add_pi (x : ℂ) : cos (x + π) = -cos x :=
cos_antiperiodic x
lemma cos_add_two_pi (x : ℂ) : cos (x + 2 * π) = cos x :=
cos_periodic x
lemma cos_sub_pi (x : ℂ) : cos (x - π) = -cos x :=
cos_antiperiodic.sub_eq x
lemma cos_sub_two_pi (x : ℂ) : cos (x - 2 * π) = cos x :=
cos_periodic.sub_eq x
lemma cos_pi_sub (x : ℂ) : cos (π - x) = -cos x :=
cos_neg x ▸ cos_antiperiodic.sub_eq'
lemma cos_two_pi_sub (x : ℂ) : cos (2 * π - x) = cos x :=
cos_neg x ▸ cos_periodic.sub_eq'
lemma cos_nat_mul_two_pi (n : ℕ) : cos (n * (2 * π)) = 1 :=
(cos_periodic.nat_mul_eq n).trans cos_zero
lemma cos_int_mul_two_pi (n : ℤ) : cos (n * (2 * π)) = 1 :=
(cos_periodic.int_mul_eq n).trans cos_zero
lemma cos_add_nat_mul_two_pi (x : ℂ) (n : ℕ) : cos (x + n * (2 * π)) = cos x :=
cos_periodic.nat_mul n x
lemma cos_add_int_mul_two_pi (x : ℂ) (n : ℤ) : cos (x + n * (2 * π)) = cos x :=
cos_periodic.int_mul n x
lemma cos_sub_nat_mul_two_pi (x : ℂ) (n : ℕ) : cos (x - n * (2 * π)) = cos x :=
cos_periodic.sub_nat_mul_eq n
lemma cos_sub_int_mul_two_pi (x : ℂ) (n : ℤ) : cos (x - n * (2 * π)) = cos x :=
cos_periodic.sub_int_mul_eq n
lemma cos_nat_mul_two_pi_sub (x : ℂ) (n : ℕ) : cos (n * (2 * π) - x) = cos x :=
cos_neg x ▸ cos_periodic.nat_mul_sub_eq n
lemma cos_int_mul_two_pi_sub (x : ℂ) (n : ℤ) : cos (n * (2 * π) - x) = cos x :=
cos_neg x ▸ cos_periodic.int_mul_sub_eq n
lemma cos_nat_mul_two_pi_add_pi (n : ℕ) : cos (n * (2 * π) + π) = -1 :=
by simpa only [cos_zero] using (cos_periodic.nat_mul n).add_antiperiod_eq cos_antiperiodic
lemma cos_int_mul_two_pi_add_pi (n : ℤ) : cos (n * (2 * π) + π) = -1 :=
by simpa only [cos_zero] using (cos_periodic.int_mul n).add_antiperiod_eq cos_antiperiodic
lemma cos_nat_mul_two_pi_sub_pi (n : ℕ) : cos (n * (2 * π) - π) = -1 :=
by simpa only [cos_zero] using (cos_periodic.nat_mul n).sub_antiperiod_eq cos_antiperiodic
lemma cos_int_mul_two_pi_sub_pi (n : ℤ) : cos (n * (2 * π) - π) = -1 :=
by simpa only [cos_zero] using (cos_periodic.int_mul n).sub_antiperiod_eq cos_antiperiodic
lemma sin_add_pi_div_two (x : ℂ) : sin (x + π / 2) = cos x :=
by simp [sin_add]
lemma sin_sub_pi_div_two (x : ℂ) : sin (x - π / 2) = -cos x :=
by simp [sub_eq_add_neg, sin_add]
lemma sin_pi_div_two_sub (x : ℂ) : sin (π / 2 - x) = cos x :=
by simp [sub_eq_add_neg, sin_add]
lemma cos_add_pi_div_two (x : ℂ) : cos (x + π / 2) = -sin x :=
by simp [cos_add]
lemma cos_sub_pi_div_two (x : ℂ) : cos (x - π / 2) = sin x :=
by simp [sub_eq_add_neg, cos_add]
lemma cos_pi_div_two_sub (x : ℂ) : cos (π / 2 - x) = sin x :=
by rw [← cos_neg, neg_sub, cos_sub_pi_div_two]
lemma tan_periodic : function.periodic tan π :=
by simpa only [tan_eq_sin_div_cos] using sin_antiperiodic.div cos_antiperiodic
lemma tan_add_pi (x : ℂ) : tan (x + π) = tan x :=
tan_periodic x
lemma tan_sub_pi (x : ℂ) : tan (x - π) = tan x :=
tan_periodic.sub_eq x
lemma tan_pi_sub (x : ℂ) : tan (π - x) = -tan x :=
tan_neg x ▸ tan_periodic.sub_eq'
lemma tan_nat_mul_pi (n : ℕ) : tan (n * π) = 0 :=
tan_zero ▸ tan_periodic.nat_mul_eq n
lemma tan_int_mul_pi (n : ℤ) : tan (n * π) = 0 :=
tan_zero ▸ tan_periodic.int_mul_eq n
lemma tan_add_nat_mul_pi (x : ℂ) (n : ℕ) : tan (x + n * π) = tan x :=
tan_periodic.nat_mul n x
lemma tan_add_int_mul_pi (x : ℂ) (n : ℤ) : tan (x + n * π) = tan x :=
tan_periodic.int_mul n x
lemma tan_sub_nat_mul_pi (x : ℂ) (n : ℕ) : tan (x - n * π) = tan x :=
tan_periodic.sub_nat_mul_eq n
lemma tan_sub_int_mul_pi (x : ℂ) (n : ℤ) : tan (x - n * π) = tan x :=
tan_periodic.sub_int_mul_eq n
lemma tan_nat_mul_pi_sub (x : ℂ) (n : ℕ) : tan (n * π - x) = -tan x :=
tan_neg x ▸ tan_periodic.nat_mul_sub_eq n
lemma tan_int_mul_pi_sub (x : ℂ) (n : ℤ) : tan (n * π - x) = -tan x :=
tan_neg x ▸ tan_periodic.int_mul_sub_eq n
lemma exp_antiperiodic : function.antiperiodic exp (π * I) :=
by simp [exp_add, exp_mul_I]
lemma exp_periodic : function.periodic exp (2 * π * I) :=
(mul_assoc (2:ℂ) π I).symm ▸ exp_antiperiodic.periodic
lemma exp_mul_I_antiperiodic : function.antiperiodic (λ x, exp (x * I)) π :=
by simpa only [mul_inv_cancel_right₀ I_ne_zero] using exp_antiperiodic.mul_const I_ne_zero
lemma exp_mul_I_periodic : function.periodic (λ x, exp (x * I)) (2 * π) :=
exp_mul_I_antiperiodic.periodic
@[simp] lemma exp_pi_mul_I : exp (π * I) = -1 :=
exp_zero ▸ exp_antiperiodic.eq
@[simp] lemma exp_two_pi_mul_I : exp (2 * π * I) = 1 :=
exp_periodic.eq.trans exp_zero
@[simp] lemma exp_nat_mul_two_pi_mul_I (n : ℕ) : exp (n * (2 * π * I)) = 1 :=
(exp_periodic.nat_mul_eq n).trans exp_zero
@[simp] lemma exp_int_mul_two_pi_mul_I (n : ℤ) : exp (n * (2 * π * I)) = 1 :=
(exp_periodic.int_mul_eq n).trans exp_zero
@[simp] lemma exp_add_pi_mul_I (z : ℂ) : exp (z + π * I) = -exp z :=
exp_antiperiodic z
@[simp] lemma exp_sub_pi_mul_I (z : ℂ) : exp (z - π * I) = -exp z :=
exp_antiperiodic.sub_eq z
/-- A supporting lemma for the **Phragmen-Lindelöf principle** in a horizontal strip. If `z : ℂ`
belongs to a horizontal strip `|complex.im z| ≤ b`, `b ≤ π / 2`, and `a ≤ 0`, then
$$\left|exp^{a\left(e^{z}+e^{-z}\right)}\right| \le e^{a\cos b \exp^{|re z|}}.$$
-/
lemma abs_exp_mul_exp_add_exp_neg_le_of_abs_im_le {a b : ℝ} (ha : a ≤ 0)
{z : ℂ} (hz : |z.im| ≤ b) (hb : b ≤ π / 2) :
abs (exp (a * (exp z + exp (-z)))) ≤ real.exp (a * real.cos b * real.exp (|z.re|)) :=
begin
simp only [abs_exp, real.exp_le_exp, of_real_mul_re, add_re, exp_re, neg_im, real.cos_neg,
← add_mul, mul_assoc, mul_comm (real.cos b), neg_re, ← real.cos_abs z.im],
have : real.exp (|z.re|) ≤ real.exp z.re + real.exp (-z.re),
from apply_abs_le_add_of_nonneg (λ x, (real.exp_pos x).le) z.re,
refine mul_le_mul_of_nonpos_left (mul_le_mul this _ _ ((real.exp_pos _).le.trans this)) ha,
{ exact real.cos_le_cos_of_nonneg_of_le_pi (_root_.abs_nonneg _)
(hb.trans $ half_le_self $ real.pi_pos.le) hz },
{ refine real.cos_nonneg_of_mem_Icc ⟨_, hb⟩,
exact (neg_nonpos.2 $ real.pi_div_two_pos.le).trans ((_root_.abs_nonneg _).trans hz) }
end
end complex
|
236d6f52bcaef384903c56dc385b11c962fcb0a5 | 56f08640ead9fe2e27938d1d9eee365a2a2d2a57 | /library/init/data/option_t.lean | 02bd26fa8bbb6805f7d0f4e16560e50068cf99a2 | [
"Apache-2.0"
] | permissive | jean-lucas/lean | 06cb5dc6422ae8be50685a2f09be7fc237ac5be6 | 7c63b2f046ea67ba61b9050bc683520209dc18e3 | refs/heads/master | 1,629,407,462,945 | 1,511,782,697,000 | 1,511,782,995,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 2,256 | lean | /-
Copyright (c) 2017 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
prelude
import init.meta.interactive init.category.transformers
universes u v
def option_t (m : Type u → Type v) [monad m] (α : Type u) : Type v :=
m (option α)
@[inline] def option_t_bind {m : Type u → Type v} [monad m] {α β : Type u} (a : option_t m α) (b : α → option_t m β)
: option_t m β :=
show m (option β), from
do o ← a,
match o with
| none := return none
| (some a) := b a
end
@[inline] def option_t_return {m : Type u → Type v} [monad m] {α : Type u} (a : α) : option_t m α :=
show m (option α), from
return (some a)
instance {m : Type u → Type v} [monad m] : monad (option_t m) :=
{pure := @option_t_return m _, bind := @option_t_bind m _,
id_map := begin
intros,
simp [option_t_bind, function.comp],
have h : option_t_bind._match_1 option_t_return = @pure m _ (option α),
{ apply funext, intro s, cases s, refl, refl },
{ simp [h], apply @monad.bind_pure _ (option α) m },
end,
pure_bind := begin
intros,
simp [option_t_bind, option_t_return, monad.pure_bind]
end,
bind_assoc :=
begin
intros,
simp [option_t_bind, option_t_return, monad.bind_assoc],
apply congr_arg, apply funext, intro x,
cases x,
{ simp [option_t_bind, monad.pure_bind] },
{ refl }
end}
def option_t_orelse {m : Type u → Type v} [monad m] {α : Type u} (a : option_t m α) (b : option_t m α) : option_t m α :=
show m (option α), from
do o ← a,
match o with
| none := b
| (some v) := return (some v)
end
def option_t_fail {m : Type u → Type v} [monad m] {α : Type u} : option_t m α :=
show m (option α), from
return none
instance {m : Type u → Type v} [monad m] : alternative (option_t m) :=
{ failure := @option_t_fail m _,
orelse := @option_t_orelse m _,
..@option_t.monad m _ }
def option_t.lift {m : Type u → Type v} [monad m] {α : Type u} (a : m α) : option_t m α :=
(some <$> a : m (option α))
instance option_t.monad_transformer : monad.monad_transformer option_t :=
{ is_monad := @option_t.monad,
monad_lift := @option_t.lift }
|
e3f8095903d5cdc58df3e986fe377e7ee1843f3d | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/t7.lean | 278eb1a8b0e6e336557cc78aa7f6b474c929e2fa | [
"Apache-2.0"
] | permissive | leanprover-community/lean | 12b87f69d92e614daea8bcc9d4de9a9ace089d0e | cce7990ea86a78bdb383e38ed7f9b5ba93c60ce0 | refs/heads/master | 1,687,508,156,644 | 1,684,951,104,000 | 1,684,951,104,000 | 169,960,991 | 457 | 107 | Apache-2.0 | 1,686,744,372,000 | 1,549,790,268,000 | C++ | UTF-8 | Lean | false | false | 72 | lean | constant A : Type.{1}
constant f : A → A → A
#print raw f _ (f _ _)
|
8bfeda800b8f52768c8965f6e2eec145898b7ac0 | dd4e652c749fea9ac77e404005cb3470e5f75469 | /src/missing_mathlib/data/multiset.lean | 79a4de094c4f59f57d5884ce8b8c5186ed216de4 | [] | no_license | skbaek/cvx | e32822ad5943541539966a37dee162b0a5495f55 | c50c790c9116f9fac8dfe742903a62bdd7292c15 | refs/heads/master | 1,623,803,010,339 | 1,618,058,958,000 | 1,618,058,958,000 | 176,293,135 | 3 | 2 | null | null | null | null | UTF-8 | Lean | false | false | 978 | lean | import data.multiset
@[reducible] noncomputable def multiset.to_list {α : Type*} (s : multiset α) := classical.some (quotient.exists_rep s)
@[simp] lemma multiset.to_list_zero {α : Type*} : (multiset.to_list 0 : list α) = [] :=
(multiset.coe_eq_zero _).1 (classical.some_spec (quotient.exists_rep multiset.zero))
lemma multiset.coe_to_list {α : Type*} (s : multiset α) : (s.to_list : multiset α) = s :=
classical.some_spec (quotient.exists_rep _)
lemma multiset.mem_to_list {α : Type*} (a : α) (s : multiset α) : a ∈ s.to_list ↔ a ∈ s :=
by rw [←multiset.mem_coe, multiset.coe_to_list]
/-
@[simp] lemma multiset.to_list_cons {α : Type*} (a : α) (as : list α) :
(multiset.to_list (a :: as) : list α) = [] := sorry
-/
lemma multiset.prod_eq_zero {α : Type*} [comm_semiring α] {s : multiset α} (h : (0 : α) ∈ s) :
multiset.prod s = 0 :=
begin
rcases multiset.exists_cons_of_mem h with ⟨s', hs'⟩,
simp [hs', multiset.prod_cons]
end |
45894f6ea794f5b5441f3cad6fe288b7f7789127 | a9d0fb7b0e4f802bd3857b803e6c5c23d87fef91 | /tests/lean/run/elab5.lean | 5cfa9673f4d7cfb8be43faef06ba4c3ff7e36231 | [
"Apache-2.0"
] | permissive | soonhokong/lean-osx | 4a954262c780e404c1369d6c06516161d07fcb40 | 3670278342d2f4faa49d95b46d86642d7875b47c | refs/heads/master | 1,611,410,334,552 | 1,474,425,686,000 | 1,474,425,686,000 | 12,043,103 | 5 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 557 | lean | set_option pp.implicit true
check (λ a b : nat, (nat.rec_on a (λ b, b) (λ a' ih b, ih b + 1) b : nat))
check (λ a b : nat, (nat.rec_on a (λ b, b) (λ a' ih b, ih b + 1) b : nat))
constants a b c : nat
constant p : nat → nat → Prop
constant f : nat → nat
axiom H1 : p (f a) (f a)
axiom H2 : a = b
axiom H3 : a = c
check (eq.subst H2 H1 : p (f a) (f b))
check (eq.subst H2 (eq.subst H3 H1) : p (f c) (f b))
axiom H4 : a + 1 = b
axiom H5 : p (a + nat.succ nat.zero) a
check (eq.subst H4 H5 : p b a)
|
9cd2f51e362c28836cc38a0ad7fc92ed6f9f512b | b2fe74b11b57d362c13326bc5651244f111fa6f4 | /src/category_theory/limits/preserves/limits.lean | 04065ef42c8147c0d2874dd7a801729c4dfbae6b | [
"Apache-2.0"
] | permissive | midfield/mathlib | c4db5fa898b5ac8f2f80ae0d00c95eb6f745f4c7 | 775edc615ecec631d65b6180dbcc7bc26c3abc26 | refs/heads/master | 1,675,330,551,921 | 1,608,304,514,000 | 1,608,304,514,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 3,723 | lean | /-
Copyright (c) 2020 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison, Bhavik Mehta
-/
import category_theory.limits.preserves.basic
import category_theory.limits.shapes
/-!
# Isomorphisms about functors which preserve (co)limits
If `G` preserves limits, and `C` and `D` have limits, then for any diagram `F : J ⥤ C` we have a
canonical isomorphism `preserves_limit_iso : G.obj (limit F) ≅ limit (F ⋙ G)`.
We also show that we can commute `is_limit.lift` of a preserved limit with `functor.map_cone`:
`(preserves_limit.preserves t).lift (G.map_cone c₂) = G.map (t.lift c₂)`.
The duals of these are also given. For functors which preserve (co)limits of specific shapes, see
`preserves/shapes.lean`.
-/
universes v u₁ u₂
noncomputable theory
namespace category_theory
open category limits
variables {C : Type u₁} [category.{v} C]
variables {D : Type u₂} [category.{v} D]
variables (G : C ⥤ D)
variables {J : Type v} [small_category J]
variables (F : J ⥤ C)
section
variables [preserves_limit F G]
@[simp]
lemma preserves_lift_map_cone (c₁ c₂ : cone F) (t : is_limit c₁) :
(preserves_limit.preserves t).lift (G.map_cone c₂) = G.map (t.lift c₂) :=
((preserves_limit.preserves t).uniq (G.map_cone c₂) _ (by simp [← G.map_comp])).symm
variables [has_limit F] [has_limit (F ⋙ G)]
/--
If `G` preserves limits, we have an isomorphism from the image of the limit of a functor `F`
to the limit of the functor `F ⋙ G`.
-/
def preserves_limit_iso : G.obj (limit F) ≅ limit (F ⋙ G) :=
(preserves_limit.preserves (limit.is_limit _)).cone_point_unique_up_to_iso (limit.is_limit _)
@[simp, reassoc]
lemma preserves_limits_iso_hom_π (j) :
(preserves_limit_iso G F).hom ≫ limit.π _ j = G.map (limit.π F j) :=
is_limit.cone_point_unique_up_to_iso_hom_comp _ _ j
@[simp, reassoc]
lemma preserves_limits_iso_inv_π (j) :
(preserves_limit_iso G F).inv ≫ G.map (limit.π F j) = limit.π _ j :=
is_limit.cone_point_unique_up_to_iso_inv_comp _ _ j
@[simp, reassoc]
lemma lift_comp_preserves_limits_iso_hom (t : cone F) :
G.map (limit.lift _ t) ≫ (preserves_limit_iso G F).hom = limit.lift (F ⋙ G) (G.map_cone _) :=
by { ext, simp [← G.map_comp] }
end
section
variables [preserves_colimit F G]
@[simp]
lemma preserves_desc_map_cocone (c₁ c₂ : cocone F) (t : is_colimit c₁) :
(preserves_colimit.preserves t).desc (G.map_cocone _) = G.map (t.desc c₂) :=
((preserves_colimit.preserves t).uniq (G.map_cocone _) _ (by simp [← G.map_comp])).symm
variables [has_colimit F] [has_colimit (F ⋙ G)]
/--
If `G` preserves colimits, we have an isomorphism from the image of the colimit of a functor `F`
to the colimit of the functor `F ⋙ G`.
-/
-- TODO: think about swapping the order here
def preserves_colimit_iso : G.obj (colimit F) ≅ colimit (F ⋙ G) :=
(preserves_colimit.preserves (colimit.is_colimit _)).cocone_point_unique_up_to_iso
(colimit.is_colimit _)
@[simp, reassoc]
lemma ι_preserves_colimits_iso_inv (j : J) :
colimit.ι _ j ≫ (preserves_colimit_iso G F).inv = G.map (colimit.ι F j) :=
is_colimit.comp_cocone_point_unique_up_to_iso_inv _ (colimit.is_colimit (F ⋙ G)) j
@[simp, reassoc]
lemma ι_preserves_colimits_iso_hom (j : J) :
G.map (colimit.ι F j) ≫ (preserves_colimit_iso G F).hom = colimit.ι (F ⋙ G) j :=
(preserves_colimit.preserves (colimit.is_colimit _)).comp_cocone_point_unique_up_to_iso_hom _ j
@[simp, reassoc]
lemma preserves_colimits_iso_inv_comp_desc (t : cocone F) :
(preserves_colimit_iso G F).inv ≫ G.map (colimit.desc _ t) = colimit.desc _ (G.map_cocone t) :=
by { ext, simp [← G.map_comp] }
end
end category_theory
|
c7d26eece037b927dea71b0b0ffc161b76d15539 | a7eef317ddec01b9fc6cfbb876fe7ac00f205ac7 | /src/data/set/function.lean | 36ea1024b6856aecb93776be0da001d76f93affc | [
"Apache-2.0"
] | permissive | kmill/mathlib | ea5a007b67ae4e9e18dd50d31d8aa60f650425ee | 1a419a9fea7b959317eddd556e1bb9639f4dcc05 | refs/heads/master | 1,668,578,197,719 | 1,593,629,163,000 | 1,593,629,163,000 | 276,482,939 | 0 | 0 | null | 1,593,637,960,000 | 1,593,637,959,000 | null | UTF-8 | Lean | false | false | 20,359 | lean | /-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Jeremy Avigad, Andrew Zipperer, Haitao Zhang, Minchao Wu, Yury Kudryashov
-/
import data.set.basic
import logic.function.conjugate
/-!
# Functions over sets
## Main definitions
### Predicate
* `eq_on f₁ f₂ s` : functions `f₁` and `f₂` are equal at every point of `s`;
* `maps_to f s t` : `f` sends every point of `s` to a point of `t`;
* `inj_on f s` : restriction of `f` to `s` is injective;
* `surj_on f s t` : every point in `s` has a preimage in `s`;
* `bij_on f s t` : `f` is a bijection between `s` and `t`;
* `left_inv_on f' f s` : for every `x ∈ s` we have `f' (f x) = x`;
* `right_inv_on f' f t` : for every `y ∈ t` we have `f (f' y) = y`;
* `inv_on f' f s t` : `f'` is a two-side inverse of `f` on `s` and `t`, i.e.
we have `left_inv_on f' f s` and `right_inv_on f' f t`.
### Functions
* `restrict f s` : restrict the domain of `f` to the set `s`;
* `cod_restrict f s h` : given `h : ∀ x, f x ∈ s`, restrict the codomain of `f` to the set `s`;
* `maps_to.restrict f s t h`: given `h : maps_to f s t`, restrict the domain of `f` to `s`
and the codomain to `t`.
-/
universes u v w x y
variables {α : Type u} {β : Type v} {γ : Type w} {ι : Sort x}
open function
namespace set
/-! ### Restrict -/
/-- Restrict domain of a function `f` to a set `s`. Same as `subtype.restrict` but this version
takes an argument `↥s` instead of `subtype s`. -/
def restrict (f : α → β) (s : set α) : s → β := λ x, f x
lemma restrict_eq (f : α → β) (s : set α) : s.restrict f = f ∘ coe := rfl
@[simp] lemma restrict_apply (f : α → β) (s : set α) (x : s) : restrict f s x = f x := rfl
@[simp] lemma range_restrict (f : α → β) (s : set α) : set.range (restrict f s) = f '' s :=
range_comp.trans $ congr_arg (('') f) subtype.range_coe
/-- Restrict codomain of a function `f` to a set `s`. Same as `subtype.coind` but this version
has codomain `↥s` instead of `subtype s`. -/
def cod_restrict (f : α → β) (s : set β) (h : ∀ x, f x ∈ s) : α → s :=
λ x, ⟨f x, h x⟩
@[simp] lemma coe_cod_restrict_apply (f : α → β) (s : set β) (h : ∀ x, f x ∈ s) (x : α) :
(cod_restrict f s h x : β) = f x :=
rfl
variables {s s₁ s₂ : set α} {t t₁ t₂ : set β} {p : set γ} {f f₁ f₂ f₃ : α → β} {g : β → γ}
{f' f₁' f₂' : β → α} {g' : γ → β}
/-! ### Equality on a set -/
/-- Two functions `f₁ f₂ : α → β` are equal on `s`
if `f₁ x = f₂ x` for all `x ∈ a`. -/
@[reducible] def eq_on (f₁ f₂ : α → β) (s : set α) : Prop :=
∀ ⦃x⦄, x ∈ s → f₁ x = f₂ x
@[symm] lemma eq_on.symm (h : eq_on f₁ f₂ s) : eq_on f₂ f₁ s :=
λ x hx, (h hx).symm
lemma eq_on_comm : eq_on f₁ f₂ s ↔ eq_on f₂ f₁ s :=
⟨eq_on.symm, eq_on.symm⟩
@[refl] lemma eq_on_refl (f : α → β) (s : set α) : eq_on f f s :=
λ _ _, rfl
@[trans] lemma eq_on.trans (h₁ : eq_on f₁ f₂ s) (h₂ : eq_on f₂ f₃ s) : eq_on f₁ f₃ s :=
λ x hx, (h₁ hx).trans (h₂ hx)
theorem eq_on.image_eq (heq : eq_on f₁ f₂ s) : f₁ '' s = f₂ '' s :=
image_congr heq
lemma eq_on.mono (hs : s₁ ⊆ s₂) (hf : eq_on f₁ f₂ s₂) : eq_on f₁ f₂ s₁ :=
λ x hx, hf (hs hx)
/-! ### maps to -/
/-- `maps_to f a b` means that the image of `a` is contained in `b`. -/
@[reducible] def maps_to (f : α → β) (s : set α) (t : set β) : Prop := ∀ ⦃x⦄, x ∈ s → f x ∈ t
/-- Given a map `f` sending `s : set α` into `t : set β`, restrict domain of `f` to `s`
and the codomain to `t`. Same as `subtype.map`. -/
def maps_to.restrict (f : α → β) (s : set α) (t : set β) (h : maps_to f s t) :
s → t :=
subtype.map f h
@[simp] lemma maps_to.coe_restrict_apply (h : maps_to f s t) (x : s) :
(h.restrict f s t x : β) = f x := rfl
theorem maps_to' : maps_to f s t ↔ f '' s ⊆ t :=
image_subset_iff.symm
theorem maps_to_empty (f : α → β) (t : set β) : maps_to f ∅ t := empty_subset _
theorem maps_to.image_subset (h : maps_to f s t) : f '' s ⊆ t :=
maps_to'.1 h
theorem maps_to.congr (h₁ : maps_to f₁ s t) (h : eq_on f₁ f₂ s) :
maps_to f₂ s t :=
λ x hx, h hx ▸ h₁ hx
theorem eq_on.maps_to_iff (H : eq_on f₁ f₂ s) : maps_to f₁ s t ↔ maps_to f₂ s t :=
⟨λ h, h.congr H, λ h, h.congr H.symm⟩
theorem maps_to.comp (h₁ : maps_to g t p) (h₂ : maps_to f s t) : maps_to (g ∘ f) s p :=
λ x h, h₁ (h₂ h)
theorem maps_to.iterate {f : α → α} {s : set α} (h : maps_to f s s) :
∀ n, maps_to (f^[n]) s s
| 0 := λ _, id
| (n+1) := (maps_to.iterate n).comp h
theorem maps_to.iterate_restrict {f : α → α} {s : set α} (h : maps_to f s s) (n : ℕ) :
(h.restrict f s s^[n]) = (h.iterate n).restrict _ _ _ :=
begin
funext x,
rw [subtype.ext_iff, maps_to.coe_restrict_apply],
induction n with n ihn generalizing x,
{ refl },
{ simp [nat.iterate, ihn] }
end
theorem maps_to.mono (hs : s₂ ⊆ s₁) (ht : t₁ ⊆ t₂) (hf : maps_to f s₁ t₁) :
maps_to f s₂ t₂ :=
λ x hx, ht (hf $ hs hx)
theorem maps_to_univ (f : α → β) (s : set α) : maps_to f s univ := λ x h, trivial
theorem maps_to_image (f : α → β) (s : set α) : maps_to f s (f '' s) := by rw maps_to'
theorem maps_to_preimage (f : α → β) (t : set β) : maps_to f (f ⁻¹' t) t := subset.refl _
theorem maps_to_range (f : set α) (s : set α) : maps_to f s (range f) :=
(maps_to_image f s).mono (subset.refl s) (image_subset_range _ _)
/-! ### Injectivity on a set -/
/-- `f` is injective on `a` if the restriction of `f` to `a` is injective. -/
@[reducible] def inj_on (f : α → β) (s : set α) : Prop :=
∀⦃x₁ x₂ : α⦄, x₁ ∈ s → x₂ ∈ s → f x₁ = f x₂ → x₁ = x₂
theorem inj_on_empty (f : α → β) : inj_on f ∅ :=
λ _ _ h₁ _ _, false.elim h₁
theorem inj_on.congr (h₁ : inj_on f₁ s) (h : eq_on f₁ f₂ s) :
inj_on f₂ s :=
λ x y hx hy, h hx ▸ h hy ▸ h₁ hx hy
theorem eq_on.inj_on_iff (H : eq_on f₁ f₂ s) : inj_on f₁ s ↔ inj_on f₂ s :=
⟨λ h, h.congr H, λ h, h.congr H.symm⟩
theorem inj_on.mono (h : s₁ ⊆ s₂) (ht : inj_on f s₂) : inj_on f s₁ :=
λ x y hx hy H, ht (h hx) (h hy) H
lemma injective_iff_inj_on_univ : injective f ↔ inj_on f univ :=
⟨λ h x y hx hy hxy, h hxy, λ h _ _ heq, h trivial trivial heq⟩
theorem inj_on.comp (hg : inj_on g t) (hf: inj_on f s) (h : maps_to f s t) :
inj_on (g ∘ f) s :=
λ x y hx hy heq, hf hx hy $ hg (h hx) (h hy) heq
lemma inj_on_iff_injective : inj_on f s ↔ injective (restrict f s) :=
⟨λ H a b h, subtype.eq $ H a.2 b.2 h,
λ H a b as bs h, congr_arg subtype.val $ @H ⟨a, as⟩ ⟨b, bs⟩ h⟩
lemma inj_on.inv_fun_on_image [nonempty α] (h : inj_on f s₂) (ht : s₁ ⊆ s₂) :
(inv_fun_on f s₂) '' (f '' s₁) = s₁ :=
begin
have : eq_on ((inv_fun_on f s₂) ∘ f) id s₁, from λz hz, inv_fun_on_eq' h (ht hz),
rw [← image_comp, this.image_eq, image_id]
end
lemma inj_on_preimage {B : set (set β)} (hB : B ⊆ powerset (range f)) :
inj_on (preimage f) B :=
begin
intros s t hs ht hst,
rw [←image_preimage_eq_of_subset (hB hs), ←image_preimage_eq_of_subset (hB ht), hst]
end
/-! ### Surjectivity on a set -/
/-- `f` is surjective from `a` to `b` if `b` is contained in the image of `a`. -/
@[reducible] def surj_on (f : α → β) (s : set α) (t : set β) : Prop := t ⊆ f '' s
theorem surj_on_empty (f : α → β) (s : set α) : surj_on f s ∅ := empty_subset _
theorem surj_on.comap_nonempty (h : surj_on f s t) (ht : t.nonempty) : s.nonempty :=
(ht.mono h).of_image
theorem surj_on.congr (h : surj_on f₁ s t) (H : eq_on f₁ f₂ s) : surj_on f₂ s t :=
by rwa [surj_on, ← H.image_eq]
theorem eq_on.surj_on_iff (h : eq_on f₁ f₂ s) : surj_on f₁ s t ↔ surj_on f₂ s t :=
⟨λ H, H.congr h, λ H, H.congr h.symm⟩
theorem surj_on.mono (hs : s₁ ⊆ s₂) (ht : t₁ ⊆ t₂) (hf : surj_on f s₁ t₂) : surj_on f s₂ t₁ :=
subset.trans ht $ subset.trans hf $ image_subset _ hs
theorem surj_on.comp (hg : surj_on g t p) (hf : surj_on f s t) : surj_on (g ∘ f) s p :=
subset.trans hg $ subset.trans (image_subset g hf) $ (image_comp g f s) ▸ subset.refl _
lemma surjective_iff_surj_on_univ : surjective f ↔ surj_on f univ univ :=
by simp [surjective, surj_on, subset_def]
lemma surj_on_iff_surjective : surj_on f s univ ↔ surjective (restrict f s) :=
⟨λ H b, let ⟨a, as, e⟩ := @H b trivial in ⟨⟨a, as⟩, e⟩,
λ H b _, let ⟨⟨a, as⟩, e⟩ := H b in ⟨a, as, e⟩⟩
lemma surj_on.image_eq_of_maps_to (h₁ : surj_on f s t) (h₂ : maps_to f s t) :
f '' s = t :=
eq_of_subset_of_subset h₂.image_subset h₁
/-! ### Bijectivity -/
/-- `f` is bijective from `s` to `t` if `f` is injective on `s` and `f '' s = t`. -/
@[reducible] def bij_on (f : α → β) (s : set α) (t : set β) : Prop :=
maps_to f s t ∧ inj_on f s ∧ surj_on f s t
lemma bij_on.maps_to (h : bij_on f s t) : maps_to f s t := h.left
lemma bij_on.inj_on (h : bij_on f s t) : inj_on f s := h.right.left
lemma bij_on.surj_on (h : bij_on f s t) : surj_on f s t := h.right.right
lemma bij_on.mk (h₁ : maps_to f s t) (h₂ : inj_on f s) (h₃ : surj_on f s t) :
bij_on f s t :=
⟨h₁, h₂, h₃⟩
lemma bij_on_empty (f : α → β) : bij_on f ∅ ∅ :=
⟨maps_to_empty f ∅, inj_on_empty f, surj_on_empty f ∅⟩
lemma inj_on.bij_on_image (h : inj_on f s) : bij_on f s (f '' s) :=
bij_on.mk (maps_to_image f s) h (subset.refl _)
theorem bij_on.congr (h₁ : bij_on f₁ s t) (h : eq_on f₁ f₂ s) :
bij_on f₂ s t :=
bij_on.mk (h₁.maps_to.congr h) (h₁.inj_on.congr h) (h₁.surj_on.congr h)
theorem eq_on.bij_on_iff (H : eq_on f₁ f₂ s) : bij_on f₁ s t ↔ bij_on f₂ s t :=
⟨λ h, h.congr H, λ h, h.congr H.symm⟩
lemma bij_on.image_eq (h : bij_on f s t) :
f '' s = t :=
h.surj_on.image_eq_of_maps_to h.maps_to
theorem bij_on.comp (hg : bij_on g t p) (hf : bij_on f s t) : bij_on (g ∘ f) s p :=
bij_on.mk (hg.maps_to.comp hf.maps_to) (hg.inj_on.comp hf.inj_on hf.maps_to)
(hg.surj_on.comp hf.surj_on)
lemma bijective_iff_bij_on_univ : bijective f ↔ bij_on f univ univ :=
iff.intro
(λ h, let ⟨inj, surj⟩ := h in
⟨maps_to_univ f _, iff.mp injective_iff_inj_on_univ inj, iff.mp surjective_iff_surj_on_univ surj⟩)
(λ h, let ⟨map, inj, surj⟩ := h in
⟨iff.mpr injective_iff_inj_on_univ inj, iff.mpr surjective_iff_surj_on_univ surj⟩)
/-! ### left inverse -/
/-- `g` is a left inverse to `f` on `a` means that `g (f x) = x` for all `x ∈ a`. -/
@[reducible] def left_inv_on (f' : β → α) (f : α → β) (s : set α) : Prop :=
∀ ⦃x⦄, x ∈ s → f' (f x) = x
lemma left_inv_on.eq_on (h : left_inv_on f' f s) : eq_on (f' ∘ f) id s := h
lemma left_inv_on.eq (h : left_inv_on f' f s) {x} (hx : x ∈ s) : f' (f x) = x := h hx
lemma left_inv_on.congr_left (h₁ : left_inv_on f₁' f s)
{t : set β} (h₁' : maps_to f s t) (heq : eq_on f₁' f₂' t) : left_inv_on f₂' f s :=
λ x hx, heq (h₁' hx) ▸ h₁ hx
theorem left_inv_on.congr_right (h₁ : left_inv_on f₁' f₁ s) (heq : eq_on f₁ f₂ s) :
left_inv_on f₁' f₂ s :=
λ x hx, heq hx ▸ h₁ hx
theorem left_inv_on.inj_on (h : left_inv_on f₁' f s) : inj_on f s :=
λ x₁ x₂ h₁ h₂ heq,
calc
x₁ = f₁' (f x₁) : eq.symm $ h h₁
... = f₁' (f x₂) : congr_arg f₁' heq
... = x₂ : h h₂
theorem left_inv_on.surj_on (h : left_inv_on f₁' f s) (hf : maps_to f s t) : surj_on f₁' t s :=
λ x hx, ⟨f x, hf hx, h hx⟩
theorem left_inv_on.comp (hf' : left_inv_on f' f s) (hg' : left_inv_on g' g t) (hf : maps_to f s t) :
left_inv_on (f' ∘ g') (g ∘ f) s :=
λ x h,
calc
(f' ∘ g') ((g ∘ f) x) = f' (f x) : congr_arg f' (hg' (hf h))
... = x : hf' h
/-! ### Right inverse -/
/-- `g` is a right inverse to `f` on `b` if `f (g x) = x` for all `x ∈ b`. -/
@[reducible] def right_inv_on (f' : β → α) (f : α → β) (t : set β) : Prop :=
left_inv_on f f' t
lemma right_inv_on.eq_on (h : right_inv_on f' f t) : eq_on (f ∘ f') id t := h
lemma right_inv_on.eq (h : right_inv_on f' f t) {y} (hy : y ∈ t) : f (f' y) = y := h hy
theorem right_inv_on.congr_left (h₁ : right_inv_on f₁' f t) (heq : eq_on f₁' f₂' t) :
right_inv_on f₂' f t :=
h₁.congr_right heq
theorem right_inv_on.congr_right (h₁ : right_inv_on f' f₁ t) (hg : maps_to f' t s)
(heq : eq_on f₁ f₂ s) : right_inv_on f' f₂ t :=
left_inv_on.congr_left h₁ hg heq
theorem right_inv_on.surj_on (hf : right_inv_on f' f t) (hf' : maps_to f' t s) :
surj_on f s t :=
hf.surj_on hf'
theorem right_inv_on.comp (hf : right_inv_on f' f t) (hg : right_inv_on g' g p)
(g'pt : maps_to g' p t) : right_inv_on (f' ∘ g') (g ∘ f) p :=
hg.comp hf g'pt
theorem inj_on.right_inv_on_of_left_inv_on (hf : inj_on f s) (hf' : left_inv_on f f' t)
(h₁ : maps_to f s t) (h₂ : maps_to f' t s) :
right_inv_on f f' s :=
λ x h, hf (h₂ $ h₁ h) h (hf' (h₁ h))
theorem eq_on_of_left_inv_on_of_right_inv_on (h₁ : left_inv_on f₁' f s) (h₂ : right_inv_on f₂' f t)
(h : maps_to f₂' t s) : eq_on f₁' f₂' t :=
λ y hy,
calc f₁' y = (f₁' ∘ f ∘ f₂') y : congr_arg f₁' (h₂ hy).symm
... = f₂' y : h₁ (h hy)
theorem surj_on.left_inv_on_of_right_inv_on (hf : surj_on f s t) (hf' : right_inv_on f f' s) :
left_inv_on f f' t :=
λ y hy, let ⟨x, hx, heq⟩ := hf hy in by rw [← heq, hf' hx]
/-! ### Two-side inverses -/
/-- `g` is an inverse to `f` viewed as a map from `a` to `b` -/
@[reducible] def inv_on (g : β → α) (f : α → β) (s : set α) (t : set β) : Prop :=
left_inv_on g f s ∧ right_inv_on g f t
lemma inv_on.symm (h : inv_on f' f s t) : inv_on f f' t s := ⟨h.right, h.left⟩
theorem inv_on.bij_on (h : inv_on f' f s t) (hf : maps_to f s t) (hf' : maps_to f' t s) :
bij_on f s t :=
⟨hf, h.left.inj_on, h.right.surj_on hf'⟩
/-! ### `inv_fun_on` is a left/right inverse -/
theorem inj_on.left_inv_on_inv_fun_on [nonempty α] (h : inj_on f s) :
left_inv_on (inv_fun_on f s) f s :=
λ x hx, inv_fun_on_eq' h hx
theorem surj_on.right_inv_on_inv_fun_on [nonempty α] (h : surj_on f s t) :
right_inv_on (inv_fun_on f s) f t :=
λ y hy, inv_fun_on_eq $ mem_image_iff_bex.1 $ h hy
theorem bij_on.inv_on_inv_fun_on [nonempty α] (h : bij_on f s t) :
inv_on (inv_fun_on f s) f s t :=
⟨h.inj_on.left_inv_on_inv_fun_on, h.surj_on.right_inv_on_inv_fun_on⟩
theorem surj_on.inv_on_inv_fun_on [nonempty α] (h : surj_on f s t) :
inv_on (inv_fun_on f s) f (inv_fun_on f s '' t) t :=
begin
refine ⟨_, h.right_inv_on_inv_fun_on⟩,
rintros _ ⟨y, hy, rfl⟩,
rw [h.right_inv_on_inv_fun_on hy]
end
theorem surj_on.maps_to_inv_fun_on [nonempty α] (h : surj_on f s t) :
maps_to (inv_fun_on f s) t s :=
λ y hy, mem_preimage.2 $ inv_fun_on_mem $ mem_image_iff_bex.1 $ h hy
theorem surj_on.bij_on_subset [nonempty α] (h : surj_on f s t) :
bij_on f (inv_fun_on f s '' t) t :=
begin
refine h.inv_on_inv_fun_on.bij_on _ (maps_to_image _ _),
rintros _ ⟨y, hy, rfl⟩,
rwa [h.right_inv_on_inv_fun_on hy]
end
theorem surj_on_iff_exists_bij_on_subset :
surj_on f s t ↔ ∃ s' ⊆ s, bij_on f s' t :=
begin
split,
{ rcases eq_empty_or_nonempty t with rfl|ht,
{ exact λ _, ⟨∅, empty_subset _, bij_on_empty f⟩ },
{ assume h,
haveI : nonempty α := ⟨classical.some (h.comap_nonempty ht)⟩,
exact ⟨_, h.maps_to_inv_fun_on.image_subset, h.bij_on_subset⟩ }},
{ rintros ⟨s', hs', hfs'⟩,
exact hfs'.surj_on.mono hs' (subset.refl _) }
end
end set
/-! ### Piecewise defined function -/
namespace set
variables {δ : α → Sort y} (s : set α) (f g : Πi, δ i)
@[simp] lemma piecewise_empty [∀i : α, decidable (i ∈ (∅ : set α))] : piecewise ∅ f g = g :=
by { ext i, simp [piecewise] }
@[simp] lemma piecewise_univ [∀i : α, decidable (i ∈ (set.univ : set α))] :
piecewise set.univ f g = f :=
by { ext i, simp [piecewise] }
@[simp] lemma piecewise_insert_self {j : α} [∀i, decidable (i ∈ insert j s)] :
(insert j s).piecewise f g j = f j :=
by simp [piecewise]
variable [∀j, decidable (j ∈ s)]
lemma piecewise_insert [decidable_eq α] (j : α) [∀i, decidable (i ∈ insert j s)] :
(insert j s).piecewise f g = function.update (s.piecewise f g) j (f j) :=
begin
simp [piecewise],
ext i,
by_cases h : i = j,
{ rw h, simp },
{ by_cases h' : i ∈ s; simp [h, h'] }
end
@[simp, priority 990]
lemma piecewise_eq_of_mem {i : α} (hi : i ∈ s) : s.piecewise f g i = f i :=
by simp [piecewise, hi]
@[simp, priority 990]
lemma piecewise_eq_of_not_mem {i : α} (hi : i ∉ s) : s.piecewise f g i = g i :=
by simp [piecewise, hi]
@[simp, priority 990]
lemma piecewise_insert_of_ne {i j : α} (h : i ≠ j) [∀i, decidable (i ∈ insert j s)] :
(insert j s).piecewise f g i = s.piecewise f g i :=
by simp [piecewise, h]
end set
namespace function
open set
variables {fa : α → α} {fb : β → β} {f : α → β} {g : β → γ} {s t : set α}
lemma injective.inj_on (h : injective f) (s : set α) : s.inj_on f :=
λ _ _ _ _ heq, h heq
lemma injective.comp_inj_on (hg : injective g) (hf : s.inj_on f) : s.inj_on (g ∘ f) :=
(hg.inj_on univ).comp hf (maps_to_univ _ _)
lemma surjective.surj_on (hf : surjective f) (s : set β) :
surj_on f univ s :=
(surjective_iff_surj_on_univ.1 hf).mono (subset.refl _) (subset_univ _)
namespace semiconj
lemma maps_to_image (h : semiconj f fa fb) (ha : maps_to fa s t) :
maps_to fb (f '' s) (f '' t) :=
λ y ⟨x, hx, hy⟩, hy ▸ ⟨fa x, ha hx, h x⟩
lemma maps_to_range (h : semiconj f fa fb) : maps_to fb (range f) (range f) :=
λ y ⟨x, hy⟩, hy ▸ ⟨fa x, h x⟩
lemma surj_on_image (h : semiconj f fa fb) (ha : surj_on fa s t) :
surj_on fb (f '' s) (f '' t) :=
begin
rintros y ⟨x, hxt, rfl⟩,
rcases ha hxt with ⟨x, hxs, rfl⟩,
rw [h x],
exact mem_image_of_mem _ (mem_image_of_mem _ hxs)
end
lemma surj_on_range (h : semiconj f fa fb) (ha : surjective fa) :
surj_on fb (range f) (range f) :=
by { rw ← image_univ, exact h.surj_on_image (ha.surj_on univ) }
lemma inj_on_image (h : semiconj f fa fb) (ha : inj_on fa s) (hf : inj_on f (fa '' s)) :
inj_on fb (f '' s) :=
begin
rintros _ _ ⟨x, hx, rfl⟩ ⟨y, hy, rfl⟩ H,
simp only [← h.eq] at H,
exact congr_arg f (ha hx hy $ hf (mem_image_of_mem fa hx) (mem_image_of_mem fa hy) H)
end
lemma inj_on_range (h : semiconj f fa fb) (ha : injective fa) (hf : inj_on f (range fa)) :
inj_on fb (range f) :=
by { rw ← image_univ at *, exact h.inj_on_image (ha.inj_on univ) hf }
lemma bij_on_image (h : semiconj f fa fb) (ha : bij_on fa s t) (hf : inj_on f t) :
bij_on fb (f '' s) (f '' t) :=
⟨h.maps_to_image ha.maps_to, h.inj_on_image ha.inj_on (ha.image_eq.symm ▸ hf),
h.surj_on_image ha.surj_on⟩
lemma bij_on_range (h : semiconj f fa fb) (ha : bijective fa) (hf : injective f) :
bij_on fb (range f) (range f) :=
begin
rw [← image_univ],
exact h.bij_on_image (bijective_iff_bij_on_univ.1 ha) (hf.inj_on univ)
end
lemma maps_to_preimage (h : semiconj f fa fb) {s t : set β} (hb : maps_to fb s t) :
maps_to fa (f ⁻¹' s) (f ⁻¹' t) :=
λ x hx, by simp only [mem_preimage, h x, hb hx]
lemma inj_on_preimage (h : semiconj f fa fb) {s : set β} (hb : inj_on fb s)
(hf : inj_on f (f ⁻¹' s)) :
inj_on fa (f ⁻¹' s) :=
begin
intros x y hx hy H,
have := congr_arg f H,
rw [h.eq, h.eq] at this,
exact hf hx hy (hb hx hy this)
end
end semiconj
lemma update_comp_eq_of_not_mem_range [decidable_eq β]
(g : β → γ) {f : α → β} {i : β} (a : γ) (h : i ∉ set.range f) :
(function.update g i a) ∘ f = g ∘ f :=
begin
ext p,
have : f p ≠ i,
{ by_contradiction H,
push_neg at H,
rw ← H at h,
exact h (set.mem_range_self _) },
simp [this],
end
lemma update_comp_eq_of_injective [decidable_eq α] [decidable_eq β]
(g : β → γ) {f : α → β} (hf : function.injective f) (i : α) (a : γ) :
(function.update g (f i) a) ∘ f = function.update (g ∘ f) i a :=
begin
ext j,
by_cases h : j = i,
{ rw h, simp },
{ have : f j ≠ f i := hf.ne h,
simp [h, this] }
end
end function
|
f868811273e93659128e6bfcf0ac773809552ac6 | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /src/Init/Data/Array/BasicAux.lean | 1f8285b4992f01f71ec5805b748e0149275557e6 | [
"Apache-2.0",
"LLVM-exception",
"NCSA",
"LGPL-3.0-only",
"LicenseRef-scancode-inner-net-2.0",
"BSD-3-Clause",
"LGPL-2.0-or-later",
"Spencer-94",
"LGPL-2.1-or-later",
"HPND",
"LicenseRef-scancode-pcre",
"ISC",
"LGPL-2.1-only",
"LicenseRef-scancode-other-permissive",
"SunPro",
"CMU-Mach"... | permissive | leanprover/lean4 | 4bdf9790294964627eb9be79f5e8f6157780b4cc | f1f9dc0f2f531af3312398999d8b8303fa5f096b | refs/heads/master | 1,693,360,665,786 | 1,693,350,868,000 | 1,693,350,868,000 | 129,571,436 | 2,827 | 311 | Apache-2.0 | 1,694,716,156,000 | 1,523,760,560,000 | Lean | UTF-8 | Lean | false | false | 2,955 | lean | /-
Copyright (c) 2022 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
prelude
import Init.Data.Array.Basic
import Init.Data.Nat.Linear
import Init.NotationExtra
theorem Array.of_push_eq_push {as bs : Array α} (h : as.push a = bs.push b) : as = bs ∧ a = b := by
simp [push] at h
have ⟨h₁, h₂⟩ := List.of_concat_eq_concat h
cases as; cases bs
simp_all
private theorem List.size_toArrayAux (as : List α) (bs : Array α) : (as.toArrayAux bs).size = as.length + bs.size := by
induction as generalizing bs with
| nil => simp [toArrayAux]
| cons a as ih => simp_arith [toArrayAux, *]
private theorem List.of_toArrayAux_eq_toArrayAux {as bs : List α} {cs ds : Array α} (h : as.toArrayAux cs = bs.toArrayAux ds) (hlen : cs.size = ds.size) : as = bs ∧ cs = ds := by
match as, bs with
| [], [] => simp [toArrayAux] at h; simp [h]
| a::as, [] => simp [toArrayAux] at h; rw [← h] at hlen; simp_arith [size_toArrayAux] at hlen
| [], b::bs => simp [toArrayAux] at h; rw [h] at hlen; simp_arith [size_toArrayAux] at hlen
| a::as, b::bs =>
simp [toArrayAux] at h
have : (cs.push a).size = (ds.push b).size := by simp [*]
have ⟨ih₁, ih₂⟩ := of_toArrayAux_eq_toArrayAux h this
simp [ih₁]
have := Array.of_push_eq_push ih₂
simp [this]
@[simp] theorem List.toArray_eq_toArray_eq (as bs : List α) : (as.toArray = bs.toArray) = (as = bs) := by
apply propext; apply Iff.intro
· intro h; simp [toArray] at h; have := of_toArrayAux_eq_toArrayAux h rfl; exact this.1
· intro h; rw [h]
def Array.mapM' [Monad m] (f : α → m β) (as : Array α) : m { bs : Array β // bs.size = as.size } :=
go 0 ⟨mkEmpty as.size, rfl⟩ (by simp_arith)
where
go (i : Nat) (acc : { bs : Array β // bs.size = i }) (hle : i ≤ as.size) : m { bs : Array β // bs.size = as.size } := do
if h : i = as.size then
return h ▸ acc
else
have hlt : i < as.size := Nat.lt_of_le_of_ne hle h
let b ← f as[i]
go (i+1) ⟨acc.val.push b, by simp [acc.property]⟩ hlt
termination_by go i _ _ => as.size - i
@[inline] private unsafe def mapMonoMImp [Monad m] (as : Array α) (f : α → m α) : m (Array α) :=
go 0 as
where
@[specialize] go (i : Nat) (as : Array α) : m (Array α) := do
if h : i < as.size then
let a := as[i]
let b ← f a
if ptrEq a b then
go (i+1) as
else
go (i+1) (as.set ⟨i, h⟩ b)
else
return as
/--
Monomorphic `Array.mapM`. The internal implementation uses pointer equality, and does not allocate a new array
if the result of each `f a` is a pointer equal value `a`.
-/
@[implemented_by mapMonoMImp] def Array.mapMonoM [Monad m] (as : Array α) (f : α → m α) : m (Array α) :=
as.mapM f
@[inline] def Array.mapMono (as : Array α) (f : α → α) : Array α :=
Id.run <| as.mapMonoM f
|
824694cffe73e42aeed7a562b1af1e8357dfb609 | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/category_theory/extensive.lean | 9a7349ba8495fd7409e5c3bc9697a575bcd2a6a0 | [
"Apache-2.0"
] | permissive | leanprover-community/mathlib | 56a2cadd17ac88caf4ece0a775932fa26327ba0e | 442a83d738cb208d3600056c489be16900ba701d | refs/heads/master | 1,693,584,102,358 | 1,693,471,902,000 | 1,693,471,902,000 | 97,922,418 | 1,595 | 352 | Apache-2.0 | 1,694,693,445,000 | 1,500,624,130,000 | Lean | UTF-8 | Lean | false | false | 25,330 | lean | /-
Copyright (c) 2022 Andrew Yang. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Andrew Yang
-/
import category_theory.limits.shapes.comm_sq
import category_theory.limits.shapes.strict_initial
import category_theory.limits.shapes.types
import topology.category.Top.limits.pullbacks
import category_theory.limits.functor_category
/-!
# Extensive categories
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
## Main definitions
- `category_theory.is_van_kampen_colimit`: A (colimit) cocone over a diagram `F : J ⥤ C` is van
Kampen if for every cocone `c'` over the pullback of the diagram `F' : J ⥤ C'`,
`c'` is colimiting iff `c'` is the pullback of `c`.
- `category_theory.finitary_extensive`: A category is (finitary) extensive if it has finite
coproducts, and binary coproducts are van Kampen.
## Main Results
- `category_theory.has_strict_initial_objects_of_finitary_extensive`: The initial object
in extensive categories is strict.
- `category_theory.finitary_extensive.mono_inr_of_is_colimit`: Coproduct injections are monic in
extensive categories.
- `category_theory.binary_cofan.is_pullback_initial_to_of_is_van_kampen`: In extensive categories,
sums are disjoint, i.e. the pullback of `X ⟶ X ⨿ Y` and `Y ⟶ X ⨿ Y` is the initial object.
- `category_theory.types.finitary_extensive`: The category of types is extensive.
## TODO
Show that the following are finitary extensive:
- the categories of sheaves over a site
- `Scheme`
- `AffineScheme` (`CommRingᵒᵖ`)
## References
- https://ncatlab.org/nlab/show/extensive+category
- [Carboni et al, Introduction to extensive and distributive categories][CARBONI1993145]
-/
open category_theory.limits
namespace category_theory
universes v' u' v u
variables {J : Type v'} [category.{u'} J] {C : Type u} [category.{v} C]
/-- A natural transformation is equifibered if every commutative square of the following form is
a pullback.
```
F(X) → F(Y)
↓ ↓
G(X) → G(Y)
```
-/
def nat_trans.equifibered {F G : J ⥤ C} (α : F ⟶ G) : Prop :=
∀ ⦃i j : J⦄ (f : i ⟶ j), is_pullback (F.map f) (α.app i) (α.app j) (G.map f)
lemma nat_trans.equifibered_of_is_iso {F G : J ⥤ C} (α : F ⟶ G) [is_iso α] : α.equifibered :=
λ _ _ f, is_pullback.of_vert_is_iso ⟨nat_trans.naturality _ f⟩
lemma nat_trans.equifibered.comp {F G H : J ⥤ C} {α : F ⟶ G} {β : G ⟶ H}
(hα : α.equifibered) (hβ : β.equifibered) : (α ≫ β).equifibered :=
λ i j f, (hα f).paste_vert (hβ f)
/-- A (colimit) cocone over a diagram `F : J ⥤ C` is universal if it is stable under pullbacks. -/
def is_universal_colimit {F : J ⥤ C} (c : cocone F) : Prop :=
∀ ⦃F' : J ⥤ C⦄ (c' : cocone F') (α : F' ⟶ F) (f : c'.X ⟶ c.X)
(h : α ≫ c.ι = c'.ι ≫ (functor.const J).map f) (hα : α.equifibered),
(∀ j : J, is_pullback (c'.ι.app j) (α.app j) f (c.ι.app j)) → nonempty (is_colimit c')
/-- A (colimit) cocone over a diagram `F : J ⥤ C` is van Kampen if for every cocone `c'` over the
pullback of the diagram `F' : J ⥤ C'`, `c'` is colimiting iff `c'` is the pullback of `c`.
TODO: Show that this is iff the functor `C ⥤ Catᵒᵖ` sending `x` to `C/x` preserves it.
TODO: Show that this is iff the inclusion functor `C ⥤ Span(C)` preserves it.
-/
def is_van_kampen_colimit {F : J ⥤ C} (c : cocone F) : Prop :=
∀ ⦃F' : J ⥤ C⦄ (c' : cocone F') (α : F' ⟶ F) (f : c'.X ⟶ c.X)
(h : α ≫ c.ι = c'.ι ≫ (functor.const J).map f) (hα : α.equifibered),
nonempty (is_colimit c') ↔ ∀ j : J, is_pullback (c'.ι.app j) (α.app j) f (c.ι.app j)
lemma is_van_kampen_colimit.is_universal {F : J ⥤ C} {c : cocone F} (H : is_van_kampen_colimit c) :
is_universal_colimit c :=
λ _ c' α f h hα, (H c' α f h hα).mpr
/-- A van Kampen colimit is a colimit. -/
noncomputable
def is_van_kampen_colimit.is_colimit {F : J ⥤ C} {c : cocone F} (h : is_van_kampen_colimit c) :
is_colimit c :=
begin
refine ((h c (𝟙 F) (𝟙 c.X : _) (by rw [functor.map_id, category.comp_id, category.id_comp])
(nat_trans.equifibered_of_is_iso _)).mpr $ λ j, _).some,
haveI : is_iso (𝟙 c.X) := infer_instance,
exact is_pullback.of_vert_is_iso ⟨by erw [nat_trans.id_app, category.comp_id, category.id_comp]⟩,
end
lemma is_initial.is_van_kampen_colimit [has_strict_initial_objects C] {X : C} (h : is_initial X) :
is_van_kampen_colimit (as_empty_cocone X) :=
begin
intros F' c' α f hf hα,
have : F' = functor.empty C := by apply functor.hext; rintro ⟨⟨⟩⟩,
subst this,
haveI := h.is_iso_to f,
refine ⟨by rintro _ ⟨⟨⟩⟩, λ _,
⟨is_colimit.of_iso_colimit h (cocones.ext (as_iso f).symm $ by rintro ⟨⟨⟩⟩)⟩⟩
end
section extensive
variables {X Y : C}
/--
A category is (finitary) extensive if it has finite coproducts,
and binary coproducts are van Kampen.
TODO: Show that this is iff all finite coproducts are van Kampen. -/
class finitary_extensive (C : Type u) [category.{v} C] : Prop :=
[has_finite_coproducts : has_finite_coproducts C]
(van_kampen' : ∀ {X Y : C} (c : binary_cofan X Y), is_colimit c → is_van_kampen_colimit c)
attribute [priority 100, instance] finitary_extensive.has_finite_coproducts
lemma finitary_extensive.van_kampen [finitary_extensive C] {F : discrete walking_pair ⥤ C}
(c : cocone F) (hc : is_colimit c) : is_van_kampen_colimit c :=
begin
let X := F.obj ⟨walking_pair.left⟩, let Y := F.obj ⟨walking_pair.right⟩,
have : F = pair X Y,
{ apply functor.hext, { rintros ⟨⟨⟩⟩; refl }, { rintros ⟨⟨⟩⟩ ⟨j⟩ ⟨⟨rfl : _ = j⟩⟩; simpa } },
clear_value X Y, subst this,
exact finitary_extensive.van_kampen' c hc
end
lemma map_pair_equifibered {F F' : discrete walking_pair ⥤ C} (α : F ⟶ F') : α.equifibered :=
begin
rintros ⟨⟨⟩⟩ ⟨j⟩ ⟨⟨rfl : _ = j⟩⟩,
all_goals { dsimp, simp only [discrete.functor_map_id],
exact is_pullback.of_horiz_is_iso ⟨by simp only [category.comp_id, category.id_comp]⟩ }
end
lemma binary_cofan.is_van_kampen_iff (c : binary_cofan X Y) :
is_van_kampen_colimit c ↔
∀ {X' Y' : C} (c' : binary_cofan X' Y') (αX : X' ⟶ X) (αY : Y' ⟶ Y)
(f : c'.X ⟶ c.X) (hαX : αX ≫ c.inl = c'.inl ≫ f) (hαY : αY ≫ c.inr = c'.inr ≫ f),
nonempty (is_colimit c') ↔ is_pullback c'.inl αX f c.inl ∧ is_pullback c'.inr αY f c.inr :=
begin
split,
{ introv H hαX hαY,
rw H c' (map_pair αX αY) f (by ext ⟨⟨⟩⟩; dsimp; assumption) (map_pair_equifibered _),
split, { intro H, exact ⟨H _, H _⟩ }, { rintros H ⟨⟨⟩⟩, exacts [H.1, H.2] } },
{ introv H F' hα h,
let X' := F'.obj ⟨walking_pair.left⟩, let Y' := F'.obj ⟨walking_pair.right⟩,
have : F' = pair X' Y',
{ apply functor.hext, { rintros ⟨⟨⟩⟩; refl }, { rintros ⟨⟨⟩⟩ ⟨j⟩ ⟨⟨rfl : _ = j⟩⟩; simpa } },
clear_value X' Y', subst this, change binary_cofan X' Y' at c',
rw H c' _ _ _ (nat_trans.congr_app hα ⟨walking_pair.left⟩)
(nat_trans.congr_app hα ⟨walking_pair.right⟩),
split, { rintros H ⟨⟨⟩⟩, exacts [H.1, H.2] }, { intro H, exact ⟨H _, H _⟩ } }
end
lemma binary_cofan.is_van_kampen_mk {X Y : C} (c : binary_cofan X Y)
(cofans : ∀ (X Y : C), binary_cofan X Y) (colimits : ∀ X Y, is_colimit (cofans X Y))
(cones : ∀ {X Y Z : C} (f : X ⟶ Z) (g : Y ⟶ Z), pullback_cone f g)
(limits : ∀ {X Y Z : C} (f : X ⟶ Z) (g : Y ⟶ Z), is_limit (cones f g))
(h₁ : ∀ {X' Y' : C} (αX : X' ⟶ X) (αY : Y' ⟶ Y) (f : (cofans X' Y').X ⟶ c.X)
(hαX : αX ≫ c.inl = (cofans X' Y').inl ≫ f) (hαY : αY ≫ c.inr = (cofans X' Y').inr ≫ f),
is_pullback (cofans X' Y').inl αX f c.inl ∧ is_pullback (cofans X' Y').inr αY f c.inr)
(h₂ : ∀ {Z : C} (f : Z ⟶ c.X),
is_colimit (binary_cofan.mk (cones f c.inl).fst (cones f c.inr).fst)) :
is_van_kampen_colimit c :=
begin
rw binary_cofan.is_van_kampen_iff,
introv hX hY,
split,
{ rintros ⟨h⟩,
let e := h.cocone_point_unique_up_to_iso (colimits _ _),
obtain ⟨hl, hr⟩ := h₁ αX αY (e.inv ≫ f) (by simp [hX]) (by simp [hY]),
split,
{ rw [← category.id_comp αX, ← iso.hom_inv_id_assoc e f],
have : c'.inl ≫ e.hom = 𝟙 X' ≫ (cofans X' Y').inl := by { dsimp, simp },
haveI : is_iso (𝟙 X') := infer_instance,
exact (is_pullback.of_vert_is_iso ⟨this⟩).paste_vert hl },
{ rw [← category.id_comp αY, ← iso.hom_inv_id_assoc e f],
have : c'.inr ≫ e.hom = 𝟙 Y' ≫ (cofans X' Y').inr := by { dsimp, simp },
haveI : is_iso (𝟙 Y') := infer_instance,
exact (is_pullback.of_vert_is_iso ⟨this⟩).paste_vert hr } },
{ rintro ⟨H₁, H₂⟩,
refine ⟨is_colimit.of_iso_colimit _ $ (iso_binary_cofan_mk _).symm⟩,
let e₁ : X' ≅ _ := H₁.is_limit.cone_point_unique_up_to_iso (limits _ _),
let e₂ : Y' ≅ _ := H₂.is_limit.cone_point_unique_up_to_iso (limits _ _),
have he₁ : c'.inl = e₁.hom ≫ (cones f c.inl).fst := by simp,
have he₂ : c'.inr = e₂.hom ≫ (cones f c.inr).fst := by simp,
rw [he₁, he₂],
apply binary_cofan.is_colimit_comp_right_iso (binary_cofan.mk _ _),
apply binary_cofan.is_colimit_comp_left_iso (binary_cofan.mk _ _),
exact h₂ f }
end
.
lemma binary_cofan.mono_inr_of_is_van_kampen [has_initial C] {X Y : C} {c : binary_cofan X Y}
(h : is_van_kampen_colimit c) : mono c.inr :=
begin
refine pullback_cone.mono_of_is_limit_mk_id_id _ (is_pullback.is_limit _),
refine (h (binary_cofan.mk (initial.to Y) (𝟙 Y))
(map_pair (initial.to X) (𝟙 Y)) c.inr _ (map_pair_equifibered _)).mp ⟨_⟩ ⟨walking_pair.right⟩,
{ ext ⟨⟨⟩⟩; dsimp; simp },
{ exact ((binary_cofan.is_colimit_iff_is_iso_inr initial_is_initial _).mpr
(by { dsimp, apply_instance })).some }
end
lemma finitary_extensive.mono_inr_of_is_colimit [finitary_extensive C]
{c : binary_cofan X Y} (hc : is_colimit c) : mono c.inr :=
binary_cofan.mono_inr_of_is_van_kampen (finitary_extensive.van_kampen c hc)
lemma finitary_extensive.mono_inl_of_is_colimit [finitary_extensive C]
{c : binary_cofan X Y} (hc : is_colimit c) : mono c.inl :=
finitary_extensive.mono_inr_of_is_colimit (binary_cofan.is_colimit_flip hc)
instance [finitary_extensive C] (X Y : C) : mono (coprod.inl : X ⟶ X ⨿ Y) :=
(finitary_extensive.mono_inl_of_is_colimit (coprod_is_coprod X Y) : _)
instance [finitary_extensive C] (X Y : C) : mono (coprod.inr : Y ⟶ X ⨿ Y) :=
(finitary_extensive.mono_inr_of_is_colimit (coprod_is_coprod X Y) : _)
lemma binary_cofan.is_pullback_initial_to_of_is_van_kampen [has_initial C]
{c : binary_cofan X Y}
(h : is_van_kampen_colimit c) : is_pullback (initial.to _) (initial.to _) c.inl c.inr :=
begin
refine ((h (binary_cofan.mk (initial.to Y) (𝟙 Y)) (map_pair (initial.to X) (𝟙 Y)) c.inr _
(map_pair_equifibered _)).mp ⟨_⟩ ⟨walking_pair.left⟩).flip,
{ ext ⟨⟨⟩⟩; dsimp; simp },
{ exact ((binary_cofan.is_colimit_iff_is_iso_inr initial_is_initial _).mpr
(by { dsimp, apply_instance })).some }
end
lemma finitary_extensive.is_pullback_initial_to_binary_cofan [finitary_extensive C]
{c : binary_cofan X Y} (hc : is_colimit c) :
is_pullback (initial.to _) (initial.to _) c.inl c.inr :=
binary_cofan.is_pullback_initial_to_of_is_van_kampen (finitary_extensive.van_kampen c hc)
lemma has_strict_initial_of_is_universal [has_initial C]
(H : is_universal_colimit (binary_cofan.mk (𝟙 (⊥_ C)) (𝟙 (⊥_ C)))) :
has_strict_initial_objects C :=
has_strict_initial_objects_of_initial_is_strict
begin
intros A f,
suffices : is_colimit (binary_cofan.mk (𝟙 A) (𝟙 A)),
{ obtain ⟨l, h₁, h₂⟩ := limits.binary_cofan.is_colimit.desc' this (f ≫ initial.to A) (𝟙 A),
rcases (category.id_comp _).symm.trans h₂ with rfl,
exact ⟨⟨_, ((category.id_comp _).symm.trans h₁).symm, initial_is_initial.hom_ext _ _⟩⟩ },
refine (H (binary_cofan.mk (𝟙 _) (𝟙 _)) (map_pair f f) f (by ext ⟨⟨⟩⟩; dsimp; simp)
(map_pair_equifibered _) _).some,
rintro ⟨⟨⟩⟩; dsimp;
exact is_pullback.of_horiz_is_iso ⟨(category.id_comp _).trans (category.comp_id _).symm⟩
end
@[priority 100]
instance has_strict_initial_objects_of_finitary_extensive [finitary_extensive C] :
has_strict_initial_objects C :=
has_strict_initial_of_is_universal (finitary_extensive.van_kampen _
((binary_cofan.is_colimit_iff_is_iso_inr initial_is_initial _).mpr
(by { dsimp, apply_instance })).some).is_universal
lemma finitary_extensive_iff_of_is_terminal (C : Type u) [category.{v} C] [has_finite_coproducts C]
(T : C) (HT : is_terminal T) (c₀ : binary_cofan T T) (hc₀ : is_colimit c₀) :
finitary_extensive C ↔ is_van_kampen_colimit c₀ :=
begin
refine ⟨λ H, H.2 c₀ hc₀, λ H, _⟩,
constructor,
simp_rw binary_cofan.is_van_kampen_iff at H ⊢,
intros X Y c hc X' Y' c' αX αY f hX hY,
obtain ⟨d, hd, hd'⟩ := limits.binary_cofan.is_colimit.desc' hc
(HT.from _ ≫ c₀.inl) (HT.from _ ≫ c₀.inr),
rw H c' (αX ≫ HT.from _) (αY ≫ HT.from _) (f ≫ d)
(by rw [← reassoc_of hX, hd, category.assoc])
(by rw [← reassoc_of hY, hd', category.assoc]),
obtain ⟨hl, hr⟩ := (H c (HT.from _) (HT.from _) d hd.symm hd'.symm).mp ⟨hc⟩,
rw [hl.paste_vert_iff hX.symm, hr.paste_vert_iff hY.symm]
end
instance types.finitary_extensive : finitary_extensive (Type u) :=
begin
rw [finitary_extensive_iff_of_is_terminal (Type u) punit types.is_terminal_punit _
(types.binary_coproduct_colimit _ _)],
apply binary_cofan.is_van_kampen_mk _ _ (λ X Y, types.binary_coproduct_colimit X Y) _
(λ X Y Z f g, (limits.types.pullback_limit_cone f g).2),
{ intros,
split,
{ refine ⟨⟨hαX.symm⟩, ⟨pullback_cone.is_limit_aux' _ _⟩⟩,
intro s,
have : ∀ x, ∃! y, s.fst x = sum.inl y,
{ intro x,
cases h : s.fst x,
{ simp_rw sum.inl_injective.eq_iff, exact exists_unique_eq' },
{ apply_fun f at h,
cases ((congr_fun s.condition x).symm.trans h).trans (congr_fun hαY val : _).symm } },
delta exists_unique at this,
choose l hl hl',
exact ⟨l, (funext hl).symm, types.is_terminal_punit.hom_ext _ _,
λ l' h₁ h₂, funext $ λ x, hl' x (l' x) (congr_fun h₁ x).symm⟩ },
{ refine ⟨⟨hαY.symm⟩, ⟨pullback_cone.is_limit_aux' _ _⟩⟩,
intro s, dsimp,
have : ∀ x, ∃! y, s.fst x = sum.inr y,
{ intro x,
cases h : s.fst x,
{ apply_fun f at h,
cases ((congr_fun s.condition x).symm.trans h).trans (congr_fun hαX val : _).symm },
{ simp_rw sum.inr_injective.eq_iff, exact exists_unique_eq' } },
delta exists_unique at this,
choose l hl hl',
exact ⟨l, (funext hl).symm, types.is_terminal_punit.hom_ext _ _,
λ l' h₁ h₂, funext $ λ x, hl' x (l' x) (congr_fun h₁ x).symm⟩ } },
{ intros Z f,
dsimp [limits.types.binary_coproduct_cocone],
delta types.pullback_obj,
have : ∀ x, f x = sum.inl punit.star ∨ f x = sum.inr punit.star,
{ intro x, rcases f x with (⟨⟨⟩⟩|⟨⟨⟩⟩), exacts [or.inl rfl, or.inr rfl] },
let eX : {p : Z × punit // f p.fst = sum.inl p.snd} ≃ {x : Z // f x = sum.inl punit.star } :=
⟨λ p, ⟨p.1.1, by convert p.2⟩, λ x, ⟨⟨_, _⟩, x.2⟩, λ _, by ext; refl, λ _, by ext; refl⟩,
let eY : {p : Z × punit // f p.fst = sum.inr p.snd} ≃ {x : Z // f x = sum.inr punit.star } :=
⟨λ p, ⟨p.1.1, p.2.trans (congr_arg sum.inr $ subsingleton.elim _ _)⟩,
λ x, ⟨⟨_, _⟩, x.2⟩, λ _, by ext; refl, λ _, by ext; refl⟩,
fapply binary_cofan.is_colimit_mk,
{ exact λ s x, dite _ (λ h, s.inl $ eX.symm ⟨x, h⟩)
(λ h, s.inr $ eY.symm ⟨x, (this x).resolve_left h⟩) },
{ intro s, ext ⟨⟨x, ⟨⟩⟩, _⟩, dsimp, split_ifs; refl },
{ intro s, ext ⟨⟨x, ⟨⟩⟩, hx⟩, dsimp, split_ifs, { cases h.symm.trans hx }, { refl } },
{ intros s m e₁ e₂, ext x, split_ifs, { rw ← e₁, refl }, { rw ← e₂, refl } } }
end
section Top
/-- (Implementation) An auxiliary lemma for the proof that `Top` is finitary extensive. -/
def finitary_extensive_Top_aux (Z : Top.{u}) (f : Z ⟶ Top.of (punit.{u+1} ⊕ punit.{u+1})) :
is_colimit (binary_cofan.mk
(Top.pullback_fst f (Top.binary_cofan (Top.of punit) (Top.of punit)).inl)
(Top.pullback_fst f (Top.binary_cofan (Top.of punit) (Top.of punit)).inr)) :=
begin
have : ∀ x, f x = sum.inl punit.star ∨ f x = sum.inr punit.star,
{ intro x, rcases f x with (⟨⟨⟩⟩|⟨⟨⟩⟩), exacts [or.inl rfl, or.inr rfl] },
let eX : {p : Z × punit // f p.fst = sum.inl p.snd} ≃ { x : Z // f x = sum.inl punit.star } :=
⟨λ p, ⟨p.1.1, p.2.trans (congr_arg sum.inl $ subsingleton.elim _ _)⟩,
λ x, ⟨⟨_, _⟩, x.2⟩, λ _, by ext; refl, λ _, by ext; refl⟩,
let eY : {p : Z × punit // f p.fst = sum.inr p.snd} ≃ { x : Z // f x = sum.inr punit.star } :=
⟨λ p, ⟨p.1.1, p.2.trans (congr_arg sum.inr $ subsingleton.elim _ _)⟩,
λ x, ⟨⟨_, _⟩, x.2⟩, λ _, by ext; refl, λ _, by ext; refl⟩,
fapply binary_cofan.is_colimit_mk,
{ refine λ s, ⟨λ x, dite _ (λ h, s.inl $ eX.symm ⟨x, h⟩)
(λ h, s.inr $ eY.symm ⟨x, (this x).resolve_left h⟩), _⟩,
rw continuous_iff_continuous_at,
intro x,
by_cases f x = sum.inl punit.star,
{ revert h x,
apply (is_open.continuous_on_iff _).mp,
{ rw continuous_on_iff_continuous_restrict,
convert_to continuous (λ x : {x|f x = sum.inl punit.star}, s.inl ⟨(x, punit.star), x.2⟩),
{ ext ⟨x, hx⟩, exact dif_pos hx },
continuity },
{ convert f.2.1 _ (open_embedding_inl).open_range, ext x, exact ⟨λ h, ⟨_, h.symm⟩,
λ ⟨e, h⟩, h.symm.trans (congr_arg sum.inl $ subsingleton.elim _ _)⟩ } },
{ revert h x,
apply (is_open.continuous_on_iff _).mp,
{ rw continuous_on_iff_continuous_restrict,
convert_to continuous (λ x : {x|f x ≠ sum.inl punit.star},
s.inr ⟨(x, punit.star), (this _).resolve_left x.2⟩),
{ ext ⟨x, hx⟩, exact dif_neg hx },
continuity },
{ convert f.2.1 _ (open_embedding_inr).open_range, ext x,
change f x ≠ sum.inl punit.star ↔ f x ∈ set.range sum.inr,
transitivity f x = sum.inr punit.star,
{ rcases f x with (⟨⟨⟩⟩|⟨⟨⟩⟩);
simp only [iff_self, eq_self_iff_true, not_true, ne.def, not_false_iff] },
{ exact ⟨λ h, ⟨_, h.symm⟩, λ ⟨e, h⟩,
h.symm.trans (congr_arg sum.inr $ subsingleton.elim _ _)⟩ } } } },
{ intro s, ext ⟨⟨x, ⟨⟩⟩, _⟩, change dite _ _ _ = _, split_ifs; refl },
{ intro s, ext ⟨⟨x, ⟨⟩⟩, hx⟩, change dite _ _ _ = _,
split_ifs, { cases h.symm.trans hx }, { refl } },
{ intros s m e₁ e₂, ext x, change m x = dite _ _ _,
split_ifs, { rw ← e₁, refl }, { rw ← e₂, refl } }
end
instance : finitary_extensive Top.{u} :=
begin
rw [finitary_extensive_iff_of_is_terminal Top.{u} _ Top.is_terminal_punit _
(Top.binary_cofan_is_colimit _ _)],
apply binary_cofan.is_van_kampen_mk _ _ (λ X Y, Top.binary_cofan_is_colimit X Y) _
(λ X Y Z f g, Top.pullback_cone_is_limit f g),
{ intros,
split,
{ refine ⟨⟨hαX.symm⟩, ⟨pullback_cone.is_limit_aux' _ _⟩⟩,
intro s,
have : ∀ x, ∃! y, s.fst x = sum.inl y,
{ intro x,
cases h : s.fst x,
{ simp_rw sum.inl_injective.eq_iff, exact exists_unique_eq' },
{ apply_fun f at h,
cases ((concrete_category.congr_hom s.condition x).symm.trans h).trans
(concrete_category.congr_hom hαY val : _).symm } },
delta exists_unique at this,
choose l hl hl',
refine ⟨⟨l, _⟩, continuous_map.ext (λ a, (hl a).symm), Top.is_terminal_punit.hom_ext _ _,
λ l' h₁ h₂, continuous_map.ext $ λ x,
hl' x (l' x) (concrete_category.congr_hom h₁ x).symm⟩,
apply embedding_inl.to_inducing.continuous_iff.mpr,
convert s.fst.2 using 1, exact (funext hl).symm },
{ refine ⟨⟨hαY.symm⟩, ⟨pullback_cone.is_limit_aux' _ _⟩⟩,
intro s, dsimp,
have : ∀ x, ∃! y, s.fst x = sum.inr y,
{ intro x,
cases h : s.fst x,
{ apply_fun f at h,
cases ((concrete_category.congr_hom s.condition x).symm.trans h).trans
(concrete_category.congr_hom hαX val : _).symm },
{ simp_rw sum.inr_injective.eq_iff, exact exists_unique_eq' } },
delta exists_unique at this,
choose l hl hl',
refine ⟨⟨l, _⟩, continuous_map.ext (λ a, (hl a).symm), Top.is_terminal_punit.hom_ext _ _,
λ l' h₁ h₂, continuous_map.ext $
λ x, hl' x (l' x) (concrete_category.congr_hom h₁ x).symm⟩,
apply embedding_inr.to_inducing.continuous_iff.mpr,
convert s.fst.2 using 1, exact (funext hl).symm } },
{ intros Z f, exact finitary_extensive_Top_aux Z f }
end
end Top
section functor
universes v'' u''
variables {D : Type u''} [category.{v''} D]
lemma nat_trans.equifibered.whisker_right {F G : J ⥤ C} {α : F ⟶ G} (hα : α.equifibered)
(H : C ⥤ D) [preserves_limits_of_shape walking_cospan H] : (whisker_right α H).equifibered :=
λ i j f, (hα f).map H
lemma is_van_kampen_colimit.of_iso {F : J ⥤ C} {c c' : cocone F} (H : is_van_kampen_colimit c)
(e : c ≅ c') : is_van_kampen_colimit c' :=
begin
intros F' c'' α f h hα,
have : c'.ι ≫ (functor.const J).map e.inv.hom = c.ι,
{ ext j, exact e.inv.2 j },
rw H c'' α (f ≫ e.inv.1) (by rw [functor.map_comp, ← reassoc_of h, this]) hα,
apply forall_congr,
intro j,
conv_lhs { rw [← category.comp_id (α.app j)] },
haveI : is_iso e.inv.hom := functor.map_is_iso (cocones.forget _) e.inv,
exact (is_pullback.of_vert_is_iso ⟨by simp⟩).paste_vert_iff (nat_trans.congr_app h j).symm
end
lemma is_van_kampen_colimit.of_map {D : Type*} [category D] (G : C ⥤ D) {F : J ⥤ C} {c : cocone F}
[preserves_limits_of_shape walking_cospan G] [reflects_limits_of_shape walking_cospan G]
[preserves_colimits_of_shape J G] [reflects_colimits_of_shape J G]
(H : is_van_kampen_colimit (G.map_cocone c)) : is_van_kampen_colimit c :=
begin
intros F' c' α f h hα,
refine (iff.trans _ (H (G.map_cocone c') (whisker_right α G) (G.map f)
(by { ext j, simpa using G.congr_map (nat_trans.congr_app h j) })
(hα.whisker_right G))).trans (forall_congr $ λ j, _),
{ exact ⟨λ h, ⟨is_colimit_of_preserves G h.some⟩, λ h, ⟨is_colimit_of_reflects G h.some⟩⟩ },
{ exact is_pullback.map_iff G (nat_trans.congr_app h.symm j) }
end
lemma is_van_kampen_colimit_of_evaluation [has_pullbacks D] [has_colimits_of_shape J D]
(F : J ⥤ C ⥤ D) (c : cocone F)
(hc : ∀ x : C, is_van_kampen_colimit (((evaluation C D).obj x).map_cocone c)) :
is_van_kampen_colimit c :=
begin
intros F' c' α f e hα,
have := λ x, hc x (((evaluation C D).obj x).map_cocone c') (whisker_right α _)
(((evaluation C D).obj x).map f)
(by { ext y, dsimp, exact nat_trans.congr_app (nat_trans.congr_app e y) x })
(hα.whisker_right _),
split,
{ rintros ⟨hc'⟩ j,
refine ⟨⟨(nat_trans.congr_app e j).symm⟩, ⟨evaluation_jointly_reflects_limits _ _⟩⟩,
refine λ x, (is_limit_map_cone_pullback_cone_equiv _ _).symm _,
exact ((this x).mp ⟨preserves_colimit.preserves hc'⟩ _).is_limit },
{ exact λ H, ⟨evaluation_jointly_reflects_colimits _
(λ x, ((this x).mpr (λ j, (H j).map ((evaluation C D).obj x))).some)⟩ }
end
instance [has_pullbacks C] [finitary_extensive C] : finitary_extensive (D ⥤ C) :=
begin
haveI : has_finite_coproducts (D ⥤ C) := ⟨λ n, limits.functor_category_has_colimits_of_shape⟩,
exact ⟨λ X Y c hc, is_van_kampen_colimit_of_evaluation _ c
(λ x, finitary_extensive.van_kampen _ $ preserves_colimit.preserves hc)⟩
end
lemma finitary_extensive_of_preserves_and_reflects (F : C ⥤ D)
[finitary_extensive D] [has_finite_coproducts C]
[preserves_limits_of_shape walking_cospan F]
[reflects_limits_of_shape walking_cospan F]
[preserves_colimits_of_shape (discrete walking_pair) F]
[reflects_colimits_of_shape (discrete walking_pair) F] :
finitary_extensive C :=
⟨λ X Y c hc, (finitary_extensive.van_kampen _ (is_colimit_of_preserves F hc)).of_map F⟩
lemma finitary_extensive_of_preserves_and_reflects_isomorphism (F : C ⥤ D)
[finitary_extensive D] [has_finite_coproducts C] [has_pullbacks C]
[preserves_limits_of_shape walking_cospan F]
[preserves_colimits_of_shape (discrete walking_pair) F]
[reflects_isomorphisms F] :
finitary_extensive C :=
begin
haveI : reflects_limits_of_shape walking_cospan F :=
reflects_limits_of_shape_of_reflects_isomorphisms,
haveI : reflects_colimits_of_shape (discrete walking_pair) F :=
reflects_colimits_of_shape_of_reflects_isomorphisms,
exact finitary_extensive_of_preserves_and_reflects F,
end
end functor
end extensive
end category_theory
|
45a267b5e6428e9eb3da3ec8aa33d91eabee2ce2 | 957a80ea22c5abb4f4670b250d55534d9db99108 | /library/data/buffer.lean | ea721d58da49f320572d4c684d67143778ad0db8 | [
"Apache-2.0"
] | permissive | GaloisInc/lean | aa1e64d604051e602fcf4610061314b9a37ab8cd | f1ec117a24459b59c6ff9e56a1d09d9e9e60a6c0 | refs/heads/master | 1,592,202,909,807 | 1,504,624,387,000 | 1,504,624,387,000 | 75,319,626 | 2 | 1 | Apache-2.0 | 1,539,290,164,000 | 1,480,616,104,000 | C++ | UTF-8 | Lean | false | false | 4,225 | lean | /-
Copyright (c) 2017 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
universes u w
def buffer (α : Type u) := Σ n, array α n
def mk_buffer {α : Type u} : buffer α :=
⟨0, {data := λ i, fin.elim0 i}⟩
def array.to_buffer {α : Type u} {n : nat} (a : array α n) : buffer α :=
⟨n, a⟩
namespace buffer
variables {α : Type u} {β : Type w}
def nil : buffer α :=
mk_buffer
def size (b : buffer α) : nat :=
b.1
def to_array (b : buffer α) : array α (b.size) :=
b.2
def push_back : buffer α → α → buffer α
| ⟨n, a⟩ v := ⟨n+1, a.push_back v⟩
def pop_back : buffer α → buffer α
| ⟨0, a⟩ := ⟨0, a⟩
| ⟨n+1, a⟩ := ⟨n, a.pop_back⟩
def read : Π (b : buffer α), fin b.size → α
| ⟨n, a⟩ i := a.read i
def write : Π (b : buffer α), fin b.size → α → buffer α
| ⟨n, a⟩ i v := ⟨n, a.write i v⟩
def read' [inhabited α] : buffer α → nat → α
| ⟨n, a⟩ i := a.read' i
def write' : buffer α → nat → α → buffer α
| ⟨n, a⟩ i v := ⟨n, a.write' i v⟩
lemma read_eq_read' [inhabited α] (b : buffer α) (i : nat) (h : i < b.size) : read b ⟨i, h⟩ = read' b i :=
by cases b; unfold read read'; simp [array.read_eq_read']
lemma write_eq_write' (b : buffer α) (i : nat) (h : i < b.size) (v : α) : write b ⟨i, h⟩ v = write' b i v :=
by cases b; unfold write write'; simp [array.write_eq_write']
def to_list (b : buffer α) : list α :=
b.to_array.to_list
protected def to_string (b : buffer char) : string :=
b.to_array.to_list.as_string
def append_list {α : Type u} : buffer α → list α → buffer α
| b [] := b
| b (v::vs) := append_list (b.push_back v) vs
def append_string (b : buffer char) (s : string) : buffer char :=
b.append_list s.to_list
def append_array {α : Type u} {n : nat} (nz : n > 0) : buffer α → array α n → ∀ i : nat, i < n → buffer α
| ⟨m, b⟩ a 0 _ :=
let i : fin n := ⟨n - 1, array.lt_aux_2 nz⟩ in
⟨m+1, b.push_back (a.read i)⟩
| ⟨m, b⟩ a (j+1) h :=
let i : fin n := ⟨n - 2 - j, array.lt_aux_3 h⟩ in
append_array ⟨m+1, b.push_back (a.read i)⟩ a j (array.lt_aux_1 h)
protected def append {α : Type u} : buffer α → buffer α → buffer α
| b ⟨0, a⟩ := b
| b ⟨n+1, a⟩ := append_array (nat.zero_lt_succ _) b a n (nat.lt_succ_self _)
def iterate : Π b : buffer α, β → (fin b.size → α → β → β) → β
| ⟨_, a⟩ b f := a.iterate b f
def foreach : Π b : buffer α, (fin b.size → α → α) → buffer α
| ⟨n, a⟩ f := ⟨n, a.foreach f⟩
def map (f : α → α) : buffer α → buffer α
| ⟨n, a⟩ := ⟨n, a.map f⟩
def foldl : buffer α → β → (α → β → β) → β
| ⟨_, a⟩ b f := a.foldl b f
def rev_iterate : Π (b : buffer α), β → (fin b.size → α → β → β) → β
| ⟨_, a⟩ b f := a.rev_iterate b f
def take (b : buffer α) (n : nat) : buffer α :=
if h : n ≤ b.size then ⟨n, b.to_array.take n h⟩ else b
def take_right (b : buffer α) (n : nat) : buffer α :=
if h : n ≤ b.size then ⟨n, b.to_array.take_right n h⟩ else b
def drop (b : buffer α) (n : nat) : buffer α :=
if h : n ≤ b.size then ⟨_, b.to_array.drop n h⟩ else b
def reverse (b : buffer α) : buffer α :=
⟨b.size, b.to_array.reverse⟩
protected def mem (v : α) (a : buffer α) : Prop := ∃i, read a i = v
instance : has_mem α (buffer α) := ⟨buffer.mem⟩
instance : has_append (buffer α) :=
⟨buffer.append⟩
instance [has_repr α] : has_repr (buffer α) :=
⟨repr ∘ to_list⟩
meta instance [has_to_format α] : has_to_format (buffer α) :=
⟨to_fmt ∘ to_list⟩
meta instance [has_to_tactic_format α] : has_to_tactic_format (buffer α) :=
⟨tactic.pp ∘ to_list⟩
end buffer
def list.to_buffer {α : Type u} (l : list α) : buffer α :=
mk_buffer.append_list l
@[reducible] def char_buffer := buffer char
/-- Convert a format object into a character buffer with the provided
formatting options. -/
meta constant format.to_buffer : format → options → buffer char
def string.to_char_buffer (s : string) : char_buffer :=
buffer.nil.append_string s
|
1b00958b9f725163fec1dfda1eb36d196a025add | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/algebra/hierarchy_design.lean | b7a10e8f84d967b7f2be7693b1f1164225ce72ed | [
"Apache-2.0"
] | permissive | jjgarzella/mathlib | 96a345378c4e0bf26cf604aed84f90329e4896a2 | 395d8716c3ad03747059d482090e2bb97db612c8 | refs/heads/master | 1,686,480,124,379 | 1,625,163,323,000 | 1,625,163,323,000 | 281,190,421 | 2 | 0 | Apache-2.0 | 1,595,268,170,000 | 1,595,268,169,000 | null | UTF-8 | Lean | false | false | 9,041 | lean | /-
Copyright (c) 2021 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison, Eric Weiser
-/
import tactic.doc_commands
/-!
# Documentation of the algebraic hierarchy
A library note giving advice on modifying the algebraic hierarchy.
(It is not intended as a "tour".)
TODO: Add sections about interactions with topological typeclasses, and order typeclasses.
-/
/--
# The algebraic hierarchy
In any theorem proving environment,
there are difficult decisions surrounding the design of the "algebraic hierarchy".
There is a danger of exponential explosion in the number of gadgets,
especially once interactions between algebraic and order/topological/etc structures are considered.
In mathlib, we try to avoid this by only introducing new algebraic typeclasses either
1. when there is "real mathematics" to be done with them, or
2. when there is a meaninful gain in simplicity by factoring out a common substructure.
(As examples, at this point we don't have `loop`, or `unital_magma`,
but we do have `lie_submodule` and `topological_field`!
We also have `group_with_zero`, as an exemplar of point 2.)
Generally in mathlib we use the extension mechanism (so `comm_ring` extends `ring`)
rather than mixins (e.g. with separate `ring` and `comm_mul` classes),
in part because of the potential blow-up in term sizes described at
https://www.ralfj.de/blog/2019/05/15/typeclasses-exponential-blowup.html
However there is tension here, as it results in considerable duplication in the API,
particularly in the interaction with order structures.
This library note is not intended as a design document
justifying and explaining the history of mathlib's algebraic hierarchy!
Instead it is intended as a developer's guide, for contributors wanting to extend
(either new leaves, or new intermediate classes) the algebraic hierarchy as it exists.
(Ideally we would have both a tour guide to the existing hierarchy,
and an account of the design choices.
See https://arxiv.org/abs/1910.09336 for an overview of mathlib as a whole,
with some attention to the algebraic hierarchy and
https://leanprover-community.github.io/mathlib-overview.html
for a summary of what is in mathlib today.)
## Instances
When adding a new typeclass `Z` to the algebraic hierarchy
one should attempt to add the following constructions and results,
when applicable:
* Instances transferred elementwise to products, like `prod.monoid`.
See `algebra.group.prod` for more examples.
```
instance prod.Z [Z M] [Z N] : Z (M × N) := ...
```
* Instances transferred elementwise to pi types, like `pi.monoid`.
See `algebra.group.pi` for more examples.
```
instance pi.Z [∀ i, Z $ f i] : Z (Π i : I, f i) := ...
```
* Instances transferred to `opposite M`, like `opposite.monoid`.
See `algebra.opposites` for more examples.
```
instance opposite.Z [Z M] : Z (opposite M) := ...
```
* Instances transferred to `ulift M`, like `ulift.monoid`.
See `algebra.group.ulift` for more examples.
```
instance ulift.Z [Z M] : Z (ulift M) := ...
```
* Definitions for transferring the proof fields of instances along
injective or surjective functions that agree on the data fields,
like `function.injective.monoid` and `function.surjective.monoid`.
We make these definitions `@[reducible]`, see note [reducible non-instances].
See `algebra.group.inj_surj` for more examples.
```
@[reducible]
def function.injective.Z [Z M₂] (f : M₁ → M₂) (hf : injective f)
(one : f 1 = 1) (mul : ∀ x y, f (x * y) = f x * f y) : Z M₁ := ...
@[reducible]
def function.surjective.Z [Z M₁] (f : M₁ → M₂) (hf : surjective f)
(one : f 1 = 1) (mul : ∀ x y, f (x * y) = f x * f y) : Z M₂ := ...
```
* Instances transferred elementwise to `finsupp`s, like `finsupp.semigroup`.
See `data.finsupp.pointwise` for more examples.
```
instance finsupp.Z [Z β] : Z (α →₀ β) := ...
```
* Instances transferred elementwise to `set`s, like `set.monoid`.
See `algebra.pointwise` for more examples.
```
instance set.Z [Z α] : Z (set α) := ...
```
* Definitions for transferring the entire structure across an equivalence, like `equiv.monoid`.
See `data.equiv.transfer_instance` for more examples. See also the `transport` tactic.
```
def equiv.Z (e : α ≃ β) [Z β] : Z α := ...
/- When there is a new notion of `Z`-equiv: -/
def equiv.Z_equiv (e : α ≃ β) [Z β] : by { letI := equiv.Z e, exact α ≃Z β } := ...
```
## Subobjects
When a new typeclass `Z` adds new data fields,
you should also create a new `sub_Z` `structure` with a `carrier` field.
This can be a lot of work; for now try to closely follow the existing examples
(e.g. `submonoid`, `subring`, `subalgebra`).
We would very much like to provide some automation here, but a prerequisite will be making
all the existing APIs more uniform.
If `Z` extends `Y`, then `sub_Z` should usually extend `sub_Y`.
When `Z` adds only new proof fields to an existing structure `Y`,
you should provide instances transferring
`Z α` to `Z (sub_Y α)`, like `submonoid.to_comm_monoid`.
Typically this is done using the `function.injective.Z` definition mentioned above.
```
instance sub_Y.to_Z [Z α] : Z (sub_Y α) :=
coe_injective.Z coe ...
```
## Morphisms and equivalences
## Category theory
For many algebraic structures, particularly ones used in representation theory, algebraic geometry,
etc., we also define "bundled" versions, which carry `category` instances.
These bundled versions are usually named in camel case,
so for example we have `AddCommGroup` as a bundled `add_comm_group`,
and `TopCommRing` (which bundles together `comm_ring`, `topological_space`, and `topological_ring`).
These bundled versions have many appealing features:
* a uniform notation for morphisms `X ⟶ Y`
* a uniform notation (and definition) for isomorphisms `X ≅ Y`
* a uniform API for subobjects, via the partial order `subobject X`
* interoperability with unbundled structures, via coercions to `Type`
(so if `G : AddCommGroup`, you can treat `G` as a type,
and it automatically has an `add_comm_group` instance)
and lifting maps `AddCommGroup.of G`, when `G` is a type with an `add_comm_group` instance.
If, for example you do the work of proving that a typeclass `Z` has a good notion of tensor product,
you are strongly encouraged to provide the corresponding `monoidal_category` instance
on a bundled version.
This ensures that the API for tensor products is complete, and enables use of general machinery.
Similarly if you prove universal properties, or adjunctions, you are encouraged to state these
using categorical language!
One disadvantage of the bundled approach is that we can only speak of morphisms between
objects living in the same type-theoretic universe.
In practice this is rarely a problem.
# Making a pull request
With so many moving parts, how do you actually go about changing the algebraic hierarchy?
We're still evolving how to handle this, but the current suggestion is:
* If you're adding a new "leaf" class, the requirements are lower,
and an initial PR can just add whatever is immediately needed.
* A new "intermediate" class, especially low down in the hierarchy,
needs to be careful about leaving gaps.
In a perfect world, there would be a group of simultaneous PRs that basically cover everything!
(Or at least an expectation that PRs may not be merged immediately while waiting on other
PRs that fill out the API.)
However "perfect is the enemy of good", and it would also be completely reasonable
to add a TODO list in the main module doc-string for the new class,
briefly listing the parts of the API which still need to be provided.
Hopefully this document makes it easy to assemble this list.
Another alternative to a TODO list in the doc-strings is adding github issues.
-/
library_note "the algebraic hierarchy"
/--
Some definitions that define objects of a class cannot be instances, because they have an
explicit argument that does not occur in the conclusion. An example is `preorder.lift` that has a
function `f : α → β` as an explicit argument to lift a preorder on `β` to a preorder on `α`.
If these definitions are used to define other instances *and* it is important that these other
instances will be unfolded by type-class inference, then these definitions should be marked
`@[reducible]`.
For example, `preorder.lift` is used to define `units.preorder` and `partial_order.lift` is used
to define `units.partial_order`. In some cases it is important that type-class inference can
recognize that `units.preorder` and `units.partial_order` give rise to the same `has_le` instance.
For example, you might have another class that takes `[has_le α]` as an argument, and this argument
sometimes comes from `units.preorder` and sometimes from `units.partial_order`.
Therefore, `preorder.lift` and `partial_order.lift` are marked `@[reducible]`.
-/
library_note "reducible non-instances"
|
dbc6ba64ba6d8791f5827b936cff6dee323e42df | 4727251e0cd73359b15b664c3170e5d754078599 | /src/linear_algebra/matrix/charpoly/minpoly.lean | d65cfc36474c3f0e4fa5b6e24e510fca8f525058 | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 1,816 | lean | /-
Copyright (c) 2020 Aaron Anderson, Jalex Stark. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Aaron Anderson, Jalex Stark
-/
import linear_algebra.matrix.charpoly.coeff
import ring_theory.power_basis
/-!
# The minimal polynomial divides the characteristic polynomial of a matrix.
-/
noncomputable theory
universes u v
open polynomial matrix
variables {R : Type u} [comm_ring R]
variables {n : Type v} [decidable_eq n] [fintype n]
open finset
variable {M : matrix n n R}
namespace matrix
theorem is_integral : is_integral R M := ⟨M.charpoly, ⟨charpoly_monic M, aeval_self_charpoly M⟩⟩
theorem minpoly_dvd_charpoly {K : Type*} [field K] (M : matrix n n K) :
(minpoly K M) ∣ M.charpoly :=
minpoly.dvd _ _ (aeval_self_charpoly M)
end matrix
section power_basis
open algebra
/-- The characteristic polynomial of the map `λ x, a * x` is the minimal polynomial of `a`.
In combination with `det_eq_sign_charpoly_coeff` or `trace_eq_neg_charpoly_coeff`
and a bit of rewriting, this will allow us to conclude the
field norm resp. trace of `x` is the product resp. sum of `x`'s conjugates.
-/
lemma charpoly_left_mul_matrix {K S : Type*} [field K] [comm_ring S] [algebra K S]
(h : power_basis K S) :
(left_mul_matrix h.basis h.gen).charpoly = minpoly K h.gen :=
begin
apply minpoly.unique,
{ apply matrix.charpoly_monic },
{ apply (injective_iff_map_eq_zero (left_mul_matrix _)).mp (left_mul_matrix_injective h.basis),
rw [← polynomial.aeval_alg_hom_apply, aeval_self_charpoly] },
{ intros q q_monic root_q,
rw [matrix.charpoly_degree_eq_dim, fintype.card_fin, degree_eq_nat_degree q_monic.ne_zero],
apply with_bot.some_le_some.mpr,
exact h.dim_le_nat_degree_of_root q_monic.ne_zero root_q }
end
end power_basis
|
325ddd6de96be4bbff4f975d476c9ee86d123e4b | 4d2583807a5ac6caaffd3d7a5f646d61ca85d532 | /src/measure_theory/measure/complex.lean | 1a81e6bf31ea62003bc95c3144e0fd46f976e141 | [
"Apache-2.0"
] | permissive | AntoineChambert-Loir/mathlib | 64aabb896129885f12296a799818061bc90da1ff | 07be904260ab6e36a5769680b6012f03a4727134 | refs/heads/master | 1,693,187,631,771 | 1,636,719,886,000 | 1,636,719,886,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 4,464 | lean | /-
Copyright (c) 2021 Kexing Ying. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kexing Ying
-/
import measure_theory.decomposition.jordan
/-!
# Complex measure
This file proves some elementary results about complex measures. In particular, we prove that
a complex measure is always in the form `s + it` where `s` and `t` are signed measures.
The complex measure is defined to be vector measure over `ℂ`, this definition can be found
in `measure_theory.measure.vector_measure` and is known as `measure_theory.complex_measure`.
## Main definitions
* `measure_theory.complex_measure.re`: obtains a signed measure `s` from a complex measure `c`
such that `s i = (c i).re` for all measurable sets `i`.
* `measure_theory.complex_measure.im`: obtains a signed measure `s` from a complex measure `c`
such that `s i = (c i).im` for all measurable sets `i`.
* `measure_theory.signed_measure.to_complex_measure`: given two signed measures `s` and `t`,
`s.to_complex_measure t` provides a complex measure of the form `s + it`.
* `measure_theory.complex_measure.equiv_signed_measure`: is the equivalence between the complex
measures and the type of the product of the signed measures with itself.
# Tags
Complex measure
-/
noncomputable theory
open_locale classical measure_theory ennreal nnreal
variables {α β : Type*} {m : measurable_space α}
namespace measure_theory
open vector_measure
namespace complex_measure
include m
/-- The real part of a complex measure is a signed measure. -/
@[simps apply]
def re : complex_measure α →ₗ[ℝ] signed_measure α :=
map_rangeₗ complex.re_clm complex.continuous_re
/-- The imaginary part of a complex measure is a signed measure. -/
@[simps apply]
def im : complex_measure α →ₗ[ℝ] signed_measure α :=
map_rangeₗ complex.im_clm complex.continuous_im
/-- Given `s` and `t` signed measures, `s + it` is a complex measure-/
@[simps]
def _root_.measure_theory.signed_measure.to_complex_measure (s t : signed_measure α) :
complex_measure α :=
{ measure_of' := λ i, ⟨s i, t i⟩,
empty' := by rw [s.empty, t.empty]; refl,
not_measurable' := λ i hi, by rw [s.not_measurable hi, t.not_measurable hi]; refl,
m_Union' := λ f hf hfdisj,
(complex.has_sum_iff _ _).2 ⟨s.m_Union hf hfdisj, t.m_Union hf hfdisj⟩ }
lemma _root_.measure_theory.signed_measure.to_complex_measure_apply
{s t : signed_measure α} {i : set α} : s.to_complex_measure t i = ⟨s i, t i⟩ := rfl
lemma to_complex_measure_to_signed_measure (c : complex_measure α) :
c.re.to_complex_measure c.im = c :=
by { ext i hi; refl }
lemma _root_.measure_theory.signed_measure.re_to_complex_measure
(s t : signed_measure α) : (s.to_complex_measure t).re = s :=
by { ext i hi, refl }
lemma _root_.measure_theory.signed_measure.im_to_complex_measure
(s t : signed_measure α) : (s.to_complex_measure t).im = t :=
by { ext i hi, refl }
/-- The complex measures form an equivalence to the type of pairs of signed measures. -/
@[simps]
def equiv_signed_measure : complex_measure α ≃ signed_measure α × signed_measure α :=
{ to_fun := λ c, ⟨c.re, c.im⟩,
inv_fun := λ ⟨s, t⟩, s.to_complex_measure t,
left_inv := λ c, c.to_complex_measure_to_signed_measure,
right_inv := λ ⟨s, t⟩,
prod.mk.inj_iff.2 ⟨s.re_to_complex_measure t, s.im_to_complex_measure t⟩ }
section
variables {R : Type*} [semiring R] [module R ℝ]
variables [topological_space R] [has_continuous_smul R ℝ] [has_continuous_smul R ℂ]
/-- The complex measures form an linear isomorphism to the type of pairs of signed measures. -/
@[simps]
def equiv_signed_measureₗ : complex_measure α ≃ₗ[R] signed_measure α × signed_measure α :=
{ map_add' := λ c d, by { ext i hi; refl },
map_smul' :=
begin
intros r c, ext i hi,
{ change (r • c i).re = r • (c i).re,
simp [complex.smul_re] },
{ ext i hi,
change (r • c i).im = r • (c i).im,
simp [complex.smul_im] }
end, .. equiv_signed_measure }
end
lemma absolutely_continuous_ennreal_iff (c : complex_measure α) (μ : vector_measure α ℝ≥0∞) :
c ≪ᵥ μ ↔ c.re ≪ᵥ μ ∧ c.im ≪ᵥ μ :=
begin
split; intro h,
{ split; { intros i hi, simp [h hi] } },
{ intros i hi,
rw [← complex.re_add_im (c i), (_ : (c i).re = 0), (_ : (c i).im = 0)],
exacts [by simp, h.2 hi, h.1 hi] }
end
end complex_measure
end measure_theory
|
73cdfd1c7bd8d92910394b6040ec641c5b8f134c | 4727251e0cd73359b15b664c3170e5d754078599 | /src/topology/local_homeomorph.lean | a7a47153169bb8ee46d73cad9e2d723992bc6929 | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 47,842 | lean | /-
Copyright (c) 2019 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Sébastien Gouëzel
-/
import logic.equiv.local_equiv
import topology.sets.opens
/-!
# Local homeomorphisms
This file defines homeomorphisms between open subsets of topological spaces. An element `e` of
`local_homeomorph α β` is an extension of `local_equiv α β`, i.e., it is a pair of functions
`e.to_fun` and `e.inv_fun`, inverse of each other on the sets `e.source` and `e.target`.
Additionally, we require that these sets are open, and that the functions are continuous on them.
Equivalently, they are homeomorphisms there.
As in equivs, we register a coercion to functions, and we use `e x` and `e.symm x` throughout
instead of `e.to_fun x` and `e.inv_fun x`.
## Main definitions
`homeomorph.to_local_homeomorph`: associating a local homeomorphism to a homeomorphism, with
source = target = univ
`local_homeomorph.symm` : the inverse of a local homeomorphism
`local_homeomorph.trans` : the composition of two local homeomorphisms
`local_homeomorph.refl` : the identity local homeomorphism
`local_homeomorph.of_set`: the identity on a set `s`
`eq_on_source` : equivalence relation describing the "right" notion of equality for local
homeomorphisms
## Implementation notes
Most statements are copied from their local_equiv versions, although some care is required
especially when restricting to subsets, as these should be open subsets.
For design notes, see `local_equiv.lean`.
### Local coding conventions
If a lemma deals with the intersection of a set with either source or target of a `local_equiv`,
then it should use `e.source ∩ s` or `e.target ∩ t`, not `s ∩ e.source` or `t ∩ e.target`.
-/
open function set filter topological_space (second_countable_topology)
open_locale topological_space
variables {α : Type*} {β : Type*} {γ : Type*} {δ : Type*}
[topological_space α] [topological_space β] [topological_space γ] [topological_space δ]
/-- local homeomorphisms, defined on open subsets of the space -/
@[nolint has_inhabited_instance]
structure local_homeomorph (α : Type*) (β : Type*) [topological_space α] [topological_space β]
extends local_equiv α β :=
(open_source : is_open source)
(open_target : is_open target)
(continuous_to_fun : continuous_on to_fun source)
(continuous_inv_fun : continuous_on inv_fun target)
/-- A homeomorphism induces a local homeomorphism on the whole space -/
def homeomorph.to_local_homeomorph (e : α ≃ₜ β) :
local_homeomorph α β :=
{ open_source := is_open_univ,
open_target := is_open_univ,
continuous_to_fun := by { erw ← continuous_iff_continuous_on_univ, exact e.continuous_to_fun },
continuous_inv_fun := by { erw ← continuous_iff_continuous_on_univ, exact e.continuous_inv_fun },
..e.to_equiv.to_local_equiv }
namespace local_homeomorph
variables (e : local_homeomorph α β) (e' : local_homeomorph β γ)
instance : has_coe_to_fun (local_homeomorph α β) (λ _, α → β) := ⟨λ e, e.to_fun⟩
/-- The inverse of a local homeomorphism -/
protected def symm : local_homeomorph β α :=
{ open_source := e.open_target,
open_target := e.open_source,
continuous_to_fun := e.continuous_inv_fun,
continuous_inv_fun := e.continuous_to_fun,
..e.to_local_equiv.symm }
/-- See Note [custom simps projection]. We need to specify this projection explicitly in this case,
because it is a composition of multiple projections. -/
def simps.apply (e : local_homeomorph α β) : α → β := e
/-- See Note [custom simps projection] -/
def simps.symm_apply (e : local_homeomorph α β) : β → α := e.symm
initialize_simps_projections local_homeomorph
(to_local_equiv_to_fun → apply, to_local_equiv_inv_fun → symm_apply,
to_local_equiv_source → source, to_local_equiv_target → target, -to_local_equiv)
protected lemma continuous_on : continuous_on e e.source := e.continuous_to_fun
lemma continuous_on_symm : continuous_on e.symm e.target := e.continuous_inv_fun
@[simp, mfld_simps] lemma mk_coe (e : local_equiv α β) (a b c d) :
(local_homeomorph.mk e a b c d : α → β) = e := rfl
@[simp, mfld_simps] lemma mk_coe_symm (e : local_equiv α β) (a b c d) :
((local_homeomorph.mk e a b c d).symm : β → α) = e.symm := rfl
/- Register a few simp lemmas to make sure that `simp` puts the application of a local
homeomorphism in its normal form, i.e., in terms of its coercion to a function. -/
@[simp, mfld_simps] lemma to_fun_eq_coe (e : local_homeomorph α β) : e.to_fun = e := rfl
@[simp, mfld_simps] lemma inv_fun_eq_coe (e : local_homeomorph α β) : e.inv_fun = e.symm := rfl
@[simp, mfld_simps] lemma coe_coe : (e.to_local_equiv : α → β) = e := rfl
@[simp, mfld_simps] lemma coe_coe_symm : (e.to_local_equiv.symm : β → α) = e.symm := rfl
@[simp, mfld_simps] lemma map_source {x : α} (h : x ∈ e.source) : e x ∈ e.target :=
e.map_source' h
@[simp, mfld_simps] lemma map_target {x : β} (h : x ∈ e.target) : e.symm x ∈ e.source :=
e.map_target' h
@[simp, mfld_simps] lemma left_inv {x : α} (h : x ∈ e.source) : e.symm (e x) = x :=
e.left_inv' h
@[simp, mfld_simps] lemma right_inv {x : β} (h : x ∈ e.target) : e (e.symm x) = x :=
e.right_inv' h
protected lemma maps_to : maps_to e e.source e.target := λ x, e.map_source
protected lemma symm_maps_to : maps_to e.symm e.target e.source := e.symm.maps_to
protected lemma left_inv_on : left_inv_on e.symm e e.source := λ x, e.left_inv
protected lemma right_inv_on : right_inv_on e.symm e e.target := λ x, e.right_inv
protected lemma inv_on : inv_on e.symm e e.source e.target := ⟨e.left_inv_on, e.right_inv_on⟩
protected lemma inj_on : inj_on e e.source := e.left_inv_on.inj_on
protected lemma bij_on : bij_on e e.source e.target := e.inv_on.bij_on e.maps_to e.symm_maps_to
protected lemma surj_on : surj_on e e.source e.target := e.bij_on.surj_on
/-- Replace `to_local_equiv` field to provide better definitional equalities. -/
def replace_equiv (e : local_homeomorph α β) (e' : local_equiv α β) (h : e.to_local_equiv = e') :
local_homeomorph α β :=
{ to_local_equiv := e',
open_source := h ▸ e.open_source,
open_target := h ▸ e.open_target,
continuous_to_fun := h ▸ e.continuous_to_fun,
continuous_inv_fun := h ▸ e.continuous_inv_fun }
lemma replace_equiv_eq_self (e : local_homeomorph α β) (e' : local_equiv α β)
(h : e.to_local_equiv = e') :
e.replace_equiv e' h = e :=
by { cases e, subst e', refl }
lemma source_preimage_target : e.source ⊆ e ⁻¹' e.target := e.maps_to
lemma eq_of_local_equiv_eq {e e' : local_homeomorph α β}
(h : e.to_local_equiv = e'.to_local_equiv) : e = e' :=
by { cases e, cases e', cases h, refl }
lemma eventually_left_inverse (e : local_homeomorph α β) {x} (hx : x ∈ e.source) :
∀ᶠ y in 𝓝 x, e.symm (e y) = y :=
(e.open_source.eventually_mem hx).mono e.left_inv'
lemma eventually_left_inverse' (e : local_homeomorph α β) {x} (hx : x ∈ e.target) :
∀ᶠ y in 𝓝 (e.symm x), e.symm (e y) = y :=
e.eventually_left_inverse (e.map_target hx)
lemma eventually_right_inverse (e : local_homeomorph α β) {x} (hx : x ∈ e.target) :
∀ᶠ y in 𝓝 x, e (e.symm y) = y :=
(e.open_target.eventually_mem hx).mono e.right_inv'
lemma eventually_right_inverse' (e : local_homeomorph α β) {x} (hx : x ∈ e.source) :
∀ᶠ y in 𝓝 (e x), e (e.symm y) = y :=
e.eventually_right_inverse (e.map_source hx)
lemma eventually_ne_nhds_within (e : local_homeomorph α β) {x} (hx : x ∈ e.source) :
∀ᶠ x' in 𝓝[≠] x, e x' ≠ e x :=
eventually_nhds_within_iff.2 $ (e.eventually_left_inverse hx).mono $
λ x' hx', mt $ λ h, by rw [mem_singleton_iff, ← e.left_inv hx, ← h, hx']
lemma nhds_within_source_inter {x} (hx : x ∈ e.source) (s : set α) :
𝓝[e.source ∩ s] x = 𝓝[s] x :=
nhds_within_inter_of_mem (mem_nhds_within_of_mem_nhds $ is_open.mem_nhds e.open_source hx)
lemma nhds_within_target_inter {x} (hx : x ∈ e.target) (s : set β) :
𝓝[e.target ∩ s] x = 𝓝[s] x :=
e.symm.nhds_within_source_inter hx s
lemma image_eq_target_inter_inv_preimage {s : set α} (h : s ⊆ e.source) :
e '' s = e.target ∩ e.symm ⁻¹' s :=
e.to_local_equiv.image_eq_target_inter_inv_preimage h
lemma image_source_inter_eq' (s : set α) :
e '' (e.source ∩ s) = e.target ∩ e.symm ⁻¹' s :=
e.to_local_equiv.image_source_inter_eq' s
lemma image_source_inter_eq (s : set α) :
e '' (e.source ∩ s) = e.target ∩ e.symm ⁻¹' (e.source ∩ s) :=
e.to_local_equiv.image_source_inter_eq s
lemma symm_image_eq_source_inter_preimage {s : set β} (h : s ⊆ e.target) :
e.symm '' s = e.source ∩ e ⁻¹' s :=
e.symm.image_eq_target_inter_inv_preimage h
lemma symm_image_target_inter_eq (s : set β) :
e.symm '' (e.target ∩ s) = e.source ∩ e ⁻¹' (e.target ∩ s) :=
e.symm.image_source_inter_eq _
lemma source_inter_preimage_inv_preimage (s : set α) :
e.source ∩ e ⁻¹' (e.symm ⁻¹' s) = e.source ∩ s :=
e.to_local_equiv.source_inter_preimage_inv_preimage s
lemma target_inter_inv_preimage_preimage (s : set β) :
e.target ∩ e.symm ⁻¹' (e ⁻¹' s) = e.target ∩ s :=
e.symm.source_inter_preimage_inv_preimage _
lemma source_inter_preimage_target_inter (s : set β) :
e.source ∩ (e ⁻¹' (e.target ∩ s)) = e.source ∩ (e ⁻¹' s) :=
e.to_local_equiv.source_inter_preimage_target_inter s
/-- Two local homeomorphisms are equal when they have equal `to_fun`, `inv_fun` and `source`.
It is not sufficient to have equal `to_fun` and `source`, as this only determines `inv_fun` on
the target. This would only be true for a weaker notion of equality, arguably the right one,
called `eq_on_source`. -/
@[ext]
protected lemma ext (e' : local_homeomorph α β) (h : ∀x, e x = e' x)
(hinv : ∀x, e.symm x = e'.symm x) (hs : e.source = e'.source) : e = e' :=
eq_of_local_equiv_eq (local_equiv.ext h hinv hs)
@[simp, mfld_simps] lemma symm_to_local_equiv : e.symm.to_local_equiv = e.to_local_equiv.symm := rfl
-- The following lemmas are already simp via local_equiv
lemma symm_source : e.symm.source = e.target := rfl
lemma symm_target : e.symm.target = e.source := rfl
@[simp, mfld_simps] lemma symm_symm : e.symm.symm = e := eq_of_local_equiv_eq $ by simp
/-- A local homeomorphism is continuous at any point of its source -/
protected lemma continuous_at {x : α} (h : x ∈ e.source) : continuous_at e x :=
(e.continuous_on x h).continuous_at (is_open.mem_nhds e.open_source h)
/-- A local homeomorphism inverse is continuous at any point of its target -/
lemma continuous_at_symm {x : β} (h : x ∈ e.target) : continuous_at e.symm x :=
e.symm.continuous_at h
lemma tendsto_symm {x} (hx : x ∈ e.source) :
tendsto e.symm (𝓝 (e x)) (𝓝 x) :=
by simpa only [continuous_at, e.left_inv hx] using e.continuous_at_symm (e.map_source hx)
lemma map_nhds_eq {x} (hx : x ∈ e.source) : map e (𝓝 x) = 𝓝 (e x) :=
le_antisymm (e.continuous_at hx) $
le_map_of_right_inverse (e.eventually_right_inverse' hx) (e.tendsto_symm hx)
lemma symm_map_nhds_eq {x} (hx : x ∈ e.source) :
map e.symm (𝓝 (e x)) = 𝓝 x :=
(e.symm.map_nhds_eq $ e.map_source hx).trans $ by rw e.left_inv hx
lemma image_mem_nhds {x} (hx : x ∈ e.source) {s : set α} (hs : s ∈ 𝓝 x) :
e '' s ∈ 𝓝 (e x) :=
e.map_nhds_eq hx ▸ filter.image_mem_map hs
lemma map_nhds_within_eq (e : local_homeomorph α β) {x} (hx : x ∈ e.source) (s : set α) :
map e (𝓝[s] x) = 𝓝[e '' (e.source ∩ s)] (e x) :=
calc map e (𝓝[s] x) = map e (𝓝[e.source ∩ s] x) :
congr_arg (map e) (e.nhds_within_source_inter hx _).symm
... = 𝓝[e '' (e.source ∩ s)] (e x) :
(e.left_inv_on.mono $ inter_subset_left _ _).map_nhds_within_eq (e.left_inv hx)
(e.continuous_at_symm (e.map_source hx)).continuous_within_at
(e.continuous_at hx).continuous_within_at
lemma map_nhds_within_preimage_eq (e : local_homeomorph α β) {x} (hx : x ∈ e.source) (s : set β) :
map e (𝓝[e ⁻¹' s] x) = 𝓝[s] (e x) :=
by rw [e.map_nhds_within_eq hx, e.image_source_inter_eq', e.target_inter_inv_preimage_preimage,
e.nhds_within_target_inter (e.map_source hx)]
lemma preimage_open_of_open {s : set β} (hs : is_open s) : is_open (e.source ∩ e ⁻¹' s) :=
e.continuous_on.preimage_open_of_open e.open_source hs
/-!
### `local_homeomorph.is_image` relation
We say that `t : set β` is an image of `s : set α` under a local homeomorphism `e` if any of the
following equivalent conditions hold:
* `e '' (e.source ∩ s) = e.target ∩ t`;
* `e.source ∩ e ⁻¹ t = e.source ∩ s`;
* `∀ x ∈ e.source, e x ∈ t ↔ x ∈ s` (this one is used in the definition).
This definition is a restatement of `local_equiv.is_image` for local homeomorphisms. In this section
we transfer API about `local_equiv.is_image` to local homeomorphisms and add a few
`local_homeomorph`-specific lemmas like `local_homeomorph.is_image.closure`.
-/
/-- We say that `t : set β` is an image of `s : set α` under a local homeomorphism `e` if any of the
following equivalent conditions hold:
* `e '' (e.source ∩ s) = e.target ∩ t`;
* `e.source ∩ e ⁻¹ t = e.source ∩ s`;
* `∀ x ∈ e.source, e x ∈ t ↔ x ∈ s` (this one is used in the definition).
-/
def is_image (s : set α) (t : set β) : Prop := ∀ ⦃x⦄, x ∈ e.source → (e x ∈ t ↔ x ∈ s)
namespace is_image
variables {e} {s : set α} {t : set β} {x : α} {y : β}
lemma to_local_equiv (h : e.is_image s t) : e.to_local_equiv.is_image s t := h
lemma apply_mem_iff (h : e.is_image s t) (hx : x ∈ e.source) : e x ∈ t ↔ x ∈ s := h hx
protected lemma symm (h : e.is_image s t) : e.symm.is_image t s := h.to_local_equiv.symm
lemma symm_apply_mem_iff (h : e.is_image s t) (hy : y ∈ e.target) : (e.symm y ∈ s ↔ y ∈ t) :=
h.symm hy
@[simp] lemma symm_iff : e.symm.is_image t s ↔ e.is_image s t := ⟨λ h, h.symm, λ h, h.symm⟩
protected lemma maps_to (h : e.is_image s t) : maps_to e (e.source ∩ s) (e.target ∩ t) :=
h.to_local_equiv.maps_to
lemma symm_maps_to (h : e.is_image s t) : maps_to e.symm (e.target ∩ t) (e.source ∩ s) :=
h.symm.maps_to
lemma image_eq (h : e.is_image s t) : e '' (e.source ∩ s) = e.target ∩ t :=
h.to_local_equiv.image_eq
lemma symm_image_eq (h : e.is_image s t) : e.symm '' (e.target ∩ t) = e.source ∩ s :=
h.symm.image_eq
lemma iff_preimage_eq : e.is_image s t ↔ e.source ∩ e ⁻¹' t = e.source ∩ s :=
local_equiv.is_image.iff_preimage_eq
alias iff_preimage_eq ↔ local_homeomorph.is_image.preimage_eq
local_homeomorph.is_image.of_preimage_eq
lemma iff_symm_preimage_eq : e.is_image s t ↔ e.target ∩ e.symm ⁻¹' s = e.target ∩ t :=
symm_iff.symm.trans iff_preimage_eq
alias iff_symm_preimage_eq ↔ local_homeomorph.is_image.symm_preimage_eq
local_homeomorph.is_image.of_symm_preimage_eq
lemma iff_symm_preimage_eq' :
e.is_image s t ↔ e.target ∩ e.symm ⁻¹' (e.source ∩ s) = e.target ∩ t :=
by rw [iff_symm_preimage_eq, ← image_source_inter_eq, ← image_source_inter_eq']
alias iff_symm_preimage_eq' ↔ local_homeomorph.is_image.symm_preimage_eq'
local_homeomorph.is_image.of_symm_preimage_eq'
lemma iff_preimage_eq' : e.is_image s t ↔ e.source ∩ e ⁻¹' (e.target ∩ t) = e.source ∩ s :=
symm_iff.symm.trans iff_symm_preimage_eq'
alias iff_preimage_eq' ↔ local_homeomorph.is_image.preimage_eq'
local_homeomorph.is_image.of_preimage_eq'
lemma of_image_eq (h : e '' (e.source ∩ s) = e.target ∩ t) : e.is_image s t :=
local_equiv.is_image.of_image_eq h
lemma of_symm_image_eq (h : e.symm '' (e.target ∩ t) = e.source ∩ s) : e.is_image s t :=
local_equiv.is_image.of_symm_image_eq h
protected lemma compl (h : e.is_image s t) : e.is_image sᶜ tᶜ :=
λ x hx, not_congr (h hx)
protected lemma inter {s' t'} (h : e.is_image s t) (h' : e.is_image s' t') :
e.is_image (s ∩ s') (t ∩ t') :=
λ x hx, and_congr (h hx) (h' hx)
protected lemma union {s' t'} (h : e.is_image s t) (h' : e.is_image s' t') :
e.is_image (s ∪ s') (t ∪ t') :=
λ x hx, or_congr (h hx) (h' hx)
protected lemma diff {s' t'} (h : e.is_image s t) (h' : e.is_image s' t') :
e.is_image (s \ s') (t \ t') :=
h.inter h'.compl
lemma left_inv_on_piecewise {e' : local_homeomorph α β} [∀ i, decidable (i ∈ s)]
[∀ i, decidable (i ∈ t)] (h : e.is_image s t) (h' : e'.is_image s t) :
left_inv_on (t.piecewise e.symm e'.symm) (s.piecewise e e') (s.ite e.source e'.source) :=
h.to_local_equiv.left_inv_on_piecewise h'
lemma inter_eq_of_inter_eq_of_eq_on {e' : local_homeomorph α β} (h : e.is_image s t)
(h' : e'.is_image s t) (hs : e.source ∩ s = e'.source ∩ s) (Heq : eq_on e e' (e.source ∩ s)) :
e.target ∩ t = e'.target ∩ t :=
h.to_local_equiv.inter_eq_of_inter_eq_of_eq_on h' hs Heq
lemma symm_eq_on_of_inter_eq_of_eq_on {e' : local_homeomorph α β} (h : e.is_image s t)
(hs : e.source ∩ s = e'.source ∩ s) (Heq : eq_on e e' (e.source ∩ s)) :
eq_on e.symm e'.symm (e.target ∩ t) :=
h.to_local_equiv.symm_eq_on_of_inter_eq_of_eq_on hs Heq
lemma map_nhds_within_eq (h : e.is_image s t) (hx : x ∈ e.source) :
map e (𝓝[s] x) = 𝓝[t] (e x) :=
by rw [e.map_nhds_within_eq hx, h.image_eq, e.nhds_within_target_inter (e.map_source hx)]
protected lemma closure (h : e.is_image s t) : e.is_image (closure s) (closure t) :=
λ x hx, by simp only [mem_closure_iff_nhds_within_ne_bot, ← h.map_nhds_within_eq hx, map_ne_bot_iff]
protected lemma interior (h : e.is_image s t) : e.is_image (interior s) (interior t) :=
by simpa only [closure_compl, compl_compl] using h.compl.closure.compl
protected lemma frontier (h : e.is_image s t) :
e.is_image (frontier s) (frontier t) :=
h.closure.diff h.interior
lemma is_open_iff (h : e.is_image s t) :
is_open (e.source ∩ s) ↔ is_open (e.target ∩ t) :=
⟨λ hs, h.symm_preimage_eq' ▸ e.symm.preimage_open_of_open hs,
λ hs, h.preimage_eq' ▸ e.preimage_open_of_open hs⟩
/-- Restrict a `local_homeomorph` to a pair of corresponding open sets. -/
@[simps to_local_equiv] def restr (h : e.is_image s t) (hs : is_open (e.source ∩ s)) :
local_homeomorph α β :=
{ to_local_equiv := h.to_local_equiv.restr,
open_source := hs,
open_target := h.is_open_iff.1 hs,
continuous_to_fun := e.continuous_on.mono (inter_subset_left _ _),
continuous_inv_fun := e.symm.continuous_on.mono (inter_subset_left _ _) }
end is_image
lemma is_image_source_target : e.is_image e.source e.target :=
e.to_local_equiv.is_image_source_target
lemma is_image_source_target_of_disjoint (e' : local_homeomorph α β)
(hs : disjoint e.source e'.source) (ht : disjoint e.target e'.target) :
e.is_image e'.source e'.target :=
e.to_local_equiv.is_image_source_target_of_disjoint e'.to_local_equiv hs ht
/-- Preimage of interior or interior of preimage coincide for local homeomorphisms, when restricted
to the source. -/
lemma preimage_interior (s : set β) :
e.source ∩ e ⁻¹' (interior s) = e.source ∩ interior (e ⁻¹' s) :=
(is_image.of_preimage_eq rfl).interior.preimage_eq
lemma preimage_closure (s : set β) :
e.source ∩ e ⁻¹' (closure s) = e.source ∩ closure (e ⁻¹' s) :=
(is_image.of_preimage_eq rfl).closure.preimage_eq
lemma preimage_frontier (s : set β) :
e.source ∩ e ⁻¹' (frontier s) = e.source ∩ frontier (e ⁻¹' s) :=
(is_image.of_preimage_eq rfl).frontier.preimage_eq
lemma preimage_open_of_open_symm {s : set α} (hs : is_open s) :
is_open (e.target ∩ e.symm ⁻¹' s) :=
e.symm.continuous_on.preimage_open_of_open e.open_target hs
/-- The image of an open set in the source is open. -/
lemma image_open_of_open {s : set α} (hs : is_open s) (h : s ⊆ e.source) : is_open (e '' s) :=
begin
have : e '' s = e.target ∩ e.symm ⁻¹' s :=
e.to_local_equiv.image_eq_target_inter_inv_preimage h,
rw this,
exact e.continuous_on_symm.preimage_open_of_open e.open_target hs
end
/-- The image of the restriction of an open set to the source is open. -/
lemma image_open_of_open' {s : set α} (hs : is_open s) : is_open (e '' (e.source ∩ s)) :=
image_open_of_open _ (is_open.inter e.open_source hs) (inter_subset_left _ _)
/-- A `local_equiv` with continuous open forward map and an open source is a `local_homeomorph`. -/
def of_continuous_open_restrict (e : local_equiv α β) (hc : continuous_on e e.source)
(ho : is_open_map (e.source.restrict e)) (hs : is_open e.source) :
local_homeomorph α β :=
{ to_local_equiv := e,
open_source := hs,
open_target := by simpa only [range_restrict, e.image_source_eq_target] using ho.is_open_range,
continuous_to_fun := hc,
continuous_inv_fun := e.image_source_eq_target ▸
ho.continuous_on_image_of_left_inv_on e.left_inv_on }
/-- A `local_equiv` with continuous open forward map and an open source is a `local_homeomorph`. -/
def of_continuous_open (e : local_equiv α β) (hc : continuous_on e e.source)
(ho : is_open_map e) (hs : is_open e.source) :
local_homeomorph α β :=
of_continuous_open_restrict e hc (ho.restrict hs) hs
/-- Restricting a local homeomorphism `e` to `e.source ∩ s` when `s` is open. This is sometimes hard
to use because of the openness assumption, but it has the advantage that when it can
be used then its local_equiv is defeq to local_equiv.restr -/
protected def restr_open (s : set α) (hs : is_open s) :
local_homeomorph α β :=
(@is_image.of_symm_preimage_eq α β _ _ e s (e.symm ⁻¹' s) rfl).restr
(is_open.inter e.open_source hs)
@[simp, mfld_simps] lemma restr_open_to_local_equiv (s : set α) (hs : is_open s) :
(e.restr_open s hs).to_local_equiv = e.to_local_equiv.restr s := rfl
-- Already simp via local_equiv
lemma restr_open_source (s : set α) (hs : is_open s) :
(e.restr_open s hs).source = e.source ∩ s := rfl
/-- Restricting a local homeomorphism `e` to `e.source ∩ interior s`. We use the interior to make
sure that the restriction is well defined whatever the set s, since local homeomorphisms are by
definition defined on open sets. In applications where `s` is open, this coincides with the
restriction of local equivalences -/
@[simps apply symm_apply (mfld_cfg), simps source target {attrs := []}]
protected def restr (s : set α) : local_homeomorph α β :=
e.restr_open (interior s) is_open_interior
@[simp, mfld_simps] lemma restr_to_local_equiv (s : set α) :
(e.restr s).to_local_equiv = (e.to_local_equiv).restr (interior s) := rfl
lemma restr_source' (s : set α) (hs : is_open s) : (e.restr s).source = e.source ∩ s :=
by rw [e.restr_source, hs.interior_eq]
lemma restr_to_local_equiv' (s : set α) (hs : is_open s):
(e.restr s).to_local_equiv = e.to_local_equiv.restr s :=
by rw [e.restr_to_local_equiv, hs.interior_eq]
lemma restr_eq_of_source_subset {e : local_homeomorph α β} {s : set α} (h : e.source ⊆ s) :
e.restr s = e :=
begin
apply eq_of_local_equiv_eq,
rw restr_to_local_equiv,
apply local_equiv.restr_eq_of_source_subset,
exact interior_maximal h e.open_source
end
@[simp, mfld_simps] lemma restr_univ {e : local_homeomorph α β} : e.restr univ = e :=
restr_eq_of_source_subset (subset_univ _)
lemma restr_source_inter (s : set α) : e.restr (e.source ∩ s) = e.restr s :=
begin
refine local_homeomorph.ext _ _ (λx, rfl) (λx, rfl) _,
simp [e.open_source.interior_eq, ← inter_assoc]
end
/-- The identity on the whole space as a local homeomorphism. -/
@[simps apply (mfld_cfg), simps source target {attrs := []}]
protected def refl (α : Type*) [topological_space α] : local_homeomorph α α :=
(homeomorph.refl α).to_local_homeomorph
@[simp, mfld_simps] lemma refl_local_equiv :
(local_homeomorph.refl α).to_local_equiv = local_equiv.refl α := rfl
@[simp, mfld_simps] lemma refl_symm : (local_homeomorph.refl α).symm = local_homeomorph.refl α :=
rfl
section
variables {s : set α} (hs : is_open s)
/-- The identity local equiv on a set `s` -/
@[simps apply (mfld_cfg), simps source target {attrs := []}]
def of_set (s : set α) (hs : is_open s) : local_homeomorph α α :=
{ open_source := hs,
open_target := hs,
continuous_to_fun := continuous_id.continuous_on,
continuous_inv_fun := continuous_id.continuous_on,
..local_equiv.of_set s }
@[simp, mfld_simps] lemma of_set_to_local_equiv :
(of_set s hs).to_local_equiv = local_equiv.of_set s := rfl
@[simp, mfld_simps] lemma of_set_symm : (of_set s hs).symm = of_set s hs := rfl
@[simp, mfld_simps] lemma of_set_univ_eq_refl :
of_set univ is_open_univ = local_homeomorph.refl α :=
by ext; simp
end
/-- Composition of two local homeomorphisms when the target of the first and the source of
the second coincide. -/
protected def trans' (h : e.target = e'.source) : local_homeomorph α γ :=
{ open_source := e.open_source,
open_target := e'.open_target,
continuous_to_fun := begin
apply continuous_on.comp e'.continuous_to_fun e.continuous_to_fun,
rw ← h,
exact e.to_local_equiv.source_subset_preimage_target
end,
continuous_inv_fun := begin
apply continuous_on.comp e.continuous_inv_fun e'.continuous_inv_fun,
rw h,
exact e'.to_local_equiv.target_subset_preimage_source
end,
..local_equiv.trans' e.to_local_equiv e'.to_local_equiv h }
/-- Composing two local homeomorphisms, by restricting to the maximal domain where their
composition is well defined. -/
protected def trans : local_homeomorph α γ :=
local_homeomorph.trans' (e.symm.restr_open e'.source e'.open_source).symm
(e'.restr_open e.target e.open_target) (by simp [inter_comm])
@[simp, mfld_simps] lemma trans_to_local_equiv :
(e.trans e').to_local_equiv = e.to_local_equiv.trans e'.to_local_equiv := rfl
@[simp, mfld_simps] lemma coe_trans : (e.trans e' : α → γ) = e' ∘ e := rfl
@[simp, mfld_simps] lemma coe_trans_symm : ((e.trans e').symm : γ → α) = e.symm ∘ e'.symm := rfl
lemma trans_symm_eq_symm_trans_symm : (e.trans e').symm = e'.symm.trans e.symm :=
by cases e; cases e'; refl
/- This could be considered as a simp lemma, but there are many situations where it makes something
simple into something more complicated. -/
lemma trans_source : (e.trans e').source = e.source ∩ e ⁻¹' e'.source :=
local_equiv.trans_source e.to_local_equiv e'.to_local_equiv
lemma trans_source' : (e.trans e').source = e.source ∩ e ⁻¹' (e.target ∩ e'.source) :=
local_equiv.trans_source' e.to_local_equiv e'.to_local_equiv
lemma trans_source'' : (e.trans e').source = e.symm '' (e.target ∩ e'.source) :=
local_equiv.trans_source'' e.to_local_equiv e'.to_local_equiv
lemma image_trans_source : e '' (e.trans e').source = e.target ∩ e'.source :=
local_equiv.image_trans_source e.to_local_equiv e'.to_local_equiv
lemma trans_target : (e.trans e').target = e'.target ∩ e'.symm ⁻¹' e.target := rfl
lemma trans_target' : (e.trans e').target = e'.target ∩ e'.symm ⁻¹' (e'.source ∩ e.target) :=
trans_source' e'.symm e.symm
lemma trans_target'' : (e.trans e').target = e' '' (e'.source ∩ e.target) :=
trans_source'' e'.symm e.symm
lemma inv_image_trans_target : e'.symm '' (e.trans e').target = e'.source ∩ e.target :=
image_trans_source e'.symm e.symm
lemma trans_assoc (e'' : local_homeomorph γ δ) :
(e.trans e').trans e'' = e.trans (e'.trans e'') :=
eq_of_local_equiv_eq $ local_equiv.trans_assoc e.to_local_equiv e'.to_local_equiv e''.to_local_equiv
@[simp, mfld_simps] lemma trans_refl : e.trans (local_homeomorph.refl β) = e :=
eq_of_local_equiv_eq $ local_equiv.trans_refl e.to_local_equiv
@[simp, mfld_simps] lemma refl_trans : (local_homeomorph.refl α).trans e = e :=
eq_of_local_equiv_eq $ local_equiv.refl_trans e.to_local_equiv
lemma trans_of_set {s : set β} (hs : is_open s) :
e.trans (of_set s hs) = e.restr (e ⁻¹' s) :=
local_homeomorph.ext _ _ (λx, rfl) (λx, rfl) $
by simp [local_equiv.trans_source, (e.preimage_interior _).symm, hs.interior_eq]
lemma trans_of_set' {s : set β} (hs : is_open s) :
e.trans (of_set s hs) = e.restr (e.source ∩ e ⁻¹' s) :=
by rw [trans_of_set, restr_source_inter]
lemma of_set_trans {s : set α} (hs : is_open s) :
(of_set s hs).trans e = e.restr s :=
local_homeomorph.ext _ _ (λx, rfl) (λx, rfl) $
by simp [local_equiv.trans_source, hs.interior_eq, inter_comm]
lemma of_set_trans' {s : set α} (hs : is_open s) :
(of_set s hs).trans e = e.restr (e.source ∩ s) :=
by rw [of_set_trans, restr_source_inter]
@[simp, mfld_simps] lemma of_set_trans_of_set
{s : set α} (hs : is_open s) {s' : set α} (hs' : is_open s') :
(of_set s hs).trans (of_set s' hs') = of_set (s ∩ s') (is_open.inter hs hs') :=
begin
rw (of_set s hs).trans_of_set hs',
ext; simp [hs'.interior_eq]
end
lemma restr_trans (s : set α) :
(e.restr s).trans e' = (e.trans e').restr s :=
eq_of_local_equiv_eq $ local_equiv.restr_trans e.to_local_equiv e'.to_local_equiv (interior s)
/-- `eq_on_source e e'` means that `e` and `e'` have the same source, and coincide there. They
should really be considered the same local equiv. -/
def eq_on_source (e e' : local_homeomorph α β) : Prop :=
e.source = e'.source ∧ (eq_on e e' e.source)
lemma eq_on_source_iff (e e' : local_homeomorph α β) :
eq_on_source e e' ↔ local_equiv.eq_on_source e.to_local_equiv e'.to_local_equiv :=
iff.rfl
/-- `eq_on_source` is an equivalence relation -/
instance : setoid (local_homeomorph α β) :=
{ r := eq_on_source,
iseqv := ⟨
λe, (@local_equiv.eq_on_source_setoid α β).iseqv.1 e.to_local_equiv,
λe e' h, (@local_equiv.eq_on_source_setoid α β).iseqv.2.1 ((eq_on_source_iff e e').1 h),
λe e' e'' h h', (@local_equiv.eq_on_source_setoid α β).iseqv.2.2
((eq_on_source_iff e e').1 h) ((eq_on_source_iff e' e'').1 h')⟩ }
lemma eq_on_source_refl : e ≈ e := setoid.refl _
/-- If two local homeomorphisms are equivalent, so are their inverses -/
lemma eq_on_source.symm' {e e' : local_homeomorph α β} (h : e ≈ e') : e.symm ≈ e'.symm :=
local_equiv.eq_on_source.symm' h
/-- Two equivalent local homeomorphisms have the same source -/
lemma eq_on_source.source_eq {e e' : local_homeomorph α β} (h : e ≈ e') : e.source = e'.source :=
h.1
/-- Two equivalent local homeomorphisms have the same target -/
lemma eq_on_source.target_eq {e e' : local_homeomorph α β} (h : e ≈ e') : e.target = e'.target :=
h.symm'.1
/-- Two equivalent local homeomorphisms have coinciding `to_fun` on the source -/
lemma eq_on_source.eq_on {e e' : local_homeomorph α β} (h : e ≈ e') :
eq_on e e' e.source :=
h.2
/-- Two equivalent local homeomorphisms have coinciding `inv_fun` on the target -/
lemma eq_on_source.symm_eq_on_target {e e' : local_homeomorph α β} (h : e ≈ e') :
eq_on e.symm e'.symm e.target :=
h.symm'.2
/-- Composition of local homeomorphisms respects equivalence -/
lemma eq_on_source.trans' {e e' : local_homeomorph α β} {f f' : local_homeomorph β γ}
(he : e ≈ e') (hf : f ≈ f') : e.trans f ≈ e'.trans f' :=
local_equiv.eq_on_source.trans' he hf
/-- Restriction of local homeomorphisms respects equivalence -/
lemma eq_on_source.restr {e e' : local_homeomorph α β} (he : e ≈ e') (s : set α) :
e.restr s ≈ e'.restr s :=
local_equiv.eq_on_source.restr he _
/-- Composition of a local homeomorphism and its inverse is equivalent to the restriction of the
identity to the source -/
lemma trans_self_symm :
e.trans e.symm ≈ local_homeomorph.of_set e.source e.open_source :=
local_equiv.trans_self_symm _
lemma trans_symm_self :
e.symm.trans e ≈ local_homeomorph.of_set e.target e.open_target :=
e.symm.trans_self_symm
lemma eq_of_eq_on_source_univ {e e' : local_homeomorph α β} (h : e ≈ e')
(s : e.source = univ) (t : e.target = univ) : e = e' :=
eq_of_local_equiv_eq $ local_equiv.eq_of_eq_on_source_univ _ _ h s t
section prod
/-- The product of two local homeomorphisms, as a local homeomorphism on the product space. -/
@[simps to_local_equiv apply (mfld_cfg), simps source target symm_apply {attrs := []}]
def prod (e : local_homeomorph α β) (e' : local_homeomorph γ δ) :
local_homeomorph (α × γ) (β × δ) :=
{ open_source := e.open_source.prod e'.open_source,
open_target := e.open_target.prod e'.open_target,
continuous_to_fun := e.continuous_on.prod_map e'.continuous_on,
continuous_inv_fun := e.continuous_on_symm.prod_map e'.continuous_on_symm,
to_local_equiv := e.to_local_equiv.prod e'.to_local_equiv }
@[simp, mfld_simps] lemma prod_symm (e : local_homeomorph α β) (e' : local_homeomorph γ δ) :
(e.prod e').symm = (e.symm.prod e'.symm) :=
rfl
@[simp, mfld_simps] lemma prod_trans
{η : Type*} {ε : Type*} [topological_space η] [topological_space ε]
(e : local_homeomorph α β) (f : local_homeomorph β γ)
(e' : local_homeomorph δ η) (f' : local_homeomorph η ε) :
(e.prod e').trans (f.prod f') = (e.trans f).prod (e'.trans f') :=
local_homeomorph.eq_of_local_equiv_eq $
by dsimp only [trans_to_local_equiv, prod_to_local_equiv]; apply local_equiv.prod_trans
end prod
section piecewise
/-- Combine two `local_homeomorph`s using `set.piecewise`. The source of the new `local_homeomorph`
is `s.ite e.source e'.source = e.source ∩ s ∪ e'.source \ s`, and similarly for target. The
function sends `e.source ∩ s` to `e.target ∩ t` using `e` and `e'.source \ s` to `e'.target \ t`
using `e'`, and similarly for the inverse function. To ensure that the maps `to_fun` and `inv_fun`
are inverse of each other on the new `source` and `target`, the definition assumes that the sets `s`
and `t` are related both by `e.is_image` and `e'.is_image`. To ensure that the new maps are
continuous on `source`/`target`, it also assumes that `e.source` and `e'.source` meet `frontier s`
on the same set and `e x = e' x` on this intersection. -/
@[simps to_local_equiv apply {fully_applied := ff}]
def piecewise (e e' : local_homeomorph α β) (s : set α) (t : set β)
[∀ x, decidable (x ∈ s)] [∀ y, decidable (y ∈ t)] (H : e.is_image s t) (H' : e'.is_image s t)
(Hs : e.source ∩ frontier s = e'.source ∩ frontier s)
(Heq : eq_on e e' (e.source ∩ frontier s)) :
local_homeomorph α β :=
{ to_local_equiv := e.to_local_equiv.piecewise e'.to_local_equiv s t H H',
open_source := e.open_source.ite e'.open_source Hs,
open_target := e.open_target.ite e'.open_target $
H.frontier.inter_eq_of_inter_eq_of_eq_on H'.frontier Hs Heq,
continuous_to_fun := continuous_on_piecewise_ite e.continuous_on e'.continuous_on Hs Heq,
continuous_inv_fun := continuous_on_piecewise_ite e.continuous_on_symm e'.continuous_on_symm
(H.frontier.inter_eq_of_inter_eq_of_eq_on H'.frontier Hs Heq)
(H.frontier.symm_eq_on_of_inter_eq_of_eq_on Hs Heq) }
@[simp] lemma symm_piecewise (e e' : local_homeomorph α β) {s : set α} {t : set β}
[∀ x, decidable (x ∈ s)] [∀ y, decidable (y ∈ t)] (H : e.is_image s t) (H' : e'.is_image s t)
(Hs : e.source ∩ frontier s = e'.source ∩ frontier s)
(Heq : eq_on e e' (e.source ∩ frontier s)) :
(e.piecewise e' s t H H' Hs Heq).symm =
e.symm.piecewise e'.symm t s H.symm H'.symm
(H.frontier.inter_eq_of_inter_eq_of_eq_on H'.frontier Hs Heq)
(H.frontier.symm_eq_on_of_inter_eq_of_eq_on Hs Heq) :=
rfl
/-- Combine two `local_homeomorph`s with disjoint sources and disjoint targets. We reuse
`local_homeomorph.piecewise` then override `to_local_equiv` to `local_equiv.disjoint_union`.
This way we have better definitional equalities for `source` and `target`. -/
def disjoint_union (e e' : local_homeomorph α β)
[∀ x, decidable (x ∈ e.source)] [∀ y, decidable (y ∈ e.target)]
(Hs : disjoint e.source e'.source) (Ht : disjoint e.target e'.target) :
local_homeomorph α β :=
(e.piecewise e' e.source e.target e.is_image_source_target
(e'.is_image_source_target_of_disjoint e Hs.symm Ht.symm)
(by rw [e.open_source.inter_frontier_eq, e'.open_source.inter_frontier_eq_empty_of_disjoint Hs])
(by { rw e.open_source.inter_frontier_eq, exact eq_on_empty _ _ })).replace_equiv
(e.to_local_equiv.disjoint_union e'.to_local_equiv Hs Ht)
(local_equiv.disjoint_union_eq_piecewise _ _ _ _).symm
end piecewise
section pi
variables {ι : Type*} [fintype ι] {Xi Yi : ι → Type*} [Π i, topological_space (Xi i)]
[Π i, topological_space (Yi i)] (ei : Π i, local_homeomorph (Xi i) (Yi i))
/-- The product of a finite family of `local_homeomorph`s. -/
@[simps to_local_equiv] def pi : local_homeomorph (Π i, Xi i) (Π i, Yi i) :=
{ to_local_equiv := local_equiv.pi (λ i, (ei i).to_local_equiv),
open_source := is_open_set_pi finite_univ $ λ i hi, (ei i).open_source,
open_target := is_open_set_pi finite_univ $ λ i hi, (ei i).open_target,
continuous_to_fun := continuous_on_pi.2 $ λ i, (ei i).continuous_on.comp
(continuous_apply _).continuous_on (λ f hf, hf i trivial),
continuous_inv_fun := continuous_on_pi.2 $ λ i, (ei i).continuous_on_symm.comp
(continuous_apply _).continuous_on (λ f hf, hf i trivial) }
end pi
section continuity
/-- Continuity within a set at a point can be read under right composition with a local
homeomorphism, if the point is in its target -/
lemma continuous_within_at_iff_continuous_within_at_comp_right
{f : β → γ} {s : set β} {x : β} (h : x ∈ e.target) :
continuous_within_at f s x ↔ continuous_within_at (f ∘ e) (e ⁻¹' s) (e.symm x) :=
by simp_rw [continuous_within_at, ← @tendsto_map'_iff _ _ _ _ e,
e.map_nhds_within_preimage_eq (e.map_target h), (∘), e.right_inv h]
/-- Continuity at a point can be read under right composition with a local homeomorphism, if the
point is in its target -/
lemma continuous_at_iff_continuous_at_comp_right
{f : β → γ} {x : β} (h : x ∈ e.target) :
continuous_at f x ↔ continuous_at (f ∘ e) (e.symm x) :=
by rw [← continuous_within_at_univ, e.continuous_within_at_iff_continuous_within_at_comp_right h,
preimage_univ, continuous_within_at_univ]
/-- A function is continuous on a set if and only if its composition with a local homeomorphism
on the right is continuous on the corresponding set. -/
lemma continuous_on_iff_continuous_on_comp_right {f : β → γ} {s : set β} (h : s ⊆ e.target) :
continuous_on f s ↔ continuous_on (f ∘ e) (e.source ∩ e ⁻¹' s) :=
begin
simp only [← e.symm_image_eq_source_inter_preimage h, continuous_on, ball_image_iff],
refine forall₂_congr (λ x hx, _),
rw [e.continuous_within_at_iff_continuous_within_at_comp_right (h hx),
e.symm_image_eq_source_inter_preimage h, inter_comm, continuous_within_at_inter],
exact is_open.mem_nhds e.open_source (e.map_target (h hx))
end
/-- Continuity within a set at a point can be read under left composition with a local
homeomorphism if a neighborhood of the initial point is sent to the source of the local
homeomorphism-/
lemma continuous_within_at_iff_continuous_within_at_comp_left
{f : γ → α} {s : set γ} {x : γ} (hx : f x ∈ e.source) (h : f ⁻¹' e.source ∈ 𝓝[s] x) :
continuous_within_at f s x ↔ continuous_within_at (e ∘ f) s x :=
begin
refine ⟨(e.continuous_at hx).tendsto.comp, λ fe_cont, _⟩,
rw [← continuous_within_at_inter' h] at fe_cont ⊢,
have : continuous_within_at (e.symm ∘ (e ∘ f)) (s ∩ f ⁻¹' e.source) x,
{ have : continuous_within_at e.symm univ (e (f x))
:= (e.continuous_at_symm (e.map_source hx)).continuous_within_at,
exact continuous_within_at.comp this fe_cont (subset_univ _) },
exact this.congr (λy hy, by simp [e.left_inv hy.2]) (by simp [e.left_inv hx])
end
/-- Continuity at a point can be read under left composition with a local homeomorphism if a
neighborhood of the initial point is sent to the source of the local homeomorphism-/
lemma continuous_at_iff_continuous_at_comp_left {f : γ → α} {x : γ} (h : f ⁻¹' e.source ∈ 𝓝 x) :
continuous_at f x ↔ continuous_at (e ∘ f) x :=
begin
have hx : f x ∈ e.source := (mem_of_mem_nhds h : _),
have h' : f ⁻¹' e.source ∈ 𝓝[univ] x, by rwa nhds_within_univ,
rw [← continuous_within_at_univ, ← continuous_within_at_univ,
e.continuous_within_at_iff_continuous_within_at_comp_left hx h']
end
/-- A function is continuous on a set if and only if its composition with a local homeomorphism
on the left is continuous on the corresponding set. -/
lemma continuous_on_iff_continuous_on_comp_left {f : γ → α} {s : set γ} (h : s ⊆ f ⁻¹' e.source) :
continuous_on f s ↔ continuous_on (e ∘ f) s :=
forall₂_congr $ λ x hx, e.continuous_within_at_iff_continuous_within_at_comp_left
(h hx) (mem_of_superset self_mem_nhds_within h)
/-- A function is continuous if and only if its composition with a local homeomorphism
on the left is continuous and its image is contained in the source. -/
lemma continuous_iff_continuous_comp_left {f : γ → α} (h : f ⁻¹' e.source = univ) :
continuous f ↔ continuous (e ∘ f) :=
begin
simp only [continuous_iff_continuous_on_univ],
exact e.continuous_on_iff_continuous_on_comp_left (eq.symm h).subset,
end
end continuity
/-- A local homeomrphism defines a homeomorphism between its source and target. -/
def to_homeomorph_source_target : e.source ≃ₜ e.target :=
{ to_fun := e.maps_to.restrict _ _ _,
inv_fun := e.symm_maps_to.restrict _ _ _,
left_inv := λ x, subtype.eq $ e.left_inv x.2,
right_inv := λ x, subtype.eq $ e.right_inv x.2,
continuous_to_fun := continuous_subtype_mk _ $
continuous_on_iff_continuous_restrict.1 e.continuous_on,
continuous_inv_fun := continuous_subtype_mk _ $
continuous_on_iff_continuous_restrict.1 e.symm.continuous_on }
lemma second_countable_topology_source [second_countable_topology β]
(e : local_homeomorph α β) :
second_countable_topology e.source :=
e.to_homeomorph_source_target.second_countable_topology
/-- If a local homeomorphism has source and target equal to univ, then it induces a homeomorphism
between the whole spaces, expressed in this definition. -/
@[simps apply symm_apply (mfld_cfg)]
def to_homeomorph_of_source_eq_univ_target_eq_univ (h : e.source = (univ : set α))
(h' : e.target = univ) : α ≃ₜ β :=
{ to_fun := e,
inv_fun := e.symm,
left_inv := λx, e.left_inv $ by { rw h, exact mem_univ _ },
right_inv := λx, e.right_inv $ by { rw h', exact mem_univ _ },
continuous_to_fun := begin
rw [continuous_iff_continuous_on_univ],
convert e.continuous_to_fun,
rw h
end,
continuous_inv_fun := begin
rw [continuous_iff_continuous_on_univ],
convert e.continuous_inv_fun,
rw h'
end }
/-- A local homeomorphism whose source is all of `α` defines an open embedding of `α` into `β`. The
converse is also true; see `open_embedding.to_local_homeomorph`. -/
lemma to_open_embedding (h : e.source = set.univ) : open_embedding e :=
begin
apply open_embedding_of_continuous_injective_open,
{ apply continuous_iff_continuous_on_univ.mpr,
rw ← h,
exact e.continuous_to_fun },
{ apply set.injective_iff_inj_on_univ.mpr,
rw ← h,
exact e.inj_on },
{ intros U hU,
simpa only [h, subset_univ] with mfld_simps using e.image_open_of_open hU}
end
end local_homeomorph
namespace homeomorph
variables (e : α ≃ₜ β) (e' : β ≃ₜ γ)
/- Register as simp lemmas that the fields of a local homeomorphism built from a homeomorphism
correspond to the fields of the original homeomorphism. -/
attribute [simps apply source target {simp_rhs := tt, .. mfld_cfg}] to_local_homeomorph
@[simp, mfld_simps] lemma to_local_homeomorph_coe_symm :
(e.to_local_homeomorph.symm : β → α) = e.symm := rfl
@[simp, mfld_simps] lemma refl_to_local_homeomorph :
(homeomorph.refl α).to_local_homeomorph = local_homeomorph.refl α := rfl
@[simp, mfld_simps] lemma symm_to_local_homeomorph :
e.symm.to_local_homeomorph = e.to_local_homeomorph.symm := rfl
@[simp, mfld_simps] lemma trans_to_local_homeomorph :
(e.trans e').to_local_homeomorph = e.to_local_homeomorph.trans e'.to_local_homeomorph :=
local_homeomorph.eq_of_local_equiv_eq $ equiv.trans_to_local_equiv _ _
end homeomorph
namespace open_embedding
variables (f : α → β) (h : open_embedding f)
/-- An open embedding of `α` into `β`, with `α` nonempty, defines a local homeomorphism whose source
is all of `α`. The converse is also true; see `local_homeomorph.to_open_embedding`. -/
@[simps apply source target (mfld_cfg)]
noncomputable def to_local_homeomorph [nonempty α] : local_homeomorph α β :=
local_homeomorph.of_continuous_open
((h.to_embedding.inj.inj_on univ).to_local_equiv _ _)
h.continuous.continuous_on h.is_open_map is_open_univ
lemma continuous_at_iff
{f : α → β} {g : β → γ} (hf : open_embedding f) {x : α} :
continuous_at (g ∘ f) x ↔ continuous_at g (f x) :=
begin
haveI : nonempty α := ⟨x⟩,
convert (((hf.to_local_homeomorph f).continuous_at_iff_continuous_at_comp_right) _).symm,
{ apply (local_homeomorph.left_inv _ _).symm,
simp, },
{ simp, },
end
end open_embedding
namespace topological_space.opens
open topological_space
variables (s : opens α) [nonempty s]
/-- The inclusion of an open subset `s` of a space `α` into `α` is a local homeomorphism from the
subtype `s` to `α`. -/
noncomputable def local_homeomorph_subtype_coe : local_homeomorph s α :=
open_embedding.to_local_homeomorph _ s.2.open_embedding_subtype_coe
@[simp, mfld_simps] lemma local_homeomorph_subtype_coe_coe :
(s.local_homeomorph_subtype_coe : s → α) = coe := rfl
@[simp, mfld_simps] lemma local_homeomorph_subtype_coe_source :
s.local_homeomorph_subtype_coe.source = set.univ := rfl
@[simp, mfld_simps] lemma local_homeomorph_subtype_coe_target :
s.local_homeomorph_subtype_coe.target = s :=
by { simp only [local_homeomorph_subtype_coe, subtype.range_coe_subtype] with mfld_simps, refl }
end topological_space.opens
namespace local_homeomorph
open topological_space
variables (e : local_homeomorph α β)
variables (s : opens α) [nonempty s]
/-- The restriction of a local homeomorphism `e` to an open subset `s` of the domain type produces a
local homeomorphism whose domain is the subtype `s`.-/
noncomputable def subtype_restr : local_homeomorph s β := s.local_homeomorph_subtype_coe.trans e
lemma subtype_restr_def : e.subtype_restr s = s.local_homeomorph_subtype_coe.trans e := rfl
@[simp, mfld_simps] lemma subtype_restr_coe : ((e.subtype_restr s : local_homeomorph s β) : s → β)
= set.restrict ↑s (e : α → β) := rfl
@[simp, mfld_simps] lemma subtype_restr_source : (e.subtype_restr s).source = coe ⁻¹' e.source :=
by simp only [subtype_restr_def] with mfld_simps
/- This lemma characterizes the transition functions of an open subset in terms of the transition
functions of the original space. -/
lemma subtype_restr_symm_trans_subtype_restr (f f' : local_homeomorph α β) :
(f.subtype_restr s).symm.trans (f'.subtype_restr s)
≈ (f.symm.trans f').restr (f.target ∩ (f.symm) ⁻¹' s) :=
begin
simp only [subtype_restr_def, trans_symm_eq_symm_trans_symm],
have openness₁ : is_open (f.target ∩ f.symm ⁻¹' s) := f.preimage_open_of_open_symm s.2,
rw [← of_set_trans _ openness₁, ← trans_assoc, ← trans_assoc],
refine eq_on_source.trans' _ (eq_on_source_refl _),
-- f' has been eliminated !!!
have sets_identity : f.symm.source ∩ (f.target ∩ (f.symm) ⁻¹' s) = f.symm.source ∩ f.symm ⁻¹' s,
{ mfld_set_tac },
have openness₂ : is_open (s : set α) := s.2,
rw [of_set_trans', sets_identity, ← trans_of_set' _ openness₂, trans_assoc],
refine eq_on_source.trans' (eq_on_source_refl _) _,
-- f has been eliminated !!!
refine setoid.trans (trans_symm_self s.local_homeomorph_subtype_coe) _,
simp only with mfld_simps,
end
end local_homeomorph
|
3b6d18befda5e698c4fde5cd62d2f58d07c0fde8 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/analysis/locally_convex/weak_dual.lean | 6eb8b71ed36e2e3dfe13fd78b2c18fb1b6bb8623 | [
"Apache-2.0"
] | permissive | jcommelin/mathlib | d8456447c36c176e14d96d9e76f39841f69d2d9b | ee8279351a2e434c2852345c51b728d22af5a156 | refs/heads/master | 1,664,782,136,488 | 1,663,638,983,000 | 1,663,638,983,000 | 132,563,656 | 0 | 0 | Apache-2.0 | 1,663,599,929,000 | 1,525,760,539,000 | Lean | UTF-8 | Lean | false | false | 5,465 | lean | /-
Copyright (c) 2022 Moritz Doll. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Moritz Doll
-/
import topology.algebra.module.weak_dual
import analysis.normed.field.basic
import analysis.locally_convex.with_seminorms
/-!
# Weak Dual in Topological Vector Spaces
We prove that the weak topology induced by a bilinear form `B : E →ₗ[𝕜] F →ₗ[𝕜] 𝕜` is locally
convex and we explicit give a neighborhood basis in terms of the family of seminorms `λ x, ∥B x y∥`
for `y : F`.
## Main definitions
* `linear_map.to_seminorm`: turn a linear form `f : E →ₗ[𝕜] 𝕜` into a seminorm `λ x, ∥f x∥`.
* `linear_map.to_seminorm_family`: turn a bilinear form `B : E →ₗ[𝕜] F →ₗ[𝕜] 𝕜` into a map
`F → seminorm 𝕜 E`.
## Main statements
* `linear_map.has_basis_weak_bilin`: the seminorm balls of `B.to_seminorm_family` form a
neighborhood basis of `0` in the weak topology.
* `linear_map.to_seminorm_family.with_seminorms`: the topology of a weak space is induced by the
family of seminorm `B.to_seminorm_family`.
* `weak_bilin.locally_convex_space`: a spaced endowed with a weak topology is locally convex.
## References
* [Bourbaki, *Topological Vector Spaces*][bourbaki1987]
## Tags
weak dual, seminorm
-/
variables {𝕜 E F ι : Type*}
open_locale topological_space
section bilin_form
namespace linear_map
variables [normed_field 𝕜] [add_comm_group E] [module 𝕜 E] [add_comm_group F] [module 𝕜 F]
/-- Construct a seminorm from a linear form `f : E →ₗ[𝕜] 𝕜` over a normed field `𝕜` by
`λ x, ∥f x∥` -/
def to_seminorm (f : E →ₗ[𝕜] 𝕜) : seminorm 𝕜 E :=
(norm_seminorm 𝕜 𝕜).comp f
lemma coe_to_seminorm {f : E →ₗ[𝕜] 𝕜} :
⇑f.to_seminorm = λ x, ∥f x∥ := rfl
@[simp] lemma to_seminorm_apply {f : E →ₗ[𝕜] 𝕜} {x : E} :
f.to_seminorm x = ∥f x∥ := rfl
lemma to_seminorm_ball_zero {f : E →ₗ[𝕜] 𝕜} {r : ℝ} :
seminorm.ball f.to_seminorm 0 r = { x : E | ∥f x∥ < r} :=
by simp only [seminorm.ball_zero_eq, to_seminorm_apply]
lemma to_seminorm_comp (f : F →ₗ[𝕜] 𝕜) (g : E →ₗ[𝕜] F) :
f.to_seminorm.comp g = (f.comp g).to_seminorm :=
by { ext, simp only [seminorm.comp_apply, to_seminorm_apply, coe_comp] }
/-- Construct a family of seminorms from a bilinear form. -/
def to_seminorm_family (B : E →ₗ[𝕜] F →ₗ[𝕜] 𝕜) : seminorm_family 𝕜 E F :=
λ y, (B.flip y).to_seminorm
@[simp] lemma to_seminorm_family_apply {B : E →ₗ[𝕜] F →ₗ[𝕜] 𝕜} {x y} :
(B.to_seminorm_family y) x = ∥B x y∥ := rfl
end linear_map
end bilin_form
section topology
variables [normed_field 𝕜] [add_comm_group E] [module 𝕜 E] [add_comm_group F] [module 𝕜 F]
variables [nonempty ι]
variables {B : E →ₗ[𝕜] F →ₗ[𝕜] 𝕜}
lemma linear_map.has_basis_weak_bilin (B : E →ₗ[𝕜] F →ₗ[𝕜] 𝕜) :
(𝓝 (0 : weak_bilin B)).has_basis B.to_seminorm_family.basis_sets id :=
begin
let p := B.to_seminorm_family,
rw [nhds_induced, nhds_pi],
simp only [map_zero, linear_map.zero_apply],
have h := @metric.nhds_basis_ball 𝕜 _ 0,
have h' := filter.has_basis_pi (λ (i : F), h),
have h'' := filter.has_basis.comap (λ x y, B x y) h',
refine h''.to_has_basis _ _,
{ rintros (U : set F × (F → ℝ)) hU,
cases hU with hU₁ hU₂,
simp only [id.def],
let U' := hU₁.to_finset,
by_cases hU₃ : U.fst.nonempty,
{ have hU₃' : U'.nonempty := hU₁.nonempty_to_finset.mpr hU₃,
refine ⟨(U'.sup p).ball 0 $ U'.inf' hU₃' U.snd, p.basis_sets_mem _ $
(finset.lt_inf'_iff _).2 $ λ y hy, hU₂ y $ (hU₁.mem_to_finset).mp hy, λ x hx y hy, _⟩,
simp only [set.mem_preimage, set.mem_pi, mem_ball_zero_iff],
rw seminorm.mem_ball_zero at hx,
rw ←linear_map.to_seminorm_family_apply,
have hyU' : y ∈ U' := (set.finite.mem_to_finset hU₁).mpr hy,
have hp : p y ≤ U'.sup p := finset.le_sup hyU',
refine lt_of_le_of_lt (hp x) (lt_of_lt_of_le hx _),
exact finset.inf'_le _ hyU' },
rw set.not_nonempty_iff_eq_empty.mp hU₃,
simp only [set.empty_pi, set.preimage_univ, set.subset_univ, and_true],
exact Exists.intro ((p 0).ball 0 1) (p.basis_sets_singleton_mem 0 one_pos) },
rintros U (hU : U ∈ p.basis_sets),
rw seminorm_family.basis_sets_iff at hU,
rcases hU with ⟨s, r, hr, hU⟩,
rw hU,
refine ⟨(s, λ _, r), ⟨by simp only [s.finite_to_set], λ y hy, hr⟩, λ x hx, _⟩,
simp only [set.mem_preimage, set.mem_pi, finset.mem_coe, mem_ball_zero_iff] at hx,
simp only [id.def, seminorm.mem_ball, sub_zero],
refine seminorm.finset_sup_apply_lt hr (λ y hy, _),
rw linear_map.to_seminorm_family_apply,
exact hx y hy,
end
lemma linear_map.weak_bilin_with_seminorms (B : E →ₗ[𝕜] F →ₗ[𝕜] 𝕜) :
with_seminorms (linear_map.to_seminorm_family B : F → seminorm 𝕜 (weak_bilin B)) :=
seminorm_family.with_seminorms_of_has_basis _ B.has_basis_weak_bilin
end topology
section locally_convex
variables [normed_field 𝕜] [add_comm_group E] [module 𝕜 E] [add_comm_group F] [module 𝕜 F]
variables [nonempty ι] [normed_space ℝ 𝕜] [module ℝ E] [is_scalar_tower ℝ 𝕜 E]
instance {B : E →ₗ[𝕜] F →ₗ[𝕜] 𝕜} : locally_convex_space ℝ (weak_bilin B) :=
seminorm_family.to_locally_convex_space (B.weak_bilin_with_seminorms)
end locally_convex
|
5e4c9d913418c6c60a5aa34989cf8bc2c6ff38dd | 2c41ae31b2b771ad5646ad880201393f5269a7f0 | /Lean/Qualities/PhysicalCapable.lean | 19c4c3e05e0a6157895c06d6b1830715a63d409a | [] | no_license | kevinsullivan/Boehm | 926f25bc6f1a8b6bd47d333d936fdfc278228312 | 55208395bff20d48a598b7fa33a4d55a2447a9cf | refs/heads/master | 1,586,127,134,302 | 1,488,252,326,000 | 1,488,252,326,000 | 32,836,930 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 444 | lean | import SystemModel.System
inductive PhysicalCapable (sys_type: SystemType): Prop
| intro : (exists physicalCapable: sys_type ^.Contexts -> sys_type ^.Phases -> sys_type ^.Stakeholders -> @SystemInstance sys_type -> Prop,
forall c: sys_type ^.Contexts, forall p: sys_type ^.Phases,
forall s: sys_type ^.Stakeholders, forall st: @SystemInstance sys_type, physicalCapable c p s st) ->
PhysicalCapable
|
af6c9e497c53a1abc57ee6c56335ffb6d61d28dd | 4d2583807a5ac6caaffd3d7a5f646d61ca85d532 | /src/data/pequiv.lean | 25da6ab36ec36248b1be73a3398933d5a8e73a5f | [
"Apache-2.0"
] | permissive | AntoineChambert-Loir/mathlib | 64aabb896129885f12296a799818061bc90da1ff | 07be904260ab6e36a5769680b6012f03a4727134 | refs/heads/master | 1,693,187,631,771 | 1,636,719,886,000 | 1,636,719,886,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 13,664 | lean | /-
Copyright (c) 2019 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes
-/
import data.set.lattice
/-!
# Partial Equivalences
In this file, we define partial equivalences `pequiv`, which are a bijection between a subset of `α`
and a subset of `β`. Notationally, a `pequiv` is denoted by "`≃.`" (note that the full stop is part
of the notation). The way we store these internally is with two functions `f : α → option β` and
the reverse function `g : β → option α`, with the condition that if `f a` is `option.some b`,
then `g b` is `option.some a`.
## Main results
- `pequiv.of_set`: creates a `pequiv` from a set `s`,
which sends an element to itself if it is in `s`.
- `pequiv.single`: given two elements `a : α` and `b : β`, create a `pequiv` that sends them to
each other, and ignores all other elements.
- `pequiv.injective_of_forall_ne_is_some`/`injective_of_forall_is_some`: If the domain of a `pequiv`
is all of `α` (except possibly one point), its `to_fun` is injective.
## Canonical order
`pequiv` is canonically ordered by inclusion; that is, if a function `f` defined on a subset `s`
is equal to `g` on that subset, but `g` is also defined on a larger set, then `f ≤ g`. We also have
a definition of `⊥`, which is the empty `pequiv` (sends all to `none`), which in the end gives us a
`semilattice_inf_bot` instance.
## Tags
pequiv, partial equivalence
-/
universes u v w x
/-- A `pequiv` is a partial equivalence, a representation of a bijection between a subset
of `α` and a subset of `β`. See also `local_equiv` for a version that requires `to_fun` and
`inv_fun` to be globally defined functions and has `source` and `target` sets as extra fields. -/
structure pequiv (α : Type u) (β : Type v) :=
(to_fun : α → option β)
(inv_fun : β → option α)
(inv : ∀ (a : α) (b : β), a ∈ inv_fun b ↔ b ∈ to_fun a)
infixr ` ≃. `:25 := pequiv
namespace pequiv
variables {α : Type u} {β : Type v} {γ : Type w} {δ : Type x}
open function option
instance : has_coe_to_fun (α ≃. β) (λ _, α → option β) := ⟨to_fun⟩
@[simp] lemma coe_mk_apply (f₁ : α → option β) (f₂ : β → option α) (h) (x : α) :
(pequiv.mk f₁ f₂ h : α → option β) x = f₁ x := rfl
@[ext] lemma ext : ∀ {f g : α ≃. β} (h : ∀ x, f x = g x), f = g
| ⟨f₁, f₂, hf⟩ ⟨g₁, g₂, hg⟩ h :=
have h : f₁ = g₁, from funext h,
have ∀ b, f₂ b = g₂ b,
begin
subst h,
assume b,
have hf := λ a, hf a b,
have hg := λ a, hg a b,
cases h : g₂ b with a,
{ simp only [h, option.not_mem_none, false_iff] at hg,
simp only [hg, iff_false] at hf,
rwa [option.eq_none_iff_forall_not_mem] },
{ rw [← option.mem_def, hf, ← hg, h, option.mem_def] }
end,
by simp [*, funext_iff]
lemma ext_iff {f g : α ≃. β} : f = g ↔ ∀ x, f x = g x :=
⟨congr_fun ∘ congr_arg _, ext⟩
/-- The identity map as a partial equivalence. -/
@[refl] protected def refl (α : Type*) : α ≃. α :=
{ to_fun := some,
inv_fun := some,
inv := λ _ _, eq_comm }
/-- The inverse partial equivalence. -/
@[symm] protected def symm (f : α ≃. β) : β ≃. α :=
{ to_fun := f.2,
inv_fun := f.1,
inv := λ _ _, (f.inv _ _).symm }
lemma mem_iff_mem (f : α ≃. β) : ∀ {a : α} {b : β}, a ∈ f.symm b ↔ b ∈ f a := f.3
lemma eq_some_iff (f : α ≃. β) : ∀ {a : α} {b : β}, f.symm b = some a ↔ f a = some b := f.3
/-- Composition of partial equivalences `f : α ≃. β` and `g : β ≃. γ`. -/
@[trans] protected def trans (f : α ≃. β) (g : β ≃. γ) : α ≃. γ :=
{ to_fun := λ a, (f a).bind g,
inv_fun := λ a, (g.symm a).bind f.symm,
inv := λ a b, by simp [*, and.comm, eq_some_iff f, eq_some_iff g] at * }
@[simp] lemma refl_apply (a : α) : pequiv.refl α a = some a := rfl
@[simp] lemma symm_refl : (pequiv.refl α).symm = pequiv.refl α := rfl
@[simp] lemma symm_symm (f : α ≃. β) : f.symm.symm = f := by cases f; refl
lemma symm_injective : function.injective (@pequiv.symm α β) :=
left_inverse.injective symm_symm
lemma trans_assoc (f : α ≃. β) (g : β ≃. γ) (h : γ ≃. δ) :
(f.trans g).trans h = f.trans (g.trans h) :=
ext (λ _, option.bind_assoc _ _ _)
lemma mem_trans (f : α ≃. β) (g : β ≃. γ) (a : α) (c : γ) :
c ∈ f.trans g a ↔ ∃ b, b ∈ f a ∧ c ∈ g b := option.bind_eq_some'
lemma trans_eq_some (f : α ≃. β) (g : β ≃. γ) (a : α) (c : γ) :
f.trans g a = some c ↔ ∃ b, f a = some b ∧ g b = some c := option.bind_eq_some'
lemma trans_eq_none (f : α ≃. β) (g : β ≃. γ) (a : α) :
f.trans g a = none ↔ (∀ b c, b ∉ f a ∨ c ∉ g b) :=
begin
simp only [eq_none_iff_forall_not_mem, mem_trans, imp_iff_not_or.symm],
push_neg, tauto
end
@[simp] lemma refl_trans (f : α ≃. β) : (pequiv.refl α).trans f = f :=
by ext; dsimp [pequiv.trans]; refl
@[simp] lemma trans_refl (f : α ≃. β) : f.trans (pequiv.refl β) = f :=
by ext; dsimp [pequiv.trans]; simp
protected lemma inj (f : α ≃. β) {a₁ a₂ : α} {b : β} (h₁ : b ∈ f a₁) (h₂ : b ∈ f a₂) : a₁ = a₂ :=
by rw ← mem_iff_mem at *; cases h : f.symm b; simp * at *
/-- If the domain of a `pequiv` is `α` except a point, its forward direction is injective. -/
lemma injective_of_forall_ne_is_some (f : α ≃. β) (a₂ : α)
(h : ∀ (a₁ : α), a₁ ≠ a₂ → is_some (f a₁)) : injective f :=
has_left_inverse.injective
⟨λ b, option.rec_on b a₂ (λ b', option.rec_on (f.symm b') a₂ id),
λ x, begin
classical,
cases hfx : f x,
{ have : x = a₂, from not_imp_comm.1 (h x) (hfx.symm ▸ by simp), simp [this] },
{ simp only [hfx], rw [(eq_some_iff f).2 hfx], refl }
end⟩
/-- If the domain of a `pequiv` is all of `α`, its forward direction is injective. -/
lemma injective_of_forall_is_some {f : α ≃. β}
(h : ∀ (a : α), is_some (f a)) : injective f :=
(classical.em (nonempty α)).elim
(λ hn, injective_of_forall_ne_is_some f (classical.choice hn)
(λ a _, h a))
(λ hn x, (hn ⟨x⟩).elim)
section of_set
variables (s : set α) [decidable_pred (∈ s)]
/-- Creates a `pequiv` that is the identity on `s`, and `none` outside of it. -/
def of_set (s : set α) [decidable_pred (∈ s)] : α ≃. α :=
{ to_fun := λ a, if a ∈ s then some a else none,
inv_fun := λ a, if a ∈ s then some a else none,
inv := λ a b, by {
split_ifs with hb ha ha,
{ simp [eq_comm] },
{ simp [ne_of_mem_of_not_mem hb ha] },
{ simp [ne_of_mem_of_not_mem ha hb] },
{ simp } } }
lemma mem_of_set_self_iff {s : set α} [decidable_pred (∈ s)] {a : α} : a ∈ of_set s a ↔ a ∈ s :=
by dsimp [of_set]; split_ifs; simp *
lemma mem_of_set_iff {s : set α} [decidable_pred (∈ s)] {a b : α} :
a ∈ of_set s b ↔ a = b ∧ a ∈ s :=
begin
dsimp [of_set],
split_ifs,
{ simp only [iff_self_and, option.mem_def, eq_comm],
rintro rfl,
exact h, },
{ simp only [false_iff, not_and, option.not_mem_none],
rintro rfl,
exact h, }
end
@[simp] lemma of_set_eq_some_iff {s : set α} {h : decidable_pred (∈ s)} {a b : α} :
of_set s b = some a ↔ a = b ∧ a ∈ s := mem_of_set_iff
@[simp] lemma of_set_eq_some_self_iff {s : set α} {h : decidable_pred (∈ s)} {a : α} :
of_set s a = some a ↔ a ∈ s := mem_of_set_self_iff
@[simp] lemma of_set_symm : (of_set s).symm = of_set s := rfl
@[simp] lemma of_set_univ : of_set set.univ = pequiv.refl α := rfl
@[simp] lemma of_set_eq_refl {s : set α} [decidable_pred (∈ s)] :
of_set s = pequiv.refl α ↔ s = set.univ :=
⟨λ h, begin
rw [set.eq_univ_iff_forall],
intro,
rw [← mem_of_set_self_iff, h],
exact rfl
end, λ h, by simp only [of_set_univ.symm, h]; congr⟩
end of_set
lemma symm_trans_rev (f : α ≃. β) (g : β ≃. γ) : (f.trans g).symm = g.symm.trans f.symm := rfl
lemma trans_symm (f : α ≃. β) : f.trans f.symm = of_set {a | (f a).is_some} :=
begin
ext,
dsimp [pequiv.trans],
simp only [eq_some_iff f, option.is_some_iff_exists, option.mem_def, bind_eq_some',
of_set_eq_some_iff],
split,
{ rintros ⟨b, hb₁, hb₂⟩,
exact ⟨pequiv.inj _ hb₂ hb₁, b, hb₂⟩ },
{ simp {contextual := tt} }
end
lemma symm_trans (f : α ≃. β) : f.symm.trans f = of_set {b | (f.symm b).is_some} :=
symm_injective $ by simp [symm_trans_rev, trans_symm, -symm_symm]
lemma trans_symm_eq_iff_forall_is_some {f : α ≃. β} :
f.trans f.symm = pequiv.refl α ↔ ∀ a, is_some (f a) :=
by rw [trans_symm, of_set_eq_refl, set.eq_univ_iff_forall]; refl
instance : has_bot (α ≃. β) :=
⟨{ to_fun := λ _, none,
inv_fun := λ _, none,
inv := by simp }⟩
instance : inhabited (α ≃. β) := ⟨⊥⟩
@[simp] lemma bot_apply (a : α) : (⊥ : α ≃. β) a = none := rfl
@[simp] lemma symm_bot : (⊥ : α ≃. β).symm = ⊥ := rfl
@[simp] lemma trans_bot (f : α ≃. β) : f.trans (⊥ : β ≃. γ) = ⊥ :=
by ext; dsimp [pequiv.trans]; simp
@[simp] lemma bot_trans (f : β ≃. γ) : (⊥ : α ≃. β).trans f = ⊥ :=
by ext; dsimp [pequiv.trans]; simp
lemma is_some_symm_get (f : α ≃. β) {a : α} (h : is_some (f a)) :
is_some (f.symm (option.get h)) :=
is_some_iff_exists.2 ⟨a, by rw [f.eq_some_iff, some_get]⟩
section single
variables [decidable_eq α] [decidable_eq β] [decidable_eq γ]
/-- Create a `pequiv` which sends `a` to `b` and `b` to `a`, but is otherwise `none`. -/
def single (a : α) (b : β) : α ≃. β :=
{ to_fun := λ x, if x = a then some b else none,
inv_fun := λ x, if x = b then some a else none,
inv := λ _ _, by simp; split_ifs; cc }
lemma mem_single (a : α) (b : β) : b ∈ single a b a := if_pos rfl
lemma mem_single_iff (a₁ a₂ : α) (b₁ b₂ : β) : b₁ ∈ single a₂ b₂ a₁ ↔ a₁ = a₂ ∧ b₁ = b₂ :=
by dsimp [single]; split_ifs; simp [*, eq_comm]
@[simp] lemma symm_single (a : α) (b : β) : (single a b).symm = single b a := rfl
@[simp] lemma single_apply (a : α) (b : β) : single a b a = some b := if_pos rfl
lemma single_apply_of_ne {a₁ a₂ : α} (h : a₁ ≠ a₂) (b : β) : single a₁ b a₂ = none := if_neg h.symm
lemma single_trans_of_mem (a : α) {b : β} {c : γ} {f : β ≃. γ} (h : c ∈ f b) :
(single a b).trans f = single a c :=
begin
ext,
dsimp [single, pequiv.trans],
split_ifs; simp * at *
end
lemma trans_single_of_mem {a : α} {b : β} (c : γ) {f : α ≃. β} (h : b ∈ f a) :
f.trans (single b c) = single a c :=
symm_injective $ single_trans_of_mem _ ((mem_iff_mem f).2 h)
@[simp]
lemma single_trans_single (a : α) (b : β) (c : γ) : (single a b).trans (single b c) = single a c :=
single_trans_of_mem _ (mem_single _ _)
@[simp] lemma single_subsingleton_eq_refl [subsingleton α] (a b : α) : single a b = pequiv.refl α :=
begin
ext i j,
dsimp [single],
rw [if_pos (subsingleton.elim i a), subsingleton.elim i j, subsingleton.elim b j]
end
lemma trans_single_of_eq_none {b : β} (c : γ) {f : δ ≃. β} (h : f.symm b = none) :
f.trans (single b c) = ⊥ :=
begin
ext,
simp only [eq_none_iff_forall_not_mem, option.mem_def, f.eq_some_iff] at h,
dsimp [pequiv.trans, single],
simp,
intros,
split_ifs;
simp * at *
end
lemma single_trans_of_eq_none (a : α) {b : β} {f : β ≃. δ} (h : f b = none) :
(single a b).trans f = ⊥ :=
symm_injective $ trans_single_of_eq_none _ h
lemma single_trans_single_of_ne {b₁ b₂ : β} (h : b₁ ≠ b₂) (a : α) (c : γ) :
(single a b₁).trans (single b₂ c) = ⊥ :=
single_trans_of_eq_none _ (single_apply_of_ne h.symm _)
end single
section order
instance : partial_order (α ≃. β) :=
{ le := λ f g, ∀ (a : α) (b : β), b ∈ f a → b ∈ g a,
le_refl := λ _ _ _, id,
le_trans := λ f g h fg gh a b, (gh a b) ∘ (fg a b),
le_antisymm := λ f g fg gf, ext begin
assume a,
cases h : g a with b,
{ exact eq_none_iff_forall_not_mem.2
(λ b hb, option.not_mem_none b $ h ▸ fg a b hb) },
{ exact gf _ _ h }
end }
lemma le_def {f g : α ≃. β} : f ≤ g ↔ (∀ (a : α) (b : β), b ∈ f a → b ∈ g a) := iff.rfl
instance : order_bot (α ≃. β) :=
{ bot_le := λ _ _ _ h, (not_mem_none _ h).elim,
..pequiv.partial_order,
..pequiv.has_bot }
instance [decidable_eq α] [decidable_eq β] : semilattice_inf_bot (α ≃. β) :=
{ inf := λ f g,
{ to_fun := λ a, if f a = g a then f a else none,
inv_fun := λ b, if f.symm b = g.symm b then f.symm b else none,
inv := λ a b, begin
have := @mem_iff_mem _ _ f a b,
have := @mem_iff_mem _ _ g a b,
split_ifs; finish
end },
inf_le_left := λ _ _ _ _, by simp; split_ifs; cc,
inf_le_right := λ _ _ _ _, by simp; split_ifs; cc,
le_inf := λ f g h fg gh a b, begin
have := fg a b,
have := gh a b,
simp [le_def],
split_ifs; finish
end,
..pequiv.order_bot,
..pequiv.partial_order }
end order
end pequiv
namespace equiv
variables {α : Type*} {β : Type*} {γ : Type*}
/-- Turns an `equiv` into a `pequiv` of the whole type. -/
def to_pequiv (f : α ≃ β) : α ≃. β :=
{ to_fun := some ∘ f,
inv_fun := some ∘ f.symm,
inv := by simp [equiv.eq_symm_apply, eq_comm] }
@[simp] lemma to_pequiv_refl : (equiv.refl α).to_pequiv = pequiv.refl α := rfl
lemma to_pequiv_trans (f : α ≃ β) (g : β ≃ γ) : (f.trans g).to_pequiv =
f.to_pequiv.trans g.to_pequiv := rfl
lemma to_pequiv_symm (f : α ≃ β) : f.symm.to_pequiv = f.to_pequiv.symm := rfl
lemma to_pequiv_apply (f : α ≃ β) (x : α) : f.to_pequiv x = some (f x) := rfl
end equiv
|
7b2df50a491a241a0c54b3d595730934d0bfede0 | 432d948a4d3d242fdfb44b81c9e1b1baacd58617 | /src/data/nat/basic.lean | bcec3462cb01118437a9499511e8e0c8f952dcd1 | [
"Apache-2.0"
] | permissive | JLimperg/aesop3 | 306cc6570c556568897ed2e508c8869667252e8a | a4a116f650cc7403428e72bd2e2c4cda300fe03f | refs/heads/master | 1,682,884,916,368 | 1,620,320,033,000 | 1,620,320,033,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 69,413 | lean | /-
Copyright (c) 2014 Floris van Doorn (c) 2016 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Floris van Doorn, Leonardo de Moura, Jeremy Avigad, Mario Carneiro
-/
import algebra.group.hom_instances
import algebra.order_functions
import algebra.ordered_ring
import algebra.group_power.order
/-!
# Basic operations on the natural numbers
This file contains:
- instances on the natural numbers
- some basic lemmas about natural numbers
- extra recursors:
* `le_rec_on`, `le_induction`: recursion and induction principles starting at non-zero numbers
* `decreasing_induction`: recursion growing downwards
* `strong_rec'`: recursion based on strong inequalities
- decidability instances on predicates about the natural numbers
-/
universes u v
/-! ### instances -/
instance : nontrivial ℕ :=
⟨⟨0, 1, nat.zero_ne_one⟩⟩
instance : comm_semiring nat :=
{ add := nat.add,
add_assoc := nat.add_assoc,
zero := nat.zero,
zero_add := nat.zero_add,
add_zero := nat.add_zero,
add_comm := nat.add_comm,
mul := nat.mul,
mul_assoc := nat.mul_assoc,
one := nat.succ nat.zero,
one_mul := nat.one_mul,
mul_one := nat.mul_one,
left_distrib := nat.left_distrib,
right_distrib := nat.right_distrib,
zero_mul := nat.zero_mul,
mul_zero := nat.mul_zero,
mul_comm := nat.mul_comm,
nsmul := λ m n, m * n,
nsmul_zero' := nat.zero_mul,
nsmul_succ' := λ n x, by rw [nat.succ_eq_one_add, nat.right_distrib, nat.one_mul] }
instance : linear_ordered_semiring nat :=
{ add_left_cancel := @nat.add_left_cancel,
lt := nat.lt,
add_le_add_left := @nat.add_le_add_left,
le_of_add_le_add_left := @nat.le_of_add_le_add_left,
zero_le_one := nat.le_of_lt (nat.zero_lt_succ 0),
mul_lt_mul_of_pos_left := @nat.mul_lt_mul_of_pos_left,
mul_lt_mul_of_pos_right := @nat.mul_lt_mul_of_pos_right,
decidable_eq := nat.decidable_eq,
exists_pair_ne := ⟨0, 1, ne_of_lt nat.zero_lt_one⟩,
..nat.comm_semiring, ..nat.linear_order }
-- all the fields are already included in the linear_ordered_semiring instance
instance : linear_ordered_cancel_add_comm_monoid ℕ :=
{ add_left_cancel := @nat.add_left_cancel,
..nat.linear_ordered_semiring }
instance : linear_ordered_comm_monoid_with_zero ℕ :=
{ mul_le_mul_left := λ a b h c, nat.mul_le_mul_left c h,
..nat.linear_ordered_semiring,
..(infer_instance : comm_monoid_with_zero ℕ)}
/-! Extra instances to short-circuit type class resolution -/
instance : add_comm_monoid nat := by apply_instance
instance : add_monoid nat := by apply_instance
instance : monoid nat := by apply_instance
instance : comm_monoid nat := by apply_instance
instance : comm_semigroup nat := by apply_instance
instance : semigroup nat := by apply_instance
instance : add_comm_semigroup nat := by apply_instance
instance : add_semigroup nat := by apply_instance
instance : distrib nat := by apply_instance
instance : semiring nat := by apply_instance
instance : ordered_semiring nat := by apply_instance
instance : canonically_ordered_comm_semiring ℕ :=
{ le_iff_exists_add := assume a b,
⟨assume h, let ⟨c, hc⟩ := nat.le.dest h in ⟨c, hc.symm⟩,
assume ⟨c, hc⟩, hc.symm ▸ nat.le_add_right _ _⟩,
eq_zero_or_eq_zero_of_mul_eq_zero := assume a b, nat.eq_zero_of_mul_eq_zero,
bot := 0,
bot_le := nat.zero_le,
.. nat.nontrivial,
.. (infer_instance : ordered_add_comm_monoid ℕ),
.. (infer_instance : linear_ordered_semiring ℕ),
.. (infer_instance : comm_semiring ℕ) }
instance : canonically_linear_ordered_add_monoid ℕ :=
{ .. (infer_instance : canonically_ordered_add_monoid ℕ),
.. nat.linear_order }
instance nat.subtype.semilattice_sup_bot (s : set ℕ) [decidable_pred s] [h : nonempty s] :
semilattice_sup_bot s :=
{ bot := ⟨nat.find (nonempty_subtype.1 h), nat.find_spec (nonempty_subtype.1 h)⟩,
bot_le := λ x, nat.find_min' _ x.2,
..subtype.linear_order s,
..lattice_of_linear_order }
theorem nat.eq_of_mul_eq_mul_right {n m k : ℕ} (Hm : 0 < m) (H : n * m = k * m) : n = k :=
by rw [mul_comm n m, mul_comm k m] at H; exact nat.eq_of_mul_eq_mul_left Hm H
instance nat.comm_cancel_monoid_with_zero : comm_cancel_monoid_with_zero ℕ :=
{ mul_left_cancel_of_ne_zero :=
λ _ _ _ h1 h2, nat.eq_of_mul_eq_mul_left (nat.pos_of_ne_zero h1) h2,
mul_right_cancel_of_ne_zero :=
λ _ _ _ h1 h2, nat.eq_of_mul_eq_mul_right (nat.pos_of_ne_zero h1) h2,
.. (infer_instance : comm_monoid_with_zero ℕ) }
attribute [simp] nat.not_lt_zero nat.succ_ne_zero nat.succ_ne_self
nat.zero_ne_one nat.one_ne_zero
nat.zero_ne_bit1 nat.bit1_ne_zero
nat.bit0_ne_one nat.one_ne_bit0
nat.bit0_ne_bit1 nat.bit1_ne_bit0
/-!
Inject some simple facts into the type class system.
This `fact` should not be confused with the factorial function `nat.fact`!
-/
section facts
instance succ_pos'' (n : ℕ) : fact (0 < n.succ) := ⟨n.succ_pos⟩
instance pos_of_one_lt (n : ℕ) [h : fact (1 < n)] : fact (0 < n) :=
⟨lt_trans zero_lt_one h.1⟩
end facts
variables {m n k : ℕ}
namespace nat
/-!
### Recursion and `set.range`
-/
section set
open set
theorem zero_union_range_succ : {0} ∪ range succ = univ :=
by { ext n, cases n; simp }
variables {α : Type*}
theorem range_of_succ (f : ℕ → α) : {f 0} ∪ range (f ∘ succ) = range f :=
by rw [← image_singleton, range_comp, ← image_union, zero_union_range_succ, image_univ]
theorem range_rec {α : Type*} (x : α) (f : ℕ → α → α) :
(set.range (λ n, nat.rec x f n) : set α) =
{x} ∪ set.range (λ n, nat.rec (f 0 x) (f ∘ succ) n) :=
begin
convert (range_of_succ _).symm,
ext n,
induction n with n ihn,
{ refl },
{ dsimp at ihn ⊢,
rw ihn }
end
theorem range_cases_on {α : Type*} (x : α) (f : ℕ → α) :
(set.range (λ n, nat.cases_on n x f) : set α) = {x} ∪ set.range f :=
(range_of_succ _).symm
end set
/-! ### The units of the natural numbers as a `monoid` and `add_monoid` -/
theorem units_eq_one (u : units ℕ) : u = 1 :=
units.ext $ nat.eq_one_of_dvd_one ⟨u.inv, u.val_inv.symm⟩
theorem add_units_eq_zero (u : add_units ℕ) : u = 0 :=
add_units.ext $ (nat.eq_zero_of_add_eq_zero u.val_neg).1
@[simp] protected theorem is_unit_iff {n : ℕ} : is_unit n ↔ n = 1 :=
iff.intro
(assume ⟨u, hu⟩, match n, u, hu, nat.units_eq_one u with _, _, rfl, rfl := rfl end)
(assume h, h.symm ▸ ⟨1, rfl⟩)
/-! ### Equalities and inequalities involving zero and one -/
lemma one_lt_iff_ne_zero_and_ne_one : ∀ {n : ℕ}, 1 < n ↔ n ≠ 0 ∧ n ≠ 1
| 0 := dec_trivial
| 1 := dec_trivial
| (n+2) := dec_trivial
protected theorem mul_ne_zero {n m : ℕ} (n0 : n ≠ 0) (m0 : m ≠ 0) : n * m ≠ 0
| nm := (eq_zero_of_mul_eq_zero nm).elim n0 m0
@[simp] protected theorem mul_eq_zero {a b : ℕ} : a * b = 0 ↔ a = 0 ∨ b = 0 :=
iff.intro eq_zero_of_mul_eq_zero (by simp [or_imp_distrib] {contextual := tt})
@[simp] protected theorem zero_eq_mul {a b : ℕ} : 0 = a * b ↔ a = 0 ∨ b = 0 :=
by rw [eq_comm, nat.mul_eq_zero]
lemma eq_zero_of_double_le {a : ℕ} (h : 2 * a ≤ a) : a = 0 :=
nat.eq_zero_of_le_zero $
by rwa [two_mul, nat.add_le_to_le_sub, nat.sub_self] at h; refl
lemma eq_zero_of_mul_le {a b : ℕ} (hb : 2 ≤ b) (h : b * a ≤ a) : a = 0 :=
eq_zero_of_double_le $ le_trans (nat.mul_le_mul_right _ hb) h
theorem le_zero_iff {i : ℕ} : i ≤ 0 ↔ i = 0 :=
⟨nat.eq_zero_of_le_zero, assume h, h ▸ le_refl i⟩
lemma zero_max {m : ℕ} : max 0 m = m :=
max_eq_right (zero_le _)
lemma one_le_of_lt {n m : ℕ} (h : n < m) : 1 ≤ m :=
lt_of_le_of_lt (nat.zero_le _) h
theorem eq_one_of_mul_eq_one_right {m n : ℕ} (H : m * n = 1) : m = 1 :=
eq_one_of_dvd_one ⟨n, H.symm⟩
theorem eq_one_of_mul_eq_one_left {m n : ℕ} (H : m * n = 1) : n = 1 :=
eq_one_of_mul_eq_one_right (by rwa mul_comm)
/-! ### `succ` -/
theorem eq_of_lt_succ_of_not_lt {a b : ℕ} (h1 : a < b + 1) (h2 : ¬ a < b) : a = b :=
have h3 : a ≤ b, from le_of_lt_succ h1,
or.elim (eq_or_lt_of_not_lt h2) (λ h, h) (λ h, absurd h (not_lt_of_ge h3))
lemma eq_of_le_of_lt_succ {n m : ℕ} (h₁ : n ≤ m) (h₂ : m < n + 1) : m = n :=
nat.le_antisymm (le_of_succ_le_succ h₂) h₁
theorem one_add (n : ℕ) : 1 + n = succ n := by simp [add_comm]
@[simp] lemma succ_pos' {n : ℕ} : 0 < succ n := succ_pos n
theorem succ_inj' {n m : ℕ} : succ n = succ m ↔ n = m :=
⟨succ.inj, congr_arg _⟩
theorem succ_injective : function.injective nat.succ := λ x y, succ.inj
lemma succ_ne_succ {n m : ℕ} : succ n ≠ succ m ↔ n ≠ m :=
succ_injective.ne_iff
@[simp] lemma succ_succ_ne_one (n : ℕ) : n.succ.succ ≠ 1 :=
succ_ne_succ.mpr n.succ_ne_zero
@[simp] lemma one_lt_succ_succ (n : ℕ) : 1 < n.succ.succ :=
succ_lt_succ $ succ_pos n
theorem succ_le_succ_iff {m n : ℕ} : succ m ≤ succ n ↔ m ≤ n :=
⟨le_of_succ_le_succ, succ_le_succ⟩
theorem max_succ_succ {m n : ℕ} :
max (succ m) (succ n) = succ (max m n) :=
begin
by_cases h1 : m ≤ n,
rw [max_eq_right h1, max_eq_right (succ_le_succ h1)],
{ rw not_le at h1, have h2 := le_of_lt h1,
rw [max_eq_left h2, max_eq_left (succ_le_succ h2)] }
end
lemma not_succ_lt_self {n : ℕ} : ¬succ n < n :=
not_lt_of_ge (nat.le_succ _)
theorem lt_succ_iff {m n : ℕ} : m < succ n ↔ m ≤ n :=
succ_le_succ_iff
lemma succ_le_iff {m n : ℕ} : succ m ≤ n ↔ m < n :=
⟨lt_of_succ_le, succ_le_of_lt⟩
lemma lt_iff_add_one_le {m n : ℕ} : m < n ↔ m + 1 ≤ n :=
by rw succ_le_iff
-- Just a restatement of `nat.lt_succ_iff` using `+1`.
lemma lt_add_one_iff {a b : ℕ} : a < b + 1 ↔ a ≤ b :=
lt_succ_iff
-- A flipped version of `lt_add_one_iff`.
lemma lt_one_add_iff {a b : ℕ} : a < 1 + b ↔ a ≤ b :=
by simp only [add_comm, lt_succ_iff]
-- This is true reflexively, by the definition of `≤` on ℕ,
-- but it's still useful to have, to convince Lean to change the syntactic type.
lemma add_one_le_iff {a b : ℕ} : a + 1 ≤ b ↔ a < b :=
iff.refl _
lemma one_add_le_iff {a b : ℕ} : 1 + a ≤ b ↔ a < b :=
by simp only [add_comm, add_one_le_iff]
theorem of_le_succ {n m : ℕ} (H : n ≤ m.succ) : n ≤ m ∨ n = m.succ :=
(lt_or_eq_of_le H).imp le_of_lt_succ id
lemma succ_lt_succ_iff {m n : ℕ} : succ m < succ n ↔ m < n :=
⟨lt_of_succ_lt_succ, succ_lt_succ⟩
lemma div_le_iff_le_mul_add_pred {m n k : ℕ} (n0 : 0 < n) : m / n ≤ k ↔ m ≤ n * k + (n - 1) :=
begin
rw [← lt_succ_iff, div_lt_iff_lt_mul _ _ n0, succ_mul, mul_comm],
cases n, {cases n0},
exact lt_succ_iff,
end
/-! ### `add` -/
-- Sometimes a bare `nat.add` or similar appears as a consequence of unfolding
-- during pattern matching. These lemmas package them back up as typeclass
-- mediated operations.
@[simp] theorem add_def {a b : ℕ} : nat.add a b = a + b := rfl
@[simp] theorem mul_def {a b : ℕ} : nat.mul a b = a * b := rfl
attribute [simp] nat.add_sub_cancel nat.add_sub_cancel_left
attribute [simp] nat.sub_self
lemma exists_eq_add_of_le : ∀ {m n : ℕ}, m ≤ n → ∃ k : ℕ, n = m + k
| 0 0 h := ⟨0, by simp⟩
| 0 (n+1) h := ⟨n+1, by simp⟩
| (m+1) (n+1) h :=
let ⟨k, hk⟩ := exists_eq_add_of_le (nat.le_of_succ_le_succ h) in
⟨k, by simp [hk, add_comm, add_left_comm]⟩
lemma exists_eq_add_of_lt : ∀ {m n : ℕ}, m < n → ∃ k : ℕ, n = m + k + 1
| 0 0 h := false.elim $ lt_irrefl _ h
| 0 (n+1) h := ⟨n, by simp⟩
| (m+1) (n+1) h := let ⟨k, hk⟩ := exists_eq_add_of_le (nat.le_of_succ_le_succ h) in
⟨k, by simp [hk]⟩
theorem add_pos_left {m : ℕ} (h : 0 < m) (n : ℕ) : 0 < m + n :=
calc
m + n > 0 + n : nat.add_lt_add_right h n
... = n : nat.zero_add n
... ≥ 0 : zero_le n
theorem add_pos_right (m : ℕ) {n : ℕ} (h : 0 < n) : 0 < m + n :=
begin rw add_comm, exact add_pos_left h m end
theorem add_pos_iff_pos_or_pos (m n : ℕ) : 0 < m + n ↔ 0 < m ∨ 0 < n :=
iff.intro
begin
intro h,
cases m with m,
{simp [zero_add] at h, exact or.inr h},
exact or.inl (succ_pos _)
end
begin
intro h, cases h with mpos npos,
{ apply add_pos_left mpos },
apply add_pos_right _ npos
end
lemma add_eq_one_iff : ∀ {a b : ℕ}, a + b = 1 ↔ (a = 0 ∧ b = 1) ∨ (a = 1 ∧ b = 0)
| 0 0 := dec_trivial
| 0 1 := dec_trivial
| 1 0 := dec_trivial
| 1 1 := dec_trivial
| (a+2) _ := by rw add_right_comm; exact dec_trivial
| _ (b+2) := by rw [← add_assoc]; simp only [nat.succ_inj', nat.succ_ne_zero]; simp
theorem le_add_one_iff {i j : ℕ} : i ≤ j + 1 ↔ (i ≤ j ∨ i = j + 1) :=
⟨assume h,
match nat.eq_or_lt_of_le h with
| or.inl h := or.inr h
| or.inr h := or.inl $ nat.le_of_succ_le_succ h
end,
or.rec (assume h, le_trans h $ nat.le_add_right _ _) le_of_eq⟩
lemma add_succ_lt_add {a b c d : ℕ} (hab : a < b) (hcd : c < d) : a + c + 1 < b + d :=
begin
rw add_assoc,
exact add_lt_add_of_lt_of_le hab (nat.succ_le_iff.2 hcd)
end
-- TODO: generalize to some ordered add_monoids, based on #6145
lemma le_of_add_le_left {a b c : ℕ} (h : a + b ≤ c) : a ≤ c :=
by { refine le_trans _ h, simp }
lemma le_of_add_le_right {a b c : ℕ} (h : a + b ≤ c) : b ≤ c :=
by { refine le_trans _ h, simp }
/-! ### `pred` -/
@[simp]
lemma add_succ_sub_one (n m : ℕ) : (n + succ m) - 1 = n + m :=
by rw [add_succ, succ_sub_one]
@[simp]
lemma succ_add_sub_one (n m : ℕ) : (succ n + m) - 1 = n + m :=
by rw [succ_add, succ_sub_one]
lemma pred_eq_sub_one (n : ℕ) : pred n = n - 1 := rfl
theorem pred_eq_of_eq_succ {m n : ℕ} (H : m = n.succ) : m.pred = n := by simp [H]
@[simp] lemma pred_eq_succ_iff {n m : ℕ} : pred n = succ m ↔ n = m + 2 :=
by cases n; split; rintro ⟨⟩; refl
theorem pred_sub (n m : ℕ) : pred n - m = pred (n - m) :=
by rw [← sub_one, nat.sub_sub, one_add]; refl
lemma le_pred_of_lt {n m : ℕ} (h : m < n) : m ≤ n - 1 :=
nat.sub_le_sub_right h 1
lemma le_of_pred_lt {m n : ℕ} : pred m < n → m ≤ n :=
match m with
| 0 := le_of_lt
| m+1 := id
end
/-- This ensures that `simp` succeeds on `pred (n + 1) = n`. -/
@[simp] lemma pred_one_add (n : ℕ) : pred (1 + n) = n :=
by rw [add_comm, add_one, pred_succ]
/-! ### `sub` -/
protected theorem le_sub_add (n m : ℕ) : n ≤ n - m + m :=
or.elim (le_total n m)
(assume : n ≤ m, begin rw [sub_eq_zero_of_le this, zero_add], exact this end)
(assume : m ≤ n, begin rw (nat.sub_add_cancel this) end)
theorem sub_add_eq_max (n m : ℕ) : n - m + m = max n m :=
eq_max (nat.le_sub_add _ _) (le_add_left _ _) $ λ k h₁ h₂,
by rw ← nat.sub_add_cancel h₂; exact
add_le_add_right (nat.sub_le_sub_right h₁ _) _
theorem add_sub_eq_max (n m : ℕ) : n + (m - n) = max n m :=
by rw [add_comm, max_comm, sub_add_eq_max]
theorem sub_add_min (n m : ℕ) : n - m + min n m = n :=
(le_total n m).elim
(λ h, by rw [min_eq_left h, sub_eq_zero_of_le h, zero_add])
(λ h, by rw [min_eq_right h, nat.sub_add_cancel h])
protected theorem add_sub_cancel' {n m : ℕ} (h : m ≤ n) : m + (n - m) = n :=
by rw [add_comm, nat.sub_add_cancel h]
protected theorem sub_add_sub_cancel {a b c : ℕ} (hab : b ≤ a) (hbc : c ≤ b) :
(a - b) + (b - c) = a - c :=
by rw [←nat.add_sub_assoc hbc, ←nat.sub_add_comm hab, nat.add_sub_cancel]
protected theorem sub_eq_of_eq_add (h : k = m + n) : k - m = n :=
begin rw [h, nat.add_sub_cancel_left] end
theorem sub_cancel {a b c : ℕ} (h₁ : a ≤ b) (h₂ : a ≤ c) (w : b - a = c - a) : b = c :=
by rw [←nat.sub_add_cancel h₁, ←nat.sub_add_cancel h₂, w]
lemma sub_sub_sub_cancel_right {a b c : ℕ} (h₂ : c ≤ b) : (a - c) - (b - c) = a - b :=
by rw [nat.sub_sub, ←nat.add_sub_assoc h₂, nat.add_sub_cancel_left]
lemma add_sub_cancel_right (n m k : ℕ) : n + (m + k) - k = n + m :=
by { rw [nat.add_sub_assoc, nat.add_sub_cancel], apply k.le_add_left }
protected lemma sub_add_eq_add_sub {a b c : ℕ} (h : b ≤ a) : (a - b) + c = (a + c) - b :=
by rw [add_comm a, nat.add_sub_assoc h, add_comm]
theorem sub_min (n m : ℕ) : n - min n m = n - m :=
nat.sub_eq_of_eq_add $ by rw [add_comm, sub_add_min]
theorem sub_sub_assoc {a b c : ℕ} (h₁ : b ≤ a) (h₂ : c ≤ b) : a - (b - c) = a - b + c :=
(nat.sub_eq_iff_eq_add (le_trans (nat.sub_le _ _) h₁)).2 $
by rw [add_right_comm, add_assoc, nat.sub_add_cancel h₂, nat.sub_add_cancel h₁]
protected theorem lt_of_sub_pos (h : 0 < n - m) : m < n :=
lt_of_not_ge
(assume : n ≤ m,
have n - m = 0, from sub_eq_zero_of_le this,
begin rw this at h, exact lt_irrefl _ h end)
protected theorem lt_of_sub_lt_sub_right : m - k < n - k → m < n :=
lt_imp_lt_of_le_imp_le (λ h, nat.sub_le_sub_right h _)
protected theorem lt_of_sub_lt_sub_left : m - n < m - k → k < n :=
lt_imp_lt_of_le_imp_le (nat.sub_le_sub_left _)
protected theorem sub_lt_self (h₁ : 0 < m) (h₂ : 0 < n) : m - n < m :=
calc
m - n = succ (pred m) - succ (pred n) : by rw [succ_pred_eq_of_pos h₁, succ_pred_eq_of_pos h₂]
... = pred m - pred n : by rw succ_sub_succ
... ≤ pred m : sub_le _ _
... < succ (pred m) : lt_succ_self _
... = m : succ_pred_eq_of_pos h₁
protected theorem le_sub_right_of_add_le (h : m + k ≤ n) : m ≤ n - k :=
by rw ← nat.add_sub_cancel m k; exact nat.sub_le_sub_right h k
protected theorem le_sub_left_of_add_le (h : k + m ≤ n) : m ≤ n - k :=
nat.le_sub_right_of_add_le (by rwa add_comm at h)
protected theorem lt_sub_right_of_add_lt (h : m + k < n) : m < n - k :=
lt_of_succ_le $ nat.le_sub_right_of_add_le $
by rw succ_add; exact succ_le_of_lt h
protected theorem lt_sub_left_of_add_lt (h : k + m < n) : m < n - k :=
nat.lt_sub_right_of_add_lt (by rwa add_comm at h)
protected theorem add_lt_of_lt_sub_right (h : m < n - k) : m + k < n :=
@nat.lt_of_sub_lt_sub_right _ _ k (by rwa nat.add_sub_cancel)
protected theorem add_lt_of_lt_sub_left (h : m < n - k) : k + m < n :=
by rw add_comm; exact nat.add_lt_of_lt_sub_right h
protected theorem le_add_of_sub_le_right : n - k ≤ m → n ≤ m + k :=
le_imp_le_of_lt_imp_lt nat.lt_sub_right_of_add_lt
protected theorem le_add_of_sub_le_left : n - k ≤ m → n ≤ k + m :=
le_imp_le_of_lt_imp_lt nat.lt_sub_left_of_add_lt
protected theorem lt_add_of_sub_lt_right : n - k < m → n < m + k :=
lt_imp_lt_of_le_imp_le nat.le_sub_right_of_add_le
protected theorem lt_add_of_sub_lt_left : n - k < m → n < k + m :=
lt_imp_lt_of_le_imp_le nat.le_sub_left_of_add_le
protected theorem sub_le_left_of_le_add : n ≤ k + m → n - k ≤ m :=
le_imp_le_of_lt_imp_lt nat.add_lt_of_lt_sub_left
protected theorem sub_le_right_of_le_add : n ≤ m + k → n - k ≤ m :=
le_imp_le_of_lt_imp_lt nat.add_lt_of_lt_sub_right
protected theorem sub_lt_left_iff_lt_add (H : n ≤ k) : k - n < m ↔ k < n + m :=
⟨nat.lt_add_of_sub_lt_left,
λ h₁,
have succ k ≤ n + m, from succ_le_of_lt h₁,
have succ (k - n) ≤ m, from
calc succ (k - n) = succ k - n : by rw (succ_sub H)
... ≤ n + m - n : nat.sub_le_sub_right this n
... = m : by rw nat.add_sub_cancel_left,
lt_of_succ_le this⟩
protected theorem le_sub_left_iff_add_le (H : m ≤ k) : n ≤ k - m ↔ m + n ≤ k :=
le_iff_le_iff_lt_iff_lt.2 (nat.sub_lt_left_iff_lt_add H)
protected theorem le_sub_right_iff_add_le (H : n ≤ k) : m ≤ k - n ↔ m + n ≤ k :=
by rw [nat.le_sub_left_iff_add_le H, add_comm]
protected theorem lt_sub_left_iff_add_lt : n < k - m ↔ m + n < k :=
⟨nat.add_lt_of_lt_sub_left, nat.lt_sub_left_of_add_lt⟩
protected theorem lt_sub_right_iff_add_lt : m < k - n ↔ m + n < k :=
by rw [nat.lt_sub_left_iff_add_lt, add_comm]
theorem sub_le_left_iff_le_add : m - n ≤ k ↔ m ≤ n + k :=
le_iff_le_iff_lt_iff_lt.2 nat.lt_sub_left_iff_add_lt
theorem sub_le_right_iff_le_add : m - k ≤ n ↔ m ≤ n + k :=
by rw [nat.sub_le_left_iff_le_add, add_comm]
protected theorem sub_lt_right_iff_lt_add (H : k ≤ m) : m - k < n ↔ m < n + k :=
by rw [nat.sub_lt_left_iff_lt_add H, add_comm]
protected theorem sub_le_sub_left_iff (H : k ≤ m) : m - n ≤ m - k ↔ k ≤ n :=
⟨λ h,
have k + (m - k) - n ≤ m - k, by rwa nat.add_sub_cancel' H,
nat.le_of_add_le_add_right (nat.le_add_of_sub_le_left this),
nat.sub_le_sub_left _⟩
protected theorem sub_lt_sub_right_iff (H : k ≤ m) : m - k < n - k ↔ m < n :=
lt_iff_lt_of_le_iff_le (nat.sub_le_sub_right_iff _ _ _ H)
protected theorem sub_lt_sub_left_iff (H : n ≤ m) : m - n < m - k ↔ k < n :=
lt_iff_lt_of_le_iff_le (nat.sub_le_sub_left_iff H)
protected theorem sub_le_iff : m - n ≤ k ↔ m - k ≤ n :=
nat.sub_le_left_iff_le_add.trans nat.sub_le_right_iff_le_add.symm
protected lemma sub_le_self (n m : ℕ) : n - m ≤ n :=
nat.sub_le_left_of_le_add (nat.le_add_left _ _)
protected theorem sub_lt_iff (h₁ : n ≤ m) (h₂ : k ≤ m) : m - n < k ↔ m - k < n :=
(nat.sub_lt_left_iff_lt_add h₁).trans (nat.sub_lt_right_iff_lt_add h₂).symm
lemma pred_le_iff {n m : ℕ} : pred n ≤ m ↔ n ≤ succ m :=
@nat.sub_le_right_iff_le_add n m 1
lemma lt_pred_iff {n m : ℕ} : n < pred m ↔ succ n < m :=
@nat.lt_sub_right_iff_add_lt n 1 m
lemma lt_of_lt_pred {a b : ℕ} (h : a < b - 1) : a < b :=
lt_of_succ_lt (lt_pred_iff.1 h)
/-! ### `mul` -/
lemma succ_mul_pos (m : ℕ) (hn : 0 < n) : 0 < (succ m) * n :=
mul_pos (succ_pos m) hn
theorem mul_self_le_mul_self {n m : ℕ} (h : n ≤ m) : n * n ≤ m * m :=
mul_le_mul h h (zero_le _) (zero_le _)
theorem mul_self_lt_mul_self : Π {n m : ℕ}, n < m → n * n < m * m
| 0 m h := mul_pos h h
| (succ n) m h := mul_lt_mul h (le_of_lt h) (succ_pos _) (zero_le _)
theorem mul_self_le_mul_self_iff {n m : ℕ} : n ≤ m ↔ n * n ≤ m * m :=
⟨mul_self_le_mul_self, λh, decidable.by_contradiction $
λhn, not_lt_of_ge h $ mul_self_lt_mul_self $ lt_of_not_ge hn⟩
theorem mul_self_lt_mul_self_iff {n m : ℕ} : n < m ↔ n * n < m * m :=
iff.trans (lt_iff_not_ge _ _) $ iff.trans (not_iff_not_of_iff mul_self_le_mul_self_iff) $
iff.symm (lt_iff_not_ge _ _)
theorem le_mul_self : Π (n : ℕ), n ≤ n * n
| 0 := le_refl _
| (n+1) := let t := mul_le_mul_left (n+1) (succ_pos n) in by simp at t; exact t
lemma le_mul_of_pos_left {m n : ℕ} (h : 0 < n) : m ≤ n * m :=
begin
conv {to_lhs, rw [← one_mul(m)]},
exact mul_le_mul_of_nonneg_right (nat.succ_le_of_lt h) dec_trivial,
end
lemma le_mul_of_pos_right {m n : ℕ} (h : 0 < n) : m ≤ m * n :=
begin
conv {to_lhs, rw [← mul_one(m)]},
exact mul_le_mul_of_nonneg_left (nat.succ_le_of_lt h) dec_trivial,
end
theorem two_mul_ne_two_mul_add_one {n m} : 2 * n ≠ 2 * m + 1 :=
mt (congr_arg (%2)) (by { rw [add_comm, add_mul_mod_self_left, mul_mod_right, mod_eq_of_lt]; simp })
lemma mul_eq_one_iff : ∀ {a b : ℕ}, a * b = 1 ↔ a = 1 ∧ b = 1
| 0 0 := dec_trivial
| 0 1 := dec_trivial
| 1 0 := dec_trivial
| (a+2) 0 := by simp
| 0 (b+2) := by simp
| (a+1) (b+1) := ⟨λ h, by simp only [add_mul, mul_add, mul_add, one_mul, mul_one,
(add_assoc _ _ _).symm, nat.succ_inj', add_eq_zero_iff] at h; simp [h.1.2, h.2],
by clear_aux_decl; finish⟩
protected theorem mul_left_inj {a b c : ℕ} (ha : 0 < a) : b * a = c * a ↔ b = c :=
⟨nat.eq_of_mul_eq_mul_right ha, λ e, e ▸ rfl⟩
protected theorem mul_right_inj {a b c : ℕ} (ha : 0 < a) : a * b = a * c ↔ b = c :=
⟨nat.eq_of_mul_eq_mul_left ha, λ e, e ▸ rfl⟩
lemma mul_left_injective {a : ℕ} (ha : 0 < a) : function.injective (λ x, x * a) :=
λ _ _, eq_of_mul_eq_mul_right ha
lemma mul_right_injective {a : ℕ} (ha : 0 < a) : function.injective (λ x, a * x) :=
λ _ _, eq_of_mul_eq_mul_left ha
lemma mul_ne_mul_left {a b c : ℕ} (ha : 0 < a) : b * a ≠ c * a ↔ b ≠ c :=
(mul_left_injective ha).ne_iff
lemma mul_ne_mul_right {a b c : ℕ} (ha : 0 < a) : a * b ≠ a * c ↔ b ≠ c :=
(mul_right_injective ha).ne_iff
lemma mul_right_eq_self_iff {a b : ℕ} (ha : 0 < a) : a * b = a ↔ b = 1 :=
suffices a * b = a * 1 ↔ b = 1, by rwa mul_one at this,
nat.mul_right_inj ha
lemma mul_left_eq_self_iff {a b : ℕ} (hb : 0 < b) : a * b = b ↔ a = 1 :=
by rw [mul_comm, nat.mul_right_eq_self_iff hb]
lemma lt_succ_iff_lt_or_eq {n i : ℕ} : n < i.succ ↔ (n < i ∨ n = i) :=
lt_succ_iff.trans le_iff_lt_or_eq
theorem mul_self_inj {n m : ℕ} : n * n = m * m ↔ n = m :=
le_antisymm_iff.trans (le_antisymm_iff.trans
(and_congr mul_self_le_mul_self_iff mul_self_le_mul_self_iff)).symm
/-!
### Recursion and induction principles
This section is here due to dependencies -- the lemmas here require some of the lemmas
proved above, and some of the results in later sections depend on the definitions in this section.
-/
@[simp] lemma rec_zero {C : ℕ → Sort u} (h0 : C 0) (h : ∀ n, C n → C (n + 1)) :
(nat.rec h0 h : Π n, C n) 0 = h0 :=
rfl
@[simp] lemma rec_add_one {C : ℕ → Sort u} (h0 : C 0) (h : ∀ n, C n → C (n + 1)) (n : ℕ) :
(nat.rec h0 h : Π n, C n) (n + 1) = h n ((nat.rec h0 h : Π n, C n) n) :=
rfl
/-- Recursion starting at a non-zero number: given a map `C k → C (k+1)` for each `k`,
there is a map from `C n` to each `C m`, `n ≤ m`. -/
@[elab_as_eliminator]
def le_rec_on {C : ℕ → Sort u} {n : ℕ} : Π {m : ℕ}, n ≤ m → (Π {k}, C k → C (k+1)) → C n → C m
| 0 H next x := eq.rec_on (eq_zero_of_le_zero H) x
| (m+1) H next x := or.by_cases (of_le_succ H) (λ h : n ≤ m, next $ le_rec_on h @next x)
(λ h : n = m + 1, eq.rec_on h x)
theorem le_rec_on_self {C : ℕ → Sort u} {n} {h : n ≤ n} {next} (x : C n) :
(le_rec_on h next x : C n) = x :=
by cases n; unfold le_rec_on or.by_cases; rw [dif_neg n.not_succ_le_self, dif_pos rfl]
theorem le_rec_on_succ {C : ℕ → Sort u} {n m} (h1 : n ≤ m) {h2 : n ≤ m+1} {next} (x : C n) :
(le_rec_on h2 @next x : C (m+1)) = next (le_rec_on h1 @next x : C m) :=
by conv { to_lhs, rw [le_rec_on, or.by_cases, dif_pos h1] }
theorem le_rec_on_succ' {C : ℕ → Sort u} {n} {h : n ≤ n+1} {next} (x : C n) :
(le_rec_on h next x : C (n+1)) = next x :=
by rw [le_rec_on_succ (le_refl n), le_rec_on_self]
theorem le_rec_on_trans {C : ℕ → Sort u} {n m k} (hnm : n ≤ m) (hmk : m ≤ k) {next} (x : C n) :
(le_rec_on (le_trans hnm hmk) @next x : C k) = le_rec_on hmk @next (le_rec_on hnm @next x) :=
begin
induction hmk with k hmk ih, { rw le_rec_on_self },
rw [le_rec_on_succ (le_trans hnm hmk), ih, le_rec_on_succ]
end
theorem le_rec_on_succ_left {C : ℕ → Sort u} {n m} (h1 : n ≤ m) (h2 : n+1 ≤ m)
{next : Π{{k}}, C k → C (k+1)} (x : C n) :
(le_rec_on h2 next (next x) : C m) = (le_rec_on h1 next x : C m) :=
begin
rw [subsingleton.elim h1 (le_trans (le_succ n) h2),
le_rec_on_trans (le_succ n) h2, le_rec_on_succ']
end
theorem le_rec_on_injective {C : ℕ → Sort u} {n m} (hnm : n ≤ m)
(next : Π n, C n → C (n+1)) (Hnext : ∀ n, function.injective (next n)) :
function.injective (le_rec_on hnm next) :=
begin
induction hnm with m hnm ih, { intros x y H, rwa [le_rec_on_self, le_rec_on_self] at H },
intros x y H, rw [le_rec_on_succ hnm, le_rec_on_succ hnm] at H, exact ih (Hnext _ H)
end
theorem le_rec_on_surjective {C : ℕ → Sort u} {n m} (hnm : n ≤ m)
(next : Π n, C n → C (n+1)) (Hnext : ∀ n, function.surjective (next n)) :
function.surjective (le_rec_on hnm next) :=
begin
induction hnm with m hnm ih, { intros x, use x, rw le_rec_on_self },
intros x, rcases Hnext _ x with ⟨w, rfl⟩, rcases ih w with ⟨x, rfl⟩, use x, rw le_rec_on_succ
end
/-- Recursion principle based on `<`. -/
@[elab_as_eliminator]
protected def strong_rec' {p : ℕ → Sort u} (H : ∀ n, (∀ m, m < n → p m) → p n) : ∀ (n : ℕ), p n
| n := H n (λ m hm, strong_rec' m)
/-- Recursion principle based on `<` applied to some natural number. -/
@[elab_as_eliminator]
def strong_rec_on' {P : ℕ → Sort*} (n : ℕ) (h : ∀ n, (∀ m, m < n → P m) → P n) : P n :=
nat.strong_rec' h n
theorem strong_rec_on_beta' {P : ℕ → Sort*} {h} {n : ℕ} :
(strong_rec_on' n h : P n) = h n (λ m hmn, (strong_rec_on' m h : P m)) :=
by { simp only [strong_rec_on'], rw nat.strong_rec' }
/-- Induction principle starting at a non-zero number. For maps to a `Sort*` see `le_rec_on`. -/
@[elab_as_eliminator] lemma le_induction {P : nat → Prop} {m}
(h0 : P m) (h1 : ∀ n, m ≤ n → P n → P (n + 1)) :
∀ n, m ≤ n → P n :=
by apply nat.less_than_or_equal.rec h0; exact h1
/-- Decreasing induction: if `P (k+1)` implies `P k`, then `P n` implies `P m` for all `m ≤ n`.
Also works for functions to `Sort*`. -/
@[elab_as_eliminator]
def decreasing_induction {P : ℕ → Sort*} (h : ∀n, P (n+1) → P n) {m n : ℕ} (mn : m ≤ n)
(hP : P n) : P m :=
le_rec_on mn (λ k ih hsk, ih $ h k hsk) (λ h, h) hP
@[simp] lemma decreasing_induction_self {P : ℕ → Sort*} (h : ∀n, P (n+1) → P n) {n : ℕ}
(nn : n ≤ n) (hP : P n) : (decreasing_induction h nn hP : P n) = hP :=
by { dunfold decreasing_induction, rw [le_rec_on_self] }
lemma decreasing_induction_succ {P : ℕ → Sort*} (h : ∀n, P (n+1) → P n) {m n : ℕ} (mn : m ≤ n)
(msn : m ≤ n + 1) (hP : P (n+1)) :
(decreasing_induction h msn hP : P m) = decreasing_induction h mn (h n hP) :=
by { dunfold decreasing_induction, rw [le_rec_on_succ] }
@[simp] lemma decreasing_induction_succ' {P : ℕ → Sort*} (h : ∀n, P (n+1) → P n) {m : ℕ}
(msm : m ≤ m + 1) (hP : P (m+1)) : (decreasing_induction h msm hP : P m) = h m hP :=
by { dunfold decreasing_induction, rw [le_rec_on_succ'] }
lemma decreasing_induction_trans {P : ℕ → Sort*} (h : ∀n, P (n+1) → P n) {m n k : ℕ}
(mn : m ≤ n) (nk : n ≤ k) (hP : P k) :
(decreasing_induction h (le_trans mn nk) hP : P m) =
decreasing_induction h mn (decreasing_induction h nk hP) :=
by { induction nk with k nk ih, rw [decreasing_induction_self],
rw [decreasing_induction_succ h (le_trans mn nk), ih, decreasing_induction_succ] }
lemma decreasing_induction_succ_left {P : ℕ → Sort*} (h : ∀n, P (n+1) → P n) {m n : ℕ}
(smn : m + 1 ≤ n) (mn : m ≤ n) (hP : P n) :
(decreasing_induction h mn hP : P m) = h m (decreasing_induction h smn hP) :=
by { rw [subsingleton.elim mn (le_trans (le_succ m) smn), decreasing_induction_trans,
decreasing_induction_succ'] }
/-! ### `div` -/
attribute [simp] nat.div_self
protected lemma div_le_of_le_mul' {m n : ℕ} {k} (h : m ≤ k * n) : m / k ≤ n :=
(eq_zero_or_pos k).elim
(λ k0, by rw [k0, nat.div_zero]; apply zero_le)
(λ k0, (decidable.mul_le_mul_left k0).1 $
calc k * (m / k)
≤ m % k + k * (m / k) : le_add_left _ _
... = m : mod_add_div _ _
... ≤ k * n : h)
protected lemma div_le_self' (m n : ℕ) : m / n ≤ m :=
(eq_zero_or_pos n).elim
(λ n0, by rw [n0, nat.div_zero]; apply zero_le)
(λ n0, nat.div_le_of_le_mul' $ calc
m = 1 * m : (one_mul _).symm
... ≤ n * m : mul_le_mul_right _ n0)
/-- A version of `nat.div_lt_self` using successors, rather than additional hypotheses. -/
lemma div_lt_self' (n b : ℕ) : (n+1)/(b+2) < n+1 :=
nat.div_lt_self (nat.succ_pos n) (nat.succ_lt_succ (nat.succ_pos _))
theorem le_div_iff_mul_le' {x y : ℕ} {k : ℕ} (k0 : 0 < k) : x ≤ y / k ↔ x * k ≤ y :=
le_div_iff_mul_le x y k0
theorem div_lt_iff_lt_mul' {x y : ℕ} {k : ℕ} (k0 : 0 < k) : x / k < y ↔ x < y * k :=
lt_iff_lt_of_le_iff_le $ le_div_iff_mul_le' k0
protected theorem div_le_div_right {n m : ℕ} (h : n ≤ m) {k : ℕ} : n / k ≤ m / k :=
(nat.eq_zero_or_pos k).elim (λ k0, by simp [k0]) $ λ hk,
(le_div_iff_mul_le' hk).2 $ le_trans (nat.div_mul_le_self _ _) h
lemma lt_of_div_lt_div {m n k : ℕ} (h : m / k < n / k) : m < n :=
by_contradiction $ λ h₁, absurd h (not_lt_of_ge (nat.div_le_div_right (not_lt.1 h₁)))
protected lemma div_pos {a b : ℕ} (hba : b ≤ a) (hb : 0 < b) : 0 < a / b :=
nat.pos_of_ne_zero (λ h, lt_irrefl a
(calc a = a % b : by simpa [h] using (mod_add_div a b).symm
... < b : nat.mod_lt a hb
... ≤ a : hba))
protected lemma div_lt_of_lt_mul {m n k : ℕ} (h : m < n * k) : m / n < k :=
lt_of_mul_lt_mul_left
(calc n * (m / n) ≤ m % n + n * (m / n) : nat.le_add_left _ _
... = m : mod_add_div _ _
... < n * k : h)
(nat.zero_le n)
lemma lt_mul_of_div_lt {a b c : ℕ} (h : a / c < b) (w : 0 < c) : a < b * c :=
lt_of_not_ge $ not_le_of_gt h ∘ (nat.le_div_iff_mul_le _ _ w).2
protected lemma div_eq_zero_iff {a b : ℕ} (hb : 0 < b) : a / b = 0 ↔ a < b :=
⟨λ h, by rw [← mod_add_div a b, h, mul_zero, add_zero]; exact mod_lt _ hb,
λ h, by rw [← nat.mul_right_inj hb, ← @add_left_cancel_iff _ _ (a % b), mod_add_div,
mod_eq_of_lt h, mul_zero, add_zero]⟩
protected lemma div_eq_zero {a b : ℕ} (hb : a < b) : a / b = 0 :=
(nat.div_eq_zero_iff $ (zero_le a).trans_lt hb).mpr hb
lemma eq_zero_of_le_div {a b : ℕ} (hb : 2 ≤ b) (h : a ≤ a / b) : a = 0 :=
eq_zero_of_mul_le hb $
by rw mul_comm; exact (nat.le_div_iff_mul_le' (lt_of_lt_of_le dec_trivial hb)).1 h
lemma mul_div_le_mul_div_assoc (a b c : ℕ) : a * (b / c) ≤ (a * b) / c :=
if hc0 : c = 0 then by simp [hc0]
else (nat.le_div_iff_mul_le _ _ (nat.pos_of_ne_zero hc0)).2
(by rw [mul_assoc]; exact mul_le_mul_left _ (nat.div_mul_le_self _ _))
lemma div_mul_div_le_div (a b c : ℕ) : ((a / c) * b) / a ≤ b / c :=
if ha0 : a = 0 then by simp [ha0]
else calc a / c * b / a ≤ b * a / c / a :
nat.div_le_div_right (by rw [mul_comm];
exact mul_div_le_mul_div_assoc _ _ _)
... = b / c : by rw [nat.div_div_eq_div_mul, mul_comm b, mul_comm c,
nat.mul_div_mul _ _ (nat.pos_of_ne_zero ha0)]
lemma eq_zero_of_le_half {a : ℕ} (h : a ≤ a / 2) : a = 0 :=
eq_zero_of_le_div (le_refl _) h
protected theorem eq_mul_of_div_eq_right {a b c : ℕ} (H1 : b ∣ a) (H2 : a / b = c) :
a = b * c :=
by rw [← H2, nat.mul_div_cancel' H1]
protected theorem div_eq_iff_eq_mul_right {a b c : ℕ} (H : 0 < b) (H' : b ∣ a) :
a / b = c ↔ a = b * c :=
⟨nat.eq_mul_of_div_eq_right H', nat.div_eq_of_eq_mul_right H⟩
protected theorem div_eq_iff_eq_mul_left {a b c : ℕ} (H : 0 < b) (H' : b ∣ a) :
a / b = c ↔ a = c * b :=
by rw mul_comm; exact nat.div_eq_iff_eq_mul_right H H'
protected theorem eq_mul_of_div_eq_left {a b c : ℕ} (H1 : b ∣ a) (H2 : a / b = c) :
a = c * b :=
by rw [mul_comm, nat.eq_mul_of_div_eq_right H1 H2]
protected theorem mul_div_cancel_left' {a b : ℕ} (Hd : a ∣ b) : a * (b / a) = b :=
by rw [mul_comm,nat.div_mul_cancel Hd]
/-! ### `mod`, `dvd` -/
lemma div_add_mod (m k : ℕ) : k * (m / k) + m % k = m :=
(nat.add_comm _ _).trans (mod_add_div _ _)
lemma mod_add_div' (m k : ℕ) : m % k + (m / k) * k = m :=
by { rw mul_comm, exact mod_add_div _ _ }
lemma div_add_mod' (m k : ℕ) : (m / k) * k + m % k = m :=
by { rw mul_comm, exact div_add_mod _ _ }
protected theorem div_mod_unique {n k m d : ℕ} (h : 0 < k) :
n / k = d ∧ n % k = m ↔ m + k * d = n ∧ m < k :=
⟨λ ⟨e₁, e₂⟩, e₁ ▸ e₂ ▸ ⟨mod_add_div _ _, mod_lt _ h⟩,
λ ⟨h₁, h₂⟩, h₁ ▸ by rw [add_mul_div_left _ _ h, add_mul_mod_self_left];
simp [div_eq_of_lt, mod_eq_of_lt, h₂]⟩
lemma two_mul_odd_div_two {n : ℕ} (hn : n % 2 = 1) : 2 * (n / 2) = n - 1 :=
by conv {to_rhs, rw [← nat.mod_add_div n 2, hn, nat.add_sub_cancel_left]}
lemma div_dvd_of_dvd {a b : ℕ} (h : b ∣ a) : (a / b) ∣ a :=
⟨b, (nat.div_mul_cancel h).symm⟩
protected lemma div_div_self : ∀ {a b : ℕ}, b ∣ a → 0 < a → a / (a / b) = b
| a 0 h₁ h₂ := by rw [eq_zero_of_zero_dvd h₁, nat.div_zero, nat.div_zero]
| 0 b h₁ h₂ := absurd h₂ dec_trivial
| (a+1) (b+1) h₁ h₂ :=
(nat.mul_left_inj (nat.div_pos (le_of_dvd (succ_pos a) h₁) (succ_pos b))).1 $
by rw [nat.div_mul_cancel (div_dvd_of_dvd h₁), nat.mul_div_cancel' h₁]
lemma mod_mul_right_div_self (a b c : ℕ) : a % (b * c) / b = (a / b) % c :=
begin
rcases (zero_le b).eq_or_lt with rfl|hb, { simp },
rcases (zero_le c).eq_or_lt with rfl|hc, { simp },
conv_rhs { rw ← mod_add_div a (b * c) },
rw [mul_assoc, nat.add_mul_div_left _ _ hb, add_mul_mod_self_left,
mod_eq_of_lt (nat.div_lt_of_lt_mul (mod_lt _ (mul_pos hb hc)))]
end
lemma mod_mul_left_div_self (a b c : ℕ) : a % (c * b) / b = (a / b) % c :=
by rw [mul_comm c, mod_mul_right_div_self]
@[simp] protected theorem dvd_one {n : ℕ} : n ∣ 1 ↔ n = 1 :=
⟨eq_one_of_dvd_one, λ e, e.symm ▸ dvd_refl _⟩
protected theorem dvd_add_left {k m n : ℕ} (h : k ∣ n) : k ∣ m + n ↔ k ∣ m :=
(nat.dvd_add_iff_left h).symm
protected theorem dvd_add_right {k m n : ℕ} (h : k ∣ m) : k ∣ m + n ↔ k ∣ n :=
(nat.dvd_add_iff_right h).symm
@[simp] protected theorem not_two_dvd_bit1 (n : ℕ) : ¬ 2 ∣ bit1 n :=
by { rw [bit1, nat.dvd_add_right two_dvd_bit0, nat.dvd_one], cc }
/-- A natural number `m` divides the sum `m + n` if and only if `m` divides `n`.-/
@[simp] protected lemma dvd_add_self_left {m n : ℕ} :
m ∣ m + n ↔ m ∣ n :=
nat.dvd_add_right (dvd_refl m)
/-- A natural number `m` divides the sum `n + m` if and only if `m` divides `n`.-/
@[simp] protected lemma dvd_add_self_right {m n : ℕ} :
m ∣ n + m ↔ m ∣ n :=
nat.dvd_add_left (dvd_refl m)
-- TODO: update `nat.dvd_sub` in core
lemma dvd_sub' {k m n : ℕ} (h₁ : k ∣ m) (h₂ : k ∣ n) : k ∣ m - n :=
begin
cases le_total n m with H H,
{ exact dvd_sub H h₁ h₂ },
{ rw nat.sub_eq_zero_of_le H,
exact dvd_zero k },
end
lemma not_dvd_of_pos_of_lt {a b : ℕ} (h1 : 0 < b) (h2 : b < a) : ¬ a ∣ b :=
begin
rintros ⟨c, rfl⟩,
rcases eq_zero_or_pos c with (rfl | hc),
{ exact lt_irrefl 0 h1 },
{ exact not_lt.2 (le_mul_of_pos_right hc) h2 },
end
protected theorem mul_dvd_mul_iff_left {a b c : ℕ} (ha : 0 < a) : a * b ∣ a * c ↔ b ∣ c :=
exists_congr $ λ d, by rw [mul_assoc, nat.mul_right_inj ha]
protected theorem mul_dvd_mul_iff_right {a b c : ℕ} (hc : 0 < c) : a * c ∣ b * c ↔ a ∣ b :=
exists_congr $ λ d, by rw [mul_right_comm, nat.mul_left_inj hc]
lemma succ_div : ∀ (a b : ℕ), (a + 1) / b =
a / b + if b ∣ a + 1 then 1 else 0
| a 0 := by simp
| 0 1 := by simp
| 0 (b+2) := have hb2 : b + 2 > 1, from dec_trivial,
by simp [ne_of_gt hb2, div_eq_of_lt hb2]
| (a+1) (b+1) := begin
rw [nat.div_def], conv_rhs { rw nat.div_def },
by_cases hb_eq_a : b = a + 1,
{ simp [hb_eq_a, le_refl] },
by_cases hb_le_a1 : b ≤ a + 1,
{ have hb_le_a : b ≤ a, from le_of_lt_succ (lt_of_le_of_ne hb_le_a1 hb_eq_a),
have h₁ : (0 < b + 1 ∧ b + 1 ≤ a + 1 + 1),
from ⟨succ_pos _, (add_le_add_iff_right _).2 hb_le_a1⟩,
have h₂ : (0 < b + 1 ∧ b + 1 ≤ a + 1),
from ⟨succ_pos _, (add_le_add_iff_right _).2 hb_le_a⟩,
have dvd_iff : b + 1 ∣ a - b + 1 ↔ b + 1 ∣ a + 1 + 1,
{ rw [nat.dvd_add_iff_left (dvd_refl (b + 1)),
← nat.add_sub_add_right a 1 b, add_comm (_ - _), add_assoc,
nat.sub_add_cancel (succ_le_succ hb_le_a), add_comm 1] },
have wf : a - b < a + 1, from lt_succ_of_le (nat.sub_le_self _ _),
rw [if_pos h₁, if_pos h₂, nat.add_sub_add_right, nat.sub_add_comm hb_le_a,
by exact have _ := wf, succ_div (a - b),
nat.add_sub_add_right],
simp [dvd_iff, succ_eq_add_one, add_comm 1, add_assoc] },
{ have hba : ¬ b ≤ a,
from not_le_of_gt (lt_trans (lt_succ_self a) (lt_of_not_ge hb_le_a1)),
have hb_dvd_a : ¬ b + 1 ∣ a + 2,
from λ h, hb_le_a1 (le_of_succ_le_succ (le_of_dvd (succ_pos _) h)),
simp [hba, hb_le_a1, hb_dvd_a], }
end
lemma succ_div_of_dvd {a b : ℕ} (hba : b ∣ a + 1) :
(a + 1) / b = a / b + 1 :=
by rw [succ_div, if_pos hba]
lemma succ_div_of_not_dvd {a b : ℕ} (hba : ¬ b ∣ a + 1) :
(a + 1) / b = a / b :=
by rw [succ_div, if_neg hba, add_zero]
@[simp] theorem mod_mod_of_dvd (n : nat) {m k : nat} (h : m ∣ k) : n % k % m = n % m :=
begin
conv { to_rhs, rw ←mod_add_div n k },
rcases h with ⟨t, rfl⟩, rw [mul_assoc, add_mul_mod_self_left]
end
@[simp] theorem mod_mod (a n : ℕ) : (a % n) % n = a % n :=
(eq_zero_or_pos n).elim
(λ n0, by simp [n0])
(λ npos, mod_eq_of_lt (mod_lt _ npos))
/-- If `a` and `b` are equal mod `c`, `a - b` is zero mod `c`. -/
lemma sub_mod_eq_zero_of_mod_eq {a b c : ℕ} (h : a % c = b % c) : (a - b) % c = 0 :=
by rw [←nat.mod_add_div a c, ←nat.mod_add_div b c, ←h, ←nat.sub_sub, nat.add_sub_cancel_left,
←nat.mul_sub_left_distrib, nat.mul_mod_right]
@[simp] lemma one_mod (n : ℕ) : 1 % (n + 2) = 1 := nat.mod_eq_of_lt (add_lt_add_right n.succ_pos 1)
lemma dvd_sub_mod (k : ℕ) : n ∣ (k - (k % n)) :=
⟨k / n, nat.sub_eq_of_eq_add (nat.mod_add_div k n).symm⟩
@[simp] theorem mod_add_mod (m n k : ℕ) : (m % n + k) % n = (m + k) % n :=
by have := (add_mul_mod_self_left (m % n + k) n (m / n)).symm;
rwa [add_right_comm, mod_add_div] at this
@[simp] theorem add_mod_mod (m n k : ℕ) : (m + n % k) % k = (m + n) % k :=
by rw [add_comm, mod_add_mod, add_comm]
lemma add_mod (a b n : ℕ) : (a + b) % n = ((a % n) + (b % n)) % n :=
by rw [add_mod_mod, mod_add_mod]
theorem add_mod_eq_add_mod_right {m n k : ℕ} (i : ℕ) (H : m % n = k % n) :
(m + i) % n = (k + i) % n :=
by rw [← mod_add_mod, ← mod_add_mod k, H]
theorem add_mod_eq_add_mod_left {m n k : ℕ} (i : ℕ) (H : m % n = k % n) :
(i + m) % n = (i + k) % n :=
by rw [add_comm, add_mod_eq_add_mod_right _ H, add_comm]
lemma mul_mod (a b n : ℕ) : (a * b) % n = ((a % n) * (b % n)) % n :=
begin
conv_lhs {
rw [←mod_add_div a n, ←mod_add_div' b n, right_distrib, left_distrib, left_distrib,
mul_assoc, mul_assoc, ←left_distrib n _ _, add_mul_mod_self_left, ← mul_assoc,
add_mul_mod_self_right] }
end
lemma dvd_div_of_mul_dvd {a b c : ℕ} (h : a * b ∣ c) : b ∣ c / a :=
if ha : a = 0 then
by simp [ha]
else
have ha : 0 < a, from nat.pos_of_ne_zero ha,
have h1 : ∃ d, c = a * b * d, from h,
let ⟨d, hd⟩ := h1 in
have h2 : c / a = b * d, from nat.div_eq_of_eq_mul_right ha (by simpa [mul_assoc] using hd),
show ∃ d, c / a = b * d, from ⟨d, h2⟩
lemma mul_dvd_of_dvd_div {a b c : ℕ} (hab : c ∣ b) (h : a ∣ b / c) : c * a ∣ b :=
have h1 : ∃ d, b / c = a * d, from h,
have h2 : ∃ e, b = c * e, from hab,
let ⟨d, hd⟩ := h1, ⟨e, he⟩ := h2 in
have h3 : b = a * d * c, from
nat.eq_mul_of_div_eq_left hab hd,
show ∃ d, b = c * a * d, from ⟨d, by cc⟩
lemma div_mul_div {a b c d : ℕ} (hab : b ∣ a) (hcd : d ∣ c) :
(a / b) * (c / d) = (a * c) / (b * d) :=
have exi1 : ∃ x, a = b * x, from hab,
have exi2 : ∃ y, c = d * y, from hcd,
if hb : b = 0 then by simp [hb]
else have 0 < b, from nat.pos_of_ne_zero hb,
if hd : d = 0 then by simp [hd]
else have 0 < d, from nat.pos_of_ne_zero hd,
begin
cases exi1 with x hx, cases exi2 with y hy,
rw [hx, hy, nat.mul_div_cancel_left, nat.mul_div_cancel_left],
symmetry,
apply nat.div_eq_of_eq_mul_left,
apply mul_pos,
repeat {assumption},
cc
end
@[simp]
lemma div_div_div_eq_div : ∀ {a b c : ℕ} (dvd : b ∣ a) (dvd2 : a ∣ c), (c / (a / b)) / b = c / a
| 0 _ := by simp
| (a + 1) 0 := λ _ dvd _, by simpa using dvd
| (a + 1) (c + 1) :=
have a_split : a + 1 ≠ 0 := succ_ne_zero a,
have c_split : c + 1 ≠ 0 := succ_ne_zero c,
λ b dvd dvd2,
begin
rcases dvd2 with ⟨k, rfl⟩,
rcases dvd with ⟨k2, pr⟩,
have k2_nonzero : k2 ≠ 0 := λ k2_zero, by simpa [k2_zero] using pr,
rw [nat.mul_div_cancel_left k (nat.pos_of_ne_zero a_split), pr,
nat.mul_div_cancel_left k2 (nat.pos_of_ne_zero c_split), nat.mul_comm ((c + 1) * k2) k,
←nat.mul_assoc k (c + 1) k2, nat.mul_div_cancel _ (nat.pos_of_ne_zero k2_nonzero),
nat.mul_div_cancel _ (nat.pos_of_ne_zero c_split)],
end
lemma eq_of_dvd_of_div_eq_one {a b : ℕ} (w : a ∣ b) (h : b / a = 1) : a = b :=
by rw [←nat.div_mul_cancel w, h, one_mul]
lemma eq_zero_of_dvd_of_div_eq_zero {a b : ℕ} (w : a ∣ b) (h : b / a = 0) : b = 0 :=
by rw [←nat.div_mul_cancel w, h, zero_mul]
/-- If a small natural number is divisible by a larger natural number,
the small number is zero. -/
lemma eq_zero_of_dvd_of_lt {a b : ℕ} (w : a ∣ b) (h : b < a) : b = 0 :=
nat.eq_zero_of_dvd_of_div_eq_zero w
((nat.div_eq_zero_iff (lt_of_le_of_lt (zero_le b) h)).elim_right h)
lemma div_le_div_left {a b c : ℕ} (h₁ : c ≤ b) (h₂ : 0 < c) : a / b ≤ a / c :=
(nat.le_div_iff_mul_le _ _ h₂).2 $
le_trans (mul_le_mul_left _ h₁) (div_mul_le_self _ _)
lemma div_eq_self {a b : ℕ} : a / b = a ↔ a = 0 ∨ b = 1 :=
begin
split,
{ intro,
cases b,
{ simp * at * },
{ cases b,
{ right, refl },
{ left,
have : a / (b + 2) ≤ a / 2 := div_le_div_left (by simp) dec_trivial,
refine eq_zero_of_le_half _,
simp * at * } } },
{ rintros (rfl|rfl); simp }
end
lemma lt_iff_le_pred : ∀ {m n : ℕ}, 0 < n → (m < n ↔ m ≤ n - 1)
| m (n+1) _ := lt_succ_iff
lemma div_eq_sub_mod_div {m n : ℕ} : m / n = (m - m % n) / n :=
begin
by_cases n0 : n = 0,
{ rw [n0, nat.div_zero, nat.div_zero] },
{ rw [← mod_add_div m n] { occs := occurrences.pos [2] },
rw [nat.add_sub_cancel_left, mul_div_right _ (nat.pos_of_ne_zero n0)] }
end
lemma mul_div_le (m n : ℕ) : n * (m / n) ≤ m :=
begin
cases nat.eq_zero_or_pos n with n0 h,
{ rw [n0, zero_mul], exact m.zero_le },
{ rw [mul_comm, ← nat.le_div_iff_mul_le' h] },
end
lemma lt_mul_div_succ (m : ℕ) {n : ℕ} (n0 : 0 < n) : m < n * ((m / n) + 1) :=
begin
rw [mul_comm, ← nat.div_lt_iff_lt_mul' n0],
exact lt_succ_self _
end
@[simp] lemma mod_div_self (m n : ℕ) : m % n / n = 0 :=
begin
cases n,
{ exact (m % 0).div_zero },
{ exact nat.div_eq_zero (m.mod_lt n.succ_pos) }
end
/-! ### `pow` -/
-- This is redundant with `canonically_ordered_semiring.pow_le_pow_of_le_left`,
-- but `canonically_ordered_semiring` is not such an obvious abstraction, and also quite long.
-- So, we leave a version in the `nat` namespace as well.
-- (The global `pow_le_pow_of_le_left` needs an extra hypothesis `0 ≤ x`.)
protected theorem pow_le_pow_of_le_left {x y : ℕ} (H : x ≤ y) : ∀ i : ℕ, x^i ≤ y^i :=
canonically_ordered_semiring.pow_le_pow_of_le_left H
theorem pow_le_pow_of_le_right {x : ℕ} (H : x > 0) {i : ℕ} : ∀ {j}, i ≤ j → x^i ≤ x^j
| 0 h := by rw eq_zero_of_le_zero h; apply le_refl
| (succ j) h := (lt_or_eq_of_le h).elim
(λhl, by rw [pow_succ', ← nat.mul_one (x^i)]; exact
nat.mul_le_mul (pow_le_pow_of_le_right $ le_of_lt_succ hl) H)
(λe, by rw e; refl)
theorem pow_lt_pow_of_lt_left {x y : ℕ} (H : x < y) {i} (h : 0 < i) : x^i < y^i :=
begin
cases i with i, { exact absurd h (not_lt_zero _) },
rw [pow_succ', pow_succ'],
exact nat.mul_lt_mul' (nat.pow_le_pow_of_le_left (le_of_lt H) _) H
(pow_pos (lt_of_le_of_lt (zero_le _) H) _)
end
theorem pow_lt_pow_of_lt_right {x : ℕ} (H : x > 1) {i j : ℕ} (h : i < j) : x^i < x^j :=
begin
have xpos := lt_of_succ_lt H,
refine lt_of_lt_of_le _ (pow_le_pow_of_le_right xpos h),
rw [← nat.mul_one (x^i), pow_succ'],
exact nat.mul_lt_mul_of_pos_left H (pow_pos xpos _)
end
-- TODO: Generalize?
lemma pow_lt_pow_succ {p : ℕ} (h : 1 < p) (n : ℕ) : p^n < p^(n+1) :=
suffices 1*p^n < p*p^n, by simpa [pow_succ],
nat.mul_lt_mul_of_pos_right h (pow_pos (lt_of_succ_lt h) n)
lemma lt_pow_self {p : ℕ} (h : 1 < p) : ∀ n : ℕ, n < p ^ n
| 0 := by simp [zero_lt_one]
| (n+1) := calc
n + 1 < p^n + 1 : nat.add_lt_add_right (lt_pow_self _) _
... ≤ p ^ (n+1) : pow_lt_pow_succ h _
lemma lt_two_pow (n : ℕ) : n < 2^n :=
lt_pow_self dec_trivial n
lemma one_le_pow (n m : ℕ) (h : 0 < m) : 1 ≤ m^n :=
by { rw ←one_pow n, exact nat.pow_le_pow_of_le_left h n }
lemma one_le_pow' (n m : ℕ) : 1 ≤ (m+1)^n := one_le_pow n (m+1) (succ_pos m)
lemma one_le_two_pow (n : ℕ) : 1 ≤ 2^n := one_le_pow n 2 dec_trivial
lemma one_lt_pow (n m : ℕ) (h₀ : 0 < n) (h₁ : 1 < m) : 1 < m^n :=
by { rw ←one_pow n, exact pow_lt_pow_of_lt_left h₁ h₀ }
lemma one_lt_pow' (n m : ℕ) : 1 < (m+2)^(n+1) :=
one_lt_pow (n+1) (m+2) (succ_pos n) (nat.lt_of_sub_eq_succ rfl)
lemma one_lt_two_pow (n : ℕ) (h₀ : 0 < n) : 1 < 2^n := one_lt_pow n 2 h₀ dec_trivial
lemma one_lt_two_pow' (n : ℕ) : 1 < 2^(n+1) := one_lt_pow (n+1) 2 (succ_pos n) dec_trivial
lemma pow_right_strict_mono {x : ℕ} (k : 2 ≤ x) : strict_mono (λ (n : ℕ), x^n) :=
λ _ _, pow_lt_pow_of_lt_right k
lemma pow_le_iff_le_right {x m n : ℕ} (k : 2 ≤ x) : x^m ≤ x^n ↔ m ≤ n :=
strict_mono.le_iff_le (pow_right_strict_mono k)
lemma pow_lt_iff_lt_right {x m n : ℕ} (k : 2 ≤ x) : x^m < x^n ↔ m < n :=
strict_mono.lt_iff_lt (pow_right_strict_mono k)
lemma pow_right_injective {x : ℕ} (k : 2 ≤ x) : function.injective (λ (n : ℕ), x^n) :=
strict_mono.injective (pow_right_strict_mono k)
lemma pow_left_strict_mono {m : ℕ} (k : 1 ≤ m) : strict_mono (λ (x : ℕ), x^m) :=
λ _ _ h, pow_lt_pow_of_lt_left h k
lemma mul_lt_mul_pow_succ {n a q : ℕ} (a0 : 0 < a) (q1 : 1 < q) :
n * q < a * q ^ (n + 1) :=
begin
rw [pow_succ', ← mul_assoc, mul_lt_mul_right (zero_lt_one.trans q1)],
exact lt_mul_of_one_le_of_lt' (nat.succ_le_iff.mpr a0) (nat.lt_pow_self q1 n),
end
end nat
lemma strict_mono.nat_pow {n : ℕ} (hn : 1 ≤ n) {f : ℕ → ℕ} (hf : strict_mono f) :
strict_mono (λ m, (f m) ^ n) :=
(nat.pow_left_strict_mono hn).comp hf
namespace nat
lemma pow_le_iff_le_left {m x y : ℕ} (k : 1 ≤ m) : x^m ≤ y^m ↔ x ≤ y :=
strict_mono.le_iff_le (pow_left_strict_mono k)
lemma pow_lt_iff_lt_left {m x y : ℕ} (k : 1 ≤ m) : x^m < y^m ↔ x < y :=
strict_mono.lt_iff_lt (pow_left_strict_mono k)
lemma pow_left_injective {m : ℕ} (k : 1 ≤ m) : function.injective (λ (x : ℕ), x^m) :=
strict_mono.injective (pow_left_strict_mono k)
theorem sq_sub_sq (a b : ℕ) : a ^ 2 - b ^ 2 = (a + b) * (a - b) :=
by { rw [sq, sq], exact nat.mul_self_sub_mul_self_eq a b }
alias nat.sq_sub_sq ← nat.pow_two_sub_pow_two
/-! ### `pow` and `mod` / `dvd` -/
theorem mod_pow_succ {b : ℕ} (b_pos : 0 < b) (w m : ℕ)
: m % (b^succ w) = b * (m/b % b^w) + m % b :=
begin
apply nat.strong_induction_on m,
clear m,
intros p IH,
cases lt_or_ge p (b^succ w) with h₁ h₁,
-- base case: p < b^succ w
{ have h₂ : p / b < b^w,
{ rw [div_lt_iff_lt_mul p _ b_pos],
simpa [pow_succ'] using h₁ },
rw [mod_eq_of_lt h₁, mod_eq_of_lt h₂],
simp [div_add_mod] },
-- step: p ≥ b^succ w
{ -- Generate condition for induction hypothesis
have h₂ : p - b^succ w < p,
{ apply sub_lt_of_pos_le _ _ (pow_pos b_pos _) h₁ },
-- Apply induction
rw [mod_eq_sub_mod h₁, IH _ h₂],
-- Normalize goal and h1
simp only [pow_succ],
simp only [ge, pow_succ] at h₁,
-- Pull subtraction outside mod and div
rw [sub_mul_mod _ _ _ h₁, sub_mul_div _ _ _ h₁],
-- Cancel subtraction inside mod b^w
have p_b_ge : b^w ≤ p / b,
{ rw [le_div_iff_mul_le _ _ b_pos, mul_comm],
exact h₁ },
rw [eq.symm (mod_eq_sub_mod p_b_ge)] }
end
lemma pow_dvd_pow_iff_pow_le_pow {k l : ℕ} : Π {x : ℕ} (w : 0 < x), x^k ∣ x^l ↔ x^k ≤ x^l
| (x+1) w :=
begin
split,
{ intro a, exact le_of_dvd (pow_pos (succ_pos x) l) a, },
{ intro a, cases x with x,
{ simp only [one_pow], },
{ have le := (pow_le_iff_le_right (le_add_left _ _)).mp a,
use (x+2)^(l-k),
rw [←pow_add, add_comm k, nat.sub_add_cancel le], } }
end
/-- If `1 < x`, then `x^k` divides `x^l` if and only if `k` is at most `l`. -/
lemma pow_dvd_pow_iff_le_right {x k l : ℕ} (w : 1 < x) : x^k ∣ x^l ↔ k ≤ l :=
by rw [pow_dvd_pow_iff_pow_le_pow (lt_of_succ_lt w), pow_le_iff_le_right w]
lemma pow_dvd_pow_iff_le_right' {b k l : ℕ} : (b+2)^k ∣ (b+2)^l ↔ k ≤ l :=
pow_dvd_pow_iff_le_right (nat.lt_of_sub_eq_succ rfl)
lemma not_pos_pow_dvd : ∀ {p k : ℕ} (hp : 1 < p) (hk : 1 < k), ¬ p^k ∣ p
| (succ p) (succ k) hp hk h :=
have succ p * (succ p)^k ∣ succ p * 1, by simpa [pow_succ] using h,
have (succ p) ^ k ∣ 1, from dvd_of_mul_dvd_mul_left (succ_pos _) this,
have he : (succ p) ^ k = 1, from eq_one_of_dvd_one this,
have k < (succ p) ^ k, from lt_pow_self hp k,
have k < 1, by rwa [he] at this,
have k = 0, from eq_zero_of_le_zero $ le_of_lt_succ this,
have 1 < 1, by rwa [this] at hk,
absurd this dec_trivial
lemma pow_dvd_of_le_of_pow_dvd {p m n k : ℕ} (hmn : m ≤ n) (hdiv : p ^ n ∣ k) : p ^ m ∣ k :=
have p ^ m ∣ p ^ n, from pow_dvd_pow _ hmn,
dvd_trans this hdiv
lemma dvd_of_pow_dvd {p k m : ℕ} (hk : 1 ≤ k) (hpk : p^k ∣ m) : p ∣ m :=
by rw ←pow_one p; exact pow_dvd_of_le_of_pow_dvd hk hpk
lemma pow_div {x m n : ℕ} (h : n ≤ m) (hx : 0 < x) : x ^ m / x ^ n = x ^ (m - n) :=
by rw [nat.div_eq_iff_eq_mul_left (pow_pos hx n) (pow_dvd_pow _ h), pow_sub_mul_pow _ h]
/-- `m` is not divisible by `n` iff it is between `n * k` and `n * (k + 1)` for some `k`. -/
lemma exists_lt_and_lt_iff_not_dvd (m : ℕ) {n : ℕ} (hn : 0 < n) :
(∃ k, n * k < m ∧ m < n * (k + 1)) ↔ ¬ n ∣ m :=
begin
split,
{ rintro ⟨k, h1k, h2k⟩ ⟨l, rfl⟩, rw [mul_lt_mul_left hn] at h1k h2k,
rw [lt_succ_iff, ← not_lt] at h2k, exact h2k h1k },
{ intro h, rw [dvd_iff_mod_eq_zero, ← ne.def, ← pos_iff_ne_zero] at h,
simp only [← mod_add_div m n] {single_pass := tt},
refine ⟨m / n, lt_add_of_pos_left _ h, _⟩,
rw [add_comm _ 1, left_distrib, mul_one], exact add_lt_add_right (mod_lt _ hn) _ }
end
/-- Two natural numbers are equal if and only if the have the same multiples. -/
lemma dvd_right_iff_eq {m n : ℕ} : (∀ a : ℕ, m ∣ a ↔ n ∣ a) ↔ m = n :=
⟨λ h, dvd_antisymm ((h _).mpr (dvd_refl _)) ((h _).mp (dvd_refl _)), λ h n, by rw h⟩
/-- Two natural numbers are equal if and only if the have the same divisors. -/
lemma dvd_left_iff_eq {m n : ℕ} : (∀ a : ℕ, a ∣ m ↔ a ∣ n) ↔ m = n :=
⟨λ h, dvd_antisymm ((h _).mp (dvd_refl _)) ((h _).mpr (dvd_refl _)), λ h n, by rw h⟩
/-- `dvd` is injective in the left argument -/
lemma dvd_left_injective : function.injective ((∣) : ℕ → ℕ → Prop) :=
λ m n h, dvd_right_iff_eq.mp $ λ a, iff_of_eq (congr_fun h a)
/-! ### `find` -/
section find
variables {p q : ℕ → Prop} [decidable_pred p] [decidable_pred q]
lemma find_eq_iff (h : ∃ n : ℕ, p n) : nat.find h = m ↔ p m ∧ ∀ n < m, ¬ p n :=
begin
split,
{ rintro rfl, exact ⟨nat.find_spec h, λ _, nat.find_min h⟩ },
{ rintro ⟨hm, hlt⟩,
exact le_antisymm (nat.find_min' h hm) (not_lt.1 $ imp_not_comm.1 (hlt _) $ nat.find_spec h) }
end
@[simp] lemma find_lt_iff (h : ∃ n : ℕ, p n) (n : ℕ) : nat.find h < n ↔ ∃ m < n, p m :=
⟨λ h2, ⟨nat.find h, h2, nat.find_spec h⟩, λ ⟨m, hmn, hm⟩, (nat.find_min' h hm).trans_lt hmn⟩
@[simp] lemma find_le_iff (h : ∃ n : ℕ, p n) (n : ℕ) : nat.find h ≤ n ↔ ∃ m ≤ n, p m :=
by simp only [exists_prop, ← lt_succ_iff, find_lt_iff]
@[simp] lemma le_find_iff (h : ∃ (n : ℕ), p n) (n : ℕ) : n ≤ nat.find h ↔ ∀ m < n, ¬ p m :=
by simp_rw [← not_lt, not_iff_comm, not_forall, not_not, find_lt_iff]
@[simp] lemma lt_find_iff (h : ∃ n : ℕ, p n) (n : ℕ) : n < nat.find h ↔ ∀ m ≤ n, ¬ p m :=
by simp only [← succ_le_iff, le_find_iff, succ_le_succ_iff]
@[simp] lemma find_eq_zero (h : ∃ n : ℕ, p n) : nat.find h = 0 ↔ p 0 :=
by simp [find_eq_iff]
@[simp] lemma find_pos (h : ∃ n : ℕ, p n) : 0 < nat.find h ↔ ¬ p 0 :=
by rw [pos_iff_ne_zero, not_iff_not, nat.find_eq_zero]
theorem find_le (h : ∀ n, q n → p n) (hp : ∃ n, p n) (hq : ∃ n, q n) :
nat.find hp ≤ nat.find hq :=
nat.find_min' _ (h _ (nat.find_spec hq))
lemma find_comp_succ (h₁ : ∃ n, p n) (h₂ : ∃ n, p (n + 1)) (h0 : ¬ p 0) :
nat.find h₁ = nat.find h₂ + 1 :=
begin
refine (find_eq_iff _).2 ⟨nat.find_spec h₂, λ n hn, _⟩,
cases n with n,
exacts [h0, @nat.find_min (λ n, p (n + 1)) _ h₂ _ (succ_lt_succ_iff.1 hn)]
end
end find
/-! ### `find_greatest` -/
section find_greatest
/-- `find_greatest P b` is the largest `i ≤ bound` such that `P i` holds, or `0` if no such `i`
exists -/
protected def find_greatest (P : ℕ → Prop) [decidable_pred P] : ℕ → ℕ
| 0 := 0
| (n + 1) := if P (n + 1) then n + 1 else find_greatest n
variables {P : ℕ → Prop} [decidable_pred P]
@[simp] lemma find_greatest_zero : nat.find_greatest P 0 = 0 := rfl
@[simp] lemma find_greatest_eq : ∀{b}, P b → nat.find_greatest P b = b
| 0 h := rfl
| (n + 1) h := by simp [nat.find_greatest, h]
@[simp] lemma find_greatest_of_not {b} (h : ¬ P (b + 1)) :
nat.find_greatest P (b + 1) = nat.find_greatest P b :=
by simp [nat.find_greatest, h]
lemma find_greatest_eq_iff {b m} :
nat.find_greatest P b = m ↔ m ≤ b ∧ (m ≠ 0 → P m) ∧ (∀ ⦃n⦄, m < n → n ≤ b → ¬P n) :=
begin
induction b with b ihb generalizing m,
{ rw [eq_comm, iff.comm],
simp only [nonpos_iff_eq_zero, ne.def, and_iff_left_iff_imp, find_greatest_zero],
rintro rfl,
exact ⟨λ h, (h rfl).elim, λ n hlt heq, (hlt.ne heq.symm).elim⟩ },
{ by_cases hb : P (b + 1),
{ rw [find_greatest_eq hb], split,
{ rintro rfl,
exact ⟨le_refl _, λ _, hb, λ n hlt hle, (hlt.not_le hle).elim⟩ },
{ rintros ⟨hle, h0, hm⟩,
rcases hle.eq_or_lt with rfl|hlt,
exacts [rfl, (hm hlt (le_refl _) hb).elim] } },
{ rw [find_greatest_of_not hb, ihb],
split,
{ rintros ⟨hle, hP, hm⟩,
refine ⟨hle.trans b.le_succ, hP, λ n hlt hle, _⟩,
rcases hle.eq_or_lt with rfl|hlt',
exacts [hb, hm hlt $ lt_succ_iff.1 hlt'] },
{ rintros ⟨hle, hP, hm⟩,
refine ⟨lt_succ_iff.1 (hle.lt_of_ne _), hP, λ n hlt hle, hm hlt (hle.trans b.le_succ)⟩,
rintro rfl,
exact hb (hP b.succ_ne_zero) } } }
end
lemma find_greatest_eq_zero_iff {b} :
nat.find_greatest P b = 0 ↔ ∀ ⦃n⦄, 0 < n → n ≤ b → ¬P n :=
by simp [find_greatest_eq_iff]
lemma find_greatest_spec {b} (h : ∃m, m ≤ b ∧ P m) : P (nat.find_greatest P b) :=
begin
rcases h with ⟨m, hmb, hm⟩,
by_cases h : nat.find_greatest P b = 0,
{ cases m, { rwa h },
exact ((find_greatest_eq_zero_iff.1 h) m.zero_lt_succ hmb hm).elim },
{ exact (find_greatest_eq_iff.1 rfl).2.1 h }
end
lemma find_greatest_le {b} : nat.find_greatest P b ≤ b :=
(find_greatest_eq_iff.1 rfl).1
lemma le_find_greatest {b m} (hmb : m ≤ b) (hm : P m) : m ≤ nat.find_greatest P b :=
le_of_not_lt $ λ hlt, (find_greatest_eq_iff.1 rfl).2.2 hlt hmb hm
lemma find_greatest_is_greatest {b k} (hk : nat.find_greatest P b < k) (hkb : k ≤ b) :
¬ P k :=
(find_greatest_eq_iff.1 rfl).2.2 hk hkb
lemma find_greatest_of_ne_zero {b m} (h : nat.find_greatest P b = m) (h0 : m ≠ 0) : P m :=
(find_greatest_eq_iff.1 h).2.1 h0
end find_greatest
/-! ### `bodd_div2` and `bodd` -/
@[simp] theorem bodd_div2_eq (n : ℕ) : bodd_div2 n = (bodd n, div2 n) :=
by unfold bodd div2; cases bodd_div2 n; refl
@[simp] lemma bodd_bit0 (n) : bodd (bit0 n) = ff := bodd_bit ff n
@[simp] lemma bodd_bit1 (n) : bodd (bit1 n) = tt := bodd_bit tt n
@[simp] lemma div2_bit0 (n) : div2 (bit0 n) = n := div2_bit ff n
@[simp] lemma div2_bit1 (n) : div2 (bit1 n) = n := div2_bit tt n
/-! ### `bit0` and `bit1` -/
-- There is no need to prove `bit0_eq_zero : bit0 n = 0 ↔ n = 0`
-- as this is true for any `[semiring R] [no_zero_divisors R] [char_zero R]`
-- However the lemmas `bit0_eq_bit0`, `bit1_eq_bit1`, `bit1_eq_one`, `one_eq_bit1`
-- need `[ring R] [no_zero_divisors R] [char_zero R]` in general,
-- so we prove `ℕ` specialized versions here.
@[simp] lemma bit0_eq_bit0 {m n : ℕ} : bit0 m = bit0 n ↔ m = n :=
⟨nat.bit0_inj, λ h, by subst h⟩
@[simp] lemma bit1_eq_bit1 {m n : ℕ} : bit1 m = bit1 n ↔ m = n :=
⟨nat.bit1_inj, λ h, by subst h⟩
@[simp] lemma bit1_eq_one {n : ℕ} : bit1 n = 1 ↔ n = 0 :=
⟨@nat.bit1_inj n 0, λ h, by subst h⟩
@[simp] lemma one_eq_bit1 {n : ℕ} : 1 = bit1 n ↔ n = 0 :=
⟨λ h, (@nat.bit1_inj 0 n h).symm, λ h, by subst h⟩
protected theorem bit0_le {n m : ℕ} (h : n ≤ m) : bit0 n ≤ bit0 m :=
add_le_add h h
protected theorem bit1_le {n m : ℕ} (h : n ≤ m) : bit1 n ≤ bit1 m :=
succ_le_succ (add_le_add h h)
theorem bit_le : ∀ (b : bool) {n m : ℕ}, n ≤ m → bit b n ≤ bit b m
| tt n m h := nat.bit1_le h
| ff n m h := nat.bit0_le h
theorem bit_ne_zero (b) {n} (h : n ≠ 0) : bit b n ≠ 0 :=
by cases b; [exact nat.bit0_ne_zero h, exact nat.bit1_ne_zero _]
theorem bit0_le_bit : ∀ (b) {m n : ℕ}, m ≤ n → bit0 m ≤ bit b n
| tt m n h := le_of_lt $ nat.bit0_lt_bit1 h
| ff m n h := nat.bit0_le h
theorem bit_le_bit1 : ∀ (b) {m n : ℕ}, m ≤ n → bit b m ≤ bit1 n
| ff m n h := le_of_lt $ nat.bit0_lt_bit1 h
| tt m n h := nat.bit1_le h
theorem bit_lt_bit0 : ∀ (b) {n m : ℕ}, n < m → bit b n < bit0 m
| tt n m h := nat.bit1_lt_bit0 h
| ff n m h := nat.bit0_lt h
theorem bit_lt_bit (a b) {n m : ℕ} (h : n < m) : bit a n < bit b m :=
lt_of_lt_of_le (bit_lt_bit0 _ h) (bit0_le_bit _ (le_refl _))
@[simp] lemma bit0_le_bit1_iff : bit0 k ≤ bit1 n ↔ k ≤ n :=
⟨λ h, by rwa [← nat.lt_succ_iff, n.bit1_eq_succ_bit0, ← n.bit0_succ_eq,
bit0_lt_bit0, nat.lt_succ_iff] at h, λ h, le_of_lt (nat.bit0_lt_bit1 h)⟩
@[simp] lemma bit0_lt_bit1_iff : bit0 k < bit1 n ↔ k ≤ n :=
⟨λ h, bit0_le_bit1_iff.1 (le_of_lt h), nat.bit0_lt_bit1⟩
@[simp] lemma bit1_le_bit0_iff : bit1 k ≤ bit0 n ↔ k < n :=
⟨λ h, by rwa [k.bit1_eq_succ_bit0, succ_le_iff, bit0_lt_bit0] at h,
λ h, le_of_lt (nat.bit1_lt_bit0 h)⟩
@[simp] lemma bit1_lt_bit0_iff : bit1 k < bit0 n ↔ k < n :=
⟨λ h, bit1_le_bit0_iff.1 (le_of_lt h), nat.bit1_lt_bit0⟩
@[simp] lemma one_le_bit0_iff : 1 ≤ bit0 n ↔ 0 < n :=
by { convert bit1_le_bit0_iff, refl, }
@[simp] lemma one_lt_bit0_iff : 1 < bit0 n ↔ 1 ≤ n :=
by { convert bit1_lt_bit0_iff, refl, }
@[simp] lemma bit_le_bit_iff : ∀ {b : bool}, bit b k ≤ bit b n ↔ k ≤ n
| ff := bit0_le_bit0
| tt := bit1_le_bit1
@[simp] lemma bit_lt_bit_iff : ∀ {b : bool}, bit b k < bit b n ↔ k < n
| ff := bit0_lt_bit0
| tt := bit1_lt_bit1
@[simp] lemma bit_le_bit1_iff : ∀ {b : bool}, bit b k ≤ bit1 n ↔ k ≤ n
| ff := bit0_le_bit1_iff
| tt := bit1_le_bit1
@[simp] lemma bit0_mod_two : bit0 n % 2 = 0 := by { rw nat.mod_two_of_bodd, simp }
@[simp] lemma bit1_mod_two : bit1 n % 2 = 1 := by { rw nat.mod_two_of_bodd, simp }
lemma pos_of_bit0_pos {n : ℕ} (h : 0 < bit0 n) : 0 < n :=
by { cases n, cases h, apply succ_pos, }
/-- Define a function on `ℕ` depending on parity of the argument. -/
@[elab_as_eliminator]
def bit_cases {C : ℕ → Sort u} (H : Π b n, C (bit b n)) (n : ℕ) : C n :=
eq.rec_on n.bit_decomp (H (bodd n) (div2 n))
/-! ### `shiftl` and `shiftr` -/
lemma shiftl_eq_mul_pow (m) : ∀ n, shiftl m n = m * 2 ^ n
| 0 := (nat.mul_one _).symm
| (k+1) := show bit0 (shiftl m k) = m * (2 * 2 ^ k),
by rw [bit0_val, shiftl_eq_mul_pow, mul_left_comm, mul_comm 2]
lemma shiftl'_tt_eq_mul_pow (m) : ∀ n, shiftl' tt m n + 1 = (m + 1) * 2 ^ n
| 0 := by simp [shiftl, shiftl', pow_zero, nat.one_mul]
| (k+1) :=
begin
change bit1 (shiftl' tt m k) + 1 = (m + 1) * (2 * 2 ^ k),
rw bit1_val,
change 2 * (shiftl' tt m k + 1) = _,
rw [shiftl'_tt_eq_mul_pow, mul_left_comm, mul_comm 2],
end
lemma one_shiftl (n) : shiftl 1 n = 2 ^ n :=
(shiftl_eq_mul_pow _ _).trans (nat.one_mul _)
@[simp] lemma zero_shiftl (n) : shiftl 0 n = 0 :=
(shiftl_eq_mul_pow _ _).trans (nat.zero_mul _)
lemma shiftr_eq_div_pow (m) : ∀ n, shiftr m n = m / 2 ^ n
| 0 := (nat.div_one _).symm
| (k+1) := (congr_arg div2 (shiftr_eq_div_pow k)).trans $
by rw [div2_val, nat.div_div_eq_div_mul, mul_comm]; refl
@[simp] lemma zero_shiftr (n) : shiftr 0 n = 0 :=
(shiftr_eq_div_pow _ _).trans (nat.zero_div _)
theorem shiftl'_ne_zero_left (b) {m} (h : m ≠ 0) (n) : shiftl' b m n ≠ 0 :=
by induction n; simp [shiftl', bit_ne_zero, *]
theorem shiftl'_tt_ne_zero (m) : ∀ {n} (h : n ≠ 0), shiftl' tt m n ≠ 0
| 0 h := absurd rfl h
| (succ n) _ := nat.bit1_ne_zero _
/-! ### `size` -/
@[simp] theorem size_zero : size 0 = 0 := by simp [size]
@[simp] theorem size_bit {b n} (h : bit b n ≠ 0) : size (bit b n) = succ (size n) :=
begin
rw size,
conv { to_lhs, rw [binary_rec], simp [h] },
rw div2_bit,
end
@[simp] theorem size_bit0 {n} (h : n ≠ 0) : size (bit0 n) = succ (size n) :=
@size_bit ff n (nat.bit0_ne_zero h)
@[simp] theorem size_bit1 (n) : size (bit1 n) = succ (size n) :=
@size_bit tt n (nat.bit1_ne_zero n)
@[simp] theorem size_one : size 1 = 1 :=
show size (bit1 0) = 1, by rw [size_bit1, size_zero]
@[simp] theorem size_shiftl' {b m n} (h : shiftl' b m n ≠ 0) :
size (shiftl' b m n) = size m + n :=
begin
induction n with n IH; simp [shiftl'] at h ⊢,
rw [size_bit h, nat.add_succ],
by_cases s0 : shiftl' b m n = 0; [skip, rw [IH s0]],
rw s0 at h ⊢,
cases b, {exact absurd rfl h},
have : shiftl' tt m n + 1 = 1 := congr_arg (+1) s0,
rw [shiftl'_tt_eq_mul_pow] at this,
have m0 := succ.inj (eq_one_of_dvd_one ⟨_, this.symm⟩),
subst m0,
simp at this,
have : n = 0 := eq_zero_of_le_zero (le_of_not_gt $ λ hn,
ne_of_gt (pow_lt_pow_of_lt_right dec_trivial hn) this),
subst n, refl
end
@[simp] theorem size_shiftl {m} (h : m ≠ 0) (n) :
size (shiftl m n) = size m + n :=
size_shiftl' (shiftl'_ne_zero_left _ h _)
theorem lt_size_self (n : ℕ) : n < 2^size n :=
begin
rw [← one_shiftl],
have : ∀ {n}, n = 0 → n < shiftl 1 (size n), { simp },
apply binary_rec _ _ n, {apply this rfl},
intros b n IH,
by_cases bit b n = 0, {apply this h},
rw [size_bit h, shiftl_succ],
exact bit_lt_bit0 _ IH
end
theorem size_le {m n : ℕ} : size m ≤ n ↔ m < 2^n :=
⟨λ h, lt_of_lt_of_le (lt_size_self _) (pow_le_pow_of_le_right dec_trivial h),
begin
rw [← one_shiftl], revert n,
apply binary_rec _ _ m,
{ intros n h, simp },
{ intros b m IH n h,
by_cases e : bit b m = 0, { simp [e] },
rw [size_bit e],
cases n with n,
{ exact e.elim (eq_zero_of_le_zero (le_of_lt_succ h)) },
{ apply succ_le_succ (IH _),
apply lt_imp_lt_of_le_imp_le (λ h', bit0_le_bit _ h') h } }
end⟩
theorem lt_size {m n : ℕ} : m < size n ↔ 2^m ≤ n :=
by rw [← not_lt, iff_not_comm, not_lt, size_le]
theorem size_pos {n : ℕ} : 0 < size n ↔ 0 < n :=
by rw lt_size; refl
theorem size_eq_zero {n : ℕ} : size n = 0 ↔ n = 0 :=
by have := @size_pos n; simp [pos_iff_ne_zero] at this;
exact not_iff_not.1 this
theorem size_pow {n : ℕ} : size (2^n) = n+1 :=
le_antisymm
(size_le.2 $ pow_lt_pow_of_lt_right dec_trivial (lt_succ_self _))
(lt_size.2 $ le_refl _)
theorem size_le_size {m n : ℕ} (h : m ≤ n) : size m ≤ size n :=
size_le.2 $ lt_of_le_of_lt h (lt_size_self _)
/-! ### decidability of predicates -/
instance decidable_ball_lt (n : nat) (P : Π k < n, Prop) :
∀ [H : ∀ n h, decidable (P n h)], decidable (∀ n h, P n h) :=
begin
induction n with n IH; intro; resetI,
{ exact is_true (λ n, dec_trivial) },
cases IH (λ k h, P k (lt_succ_of_lt h)) with h,
{ refine is_false (mt _ h), intros hn k h, apply hn },
by_cases p : P n (lt_succ_self n),
{ exact is_true (λ k h',
(lt_or_eq_of_le $ le_of_lt_succ h').elim (h _)
(λ e, match k, e, h' with _, rfl, h := p end)) },
{ exact is_false (mt (λ hn, hn _ _) p) }
end
instance decidable_forall_fin {n : ℕ} (P : fin n → Prop)
[H : decidable_pred P] : decidable (∀ i, P i) :=
decidable_of_iff (∀ k h, P ⟨k, h⟩) ⟨λ a ⟨k, h⟩, a k h, λ a k h, a ⟨k, h⟩⟩
instance decidable_ball_le (n : ℕ) (P : Π k ≤ n, Prop)
[H : ∀ n h, decidable (P n h)] : decidable (∀ n h, P n h) :=
decidable_of_iff (∀ k (h : k < succ n), P k (le_of_lt_succ h))
⟨λ a k h, a k (lt_succ_of_le h), λ a k h, a k _⟩
instance decidable_lo_hi (lo hi : ℕ) (P : ℕ → Prop) [H : decidable_pred P] :
decidable (∀x, lo ≤ x → x < hi → P x) :=
decidable_of_iff (∀ x < hi - lo, P (lo + x))
⟨λal x hl hh, by have := al (x - lo) (lt_of_not_ge $
(not_congr (nat.sub_le_sub_right_iff _ _ _ hl)).2 $ not_le_of_gt hh);
rwa [nat.add_sub_of_le hl] at this,
λal x h, al _ (nat.le_add_right _ _) (nat.add_lt_of_lt_sub_left h)⟩
instance decidable_lo_hi_le (lo hi : ℕ) (P : ℕ → Prop) [H : decidable_pred P] :
decidable (∀x, lo ≤ x → x ≤ hi → P x) :=
decidable_of_iff (∀x, lo ≤ x → x < hi + 1 → P x) $
ball_congr $ λ x hl, imp_congr lt_succ_iff iff.rfl
instance decidable_exists_lt {P : ℕ → Prop} [h : decidable_pred P] :
decidable_pred (λ n, ∃ (m : ℕ), m < n ∧ P m)
| 0 := is_false (by simp)
| (n + 1) := decidable_of_decidable_of_iff (@or.decidable _ _ (decidable_exists_lt n) (h n))
(by simp only [lt_succ_iff_lt_or_eq, or_and_distrib_right, exists_or_distrib, exists_eq_left])
end nat
|
092efec97ce37092fd3f03cec706831722620425 | a726f88081e44db9edfd14d32cfe9c4393ee56a4 | /src/mynat/le.lean | 3f248dc8637a455ad1dd31c9c898568481dab1af | [] | no_license | b-mehta/natural_number_game | 80451bf10277adc89a55dbe8581692c36d822462 | 9faf799d0ab48ecbc89b3d70babb65ba64beee3b | refs/heads/master | 1,598,525,389,186 | 1,573,516,674,000 | 1,573,516,674,000 | 217,339,684 | 0 | 0 | null | 1,571,933,100,000 | 1,571,933,099,000 | null | UTF-8 | Lean | false | false | 429 | lean | import mynat.mul
-- this is one of *three* routes to
-- canonically_ordered_comm_semiring
namespace mynat
def le (a b : mynat) := ∃ (c : mynat), b = a + c
-- Third choices:
-- | le 0 _
-- | le (succ a) (succ b) = le ab
-- notation
instance : has_le mynat := ⟨mynat.le⟩
@[leakage] theorem le_def' : mynat.le = (≤) := rfl
theorem le_def (a b : mynat) : a ≤ b ↔ ∃ (c : mynat), b = a + c := iff.rfl
end mynat |
40c2e99a5eb82fe67de421fe9a190383fbaab596 | ce6917c5bacabee346655160b74a307b4a5ab620 | /src/ch5/ex0511.lean | d3876afc2120e45e30c72721bc717bf09641f957 | [] | no_license | Ailrun/Theorem_Proving_in_Lean | ae6a23f3c54d62d401314d6a771e8ff8b4132db2 | 2eb1b5caf93c6a5a555c79e9097cf2ba5a66cf68 | refs/heads/master | 1,609,838,270,467 | 1,586,846,743,000 | 1,586,846,743,000 | 240,967,761 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 172 | lean | example (p q r : Prop) (hp : p) (hq : q) (hr : r) :
p ∧ ((p ∧ q) ∧ r) ∧ (q ∧ r ∧ p) :=
begin
repeat { any_goals { split } },
all_goals { assumption }
end
|
c68ae70ea6c5f6d1dd993345bb5ea2aa1b351c83 | e0f9ba56b7fedc16ef8697f6caeef5898b435143 | /src/data/complex/module.lean | ba155b49d48ac47aaa1194a0ac6f45a6b20404c3 | [
"Apache-2.0"
] | permissive | anrddh/mathlib | 6a374da53c7e3a35cb0298b0cd67824efef362b4 | a4266a01d2dcb10de19369307c986d038c7bb6a6 | refs/heads/master | 1,656,710,827,909 | 1,589,560,456,000 | 1,589,560,456,000 | 264,271,800 | 0 | 0 | Apache-2.0 | 1,589,568,062,000 | 1,589,568,061,000 | null | UTF-8 | Lean | false | false | 835 | lean | /-
Copyright (c) 2020 Alexander Bentkamp, Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Alexander Bentkamp, Sébastien Gouëzel
-/
import data.complex.basic ring_theory.algebra
/-!
This file contains two instance, the fact the ℂ is an ℝ algebra,
and an instance to view any complex vector space as a
real vector space
-/
noncomputable theory
namespace complex
instance algebra_over_reals : algebra ℝ ℂ := (ring_hom.of coe).to_algebra
end complex
/- Register as an instance (with low priority) the fact that a complex vector space is also a real
vector space. -/
instance module.complex_to_real (E : Type*) [add_comm_group E] [module ℂ E] : module ℝ E :=
module.restrict_scalars ℝ ℂ E
attribute [instance, priority 900] module.complex_to_real
|
1c06b8f84956c4cbc31eaaa07b1a165709bbcaec | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/1093.lean | 79c844e28684bc66e7f01bb7971c789f23d21497 | [
"Apache-2.0"
] | permissive | leanprover-community/lean | 12b87f69d92e614daea8bcc9d4de9a9ace089d0e | cce7990ea86a78bdb383e38ed7f9b5ba93c60ce0 | refs/heads/master | 1,687,508,156,644 | 1,684,951,104,000 | 1,684,951,104,000 | 169,960,991 | 457 | 107 | Apache-2.0 | 1,686,744,372,000 | 1,549,790,268,000 | C++ | UTF-8 | Lean | false | false | 156 | lean | open tactic nat
constant zadd (a : nat) : 0 + a = a
constant le.refl (a : nat) : a ≤ a
attribute [simp] zadd
example (a : nat) : 0 + a ≤ a :=
by simp
|
8cc1812356c59c4a7d4d5e239f2eb60c0c5c6284 | f57570f33b51ef0271f8c366142363d5ae8fff45 | /src/interior_algebra.lean | 486e939f5a678f420d16cfa468c769f602dcdc3e | [] | no_license | maxd13/lean-logic | 4083cb3fbb45b423befca7fda7268b8ba85ff3a6 | ddcab46b77adca91b120a5f37afbd48794da8b52 | refs/heads/master | 1,692,257,681,488 | 1,631,740,832,000 | 1,631,740,832,000 | 246,324,437 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 2,776 | lean | import data.set.lattice topology.basic order.bounded_lattice
open set lattice
set_option old_structure_cmd true
universe u
class has_operator (α : Type u) :=
(operator : α → α)
notation `#` := has_operator.operator
class order_retract (α : Type u) extends has_operator α, order_top α, order_bot α :=
(monotone : ∀ x y : α, x ≤ y → # x ≤ # y) -- Axiom K
(idempotent : ∀ x : α, (# ∘ #) x = # x) -- Axiom 4
class necessity (α : Type u) extends order_retract α :=
(decreasing : ∀ x : α, # x ≤ x) -- Axiom T
(top_open : # top = top) -- Necessitation rule
class possibility (α : Type u) extends order_retract α :=
(increasing : ∀ x : α, x ≤ # x)
(bot_closed : # bot = bot)
class interior_algebra (α : Type u) extends necessity α, boolean_algebra α
class closure_algebra (α : Type u) extends possibility α, boolean_algebra α
notation `□` := necessity.operator
notation `⋄` := possibility.operator
variable {α : Type u}
@[simp, reducible]
def pbot [c : closure_algebra α] : ⋄ ⊥ = (⊥:α) := c.bot_closed
lemma possibility_top_open [closure_algebra α] : -⋄(-⊤) = (⊤:α) :=
by simp --rw [neg_top, pbot, neg_bot]
instance classical_possibility [necessity α] [Ω : boolean_algebra α] : possibility α :=
{ operator := - (□ ∘ has_neg.neg),
monotone := sorry,
idempotent := sorry,
increasing := sorry,
bot_closed := sorry,
..Ω }
instance classical_necessity [possibility α] [Ω : boolean_algebra α] : necessity α :=
{ operator := - (⋄ ∘ has_neg.neg),
monotone := sorry,
idempotent := sorry,
decreasing := sorry,
top_open := sorry,
..Ω }
instance set_dualize₁ [necessity (set α)] : possibility (set α) := by apply_instance
instance set_dualize₂ [possibility (set α)] : necessity (set α) := by apply_instance
open topological_space
instance topological_interior [topological_space α ] : necessity (set α) :=
{
operator := interior,
monotone := @interior_mono α _ ,
idempotent := @interior_interior α _,
decreasing := @interior_subset α _,
top_open := @interior_univ α _,
..set.lattice_set }
instance topological_closure [topological_space α ] : possibility (set α) := by apply_instance
instance closure_from_possibility [p : possibility (set α)] : topological_space α :=
{ is_open := λ s, - ⋄(-s) = s,
is_open_univ := by {!!),--by rwa p.bot_closed,
is_open_inter := _,
is_open_sUnion := _ }
-- instance topological_closure [topological_space α ] : possibility (set α) :=
-- {
-- operator := closure,
-- monotone := @closure_mono α _ ,
-- idempotent := @closure_closure α _,
-- increasing := @subset_closure α _,
-- bot_closed := @closure_empty α _,
-- ..set.lattice_set }
|
5fa9a2dde688e1405cf7689f901f40a57f12c27f | b7f22e51856f4989b970961f794f1c435f9b8f78 | /tests/lean/run/tactic26.lean | 6bad0664a6a68dcba662397a13fc63348d5a93e6 | [
"Apache-2.0"
] | permissive | soonhokong/lean | cb8aa01055ffe2af0fb99a16b4cda8463b882cd1 | 38607e3eb57f57f77c0ac114ad169e9e4262e24f | refs/heads/master | 1,611,187,284,081 | 1,450,766,737,000 | 1,476,122,547,000 | 11,513,992 | 2 | 0 | null | 1,401,763,102,000 | 1,374,182,235,000 | C++ | UTF-8 | Lean | false | false | 872 | lean | import logic data.num
open tactic inhabited
namespace foo
inductive sum (A : Type) (B : Type) : Type :=
| inl : A → sum A B
| inr : B → sum A B
theorem inl_inhabited {A : Type} (B : Type) (H : inhabited A) : inhabited (sum A B)
:= inhabited.destruct H (λ a, inhabited.mk (sum.inl B a))
theorem inr_inhabited (A : Type) {B : Type} (H : inhabited B) : inhabited (sum A B)
:= inhabited.destruct H (λ b, inhabited.mk (sum.inr A b))
notation `(` h `|` r:(foldl `|` (e r, tactic.or_else r e) h) `)` := r
infixl `;`:15 := tactic.and_then
reveal inl_inhabited inr_inhabited
definition my_tac := fixpoint (λ t, ( apply @inl_inhabited; t
| apply @inr_inhabited; t
| apply @num.is_inhabited
))
tactic_hint my_tac
theorem T : inhabited (sum false num)
end foo
|
983da37a77316ae74db9884ab58c3e8f9e8b76c3 | f5f7e6fae601a5fe3cac7cc3ed353ed781d62419 | /src/data/list/perm.lean | c58c9cf009aa1e9b816387f030897109767476f2 | [
"Apache-2.0"
] | permissive | EdAyers/mathlib | 9ecfb2f14bd6caad748b64c9c131befbff0fb4e0 | ca5d4c1f16f9c451cf7170b10105d0051db79e1b | refs/heads/master | 1,626,189,395,845 | 1,555,284,396,000 | 1,555,284,396,000 | 144,004,030 | 0 | 0 | Apache-2.0 | 1,533,727,664,000 | 1,533,727,663,000 | null | UTF-8 | Lean | false | false | 41,051 | lean | /-
Copyright (c) 2015 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura, Jeremy Avigad, Mario Carneiro
List permutations.
-/
import data.list.basic
namespace list
universe variables uu vv
variables {α : Type uu} {β : Type vv}
/-- `perm l₁ l₂` or `l₁ ~ l₂` asserts that `l₁` and `l₂` are permutations
of each other. This is defined by induction using pairwise swaps. -/
inductive perm : list α → list α → Prop
| nil : perm [] []
| skip : Π (x : α) {l₁ l₂ : list α}, perm l₁ l₂ → perm (x::l₁) (x::l₂)
| swap : Π (x y : α) (l : list α), perm (y::x::l) (x::y::l)
| trans : Π {l₁ l₂ l₃ : list α}, perm l₁ l₂ → perm l₂ l₃ → perm l₁ l₃
open perm
infix ~ := perm
@[refl] protected theorem perm.refl : ∀ (l : list α), l ~ l
| [] := perm.nil
| (x::xs) := skip x (perm.refl xs)
@[symm] protected theorem perm.symm {l₁ l₂ : list α} (p : l₁ ~ l₂) : l₂ ~ l₁ :=
perm.rec_on p
perm.nil
(λ x l₁ l₂ p₁ r₁, skip x r₁)
(λ x y l, swap y x l)
(λ l₁ l₂ l₃ p₁ p₂ r₁ r₂, trans r₂ r₁)
theorem perm.swap'
(x y : α) {l₁ l₂ : list α} (p : l₁ ~ l₂) : y::x::l₁ ~ x::y::l₂ :=
trans (swap _ _ _) (skip _ $ skip _ p)
attribute [trans] perm.trans
theorem perm.eqv (α : Type) : equivalence (@perm α) :=
mk_equivalence (@perm α) (@perm.refl α) (@perm.symm α) (@perm.trans α)
instance is_setoid (α : Type) : setoid (list α) :=
setoid.mk (@perm α) (perm.eqv α)
theorem perm_subset {l₁ l₂ : list α} (p : l₁ ~ l₂) : l₁ ⊆ l₂ :=
λ a, perm.rec_on p
(λ h, h)
(λ x l₁ l₂ p₁ r₁ i, or.elim i
(λ ax, by simp [ax])
(λ al₁, or.inr (r₁ al₁)))
(λ x y l ayxl, or.elim ayxl
(λ ay, by simp [ay])
(λ axl, or.elim axl
(λ ax, by simp [ax])
(λ al, or.inr (or.inr al))))
(λ l₁ l₂ l₃ p₁ p₂ r₁ r₂ ainl₁, r₂ (r₁ ainl₁))
theorem mem_of_perm {a : α} {l₁ l₂ : list α} (h : l₁ ~ l₂) : a ∈ l₁ ↔ a ∈ l₂ :=
iff.intro (λ m, perm_subset h m) (λ m, perm_subset h.symm m)
theorem perm_app_left {l₁ l₂ : list α} (t₁ : list α) (p : l₁ ~ l₂) : l₁++t₁ ~ l₂++t₁ :=
perm.rec_on p
(perm.refl ([] ++ t₁))
(λ x l₁ l₂ p₁ r₁, skip x r₁)
(λ x y l, swap x y _)
(λ l₁ l₂ l₃ p₁ p₂ r₁ r₂, trans r₁ r₂)
theorem perm_app_right {t₁ t₂ : list α} : ∀ (l : list α), t₁ ~ t₂ → l++t₁ ~ l++t₂
| [] p := p
| (x::xs) p := skip x (perm_app_right xs p)
theorem perm_app {l₁ l₂ t₁ t₂ : list α} (p₁ : l₁ ~ l₂) (p₂ : t₁ ~ t₂) : l₁++t₁ ~ l₂++t₂ :=
trans (perm_app_left t₁ p₁) (perm_app_right l₂ p₂)
theorem perm_app_cons (a : α) {h₁ h₂ t₁ t₂ : list α}
(p₁ : h₁ ~ h₂) (p₂ : t₁ ~ t₂) : h₁ ++ a::t₁ ~ h₂ ++ a::t₂ :=
perm_app p₁ (skip a p₂)
@[simp] theorem perm_middle {a : α} : ∀ {l₁ l₂ : list α}, l₁++a::l₂ ~ a::(l₁++l₂)
| [] l₂ := perm.refl _
| (b::l₁) l₂ := (skip b (@perm_middle l₁ l₂)).trans (swap a b _)
@[simp] theorem perm_cons_app (a : α) (l : list α) : l ++ [a] ~ a::l :=
by simpa using @perm_middle _ a l []
@[simp] theorem perm_app_comm : ∀ {l₁ l₂ : list α}, (l₁++l₂) ~ (l₂++l₁)
| [] l₂ := by simp
| (a::t) l₂ := (skip a perm_app_comm).trans perm_middle.symm
theorem concat_perm (l : list α) (a : α) : concat l a ~ a :: l :=
by simp
theorem perm_length {l₁ l₂ : list α} (p : l₁ ~ l₂) : length l₁ = length l₂ :=
perm.rec_on p
rfl
(λ x l₁ l₂ p r, by simp[r])
(λ x y l, by simp)
(λ l₁ l₂ l₃ p₁ p₂ r₁ r₂, eq.trans r₁ r₂)
theorem eq_nil_of_perm_nil {l₁ : list α} (p : [] ~ l₁) : l₁ = [] :=
eq_nil_of_length_eq_zero (perm_length p).symm
theorem perm_nil {l₁ : list α} : l₁ ~ [] ↔ l₁ = [] :=
⟨λ p, eq_nil_of_perm_nil p.symm, λ e, e ▸ perm.refl _⟩
theorem not_perm_nil_cons (x : α) (l : list α) : ¬ [] ~ x::l
| p := by injection eq_nil_of_perm_nil p
theorem eq_singleton_of_perm {a b : α} (p : [a] ~ [b]) : a = b :=
by simpa using perm_subset p (by simp)
theorem eq_singleton_of_perm_inv {a : α} {l : list α} (p : [a] ~ l) : l = [a] :=
match l, show 1 = _, from perm_length p, p with
| [a'], rfl, p := by rw [eq_singleton_of_perm p]
end
@[simp] theorem reverse_perm : ∀ (l : list α), reverse l ~ l
| [] := perm.nil
| (a::l) := by rw reverse_cons; exact
(perm_cons_app _ _).trans (skip a $ reverse_perm l)
theorem perm_cons_app_cons {l l₁ l₂ : list α} (a : α) (p : l ~ l₁++l₂) : a::l ~ l₁++(a::l₂) :=
trans (skip a p) perm_middle.symm
@[simp] theorem perm_repeat {a : α} {n : ℕ} {l : list α} : repeat a n ~ l ↔ repeat a n = l :=
⟨λ p, (eq_repeat.2 $ by exact
⟨by simpa using (perm_length p).symm,
λ b m, eq_of_mem_repeat $ perm_subset p.symm m⟩).symm,
λ h, h ▸ perm.refl _⟩
theorem perm_erase [decidable_eq α] {a : α} {l : list α} (h : a ∈ l) : l ~ a :: l.erase a :=
let ⟨l₁, l₂, _, e₁, e₂⟩ := exists_erase_eq h in
e₂.symm ▸ e₁.symm ▸ perm_middle
@[elab_as_eliminator] theorem perm_induction_on
{P : list α → list α → Prop} {l₁ l₂ : list α} (p : l₁ ~ l₂)
(h₁ : P [] [])
(h₂ : ∀ x l₁ l₂, l₁ ~ l₂ → P l₁ l₂ → P (x::l₁) (x::l₂))
(h₃ : ∀ x y l₁ l₂, l₁ ~ l₂ → P l₁ l₂ → P (y::x::l₁) (x::y::l₂))
(h₄ : ∀ l₁ l₂ l₃, l₁ ~ l₂ → l₂ ~ l₃ → P l₁ l₂ → P l₂ l₃ → P l₁ l₃) :
P l₁ l₂ :=
have P_refl : ∀ l, P l l, from
assume l,
list.rec_on l h₁ (λ x xs ih, h₂ x xs xs (perm.refl xs) ih),
perm.rec_on p h₁ h₂ (λ x y l, h₃ x y l l (perm.refl l) (P_refl l)) h₄
@[congr] theorem perm_filter_map (f : α → option β) {l₁ l₂ : list α} (p : l₁ ~ l₂) :
filter_map f l₁ ~ filter_map f l₂ :=
begin
induction p with x l₂ l₂' p IH x y l₂ l₂ m₂ r₂ p₁ p₂ IH₁ IH₂,
{ simp },
{ simp [filter_map], cases f x with a; simp [filter_map, IH, skip] },
{ simp [filter_map], cases f x with a; cases f y with b; simp [filter_map, swap] },
{ exact IH₁.trans IH₂ }
end
@[congr] theorem perm_map (f : α → β) {l₁ l₂ : list α} (p : l₁ ~ l₂) :
map f l₁ ~ map f l₂ :=
by rw ← filter_map_eq_map; apply perm_filter_map _ p
theorem perm_pmap {p : α → Prop} (f : Π a, p a → β)
{l₁ l₂ : list α} (p : l₁ ~ l₂) {H₁ H₂} : pmap f l₁ H₁ ~ pmap f l₂ H₂ :=
begin
induction p with x l₂ l₂' p IH x y l₂ l₂ m₂ r₂ p₁ p₂ IH₁ IH₂,
{ simp },
{ simp [IH, skip] },
{ simp [swap] },
{ refine IH₁.trans IH₂,
exact λ a m, H₂ a (perm_subset p₂ m) }
end
theorem perm_filter (p : α → Prop) [decidable_pred p]
{l₁ l₂ : list α} (s : l₁ ~ l₂) : filter p l₁ ~ filter p l₂ :=
by rw ← filter_map_eq_filter; apply perm_filter_map _ s
theorem exists_perm_sublist {l₁ l₂ l₂' : list α}
(s : l₁ <+ l₂) (p : l₂ ~ l₂') : ∃ l₁' ~ l₁, l₁' <+ l₂' :=
begin
induction p with x l₂ l₂' p IH x y l₂ l₂ m₂ r₂ p₁ p₂ IH₁ IH₂ generalizing l₁ s,
{ exact ⟨[], eq_nil_of_sublist_nil s ▸ perm.refl _, nil_sublist _⟩ },
{ cases s with _ _ _ s l₁ _ _ s,
{ exact let ⟨l₁', p', s'⟩ := IH s in ⟨l₁', p', s'.cons _ _ _⟩ },
{ exact let ⟨l₁', p', s'⟩ := IH s in ⟨x::l₁', skip x p', s'.cons2 _ _ _⟩ } },
{ cases s with _ _ _ s l₁ _ _ s; cases s with _ _ _ s l₁ _ _ s,
{ exact ⟨l₁, perm.refl _, (s.cons _ _ _).cons _ _ _⟩ },
{ exact ⟨x::l₁, perm.refl _, (s.cons _ _ _).cons2 _ _ _⟩ },
{ exact ⟨y::l₁, perm.refl _, (s.cons2 _ _ _).cons _ _ _⟩ },
{ exact ⟨x::y::l₁, perm.swap _ _ _, (s.cons2 _ _ _).cons2 _ _ _⟩ } },
{ exact let ⟨m₁, pm, sm⟩ := IH₁ s, ⟨r₁, pr, sr⟩ := IH₂ sm in
⟨r₁, pr.trans pm, sr⟩ }
end
section rel
open relator
variables {γ : Type*} {δ : Type*} {r : α → β → Prop} {p : γ → δ → Prop}
local infixr ` ∘r ` : 80 := relation.comp
lemma perm_comp_perm : (perm ∘r perm : list α → list α → Prop) = perm :=
begin
funext a c, apply propext,
split,
{ exact assume ⟨b, hab, hba⟩, perm.trans hab hba },
{ exact assume h, ⟨a, perm.refl a, h⟩ }
end
lemma perm_comp_forall₂ {l u v} (hlu : perm l u) (huv : forall₂ r u v) : (forall₂ r ∘r perm) l v :=
begin
induction hlu generalizing v,
case perm.nil { cases huv, exact ⟨[], forall₂.nil, perm.nil⟩ },
case perm.skip : a l u hlu ih {
cases huv with _ b _ v hab huv',
rcases ih huv' with ⟨l₂, h₁₂, h₂₃⟩,
exact ⟨b::l₂, forall₂.cons hab h₁₂, perm.skip _ h₂₃⟩
},
case perm.swap : a₁ a₂ l₁ l₂ h₂₃ {
cases h₂₃ with _ b₁ _ l₂ h₁ hr_₂₃,
cases hr_₂₃ with _ b₂ _ l₂ h₂ h₁₂,
exact ⟨b₂::b₁::l₂, forall₂.cons h₂ (forall₂.cons h₁ h₁₂), perm.swap _ _ _⟩
},
case perm.trans : la₁ la₂ la₃ _ _ ih₁ ih₂ {
rcases ih₂ huv with ⟨lb₂, hab₂, h₂₃⟩,
rcases ih₁ hab₂ with ⟨lb₁, hab₁, h₁₂⟩,
exact ⟨lb₁, hab₁, perm.trans h₁₂ h₂₃⟩
}
end
lemma forall₂_comp_perm_eq_perm_comp_forall₂ : forall₂ r ∘r perm = perm ∘r forall₂ r :=
begin
funext l₁ l₃, apply propext,
split,
{ assume h, rcases h with ⟨l₂, h₁₂, h₂₃⟩,
have : forall₂ (flip r) l₂ l₁, from h₁₂.flip ,
rcases perm_comp_forall₂ h₂₃.symm this with ⟨l', h₁, h₂⟩,
exact ⟨l', h₂.symm, h₁.flip⟩ },
{ exact assume ⟨l₂, h₁₂, h₂₃⟩, perm_comp_forall₂ h₁₂ h₂₃ }
end
lemma rel_perm_imp (hr : right_unique r) : (forall₂ r ⇒ forall₂ r ⇒ implies) perm perm :=
assume a b h₁ c d h₂ h,
have (flip (forall₂ r) ∘r (perm ∘r forall₂ r)) b d, from ⟨a, h₁, c, h, h₂⟩,
have ((flip (forall₂ r) ∘r forall₂ r) ∘r perm) b d,
by rwa [← forall₂_comp_perm_eq_perm_comp_forall₂, ← relation.comp_assoc] at this,
let ⟨b', ⟨c', hbc, hcb⟩, hbd⟩ := this in
have b' = b, from right_unique_forall₂ @hr hcb hbc,
this ▸ hbd
lemma rel_perm (hr : bi_unique r) : (forall₂ r ⇒ forall₂ r ⇒ (↔)) perm perm :=
assume a b hab c d hcd, iff.intro
(rel_perm_imp hr.2 hab hcd)
(rel_perm_imp (assume a b c, left_unique_flip hr.1) hab.flip hcd.flip)
end rel
section subperm
/-- `subperm l₁ l₂`, denoted `l₁ <+~ l₂`, means that `l₁` is a sublist of
a permutation of `l₂`. This is an analogue of `l₁ ⊆ l₂` which respects
multiplicities of elements, and is used for the `≤` relation on multisets. -/
def subperm (l₁ l₂ : list α) : Prop := ∃ l ~ l₁, l <+ l₂
infix ` <+~ `:50 := subperm
theorem nil_subperm {l : list α} : [] <+~ l :=
⟨[], perm.nil, by simp⟩
theorem perm.subperm_left {l l₁ l₂ : list α} (p : l₁ ~ l₂) : l <+~ l₁ ↔ l <+~ l₂ :=
suffices ∀ {l₁ l₂ : list α}, l₁ ~ l₂ → l <+~ l₁ → l <+~ l₂,
from ⟨this p, this p.symm⟩,
λ l₁ l₂ p ⟨u, pu, su⟩,
let ⟨v, pv, sv⟩ := exists_perm_sublist su p in
⟨v, pv.trans pu, sv⟩
theorem perm.subperm_right {l₁ l₂ l : list α} (p : l₁ ~ l₂) : l₁ <+~ l ↔ l₂ <+~ l :=
⟨λ ⟨u, pu, su⟩, ⟨u, pu.trans p, su⟩,
λ ⟨u, pu, su⟩, ⟨u, pu.trans p.symm, su⟩⟩
theorem subperm_of_sublist {l₁ l₂ : list α} (s : l₁ <+ l₂) : l₁ <+~ l₂ :=
⟨l₁, perm.refl _, s⟩
theorem subperm_of_perm {l₁ l₂ : list α} (p : l₁ ~ l₂) : l₁ <+~ l₂ :=
⟨l₂, p.symm, sublist.refl _⟩
theorem subperm.refl (l : list α) : l <+~ l := subperm_of_perm (perm.refl _)
theorem subperm.trans {l₁ l₂ l₃ : list α} : l₁ <+~ l₂ → l₂ <+~ l₃ → l₁ <+~ l₃
| s ⟨l₂', p₂, s₂⟩ :=
let ⟨l₁', p₁, s₁⟩ := p₂.subperm_left.2 s in ⟨l₁', p₁, s₁.trans s₂⟩
theorem length_le_of_subperm {l₁ l₂ : list α} : l₁ <+~ l₂ → length l₁ ≤ length l₂
| ⟨l, p, s⟩ := perm_length p ▸ length_le_of_sublist s
theorem subperm.perm_of_length_le {l₁ l₂ : list α} : l₁ <+~ l₂ → length l₂ ≤ length l₁ → l₁ ~ l₂
| ⟨l, p, s⟩ h :=
suffices l = l₂, from this ▸ p.symm,
eq_of_sublist_of_length_le s $ perm_length p.symm ▸ h
theorem subperm.antisymm {l₁ l₂ : list α} (h₁ : l₁ <+~ l₂) (h₂ : l₂ <+~ l₁) : l₁ ~ l₂ :=
h₁.perm_of_length_le (length_le_of_subperm h₂)
theorem subset_of_subperm {l₁ l₂ : list α} : l₁ <+~ l₂ → l₁ ⊆ l₂
| ⟨l, p, s⟩ := subset.trans (perm_subset p.symm) (subset_of_sublist s)
end subperm
theorem exists_perm_append_of_sublist : ∀ {l₁ l₂ : list α}, l₁ <+ l₂ → ∃ l, l₂ ~ l₁ ++ l
| ._ ._ sublist.slnil := ⟨nil, perm.refl _⟩
| ._ ._ (sublist.cons l₁ l₂ a s) :=
let ⟨l, p⟩ := exists_perm_append_of_sublist s in
⟨a::l, (skip a p).trans perm_middle.symm⟩
| ._ ._ (sublist.cons2 l₁ l₂ a s) :=
let ⟨l, p⟩ := exists_perm_append_of_sublist s in
⟨l, skip a p⟩
theorem perm_countp (p : α → Prop) [decidable_pred p]
{l₁ l₂ : list α} (s : l₁ ~ l₂) : countp p l₁ = countp p l₂ :=
by rw [countp_eq_length_filter, countp_eq_length_filter];
exact perm_length (perm_filter _ s)
theorem countp_le_of_subperm (p : α → Prop) [decidable_pred p]
{l₁ l₂ : list α} : l₁ <+~ l₂ → countp p l₁ ≤ countp p l₂
| ⟨l, p', s⟩ := perm_countp p p' ▸ countp_le_of_sublist s
theorem perm_count [decidable_eq α] {l₁ l₂ : list α}
(p : l₁ ~ l₂) (a) : count a l₁ = count a l₂ :=
perm_countp _ p
theorem count_le_of_subperm [decidable_eq α] {l₁ l₂ : list α}
(s : l₁ <+~ l₂) (a) : count a l₁ ≤ count a l₂ :=
countp_le_of_subperm _ s
theorem foldl_eq_of_perm {f : β → α → β} {l₁ l₂ : list α} (rcomm : right_commutative f) (p : l₁ ~ l₂) :
∀ b, foldl f b l₁ = foldl f b l₂ :=
perm_induction_on p
(λ b, rfl)
(λ x t₁ t₂ p r b, r (f b x))
(λ x y t₁ t₂ p r b, by simp; rw rcomm; exact r (f (f b x) y))
(λ t₁ t₂ t₃ p₁ p₂ r₁ r₂ b, eq.trans (r₁ b) (r₂ b))
theorem foldr_eq_of_perm {f : α → β → β} {l₁ l₂ : list α} (lcomm : left_commutative f) (p : l₁ ~ l₂) :
∀ b, foldr f b l₁ = foldr f b l₂ :=
perm_induction_on p
(λ b, rfl)
(λ x t₁ t₂ p r b, by simp; rw [r b])
(λ x y t₁ t₂ p r b, by simp; rw [lcomm, r b])
(λ t₁ t₂ t₃ p₁ p₂ r₁ r₂ a, eq.trans (r₁ a) (r₂ a))
lemma rec_heq_of_perm {β : list α → Sort*} {f : Πa l, β l → β (a::l)} {b : β []} {l l' : list α}
(hl : perm l l')
(f_congr : ∀{a l l' b b'}, perm l l' → b == b' → f a l b == f a l' b')
(f_swap : ∀{a a' l b}, f a (a'::l) (f a' l b) == f a' (a::l) (f a l b)) :
@list.rec α β b f l == @list.rec α β b f l' :=
begin
induction hl,
case list.perm.nil { refl },
case list.perm.skip : a l l' h ih { exact f_congr h ih },
case list.perm.swap : a a' l { exact f_swap },
case list.perm.trans : l₁ l₂ l₃ h₁ h₂ ih₁ ih₂ { exact heq.trans ih₁ ih₂ }
end
section
variables {op : α → α → α} [is_associative α op] [is_commutative α op]
local notation a * b := op a b
local notation l <*> a := foldl op a l
lemma fold_op_eq_of_perm {l₁ l₂ : list α} {a : α} (h : l₁ ~ l₂) : l₁ <*> a = l₂ <*> a :=
foldl_eq_of_perm (right_comm _ (is_commutative.comm _) (is_associative.assoc _)) h _
end
section comm_monoid
open list
variable [comm_monoid α]
@[to_additive list.sum_eq_of_perm]
lemma prod_eq_of_perm {l₁ l₂ : list α} (h : perm l₁ l₂) : prod l₁ = prod l₂ :=
by induction h; simp [*, mul_left_comm]
@[to_additive list.sum_reverse]
lemma prod_reverse (l : list α) : prod l.reverse = prod l :=
prod_eq_of_perm $ reverse_perm l
end comm_monoid
theorem perm_inv_core {a : α} {l₁ l₂ r₁ r₂ : list α} : l₁++a::r₁ ~ l₂++a::r₂ → l₁++r₁ ~ l₂++r₂ :=
begin
generalize e₁ : l₁++a::r₁ = s₁, generalize e₂ : l₂++a::r₂ = s₂,
intro p, revert l₁ l₂ r₁ r₂ e₁ e₂,
refine perm_induction_on p _ (λ x t₁ t₂ p IH, _) (λ x y t₁ t₂ p IH, _) (λ t₁ t₂ t₃ p₁ p₂ IH₁ IH₂, _);
intros l₁ l₂ r₁ r₂ e₁ e₂,
{ apply (not_mem_nil a).elim, rw ← e₁, simp },
{ cases l₁ with y l₁; cases l₂ with z l₂;
dsimp at e₁ e₂; injections; subst x,
{ substs t₁ t₂, exact p },
{ substs z t₁ t₂, exact p.trans perm_middle },
{ substs y t₁ t₂, exact perm_middle.symm.trans p },
{ substs z t₁ t₂, exact skip y (IH rfl rfl) } },
{ rcases l₁ with _|⟨y, _|⟨z, l₁⟩⟩; rcases l₂ with _|⟨u, _|⟨v, l₂⟩⟩;
dsimp at e₁ e₂; injections; substs x y,
{ substs r₁ r₂, exact skip a p },
{ substs r₁ r₂, exact skip u p },
{ substs r₁ v t₂, exact skip u (p.trans perm_middle) },
{ substs r₁ r₂, exact skip y p },
{ substs r₁ r₂ y u, exact skip a p },
{ substs r₁ u v t₂, exact (skip y $ p.trans perm_middle).trans (swap _ _ _) },
{ substs r₂ z t₁, exact skip y (perm_middle.symm.trans p) },
{ substs r₂ y z t₁, exact (swap _ _ _).trans (skip u $ perm_middle.symm.trans p) },
{ substs u v t₁ t₂, exact (IH rfl rfl).swap' _ _ } },
{ substs t₁ t₃,
have : a ∈ t₂ := perm_subset p₁ (by simp),
rcases mem_split this with ⟨l₂, r₂, e₂⟩,
subst t₂, exact (IH₁ rfl rfl).trans (IH₂ rfl rfl) }
end
theorem perm_cons_inv {a : α} {l₁ l₂ : list α} : a::l₁ ~ a::l₂ → l₁ ~ l₂ :=
@perm_inv_core _ _ [] [] _ _
theorem perm_cons (a : α) {l₁ l₂ : list α} : a::l₁ ~ a::l₂ ↔ l₁ ~ l₂ :=
⟨perm_cons_inv, skip a⟩
theorem perm_app_left_iff {l₁ l₂ : list α} : ∀ l, l++l₁ ~ l++l₂ ↔ l₁ ~ l₂
| [] := iff.rfl
| (a::l) := (perm_cons a).trans (perm_app_left_iff l)
theorem perm_app_right_iff {l₁ l₂ : list α} (l) : l₁++l ~ l₂++l ↔ l₁ ~ l₂ :=
⟨λ p, (perm_app_left_iff _).1 $ trans perm_app_comm $ trans p perm_app_comm,
perm_app_left _⟩
theorem perm_option_to_list {o₁ o₂ : option α} : o₁.to_list ~ o₂.to_list ↔ o₁ = o₂ :=
begin
refine ⟨λ p, _, λ e, e ▸ perm.refl _⟩,
cases o₁ with a; cases o₂ with b, {refl},
{ cases (perm_length p) },
{ cases (perm_length p) },
{ exact option.mem_to_list.1 ((mem_of_perm p).2 $ by simp) }
end
theorem subperm_cons (a : α) {l₁ l₂ : list α} : a::l₁ <+~ a::l₂ ↔ l₁ <+~ l₂ :=
⟨λ ⟨l, p, s⟩, begin
cases s with _ _ _ s' u _ _ s',
{ exact (p.subperm_left.2 $ subperm_of_sublist $ sublist_cons _ _).trans
(subperm_of_sublist s') },
{ exact ⟨u, perm_cons_inv p, s'⟩ }
end, λ ⟨l, p, s⟩, ⟨a::l, skip a p, s.cons2 _ _ _⟩⟩
theorem cons_subperm_of_mem {a : α} {l₁ l₂ : list α} (d₁ : nodup l₁) (h₁ : a ∉ l₁) (h₂ : a ∈ l₂)
(s : l₁ <+~ l₂) : a :: l₁ <+~ l₂ :=
begin
rcases s with ⟨l, p, s⟩,
induction s generalizing l₁,
case list.sublist.slnil { cases h₂ },
case list.sublist.cons : r₁ r₂ b s' ih {
simp at h₂,
cases h₂ with e m,
{ subst b, exact ⟨a::r₁, skip a p, s'.cons2 _ _ _⟩ },
{ rcases ih m d₁ h₁ p with ⟨t, p', s'⟩, exact ⟨t, p', s'.cons _ _ _⟩ } },
case list.sublist.cons2 : r₁ r₂ b s' ih {
have bm : b ∈ l₁ := (perm_subset p $ mem_cons_self _ _),
have am : a ∈ r₂ := h₂.resolve_left (λ e, h₁ $ e.symm ▸ bm),
rcases mem_split bm with ⟨t₁, t₂, rfl⟩,
have st : t₁ ++ t₂ <+ t₁ ++ b :: t₂ := by simp,
rcases ih am (nodup_of_sublist st d₁)
(mt (λ x, subset_of_sublist st x) h₁)
(perm_cons_inv $ p.trans perm_middle) with ⟨t, p', s'⟩,
exact ⟨b::t, (skip b p').trans $ (swap _ _ _).trans (skip a perm_middle.symm), s'.cons2 _ _ _⟩ }
end
theorem subperm_app_left {l₁ l₂ : list α} : ∀ l, l++l₁ <+~ l++l₂ ↔ l₁ <+~ l₂
| [] := iff.rfl
| (a::l) := (subperm_cons a).trans (subperm_app_left l)
theorem subperm_app_right {l₁ l₂ : list α} (l) : l₁++l <+~ l₂++l ↔ l₁ <+~ l₂ :=
(perm_app_comm.subperm_left.trans perm_app_comm.subperm_right).trans (subperm_app_left l)
theorem subperm.exists_of_length_lt {l₁ l₂ : list α} :
l₁ <+~ l₂ → length l₁ < length l₂ → ∃ a, a :: l₁ <+~ l₂
| ⟨l, p, s⟩ h :=
suffices length l < length l₂ → ∃ (a : α), a :: l <+~ l₂, from
(this $ perm_length p.symm ▸ h).imp (λ a, (skip a p).subperm_right.1),
begin
clear subperm.exists_of_length_lt p h l₁, rename l₂ u,
induction s with l₁ l₂ a s IH _ _ b s IH; intro h,
{ cases h },
{ cases lt_or_eq_of_le (nat.le_of_lt_succ h : length l₁ ≤ length l₂) with h h,
{ exact (IH h).imp (λ a s, s.trans (subperm_of_sublist $ sublist_cons _ _)) },
{ exact ⟨a, eq_of_sublist_of_length_eq s h ▸ subperm.refl _⟩ } },
{ exact (IH $ nat.lt_of_succ_lt_succ h).imp
(λ a s, (swap _ _ _).subperm_right.1 $ (subperm_cons _).2 s) }
end
theorem subperm_of_subset_nodup
{l₁ l₂ : list α} (d : nodup l₁) (H : l₁ ⊆ l₂) : l₁ <+~ l₂ :=
begin
induction d with a l₁' h d IH,
{ exact ⟨nil, perm.nil, nil_sublist _⟩ },
{ cases forall_mem_cons.1 H with H₁ H₂,
simp at h,
exact cons_subperm_of_mem d h H₁ (IH H₂) }
end
theorem perm_ext {l₁ l₂ : list α} (d₁ : nodup l₁) (d₂ : nodup l₂) : l₁ ~ l₂ ↔ ∀a, a ∈ l₁ ↔ a ∈ l₂ :=
⟨λ p a, mem_of_perm p, λ H, subperm.antisymm
(subperm_of_subset_nodup d₁ (λ a, (H a).1))
(subperm_of_subset_nodup d₂ (λ a, (H a).2))⟩
theorem perm_ext_sublist_nodup {l₁ l₂ l : list α} (d : nodup l)
(s₁ : l₁ <+ l) (s₂ : l₂ <+ l) : l₁ ~ l₂ ↔ l₁ = l₂ :=
⟨λ h, begin
induction s₂ with l₂ l a s₂ IH l₂ l a s₂ IH generalizing l₁,
{ exact eq_nil_of_perm_nil h.symm },
{ simp at d,
cases s₁ with _ _ _ s₁ l₁ _ _ s₁,
{ exact IH d.2 s₁ h },
{ apply d.1.elim,
exact subset_of_subperm ⟨_, h.symm, s₂⟩ (mem_cons_self _ _) } },
{ simp at d,
cases s₁ with _ _ _ s₁ l₁ _ _ s₁,
{ apply d.1.elim,
exact subset_of_subperm ⟨_, h, s₁⟩ (mem_cons_self _ _) },
{ rw IH d.2 s₁ (perm_cons_inv h) } }
end, λ h, by rw h⟩
section
variable [decidable_eq α]
-- attribute [congr]
theorem erase_perm_erase (a : α) {l₁ l₂ : list α} (p : l₁ ~ l₂) :
l₁.erase a ~ l₂.erase a :=
if h₁ : a ∈ l₁ then
have h₂ : a ∈ l₂, from perm_subset p h₁,
perm_cons_inv $ trans (perm_erase h₁).symm $ trans p (perm_erase h₂)
else
have h₂ : a ∉ l₂, from mt (mem_of_perm p).2 h₁,
by rw [erase_of_not_mem h₁, erase_of_not_mem h₂]; exact p
theorem erase_subperm (a : α) (l : list α) : l.erase a <+~ l :=
⟨l.erase a, perm.refl _, erase_sublist _ _⟩
theorem erase_subperm_erase {l₁ l₂ : list α} (a : α) (h : l₁ <+~ l₂) : l₁.erase a <+~ l₂.erase a :=
let ⟨l, hp, hs⟩ := h in ⟨l.erase a, erase_perm_erase _ hp, erase_sublist_erase _ hs⟩
theorem perm_diff_left {l₁ l₂ : list α} (t : list α) (h : l₁ ~ l₂) : l₁.diff t ~ l₂.diff t :=
by induction t generalizing l₁ l₂ h; simp [*, erase_perm_erase]
theorem perm_diff_right (l : list α) {t₁ t₂ : list α} (h : t₁ ~ t₂) : l.diff t₁ = l.diff t₂ :=
by induction h generalizing l; simp [*, erase_perm_erase, erase_comm]
<|> exact (ih_1 _).trans (ih_2 _)
theorem subperm_cons_diff {a : α} : ∀ {l₁ l₂ : list α}, (a :: l₁).diff l₂ <+~ a :: l₁.diff l₂
| l₁ [] := ⟨a::l₁, by simp⟩
| l₁ (b::l₂) :=
begin
repeat {rw diff_cons},
by_cases heq : a = b,
{ by_cases b ∈ l₁,
{ rw perm.subperm_right, apply subperm_cons_diff,
simp [perm_diff_left, heq, perm_erase h] },
{ simp [subperm_of_sublist, sublist.cons, h, heq] } },
{ simp [heq, subperm_cons_diff] }
end
theorem subset_cons_diff {a : α} {l₁ l₂ : list α} : (a :: l₁).diff l₂ ⊆ a :: l₁.diff l₂ :=
subset_of_subperm subperm_cons_diff
theorem perm_bag_inter_left {l₁ l₂ : list α} (t : list α) (h : l₁ ~ l₂) : l₁.bag_inter t ~ l₂.bag_inter t :=
begin
induction h with x _ _ _ _ x y _ _ _ _ _ _ ih_1 ih_2 generalizing t, {simp},
{ by_cases x ∈ t; simp [*, skip] },
{ by_cases x = y, {simp [h]},
by_cases xt : x ∈ t; by_cases yt : y ∈ t,
{ simp [xt, yt, mem_erase_of_ne h, mem_erase_of_ne (ne.symm h), erase_comm, swap] },
{ simp [xt, yt, mt mem_of_mem_erase, skip] },
{ simp [xt, yt, mt mem_of_mem_erase, skip] },
{ simp [xt, yt] } },
{ exact (ih_1 _).trans (ih_2 _) }
end
theorem perm_bag_inter_right (l : list α) {t₁ t₂ : list α} (p : t₁ ~ t₂) : l.bag_inter t₁ = l.bag_inter t₂ :=
begin
induction l with a l IH generalizing t₁ t₂ p, {simp},
by_cases a ∈ t₁,
{ simp [h, (mem_of_perm p).1 h, IH (erase_perm_erase _ p)] },
{ simp [h, mt (mem_of_perm p).2 h, IH p] }
end
theorem cons_perm_iff_perm_erase {a : α} {l₁ l₂ : list α} : a::l₁ ~ l₂ ↔ a ∈ l₂ ∧ l₁ ~ l₂.erase a :=
⟨λ h, have a ∈ l₂, from perm_subset h (mem_cons_self a l₁),
⟨this, perm_cons_inv $ h.trans $ perm_erase this⟩,
λ ⟨m, h⟩, trans (skip a h) (perm_erase m).symm⟩
theorem perm_iff_count {l₁ l₂ : list α} : l₁ ~ l₂ ↔ ∀ a, count a l₁ = count a l₂ :=
⟨perm_count, λ H, begin
induction l₁ with a l₁ IH generalizing l₂,
{ cases l₂ with b l₂, {refl},
specialize H b, simp at H, contradiction },
{ have : a ∈ l₂ := count_pos.1 (by rw ← H; simp; apply nat.succ_pos),
refine trans (skip a $ IH $ λ b, _) (perm_erase this).symm,
specialize H b,
rw perm_count (perm_erase this) at H,
by_cases b = a; simp [h] at H ⊢; assumption }
end⟩
instance decidable_perm : ∀ (l₁ l₂ : list α), decidable (l₁ ~ l₂)
| [] [] := is_true $ perm.refl _
| [] (b::l₂) := is_false $ λ h, by have := eq_nil_of_perm_nil h; contradiction
| (a::l₁) l₂ := by haveI := decidable_perm l₁ (l₂.erase a);
exact decidable_of_iff' _ cons_perm_iff_perm_erase
-- @[congr]
theorem perm_erase_dup_of_perm {l₁ l₂ : list α} (p : l₁ ~ l₂) :
erase_dup l₁ ~ erase_dup l₂ :=
perm_iff_count.2 $ λ a,
if h : a ∈ l₁
then by simp [nodup_erase_dup, h, perm_subset p h]
else by simp [h, mt (mem_of_perm p).2 h]
-- attribute [congr]
theorem perm_insert (a : α)
{l₁ l₂ : list α} (p : l₁ ~ l₂) : insert a l₁ ~ insert a l₂ :=
if h : a ∈ l₁
then by simpa [h, perm_subset p h] using p
else by simpa [h, mt (mem_of_perm p).2 h] using skip a p
theorem perm_insert_swap (x y : α) (l : list α) :
insert x (insert y l) ~ insert y (insert x l) :=
begin
by_cases xl : x ∈ l; by_cases yl : y ∈ l; simp [xl, yl],
by_cases xy : x = y, { simp [xy] },
simp [not_mem_cons_of_ne_of_not_mem xy xl,
not_mem_cons_of_ne_of_not_mem (ne.symm xy) yl],
constructor
end
theorem perm_union_left {l₁ l₂ : list α} (t₁ : list α) (h : l₁ ~ l₂) : l₁ ∪ t₁ ~ l₂ ∪ t₁ :=
begin
induction h with a _ _ _ ih _ _ _ _ _ _ _ _ ih_1 ih_2; try {simp},
{ exact perm_insert a ih },
{ apply perm_insert_swap },
{ exact ih_1.trans ih_2 }
end
theorem perm_union_right (l : list α) {t₁ t₂ : list α} (h : t₁ ~ t₂) : l ∪ t₁ ~ l ∪ t₂ :=
by induction l; simp [*, perm_insert]
-- @[congr]
theorem perm_union {l₁ l₂ t₁ t₂ : list α} (p₁ : l₁ ~ l₂) (p₂ : t₁ ~ t₂) : l₁ ∪ t₁ ~ l₂ ∪ t₂ :=
trans (perm_union_left t₁ p₁) (perm_union_right l₂ p₂)
theorem perm_inter_left {l₁ l₂ : list α} (t₁ : list α) : l₁ ~ l₂ → l₁ ∩ t₁ ~ l₂ ∩ t₁ :=
perm_filter _
theorem perm_inter_right (l : list α) {t₁ t₂ : list α} (p : t₁ ~ t₂) : l ∩ t₁ = l ∩ t₂ :=
by dsimp [(∩), list.inter]; congr; funext a; rw [mem_of_perm p]
-- @[congr]
theorem perm_inter {l₁ l₂ t₁ t₂ : list α} (p₁ : l₁ ~ l₂) (p₂ : t₁ ~ t₂) : l₁ ∩ t₁ ~ l₂ ∩ t₂ :=
perm_inter_right l₂ p₂ ▸ perm_inter_left t₁ p₁
end
theorem perm_pairwise {R : α → α → Prop} (S : symmetric R) :
∀ {l₁ l₂ : list α} (p : l₁ ~ l₂), pairwise R l₁ ↔ pairwise R l₂ :=
suffices ∀ {l₁ l₂}, l₁ ~ l₂ → pairwise R l₁ → pairwise R l₂, from λ l₁ l₂ p, ⟨this p, this p.symm⟩,
λ l₁ l₂ p d, begin
induction d with a l₁ h d IH generalizing l₂,
{ rw eq_nil_of_perm_nil p, constructor },
{ have : a ∈ l₂ := perm_subset p (mem_cons_self _ _),
rcases mem_split this with ⟨s₂, t₂, rfl⟩,
have p' := perm_cons_inv (p.trans perm_middle),
refine (pairwise_middle S).2 (pairwise_cons.2 ⟨λ b m, _, IH _ p'⟩),
exact h _ (perm_subset p'.symm m) }
end
theorem perm_nodup {l₁ l₂ : list α} : l₁ ~ l₂ → (nodup l₁ ↔ nodup l₂) :=
perm_pairwise $ @ne.symm α
theorem perm_bind_left {l₁ l₂ : list α} (f : α → list β) (p : l₁ ~ l₂) :
l₁.bind f ~ l₂.bind f :=
begin
induction p with a l₁ l₂ p IH a b l l₁ l₂ l₃ p₁ p₂ IH₁ IH₂, {simp},
{ simp, exact perm_app_right _ IH },
{ simp, rw [← append_assoc, ← append_assoc], exact perm_app_left _ perm_app_comm },
{ exact trans IH₁ IH₂ }
end
theorem perm_bind_right (l : list α) {f g : α → list β} (h : ∀ a, f a ~ g a) :
l.bind f ~ l.bind g :=
by induction l with a l IH; simp; exact perm_app (h a) IH
theorem perm_product_left {l₁ l₂ : list α} (t₁ : list β) (p : l₁ ~ l₂) : product l₁ t₁ ~ product l₂ t₁ :=
perm_bind_left _ p
theorem perm_product_right (l : list α) {t₁ t₂ : list β} (p : t₁ ~ t₂) : product l t₁ ~ product l t₂ :=
perm_bind_right _ $ λ a, perm_map _ p
@[congr] theorem perm_product {l₁ l₂ : list α} {t₁ t₂ : list β}
(p₁ : l₁ ~ l₂) (p₂ : t₁ ~ t₂) : product l₁ t₁ ~ product l₂ t₂ :=
trans (perm_product_left t₁ p₁) (perm_product_right l₂ p₂)
theorem sublists_cons_perm_append (a : α) (l : list α) :
sublists (a :: l) ~ sublists l ++ map (cons a) (sublists l) :=
begin
simp [sublists, sublists_aux_cons_cons],
refine skip _ ((skip _ _).trans perm_middle.symm),
induction sublists_aux l cons with b l IH; simp,
exact skip b ((skip _ IH).trans perm_middle.symm)
end
theorem sublists_perm_sublists' : ∀ l : list α, sublists l ~ sublists' l
| [] := perm.refl _
| (a::l) := let IH := sublists_perm_sublists' l in
by rw sublists'_cons; exact
(sublists_cons_perm_append _ _).trans (perm_app IH (perm_map _ IH))
theorem revzip_sublists (l : list α) :
∀ l₁ l₂, (l₁, l₂) ∈ revzip l.sublists → l₁ ++ l₂ ~ l :=
begin
rw revzip,
apply list.reverse_rec_on l,
{ intros l₁ l₂ h, simp at h, simp [h] },
{ intros l a IH l₁ l₂ h,
rw [sublists_concat, reverse_append, zip_append, ← map_reverse,
zip_map_right, zip_map_left] at h; [simp at h, simp],
rcases h with ⟨l₁, l₂', h, rfl, rfl⟩ | ⟨l₁', l₂, h, rfl, rfl⟩,
{ rw ← append_assoc,
exact perm_app_left _ (IH _ _ h) },
{ rw append_assoc,
apply (perm_app_right _ perm_app_comm).trans,
rw ← append_assoc,
exact perm_app_left _ (IH _ _ h) } }
end
theorem revzip_sublists' (l : list α) :
∀ l₁ l₂, (l₁, l₂) ∈ revzip l.sublists' → l₁ ++ l₂ ~ l :=
begin
rw revzip,
induction l with a l IH; intros l₁ l₂ h,
{ simp at h, simp [h] },
{ rw [sublists'_cons, reverse_append, zip_append, ← map_reverse,
zip_map_right, zip_map_left] at h; [simp at h, simp],
rcases h with ⟨l₁, l₂', h, rfl, rfl⟩ | ⟨l₁', l₂, h, rfl, rfl⟩,
{ exact perm_middle.trans (skip _ (IH _ _ h)) },
{ exact skip _ (IH _ _ h) } }
end
theorem perm_lookmap (f : α → option α) {l₁ l₂ : list α}
(H : pairwise (λ a b, ∀ (c ∈ f a) (d ∈ f b), a = b ∧ c = d) l₁)
(p : l₁ ~ l₂) : lookmap f l₁ ~ lookmap f l₂ :=
begin
let F := λ a b, ∀ (c ∈ f a) (d ∈ f b), a = b ∧ c = d,
change pairwise F l₁ at H,
induction p with a l₁ l₂ p IH a b l l₁ l₂ l₃ p₁ p₂ IH₁ IH₂, {simp},
{ cases h : f a,
{ simp [h], exact (IH (pairwise_cons.1 H).2).skip _ },
{ simp [lookmap_cons_some _ _ h], exact p.skip _ } },
{ cases h₁ : f a with c; cases h₂ : f b with d,
{ simp [h₁, h₂], apply swap },
{ simp [h₁, lookmap_cons_some _ _ h₂], apply swap },
{ simp [lookmap_cons_some _ _ h₁, h₂], apply swap },
{ simp [lookmap_cons_some _ _ h₁, lookmap_cons_some _ _ h₂],
rcases (pairwise_cons.1 H).1 _ (or.inl rfl) _ h₂ _ h₁ with ⟨rfl, rfl⟩,
refl } },
{ refine (IH₁ H).trans (IH₂ ((perm_pairwise _ p₁).1 H)),
exact λ a b h c h₁ d h₂, (h d h₂ c h₁).imp eq.symm eq.symm }
end
theorem perm_erasep (f : α → Prop) [decidable_pred f] {l₁ l₂ : list α}
(H : pairwise (λ a b, f a → f b → false) l₁)
(p : l₁ ~ l₂) : erasep f l₁ ~ erasep f l₂ :=
begin
let F := λ a b, f a → f b → false,
change pairwise F l₁ at H,
induction p with a l₁ l₂ p IH a b l l₁ l₂ l₃ p₁ p₂ IH₁ IH₂, {simp},
{ by_cases h : f a,
{ simp [h, p] },
{ simp [h], exact (IH (pairwise_cons.1 H).2).skip _ } },
{ by_cases h₁ : f a; by_cases h₂ : f b; simp [h₁, h₂],
{ cases (pairwise_cons.1 H).1 _ (or.inl rfl) h₂ h₁ },
{ apply swap } },
{ refine (IH₁ H).trans (IH₂ ((perm_pairwise _ p₁).1 H)),
exact λ a b h h₁ h₂, h h₂ h₁ }
end
/- enumerating permutations -/
section permutations
theorem permutations_aux2_fst (t : α) (ts : list α) (r : list β) : ∀ (ys : list α) (f : list α → β),
(permutations_aux2 t ts r ys f).1 = ys ++ ts
| [] f := rfl
| (y::ys) f := match _, permutations_aux2_fst ys _ : ∀ o : list α × list β, o.1 = ys ++ ts →
(permutations_aux2._match_1 t y f o).1 = y :: ys ++ ts with
| ⟨_, zs⟩, rfl := rfl
end
@[simp] theorem permutations_aux2_snd_nil (t : α) (ts : list α) (r : list β) (f : list α → β) :
(permutations_aux2 t ts r [] f).2 = r := rfl
@[simp] theorem permutations_aux2_snd_cons (t : α) (ts : list α) (r : list β) (y : α) (ys : list α) (f : list α → β) :
(permutations_aux2 t ts r (y::ys) f).2 = f (t :: y :: ys ++ ts) ::
(permutations_aux2 t ts r ys (λx : list α, f (y::x))).2 :=
match _, permutations_aux2_fst t ts r _ _ : ∀ o : list α × list β, o.1 = ys ++ ts →
(permutations_aux2._match_1 t y f o).2 = f (t :: y :: ys ++ ts) :: o.2 with
| ⟨_, zs⟩, rfl := rfl
end
theorem permutations_aux2_append (t : α) (ts : list α) (r : list β) (ys : list α) (f : list α → β) :
(permutations_aux2 t ts nil ys f).2 ++ r = (permutations_aux2 t ts r ys f).2 :=
by induction ys generalizing f; simp *
theorem mem_permutations_aux2 {t : α} {ts : list α} {ys : list α} {l l' : list α} :
l' ∈ (permutations_aux2 t ts [] ys (append l)).2 ↔
∃ l₁ l₂, l₂ ≠ [] ∧ ys = l₁ ++ l₂ ∧ l' = l ++ l₁ ++ t :: l₂ ++ ts :=
begin
induction ys with y ys ih generalizing l,
{ simp {contextual := tt} },
{ rw [permutations_aux2_snd_cons, show (λ (x : list α), l ++ y :: x) = append (l ++ [y]),
by funext; simp, mem_cons_iff, ih], split; intro h,
{ rcases h with e | ⟨l₁, l₂, l0, ye, _⟩,
{ subst l', exact ⟨[], y::ys, by simp⟩ },
{ substs l' ys, exact ⟨y::l₁, l₂, l0, by simp⟩ } },
{ rcases h with ⟨_ | ⟨y', l₁⟩, l₂, l0, ye, rfl⟩,
{ simp [ye] },
{ simp at ye, rcases ye with ⟨rfl, rfl⟩,
exact or.inr ⟨l₁, l₂, l0, by simp⟩ } } }
end
theorem mem_permutations_aux2' {t : α} {ts : list α} {ys : list α} {l : list α} :
l ∈ (permutations_aux2 t ts [] ys id).2 ↔
∃ l₁ l₂, l₂ ≠ [] ∧ ys = l₁ ++ l₂ ∧ l = l₁ ++ t :: l₂ ++ ts :=
by rw [show @id (list α) = append nil, by funext; refl]; apply mem_permutations_aux2
theorem length_permutations_aux2 (t : α) (ts : list α) (ys : list α) (f : list α → β) :
length (permutations_aux2 t ts [] ys f).2 = length ys :=
by induction ys generalizing f; simp *
theorem foldr_permutations_aux2 (t : α) (ts : list α) (r L : list (list α)) :
foldr (λy r, (permutations_aux2 t ts r y id).2) r L = L.bind (λ y, (permutations_aux2 t ts [] y id).2) ++ r :=
by induction L with l L ih; [refl, {simp [ih], rw ← permutations_aux2_append}]
theorem mem_foldr_permutations_aux2 {t : α} {ts : list α} {r L : list (list α)} {l' : list α} :
l' ∈ foldr (λy r, (permutations_aux2 t ts r y id).2) r L ↔ l' ∈ r ∨
∃ l₁ l₂, l₁ ++ l₂ ∈ L ∧ l₂ ≠ [] ∧ l' = l₁ ++ t :: l₂ ++ ts :=
have (∃ (a : list α), a ∈ L ∧
∃ (l₁ l₂ : list α), ¬l₂ = nil ∧ a = l₁ ++ l₂ ∧ l' = l₁ ++ t :: (l₂ ++ ts)) ↔
∃ (l₁ l₂ : list α), ¬l₂ = nil ∧ l₁ ++ l₂ ∈ L ∧ l' = l₁ ++ t :: (l₂ ++ ts),
from ⟨λ ⟨a, aL, l₁, l₂, l0, e, h⟩, ⟨l₁, l₂, l0, e ▸ aL, h⟩,
λ ⟨l₁, l₂, l0, aL, h⟩, ⟨_, aL, l₁, l₂, l0, rfl, h⟩⟩,
by rw foldr_permutations_aux2; simp [mem_permutations_aux2', this,
or.comm, or.left_comm, or.assoc, and.comm, and.left_comm, and.assoc]
theorem length_foldr_permutations_aux2 (t : α) (ts : list α) (r L : list (list α)) :
length (foldr (λy r, (permutations_aux2 t ts r y id).2) r L) = sum (map length L) + length r :=
by simp [foldr_permutations_aux2, (∘), length_permutations_aux2]
theorem length_foldr_permutations_aux2' (t : α) (ts : list α) (r L : list (list α))
(n) (H : ∀ l ∈ L, length l = n) :
length (foldr (λy r, (permutations_aux2 t ts r y id).2) r L) = n * length L + length r :=
begin
rw [length_foldr_permutations_aux2, (_ : sum (map length L) = n * length L)],
induction L with l L ih, {simp},
simp [ih (λ l m, H l (mem_cons_of_mem _ m)), H l (mem_cons_self _ _), mul_add]
end
theorem perm_of_mem_permutations_aux :
∀ {ts is l : list α}, l ∈ permutations_aux ts is → l ~ ts ++ is :=
begin
refine permutations_aux.rec (by simp) _,
introv IH1 IH2 m,
rw [permutations_aux_cons, permutations, mem_foldr_permutations_aux2] at m,
rcases m with m | ⟨l₁, l₂, m, _, e⟩,
{ exact (IH1 m).trans perm_middle },
{ subst e,
have p : l₁ ++ l₂ ~ is,
{ simp [permutations] at m,
cases m with e m, {simp [e]},
exact is.append_nil ▸ IH2 m },
exact (perm_app_left _ (perm_middle.trans (skip _ p))).trans (skip _ perm_app_comm) }
end
theorem perm_of_mem_permutations {l₁ l₂ : list α}
(h : l₁ ∈ permutations l₂) : l₁ ~ l₂ :=
(eq_or_mem_of_mem_cons h).elim (λ e, e ▸ perm.refl _)
(λ m, append_nil l₂ ▸ perm_of_mem_permutations_aux m)
theorem length_permutations_aux :
∀ ts is : list α, length (permutations_aux ts is) + is.length.fact = (length ts + length is).fact :=
begin
refine permutations_aux.rec (by simp) _,
intros t ts is IH1 IH2,
have IH2 : length (permutations_aux is nil) + 1 = is.length.fact,
{ simpa using IH2 },
simp [-add_comm, nat.fact, nat.add_succ, mul_comm] at IH1,
rw [permutations_aux_cons,
length_foldr_permutations_aux2' _ _ _ _ _
(λ l m, perm_length (perm_of_mem_permutations m)),
permutations, length, length, IH2,
nat.succ_add, nat.fact_succ, mul_comm (nat.succ _), ← IH1,
add_comm (_*_), add_assoc, nat.mul_succ, mul_comm]
end
theorem length_permutations (l : list α) : length (permutations l) = (length l).fact :=
length_permutations_aux l []
theorem mem_permutations_of_perm_lemma {is l : list α}
(H : l ~ [] ++ is → (∃ ts' ~ [], l = ts' ++ is) ∨ l ∈ permutations_aux is [])
: l ~ is → l ∈ permutations is :=
by simpa [permutations, perm_nil] using H
theorem mem_permutations_aux_of_perm :
∀ {ts is l : list α}, l ~ is ++ ts → (∃ is' ~ is, l = is' ++ ts) ∨ l ∈ permutations_aux ts is :=
begin
refine permutations_aux.rec (by simp) _,
intros t ts is IH1 IH2 l p,
rw [permutations_aux_cons, mem_foldr_permutations_aux2],
rcases IH1 (p.trans perm_middle) with ⟨is', p', e⟩ | m,
{ clear p, subst e,
rcases mem_split (perm_subset p'.symm (mem_cons_self _ _)) with ⟨l₁, l₂, e⟩,
subst is',
have p := perm_cons_inv (perm_middle.symm.trans p'),
cases l₂ with a l₂',
{ exact or.inl ⟨l₁, by simpa using p⟩ },
{ exact or.inr (or.inr ⟨l₁, a::l₂',
mem_permutations_of_perm_lemma IH2 p, by simp⟩) } },
{ exact or.inr (or.inl m) }
end
@[simp] theorem mem_permutations (s t : list α) : s ∈ permutations t ↔ s ~ t :=
⟨perm_of_mem_permutations, mem_permutations_of_perm_lemma mem_permutations_aux_of_perm⟩
end permutations
end list
|
570bab492ed53fb52ee594a9d00f854a57faf905 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/analysis/convex/caratheodory.lean | 1ffbb069d37cd7f2327610e41389cefcc46002a3 | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 8,562 | lean | /-
Copyright (c) 2020 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johan Commelin, Scott Morrison
-/
import analysis.convex.combination
import linear_algebra.affine_space.independent
import tactic.field_simp
/-!
# Carathéodory's convexity theorem
Convex hull can be regarded as a refinement of affine span. Both are closure operators but whereas
convex hull takes values in the lattice of convex subsets, affine span takes values in the much
coarser sublattice of affine subspaces.
The cost of this refinement is that one no longer has bases. However Carathéodory's convexity
theorem offers some compensation. Given a set `s` together with a point `x` in its convex hull,
Carathéodory says that one may find an affine-independent family of elements `s` whose convex hull
contains `x`. Thus the difference from the case of affine span is that the affine-independent family
depends on `x`.
In particular, in finite dimensions Carathéodory's theorem implies that the convex hull of a set `s`
in `𝕜ᵈ` is the union of the convex hulls of the `(d + 1)`-tuples in `s`.
## Main results
* `convex_hull_eq_union`: Carathéodory's convexity theorem
## Implementation details
This theorem was formalized as part of the Sphere Eversion project.
## Tags
convex hull, caratheodory
-/
open set finset
open_locale big_operators
universes u
variables {𝕜 : Type*} {E : Type u} [linear_ordered_field 𝕜] [add_comm_group E] [module 𝕜 E]
namespace caratheodory
/-- If `x` is in the convex hull of some finset `t` whose elements are not affine-independent,
then it is in the convex hull of a strict subset of `t`. -/
lemma mem_convex_hull_erase [decidable_eq E] {t : finset E}
(h : ¬ affine_independent 𝕜 (coe : t → E)) {x : E} (m : x ∈ convex_hull 𝕜 (↑t : set E)) :
∃ (y : (↑t : set E)), x ∈ convex_hull 𝕜 (↑(t.erase y) : set E) :=
begin
simp only [finset.convex_hull_eq, mem_set_of_eq] at m ⊢,
obtain ⟨f, fpos, fsum, rfl⟩ := m,
obtain ⟨g, gcombo, gsum, gpos⟩ := exists_nontrivial_relation_sum_zero_of_not_affine_ind h,
replace gpos := exists_pos_of_sum_zero_of_exists_nonzero g gsum gpos,
clear h,
let s := @finset.filter _ (λ z, 0 < g z) (λ _, linear_order.decidable_lt _ _) t,
obtain ⟨i₀, mem, w⟩ : ∃ i₀ ∈ s, ∀ i ∈ s, f i₀ / g i₀ ≤ f i / g i,
{ apply s.exists_min_image (λ z, f z / g z),
obtain ⟨x, hx, hgx⟩ : ∃ x ∈ t, 0 < g x := gpos,
exact ⟨x, mem_filter.mpr ⟨hx, hgx⟩⟩ },
have hg : 0 < g i₀ := by { rw mem_filter at mem, exact mem.2 },
have hi₀ : i₀ ∈ t := filter_subset _ _ mem,
let k : E → 𝕜 := λ z, f z - (f i₀ / g i₀) * g z,
have hk : k i₀ = 0 := by field_simp [k, ne_of_gt hg],
have ksum : ∑ e in t.erase i₀, k e = 1,
{ calc ∑ e in t.erase i₀, k e = ∑ e in t, k e :
by conv_rhs { rw [← insert_erase hi₀, sum_insert (not_mem_erase i₀ t), hk, zero_add] }
... = ∑ e in t, (f e - f i₀ / g i₀ * g e) : rfl
... = 1 : by rw [sum_sub_distrib, fsum, ← mul_sum, gsum, mul_zero, sub_zero] },
refine ⟨⟨i₀, hi₀⟩, k, _, by convert ksum, _⟩,
{ simp only [and_imp, sub_nonneg, mem_erase, ne.def, subtype.coe_mk],
intros e hei₀ het,
by_cases hes : e ∈ s,
{ have hge : 0 < g e := by { rw mem_filter at hes, exact hes.2 },
rw ← le_div_iff hge,
exact w _ hes },
{ calc _ ≤ 0 : mul_nonpos_of_nonneg_of_nonpos _ _ -- prove two goals below
... ≤ f e : fpos e het,
{ apply div_nonneg (fpos i₀ (mem_of_subset (filter_subset _ t) mem)) (le_of_lt hg) },
{ simpa only [mem_filter, het, true_and, not_lt] using hes } } },
{ simp only [subtype.coe_mk, center_mass_eq_of_sum_1 _ id ksum, id],
calc ∑ e in t.erase i₀, k e • e = ∑ e in t, k e • e : sum_erase _ (by rw [hk, zero_smul])
... = ∑ e in t, (f e - f i₀ / g i₀ * g e) • e : rfl
... = t.center_mass f id : _,
simp only [sub_smul, mul_smul, sum_sub_distrib, ← smul_sum, gcombo, smul_zero,
sub_zero, center_mass, fsum, inv_one, one_smul, id.def] }
end
variables {s : set E} {x : E} (hx : x ∈ convex_hull 𝕜 s)
include hx
/-- Given a point `x` in the convex hull of a set `s`, this is a finite subset of `s` of minimum
cardinality, whose convex hull contains `x`. -/
noncomputable def min_card_finset_of_mem_convex_hull : finset E :=
function.argmin_on finset.card nat.lt_wf { t | ↑t ⊆ s ∧ x ∈ convex_hull 𝕜 (t : set E) }
(by simpa only [convex_hull_eq_union_convex_hull_finite_subsets s, exists_prop, mem_Union] using hx)
lemma min_card_finset_of_mem_convex_hull_subseteq : ↑(min_card_finset_of_mem_convex_hull hx) ⊆ s :=
(function.argmin_on_mem _ _ { t : finset E | ↑t ⊆ s ∧ x ∈ convex_hull 𝕜 (t : set E) } _).1
lemma mem_min_card_finset_of_mem_convex_hull :
x ∈ convex_hull 𝕜 (min_card_finset_of_mem_convex_hull hx : set E) :=
(function.argmin_on_mem _ _ { t : finset E | ↑t ⊆ s ∧ x ∈ convex_hull 𝕜 (t : set E) } _).2
lemma min_card_finset_of_mem_convex_hull_nonempty :
(min_card_finset_of_mem_convex_hull hx).nonempty :=
begin
rw [← finset.coe_nonempty, ← @convex_hull_nonempty_iff 𝕜],
exact ⟨x, mem_min_card_finset_of_mem_convex_hull hx⟩,
end
lemma min_card_finset_of_mem_convex_hull_card_le_card
{t : finset E} (ht₁ : ↑t ⊆ s) (ht₂ : x ∈ convex_hull 𝕜 (t : set E)) :
(min_card_finset_of_mem_convex_hull hx).card ≤ t.card :=
function.argmin_on_le _ _ _ ⟨ht₁, ht₂⟩
lemma affine_independent_min_card_finset_of_mem_convex_hull :
affine_independent 𝕜 (coe : min_card_finset_of_mem_convex_hull hx → E) :=
begin
let k := (min_card_finset_of_mem_convex_hull hx).card - 1,
have hk : (min_card_finset_of_mem_convex_hull hx).card = k + 1,
{ exact (nat.succ_pred_eq_of_pos
(finset.card_pos.mpr (min_card_finset_of_mem_convex_hull_nonempty hx))).symm },
classical,
by_contra,
obtain ⟨p, hp⟩ := mem_convex_hull_erase h (mem_min_card_finset_of_mem_convex_hull hx),
have contra := min_card_finset_of_mem_convex_hull_card_le_card hx (set.subset.trans
(finset.erase_subset ↑p (min_card_finset_of_mem_convex_hull hx))
(min_card_finset_of_mem_convex_hull_subseteq hx)) hp,
rw [← not_lt] at contra,
apply contra,
erw [card_erase_of_mem p.2, hk],
exact lt_add_one _,
end
end caratheodory
variables {s : set E}
/-- **Carathéodory's convexity theorem** -/
lemma convex_hull_eq_union :
convex_hull 𝕜 s =
⋃ (t : finset E) (hss : ↑t ⊆ s) (hai : affine_independent 𝕜 (coe : t → E)), convex_hull 𝕜 ↑t :=
begin
apply set.subset.antisymm,
{ intros x hx,
simp only [exists_prop, set.mem_Union],
exact ⟨caratheodory.min_card_finset_of_mem_convex_hull hx,
caratheodory.min_card_finset_of_mem_convex_hull_subseteq hx,
caratheodory.affine_independent_min_card_finset_of_mem_convex_hull hx,
caratheodory.mem_min_card_finset_of_mem_convex_hull hx⟩ },
{ iterate 3 { convert set.Union_subset _, intro },
exact convex_hull_mono ‹_› }
end
/-- A more explicit version of `convex_hull_eq_union`. -/
theorem eq_pos_convex_span_of_mem_convex_hull {x : E} (hx : x ∈ convex_hull 𝕜 s) :
∃ (ι : Sort (u+1)) (_ : fintype ι), by exactI ∃ (z : ι → E) (w : ι → 𝕜)
(hss : set.range z ⊆ s) (hai : affine_independent 𝕜 z)
(hw : ∀ i, 0 < w i), ∑ i, w i = 1 ∧ ∑ i, w i • z i = x :=
begin
rw convex_hull_eq_union at hx,
simp only [exists_prop, set.mem_Union] at hx,
obtain ⟨t, ht₁, ht₂, ht₃⟩ := hx,
simp only [t.convex_hull_eq, exists_prop, set.mem_set_of_eq] at ht₃,
obtain ⟨w, hw₁, hw₂, hw₃⟩ := ht₃,
let t' := t.filter (λ i, w i ≠ 0),
refine ⟨t', t'.fintype_coe_sort, (coe : t' → E), w ∘ (coe : t' → E), _, _, _, _, _⟩,
{ rw subtype.range_coe_subtype, exact subset.trans (finset.filter_subset _ t) ht₁ },
{ exact ht₂.comp_embedding
⟨_, inclusion_injective (finset.filter_subset (λ i, w i ≠ 0) t)⟩ },
{ exact λ i, (hw₁ _ (finset.mem_filter.mp i.2).1).lt_of_ne
(finset.mem_filter.mp i.property).2.symm },
{ erw [finset.sum_attach, finset.sum_filter_ne_zero, hw₂] },
{ change ∑ (i : t') in t'.attach, (λ e, w e • e) ↑i = x,
erw [finset.sum_attach, finset.sum_filter_of_ne],
{ rw t.center_mass_eq_of_sum_1 id hw₂ at hw₃, exact hw₃ },
{ intros e he hwe contra, apply hwe, rw [contra, zero_smul] } }
end
|
1b4dec5cf7ea13091bead33973723cb03632bc9d | 4727251e0cd73359b15b664c3170e5d754078599 | /src/category_theory/bicategory/single_obj.lean | 47022b6ab091218adfd9d81cd4ca21c26725185a | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 3,733 | lean | /-
Copyright (c) 2022 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import category_theory.bicategory.End
import category_theory.monoidal.functorial
/-!
# Promoting a monoidal category to a single object bicategory.
A monoidal category can be thought of as a bicategory with a single object.
The objects of the monoidal category become the 1-morphisms,
with composition given by tensor product,
and the morphisms of the monoidal category become the 2-morphisms.
We verify that the endomorphisms of that single object recovers the original monoidal category.
One could go much further: the bicategory of monoidal categories
(equipped with monoidal functors and monoidal natural transformations)
is equivalent to the bicategory consisting of
* single object bicategories,
* pseudofunctors, and
* (oplax) natural transformations `η` such that `η.app punit.star = 𝟙 _`.
-/
namespace category_theory
variables (C : Type*) [category C] [monoidal_category C]
/--
Promote a monoidal category to a bicategory with a single object.
(The objects of the monoidal category become the 1-morphisms,
with composition given by tensor product,
and the morphisms of the monoidal category become the 2-morphisms.)
-/
@[nolint unused_arguments, derive inhabited]
def monoidal_single_obj (C : Type*) [category C] [monoidal_category C] := punit
open monoidal_category
instance : bicategory (monoidal_single_obj C) :=
{ hom := λ _ _, C,
id := λ _, 𝟙_ C,
comp := λ _ _ _ X Y, X ⊗ Y,
whisker_left := λ _ _ _ X Y Z f, 𝟙 X ⊗ f,
whisker_right := λ _ _ _ X Y f Z, f ⊗ 𝟙 Z,
associator := λ _ _ _ _ X Y Z, α_ X Y Z,
left_unitor := λ _ _ X, λ_ X,
right_unitor := λ _ _ X, ρ_ X,
comp_whisker_left' :=
by { intros, rw [associator_inv_naturality, iso.hom_inv_id_assoc, tensor_id], },
whisker_assoc' := by { intros, rw [associator_inv_naturality, iso.hom_inv_id_assoc], },
whisker_right_comp' :=
by { intros, rw [←tensor_id, associator_naturality, iso.inv_hom_id_assoc], },
id_whisker_left' := by { intros, rw [left_unitor_inv_naturality, iso.hom_inv_id_assoc], },
whisker_right_id' := by { intros, rw [right_unitor_inv_naturality, iso.hom_inv_id_assoc], },
pentagon' := by { intros, rw [pentagon], }, }
namespace monoidal_single_obj
/-- The unique object in the bicategory obtained by "promoting" a monoidal category. -/
@[nolint unused_arguments]
protected def star : monoidal_single_obj C := punit.star
/--
The monoidal functor from the endomorphisms of the single object
when we promote a monoidal category to a single object bicategory,
to the original monoidal category.
We subsequently show this is an equivalence.
-/
@[simps]
def End_monoidal_star_functor : monoidal_functor (End_monoidal (monoidal_single_obj.star C)) C :=
{ obj := λ X, X,
map := λ X Y f, f,
ε := 𝟙 _,
μ := λ X Y, 𝟙 _,
μ_natural' := λ X Y X' Y' f g, begin
dsimp,
simp only [category.id_comp, category.comp_id],
-- Should we provide further simp lemmas so this goal becomes visible?
exact (tensor_id_comp_id_tensor _ _).symm,
end, }
noncomputable theory
/--
The equivalence between the endomorphisms of the single object
when we promote a monoidal category to a single object bicategory,
and the original monoidal category.
-/
def End_monoidal_star_functor_is_equivalence :
is_equivalence (End_monoidal_star_functor C).to_functor :=
{ inverse :=
{ obj := λ X, X,
map := λ X Y f, f, },
unit_iso := nat_iso.of_components (λ X, as_iso (𝟙 _)) (by tidy),
counit_iso := nat_iso.of_components (λ X, as_iso (𝟙 _)) (by tidy), }
end monoidal_single_obj
end category_theory
|
cd3c5cd8523a6b4c6920bd2f338dd7424fc07b22 | e00ea76a720126cf9f6d732ad6216b5b824d20a7 | /src/tactic/suggest.lean | 5cb7d9dee4732b3d74ee617b3923cadade8f2e87 | [
"Apache-2.0"
] | permissive | vaibhavkarve/mathlib | a574aaf68c0a431a47fa82ce0637f0f769826bfe | 17f8340912468f49bdc30acdb9a9fa02eeb0473a | refs/heads/master | 1,621,263,802,637 | 1,585,399,588,000 | 1,585,399,588,000 | 250,833,447 | 0 | 0 | Apache-2.0 | 1,585,410,341,000 | 1,585,410,341,000 | null | UTF-8 | Lean | false | false | 15,552 | lean | /-
Copyright (c) 2019 Lucas Allen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Lucas Allen and Scott Morrison
-/
import data.mllist
import tactic.solve_by_elim
/-!
# `suggest` and `library_search`
`suggest` and `library_search` are a pair of tactics for applying lemmas from the library to the
current goal.
* `suggest` prints a list of `exact ...` or `refine ...` statements, which may produce new goals
* `library_search` prints a single `exact ...` which closes the goal, or fails
-/
namespace tactic
open native
namespace suggest
/-- compute the head symbol of an expression, but normalise `>` to `<` and `≥` to `≤` -/
-- We may want to tweak this further?
meta def head_symbol : expr → name
| (expr.pi _ _ _ t) := head_symbol t
| (expr.app f _) := head_symbol f
| (expr.const n _) :=
-- TODO this is a hack; if you suspect more cases here would help, please report them
match n with
| `gt := `has_lt.lt
| `ge := `has_le.le
| _ := n
end
| _ := `_
/--
A declaration can match the head symbol of the current goal in four possible ways:
* `ex` : an exact match
* `mp` : the declaration returns an `iff`, and the right hand side matches the goal
* `mpr` : the declaration returns an `iff`, and the left hand side matches the goal
* `both`: the declaration returns an `iff`, and the both sides match the goal
-/
@[derive decidable_eq, derive inhabited]
inductive head_symbol_match
| ex | mp | mpr | both
open head_symbol_match
/-- a textual representation of a `head_symbol_match`, for trace debugging. -/
def head_symbol_match.to_string : head_symbol_match → string
| ex := "exact"
| mp := "iff.mp"
| mpr := "iff.mpr"
| both := "iff.mp and iff.mpr"
/--
When we are determining if a given declaration is potentially relevant for the current goal,
we compute `unfold_head_symbol` on the head symbol of the declaration, producing a list of names.
We consider the declaration potentially relevant if the head symbol of the goal appears in this
list.
-/
-- This is a hack.
meta def unfold_head_symbol : name → list name
| `false := [`not, `false]
| n := [n]
/-- Determine if, and in which way, a given expression matches the specified head symbol. -/
meta def match_head_symbol (hs : name) : expr → option head_symbol_match
| (expr.pi _ _ _ t) := match_head_symbol t
| `(%%a ↔ %%b) := if `iff = hs then some ex else
match (match_head_symbol a, match_head_symbol b) with
| (some ex, some ex) :=
some both
| (some ex, _) := some mpr
| (_, some ex) := some mp
| _ := none
end
| (expr.app f _) := match_head_symbol f
| (expr.const n _) := if list.mem hs (unfold_head_symbol n) then some ex else none
| _ := none
meta structure decl_data :=
(d : declaration)
(n : name)
(m : head_symbol_match)
(l : ℕ) -- cached length of name
/--
Generate a `decl_data` from the given declaration if
it matches the head symbol `hs` for the current goal.
-/
-- We used to check here for private declarations, or declarations with certain suffixes.
-- It turns out `apply` is so fast, it's better to just try them all.
meta def process_declaration (hs : name) (d : declaration) : option decl_data :=
let n := d.to_name in
if ¬ d.is_trusted ∨ n.is_internal then
none
else
(λ m, ⟨d, n, m, n.length⟩) <$> match_head_symbol hs d.type
/-- Retrieve all library definitions with a given head symbol. -/
meta def library_defs (hs : name) : tactic (list decl_data) :=
do env ← get_env,
return $ env.decl_filter_map (process_declaration hs)
/--
Apply the lemma `e`, then attempt to close all goals using
`solve_by_elim { discharger := discharger }`, failing if `close_goals = tt`
and there are any goals remaining.
-/
-- Implementation note: as this is used by both `library_search` and `suggest`,
-- we first run `solve_by_elim` separately on a subset of the goals,
-- whether or not `close_goals` is set,
-- and then if `close_goals = tt`, require that `solve_by_elim { all_goals := tt }` succeeds
-- on the remaining goals.
meta def apply_and_solve (close_goals : bool) (discharger : tactic unit) (e : expr) : tactic unit :=
apply e >>
-- Phase 1
-- Run `solve_by_elim` on each "safe" goal separately, not worrying about failures.
-- (We only attempt the "safe" goals in this way in Phase 1. In Phase 2 we will do
-- backtracking search across all goals, allowing us to guess solutions that involve data, or
-- unify metavariables, but only as long as we can finish all goals.)
try (any_goals (independent_goal >> solve_by_elim { discharger := discharger })) >>
-- Phase 2
(done <|>
-- If there were any goals that we did not attempt solving in the first phase
-- (because they weren't propositional, or contained a metavariable)
-- as a second phase we attempt to solve all remaining goals at once
-- (with backtracking across goals).
any_goals (success_if_fail independent_goal) >>
solve_by_elim { backtrack_all_goals := tt, discharger := discharger } <|>
-- and fail unless `close_goals = ff`
guard ¬ close_goals)
/--
Apply the declaration `d` (or the forward and backward implications separately, if it is an `iff`),
and then attempt to solve the goal using `apply_and_solve`.
-/
meta def apply_declaration (close_goals : bool) (discharger : tactic unit) (d : decl_data) :
tactic unit :=
let tac := apply_and_solve close_goals discharger in
do (e, t) ← decl_mk_const d.d,
match d.m with
| ex := tac e
| mp := do l ← iff_mp_core e t, tac l
| mpr := do l ← iff_mpr_core e t, tac l
| both :=
(do l ← iff_mp_core e t, tac l) <|>
(do l ← iff_mpr_core e t, tac l)
end
/--
Replace any metavariables in the expression with underscores, in preparation for printing
`refine ...` statements.
-/
meta def replace_mvars (e : expr) : expr :=
e.replace (λ e' _, if e'.is_mvar then some (unchecked_cast pexpr.mk_placeholder) else none)
/--
Construct a `refine ...` or `exact ...` string which would construct `g`.
-/
meta def tactic_statement (g : expr) : tactic string :=
do g ← instantiate_mvars g,
g ← head_beta g,
r ← pp (replace_mvars g),
if g.has_meta_var
then return (sformat!"Try this: refine {r}")
else return (sformat!"Try this: exact {r}")
/--
Assuming that a goal `g` has been (partially) solved in the tactic_state `l`,
this function prepares a string of the form `exact ...` or `refine ...` (possibly with underscores)
that will reproduce that result.
-/
meta def message (g : expr) (l : tactic_state) : tactic string :=
do s ← read,
write l,
r ← tactic_statement g,
write s,
return r
/-- An `application` records the result of a successful application of a library lemma. -/
meta structure application :=
(state : tactic_state)
(script : string)
(decl : option declaration)
(num_goals : ℕ)
(hyps_used : ℕ)
end suggest
open suggest
declare_trace suggest -- Trace a list of all relevant lemmas
-- implementation note: we produce a `tactic (mllist tactic application)` first,
-- because it's easier to work in the tactic monad, but in a moment we squash this
-- down to an `mllist tactic application`.
private meta def suggest_core' (discharger : tactic unit := done) :
tactic (mllist tactic application) :=
do g :: _ ← get_goals,
hyps ← local_context,
-- Make sure that `solve_by_elim` doesn't just solve the goal immediately:
(lock_tactic_state (do
focus1 $ solve_by_elim { discharger := discharger },
s ← read,
m ← tactic_statement g,
g ← instantiate_mvars g,
return $ mllist.of_list [⟨s, m, none, 0, hyps.countp(λ h, h.occurs g)⟩])) <|>
-- Otherwise, let's actually try applying library lemmas.
(do
-- Collect all definitions with the correct head symbol
t ← infer_type g,
defs ← library_defs (head_symbol t),
-- Sort by length; people like short proofs
let defs := defs.qsort(λ d₁ d₂, d₁.l ≤ d₂.l),
trace_if_enabled `suggest format!"Found {defs.length} relevant lemmas:",
trace_if_enabled `suggest $ defs.map (λ ⟨d, n, m, l⟩, (n, m.to_string)),
-- Try applying each lemma against the goal,
-- then record the number of remaining goals, and number of local hypotheses used.
return $ (mllist.of_list defs).mfilter_map
-- (This tactic block is only executed when we evaluate the mllist,
-- so we need to do the `focus1` here.)
(λ d, lock_tactic_state $ focus1 $ do
apply_declaration ff discharger d,
ng ← num_goals,
g ← instantiate_mvars g,
state ← read,
m ← message g state,
return
{ application .
state := state,
decl := d.d,
script := m,
num_goals := ng,
hyps_used := hyps.countp(λ h, h.occurs g) }))
/--
The core `suggest` tactic.
It attempts to apply a declaration from the library,
then solve new goals using `solve_by_elim`.
It returns a list of `application`s consisting of fields:
* `state`, a tactic state resulting from the successful application of a declaration from
the library,
* `script`, a string of the form `refine ...` or `exact ...` which will reproduce that tactic state,
* `decl`, an `option declaration` indicating the declaration that was applied
(or none, if `solve_by_elim` succeeded),
* `num_goals`, the number of remaining goals, and
* `hyps_used`, the number of local hypotheses used in the solution.
-/
meta def suggest_core (discharger : tactic unit := done) : mllist tactic application :=
(mllist.monad_lift (suggest_core' discharger)).join
/--
See `suggest_core`.
Returns a list of at most `limit` `application`s,
sorted by number of goals, and then (reverse) number of hypotheses used.
-/
meta def suggest (limit : option ℕ := none) (discharger : tactic unit := done) :
tactic (list application) :=
do let results := suggest_core discharger,
-- Get the first n elements of the successful lemmas
L ← if h : limit.is_some then results.take (option.get h) else results.force,
-- Sort by number of remaining goals, then by number of hypotheses used.
return $ L.qsort (λ d₁ d₂, d₁.num_goals < d₂.num_goals ∨
(d₁.num_goals = d₂.num_goals ∧ d₁.hyps_used ≥ d₂.hyps_used))
/--
Returns a list of at most `limit` strings, of the form `exact ...` or `refine ...`, which make
progress on the current goal using a declaration from the library.
-/
meta def suggest_scripts (limit : option ℕ := none) (discharger : tactic unit := done) :
tactic (list string) :=
do L ← suggest limit discharger,
return $ L.map application.script
/--
Returns a string of the form `exact ...`, which closes the current goal.
-/
meta def library_search (discharger : tactic unit := done) : tactic string :=
(suggest_core discharger).mfirst (λ a, do guard (a.num_goals = 0), write a.state, return a.script)
namespace interactive
open tactic
open interactive
open lean.parser
local postfix `?`:9001 := optional
declare_trace silence_suggest -- Turn off `exact/refine ...` trace messages for `suggest`
/--
`suggest` tries to apply suitable theorems/defs from the library, and generates
a list of `exact ...` or `refine ...` scripts that could be used at this step.
It leaves the tactic state unchanged. It is intended as a complement of the search
function in your editor, the `#find` tactic, and `library_search`.
`suggest` takes an optional natural number `num` as input and returns the first `num`
(or less, if all possibilities are exhausted) possibilities ordered by length of lemma names.
The default for `num` is `50`.
For performance reasons `suggest` uses monadic lazy lists (`mllist`). This means that
`suggest` might miss some results if `num` is not large enough. However, because
`suggest` uses monadic lazy lists, smaller values of `num` run faster than larger values.
---
`suggest` lists possible usages of the `refine` tactic and leaves the tactic state unchanged.
It is intended as a complement of the search function in your editor, the `#find` tactic, and
`library_search`.
`suggest` takes an optional natural number `num` as input and returns the first `num` (or less, if
all possibilities are exhausted) possibilities ordered by length of lemma names.
The default for `num` is `50`.
For performance reasons `suggest` uses monadic lazy lists (`mllist`). This means that `suggest`
might miss some results if `num` is not large enough. However, because `suggest` uses monadic
lazy lists, smaller values of `num` run faster than larger values.
An example of `suggest` in action,
```lean
example (n : nat) : n < n + 1 :=
begin suggest, sorry end
```
prints the list,
```lean
Try this: exact nat.lt.base n
Try this: exact nat.lt_succ_self n
Try this: refine not_le.mp _
Try this: refine gt_iff_lt.mp _
Try this: refine nat.lt.step _
Try this: refine lt_of_not_ge _
...
```
-/
meta def suggest (n : parse (with_desc "n" small_nat)?) : tactic unit :=
do L ← tactic.suggest_scripts (n.get_or_else 50),
when (¬ is_trace_enabled_for `silence_suggest)
(if L.length = 0 then
fail "There are no applicable declarations"
else
L.mmap trace >> skip)
add_tactic_doc
{ name := "suggest",
category := doc_category.tactic,
decl_names := [`tactic.interactive.suggest],
tags := ["search", "Try this"] }
declare_trace silence_library_search -- Turn off `exact ...` trace message for `library_search
/--
`library_search` attempts to apply every definition in the library whose head symbol
matches the goal, and then discharge any new goals using `solve_by_elim`.
If it succeeds, it prints a trace message `exact ...` which can replace the invocation
of `library_search`.
---
`library_search` is a tactic to identify existing lemmas in the library. It tries to close the
current goal by applying a lemma from the library, then discharging any new goals using
`solve_by_elim`.
Typical usage is:
```lean
example (n m k : ℕ) : n * (m - k) = n * m - n * k :=
by library_search -- Try this: exact nat.mul_sub_left_distrib n m k
```
`library_search` prints a trace message showing the proof it found, shown above as a comment.
Typically you will then copy and paste this proof, replacing the call to `library_search`.
-/
meta def library_search : tactic unit :=
tactic.library_search tactic.done >>=
if is_trace_enabled_for `silence_library_search then
(λ _, skip)
else
trace
add_tactic_doc
{ name := "library_search",
category := doc_category.tactic,
decl_names := [`tactic.interactive.library_search],
tags := ["search", "Try this"] }
end interactive
/-- Invoking the hole command `library_search` ("Use `library_search` to complete the goal") calls
the tactic `library_search` to produce a proof term with the type of the hole.
Running it on
```lean
example : 0 < 1 :=
{!!}
```
produces
```lean
example : 0 < 1 :=
nat.one_pos
```
-/
@[hole_command] meta def library_search_hole_cmd : hole_command :=
{ name := "library_search",
descr := "Use `library_search` to complete the goal.",
action := λ _, do
script ← library_search,
-- Is there a better API for dropping the 'exact ' prefix on this string?
return [((script.mk_iterator.remove 6).to_string, "by library_search")] }
add_tactic_doc
{ name := "library_search",
category := doc_category.hole_cmd,
decl_names := [`tactic.library_search_hole_cmd],
tags := ["search", "Try this"] }
end tactic
|
604aab1da2f3bfbdcb689fdd54b60b7f67b182fd | 4727251e0cd73359b15b664c3170e5d754078599 | /src/measure_theory/measure/with_density_vector_measure.lean | 711693e33709144fad4b6fce045b3a6528789f79 | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 8,611 | lean | /-
Copyright (c) 2021 Kexing Ying. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kexing Ying
-/
import measure_theory.measure.vector_measure
import measure_theory.function.ae_eq_of_integral
/-!
# Vector measure defined by an integral
Given a measure `μ` and an integrable function `f : α → E`, we can define a vector measure `v` such
that for all measurable set `s`, `v i = ∫ x in s, f x ∂μ`. This definition is useful for
the Radon-Nikodym theorem for signed measures.
## Main definitions
* `measure_theory.measure.with_densityᵥ`: the vector measure formed by integrating a function `f`
with respect to a measure `μ` on some set if `f` is integrable, and `0` otherwise.
-/
noncomputable theory
open_locale classical measure_theory nnreal ennreal
variables {α β : Type*} {m : measurable_space α}
namespace measure_theory
open topological_space
variables {μ ν : measure α}
variables {E : Type*} [normed_group E] [normed_space ℝ E] [complete_space E]
/-- Given a measure `μ` and an integrable function `f`, `μ.with_densityᵥ f` is
the vector measure which maps the set `s` to `∫ₛ f ∂μ`. -/
def measure.with_densityᵥ {m : measurable_space α} (μ : measure α) (f : α → E) :
vector_measure α E :=
if hf : integrable f μ then
{ measure_of' := λ s, if measurable_set s then ∫ x in s, f x ∂μ else 0,
empty' := by simp,
not_measurable' := λ s hs, if_neg hs,
m_Union' := λ s hs₁ hs₂,
begin
convert has_sum_integral_Union hs₁ hs₂ hf.integrable_on,
{ ext n, rw if_pos (hs₁ n) },
{ rw if_pos (measurable_set.Union hs₁) }
end }
else 0
open measure
include m
variables {f g : α → E}
lemma with_densityᵥ_apply (hf : integrable f μ) {s : set α} (hs : measurable_set s) :
μ.with_densityᵥ f s = ∫ x in s, f x ∂μ :=
by { rw [with_densityᵥ, dif_pos hf], exact dif_pos hs }
@[simp] lemma with_densityᵥ_zero : μ.with_densityᵥ (0 : α → E) = 0 :=
by { ext1 s hs, erw [with_densityᵥ_apply (integrable_zero α E μ) hs], simp, }
@[simp] lemma with_densityᵥ_neg : μ.with_densityᵥ (-f) = -μ.with_densityᵥ f :=
begin
by_cases hf : integrable f μ,
{ ext1 i hi,
rw [vector_measure.neg_apply, with_densityᵥ_apply hf hi,
← integral_neg, with_densityᵥ_apply hf.neg hi],
refl },
{ rw [with_densityᵥ, with_densityᵥ, dif_neg hf, dif_neg, neg_zero],
rwa integrable_neg_iff }
end
lemma with_densityᵥ_neg' : μ.with_densityᵥ (λ x, -f x) = -μ.with_densityᵥ f :=
with_densityᵥ_neg
@[simp] lemma with_densityᵥ_add (hf : integrable f μ) (hg : integrable g μ) :
μ.with_densityᵥ (f + g) = μ.with_densityᵥ f + μ.with_densityᵥ g :=
begin
ext1 i hi,
rw [with_densityᵥ_apply (hf.add hg) hi, vector_measure.add_apply,
with_densityᵥ_apply hf hi, with_densityᵥ_apply hg hi],
simp_rw [pi.add_apply],
rw integral_add; rw ← integrable_on_univ,
{ exact hf.integrable_on.restrict measurable_set.univ },
{ exact hg.integrable_on.restrict measurable_set.univ }
end
lemma with_densityᵥ_add' (hf : integrable f μ) (hg : integrable g μ) :
μ.with_densityᵥ (λ x, f x + g x) = μ.with_densityᵥ f + μ.with_densityᵥ g :=
with_densityᵥ_add hf hg
@[simp] lemma with_densityᵥ_sub (hf : integrable f μ) (hg : integrable g μ) :
μ.with_densityᵥ (f - g) = μ.with_densityᵥ f - μ.with_densityᵥ g :=
by rw [sub_eq_add_neg, sub_eq_add_neg, with_densityᵥ_add hf hg.neg, with_densityᵥ_neg]
lemma with_densityᵥ_sub' (hf : integrable f μ) (hg : integrable g μ) :
μ.with_densityᵥ (λ x, f x - g x) = μ.with_densityᵥ f - μ.with_densityᵥ g :=
with_densityᵥ_sub hf hg
@[simp] lemma with_densityᵥ_smul {𝕜 : Type*} [nondiscrete_normed_field 𝕜] [normed_space 𝕜 E]
[smul_comm_class ℝ 𝕜 E] (f : α → E) (r : 𝕜) :
μ.with_densityᵥ (r • f) = r • μ.with_densityᵥ f :=
begin
by_cases hf : integrable f μ,
{ ext1 i hi,
rw [with_densityᵥ_apply (hf.smul r) hi, vector_measure.smul_apply,
with_densityᵥ_apply hf hi, ← integral_smul r f],
refl },
{ by_cases hr : r = 0,
{ rw [hr, zero_smul, zero_smul, with_densityᵥ_zero] },
{ rw [with_densityᵥ, with_densityᵥ, dif_neg hf, dif_neg, smul_zero],
rwa integrable_smul_iff hr f } }
end
lemma with_densityᵥ_smul' {𝕜 : Type*} [nondiscrete_normed_field 𝕜] [normed_space 𝕜 E]
[smul_comm_class ℝ 𝕜 E] (f : α → E) (r : 𝕜) :
μ.with_densityᵥ (λ x, r • f x) = r • μ.with_densityᵥ f :=
with_densityᵥ_smul f r
lemma measure.with_densityᵥ_absolutely_continuous (μ : measure α) (f : α → ℝ) :
μ.with_densityᵥ f ≪ᵥ μ.to_ennreal_vector_measure :=
begin
by_cases hf : integrable f μ,
{ refine vector_measure.absolutely_continuous.mk (λ i hi₁ hi₂, _),
rw to_ennreal_vector_measure_apply_measurable hi₁ at hi₂,
rw [with_densityᵥ_apply hf hi₁, measure.restrict_zero_set hi₂, integral_zero_measure] },
{ rw [with_densityᵥ, dif_neg hf],
exact vector_measure.absolutely_continuous.zero _ }
end
/-- Having the same density implies the underlying functions are equal almost everywhere. -/
lemma integrable.ae_eq_of_with_densityᵥ_eq {f g : α → E} (hf : integrable f μ) (hg : integrable g μ)
(hfg : μ.with_densityᵥ f = μ.with_densityᵥ g) :
f =ᵐ[μ] g :=
begin
refine hf.ae_eq_of_forall_set_integral_eq f g hg (λ i hi _, _),
rw [← with_densityᵥ_apply hf hi, hfg, with_densityᵥ_apply hg hi]
end
lemma with_densityᵥ_eq.congr_ae {f g : α → E} (h : f =ᵐ[μ] g) :
μ.with_densityᵥ f = μ.with_densityᵥ g :=
begin
by_cases hf : integrable f μ,
{ ext i hi,
rw [with_densityᵥ_apply hf hi, with_densityᵥ_apply (hf.congr h) hi],
exact integral_congr_ae (ae_restrict_of_ae h) },
{ have hg : ¬ integrable g μ,
{ intro hg, exact hf (hg.congr h.symm) },
rw [with_densityᵥ, with_densityᵥ, dif_neg hf, dif_neg hg] }
end
lemma integrable.with_densityᵥ_eq_iff {f g : α → E}
(hf : integrable f μ) (hg : integrable g μ) :
μ.with_densityᵥ f = μ.with_densityᵥ g ↔ f =ᵐ[μ] g :=
⟨λ hfg, hf.ae_eq_of_with_densityᵥ_eq hg hfg, λ h, with_densityᵥ_eq.congr_ae h⟩
section signed_measure
lemma with_densityᵥ_to_real {f : α → ℝ≥0∞} (hfm : ae_measurable f μ) (hf : ∫⁻ x, f x ∂μ ≠ ∞) :
μ.with_densityᵥ (λ x, (f x).to_real) =
@to_signed_measure α _ (μ.with_density f) (is_finite_measure_with_density hf) :=
begin
have hfi := integrable_to_real_of_lintegral_ne_top hfm hf,
ext i hi,
rw [with_densityᵥ_apply hfi hi, to_signed_measure_apply_measurable hi,
with_density_apply _ hi, integral_to_real hfm.restrict],
refine ae_lt_top' hfm.restrict (ne_top_of_le_ne_top hf _),
conv_rhs { rw ← set_lintegral_univ },
exact lintegral_mono_set (set.subset_univ _),
end
lemma with_densityᵥ_eq_with_density_pos_part_sub_with_density_neg_part
{f : α → ℝ} (hfi : integrable f μ) :
μ.with_densityᵥ f =
@to_signed_measure α _ (μ.with_density (λ x, ennreal.of_real $ f x))
(is_finite_measure_with_density_of_real hfi.2) -
@to_signed_measure α _ (μ.with_density (λ x, ennreal.of_real $ -f x))
(is_finite_measure_with_density_of_real hfi.neg.2) :=
begin
ext i hi,
rw [with_densityᵥ_apply hfi hi,
integral_eq_lintegral_pos_part_sub_lintegral_neg_part hfi.integrable_on,
vector_measure.sub_apply, to_signed_measure_apply_measurable hi,
to_signed_measure_apply_measurable hi, with_density_apply _ hi, with_density_apply _ hi],
end
lemma integrable.with_densityᵥ_trim_eq_integral {m m0 : measurable_space α}
{μ : measure α} (hm : m ≤ m0) {f : α → ℝ} (hf : integrable f μ)
{i : set α} (hi : measurable_set[m] i) :
(μ.with_densityᵥ f).trim hm i = ∫ x in i, f x ∂μ :=
by rw [vector_measure.trim_measurable_set_eq hm hi, with_densityᵥ_apply hf (hm _ hi)]
lemma integrable.with_densityᵥ_trim_absolutely_continuous
{m m0 : measurable_space α} {μ : measure α} (hm : m ≤ m0) (hfi : integrable f μ) :
(μ.with_densityᵥ f).trim hm ≪ᵥ (μ.trim hm).to_ennreal_vector_measure :=
begin
refine vector_measure.absolutely_continuous.mk (λ j hj₁ hj₂, _),
rw [measure.to_ennreal_vector_measure_apply_measurable hj₁, trim_measurable_set_eq hm hj₁] at hj₂,
rw [vector_measure.trim_measurable_set_eq hm hj₁, with_densityᵥ_apply hfi (hm _ hj₁)],
simp only [measure.restrict_eq_zero.mpr hj₂, integral_zero_measure]
end
end signed_measure
end measure_theory
|
2c528498bd28d31acc271c2c44bdbb5c81cafa98 | 947b78d97130d56365ae2ec264df196ce769371a | /stage0/src/Init/Control/State.lean | 8e025d572333646baa7854a4657b3df81533eb89 | [
"Apache-2.0"
] | permissive | shyamalschandra/lean4 | 27044812be8698f0c79147615b1d5090b9f4b037 | 6e7a883b21eaf62831e8111b251dc9b18f40e604 | refs/heads/master | 1,671,417,126,371 | 1,601,859,995,000 | 1,601,860,020,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 10,123 | lean | /-
Copyright (c) 2016 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura, Sebastian Ullrich
The State monad transformer.
-/
prelude
import Init.Control.Alternative
import Init.Control.MonadControl
import Init.Control.Id
import Init.Control.Except
universes u v w
def StateT (σ : Type u) (m : Type u → Type v) (α : Type u) : Type (max u v) :=
σ → m (α × σ)
@[inline] def StateT.run {σ : Type u} {m : Type u → Type v} {α : Type u} (x : StateT σ m α) (s : σ) : m (α × σ) :=
x s
@[inline] def StateT.run' {σ : Type u} {m : Type u → Type v} [Functor m] {α : Type u} (x : StateT σ m α) (s : σ) : m α :=
Prod.fst <$> x s
@[reducible] def StateM (σ α : Type u) : Type u := StateT σ Id α
instance StateM.subsingleton {σ α} [Subsingleton σ] [Subsingleton α] : Subsingleton (StateM σ α) :=
⟨λ x y => funext $ fun (s : σ) => match x s, y s with
| (a₁, s₁), (a₂, s₂) => Subsingleton.elim a₁ a₂ ▸ Subsingleton.elim s₁ s₂ ▸ rfl⟩
namespace StateT
section
variables {σ : Type u} {m : Type u → Type v}
variables [Monad m] {α β : Type u}
@[inline] protected def pure (a : α) : StateT σ m α :=
fun s => pure (a, s)
@[inline] protected def bind (x : StateT σ m α) (f : α → StateT σ m β) : StateT σ m β :=
fun s => do (a, s) ← x s; f a s
@[inline] protected def map (f : α → β) (x : StateT σ m α) : StateT σ m β :=
fun s => do (a, s) ← x s; pure (f a, s)
instance : Monad (StateT σ m) :=
{ pure := @StateT.pure _ _ _, bind := @StateT.bind _ _ _, map := @StateT.map _ _ _ }
@[inline] protected def orelse [Alternative m] {α : Type u} (x₁ x₂ : StateT σ m α) : StateT σ m α :=
fun s => x₁ s <|> x₂ s
@[inline] protected def failure [Alternative m] {α : Type u} : StateT σ m α :=
fun s => failure
instance [Alternative m] : Alternative (StateT σ m) :=
{ StateT.Monad with
failure := @StateT.failure _ _ _ _,
orelse := @StateT.orelse _ _ _ _ }
@[inline] protected def get : StateT σ m σ :=
fun s => pure (s, s)
@[inline] protected def set : σ → StateT σ m PUnit :=
fun s' s => pure (⟨⟩, s')
@[inline] protected def modifyGet (f : σ → α × σ) : StateT σ m α :=
fun s => pure (f s)
@[inline] protected def lift {α : Type u} (t : m α) : StateT σ m α :=
fun s => do a ← t; pure (a, s)
instance : MonadLift m (StateT σ m) :=
⟨@StateT.lift σ m _⟩
instance (σ m m') [Monad m] [Monad m'] : MonadFunctor m m' (StateT σ m) (StateT σ m') :=
⟨fun _ f x s => f (x s)⟩
@[inline] protected def adapt {σ σ' σ'' α : Type u} {m : Type u → Type v} [Monad m] (split : σ → σ' × σ'')
(join : σ' → σ'' → σ) (x : StateT σ' m α) : StateT σ m α :=
fun st => do
let (st, ctx) := split st;
(a, st') ← x st;
pure (a, join st' ctx)
instance (ε) [MonadExceptOf ε m] : MonadExceptOf ε (StateT σ m) :=
{ throw := fun α => StateT.lift ∘ throwThe ε,
catch := fun α x c s => catchThe ε (x s) (fun e => c e s) }
end
end StateT
/-- An implementation of [MonadState](https://hackage.haskell.org/package/mtl-2.2.2/docs/Control-Monad-State-Class.html).
In contrast to the Haskell implementation, we use overlapping instances to derive instances
automatically from `monadLift`. -/
class MonadStateOf (σ : Type u) (m : Type u → Type v) :=
/- Obtain the top-most State of a Monad stack. -/
(get : m σ)
/- Set the top-most State of a Monad stack. -/
(set : σ → m PUnit)
/- Map the top-most State of a Monad stack.
Note: `modifyGet f` may be preferable to `do s <- get; let (a, s) := f s; put s; pure a`
because the latter does not use the State linearly (without sufficient inlining). -/
(modifyGet {α : Type u} : (σ → α × σ) → m α)
export MonadStateOf (set)
abbrev getThe (σ : Type u) {m : Type u → Type v} [MonadStateOf σ m] : m σ :=
MonadStateOf.get
@[inline] abbrev modifyThe (σ : Type u) {m : Type u → Type v} [MonadStateOf σ m] (f : σ → σ) : m PUnit :=
MonadStateOf.modifyGet fun s => (PUnit.unit, f s)
@[inline] abbrev modifyGetThe {α : Type u} (σ : Type u) {m : Type u → Type v} [MonadStateOf σ m] (f : σ → α × σ) : m α :=
MonadStateOf.modifyGet f
/-- Similar to `MonadStateOf`, but `σ` is an outParam for convenience -/
class MonadState (σ : outParam (Type u)) (m : Type u → Type v) :=
(get : m σ)
(set : σ → m PUnit)
(modifyGet {α : Type u} : (σ → α × σ) → m α)
export MonadState (get modifyGet)
instance monadStateOf.isMonadState (σ : Type u) (m : Type u → Type v) [MonadStateOf σ m] : MonadState σ m :=
{ set := MonadStateOf.set,
get := getThe σ,
modifyGet := fun α f => MonadStateOf.modifyGet f }
section
variables {σ : Type u} {m : Type u → Type v}
@[inline] def modify [MonadState σ m] (f : σ → σ) : m PUnit :=
modifyGet fun s => (PUnit.unit, f s)
@[inline] def getModify [MonadState σ m] [Monad m] (f : σ → σ) : m σ := do
modifyGet fun s => (s, f s)
-- NOTE: The Ordering of the following two instances determines that the top-most `StateT` Monad layer
-- will be picked first
instance monadStateTrans {n : Type u → Type w} [MonadStateOf σ m] [MonadLift m n] : MonadStateOf σ n :=
{ get := monadLift (MonadStateOf.get : m _),
set := fun st => monadLift (MonadStateOf.set st : m _),
modifyGet := fun α f => monadLift (MonadState.modifyGet f : m _) }
instance [Monad m] : MonadStateOf σ (StateT σ m) :=
{ get := StateT.get,
set := StateT.set,
modifyGet := @StateT.modifyGet _ _ _ }
end
/-- Adapt a Monad stack, changing the Type of its top-most State.
This class is comparable to [Control.Lens.Zoom](https://hackage.haskell.org/package/lens-4.15.4/docs/Control-Lens-Zoom.html#t:Zoom), but does not use lenses (yet?), and is derived automatically for any transformer implementing `MonadFunctor`.
For zooming into a part of the State, the `split` Function should split σ into the part σ' and the "context" σ'' so that the potentially modified σ' and the context can be rejoined by `join` in the end.
In the simplest case, the context can be chosen as the full outer State (ie. `σ'' = σ`), which makes `split` and `join` simpler to define. However, note that the State will not be used linearly in this case.
Example:
```
def zoomFst {α σ σ' : Type} : State σ α → State (σ × σ') α :=
adaptState id Prod.mk
```
The Function can also zoom out into a "larger" State, where the new parts are supplied by `split` and discarded by `join` in the end. The State is therefore not used linearly anymore but merely affinely, which is not a practically relevant distinction in Lean.
Example:
```
def withSnd {α σ σ' : Type} (snd : σ') : State (σ × σ') α → State σ α :=
adaptState (fun st => ((st, snd), ())) (fun ⟨st,snd⟩ _ => st)
```
Note: This class can be seen as a simplification of the more "principled" definition
```
class MonadStateFunctor (σ σ' : outParam (Type u)) (n n' : Type u → Type u) :=
(map {α : Type u} : (∀ {m : Type u → Type u} [Monad m], StateT σ m α → StateT σ' m α) → n α → n' α)
```
which better describes the intent of "we can map a `StateT` anywhere in the Monad stack".
If we look at the unfolded Type of the first argument `∀ m [Monad m], (σ → m (α × σ)) → σ' → m (α × σ')`, we see that it has the lens Type `∀ f [Functor f], (α → f α) → β → f β` with `f` specialized to `fun σ => m (α × σ)` (exercise: show that this is a lawful Functor). We can build all lenses we are insterested in from the functions `split` and `join` as
```
fun f _ st => let (st, ctx) := split st in
(fun st' => join st' ctx) <$> f st
```
-/
class MonadStateAdapter (σ σ' : outParam (Type u)) (m m' : Type u → Type v) :=
(adaptState {σ'' α : Type u} (split : σ' → σ × σ'') (join : σ → σ'' → σ') : m α → m' α)
export MonadStateAdapter (adaptState)
section
variables {σ σ' : Type u} {m m' : Type u → Type v}
@[inline] def MonadStateAdapter.adaptState' [MonadStateAdapter σ σ' m m'] {α : Type u} (toSigma : σ' → σ) (fromSigma : σ → σ') : m α → m' α :=
adaptState (fun st => (toSigma st, PUnit.unit)) (fun st _ => fromSigma st)
export MonadStateAdapter (adaptState')
instance monadStateAdapterTrans {n n' : Type u → Type v} [MonadStateAdapter σ σ' m m'] [MonadFunctor m m' n n'] : MonadStateAdapter σ σ' n n' :=
⟨fun σ'' α split join => monadMap (fun α => (adaptState split join : m α → m' α))⟩
instance [Monad m] : MonadStateAdapter σ σ' (StateT σ m) (StateT σ' m) :=
⟨fun σ'' α => StateT.adapt⟩
end
instance (σ : Type u) (m out : Type u → Type v) [MonadRun out m] [Functor m] : MonadRun (fun α => σ → out α) (StateT σ m) :=
⟨fun α x => run ∘ StateT.run' x⟩
class MonadStateRunner (σ : Type u) (m m' : Type u → Type u) :=
(runState {α : Type u} : m α → σ → m' α)
export MonadStateRunner (runState)
section
variables {σ σ' : Type u} {m m' : Type u → Type u}
instance monadStateRunnerTrans {n n' : Type u → Type u} [MonadStateRunner σ m m'] [MonadFunctor m m' n n'] : MonadStateRunner σ n n' :=
⟨fun α x s => monadMap (fun (α) (y : m α) => (runState y s : m' α)) x⟩
instance StateT.MonadStateRunner [Monad m] : MonadStateRunner σ (StateT σ m) m :=
⟨fun α x s => Prod.fst <$> x s⟩
end
instance StateT.monadControl (σ : Type u) (m : Type u → Type v) [Monad m] : MonadControl m (StateT σ m) := {
stM := fun α => α × σ,
liftWith := fun α f => do s ← get; liftM (f (fun β x => x.run s)),
restoreM := fun α x => do (a, s) ← liftM x; set s; pure a
}
instance StateT.finally {m : Type u → Type v} {σ : Type u} [MonadFinally m] [Monad m] : MonadFinally (StateT σ m) :=
{ finally' := fun α β x h s => do
((a, _), (b, s'')) ← finally' (x s)
(fun p? => match p? with
| some (a, s') => h (some a) s'
| none => h none s);
pure ((a, b), s'') }
|
0d5cda31c35555f604e07abde367bdff15b82f26 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/order/omega_complete_partial_order.lean | cbd3fb890ebb2d51a6aff1c0ddea77585233d438 | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 27,644 | lean | /-
Copyright (c) 2020 Simon Hudon. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Simon Hudon
-/
import control.monad.basic
import data.part
import order.hom.order
import tactic.monotonicity
import tactic.wlog
/-!
# Omega Complete Partial Orders
An omega-complete partial order is a partial order with a supremum
operation on increasing sequences indexed by natural numbers (which we
call `ωSup`). In this sense, it is strictly weaker than join complete
semi-lattices as only ω-sized totally ordered sets have a supremum.
The concept of an omega-complete partial order (ωCPO) is useful for the
formalization of the semantics of programming languages. Its notion of
supremum helps define the meaning of recursive procedures.
## Main definitions
* class `omega_complete_partial_order`
* `ite`, `map`, `bind`, `seq` as continuous morphisms
## Instances of `omega_complete_partial_order`
* `part`
* every `complete_lattice`
* pi-types
* product types
* `monotone_hom`
* `continuous_hom` (with notation →𝒄)
* an instance of `omega_complete_partial_order (α →𝒄 β)`
* `continuous_hom.of_fun`
* `continuous_hom.of_mono`
* continuous functions:
* `id`
* `ite`
* `const`
* `part.bind`
* `part.map`
* `part.seq`
## References
* [Chain-complete posets and directed sets with applications][markowsky1976]
* [Recursive definitions of partial functions and their computations][cadiou1972]
* [Semantics of Programming Languages: Structures and Techniques][gunter1992]
-/
universes u v
local attribute [-simp] part.bind_eq_bind part.map_eq_map
open_locale classical
namespace order_hom
variables (α : Type*) (β : Type*) {γ : Type*} {φ : Type*}
variables [preorder α] [preorder β] [preorder γ] [preorder φ]
variables {β γ}
variables {α} {α' : Type*} {β' : Type*} [preorder α'] [preorder β']
/-- `part.bind` as a monotone function -/
@[simps]
def bind {β γ} (f : α →o part β) (g : α →o β → part γ) : α →o part γ :=
{ to_fun := λ x, f x >>= g x,
monotone' :=
begin
intros x y h a,
simp only [and_imp, exists_prop, part.bind_eq_bind, part.mem_bind_iff,
exists_imp_distrib],
intros b hb ha,
refine ⟨b, f.monotone h _ hb, g.monotone h _ _ ha⟩,
end }
end order_hom
namespace omega_complete_partial_order
/-- A chain is a monotone sequence.
See the definition on page 114 of [gunter1992]. -/
def chain (α : Type u) [preorder α] :=
ℕ →o α
namespace chain
variables {α : Type u} {β : Type v} {γ : Type*}
variables [preorder α] [preorder β] [preorder γ]
instance : has_coe_to_fun (chain α) (λ _, ℕ → α) := order_hom.has_coe_to_fun
instance [inhabited α] : inhabited (chain α) :=
⟨ ⟨ λ _, default, λ _ _ _, le_rfl ⟩ ⟩
instance : has_mem α (chain α) :=
⟨λa (c : ℕ →o α), ∃ i, a = c i⟩
variables (c c' : chain α)
variables (f : α →o β)
variables (g : β →o γ)
instance : has_le (chain α) :=
{ le := λ x y, ∀ i, ∃ j, x i ≤ y j }
/-- `map` function for `chain` -/
@[simps {fully_applied := ff}] def map : chain β :=
f.comp c
variables {f}
lemma mem_map (x : α) : x ∈ c → f x ∈ chain.map c f :=
λ ⟨i,h⟩, ⟨i, h.symm ▸ rfl⟩
lemma exists_of_mem_map {b : β} : b ∈ c.map f → ∃ a, a ∈ c ∧ f a = b :=
λ ⟨i,h⟩, ⟨c i, ⟨i, rfl⟩, h.symm⟩
lemma mem_map_iff {b : β} : b ∈ c.map f ↔ ∃ a, a ∈ c ∧ f a = b :=
⟨ exists_of_mem_map _, λ h, by { rcases h with ⟨w,h,h'⟩, subst b, apply mem_map c _ h, } ⟩
@[simp]
lemma map_id : c.map order_hom.id = c :=
order_hom.comp_id _
lemma map_comp : (c.map f).map g = c.map (g.comp f) := rfl
@[mono]
lemma map_le_map {g : α →o β} (h : f ≤ g) : c.map f ≤ c.map g :=
λ i, by simp [mem_map_iff]; intros; existsi i; apply h
/-- `chain.zip` pairs up the elements of two chains that have the same index -/
@[simps]
def zip (c₀ : chain α) (c₁ : chain β) : chain (α × β) :=
order_hom.prod c₀ c₁
end chain
end omega_complete_partial_order
open omega_complete_partial_order
section prio
set_option extends_priority 50
/-- An omega-complete partial order is a partial order with a supremum
operation on increasing sequences indexed by natural numbers (which we
call `ωSup`). In this sense, it is strictly weaker than join complete
semi-lattices as only ω-sized totally ordered sets have a supremum.
See the definition on page 114 of [gunter1992]. -/
class omega_complete_partial_order (α : Type*) extends partial_order α :=
(ωSup : chain α → α)
(le_ωSup : ∀(c:chain α), ∀ i, c i ≤ ωSup c)
(ωSup_le : ∀(c:chain α) x, (∀ i, c i ≤ x) → ωSup c ≤ x)
end prio
namespace omega_complete_partial_order
variables {α : Type u} {β : Type v} {γ : Type*}
variables [omega_complete_partial_order α]
/-- Transfer a `omega_complete_partial_order` on `β` to a `omega_complete_partial_order` on `α`
using a strictly monotone function `f : β →o α`, a definition of ωSup and a proof that `f` is
continuous with regard to the provided `ωSup` and the ωCPO on `α`. -/
@[reducible]
protected def lift [partial_order β] (f : β →o α)
(ωSup₀ : chain β → β)
(h : ∀ x y, f x ≤ f y → x ≤ y)
(h' : ∀ c, f (ωSup₀ c) = ωSup (c.map f)) : omega_complete_partial_order β :=
{ ωSup := ωSup₀,
ωSup_le := λ c x hx, h _ _ (by rw h'; apply ωSup_le; intro; apply f.monotone (hx i)),
le_ωSup := λ c i, h _ _ (by rw h'; apply le_ωSup (c.map f)) }
lemma le_ωSup_of_le {c : chain α} {x : α} (i : ℕ) (h : x ≤ c i) : x ≤ ωSup c :=
le_trans h (le_ωSup c _)
lemma ωSup_total {c : chain α} {x : α} (h : ∀ i, c i ≤ x ∨ x ≤ c i) : ωSup c ≤ x ∨ x ≤ ωSup c :=
classical.by_cases
(assume : ∀ i, c i ≤ x, or.inl (ωSup_le _ _ this))
(assume : ¬ ∀ i, c i ≤ x,
have ∃ i, ¬ c i ≤ x,
by simp only [not_forall] at this ⊢; assumption,
let ⟨i, hx⟩ := this in
have x ≤ c i, from (h i).resolve_left hx,
or.inr $ le_ωSup_of_le _ this)
@[mono]
lemma ωSup_le_ωSup_of_le {c₀ c₁ : chain α} (h : c₀ ≤ c₁) : ωSup c₀ ≤ ωSup c₁ :=
ωSup_le _ _ $
λ i, Exists.rec_on (h i) $
λ j h, le_trans h (le_ωSup _ _)
lemma ωSup_le_iff (c : chain α) (x : α) : ωSup c ≤ x ↔ (∀ i, c i ≤ x) :=
begin
split; intros,
{ transitivity ωSup c,
exact le_ωSup _ _, assumption },
exact ωSup_le _ _ ‹_›,
end
/-- A subset `p : α → Prop` of the type closed under `ωSup` induces an
`omega_complete_partial_order` on the subtype `{a : α // p a}`. -/
def subtype {α : Type*} [omega_complete_partial_order α] (p : α → Prop)
(hp : ∀ (c : chain α), (∀ i ∈ c, p i) → p (ωSup c)) :
omega_complete_partial_order (subtype p) :=
omega_complete_partial_order.lift
(order_hom.subtype.val p)
(λ c, ⟨ωSup _, hp (c.map (order_hom.subtype.val p)) (λ i ⟨n, q⟩, q.symm ▸ (c n).2)⟩)
(λ x y h, h)
(λ c, rfl)
section continuity
open chain
variables [omega_complete_partial_order β]
variables [omega_complete_partial_order γ]
/-- A monotone function `f : α →o β` is continuous if it distributes over ωSup.
In order to distinguish it from the (more commonly used) continuity from topology
(see topology/basic.lean), the present definition is often referred to as
"Scott-continuity" (referring to Dana Scott). It corresponds to continuity
in Scott topological spaces (not defined here). -/
def continuous (f : α →o β) : Prop :=
∀ c : chain α, f (ωSup c) = ωSup (c.map f)
/-- `continuous' f` asserts that `f` is both monotone and continuous. -/
def continuous' (f : α → β) : Prop :=
∃ hf : monotone f, continuous ⟨f, hf⟩
lemma continuous'.to_monotone {f : α → β} (hf : continuous' f) : monotone f := hf.fst
lemma continuous.of_bundled (f : α → β) (hf : monotone f)
(hf' : continuous ⟨f, hf⟩) : continuous' f := ⟨hf, hf'⟩
lemma continuous.of_bundled' (f : α →o β) (hf' : continuous f) : continuous' f :=
⟨f.mono, hf'⟩
lemma continuous'.to_bundled (f : α → β) (hf : continuous' f) :
continuous ⟨f, hf.to_monotone⟩ := hf.snd
@[simp, norm_cast] lemma continuous'_coe : ∀ {f : α →o β}, continuous' f ↔ continuous f
| ⟨f, hf⟩ := ⟨λ ⟨hf', hc⟩, hc, λ hc, ⟨hf, hc⟩⟩
variables (f : α →o β) (g : β →o γ)
lemma continuous_id : continuous (@order_hom.id α _) :=
by intro; rw c.map_id; refl
lemma continuous_comp (hfc : continuous f) (hgc : continuous g) : continuous (g.comp f):=
begin
dsimp [continuous] at *, intro,
rw [hfc,hgc,chain.map_comp]
end
lemma id_continuous' : continuous' (@id α) :=
continuous_id.of_bundled' _
lemma continuous_const (x : β) : continuous (order_hom.const α x) :=
λ c, eq_of_forall_ge_iff $ λ z, by simp [ωSup_le_iff]
lemma const_continuous' (x: β) : continuous' (function.const α x) :=
continuous.of_bundled' (order_hom.const α x) (continuous_const x)
end continuity
end omega_complete_partial_order
namespace part
variables {α : Type u} {β : Type v} {γ : Type*}
open omega_complete_partial_order
lemma eq_of_chain {c : chain (part α)} {a b : α} (ha : some a ∈ c) (hb : some b ∈ c) : a = b :=
begin
cases ha with i ha, replace ha := ha.symm,
cases hb with j hb, replace hb := hb.symm,
wlog h : i ≤ j := le_total i j using [a b i j, b a j i],
rw [eq_some_iff] at ha hb,
have := c.monotone h _ ha, apply mem_unique this hb
end
/-- The (noncomputable) `ωSup` definition for the `ω`-CPO structure on `part α`. -/
protected noncomputable def ωSup (c : chain (part α)) : part α :=
if h : ∃a, some a ∈ c then some (classical.some h) else none
lemma ωSup_eq_some {c : chain (part α)} {a : α} (h : some a ∈ c) : part.ωSup c = some a :=
have ∃a, some a ∈ c, from ⟨a, h⟩,
have a' : some (classical.some this) ∈ c, from classical.some_spec this,
calc part.ωSup c = some (classical.some this) : dif_pos this
... = some a : congr_arg _ (eq_of_chain a' h)
lemma ωSup_eq_none {c : chain (part α)} (h : ¬∃a, some a ∈ c) : part.ωSup c = none :=
dif_neg h
lemma mem_chain_of_mem_ωSup {c : chain (part α)} {a : α} (h : a ∈ part.ωSup c) : some a ∈ c :=
begin
simp [part.ωSup] at h, split_ifs at h,
{ have h' := classical.some_spec h_1,
rw ← eq_some_iff at h, rw ← h, exact h' },
{ rcases h with ⟨ ⟨ ⟩ ⟩ }
end
noncomputable instance omega_complete_partial_order : omega_complete_partial_order (part α) :=
{ ωSup := part.ωSup,
le_ωSup := λ c i, by { intros x hx, rw ← eq_some_iff at hx ⊢,
rw [ωSup_eq_some, ← hx], rw ← hx, exact ⟨i,rfl⟩ },
ωSup_le := by { rintros c x hx a ha, replace ha := mem_chain_of_mem_ωSup ha,
cases ha with i ha, apply hx i, rw ← ha, apply mem_some } }
section inst
lemma mem_ωSup (x : α) (c : chain (part α)) : x ∈ ωSup c ↔ some x ∈ c :=
begin
simp [omega_complete_partial_order.ωSup,part.ωSup],
split,
{ split_ifs, swap, rintro ⟨⟨⟩⟩,
intro h', have hh := classical.some_spec h,
simp at h', subst x, exact hh },
{ intro h,
have h' : ∃ (a : α), some a ∈ c := ⟨_,h⟩,
rw dif_pos h', have hh := classical.some_spec h',
rw eq_of_chain hh h, simp }
end
end inst
end part
namespace pi
variables {α : Type*} {β : α → Type*} {γ : Type*}
open omega_complete_partial_order omega_complete_partial_order.chain
instance [∀a, omega_complete_partial_order (β a)] : omega_complete_partial_order (Πa, β a) :=
{ ωSup := λc a, ωSup (c.map (pi.eval_order_hom a)),
ωSup_le := assume c f hf a, ωSup_le _ _ $ by { rintro i, apply hf },
le_ωSup := assume c i x, le_ωSup_of_le _ $ le_rfl }
namespace omega_complete_partial_order
variables [∀ x, omega_complete_partial_order $ β x]
variables [omega_complete_partial_order γ]
lemma flip₁_continuous'
(f : ∀ x : α, γ → β x) (a : α) (hf : continuous' (λ x y, f y x)) :
continuous' (f a) :=
continuous.of_bundled _
(λ x y h, hf.to_monotone h a)
(λ c, congr_fun (hf.to_bundled _ c) a)
lemma flip₂_continuous'
(f : γ → Π x, β x) (hf : ∀ x, continuous' (λ g, f g x)) : continuous' f :=
continuous.of_bundled _
(λ x y h a, (hf a).to_monotone h)
(by intro c; ext a; apply (hf a).to_bundled _ c)
end omega_complete_partial_order
end pi
namespace prod
open omega_complete_partial_order
variables {α : Type*} {β : Type*} {γ : Type*}
variables [omega_complete_partial_order α]
variables [omega_complete_partial_order β]
variables [omega_complete_partial_order γ]
/-- The supremum of a chain in the product `ω`-CPO. -/
@[simps]
protected def ωSup (c : chain (α × β)) : α × β :=
(ωSup (c.map order_hom.fst), ωSup (c.map order_hom.snd))
@[simps ωSup_fst ωSup_snd]
instance : omega_complete_partial_order (α × β) :=
{ ωSup := prod.ωSup,
ωSup_le := λ c ⟨x,x'⟩ h, ⟨ωSup_le _ _ $ λ i, (h i).1, ωSup_le _ _ $ λ i, (h i).2⟩,
le_ωSup := λ c i,
⟨le_ωSup (c.map order_hom.fst) i, le_ωSup (c.map order_hom.snd) i⟩ }
lemma ωSup_zip (c₀ : chain α) (c₁ : chain β) :
ωSup (c₀.zip c₁) = (ωSup c₀, ωSup c₁) :=
begin
apply eq_of_forall_ge_iff, rintro ⟨z₁,z₂⟩,
simp [ωSup_le_iff, forall_and_distrib],
end
end prod
open omega_complete_partial_order
namespace complete_lattice
variables (α : Type u)
/-- Any complete lattice has an `ω`-CPO structure where the countable supremum is a special case
of arbitrary suprema. -/
@[priority 100] -- see Note [lower instance priority]
instance [complete_lattice α] : omega_complete_partial_order α :=
{ ωSup := λc, ⨆ i, c i,
ωSup_le := λ ⟨c, _⟩ s hs, by simp only [supr_le_iff, order_hom.coe_fun_mk] at ⊢ hs;
intros i; apply hs i,
le_ωSup := assume ⟨c, _⟩ i, by simp only [order_hom.coe_fun_mk]; apply le_supr_of_le i; refl }
variables {α} {β : Type v} [omega_complete_partial_order α] [complete_lattice β]
lemma Sup_continuous (s : set $ α →o β) (hs : ∀ f ∈ s, continuous f) :
continuous (Sup s) :=
begin
intro c, apply eq_of_forall_ge_iff, intro z,
suffices : (∀ (f ∈ s) n, (f : _) (c n) ≤ z) ↔ (∀ n (f ∈ s), (f : _) (c n) ≤ z),
by simpa [ωSup_le_iff, hs _ _ _] { contextual := tt },
exact ⟨λ H n f hf, H f hf n, λ H f hf n, H n f hf⟩
end
lemma supr_continuous {ι : Sort*} {f : ι → α →o β} (h : ∀ i, continuous (f i)) :
continuous (⨆ i, f i) :=
Sup_continuous _ $ set.forall_range_iff.2 h
theorem Sup_continuous' (s : set (α → β)) (hc : ∀ f ∈ s, continuous' f) :
continuous' (Sup s) :=
begin
lift s to set (α →o β) using λ f hf, (hc f hf).to_monotone,
simp only [set.ball_image_iff, continuous'_coe] at hc,
rw [Sup_image],
norm_cast,
exact supr_continuous (λ f, supr_continuous (λ hf, hc f hf)),
end
lemma sup_continuous {f g : α →o β} (hf : continuous f) (hg : continuous g) :
continuous (f ⊔ g) :=
begin
rw ← Sup_pair, apply Sup_continuous,
rintro f (rfl|rfl|_); assumption
end
lemma top_continuous :
continuous (⊤ : α →o β) :=
begin
intro c, apply eq_of_forall_ge_iff, intro z,
simp only [ωSup_le_iff, forall_const, chain.map_coe, (∘), function.const,
order_hom.has_top_top, order_hom.const_coe_coe],
end
lemma bot_continuous :
continuous (⊥ : α →o β) :=
begin
rw ← Sup_empty,
exact Sup_continuous _ (λ f hf, hf.elim),
end
end complete_lattice
namespace complete_lattice
variables {α β : Type*} [omega_complete_partial_order α] [complete_linear_order β]
lemma inf_continuous (f g : α →o β) (hf : continuous f) (hg : continuous g) : continuous (f ⊓ g) :=
begin
refine λ c, eq_of_forall_ge_iff (λ z, _),
simp only [inf_le_iff, hf c, hg c, ωSup_le_iff, ←forall_or_distrib_left, ←forall_or_distrib_right,
function.comp_app, chain.map_coe, order_hom.has_inf_inf_coe],
exact ⟨λ h _, h _ _, λ h i j, (h (max i j)).imp (le_trans $ f.mono $ c.mono $ le_max_left _ _)
(le_trans $ g.mono $ c.mono $ le_max_right _ _)⟩,
end
lemma inf_continuous' {f g : α → β} (hf : continuous' f) (hg : continuous' g) :
continuous' (f ⊓ g) :=
⟨_, inf_continuous _ _ hf.snd hg.snd⟩
end complete_lattice
namespace omega_complete_partial_order
variables {α : Type u} {α' : Type*} {β : Type v} {β' : Type*} {γ : Type*} {φ : Type*}
variables [omega_complete_partial_order α] [omega_complete_partial_order β]
variables [omega_complete_partial_order γ] [omega_complete_partial_order φ]
variables [omega_complete_partial_order α'] [omega_complete_partial_order β']
namespace order_hom
/-- The `ωSup` operator for monotone functions. -/
@[simps]
protected def ωSup (c : chain (α →o β)) : α →o β :=
{ to_fun := λ a, ωSup (c.map (order_hom.apply a)),
monotone' := λ x y h, ωSup_le_ωSup_of_le (chain.map_le_map _ $ λ a, a.monotone h) }
@[simps ωSup_coe]
instance omega_complete_partial_order : omega_complete_partial_order (α →o β) :=
omega_complete_partial_order.lift order_hom.coe_fn_hom order_hom.ωSup
(λ x y h, h) (λ c, rfl)
end order_hom
section
variables (α β)
/-- A monotone function on `ω`-continuous partial orders is said to be continuous
if for every chain `c : chain α`, `f (⊔ i, c i) = ⊔ i, f (c i)`.
This is just the bundled version of `order_hom.continuous`. -/
structure continuous_hom extends order_hom α β :=
(cont : continuous (order_hom.mk to_fun monotone'))
attribute [nolint doc_blame] continuous_hom.to_order_hom
infixr ` →𝒄 `:25 := continuous_hom -- Input: \r\MIc
instance : has_coe_to_fun (α →𝒄 β) (λ _, α → β) := ⟨λ f, f.to_order_hom.to_fun⟩
instance : has_coe (α →𝒄 β) (α →o β) :=
{ coe := continuous_hom.to_order_hom }
instance : partial_order (α →𝒄 β) :=
partial_order.lift (λ f, f.to_order_hom.to_fun) $ by rintro ⟨⟨⟩⟩ ⟨⟨⟩⟩ h; congr; exact h
/-- See Note [custom simps projection]. We need to specify this projection explicitly in this case,
because it is a composition of multiple projections. -/
def continuous_hom.simps.apply (h : α →𝒄 β) : α → β := h
initialize_simps_projections continuous_hom
(to_order_hom_to_fun → apply, -to_order_hom)
end
namespace continuous_hom
theorem congr_fun {f g : α →𝒄 β} (h : f = g) (x : α) : f x = g x :=
congr_arg (λ h : α →𝒄 β, h x) h
theorem congr_arg (f : α →𝒄 β) {x y : α} (h : x = y) : f x = f y :=
congr_arg (λ x : α, f x) h
protected lemma monotone (f : α →𝒄 β) : monotone f := f.monotone'
@[mono] lemma apply_mono {f g : α →𝒄 β} {x y : α} (h₁ : f ≤ g) (h₂ : x ≤ y) : f x ≤ g y :=
order_hom.apply_mono (show (f : α →o β) ≤ g, from h₁) h₂
lemma ite_continuous' {p : Prop} [hp : decidable p] (f g : α → β)
(hf : continuous' f) (hg : continuous' g) : continuous' (λ x, if p then f x else g x) :=
by split_ifs; simp *
lemma ωSup_bind {β γ : Type v} (c : chain α) (f : α →o part β) (g : α →o β → part γ) :
ωSup (c.map (f.bind g)) = ωSup (c.map f) >>= ωSup (c.map g) :=
begin
apply eq_of_forall_ge_iff, intro x,
simp only [ωSup_le_iff, part.bind_le, chain.mem_map_iff, and_imp, order_hom.bind_coe,
exists_imp_distrib],
split; intro h''',
{ intros b hb, apply ωSup_le _ _ _,
rintros i y hy, simp only [part.mem_ωSup] at hb,
rcases hb with ⟨j,hb⟩, replace hb := hb.symm,
simp only [part.eq_some_iff, chain.map_coe, function.comp_app, order_hom.apply_coe]
at hy hb,
replace hb : b ∈ f (c (max i j)) := f.mono (c.mono (le_max_right i j)) _ hb,
replace hy : y ∈ g (c (max i j)) b := g.mono (c.mono (le_max_left i j)) _ _ hy,
apply h''' (max i j),
simp only [exists_prop, part.bind_eq_bind, part.mem_bind_iff, chain.map_coe,
function.comp_app, order_hom.bind_coe],
exact ⟨_,hb,hy⟩, },
{ intros i, intros y hy,
simp only [exists_prop, part.bind_eq_bind, part.mem_bind_iff, chain.map_coe,
function.comp_app, order_hom.bind_coe] at hy,
rcases hy with ⟨b,hb₀,hb₁⟩,
apply h''' b _,
{ apply le_ωSup (c.map g) _ _ _ hb₁ },
{ apply le_ωSup (c.map f) i _ hb₀ } },
end
lemma bind_continuous' {β γ : Type v} (f : α → part β) (g : α → β → part γ) :
continuous' f → continuous' g →
continuous' (λ x, f x >>= g x)
| ⟨hf,hf'⟩ ⟨hg,hg'⟩ :=
continuous.of_bundled' (order_hom.bind ⟨f,hf⟩ ⟨g,hg⟩)
(by intro c; rw [ωSup_bind, ← hf', ← hg']; refl)
lemma map_continuous' {β γ : Type v} (f : β → γ) (g : α → part β)
(hg : continuous' g) :
continuous' (λ x, f <$> g x) :=
by simp only [map_eq_bind_pure_comp];
apply bind_continuous' _ _ hg;
apply const_continuous'
lemma seq_continuous' {β γ : Type v} (f : α → part (β → γ)) (g : α → part β)
(hf : continuous' f) (hg : continuous' g) :
continuous' (λ x, f x <*> g x) :=
by simp only [seq_eq_bind_map];
apply bind_continuous' _ _ hf;
apply pi.omega_complete_partial_order.flip₂_continuous'; intro;
apply map_continuous' _ _ hg
lemma continuous (F : α →𝒄 β) (C : chain α) : F (ωSup C) = ωSup (C.map F) :=
continuous_hom.cont _ _
/-- Construct a continuous function from a bare function, a continuous function, and a proof that
they are equal. -/
@[simps, reducible]
def of_fun (f : α → β) (g : α →𝒄 β) (h : f = g) : α →𝒄 β :=
by refine {to_order_hom := {to_fun := f, ..}, ..}; subst h; rcases g with ⟨⟨⟩⟩; assumption
/-- Construct a continuous function from a monotone function with a proof of continuity. -/
@[simps, reducible]
def of_mono (f : α →o β) (h : ∀ c : chain α, f (ωSup c) = ωSup (c.map f)) : α →𝒄 β :=
{ to_fun := f,
monotone' := f.monotone,
cont := h }
/-- The identity as a continuous function. -/
@[simps]
def id : α →𝒄 α :=
of_mono order_hom.id continuous_id
/-- The composition of continuous functions. -/
@[simps]
def comp (f : β →𝒄 γ) (g : α →𝒄 β) : α →𝒄 γ :=
of_mono (order_hom.comp (↑f) (↑g)) (continuous_comp _ _ g.cont f.cont)
@[ext]
protected lemma ext (f g : α →𝒄 β) (h : ∀ x, f x = g x) : f = g :=
by cases f; cases g; congr; ext; apply h
protected lemma coe_inj (f g : α →𝒄 β) (h : (f : α → β) = g) : f = g :=
continuous_hom.ext _ _ $ _root_.congr_fun h
@[simp]
lemma comp_id (f : β →𝒄 γ) : f.comp id = f := by ext; refl
@[simp]
lemma id_comp (f : β →𝒄 γ) : id.comp f = f := by ext; refl
@[simp]
lemma comp_assoc (f : γ →𝒄 φ) (g : β →𝒄 γ) (h : α →𝒄 β) : f.comp (g.comp h) = (f.comp g).comp h :=
by ext; refl
@[simp]
lemma coe_apply (a : α) (f : α →𝒄 β) : (f : α →o β) a = f a := rfl
/-- `function.const` is a continuous function. -/
def const (x : β) : α →𝒄 β :=
of_mono (order_hom.const _ x) (continuous_const x)
@[simp] theorem const_apply (f : β) (a : α) : const f a = f := rfl
instance [inhabited β] : inhabited (α →𝒄 β) :=
⟨ const default ⟩
/-- The map from continuous functions to monotone functions is itself a monotone function. -/
@[simps]
def to_mono : (α →𝒄 β) →o (α →o β) :=
{ to_fun := λ f, f,
monotone' := λ x y h, h }
/-- When proving that a chain of applications is below a bound `z`, it suffices to consider the
functions and values being selected from the same index in the chains.
This lemma is more specific than necessary, i.e. `c₀` only needs to be a
chain of monotone functions, but it is only used with continuous functions. -/
@[simp]
lemma forall_forall_merge (c₀ : chain (α →𝒄 β)) (c₁ : chain α) (z : β) :
(∀ (i j : ℕ), (c₀ i) (c₁ j) ≤ z) ↔ ∀ (i : ℕ), (c₀ i) (c₁ i) ≤ z :=
begin
split; introv h,
{ apply h },
{ apply le_trans _ (h (max i j)),
transitivity c₀ i (c₁ (max i j)),
{ apply (c₀ i).monotone, apply c₁.monotone, apply le_max_right },
{ apply c₀.monotone, apply le_max_left } }
end
@[simp]
lemma forall_forall_merge' (c₀ : chain (α →𝒄 β)) (c₁ : chain α) (z : β) :
(∀ (j i : ℕ), (c₀ i) (c₁ j) ≤ z) ↔ ∀ (i : ℕ), (c₀ i) (c₁ i) ≤ z :=
by rw [forall_swap,forall_forall_merge]
/-- The `ωSup` operator for continuous functions, which takes the pointwise countable supremum
of the functions in the `ω`-chain. -/
@[simps]
protected def ωSup (c : chain (α →𝒄 β)) : α →𝒄 β :=
continuous_hom.of_mono (ωSup $ c.map to_mono)
begin
intro c',
apply eq_of_forall_ge_iff, intro z,
simp only [ωSup_le_iff, (c _).continuous, chain.map_coe, order_hom.apply_coe,
to_mono_coe, coe_apply, order_hom.omega_complete_partial_order_ωSup_coe,
forall_forall_merge, forall_forall_merge', (∘), function.eval],
end
@[simps ωSup]
instance : omega_complete_partial_order (α →𝒄 β) :=
omega_complete_partial_order.lift continuous_hom.to_mono continuous_hom.ωSup
(λ x y h, h) (λ c, rfl)
namespace prod
/-- The application of continuous functions as a continuous function. -/
@[simps]
def apply : (α →𝒄 β) × α →𝒄 β :=
{ to_fun := λ f, f.1 f.2,
monotone' := λ x y h, by {dsimp, transitivity y.fst x.snd; [apply h.1, apply y.1.monotone h.2]},
cont := begin
intro c,
apply le_antisymm,
{ apply ωSup_le, intros i,
dsimp,
rw (c _).fst.continuous,
apply ωSup_le, intros j,
apply le_ωSup_of_le (max i j),
apply apply_mono,
exact monotone_fst (order_hom.mono _ (le_max_left _ _)),
exact monotone_snd (order_hom.mono _ (le_max_right _ _)), },
{ apply ωSup_le, intros i,
apply le_ωSup_of_le i,
dsimp,
apply order_hom.mono _,
apply le_ωSup_of_le i,
reflexivity, }
end }
end prod
lemma ωSup_def (c : chain (α →𝒄 β)) (x : α) : ωSup c x = continuous_hom.ωSup c x := rfl
lemma ωSup_apply_ωSup (c₀ : chain (α →𝒄 β)) (c₁ : chain α) :
ωSup c₀ (ωSup c₁) = prod.apply (ωSup (c₀.zip c₁)) :=
by simp [prod.apply_apply, prod.ωSup_zip]
/-- A family of continuous functions yields a continuous family of functions. -/
@[simps]
def flip {α : Type*} (f : α → β →𝒄 γ) : β →𝒄 α → γ :=
{ to_fun := λ x y, f y x,
monotone' := λ x y h a, (f a).monotone h,
cont := by intro; ext; change f x _ = _; rw [(f x).continuous ]; refl, }
/-- `part.bind` as a continuous function. -/
@[simps { rhs_md := reducible }]
noncomputable def bind {β γ : Type v}
(f : α →𝒄 part β) (g : α →𝒄 β → part γ) : α →𝒄 part γ :=
of_mono (order_hom.bind (↑f) (↑g)) $ λ c, begin
rw [order_hom.bind, ← order_hom.bind, ωSup_bind, ← f.continuous, ← g.continuous],
refl
end
/-- `part.map` as a continuous function. -/
@[simps {rhs_md := reducible}]
noncomputable def map {β γ : Type v} (f : β → γ) (g : α →𝒄 part β) : α →𝒄 part γ :=
of_fun (λ x, f <$> g x) (bind g (const (pure ∘ f))) $
by ext; simp only [map_eq_bind_pure_comp, bind_apply, order_hom.bind_coe, const_apply,
order_hom.const_coe_coe, coe_apply]
/-- `part.seq` as a continuous function. -/
@[simps {rhs_md := reducible}]
noncomputable def seq {β γ : Type v} (f : α →𝒄 part (β → γ)) (g : α →𝒄 part β) :
α →𝒄 part γ :=
of_fun (λ x, f x <*> g x) (bind f $ (flip $ _root_.flip map g))
(by ext; simp only [seq_eq_bind_map, flip, part.bind_eq_bind, map_apply, part.mem_bind_iff,
bind_apply, order_hom.bind_coe, coe_apply, flip_apply]; refl)
end continuous_hom
end omega_complete_partial_order
|
949fb43a5f45de031d51060bfc3a8b53783b4c1d | dc253be9829b840f15d96d986e0c13520b085033 | /homotopy/three_by_three.hlean | cae70a3b0e2f0dbfe7b07c10f48243b99c146860 | [
"Apache-2.0"
] | permissive | cmu-phil/Spectral | 4ce68e5c1ef2a812ffda5260e9f09f41b85ae0ea | 3b078f5f1de251637decf04bd3fc8aa01930a6b3 | refs/heads/master | 1,685,119,195,535 | 1,684,169,772,000 | 1,684,169,772,000 | 46,450,197 | 42 | 13 | null | 1,505,516,767,000 | 1,447,883,921,000 | Lean | UTF-8 | Lean | false | false | 2,385 | hlean | -- WIP
import ..move_to_lib
open function eq
namespace pushout
section
-- structure span2 : Type :=
-- {A₀₀ A₀₂ A₀₄ A₂₀ A₂₂ A₂₄ A₄₀ A₄₂ A₄₄ : Type}
-- {f₀₁ : A₀₂ → A₀₀} {f₂₁ : A₂₂ → A₂₀} {f₄₁ : A₄₂ → A₄₀}
-- {f₀₃ : A₀₂ → A₀₄} {f₂₃ : A₂₂ → A₂₄} {f₄₃ : A₄₂ → A₄₄}
-- {f₁₀ : A₂₀ → A₀₀} {f₁₂ : A₂₂ → A₀₂} {f₁₄ : A₂₄ → A₀₄}
-- {f₃₀ : A₂₀ → A₄₀} {f₃₂ : A₂₂ → A₄₂} {f₃₄ : A₂₄ → A₄₄}
-- (s₁₁ : f₀₁ ∘ f₁₂ ~ f₁₀ ∘ f₂₁) (s₃₁ : f₄₁ ∘ f₃₂ ~ f₃₀ ∘ f₂₁)
-- (s₁₃ : f₀₃ ∘ f₁₂ ~ f₁₄ ∘ f₂₃) (s₃₃ : f₄₃ ∘ f₃₂ ~ f₃₄ ∘ f₂₃)
structure three_by_three_span : Type :=
{A₀₀ A₂₀ A₄₀ A₀₂ A₂₂ A₄₂ A₀₄ A₂₄ A₄₄ : Type}
{f₁₀ : A₂₀ → A₀₀} {f₃₀ : A₂₀ → A₄₀}
{f₁₂ : A₂₂ → A₀₂} {f₃₂ : A₂₂ → A₄₂}
{f₁₄ : A₂₄ → A₀₄} {f₃₄ : A₂₄ → A₄₄}
{f₀₁ : A₀₂ → A₀₀} {f₀₃ : A₀₂ → A₀₄}
{f₂₁ : A₂₂ → A₂₀} {f₂₃ : A₂₂ → A₂₄}
{f₄₁ : A₄₂ → A₄₀} {f₄₃ : A₄₂ → A₄₄}
(s₁₁ : f₀₁ ∘ f₁₂ ~ f₁₀ ∘ f₂₁) (s₃₁ : f₄₁ ∘ f₃₂ ~ f₃₀ ∘ f₂₁)
(s₁₃ : f₀₃ ∘ f₁₂ ~ f₁₄ ∘ f₂₃) (s₃₃ : f₄₃ ∘ f₃₂ ~ f₃₄ ∘ f₂₃)
open three_by_three_span
variable (E : three_by_three_span)
-- check (pushout.functor (f₂₁ E) (f₀₁ E) (f₄₁ E) (s₁₁ E) (s₃₁ E))
definition pushout2hv (E : three_by_three_span) : Type :=
pushout (pushout.functor (f₂₁ E) (f₀₁ E) (f₄₁ E) (s₁₁ E) (s₃₁ E))
(pushout.functor (f₂₃ E) (f₀₃ E) (f₄₃ E) (s₁₃ E) (s₃₃ E))
definition pushout2vh (E : three_by_three_span) : Type :=
pushout (pushout.functor (f₁₂ E) (f₁₀ E) (f₁₄ E) (s₁₁ E)⁻¹ʰᵗʸ (s₁₃ E)⁻¹ʰᵗʸ)
(pushout.functor (f₃₂ E) (f₃₀ E) (f₃₄ E) (s₃₁ E)⁻¹ʰᵗʸ (s₃₃ E)⁻¹ʰᵗʸ)
definition three_by_three (E : three_by_three_span) : pushout2hv E ≃ pushout2vh E := sorry
end
end pushout
|
db59a65ea54414b6ee695b93e612e346d66d733e | 9028d228ac200bbefe3a711342514dd4e4458bff | /src/algebra/big_operators/pi.lean | 82a05d7127fabe7f0fca044abeb7b8dfe798c7d8 | [
"Apache-2.0"
] | permissive | mcncm/mathlib | 8d25099344d9d2bee62822cb9ed43aa3e09fa05e | fde3d78cadeec5ef827b16ae55664ef115e66f57 | refs/heads/master | 1,672,743,316,277 | 1,602,618,514,000 | 1,602,618,514,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 3,576 | lean | /-
Copyright (c) 2018 Simon Hudon. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Simon Hudon, Patrick Massot
-/
import algebra.ring.pi
import algebra.big_operators.basic
import data.fintype.basic
import algebra.group.prod
/-!
# Big operators for Pi Types
This file contains theorems relevant to big operators in binary and arbitrary product
of monoids and groups
-/
open_locale big_operators
namespace pi
@[to_additive]
lemma list_prod_apply {α : Type*} {β : α → Type*} [∀a, monoid (β a)] (a : α) :
∀ (l : list (Πa, β a)), l.prod a = (l.map (λf:Πa, β a, f a)).prod
| [] := rfl
| (f :: l) := by simp [mul_apply f l.prod a, list_prod_apply l]
@[to_additive]
lemma multiset_prod_apply {α : Type*} {β : α → Type*} [∀a, comm_monoid (β a)] (a : α)
(s : multiset (Πa, β a)) : s.prod a = (s.map (λf:Πa, β a, f a)).prod :=
quotient.induction_on s $ assume l, begin simp [list_prod_apply a l] end
end pi
@[simp, to_additive]
lemma finset.prod_apply {α : Type*} {β : α → Type*} {γ} [∀a, comm_monoid (β a)] (a : α)
(s : finset γ) (g : γ → Πa, β a) : (∏ c in s, g c) a = ∏ c in s, g c a :=
show (s.val.map g).prod a = (s.val.map (λc, g c a)).prod,
by rw [pi.multiset_prod_apply, multiset.map_map]
@[simp, to_additive]
lemma fintype.prod_apply {α : Type*} {β : α → Type*} {γ : Type*} [fintype γ]
[∀a, comm_monoid (β a)] (a : α) (g : γ → Πa, β a) : (∏ c, g c) a = ∏ c, g c a :=
finset.prod_apply a finset.univ g
@[to_additive prod_mk_sum]
lemma prod_mk_prod {α β γ : Type*} [comm_monoid α] [comm_monoid β] (s : finset γ)
(f : γ → α) (g : γ → β) : (∏ x in s, f x, ∏ x in s, g x) = ∏ x in s, (f x, g x) :=
by haveI := classical.dec_eq γ; exact
finset.induction_on s rfl (by simp [prod.ext_iff] {contextual := tt})
section single
variables {I : Type*} [decidable_eq I] {Z : I → Type*}
variables [Π i, add_comm_monoid (Z i)]
-- As we only defined `single` into `add_monoid`, we only prove the `finset.sum` version here.
lemma finset.univ_sum_single [fintype I] (f : Π i, Z i) :
∑ i, pi.single i (f i) = f :=
begin
ext a,
rw [finset.sum_apply, finset.sum_eq_single a],
{ simp, },
{ intros b _ h, simp [h.symm], },
{ intro h, exfalso, simpa using h, },
end
@[ext]
lemma add_monoid_hom.functions_ext [fintype I] (G : Type*)
[add_comm_monoid G] (g h : (Π i, Z i) →+ G)
(w : ∀ (i : I) (x : Z i), g (pi.single i x) = h (pi.single i x)) : g = h :=
begin
ext k,
rw [←finset.univ_sum_single k, add_monoid_hom.map_sum, add_monoid_hom.map_sum],
apply finset.sum_congr rfl,
intros,
apply w,
end
end single
section ring_hom
open pi
variables {I : Type*} [decidable_eq I] {f : I → Type*}
variables [Π i, semiring (f i)]
-- we need `apply`+`convert` because Lean fails to unify different `add_monoid` instances
-- on `Π i, f i`
@[ext]
lemma ring_hom.functions_ext [fintype I] (G : Type*) [semiring G] (g h : (Π i, f i) →+* G)
(w : ∀ (i : I) (x : f i), g (single i x) = h (single i x)) : g = h :=
begin
apply ring_hom.coe_add_monoid_hom_injective,
convert add_monoid_hom.functions_ext _ _ _ _; assumption
end
end ring_hom
namespace prod
variables {α β γ : Type*} [comm_monoid α] [comm_monoid β] {s : finset γ} {f : γ → α × β}
@[to_additive]
lemma fst_prod : (∏ c in s, f c).1 = ∏ c in s, (f c).1 :=
(monoid_hom.fst α β).map_prod f s
@[to_additive]
lemma snd_prod : (∏ c in s, f c).2 = ∏ c in s, (f c).2 :=
(monoid_hom.snd α β).map_prod f s
end prod
|
06066f7930a06181add1dc0e8b2eec22da8e7bb5 | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/order/disjoint.lean | d9e3f8daf84c928be714d739a1de00d134b07cbc | [
"Apache-2.0"
] | permissive | alreadydone/mathlib | dc0be621c6c8208c581f5170a8216c5ba6721927 | c982179ec21091d3e102d8a5d9f5fe06c8fafb73 | refs/heads/master | 1,685,523,275,196 | 1,670,184,141,000 | 1,670,184,141,000 | 287,574,545 | 0 | 0 | Apache-2.0 | 1,670,290,714,000 | 1,597,421,623,000 | Lean | UTF-8 | Lean | false | false | 18,208 | lean | /-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl
-/
import order.bounded_order
/-!
# Disjointness and complements
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> https://github.com/leanprover-community/mathlib4/pull/773
> Any changes to this file require a corresponding PR to mathlib4.
This file defines `disjoint`, `codisjoint`, and the `is_compl` predicate.
## Main declarations
* `disjoint x y`: two elements of a lattice are disjoint if their `inf` is the bottom element.
* `codisjoint x y`: two elements of a lattice are codisjoint if their `join` is the top element.
* `is_compl x y`: In a bounded lattice, predicate for "`x` is a complement of `y`". Note that in a
non distributive lattice, an element can have several complements.
* `complemented_lattice α`: Typeclass stating that any element of a lattice has a complement.
-/
variable {α : Type*}
section disjoint
section partial_order_bot
variables [partial_order α] [order_bot α] {a b c d : α}
/-- Two elements of a lattice are disjoint if their inf is the bottom element.
(This generalizes disjoint sets, viewed as members of the subset lattice.)
Note that we define this without reference to `⊓`, as this allows us to talk about orders where
the infimum is not unique, or where implementing `has_inf` would require additional `decidable`
arguments. -/
def disjoint (a b : α) : Prop := ∀ ⦃x⦄, x ≤ a → x ≤ b → x ≤ ⊥
lemma disjoint.comm : disjoint a b ↔ disjoint b a := forall_congr $ λ _, forall_swap
@[symm] lemma disjoint.symm ⦃a b : α⦄ : disjoint a b → disjoint b a := disjoint.comm.1
lemma symmetric_disjoint : symmetric (disjoint : α → α → Prop) := disjoint.symm
@[simp] lemma disjoint_bot_left : disjoint ⊥ a := λ x hbot ha, hbot
@[simp] lemma disjoint_bot_right : disjoint a ⊥ := λ x ha hbot, hbot
lemma disjoint.mono (h₁ : a ≤ b) (h₂ : c ≤ d) : disjoint b d → disjoint a c :=
λ h x ha hc, h (ha.trans h₁) (hc.trans h₂)
lemma disjoint.mono_left (h : a ≤ b) : disjoint b c → disjoint a c := disjoint.mono h le_rfl
lemma disjoint.mono_right : b ≤ c → disjoint a c → disjoint a b := disjoint.mono le_rfl
@[simp] lemma disjoint_self : disjoint a a ↔ a = ⊥ :=
⟨λ hd, bot_unique $ hd le_rfl le_rfl, λ h x ha hb, ha.trans_eq h⟩
/- TODO: Rename `disjoint.eq_bot` to `disjoint.inf_eq` and `disjoint.eq_bot_of_self` to
`disjoint.eq_bot` -/
alias disjoint_self ↔ disjoint.eq_bot_of_self _
lemma disjoint.ne (ha : a ≠ ⊥) (hab : disjoint a b) : a ≠ b :=
λ h, ha $ disjoint_self.1 $ by rwa ←h at hab
lemma disjoint.eq_bot_of_le (hab : disjoint a b) (h : a ≤ b) : a = ⊥ :=
eq_bot_iff.2 $ hab le_rfl h
lemma disjoint.eq_bot_of_ge (hab : disjoint a b) : b ≤ a → b = ⊥ := hab.symm.eq_bot_of_le
end partial_order_bot
section partial_bounded_order
variables [partial_order α] [bounded_order α] {a : α}
@[simp] theorem disjoint_top : disjoint a ⊤ ↔ a = ⊥ :=
⟨λ h, bot_unique $ h le_rfl le_top, λ h x ha htop, ha.trans_eq h⟩
@[simp] theorem top_disjoint : disjoint ⊤ a ↔ a = ⊥ :=
⟨λ h, bot_unique $ h le_top le_rfl, λ h x htop ha, ha.trans_eq h⟩
end partial_bounded_order
section semilattice_inf_bot
variables [semilattice_inf α] [order_bot α] {a b c d : α}
lemma disjoint_iff_inf_le : disjoint a b ↔ a ⊓ b ≤ ⊥ :=
⟨λ hd, hd inf_le_left inf_le_right, λ h x ha hb, (le_inf ha hb).trans h⟩
lemma disjoint_iff : disjoint a b ↔ a ⊓ b = ⊥ := disjoint_iff_inf_le.trans le_bot_iff
lemma disjoint.le_bot : disjoint a b → a ⊓ b ≤ ⊥ := disjoint_iff_inf_le.mp
lemma disjoint.eq_bot : disjoint a b → a ⊓ b = ⊥ := bot_unique ∘ disjoint.le_bot
lemma disjoint_assoc : disjoint (a ⊓ b) c ↔ disjoint a (b ⊓ c) :=
by rw [disjoint_iff_inf_le, disjoint_iff_inf_le, inf_assoc]
lemma disjoint_left_comm : disjoint a (b ⊓ c) ↔ disjoint b (a ⊓ c) :=
by simp_rw [disjoint_iff_inf_le, inf_left_comm]
lemma disjoint_right_comm : disjoint (a ⊓ b) c ↔ disjoint (a ⊓ c) b :=
by simp_rw [disjoint_iff_inf_le, inf_right_comm]
variables (c)
lemma disjoint.inf_left (h : disjoint a b) : disjoint (a ⊓ c) b := h.mono_left inf_le_left
lemma disjoint.inf_left' (h : disjoint a b) : disjoint (c ⊓ a) b := h.mono_left inf_le_right
lemma disjoint.inf_right (h : disjoint a b) : disjoint a (b ⊓ c) := h.mono_right inf_le_left
lemma disjoint.inf_right' (h : disjoint a b) : disjoint a (c ⊓ b) := h.mono_right inf_le_right
variables {c}
lemma disjoint.of_disjoint_inf_of_le (h : disjoint (a ⊓ b) c) (hle : a ≤ c) : disjoint a b :=
disjoint_iff.2 $ h.eq_bot_of_le $ inf_le_of_left_le hle
lemma disjoint.of_disjoint_inf_of_le' (h : disjoint (a ⊓ b) c) (hle : b ≤ c) : disjoint a b :=
disjoint_iff.2 $ h.eq_bot_of_le $ inf_le_of_right_le hle
end semilattice_inf_bot
section distrib_lattice_bot
variables [distrib_lattice α] [order_bot α] {a b c : α}
@[simp] lemma disjoint_sup_left : disjoint (a ⊔ b) c ↔ disjoint a c ∧ disjoint b c :=
by simp only [disjoint_iff, inf_sup_right, sup_eq_bot_iff]
@[simp] lemma disjoint_sup_right : disjoint a (b ⊔ c) ↔ disjoint a b ∧ disjoint a c :=
by simp only [disjoint_iff, inf_sup_left, sup_eq_bot_iff]
lemma disjoint.sup_left (ha : disjoint a c) (hb : disjoint b c) : disjoint (a ⊔ b) c :=
disjoint_sup_left.2 ⟨ha, hb⟩
lemma disjoint.sup_right (hb : disjoint a b) (hc : disjoint a c) : disjoint a (b ⊔ c) :=
disjoint_sup_right.2 ⟨hb, hc⟩
lemma disjoint.left_le_of_le_sup_right (h : a ≤ b ⊔ c) (hd : disjoint a c) : a ≤ b :=
le_of_inf_le_sup_le (le_trans hd.le_bot bot_le) $ sup_le h le_sup_right
lemma disjoint.left_le_of_le_sup_left (h : a ≤ c ⊔ b) (hd : disjoint a c) : a ≤ b :=
hd.left_le_of_le_sup_right $ by rwa sup_comm
end distrib_lattice_bot
end disjoint
section codisjoint
section partial_order_top
variables [partial_order α] [order_top α] {a b c d : α}
/-- Two elements of a lattice are codisjoint if their sup is the top element.
Note that we define this without reference to `⊔`, as this allows us to talk about orders where
the supremum is not unique, or where implement `has_sup` would require additional `decidable`
arguments. -/
def codisjoint (a b : α) : Prop := ∀ ⦃x⦄, a ≤ x → b ≤ x → ⊤ ≤ x
lemma codisjoint.comm : codisjoint a b ↔ codisjoint b a := forall_congr $ λ _, forall_swap
@[symm] lemma codisjoint.symm ⦃a b : α⦄ : codisjoint a b → codisjoint b a := codisjoint.comm.1
lemma symmetric_codisjoint : symmetric (codisjoint : α → α → Prop) := codisjoint.symm
@[simp] lemma codisjoint_top_left : codisjoint ⊤ a := λ x htop ha, htop
@[simp] lemma codisjoint_top_right : codisjoint a ⊤ := λ x ha htop, htop
lemma codisjoint.mono (h₁ : a ≤ b) (h₂ : c ≤ d) : codisjoint a c → codisjoint b d :=
λ h x ha hc, h (h₁.trans ha) (h₂.trans hc)
lemma codisjoint.mono_left (h : a ≤ b) : codisjoint a c → codisjoint b c :=
codisjoint.mono h le_rfl
lemma codisjoint.mono_right : b ≤ c → codisjoint a b → codisjoint a c :=
codisjoint.mono le_rfl
@[simp] lemma codisjoint_self : codisjoint a a ↔ a = ⊤ :=
⟨λ hd, top_unique $ hd le_rfl le_rfl, λ h x ha hb, h.symm.trans_le ha⟩
/- TODO: Rename `codisjoint.eq_top` to `codisjoint.sup_eq` and `codisjoint.eq_top_of_self` to
`codisjoint.eq_top` -/
alias codisjoint_self ↔ codisjoint.eq_top_of_self _
lemma codisjoint.ne (ha : a ≠ ⊤) (hab : codisjoint a b) : a ≠ b :=
λ h, ha $ codisjoint_self.1 $ by rwa ←h at hab
lemma codisjoint.eq_top_of_le (hab : codisjoint a b) (h : b ≤ a) : a = ⊤ :=
eq_top_iff.2 $ hab le_rfl h
lemma codisjoint.eq_top_of_ge (hab : codisjoint a b) : a ≤ b → b = ⊤ := hab.symm.eq_top_of_le
end partial_order_top
section partial_bounded_order
variables [partial_order α] [bounded_order α] {a : α}
@[simp] theorem codisjoint_bot : codisjoint a ⊥ ↔ a = ⊤ :=
⟨λ h, top_unique $ h le_rfl bot_le, λ h x ha htop, h.symm.trans_le ha⟩
@[simp] theorem bot_codisjoint : codisjoint ⊥ a ↔ a = ⊤ :=
⟨λ h, top_unique $ h bot_le le_rfl, λ h x htop ha, h.symm.trans_le ha⟩
end partial_bounded_order
section semilattice_sup_top
variables [semilattice_sup α] [order_top α] {a b c d : α}
lemma codisjoint_iff_le_sup : codisjoint a b ↔ ⊤ ≤ a ⊔ b := @disjoint_iff_inf_le αᵒᵈ _ _ _ _
lemma codisjoint_iff : codisjoint a b ↔ a ⊔ b = ⊤ := @disjoint_iff αᵒᵈ _ _ _ _
lemma codisjoint.top_le : codisjoint a b → ⊤ ≤ a ⊔ b := @disjoint.le_bot αᵒᵈ _ _ _ _
lemma codisjoint.eq_top : codisjoint a b → a ⊔ b = ⊤ := @disjoint.eq_bot αᵒᵈ _ _ _ _
lemma codisjoint_assoc : codisjoint (a ⊔ b) c ↔ codisjoint a (b ⊔ c) :=
@disjoint_assoc αᵒᵈ _ _ _ _ _
lemma codisjoint_left_comm : codisjoint a (b ⊔ c) ↔ codisjoint b (a ⊔ c) :=
@disjoint_left_comm αᵒᵈ _ _ _ _ _
lemma codisjoint_right_comm : codisjoint (a ⊔ b) c ↔ codisjoint (a ⊔ c) b :=
@disjoint_right_comm αᵒᵈ _ _ _ _ _
variables (c)
lemma codisjoint.sup_left (h : codisjoint a b) : codisjoint (a ⊔ c) b := h.mono_left le_sup_left
lemma codisjoint.sup_left' (h : codisjoint a b) : codisjoint (c ⊔ a) b := h.mono_left le_sup_right
lemma codisjoint.sup_right (h : codisjoint a b) : codisjoint a (b ⊔ c) := h.mono_right le_sup_left
lemma codisjoint.sup_right' (h : codisjoint a b) : codisjoint a (c ⊔ b) := h.mono_right le_sup_right
variables {c}
lemma codisjoint.of_codisjoint_sup_of_le (h : codisjoint (a ⊔ b) c) (hle : c ≤ a) :
codisjoint a b :=
@disjoint.of_disjoint_inf_of_le αᵒᵈ _ _ _ _ _ h hle
lemma codisjoint.of_codisjoint_sup_of_le' (h : codisjoint (a ⊔ b) c) (hle : c ≤ b) :
codisjoint a b :=
@disjoint.of_disjoint_inf_of_le' αᵒᵈ _ _ _ _ _ h hle
end semilattice_sup_top
section distrib_lattice_top
variables [distrib_lattice α] [order_top α] {a b c : α}
@[simp] lemma codisjoint_inf_left : codisjoint (a ⊓ b) c ↔ codisjoint a c ∧ codisjoint b c :=
by simp only [codisjoint_iff, sup_inf_right, inf_eq_top_iff]
@[simp] lemma codisjoint_inf_right : codisjoint a (b ⊓ c) ↔ codisjoint a b ∧ codisjoint a c :=
by simp only [codisjoint_iff, sup_inf_left, inf_eq_top_iff]
lemma codisjoint.inf_left (ha : codisjoint a c) (hb : codisjoint b c) : codisjoint (a ⊓ b) c :=
codisjoint_inf_left.2 ⟨ha, hb⟩
lemma codisjoint.inf_right (hb : codisjoint a b) (hc : codisjoint a c) : codisjoint a (b ⊓ c) :=
codisjoint_inf_right.2 ⟨hb, hc⟩
lemma codisjoint.left_le_of_le_inf_right (h : a ⊓ b ≤ c) (hd : codisjoint b c) : a ≤ c :=
@disjoint.left_le_of_le_sup_right αᵒᵈ _ _ _ _ _ h hd.symm
lemma codisjoint.left_le_of_le_inf_left (h : b ⊓ a ≤ c) (hd : codisjoint b c) : a ≤ c :=
hd.left_le_of_le_inf_right $ by rwa inf_comm
end distrib_lattice_top
end codisjoint
open order_dual
lemma disjoint.dual [semilattice_inf α] [order_bot α] {a b : α} :
disjoint a b → codisjoint (to_dual a) (to_dual b) := id
lemma codisjoint.dual [semilattice_sup α] [order_top α] {a b : α} :
codisjoint a b → disjoint (to_dual a) (to_dual b) := id
@[simp] lemma disjoint_to_dual_iff [semilattice_sup α] [order_top α] {a b : α} :
disjoint (to_dual a) (to_dual b) ↔ codisjoint a b := iff.rfl
@[simp] lemma disjoint_of_dual_iff [semilattice_inf α] [order_bot α] {a b : αᵒᵈ} :
disjoint (of_dual a) (of_dual b) ↔ codisjoint a b := iff.rfl
@[simp] lemma codisjoint_to_dual_iff [semilattice_inf α] [order_bot α] {a b : α} :
codisjoint (to_dual a) (to_dual b) ↔ disjoint a b := iff.rfl
@[simp] lemma codisjoint_of_dual_iff [semilattice_sup α] [order_top α] {a b : αᵒᵈ} :
codisjoint (of_dual a) (of_dual b) ↔ disjoint a b := iff.rfl
section distrib_lattice
variables [distrib_lattice α] [bounded_order α] {a b c : α}
lemma disjoint.le_of_codisjoint (hab : disjoint a b) (hbc : codisjoint b c) : a ≤ c :=
begin
rw [←@inf_top_eq _ _ _ a, ←@bot_sup_eq _ _ _ c, ←hab.eq_bot, ←hbc.eq_top, sup_inf_right],
exact inf_le_inf_right _ le_sup_left,
end
end distrib_lattice
section is_compl
/-- Two elements `x` and `y` are complements of each other if `x ⊔ y = ⊤` and `x ⊓ y = ⊥`. -/
@[protect_proj] structure is_compl [partial_order α] [bounded_order α] (x y : α) : Prop :=
(disjoint : disjoint x y)
(codisjoint : codisjoint x y)
lemma is_compl_iff [partial_order α] [bounded_order α] {a b : α} :
is_compl a b ↔ disjoint a b ∧ codisjoint a b := ⟨λ h, ⟨h.1, h.2⟩, λ h, ⟨h.1, h.2⟩⟩
namespace is_compl
section bounded_partial_order
variables [partial_order α] [bounded_order α] {x y z : α}
@[symm] protected lemma symm (h : is_compl x y) : is_compl y x := ⟨h.1.symm, h.2.symm⟩
lemma dual (h : is_compl x y) : is_compl (to_dual x) (to_dual y) := ⟨h.2, h.1⟩
lemma of_dual {a b : αᵒᵈ} (h : is_compl a b) : is_compl (of_dual a) (of_dual b) := ⟨h.2, h.1⟩
end bounded_partial_order
section bounded_lattice
variables [lattice α] [bounded_order α] {x y z : α}
lemma of_le (h₁ : x ⊓ y ≤ ⊥) (h₂ : ⊤ ≤ x ⊔ y) : is_compl x y :=
⟨disjoint_iff_inf_le.mpr h₁, codisjoint_iff_le_sup.mpr h₂⟩
lemma of_eq (h₁ : x ⊓ y = ⊥) (h₂ : x ⊔ y = ⊤) : is_compl x y :=
⟨disjoint_iff.mpr h₁, codisjoint_iff.mpr h₂⟩
lemma inf_eq_bot (h : is_compl x y) : x ⊓ y = ⊥ := h.disjoint.eq_bot
lemma sup_eq_top (h : is_compl x y) : x ⊔ y = ⊤ := h.codisjoint.eq_top
end bounded_lattice
variables [distrib_lattice α] [bounded_order α] {a b x y z : α}
lemma inf_left_le_of_le_sup_right (h : is_compl x y) (hle : a ≤ b ⊔ y) : a ⊓ x ≤ b :=
calc a ⊓ x ≤ (b ⊔ y) ⊓ x : inf_le_inf hle le_rfl
... = (b ⊓ x) ⊔ (y ⊓ x) : inf_sup_right
... = b ⊓ x : by rw [h.symm.inf_eq_bot, sup_bot_eq]
... ≤ b : inf_le_left
lemma le_sup_right_iff_inf_left_le {a b} (h : is_compl x y) : a ≤ b ⊔ y ↔ a ⊓ x ≤ b :=
⟨h.inf_left_le_of_le_sup_right, h.symm.dual.inf_left_le_of_le_sup_right⟩
lemma inf_left_eq_bot_iff (h : is_compl y z) : x ⊓ y = ⊥ ↔ x ≤ z :=
by rw [← le_bot_iff, ← h.le_sup_right_iff_inf_left_le, bot_sup_eq]
lemma inf_right_eq_bot_iff (h : is_compl y z) : x ⊓ z = ⊥ ↔ x ≤ y :=
h.symm.inf_left_eq_bot_iff
lemma disjoint_left_iff (h : is_compl y z) : disjoint x y ↔ x ≤ z :=
by { rw disjoint_iff, exact h.inf_left_eq_bot_iff }
lemma disjoint_right_iff (h : is_compl y z) : disjoint x z ↔ x ≤ y :=
h.symm.disjoint_left_iff
lemma le_left_iff (h : is_compl x y) : z ≤ x ↔ disjoint z y :=
h.disjoint_right_iff.symm
lemma le_right_iff (h : is_compl x y) : z ≤ y ↔ disjoint z x :=
h.symm.le_left_iff
lemma left_le_iff (h : is_compl x y) : x ≤ z ↔ codisjoint z y := h.dual.le_left_iff
lemma right_le_iff (h : is_compl x y) : y ≤ z ↔ codisjoint z x := h.symm.left_le_iff
protected lemma antitone {x' y'} (h : is_compl x y) (h' : is_compl x' y') (hx : x ≤ x') :
y' ≤ y :=
h'.right_le_iff.2 $ h.symm.codisjoint.mono_right hx
lemma right_unique (hxy : is_compl x y) (hxz : is_compl x z) :
y = z :=
le_antisymm (hxz.antitone hxy $ le_refl x) (hxy.antitone hxz $ le_refl x)
lemma left_unique (hxz : is_compl x z) (hyz : is_compl y z) :
x = y :=
hxz.symm.right_unique hyz.symm
lemma sup_inf {x' y'} (h : is_compl x y) (h' : is_compl x' y') :
is_compl (x ⊔ x') (y ⊓ y') :=
of_eq
(by rw [inf_sup_right, ← inf_assoc, h.inf_eq_bot, bot_inf_eq, bot_sup_eq, inf_left_comm,
h'.inf_eq_bot, inf_bot_eq])
(by rw [sup_inf_left, @sup_comm _ _ x, sup_assoc, h.sup_eq_top, sup_top_eq, top_inf_eq,
sup_assoc, sup_left_comm, h'.sup_eq_top, sup_top_eq])
lemma inf_sup {x' y'} (h : is_compl x y) (h' : is_compl x' y') :
is_compl (x ⊓ x') (y ⊔ y') :=
(h.symm.sup_inf h'.symm).symm
end is_compl
namespace prod
variables {β : Type*} [partial_order α] [partial_order β]
protected lemma disjoint_iff [order_bot α] [order_bot β] {x y : α × β} :
disjoint x y ↔ disjoint x.1 y.1 ∧ disjoint x.2 y.2 :=
begin
split,
{ intros h,
refine ⟨λ a hx hy, (@h (a, ⊥) ⟨hx, _⟩ ⟨hy, _⟩).1, λ b hx hy, (@h (⊥, b) ⟨_, hx⟩ ⟨_, hy⟩).2⟩,
all_goals { exact bot_le }, },
{ rintros ⟨ha, hb⟩ z hza hzb,
refine ⟨ha hza.1 hzb.1, hb hza.2 hzb.2⟩ },
end
protected lemma codisjoint_iff [order_top α] [order_top β] {x y : α × β} :
codisjoint x y ↔ codisjoint x.1 y.1 ∧ codisjoint x.2 y.2 :=
@prod.disjoint_iff αᵒᵈ βᵒᵈ _ _ _ _ _ _
protected lemma is_compl_iff [bounded_order α] [bounded_order β]
{x y : α × β} :
is_compl x y ↔ is_compl x.1 y.1 ∧ is_compl x.2 y.2 :=
by simp_rw [is_compl_iff, prod.disjoint_iff, prod.codisjoint_iff, and_and_and_comm]
end prod
section
variables [lattice α] [bounded_order α] {a b x : α}
@[simp] lemma is_compl_to_dual_iff : is_compl (to_dual a) (to_dual b) ↔ is_compl a b :=
⟨is_compl.of_dual, is_compl.dual⟩
@[simp] lemma is_compl_of_dual_iff {a b : αᵒᵈ} : is_compl (of_dual a) (of_dual b) ↔ is_compl a b :=
⟨is_compl.dual, is_compl.of_dual⟩
lemma is_compl_bot_top : is_compl (⊥ : α) ⊤ := is_compl.of_eq bot_inf_eq sup_top_eq
lemma is_compl_top_bot : is_compl (⊤ : α) ⊥ := is_compl.of_eq inf_bot_eq top_sup_eq
lemma eq_top_of_is_compl_bot (h : is_compl x ⊥) : x = ⊤ := sup_bot_eq.symm.trans h.sup_eq_top
lemma eq_top_of_bot_is_compl (h : is_compl ⊥ x) : x = ⊤ := eq_top_of_is_compl_bot h.symm
lemma eq_bot_of_is_compl_top (h : is_compl x ⊤) : x = ⊥ := eq_top_of_is_compl_bot h.dual
lemma eq_bot_of_top_is_compl (h : is_compl ⊤ x) : x = ⊥ := eq_top_of_bot_is_compl h.dual
end
/-- A complemented bounded lattice is one where every element has a (not necessarily unique)
complement. -/
class complemented_lattice (α) [lattice α] [bounded_order α] : Prop :=
(exists_is_compl : ∀ (a : α), ∃ (b : α), is_compl a b)
export complemented_lattice (exists_is_compl)
namespace complemented_lattice
variables [lattice α] [bounded_order α] [complemented_lattice α]
instance : complemented_lattice αᵒᵈ :=
⟨λ a, let ⟨b, hb⟩ := exists_is_compl (show α, from a) in ⟨b, hb.dual⟩⟩
end complemented_lattice
end is_compl
|
1a301004b58c851a6aa3432c0a2ee284408275fe | 1e561612e7479c100cd9302e3fe08cbd2914aa25 | /mathlib4_experiments/Logic/Basic.lean | 7ce9677084bbf52e2dd13db5507891eb3b971ddf | [
"Apache-2.0"
] | permissive | kbuzzard/mathlib4_experiments | 8de8ed7193f70748a7529e05d831203a7c64eedb | 87cb879b4d602c8ecfd9283b7c0b06015abdbab1 | refs/heads/master | 1,687,971,389,316 | 1,620,336,942,000 | 1,620,336,942,000 | 353,994,588 | 7 | 4 | Apache-2.0 | 1,622,410,748,000 | 1,617,361,732,000 | Lean | UTF-8 | Lean | false | false | 58,476 | lean | /-
Copyright (c) 2016 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Leonardo de Moura
-/
import mathlib4_experiments.Tactic.Split
import mathlib4_experiments.Tactic.Refl
section miscellany
/-- Ex falso, the nondependent eliminator for the `empty` type. -/
def Empty.elim {C : Sort _} (a : Empty) : C := nomatch a
instance : Subsingleton Empty := ⟨λ a => a.elim⟩
/-
## Basic API for prod
-/
theorem Prod.ext_iff : ∀ (p q : α × β),
p = q ↔ p.1 = q.1 ∧ p.2 = q.2
| (p1, p2), (q1, q2) => by
split;
intro h;
rw h;
split;
rfl;
rfl;
skip;
intro ⟨(h1 : p1 = q1), (h2 : p2 = q2)⟩;
rw [h1, h2];
@[simp] theorem eq_iff_true_of_subsingleton [Subsingleton α] (x y : α) :
x = y ↔ True :=
by
split;
simp;
intro _;
apply Subsingleton.elim;
instance Subsingleton.prod {α β : Type _}
[Subsingleton α] [Subsingleton β] :
Subsingleton (α × β) :=
⟨by
intro a b;
cases a;
cases b;
-- todo(yakov) : ext tactic
rw Prod.ext_iff;
split;
allGoals { simp }; ⟩
/-
Kenny term mode version
instance {α : Type u} {β : Type v} [Subsingleton α] [Subsingleton β] : Subsingleton (α × β) :=
⟨λ ⟨a₁, b₁⟩ ⟨a₂, b₂⟩ => congr (congrArg _ $ Subsingleton.elim _ _) (Subsingleton.elim _ _)⟩
-/
instance : DecidableEq Empty := λa => a.elim
instance sort.inhabited : Inhabited (Sort _) := ⟨PUnit⟩
instance sort.inhabited' :
Inhabited (@Inhabited.default (Sort _) _) := ⟨PUnit.unit⟩
instance psum.inhabited_left {α β}
[Inhabited α] : Inhabited (PSum α β) :=
⟨PSum.inl Inhabited.default⟩
instance psum.inhabited_right {α β}
[Inhabited β] : Inhabited (PSum α β) :=
⟨PSum.inr Inhabited.default⟩
instance decidable_eq_of_subsingleton
{α} [Subsingleton α] : DecidableEq α
| a, b => isTrue (Subsingleton.elim a b)
theorem subsingleton_of_forall_eq {α : Sort _}
(x : α) (h : ∀ y, y = x) : Subsingleton α :=
⟨λ a b => (h a).symm ▸ (h b).symm ▸ rfl⟩
theorem subsingleton_iff_forall_eq {α : Sort _} (x : α) :
Subsingleton α ↔ ∀ y, y = x :=
⟨λ h y => @Subsingleton.elim _ h y x, subsingleton_of_forall_eq x⟩
/-!
# I don't understand coercions in Lean 4 so I'm skipping this stuff
-- @[simp] theorem coe_coe {α β γ} [Coe α β] [has_coe_t β γ]
-- (a : α) : (a : γ) = (a : β) := rfl
-- /-- Add an instance to "undo" coercion transitivity into a chain of coercions, because
-- most simp lemmas are stated with respect to simple coercions and will not match when
-- part of a chain. -/
-- @[simp] theorem coe_coe {α β γ} [Coe α β] [has_coe_t β γ]
-- (a : α) : (a : γ) = (a : β) := rfl
-- theorem coe_fn_coe_trans
-- {α β γ} [has_coe α β] [has_coe_t_aux β γ] [has_coe_to_fun γ]
-- (x : α) : @coe_fn α _ x = @coe_fn β _ x := rfl
-- @[simp] theorem coe_fn_coe_base
-- {α β} [has_coe α β] [has_coe_to_fun β]
-- (x : α) : @coe_fn α _ x = @coe_fn β _ x := rfl
-- theorem coe_sort_coe_trans
-- {α β γ} [has_coe α β] [has_coe_t_aux β γ] [has_coe_to_sort γ]
-- (x : α) : @coe_sort α _ x = @coe_sort β _ x := rfl
-- /--
-- Many structures such as bundled morphisms coerce to functions so that you can
-- transparently apply them to arguments. For example, if `e : α ≃ β` and `a : α`
-- then you can write `e a` and this is elaborated as `⇑e a`. This type of
-- coercion is implemented using the `has_coe_to_fun` type class. There is one
-- important consideration:
-- If a type coerces to another type which in turn coerces to a function,
-- then it **must** implement `has_coe_to_fun` directly:
-- ```lean
-- structure sparkling_equiv (α β) extends α ≃ β
-- -- if we add a `has_coe` instance,
-- instance {α β} : has_coe (sparkling_equiv α β) (α ≃ β) :=
-- ⟨sparkling_equiv.to_equiv⟩
-- -- then a `has_coe_to_fun` instance **must** be added as well:
-- instance {α β} : has_coe_to_fun (sparkling_equiv α β) :=
-- ⟨λ _, α → β, λ f, f.to_equiv.to_fun⟩
-- ```
-- (Rationale: if we do not declare the direct coercion, then `⇑e a` is not in
-- simp-normal form. The lemma `coe_fn_coe_base` will unfold it to `⇑↑e a`. This
-- often causes loops in the simplifier.)
-- -/
-- --library_note "function coercion"
-- @[simp] theorem coe_sort_coe_base
-- {α β} [has_coe α β] [has_coe_to_sort β]
-- (x : α) : @coe_sort α _ x = @coe_sort β _ x := rfl
-/
/-- `pempty` is the universe-polymorphic analogue of `empty`. -/
--@[derive decidable_eq]
inductive PEmpty : Type u
/-- Ex falso, the nondependent eliminator for the `pempty` type. -/
def PEmpty.elim {C : Sort v} : PEmpty → C :=
λ a => nomatch a
instance subsingleton_pempty : Subsingleton PEmpty := ⟨λ a => a.elim⟩
@[simp] theorem not_nonempty_pempty : ¬ Nonempty PEmpty :=
λ ⟨h⟩ => h.elim
@[simp] theorem forall_pempty {P : PEmpty → Prop} :
(∀ x : PEmpty, P x) ↔ True :=
⟨λ _ => trivial, λ _ x => x.elim⟩
@[simp] theorem exists_pempty {P : PEmpty → Prop} :
(∃ x : PEmpty, P x) ↔ False :=
⟨λ ⟨x, _⟩ => x.elim, False.elim⟩
-- TODO -- find out how to do this using equation compiler
theorem congr_arg_heq {α} {β : α → Sort u} (f : ∀ a, β a) :
∀ {a₁ a₂ : α}, a₁ = a₂ → f a₁ ≅ f a₂
| _, _, (Eq.refl _) => HEq.rfl
-- this will work when I switch to nightly, apparently?
macro "lemma" n:declId sig:declSig val:declVal : command => `(theorem $n $sig $val)
theorem plift.down_inj {α : Sort u} : ∀ (a b : PLift α), a.down = b.down → a = b
| ⟨_⟩, ⟨_⟩, (Eq.refl _) => rfl
-- don't know analogue in Lean 4
-- attribute [symm] ne.symm
lemma ne_comm {α} {a b : α} : a ≠ b ↔ b ≠ a := ⟨Ne.symm, Ne.symm⟩
@[simp] theorem eq_iff_eq_cancel_left {b c : α} :
(∀ {a}, a = b ↔ a = c) ↔ (b = c) :=
⟨λ h => by rw [← h], λ h a => by rw h; refl⟩
@[simp] theorem eq_iff_eq_cancel_right {a b : α} :
(∀ {c}, a = c ↔ b = c) ↔ (a = b) :=
⟨λ h => by rw h, λ h a => by rw h; refl⟩
/-- Wrapper for adding elementary propositions to the type class systems.
Warning: this can easily be abused. See the rest of this docstring for details.
Certain propositions should not be treated as a class globally,
but sometimes it is very convenient to be able to use the type class system
in specific circumstances.
For example, `zmod p` is a field if and only if `p` is a prime number.
In order to be able to find this field instance automatically by type class search,
we have to turn `p.prime` into an instance implicit assumption.
On the other hand, making `nat.prime` a class would require a major refactoring of the library,
and it is questionable whether making `nat.prime` a class is desirable at all.
The compromise is to add the assumption `[fact p.prime]` to `zmod.field`.
In particular, this class is not intended for turning the type class system
into an automated theorem prover for first order logic. -/
class fact (p : Prop) : Prop := (out' : p)
def fact.out (p : Prop) [c : fact p] : p := fact.out'
lemma fact.elim {p : Prop} (h : fact p) : p := h.1
lemma fact_iff {p : Prop} : fact p ↔ p := ⟨λ h => h.1, λ h => ⟨h⟩⟩
end miscellany
/-!
### Declarations about propositional connectives
-/
theorem false_ne_true : False ≠ True
| h => h.symm ▸ trivial
section propositional
variable {a b c d : Prop}
/-! ### Declarations about `implies` -/
-- instance : is_refl Prop iff := ⟨iff.refl⟩
-- instance : IsTrans Prop iff := ⟨λ _ _ _ => iff.trans⟩
theorem iff_of_eq (e : a = b) : a ↔ b := e ▸ Iff.rfl
theorem iff_iff_eq : (a ↔ b) ↔ a = b := ⟨propext, iff_of_eq⟩
@[simp] theorem eq_iff_iff {p q : Prop} : (p = q) ↔ (p ↔ q) := iff_iff_eq.symm
-- can't find in Lean 4
theorem iff_true_intro {P : Prop} : P → (P ↔ True) :=
λ h => ⟨λ _=> trivial, λ _ => h⟩
@[simp] theorem imp_self : (a → a) ↔ True := iff_true_intro id
theorem imp_intro {α β : Prop} (h : α) : β → α := λ _ => h
theorem imp_false : (a → False) ↔ ¬ a := Iff.rfl
theorem imp_and_distrib {α} : (α → b ∧ c) ↔ (α → b) ∧ (α → c) :=
⟨λ h => ⟨λ ha => (h ha).left, λ ha => (h ha).right⟩,
λ h ha => ⟨h.left ha, h.right ha⟩⟩
@[simp] theorem and_imp : (a ∧ b → c) ↔ (a → b → c) :=
Iff.intro (λ h ha hb => h ⟨ha, hb⟩) (λ h ⟨ha, hb⟩ => h ha hb)
theorem iff_def {a b : Prop} : (a ↔ b) ↔ (a → b) ∧ (b → a) :=
⟨λ ⟨h1, h2⟩ => ⟨h1, h2⟩, λ ⟨h1, h2⟩ => ⟨h1, h2⟩⟩
theorem And.comm {P Q : Prop} : P ∧ Q ↔ Q ∧ P :=
⟨λ ⟨h1, h2⟩ => ⟨h2, h1⟩, λ ⟨h1, h2⟩ => ⟨h2, h1⟩⟩
theorem iff_def' : (a ↔ b) ↔ (b → a) ∧ (a → b) :=
iff_def.trans And.comm
theorem imp_true_iff {α : Sort u} : (α → True) ↔ True :=
iff_true_intro $ λ _ => trivial
theorem imp_iff_right (ha : a) : (a → b) ↔ b :=
⟨λ f => f ha, imp_intro⟩
/-! ### Declarations about `not` -/
/-- Ex falso for negation. From `¬ a` and `a` anything follows. This is the same as `absurd` with
the arguments flipped, but it is in the `not` namespace so that projection notation can be used. -/
def not.elim {α : Sort u} (H1 : ¬a) (H2 : a) : α := absurd H2 H1
@[reducible] theorem not.imp {a b : Prop} (H2 : ¬b) (H1 : a → b) : ¬a := mt H1 H2
theorem not_not_of_not_imp : ¬(a → b) → ¬¬a :=
mt not.elim
theorem not_of_not_imp {a : Prop} : ¬(a → b) → ¬b :=
mt imp_intro
theorem dec_em (p : Prop) [Decidable p] : p ∨ ¬p := Decidable.em p
theorem em (p : Prop) : p ∨ ¬ p := Classical.em _
theorem or_not {p : Prop} : p ∨ ¬ p := em _
/- all propositions are Decidable -/
noncomputable local instance (priority := low) propDecidable (a : Prop) : Decidable a :=
Classical.choice <| match em a with
| Or.inl h => ⟨isTrue h⟩
| Or.inr h => ⟨isFalse h⟩
theorem by_contradiction {p} : (¬p → False) → p := Decidable.byContradiction
-- alias by_contradiction ← by_contra
theorem by_contra {p} : (¬p → False) → p := Decidable.byContradiction
/-
In most of mathlib, we use the law of excluded middle (LEM) and the axiom of choice (AC) freely.
The `decidable` namespace contains versions of lemmas from the root namespace that explicitly
attempt to avoid the axiom of choice, usually by adding decidability assumptions on the inputs.
You can check if a lemma uses the axiom of choice by using `#print axioms foo` and seeing if
`classical.choice` appears in the list.
-/
--library_note "decidable namespace"
/-
As mathlib is primarily classical,
if the type signature of a `def` or `lemma` does not require any `decidable` instances to state,
it is preferable not to introduce any `decidable` instances that are needed in the proof
as arguments, but rather to use the `classical` tactic as needed.
In the other direction, when `decidable` instances do appear in the type signature,
it is better to use explicitly introduced ones rather than allowing Lean to automatically infer
classical ones, as these may cause instance mismatch errors later.
-/
--library_note "decidable arguments"
lemma not_not_intro {P : Prop} : P → ¬ ¬ P := λ hp h => h hp
-- See Note [decidable namespace]
protected theorem decidable.not_not [Decidable a] : ¬¬a ↔ a :=
Iff.intro Decidable.byContradiction not_not_intro
/-- The Double Negation Theorem: `¬ ¬ P` is equivalent to `P`.
The left-to-right direction, double negation elimination (DNE),
is classically true but not constructively. -/
@[simp] theorem not_not : ¬¬a ↔ a := decidable.not_not
theorem of_not_not : ¬¬a → a := by_contra
-- See Note [decidable namespace]
protected theorem decidable.of_not_imp [Decidable a] (h : ¬ (a → b)) : a :=
Decidable.byContradiction (not_not_of_not_imp h)
theorem of_not_imp : ¬ (a → b) → a := decidable.of_not_imp
-- See Note [decidable namespace]
protected theorem decidable.not_imp_symm [Decidable a] (h : ¬a → b) (hb : ¬b) : a :=
Decidable.byContradiction $ hb ∘ h
theorem not.decidable_imp_symm [Decidable a] : (¬a → b) → ¬b → a := decidable.not_imp_symm
theorem not.imp_symm : (¬a → b) → ¬b → a := not.decidable_imp_symm
-- See Note [decidable namespace]
protected theorem decidable.not_imp_comm [Decidable a] [Decidable b] : (¬a → b) ↔ (¬b → a) :=
⟨not.decidable_imp_symm, not.decidable_imp_symm⟩
theorem not_imp_comm : (¬a → b) ↔ (¬b → a) := decidable.not_imp_comm
@[simp] theorem imp_not_self : (a → ¬a) ↔ ¬a := ⟨λ h ha => h ha ha, λ h _ => h⟩
theorem decidable.not_imp_self [Decidable a] : (¬a → a) ↔ a := by
have this := @imp_not_self (¬a);
rw decidable.not_not at this;
assumption;
@[simp] theorem not_imp_self : (¬a → a) ↔ a := decidable.not_imp_self
theorem imp.swap : (a → b → c) ↔ (b → a → c) :=
⟨flip, flip⟩
theorem imp_not_comm : (a → ¬b) ↔ (b → ¬a) :=
imp.swap
/-! ### Declarations about `and` -/
theorem and_congr_right (h : a → (b ↔ c)) : a ∧ b ↔ a ∧ c :=
⟨λ ⟨ha, hb⟩ => ⟨ha, (h ha).1 hb⟩ , λ ⟨ha, hc⟩ => ⟨ha, (h ha).2 hc⟩⟩
theorem and_congr_left (h : c → (a ↔ b)) : a ∧ c ↔ b ∧ c :=
And.comm.trans $ (and_congr_right h).trans And.comm
lemma and_congr {a b c d : Prop} : (a ↔ c) → (b ↔ d) → (a ∧ b ↔ c ∧ d) :=
λ ⟨hac, hca⟩ ⟨hbd, hdb⟩ =>
⟨λ ⟨ha, hb⟩ => ⟨hac ha, hbd hb⟩, λ ⟨hc, hd⟩ => ⟨hca hc, hdb hd⟩⟩
theorem and_congr_left' (h : a ↔ b) : a ∧ c ↔ b ∧ c := and_congr h Iff.rfl
theorem and_congr_right' (h : b ↔ c) : a ∧ b ↔ a ∧ c := and_congr Iff.rfl h
theorem not_and_of_not_left (b : Prop) : ¬a → ¬(a ∧ b) :=
mt And.left
theorem not_and_of_not_right (a : Prop) {b : Prop} : ¬b → ¬(a ∧ b) :=
mt And.right
theorem and.imp {a b c d : Prop} : (a → c) → (b → d) → a ∧ b → c ∧ d :=
λ hac hbd ⟨ha, hb⟩ => ⟨hac ha, hbd hb⟩
theorem and.imp_left (h : a → b) : a ∧ c → b ∧ c :=
and.imp h id
theorem and.imp_right (h : a → b) : c ∧ a → c ∧ b :=
and.imp id h
-- and.left_comm : ∀ {a b c : Prop}, a ∧ b ∧ c ↔ b ∧ a ∧ c
theorem and.left_comm {a b c : Prop} : a ∧ b ∧ c ↔ b ∧ a ∧ c :=
⟨λ ⟨ha, hb, hc⟩ => ⟨hb, ha, hc⟩, λ ⟨hb, ha, hc⟩ => ⟨ha, hb, hc⟩⟩
@[simp] theorem Iff_self {p : Prop} : (p ↔ p) ↔ True :=
⟨λ _ => trivial, λ _ => Iff.rfl⟩
lemma and.right_comm : (a ∧ b) ∧ c ↔ (a ∧ c) ∧ b :=
by simp only [and.left_comm, And.comm, Iff_self]
lemma and.rotate : a ∧ b ∧ c ↔ b ∧ c ∧ a :=
by simp only [and.left_comm, And.comm, Iff_self]
theorem and_not_self_iff (a : Prop) : a ∧ ¬ a ↔ False :=
⟨λ h => (h.right) (h.left), (λ h => h.elim)⟩
theorem not_and_self_iff (a : Prop) : ¬ a ∧ a ↔ False :=
Iff.intro (λ ⟨hna, ha⟩ => hna ha) False.elim
theorem and_iff_left_of_imp {a b : Prop} (h : a → b) : (a ∧ b) ↔ a :=
Iff.intro And.left (λ ha => ⟨ha, h ha⟩)
theorem and_iff_right_of_imp {a b : Prop} (h : b → a) : (a ∧ b) ↔ b :=
Iff.intro And.right (λ hb => ⟨h hb, hb⟩)
@[simp] theorem and_iff_left_iff_imp {a b : Prop} : ((a ∧ b) ↔ a) ↔ (a → b) :=
⟨λ h ha => (h.2 ha).2, and_iff_left_of_imp⟩
@[simp] theorem and_iff_right_iff_imp {a b : Prop} : ((a ∧ b) ↔ b) ↔ (b → a) :=
⟨λ h ha => (h.2 ha).1, and_iff_right_of_imp⟩
@[simp] theorem and.congr_right_iff : (a ∧ b ↔ a ∧ c) ↔ (a → (b ↔ c)) :=
⟨λ h ha => by simp [ha] at h; exact h, and_congr_right⟩
/-
TO_BE_PORTED
#check @and.congr_right_iff
example : ∀ {a b c : Prop}, a ∧ b ↔ a ∧ c ↔ a → (b ↔ c) := sorry
example : ∀ {a b c : Prop}, a ↔ a ↔ a := sorry
@[simp] theorem and.congr_left_iff : (a ∧ c ↔ b ∧ c) ↔ c → (a ↔ b) :=
by simp only [And.comm, ← and.congr_right_iff]
@[simp] lemma and_self_left : a ∧ a ∧ b ↔ a ∧ b :=
⟨λ h, ⟨h.1, h.2.2⟩, λ h, ⟨h.1, h.1, h.2⟩⟩
@[simp] lemma and_self_right : (a ∧ b) ∧ b ↔ a ∧ b :=
⟨λ h, ⟨h.1.1, h.2⟩, λ h, ⟨⟨h.1, h.2⟩, h.2⟩⟩
/-! ### Declarations about `or` -/
theorem or_congr_left (h : a ↔ b) : a ∨ c ↔ b ∨ c := or_congr h iff.rfl
theorem or_congr_right (h : b ↔ c) : a ∨ b ↔ a ∨ c := or_congr iff.rfl h
theorem or.right_comm : (a ∨ b) ∨ c ↔ (a ∨ c) ∨ b := by rw [or_assoc, or_assoc, or_comm b]
theorem or_of_or_of_imp_of_imp (h₁ : a ∨ b) (h₂ : a → c) (h₃ : b → d) : c ∨ d :=
or.imp h₂ h₃ h₁
theorem or_of_or_of_imp_left (h₁ : a ∨ c) (h : a → b) : b ∨ c :=
or.imp_left h h₁
theorem or_of_or_of_imp_right (h₁ : c ∨ a) (h : a → b) : c ∨ b :=
or.imp_right h h₁
theorem or.elim3 (h : a ∨ b ∨ c) (ha : a → d) (hb : b → d) (hc : c → d) : d :=
or.elim h ha (assume h₂, or.elim h₂ hb hc)
theorem or_imp_distrib : (a ∨ b → c) ↔ (a → c) ∧ (b → c) :=
⟨assume h, ⟨assume ha, h (or.inl ha), assume hb, h (or.inr hb)⟩,
assume ⟨ha, hb⟩, or.rec ha hb⟩
-- See Note [decidable namespace]
protected theorem decidable.or_iff_not_imp_left [decidable a] : a ∨ b ↔ (¬ a → b) :=
⟨or.resolve_left, λ h, dite _ or.inl (or.inr ∘ h)⟩
theorem or_iff_not_imp_left : a ∨ b ↔ (¬ a → b) := decidable.or_iff_not_imp_left
-- See Note [decidable namespace]
protected theorem decidable.or_iff_not_imp_right [decidable b] : a ∨ b ↔ (¬ b → a) :=
or.comm.trans decidable.or_iff_not_imp_left
theorem or_iff_not_imp_right : a ∨ b ↔ (¬ b → a) := decidable.or_iff_not_imp_right
-- See Note [decidable namespace]
protected theorem decidable.not_imp_not [decidable a] : (¬ a → ¬ b) ↔ (b → a) :=
⟨assume h hb, decidable.by_contradiction $ assume na, h na hb, mt⟩
theorem not_imp_not : (¬ a → ¬ b) ↔ (b → a) := decidable.not_imp_not
@[simp] theorem or_iff_left_iff_imp : (a ∨ b ↔ a) ↔ (b → a) :=
⟨λ h hb, h.1 (or.inr hb), or_iff_left_of_imp⟩
@[simp] theorem or_iff_right_iff_imp : (a ∨ b ↔ b) ↔ (a → b) :=
by rw [or_comm, or_iff_left_iff_imp]
/-! ### Declarations about distributivity -/
/-- `∧` distributes over `∨` (on the left). -/
theorem and_or_distrib_left : a ∧ (b ∨ c) ↔ (a ∧ b) ∨ (a ∧ c) :=
⟨λ ⟨ha, hbc⟩, hbc.imp (and.intro ha) (and.intro ha),
or.rec (and.imp_right or.inl) (and.imp_right or.inr)⟩
/-- `∧` distributes over `∨` (on the right). -/
theorem or_and_distrib_right : (a ∨ b) ∧ c ↔ (a ∧ c) ∨ (b ∧ c) :=
(and.comm.trans and_or_distrib_left).trans (or_congr and.comm and.comm)
/-- `∨` distributes over `∧` (on the left). -/
theorem or_and_distrib_left : a ∨ (b ∧ c) ↔ (a ∨ b) ∧ (a ∨ c) :=
⟨or.rec (λha, and.intro (or.inl ha) (or.inl ha)) (and.imp or.inr or.inr),
and.rec $ or.rec (imp_intro ∘ or.inl) (or.imp_right ∘ and.intro)⟩
/-- `∨` distributes over `∧` (on the right). -/
theorem and_or_distrib_right : (a ∧ b) ∨ c ↔ (a ∨ c) ∧ (b ∨ c) :=
(or.comm.trans or_and_distrib_left).trans (and_congr or.comm or.comm)
@[simp] lemma or_self_left : a ∨ a ∨ b ↔ a ∨ b :=
⟨λ h, h.elim or.inl id, λ h, h.elim or.inl (or.inr ∘ or.inr)⟩
@[simp] lemma or_self_right : (a ∨ b) ∨ b ↔ a ∨ b :=
⟨λ h, h.elim id or.inr, λ h, h.elim (or.inl ∘ or.inl) or.inr⟩
/-! Declarations about `iff` -/
theorem iff_of_true (ha : a) (hb : b) : a ↔ b :=
⟨λ_, hb, λ _, ha⟩
theorem iff_of_false (ha : ¬a) (hb : ¬b) : a ↔ b :=
⟨ha.elim, hb.elim⟩
theorem iff_true_left (ha : a) : (a ↔ b) ↔ b :=
⟨λ h, h.1 ha, iff_of_true ha⟩
theorem iff_true_right (ha : a) : (b ↔ a) ↔ b :=
iff.comm.trans (iff_true_left ha)
theorem iff_false_left (ha : ¬a) : (a ↔ b) ↔ ¬b :=
⟨λ h, mt h.2 ha, iff_of_false ha⟩
theorem iff_false_right (ha : ¬a) : (b ↔ a) ↔ ¬b :=
iff.comm.trans (iff_false_left ha)
@[simp]
lemma iff_mpr_iff_true_intro {P : Prop} (h : P) : iff.mpr (iff_true_intro h) true.intro = h := rfl
-- See Note [decidable namespace]
protected theorem decidable.not_or_of_imp [decidable a] (h : a → b) : ¬ a ∨ b :=
if ha : a then or.inr (h ha) else or.inl ha
theorem not_or_of_imp : (a → b) → ¬ a ∨ b := decidable.not_or_of_imp
-- See Note [decidable namespace]
protected theorem decidable.imp_iff_not_or [decidable a] : (a → b) ↔ (¬ a ∨ b) :=
⟨decidable.not_or_of_imp, or.neg_resolve_left⟩
theorem imp_iff_not_or : (a → b) ↔ (¬ a ∨ b) := decidable.imp_iff_not_or
-- See Note [decidable namespace]
protected theorem decidable.imp_or_distrib [decidable a] : (a → b ∨ c) ↔ (a → b) ∨ (a → c) :=
by simp [decidable.imp_iff_not_or, or.comm, or.left_comm]
theorem imp_or_distrib : (a → b ∨ c) ↔ (a → b) ∨ (a → c) := decidable.imp_or_distrib
-- See Note [decidable namespace]
protected theorem decidable.imp_or_distrib' [decidable b] : (a → b ∨ c) ↔ (a → b) ∨ (a → c) :=
by by_cases b; simp [h, or_iff_right_of_imp ((∘) false.elim)]
theorem imp_or_distrib' : (a → b ∨ c) ↔ (a → b) ∨ (a → c) := decidable.imp_or_distrib'
theorem not_imp_of_and_not : a ∧ ¬ b → ¬ (a → b)
| ⟨ha, hb⟩ h := hb $ h ha
-- See Note [decidable namespace]
protected theorem decidable.not_imp [decidable a] : ¬(a → b) ↔ a ∧ ¬b :=
⟨λ h, ⟨decidable.of_not_imp h, not_of_not_imp h⟩, not_imp_of_and_not⟩
theorem not_imp : ¬(a → b) ↔ a ∧ ¬b := decidable.not_imp
-- for monotonicity
lemma imp_imp_imp (h₀ : c → a) (h₁ : b → d) : (a → b) → (c → d) :=
assume (h₂ : a → b), h₁ ∘ h₂ ∘ h₀
-- See Note [decidable namespace]
protected theorem decidable.peirce (a b : Prop) [decidable a] : ((a → b) → a) → a :=
if ha : a then λ h, ha else λ h, h ha.elim
theorem peirce (a b : Prop) : ((a → b) → a) → a := decidable.peirce _ _
theorem peirce' {a : Prop} (H : ∀ b : Prop, (a → b) → a) : a := H _ id
-- See Note [decidable namespace]
protected theorem decidable.not_iff_not [decidable a] [decidable b] : (¬ a ↔ ¬ b) ↔ (a ↔ b) :=
by rw [@iff_def (¬ a), @iff_def' a]; exact and_congr decidable.not_imp_not decidable.not_imp_not
theorem not_iff_not : (¬ a ↔ ¬ b) ↔ (a ↔ b) := decidable.not_iff_not
-- See Note [decidable namespace]
protected theorem decidable.not_iff_comm [decidable a] [decidable b] : (¬ a ↔ b) ↔ (¬ b ↔ a) :=
by rw [@iff_def (¬ a), @iff_def (¬ b)]; exact and_congr decidable.not_imp_comm imp_not_comm
theorem not_iff_comm : (¬ a ↔ b) ↔ (¬ b ↔ a) := decidable.not_iff_comm
-- See Note [decidable namespace]
protected theorem decidable.not_iff : ∀ [decidable b], ¬ (a ↔ b) ↔ (¬ a ↔ b) :=
by intro h; cases h; simp only [h, iff_true, iff_false]
theorem not_iff : ¬ (a ↔ b) ↔ (¬ a ↔ b) := decidable.not_iff
-- See Note [decidable namespace]
protected theorem decidable.iff_not_comm [decidable a] [decidable b] : (a ↔ ¬ b) ↔ (b ↔ ¬ a) :=
by rw [@iff_def a, @iff_def b]; exact and_congr imp_not_comm decidable.not_imp_comm
theorem iff_not_comm : (a ↔ ¬ b) ↔ (b ↔ ¬ a) := decidable.iff_not_comm
-- See Note [decidable namespace]
protected theorem decidable.iff_iff_and_or_not_and_not [decidable b] :
(a ↔ b) ↔ (a ∧ b) ∨ (¬ a ∧ ¬ b) :=
by { split; intro h,
{ rw h; by_cases b; [left,right]; split; assumption },
{ cases h with h h; cases h; split; intro; { contradiction <|> assumption } } }
theorem iff_iff_and_or_not_and_not : (a ↔ b) ↔ (a ∧ b) ∨ (¬ a ∧ ¬ b) :=
decidable.iff_iff_and_or_not_and_not
lemma decidable.iff_iff_not_or_and_or_not [decidable a] [decidable b] :
(a ↔ b) ↔ ((¬a ∨ b) ∧ (a ∨ ¬b)) :=
begin
rw [iff_iff_implies_and_implies a b],
simp only [decidable.imp_iff_not_or, or.comm]
end
lemma iff_iff_not_or_and_or_not : (a ↔ b) ↔ ((¬a ∨ b) ∧ (a ∨ ¬b)) :=
decidable.iff_iff_not_or_and_or_not
-- See Note [decidable namespace]
protected theorem decidable.not_and_not_right [decidable b] : ¬(a ∧ ¬b) ↔ (a → b) :=
⟨λ h ha, h.decidable_imp_symm $ and.intro ha, λ h ⟨ha, hb⟩, hb $ h ha⟩
theorem not_and_not_right : ¬(a ∧ ¬b) ↔ (a → b) := decidable.not_and_not_right
/-- Transfer decidability of `a` to decidability of `b`, if the propositions are equivalent.
**Important**: this function should be used instead of `rw` on `decidable b`, because the
kernel will get stuck reducing the usage of `propext` otherwise,
and `dec_trivial` will not work. -/
@[inline] def decidable_of_iff (a : Prop) (h : a ↔ b) [D : decidable a] : decidable b :=
decidable_of_decidable_of_iff D h
/-- Transfer decidability of `b` to decidability of `a`, if the propositions are equivalent.
This is the same as `decidable_of_iff` but the iff is flipped. -/
@[inline] def decidable_of_iff' (b : Prop) (h : a ↔ b) [D : decidable b] : decidable a :=
decidable_of_decidable_of_iff D h.symm
/-- Prove that `a` is decidable by constructing a boolean `b` and a proof that `b ↔ a`.
(This is sometimes taken as an alternate definition of decidability.) -/
def decidable_of_bool : ∀ (b : bool) (h : b ↔ a), decidable a
| tt h := is_true (h.1 rfl)
| ff h := is_false (mt h.2 bool.ff_ne_tt)
/-! ### De Morgan's laws -/
theorem not_and_of_not_or_not (h : ¬ a ∨ ¬ b) : ¬ (a ∧ b)
| ⟨ha, hb⟩ := or.elim h (absurd ha) (absurd hb)
-- See Note [decidable namespace]
protected theorem decidable.not_and_distrib [decidable a] : ¬ (a ∧ b) ↔ ¬a ∨ ¬b :=
⟨λ h, if ha : a then or.inr (λ hb, h ⟨ha, hb⟩) else or.inl ha, not_and_of_not_or_not⟩
-- See Note [decidable namespace]
protected theorem decidable.not_and_distrib' [decidable b] : ¬ (a ∧ b) ↔ ¬a ∨ ¬b :=
⟨λ h, if hb : b then or.inl (λ ha, h ⟨ha, hb⟩) else or.inr hb, not_and_of_not_or_not⟩
/-- One of de Morgan's laws: the negation of a conjunction is logically equivalent to the
disjunction of the negations. -/
theorem not_and_distrib : ¬ (a ∧ b) ↔ ¬a ∨ ¬b := decidable.not_and_distrib
@[simp] theorem not_and : ¬ (a ∧ b) ↔ (a → ¬ b) := and_imp
theorem not_and' : ¬ (a ∧ b) ↔ b → ¬a :=
not_and.trans imp_not_comm
/-- One of de Morgan's laws: the negation of a disjunction is logically equivalent to the
conjunction of the negations. -/
theorem not_or_distrib : ¬ (a ∨ b) ↔ ¬ a ∧ ¬ b :=
⟨λ h, ⟨λ ha, h (or.inl ha), λ hb, h (or.inr hb)⟩,
λ ⟨h₁, h₂⟩ h, or.elim h h₁ h₂⟩
-- See Note [decidable namespace]
protected theorem decidable.or_iff_not_and_not [decidable a] [decidable b] : a ∨ b ↔ ¬ (¬a ∧ ¬b) :=
by rw [← not_or_distrib, decidable.not_not]
theorem or_iff_not_and_not : a ∨ b ↔ ¬ (¬a ∧ ¬b) := decidable.or_iff_not_and_not
-- See Note [decidable namespace]
protected theorem decidable.and_iff_not_or_not [decidable a] [decidable b] :
a ∧ b ↔ ¬ (¬ a ∨ ¬ b) :=
by rw [← decidable.not_and_distrib, decidable.not_not]
theorem and_iff_not_or_not : a ∧ b ↔ ¬ (¬ a ∨ ¬ b) := decidable.and_iff_not_or_not
end propositional
/-! ### Declarations about equality -/
section equality
variables {α : Sort*} {a b : α}
@[simp] theorem heq_iff_eq : a == b ↔ a = b :=
⟨eq_of_heq, heq_of_eq⟩
theorem proof_irrel_heq {p q : Prop} (hp : p) (hq : q) : hp == hq :=
have p = q, from propext ⟨λ _, hq, λ _, hp⟩,
by subst q; refl
theorem ne_of_mem_of_not_mem {α β} [has_mem α β] {s : β} {a b : α}
(h : a ∈ s) : b ∉ s → a ≠ b :=
mt $ λ e, e ▸ h
lemma ne_of_apply_ne {α β : Sort*} (f : α → β) {x y : α} (h : f x ≠ f y) : x ≠ y :=
λ (w : x = y), h (congr_arg f w)
theorem eq_equivalence : equivalence (@eq α) :=
⟨eq.refl, @eq.symm _, @eq.trans _⟩
/-- Transport through trivial families is the identity. -/
@[simp]
lemma eq_rec_constant {α : Sort*} {a a' : α} {β : Sort*} (y : β) (h : a = a') :
(@eq.rec α a (λ a, β) y a' h) = y :=
by { cases h, refl, }
@[simp]
lemma eq_mp_eq_cast {α β : Sort*} (h : α = β) : eq.mp h = cast h := rfl
@[simp]
lemma eq_mpr_eq_cast {α β : Sort*} (h : α = β) : eq.mpr h = cast h.symm := rfl
@[simp]
lemma cast_cast : ∀ {α β γ : Sort*} (ha : α = β) (hb : β = γ) (a : α),
cast hb (cast ha a) = cast (ha.trans hb) a
| _ _ _ rfl rfl a := rfl
@[simp] lemma congr_refl_left {α β : Sort*} (f : α → β) {a b : α} (h : a = b) :
congr (eq.refl f) h = congr_arg f h :=
rfl
@[simp] lemma congr_refl_right {α β : Sort*} {f g : α → β} (h : f = g) (a : α) :
congr h (eq.refl a) = congr_fun h a :=
rfl
@[simp] lemma congr_arg_refl {α β : Sort*} (f : α → β) (a : α) :
congr_arg f (eq.refl a) = eq.refl (f a) :=
rfl
@[simp] lemma congr_fun_rfl {α β : Sort*} (f : α → β) (a : α) :
congr_fun (eq.refl f) a = eq.refl (f a) :=
rfl
@[simp] lemma congr_fun_congr_arg {α β γ : Sort*} (f : α → β → γ) {a a' : α} (p : a = a') (b : β) :
congr_fun (congr_arg f p) b = congr_arg (λ a, f a b) p :=
rfl
lemma heq_of_cast_eq :
∀ {α β : Sort*} {a : α} {a' : β} (e : α = β) (h₂ : cast e a = a'), a == a'
| α ._ a a' rfl h := eq.rec_on h (heq.refl _)
lemma rec_heq_of_heq {β} {C : α → Sort*} {x : C a} {y : β} (eq : a = b) (h : x == y) :
@eq.rec α a C x b eq == y :=
by subst eq; exact h
protected lemma eq.congr {x₁ x₂ y₁ y₂ : α} (h₁ : x₁ = y₁) (h₂ : x₂ = y₂) :
(x₁ = x₂) ↔ (y₁ = y₂) :=
by { subst h₁, subst h₂ }
lemma eq.congr_left {x y z : α} (h : x = y) : x = z ↔ y = z := by rw [h]
lemma eq.congr_right {x y z : α} (h : x = y) : z = x ↔ z = y := by rw [h]
lemma congr_arg2 {α β γ : Type*} (f : α → β → γ) {x x' : α} {y y' : β}
(hx : x = x') (hy : y = y') : f x y = f x' y' :=
by { subst hx, subst hy }
end equality
/-! ### Declarations about quantifiers -/
section quantifiers
variables {α : Sort*} {β : Sort*} {p q : α → Prop} {b : Prop}
lemma forall_imp (h : ∀ a, p a → q a) : (∀ a, p a) → ∀ a, q a :=
λ h' a, h a (h' a)
lemma forall₂_congr {p q : α → β → Prop} (h : ∀ a b, p a b ↔ q a b) :
(∀ a b, p a b) ↔ (∀ a b, q a b) :=
forall_congr (λ a, forall_congr (h a))
lemma forall₃_congr {γ : Sort*} {p q : α → β → γ → Prop}
(h : ∀ a b c, p a b c ↔ q a b c) :
(∀ a b c, p a b c) ↔ (∀ a b c, q a b c) :=
forall_congr (λ a, forall₂_congr (h a))
lemma forall₄_congr {γ δ : Sort*} {p q : α → β → γ → δ → Prop}
(h : ∀ a b c d, p a b c d ↔ q a b c d) :
(∀ a b c d, p a b c d) ↔ (∀ a b c d, q a b c d) :=
forall_congr (λ a, forall₃_congr (h a))
lemma Exists.imp (h : ∀ a, (p a → q a)) (p : ∃ a, p a) : ∃ a, q a := exists_imp_exists h p
lemma exists_imp_exists' {p : α → Prop} {q : β → Prop} (f : α → β) (hpq : ∀ a, p a → q (f a))
(hp : ∃ a, p a) : ∃ b, q b :=
exists.elim hp (λ a hp', ⟨_, hpq _ hp'⟩)
lemma exists₂_congr {p q : α → β → Prop} (h : ∀ a b, p a b ↔ q a b) :
(∃ a b, p a b) ↔ (∃ a b, q a b) :=
exists_congr (λ a, exists_congr (h a))
lemma exists₃_congr {γ : Sort*} {p q : α → β → γ → Prop}
(h : ∀ a b c, p a b c ↔ q a b c) :
(∃ a b c, p a b c) ↔ (∃ a b c, q a b c) :=
exists_congr (λ a, exists₂_congr (h a))
lemma exists₄_congr {γ δ : Sort*} {p q : α → β → γ → δ → Prop}
(h : ∀ a b c d, p a b c d ↔ q a b c d) :
(∃ a b c d, p a b c d) ↔ (∃ a b c d, q a b c d) :=
exists_congr (λ a, exists₃_congr (h a))
theorem forall_swap {p : α → β → Prop} : (∀ x y, p x y) ↔ ∀ y x, p x y :=
⟨function.swap, function.swap⟩
theorem exists_swap {p : α → β → Prop} : (∃ x y, p x y) ↔ ∃ y x, p x y :=
⟨λ ⟨x, y, h⟩, ⟨y, x, h⟩, λ ⟨y, x, h⟩, ⟨x, y, h⟩⟩
@[simp] theorem exists_imp_distrib : ((∃ x, p x) → b) ↔ ∀ x, p x → b :=
⟨λ h x hpx, h ⟨x, hpx⟩, λ h ⟨x, hpx⟩, h x hpx⟩
/--
Extract an element from a existential statement, using `classical.some`.
-/
-- This enables projection notation.
@[reducible] noncomputable def Exists.some {p : α → Prop} (P : ∃ a, p a) : α := classical.some P
/--
Show that an element extracted from `P : ∃ a, p a` using `P.some` satisfies `p`.
-/
lemma Exists.some_spec {p : α → Prop} (P : ∃ a, p a) : p (P.some) := classical.some_spec P
--theorem forall_not_of_not_exists (h : ¬ ∃ x, p x) : ∀ x, ¬ p x :=
--forall_imp_of_exists_imp h
theorem not_exists_of_forall_not (h : ∀ x, ¬ p x) : ¬ ∃ x, p x :=
exists_imp_distrib.2 h
@[simp] theorem not_exists : (¬ ∃ x, p x) ↔ ∀ x, ¬ p x :=
exists_imp_distrib
theorem not_forall_of_exists_not : (∃ x, ¬ p x) → ¬ ∀ x, p x
| ⟨x, hn⟩ h := hn (h x)
-- See Note [decidable namespace]
protected theorem decidable.not_forall {p : α → Prop}
[decidable (∃ x, ¬ p x)] [∀ x, decidable (p x)] : (¬ ∀ x, p x) ↔ ∃ x, ¬ p x :=
⟨not.decidable_imp_symm $ λ nx x, nx.decidable_imp_symm $ λ h, ⟨x, h⟩,
not_forall_of_exists_not⟩
@[simp] theorem not_forall {p : α → Prop} : (¬ ∀ x, p x) ↔ ∃ x, ¬ p x := decidable.not_forall
-- See Note [decidable namespace]
protected theorem decidable.not_forall_not [decidable (∃ x, p x)] :
(¬ ∀ x, ¬ p x) ↔ ∃ x, p x :=
(@decidable.not_iff_comm _ _ _ (decidable_of_iff (¬ ∃ x, p x) not_exists)).1 not_exists
theorem not_forall_not : (¬ ∀ x, ¬ p x) ↔ ∃ x, p x := decidable.not_forall_not
-- See Note [decidable namespace]
protected theorem decidable.not_exists_not [∀ x, decidable (p x)] : (¬ ∃ x, ¬ p x) ↔ ∀ x, p x :=
by simp [decidable.not_not]
@[simp] theorem not_exists_not : (¬ ∃ x, ¬ p x) ↔ ∀ x, p x := decidable.not_exists_not
-- TODO: duplicate of a lemma in core
theorem forall_true_iff : (α → true) ↔ true :=
implies_true_iff α
-- Unfortunately this causes simp to loop sometimes, so we
-- add the 2 and 3 cases as simp lemmas instead
theorem forall_true_iff' (h : ∀ a, p a ↔ true) : (∀ a, p a) ↔ true :=
iff_true_intro (λ _, of_iff_true (h _))
@[simp] theorem forall_2_true_iff {β : α → Sort*} : (∀ a, β a → true) ↔ true :=
forall_true_iff' $ λ _, forall_true_iff
@[simp] theorem forall_3_true_iff {β : α → Sort*} {γ : Π a, β a → Sort*} :
(∀ a (b : β a), γ a b → true) ↔ true :=
forall_true_iff' $ λ _, forall_2_true_iff
@[simp] theorem forall_const (α : Sort*) [i : nonempty α] : (α → b) ↔ b :=
⟨i.elim, λ hb x, hb⟩
@[simp] theorem exists_const (α : Sort*) [i : nonempty α] : (∃ x : α, b) ↔ b :=
⟨λ ⟨x, h⟩, h, i.elim exists.intro⟩
theorem forall_and_distrib : (∀ x, p x ∧ q x) ↔ (∀ x, p x) ∧ (∀ x, q x) :=
⟨λ h, ⟨λ x, (h x).left, λ x, (h x).right⟩, λ ⟨h₁, h₂⟩ x, ⟨h₁ x, h₂ x⟩⟩
theorem exists_or_distrib : (∃ x, p x ∨ q x) ↔ (∃ x, p x) ∨ (∃ x, q x) :=
⟨λ ⟨x, hpq⟩, hpq.elim (λ hpx, or.inl ⟨x, hpx⟩) (λ hqx, or.inr ⟨x, hqx⟩),
λ hepq, hepq.elim (λ ⟨x, hpx⟩, ⟨x, or.inl hpx⟩) (λ ⟨x, hqx⟩, ⟨x, or.inr hqx⟩)⟩
@[simp] theorem exists_and_distrib_left {q : Prop} {p : α → Prop} :
(∃x, q ∧ p x) ↔ q ∧ (∃x, p x) :=
⟨λ ⟨x, hq, hp⟩, ⟨hq, x, hp⟩, λ ⟨hq, x, hp⟩, ⟨x, hq, hp⟩⟩
@[simp] theorem exists_and_distrib_right {q : Prop} {p : α → Prop} :
(∃x, p x ∧ q) ↔ (∃x, p x) ∧ q :=
by simp [and_comm]
@[simp] theorem forall_eq {a' : α} : (∀a, a = a' → p a) ↔ p a' :=
⟨λ h, h a' rfl, λ h a e, e.symm ▸ h⟩
@[simp] theorem forall_eq' {a' : α} : (∀a, a' = a → p a) ↔ p a' :=
by simp [@eq_comm _ a']
-- this lemma is needed to simplify the output of `list.mem_cons_iff`
@[simp] theorem forall_eq_or_imp {a' : α} : (∀ a, a = a' ∨ q a → p a) ↔ p a' ∧ ∀ a, q a → p a :=
by simp only [or_imp_distrib, forall_and_distrib, forall_eq]
@[simp] theorem exists_eq {a' : α} : ∃ a, a = a' := ⟨_, rfl⟩
@[simp] theorem exists_eq' {a' : α} : ∃ a, a' = a := ⟨_, rfl⟩
@[simp] theorem exists_eq_left {a' : α} : (∃ a, a = a' ∧ p a) ↔ p a' :=
⟨λ ⟨a, e, h⟩, e ▸ h, λ h, ⟨_, rfl, h⟩⟩
@[simp] theorem exists_eq_right {a' : α} : (∃ a, p a ∧ a = a') ↔ p a' :=
(exists_congr $ by exact λ a, and.comm).trans exists_eq_left
@[simp] theorem exists_eq_right_right {a' : α} :
(∃ (a : α), p a ∧ b ∧ a = a') ↔ p a' ∧ b :=
⟨λ ⟨_, hp, hq, rfl⟩, ⟨hp, hq⟩, λ ⟨hp, hq⟩, ⟨a', hp, hq, rfl⟩⟩
@[simp] theorem exists_eq_right_right' {a' : α} :
(∃ (a : α), p a ∧ b ∧ a' = a) ↔ p a' ∧ b :=
⟨λ ⟨_, hp, hq, rfl⟩, ⟨hp, hq⟩, λ ⟨hp, hq⟩, ⟨a', hp, hq, rfl⟩⟩
@[simp] theorem exists_apply_eq_apply {α β : Type*} (f : α → β) (a' : α) : ∃ a, f a = f a' :=
⟨a', rfl⟩
@[simp] theorem exists_apply_eq_apply' {α β : Type*} (f : α → β) (a' : α) : ∃ a, f a' = f a :=
⟨a', rfl⟩
@[simp] theorem exists_exists_and_eq_and {f : α → β} {p : α → Prop} {q : β → Prop} :
(∃ b, (∃ a, p a ∧ f a = b) ∧ q b) ↔ ∃ a, p a ∧ q (f a) :=
⟨λ ⟨b, ⟨a, ha, hab⟩, hb⟩, ⟨a, ha, hab.symm ▸ hb⟩, λ ⟨a, hp, hq⟩, ⟨f a, ⟨a, hp, rfl⟩, hq⟩⟩
@[simp] theorem exists_exists_eq_and {f : α → β} {p : β → Prop} :
(∃ b, (∃ a, f a = b) ∧ p b) ↔ ∃ a, p (f a) :=
⟨λ ⟨b, ⟨a, ha⟩, hb⟩, ⟨a, ha.symm ▸ hb⟩, λ ⟨a, ha⟩, ⟨f a, ⟨a, rfl⟩, ha⟩⟩
@[simp] theorem forall_apply_eq_imp_iff {f : α → β} {p : β → Prop} :
(∀ a, ∀ b, f a = b → p b) ↔ (∀ a, p (f a)) :=
⟨λ h a, h a (f a) rfl, λ h a b hab, hab ▸ h a⟩
@[simp] theorem forall_apply_eq_imp_iff' {f : α → β} {p : β → Prop} :
(∀ b, ∀ a, f a = b → p b) ↔ (∀ a, p (f a)) :=
by { rw forall_swap, simp }
@[simp] theorem forall_eq_apply_imp_iff {f : α → β} {p : β → Prop} :
(∀ a, ∀ b, b = f a → p b) ↔ (∀ a, p (f a)) :=
by simp [@eq_comm _ _ (f _)]
@[simp] theorem forall_eq_apply_imp_iff' {f : α → β} {p : β → Prop} :
(∀ b, ∀ a, b = f a → p b) ↔ (∀ a, p (f a)) :=
by { rw forall_swap, simp }
@[simp] theorem forall_apply_eq_imp_iff₂ {f : α → β} {p : α → Prop} {q : β → Prop} :
(∀ b, ∀ a, p a → f a = b → q b) ↔ ∀ a, p a → q (f a) :=
⟨λ h a ha, h (f a) a ha rfl, λ h b a ha hb, hb ▸ h a ha⟩
@[simp] theorem exists_eq_left' {a' : α} : (∃ a, a' = a ∧ p a) ↔ p a' :=
by simp [@eq_comm _ a']
@[simp] theorem exists_eq_right' {a' : α} : (∃ a, p a ∧ a' = a) ↔ p a' :=
by simp [@eq_comm _ a']
theorem exists_comm {p : α → β → Prop} : (∃ a b, p a b) ↔ ∃ b a, p a b :=
⟨λ ⟨a, b, h⟩, ⟨b, a, h⟩, λ ⟨b, a, h⟩, ⟨a, b, h⟩⟩
theorem forall_or_of_or_forall (h : b ∨ ∀x, p x) (x) : b ∨ p x :=
h.imp_right $ λ h₂, h₂ x
-- See Note [decidable namespace]
protected theorem decidable.forall_or_distrib_left {q : Prop} {p : α → Prop} [decidable q] :
(∀x, q ∨ p x) ↔ q ∨ (∀x, p x) :=
⟨λ h, if hq : q then or.inl hq else or.inr $ λ x, (h x).resolve_left hq,
forall_or_of_or_forall⟩
theorem forall_or_distrib_left {q : Prop} {p : α → Prop} :
(∀x, q ∨ p x) ↔ q ∨ (∀x, p x) := decidable.forall_or_distrib_left
-- See Note [decidable namespace]
protected theorem decidable.forall_or_distrib_right {q : Prop} {p : α → Prop} [decidable q] :
(∀x, p x ∨ q) ↔ (∀x, p x) ∨ q :=
by simp [or_comm, decidable.forall_or_distrib_left]
theorem forall_or_distrib_right {q : Prop} {p : α → Prop} :
(∀x, p x ∨ q) ↔ (∀x, p x) ∨ q := decidable.forall_or_distrib_right
/-- A predicate holds everywhere on the image of a surjective functions iff
it holds everywhere. -/
theorem forall_iff_forall_surj
{α β : Type*} {f : α → β} (h : function.surjective f) {P : β → Prop} :
(∀ a, P (f a)) ↔ ∀ b, P b :=
⟨λ ha b, by cases h b with a hab; rw ←hab; exact ha a, λ hb a, hb $ f a⟩
@[simp] theorem exists_prop {p q : Prop} : (∃ h : p, q) ↔ p ∧ q :=
⟨λ ⟨h₁, h₂⟩, ⟨h₁, h₂⟩, λ ⟨h₁, h₂⟩, ⟨h₁, h₂⟩⟩
@[simp] theorem exists_false : ¬ (∃a:α, false) := assume ⟨a, h⟩, h
@[simp] lemma exists_unique_false : ¬ (∃! (a : α), false) := assume ⟨a, h, h'⟩, h
theorem Exists.fst {p : b → Prop} : Exists p → b
| ⟨h, _⟩ := h
theorem Exists.snd {p : b → Prop} : ∀ h : Exists p, p h.fst
| ⟨_, h⟩ := h
theorem forall_prop_of_true {p : Prop} {q : p → Prop} (h : p) : (∀ h' : p, q h') ↔ q h :=
@forall_const (q h) p ⟨h⟩
theorem exists_prop_of_true {p : Prop} {q : p → Prop} (h : p) : (∃ h' : p, q h') ↔ q h :=
@exists_const (q h) p ⟨h⟩
theorem forall_prop_of_false {p : Prop} {q : p → Prop} (hn : ¬ p) :
(∀ h' : p, q h') ↔ true :=
iff_true_intro $ λ h, hn.elim h
theorem exists_prop_of_false {p : Prop} {q : p → Prop} : ¬ p → ¬ (∃ h' : p, q h') :=
mt Exists.fst
@[congr] lemma exists_prop_congr {p p' : Prop} {q q' : p → Prop}
(hq : ∀ h, q h ↔ q' h) (hp : p ↔ p') : Exists q ↔ ∃ h : p', q' (hp.2 h) :=
⟨λ ⟨_, _⟩, ⟨hp.1 ‹_›, (hq _).1 ‹_›⟩, λ ⟨_, _⟩, ⟨_, (hq _).2 ‹_›⟩⟩
@[congr] lemma exists_prop_congr' {p p' : Prop} {q q' : p → Prop}
(hq : ∀ h, q h ↔ q' h) (hp : p ↔ p') : Exists q = ∃ h : p', q' (hp.2 h) :=
propext (exists_prop_congr hq _)
@[simp] lemma exists_true_left (p : true → Prop) : (∃ x, p x) ↔ p true.intro :=
exists_prop_of_true _
@[simp] lemma exists_false_left (p : false → Prop) : ¬ ∃ x, p x :=
exists_prop_of_false not_false
lemma exists_unique.exists {α : Sort*} {p : α → Prop} (h : ∃! x, p x) : ∃ x, p x :=
exists.elim h (λ x hx, ⟨x, and.left hx⟩)
lemma exists_unique.unique {α : Sort*} {p : α → Prop} (h : ∃! x, p x)
{y₁ y₂ : α} (py₁ : p y₁) (py₂ : p y₂) : y₁ = y₂ :=
unique_of_exists_unique h py₁ py₂
@[congr] lemma forall_prop_congr {p p' : Prop} {q q' : p → Prop}
(hq : ∀ h, q h ↔ q' h) (hp : p ↔ p') : (∀ h, q h) ↔ ∀ h : p', q' (hp.2 h) :=
⟨λ h1 h2, (hq _).1 (h1 (hp.2 _)), λ h1 h2, (hq _).2 (h1 (hp.1 h2))⟩
@[congr] lemma forall_prop_congr' {p p' : Prop} {q q' : p → Prop}
(hq : ∀ h, q h ↔ q' h) (hp : p ↔ p') : (∀ h, q h) = ∀ h : p', q' (hp.2 h) :=
propext (forall_prop_congr hq _)
@[simp] lemma forall_true_left (p : true → Prop) : (∀ x, p x) ↔ p true.intro :=
forall_prop_of_true _
@[simp] lemma forall_false_left (p : false → Prop) : (∀ x, p x) ↔ true :=
forall_prop_of_false not_false
@[simp] lemma exists_unique_iff_exists {α : Sort*} [subsingleton α] {p : α → Prop} :
(∃! x, p x) ↔ ∃ x, p x :=
⟨λ h, h.exists, Exists.imp $ λ x hx, ⟨hx, λ y _, subsingleton.elim y x⟩⟩
lemma exists_unique.elim2 {α : Sort*} {p : α → Sort*} [∀ x, subsingleton (p x)]
{q : Π x (h : p x), Prop} {b : Prop} (h₂ : ∃! x (h : p x), q x h)
(h₁ : ∀ x (h : p x), q x h → (∀ y (hy : p y), q y hy → y = x) → b) : b :=
begin
simp only [exists_unique_iff_exists] at h₂,
apply h₂.elim,
exact λ x ⟨hxp, hxq⟩ H, h₁ x hxp hxq (λ y hyp hyq, H y ⟨hyp, hyq⟩)
end
lemma exists_unique.intro2 {α : Sort*} {p : α → Sort*} [∀ x, subsingleton (p x)]
{q : Π (x : α) (h : p x), Prop} (w : α) (hp : p w) (hq : q w hp)
(H : ∀ y (hy : p y), q y hy → y = w) :
∃! x (hx : p x), q x hx :=
begin
simp only [exists_unique_iff_exists],
exact exists_unique.intro w ⟨hp, hq⟩ (λ y ⟨hyp, hyq⟩, H y hyp hyq)
end
lemma exists_unique.exists2 {α : Sort*} {p : α → Sort*} {q : Π (x : α) (h : p x), Prop}
(h : ∃! x (hx : p x), q x hx) :
∃ x (hx : p x), q x hx :=
h.exists.imp (λ x hx, hx.exists)
lemma exists_unique.unique2 {α : Sort*} {p : α → Sort*} [∀ x, subsingleton (p x)]
{q : Π (x : α) (hx : p x), Prop} (h : ∃! x (hx : p x), q x hx)
{y₁ y₂ : α} (hpy₁ : p y₁) (hqy₁ : q y₁ hpy₁)
(hpy₂ : p y₂) (hqy₂ : q y₂ hpy₂) : y₁ = y₂ :=
begin
simp only [exists_unique_iff_exists] at h,
exact h.unique ⟨hpy₁, hqy₁⟩ ⟨hpy₂, hqy₂⟩
end
end quantifiers
/-! ### Classical lemmas -/
namespace classical
variables {α : Sort*} {p : α → Prop}
theorem cases {p : Prop → Prop} (h1 : p true) (h2 : p false) : ∀a, p a :=
assume a, cases_on a h1 h2
/- use shortened names to avoid conflict when classical namespace is open. -/
noncomputable lemma dec (p : Prop) : decidable p := -- see Note [classical lemma]
by apply_instance
noncomputable lemma dec_pred (p : α → Prop) : decidable_pred p := -- see Note [classical lemma]
by apply_instance
noncomputable lemma dec_rel (p : α → α → Prop) : decidable_rel p := -- see Note [classical lemma]
by apply_instance
noncomputable lemma dec_eq (α : Sort*) : decidable_eq α := -- see Note [classical lemma]
by apply_instance
/--
We make decidability results that depends on `classical.choice` noncomputable lemmas.
* We have to mark them as noncomputable, because otherwise Lean will try to generate bytecode
for them, and fail because it depends on `classical.choice`.
* We make them lemmas, and not definitions, because otherwise later definitions will raise
\"failed to generate bytecode\" errors when writing something like
`letI := classical.dec_eq _`.
Cf. <https://leanprover-community.github.io/archive/stream/113488-general/topic/noncomputable.20theorem.html>
-/
library_note "classical lemma"
/-- Construct a function from a default value `H0`, and a function to use if there exists a value
satisfying the predicate. -/
@[elab_as_eliminator]
noncomputable def {u} exists_cases {C : Sort u} (H0 : C) (H : ∀ a, p a → C) : C :=
if h : ∃ a, p a then H (classical.some h) (classical.some_spec h) else H0
lemma some_spec2 {α : Sort*} {p : α → Prop} {h : ∃a, p a}
(q : α → Prop) (hpq : ∀a, p a → q a) : q (some h) :=
hpq _ $ some_spec _
/-- A version of classical.indefinite_description which is definitionally equal to a pair -/
noncomputable def subtype_of_exists {α : Type*} {P : α → Prop} (h : ∃ x, P x) : {x // P x} :=
⟨classical.some h, classical.some_spec h⟩
end classical
/-- This function has the same type as `exists.rec_on`, and can be used to case on an equality,
but `exists.rec_on` can only eliminate into Prop, while this version eliminates into any universe
using the axiom of choice. -/
@[elab_as_eliminator]
noncomputable def {u} exists.classical_rec_on
{α} {p : α → Prop} (h : ∃ a, p a) {C : Sort u} (H : ∀ a, p a → C) : C :=
H (classical.some h) (classical.some_spec h)
/-! ### Declarations about bounded quantifiers -/
section bounded_quantifiers
variables {α : Sort*} {r p q : α → Prop} {P Q : ∀ x, p x → Prop} {b : Prop}
theorem bex_def : (∃ x (h : p x), q x) ↔ ∃ x, p x ∧ q x :=
⟨λ ⟨x, px, qx⟩, ⟨x, px, qx⟩, λ ⟨x, px, qx⟩, ⟨x, px, qx⟩⟩
theorem bex.elim {b : Prop} : (∃ x h, P x h) → (∀ a h, P a h → b) → b
| ⟨a, h₁, h₂⟩ h' := h' a h₁ h₂
theorem bex.intro (a : α) (h₁ : p a) (h₂ : P a h₁) : ∃ x (h : p x), P x h :=
⟨a, h₁, h₂⟩
theorem ball_congr (H : ∀ x h, P x h ↔ Q x h) :
(∀ x h, P x h) ↔ (∀ x h, Q x h) :=
forall_congr $ λ x, forall_congr (H x)
theorem bex_congr (H : ∀ x h, P x h ↔ Q x h) :
(∃ x h, P x h) ↔ (∃ x h, Q x h) :=
exists_congr $ λ x, exists_congr (H x)
theorem bex_eq_left {a : α} : (∃ x (_ : x = a), p x) ↔ p a :=
by simp only [exists_prop, exists_eq_left]
theorem ball.imp_right (H : ∀ x h, (P x h → Q x h))
(h₁ : ∀ x h, P x h) (x h) : Q x h :=
H _ _ $ h₁ _ _
theorem bex.imp_right (H : ∀ x h, (P x h → Q x h)) :
(∃ x h, P x h) → ∃ x h, Q x h
| ⟨x, h, h'⟩ := ⟨_, _, H _ _ h'⟩
theorem ball.imp_left (H : ∀ x, p x → q x)
(h₁ : ∀ x, q x → r x) (x) (h : p x) : r x :=
h₁ _ $ H _ h
theorem bex.imp_left (H : ∀ x, p x → q x) :
(∃ x (_ : p x), r x) → ∃ x (_ : q x), r x
| ⟨x, hp, hr⟩ := ⟨x, H _ hp, hr⟩
theorem ball_of_forall (h : ∀ x, p x) (x) : p x :=
h x
theorem forall_of_ball (H : ∀ x, p x) (h : ∀ x, p x → q x) (x) : q x :=
h x $ H x
theorem bex_of_exists (H : ∀ x, p x) : (∃ x, q x) → ∃ x (_ : p x), q x
| ⟨x, hq⟩ := ⟨x, H x, hq⟩
theorem exists_of_bex : (∃ x (_ : p x), q x) → ∃ x, q x
| ⟨x, _, hq⟩ := ⟨x, hq⟩
@[simp] theorem bex_imp_distrib : ((∃ x h, P x h) → b) ↔ (∀ x h, P x h → b) :=
by simp
theorem not_bex : (¬ ∃ x h, P x h) ↔ ∀ x h, ¬ P x h :=
bex_imp_distrib
theorem not_ball_of_bex_not : (∃ x h, ¬ P x h) → ¬ ∀ x h, P x h
| ⟨x, h, hp⟩ al := hp $ al x h
-- See Note [decidable namespace]
protected theorem decidable.not_ball [decidable (∃ x h, ¬ P x h)] [∀ x h, decidable (P x h)] :
(¬ ∀ x h, P x h) ↔ (∃ x h, ¬ P x h) :=
⟨not.decidable_imp_symm $ λ nx x h, nx.decidable_imp_symm $ λ h', ⟨x, h, h'⟩,
not_ball_of_bex_not⟩
theorem not_ball : (¬ ∀ x h, P x h) ↔ (∃ x h, ¬ P x h) := decidable.not_ball
theorem ball_true_iff (p : α → Prop) : (∀ x, p x → true) ↔ true :=
iff_true_intro (λ h hrx, trivial)
theorem ball_and_distrib : (∀ x h, P x h ∧ Q x h) ↔ (∀ x h, P x h) ∧ (∀ x h, Q x h) :=
iff.trans (forall_congr $ λ x, forall_and_distrib) forall_and_distrib
theorem bex_or_distrib : (∃ x h, P x h ∨ Q x h) ↔ (∃ x h, P x h) ∨ (∃ x h, Q x h) :=
iff.trans (exists_congr $ λ x, exists_or_distrib) exists_or_distrib
theorem ball_or_left_distrib : (∀ x, p x ∨ q x → r x) ↔ (∀ x, p x → r x) ∧ (∀ x, q x → r x) :=
iff.trans (forall_congr $ λ x, or_imp_distrib) forall_and_distrib
theorem bex_or_left_distrib :
(∃ x (_ : p x ∨ q x), r x) ↔ (∃ x (_ : p x), r x) ∨ (∃ x (_ : q x), r x) :=
by simp only [exists_prop]; exact
iff.trans (exists_congr $ λ x, or_and_distrib_right) exists_or_distrib
end bounded_quantifiers
namespace classical
local attribute [instance] prop_decidable
theorem not_ball {α : Sort*} {p : α → Prop} {P : Π (x : α), p x → Prop} :
(¬ ∀ x h, P x h) ↔ (∃ x h, ¬ P x h) := _root_.not_ball
end classical
lemma ite_eq_iff {α} {p : Prop} [decidable p] {a b c : α} :
(if p then a else b) = c ↔ p ∧ a = c ∨ ¬p ∧ b = c :=
by by_cases p; simp *
@[simp] lemma ite_eq_left_iff {α} {p : Prop} [decidable p] {a b : α} :
(if p then a else b) = a ↔ (¬p → b = a) :=
by by_cases p; simp *
@[simp] lemma ite_eq_right_iff {α} {p : Prop} [decidable p] {a b : α} :
(if p then a else b) = b ↔ (p → a = b) :=
by by_cases p; simp *
/-! ### Declarations about `nonempty` -/
section nonempty
universe variables u v w
variables {α : Type u} {β : Type v} {γ : α → Type w}
attribute [simp] nonempty_of_inhabited
@[priority 20]
instance has_zero.nonempty [has_zero α] : nonempty α := ⟨0⟩
@[priority 20]
instance has_one.nonempty [has_one α] : nonempty α := ⟨1⟩
lemma exists_true_iff_nonempty {α : Sort*} : (∃a:α, true) ↔ nonempty α :=
iff.intro (λ⟨a, _⟩, ⟨a⟩) (λ⟨a⟩, ⟨a, trivial⟩)
@[simp] lemma nonempty_Prop {p : Prop} : nonempty p ↔ p :=
iff.intro (assume ⟨h⟩, h) (assume h, ⟨h⟩)
lemma not_nonempty_iff_imp_false : ¬ nonempty α ↔ α → false :=
⟨λ h a, h ⟨a⟩, λ h ⟨a⟩, h a⟩
@[simp] lemma nonempty_sigma : nonempty (Σa:α, γ a) ↔ (∃a:α, nonempty (γ a)) :=
iff.intro (assume ⟨⟨a, c⟩⟩, ⟨a, ⟨c⟩⟩) (assume ⟨a, ⟨c⟩⟩, ⟨⟨a, c⟩⟩)
@[simp] lemma nonempty_subtype {α : Sort u} {p : α → Prop} : nonempty (subtype p) ↔ (∃a:α, p a) :=
iff.intro (assume ⟨⟨a, h⟩⟩, ⟨a, h⟩) (assume ⟨a, h⟩, ⟨⟨a, h⟩⟩)
@[simp] lemma nonempty_prod : nonempty (α × β) ↔ (nonempty α ∧ nonempty β) :=
iff.intro (assume ⟨⟨a, b⟩⟩, ⟨⟨a⟩, ⟨b⟩⟩) (assume ⟨⟨a⟩, ⟨b⟩⟩, ⟨⟨a, b⟩⟩)
@[simp] lemma nonempty_pprod {α : Sort u} {β : Sort v} :
nonempty (pprod α β) ↔ (nonempty α ∧ nonempty β) :=
iff.intro (assume ⟨⟨a, b⟩⟩, ⟨⟨a⟩, ⟨b⟩⟩) (assume ⟨⟨a⟩, ⟨b⟩⟩, ⟨⟨a, b⟩⟩)
@[simp] lemma nonempty_sum : nonempty (α ⊕ β) ↔ (nonempty α ∨ nonempty β) :=
iff.intro
(assume ⟨h⟩, match h with sum.inl a := or.inl ⟨a⟩ | sum.inr b := or.inr ⟨b⟩ end)
(assume h, match h with or.inl ⟨a⟩ := ⟨sum.inl a⟩ | or.inr ⟨b⟩ := ⟨sum.inr b⟩ end)
@[simp] lemma nonempty_psum {α : Sort u} {β : Sort v} :
nonempty (psum α β) ↔ (nonempty α ∨ nonempty β) :=
iff.intro
(assume ⟨h⟩, match h with psum.inl a := or.inl ⟨a⟩ | psum.inr b := or.inr ⟨b⟩ end)
(assume h, match h with or.inl ⟨a⟩ := ⟨psum.inl a⟩ | or.inr ⟨b⟩ := ⟨psum.inr b⟩ end)
@[simp] lemma nonempty_psigma {α : Sort u} {β : α → Sort v} :
nonempty (psigma β) ↔ (∃a:α, nonempty (β a)) :=
iff.intro (assume ⟨⟨a, c⟩⟩, ⟨a, ⟨c⟩⟩) (assume ⟨a, ⟨c⟩⟩, ⟨⟨a, c⟩⟩)
@[simp] lemma nonempty_empty : ¬ nonempty empty :=
assume ⟨h⟩, h.elim
@[simp] lemma nonempty_ulift : nonempty (ulift α) ↔ nonempty α :=
iff.intro (assume ⟨⟨a⟩⟩, ⟨a⟩) (assume ⟨a⟩, ⟨⟨a⟩⟩)
@[simp] lemma nonempty_plift {α : Sort u} : nonempty (plift α) ↔ nonempty α :=
iff.intro (assume ⟨⟨a⟩⟩, ⟨a⟩) (assume ⟨a⟩, ⟨⟨a⟩⟩)
@[simp] lemma nonempty.forall {α : Sort u} {p : nonempty α → Prop} :
(∀h:nonempty α, p h) ↔ (∀a, p ⟨a⟩) :=
iff.intro (assume h a, h _) (assume h ⟨a⟩, h _)
@[simp] lemma nonempty.exists {α : Sort u} {p : nonempty α → Prop} :
(∃h:nonempty α, p h) ↔ (∃a, p ⟨a⟩) :=
iff.intro (assume ⟨⟨a⟩, h⟩, ⟨a, h⟩) (assume ⟨a, h⟩, ⟨⟨a⟩, h⟩)
lemma classical.nonempty_pi {α : Sort u} {β : α → Sort v} :
nonempty (Πa:α, β a) ↔ (∀a:α, nonempty (β a)) :=
iff.intro (assume ⟨f⟩ a, ⟨f a⟩) (assume f, ⟨assume a, classical.choice $ f a⟩)
/-- Using `classical.choice`, lifts a (`Prop`-valued) `nonempty` instance to a (`Type`-valued)
`inhabited` instance. `classical.inhabited_of_nonempty` already exists, in
`core/init/classical.lean`, but the assumption is not a type class argument,
which makes it unsuitable for some applications. -/
noncomputable def classical.inhabited_of_nonempty' {α : Sort u} [h : nonempty α] : inhabited α :=
⟨classical.choice h⟩
/-- Using `classical.choice`, extracts a term from a `nonempty` type. -/
@[reducible] protected noncomputable def nonempty.some {α : Sort u} (h : nonempty α) : α :=
classical.choice h
/-- Using `classical.choice`, extracts a term from a `nonempty` type. -/
@[reducible] protected noncomputable def classical.arbitrary (α : Sort u) [h : nonempty α] : α :=
classical.choice h
/-- Given `f : α → β`, if `α` is nonempty then `β` is also nonempty.
`nonempty` cannot be a `functor`, because `functor` is restricted to `Type`. -/
lemma nonempty.map {α : Sort u} {β : Sort v} (f : α → β) : nonempty α → nonempty β
| ⟨h⟩ := ⟨f h⟩
protected lemma nonempty.map2 {α β γ : Sort*} (f : α → β → γ) : nonempty α → nonempty β → nonempty γ
| ⟨x⟩ ⟨y⟩ := ⟨f x y⟩
protected lemma nonempty.congr {α : Sort u} {β : Sort v} (f : α → β) (g : β → α) :
nonempty α ↔ nonempty β :=
⟨nonempty.map f, nonempty.map g⟩
lemma nonempty.elim_to_inhabited {α : Sort*} [h : nonempty α] {p : Prop}
(f : inhabited α → p) : p :=
h.elim $ f ∘ inhabited.mk
instance {α β} [h : nonempty α] [h2 : nonempty β] : nonempty (α × β) :=
h.elim $ λ g, h2.elim $ λ g2, ⟨⟨g, g2⟩⟩
end nonempty
section ite
/-- A `dite` whose results do not actually depend on the condition may be reduced to an `ite`. -/
@[simp]
lemma dite_eq_ite (P : Prop) [decidable P] {α : Sort*} (x y : α) :
dite P (λ h, x) (λ h, y) = ite P x y := rfl
/-- A function applied to a `dite` is a `dite` of that function applied to each of the branches. -/
lemma apply_dite {α β : Sort*} (f : α → β) (P : Prop) [decidable P] (x : P → α) (y : ¬P → α) :
f (dite P x y) = dite P (λ h, f (x h)) (λ h, f (y h)) :=
by { by_cases h : P; simp [h] }
/-- A function applied to a `ite` is a `ite` of that function applied to each of the branches. -/
lemma apply_ite {α β : Sort*} (f : α → β) (P : Prop) [decidable P] (x y : α) :
f (ite P x y) = ite P (f x) (f y) :=
apply_dite f P (λ _, x) (λ _, y)
/-- A two-argument function applied to two `dite`s is a `dite` of that two-argument function
applied to each of the branches. -/
lemma apply_dite2 {α β γ : Sort*} (f : α → β → γ) (P : Prop) [decidable P] (a : P → α)
(b : ¬P → α) (c : P → β) (d : ¬P → β) :
f (dite P a b) (dite P c d) = dite P (λ h, f (a h) (c h)) (λ h, f (b h) (d h)) :=
by { by_cases h : P; simp [h] }
/-- A two-argument function applied to two `ite`s is a `ite` of that two-argument function
applied to each of the branches. -/
lemma apply_ite2 {α β γ : Sort*} (f : α → β → γ) (P : Prop) [decidable P] (a b : α) (c d : β) :
f (ite P a b) (ite P c d) = ite P (f a c) (f b d) :=
apply_dite2 f P (λ _, a) (λ _, b) (λ _, c) (λ _, d)
/-- A 'dite' producing a `Pi` type `Π a, β a`, applied to a value `x : α`
is a `dite` that applies either branch to `x`. -/
lemma dite_apply {α : Sort*} {β : α → Sort*} (P : Prop) [decidable P]
(f : P → Π a, β a) (g : ¬ P → Π a, β a) (x : α) :
(dite P f g) x = dite P (λ h, f h x) (λ h, g h x) :=
by { by_cases h : P; simp [h] }
/-- A 'ite' producing a `Pi` type `Π a, β a`, applied to a value `x : α`
is a `ite` that applies either branch to `x` -/
lemma ite_apply {α : Sort*} {β : α → Sort*} (P : Prop) [decidable P]
(f g : Π a, β a) (x : α) :
(ite P f g) x = ite P (f x) (g x) :=
dite_apply P (λ _, f) (λ _, g) x
/-- Negation of the condition `P : Prop` in a `dite` is the same as swapping the branches. -/
@[simp] lemma dite_not {α : Sort*} (P : Prop) [decidable P] (x : ¬ P → α) (y : ¬¬ P → α) :
dite (¬ P) x y = dite P (λ h, y (not_not_intro h)) x :=
by { by_cases h : P; simp [h] }
/-- Negation of the condition `P : Prop` in a `ite` is the same as swapping the branches. -/
@[simp] lemma ite_not {α : Sort*} (P : Prop) [decidable P] (x y : α) :
ite (¬ P) x y = ite P y x :=
dite_not P (λ _, x) (λ _, y)
lemma ite_and {α} {p q : Prop} [decidable p] [decidable q] {x y : α} :
ite (p ∧ q) x y = ite p (ite q x y) y :=
by { by_cases hp : p; by_cases hq : q; simp [hp, hq] }
end ite
-/
|
a15ac09c8641e74d41f62febaabc63e7345a9b90 | c777c32c8e484e195053731103c5e52af26a25d1 | /src/analysis/convex/gauge.lean | ad9c43b0664dd799dba93fb614c3f937d0110aaa | [
"Apache-2.0"
] | permissive | kbuzzard/mathlib | 2ff9e85dfe2a46f4b291927f983afec17e946eb8 | 58537299e922f9c77df76cb613910914a479c1f7 | refs/heads/master | 1,685,313,702,744 | 1,683,974,212,000 | 1,683,974,212,000 | 128,185,277 | 1 | 0 | null | 1,522,920,600,000 | 1,522,920,600,000 | null | UTF-8 | Lean | false | false | 18,636 | lean | /-
Copyright (c) 2021 Yaël Dillies, Bhavik Mehta. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies, Bhavik Mehta
-/
import analysis.convex.basic
import analysis.normed_space.pointwise
import analysis.seminorm
import data.is_R_or_C.basic
import tactic.congrm
/-!
# The Minkowksi functional
This file defines the Minkowski functional, aka gauge.
The Minkowski functional of a set `s` is the function which associates each point to how much you
need to scale `s` for `x` to be inside it. When `s` is symmetric, convex and absorbent, its gauge is
a seminorm. Reciprocally, any seminorm arises as the gauge of some set, namely its unit ball. This
induces the equivalence of seminorms and locally convex topological vector spaces.
## Main declarations
For a real vector space,
* `gauge`: Aka Minkowksi functional. `gauge s x` is the least (actually, an infimum) `r` such
that `x ∈ r • s`.
* `gauge_seminorm`: The Minkowski functional as a seminorm, when `s` is symmetric, convex and
absorbent.
## References
* [H. H. Schaefer, *Topological Vector Spaces*][schaefer1966]
## Tags
Minkowski functional, gauge
-/
open normed_field set
open_locale pointwise
noncomputable theory
variables {𝕜 E F : Type*}
section add_comm_group
variables [add_comm_group E] [module ℝ E]
/--The Minkowski functional. Given a set `s` in a real vector space, `gauge s` is the functional
which sends `x : E` to the smallest `r : ℝ` such that `x` is in `s` scaled by `r`. -/
def gauge (s : set E) (x : E) : ℝ := Inf {r : ℝ | 0 < r ∧ x ∈ r • s}
variables {s t : set E} {a : ℝ} {x : E}
lemma gauge_def : gauge s x = Inf {r ∈ set.Ioi 0 | x ∈ r • s} := rfl
/-- An alternative definition of the gauge using scalar multiplication on the element rather than on
the set. -/
lemma gauge_def' : gauge s x = Inf {r ∈ set.Ioi 0 | r⁻¹ • x ∈ s} :=
begin
congrm Inf (λ r, _),
exact and_congr_right (λ hr, mem_smul_set_iff_inv_smul_mem₀ hr.ne' _ _),
end
private lemma gauge_set_bdd_below : bdd_below {r : ℝ | 0 < r ∧ x ∈ r • s} := ⟨0, λ r hr, hr.1.le⟩
/-- If the given subset is `absorbent` then the set we take an infimum over in `gauge` is nonempty,
which is useful for proving many properties about the gauge. -/
lemma absorbent.gauge_set_nonempty (absorbs : absorbent ℝ s) :
{r : ℝ | 0 < r ∧ x ∈ r • s}.nonempty :=
let ⟨r, hr₁, hr₂⟩ := absorbs x in ⟨r, hr₁, hr₂ r (real.norm_of_nonneg hr₁.le).ge⟩
lemma gauge_mono (hs : absorbent ℝ s) (h : s ⊆ t) : gauge t ≤ gauge s :=
λ x, cInf_le_cInf gauge_set_bdd_below hs.gauge_set_nonempty $ λ r hr, ⟨hr.1, smul_set_mono h hr.2⟩
lemma exists_lt_of_gauge_lt (absorbs : absorbent ℝ s) (h : gauge s x < a) :
∃ b, 0 < b ∧ b < a ∧ x ∈ b • s :=
begin
obtain ⟨b, ⟨hb, hx⟩, hba⟩ := exists_lt_of_cInf_lt absorbs.gauge_set_nonempty h,
exact ⟨b, hb, hba, hx⟩,
end
/-- The gauge evaluated at `0` is always zero (mathematically this requires `0` to be in the set `s`
but, the real infimum of the empty set in Lean being defined as `0`, it holds unconditionally). -/
@[simp] lemma gauge_zero : gauge s 0 = 0 :=
begin
rw gauge_def',
by_cases (0 : E) ∈ s,
{ simp only [smul_zero, sep_true, h, cInf_Ioi] },
{ simp only [smul_zero, sep_false, h, real.Inf_empty] }
end
@[simp] lemma gauge_zero' : gauge (0 : set E) = 0 :=
begin
ext,
rw gauge_def',
obtain rfl | hx := eq_or_ne x 0,
{ simp only [cInf_Ioi, mem_zero, pi.zero_apply, eq_self_iff_true, sep_true, smul_zero] },
{ simp only [mem_zero, pi.zero_apply, inv_eq_zero, smul_eq_zero],
convert real.Inf_empty,
exact eq_empty_iff_forall_not_mem.2 (λ r hr, hr.2.elim (ne_of_gt hr.1) hx) }
end
@[simp] lemma gauge_empty : gauge (∅ : set E) = 0 :=
by { ext, simp only [gauge_def', real.Inf_empty, mem_empty_iff_false, pi.zero_apply, sep_false] }
lemma gauge_of_subset_zero (h : s ⊆ 0) : gauge s = 0 :=
by { obtain rfl | rfl := subset_singleton_iff_eq.1 h, exacts [gauge_empty, gauge_zero'] }
/-- The gauge is always nonnegative. -/
lemma gauge_nonneg (x : E) : 0 ≤ gauge s x := real.Inf_nonneg _ $ λ x hx, hx.1.le
lemma gauge_neg (symmetric : ∀ x ∈ s, -x ∈ s) (x : E) : gauge s (-x) = gauge s x :=
begin
have : ∀ x, -x ∈ s ↔ x ∈ s := λ x, ⟨λ h, by simpa using symmetric _ h, symmetric x⟩,
simp_rw [gauge_def', smul_neg, this]
end
lemma gauge_neg_set_neg (x : E) : gauge (-s) (-x) = gauge s x :=
by simp_rw [gauge_def', smul_neg, neg_mem_neg]
lemma gauge_neg_set_eq_gauge_neg (x : E) : gauge (-s) x = gauge s (-x) :=
by rw [← gauge_neg_set_neg, neg_neg]
lemma gauge_le_of_mem (ha : 0 ≤ a) (hx : x ∈ a • s) : gauge s x ≤ a :=
begin
obtain rfl | ha' := ha.eq_or_lt,
{ rw [mem_singleton_iff.1 (zero_smul_set_subset _ hx), gauge_zero] },
{ exact cInf_le gauge_set_bdd_below ⟨ha', hx⟩ }
end
lemma gauge_le_eq (hs₁ : convex ℝ s) (hs₀ : (0 : E) ∈ s) (hs₂ : absorbent ℝ s) (ha : 0 ≤ a) :
{x | gauge s x ≤ a} = ⋂ (r : ℝ) (H : a < r), r • s :=
begin
ext,
simp_rw [set.mem_Inter, set.mem_set_of_eq],
refine ⟨λ h r hr, _, λ h, le_of_forall_pos_lt_add (λ ε hε, _)⟩,
{ have hr' := ha.trans_lt hr,
rw mem_smul_set_iff_inv_smul_mem₀ hr'.ne',
obtain ⟨δ, δ_pos, hδr, hδ⟩ := exists_lt_of_gauge_lt hs₂ (h.trans_lt hr),
suffices : (r⁻¹ * δ) • δ⁻¹ • x ∈ s,
{ rwa [smul_smul, mul_inv_cancel_right₀ δ_pos.ne'] at this },
rw mem_smul_set_iff_inv_smul_mem₀ δ_pos.ne' at hδ,
refine hs₁.smul_mem_of_zero_mem hs₀ hδ ⟨by positivity, _⟩,
rw [inv_mul_le_iff hr', mul_one],
exact hδr.le },
{ have hε' := (lt_add_iff_pos_right a).2 (half_pos hε),
exact (gauge_le_of_mem (ha.trans hε'.le) $ h _ hε').trans_lt
(add_lt_add_left (half_lt_self hε) _) }
end
lemma gauge_lt_eq' (absorbs : absorbent ℝ s) (a : ℝ) :
{x | gauge s x < a} = ⋃ (r : ℝ) (H : 0 < r) (H : r < a), r • s :=
begin
ext,
simp_rw [mem_set_of_eq, mem_Union, exists_prop],
exact ⟨exists_lt_of_gauge_lt absorbs,
λ ⟨r, hr₀, hr₁, hx⟩, (gauge_le_of_mem hr₀.le hx).trans_lt hr₁⟩,
end
lemma gauge_lt_eq (absorbs : absorbent ℝ s) (a : ℝ) :
{x | gauge s x < a} = ⋃ (r ∈ set.Ioo 0 (a : ℝ)), r • s :=
begin
ext,
simp_rw [mem_set_of_eq, mem_Union, exists_prop, mem_Ioo, and_assoc],
exact ⟨exists_lt_of_gauge_lt absorbs,
λ ⟨r, hr₀, hr₁, hx⟩, (gauge_le_of_mem hr₀.le hx).trans_lt hr₁⟩,
end
lemma gauge_lt_one_subset_self (hs : convex ℝ s) (h₀ : (0 : E) ∈ s) (absorbs : absorbent ℝ s) :
{x | gauge s x < 1} ⊆ s :=
begin
rw gauge_lt_eq absorbs,
refine set.Union₂_subset (λ r hr _, _),
rintro ⟨y, hy, rfl⟩,
exact hs.smul_mem_of_zero_mem h₀ hy (Ioo_subset_Icc_self hr),
end
lemma gauge_le_one_of_mem {x : E} (hx : x ∈ s) : gauge s x ≤ 1 :=
gauge_le_of_mem zero_le_one $ by rwa one_smul
lemma self_subset_gauge_le_one : s ⊆ {x | gauge s x ≤ 1} := λ x, gauge_le_one_of_mem
lemma convex.gauge_le (hs : convex ℝ s) (h₀ : (0 : E) ∈ s) (absorbs : absorbent ℝ s) (a : ℝ) :
convex ℝ {x | gauge s x ≤ a} :=
begin
by_cases ha : 0 ≤ a,
{ rw gauge_le_eq hs h₀ absorbs ha,
exact convex_Inter (λ i, convex_Inter (λ hi, hs.smul _)) },
{ convert convex_empty,
exact eq_empty_iff_forall_not_mem.2 (λ x hx, ha $ (gauge_nonneg _).trans hx) }
end
lemma balanced.star_convex (hs : balanced ℝ s) : star_convex ℝ 0 s :=
star_convex_zero_iff.2 $ λ x hx a ha₀ ha₁,
hs _ (by rwa real.norm_of_nonneg ha₀) (smul_mem_smul_set hx)
lemma le_gauge_of_not_mem (hs₀ : star_convex ℝ 0 s) (hs₂ : absorbs ℝ s {x}) (hx : x ∉ a • s) :
a ≤ gauge s x :=
begin
rw star_convex_zero_iff at hs₀,
obtain ⟨r, hr, h⟩ := hs₂,
refine le_cInf ⟨r, hr, singleton_subset_iff.1 $ h _ (real.norm_of_nonneg hr.le).ge⟩ _,
rintro b ⟨hb, x, hx', rfl⟩,
refine not_lt.1 (λ hba, hx _),
have ha := hb.trans hba,
refine ⟨(a⁻¹ * b) • x, hs₀ hx' (by positivity) _, _⟩,
{ rw ←div_eq_inv_mul,
exact div_le_one_of_le hba.le ha.le },
{ rw [←mul_smul, mul_inv_cancel_left₀ ha.ne'] }
end
lemma one_le_gauge_of_not_mem (hs₁ : star_convex ℝ 0 s) (hs₂ : absorbs ℝ s {x}) (hx : x ∉ s) :
1 ≤ gauge s x :=
le_gauge_of_not_mem hs₁ hs₂ $ by rwa one_smul
section linear_ordered_field
variables {α : Type*} [linear_ordered_field α] [mul_action_with_zero α ℝ] [ordered_smul α ℝ]
lemma gauge_smul_of_nonneg [mul_action_with_zero α E] [is_scalar_tower α ℝ (set E)] {s : set E}
{a : α} (ha : 0 ≤ a) (x : E) :
gauge s (a • x) = a • gauge s x :=
begin
obtain rfl | ha' := ha.eq_or_lt,
{ rw [zero_smul, gauge_zero, zero_smul] },
rw [gauge_def', gauge_def', ←real.Inf_smul_of_nonneg ha],
congr' 1,
ext r,
simp_rw [set.mem_smul_set, set.mem_sep_iff],
split,
{ rintro ⟨hr, hx⟩,
simp_rw mem_Ioi at ⊢ hr,
rw ←mem_smul_set_iff_inv_smul_mem₀ hr.ne' at hx,
have := smul_pos (inv_pos.2 ha') hr,
refine ⟨a⁻¹ • r, ⟨this, _⟩, smul_inv_smul₀ ha'.ne' _⟩,
rwa [←mem_smul_set_iff_inv_smul_mem₀ this.ne', smul_assoc,
mem_smul_set_iff_inv_smul_mem₀ (inv_ne_zero ha'.ne'), inv_inv] },
{ rintro ⟨r, ⟨hr, hx⟩, rfl⟩,
rw mem_Ioi at ⊢ hr,
rw ←mem_smul_set_iff_inv_smul_mem₀ hr.ne' at hx,
have := smul_pos ha' hr,
refine ⟨this, _⟩,
rw [←mem_smul_set_iff_inv_smul_mem₀ this.ne', smul_assoc],
exact smul_mem_smul_set hx }
end
lemma gauge_smul_left_of_nonneg [mul_action_with_zero α E] [smul_comm_class α ℝ ℝ]
[is_scalar_tower α ℝ ℝ] [is_scalar_tower α ℝ E] {s : set E} {a : α} (ha : 0 ≤ a) :
gauge (a • s) = a⁻¹ • gauge s :=
begin
obtain rfl | ha' := ha.eq_or_lt,
{ rw [inv_zero, zero_smul, gauge_of_subset_zero (zero_smul_set_subset _)] },
ext,
rw [gauge_def', pi.smul_apply, gauge_def', ←real.Inf_smul_of_nonneg (inv_nonneg.2 ha)],
congr' 1,
ext r,
simp_rw [set.mem_smul_set, set.mem_sep_iff],
split,
{ rintro ⟨hr, y, hy, h⟩,
simp_rw [mem_Ioi] at ⊢ hr,
refine ⟨a • r, ⟨smul_pos ha' hr, _⟩, inv_smul_smul₀ ha'.ne' _⟩,
rwa [smul_inv₀, smul_assoc, ←h, inv_smul_smul₀ ha'.ne'] },
{ rintro ⟨r, ⟨hr, hx⟩, rfl⟩,
rw mem_Ioi at ⊢ hr,
have := smul_pos ha' hr,
refine ⟨smul_pos (inv_pos.2 ha') hr, r⁻¹ • x, hx, _⟩,
rw [smul_inv₀, smul_assoc, inv_inv] }
end
lemma gauge_smul_left [module α E] [smul_comm_class α ℝ ℝ] [is_scalar_tower α ℝ ℝ]
[is_scalar_tower α ℝ E] {s : set E} (symmetric : ∀ x ∈ s, -x ∈ s) (a : α) :
gauge (a • s) = |a|⁻¹ • gauge s :=
begin
rw ←gauge_smul_left_of_nonneg (abs_nonneg a),
obtain h | h := abs_choice a,
{ rw h },
{ rw [h, set.neg_smul_set, ←set.smul_set_neg],
congr,
ext y,
refine ⟨symmetric _, λ hy, _⟩,
rw ←neg_neg y,
exact symmetric _ hy },
{ apply_instance }
end
end linear_ordered_field
section is_R_or_C
variables [is_R_or_C 𝕜] [module 𝕜 E] [is_scalar_tower ℝ 𝕜 E]
lemma gauge_norm_smul (hs : balanced 𝕜 s) (r : 𝕜) (x : E) : gauge s (‖r‖ • x) = gauge s (r • x) :=
begin
unfold gauge,
congr' with θ,
rw @is_R_or_C.real_smul_eq_coe_smul 𝕜,
refine and_congr_right (λ hθ, (hs.smul _).mem_smul_iff _),
rw [is_R_or_C.norm_of_real, abs_norm],
end
/-- If `s` is balanced, then the Minkowski functional is ℂ-homogeneous. -/
lemma gauge_smul (hs : balanced 𝕜 s) (r : 𝕜) (x : E) : gauge s (r • x) = ‖r‖ * gauge s x :=
by { rw [←smul_eq_mul, ←gauge_smul_of_nonneg (norm_nonneg r), gauge_norm_smul hs], apply_instance }
end is_R_or_C
section topological_space
variables [topological_space E] [has_continuous_smul ℝ E]
lemma interior_subset_gauge_lt_one (s : set E) : interior s ⊆ {x | gauge s x < 1} :=
begin
intros x hx,
let f : ℝ → E := λ t, t • x,
have hf : continuous f,
{ continuity },
let s' := f ⁻¹' (interior s),
have hs' : is_open s' := hf.is_open_preimage _ is_open_interior,
have one_mem : (1 : ℝ) ∈ s',
{ simpa only [s', f, set.mem_preimage, one_smul] },
obtain ⟨ε, hε₀, hε⟩ := (metric.nhds_basis_closed_ball.1 _).1
(is_open_iff_mem_nhds.1 hs' 1 one_mem),
rw real.closed_ball_eq_Icc at hε,
have hε₁ : 0 < 1 + ε := hε₀.trans (lt_one_add ε),
have : (1 + ε)⁻¹ < 1,
{ rw inv_lt_one_iff,
right,
linarith },
refine (gauge_le_of_mem (inv_nonneg.2 hε₁.le) _).trans_lt this,
rw mem_inv_smul_set_iff₀ hε₁.ne',
exact interior_subset
(hε ⟨(sub_le_self _ hε₀.le).trans ((le_add_iff_nonneg_right _).2 hε₀.le), le_rfl⟩),
end
lemma gauge_lt_one_eq_self_of_open (hs₁ : convex ℝ s) (hs₀ : (0 : E) ∈ s) (hs₂ : is_open s) :
{x | gauge s x < 1} = s :=
begin
refine (gauge_lt_one_subset_self hs₁ ‹_› $ absorbent_nhds_zero $ hs₂.mem_nhds hs₀).antisymm _,
convert interior_subset_gauge_lt_one s,
exact hs₂.interior_eq.symm,
end
lemma gauge_lt_one_of_mem_of_open (hs₁ : convex ℝ s) (hs₀ : (0 : E) ∈ s) (hs₂ : is_open s)
{x : E} (hx : x ∈ s) :
gauge s x < 1 :=
by rwa ←gauge_lt_one_eq_self_of_open hs₁ hs₀ hs₂ at hx
lemma gauge_lt_of_mem_smul (x : E) (ε : ℝ) (hε : 0 < ε) (hs₀ : (0 : E) ∈ s)
(hs₁ : convex ℝ s) (hs₂ : is_open s) (hx : x ∈ ε • s) :
gauge s x < ε :=
begin
have : ε⁻¹ • x ∈ s,
{ rwa ←mem_smul_set_iff_inv_smul_mem₀ hε.ne' },
have h_gauge_lt := gauge_lt_one_of_mem_of_open hs₁ hs₀ hs₂ this,
rwa [gauge_smul_of_nonneg (inv_nonneg.2 hε.le), smul_eq_mul, inv_mul_lt_iff hε, mul_one]
at h_gauge_lt,
apply_instance
end
end topological_space
lemma gauge_add_le (hs : convex ℝ s) (absorbs : absorbent ℝ s) (x y : E) :
gauge s (x + y) ≤ gauge s x + gauge s y :=
begin
refine le_of_forall_pos_lt_add (λ ε hε, _),
obtain ⟨a, ha, ha', hx⟩ := exists_lt_of_gauge_lt absorbs
(lt_add_of_pos_right (gauge s x) (half_pos hε)),
obtain ⟨b, hb, hb', hy⟩ := exists_lt_of_gauge_lt absorbs
(lt_add_of_pos_right (gauge s y) (half_pos hε)),
rw mem_smul_set_iff_inv_smul_mem₀ ha.ne' at hx,
rw mem_smul_set_iff_inv_smul_mem₀ hb.ne' at hy,
suffices : gauge s (x + y) ≤ a + b,
{ linarith },
have hab : 0 < a + b := add_pos ha hb,
apply gauge_le_of_mem hab.le,
have := convex_iff_div.1 hs hx hy ha.le hb.le hab,
rwa [smul_smul, smul_smul, ←mul_div_right_comm, ←mul_div_right_comm, mul_inv_cancel ha.ne',
mul_inv_cancel hb.ne', ←smul_add, one_div, ←mem_smul_set_iff_inv_smul_mem₀ hab.ne'] at this,
end
section is_R_or_C
variables [is_R_or_C 𝕜] [module 𝕜 E] [is_scalar_tower ℝ 𝕜 E]
/-- `gauge s` as a seminorm when `s` is balanced, convex and absorbent. -/
@[simps] def gauge_seminorm (hs₀ : balanced 𝕜 s) (hs₁ : convex ℝ s) (hs₂ : absorbent ℝ s) :
seminorm 𝕜 E :=
seminorm.of (gauge s) (gauge_add_le hs₁ hs₂) (gauge_smul hs₀)
variables {hs₀ : balanced 𝕜 s} {hs₁ : convex ℝ s} {hs₂ : absorbent ℝ s} [topological_space E]
[has_continuous_smul ℝ E]
lemma gauge_seminorm_lt_one_of_open (hs : is_open s) {x : E} (hx : x ∈ s) :
gauge_seminorm hs₀ hs₁ hs₂ x < 1 :=
gauge_lt_one_of_mem_of_open hs₁ hs₂.zero_mem hs hx
lemma gauge_seminorm_ball_one (hs : is_open s) :
(gauge_seminorm hs₀ hs₁ hs₂).ball 0 1 = s :=
begin
rw seminorm.ball_zero_eq,
exact gauge_lt_one_eq_self_of_open hs₁ hs₂.zero_mem hs
end
end is_R_or_C
/-- Any seminorm arises as the gauge of its unit ball. -/
@[simp] protected lemma seminorm.gauge_ball (p : seminorm ℝ E) : gauge (p.ball 0 1) = p :=
begin
ext,
obtain hp | hp := {r : ℝ | 0 < r ∧ x ∈ r • p.ball 0 1}.eq_empty_or_nonempty,
{ rw [gauge, hp, real.Inf_empty],
by_contra,
have hpx : 0 < p x := (map_nonneg _ _).lt_of_ne h,
have hpx₂ : 0 < 2 * p x := mul_pos zero_lt_two hpx,
refine hp.subset ⟨hpx₂, (2 * p x)⁻¹ • x, _, smul_inv_smul₀ hpx₂.ne' _⟩,
rw [p.mem_ball_zero, map_smul_eq_mul, real.norm_eq_abs, abs_of_pos (inv_pos.2 hpx₂),
inv_mul_lt_iff hpx₂, mul_one],
exact lt_mul_of_one_lt_left hpx one_lt_two },
refine is_glb.cInf_eq ⟨λ r, _, λ r hr, le_of_forall_pos_le_add $ λ ε hε, _⟩ hp,
{ rintro ⟨hr, y, hy, rfl⟩,
rw p.mem_ball_zero at hy,
rw [map_smul_eq_mul, real.norm_eq_abs, abs_of_pos hr],
exact mul_le_of_le_one_right hr.le hy.le },
{ have hpε : 0 < p x + ε := by positivity,
refine hr ⟨hpε, (p x + ε)⁻¹ • x, _, smul_inv_smul₀ hpε.ne' _⟩,
rw [p.mem_ball_zero, map_smul_eq_mul, real.norm_eq_abs, abs_of_pos (inv_pos.2 hpε),
inv_mul_lt_iff hpε, mul_one],
exact lt_add_of_pos_right _ hε }
end
lemma seminorm.gauge_seminorm_ball (p : seminorm ℝ E) :
gauge_seminorm (p.balanced_ball_zero 1) (p.convex_ball 0 1)
(p.absorbent_ball_zero zero_lt_one) = p := fun_like.coe_injective p.gauge_ball
end add_comm_group
section norm
variables [seminormed_add_comm_group E] [normed_space ℝ E] {s : set E} {r : ℝ} {x : E}
lemma gauge_unit_ball (x : E) : gauge (metric.ball (0 : E) 1) x = ‖x‖ :=
begin
obtain rfl | hx := eq_or_ne x 0,
{ rw [norm_zero, gauge_zero] },
refine (le_of_forall_pos_le_add $ λ ε hε, _).antisymm _,
{ have : 0 < ‖x‖ + ε := by positivity,
refine gauge_le_of_mem this.le _,
rw [smul_ball this.ne', smul_zero, real.norm_of_nonneg this.le, mul_one, mem_ball_zero_iff],
exact lt_add_of_pos_right _ hε },
refine le_gauge_of_not_mem balanced_ball_zero.star_convex
(absorbent_ball_zero zero_lt_one).absorbs (λ h, _),
obtain hx' | hx' := eq_or_ne (‖x‖) 0,
{ rw hx' at h,
exact hx (zero_smul_set_subset _ h) },
{ rw [mem_smul_set_iff_inv_smul_mem₀ hx', mem_ball_zero_iff, norm_smul, norm_inv, norm_norm,
inv_mul_cancel hx'] at h,
exact lt_irrefl _ h }
end
lemma gauge_ball (hr : 0 < r) (x : E) : gauge (metric.ball (0 : E) r) x = ‖x‖ / r :=
begin
rw [←smul_unit_ball_of_pos hr, gauge_smul_left, pi.smul_apply, gauge_unit_ball, smul_eq_mul,
abs_of_nonneg hr.le, div_eq_inv_mul],
simp_rw [mem_ball_zero_iff, norm_neg],
exact λ _, id,
end
lemma mul_gauge_le_norm (hs : metric.ball (0 : E) r ⊆ s) : r * gauge s x ≤ ‖x‖ :=
begin
obtain hr | hr := le_or_lt r 0,
{ exact (mul_nonpos_of_nonpos_of_nonneg hr $ gauge_nonneg _).trans (norm_nonneg _) },
rw [mul_comm, ←le_div_iff hr, ←gauge_ball hr],
exact gauge_mono (absorbent_ball_zero hr) hs x,
end
end norm
|
b6d41898e4b1ef6996f3d1143199941307cf4d8a | 4d2583807a5ac6caaffd3d7a5f646d61ca85d532 | /src/algebra/homology/homotopy.lean | 374d59b2c34877fc426bcf8c3e097b36b6bce890 | [
"Apache-2.0"
] | permissive | AntoineChambert-Loir/mathlib | 64aabb896129885f12296a799818061bc90da1ff | 07be904260ab6e36a5769680b6012f03a4727134 | refs/heads/master | 1,693,187,631,771 | 1,636,719,886,000 | 1,636,719,886,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 18,306 | lean | /-
Copyright (c) 2021 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import algebra.homology.additive
import tactic.abel
/-!
# Chain homotopies
We define chain homotopies, and prove that homotopic chain maps induce the same map on homology.
-/
universes v u
open_locale classical
noncomputable theory
open category_theory category_theory.limits homological_complex
variables {ι : Type*}
variables {V : Type u} [category.{v} V] [preadditive V]
variables {c : complex_shape ι} {C D E : homological_complex V c}
variables (f g : C ⟶ D) (h k : D ⟶ E) (i : ι)
section
/-- The composition of `C.d i i' ≫ f i' i` if there is some `i'` coming after `i`,
and `0` otherwise. -/
def d_next (i : ι) : (Π i j, C.X i ⟶ D.X j) →+ (C.X i ⟶ D.X i) :=
add_monoid_hom.mk' (λ f, match c.next i with
| none := 0
| some ⟨i',w⟩ := C.d i i' ≫ f i' i
end)
begin
intros f g,
rcases c.next i with _|⟨i',w⟩,
exact (zero_add _).symm,
exact preadditive.comp_add _ _ _ _ _ _,
end
/-- `f i' i` if `i'` comes after `i`, and 0 if there's no such `i'`.
Hopefully there won't be much need for this, except in `d_next_eq_d_from_from_next`
to see that `d_next` factors through `C.d_from i`. -/
def from_next [has_zero_object V] (i : ι) : (Π i j, C.X i ⟶ D.X j) →+ (C.X_next i ⟶ D.X i) :=
add_monoid_hom.mk' (λ f, match c.next i with
| none := 0
| some ⟨i',w⟩ := (C.X_next_iso w).hom ≫ f i' i
end)
begin
intros f g,
rcases c.next i with _|⟨i',w⟩,
exact (zero_add _).symm,
exact preadditive.comp_add _ _ _ _ _ _,
end
lemma d_next_eq_d_from_from_next [has_zero_object V] (f : Π i j, C.X i ⟶ D.X j) (i : ι) :
d_next i f = C.d_from i ≫ from_next i f :=
begin
dsimp [d_next, from_next],
rcases c.next i with ⟨⟩|⟨⟨i', w⟩⟩;
{ dsimp [d_next, from_next], simp },
end
lemma d_next_eq (f : Π i j, C.X i ⟶ D.X j) {i i' : ι} (w : c.rel i i') :
d_next i f = C.d i i' ≫ f i' i :=
begin
dsimp [d_next],
rw c.next_eq_some w,
refl,
end
@[simp] lemma d_next_comp_left (f : C ⟶ D) (g : Π i j, D.X i ⟶ E.X j) (i : ι) :
d_next i (λ i j, f.f i ≫ g i j) = f.f i ≫ d_next i g :=
begin
dsimp [d_next],
rcases c.next i with _|⟨i',w⟩,
{ exact comp_zero.symm, },
{ dsimp [d_next],
simp, },
end
@[simp] lemma d_next_comp_right (f : Π i j, C.X i ⟶ D.X j) (g : D ⟶ E) (i : ι) :
d_next i (λ i j, f i j ≫ g.f j) = d_next i f ≫ g.f i :=
begin
dsimp [d_next],
rcases c.next i with _|⟨i',w⟩,
{ exact zero_comp.symm, },
{ dsimp [d_next],
simp, },
end
/-- The composition of `f j j' ≫ D.d j' j` if there is some `j'` coming before `j`,
and `0` otherwise. -/
def prev_d (j : ι) : (Π i j, C.X i ⟶ D.X j) →+ (C.X j ⟶ D.X j) :=
add_monoid_hom.mk' (λ f, match c.prev j with
| none := 0
| some ⟨j',w⟩ := f j j' ≫ D.d j' j
end)
begin
intros f g,
rcases c.prev j with _|⟨j',w⟩,
exact (zero_add _).symm,
exact preadditive.add_comp _ _ _ _ _ _,
end
/-- `f j j'` if `j'` comes after `j`, and 0 if there's no such `j'`.
Hopefully there won't be much need for this, except in `d_next_eq_d_from_from_next`
to see that `d_next` factors through `C.d_from i`. -/
def to_prev [has_zero_object V] (j : ι) : (Π i j, C.X i ⟶ D.X j) →+ (C.X j ⟶ D.X_prev j) :=
add_monoid_hom.mk' (λ f, match c.prev j with
| none := 0
| some ⟨j',w⟩ := f j j' ≫ (D.X_prev_iso w).inv
end)
begin
intros f g,
rcases c.prev j with _|⟨j',w⟩,
exact (zero_add _).symm,
exact preadditive.add_comp _ _ _ _ _ _,
end
lemma prev_d_eq_to_prev_d_to [has_zero_object V] (f : Π i j, C.X i ⟶ D.X j) (j : ι) :
prev_d j f = to_prev j f ≫ D.d_to j :=
begin
dsimp [prev_d, to_prev],
rcases c.prev j with ⟨⟩|⟨⟨j', w⟩⟩;
{ dsimp [prev_d, to_prev], simp },
end
lemma prev_d_eq (f : Π i j, C.X i ⟶ D.X j) {j j' : ι} (w : c.rel j' j) :
prev_d j f = f j j' ≫ D.d j' j :=
begin
dsimp [prev_d],
rw c.prev_eq_some w,
refl,
end
@[simp] lemma prev_d_comp_left (f : C ⟶ D) (g : Π i j, D.X i ⟶ E.X j) (j : ι) :
prev_d j (λ i j, f.f i ≫ g i j) = f.f j ≫ prev_d j g :=
begin
dsimp [prev_d],
rcases c.prev j with _|⟨j',w⟩,
{ exact comp_zero.symm, },
{ dsimp [prev_d, hom.prev],
simp, },
end
@[simp] lemma to_prev'_comp_right (f : Π i j, C.X i ⟶ D.X j) (g : D ⟶ E) (j : ι) :
prev_d j (λ i j, f i j ≫ g.f j) = prev_d j f ≫ g.f j :=
begin
dsimp [prev_d],
rcases c.prev j with _|⟨j',w⟩,
{ exact zero_comp.symm, },
{ dsimp [prev_d],
simp, },
end
lemma d_next_nat (C D : chain_complex V ℕ) (i : ℕ) (f : Π i j, C.X i ⟶ D.X j) :
d_next i f = C.d i (i-1) ≫ f (i-1) i :=
begin
cases i,
{ dsimp [d_next],
rcases (complex_shape.down ℕ).next 0 with _|⟨j,hj⟩;
dsimp [d_next],
{ rw [C.shape, zero_comp], dsimp, dec_trivial },
{ dsimp at hj, exact (nat.succ_ne_zero _ hj).elim } },
rw d_next_eq, dsimp, refl
end
lemma prev_d_nat (C D : cochain_complex V ℕ) (i : ℕ) (f : Π i j, C.X i ⟶ D.X j) :
prev_d i f = f i (i-1) ≫ D.d (i-1) i :=
begin
cases i,
{ dsimp [prev_d],
rcases (complex_shape.up ℕ).prev 0 with _|⟨j,hj⟩;
dsimp [prev_d],
{ rw [D.shape, comp_zero], dsimp, dec_trivial },
{ dsimp at hj, exact (nat.succ_ne_zero _ hj).elim } },
rw prev_d_eq, dsimp, refl
end
/--
A homotopy `h` between chain maps `f` and `g` consists of components `h i j : C.X i ⟶ D.X j`
which are zero unless `c.rel j i`, satisfying the homotopy condition.
-/
@[ext, nolint has_inhabited_instance]
structure homotopy (f g : C ⟶ D) :=
(hom : Π i j, C.X i ⟶ D.X j)
(zero' : ∀ i j, ¬ c.rel j i → hom i j = 0 . obviously)
(comm : ∀ i, f.f i = d_next i hom + prev_d i hom + g.f i . obviously')
variables {f g}
namespace homotopy
restate_axiom homotopy.zero'
/--
`f` is homotopic to `g` iff `f - g` is homotopic to `0`.
-/
def equiv_sub_zero : homotopy f g ≃ homotopy (f - g) 0 :=
{ to_fun := λ h,
{ hom := λ i j, h.hom i j,
zero' := λ i j w, h.zero _ _ w,
comm := λ i, by simp [h.comm] },
inv_fun := λ h,
{ hom := λ i j, h.hom i j,
zero' := λ i j w, h.zero _ _ w,
comm := λ i, by simpa [sub_eq_iff_eq_add] using h.comm i },
left_inv := by tidy,
right_inv := by tidy, }
/-- Equal chain maps are homotopic. -/
@[simps]
def of_eq (h : f = g) : homotopy f g :=
{ hom := 0,
zero' := λ _ _ _, rfl,
comm := λ _, by simp only [add_monoid_hom.map_zero, zero_add, h] }
/-- Every chain map is homotopic to itself. -/
@[simps, refl]
def refl (f : C ⟶ D) : homotopy f f :=
of_eq (rfl : f = f)
/-- `f` is homotopic to `g` iff `g` is homotopic to `f`. -/
@[simps, symm]
def symm {f g : C ⟶ D} (h : homotopy f g) : homotopy g f :=
{ hom := -h.hom,
zero' := λ i j w, by rw [pi.neg_apply, pi.neg_apply, h.zero i j w, neg_zero],
comm := λ i, by rw [add_monoid_hom.map_neg, add_monoid_hom.map_neg, h.comm, ← neg_add,
← add_assoc, neg_add_self, zero_add] }
/-- homotopy is a transitive relation. -/
@[simps, trans]
def trans {e f g : C ⟶ D} (h : homotopy e f) (k : homotopy f g) : homotopy e g :=
{ hom := h.hom + k.hom,
zero' := λ i j w, by rw [pi.add_apply, pi.add_apply, h.zero i j w, k.zero i j w, zero_add],
comm := λ i, by { rw [add_monoid_hom.map_add, add_monoid_hom.map_add, h.comm, k.comm], abel }, }
/-- homotopy is closed under composition (on the right) -/
@[simps]
def comp_right {e f : C ⟶ D} (h : homotopy e f) (g : D ⟶ E) : homotopy (e ≫ g) (f ≫ g) :=
{ hom := λ i j, h.hom i j ≫ g.f j,
zero' := λ i j w, by rw [h.zero i j w, zero_comp],
comm := λ i, by simp only [h.comm i, d_next_comp_right, preadditive.add_comp,
to_prev'_comp_right, comp_f], }
/-- homotopy is closed under composition (on the left) -/
@[simps]
def comp_left {f g : D ⟶ E} (h : homotopy f g) (e : C ⟶ D) : homotopy (e ≫ f) (e ≫ g) :=
{ hom := λ i j, e.f i ≫ h.hom i j,
zero' := λ i j w, by rw [h.zero i j w, comp_zero],
comm := λ i, by simp only [h.comm i, d_next_comp_left, preadditive.comp_add,
prev_d_comp_left, comp_f], }
/-- homotopy is closed under composition -/
@[simps]
def comp {C₁ C₂ C₃ : homological_complex V c} {f₁ g₁ : C₁ ⟶ C₂} {f₂ g₂ : C₂ ⟶ C₃}
(h₁ : homotopy f₁ g₁) (h₂ : homotopy f₂ g₂) : homotopy (f₁ ≫ f₂) (g₁ ≫ g₂) :=
(h₁.comp_right _).trans (h₂.comp_left _)
/-- a variant of `homotopy.comp_right` useful for dealing with homotopy equivalences. -/
@[simps]
def comp_right_id {f : C ⟶ C} (h : homotopy f (𝟙 C)) (g : C ⟶ D) : homotopy (f ≫ g) g :=
(h.comp_right g).trans (of_eq $ category.id_comp _)
/-- a variant of `homotopy.comp_left` useful for dealing with homotopy equivalences. -/
@[simps]
def comp_left_id {f : D ⟶ D} (h : homotopy f (𝟙 D)) (g : C ⟶ D) : homotopy (g ≫ f) g :=
(h.comp_left g).trans (of_eq $ category.comp_id _)
/-!
`homotopy.mk_inductive` allows us to build a homotopy inductively,
so that as we construct each component, we have available the previous two components,
and the fact that they satisfy the homotopy condition.
To simplify the situation, we only construct homotopies of the form `homotopy e 0`.
`homotopy.equiv_sub_zero` can provide the general case.
Notice however, that this construction does not have particularly good definitional properties:
we have to insert `eq_to_hom` in several places.
Hopefully this is okay in most applications, where we only need to have the existence of some
homotopy.
-/
section mk_inductive
variables {P Q : chain_complex V ℕ}
@[simp] lemma prev_d_chain_complex (f : Π i j, P.X i ⟶ Q.X j) (j : ℕ) :
prev_d j f = f j (j+1) ≫ Q.d _ _ :=
begin
dsimp [prev_d],
simp only [chain_complex.prev],
refl,
end
@[simp] lemma d_next_succ_chain_complex (f : Π i j, P.X i ⟶ Q.X j) (i : ℕ) :
d_next (i+1) f = P.d _ _ ≫ f i (i+1) :=
begin
dsimp [d_next],
simp only [chain_complex.next_nat_succ],
refl,
end
@[simp] lemma d_next_zero_chain_complex (f : Π i j, P.X i ⟶ Q.X j) :
d_next 0 f = 0 :=
begin
dsimp [d_next],
simp only [chain_complex.next_nat_zero],
refl,
end
variables (e : P ⟶ Q)
(zero : P.X 0 ⟶ Q.X 1)
(comm_zero : e.f 0 = zero ≫ Q.d 1 0)
(one : P.X 1 ⟶ Q.X 2)
(comm_one : e.f 1 = P.d 1 0 ≫ zero + one ≫ Q.d 2 1)
(succ : ∀ (n : ℕ)
(p : Σ' (f : P.X n ⟶ Q.X (n+1)) (f' : P.X (n+1) ⟶ Q.X (n+2)),
e.f (n+1) = P.d (n+1) n ≫ f + f' ≫ Q.d (n+2) (n+1)),
Σ' f'' : P.X (n+2) ⟶ Q.X (n+3), e.f (n+2) = P.d (n+2) (n+1) ≫ p.2.1 + f'' ≫ Q.d (n+3) (n+2))
include comm_one comm_zero
/--
An auxiliary construction for `mk_inductive`.
Here we build by induction a family of diagrams,
but don't require at the type level that these successive diagrams actually agree.
They do in fact agree, and we then capture that at the type level (i.e. by constructing a homotopy)
in `mk_inductive`.
At this stage, we don't check the homotopy condition in degree 0,
because it "falls off the end", and is easier to treat using `X_next` and `X_prev`,
which we do in `mk_inductive_aux₂`.
-/
@[simp, nolint unused_arguments]
def mk_inductive_aux₁ :
Π n, Σ' (f : P.X n ⟶ Q.X (n+1)) (f' : P.X (n+1) ⟶ Q.X (n+2)),
e.f (n+1) = P.d (n+1) n ≫ f + f' ≫ Q.d (n+2) (n+1)
| 0 := ⟨zero, one, comm_one⟩
| 1 := ⟨one, (succ 0 ⟨zero, one, comm_one⟩).1, (succ 0 ⟨zero, one, comm_one⟩).2⟩
| (n+2) :=
⟨(mk_inductive_aux₁ (n+1)).2.1,
(succ (n+1) (mk_inductive_aux₁ (n+1))).1,
(succ (n+1) (mk_inductive_aux₁ (n+1))).2⟩
section
variable [has_zero_object V]
/--
An auxiliary construction for `mk_inductive`.
-/
@[simp]
def mk_inductive_aux₂ :
Π n, Σ' (f : P.X_next n ⟶ Q.X n) (f' : P.X n ⟶ Q.X_prev n), e.f n = P.d_from n ≫ f + f' ≫ Q.d_to n
| 0 := ⟨0, zero ≫ (Q.X_prev_iso rfl).inv, by simpa using comm_zero⟩
| (n+1) := let I := mk_inductive_aux₁ e zero comm_zero one comm_one succ n in
⟨(P.X_next_iso rfl).hom ≫ I.1, I.2.1 ≫ (Q.X_prev_iso rfl).inv, by simpa using I.2.2⟩
lemma mk_inductive_aux₃ (i : ℕ) :
(mk_inductive_aux₂ e zero comm_zero one comm_one succ i).2.1 ≫ (Q.X_prev_iso rfl).hom
= (P.X_next_iso rfl).inv ≫ (mk_inductive_aux₂ e zero comm_zero one comm_one succ (i+1)).1 :=
by rcases i with (_|_|i); { dsimp, simp, }
/--
A constructor for a `homotopy e 0`, for `e` a chain map between `ℕ`-indexed chain complexes,
working by induction.
You need to provide the components of the homotopy in degrees 0 and 1,
show that these satisfy the homotopy condition,
and then give a construction of each component,
and the fact that it satisfies the homotopy condition,
using as an inductive hypothesis the data and homotopy condition for the previous two components.
-/
def mk_inductive : homotopy e 0 :=
{ hom := λ i j, if h : i + 1 = j then
(mk_inductive_aux₂ e zero comm_zero one comm_one succ i).2.1 ≫ (Q.X_prev_iso h).hom
else
0,
zero' := λ i j w, by rwa dif_neg,
comm := λ i, begin
dsimp, simp only [add_zero],
convert (mk_inductive_aux₂ e zero comm_zero one comm_one succ i).2.2,
{ rcases i with (_|_|_|i),
{ dsimp,
simp only [d_next_zero_chain_complex, d_from_eq_zero, limits.comp_zero], },
all_goals
{ simp only [d_next_succ_chain_complex],
dsimp,
simp only [category.comp_id, category.assoc, iso.inv_hom_id, d_from_comp_X_next_iso_assoc,
dite_eq_ite, if_true, eq_self_iff_true]}, },
{ cases i,
all_goals
{ simp only [prev_d_chain_complex],
dsimp,
simp only [category.comp_id, category.assoc, iso.inv_hom_id, X_prev_iso_comp_d_to,
dite_eq_ite, if_true, eq_self_iff_true], }, },
end, }
end
end mk_inductive
end homotopy
/--
A homotopy equivalence between two chain complexes consists of a chain map each way,
and homotopies from the compositions to the identity chain maps.
Note that this contains data;
arguably it might be more useful for many applications if we truncated it to a Prop.
-/
structure homotopy_equiv (C D : homological_complex V c) :=
(hom : C ⟶ D)
(inv : D ⟶ C)
(homotopy_hom_inv_id : homotopy (hom ≫ inv) (𝟙 C))
(homotopy_inv_hom_id : homotopy (inv ≫ hom) (𝟙 D))
namespace homotopy_equiv
/-- Any complex is homotopy equivalent to itself. -/
@[refl] def refl (C : homological_complex V c) : homotopy_equiv C C :=
{ hom := 𝟙 C,
inv := 𝟙 C,
homotopy_hom_inv_id := by simp,
homotopy_inv_hom_id := by simp, }
instance : inhabited (homotopy_equiv C C) := ⟨refl C⟩
/-- Being homotopy equivalent is a symmetric relation. -/
@[symm] def symm
{C D : homological_complex V c} (f : homotopy_equiv C D) :
homotopy_equiv D C :=
{ hom := f.inv,
inv := f.hom,
homotopy_hom_inv_id := f.homotopy_inv_hom_id,
homotopy_inv_hom_id := f.homotopy_hom_inv_id, }
/-- Homotopy equivalence is a transitive relation. -/
@[trans] def trans
{C D E : homological_complex V c} (f : homotopy_equiv C D) (g : homotopy_equiv D E) :
homotopy_equiv C E :=
{ hom := f.hom ≫ g.hom,
inv := g.inv ≫ f.inv,
homotopy_hom_inv_id := by simpa using
((g.homotopy_hom_inv_id.comp_right_id f.inv).comp_left f.hom).trans f.homotopy_hom_inv_id,
homotopy_inv_hom_id := by simpa using
((f.homotopy_inv_hom_id.comp_right_id g.hom).comp_left g.inv).trans g.homotopy_inv_hom_id, }
end homotopy_equiv
variables [has_equalizers V] [has_cokernels V] [has_images V] [has_image_maps V]
variable [has_zero_object V]
/--
Homotopic maps induce the same map on homology.
-/
theorem homology_map_eq_of_homotopy (h : homotopy f g) (i : ι) :
(homology_functor V c i).map f = (homology_functor V c i).map g :=
begin
dsimp [homology_functor],
apply eq_of_sub_eq_zero,
ext,
simp only [homology.π_map, comp_zero, preadditive.comp_sub],
dsimp [kernel_subobject_map],
simp_rw [h.comm i],
simp only [zero_add, zero_comp, d_next_eq_d_from_from_next, kernel_subobject_arrow_comp_assoc,
preadditive.comp_add],
rw [←preadditive.sub_comp],
simp only [category_theory.subobject.factor_thru_add_sub_factor_thru_right],
erw [subobject.factor_thru_of_le (D.boundaries_le_cycles i)],
{ simp, },
{ rw [prev_d_eq_to_prev_d_to, ←category.assoc],
apply image_subobject_factors_comp_self, },
end
/-- Homotopy equivalent complexes have isomorphic homologies. -/
def homology_obj_iso_of_homotopy_equiv (f : homotopy_equiv C D) (i : ι) :
(homology_functor V c i).obj C ≅ (homology_functor V c i).obj D :=
{ hom := (homology_functor V c i).map f.hom,
inv := (homology_functor V c i).map f.inv,
hom_inv_id' := begin
rw [←functor.map_comp, homology_map_eq_of_homotopy f.homotopy_hom_inv_id,
category_theory.functor.map_id],
end,
inv_hom_id' := begin
rw [←functor.map_comp, homology_map_eq_of_homotopy f.homotopy_inv_hom_id,
category_theory.functor.map_id],
end, }
end
namespace category_theory
variables {W : Type*} [category W] [preadditive W]
/-- An additive functor takes homotopies to homotopies. -/
@[simps]
def functor.map_homotopy (F : V ⥤ W) [F.additive] {f g : C ⟶ D} (h : homotopy f g) :
homotopy ((F.map_homological_complex c).map f) ((F.map_homological_complex c).map g) :=
{ hom := λ i j, F.map (h.hom i j),
zero' := λ i j w, by { rw [h.zero i j w, F.map_zero], },
comm := λ i, begin
have := h.comm i,
dsimp [d_next, prev_d] at *,
rcases c.next i with _|⟨inext,wn⟩;
rcases c.prev i with _|⟨iprev,wp⟩;
dsimp [d_next, prev_d] at *;
{ intro h,
simp [h] },
end, }
/-- An additive functor preserves homotopy equivalences. -/
@[simps]
def functor.map_homotopy_equiv (F : V ⥤ W) [F.additive] (h : homotopy_equiv C D) :
homotopy_equiv ((F.map_homological_complex c).obj C) ((F.map_homological_complex c).obj D) :=
{ hom := (F.map_homological_complex c).map h.hom,
inv := (F.map_homological_complex c).map h.inv,
homotopy_hom_inv_id := begin
rw [←(F.map_homological_complex c).map_comp, ←(F.map_homological_complex c).map_id],
exact F.map_homotopy h.homotopy_hom_inv_id,
end,
homotopy_inv_hom_id := begin
rw [←(F.map_homological_complex c).map_comp, ←(F.map_homological_complex c).map_id],
exact F.map_homotopy h.homotopy_inv_hom_id,
end }
end category_theory
|
42355c3de1f997f86c0d6acb41c845e6cda59f15 | 63abd62053d479eae5abf4951554e1064a4c45b4 | /src/geometry/manifold/mfderiv.lean | 2208566ad90a7786642168401bb9810168d19596 | [
"Apache-2.0"
] | permissive | Lix0120/mathlib | 0020745240315ed0e517cbf32e738d8f9811dd80 | e14c37827456fc6707f31b4d1d16f1f3a3205e91 | refs/heads/master | 1,673,102,855,024 | 1,604,151,044,000 | 1,604,151,044,000 | 308,930,245 | 0 | 0 | Apache-2.0 | 1,604,164,710,000 | 1,604,163,547,000 | null | UTF-8 | Lean | false | false | 65,813 | lean | /-
Copyright (c) 2020 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Sébastien Gouëzel
-/
import geometry.manifold.basic_smooth_bundle
/-!
# The derivative of functions between smooth manifolds
Let `M` and `M'` be two smooth manifolds with corners over a field `𝕜` (with respective models with
corners `I` on `(E, H)` and `I'` on `(E', H')`), and let `f : M → M'`. We define the
derivative of the function at a point, within a set or along the whole space, mimicking the API
for (Fréchet) derivatives. It is denoted by `mfderiv I I' f x`, where "m" stands for "manifold" and
"f" for "Fréchet" (as in the usual derivative `fderiv 𝕜 f x`).
## Main definitions
* `unique_mdiff_on I s` : predicate saying that, at each point of the set `s`, a function can have
at most one derivative. This technical condition is important when we define
`mfderiv_within` below, as otherwise there is an arbitrary choice in the derivative,
and many properties will fail (for instance the chain rule). This is analogous to
`unique_diff_on 𝕜 s` in a vector space.
Let `f` be a map between smooth manifolds. The following definitions follow the `fderiv` API.
* `mfderiv I I' f x` : the derivative of `f` at `x`, as a continuous linear map from the tangent
space at `x` to the tangent space at `f x`. If the map is not differentiable, this is `0`.
* `mfderiv_within I I' f s x` : the derivative of `f` at `x` within `s`, as a continuous linear map
from the tangent space at `x` to the tangent space at `f x`. If the map is not differentiable
within `s`, this is `0`.
* `mdifferentiable_at I I' f x` : Prop expressing whether `f` is differentiable at `x`.
* `mdifferentiable_within_at 𝕜 f s x` : Prop expressing whether `f` is differentiable within `s`
at `x`.
* `has_mfderiv_at I I' f s x f'` : Prop expressing whether `f` has `f'` as a derivative at `x`.
* `has_mfderiv_within_at I I' f s x f'` : Prop expressing whether `f` has `f'` as a derivative
within `s` at `x`.
* `mdifferentiable_on I I' f s` : Prop expressing that `f` is differentiable on the set `s`.
* `mdifferentiable I I' f` : Prop expressing that `f` is differentiable everywhere.
* `tangent_map I I' f` : the derivative of `f`, as a map from the tangent bundle of `M` to the
tangent bundle of `M'`.
We also establish results on the differential of the identity, constant functions, charts, extended
charts. For functions between vector spaces, we show that the usual notions and the manifold notions
coincide.
## Implementation notes
The tangent bundle is constructed using the machinery of topological fiber bundles, for which one
can define bundled morphisms and construct canonically maps from the total space of one bundle to
the total space of another one. One could use this mechanism to construct directly the derivative
of a smooth map. However, we want to define the derivative of any map (and let it be zero if the map
is not differentiable) to avoid proof arguments everywhere. This means we have to go back to the
details of the definition of the total space of a fiber bundle constructed from core, to cook up a
suitable definition of the derivative. It is the following: at each point, we have a preferred chart
(used to identify the fiber above the point with the model vector space in fiber bundles). Then one
should read the function using these preferred charts at `x` and `f x`, and take the derivative
of `f` in these charts.
Due to the fact that we are working in a model with corners, with an additional embedding `I` of the
model space `H` in the model vector space `E`, the charts taking values in `E` are not the original
charts of the manifold, but those ones composed with `I`, called extended charts. We
define `written_in_ext_chart I I' x f` for the function `f` written in the preferred extended charts.
Then the manifold derivative of `f`, at `x`, is just the usual derivative of
`written_in_ext_chart I I' x f`, at the point `(ext_chart_at I x) x`.
There is a subtelty with respect to continuity: if the function is not continuous, then the image
of a small open set around `x` will not be contained in the source of the preferred chart around
`f x`, which means that when reading `f` in the chart one is losing some information. To avoid this,
we include continuity in the definition of differentiablity (which is reasonable since with any
definition, differentiability implies continuity).
*Warning*: the derivative (even within a subset) is a linear map on the whole tangent space. Suppose
that one is given a smooth submanifold `N`, and a function which is smooth on `N` (i.e., its
restriction to the subtype `N` is smooth). Then, in the whole manifold `M`, the property
`mdifferentiable_on I I' f N` holds. However, `mfderiv_within I I' f N` is not uniquely defined
(what values would one choose for vectors that are transverse to `N`?), which can create issues down
the road. The problem here is that knowing the value of `f` along `N` does not determine the
differential of `f` in all directions. This is in contrast to the case where `N` would be an open
subset, or a submanifold with boundary of maximal dimension, where this issue does not appear.
The predicate `unique_mdiff_on I N` indicates that the derivative along `N` is unique if it exists,
and is an assumption in most statements requiring a form of uniqueness.
On a vector space, the manifold derivative and the usual derivative are equal. This means in
particular that they live on the same space, i.e., the tangent space is defeq to the original vector
space. To get this property is a motivation for our definition of the tangent space as a single
copy of the vector space, instead of more usual definitions such as the space of derivations, or
the space of equivalence classes of smooth curves in the manifold.
## Tags
Derivative, manifold
-/
noncomputable theory
open_locale classical topological_space manifold
open set
universe u
section derivatives_definitions
/-!
### Derivative of maps between manifolds
The derivative of a smooth map `f` between smooth manifold `M` and `M'` at `x` is a bounded linear
map from the tangent space to `M` at `x`, to the tangent space to `M'` at `f x`. Since we defined
the tangent space using one specific chart, the formula for the derivative is written in terms of
this specific chart.
We use the names `mdifferentiable` and `mfderiv`, where the prefix letter `m` means "manifold".
-/
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{H : Type*} [topological_space H] (I : model_with_corners 𝕜 E H)
{M : Type*} [topological_space M] [charted_space H M]
{E' : Type*} [normed_group E'] [normed_space 𝕜 E']
{H' : Type*} [topological_space H'] (I' : model_with_corners 𝕜 E' H')
{M' : Type*} [topological_space M'] [charted_space H' M']
/-- Predicate ensuring that, at a point and within a set, a function can have at most one
derivative. This is expressed using the preferred chart at the considered point. -/
def unique_mdiff_within_at (s : set M) (x : M) :=
unique_diff_within_at 𝕜 ((ext_chart_at I x).symm ⁻¹' s ∩ range I) ((ext_chart_at I x) x)
/-- Predicate ensuring that, at all points of a set, a function can have at most one derivative. -/
def unique_mdiff_on (s : set M) :=
∀x∈s, unique_mdiff_within_at I s x
/-- Conjugating a function to write it in the preferred charts around `x`. The manifold derivative
of `f` will just be the derivative of this conjugated function. -/
@[simp, mfld_simps] def written_in_ext_chart_at (x : M) (f : M → M') : E → E' :=
(ext_chart_at I' (f x)) ∘ f ∘ (ext_chart_at I x).symm
/-- `mdifferentiable_within_at I I' f s x` indicates that the function `f` between manifolds
has a derivative at the point `x` within the set `s`.
This is a generalization of `differentiable_within_at` to manifolds.
We require continuity in the definition, as otherwise points close to `x` in `s` could be sent by
`f` outside of the chart domain around `f x`. Then the chart could do anything to the image points,
and in particular by coincidence `written_in_ext_chart_at I I' x f` could be differentiable, while
this would not mean anything relevant. -/
def mdifferentiable_within_at (f : M → M') (s : set M) (x : M) :=
continuous_within_at f s x ∧
differentiable_within_at 𝕜 (written_in_ext_chart_at I I' x f)
((ext_chart_at I x).symm ⁻¹' s ∩ range I) ((ext_chart_at I x) x)
/-- `mdifferentiable_at I I' f x` indicates that the function `f` between manifolds
has a derivative at the point `x`.
This is a generalization of `differentiable_at` to manifolds.
We require continuity in the definition, as otherwise points close to `x` could be sent by
`f` outside of the chart domain around `f x`. Then the chart could do anything to the image points,
and in particular by coincidence `written_in_ext_chart_at I I' x f` could be differentiable, while
this would not mean anything relevant. -/
def mdifferentiable_at (f : M → M') (x : M) :=
continuous_at f x ∧
differentiable_within_at 𝕜 (written_in_ext_chart_at I I' x f) (range I)
((ext_chart_at I x) x)
/-- `mdifferentiable_on I I' f s` indicates that the function `f` between manifolds
has a derivative within `s` at all points of `s`.
This is a generalization of `differentiable_on` to manifolds. -/
def mdifferentiable_on (f : M → M') (s : set M) :=
∀x ∈ s, mdifferentiable_within_at I I' f s x
/-- `mdifferentiable I I' f` indicates that the function `f` between manifolds
has a derivative everywhere.
This is a generalization of `differentiable` to manifolds. -/
def mdifferentiable (f : M → M') :=
∀x, mdifferentiable_at I I' f x
/-- Prop registering if a local homeomorphism is a local diffeomorphism on its source -/
def local_homeomorph.mdifferentiable (f : local_homeomorph M M') :=
(mdifferentiable_on I I' f f.source) ∧ (mdifferentiable_on I' I f.symm f.target)
variables [smooth_manifold_with_corners I M] [smooth_manifold_with_corners I' M']
/-- `has_mfderiv_within_at I I' f s x f'` indicates that the function `f` between manifolds
has, at the point `x` and within the set `s`, the derivative `f'`. Here, `f'` is a continuous linear
map from the tangent space at `x` to the tangent space at `f x`.
This is a generalization of `has_fderiv_within_at` to manifolds (as indicated by the prefix `m`).
The order of arguments is changed as the type of the derivative `f'` depends on the choice of `x`.
We require continuity in the definition, as otherwise points close to `x` in `s` could be sent by
`f` outside of the chart domain around `f x`. Then the chart could do anything to the image points,
and in particular by coincidence `written_in_ext_chart_at I I' x f` could be differentiable, while
this would not mean anything relevant. -/
def has_mfderiv_within_at (f : M → M') (s : set M) (x : M)
(f' : tangent_space I x →L[𝕜] tangent_space I' (f x)) :=
continuous_within_at f s x ∧
has_fderiv_within_at (written_in_ext_chart_at I I' x f : E → E') f'
((ext_chart_at I x).symm ⁻¹' s ∩ range I) ((ext_chart_at I x) x)
/-- `has_mfderiv_at I I' f x f'` indicates that the function `f` between manifolds
has, at the point `x`, the derivative `f'`. Here, `f'` is a continuous linear
map from the tangent space at `x` to the tangent space at `f x`.
We require continuity in the definition, as otherwise points close to `x` `s` could be sent by
`f` outside of the chart domain around `f x`. Then the chart could do anything to the image points,
and in particular by coincidence `written_in_ext_chart_at I I' x f` could be differentiable, while
this would not mean anything relevant. -/
def has_mfderiv_at (f : M → M') (x : M)
(f' : tangent_space I x →L[𝕜] tangent_space I' (f x)) :=
continuous_at f x ∧
has_fderiv_within_at (written_in_ext_chart_at I I' x f : E → E') f' (range I)
((ext_chart_at I x) x)
/-- Let `f` be a function between two smooth manifolds. Then `mfderiv_within I I' f s x` is the
derivative of `f` at `x` within `s`, as a continuous linear map from the tangent space at `x` to the
tangent space at `f x`. -/
def mfderiv_within (f : M → M') (s : set M) (x : M) : tangent_space I x →L[𝕜] tangent_space I' (f x) :=
if h : mdifferentiable_within_at I I' f s x then
(fderiv_within 𝕜 (written_in_ext_chart_at I I' x f) ((ext_chart_at I x).symm ⁻¹' s ∩ range I)
((ext_chart_at I x) x) : _)
else 0
/-- Let `f` be a function between two smooth manifolds. Then `mfderiv I I' f x` is the derivative of
`f` at `x`, as a continuous linear map from the tangent space at `x` to the tangent space at `f x`. -/
def mfderiv (f : M → M') (x : M) : tangent_space I x →L[𝕜] tangent_space I' (f x) :=
if h : mdifferentiable_at I I' f x then
(fderiv_within 𝕜 (written_in_ext_chart_at I I' x f : E → E') (range I)
((ext_chart_at I x) x) : _)
else 0
/-- The derivative within a set, as a map between the tangent bundles -/
def tangent_map_within (f : M → M') (s : set M) : tangent_bundle I M → tangent_bundle I' M' :=
λp, ⟨f p.1, (mfderiv_within I I' f s p.1 : tangent_space I p.1 → tangent_space I' (f p.1)) p.2⟩
/-- The derivative, as a map between the tangent bundles -/
def tangent_map (f : M → M') : tangent_bundle I M → tangent_bundle I' M' :=
λp, ⟨f p.1, (mfderiv I I' f p.1 : tangent_space I p.1 → tangent_space I' (f p.1)) p.2⟩
end derivatives_definitions
section derivatives_properties
/-! ### Unique differentiability sets in manifolds -/
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{H : Type*} [topological_space H] (I : model_with_corners 𝕜 E H)
{M : Type*} [topological_space M] [charted_space H M] --
{E' : Type*} [normed_group E'] [normed_space 𝕜 E']
{H' : Type*} [topological_space H'] {I' : model_with_corners 𝕜 E' H'}
{M' : Type*} [topological_space M'] [charted_space H' M']
{E'' : Type*} [normed_group E''] [normed_space 𝕜 E'']
{H'' : Type*} [topological_space H''] {I'' : model_with_corners 𝕜 E'' H''}
{M'' : Type*} [topological_space M''] [charted_space H'' M'']
{f f₀ f₁ : M → M'}
{x : M}
{s t : set M}
{g : M' → M''}
{u : set M'}
lemma unique_mdiff_within_at_univ : unique_mdiff_within_at I univ x :=
begin
unfold unique_mdiff_within_at,
simp only [preimage_univ, univ_inter],
exact I.unique_diff _ (mem_range_self _)
end
variable {I}
lemma unique_mdiff_within_at_iff {s : set M} {x : M} :
unique_mdiff_within_at I s x ↔
unique_diff_within_at 𝕜 ((ext_chart_at I x).symm ⁻¹' s ∩ (ext_chart_at I x).target)
((ext_chart_at I x) x) :=
begin
apply unique_diff_within_at_congr,
rw [nhds_within_inter, nhds_within_inter, nhds_within_ext_chart_target_eq]
end
lemma unique_mdiff_within_at.mono (h : unique_mdiff_within_at I s x) (st : s ⊆ t) :
unique_mdiff_within_at I t x :=
unique_diff_within_at.mono h $ inter_subset_inter (preimage_mono st) (subset.refl _)
lemma unique_mdiff_within_at.inter' (hs : unique_mdiff_within_at I s x) (ht : t ∈ 𝓝[s] x) :
unique_mdiff_within_at I (s ∩ t) x :=
begin
rw [unique_mdiff_within_at, ext_chart_preimage_inter_eq],
exact unique_diff_within_at.inter' hs (ext_chart_preimage_mem_nhds_within I x ht)
end
lemma unique_mdiff_within_at.inter (hs : unique_mdiff_within_at I s x) (ht : t ∈ 𝓝 x) :
unique_mdiff_within_at I (s ∩ t) x :=
begin
rw [unique_mdiff_within_at, ext_chart_preimage_inter_eq],
exact unique_diff_within_at.inter hs (ext_chart_preimage_mem_nhds I x ht)
end
lemma is_open.unique_mdiff_within_at (xs : x ∈ s) (hs : is_open s) : unique_mdiff_within_at I s x :=
begin
have := unique_mdiff_within_at.inter (unique_mdiff_within_at_univ I) (mem_nhds_sets hs xs),
rwa univ_inter at this
end
lemma unique_mdiff_on.inter (hs : unique_mdiff_on I s) (ht : is_open t) : unique_mdiff_on I (s ∩ t) :=
λx hx, unique_mdiff_within_at.inter (hs _ hx.1) (mem_nhds_sets ht hx.2)
lemma is_open.unique_mdiff_on (hs : is_open s) : unique_mdiff_on I s :=
λx hx, is_open.unique_mdiff_within_at hx hs
lemma unique_mdiff_on_univ : unique_mdiff_on I (univ : set M) :=
is_open_univ.unique_mdiff_on
/- We name the typeclass variables related to `smooth_manifold_with_corners` structure as they are
necessary in lemmas mentioning the derivative, but not in lemmas about differentiability, so we
want to include them or omit them when necessary. -/
variables [Is : smooth_manifold_with_corners I M] [I's : smooth_manifold_with_corners I' M']
[I''s : smooth_manifold_with_corners I'' M'']
{f' f₀' f₁' : tangent_space I x →L[𝕜] tangent_space I' (f x)}
{g' : tangent_space I' (f x) →L[𝕜] tangent_space I'' (g (f x))}
/-- `unique_mdiff_within_at` achieves its goal: it implies the uniqueness of the derivative. -/
theorem unique_mdiff_within_at.eq (U : unique_mdiff_within_at I s x)
(h : has_mfderiv_within_at I I' f s x f') (h₁ : has_mfderiv_within_at I I' f s x f₁') : f' = f₁' :=
U.eq h.2 h₁.2
theorem unique_mdiff_on.eq (U : unique_mdiff_on I s) (hx : x ∈ s)
(h : has_mfderiv_within_at I I' f s x f') (h₁ : has_mfderiv_within_at I I' f s x f₁') : f' = f₁' :=
unique_mdiff_within_at.eq (U _ hx) h h₁
/-!
### General lemmas on derivatives of functions between manifolds
We mimick the API for functions between vector spaces
-/
lemma mdifferentiable_within_at_iff {f : M → M'} {s : set M} {x : M} :
mdifferentiable_within_at I I' f s x ↔
continuous_within_at f s x ∧
differentiable_within_at 𝕜 (written_in_ext_chart_at I I' x f)
((ext_chart_at I x).target ∩ (ext_chart_at I x).symm ⁻¹' s) ((ext_chart_at I x) x) :=
begin
refine and_congr iff.rfl (exists_congr $ λ f', _),
rw [inter_comm],
simp only [has_fderiv_within_at, nhds_within_inter, nhds_within_ext_chart_target_eq]
end
include Is I's
lemma mfderiv_within_zero_of_not_mdifferentiable_within_at
(h : ¬ mdifferentiable_within_at I I' f s x) : mfderiv_within I I' f s x = 0 :=
by simp only [mfderiv_within, h, dif_neg, not_false_iff]
lemma mfderiv_zero_of_not_mdifferentiable_at
(h : ¬ mdifferentiable_at I I' f x) : mfderiv I I' f x = 0 :=
by simp only [mfderiv, h, dif_neg, not_false_iff]
theorem has_mfderiv_within_at.mono (h : has_mfderiv_within_at I I' f t x f') (hst : s ⊆ t) :
has_mfderiv_within_at I I' f s x f' :=
⟨ continuous_within_at.mono h.1 hst,
has_fderiv_within_at.mono h.2 (inter_subset_inter (preimage_mono hst) (subset.refl _)) ⟩
theorem has_mfderiv_at.has_mfderiv_within_at
(h : has_mfderiv_at I I' f x f') : has_mfderiv_within_at I I' f s x f' :=
⟨ continuous_at.continuous_within_at h.1, has_fderiv_within_at.mono h.2 (inter_subset_right _ _) ⟩
lemma has_mfderiv_within_at.mdifferentiable_within_at (h : has_mfderiv_within_at I I' f s x f') :
mdifferentiable_within_at I I' f s x :=
⟨h.1, ⟨f', h.2⟩⟩
lemma has_mfderiv_at.mdifferentiable_at (h : has_mfderiv_at I I' f x f') :
mdifferentiable_at I I' f x :=
⟨h.1, ⟨f', h.2⟩⟩
@[simp, mfld_simps] lemma has_mfderiv_within_at_univ :
has_mfderiv_within_at I I' f univ x f' ↔ has_mfderiv_at I I' f x f' :=
by simp only [has_mfderiv_within_at, has_mfderiv_at, continuous_within_at_univ] with mfld_simps
theorem has_mfderiv_at_unique
(h₀ : has_mfderiv_at I I' f x f₀') (h₁ : has_mfderiv_at I I' f x f₁') : f₀' = f₁' :=
begin
rw ← has_mfderiv_within_at_univ at h₀ h₁,
exact (unique_mdiff_within_at_univ I).eq h₀ h₁
end
lemma has_mfderiv_within_at_inter' (h : t ∈ 𝓝[s] x) :
has_mfderiv_within_at I I' f (s ∩ t) x f' ↔ has_mfderiv_within_at I I' f s x f' :=
begin
rw [has_mfderiv_within_at, has_mfderiv_within_at, ext_chart_preimage_inter_eq,
has_fderiv_within_at_inter', continuous_within_at_inter' h],
exact ext_chart_preimage_mem_nhds_within I x h,
end
lemma has_mfderiv_within_at_inter (h : t ∈ 𝓝 x) :
has_mfderiv_within_at I I' f (s ∩ t) x f' ↔ has_mfderiv_within_at I I' f s x f' :=
begin
rw [has_mfderiv_within_at, has_mfderiv_within_at, ext_chart_preimage_inter_eq,
has_fderiv_within_at_inter, continuous_within_at_inter h],
exact ext_chart_preimage_mem_nhds I x h,
end
lemma has_mfderiv_within_at.union
(hs : has_mfderiv_within_at I I' f s x f') (ht : has_mfderiv_within_at I I' f t x f') :
has_mfderiv_within_at I I' f (s ∪ t) x f' :=
begin
split,
{ exact continuous_within_at.union hs.1 ht.1 },
{ convert has_fderiv_within_at.union hs.2 ht.2,
simp only [union_inter_distrib_right, preimage_union] }
end
lemma has_mfderiv_within_at.nhds_within (h : has_mfderiv_within_at I I' f s x f')
(ht : s ∈ 𝓝[t] x) : has_mfderiv_within_at I I' f t x f' :=
(has_mfderiv_within_at_inter' ht).1 (h.mono (inter_subset_right _ _))
lemma has_mfderiv_within_at.has_mfderiv_at (h : has_mfderiv_within_at I I' f s x f') (hs : s ∈ 𝓝 x) :
has_mfderiv_at I I' f x f' :=
by rwa [← univ_inter s, has_mfderiv_within_at_inter hs, has_mfderiv_within_at_univ] at h
lemma mdifferentiable_within_at.has_mfderiv_within_at (h : mdifferentiable_within_at I I' f s x) :
has_mfderiv_within_at I I' f s x (mfderiv_within I I' f s x) :=
begin
refine ⟨h.1, _⟩,
simp only [mfderiv_within, h, dif_pos] with mfld_simps,
exact differentiable_within_at.has_fderiv_within_at h.2
end
lemma mdifferentiable_within_at.mfderiv_within (h : mdifferentiable_within_at I I' f s x) :
(mfderiv_within I I' f s x) =
fderiv_within 𝕜 (written_in_ext_chart_at I I' x f : _) ((ext_chart_at I x).symm ⁻¹' s ∩ range I)
((ext_chart_at I x) x) :=
by simp only [mfderiv_within, h, dif_pos]
lemma mdifferentiable_at.has_mfderiv_at (h : mdifferentiable_at I I' f x) :
has_mfderiv_at I I' f x (mfderiv I I' f x) :=
begin
refine ⟨h.1, _⟩,
simp only [mfderiv, h, dif_pos] with mfld_simps,
exact differentiable_within_at.has_fderiv_within_at h.2
end
lemma mdifferentiable_at.mfderiv (h : mdifferentiable_at I I' f x) :
(mfderiv I I' f x) =
fderiv_within 𝕜 (written_in_ext_chart_at I I' x f : _) (range I) ((ext_chart_at I x) x) :=
by simp only [mfderiv, h, dif_pos]
lemma has_mfderiv_at.mfderiv (h : has_mfderiv_at I I' f x f') :
mfderiv I I' f x = f' :=
by { ext, rw has_mfderiv_at_unique h h.mdifferentiable_at.has_mfderiv_at }
lemma has_mfderiv_within_at.mfderiv_within
(h : has_mfderiv_within_at I I' f s x f') (hxs : unique_mdiff_within_at I s x) :
mfderiv_within I I' f s x = f' :=
by { ext, rw hxs.eq h h.mdifferentiable_within_at.has_mfderiv_within_at }
lemma mdifferentiable.mfderiv_within
(h : mdifferentiable_at I I' f x) (hxs : unique_mdiff_within_at I s x) :
mfderiv_within I I' f s x = mfderiv I I' f x :=
begin
apply has_mfderiv_within_at.mfderiv_within _ hxs,
exact h.has_mfderiv_at.has_mfderiv_within_at
end
lemma mfderiv_within_subset (st : s ⊆ t) (hs : unique_mdiff_within_at I s x)
(h : mdifferentiable_within_at I I' f t x) :
mfderiv_within I I' f s x = mfderiv_within I I' f t x :=
((mdifferentiable_within_at.has_mfderiv_within_at h).mono st).mfderiv_within hs
omit Is I's
lemma mdifferentiable_within_at.mono (hst : s ⊆ t)
(h : mdifferentiable_within_at I I' f t x) : mdifferentiable_within_at I I' f s x :=
⟨ continuous_within_at.mono h.1 hst,
differentiable_within_at.mono h.2 (inter_subset_inter (preimage_mono hst) (subset.refl _)) ⟩
lemma mdifferentiable_within_at_univ :
mdifferentiable_within_at I I' f univ x ↔ mdifferentiable_at I I' f x :=
by simp only [mdifferentiable_within_at, mdifferentiable_at, continuous_within_at_univ]
with mfld_simps
lemma mdifferentiable_within_at_inter (ht : t ∈ 𝓝 x) :
mdifferentiable_within_at I I' f (s ∩ t) x ↔ mdifferentiable_within_at I I' f s x :=
begin
rw [mdifferentiable_within_at, mdifferentiable_within_at, ext_chart_preimage_inter_eq,
differentiable_within_at_inter, continuous_within_at_inter ht],
exact ext_chart_preimage_mem_nhds I x ht
end
lemma mdifferentiable_within_at_inter' (ht : t ∈ 𝓝[s] x) :
mdifferentiable_within_at I I' f (s ∩ t) x ↔ mdifferentiable_within_at I I' f s x :=
begin
rw [mdifferentiable_within_at, mdifferentiable_within_at, ext_chart_preimage_inter_eq,
differentiable_within_at_inter', continuous_within_at_inter' ht],
exact ext_chart_preimage_mem_nhds_within I x ht
end
lemma mdifferentiable_at.mdifferentiable_within_at
(h : mdifferentiable_at I I' f x) : mdifferentiable_within_at I I' f s x :=
mdifferentiable_within_at.mono (subset_univ _) (mdifferentiable_within_at_univ.2 h)
lemma mdifferentiable_within_at.mdifferentiable_at
(h : mdifferentiable_within_at I I' f s x) (hs : s ∈ 𝓝 x) : mdifferentiable_at I I' f x :=
begin
have : s = univ ∩ s, by rw univ_inter,
rwa [this, mdifferentiable_within_at_inter hs, mdifferentiable_within_at_univ] at h,
end
lemma mdifferentiable_on.mono
(h : mdifferentiable_on I I' f t) (st : s ⊆ t) : mdifferentiable_on I I' f s :=
λx hx, (h x (st hx)).mono st
lemma mdifferentiable_on_univ :
mdifferentiable_on I I' f univ ↔ mdifferentiable I I' f :=
by { simp only [mdifferentiable_on, mdifferentiable_within_at_univ] with mfld_simps, refl }
lemma mdifferentiable.mdifferentiable_on
(h : mdifferentiable I I' f) : mdifferentiable_on I I' f s :=
(mdifferentiable_on_univ.2 h).mono (subset_univ _)
lemma mdifferentiable_on_of_locally_mdifferentiable_on
(h : ∀x∈s, ∃u, is_open u ∧ x ∈ u ∧ mdifferentiable_on I I' f (s ∩ u)) : mdifferentiable_on I I' f s :=
begin
assume x xs,
rcases h x xs with ⟨t, t_open, xt, ht⟩,
exact (mdifferentiable_within_at_inter (mem_nhds_sets t_open xt)).1 (ht x ⟨xs, xt⟩)
end
include Is I's
@[simp, mfld_simps] lemma mfderiv_within_univ : mfderiv_within I I' f univ = mfderiv I I' f :=
begin
ext x : 1,
simp only [mfderiv_within, mfderiv] with mfld_simps,
rw mdifferentiable_within_at_univ
end
lemma mfderiv_within_inter (ht : t ∈ 𝓝 x) (hs : unique_mdiff_within_at I s x) :
mfderiv_within I I' f (s ∩ t) x = mfderiv_within I I' f s x :=
by rw [mfderiv_within, mfderiv_within, ext_chart_preimage_inter_eq,
mdifferentiable_within_at_inter ht, fderiv_within_inter (ext_chart_preimage_mem_nhds I x ht) hs]
omit Is I's
/-! ### Deriving continuity from differentiability on manifolds -/
theorem has_mfderiv_within_at.continuous_within_at
(h : mdifferentiable_within_at I I' f s x) : continuous_within_at f s x :=
h.1
theorem has_mfderiv_at.continuous_at (h : has_mfderiv_at I I' f x f') :
continuous_at f x :=
h.1
lemma mdifferentiable_within_at.continuous_within_at (h : mdifferentiable_within_at I I' f s x) :
continuous_within_at f s x :=
h.1
lemma mdifferentiable_at.continuous_at (h : mdifferentiable_at I I' f x) : continuous_at f x :=
h.1
lemma mdifferentiable_on.continuous_on (h : mdifferentiable_on I I' f s) : continuous_on f s :=
λx hx, (h x hx).continuous_within_at
lemma mdifferentiable.continuous (h : mdifferentiable I I' f) : continuous f :=
continuous_iff_continuous_at.2 $ λx, (h x).continuous_at
include Is I's
lemma tangent_map_within_subset {p : tangent_bundle I M}
(st : s ⊆ t) (hs : unique_mdiff_within_at I s p.1) (h : mdifferentiable_within_at I I' f t p.1) :
tangent_map_within I I' f s p = tangent_map_within I I' f t p :=
begin
simp only [tangent_map_within] with mfld_simps,
rw mfderiv_within_subset st hs h,
end
lemma tangent_map_within_univ :
tangent_map_within I I' f univ = tangent_map I I' f :=
by { ext p : 1, simp only [tangent_map_within, tangent_map] with mfld_simps }
lemma tangent_map_within_eq_tangent_map {p : tangent_bundle I M}
(hs : unique_mdiff_within_at I s p.1) (h : mdifferentiable_at I I' f p.1) :
tangent_map_within I I' f s p = tangent_map I I' f p :=
begin
rw ← mdifferentiable_within_at_univ at h,
rw ← tangent_map_within_univ,
exact tangent_map_within_subset (subset_univ _) hs h,
end
@[simp, mfld_simps] lemma tangent_map_within_tangent_bundle_proj {p : tangent_bundle I M} :
tangent_bundle.proj I' M' (tangent_map_within I I' f s p) = f (tangent_bundle.proj I M p) := rfl
@[simp, mfld_simps] lemma tangent_map_within_proj {p : tangent_bundle I M} :
(tangent_map_within I I' f s p).1 = f p.1 := rfl
@[simp, mfld_simps] lemma tangent_map_tangent_bundle_proj {p : tangent_bundle I M} :
tangent_bundle.proj I' M' (tangent_map I I' f p) = f (tangent_bundle.proj I M p) := rfl
@[simp, mfld_simps] lemma tangent_map_proj {p : tangent_bundle I M} :
(tangent_map I I' f p).1 = f p.1 := rfl
omit Is I's
/-! ### Congruence lemmas for derivatives on manifolds -/
lemma has_mfderiv_within_at.congr_of_eventually_eq (h : has_mfderiv_within_at I I' f s x f')
(h₁ : f₁ =ᶠ[𝓝[s] x] f) (hx : f₁ x = f x) : has_mfderiv_within_at I I' f₁ s x f' :=
begin
refine ⟨continuous_within_at.congr_of_eventually_eq h.1 h₁ hx, _⟩,
apply has_fderiv_within_at.congr_of_eventually_eq h.2,
{ have : (ext_chart_at I x).symm ⁻¹' {y | f₁ y = f y} ∈
𝓝[(ext_chart_at I x).symm ⁻¹' s ∩ range I] ((ext_chart_at I x) x) :=
ext_chart_preimage_mem_nhds_within I x h₁,
apply filter.mem_sets_of_superset this (λy, _),
simp only [hx] with mfld_simps {contextual := tt} },
{ simp only [hx] with mfld_simps },
end
lemma has_mfderiv_within_at.congr_mono (h : has_mfderiv_within_at I I' f s x f')
(ht : ∀x ∈ t, f₁ x = f x) (hx : f₁ x = f x) (h₁ : t ⊆ s) :
has_mfderiv_within_at I I' f₁ t x f' :=
(h.mono h₁).congr_of_eventually_eq (filter.mem_inf_sets_of_right ht) hx
lemma has_mfderiv_at.congr_of_eventually_eq (h : has_mfderiv_at I I' f x f')
(h₁ : f₁ =ᶠ[𝓝 x] f) : has_mfderiv_at I I' f₁ x f' :=
begin
rw ← has_mfderiv_within_at_univ at ⊢ h,
apply h.congr_of_eventually_eq _ (mem_of_nhds h₁ : _),
rwa nhds_within_univ
end
include Is I's
lemma mdifferentiable_within_at.congr_of_eventually_eq
(h : mdifferentiable_within_at I I' f s x) (h₁ : f₁ =ᶠ[𝓝[s] x] f)
(hx : f₁ x = f x) : mdifferentiable_within_at I I' f₁ s x :=
(h.has_mfderiv_within_at.congr_of_eventually_eq h₁ hx).mdifferentiable_within_at
variables (I I')
lemma filter.eventually_eq.mdifferentiable_within_at_iff
(h₁ : f₁ =ᶠ[𝓝[s] x] f) (hx : f₁ x = f x) :
mdifferentiable_within_at I I' f s x ↔ mdifferentiable_within_at I I' f₁ s x :=
begin
split,
{ assume h,
apply h.congr_of_eventually_eq h₁ hx },
{ assume h,
apply h.congr_of_eventually_eq _ hx.symm,
apply h₁.mono,
intro y,
apply eq.symm }
end
variables {I I'}
lemma mdifferentiable_within_at.congr_mono (h : mdifferentiable_within_at I I' f s x)
(ht : ∀x ∈ t, f₁ x = f x) (hx : f₁ x = f x) (h₁ : t ⊆ s) : mdifferentiable_within_at I I' f₁ t x :=
(has_mfderiv_within_at.congr_mono h.has_mfderiv_within_at ht hx h₁).mdifferentiable_within_at
lemma mdifferentiable_within_at.congr (h : mdifferentiable_within_at I I' f s x)
(ht : ∀x ∈ s, f₁ x = f x) (hx : f₁ x = f x) : mdifferentiable_within_at I I' f₁ s x :=
(has_mfderiv_within_at.congr_mono h.has_mfderiv_within_at ht hx (subset.refl _)).mdifferentiable_within_at
lemma mdifferentiable_on.congr_mono (h : mdifferentiable_on I I' f s) (h' : ∀x ∈ t, f₁ x = f x)
(h₁ : t ⊆ s) : mdifferentiable_on I I' f₁ t :=
λ x hx, (h x (h₁ hx)).congr_mono h' (h' x hx) h₁
lemma mdifferentiable_at.congr_of_eventually_eq (h : mdifferentiable_at I I' f x)
(hL : f₁ =ᶠ[𝓝 x] f) : mdifferentiable_at I I' f₁ x :=
((h.has_mfderiv_at).congr_of_eventually_eq hL).mdifferentiable_at
lemma mdifferentiable_within_at.mfderiv_within_congr_mono (h : mdifferentiable_within_at I I' f s x)
(hs : ∀x ∈ t, f₁ x = f x) (hx : f₁ x = f x) (hxt : unique_mdiff_within_at I t x) (h₁ : t ⊆ s) :
mfderiv_within I I' f₁ t x = (mfderiv_within I I' f s x : _) :=
(has_mfderiv_within_at.congr_mono h.has_mfderiv_within_at hs hx h₁).mfderiv_within hxt
lemma filter.eventually_eq.mfderiv_within_eq (hs : unique_mdiff_within_at I s x)
(hL : f₁ =ᶠ[𝓝[s] x] f) (hx : f₁ x = f x) :
mfderiv_within I I' f₁ s x = (mfderiv_within I I' f s x : _) :=
begin
by_cases h : mdifferentiable_within_at I I' f s x,
{ exact ((h.has_mfderiv_within_at).congr_of_eventually_eq hL hx).mfderiv_within hs },
{ unfold mfderiv_within,
rw [dif_neg h, dif_neg],
rwa ← hL.mdifferentiable_within_at_iff I I' hx }
end
lemma mfderiv_within_congr (hs : unique_mdiff_within_at I s x)
(hL : ∀ x ∈ s, f₁ x = f x) (hx : f₁ x = f x) :
mfderiv_within I I' f₁ s x = (mfderiv_within I I' f s x : _) :=
filter.eventually_eq.mfderiv_within_eq hs (filter.eventually_eq_of_mem (self_mem_nhds_within) hL) hx
lemma tangent_map_within_congr (h : ∀ x ∈ s, f x = f₁ x)
(p : tangent_bundle I M) (hp : p.1 ∈ s) (hs : unique_mdiff_within_at I s p.1) :
tangent_map_within I I' f s p = tangent_map_within I I' f₁ s p :=
begin
simp only [tangent_map_within, h p.fst hp, true_and, eq_self_iff_true, heq_iff_eq,
sigma.mk.inj_iff],
congr' 1,
exact mfderiv_within_congr hs h (h _ hp)
end
lemma filter.eventually_eq.mfderiv_eq (hL : f₁ =ᶠ[𝓝 x] f) :
mfderiv I I' f₁ x = (mfderiv I I' f x : _) :=
begin
have A : f₁ x = f x := (mem_of_nhds hL : _),
rw [← mfderiv_within_univ, ← mfderiv_within_univ],
rw ← nhds_within_univ at hL,
exact hL.mfderiv_within_eq (unique_mdiff_within_at_univ I) A
end
/-! ### Composition lemmas -/
omit Is I's
lemma written_in_ext_chart_comp (h : continuous_within_at f s x) :
{y | written_in_ext_chart_at I I'' x (g ∘ f) y
= ((written_in_ext_chart_at I' I'' (f x) g) ∘ (written_in_ext_chart_at I I' x f)) y}
∈ 𝓝[(ext_chart_at I x).symm ⁻¹' s ∩ range I] ((ext_chart_at I x) x) :=
begin
apply @filter.mem_sets_of_superset _ _
((f ∘ (ext_chart_at I x).symm)⁻¹' (ext_chart_at I' (f x)).source) _
(ext_chart_preimage_mem_nhds_within I x (h.preimage_mem_nhds_within (ext_chart_at_source_mem_nhds _ _))),
mfld_set_tac,
end
variable (x)
include Is I's I''s
theorem has_mfderiv_within_at.comp
(hg : has_mfderiv_within_at I' I'' g u (f x) g') (hf : has_mfderiv_within_at I I' f s x f')
(hst : s ⊆ f ⁻¹' u) :
has_mfderiv_within_at I I'' (g ∘ f) s x (g'.comp f') :=
begin
refine ⟨continuous_within_at.comp hg.1 hf.1 hst, _⟩,
have A : has_fderiv_within_at ((written_in_ext_chart_at I' I'' (f x) g) ∘
(written_in_ext_chart_at I I' x f))
(continuous_linear_map.comp g' f' : E →L[𝕜] E'')
((ext_chart_at I x).symm ⁻¹' s ∩ range (I))
((ext_chart_at I x) x),
{ have : (ext_chart_at I x).symm ⁻¹' (f ⁻¹' (ext_chart_at I' (f x)).source)
∈ 𝓝[(ext_chart_at I x).symm ⁻¹' s ∩ range I] ((ext_chart_at I x) x) :=
(ext_chart_preimage_mem_nhds_within I x
(hf.1.preimage_mem_nhds_within (ext_chart_at_source_mem_nhds _ _))),
unfold has_mfderiv_within_at at *,
rw [← has_fderiv_within_at_inter' this, ← ext_chart_preimage_inter_eq] at hf ⊢,
have : written_in_ext_chart_at I I' x f ((ext_chart_at I x) x)
= (ext_chart_at I' (f x)) (f x),
by simp only with mfld_simps,
rw ← this at hg,
apply has_fderiv_within_at.comp ((ext_chart_at I x) x) hg.2 hf.2 _,
assume y hy,
simp only with mfld_simps at hy,
have : f (((chart_at H x).symm : H → M) (I.symm y)) ∈ u := hst hy.1.1,
simp only [hy, this] with mfld_simps },
apply A.congr_of_eventually_eq (written_in_ext_chart_comp hf.1),
simp only with mfld_simps
end
/-- The chain rule. -/
theorem has_mfderiv_at.comp
(hg : has_mfderiv_at I' I'' g (f x) g') (hf : has_mfderiv_at I I' f x f') :
has_mfderiv_at I I'' (g ∘ f) x (g'.comp f') :=
begin
rw ← has_mfderiv_within_at_univ at *,
exact has_mfderiv_within_at.comp x (hg.mono (subset_univ _)) hf subset_preimage_univ
end
theorem has_mfderiv_at.comp_has_mfderiv_within_at
(hg : has_mfderiv_at I' I'' g (f x) g') (hf : has_mfderiv_within_at I I' f s x f') :
has_mfderiv_within_at I I'' (g ∘ f) s x (g'.comp f') :=
begin
rw ← has_mfderiv_within_at_univ at *,
exact has_mfderiv_within_at.comp x (hg.mono (subset_univ _)) hf subset_preimage_univ
end
lemma mdifferentiable_within_at.comp
(hg : mdifferentiable_within_at I' I'' g u (f x)) (hf : mdifferentiable_within_at I I' f s x)
(h : s ⊆ f ⁻¹' u) : mdifferentiable_within_at I I'' (g ∘ f) s x :=
begin
rcases hf.2 with ⟨f', hf'⟩,
have F : has_mfderiv_within_at I I' f s x f' := ⟨hf.1, hf'⟩,
rcases hg.2 with ⟨g', hg'⟩,
have G : has_mfderiv_within_at I' I'' g u (f x) g' := ⟨hg.1, hg'⟩,
exact (has_mfderiv_within_at.comp x G F h).mdifferentiable_within_at
end
lemma mdifferentiable_at.comp
(hg : mdifferentiable_at I' I'' g (f x)) (hf : mdifferentiable_at I I' f x) :
mdifferentiable_at I I'' (g ∘ f) x :=
(hg.has_mfderiv_at.comp x hf.has_mfderiv_at).mdifferentiable_at
lemma mfderiv_within_comp
(hg : mdifferentiable_within_at I' I'' g u (f x)) (hf : mdifferentiable_within_at I I' f s x)
(h : s ⊆ f ⁻¹' u) (hxs : unique_mdiff_within_at I s x) :
mfderiv_within I I'' (g ∘ f) s x = (mfderiv_within I' I'' g u (f x)).comp (mfderiv_within I I' f s x) :=
begin
apply has_mfderiv_within_at.mfderiv_within _ hxs,
exact has_mfderiv_within_at.comp x hg.has_mfderiv_within_at hf.has_mfderiv_within_at h
end
lemma mfderiv_comp
(hg : mdifferentiable_at I' I'' g (f x)) (hf : mdifferentiable_at I I' f x) :
mfderiv I I'' (g ∘ f) x = (mfderiv I' I'' g (f x)).comp (mfderiv I I' f x) :=
begin
apply has_mfderiv_at.mfderiv,
exact has_mfderiv_at.comp x hg.has_mfderiv_at hf.has_mfderiv_at
end
lemma mdifferentiable_on.comp
(hg : mdifferentiable_on I' I'' g u) (hf : mdifferentiable_on I I' f s) (st : s ⊆ f ⁻¹' u) :
mdifferentiable_on I I'' (g ∘ f) s :=
λx hx, mdifferentiable_within_at.comp x (hg (f x) (st hx)) (hf x hx) st
lemma mdifferentiable.comp
(hg : mdifferentiable I' I'' g) (hf : mdifferentiable I I' f) : mdifferentiable I I'' (g ∘ f) :=
λx, mdifferentiable_at.comp x (hg (f x)) (hf x)
lemma tangent_map_within_comp_at (p : tangent_bundle I M)
(hg : mdifferentiable_within_at I' I'' g u (f p.1)) (hf : mdifferentiable_within_at I I' f s p.1)
(h : s ⊆ f ⁻¹' u) (hps : unique_mdiff_within_at I s p.1) :
tangent_map_within I I'' (g ∘ f) s p =
tangent_map_within I' I'' g u (tangent_map_within I I' f s p) :=
begin
simp only [tangent_map_within] with mfld_simps,
rw mfderiv_within_comp p.1 hg hf h hps,
refl
end
lemma tangent_map_comp_at (p : tangent_bundle I M)
(hg : mdifferentiable_at I' I'' g (f p.1)) (hf : mdifferentiable_at I I' f p.1) :
tangent_map I I'' (g ∘ f) p = tangent_map I' I'' g (tangent_map I I' f p) :=
begin
simp only [tangent_map] with mfld_simps,
rw mfderiv_comp p.1 hg hf,
refl
end
lemma tangent_map_comp (hg : mdifferentiable I' I'' g) (hf : mdifferentiable I I' f) :
tangent_map I I'' (g ∘ f) = (tangent_map I' I'' g) ∘ (tangent_map I I' f) :=
by { ext p : 1, exact tangent_map_comp_at _ (hg _) (hf _) }
end derivatives_properties
section specific_functions
/-! ### Differentiability of specific functions -/
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{H : Type*} [topological_space H] (I : model_with_corners 𝕜 E H)
{M : Type*} [topological_space M] [charted_space H M] [smooth_manifold_with_corners I M]
{s : set M} {x : M}
section id
/-! #### Identity -/
lemma has_mfderiv_at_id (x : M) :
has_mfderiv_at I I (@_root_.id M) x (continuous_linear_map.id 𝕜 (tangent_space I x)) :=
begin
refine ⟨continuous_id.continuous_at, _⟩,
have : ∀ᶠ y in 𝓝[range I] ((ext_chart_at I x) x),
((ext_chart_at I x) ∘ (ext_chart_at I x).symm) y = id y,
{ apply filter.mem_sets_of_superset (ext_chart_at_target_mem_nhds_within I x),
mfld_set_tac },
apply has_fderiv_within_at.congr_of_eventually_eq (has_fderiv_within_at_id _ _) this,
simp only with mfld_simps
end
theorem has_mfderiv_within_at_id (s : set M) (x : M) :
has_mfderiv_within_at I I (@_root_.id M) s x (continuous_linear_map.id 𝕜 (tangent_space I x)) :=
(has_mfderiv_at_id I x).has_mfderiv_within_at
lemma mdifferentiable_at_id : mdifferentiable_at I I (@_root_.id M) x :=
(has_mfderiv_at_id I x).mdifferentiable_at
lemma mdifferentiable_within_at_id : mdifferentiable_within_at I I (@_root_.id M) s x :=
(mdifferentiable_at_id I).mdifferentiable_within_at
lemma mdifferentiable_id : mdifferentiable I I (@_root_.id M) :=
λx, mdifferentiable_at_id I
lemma mdifferentiable_on_id : mdifferentiable_on I I (@_root_.id M) s :=
(mdifferentiable_id I).mdifferentiable_on
@[simp, mfld_simps] lemma mfderiv_id :
mfderiv I I (@_root_.id M) x = (continuous_linear_map.id 𝕜 (tangent_space I x)) :=
has_mfderiv_at.mfderiv (has_mfderiv_at_id I x)
lemma mfderiv_within_id (hxs : unique_mdiff_within_at I s x) :
mfderiv_within I I (@_root_.id M) s x = (continuous_linear_map.id 𝕜 (tangent_space I x)) :=
begin
rw mdifferentiable.mfderiv_within (mdifferentiable_at_id I) hxs,
exact mfderiv_id I
end
@[simp, mfld_simps] lemma tangent_map_id : tangent_map I I (id : M → M) = id :=
by { ext1 ⟨x, v⟩, simp [tangent_map] }
lemma tangent_map_within_id {p : tangent_bundle I M}
(hs : unique_mdiff_within_at I s (tangent_bundle.proj I M p)) :
tangent_map_within I I (id : M → M) s p = p :=
begin
simp only [tangent_map_within, id.def],
rw mfderiv_within_id,
{ rcases p, refl },
{ exact hs }
end
end id
section const
/-! #### Constants -/
variables {E' : Type*} [normed_group E'] [normed_space 𝕜 E']
{H' : Type*} [topological_space H'] (I' : model_with_corners 𝕜 E' H')
{M' : Type*} [topological_space M'] [charted_space H' M'] [smooth_manifold_with_corners I' M']
{c : M'}
lemma has_mfderiv_at_const (c : M') (x : M) :
has_mfderiv_at I I' (λy : M, c) x
(0 : tangent_space I x →L[𝕜] tangent_space I' c) :=
begin
refine ⟨continuous_const.continuous_at, _⟩,
have : (ext_chart_at I' c) ∘ (λ (y : M), c) ∘ (ext_chart_at I x).symm =
(λy, (ext_chart_at I' c) c) := rfl,
rw [written_in_ext_chart_at, this],
apply has_fderiv_within_at_const
end
theorem has_mfderiv_within_at_const (c : M') (s : set M) (x : M) :
has_mfderiv_within_at I I' (λy : M, c) s x
(0 : tangent_space I x →L[𝕜] tangent_space I' c) :=
(has_mfderiv_at_const I I' c x).has_mfderiv_within_at
lemma mdifferentiable_at_const : mdifferentiable_at I I' (λy : M, c) x :=
(has_mfderiv_at_const I I' c x).mdifferentiable_at
lemma mdifferentiable_within_at_const : mdifferentiable_within_at I I' (λy : M, c) s x :=
(mdifferentiable_at_const I I').mdifferentiable_within_at
lemma mdifferentiable_const : mdifferentiable I I' (λy : M, c) :=
λx, mdifferentiable_at_const I I'
lemma mdifferentiable_on_const : mdifferentiable_on I I' (λy : M, c) s :=
(mdifferentiable_const I I').mdifferentiable_on
@[simp, mfld_simps] lemma mfderiv_const : mfderiv I I' (λy : M, c) x =
(0 : tangent_space I x →L[𝕜] tangent_space I' c) :=
has_mfderiv_at.mfderiv (has_mfderiv_at_const I I' c x)
lemma mfderiv_within_const (hxs : unique_mdiff_within_at I s x) :
mfderiv_within I I' (λy : M, c) s x =
(0 : tangent_space I x →L[𝕜] tangent_space I' c) :=
begin
rw mdifferentiable.mfderiv_within (mdifferentiable_at_const I I') hxs,
{ exact mfderiv_const I I' },
{ apply_instance }
end
end const
section model_with_corners
/-! #### Model with corners -/
lemma model_with_corners.mdifferentiable :
mdifferentiable I (model_with_corners_self 𝕜 E) I :=
begin
simp only [mdifferentiable, mdifferentiable_at] with mfld_simps,
assume x,
refine ⟨I.continuous.continuous_at, _⟩,
have : differentiable_within_at 𝕜 id (range I) (I x) :=
differentiable_at_id.differentiable_within_at,
apply this.congr,
{ simp only with mfld_simps {contextual := tt} },
{ simp only with mfld_simps }
end
lemma model_with_corners.mdifferentiable_on_symm :
mdifferentiable_on (model_with_corners_self 𝕜 E) I I.symm (range I) :=
begin
simp only [mdifferentiable_on, mdifferentiable_within_at] with mfld_simps,
assume x hx,
refine ⟨I.continuous_symm.continuous_at.continuous_within_at, _⟩,
have : differentiable_within_at 𝕜 id (range I) x := differentiable_at_id.differentiable_within_at,
apply this.congr,
{ simp only with mfld_simps {contextual := tt} },
{ simp only [hx] with mfld_simps }
end
end model_with_corners
section charts
variable {e : local_homeomorph M H}
lemma mdifferentiable_at_atlas (h : e ∈ atlas H M) {x : M} (hx : x ∈ e.source) :
mdifferentiable_at I I e x :=
begin
refine ⟨(e.continuous_on x hx).continuous_at (mem_nhds_sets e.open_source hx), _⟩,
have mem : I ((chart_at H x : M → H) x) ∈
I.symm ⁻¹' ((chart_at H x).symm ≫ₕ e).source ∩ range I,
by simp only [hx] with mfld_simps,
have : (chart_at H x).symm.trans e ∈ times_cont_diff_groupoid ∞ I :=
has_groupoid.compatible _ (chart_mem_atlas H x) h,
have A : times_cont_diff_on 𝕜 ∞
(I ∘ ((chart_at H x).symm.trans e) ∘ I.symm)
(I.symm ⁻¹' ((chart_at H x).symm.trans e).source ∩ range I) :=
this.1,
have B := A.differentiable_on le_top (I ((chart_at H x : M → H) x)) mem,
simp only with mfld_simps at B,
rw [inter_comm, differentiable_within_at_inter] at B,
{ simpa only with mfld_simps },
{ apply mem_nhds_sets (I.continuous_symm _ (local_homeomorph.open_source _)) mem.1 }
end
lemma mdifferentiable_on_atlas (h : e ∈ atlas H M) :
mdifferentiable_on I I e e.source :=
λx hx, (mdifferentiable_at_atlas I h hx).mdifferentiable_within_at
lemma mdifferentiable_at_atlas_symm (h : e ∈ atlas H M) {x : H} (hx : x ∈ e.target) :
mdifferentiable_at I I e.symm x :=
begin
refine ⟨(e.continuous_on_symm x hx).continuous_at (mem_nhds_sets e.open_target hx), _⟩,
have mem : I x ∈ I.symm ⁻¹' (e.symm ≫ₕ chart_at H (e.symm x)).source ∩ range (I),
by simp only [hx] with mfld_simps,
have : e.symm.trans (chart_at H (e.symm x)) ∈ times_cont_diff_groupoid ∞ I :=
has_groupoid.compatible _ h (chart_mem_atlas H _),
have A : times_cont_diff_on 𝕜 ∞
(I ∘ (e.symm.trans (chart_at H (e.symm x))) ∘ I.symm)
(I.symm ⁻¹' (e.symm.trans (chart_at H (e.symm x))).source ∩ range I) :=
this.1,
have B := A.differentiable_on le_top (I x) mem,
simp only with mfld_simps at B,
rw [inter_comm, differentiable_within_at_inter] at B,
{ simpa only with mfld_simps },
{ apply (mem_nhds_sets (I.continuous_symm _ (local_homeomorph.open_source _)) mem.1) }
end
lemma mdifferentiable_on_atlas_symm (h : e ∈ atlas H M) :
mdifferentiable_on I I e.symm e.target :=
λx hx, (mdifferentiable_at_atlas_symm I h hx).mdifferentiable_within_at
lemma mdifferentiable_of_mem_atlas (h : e ∈ atlas H M) : e.mdifferentiable I I :=
⟨mdifferentiable_on_atlas I h, mdifferentiable_on_atlas_symm I h⟩
lemma mdifferentiable_chart (x : M) : (chart_at H x).mdifferentiable I I :=
mdifferentiable_of_mem_atlas _ (chart_mem_atlas _ _)
/-- The derivative of the chart at a base point is the chart of the tangent bundle, composed with
the identification between the tangent bundle of the model space and the product space. -/
lemma tangent_map_chart {p q : tangent_bundle I M} (h : q.1 ∈ (chart_at H p.1).source) :
tangent_map I I (chart_at H p.1) q =
(equiv.sigma_equiv_prod _ _).symm
((chart_at (model_prod H E) p : tangent_bundle I M → model_prod H E) q) :=
begin
dsimp [tangent_map],
rw mdifferentiable_at.mfderiv,
{ refl },
{ exact mdifferentiable_at_atlas _ (chart_mem_atlas _ _) h }
end
/-- The derivative of the inverse of the chart at a base point is the inverse of the chart of the
tangent bundle, composed with the identification between the tangent bundle of the model space and
the product space. -/
lemma tangent_map_chart_symm {p : tangent_bundle I M} {q : tangent_bundle I H}
(h : q.1 ∈ (chart_at H p.1).target) :
tangent_map I I (chart_at H p.1).symm q =
((chart_at (model_prod H E) p).symm : model_prod H E → tangent_bundle I M)
((equiv.sigma_equiv_prod H E) q) :=
begin
dsimp only [tangent_map],
rw mdifferentiable_at.mfderiv (mdifferentiable_at_atlas_symm _ (chart_mem_atlas _ _) h),
-- a trivial instance is needed after the rewrite, handle it right now.
rotate, { apply_instance },
simp only [chart_at, basic_smooth_bundle_core.chart, subtype.coe_mk, tangent_bundle_core, h,
basic_smooth_bundle_core.to_topological_fiber_bundle_core, equiv.sigma_equiv_prod_apply]
with mfld_simps,
end
end charts
end specific_functions
section mfderiv_fderiv
/-!
### Relations between vector space derivative and manifold derivative
The manifold derivative `mfderiv`, when considered on the model vector space with its trivial
manifold structure, coincides with the usual Frechet derivative `fderiv`. In this section, we prove
this and related statements.
-/
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{E' : Type*} [normed_group E'] [normed_space 𝕜 E']
{f : E → E'} {s : set E} {x : E}
lemma unique_mdiff_within_at_iff_unique_diff_within_at :
unique_mdiff_within_at (model_with_corners_self 𝕜 E) s x ↔ unique_diff_within_at 𝕜 s x :=
by simp only [unique_mdiff_within_at] with mfld_simps
lemma unique_mdiff_on_iff_unique_diff_on :
unique_mdiff_on (model_with_corners_self 𝕜 E) s ↔ unique_diff_on 𝕜 s :=
by simp [unique_mdiff_on, unique_diff_on, unique_mdiff_within_at_iff_unique_diff_within_at]
@[simp, mfld_simps] lemma written_in_ext_chart_model_space :
written_in_ext_chart_at (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') x f = f :=
by { ext y, simp only with mfld_simps }
/-- For maps between vector spaces, `mdifferentiable_within_at` and `fdifferentiable_within_at`
coincide -/
theorem mdifferentiable_within_at_iff_differentiable_within_at :
mdifferentiable_within_at (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') f s x
↔ differentiable_within_at 𝕜 f s x :=
begin
simp only [mdifferentiable_within_at] with mfld_simps,
exact ⟨λH, H.2, λH, ⟨H.continuous_within_at, H⟩⟩
end
/-- For maps between vector spaces, `mdifferentiable_at` and `differentiable_at` coincide -/
theorem mdifferentiable_at_iff_differentiable_at :
mdifferentiable_at (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') f x
↔ differentiable_at 𝕜 f x :=
begin
simp only [mdifferentiable_at, differentiable_within_at_univ] with mfld_simps,
exact ⟨λH, H.2, λH, ⟨H.continuous_at, H⟩⟩
end
/-- For maps between vector spaces, `mdifferentiable_on` and `differentiable_on` coincide -/
theorem mdifferentiable_on_iff_differentiable_on :
mdifferentiable_on (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') f s
↔ differentiable_on 𝕜 f s :=
by simp only [mdifferentiable_on, differentiable_on,
mdifferentiable_within_at_iff_differentiable_within_at]
/-- For maps between vector spaces, `mdifferentiable` and `differentiable` coincide -/
theorem mdifferentiable_iff_differentiable :
mdifferentiable (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') f
↔ differentiable 𝕜 f :=
by simp only [mdifferentiable, differentiable, mdifferentiable_at_iff_differentiable_at]
/-- For maps between vector spaces, `mfderiv_within` and `fderiv_within` coincide -/
theorem mfderiv_within_eq_fderiv_within :
mfderiv_within (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') f s x
= fderiv_within 𝕜 f s x :=
begin
by_cases h : mdifferentiable_within_at (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') f s x,
{ simp only [mfderiv_within, h, dif_pos] with mfld_simps },
{ simp only [mfderiv_within, h, dif_neg, not_false_iff],
rw [mdifferentiable_within_at_iff_differentiable_within_at,
differentiable_within_at] at h,
change ¬(∃(f' : tangent_space (model_with_corners_self 𝕜 E) x →L[𝕜]
tangent_space (model_with_corners_self 𝕜 E') (f x)),
has_fderiv_within_at f f' s x) at h,
simp only [fderiv_within, h, dif_neg, not_false_iff] }
end
/-- For maps between vector spaces, `mfderiv` and `fderiv` coincide -/
theorem mfderiv_eq_fderiv :
mfderiv (model_with_corners_self 𝕜 E) (model_with_corners_self 𝕜 E') f x = fderiv 𝕜 f x :=
begin
rw [← mfderiv_within_univ, ← fderiv_within_univ],
exact mfderiv_within_eq_fderiv_within
end
end mfderiv_fderiv
/-! ### Differentiable local homeomorphisms -/
namespace local_homeomorph.mdifferentiable
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{H : Type*} [topological_space H] {I : model_with_corners 𝕜 E H}
{M : Type*} [topological_space M] [charted_space H M]
{E' : Type*} [normed_group E'] [normed_space 𝕜 E']
{H' : Type*} [topological_space H'] {I' : model_with_corners 𝕜 E' H'}
{M' : Type*} [topological_space M'] [charted_space H' M']
{E'' : Type*} [normed_group E''] [normed_space 𝕜 E'']
{H'' : Type*} [topological_space H''] {I'' : model_with_corners 𝕜 E'' H''}
{M'' : Type*} [topological_space M''] [charted_space H'' M'']
{e : local_homeomorph M M'} (he : e.mdifferentiable I I')
{e' : local_homeomorph M' M''}
include he
lemma symm : e.symm.mdifferentiable I' I :=
⟨he.2, he.1⟩
protected lemma mdifferentiable_at {x : M} (hx : x ∈ e.source) :
mdifferentiable_at I I' e x :=
(he.1 x hx).mdifferentiable_at (mem_nhds_sets e.open_source hx)
lemma mdifferentiable_at_symm {x : M'} (hx : x ∈ e.target) :
mdifferentiable_at I' I e.symm x :=
(he.2 x hx).mdifferentiable_at (mem_nhds_sets e.open_target hx)
variables [smooth_manifold_with_corners I M] [smooth_manifold_with_corners I' M']
[smooth_manifold_with_corners I'' M'']
lemma symm_comp_deriv {x : M} (hx : x ∈ e.source) :
(mfderiv I' I e.symm (e x)).comp (mfderiv I I' e x) =
continuous_linear_map.id 𝕜 (tangent_space I x) :=
begin
have : (mfderiv I I (e.symm ∘ e) x) =
(mfderiv I' I e.symm (e x)).comp (mfderiv I I' e x) :=
mfderiv_comp x (he.mdifferentiable_at_symm (e.map_source hx)) (he.mdifferentiable_at hx),
rw ← this,
have : mfderiv I I (_root_.id : M → M) x = continuous_linear_map.id _ _ := mfderiv_id I,
rw ← this,
apply filter.eventually_eq.mfderiv_eq,
have : e.source ∈ 𝓝 x := mem_nhds_sets e.open_source hx,
exact filter.mem_sets_of_superset this (by mfld_set_tac)
end
lemma comp_symm_deriv {x : M'} (hx : x ∈ e.target) :
(mfderiv I I' e (e.symm x)).comp (mfderiv I' I e.symm x) =
continuous_linear_map.id 𝕜 (tangent_space I' x) :=
he.symm.symm_comp_deriv hx
/-- The derivative of a differentiable local homeomorphism, as a continuous linear equivalence
between the tangent spaces at `x` and `e x`. -/
protected def mfderiv {x : M} (hx : x ∈ e.source) :
tangent_space I x ≃L[𝕜] tangent_space I' (e x) :=
{ inv_fun := (mfderiv I' I e.symm (e x)),
continuous_to_fun := (mfderiv I I' e x).cont,
continuous_inv_fun := (mfderiv I' I e.symm (e x)).cont,
left_inv := λy, begin
have : (continuous_linear_map.id _ _ : tangent_space I x →L[𝕜] tangent_space I x) y = y := rfl,
conv_rhs { rw [← this, ← he.symm_comp_deriv hx] },
refl
end,
right_inv := λy, begin
have : (continuous_linear_map.id 𝕜 _ :
tangent_space I' (e x) →L[𝕜] tangent_space I' (e x)) y = y := rfl,
conv_rhs { rw [← this, ← he.comp_symm_deriv (e.map_source hx)] },
rw e.left_inv hx,
refl
end,
.. mfderiv I I' e x }
lemma mfderiv_bijective {x : M} (hx : x ∈ e.source) :
function.bijective (mfderiv I I' e x) :=
(he.mfderiv hx).bijective
lemma mfderiv_surjective {x : M} (hx : x ∈ e.source) :
function.surjective (mfderiv I I' e x) :=
(he.mfderiv hx).surjective
lemma range_mfderiv_eq_univ {x : M} (hx : x ∈ e.source) :
range (mfderiv I I' e x) = univ :=
(he.mfderiv_surjective hx).range_eq
lemma trans (he': e'.mdifferentiable I' I'') : (e.trans e').mdifferentiable I I'' :=
begin
split,
{ assume x hx,
simp only with mfld_simps at hx,
exact ((he'.mdifferentiable_at hx.2).comp _
(he.mdifferentiable_at hx.1)).mdifferentiable_within_at },
{ assume x hx,
simp only with mfld_simps at hx,
exact ((he.symm.mdifferentiable_at hx.2).comp _
(he'.symm.mdifferentiable_at hx.1)).mdifferentiable_within_at }
end
end local_homeomorph.mdifferentiable
/-! ### Unique derivative sets in manifolds -/
section unique_mdiff
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{H : Type*} [topological_space H] {I : model_with_corners 𝕜 E H}
{M : Type*} [topological_space M] [charted_space H M] [smooth_manifold_with_corners I M]
{E' : Type*} [normed_group E'] [normed_space 𝕜 E']
{H' : Type*} [topological_space H'] {I' : model_with_corners 𝕜 E' H'}
{M' : Type*} [topological_space M'] [charted_space H' M']
{s : set M}
/-- If a set has the unique differential property, then its image under a local
diffeomorphism also has the unique differential property. -/
lemma unique_mdiff_on.unique_mdiff_on_preimage [smooth_manifold_with_corners I' M']
(hs : unique_mdiff_on I s) {e : local_homeomorph M M'} (he : e.mdifferentiable I I') :
unique_mdiff_on I' (e.target ∩ e.symm ⁻¹' s) :=
begin
/- Start from a point `x` in the image, and let `z` be its preimage. Then the unique
derivative property at `x` is expressed through `ext_chart_at I' x`, and the unique
derivative property at `z` is expressed through `ext_chart_at I z`. We will argue that
the composition of these two charts with `e` is a local diffeomorphism in vector spaces,
and therefore preserves the unique differential property thanks to lemma
`has_fderiv_within_at.unique_diff_within_at`, saying that a differentiable function with onto
derivative preserves the unique derivative property.-/
assume x hx,
let z := e.symm x,
have z_source : z ∈ e.source, by simp only [hx.1] with mfld_simps,
have zx : e z = x, by simp only [z, hx.1] with mfld_simps,
let F := ext_chart_at I z,
-- the unique derivative property at `z` is expressed through its preferred chart, that we call `F`.
have B : unique_diff_within_at 𝕜
(F.symm ⁻¹' (s ∩ (e.source ∩ e ⁻¹' ((ext_chart_at I' x).source))) ∩ F.target) (F z),
{ have : unique_mdiff_within_at I s z := hs _ hx.2,
have S : e.source ∩ e ⁻¹' ((ext_chart_at I' x).source) ∈ 𝓝 z,
{ apply mem_nhds_sets,
apply e.continuous_on.preimage_open_of_open e.open_source (ext_chart_at_open_source I' x),
simp only [z_source, zx] with mfld_simps },
have := this.inter S,
rw [unique_mdiff_within_at_iff] at this,
exact this },
-- denote by `G` the change of coordinate, i.e., the composition of the two extended charts and
-- of `e`
let G := F.symm ≫ e.to_local_equiv ≫ (ext_chart_at I' x),
-- `G` is differentiable
have Diff : ((chart_at H z).symm ≫ₕ e ≫ₕ (chart_at H' x)).mdifferentiable I I',
{ have A := mdifferentiable_of_mem_atlas I (chart_mem_atlas H z),
have B := mdifferentiable_of_mem_atlas I' (chart_mem_atlas H' x),
exact A.symm.trans (he.trans B) },
have Mmem : (chart_at H z : M → H) z ∈ ((chart_at H z).symm ≫ₕ e ≫ₕ (chart_at H' x)).source,
by simp only [z_source, zx] with mfld_simps,
have A : differentiable_within_at 𝕜 G (range I) (F z),
{ refine (Diff.mdifferentiable_at Mmem).2.congr (λp hp, _) _;
simp only [G, F] with mfld_simps },
-- let `G'` be its derivative
let G' := fderiv_within 𝕜 G (range I) (F z),
have D₁ : has_fderiv_within_at G G' (range I) (F z) :=
A.has_fderiv_within_at,
have D₂ : has_fderiv_within_at G G'
(F.symm ⁻¹' (s ∩ (e.source ∩ e ⁻¹' ((ext_chart_at I' x).source))) ∩ F.target) (F z) :=
D₁.mono (by mfld_set_tac),
-- The derivative `G'` is onto, as it is the derivative of a local diffeomorphism, the composition
-- of the two charts and of `e`.
have C : dense_range (G' : E → E'),
{ have : G' = mfderiv I I' ((chart_at H z).symm ≫ₕ e ≫ₕ (chart_at H' x)) ((chart_at H z : M → H) z),
by { rw (Diff.mdifferentiable_at Mmem).mfderiv, refl },
rw this,
exact (Diff.mfderiv_surjective Mmem).dense_range },
-- key step: thanks to what we have proved about it, `G` preserves the unique derivative property
have key : unique_diff_within_at 𝕜
(G '' (F.symm ⁻¹' (s ∩ (e.source ∩ e ⁻¹' ((ext_chart_at I' x).source))) ∩ F.target))
(G (F z)) := D₂.unique_diff_within_at B C,
have : G (F z) = (ext_chart_at I' x) x, by { dsimp [G, F], simp only [hx.1] with mfld_simps },
rw this at key,
apply key.mono,
show G '' (F.symm ⁻¹' (s ∩ (e.source ∩ e ⁻¹' ((ext_chart_at I' x).source))) ∩ F.target) ⊆
(ext_chart_at I' x).symm ⁻¹' e.target ∩ (ext_chart_at I' x).symm ⁻¹' (e.symm ⁻¹' s) ∩
range (I'),
rw image_subset_iff,
mfld_set_tac
end
/-- If a set in a manifold has the unique derivative property, then its pullback by any extended
chart, in the vector space, also has the unique derivative property. -/
lemma unique_mdiff_on.unique_diff_on (hs : unique_mdiff_on I s) (x : M) :
unique_diff_on 𝕜 ((ext_chart_at I x).target ∩ ((ext_chart_at I x).symm ⁻¹' s)) :=
begin
-- this is just a reformulation of `unique_mdiff_on.unique_mdiff_on_preimage`, using as `e`
-- the local chart at `x`.
assume z hz,
simp only with mfld_simps at hz,
have : (chart_at H x).mdifferentiable I I := mdifferentiable_chart _ _,
have T := (hs.unique_mdiff_on_preimage this) (I.symm z),
simp only [hz.left.left, hz.left.right, hz.right, unique_mdiff_within_at] with mfld_simps at ⊢ T,
convert T using 1,
rw @preimage_comp _ _ _ _ (chart_at H x).symm,
mfld_set_tac
end
/-- When considering functions between manifolds, this statement shows up often. It entails
the unique differential of the pullback in extended charts of the set where the function can
be read in the charts. -/
lemma unique_mdiff_on.unique_diff_on_inter_preimage (hs : unique_mdiff_on I s) (x : M) (y : M')
{f : M → M'} (hf : continuous_on f s) :
unique_diff_on 𝕜 ((ext_chart_at I x).target
∩ ((ext_chart_at I x).symm ⁻¹' (s ∩ f⁻¹' (ext_chart_at I' y).source))) :=
begin
have : unique_mdiff_on I (s ∩ f ⁻¹' (ext_chart_at I' y).source),
{ assume z hz,
apply (hs z hz.1).inter',
apply (hf z hz.1).preimage_mem_nhds_within,
exact mem_nhds_sets (ext_chart_at_open_source I' y) hz.2 },
exact this.unique_diff_on _
end
variables {F : Type*} [normed_group F] [normed_space 𝕜 F]
(Z : basic_smooth_bundle_core I M F)
/-- In a smooth fiber bundle constructed from core, the preimage under the projection of a set with
unique differential in the basis also has unique differential. -/
lemma unique_mdiff_on.smooth_bundle_preimage (hs : unique_mdiff_on I s) :
unique_mdiff_on (I.prod (model_with_corners_self 𝕜 F))
(Z.to_topological_fiber_bundle_core.proj ⁻¹' s) :=
begin
/- Using a chart (and the fact that unique differentiability is invariant under charts), we
reduce the situation to the model space, where we can use the fact that products respect
unique differentiability. -/
assume p hp,
replace hp : p.fst ∈ s, by simpa only with mfld_simps using hp,
let e₀ := chart_at H p.1,
let e := chart_at (model_prod H F) p,
-- It suffices to prove unique differentiability in a chart
suffices h : unique_mdiff_on (I.prod (model_with_corners_self 𝕜 F))
(e.target ∩ e.symm⁻¹' (Z.to_topological_fiber_bundle_core.proj ⁻¹' s)),
{ have A : unique_mdiff_on (I.prod (model_with_corners_self 𝕜 F)) (e.symm.target ∩
e.symm.symm ⁻¹' (e.target ∩ e.symm⁻¹' (Z.to_topological_fiber_bundle_core.proj ⁻¹' s))),
{ apply h.unique_mdiff_on_preimage,
exact (mdifferentiable_of_mem_atlas _ (chart_mem_atlas _ _)).symm,
apply_instance },
have : p ∈ e.symm.target ∩
e.symm.symm ⁻¹' (e.target ∩ e.symm⁻¹' (Z.to_topological_fiber_bundle_core.proj ⁻¹' s)),
by simp only [e, hp] with mfld_simps,
apply (A _ this).mono,
assume q hq,
simp only [e, local_homeomorph.left_inv _ hq.1] with mfld_simps at hq,
simp only [hq] with mfld_simps },
-- rewrite the relevant set in the chart as a direct product
have : (λ (p : E × F), (I.symm p.1, p.snd)) ⁻¹' e.target ∩
(λ (p : E × F), (I.symm p.1, p.snd)) ⁻¹' (e.symm ⁻¹' (sigma.fst ⁻¹' s)) ∩
((range I).prod univ)
= set.prod (I.symm ⁻¹' (e₀.target ∩ e₀.symm⁻¹' s) ∩ range I) univ,
by mfld_set_tac,
assume q hq,
replace hq : q.1 ∈ (chart_at H p.1).target ∧ ((chart_at H p.1).symm : H → M) q.1 ∈ s,
by simpa only with mfld_simps using hq,
simp only [unique_mdiff_within_at, model_with_corners.prod, preimage_inter, this] with mfld_simps,
-- apply unique differentiability of products to conclude
apply unique_diff_on.prod _ unique_diff_on_univ,
{ simp only [hq] with mfld_simps },
{ assume x hx,
have A : unique_mdiff_on I (e₀.target ∩ e₀.symm⁻¹' s),
{ apply hs.unique_mdiff_on_preimage,
exact (mdifferentiable_of_mem_atlas _ (chart_mem_atlas _ _)),
apply_instance },
simp only [unique_mdiff_on, unique_mdiff_within_at, preimage_inter] with mfld_simps at A,
have B := A (I.symm x) hx.1.1 hx.1.2,
rwa [← preimage_inter, model_with_corners.right_inv _ hx.2] at B }
end
lemma unique_mdiff_on.tangent_bundle_proj_preimage (hs : unique_mdiff_on I s):
unique_mdiff_on I.tangent ((tangent_bundle.proj I M) ⁻¹' s) :=
hs.smooth_bundle_preimage _
end unique_mdiff
|
a0df34552b508b7f1744ad844b5c2895bb4ed3f4 | 9ad8d18fbe5f120c22b5e035bc240f711d2cbd7e | /src/combinatorics/nat_partitions.lean | 41776a27c7d6ee75de19f5221ba8a54d94915f5b | [] | no_license | agusakov/lean_lib | c0e9cc29fc7d2518004e224376adeb5e69b5cc1a | f88d162da2f990b87c4d34f5f46bbca2bbc5948e | refs/heads/master | 1,642,141,461,087 | 1,557,395,798,000 | 1,557,395,798,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 586 | lean | /-
Copyright (c) 2019 Neil Strickland. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Neil Strickland
(This is part of an attempt to formalise some material from
a basic undergraduate combinatorics course.)
We consider the equation x₀ + ... + xₘ = n,
where the variables xᵢ are natural numbers.
The set of solutions bijects with the set of
(n,m) grid paths, so the number of solutions is
(n + m) choose n.
There are various possible modifications, where
we might impose constraints xᵢ ≥ cᵢ for example.
-/ |
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