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8abae453c471deed169cc249d13a2f75fd4a1be0 | 624f6f2ae8b3b1adc5f8f67a365c51d5126be45a | /tests/lean/run/111.lean | 4b3689b086daa3a75fb7e5642eb67127d5ea406d | [
"Apache-2.0"
] | permissive | mhuisi/lean4 | 28d35a4febc2e251c7f05492e13f3b05d6f9b7af | dda44bc47f3e5d024508060dac2bcb59fd12e4c0 | refs/heads/master | 1,621,225,489,283 | 1,585,142,689,000 | 1,585,142,689,000 | 250,590,438 | 0 | 2 | Apache-2.0 | 1,602,443,220,000 | 1,585,327,814,000 | C | UTF-8 | Lean | false | false | 230 | lean | import Init.Lean
new_frontend
open Lean
#check mkNullNode -- Lean.Syntax
#check mkNullNode #[] -- Lean.Syntax
#check @mkNullNode
#check
let f : Array Syntax → Syntax := @mkNullNode;
f #[]
#check let f := @mkNullNode; f #[]
|
898aa01db5a2c2e9713255bc9d93e348f44a5662 | 4fa161becb8ce7378a709f5992a594764699e268 | /src/ring_theory/localization.lean | 3729e936d704b6cf103969e292a7933a3b9b0c68 | [
"Apache-2.0"
] | permissive | laughinggas/mathlib | e4aa4565ae34e46e834434284cb26bd9d67bc373 | 86dcd5cda7a5017c8b3c8876c89a510a19d49aad | refs/heads/master | 1,669,496,232,688 | 1,592,831,995,000 | 1,592,831,995,000 | 274,155,979 | 0 | 0 | Apache-2.0 | 1,592,835,190,000 | 1,592,835,189,000 | null | UTF-8 | Lean | false | false | 33,946 | lean | /-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau, Mario Carneiro, Johan Commelin, Amelia Livingston
-/
import data.equiv.ring
import tactic.ring_exp
import ring_theory.ideal_operations
import group_theory.monoid_localization
/-!
# Localizations of commutative rings
We characterize the localization of a commutative ring `R` at a submonoid `M` up to
isomorphism; that is, a commutative ring `S` is the localization of `R` at `M` iff we can find a
ring homomorphism `f : R →+* S` satisfying 3 properties:
1. For all `y ∈ M`, `f y` is a unit;
2. For all `z : S`, there exists `(x, y) : R × M` such that `z * f y = f x`;
3. For all `x, y : R`, `f x = f y` iff there exists `c ∈ M` such that `x * c = y * c`.
Given such a localization map `f : R →+* S`, we can define the surjection
`localization_map.mk'` sending `(x, y) : R × M` to `f x * (f y)⁻¹`, and
`localization_map.lift`, the homomorphism from `S` induced by a homomorphism from `R` which maps
elements of `M` to invertible elements of the codomain. Similarly, given commutative rings
`P, Q`, a submonoid `T` of `P` and a localization map for `T` from `P` to `Q`, then a homomorphism
`g : R →+* P` such that `g(M) ⊆ T` induces a homomorphism of localizations,
`localization_map.map`, from `S` to `Q`.
We show the localization as a quotient type, defined in `group_theory.monoid_localization` as
`submonoid.localization`, is a `comm_ring` and that the natural ring hom
`of : R →+* localization M` is a localization map.
We prove some lemmas about the `R`-algebra structure of `S`.
When `R` is an integral domain, we define `fraction_map R K` as an abbreviation for
`localization (non_zero_divisors R) K`, the natural map to `R`'s field of fractions.
We show that a `comm_ring` `K` which is the localization of an integral domain `R` at `R \ {0}`
is a field. We use this to show the field of fractions as a quotient type, `fraction_ring`, is
a field.
## Implementation notes
In maths it is natural to reason up to isomorphism, but in Lean we cannot naturally `rewrite` one
structure with an isomorphic one; one way around this is to isolate a predicate characterizing
a structure up to isomorphism, and reason about things that satisfy the predicate.
A ring localization map is defined to be a localization map of the underlying `comm_monoid` (a
`submonoid.localization_map`) which is also a ring hom. To prove most lemmas about a
`localization_map` `f` in this file we invoke the corresponding proof for the underlying
`comm_monoid` localization map `f.to_localization_map`, which can be found in
`group_theory.monoid_localization` and the namespace `submonoid.localization_map`.
To apply a localization map `f` as a function, we use `f.to_map`, as coercions don't work well for
this structure.
To reason about the localization as a quotient type, use `mk_eq_of_mk'` and associated lemmas.
These show the quotient map `mk : R → M → localization M` equals the surjection
`localization_map.mk'` induced by the map `of : localization_map M (localization M)`
(where `of` establishes the localization as a quotient type satisfies the characteristic
predicate). The lemma `mk_eq_of_mk'` hence gives you access to the results in the rest of the file,
which are about the `localization_map.mk'` induced by any localization map.
We use a copy of the localization map `f`'s codomain `S` carrying the data of `f` so that the
`R`-algebra instance on `S` can 'know' the map needed to induce the `R`-algebra structure.
The proof that "a `comm_ring` `K` which is the localization of an integral domain `R` at `R \ {0}`
is a field" is a `def` rather than an `instance`, so if you want to reason about a field of
fractions `K`, assume `[field K]` instead of just `[comm_ring K]`.
## Tags
localization, ring localization, commutative ring localization, characteristic predicate,
commutative ring, field of fractions
-/
variables {R : Type*} [comm_ring R] (M : submonoid R) (S : Type*) [comm_ring S]
{P : Type*} [comm_ring P]
open function
set_option old_structure_cmd true
/-- The type of ring homomorphisms satisfying the characteristic predicate: if `f : R →+* S`
satisfies this predicate, then `S` is isomorphic to the localization of `R` at `M`.
We later define an instance coercing a localization map `f` to its codomain `S` so
that the `R`-algebra instance on `S` can 'know' the map needed to induce the `R`-algebra
structure. -/
@[nolint has_inhabited_instance] structure localization_map
extends ring_hom R S, submonoid.localization_map M S
/-- The ring hom underlying a `localization_map`. -/
add_decl_doc localization_map.to_ring_hom
/-- The `comm_monoid` `localization_map` underlying a `comm_ring` `localization_map`.
See `group_theory.monoid_localization` for its definition. -/
add_decl_doc localization_map.to_localization_map
variables {M S}
namespace ring_hom
/-- Makes a localization map from a `comm_ring` hom satisfying the characteristic predicate. -/
def to_localization_map (f : R →+* S) (H1 : ∀ y : M, is_unit (f y))
(H2 : ∀ z, ∃ x : R × M, z * f x.2 = f x.1) (H3 : ∀ x y, f x = f y ↔ ∃ c : M, x * c = y * c) :
localization_map M S :=
{ map_units' := H1,
surj' := H2,
eq_iff_exists' := H3,
.. f }
end ring_hom
/-- Makes a `comm_ring` localization map from an additive `comm_monoid` localization map of
`comm_ring`s. -/
def submonoid.localization_map.to_ring_localization
(f : submonoid.localization_map M S)
(h : ∀ x y, f.to_map (x + y) = f.to_map x + f.to_map y) :
localization_map M S :=
{ ..ring_hom.mk' f.to_monoid_hom h, ..f }
namespace localization_map
variables (f : localization_map M S)
/-- Short for `to_ring_hom`; used for applying a localization map as a function. -/
abbreviation to_map := f.to_ring_hom
lemma map_units (y : M) : is_unit (f.to_map y) := f.6 y
lemma surj (z) : ∃ x : R × M, z * f.to_map x.2 = f.to_map x.1 := f.7 z
lemma eq_iff_exists {x y} : f.to_map x = f.to_map y ↔ ∃ c : M, x * c = y * c := f.8 x y
@[ext] lemma ext {f g : localization_map M S}
(h : ∀ x, f.to_map x = g.to_map x) : f = g :=
begin
cases f, cases g,
simp only [] at *,
exact funext h
end
lemma ext_iff {f g : localization_map M S} : f = g ↔ ∀ x, f.to_map x = g.to_map x :=
⟨λ h x, h ▸ rfl, ext⟩
lemma to_map_injective : injective (@localization_map.to_map _ _ M S _) :=
λ _ _ h, ext $ ring_hom.ext_iff.1 h
/-- Given `a : S`, `S` a localization of `R`, `is_integer a` iff `a` is in the image of
the localization map from `R` to `S`. -/
def is_integer (a : S) : Prop := a ∈ set.range f.to_map
variables {f}
lemma is_integer_add {a b} (ha : f.is_integer a) (hb : f.is_integer b) :
f.is_integer (a + b) :=
begin
rcases ha with ⟨a', ha⟩,
rcases hb with ⟨b', hb⟩,
use a' + b',
rw [f.to_map.map_add, ha, hb]
end
lemma is_integer_mul {a b} (ha : f.is_integer a) (hb : f.is_integer b) :
f.is_integer (a * b) :=
begin
rcases ha with ⟨a', ha⟩,
rcases hb with ⟨b', hb⟩,
use a' * b',
rw [f.to_map.map_mul, ha, hb]
end
lemma is_integer_smul {a : R} {b} (hb : f.is_integer b) :
f.is_integer (f.to_map a * b) :=
begin
rcases hb with ⟨b', hb⟩,
use a * b',
rw [←hb, f.to_map.map_mul]
end
variables (f)
/-- Each element `a : S` has an `M`-multiple which is an integer.
This version multiplies `a` on the right, matching the argument order in `localization_map.surj`.
-/
lemma exists_integer_multiple' (a : S) :
∃ (b : M), is_integer f (a * f.to_map b) :=
let ⟨⟨num, denom⟩, h⟩ := f.surj a in ⟨denom, set.mem_range.mpr ⟨num, h.symm⟩⟩
/-- Each element `a : S` has an `M`-multiple which is an integer.
This version multiplies `a` on the left, matching the argument order in the `has_scalar` instance.
-/
lemma exists_integer_multiple (a : S) :
∃ (b : M), is_integer f (f.to_map b * a) :=
by { simp_rw mul_comm _ a, apply exists_integer_multiple' }
/-- Given `z : S`, `f.to_localization_map.sec z` is defined to be a pair `(x, y) : R × M` such
that `z * f y = f x` (so this lemma is true by definition). -/
lemma sec_spec {f : localization_map M S} (z : S) :
z * f.to_map (f.to_localization_map.sec z).2 = f.to_map (f.to_localization_map.sec z).1 :=
classical.some_spec $ f.surj z
/-- Given `z : S`, `f.to_localization_map.sec z` is defined to be a pair `(x, y) : R × M` such
that `z * f y = f x`, so this lemma is just an application of `S`'s commutativity. -/
lemma sec_spec' {f : localization_map M S} (z : S) :
f.to_map (f.to_localization_map.sec z).1 = f.to_map (f.to_localization_map.sec z).2 * z :=
by rw [mul_comm, sec_spec]
lemma map_right_cancel {x y} {c : M} (h : f.to_map (c * x) = f.to_map (c * y)) :
f.to_map x = f.to_map y :=
f.to_localization_map.map_right_cancel h
lemma map_left_cancel {x y} {c : M} (h : f.to_map (x * c) = f.to_map (y * c)) :
f.to_map x = f.to_map y :=
f.to_localization_map.map_left_cancel h
lemma eq_zero_of_fst_eq_zero {z x} {y : M}
(h : z * f.to_map y = f.to_map x) (hx : x = 0) : z = 0 :=
by rw [hx, f.to_map.map_zero] at h;
exact (is_unit.mul_left_eq_zero_iff_eq_zero (f.map_units y)).1 h
/-- Given a localization map `f : R →+* S`, the surjection sending `(x, y) : R × M` to
`f x * (f y)⁻¹`. -/
noncomputable def mk' (f : localization_map M S) (x : R) (y : M) : S :=
f.to_localization_map.mk' x y
@[simp] lemma mk'_sec (z : S) :
f.mk' (f.to_localization_map.sec z).1 (f.to_localization_map.sec z).2 = z :=
f.to_localization_map.mk'_sec _
lemma mk'_mul (x₁ x₂ : R) (y₁ y₂ : M) :
f.mk' (x₁ * x₂) (y₁ * y₂) = f.mk' x₁ y₁ * f.mk' x₂ y₂ :=
f.to_localization_map.mk'_mul _ _ _ _
lemma mk'_one (x) : f.mk' x (1 : M) = f.to_map x :=
f.to_localization_map.mk'_one _
lemma mk'_spec (x) (y : M) :
f.mk' x y * f.to_map y = f.to_map x :=
f.to_localization_map.mk'_spec _ _
lemma mk'_spec' (x) (y : M) :
f.to_map y * f.mk' x y = f.to_map x :=
f.to_localization_map.mk'_spec' _ _
theorem eq_mk'_iff_mul_eq {x} {y : M} {z} :
z = f.mk' x y ↔ z * f.to_map y = f.to_map x :=
f.to_localization_map.eq_mk'_iff_mul_eq
theorem mk'_eq_iff_eq_mul {x} {y : M} {z} :
f.mk' x y = z ↔ f.to_map x = z * f.to_map y :=
f.to_localization_map.mk'_eq_iff_eq_mul
lemma mk'_eq_iff_eq {x₁ x₂} {y₁ y₂ : M} :
f.mk' x₁ y₁ = f.mk' x₂ y₂ ↔ f.to_map (x₁ * y₂) = f.to_map (x₂ * y₁) :=
f.to_localization_map.mk'_eq_iff_eq
protected lemma eq {a₁ b₁} {a₂ b₂ : M} :
f.mk' a₁ a₂ = f.mk' b₁ b₂ ↔ ∃ c : M, a₁ * b₂ * c = b₁ * a₂ * c :=
f.to_localization_map.eq
lemma eq_iff_eq (g : localization_map M P) {x y} :
f.to_map x = f.to_map y ↔ g.to_map x = g.to_map y :=
f.to_localization_map.eq_iff_eq g.to_localization_map
lemma mk'_eq_iff_mk'_eq (g : localization_map M P) {x₁ x₂}
{y₁ y₂ : M} : f.mk' x₁ y₁ = f.mk' x₂ y₂ ↔ g.mk' x₁ y₁ = g.mk' x₂ y₂ :=
f.to_localization_map.mk'_eq_iff_mk'_eq g.to_localization_map
lemma mk'_eq_of_eq {a₁ b₁ : R} {a₂ b₂ : M} (H : b₁ * a₂ = a₁ * b₂) :
f.mk' a₁ a₂ = f.mk' b₁ b₂ :=
f.to_localization_map.mk'_eq_of_eq H
@[simp] lemma mk'_self {x : R} {hx : x ∈ M} : f.mk' x ⟨x, hx⟩ = 1 :=
f.to_localization_map.mk'_self' _ hx
@[simp] lemma mk'_self' {x : M} : f.mk' x x = 1 :=
f.to_localization_map.mk'_self _
@[simp] lemma mk'_self'' {x : M} : f.mk' x.1 x = 1 :=
f.mk'_self'
lemma mul_mk'_eq_mk'_of_mul (x y : R) (z : M) :
f.to_map x * f.mk' y z = f.mk' (x * y) z :=
f.to_localization_map.mul_mk'_eq_mk'_of_mul _ _ _
lemma mk'_eq_mul_mk'_one (x : R) (y : M) :
f.mk' x y = f.to_map x * f.mk' 1 y :=
(f.to_localization_map.mul_mk'_one_eq_mk' _ _).symm
@[simp] lemma mk'_mul_cancel_left (x : R) (y : M) :
f.mk' (y * x) y = f.to_map x :=
f.to_localization_map.mk'_mul_cancel_left _ _
lemma mk'_mul_cancel_right (x : R) (y : M) :
f.mk' (x * y) y = f.to_map x :=
f.to_localization_map.mk'_mul_cancel_right _ _
lemma is_unit_comp (j : S →+* P) (y : M) :
is_unit (j.comp f.to_map y) :=
f.to_localization_map.is_unit_comp j.to_monoid_hom _
/-- Given a localization map `f : R →+* S` for a submonoid `M ⊆ R` and a map of `comm_ring`s
`g : R →+* P` such that `g(M) ⊆ units P`, `f x = f y → g x = g y` for all `x y : R`. -/
lemma eq_of_eq {g : R →+* P} (hg : ∀ y : M, is_unit (g y)) {x y} (h : f.to_map x = f.to_map y) :
g x = g y :=
@submonoid.localization_map.eq_of_eq _ _ _ _ _ _ _
f.to_localization_map g.to_monoid_hom hg _ _ h
lemma mk'_add (x₁ x₂ : R) (y₁ y₂ : M) :
f.mk' (x₁ * y₂ + x₂ * y₁) (y₁ * y₂) = f.mk' x₁ y₁ + f.mk' x₂ y₂ :=
f.mk'_eq_iff_eq_mul.2 $ eq.symm
begin
rw [mul_comm (_ + _), mul_add, mul_mk'_eq_mk'_of_mul, ←eq_sub_iff_add_eq, mk'_eq_iff_eq_mul,
mul_comm _ (f.to_map _), mul_sub, eq_sub_iff_add_eq, ←eq_sub_iff_add_eq', ←mul_assoc,
←f.to_map.map_mul, mul_mk'_eq_mk'_of_mul, mk'_eq_iff_eq_mul],
simp only [f.to_map.map_add, submonoid.coe_mul, f.to_map.map_mul],
ring_exp,
end
/-- Given a localization map `f : R →+* S` for a submonoid `M ⊆ R` and a map of `comm_ring`s
`g : R →+* P` such that `g y` is invertible for all `y : M`, the homomorphism induced from
`S` to `P` sending `z : S` to `g x * (g y)⁻¹`, where `(x, y) : R × M` are such that
`z = f x * (f y)⁻¹`. -/
noncomputable def lift {g : R →+* P} (hg : ∀ y : M, is_unit (g y)) : S →+* P :=
ring_hom.mk' (@submonoid.localization_map.lift _ _ _ _ _ _ _
f.to_localization_map g.to_monoid_hom hg) $
begin
intros x y,
rw [f.to_localization_map.lift_spec, mul_comm, add_mul, ←sub_eq_iff_eq_add, eq_comm,
f.to_localization_map.lift_spec_mul, mul_comm _ (_ - _), sub_mul, eq_sub_iff_add_eq',
←eq_sub_iff_add_eq, mul_assoc, f.to_localization_map.lift_spec_mul],
show g _ * (g _ * g _) = g _ * (g _ * g _ - g _ * g _),
repeat {rw ←g.map_mul},
rw [←g.map_sub, ←g.map_mul],
apply f.eq_of_eq hg,
erw [f.to_map.map_mul, sec_spec', mul_sub, f.to_map.map_sub],
simp only [f.to_map.map_mul, sec_spec'],
ring_exp,
end
variables {g : R →+* P} (hg : ∀ y : M, is_unit (g y))
/-- Given a localization map `f : R →+* S` for a submonoid `M ⊆ R` and a map of `comm_ring`s
`g : R →* P` such that `g y` is invertible for all `y : M`, the homomorphism induced from
`S` to `P` maps `f x * (f y)⁻¹` to `g x * (g y)⁻¹` for all `x : R, y ∈ M`. -/
lemma lift_mk' (x y) :
f.lift hg (f.mk' x y) = g x * ↑(is_unit.lift_right (g.to_monoid_hom.mrestrict M) hg y)⁻¹ :=
f.to_localization_map.lift_mk' _ _ _
lemma lift_mk'_spec (x v) (y : M) :
f.lift hg (f.mk' x y) = v ↔ g x = g y * v :=
f.to_localization_map.lift_mk'_spec _ _ _ _
@[simp] lemma lift_eq (x : R) :
f.lift hg (f.to_map x) = g x :=
f.to_localization_map.lift_eq _ _
lemma lift_eq_iff {x y : R × M} :
f.lift hg (f.mk' x.1 x.2) = f.lift hg (f.mk' y.1 y.2) ↔ g (x.1 * y.2) = g (y.1 * x.2) :=
f.to_localization_map.lift_eq_iff _
@[simp] lemma lift_comp : (f.lift hg).comp f.to_map = g :=
ring_hom.ext $ monoid_hom.ext_iff.1 $ f.to_localization_map.lift_comp _
@[simp] lemma lift_of_comp (j : S →+* P) :
f.lift (f.is_unit_comp j) = j :=
ring_hom.ext $ monoid_hom.ext_iff.1 $ f.to_localization_map.lift_of_comp j.to_monoid_hom
lemma epic_of_localization_map {j k : S →+* P}
(h : ∀ a, j.comp f.to_map a = k.comp f.to_map a) : j = k :=
ring_hom.ext $ monoid_hom.ext_iff.1 $ @submonoid.localization_map.epic_of_localization_map
_ _ _ _ _ _ _ f.to_localization_map j.to_monoid_hom k.to_monoid_hom h
lemma lift_unique {j : S →+* P}
(hj : ∀ x, j (f.to_map x) = g x) : f.lift hg = j :=
ring_hom.ext $ monoid_hom.ext_iff.1 $ @submonoid.localization_map.lift_unique
_ _ _ _ _ _ _ f.to_localization_map g.to_monoid_hom hg j.to_monoid_hom hj
@[simp] lemma lift_id (x) : f.lift f.map_units x = x :=
f.to_localization_map.lift_id _
/-- Given two localization maps `f : R →+* S, k : R →+* P` for a submonoid `M ⊆ R`,
the hom from `P` to `S` induced by `f` is left inverse to the hom from `S` to `P`
induced by `k`. -/
@[simp] lemma lift_left_inverse {k : localization_map M S} (z : S) :
k.lift f.map_units (f.lift k.map_units z) = z :=
f.to_localization_map.lift_left_inverse _
lemma lift_surjective_iff :
surjective (f.lift hg) ↔ ∀ v : P, ∃ x : R × M, v * g x.2 = g x.1 :=
f.to_localization_map.lift_surjective_iff hg
lemma lift_injective_iff :
injective (f.lift hg) ↔ ∀ x y, f.to_map x = f.to_map y ↔ g x = g y :=
f.to_localization_map.lift_injective_iff hg
variables {T : submonoid P} (hy : ∀ y : M, g y ∈ T) {Q : Type*} [comm_ring Q]
(k : localization_map T Q)
/-- Given a `comm_ring` homomorphism `g : R →+* P` where for submonoids `M ⊆ R, T ⊆ P` we have
`g(M) ⊆ T`, the induced ring homomorphism from the localization of `R` at `M` to the
localization of `P` at `T`: if `f : R →+* S` and `k : P →+* Q` are localization maps for `M`
and `T` respectively, we send `z : S` to `k (g x) * (k (g y))⁻¹`, where `(x, y) : R × M` are
such that `z = f x * (f y)⁻¹`. -/
noncomputable def map : S →+* Q :=
@lift _ _ _ _ _ _ _ f (k.to_map.comp g) $ λ y, k.map_units ⟨g y, hy y⟩
variables {k}
lemma map_eq (x) :
f.map hy k (f.to_map x) = k.to_map (g x) :=
f.lift_eq (λ y, k.map_units ⟨g y, hy y⟩) x
@[simp] lemma map_comp :
(f.map hy k).comp f.to_map = k.to_map.comp g :=
f.lift_comp $ λ y, k.map_units ⟨g y, hy y⟩
lemma map_mk' (x) (y : M) :
f.map hy k (f.mk' x y) = k.mk' (g x) ⟨g y, hy y⟩ :=
@submonoid.localization_map.map_mk' _ _ _ _ _ _ _ f.to_localization_map
g.to_monoid_hom _ hy _ _ k.to_localization_map _ _
@[simp] lemma map_id (z : S) :
f.map (λ y, show ring_hom.id R y ∈ M, from y.2) f z = z :=
f.lift_id _
/-- If `comm_ring` homs `g : R →+* P, l : P →+* A` induce maps of localizations, the composition
of the induced maps equals the map of localizations induced by `l ∘ g`. -/
lemma map_comp_map {A : Type*} [comm_ring A] {U : submonoid A} {W} [comm_ring W]
(j : localization_map U W) {l : P →+* A} (hl : ∀ w : T, l w ∈ U) :
(k.map hl j).comp (f.map hy k) = f.map (λ x, show l.comp g x ∈ U, from hl ⟨g x, hy x⟩) j :=
ring_hom.ext $ monoid_hom.ext_iff.1 $ @submonoid.localization_map.map_comp_map _ _ _ _ _ _ _
f.to_localization_map g.to_monoid_hom _ hy _ _ k.to_localization_map
_ _ _ _ _ j.to_localization_map l.to_monoid_hom hl
/-- If `comm_ring` homs `g : R →+* P, l : P →+* A` induce maps of localizations, the composition
of the induced maps equals the map of localizations induced by `l ∘ g`. -/
lemma map_map {A : Type*} [comm_ring A] {U : submonoid A} {W} [comm_ring W]
(j : localization_map U W) {l : P →+* A} (hl : ∀ w : T, l w ∈ U) (x) :
k.map hl j (f.map hy k x) = f.map (λ x, show l.comp g x ∈ U, from hl ⟨g x, hy x⟩) j x :=
by rw ←f.map_comp_map hy j hl; refl
/-- Given localization maps `f : R →+* S, k : P →+* Q` for submonoids `M, T` respectively, an
isomorphism `j : R ≃+* P` such that `j(M) = T` induces an isomorphism of localizations
`S ≃+* Q`. -/
noncomputable def ring_equiv_of_ring_equiv (k : localization_map T Q) (h : R ≃+* P)
(H : M.map h.to_monoid_hom = T) :
S ≃+* Q :=
(f.to_localization_map.mul_equiv_of_mul_equiv k.to_localization_map H).to_ring_equiv $
(@lift _ _ _ _ _ _ _ f (k.to_map.comp h.to_ring_hom)
(λ y, k.map_units ⟨(h y), H ▸ set.mem_image_of_mem h y.2⟩)).map_add
@[simp] lemma ring_equiv_of_ring_equiv_eq_map_apply {j : R ≃+* P}
(H : M.map j.to_monoid_hom = T) (x) :
f.ring_equiv_of_ring_equiv k j H x =
f.map (λ y : M, show j.to_monoid_hom y ∈ T, from H ▸ set.mem_image_of_mem j y.2) k x := rfl
lemma ring_equiv_of_ring_equiv_eq_map {j : R ≃+* P} (H : M.map j.to_monoid_hom = T) :
(f.ring_equiv_of_ring_equiv k j H).to_monoid_hom =
f.map (λ y : M, show j.to_monoid_hom y ∈ T, from H ▸ set.mem_image_of_mem j y.2) k := rfl
@[simp] lemma ring_equiv_of_ring_equiv_eq {j : R ≃+* P} (H : M.map j.to_monoid_hom = T) (x) :
f.ring_equiv_of_ring_equiv k j H (f.to_map x) = k.to_map (j x) :=
f.to_localization_map.mul_equiv_of_mul_equiv_eq H _
lemma ring_equiv_of_ring_equiv_mk' {j : R ≃+* P} (H : M.map j.to_monoid_hom = T) (x y) :
f.ring_equiv_of_ring_equiv k j H (f.mk' x y) =
k.mk' (j x) ⟨j y, H ▸ set.mem_image_of_mem j y.2⟩ :=
f.to_localization_map.mul_equiv_of_mul_equiv_mk' H _ _
end localization_map
namespace localization
variables {M}
instance : has_add (localization M) :=
⟨λ z w, con.lift_on₂ z w
(λ x y : R × M, mk ((x.2 : R) * y.1 + y.2 * x.1) (x.2 * y.2)) $
λ r1 r2 r3 r4 h1 h2, (con.eq _).2
begin
rw r_eq_r' at h1 h2 ⊢,
cases h1 with t₅ ht₅,
cases h2 with t₆ ht₆,
use t₆ * t₅,
calc ((r1.2 : R) * r2.1 + r2.2 * r1.1) * (r3.2 * r4.2) * (t₆ * t₅) =
(r2.1 * r4.2 * t₆) * (r1.2 * r3.2 * t₅) + (r1.1 * r3.2 * t₅) * (r2.2 * r4.2 * t₆) : by ring
... = (r3.2 * r4.1 + r4.2 * r3.1) * (r1.2 * r2.2) * (t₆ * t₅) : by rw [ht₆, ht₅]; ring
end⟩
instance : has_neg (localization M) :=
⟨λ z, con.lift_on z (λ x : R × M, mk (-x.1) x.2) $
λ r1 r2 h, (con.eq _).2
begin
rw r_eq_r' at h ⊢,
cases h with t ht,
use t,
rw [neg_mul_eq_neg_mul_symm, neg_mul_eq_neg_mul_symm, ht],
ring,
end⟩
instance : has_zero (localization M) :=
⟨mk 0 1⟩
private meta def tac := `[{
intros,
refine quotient.sound' (r_of_eq _),
simp only [prod.snd_mul, prod.fst_mul, submonoid.coe_mul],
ring }]
instance : comm_ring (localization M) :=
{ zero := 0,
one := 1,
add := (+),
mul := (*),
add_assoc := λ m n k, quotient.induction_on₃' m n k (by tac),
zero_add := λ y, quotient.induction_on' y (by tac),
add_zero := λ y, quotient.induction_on' y (by tac),
neg := has_neg.neg,
add_left_neg := λ y, quotient.induction_on' y (by tac),
add_comm := λ y z, quotient.induction_on₂' z y (by tac),
left_distrib := λ m n k, quotient.induction_on₃' m n k (by tac),
right_distrib := λ m n k, quotient.induction_on₃' m n k (by tac),
..localization.comm_monoid M }
variables (M)
/-- Natural hom sending `x : R`, `R` a `comm_ring`, to the equivalence class of
`(x, 1)` in the localization of `R` at a submonoid. -/
def of : localization_map M (localization M) :=
(localization.monoid_of M).to_ring_localization $
λ x y, (con.eq _).2 $ r_of_eq $ by simp [add_comm]
variables {M}
lemma monoid_of_eq_of (x) : (monoid_of M).to_map x = (of M).to_map x := rfl
lemma mk_one_eq_of (x) : mk x 1 = (of M).to_map x := rfl
lemma mk_eq_mk'_apply (x y) : mk x y = (of M).mk' x y :=
mk_eq_monoid_of_mk'_apply _ _
@[simp] lemma mk_eq_mk' : mk = (of M).mk' :=
mk_eq_monoid_of_mk'
variables (f : localization_map M S)
/-- Given a localization map `f : R →+* S` for a submonoid `M`, we get an isomorphism
between the localization of `R` at `M` as a quotient type and `S`. -/
noncomputable def ring_equiv_of_quotient :
localization M ≃+* S :=
(mul_equiv_of_quotient f.to_localization_map).to_ring_equiv $
((of M).lift f.map_units).map_add
variables {f}
@[simp] lemma ring_equiv_of_quotient_apply (x) :
ring_equiv_of_quotient f x = (of M).lift f.map_units x := rfl
@[simp] lemma ring_equiv_of_quotient_mk' (x y) :
ring_equiv_of_quotient f ((of M).mk' x y) = f.mk' x y :=
mul_equiv_of_quotient_mk' _ _
lemma ring_equiv_of_quotient_mk (x y) :
ring_equiv_of_quotient f (mk x y) = f.mk' x y :=
mul_equiv_of_quotient_mk _ _
@[simp] lemma ring_equiv_of_quotient_of (x) :
ring_equiv_of_quotient f ((of M).to_map x) = f.to_map x :=
mul_equiv_of_quotient_monoid_of _
@[simp] lemma ring_equiv_of_quotient_symm_mk' (x y) :
(ring_equiv_of_quotient f).symm (f.mk' x y) = (of M).mk' x y :=
mul_equiv_of_quotient_symm_mk' _ _
lemma ring_equiv_of_quotient_symm_mk (x y) :
(ring_equiv_of_quotient f).symm (f.mk' x y) = mk x y :=
mul_equiv_of_quotient_symm_mk _ _
@[simp] lemma ring_equiv_of_quotient_symm_of (x) :
(ring_equiv_of_quotient f).symm (f.to_map x) = (of M).to_map x :=
mul_equiv_of_quotient_symm_monoid_of _
end localization
variables {M}
namespace localization_map
/-!
### `algebra` section
Defines the `R`-algebra instance on a copy of `S` carrying the data of the localization map
`f` needed to induce the `R`-algebra structure. -/
variables (f : localization_map M S)
/-- We define a copy of the localization map `f`'s codomain `S` carrying the data of `f` so that
the `R`-algebra instance on `S` can 'know' the map needed to induce the `R`-algebra
structure. -/
@[reducible, nolint unused_arguments] def codomain (f : localization_map M S) := S
/-- We use a copy of the localization map `f`'s codomain `S` carrying the data of `f` so that the
`R`-algebra instance on `S` can 'know' the map needed to induce the `R`-algebra structure. -/
instance : algebra R f.codomain := f.to_map.to_algebra
@[simp] lemma of_id (a : R) :
(algebra.of_id R f.codomain) a = f.to_map a :=
rfl
variables (f)
/-- Localization map `f` from `R` to `S` as an `R`-linear map. -/
def lin_coe : R →ₗ[R] f.codomain :=
{ to_fun := f.to_map,
map_add' := f.to_map.map_add,
map_smul' := f.to_map.map_mul }
variables {f}
instance coe_submodules : has_coe (ideal R) (submodule R f.codomain) :=
⟨λ I, submodule.map f.lin_coe I⟩
lemma mem_coe (I : ideal R) {x : S} :
x ∈ (I : submodule R f.codomain) ↔ ∃ y : R, y ∈ I ∧ f.to_map y = x :=
iff.rfl
@[simp] lemma lin_coe_apply {x} : f.lin_coe x = f.to_map x := rfl
end localization_map
variables (R)
/-- The submonoid of non-zero-divisors of a `comm_ring` `R`. -/
def non_zero_divisors : submonoid R :=
{ carrier := {x | ∀ z, z * x = 0 → z = 0},
one_mem' := λ z hz, by rwa mul_one at hz,
mul_mem' := λ x₁ x₂ hx₁ hx₂ z hz,
have z * x₁ * x₂ = 0, by rwa mul_assoc,
hx₁ z $ hx₂ (z * x₁) this }
variables {A : Type*} [integral_domain A]
lemma eq_zero_of_ne_zero_of_mul_eq_zero
{x y : A} (hnx : x ≠ 0) (hxy : y * x = 0) :
y = 0 := or.resolve_right (eq_zero_or_eq_zero_of_mul_eq_zero hxy) hnx
lemma mem_non_zero_divisors_iff_ne_zero {x : A} :
x ∈ non_zero_divisors A ↔ x ≠ 0 :=
⟨λ hm hz, zero_ne_one (hm 1 $ by rw [hz, one_mul]).symm,
λ hnx z, eq_zero_of_ne_zero_of_mul_eq_zero hnx⟩
lemma map_ne_zero_of_mem_non_zero_divisors {B : Type*} [ring B] {g : A →+* B}
(hg : injective g) {x : non_zero_divisors A} : g x ≠ 0 :=
λ h0, mem_non_zero_divisors_iff_ne_zero.1 x.2 $ g.injective_iff.1 hg x h0
lemma map_mem_non_zero_divisors {B : Type*} [integral_domain B] {g : A →+* B}
(hg : injective g) {x : non_zero_divisors A} : g x ∈ non_zero_divisors B :=
λ z hz, eq_zero_of_ne_zero_of_mul_eq_zero
(map_ne_zero_of_mem_non_zero_divisors hg) hz
variables (K : Type*)
/-- Localization map from an integral domain `R` to its field of fractions. -/
@[reducible] def fraction_map [comm_ring K] := localization_map (non_zero_divisors R) K
namespace fraction_map
open localization_map
variables {R K}
lemma to_map_eq_zero_iff [comm_ring K] (φ : fraction_map R K) {x : R} :
x = 0 ↔ φ.to_map x = 0 :=
begin
rw ← φ.to_map.map_zero,
split; intro h,
{ rw h },
{ cases φ.eq_iff_exists.mp h with c hc,
rw zero_mul at hc,
exact c.2 x hc }
end
protected theorem injective [comm_ring K] (φ : fraction_map R K) :
injective φ.to_map :=
φ.to_map.injective_iff.2 (λ _ h, φ.to_map_eq_zero_iff.mpr h)
local attribute [instance] classical.dec_eq
/-- A `comm_ring` `K` which is the localization of an integral domain `R` at `R - {0}` is an
integral domain. -/
def to_integral_domain [comm_ring K] (φ : fraction_map A K) : integral_domain K :=
{ eq_zero_or_eq_zero_of_mul_eq_zero :=
begin
intros z w h,
cases φ.surj z with x hx,
cases φ.surj w with y hy,
have : z * w * φ.to_map y.2 * φ.to_map x.2 = φ.to_map x.1 * φ.to_map y.1, by
rw [mul_assoc z, hy, ←hx]; ac_refl,
erw h at this,
rw [zero_mul, zero_mul, ←φ.to_map.map_mul] at this,
cases eq_zero_or_eq_zero_of_mul_eq_zero (φ.to_map_eq_zero_iff.mpr this.symm) with H H,
{ exact or.inl (φ.eq_zero_of_fst_eq_zero hx H) },
{ exact or.inr (φ.eq_zero_of_fst_eq_zero hy H) },
end,
zero_ne_one := by erw [←φ.to_map.map_zero, ←φ.to_map.map_one];
exact λ h, zero_ne_one (φ.injective h),
..(infer_instance : comm_ring K) }
/-- The inverse of an element in the field of fractions of an integral domain. -/
protected noncomputable def inv [comm_ring K] (φ : fraction_map A K) (z : K) : K :=
if h : z = 0 then 0 else
φ.mk' (φ.to_localization_map.sec z).2 ⟨(φ.to_localization_map.sec z).1,
mem_non_zero_divisors_iff_ne_zero.2 $ λ h0, h $ φ.eq_zero_of_fst_eq_zero (sec_spec z) h0⟩
protected lemma mul_inv_cancel [comm_ring K] (φ : fraction_map A K) (x : K) (hx : x ≠ 0) :
x * φ.inv x = 1 :=
show x * dite _ _ _ = 1, by rw [dif_neg hx,
←is_unit.mul_left_inj (φ.map_units ⟨(φ.to_localization_map.sec x).1,
mem_non_zero_divisors_iff_ne_zero.2 $ λ h0, hx $ φ.eq_zero_of_fst_eq_zero (sec_spec x) h0⟩),
one_mul, mul_assoc, mk'_spec, ←eq_mk'_iff_mul_eq]; exact (φ.mk'_sec x).symm
/-- A `comm_ring` `K` which is the localization of an integral domain `R` at `R - {0}` is a
field. -/
noncomputable def to_field [comm_ring K] (φ : fraction_map A K) : field K :=
{ inv := φ.inv,
mul_inv_cancel := φ.mul_inv_cancel,
inv_zero := dif_pos rfl, ..φ.to_integral_domain }
variables {B : Type*} [integral_domain B] [field K] {L : Type*} [field L]
(f : fraction_map A K) {g : A →+* L}
lemma mk'_eq_div {r s} : f.mk' r s = f.to_map r / f.to_map s :=
f.mk'_eq_iff_eq_mul.2 $ (div_mul_cancel _
(map_ne_zero_of_mem_non_zero_divisors f.injective)).symm
lemma is_unit_map_of_injective (hg : injective g)
(y : non_zero_divisors A) : is_unit (g y) :=
is_unit.mk0 (g y) $ map_ne_zero_of_mem_non_zero_divisors hg
/-- Given an integral domain `A`, a localization map to its fields of fractions
`f : A →+* K`, and an injective ring hom `g : A →+* L` where `L` is a field, we get a
field hom sending `z : K` to `g x * (g y)⁻¹`, where `(x, y) : A × (non_zero_divisors A)` are
such that `z = f x * (f y)⁻¹`. -/
noncomputable def lift (hg : injective g) : K →+* L :=
f.lift $ is_unit_map_of_injective hg
/-- Given an integral domain `A`, a localization map to its fields of fractions
`f : A →+* K`, and an injective ring hom `g : A →+* L` where `L` is a field,
field hom induced from `K` to `L` maps `f x / f y` to `g x / g y` for all
`x : A, y ∈ non_zero_divisors A`. -/
@[simp] lemma lift_mk' (hg : injective g) (x y) :
f.lift hg (f.mk' x y) = g x / g y :=
begin
erw f.lift_mk' (is_unit_map_of_injective hg),
erw submonoid.localization_map.mul_inv_left
(λ y : non_zero_divisors A, show is_unit (g.to_monoid_hom y), from
is_unit_map_of_injective hg y),
exact (mul_div_cancel' _ (map_ne_zero_of_mem_non_zero_divisors hg)).symm,
end
/-- Given integral domains `A, B` and localization maps to their fields of fractions
`f : A →+* K, g : B →+* L` and an injective ring hom `j : A →+* B`, we get a field hom
sending `z : K` to `g (j x) * (g (j y))⁻¹`, where `(x, y) : A × (non_zero_divisors A)` are
such that `z = f x * (f y)⁻¹`. -/
noncomputable def map (g : fraction_map B L) {j : A →+* B} (hj : injective j) :
K →+* L :=
f.map (λ y, mem_non_zero_divisors_iff_ne_zero.2 $
map_ne_zero_of_mem_non_zero_divisors hj) g
/-- Given integral domains `A, B` and localization maps to their fields of fractions
`f : A →+* K, g : B →+* L`, an isomorphism `j : A ≃+* B` induces an isomorphism of
fields of fractions `K ≃+* L`. -/
noncomputable def field_equiv_of_ring_equiv (g : fraction_map B L) (h : A ≃+* B) :
K ≃+* L :=
f.ring_equiv_of_ring_equiv g h
begin
ext b,
show b ∈ h.to_equiv '' _ ↔ _,
erw [h.to_equiv.image_eq_preimage, set.preimage, set.mem_set_of_eq,
mem_non_zero_divisors_iff_ne_zero, mem_non_zero_divisors_iff_ne_zero],
exact h.symm.map_ne_zero_iff
end
/-- The cast from `int` to `rat` as a `fraction_map`. -/
def int.fraction_map : fraction_map ℤ ℚ :=
{ to_fun := coe,
map_units' :=
begin
rintro ⟨x, hx⟩,
rw [submonoid.mem_carrier, mem_non_zero_divisors_iff_ne_zero] at hx,
simpa only [is_unit_iff_ne_zero, int.cast_eq_zero, ne.def, subtype.coe_mk] using hx,
end,
surj' :=
begin
rintro ⟨n, d, hd, h⟩,
refine ⟨⟨n, ⟨d, _⟩⟩, rat.mul_denom_eq_num⟩,
rwa [submonoid.mem_carrier, mem_non_zero_divisors_iff_ne_zero, int.coe_nat_ne_zero_iff_pos]
end,
eq_iff_exists' :=
begin
intros x y,
rw [int.cast_inj],
refine ⟨by { rintro rfl, use 1 }, _⟩,
rintro ⟨⟨c, hc⟩, h⟩,
apply int.eq_of_mul_eq_mul_right _ h,
rwa [submonoid.mem_carrier, mem_non_zero_divisors_iff_ne_zero] at hc,
end,
..int.cast_ring_hom ℚ }
end fraction_map
variables (A)
/-- The fraction field of an integral domain as a quotient type. -/
@[reducible] def fraction_ring := localization (non_zero_divisors A)
/-- Natural hom sending `x : A`, `A` an integral domain, to the equivalence class of
`(x, 1)` in the field of fractions of `A`. -/
def of : fraction_map A (localization (non_zero_divisors A)) :=
localization.of (non_zero_divisors A)
namespace fraction_ring
variables {A}
noncomputable instance : field (fraction_ring A) :=
(of A).to_field
@[simp] lemma mk_eq_div {r s} : (localization.mk r s : fraction_ring A) =
((of A).to_map r / (of A).to_map s : fraction_ring A) :=
by erw [localization.mk_eq_mk', (of A).mk'_eq_div]
/-- Given an integral domain `A` and a localization map to a field of fractions
`f : A →+* K`, we get an isomorphism between the field of fractions of `A` as a quotient
type and `K`. -/
noncomputable def field_equiv_of_quotient {K : Type*} [field K] (f : fraction_map A K) :
fraction_ring A ≃+* K :=
localization.ring_equiv_of_quotient f
end fraction_ring
|
18fb277b5513aa23680d7cb7eceed1b3446c3f83 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/topology/category/Compactum_auto.lean | 4078d12bbfe0c4fc2e71798c23a0e3c389387fb8 | [] | 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 | 10,478 | lean | /-
Copyright (c) 2020 Adam Topaz. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Adam Topaz
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.category_theory.monad.types
import Mathlib.category_theory.monad.limits
import Mathlib.category_theory.equivalence
import Mathlib.topology.category.CompHaus
import Mathlib.data.set.constructions
import Mathlib.PostPort
universes u_1 u_2
namespace Mathlib
/-!
# Compacta and Compact Hausdorff Spaces
Recall that, given a monad `M` on `Type*`, an *algebra* for `M` consists of the following data:
- A type `X : Type*`
- A "structure" map `M X → X`.
This data must also satisfy a distributivity and unit axiom, and algebras for `M` form a category
in an evident way.
See the file `category_theory.monad.algebra` for a general version, as well as the following link.
https://ncatlab.org/nlab/show/monad
This file proves the equivalence between the category of *compact Hausdorff topological spaces*
and the category of algebras for the *ultrafilter monad*.
## Notation:
Here are the main objects introduced in this file.
- `Compactum` is the type of compacta, which we define as algebras for the ultrafilter monad.
- `Compactum_to_CompHaus` is the functor `Compactum ⥤ CompHaus`. Here `CompHaus` is the usual
category of compact Hausdorff spaces.
- `Compactum_to_CompHaus.is_equivalence` is a term of type `is_equivalence Compactum_to_CompHaus`.
The proof of this equivalence is a bit technical. But the idea is quite simply that the structure
map `ultrafilter X → X` for an algebra `X` of the ultrafilter monad should be considered as the map
sending an ultrafilter to its limit in `X`. The topology on `X` is then defined by mimicking the
characterization of open sets in terms of ultrafilters.
Any `X : Compactum` is endowed with a coercion to `Type*`, as well as the following instances:
- `topological_space X`.
- `compact_space X`.
- `t2_space X`.
Any morphism `f : X ⟶ Y` of is endowed with a coercion to a function `X → Y`, which is shown to
be continuous in `continuous_of_hom`.
The function `Compactum.of_topological_space` can be used to construct a `Compactum` from a
topological space which satisfies `compact_space` and `t2_space`.
We also add wrappers around structures which already exist. Here are the main ones, all in the
`Compactum` namespace:
- `forget : Compactum ⥤ Type*` is the forgetful functor, which induces a `concrete_category`
instance for `Compactum`.
- `free : Type* ⥤ Compactum` is the left adjoint to `forget`, and the adjunction is in `adj`.
- `str : ultrafilter X → X` is the structure map for `X : Compactum`.
The notation `X.str` is preferred.
- `join : ultrafilter (ultrafilter X) → ultrafilter X` is the monadic join for `X : Compactum`.
Again, the notation `X.join` is preferred.
- `incl : X → ultrafilter X` is the unit for `X : Compactum`. The notation `X.incl` is preferred.
## References
- E. Manes, Algebraic Theories, Graduate Texts in Mathematics 26, Springer-Verlag, 1976.
- https://ncatlab.org/nlab/show/ultrafilter
-/
/-- The type `Compactum` of Compacta, defined as algebras for the ultrafilter monad. -/
def Compactum := category_theory.monad.algebra (category_theory.of_type_functor ultrafilter)
namespace Compactum
/-- The forgetful functor to Type* -/
def forget : Compactum ⥤ Type u_1 :=
category_theory.monad.forget (category_theory.of_type_functor ultrafilter)
/-- The "free" Compactum functor. -/
def free : Type u_1 ⥤ Compactum :=
category_theory.monad.free (category_theory.of_type_functor ultrafilter)
/-- The adjunction between `free` and `forget`. -/
def adj : free ⊣ forget := category_theory.monad.adj (category_theory.of_type_functor ultrafilter)
-- Basic instances
protected instance category_theory.concrete_category :
category_theory.concrete_category Compactum :=
category_theory.concrete_category.mk forget
protected instance has_coe_to_sort : has_coe_to_sort Compactum :=
has_coe_to_sort.mk (Type u_1) (category_theory.functor.obj forget)
protected instance category_theory.has_hom.hom.has_coe_to_fun {X : Compactum} {Y : Compactum} :
has_coe_to_fun (X ⟶ Y) :=
has_coe_to_fun.mk (fun (f : X ⟶ Y) => ↥X → ↥Y)
fun (f : X ⟶ Y) => category_theory.monad.algebra.hom.f f
protected instance category_theory.limits.has_limits :
category_theory.limits.has_limits Compactum :=
category_theory.has_limits_of_has_limits_creates_limits forget
/-- The structure map for a compactum, essentially sending an ultrafilter to its limit. -/
def str (X : Compactum) : ultrafilter ↥X → ↥X := category_theory.monad.algebra.a X
/-- The monadic join. -/
def join (X : Compactum) : ultrafilter (ultrafilter ↥X) → ultrafilter ↥X :=
category_theory.nat_trans.app μ_ ↥X
/-- The inclusion of `X` into `ultrafilter X`. -/
def incl (X : Compactum) : ↥X → ultrafilter ↥X :=
category_theory.nat_trans.app η_ (category_theory.functor.obj forget X)
@[simp] theorem str_incl (X : Compactum) (x : ↥X) : str X (incl X x) = x := sorry
@[simp] theorem str_hom_commute (X : Compactum) (Y : Compactum) (f : X ⟶ Y) (xs : ultrafilter ↥X) :
coe_fn f (str X xs) = str Y (ultrafilter.map (⇑f) xs) :=
sorry
@[simp] theorem join_distrib (X : Compactum) (uux : ultrafilter (ultrafilter ↥X)) :
str X (join X uux) = str X (ultrafilter.map (str X) uux) :=
sorry
protected instance topological_space {X : Compactum} : topological_space ↥X :=
topological_space.mk (fun (U : set ↥X) => ∀ (F : ultrafilter ↥X), str X F ∈ U → U ∈ F) sorry sorry
sorry
theorem is_closed_iff {X : Compactum} (S : set ↥X) :
is_closed S ↔ ∀ (F : ultrafilter ↥X), S ∈ F → str X F ∈ S :=
sorry
protected instance compact_space {X : Compactum} : compact_space ↥X :=
compact_space.mk
(eq.mpr
(id (Eq._oldrec (Eq.refl (is_compact set.univ)) (propext compact_iff_ultrafilter_le_nhds)))
fun (F : ultrafilter ↥X) (h : ↑F ≤ filter.principal set.univ) =>
Exists.intro (str X F)
(Exists.intro trivial
(eq.mpr (id (Eq._oldrec (Eq.refl (↑F ≤ nhds (str X F))) (propext le_nhds_iff)))
fun (S : set ↥X) (h1 : str X F ∈ S) (h2 : is_open S) => h2 F h1)))
/-- A local definition used only in the proofs. -/
/-- A local definition used only in the proofs. -/
theorem is_closed_cl {X : Compactum} (A : set ↥X) : is_closed (cl A) :=
eq.mpr (id (Eq._oldrec (Eq.refl (is_closed (cl A))) (propext (is_closed_iff (cl A)))))
fun (F : ultrafilter ↥X) (hF : cl A ∈ F) =>
cl_cl A (Exists.intro F { left := hF, right := rfl })
theorem str_eq_of_le_nhds {X : Compactum} (F : ultrafilter ↥X) (x : ↥X) :
↑F ≤ nhds x → str X F = x :=
sorry
theorem le_nhds_of_str_eq {X : Compactum} (F : ultrafilter ↥X) (x : ↥X) :
str X F = x → ↑F ≤ nhds x :=
fun (h : str X F = x) =>
iff.mpr le_nhds_iff
fun (s : set ↥X) (hx : x ∈ s) (hs : is_open s) =>
hs F (eq.mpr (id (Eq._oldrec (Eq.refl (str X F ∈ s)) h)) hx)
-- All the hard work above boils down to this t2_space instance.
protected instance t2_space {X : Compactum} : t2_space ↥X :=
eq.mpr (id (Eq._oldrec (Eq.refl (t2_space ↥X)) (propext t2_iff_ultrafilter)))
fun (x y : ↥X) (F : ultrafilter ↥X) (hx : ↑F ≤ nhds x) (hy : ↑F ≤ nhds y) =>
eq.mpr (id (Eq._oldrec (Eq.refl (x = y)) (Eq.symm (str_eq_of_le_nhds F x hx))))
(eq.mpr (id (Eq._oldrec (Eq.refl (str X F = y)) (Eq.symm (str_eq_of_le_nhds F y hy))))
(Eq.refl (str X F)))
/-- The structure map of a compactum actually computes limits. -/
theorem Lim_eq_str {X : Compactum} (F : ultrafilter ↥X) : ultrafilter.Lim F = str X F :=
eq.mpr
(id
(Eq._oldrec (Eq.refl (ultrafilter.Lim F = str X F)) (propext ultrafilter.Lim_eq_iff_le_nhds)))
(eq.mpr (id (Eq._oldrec (Eq.refl (↑F ≤ nhds (str X F))) (propext le_nhds_iff)))
fun (s : set ↥X) (ᾰ : str X F ∈ s) (ᾰ_1 : is_open s) => ᾰ_1 F ᾰ)
theorem cl_eq_closure {X : Compactum} (A : set ↥X) : cl A = closure A := sorry
/-- Any morphism of compacta is continuous. -/
theorem continuous_of_hom {X : Compactum} {Y : Compactum} (f : X ⟶ Y) : continuous ⇑f := sorry
/-- Given any compact Hausdorff space, we construct a Compactum. -/
def of_topological_space (X : Type u_1) [topological_space X] [compact_space X] [t2_space X] :
Compactum :=
category_theory.monad.algebra.mk X ultrafilter.Lim
/-- Any continuous map between Compacta is a morphism of compacta. -/
def hom_of_continuous {X : Compactum} {Y : Compactum} (f : ↥X → ↥Y) (cont : continuous f) : X ⟶ Y :=
category_theory.monad.algebra.hom.mk f
end Compactum
/-- The functor functor from Compactum to CompHaus. -/
def Compactum_to_CompHaus : Compactum ⥤ CompHaus :=
category_theory.functor.mk (fun (X : Compactum) => CompHaus.mk (category_theory.bundled.mk ↥X))
fun (X Y : Compactum) (f : X ⟶ Y) => continuous_map.mk ⇑f
namespace Compactum_to_CompHaus
/-- The functor Compactum_to_CompHaus is full. -/
def full : category_theory.full Compactum_to_CompHaus :=
category_theory.full.mk
fun (X Y : Compactum)
(f :
category_theory.functor.obj Compactum_to_CompHaus X ⟶
category_theory.functor.obj Compactum_to_CompHaus Y) =>
Compactum.hom_of_continuous (continuous_map.to_fun f) sorry
/-- The functor Compactum_to_CompHaus is faithful. -/
theorem faithful : category_theory.faithful Compactum_to_CompHaus := category_theory.faithful.mk
/-- This definition is used to prove essential surjectivity of Compactum_to_CompHaus. -/
def iso_of_topological_space {D : CompHaus} :
category_theory.functor.obj Compactum_to_CompHaus (Compactum.of_topological_space ↥D) ≅ D :=
category_theory.iso.mk (continuous_map.mk id) (continuous_map.mk id)
/-- The functor Compactum_to_CompHaus is essentially surjective. -/
theorem ess_surj : category_theory.ess_surj Compactum_to_CompHaus :=
category_theory.ess_surj.mk
fun (X : CompHaus) =>
Exists.intro (Compactum.of_topological_space ↥X) (Nonempty.intro iso_of_topological_space)
/-- The functor Compactum_to_CompHaus is an equivalence of categories. -/
def is_equivalence : category_theory.is_equivalence Compactum_to_CompHaus :=
category_theory.equivalence.equivalence_of_fully_faithfully_ess_surj Compactum_to_CompHaus
end Mathlib |
9d5ea0884490dc80f3bfdec6eacc1a9a936533c3 | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/data/real/sign.lean | 34f156eb1119a7e2053447c83d28b0bfd38acc00 | [
"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 | 3,850 | lean | /-
Copyright (c) 2021 Kexing Ying. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kexing Ying, Eric Wieser
-/
import data.real.basic
/-!
# Real sign function
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
This file introduces and contains some results about `real.sign` which maps negative
real numbers to -1, positive real numbers to 1, and 0 to 0.
## Main definitions
* `real.sign r` is $\begin{cases} -1 & \text{if } r < 0, \\
~~\, 0 & \text{if } r = 0, \\
~~\, 1 & \text{if } r > 0. \end{cases}$
## Tags
sign function
-/
namespace real
/-- The sign function that maps negative real numbers to -1, positive numbers to 1, and 0
otherwise. -/
noncomputable
def sign (r : ℝ) : ℝ :=
if r < 0 then -1 else
if 0 < r then 1 else
0
lemma sign_of_neg {r : ℝ} (hr : r < 0) : sign r = -1 :=
by rw [sign, if_pos hr]
lemma sign_of_pos {r : ℝ} (hr : 0 < r) : sign r = 1 :=
by rw [sign, if_pos hr, if_neg hr.not_lt]
@[simp]
lemma sign_zero : sign 0 = 0 :=
by rw [sign, if_neg (lt_irrefl _), if_neg (lt_irrefl _)]
@[simp]
lemma sign_one : sign 1 = 1 :=
sign_of_pos $ by norm_num
lemma sign_apply_eq (r : ℝ) : sign r = -1 ∨ sign r = 0 ∨ sign r = 1 :=
begin
obtain hn | rfl | hp := lt_trichotomy r (0 : ℝ),
{ exact (or.inl $ sign_of_neg hn) },
{ exact (or.inr $ or.inl $ sign_zero) },
{ exact (or.inr $ or.inr $ sign_of_pos hp) },
end
/-- This lemma is useful for working with `ℝˣ` -/
lemma sign_apply_eq_of_ne_zero (r : ℝ) (h : r ≠ 0) : sign r = -1 ∨ sign r = 1 :=
begin
obtain hn | rfl | hp := lt_trichotomy r (0 : ℝ),
{ exact (or.inl $ sign_of_neg hn) },
{ exact (h rfl).elim },
{ exact (or.inr $ sign_of_pos hp) },
end
@[simp]
lemma sign_eq_zero_iff {r : ℝ} : sign r = 0 ↔ r = 0 :=
begin
refine ⟨λ h, _, λ h, h.symm ▸ sign_zero⟩,
obtain hn | rfl | hp := lt_trichotomy r (0 : ℝ),
{ rw [sign_of_neg hn, neg_eq_zero] at h, exact (one_ne_zero h).elim },
{ refl },
{ rw sign_of_pos hp at h, exact (one_ne_zero h).elim },
end
lemma sign_int_cast (z : ℤ) : sign (z : ℝ) = ↑(int.sign z) :=
begin
obtain hn | rfl | hp := lt_trichotomy z (0 : ℤ),
{ rw [sign_of_neg (int.cast_lt_zero.mpr hn), int.sign_eq_neg_one_of_neg hn, int.cast_neg,
int.cast_one], },
{ rw [int.cast_zero, sign_zero, int.sign_zero, int.cast_zero], },
{ rw [sign_of_pos (int.cast_pos.mpr hp), int.sign_eq_one_of_pos hp, int.cast_one] }
end
lemma sign_neg {r : ℝ} : sign (-r) = - sign r :=
begin
obtain hn | rfl | hp := lt_trichotomy r (0 : ℝ),
{ rw [sign_of_neg hn, sign_of_pos (neg_pos.mpr hn), neg_neg] },
{ rw [sign_zero, neg_zero, sign_zero] },
{ rw [sign_of_pos hp, sign_of_neg (neg_lt_zero.mpr hp)] },
end
lemma sign_mul_nonneg (r : ℝ) : 0 ≤ sign r * r :=
begin
obtain hn | rfl | hp := lt_trichotomy r (0 : ℝ),
{ rw sign_of_neg hn,
exact mul_nonneg_of_nonpos_of_nonpos (by norm_num) hn.le },
{ rw mul_zero, },
{ rw [sign_of_pos hp, one_mul],
exact hp.le }
end
lemma sign_mul_pos_of_ne_zero (r : ℝ) (hr : r ≠ 0) : 0 < sign r * r :=
begin
refine lt_of_le_of_ne (sign_mul_nonneg r) (λ h, hr _),
have hs0 := (zero_eq_mul.mp h).resolve_right hr,
exact sign_eq_zero_iff.mp hs0,
end
@[simp]
lemma inv_sign (r : ℝ) : (sign r)⁻¹ = sign r :=
begin
obtain (hn | hz | hp) := sign_apply_eq r,
{ rw hn, norm_num },
{ rw hz, exact inv_zero },
{ rw hp, exact inv_one }
end
@[simp]
lemma sign_inv (r : ℝ) : sign r⁻¹ = sign r :=
begin
obtain hn | rfl | hp := lt_trichotomy r (0 : ℝ),
{ rw [sign_of_neg hn, sign_of_neg (inv_lt_zero.mpr hn)] },
{ rw [sign_zero, inv_zero, sign_zero] },
{ rw [sign_of_pos hp, sign_of_pos (inv_pos.mpr hp)] },
end
end real
|
b7743317cddd7362d921e7d3bd0fff2cfe0664bb | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/topology/category/Top/limits_auto.lean | ac92a8138d37265df666d89704841954e7754332 | [] | 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 | 6,080 | lean | /-
Copyright (c) 2017 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Patrick Massot, Scott Morrison, Mario Carneiro
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.topology.category.Top.basic
import Mathlib.category_theory.limits.types
import Mathlib.category_theory.limits.preserves.basic
import Mathlib.PostPort
universes u
namespace Mathlib
namespace Top
/--
A choice of limit cone for a functor `F : J ⥤ Top`.
Generally you should just use `limit.cone F`, unless you need the actual definition
(which is in terms of `types.limit_cone`).
-/
def limit_cone {J : Type u} [category_theory.small_category J] (F : J ⥤ Top) :
category_theory.limits.cone F :=
category_theory.limits.cone.mk
(category_theory.bundled.mk
(category_theory.limits.cone.X
(category_theory.limits.types.limit_cone (F ⋙ category_theory.forget Top))))
(category_theory.nat_trans.mk
fun (j : J) =>
continuous_map.mk
(category_theory.nat_trans.app
(category_theory.limits.cone.π
(category_theory.limits.types.limit_cone (F ⋙ category_theory.forget Top)))
j))
/--
The chosen cone `Top.limit_cone F` for a functor `F : J ⥤ Top` is a limit cone.
Generally you should just use `limit.is_limit F`, unless you need the actual definition
(which is in terms of `types.limit_cone_is_limit`).
-/
def limit_cone_is_limit {J : Type u} [category_theory.small_category J] (F : J ⥤ Top) :
category_theory.limits.is_limit (limit_cone F) :=
category_theory.limits.is_limit.of_faithful (category_theory.forget Top)
(category_theory.limits.types.limit_cone_is_limit (F ⋙ category_theory.forget Top))
(fun (s : category_theory.limits.cone F) =>
continuous_map.mk
fun
(v :
category_theory.limits.cone.X
(category_theory.functor.map_cone (category_theory.forget Top) s)) =>
{ val :=
fun (j : J) =>
category_theory.nat_trans.app
(category_theory.limits.cone.π
(category_theory.functor.map_cone (category_theory.forget Top) s))
j v,
property := sorry })
sorry
protected instance Top_has_limits : category_theory.limits.has_limits Top :=
category_theory.limits.has_limits.mk
fun (J : Type u) (𝒥 : category_theory.small_category J) =>
category_theory.limits.has_limits_of_shape.mk
fun (F : J ⥤ Top) =>
category_theory.limits.has_limit.mk
(category_theory.limits.limit_cone.mk (limit_cone F) (limit_cone_is_limit F))
protected instance forget_preserves_limits :
category_theory.limits.preserves_limits (category_theory.forget Top) :=
category_theory.limits.preserves_limits.mk
fun (J : Type u) (𝒥 : category_theory.small_category J) =>
category_theory.limits.preserves_limits_of_shape.mk
fun (F : J ⥤ Top) =>
category_theory.limits.preserves_limit_of_preserves_limit_cone (limit_cone_is_limit F)
(category_theory.limits.types.limit_cone_is_limit (F ⋙ category_theory.forget Top))
/--
A choice of colimit cocone for a functor `F : J ⥤ Top`.
Generally you should just use `colimit.coone F`, unless you need the actual definition
(which is in terms of `types.colimit_cocone`).
-/
def colimit_cocone {J : Type u} [category_theory.small_category J] (F : J ⥤ Top) :
category_theory.limits.cocone F :=
category_theory.limits.cocone.mk
(category_theory.bundled.mk
(category_theory.limits.cocone.X
(category_theory.limits.types.colimit_cocone (F ⋙ category_theory.forget Top))))
(category_theory.nat_trans.mk
fun (j : J) =>
continuous_map.mk
(category_theory.nat_trans.app
(category_theory.limits.cocone.ι
(category_theory.limits.types.colimit_cocone (F ⋙ category_theory.forget Top)))
j))
/--
The chosen cocone `Top.colimit_cocone F` for a functor `F : J ⥤ Top` is a colimit cocone.
Generally you should just use `colimit.is_colimit F`, unless you need the actual definition
(which is in terms of `types.colimit_cocone_is_colimit`).
-/
def colimit_cocone_is_colimit {J : Type u} [category_theory.small_category J] (F : J ⥤ Top) :
category_theory.limits.is_colimit (colimit_cocone F) :=
category_theory.limits.is_colimit.of_faithful (category_theory.forget Top)
(category_theory.limits.types.colimit_cocone_is_colimit (F ⋙ category_theory.forget Top))
(fun (s : category_theory.limits.cocone F) =>
continuous_map.mk
(Quot.lift
(fun
(p :
sigma fun (j : J) => category_theory.functor.obj (F ⋙ category_theory.forget Top) j) =>
category_theory.nat_trans.app
(category_theory.limits.cocone.ι
(category_theory.functor.map_cocone (category_theory.forget Top) s))
(sigma.fst p) (sigma.snd p))
sorry))
sorry
protected instance Top_has_colimits : category_theory.limits.has_colimits Top :=
category_theory.limits.has_colimits.mk
fun (J : Type u) (𝒥 : category_theory.small_category J) =>
category_theory.limits.has_colimits_of_shape.mk
fun (F : J ⥤ Top) =>
category_theory.limits.has_colimit.mk
(category_theory.limits.colimit_cocone.mk (colimit_cocone F)
(colimit_cocone_is_colimit F))
protected instance forget_preserves_colimits :
category_theory.limits.preserves_colimits (category_theory.forget Top) :=
category_theory.limits.preserves_colimits.mk
fun (J : Type u) (𝒥 : category_theory.small_category J) =>
category_theory.limits.preserves_colimits_of_shape.mk
fun (F : J ⥤ Top) =>
category_theory.limits.preserves_colimit_of_preserves_colimit_cocone
(colimit_cocone_is_colimit F)
(category_theory.limits.types.colimit_cocone_is_colimit
(F ⋙ category_theory.forget Top))
end Mathlib |
47faae5a158d4df074951fb9d5fd6dfddb90c6cc | bbecf0f1968d1fba4124103e4f6b55251d08e9c4 | /src/number_theory/dioph.lean | bbed466e2190d06d47ab1abd905d5b88615b5a77 | [
"Apache-2.0"
] | permissive | waynemunro/mathlib | e3fd4ff49f4cb43d4a8ded59d17be407bc5ee552 | 065a70810b5480d584033f7bbf8e0409480c2118 | refs/heads/master | 1,693,417,182,397 | 1,634,644,781,000 | 1,634,644,781,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 27,947 | 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.fin.fin2
import data.pfun
import data.vector3
import number_theory.pell
/-!
# Diophantine functions and Matiyasevic's theorem
Hilbert's tenth problem asked whether there exists an algorithm which for a given integer polynomial
determines whether this polynomial has integer solutions. It was answered in the negative in 1970,
the final step being completed by Matiyasevic who showed that the power function is Diophantine.
Here a function is called Diophantine if its graph is Diophantine as a set. A subset `S ⊆ ℕ ^ α` in
turn is called Diophantine if there exists an integer polynomial on `α ⊕ β` such that `v ∈ S` iff
there exists `t : ℕ^β` with `p (v, t) = 0`.
## Main definitions
* `is_poly`: a predicate stating that a function is a multivariate integer polynomial.
* `poly`: the type of multivariate integer polynomial functions.
* `dioph`: a predicate stating that a set `S ⊆ ℕ^α` is Diophantine, i.e. that
* `dioph_fn`: a predicate on a function stating that it is Diophantine in the sense that its graph
is Diophantine as a set.
## Main statements
* `pell_dioph` states that solutions to Pell's equation form a Diophantine set.
* `pow_dioph` states that the power function is Diophantine, a version of Matiyasevic's theorem.
## References
* [M. Carneiro, _A Lean formalization of Matiyasevic's theorem_][carneiro2018matiyasevic]
* [M. Davis, _Hilbert's tenth problem is unsolvable_][MR317916]
## Tags
Matiyasevic's theorem, Hilbert's tenth problem
## TODO
* Finish the solution of Hilbert's tenth problem.
* Connect `poly` to `mv_polynomial`
-/
universe u
open nat function
namespace int
lemma eq_nat_abs_iff_mul (x n) : nat_abs x = n ↔ (x - n) * (x + n) = 0 :=
begin
refine iff.trans _ mul_eq_zero.symm,
refine iff.trans _ (or_congr sub_eq_zero add_eq_zero_iff_eq_neg).symm,
exact ⟨λe, by rw ← e; apply nat_abs_eq,
λo, by cases o; subst x; simp [nat_abs_of_nat]⟩
end
end int
open fin2
/-- `list_all p l` is equivalent to `∀ a ∈ l, p a`, but unfolds directly to a conjunction,
i.e. `list_all p [0, 1, 2] = p 0 ∧ p 1 ∧ p 2`. -/
@[simp] def list_all {α} (p : α → Prop) : list α → Prop
| [] := true
| (x :: []) := p x
| (x :: l) := p x ∧ list_all l
@[simp] theorem list_all_cons {α} (p : α → Prop) (x : α) :
∀ (l : list α), list_all p (x :: l) ↔ p x ∧ list_all p l
| [] := (and_true _).symm
| (x :: l) := iff.rfl
theorem list_all_iff_forall {α} (p : α → Prop) : ∀ (l : list α), list_all p l ↔ ∀ x ∈ l, p x
| [] := (iff_true_intro $ list.ball_nil _).symm
| (x :: l) := by rw [list.ball_cons, ← list_all_iff_forall l]; simp
theorem list_all.imp {α} {p q : α → Prop} (h : ∀ x, p x → q x) :
∀ {l : list α}, list_all p l → list_all q l
| [] := id
| (x :: l) := by simpa using and.imp (h x) list_all.imp
@[simp] theorem list_all_map {α β} {p : β → Prop} (f : α → β) {l : list α} :
list_all p (l.map f) ↔ list_all (p ∘ f) l :=
by induction l; simp *
theorem list_all_congr {α} {p q : α → Prop} (h : ∀ x, p x ↔ q x) {l : list α} :
list_all p l ↔ list_all q l :=
⟨list_all.imp (λx, (h x).1), list_all.imp (λx, (h x).2)⟩
instance decidable_list_all {α} (p : α → Prop) [decidable_pred p] (l : list α) :
decidable (list_all p l) :=
decidable_of_decidable_of_iff (by apply_instance) (list_all_iff_forall _ _).symm
/- poly -/
/-- A predicate asserting that a function is a multivariate integer polynomial.
(We are being a bit lazy here by allowing many representations for multiplication,
rather than only allowing monomials and addition, but the definition is equivalent
and this is easier to use.) -/
inductive is_poly {α} : ((α → ℕ) → ℤ) → Prop
| proj : ∀ i, is_poly (λx : α → ℕ, x i)
| const : Π (n : ℤ), is_poly (λx : α → ℕ, n)
| sub : Π {f g : (α → ℕ) → ℤ}, is_poly f → is_poly g → is_poly (λx, f x - g x)
| mul : Π {f g : (α → ℕ) → ℤ}, is_poly f → is_poly g → is_poly (λx, f x * g x)
/-- The type of multivariate integer polynomials -/
def poly (α : Type u) := {f : (α → ℕ) → ℤ // is_poly f}
namespace poly
section
parameter {α : Type u}
instance : has_coe_to_fun (poly α) := ⟨_, λ f, f.1⟩
/-- The underlying function of a `poly` is a polynomial -/
lemma isp (f : poly α) : is_poly f := f.2
/-- Extensionality for `poly α` -/
lemma ext {f g : poly α} (e : ∀x, f x = g x) : f = g :=
subtype.eq (funext e)
/-- Construct a `poly` given an extensionally equivalent `poly`. -/
def subst (f : poly α) (g : (α → ℕ) → ℤ) (e : ∀x, f x = g x) : poly α :=
⟨g, by rw ← (funext e : coe_fn f = g); exact f.isp⟩
@[simp] theorem subst_eval (f g e x) : subst f g e x = g x := rfl
/-- The `i`th projection function, `x_i`. -/
def proj (i) : poly α := ⟨_, is_poly.proj i⟩
@[simp] theorem proj_eval (i x) : proj i x = x i := rfl
/-- The constant function with value `n : ℤ`. -/
def const (n) : poly α := ⟨_, is_poly.const n⟩
@[simp] theorem const_eval (n x) : const n x = n := rfl
/-- The zero polynomial -/
def zero : poly α := const 0
instance : has_zero (poly α) := ⟨poly.zero⟩
@[simp] theorem zero_eval (x) : (0 : poly α) x = 0 := rfl
/-- The zero polynomial -/
def one : poly α := const 1
instance : has_one (poly α) := ⟨poly.one⟩
@[simp] theorem one_eval (x) : (1 : poly α) x = 1 := rfl
/-- Subtraction of polynomials -/
def sub : poly α → poly α → poly α | ⟨f, pf⟩ ⟨g, pg⟩ :=
⟨_, is_poly.sub pf pg⟩
instance : has_sub (poly α) := ⟨poly.sub⟩
@[simp] theorem sub_eval : Π (f g x), (f - g : poly α) x = f x - g x
| ⟨f, pf⟩ ⟨g, pg⟩ x := rfl
/-- Negation of a polynomial -/
def neg (f : poly α) : poly α := 0 - f
instance : has_neg (poly α) := ⟨poly.neg⟩
@[simp] theorem neg_eval (f x) : (-f : poly α) x = -f x :=
show (0-f) x = _, by simp
/-- Addition of polynomials -/
def add : poly α → poly α → poly α | ⟨f, pf⟩ ⟨g, pg⟩ :=
subst (⟨f, pf⟩ - -⟨g, pg⟩) _
(λx, show f x - (0 - g x) = f x + g x, by simp)
instance : has_add (poly α) := ⟨poly.add⟩
@[simp] theorem add_eval : Π (f g x), (f + g : poly α) x = f x + g x
| ⟨f, pf⟩ ⟨g, pg⟩ x := rfl
/-- Multiplication of polynomials -/
def mul : poly α → poly α → poly α | ⟨f, pf⟩ ⟨g, pg⟩ :=
⟨_, is_poly.mul pf pg⟩
instance : has_mul (poly α) := ⟨poly.mul⟩
@[simp] theorem mul_eval : Π (f g x), (f * g : poly α) x = f x * g x
| ⟨f, pf⟩ ⟨g, pg⟩ x := rfl
instance : comm_ring (poly α) := by refine_struct
{ add := (+),
zero := (0 : poly α),
neg := has_neg.neg,
mul := (*),
one := 1,
sub := has_sub.sub,
npow := @npow_rec _ ⟨1⟩ ⟨(*)⟩,
nsmul := @nsmul_rec _ ⟨0⟩ ⟨(+)⟩,
gsmul := @gsmul_rec _ ⟨0⟩ ⟨(+)⟩ ⟨neg⟩ };
intros; try { refl }; refine ext (λ _, _);
simp [sub_eq_add_neg, mul_add, mul_left_comm, mul_comm, add_comm, add_assoc]
lemma induction {C : poly α → Prop}
(H1 : ∀i, C (proj i)) (H2 : ∀n, C (const n))
(H3 : ∀f g, C f → C g → C (f - g))
(H4 : ∀f g, C f → C g → C (f * g)) (f : poly α) : C f :=
begin
cases f with f pf,
induction pf with i n f g pf pg ihf ihg f g pf pg ihf ihg,
apply H1, apply H2, apply H3 _ _ ihf ihg, apply H4 _ _ ihf ihg
end
/-- The sum of squares of a list of polynomials. This is relevant for
Diophantine equations, because it means that a list of equations
can be encoded as a single equation: `x = 0 ∧ y = 0 ∧ z = 0` is
equivalent to `x^2 + y^2 + z^2 = 0`. -/
def sumsq : list (poly α) → poly α
| [] := 0
| (p::ps) := p*p + sumsq ps
theorem sumsq_nonneg (x) : ∀ l, 0 ≤ sumsq l x
| [] := le_refl 0
| (p::ps) := by rw sumsq; simp [-add_comm];
exact add_nonneg (mul_self_nonneg _) (sumsq_nonneg ps)
theorem sumsq_eq_zero (x) : ∀ l, sumsq l x = 0 ↔ list_all (λa : poly α, a x = 0) l
| [] := eq_self_iff_true _
| (p::ps) := by rw [list_all_cons, ← sumsq_eq_zero ps]; rw sumsq; simp [-add_comm]; exact
⟨λ(h : p x * p x + sumsq ps x = 0),
have p x = 0, from eq_zero_of_mul_self_eq_zero $ le_antisymm
(by rw ← h; have t := add_le_add_left (sumsq_nonneg x ps) (p x * p x); rwa [add_zero] at t)
(mul_self_nonneg _),
⟨this, by simp [this] at h; exact h⟩,
λ⟨h1, h2⟩, by rw [h1, h2]; refl⟩
end
/-- Map the index set of variables, replacing `x_i` with `x_(f i)`. -/
def remap {α β} (f : α → β) (g : poly α) : poly β :=
⟨λv, g $ v ∘ f, g.induction
(λi, by simp; apply is_poly.proj)
(λn, by simp; apply is_poly.const)
(λf g pf pg, by simp; apply is_poly.sub pf pg)
(λf g pf pg, by simp; apply is_poly.mul pf pg)⟩
@[simp] theorem remap_eval {α β} (f : α → β) (g : poly α) (v) : remap f g v = g (v ∘ f) := rfl
end poly
namespace sum
/-- combine two functions into a function on the disjoint union -/
def join {α β γ} (f : α → γ) (g : β → γ) : α ⊕ β → γ :=
by {refine sum.rec _ _, exacts [f, g]}
end sum
local infixr ` ⊗ `:65 := sum.join
open sum
namespace option
/-- Functions from `option` can be combined similarly to `vector.cons` -/
def cons {α β} (a : β) (v : α → β) : option α → β :=
by {refine option.rec _ _, exacts [a, v]}
notation a :: b := cons a b
@[simp] theorem cons_head_tail {α β} (v : option α → β) : v none :: v ∘ some = v :=
funext $ λo, by cases o; refl
end option
/- dioph -/
/-- A set `S ⊆ ℕ^α` is Diophantine if there exists a polynomial on
`α ⊕ β` such that `v ∈ S` iff there exists `t : ℕ^β` with `p (v, t) = 0`. -/
def dioph {α : Type u} (S : set (α → ℕ)) : Prop :=
∃ {β : Type u} (p : poly (α ⊕ β)), ∀ (v : α → ℕ), S v ↔ ∃t, p (v ⊗ t) = 0
namespace dioph
section
variables {α β γ : Type u}
theorem ext {S S' : set (α → ℕ)} (d : dioph S) (H : ∀v, S v ↔ S' v) : dioph S' :=
eq.rec d $ show S = S', from set.ext H
theorem of_no_dummies (S : set (α → ℕ)) (p : poly α) (h : ∀ (v : α → ℕ), S v ↔ p v = 0) :
dioph S :=
⟨ulift empty, p.remap inl, λv, (h v).trans
⟨λh, ⟨λt, empty.rec _ t.down, by simp; rw [
show (v ⊗ λt:ulift empty, empty.rec _ t.down) ∘ inl = v, from rfl, h]⟩,
λ⟨t, ht⟩, by simp at ht; rwa [show (v ⊗ t) ∘ inl = v, from rfl] at ht⟩⟩
lemma inject_dummies_lem (f : β → γ) (g : γ → option β) (inv : ∀ x, g (f x) = some x)
(p : poly (α ⊕ β)) (v : α → ℕ) : (∃t, p (v ⊗ t) = 0) ↔
(∃t, p.remap (inl ⊗ (inr ∘ f)) (v ⊗ t) = 0) :=
begin
simp, refine ⟨λt, _, λt, _⟩; cases t with t ht,
{ have : (v ⊗ (0 :: t) ∘ g) ∘ (inl ⊗ inr ∘ f) = v ⊗ t :=
funext (λs, by cases s with a b; dsimp [join, (∘)]; try {rw inv}; refl),
exact ⟨(0 :: t) ∘ g, by rwa this⟩ },
{ have : v ⊗ t ∘ f = (v ⊗ t) ∘ (inl ⊗ inr ∘ f) :=
funext (λs, by cases s with a b; refl),
exact ⟨t ∘ f, by rwa this⟩ }
end
theorem inject_dummies {S : set (α → ℕ)} (f : β → γ) (g : γ → option β)
(inv : ∀ x, g (f x) = some x) (p : poly (α ⊕ β)) (h : ∀ (v : α → ℕ), S v ↔ ∃t, p (v ⊗ t) = 0) :
∃ q : poly (α ⊕ γ), ∀ (v : α → ℕ), S v ↔ ∃t, q (v ⊗ t) = 0 :=
⟨p.remap (inl ⊗ (inr ∘ f)), λv, (h v).trans $ inject_dummies_lem f g inv _ _⟩
theorem reindex_dioph {S : set (α → ℕ)} : Π (d : dioph S) (f : α → β), dioph (λv, S (v ∘ f))
| ⟨γ, p, pe⟩ f := ⟨γ, p.remap ((inl ∘ f) ⊗ inr), λv, (pe _).trans $ exists_congr $ λt,
suffices v ∘ f ⊗ t = (v ⊗ t) ∘ (inl ∘ f ⊗ inr), by simp [this],
funext $ λs, by cases s with a b; refl⟩
theorem dioph_list_all (l) (d : list_all dioph l) :
dioph (λv, list_all (λS : set (α → ℕ), S v) l) :=
suffices ∃ β (pl : list (poly (α ⊕ β))), ∀ v,
list_all (λS : set _, S v) l ↔ ∃t, list_all (λp : poly (α ⊕ β), p (v ⊗ t) = 0) pl,
from let ⟨β, pl, h⟩ := this
in ⟨β, poly.sumsq pl, λv, (h v).trans $ exists_congr $ λt, (poly.sumsq_eq_zero _ _).symm⟩,
begin
induction l with S l IH,
exact ⟨ulift empty, [], λv, by simp; exact ⟨λ⟨t⟩, empty.rec _ t, trivial⟩⟩,
simp at d,
exact let ⟨⟨β, p, pe⟩, dl⟩ := d, ⟨γ, pl, ple⟩ := IH dl in
⟨β ⊕ γ, p.remap (inl ⊗ inr ∘ inl) :: pl.map (λq, q.remap (inl ⊗ (inr ∘ inr))), λv,
by simp; exact iff.trans (and_congr (pe v) (ple v))
⟨λ⟨⟨m, hm⟩, ⟨n, hn⟩⟩,
⟨m ⊗ n, by rw [
show (v ⊗ m ⊗ n) ∘ (inl ⊗ inr ∘ inl) = v ⊗ m,
from funext $ λs, by cases s with a b; refl]; exact hm,
by { refine list_all.imp (λq hq, _) hn, dsimp [(∘)],
rw [show (λ (x : α ⊕ γ), (v ⊗ m ⊗ n) ((inl ⊗ λ (x : γ), inr (inr x)) x)) = v ⊗ n,
from funext $ λs, by cases s with a b; refl]; exact hq }⟩,
λ⟨t, hl, hr⟩,
⟨⟨t ∘ inl, by rwa [
show (v ⊗ t) ∘ (inl ⊗ inr ∘ inl) = v ⊗ t ∘ inl,
from funext $ λs, by cases s with a b; refl] at hl⟩,
⟨t ∘ inr, by {
refine list_all.imp (λq hq, _) hr, dsimp [(∘)] at hq,
rwa [show (λ (x : α ⊕ γ), (v ⊗ t) ((inl ⊗ λ (x : γ), inr (inr x)) x)) = v ⊗ t ∘ inr,
from funext $ λs, by cases s with a b; refl] at hq }⟩⟩⟩⟩
end
theorem and_dioph {S S' : set (α → ℕ)} (d : dioph S) (d' : dioph S') : dioph (λv, S v ∧ S' v) :=
dioph_list_all [S, S'] ⟨d, d'⟩
theorem or_dioph {S S' : set (α → ℕ)} : ∀ (d : dioph S) (d' : dioph S'), dioph (λv, S v ∨ S' v)
| ⟨β, p, pe⟩ ⟨γ, q, qe⟩ := ⟨β ⊕ γ, p.remap (inl ⊗ inr ∘ inl) * q.remap (inl ⊗ inr ∘ inr), λv,
begin
refine iff.trans (or_congr ((pe v).trans _) ((qe v).trans _))
(exists_or_distrib.symm.trans (exists_congr $ λt,
(@mul_eq_zero _ _ _ (p ((v ⊗ t) ∘ (inl ⊗ inr ∘ inl)))
(q ((v ⊗ t) ∘ (inl ⊗ inr ∘ inr)))).symm)),
exact inject_dummies_lem _ (some ⊗ (λ_, none)) (λx, rfl) _ _,
exact inject_dummies_lem _ ((λ_, none) ⊗ some) (λx, rfl) _ _,
end⟩
/-- A partial function is Diophantine if its graph is Diophantine. -/
def dioph_pfun (f : (α → ℕ) →. ℕ) := dioph (λv : option α → ℕ, f.graph (v ∘ some, v none))
/-- A function is Diophantine if its graph is Diophantine. -/
def dioph_fn (f : (α → ℕ) → ℕ) := dioph (λv : option α → ℕ, f (v ∘ some) = v none)
theorem reindex_dioph_fn {f : (α → ℕ) → ℕ} (d : dioph_fn f) (g : α → β) :
dioph_fn (λv, f (v ∘ g)) :=
reindex_dioph d (functor.map g)
theorem ex_dioph {S : set (α ⊕ β → ℕ)} : dioph S → dioph (λv, ∃x, S (v ⊗ x))
| ⟨γ, p, pe⟩ := ⟨β ⊕ γ, p.remap ((inl ⊗ inr ∘ inl) ⊗ inr ∘ inr), λv,
⟨λ⟨x, hx⟩, let ⟨t, ht⟩ := (pe _).1 hx in ⟨x ⊗ t, by simp; rw [
show (v ⊗ x ⊗ t) ∘ ((inl ⊗ inr ∘ inl) ⊗ inr ∘ inr) = (v ⊗ x) ⊗ t,
from funext $ λs, by cases s with a b; try {cases a}; refl]; exact ht⟩,
λ⟨t, ht⟩, ⟨t ∘ inl, (pe _).2 ⟨t ∘ inr, by simp at ht; rwa [
show (v ⊗ t) ∘ ((inl ⊗ inr ∘ inl) ⊗ inr ∘ inr) = (v ⊗ t ∘ inl) ⊗ t ∘ inr,
from funext $ λs, by cases s with a b; try {cases a}; refl] at ht⟩⟩⟩⟩
theorem ex1_dioph {S : set (option α → ℕ)} : dioph S → dioph (λv, ∃x, S (x :: v))
| ⟨β, p, pe⟩ := ⟨option β, p.remap (inr none :: inl ⊗ inr ∘ some), λv,
⟨λ⟨x, hx⟩, let ⟨t, ht⟩ := (pe _).1 hx in ⟨x :: t, by simp; rw [
show (v ⊗ x :: t) ∘ (inr none :: inl ⊗ inr ∘ some) = x :: v ⊗ t,
from funext $ λs, by cases s with a b; try {cases a}; refl]; exact ht⟩,
λ⟨t, ht⟩, ⟨t none, (pe _).2 ⟨t ∘ some, by simp at ht; rwa [
show (v ⊗ t) ∘ (inr none :: inl ⊗ inr ∘ some) = t none :: v ⊗ t ∘ some,
from funext $ λs, by cases s with a b; try {cases a}; refl] at ht⟩⟩⟩⟩
theorem dom_dioph {f : (α → ℕ) →. ℕ} (d : dioph_pfun f) : dioph f.dom :=
cast (congr_arg dioph $ set.ext $ λv, (pfun.dom_iff_graph _ _).symm) (ex1_dioph d)
theorem dioph_fn_iff_pfun (f : (α → ℕ) → ℕ) : dioph_fn f = @dioph_pfun α f :=
by refine congr_arg dioph (set.ext $ λv, _); exact pfun.lift_graph.symm
theorem abs_poly_dioph (p : poly α) : dioph_fn (λv, (p v).nat_abs) :=
by refine of_no_dummies _ ((p.remap some - poly.proj none) * (p.remap some + poly.proj none))
(λv, _); apply int.eq_nat_abs_iff_mul
theorem proj_dioph (i : α) : dioph_fn (λv, v i) :=
abs_poly_dioph (poly.proj i)
theorem dioph_pfun_comp1 {S : set (option α → ℕ)} (d : dioph S) {f} (df : dioph_pfun f) :
dioph (λv : α → ℕ, ∃ h : f.dom v, S (f.fn v h :: v)) :=
ext (ex1_dioph (and_dioph d df)) $ λv,
⟨λ⟨x, hS, (h: Exists _)⟩, by
rw [show (x :: v) ∘ some = v, from funext $ λs, rfl] at h;
cases h with hf h; refine ⟨hf, _⟩; rw [pfun.fn, h]; exact hS,
λ⟨x, hS⟩, ⟨f.fn v x, hS, show Exists _,
by rw [show (f.fn v x :: v) ∘ some = v, from funext $ λs, rfl]; exact ⟨x, rfl⟩⟩⟩
theorem dioph_fn_comp1 {S : set (option α → ℕ)} (d : dioph S) {f : (α → ℕ) → ℕ} (df : dioph_fn f) :
dioph (λv : α → ℕ, S (f v :: v)) :=
ext (dioph_pfun_comp1 d (cast (dioph_fn_iff_pfun f) df)) $ λv,
⟨λ⟨_, h⟩, h, λh, ⟨trivial, h⟩⟩
end
section
variables {α β γ : Type}
open vector3
open_locale vector3
theorem dioph_fn_vec_comp1 {n} {S : set (vector3 ℕ (succ n))} (d : dioph S) {f : (vector3 ℕ n) → ℕ}
(df : dioph_fn f) :
dioph (λv : vector3 ℕ n, S (cons (f v) v)) :=
ext (dioph_fn_comp1 (reindex_dioph d (none :: some)) df) $ λv, by rw [
show option.cons (f v) v ∘ (cons none some) = f v :: v,
from funext $ λs, by cases s with a b; refl]
theorem vec_ex1_dioph (n) {S : set (vector3 ℕ (succ n))} (d : dioph S) :
dioph (λv : vector3 ℕ n, ∃x, S (x :: v)) :=
ext (ex1_dioph $ reindex_dioph d (none :: some)) $ λv, exists_congr $ λx, by rw [
show (option.cons x v) ∘ (cons none some) = x :: v,
from funext $ λs, by cases s with a b; refl]
theorem dioph_fn_vec {n} (f : vector3 ℕ n → ℕ) :
dioph_fn f ↔ dioph (λv : vector3 ℕ (succ n), f (v ∘ fs) = v fz) :=
⟨λh, reindex_dioph h (fz :: fs), λh, reindex_dioph h (none :: some)⟩
theorem dioph_pfun_vec {n} (f : vector3 ℕ n →. ℕ) :
dioph_pfun f ↔ dioph (λv : vector3 ℕ (succ n), f.graph (v ∘ fs, v fz)) :=
⟨λh, reindex_dioph h (fz :: fs), λh, reindex_dioph h (none :: some)⟩
theorem dioph_fn_compn {α : Type} : ∀ {n} {S : set (α ⊕ fin2 n → ℕ)} (d : dioph S)
{f : vector3 ((α → ℕ) → ℕ) n} (df : vector_allp dioph_fn f),
dioph (λv : α → ℕ, S (v ⊗ λi, f i v))
| 0 S d f := λdf, ext (reindex_dioph d (id ⊗ fin2.elim0)) $ λv,
by refine eq.to_iff (congr_arg S $ funext $ λs, _); {cases s with a b, refl, cases b}
| (succ n) S d f := f.cons_elim $ λf fl, by simp; exact λ df dfl,
have dioph (λv, S (v ∘ inl ⊗ f (v ∘ inl) :: v ∘ inr)),
from ext (dioph_fn_comp1 (reindex_dioph d (some ∘ inl ⊗ none :: some ∘ inr))
(reindex_dioph_fn df inl)) $
λv, by {refine eq.to_iff (congr_arg S $ funext $ λs, _); cases s with a b, refl, cases b; refl},
have dioph (λv, S (v ⊗ f v :: λ (i : fin2 n), fl i v)),
from @dioph_fn_compn n (λv, S (v ∘ inl ⊗ f (v ∘ inl) :: v ∘ inr)) this _ dfl,
ext this $ λv, by rw [
show cons (f v) (λ (i : fin2 n), fl i v) = λ (i : fin2 (succ n)), (f :: fl) i v,
from funext $ λs, by cases s with a b; refl]
theorem dioph_comp {n} {S : set (vector3 ℕ n)} (d : dioph S)
(f : vector3 ((α → ℕ) → ℕ) n) (df : vector_allp dioph_fn f) : dioph (λv, S (λi, f i v)) :=
dioph_fn_compn (reindex_dioph d inr) df
theorem dioph_fn_comp {n} {f : vector3 ℕ n → ℕ} (df : dioph_fn f)
(g : vector3 ((α → ℕ) → ℕ) n) (dg : vector_allp dioph_fn g) : dioph_fn (λv, f (λi, g i v)) :=
dioph_comp ((dioph_fn_vec _).1 df) ((λv, v none) :: λi v, g i (v ∘ some)) $
by simp; exact ⟨proj_dioph none, (vector_allp_iff_forall _ _).2 $ λi,
reindex_dioph_fn ((vector_allp_iff_forall _ _).1 dg _) _⟩
localized "notation x ` D∧ `:35 y := dioph.and_dioph x y" in dioph
localized "notation x ` D∨ `:35 y := dioph.or_dioph x y" in dioph
localized "notation `D∃`:30 := dioph.vec_ex1_dioph" in dioph
localized "prefix `&`:max := of_nat'" in dioph
theorem proj_dioph_of_nat {n : ℕ} (m : ℕ) [is_lt m n] : dioph_fn (λv : vector3 ℕ n, v &m) :=
proj_dioph &m
localized "prefix `D&`:100 := dioph.proj_dioph_of_nat" in dioph
theorem const_dioph (n : ℕ) : dioph_fn (const (α → ℕ) n) :=
abs_poly_dioph (poly.const n)
localized "prefix `D.`:100 := dioph.const_dioph" in dioph
variables {f g : (α → ℕ) → ℕ} (df : dioph_fn f) (dg : dioph_fn g)
include df dg
theorem dioph_comp2 {S : ℕ → ℕ → Prop} (d : dioph (λv:vector3 ℕ 2, S (v &0) (v &1))) :
dioph (λv, S (f v) (g v)) :=
dioph_comp d [f, g] (by exact ⟨df, dg⟩)
theorem dioph_fn_comp2 {h : ℕ → ℕ → ℕ} (d : dioph_fn (λv:vector3 ℕ 2, h (v &0) (v &1))) :
dioph_fn (λv, h (f v) (g v)) :=
dioph_fn_comp d [f, g] (by exact ⟨df, dg⟩)
theorem eq_dioph : dioph (λv, f v = g v) :=
dioph_comp2 df dg $ of_no_dummies _ (poly.proj &0 - poly.proj &1)
(λv, (int.coe_nat_eq_coe_nat_iff _ _).symm.trans
⟨@sub_eq_zero_of_eq ℤ _ (v &0) (v &1), eq_of_sub_eq_zero⟩)
localized "infix ` D= `:50 := dioph.eq_dioph" in dioph
theorem add_dioph : dioph_fn (λv, f v + g v) :=
dioph_fn_comp2 df dg $ abs_poly_dioph (poly.proj &0 + poly.proj &1)
localized "infix ` D+ `:80 := dioph.add_dioph" in dioph
theorem mul_dioph : dioph_fn (λv, f v * g v) :=
dioph_fn_comp2 df dg $ abs_poly_dioph (poly.proj &0 * poly.proj &1)
localized "infix ` D* `:90 := dioph.mul_dioph" in dioph
theorem le_dioph : dioph (λv, f v ≤ g v) :=
dioph_comp2 df dg $ ext (D∃2 $ D&1 D+ D&0 D= D&2) (λv, ⟨λ⟨x, hx⟩, le.intro hx, le.dest⟩)
localized "infix ` D≤ `:50 := dioph.le_dioph" in dioph
theorem lt_dioph : dioph (λv, f v < g v) := df D+ (D. 1) D≤ dg
localized "infix ` D< `:50 := dioph.lt_dioph" in dioph
theorem ne_dioph : dioph (λv, f v ≠ g v) :=
ext (df D< dg D∨ dg D< df) $ λv, ne_iff_lt_or_gt.symm
localized "infix ` D≠ `:50 := dioph.ne_dioph" in dioph
theorem sub_dioph : dioph_fn (λv, f v - g v) :=
dioph_fn_comp2 df dg $ (dioph_fn_vec _).2 $
ext (D&1 D= D&0 D+ D&2 D∨ D&1 D≤ D&2 D∧ D&0 D= D.0) $ (vector_all_iff_forall _).1 $ λx y z,
show (y = x + z ∨ y ≤ z ∧ x = 0) ↔ y - z = x, from
⟨λo, begin
rcases o with ae | ⟨yz, x0⟩,
{ rw [ae, nat.add_sub_cancel] },
{ rw [x0, nat.sub_eq_zero_of_le yz] }
end, λh, begin
subst x,
cases le_total y z with yz zy,
{ exact or.inr ⟨yz, nat.sub_eq_zero_of_le yz⟩ },
{ exact or.inl (nat.sub_add_cancel zy).symm },
end⟩
localized "infix ` D- `:80 := dioph.sub_dioph" in dioph
theorem dvd_dioph : dioph (λv, f v ∣ g v) :=
dioph_comp (D∃2 $ D&2 D= D&1 D* D&0) [f, g] (by exact ⟨df, dg⟩)
localized "infix ` D∣ `:50 := dioph.dvd_dioph" in dioph
theorem mod_dioph : dioph_fn (λv, f v % g v) :=
have dioph (λv : vector3 ℕ 3, (v &2 = 0 ∨ v &0 < v &2) ∧ ∃ (x : ℕ), v &0 + v &2 * x = v &1),
from (D&2 D= D.0 D∨ D&0 D< D&2) D∧ (D∃3 $ D&1 D+ D&3 D* D&0 D= D&2),
dioph_fn_comp2 df dg $ (dioph_fn_vec _).2 $ ext this $ (vector_all_iff_forall _).1 $ λz x y,
show ((y = 0 ∨ z < y) ∧ ∃ c, z + y * c = x) ↔ x % y = z, from
⟨λ⟨h, c, hc⟩, begin rw ← hc; simp; cases h with x0 hl, rw [x0, mod_zero], exact mod_eq_of_lt hl end,
λe, by rw ← e; exact ⟨or_iff_not_imp_left.2 $ λh, mod_lt _ (nat.pos_of_ne_zero h), x / y,
mod_add_div _ _⟩⟩
localized "infix ` D% `:80 := dioph.mod_dioph" in dioph
theorem modeq_dioph {h : (α → ℕ) → ℕ} (dh : dioph_fn h) : dioph (λv, f v ≡ g v [MOD h v]) :=
df D% dh D= dg D% dh
localized "notation `D≡` := dioph.modeq_dioph" in dioph
theorem div_dioph : dioph_fn (λv, f v / g v) :=
have dioph (λv : vector3 ℕ 3, v &2 = 0 ∧ v &0 = 0 ∨ v &0 * v &2 ≤ v &1 ∧ v &1 < (v &0 + 1) * v &2),
from (D&2 D= D.0 D∧ D&0 D= D.0) D∨ D&0 D* D&2 D≤ D&1 D∧ D&1 D< (D&0 D+ D.1) D* D&2,
dioph_fn_comp2 df dg $ (dioph_fn_vec _).2 $ ext this $ (vector_all_iff_forall _).1 $ λz x y,
show y = 0 ∧ z = 0 ∨ z * y ≤ x ∧ x < (z + 1) * y ↔ x / y = z,
by refine iff.trans _ eq_comm; exact y.eq_zero_or_pos.elim
(λy0, by rw [y0, nat.div_zero]; exact
⟨λo, (o.resolve_right $ λ⟨_, h2⟩, nat.not_lt_zero _ h2).right, λz0, or.inl ⟨rfl, z0⟩⟩)
(λypos, iff.trans ⟨λo, o.resolve_left $ λ⟨h1, _⟩, ne_of_gt ypos h1, or.inr⟩
(le_antisymm_iff.trans $ and_congr (nat.le_div_iff_mul_le _ _ ypos) $
iff.trans ⟨lt_succ_of_le, le_of_lt_succ⟩ (div_lt_iff_lt_mul _ _ ypos)).symm)
localized "infix ` D/ `:80 := dioph.div_dioph" in dioph
omit df dg
open pell
theorem pell_dioph : dioph (λv:vector3 ℕ 4, ∃ h : 1 < v &0,
xn h (v &1) = v &2 ∧ yn h (v &1) = v &3) :=
have dioph {v : vector3 ℕ 4 |
1 < v &0 ∧ v &1 ≤ v &3 ∧
(v &2 = 1 ∧ v &3 = 0 ∨
∃ (u w s t b : ℕ),
v &2 * v &2 - (v &0 * v &0 - 1) * v &3 * v &3 = 1 ∧
u * u - (v &0 * v &0 - 1) * w * w = 1 ∧
s * s - (b * b - 1) * t * t = 1 ∧
1 < b ∧ (b ≡ 1 [MOD 4 * v &3]) ∧ (b ≡ v &0 [MOD u]) ∧
0 < w ∧ v &3 * v &3 ∣ w ∧
(s ≡ v &2 [MOD u]) ∧
(t ≡ v &1 [MOD 4 * v &3]))}, from
D.1 D< D&0 D∧ D&1 D≤ D&3 D∧
((D&2 D= D.1 D∧ D&3 D= D.0) D∨
(D∃4 $ D∃5 $ D∃6 $ D∃7 $ D∃8 $
D&7 D* D&7 D- (D&5 D* D&5 D- D.1) D* D&8 D* D&8 D= D.1 D∧
D&4 D* D&4 D- (D&5 D* D&5 D- D.1) D* D&3 D* D&3 D= D.1 D∧
D&2 D* D&2 D- (D&0 D* D&0 D- D.1) D* D&1 D* D&1 D= D.1 D∧
D.1 D< D&0 D∧ (D≡ (D&0) (D.1) (D.4 D* D&8)) D∧ (D≡ (D&0) (D&5) D&4) D∧
D.0 D< D&3 D∧ D&8 D* D&8 D∣ D&3 D∧
(D≡ (D&2) (D&7) D&4) D∧
(D≡ (D&1) (D&6) (D.4 D* D&8)))),
dioph.ext this $ λv, matiyasevic.symm
theorem xn_dioph : dioph_pfun (λv:vector3 ℕ 2, ⟨1 < v &0, λh, xn h (v &1)⟩) :=
have dioph (λv:vector3 ℕ 3, ∃ y, ∃ h : 1 < v &1, xn h (v &2) = v &0 ∧ yn h (v &2) = y), from
let D_pell := @reindex_dioph _ (fin2 4) _ pell_dioph [&2, &3, &1, &0] in D∃3 D_pell,
(dioph_pfun_vec _).2 $ dioph.ext this $ λv, ⟨λ⟨y, h, xe, ye⟩, ⟨h, xe⟩, λ⟨h, xe⟩, ⟨_, h, xe, rfl⟩⟩
include df dg
/-- A version of **Matiyasevic's theorem** -/
theorem pow_dioph : dioph_fn (λv, f v ^ g v) :=
have dioph {v : vector3 ℕ 3 |
v &2 = 0 ∧ v &0 = 1 ∨ 0 < v &2 ∧
(v &1 = 0 ∧ v &0 = 0 ∨ 0 < v &1 ∧
∃ (w a t z x y : ℕ),
(∃ (a1 : 1 < a), xn a1 (v &2) = x ∧ yn a1 (v &2) = y) ∧
(x ≡ y * (a - v &1) + v &0 [MOD t]) ∧
2 * a * v &1 = t + (v &1 * v &1 + 1) ∧
v &0 < t ∧ v &1 ≤ w ∧ v &2 ≤ w ∧
a * a - ((w + 1) * (w + 1) - 1) * (w * z) * (w * z) = 1)}, from
let D_pell := @reindex_dioph _ (fin2 9) _ pell_dioph [&4, &8, &1, &0] in
(D&2 D= D.0 D∧ D&0 D= D.1) D∨ (D.0 D< D&2 D∧
((D&1 D= D.0 D∧ D&0 D= D.0) D∨ (D.0 D< D&1 D∧
(D∃3 $ D∃4 $ D∃5 $ D∃6 $ D∃7 $ D∃8 $ D_pell D∧
(D≡ (D&1) (D&0 D* (D&4 D- D&7) D+ D&6) (D&3)) D∧
D.2 D* D&4 D* D&7 D= D&3 D+ (D&7 D* D&7 D+ D.1) D∧
D&6 D< D&3 D∧ D&7 D≤ D&5 D∧ D&8 D≤ D&5 D∧
D&4 D* D&4 D- ((D&5 D+ D.1) D* (D&5 D+ D.1) D- D.1) D* (D&5 D* D&2) D* (D&5 D* D&2) D= D.1)))),
dioph_fn_comp2 df dg $ (dioph_fn_vec _).2 $ dioph.ext this $ λv, iff.symm $
eq_pow_of_pell.trans $ or_congr iff.rfl $ and_congr iff.rfl $ or_congr iff.rfl $ and_congr iff.rfl $
⟨λ⟨w, a, t, z, a1, h⟩, ⟨w, a, t, z, _, _, ⟨a1, rfl, rfl⟩, h⟩,
λ⟨w, a, t, z, ._, ._, ⟨a1, rfl, rfl⟩, h⟩, ⟨w, a, t, z, a1, h⟩⟩
end
end dioph
|
d0f8da0b76ca9d7800489a345467df2e529e1a1f | d1a52c3f208fa42c41df8278c3d280f075eb020c | /stage0/src/Lean/Compiler/IR.lean | 3e6c51ebf4a894704d674ae982b1cd46090024f6 | [
"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 | cipher1024/lean4 | 6e1f98bb58e7a92b28f5364eb38a14c8d0aae393 | 69114d3b50806264ef35b57394391c3e738a9822 | refs/heads/master | 1,642,227,983,603 | 1,642,011,696,000 | 1,642,011,696,000 | 228,607,691 | 0 | 0 | Apache-2.0 | 1,576,584,269,000 | 1,576,584,268,000 | null | UTF-8 | Lean | false | false | 2,948 | 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.Compiler.IR.Basic
import Lean.Compiler.IR.Format
import Lean.Compiler.IR.CompilerM
import Lean.Compiler.IR.PushProj
import Lean.Compiler.IR.ElimDeadVars
import Lean.Compiler.IR.SimpCase
import Lean.Compiler.IR.ResetReuse
import Lean.Compiler.IR.NormIds
import Lean.Compiler.IR.Checker
import Lean.Compiler.IR.Borrow
import Lean.Compiler.IR.Boxing
import Lean.Compiler.IR.RC
import Lean.Compiler.IR.ExpandResetReuse
import Lean.Compiler.IR.UnboxResult
import Lean.Compiler.IR.ElimDeadBranches
import Lean.Compiler.IR.EmitC
import Lean.Compiler.IR.CtorLayout
import Lean.Compiler.IR.Sorry
namespace Lean.IR
register_builtin_option compiler.reuse : Bool := {
defValue := true
descr := "heuristically insert reset/reuse instruction pairs"
}
private def compileAux (decls : Array Decl) : CompilerM Unit := do
logDecls `init decls
checkDecls decls
let mut decls ← elimDeadBranches decls
logDecls `elim_dead_branches decls
decls := decls.map Decl.pushProj
logDecls `push_proj decls
if compiler.reuse.get (← read) then
decls := decls.map Decl.insertResetReuse
logDecls `reset_reuse decls
decls := decls.map Decl.elimDead
logDecls `elim_dead decls
decls := decls.map Decl.simpCase
logDecls `simp_case decls
decls := decls.map Decl.normalizeIds
decls ← inferBorrow decls
logDecls `borrow decls
decls ← explicitBoxing decls
logDecls `boxing decls
decls ← explicitRC decls
logDecls `rc decls
if compiler.reuse.get (← read) then
decls := decls.map Decl.expandResetReuse
logDecls `expand_reset_reuse decls
decls := decls.map Decl.pushProj
logDecls `push_proj decls
decls ← updateSorryDep decls
logDecls `result decls
checkDecls decls
addDecls decls
@[export lean_ir_compile]
def compile (env : Environment) (opts : Options) (decls : Array Decl) : Log × (Except String Environment) :=
match (compileAux decls opts).run { env := env } with
| EStateM.Result.ok _ s => (s.log, Except.ok s.env)
| EStateM.Result.error msg s => (s.log, Except.error msg)
def addBoxedVersionAux (decl : Decl) : CompilerM Unit := do
let env ← getEnv
if !ExplicitBoxing.requiresBoxedVersion env decl then
pure ()
else
let decl := ExplicitBoxing.mkBoxedVersion decl
let decls : Array Decl := #[decl]
let decls ← explicitRC decls
decls.forM fun decl => modifyEnv $ fun env => addDeclAux env decl
pure ()
-- Remark: we are ignoring the `Log` here. This should be fine.
@[export lean_ir_add_boxed_version]
def addBoxedVersion (env : Environment) (decl : Decl) : Except String Environment :=
match (addBoxedVersionAux decl Options.empty).run { env := env } with
| EStateM.Result.ok _ s => Except.ok s.env
| EStateM.Result.error msg s => Except.error msg
end Lean.IR
|
78564142de3686912e0e1023a5508e300be3f09e | 367134ba5a65885e863bdc4507601606690974c1 | /src/topology/category/TopCommRing.lean | 035577994bbdfaaddbbd9148076d5cbd847bbc00 | [
"Apache-2.0"
] | permissive | kodyvajjha/mathlib | 9bead00e90f68269a313f45f5561766cfd8d5cad | b98af5dd79e13a38d84438b850a2e8858ec21284 | refs/heads/master | 1,624,350,366,310 | 1,615,563,062,000 | 1,615,563,062,000 | 162,666,963 | 0 | 0 | Apache-2.0 | 1,545,367,651,000 | 1,545,367,651,000 | null | UTF-8 | Lean | false | false | 3,562 | 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 algebra.category.CommRing.basic
import topology.category.Top.basic
import topology.algebra.ring
/-!
# Category of topological commutative rings
We introduce the category `TopCommRing` of topological commutative rings together with the relevant
forgetful functors to topological spaces and commutative rings.
-/
universes u
open category_theory
/-- A bundled topological commutative ring. -/
structure TopCommRing :=
(α : Type u)
[is_comm_ring : comm_ring α]
[is_topological_space : topological_space α]
[is_topological_ring : topological_ring α]
namespace TopCommRing
instance : has_coe_to_sort TopCommRing :=
{ S := Type u, coe := TopCommRing.α }
attribute [instance] is_comm_ring is_topological_space is_topological_ring
instance : category TopCommRing.{u} :=
{ hom := λ R S, {f : R →+* S // continuous f },
id := λ R, ⟨ring_hom.id R, by obviously⟩, -- TODO remove obviously?
comp := λ R S T f g, ⟨g.val.comp f.val,
begin -- TODO automate
cases f, cases g,
dsimp, apply continuous.comp ; assumption
end⟩ }
instance : concrete_category TopCommRing.{u} :=
{ forget := { obj := λ R, R, map := λ R S f, f.val },
forget_faithful := { } }
/-- Construct a bundled `TopCommRing` from the underlying type and the appropriate typeclasses. -/
def of (X : Type u) [comm_ring X] [topological_space X] [topological_ring X] : TopCommRing := ⟨X⟩
@[simp] lemma coe_of (X : Type u) [comm_ring X] [topological_space X] [topological_ring X] :
(of X : Type u) = X := rfl
instance forget_topological_space (R : TopCommRing) :
topological_space ((forget TopCommRing).obj R) :=
R.is_topological_space
instance forget_comm_ring (R : TopCommRing) :
comm_ring ((forget TopCommRing).obj R) :=
R.is_comm_ring
instance forget_topological_ring (R : TopCommRing) :
topological_ring ((forget TopCommRing).obj R) :=
R.is_topological_ring
instance has_forget_to_CommRing : has_forget₂ TopCommRing CommRing :=
has_forget₂.mk'
(λ R, CommRing.of R)
(λ x, rfl)
(λ R S f, f.val)
(λ R S f, heq.rfl)
instance forget_to_CommRing_topological_space (R : TopCommRing) :
topological_space ((forget₂ TopCommRing CommRing).obj R) :=
R.is_topological_space
/-- The forgetful functor to Top. -/
instance has_forget_to_Top : has_forget₂ TopCommRing Top :=
has_forget₂.mk'
(λ R, Top.of R)
(λ x, rfl)
(λ R S f, ⟨⇑f.1, f.2⟩)
(λ R S f, heq.rfl)
instance forget_to_Top_comm_ring (R : TopCommRing) :
comm_ring ((forget₂ TopCommRing Top).obj R) :=
R.is_comm_ring
instance forget_to_Top_topological_ring (R : TopCommRing) :
topological_ring ((forget₂ TopCommRing Top).obj R) :=
R.is_topological_ring
/--
The forgetful functors to `Type` do not reflect isomorphisms,
but the forgetful functor from `TopCommRing` to `Top` does.
-/
instance : reflects_isomorphisms (forget₂ TopCommRing Top) :=
{ reflects := λ X Y f _,
begin
resetI,
-- We have an isomorphism in `Top`,
let i_Top := as_iso ((forget₂ TopCommRing Top).map f),
-- and a `ring_equiv`.
let e_Ring : X ≃+* Y := { ..f.1, ..((forget Top).map_iso i_Top).to_equiv },
-- Putting these together we obtain the isomorphism we're after:
exact
{ inv := ⟨e_Ring.symm, i_Top.inv.2⟩,
hom_inv_id' := by { ext x, exact e_Ring.left_inv x, },
inv_hom_id' := by { ext x, exact e_Ring.right_inv x, }, },
end }
end TopCommRing
|
ca6810dc151e6af2173892d8282a4c6cc657ed5e | efce24474b28579aba3272fdb77177dc2b11d7aa | /src/homotopy_theory/topological_spaces/interval_endpoints.lean | dcff1e18298382ad2174a5f93fbb515ee63f50aa | [
"Apache-2.0"
] | permissive | rwbarton/lean-homotopy-theory | cff499f24268d60e1c546e7c86c33f58c62888ed | 39e1b4ea1ed1b0eca2f68bc64162dde6a6396dee | refs/heads/lean-3.4.2 | 1,622,711,883,224 | 1,598,550,958,000 | 1,598,550,958,000 | 136,023,667 | 12 | 6 | Apache-2.0 | 1,573,187,573,000 | 1,528,116,262,000 | Lean | UTF-8 | Lean | false | false | 3,216 | lean | import category_theory.isomorphism
import .category
import .colimits
import .cylinder
import .distrib
import .homeomorphism
noncomputable theory
open set
open category_theory
namespace homotopy_theory.topological_spaces
open homotopy_theory.topological_spaces.Top
local notation `Top` := Top.{0}
-- The set of endpoints of the unit interval, as a space.
def I01_endpoints : Top := Top.mk_ob ({0, 1} : set I01)
instance I01_endpoints.has_zero : has_zero I01_endpoints := ⟨⟨0, by simp⟩⟩
instance I01_endpoints.has_one : has_one I01_endpoints := ⟨⟨1, by simp⟩⟩
instance Top.point.discrete_topology : discrete_topology Top.point :=
⟨eq_bot_of_singletons_open (λ ⟨⟩, by convert is_open_univ; ext p; cases p; simp)⟩
def two_endpoints : homeomorphism (* ⊔ *) I01_endpoints :=
let j : * ⊔ * ⟶ I01 :=
coprod.induced
(Top.mk_hom (λ _, 0) (by continuity))
(Top.mk_hom (λ _, 1) (by continuity)) in
have rj : range j = ({0, 1} : set I01), begin -- FIXME annotation should be unnecessary
ext p, split,
{ intro h, rcases h with ⟨⟨⟨⟩⟩|⟨⟨⟩⟩, rfl⟩,
{ change (0 : I01) ∈ _, simp }, { change (1 : I01) ∈ _, simp } },
{ intro h, have : p = 0 ∨ p = 1, by simp at h; exact h,
cases this,
{ subst this, exact ⟨sum.inl punit.star, rfl⟩ },
{ subst this, exact ⟨sum.inr punit.star, rfl⟩ } }
end,
have function.injective j, begin
intros a b h, rcases a with ⟨⟨⟩⟩|⟨⟨⟩⟩; rcases b with ⟨⟨⟩⟩|⟨⟨⟩⟩,
any_goals { refl },
{ change (0 : I01) = 1 at h,
have h' : (0 : ℝ) = 1 := congr_arg subtype.val h,
simpa using h' },
{ change (1 : I01) = 0 at h,
have h' : (1 : ℝ) = 0 := congr_arg subtype.val h,
simpa using h' }
end,
have embedding j, begin
refine ⟨⟨_⟩, this⟩,
change sum.topological_space = _,
refine sum.discrete_topology.eq_bot.trans _,
symmetry,
apply eq_bot_of_singletons_open, intro e,
rcases e with ⟨⟨⟩⟩|⟨⟨⟩⟩,
{ refine ⟨{t : I01 | t.val < 1},
is_open_lt continuous_subtype_val continuous_const, _⟩,
ext p, split,
{ intro h, rcases p with ⟨⟨⟩⟩|⟨⟨⟩⟩, { simp },
{ change (1 : ℝ) < 1 at h, have : ¬((1 : ℝ) < 1), by norm_num,
contradiction } },
{ intro h, simp at h, subst p, change (0 : ℝ) < 1, norm_num } },
{ refine ⟨{t : I01 | t.val > 0},
is_open_lt continuous_const continuous_subtype_val, _⟩,
ext p, split,
{ intro h, rcases p with ⟨⟨⟩⟩|⟨⟨⟩⟩,
{ change (0 : ℝ) > 0 at h, have : ¬((0 : ℝ) > 0), by norm_num,
contradiction },
{ simp } },
{ intro h, simp at h, subst p, change (1 : ℝ) > 0, norm_num } }
end,
(homeomorphism_to_image_of_embedding this).trans
(subspace_equiv_subspace rj)
def prod_doubleton {X : Top} : homeomorphism (∂I.obj X) (Top.prod X I01_endpoints) :=
calc
∂I.obj X
≅ ∂I.obj (Top.prod X Top.point)
: (∂I).map_iso (prod_singleton (by refl))
... ≅ Top.prod X Top.point ⊔ Top.prod X Top.point
: by refl
... ≅ Top.prod X (* ⊔ *)
: Top.prod.distrib
... ≅ Top.prod X I01_endpoints
: two_endpoints.prod_congr_right
end homotopy_theory.topological_spaces
|
0ec412c57dd18c2aa0f383ca34a4d1628171fb27 | 359199d7253811b032ab92108191da7336eba86e | /src/mywork/work.lean | ede56c488034bc9a1aa18a992e90bb9af62c010f | [] | no_license | arte-et-marte/my_cs2120f21 | 0bc6215cb5018a3b7c90d9d399a173233f587064 | 91609c3609ad81fda895bee8b97cc76813241e17 | refs/heads/main | 1,693,298,928,348 | 1,634,931,202,000 | 1,634,931,202,000 | 399,946,705 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 190 | lean | axiom P : ∀ ( P : Prop ), ¬(P ∧ ¬P)
-- "No proposition can be both true and false."
-- "For any proposition P, P is either true or not true."
P ∨ ¬P -- axiom of the excluded middle |
35517b45410ba6dc1ca5cbeebf084f8fe4c0c060 | 57c233acf9386e610d99ed20ef139c5f97504ba3 | /src/category_theory/preadditive/default.lean | cf257c117d85b9829f23ab2cd0d8720d2149838b | [
"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 | 9,620 | lean | /-
Copyright (c) 2020 Markus Himmel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Markus Himmel
-/
import algebra.group.hom
import category_theory.limits.shapes.kernels
import algebra.big_operators.basic
import algebra.module.basic
import category_theory.endomorphism
/-!
# Preadditive categories
A preadditive category is a category in which `X ⟶ Y` is an abelian group in such a way that
composition of morphisms is linear in both variables.
This file contains a definition of preadditive category that directly encodes the definition given
above. The definition could also be phrased as follows: A preadditive category is a category
enriched over the category of Abelian groups. Once the general framework to state this in Lean is
available, the contents of this file should become obsolete.
## Main results
* Definition of preadditive categories and basic properties
* In a preadditive category, `f : Q ⟶ R` is mono if and only if `g ≫ f = 0 → g = 0` for all
composable `g`.
* A preadditive category with kernels has equalizers.
## Implementation notes
The simp normal form for negation and composition is to push negations as far as possible to
the outside. For example, `f ≫ (-g)` and `(-f) ≫ g` both become `-(f ≫ g)`, and `(-f) ≫ (-g)`
is simplified to `f ≫ g`.
## References
* [F. Borceux, *Handbook of Categorical Algebra 2*][borceux-vol2]
## Tags
additive, preadditive, Hom group, Ab-category, Ab-enriched
-/
universes v u
open category_theory.limits
open_locale big_operators
namespace category_theory
variables (C : Type u) [category.{v} C]
/-- A category is called preadditive if `P ⟶ Q` is an abelian group such that composition is
linear in both variables. -/
class preadditive :=
(hom_group : Π P Q : C, add_comm_group (P ⟶ Q) . tactic.apply_instance)
(add_comp' : ∀ (P Q R : C) (f f' : P ⟶ Q) (g : Q ⟶ R),
(f + f') ≫ g = f ≫ g + f' ≫ g . obviously)
(comp_add' : ∀ (P Q R : C) (f : P ⟶ Q) (g g' : Q ⟶ R),
f ≫ (g + g') = f ≫ g + f ≫ g' . obviously)
attribute [instance] preadditive.hom_group
restate_axiom preadditive.add_comp'
restate_axiom preadditive.comp_add'
attribute [simp,reassoc] preadditive.add_comp
attribute [reassoc] preadditive.comp_add -- (the linter doesn't like `simp` on this lemma)
attribute [simp] preadditive.comp_add
end category_theory
open category_theory
namespace category_theory
namespace preadditive
section preadditive
open add_monoid_hom
variables {C : Type u} [category.{v} C] [preadditive C]
section induced_category
universes u'
variables {C} {D : Type u'} (F : D → C)
instance induced_category.category : preadditive.{v} (induced_category C F) :=
{ hom_group := λ P Q, @preadditive.hom_group C _ _ (F P) (F Q),
add_comp' := λ P Q R f f' g, add_comp' _ _ _ _ _ _,
comp_add' := λ P Q R f g g', comp_add' _ _ _ _ _ _, }
end induced_category
instance (X : C) : add_comm_group (End X) := by { dsimp [End], apply_instance, }
instance (X : C) : ring (End X) :=
{ left_distrib := λ f g h, preadditive.add_comp X X X g h f,
right_distrib := λ f g h, preadditive.comp_add X X X h f g,
..(infer_instance : add_comm_group (End X)),
..(infer_instance : monoid (End X)) }
/-- Composition by a fixed left argument as a group homomorphism -/
def left_comp {P Q : C} (R : C) (f : P ⟶ Q) : (Q ⟶ R) →+ (P ⟶ R) :=
mk' (λ g, f ≫ g) $ λ g g', by simp
/-- Composition by a fixed right argument as a group homomorphism -/
def right_comp (P : C) {Q R : C} (g : Q ⟶ R) : (P ⟶ Q) →+ (P ⟶ R) :=
mk' (λ f, f ≫ g) $ λ f f', by simp
variables {P Q R : C} (f f' : P ⟶ Q) (g g' : Q ⟶ R)
/-- Composition as a bilinear group homomorphism -/
def comp_hom : (P ⟶ Q) →+ (Q ⟶ R) →+ (P ⟶ R) :=
add_monoid_hom.mk' (λ f, left_comp _ f) $
λ f₁ f₂, add_monoid_hom.ext $ λ g, (right_comp _ g).map_add f₁ f₂
@[simp, reassoc] lemma sub_comp :
(f - f') ≫ g = f ≫ g - f' ≫ g :=
map_sub (right_comp P g) f f'
-- The redundant simp lemma linter says that simp can prove the reassoc version of this lemma.
@[reassoc, simp] lemma comp_sub :
f ≫ (g - g') = f ≫ g - f ≫ g' :=
map_sub (left_comp R f) g g'
@[simp, reassoc] lemma neg_comp : (-f) ≫ g = -(f ≫ g) :=
map_neg (right_comp P g) f
/- The redundant simp lemma linter says that simp can prove the reassoc version of this lemma. -/
@[reassoc, simp] lemma comp_neg : f ≫ (-g) = -(f ≫ g) :=
map_neg (left_comp R f) g
@[reassoc] lemma neg_comp_neg : (-f) ≫ (-g) = f ≫ g :=
by simp
lemma nsmul_comp (n : ℕ) : (n • f) ≫ g = n • (f ≫ g) :=
map_nsmul (right_comp P g) f n
lemma comp_nsmul (n : ℕ) : f ≫ (n • g) = n • (f ≫ g) :=
map_nsmul (left_comp R f) g n
lemma zsmul_comp (n : ℤ) : (n • f) ≫ g = n • (f ≫ g) :=
map_zsmul (right_comp P g) f n
lemma comp_zsmul (n : ℤ) : f ≫ (n • g) = n • (f ≫ g) :=
map_zsmul (left_comp R f) g n
@[reassoc] lemma comp_sum {P Q R : C} {J : Type*} (s : finset J) (f : P ⟶ Q) (g : J → (Q ⟶ R)) :
f ≫ ∑ j in s, g j = ∑ j in s, f ≫ g j :=
map_sum (left_comp R f) _ _
@[reassoc] lemma sum_comp {P Q R : C} {J : Type*} (s : finset J) (f : J → (P ⟶ Q)) (g : Q ⟶ R) :
(∑ j in s, f j) ≫ g = ∑ j in s, f j ≫ g :=
map_sum (right_comp P g) _ _
instance {P Q : C} {f : P ⟶ Q} [epi f] : epi (-f) :=
⟨λ R g g' H, by rwa [neg_comp, neg_comp, ←comp_neg, ←comp_neg, cancel_epi, neg_inj] at H⟩
instance {P Q : C} {f : P ⟶ Q} [mono f] : mono (-f) :=
⟨λ R g g' H, by rwa [comp_neg, comp_neg, ←neg_comp, ←neg_comp, cancel_mono, neg_inj] at H⟩
@[priority 100]
instance preadditive_has_zero_morphisms : has_zero_morphisms C :=
{ has_zero := infer_instance,
comp_zero' := λ P Q f R, show left_comp R f 0 = 0, from map_zero _,
zero_comp' := λ P Q R f, show right_comp P f 0 = 0, from map_zero _ }
instance module_End_right {X Y : C} : module (End Y) (X ⟶ Y) :=
{ smul_add := λ r f g, add_comp _ _ _ _ _ _,
smul_zero := λ r, zero_comp,
add_smul := λ r s f, comp_add _ _ _ _ _ _,
zero_smul := λ r, comp_zero }
lemma mono_of_cancel_zero {Q R : C} (f : Q ⟶ R) (h : ∀ {P : C} (g : P ⟶ Q), g ≫ f = 0 → g = 0) :
mono f :=
⟨λ P g g' hg, sub_eq_zero.1 $ h _ $ (map_sub (right_comp P f) g g').trans $ sub_eq_zero.2 hg⟩
lemma mono_iff_cancel_zero {Q R : C} (f : Q ⟶ R) :
mono f ↔ ∀ (P : C) (g : P ⟶ Q), g ≫ f = 0 → g = 0 :=
⟨λ m P g, by exactI zero_of_comp_mono _, mono_of_cancel_zero f⟩
lemma mono_of_kernel_zero {X Y : C} {f : X ⟶ Y} [has_limit (parallel_pair f 0)]
(w : kernel.ι f = 0) : mono f :=
mono_of_cancel_zero f (λ P g h, by rw [←kernel.lift_ι f g h, w, limits.comp_zero])
lemma epi_of_cancel_zero {P Q : C} (f : P ⟶ Q) (h : ∀ {R : C} (g : Q ⟶ R), f ≫ g = 0 → g = 0) :
epi f :=
⟨λ R g g' hg, sub_eq_zero.1 $ h _ $ (map_sub (left_comp R f) g g').trans $ sub_eq_zero.2 hg⟩
lemma epi_iff_cancel_zero {P Q : C} (f : P ⟶ Q) :
epi f ↔ ∀ (R : C) (g : Q ⟶ R), f ≫ g = 0 → g = 0 :=
⟨λ e R g, by exactI zero_of_epi_comp _, epi_of_cancel_zero f⟩
lemma epi_of_cokernel_zero {X Y : C} {f : X ⟶ Y} [has_colimit (parallel_pair f 0 )]
(w : cokernel.π f = 0) : epi f :=
epi_of_cancel_zero f (λ P g h, by rw [←cokernel.π_desc f g h, w, limits.zero_comp])
open_locale zero_object
variables [has_zero_object C]
lemma mono_of_kernel_iso_zero {X Y : C} {f : X ⟶ Y} [has_limit (parallel_pair f 0)]
(w : kernel f ≅ 0) : mono f :=
mono_of_kernel_zero (zero_of_source_iso_zero _ w)
lemma epi_of_cokernel_iso_zero {X Y : C} {f : X ⟶ Y} [has_colimit (parallel_pair f 0)]
(w : cokernel f ≅ 0) : epi f :=
epi_of_cokernel_zero (zero_of_target_iso_zero _ w)
end preadditive
section equalizers
variables {C : Type u} [category.{v} C] [preadditive C]
section
variables {X Y : C} (f : X ⟶ Y) (g : X ⟶ Y)
/-- A kernel of `f - g` is an equalizer of `f` and `g`. -/
lemma has_limit_parallel_pair [has_kernel (f - g)] :
has_limit (parallel_pair f g) :=
has_limit.mk { cone := fork.of_ι (kernel.ι (f - g)) (sub_eq_zero.1 $
by { rw ←comp_sub, exact kernel.condition _ }),
is_limit := fork.is_limit.mk _
(λ s, kernel.lift (f - g) (fork.ι s) $
by { rw comp_sub, apply sub_eq_zero.2, exact fork.condition _ })
(λ s, by simp)
(λ s m h, by { ext, simpa using h walking_parallel_pair.zero }) }
end
section
/-- If a preadditive category has all kernels, then it also has all equalizers. -/
lemma has_equalizers_of_has_kernels [has_kernels C] : has_equalizers C :=
@has_equalizers_of_has_limit_parallel_pair _ _ (λ _ _ f g, has_limit_parallel_pair f g)
end
section
variables {X Y : C} (f : X ⟶ Y) (g : X ⟶ Y)
/-- A cokernel of `f - g` is a coequalizer of `f` and `g`. -/
lemma has_colimit_parallel_pair [has_cokernel (f - g)] :
has_colimit (parallel_pair f g) :=
has_colimit.mk { cocone := cofork.of_π (cokernel.π (f - g)) (sub_eq_zero.1 $
by { rw ←sub_comp, exact cokernel.condition _ }),
is_colimit := cofork.is_colimit.mk _
(λ s, cokernel.desc (f - g) (cofork.π s) $
by { rw sub_comp, apply sub_eq_zero.2, exact cofork.condition _ })
(λ s, by simp)
(λ s m h, by { ext, simpa using h walking_parallel_pair.one }) }
end
section
/-- If a preadditive category has all cokernels, then it also has all coequalizers. -/
lemma has_coequalizers_of_has_cokernels [has_cokernels C] : has_coequalizers C :=
@has_coequalizers_of_has_colimit_parallel_pair _ _ (λ _ _ f g, has_colimit_parallel_pair f g)
end
end equalizers
end preadditive
end category_theory
|
85ada4f7e7d9f234ec0e0ca861b48c5756a21296 | 46ee5dc7248ccc9ee615639c0c003c05f58975cd | /src/modelgraphs.lean | a06075fe3c97d6b9055f3df94e883090388a75bc | [
"Apache-2.0"
] | permissive | m4lvin/tablean | e61d593b4dde6512245192c577edeb36c48f63c0 | 836202612fc2bfacb5545696412e7d27f7704141 | refs/heads/main | 1,685,613,112,076 | 1,676,755,678,000 | 1,676,755,678,000 | 454,064,275 | 8 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 4,433 | lean | -- MODELGRAPHS
import syntax
import semantics
open formula
-- Definition 18, page 31
def saturated : finset formula → Prop
| X := ∀ P Q : formula,
( ~~P ∈ X → P ∈ X ) ∧
( P⋏Q ∈ X → P ∈ X ∧ Q ∈ X ) ∧
( ~(P⋏Q) ∈ X → ~P ∈ X ∨ ~Q ∈ X )
-- TODO: closure for program combinators!
-- Definition 19, page 31
-- TODO: change [] to [A] later
@[simp]
def modelGraph ( Worlds : finset (finset formula) ) :=
let
W := subtype (λ x, x ∈ Worlds),
i := ∀ X : W, saturated X.val ∧ ⊥ ∉ X.val ∧ (∀ P, P ∈ X.val → ~P ∉ X.val),
ii := λ M : kripkeModel W, (∀ (X : W) pp, ((·pp) ∈ X.val ↔ M.val X pp)),
-- Note: Borzechowski only has → in ii. We follow BRV, Def 4.18 and 4.84.
iii := λ M : kripkeModel W, ∀ (X Y : W) P, M.rel X Y → □P ∈ X.val → P ∈ Y.val,
iv := λ M : kripkeModel W, ∀ (X : W) P, ~□P ∈ X.val → ∃ Y, M.rel X Y ∧ ~P ∈ Y.val
in subtype ( λ M : kripkeModel W , i ∧ ii M ∧ iii M ∧ iv M )
-- Lemma 9, page 32
lemma truthLemma { Worlds : finset (finset formula) } (MG : modelGraph Worlds) :
∀ X : Worlds, ∀ P, P ∈ X.val → evaluate (MG.val,X) P :=
begin
intros X P,
cases MG with M M_prop,
rcases M_prop with ⟨ i, ii, iii, iv ⟩,
-- induction loading!!
let plus := λ P (X : Worlds), P ∈ X.val → evaluate (M,X) P,
let minus := λ P (X : Worlds), ~P ∈ X.val → ¬ evaluate (M,X) P,
let oh := λ P (X : Worlds), □P ∈ X.val → ∀ Y, M.rel X Y → P ∈ Y.val,
have claim : ∀ P X, plus P X ∧ minus P X ∧ oh P X, {
intro P,
induction P, all_goals { intro X, },
case bottom : {
specialize i X,
rcases i with ⟨_, bot_not_in_X, _ ⟩,
repeat { split },
{ intro P_in_X, apply absurd P_in_X bot_not_in_X, },
{ intro notP_in_X, tauto, },
{ intros boxBot_in_X Y X_rel_Y, exact iii X Y ⊥ X_rel_Y boxBot_in_X },
},
case atom_prop : pp {
repeat { split },
{ intro P_in_X, unfold evaluate, rw (ii X pp) at P_in_X, exact P_in_X, },
{ intro notP_in_X, unfold evaluate, rw ← ii X pp,
rcases i X with ⟨ _, _, P_in_then_notP_not_in ⟩,
specialize P_in_then_notP_not_in (· pp), tauto, },
{ intros boxPp_in_X Y X_rel_Y, exact iii X Y (· pp) X_rel_Y boxPp_in_X, },
},
case neg : P IH {
rcases IH X with ⟨ plus_IH, minus_IH, oh_OH ⟩,
repeat { split },
{ intro notP_in_X, unfold evaluate,
exact minus_IH notP_in_X, },
{ intro notnotP_in_X,
rcases i X with ⟨X_saturated, _, _ ⟩,
cases X_saturated P ⊥ with doubleNeg, -- ⊥ is unused!
unfold evaluate, simp,
exact plus_IH (doubleNeg notnotP_in_X),
},
{ intros notPp_in_X Y X_rel_Y, exact iii X Y (~P) X_rel_Y notPp_in_X, },
},
case and : P Q IH_P IH_Q {
rcases IH_P X with ⟨ plus_IH_P, minus_IH_P, oh_P ⟩,
rcases IH_Q X with ⟨ plus_IH_Q, minus_IH_Q, oh_Q ⟩,
rcases i X with ⟨X_saturated, _, _ ⟩,
unfold saturated at X_saturated,
rcases X_saturated P Q with ⟨ doubleNeg, andSplit, notAndSplit ⟩,
repeat { split },
{ intro PandQ_in_X,
specialize andSplit PandQ_in_X, cases andSplit with P_in_X Q_in_X,
unfold evaluate,
split, { exact plus_IH_P P_in_X }, { exact plus_IH_Q Q_in_X, } },
{ intro notPandQ_in_X,
unfold evaluate, rw not_and_distrib,
specialize notAndSplit notPandQ_in_X,
cases notAndSplit with notP_in_X notQ_in_X,
{ left, exact minus_IH_P notP_in_X },
{ right, exact minus_IH_Q notQ_in_X, },
},
{ intros PandQ_in_X Y X_rel_Y, exact iii X Y (P ⋏ Q) X_rel_Y PandQ_in_X, }
},
case box : P IH {
repeat { split },
{ intro boxP_in_X, unfold evaluate,
intros Y X_rel_Y,
rcases IH Y with ⟨ plus_IH_Y, _, _ ⟩,
apply plus_IH_Y,
rcases IH X with ⟨ _, _, oh_IH_X ⟩,
exact oh_IH_X boxP_in_X Y X_rel_Y, },
{ intro notBoxP_in_X, unfold evaluate,
push_neg,
rcases iv X P notBoxP_in_X with ⟨ Y, X_rel_Y, notP_in_Y ⟩,
use Y, split, exact X_rel_Y,
rcases IH Y with ⟨ _, minus_IH_Y, _ ⟩,
exact minus_IH_Y notP_in_Y, },
{ intros boxBoxP_in_X Y X_rel_Y, exact iii X Y (□P) X_rel_Y boxBoxP_in_X, }
},
},
apply (claim P X).left,
end
|
6827788d7516a5349137ae46d02cc512fde152d3 | d9d511f37a523cd7659d6f573f990e2a0af93c6f | /src/order/filter/extr.lean | 2bb6a8b75f4470183d824e3856b3422e6e7a0b1c | [
"Apache-2.0"
] | permissive | hikari0108/mathlib | b7ea2b7350497ab1a0b87a09d093ecc025a50dfa | a9e7d333b0cfd45f13a20f7b96b7d52e19fa2901 | refs/heads/master | 1,690,483,608,260 | 1,631,541,580,000 | 1,631,541,580,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 21,252 | lean | /-
Copyright (c) 2019 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import order.filter.basic
/-!
# Minimum and maximum w.r.t. a filter and on a aet
## Main Definitions
This file defines six predicates of the form `is_A_B`, where `A` is `min`, `max`, or `extr`,
and `B` is `filter` or `on`.
* `is_min_filter f l a` means that `f a ≤ f x` in some `l`-neighborhood of `a`;
* `is_max_filter f l a` means that `f x ≤ f a` in some `l`-neighborhood of `a`;
* `is_extr_filter f l a` means `is_min_filter f l a` or `is_max_filter f l a`.
Similar predicates with `_on` suffix are particular cases for `l = 𝓟 s`.
## Main statements
### Change of the filter (set) argument
* `is_*_filter.filter_mono` : replace the filter with a smaller one;
* `is_*_filter.filter_inf` : replace a filter `l` with `l ⊓ l'`;
* `is_*_on.on_subset` : restrict to a smaller set;
* `is_*_on.inter` : replace a set `s` wtih `s ∩ t`.
### Composition
* `is_*_*.comp_mono` : if `x` is an extremum for `f` and `g` is a monotone function,
then `x` is an extremum for `g ∘ f`;
* `is_*_*.comp_antimono` : similarly for the case of monotonically decreasing `g`;
* `is_*_*.bicomp_mono` : if `x` is an extremum of the same type for `f` and `g`
and a binary operation `op` is monotone in both arguments, then `x` is an extremum
of the same type for `λ x, op (f x) (g x)`.
* `is_*_filter.comp_tendsto` : if `g x` is an extremum for `f` w.r.t. `l'` and `tendsto g l l'`,
then `x` is an extremum for `f ∘ g` w.r.t. `l`.
* `is_*_on.on_preimage` : if `g x` is an extremum for `f` on `s`, then `x` is an extremum
for `f ∘ g` on `g ⁻¹' s`.
### Algebraic operations
* `is_*_*.add` : if `x` is an extremum of the same type for two functions,
then it is an extremum of the same type for their sum;
* `is_*_*.neg` : if `x` is an extremum for `f`, then it is an extremum
of the opposite type for `-f`;
* `is_*_*.sub` : if `x` is an a minimum for `f` and a maximum for `g`,
then it is a minimum for `f - g` and a maximum for `g - f`;
* `is_*_*.max`, `is_*_*.min`, `is_*_*.sup`, `is_*_*.inf` : similarly for `is_*_*.add`
for pointwise `max`, `min`, `sup`, `inf`, respectively.
### Miscellaneous definitions
* `is_*_*_const` : any point is both a minimum and maximum for a constant function;
* `is_min/max_*.is_ext` : any minimum/maximum point is an extremum;
* `is_*_*.dual`, `is_*_*.undual`: conversion between codomains `α` and `dual α`;
## Missing features (TODO)
* Multiplication and division;
* `is_*_*.bicompl` : if `x` is a minimum for `f`, `y` is a minimum for `g`, and `op` is a monotone
binary operation, then `(x, y)` is a minimum for `uncurry (bicompl op f g)`. From this point
of view, `is_*_*.bicomp` is a composition
* It would be nice to have a tactic that specializes `comp_(anti)mono` or `bicomp_mono`
based on a proof of monotonicity of a given (binary) function. The tactic should maintain a `meta`
list of known (anti)monotone (binary) functions with their names, as well as a list of special
types of filters, and define the missing lemmas once one of these two lists grows.
-/
universes u v w x
variables {α : Type u} {β : Type v} {γ : Type w} {δ : Type x}
open set filter
open_locale filter
section preorder
variables [preorder β] [preorder γ]
variables (f : α → β) (s : set α) (l : filter α) (a : α)
/-! ### Definitions -/
/-- `is_min_filter f l a` means that `f a ≤ f x` in some `l`-neighborhood of `a` -/
def is_min_filter : Prop := ∀ᶠ x in l, f a ≤ f x
/-- `is_max_filter f l a` means that `f x ≤ f a` in some `l`-neighborhood of `a` -/
def is_max_filter : Prop := ∀ᶠ x in l, f x ≤ f a
/-- `is_extr_filter f l a` means `is_min_filter f l a` or `is_max_filter f l a` -/
def is_extr_filter : Prop := is_min_filter f l a ∨ is_max_filter f l a
/-- `is_min_on f s a` means that `f a ≤ f x` for all `x ∈ a`. Note that we do not assume `a ∈ s`. -/
def is_min_on := is_min_filter f (𝓟 s) a
/-- `is_max_on f s a` means that `f x ≤ f a` for all `x ∈ a`. Note that we do not assume `a ∈ s`. -/
def is_max_on := is_max_filter f (𝓟 s) a
/-- `is_extr_on f s a` means `is_min_on f s a` or `is_max_on f s a` -/
def is_extr_on : Prop := is_extr_filter f (𝓟 s) a
variables {f s a l} {t : set α} {l' : filter α}
lemma is_extr_on.elim {p : Prop} :
is_extr_on f s a → (is_min_on f s a → p) → (is_max_on f s a → p) → p :=
or.elim
lemma is_min_on_iff : is_min_on f s a ↔ ∀ x ∈ s, f a ≤ f x := iff.rfl
lemma is_max_on_iff : is_max_on f s a ↔ ∀ x ∈ s, f x ≤ f a := iff.rfl
lemma is_min_on_univ_iff : is_min_on f univ a ↔ ∀ x, f a ≤ f x :=
univ_subset_iff.trans eq_univ_iff_forall
lemma is_max_on_univ_iff : is_max_on f univ a ↔ ∀ x, f x ≤ f a :=
univ_subset_iff.trans eq_univ_iff_forall
lemma is_min_filter.tendsto_principal_Ici (h : is_min_filter f l a) :
tendsto f l (𝓟 $ Ici (f a)) :=
tendsto_principal.2 h
lemma is_max_filter.tendsto_principal_Iic (h : is_max_filter f l a) :
tendsto f l (𝓟 $ Iic (f a)) :=
tendsto_principal.2 h
/-! ### Conversion to `is_extr_*` -/
lemma is_min_filter.is_extr : is_min_filter f l a → is_extr_filter f l a := or.inl
lemma is_max_filter.is_extr : is_max_filter f l a → is_extr_filter f l a := or.inr
lemma is_min_on.is_extr (h : is_min_on f s a) : is_extr_on f s a := h.is_extr
lemma is_max_on.is_extr (h : is_max_on f s a) : is_extr_on f s a := h.is_extr
/-! ### Constant function -/
lemma is_min_filter_const {b : β} : is_min_filter (λ _, b) l a :=
univ_mem' $ λ _, le_refl _
lemma is_max_filter_const {b : β} : is_max_filter (λ _, b) l a :=
univ_mem' $ λ _, le_refl _
lemma is_extr_filter_const {b : β} : is_extr_filter (λ _, b) l a := is_min_filter_const.is_extr
lemma is_min_on_const {b : β} : is_min_on (λ _, b) s a := is_min_filter_const
lemma is_max_on_const {b : β} : is_max_on (λ _, b) s a := is_max_filter_const
lemma is_extr_on_const {b : β} : is_extr_on (λ _, b) s a := is_extr_filter_const
/-! ### Order dual -/
lemma is_min_filter_dual_iff : @is_min_filter α (order_dual β) _ f l a ↔ is_max_filter f l a :=
iff.rfl
lemma is_max_filter_dual_iff : @is_max_filter α (order_dual β) _ f l a ↔ is_min_filter f l a :=
iff.rfl
lemma is_extr_filter_dual_iff : @is_extr_filter α (order_dual β) _ f l a ↔ is_extr_filter f l a :=
or_comm _ _
alias is_min_filter_dual_iff ↔ is_min_filter.undual is_max_filter.dual
alias is_max_filter_dual_iff ↔ is_max_filter.undual is_min_filter.dual
alias is_extr_filter_dual_iff ↔ is_extr_filter.undual is_extr_filter.dual
lemma is_min_on_dual_iff : @is_min_on α (order_dual β) _ f s a ↔ is_max_on f s a := iff.rfl
lemma is_max_on_dual_iff : @is_max_on α (order_dual β) _ f s a ↔ is_min_on f s a := iff.rfl
lemma is_extr_on_dual_iff : @is_extr_on α (order_dual β) _ f s a ↔ is_extr_on f s a := or_comm _ _
alias is_min_on_dual_iff ↔ is_min_on.undual is_max_on.dual
alias is_max_on_dual_iff ↔ is_max_on.undual is_min_on.dual
alias is_extr_on_dual_iff ↔ is_extr_on.undual is_extr_on.dual
/-! ### Operations on the filter/set -/
lemma is_min_filter.filter_mono (h : is_min_filter f l a) (hl : l' ≤ l) :
is_min_filter f l' a := hl h
lemma is_max_filter.filter_mono (h : is_max_filter f l a) (hl : l' ≤ l) :
is_max_filter f l' a := hl h
lemma is_extr_filter.filter_mono (h : is_extr_filter f l a) (hl : l' ≤ l) :
is_extr_filter f l' a :=
h.elim (λ h, (h.filter_mono hl).is_extr) (λ h, (h.filter_mono hl).is_extr)
lemma is_min_filter.filter_inf (h : is_min_filter f l a) (l') : is_min_filter f (l ⊓ l') a :=
h.filter_mono inf_le_left
lemma is_max_filter.filter_inf (h : is_max_filter f l a) (l') : is_max_filter f (l ⊓ l') a :=
h.filter_mono inf_le_left
lemma is_extr_filter.filter_inf (h : is_extr_filter f l a) (l') : is_extr_filter f (l ⊓ l') a :=
h.filter_mono inf_le_left
lemma is_min_on.on_subset (hf : is_min_on f t a) (h : s ⊆ t) : is_min_on f s a :=
hf.filter_mono $ principal_mono.2 h
lemma is_max_on.on_subset (hf : is_max_on f t a) (h : s ⊆ t) : is_max_on f s a :=
hf.filter_mono $ principal_mono.2 h
lemma is_extr_on.on_subset (hf : is_extr_on f t a) (h : s ⊆ t) : is_extr_on f s a :=
hf.filter_mono $ principal_mono.2 h
lemma is_min_on.inter (hf : is_min_on f s a) (t) : is_min_on f (s ∩ t) a :=
hf.on_subset (inter_subset_left s t)
lemma is_max_on.inter (hf : is_max_on f s a) (t) : is_max_on f (s ∩ t) a :=
hf.on_subset (inter_subset_left s t)
lemma is_extr_on.inter (hf : is_extr_on f s a) (t) : is_extr_on f (s ∩ t) a :=
hf.on_subset (inter_subset_left s t)
/-! ### Composition with (anti)monotone functions -/
lemma is_min_filter.comp_mono (hf : is_min_filter f l a) {g : β → γ} (hg : monotone g) :
is_min_filter (g ∘ f) l a :=
mem_of_superset hf $ λ x hx, hg hx
lemma is_max_filter.comp_mono (hf : is_max_filter f l a) {g : β → γ} (hg : monotone g) :
is_max_filter (g ∘ f) l a :=
mem_of_superset hf $ λ x hx, hg hx
lemma is_extr_filter.comp_mono (hf : is_extr_filter f l a) {g : β → γ} (hg : monotone g) :
is_extr_filter (g ∘ f) l a :=
hf.elim (λ hf, (hf.comp_mono hg).is_extr) (λ hf, (hf.comp_mono hg).is_extr)
lemma is_min_filter.comp_antimono (hf : is_min_filter f l a) {g : β → γ}
(hg : ∀ ⦃x y⦄, x ≤ y → g y ≤ g x) :
is_max_filter (g ∘ f) l a :=
hf.dual.comp_mono (λ x y h, hg h)
lemma is_max_filter.comp_antimono (hf : is_max_filter f l a) {g : β → γ}
(hg : ∀ ⦃x y⦄, x ≤ y → g y ≤ g x) :
is_min_filter (g ∘ f) l a :=
hf.dual.comp_mono (λ x y h, hg h)
lemma is_extr_filter.comp_antimono (hf : is_extr_filter f l a) {g : β → γ}
(hg : ∀ ⦃x y⦄, x ≤ y → g y ≤ g x) :
is_extr_filter (g ∘ f) l a :=
hf.dual.comp_mono (λ x y h, hg h)
lemma is_min_on.comp_mono (hf : is_min_on f s a) {g : β → γ} (hg : monotone g) :
is_min_on (g ∘ f) s a :=
hf.comp_mono hg
lemma is_max_on.comp_mono (hf : is_max_on f s a) {g : β → γ} (hg : monotone g) :
is_max_on (g ∘ f) s a :=
hf.comp_mono hg
lemma is_extr_on.comp_mono (hf : is_extr_on f s a) {g : β → γ} (hg : monotone g) :
is_extr_on (g ∘ f) s a :=
hf.comp_mono hg
lemma is_min_on.comp_antimono (hf : is_min_on f s a) {g : β → γ}
(hg : ∀ ⦃x y⦄, x ≤ y → g y ≤ g x) :
is_max_on (g ∘ f) s a :=
hf.comp_antimono hg
lemma is_max_on.comp_antimono (hf : is_max_on f s a) {g : β → γ}
(hg : ∀ ⦃x y⦄, x ≤ y → g y ≤ g x) :
is_min_on (g ∘ f) s a :=
hf.comp_antimono hg
lemma is_extr_on.comp_antimono (hf : is_extr_on f s a) {g : β → γ}
(hg : ∀ ⦃x y⦄, x ≤ y → g y ≤ g x) :
is_extr_on (g ∘ f) s a :=
hf.comp_antimono hg
lemma is_min_filter.bicomp_mono [preorder δ] {op : β → γ → δ} (hop : ((≤) ⇒ (≤) ⇒ (≤)) op op)
(hf : is_min_filter f l a) {g : α → γ} (hg : is_min_filter g l a) :
is_min_filter (λ x, op (f x) (g x)) l a :=
mem_of_superset (inter_mem hf hg) $ λ x ⟨hfx, hgx⟩, hop hfx hgx
lemma is_max_filter.bicomp_mono [preorder δ] {op : β → γ → δ} (hop : ((≤) ⇒ (≤) ⇒ (≤)) op op)
(hf : is_max_filter f l a) {g : α → γ} (hg : is_max_filter g l a) :
is_max_filter (λ x, op (f x) (g x)) l a :=
mem_of_superset (inter_mem hf hg) $ λ x ⟨hfx, hgx⟩, hop hfx hgx
-- No `extr` version because we need `hf` and `hg` to be of the same kind
lemma is_min_on.bicomp_mono [preorder δ] {op : β → γ → δ} (hop : ((≤) ⇒ (≤) ⇒ (≤)) op op)
(hf : is_min_on f s a) {g : α → γ} (hg : is_min_on g s a) :
is_min_on (λ x, op (f x) (g x)) s a :=
hf.bicomp_mono hop hg
lemma is_max_on.bicomp_mono [preorder δ] {op : β → γ → δ} (hop : ((≤) ⇒ (≤) ⇒ (≤)) op op)
(hf : is_max_on f s a) {g : α → γ} (hg : is_max_on g s a) :
is_max_on (λ x, op (f x) (g x)) s a :=
hf.bicomp_mono hop hg
/-! ### Composition with `tendsto` -/
lemma is_min_filter.comp_tendsto {g : δ → α} {l' : filter δ} {b : δ} (hf : is_min_filter f l (g b))
(hg : tendsto g l' l) :
is_min_filter (f ∘ g) l' b :=
hg hf
lemma is_max_filter.comp_tendsto {g : δ → α} {l' : filter δ} {b : δ} (hf : is_max_filter f l (g b))
(hg : tendsto g l' l) :
is_max_filter (f ∘ g) l' b :=
hg hf
lemma is_extr_filter.comp_tendsto {g : δ → α} {l' : filter δ} {b : δ}
(hf : is_extr_filter f l (g b)) (hg : tendsto g l' l) :
is_extr_filter (f ∘ g) l' b :=
hf.elim (λ hf, (hf.comp_tendsto hg).is_extr) (λ hf, (hf.comp_tendsto hg).is_extr)
lemma is_min_on.on_preimage (g : δ → α) {b : δ} (hf : is_min_on f s (g b)) :
is_min_on (f ∘ g) (g ⁻¹' s) b :=
hf.comp_tendsto (tendsto_principal_principal.mpr $ subset.refl _)
lemma is_max_on.on_preimage (g : δ → α) {b : δ} (hf : is_max_on f s (g b)) :
is_max_on (f ∘ g) (g ⁻¹' s) b :=
hf.comp_tendsto (tendsto_principal_principal.mpr $ subset.refl _)
lemma is_extr_on.on_preimage (g : δ → α) {b : δ} (hf : is_extr_on f s (g b)) :
is_extr_on (f ∘ g) (g ⁻¹' s) b :=
hf.elim (λ hf, (hf.on_preimage g).is_extr) (λ hf, (hf.on_preimage g).is_extr)
end preorder
/-! ### Pointwise addition -/
section ordered_add_comm_monoid
variables [ordered_add_comm_monoid β] {f g : α → β} {a : α} {s : set α} {l : filter α}
lemma is_min_filter.add (hf : is_min_filter f l a) (hg : is_min_filter g l a) :
is_min_filter (λ x, f x + g x) l a :=
show is_min_filter (λ x, f x + g x) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, add_le_add hx hy) hg
lemma is_max_filter.add (hf : is_max_filter f l a) (hg : is_max_filter g l a) :
is_max_filter (λ x, f x + g x) l a :=
show is_max_filter (λ x, f x + g x) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, add_le_add hx hy) hg
lemma is_min_on.add (hf : is_min_on f s a) (hg : is_min_on g s a) :
is_min_on (λ x, f x + g x) s a :=
hf.add hg
lemma is_max_on.add (hf : is_max_on f s a) (hg : is_max_on g s a) :
is_max_on (λ x, f x + g x) s a :=
hf.add hg
end ordered_add_comm_monoid
/-! ### Pointwise negation and subtraction -/
section ordered_add_comm_group
variables [ordered_add_comm_group β] {f g : α → β} {a : α} {s : set α} {l : filter α}
lemma is_min_filter.neg (hf : is_min_filter f l a) : is_max_filter (λ x, -f x) l a :=
hf.comp_antimono (λ x y hx, neg_le_neg hx)
lemma is_max_filter.neg (hf : is_max_filter f l a) : is_min_filter (λ x, -f x) l a :=
hf.comp_antimono (λ x y hx, neg_le_neg hx)
lemma is_extr_filter.neg (hf : is_extr_filter f l a) : is_extr_filter (λ x, -f x) l a :=
hf.elim (λ hf, hf.neg.is_extr) (λ hf, hf.neg.is_extr)
lemma is_min_on.neg (hf : is_min_on f s a) : is_max_on (λ x, -f x) s a :=
hf.comp_antimono (λ x y hx, neg_le_neg hx)
lemma is_max_on.neg (hf : is_max_on f s a) : is_min_on (λ x, -f x) s a :=
hf.comp_antimono (λ x y hx, neg_le_neg hx)
lemma is_extr_on.neg (hf : is_extr_on f s a) : is_extr_on (λ x, -f x) s a :=
hf.elim (λ hf, hf.neg.is_extr) (λ hf, hf.neg.is_extr)
lemma is_min_filter.sub (hf : is_min_filter f l a) (hg : is_max_filter g l a) :
is_min_filter (λ x, f x - g x) l a :=
by simpa only [sub_eq_add_neg] using hf.add hg.neg
lemma is_max_filter.sub (hf : is_max_filter f l a) (hg : is_min_filter g l a) :
is_max_filter (λ x, f x - g x) l a :=
by simpa only [sub_eq_add_neg] using hf.add hg.neg
lemma is_min_on.sub (hf : is_min_on f s a) (hg : is_max_on g s a) :
is_min_on (λ x, f x - g x) s a :=
by simpa only [sub_eq_add_neg] using hf.add hg.neg
lemma is_max_on.sub (hf : is_max_on f s a) (hg : is_min_on g s a) :
is_max_on (λ x, f x - g x) s a :=
by simpa only [sub_eq_add_neg] using hf.add hg.neg
end ordered_add_comm_group
/-! ### Pointwise `sup`/`inf` -/
section semilattice_sup
variables [semilattice_sup β] {f g : α → β} {a : α} {s : set α} {l : filter α}
lemma is_min_filter.sup (hf : is_min_filter f l a) (hg : is_min_filter g l a) :
is_min_filter (λ x, f x ⊔ g x) l a :=
show is_min_filter (λ x, f x ⊔ g x) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, sup_le_sup hx hy) hg
lemma is_max_filter.sup (hf : is_max_filter f l a) (hg : is_max_filter g l a) :
is_max_filter (λ x, f x ⊔ g x) l a :=
show is_max_filter (λ x, f x ⊔ g x) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, sup_le_sup hx hy) hg
lemma is_min_on.sup (hf : is_min_on f s a) (hg : is_min_on g s a) :
is_min_on (λ x, f x ⊔ g x) s a :=
hf.sup hg
lemma is_max_on.sup (hf : is_max_on f s a) (hg : is_max_on g s a) :
is_max_on (λ x, f x ⊔ g x) s a :=
hf.sup hg
end semilattice_sup
section semilattice_inf
variables [semilattice_inf β] {f g : α → β} {a : α} {s : set α} {l : filter α}
lemma is_min_filter.inf (hf : is_min_filter f l a) (hg : is_min_filter g l a) :
is_min_filter (λ x, f x ⊓ g x) l a :=
show is_min_filter (λ x, f x ⊓ g x) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, inf_le_inf hx hy) hg
lemma is_max_filter.inf (hf : is_max_filter f l a) (hg : is_max_filter g l a) :
is_max_filter (λ x, f x ⊓ g x) l a :=
show is_max_filter (λ x, f x ⊓ g x) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, inf_le_inf hx hy) hg
lemma is_min_on.inf (hf : is_min_on f s a) (hg : is_min_on g s a) :
is_min_on (λ x, f x ⊓ g x) s a :=
hf.inf hg
lemma is_max_on.inf (hf : is_max_on f s a) (hg : is_max_on g s a) :
is_max_on (λ x, f x ⊓ g x) s a :=
hf.inf hg
end semilattice_inf
/-! ### Pointwise `min`/`max` -/
section linear_order
variables [linear_order β] {f g : α → β} {a : α} {s : set α} {l : filter α}
lemma is_min_filter.min (hf : is_min_filter f l a) (hg : is_min_filter g l a) :
is_min_filter (λ x, min (f x) (g x)) l a :=
show is_min_filter (λ x, min (f x) (g x)) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, min_le_min hx hy) hg
lemma is_max_filter.min (hf : is_max_filter f l a) (hg : is_max_filter g l a) :
is_max_filter (λ x, min (f x) (g x)) l a :=
show is_max_filter (λ x, min (f x) (g x)) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, min_le_min hx hy) hg
lemma is_min_on.min (hf : is_min_on f s a) (hg : is_min_on g s a) :
is_min_on (λ x, min (f x) (g x)) s a :=
hf.min hg
lemma is_max_on.min (hf : is_max_on f s a) (hg : is_max_on g s a) :
is_max_on (λ x, min (f x) (g x)) s a :=
hf.min hg
lemma is_min_filter.max (hf : is_min_filter f l a) (hg : is_min_filter g l a) :
is_min_filter (λ x, max (f x) (g x)) l a :=
show is_min_filter (λ x, max (f x) (g x)) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, max_le_max hx hy) hg
lemma is_max_filter.max (hf : is_max_filter f l a) (hg : is_max_filter g l a) :
is_max_filter (λ x, max (f x) (g x)) l a :=
show is_max_filter (λ x, max (f x) (g x)) l a,
from hf.bicomp_mono (λ x x' hx y y' hy, max_le_max hx hy) hg
lemma is_min_on.max (hf : is_min_on f s a) (hg : is_min_on g s a) :
is_min_on (λ x, max (f x) (g x)) s a :=
hf.max hg
lemma is_max_on.max (hf : is_max_on f s a) (hg : is_max_on g s a) :
is_max_on (λ x, max (f x) (g x)) s a :=
hf.max hg
end linear_order
section eventually
/-! ### Relation with `eventually` comparisons of two functions -/
lemma filter.eventually_le.is_max_filter {α β : Type*} [preorder β] {f g : α → β} {a : α}
{l : filter α} (hle : g ≤ᶠ[l] f) (hfga : f a = g a) (h : is_max_filter f l a) :
is_max_filter g l a :=
begin
refine hle.mp (h.mono $ λ x hf hgf, _),
rw ← hfga,
exact le_trans hgf hf
end
lemma is_max_filter.congr {α β : Type*} [preorder β] {f g : α → β} {a : α} {l : filter α}
(h : is_max_filter f l a) (heq : f =ᶠ[l] g) (hfga : f a = g a) :
is_max_filter g l a :=
heq.symm.le.is_max_filter hfga h
lemma filter.eventually_eq.is_max_filter_iff {α β : Type*} [preorder β] {f g : α → β} {a : α}
{l : filter α} (heq : f =ᶠ[l] g) (hfga : f a = g a) :
is_max_filter f l a ↔ is_max_filter g l a :=
⟨λ h, h.congr heq hfga, λ h, h.congr heq.symm hfga.symm⟩
lemma filter.eventually_le.is_min_filter {α β : Type*} [preorder β] {f g : α → β} {a : α}
{l : filter α} (hle : f ≤ᶠ[l] g) (hfga : f a = g a) (h : is_min_filter f l a) :
is_min_filter g l a :=
@filter.eventually_le.is_max_filter _ (order_dual β) _ _ _ _ _ hle hfga h
lemma is_min_filter.congr {α β : Type*} [preorder β] {f g : α → β} {a : α} {l : filter α}
(h : is_min_filter f l a) (heq : f =ᶠ[l] g) (hfga : f a = g a) :
is_min_filter g l a :=
heq.le.is_min_filter hfga h
lemma filter.eventually_eq.is_min_filter_iff {α β : Type*} [preorder β] {f g : α → β} {a : α}
{l : filter α} (heq : f =ᶠ[l] g) (hfga : f a = g a) :
is_min_filter f l a ↔ is_min_filter g l a :=
⟨λ h, h.congr heq hfga, λ h, h.congr heq.symm hfga.symm⟩
lemma is_extr_filter.congr {α β : Type*} [preorder β] {f g : α → β} {a : α} {l : filter α}
(h : is_extr_filter f l a) (heq : f =ᶠ[l] g) (hfga : f a = g a) :
is_extr_filter g l a :=
begin
rw is_extr_filter at *,
rwa [← heq.is_max_filter_iff hfga, ← heq.is_min_filter_iff hfga],
end
lemma filter.eventually_eq.is_extr_filter_iff {α β : Type*} [preorder β] {f g : α → β} {a : α}
{l : filter α} (heq : f =ᶠ[l] g) (hfga : f a = g a) :
is_extr_filter f l a ↔ is_extr_filter g l a :=
⟨λ h, h.congr heq hfga, λ h, h.congr heq.symm hfga.symm⟩
end eventually
|
881985a568697949a17b1e4551247a9a75648115 | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /test/unfold_cases.lean | 0c258e189b88ef8217a1ffa7650d4eabb3f8549c | [
"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 | 3,052 | lean | /-
Copyright (c) 2020 Dany Fabian. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Dany Fabian
-/
import tactic.unfold_cases
open tactic
variable {α : Type*}
inductive color
| red
| black
inductive node (α)
| leaf {} : node
| tree {} (color : color) (left : node) (val : α) (right : node) : node
/-- this function creates 122 cases as opposed to the 5 we see here. -/
def balance_eqn_compiler {α} : color → node α → α → node α → node α
| color.black (node.tree color.red (node.tree color.red a x b) y c) z d :=
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d)
| color.black (node.tree color.red a x (node.tree color.red b y c)) z d :=
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d)
| color.black a x (node.tree color.red (node.tree color.red b y c) z d) :=
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d)
| color.black a x (node.tree color.red b y (node.tree color.red c z d)) :=
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d)
| color a x b := node.tree color a x b
example : ∀ a (x:α) b y c z d, balance_eqn_compiler color.black (node.tree color.red (node.tree color.red a x b) y c) z d =
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d) :=
begin
unfold_cases { refl },
end
/-- this function creates 122 cases as opposed to the 5 we see here. -/
def balance_match {α} (c:color) (l:node α) (v:α) (r:node α) : node α :=
match c, l, v, r with
| color.black, node.tree color.red (node.tree color.red a x b) y c, z, d :=
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d)
| color.black, node.tree color.red a x (node.tree color.red b y c), z, d :=
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d)
| color.black, a, x, node.tree color.red (node.tree color.red b y c) z d :=
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d)
| color.black, a, x, node.tree color.red b y (node.tree color.red c z d) :=
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d)
| color, a, x, b := node.tree color a x b
end
example : ∀ a (x:α) b y c z d, balance_match color.black (node.tree color.red (node.tree color.red a x b) y c) z d =
node.tree color.red (node.tree color.black a x b) y (node.tree color.black c z d) :=
begin
unfold_cases { refl },
end
def foo : ℕ → ℕ → ℕ
| 0 0 := 17
| (n+2) 17 := 17
| 1 0 := 23
| 0 (n+18) := 15
| 0 17 := 17
| 1 17 := 17
| _ (n+18) := 27
| _ _ := 15
example : ∀ x, foo x 17 = 17 :=
begin
unfold_cases { refl },
end
def bar : ℕ → ℕ
| 17 := 17
| 9 := 17
| n := 17
example : ∀ x, bar x = 17 :=
begin
unfold_cases { refl }
end
def baz : ℕ → ℕ → Prop
| 0 0 := false
| 0 n := true
| n 0 := false
| n m := n < m
example : ∀ x, baz x 0 = false :=
begin
unfold_cases { refl },
end
|
b961067a7e256b83f7834dd7507095bb3b3d0360 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/topology/algebra/continuous_monoid_hom.lean | d35b9e98677b798630e962d5603b3cfe1f21a245 | [
"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 | 11,740 | 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 analysis.complex.circle
import topology.continuous_function.algebra
/-!
# Continuous Monoid Homs
This file defines the space of continuous homomorphisms between two topological groups.
## Main definitions
* `continuous_monoid_hom A B`: The continuous homomorphisms `A →* B`.
* `continuous_add_monoid_hom α β`: The continuous additive homomorphisms `α →+ β`.
-/
open_locale pointwise
open function
variables {F α β : Type*} (A B C D E : Type*)
[monoid A] [monoid B] [monoid C] [monoid D] [comm_group E]
[topological_space A] [topological_space B] [topological_space C] [topological_space D]
[topological_space E] [topological_group E]
/-- The type of continuous additive monoid homomorphisms from `α` to `β`.
When possible, instead of parametrizing results over `(f : continuous_add_monoid_hom α β)`,
you should parametrize over `(F : Type*) [continuous_add_monoid_hom_class F α β] (f : F)`.
When you extend this structure, make sure to extend `continuous_add_monoid_hom_class`. -/
structure continuous_add_monoid_hom (A B : Type*) [add_monoid A] [add_monoid B]
[topological_space A] [topological_space B] extends A →+ B :=
(continuous_to_fun : continuous to_fun)
/-- The type of continuous monoid homomorphisms from `α` to `β`.
When possible, instead of parametrizing results over `(f : continuous_monoid_hom α β)`,
you should parametrize over `(F : Type*) [continuous_monoid_hom_class F α β] (f : F)`.
When you extend this structure, make sure to extend `continuous_add_monoid_hom_class`. -/
@[to_additive]
structure continuous_monoid_hom extends A →* B :=
(continuous_to_fun : continuous to_fun)
/-- `continuous_add_monoid_hom_class F α β` states that `F` is a type of continuous additive monoid
homomorphisms.
You should also extend this typeclass when you extend `continuous_add_monoid_hom`. -/
class continuous_add_monoid_hom_class (F α β : Type*) [add_monoid α] [add_monoid β]
[topological_space α] [topological_space β] extends add_monoid_hom_class F α β :=
(map_continuous (f : F) : continuous f)
/-- `continuous_monoid_hom_class F α β` states that `F` is a type of continuous additive monoid
homomorphisms.
You should also extend this typeclass when you extend `continuous_monoid_hom`. -/
@[to_additive]
class continuous_monoid_hom_class (F α β : Type*) [monoid α] [monoid β]
[topological_space α] [topological_space β] extends monoid_hom_class F α β :=
(map_continuous (f : F) : continuous f)
/-- Reinterpret a `continuous_monoid_hom` as a `monoid_hom`. -/
add_decl_doc continuous_monoid_hom.to_monoid_hom
/-- Reinterpret a `continuous_add_monoid_hom` as an `add_monoid_hom`. -/
add_decl_doc continuous_add_monoid_hom.to_add_monoid_hom
@[priority 100, to_additive] -- See note [lower instance priority]
instance continuous_monoid_hom_class.to_continuous_map_class [monoid α] [monoid β]
[topological_space α] [topological_space β] [continuous_monoid_hom_class F α β] :
continuous_map_class F α β :=
{ .. ‹continuous_monoid_hom_class F α β› }
namespace continuous_monoid_hom
variables {A B C D E} [monoid α] [monoid β] [topological_space α] [topological_space β]
@[to_additive]
instance : continuous_monoid_hom_class (continuous_monoid_hom α β) α β :=
{ coe := λ f, f.to_fun,
coe_injective' := λ f g h, by { obtain ⟨⟨_, _⟩, _⟩ := f, obtain ⟨⟨_, _⟩, _⟩ := g, congr' },
map_mul := λ f, f.map_mul',
map_one := λ f, f.map_one',
map_continuous := λ f, f.continuous_to_fun }
/-- Helper instance for when there's too many metavariables to apply `fun_like.has_coe_to_fun`
directly. -/
@[to_additive] instance : has_coe_to_fun (continuous_monoid_hom A B) (λ _, A → B) :=
fun_like.has_coe_to_fun
@[to_additive] lemma ext {f g : continuous_monoid_hom A B} (h : ∀ x, f x = g x) : f = g :=
fun_like.ext _ _ h
/-- Reinterpret a `continuous_monoid_hom` as a `continuous_map`. -/
@[to_additive "Reinterpret a `continuous_add_monoid_hom` as a `continuous_map`."]
def to_continuous_map (f : continuous_monoid_hom α β) : C(α, β) := { .. f}
@[to_additive] lemma to_continuous_map_injective : injective (to_continuous_map : _ → C(α, β)) :=
λ f g h, ext $ by convert fun_like.ext_iff.1 h
/-- Construct a `continuous_monoid_hom` from a `continuous` `monoid_hom`. -/
@[to_additive "Construct a `continuous_add_monoid_hom` from a `continuous` `add_monoid_hom`.",
simps]
def mk' (f : A →* B) (hf : continuous f) : continuous_monoid_hom A B :=
{ continuous_to_fun := hf, .. f }
/-- Composition of two continuous homomorphisms. -/
@[to_additive "Composition of two continuous homomorphisms.", simps]
def comp (g : continuous_monoid_hom B C) (f : continuous_monoid_hom A B) :
continuous_monoid_hom A C :=
mk' (g.to_monoid_hom.comp f.to_monoid_hom) (g.continuous_to_fun.comp f.continuous_to_fun)
/-- Product of two continuous homomorphisms on the same space. -/
@[to_additive "Product of two continuous homomorphisms on the same space.", simps]
def prod (f : continuous_monoid_hom A B) (g : continuous_monoid_hom A C) :
continuous_monoid_hom A (B × C) :=
mk' (f.to_monoid_hom.prod g.to_monoid_hom) (f.continuous_to_fun.prod_mk g.continuous_to_fun)
/-- Product of two continuous homomorphisms on different spaces. -/
@[to_additive "Product of two continuous homomorphisms on different spaces.", simps]
def prod_map (f : continuous_monoid_hom A C) (g : continuous_monoid_hom B D) :
continuous_monoid_hom (A × B) (C × D) :=
mk' (f.to_monoid_hom.prod_map g.to_monoid_hom) (f.continuous_to_fun.prod_map g.continuous_to_fun)
variables (A B C D E)
/-- The trivial continuous homomorphism. -/
@[to_additive "The trivial continuous homomorphism.", simps]
def one : continuous_monoid_hom A B := mk' 1 continuous_const
@[to_additive] instance : inhabited (continuous_monoid_hom A B) := ⟨one A B⟩
/-- The identity continuous homomorphism. -/
@[to_additive "The identity continuous homomorphism.", simps]
def id : continuous_monoid_hom A A := mk' (monoid_hom.id A) continuous_id
/-- The continuous homomorphism given by projection onto the first factor. -/
@[to_additive "The continuous homomorphism given by projection onto the first factor.", simps]
def fst : continuous_monoid_hom (A × B) A := mk' (monoid_hom.fst A B) continuous_fst
/-- The continuous homomorphism given by projection onto the second factor. -/
@[to_additive "The continuous homomorphism given by projection onto the second factor.", simps]
def snd : continuous_monoid_hom (A × B) B := mk' (monoid_hom.snd A B) continuous_snd
/-- The continuous homomorphism given by inclusion of the first factor. -/
@[to_additive "The continuous homomorphism given by inclusion of the first factor.", simps]
def inl : continuous_monoid_hom A (A × B) := prod (id A) (one A B)
/-- The continuous homomorphism given by inclusion of the second factor. -/
@[to_additive "The continuous homomorphism given by inclusion of the second factor.", simps]
def inr : continuous_monoid_hom B (A × B) := prod (one B A) (id B)
/-- The continuous homomorphism given by the diagonal embedding. -/
@[to_additive "The continuous homomorphism given by the diagonal embedding.", simps]
def diag : continuous_monoid_hom A (A × A) := prod (id A) (id A)
/-- The continuous homomorphism given by swapping components. -/
@[to_additive "The continuous homomorphism given by swapping components.", simps]
def swap : continuous_monoid_hom (A × B) (B × A) := prod (snd A B) (fst A B)
/-- The continuous homomorphism given by multiplication. -/
@[to_additive "The continuous homomorphism given by addition.", simps]
def mul : continuous_monoid_hom (E × E) E :=
mk' mul_monoid_hom continuous_mul
/-- The continuous homomorphism given by inversion. -/
@[to_additive "The continuous homomorphism given by negation.", simps]
def inv : continuous_monoid_hom E E :=
mk' comm_group.inv_monoid_hom continuous_inv
variables {A B C D E}
/-- Coproduct of two continuous homomorphisms to the same space. -/
@[to_additive "Coproduct of two continuous homomorphisms to the same space.", simps]
def coprod (f : continuous_monoid_hom A E) (g : continuous_monoid_hom B E) :
continuous_monoid_hom (A × B) E :=
(mul E).comp (f.prod_map g)
@[to_additive] instance : comm_group (continuous_monoid_hom A E) :=
{ mul := λ f g, (mul E).comp (f.prod g),
mul_comm := λ f g, ext (λ x, mul_comm (f x) (g x)),
mul_assoc := λ f g h, ext (λ x, mul_assoc (f x) (g x) (h x)),
one := one A E,
one_mul := λ f, ext (λ x, one_mul (f x)),
mul_one := λ f, ext (λ x, mul_one (f x)),
inv := λ f, (inv E).comp f,
mul_left_inv := λ f, ext (λ x, mul_left_inv (f x)) }
instance : topological_space (continuous_monoid_hom A B) :=
topological_space.induced to_continuous_map continuous_map.compact_open
variables (A B C D E)
lemma is_inducing : inducing (to_continuous_map : continuous_monoid_hom A B → C(A, B)) := ⟨rfl⟩
lemma is_embedding : embedding (to_continuous_map : continuous_monoid_hom A B → C(A, B)) :=
⟨is_inducing A B, to_continuous_map_injective⟩
lemma is_closed_embedding [has_continuous_mul B] [t2_space B] :
closed_embedding (to_continuous_map : continuous_monoid_hom A B → C(A, B)) :=
⟨is_embedding A B, ⟨begin
suffices : (set.range (to_continuous_map : continuous_monoid_hom A B → C(A, B))) =
({f | f '' {1} ⊆ {1}ᶜ} ∪ ⋃ (x y) (U V W) (hU : is_open U) (hV : is_open V) (hW : is_open W)
(h : disjoint (U * V) W), {f | f '' {x} ⊆ U} ∩ {f | f '' {y} ⊆ V} ∩ {f | f '' {x * y} ⊆ W})ᶜ,
{ rw [this, compl_compl],
refine (continuous_map.is_open_gen is_compact_singleton is_open_compl_singleton).union _,
repeat { apply is_open_Union, intro, },
repeat { apply is_open.inter },
all_goals { apply continuous_map.is_open_gen is_compact_singleton, assumption } },
simp_rw [set.compl_union, set.compl_Union, set.image_singleton, set.singleton_subset_iff,
set.ext_iff, set.mem_inter_iff, set.mem_Inter, set.mem_compl_iff],
refine λ f, ⟨_, _⟩,
{ rintros ⟨f, rfl⟩,
exact ⟨λ h, h (map_one f), λ x y U V W hU hV hW h ⟨⟨hfU, hfV⟩, hfW⟩,
h ⟨set.mul_mem_mul hfU hfV, (congr_arg (∈ W) (map_mul f x y)).mp hfW⟩⟩ },
{ rintros ⟨hf1, hf2⟩,
suffices : ∀ x y, f (x * y) = f x * f y,
{ refine ⟨({ map_one' := of_not_not hf1, map_mul' := this, .. f } : continuous_monoid_hom A B),
continuous_map.ext (λ _, rfl)⟩, },
intros x y,
contrapose! hf2,
obtain ⟨UV, W, hUV, hW, hfUV, hfW, h⟩ := t2_separation hf2.symm,
have hB := @continuous_mul B _ _ _,
obtain ⟨U, V, hU, hV, hfU, hfV, h'⟩ := is_open_prod_iff.mp (hUV.preimage hB) (f x) (f y) hfUV,
refine ⟨x, y, U, V, W, hU, hV, hW, ((disjoint_iff.mpr h).mono_left _), ⟨hfU, hfV⟩, hfW⟩,
rintros _ ⟨x, y, hx : (x, y).1 ∈ U, hy : (x, y).2 ∈ V, rfl⟩,
exact h' ⟨hx, hy⟩ },
end⟩⟩
variables {A B C D E}
instance [t2_space B] : t2_space (continuous_monoid_hom A B) :=
(is_embedding A B).t2_space
instance : topological_group (continuous_monoid_hom A E) :=
let hi := is_inducing A E, hc := hi.continuous in
{ continuous_mul := hi.continuous_iff.mpr (continuous_mul.comp (continuous.prod_map hc hc)),
continuous_inv := hi.continuous_iff.mpr (continuous_inv.comp hc) }
end continuous_monoid_hom
/-- The Pontryagin dual of `G` is the group of continuous homomorphism `G → circle`. -/
@[derive [topological_space, t2_space, comm_group, topological_group, inhabited]]
def pontryagin_dual (G : Type*) [monoid G] [topological_space G] := continuous_monoid_hom G circle
|
2dbb896f099db761296f5f1c90bc27a43357df72 | c3f2fcd060adfa2ca29f924839d2d925e8f2c685 | /hott/algebra/precategory/functor.hlean | 147698ccb5c3abba739274be116c9874d5a29b18 | [
"Apache-2.0"
] | permissive | respu/lean | 6582d19a2f2838a28ecd2b3c6f81c32d07b5341d | 8c76419c60b63d0d9f7bc04ebb0b99812d0ec654 | refs/heads/master | 1,610,882,451,231 | 1,427,747,084,000 | 1,427,747,429,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 10,494 | hlean | /-
Copyright (c) 2015 Floris van Doorn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Module: algebra.precategory.functor
Authors: Floris van Doorn, Jakob von Raumer
-/
import .basic types.pi .iso
open function category eq prod equiv is_equiv sigma sigma.ops is_trunc funext iso
open pi
structure functor (C D : Precategory) : Type :=
(to_fun_ob : C → D)
(to_fun_hom : Π ⦃a b : C⦄, hom a b → hom (to_fun_ob a) (to_fun_ob b))
(respect_id : Π (a : C), to_fun_hom (ID a) = ID (to_fun_ob a))
(respect_comp : Π {a b c : C} (g : hom b c) (f : hom a b),
to_fun_hom (g ∘ f) = to_fun_hom g ∘ to_fun_hom f)
namespace functor
infixl `⇒`:25 := functor
variables {A B C D E : Precategory}
attribute to_fun_ob [coercion]
attribute to_fun_hom [coercion]
-- The following lemmas will later be used to prove that the type of
-- precategories forms a precategory itself
protected definition compose [reducible] (G : functor D E) (F : functor C D) : functor C E :=
functor.mk
(λ x, G (F x))
(λ a b f, G (F f))
(λ a, calc
G (F (ID a)) = G (ID (F a)) : by rewrite respect_id
... = ID (G (F a)) : by rewrite respect_id)
(λ a b c g f, calc
G (F (g ∘ f)) = G (F g ∘ F f) : by rewrite respect_comp
... = G (F g) ∘ G (F f) : by rewrite respect_comp)
infixr `∘f`:60 := compose
protected definition id [reducible] {C : Precategory} : functor C C :=
mk (λa, a) (λ a b f, f) (λ a, idp) (λ a b c f g, idp)
protected definition ID [reducible] (C : Precategory) : functor C C := id
definition functor_mk_eq' {F₁ F₂ : C → D} {H₁ : Π(a b : C), hom a b → hom (F₁ a) (F₁ b)}
{H₂ : Π(a b : C), hom a b → hom (F₂ a) (F₂ b)} (id₁ id₂ comp₁ comp₂)
(pF : F₁ = F₂) (pH : pF ▹ H₁ = H₂)
: functor.mk F₁ H₁ id₁ comp₁ = functor.mk F₂ H₂ id₂ comp₂ :=
apD01111 functor.mk pF pH !is_hprop.elim !is_hprop.elim
definition functor_eq' {F₁ F₂ : C ⇒ D}
: Π(p : to_fun_ob F₁ = to_fun_ob F₂),
(transport (λx, Πa b f, hom (x a) (x b)) p (to_fun_hom F₁) = to_fun_hom F₂) → F₁ = F₂ :=
functor.rec_on F₁ (λO₁ H₁ id₁ comp₁, functor.rec_on F₂ (λO₂ H₂ id₂ comp₂ p, !functor_mk_eq'))
definition functor_mk_eq {F₁ F₂ : C → D} {H₁ : Π(a b : C), hom a b → hom (F₁ a) (F₁ b)}
{H₂ : Π(a b : C), hom a b → hom (F₂ a) (F₂ b)} (id₁ id₂ comp₁ comp₂) (pF : F₁ ∼ F₂)
(pH : Π(a b : C) (f : hom a b), hom_of_eq (pF b) ∘ H₁ a b f ∘ inv_of_eq (pF a) = H₂ a b f)
: functor.mk F₁ H₁ id₁ comp₁ = functor.mk F₂ H₂ id₂ comp₂ :=
functor_mk_eq' id₁ id₂ comp₁ comp₂ (eq_of_homotopy pF)
(eq_of_homotopy (λc, eq_of_homotopy (λc', eq_of_homotopy (λf,
begin
apply concat, rotate_left 1, exact (pH c c' f),
apply concat, rotate_left 1, apply transport_hom,
apply concat, rotate_left 1,
exact (pi_transport_constant (eq_of_homotopy pF) (H₁ c c') f),
apply (apD10' f),
apply concat, rotate_left 1,
exact (pi_transport_constant (eq_of_homotopy pF) (H₁ c) c'),
apply (apD10' c'),
apply concat, rotate_left 1,
exact (pi_transport_constant (eq_of_homotopy pF) H₁ c),
apply idp
end))))
definition functor_eq {F₁ F₂ : C ⇒ D} : Π(p : to_fun_ob F₁ ∼ to_fun_ob F₂),
(Π(a b : C) (f : hom a b), hom_of_eq (p b) ∘ F₁ f ∘ inv_of_eq (p a) = F₂ f) → F₁ = F₂ :=
functor.rec_on F₁ (λO₁ H₁ id₁ comp₁, functor.rec_on F₂ (λO₂ H₂ id₂ comp₂ p, !functor_mk_eq))
definition functor_mk_eq_constant {F : C → D} {H₁ : Π(a b : C), hom a b → hom (F a) (F b)}
{H₂ : Π(a b : C), hom a b → hom (F a) (F b)} (id₁ id₂ comp₁ comp₂)
(pH : Π(a b : C) (f : hom a b), H₁ a b f = H₂ a b f)
: functor.mk F H₁ id₁ comp₁ = functor.mk F H₂ id₂ comp₂ :=
functor_eq (λc, idp) (λa b f, !id_leftright ⬝ !pH)
protected definition preserve_iso (F : C ⇒ D) {a b : C} (f : hom a b) [H : is_iso f] :
is_iso (F f) :=
begin
fapply @is_iso.mk, apply (F (f⁻¹)),
repeat (apply concat ; apply inverse ; apply (respect_comp F) ;
apply concat ; apply (ap (λ x, to_fun_hom F x)) ;
[apply left_inverse | apply right_inverse] ;
apply (respect_id F) ),
end
attribute preserve_iso [instance]
protected definition respect_inv (F : C ⇒ D) {a b : C} (f : hom a b)
[H : is_iso f] [H' : is_iso (F f)] :
F (f⁻¹) = (F f)⁻¹ :=
begin
fapply @left_inverse_eq_right_inverse, apply (F f),
apply concat, apply inverse, apply (respect_comp F),
apply concat, apply (ap (λ x, to_fun_hom F x)),
apply left_inverse, apply respect_id,
apply right_inverse,
end
protected definition assoc (H : C ⇒ D) (G : B ⇒ C) (F : A ⇒ B) :
H ∘f (G ∘f F) = (H ∘f G) ∘f F :=
!functor_mk_eq_constant (λa b f, idp)
protected definition id_left (F : C ⇒ D) : id ∘f F = F :=
functor.rec_on F (λF1 F2 F3 F4, !functor_mk_eq_constant (λa b f, idp))
protected definition id_right (F : C ⇒ D) : F ∘f id = F :=
functor.rec_on F (λF1 F2 F3 F4, !functor_mk_eq_constant (λa b f, idp))
protected definition comp_id_eq_id_comp (F : C ⇒ D) : F ∘f functor.id = functor.id ∘f F :=
!functor.id_right ⬝ !functor.id_left⁻¹
-- "functor C D" is equivalent to a certain sigma type
protected definition sigma_char :
(Σ (to_fun_ob : C → D)
(to_fun_hom : Π ⦃a b : C⦄, hom a b → hom (to_fun_ob a) (to_fun_ob b)),
(Π (a : C), to_fun_hom (ID a) = ID (to_fun_ob a)) ×
(Π {a b c : C} (g : hom b c) (f : hom a b),
to_fun_hom (g ∘ f) = to_fun_hom g ∘ to_fun_hom f)) ≃ (functor C D) :=
begin
fapply equiv.MK,
{intro S, fapply functor.mk,
exact (S.1), exact (S.2.1),
exact (pr₁ S.2.2), exact (pr₂ S.2.2)},
{intro F,
cases F with [d1, d2, d3, d4],
exact ⟨d1, d2, (d3, @d4)⟩},
{intro F,
cases F,
apply idp},
{intro S,
cases S with [d1, S2],
cases S2 with [d2, P1],
cases P1,
apply idp},
end
set_option apply.class_instance false
protected definition is_hset_functor
[HD : is_hset D] : is_hset (functor C D) :=
begin
apply is_trunc_is_equiv_closed, apply equiv.to_is_equiv,
apply sigma_char,
apply is_trunc_sigma, apply is_trunc_pi, intros, exact HD, intro F,
apply is_trunc_sigma, apply is_trunc_pi, intro a,
{apply is_trunc_pi, intro b,
apply is_trunc_pi, intro c, apply !homH},
intro H, apply is_trunc_prod,
{apply is_trunc_pi, intro a,
apply is_trunc_eq, apply is_trunc_succ, apply !homH},
{repeat (apply is_trunc_pi; intros),
apply is_trunc_eq, apply is_trunc_succ, apply !homH},
end
definition functor_mk_eq'_idp (F : C → D) (H : Π(a b : C), hom a b → hom (F a) (F b))
(id comp) : functor_mk_eq' id id comp comp (idpath F) (idpath H) = idp :=
begin
fapply (apD011 (apD01111 functor.mk idp idp)),
apply is_hset.elim,
apply is_hset.elim
end
definition functor_eq'_idp (F : C ⇒ D) : functor_eq' idp idp = (idpath F) :=
by (cases F; apply functor_mk_eq'_idp)
definition functor_eq_eta' {F₁ F₂ : C ⇒ D} (p : F₁ = F₂)
: functor_eq' (ap to_fun_ob p) (!transport_compose⁻¹ ⬝ apD to_fun_hom p) = p :=
begin
cases p, cases F₁,
apply concat, rotate_left 1, apply functor_eq'_idp,
apply (ap (functor_eq' idp)),
apply idp_con,
end
definition functor_eq2' {F₁ F₂ : C ⇒ D} {p₁ p₂ : to_fun_ob F₁ = to_fun_ob F₂} (q₁ q₂)
(r : p₁ = p₂) : functor_eq' p₁ q₁ = functor_eq' p₂ q₂ :=
by cases r; apply (ap (functor_eq' p₂)); apply is_hprop.elim
definition functor_eq2 {F₁ F₂ : C ⇒ D} (p q : F₁ = F₂) (r : ap010 to_fun_ob p ∼ ap010 to_fun_ob q)
: p = q :=
begin
cases F₁ with [ob₁, hom₁, id₁, comp₁],
cases F₂ with [ob₂, hom₂, id₂, comp₂],
rewrite [-functor_eq_eta' p, -functor_eq_eta' q],
apply functor_eq2',
apply ap_eq_ap_of_homotopy,
exact r,
end
-- definition ap010_functor_eq_mk' {F₁ F₂ : C ⇒ D} (p : to_fun_ob F₁ = to_fun_ob F₂)
-- (q : p ▹ F₁ = F₂) (c : C) :
-- ap to_fun_ob (functor_eq_mk (apD10 p) (λa b f, _)) = p := sorry
-- begin
-- cases F₂, revert q, apply (homotopy.rec_on p), clear p, esimp, intros (p, q),
-- cases p, clears (e_1, e_2),
-- end
-- TODO: remove sorry
definition ap010_functor_eq {F₁ F₂ : C ⇒ D} (p : to_fun_ob F₁ ∼ to_fun_ob F₂)
(q : (λ(a b : C) (f : hom a b), hom_of_eq (p b) ∘ F₁ f ∘ inv_of_eq (p a)) ∼3 to_fun_hom F₂) (c : C) :
ap010 to_fun_ob (functor_eq p q) c = p c :=
begin
cases F₂, revert q, apply (homotopy.rec_on p), clear p, esimp, intros [p, q],
apply sorry,
--apply (homotopy3.rec_on q), clear q, intro q,
--cases p, --TODO: report: this fails
end
definition ap010_functor_mk_eq_constant {F : C → D} {H₁ : Π(a b : C), hom a b → hom (F a) (F b)}
{H₂ : Π(a b : C), hom a b → hom (F a) (F b)} {id₁ id₂ comp₁ comp₂}
(pH : Π(a b : C) (f : hom a b), H₁ a b f = H₂ a b f) (c : C) :
ap010 to_fun_ob (functor_mk_eq_constant id₁ id₂ comp₁ comp₂ pH) c = idp :=
!ap010_functor_eq
--do we need this theorem?
definition compose_pentagon (K : D ⇒ E) (H : C ⇒ D) (G : B ⇒ C) (F : A ⇒ B) :
(calc K ∘f H ∘f G ∘f F = (K ∘f H) ∘f G ∘f F : functor.assoc
... = ((K ∘f H) ∘f G) ∘f F : functor.assoc)
=
(calc K ∘f H ∘f G ∘f F = K ∘f (H ∘f G) ∘f F : ap (λx, K ∘f x) !functor.assoc
... = (K ∘f H ∘f G) ∘f F : functor.assoc
... = ((K ∘f H) ∘f G) ∘f F : ap (λx, x ∘f F) !functor.assoc) :=
sorry
-- begin
-- apply functor_eq2,
-- intro a,
-- rewrite +ap010_con,
-- -- rewrite +ap010_ap,
-- -- apply sorry
-- /-to prove this we need a stronger ap010-lemma, something like
-- ap010 (λy, to_fun_ob (f y)) (functor_mk_eq_constant ...) c = idp
-- or something another way of getting ap out of ap010
-- -/
-- --rewrite +ap010_ap,
-- --unfold functor.assoc,
-- --rewrite ap010_functor_mk_eq_constant,
-- end
end functor
|
1998fe07180fb69debc7c06b9c2d2a002fd190e8 | df561f413cfe0a88b1056655515399c546ff32a5 | /4-power-world/l6.lean | 4dfa059e73406c801d596ef0b15911ccacdb9952 | [] | no_license | nicholaspun/natural-number-game-solutions | 31d5158415c6f582694680044c5c6469032c2a06 | 1e2aed86d2e76a3f4a275c6d99e795ad30cf6df0 | refs/heads/main | 1,675,123,625,012 | 1,607,633,548,000 | 1,607,633,548,000 | 318,933,860 | 3 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 298 | lean | lemma mul_pow (a b n : mynat) : (a * b) ^ n = a ^ n * b ^ n :=
begin
induction n with k Pk,
repeat { rw pow_zero },
rw one_mul,
refl,
rw pow_succ a,
rw mul_assoc (a^k) _ _,
rw mul_left_comm,
rw pow_succ b,
rw ← mul_assoc (a^k) _ _,
rw ← Pk,
rw ← mul_left_comm,
exact pow_succ (a * b) k,
end |
1631a3a143dab140b8695049af63fec4ab6266f3 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/field_theory/primitive_element.lean | 7abeba5f481e849a2451c3fc41c1fde7934fc4da | [] | 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 | 3,317 | lean | /-
Copyright (c) 2020 Thomas Browning and Patrick Lutz. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Thomas Browning and Patrick Lutz
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.field_theory.adjoin
import Mathlib.field_theory.separable
import Mathlib.PostPort
universes u_1 u_2
namespace Mathlib
/-!
# Primitive Element Theorem
In this file we prove the primitive element theorem.
## Main results
- `exists_primitive_element`: a finite separable extension `E / F` has a primitive element, i.e.
there is an `α : E` such that `F⟮α⟯ = (⊤ : subalgebra F E)`.
## Implementation notes
In declaration names, `primitive_element` abbreviates `adjoin_simple_eq_top`:
it stands for the statement `F⟮α⟯ = (⊤ : subalgebra F E)`. We did not add an extra
declaration `is_primitive_element F α := F⟮α⟯ = (⊤ : subalgebra F E)` because this
requires more unfolding without much obvious benefit.
## Tags
primitive element, separable field extension, separable extension, intermediate field, adjoin, exists_adjoin_simple_eq_top
-/
namespace field
/-! ### Primitive element theorem for finite fields -/
/-- Primitive element theorem assuming E is finite. -/
theorem exists_primitive_element_of_fintype_top (F : Type u_1) [field F] (E : Type u_2) [field E] [algebra F E] [fintype E] : ∃ (α : E), intermediate_field.adjoin F (intermediate_field.insert.insert ∅ α) = ⊤ := sorry
/-- Primitive element theorem for finite dimensional extension of a finite field. -/
theorem exists_primitive_element_of_fintype_bot (F : Type u_1) [field F] (E : Type u_2) [field E] [algebra F E] [fintype F] [finite_dimensional F E] : ∃ (α : E), intermediate_field.adjoin F (intermediate_field.insert.insert ∅ α) = ⊤ :=
exists_primitive_element_of_fintype_top F E
/-! ### Primitive element theorem for infinite fields -/
theorem primitive_element_inf_aux_exists_c {F : Type u_1} [field F] [infinite F] {E : Type u_2} [field E] (ϕ : F →+* E) (α : E) (β : E) (f : polynomial F) (g : polynomial F) : ∃ (c : F),
∀ (α' : E),
α' ∈ polynomial.roots (polynomial.map ϕ f) →
∀ (β' : E), β' ∈ polynomial.roots (polynomial.map ϕ g) → -(α' - α) / (β' - β) ≠ coe_fn ϕ c := sorry
-- This is the heart of the proof of the primitive element theorem. It shows that if `F` is
-- infinite and `α` and `β` are separable over `F` then `F⟮α, β⟯` is generated by a single element.
theorem primitive_element_inf_aux {F : Type u_1} [field F] [infinite F] {E : Type u_2} [field E] (α : E) (β : E) [algebra F E] (F_sep : is_separable F E) : ∃ (γ : E),
intermediate_field.adjoin F (intermediate_field.insert.insert (intermediate_field.insert.insert ∅ β) α) =
intermediate_field.adjoin F (intermediate_field.insert.insert ∅ γ) := sorry
/-- Primitive element theorem: a finite separable field extension `E` of `F` has a
primitive element, i.e. there is an `α ∈ E` such that `F⟮α⟯ = (⊤ : subalgebra F E)`.-/
theorem exists_primitive_element {F : Type u_1} [field F] {E : Type u_2} [field E] [algebra F E] [finite_dimensional F E] (F_sep : is_separable F E) : ∃ (α : E), intermediate_field.adjoin F (intermediate_field.insert.insert ∅ α) = ⊤ := sorry
|
81a954b380a07eaadb187849996420a274e12329 | b7f22e51856f4989b970961f794f1c435f9b8f78 | /tests/lean/run/blast_cc11.lean | 9242952a914f4df137764cbc489df03fb99ca837 | [
"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 | 849 | lean | import data.list
set_option blast.strategy "cc"
definition t1 (a b : nat) : (a = b) ↔ (b = a) :=
by blast
print t1
definition t2 (a b : nat) : (a = b) = (b = a) :=
by blast
print t2
definition t3 (a b : nat) : (a = b) == (b = a) :=
by blast
print t3
open perm
definition t4 (a b : list nat) : (a ~ b) ↔ (b ~ a) :=
by blast
definition t5 (a b : list nat) : (a ~ b) = (b ~ a) :=
by blast
definition t6 (a b : list nat) : (a ~ b) == (b ~ a) :=
by blast
definition t7 (p : Prop) (a b : nat) : a = b → b ≠ a → p :=
by blast
definition t8 (a b : Prop) : (a ↔ b) → ((b ↔ a) ↔ (a ↔ b)) :=
by blast
definition t9 (a b c : nat) : b = c → (a = b ↔ c = a) :=
by blast
definition t10 (a b c : list nat) : b ~ c → (a ~ b ↔ c ~ a) :=
by blast
definition t11 (a b c : list nat) : b ~ c → ((a ~ b) = (c ~ a)) :=
by blast
|
0e3ccff07c27f164c170947e04f46767cb78c9e1 | 2f8bf12144551bc7d8087a6320990c4621741f3d | /library/init/lean/parser/syntax.lean | 3c30ea752bb4a6c7d7c5f09c5736dd1b39362447 | [
"Apache-2.0"
] | permissive | jesse-michael-han/lean4 | eb63a12960e69823749edceb4f23fd33fa2253ce | fa16920a6a7700cabc567aa629ce4ae2478a2f40 | refs/heads/master | 1,589,935,810,594 | 1,557,177,860,000 | 1,557,177,860,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 8,448 | lean | /-
Copyright (c) 2018 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Sebastian Ullrich
-/
prelude
import init.lean.name init.lean.parser.parsec
namespace Lean
namespace Parser
--TODO(Sebastian): move
structure Substring :=
(start : String.OldIterator)
(stop : String.OldIterator)
structure SourceInfo :=
/- Will be inferred after parsing by `Syntax.updateLeading`. During parsing,
it is not at all clear what the preceding token was, especially with backtracking. -/
(leading : Substring)
(pos : Parsec.Position)
(trailing : Substring)
structure SyntaxAtom :=
(info : Option SourceInfo := none) (val : String)
/-- A simple wrapper that should remind you to use the static Declaration instead
of hard-coding the Node Name. -/
structure SyntaxNodeKind :=
-- should be equal to the Name of the Declaration this structure instance was bound to
(name : Name)
/-- Signifies ambiguous Syntax to be disambiguated by the Elaborator. Should have at least two children.
This Node kind is special-cased by `Syntax.reprint` since its children's outputs should not be concatenated. -/
@[pattern] def choice : SyntaxNodeKind := ⟨`Lean.Parser.choice⟩
/-- A nondescriptive kind that can be used for merely grouping Syntax trees into a Node.
This Node kind is special-cased by `Syntax.Format` to be printed as brackets `[...]` without a Node kind. -/
@[pattern] def noKind : SyntaxNodeKind := ⟨`Lean.Parser.noKind⟩
/-- A hygiene marker introduced by a macro expansion. -/
@[derive DecidableEq HasFormat]
def MacroScope := Nat
abbrev macroScopes := List MacroScope
/-
Parsers create `SyntaxNode`'s with the following properties (see implementation of `Combinators.Node`):
- If `args` contains a `Syntax.missing`, then all subsequent elements are also `Syntax.missing`.
- The first argument in `args` is not `Syntax.missing`
Remark: We do create `SyntaxNode`'s with an Empty `args` field (e.g. for representing `Option.none`).
-/
structure SyntaxNode (Syntax : Type) :=
(kind : SyntaxNodeKind)
(args : List Syntax)
-- Lazily propagated scopes. Scopes are pushed inwards when a Node is destructed via `Syntax.asNode`,
-- until an ident or an atom (in which the scopes vanish) is reached.
-- Scopes are stored in a stack with the most recent Scope at the top.
(scopes : macroScopes := [])
structure SyntaxIdent :=
(info : Option SourceInfo := none)
(rawVal : Substring)
(val : Name)
/- A List of overloaded, global names that this identifier could have referred to in the lexical context
where it was parsed.
If the identifier does not resolve to a local binding, it should instead resolve to one of
these preresolved constants. -/
(preresolved : List Name := [])
(scopes : macroScopes := [])
inductive Syntax
| atom (val : SyntaxAtom)
| ident (val : SyntaxIdent)
-- note: use `Syntax.asNode` instead of matching against this Constructor so that
-- macro scopes are propagated
| rawNode (val : SyntaxNode Syntax)
| missing
instance : Inhabited Syntax :=
⟨Syntax.missing⟩
def Substring.toString (s : Substring) : String :=
s.start.extract s.stop
def Substring.ofString (s : String) : Substring :=
⟨s.mkOldIterator, s.mkOldIterator.toEnd⟩
instance Substring.HasToString : HasToString Substring :=
⟨Substring.toString⟩
-- TODO(Sebastian): exhaustively argue why (if?) this is correct
-- The basic idea is List concatenation with elimination of adjacent identical scopes
def macroScopes.flip : macroScopes → macroScopes → macroScopes
| ys (x::xs) := match macroScopes.flip ys xs with
| y::ys := if x = y then ys else x::y::ys
| [] := [x]
| ys [] := ys
namespace Syntax
open Lean.Format
def flipScopes (scopes : macroScopes) : Syntax → Syntax
| (Syntax.ident n) := Syntax.ident {n with scopes := n.scopes.flip scopes}
| (Syntax.rawNode n) := Syntax.rawNode {n with scopes := n.scopes.flip scopes}
| stx := stx
def mkNode (kind : SyntaxNodeKind) (args : List Syntax) :=
Syntax.rawNode { kind := kind, args := args }
/-- Match against `Syntax.rawNode`, propagating lazy macro scopes. -/
def asNode : Syntax → Option (SyntaxNode Syntax)
| (Syntax.rawNode n) := some {n with args := n.args.map (flipScopes n.scopes), scopes := []}
| _ := none
protected def list (args : List Syntax) :=
mkNode noKind args
def kind : Syntax → Option SyntaxNodeKind
| (Syntax.rawNode n) := some n.kind
| _ := none
def isOfKind (k : SyntaxNodeKind) : Syntax → Bool
| (Syntax.rawNode n) := k.name = n.kind.name
| _ := false
section
variables {m : Type → Type} [Monad m] (r : Syntax → m (Option Syntax))
local attribute [instance] monadInhabited
partial def mreplace : Syntax → m Syntax
| stx@(rawNode n) := do
o ← r stx,
match o with
| some stx' := pure stx'
| none := do args' ← n.args.mmap mreplace, pure $ rawNode {n with args := args'}
| stx := do
o ← r stx,
pure $ o.getOrElse stx
def replace := @mreplace Id _
end
/- Remark: the State `String.Iterator` is the `SourceInfo.trailing.stop` of the previous token,
or the beginning of the String. -/
private def updateLeadingAux : Syntax → State String.OldIterator (Option Syntax)
| (atom a@{info := some info, ..}) := do
last ← get,
set info.trailing.stop,
pure $ some $ atom {a with info := some {info with leading := ⟨last, last.nextn (info.pos - last.offset)⟩}}
| (ident id@{info := some info, ..}) := do
last ← get,
set info.trailing.stop,
pure $ some $ ident {id with info := some {info with leading := ⟨last, last.nextn (info.pos - last.offset)⟩}}
| _ := pure none
/-- Set `SourceInfo.leading` according to the trailing stop of the preceding token.
The Result is a round-tripping Syntax tree IF, in the input Syntax tree,
* all leading stops, atom contents, and trailing starts are correct
* trailing stops are between the trailing start and the next leading stop.
Remark: after parsing all `SourceInfo.leading` fields are Empty.
The Syntax argument is the output produced by the Parser for `source`.
This Function "fixes" the `source.leanding` field.
Note that, the `SourceInfo.trailing` fields are correct.
The implementation of this Function relies on this property. -/
def updateLeading (source : String) : Syntax → Syntax :=
λ stx, Prod.fst $ (mreplace updateLeadingAux stx).run source.mkOldIterator
/-- Retrieve the left-most leaf's info in the Syntax tree. -/
partial def getHeadInfo : Syntax → Option SourceInfo
| (atom a) := a.info
| (ident id) := id.info
| (rawNode n) := n.args.foldr (λ s r, getHeadInfo s <|> r) none
| _ := none
def getPos (stx : Syntax) : Option Parsec.Position :=
do i ← stx.getHeadInfo,
pure i.pos
def reprintAtom : SyntaxAtom → String
| ⟨some info, s⟩ := info.leading.toString ++ s ++ info.trailing.toString
| ⟨none, s⟩ := s
partial def reprint : Syntax → Option String
| (atom ⟨some info, s⟩) := pure $ info.leading.toString ++ s ++ info.trailing.toString
| (atom ⟨none, s⟩) := pure s
| (ident id@{info := some info, ..}) := pure $ info.leading.toString ++ id.rawVal.toString ++ info.trailing.toString
| (ident id@{info := none, ..}) := pure id.rawVal.toString
| (rawNode n) :=
if n.kind.name = choice.name then match n.args with
-- should never happen
| [] := failure
-- check that every choice prints the same
| n::ns := do
s ← reprint n,
ss ← ns.mmap reprint,
guard $ ss.all (= s),
pure s
else String.join <$> n.args.mmap reprint
| missing := ""
protected partial def format : Syntax → Format
| (atom ⟨_, s⟩) := fmt $ repr s
| (ident id) :=
let scopes := id.preresolved.map fmt ++ id.scopes.reverse.map fmt in
let scopes := match scopes with [] := fmt "" | _ := bracket "{" (joinSep scopes ", ") "}" in
fmt "`" ++ fmt id.val ++ scopes
| stx@(rawNode n) :=
let scopes := match n.scopes with [] := fmt "" | _ := bracket "{" (joinSep n.scopes.reverse ", ") "}" in
if n.kind.name = `Lean.Parser.noKind then sbracket $ scopes ++ joinSep (n.args.map format) line
else let shorterName := n.kind.name.replacePrefix `Lean.Parser Name.anonymous
in paren $ joinSep ((fmt shorterName ++ scopes) :: n.args.map format) line
| missing := "<missing>"
instance : HasFormat Syntax := ⟨Syntax.format⟩
instance : HasToString Syntax := ⟨toString ∘ fmt⟩
end Syntax
end Parser
end Lean
|
11a1777d0e31c9ae1a1c7180e93b64b5e0f0219d | 4727251e0cd73359b15b664c3170e5d754078599 | /src/topology/algebra/localization.lean | 5f93bac5c3e1e10ef5b899d99651ccea104e12e4 | [
"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 | 1,257 | lean | /-
Copyright (c) 2021 María Inés de Frutos-Fernández. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: María Inés de Frutos-Fernández
-/
import ring_theory.localization.basic
import topology.algebra.ring
/-!
# Localization of topological rings
The topological localization of a topological commutative ring `R` at a submonoid `M` is the ring
`localization M` endowed with the final ring topology of the natural homomorphism sending `x : R`
to the equivalence class of `(x, 1)` in the localization of `R` at a `M`.
## Main Results
- `localization.topological_ring`: The localization of a topological commutative ring at a submonoid
is a topological ring.
-/
variables {R : Type*} [comm_ring R] [topological_space R] {M : submonoid R}
/-- The ring topology on `localization M` coinduced from the natural homomorphism sending `x : R`
to the equivalence class of `(x, 1)`. -/
def localization.ring_topology : ring_topology (localization M) :=
ring_topology.coinduced (localization.monoid_of M).to_fun
instance : topological_space (localization M) :=
localization.ring_topology.to_topological_space
instance : topological_ring (localization M) :=
localization.ring_topology.to_topological_ring
|
b6faae008f182ce003d411f931482808c5e4cf85 | 78269ad0b3c342b20786f60690708b6e328132b0 | /src/library_dev/data/nat/sub.lean | 230e4854170f92e25472532fca95635f0f685301 | [] | no_license | dselsam/library_dev | e74f46010fee9c7b66eaa704654cad0fcd2eefca | 1b4e34e7fb067ea5211714d6d3ecef5132fc8218 | refs/heads/master | 1,610,372,841,675 | 1,497,014,421,000 | 1,497,014,421,000 | 86,526,137 | 0 | 0 | null | 1,490,752,133,000 | 1,490,752,132,000 | null | UTF-8 | Lean | false | false | 6,428 | lean | /-
Copyright (c) 2014 Floris van Doorn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Floris van Doorn, Jeremy Avigad
Subtraction on the natural numbers, as well as min, max, and distance.
-/
namespace nat
/- interaction with inequalities -/
protected theorem le_sub_add (n m : ℕ) : n ≤ n - m + m :=
or.elim (le_total n m)
(suppose n ≤ m, begin rw [sub_eq_zero_of_le this, zero_add], exact this end)
(suppose m ≤ n, begin rw (nat.sub_add_cancel this) end)
protected theorem sub_eq_of_eq_add {n m k : ℕ} (h : k = n + m) : k - n = m :=
begin rw [h, nat.add_sub_cancel_left] end
protected theorem sub_le_sub_left {n m : ℕ} (h : n ≤ m) (k : ℕ) : k - m ≤ k - n :=
begin
cases le.dest h with l hl,
rw [-hl, -nat.sub_sub],
apply sub_le
end
protected theorem lt_of_sub_pos {m n : ℕ} (h : n - m > 0) : m < n :=
lt_of_not_ge
(suppose m ≥ n,
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 {n m k : ℕ} (h : n - k < m - k) : n < m :=
lt_of_not_ge
(suppose m ≤ n,
have m - k ≤ n - k, from nat.sub_le_sub_right this _,
not_le_of_gt h this)
protected theorem lt_of_sub_lt_sub_left {n m k : ℕ} (h : n - m < n - k) : k < m :=
lt_of_not_ge
(suppose m ≤ k,
have n - k ≤ n - m, from nat.sub_le_sub_left this _,
not_le_of_gt h this)
protected theorem sub_lt_self {m n : ℕ} (h₁ : m > 0) (h₂ : n > 0) : 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_of_add_le {m n k : ℕ} (h : m + k ≤ n) : m ≤ n - k :=
calc
m = m + k - k : by rw nat.add_sub_cancel
... ≤ n - k : nat.sub_le_sub_right h k
protected theorem lt_sub_of_add_lt {m n k : ℕ} (h : m + k < n) : m < n - k :=
lt_of_succ_le (nat.le_sub_of_add_le (calc
succ m + k = succ (m + k) : by rw succ_add
... ≤ n : succ_le_of_lt h))
protected theorem add_lt_of_lt_sub {m n k : ℕ} (h : m < n - k) : m + k < n :=
@nat.lt_of_sub_lt_sub_right _ _ k (by rwa nat.add_sub_cancel)
protected theorem sub_lt_of_lt_add {k n m : nat} (h₁ : k < n + m) (h₂ : n ≤ k) : k - n < m :=
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 h₂)
... ≤ n + m - n : nat.sub_le_sub_right this n
... = m : by rw nat.add_sub_cancel_left,
lt_of_succ_le this
/- distance -/
definition dist (n m : ℕ) := (n - m) + (m - n)
theorem dist.def (n m : ℕ) : dist n m = (n - m) + (m - n) := rfl
@[simp]
theorem dist_comm (n m : ℕ) : dist n m = dist m n :=
by simp [dist.def]
@[simp]
theorem dist_self (n : ℕ) : dist n n = 0 :=
by simp [dist.def, nat.sub_self]
theorem eq_of_dist_eq_zero {n m : ℕ} (h : dist n m = 0) : n = m :=
have n - m = 0, from eq_zero_of_add_eq_zero_right h,
have n ≤ m, from nat.le_of_sub_eq_zero this,
have m - n = 0, from eq_zero_of_add_eq_zero_left h,
have m ≤ n, from nat.le_of_sub_eq_zero this,
le_antisymm ‹n ≤ m› ‹m ≤ n›
theorem dist_eq_zero {n m : ℕ} (h : n = m) : dist n m = 0 :=
begin rw [h, dist_self] end
theorem dist_eq_sub_of_le {n m : ℕ} (h : n ≤ m) : dist n m = m - n :=
begin rw [dist.def, sub_eq_zero_of_le h, zero_add] end
theorem dist_eq_sub_of_ge {n m : ℕ} (h : n ≥ m) : dist n m = n - m :=
begin rw [dist_comm], apply dist_eq_sub_of_le h end
theorem dist_zero_right (n : ℕ) : dist n 0 = n :=
eq.trans (dist_eq_sub_of_ge (zero_le n)) (nat.sub_zero n)
theorem dist_zero_left (n : ℕ) : dist 0 n = n :=
eq.trans (dist_eq_sub_of_le (zero_le n)) (nat.sub_zero n)
theorem dist_add_add_right (n k m : ℕ) : dist (n + k) (m + k) = dist n m :=
calc
dist (n + k) (m + k) = ((n + k) - (m + k)) + ((m + k)-(n + k)) : rfl
... = (n - m) + ((m + k) - (n + k)) : by rw nat.add_sub_add_right
... = (n - m) + (m - n) : by rw nat.add_sub_add_right
theorem dist_add_add_left (k n m : ℕ) : dist (k + n) (k + m) = dist n m :=
begin rw [add_comm k n, add_comm k m], apply dist_add_add_right end
theorem dist_eq_intro {n m k l : ℕ} (h : n + m = k + l) : dist n k = dist l m :=
calc
dist n k = dist (n + m) (k + m) : by rw dist_add_add_right
... = dist (k + l) (k + m) : by rw h
... = dist l m : by rw dist_add_add_left
protected theorem sub_lt_sub_add_sub (n m k : ℕ) : n - k ≤ (n - m) + (m - k) :=
or.elim (le_total k m)
(suppose k ≤ m,
begin rw -nat.add_sub_assoc this, apply nat.sub_le_sub_right, apply nat.le_sub_add end)
(suppose k ≥ m,
begin rw [sub_eq_zero_of_le this, add_zero], apply nat.sub_le_sub_left, exact this end)
theorem dist.triangle_inequality (n m k : ℕ) : dist n k ≤ dist n m + dist m k :=
have dist n m + dist m k = (n - m) + (m - k) + ((k - m) + (m - n)), by simp [dist.def],
begin
rw [this, dist.def], apply add_le_add, repeat { apply nat.sub_lt_sub_add_sub }
end
theorem dist_mul_right (n k m : ℕ) : dist (n * k) (m * k) = dist n m * k :=
by rw [dist.def, dist.def, right_distrib, nat.mul_sub_right_distrib, nat.mul_sub_right_distrib]
theorem dist_mul_left (k n m : ℕ) : dist (k * n) (k * m) = k * dist n m :=
by rw [mul_comm k n, mul_comm k m, dist_mul_right, mul_comm]
-- TODO(Jeremy): do when we have max and minx
--lemma dist_eq_max_sub_min {i j : nat} : dist i j = (max i j) - min i j :=
--sorry
/-
or.elim (lt_or_ge i j)
(suppose i < j,
by rw [max_eq_right_of_lt this, min_eq_left_of_lt this, dist_eq_sub_of_lt this])
(suppose i ≥ j,
by rw [max_eq_left this , min_eq_right this, dist_eq_sub_of_ge this])
-/
lemma dist_succ_succ {i j : nat} : dist (succ i) (succ j) = dist i j :=
by simp [dist.def, succ_sub_succ]
lemma dist_pos_of_ne {i j : nat} : i ≠ j → dist i j > 0 :=
assume hne, nat.lt_by_cases
(suppose i < j,
begin rw [dist_eq_sub_of_le (le_of_lt this)], apply nat.sub_pos_of_lt this end)
(suppose i = j, by contradiction)
(suppose i > j,
begin rw [dist_eq_sub_of_ge (le_of_lt this)], apply nat.sub_pos_of_lt this end)
end nat
|
92858adb3a0034d19c435be2d2b40118efd6a14d | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/category_theory/category/Kleisli.lean | e62b3eeda7bb4d221562ee4538b77a0e2c405853 | [
"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 | 1,245 | lean | /-
Copyright (c) 2018 Simon Hudon. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Simon Hudon
The Kleisli construction on the Type category
TODO: generalise this to work with category_theory.monad
-/
import category_theory.category
universes u v
namespace category_theory
def Kleisli (m) [monad.{u v} m] := Type u
def Kleisli.mk (m) [monad.{u v} m] (α : Type u) : Kleisli m := α
instance Kleisli.category_struct {m} [monad m] : category_struct (Kleisli m) :=
{ hom := λ α β, α → m β,
id := λ α x, (pure x : m α),
comp := λ X Y Z f g, f >=> g }
instance Kleisli.category {m} [monad m] [is_lawful_monad m] : category (Kleisli m) :=
by refine { hom := λ α β, α → m β,
id := λ α x, (pure x : m α),
comp := λ X Y Z f g, f >=> g,
id_comp' := _, comp_id' := _, assoc' := _ };
intros; ext; simp only [(>=>)] with functor_norm
@[simp] lemma Kleisli.id_def {m} [monad m] [is_lawful_monad m] (α : Kleisli m) :
𝟙 α = @pure m _ α := rfl
lemma Kleisli.comp_def {m} [monad m] [is_lawful_monad m] (α β γ : Kleisli m)
(xs : α ⟶ β) (ys : β ⟶ γ) (a : α) :
(xs ≫ ys) a = xs a >>= ys := rfl
end category_theory
|
0e59a6ac976e8457958848e1a7aa391ff7bad466 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/order/filter/modeq.lean | 94fee945148c6c8e2c83d108ec9cb638fa131162 | [
"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 | 1,098 | lean | /-
Copyright (c) 2021 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import data.nat.parity
import order.filter.at_top_bot
/-!
# Numbers are frequently modeq to fixed numbers
In this file we prove that `m ≡ d [MOD n]` frequently as `m → ∞`.
-/
open filter
namespace nat
/-- Infinitely many natural numbers are equal to `d` mod `n`. -/
lemma frequently_modeq {n : ℕ} (h : n ≠ 0) (d : ℕ) : ∃ᶠ m in at_top, m ≡ d [MOD n] :=
((tendsto_add_at_top_nat d).comp (tendsto_id.nsmul_at_top h.bot_lt)).frequently $
frequently_of_forall $ λ m, by { simp [nat.modeq_iff_dvd, ← sub_sub] }
lemma frequently_mod_eq {d n : ℕ} (h : d < n) : ∃ᶠ m in at_top, m % n = d :=
by simpa only [nat.modeq, mod_eq_of_lt h] using frequently_modeq h.ne_bot d
lemma frequently_even : ∃ᶠ m : ℕ in at_top, even m :=
by simpa only [even_iff] using frequently_mod_eq zero_lt_two
lemma frequently_odd : ∃ᶠ m : ℕ in at_top, odd m :=
by simpa only [odd_iff] using frequently_mod_eq one_lt_two
end nat
|
1f01ca21e1ec5740638b543a1757c45570d779dc | aa5a655c05e5359a70646b7154e7cac59f0b4132 | /src/Lean/Meta/Tactic/Simp/Rewrite.lean | a23165e9399cf6a4cc86831135f039d7a5c508ba | [
"Apache-2.0"
] | permissive | lambdaxymox/lean4 | ae943c960a42247e06eff25c35338268d07454cb | 278d47c77270664ef29715faab467feac8a0f446 | refs/heads/master | 1,677,891,867,340 | 1,612,500,005,000 | 1,612,500,005,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 4,114 | 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
-/
import Lean.Meta.SynthInstance
import Lean.Meta.Tactic.Simp.Types
namespace Lean.Meta.Simp
/-
Remark: the parameter tag is used for creating trace messages. It is irrelevant otherwise.
-/
def rewrite (e : Expr) (s : DiscrTree SimpLemma) (discharge? : Expr → SimpM (Option Expr)) (tag : String) : SimpM Result := do
let lemmas ← s.getMatch e
if lemmas.isEmpty then
trace[Meta.Tactic.simp]! "no lemmas found for {tag}-rewriting {e}"
return { expr := e }
else
let lemmas := lemmas.insertionSort fun e₁ e₂ => e₁.priority < e₂.priority
for lemma in lemmas do
if let some result ← tryLemma? lemma then
return result
return { expr := e }
where
getLHS (kind : SimpLemmaKind) (type : Expr) : MetaM Expr :=
match kind with
| SimpLemmaKind.pos => return type
| SimpLemmaKind.neg => return type.appArg!
| SimpLemmaKind.eq => return type.appFn!.appArg!
| SimpLemmaKind.iff => return type.appFn!.appArg!
getRHS (kind : SimpLemmaKind) (type : Expr) : MetaM Expr :=
match kind with
| SimpLemmaKind.pos => return mkConst `True
| SimpLemmaKind.neg => return mkConst `False
| SimpLemmaKind.eq => return type.appArg!
| SimpLemmaKind.iff => return type.appArg!
synthesizeArgs (lemma : SimpLemma) (xs : Array Expr) (bis : Array BinderInfo) : SimpM Bool := do
for x in xs, bi in bis do
let type ← inferType x
if bi.isInstImplicit then
match ← trySynthInstance type with
| LOption.some val =>
unless (← isDefEq x val) do
trace[Meta.Tactic.simp.discharge]! "{lemma}, failed to assign instance{indentExpr type}"
return false
| _ =>
trace[Meta.Tactic.simp.discharge]! "{lemma}, failed to synthesize instance{indentExpr type}"
return false
else if (← isProp type <&&> (← instantiateMVars x).isMVar) then
match ← discharge? type with
| some proof =>
unless (← isDefEq x proof) do
trace[Meta.Tactic.simp.discharge]! "{lemma}, failed to assign proof{indentExpr type}"
return false
| none =>
trace[Meta.Tactic.simp.discharge]! "{lemma}, failed to discharge hypotheses{indentExpr type}"
return false
return true
finalizeProof (kind : SimpLemmaKind) (proof : Expr) : MetaM Expr :=
match kind with
| SimpLemmaKind.eq => return proof
| SimpLemmaKind.iff => mkPropExt proof
| SimpLemmaKind.pos => mkEqTrue proof
| SimpLemmaKind.neg => mkEqFalse proof
tryLemma? (lemma : SimpLemma) : SimpM (Option Result) :=
withNewMCtxDepth do
let val ← lemma.getValue
let type ← inferType val
let (xs, bis, type) ← forallMetaTelescopeReducing type
let lhs ← getLHS lemma.kind type
if (← isDefEq lhs e) then
unless (← synthesizeArgs lemma xs bis) do
return none
let proof ← instantiateMVars (mkAppN val xs)
if ← hasAssignableMVar proof then
return none
let rhs ← instantiateMVars (← getRHS lemma.kind type)
if lemma.perm && !Expr.lt rhs e then
trace[Meta.Tactic.simp.unify]! "{lemma}, perm rejected {e} ==> {rhs}"
return none
let proof ← finalizeProof lemma.kind proof
trace[Meta.Tactic.simp.rewrite]! "{lemma}, {e} ==> {rhs}"
return some { expr := rhs, proof? := proof }
else
trace[Meta.Tactic.simp.unify]! "{lemma}, failed to unify {lhs} with {e}"
return none
def preDefault (e : Expr) (discharge? : Expr → SimpM (Option Expr)) : SimpM Step := do
let lemmas ← (← read).simpLemmas
return Step.visit (← rewrite e lemmas.pre discharge? (tag := "pre"))
def postDefault (e : Expr) (discharge? : Expr → SimpM (Option Expr)) : SimpM Step := do
let lemmas ← (← read).simpLemmas
return Step.visit (← rewrite e lemmas.post discharge? (tag := "post"))
end Lean.Meta.Simp
|
421e5279deae1947849c051848f6cc66a837d4ba | 624f6f2ae8b3b1adc5f8f67a365c51d5126be45a | /tests/lean/run/typeclass_diamond.lean | 391e2b6c7b8d17336d35608386647f1756727c9e | [
"Apache-2.0"
] | permissive | mhuisi/lean4 | 28d35a4febc2e251c7f05492e13f3b05d6f9b7af | dda44bc47f3e5d024508060dac2bcb59fd12e4c0 | refs/heads/master | 1,621,225,489,283 | 1,585,142,689,000 | 1,585,142,689,000 | 250,590,438 | 0 | 2 | Apache-2.0 | 1,602,443,220,000 | 1,585,327,814,000 | C | UTF-8 | Lean | false | false | 1,775 | lean | class Top₁ (n : Nat) : Type := (u : Unit := ())
class Bot₁ (n : Nat) : Type := (u : Unit := ())
class Left₁ (n : Nat) : Type := (u : Unit := ())
class Right₁ (n : Nat) : Type := (u : Unit := ())
instance Bot₁Inst : Bot₁ Nat.zero := {}
instance Left₁ToBot₁ (n : Nat) [Left₁ n] : Bot₁ n := {}
instance Right₁ToBot₁ (n : Nat) [Right₁ n] : Bot₁ n := {}
instance Top₁ToLeft₁ (n : Nat) [Top₁ n] : Left₁ n := {}
instance Top₁ToRight₁ (n : Nat) [Top₁ n] : Right₁ n := {}
instance Bot₁ToTopSucc (n : Nat) [Bot₁ n] : Top₁ n.succ := {}
class Top₂ (n : Nat) : Type := (u : Unit := ())
class Bot₂ (n : Nat) : Type := (u : Unit := ())
class Left₂ (n : Nat) : Type := (u : Unit := ())
class Right₂ (n : Nat) : Type := (u : Unit := ())
instance Left₂ToBot₂ (n : Nat) [Left₂ n] : Bot₂ n := {}
instance Right₂ToBot₂ (n : Nat) [Right₂ n] : Bot₂ n := {}
instance Top₂ToLeft₂ (n : Nat) [Top₂ n] : Left₂ n := {}
instance Top₂ToRight₂ (n : Nat) [Top₂ n] : Right₂ n := {}
instance Bot₂ToTopSucc (n : Nat) [Bot₂ n] : Top₂ n.succ := {}
class Top (n : Nat) : Type := (u : Unit := ())
instance Top₁ToTop (n : Nat) [Top₁ n] : Top n := {}
instance Top₂ToTop (n : Nat) [Top₂ n] : Top n := {}
new_frontend
set_option ppOld false
#synth Top Nat.zero.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ
def tst : Top Nat.zero.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ.succ :=
inferInstance
|
ae1d5238c59d0917c0f4dfbf53157ccf4f649085 | 64874bd1010548c7f5a6e3e8902efa63baaff785 | /tests/lean/K_bug.lean | e0743cd33ad73022a61573f38df85ad52afab596 | [
"Apache-2.0"
] | permissive | tjiaqi/lean | 4634d729795c164664d10d093f3545287c76628f | d0ce4cf62f4246b0600c07e074d86e51f2195e30 | refs/heads/master | 1,622,323,796,480 | 1,422,643,069,000 | 1,422,643,069,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 378 | lean | open eq.ops
inductive Nat : Type :=
zero : Nat,
succ : Nat → Nat
namespace Nat
definition pred (n : Nat) := Nat.rec zero (fun m x, m) n
theorem pred_succ (n : Nat) : pred (succ n) = n := rfl
theorem succ_inj {n m : Nat} (H : succ n = succ m) : n = m
:= calc
n = pred (succ n) : pred_succ n⁻¹
... = pred (succ m) : {H}
... = m : pred_succ m
end Nat
|
2c745d2ea7245d1bc9f7baddf71ad0e46592b19c | 01ae0d022f2e2fefdaaa898938c1ac1fbce3b3ab | /categories/examples/graphs.lean | 734eeeb791890f16c94246081a91ed40c690bc97 | [] | no_license | PatrickMassot/lean-category-theory | 0f56a83464396a253c28a42dece16c93baf8ad74 | ef239978e91f2e1c3b8e88b6e9c64c155dc56c99 | refs/heads/master | 1,629,739,187,316 | 1,512,422,659,000 | 1,512,422,659,000 | 113,098,786 | 0 | 0 | null | 1,512,424,022,000 | 1,512,424,022,000 | null | UTF-8 | Lean | false | false | 1,429 | lean | -- Copyright (c) 2017 Scott Morrison. All rights reserved.
-- Released under Apache 2.0 license as described in the file LICENSE.
-- Authors: Scott Morrison
import ..category
open categories
open categories.graphs
namespace categories.examples.graphs
@[applicable] private lemma {u1 v1 u2 v2} GraphHomomorphisms_pointwise_equal
{ C : Graph.{u1 v1} }
{ D : Graph.{u2 v2} }
{ F G : GraphHomomorphism C D }
( objectWitness : ∀ X : C.Obj, F.onObjects X = G.onObjects X )
( morphismWitness : ∀ X Y : C.Obj, ∀ f : C.Hom X Y, ⟦ F.onMorphisms f ⟧ = G.onMorphisms f ) : F = G :=
begin
induction F with F_onObjects F_onMorphisms,
induction G with G_onObjects G_onMorphisms,
have h_objects : F_onObjects = G_onObjects, exact funext objectWitness,
subst h_objects,
have h_morphisms : @F_onMorphisms = @G_onMorphisms,
apply funext, intro X, apply funext, intro Y, apply funext, intro f,
exact morphismWitness X Y f,
subst h_morphisms
end
definition CategoryOfGraphs : Category := {
Obj := Graph,
Hom := GraphHomomorphism,
identity := λ G, {
onObjects := id,
onMorphisms := λ _ _ f, f
},
compose := λ _ _ _ f g, {
onObjects := λ x, g.onObjects (f.onObjects x),
onMorphisms := λ _ _ e, g.onMorphisms (f.onMorphisms e)
},
right_identity := ♯,
left_identity := ♯,
associativity := ♯
}
end categories.examples.graphs |
84990c633dec80b3a66a17de3454e42afdaa5c5a | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/topology/algebra/semigroup.lean | c5ebed196f39244a10022326a7ce3b4c03c14089 | [
"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 | 4,812 | lean | /-
Copyright (c) 2021 David Wärn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: David Wärn
-/
import topology.separation
/-!
# Idempotents in topological semigroups
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
This file provides a sufficient condition for a semigroup `M` to contain an idempotent (i.e. an
element `m` such that `m * m = m `), namely that `M` is a nonempty compact Hausdorff space where
right-multiplication by constants is continuous.
We also state a corresponding lemma guaranteeing that a subset of `M` contains an idempotent.
-/
/-- Any nonempty compact Hausdorff semigroup where right-multiplication is continuous contains
an idempotent, i.e. an `m` such that `m * m = m`. -/
@[to_additive "Any nonempty compact Hausdorff additive semigroup where right-addition is continuous
contains an idempotent, i.e. an `m` such that `m + m = m`"]
lemma exists_idempotent_of_compact_t2_of_continuous_mul_left {M} [nonempty M] [semigroup M]
[topological_space M] [compact_space M] [t2_space M]
(continuous_mul_left : ∀ r : M, continuous (* r)) : ∃ m : M, m * m = m :=
begin
/- We apply Zorn's lemma to the poset of nonempty closed subsemigroups of `M`. It will turn out that
any minimal element is `{m}` for an idempotent `m : M`. -/
let S : set (set M) := {N | is_closed N ∧ N.nonempty ∧ ∀ m m' ∈ N, m * m' ∈ N},
rsuffices ⟨N, ⟨N_closed, ⟨m, hm⟩, N_mul⟩, N_minimal⟩ : ∃ N ∈ S, ∀ N' ∈ S, N' ⊆ N → N' = N,
{ use m,
/- We now have an element `m : M` of a minimal subsemigroup `N`, and want to show `m + m = m`.
We first show that every element of `N` is of the form `m' + m`.-/
have scaling_eq_self : (* m) '' N = N,
{ apply N_minimal,
{ refine ⟨(continuous_mul_left m).is_closed_map _ N_closed, ⟨_, ⟨m, hm, rfl⟩⟩, _⟩,
rintros _ ⟨m'', hm'', rfl⟩ _ ⟨m', hm', rfl⟩,
refine ⟨m'' * m * m', N_mul _ (N_mul _ hm'' _ hm) _ hm', mul_assoc _ _ _⟩ },
{ rintros _ ⟨m', hm', rfl⟩,
exact N_mul _ hm' _ hm } },
/- In particular, this means that `m' * m = m` for some `m'`. We now use minimality again to show
that this holds for all `m' ∈ N`. -/
have absorbing_eq_self : N ∩ {m' | m' * m = m} = N,
{ apply N_minimal,
{ refine ⟨N_closed.inter ((t1_space.t1 m).preimage (continuous_mul_left m)), _, _⟩,
{ rwa ←scaling_eq_self at hm },
{ rintros m'' ⟨mem'', eq'' : _ = m⟩ m' ⟨mem', eq' : _ = m⟩,
refine ⟨N_mul _ mem'' _ mem', _⟩,
rw [set.mem_set_of_eq, mul_assoc, eq', eq''] } },
apply set.inter_subset_left },
/- Thus `m * m = m` as desired. -/
rw ←absorbing_eq_self at hm,
exact hm.2 },
refine zorn_superset _ (λ c hcs hc, _),
refine ⟨⋂₀ c, ⟨is_closed_sInter $ λ t ht, (hcs ht).1, _, λ m hm m' hm', _⟩,
λ s hs, set.sInter_subset_of_mem hs⟩,
{ obtain rfl | hcnemp := c.eq_empty_or_nonempty,
{ rw set.sInter_empty, apply set.univ_nonempty },
convert @is_compact.nonempty_Inter_of_directed_nonempty_compact_closed _ _ _ hcnemp.coe_sort
(coe : c → set M) _ _ _ _,
{ simp only [subtype.range_coe_subtype, set.set_of_mem_eq] } ,
{ refine directed_on.directed_coe (is_chain.directed_on hc.symm) },
exacts [λ i, (hcs i.prop).2.1, λ i, (hcs i.prop).1.is_compact, λ i, (hcs i.prop).1] },
{ rw set.mem_sInter,
exact λ t ht, (hcs ht).2.2 m (set.mem_sInter.mp hm t ht) m' (set.mem_sInter.mp hm' t ht) },
end
/-- A version of `exists_idempotent_of_compact_t2_of_continuous_mul_left` where the idempotent lies
in some specified nonempty compact subsemigroup. -/
@[to_additive exists_idempotent_in_compact_add_subsemigroup "A version of
`exists_idempotent_of_compact_t2_of_continuous_add_left` where the idempotent lies in some specified
nonempty compact additive subsemigroup."]
lemma exists_idempotent_in_compact_subsemigroup {M} [semigroup M] [topological_space M] [t2_space M]
(continuous_mul_left : ∀ r : M, continuous (* r))
(s : set M) (snemp : s.nonempty) (s_compact : is_compact s) (s_add : ∀ x y ∈ s, x * y ∈ s) :
∃ m ∈ s, m * m = m :=
begin
let M' := {m // m ∈ s},
letI : semigroup M' :=
{ mul := λ p q, ⟨p.1 * q.1, s_add _ p.2 _ q.2⟩,
mul_assoc := λ p q r, subtype.eq (mul_assoc _ _ _) },
haveI : compact_space M' := is_compact_iff_compact_space.mp s_compact,
haveI : nonempty M' := nonempty_subtype.mpr snemp,
have : ∀ p : M', continuous (* p) := λ p,
((continuous_mul_left p.1).comp continuous_subtype_val).subtype_mk _,
obtain ⟨⟨m, hm⟩, idem⟩ := exists_idempotent_of_compact_t2_of_continuous_mul_left this,
exact ⟨m, hm, subtype.ext_iff.mp idem⟩
end
|
4263f2e1d42472680fcf020c766b52c1c13430e9 | a4673261e60b025e2c8c825dfa4ab9108246c32e | /src/Lean/Data/OpenDecl.lean | b340867cbca7e0ec44e1493963b020a01fee388d | [
"Apache-2.0"
] | permissive | jcommelin/lean4 | c02dec0cc32c4bccab009285475f265f17d73228 | 2909313475588cc20ac0436e55548a4502050d0a | refs/heads/master | 1,674,129,550,893 | 1,606,415,348,000 | 1,606,415,348,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 761 | 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
-/
import Lean.Data.Name
namespace Lean
inductive OpenDecl :=
| simple (ns : Name) (except : List Name)
| explicit (id : Name) (declName : Name)
namespace OpenDecl
instance : Inhabited OpenDecl := ⟨simple Name.anonymous []⟩
instance : ToString OpenDecl := ⟨fun decl =>
match decl with
| explicit id decl => toString id ++ " → " ++ toString decl
| simple ns ex => toString ns ++ (if ex == [] then "" else " hiding " ++ toString ex)⟩
end OpenDecl
def rootNamespace := `_root_
def removeRoot (n : Name) : Name :=
n.replacePrefix rootNamespace Name.anonymous
end Lean
|
42848c52aef786ca0bca00d95a03a0edeea24cb4 | 947b78d97130d56365ae2ec264df196ce769371a | /src/Lean/Elab/Tactic/Basic.lean | edf36d51291ceafa62dcf371d04e18cff6b7e4d7 | [
"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 | 16,140 | 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.Meta.Tactic.Assumption
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
namespace Elab
open Meta
def goalsToMessageData (goals : List MVarId) : MessageData :=
MessageData.joinSep (goals.map $ MessageData.ofGoal) (Format.line ++ Format.line)
def Term.reportUnsolvedGoals (goals : List MVarId) : TermElabM Unit := do
throwError $ "unsolved goals" ++ Format.line ++ goalsToMessageData goals
namespace Tactic
structure Context :=
(main : MVarId)
structure State :=
(goals : List MVarId)
instance State.inhabited : Inhabited State := ⟨{ goals := [] }⟩
structure BacktrackableState :=
(env : Environment)
(mctx : MetavarContext)
(goals : List MVarId)
abbrev TacticM := ReaderT Context $ StateRefT State $ TermElabM
abbrev Tactic := Syntax → TacticM Unit
def saveBacktrackableState : TacticM BacktrackableState := do
env ← getEnv;
mctx ← getMCtx;
s ← get;
pure { env := env, mctx := mctx, goals := s.goals }
def BacktrackableState.restore (b : BacktrackableState) : TacticM Unit := do
setEnv b.env;
setMCtx b.mctx;
modify fun s => { s with goals := b.goals }
@[inline] protected def catch {α} (x : TacticM α) (h : Exception → TacticM α) : TacticM α := do
b ← saveBacktrackableState;
catch x (fun ex => do b.restore; h ex)
@[inline] protected def orelse {α} (x y : TacticM α) : TacticM α := do
catch x (fun _ => y)
instance monadExcept : MonadExcept Exception TacticM :=
{ throw := fun _ => throw,
catch := fun _ x h => Tactic.catch x h }
instance hasOrElse {α} : HasOrelse (TacticM α) := ⟨Tactic.orelse⟩
structure SavedState :=
(core : Core.State)
(meta : Meta.State)
(term : Term.State)
(tactic : State)
instance SavedState.inhabited : Inhabited SavedState := ⟨⟨arbitrary _, arbitrary _, arbitrary _, arbitrary _⟩⟩
def saveAllState : TacticM SavedState := do
core ← getThe Core.State;
meta ← getThe Meta.State;
term ← getThe Term.State;
tactic ← get;
pure { core := core, meta := meta, term := term, tactic := tactic }
def SavedState.restore (s : SavedState) : TacticM Unit := do
set s.core; set s.meta; set s.term; set s.tactic
@[inline] def liftTermElabM {α} (x : TermElabM α) : TacticM α :=
liftM x
@[inline] def liftMetaM {α} (x : MetaM α) : TacticM α :=
liftTermElabM $ Term.liftMetaM x
def ensureHasType (expectedType? : Option Expr) (e : Expr) : TacticM Expr := liftTermElabM $ Term.ensureHasType expectedType? e
def reportUnsolvedGoals (goals : List MVarId) : TacticM Unit := liftTermElabM $ Term.reportUnsolvedGoals goals
protected def getCurrMacroScope : TacticM MacroScope := do ctx ← readThe Term.Context; pure ctx.currMacroScope
protected def getMainModule : TacticM Name := do env ← getEnv; pure env.mainModule
unsafe def mkTacticAttribute : IO (KeyedDeclsAttribute Tactic) :=
mkElabAttribute Tactic `Lean.Elab.Tactic.tacticElabAttribute `builtinTactic `tactic `Lean.Parser.Tactic `Lean.Elab.Tactic.Tactic "tactic"
@[init mkTacticAttribute] constant tacticElabAttribute : KeyedDeclsAttribute Tactic := arbitrary _
private def evalTacticUsing (s : SavedState) (stx : Syntax) : List Tactic → TacticM Unit
| [] => do
throwErrorAt stx ("unexpected syntax" ++ MessageData.nest 2 (Format.line ++ stx))
| (evalFn::evalFns) => catch (evalFn stx)
(fun ex => match ex with
| Exception.error _ _ =>
match evalFns with
| [] => throw ex
| _ => do s.restore; evalTacticUsing evalFns
| Exception.internal id =>
if id == unsupportedSyntaxExceptionId then do
s.restore; evalTacticUsing evalFns
else
throw ex)
/- Elaborate `x` with `stx` on the macro stack -/
@[inline] def withMacroExpansion {α} (beforeStx afterStx : Syntax) (x : TacticM α) : TacticM α :=
adaptTheReader Term.Context (fun ctx => { ctx with macroStack := { before := beforeStx, after := afterStx } :: ctx.macroStack }) x
@[specialize] private def expandTacticMacroFns (evalTactic : Syntax → TacticM Unit) (stx : Syntax) : List Macro → TacticM Unit
| [] => throwErrorAt stx ("tactic '" ++ toString stx.getKind ++ "' has not been implemented")
| m::ms => do
scp ← getCurrMacroScope;
catch
(do stx' ← adaptMacro m stx; evalTactic stx')
(fun ex => match ms with
| [] => throw ex
| _ => expandTacticMacroFns ms)
@[inline] def expandTacticMacro (evalTactic : Syntax → TacticM Unit) (stx : Syntax) : TacticM Unit := do
env ← getEnv;
let k := stx.getKind;
let table := (macroAttribute.ext.getState env).table;
let macroFns := (table.find? k).getD [];
expandTacticMacroFns evalTactic stx macroFns
partial def evalTactic : Syntax → TacticM Unit
| stx => 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 fun _ => stx;
env ← getEnv;
s ← saveAllState;
let table := (tacticElabAttribute.ext.getState env).table;
let k := stx.getKind;
match table.find? k with
| some evalFns => evalTacticUsing s stx evalFns
| none => expandTacticMacro evalTactic stx
| _ => throwError "unexpected command"
/-- Adapt a syntax transformation to a regular tactic evaluator. -/
def adaptExpander (exp : Syntax → TacticM Syntax) : Tactic :=
fun stx => do
stx' ← exp stx;
withMacroExpansion stx stx' $ evalTactic stx'
def getGoals : TacticM (List MVarId) := do s ← get; pure s.goals
def setGoals (gs : List MVarId) : TacticM Unit := modify $ fun s => { s with goals := gs }
def appendGoals (gs : List MVarId) : TacticM Unit := modify $ fun s => { s with goals := s.goals ++ gs }
def pruneSolvedGoals : TacticM Unit := do
gs ← getGoals;
gs ← gs.filterM $ fun g => not <$> isExprMVarAssigned g;
setGoals gs
def getUnsolvedGoals : TacticM (List MVarId) := do pruneSolvedGoals; getGoals
def getMainGoal : TacticM (MVarId × List MVarId) := do (g::gs) ← getUnsolvedGoals | throwError "no goals to be solved"; pure (g, gs)
def getMainTag : TacticM Name := do
(g, _) ← getMainGoal;
mvarDecl ← getMVarDecl g;
pure mvarDecl.userName
def ensureHasNoMVars (e : Expr) : TacticM Unit := do
e ← instantiateMVars e;
pendingMVars ← getMVars e;
liftM $ Term.logUnassignedUsingErrorInfos pendingMVars;
when e.hasExprMVar $ throwError ("tactic failed, resulting expression contains metavariables" ++ indentExpr e)
def withMainMVarContext {α} (x : TacticM α) : TacticM α := do
(mvarId, _) ← getMainGoal;
withMVarContext mvarId x
@[inline] def liftMetaMAtMain {α} (x : MVarId → MetaM α) : TacticM α := do
(g, _) ← getMainGoal;
withMVarContext g $ liftMetaM $ x g
@[inline] def liftMetaTacticAux {α} (tactic : MVarId → MetaM (α × List MVarId)) : TacticM α := do
(g, gs) ← getMainGoal;
withMVarContext g $ do
(a, gs') ← liftMetaM $ tactic g;
setGoals (gs' ++ gs);
pure a
@[inline] def liftMetaTactic (tactic : MVarId → MetaM (List MVarId)) : TacticM Unit :=
liftMetaTacticAux (fun mvarId => do gs ← tactic mvarId; pure ((), gs))
def done : TacticM Unit := do
gs ← getUnsolvedGoals;
unless gs.isEmpty $ reportUnsolvedGoals gs
@[builtinTactic Lean.Parser.Tactic.«done»] def evalDone : Tactic :=
fun _ => done
def focusAux {α} (tactic : TacticM α) : TacticM α := do
(g, gs) ← getMainGoal;
setGoals [g];
a ← tactic;
gs' ← getGoals;
setGoals (gs' ++ gs);
pure a
def focus {α} (tactic : TacticM α) : TacticM α :=
focusAux (do a ← tactic; done; pure a)
def try? {α} (tactic : TacticM α) : TacticM (Option α) :=
catch (do a ← tactic; pure (some a)) (fun _ => pure none)
def try {α} (tactic : TacticM α) : TacticM Bool :=
catch (do tactic; pure true) (fun _ => 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
mctx ← getMCtx;
let numAnonymous := newGoals.foldl (fun n g => if mctx.isAnonymousMVar g then n + 1 else n) 0;
modifyMCtx fun mctx =>
let (mctx, _) := newGoals.foldl
(fun (acc : MetavarContext × Nat) (g : MVarId) =>
let (mctx, idx) := acc;
if mctx.isAnonymousMVar g then
if numAnonymous == 1 then
(mctx.renameMVar g parentTag, idx+1)
else
(mctx.renameMVar g (parentTag ++ newSuffix.appendIndexAfter idx), idx+1)
else
acc)
(mctx, 1);
mctx
def evalSeq : Tactic :=
fun stx => (stx.getArg 0).forSepArgsM evalTactic
@[builtinTactic seq1] def evalSeq1 : Tactic := evalSeq
@[builtinTactic tacticSeq1Indented] def evalTacticSeq1Indented : Tactic := evalSeq
@[builtinTactic tacticSeqBracketed] def evalTacticSeqBracketed : Tactic :=
fun stx => withRef (stx.getArg 2) $ focus $ (stx.getArg 1).forSepArgsM evalTactic
@[builtinTactic Parser.Tactic.focus] def evalFocus : Tactic :=
fun stx => focus $ evalTactic (stx.getArg 1)
@[builtinTactic paren] def evalParen : Tactic :=
fun stx => evalSeq1 (stx.getArg 1)
@[builtinTactic tacticSeq] def evalTacticSeq : Tactic :=
fun stx => evalTactic (stx.getArg 0)
partial def evalChoiceAux (tactics : Array Syntax) : Nat → TacticM Unit
| i =>
if h : i < tactics.size then
let tactic := tactics.get ⟨i, h⟩;
catchInternalId unsupportedSyntaxExceptionId
(evalTactic tactic)
(fun _ => evalChoiceAux (i+1))
else
throwUnsupportedSyntax
@[builtinTactic choice] def evalChoice : Tactic :=
fun stx => evalChoiceAux stx.getArgs 0
@[builtinTactic skip] def evalSkip : Tactic :=
fun stx => pure ()
@[builtinTactic failIfSuccess] def evalFailIfSuccess : Tactic :=
fun stx =>
let tactic := stx.getArg 1;
whenM
(catch
(do evalTactic tactic; pure true)
(fun _ => pure false))
(throwError ("tactic succeeded"))
@[builtinTactic traceState] def evalTraceState : Tactic :=
fun stx => do
gs ← getUnsolvedGoals;
logInfo (goalsToMessageData gs)
@[builtinTactic Lean.Parser.Tactic.assumption] def evalAssumption : Tactic :=
fun stx => liftMetaTactic $ fun mvarId => do Meta.assumption mvarId; pure []
private def introStep (n : Name) : TacticM Unit :=
liftMetaTactic $ fun mvarId => do (_, mvarId) ← Meta.intro mvarId n; pure [mvarId]
@[builtinTactic Lean.Parser.Tactic.intro] def evalIntro : Tactic :=
fun stx => match_syntax stx with
| `(tactic| intro) => liftMetaTactic $ fun mvarId => do (_, mvarId) ← Meta.intro1 mvarId; pure [mvarId]
| `(tactic| intro $h:ident) => introStep h.getId
| `(tactic| intro _) => introStep `_
| `(tactic| intro $pat:term) => do
stxNew ← `(tactic| intro h; match h with | $pat:term => _; clear h);
withMacroExpansion stx stxNew $ evalTactic stxNew
| `(tactic| intro $hs:term*) => do
let h0 := hs.get! 0;
let hs := hs.extract 1 hs.size;
stxNew ← `(tactic| intro $h0:term; intro $hs:term*);
withMacroExpansion stx stxNew $ evalTactic stxNew
| _ => throwUnsupportedSyntax
@[builtinTactic Lean.Parser.Tactic.introMatch] def evalIntroMatch : Tactic :=
fun stx => do
let matchAlts := stx.getArg 1;
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
| _ => 0
@[builtinTactic «intros»] def evalIntros : Tactic :=
fun stx => match_syntax stx with
| `(tactic| intros) => liftMetaTactic $ fun mvarId => do
type ← Meta.getMVarType mvarId;
type ← instantiateMVars type;
let n := getIntrosSize type;
(_, mvarId) ← Meta.introN mvarId n;
pure [mvarId]
| `(tactic| intros $ids*) => liftMetaTactic $ fun mvarId => do
(_, mvarId) ← Meta.introN mvarId ids.size (ids.map Syntax.getId).toList;
pure [mvarId]
| _ => throwUnsupportedSyntax
def getFVarId (id : Syntax) : TacticM FVarId :=
withRef id do
fvar? ← liftTermElabM $ Term.isLocalIdent? id;
match fvar? with
| some fvar => pure fvar.fvarId!
| none => throwError ("unknown variable '" ++ toString id.getId ++ "'")
def getFVarIds (ids : Array Syntax) : TacticM (Array FVarId) := do
withMainMVarContext $ ids.mapM getFVarId
@[builtinTactic Lean.Parser.Tactic.revert] def evalRevert : Tactic :=
fun stx => match_syntax stx with
| `(tactic| revert $hs*) => do
(g, gs) ← getMainGoal;
fvarIds ← getFVarIds hs;
(_, g) ← liftMetaM $ Meta.revert g fvarIds;
setGoals (g :: gs)
| _ => throwUnsupportedSyntax
/- Sort free variables using an order `x < y` iff `x` was defined after `y` -/
private def sortFVarIds (fvarIds : Array FVarId) : TacticM (Array FVarId) :=
withMainMVarContext do
lctx ← getLCtx;
pure $ 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_syntax stx with
| `(tactic| clear $hs*) => do
fvarIds ← getFVarIds hs;
fvarIds ← sortFVarIds fvarIds;
fvarIds.forM fun fvarId => do
(g, gs) ← getMainGoal;
withMVarContext g do
g ← liftMetaM $ clear g fvarId;
setGoals (g :: gs)
| _ => throwUnsupportedSyntax
def forEachVar (hs : Array Syntax) (tac : MVarId → FVarId → MetaM MVarId) : TacticM Unit :=
hs.forM $ fun h => do
(g, gs) ← getMainGoal;
withMVarContext g do
fvarId ← getFVarId h;
g ← liftMetaM $ tac g fvarId;
setGoals (g :: gs)
@[builtinTactic Lean.Parser.Tactic.subst] def evalSubst : Tactic :=
fun stx => match_syntax 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? (gs : List MVarId) (tag : Name) : TacticM (Option MVarId) := do
g? ← gs.findM? (fun g => do mvarDecl ← getMVarDecl g; pure $ tag.isSuffixOf mvarDecl.userName);
match g? with
| some g => pure g
| none => gs.findM? (fun g => do mvarDecl ← getMVarDecl g; pure $ tag.isPrefixOf mvarDecl.userName)
@[builtinTactic «case»] def evalCase : Tactic :=
fun stx => match_syntax stx with
| `(tactic| case $tag => $tac:tacticSeq) => do
let tag := tag.getId;
gs ← getUnsolvedGoals;
some g ← findTag? gs tag | throwError "tag not found";
let gs := gs.erase g;
setGoals [g];
savedTag ← liftM $ getMVarTag g;
liftM $ setMVarTag g Name.anonymous;
finally (evalTactic tac) (liftM $ setMVarTag g savedTag);
done;
setGoals gs
| _ => throwUnsupportedSyntax
@[builtinTactic «orelse»] def evalOrelse : Tactic :=
fun stx => match_syntax stx with
| `(tactic| $tac1 <|> $tac2) => evalTactic tac1 <|> evalTactic tac2
| _ => throwUnsupportedSyntax
@[init] private def regTraceClasses : IO Unit := do
registerTraceClass `Elab.tactic;
pure ()
@[inline] def TacticM.run {α} (x : TacticM α) (ctx : Context) (s : State) : TermElabM (α × State) :=
(x.run ctx).run s
@[inline] def TacticM.run' {α} (x : TacticM α) (ctx : Context) (s : State) : TermElabM α :=
Prod.fst <$> x.run ctx s
end Tactic
end Elab
end Lean
|
37a53c7096cf771474bb290e96ad501b096d5df0 | a0e23cfdd129a671bf3154ee1a8a3a72bf4c7940 | /stage0/src/Lean/Elab/StructInst.lean | d18bdd351994a038dba728b52a4d73aa1f2ee162 | [
"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 | 34,674 | 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
-/
import Lean.Util.FindExpr
import Lean.Parser.Term
import Lean.Elab.App
import Lean.Elab.Binders
namespace Lean.Elab.Term.StructInst
open Std (HashMap)
open Meta
/-
Structure instances are of the form:
"{" >> optional (atomic (termParser >> " with "))
>> manyIndent (group ((structInstFieldAbbrev <|> structInstField) >> optional ", "))
>> optEllipsis
>> optional (" : " >> termParser)
>> " }"
-/
@[builtinMacro Lean.Parser.Term.structInst] def expandStructInstExpectedType : Macro := fun stx =>
let expectedArg := stx[4]
if expectedArg.isNone then
Macro.throwUnsupported
else
let expected := expectedArg[1]
let stxNew := stx.setArg 4 mkNullNode
`(($stxNew : $expected))
/-
If `stx` is of the form `{ s with ... }` and `s` is not a local variable, expand into `let src := s; { src with ... }`.
Note that this one is not a `Macro` because we need to access the local context.
-/
private def expandNonAtomicExplicitSource (stx : Syntax) : TermElabM (Option Syntax) :=
withFreshMacroScope do
let sourceOpt := stx[1]
if sourceOpt.isNone then
pure none
else
let source := sourceOpt[0]
match (← isLocalIdent? source) with
| some _ => pure none
| none =>
if source.isMissing then
throwAbortTerm
else
let src ← `(src)
let sourceOpt := sourceOpt.setArg 0 src
let stxNew := stx.setArg 1 sourceOpt
`(let src := $source; $stxNew)
inductive Source where
| none -- structure instance source has not been provieded
| implicit (stx : Syntax) -- `..`
| explicit (stx : Syntax) (src : Expr) -- `src with`
deriving Inhabited
def Source.isNone : Source → Bool
| Source.none => true
| _ => false
def setStructSourceSyntax (structStx : Syntax) : Source → Syntax
| Source.none => (structStx.setArg 1 mkNullNode).setArg 3 mkNullNode
| Source.implicit stx => (structStx.setArg 1 mkNullNode).setArg 3 stx
| Source.explicit stx _ => (structStx.setArg 1 stx).setArg 3 mkNullNode
private def getStructSource (stx : Syntax) : TermElabM Source :=
withRef stx do
let explicitSource := stx[1]
let implicitSource := stx[3]
if explicitSource.isNone && implicitSource[0].isNone then
return Source.none
else if explicitSource.isNone then
return Source.implicit implicitSource
else if implicitSource[0].isNone then
let fvar? ← isLocalIdent? explicitSource[0]
match fvar? with
| none => unreachable! -- expandNonAtomicExplicitSource must have been used when we get here
| some src => return Source.explicit explicitSource src
else
throwError "invalid structure instance `with` and `..` cannot be used together"
/-
We say a `{ ... }` notation is a `modifyOp` if it contains only one
```
def structInstArrayRef := leading_parser "[" >> termParser >>"]"
```
-/
private def isModifyOp? (stx : Syntax) : TermElabM (Option Syntax) := do
let s? ← stx[2].getArgs.foldlM (init := none) fun s? p =>
/- p is of the form `(group ((structInstFieldAbbrev <|> structInstField) >> optional ", "))` -/
let arg := p[0]
if arg.getKind == ``Lean.Parser.Term.structInstField then
/- Remark: the syntax for `structInstField` is
```
def structInstLVal := leading_parser (ident <|> numLit <|> structInstArrayRef) >> many (group ("." >> (ident <|> numLit)) <|> structInstArrayRef)
def structInstField := leading_parser structInstLVal >> " := " >> termParser
```
-/
let lval := arg[0]
let k := lval[0].getKind
if k == ``Lean.Parser.Term.structInstArrayRef then
match s? with
| none => pure (some arg)
| some s =>
if s.getKind == ``Lean.Parser.Term.structInstArrayRef then
throwErrorAt arg "invalid \{...} notation, at most one `[..]` at a given level"
else
throwErrorAt arg "invalid \{...} notation, can't mix field and `[..]` at a given level"
else
match s? with
| none => pure (some arg)
| some s =>
if s.getKind == ``Lean.Parser.Term.structInstArrayRef then
throwErrorAt arg "invalid \{...} notation, can't mix field and `[..]` at a given level"
else
pure s?
else
pure s?
match s? with
| none => pure none
| some s => if s[0][0].getKind == ``Lean.Parser.Term.structInstArrayRef then pure s? else pure none
private def elabModifyOp (stx modifyOp source : Syntax) (expectedType? : Option Expr) : TermElabM Expr := do
let cont (val : Syntax) : TermElabM Expr := do
let lval := modifyOp[0][0]
let idx := lval[1]
let self := source[0]
let stxNew ← `($(self).modifyOp (idx := $idx) (fun s => $val))
trace[Elab.struct.modifyOp] "{stx}\n===>\n{stxNew}"
withMacroExpansion stx stxNew <| elabTerm stxNew expectedType?
trace[Elab.struct.modifyOp] "{modifyOp}\nSource: {source}"
let rest := modifyOp[0][1]
if rest.isNone then
cont modifyOp[2]
else
let s ← `(s)
let valFirst := rest[0]
let valFirst := if valFirst.getKind == ``Lean.Parser.Term.structInstArrayRef then valFirst else valFirst[1]
let restArgs := rest.getArgs
let valRest := mkNullNode restArgs[1:restArgs.size]
let valField := modifyOp.setArg 0 <| Syntax.node ``Parser.Term.structInstLVal #[valFirst, valRest]
let valSource := source.modifyArg 0 fun _ => s
let val := stx.setArg 1 valSource
let val := val.setArg 2 <| mkNullNode #[mkNullNode #[valField, mkNullNode]]
trace[Elab.struct.modifyOp] "{stx}\nval: {val}"
cont val
/- Get structure name and elaborate explicit source (if available) -/
private def getStructName (stx : Syntax) (expectedType? : Option Expr) (sourceView : Source) : TermElabM (Name × Expr) := do
tryPostponeIfNoneOrMVar expectedType?
let useSource : Unit → TermElabM (Name × Expr) := fun _ =>
match sourceView, expectedType? with
| Source.explicit _ src, _ => do
let srcType ← inferType src
let srcType ← whnf srcType
tryPostponeIfMVar srcType
match srcType.getAppFn with
| Expr.const constName _ _ => return (constName, srcType)
| _ => throwUnexpectedExpectedType srcType "source"
| _, some expectedType => throwUnexpectedExpectedType expectedType
| _, none => throwUnknownExpectedType
match expectedType? with
| none => useSource ()
| some expectedType =>
let expectedType ← whnf expectedType
match expectedType.getAppFn with
| Expr.const constName _ _ => return (constName, expectedType)
| _ => useSource ()
where
throwUnknownExpectedType :=
throwError "invalid \{...} notation, expected type is not known"
throwUnexpectedExpectedType type (kind := "expected") := do
let type ← instantiateMVars type
if type.getAppFn.isMVar then
throwUnknownExpectedType
else
throwError "invalid \{...} notation, {kind} type is not of the form (C ...){indentExpr type}"
inductive FieldLHS where
| fieldName (ref : Syntax) (name : Name)
| fieldIndex (ref : Syntax) (idx : Nat)
| modifyOp (ref : Syntax) (index : Syntax)
deriving Inhabited
instance : ToFormat FieldLHS := ⟨fun lhs =>
match lhs with
| FieldLHS.fieldName _ n => fmt n
| FieldLHS.fieldIndex _ i => fmt i
| FieldLHS.modifyOp _ i => "[" ++ i.prettyPrint ++ "]"⟩
inductive FieldVal (σ : Type) where
| term (stx : Syntax) : FieldVal σ
| nested (s : σ) : FieldVal σ
| default : FieldVal σ -- mark that field must be synthesized using default value
deriving Inhabited
structure Field (σ : Type) where
ref : Syntax
lhs : List FieldLHS
val : FieldVal σ
expr? : Option Expr := none
deriving Inhabited
def Field.isSimple {σ} : Field σ → Bool
| { lhs := [_], .. } => true
| _ => false
inductive Struct where
| mk (ref : Syntax) (structName : Name) (fields : List (Field Struct)) (source : Source)
deriving Inhabited
abbrev Fields := List (Field Struct)
/- true if all fields of the given structure are marked as `default` -/
partial def Struct.allDefault : Struct → Bool
| ⟨_, _, fields, _⟩ => fields.all fun ⟨_, _, val, _⟩ => match val with
| FieldVal.term _ => false
| FieldVal.default => true
| FieldVal.nested s => allDefault s
def Struct.ref : Struct → Syntax
| ⟨ref, _, _, _⟩ => ref
def Struct.structName : Struct → Name
| ⟨_, structName, _, _⟩ => structName
def Struct.fields : Struct → Fields
| ⟨_, _, fields, _⟩ => fields
def Struct.source : Struct → Source
| ⟨_, _, _, s⟩ => s
def formatField (formatStruct : Struct → Format) (field : Field Struct) : Format :=
Format.joinSep field.lhs " . " ++ " := " ++
match field.val with
| FieldVal.term v => v.prettyPrint
| FieldVal.nested s => formatStruct s
| FieldVal.default => "<default>"
partial def formatStruct : Struct → Format
| ⟨_, structName, fields, source⟩ =>
let fieldsFmt := Format.joinSep (fields.map (formatField formatStruct)) ", "
match source with
| Source.none => "{" ++ fieldsFmt ++ "}"
| Source.implicit _ => "{" ++ fieldsFmt ++ " .. }"
| Source.explicit _ src => "{" ++ format src ++ " with " ++ fieldsFmt ++ "}"
instance : ToFormat Struct := ⟨formatStruct⟩
instance : ToString Struct := ⟨toString ∘ format⟩
instance : ToFormat (Field Struct) := ⟨formatField formatStruct⟩
instance : ToString (Field Struct) := ⟨toString ∘ format⟩
/-
Recall that `structInstField` elements have the form
```
def structInstField := leading_parser structInstLVal >> " := " >> termParser
def structInstLVal := leading_parser (ident <|> numLit <|> structInstArrayRef) >> many (("." >> (ident <|> numLit)) <|> structInstArrayRef)
def structInstArrayRef := leading_parser "[" >> termParser >>"]"
```
-/
-- Remark: this code relies on the fact that `expandStruct` only transforms `fieldLHS.fieldName`
def FieldLHS.toSyntax (first : Bool) : FieldLHS → Syntax
| FieldLHS.modifyOp stx _ => stx
| FieldLHS.fieldName stx name => if first then mkIdentFrom stx name else mkGroupNode #[mkAtomFrom stx ".", mkIdentFrom stx name]
| FieldLHS.fieldIndex stx _ => if first then stx else mkGroupNode #[mkAtomFrom stx ".", stx]
def FieldVal.toSyntax : FieldVal Struct → Syntax
| FieldVal.term stx => stx
| _ => unreachable!
def Field.toSyntax : Field Struct → Syntax
| field =>
let stx := field.ref
let stx := stx.setArg 2 field.val.toSyntax
match field.lhs with
| first::rest => stx.setArg 0 <| mkNullNode #[first.toSyntax true, mkNullNode <| rest.toArray.map (FieldLHS.toSyntax false) ]
| _ => unreachable!
private def toFieldLHS (stx : Syntax) : MacroM FieldLHS :=
if stx.getKind == ``Lean.Parser.Term.structInstArrayRef then
return FieldLHS.modifyOp stx stx[1]
else
-- Note that the representation of the first field is different.
let stx := if stx.getKind == groupKind then stx[1] else stx
if stx.isIdent then
return FieldLHS.fieldName stx stx.getId.eraseMacroScopes
else match stx.isFieldIdx? with
| some idx => return FieldLHS.fieldIndex stx idx
| none => Macro.throwError "unexpected structure syntax"
private def mkStructView (stx : Syntax) (structName : Name) (source : Source) : MacroM Struct := do
/- Recall that `stx` is of the form
```
leading_parser "{" >> optional (atomic (termParser >> " with "))
>> manyIndent (group ((structInstFieldAbbrev <|> structInstField) >> optional ", "))
>> optional ".."
>> optional (" : " >> termParser)
>> " }"
```
-/
let fieldsStx ← stx[2].getArgs.mapM fun stx =>
let stx := stx[0]
if stx.getKind == ``Lean.Parser.Term.structInstField then
return stx
else
let id := stx[0]
`(Lean.Parser.Term.structInstField| $id:ident := $id:ident)
let fields ← fieldsStx.toList.mapM fun fieldStx => do
let val := fieldStx[2]
let first ← toFieldLHS fieldStx[0][0]
let rest ← fieldStx[0][1].getArgs.toList.mapM toFieldLHS
pure { ref := fieldStx, lhs := first :: rest, val := FieldVal.term val : Field Struct }
pure ⟨stx, structName, fields, source⟩
def Struct.modifyFieldsM {m : Type → Type} [Monad m] (s : Struct) (f : Fields → m Fields) : m Struct :=
match s with
| ⟨ref, structName, fields, source⟩ => return ⟨ref, structName, (← f fields), source⟩
def Struct.modifyFields (s : Struct) (f : Fields → Fields) : Struct :=
Id.run <| s.modifyFieldsM f
def Struct.setFields (s : Struct) (fields : Fields) : Struct :=
s.modifyFields fun _ => fields
private def expandCompositeFields (s : Struct) : Struct :=
s.modifyFields fun fields => fields.map fun field => match field with
| { lhs := FieldLHS.fieldName ref (Name.str Name.anonymous _ _) :: rest, .. } => field
| { lhs := FieldLHS.fieldName ref n@(Name.str _ _ _) :: rest, .. } =>
let newEntries := n.components.map <| FieldLHS.fieldName ref
{ field with lhs := newEntries ++ rest }
| _ => field
private def expandNumLitFields (s : Struct) : TermElabM Struct :=
s.modifyFieldsM fun fields => do
let env ← getEnv
let fieldNames := getStructureFields env s.structName
fields.mapM fun field => match field with
| { lhs := FieldLHS.fieldIndex ref idx :: rest, .. } =>
if idx == 0 then throwErrorAt ref "invalid field index, index must be greater than 0"
else if idx > fieldNames.size then throwErrorAt ref "invalid field index, structure has only #{fieldNames.size} fields"
else pure { field with lhs := FieldLHS.fieldName ref fieldNames[idx - 1] :: rest }
| _ => pure field
/- For example, consider the following structures:
```
structure A where
x : Nat
structure B extends A where
y : Nat
structure C extends B where
z : Bool
```
This method expands parent structure fields using the path to the parent structure.
For example,
```
{ x := 0, y := 0, z := true : C }
```
is expanded into
```
{ toB.toA.x := 0, toB.y := 0, z := true : C }
```
-/
private def expandParentFields (s : Struct) : TermElabM Struct := do
let env ← getEnv
s.modifyFieldsM fun fields => fields.mapM fun field => match field with
| { lhs := FieldLHS.fieldName ref fieldName :: rest, .. } =>
match findField? env s.structName fieldName with
| none => throwErrorAt ref "'{fieldName}' is not a field of structure '{s.structName}'"
| some baseStructName =>
if baseStructName == s.structName then pure field
else match getPathToBaseStructure? env baseStructName s.structName with
| some path => do
let path := path.map fun funName => match funName with
| Name.str _ s _ => FieldLHS.fieldName ref (Name.mkSimple s)
| _ => unreachable!
pure { field with lhs := path ++ field.lhs }
| _ => throwErrorAt ref "failed to access field '{fieldName}' in parent structure"
| _ => pure field
private abbrev FieldMap := HashMap Name Fields
private def mkFieldMap (fields : Fields) : TermElabM FieldMap :=
fields.foldlM (init := {}) fun fieldMap field =>
match field.lhs with
| FieldLHS.fieldName _ fieldName :: rest =>
match fieldMap.find? fieldName with
| some (prevField::restFields) =>
if field.isSimple || prevField.isSimple then
throwErrorAt field.ref "field '{fieldName}' has already beed specified"
else
return fieldMap.insert fieldName (field::prevField::restFields)
| _ => return fieldMap.insert fieldName [field]
| _ => unreachable!
private def isSimpleField? : Fields → Option (Field Struct)
| [field] => if field.isSimple then some field else none
| _ => none
private def getFieldIdx (structName : Name) (fieldNames : Array Name) (fieldName : Name) : TermElabM Nat := do
match fieldNames.findIdx? fun n => n == fieldName with
| some idx => pure idx
| none => throwError "field '{fieldName}' is not a valid field of '{structName}'"
private def mkProjStx (s : Syntax) (fieldName : Name) : Syntax :=
Syntax.node ``Lean.Parser.Term.proj #[s, mkAtomFrom s ".", mkIdentFrom s fieldName]
private def mkSubstructSource (structName : Name) (fieldNames : Array Name) (fieldName : Name) (src : Source) : TermElabM Source :=
match src with
| Source.explicit stx src => do
let idx ← getFieldIdx structName fieldNames fieldName
let stx := stx.modifyArg 0 fun stx => mkProjStx stx fieldName
return Source.explicit stx (mkProj structName idx src)
| s => return s
private def groupFields (expandStruct : Struct → TermElabM Struct) (s : Struct) : TermElabM Struct := do
let env ← getEnv
let fieldNames := getStructureFields env s.structName
withRef s.ref do
s.modifyFieldsM fun fields => do
let fieldMap ← mkFieldMap fields
fieldMap.toList.mapM fun ⟨fieldName, fields⟩ => do
match isSimpleField? fields with
| some field => pure field
| none =>
let substructFields := fields.map fun field => { field with lhs := field.lhs.tail! }
let substructSource ← mkSubstructSource s.structName fieldNames fieldName s.source
let field := fields.head!
match Lean.isSubobjectField? env s.structName fieldName with
| some substructName =>
let substruct := Struct.mk s.ref substructName substructFields substructSource
let substruct ← expandStruct substruct
pure { field with lhs := [field.lhs.head!], val := FieldVal.nested substruct }
| none => do
-- It is not a substructure field. Thus, we wrap fields using `Syntax`, and use `elabTerm` to process them.
let valStx := s.ref -- construct substructure syntax using s.ref as template
let valStx := valStx.setArg 4 mkNullNode -- erase optional expected type
let args := substructFields.toArray.map fun field => mkNullNode #[field.toSyntax, mkNullNode]
let valStx := valStx.setArg 2 (mkNullNode args)
let valStx := setStructSourceSyntax valStx substructSource
pure { field with lhs := [field.lhs.head!], val := FieldVal.term valStx }
def findField? (fields : Fields) (fieldName : Name) : Option (Field Struct) :=
fields.find? fun field =>
match field.lhs with
| [FieldLHS.fieldName _ n] => n == fieldName
| _ => false
private def addMissingFields (expandStruct : Struct → TermElabM Struct) (s : Struct) : TermElabM Struct := do
let env ← getEnv
let fieldNames := getStructureFields env s.structName
let ref := s.ref
withRef ref do
let fields ← fieldNames.foldlM (init := []) fun fields fieldName => do
match findField? s.fields fieldName with
| some field => return field::fields
| none =>
let addField (val : FieldVal Struct) : TermElabM Fields := do
return { ref := s.ref, lhs := [FieldLHS.fieldName s.ref fieldName], val := val } :: fields
match Lean.isSubobjectField? env s.structName fieldName with
| some substructName => do
let substructSource ← mkSubstructSource s.structName fieldNames fieldName s.source
let substruct := Struct.mk s.ref substructName [] substructSource
let substruct ← expandStruct substruct
addField (FieldVal.nested substruct)
| none =>
match s.source with
| Source.none => addField FieldVal.default
| Source.implicit _ => addField (FieldVal.term (mkHole s.ref))
| Source.explicit stx _ =>
-- stx is of the form `optional (try (termParser >> "with"))`
let src := stx[0]
let val := mkProjStx src fieldName
addField (FieldVal.term val)
return s.setFields fields.reverse
private partial def expandStruct (s : Struct) : TermElabM Struct := do
let s := expandCompositeFields s
let s ← expandNumLitFields s
let s ← expandParentFields s
let s ← groupFields expandStruct s
addMissingFields expandStruct s
structure CtorHeaderResult where
ctorFn : Expr
ctorFnType : Expr
instMVars : Array MVarId := #[]
private def mkCtorHeaderAux : Nat → Expr → Expr → Array MVarId → TermElabM CtorHeaderResult
| 0, type, ctorFn, instMVars => pure { ctorFn := ctorFn, ctorFnType := type, instMVars := instMVars }
| n+1, type, ctorFn, instMVars => do
let type ← whnfForall type
match type with
| Expr.forallE _ d b c =>
match c.binderInfo with
| BinderInfo.instImplicit =>
let a ← mkFreshExprMVar d MetavarKind.synthetic
mkCtorHeaderAux n (b.instantiate1 a) (mkApp ctorFn a) (instMVars.push a.mvarId!)
| _ =>
let a ← mkFreshExprMVar d
mkCtorHeaderAux n (b.instantiate1 a) (mkApp ctorFn a) instMVars
| _ => throwError "unexpected constructor type"
private partial def getForallBody : Nat → Expr → Option Expr
| i+1, Expr.forallE _ _ b _ => getForallBody i b
| i+1, _ => none
| 0, type => type
private def propagateExpectedType (type : Expr) (numFields : Nat) (expectedType? : Option Expr) : TermElabM Unit :=
match expectedType? with
| none => pure ()
| some expectedType => do
match getForallBody numFields type with
| none => pure ()
| some typeBody =>
unless typeBody.hasLooseBVars do
discard <| isDefEq expectedType typeBody
private def mkCtorHeader (ctorVal : ConstructorVal) (expectedType? : Option Expr) : TermElabM CtorHeaderResult := do
let us ← mkFreshLevelMVars ctorVal.levelParams.length
let val := Lean.mkConst ctorVal.name us
let type := (ConstantInfo.ctorInfo ctorVal).instantiateTypeLevelParams us
let r ← mkCtorHeaderAux ctorVal.numParams type val #[]
propagateExpectedType r.ctorFnType ctorVal.numFields expectedType?
synthesizeAppInstMVars r.instMVars
pure r
def markDefaultMissing (e : Expr) : Expr :=
mkAnnotation `structInstDefault e
def defaultMissing? (e : Expr) : Option Expr :=
annotation? `structInstDefault e
def throwFailedToElabField {α} (fieldName : Name) (structName : Name) (msgData : MessageData) : TermElabM α :=
throwError "failed to elaborate field '{fieldName}' of '{structName}, {msgData}"
def trySynthStructInstance? (s : Struct) (expectedType : Expr) : TermElabM (Option Expr) := do
if !s.allDefault then
pure none
else
try synthInstance? expectedType catch _ => pure none
private partial def elabStruct (s : Struct) (expectedType? : Option Expr) : TermElabM (Expr × Struct) := withRef s.ref do
let env ← getEnv
let ctorVal := getStructureCtor env s.structName
let { ctorFn := ctorFn, ctorFnType := ctorFnType, .. } ← mkCtorHeader ctorVal expectedType?
let (e, _, fields) ← s.fields.foldlM (init := (ctorFn, ctorFnType, [])) fun (e, type, fields) field =>
match field.lhs with
| [FieldLHS.fieldName ref fieldName] => do
let type ← whnfForall type
match type with
| Expr.forallE _ d b c =>
let cont (val : Expr) (field : Field Struct) : TermElabM (Expr × Expr × Fields) := do
pushInfoTree <| InfoTree.node (children := {}) <| Info.ofFieldInfo { lctx := (← getLCtx), val := val, name := fieldName, stx := ref }
let e := mkApp e val
let type := b.instantiate1 val
let field := { field with expr? := some val }
pure (e, type, field::fields)
match field.val with
| FieldVal.term stx => cont (← elabTermEnsuringType stx d) field
| FieldVal.nested s => do
-- if all fields of `s` are marked as `default`, then try to synthesize instance
match (← trySynthStructInstance? s d) with
| some val => cont val { field with val := FieldVal.term (mkHole field.ref) }
| none => do let (val, sNew) ← elabStruct s (some d); let val ← ensureHasType d val; cont val { field with val := FieldVal.nested sNew }
| FieldVal.default => do let val ← withRef field.ref <| mkFreshExprMVar (some d); cont (markDefaultMissing val) field
| _ => withRef field.ref <| throwFailedToElabField fieldName s.structName m!"unexpected constructor type{indentExpr type}"
| _ => throwErrorAt field.ref "unexpected unexpanded structure field"
pure (e, s.setFields fields.reverse)
namespace DefaultFields
structure Context where
-- We must search for default values overriden in derived structures
structs : Array Struct := #[]
allStructNames : Array Name := #[]
/--
Consider the following example:
```
structure A where
x : Nat := 1
structure B extends A where
y : Nat := x + 1
x := y + 1
structure C extends B where
z : Nat := 2*y
x := z + 3
```
And we are trying to elaborate a structure instance for `C`. There are default values for `x` at `A`, `B`, and `C`.
We say the default value at `C` has distance 0, the one at `B` distance 1, and the one at `A` distance 2.
The field `maxDistance` specifies the maximum distance considered in a round of Default field computation.
Remark: since `C` does not set a default value of `y`, the default value at `B` is at distance 0.
The fixpoint for setting default values works in the following way.
- Keep computing default values using `maxDistance == 0`.
- We increase `maxDistance` whenever we failed to compute a new default value in a round.
- If `maxDistance > 0`, then we interrupt a round as soon as we compute some default value.
We use depth-first search.
- We sign an error if no progress is made when `maxDistance` == structure hierarchy depth (2 in the example above).
-/
maxDistance : Nat := 0
structure State where
progress : Bool := false
partial def collectStructNames (struct : Struct) (names : Array Name) : Array Name :=
let names := names.push struct.structName
struct.fields.foldl (init := names) fun names field =>
match field.val with
| FieldVal.nested struct => collectStructNames struct names
| _ => names
partial def getHierarchyDepth (struct : Struct) : Nat :=
struct.fields.foldl (init := 0) fun max field =>
match field.val with
| FieldVal.nested struct => Nat.max max (getHierarchyDepth struct + 1)
| _ => max
partial def findDefaultMissing? (mctx : MetavarContext) (struct : Struct) : Option (Field Struct) :=
struct.fields.findSome? fun field =>
match field.val with
| FieldVal.nested struct => findDefaultMissing? mctx struct
| _ => match field.expr? with
| none => unreachable!
| some expr => match defaultMissing? expr with
| some (Expr.mvar mvarId _) => if mctx.isExprAssigned mvarId then none else some field
| _ => none
def getFieldName (field : Field Struct) : Name :=
match field.lhs with
| [FieldLHS.fieldName _ fieldName] => fieldName
| _ => unreachable!
abbrev M := ReaderT Context (StateRefT State TermElabM)
def isRoundDone : M Bool := do
return (← get).progress && (← read).maxDistance > 0
def getFieldValue? (struct : Struct) (fieldName : Name) : Option Expr :=
struct.fields.findSome? fun field =>
if getFieldName field == fieldName then
field.expr?
else
none
partial def mkDefaultValueAux? (struct : Struct) : Expr → TermElabM (Option Expr)
| Expr.lam n d b c => withRef struct.ref do
if c.binderInfo.isExplicit then
let fieldName := n
match getFieldValue? struct fieldName with
| none => pure none
| some val =>
let valType ← inferType val
if (← isDefEq valType d) then
mkDefaultValueAux? struct (b.instantiate1 val)
else
pure none
else
let arg ← mkFreshExprMVar d
mkDefaultValueAux? struct (b.instantiate1 arg)
| e =>
if e.isAppOfArity ``id 2 then
pure (some e.appArg!)
else
pure (some e)
def mkDefaultValue? (struct : Struct) (cinfo : ConstantInfo) : TermElabM (Option Expr) :=
withRef struct.ref do
let us ← mkFreshLevelMVarsFor cinfo
mkDefaultValueAux? struct (cinfo.instantiateValueLevelParams us)
/-- If `e` is a projection function of one of the given structures, then reduce it -/
def reduceProjOf? (structNames : Array Name) (e : Expr) : MetaM (Option Expr) := do
if !e.isApp then pure none
else match e.getAppFn with
| Expr.const name _ _ => do
let env ← getEnv
match env.getProjectionStructureName? name with
| some structName =>
if structNames.contains structName then
Meta.unfoldDefinition? e
else
pure none
| none => pure none
| _ => pure none
/-- Reduce default value. It performs beta reduction and projections of the given structures. -/
partial def reduce (structNames : Array Name) : Expr → MetaM Expr
| e@(Expr.lam _ _ _ _) => lambdaLetTelescope e fun xs b => do mkLambdaFVars xs (← reduce structNames b)
| e@(Expr.forallE _ _ _ _) => forallTelescope e fun xs b => do mkForallFVars xs (← reduce structNames b)
| e@(Expr.letE _ _ _ _ _) => lambdaLetTelescope e fun xs b => do mkLetFVars xs (← reduce structNames b)
| e@(Expr.proj _ i b _) => do
match (← Meta.project? b i) with
| some r => reduce structNames r
| none => return e.updateProj! (← reduce structNames b)
| e@(Expr.app f _ _) => do
match (← reduceProjOf? structNames e) with
| some r => reduce structNames r
| none =>
let f := f.getAppFn
let f' ← reduce structNames f
if f'.isLambda then
let revArgs := e.getAppRevArgs
reduce structNames (f'.betaRev revArgs)
else
let args ← e.getAppArgs.mapM (reduce structNames)
return (mkAppN f' args)
| e@(Expr.mdata _ b _) => do
let b ← reduce structNames b
if (defaultMissing? e).isSome && !b.isMVar then
return b
else
return e.updateMData! b
| e@(Expr.mvar mvarId _) => do
match (← getExprMVarAssignment? mvarId) with
| some val => if val.isMVar then reduce structNames val else pure val
| none => return e
| e => return e
partial def tryToSynthesizeDefault (structs : Array Struct) (allStructNames : Array Name) (maxDistance : Nat) (fieldName : Name) (mvarId : MVarId) : TermElabM Bool :=
let rec loop (i : Nat) (dist : Nat) := do
if dist > maxDistance then
pure false
else if h : i < structs.size then do
let struct := structs.get ⟨i, h⟩
let defaultName := struct.structName ++ fieldName ++ `_default
let env ← getEnv
match env.find? defaultName with
| some cinfo@(ConstantInfo.defnInfo defVal) => do
let mctx ← getMCtx
let val? ← mkDefaultValue? struct cinfo
match val? with
| none => do setMCtx mctx; loop (i+1) (dist+1)
| some val => do
let val ← reduce allStructNames val
match val.find? fun e => (defaultMissing? e).isSome with
| some _ => setMCtx mctx; loop (i+1) (dist+1)
| none =>
let mvarDecl ← getMVarDecl mvarId
let val ← ensureHasType mvarDecl.type val
assignExprMVar mvarId val
pure true
| _ => loop (i+1) dist
else
pure false
loop 0 0
partial def step (struct : Struct) : M Unit :=
unless (← isRoundDone) do
withReader (fun ctx => { ctx with structs := ctx.structs.push struct }) do
for field in struct.fields do
match field.val with
| FieldVal.nested struct => step struct
| _ => match field.expr? with
| none => unreachable!
| some expr => match defaultMissing? expr with
| some (Expr.mvar mvarId _) =>
unless (← isExprMVarAssigned mvarId) do
let ctx ← read
if (← withRef field.ref <| tryToSynthesizeDefault ctx.structs ctx.allStructNames ctx.maxDistance (getFieldName field) mvarId) then
modify fun s => { s with progress := true }
| _ => pure ()
partial def propagateLoop (hierarchyDepth : Nat) (d : Nat) (struct : Struct) : M Unit := do
match findDefaultMissing? (← getMCtx) struct with
| none => pure () -- Done
| some field =>
if d > hierarchyDepth then
throwErrorAt field.ref "field '{getFieldName field}' is missing"
else withReader (fun ctx => { ctx with maxDistance := d }) do
modify fun s => { s with progress := false }
step struct
if (← get).progress then do
propagateLoop hierarchyDepth 0 struct
else
propagateLoop hierarchyDepth (d+1) struct
def propagate (struct : Struct) : TermElabM Unit :=
let hierarchyDepth := getHierarchyDepth struct
let structNames := collectStructNames struct #[]
(propagateLoop hierarchyDepth 0 struct { allStructNames := structNames }).run' {}
end DefaultFields
private def elabStructInstAux (stx : Syntax) (expectedType? : Option Expr) (source : Source) : TermElabM Expr := do
let (structName, structType) ← getStructName stx expectedType? source
unless isStructureLike (← getEnv) structName do
throwError "invalid \{...} notation, structure type expected{indentExpr structType}"
let struct ← liftMacroM <| mkStructView stx structName source
let struct ← expandStruct struct
trace[Elab.struct] "{struct}"
let (r, struct) ← elabStruct struct expectedType?
DefaultFields.propagate struct
return r
@[builtinTermElab structInst] def elabStructInst : TermElab := fun stx expectedType? => do
match (← expandNonAtomicExplicitSource stx) with
| some stxNew => withMacroExpansion stx stxNew <| elabTerm stxNew expectedType?
| none =>
let sourceView ← getStructSource stx
match (← isModifyOp? stx), sourceView with
| some modifyOp, Source.explicit source _ => elabModifyOp stx modifyOp source expectedType?
| some _, _ => throwError "invalid \{...} notation, explicit source is required when using '[<index>] := <value>'"
| _, _ => elabStructInstAux stx expectedType? sourceView
builtin_initialize registerTraceClass `Elab.struct
end Lean.Elab.Term.StructInst
|
385321be13c279435aebb5f404d26b98d1a5f194 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/algebra/monoid_algebra/to_direct_sum.lean | 4f43e85416d37758d71dee7685109c3583d755cb | [
"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 | 7,819 | 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 algebra.direct_sum.algebra
import algebra.monoid_algebra.basic
import data.finsupp.to_dfinsupp
/-!
# Conversion between `add_monoid_algebra` and homogenous `direct_sum`
This module provides conversions between `add_monoid_algebra` and `direct_sum`.
The latter is essentially a dependent version of the former.
Note that since `direct_sum.has_mul` combines indices additively, there is no equivalent to
`monoid_algebra`.
## Main definitions
* `add_monoid_algebra.to_direct_sum : add_monoid_algebra M ι → (⨁ i : ι, M)`
* `direct_sum.to_add_monoid_algebra : (⨁ i : ι, M) → add_monoid_algebra M ι`
* Bundled equiv versions of the above:
* `add_monoid_algebra_equiv_direct_sum : add_monoid_algebra M ι ≃ (⨁ i : ι, M)`
* `add_monoid_algebra_add_equiv_direct_sum : add_monoid_algebra M ι ≃+ (⨁ i : ι, M)`
* `add_monoid_algebra_ring_equiv_direct_sum R : add_monoid_algebra M ι ≃+* (⨁ i : ι, M)`
* `add_monoid_algebra_alg_equiv_direct_sum R : add_monoid_algebra A ι ≃ₐ[R] (⨁ i : ι, A)`
## Theorems
The defining feature of these operations is that they map `finsupp.single` to
`direct_sum.of` and vice versa:
* `add_monoid_algebra.to_direct_sum_single`
* `direct_sum.to_add_monoid_algebra_of`
as well as preserving arithmetic operations.
For the bundled equivalences, we provide lemmas that they reduce to
`add_monoid_algebra.to_direct_sum`:
* `add_monoid_algebra_add_equiv_direct_sum_apply`
* `add_monoid_algebra_lequiv_direct_sum_apply`
* `add_monoid_algebra_add_equiv_direct_sum_symm_apply`
* `add_monoid_algebra_lequiv_direct_sum_symm_apply`
## Implementation notes
This file largely just copies the API of `data/finsupp/to_dfinsupp`, and reuses the proofs.
Recall that `add_monoid_algebra M ι` is defeq to `ι →₀ M` and `⨁ i : ι, M` is defeq to
`Π₀ i : ι, M`.
Note that there is no `add_monoid_algebra` equivalent to `finsupp.single`, so many statements
still involve this definition.
-/
variables {ι : Type*} {R : Type*} {M : Type*} {A : Type*}
open_locale direct_sum
/-! ### Basic definitions and lemmas -/
section defs
/-- Interpret a `add_monoid_algebra` as a homogenous `direct_sum`. -/
def add_monoid_algebra.to_direct_sum [semiring M] (f : add_monoid_algebra M ι) : ⨁ i : ι, M :=
finsupp.to_dfinsupp f
section
variables [decidable_eq ι] [semiring M]
@[simp] lemma add_monoid_algebra.to_direct_sum_single (i : ι) (m : M) :
add_monoid_algebra.to_direct_sum (finsupp.single i m) = direct_sum.of _ i m :=
finsupp.to_dfinsupp_single i m
variables [Π m : M, decidable (m ≠ 0)]
/-- Interpret a homogenous `direct_sum` as a `add_monoid_algebra`. -/
def direct_sum.to_add_monoid_algebra (f : ⨁ i : ι, M) :
add_monoid_algebra M ι :=
dfinsupp.to_finsupp f
@[simp] lemma direct_sum.to_add_monoid_algebra_of (i : ι) (m : M) :
(direct_sum.of _ i m : ⨁ i : ι, M).to_add_monoid_algebra = finsupp.single i m :=
dfinsupp.to_finsupp_single i m
@[simp] lemma add_monoid_algebra.to_direct_sum_to_add_monoid_algebra (f : add_monoid_algebra M ι) :
f.to_direct_sum.to_add_monoid_algebra = f :=
finsupp.to_dfinsupp_to_finsupp f
@[simp] lemma direct_sum.to_add_monoid_algebra_to_direct_sum (f : ⨁ i : ι, M) :
f.to_add_monoid_algebra.to_direct_sum = f :=
dfinsupp.to_finsupp_to_dfinsupp f
end
end defs
/-! ### Lemmas about arithmetic operations -/
section lemmas
namespace add_monoid_algebra
@[simp] lemma to_direct_sum_zero [semiring M] :
(0 : add_monoid_algebra M ι).to_direct_sum = 0 := finsupp.to_dfinsupp_zero
@[simp] lemma to_direct_sum_add [semiring M] (f g : add_monoid_algebra M ι) :
(f + g).to_direct_sum = f.to_direct_sum + g.to_direct_sum := finsupp.to_dfinsupp_add _ _
@[simp] lemma to_direct_sum_mul [decidable_eq ι] [add_monoid ι] [semiring M]
(f g : add_monoid_algebra M ι) :
(f * g).to_direct_sum = f.to_direct_sum * g.to_direct_sum :=
begin
let to_hom : add_monoid_algebra M ι →+ (⨁ i : ι, M) :=
⟨to_direct_sum, to_direct_sum_zero, to_direct_sum_add⟩,
show to_hom (f * g) = to_hom f * to_hom g,
revert f g,
rw add_monoid_hom.map_mul_iff,
ext xi xv yi yv : 4,
dsimp only [add_monoid_hom.comp_apply, add_monoid_hom.compl₂_apply,
add_monoid_hom.compr₂_apply, add_monoid_hom.mul_apply, add_equiv.coe_to_add_monoid_hom,
finsupp.single_add_hom_apply],
simp only [add_monoid_algebra.single_mul_single, to_hom, add_monoid_hom.coe_mk,
add_monoid_algebra.to_direct_sum_single, direct_sum.of_mul_of, has_mul.ghas_mul_mul]
end
end add_monoid_algebra
namespace direct_sum
variables [decidable_eq ι]
@[simp] lemma to_add_monoid_algebra_zero [semiring M] [Π m : M, decidable (m ≠ 0)] :
to_add_monoid_algebra 0 = (0 : add_monoid_algebra M ι) := dfinsupp.to_finsupp_zero
@[simp] lemma to_add_monoid_algebra_add [semiring M] [Π m : M, decidable (m ≠ 0)]
(f g : ⨁ i : ι, M) :
(f + g).to_add_monoid_algebra = to_add_monoid_algebra f + to_add_monoid_algebra g :=
dfinsupp.to_finsupp_add _ _
@[simp] lemma to_add_monoid_algebra_mul [add_monoid ι] [semiring M] [Π m : M, decidable (m ≠ 0)]
(f g : ⨁ i : ι, M) :
(f * g).to_add_monoid_algebra = to_add_monoid_algebra f * to_add_monoid_algebra g :=
begin
apply_fun add_monoid_algebra.to_direct_sum,
{ simp },
{ apply function.left_inverse.injective,
apply add_monoid_algebra.to_direct_sum_to_add_monoid_algebra }
end
end direct_sum
end lemmas
/-! ### Bundled `equiv`s -/
section equivs
/-- `add_monoid_algebra.to_direct_sum` and `direct_sum.to_add_monoid_algebra` together form an
equiv. -/
@[simps {fully_applied := ff}]
def add_monoid_algebra_equiv_direct_sum [decidable_eq ι] [semiring M] [Π m : M, decidable (m ≠ 0)] :
add_monoid_algebra M ι ≃ (⨁ i : ι, M) :=
{ to_fun := add_monoid_algebra.to_direct_sum, inv_fun := direct_sum.to_add_monoid_algebra,
..finsupp_equiv_dfinsupp }
/-- The additive version of `add_monoid_algebra.to_add_monoid_algebra`. Note that this is
`noncomputable` because `add_monoid_algebra.has_add` is noncomputable. -/
@[simps {fully_applied := ff}]
def add_monoid_algebra_add_equiv_direct_sum
[decidable_eq ι] [semiring M] [Π m : M, decidable (m ≠ 0)] :
add_monoid_algebra M ι ≃+ (⨁ i : ι, M) :=
{ to_fun := add_monoid_algebra.to_direct_sum, inv_fun := direct_sum.to_add_monoid_algebra,
map_add' := add_monoid_algebra.to_direct_sum_add,
.. add_monoid_algebra_equiv_direct_sum}
/-- The ring version of `add_monoid_algebra.to_add_monoid_algebra`. Note that this is
`noncomputable` because `add_monoid_algebra.has_add` is noncomputable. -/
@[simps {fully_applied := ff}]
def add_monoid_algebra_ring_equiv_direct_sum
[decidable_eq ι] [add_monoid ι] [semiring M]
[Π m : M, decidable (m ≠ 0)] :
add_monoid_algebra M ι ≃+* ⨁ i : ι, M :=
{ to_fun := add_monoid_algebra.to_direct_sum, inv_fun := direct_sum.to_add_monoid_algebra,
map_mul' := add_monoid_algebra.to_direct_sum_mul,
..(add_monoid_algebra_add_equiv_direct_sum : add_monoid_algebra M ι ≃+ ⨁ i : ι, M) }
/-- The algebra version of `add_monoid_algebra.to_add_monoid_algebra`. Note that this is
`noncomputable` because `add_monoid_algebra.has_add` is noncomputable. -/
@[simps {fully_applied := ff}]
def add_monoid_algebra_alg_equiv_direct_sum
[decidable_eq ι] [add_monoid ι] [comm_semiring R] [semiring A] [algebra R A]
[Π m : A, decidable (m ≠ 0)] :
add_monoid_algebra A ι ≃ₐ[R] ⨁ i : ι, A :=
{ to_fun := add_monoid_algebra.to_direct_sum, inv_fun := direct_sum.to_add_monoid_algebra,
commutes' := λ r, add_monoid_algebra.to_direct_sum_single _ _,
..(add_monoid_algebra_ring_equiv_direct_sum : add_monoid_algebra A ι ≃+* ⨁ i : ι, A) }
end equivs
|
3d5c670aa9951028138db8977a932a4dd0deb002 | 46125763b4dbf50619e8846a1371029346f4c3db | /src/tactic/rename.lean | 2da46f18948740be56ed1dd8ca70daaae7a136c3 | [
"Apache-2.0"
] | permissive | thjread/mathlib | a9d97612cedc2c3101060737233df15abcdb9eb1 | 7cffe2520a5518bba19227a107078d83fa725ddc | refs/heads/master | 1,615,637,696,376 | 1,583,953,063,000 | 1,583,953,063,000 | 246,680,271 | 0 | 0 | Apache-2.0 | 1,583,960,875,000 | 1,583,960,875,000 | null | UTF-8 | Lean | false | false | 3,511 | lean | /-
Copyright (c) 2020 Jannis Limperg. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Jannis Limperg
-/
import tactic.core
/-!
# Better `rename` tactic
This module defines a variant of the standard `rename` tactic, with the
following improvements:
* You can rename multiple hypotheses at the same time.
* Renaming a hypothesis does not change its location in the context.
-/
open lean lean.parser interactive native
namespace tactic
/-- Get the revertible part of the local context. These are the hypotheses that
appear after the last frozen local instance in the local context. We call them
revertible because `revert` can revert them, unlike those hypotheses which occur
before a frozen instance. -/
meta def revertible_local_context : tactic (list expr) := do
ctx ← local_context,
frozen ← frozen_local_instances,
pure $
match frozen with
| none := ctx
| some [] := ctx
| some (h :: _) := ctx.after (eq h)
end
/-- Rename local hypotheses according to the given `name_map`. The `name_map`
contains as keys those hypotheses that should be renamed; the associated values
are the new names.
This tactic can only rename hypotheses which occur after the last frozen local
instance. If you need to rename earlier hypotheses, try
`unfreeze_local_instances`.
If `strict` is true, we fail if `name_map` refers to hypotheses that do not
appear in the local context or that appear before a frozen local instance.
Conversely, if `strict` is false, some entries of `name_map` may be silently
ignored.
Note that we allow shadowing, so renamed hypotheses may have the same name
as other hypotheses in the context.
-/
meta def rename' (renames : name_map name) (strict := tt) : tactic unit := do
ctx ← revertible_local_context,
when strict (do
let ctx_names := rb_map.set_of_list (ctx.map expr.local_pp_name),
let invalid_renames :=
(renames.to_list.map prod.fst).filter (λ h, ¬ ctx_names.contains h),
when ¬ invalid_renames.empty $ fail $ format.join
[ "Cannot rename these hypotheses:\n"
, format.intercalate ", " (invalid_renames.map to_fmt)
, format.line
, "This is because these hypotheses either do not occur in the\n"
, "context or they occur before a frozen local instance.\n"
, "In the latter case, try `tactic.unfreeze_local_instances`."
]),
let new_name := λ current_name,
(renames.find current_name).get_or_else current_name,
let intro_names := list.map (new_name ∘ expr.local_pp_name) ctx,
revert_lst ctx,
intro_lst intro_names,
pure ()
end tactic
namespace tactic.interactive
/-- Parse a current name and new name for `rename'`. -/
meta def rename'_arg_parser : parser (name × name) :=
prod.mk <$> ident <*> (optional (tk "->") *> ident)
/-- Parse the arguments of `rename'`. -/
meta def rename'_args_parser : parser (list (name × name)) :=
(functor.map (λ x, [x]) rename'_arg_parser)
<|>
(tk "[" *> sep_by (tk ",") rename'_arg_parser <* tk "]")
/--
Rename one or more local hypotheses. The renamings are given as follows:
```
rename' x y -- rename x to y
rename' x → y -- ditto
rename' [x y, a b] -- rename x to y and a to b
rename' [x → y, a → b] -- ditto
```
Brackets are necessary if multiple hypotheses should be renamed in parallel.
-/
meta def rename' (renames : parse rename'_args_parser) : tactic unit :=
tactic.rename' (rb_map.of_list renames)
end tactic.interactive
|
49a0d16d8ef1e2cd7a91ffd2e0829e4983ebf483 | a9fe717b93ccfa4b2e64faeb24f96dfefb390240 | /int/main.lean | a57994b6489dd7ea218e05bd5031cd4aed5ffd91 | [] | no_license | skbaek/omega | ab1f4a6daadfc8c855f14c39d9459ab841527141 | 715e384ed14e8eb177a326700066e7c98269e078 | refs/heads/master | 1,588,000,876,352 | 1,552,645,917,000 | 1,552,645,917,000 | 174,442,914 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 1,109 | lean | import algebra.group order.basic ..logic
.rev .form .dnf .reify ..expr_of_unsat
namespace int
open tactic
run_cmd mk_simp_attr `sugar
attribute [sugar]
not_le not_lt
int.lt_iff_add_one_le
or_false false_or
and_true true_and
ge gt mul_add add_mul
mul_comm sub_eq_add_neg
classical.imp_iff_not_or
classical.iff_iff
meta def desugar := `[try {simp only with sugar}]
lemma uniclo_of_unsat_clausify (m : nat) (p : form) :
clauses.unsat (dnf (¬*p)) → uniclo p (λ x, 0) m | h1 :=
begin
apply uniclo_of_valid,
apply valid_of_unsat_not,
apply unsat_of_clauses_unsat,
exact h1
end
/- Given a p : form, return the expr of a term t : p.uniclo -/
meta def expr_of_uniclo (m : nat) (p : form) : tactic expr :=
do x ← expr_of_unsats (dnf (¬*p)),
return `(uniclo_of_unsat_clausify %%`(m) %%`(p) %%x)
--meta def expr_of_lia : tactic expr :=
--target >>= to_form >>= expr_of_uniclo
meta def expr_of_lia : tactic expr :=
do (p,m) ← target >>= to_form 0,
expr_of_uniclo m p
meta def omega : tactic unit :=
do rev, desugar,
expr_of_lia >>= apply,
skip
end int |
f9662f575dc7e6a399d0136aefb78971bf1928ae | 94e33a31faa76775069b071adea97e86e218a8ee | /src/category_theory/limits/shapes/comm_sq.lean | 30d7bc3df50ec6e85aaf290f15d03484b864920a | [
"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 | 19,813 | 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.preserves.shapes.pullbacks
import category_theory.limits.shapes.zero_morphisms
import category_theory.limits.constructions.binary_products
/-!
# Pullback and pushout squares
We provide another API for pullbacks and pushouts.
`is_pullback fst snd f g` is the proposition that
```
P --fst--> X
| |
snd f
| |
v v
Y ---g---> Z
```
is a pullback square.
(And similarly for `is_pushout`.)
We provide the glue to go back and forth to the usual `is_limit` API for pullbacks, and prove
`is_pullback (pullback.fst : pullback f g ⟶ X) (pullback.snd : pullback f g ⟶ Y) f g`
for the usual `pullback f g` provided by the `has_limit` API.
We don't attempt to restate everything we know about pullbacks in this language,
but do restate the pasting lemmas.
## Future work
Bicartesian squares, and
show that the pullback and pushout squares for a biproduct are bicartesian.
-/
noncomputable theory
open category_theory
open category_theory.limits
universes v₁ v₂ u₁ u₂
namespace category_theory
variables {C : Type u₁} [category.{v₁} C]
/-- The proposition that a square
```
W ---f---> X
| |
g h
| |
v v
Y ---i---> Z
```
is a commuting square.
-/
structure comm_sq {W X Y Z : C} (f : W ⟶ X) (g : W ⟶ Y) (h : X ⟶ Z) (i : Y ⟶ Z) : Prop :=
(w : f ≫ h = g ≫ i)
attribute [reassoc] comm_sq.w
namespace comm_sq
variables {W X Y Z : C} {f : W ⟶ X} {g : W ⟶ Y} {h : X ⟶ Z} {i : Y ⟶ Z}
lemma flip (p : comm_sq f g h i) : comm_sq g f i h := ⟨p.w.symm⟩
lemma of_arrow {f g : arrow C} (h : f ⟶ g) : comm_sq f.hom h.left h.right g.hom := ⟨h.w.symm⟩
/--
The (not necessarily limiting) `pullback_cone h i` implicit in the statement
that we have `comm_sq f g h i`.
-/
def cone (s : comm_sq f g h i) : pullback_cone h i := pullback_cone.mk _ _ s.w
/--
The (not necessarily limiting) `pushout_cocone f g` implicit in the statement
that we have `comm_sq f g h i`.
-/
def cocone (s : comm_sq f g h i) : pushout_cocone f g := pushout_cocone.mk _ _ s.w
end comm_sq
/-- The proposition that a square
```
P --fst--> X
| |
snd f
| |
v v
Y ---g---> Z
```
is a pullback square.
-/
structure is_pullback
{P X Y Z : C} (fst : P ⟶ X) (snd : P ⟶ Y) (f : X ⟶ Z) (g : Y ⟶ Z)
extends comm_sq fst snd f g : Prop :=
(is_limit' : nonempty (is_limit (pullback_cone.mk _ _ w)))
/-- The proposition that a square
```
Z ---f---> X
| |
g inl
| |
v v
Y --inr--> P
```
is a pushout square.
-/
structure is_pushout
{Z X Y P : C} (f : Z ⟶ X) (g : Z ⟶ Y) (inl : X ⟶ P) (inr : Y ⟶ P)
extends comm_sq f g inl inr : Prop :=
(is_colimit' : nonempty (is_colimit (pushout_cocone.mk _ _ w)))
/-!
We begin by providing some glue between `is_pullback` and the `is_limit` and `has_limit` APIs.
(And similarly for `is_pushout`.)
-/
namespace is_pullback
variables {P X Y Z : C} {fst : P ⟶ X} {snd : P ⟶ Y} {f : X ⟶ Z} {g : Y ⟶ Z}
/--
The (limiting) `pullback_cone f g` implicit in the statement
that we have a `is_pullback fst snd f g`.
-/
def cone (h : is_pullback fst snd f g) : pullback_cone f g := h.to_comm_sq.cone
/--
The cone obtained from `is_pullback fst snd f g` is a limit cone.
-/
noncomputable def is_limit (h : is_pullback fst snd f g) : is_limit h.cone :=
h.is_limit'.some
/-- If `c` is a limiting pullback cone, then we have a `is_pullback c.fst c.snd f g`. -/
lemma of_is_limit {c : pullback_cone f g} (h : limits.is_limit c) :
is_pullback c.fst c.snd f g :=
{ w := c.condition,
is_limit' := ⟨is_limit.of_iso_limit h
(limits.pullback_cone.ext (iso.refl _) (by tidy) (by tidy))⟩, }
/-- A variant of `of_is_limit` that is more useful with `apply`. -/
lemma of_is_limit' (w : comm_sq fst snd f g) (h : limits.is_limit w.cone) :
is_pullback fst snd f g :=
of_is_limit h
/-- The pullback provided by `has_pullback f g` fits into a `is_pullback`. -/
lemma of_has_pullback (f : X ⟶ Z) (g : Y ⟶ Z) [has_pullback f g] :
is_pullback (pullback.fst : pullback f g ⟶ X) (pullback.snd : pullback f g ⟶ Y) f g :=
of_is_limit (limit.is_limit (cospan f g))
/-- If `c` is a limiting binary product cone, and we have a terminal object,
then we have `is_pullback c.fst c.snd 0 0`
(where each `0` is the unique morphism to the terminal object). -/
lemma of_is_product {c : binary_fan X Y} (h : limits.is_limit c) (t : is_terminal Z) :
is_pullback c.fst c.snd (t.from _) (t.from _) :=
of_is_limit (is_pullback_of_is_terminal_is_product _ _ _ _ t
(is_limit.of_iso_limit h (limits.cones.ext (iso.refl c.X) (by rintro ⟨⟨⟩⟩; { dsimp, simp, }))))
variables (X Y)
lemma of_has_binary_product' [has_binary_product X Y] [has_terminal C] :
is_pullback limits.prod.fst limits.prod.snd (terminal.from X) (terminal.from Y) :=
of_is_product (limit.is_limit _) terminal_is_terminal
open_locale zero_object
lemma of_has_binary_product [has_binary_product X Y] [has_zero_object C] [has_zero_morphisms C] :
is_pullback limits.prod.fst limits.prod.snd (0 : X ⟶ 0) (0 : Y ⟶ 0) :=
by convert of_is_product (limit.is_limit _) has_zero_object.zero_is_terminal
variables {X Y}
/-- Any object at the top left of a pullback square is
isomorphic to the pullback provided by the `has_limit` API. -/
noncomputable
def iso_pullback (h : is_pullback fst snd f g) [has_pullback f g] : P ≅ pullback f g :=
(limit.iso_limit_cone ⟨_, h.is_limit⟩).symm
@[simp] lemma iso_pullback_hom_fst (h : is_pullback fst snd f g) [has_pullback f g] :
h.iso_pullback.hom ≫ pullback.fst = fst :=
by { dsimp [iso_pullback, cone, comm_sq.cone], simp, }
@[simp] lemma iso_pullback_hom_snd (h : is_pullback fst snd f g) [has_pullback f g] :
h.iso_pullback.hom ≫ pullback.snd = snd :=
by { dsimp [iso_pullback, cone, comm_sq.cone], simp, }
@[simp] lemma iso_pullback_inv_fst (h : is_pullback fst snd f g) [has_pullback f g] :
h.iso_pullback.inv ≫ fst = pullback.fst :=
by simp [iso.inv_comp_eq]
@[simp] lemma iso_pullback_inv_snd (h : is_pullback fst snd f g) [has_pullback f g] :
h.iso_pullback.inv ≫ snd = pullback.snd :=
by simp [iso.inv_comp_eq]
lemma of_iso_pullback (h : comm_sq fst snd f g) [has_pullback f g] (i : P ≅ pullback f g)
(w₁ : i.hom ≫ pullback.fst = fst) (w₂ : i.hom ≫ pullback.snd = snd) : is_pullback fst snd f g :=
of_is_limit' h (limits.is_limit.of_iso_limit (limit.is_limit _)
(@pullback_cone.ext _ _ _ _ _ _ _ (pullback_cone.mk _ _ _) _ i w₁.symm w₂.symm).symm)
end is_pullback
namespace is_pushout
variables {Z X Y P : C} {f : Z ⟶ X} {g : Z ⟶ Y} {inl : X ⟶ P} {inr : Y ⟶ P}
/--
The (colimiting) `pushout_cocone f g` implicit in the statement
that we have a `is_pushout f g inl inr`.
-/
def cocone (h : is_pushout f g inl inr) : pushout_cocone f g := h.to_comm_sq.cocone
/--
The cocone obtained from `is_pushout f g inl inr` is a colimit cocone.
-/
noncomputable def is_colimit (h : is_pushout f g inl inr) : is_colimit h.cocone :=
h.is_colimit'.some
/-- If `c` is a colimiting pushout cocone, then we have a `is_pushout f g c.inl c.inr`. -/
lemma of_is_colimit {c : pushout_cocone f g} (h : limits.is_colimit c) :
is_pushout f g c.inl c.inr :=
{ w := c.condition,
is_colimit' := ⟨is_colimit.of_iso_colimit h
(limits.pushout_cocone.ext (iso.refl _) (by tidy) (by tidy))⟩, }
/-- A variant of `of_is_colimit` that is more useful with `apply`. -/
lemma of_is_colimit' (w : comm_sq f g inl inr) (h : limits.is_colimit w.cocone) :
is_pushout f g inl inr :=
of_is_colimit h
/-- The pushout provided by `has_pushout f g` fits into a `is_pushout`. -/
lemma of_has_pushout (f : Z ⟶ X) (g : Z ⟶ Y) [has_pushout f g] :
is_pushout f g (pushout.inl : X ⟶ pushout f g) (pushout.inr : Y ⟶ pushout f g) :=
of_is_colimit (colimit.is_colimit (span f g))
/-- If `c` is a colimiting binary coproduct cocone, and we have an initial object,
then we have `is_pushout 0 0 c.inl c.inr`
(where each `0` is the unique morphism from the initial object). -/
lemma of_is_coproduct {c : binary_cofan X Y} (h : limits.is_colimit c) (t : is_initial Z) :
is_pushout (t.to _) (t.to _) c.inl c.inr :=
of_is_colimit (is_pushout_of_is_initial_is_coproduct _ _ _ _ t
(is_colimit.of_iso_colimit h
(limits.cocones.ext (iso.refl c.X) (by rintro ⟨⟨⟩⟩; { dsimp, simp, }))))
variables (X Y)
lemma of_has_binary_coproduct' [has_binary_coproduct X Y] [has_initial C] :
is_pushout (initial.to _) (initial.to _) (coprod.inl : X ⟶ _) (coprod.inr : Y ⟶ _) :=
of_is_coproduct (colimit.is_colimit _) initial_is_initial
open_locale zero_object
lemma of_has_binary_coproduct
[has_binary_coproduct X Y] [has_zero_object C] [has_zero_morphisms C] :
is_pushout (0 : 0 ⟶ X) (0 : 0 ⟶ Y) coprod.inl coprod.inr :=
by convert of_is_coproduct (colimit.is_colimit _) has_zero_object.zero_is_initial
variables {X Y}
/-- Any object at the top left of a pullback square is
isomorphic to the pullback provided by the `has_limit` API. -/
noncomputable
def iso_pushout (h : is_pushout f g inl inr) [has_pushout f g] : P ≅ pushout f g :=
(colimit.iso_colimit_cocone ⟨_, h.is_colimit⟩).symm
@[simp] lemma inl_iso_pushout_inv (h : is_pushout f g inl inr) [has_pushout f g] :
pushout.inl ≫ h.iso_pushout.inv = inl :=
by { dsimp [iso_pushout, cocone, comm_sq.cocone], simp, }
@[simp] lemma inr_iso_pushout_inv (h : is_pushout f g inl inr) [has_pushout f g] :
pushout.inr ≫ h.iso_pushout.inv = inr :=
by { dsimp [iso_pushout, cocone, comm_sq.cocone], simp, }
@[simp] lemma inl_iso_pushout_hom (h : is_pushout f g inl inr) [has_pushout f g] :
inl ≫ h.iso_pushout.hom = pushout.inl :=
by simp [←iso.eq_comp_inv]
@[simp] lemma inr_iso_pushout_hom (h : is_pushout f g inl inr) [has_pushout f g] :
inr ≫ h.iso_pushout.hom = pushout.inr :=
by simp [←iso.eq_comp_inv]
lemma of_iso_pushout (h : comm_sq f g inl inr) [has_pushout f g] (i : P ≅ pushout f g)
(w₁ : inl ≫ i.hom = pushout.inl) (w₂ : inr ≫ i.hom = pushout.inr) : is_pushout f g inl inr :=
of_is_colimit' h (limits.is_colimit.of_iso_colimit (colimit.is_colimit _)
(@pushout_cocone.ext _ _ _ _ _ _ _ (pushout_cocone.mk _ _ _) _ i w₁ w₂).symm)
end is_pushout
namespace is_pullback
variables {P X Y Z : C} {fst : P ⟶ X} {snd : P ⟶ Y} {f : X ⟶ Z} {g : Y ⟶ Z}
lemma flip (h : is_pullback fst snd f g) : is_pullback snd fst g f :=
of_is_limit (@pullback_cone.flip_is_limit _ _ _ _ _ _ _ _ _ _ h.w.symm h.is_limit)
section
variables [has_zero_object C] [has_zero_morphisms C]
open_locale zero_object
/-- The square with `0 : 0 ⟶ 0` on the left and `𝟙 X` on the right is a pullback square. -/
lemma zero_left (X : C) : is_pullback (0 : 0 ⟶ X) (0 : 0 ⟶ 0) (𝟙 X) (0 : 0 ⟶ X) :=
{ w := by simp,
is_limit' :=
⟨{ lift := λ s, 0,
fac' := λ s, by simpa using @pullback_cone.equalizer_ext _ _ _ _ _ _ _ s _ 0 (𝟙 _)
(by simpa using (pullback_cone.condition s).symm), }⟩ }
/-- The square with `0 : 0 ⟶ 0` on the top and `𝟙 X` on the bottom is a pullback square. -/
lemma zero_top (X : C) : is_pullback (0 : 0 ⟶ 0) (0 : 0 ⟶ X) (0 : 0 ⟶ X) (𝟙 X) :=
(zero_left X).flip
end
/-- Paste two pullback squares "vertically" to obtain another pullback square. -/
-- Objects here are arranged in a 3x2 grid, and indexed by their xy coordinates.
-- Morphisms are named `hᵢⱼ` for a horizontal morphism starting at `(i,j)`,
-- and `vᵢⱼ` for a vertical morphism starting at `(i,j)`.
lemma paste_vert {X₁₁ X₁₂ X₂₁ X₂₂ X₃₁ X₃₂ : C}
{h₁₁ : X₁₁ ⟶ X₁₂} {h₂₁ : X₂₁ ⟶ X₂₂} {h₃₁ : X₃₁ ⟶ X₃₂}
{v₁₁ : X₁₁ ⟶ X₂₁} {v₁₂ : X₁₂ ⟶ X₂₂} {v₂₁ : X₂₁ ⟶ X₃₁} {v₂₂ : X₂₂ ⟶ X₃₂}
(s : is_pullback h₁₁ v₁₁ v₁₂ h₂₁) (t : is_pullback h₂₁ v₂₁ v₂₂ h₃₁) :
is_pullback h₁₁ (v₁₁ ≫ v₂₁) (v₁₂ ≫ v₂₂) h₃₁ :=
(of_is_limit
(big_square_is_pullback _ _ _ _ _ _ _ s.w t.w t.is_limit s.is_limit))
/-- Paste two pullback squares "horizontally" to obtain another pullback square. -/
lemma paste_horiz {X₁₁ X₁₂ X₁₃ X₂₁ X₂₂ X₂₃ : C}
{h₁₁ : X₁₁ ⟶ X₁₂} {h₁₂ : X₁₂ ⟶ X₁₃} {h₂₁ : X₂₁ ⟶ X₂₂} {h₂₂ : X₂₂ ⟶ X₂₃}
{v₁₁ : X₁₁ ⟶ X₂₁} {v₁₂ : X₁₂ ⟶ X₂₂} {v₁₃ : X₁₃ ⟶ X₂₃}
(s : is_pullback h₁₁ v₁₁ v₁₂ h₂₁) (t : is_pullback h₁₂ v₁₂ v₁₃ h₂₂) :
is_pullback (h₁₁ ≫ h₁₂) v₁₁ v₁₃ (h₂₁ ≫ h₂₂) :=
(paste_vert s.flip t.flip).flip
/-- Given a pullback square assembled from a commuting square on the top and
a pullback square on the bottom, the top square is a pullback square. -/
lemma of_bot {X₁₁ X₁₂ X₂₁ X₂₂ X₃₁ X₃₂ : C}
{h₁₁ : X₁₁ ⟶ X₁₂} {h₂₁ : X₂₁ ⟶ X₂₂} {h₃₁ : X₃₁ ⟶ X₃₂}
{v₁₁ : X₁₁ ⟶ X₂₁} {v₁₂ : X₁₂ ⟶ X₂₂} {v₂₁ : X₂₁ ⟶ X₃₁} {v₂₂ : X₂₂ ⟶ X₃₂}
(s : is_pullback h₁₁ (v₁₁ ≫ v₂₁) (v₁₂ ≫ v₂₂) h₃₁) (p : h₁₁ ≫ v₁₂ = v₁₁ ≫ h₂₁)
(t : is_pullback h₂₁ v₂₁ v₂₂ h₃₁) :
is_pullback h₁₁ v₁₁ v₁₂ h₂₁ :=
of_is_limit (left_square_is_pullback _ _ _ _ _ _ _ p _ t.is_limit s.is_limit)
/-- Given a pullback square assembled from a commuting square on the left and
a pullback square on the right, the left square is a pullback square. -/
lemma of_right {X₁₁ X₁₂ X₁₃ X₂₁ X₂₂ X₂₃ : C}
{h₁₁ : X₁₁ ⟶ X₁₂} {h₁₂ : X₁₂ ⟶ X₁₃} {h₂₁ : X₂₁ ⟶ X₂₂} {h₂₂ : X₂₂ ⟶ X₂₃}
{v₁₁ : X₁₁ ⟶ X₂₁} {v₁₂ : X₁₂ ⟶ X₂₂} {v₁₃ : X₁₃ ⟶ X₂₃}
(s : is_pullback (h₁₁ ≫ h₁₂) v₁₁ v₁₃ (h₂₁ ≫ h₂₂)) (p : h₁₁ ≫ v₁₂ = v₁₁ ≫ h₂₁)
(t : is_pullback h₁₂ v₁₂ v₁₃ h₂₂) :
is_pullback h₁₁ v₁₁ v₁₂ h₂₁ :=
(of_bot s.flip p.symm t.flip).flip
end is_pullback
namespace is_pushout
variables {Z X Y P : C} {f : Z ⟶ X} {g : Z ⟶ Y} {inl : X ⟶ P} {inr : Y ⟶ P}
lemma flip (h : is_pushout f g inl inr) : is_pushout g f inr inl :=
of_is_colimit (@pushout_cocone.flip_is_colimit _ _ _ _ _ _ _ _ _ _ h.w.symm h.is_colimit)
section
variables [has_zero_object C] [has_zero_morphisms C]
open_locale zero_object
/-- The square with `0 : 0 ⟶ 0` on the right and `𝟙 X` on the left is a pushout square. -/
lemma zero_right (X : C) : is_pushout (0 : X ⟶ 0) (𝟙 X) (0 : 0 ⟶ 0) (0 : X ⟶ 0) :=
{ w := by simp,
is_colimit' :=
⟨{ desc := λ s, 0,
fac' := λ s, begin
have c := @pushout_cocone.coequalizer_ext _ _ _ _ _ _ _ s _ 0 (𝟙 _) (by simp)
(by simpa using (pushout_cocone.condition s)),
dsimp at c,
simpa using c,
end }⟩ }
/-- The square with `0 : 0 ⟶ 0` on the bottom and `𝟙 X` on the top is a pushout square. -/
lemma zero_bot (X : C) : is_pushout (𝟙 X) (0 : X ⟶ 0) (0 : X ⟶ 0) (0 : 0 ⟶ 0) :=
(zero_right X).flip
end
/-- Paste two pushout squares "vertically" to obtain another pushout square. -/
-- Objects here are arranged in a 3x2 grid, and indexed by their xy coordinates.
-- Morphisms are named `hᵢⱼ` for a horizontal morphism starting at `(i,j)`,
-- and `vᵢⱼ` for a vertical morphism starting at `(i,j)`.
lemma paste_vert {X₁₁ X₁₂ X₂₁ X₂₂ X₃₁ X₃₂ : C}
{h₁₁ : X₁₁ ⟶ X₁₂} {h₂₁ : X₂₁ ⟶ X₂₂} {h₃₁ : X₃₁ ⟶ X₃₂}
{v₁₁ : X₁₁ ⟶ X₂₁} {v₁₂ : X₁₂ ⟶ X₂₂} {v₂₁ : X₂₁ ⟶ X₃₁} {v₂₂ : X₂₂ ⟶ X₃₂}
(s : is_pushout h₁₁ v₁₁ v₁₂ h₂₁) (t : is_pushout h₂₁ v₂₁ v₂₂ h₃₁) :
is_pushout h₁₁ (v₁₁ ≫ v₂₁) (v₁₂ ≫ v₂₂) h₃₁ :=
(of_is_colimit
(big_square_is_pushout _ _ _ _ _ _ _ s.w t.w t.is_colimit s.is_colimit))
/-- Paste two pushout squares "horizontally" to obtain another pushout square. -/
lemma paste_horiz {X₁₁ X₁₂ X₁₃ X₂₁ X₂₂ X₂₃ : C}
{h₁₁ : X₁₁ ⟶ X₁₂} {h₁₂ : X₁₂ ⟶ X₁₃} {h₂₁ : X₂₁ ⟶ X₂₂} {h₂₂ : X₂₂ ⟶ X₂₃}
{v₁₁ : X₁₁ ⟶ X₂₁} {v₁₂ : X₁₂ ⟶ X₂₂} {v₁₃ : X₁₃ ⟶ X₂₃}
(s : is_pushout h₁₁ v₁₁ v₁₂ h₂₁) (t : is_pushout h₁₂ v₁₂ v₁₃ h₂₂) :
is_pushout (h₁₁ ≫ h₁₂) v₁₁ v₁₃ (h₂₁ ≫ h₂₂) :=
(paste_vert s.flip t.flip).flip
/-- Given a pushout square assembled from a pushout square on the top and
a commuting square on the bottom, the bottom square is a pushout square. -/
lemma of_bot {X₁₁ X₁₂ X₂₁ X₂₂ X₃₁ X₃₂ : C}
{h₁₁ : X₁₁ ⟶ X₁₂} {h₂₁ : X₂₁ ⟶ X₂₂} {h₃₁ : X₃₁ ⟶ X₃₂}
{v₁₁ : X₁₁ ⟶ X₂₁} {v₁₂ : X₁₂ ⟶ X₂₂} {v₂₁ : X₂₁ ⟶ X₃₁} {v₂₂ : X₂₂ ⟶ X₃₂}
(s : is_pushout h₁₁ (v₁₁ ≫ v₂₁) (v₁₂ ≫ v₂₂) h₃₁) (p : h₂₁ ≫ v₂₂ = v₂₁ ≫ h₃₁)
(t : is_pushout h₁₁ v₁₁ v₁₂ h₂₁) :
is_pushout h₂₁ v₂₁ v₂₂ h₃₁ :=
of_is_colimit (right_square_is_pushout _ _ _ _ _ _ _ _ p t.is_colimit s.is_colimit)
/-- Given a pushout square assembled from a pushout square on the left and
a commuting square on the right, the right square is a pushout square. -/
lemma of_right {X₁₁ X₁₂ X₁₃ X₂₁ X₂₂ X₂₃ : C}
{h₁₁ : X₁₁ ⟶ X₁₂} {h₁₂ : X₁₂ ⟶ X₁₃} {h₂₁ : X₂₁ ⟶ X₂₂} {h₂₂ : X₂₂ ⟶ X₂₃}
{v₁₁ : X₁₁ ⟶ X₂₁} {v₁₂ : X₁₂ ⟶ X₂₂} {v₁₃ : X₁₃ ⟶ X₂₃}
(s : is_pushout (h₁₁ ≫ h₁₂) v₁₁ v₁₃ (h₂₁ ≫ h₂₂)) (p : h₁₂ ≫ v₁₃ = v₁₂ ≫ h₂₂)
(t : is_pushout h₁₁ v₁₁ v₁₂ h₂₁) :
is_pushout h₁₂ v₁₂ v₁₃ h₂₂ :=
(of_bot s.flip p.symm t.flip).flip
end is_pushout
namespace functor
variables {D : Type u₂} [category.{v₂} D]
variables (F : C ⥤ D) {W X Y Z : C} {f : W ⟶ X} {g : W ⟶ Y} {h : X ⟶ Z} {i : Y ⟶ Z}
lemma map_comm_sq (s : comm_sq f g h i) : comm_sq (F.map f) (F.map g) (F.map h) (F.map i) :=
⟨by simpa using congr_arg (λ k : W ⟶ Z, F.map k) s.w⟩
lemma map_is_pullback [preserves_limit (cospan h i) F] (s : is_pullback f g h i) :
is_pullback (F.map f) (F.map g) (F.map h) (F.map i) :=
-- This is made slightly awkward because `C` and `D` have different universes,
-- and so the relevant `walking_cospan` diagrams live in different universes too!
begin
refine is_pullback.of_is_limit' (F.map_comm_sq s.to_comm_sq)
(is_limit.equiv_of_nat_iso_of_iso (cospan_comp_iso F h i) _ _ (walking_cospan.ext _ _ _)
(is_limit_of_preserves F s.is_limit)),
{ refl, },
{ dsimp, simp, refl, },
{ dsimp, simp, refl, },
end
lemma map_is_pushout [preserves_colimit (span f g) F] (s : is_pushout f g h i) :
is_pushout (F.map f) (F.map g) (F.map h) (F.map i) :=
begin
refine is_pushout.of_is_colimit' (F.map_comm_sq s.to_comm_sq)
(is_colimit.equiv_of_nat_iso_of_iso (span_comp_iso F f g) _ _ (walking_span.ext _ _ _)
(is_colimit_of_preserves F s.is_colimit)),
{ refl, },
{ dsimp, simp, refl, },
{ dsimp, simp, refl, },
end
end functor
alias functor.map_comm_sq ← comm_sq.map
alias functor.map_is_pullback ← is_pullback.map
alias functor.map_is_pushout ← is_pushout.map
end category_theory
|
6960ec8c5805361243252b7b78ba8b9aacfba111 | b70447c014d9e71cf619ebc9f539b262c19c2e0b | /hott/types/nat/hott.hlean | f4bcf4460f42fa5e2ef1b165ad212a85828942b0 | [
"Apache-2.0"
] | permissive | ia0/lean2 | c20d8da69657f94b1d161f9590a4c635f8dc87f3 | d86284da630acb78fa5dc3b0b106153c50ffccd0 | refs/heads/master | 1,611,399,322,751 | 1,495,751,007,000 | 1,495,751,007,000 | 93,104,167 | 0 | 0 | null | 1,496,355,488,000 | 1,496,355,487,000 | null | UTF-8 | Lean | false | false | 7,936 | hlean | /-
Copyright (c) 2015 Floris van Doorn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Floris van Doorn
Theorems about the natural numbers specific to HoTT
-/
import .order types.pointed
open is_trunc unit empty eq equiv algebra pointed
namespace nat
definition is_prop_le [instance] (n m : ℕ) : is_prop (n ≤ m) :=
begin
have lem : Π{n m : ℕ} (p : n ≤ m) (q : n = m), p = q ▸ le.refl n,
begin
intros, cases p,
{ have H' : q = idp, by apply is_set.elim,
cases H', reflexivity},
{ cases q, exfalso, apply not_succ_le_self a}
end,
apply is_prop.mk, intro H1 H2, induction H2,
{ apply lem},
{ cases H1,
{ exfalso, apply not_succ_le_self a},
{ exact ap le.step !v_0}},
end
definition is_prop_lt [instance] (n m : ℕ) : is_prop (n < m) := !is_prop_le
definition le_equiv_succ_le_succ (n m : ℕ) : (n ≤ m) ≃ (succ n ≤ succ m) :=
equiv_of_is_prop succ_le_succ le_of_succ_le_succ
definition le_succ_equiv_pred_le (n m : ℕ) : (n ≤ succ m) ≃ (pred n ≤ m) :=
equiv_of_is_prop pred_le_pred le_succ_of_pred_le
theorem lt_by_cases_lt {a b : ℕ} {P : Type} (H1 : a < b → P) (H2 : a = b → P)
(H3 : a > b → P) (H : a < b) : lt.by_cases H1 H2 H3 = H1 H :=
begin
unfold lt.by_cases, induction (lt.trichotomy a b) with H' H',
{ esimp, exact ap H1 !is_prop.elim},
{ exfalso, cases H' with H' H', apply lt.irrefl, exact H' ▸ H, exact lt.asymm H H'}
end
theorem lt_by_cases_eq {a b : ℕ} {P : Type} (H1 : a < b → P) (H2 : a = b → P)
(H3 : a > b → P) (H : a = b) : lt.by_cases H1 H2 H3 = H2 H :=
begin
unfold lt.by_cases, induction (lt.trichotomy a b) with H' H',
{ exfalso, apply lt.irrefl, exact H ▸ H'},
{ cases H' with H' H', esimp, exact ap H2 !is_prop.elim, exfalso, apply lt.irrefl, exact H ▸ H'}
end
theorem lt_by_cases_ge {a b : ℕ} {P : Type} (H1 : a < b → P) (H2 : a = b → P)
(H3 : a > b → P) (H : a > b) : lt.by_cases H1 H2 H3 = H3 H :=
begin
unfold lt.by_cases, induction (lt.trichotomy a b) with H' H',
{ exfalso, exact lt.asymm H H'},
{ cases H' with H' H', exfalso, apply lt.irrefl, exact H' ▸ H, esimp, exact ap H3 !is_prop.elim}
end
theorem lt_ge_by_cases_lt {n m : ℕ} {P : Type} (H1 : n < m → P) (H2 : n ≥ m → P)
(H : n < m) : lt_ge_by_cases H1 H2 = H1 H :=
by apply lt_by_cases_lt
theorem lt_ge_by_cases_ge {n m : ℕ} {P : Type} (H1 : n < m → P) (H2 : n ≥ m → P)
(H : n ≥ m) : lt_ge_by_cases H1 H2 = H2 H :=
begin
unfold [lt_ge_by_cases,lt.by_cases], induction (lt.trichotomy n m) with H' H',
{ exfalso, apply lt.irrefl, exact lt_of_le_of_lt H H'},
{ cases H' with H' H'; all_goals (esimp; apply ap H2 !is_prop.elim)}
end
theorem lt_ge_by_cases_le {n m : ℕ} {P : Type} {H1 : n ≤ m → P} {H2 : n ≥ m → P}
(H : n ≤ m) (Heq : Π(p : n = m), H1 (le_of_eq p) = H2 (le_of_eq p⁻¹))
: lt_ge_by_cases (λH', H1 (le_of_lt H')) H2 = H1 H :=
begin
unfold [lt_ge_by_cases,lt.by_cases], induction (lt.trichotomy n m) with H' H',
{ esimp, apply ap H1 !is_prop.elim},
{ cases H' with H' H',
{ esimp, induction H', esimp, symmetry,
exact ap H1 !is_prop.elim ⬝ Heq idp ⬝ ap H2 !is_prop.elim},
{ exfalso, apply lt.irrefl, apply lt_of_le_of_lt H H'}}
end
protected definition code [reducible] [unfold 1 2] : ℕ → ℕ → Type₀
| code 0 0 := unit
| code 0 (succ m) := empty
| code (succ n) 0 := empty
| code (succ n) (succ m) := code n m
protected definition refl : Πn, nat.code n n
| refl 0 := star
| refl (succ n) := refl n
protected definition encode [unfold 3] {n m : ℕ} (p : n = m) : nat.code n m :=
p ▸ nat.refl n
protected definition decode : Π(n m : ℕ), nat.code n m → n = m
| decode 0 0 := λc, idp
| decode 0 (succ l) := λc, empty.elim c _
| decode (succ k) 0 := λc, empty.elim c _
| decode (succ k) (succ l) := λc, ap succ (decode k l c)
definition nat_eq_equiv (n m : ℕ) : (n = m) ≃ nat.code n m :=
equiv.MK nat.encode
!nat.decode
begin
revert m, induction n, all_goals (intro m;induction m;all_goals intro c),
all_goals try contradiction,
induction c, reflexivity,
xrewrite [↑nat.decode,-tr_compose,v_0],
end
begin
intro p, induction p, esimp, induction n,
reflexivity,
rewrite [↑nat.decode,↑nat.refl,v_0]
end
definition pointed_nat [instance] [constructor] : pointed ℕ :=
pointed.mk 0
open sigma sum
definition eq_even_or_eq_odd (n : ℕ) : (Σk, 2 * k = n) ⊎ (Σk, 2 * k + 1 = n) :=
begin
induction n with n IH,
{ exact inl ⟨0, idp⟩},
{ induction IH with H H: induction H with k p: induction p,
{ exact inr ⟨k, idp⟩},
{ refine inl ⟨k+1, idp⟩}}
end
definition rec_on_even_odd {P : ℕ → Type} (n : ℕ) (H : Πk, P (2 * k)) (H2 : Πk, P (2 * k + 1))
: P n :=
begin
cases eq_even_or_eq_odd n with v v: induction v with k p: induction p,
{ exact H k},
{ exact H2 k}
end
/- this inequality comes up a couple of times when using the freudenthal suspension theorem -/
definition add_mul_le_mul_add (n m k : ℕ) : n + (succ m) * k ≤ (succ m) * (n + k) :=
calc
n + (succ m) * k ≤ (m * n + n) + (succ m) * k : add_le_add_right !le_add_left _
... = (succ m) * n + (succ m) * k : by rewrite -succ_mul
... = (succ m) * (n + k) : !left_distrib⁻¹
/-
Some operations work only for successors. For example fin (succ n) has a 0 and a 1, but fin 0
doesn't. However, we want a bit more, because sometimes we want a zero of (fin a)
where a is either
- equal to a successor, but not definitionally a successor (e.g. (0 : fin (3 + n)))
- definitionally equal to a successor, but not in a way that type class inference can infer.
(e.g. (0 : fin 4). Note that 4 is bit0 (bit0 one), but (bit0 x) (defined as x + x),
is not always a successor)
To solve this we use an auxillary class `is_succ` which can solve whether a number is a
successor.
-/
inductive is_succ [class] : ℕ → Type :=
| mk : Π(n : ℕ), is_succ (succ n)
attribute is_succ.mk [instance]
definition is_succ_add_right [instance] [constructor] (n m : ℕ) [H : is_succ m] : is_succ (n+m) :=
by induction H with m; constructor
definition is_succ_add_left [instance] [constructor] (n m : ℕ) [H : is_succ n] : is_succ (n+m) :=
by induction H with n; cases m with m: constructor
definition is_succ_bit0 [constructor] (n : ℕ) [H : is_succ n] : is_succ (bit0 n) :=
by exact _
-- level 2 is useful for abelian homotopy groups, which only exist at level 2 and higher
inductive is_at_least_two [class] : ℕ → Type :=
| mk : Π(n : ℕ), is_at_least_two (succ (succ n))
attribute is_at_least_two.mk [instance]
definition is_at_least_two_add_right [instance] [constructor] (n m : ℕ) [H : is_at_least_two m] :
is_at_least_two (n+m) :=
by induction H with m; constructor
definition is_at_least_two_add_left [instance] [constructor] (n m : ℕ) [H : is_at_least_two n] :
is_at_least_two (n+m) :=
by induction H with n; cases m with m: try cases m with m: constructor
definition is_at_least_two_add_both [instance] [priority 900] [constructor] (n m : ℕ)
[H : is_succ n] [K : is_succ m] : is_at_least_two (n+m) :=
by induction H with n; induction K with m; cases m with m: constructor
definition is_at_least_two_bit0 [constructor] (n : ℕ) [H : is_succ n] : is_at_least_two (bit0 n) :=
by exact _
definition is_at_least_two_bit1 [constructor] (n : ℕ) [H : is_succ n] : is_at_least_two (bit1 n) :=
by exact _
end nat
|
bdcf67c95e2230d06d02cca079655db3ab14403a | 05f637fa14ac28031cb1ea92086a0f4eb23ff2b1 | /tests/lean/lua1.lean | b72bb68e3af2f214c555a04aff5863dc0be134dc | [
"Apache-2.0"
] | permissive | codyroux/lean0.1 | 1ce92751d664aacff0529e139083304a7bbc8a71 | 0dc6fb974aa85ed6f305a2f4b10a53a44ee5f0ef | refs/heads/master | 1,610,830,535,062 | 1,402,150,480,000 | 1,402,150,480,000 | 19,588,851 | 2 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 84 | lean | import Int.
variable x : Int
(*
print("hello world from Lua")
*)
variable y : Int
|
940811146312045f18d91eafbef1eea4101bac3b | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/eq_mpr_def_issue.lean | c9383d33d6ef2489f45770b609bbbabe811da316 | [
"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 | 179 | lean | open function
instance decidable_uncurry_pred{α} (p : α → α → Prop) [decidable_rel p] : decidable_pred (uncurry p) :=
λ a, by { cases a; simp [uncurry]; apply_instance }
|
309c23185924215346742ab968645806e09bf7b7 | 80cc5bf14c8ea85ff340d1d747a127dcadeb966f | /src/number_theory/primorial.lean | e78be6ffa179d92e78d73ff5c0a7819d3fd2cabc | [
"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 | 7,341 | lean | /-
Copyright (c) 2020 Patrick Stevens. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Patrick Stevens
-/
import tactic.ring_exp
import data.nat.parity
import data.nat.choose.sum
/-!
# Primorial
This file defines the primorial function (the product of primes less than or equal to some bound),
and proves that `primorial n ≤ 4 ^ n`.
## Notations
We use the local notation `n#` for the primorial of `n`: that is, the product of the primes less
than or equal to `n`.
-/
open finset
open nat
open_locale big_operators
/-- The primorial `n#` of `n` is the product of the primes less than or equal to `n`.
-/
def primorial (n : ℕ) : ℕ := ∏ p in (filter prime (range (n + 1))), p
local notation x`#` := primorial x
lemma primorial_succ {n : ℕ} (n_big : 1 < n) (r : n % 2 = 1) : (n + 1)# = n# :=
begin
have not_prime : ¬prime (n + 1),
{ intros is_prime,
cases (prime.eq_two_or_odd is_prime) with _ n_even,
{ linarith, },
{ exfalso,
rw ←not_even_iff at n_even r,
have e : even (n + 1 - n), exact (even_sub (le_of_lt (lt_add_one n))).2 (iff_of_false n_even r),
simp only [nat.add_sub_cancel_left, not_even_one] at e,
exact e, }, },
apply finset.prod_congr,
{ rw [@range_succ (n + 1), filter_insert, if_neg not_prime], },
{ exact λ _ _, rfl, },
end
lemma dvd_choose_of_middling_prime (p : ℕ) (is_prime : prime p) (m : ℕ)
(p_big : m + 1 < p) (p_small : p ≤ 2 * m + 1) : p ∣ choose (2 * m + 1) (m + 1) :=
begin
have m_size : m + 1 ≤ 2 * m + 1 := le_of_lt (lt_of_lt_of_le p_big p_small),
have expanded :
choose (2 * m + 1) (m + 1) * fact (m + 1) * fact (2 * m + 1 - (m + 1)) = fact (2 * m + 1) :=
@choose_mul_fact_mul_fact (2 * m + 1) (m + 1) m_size,
have p_div_big_fact : p ∣ fact (2 * m + 1) := (prime.dvd_fact is_prime).mpr p_small,
rw [←expanded, mul_assoc] at p_div_big_fact,
have s : ¬(p ∣ fact (m + 1)),
{ intros p_div_fact,
have p_le_succ_m : p ≤ m + 1 := (prime.dvd_fact is_prime).mp p_div_fact,
linarith, },
have t : ¬(p ∣ fact (2 * m + 1 - (m + 1))),
{ intros p_div_fact,
have p_small : p ≤ 2 * m + 1 - (m + 1) := (prime.dvd_fact is_prime).mp p_div_fact,
have t : 2 * m + 1 - (m + 1) = m, by { norm_num, rw two_mul m, exact nat.add_sub_cancel m m, },
rw t at p_small,
obtain p_lt_m | rfl | m_lt_p : _ := lt_trichotomy p m,
{ have r : m < m + 1 := lt_add_one m, linarith, },
{ linarith, },
{ linarith, }, },
obtain p_div_choose | p_div_facts : p ∣ choose (2 * m + 1) (m + 1) ∨ p ∣ fact _ * fact _ :=
(prime.dvd_mul is_prime).1 p_div_big_fact,
{ exact p_div_choose, },
cases (prime.dvd_mul is_prime).1 p_div_facts,
cc, cc,
end
lemma prod_primes_dvd {s : finset ℕ} : ∀ (n : ℕ) (h : ∀ a ∈ s, prime a) (div : ∀ a ∈ s, a ∣ n),
(∏ p in s, p) ∣ n :=
begin
apply finset.induction_on s,
{ simp, },
{ intros a s a_not_in_s induct n primes divs,
rw finset.prod_insert a_not_in_s,
obtain ⟨k, rfl⟩ : a ∣ n, by exact divs a (finset.mem_insert_self a s),
have step : ∏ p in s, p ∣ k,
{ apply induct k,
{ intros b b_in_s,
exact primes b (finset.mem_insert_of_mem b_in_s), },
{ intros b b_in_s,
have b_div_n, by exact divs b (finset.mem_insert_of_mem b_in_s),
have a_prime : prime a, { exact primes a (finset.mem_insert_self a s), },
have b_prime : prime b, { exact primes b (finset.mem_insert_of_mem b_in_s), },
obtain b_div_a | b_div_k : b ∣ a ∨ b ∣ k, exact (prime.dvd_mul b_prime).mp b_div_n,
{ exfalso,
have b_eq_a : b = a,
{ cases (nat.dvd_prime a_prime).1 b_div_a with b_eq_1 b_eq_a,
{ subst b_eq_1, exfalso, exact prime.ne_one b_prime rfl, },
{ exact b_eq_a } },
subst b_eq_a,
exact a_not_in_s b_in_s, },
{ exact b_div_k } } },
exact mul_dvd_mul_left a step, }
end
lemma primorial_le_4_pow : ∀ (n : ℕ), n# ≤ 4 ^ n
| 0 := le_refl _
| 1 := le_of_inf_eq rfl
| (n + 2) :=
match nat.mod_two_eq_zero_or_one (n + 1) with
| or.inl n_odd :=
match nat.even_iff.2 n_odd with
| ⟨m, twice_m⟩ :=
let recurse : m + 1 < n + 2 := by linarith in
begin
calc (n + 2)#
= ∏ i in filter prime (range (2 * m + 2)), i : by simpa [←twice_m]
... = ∏ i in filter prime (finset.Ico (m + 2) (2 * m + 2) ∪ range (m + 2)), i :
begin
rw [range_eq_Ico, range_eq_Ico, finset.union_comm, finset.Ico.union_consecutive],
exact bot_le,
simp only [add_le_add_iff_right],
linarith,
end
... = ∏ i in (filter prime (finset.Ico (m + 2) (2 * m + 2)) ∪ (filter prime (range (m + 2)))), i :
by rw filter_union
... = (∏ i in filter prime (finset.Ico (m + 2) (2 * m + 2)), i)
* (∏ i in filter prime (range (m + 2)), i) :
begin
apply finset.prod_union,
have disj : disjoint (finset.Ico (m + 2) (2 * m + 2)) (range (m + 2)),
{ simp only [finset.disjoint_left, and_imp, finset.Ico.mem, not_lt, finset.mem_range],
intros _ pr _, exact pr, },
exact finset.disjoint_filter_filter disj,
end
... ≤ (∏ i in filter prime (finset.Ico (m + 2) (2 * m + 2)), i) * 4 ^ (m + 1) :
by exact nat.mul_le_mul_left _ (primorial_le_4_pow (m + 1))
... ≤ (choose (2 * m + 1) (m + 1)) * 4 ^ (m + 1) :
begin
have s : ∏ i in filter prime (finset.Ico (m + 2) (2 * m + 2)), i ∣ choose (2 * m + 1) (m + 1),
{ refine prod_primes_dvd (choose (2 * m + 1) (m + 1)) _ _,
{ intros a, rw finset.mem_filter, cc, },
{ intros a, rw finset.mem_filter,
intros pr,
rcases pr with ⟨ size, is_prime ⟩,
simp only [finset.Ico.mem] at size,
rcases size with ⟨ a_big , a_small ⟩,
exact dvd_choose_of_middling_prime a is_prime m a_big (nat.lt_succ_iff.mp a_small), }, },
have r : ∏ i in filter prime (finset.Ico (m + 2) (2 * m + 2)), i ≤ choose (2 * m + 1) (m + 1),
{ refine @nat.le_of_dvd _ _ _ s,
exact @choose_pos (2 * m + 1) (m + 1) (by linarith), },
exact nat.mul_le_mul_right _ r,
end
... = (choose (2 * m + 1) m) * 4 ^ (m + 1) : by rw choose_symm_half m
... ≤ 4 ^ m * 4 ^ (m + 1) : nat.mul_le_mul_right _ (choose_middle_le_pow m)
... = 4 ^ (2 * m + 1) : by ring_exp
... = 4 ^ (n + 2) : by rw ←twice_m,
end
end
| or.inr n_even :=
begin
obtain one_lt_n | n_le_one : 1 < n + 1 ∨ n + 1 ≤ 1 := lt_or_le 1 (n + 1),
{ rw primorial_succ (by linarith) n_even,
calc (n + 1)#
≤ 4 ^ n.succ : primorial_le_4_pow (n + 1)
... ≤ 4 ^ (n + 2) : pow_le_pow (by norm_num) (nat.le_succ _), },
{ cases lt_or_le 0 n with _ n_le_zero,
{ linarith, },
{ have n_zero : n = 0 := eq_bot_iff.mpr n_le_zero,
norm_num [n_zero],
exact sup_eq_left.mp rfl, }, },
end
end
|
abe61070cba62103da23c723af96892284d50bb1 | 5bf112cf7101c6c6303dc3fd0b3179c860e61e56 | /lean/background/number.lean | 15c930d93f5c98feeba59a8d20e74f4dd8c79e80 | [
"Apache-2.0"
] | permissive | fredfeng/formal-encoding | 7ab645f49a553dfad2af03fcb4289e40fc679759 | 024efcf58672ac6b817caa10dfe8cd9708b07f1b | refs/heads/master | 1,597,236,551,123 | 1,568,832,149,000 | 1,568,832,149,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 1,687 | lean | import .util
namespace IMOGrandChallenge
notation `ℕ` := Nat
notation `ℕgt0` := { n : ℕ // n > 0 }
notation `ℤ` := Int
notation `ℤgt0` := { z : ℤ // z > 0 }
notation `ℤge0` := { z : ℤ // z ≥ 0 }
axiom Rat : Type
notation `ℚ` := Rat
namespace Rat
noncomputable instance : HasZero ℚ := ⟨SKIP⟩
noncomputable instance : HasOne ℚ := ⟨SKIP⟩
noncomputable instance : HasAdd ℚ := ⟨SKIP⟩
noncomputable instance : HasMul ℚ := ⟨SKIP⟩
noncomputable instance : HasNeg ℚ := ⟨SKIP⟩
noncomputable instance : HasSub ℚ := ⟨SKIP⟩
noncomputable instance : HasDiv ℚ := ⟨SKIP⟩
noncomputable instance : HasPow ℚ ℚ := ⟨SKIP⟩
noncomputable instance : HasLess ℚ := ⟨SKIP⟩
notation `ℚgt0` := { r : ℚ // r > 0 }
notation `ℚge0` := { r : ℚ // r ≥ 0 }
axiom isInt : ℚ → Prop
end Rat
axiom Nat.toRat : ℕ → ℚ
axiom Real : Type
notation `ℝ` := Real
namespace Real
noncomputable instance : HasZero ℝ := ⟨SKIP⟩
noncomputable instance : HasOne ℝ := ⟨SKIP⟩
noncomputable instance : HasAdd ℝ := ⟨SKIP⟩
noncomputable instance : HasMul ℝ := ⟨SKIP⟩
noncomputable instance : HasNeg ℝ := ⟨SKIP⟩
noncomputable instance : HasSub ℝ := ⟨SKIP⟩
noncomputable instance : HasDiv ℝ := ⟨SKIP⟩
noncomputable instance HasPowℝℕ : HasPow ℝ ℕ := ⟨SKIP⟩
noncomputable instance HasPowℝℝ : HasPow ℝ ℝ := ⟨SKIP⟩
noncomputable instance : HasLess ℝ := ⟨SKIP⟩
notation `ℝgt0` := { x : ℝ // x > 0 }
notation `ℝge0` := { x : ℝ // x ≥ 0 }
axiom e : ℝ
axiom pi : ℝ
noncomputable def sqrt (x : Real) : Real := pow x (1/2)
end Real
end IMOGrandChallenge
|
f936d10af3b015aaa79ba4608bef4c51f1ec400e | 367134ba5a65885e863bdc4507601606690974c1 | /src/data/vector2.lean | 06a048fe9ca0703b72ffe1e32d1447b2d7dedf57 | [
"Apache-2.0"
] | permissive | kodyvajjha/mathlib | 9bead00e90f68269a313f45f5561766cfd8d5cad | b98af5dd79e13a38d84438b850a2e8858ec21284 | refs/heads/master | 1,624,350,366,310 | 1,615,563,062,000 | 1,615,563,062,000 | 162,666,963 | 0 | 0 | Apache-2.0 | 1,545,367,651,000 | 1,545,367,651,000 | null | UTF-8 | Lean | false | false | 16,312 | 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.vector
import data.list.nodup
import data.list.of_fn
import control.applicative
/-!
# Additional theorems about the `vector` type
This file introduces the infix notation `::ᵥ` for `vector.cons`.
-/
universes u
variables {n : ℕ}
namespace vector
variables {α : Type*}
infixr `::ᵥ`:67 := vector.cons
attribute [simp] head_cons tail_cons
instance [inhabited α] : inhabited (vector α n) :=
⟨of_fn (λ _, default α)⟩
theorem to_list_injective : function.injective (@to_list α n) :=
subtype.val_injective
/-- Two `v w : vector α n` are equal iff they are equal at every single index. -/
@[ext] theorem ext : ∀ {v w : vector α n}
(h : ∀ m : fin n, vector.nth v m = vector.nth w m), v = w
| ⟨v, hv⟩ ⟨w, hw⟩ h := subtype.eq (list.ext_le (by rw [hv, hw])
(λ m hm hn, h ⟨m, hv ▸ hm⟩))
/-- The empty `vector` is a `subsingleton`. -/
instance zero_subsingleton : subsingleton (vector α 0) :=
⟨λ _ _, vector.ext (λ m, fin.elim0 m)⟩
@[simp] theorem cons_val (a : α) : ∀ (v : vector α n), (a ::ᵥ v).val = a :: v.val
| ⟨_, _⟩ := rfl
@[simp] theorem cons_head (a : α) : ∀ (v : vector α n), (a ::ᵥ v).head = a
| ⟨_, _⟩ := rfl
@[simp] theorem cons_tail (a : α) : ∀ (v : vector α n), (a ::ᵥ v).tail = v
| ⟨_, _⟩ := rfl
@[simp] theorem to_list_of_fn : ∀ {n} (f : fin n → α), to_list (of_fn f) = list.of_fn f
| 0 f := rfl
| (n+1) f := by rw [of_fn, list.of_fn_succ, to_list_cons, to_list_of_fn]
@[simp] theorem mk_to_list :
∀ (v : vector α n) h, (⟨to_list v, h⟩ : vector α n) = v
| ⟨l, h₁⟩ h₂ := rfl
@[simp] lemma to_list_map {β : Type*} (v : vector α n) (f : α → β) : (v.map f).to_list =
v.to_list.map f := by cases v; refl
theorem nth_eq_nth_le : ∀ (v : vector α n) (i),
nth v i = v.to_list.nth_le i.1 (by rw to_list_length; exact i.2)
| ⟨l, h⟩ i := rfl
@[simp] lemma nth_map {β : Type*} (v : vector α n) (f : α → β) (i : fin n) :
(v.map f).nth i = f (v.nth i) :=
by simp [nth_eq_nth_le]
@[simp] theorem nth_of_fn {n} (f : fin n → α) (i) : nth (of_fn f) i = f i :=
by rw [nth_eq_nth_le, ← list.nth_le_of_fn f];
congr; apply to_list_of_fn
@[simp] theorem of_fn_nth (v : vector α n) : of_fn (nth v) = v :=
begin
rcases v with ⟨l, rfl⟩,
apply to_list_injective,
change nth ⟨l, eq.refl _⟩ with λ i, nth ⟨l, rfl⟩ i,
simpa only [to_list_of_fn] using list.of_fn_nth_le _
end
@[simp] theorem nth_tail : ∀ (v : vector α n.succ) (i : fin n),
nth (tail v) i = nth v i.succ
| ⟨a::l, e⟩ ⟨i, h⟩ := by simp [nth_eq_nth_le]; refl
@[simp] theorem tail_val : ∀ (v : vector α n.succ), v.tail.val = v.val.tail
| ⟨a::l, e⟩ := rfl
/-- The `tail` of a `nil` vector is `nil`. -/
@[simp] lemma tail_nil : (@nil α).tail = nil := rfl
/-- The `tail` of a vector made up of one element is `nil`. -/
@[simp] lemma singleton_tail (v : vector α 1) : v.tail = vector.nil :=
by simp only [←cons_head_tail, eq_iff_true_of_subsingleton]
@[simp] theorem tail_of_fn {n : ℕ} (f : fin n.succ → α) :
tail (of_fn f) = of_fn (λ i, f i.succ) :=
(of_fn_nth _).symm.trans $ by congr; funext i; simp
/-- The list that makes up a `vector` made up of a single element,
retrieved via `to_list`, is equal to the list of that single element. -/
@[simp] lemma to_list_singleton (v : vector α 1) : v.to_list = [v.head] :=
begin
rw ←v.cons_head_tail,
simp only [to_list_cons, to_list_nil, cons_head, eq_self_iff_true,
and_self, singleton_tail]
end
/-- Mapping under `id` does not change a vector. -/
@[simp] lemma map_id {n : ℕ} (v : vector α n) : vector.map id v = v :=
vector.eq _ _ (by simp only [list.map_id, vector.to_list_map])
lemma mem_iff_nth {a : α} {v : vector α n} : a ∈ v.to_list ↔ ∃ i, v.nth i = a :=
by simp only [list.mem_iff_nth_le, fin.exists_iff, vector.nth_eq_nth_le];
exact ⟨λ ⟨i, hi, h⟩, ⟨i, by rwa to_list_length at hi, h⟩,
λ ⟨i, hi, h⟩, ⟨i, by rwa to_list_length, h⟩⟩
lemma nodup_iff_nth_inj {v : vector α n} : v.to_list.nodup ↔ function.injective v.nth :=
begin
cases v with l hl,
subst hl,
simp only [list.nodup_iff_nth_le_inj],
split,
{ intros h i j hij,
cases i, cases j, ext, apply h, simpa },
{ intros h i j hi hj hij,
have := @h ⟨i, hi⟩ ⟨j, hj⟩, simp [nth_eq_nth_le] at *, tauto }
end
@[simp] lemma nth_mem (i : fin n) (v : vector α n) : v.nth i ∈ v.to_list :=
by rw [nth_eq_nth_le]; exact list.nth_le_mem _ _ _
theorem head'_to_list : ∀ (v : vector α n.succ),
(to_list v).head' = some (head v)
| ⟨a::l, e⟩ := rfl
def reverse (v : vector α n) : vector α n :=
⟨v.to_list.reverse, by simp⟩
/-- The `list` of a vector after a `reverse`, retrieved by `to_list` is equal
to the `list.reverse` after retrieving a vector's `to_list`. -/
lemma to_list_reverse {v : vector α n} : v.reverse.to_list = v.to_list.reverse := rfl
@[simp] theorem nth_zero : ∀ (v : vector α n.succ), nth v 0 = head v
| ⟨a::l, e⟩ := rfl
@[simp] theorem head_of_fn
{n : ℕ} (f : fin n.succ → α) : head (of_fn f) = f 0 :=
by rw [← nth_zero, nth_of_fn]
@[simp] theorem nth_cons_zero
(a : α) (v : vector α n) : nth (a ::ᵥ v) 0 = a :=
by simp [nth_zero]
/-- Accessing the `nth` element of a vector made up
of one element `x : α` is `x` itself. -/
@[simp] lemma nth_cons_nil {ix : fin 1}
(x : α) : nth (x ::ᵥ nil) ix = x :=
by convert nth_cons_zero x nil
@[simp] theorem nth_cons_succ
(a : α) (v : vector α n) (i : fin n) : nth (a ::ᵥ v) i.succ = nth v i :=
by rw [← nth_tail, tail_cons]
/-- The last element of a `vector`, given that the vector is at least one element. -/
def last (v : vector α (n + 1)) : α := v.nth (fin.last n)
/-- The last element of a `vector`, given that the vector is at least one element. -/
lemma last_def {v : vector α (n + 1)} : v.last = v.nth (fin.last n) := rfl
/-- The `last` element of a vector is the `head` of the `reverse` vector. -/
lemma reverse_nth_zero {v : vector α (n + 1)} : v.reverse.head = v.last :=
begin
have : 0 = v.to_list.length - 1 - n,
{ simp only [nat.add_succ_sub_one, add_zero, to_list_length, nat.sub_self,
list.length_reverse] },
rw [←nth_zero, last_def, nth_eq_nth_le, nth_eq_nth_le],
simp_rw [to_list_reverse, fin.val_eq_coe, fin.coe_last, fin.coe_zero, this],
rw list.nth_le_reverse,
end
section scan
variables {β : Type*}
variables (f : β → α → β) (b : β)
variables (v : vector α n)
/--
Construct a `vector β (n + 1)` from a `vector α n` by scanning `f : β → α → β`
from the "left", that is, from 0 to `fin.last n`, using `b : β` as the starting value.
-/
def scanl : vector β (n + 1) :=
⟨list.scanl f b v.to_list, by rw [list.length_scanl, to_list_length]⟩
/-- Providing an empty vector to `scanl` gives the starting value `b : β`. -/
@[simp] lemma scanl_nil : scanl f b nil = b ::ᵥ nil := rfl
/--
The recursive step of `scanl` splits a vector `x ::ᵥ v : vector α (n + 1)`
into the provided starting value `b : β` and the recursed `scanl`
`f b x : β` as the starting value.
This lemma is the `cons` version of `scanl_nth`.
-/
@[simp] lemma scanl_cons (x : α) : scanl f b (x ::ᵥ v) = b ::ᵥ scanl f (f b x) v :=
by simpa only [scanl, to_list_cons]
/--
The underlying `list` of a `vector` after a `scanl` is the `list.scanl`
of the underlying `list` of the original `vector`.
-/
@[simp] lemma scanl_val : ∀ {v : vector α n}, (scanl f b v).val = list.scanl f b v.val
| ⟨l, hl⟩ := rfl
/--
The `to_list` of a `vector` after a `scanl` is the `list.scanl`
of the `to_list` of the original `vector`.
-/
@[simp] lemma to_list_scanl : (scanl f b v).to_list = list.scanl f b v.to_list := rfl
/--
The recursive step of `scanl` splits a vector made up of a single element
`x ::ᵥ nil : vector α 1` into a `vector` of the provided starting value `b : β`
and the mapped `f b x : β` as the last value.
-/
@[simp] lemma scanl_singleton (v : vector α 1) : scanl f b v = b ::ᵥ f b v.head ::ᵥ nil :=
begin
rw [←cons_head_tail v],
simp only [scanl_cons, scanl_nil, cons_head, singleton_tail]
end
/--
The first element of `scanl` of a vector `v : vector α n`,
retrieved via `head`, is the starting value `b : β`.
-/
@[simp] lemma scanl_head : (scanl f b v).head = b :=
begin
cases n,
{ have : v = nil := by simp only [eq_iff_true_of_subsingleton],
simp only [this, scanl_nil, cons_head] },
{ rw ←cons_head_tail v,
simp only [←nth_zero, nth_eq_nth_le, to_list_scanl,
to_list_cons, list.scanl, fin.val_zero', list.nth_le] }
end
/--
For an index `i : fin n`, the `nth` element of `scanl` of a
vector `v : vector α n` at `i.succ`, is equal to the application
function `f : β → α → β` of the `i.cast_succ` element of
`scanl f b v` and `nth v i`.
This lemma is the `nth` version of `scanl_cons`.
-/
@[simp] lemma scanl_nth (i : fin n) :
(scanl f b v).nth i.succ = f ((scanl f b v).nth i.cast_succ) (v.nth i) :=
begin
cases n,
{ exact fin_zero_elim i },
induction n with n hn generalizing b,
{ have i0 : i = 0 := by simp only [eq_iff_true_of_subsingleton],
simpa only [scanl_singleton, i0, nth_zero] },
{ rw [←cons_head_tail v, scanl_cons, nth_cons_succ],
refine fin.cases _ _ i,
{ simp only [nth_zero, scanl_head, fin.cast_succ_zero, cons_head] },
{ intro i',
simp only [hn, fin.cast_succ_fin_succ, nth_cons_succ] } }
end
end scan
def m_of_fn {m} [monad m] {α : Type u} : ∀ {n}, (fin n → m α) → m (vector α n)
| 0 f := pure nil
| (n+1) f := do a ← f 0, v ← m_of_fn (λi, f i.succ), pure (a ::ᵥ v)
theorem m_of_fn_pure {m} [monad m] [is_lawful_monad m] {α} :
∀ {n} (f : fin n → α), @m_of_fn m _ _ _ (λ i, pure (f i)) = pure (of_fn f)
| 0 f := rfl
| (n+1) f := by simp [m_of_fn, @m_of_fn_pure n, of_fn]
def mmap {m} [monad m] {α} {β : Type u} (f : α → m β) :
∀ {n}, vector α n → m (vector β n)
| _ ⟨[], rfl⟩ := pure nil
| _ ⟨a::l, rfl⟩ := do h' ← f a, t' ← mmap ⟨l, rfl⟩, pure (h' ::ᵥ t')
@[simp] theorem mmap_nil {m} [monad m] {α β} (f : α → m β) :
mmap f nil = pure nil := rfl
@[simp] theorem mmap_cons {m} [monad m] {α β} (f : α → m β) (a) :
∀ {n} (v : vector α n), mmap f (a ::ᵥ v) =
do h' ← f a, t' ← mmap f v, pure (h' ::ᵥ t')
| _ ⟨l, rfl⟩ := rfl
/-- Define `C v` by induction on `v : vector α (n + 1)`, a vector of
at least one element.
This function has two arguments: `h0` handles the base case on `C nil`,
and `hs` defines the inductive step using `∀ x : α, C v → C (x ::ᵥ v)`. -/
@[elab_as_eliminator] def induction_on
{α : Type*} {n : ℕ}
{C : Π {n : ℕ}, vector α n → Sort*}
(v : vector α (n + 1))
(h0 : C nil)
(hs : ∀ {n : ℕ} {x : α} {w : vector α n}, C w → C (x ::ᵥ w)) :
C v :=
begin
induction n with n hn,
{ rw ←v.cons_head_tail,
convert hs h0 },
{ rw ←v.cons_head_tail,
apply hs,
apply hn }
end
def to_array : vector α n → array n α
| ⟨xs, h⟩ := cast (by rw h) xs.to_array
section insert_nth
variable {a : α}
def insert_nth (a : α) (i : fin (n+1)) (v : vector α n) : vector α (n+1) :=
⟨v.1.insert_nth i a,
begin
rw [list.length_insert_nth, v.2],
rw [v.2, ← nat.succ_le_succ_iff],
exact i.2
end⟩
lemma insert_nth_val {i : fin (n+1)} {v : vector α n} :
(v.insert_nth a i).val = v.val.insert_nth i.1 a :=
rfl
@[simp] lemma remove_nth_val {i : fin n} :
∀{v : vector α n}, (remove_nth i v).val = v.val.remove_nth i
| ⟨l, hl⟩ := rfl
lemma remove_nth_insert_nth {v : vector α n} {i : fin (n+1)} :
remove_nth i (insert_nth a i v) = v :=
subtype.eq $ list.remove_nth_insert_nth i.1 v.1
lemma remove_nth_insert_nth' {v : vector α (n+1)} :
∀{i : fin (n+1)} {j : fin (n+2)},
remove_nth (j.succ_above i) (insert_nth a j v) = insert_nth a (i.pred_above j) (remove_nth i v)
| ⟨i, hi⟩ ⟨j, hj⟩ :=
begin
dsimp [insert_nth, remove_nth, fin.succ_above, fin.pred_above],
simp only [subtype.mk_eq_mk],
split_ifs,
{ convert (list.insert_nth_remove_nth_of_ge i (j-1) _ _ _).symm,
{ convert (nat.succ_pred_eq_of_pos _).symm, exact lt_of_le_of_lt (zero_le _) h, },
{ apply remove_nth_val, },
{ convert hi, exact v.2, },
{ exact nat.le_pred_of_lt h, }, },
{ convert (list.insert_nth_remove_nth_of_le i j _ _ _).symm,
{ apply remove_nth_val, },
{ convert hi, exact v.2, },
{ simpa using h, }, }
end
lemma insert_nth_comm (a b : α) (i j : fin (n+1)) (h : i ≤ j) :
∀(v : vector α n),
(v.insert_nth a i).insert_nth b j.succ = (v.insert_nth b j).insert_nth a i.cast_succ
| ⟨l, hl⟩ :=
begin
refine subtype.eq _,
simp only [insert_nth_val, fin.coe_succ, fin.cast_succ, fin.val_eq_coe, fin.coe_cast_add],
apply list.insert_nth_comm,
{ assumption },
{ rw hl, exact nat.le_of_succ_le_succ j.2 }
end
end insert_nth
section update_nth
/-- `update_nth v n a` replaces the `n`th element of `v` with `a` -/
def update_nth (v : vector α n) (i : fin n) (a : α) : vector α n :=
⟨v.1.update_nth i.1 a, by rw [list.update_nth_length, v.2]⟩
@[simp] lemma nth_update_nth_same (v : vector α n) (i : fin n) (a : α) :
(v.update_nth i a).nth i = a :=
by cases v; cases i; simp [vector.update_nth, vector.nth_eq_nth_le]
lemma nth_update_nth_of_ne {v : vector α n} {i j : fin n} (h : i ≠ j) (a : α) :
(v.update_nth i a).nth j = v.nth j :=
by cases v; cases i; cases j; simp [vector.update_nth, vector.nth_eq_nth_le,
list.nth_le_update_nth_of_ne (fin.vne_of_ne h)]
lemma nth_update_nth_eq_if {v : vector α n} {i j : fin n} (a : α) :
(v.update_nth i a).nth j = if i = j then a else v.nth j :=
by split_ifs; try {simp *}; try {rw nth_update_nth_of_ne}; assumption
end update_nth
end vector
namespace vector
section traverse
variables {F G : Type u → Type u}
variables [applicative F] [applicative G]
open applicative functor
open list (cons) nat
private def traverse_aux {α β : Type u} (f : α → F β) :
Π (x : list α), F (vector β x.length)
| [] := pure vector.nil
| (x::xs) := vector.cons <$> f x <*> traverse_aux xs
protected def traverse {α β : Type u} (f : α → F β) : vector α n → F (vector β n)
| ⟨v, Hv⟩ := cast (by rw Hv) $ traverse_aux f v
variables [is_lawful_applicative F] [is_lawful_applicative G]
variables {α β γ : Type u}
@[simp] protected lemma traverse_def
(f : α → F β) (x : α) : ∀ (xs : vector α n),
(x ::ᵥ xs).traverse f = cons <$> f x <*> xs.traverse f :=
by rintro ⟨xs, rfl⟩; refl
protected lemma id_traverse : ∀ (x : vector α n), x.traverse id.mk = x :=
begin
rintro ⟨x, rfl⟩, dsimp [vector.traverse, cast],
induction x with x xs IH, {refl},
simp! [IH], refl
end
open function
protected lemma comp_traverse (f : β → F γ) (g : α → G β) : ∀ (x : vector α n),
vector.traverse (comp.mk ∘ functor.map f ∘ g) x =
comp.mk (vector.traverse f <$> vector.traverse g x) :=
by rintro ⟨x, rfl⟩; dsimp [vector.traverse, cast];
induction x with x xs; simp! [cast, *] with functor_norm;
[refl, simp [(∘)]]
protected lemma traverse_eq_map_id {α β} (f : α → β) : ∀ (x : vector α n),
x.traverse (id.mk ∘ f) = id.mk (map f x) :=
by rintro ⟨x, rfl⟩; simp!;
induction x; simp! * with functor_norm; refl
variable (η : applicative_transformation F G)
protected lemma naturality {α β : Type*}
(f : α → F β) : ∀ (x : vector α n),
η (x.traverse f) = x.traverse (@η _ ∘ f) :=
by rintro ⟨x, rfl⟩; simp! [cast];
induction x with x xs IH; simp! * with functor_norm
end traverse
instance : traversable.{u} (flip vector n) :=
{ traverse := @vector.traverse n,
map := λ α β, @vector.map.{u u} α β n }
instance : is_lawful_traversable.{u} (flip vector n) :=
{ id_traverse := @vector.id_traverse n,
comp_traverse := @vector.comp_traverse n,
traverse_eq_map_id := @vector.traverse_eq_map_id n,
naturality := @vector.naturality n,
id_map := by intros; cases x; simp! [(<$>)],
comp_map := by intros; cases x; simp! [(<$>)] }
end vector
|
d48cb8fbfcf69772aa35d353513e24cf5b2b4606 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/data/multiset/nodup.lean | 1b2d7d382837f5ccd3808b98f683accaa9df04b8 | [
"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 | 9,883 | lean | /-
Copyright (c) 2015 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
-/
import data.multiset.bind
import data.multiset.powerset
import data.multiset.range
/-!
# The `nodup` predicate for multisets without duplicate elements.
-/
namespace multiset
open function list
variables {α β γ : Type*} {r : α → α → Prop} {s t : multiset α} {a : α}
/- nodup -/
/-- `nodup s` means that `s` has no duplicates, i.e. the multiplicity of
any element is at most 1. -/
def nodup (s : multiset α) : Prop :=
quot.lift_on s nodup (λ s t p, propext p.nodup_iff)
@[simp] theorem coe_nodup {l : list α} : @nodup α l ↔ l.nodup := iff.rfl
@[simp] theorem nodup_zero : @nodup α 0 := pairwise.nil
@[simp] theorem nodup_cons {a : α} {s : multiset α} : nodup (a ::ₘ s) ↔ a ∉ s ∧ nodup s :=
quot.induction_on s $ λ l, nodup_cons
lemma nodup.cons (m : a ∉ s) (n : nodup s) : nodup (a ::ₘ s) := nodup_cons.2 ⟨m, n⟩
@[simp] theorem nodup_singleton : ∀ a : α, nodup ({a} : multiset α) := nodup_singleton
lemma nodup.of_cons (h : nodup (a ::ₘ s)) : nodup s := (nodup_cons.1 h).2
theorem nodup.not_mem (h : nodup (a ::ₘ s)) : a ∉ s := (nodup_cons.1 h).1
theorem nodup_of_le {s t : multiset α} (h : s ≤ t) : nodup t → nodup s :=
le_induction_on h $ λ l₁ l₂, nodup.sublist
theorem not_nodup_pair : ∀ a : α, ¬ nodup (a ::ₘ a ::ₘ 0) := not_nodup_pair
theorem nodup_iff_le {s : multiset α} : nodup s ↔ ∀ a : α, ¬ a ::ₘ a ::ₘ 0 ≤ s :=
quot.induction_on s $ λ l, nodup_iff_sublist.trans $ forall_congr $ λ a,
not_congr (@repeat_le_coe _ a 2 _).symm
lemma nodup_iff_ne_cons_cons {s : multiset α} : s.nodup ↔ ∀ a t, s ≠ a ::ₘ a ::ₘ t :=
nodup_iff_le.trans
⟨λ h a t s_eq, h a (s_eq.symm ▸ cons_le_cons a (cons_le_cons a (zero_le _))),
λ h a le, let ⟨t, s_eq⟩ := le_iff_exists_add.mp le in
h a t (by rwa [cons_add, cons_add, zero_add] at s_eq )⟩
theorem nodup_iff_count_le_one [decidable_eq α] {s : multiset α} : nodup s ↔ ∀ a, count a s ≤ 1 :=
quot.induction_on s $ λ l, nodup_iff_count_le_one
@[simp] theorem count_eq_one_of_mem [decidable_eq α] {a : α} {s : multiset α}
(d : nodup s) (h : a ∈ s) : count a s = 1 :=
le_antisymm (nodup_iff_count_le_one.1 d a) (count_pos.2 h)
lemma count_eq_of_nodup [decidable_eq α] {a : α} {s : multiset α}
(d : nodup s) : count a s = if a ∈ s then 1 else 0 :=
begin
split_ifs with h,
{ exact count_eq_one_of_mem d h },
{ exact count_eq_zero_of_not_mem h },
end
lemma nodup_iff_pairwise {α} {s : multiset α} : nodup s ↔ pairwise (≠) s :=
quotient.induction_on s $ λ l, (pairwise_coe_iff_pairwise (by exact λ a b, ne.symm)).symm
protected lemma nodup.pairwise : (∀ a ∈ s, ∀ b ∈ s, a ≠ b → r a b) → nodup s → pairwise r s :=
quotient.induction_on s $ assume l h hl, ⟨l, rfl, hl.imp_of_mem $ assume a b ha hb, h a ha b hb⟩
lemma pairwise.forall (H : symmetric r) (hs : pairwise r s) :
∀ ⦃a⦄, a ∈ s → ∀ ⦃b⦄, b ∈ s → a ≠ b → r a b :=
let ⟨l, hl₁, hl₂⟩ := hs in hl₁.symm ▸ hl₂.forall H
theorem nodup_add {s t : multiset α} : nodup (s + t) ↔ nodup s ∧ nodup t ∧ disjoint s t :=
quotient.induction_on₂ s t $ λ l₁ l₂, nodup_append
theorem disjoint_of_nodup_add {s t : multiset α} (d : nodup (s + t)) : disjoint s t :=
(nodup_add.1 d).2.2
lemma nodup.add_iff (d₁ : nodup s) (d₂ : nodup t) : nodup (s + t) ↔ disjoint s t :=
by simp [nodup_add, d₁, d₂]
lemma nodup.of_map (f : α → β) : nodup (map f s) → nodup s :=
quot.induction_on s $ λ l, nodup.of_map f
lemma nodup.map_on {f : α → β} : (∀ x ∈ s, ∀ y ∈ s, f x = f y → x = y) →
nodup s → nodup (map f s) :=
quot.induction_on s $ λ l, nodup.map_on
lemma nodup.map {f : α → β} {s : multiset α} (hf : injective f) : nodup s → nodup (map f s) :=
nodup.map_on (λ x _ y _ h, hf h)
theorem inj_on_of_nodup_map {f : α → β} {s : multiset α} :
nodup (map f s) → ∀ (x ∈ s) (y ∈ s), f x = f y → x = y :=
quot.induction_on s $ λ l, inj_on_of_nodup_map
theorem nodup_map_iff_inj_on {f : α → β} {s : multiset α} (d : nodup s) :
nodup (map f s) ↔ (∀ (x ∈ s) (y ∈ s), f x = f y → x = y) :=
⟨inj_on_of_nodup_map, λ h, d.map_on h⟩
lemma nodup.filter (p : α → Prop) [decidable_pred p] {s} : nodup s → nodup (filter p s) :=
quot.induction_on s $ λ l, nodup.filter p
@[simp] theorem nodup_attach {s : multiset α} : nodup (attach s) ↔ nodup s :=
quot.induction_on s $ λ l, nodup_attach
lemma nodup.pmap {p : α → Prop} {f : Π a, p a → β} {s : multiset α} {H}
(hf : ∀ a ha b hb, f a ha = f b hb → a = b) : nodup s → nodup (pmap f s H) :=
quot.induction_on s (λ l H, nodup.pmap hf) H
instance nodup_decidable [decidable_eq α] (s : multiset α) : decidable (nodup s) :=
quotient.rec_on_subsingleton s $ λ l, l.nodup_decidable
lemma nodup.erase_eq_filter [decidable_eq α] (a : α) {s} : nodup s → s.erase a = filter (≠ a) s :=
quot.induction_on s $ λ l d, congr_arg coe $ d.erase_eq_filter a
lemma nodup.erase [decidable_eq α] (a : α) {l} : nodup l → nodup (l.erase a) :=
nodup_of_le (erase_le _ _)
lemma nodup.mem_erase_iff [decidable_eq α] {a b : α} {l} (d : nodup l) :
a ∈ l.erase b ↔ a ≠ b ∧ a ∈ l :=
by rw [d.erase_eq_filter b, mem_filter, and_comm]
lemma nodup.not_mem_erase [decidable_eq α] {a : α} {s} (h : nodup s) : a ∉ s.erase a :=
λ ha, (h.mem_erase_iff.1 ha).1 rfl
protected lemma nodup.product {t : multiset β} : nodup s → nodup t → nodup (product s t) :=
quotient.induction_on₂ s t $ λ l₁ l₂ d₁ d₂, by simp [d₁.product d₂]
protected lemma nodup.sigma {σ : α → Type*} {t : Π a, multiset (σ a)} :
nodup s → (∀ a, nodup (t a)) → nodup (s.sigma t) :=
quot.induction_on s $ assume l₁,
begin
choose f hf using assume a, quotient.exists_rep (t a),
rw show t = λ a, f a, from (eq.symm $ funext $ λ a, hf a),
simpa using nodup.sigma
end
protected lemma nodup.filter_map (f : α → option β) (H : ∀ a a' b, b ∈ f a → b ∈ f a' → a = a') :
nodup s → nodup (filter_map f s) :=
quot.induction_on s $ λ l, nodup.filter_map H
theorem nodup_range (n : ℕ) : nodup (range n) := nodup_range _
lemma nodup.inter_left [decidable_eq α] (t) : nodup s → nodup (s ∩ t) :=
nodup_of_le $ inter_le_left _ _
lemma nodup.inter_right [decidable_eq α] (s) : nodup t → nodup (s ∩ t) :=
nodup_of_le $ inter_le_right _ _
@[simp] theorem nodup_union [decidable_eq α] {s t : multiset α} :
nodup (s ∪ t) ↔ nodup s ∧ nodup t :=
⟨λ h, ⟨nodup_of_le (le_union_left _ _) h, nodup_of_le (le_union_right _ _) h⟩,
λ ⟨h₁, h₂⟩, nodup_iff_count_le_one.2 $ λ a, by rw [count_union]; exact
max_le (nodup_iff_count_le_one.1 h₁ a) (nodup_iff_count_le_one.1 h₂ a)⟩
@[simp] theorem nodup_powerset {s : multiset α} : nodup (powerset s) ↔ nodup s :=
⟨λ h, (nodup_of_le (map_single_le_powerset _) h).of_map _,
quotient.induction_on s $ λ l h,
by simp; refine (nodup_sublists'.2 h).map_on _ ; exact
λ x sx y sy e,
(h.sublist_ext (mem_sublists'.1 sx) (mem_sublists'.1 sy)).1
(quotient.exact e)⟩
alias nodup_powerset ↔ nodup.of_powerset nodup.powerset
protected lemma nodup.powerset_len {n : ℕ} (h : nodup s) : nodup (powerset_len n s) :=
nodup_of_le (powerset_len_le_powerset _ _) (nodup_powerset.2 h)
@[simp] lemma nodup_bind {s : multiset α} {t : α → multiset β} :
nodup (bind s t) ↔ ((∀a∈s, nodup (t a)) ∧ (s.pairwise (λa b, disjoint (t a) (t b)))) :=
have h₁ : ∀a, ∃l:list β, t a = l, from
assume a, quot.induction_on (t a) $ assume l, ⟨l, rfl⟩,
let ⟨t', h'⟩ := classical.axiom_of_choice h₁ in
have t = λa, t' a, from funext h',
have hd : symmetric (λa b, list.disjoint (t' a) (t' b)), from assume a b h, h.symm,
quot.induction_on s $ by simp [this, list.nodup_bind, pairwise_coe_iff_pairwise hd]
lemma nodup.ext {s t : multiset α} : nodup s → nodup t → (s = t ↔ ∀ a, a ∈ s ↔ a ∈ t) :=
quotient.induction_on₂ s t $ λ l₁ l₂ d₁ d₂, quotient.eq.trans $ perm_ext d₁ d₂
theorem le_iff_subset {s t : multiset α} : nodup s → (s ≤ t ↔ s ⊆ t) :=
quotient.induction_on₂ s t $ λ l₁ l₂ d, ⟨subset_of_le, d.subperm⟩
theorem range_le {m n : ℕ} : range m ≤ range n ↔ m ≤ n :=
(le_iff_subset (nodup_range _)).trans range_subset
theorem mem_sub_of_nodup [decidable_eq α] {a : α} {s t : multiset α} (d : nodup s) :
a ∈ s - t ↔ a ∈ s ∧ a ∉ t :=
⟨λ h, ⟨mem_of_le tsub_le_self h, λ h',
by refine count_eq_zero.1 _ h; rw [count_sub a s t, tsub_eq_zero_iff_le];
exact le_trans (nodup_iff_count_le_one.1 d _) (count_pos.2 h')⟩,
λ ⟨h₁, h₂⟩, or.resolve_right (mem_add.1 $ mem_of_le le_tsub_add h₁) h₂⟩
lemma map_eq_map_of_bij_of_nodup (f : α → γ) (g : β → γ) {s : multiset α} {t : multiset β}
(hs : s.nodup) (ht : t.nodup) (i : Πa∈s, β)
(hi : ∀a ha, i a ha ∈ t) (h : ∀a ha, f a = g (i a ha))
(i_inj : ∀a₁ a₂ ha₁ ha₂, i a₁ ha₁ = i a₂ ha₂ → a₁ = a₂)
(i_surj : ∀b∈t, ∃a ha, b = i a ha) :
s.map f = t.map g :=
have t = s.attach.map (λ x, i x.1 x.2),
from (ht.ext $ (nodup_attach.2 hs).map $
show injective (λ x : {x // x ∈ s}, i x.1 x.2), from λ x y hxy,
subtype.eq $ i_inj x.1 y.1 x.2 y.2 hxy).2
(λ x, by simp only [mem_map, true_and, subtype.exists, eq_comm, mem_attach];
exact ⟨i_surj _, λ ⟨y, hy⟩, hy.snd.symm ▸ hi _ _⟩),
calc s.map f = s.pmap (λ x _, f x) (λ _, id) : by rw [pmap_eq_map]
... = s.attach.map (λ x, f x.1) : by rw [pmap_eq_map_attach]
... = t.map g : by rw [this, multiset.map_map]; exact map_congr rfl (λ x _, h _ _)
end multiset
|
7de7a1cf2b227eb9b3ab9791964ef136eec82fc0 | 6b7c9c6393bac7cb1c64582a1c62597e24f5bb80 | /src/basic/control.lean | 443ad35d85cb4a2cc3550da216972a17321dae3a | [
"Apache-2.0"
] | permissive | alreadydone/lean-gptf | 56a7d9cbd9400af72fb143d60c8774b8cfbc09cb | b4ab1eb2da0178f3dcdc49771d9fed6b50e35d98 | refs/heads/master | 1,679,371,993,063 | 1,614,479,778,000 | 1,614,479,778,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 6,401 | lean | /- Author: E.W.Ayers © 2019.
Some helpers for dealing with monads etc.
-/
import control.monad.writer control.fold
universes u v
section
/- Having a writer with append is really useful! -/
def writer_m (ω : Type) (α : Type) := ω × α
variables {ω : Type} [has_append ω] [has_emptyc ω] {α : Type}
instance writer_m.is_monad : monad (writer_m ω) :=
{ pure := λ α a, (∅, a)
, bind := λ α β ⟨w,a⟩ f, let ⟨w₂,b⟩ := f a in ⟨w ++ w₂, b⟩
}
def writer_m.tell : ω → writer_m ω unit
| x := (x, ())
def writer_m.run : writer_m ω α → ω × α := id
end
namespace writer_t
variables {ω : Type u} {m : Type u → Type v} [monad m] {α β : Type u} [has_emptyc ω] [has_append ω]
instance monad_of_append : monad (writer_t ω m) :=
@writer_t.monad ω m _ ⟨∅⟩ ⟨(++)⟩
instance lift_of_empty : has_monad_lift m (writer_t ω m) :=
⟨λ α, @writer_t.lift _ _ _ _ ⟨∅⟩⟩
end writer_t
def list_writer_t (σ : Type u) := writer_t (free_monoid σ)
namespace list_writer_t
local attribute [reducible] list_writer_t free_monoid
variables {σ : Type u} {m : Type u → Type v} [monad m]
instance : monad (list_writer_t σ m) := by apply_instance
instance : monad_writer (list σ) (list_writer_t σ m) := by apply_instance
end list_writer_t
namespace alternative
section
variables {T S : Type u → Type u} [applicative T] [alternative S]
instance : alternative (T ∘ S) :=
{ pure := λ α x, (pure (pure x) : T (S _)),
failure := λ x, (pure $ failure : T (S _)),
seq := λ α β f x, show T(S β), from pure (<*>) <*> f <*> x,
orelse := λ α a b, show T(S α), from pure (<|>) <*> a <*> b
}
end
variables {T : Type u → Type v} [alternative T] {α β : Type u}
def returnopt : option α → T α
| none := failure
| (some x) := pure x
def optreturn : T α → T (option α)
| t := (some <$> t) <|> (pure none)
def is_ok {T : Type → Type v} [alternative T] {α : Type}: T α → T (bool)
| t := (t *> pure (tt)) <|> pure (ff)
def mguard {T : Type → Type v} [alternative T] [monad T]: T bool → T unit
| c := do b ← c, if b then pure () else failure
variables [monad T]
meta def repeat (t : T α) : T (list α) :=
(pure list.cons <*> t <*> (pure punit.star >>= λ _, repeat)) <|> pure []
end alternative
def except.flip {ε : Type u} {α : Type v} : except ε α → except α ε
| e := except.rec except.ok except.error e
instance monad_except.of_statet {ε σ} {m : Type → Type} [monad m] [monad_except ε m] : monad_except ε (state_t σ m) :=
{ throw := λ α e, state_t.lift $ throw e
, catch := λ α S e, ⟨λ s, catch (state_t.run S s) (λ x, state_t.run (e x) s)⟩ -- [note] alternatively, you could propagate the state.
}
instance monad_except.alt {ε} [inhabited ε] {m : Type → Type} [monad m] [monad_except ε m] : alternative m :=
{ failure := λ α,throw $ inhabited.default ε
, orelse := λ α x y, monad_except.orelse x y
}
def monad_state.hypothetically {m : Type → Type} [monad m] {σ α : Type} [monad_state σ m] : m α → m α
| m := do s ← get, a ← m, put s, pure a
notation `⍐` := monad_lift
namespace interaction_monad
namespace result
variables {σ α β : Type}
protected meta def map (f : α → β) : interaction_monad.result σ α → interaction_monad.result σ β
| (success b s) := success (f b) s
| (exception m p s) := exception m p s
meta def map_state {τ : Type} (f : σ → τ) : result σ α → result τ α
| (success a s) := success a (f s)
| (exception m p s) := exception m p (f s)
meta def state : result σ α → σ
| (success b s) := s
| (exception m p s) := s
meta def get : result σ α → option α
| (success b _) := some b
| (exception _ _ _) := none
meta def as_success : result σ α → option (α × σ)
| (success b s) := some (b,s)
| _ := none
meta def as_exception : result σ α → option (option (unit → format) × option pos × σ)
| (success b s) := none
| (exception m p s) := (m,p,s)
meta def as_except : result σ α → except (option (unit → format) × option pos) α
| (success b s) := except.ok b
| (exception m p s) := except.error $ (m, p)
meta instance {σ} : functor (result σ) := {map := @result.map σ}
end result
meta instance {σ} : monad_state σ (interaction_monad σ) :=
{lift := λ α s x, let ⟨a,x⟩ := s.run x in result.success a x }
meta instance {σ} : alternative (interaction_monad σ) :=
{ failure := @interaction_monad.failed _,
orelse := @interaction_monad_orelse _ }
meta def lift_of_lens {τ σ} (get : τ → σ) (put : σ → τ → τ)
: Π {α}, (interaction_monad σ α) → (interaction_monad τ α)
| α s t := result.map_state (function.swap put $ t) $ s $ get t
meta def has_monad_lift_of_lens {τ σ} (get : τ → σ) (put : σ → τ → τ)
: has_monad_lift (interaction_monad σ) (interaction_monad τ) :=
⟨λ α, lift_of_lens get put⟩
/-- Perform the given tactic but then just keep the result and throw away the state. -/
meta def hypothetically {σ α} : interaction_monad σ α → interaction_monad σ α
| t s := result.map_state (λ _, s) $ t s
meta def get_state_after {σ α}: interaction_monad σ α → interaction_monad σ σ
| t s := let s := result.state $ t s in result.success s s
meta def return_except {ε σ α} [has_to_format ε] : except ε α → interaction_monad σ α
| (except.ok a) := pure a
| (except.error e) := interaction_monad.fail e
meta def run_simple {σ α}: interaction_monad σ α → σ → option (α × σ)
| m s := result.as_success $ m s
/-- If the given tactic fails, trace the failure message. -/
meta def trace_fail {σ α} (tr : format → interaction_monad σ unit) (t : interaction_monad σ α) : (interaction_monad σ α)
| s :=
match t s with
|(interaction_monad.result.exception msg pos _) :=
let msg := ("Exception: ":format) ++ (option.rec_on msg (to_fmt "silent") ($ ())) in
((tr msg) >> t) s
|r := r
end
-- meta def lift_state_except {σ} : Π {α}, interaction_monad σ α → state_t σ (except_t (option (unit → format) × option pos) id) α
-- | m := do
-- s ← get,
-- match m s with
-- | (success b s) := put s *> pure b
-- | (exception m p s) := put s *> throw (m,p)
-- end
end interaction_monad
|
0f5f3a64c121591cf5152604dc61195b2d734e50 | 5ca7b1b12d14c4742e29366312ba2c2ef8201b21 | /src/game/world8/level10.lean | 2c4930bfb333ce819bd954dc8389e71dd8fd1462 | [
"Apache-2.0"
] | permissive | MatthiasHu/natural_number_game | 2e464482ef3001863430b0336133b6697b275ba3 | 2d764f72669ae30861f6a1057fce0257f3e466c4 | refs/heads/master | 1,609,719,110,419 | 1,576,345,737,000 | 1,576,345,737,000 | 240,296,314 | 0 | 0 | Apache-2.0 | 1,581,608,357,000 | 1,581,608,356,000 | null | UTF-8 | Lean | false | false | 1,989 | lean | import game.world8.level9 -- hide
namespace mynat -- hide
/-
# Advanced Addition World
## Level 10: `add_left_eq_zero`
## Important: the definition of `≠`
In Lean, `a ≠ b` is *defined to mean* `(a = b) → false`.
This means that if you see `a ≠ b` you can *literally treat
it as saying* `(a = b) → false`. Computer scientists would
say that these two terms are *definitionally equal*.
The following lemma, $a+b=0\implies b=0$, will be useful in inequality world.
Let me go through the proof, because it introduces several new
concepts:
* `cases b` with `b : mynat`
* `exfalso`
* `apply succ_ne_zero`
We're going to prove $a+b=0\implies b=0$. Here is the
strategy. Each natural number is either `0` or `succ(d)` for
some other natural number `d`. So we can start the proof
with
`cases b with d,`
and then we have two goals, the case `b = 0` (which you can solve easily)
and the case `b = succ(d)`, which looks like this:
```
a d : mynat,
H : a + succ d = 0
⊢ succ d = 0
```
Our goal is impossible to prove. However our hypothesis `H`
is also impossible, meaning that we still have a chance!
First let's see why `H` is impossible. We can
`rw add_succ at H,`
to turn `H` into `H : succ (a + d) = 0`. Because
`succ_ne_zero (a + d)` is a proof that `succ (a + d) ≠ 0`,
it is also a proof of the implication `succ (a + d) = 0 → false`.
Hence `succ_ne_zero (a + d) H` is a proof of `false`!
Unfortunately our goal is not `false`, it's a generic
false statement.
Recall however that the `exfalso` command turns any goal into `false`
(it's logically OK because `false` implies every proposition, true or false).
You can probably take it from here.
-/
/- Lemma
If $a$ and $b$ are natural numbers such that
$$ a + b = 0, $$
then $b = 0$.
-/
lemma add_left_eq_zero (a b : mynat) (H : a + b = 0) : b = 0 :=
begin [nat_num_game]
cases b with d,
{ refl},
{ rw add_succ at H,
exfalso,
apply succ_ne_zero (a + d),
exact H,
},
end
end mynat -- hide
|
e49b67ccc6b7fa580976a58ffb9a40f8eba876eb | 94e33a31faa76775069b071adea97e86e218a8ee | /src/linear_algebra/projective_space/basic.lean | 4be3ed2e0e4a049a9a67161a6b72a93c8ee73530 | [
"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 | 8,248 | lean | /-
Copyright (c) 2022 Adam Topaz. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Adam Topaz
-/
import linear_algebra.finite_dimensional
/-!
# Projective Spaces
This file contains the definition of the projectivization of a vector space over a field,
as well as the bijection between said projectivization and the collection of all one
dimensional subspaces of the vector space.
## Notation
`ℙ K V` is notation for `projectivization K V`, the projectivization of a `K`-vector space `V`.
## Constructing terms of `ℙ K V`.
We have three ways to construct terms of `ℙ K V`:
- `projectivization.mk K v hv` where `v : V` and `hv : v ≠ 0`.
- `projectivization.mk' K v` where `v : { w : V // w ≠ 0 }`.
- `projectivization.mk'' H h` where `H : submodule K V` and `h : finrank H = 1`.
## Other definitions
- For `v : ℙ K V`, `v.submodule` gives the corresponding submodule of `V`.
- `projectivization.equiv_submodule` is the equivalence between `ℙ K V`
and `{ H : submodule K V // finrank H = 1 }`.
- For `v : ℙ K V`, `v.rep : V` is a representative of `v`.
## Projects
Everything in this file can be done for `division_ring`s instead of `field`s, but
this would require a significant refactor of the results from
`linear_algebra.finite_dimensional` and its imports.
-/
variables (K V : Type*) [field K] [add_comm_group V] [module K V]
/-- The setoid whose quotient is the projectivization of `V`. -/
def projectivization_setoid : setoid { v : V // v ≠ 0 } :=
(mul_action.orbit_rel Kˣ V).comap coe
/-- The projectivization of the `K`-vector space `V`.
The notation `ℙ K V` is preferred. -/
@[nolint has_inhabited_instance]
def projectivization := quotient (projectivization_setoid K V)
notation `ℙ` := projectivization
namespace projectivization
variables {V}
/-- Construct an element of the projectivization from a nonzero vector. -/
def mk (v : V) (hv : v ≠ 0) : ℙ K V := quotient.mk' ⟨v,hv⟩
/-- A variant of `projectivization.mk` in terms of a subtype. `mk` is preferred. -/
def mk' (v : { v : V // v ≠ 0 }) : ℙ K V := quotient.mk' v
@[simp] lemma mk'_eq_mk (v : { v : V // v ≠ 0}) :
mk' K v = mk K v v.2 :=
by { dsimp [mk, mk'], congr' 1, simp }
instance [nontrivial V] : nonempty (ℙ K V) :=
let ⟨v, hv⟩ := exists_ne (0 : V) in ⟨mk K v hv⟩
variable {K}
/-- Choose a representative of `v : projectivization K V` in `V`. -/
protected noncomputable def rep (v : ℙ K V) : V := v.out'
lemma rep_nonzero (v : ℙ K V) : v.rep ≠ 0 := v.out'.2
@[simp]
lemma mk_rep (v : ℙ K V) :
mk K v.rep v.rep_nonzero = v :=
by { dsimp [mk, projectivization.rep], simp }
open finite_dimensional
/-- Consider an element of the projectivization as a submodule of `V`. -/
protected def submodule (v : ℙ K V) : submodule K V :=
quotient.lift_on' v (λ v, K ∙ (v : V)) $ begin
rintro ⟨a, ha⟩ ⟨b, hb⟩ ⟨x, (rfl : x • b = a)⟩,
exact (submodule.span_singleton_group_smul_eq _ x _),
end
variable (K)
lemma mk_eq_mk_iff (v w : V) (hv : v ≠ 0) (hw : w ≠ 0) :
mk K v hv = mk K w hw ↔ ∃ (a : Kˣ), a • w = v :=
quotient.eq'
/-- Two nonzero vectors go to the same point in projective space if and only if one is
a scalar multiple of the other. -/
lemma mk_eq_mk_iff' (v w : V) (hv : v ≠ 0) (hw : w ≠ 0) : mk K v hv = mk K w hw ↔
∃ (a : K), a • w = v :=
begin
rw mk_eq_mk_iff K v w hv hw,
split,
{ rintro ⟨a, ha⟩, exact ⟨a, ha⟩ },
{ rintro ⟨a, ha⟩, refine ⟨units.mk0 a (λ c, hv.symm _), ha⟩, rwa [c, zero_smul] at ha }
end
lemma exists_smul_eq_mk_rep
(v : V) (hv : v ≠ 0) : ∃ (a : Kˣ), a • v = (mk K v hv).rep :=
show (projectivization_setoid K V).rel _ _, from quotient.mk_out' ⟨v, hv⟩
variable {K}
/-- An induction principle for `projectivization`.
Use as `induction v using projectivization.ind`. -/
@[elab_as_eliminator]
lemma ind {P : ℙ K V → Prop} (h : ∀ (v : V) (h : v ≠ 0), P (mk K v h)) :
∀ p, P p :=
quotient.ind' $ subtype.rec $ by exact h
@[simp]
lemma submodule_mk (v : V) (hv : v ≠ 0) : (mk K v hv).submodule = K ∙ v := rfl
lemma submodule_eq (v : ℙ K V) : v.submodule = K ∙ v.rep :=
by { conv_lhs { rw ← v.mk_rep }, refl }
lemma finrank_submodule (v : ℙ K V) : finrank K v.submodule = 1 :=
begin
rw submodule_eq,
exact finrank_span_singleton v.rep_nonzero,
end
instance (v : ℙ K V) : finite_dimensional K v.submodule :=
by { rw ← v.mk_rep, change finite_dimensional K (K ∙ v.rep), apply_instance }
lemma submodule_injective : function.injective
(projectivization.submodule : ℙ K V → submodule K V) :=
begin
intros u v h, replace h := le_of_eq h,
simp only [submodule_eq] at h,
rw submodule.le_span_singleton_iff at h,
rw [← mk_rep v, ← mk_rep u],
apply quotient.sound',
obtain ⟨a,ha⟩ := h u.rep (submodule.mem_span_singleton_self _),
have : a ≠ 0 := λ c, u.rep_nonzero (by simpa [c] using ha.symm),
use [units.mk0 a this, ha],
end
variables (K V)
/-- The equivalence between the projectivization and the
collection of subspaces of dimension 1. -/
noncomputable
def equiv_submodule : ℙ K V ≃ { H : submodule K V // finrank K H = 1 } :=
equiv.of_bijective (λ v, ⟨v.submodule, v.finrank_submodule⟩)
begin
split,
{ intros u v h, apply_fun (λ e, e.val) at h,
apply submodule_injective h },
{ rintros ⟨H, h⟩,
rw finrank_eq_one_iff' at h,
obtain ⟨v, hv, h⟩ := h,
have : (v : V) ≠ 0 := λ c, hv (subtype.coe_injective c),
use mk K v this,
symmetry,
ext x, revert x, erw ← set.ext_iff, ext x,
dsimp [-set_like.mem_coe],
rw [submodule.span_singleton_eq_range],
refine ⟨λ hh, _, _⟩,
{ obtain ⟨c,hc⟩ := h ⟨x,hh⟩,
exact ⟨c, congr_arg coe hc⟩ },
{ rintros ⟨c,rfl⟩,
refine submodule.smul_mem _ _ v.2 } }
end
variables {K V}
/-- Construct an element of the projectivization from a subspace of dimension 1. -/
noncomputable
def mk'' (H : _root_.submodule K V) (h : finrank K H = 1) : ℙ K V :=
(equiv_submodule K V).symm ⟨H,h⟩
@[simp]
lemma submodule_mk'' (H : _root_.submodule K V) (h : finrank K H = 1) :
(mk'' H h).submodule = H :=
begin
suffices : (equiv_submodule K V) (mk'' H h) = ⟨H,h⟩, by exact congr_arg coe this,
dsimp [mk''],
simp
end
@[simp]
lemma mk''_submodule (v : ℙ K V) : mk'' v.submodule v.finrank_submodule = v :=
show (equiv_submodule K V).symm (equiv_submodule K V _) = _, by simp
section map
variables {L W : Type*} [field L] [add_comm_group W] [module L W]
/-- An injective semilinear map of vector spaces induces a map on projective spaces. -/
def map {σ : K →+* L} (f : V →ₛₗ[σ] W) (hf : function.injective f) :
ℙ K V → ℙ L W :=
quotient.map' (λ v, ⟨f v, λ c, v.2 (hf (by simp [c]))⟩)
begin
rintros ⟨u,hu⟩ ⟨v,hv⟩ ⟨a,ha⟩,
use units.map σ.to_monoid_hom a,
dsimp at ⊢ ha,
erw [← f.map_smulₛₗ, ha],
end
/-- Mapping with respect to a semilinear map over an isomorphism of fields yields
an injective map on projective spaces. -/
lemma map_injective {σ : K →+* L} {τ : L →+* K} [ring_hom_inv_pair σ τ]
(f : V →ₛₗ[σ] W) (hf : function.injective f) :
function.injective (map f hf) :=
begin
intros u v h,
rw [← u.mk_rep, ← v.mk_rep] at *,
apply quotient.sound',
dsimp [map, mk] at h,
simp only [quotient.eq'] at h,
obtain ⟨a,ha⟩ := h,
use units.map τ.to_monoid_hom a,
dsimp at ⊢ ha,
have : (a : L) = σ (τ a), by rw ring_hom_inv_pair.comp_apply_eq₂,
change (a : L) • f v.rep = f u.rep at ha,
rw [this, ← f.map_smulₛₗ] at ha,
exact hf ha,
end
@[simp]
lemma map_id : map
(linear_map.id : V →ₗ[K] V)
(linear_equiv.refl K V).injective = id :=
by { ext v, induction v using projectivization.ind, refl }
@[simp]
lemma map_comp {F U : Type*} [field F] [add_comm_group U] [module F U]
{σ : K →+* L} {τ : L →+* F} {γ : K →+* F} [ring_hom_comp_triple σ τ γ]
(f : V →ₛₗ[σ] W) (hf : function.injective f)
(g : W →ₛₗ[τ] U) (hg : function.injective g) :
map (g.comp f) (hg.comp hf) = map g hg ∘ map f hf :=
by { ext v, induction v using projectivization.ind, refl }
end map
end projectivization
|
ec8c338d6a9ad668ef5e6fcd92f5e7201f285d45 | 7490bf5d40d31857a58062614642bb5a41c36154 | /predicate_logic/intro_and_elim_rules/exists.lean | b7bd5d37de61f45bf0700a54468df542ef5d3bba | [] | no_license | reesegrayallen/Lean-Discrete-Mathematics | 9f1d6fe1c814cc9264ce868a67adcf5a82566e22 | 00c875284613ea12e0a729f519738aab8599456b | refs/heads/main | 1,674,181,372,629 | 1,606,801,004,000 | 1,606,801,004,000 | 317,387,970 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 5,152 | lean | /-
To prove that (∃ (p : P), Q) we show that there
is a specific value, p, in the context of which
we can prove Q.
-/
/-
Here's a silly example. We want to show that
we can pick some natural number in the context
of which we can construct a proof of 1=1. Of
course it doesn't matter what number we pick
because 1=1 is true in any case. So in the
following example, we pick 524. But any value
will do.
-/
lemma silly : ∃ (n : ℕ), 1 = 1 :=
exists.intro 524 rfl
/-
The identifier, silly, is now bound to a
proof of ∃ (n : ℕ), 1 = 1, and we can see
that this proof is actually an ordered pair,
labelled by the exists.intro constructor, the
first element of which is a specific value of
type P and the second of which is a proof of Q.
-/
#reduce silly
/-
In practice, Q will almost always be a
predicate taking a value of type P. In
this case, ∃ (p : P), Q p asserts that
there is some value, p : P, that makes
the predicate, Q p true. In other words,
∃ (p : P), Q p asserts that there is some
p with propery Q.
-/
axiom Ball : Type -- assume there are Balls
axioms b1 b2 : Ball -- b1 and b2 are balls
axiom Blue : Ball → Prop -- Blue is a property
axiom b1_is_blue : Blue b1 -- b1 is blue
-- Prove there exists a blue ball
example : ∃ (b : Ball), Blue b :=
-- use exists.intro
exists.intro
b1 -- here's the ball we picked
b1_is_blue -- here's a proof it's Blue
/-
Here's another example. We'll define ev to be
a predicate specifying a property of natural
numbers of "being even". Then we'll show that
there exists a number that has this property.
-/
def even : ℕ → bool := λ n, n%2 = 0
example : exists (n : ℕ), even n :=
exists.intro 6 rfl
/-
The elimination rule for ∃ tells us what we
can do with a a proof of an existentially
quanitified proposition.
Suppose for example that we're given a proof
that there exists an even natural number. What
can we deduce from this fact? We can deduce
two things: first, there is a specific number
and *we can give it a name*, such as n, for
which, second, there is a proof, that we can
also name, e.g., pf, that *that specific n*
is even. This is the elimination rule.
It sounds complicated but it's not really.
Compare exists.intro and exists.elim to
and.intro and and.elim. The and.intro rule
takes two proofs and forms a pair. The and
elimination rule takes such a pair and lets
us get back (and give names to) the component
proofs. Similarly, exists.intro forms a pair,
of a value and a proof (usually a proof that
that specific value has some property); and
the exists.elimination rule, given a proof
that such a value exists, let's us then give
names to that value and the associated proof.
*We can then use those two values in building
other proofs*. And, as you might expect, we
bind names to the component elements of a
proof of ∃ (p : P), Q by case analysis, and
specifically by pattern matching.
-/
/-
Example: Assume there are people and a binary
predicate/relation called Likes.
-/
axiom Person : Prop
axiom Likes : Person → Person → Prop
/-
Show that if there exists someone everyone
likes then everyone likes someone.
-/
example : (∃ (p : Person), ∀ (q : Person), Likes q p) →
(∀ (p : Person), ∃ (q : Person), Likes p q):=
λ h : (∃ (p : Person), ∀ (q : Person), Likes q p), -- assume proof of ∃ (n : ℕ), even n
match h with -- destructure this proof
-- there's only one constructor, exists.intro
-- give names to arguments to which it must have been applied
| exists.intro beloved liked_by_all :=
-- now use *these* (now named) values to constructed needed proof
λ anyone,
exists.intro beloved (liked_by_all beloved)
end
example : (∃ (p : Person), ∀ (q : Person), Likes q p) →
(∀ (p : Person), ∃ (q : Person), Likes p q):=
λ person_exists_that_everyone_likes,
match person_exists_that_everyone_likes with
| exists.intro beloved loved_by_all := λ anyone,
_
end
-- exists.intro beloved (loved_by_all beloved )
-- end
/-
Here it is in plain English.
Suppose there's someone everyone likes. Show that everyone
likes someone.
Proof: From the fact that there exists someone that everyone
likes, we can deduce that (1) there is a specific person, who
everyone likes; let's call that person "beloved"; and (2) it
is the case that everyone likes beloved. Now we must show that
everyone likes someone. Pick an arbitrary but specific person,
call this person "anyone". We must show that there is someone
that "anyone" likes. But everyone likes beloved, so "anyone",
in particular, likes "beloved". Note: "anyone" might or might
not like other people, but we can be sure that "anyone" likes
beloved, and all we needed to show was that there is someone
that "anyone" likes. QED.
-/
/-
In Lean, if you already have a proof of some existentially
quantified proposition in your context, do case analysis on
it to assign names to its two components: first a value and
then a proof that that value makes the rest of the proposition
true. By the way, we call such a value a "witness" to the
given proposition.
-/
|
16d50fe8b59fe87ed11bfab82770a954bbc2e32e | 63abd62053d479eae5abf4951554e1064a4c45b4 | /src/number_theory/pythagorean_triples.lean | e7296de04249790d04532e105ef6024d4e9bbcbc | [
"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 | 26,067 | lean | /-
Copyright (c) 2020 Paul van Wamelen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Paul van Wamelen.
-/
import algebra.field
import ring_theory.int.basic
import algebra.group_with_zero_power
import tactic.ring
import tactic.ring_exp
/-!
# Pythagorean Triples
The main result is the classification of pythagorean triples. The final result is for general
pythagorean triples. It follows from the more interesting relatively prime case. We use the
"rational parametrization of the circle" method for the proof. The parametrization maps the point
`(x / z, y / z)` to the slope of the line through `(-1 , 0)` and `(x / z, y / z)`. This quickly
shows that `(x / z, y / z) = (2 * m * n / (m ^ 2 + n ^ 2), (m ^ 2 - n ^ 2) / (m ^ 2 + n ^ 2))` where
`m / n` is the slope. In order to identify numerators and denominators we now need results showing
that these are coprime. This is easy except for the prime 2. In order to deal with that we have to
analyze the parity of `x`, `y`, `m` and `n` and eliminate all the impossible cases. This takes up
the bulk of the proof below.
-/
noncomputable theory
open_locale classical
/-- Three integers `x`, `y`, and `z` form a Pythagorean triple if `x * x + y * y = z * z`. -/
def pythagorean_triple (x y z : ℤ) : Prop := x * x + y * y = z * z
/-- Pythagorean triples are interchangable, i.e `x * x + y * y = y * y + x * x = z * z`.
This comes from additive commutativity. -/
lemma pythagorean_triple_comm {x y z : ℤ} :
(pythagorean_triple x y z) ↔ (pythagorean_triple y x z) :=
by { delta pythagorean_triple, rw add_comm }
/-- The zeroth Pythagorean triple is all zeros. -/
lemma pythagorean_triple.zero : pythagorean_triple 0 0 0 :=
by simp only [pythagorean_triple, zero_mul, zero_add]
namespace pythagorean_triple
variables {x y z : ℤ} (h : pythagorean_triple x y z)
include h
lemma eq : x * x + y * y = z * z := h
@[symm]
lemma symm :
pythagorean_triple y x z :=
by rwa [pythagorean_triple_comm]
/-- A triple is still a triple if you multiply `x`, `y` and `z`
by a constant `k`. -/
lemma mul (k : ℤ) : pythagorean_triple (k * x) (k * y) (k * z) :=
begin
by_cases hk : k = 0,
{ simp only [pythagorean_triple, hk, zero_mul, zero_add], },
{ calc (k * x) * (k * x) + (k * y) * (k * y)
= k ^ 2 * (x * x + y * y) : by ring
... = k ^ 2 * (z * z) : by rw h.eq
... = (k * z) * (k * z) : by ring }
end
omit h
/-- `(k*x, k*y, k*z)` is a Pythagorean triple if and only if
`(x, y, z)` is also a triple. -/
lemma mul_iff (k : ℤ) (hk : k ≠ 0) :
pythagorean_triple (k * x) (k * y) (k * z) ↔ pythagorean_triple x y z :=
begin
refine ⟨_, λ h, h.mul k⟩,
simp only [pythagorean_triple],
intro h,
rw ← mul_left_inj' (mul_ne_zero hk hk),
convert h using 1; ring,
end
include h
/-- A pythogorean triple `x, y, z` is “classified” if there exist integers `k, m, n` such that either
* `x = k * (m ^ 2 - n ^ 2)` and `y = k * (2 * m * n)`, or
* `x = k * (2 * m * n)` and `y = k * (m ^ 2 - n ^ 2)`. -/
@[nolint unused_arguments] def is_classified := ∃ (k m n : ℤ),
((x = k * (m ^ 2 - n ^ 2) ∧ y = k * (2 * m * n))
∨ (x = k * (2 * m * n) ∧ y = k * (m ^ 2 - n ^ 2)))
∧ int.gcd m n = 1
/-- A primitive pythogorean triple `x, y, z` is a pythagorean triple with `x` and `y` coprime.
Such a triple is “primitively classified” if there exist coprime integers `m, n` such that either
* `x = m ^ 2 - n ^ 2` and `y = 2 * m * n`, or
* `x = 2 * m * n` and `y = m ^ 2 - n ^ 2`.
-/
@[nolint unused_arguments] def is_primitive_classified := ∃ (m n : ℤ),
((x = m ^ 2 - n ^ 2 ∧ y = 2 * m * n)
∨ (x = 2 * m * n ∧ y = m ^ 2 - n ^ 2))
∧ int.gcd m n = 1
∧ ((m % 2 = 0 ∧ n % 2 = 1) ∨ (m % 2 = 1 ∧ n % 2 = 0))
lemma mul_is_classified (k : ℤ) (hc : h.is_classified) : (h.mul k).is_classified :=
begin
obtain ⟨l, m, n, ⟨⟨rfl, rfl⟩ | ⟨rfl, rfl⟩, co⟩⟩ := hc,
{ use [k * l, m, n], apply and.intro _ co, left, split; ring },
{ use [k * l, m, n], apply and.intro _ co, right, split; ring },
end
lemma even_odd_of_coprime (hc : int.gcd x y = 1) :
(x % 2 = 0 ∧ y % 2 = 1) ∨ (x % 2 = 1 ∧ y % 2 = 0) :=
begin
cases int.mod_two_eq_zero_or_one x with hx hx;
cases int.mod_two_eq_zero_or_one y with hy hy,
{ -- x even, y even
exfalso,
apply nat.not_coprime_of_dvd_of_dvd (dec_trivial : 1 < 2) _ _ hc,
{ apply int.dvd_nat_abs_of_of_nat_dvd, apply int.dvd_of_mod_eq_zero hx },
{ apply int.dvd_nat_abs_of_of_nat_dvd, apply int.dvd_of_mod_eq_zero hy } },
{ left, exact ⟨hx, hy⟩ }, -- x even, y odd
{ right, exact ⟨hx, hy⟩ }, -- x odd, y even
{ -- x odd, y odd
exfalso,
obtain ⟨x0, y0, rfl, rfl⟩ : ∃ x0 y0, x = x0* 2 + 1 ∧ y = y0 * 2 + 1,
{ cases exists_eq_mul_left_of_dvd (int.dvd_sub_of_mod_eq hx) with x0 hx2,
cases exists_eq_mul_left_of_dvd (int.dvd_sub_of_mod_eq hy) with y0 hy2,
rw sub_eq_iff_eq_add at hx2 hy2, exact ⟨x0, y0, hx2, hy2⟩ },
have hz : (z * z) % 4 = 2,
{ rw show z * z = 4 * (x0 * x0 + x0 + y0 * y0 + y0) + 2, by { rw ← h.eq, ring },
simp only [int.add_mod, int.mul_mod_right, int.mod_mod, zero_add], refl },
have : ∀ (k : ℤ), 0 ≤ k → k < 4 → k * k % 4 ≠ 2 := dec_trivial,
have h4 : (4 : ℤ) ≠ 0 := dec_trivial,
apply this (z % 4) (int.mod_nonneg z h4) (int.mod_lt z h4),
rwa [← int.mul_mod] },
end
lemma gcd_dvd : (int.gcd x y : ℤ) ∣ z :=
begin
by_cases h0 : int.gcd x y = 0,
{ have hx : x = 0, { apply int.nat_abs_eq_zero.mp, apply nat.eq_zero_of_gcd_eq_zero_left h0 },
have hy : y = 0, { apply int.nat_abs_eq_zero.mp, apply nat.eq_zero_of_gcd_eq_zero_right h0 },
have hz : z = 0,
{ simpa only [pythagorean_triple, hx, hy, add_zero, zero_eq_mul, mul_zero, or_self] using h },
simp only [hz, dvd_zero], },
obtain ⟨k, x0, y0, k0, h2, rfl, rfl⟩ :
∃ (k : ℕ) x0 y0, 0 < k ∧ int.gcd x0 y0 = 1 ∧ x = x0 * k ∧ y = y0 * k :=
int.exists_gcd_one' (nat.pos_of_ne_zero h0),
rw [int.gcd_mul_right, h2, int.nat_abs_of_nat, one_mul],
rw [← int.pow_dvd_pow_iff (dec_trivial : 0 < 2), pow_two z, ← h.eq],
rw (by ring : x0 * k * (x0 * k) + y0 * k * (y0 * k) = k ^ 2 * (x0 * x0 + y0 * y0)),
exact dvd_mul_right _ _
end
lemma normalize : pythagorean_triple (x / int.gcd x y) (y / int.gcd x y) (z / int.gcd x y) :=
begin
by_cases h0 : int.gcd x y = 0,
{ have hx : x = 0, { apply int.nat_abs_eq_zero.mp, apply nat.eq_zero_of_gcd_eq_zero_left h0 },
have hy : y = 0, { apply int.nat_abs_eq_zero.mp, apply nat.eq_zero_of_gcd_eq_zero_right h0 },
have hz : z = 0,
{ simpa only [pythagorean_triple, hx, hy, add_zero, zero_eq_mul, mul_zero, or_self] using h },
simp only [hx, hy, hz, int.zero_div], exact zero },
rcases h.gcd_dvd with ⟨z0, rfl⟩,
obtain ⟨k, x0, y0, k0, h2, rfl, rfl⟩ :
∃ (k : ℕ) x0 y0, 0 < k ∧ int.gcd x0 y0 = 1 ∧ x = x0 * k ∧ y = y0 * k :=
int.exists_gcd_one' (nat.pos_of_ne_zero h0),
have hk : (k : ℤ) ≠ 0, { norm_cast, rwa nat.pos_iff_ne_zero at k0 },
rw [int.gcd_mul_right, h2, int.nat_abs_of_nat, one_mul] at h ⊢,
rw [mul_comm x0, mul_comm y0, mul_iff k hk] at h,
rwa [int.mul_div_cancel _ hk, int.mul_div_cancel _ hk, int.mul_div_cancel_left _ hk],
end
lemma is_classified_of_is_primitive_classified (hp : h.is_primitive_classified) :
h.is_classified :=
begin
obtain ⟨m, n, H⟩ := hp,
use [1, m, n],
rcases H with ⟨⟨rfl, rfl⟩ | ⟨rfl, rfl⟩, co, pp⟩;
{ apply and.intro _ co, rw one_mul, rw one_mul, tauto }
end
lemma is_classified_of_normalize_is_primitive_classified (hc : h.normalize.is_primitive_classified) :
h.is_classified :=
begin
convert h.normalize.mul_is_classified (int.gcd x y)
(is_classified_of_is_primitive_classified h.normalize hc);
rw int.mul_div_cancel',
{ exact int.gcd_dvd_left x y },
{ exact int.gcd_dvd_right x y },
{ exact h.gcd_dvd }
end
lemma ne_zero_of_coprime (hc : int.gcd x y = 1) : z ≠ 0 :=
begin
suffices : 0 < z * z, { rintro rfl, norm_num at this },
rw [← h.eq, ← pow_two, ← pow_two],
have hc' : int.gcd x y ≠ 0, { rw hc, exact one_ne_zero },
cases int.ne_zero_of_gcd hc' with hxz hyz,
{ apply lt_add_of_pos_of_le (pow_two_pos_of_ne_zero x hxz) (pow_two_nonneg y) },
{ apply lt_add_of_le_of_pos (pow_two_nonneg x) (pow_two_pos_of_ne_zero y hyz) }
end
lemma is_primitive_classified_of_coprime_of_zero_left (hc : int.gcd x y = 1) (hx : x = 0) :
h.is_primitive_classified :=
begin
subst x,
change nat.gcd 0 (int.nat_abs y) = 1 at hc,
rw [nat.gcd_zero_left (int.nat_abs y)] at hc,
cases int.nat_abs_eq y with hy hy,
{ use [1, 0], rw [hy, hc, int.gcd_zero_right], norm_num },
{ use [0, 1], rw [hy, hc, int.gcd_zero_left], norm_num }
end
lemma coprime_of_coprime (hc : int.gcd x y = 1) : int.gcd y z = 1 :=
begin
by_contradiction H,
obtain ⟨p, hp, hpy, hpz⟩ := nat.prime.not_coprime_iff_dvd.mp H,
apply hp.not_dvd_one,
rw [← hc],
apply nat.dvd_gcd (int.prime.dvd_nat_abs_of_coe_dvd_pow_two hp _ _) hpy,
rw [pow_two, eq_sub_of_add_eq h],
rw [← int.coe_nat_dvd_left] at hpy hpz,
exact dvd_sub (dvd_mul_of_dvd_left (hpz) _) (dvd_mul_of_dvd_left (hpy) _),
end
end pythagorean_triple
section circle_equiv_gen
/-!
### A parametrization of the unit circle
For the classification of pythogorean triples, we will use a parametrization of the unit circle.
-/
variables {K : Type*} [field K]
/-- A parameterization of the unit circle that is useful for classifying Pythagorean triples.
(To be applied in the case where `K = ℚ`.) -/
def circle_equiv_gen (hk : ∀ x : K, 1 + x^2 ≠ 0) :
K ≃ {p : K × K // p.1^2 + p.2^2 = 1 ∧ p.2 ≠ -1} :=
{ to_fun := λ x, ⟨⟨2 * x / (1 + x^2), (1 - x^2) / (1 + x^2)⟩,
by { field_simp [hk x, div_pow], ring },
begin
simp only [ne.def, div_eq_iff (hk x), ←neg_mul_eq_neg_mul, one_mul, neg_add,
sub_eq_add_neg, add_left_inj],
simpa only [eq_neg_iff_add_eq_zero, one_pow] using hk 1,
end⟩,
inv_fun := λ p, (p : K × K).1 / ((p : K × K).2 + 1),
left_inv := λ x,
begin
have h2 : (1 + 1 : K) = 2 := rfl,
have h3 : (2 : K) ≠ 0, { convert hk 1, rw [one_pow 2, h2] },
field_simp [hk x, h2, h3, add_assoc, add_comm, add_sub_cancel'_right, mul_comm],
end,
right_inv := λ ⟨⟨x, y⟩, hxy, hy⟩,
begin
change x ^ 2 + y ^ 2 = 1 at hxy,
have h2 : y + 1 ≠ 0, { apply mt eq_neg_of_add_eq_zero, exact hy },
have h3 : (y + 1) ^ 2 + x ^ 2 = 2 * (y + 1),
{ rw [(add_neg_eq_iff_eq_add.mpr hxy.symm).symm], ring },
have h4 : (2 : K) ≠ 0, { convert hk 1, rw one_pow 2, refl },
simp only [prod.mk.inj_iff, subtype.mk_eq_mk],
split,
{ field_simp [h2, h3, h4], ring },
{ field_simp [h2, h3, h4], rw [← add_neg_eq_iff_eq_add.mpr hxy.symm], ring }
end }
@[simp] lemma circle_equiv_apply (hk : ∀ x : K, 1 + x^2 ≠ 0) (x : K) :
(circle_equiv_gen hk x : K × K) = ⟨2 * x / (1 + x^2), (1 - x^2) / (1 + x^2)⟩ := rfl
@[simp] lemma circle_equiv_symm_apply (hk : ∀ x : K, 1 + x^2 ≠ 0)
(v : {p : K × K // p.1^2 + p.2^2 = 1 ∧ p.2 ≠ -1}) :
(circle_equiv_gen hk).symm v = (v : K × K).1 / ((v : K × K).2 + 1) := rfl
end circle_equiv_gen
private lemma coprime_pow_two_sub_pow_two_add_of_even_odd {m n : ℤ} (h : int.gcd m n = 1)
(hm : m % 2 = 0) (hn : n % 2 = 1) :
int.gcd (m ^ 2 - n ^ 2) (m ^ 2 + n ^ 2) = 1 :=
begin
by_contradiction H,
obtain ⟨p, hp, hp1, hp2⟩ := nat.prime.not_coprime_iff_dvd.mp H,
rw ← int.coe_nat_dvd_left at hp1 hp2,
have h2m : (p : ℤ) ∣ 2 * m ^ 2, { convert dvd_add hp2 hp1, ring },
have h2n : (p : ℤ) ∣ 2 * n ^ 2, { convert dvd_sub hp2 hp1, ring },
have hmc : p = 2 ∨ p ∣ int.nat_abs m, { exact prime_two_or_dvd_of_dvd_two_mul_pow_self_two hp h2m },
have hnc : p = 2 ∨ p ∣ int.nat_abs n, { exact prime_two_or_dvd_of_dvd_two_mul_pow_self_two hp h2n },
by_cases h2 : p = 2,
{ have h3 : (m ^ 2 + n ^ 2) % 2 = 1, { norm_num [pow_two, int.add_mod, int.mul_mod, hm, hn] },
have h4 : (m ^ 2 + n ^ 2) % 2 = 0, { apply int.mod_eq_zero_of_dvd, rwa h2 at hp2 },
rw h4 at h3, exact zero_ne_one h3 },
{ apply hp.not_dvd_one,
rw ← h,
exact nat.dvd_gcd (or.resolve_left hmc h2) (or.resolve_left hnc h2), }
end
private lemma coprime_pow_two_sub_pow_two_add_of_odd_even {m n : ℤ} (h : int.gcd m n = 1)
(hm : m % 2 = 1) (hn : n % 2 = 0):
int.gcd (m ^ 2 - n ^ 2) (m ^ 2 + n ^ 2) = 1 :=
begin
rw [int.gcd, ← int.nat_abs_neg (m ^ 2 - n ^ 2)],
rw [(by ring : -(m ^ 2 - n ^ 2) = n ^ 2 - m ^ 2), add_comm],
apply coprime_pow_two_sub_pow_two_add_of_even_odd _ hn hm, rwa [int.gcd_comm],
end
private lemma coprime_pow_two_sub_mul_of_even_odd {m n : ℤ} (h : int.gcd m n = 1)
(hm : m % 2 = 0) (hn : n % 2 = 1) :
int.gcd (m ^ 2 - n ^ 2) (2 * m * n) = 1 :=
begin
by_contradiction H,
obtain ⟨p, hp, hp1, hp2⟩ := nat.prime.not_coprime_iff_dvd.mp H,
rw ← int.coe_nat_dvd_left at hp1 hp2,
have hnp : ¬ (p : ℤ) ∣ int.gcd m n,
{ rw h, norm_cast, exact mt nat.dvd_one.mp (nat.prime.ne_one hp) },
cases int.prime.dvd_mul hp hp2 with hp2m hpn,
{ rw int.nat_abs_mul at hp2m,
cases (nat.prime.dvd_mul hp).mp hp2m with hp2 hpm,
{ have hp2' : p = 2, { exact le_antisymm (nat.le_of_dvd zero_lt_two hp2) (nat.prime.two_le hp) },
revert hp1, rw hp2',
apply mt int.mod_eq_zero_of_dvd,
norm_num [pow_two, int.sub_mod, int.mul_mod, hm, hn],
},
apply mt (int.dvd_gcd (int.coe_nat_dvd_left.mpr hpm)) hnp,
apply (or_self _).mp, apply int.prime.dvd_mul' hp,
rw (by ring : n * n = - (m ^ 2 - n ^ 2) + m * m),
apply dvd_add (dvd_neg_of_dvd hp1),
exact dvd_mul_of_dvd_left (int.coe_nat_dvd_left.mpr hpm) m
},
rw int.gcd_comm at hnp,
apply mt (int.dvd_gcd (int.coe_nat_dvd_left.mpr hpn)) hnp,
apply (or_self _).mp, apply int.prime.dvd_mul' hp,
rw (by ring : m * m = (m ^ 2 - n ^ 2) + n * n),
apply dvd_add hp1,
exact dvd_mul_of_dvd_left (int.coe_nat_dvd_left.mpr hpn) n
end
private lemma coprime_pow_two_sub_mul_of_odd_even {m n : ℤ} (h : int.gcd m n = 1)
(hm : m % 2 = 1) (hn : n % 2 = 0) :
int.gcd (m ^ 2 - n ^ 2) (2 * m * n) = 1 :=
begin
rw [int.gcd, ← int.nat_abs_neg (m ^ 2 - n ^ 2)],
rw [(by ring : 2 * m * n = 2 * n * m), (by ring : -(m ^ 2 - n ^ 2) = n ^ 2 - m ^ 2)],
apply coprime_pow_two_sub_mul_of_even_odd _ hn hm, rwa [int.gcd_comm]
end
private lemma coprime_pow_two_sub_mul {m n : ℤ} (h : int.gcd m n = 1)
(hmn : (m % 2 = 0 ∧ n % 2 = 1) ∨ (m % 2 = 1 ∧ n % 2 = 0)) :
int.gcd (m ^ 2 - n ^ 2) (2 * m * n) = 1 :=
begin
cases hmn with h1 h2,
{ exact coprime_pow_two_sub_mul_of_even_odd h h1.left h1.right },
{ exact coprime_pow_two_sub_mul_of_odd_even h h2.left h2.right }
end
private lemma coprime_pow_two_sub_pow_two_sum_of_odd_odd {m n : ℤ} (h : int.gcd m n = 1)
(hm : m % 2 = 1) (hn : n % 2 = 1) :
2 ∣ m ^ 2 + n ^ 2
∧ 2 ∣ m ^ 2 - n ^ 2
∧ ((m ^ 2 - n ^ 2) / 2) % 2 = 0
∧ int.gcd ((m ^ 2 - n ^ 2) / 2) ((m ^ 2 + n ^ 2) / 2) = 1 :=
begin
cases exists_eq_mul_left_of_dvd (int.dvd_sub_of_mod_eq hm) with m0 hm2,
cases exists_eq_mul_left_of_dvd (int.dvd_sub_of_mod_eq hn) with n0 hn2,
rw sub_eq_iff_eq_add at hm2 hn2, subst m, subst n,
have h1 : (m0 * 2 + 1) ^ 2 + (n0 * 2 + 1) ^ 2 = 2 * (2 * (m0 ^ 2 + n0 ^ 2 + m0 + n0) + 1),
by ring_exp,
have h2 : (m0 * 2 + 1) ^ 2 - (n0 * 2 + 1) ^ 2 = 2 * (2 * (m0 ^ 2 - n0 ^ 2 + m0 - n0)),
by ring_exp,
have h3 : ((m0 * 2 + 1) ^ 2 - (n0 * 2 + 1) ^ 2) / 2 % 2 = 0,
{ rw [h2, int.mul_div_cancel_left, int.mul_mod_right], exact dec_trivial },
refine ⟨⟨_, h1⟩, ⟨_, h2⟩, h3, _⟩,
have h20 : (2:ℤ) ≠ 0 := dec_trivial,
rw [h1, h2, int.mul_div_cancel_left _ h20, int.mul_div_cancel_left _ h20],
by_contra h4,
obtain ⟨p, hp, hp1, hp2⟩ := nat.prime.not_coprime_iff_dvd.mp h4,
apply hp.not_dvd_one,
rw ← h,
rw ← int.coe_nat_dvd_left at hp1 hp2,
apply nat.dvd_gcd,
{ apply int.prime.dvd_nat_abs_of_coe_dvd_pow_two hp,
convert dvd_add hp1 hp2, ring_exp },
{ apply int.prime.dvd_nat_abs_of_coe_dvd_pow_two hp,
convert dvd_sub hp2 hp1, ring_exp },
end
namespace pythagorean_triple
variables {x y z : ℤ} (h : pythagorean_triple x y z)
include h
lemma is_primitive_classified_aux (hc : x.gcd y = 1) (hzpos : 0 < z)
{m n : ℤ} (hm2n2 : 0 < m ^ 2 + n ^ 2)
(hv2 : (x : ℚ) / z = 2 * m * n / (m ^ 2 + n ^ 2))
(hw2 : (y : ℚ) / z = (m ^ 2 - n ^ 2) / (m ^ 2 + n ^ 2))
(H : int.gcd (m ^ 2 - n ^ 2) (m ^ 2 + n ^ 2) = 1)
(co : int.gcd m n = 1)
(pp : (m % 2 = 0 ∧ n % 2 = 1) ∨ (m % 2 = 1 ∧ n % 2 = 0)):
h.is_primitive_classified :=
begin
have hz : z ≠ 0, apply ne_of_gt hzpos,
have h2 : y = m ^ 2 - n ^ 2 ∧ z = m ^ 2 + n ^ 2,
{ apply rat.div_int_inj hzpos hm2n2 (h.coprime_of_coprime hc) H, rw [hw2], norm_cast },
use [m, n], apply and.intro _ (and.intro co pp), right,
refine ⟨_, h2.left⟩,
rw [← rat.coe_int_inj _ _, ← div_left_inj' ((mt (rat.coe_int_inj z 0).mp) hz), hv2, h2.right],
norm_cast
end
theorem is_primitive_classified_of_coprime_of_odd_of_pos
(hc : int.gcd x y = 1) (hyo : y % 2 = 1) (hzpos : 0 < z) :
h.is_primitive_classified :=
begin
by_cases h0 : x = 0, { exact h.is_primitive_classified_of_coprime_of_zero_left hc h0 },
let v := (x : ℚ) / z,
let w := (y : ℚ) / z,
have hz : z ≠ 0, apply ne_of_gt hzpos,
have hq : v ^ 2 + w ^ 2 = 1,
{ field_simp [hz, pow_two], norm_cast, exact h },
have hvz : v ≠ 0, { field_simp [hz], exact h0 },
have hw1 : w ≠ -1,
{ contrapose! hvz with hw1, rw [hw1, neg_square, one_pow, add_left_eq_self] at hq, exact pow_eq_zero hq, },
have hQ : ∀ x : ℚ, 1 + x^2 ≠ 0,
{ intro q, apply ne_of_gt, exact lt_add_of_pos_of_le zero_lt_one (pow_two_nonneg q) },
have hp : (⟨v, w⟩ : ℚ × ℚ) ∈ {p : ℚ × ℚ | p.1^2 + p.2^2 = 1 ∧ p.2 ≠ -1} := ⟨hq, hw1⟩,
let q := (circle_equiv_gen hQ).symm ⟨⟨v, w⟩, hp⟩,
have ht4 : v = 2 * q / (1 + q ^ 2) ∧ w = (1 - q ^ 2) / (1 + q ^ 2),
{ apply prod.mk.inj,
have := ((circle_equiv_gen hQ).apply_symm_apply ⟨⟨v, w⟩, hp⟩).symm,
exact congr_arg subtype.val this, },
let m := (q.denom : ℤ),
let n := q.num,
have hm0 : m ≠ 0, { norm_cast, apply rat.denom_ne_zero q },
have hq2 : q = n / m, { rw [int.cast_coe_nat], exact (rat.cast_id q).symm },
have hm2n2 : 0 < m ^ 2 + n ^ 2,
{ apply lt_add_of_pos_of_le _ (pow_two_nonneg n),
exact lt_of_le_of_ne (pow_two_nonneg m) (ne.symm (pow_ne_zero 2 hm0)) },
have hw2 : w = (m ^ 2 - n ^ 2) / (m ^ 2 + n ^ 2),
{ rw [ht4.2, hq2], field_simp [hm2n2, (rat.denom_ne_zero q)] },
have hm2n20 : (m : ℚ) ^ 2 + (n : ℚ) ^ 2 ≠ 0,
{ norm_cast, simpa only [int.coe_nat_pow] using ne_of_gt hm2n2 },
have hv2 : v = 2 * m * n / (m ^ 2 + n ^ 2),
{ apply eq.symm, apply (div_eq_iff hm2n20).mpr, rw [ht4.1], field_simp [hQ q],
rw [hq2] {occs := occurrences.pos [2, 3]}, field_simp [rat.denom_ne_zero q], ring },
have hnmcp : int.gcd n m = 1 := q.cop,
have hmncp : int.gcd m n = 1, { rw int.gcd_comm, exact hnmcp },
cases int.mod_two_eq_zero_or_one m with hm2 hm2;
cases int.mod_two_eq_zero_or_one n with hn2 hn2,
{ -- m even, n even
exfalso,
have h1 : 2 ∣ (int.gcd n m : ℤ),
{ exact int.dvd_gcd (int.dvd_of_mod_eq_zero hn2) (int.dvd_of_mod_eq_zero hm2) },
rw hnmcp at h1, revert h1, norm_num },
{ -- m even, n odd
apply h.is_primitive_classified_aux hc hzpos hm2n2 hv2 hw2 _ hmncp,
{ apply or.intro_left, exact and.intro hm2 hn2 },
{ apply coprime_pow_two_sub_pow_two_add_of_even_odd hmncp hm2 hn2 } },
{ -- m odd, n even
apply h.is_primitive_classified_aux hc hzpos hm2n2 hv2 hw2 _ hmncp,
{ apply or.intro_right, exact and.intro hm2 hn2 },
apply coprime_pow_two_sub_pow_two_add_of_odd_even hmncp hm2 hn2 },
{ -- m odd, n odd
exfalso,
have h1 : 2 ∣ m ^ 2 + n ^ 2 ∧ 2 ∣ m ^ 2 - n ^ 2
∧ ((m ^ 2 - n ^ 2) / 2) % 2 = 0 ∧ int.gcd ((m ^ 2 - n ^ 2) / 2) ((m ^ 2 + n ^ 2) / 2) = 1,
{ exact coprime_pow_two_sub_pow_two_sum_of_odd_odd hmncp hm2 hn2 },
have h2 : y = (m ^ 2 - n ^ 2) / 2 ∧ z = (m ^ 2 + n ^ 2) / 2,
{ apply rat.div_int_inj hzpos _ (h.coprime_of_coprime hc) h1.2.2.2,
{ show w = _, rw [←rat.mk_eq_div, ←(rat.div_mk_div_cancel_left (by norm_num : (2 : ℤ) ≠ 0))],
rw [int.div_mul_cancel h1.1, int.div_mul_cancel h1.2.1, hw2], norm_cast },
{ apply (mul_lt_mul_right (by norm_num : 0 < (2 : ℤ))).mp,
rw [int.div_mul_cancel h1.1, zero_mul], exact hm2n2 } },
rw [h2.1, h1.2.2.1] at hyo,
revert hyo,
norm_num }
end
theorem is_primitive_classified_of_coprime_of_pos (hc : int.gcd x y = 1) (hzpos : 0 < z):
h.is_primitive_classified :=
begin
cases h.even_odd_of_coprime hc with h1 h2,
{ exact (h.is_primitive_classified_of_coprime_of_odd_of_pos hc h1.right hzpos) },
rw int.gcd_comm at hc,
obtain ⟨m, n, H⟩ := (h.symm.is_primitive_classified_of_coprime_of_odd_of_pos hc h2.left hzpos),
use [m, n], tauto
end
theorem is_primitive_classified_of_coprime (hc : int.gcd x y = 1) : h.is_primitive_classified :=
begin
by_cases hz : 0 < z,
{ exact h.is_primitive_classified_of_coprime_of_pos hc hz },
have h' : pythagorean_triple x y (-z),
{ simpa [pythagorean_triple, neg_mul_neg] using h.eq, },
apply h'.is_primitive_classified_of_coprime_of_pos hc,
apply lt_of_le_of_ne _ (h'.ne_zero_of_coprime hc).symm,
exact le_neg.mp (not_lt.mp hz)
end
theorem classified : h.is_classified :=
begin
by_cases h0 : int.gcd x y = 0,
{ have hx : x = 0, { apply int.nat_abs_eq_zero.mp, apply nat.eq_zero_of_gcd_eq_zero_left h0 },
have hy : y = 0, { apply int.nat_abs_eq_zero.mp, apply nat.eq_zero_of_gcd_eq_zero_right h0 },
use [0, 1, 0], norm_num [hx, hy], },
apply h.is_classified_of_normalize_is_primitive_classified,
apply h.normalize.is_primitive_classified_of_coprime,
apply int.gcd_div_gcd_div_gcd (nat.pos_of_ne_zero h0),
end
omit h
theorem coprime_classification :
pythagorean_triple x y z ∧ int.gcd x y = 1 ↔
∃ m n, ((x = m ^ 2 - n ^ 2 ∧ y = 2 * m * n) ∨
(x = 2 * m * n ∧ y = m ^ 2 - n ^ 2))
∧ (z = m ^ 2 + n ^ 2 ∨ z = - (m ^ 2 + n ^ 2))
∧ int.gcd m n = 1
∧ ((m % 2 = 0 ∧ n % 2 = 1) ∨ (m % 2 = 1 ∧ n % 2 = 0)) :=
begin
split,
{ intro h,
obtain ⟨m, n, H⟩ := h.left.is_primitive_classified_of_coprime h.right,
use [m, n],
rcases H with ⟨⟨rfl, rfl⟩ | ⟨rfl, rfl⟩, co, pp⟩,
{ refine ⟨or.inl ⟨rfl, rfl⟩, _, co, pp⟩,
have : z ^ 2 = (m ^ 2 + n ^ 2) ^ 2,
{ rw [pow_two, ← h.left.eq], ring },
simpa using eq_or_eq_neg_of_pow_two_eq_pow_two _ _ this },
{ refine ⟨or.inr ⟨rfl, rfl⟩, _, co, pp⟩,
have : z ^ 2 = (m ^ 2 + n ^ 2) ^ 2,
{ rw [pow_two, ← h.left.eq], ring },
simpa using eq_or_eq_neg_of_pow_two_eq_pow_two _ _ this } },
{ delta pythagorean_triple,
rintro ⟨m, n, ⟨rfl, rfl⟩ | ⟨rfl, rfl⟩, rfl | rfl, co, pp⟩;
{ split, { ring }, exact coprime_pow_two_sub_mul co pp }
<|>
{ split, { ring }, rw int.gcd_comm, exact coprime_pow_two_sub_mul co pp } }
end
/-- by assuming `x` is odd and `z` is positive we get a slightly more precise classification of
the pythagorean triple `x ^ 2 + y ^ 2 = z ^ 2`-/
theorem coprime_classification' {x y z : ℤ} (h : pythagorean_triple x y z)
(h_coprime : int.gcd x y = 1) (h_parity : x % 2 = 1) (h_pos : 0 < z) :
∃ m n, x = m ^ 2 - n ^ 2
∧ y = 2 * m * n
∧ z = m ^ 2 + n ^ 2
∧ int.gcd m n = 1
∧ ((m % 2 = 0 ∧ n % 2 = 1) ∨ (m % 2 = 1 ∧ n % 2 = 0))
∧ 0 ≤ m :=
begin
obtain ⟨m, n, ht1, ht2, ht3, ht4⟩ :=
pythagorean_triple.coprime_classification.mp (and.intro h h_coprime),
cases le_or_lt 0 m with hm hm,
{ use [m, n],
cases ht1 with h_odd h_even,
{ apply and.intro h_odd.1,
apply and.intro h_odd.2,
cases ht2 with h_pos h_neg,
{ apply and.intro h_pos (and.intro ht3 (and.intro ht4 hm)) },
{ exfalso, revert h_pos, rw h_neg,
exact imp_false.mpr (not_lt.mpr (neg_nonpos.mpr (add_nonneg (pow_two_nonneg m)
(pow_two_nonneg n)))) } },
exfalso,
rcases h_even with ⟨rfl, -⟩,
rw [mul_assoc, int.mul_mod_right] at h_parity,
exact zero_ne_one h_parity },
{ use [-m, -n],
cases ht1 with h_odd h_even,
{ rw [neg_square m],
rw [neg_square n],
apply and.intro h_odd.1,
split, { rw h_odd.2, ring },
cases ht2 with h_pos h_neg,
{ apply and.intro h_pos,
split,
{ delta int.gcd, rw [int.nat_abs_neg, int.nat_abs_neg], exact ht3 },
{ rw [int.neg_mod_two, int.neg_mod_two],
apply and.intro ht4, linarith } },
{ exfalso, revert h_pos, rw h_neg,
exact imp_false.mpr (not_lt.mpr (neg_nonpos.mpr (add_nonneg (pow_two_nonneg m)
(pow_two_nonneg n)))) } },
exfalso,
rcases h_even with ⟨rfl, -⟩,
rw [mul_assoc, int.mul_mod_right] at h_parity,
exact zero_ne_one h_parity }
end
theorem classification :
pythagorean_triple x y z ↔
∃ k m n, ((x = k * (m ^ 2 - n ^ 2) ∧ y = k * (2 * m * n)) ∨
(x = k * (2 * m * n) ∧ y = k * (m ^ 2 - n ^ 2)))
∧ (z = k * (m ^ 2 + n ^ 2) ∨ z = - k * (m ^ 2 + n ^ 2)) :=
begin
split,
{ intro h,
obtain ⟨k, m, n, H⟩ := h.classified,
use [k, m, n],
rcases H with ⟨rfl, rfl⟩ | ⟨rfl, rfl⟩,
{ refine ⟨or.inl ⟨rfl, rfl⟩, _⟩,
have : z ^ 2 = (k * (m ^ 2 + n ^ 2)) ^ 2,
{ rw [pow_two, ← h.eq], ring },
simpa using eq_or_eq_neg_of_pow_two_eq_pow_two _ _ this },
{ refine ⟨or.inr ⟨rfl, rfl⟩, _⟩,
have : z ^ 2 = (k * (m ^ 2 + n ^ 2)) ^ 2,
{ rw [pow_two, ← h.eq], ring },
simpa using eq_or_eq_neg_of_pow_two_eq_pow_two _ _ this } },
{ rintro ⟨k, m, n, ⟨rfl, rfl⟩ | ⟨rfl, rfl⟩, rfl | rfl⟩;
delta pythagorean_triple; ring }
end
end pythagorean_triple
|
8983dbe863d9b7e677c67a64b801a79409509183 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/measure_theory/integral/interval_average.lean | 635fb91aefdba7150481216f3f8756b2c3cff63b | [
"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 | 1,987 | lean | /-
Copyright (c) 2022 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import analysis.convex.integral
import measure_theory.integral.interval_integral
/-!
# Integral average over an interval
In this file we introduce notation `⨍ x in a..b, f x` for the average `⨍ x in Ι a b, f x` of `f`
over the interval `Ι a b = set.Ioc (min a b) (max a b)` w.r.t. the Lebesgue measure, then prove
formulas for this average:
* `interval_average_eq`: `⨍ x in a..b, f x = (b - a)⁻¹ • ∫ x in a..b, f x`;
* `interval_average_eq_div`: `⨍ x in a..b, f x = (∫ x in a..b, f x) / (b - a)`.
We also prove that `⨍ x in a..b, f x = ⨍ x in b..a, f x`, see `interval_average_symm`.
## Notation
`⨍ x in a..b, f x`: average of `f` over the interval `Ι a b` w.r.t. the Lebesgue measure.
-/
open measure_theory set topological_space
open_locale interval
variables {E : Type*} [normed_add_comm_group E] [normed_space ℝ E] [complete_space E]
notation `⨍` binders ` in ` a `..` b `, `
r:(scoped:60 f, average (measure.restrict volume (Ι a b)) f) := r
lemma interval_average_symm (f : ℝ → E) (a b : ℝ) : ⨍ x in a..b, f x = ⨍ x in b..a, f x :=
by rw [set_average_eq, set_average_eq, interval_oc_swap]
lemma interval_average_eq (f : ℝ → E) (a b : ℝ) : ⨍ x in a..b, f x = (b - a)⁻¹ • ∫ x in a..b, f x :=
begin
cases le_or_lt a b with h h,
{ rw [set_average_eq, interval_oc_of_le h, real.volume_Ioc, interval_integral.integral_of_le h,
ennreal.to_real_of_real (sub_nonneg.2 h)] },
{ rw [set_average_eq, interval_oc_of_lt h, real.volume_Ioc, interval_integral.integral_of_ge h.le,
ennreal.to_real_of_real (sub_nonneg.2 h.le), smul_neg, ← neg_smul, ← inv_neg, neg_sub] }
end
lemma interval_average_eq_div (f : ℝ → ℝ) (a b : ℝ) :
⨍ x in a..b, f x = (∫ x in a..b, f x) / (b - a) :=
by rw [interval_average_eq, smul_eq_mul, div_eq_inv_mul]
|
ce8a7c2c9409098fa53c4506cc9b1a814d5725b2 | ae1e94c332e17c7dc7051ce976d5a9eebe7ab8a5 | /tests/lean/run/newfrontend1.lean | 5e4c3a1af9d94167296910ff29229f0939f116b2 | [
"Apache-2.0"
] | permissive | dupuisf/lean4 | d082d13b01243e1de29ae680eefb476961221eef | 6a39c65bd28eb0e28c3870188f348c8914502718 | refs/heads/master | 1,676,948,755,391 | 1,610,665,114,000 | 1,610,665,114,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 8,777 | lean | def x := 1
#check x
variables {α : Type}
def f (a : α) : α :=
a
def tst (xs : List Nat) : Nat :=
xs.foldl (init := 10) (· + ·)
#check tst [1, 2, 3]
#check fun x y : Nat => x + y
#check tst
#check (fun stx => if True then let e := stx; Pure.pure e else Pure.pure stx : Nat → Id Nat)
#check let x : Nat := 1; x
def foo (a : Nat) (b : Nat := 10) (c : Bool := Bool.true) : Nat :=
a + b
set_option pp.all true
#check foo 1
#check foo 3 (c := false)
def Nat.boo (a : Nat) :=
succ a -- succ here is resolved as `Nat.succ`.
#check Nat.boo
#check true
-- apply is still a valid identifier name
def apply := "hello"
#check apply
theorem simple1 (x y : Nat) (h : x = y) : x = y :=
by {
assumption
}
theorem simple2 (x y : Nat) : x = y → x = y :=
by {
intro h;
assumption
}
syntax "intro2" : tactic
macro_rules
| `(tactic| intro2) => `(tactic| intro; intro )
theorem simple3 (x y : Nat) : x = x → x = y → x = y :=
by {
intro2;
assumption
}
macro "intro3" : tactic => `(intro; intro; intro)
macro "check2" x:term : command => `(#check $x #check $x)
macro "foo" x:term "," y:term : term => `($x + $y + $x)
set_option pp.all false
check2 0+1
check2 foo 0,1
theorem simple4 (x y : Nat) : y = y → x = x → x = y → x = y :=
by {
intro3;
assumption
}
theorem simple5 (x y z : Nat) : y = z → x = x → x = y → x = z :=
by {
intro h1; intro _; intro h3;
exact Eq.trans h3 h1
}
theorem simple6 (x y z : Nat) : y = z → x = x → x = y → x = z :=
by {
intro h1; intro _; intro h3;
refine Eq.trans ?_ h1;
assumption
}
theorem simple7 (x y z : Nat) : y = z → x = x → x = y → x = z :=
by {
intro h1; intro _; intro h3;
refine! Eq.trans ?pre ?post;
exact y;
{ exact h3 }
{ exact h1 }
}
theorem simple8 (x y z : Nat) : y = z → x = x → x = y → x = z := by
intro h1; intro _; intro h3
refine! Eq.trans ?pre ?post
case post => exact h1
case pre => exact h3
theorem simple9 (x y z : Nat) : y = z → x = x → x = y → x = z := by
intros h1 _ h3
traceState
focus
refine! Eq.trans ?pre ?post
first
| exact h1
assumption
| exact y
exact h3
assumption
theorem simple9b (x y z : Nat) : y = z → x = x → x = y → x = z := by
intros h1 _ h3
traceState
focus
refine! Eq.trans ?pre ?post
first
| exact h1
| exact y; exact h3
assumption
theorem simple9c (x y z : Nat) : y = z → x = x → x = y → x = z := by
intros h1 _ h3
solve
| exact h1
| refine! Eq.trans ?pre ?post; exact y; exact h3; assumption
| exact h3
theorem simple9d (x y z : Nat) : y = z → x = x → x = y → x = z := by
intros h1 _ h3
refine! Eq.trans ?pre ?post
solve
| exact h1
| exact y
| exact h3
solve
| exact h1
| exact h3
solve
| exact h1
| assumption
namespace Foo
def Prod.mk := 1
#check (⟨2, 3⟩ : Prod _ _)
end Foo
theorem simple10 (x y z : Nat) : y = z → x = x → x = y → x = z :=
by {
intro h1; intro h2; intro h3;
skip;
apply Eq.trans;
exact h3;
assumption
}
theorem simple11 (x y z : Nat) : y = z → x = x → x = y → x = z :=
by {
intro h1; intro h2; intro h3;
apply @Eq.trans;
traceState;
exact h3;
assumption
}
theorem simple12 (x y z : Nat) : y = z → x = x → x = y → x = z :=
by {
intro h1; intro h2; intro h3;
apply @Eq.trans;
try exact h1; -- `exact h1` fails
traceState;
try exact h3;
traceState;
try exact h1;
}
theorem simple13 (x y z : Nat) : y = z → x = x → x = y → x = z := by
intros h1 h2 h3
traceState
apply @Eq.trans
case b => exact y
traceState
repeat assumption
theorem simple13b (x y z : Nat) : y = z → x = x → x = y → x = z := by {
intros h1 h2 h3;
traceState;
apply @Eq.trans;
case b => exact y;
traceState;
repeat assumption
}
theorem simple14 (x y z : Nat) : y = z → x = x → x = y → x = z := by
intros
apply @Eq.trans
case b => exact y
repeat assumption
theorem simple15 (x y z : Nat) : y = z → x = x → x = y → x = z :=
by {
intros h1 h2 h3;
revert y;
intros y h1 h3;
apply Eq.trans;
exact h3;
exact h1
}
theorem simple16 (x y z : Nat) : y = z → x = x → x = y → x = z :=
by {
intros h1 h2 h3;
try clear x; -- should fail
clear h2;
traceState;
apply Eq.trans;
exact h3;
exact h1
}
macro "blabla" : tactic => `(assumption)
-- Tactic head symbols do not become reserved words
def blabla := 100
#check blabla
theorem simple17 (x : Nat) (h : x = 0) : x = 0 :=
by blabla
theorem simple18 (x : Nat) (h : x = 0) : x = 0 :=
by blabla
theorem simple19 (x y : Nat) (h₁ : x = 0) (h₂ : x = y) : y = 0 :=
by subst x; subst y; exact rfl
theorem tstprec1 (x y z : Nat) : x + y * z = x + (y * z) :=
rfl
theorem tstprec2 (x y z : Nat) : y * z + x = (y * z) + x :=
rfl
set_option pp.all true
#check fun {α} (a : α) => a
#check @(fun α (a : α) => a)
#check
let myid := fun {α} (a : α) => a;
myid [myid 1]
-- In the following example, we need `@` otherwise we will try to insert mvars for α and [Add α],
-- and will fail to generate instance for [Add α]
#check @(fun α (s : Add α) (a : α) => a + a)
def g1 {α} (a₁ a₂ : α) {β} (b : β) : α × α × β :=
(a₁, a₂, b)
def id1 : {α : Type} → α → α :=
fun x => x
def listId : List ({α : Type} → α → α) :=
(fun x => x) :: []
def id2 : {α : Type} → α → α :=
@(fun α (x : α) => id1 x)
def id3 : {α : Type} → α → α :=
@(fun α x => id1 x)
def id4 : {α : Type} → α → α :=
fun x => id1 x
def id5 : {α : Type} → α → α :=
fun {α} x => id1 x
def id6 : {α : Type} → α → α :=
@(fun {α} x => id1 x)
def id7 : {α : Type} → α → α :=
fun {α} x => @id α x
def id8 : {α : Type} → α → α :=
fun {α} x => id (@id α x)
def altTst1 {m σ} [Alternative m] [Monad m] : Alternative (StateT σ m) :=
⟨StateT.failure, StateT.orElse⟩
def altTst2 {m σ} [Alternative m] [Monad m] : Alternative (StateT σ m) :=
⟨@(fun α => StateT.failure), @(fun α => StateT.orElse)⟩
def altTst3 {m σ} [Alternative m] [Monad m] : Alternative (StateT σ m) :=
⟨fun {α} => StateT.failure, fun {α} => StateT.orElse⟩
#check_failure 1 + true
/-
universes u v
/-
MonadFunctorT.{u ?M_1 v} (λ (β : Type u), m α) (λ (β : Type u), m' α) n n'
-/
set_option pp.raw.maxDepth 100
set_option trace.Elab true
def adapt {m m' σ σ'} {n n' : Type → Type} [MonadFunctor m m' n n'] [MonadStateAdapter σ σ' m m'] : MonadStateAdapter σ σ' n n' :=
⟨fun split join => monadMap (adaptState split join : m α → m' α)⟩
-/
syntax "fn" (term:max)+ "=>" term : term
macro_rules
| `(fn $xs* => $b) => `(fun $xs* => $b)
set_option pp.all false
#check fn x => x+1
#check fn α (a : α) => a
def tst1 : {α : Type} → α → α :=
@(fn α a => a)
#check @tst1
syntax ident "==>" term : term
syntax "{" ident "}" "==>" term : term
macro_rules
| `($x:ident ==> $b) => `(fn $x => $b)
| `({$x:ident} ==> $b) => `(fun {$x:ident} => $b)
#check x ==> x+1
def tst2a : {α : Type} → α → α :=
@(α ==> a ==> a)
def tst2b : {α : Type} → α → α :=
{α} ==> a ==> a
#check @tst2a
#check @tst2b
def tst3a : {α : Type} → {β : Type} → α → β → α × β :=
@(α ==> @(β ==> a ==> b ==> (a, b)))
def tst3b : {α : Type} → {β : Type} → α → β → α × β :=
{α} ==> {β} ==> a ==> b ==> (a, b)
syntax "function" (term:max)+ "=>" term : term
macro_rules
| `(function $xs* => $b) => `(@(fun $xs* => $b))
def tst4 : {α : Type} → {β : Type} → α → β → α × β :=
function α β a b => (a, b)
theorem simple20 (x y z : Nat) : y = z → x = x → x = y → x = z :=
by intros h1 h2 h3;
try clear x; -- should fail
clear h2;
traceState;
apply Eq.trans;
exact h3;
exact h1
theorem simple21 (x y z : Nat) : y = z → x = x → y = x → x = z :=
fun h1 _ h3 =>
have x = y from by { apply Eq.symm; assumption };
Eq.trans this (by assumption)
theorem simple22 (x y z : Nat) : y = z → y = x → id (x = z + 0) :=
fun h1 h2 => show x = z + 0 by
apply Eq.trans
exact h2.symm
assumption
skip
theorem simple23 (x y z : Nat) : y = z → x = x → y = x → x = z :=
fun h1 _ h3 =>
have x = y by apply Eq.symm; assumption
Eq.trans this (by assumption)
theorem simple24 (x y z : Nat) : y = z → x = x → y = x → x = z :=
fun h1 _ h3 =>
have h : x = y by apply Eq.symm; assumption
Eq.trans h (by assumption)
def f1 (x : Nat) : Nat :=
let double x := x + x
let rec loop x :=
match x with
| 0 => 0
| x+1 => loop x + double x
loop x
#eval f1 5
def f2 (x : Nat) : String :=
let bad x : String := toString x
bad x
def f3 x y :=
x + y + 1
theorem f3eq x y : f3 x y = x + y + 1 :=
rfl
def f4 (x y : Nat) : String :=
if x > y + 1 then "hello" else "world"
|
817690ad0843585ce39e5c7ba37966e0881fdcc5 | 38aa1f7792ba7c73b43619c5d089e15d69cd32eb | /sokoban.lean | 2bfdc27620d97c341b2ba9184f2fd3bb604fbc5b | [] | no_license | mirefek/my-lean-experiments | f8ec3efa4013285b80cd45c219a7bc8b6294b8cc | 1218fecbf568669ac123256d430a151a900f67b3 | refs/heads/master | 1,679,449,694,211 | 1,616,190,468,000 | 1,616,190,468,000 | 154,370,734 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 7,475 | lean | import tactic
import data.list.func
universe u
def list2d (α : Type u) := list (list α)
namespace list2d
open list.func
variables {α : Type} {β : Type}
variables [inhabited α] [inhabited β]
@[simp] def get2d (xy : ℕ × ℕ) (l : list2d α) : α
:= let (x,y) := xy in get x (get y l)
@[simp] def set2d (a : α) (l : list2d α) (xy : ℕ × ℕ) : list2d α
:= let (x,y) := xy in set (set a (get y l) x) l y
@[simp] def dfzip2d (l1 : list2d α) (l2 : list2d β) : list2d (α × β)
:= (pointwise (pointwise prod.mk) l1 l2)
@[simp] def add_to_line1 (a : α) : list2d α -> list2d α
| [] := [[a]]
| (h::t) := (a::h)::t
@[simp] def transpose : list2d α → list2d α := (list.foldr (pointwise list.cons)) []
instance [has_repr α] : has_repr (list2d α) := ⟨λ l, list.repr (l : list (list α))⟩
#eval transpose [[1, 2], [3, 4, 5], [6]]
end list2d
inductive direction : Type
| up
| down
| left
| right
namespace direction
def opposite : direction -> direction
| up := down
| down := up
| left := right
| right := left
def shift : direction -> (ℕ × ℕ) -> option (ℕ × ℕ)
| up (_, 0) := none
| up (x, y+1) := some (x, y)
| down (x, y) := some (x, y+1)
| left (0, _) := none
| left (x+1, y) := some (x, y)
| right (x, y) := some (x+1, y)
end direction
structure sokoban :=
(available : list2d bool)
(boxes : list2d bool)
(storages : list2d bool)
(storekeeper : ℕ × ℕ)
namespace sokoban
open list2d
instance : inhabited sokoban
:= ⟨{ available := [[tt]], boxes := [], storages := [], storekeeper := (0,0) }⟩
def move (d : direction) (s : sokoban) : sokoban :=
match (d.shift s.storekeeper) with none := s
| some sk2 :=
if get2d sk2 s.available = false then s else
if get2d sk2 s.boxes = false then
{ storekeeper := sk2, ..s}
else
match (d.shift sk2) with none := s
| some box2 :=
if (get2d box2 s.available = false)
∨ (get2d box2 s.boxes = true) then s else
{
boxes := (s.boxes.set2d ff sk2).set2d tt box2,
storekeeper := sk2, ..s
}
end
end
def move_up := move direction.up
def move_down := move direction.down
def move_left := move direction.left
def move_right := move direction.right
def add_newline (s : sokoban) : sokoban := {
available := []::s.available,
boxes := []::s.boxes,
storages := []::s.storages,
storekeeper := match s.storekeeper with (x,y) := (x,y+1) end
}
def add_newsquare (av box stor sk : bool) (s : sokoban) : sokoban := {
available := add_to_line1 av s.available,
boxes := add_to_line1 box s.boxes,
storages := add_to_line1 stor s.storages,
storekeeper := if sk then (0, 0) else match s.storekeeper with
| (x,0) := (x+1,0)
| xy := xy
end
}
def from_string_aux : list char → option (sokoban × bool)
| [] := some (sokoban.mk [] [] [] (0,0), ff)
| (c::str) := match (from_string_aux str), c with
| none, _ := none
| (some (s, sk_set)), '\n' := some (add_newline s, sk_set)
| (some (s, sk_set)), ' ' := some (add_newsquare tt ff ff ff s, sk_set)
| (some (s, sk_set)), '#' := some (add_newsquare ff ff ff ff s, sk_set)
| (some (s, sk_set)), '.' := some (add_newsquare tt ff tt ff s, sk_set)
| (some (s, sk_set)), '$' := some (add_newsquare tt tt ff ff s, sk_set)
| (some (s, sk_set)), '*' := some (add_newsquare tt tt tt ff s, sk_set)
| (some (s, ff)), '@' := some (add_newsquare tt ff ff tt s, tt)
| (some (s, ff)), '+' := some (add_newsquare tt ff tt tt s, tt)
| (some _), _ := none
end
def from_string (str : string) : sokoban :=
match (from_string_aux str.to_list) with
| none := default sokoban
| some (_, ff) := default sokoban
| some (level, tt) := level
end
def square_to_char : bool → bool → bool → bool → char
| tt ff ff ff := ' '
| ff ff ff ff := '#'
| tt ff tt ff := '.'
| tt tt ff ff := '$'
| tt tt tt ff := '*'
| tt ff ff tt := '@'
| tt ff tt tt := '+'
| _ _ _ _ := '?'
def to_string_aux1 (str : list char) : list (bool × bool × bool × bool) → list char
| [] := str
| ((av,box,stor,sk)::t) := (square_to_char av box stor sk)::(to_string_aux1 t)
def to_string_aux2 : list2d (bool × bool × bool × bool) → list char
| [] := []
| (h::t) := to_string_aux1 ('\n'::(to_string_aux2 t)) h
instance : has_to_string sokoban := ⟨λ s,
list.as_string (to_string_aux2
(dfzip2d s.available (dfzip2d s.boxes (dfzip2d s.storages (set2d true [] s.storekeeper)))))
⟩
instance : has_repr sokoban
:= ⟨λ s, (string.append (string.append "sokoban.from_string \"" (to_string s)) "\"")⟩
inductive solvable : sokoban -> Prop
| solved (s : sokoban) (H : s.boxes = s.storages) : solvable s
| move (d : direction) (s : sokoban) (H : solvable (s.move d)) : solvable s
def solvable.move_up := solvable.move direction.up
def solvable.move_down := solvable.move direction.down
def solvable.move_left := solvable.move direction.left
def solvable.move_right := solvable.move direction.right
meta def soko_simp_root (e : expr) : tactic unit :=
do
soko ← tactic.eval_expr sokoban e,
tactic.trace (to_string soko),
let p : pexpr := ``(%%e = sokoban.mk
%%soko.available %%soko.boxes %%soko.storages %%soko.storekeeper),
eq ← tactic.to_expr p,
name ← tactic.get_unused_name,
H ← tactic.assert name eq,
tactic.reflexivity,
tactic.rewrite_target H,
tactic.clear H
meta def soko_simp_expr : expr → tactic unit := assume e : expr,
soko_simp_root e <|> match e with
| expr.app e1 e2 := soko_simp_expr e1 >> soko_simp_expr e2
| _ := return ()
end
meta def soko_simp : tactic unit :=
do
goal ← tactic.target,
soko_simp_expr goal
#check tactic.apply
meta def solve_up : tactic unit := tactic.apply `(solvable.move_up) >> soko_simp
meta def solve_down : tactic unit := tactic.apply `(solvable.move_down) >> soko_simp
meta def solve_left : tactic unit := tactic.apply `(solvable.move_left) >> soko_simp
meta def solve_right : tactic unit := tactic.apply `(solvable.move_right) >> soko_simp
meta def solve_finish : tactic unit := tactic.apply `(sokoban.solvable.solved) >> tactic.reflexivity
end sokoban
def soko_level := sokoban.from_string "
#######
#. . .#
# $$$ #
#.$@$.#
# $$$ #
#. . .#
#######
"
example : soko_level.solvable :=
begin
sokoban.soko_simp,
sokoban.solve_up,
sokoban.solve_left,
sokoban.solve_right,
sokoban.solve_right,
sokoban.solve_left,
sokoban.solve_down,
sokoban.solve_down,
sokoban.solve_left,
sokoban.solve_right,
sokoban.solve_right,
sokoban.solve_up,
sokoban.solve_right,
sokoban.solve_up,
sokoban.solve_down,
sokoban.solve_left,
sokoban.solve_left,
sokoban.solve_up,
sokoban.solve_left,
sokoban.solve_down,
sokoban.solve_left,
sokoban.solve_down,
sokoban.solve_right,
sokoban.solve_up,
sokoban.solve_up,
sokoban.solve_up,
sokoban.solve_left,
sokoban.solve_down,
sokoban.solve_right,
sokoban.solve_down,
sokoban.solve_right,
sokoban.solve_right,
sokoban.solve_right,
sokoban.solve_up,
sokoban.solve_left,
sokoban.solve_down,
sokoban.solve_down,
sokoban.solve_down,
sokoban.solve_right,
sokoban.solve_up,
sokoban.solve_left,
sokoban.solve_up,
sokoban.solve_up,
sokoban.solve_up,
sokoban.solve_left,
sokoban.solve_left,
sokoban.solve_down,
sokoban.solve_down,
sokoban.solve_down,
sokoban.solve_down,
sokoban.solve_right,
sokoban.solve_right,
sokoban.solve_up,
sokoban.solve_up,
sokoban.solve_left,
sokoban.solve_down,
sokoban.solve_up,
sokoban.solve_up,
sokoban.solve_finish
end
|
ee37c3ef14d16567bbf344d0e47a7eb89c93bd23 | 4727251e0cd73359b15b664c3170e5d754078599 | /archive/imo/imo2011_q5.lean | 92d259f5d184f6175964d53c5c993a77c6d821fc | [
"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 | 2,094 | lean | /-
Copyright (c) 2021 Alain Verberkmoes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Alain Verberkmoes
-/
import data.int.basic
/-!
# IMO 2011 Q5
Let `f` be a function from the set of integers to the set
of positive integers. Suppose that, for any two integers
`m` and `n`, the difference `f(m) - f(n)` is divisible by
`f(m - n)`. Prove that, for all integers `m` and `n` with
`f(m) ≤ f(n)`, the number `f(n)` is divisible by `f(m)`.
-/
open int
theorem imo2011_q5 (f : ℤ → ℤ) (hpos : ∀ n : ℤ, 0 < f n)
(hdvd : ∀ m n : ℤ, f (m - n) ∣ f m - f n) :
∀ m n : ℤ, f m ≤ f n → f m ∣ f n :=
begin
intros m n h_fm_le_fn,
cases lt_or_eq_of_le h_fm_le_fn with h_fm_lt_fn h_fm_eq_fn,
{ -- m < n
let d := f m - f (m - n),
have h_fn_dvd_d : f n ∣ d,
{ rw ←sub_sub_self m n,
exact hdvd m (m - n) },
have h_d_lt_fn : d < f n,
{ calc d < f m : sub_lt_self _ (hpos (m - n))
... < f n : h_fm_lt_fn },
have h_neg_d_lt_fn : -d < f n,
{ calc -d = f (m - n) - f m : neg_sub _ _
... < f (m - n) : sub_lt_self _ (hpos m)
... ≤ f n - f m : le_of_dvd (sub_pos.mpr h_fm_lt_fn) _
... < f n : sub_lt_self _ (hpos m),
-- ⊢ f (m - n) ∣ f n - f m
rw [←dvd_neg, neg_sub], exact hdvd m n },
have h_d_eq_zero : d = 0,
{ obtain (hd | hd | hd) : d > 0 ∨ d = 0 ∨ d < 0 := trichotomous d 0,
{ -- d > 0
have h₁ : f n ≤ d, from le_of_dvd hd h_fn_dvd_d,
have h₂ : ¬ f n ≤ d, from not_le.mpr h_d_lt_fn,
contradiction },
{ -- d = 0
exact hd },
{ -- d < 0
have h₁ : f n ≤ -d, from le_of_dvd (neg_pos.mpr hd) ((dvd_neg _ _).mpr h_fn_dvd_d),
have h₂ : ¬ f n ≤ -d, from not_le.mpr h_neg_d_lt_fn,
contradiction } },
have h₁ : f m = f (m - n), from sub_eq_zero.mp h_d_eq_zero,
have h₂ : f (m - n) ∣ f m - f n, from hdvd m n,
rw ←h₁ at h₂,
exact (dvd_iff_dvd_of_dvd_sub h₂).mp dvd_rfl },
{ -- m = n
rw h_fm_eq_fn }
end
|
cc6ce7a8a77f66e2e5b05ddf785cb47983fbfa09 | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/tactic/simpa.lean | 82f1d6140474bf7841d1c6adfbf9747fcc1b3699 | [
"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 | 2,399 | 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 tactic.doc_commands
namespace tactic
namespace interactive
open interactive interactive.types expr lean.parser
local postfix `?`:9001 := optional
/--
This is a "finishing" tactic modification of `simp`. It has two forms.
* `simpa [rules, ...] using e` will simplify the goal and the type of
`e` using `rules`, then try to close the goal using `e`.
Simplifying the type of `e` makes it more likely to match the goal
(which has also been simplified). This construction also tends to be
more robust under changes to the simp lemma set.
* `simpa [rules, ...]` will simplify the goal and the type of a
hypothesis `this` if present in the context, then try to close the goal using
the `assumption` tactic. -/
meta def simpa (use_iota_eqn : parse $ (tk "!")?) (trace_lemmas : parse $ (tk "?")?)
(no_dflt : parse only_flag) (hs : parse simp_arg_list) (attr_names : parse with_ident_list)
(tgt : parse (tk "using" *> texpr)?) (cfg : simp_config_ext := {}) : tactic unit :=
let simp_at lc (close_tac : tactic unit) := focus1 $
simp use_iota_eqn trace_lemmas no_dflt hs attr_names (loc.ns lc)
{fail_if_unchanged := ff, ..cfg} >>
(((close_tac <|> trivial) >> done) <|> fail "simpa failed") in
match tgt with
| none := get_local `this >> simp_at [some `this, none] assumption <|> simp_at [none] assumption
| some e := focus1 $ do
e ← i_to_expr e <|> do {
ty ← target,
-- for positional error messages, we don't care about the result
e ← i_to_expr_strict ``(%%e : %%ty),
pty ← pp ty, ptgt ← pp e,
-- Fail deliberately, to advise regarding `simp; exact` usage
fail ("simpa failed, 'using' expression type not directly " ++
"inferrable. Try:\n\nsimpa ... using\nshow " ++
to_fmt pty ++ ",\nfrom " ++ ptgt : format) },
match e with
| local_const _ lc _ _ := simp_at [some lc, none] (get_local lc >>= tactic.exact)
| e := do
t ← infer_type e,
assertv `this t e,
simp_at [some `this, none] (get_local `this >>= tactic.exact),
all_goals (try apply_instance)
end
end
add_tactic_doc
{ name := "simpa",
category := doc_category.tactic,
decl_names := [`tactic.interactive.simpa],
tags := ["simplification"] }
end interactive
end tactic
|
3930c1f9a4e887f062af211e101d88808329962f | 618003631150032a5676f229d13a079ac875ff77 | /src/category_theory/monad/basic.lean | 0f5c9b32929b36b14a99829eaca8c519989d2943 | [
"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 | 2,109 | lean | /-
Copyright (c) 2019 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.functor_category
namespace category_theory
open category
universes v₁ u₁ -- declare the `v`'s first; see `category_theory.category` for an explanation
variables {C : Type u₁} [category.{v₁} C]
/--
The data of a monad on C consists of an endofunctor T together with natural transformations
η : 𝟭 C ⟶ T and μ : T ⋙ T ⟶ T satisfying three equations:
- T μ_X ≫ μ_X = μ_(TX) ≫ μ_X (associativity)
- η_(TX) ≫ μ_X = 1_X (left unit)
- Tη_X ≫ μ_X = 1_X (right unit)
-/
class monad (T : C ⥤ C) :=
(η [] : 𝟭 _ ⟶ T)
(μ [] : T ⋙ T ⟶ T)
(assoc' : ∀ X : C, T.map (nat_trans.app μ X) ≫ μ.app _ = μ.app (T.obj X) ≫ μ.app _ . obviously)
(left_unit' : ∀ X : C, η.app (T.obj X) ≫ μ.app _ = 𝟙 _ . obviously)
(right_unit' : ∀ X : C, T.map (η.app X) ≫ μ.app _ = 𝟙 _ . obviously)
restate_axiom monad.assoc'
restate_axiom monad.left_unit'
restate_axiom monad.right_unit'
attribute [simp] monad.left_unit monad.right_unit
notation `η_` := monad.η
notation `μ_` := monad.μ
/--
The data of a comonad on C consists of an endofunctor G together with natural transformations
ε : G ⟶ 𝟭 C and δ : G ⟶ G ⋙ G satisfying three equations:
- δ_X ≫ G δ_X = δ_X ≫ δ_(GX) (coassociativity)
- δ_X ≫ ε_(GX) = 1_X (left counit)
- δ_X ≫ G ε_X = 1_X (right counit)
-/
class comonad (G : C ⥤ C) :=
(ε [] : G ⟶ 𝟭 _)
(δ [] : G ⟶ (G ⋙ G))
(coassoc' : ∀ X : C, nat_trans.app δ _ ≫ G.map (δ.app X) = δ.app _ ≫ δ.app _ . obviously)
(left_counit' : ∀ X : C, δ.app X ≫ ε.app (G.obj X) = 𝟙 _ . obviously)
(right_counit' : ∀ X : C, δ.app X ≫ G.map (ε.app X) = 𝟙 _ . obviously)
restate_axiom comonad.coassoc'
restate_axiom comonad.left_counit'
restate_axiom comonad.right_counit'
attribute [simp] comonad.left_counit comonad.right_counit
notation `ε_` := comonad.ε
notation `δ_` := comonad.δ
end category_theory
|
58cf7242f50fe7ce31555441a18f5e865fe9a9c8 | 7b89826c26634aa18c0110f1634f73027851edfe | /natural-number-game/src/main.lean | c0fd1a4770afe71fc9f4b2247e1e88964cb799d4 | [
"MIT"
] | permissive | marcofavorito/leanings | b7642344d8c9012a1cec74a804c5884297880c4d | 581b83be66ff4f8dd946fb6a1bb045d2ddf91076 | refs/heads/master | 1,672,310,991,244 | 1,603,031,766,000 | 1,603,031,766,000 | 279,163,004 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 307 | lean | import mynat.definition -- imports the natural numbers {0,1,2,3,4,...}.
import mynat.add -- imports definition of addition on the natural numbers.
import mynat.mul -- imports definition of multiplication on the natural numbers.
lemma example1 (x y z : mynat) : x * y + z = x * y + z :=
begin
refl,
end
|
0470436539416339c5384bc4f839aca8def7cf2a | e898bfefd5cb60a60220830c5eba68cab8d02c79 | /uexp/src/uexp/rules/transitiveInferenceJoin.lean | 83cb35f5b393e7c63241552aeb3dbe4754ff2520 | [
"BSD-2-Clause"
] | permissive | kkpapa/Cosette | 9ed09e2dc4c1ecdef815c30b5501f64a7383a2ce | fda8fdbbf0de6c1be9b4104b87bbb06cede46329 | refs/heads/master | 1,584,573,128,049 | 1,526,370,422,000 | 1,526,370,422,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 2,261 | lean | import ..sql
import ..tactics
import ..u_semiring
import ..extra_constants
import ..ucongr
import ..TDP
set_option profiler true
open Expr
open Proj
open Pred
open SQL
open tree
notation `int` := datatypes.int
variable integer_1: const datatypes.int
variable integer_7: const datatypes.int
theorem rule:
forall ( Γ scm_t scm_account scm_bonus scm_dept scm_emp: Schema) (rel_t: relation scm_t) (rel_account: relation scm_account) (rel_bonus: relation scm_bonus) (rel_dept: relation scm_dept) (rel_emp: relation scm_emp) (t_k0 : Column int scm_t) (t_c1 : Column int scm_t) (t_f1_a0 : Column int scm_t) (t_f2_a0 : Column int scm_t) (t_f0_c0 : Column int scm_t) (t_f1_c0 : Column int scm_t) (t_f0_c1 : Column int scm_t) (t_f1_c2 : Column int scm_t) (t_f2_c3 : Column int scm_t) (account_acctno : Column int scm_account) (account_type : Column int scm_account) (account_balance : Column int scm_account) (bonus_ename : Column int scm_bonus) (bonus_job : Column int scm_bonus) (bonus_sal : Column int scm_bonus) (bonus_comm : Column int scm_bonus) (dept_deptno : Column int scm_dept) (dept_name : Column int scm_dept) (emp_empno : Column int scm_emp) (emp_ename : Column int scm_emp) (emp_job : Column int scm_emp) (emp_mgr : Column int scm_emp) (emp_hiredate : Column int scm_emp) (emp_comm : Column int scm_emp) (emp_sal : Column int scm_emp) (emp_deptno : Column int scm_emp) (emp_slacker : Column int scm_emp),
denoteSQL ((SELECT1 (e2p (constantExpr integer_1)) FROM1 (product (table rel_emp) ((SELECT * FROM1 (table rel_emp) WHERE (castPred (combine (right⋅emp_deptno) (e2p (constantExpr integer_7)) ) predicates.gt)))) WHERE (equal (uvariable (right⋅left⋅emp_deptno)) (uvariable (right⋅right⋅emp_deptno)))) :SQL Γ _)
=
denoteSQL ((SELECT1 (e2p (constantExpr integer_1)) FROM1 (product ((SELECT * FROM1 (table rel_emp) WHERE (castPred (combine (right⋅emp_deptno) (e2p (constantExpr integer_7)) ) predicates.gt))) ((SELECT * FROM1 (table rel_emp) WHERE (castPred (combine (right⋅emp_deptno) (e2p (constantExpr integer_7)) ) predicates.gt)))) WHERE (equal (uvariable (right⋅left⋅emp_deptno)) (uvariable (right⋅right⋅emp_deptno)))) :SQL Γ _) :=
begin
intros,
unfold_all_denotations,
funext,
try {simp},
print_size,
TDP
end |
dddb403a2e901a7744fe32f67331d21b68906fdd | 0c1546a496eccfb56620165cad015f88d56190c5 | /library/data/set/basic.lean | 4fab1bbcfed9ff6ea1bafd47dda401cfc3ea78b2 | [
"Apache-2.0"
] | permissive | Solertis/lean | 491e0939957486f664498fbfb02546e042699958 | 84188c5aa1673fdf37a082b2de8562dddf53df3f | refs/heads/master | 1,610,174,257,606 | 1,486,263,620,000 | 1,486,263,620,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 2,715 | lean | /-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Jeremy Avigad, Leonardo de Moura
-/
namespace set
universe variable u
variable {α : Type u}
lemma ext {a b : set α} (h : ∀ x, x ∈ a ↔ x ∈ b) : a = b :=
funext (take x, propext (h x))
lemma subset.refl (a : set α) : a ⊆ a := take x, assume H, H
lemma subset.trans {a b c : set α} (subab : a ⊆ b) (subbc : b ⊆ c) : a ⊆ c :=
take x, assume ax, subbc (subab ax)
lemma subset.antisymm {a b : set α} (h₁ : a ⊆ b) (h₂ : b ⊆ a) : a = b :=
ext (λ x, iff.intro (λ ina, h₁ ina) (λ inb, h₂ inb))
-- an alterantive name
lemma eq_of_subset_of_subset {a b : set α} (h₁ : a ⊆ b) (h₂ : b ⊆ a) : a = b :=
subset.antisymm h₁ h₂
lemma mem_of_subset_of_mem {s₁ s₂ : set α} {a : α} : s₁ ⊆ s₂ → a ∈ s₁ → a ∈ s₂ :=
assume h₁ h₂, h₁ h₂
lemma not_mem_empty (x : α) : ¬ (x ∈ (∅ : set α)) :=
assume h : x ∈ ∅, h
lemma mem_empty_eq (x : α) : x ∈ (∅ : set α) = false :=
rfl
lemma eq_empty_of_forall_not_mem {s : set α} (h : ∀ x, x ∉ s) : s = ∅ :=
ext (take x, iff.intro
(assume xs, absurd xs (h x))
(assume xe, absurd xe (not_mem_empty _)))
lemma ne_empty_of_mem {s : set α} {x : α} (h : x ∈ s) : s ≠ ∅ :=
begin intro hs, rewrite hs at h, apply not_mem_empty _ h end
lemma empty_subset (s : set α) : ∅ ⊆ s :=
take x, assume h, false.elim h
lemma eq_empty_of_subset_empty {s : set α} (h : s ⊆ ∅) : s = ∅ :=
subset.antisymm h (empty_subset s)
lemma union_comm (a b : set α) : a ∪ b = b ∪ a :=
ext (take x, or.comm)
lemma union_assoc (a b c : set α) : (a ∪ b) ∪ c = a ∪ (b ∪ c) :=
ext (take x, or.assoc)
instance union_is_assoc : is_associative (set α) union :=
⟨union_assoc⟩
instance union_is_comm : is_commutative (set α) union :=
⟨union_comm⟩
lemma union_self (a : set α) : a ∪ a = a :=
ext (take x, or_self _)
lemma union_empty (a : set α) : a ∪ ∅ = a :=
ext (take x, or_false _)
lemma empty_union (a : set α) : ∅ ∪ a = a :=
ext (take x, false_or _)
lemma inter_comm (a b : set α) : a ∩ b = b ∩ a :=
ext (take x, and.comm)
lemma inter_assoc (a b c : set α) : (a ∩ b) ∩ c = a ∩ (b ∩ c) :=
ext (take x, and.assoc)
instance inter_is_assoc : is_associative (set α) inter :=
⟨inter_assoc⟩
instance inter_is_comm : is_commutative (set α) union :=
⟨union_comm⟩
lemma inter_self (a : set α) : a ∩ a = a :=
ext (take x, and_self _)
lemma inter_empty (a : set α) : a ∩ ∅ = ∅ :=
ext (take x, and_false _)
lemma empty_inter (a : set α) : ∅ ∩ a = ∅ :=
ext (take x, false_and _)
end set
|
7ccd78c705f5938ddadd881b9a59796fd2d5b5da | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/number_theory/fermat4.lean | b9fc62467ee9d025d38b7215dde8e50efada1559 | [
"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 | 11,786 | lean | /-
Copyright (c) 2020 Paul van Wamelen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Paul van Wamelen
-/
import number_theory.pythagorean_triples
import ring_theory.coprime.lemmas
import tactic.linear_combination
/-!
# Fermat's Last Theorem for the case n = 4
There are no non-zero integers `a`, `b` and `c` such that `a ^ 4 + b ^ 4 = c ^ 4`.
-/
noncomputable theory
open_locale classical
/-- Shorthand for three non-zero integers `a`, `b`, and `c` satisfying `a ^ 4 + b ^ 4 = c ^ 2`.
We will show that no integers satisfy this equation. Clearly Fermat's Last theorem for n = 4
follows. -/
def fermat_42 (a b c : ℤ) : Prop := a ≠ 0 ∧ b ≠ 0 ∧ a ^ 4 + b ^ 4 = c ^ 2
namespace fermat_42
lemma comm {a b c : ℤ} :
(fermat_42 a b c) ↔ (fermat_42 b a c) :=
by { delta fermat_42, rw add_comm, tauto }
lemma mul {a b c k : ℤ} (hk0 : k ≠ 0) :
fermat_42 a b c ↔ fermat_42 (k * a) (k * b) (k ^ 2 * c) :=
begin
delta fermat_42,
split,
{ intro f42,
split, { exact mul_ne_zero hk0 f42.1 },
split, { exact mul_ne_zero hk0 f42.2.1 },
{ have H : a ^ 4 + b ^ 4 = c ^ 2 := f42.2.2,
linear_combination k ^ 4 * H } },
{ intro f42,
split, { exact right_ne_zero_of_mul f42.1 },
split, { exact right_ne_zero_of_mul f42.2.1 },
apply (mul_right_inj' (pow_ne_zero 4 hk0)).mp,
linear_combination f42.2.2 }
end
lemma ne_zero {a b c : ℤ} (h : fermat_42 a b c) : c ≠ 0 :=
begin
apply ne_zero_pow two_ne_zero _, apply ne_of_gt,
rw [← h.2.2, (by ring : a ^ 4 + b ^ 4 = (a ^ 2) ^ 2 + (b ^ 2) ^ 2)],
exact add_pos (sq_pos_of_ne_zero _ (pow_ne_zero 2 h.1))
(sq_pos_of_ne_zero _ (pow_ne_zero 2 h.2.1))
end
/-- We say a solution to `a ^ 4 + b ^ 4 = c ^ 2` is minimal if there is no other solution with
a smaller `c` (in absolute value). -/
def minimal (a b c : ℤ) : Prop :=
(fermat_42 a b c) ∧ ∀ (a1 b1 c1 : ℤ), (fermat_42 a1 b1 c1) → int.nat_abs c ≤ int.nat_abs c1
/-- if we have a solution to `a ^ 4 + b ^ 4 = c ^ 2` then there must be a minimal one. -/
lemma exists_minimal {a b c : ℤ} (h : fermat_42 a b c) :
∃ (a0 b0 c0), (minimal a0 b0 c0) :=
begin
let S : set ℕ := { n | ∃ (s : ℤ × ℤ × ℤ), fermat_42 s.1 s.2.1 s.2.2 ∧ n = int.nat_abs s.2.2},
have S_nonempty : S.nonempty,
{ use int.nat_abs c,
rw set.mem_set_of_eq,
use ⟨a, ⟨b, c⟩⟩, tauto },
let m : ℕ := nat.find S_nonempty,
have m_mem : m ∈ S := nat.find_spec S_nonempty,
rcases m_mem with ⟨s0, hs0, hs1⟩,
use [s0.1, s0.2.1, s0.2.2, hs0],
intros a1 b1 c1 h1,
rw ← hs1,
apply nat.find_min',
use ⟨a1, ⟨b1, c1⟩⟩, tauto
end
/-- a minimal solution to `a ^ 4 + b ^ 4 = c ^ 2` must have `a` and `b` coprime. -/
lemma coprime_of_minimal {a b c : ℤ} (h : minimal a b c) : is_coprime a b :=
begin
apply int.gcd_eq_one_iff_coprime.mp,
by_contradiction hab,
obtain ⟨p, hp, hpa, hpb⟩ := nat.prime.not_coprime_iff_dvd.mp hab,
obtain ⟨a1, rfl⟩ := (int.coe_nat_dvd_left.mpr hpa),
obtain ⟨b1, rfl⟩ := (int.coe_nat_dvd_left.mpr hpb),
have hpc : (p : ℤ) ^ 2 ∣ c,
{ rw [←int.pow_dvd_pow_iff zero_lt_two, ←h.1.2.2],
apply dvd.intro (a1 ^ 4 + b1 ^ 4), ring },
obtain ⟨c1, rfl⟩ := hpc,
have hf : fermat_42 a1 b1 c1,
exact (fermat_42.mul (int.coe_nat_ne_zero.mpr (nat.prime.ne_zero hp))).mpr h.1,
apply nat.le_lt_antisymm (h.2 _ _ _ hf),
rw [int.nat_abs_mul, lt_mul_iff_one_lt_left, int.nat_abs_pow, int.nat_abs_of_nat],
{ exact nat.one_lt_pow _ _ zero_lt_two (nat.prime.one_lt hp) },
{ exact (nat.pos_of_ne_zero (int.nat_abs_ne_zero_of_ne_zero (ne_zero hf))) },
end
/-- We can swap `a` and `b` in a minimal solution to `a ^ 4 + b ^ 4 = c ^ 2`. -/
lemma minimal_comm {a b c : ℤ} : (minimal a b c) → (minimal b a c) :=
λ ⟨h1, h2⟩, ⟨fermat_42.comm.mp h1, h2⟩
/-- We can assume that a minimal solution to `a ^ 4 + b ^ 4 = c ^ 2` has positive `c`. -/
lemma neg_of_minimal {a b c : ℤ} :
(minimal a b c) → (minimal a b (-c)) :=
begin
rintros ⟨⟨ha, hb, heq⟩, h2⟩,
split,
{ apply and.intro ha (and.intro hb _),
rw heq, exact (neg_sq c).symm },
rwa (int.nat_abs_neg c),
end
/-- We can assume that a minimal solution to `a ^ 4 + b ^ 4 = c ^ 2` has `a` odd. -/
lemma exists_odd_minimal {a b c : ℤ} (h : fermat_42 a b c) :
∃ (a0 b0 c0), (minimal a0 b0 c0) ∧ a0 % 2 = 1 :=
begin
obtain ⟨a0, b0, c0, hf⟩ := exists_minimal h,
cases int.mod_two_eq_zero_or_one a0 with hap hap,
{ cases int.mod_two_eq_zero_or_one b0 with hbp hbp,
{ exfalso,
have h1 : 2 ∣ (int.gcd a0 b0 : ℤ),
{ exact int.dvd_gcd (int.dvd_of_mod_eq_zero hap) (int.dvd_of_mod_eq_zero hbp) },
rw int.gcd_eq_one_iff_coprime.mpr (coprime_of_minimal hf) at h1, revert h1, norm_num },
{ exact ⟨b0, ⟨a0, ⟨c0, minimal_comm hf, hbp⟩⟩⟩ } },
exact ⟨a0, ⟨b0, ⟨c0 , hf, hap⟩⟩⟩,
end
/-- We can assume that a minimal solution to `a ^ 4 + b ^ 4 = c ^ 2` has
`a` odd and `c` positive. -/
lemma exists_pos_odd_minimal {a b c : ℤ} (h : fermat_42 a b c) :
∃ (a0 b0 c0), (minimal a0 b0 c0) ∧ a0 % 2 = 1 ∧ 0 < c0 :=
begin
obtain ⟨a0, b0, c0, hf, hc⟩ := exists_odd_minimal h,
rcases lt_trichotomy 0 c0 with (h1 | rfl | h1),
{ use [a0, b0, c0], tauto },
{ exfalso, exact ne_zero hf.1 rfl},
{ use [a0, b0, -c0, neg_of_minimal hf, hc],
exact neg_pos.mpr h1 },
end
end fermat_42
lemma int.coprime_of_sq_sum {r s : ℤ} (h2 : is_coprime s r) :
is_coprime (r ^ 2 + s ^ 2) r :=
begin
rw [sq, sq],
exact (is_coprime.mul_left h2 h2).mul_add_left_left r
end
lemma int.coprime_of_sq_sum' {r s : ℤ} (h : is_coprime r s) :
is_coprime (r ^ 2 + s ^ 2) (r * s) :=
begin
apply is_coprime.mul_right (int.coprime_of_sq_sum (is_coprime_comm.mp h)),
rw add_comm, apply int.coprime_of_sq_sum h
end
namespace fermat_42
-- If we have a solution to a ^ 4 + b ^ 4 = c ^ 2, we can construct a smaller one. This
-- implies there can't be a smallest solution.
lemma not_minimal {a b c : ℤ}
(h : minimal a b c) (ha2 : a % 2 = 1) (hc : 0 < c) : false :=
begin
-- Use the fact that a ^ 2, b ^ 2, c form a pythagorean triple to obtain m and n such that
-- a ^ 2 = m ^ 2 - n ^ 2, b ^ 2 = 2 * m * n and c = m ^ 2 + n ^ 2
-- first the formula:
have ht : pythagorean_triple (a ^ 2) (b ^ 2) c,
{ delta pythagorean_triple,
linear_combination h.1.2.2 },
-- coprime requirement:
have h2 : int.gcd (a ^ 2) (b ^ 2) = 1 :=
int.gcd_eq_one_iff_coprime.mpr (coprime_of_minimal h).pow,
-- in order to reduce the possibilities we get from the classification of pythagorean triples
-- it helps if we know the parity of a ^ 2 (and the sign of c):
have ha22 : a ^ 2 % 2 = 1, { rw [sq, int.mul_mod, ha2], norm_num },
obtain ⟨m, n, ht1, ht2, ht3, ht4, ht5, ht6⟩ := ht.coprime_classification' h2 ha22 hc,
-- Now a, n, m form a pythagorean triple and so we can obtain r and s such that
-- a = r ^ 2 - s ^ 2, n = 2 * r * s and m = r ^ 2 + s ^ 2
-- formula:
have htt : pythagorean_triple a n m,
{ delta pythagorean_triple,
linear_combination (ht1) },
-- a and n are coprime, because a ^ 2 = m ^ 2 - n ^ 2 and m and n are coprime.
have h3 : int.gcd a n = 1,
{ apply int.gcd_eq_one_iff_coprime.mpr,
apply @is_coprime.of_mul_left_left _ _ _ a,
rw [← sq, ht1, (by ring : m ^ 2 - n ^ 2 = m ^ 2 + (-n) * n)],
exact (int.gcd_eq_one_iff_coprime.mp ht4).pow_left.add_mul_right_left (-n) },
-- m is positive because b is non-zero and b ^ 2 = 2 * m * n and we already have 0 ≤ m.
have hb20 : b ^ 2 ≠ 0 := mt pow_eq_zero h.1.2.1,
have h4 : 0 < m,
{ apply lt_of_le_of_ne ht6,
rintro rfl,
revert hb20,
rw ht2, simp },
obtain ⟨r, s, htt1, htt2, htt3, htt4, htt5, htt6⟩ := htt.coprime_classification' h3 ha2 h4,
-- Now use the fact that (b / 2) ^ 2 = m * r * s, and m, r and s are pairwise coprime to obtain
-- i, j and k such that m = i ^ 2, r = j ^ 2 and s = k ^ 2.
-- m and r * s are coprime because m = r ^ 2 + s ^ 2 and r and s are coprime.
have hcp : int.gcd m (r * s) = 1,
{ rw htt3,
exact int.gcd_eq_one_iff_coprime.mpr (int.coprime_of_sq_sum'
(int.gcd_eq_one_iff_coprime.mp htt4)) },
-- b is even because b ^ 2 = 2 * m * n.
have hb2 : 2 ∣ b,
{ apply @int.prime.dvd_pow' _ 2 _ (by norm_num : nat.prime 2),
rw [ht2, mul_assoc], exact dvd_mul_right 2 (m * n) },
cases hb2 with b' hb2',
have hs : b' ^ 2 = m * (r * s),
{ apply (mul_right_inj' (by norm_num : (4 : ℤ) ≠ 0)).mp,
linear_combination (- b - 2 * b') * hb2' + ht2 + 2 * m * htt2 },
have hrsz : r * s ≠ 0, -- because b ^ 2 is not zero and (b / 2) ^ 2 = m * (r * s)
{ by_contradiction hrsz,
revert hb20, rw [ht2, htt2, mul_assoc, @mul_assoc _ _ _ r s, hrsz],
simp },
have h2b0 : b' ≠ 0,
{ apply ne_zero_pow two_ne_zero,
rw hs, apply mul_ne_zero, { exact ne_of_gt h4}, { exact hrsz } },
obtain ⟨i, hi⟩ := int.sq_of_gcd_eq_one hcp hs.symm,
-- use m is positive to exclude m = - i ^ 2
have hi' : ¬ m = - i ^ 2,
{ by_contradiction h1,
have hit : - i ^ 2 ≤ 0, apply neg_nonpos.mpr (sq_nonneg i),
rw ← h1 at hit,
apply absurd h4 (not_lt.mpr hit) },
replace hi : m = i ^ 2, { apply or.resolve_right hi hi' },
rw mul_comm at hs,
rw [int.gcd_comm] at hcp,
-- obtain d such that r * s = d ^ 2
obtain ⟨d, hd⟩ := int.sq_of_gcd_eq_one hcp hs.symm,
-- (b / 2) ^ 2 and m are positive so r * s is positive
have hd' : ¬ r * s = - d ^ 2,
{ by_contradiction h1,
rw h1 at hs,
have h2 : b' ^ 2 ≤ 0,
{ rw [hs, (by ring : - d ^ 2 * m = - (d ^ 2 * m))],
exact neg_nonpos.mpr ((zero_le_mul_right h4).mpr (sq_nonneg d)) },
have h2' : 0 ≤ b' ^ 2, { apply sq_nonneg b' },
exact absurd (lt_of_le_of_ne h2' (ne.symm (pow_ne_zero _ h2b0))) (not_lt.mpr h2) },
replace hd : r * s = d ^ 2, { apply or.resolve_right hd hd' },
-- r = +/- j ^ 2
obtain ⟨j, hj⟩ := int.sq_of_gcd_eq_one htt4 hd,
have hj0 : j ≠ 0,
{ intro h0, rw [h0, zero_pow zero_lt_two, neg_zero, or_self] at hj,
apply left_ne_zero_of_mul hrsz hj },
rw mul_comm at hd,
rw [int.gcd_comm] at htt4,
-- s = +/- k ^ 2
obtain ⟨k, hk⟩ := int.sq_of_gcd_eq_one htt4 hd,
have hk0 : k ≠ 0,
{ intro h0, rw [h0, zero_pow zero_lt_two, neg_zero, or_self] at hk,
apply right_ne_zero_of_mul hrsz hk },
have hj2 : r ^ 2 = j ^ 4, { cases hj with hjp hjp; { rw hjp, ring } },
have hk2 : s ^ 2 = k ^ 4, { cases hk with hkp hkp; { rw hkp, ring } },
-- from m = r ^ 2 + s ^ 2 we now get a new solution to a ^ 4 + b ^ 4 = c ^ 2:
have hh : i ^ 2 = j ^ 4 + k ^ 4, { rw [← hi, htt3, hj2, hk2] },
have hn : n ≠ 0, { rw ht2 at hb20, apply right_ne_zero_of_mul hb20 },
-- and it has a smaller c: from c = m ^ 2 + n ^ 2 we see that m is smaller than c, and i ^ 2 = m.
have hic : int.nat_abs i < int.nat_abs c,
{ apply int.coe_nat_lt.mp, rw ← (int.eq_nat_abs_of_zero_le (le_of_lt hc)),
apply gt_of_gt_of_ge _ (int.abs_le_self_sq i),
rw [← hi, ht3],
apply gt_of_gt_of_ge _ (int.le_self_sq m),
exact lt_add_of_pos_right (m ^ 2) (sq_pos_of_ne_zero n hn) },
have hic' : int.nat_abs c ≤ int.nat_abs i,
{ apply (h.2 j k i),
exact ⟨hj0, hk0, hh.symm⟩ },
apply absurd (not_le_of_lt hic) (not_not.mpr hic')
end
end fermat_42
lemma not_fermat_42 {a b c : ℤ} (ha : a ≠ 0) (hb : b ≠ 0) :
a ^ 4 + b ^ 4 ≠ c ^ 2 :=
begin
intro h,
obtain ⟨a0, b0, c0, ⟨hf, h2, hp⟩⟩ :=
fermat_42.exists_pos_odd_minimal (and.intro ha (and.intro hb h)),
apply fermat_42.not_minimal hf h2 hp
end
theorem not_fermat_4 {a b c : ℤ} (ha : a ≠ 0) (hb : b ≠ 0) :
a ^ 4 + b ^ 4 ≠ c ^ 4 :=
begin
intro heq,
apply @not_fermat_42 _ _ (c ^ 2) ha hb,
rw heq, ring
end
|
4004893ed35bee0f94f9a676a9f4b8d7dd11871e | 9dd3f3912f7321eb58ee9aa8f21778ad6221f87c | /library/tools/super/selection.lean | c60f8129976381542602f8e809c576f60ac98265 | [
"Apache-2.0"
] | permissive | bre7k30/lean | de893411bcfa7b3c5572e61b9e1c52951b310aa4 | 5a924699d076dab1bd5af23a8f910b433e598d7a | refs/heads/master | 1,610,900,145,817 | 1,488,006,845,000 | 1,488,006,845,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 3,005 | lean | /-
Copyright (c) 2016 Gabriel Ebner. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Gabriel Ebner
-/
import .prover_state
namespace super
meta def simple_selection_strategy (f : (expr → expr → bool) → clause → list ℕ) : selection_strategy :=
take dc, do gt ← get_term_order, return $
if dc^.selected^.empty ∧ dc^.c^.num_lits > 0
then { dc with selected := f gt dc^.c }
else dc
meta def dumb_selection : selection_strategy :=
simple_selection_strategy $ λgt c,
match c^.lits_where clause.literal.is_neg with
| [] := list.range c^.num_lits
| neg_lit::_ := [neg_lit]
end
meta def selection21 : selection_strategy :=
simple_selection_strategy $ λgt c,
let maximal_lits := list.filter_maximal (λi j,
gt (c^.get_lit i)^.formula (c^.get_lit j)^.formula) (list.range c^.num_lits) in
if list.length maximal_lits = 1 then maximal_lits else
let neg_lits := list.filter (λi, (c^.get_lit i)^.is_neg) (list.range c^.num_lits),
maximal_neg_lits := list.filter_maximal (λi j,
gt (c^.get_lit i)^.formula (c^.get_lit j)^.formula) neg_lits in
if ¬maximal_neg_lits^.empty then
list.taken 1 maximal_neg_lits
else
maximal_lits
meta def selection22 : selection_strategy :=
simple_selection_strategy $ λgt c,
let maximal_lits := list.filter_maximal (λi j,
gt (c^.get_lit i)^.formula (c^.get_lit j)^.formula) (list.range c^.num_lits),
maximal_lits_neg := list.filter (λi, (c^.get_lit i)^.is_neg) maximal_lits in
if ¬maximal_lits_neg^.empty then
list.taken 1 maximal_lits_neg
else
maximal_lits
meta def clause_weight (c : derived_clause) : nat :=
(c^.c^.get_lits^.for (λl, expr_size l^.formula + if l^.is_pos then 10 else 1))^.sum
meta def find_minimal_by (passive : rb_map clause_id derived_clause)
{A} [has_ordering A]
(f : derived_clause → A) : clause_id :=
match rb_map.min $ rb_map.of_list $ passive^.values^.for $ λc, (f c, c^.id) with
| some id := id
| none := nat.zero
end
meta def age_of_clause_id : name → ℕ
| (name.mk_numeral i _) := unsigned.to_nat i
| _ := 0
meta def find_minimal_weight (passive : rb_map clause_id derived_clause) : clause_id :=
find_minimal_by passive $ λc, (c^.sc^.priority, clause_weight c + c^.sc^.cost, c^.sc^.age, c^.id)
meta def find_minimal_age (passive : rb_map clause_id derived_clause) : clause_id :=
find_minimal_by passive $ λc, (c^.sc^.priority, c^.sc^.age, c^.id)
meta def weight_clause_selection : clause_selection_strategy :=
take iter, do state ← state_t.read, return $ find_minimal_weight state^.passive
meta def oldest_clause_selection : clause_selection_strategy :=
take iter, do state ← state_t.read, return $ find_minimal_age state^.passive
meta def age_weight_clause_selection (thr mod : ℕ) : clause_selection_strategy :=
take iter, if iter % mod < thr then
weight_clause_selection iter
else
oldest_clause_selection iter
end super
|
fc6304e066bb3cb5bb0bc003228146c430f494d8 | d642a6b1261b2cbe691e53561ac777b924751b63 | /src/topology/metric_space/closeds.lean | 48536248e23620a8505af2cfad8af4899bd6885b | [
"Apache-2.0"
] | permissive | cipher1024/mathlib | fee56b9954e969721715e45fea8bcb95f9dc03fe | d077887141000fefa5a264e30fa57520e9f03522 | refs/heads/master | 1,651,806,490,504 | 1,573,508,694,000 | 1,573,508,694,000 | 107,216,176 | 0 | 0 | Apache-2.0 | 1,647,363,136,000 | 1,508,213,014,000 | Lean | UTF-8 | Lean | false | false | 24,033 | lean | /-
Copyright (c) 2019 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Sébastien Gouëzel
The metric and emetric space structure on the types of closed subsets and nonempty compact
subsets of a metric or emetric space
The Hausdorff distance induces an emetric space structure on the type of closed subsets
of an emetric space, called `closeds`. Its completeness, resp. compactness, resp.
second-countability, follow from the corresponding properties of the original space.
In a metric space, the type of nonempty compact subsets (called `nonempty_compacts`) also
inherits a metric space structure from the Hausdorff distance, as the Hausdorff edistance is
always finite in this context.
-/
import topology.metric_space.hausdorff_distance topology.opens
noncomputable theory
open_locale classical
universe u
open classical lattice set function topological_space filter
namespace emetric
section
variables {α : Type u} [emetric_space α] {s : set α}
/-- In emetric spaces, the Hausdorff edistance defines an emetric space structure
on the type of closed subsets -/
instance closeds.emetric_space : emetric_space (closeds α) :=
{ edist := λs t, Hausdorff_edist s.val t.val,
edist_self := λs, Hausdorff_edist_self,
edist_comm := λs t, Hausdorff_edist_comm,
edist_triangle := λs t u, Hausdorff_edist_triangle,
eq_of_edist_eq_zero :=
λs t h, subtype.eq ((Hausdorff_edist_zero_iff_eq_of_closed s.property t.property).1 h) }
/-- The edistance to a closed set depends continuously on the point and the set -/
lemma continuous_inf_edist_Hausdorff_edist :
continuous (λp : α × (closeds α), inf_edist p.1 (p.2).val) :=
begin
refine continuous_of_le_add_edist 2 (by simp) _,
rintros ⟨x, s⟩ ⟨y, t⟩,
calc inf_edist x (s.val) ≤ inf_edist x (t.val) + Hausdorff_edist (t.val) (s.val) :
inf_edist_le_inf_edist_add_Hausdorff_edist
... ≤ (inf_edist y (t.val) + edist x y) + Hausdorff_edist (t.val) (s.val) :
add_le_add_right' inf_edist_le_inf_edist_add_edist
... = inf_edist y (t.val) + (edist x y + Hausdorff_edist (s.val) (t.val)) :
by simp [add_comm, Hausdorff_edist_comm]
... ≤ inf_edist y (t.val) + (edist (x, s) (y, t) + edist (x, s) (y, t)) :
add_le_add_left' (add_le_add' (by simp [edist, le_refl]) (by simp [edist, le_refl]))
... = inf_edist y (t.val) + 2 * edist (x, s) (y, t) :
by rw [← mul_two, mul_comm]
end
/-- Subsets of a given closed subset form a closed set -/
lemma is_closed_subsets_of_is_closed (hs : is_closed s) :
is_closed {t : closeds α | t.val ⊆ s} :=
begin
refine is_closed_of_closure_subset (λt ht x hx, _),
-- t : closeds α, ht : t ∈ closure {t : closeds α | t.val ⊆ s},
-- x : α, hx : x ∈ t.val
-- goal : x ∈ s
have : x ∈ closure s,
{ refine mem_closure_iff'.2 (λε εpos, _),
rcases mem_closure_iff'.1 ht ε εpos with ⟨u, hu, Dtu⟩,
-- u : closeds α, hu : u ∈ {t : closeds α | t.val ⊆ s}, hu' : edist t u < ε
rcases exists_edist_lt_of_Hausdorff_edist_lt hx Dtu with ⟨y, hy, Dxy⟩,
-- y : α, hy : y ∈ u.val, Dxy : edist x y < ε
exact ⟨y, hu hy, Dxy⟩ },
rwa closure_eq_of_is_closed hs at this,
end
/-- By definition, the edistance on `closeds α` is given by the Hausdorff edistance -/
lemma closeds.edist_eq {s t : closeds α} : edist s t = Hausdorff_edist s.val t.val := rfl
/-- In a complete space, the type of closed subsets is complete for the
Hausdorff edistance. -/
instance closeds.complete_space [complete_space α] : complete_space (closeds α) :=
begin
/- We will show that, if a sequence of sets `s n` satisfies
`edist (s n) (s (n+1)) < 2^{-n}`, then it converges. This is enough to guarantee
completeness, by a standard completeness criterion.
We use the shorthand `B n = 2^{-n}` in ennreal. -/
let B : ℕ → ennreal := ennreal.half_pow,
/- Consider a sequence of closed sets `s n` with `edist (s n) (s (n+1)) < B n`.
We will show that it converges. The limit set is t0 = ⋂n, closure (⋃m≥n, s m).
We will have to show that a point in `s n` is close to a point in `t0`, and a point
in `t0` is close to a point in `s n`. The completeness then follows from a
standard criterion. -/
refine complete_of_convergent_controlled_sequences _ ennreal.half_pow_pos (λs hs, _),
let t0 := ⋂n, closure (⋃m≥n, (s m).val),
have : is_closed t0 := is_closed_Inter (λ_, is_closed_closure),
let t : closeds α := ⟨t0, this⟩,
use t,
have I1 : ∀n:ℕ, ∀x ∈ (s n).val, ∃y ∈ t0, edist x y ≤ 2 * B n,
{ /- This is the main difficulty of the proof. Starting from `x ∈ s n`, we want
to find a point in `t0` which is close to `x`. Define inductively a sequence of
points `z m` with `z n = x` and `z m ∈ s m` and `edist (z m) (z (m+1)) ≤ B m`. This is
possible since the Hausdorff distance between `s m` and `s (m+1)` is at most `B m`.
This sequence is a Cauchy sequence, therefore converging as the space is complete, to
a limit which satisfies the required properties. -/
assume n x hx,
haveI : nonempty α := ⟨x⟩,
let z : ℕ → α := λk, nat.rec_on k x (λl z, if l < n then x else
epsilon (λy, y ∈ (s (l+1)).val ∧ edist z y < B l)),
have z_le_n : ∀l≤n, z l = x,
{ assume l hl,
cases l with m,
{ show z 0 = x, from rfl },
{ have : z (nat.succ m) = ite (m < n) x (epsilon (λ (y : α), y ∈ (s (m + 1)).val ∧ edist (z m) y < B m))
:= rfl,
rw this,
simp [nat.lt_of_succ_le hl] }},
have : z n = x := z_le_n n (le_refl n),
-- check by induction that the sequence `z m` satisfies the required properties
have I : ∀m≥n, z m ∈ (s m).val → (z (m+1) ∈ (s (m+1)).val ∧ edist (z m) (z (m+1)) < B m),
{ assume m hm hz,
have E : ∃y, y ∈ (s (m+1)).val ∧ edist (z m) y < B m,
{ have : Hausdorff_edist (s m).val (s (m+1)).val < B m := hs m m (m+1) (le_refl _) (by simp),
rcases exists_edist_lt_of_Hausdorff_edist_lt hz this with ⟨y, hy, Dy⟩,
exact ⟨y, ⟨hy, Dy⟩⟩ },
have : z (m+1) = ite (m < n) x (epsilon (λ (y : α), y ∈ (s (m + 1)).val ∧ edist (z m) y < B m)) := rfl,
rw this,
simp only [not_lt_of_le hm, if_false],
exact epsilon_spec E },
have z_in_s : ∀m≥n, z m ∈ (s m).val :=
nat.le_induction (by rwa ‹z n = x›) (λm hm zm, (I m hm zm).1),
-- for all `m`, the distance between `z m` and `z (m+1)` is controlled by `B m`:
-- for `m ≥ n`, this follows from the construction, while for `m < n` all points are `x`.
have Im_succm : ∀m, edist (z m) (z (m+1)) ≤ B m,
{ assume m,
by_cases hm : n≤m,
{ exact le_of_lt (I m hm (z_in_s m hm)).2 },
{ rw not_le at hm,
have Im : z m = x := z_le_n m (le_of_lt hm),
have Im' : z (m+1) = x := z_le_n (m+1) (nat.succ_le_of_lt hm),
simp [Im, Im', ennreal.half_pow_pos] }},
/- From the distance control between `z m` and `z (m+1)`, we deduce a distance control
between `z k` and `z l` by summing the geometric series. -/
have Iz : ∀k l N, N ≤ k → N ≤ l → edist (z k) (z l) ≤ 2 * B N :=
λk l N hk hl, ennreal.edist_le_two_mul_half_pow hk hl Im_succm,
-- it follows from the previous bound that `z` is a Cauchy sequence
have : cauchy_seq z := ennreal.cauchy_seq_of_edist_le_half_pow Im_succm,
-- therefore, it converges
rcases cauchy_seq_tendsto_of_complete this with ⟨y, y_lim⟩,
-- the limit point `y` will be the desired point, in `t0` and close to our initial point `x`.
-- First, we check it belongs to `t0`.
have : y ∈ t0 := mem_Inter.2 (λk, mem_closure_of_tendsto (by simp) y_lim
begin
simp only [exists_prop, set.mem_Union, filter.mem_at_top_sets, set.mem_preimage, set.preimage_Union],
exact ⟨max n k, λm hm, ⟨m, ⟨le_trans (le_max_right _ _) hm, z_in_s m (le_trans (le_max_left _ _) hm)⟩⟩⟩,
end),
-- Then, we check that `y` is close to `x = z n`. This follows from the fact that `y`
-- is the limit of `z k`, and the distance between `z n` and `z k` has already been estimated.
have : edist x y ≤ 2 * B n,
{ refine le_of_tendsto (by simp) (tendsto_edist tendsto_const_nhds y_lim) _,
simp [‹z n = x›.symm],
exact ⟨n, λm hm, Iz n m n (le_refl n) hm⟩ },
-- Conclusion of this argument: the point `y` satisfies the required properties.
exact ⟨y, ‹y ∈ t0›, ‹edist x y ≤ 2 * B n›⟩ },
have I2 : ∀n:ℕ, ∀x ∈ t0, ∃y ∈ (s n).val, edist x y ≤ 2 * B n,
{ /- For the (much easier) reverse inequality, we start from a point `x ∈ t0` and we want
to find a point `y ∈ s n` which is close to `x`.
`x` belongs to `t0`, the intersection of the closures. In particular, it is well
approximated by a point `z` in `⋃m≥n, s m`, say in `s m`. Since `s m` and
`s n` are close, this point is itself well approximated by a point `y` in `s n`,
as required. -/
assume n x xt0,
have : x ∈ closure (⋃m≥n, (s m).val), by apply mem_Inter.1 xt0 n,
rcases mem_closure_iff'.1 this (B n) (ennreal.half_pow_pos n) with ⟨z, hz, Dxz⟩,
-- z : α, Dxz : edist x z < B n,
simp only [exists_prop, set.mem_Union] at hz,
rcases hz with ⟨m, ⟨m_ge_n, hm⟩⟩,
-- m : ℕ, m_ge_n : m ≥ n, hm : z ∈ (s m).val
have : Hausdorff_edist (s m).val (s n).val < B n := hs n m n m_ge_n (le_refl n),
rcases exists_edist_lt_of_Hausdorff_edist_lt hm this with ⟨y, hy, Dzy⟩,
-- y : α, hy : y ∈ (s n).val, Dzy : edist z y < B n
exact ⟨y, hy, calc
edist x y ≤ edist x z + edist z y : edist_triangle _ _ _
... ≤ B n + B n : add_le_add' (le_of_lt Dxz) (le_of_lt Dzy)
... = 2 * B n : (two_mul _).symm ⟩ },
-- Deduce from the above inequalities that the distance between `s n` and `t0` is at most `2 B n`.
have main : ∀n:ℕ, edist (s n) t ≤ 2 * B n := λn, Hausdorff_edist_le_of_mem_edist (I1 n) (I2 n),
-- from this, the convergence of `s n` to `t0` follows.
refine (tendsto_at_top _).2 (λε εpos, _),
have : tendsto (λn, 2 * ennreal.half_pow n) at_top (nhds (2 * 0)) :=
ennreal.tendsto_mul_right ennreal.half_pow_tendsto_zero (by simp),
rw mul_zero at this,
have Z := (tendsto_orderable.1 this).2 ε εpos,
simp only [filter.mem_at_top_sets, set.mem_set_of_eq] at Z,
rcases Z with ⟨N, hN⟩, -- ∀ (b : ℕ), b ≥ N → ε > 2 * B b
exact ⟨N, λn hn, lt_of_le_of_lt (main n) (hN n hn)⟩
end
/-- In a compact space, the type of closed subsets is compact. -/
instance closeds.compact_space [compact_space α] : compact_space (closeds α) :=
⟨begin
/- by completeness, it suffices to show that it is totally bounded,
i.e., for all ε>0, there is a finite set which is ε-dense.
start from a set `s` which is ε-dense in α. Then the subsets of `s`
are finitely many, and ε-dense for the Hausdorff distance. -/
refine compact_of_totally_bounded_is_closed (emetric.totally_bounded_iff.2 (λε εpos, _)) is_closed_univ,
rcases dense εpos with ⟨δ, δpos, δlt⟩,
rcases emetric.totally_bounded_iff.1 (compact_iff_totally_bounded_complete.1 (@compact_univ α _ _)).1 δ δpos
with ⟨s, fs, hs⟩,
-- s : set α, fs : finite s, hs : univ ⊆ ⋃ (y : α) (H : y ∈ s), eball y δ
-- we first show that any set is well approximated by a subset of `s`.
have main : ∀ u : set α, ∃v ⊆ s, Hausdorff_edist u v ≤ δ,
{ assume u,
let v := {x : α | x ∈ s ∧ ∃y∈u, edist x y < δ},
existsi [v, ((λx hx, hx.1) : v ⊆ s)],
refine Hausdorff_edist_le_of_mem_edist _ _,
{ assume x hx,
have : x ∈ ⋃y ∈ s, ball y δ := hs (by simp),
rcases mem_bUnion_iff.1 this with ⟨y, ⟨ys, dy⟩⟩,
have : edist y x < δ := by simp at dy; rwa [edist_comm] at dy,
exact ⟨y, ⟨ys, ⟨x, hx, this⟩⟩, le_of_lt dy⟩ },
{ rintros x ⟨hx1, ⟨y, yu, hy⟩⟩,
exact ⟨y, yu, le_of_lt hy⟩ }},
-- introduce the set F of all subsets of `s` (seen as members of `closeds α`).
let F := {f : closeds α | f.val ⊆ s},
use F,
split,
-- `F` is finite
{ apply @finite_of_finite_image _ _ F (λf, f.val),
{ apply set.inj_on_of_injective, simp [subtype.val_injective] },
{ refine finite_subset (finite_subsets_of_finite fs) (λb, _),
simp only [and_imp, set.mem_image, set.mem_set_of_eq, exists_imp_distrib],
assume x hx hx',
rwa hx' at hx }},
-- `F` is ε-dense
{ assume u _,
rcases main u.val with ⟨t0, t0s, Dut0⟩,
have : finite t0 := finite_subset fs t0s,
have : is_closed t0 := closed_of_compact _ (compact_of_finite this),
let t : closeds α := ⟨t0, this⟩,
have : t ∈ F := t0s,
have : edist u t < ε := lt_of_le_of_lt Dut0 δlt,
apply mem_bUnion_iff.2,
exact ⟨t, ‹t ∈ F›, this⟩ }
end⟩
/-- In an emetric space, the type of non-empty compact subsets is an emetric space,
where the edistance is the Hausdorff edistance -/
instance nonempty_compacts.emetric_space : emetric_space (nonempty_compacts α) :=
{ edist := λs t, Hausdorff_edist s.val t.val,
edist_self := λs, Hausdorff_edist_self,
edist_comm := λs t, Hausdorff_edist_comm,
edist_triangle := λs t u, Hausdorff_edist_triangle,
eq_of_edist_eq_zero := λs t h, subtype.eq $ begin
have : closure (s.val) = closure (t.val) := Hausdorff_edist_zero_iff_closure_eq_closure.1 h,
rwa [closure_eq_iff_is_closed.2 (closed_of_compact _ s.property.2),
closure_eq_iff_is_closed.2 (closed_of_compact _ t.property.2)] at this,
end }
/-- `nonempty_compacts.to_closeds` is a uniform embedding (as it is an isometry) -/
lemma nonempty_compacts.to_closeds.uniform_embedding :
uniform_embedding (@nonempty_compacts.to_closeds α _ _) :=
isometry.uniform_embedding $ λx y, rfl
/-- The range of `nonempty_compacts.to_closeds` is closed in a complete space -/
lemma nonempty_compacts.is_closed_in_closeds [complete_space α] :
is_closed (nonempty_compacts.to_closeds '' (univ : set (nonempty_compacts α))) :=
begin
have : nonempty_compacts.to_closeds '' univ = {s : closeds α | s.val ≠ ∅ ∧ compact s.val},
{ ext,
simp only [set.image_univ, set.mem_range, ne.def, set.mem_set_of_eq],
split,
{ rintros ⟨y, hy⟩,
have : x.val = y.val := by rcases hy; simp,
rw this,
exact y.property },
{ rintros ⟨hx1, hx2⟩,
existsi (⟨x.val, ⟨hx1, hx2⟩⟩ : nonempty_compacts α),
apply subtype.eq,
refl }},
rw this,
refine is_closed_of_closure_subset (λs hs, _),
split,
{ -- take a set set t which is nonempty and at distance at most 1 of s
rcases mem_closure_iff'.1 hs 1 ennreal.zero_lt_one with ⟨t, ht, Dst⟩,
rw edist_comm at Dst,
-- this set t contains a point x
rcases ne_empty_iff_exists_mem.1 ht.1 with ⟨x, hx⟩,
-- by the Hausdorff distance control, this point x is at distance at most 1
-- of a point y in s
rcases exists_edist_lt_of_Hausdorff_edist_lt hx Dst with ⟨y, hy, _⟩,
-- this shows that s is not empty
exact ne_empty_of_mem hy },
{ refine compact_iff_totally_bounded_complete.2 ⟨_, is_complete_of_is_closed s.property⟩,
refine totally_bounded_iff.2 (λε εpos, _),
-- we have to show that s is covered by finitely many eballs of radius ε
-- pick a nonempty compact set t at distance at most ε/2 of s
rcases mem_closure_iff'.1 hs (ε/2) (ennreal.half_pos εpos) with ⟨t, ht, Dst⟩,
-- cover this space with finitely many balls of radius ε/2
rcases totally_bounded_iff.1 (compact_iff_totally_bounded_complete.1 ht.2).1 (ε/2) (ennreal.half_pos εpos)
with ⟨u, fu, ut⟩,
refine ⟨u, ⟨fu, λx hx, _⟩⟩,
-- u : set α, fu : finite u, ut : t.val ⊆ ⋃ (y : α) (H : y ∈ u), eball y (ε / 2)
-- then s is covered by the union of the balls centered at u of radius ε
rcases exists_edist_lt_of_Hausdorff_edist_lt hx Dst with ⟨z, hz, Dxz⟩,
rcases mem_bUnion_iff.1 (ut hz) with ⟨y, hy, Dzy⟩,
have : edist x y < ε := calc
edist x y ≤ edist x z + edist z y : edist_triangle _ _ _
... < ε/2 + ε/2 : ennreal.add_lt_add Dxz Dzy
... = ε : ennreal.add_halves _,
exact mem_bUnion hy this },
end
/-- In a complete space, the type of nonempty compact subsets is complete. This follows
from the same statement for closed subsets -/
instance nonempty_compacts.complete_space [complete_space α] : complete_space (nonempty_compacts α) :=
begin
apply complete_space_of_is_complete_univ,
apply (is_complete_image_iff nonempty_compacts.to_closeds.uniform_embedding).1,
apply is_complete_of_is_closed,
exact nonempty_compacts.is_closed_in_closeds
end
/-- In a compact space, the type of nonempty compact subsets is compact. This follows from
the same statement for closed subsets -/
instance nonempty_compacts.compact_space [compact_space α] : compact_space (nonempty_compacts α) :=
⟨begin
rw compact_iff_compact_image_of_embedding nonempty_compacts.to_closeds.uniform_embedding.embedding,
exact compact_of_closed nonempty_compacts.is_closed_in_closeds
end⟩
/-- In a second countable space, the type of nonempty compact subsets is second countable -/
instance nonempty_compacts.second_countable_topology [second_countable_topology α] :
second_countable_topology (nonempty_compacts α) :=
begin
haveI : separable_space (nonempty_compacts α) :=
begin
/- To obtain a countable dense subset of `nonempty_compacts α`, start from
a countable dense subset `s` of α, and then consider all its finite nonempty subsets.
This set is countable and made of nonempty compact sets. It turns out to be dense:
by total boundedness, any compact set `t` can be covered by finitely many small balls, and
approximations in `s` of the centers of these balls give the required finite approximation
of `t`. -/
have : separable_space α := by apply_instance,
rcases this.exists_countable_closure_eq_univ with ⟨s, cs, s_dense⟩,
let v0 := {t : set α | finite t ∧ t ⊆ s},
let v : set (nonempty_compacts α) := {t : nonempty_compacts α | t.val ∈ v0},
refine ⟨⟨v, ⟨_, _⟩⟩⟩,
{ have : countable (subtype.val '' v),
{ refine countable_subset (λx hx, _) (countable_set_of_finite_subset cs),
rcases (mem_image _ _ _).1 hx with ⟨y, ⟨hy, yx⟩⟩,
rw ← yx,
exact hy },
apply countable_of_injective_of_countable_image _ this,
apply inj_on_of_inj_on_of_subset (injective_iff_inj_on_univ.1 subtype.val_injective)
(subset_univ _) },
{ refine subset.antisymm (subset_univ _) (λt ht, mem_closure_iff'.2 (λε εpos, _)),
-- t is a compact nonempty set, that we have to approximate uniformly by a a set in `v`.
rcases dense εpos with ⟨δ, δpos, δlt⟩,
-- construct a map F associating to a point in α an approximating point in s, up to δ/2.
have Exy : ∀x, ∃y, y ∈ s ∧ edist x y < δ/2,
{ assume x,
have : x ∈ closure s := by rw s_dense; exact mem_univ _,
rcases mem_closure_iff'.1 this (δ/2) (ennreal.half_pos δpos) with ⟨y, ys, hy⟩,
exact ⟨y, ⟨ys, hy⟩⟩ },
let F := λx, some (Exy x),
have Fspec : ∀x, F x ∈ s ∧ edist x (F x) < δ/2 := λx, some_spec (Exy x),
-- cover `t` with finitely many balls. Their centers form a set `a`
have : totally_bounded t.val := (compact_iff_totally_bounded_complete.1 t.property.2).1,
rcases totally_bounded_iff.1 this (δ/2) (ennreal.half_pos δpos) with ⟨a, af, ta⟩,
-- a : set α, af : finite a, ta : t.val ⊆ ⋃ (y : α) (H : y ∈ a), eball y (δ / 2)
-- replace each center by a nearby approximation in `s`, giving a new set `b`
let b := F '' a,
have : finite b := finite_image _ af,
have tb : ∀x ∈ t.val, ∃y ∈ b, edist x y < δ,
{ assume x hx,
rcases mem_bUnion_iff.1 (ta hx) with ⟨z, za, Dxz⟩,
existsi [F z, mem_image_of_mem _ za],
calc edist x (F z) ≤ edist x z + edist z (F z) : edist_triangle _ _ _
... < δ/2 + δ/2 : ennreal.add_lt_add Dxz (Fspec z).2
... = δ : ennreal.add_halves _ },
-- keep only the points in `b` that are close to point in `t`, yielding a new set `c`
let c := {y ∈ b | ∃x∈t.val, edist x y < δ},
have : finite c := finite_subset ‹finite b› (λx hx, hx.1),
-- points in `t` are well approximated by points in `c`
have tc : ∀x ∈ t.val, ∃y ∈ c, edist x y ≤ δ,
{ assume x hx,
rcases tb x hx with ⟨y, yv, Dxy⟩,
have : y ∈ c := by simp [c, -mem_image]; exact ⟨yv, ⟨x, hx, Dxy⟩⟩,
exact ⟨y, this, le_of_lt Dxy⟩ },
-- points in `c` are well approximated by points in `t`
have ct : ∀y ∈ c, ∃x ∈ t.val, edist y x ≤ δ,
{ rintros y ⟨hy1, ⟨x, xt, Dyx⟩⟩,
have : edist y x ≤ δ := calc
edist y x = edist x y : edist_comm _ _
... ≤ δ : le_of_lt Dyx,
exact ⟨x, xt, this⟩ },
-- it follows that their Hausdorff distance is small
have : Hausdorff_edist t.val c ≤ δ :=
Hausdorff_edist_le_of_mem_edist tc ct,
have Dtc : Hausdorff_edist t.val c < ε := lt_of_le_of_lt this δlt,
-- the set `c` is not empty, as it is well approximated by a nonempty set
have : c ≠ ∅,
{ by_contradiction h,
simp only [not_not, ne.def] at h,
rw [h, Hausdorff_edist_empty t.property.1] at Dtc,
exact not_top_lt Dtc },
-- let `d` be the version of `c` in the type `nonempty_compacts α`
let d : nonempty_compacts α := ⟨c, ⟨‹c ≠ ∅›, compact_of_finite ‹finite c›⟩⟩,
have : c ⊆ s,
{ assume x hx,
rcases (mem_image _ _ _).1 hx.1 with ⟨y, ⟨ya, yx⟩⟩,
rw ← yx,
exact (Fspec y).1 },
have : d ∈ v := ⟨‹finite c›, this⟩,
-- we have proved that `d` is a good approximation of `t` as requested
exact ⟨d, ‹d ∈ v›, Dtc⟩ },
end,
apply second_countable_of_separable,
end
end --section
end emetric --namespace
namespace metric
section
variables {α : Type u} [metric_space α]
/-- `nonempty_compacts α` inherits a metric space structure, as the Hausdorff
edistance between two such sets is finite. -/
instance nonempty_compacts.metric_space : metric_space (nonempty_compacts α) :=
emetric_space.to_metric_space $ λx y, Hausdorff_edist_ne_top_of_ne_empty_of_bounded x.2.1 y.2.1
(bounded_of_compact x.2.2) (bounded_of_compact y.2.2)
/-- The distance on `nonempty_compacts α` is the Hausdorff distance, by construction -/
lemma nonempty_compacts.dist_eq {x y : nonempty_compacts α} :
dist x y = Hausdorff_dist x.val y.val := rfl
lemma uniform_continuous_inf_dist_Hausdorff_dist :
uniform_continuous (λp : α × (nonempty_compacts α), inf_dist p.1 (p.2).val) :=
begin
refine uniform_continuous_of_le_add 2 _,
rintros ⟨x, s⟩ ⟨y, t⟩,
calc inf_dist x (s.val) ≤ inf_dist x (t.val) + Hausdorff_dist (t.val) (s.val) :
inf_dist_le_inf_dist_add_Hausdorff_dist (edist_ne_top t s)
... ≤ (inf_dist y (t.val) + dist x y) + Hausdorff_dist (t.val) (s.val) :
add_le_add_right inf_dist_le_inf_dist_add_dist _
... = inf_dist y (t.val) + (dist x y + Hausdorff_dist (s.val) (t.val)) :
by simp [add_comm, Hausdorff_dist_comm]
... ≤ inf_dist y (t.val) + (dist (x, s) (y, t) + dist (x, s) (y, t)) :
add_le_add_left (add_le_add (by simp [dist, le_refl]) (by simp [dist, nonempty_compacts.dist_eq, le_refl])) _
... = inf_dist y (t.val) + 2 * dist (x, s) (y, t) :
by rw [← mul_two, mul_comm]
end
end --section
end metric --namespace
|
96f1114ae5fc63d333495ba6208e4c80e7f94cfe | 4f643cce24b2d005aeeb5004c2316a8d6cc7f3b1 | /src/o_minimal/structure.lean | a787bb8e16e611b076332ca238c543fe57c2e994 | [] | no_license | rwbarton/lean-omin | da209ed061d64db65a8f7f71f198064986f30eb9 | fd733c6d95ef6f4743aae97de5e15df79877c00e | refs/heads/master | 1,674,408,673,325 | 1,607,343,535,000 | 1,607,343,535,000 | 285,150,399 | 9 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 6,998 | lean | import tactic.omega
import data.fin
import data.fintype.basic
import data.set.finite
import data.set.lattice
import for_mathlib.equiv
import for_mathlib.finvec
import for_mathlib.nat
open set
open_locale finvec
namespace o_minimal
variables (R : Type*)
/-- [vdD:1.2.1] A *structure* on a type R consists of
a class 𝑆ₙ of *definable* subsets of Rⁿ for each n ≥ 0
such that:
(S1) 𝑆ₙ is a boolean subalgebra of subsets of Rⁿ;
(S2) If A belongs to 𝑆ₙ then R × A and A × R belong to 𝑆ₙ₊₁;
(S3) For n ≥ 1, {(x₁, ..., xₙ) | x₁ = xₙ} belongs to 𝑆ₙ;
(S4) If A belongs to 𝑆ₙ₊₁ then π(A) belongs to Sₙ, where
π : Rⁿ⁺¹ → Rⁿ denotes the projection onto the first n coordinates. -/
structure struc :=
-- TODO: "generalize" to Type instead of Prop here?
-- TODO: Try this idea: (definable : (Σ {n : ℕ}, set (R^n)) → Prop)?
(definable : Π {n : ℕ} (A : set (finvec n R)), Prop)
(definable_empty (n : ℕ) :
definable (∅ : set (finvec n R)))
(definable_union {n : ℕ} {A B : set (finvec n R)} :
definable A → definable B → definable (A ∪ B))
(definable_compl {n : ℕ} {A : set (finvec n R)} :
definable A → definable Aᶜ)
(definable_r_prod {n : ℕ} {A : set (finvec n R)} :
definable A → definable (finvec.univ_prod 1 A))
(definable_prod_r {n : ℕ} {A : set (finvec n R)} :
definable A → definable (finvec.prod_univ A 1))
(definable_eq_outer {n : ℕ} :
definable ({x | x 0 = x.last} : set (finvec (n + 1) R)))
(definable_proj1 {n : ℕ} {A : set (finvec (n + 1) R)} :
definable A → definable (finvec.left '' A))
variables {R} (S : struc R)
lemma struc.convert_definable {n n' : ℕ}
{A : set (finvec n R)} {A' : set (finvec n' R)} (hA' : S.definable A')
(h : n = n') (e : ∀ x, x ∈ A ↔ finvec.cast h x ∈ A') :
S.definable A :=
begin
cases h,
convert hA',
ext x,
convert e x,
rw finvec.cast_id
end
lemma struc.definable_univ (n : ℕ) : S.definable (univ : set (finvec n R)) :=
begin
rw ←compl_empty,
exact S.definable_compl (S.definable_empty n)
end
lemma struc.definable_inter {n : ℕ} {A B : set (finvec n R)}
(hA : S.definable A) (hB : S.definable B) : S.definable (A ∩ B) :=
begin
rw inter_eq_compl_compl_union_compl,
exact S.definable_compl (S.definable_union (S.definable_compl hA) (S.definable_compl hB))
end
lemma struc.definable_diff {n : ℕ} {A B : set (finvec n R)}
(hA : S.definable A) (hB : S.definable B) : S.definable (A \ B) :=
begin
rw diff_eq,
exact S.definable_inter hA (S.definable_compl hB)
end
lemma struc.definable_Inter {ι : Type*} [fintype ι] {n : ℕ} {A : ι → set (finvec n R)}
(hA : ∀ i, S.definable (A i)) : S.definable (⋂ i, A i) :=
suffices ∀ {s : set ι}, set.finite s → S.definable (⋂ i ∈ s, A i),
by { convert this finite_univ, simp },
λ s hs, finite.induction_on hs
(by { convert S.definable_univ _, simp })
(λ i s _ _ IH, by { convert S.definable_inter (hA i) IH, simp })
lemma struc.definable_rn_prod {m n : ℕ} {A : set (finvec n R)}
(hA : S.definable A) : S.definable (finvec.univ_prod m A) :=
begin
induction m using nat.rec_plus_one with m IH,
{ exact (finvec.univ_prod_zero_like _).mpr hA },
{ exact (finvec.univ_prod_plus_one_like _).mpr (S.definable_r_prod IH) }
end
lemma struc.definable_prod_rn {n m : ℕ} {A : set (finvec n R)}
(hA : S.definable A) : S.definable (finvec.prod_univ A m) :=
begin
induction m with m IH,
{ rw finvec.prod_univ_zero_eq, exact hA },
{ rw finvec.prod_univ_plus_one_eq, exact S.definable_prod_r IH }
end
--- [vdD:1.2.2(i)]
lemma struc.definable_external_prod {n m : ℕ}
{A : set (finvec n R)} (hA : S.definable A)
{B : set (finvec m R)} (hB : S.definable B) : S.definable (A ⊠ B) :=
S.definable_inter (S.definable_prod_rn hA) (S.definable_rn_prod hB)
private lemma obvious_nat_lemma {n : ℕ} {i j : fin n} (h : i ≤ j) :
n = ↑i + (↑j - ↑i + 1 + (n - 1 - ↑j)) :=
begin
cases i with i,
cases j with j,
change i ≤ j at h,
dsimp,
omega
end
--- [vdD:1.2.2(ii)]
lemma struc.definable_eq {n : ℕ} (i j : fin n) :
S.definable {x | x i = x j} :=
begin
wlog h : i ≤ j using i j,
swap, { convert this, ext x, apply eq_comm },
have : S.definable
(finvec.univ_prod i (finvec.prod_univ {x : finvec ((j - i) + 1) R | x 0 = x (fin.last _)} (n - 1 - j))),
{ apply S.definable_rn_prod,
apply S.definable_prod_rn,
apply S.definable_eq_outer },
apply S.convert_definable this (obvious_nat_lemma h),
intro x,
simp only
[finvec.mem_prod_iff, true_and, and_true, mem_univ, mem_set_of_eq, function.comp_app],
congr'; ext,
{ simp, refl },
{ simpa using (nat.add_sub_cancel' h).symm }
end
lemma struc.definable_diag_rn {n : ℕ} :
S.definable {x : finvec (n + n) R | x.left = x.right} :=
begin
have : S.definable {x : finvec (n + n) R | ∀ (i : fin n), x.left i = x.right i},
{ convert_to S.definable (⋂ (i : fin n), {x : finvec (n + n) R | x.left i = x.right i}),
{ ext, simp },
exact S.definable_Inter (λ i, S.definable_eq _ _) },
convert this,
ext x,
apply function.funext_iff
end
lemma struc.definable_proj (S : struc R) {n m : ℕ} {A : set (finvec (n + m) R)}
(hA : S.definable A) : S.definable (finvec.left '' A) :=
begin
induction m with m IH,
-- Defeqs are in our favor, so just use `convert`.
{ convert hA,
convert set.image_id _,
ext x ⟨i,_⟩,
refl },
{ convert IH (S.definable_proj1 hA) using 1,
rw ←set.image_comp,
refl }
end
lemma struc.definable_reindex_aux {n m : ℕ} (σ : fin n → fin m)
{B : set (finvec n R)} (hB : S.definable B) :
S.definable {x : finvec (m + n) R | x.left ∘ σ = x.right ∧ x.right ∈ B} :=
begin
let Z : set (finvec (m + n) R) :=
(⋂ (i : fin n), {z | z ((σ i).cast_add _) = z (i.nat_add _)}) ∩ finvec.univ_prod m B,
have Zdef : ∀ (x : finvec m R) (y : finvec n R), x ++ y ∈ Z ↔ x ∘ σ = y ∧ y ∈ B,
{ intros x y,
simp only [set.mem_inter_iff, set.mem_Inter, set.mem_univ, finvec.univ_prod_eq,
finvec.append_mem_prod_iff, ←and_assoc, and_true],
congr',
rw [eq_iff_iff, function.funext_iff],
apply forall_congr,
intro j,
change (x ++ y).left (σ j) = (x ++ y).right j ↔ _,
simp },
have : S.definable Z :=
S.definable_inter (S.definable_Inter $ λ i, S.definable_eq _ _) (S.definable_rn_prod hB),
convert this,
ext z,
dsimp,
specialize Zdef (finvec.left z) (finvec.right z),
rw finvec.left_append_right at Zdef,
simp at Zdef,
simp [Zdef],
exact iff.rfl,
end
--- [vdD:1.2.2(iii)]
lemma struc.definable_reindex {n m : ℕ} (σ : fin n → fin m)
{B : set (finvec n R)} (hB : S.definable B) : S.definable {x | x ∘ σ ∈ B} :=
begin
convert (S.definable_proj (S.definable_reindex_aux σ hB)),
ext x,
rw ←finvec.append_equiv.symm.exists_congr_left,
rw prod.exists,
simp only [finvec.append_equiv_symm_app, finvec.left_append],
finish []
end
end o_minimal
|
b3b003d89e02efeb13feb7b5270e54540316c64a | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/tactic/assert_exists.lean | 876df3c4da70a4917023455e3603374e50bd90b1 | [
"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 | 5,370 | lean | /-
Copyright (c) 2022 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Patrick Massot, Scott Morrison
-/
import tactic.core
import tactic.lint.basic
/-!
# User commands for assert the (non-)existence of declaration or instances.
These commands are used to enforce the independence of different parts of mathlib.
## Implementation notes
This file provides two linters that verify that things we assert do not _yet_ exist do _eventually_
exist. This works by creating declarations of the form:
* ``assert_not_exists._checked.<uniq> : name := `foo`` for `assert_not_exists foo`
* `assert_no_instance._checked.<uniq> := t` for `assert_instance t`
These declarations are then picked up by the linter and analyzed accordingly.
The `_` in the `_checked` prefix should hide them from doc-gen.
-/
section
setup_tactic_parser
open tactic
/--
`assert_exists n` is a user command that asserts that a declaration named `n` exists
in the current import scope.
Be careful to use names (e.g. `rat`) rather than notations (e.g. `ℚ`).
-/
@[user_command]
meta def assert_exists (_ : parse $ tk "assert_exists") : lean.parser unit :=
do decl ← ident,
d ← get_decl decl,
return ()
/--
`assert_not_exists n` is a user command that asserts that a declaration named `n` *does not exist*
in the current import scope.
Be careful to use names (e.g. `rat`) rather than notations (e.g. `ℚ`).
It may be used (sparingly!) in mathlib to enforce plans that certain files
are independent of each other.
If you encounter an error on an `assert_not_exists` command while developing mathlib,
it is probably because you have introduced new import dependencies to a file.
In this case, you should refactor your work
(for example by creating new files rather than adding imports to existing files).
You should *not* delete the `assert_not_exists` statement without careful discussion ahead of time.
-/
@[user_command]
meta def assert_not_exists (_ : parse $ tk "assert_not_exists") : lean.parser unit :=
do
decl ← ident,
ff ← succeeds (get_decl decl) |
fail format!"Declaration {decl} is not allowed to exist in this file.",
n ← tactic.mk_fresh_name,
let marker := (`assert_not_exists._checked).append n,
add_decl
(declaration.defn marker [] `(name) `(decl) default tt),
pure ()
/-- A linter for checking that the declarations marked `assert_not_exists` eventually exist. -/
meta def assert_not_exists.linter : linter :=
{ test := λ d, (do
let n := d.to_name,
tt ← pure ((`assert_not_exists._checked).is_prefix_of n) | pure none,
declaration.defn _ _ `(name) val _ _ ← pure d,
n ← tactic.eval_expr name val,
tt ← succeeds (get_decl n) | pure (some (format!"`{n}` does not ever exist").to_string),
pure none),
auto_decls := tt,
no_errors_found := "All `assert_not_exists` declarations eventually exist.",
errors_found :=
"The following declarations used in `assert_not_exists` never exist; perhaps there is a typo.",
is_fast := tt }
/--
`assert_instance e` is a user command that asserts that an instance `e` is available
in the current import scope.
Example usage:
```
assert_instance semiring ℕ
```
-/
@[user_command]
meta def assert_instance (_ : parse $ tk "assert_instance") : lean.parser unit :=
do q ← texpr,
e ← i_to_expr q,
mk_instance e,
return ()
/--
`assert_no_instance e` is a user command that asserts that an instance `e` *is not available*
in the current import scope.
It may be used (sparingly!) in mathlib to enforce plans that certain files
are independent of each other.
If you encounter an error on an `assert_no_instance` command while developing mathlib,
it is probably because you have introduced new import dependencies to a file.
In this case, you should refactor your work
(for example by creating new files rather than adding imports to existing files).
You should *not* delete the `assert_no_instance` statement without careful discussion ahead of time.
Example usage:
```
assert_no_instance linear_ordered_field ℚ
```
-/
@[user_command]
meta def assert_no_instance (_ : parse $ tk "assert_no_instance") : lean.parser unit :=
do
q ← texpr,
e ← i_to_expr q,
i ← try_core (mk_instance e),
match i with
| none := do
n ← tactic.mk_fresh_name,
let marker := (`assert_no_instance._checked).append n,
et ← infer_type e,
tt ← succeeds (get_decl marker) |
add_decl
(declaration.defn marker [] et e default tt),
pure ()
| some i :=
(fail!"Instance `{i} : {e}` is not allowed to be found in this file." : tactic unit)
end
/-- A linter for checking that the declarations marked `assert_no_instance` eventually exist. -/
meta def assert_no_instance.linter : linter :=
{ test := λ d, (do
let n := d.to_name,
tt ← pure ((`assert_no_instance._checked).is_prefix_of n) | pure none,
declaration.defn _ _ _ val _ _ ← pure d,
tt ← succeeds (tactic.mk_instance val)
| (some ∘ format.to_string) <$> pformat!"No instance of `{val}`",
pure none),
auto_decls := tt,
no_errors_found := "All `assert_no_instance` instances eventually exist.",
errors_found :=
"The following typeclass instances used in `assert_no_instance` never exist; perhaps they " ++
"are missing?",
is_fast := ff }
end
|
19334bb0c9185dafbc5f93cebff6ec5d324b70b0 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/analysis/complex/polynomial.lean | 4e2e6dbb049e1a5b115d8eeb1aeb56d7b6197ac1 | [
"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 | 5,590 | 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 analysis.special_functions.pow
import field_theory.is_alg_closed.basic
import topology.algebra.polynomial
/-!
# The fundamental theorem of algebra
This file proves that every nonconstant complex polynomial has a root.
As a consequence, the complex numbers are algebraically closed.
-/
open complex polynomial metric filter is_absolute_value set
open_locale classical
namespace complex
/- The following proof uses the method given at
<https://ncatlab.org/nlab/show/fundamental+theorem+of+algebra#classical_fta_via_advanced_calculus>
-/
/-- **Fundamental theorem of algebra**: every non constant complex polynomial
has a root -/
lemma exists_root {f : polynomial ℂ} (hf : 0 < degree f) : ∃ z : ℂ, is_root f z :=
let ⟨z₀, hz₀⟩ := f.exists_forall_norm_le in
exists.intro z₀ $ classical.by_contradiction $ λ hf0,
have hfX : f - C (f.eval z₀) ≠ 0,
from mt sub_eq_zero.1 (λ h, not_le_of_gt hf (h.symm ▸ degree_C_le)),
let n := root_multiplicity z₀ (f - C (f.eval z₀)) in
let g := (f - C (f.eval z₀)) /ₘ ((X - C z₀) ^ n) in
have hg0 : g.eval z₀ ≠ 0, from eval_div_by_monic_pow_root_multiplicity_ne_zero _ hfX,
have hg : g * (X - C z₀) ^ n = f - C (f.eval z₀),
from div_by_monic_mul_pow_root_multiplicity_eq _ _,
have hn0 : 0 < n, from nat.pos_of_ne_zero $ λ hn0, by simpa [g, hn0] using hg0,
let ⟨δ', hδ'₁, hδ'₂⟩ := continuous_iff.1 (polynomial.continuous g) z₀
((g.eval z₀).abs) (complex.abs_pos.2 hg0) in
let δ := min (min (δ' / 2) 1) (((f.eval z₀).abs / (g.eval z₀).abs) / 2) in
have hf0' : 0 < (f.eval z₀).abs, from complex.abs_pos.2 hf0,
have hg0' : 0 < abs (eval z₀ g), from complex.abs_pos.2 hg0,
have hfg0 : 0 < (f.eval z₀).abs / abs (eval z₀ g), from div_pos hf0' hg0',
have hδ0 : 0 < δ, from lt_min (lt_min (half_pos hδ'₁) (by norm_num)) (half_pos hfg0),
have hδ : ∀ z : ℂ, abs (z - z₀) = δ → abs (g.eval z - g.eval z₀) < (g.eval z₀).abs,
from λ z hz, hδ'₂ z (by rw [complex.dist_eq, hz];
exact ((min_le_left _ _).trans (min_le_left _ _)).trans_lt (half_lt_self hδ'₁)),
have hδ1 : δ ≤ 1, from le_trans (min_le_left _ _) (min_le_right _ _),
let F : polynomial ℂ := C (f.eval z₀) + C (g.eval z₀) * (X - C z₀) ^ n in
let z' := (-f.eval z₀ * (g.eval z₀).abs * δ ^ n /
((f.eval z₀).abs * g.eval z₀)) ^ (n⁻¹ : ℂ) + z₀ in
have hF₁ : F.eval z' = f.eval z₀ - f.eval z₀ * (g.eval z₀).abs * δ ^ n / (f.eval z₀).abs,
by simp only [F, cpow_nat_inv_pow _ hn0, div_eq_mul_inv, eval_pow, mul_assoc,
mul_comm (g.eval z₀), mul_left_comm (g.eval z₀), mul_left_comm (g.eval z₀)⁻¹, mul_inv,
inv_mul_cancel hg0, eval_C, eval_add, eval_neg, sub_eq_add_neg, eval_mul, eval_X,
add_neg_cancel_right, neg_mul, mul_one, div_eq_mul_inv];
simp only [mul_comm, mul_left_comm, mul_assoc],
have hδs : (g.eval z₀).abs * δ ^ n / (f.eval z₀).abs < 1,
from (div_lt_one hf0').2 $ (lt_div_iff' hg0').1 $
calc δ ^ n ≤ δ ^ 1 : pow_le_pow_of_le_one (le_of_lt hδ0) hδ1 hn0
... = δ : pow_one _
... ≤ ((f.eval z₀).abs / (g.eval z₀).abs) / 2 : min_le_right _ _
... < _ : half_lt_self (div_pos hf0' hg0'),
have hF₂ : (F.eval z').abs = (f.eval z₀).abs - (g.eval z₀).abs * δ ^ n,
from calc (F.eval z').abs = (f.eval z₀ - f.eval z₀ * (g.eval z₀).abs
* δ ^ n / (f.eval z₀).abs).abs : congr_arg abs hF₁
... = abs (f.eval z₀) * complex.abs (1 - (g.eval z₀).abs * δ ^ n /
(f.eval z₀).abs : ℝ) : by rw [← complex.abs_mul];
exact congr_arg complex.abs
(by simp [mul_add, add_mul, mul_assoc, div_eq_mul_inv, sub_eq_add_neg])
... = _ : by rw [complex.abs_of_nonneg (sub_nonneg.2 (le_of_lt hδs)),
mul_sub, mul_div_cancel' _ (ne.symm (ne_of_lt hf0')), mul_one],
have hef0 : abs (eval z₀ g) * (eval z₀ f).abs ≠ 0,
from mul_ne_zero (mt complex.abs_eq_zero.1 hg0) (mt complex.abs_eq_zero.1 hf0),
have hz'z₀ : abs (z' - z₀) = δ,
by simp [z', mul_assoc, mul_left_comm _ (_ ^ n), mul_comm _ (_ ^ n),
mul_comm (eval z₀ f).abs, _root_.mul_div_cancel _ hef0, of_real_mul,
neg_mul, neg_div, is_absolute_value.abv_pow complex.abs,
complex.abs_of_nonneg (le_of_lt hδ0), real.pow_nat_rpow_nat_inv (le_of_lt hδ0) hn0],
have hF₃ : (f.eval z' - F.eval z').abs < (g.eval z₀).abs * δ ^ n,
from calc (f.eval z' - F.eval z').abs
= (g.eval z' - g.eval z₀).abs * (z' - z₀).abs ^ n :
by rw [← eq_sub_iff_add_eq.1 hg, ← is_absolute_value.abv_pow complex.abs,
← complex.abs_mul, sub_mul];
simp [F, eval_pow, eval_add, eval_mul, eval_sub, eval_C, eval_X, eval_neg, add_sub_cancel,
sub_eq_add_neg, add_assoc]
... = (g.eval z' - g.eval z₀).abs * δ ^ n : by rw hz'z₀
... < _ : (mul_lt_mul_right (pow_pos hδ0 _)).2 (hδ _ hz'z₀),
lt_irrefl (f.eval z₀).abs $
calc (f.eval z₀).abs ≤ (f.eval z').abs : hz₀ _
... = (F.eval z' + (f.eval z' - F.eval z')).abs : by simp
... ≤ (F.eval z').abs + (f.eval z' - F.eval z').abs : complex.abs_add _ _
... < (f.eval z₀).abs - (g.eval z₀).abs * δ ^ n + (g.eval z₀).abs * δ ^ n :
add_lt_add_of_le_of_lt (by rw hF₂) hF₃
... = (f.eval z₀).abs : sub_add_cancel _ _
instance is_alg_closed : is_alg_closed ℂ :=
is_alg_closed.of_exists_root _ $ λ p _ hp, complex.exists_root $ degree_pos_of_irreducible hp
end complex
|
7484fbfe7472b6a3bbb6cccd9e54bc7d6261d635 | 66a6486e19b71391cc438afee5f081a4257564ec | /homotopy/fwedge.hlean | c249aa2a8541b70928e8c5c1b8fa196acbeb74fa | [
"Apache-2.0"
] | permissive | spiceghello/Spectral | c8ccd1e32d4b6a9132ccee20fcba44b477cd0331 | 20023aa3de27c22ab9f9b4a177f5a1efdec2b19f | refs/heads/master | 1,611,263,374,078 | 1,523,349,717,000 | 1,523,349,717,000 | 92,312,239 | 0 | 0 | null | 1,495,642,470,000 | 1,495,642,470,000 | null | UTF-8 | Lean | false | false | 15,243 | hlean | /-
Copyright (c) 2016 Jakob von Raumer. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Floris van Doorn, Favonia
The Wedge Sum of a family of Pointed Types
-/
import homotopy.wedge ..move_to_lib ..choice ..pointed_pi
open eq is_equiv pushout pointed unit trunc_index sigma bool equiv choice unit is_trunc sigma.ops lift function pi prod
definition fwedge' {I : Type} (F : I → Type*) : Type := pushout (λi, ⟨i, Point (F i)⟩) (λi, ⋆)
definition pt' [constructor] {I : Type} {F : I → Type*} : fwedge' F := inr ⋆
definition fwedge [constructor] {I : Type} (F : I → Type*) : Type* := pointed.MK (fwedge' F) pt'
notation `⋁` := fwedge
namespace fwedge
variables {I : Type} {F : I → Type*}
definition il {i : I} (x : F i) : ⋁F := inl ⟨i, x⟩
definition inl (i : I) (x : F i) : ⋁F := il x
definition pinl [constructor] (i : I) : F i →* ⋁F := pmap.mk (inl i) (glue i)
definition glue (i : I) : inl i pt = pt :> ⋁ F := glue i
protected definition rec {P : ⋁F → Type} (Pinl : Π(i : I) (x : F i), P (il x))
(Pinr : P pt) (Pglue : Πi, pathover P (Pinl i pt) (glue i) (Pinr)) (y : fwedge' F) : P y :=
begin induction y, induction x, apply Pinl, induction x, apply Pinr, apply Pglue end
protected definition elim {P : Type} (Pinl : Π(i : I) (x : F i), P)
(Pinr : P) (Pglue : Πi, Pinl i pt = Pinr) (y : fwedge' F) : P :=
begin induction y with x u, induction x with i x, exact Pinl i x, induction u, apply Pinr, apply Pglue end
protected definition elim_glue {P : Type} {Pinl : Π(i : I) (x : F i), P}
{Pinr : P} (Pglue : Πi, Pinl i pt = Pinr) (i : I)
: ap (fwedge.elim Pinl Pinr Pglue) (fwedge.glue i) = Pglue i :=
!pushout.elim_glue
protected definition rec_glue {P : ⋁F → Type} {Pinl : Π(i : I) (x : F i), P (il x)}
{Pinr : P pt} (Pglue : Πi, pathover P (Pinl i pt) (glue i) (Pinr)) (i : I)
: apd (fwedge.rec Pinl Pinr Pglue) (fwedge.glue i) = Pglue i :=
!pushout.rec_glue
end fwedge
attribute fwedge.rec fwedge.elim [recursor 7] [unfold 7]
attribute fwedge.il fwedge.inl [constructor]
namespace fwedge
definition fwedge_of_wedge [unfold 3] {A B : Type*} (x : A ∨ B) : ⋁(bool.rec A B) :=
begin
induction x with a b,
{ exact inl ff a },
{ exact inl tt b },
{ exact glue ff ⬝ (glue tt)⁻¹ }
end
definition wedge_of_fwedge [unfold 3] {A B : Type*} (x : ⋁(bool.rec A B)) : A ∨ B :=
begin
induction x with b x b,
{ induction b, exact pushout.inl x, exact pushout.inr x },
{ exact pushout.inr pt },
{ induction b, exact pushout.glue ⋆, reflexivity }
end
definition wedge_pequiv_fwedge [constructor] (A B : Type*) : A ∨ B ≃* ⋁(bool.rec A B) :=
begin
fapply pequiv_of_equiv,
{ fapply equiv.MK,
{ exact fwedge_of_wedge },
{ exact wedge_of_fwedge },
{ exact abstract begin intro x, induction x with b x b,
{ induction b: reflexivity },
{ exact glue tt },
{ apply eq_pathover_id_right,
refine ap_compose fwedge_of_wedge _ _ ⬝ ap02 _ !elim_glue ⬝ph _,
induction b, exact !elim_glue ⬝ph whisker_bl _ hrfl, apply square_of_eq idp }
end end },
{ exact abstract begin intro x, induction x with a b,
{ reflexivity },
{ reflexivity },
{ apply eq_pathover_id_right,
refine ap_compose wedge_of_fwedge _ _ ⬝ ap02 _ !elim_glue ⬝ !ap_con ⬝
!elim_glue ◾ (!ap_inv ⬝ !elim_glue⁻²) ⬝ph _, exact hrfl } end end}},
{ exact glue ff }
end
definition is_contr_fwedge_of_neg {I : Type} (P : I → Type*) (H : ¬ I) : is_contr (⋁P) :=
begin
apply is_contr.mk pt, intro x, induction x, contradiction, reflexivity, contradiction
end
definition is_contr_fwedge_empty [instance] : is_contr (⋁empty.elim) :=
is_contr_fwedge_of_neg _ id
definition fwedge_pmap [constructor] {I : Type} {F : I → Type*} {X : Type*} (f : Πi, F i →* X) : ⋁F →* X :=
begin
fapply pmap.mk,
{ intro x, induction x,
exact f i x,
exact pt,
exact respect_pt (f i) },
{ reflexivity }
end
definition wedge_pmap [constructor] {A B : Type*} {X : Type*} (f : A →* X) (g : B →* X) : (A ∨ B) →* X :=
begin
fapply pmap.mk,
{ intro x, induction x, exact (f a), exact (g a), exact (respect_pt (f) ⬝ (respect_pt g)⁻¹) },
{ exact respect_pt f }
end
definition fwedge_pmap_beta [constructor] {I : Type} {F : I → Type*} {X : Type*} (f : Πi, F i →* X) (i : I) :
fwedge_pmap f ∘* pinl i ~* f i :=
begin
fapply phomotopy.mk,
{ reflexivity },
{ exact !idp_con ⬝ !fwedge.elim_glue⁻¹ }
end
definition fwedge_pmap_eta [constructor] {I : Type} {F : I → Type*} {X : Type*} (g : ⋁F →* X) :
fwedge_pmap (λi, g ∘* pinl i) ~* g :=
begin
fapply phomotopy.mk,
{ intro x, induction x,
reflexivity,
exact (respect_pt g)⁻¹,
apply eq_pathover, refine !elim_glue ⬝ph _, apply whisker_lb, exact hrfl },
{ exact con.left_inv (respect_pt g) }
end
definition fwedge_pmap_pinl [constructor] {I : Type} {F : I → Type*} : fwedge_pmap (λi, pinl i) ~* pid (⋁ F) :=
begin
fapply phomotopy.mk,
{ intro x, induction x,
reflexivity, reflexivity,
apply eq_pathover, apply hdeg_square, refine !elim_glue ⬝ !ap_id⁻¹ },
{ reflexivity }
end
definition fwedge_pmap_equiv [constructor] {I : Type} (F : I → Type*) (X : Type*) :
⋁F →* X ≃ Πi, F i →* X :=
begin
fapply equiv.MK,
{ intro g i, exact g ∘* pinl i },
{ exact fwedge_pmap },
{ intro f, apply eq_of_homotopy, intro i, apply eq_of_phomotopy, apply fwedge_pmap_beta f i },
{ intro g, apply eq_of_phomotopy, exact fwedge_pmap_eta g }
end
definition wedge_pmap_equiv [constructor] (A B X : Type*) :
((A ∨ B) →* X) ≃ ((A →* X) × (B →* X)) :=
calc (A ∨ B) →* X ≃ ⋁(bool.rec A B) →* X : by exact pequiv_ppcompose_right (wedge_pequiv_fwedge A B)⁻¹ᵉ*
... ≃ Πi, (bool.rec A B) i →* X : by exact fwedge_pmap_equiv (bool.rec A B) X
... ≃ (A →* X) × (B →* X) : by exact pi_bool_left (λ i, bool.rec A B i →* X)
definition fwedge_pmap_nat₂ {I : Type}(F : I → Type*){X Y : Type*}
(f : X →* Y) (h : Πi, F i →* X) (w : fwedge F) :
(f ∘* (fwedge_pmap h)) w = fwedge_pmap (λi, f ∘* (h i)) w :=
begin
induction w, reflexivity,
refine !respect_pt,
apply eq_pathover,
refine ap_compose f (fwedge_pmap h) _ ⬝ph _,
refine ap (ap f) !elim_glue ⬝ph _,
refine _ ⬝hp !elim_glue⁻¹, esimp,
apply whisker_br,
apply !hrefl
end
-- making the maps in hsquare 1:
-- top and bottom:
definition prod_pi_bool_comp_funct {A B : Type*}(X : Type*) : (A →* X) × (B →* X) → Π u, (bool.rec A B u →* X) :=
begin
refine equiv.symm _,
fapply pi_bool_left
end
-- left:
definition prod_funct_comp {A B X Y : Type*} (f : X →* Y) : (A →* X) × (B →* X) → (A →* Y) × (B →* Y) :=
prod_functor (pcompose f) (pcompose f)
-- right:
definition left_comp_pi_bool_funct {A B X Y : Type*} (f : X →* Y) : (Π u, (bool.rec A B u →* X)) → (Π u, (bool.rec A B u →* Y)) :=
begin
intro, intro, exact f ∘* (a u)
end
definition left_comp_pi_bool {A B X Y : Type*} (f : X →* Y) : Π u, ((bool.rec A B u →* X) → (bool.rec A B u →* Y)) :=
begin
intro, intro, exact f∘* a
end
-- hsquare 1:
definition prod_to_pi_bool_nat_square {A B X Y : Type*} (f : X →* Y) :
hsquare (prod_pi_bool_comp_funct X) (prod_pi_bool_comp_funct Y) (prod_funct_comp f) (@left_comp_pi_bool_funct A B X Y f) :=
begin
intro x, fapply eq_of_homotopy, intro u, induction u, esimp, esimp
end
-- hsquare 2:
definition fwedge_pmap_nat_square {A B X Y : Type*} (f : X →* Y) :
hsquare (fwedge_pmap_equiv (bool.rec A B) X)⁻¹ᵉ (fwedge_pmap_equiv (bool.rec A B) Y)⁻¹ᵉ (left_comp_pi_bool_funct f) (pcompose f) :=
begin
intro h, esimp, fapply eq_of_phomotopy, fapply phomotopy.mk,
exact fwedge_pmap_nat₂ (λ u, bool.rec A B u) f h,
reflexivity
end
-- hsquare 3:
definition fwedge_to_wedge_nat_square {A B X Y : Type*} (f : X →* Y) :
hsquare (pequiv_ppcompose_right (wedge_pequiv_fwedge A B)) (pequiv_ppcompose_right (wedge_pequiv_fwedge A B)) (pcompose f) (pcompose f) :=
begin
exact sorry
end
definition wedge_pmap_nat₂ (A B X Y : Type*) (f : X →* Y) (h : A →* X) (k : B →* X) : Π (w : A ∨ B),
(f ∘* (wedge_pmap h k)) w = wedge_pmap (f ∘* h )(f ∘* k) w :=
have H : _, from
(@prod_to_pi_bool_nat_square A B X Y f) ⬝htyh (fwedge_pmap_nat_square f) ⬝htyh (fwedge_to_wedge_nat_square f),
sorry
-- SA to here 7/5
definition fwedge_pmap_phomotopy {I : Type} {F : I → Type*} {X : Type*} {f g : Π i, F i →* X}
(h : Π i, f i ~* g i) : fwedge_pmap f ~* fwedge_pmap g :=
begin
fconstructor,
{ fapply fwedge.rec,
{ exact h },
{ reflexivity },
{ intro i, apply eq_pathover,
refine _ ⬝ph _ ⬝hp _,
{ exact (respect_pt (g i)) },
{ exact (respect_pt (f i)) },
{ exact !elim_glue },
{ apply square_of_eq,
exact ((phomotopy.sigma_char (f i) (g i)) (h i)).2
},
{ refine !elim_glue⁻¹ }
}
},
{ reflexivity }
end
open trunc
definition trunc_fwedge_pmap_equiv.{u} {n : ℕ₋₂} {I : Type.{u}} (H : has_choice n I)
(F : I → pType.{u}) (X : pType.{u}) : trunc n (⋁F →* X) ≃ Πi, trunc n (F i →* X) :=
trunc_equiv_trunc n (fwedge_pmap_equiv F X) ⬝e choice_equiv (λi, F i →* X)
definition fwedge_functor [constructor] {I : Type} {F F' : I → Type*} (f : Π i, F i →* F' i)
: ⋁ F →* ⋁ F' := fwedge_pmap (λ i, pinl i ∘* f i)
definition fwedge_functor_pid {I : Type} {F : I → Type*}
: @fwedge_functor I F F (λ i, !pid) ~* !pid :=
calc fwedge_pmap (λ i, pinl i ∘* !pid) ~* fwedge_pmap pinl : by exact fwedge_pmap_phomotopy (λ i, pcompose_pid (pinl i))
... ~* fwedge_pmap (λ i, !pid ∘* pinl i) : by exact fwedge_pmap_phomotopy (λ i, phomotopy.symm (pid_pcompose (pinl i)))
... ~* !pid : by exact fwedge_pmap_eta !pid
definition fwedge_functor_pcompose {I : Type} {F F' F'' : I → Type*} (g : Π i, F' i →* F'' i)
(f : Π i, F i →* F' i) : fwedge_functor (λ i, g i ∘* f i) ~* fwedge_functor g ∘* fwedge_functor f :=
calc fwedge_functor (λ i, g i ∘* f i)
~* fwedge_pmap (λ i, (pinl i ∘* g i) ∘* f i)
: by exact fwedge_pmap_phomotopy (λ i, phomotopy.symm (passoc (pinl i) (g i) (f i)))
... ~* fwedge_pmap (λ i, (fwedge_functor g ∘* pinl i) ∘* f i)
: by exact fwedge_pmap_phomotopy (λ i, pwhisker_right (f i) (phomotopy.symm (fwedge_pmap_beta (λ i, pinl i ∘* g i) i)))
... ~* fwedge_pmap (λ i, fwedge_functor g ∘* (pinl i ∘* f i))
: by exact fwedge_pmap_phomotopy (λ i, passoc (fwedge_functor g) (pinl i) (f i))
... ~* fwedge_pmap (λ i, fwedge_functor g ∘* (fwedge_functor f ∘* pinl i))
: by exact fwedge_pmap_phomotopy (λ i, pwhisker_left (fwedge_functor g) (phomotopy.symm (fwedge_pmap_beta (λ i, pinl i ∘* f i) i)))
... ~* fwedge_pmap (λ i, (fwedge_functor g ∘* fwedge_functor f) ∘* pinl i)
: by exact fwedge_pmap_phomotopy (λ i, (phomotopy.symm (passoc (fwedge_functor g) (fwedge_functor f) (pinl i))))
... ~* fwedge_functor g ∘* fwedge_functor f
: by exact fwedge_pmap_eta (fwedge_functor g ∘* fwedge_functor f)
definition fwedge_functor_phomotopy {I : Type} {F F' : I → Type*} {f g : Π i, F i →* F' i}
(h : Π i, f i ~* g i) : fwedge_functor f ~* fwedge_functor g :=
fwedge_pmap_phomotopy (λ i, pwhisker_left (pinl i) (h i))
definition fwedge_pequiv [constructor] {I : Type} {F F' : I → Type*} (f : Π i, F i ≃* F' i) : ⋁ F ≃* ⋁ F' :=
let pto := fwedge_functor (λ i, f i) in
let pfrom := fwedge_functor (λ i, (f i)⁻¹ᵉ*) in
begin
fapply pequiv_of_pmap, exact pto,
fapply adjointify, exact pfrom,
{ intro y, refine (fwedge_functor_pcompose (λ i, f i) (λ i, (f i)⁻¹ᵉ*) y)⁻¹ ⬝ _,
refine fwedge_functor_phomotopy (λ i, pright_inv (f i)) y ⬝ _,
exact fwedge_functor_pid y
},
{ intro y, refine (fwedge_functor_pcompose (λ i, (f i)⁻¹ᵉ*) (λ i, f i) y)⁻¹ ⬝ _,
refine fwedge_functor_phomotopy (λ i, pleft_inv (f i)) y ⬝ _,
exact fwedge_functor_pid y
}
end
definition plift_fwedge.{u v} {I : Type} (F : I → pType.{u}) : plift.{u v} (⋁ F) ≃* ⋁ (plift.{u v} ∘ F) :=
calc plift.{u v} (⋁ F) ≃* ⋁ F : by exact !pequiv_plift ⁻¹ᵉ*
... ≃* ⋁ (λ i, plift.{u v} (F i)) : by exact fwedge_pequiv (λ i, !pequiv_plift)
definition fwedge_down_left.{u v} {I : Type} (F : I → pType) : ⋁ (F ∘ down.{u v}) ≃* ⋁ F :=
proof
let pto := @fwedge_pmap (lift.{u v} I) (F ∘ down) (⋁ F) (λ i, pinl (down i)) in
let pfrom := @fwedge_pmap I F (⋁ (F ∘ down.{u v})) (λ i, pinl (up.{u v} i)) in
begin
fapply pequiv_of_pmap,
{ exact pto },
fapply adjointify,
{ exact pfrom },
{ intro x, exact calc pto (pfrom x) = fwedge_pmap (λ i, (pto ∘* pfrom) ∘* pinl i) x : by exact (fwedge_pmap_eta (pto ∘* pfrom) x)⁻¹
... = fwedge_pmap (λ i, pto ∘* (pfrom ∘* pinl i)) x : by exact fwedge_pmap_phomotopy (λ i, passoc pto pfrom (pinl i)) x
... = fwedge_pmap (λ i, pto ∘* pinl (up.{u v} i)) x : by exact fwedge_pmap_phomotopy (λ i, pwhisker_left pto (fwedge_pmap_beta (λ i, pinl (up.{u v} i)) i)) x
... = fwedge_pmap pinl x : by exact fwedge_pmap_phomotopy (λ i, fwedge_pmap_beta (λ i, (pinl (down.{u v} i))) (up.{u v} i)) x
... = x : by exact fwedge_pmap_pinl x
},
{ intro x, exact calc pfrom (pto x) = fwedge_pmap (λ i, (pfrom ∘* pto) ∘* pinl i) x : by exact (fwedge_pmap_eta (pfrom ∘* pto) x)⁻¹
... = fwedge_pmap (λ i, pfrom ∘* (pto ∘* pinl i)) x : by exact fwedge_pmap_phomotopy (λ i, passoc pfrom pto (pinl i)) x
... = fwedge_pmap (λ i, pfrom ∘* pinl (down.{u v} i)) x : by exact fwedge_pmap_phomotopy (λ i, pwhisker_left pfrom (fwedge_pmap_beta (λ i, pinl (down.{u v} i)) i)) x
... = fwedge_pmap pinl x : by exact fwedge_pmap_phomotopy (λ i,
begin induction i with i,
exact fwedge_pmap_beta (λ i, (pinl (up.{u v} i))) i
end
) x
... = x : by exact fwedge_pmap_pinl x
}
end
qed
end fwedge
|
f3dcdf1ec5312263bd52bdd47baae7c745b911fb | df7bb3acd9623e489e95e85d0bc55590ab0bc393 | /lean/love07_metaprogramming_exercise_solution.lean | b415e418010f99b219e2dd17eef0c1e6bc0e4291 | [] | no_license | MaschavanderMarel/logical_verification_2020 | a41c210b9237c56cb35f6cd399e3ac2fe42e775d | 7d562ef174cc6578ca6013f74db336480470b708 | refs/heads/master | 1,692,144,223,196 | 1,634,661,675,000 | 1,634,661,675,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 9,504 | lean | import .love07_metaprogramming_demo
/- # LoVe Exercise 7: Metaprogramming -/
set_option pp.beta true
set_option pp.generalized_field_notation false
namespace LoVe
/- ## Question 1: A Term Exploder
In this exercise, we develop a string format for the `expr` metatype. By
default, there is no `has_repr` instance to print a nice string. For example: -/
#eval (expr.app (expr.var 0) (expr.var 1) : expr) -- result: `[external]`
#eval (`(λx : ℕ, x + x) : expr) -- result: `[external]`
/- 1.1. Define a metafunction `expr.repr` that converts an `expr` into a
`string`. It is acceptable to leave out some fields from the `expr`
constructors, such as the level `l` of a sort, the binder information `bi` of
a `λ` or `∀` binder, and the arguments of the `macro` constructor.
Hint: Use `name.to_string` to convert a name to a string, and `repr` for other
types that belong to the `has_repr` type class. -/
meta def expr.repr : expr → string
| (expr.var n) := "(var " ++ repr n ++ ")"
| (expr.sort l) := "sort"
| (expr.const n ls) := "(const " ++ n.to_string ++ ")"
| (expr.mvar n m t) :=
"(mvar " ++ name.to_string n ++ " " ++ name.to_string m ++ " " ++
expr.repr t ++ ")"
| (expr.local_const n m bi t) :=
"(local_const " ++ name.to_string n ++ " " ++ name.to_string m ++ " " ++
expr.repr t ++ ")"
| (expr.app e f) :=
"(app " ++ expr.repr e ++ " " ++ expr.repr f ++ ")"
| (expr.lam n bi e t) :=
"(lam " ++ name.to_string n ++ " " ++ expr.repr e ++ " " ++ expr.repr t ++ ")"
| (expr.pi n bi e t) :=
"(pi " ++ name.to_string n ++ " " ++ expr.repr e ++ " " ++ expr.repr t ++ ")"
| (expr.elet n g e f) :=
"(elet " ++ name.to_string n ++ " " ++ expr.repr g ++ " " ++ expr.repr e ++
" " ++ expr.repr f ++ ")"
| (expr.macro d args) := "macro"
/- We register `expr.repr` in the `has_repr` type class, so that we can use
`repr` without qualification in the future, and so that it is available to
`#eval`. We need the `meta` keyword in front of the command we enter. -/
meta instance expr.has_repr : has_repr expr :=
{ repr := expr.repr }
/- 1.2. Test your setup. -/
#eval (expr.app (expr.var 0) (expr.var 1) : expr)
#eval (`(λx : ℕ, x + x) : expr)
/- 1.3. Compare your answer with `expr.to_raw_fmt`. -/
#check expr.to_raw_fmt
/- ## Question 2: `destruct_and` on Steroids
Recall from the lecture that `destruct_and` fails on easy goals such as -/
lemma abc_ac₂ (a b c : Prop) (h : a ∧ b ∧ c) :
a ∧ c :=
sorry
/- We will now address this by developing a new tactic called `destro_and`,
which applies both **des**truction and in**tro**duction rules for conjunction.
It will also go automatically through the hypotheses instead of taking an
argument. We will develop it in three steps.
2.1. Develop a tactic `intro_ands` that replaces all goals of the form
`a ∧ b` with two new goals `a` and `b` systematically, until all top-level
conjunctions are gone.
For this, we can use tactics such as `tactic.repeat` (which repeatedly applies a
tactic on all goals and subgoals until the tactic fails on each of the goal) and
`tactic.applyc` (which can be used to apply a rule, in connection with backtick
quoting). -/
meta def intro_ands : tactic unit :=
tactic.repeat (tactic.applyc `and.intro)
lemma abcd_bd (a b c d : Prop) (h : a ∧ (b ∧ c) ∧ d) :
b ∧ d :=
begin
intro_ands,
/- The proof state should be as follows:
2 goals
a b c d : Prop,
h : a ∧ (b ∧ c) ∧ d
⊢ b
a b c d : Prop,
h : a ∧ (b ∧ c) ∧ d
⊢ d -/
repeat { sorry }
end
lemma abcd_bacb (a b c d : Prop) (h : a ∧ (b ∧ c) ∧ d) :
b ∧ (a ∧ (c ∧ b)) :=
begin
intro_ands,
/- The proof state should be as follows:
4 goals
a b c d : Prop,
h : a ∧ (b ∧ c) ∧ d
⊢ b
a b c d : Prop,
h : a ∧ (b ∧ c) ∧ d
⊢ a
a b c d : Prop,
h : a ∧ (b ∧ c) ∧ d
⊢ c
a b c d : Prop,
h : a ∧ (b ∧ c) ∧ d
⊢ b -/
repeat { sorry }
end
/- 2.2. Develop a tactic `destruct_ands` that replaces hypotheses of the form
`h : a ∧ b` by two new hypotheses `h_left : a` and `h_right : b` systematically,
until all top-level conjunctions are gone.
Here is imperative-style pseudocode that you can follow:
1. Retrieve the list of hypotheses from the context. This is provided by the
metaconstant `local_context`.
2. Find the first hypothesis (= term) with a type (= proposition) of the form
`_ ∧ _`. Here, you can use the `list.mfirst` function, in conjunction with
pattern matching. You can use `infer_type` to query the type of a term.
3. Perform a case split on the first found hypothesis. This can be achieved
using the `cases` metafunction.
4. Repeat.
The above procedure might fail if there exists no hypotheses of the required
form. Make sure to handle this failure gracefully, for example using
`tactic.try` or `<|> pure ()`. -/
meta def destruct_ands : tactic unit :=
tactic.repeat (do
hs ← tactic.local_context,
h ← list.mfirst (λh, do `(_ ∧ _) ← tactic.infer_type h, pure h) hs,
tactic.cases h,
pure ())
-- Alternative solutions:
meta def destruct_ands₂ : tactic unit :=
tactic.try
(do
hs ← tactic.local_context,
h ← list.mfirst (λh, do `(_ ∧ _) ← tactic.infer_type h, pure h) hs,
tactic.cases h,
destruct_ands₂)
meta def destruct_ands₃ : tactic unit :=
(do
hs ← tactic.local_context,
h ← list.mfirst (λh, do `(_ ∧ _) ← tactic.infer_type h, pure h) hs,
tactic.cases h,
destruct_ands₃)
<|> pure ()
lemma abcd_bd₂ (a b c d : Prop) (h : a ∧ (b ∧ c) ∧ d) :
b ∧ d :=
begin
destruct_ands,
/- The proof state should be as follows:
a b c d : Prop,
h_left : a,
h_right_right : d,
h_right_left_left : b,
h_right_left_right : c
⊢ b ∧ d -/
sorry
end
/- 2.3. Combine the two tactics developed above and `tactic.assumption` to
implement the desired `destro_and` tactic. -/
meta def destro_and : tactic unit :=
do
destruct_ands,
intro_ands,
tactic.all_goals (tactic.try tactic.assumption),
pure ()
lemma abcd_bd₃ (a b c d : Prop) (h : a ∧ (b ∧ c) ∧ d) :
b ∧ d :=
by destro_and
lemma abcd_bacb₂ (a b c d : Prop) (h : a ∧ (b ∧ c) ∧ d) :
b ∧ (a ∧ (c ∧ b)) :=
by destro_and
lemma abd_bacb (a b c d : Prop) (h : a ∧ b ∧ d) :
b ∧ (a ∧ (c ∧ b)) :=
begin
destro_and,
/- The proof state should be roughly as follows:
a b c d : Prop,
h_left : a,
h_right_left : b,
h_right_right : d
⊢ c -/
sorry -- unprovable
end
/- 2.4. Provide some more examples for `destro_and` to convince yourself that
it works as expected also on more complicated examples. -/
lemma ab (a b : Prop) (h : a ∨ b) :
a ∨ b :=
by destro_and
lemma abcdef_1 (a b c d e f : Prop) (h : a ∧ b ∧ c ∧ d ∧ e ∧ f) :
f ∧ e ∧ f ∧ a ∧ d ∧ b ∧ c ∧ a :=
by destro_and
lemma abcdef_2 (a b c d e f : Prop) (h : a ∧ ((b ∧ ((c ∧ d) ∧ e)) ∧ f)) :
f ∧ e ∧ f ∧ a ∧ d ∧ b ∧ c ∧ a :=
by destro_and
lemma abcdef_3 (a b c d e f : Prop) (h : a ∧ (b ∧ (c ∧ (d ∧ e ∧ f)))) :
f ∧ (e ∧ (f ∧ (a ∧ d ∧ b ∧ c ∧ a))) :=
by destro_and
/- ## Question 3 (**optional**): A Theorem Finder
We will implement a function that allows us to find theorems by constants
appearing in their statements. So given a list of constant names, the function
will list all theorems in which all these constants appear.
You can use the following metaconstants:
* `declaration` contains all data (name, type, value) associated with a
declaration understood broadly (e.g., axiom, lemma, constant, etc.).
* `tactic.get_env` gives us access to the `environment`, a metatype that lists
all `declaration`s (including all theorems).
* `environment.fold` allows us to walk through the environment and collect data.
* `expr.fold` allows us to walk through an expression and collect data.
3.1 (**optional**). Write a metafunction that checks whether an expression
contains a specific constant.
You can use `expr.fold` to walk through the expression, `||` and `ff` for
Booleans, and `expr.is_constant_of` to check whether an expression is a
constant. -/
meta def term_contains (e : expr) (nam : name) : bool :=
expr.fold e ff (λe' d c, c || expr.is_constant_of e' nam)
/- 3.2 (**optional**). Write a metafunction that checks whether an expression
contains **all** constants in a list.
You can use `list.band` (Boolean and). -/
meta def term_contains_all (nams : list name) (e : expr) : bool :=
list.band (list.map (term_contains e) nams)
/- 3.3 (**optional**). Produce the list of all theorems that contain all
constants `nams` in their statement.
`environment.fold` allows you to walk over the list of declarations. With
`declaration.type`, you get the type of a theorem, and with
`declaration.to_name` you get the name. -/
meta def list_constants (nams : list name) (e : environment) : list name :=
environment.fold e [] (λdecl nams',
if term_contains_all nams decl.type then decl.to_name :: nams' else nams')
/- Finally, we develop a tactic that uses the above metafunctions to log all
found theorems: -/
meta def find_constants (nams : list name) : tactic unit :=
do
env ← tactic.get_env,
list.mmap' tactic.trace (list_constants nams env)
/- We test the solution. -/
run_cmd find_constants [] -- lists all theorems
run_cmd find_constants [`list.map, `function.comp]
end LoVe
|
f6c461f786fd2d54df69611c6f7abb9fec294df0 | 43390109ab88557e6090f3245c47479c123ee500 | /src/Topology/Material/pasting_lemma.lean | b7124eb13c208a6c8f83fd1e4ee68666bc659bd3 | [
"Apache-2.0"
] | permissive | Ja1941/xena-UROP-2018 | 41f0956519f94d56b8bf6834a8d39473f4923200 | b111fb87f343cf79eca3b886f99ee15c1dd9884b | refs/heads/master | 1,662,355,955,139 | 1,590,577,325,000 | 1,590,577,325,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 5,310 | lean | /-
Copyright (c) 2018 Luca Gerolla. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kevin Buzzard, Mario Carneiro, Luca Gerolla
Prove part of pasting lemma (ex 10.7 Sutherland) for continuity proofs
-/
import data.set.basic
import analysis.topology.continuity
open set
definition restriction {X Y : Type*} (f : X → Y) (A : set X) : A → Y :=
λ a, f a.val
lemma preimage_sub (X Y : Type*) (f : X → Y) (C : set Y) (A : set X) :
(restriction f A) ⁻¹' C = { a : A | a.val ∈ f⁻¹' C} := by finish
lemma and_congr_right_iff {a b c : Prop} : (a ∧ b ↔ a ∧ c) ↔ (a → (b ↔ c)) :=
⟨λ h ha, by simp [ha] at h; exact h, and_congr_right⟩
theorem handy (X : Type*) (U A B : set X) :
U ∩ A = U ∩ B ↔ {u : U | u.val ∈ A} = {u : U | u.val ∈ B} :=
sorry
--by simp [set.set_eq_def, and_congr_right_iff]
lemma restriction_closed {X Y : Type*} (f : X → Y) [topological_space X] [topological_space Y]
(A : set X) (C : set Y) (HAcont : continuous (restriction f A))
(HAclosed : is_closed A) (HCclosed : is_closed C) : is_closed (f ⁻¹' C ∩ A) :=
begin
have H : is_closed ((restriction f A) ⁻¹' C),
exact continuous_iff_is_closed.1 HAcont C HCclosed,
have H2 := is_closed_induced_iff.1 H,
cases H2 with D HD,
suffices : f ⁻¹' C ∩ A = D ∩ A,
rw this,
exact is_closed_inter HD.1 HAclosed,
have H₂ : { a : A | a.val ∈ f⁻¹' C} = { a : A | a.val ∈ D},
rw ←preimage_sub X Y f C A,
rw HD.2,
refl,
rw set.inter_comm,
rw set.inter_comm D A,
rwa handy,
end
theorem continuous_closed_union {X Y : Type*} [topological_space X] [topological_space Y] {A B : set X}
(f : X → Y) (Hunion : A ∪ B = set.univ) (HAclosed : is_closed A) (HBclosed : is_closed B) :
continuous (restriction f A) → continuous (restriction f B) → continuous f :=
begin
intros HAcont HBcont,
apply continuous_iff_is_closed.2,
intros C HC,
have H : f⁻¹' C = ((f⁻¹' C) ∩ A) ∪ ((f⁻¹' C) ∩ B),
rw ←set.inter_distrib_left,
rw Hunion,
exact (set.inter_univ _).symm,
rw H,
apply is_closed_union,
exact restriction_closed f A C HAcont HAclosed HC,
exact restriction_closed f B C HBcont HBclosed HC,
end
---- Mario Carneiro (21/07/2018) help
--- Attempt to define function (f : α → β ) in terms of its restriction
-- check two restrictions match
def match_of_fun {X Y} {A B : set X} (fa : A → Y) (fb : B → Y) : Prop :=
∀ x h₁ h₂, fa ⟨x, h₁⟩ = fb ⟨x, h₂⟩
local attribute [instance] classical.prop_decidable
-- define function of pasted restrictions
noncomputable def paste {X Y} {A B : set X} (Hunion : A ∪ B = set.univ)
(fa : A → Y) (fb : B → Y) (t : X) : Y :=
if h₁ : t ∈ A then fa ⟨t, h₁⟩ else
have t ∈ A ∪ B, from set.eq_univ_iff_forall.1 Hunion t,
have h₂ : t ∈ B, from this.resolve_left h₁,
fb ⟨t, h₂⟩
-- check paste agrees with fa
theorem paste_left {X Y} {A B : set X} (Hunion : A ∪ B = set.univ)
(fa : A → Y) (fb : B → Y) (t : X) (h : t ∈ A) :
paste Hunion fa fb t = fa ⟨t, h⟩ := dif_pos _
-- check paste agrees with fb
theorem paste_right {X Y} {A B : set X} (Hunion : A ∪ B = set.univ)
(fa : A → Y) (fb : B → Y) (H : match_of_fun fa fb)
(t : X) (h : t ∈ B) :
paste Hunion fa fb t = fb ⟨t, h⟩ :=
by by_cases h' : t ∈ A; simp [paste, h']; apply H
lemma rest_of_paste {X : Type* } {Y : Type*} {A B : set X} {Hunion : A ∪ B = set.univ} (fa : A → Y) (fb : B → Y)
{ f : X → Y } (H : match_of_fun fa fb) ( Hf : f = paste Hunion fa fb ) :
fa = restriction f A ∧ fb = restriction f B :=
begin split,
funext, unfold restriction, rw Hf,
apply eq.symm _, simp [paste_left Hunion fa fb x.val x.2],
funext, unfold restriction, rw Hf,
apply eq.symm _, simp [paste_right Hunion fa fb H x.val x.2],
end
-- prove continuity when pasted continuous restrictions on closed sets
theorem cont_of_paste₂ {X : Type* } {Y : Type*} [topological_space X] [topological_space Y]
{ A B : set X } { Hunion : A ∪ B = set.univ} {fa : A → Y } { fb : B → Y }
{HAclosed : is_closed A} {HBclosed : is_closed B} { HM: match_of_fun fa fb }
{ f : X → Y } ( Hf : f = paste Hunion fa fb ) :
continuous fa → continuous fb → continuous f :=
begin
intros CA CB,
have ResA : fa = (restriction f A) , exact (rest_of_paste fa fb HM Hf ).1,
have ResB : fb = (restriction f B), exact (rest_of_paste fa fb HM Hf ).2,
rw ResA at CA, rw ResB at CB,
exact continuous_closed_union f Hunion HAclosed HBclosed CA CB
end
theorem cont_of_paste {X : Type* } {Y : Type*} [topological_space X] [topological_space Y]
{ A B : set X } { Hunion : A ∪ B = set.univ} {fa : A → Y } { fb : B → Y }
(HAclosed : is_closed A) (HBclosed : is_closed B) ( HM : match_of_fun fa fb )
( CA : continuous fa ) ( CB : continuous fb) : continuous (paste Hunion fa fb) :=
begin
let f := paste Hunion fa fb,
have Hf : f = paste Hunion fa fb, trivial,
have ResA : fa = (restriction f A) , exact (rest_of_paste fa fb HM Hf ).1,
have ResB : fb = (restriction f B), exact (rest_of_paste fa fb HM Hf ).2,
rw ResA at CA, rwa ResB at CB,
exact continuous_closed_union f Hunion HAclosed HBclosed CA CB
end
|
73796d5885ef66b72ff6782ccc0546fcdbee0c06 | 2eab05920d6eeb06665e1a6df77b3157354316ad | /src/measure_theory/measure/stieltjes.lean | 9cb566b2ffc1870cb5e1ce6dc8d6deb42beff32e | [
"Apache-2.0"
] | permissive | ayush1801/mathlib | 78949b9f789f488148142221606bf15c02b960d2 | ce164e28f262acbb3de6281b3b03660a9f744e3c | refs/heads/master | 1,692,886,907,941 | 1,635,270,866,000 | 1,635,270,866,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 16,782 | lean | /-
Copyright (c) 2021 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Yury Kudryashov, Sébastien Gouëzel
-/
import measure_theory.constructions.borel_space
/-!
# Stieltjes measures on the real line
Consider a function `f : ℝ → ℝ` which is monotone and right-continuous. Then one can define a
corrresponding measure, giving mass `f b - f a` to the interval `(a, b]`.
## Main definitions
* `stieltjes_function` is a structure containing a function from `ℝ → ℝ`, together with the
assertions that it is monotone and right-continuous. To `f : stieltjes_function`, one associates
a Borel measure `f.measure`.
* `f.left_lim x` is the limit of `f` to the left of `x`.
* `f.measure_Ioc` asserts that `f.measure (Ioc a b) = of_real (f b - f a)`
* `f.measure_Ioo` asserts that `f.measure (Ioo a b) = of_real (f.left_lim b - f a)`.
* `f.measure_Icc` and `f.measure_Ico` are analogous.
-/
noncomputable theory
open classical set filter
open ennreal (of_real)
open_locale big_operators ennreal nnreal topological_space
/-! ### Basic properties of Stieltjes functions -/
/-- Bundled monotone right-continuous real functions, used to construct Stieltjes measures. -/
structure stieltjes_function :=
(to_fun : ℝ → ℝ)
(mono' : monotone to_fun)
(right_continuous' : ∀ x, continuous_within_at to_fun (Ici x) x)
namespace stieltjes_function
instance : has_coe_to_fun stieltjes_function (λ _, ℝ → ℝ) := ⟨to_fun⟩
initialize_simps_projections stieltjes_function (to_fun → apply)
variable (f : stieltjes_function)
lemma mono : monotone f := f.mono'
lemma right_continuous (x : ℝ) : continuous_within_at f (Ici x) x := f.right_continuous' x
/-- The limit of a Stieltjes function to the left of `x` (it exists by monotonicity). The fact that
it is indeed a left limit is asserted in `tendsto_left_lim` -/
@[irreducible] def left_lim (x : ℝ) := Sup (f '' (Iio x))
lemma tendsto_left_lim (x : ℝ) : tendsto f (𝓝[Iio x] x) (𝓝 (f.left_lim x)) :=
by { rw left_lim, exact f.mono.tendsto_nhds_within_Iio x }
lemma left_lim_le {x y : ℝ} (h : x ≤ y) : f.left_lim x ≤ f y :=
begin
apply le_of_tendsto (f.tendsto_left_lim x),
filter_upwards [self_mem_nhds_within],
assume z hz,
exact (f.mono (le_of_lt hz)).trans (f.mono h)
end
lemma le_left_lim {x y : ℝ} (h : x < y) : f x ≤ f.left_lim y :=
begin
apply ge_of_tendsto (f.tendsto_left_lim y),
apply mem_nhds_within_Iio_iff_exists_Ioo_subset.2 ⟨x, h, _⟩,
assume z hz,
exact f.mono hz.1.le,
end
lemma left_lim_le_left_lim {x y : ℝ} (h : x ≤ y) : f.left_lim x ≤ f.left_lim y :=
begin
rcases eq_or_lt_of_le h with rfl|hxy,
{ exact le_rfl },
{ exact (f.left_lim_le le_rfl).trans (f.le_left_lim hxy) }
end
/-- The identity of `ℝ` as a Stieltjes function, used to construct Lebesgue measure. -/
@[simps] protected def id : stieltjes_function :=
{ to_fun := id,
mono' := λ x y, id,
right_continuous' := λ x, continuous_within_at_id }
@[simp] lemma id_left_lim (x : ℝ) : stieltjes_function.id.left_lim x = x :=
tendsto_nhds_unique (stieltjes_function.id.tendsto_left_lim x) $
(continuous_at_id).tendsto.mono_left nhds_within_le_nhds
instance : inhabited stieltjes_function := ⟨stieltjes_function.id⟩
/-! ### The outer measure associated to a Stieltjes function -/
/-- Length of an interval. This is the largest monotone function which correctly measures all
intervals. -/
def length (s : set ℝ) : ℝ≥0∞ := ⨅a b (h : s ⊆ Ioc a b), of_real (f b - f a)
@[simp] lemma length_empty : f.length ∅ = 0 :=
nonpos_iff_eq_zero.1 $ infi_le_of_le 0 $ infi_le_of_le 0 $ by simp
@[simp] lemma length_Ioc (a b : ℝ) :
f.length (Ioc a b) = of_real (f b - f a) :=
begin
refine le_antisymm (infi_le_of_le a $ binfi_le b (subset.refl _))
(le_infi $ λ a', le_infi $ λ b', le_infi $ λ h, ennreal.coe_le_coe.2 _),
cases le_or_lt b a with ab ab,
{ rw real.to_nnreal_of_nonpos (sub_nonpos.2 (f.mono ab)), apply zero_le, },
cases (Ioc_subset_Ioc_iff ab).1 h with h₁ h₂,
exact real.to_nnreal_le_to_nnreal (sub_le_sub (f.mono h₁) (f.mono h₂))
end
lemma length_mono {s₁ s₂ : set ℝ} (h : s₁ ⊆ s₂) :
f.length s₁ ≤ f.length s₂ :=
infi_le_infi $ λ a, infi_le_infi $ λ b, infi_le_infi2 $ λ h', ⟨subset.trans h h', le_refl _⟩
open measure_theory
/-- The Stieltjes outer measure associated to a Stieltjes function. -/
protected def outer : outer_measure ℝ :=
outer_measure.of_function f.length f.length_empty
lemma outer_le_length (s : set ℝ) : f.outer s ≤ f.length s :=
outer_measure.of_function_le _
/-- If a compact interval `[a, b]` is covered by a union of open interval `(c i, d i)`, then
`f b - f a ≤ ∑ f (d i) - f (c i)`. This is an auxiliary technical statement to prove the same
statement for half-open intervals, the point of the current statement being that one can use
compactness to reduce it to a finite sum, and argue by induction on the size of the covering set. -/
lemma length_subadditive_Icc_Ioo {a b : ℝ} {c d : ℕ → ℝ}
(ss : Icc a b ⊆ ⋃ i, Ioo (c i) (d i)) :
of_real (f b - f a) ≤ ∑' i, of_real (f (d i) - f (c i)) :=
begin
suffices : ∀ (s:finset ℕ) b
(cv : Icc a b ⊆ ⋃ i ∈ (↑s:set ℕ), Ioo (c i) (d i)),
(of_real (f b - f a) : ℝ≥0∞) ≤ ∑ i in s, of_real (f (d i) - f (c i)),
{ rcases is_compact_Icc.elim_finite_subcover_image (λ (i : ℕ) (_ : i ∈ univ),
@is_open_Ioo _ _ _ _ (c i) (d i)) (by simpa using ss) with ⟨s, su, hf, hs⟩,
have e : (⋃ i ∈ (↑hf.to_finset:set ℕ), Ioo (c i) (d i)) = (⋃ i ∈ s, Ioo (c i) (d i)),
by simp only [ext_iff, exists_prop, finset.set_bUnion_coe, mem_Union, forall_const, iff_self,
finite.mem_to_finset],
rw ennreal.tsum_eq_supr_sum,
refine le_trans _ (le_supr _ hf.to_finset),
exact this hf.to_finset _ (by simpa only [e]) },
clear ss b,
refine λ s, finset.strong_induction_on s (λ s IH b cv, _),
cases le_total b a with ab ab,
{ rw ennreal.of_real_eq_zero.2 (sub_nonpos.2 (f.mono ab)), exact zero_le _, },
have := cv ⟨ab, le_refl _⟩, simp at this,
rcases this with ⟨i, is, cb, bd⟩,
rw [← finset.insert_erase is] at cv ⊢,
rw [finset.coe_insert, bUnion_insert] at cv,
rw [finset.sum_insert (finset.not_mem_erase _ _)],
refine le_trans _ (add_le_add_left (IH _ (finset.erase_ssubset is) (c i) _) _),
{ refine le_trans (ennreal.of_real_le_of_real _) ennreal.of_real_add_le,
rw sub_add_sub_cancel,
exact sub_le_sub_right (f.mono bd.le) _ },
{ rintro x ⟨h₁, h₂⟩,
refine (cv ⟨h₁, le_trans h₂ (le_of_lt cb)⟩).resolve_left
(mt and.left (not_lt_of_le h₂)) }
end
@[simp] lemma outer_Ioc (a b : ℝ) :
f.outer (Ioc a b) = of_real (f b - f a) :=
begin
/- It suffices to show that, if `(a, b]` is covered by sets `s i`, then `f b - f a` is bounded
by `∑ f.length (s i) + ε`. The difficulty is that `f.length` is expressed in terms of half-open
intervals, while we would like to have a compact interval covered by open intervals to use
compactness and finite sums, as provided by `length_subadditive_Icc_Ioo`. The trick is to use the
right-continuity of `f`. If `a'` is close enough to `a` on its right, then `[a', b]` is still
covered by the sets `s i` and moreover `f b - f a'` is very close to `f b - f a` (up to `ε/2`).
Also, by definition one can cover `s i` by a half-closed interval `(p i, q i]` with `f`-length
very close to that of `s i` (within a suitably small `ε' i`, say). If one moves `q i` very
slightly to the right, then the `f`-length will change very little by right continuity, and we
will get an open interval `(p i, q' i)` covering `s i` with `f (q' i) - f (p i)` within `ε' i`
of the `f`-length of `s i`. -/
refine le_antisymm (by { rw ← f.length_Ioc, apply outer_le_length })
(le_binfi $ λ s hs, ennreal.le_of_forall_pos_le_add $ λ ε εpos h, _),
let δ := ε / 2,
have δpos : 0 < (δ : ℝ≥0∞), by simpa using εpos.ne',
rcases ennreal.exists_pos_sum_of_encodable δpos.ne' ℕ with ⟨ε', ε'0, hε⟩,
obtain ⟨a', ha', aa'⟩ : ∃ a', f a' - f a < δ ∧ a < a',
{ have A : continuous_within_at (λ r, f r - f a) (Ioi a) a,
{ refine continuous_within_at.sub _ continuous_within_at_const,
exact (f.right_continuous a).mono Ioi_subset_Ici_self },
have B : f a - f a < δ, by rwa [sub_self, nnreal.coe_pos, ← ennreal.coe_pos],
exact (((tendsto_order.1 A).2 _ B).and self_mem_nhds_within).exists },
have : ∀ i, ∃ p:ℝ×ℝ, s i ⊆ Ioo p.1 p.2 ∧
(of_real (f p.2 - f p.1) : ℝ≥0∞) < f.length (s i) + ε' i,
{ intro i,
have := (ennreal.lt_add_right ((ennreal.le_tsum i).trans_lt h).ne
(ennreal.coe_ne_zero.2 (ε'0 i).ne')),
conv at this { to_lhs, rw length },
simp only [infi_lt_iff, exists_prop] at this,
rcases this with ⟨p, q', spq, hq'⟩,
have : continuous_within_at (λ r, of_real (f r - f p)) (Ioi q') q',
{ apply ennreal.continuous_of_real.continuous_at.comp_continuous_within_at,
refine continuous_within_at.sub _ continuous_within_at_const,
exact (f.right_continuous q').mono Ioi_subset_Ici_self },
rcases (((tendsto_order.1 this).2 _ hq').and self_mem_nhds_within).exists with ⟨q, hq, q'q⟩,
exact ⟨⟨p, q⟩, spq.trans (Ioc_subset_Ioo_right q'q), hq⟩ },
choose g hg using this,
have I_subset : Icc a' b ⊆ ⋃ i, Ioo (g i).1 (g i).2 := calc
Icc a' b ⊆ Ioc a b : λ x hx, ⟨aa'.trans_le hx.1, hx.2⟩
... ⊆ ⋃ i, s i : hs
... ⊆ ⋃ i, Ioo (g i).1 (g i).2 : Union_subset_Union (λ i, (hg i).1),
calc of_real (f b - f a)
= of_real ((f b - f a') + (f a' - f a)) : by rw sub_add_sub_cancel
... ≤ of_real (f b - f a') + of_real (f a' - f a) : ennreal.of_real_add_le
... ≤ (∑' i, of_real (f (g i).2 - f (g i).1)) + of_real δ :
add_le_add (f.length_subadditive_Icc_Ioo I_subset) (ennreal.of_real_le_of_real ha'.le)
... ≤ (∑' i, (f.length (s i) + ε' i)) + δ :
add_le_add (ennreal.tsum_le_tsum (λ i, (hg i).2.le))
(by simp only [ennreal.of_real_coe_nnreal, le_rfl])
... = (∑' i, f.length (s i)) + (∑' i, ε' i) + δ : by rw [ennreal.tsum_add]
... ≤ (∑' i, f.length (s i)) + δ + δ : add_le_add (add_le_add le_rfl hε.le) le_rfl
... = ∑' (i : ℕ), f.length (s i) + ε : by simp [add_assoc, ennreal.add_halves]
end
lemma measurable_set_Ioi {c : ℝ} :
f.outer.caratheodory.measurable_set' (Ioi c) :=
begin
apply outer_measure.of_function_caratheodory (λ t, _),
refine le_infi (λ a, le_infi (λ b, le_infi (λ h, _))),
refine le_trans (add_le_add
(f.length_mono $ inter_subset_inter_left _ h)
(f.length_mono $ diff_subset_diff_left h)) _,
cases le_total a c with hac hac; cases le_total b c with hbc hbc,
{ simp only [Ioc_inter_Ioi, f.length_Ioc, hac, sup_eq_max, hbc, le_refl, Ioc_eq_empty,
max_eq_right, min_eq_left, Ioc_diff_Ioi, f.length_empty, zero_add, not_lt] },
{ simp only [hac, hbc, Ioc_inter_Ioi, Ioc_diff_Ioi, f.length_Ioc, min_eq_right,
sup_eq_max, ←ennreal.of_real_add, f.mono hac, f.mono hbc, sub_nonneg, sub_add_sub_cancel,
le_refl, max_eq_right] },
{ simp only [hbc, le_refl, Ioc_eq_empty, Ioc_inter_Ioi, min_eq_left, Ioc_diff_Ioi,
f.length_empty, zero_add, or_true, le_sup_iff, f.length_Ioc, not_lt] },
{ simp only [hac, hbc, Ioc_inter_Ioi, Ioc_diff_Ioi, f.length_Ioc, min_eq_right,
sup_eq_max, le_refl, Ioc_eq_empty, add_zero, max_eq_left, f.length_empty, not_lt] }
end
theorem outer_trim : f.outer.trim = f.outer :=
begin
refine le_antisymm (λ s, _) (outer_measure.le_trim _),
rw outer_measure.trim_eq_infi,
refine le_infi (λ t, le_infi $ λ ht,
ennreal.le_of_forall_pos_le_add $ λ ε ε0 h, _),
rcases ennreal.exists_pos_sum_of_encodable
(ennreal.coe_pos.2 ε0).ne' ℕ with ⟨ε', ε'0, hε⟩,
refine le_trans _ (add_le_add_left (le_of_lt hε) _),
rw ← ennreal.tsum_add,
choose g hg using show
∀ i, ∃ s, t i ⊆ s ∧ measurable_set s ∧
f.outer s ≤ f.length (t i) + of_real (ε' i),
{ intro i,
have := (ennreal.lt_add_right ((ennreal.le_tsum i).trans_lt h).ne
(ennreal.coe_pos.2 (ε'0 i)).ne'),
conv at this {to_lhs, rw length},
simp only [infi_lt_iff] at this,
rcases this with ⟨a, b, h₁, h₂⟩,
rw ← f.outer_Ioc at h₂,
exact ⟨_, h₁, measurable_set_Ioc, le_of_lt $ by simpa using h₂⟩ },
simp at hg,
apply infi_le_of_le (Union g) _,
apply infi_le_of_le (subset.trans ht $ Union_subset_Union (λ i, (hg i).1)) _,
apply infi_le_of_le (measurable_set.Union (λ i, (hg i).2.1)) _,
exact le_trans (f.outer.Union _) (ennreal.tsum_le_tsum $ λ i, (hg i).2.2)
end
lemma borel_le_measurable : borel ℝ ≤ f.outer.caratheodory :=
begin
rw borel_eq_generate_Ioi,
refine measurable_space.generate_from_le _,
simp [f.measurable_set_Ioi] { contextual := tt }
end
/-! ### The measure associated to a Stieltjes function -/
/-- The measure associated to a Stieltjes function, giving mass `f b - f a` to the
interval `(a, b]`. -/
@[irreducible] protected def measure : measure ℝ :=
{ to_outer_measure := f.outer,
m_Union := λ s hs, f.outer.Union_eq_of_caratheodory $
λ i, f.borel_le_measurable _ (hs i),
trimmed := f.outer_trim }
@[simp] lemma measure_Ioc (a b : ℝ) : f.measure (Ioc a b) = of_real (f b - f a) :=
by { rw stieltjes_function.measure, exact f.outer_Ioc a b }
@[simp] lemma measure_singleton (a : ℝ) : f.measure {a} = of_real (f a - f.left_lim a) :=
begin
obtain ⟨u, u_mono, u_lt_a, u_lim⟩ : ∃ (u : ℕ → ℝ), strict_mono u ∧ (∀ (n : ℕ), u n < a)
∧ tendsto u at_top (𝓝 a) := exists_seq_strict_mono_tendsto a,
have A : {a} = ⋂ n, Ioc (u n) a,
{ refine subset.antisymm (λ x hx, by simp [mem_singleton_iff.1 hx, u_lt_a]) (λ x hx, _),
simp at hx,
have : a ≤ x := le_of_tendsto' u_lim (λ n, (hx n).1.le),
simp [le_antisymm this (hx 0).2] },
have L1 : tendsto (λ n, f.measure (Ioc (u n) a)) at_top (𝓝 (f.measure {a})),
{ rw A,
refine tendsto_measure_Inter (λ n, measurable_set_Ioc) (λ m n hmn, _) _,
{ exact Ioc_subset_Ioc (u_mono.monotone hmn) le_rfl },
{ exact ⟨0, by simpa only [measure_Ioc] using ennreal.of_real_ne_top⟩ } },
have L2 : tendsto (λ n, f.measure (Ioc (u n) a)) at_top (𝓝 (of_real (f a - f.left_lim a))),
{ simp only [measure_Ioc],
have : tendsto (λ n, f (u n)) at_top (𝓝 (f.left_lim a)),
{ apply (f.tendsto_left_lim a).comp,
exact tendsto_nhds_within_of_tendsto_nhds_of_eventually_within _ u_lim
(eventually_of_forall (λ n, u_lt_a n)) },
exact ennreal.continuous_of_real.continuous_at.tendsto.comp (tendsto_const_nhds.sub this) },
exact tendsto_nhds_unique L1 L2
end
@[simp] lemma measure_Icc (a b : ℝ) : f.measure (Icc a b) = of_real (f b - f.left_lim a) :=
begin
rcases le_or_lt a b with hab|hab,
{ have A : disjoint {a} (Ioc a b), by simp,
simp [← Icc_union_Ioc_eq_Icc le_rfl hab, -singleton_union, ← ennreal.of_real_add, f.left_lim_le,
measure_union A (measurable_set_singleton a) measurable_set_Ioc, f.mono hab] },
{ simp only [hab, measure_empty, Icc_eq_empty, not_le],
symmetry,
simp [ennreal.of_real_eq_zero, f.le_left_lim hab] }
end
@[simp] lemma measure_Ioo {a b : ℝ} : f.measure (Ioo a b) = of_real (f.left_lim b - f a) :=
begin
rcases le_or_lt b a with hab|hab,
{ simp only [hab, measure_empty, Ioo_eq_empty, not_lt],
symmetry,
simp [ennreal.of_real_eq_zero, f.left_lim_le hab] },
{ have A : disjoint (Ioo a b) {b}, by simp,
have D : f b - f a = (f b - f.left_lim b) + (f.left_lim b - f a), by abel,
have := f.measure_Ioc a b,
simp only [←Ioo_union_Icc_eq_Ioc hab le_rfl, measure_singleton,
measure_union A measurable_set_Ioo (measurable_set_singleton b), Icc_self] at this,
rw [D, ennreal.of_real_add, add_comm] at this,
{ simpa only [ennreal.add_right_inj ennreal.of_real_ne_top] },
{ simp only [f.left_lim_le, sub_nonneg] },
{ simp only [f.le_left_lim hab, sub_nonneg] } },
end
@[simp] lemma measure_Ico (a b : ℝ) : f.measure (Ico a b) = of_real (f.left_lim b - f.left_lim a) :=
begin
rcases le_or_lt b a with hab|hab,
{ simp only [hab, measure_empty, Ico_eq_empty, not_lt],
symmetry,
simp [ennreal.of_real_eq_zero, f.left_lim_le_left_lim hab] },
{ have A : disjoint {a} (Ioo a b) := by simp,
simp [← Icc_union_Ioo_eq_Ico le_rfl hab, -singleton_union, hab.ne, f.left_lim_le,
measure_union A (measurable_set_singleton a) measurable_set_Ioo, f.le_left_lim hab,
← ennreal.of_real_add] }
end
end stieltjes_function
|
cad48983d7606852dd770420680cb125e3caea62 | bbecf0f1968d1fba4124103e4f6b55251d08e9c4 | /src/algebra/free.lean | 245761a39b2e470fc73a1dff206217f31441eb20 | [
"Apache-2.0"
] | permissive | waynemunro/mathlib | e3fd4ff49f4cb43d4a8ded59d17be407bc5ee552 | 065a70810b5480d584033f7bbf8e0409480c2118 | refs/heads/master | 1,693,417,182,397 | 1,634,644,781,000 | 1,634,644,781,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 23,093 | lean | /-
Copyright (c) 2019 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau
-/
import data.equiv.basic
import control.applicative
import control.traversable.basic
import algebra.group.hom
/-!
# Free constructions
## Main definitions
* `free_magma α`: free magma (structure with binary operation without any axioms) over alphabet `α`,
defined inductively, with traversable instance and decidable equality.
* `magma.free_semigroup α`: free semigroup over magma `α`.
* `free_semigroup α`: free semigroup over alphabet `α`, defined as a synonym for `α × list α`
(i.e. nonempty lists), with traversable instance and decidable equality.
* `free_semigroup_free_magma α`: isomorphism between `magma.free_semigroup (free_magma α)` and
`free_semigroup α`.
* `free_magma.lift`: the universal property of the free magma, expressing its adjointness.
-/
universes u v l
/-- Free magma over a given alphabet. -/
@[derive decidable_eq]
inductive free_magma (α : Type u) : Type u
| of : α → free_magma
| mul : free_magma → free_magma → free_magma
/-- Free nonabelian additive magma over a given alphabet. -/
@[derive decidable_eq]
inductive free_add_magma (α : Type u) : Type u
| of : α → free_add_magma
| add : free_add_magma → free_add_magma → free_add_magma
attribute [to_additive] free_magma
namespace free_magma
variables {α : Type u}
@[to_additive]
instance [inhabited α] : inhabited (free_magma α) := ⟨of (default _)⟩
@[to_additive]
instance : has_mul (free_magma α) := ⟨free_magma.mul⟩
attribute [pattern] has_mul.mul
@[simp, to_additive]
theorem mul_eq (x y : free_magma α) : mul x y = x * y := rfl
/-- Recursor for `free_magma` using `x * y` instead of `free_magma.mul x y`. -/
@[elab_as_eliminator, to_additive
"Recursor for `free_add_magma` using `x + y` instead of `free_add_magma.add x y`."]
def rec_on' {C : free_magma α → Sort l} (x)
(ih1 : ∀ x, C (of x)) (ih2 : ∀ x y, C x → C y → C (x * y)) :
C x :=
free_magma.rec_on x ih1 ih2
end free_magma
/-- Lifts a function `α → β` to a magma homomorphism `free_magma α → β` given a magma `β`. -/
def free_magma.lift_aux {α : Type u} {β : Type v} [has_mul β] (f : α → β) : free_magma α → β
| (free_magma.of x) := f x
| (x * y) := x.lift_aux * y.lift_aux
/-- Lifts a function `α → β` to an additive magma homomorphism `free_add_magma α → β` given
an additive magma `β`. -/
def free_add_magma.lift_aux {α : Type u} {β : Type v} [has_add β] (f : α → β) : free_add_magma α → β
| (free_add_magma.of x) := f x
| (x + y) := x.lift_aux + y.lift_aux
attribute [to_additive free_add_magma.lift_aux] free_magma.lift_aux
namespace free_magma
variables {α : Type u} {β : Type v} [has_mul β] (f : α → β)
@[to_additive]
theorem lift_aux_unique (F : mul_hom (free_magma α) β) : ⇑F = lift_aux (F ∘ of) :=
funext $ λ x, free_magma.rec_on x (λ x, rfl) $ λ x y ih1 ih2,
(F.map_mul x y).trans $ congr (congr_arg _ ih1) ih2
/-- The universal property of the free magma expressing its adjointness. -/
@[to_additive "The universal property of the free additive magma expressing its adjointness."]
def lift : (α → β) ≃ mul_hom (free_magma α) β :=
{ to_fun := λ f,
{ to_fun := lift_aux f,
map_mul' := λ x y, rfl, },
inv_fun := λ F, F ∘ of,
left_inv := λ f, by { ext, simp only [lift_aux, mul_hom.coe_mk, function.comp_app], },
right_inv := λ F, by { ext, rw [mul_hom.coe_mk, lift_aux_unique], } }
@[simp, to_additive] lemma lift_of (x) : lift f (of x) = f x := rfl
end free_magma
/-- The unique magma homomorphism `free_magma α → free_magma β` that sends
each `of x` to `of (f x)`. -/
def free_magma.map {α : Type u} {β : Type v} (f : α → β) : free_magma α → free_magma β
| (free_magma.of x) := free_magma.of (f x)
| (x * y) := x.map * y.map
/-- The unique additive magma homomorphism `free_add_magma α → free_add_magma β` that sends
each `of x` to `of (f x)`. -/
def free_add_magma.map {α : Type u} {β : Type v} (f : α → β) : free_add_magma α → free_add_magma β
| (free_add_magma.of x) := free_add_magma.of (f x)
| (x + y) := x.map + y.map
attribute [to_additive free_add_magma.map] free_magma.map
namespace free_magma
variables {α : Type u}
section map
variables {β : Type v} (f : α → β)
@[simp, to_additive] lemma map_of (x) : map f (of x) = of (f x) := rfl
@[simp, to_additive] lemma map_mul (x y) : map f (x * y) = map f x * map f y := rfl
end map
section category
@[to_additive]
instance : monad free_magma :=
{ pure := λ _, of,
bind := λ _ _ x f, lift f x }
/-- Recursor on `free_magma` using `pure` instead of `of`. -/
@[elab_as_eliminator, to_additive "Recursor on `free_add_magma` using `pure` instead of `of`."]
protected def rec_on'' {C : free_magma α → Sort l} (x)
(ih1 : ∀ x, C (pure x)) (ih2 : ∀ x y, C x → C y → C (x * y)) :
C x :=
free_magma.rec_on' x ih1 ih2
variables {β : Type u}
@[simp, to_additive]
lemma map_pure (f : α → β) (x) : (f <$> pure x : free_magma β) = pure (f x) := rfl
@[simp, to_additive]
lemma map_mul' (f : α → β) (x y : free_magma α) : (f <$> (x * y)) = (f <$> x * f <$> y) := rfl
@[simp, to_additive]
lemma pure_bind (f : α → free_magma β) (x) : (pure x >>= f) = f x := rfl
@[simp, to_additive]
lemma mul_bind (f : α → free_magma β) (x y : free_magma α) :
(x * y >>= f) = ((x >>= f) * (y >>= f)) := rfl
@[simp, to_additive]
lemma pure_seq {α β : Type u} {f : α → β} {x : free_magma α} : pure f <*> x = f <$> x := rfl
@[simp, to_additive]
lemma mul_seq {α β : Type u} {f g : free_magma (α → β)} {x : free_magma α} :
(f * g) <*> x = (f <*> x) * (g <*> x) := rfl
@[to_additive]
instance : is_lawful_monad free_magma.{u} :=
{ pure_bind := λ _ _ _ _, rfl,
bind_assoc := λ α β γ x f g, free_magma.rec_on'' x (λ x, rfl)
(λ x y ih1 ih2, by rw [mul_bind, mul_bind, mul_bind, ih1, ih2]),
id_map := λ α x, free_magma.rec_on'' x (λ _, rfl)
(λ x y ih1 ih2, by rw [map_mul', ih1, ih2]) }
end category
end free_magma
/-- `free_magma` is traversable. -/
protected def free_magma.traverse {m : Type u → Type u} [applicative m] {α β : Type u}
(F : α → m β) :
free_magma α → m (free_magma β)
| (free_magma.of x) := free_magma.of <$> F x
| (x * y) := (*) <$> x.traverse <*> y.traverse
/-- `free_add_magma` is traversable. -/
protected def free_add_magma.traverse {m : Type u → Type u} [applicative m] {α β : Type u}
(F : α → m β) :
free_add_magma α → m (free_add_magma β)
| (free_add_magma.of x) := free_add_magma.of <$> F x
| (x + y) := (+) <$> x.traverse <*> y.traverse
attribute [to_additive free_add_magma.traverse] free_magma.traverse
namespace free_magma
variables {α : Type u}
section category
variables {β : Type u}
@[to_additive]
instance : traversable free_magma := ⟨@free_magma.traverse⟩
variables {m : Type u → Type u} [applicative m] (F : α → m β)
@[simp, to_additive]
lemma traverse_pure (x) : traverse F (pure x : free_magma α) = pure <$> F x := rfl
@[simp, to_additive]
lemma traverse_pure' : traverse F ∘ pure = λ x, (pure <$> F x : m (free_magma β)) := rfl
@[simp, to_additive]
lemma traverse_mul (x y : free_magma α) :
traverse F (x * y) = (*) <$> traverse F x <*> traverse F y := rfl
@[simp, to_additive]
lemma traverse_mul' :
function.comp (traverse F) ∘ @has_mul.mul (free_magma α) _ =
λ x y, (*) <$> traverse F x <*> traverse F y := rfl
@[simp, to_additive]
lemma traverse_eq (x) : free_magma.traverse F x = traverse F x := rfl
@[simp, to_additive]
lemma mul_map_seq (x y : free_magma α) :
((*) <$> x <*> y : id (free_magma α)) = (x * y : free_magma α) := rfl
@[to_additive]
instance : is_lawful_traversable free_magma.{u} :=
{ id_traverse := λ α x, free_magma.rec_on'' x (λ x, rfl)
(λ x y ih1 ih2, by rw [traverse_mul, ih1, ih2, mul_map_seq]),
comp_traverse := λ F G hf1 hg1 hf2 hg2 α β γ f g x, free_magma.rec_on'' x
(λ x, by resetI; simp only [traverse_pure, traverse_pure'] with functor_norm)
(λ x y ih1 ih2, by resetI; rw [traverse_mul, ih1, ih2, traverse_mul];
simp only [traverse_mul'] with functor_norm),
naturality := λ F G hf1 hg1 hf2 hg2 η α β f x, free_magma.rec_on'' x
(λ x, by simp only [traverse_pure] with functor_norm)
(λ x y ih1 ih2, by simp only [traverse_mul] with functor_norm; rw [ih1, ih2]),
traverse_eq_map_id := λ α β f x, free_magma.rec_on'' x (λ _, rfl)
(λ x y ih1 ih2, by rw [traverse_mul, ih1, ih2, map_mul', mul_map_seq]; refl),
.. free_magma.is_lawful_monad }
end category
end free_magma
/-- Representation of an element of a free magma. -/
protected def free_magma.repr {α : Type u} [has_repr α] : free_magma α → string
| (free_magma.of x) := repr x
| (x * y) := "( " ++ x.repr ++ " * " ++ y.repr ++ " )"
/-- Representation of an element of a free additive magma. -/
protected def free_add_magma.repr {α : Type u} [has_repr α] : free_add_magma α → string
| (free_add_magma.of x) := repr x
| (x + y) := "( " ++ x.repr ++ " + " ++ y.repr ++ " )"
attribute [to_additive free_add_magma.repr] free_magma.repr
@[to_additive]
instance {α : Type u} [has_repr α] : has_repr (free_magma α) := ⟨free_magma.repr⟩
/-- Length of an element of a free magma. -/
def free_magma.length {α : Type u} : free_magma α → ℕ
| (free_magma.of x) := 1
| (x * y) := x.length + y.length
/-- Length of an element of a free additive magma. -/
def free_add_magma.length {α : Type u} : free_add_magma α → ℕ
| (free_add_magma.of x) := 1
| (x + y) := x.length + y.length
attribute [to_additive free_add_magma.length] free_magma.length
/-- Associativity relations for a magma. -/
inductive magma.free_semigroup.r (α : Type u) [has_mul α] : α → α → Prop
| intro : ∀ x y z, magma.free_semigroup.r ((x * y) * z) (x * (y * z))
| left : ∀ w x y z, magma.free_semigroup.r (w * ((x * y) * z)) (w * (x * (y * z)))
/-- Associativity relations for an additive magma. -/
inductive add_magma.free_add_semigroup.r (α : Type u) [has_add α] : α → α → Prop
| intro : ∀ x y z, add_magma.free_add_semigroup.r ((x + y) + z) (x + (y + z))
| left : ∀ w x y z, add_magma.free_add_semigroup.r (w + ((x + y) + z)) (w + (x + (y + z)))
attribute [to_additive add_magma.free_add_semigroup.r] magma.free_semigroup.r
namespace magma
/-- Free semigroup over a magma. -/
@[to_additive add_magma.free_add_semigroup "Free additive semigroup over an additive magma."]
def free_semigroup (α : Type u) [has_mul α] : Type u :=
quot $ free_semigroup.r α
namespace free_semigroup
variables {α : Type u} [has_mul α]
/-- Embedding from magma to its free semigroup. -/
@[to_additive "Embedding from additive magma to its free additive semigroup."]
def of : α → free_semigroup α := quot.mk _
@[to_additive]
instance [inhabited α] : inhabited (free_semigroup α) := ⟨of (default _)⟩
@[elab_as_eliminator, to_additive]
protected lemma induction_on {C : free_semigroup α → Prop} (x : free_semigroup α)
(ih : ∀ x, C (of x)) : C x :=
quot.induction_on x ih
@[to_additive]
theorem of_mul_assoc (x y z : α) : of ((x * y) * z) = of (x * (y * z)) :=
quot.sound $ r.intro x y z
@[to_additive]
theorem of_mul_assoc_left (w x y z : α) : of (w * ((x * y) * z)) = of (w * (x * (y * z))) :=
quot.sound $ r.left w x y z
@[to_additive]
theorem of_mul_assoc_right (w x y z : α) : of (((w * x) * y) * z) = of ((w * (x * y)) * z) :=
by rw [of_mul_assoc, of_mul_assoc, of_mul_assoc, of_mul_assoc_left]
@[to_additive]
instance : semigroup (free_semigroup α) :=
{ mul := λ x y, begin
refine quot.lift_on x (λ p, quot.lift_on y (λ q, (quot.mk _ $ p * q : free_semigroup α)) _) _,
{ rintros a b (⟨c, d, e⟩ | ⟨c, d, e, f⟩); change of _ = of _,
{ rw of_mul_assoc_left },
{ rw [← of_mul_assoc, of_mul_assoc_left, of_mul_assoc] } },
{ refine quot.induction_on y (λ q, _),
rintros a b (⟨c, d, e⟩ | ⟨c, d, e, f⟩); change of _ = of _,
{ rw of_mul_assoc_right },
{ rw [of_mul_assoc, of_mul_assoc, of_mul_assoc_left, of_mul_assoc_left, of_mul_assoc_left,
← of_mul_assoc c d, ← of_mul_assoc c d, of_mul_assoc_left] } }
end,
mul_assoc := λ x y z, quot.induction_on x $ λ p, quot.induction_on y $ λ q,
quot.induction_on z $ λ r, of_mul_assoc p q r }
@[to_additive]
theorem of_mul (x y : α) : of (x * y) = of x * of y := rfl
section lift
variables {β : Type v} [semigroup β] (f : α → β)
/-- Lifts a magma homomorphism `α → β` to a semigroup homomorphism `magma.free_semigroup α → β`
given a semigroup `β`. -/
@[to_additive "Lifts an additive magma homomorphism `α → β` to an additive semigroup homomorphism
`add_magma.free_add_semigroup α → β` given an additive semigroup `β`."]
def lift (hf : ∀ x y, f (x * y) = f x * f y) : free_semigroup α → β :=
quot.lift f $ by rintros a b (⟨c, d, e⟩ | ⟨c, d, e, f⟩); simp only [hf, mul_assoc]
@[simp, to_additive] lemma lift_of {hf} (x : α) : lift f hf (of x) = f x := rfl
@[simp, to_additive] lemma lift_mul {hf} (x y) : lift f hf (x * y) = lift f hf x * lift f hf y :=
quot.induction_on x $ λ p, quot.induction_on y $ λ q, hf p q
@[to_additive]
theorem lift_unique (f : free_semigroup α → β) (hf : ∀ x y, f (x * y) = f x * f y) :
f = lift (f ∘ of) (λ p q, hf (of p) (of q)) :=
funext $ λ x, quot.induction_on x $ λ p, rfl
end lift
variables {β : Type v} [has_mul β] (f : α → β)
/-- From a magma homomorphism `α → β` to a semigroup homomorphism
`magma.free_semigroup α → magma.free_semigroup β`. -/
@[to_additive "From an additive magma homomorphism `α → β` to an additive semigroup homomorphism
`add_magma.free_add_semigroup α → add_magma.free_add_semigroup β`."]
def map (hf : ∀ x y, f (x * y) = f x * f y) : free_semigroup α → free_semigroup β :=
lift (of ∘ f) (λ x y, congr_arg of $ hf x y)
@[simp, to_additive] lemma map_of {hf} (x) : map f hf (of x) = of (f x) := rfl
@[simp, to_additive] lemma map_mul {hf} (x y) : map f hf (x * y) = map f hf x * map f hf y :=
lift_mul _ _ _
end free_semigroup
end magma
/-- Free semigroup over a given alphabet.
(Note: In this definition, the free semigroup does not contain the empty word.) -/
@[to_additive "Free additive semigroup over a given alphabet."]
def free_semigroup (α : Type u) : Type u :=
α × list α
namespace free_semigroup
variables {α : Type u}
@[to_additive]
instance : semigroup (free_semigroup α) :=
{ mul := λ L1 L2, (L1.1, L1.2 ++ L2.1 :: L2.2),
mul_assoc := λ L1 L2 L3, prod.ext rfl $ list.append_assoc _ _ _ }
/-- The embedding `α → free_semigroup α`. -/
@[to_additive "The embedding `α → free_add_semigroup α`."]
def of (x : α) : free_semigroup α :=
(x, [])
@[to_additive]
instance [inhabited α] : inhabited (free_semigroup α) := ⟨of (default _)⟩
/-- Recursor for free semigroup using `of` and `*`. -/
@[elab_as_eliminator, to_additive "Recursor for free additive semigroup using `of` and `+`."]
protected def rec_on {C : free_semigroup α → Sort l} (x)
(ih1 : ∀ x, C (of x)) (ih2 : ∀ x y, C (of x) → C y → C (of x * y)) :
C x :=
prod.rec_on x $ λ f s, list.rec_on s ih1 (λ hd tl ih f, ih2 f (hd, tl) (ih1 f) (ih hd)) f
end free_semigroup
/-- Auxiliary function for `free_semigroup.lift`. -/
def free_semigroup.lift' {α : Type u} {β : Type v} [semigroup β] (f : α → β) : α → list α → β
| x [] := f x
| x (hd::tl) := f x * free_semigroup.lift' hd tl
/-- Auxiliary function for `free_semigroup.lift`. -/
def free_add_semigroup.lift' {α : Type u} {β : Type v} [add_semigroup β] (f : α → β) :
α → list α → β
| x [] := f x
| x (hd::tl) := f x + free_add_semigroup.lift' hd tl
attribute [to_additive free_add_semigroup.lift'] free_semigroup.lift'
namespace free_semigroup
variables {α : Type u}
section lift
variables {β : Type v} [semigroup β] (f : α → β)
/-- Lifts a function `α → β` to a semigroup homomorphism `free_semigroup α → β` given
a semigroup `β`. -/
@[to_additive "Lifts a function `α → β` to an additive semigroup homomorphism
`free_add_semigroup α → β` given an additive semigroup `β`."]
def lift (x : free_semigroup α) : β :=
lift' f x.1 x.2
@[simp, to_additive] lemma lift_of (x : α) : lift f (of x) = f x := rfl
@[to_additive] lemma lift_of_mul (x y) : lift f (of x * y) = f x * lift f y := rfl
@[simp, to_additive] lemma lift_mul (x y) : lift f (x * y) = lift f x * lift f y :=
free_semigroup.rec_on x (λ p, rfl)
(λ p x ih1 ih2, by rw [mul_assoc, lift_of_mul, lift_of_mul, mul_assoc, ih2])
@[to_additive]
theorem lift_unique (f : free_semigroup α → β) (hf : ∀ x y, f (x * y) = f x * f y) :
f = lift (f ∘ of) :=
funext $ λ ⟨x, L⟩, list.rec_on L (λ x, rfl) (λ hd tl ih x,
(hf (of x) (hd, tl)).trans $ congr_arg _ $ ih _) x
end lift
section map
variables {β : Type v} (f : α → β)
/-- The unique semigroup homomorphism that sends `of x` to `of (f x)`. -/
@[to_additive "The unique additive semigroup homomorphism that sends `of x` to `of (f x)`."]
def map : free_semigroup α → free_semigroup β :=
lift $ of ∘ f
@[simp, to_additive] lemma map_of (x) : map f (of x) = of (f x) := rfl
@[simp, to_additive] lemma map_mul (x y) : map f (x * y) = map f x * map f y :=
lift_mul _ _ _
end map
section category
variables {β : Type u}
@[to_additive]
instance : monad free_semigroup :=
{ pure := λ _, of,
bind := λ _ _ x f, lift f x }
/-- Recursor that uses `pure` instead of `of`. -/
@[elab_as_eliminator, to_additive "Recursor that uses `pure` instead of `of`."]
def rec_on' {C : free_semigroup α → Sort l} (x)
(ih1 : ∀ x, C (pure x)) (ih2 : ∀ x y, C (pure x) → C y → C (pure x * y)) :
C x :=
free_semigroup.rec_on x ih1 ih2
@[simp, to_additive]
lemma map_pure (f : α → β) (x) : (f <$> pure x : free_semigroup β) = pure (f x) := rfl
@[simp, to_additive]
lemma map_mul' (f : α → β) (x y : free_semigroup α) :
(f <$> (x * y)) = (f <$> x * f <$> y) :=
map_mul _ _ _
@[simp, to_additive] lemma pure_bind (f : α → free_semigroup β) (x) :
(pure x >>= f) = f x := rfl
@[simp, to_additive]
lemma mul_bind (f : α → free_semigroup β) (x y : free_semigroup α) :
(x * y >>= f) = ((x >>= f) * (y >>= f)) :=
lift_mul _ _ _
@[simp, to_additive] lemma pure_seq {f : α → β} {x : free_semigroup α} :
pure f <*> x = f <$> x := rfl
@[simp, to_additive]
lemma mul_seq {f g : free_semigroup (α → β)} {x : free_semigroup α} :
(f * g) <*> x = (f <*> x) * (g <*> x) :=
mul_bind _ _ _
@[to_additive]
instance : is_lawful_monad free_semigroup.{u} :=
{ pure_bind := λ _ _ _ _, rfl,
bind_assoc := λ α β γ x f g, rec_on' x (λ x, rfl)
(λ x y ih1 ih2, by rw [mul_bind, mul_bind, mul_bind, ih1, ih2]),
id_map := λ α x, rec_on' x (λ _, rfl) (λ x y ih1 ih2, by rw [map_mul', ih1, ih2]) }
/-- `free_semigroup` is traversable. -/
@[to_additive "`free_add_semigroup` is traversable."]
protected def traverse {m : Type u → Type u} [applicative m]
{α β : Type u} (F : α → m β) (x : free_semigroup α) : m (free_semigroup β) :=
rec_on' x (λ x, pure <$> F x) (λ x y ihx ihy, (*) <$> ihx <*> ihy)
@[to_additive]
instance : traversable free_semigroup := ⟨@free_semigroup.traverse⟩
variables {m : Type u → Type u} [applicative m] (F : α → m β)
@[simp, to_additive]
lemma traverse_pure (x) :traverse F (pure x : free_semigroup α) = pure <$> F x := rfl
@[simp, to_additive]
lemma traverse_pure' : traverse F ∘ pure = λ x, (pure <$> F x : m (free_semigroup β)) := rfl
section
variables [is_lawful_applicative m]
@[simp, to_additive] lemma traverse_mul (x y : free_semigroup α) :
traverse F (x * y) = (*) <$> traverse F x <*> traverse F y :=
let ⟨x, L1⟩ := x, ⟨y, L2⟩ := y in
list.rec_on L1 (λ x, rfl) (λ hd tl ih x,
show (*) <$> pure <$> F x <*> traverse F ((hd, tl) * (y, L2) : free_semigroup α) =
(*) <$> ((*) <$> pure <$> F x <*> traverse F (hd, tl)) <*> traverse F (y, L2),
by rw ih; simp only [(∘), (mul_assoc _ _ _).symm] with functor_norm) x
@[simp, to_additive] lemma traverse_mul' :
function.comp (traverse F) ∘ @has_mul.mul (free_semigroup α) _ =
λ x y, (*) <$> traverse F x <*> traverse F y :=
funext $ λ x, funext $ λ y, traverse_mul F x y
end
@[simp, to_additive] lemma traverse_eq (x) : free_semigroup.traverse F x = traverse F x := rfl
@[simp, to_additive] lemma mul_map_seq (x y : free_semigroup α) :
((*) <$> x <*> y : id (free_semigroup α)) = (x * y : free_semigroup α) := rfl
@[to_additive]
instance : is_lawful_traversable free_semigroup.{u} :=
{ id_traverse := λ α x, free_semigroup.rec_on x (λ x, rfl)
(λ x y ih1 ih2, by rw [traverse_mul, ih1, ih2, mul_map_seq]),
comp_traverse := λ F G hf1 hg1 hf2 hg2 α β γ f g x, rec_on' x
(λ x, by resetI; simp only [traverse_pure, traverse_pure'] with functor_norm)
(λ x y ih1 ih2, by resetI; rw [traverse_mul, ih1, ih2, traverse_mul];
simp only [traverse_mul'] with functor_norm),
naturality := λ F G hf1 hg1 hf2 hg2 η α β f x, rec_on' x
(λ x, by simp only [traverse_pure] with functor_norm)
(λ x y ih1 ih2, by resetI; simp only [traverse_mul] with functor_norm; rw [ih1, ih2]),
traverse_eq_map_id := λ α β f x, free_semigroup.rec_on x (λ _, rfl)
(λ x y ih1 ih2, by rw [traverse_mul, ih1, ih2, map_mul', mul_map_seq]; refl),
.. free_semigroup.is_lawful_monad }
end category
@[to_additive]
instance [decidable_eq α] : decidable_eq (free_semigroup α) := prod.decidable_eq
end free_semigroup
/-- Isomorphism between `magma.free_semigroup (free_magma α)` and `free_semigroup α`. -/
@[to_additive "Isomorphism between
`add_magma.free_add_semigroup (free_add_magma α)` and `free_add_semigroup α`."]
def free_semigroup_free_magma (α : Type u) :
magma.free_semigroup (free_magma α) ≃ free_semigroup α :=
{ to_fun :=
magma.free_semigroup.lift (free_magma.lift free_semigroup.of) (free_magma.lift _).map_mul,
inv_fun := free_semigroup.lift (magma.free_semigroup.of ∘ free_magma.of),
left_inv := λ x, magma.free_semigroup.induction_on x $ λ p, by rw magma.free_semigroup.lift_of;
exact free_magma.rec_on' p
(λ x, by rw [free_magma.lift_of, free_semigroup.lift_of])
(λ x y ihx ihy, by rw [mul_hom.map_mul, free_semigroup.lift_mul, ihx, ihy,
magma.free_semigroup.of_mul]),
right_inv := λ x, free_semigroup.rec_on x
(λ x, by rw [free_semigroup.lift_of, magma.free_semigroup.lift_of, free_magma.lift_of])
(λ x y ihx ihy, by rw [free_semigroup.lift_mul, magma.free_semigroup.lift_mul, ihx, ihy]) }
@[simp, to_additive] lemma free_semigroup_free_magma_mul {α : Type u} (x y) :
free_semigroup_free_magma α (x * y) = free_semigroup_free_magma α x *
free_semigroup_free_magma α y :=
magma.free_semigroup.lift_mul _ _ _
|
2d9fa34d79b28e9c9eaa6e873fbad7e5971dae81 | 2eab05920d6eeb06665e1a6df77b3157354316ad | /src/data/set/intervals/unordered_interval.lean | 67f1079cbb8f3685e2f67a8917910d7f83722c83 | [
"Apache-2.0"
] | permissive | ayush1801/mathlib | 78949b9f789f488148142221606bf15c02b960d2 | ce164e28f262acbb3de6281b3b03660a9f744e3c | refs/heads/master | 1,692,886,907,941 | 1,635,270,866,000 | 1,635,270,866,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 8,889 | lean | /-
Copyright (c) 2020 Zhouhang Zhou. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Zhouhang Zhou
-/
import order.bounds
import data.set.intervals.image_preimage
/-!
# Intervals without endpoints ordering
In any decidable linear order `α`, we define the set of elements lying between two elements `a` and
`b` as `Icc (min a b) (max a b)`.
`Icc a b` requires the assumption `a ≤ b` to be meaningful, which is sometimes inconvenient. The
interval as defined in this file is always the set of things lying between `a` and `b`, regardless
of the relative order of `a` and `b`.
For real numbers, `Icc (min a b) (max a b)` is the same as `segment ℝ a b`.
## Notation
We use the localized notation `[a, b]` for `interval a b`. One can open the locale `interval` to
make the notation available.
-/
universe u
open_locale pointwise
namespace set
section linear_order
variables {α : Type u} [linear_order α] {a a₁ a₂ b b₁ b₂ x : α}
/-- `interval a b` is the set of elements lying between `a` and `b`, with `a` and `b` included. -/
def interval (a b : α) := Icc (min a b) (max a b)
localized "notation `[`a `, ` b `]` := set.interval a b" in interval
@[simp] lemma interval_of_le (h : a ≤ b) : [a, b] = Icc a b :=
by rw [interval, min_eq_left h, max_eq_right h]
@[simp] lemma interval_of_ge (h : b ≤ a) : [a, b] = Icc b a :=
by { rw [interval, min_eq_right h, max_eq_left h] }
lemma interval_swap (a b : α) : [a, b] = [b, a] :=
or.elim (le_total a b) (by simp {contextual := tt}) (by simp {contextual := tt})
lemma interval_of_lt (h : a < b) : [a, b] = Icc a b :=
interval_of_le (le_of_lt h)
lemma interval_of_gt (h : b < a) : [a, b] = Icc b a :=
interval_of_ge (le_of_lt h)
lemma interval_of_not_le (h : ¬ a ≤ b) : [a, b] = Icc b a :=
interval_of_gt (lt_of_not_ge h)
lemma interval_of_not_ge (h : ¬ b ≤ a) : [a, b] = Icc a b :=
interval_of_lt (lt_of_not_ge h)
@[simp] lemma interval_self : [a, a] = {a} :=
set.ext $ by simp [le_antisymm_iff, and_comm]
@[simp] lemma nonempty_interval : set.nonempty [a, b] :=
by { simp only [interval, min_le_iff, le_max_iff, nonempty_Icc], left, left, refl }
@[simp] lemma left_mem_interval : a ∈ [a, b] :=
by { rw [interval, mem_Icc], exact ⟨min_le_left _ _, le_max_left _ _⟩ }
@[simp] lemma right_mem_interval : b ∈ [a, b] :=
by { rw interval_swap, exact left_mem_interval }
lemma Icc_subset_interval : Icc a b ⊆ [a, b] :=
by { assume x h, rwa interval_of_le, exact le_trans h.1 h.2 }
lemma Icc_subset_interval' : Icc b a ⊆ [a, b] :=
by { rw interval_swap, apply Icc_subset_interval }
lemma mem_interval_of_le (ha : a ≤ x) (hb : x ≤ b) : x ∈ [a, b] :=
Icc_subset_interval ⟨ha, hb⟩
lemma mem_interval_of_ge (hb : b ≤ x) (ha : x ≤ a) : x ∈ [a, b] :=
Icc_subset_interval' ⟨hb, ha⟩
lemma not_mem_interval_of_lt {c : α} (ha : c < a) (hb : c < b) : c ∉ interval a b :=
not_mem_Icc_of_lt $ lt_min_iff.mpr ⟨ha, hb⟩
lemma not_mem_interval_of_gt {c : α} (ha : a < c) (hb : b < c) : c ∉ interval a b :=
not_mem_Icc_of_gt $ max_lt_iff.mpr ⟨ha, hb⟩
lemma interval_subset_interval (h₁ : a₁ ∈ [a₂, b₂]) (h₂ : b₁ ∈ [a₂, b₂]) : [a₁, b₁] ⊆ [a₂, b₂] :=
Icc_subset_Icc (le_min h₁.1 h₂.1) (max_le h₁.2 h₂.2)
lemma interval_subset_interval_iff_mem : [a₁, b₁] ⊆ [a₂, b₂] ↔ a₁ ∈ [a₂, b₂] ∧ b₁ ∈ [a₂, b₂] :=
iff.intro (λh, ⟨h left_mem_interval, h right_mem_interval⟩) (λ h, interval_subset_interval h.1 h.2)
lemma interval_subset_interval_iff_le :
[a₁, b₁] ⊆ [a₂, b₂] ↔ min a₂ b₂ ≤ min a₁ b₁ ∧ max a₁ b₁ ≤ max a₂ b₂ :=
by { rw [interval, interval, Icc_subset_Icc_iff], exact min_le_max }
lemma interval_subset_interval_right (h : x ∈ [a, b]) : [x, b] ⊆ [a, b] :=
interval_subset_interval h right_mem_interval
lemma interval_subset_interval_left (h : x ∈ [a, b]) : [a, x] ⊆ [a, b] :=
interval_subset_interval left_mem_interval h
lemma bdd_below_bdd_above_iff_subset_interval (s : set α) :
bdd_below s ∧ bdd_above s ↔ ∃ a b, s ⊆ [a, b] :=
begin
rw [bdd_below_bdd_above_iff_subset_Icc],
split,
{ rintro ⟨a, b, h⟩, exact ⟨a, b, λ x hx, Icc_subset_interval (h hx)⟩ },
{ rintro ⟨a, b, h⟩, exact ⟨min a b, max a b, h⟩ }
end
/-- The open-closed interval with unordered bounds. -/
def interval_oc : α → α → set α := λ a b, Ioc (min a b) (max a b)
-- Below is a capital iota
localized "notation `Ι` := set.interval_oc" in interval
lemma interval_oc_of_le (h : a ≤ b) : Ι a b = Ioc a b :=
by simp [interval_oc, h]
lemma interval_oc_of_lt (h : b < a) : Ι a b = Ioc b a :=
by simp [interval_oc, le_of_lt h]
lemma forall_interval_oc_iff {P : α → Prop} :
(∀ x ∈ Ι a b, P x) ↔ (∀ x ∈ Ioc a b, P x) ∧ (∀ x ∈ Ioc b a, P x) :=
by { dsimp [interval_oc], cases le_total a b with hab hab ; simp [hab] }
end linear_order
open_locale interval
section ordered_add_comm_group
variables {α : Type u} [linear_ordered_add_comm_group α] (a b c x y : α)
@[simp] lemma preimage_const_add_interval : (λ x, a + x) ⁻¹' [b, c] = [b - a, c - a] :=
by simp only [interval, preimage_const_add_Icc, min_sub_sub_right, max_sub_sub_right]
@[simp] lemma preimage_add_const_interval : (λ x, x + a) ⁻¹' [b, c] = [b - a, c - a] :=
by simpa only [add_comm] using preimage_const_add_interval a b c
@[simp] lemma preimage_neg_interval : - [a, b] = [-a, -b] :=
by simp only [interval, preimage_neg_Icc, min_neg_neg, max_neg_neg]
@[simp] lemma preimage_sub_const_interval : (λ x, x - a) ⁻¹' [b, c] = [b + a, c + a] :=
by simp [sub_eq_add_neg]
@[simp] lemma preimage_const_sub_interval : (λ x, a - x) ⁻¹' [b, c] = [a - b, a - c] :=
by { rw [interval, interval, preimage_const_sub_Icc],
simp only [sub_eq_add_neg, min_add_add_left, max_add_add_left, min_neg_neg, max_neg_neg], }
@[simp] lemma image_const_add_interval : (λ x, a + x) '' [b, c] = [a + b, a + c] :=
by simp [add_comm]
@[simp] lemma image_add_const_interval : (λ x, x + a) '' [b, c] = [b + a, c + a] :=
by simp
@[simp] lemma image_const_sub_interval : (λ x, a - x) '' [b, c] = [a - b, a - c] :=
by simp [sub_eq_add_neg, image_comp (λ x, a + x) (λ x, -x)]
@[simp] lemma image_sub_const_interval : (λ x, x - a) '' [b, c] = [b - a, c - a] :=
by simp [sub_eq_add_neg, add_comm]
lemma image_neg_interval : has_neg.neg '' [a, b] = [-a, -b] := by simp
variables {a b c x y}
/-- If `[x, y]` is a subinterval of `[a, b]`, then the distance between `x` and `y`
is less than or equal to that of `a` and `b` -/
lemma abs_sub_le_of_subinterval (h : [x, y] ⊆ [a, b]) : |y - x| ≤ |b - a| :=
begin
rw [← max_sub_min_eq_abs, ← max_sub_min_eq_abs],
rw [interval_subset_interval_iff_le] at h,
exact sub_le_sub h.2 h.1,
end
/-- If `x ∈ [a, b]`, then the distance between `a` and `x` is less than or equal to
that of `a` and `b` -/
lemma abs_sub_left_of_mem_interval (h : x ∈ [a, b]) : |x - a| ≤ |b - a| :=
abs_sub_le_of_subinterval (interval_subset_interval_left h)
/-- If `x ∈ [a, b]`, then the distance between `x` and `b` is less than or equal to
that of `a` and `b` -/
lemma abs_sub_right_of_mem_interval (h : x ∈ [a, b]) : |b - x| ≤ |b - a| :=
abs_sub_le_of_subinterval (interval_subset_interval_right h)
end ordered_add_comm_group
section linear_ordered_field
variables {k : Type u} [linear_ordered_field k] {a : k}
@[simp] lemma preimage_mul_const_interval (ha : a ≠ 0) (b c : k) :
(λ x, x * a) ⁻¹' [b, c] = [b / a, c / a] :=
(lt_or_gt_of_ne ha).elim
(λ ha, by simp [interval, ha, ha.le, min_div_div_right_of_nonpos, max_div_div_right_of_nonpos])
(λ (ha : 0 < a), by simp [interval, ha, ha.le, min_div_div_right, max_div_div_right])
@[simp] lemma preimage_const_mul_interval (ha : a ≠ 0) (b c : k) :
(λ x, a * x) ⁻¹' [b, c] = [b / a, c / a] :=
by simp only [← preimage_mul_const_interval ha, mul_comm]
@[simp] lemma preimage_div_const_interval (ha : a ≠ 0) (b c : k) :
(λ x, x / a) ⁻¹' [b, c] = [b * a, c * a] :=
by simp only [div_eq_mul_inv, preimage_mul_const_interval (inv_ne_zero ha), inv_inv₀]
@[simp] lemma image_mul_const_interval (a b c : k) : (λ x, x * a) '' [b, c] = [b * a, c * a] :=
if ha : a = 0 then by simp [ha] else
calc (λ x, x * a) '' [b, c] = (λ x, x * a⁻¹) ⁻¹' [b, c] :
(units.mk0 a ha).mul_right.image_eq_preimage _
... = (λ x, x / a) ⁻¹' [b, c] : by simp only [div_eq_mul_inv]
... = [b * a, c * a] : preimage_div_const_interval ha _ _
@[simp] lemma image_const_mul_interval (a b c : k) : (λ x, a * x) '' [b, c] = [a * b, a * c] :=
by simpa only [mul_comm] using image_mul_const_interval a b c
@[simp] lemma image_div_const_interval (a b c : k) : (λ x, x / a) '' [b, c] = [b / a, c / a] :=
by simp only [div_eq_mul_inv, image_mul_const_interval]
end linear_ordered_field
end set
|
08d950127bb9527f899f029e0e81e1c8747b2dbb | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /archive/imo/imo1987_q1.lean | ffae4fbd202d716945495d85fa4d5e5ee59a1f2a | [
"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 | 4,288 | lean | /-
Copyright (c) 2021 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import data.fintype.big_operators
import data.fintype.perm
import data.fintype.prod
import dynamics.fixed_points.basic
/-!
# Formalization of IMO 1987, Q1
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
Let $p_{n, k}$ be the number of permutations of a set of cardinality `n ≥ 1` that fix exactly `k`
elements. Prove that $∑_{k=0}^n k p_{n,k}=n!$.
To prove this identity, we show that both sides are equal to the cardinality of the set
`{(x : α, σ : perm α) | σ x = x}`, regrouping by `card (fixed_points σ)` for the left hand side and
by `x` for the right hand side.
The original problem assumes `n ≥ 1`. It turns out that a version with `n * (n - 1)!` in the RHS
holds true for `n = 0` as well, so we first prove it, then deduce the original version in the case
`n ≥ 1`. -/
variables (α : Type*) [fintype α] [decidable_eq α]
open_locale big_operators nat
open equiv fintype function finset (range sum_const) set (Iic)
namespace imo1987_q1
/-- The set of pairs `(x : α, σ : perm α)` such that `σ x = x` is equivalent to the set of pairs
`(x : α, σ : perm {x}ᶜ)`. -/
def fixed_points_equiv :
{σx : α × perm α // σx.2 σx.1 = σx.1} ≃ Σ x : α, perm ({x}ᶜ : set α) :=
calc {σx : α × perm α // σx.2 σx.1 = σx.1} ≃ Σ x : α, {σ : perm α // σ x = x} :
set_prod_equiv_sigma _
... ≃ Σ x : α, {σ : perm α // ∀ y : ({x} : set α), σ y = equiv.refl ↥({x} : set α) y} :
sigma_congr_right (λ x, equiv.set.of_eq $ by { simp only [set_coe.forall], dsimp, simp })
... ≃ Σ x : α, perm ({x}ᶜ : set α) :
sigma_congr_right (λ x, by apply equiv.set.compl)
theorem card_fixed_points :
card {σx : α × perm α // σx.2 σx.1 = σx.1} = card α * (card α - 1)! :=
by simp [card_congr (fixed_points_equiv α), card_perm, finset.filter_not, finset.card_sdiff,
finset.filter_eq', finset.card_univ]
/-- Given `α : Type*` and `k : ℕ`, `fiber α k` is the set of permutations of `α` with exactly `k`
fixed points. -/
@[derive fintype]
def fiber (k : ℕ) : set (perm α) := {σ : perm α | card (fixed_points σ) = k}
@[simp] lemma mem_fiber {σ : perm α} {k : ℕ} : σ ∈ fiber α k ↔ card (fixed_points σ) = k := iff.rfl
/-- `p α k` is the number of permutations of `α` with exactly `k` fixed points. -/
def p (k : ℕ) := card (fiber α k)
/-- The set of triples `(k ≤ card α, σ ∈ fiber α k, x ∈ fixed_points σ)` is equivalent
to the set of pairs `(x : α, σ : perm α)` such that `σ x = x`. The equivalence sends
`(k, σ, x)` to `(x, σ)` and `(x, σ)` to `(card (fixed_points σ), σ, x)`.
It is easy to see that the cardinality of the LHS is given by
`∑ k : fin (card α + 1), k * p α k`. -/
def fixed_points_equiv' :
(Σ (k : fin (card α + 1)) (σ : fiber α k), fixed_points σ.1) ≃
{σx : α × perm α // σx.2 σx.1 = σx.1} :=
{ to_fun := λ p, ⟨⟨p.2.2, p.2.1⟩, p.2.2.2⟩,
inv_fun := λ p,
⟨⟨card (fixed_points p.1.2), (card_subtype_le _).trans_lt (nat.lt_succ_self _)⟩,
⟨p.1.2, rfl⟩, ⟨p.1.1, p.2⟩⟩,
left_inv := λ ⟨⟨k, hk⟩, ⟨σ, hσ⟩, ⟨x, hx⟩⟩, by { simp only [mem_fiber, fin.coe_mk] at hσ,
subst k, refl },
right_inv := λ ⟨⟨x, σ⟩, h⟩, rfl }
/-- Main statement for any `(α : Type*) [fintype α]`. -/
theorem main_fintype :
∑ k in range (card α + 1), k * p α k = card α * (card α - 1)! :=
have A : ∀ k (σ : fiber α k), card (fixed_points ⇑(↑σ : perm α)) = k := λ k σ, σ.2,
by simpa [A, ← fin.sum_univ_eq_sum_range, -card_of_finset, finset.card_univ,
card_fixed_points, mul_comm] using card_congr (fixed_points_equiv' α)
/-- Main statement for permutations of `fin n`, a version that works for `n = 0`. -/
theorem main₀ (n : ℕ) :
∑ k in range (n + 1), k * p (fin n) k = n * (n - 1)! :=
by simpa using main_fintype (fin n)
/-- Main statement for permutations of `fin n`. -/
theorem main {n : ℕ} (hn : 1 ≤ n) :
∑ k in range (n + 1), k * p (fin n) k = n! :=
by rw [main₀, nat.mul_factorial_pred (zero_lt_one.trans_le hn)]
end imo1987_q1
|
857690e1ba9670674c8c464851135158654acd2c | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/algebra/gcd_monoid/integrally_closed.lean | 341d93937c36b3225ba984bfee3ea233ca360706 | [
"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 | 1,689 | 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 algebra.gcd_monoid.basic
import ring_theory.integrally_closed
import ring_theory.polynomial.eisenstein
/-!
# GCD domains are integrally closed
-/
open_locale big_operators polynomial
variables {R A : Type*} [comm_ring R] [is_domain R] [gcd_monoid R] [comm_ring A] [algebra R A]
lemma is_localization.surj_of_gcd_domain (M : submonoid R) [is_localization M A] (z : A) :
∃ a b : R, is_unit (gcd a b) ∧ z * algebra_map R A b = algebra_map R A a :=
begin
obtain ⟨x, ⟨y, hy⟩, rfl⟩ := is_localization.mk'_surjective M z,
obtain ⟨x', y', hx', hy', hu⟩ := extract_gcd x y,
use [x', y', hu],
rw [mul_comm, is_localization.mul_mk'_eq_mk'_of_mul],
convert is_localization.mk'_mul_cancel_left _ _ using 2,
{ rw [subtype.coe_mk, hy', ← mul_comm y', mul_assoc], conv_lhs { rw hx' } },
{ apply_instance },
end
@[priority 100]
instance gcd_monoid.to_is_integrally_closed : is_integrally_closed R :=
⟨λ X ⟨p, hp₁, hp₂⟩, begin
obtain ⟨x, y, hg, he⟩ := is_localization.surj_of_gcd_domain (non_zero_divisors R) X,
have := polynomial.dvd_pow_nat_degree_of_eval₂_eq_zero
(is_fraction_ring.injective R $ fraction_ring R) hp₁ y x _ hp₂ (by rw [mul_comm, he]),
have : is_unit y,
{ rw [is_unit_iff_dvd_one, ← one_pow],
exact (dvd_gcd this $ dvd_refl y).trans (gcd_pow_left_dvd_pow_gcd.trans $
pow_dvd_pow_of_dvd (is_unit_iff_dvd_one.1 hg) _) },
use x * (this.unit⁻¹ : _),
erw [map_mul, ← units.coe_map_inv, eq_comm, units.eq_mul_inv_iff_mul_eq],
exact he,
end⟩
|
7f213839e8c15b1e7026b619fb2ea7bdc09dbb4d | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/category_theory/const.lean | 13211cfe93cca49fa90edd6ad0bc7f307f4673b9 | [
"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 | 3,373 | lean | /-
Copyright (c) 2018 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.opposites
/-!
# The constant functor
`const J : C ⥤ (J ⥤ C)` is the functor that sends an object `X : C` to the functor `J ⥤ C` sending
every object in `J` to `X`, and every morphism to `𝟙 X`.
When `J` is nonempty, `const` is faithful.
We have `(const J).obj X ⋙ F ≅ (const J).obj (F.obj X)` for any `F : C ⥤ D`.
-/
-- declare the `v`'s first; see `category_theory.category` for an explanation
universes v₁ v₂ v₃ u₁ u₂ u₃
open category_theory
namespace category_theory.functor
variables (J : Type u₁) [category.{v₁} J]
variables {C : Type u₂} [category.{v₂} C]
/--
The functor sending `X : C` to the constant functor `J ⥤ C` sending everything to `X`.
-/
def const : C ⥤ (J ⥤ C) :=
{ obj := λ X,
{ obj := λ j, X,
map := λ j j' f, 𝟙 X },
map := λ X Y f, { app := λ j, f } }
namespace const
open opposite
variables {J}
@[simp] lemma obj_obj (X : C) (j : J) : ((const J).obj X).obj j = X := rfl
@[simp] lemma obj_map (X : C) {j j' : J} (f : j ⟶ j') : ((const J).obj X).map f = 𝟙 X := rfl
@[simp] lemma map_app {X Y : C} (f : X ⟶ Y) (j : J) : ((const J).map f).app j = f := rfl
/--
The contant functor `Jᵒᵖ ⥤ Cᵒᵖ` sending everything to `op X`
is (naturally isomorphic to) the opposite of the constant functor `J ⥤ C` sending everything to `X`.
-/
def op_obj_op (X : C) :
(const Jᵒᵖ).obj (op X) ≅ ((const J).obj X).op :=
{ hom := { app := λ j, 𝟙 _ },
inv := { app := λ j, 𝟙 _ } }
@[simp] lemma op_obj_op_hom_app (X : C) (j : Jᵒᵖ) : (op_obj_op X).hom.app j = 𝟙 _ := rfl
@[simp] lemma op_obj_op_inv_app (X : C) (j : Jᵒᵖ) : (op_obj_op X).inv.app j = 𝟙 _ := rfl
/--
The contant functor `Jᵒᵖ ⥤ C` sending everything to `unop X`
is (naturally isomorphic to) the opposite of
the constant functor `J ⥤ Cᵒᵖ` sending everything to `X`.
-/
def op_obj_unop (X : Cᵒᵖ) :
(const Jᵒᵖ).obj (unop X) ≅ ((const J).obj X).left_op :=
{ hom := { app := λ j, 𝟙 _ },
inv := { app := λ j, 𝟙 _ } }
-- Lean needs some help with universes here.
@[simp] lemma op_obj_unop_hom_app (X : Cᵒᵖ) (j : Jᵒᵖ) : (op_obj_unop.{v₁ v₂} X).hom.app j = 𝟙 _ :=
rfl
@[simp] lemma op_obj_unop_inv_app (X : Cᵒᵖ) (j : Jᵒᵖ) : (op_obj_unop.{v₁ v₂} X).inv.app j = 𝟙 _ :=
rfl
@[simp] lemma unop_functor_op_obj_map (X : Cᵒᵖ) {j₁ j₂ : J} (f : j₁ ⟶ j₂) :
(unop ((functor.op (const J)).obj X)).map f = 𝟙 (unop X) := rfl
end const
section
variables {D : Type u₃} [category.{v₃} D]
/-- These are actually equal, of course, but not definitionally equal
(the equality requires F.map (𝟙 _) = 𝟙 _). A natural isomorphism is
more convenient than an equality between functors (compare id_to_iso). -/
@[simps] def const_comp (X : C) (F : C ⥤ D) :
(const J).obj X ⋙ F ≅ (const J).obj (F.obj X) :=
{ hom := { app := λ _, 𝟙 _ },
inv := { app := λ _, 𝟙 _ } }
/-- If `J` is nonempty, then the constant functor over `J` is faithful. -/
instance [nonempty J] : faithful (const J : C ⥤ J ⥤ C) :=
{ map_injective' := λ X Y f g e, nat_trans.congr_app e (classical.arbitrary J) }
end
end category_theory.functor
|
62fc11467ffdf8a43a0093d79fed1d793d8a9aa4 | d9d511f37a523cd7659d6f573f990e2a0af93c6f | /src/data/fintype/card.lean | a10a5f9cb571c170d65c43dc6dbfd1dd48a34a74 | [
"Apache-2.0"
] | permissive | hikari0108/mathlib | b7ea2b7350497ab1a0b87a09d093ecc025a50dfa | a9e7d333b0cfd45f13a20f7b96b7d52e19fa2901 | refs/heads/master | 1,690,483,608,260 | 1,631,541,580,000 | 1,631,541,580,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 16,925 | 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.fintype.basic
import algebra.big_operators.ring
/-!
Results about "big operations" over a `fintype`, and consequent
results about cardinalities of certain types.
## Implementation note
This content had previously been in `data.fintype.basic`, but was moved here to avoid
requiring `algebra.big_operators` (and hence many other imports) as a
dependency of `fintype`.
However many of the results here really belong in `algebra.big_operators.basic`
and should be moved at some point.
-/
universes u v
variables {α : Type*} {β : Type*} {γ : Type*}
open_locale big_operators
namespace fintype
@[to_additive]
lemma prod_bool [comm_monoid α] (f : bool → α) : ∏ b, f b = f tt * f ff := by simp
lemma card_eq_sum_ones {α} [fintype α] : fintype.card α = ∑ a : α, 1 :=
finset.card_eq_sum_ones _
section
open finset
variables {ι : Type*} [decidable_eq ι] [fintype ι]
@[to_additive]
lemma prod_extend_by_one [comm_monoid α] (s : finset ι) (f : ι → α) :
∏ i, (if i ∈ s then f i else 1) = ∏ i in s, f i :=
by rw [← prod_filter, filter_mem_eq_inter, univ_inter]
end
section
variables {M : Type*} [fintype α] [comm_monoid M]
@[to_additive]
lemma prod_eq_one (f : α → M) (h : ∀ a, f a = 1) :
(∏ a, f a) = 1 :=
finset.prod_eq_one $ λ a ha, h a
@[to_additive]
lemma prod_congr (f g : α → M) (h : ∀ a, f a = g a) :
(∏ a, f a) = ∏ a, g a :=
finset.prod_congr rfl $ λ a ha, h a
@[to_additive]
lemma prod_eq_single {f : α → M} (a : α) (h : ∀ x ≠ a, f x = 1) :
(∏ x, f x) = f a :=
finset.prod_eq_single a (λ x _ hx, h x hx) $ λ ha, (ha (finset.mem_univ a)).elim
@[to_additive]
lemma prod_eq_mul {f : α → M} (a b : α) (h₁ : a ≠ b) (h₂ : ∀ x, x ≠ a ∧ x ≠ b → f x = 1) :
(∏ x, f x) = (f a) * (f b) :=
begin
apply finset.prod_eq_mul a b h₁ (λ x _ hx, h₂ x hx);
exact λ hc, (hc (finset.mem_univ _)).elim
end
/-- If a product of a `finset` of a subsingleton type has a given
value, so do the terms in that product. -/
@[to_additive "If a sum of a `finset` of a subsingleton type has a given
value, so do the terms in that sum."]
lemma eq_of_subsingleton_of_prod_eq {ι : Type*} [subsingleton ι] {s : finset ι}
{f : ι → M} {b : M} (h : ∏ i in s, f i = b) : ∀ i ∈ s, f i = b :=
finset.eq_of_card_le_one_of_prod_eq (finset.card_le_one_of_subsingleton s) h
end
end fintype
open finset
section
variables {M : Type*} [fintype α] [comm_monoid M]
@[simp, to_additive]
lemma fintype.prod_option (f : option α → M) : ∏ i, f i = f none * ∏ i, f (some i) :=
show ((finset.insert_none _).1.map f).prod = _,
by simp only [finset.prod, finset.insert_none, multiset.map_cons, multiset.prod_cons,
multiset.map_map]
end
@[to_additive]
theorem fin.prod_univ_def [comm_monoid β] {n : ℕ} (f : fin n → β) :
∏ i, f i = ((list.fin_range n).map f).prod :=
by simp [fin.univ_def, finset.fin_range]
@[to_additive]
theorem finset.prod_range [comm_monoid β] {n : ℕ} (f : ℕ → β) :
∏ i in finset.range n, f i = ∏ i : fin n, f i :=
begin
fapply @finset.prod_bij' _ _ _ _ _ _,
exact λ k w, ⟨k, (by simpa using w)⟩,
swap 3,
exact λ a m, a,
swap 3,
exact λ a m, by simpa using a.2,
all_goals { tidy, },
end
@[to_additive]
theorem fin.prod_of_fn [comm_monoid β] {n : ℕ} (f : fin n → β) :
(list.of_fn f).prod = ∏ i, f i :=
by rw [list.of_fn_eq_map, fin.prod_univ_def]
/-- A product of a function `f : fin 0 → β` is `1` because `fin 0` is empty -/
@[to_additive "A sum of a function `f : fin 0 → β` is `0` because `fin 0` is empty"]
theorem fin.prod_univ_zero [comm_monoid β] (f : fin 0 → β) : ∏ i, f i = 1 := rfl
/-- A product of a function `f : fin (n + 1) → β` over all `fin (n + 1)`
is the product of `f x`, for some `x : fin (n + 1)` times the remaining product -/
theorem fin.prod_univ_succ_above [comm_monoid β] {n : ℕ} (f : fin (n + 1) → β) (x : fin (n + 1)) :
∏ i, f i = f x * ∏ i : fin n, f (x.succ_above i) :=
begin
rw [fin.univ_succ_above, finset.prod_insert, finset.prod_image],
{ intros x _ y _ hxy, exact fin.succ_above_right_inj.mp hxy },
{ simp [fin.succ_above_ne] }
end
/-- A sum of a function `f : fin (n + 1) → β` over all `fin (n + 1)`
is the sum of `f x`, for some `x : fin (n + 1)` plus the remaining product -/
theorem fin.sum_univ_succ_above [add_comm_monoid β] {n : ℕ} (f : fin (n + 1) → β)
(x : fin (n + 1)) :
∑ i, f i = f x + ∑ i : fin n, f (x.succ_above i) :=
by apply @fin.prod_univ_succ_above (multiplicative β)
attribute [to_additive] fin.prod_univ_succ_above
/-- A product of a function `f : fin (n + 1) → β` over all `fin (n + 1)`
is the product of `f 0` plus the remaining product -/
theorem fin.prod_univ_succ [comm_monoid β] {n : ℕ} (f : fin (n + 1) → β) :
∏ i, f i = f 0 * ∏ i : fin n, f i.succ :=
fin.prod_univ_succ_above f 0
/-- A sum of a function `f : fin (n + 1) → β` over all `fin (n + 1)`
is the sum of `f 0` plus the remaining product -/
theorem fin.sum_univ_succ [add_comm_monoid β] {n : ℕ} (f : fin (n + 1) → β) :
∑ i, f i = f 0 + ∑ i : fin n, f i.succ :=
fin.sum_univ_succ_above f 0
attribute [to_additive] fin.prod_univ_succ
/-- A product of a function `f : fin (n + 1) → β` over all `fin (n + 1)`
is the product of `f (fin.last n)` plus the remaining product -/
theorem fin.prod_univ_cast_succ [comm_monoid β] {n : ℕ} (f : fin (n + 1) → β) :
∏ i, f i = (∏ i : fin n, f i.cast_succ) * f (fin.last n) :=
by simpa [mul_comm] using fin.prod_univ_succ_above f (fin.last n)
/-- A sum of a function `f : fin (n + 1) → β` over all `fin (n + 1)`
is the sum of `f (fin.last n)` plus the remaining sum -/
theorem fin.sum_univ_cast_succ [add_comm_monoid β] {n : ℕ} (f : fin (n + 1) → β) :
∑ i, f i = ∑ i : fin n, f i.cast_succ + f (fin.last n) :=
by apply @fin.prod_univ_cast_succ (multiplicative β)
attribute [to_additive] fin.prod_univ_cast_succ
open finset
@[simp] theorem fintype.card_sigma {α : Type*} (β : α → Type*)
[fintype α] [∀ a, fintype (β a)] :
fintype.card (sigma β) = ∑ a, fintype.card (β a) :=
card_sigma _ _
@[simp] lemma finset.card_pi [decidable_eq α] {δ : α → Type*}
(s : finset α) (t : Π a, finset (δ a)) :
(s.pi t).card = ∏ a in s, card (t a) :=
multiset.card_pi _ _
@[simp] lemma fintype.card_pi_finset [decidable_eq α] [fintype α]
{δ : α → Type*} (t : Π a, finset (δ a)) :
(fintype.pi_finset t).card = ∏ a, card (t a) :=
by simp [fintype.pi_finset, card_map]
@[simp] lemma fintype.card_pi {β : α → Type*} [decidable_eq α] [fintype α]
[f : Π a, fintype (β a)] : fintype.card (Π a, β a) = ∏ a, fintype.card (β a) :=
fintype.card_pi_finset _
-- FIXME ouch, this should be in the main file.
@[simp] lemma fintype.card_fun [decidable_eq α] [fintype α] [fintype β] :
fintype.card (α → β) = fintype.card β ^ fintype.card α :=
by rw [fintype.card_pi, finset.prod_const]; refl
@[simp] lemma card_vector [fintype α] (n : ℕ) :
fintype.card (vector α n) = fintype.card α ^ n :=
by rw fintype.of_equiv_card; simp
@[simp, to_additive]
lemma finset.prod_attach_univ [fintype α] [comm_monoid β] (f : {a : α // a ∈ @univ α _} → β) :
∏ x in univ.attach, f x = ∏ x, f ⟨x, (mem_univ _)⟩ :=
fintype.prod_equiv (equiv.subtype_univ_equiv (λ x, mem_univ _)) _ _ (λ x, by simp)
/-- Taking a product over `univ.pi t` is the same as taking the product over `fintype.pi_finset t`.
`univ.pi t` and `fintype.pi_finset t` are essentially the same `finset`, but differ
in the type of their element, `univ.pi t` is a `finset (Π a ∈ univ, t a)` and
`fintype.pi_finset t` is a `finset (Π a, t a)`. -/
@[to_additive "Taking a sum over `univ.pi t` is the same as taking the sum over
`fintype.pi_finset t`. `univ.pi t` and `fintype.pi_finset t` are essentially the same `finset`,
but differ in the type of their element, `univ.pi t` is a `finset (Π a ∈ univ, t a)` and
`fintype.pi_finset t` is a `finset (Π a, t a)`."]
lemma finset.prod_univ_pi [decidable_eq α] [fintype α] [comm_monoid β]
{δ : α → Type*} {t : Π (a : α), finset (δ a)}
(f : (Π (a : α), a ∈ (univ : finset α) → δ a) → β) :
∏ x in univ.pi t, f x = ∏ x in fintype.pi_finset t, f (λ a _, x a) :=
prod_bij (λ x _ a, x a (mem_univ _))
(by simp)
(by simp)
(by simp [function.funext_iff] {contextual := tt})
(λ x hx, ⟨λ a _, x a, by simp * at *⟩)
/-- The product over `univ` of a sum can be written as a sum over the product of sets,
`fintype.pi_finset`. `finset.prod_sum` is an alternative statement when the product is not
over `univ` -/
lemma finset.prod_univ_sum [decidable_eq α] [fintype α] [comm_semiring β] {δ : α → Type u_1}
[Π (a : α), decidable_eq (δ a)] {t : Π (a : α), finset (δ a)}
{f : Π (a : α), δ a → β} :
∏ a, ∑ b in t a, f a b = ∑ p in fintype.pi_finset t, ∏ x, f x (p x) :=
by simp only [finset.prod_attach_univ, prod_sum, finset.sum_univ_pi]
/-- Summing `a^s.card * b^(n-s.card)` over all finite subsets `s` of a fintype of cardinality `n`
gives `(a + b)^n`. The "good" proof involves expanding along all coordinates using the fact that
`x^n` is multilinear, but multilinear maps are only available now over rings, so we give instead
a proof reducing to the usual binomial theorem to have a result over semirings. -/
lemma fintype.sum_pow_mul_eq_add_pow
(α : Type*) [fintype α] {R : Type*} [comm_semiring R] (a b : R) :
∑ s : finset α, a ^ s.card * b ^ (fintype.card α - s.card) =
(a + b) ^ (fintype.card α) :=
finset.sum_pow_mul_eq_add_pow _ _ _
lemma fin.sum_pow_mul_eq_add_pow {n : ℕ} {R : Type*} [comm_semiring R] (a b : R) :
∑ s : finset (fin n), a ^ s.card * b ^ (n - s.card) = (a + b) ^ n :=
by simpa using fintype.sum_pow_mul_eq_add_pow (fin n) a b
lemma fin.prod_const [comm_monoid α] (n : ℕ) (x : α) : ∏ i : fin n, x = x ^ n := by simp
lemma fin.sum_const [add_comm_monoid α] (n : ℕ) (x : α) : ∑ i : fin n, x = n • x := by simp
@[to_additive]
lemma function.bijective.prod_comp [fintype α] [fintype β] [comm_monoid γ] {f : α → β}
(hf : function.bijective f) (g : β → γ) :
∏ i, g (f i) = ∏ i, g i :=
fintype.prod_bijective f hf _ _ (λ x, rfl)
@[to_additive]
lemma equiv.prod_comp [fintype α] [fintype β] [comm_monoid γ] (e : α ≃ β) (f : β → γ) :
∏ i, f (e i) = ∏ i, f i :=
e.bijective.prod_comp f
/-- It is equivalent to sum a function over `fin n` or `finset.range n`. -/
@[to_additive]
lemma fin.prod_univ_eq_prod_range [comm_monoid α] (f : ℕ → α) (n : ℕ) :
∏ i : fin n, f i = ∏ i in range n, f i :=
calc (∏ i : fin n, f i) = ∏ i : {x // x ∈ range n}, f i :
((equiv.fin_equiv_subtype n).trans
(equiv.subtype_equiv_right (λ _, mem_range.symm))).prod_comp (f ∘ coe)
... = ∏ i in range n, f i : by rw [← attach_eq_univ, prod_attach]
@[to_additive]
lemma finset.prod_fin_eq_prod_range [comm_monoid β] {n : ℕ} (c : fin n → β) :
∏ i, c i = ∏ i in finset.range n, if h : i < n then c ⟨i, h⟩ else 1 :=
begin
rw [← fin.prod_univ_eq_prod_range, finset.prod_congr rfl],
rintros ⟨i, hi⟩ _,
simp only [fin.coe_eq_val, hi, dif_pos]
end
@[to_additive]
lemma finset.prod_to_finset_eq_subtype {M : Type*} [comm_monoid M] [fintype α]
(p : α → Prop) [decidable_pred p] (f : α → M) :
∏ a in {x | p x}.to_finset, f a = ∏ a : subtype p, f a :=
by { rw ← finset.prod_subtype, simp }
@[to_additive] lemma finset.prod_fiberwise [decidable_eq β] [fintype β] [comm_monoid γ]
(s : finset α) (f : α → β) (g : α → γ) :
∏ b : β, ∏ a in s.filter (λ a, f a = b), g a = ∏ a in s, g a :=
finset.prod_fiberwise_of_maps_to (λ x _, mem_univ _) _
@[to_additive]
lemma fintype.prod_fiberwise [fintype α] [decidable_eq β] [fintype β] [comm_monoid γ]
(f : α → β) (g : α → γ) :
(∏ b : β, ∏ a : {a // f a = b}, g (a : α)) = ∏ a, g a :=
begin
rw [← (equiv.sigma_preimage_equiv f).prod_comp, ← univ_sigma_univ, prod_sigma],
refl
end
lemma fintype.prod_dite [fintype α] {p : α → Prop} [decidable_pred p]
[comm_monoid β] (f : Π (a : α) (ha : p a), β) (g : Π (a : α) (ha : ¬p a), β) :
(∏ a, dite (p a) (f a) (g a)) = (∏ a : {a // p a}, f a a.2) * (∏ a : {a // ¬p a}, g a a.2) :=
begin
simp only [prod_dite, attach_eq_univ],
congr' 1,
{ convert (equiv.subtype_equiv_right _).prod_comp (λ x : {x // p x}, f x x.2),
simp },
{ convert (equiv.subtype_equiv_right _).prod_comp (λ x : {x // ¬p x}, g x x.2),
simp }
end
section
open finset
variables {α₁ : Type*} {α₂ : Type*} {M : Type*} [fintype α₁] [fintype α₂] [comm_monoid M]
@[to_additive]
lemma fintype.prod_sum_elim (f : α₁ → M) (g : α₂ → M) :
(∏ x, sum.elim f g x) = (∏ a₁, f a₁) * (∏ a₂, g a₂) :=
by { classical, rw [univ_sum_type, prod_sum_elim] }
@[to_additive]
lemma fintype.prod_sum_type (f : α₁ ⊕ α₂ → M) :
(∏ x, f x) = (∏ a₁, f (sum.inl a₁)) * (∏ a₂, f (sum.inr a₂)) :=
by simp only [← fintype.prod_sum_elim, sum.elim_comp_inl_inr]
end
namespace list
lemma prod_take_of_fn [comm_monoid α] {n : ℕ} (f : fin n → α) (i : ℕ) :
((of_fn f).take i).prod = ∏ j in finset.univ.filter (λ (j : fin n), j.val < i), f j :=
begin
have A : ∀ (j : fin n), ¬ ((j : ℕ) < 0) := λ j, not_lt_bot,
induction i with i IH, { simp [A] },
by_cases h : i < n,
{ have : i < length (of_fn f), by rwa [length_of_fn f],
rw prod_take_succ _ _ this,
have A : ((finset.univ : finset (fin n)).filter (λ j, j.val < i + 1))
= ((finset.univ : finset (fin n)).filter (λ j, j.val < i)) ∪ {(⟨i, h⟩ : fin n)},
by { ext j, simp [nat.lt_succ_iff_lt_or_eq, fin.ext_iff, - add_comm] },
have B : _root_.disjoint (finset.filter (λ (j : fin n), j.val < i) finset.univ)
(singleton (⟨i, h⟩ : fin n)), by simp,
rw [A, finset.prod_union B, IH],
simp },
{ have A : (of_fn f).take i = (of_fn f).take i.succ,
{ rw ← length_of_fn f at h,
have : length (of_fn f) ≤ i := not_lt.mp h,
rw [take_all_of_le this, take_all_of_le (le_trans this (nat.le_succ _))] },
have B : ∀ (j : fin n), ((j : ℕ) < i.succ) = ((j : ℕ) < i),
{ assume j,
have : (j : ℕ) < i := lt_of_lt_of_le j.2 (not_lt.mp h),
simp [this, lt_trans this (nat.lt_succ_self _)] },
simp [← A, B, IH] }
end
-- `to_additive` does not work on `prod_take_of_fn` because of `0 : ℕ` in the proof.
-- Use `multiplicative` instead.
lemma sum_take_of_fn [add_comm_monoid α] {n : ℕ} (f : fin n → α) (i : ℕ) :
((of_fn f).take i).sum = ∑ j in finset.univ.filter (λ (j : fin n), j.val < i), f j :=
@prod_take_of_fn (multiplicative α) _ n f i
attribute [to_additive] prod_take_of_fn
@[to_additive]
lemma prod_of_fn [comm_monoid α] {n : ℕ} {f : fin n → α} :
(of_fn f).prod = ∏ i, f i :=
begin
convert prod_take_of_fn f n,
{ rw [take_all_of_le (le_of_eq (length_of_fn f))] },
{ have : ∀ (j : fin n), (j : ℕ) < n := λ j, j.is_lt,
simp [this] }
end
lemma alternating_sum_eq_finset_sum {G : Type*} [add_comm_group G] :
∀ (L : list G), alternating_sum L = ∑ i : fin L.length, (-1 : ℤ) ^ (i : ℕ) • L.nth_le i i.is_lt
| [] := by { rw [alternating_sum, finset.sum_eq_zero], rintro ⟨i, ⟨⟩⟩ }
| (g :: []) :=
begin
show g = ∑ i : fin 1, (-1 : ℤ) ^ (i : ℕ) • [g].nth_le i i.2,
rw [fin.sum_univ_succ], simp,
end
| (g :: h :: L) :=
calc g + -h + L.alternating_sum
= g + -h + ∑ i : fin L.length, (-1 : ℤ) ^ (i : ℕ) • L.nth_le i i.2 :
congr_arg _ (alternating_sum_eq_finset_sum _)
... = ∑ i : fin (L.length + 2), (-1 : ℤ) ^ (i : ℕ) • list.nth_le (g :: h :: L) i _ :
begin
rw [fin.sum_univ_succ, fin.sum_univ_succ, add_assoc],
unfold_coes,
simp [nat.succ_eq_add_one, pow_add],
refl,
end
@[to_additive]
lemma alternating_prod_eq_finset_prod {G : Type*} [comm_group G] :
∀ (L : list G), alternating_prod L = ∏ i : fin L.length, (L.nth_le i i.2) ^ ((-1 : ℤ) ^ (i : ℕ))
| [] := by { rw [alternating_prod, finset.prod_eq_one], rintro ⟨i, ⟨⟩⟩ }
| (g :: []) :=
begin
show g = ∏ i : fin 1, [g].nth_le i i.2 ^ (-1 : ℤ) ^ (i : ℕ),
rw [fin.prod_univ_succ], simp,
end
| (g :: h :: L) :=
calc g * h⁻¹ * L.alternating_prod
= g * h⁻¹ * ∏ i : fin L.length, L.nth_le i i.2 ^ (-1 : ℤ) ^ (i : ℕ) :
congr_arg _ (alternating_prod_eq_finset_prod _)
... = ∏ i : fin (L.length + 2), list.nth_le (g :: h :: L) i _ ^ (-1 : ℤ) ^ (i : ℕ) :
begin
rw [fin.prod_univ_succ, fin.prod_univ_succ, mul_assoc],
unfold_coes,
simp [nat.succ_eq_add_one, pow_add],
refl,
end
end list
|
d32139da852742e26be95169938eccc996cce2e8 | 86f6f4f8d827a196a32bfc646234b73328aeb306 | /examples/logic/unnamed_323.lean | 6ac7f610729c92c5585e20a9e39180cb5639ac1c | [] | 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 | 126 | lean | import data.real.basic
-- BEGIN
example (f : ℝ → ℝ) (h : monotone f) :
∀ {a b}, a ≤ b → f a ≤ f b := h
-- END |
249ce02770c49b6494e4819f37cb8bd5c87d833a | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/measure_theory/bochner_integration.lean | dfee65b3c473350c63b19b86fe23135ddffb8b60 | [
"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 | 82,014 | lean | /-
Copyright (c) 2019 Zhouhang Zhou. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Zhouhang Zhou, Yury Kudryashov, Sébastien Gouëzel
-/
import measure_theory.simple_func_dense
import analysis.normed_space.bounded_linear_maps
import measure_theory.l1_space
import measure_theory.group
import topology.sequences
/-!
# Bochner integral
The Bochner integral extends the definition of the Lebesgue integral to functions that map from a
measure space into a Banach space (complete normed vector space). It is constructed here by
extending the integral on simple functions.
## Main definitions
The Bochner integral is defined following these steps:
1. Define the integral on simple functions of the type `simple_func α E` (notation : `α →ₛ E`)
where `E` is a real normed space.
(See `simple_func.bintegral` and section `bintegral` for details. Also see `simple_func.integral`
for the integral on simple functions of the type `simple_func α ℝ≥0∞`.)
2. Use `α →ₛ E` to cut out the simple functions from L1 functions, and define integral
on these. The type of simple functions in L1 space is written as `α →₁ₛ[μ] E`.
3. Show that the embedding of `α →₁ₛ[μ] E` into L1 is a dense and uniform one.
4. Show that the integral defined on `α →₁ₛ[μ] E` is a continuous linear map.
5. Define the Bochner integral on L1 functions by extending the integral on integrable simple
functions `α →₁ₛ[μ] E` using `continuous_linear_map.extend`. Define the Bochner integral on
functions as the Bochner integral of its equivalence class in L1 space.
## Main statements
1. Basic properties of the Bochner integral on functions of type `α → E`, where `α` is a measure
space and `E` is a real normed space.
* `integral_zero` : `∫ 0 ∂μ = 0`
* `integral_add` : `∫ x, f x + g x ∂μ = ∫ x, f ∂μ + ∫ x, g x ∂μ`
* `integral_neg` : `∫ x, - f x ∂μ = - ∫ x, f x ∂μ`
* `integral_sub` : `∫ x, f x - g x ∂μ = ∫ x, f x ∂μ - ∫ x, g x ∂μ`
* `integral_smul` : `∫ x, r • f x ∂μ = r • ∫ x, f x ∂μ`
* `integral_congr_ae` : `f =ᵐ[μ] g → ∫ x, f x ∂μ = ∫ x, g x ∂μ`
* `norm_integral_le_integral_norm` : `∥∫ x, f x ∂μ∥ ≤ ∫ x, ∥f x∥ ∂μ`
2. Basic properties of the Bochner integral on functions of type `α → ℝ`, where `α` is a measure
space.
* `integral_nonneg_of_ae` : `0 ≤ᵐ[μ] f → 0 ≤ ∫ x, f x ∂μ`
* `integral_nonpos_of_ae` : `f ≤ᵐ[μ] 0 → ∫ x, f x ∂μ ≤ 0`
* `integral_mono_ae` : `f ≤ᵐ[μ] g → ∫ x, f x ∂μ ≤ ∫ x, g x ∂μ`
* `integral_nonneg` : `0 ≤ f → 0 ≤ ∫ x, f x ∂μ`
* `integral_nonpos` : `f ≤ 0 → ∫ x, f x ∂μ ≤ 0`
* `integral_mono` : `f ≤ᵐ[μ] g → ∫ x, f x ∂μ ≤ ∫ x, g x ∂μ`
3. Propositions connecting the Bochner integral with the integral on `ℝ≥0∞`-valued functions,
which is called `lintegral` and has the notation `∫⁻`.
* `integral_eq_lintegral_max_sub_lintegral_min` : `∫ x, f x ∂μ = ∫⁻ x, f⁺ x ∂μ - ∫⁻ x, f⁻ x ∂μ`,
where `f⁺` is the positive part of `f` and `f⁻` is the negative part of `f`.
* `integral_eq_lintegral_of_nonneg_ae` : `0 ≤ᵐ[μ] f → ∫ x, f x ∂μ = ∫⁻ x, f x ∂μ`
4. `tendsto_integral_of_dominated_convergence` : the Lebesgue dominated convergence theorem
5. (In the file `set_integral`) integration commutes with continuous linear maps.
* `continuous_linear_map.integral_comp_comm`
* `linear_isometry.integral_comp_comm`
## Notes
Some tips on how to prove a proposition if the API for the Bochner integral is not enough so that
you need to unfold the definition of the Bochner integral and go back to simple functions.
One method is to use the theorem `integrable.induction` in the file `set_integral`, which allows
you to prove something for an arbitrary measurable + integrable function.
Another method is using the following steps.
See `integral_eq_lintegral_max_sub_lintegral_min` for a complicated example, which proves that
`∫ f = ∫⁻ f⁺ - ∫⁻ f⁻`, with the first integral sign being the Bochner integral of a real-valued
function `f : α → ℝ`, and second and third integral sign being the integral on `ℝ≥0∞`-valued
functions (called `lintegral`). The proof of `integral_eq_lintegral_max_sub_lintegral_min` is
scattered in sections with the name `pos_part`.
Here are the usual steps of proving that a property `p`, say `∫ f = ∫⁻ f⁺ - ∫⁻ f⁻`, holds for all
functions :
1. First go to the `L¹` space.
For example, if you see `ennreal.to_real (∫⁻ a, ennreal.of_real $ ∥f a∥)`, that is the norm of
`f` in `L¹` space. Rewrite using `L1.norm_of_fun_eq_lintegral_norm`.
2. Show that the set `{f ∈ L¹ | ∫ f = ∫⁻ f⁺ - ∫⁻ f⁻}` is closed in `L¹` using `is_closed_eq`.
3. Show that the property holds for all simple functions `s` in `L¹` space.
Typically, you need to convert various notions to their `simple_func` counterpart, using lemmas
like `L1.integral_coe_eq_integral`.
4. Since simple functions are dense in `L¹`,
```
univ = closure {s simple}
= closure {s simple | ∫ s = ∫⁻ s⁺ - ∫⁻ s⁻} : the property holds for all simple functions
⊆ closure {f | ∫ f = ∫⁻ f⁺ - ∫⁻ f⁻}
= {f | ∫ f = ∫⁻ f⁺ - ∫⁻ f⁻} : closure of a closed set is itself
```
Use `is_closed_property` or `dense_range.induction_on` for this argument.
## Notations
* `α →ₛ E` : simple functions (defined in `measure_theory/integration`)
* `α →₁[μ] E` : functions in L1 space, i.e., equivalence classes of integrable functions (defined in
`measure_theory/lp_space`)
* `α →₁ₛ[μ] E` : simple functions in L1 space, i.e., equivalence classes of integrable simple
functions
* `∫ a, f a ∂μ` : integral of `f` with respect to a measure `μ`
* `∫ a, f a` : integral of `f` with respect to `volume`, the default measure on the
ambient type
We also define notations for integral on a set, which are described in the file
`measure_theory/set_integral`.
Note : `ₛ` is typed using `\_s`. Sometimes it shows as a box if font is missing.
## Tags
Bochner integral, simple function, function space, Lebesgue dominated convergence theorem
-/
noncomputable theory
open_locale classical topological_space big_operators nnreal ennreal measure_theory
namespace measure_theory
variables {α E : Type*} [measurable_space α] [linear_order E] [has_zero E]
local infixr ` →ₛ `:25 := simple_func
namespace simple_func
section pos_part
/-- Positive part of a simple function. -/
def pos_part (f : α →ₛ E) : α →ₛ E := f.map (λb, max b 0)
/-- Negative part of a simple function. -/
def neg_part [has_neg E] (f : α →ₛ E) : α →ₛ E := pos_part (-f)
lemma pos_part_map_norm (f : α →ₛ ℝ) : (pos_part f).map norm = pos_part f :=
begin
ext,
rw [map_apply, real.norm_eq_abs, abs_of_nonneg],
rw [pos_part, map_apply],
exact le_max_right _ _
end
lemma neg_part_map_norm (f : α →ₛ ℝ) : (neg_part f).map norm = neg_part f :=
by { rw neg_part, exact pos_part_map_norm _ }
lemma pos_part_sub_neg_part (f : α →ₛ ℝ) : f.pos_part - f.neg_part = f :=
begin
simp only [pos_part, neg_part],
ext a,
rw coe_sub,
exact max_zero_sub_eq_self (f a)
end
end pos_part
end simple_func
end measure_theory
namespace measure_theory
open set filter topological_space ennreal emetric
variables {α E F 𝕜 : Type*} [measurable_space α]
local infixr ` →ₛ `:25 := simple_func
namespace simple_func
section integral
/-!
### The Bochner integral of simple functions
Define the Bochner integral of simple functions of the type `α →ₛ β` where `β` is a normed group,
and prove basic property of this integral.
-/
open finset
variables [normed_group E] [measurable_space E] [normed_group F]
variables {μ : measure α} {p : ℝ≥0∞}
/-!
#### Properties of simple functions
A simple function `f : α →ₛ E` into a normed group `E` verifies, for a measure `μ`:
- `mem_ℒp f 0 μ` and `mem_ℒp f ∞ μ`, since `f` is a.e.-measurable and bounded,
- for `0 < p < ∞`, `mem_ℒp f p μ ↔ integrable f μ ↔ f.fin_meas_supp μ ↔ ∀ y ≠ 0, μ (f ⁻¹' {y}) < ∞`.
-/
lemma exists_forall_norm_le (f : α →ₛ F) : ∃ C, ∀ x, ∥f x∥ ≤ C :=
exists_forall_le (f.map (λ x, ∥x∥))
lemma mem_ℒp_zero (f : α →ₛ E) (μ : measure α) : mem_ℒp f 0 μ :=
mem_ℒp_zero_iff_ae_measurable.mpr f.ae_measurable
lemma mem_ℒp_top (f : α →ₛ E) (μ : measure α) : mem_ℒp f ∞ μ :=
let ⟨C, hfC⟩ := f.exists_forall_norm_le in
mem_ℒp_top_of_bound f.ae_measurable C $ eventually_of_forall hfC
protected lemma snorm'_eq {p : ℝ} (f : α →ₛ F) (μ : measure α) :
snorm' f p μ = (∑ y in f.range, (nnnorm y : ℝ≥0∞) ^ p * μ (f ⁻¹' {y})) ^ (1/p) :=
have h_map : (λ a, (nnnorm (f a) : ℝ≥0∞) ^ p) = f.map (λ a : F, (nnnorm a : ℝ≥0∞) ^ p), by simp,
by rw [snorm', h_map, lintegral_eq_lintegral, map_lintegral]
lemma measure_preimage_lt_top_of_mem_ℒp (hp_pos : 0 < p) (hp_ne_top : p ≠ ∞) (f : α →ₛ E)
(hf : mem_ℒp f p μ) (y : E) (hy_ne : y ≠ 0) :
μ (f ⁻¹' {y}) < ∞ :=
begin
have hp_pos_real : 0 < p.to_real, from ennreal.to_real_pos_iff.mpr ⟨hp_pos, hp_ne_top⟩,
have hf_snorm := mem_ℒp.snorm_lt_top hf,
rw [snorm_eq_snorm' hp_pos.ne.symm hp_ne_top, f.snorm'_eq,
← @ennreal.lt_rpow_one_div_iff _ _ (1 / p.to_real) (by simp [hp_pos_real]),
@ennreal.top_rpow_of_pos (1 / (1 / p.to_real)) (by simp [hp_pos_real]),
ennreal.sum_lt_top_iff] at hf_snorm,
by_cases hyf : y ∈ f.range,
swap,
{ suffices h_empty : f ⁻¹' {y} = ∅,
by { rw [h_empty, measure_empty], exact ennreal.coe_lt_top, },
ext1 x,
rw [set.mem_preimage, set.mem_singleton_iff, mem_empty_eq, iff_false],
refine λ hxy, hyf _,
rw [mem_range, set.mem_range],
exact ⟨x, hxy⟩, },
specialize hf_snorm y hyf,
rw ennreal.mul_lt_top_iff at hf_snorm,
cases hf_snorm,
{ exact hf_snorm.2, },
cases hf_snorm,
{ refine absurd _ hy_ne,
simpa [hp_pos_real] using hf_snorm, },
{ simp [hf_snorm], },
end
lemma mem_ℒp_of_finite_measure_preimage (p : ℝ≥0∞) {f : α →ₛ E} (hf : ∀ y ≠ 0, μ (f ⁻¹' {y}) < ∞) :
mem_ℒp f p μ :=
begin
by_cases hp0 : p = 0,
{ rw [hp0, mem_ℒp_zero_iff_ae_measurable], exact f.ae_measurable, },
by_cases hp_top : p = ∞,
{ rw hp_top, exact mem_ℒp_top f μ, },
refine ⟨f.ae_measurable, _⟩,
rw [snorm_eq_snorm' hp0 hp_top, f.snorm'_eq],
refine ennreal.rpow_lt_top_of_nonneg (by simp) (ennreal.sum_lt_top_iff.mpr (λ y hy, _)).ne,
by_cases hy0 : y = 0,
{ simp [hy0, ennreal.to_real_pos_iff.mpr ⟨lt_of_le_of_ne (zero_le _) (ne.symm hp0), hp_top⟩], },
{ refine ennreal.mul_lt_top _ (hf y hy0),
exact ennreal.rpow_lt_top_of_nonneg ennreal.to_real_nonneg ennreal.coe_ne_top, },
end
lemma mem_ℒp_iff {f : α →ₛ E} (hp_pos : 0 < p) (hp_ne_top : p ≠ ∞) :
mem_ℒp f p μ ↔ ∀ y ≠ 0, μ (f ⁻¹' {y}) < ∞ :=
⟨λ h, measure_preimage_lt_top_of_mem_ℒp hp_pos hp_ne_top f h,
λ h, mem_ℒp_of_finite_measure_preimage p h⟩
lemma integrable_iff {f : α →ₛ E} : integrable f μ ↔ ∀ y ≠ 0, μ (f ⁻¹' {y}) < ∞ :=
mem_ℒp_one_iff_integrable.symm.trans $ mem_ℒp_iff ennreal.zero_lt_one ennreal.coe_ne_top
lemma mem_ℒp_iff_integrable {f : α →ₛ E} (hp_pos : 0 < p) (hp_ne_top : p ≠ ∞) :
mem_ℒp f p μ ↔ integrable f μ :=
(mem_ℒp_iff hp_pos hp_ne_top).trans integrable_iff.symm
lemma mem_ℒp_iff_fin_meas_supp {f : α →ₛ E} (hp_pos : 0 < p) (hp_ne_top : p ≠ ∞) :
mem_ℒp f p μ ↔ f.fin_meas_supp μ :=
(mem_ℒp_iff hp_pos hp_ne_top).trans fin_meas_supp_iff.symm
lemma integrable_iff_fin_meas_supp {f : α →ₛ E} : integrable f μ ↔ f.fin_meas_supp μ :=
integrable_iff.trans fin_meas_supp_iff.symm
lemma fin_meas_supp.integrable {f : α →ₛ E} (h : f.fin_meas_supp μ) : integrable f μ :=
integrable_iff_fin_meas_supp.2 h
lemma integrable_pair [measurable_space F] {f : α →ₛ E} {g : α →ₛ F} :
integrable f μ → integrable g μ → integrable (pair f g) μ :=
by simpa only [integrable_iff_fin_meas_supp] using fin_meas_supp.pair
lemma mem_ℒp_of_finite_measure (f : α →ₛ E) (p : ℝ≥0∞) (μ : measure α) [finite_measure μ] :
mem_ℒp f p μ :=
let ⟨C, hfC⟩ := f.exists_forall_norm_le in
mem_ℒp.of_bound f.ae_measurable C $ eventually_of_forall hfC
lemma integrable_of_finite_measure [finite_measure μ] (f : α →ₛ E) : integrable f μ :=
mem_ℒp_one_iff_integrable.mp (f.mem_ℒp_of_finite_measure 1 μ)
lemma measure_preimage_lt_top_of_integrable (f : α →ₛ E) (hf : integrable f μ) {x : E}
(hx : x ≠ 0) :
μ (f ⁻¹' {x}) < ∞ :=
integrable_iff.mp hf x hx
variables [normed_space ℝ F]
/-- Bochner integral of simple functions whose codomain is a real `normed_space`. -/
def integral (μ : measure α) (f : α →ₛ F) : F :=
∑ x in f.range, (ennreal.to_real (μ (f ⁻¹' {x}))) • x
lemma integral_eq_sum_filter (f : α →ₛ F) (μ) :
f.integral μ = ∑ x in f.range.filter (λ x, x ≠ 0), (ennreal.to_real (μ (f ⁻¹' {x}))) • x :=
eq.symm $ sum_filter_of_ne $ λ x _, mt $ λ h0, h0.symm ▸ smul_zero _
/-- The Bochner integral is equal to a sum over any set that includes `f.range` (except `0`). -/
lemma integral_eq_sum_of_subset {f : α →ₛ F} {μ : measure α} {s : finset F}
(hs : f.range.filter (λ x, x ≠ 0) ⊆ s) : f.integral μ = ∑ x in s, (μ (f ⁻¹' {x})).to_real • x :=
begin
rw [simple_func.integral_eq_sum_filter, finset.sum_subset hs],
rintro x - hx, rw [finset.mem_filter, not_and_distrib, ne.def, not_not] at hx,
rcases hx with hx|rfl; [skip, simp],
rw [simple_func.mem_range] at hx, rw [preimage_eq_empty]; simp [disjoint_singleton_left, hx]
end
/-- Calculate the integral of `g ∘ f : α →ₛ F`, where `f` is an integrable function from `α` to `E`
and `g` is a function from `E` to `F`. We require `g 0 = 0` so that `g ∘ f` is integrable. -/
lemma map_integral (f : α →ₛ E) (g : E → F) (hf : integrable f μ) (hg : g 0 = 0) :
(f.map g).integral μ = ∑ x in f.range, (ennreal.to_real (μ (f ⁻¹' {x}))) • (g x) :=
begin
-- We start as in the proof of `map_lintegral`
simp only [integral, range_map],
refine finset.sum_image' _ (assume b hb, _),
rcases mem_range.1 hb with ⟨a, rfl⟩,
rw [map_preimage_singleton, ← sum_measure_preimage_singleton _
(λ _ _, f.measurable_set_preimage _)],
-- Now we use `hf : integrable f μ` to show that `ennreal.to_real` is additive.
by_cases ha : g (f a) = 0,
{ simp only [ha, smul_zero],
refine (sum_eq_zero $ λ x hx, _).symm,
simp only [mem_filter] at hx,
simp [hx.2] },
{ rw [to_real_sum, sum_smul],
{ refine sum_congr rfl (λ x hx, _),
simp only [mem_filter] at hx,
rw [hx.2] },
{ intros x hx,
simp only [mem_filter] at hx,
refine (integrable_iff_fin_meas_supp.1 hf).meas_preimage_singleton_ne_zero _,
exact λ h0, ha (hx.2 ▸ h0.symm ▸ hg) } },
end
/-- `simple_func.integral` and `simple_func.lintegral` agree when the integrand has type
`α →ₛ ℝ≥0∞`. But since `ℝ≥0∞` is not a `normed_space`, we need some form of coercion.
See `integral_eq_lintegral` for a simpler version. -/
lemma integral_eq_lintegral' {f : α →ₛ E} {g : E → ℝ≥0∞} (hf : integrable f μ) (hg0 : g 0 = 0)
(hgt : ∀b, g b < ∞):
(f.map (ennreal.to_real ∘ g)).integral μ = ennreal.to_real (∫⁻ a, g (f a) ∂μ) :=
begin
have hf' : f.fin_meas_supp μ := integrable_iff_fin_meas_supp.1 hf,
simp only [← map_apply g f, lintegral_eq_lintegral],
rw [map_integral f _ hf, map_lintegral, ennreal.to_real_sum],
{ refine finset.sum_congr rfl (λb hb, _),
rw [smul_eq_mul, to_real_mul, mul_comm] },
{ assume a ha,
by_cases a0 : a = 0,
{ rw [a0, hg0, zero_mul], exact with_top.zero_lt_top },
{ apply mul_lt_top (hgt a) (hf'.meas_preimage_singleton_ne_zero a0) } },
{ simp [hg0] }
end
variables [normed_field 𝕜] [normed_space 𝕜 E] [normed_space ℝ E]
[smul_comm_class ℝ 𝕜 E]
lemma integral_congr {f g : α →ₛ E} (hf : integrable f μ) (h : f =ᵐ[μ] g):
f.integral μ = g.integral μ :=
show ((pair f g).map prod.fst).integral μ = ((pair f g).map prod.snd).integral μ, from
begin
have inte := integrable_pair hf (hf.congr h),
rw [map_integral (pair f g) _ inte prod.fst_zero, map_integral (pair f g) _ inte prod.snd_zero],
refine finset.sum_congr rfl (assume p hp, _),
rcases mem_range.1 hp with ⟨a, rfl⟩,
by_cases eq : f a = g a,
{ dsimp only [pair_apply], rw eq },
{ have : μ ((pair f g) ⁻¹' {(f a, g a)}) = 0,
{ refine measure_mono_null (assume a' ha', _) h,
simp only [set.mem_preimage, mem_singleton_iff, pair_apply, prod.mk.inj_iff] at ha',
show f a' ≠ g a',
rwa [ha'.1, ha'.2] },
simp only [this, pair_apply, zero_smul, ennreal.zero_to_real] },
end
/-- `simple_func.bintegral` and `simple_func.integral` agree when the integrand has type
`α →ₛ ℝ≥0∞`. But since `ℝ≥0∞` is not a `normed_space`, we need some form of coercion. -/
lemma integral_eq_lintegral {f : α →ₛ ℝ} (hf : integrable f μ) (h_pos : 0 ≤ᵐ[μ] f) :
f.integral μ = ennreal.to_real (∫⁻ a, ennreal.of_real (f a) ∂μ) :=
begin
have : f =ᵐ[μ] f.map (ennreal.to_real ∘ ennreal.of_real) :=
h_pos.mono (λ a h, (ennreal.to_real_of_real h).symm),
rw [← integral_eq_lintegral' hf],
{ exact integral_congr hf this },
{ exact ennreal.of_real_zero },
{ assume b, rw ennreal.lt_top_iff_ne_top, exact ennreal.of_real_ne_top }
end
lemma integral_add {f g : α →ₛ E} (hf : integrable f μ) (hg : integrable g μ) :
integral μ (f + g) = integral μ f + integral μ g :=
calc integral μ (f + g) = ∑ x in (pair f g).range,
ennreal.to_real (μ ((pair f g) ⁻¹' {x})) • (x.fst + x.snd) :
begin
rw [add_eq_map₂, map_integral (pair f g)],
{ exact integrable_pair hf hg },
{ simp only [add_zero, prod.fst_zero, prod.snd_zero] }
end
... = ∑ x in (pair f g).range,
(ennreal.to_real (μ ((pair f g) ⁻¹' {x})) • x.fst +
ennreal.to_real (μ ((pair f g) ⁻¹' {x})) • x.snd) :
finset.sum_congr rfl $ assume a ha, smul_add _ _ _
... = ∑ x in (pair f g).range,
ennreal.to_real (μ ((pair f g) ⁻¹' {x})) • x.fst +
∑ x in (pair f g).range,
ennreal.to_real (μ ((pair f g) ⁻¹' {x})) • x.snd :
by rw finset.sum_add_distrib
... = ((pair f g).map prod.fst).integral μ + ((pair f g).map prod.snd).integral μ :
begin
rw [map_integral (pair f g), map_integral (pair f g)],
{ exact integrable_pair hf hg }, { refl },
{ exact integrable_pair hf hg }, { refl }
end
... = integral μ f + integral μ g : rfl
lemma integral_neg {f : α →ₛ E} (hf : integrable f μ) : integral μ (-f) = - integral μ f :=
calc integral μ (-f) = integral μ (f.map (has_neg.neg)) : rfl
... = - integral μ f :
begin
rw [map_integral f _ hf neg_zero, integral, ← sum_neg_distrib],
refine finset.sum_congr rfl (λx h, smul_neg _ _),
end
lemma integral_sub [borel_space E] {f g : α →ₛ E} (hf : integrable f μ) (hg : integrable g μ) :
integral μ (f - g) = integral μ f - integral μ g :=
begin
rw [sub_eq_add_neg, integral_add hf, integral_neg hg, sub_eq_add_neg],
exact hg.neg
end
lemma integral_smul (c : 𝕜) {f : α →ₛ E} (hf : integrable f μ) :
integral μ (c • f) = c • integral μ f :=
calc integral μ (c • f) = ∑ x in f.range, ennreal.to_real (μ (f ⁻¹' {x})) • c • x :
by rw [smul_eq_map c f, map_integral f _ hf (smul_zero _)]
... = ∑ x in f.range, c • (ennreal.to_real (μ (f ⁻¹' {x}))) • x :
finset.sum_congr rfl $ λ b hb, by { exact smul_comm _ _ _}
... = c • integral μ f :
by simp only [integral, smul_sum, smul_smul, mul_comm]
lemma norm_integral_le_integral_norm (f : α →ₛ E) (hf : integrable f μ) :
∥f.integral μ∥ ≤ (f.map norm).integral μ :=
begin
rw [map_integral f norm hf norm_zero, integral],
calc ∥∑ x in f.range, ennreal.to_real (μ (f ⁻¹' {x})) • x∥ ≤
∑ x in f.range, ∥ennreal.to_real (μ (f ⁻¹' {x})) • x∥ :
norm_sum_le _ _
... = ∑ x in f.range, ennreal.to_real (μ (f ⁻¹' {x})) • ∥x∥ :
begin
refine finset.sum_congr rfl (λb hb, _),
rw [norm_smul, smul_eq_mul, real.norm_eq_abs, abs_of_nonneg to_real_nonneg]
end
end
lemma integral_add_measure {ν} (f : α →ₛ E) (hf : integrable f (μ + ν)) :
f.integral (μ + ν) = f.integral μ + f.integral ν :=
begin
simp only [integral_eq_sum_filter, ← sum_add_distrib, ← add_smul, measure.add_apply],
refine sum_congr rfl (λ x hx, _),
rw [to_real_add];
refine ne_of_lt ((integrable_iff_fin_meas_supp.1 _).meas_preimage_singleton_ne_zero
(mem_filter.1 hx).2),
exacts [hf.left_of_add_measure, hf.right_of_add_measure]
end
end integral
end simple_func
namespace L1
open ae_eq_fun
variables
[normed_group E] [second_countable_topology E] [measurable_space E] [borel_space E]
[normed_group F] [second_countable_topology F] [measurable_space F] [borel_space F]
{μ : measure α}
variables (α E μ)
/-- `L1.simple_func` is a subspace of L1 consisting of equivalence classes of an integrable simple
function. -/
def simple_func : add_subgroup (Lp E 1 μ) :=
{ carrier := {f : α →₁[μ] E | ∃ (s : α →ₛ E), (ae_eq_fun.mk s s.ae_measurable : α →ₘ[μ] E) = f},
zero_mem' := ⟨0, rfl⟩,
add_mem' := λ f g ⟨s, hs⟩ ⟨t, ht⟩, ⟨s + t,
by simp only [←hs, ←ht, mk_add_mk, add_subgroup.coe_add, mk_eq_mk, simple_func.coe_add]⟩,
neg_mem' := λ f ⟨s, hs⟩, ⟨-s,
by simp only [←hs, neg_mk, simple_func.coe_neg, mk_eq_mk, add_subgroup.coe_neg]⟩ }
variables {α E μ}
notation α ` →₁ₛ[`:25 μ `] ` E := measure_theory.L1.simple_func α E μ
namespace simple_func
section instances
/-! Simple functions in L1 space form a `normed_space`. -/
instance : has_coe (α →₁ₛ[μ] E) (α →₁[μ] E) := coe_subtype
instance : has_coe_to_fun (α →₁ₛ[μ] E) := ⟨λ f, α → E, λ f, ⇑(f : α →₁[μ] E)⟩
@[simp, norm_cast] lemma coe_coe (f : α →₁ₛ[μ] E) : ⇑(f : α →₁[μ] E) = f := rfl
protected lemma eq {f g : α →₁ₛ[μ] E} : (f : α →₁[μ] E) = (g : α →₁[μ] E) → f = g := subtype.eq
protected lemma eq' {f g : α →₁ₛ[μ] E} : (f : α →ₘ[μ] E) = (g : α →ₘ[μ] E) → f = g :=
subtype.eq ∘ subtype.eq
@[norm_cast] protected lemma eq_iff {f g : α →₁ₛ[μ] E} : (f : α →₁[μ] E) = g ↔ f = g :=
subtype.ext_iff.symm
@[norm_cast] protected lemma eq_iff' {f g : α →₁ₛ[μ] E} : (f : α →ₘ[μ] E) = g ↔ f = g :=
iff.intro (simple_func.eq') (congr_arg _)
/-- L1 simple functions forms a `normed_group`, with the metric being inherited from L1 space,
i.e., `dist f g = ennreal.to_real (∫⁻ a, edist (f a) (g a)`).
Not declared as an instance as `α →₁ₛ[μ] β` will only be useful in the construction of the Bochner
integral. -/
protected def normed_group : normed_group (α →₁ₛ[μ] E) := by apply_instance
local attribute [instance] simple_func.normed_group
/-- Functions `α →₁ₛ[μ] E` form an additive commutative group. -/
instance : inhabited (α →₁ₛ[μ] E) := ⟨0⟩
@[simp, norm_cast]
lemma coe_zero : ((0 : α →₁ₛ[μ] E) : α →₁[μ] E) = 0 := rfl
@[simp, norm_cast]
lemma coe_add (f g : α →₁ₛ[μ] E) : ((f + g : α →₁ₛ[μ] E) : α →₁[μ] E) = f + g := rfl
@[simp, norm_cast]
lemma coe_neg (f : α →₁ₛ[μ] E) : ((-f : α →₁ₛ[μ] E) : α →₁[μ] E) = -f := rfl
@[simp, norm_cast]
lemma coe_sub (f g : α →₁ₛ[μ] E) : ((f - g : α →₁ₛ[μ] E) : α →₁[μ] E) = f - g := rfl
@[simp] lemma edist_eq (f g : α →₁ₛ[μ] E) : edist f g = edist (f : α →₁[μ] E) (g : α →₁[μ] E) := rfl
@[simp] lemma dist_eq (f g : α →₁ₛ[μ] E) : dist f g = dist (f : α →₁[μ] E) (g : α →₁[μ] E) := rfl
lemma norm_eq (f : α →₁ₛ[μ] E) : ∥f∥ = ∥(f : α →₁[μ] E)∥ := rfl
variables [normed_field 𝕜] [normed_space 𝕜 E] [measurable_space 𝕜] [opens_measurable_space 𝕜]
/-- Not declared as an instance as `α →₁ₛ[μ] E` will only be useful in the construction of the
Bochner integral. -/
protected def has_scalar : has_scalar 𝕜 (α →₁ₛ[μ] E) := ⟨λk f, ⟨k • f,
begin
rcases f with ⟨f, ⟨s, hs⟩⟩,
use k • s,
apply eq.trans (smul_mk k s s.ae_measurable).symm _,
rw hs,
refl,
end ⟩⟩
local attribute [instance, priority 10000] simple_func.has_scalar
@[simp, norm_cast] lemma coe_smul (c : 𝕜) (f : α →₁ₛ[μ] E) :
((c • f : α →₁ₛ[μ] E) : α →₁[μ] E) = c • (f : α →₁[μ] E) := rfl
/-- Not declared as an instance as `α →₁ₛ[μ] E` will only be useful in the construction of the
Bochner integral. -/
protected def module : module 𝕜 (α →₁ₛ[μ] E) :=
{ one_smul := λf, simple_func.eq (by { simp only [coe_smul], exact one_smul _ _ }),
mul_smul := λx y f, simple_func.eq (by { simp only [coe_smul], exact mul_smul _ _ _ }),
smul_add := λx f g, simple_func.eq (by { simp only [coe_smul], exact smul_add _ _ _ }),
smul_zero := λx, simple_func.eq (by { simp only [coe_smul], exact smul_zero _ }),
add_smul := λx y f, simple_func.eq (by { simp only [coe_smul], exact add_smul _ _ _ }),
zero_smul := λf, simple_func.eq (by { simp only [coe_smul], exact zero_smul _ _ }) }
local attribute [instance] simple_func.normed_group simple_func.module
/-- Not declared as an instance as `α →₁ₛ[μ] E` will only be useful in the construction of the
Bochner integral. -/
protected def normed_space : normed_space 𝕜 (α →₁ₛ[μ] E) :=
⟨ λc f, by { rw [norm_eq, norm_eq, coe_smul, norm_smul] } ⟩
end instances
local attribute [instance] simple_func.normed_group simple_func.normed_space
section to_L1
/-- Construct the equivalence class `[f]` of an integrable simple function `f`. -/
@[reducible] def to_L1 (f : α →ₛ E) (hf : integrable f μ) : (α →₁ₛ[μ] E) :=
⟨hf.to_L1 f, ⟨f, rfl⟩⟩
lemma to_L1_eq_to_L1 (f : α →ₛ E) (hf : integrable f μ) :
(to_L1 f hf : α →₁[μ] E) = hf.to_L1 f := rfl
lemma to_L1_eq_mk (f : α →ₛ E) (hf : integrable f μ) :
(to_L1 f hf : α →ₘ[μ] E) = ae_eq_fun.mk f f.ae_measurable := rfl
lemma to_L1_zero : to_L1 (0 : α →ₛ E) (integrable_zero α E μ) = 0 := rfl
lemma to_L1_add (f g : α →ₛ E) (hf : integrable f μ) (hg : integrable g μ) :
to_L1 (f + g) (hf.add hg) = to_L1 f hf + to_L1 g hg := rfl
lemma to_L1_neg (f : α →ₛ E) (hf : integrable f μ) :
to_L1 (-f) hf.neg = -to_L1 f hf := rfl
lemma to_L1_sub (f g : α →ₛ E) (hf : integrable f μ) (hg : integrable g μ) :
to_L1 (f - g) (hf.sub hg) = to_L1 f hf - to_L1 g hg :=
by { simp only [sub_eq_add_neg, ← to_L1_neg, ← to_L1_add], refl }
variables [normed_field 𝕜] [normed_space 𝕜 E] [measurable_space 𝕜] [opens_measurable_space 𝕜]
lemma to_L1_smul (f : α →ₛ E) (hf : integrable f μ) (c : 𝕜) :
to_L1 (c • f) (hf.smul c) = c • to_L1 f hf := rfl
lemma norm_to_L1 (f : α →ₛ E) (hf : integrable f μ) :
∥to_L1 f hf∥ = ennreal.to_real (∫⁻ a, edist (f a) 0 ∂μ) :=
by simp [to_L1, integrable.norm_to_L1]
end to_L1
section to_simple_func
/-- Find a representative of a `L1.simple_func`. -/
def to_simple_func (f : α →₁ₛ[μ] E) : α →ₛ E := classical.some f.2
/-- `(to_simple_func f)` is measurable. -/
@[measurability]
protected lemma measurable (f : α →₁ₛ[μ] E) : measurable (to_simple_func f) :=
(to_simple_func f).measurable
@[measurability]
protected lemma ae_measurable (f : α →₁ₛ[μ] E) : ae_measurable (to_simple_func f) μ :=
(simple_func.measurable f).ae_measurable
/-- `to_simple_func f` is integrable. -/
protected lemma integrable (f : α →₁ₛ[μ] E) : integrable (to_simple_func f) μ :=
begin
apply (integrable_mk (simple_func.ae_measurable f)).1,
convert integrable_coe_fn f.val,
exact classical.some_spec f.2
end
lemma to_L1_to_simple_func (f : α →₁ₛ[μ] E) :
to_L1 (to_simple_func f) (simple_func.integrable f) = f :=
by { rw ← simple_func.eq_iff', exact classical.some_spec f.2 }
lemma to_simple_func_to_L1 (f : α →ₛ E) (hfi : integrable f μ) :
to_simple_func (to_L1 f hfi) =ᵐ[μ] f :=
by { rw ← mk_eq_mk, exact classical.some_spec (to_L1 f hfi).2 }
lemma to_simple_func_eq_to_fun (f : α →₁ₛ[μ] E) : to_simple_func f =ᵐ[μ] f :=
begin
simp_rw [← integrable.to_L1_eq_to_L1_iff (to_simple_func f) f (simple_func.integrable f)
(integrable_coe_fn ↑f), subtype.ext_iff],
convert classical.some_spec f.coe_prop,
exact integrable.to_L1_coe_fn _ _,
end
variables (E μ)
lemma zero_to_simple_func : to_simple_func (0 : α →₁ₛ[μ] E) =ᵐ[μ] 0 :=
begin
filter_upwards [to_simple_func_eq_to_fun (0 : α →₁ₛ[μ] E), Lp.coe_fn_zero E 1 μ],
assume a h₁ h₂,
rwa h₁,
end
variables {E μ}
lemma add_to_simple_func (f g : α →₁ₛ[μ] E) :
to_simple_func (f + g) =ᵐ[μ] to_simple_func f + to_simple_func g :=
begin
filter_upwards [to_simple_func_eq_to_fun (f + g), to_simple_func_eq_to_fun f,
to_simple_func_eq_to_fun g, Lp.coe_fn_add (f : α →₁[μ] E) g],
assume a,
simp only [← coe_coe, coe_add, pi.add_apply],
iterate 4 { assume h, rw h }
end
lemma neg_to_simple_func (f : α →₁ₛ[μ] E) : to_simple_func (-f) =ᵐ[μ] - to_simple_func f :=
begin
filter_upwards [to_simple_func_eq_to_fun (-f), to_simple_func_eq_to_fun f,
Lp.coe_fn_neg (f : α →₁[μ] E)],
assume a,
simp only [pi.neg_apply, coe_neg, ← coe_coe],
repeat { assume h, rw h }
end
lemma sub_to_simple_func (f g : α →₁ₛ[μ] E) :
to_simple_func (f - g) =ᵐ[μ] to_simple_func f - to_simple_func g :=
begin
filter_upwards [to_simple_func_eq_to_fun (f - g), to_simple_func_eq_to_fun f,
to_simple_func_eq_to_fun g, Lp.coe_fn_sub (f : α →₁[μ] E) g],
assume a,
simp only [coe_sub, pi.sub_apply, ← coe_coe],
repeat { assume h, rw h }
end
variables [normed_field 𝕜] [normed_space 𝕜 E] [measurable_space 𝕜] [opens_measurable_space 𝕜]
lemma smul_to_simple_func (k : 𝕜) (f : α →₁ₛ[μ] E) :
to_simple_func (k • f) =ᵐ[μ] k • to_simple_func f :=
begin
filter_upwards [to_simple_func_eq_to_fun (k • f), to_simple_func_eq_to_fun f,
Lp.coe_fn_smul k (f : α →₁[μ] E)],
assume a,
simp only [pi.smul_apply, coe_smul, ← coe_coe],
repeat { assume h, rw h }
end
lemma lintegral_edist_to_simple_func_lt_top (f g : α →₁ₛ[μ] E) :
∫⁻ (x : α), edist (to_simple_func f x) (to_simple_func g x) ∂μ < ∞ :=
begin
rw lintegral_rw₂ (to_simple_func_eq_to_fun f) (to_simple_func_eq_to_fun g),
exact lintegral_edist_lt_top (integrable_coe_fn _) (integrable_coe_fn _)
end
lemma dist_to_simple_func (f g : α →₁ₛ[μ] E) : dist f g =
ennreal.to_real (∫⁻ x, edist (to_simple_func f x) (to_simple_func g x) ∂μ) :=
begin
rw [dist_eq, L1.dist_def, ennreal.to_real_eq_to_real],
{ rw lintegral_rw₂, repeat { exact ae_eq_symm (to_simple_func_eq_to_fun _) } },
{ exact lintegral_edist_lt_top (integrable_coe_fn _) (integrable_coe_fn _) },
{ exact lintegral_edist_to_simple_func_lt_top _ _ }
end
lemma norm_to_simple_func (f : α →₁ₛ[μ] E) :
∥f∥ = ennreal.to_real (∫⁻ (a : α), nnnorm ((to_simple_func f) a) ∂μ) :=
calc ∥f∥ =
ennreal.to_real (∫⁻x, edist ((to_simple_func f) x) (to_simple_func (0 : α →₁ₛ[μ] E) x) ∂μ) :
begin
rw [← dist_zero_right, dist_to_simple_func]
end
... = ennreal.to_real (∫⁻ (x : α), (coe ∘ nnnorm) ((to_simple_func f) x) ∂μ) :
begin
rw lintegral_nnnorm_eq_lintegral_edist,
have : ∫⁻ x, edist ((to_simple_func f) x) ((to_simple_func (0 : α →₁ₛ[μ] E)) x) ∂μ =
∫⁻ x, edist ((to_simple_func f) x) 0 ∂μ,
{ refine lintegral_congr_ae ((zero_to_simple_func E μ).mono (λ a h, _)),
rw [h, pi.zero_apply] },
rw [ennreal.to_real_eq_to_real],
{ exact this },
{ exact lintegral_edist_to_simple_func_lt_top _ _ },
{ rw ← this, exact lintegral_edist_to_simple_func_lt_top _ _ }
end
lemma norm_eq_integral (f : α →₁ₛ[μ] E) : ∥f∥ = ((to_simple_func f).map norm).integral μ :=
begin
rw [norm_to_simple_func, simple_func.integral_eq_lintegral],
{ simp only [simple_func.map_apply, of_real_norm_eq_coe_nnnorm] },
{ exact (simple_func.integrable f).norm },
{ exact eventually_of_forall (λ x, norm_nonneg _) }
end
end to_simple_func
section coe_to_L1
protected lemma uniform_continuous : uniform_continuous (coe : (α →₁ₛ[μ] E) → (α →₁[μ] E)) :=
uniform_continuous_comap
protected lemma uniform_embedding : uniform_embedding (coe : (α →₁ₛ[μ] E) → (α →₁[μ] E)) :=
uniform_embedding_comap subtype.val_injective
protected lemma uniform_inducing : uniform_inducing (coe : (α →₁ₛ[μ] E) → (α →₁[μ] E)) :=
simple_func.uniform_embedding.to_uniform_inducing
protected lemma dense_embedding : dense_embedding (coe : (α →₁ₛ[μ] E) → (α →₁[μ] E)) :=
begin
apply simple_func.uniform_embedding.dense_embedding,
assume f,
rw mem_closure_iff_seq_limit,
have hfi' : integrable f μ := integrable_coe_fn f,
refine ⟨λ n, ↑(to_L1 (simple_func.approx_on f (Lp.measurable f) univ 0 trivial n)
(simple_func.integrable_approx_on_univ (Lp.measurable f) hfi' n)), λ n, mem_range_self _, _⟩,
convert simple_func.tendsto_approx_on_univ_L1 (Lp.measurable f) hfi',
rw integrable.to_L1_coe_fn
end
protected lemma dense_inducing : dense_inducing (coe : (α →₁ₛ[μ] E) → (α →₁[μ] E)) :=
simple_func.dense_embedding.to_dense_inducing
protected lemma dense_range : dense_range (coe : (α →₁ₛ[μ] E) → (α →₁[μ] E)) :=
simple_func.dense_inducing.dense
variables [normed_field 𝕜] [normed_space 𝕜 E] [measurable_space 𝕜] [opens_measurable_space 𝕜]
variables (α E 𝕜)
/-- The uniform and dense embedding of L1 simple functions into L1 functions. -/
def coe_to_L1 : (α →₁ₛ[μ] E) →L[𝕜] (α →₁[μ] E) :=
{ to_fun := (coe : (α →₁ₛ[μ] E) → (α →₁[μ] E)),
map_add' := λf g, rfl,
map_smul' := λk f, rfl,
cont := L1.simple_func.uniform_continuous.continuous, }
variables {α E 𝕜}
end coe_to_L1
section pos_part
/-- Positive part of a simple function in L1 space. -/
def pos_part (f : α →₁ₛ[μ] ℝ) : α →₁ₛ[μ] ℝ := ⟨Lp.pos_part (f : α →₁[μ] ℝ),
begin
rcases f with ⟨f, s, hsf⟩,
use s.pos_part,
simp only [subtype.coe_mk, Lp.coe_pos_part, ← hsf, ae_eq_fun.pos_part_mk, simple_func.pos_part,
simple_func.coe_map]
end ⟩
/-- Negative part of a simple function in L1 space. -/
def neg_part (f : α →₁ₛ[μ] ℝ) : α →₁ₛ[μ] ℝ := pos_part (-f)
@[norm_cast]
lemma coe_pos_part (f : α →₁ₛ[μ] ℝ) : (pos_part f : α →₁[μ] ℝ) = Lp.pos_part (f : α →₁[μ] ℝ) := rfl
@[norm_cast]
lemma coe_neg_part (f : α →₁ₛ[μ] ℝ) : (neg_part f : α →₁[μ] ℝ) = Lp.neg_part (f : α →₁[μ] ℝ) := rfl
end pos_part
section simple_func_integral
/-! Define the Bochner integral on `α →₁ₛ[μ] E` and prove basic properties of this integral. -/
variables [normed_field 𝕜] [normed_space 𝕜 E] [normed_space ℝ E] [smul_comm_class ℝ 𝕜 E]
/-- The Bochner integral over simple functions in L1 space. -/
def integral (f : α →₁ₛ[μ] E) : E := ((to_simple_func f)).integral μ
lemma integral_eq_integral (f : α →₁ₛ[μ] E) : integral f = ((to_simple_func f)).integral μ := rfl
lemma integral_eq_lintegral {f : α →₁ₛ[μ] ℝ} (h_pos : 0 ≤ᵐ[μ] (to_simple_func f)) :
integral f = ennreal.to_real (∫⁻ a, ennreal.of_real ((to_simple_func f) a) ∂μ) :=
by rw [integral, simple_func.integral_eq_lintegral (simple_func.integrable f) h_pos]
lemma integral_congr {f g : α →₁ₛ[μ] E} (h : to_simple_func f =ᵐ[μ] to_simple_func g) :
integral f = integral g :=
simple_func.integral_congr (simple_func.integrable f) h
lemma integral_add (f g : α →₁ₛ[μ] E) : integral (f + g) = integral f + integral g :=
begin
simp only [integral],
rw ← simple_func.integral_add (simple_func.integrable f) (simple_func.integrable g),
apply measure_theory.simple_func.integral_congr (simple_func.integrable (f + g)),
apply add_to_simple_func
end
lemma integral_smul [measurable_space 𝕜] [opens_measurable_space 𝕜] (c : 𝕜) (f : α →₁ₛ[μ] E) :
integral (c • f) = c • integral f :=
begin
simp only [integral],
rw ← simple_func.integral_smul _ (simple_func.integrable f),
apply measure_theory.simple_func.integral_congr (simple_func.integrable (c • f)),
apply smul_to_simple_func,
repeat { assumption },
end
lemma norm_integral_le_norm (f : α →₁ₛ[μ] E) : ∥integral f∥ ≤ ∥f∥ :=
begin
rw [integral, norm_eq_integral],
exact (to_simple_func f).norm_integral_le_integral_norm (simple_func.integrable f)
end
variables (α E μ 𝕜) [measurable_space 𝕜] [opens_measurable_space 𝕜]
/-- The Bochner integral over simple functions in L1 space as a continuous linear map. -/
def integral_clm' : (α →₁ₛ[μ] E) →L[𝕜] E :=
linear_map.mk_continuous ⟨integral, integral_add, integral_smul⟩
1 (λf, le_trans (norm_integral_le_norm _) $ by rw one_mul)
/-- The Bochner integral over simple functions in L1 space as a continuous linear map over ℝ. -/
def integral_clm : (α →₁ₛ[μ] E) →L[ℝ] E := integral_clm' α E ℝ μ
variables {α E μ 𝕜}
local notation `Integral` := integral_clm α E μ
open continuous_linear_map
lemma norm_Integral_le_one : ∥Integral∥ ≤ 1 :=
linear_map.mk_continuous_norm_le _ (zero_le_one) _
section pos_part
lemma pos_part_to_simple_func (f : α →₁ₛ[μ] ℝ) :
to_simple_func (pos_part f) =ᵐ[μ] (to_simple_func f).pos_part :=
begin
have eq : ∀ a, (to_simple_func f).pos_part a = max ((to_simple_func f) a) 0 := λa, rfl,
have ae_eq : ∀ᵐ a ∂μ, to_simple_func (pos_part f) a = max ((to_simple_func f) a) 0,
{ filter_upwards [to_simple_func_eq_to_fun (pos_part f), Lp.coe_fn_pos_part (f : α →₁[μ] ℝ),
to_simple_func_eq_to_fun f],
assume a h₁ h₂ h₃,
rw [h₁, ← coe_coe, coe_pos_part, h₂, coe_coe, ← h₃] },
refine ae_eq.mono (assume a h, _),
rw [h, eq]
end
lemma neg_part_to_simple_func (f : α →₁ₛ[μ] ℝ) :
to_simple_func (neg_part f) =ᵐ[μ] (to_simple_func f).neg_part :=
begin
rw [simple_func.neg_part, measure_theory.simple_func.neg_part],
filter_upwards [pos_part_to_simple_func (-f), neg_to_simple_func f],
assume a h₁ h₂,
rw h₁,
show max _ _ = max _ _,
rw h₂,
refl
end
lemma integral_eq_norm_pos_part_sub (f : α →₁ₛ[μ] ℝ) :
integral f = ∥pos_part f∥ - ∥neg_part f∥ :=
begin
-- Convert things in `L¹` to their `simple_func` counterpart
have ae_eq₁ : (to_simple_func f).pos_part =ᵐ[μ] (to_simple_func (pos_part f)).map norm,
{ filter_upwards [pos_part_to_simple_func f],
assume a h,
rw [simple_func.map_apply, h],
conv_lhs { rw [← simple_func.pos_part_map_norm, simple_func.map_apply] } },
-- Convert things in `L¹` to their `simple_func` counterpart
have ae_eq₂ : (to_simple_func f).neg_part =ᵐ[μ] (to_simple_func (neg_part f)).map norm,
{ filter_upwards [neg_part_to_simple_func f],
assume a h,
rw [simple_func.map_apply, h],
conv_lhs { rw [← simple_func.neg_part_map_norm, simple_func.map_apply] } },
-- Convert things in `L¹` to their `simple_func` counterpart
have ae_eq : ∀ᵐ a ∂μ, (to_simple_func f).pos_part a - (to_simple_func f).neg_part a =
(to_simple_func (pos_part f)).map norm a - (to_simple_func (neg_part f)).map norm a,
{ filter_upwards [ae_eq₁, ae_eq₂],
assume a h₁ h₂,
rw [h₁, h₂] },
rw [integral, norm_eq_integral, norm_eq_integral, ← simple_func.integral_sub],
{ show (to_simple_func f).integral μ =
((to_simple_func (pos_part f)).map norm - (to_simple_func (neg_part f)).map norm).integral μ,
apply measure_theory.simple_func.integral_congr (simple_func.integrable f),
filter_upwards [ae_eq₁, ae_eq₂],
assume a h₁ h₂, show _ = _ - _,
rw [← h₁, ← h₂],
have := (to_simple_func f).pos_part_sub_neg_part,
conv_lhs {rw ← this},
refl },
{ exact (simple_func.integrable f).max_zero.congr ae_eq₁ },
{ exact (simple_func.integrable f).neg.max_zero.congr ae_eq₂ }
end
end pos_part
end simple_func_integral
end simple_func
open simple_func
local notation `Integral` := @integral_clm α E _ _ _ _ _ μ _
variables [normed_space ℝ E] [nondiscrete_normed_field 𝕜] [normed_space 𝕜 E]
[smul_comm_class ℝ 𝕜 E] [normed_space ℝ F] [complete_space E]
section integration_in_L1
local notation `to_L1` := coe_to_L1 α E ℝ
local attribute [instance] simple_func.normed_group simple_func.normed_space
open continuous_linear_map
variables (𝕜) [measurable_space 𝕜] [opens_measurable_space 𝕜]
/-- The Bochner integral in L1 space as a continuous linear map. -/
def integral_clm' : (α →₁[μ] E) →L[𝕜] E :=
(integral_clm' α E 𝕜 μ).extend
(coe_to_L1 α E 𝕜) simple_func.dense_range simple_func.uniform_inducing
variables {𝕜}
/-- The Bochner integral in L1 space as a continuous linear map over ℝ. -/
def integral_clm : (α →₁[μ] E) →L[ℝ] E := integral_clm' ℝ
/-- The Bochner integral in L1 space -/
def integral (f : α →₁[μ] E) : E := integral_clm f
lemma integral_eq (f : α →₁[μ] E) : integral f = integral_clm f := rfl
@[norm_cast] lemma simple_func.integral_L1_eq_integral (f : α →₁ₛ[μ] E) :
integral (f : α →₁[μ] E) = (simple_func.integral f) :=
uniformly_extend_of_ind simple_func.uniform_inducing simple_func.dense_range
(simple_func.integral_clm α E μ).uniform_continuous _
variables (α E)
@[simp] lemma integral_zero : integral (0 : α →₁[μ] E) = 0 :=
map_zero integral_clm
variables {α E}
lemma integral_add (f g : α →₁[μ] E) : integral (f + g) = integral f + integral g :=
map_add integral_clm f g
lemma integral_neg (f : α →₁[μ] E) : integral (-f) = - integral f :=
map_neg integral_clm f
lemma integral_sub (f g : α →₁[μ] E) : integral (f - g) = integral f - integral g :=
map_sub integral_clm f g
lemma integral_smul (c : 𝕜) (f : α →₁[μ] E) : integral (c • f) = c • integral f :=
map_smul (integral_clm' 𝕜) c f
local notation `Integral` := @integral_clm α E _ _ _ _ _ μ _ _
local notation `sIntegral` := @simple_func.integral_clm α E _ _ _ _ _ μ _
lemma norm_Integral_le_one : ∥Integral∥ ≤ 1 :=
calc ∥Integral∥ ≤ (1 : ℝ≥0) * ∥sIntegral∥ :
op_norm_extend_le _ _ _ $ λs, by {rw [nnreal.coe_one, one_mul], refl}
... = ∥sIntegral∥ : one_mul _
... ≤ 1 : norm_Integral_le_one
lemma norm_integral_le (f : α →₁[μ] E) : ∥integral f∥ ≤ ∥f∥ :=
calc ∥integral f∥ = ∥Integral f∥ : rfl
... ≤ ∥Integral∥ * ∥f∥ : le_op_norm _ _
... ≤ 1 * ∥f∥ : mul_le_mul_of_nonneg_right norm_Integral_le_one $ norm_nonneg _
... = ∥f∥ : one_mul _
@[continuity]
lemma continuous_integral : continuous (λ (f : α →₁[μ] E), integral f) :=
by simp [L1.integral, L1.integral_clm.continuous]
section pos_part
local attribute [instance] fact_one_le_one_ennreal
lemma integral_eq_norm_pos_part_sub (f : α →₁[μ] ℝ) :
integral f = ∥Lp.pos_part f∥ - ∥Lp.neg_part f∥ :=
begin
-- Use `is_closed_property` and `is_closed_eq`
refine @is_closed_property _ _ _ (coe : (α →₁ₛ[μ] ℝ) → (α →₁[μ] ℝ))
(λ f : α →₁[μ] ℝ, integral f = ∥Lp.pos_part f∥ - ∥Lp.neg_part f∥)
L1.simple_func.dense_range (is_closed_eq _ _) _ f,
{ exact cont _ },
{ refine continuous.sub (continuous_norm.comp Lp.continuous_pos_part)
(continuous_norm.comp Lp.continuous_neg_part) },
-- Show that the property holds for all simple functions in the `L¹` space.
{ assume s,
norm_cast,
rw [← simple_func.norm_eq, ← simple_func.norm_eq],
exact simple_func.integral_eq_norm_pos_part_sub _}
end
end pos_part
end integration_in_L1
end L1
variables [normed_group E] [second_countable_topology E] [normed_space ℝ E] [complete_space E]
[measurable_space E] [borel_space E]
[nondiscrete_normed_field 𝕜] [normed_space 𝕜 E] [smul_comm_class ℝ 𝕜 E]
[normed_group F] [second_countable_topology F] [normed_space ℝ F] [complete_space F]
[measurable_space F] [borel_space F]
/-- The Bochner integral -/
def integral (μ : measure α) (f : α → E) : E :=
if hf : integrable f μ then L1.integral (hf.to_L1 f) else 0
/-! In the notation for integrals, an expression like `∫ x, g ∥x∥ ∂μ` will not be parsed correctly,
and needs parentheses. We do not set the binding power of `r` to `0`, because then
`∫ x, f x = 0` will be parsed incorrectly. -/
notation `∫` binders `, ` r:(scoped:60 f, f) ` ∂` μ:70 := integral μ r
notation `∫` binders `, ` r:(scoped:60 f, integral volume f) := r
notation `∫` binders ` in ` s `, ` r:(scoped:60 f, f) ` ∂` μ:70 := integral (measure.restrict μ s) r
notation `∫` binders ` in ` s `, ` r:(scoped:60 f, integral (measure.restrict volume s) f) := r
section properties
open continuous_linear_map measure_theory.simple_func
variables {f g : α → E} {μ : measure α}
lemma integral_eq (f : α → E) (hf : integrable f μ) :
∫ a, f a ∂μ = L1.integral (hf.to_L1 f) :=
dif_pos hf
lemma L1.integral_eq_integral (f : α →₁[μ] E) : L1.integral f = ∫ a, f a ∂μ :=
by rw [integral_eq _ (L1.integrable_coe_fn f), integrable.to_L1_coe_fn]
lemma integral_undef (h : ¬ integrable f μ) : ∫ a, f a ∂μ = 0 :=
dif_neg h
lemma integral_non_ae_measurable (h : ¬ ae_measurable f μ) : ∫ a, f a ∂μ = 0 :=
integral_undef $ not_and_of_not_left _ h
variables (α E)
lemma integral_zero : ∫ a : α, (0:E) ∂μ = 0 :=
by { rw [integral_eq _ (integrable_zero α E μ)], exact L1.integral_zero _ _ }
@[simp] lemma integral_zero' : integral μ (0 : α → E) = 0 :=
integral_zero α E
variables {α E}
lemma integral_add (hf : integrable f μ) (hg : integrable g μ) :
∫ a, f a + g a ∂μ = ∫ a, f a ∂μ + ∫ a, g a ∂μ :=
begin
rw [integral_eq, integral_eq f hf, integral_eq g hg, ← L1.integral_add],
{ refl },
{ exact hf.add hg }
end
lemma integral_add' (hf : integrable f μ) (hg : integrable g μ) :
∫ a, (f + g) a ∂μ = ∫ a, f a ∂μ + ∫ a, g a ∂μ :=
integral_add hf hg
lemma integral_neg (f : α → E) : ∫ a, -f a ∂μ = - ∫ a, f a ∂μ :=
begin
by_cases hf : integrable f μ,
{ rw [integral_eq f hf, integral_eq (λa, - f a) hf.neg, ← L1.integral_neg],
refl },
{ rw [integral_undef hf, integral_undef, neg_zero], rwa [← integrable_neg_iff] at hf }
end
lemma integral_neg' (f : α → E) : ∫ a, (-f) a ∂μ = - ∫ a, f a ∂μ :=
integral_neg f
lemma integral_sub (hf : integrable f μ) (hg : integrable g μ) :
∫ a, f a - g a ∂μ = ∫ a, f a ∂μ - ∫ a, g a ∂μ :=
by { simp only [sub_eq_add_neg, ← integral_neg], exact integral_add hf hg.neg }
lemma integral_sub' (hf : integrable f μ) (hg : integrable g μ) :
∫ a, (f - g) a ∂μ = ∫ a, f a ∂μ - ∫ a, g a ∂μ :=
integral_sub hf hg
lemma integral_smul [measurable_space 𝕜] [opens_measurable_space 𝕜] (c : 𝕜) (f : α → E) :
∫ a, c • (f a) ∂μ = c • ∫ a, f a ∂μ :=
begin
by_cases hf : integrable f μ,
{ rw [integral_eq f hf, integral_eq (λa, c • (f a)), integrable.to_L1_smul, L1.integral_smul], },
{ by_cases hr : c = 0,
{ simp only [hr, measure_theory.integral_zero, zero_smul] },
have hf' : ¬ integrable (λ x, c • f x) μ,
{ change ¬ integrable (c • f) μ, rwa [integrable_smul_iff hr f] },
rw [integral_undef hf, integral_undef hf', smul_zero] }
end
lemma integral_mul_left (r : ℝ) (f : α → ℝ) : ∫ a, r * (f a) ∂μ = r * ∫ a, f a ∂μ :=
integral_smul r f
lemma integral_mul_right (r : ℝ) (f : α → ℝ) : ∫ a, (f a) * r ∂μ = ∫ a, f a ∂μ * r :=
by { simp only [mul_comm], exact integral_mul_left r f }
lemma integral_div (r : ℝ) (f : α → ℝ) : ∫ a, (f a) / r ∂μ = ∫ a, f a ∂μ / r :=
integral_mul_right r⁻¹ f
lemma integral_congr_ae (h : f =ᵐ[μ] g) : ∫ a, f a ∂μ = ∫ a, g a ∂μ :=
begin
by_cases hfi : integrable f μ,
{ have hgi : integrable g μ := hfi.congr h,
rw [integral_eq f hfi, integral_eq g hgi, (integrable.to_L1_eq_to_L1_iff f g hfi hgi).2 h] },
{ have hgi : ¬ integrable g μ, { rw integrable_congr h at hfi, exact hfi },
rw [integral_undef hfi, integral_undef hgi] },
end
@[simp] lemma L1.integral_of_fun_eq_integral {f : α → E} (hf : integrable f μ) :
∫ a, (hf.to_L1 f) a ∂μ = ∫ a, f a ∂μ :=
integral_congr_ae $ by simp [integrable.coe_fn_to_L1]
@[continuity]
lemma continuous_integral : continuous (λ (f : α →₁[μ] E), ∫ a, f a ∂μ) :=
by { simp only [← L1.integral_eq_integral], exact L1.continuous_integral }
lemma norm_integral_le_lintegral_norm (f : α → E) :
∥∫ a, f a ∂μ∥ ≤ ennreal.to_real (∫⁻ a, (ennreal.of_real ∥f a∥) ∂μ) :=
begin
by_cases hf : integrable f μ,
{ rw [integral_eq f hf, ← integrable.norm_to_L1_eq_lintegral_norm f hf],
exact L1.norm_integral_le _ },
{ rw [integral_undef hf, norm_zero], exact to_real_nonneg }
end
lemma ennnorm_integral_le_lintegral_ennnorm (f : α → E) :
(nnnorm (∫ a, f a ∂μ) : ℝ≥0∞) ≤ ∫⁻ a, (nnnorm (f a)) ∂μ :=
by { simp_rw [← of_real_norm_eq_coe_nnnorm], apply ennreal.of_real_le_of_le_to_real,
exact norm_integral_le_lintegral_norm f }
lemma integral_eq_zero_of_ae {f : α → E} (hf : f =ᵐ[μ] 0) : ∫ a, f a ∂μ = 0 :=
by simp [integral_congr_ae hf, integral_zero]
/-- If `f` has finite integral, then `∫ x in s, f x ∂μ` is absolutely continuous in `s`: it tends
to zero as `μ s` tends to zero. -/
lemma has_finite_integral.tendsto_set_integral_nhds_zero {ι} {f : α → E}
(hf : has_finite_integral f μ) {l : filter ι} {s : ι → set α}
(hs : tendsto (μ ∘ s) l (𝓝 0)) :
tendsto (λ i, ∫ x in s i, f x ∂μ) l (𝓝 0) :=
begin
rw [tendsto_zero_iff_norm_tendsto_zero],
simp_rw [← coe_nnnorm, ← nnreal.coe_zero, nnreal.tendsto_coe, ← ennreal.tendsto_coe,
ennreal.coe_zero],
exact tendsto_of_tendsto_of_tendsto_of_le_of_le tendsto_const_nhds
(tendsto_set_lintegral_zero hf hs) (λ i, zero_le _)
(λ i, ennnorm_integral_le_lintegral_ennnorm _)
end
/-- If `f` is integrable, then `∫ x in s, f x ∂μ` is absolutely continuous in `s`: it tends
to zero as `μ s` tends to zero. -/
lemma integrable.tendsto_set_integral_nhds_zero {ι} {f : α → E}
(hf : integrable f μ) {l : filter ι} {s : ι → set α} (hs : tendsto (μ ∘ s) l (𝓝 0)) :
tendsto (λ i, ∫ x in s i, f x ∂μ) l (𝓝 0) :=
hf.2.tendsto_set_integral_nhds_zero hs
/-- If `F i → f` in `L1`, then `∫ x, F i x ∂μ → ∫ x, f x∂μ`. -/
lemma tendsto_integral_of_L1 {ι} (f : α → E) (hfi : integrable f μ)
{F : ι → α → E} {l : filter ι} (hFi : ∀ᶠ i in l, integrable (F i) μ)
(hF : tendsto (λ i, ∫⁻ x, edist (F i x) (f x) ∂μ) l (𝓝 0)) :
tendsto (λ i, ∫ x, F i x ∂μ) l (𝓝 $ ∫ x, f x ∂μ) :=
begin
rw [tendsto_iff_norm_tendsto_zero],
replace hF : tendsto (λ i, ennreal.to_real $ ∫⁻ x, edist (F i x) (f x) ∂μ) l (𝓝 0) :=
(ennreal.tendsto_to_real zero_ne_top).comp hF,
refine squeeze_zero_norm' (hFi.mp $ hFi.mono $ λ i hFi hFm, _) hF,
simp only [norm_norm, ← integral_sub hFi hfi, edist_dist, dist_eq_norm],
apply norm_integral_le_lintegral_norm
end
/-- Lebesgue dominated convergence theorem provides sufficient conditions under which almost
everywhere convergence of a sequence of functions implies the convergence of their integrals. -/
theorem tendsto_integral_of_dominated_convergence {F : ℕ → α → E} {f : α → E} (bound : α → ℝ)
(F_measurable : ∀ n, ae_measurable (F n) μ)
(f_measurable : ae_measurable f μ)
(bound_integrable : integrable bound μ)
(h_bound : ∀ n, ∀ᵐ a ∂μ, ∥F n a∥ ≤ bound a)
(h_lim : ∀ᵐ a ∂μ, tendsto (λ n, F n a) at_top (𝓝 (f a))) :
tendsto (λn, ∫ a, F n a ∂μ) at_top (𝓝 $ ∫ a, f a ∂μ) :=
begin
/- To show `(∫ a, F n a) --> (∫ f)`, suffices to show `∥∫ a, F n a - ∫ f∥ --> 0` -/
rw tendsto_iff_norm_tendsto_zero,
/- But `0 ≤ ∥∫ a, F n a - ∫ f∥ = ∥∫ a, (F n a - f a) ∥ ≤ ∫ a, ∥F n a - f a∥, and thus we apply the
sandwich theorem and prove that `∫ a, ∥F n a - f a∥ --> 0` -/
have lintegral_norm_tendsto_zero :
tendsto (λn, ennreal.to_real $ ∫⁻ a, (ennreal.of_real ∥F n a - f a∥) ∂μ) at_top (𝓝 0) :=
(tendsto_to_real zero_ne_top).comp
(tendsto_lintegral_norm_of_dominated_convergence
F_measurable f_measurable bound_integrable.has_finite_integral h_bound h_lim),
-- Use the sandwich theorem
refine squeeze_zero (λ n, norm_nonneg _) _ lintegral_norm_tendsto_zero,
-- Show `∥∫ a, F n a - ∫ f∥ ≤ ∫ a, ∥F n a - f a∥` for all `n`
{ assume n,
have h₁ : integrable (F n) μ := bound_integrable.mono' (F_measurable n) (h_bound _),
have h₂ : integrable f μ :=
⟨f_measurable, has_finite_integral_of_dominated_convergence
bound_integrable.has_finite_integral h_bound h_lim⟩,
rw ← integral_sub h₁ h₂,
exact norm_integral_le_lintegral_norm _ }
end
/-- Lebesgue dominated convergence theorem for filters with a countable basis -/
lemma tendsto_integral_filter_of_dominated_convergence {ι} {l : filter ι}
{F : ι → α → E} {f : α → E} (bound : α → ℝ)
(hl_cb : l.is_countably_generated)
(hF_meas : ∀ᶠ n in l, ae_measurable (F n) μ)
(f_measurable : ae_measurable f μ)
(h_bound : ∀ᶠ n in l, ∀ᵐ a ∂μ, ∥F n a∥ ≤ bound a)
(bound_integrable : integrable bound μ)
(h_lim : ∀ᵐ a ∂μ, tendsto (λ n, F n a) l (𝓝 (f a))) :
tendsto (λn, ∫ a, F n a ∂μ) l (𝓝 $ ∫ a, f a ∂μ) :=
begin
rw hl_cb.tendsto_iff_seq_tendsto,
{ intros x xl,
have hxl, { rw tendsto_at_top' at xl, exact xl },
have h := inter_mem_sets hF_meas h_bound,
replace h := hxl _ h,
rcases h with ⟨k, h⟩,
rw ← tendsto_add_at_top_iff_nat k,
refine tendsto_integral_of_dominated_convergence _ _ _ _ _ _,
{ exact bound },
{ intro, refine (h _ _).1, exact nat.le_add_left _ _ },
{ assumption },
{ assumption },
{ intro, refine (h _ _).2, exact nat.le_add_left _ _ },
{ filter_upwards [h_lim],
assume a h_lim,
apply @tendsto.comp _ _ _ (λn, x (n + k)) (λn, F n a),
{ assumption },
rw tendsto_add_at_top_iff_nat,
assumption } },
end
variables {X : Type*} [topological_space X] [first_countable_topology X]
lemma continuous_at_of_dominated {F : X → α → E} {x₀ : X} {bound : α → ℝ}
(hF_meas : ∀ᶠ x in 𝓝 x₀, ae_measurable (F x) μ)
(h_bound : ∀ᶠ x in 𝓝 x₀, ∀ᵐ a ∂μ, ∥F x a∥ ≤ bound a)
(bound_integrable : integrable bound μ) (h_cont : ∀ᵐ a ∂μ, continuous_at (λ x, F x a) x₀) :
continuous_at (λ x, ∫ a, F x a ∂μ) x₀ :=
tendsto_integral_filter_of_dominated_convergence bound
(first_countable_topology.nhds_generated_countable x₀) ‹_›
(mem_of_mem_nhds hF_meas : _) ‹_› ‹_› ‹_›
lemma continuous_of_dominated {F : X → α → E} {bound : α → ℝ}
(hF_meas : ∀ x, ae_measurable (F x) μ) (h_bound : ∀ x, ∀ᵐ a ∂μ, ∥F x a∥ ≤ bound a)
(bound_integrable : integrable bound μ) (h_cont : ∀ᵐ a ∂μ, continuous (λ x, F x a)) :
continuous (λ x, ∫ a, F x a ∂μ) :=
continuous_iff_continuous_at.mpr (λ x₀, continuous_at_of_dominated (eventually_of_forall hF_meas)
(eventually_of_forall h_bound) ‹_› $ h_cont.mono $ λ _, continuous.continuous_at)
/-- The Bochner integral of a real-valued function `f : α → ℝ` is the difference between the
integral of the positive part of `f` and the integral of the negative part of `f`. -/
lemma integral_eq_lintegral_pos_part_sub_lintegral_neg_part {f : α → ℝ} (hf : integrable f μ) :
∫ a, f a ∂μ =
ennreal.to_real (∫⁻ a, (ennreal.of_real $ f a) ∂μ) -
ennreal.to_real (∫⁻ a, (ennreal.of_real $ - f a) ∂μ) :=
let f₁ := hf.to_L1 f in
-- Go to the `L¹` space
have eq₁ : ennreal.to_real (∫⁻ a, (ennreal.of_real $ f a) ∂μ) = ∥Lp.pos_part f₁∥ :=
begin
rw L1.norm_def,
congr' 1,
apply lintegral_congr_ae,
filter_upwards [Lp.coe_fn_pos_part f₁, hf.coe_fn_to_L1],
assume a h₁ h₂,
rw [h₁, h₂, ennreal.of_real],
congr' 1,
apply nnreal.eq,
simp [real.norm_of_nonneg, le_max_right, real.coe_to_nnreal]
end,
-- Go to the `L¹` space
have eq₂ : ennreal.to_real (∫⁻ a, (ennreal.of_real $ - f a) ∂μ) = ∥Lp.neg_part f₁∥ :=
begin
rw L1.norm_def,
congr' 1,
apply lintegral_congr_ae,
filter_upwards [Lp.coe_fn_neg_part f₁, hf.coe_fn_to_L1],
assume a h₁ h₂,
rw [h₁, h₂, ennreal.of_real],
congr' 1,
apply nnreal.eq,
simp only [real.norm_of_nonneg, min_le_right, neg_nonneg, real.coe_to_nnreal', subtype.coe_mk],
rw [← max_neg_neg, coe_nnnorm, neg_zero, real.norm_of_nonneg (le_max_right (-f a) 0)]
end,
begin
rw [eq₁, eq₂, integral, dif_pos],
exact L1.integral_eq_norm_pos_part_sub _
end
lemma integral_eq_lintegral_of_nonneg_ae {f : α → ℝ} (hf : 0 ≤ᵐ[μ] f) (hfm : ae_measurable f μ) :
∫ a, f a ∂μ = ennreal.to_real (∫⁻ a, (ennreal.of_real $ f a) ∂μ) :=
begin
by_cases hfi : integrable f μ,
{ rw integral_eq_lintegral_pos_part_sub_lintegral_neg_part hfi,
have h_min : ∫⁻ a, ennreal.of_real (-f a) ∂μ = 0,
{ rw lintegral_eq_zero_iff',
{ refine hf.mono _,
simp only [pi.zero_apply],
assume a h,
simp only [h, neg_nonpos, of_real_eq_zero], },
{ exact measurable_of_real.comp_ae_measurable hfm.neg } },
rw [h_min, zero_to_real, _root_.sub_zero] },
{ rw integral_undef hfi,
simp_rw [integrable, hfm, has_finite_integral_iff_norm, lt_top_iff_ne_top, ne.def, true_and,
not_not] at hfi,
have : ∫⁻ (a : α), ennreal.of_real (f a) ∂μ = ∫⁻ a, (ennreal.of_real ∥f a∥) ∂μ,
{ refine lintegral_congr_ae (hf.mono $ assume a h, _),
rw [real.norm_eq_abs, abs_of_nonneg h] },
rw [this, hfi], refl }
end
lemma integral_eq_integral_pos_part_sub_integral_neg_part {f : α → ℝ} (hf : integrable f μ) :
∫ a, f a ∂μ = (∫ a, real.to_nnreal (f a) ∂μ) - (∫ a, real.to_nnreal (-f a) ∂μ) :=
begin
rw [← integral_sub hf.real_to_nnreal],
{ simp },
{ exact hf.neg.real_to_nnreal }
end
lemma integral_nonneg_of_ae {f : α → ℝ} (hf : 0 ≤ᵐ[μ] f) : 0 ≤ ∫ a, f a ∂μ :=
begin
by_cases hfm : ae_measurable f μ,
{ rw integral_eq_lintegral_of_nonneg_ae hf hfm, exact to_real_nonneg },
{ rw integral_non_ae_measurable hfm }
end
lemma lintegral_coe_eq_integral (f : α → ℝ≥0) (hfi : integrable (λ x, (f x : ℝ)) μ) :
∫⁻ a, f a ∂μ = ennreal.of_real ∫ a, f a ∂μ :=
begin
simp_rw [integral_eq_lintegral_of_nonneg_ae (eventually_of_forall (λ x, (f x).coe_nonneg))
hfi.ae_measurable, ← ennreal.coe_nnreal_eq], rw [ennreal.of_real_to_real],
rw [← lt_top_iff_ne_top], convert hfi.has_finite_integral, ext1 x, rw [nnreal.nnnorm_eq]
end
lemma integral_to_real {f : α → ℝ≥0∞} (hfm : ae_measurable f μ) (hf : ∀ᵐ x ∂μ, f x < ∞) :
∫ a, (f a).to_real ∂μ = (∫⁻ a, f a ∂μ).to_real :=
begin
rw [integral_eq_lintegral_of_nonneg_ae _ hfm.ennreal_to_real],
{ rw lintegral_congr_ae, refine hf.mp (eventually_of_forall _),
intros x hx, rw [lt_top_iff_ne_top] at hx, simp [hx] },
{ exact (eventually_of_forall $ λ x, ennreal.to_real_nonneg) }
end
lemma integral_nonneg {f : α → ℝ} (hf : 0 ≤ f) : 0 ≤ ∫ a, f a ∂μ :=
integral_nonneg_of_ae $ eventually_of_forall hf
lemma integral_nonpos_of_ae {f : α → ℝ} (hf : f ≤ᵐ[μ] 0) : ∫ a, f a ∂μ ≤ 0 :=
begin
have hf : 0 ≤ᵐ[μ] (-f) := hf.mono (assume a h, by rwa [pi.neg_apply, pi.zero_apply, neg_nonneg]),
have : 0 ≤ ∫ a, -f a ∂μ := integral_nonneg_of_ae hf,
rwa [integral_neg, neg_nonneg] at this,
end
lemma integral_nonpos {f : α → ℝ} (hf : f ≤ 0) : ∫ a, f a ∂μ ≤ 0 :=
integral_nonpos_of_ae $ eventually_of_forall hf
lemma integral_eq_zero_iff_of_nonneg_ae {f : α → ℝ} (hf : 0 ≤ᵐ[μ] f) (hfi : integrable f μ) :
∫ x, f x ∂μ = 0 ↔ f =ᵐ[μ] 0 :=
by simp_rw [integral_eq_lintegral_of_nonneg_ae hf hfi.1, ennreal.to_real_eq_zero_iff,
lintegral_eq_zero_iff' (ennreal.measurable_of_real.comp_ae_measurable hfi.1),
← ennreal.not_lt_top, ← has_finite_integral_iff_of_real hf, hfi.2, not_true, or_false,
← hf.le_iff_eq, filter.eventually_eq, filter.eventually_le, (∘), pi.zero_apply,
ennreal.of_real_eq_zero]
lemma integral_eq_zero_iff_of_nonneg {f : α → ℝ} (hf : 0 ≤ f) (hfi : integrable f μ) :
∫ x, f x ∂μ = 0 ↔ f =ᵐ[μ] 0 :=
integral_eq_zero_iff_of_nonneg_ae (eventually_of_forall hf) hfi
lemma integral_pos_iff_support_of_nonneg_ae {f : α → ℝ} (hf : 0 ≤ᵐ[μ] f) (hfi : integrable f μ) :
(0 < ∫ x, f x ∂μ) ↔ 0 < μ (function.support f) :=
by simp_rw [(integral_nonneg_of_ae hf).lt_iff_ne, pos_iff_ne_zero, ne.def, @eq_comm ℝ 0,
integral_eq_zero_iff_of_nonneg_ae hf hfi, filter.eventually_eq, ae_iff, pi.zero_apply,
function.support]
lemma integral_pos_iff_support_of_nonneg {f : α → ℝ} (hf : 0 ≤ f) (hfi : integrable f μ) :
(0 < ∫ x, f x ∂μ) ↔ 0 < μ (function.support f) :=
integral_pos_iff_support_of_nonneg_ae (eventually_of_forall hf) hfi
section normed_group
variables {H : Type*} [normed_group H] [second_countable_topology H] [measurable_space H]
[borel_space H]
lemma L1.norm_eq_integral_norm (f : α →₁[μ] H) : ∥f∥ = ∫ a, ∥f a∥ ∂μ :=
begin
simp only [snorm, snorm', ennreal.one_to_real, ennreal.rpow_one, Lp.norm_def,
if_false, ennreal.one_ne_top, one_ne_zero, _root_.div_one],
rw integral_eq_lintegral_of_nonneg_ae (eventually_of_forall (by simp [norm_nonneg]))
(continuous_norm.measurable.comp_ae_measurable (Lp.ae_measurable f)),
simp [of_real_norm_eq_coe_nnnorm]
end
lemma L1.norm_of_fun_eq_integral_norm {f : α → H} (hf : integrable f μ) :
∥hf.to_L1 f∥ = ∫ a, ∥f a∥ ∂μ :=
begin
rw L1.norm_eq_integral_norm,
refine integral_congr_ae _,
apply hf.coe_fn_to_L1.mono,
intros a ha,
simp [ha]
end
end normed_group
lemma integral_mono_ae {f g : α → ℝ} (hf : integrable f μ) (hg : integrable g μ) (h : f ≤ᵐ[μ] g) :
∫ a, f a ∂μ ≤ ∫ a, g a ∂μ :=
le_of_sub_nonneg $ integral_sub hg hf ▸ integral_nonneg_of_ae $ h.mono (λ a, sub_nonneg_of_le)
@[mono] lemma integral_mono {f g : α → ℝ} (hf : integrable f μ) (hg : integrable g μ) (h : f ≤ g) :
∫ a, f a ∂μ ≤ ∫ a, g a ∂μ :=
integral_mono_ae hf hg $ eventually_of_forall h
lemma integral_mono_of_nonneg {f g : α → ℝ} (hf : 0 ≤ᵐ[μ] f) (hgi : integrable g μ)
(h : f ≤ᵐ[μ] g) : ∫ a, f a ∂μ ≤ ∫ a, g a ∂μ :=
begin
by_cases hfm : ae_measurable f μ,
{ refine integral_mono_ae ⟨hfm, _⟩ hgi h,
refine (hgi.has_finite_integral.mono $ h.mp $ hf.mono $ λ x hf hfg, _),
simpa [real.norm_eq_abs, abs_of_nonneg hf, abs_of_nonneg (le_trans hf hfg)] },
{ rw [integral_non_ae_measurable hfm],
exact integral_nonneg_of_ae (hf.trans h) }
end
lemma norm_integral_le_integral_norm (f : α → E) : ∥(∫ a, f a ∂μ)∥ ≤ ∫ a, ∥f a∥ ∂μ :=
have le_ae : ∀ᵐ a ∂μ, 0 ≤ ∥f a∥ := eventually_of_forall (λa, norm_nonneg _),
classical.by_cases
( λh : ae_measurable f μ,
calc ∥∫ a, f a ∂μ∥ ≤ ennreal.to_real (∫⁻ a, (ennreal.of_real ∥f a∥) ∂μ) :
norm_integral_le_lintegral_norm _
... = ∫ a, ∥f a∥ ∂μ : (integral_eq_lintegral_of_nonneg_ae le_ae $ ae_measurable.norm h).symm )
( λh : ¬ae_measurable f μ,
begin
rw [integral_non_ae_measurable h, norm_zero],
exact integral_nonneg_of_ae le_ae
end )
lemma norm_integral_le_of_norm_le {f : α → E} {g : α → ℝ} (hg : integrable g μ)
(h : ∀ᵐ x ∂μ, ∥f x∥ ≤ g x) : ∥∫ x, f x ∂μ∥ ≤ ∫ x, g x ∂μ :=
calc ∥∫ x, f x ∂μ∥ ≤ ∫ x, ∥f x∥ ∂μ : norm_integral_le_integral_norm f
... ≤ ∫ x, g x ∂μ :
integral_mono_of_nonneg (eventually_of_forall $ λ x, norm_nonneg _) hg h
lemma integral_finset_sum {ι} (s : finset ι) {f : ι → α → E} (hf : ∀ i, integrable (f i) μ) :
∫ a, ∑ i in s, f i a ∂μ = ∑ i in s, ∫ a, f i a ∂μ :=
begin
refine finset.induction_on s _ _,
{ simp only [integral_zero, finset.sum_empty] },
{ assume i s his ih,
simp only [his, finset.sum_insert, not_false_iff],
rw [integral_add (hf _) (integrable_finset_sum s hf), ih] }
end
lemma simple_func.integral_eq_integral (f : α →ₛ E) (hfi : integrable f μ) :
f.integral μ = ∫ x, f x ∂μ :=
begin
rw [integral_eq f hfi, ← L1.simple_func.to_L1_eq_to_L1,
L1.simple_func.integral_L1_eq_integral, L1.simple_func.integral_eq_integral],
exact simple_func.integral_congr hfi (L1.simple_func.to_simple_func_to_L1 _ _).symm
end
lemma simple_func.integral_eq_sum (f : α →ₛ E) (hfi : integrable f μ) :
∫ x, f x ∂μ = ∑ x in f.range, (ennreal.to_real (μ (f ⁻¹' {x}))) • x :=
by rw [← f.integral_eq_integral hfi, simple_func.integral]
@[simp] lemma integral_const (c : E) : ∫ x : α, c ∂μ = (μ univ).to_real • c :=
begin
by_cases hμ : μ univ < ∞,
{ haveI : finite_measure μ := ⟨hμ⟩,
calc ∫ x : α, c ∂μ = (simple_func.const α c).integral μ :
((simple_func.const α c).integral_eq_integral (integrable_const _)).symm
... = _ : _,
rw [simple_func.integral],
by_cases ha : nonempty α,
{ resetI, simp [preimage_const_of_mem] },
{ simp [μ.eq_zero_of_not_nonempty ha] } },
{ by_cases hc : c = 0,
{ simp [hc, integral_zero] },
{ have : ¬integrable (λ x : α, c) μ,
{ simp only [integrable_const_iff, not_or_distrib],
exact ⟨hc, hμ⟩ },
simp only [not_lt, top_le_iff] at hμ,
simp [integral_undef, *] } }
end
lemma norm_integral_le_of_norm_le_const [finite_measure μ] {f : α → E} {C : ℝ}
(h : ∀ᵐ x ∂μ, ∥f x∥ ≤ C) :
∥∫ x, f x ∂μ∥ ≤ C * (μ univ).to_real :=
calc ∥∫ x, f x ∂μ∥ ≤ ∫ x, C ∂μ : norm_integral_le_of_norm_le (integrable_const C) h
... = C * (μ univ).to_real : by rw [integral_const, smul_eq_mul, mul_comm]
lemma tendsto_integral_approx_on_univ_of_measurable
{f : α → E} (fmeas : measurable f) (hf : integrable f μ) :
tendsto (λ n, (simple_func.approx_on f fmeas univ 0 trivial n).integral μ) at_top
(𝓝 $ ∫ x, f x ∂μ) :=
begin
have : tendsto (λ n, ∫ x, simple_func.approx_on f fmeas univ 0 trivial n x ∂μ)
at_top (𝓝 $ ∫ x, f x ∂μ) :=
tendsto_integral_of_L1 _ hf
(eventually_of_forall $ simple_func.integrable_approx_on_univ fmeas hf)
(simple_func.tendsto_approx_on_univ_L1_edist fmeas hf),
simpa only [simple_func.integral_eq_integral, simple_func.integrable_approx_on_univ fmeas hf]
end
variable {ν : measure α}
private lemma integral_add_measure_of_measurable
{f : α → E} (fmeas : measurable f) (hμ : integrable f μ) (hν : integrable f ν) :
∫ x, f x ∂(μ + ν) = ∫ x, f x ∂μ + ∫ x, f x ∂ν :=
begin
have hfi := hμ.add_measure hν,
refine tendsto_nhds_unique (tendsto_integral_approx_on_univ_of_measurable fmeas hfi) _,
simpa only [simple_func.integral_add_measure _
(simple_func.integrable_approx_on_univ fmeas hfi _)]
using (tendsto_integral_approx_on_univ_of_measurable fmeas hμ).add
(tendsto_integral_approx_on_univ_of_measurable fmeas hν)
end
lemma integral_add_measure {f : α → E} (hμ : integrable f μ) (hν : integrable f ν) :
∫ x, f x ∂(μ + ν) = ∫ x, f x ∂μ + ∫ x, f x ∂ν :=
begin
have h : ae_measurable f (μ + ν) := hμ.ae_measurable.add_measure hν.ae_measurable,
let g := h.mk f,
have A : f =ᵐ[μ + ν] g := h.ae_eq_mk,
have B : f =ᵐ[μ] g := A.filter_mono (ae_mono (measure.le_add_right (le_refl μ))),
have C : f =ᵐ[ν] g := A.filter_mono (ae_mono (measure.le_add_left (le_refl ν))),
calc ∫ x, f x ∂(μ + ν) = ∫ x, g x ∂(μ + ν) : integral_congr_ae A
... = ∫ x, g x ∂μ + ∫ x, g x ∂ν :
integral_add_measure_of_measurable h.measurable_mk ((integrable_congr B).1 hμ)
((integrable_congr C).1 hν)
... = ∫ x, f x ∂μ + ∫ x, f x ∂ν :
by { congr' 1, { exact integral_congr_ae B.symm }, { exact integral_congr_ae C.symm } }
end
@[simp] lemma integral_zero_measure (f : α → E) : ∫ x, f x ∂0 = 0 :=
norm_le_zero_iff.1 $ le_trans (norm_integral_le_lintegral_norm f) $ by simp
private lemma integral_smul_measure_aux {f : α → E} {c : ℝ≥0∞}
(h0 : 0 < c) (hc : c < ∞) (fmeas : measurable f) (hfi : integrable f μ) :
∫ x, f x ∂(c • μ) = c.to_real • ∫ x, f x ∂μ :=
begin
refine tendsto_nhds_unique _
(tendsto_const_nhds.smul (tendsto_integral_approx_on_univ_of_measurable fmeas hfi)),
convert tendsto_integral_approx_on_univ_of_measurable fmeas (hfi.smul_measure hc),
simp only [simple_func.integral, measure.smul_apply, finset.smul_sum, smul_smul,
ennreal.to_real_mul]
end
@[simp] lemma integral_smul_measure (f : α → E) (c : ℝ≥0∞) :
∫ x, f x ∂(c • μ) = c.to_real • ∫ x, f x ∂μ :=
begin
-- First we consider “degenerate” cases:
-- `c = 0`
rcases (zero_le c).eq_or_lt with rfl|h0, { simp },
-- `f` is not almost everywhere measurable
by_cases hfm : ae_measurable f μ, swap,
{ have : ¬ (ae_measurable f (c • μ)), by simpa [ne_of_gt h0] using hfm,
simp [integral_non_ae_measurable, hfm, this] },
-- `c = ∞`
rcases (le_top : c ≤ ∞).eq_or_lt with rfl|hc,
{ rw [ennreal.top_to_real, zero_smul],
by_cases hf : f =ᵐ[μ] 0,
{ have : f =ᵐ[∞ • μ] 0 := ae_smul_measure hf ∞,
exact integral_eq_zero_of_ae this },
{ apply integral_undef,
rw [integrable, has_finite_integral, iff_true_intro (hfm.smul_measure ∞), true_and,
lintegral_smul_measure, top_mul, if_neg],
{ apply lt_irrefl },
{ rw [lintegral_eq_zero_iff' hfm.ennnorm],
refine λ h, hf (h.mono $ λ x, _),
simp } } },
-- `f` is not integrable and `0 < c < ∞`
by_cases hfi : integrable f μ, swap,
{ rw [integral_undef hfi, smul_zero],
refine integral_undef (mt (λ h, _) hfi),
convert h.smul_measure (ennreal.inv_lt_top.2 h0),
rw [smul_smul, ennreal.inv_mul_cancel (ne_of_gt h0) (ne_of_lt hc), one_smul] },
-- Main case: `0 < c < ∞`, `f` is almost everywhere measurable and integrable
let g := hfm.mk f,
calc ∫ x, f x ∂(c • μ) = ∫ x, g x ∂(c • μ) : integral_congr_ae $ ae_smul_measure hfm.ae_eq_mk c
... = c.to_real • ∫ x, g x ∂μ :
integral_smul_measure_aux h0 hc hfm.measurable_mk $ hfi.congr hfm.ae_eq_mk
... = c.to_real • ∫ x, f x ∂μ :
by { congr' 1, exact integral_congr_ae (hfm.ae_eq_mk.symm) }
end
lemma integral_map_of_measurable {β} [measurable_space β] {φ : α → β} (hφ : measurable φ)
{f : β → E} (hfm : measurable f) :
∫ y, f y ∂(measure.map φ μ) = ∫ x, f (φ x) ∂μ :=
begin
by_cases hfi : integrable f (measure.map φ μ), swap,
{ rw [integral_undef hfi, integral_undef],
rwa [← integrable_map_measure hfm.ae_measurable hφ] },
refine tendsto_nhds_unique (tendsto_integral_approx_on_univ_of_measurable hfm hfi) _,
convert tendsto_integral_approx_on_univ_of_measurable (hfm.comp hφ)
((integrable_map_measure hfm.ae_measurable hφ).1 hfi),
ext1 i,
simp only [simple_func.approx_on_comp, simple_func.integral, measure.map_apply, hφ,
simple_func.measurable_set_preimage, ← preimage_comp, simple_func.coe_comp],
refine (finset.sum_subset (simple_func.range_comp_subset_range _ hφ) (λ y _ hy, _)).symm,
rw [simple_func.mem_range, ← set.preimage_singleton_eq_empty, simple_func.coe_comp] at hy,
simp [hy]
end
lemma integral_map {β} [measurable_space β] {φ : α → β} (hφ : measurable φ)
{f : β → E} (hfm : ae_measurable f (measure.map φ μ)) :
∫ y, f y ∂(measure.map φ μ) = ∫ x, f (φ x) ∂μ :=
let g := hfm.mk f in calc
∫ y, f y ∂(measure.map φ μ) = ∫ y, g y ∂(measure.map φ μ) : integral_congr_ae hfm.ae_eq_mk
... = ∫ x, g (φ x) ∂μ : integral_map_of_measurable hφ hfm.measurable_mk
... = ∫ x, f (φ x) ∂μ : integral_congr_ae $ ae_eq_comp hφ (hfm.ae_eq_mk).symm
lemma integral_map_of_closed_embedding {β} [topological_space α] [borel_space α]
[topological_space β] [measurable_space β] [borel_space β]
{φ : α → β} (hφ : closed_embedding φ) (f : β → E) :
∫ y, f y ∂(measure.map φ μ) = ∫ x, f (φ x) ∂μ :=
begin
by_cases hfm : ae_measurable f (measure.map φ μ),
{ exact integral_map hφ.continuous.measurable hfm },
{ rw [integral_non_ae_measurable hfm, integral_non_ae_measurable],
rwa ae_measurable_comp_right_iff_of_closed_embedding hφ }
end
lemma integral_dirac' (f : α → E) (a : α) (hfm : measurable f) :
∫ x, f x ∂(measure.dirac a) = f a :=
calc ∫ x, f x ∂(measure.dirac a) = ∫ x, f a ∂(measure.dirac a) :
integral_congr_ae $ ae_eq_dirac' hfm
... = f a : by simp [measure.dirac_apply_of_mem]
lemma integral_dirac [measurable_singleton_class α] (f : α → E) (a : α) :
∫ x, f x ∂(measure.dirac a) = f a :=
calc ∫ x, f x ∂(measure.dirac a) = ∫ x, f a ∂(measure.dirac a) :
integral_congr_ae $ ae_eq_dirac f
... = f a : by simp [measure.dirac_apply_of_mem]
end properties
section group
variables {G : Type*} [measurable_space G] [topological_space G] [group G] [has_continuous_mul G]
[borel_space G]
variables {μ : measure G}
open measure
/-- Translating a function by left-multiplication does not change its integral with respect to a
left-invariant measure. -/
@[to_additive]
lemma integral_mul_left_eq_self (hμ : is_mul_left_invariant μ) {f : G → E} (g : G) :
∫ x, f (g * x) ∂μ = ∫ x, f x ∂μ :=
begin
have hgμ : measure.map (has_mul.mul g) μ = μ,
{ rw ← map_mul_left_eq_self at hμ,
exact hμ g },
have h_mul : closed_embedding (λ x, g * x) := (homeomorph.mul_left g).closed_embedding,
rw [← integral_map_of_closed_embedding h_mul, hgμ]
end
/-- Translating a function by right-multiplication does not change its integral with respect to a
right-invariant measure. -/
@[to_additive]
lemma integral_mul_right_eq_self (hμ : is_mul_right_invariant μ) {f : G → E} (g : G) :
∫ x, f (x * g) ∂μ = ∫ x, f x ∂μ :=
begin
have hgμ : measure.map (λ x, x * g) μ = μ,
{ rw ← map_mul_right_eq_self at hμ,
exact hμ g },
have h_mul : closed_embedding (λ x, x * g) := (homeomorph.mul_right g).closed_embedding,
rw [← integral_map_of_closed_embedding h_mul, hgμ]
end
/-- If some left-translate of a function negates it, then the integral of the function with respect
to a left-invariant measure is 0. -/
@[to_additive]
lemma integral_zero_of_mul_left_eq_neg (hμ : is_mul_left_invariant μ) {f : G → E} {g : G}
(hf' : ∀ x, f (g * x) = - f x) :
∫ x, f x ∂μ = 0 :=
begin
refine eq_zero_of_eq_neg ℝ (eq.symm _),
have : ∫ x, f (g * x) ∂μ = ∫ x, - f x ∂μ,
{ congr,
ext x,
exact hf' x },
convert integral_mul_left_eq_self hμ g using 1,
rw [this, integral_neg]
end
/-- If some right-translate of a function negates it, then the integral of the function with respect
to a right-invariant measure is 0. -/
@[to_additive]
lemma integral_zero_of_mul_right_eq_neg (hμ : is_mul_right_invariant μ) {f : G → E} {g : G}
(hf' : ∀ x, f (x * g) = - f x) :
∫ x, f x ∂μ = 0 :=
begin
refine eq_zero_of_eq_neg ℝ (eq.symm _),
have : ∫ x, f (x * g) ∂μ = ∫ x, - f x ∂μ,
{ congr,
ext x,
exact hf' x },
convert integral_mul_right_eq_self hμ g using 1,
rw [this, integral_neg]
end
end group
mk_simp_attribute integral_simps "Simp set for integral rules."
attribute [integral_simps] integral_neg integral_smul L1.integral_add L1.integral_sub
L1.integral_smul L1.integral_neg
attribute [irreducible] integral L1.integral
section integral_trim
variables {H β γ : Type*} [normed_group H] [measurable_space H]
{m m0 : measurable_space β} {μ : measure β}
/-- Simple function seen as simple function of a larger `measurable_space`. -/
def simple_func.to_larger_space (hm : m ≤ m0) (f : @simple_func β m γ) : simple_func β γ :=
⟨@simple_func.to_fun β m γ f, λ x, hm _ (@simple_func.measurable_set_fiber β γ m f x),
@simple_func.finite_range β γ m f⟩
lemma simple_func.coe_to_larger_space_eq (hm : m ≤ m0) (f : @simple_func β m γ) :
⇑(f.to_larger_space hm) = f :=
rfl
lemma integral_simple_func_larger_space (hm : m ≤ m0) (f : @simple_func β m F)
(hf_int : integrable f μ) :
∫ x, f x ∂μ = ∑ x in (@simple_func.range β F m f), (ennreal.to_real (μ (f ⁻¹' {x}))) • x :=
begin
simp_rw ← f.coe_to_larger_space_eq hm,
have hf_int : integrable (f.to_larger_space hm) μ, by rwa simple_func.coe_to_larger_space_eq,
rw simple_func.integral_eq_sum _ hf_int,
congr,
end
lemma integral_trim_simple_func (hm : m ≤ m0) (f : @simple_func β m F) (hf_int : integrable f μ) :
∫ x, f x ∂μ = @integral β F m _ _ _ _ _ _ (μ.trim hm) f :=
begin
have hf : @measurable _ _ m _ f, from @simple_func.measurable β F m _ f,
have hf_int_m := hf_int.trim hm hf,
rw [integral_simple_func_larger_space le_rfl f hf_int_m,
integral_simple_func_larger_space hm f hf_int],
congr,
ext1 x,
congr,
exact (trim_measurable_set_eq hm (@simple_func.measurable_set_fiber β F m f x)).symm,
end
lemma integral_trim (hm : m ≤ m0) {f : β → F} (hf : @measurable β F m _ f) :
∫ x, f x ∂μ = @integral β F m _ _ _ _ _ _ (μ.trim hm) f :=
begin
by_cases hf_int : integrable f μ,
swap,
{ have hf_int_m : ¬ @integrable β F m _ _ f (μ.trim hm),
from λ hf_int_m, hf_int (integrable_of_integrable_trim hm hf_int_m),
rw [integral_undef hf_int, @integral_undef _ _ m _ _ _ _ _ _ _ _ hf_int_m], },
let f_seq := @simple_func.approx_on F β _ _ _ m _ hf set.univ 0 (set.mem_univ 0) _,
have hf_seq_meas : ∀ n, @measurable _ _ m _ (f_seq n),
from λ n, @simple_func.measurable β F m _ (f_seq n),
have hf_seq_int : ∀ n, integrable (f_seq n) μ,
from simple_func.integrable_approx_on_univ (hf.mono hm le_rfl) hf_int,
have hf_seq_int_m : ∀ n, @integrable β F m _ _ (f_seq n) (μ.trim hm),
from λ n, (hf_seq_int n).trim hm (hf_seq_meas n) ,
have hf_seq_eq : ∀ n, ∫ x, f_seq n x ∂μ = @integral β F m _ _ _ _ _ _ (μ.trim hm) (f_seq n),
from λ n, integral_trim_simple_func hm (f_seq n) (hf_seq_int n),
have h_lim_1 : at_top.tendsto (λ n, ∫ x, f_seq n x ∂μ) (𝓝 (∫ x, f x ∂μ)),
{ refine tendsto_integral_of_L1 f hf_int (eventually_of_forall hf_seq_int) _,
exact simple_func.tendsto_approx_on_univ_L1_edist (hf.mono hm le_rfl) hf_int, },
have h_lim_2 : at_top.tendsto (λ n, ∫ x, f_seq n x ∂μ)
(𝓝 (@integral β F m _ _ _ _ _ _ (μ.trim hm) f)),
{ simp_rw hf_seq_eq,
refine @tendsto_integral_of_L1 β F m _ _ _ _ _ _ (μ.trim hm) _ f
(hf_int.trim hm hf) _ _ (eventually_of_forall hf_seq_int_m) _,
exact @simple_func.tendsto_approx_on_univ_L1_edist β F m _ _ _ _ f _ hf (hf_int.trim hm hf), },
exact tendsto_nhds_unique h_lim_1 h_lim_2,
end
lemma integral_trim_ae (hm : m ≤ m0) {f : β → F} (hf : @ae_measurable β F m _ f (μ.trim hm)) :
∫ x, f x ∂μ = @integral β F m _ _ _ _ _ _ (μ.trim hm) f :=
begin
let f' := @ae_measurable.mk _ _ m _ _ f hf,
have hf'_eq_trim : f =ᶠ[@measure.ae _ m (μ.trim hm)] f',
from @ae_measurable.ae_eq_mk _ _ m _ f _ hf,
have hf'_eq : f =ᵐ[μ] f' := ae_eq_of_ae_eq_trim hf'_eq_trim,
rw [integral_congr_ae hf'_eq, @integral_congr_ae _ _ m _ _ _ _ _ _ _ _ _ hf'_eq_trim],
exact integral_trim hm (@ae_measurable.measurable_mk _ _ m _ f _ hf),
end
lemma ae_eq_trim_of_measurable [measurable_space γ] [add_group γ] [measurable_singleton_class γ]
[has_measurable_sub₂ γ]
(hm : m ≤ m0) {f g : β → γ} (hf : @measurable _ _ m _ f) (hg : @measurable _ _ m _ g)
(hfg : f =ᵐ[μ] g) :
f =ᶠ[@measure.ae β m (μ.trim hm)] g :=
begin
rwa [eventually_eq, ae_iff, trim_measurable_set_eq hm _],
exact (@measurable_set.compl β _ m (@measurable_set_eq_fun β m γ _ _ _ _ _ _ hf hg)),
end
lemma ae_eq_trim_iff [measurable_space γ] [add_group γ] [measurable_singleton_class γ]
[has_measurable_sub₂ γ]
(hm : m ≤ m0) {f g : β → γ} (hf : @measurable _ _ m _ f) (hg : @measurable _ _ m _ g) :
f =ᶠ[@measure.ae β m (μ.trim hm)] g ↔ f =ᵐ[μ] g :=
⟨ae_eq_of_ae_eq_trim, ae_eq_trim_of_measurable hm hf hg⟩
end integral_trim
end measure_theory
|
1b2b30b352b04a53feb4edb3ac469e746b7bda00 | 4bcaca5dc83d49803f72b7b5920b75b6e7d9de2d | /stage0/src/Lean/Elab/PreDefinition/Structural/Main.lean | b94d1149cfd1dd9ec96bf48dd681e2f35273828e | [
"Apache-2.0"
] | permissive | subfish-zhou/leanprover-zh_CN.github.io | 30b9fba9bd790720bd95764e61ae796697d2f603 | 8b2985d4a3d458ceda9361ac454c28168d920d3f | refs/heads/master | 1,689,709,967,820 | 1,632,503,056,000 | 1,632,503,056,000 | 409,962,097 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 4,205 | lean | /-
Copyright (c) 2021 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
import Lean.Elab.PreDefinition.Structural.Basic
import Lean.Elab.PreDefinition.Structural.FindRecArg
import Lean.Elab.PreDefinition.Structural.Preprocess
import Lean.Elab.PreDefinition.Structural.BRecOn
import Lean.Elab.PreDefinition.Structural.IndPred
import Lean.Elab.PreDefinition.Structural.Eqns
import Lean.Elab.PreDefinition.Structural.SmartUnfolding
namespace Lean.Elab
namespace Structural
open Meta
private def getFixedPrefix (declName : Name) (xs : Array Expr) (value : Expr) : MetaM Nat := do
let numFixedRef ← IO.mkRef xs.size
forEachExpr' value fun e => do
if e.isAppOf declName then
let args := e.getAppArgs
numFixedRef.modify fun numFixed => if args.size < numFixed then args.size else numFixed
for arg in args, x in xs do
/- We should not use structural equality here. For example, given the definition
```
def V.map {α β} f x x_1 :=
@V.map.match_1.{1} α (fun x x_2 => V β x) x x_1
(fun x x_2 => @V.mk₁ β x (f Bool.true x_2))
(fun e => @V.mk₂ β (V.map (fun b => α b) (fun b => β b) f Bool.false e))
```
The first three arguments at `V.map (fun b => α b) (fun b => β b) f Bool.false e` are "fixed"
modulo definitional equality.
We disable to proof irrelevance to be able to use structural recursion on inductive predicates.
For example, consider the example
```
inductive PList (α : Type) : Prop
| nil
| cons : α → PList α → PList α
infixr:67 " ::: " => PList.cons
set_option trace.Elab.definition.structural true in
def pmap {α β} (f : α → β) : PList α → PList β
| PList.nil => PList.nil
| a:::as => f a ::: pmap f as
```
The "Fixed" prefix would be 4 since all elements of type `PList α` are definitionally equal.
-/
if !(← withoutProofIrrelevance <| withReducible <| isDefEq arg x) then
-- We continue searching if e's arguments are not a prefix of `xs`
return true
return false
else
return true
numFixedRef.get
private def elimRecursion (preDef : PreDefinition) : M (Nat × PreDefinition) :=
withoutModifyingEnv do lambdaTelescope preDef.value fun xs value => do
addAsAxiom preDef
let value ← preprocess value preDef.declName
trace[Elab.definition.structural] "{preDef.declName} {xs} :=\n{value}"
let numFixed ← getFixedPrefix preDef.declName xs value
trace[Elab.definition.structural] "numFixed: {numFixed}"
findRecArg numFixed xs fun recArgInfo => do
-- when (recArgInfo.indName == `Nat) throwStructuralFailed -- HACK to skip Nat argument
let valueNew ←
if recArgInfo.indPred then mkIndPredBRecOn preDef.declName recArgInfo value
else mkBRecOn preDef.declName recArgInfo value
let valueNew ← mkLambdaFVars xs valueNew
trace[Elab.definition.structural] "result: {valueNew}"
-- Recursive applications may still occur in expressions that were not visited by replaceRecApps (e.g., in types)
let valueNew ← ensureNoRecFn preDef.declName valueNew
let recArgPos := recArgInfo.fixedParams.size + recArgInfo.pos
return (recArgPos, { preDef with value := valueNew })
def structuralRecursion (preDefs : Array PreDefinition) : TermElabM Unit :=
if preDefs.size != 1 then
throwError "structural recursion does not handle mutually recursive functions"
else do
let ((recArgPos, preDefNonRec), state) ← run <| elimRecursion preDefs[0]
state.addMatchers.forM liftM
mapError (addNonRec preDefNonRec) (fun msg => m!"structural recursion failed, produced type incorrect term{indentD msg}")
addAndCompilePartialRec preDefs
addSmartUnfoldingDef preDefs[0] recArgPos
registerEqnsInfo preDefs[0] recArgPos
builtin_initialize
registerTraceClass `Elab.definition.structural
end Structural
export Structural (structuralRecursion)
end Lean.Elab
|
2fd25efb1038319d7f49613e76f4c0b33a9ddba7 | 4d2583807a5ac6caaffd3d7a5f646d61ca85d532 | /src/analysis/normed_space/multilinear.lean | 26564838a5f6dff6196501fa58e2918adc88f305 | [
"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 | 73,355 | 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 analysis.normed_space.operator_norm
import topology.algebra.multilinear
/-!
# Operator norm on the space of continuous multilinear maps
When `f` is a continuous multilinear map in finitely many variables, we define its norm `∥f∥` as the
smallest number such that `∥f m∥ ≤ ∥f∥ * ∏ i, ∥m i∥` for all `m`.
We show that it is indeed a norm, and prove its basic properties.
## Main results
Let `f` be a multilinear map in finitely many variables.
* `exists_bound_of_continuous` asserts that, if `f` is continuous, then there exists `C > 0`
with `∥f m∥ ≤ C * ∏ i, ∥m i∥` for all `m`.
* `continuous_of_bound`, conversely, asserts that this bound implies continuity.
* `mk_continuous` constructs the associated continuous multilinear map.
Let `f` be a continuous multilinear map in finitely many variables.
* `∥f∥` is its norm, i.e., the smallest number such that `∥f m∥ ≤ ∥f∥ * ∏ i, ∥m i∥` for
all `m`.
* `le_op_norm f m` asserts the fundamental inequality `∥f m∥ ≤ ∥f∥ * ∏ i, ∥m i∥`.
* `norm_image_sub_le f m₁ m₂` gives a control of the difference `f m₁ - f m₂` in terms of
`∥f∥` and `∥m₁ - m₂∥`.
We also register isomorphisms corresponding to currying or uncurrying variables, transforming a
continuous multilinear function `f` in `n+1` variables into a continuous linear function taking
values in continuous multilinear functions in `n` variables, and also into a continuous multilinear
function in `n` variables taking values in continuous linear functions. These operations are called
`f.curry_left` and `f.curry_right` respectively (with inverses `f.uncurry_left` and
`f.uncurry_right`). They induce continuous linear equivalences between spaces of
continuous multilinear functions in `n+1` variables and spaces of continuous linear functions into
continuous multilinear functions in `n` variables (resp. continuous multilinear functions in `n`
variables taking values in continuous linear functions), called respectively
`continuous_multilinear_curry_left_equiv` and `continuous_multilinear_curry_right_equiv`.
## Implementation notes
We mostly follow the API (and the proofs) of `operator_norm.lean`, with the additional complexity
that we should deal with multilinear maps in several variables. The currying/uncurrying
constructions are based on those in `multilinear.lean`.
From the mathematical point of view, all the results follow from the results on operator norm in
one variable, by applying them to one variable after the other through currying. However, this
is only well defined when there is an order on the variables (for instance on `fin n`) although
the final result is independent of the order. While everything could be done following this
approach, it turns out that direct proofs are easier and more efficient.
-/
noncomputable theory
open_locale classical big_operators nnreal
open finset metric
local attribute [instance, priority 1001]
add_comm_group.to_add_comm_monoid normed_group.to_add_comm_group normed_space.to_module
-- hack to speed up simp when dealing with complicated types
local attribute [-instance] unique.subsingleton pi.subsingleton
/-!
### Type variables
We use the following type variables in this file:
* `𝕜` : a `nondiscrete_normed_field`;
* `ι`, `ι'` : finite index types with decidable equality;
* `E`, `E₁` : families of normed vector spaces over `𝕜` indexed by `i : ι`;
* `E'` : a family of normed vector spaces over `𝕜` indexed by `i' : ι'`;
* `Ei` : a family of normed vector spaces over `𝕜` indexed by `i : fin (nat.succ n)`;
* `G`, `G'` : normed vector spaces over `𝕜`.
-/
universes u v v' wE wE₁ wE' wEi wG wG'
variables {𝕜 : Type u} {ι : Type v} {ι' : Type v'} {n : ℕ}
{E : ι → Type wE} {E₁ : ι → Type wE₁} {E' : ι' → Type wE'} {Ei : fin n.succ → Type wEi}
{G : Type wG} {G' : Type wG'}
[decidable_eq ι] [fintype ι] [decidable_eq ι'] [fintype ι'] [nondiscrete_normed_field 𝕜]
[Π i, normed_group (E i)] [Π i, normed_space 𝕜 (E i)]
[Π i, normed_group (E₁ i)] [Π i, normed_space 𝕜 (E₁ i)]
[Π i, normed_group (E' i)] [Π i, normed_space 𝕜 (E' i)]
[Π i, normed_group (Ei i)] [Π i, normed_space 𝕜 (Ei i)]
[normed_group G] [normed_space 𝕜 G] [normed_group G'] [normed_space 𝕜 G']
/-!
### Continuity properties of multilinear maps
We relate continuity of multilinear maps to the inequality `∥f m∥ ≤ C * ∏ i, ∥m i∥`, in
both directions. Along the way, we prove useful bounds on the difference `∥f m₁ - f m₂∥`.
-/
namespace multilinear_map
variable (f : multilinear_map 𝕜 E G)
/-- If a multilinear map in finitely many variables on normed spaces satisfies the inequality
`∥f m∥ ≤ C * ∏ i, ∥m i∥` on a shell `ε i / ∥c i∥ < ∥m i∥ < ε i` for some positive numbers `ε i`
and elements `c i : 𝕜`, `1 < ∥c i∥`, then it satisfies this inequality for all `m`. -/
lemma bound_of_shell {ε : ι → ℝ} {C : ℝ} (hε : ∀ i, 0 < ε i) {c : ι → 𝕜} (hc : ∀ i, 1 < ∥c i∥)
(hf : ∀ m : Π i, E i, (∀ i, ε i / ∥c i∥ ≤ ∥m i∥) → (∀ i, ∥m i∥ < ε i) → ∥f m∥ ≤ C * ∏ i, ∥m i∥)
(m : Π i, E i) : ∥f m∥ ≤ C * ∏ i, ∥m i∥ :=
begin
rcases em (∃ i, m i = 0) with ⟨i, hi⟩|hm; [skip, push_neg at hm],
{ simp [f.map_coord_zero i hi, prod_eq_zero (mem_univ i), hi] },
choose δ hδ0 hδm_lt hle_δm hδinv using λ i, rescale_to_shell (hc i) (hε i) (hm i),
have hδ0 : 0 < ∏ i, ∥δ i∥, from prod_pos (λ i _, norm_pos_iff.2 (hδ0 i)),
simpa [map_smul_univ, norm_smul, prod_mul_distrib, mul_left_comm C, mul_le_mul_left hδ0]
using hf (λ i, δ i • m i) hle_δm hδm_lt,
end
/-- If a multilinear map in finitely many variables on normed spaces is continuous, then it
satisfies the inequality `∥f m∥ ≤ C * ∏ i, ∥m i∥`, for some `C` which can be chosen to be
positive. -/
theorem exists_bound_of_continuous (hf : continuous f) :
∃ (C : ℝ), 0 < C ∧ (∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) :=
begin
casesI is_empty_or_nonempty ι,
{ refine ⟨∥f 0∥ + 1, add_pos_of_nonneg_of_pos (norm_nonneg _) zero_lt_one, λ m, _⟩,
obtain rfl : m = 0, from funext (is_empty.elim ‹_›),
simp [univ_eq_empty, zero_le_one] },
obtain ⟨ε : ℝ, ε0 : 0 < ε, hε : ∀ m : Π i, E i, ∥m - 0∥ < ε → ∥f m - f 0∥ < 1⟩ :=
normed_group.tendsto_nhds_nhds.1 (hf.tendsto 0) 1 zero_lt_one,
simp only [sub_zero, f.map_zero] at hε,
rcases normed_field.exists_one_lt_norm 𝕜 with ⟨c, hc⟩,
have : 0 < (∥c∥ / ε) ^ fintype.card ι, from pow_pos (div_pos (zero_lt_one.trans hc) ε0) _,
refine ⟨_, this, _⟩,
refine f.bound_of_shell (λ _, ε0) (λ _, hc) (λ m hcm hm, _),
refine (hε m ((pi_norm_lt_iff ε0).2 hm)).le.trans _,
rw [← div_le_iff' this, one_div, ← inv_pow₀, inv_div, fintype.card, ← prod_const],
exact prod_le_prod (λ _ _, div_nonneg ε0.le (norm_nonneg _)) (λ i _, hcm i)
end
/-- If `f` satisfies a boundedness property around `0`, one can deduce a bound on `f m₁ - f m₂`
using the multilinearity. Here, we give a precise but hard to use version. See
`norm_image_sub_le_of_bound` for a less precise but more usable version. The bound reads
`∥f m - f m'∥ ≤
C * ∥m 1 - m' 1∥ * max ∥m 2∥ ∥m' 2∥ * max ∥m 3∥ ∥m' 3∥ * ... * max ∥m n∥ ∥m' n∥ + ...`,
where the other terms in the sum are the same products where `1` is replaced by any `i`. -/
lemma norm_image_sub_le_of_bound' {C : ℝ} (hC : 0 ≤ C)
(H : ∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) (m₁ m₂ : Πi, E i) :
∥f m₁ - f m₂∥ ≤
C * ∑ i, ∏ j, if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥ :=
begin
have A : ∀(s : finset ι), ∥f m₁ - f (s.piecewise m₂ m₁)∥
≤ C * ∑ i in s, ∏ j, if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥,
{ refine finset.induction (by simp) _,
assume i s his Hrec,
have I : ∥f (s.piecewise m₂ m₁) - f ((insert i s).piecewise m₂ m₁)∥
≤ C * ∏ j, if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥,
{ have A : ((insert i s).piecewise m₂ m₁)
= function.update (s.piecewise m₂ m₁) i (m₂ i) := s.piecewise_insert _ _ _,
have B : s.piecewise m₂ m₁ = function.update (s.piecewise m₂ m₁) i (m₁ i),
{ ext j,
by_cases h : j = i,
{ rw h, simp [his] },
{ simp [h] } },
rw [B, A, ← f.map_sub],
apply le_trans (H _) (mul_le_mul_of_nonneg_left _ hC),
refine prod_le_prod (λj hj, norm_nonneg _) (λj hj, _),
by_cases h : j = i,
{ rw h, simp },
{ by_cases h' : j ∈ s;
simp [h', h, le_refl] } },
calc ∥f m₁ - f ((insert i s).piecewise m₂ m₁)∥ ≤
∥f m₁ - f (s.piecewise m₂ m₁)∥ + ∥f (s.piecewise m₂ m₁) - f ((insert i s).piecewise m₂ m₁)∥ :
by { rw [← dist_eq_norm, ← dist_eq_norm, ← dist_eq_norm], exact dist_triangle _ _ _ }
... ≤ (C * ∑ i in s, ∏ j, if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥)
+ C * ∏ j, if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥ :
add_le_add Hrec I
... = C * ∑ i in insert i s, ∏ j, if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥ :
by simp [his, add_comm, left_distrib] },
convert A univ,
simp
end
/-- If `f` satisfies a boundedness property around `0`, one can deduce a bound on `f m₁ - f m₂`
using the multilinearity. Here, we give a usable but not very precise version. See
`norm_image_sub_le_of_bound'` for a more precise but less usable version. The bound is
`∥f m - f m'∥ ≤ C * card ι * ∥m - m'∥ * (max ∥m∥ ∥m'∥) ^ (card ι - 1)`. -/
lemma norm_image_sub_le_of_bound {C : ℝ} (hC : 0 ≤ C)
(H : ∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) (m₁ m₂ : Πi, E i) :
∥f m₁ - f m₂∥ ≤ C * (fintype.card ι) * (max ∥m₁∥ ∥m₂∥) ^ (fintype.card ι - 1) * ∥m₁ - m₂∥ :=
begin
have A : ∀ (i : ι), ∏ j, (if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥)
≤ ∥m₁ - m₂∥ * (max ∥m₁∥ ∥m₂∥) ^ (fintype.card ι - 1),
{ assume i,
calc ∏ j, (if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥)
≤ ∏ j : ι, function.update (λ j, max ∥m₁∥ ∥m₂∥) i (∥m₁ - m₂∥) j :
begin
apply prod_le_prod,
{ assume j hj, by_cases h : j = i; simp [h, norm_nonneg] },
{ assume j hj,
by_cases h : j = i,
{ rw h, simp, exact norm_le_pi_norm (m₁ - m₂) i },
{ simp [h, max_le_max, norm_le_pi_norm] } }
end
... = ∥m₁ - m₂∥ * (max ∥m₁∥ ∥m₂∥) ^ (fintype.card ι - 1) :
by { rw prod_update_of_mem (finset.mem_univ _), simp [card_univ_diff] } },
calc
∥f m₁ - f m₂∥
≤ C * ∑ i, ∏ j, if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥ :
f.norm_image_sub_le_of_bound' hC H m₁ m₂
... ≤ C * ∑ i, ∥m₁ - m₂∥ * (max ∥m₁∥ ∥m₂∥) ^ (fintype.card ι - 1) :
mul_le_mul_of_nonneg_left (sum_le_sum (λi hi, A i)) hC
... = C * (fintype.card ι) * (max ∥m₁∥ ∥m₂∥) ^ (fintype.card ι - 1) * ∥m₁ - m₂∥ :
by { rw [sum_const, card_univ, nsmul_eq_mul], ring }
end
/-- If a multilinear map satisfies an inequality `∥f m∥ ≤ C * ∏ i, ∥m i∥`, then it is
continuous. -/
theorem continuous_of_bound (C : ℝ) (H : ∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) :
continuous f :=
begin
let D := max C 1,
have D_pos : 0 ≤ D := le_trans zero_le_one (le_max_right _ _),
replace H : ∀ m, ∥f m∥ ≤ D * ∏ i, ∥m i∥,
{ assume m,
apply le_trans (H m) (mul_le_mul_of_nonneg_right (le_max_left _ _) _),
exact prod_nonneg (λ(i : ι) hi, norm_nonneg (m i)) },
refine continuous_iff_continuous_at.2 (λm, _),
refine continuous_at_of_locally_lipschitz zero_lt_one
(D * (fintype.card ι) * (∥m∥ + 1) ^ (fintype.card ι - 1)) (λm' h', _),
rw [dist_eq_norm, dist_eq_norm],
have : 0 ≤ (max ∥m'∥ ∥m∥), by simp,
have : (max ∥m'∥ ∥m∥) ≤ ∥m∥ + 1,
by simp [zero_le_one, norm_le_of_mem_closed_ball (le_of_lt h'), -add_comm],
calc
∥f m' - f m∥
≤ D * (fintype.card ι) * (max ∥m'∥ ∥m∥) ^ (fintype.card ι - 1) * ∥m' - m∥ :
f.norm_image_sub_le_of_bound D_pos H m' m
... ≤ D * (fintype.card ι) * (∥m∥ + 1) ^ (fintype.card ι - 1) * ∥m' - m∥ :
by apply_rules [mul_le_mul_of_nonneg_right, mul_le_mul_of_nonneg_left, mul_nonneg,
norm_nonneg, nat.cast_nonneg, pow_le_pow_of_le_left]
end
/-- Constructing a continuous multilinear map from a multilinear map satisfying a boundedness
condition. -/
def mk_continuous (C : ℝ) (H : ∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) :
continuous_multilinear_map 𝕜 E G :=
{ cont := f.continuous_of_bound C H, ..f }
@[simp] lemma coe_mk_continuous (C : ℝ) (H : ∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) :
⇑(f.mk_continuous C H) = f :=
rfl
/-- Given a multilinear map in `n` variables, if one restricts it to `k` variables putting `z` on
the other coordinates, then the resulting restricted function satisfies an inequality
`∥f.restr v∥ ≤ C * ∥z∥^(n-k) * Π ∥v i∥` if the original function satisfies `∥f v∥ ≤ C * Π ∥v i∥`. -/
lemma restr_norm_le {k n : ℕ} (f : (multilinear_map 𝕜 (λ i : fin n, G) G' : _))
(s : finset (fin n)) (hk : s.card = k) (z : G) {C : ℝ}
(H : ∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) (v : fin k → G) :
∥f.restr s hk z v∥ ≤ C * ∥z∥ ^ (n - k) * ∏ i, ∥v i∥ :=
begin
rw [mul_right_comm, mul_assoc],
convert H _ using 2,
simp only [apply_dite norm, fintype.prod_dite, prod_const (∥z∥), finset.card_univ,
fintype.card_of_subtype sᶜ (λ x, mem_compl), card_compl, fintype.card_fin, hk, mk_coe,
← (s.order_iso_of_fin hk).symm.bijective.prod_comp (λ x, ∥v x∥)],
refl
end
end multilinear_map
/-!
### Continuous multilinear maps
We define the norm `∥f∥` of a continuous multilinear map `f` in finitely many variables as the
smallest number such that `∥f m∥ ≤ ∥f∥ * ∏ i, ∥m i∥` for all `m`. We show that this
defines a normed space structure on `continuous_multilinear_map 𝕜 E G`.
-/
namespace continuous_multilinear_map
variables (c : 𝕜) (f g : continuous_multilinear_map 𝕜 E G) (m : Πi, E i)
theorem bound : ∃ (C : ℝ), 0 < C ∧ (∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) :=
f.to_multilinear_map.exists_bound_of_continuous f.2
open real
/-- The operator norm of a continuous multilinear map is the inf of all its bounds. -/
def op_norm := Inf {c | 0 ≤ (c : ℝ) ∧ ∀ m, ∥f m∥ ≤ c * ∏ i, ∥m i∥}
instance has_op_norm : has_norm (continuous_multilinear_map 𝕜 E G) := ⟨op_norm⟩
lemma norm_def : ∥f∥ = Inf {c | 0 ≤ (c : ℝ) ∧ ∀ m, ∥f m∥ ≤ c * ∏ i, ∥m i∥} := rfl
-- So that invocations of `le_cInf` make sense: we show that the set of
-- bounds is nonempty and bounded below.
lemma bounds_nonempty {f : continuous_multilinear_map 𝕜 E G} :
∃ c, c ∈ {c | 0 ≤ c ∧ ∀ m, ∥f m∥ ≤ c * ∏ i, ∥m i∥} :=
let ⟨M, hMp, hMb⟩ := f.bound in ⟨M, le_of_lt hMp, hMb⟩
lemma bounds_bdd_below {f : continuous_multilinear_map 𝕜 E G} :
bdd_below {c | 0 ≤ c ∧ ∀ m, ∥f m∥ ≤ c * ∏ i, ∥m i∥} :=
⟨0, λ _ ⟨hn, _⟩, hn⟩
lemma op_norm_nonneg : 0 ≤ ∥f∥ :=
le_cInf bounds_nonempty (λ _ ⟨hx, _⟩, hx)
/-- The fundamental property of the operator norm of a continuous multilinear map:
`∥f m∥` is bounded by `∥f∥` times the product of the `∥m i∥`. -/
theorem le_op_norm : ∥f m∥ ≤ ∥f∥ * ∏ i, ∥m i∥ :=
begin
have A : 0 ≤ ∏ i, ∥m i∥ := prod_nonneg (λj hj, norm_nonneg _),
cases A.eq_or_lt with h hlt,
{ rcases prod_eq_zero_iff.1 h.symm with ⟨i, _, hi⟩,
rw norm_eq_zero at hi,
have : f m = 0 := f.map_coord_zero i hi,
rw [this, norm_zero],
exact mul_nonneg (op_norm_nonneg f) A },
{ rw [← div_le_iff hlt],
apply le_cInf bounds_nonempty,
rintro c ⟨_, hc⟩, rw [div_le_iff hlt], apply hc }
end
theorem le_of_op_norm_le {C : ℝ} (h : ∥f∥ ≤ C) : ∥f m∥ ≤ C * ∏ i, ∥m i∥ :=
(f.le_op_norm m).trans $ mul_le_mul_of_nonneg_right h (prod_nonneg $ λ i _, norm_nonneg (m i))
lemma ratio_le_op_norm : ∥f m∥ / ∏ i, ∥m i∥ ≤ ∥f∥ :=
div_le_of_nonneg_of_le_mul (prod_nonneg $ λ i _, norm_nonneg _) (op_norm_nonneg _) (f.le_op_norm m)
/-- The image of the unit ball under a continuous multilinear map is bounded. -/
lemma unit_le_op_norm (h : ∥m∥ ≤ 1) : ∥f m∥ ≤ ∥f∥ :=
calc
∥f m∥ ≤ ∥f∥ * ∏ i, ∥m i∥ : f.le_op_norm m
... ≤ ∥f∥ * ∏ i : ι, 1 :
mul_le_mul_of_nonneg_left (prod_le_prod (λi hi, norm_nonneg _)
(λi hi, le_trans (norm_le_pi_norm _ _) h)) (op_norm_nonneg f)
... = ∥f∥ : by simp
/-- If one controls the norm of every `f x`, then one controls the norm of `f`. -/
lemma op_norm_le_bound {M : ℝ} (hMp: 0 ≤ M) (hM : ∀ m, ∥f m∥ ≤ M * ∏ i, ∥m i∥) :
∥f∥ ≤ M :=
cInf_le bounds_bdd_below ⟨hMp, hM⟩
/-- The operator norm satisfies the triangle inequality. -/
theorem op_norm_add_le : ∥f + g∥ ≤ ∥f∥ + ∥g∥ :=
cInf_le bounds_bdd_below
⟨add_nonneg (op_norm_nonneg _) (op_norm_nonneg _), λ x, by { rw add_mul,
exact norm_add_le_of_le (le_op_norm _ _) (le_op_norm _ _) }⟩
/-- A continuous linear map is zero iff its norm vanishes. -/
theorem op_norm_zero_iff : ∥f∥ = 0 ↔ f = 0 :=
begin
split,
{ assume h,
ext m,
simpa [h] using f.le_op_norm m },
{ rintro rfl,
apply le_antisymm (op_norm_le_bound 0 le_rfl (λm, _)) (op_norm_nonneg _),
simp }
end
variables {𝕜' : Type*} [nondiscrete_normed_field 𝕜'] [normed_algebra 𝕜' 𝕜]
[normed_space 𝕜' G] [is_scalar_tower 𝕜' 𝕜 G]
lemma op_norm_smul_le (c : 𝕜') : ∥c • f∥ ≤ ∥c∥ * ∥f∥ :=
(c • f).op_norm_le_bound
(mul_nonneg (norm_nonneg _) (op_norm_nonneg _))
begin
intro m,
erw [norm_smul, mul_assoc],
exact mul_le_mul_of_nonneg_left (le_op_norm _ _) (norm_nonneg _)
end
lemma op_norm_neg : ∥-f∥ = ∥f∥ := by { rw norm_def, apply congr_arg, ext, simp }
/-- Continuous multilinear maps themselves form a normed space with respect to
the operator norm. -/
instance to_normed_group : normed_group (continuous_multilinear_map 𝕜 E G) :=
normed_group.of_core _ ⟨op_norm_zero_iff, op_norm_add_le, op_norm_neg⟩
instance to_normed_space : normed_space 𝕜' (continuous_multilinear_map 𝕜 E G) :=
⟨λ c f, f.op_norm_smul_le c⟩
theorem le_op_norm_mul_prod_of_le {b : ι → ℝ} (hm : ∀ i, ∥m i∥ ≤ b i) : ∥f m∥ ≤ ∥f∥ * ∏ i, b i :=
(f.le_op_norm m).trans $ mul_le_mul_of_nonneg_left
(prod_le_prod (λ _ _, norm_nonneg _) (λ i _, hm i)) (norm_nonneg f)
theorem le_op_norm_mul_pow_card_of_le {b : ℝ} (hm : ∀ i, ∥m i∥ ≤ b) :
∥f m∥ ≤ ∥f∥ * b ^ fintype.card ι :=
by simpa only [prod_const] using f.le_op_norm_mul_prod_of_le m hm
theorem le_op_norm_mul_pow_of_le {Ei : fin n → Type*} [Π i, normed_group (Ei i)]
[Π i, normed_space 𝕜 (Ei i)] (f : continuous_multilinear_map 𝕜 Ei G) (m : Π i, Ei i)
{b : ℝ} (hm : ∥m∥ ≤ b) :
∥f m∥ ≤ ∥f∥ * b ^ n :=
by simpa only [fintype.card_fin]
using f.le_op_norm_mul_pow_card_of_le m (λ i, (norm_le_pi_norm m i).trans hm)
/-- The fundamental property of the operator norm of a continuous multilinear map:
`∥f m∥` is bounded by `∥f∥` times the product of the `∥m i∥`, `nnnorm` version. -/
theorem le_op_nnnorm : nnnorm (f m) ≤ nnnorm f * ∏ i, nnnorm (m i) :=
nnreal.coe_le_coe.1 $ by { push_cast, exact f.le_op_norm m }
theorem le_of_op_nnnorm_le {C : ℝ≥0} (h : nnnorm f ≤ C) : nnnorm (f m) ≤ C * ∏ i, nnnorm (m i) :=
(f.le_op_nnnorm m).trans $ mul_le_mul' h le_rfl
lemma op_norm_prod (f : continuous_multilinear_map 𝕜 E G) (g : continuous_multilinear_map 𝕜 E G') :
∥f.prod g∥ = max (∥f∥) (∥g∥) :=
le_antisymm
(op_norm_le_bound _ (norm_nonneg (f, g)) (λ m,
have H : 0 ≤ ∏ i, ∥m i∥, from prod_nonneg $ λ _ _, norm_nonneg _,
by simpa only [prod_apply, prod.norm_def, max_mul_of_nonneg, H]
using max_le_max (f.le_op_norm m) (g.le_op_norm m))) $
max_le
(f.op_norm_le_bound (norm_nonneg _) $ λ m, (le_max_left _ _).trans ((f.prod g).le_op_norm _))
(g.op_norm_le_bound (norm_nonneg _) $ λ m, (le_max_right _ _).trans ((f.prod g).le_op_norm _))
lemma norm_pi {ι' : Type v'} [fintype ι'] {E' : ι' → Type wE'} [Π i', normed_group (E' i')]
[Π i', normed_space 𝕜 (E' i')] (f : Π i', continuous_multilinear_map 𝕜 E (E' i')) :
∥pi f∥ = ∥f∥ :=
begin
apply le_antisymm,
{ refine (op_norm_le_bound _ (norm_nonneg f) (λ m, _)),
dsimp,
rw pi_norm_le_iff,
exacts [λ i, (f i).le_of_op_norm_le m (norm_le_pi_norm f i),
mul_nonneg (norm_nonneg f) (prod_nonneg $ λ _ _, norm_nonneg _)] },
{ refine (pi_norm_le_iff (norm_nonneg _)).2 (λ i, _),
refine (op_norm_le_bound _ (norm_nonneg _) (λ m, _)),
refine le_trans _ ((pi f).le_op_norm m),
convert norm_le_pi_norm (λ j, f j m) i }
end
section
variables (𝕜 E E' G G')
/-- `continuous_multilinear_map.prod` as a `linear_isometry_equiv`. -/
def prodL :
(continuous_multilinear_map 𝕜 E G) × (continuous_multilinear_map 𝕜 E G') ≃ₗᵢ[𝕜]
continuous_multilinear_map 𝕜 E (G × G') :=
{ to_fun := λ f, f.1.prod f.2,
inv_fun := λ f, ((continuous_linear_map.fst 𝕜 G G').comp_continuous_multilinear_map f,
(continuous_linear_map.snd 𝕜 G G').comp_continuous_multilinear_map f),
map_add' := λ f g, rfl,
map_smul' := λ c f, rfl,
left_inv := λ f, by ext; refl,
right_inv := λ f, by ext; refl,
norm_map' := λ f, op_norm_prod f.1 f.2 }
/-- `continuous_multilinear_map.pi` as a `linear_isometry_equiv`. -/
def piₗᵢ {ι' : Type v'} [fintype ι'] {E' : ι' → Type wE'} [Π i', normed_group (E' i')]
[Π i', normed_space 𝕜 (E' i')] :
@linear_isometry_equiv 𝕜 𝕜 _ _ (ring_hom.id 𝕜) _ _ _
(Π i', continuous_multilinear_map 𝕜 E (E' i')) (continuous_multilinear_map 𝕜 E (Π i, E' i)) _ _
(@pi.module ι' _ 𝕜 _ _ (λ i', infer_instance)) _ :=
{ to_linear_equiv :=
-- note: `pi_linear_equiv` does not unify correctly here, presumably due to issues with dependent
-- typeclass arguments.
{ map_add' := λ f g, rfl,
map_smul' := λ c f, rfl,
.. pi_equiv, },
norm_map' := norm_pi }
end
section restrict_scalars
variables [Π i, normed_space 𝕜' (E i)] [∀ i, is_scalar_tower 𝕜' 𝕜 (E i)]
@[simp] lemma norm_restrict_scalars : ∥f.restrict_scalars 𝕜'∥ = ∥f∥ :=
by simp only [norm_def, coe_restrict_scalars]
variable (𝕜')
/-- `continuous_multilinear_map.restrict_scalars` as a `continuous_multilinear_map`. -/
def restrict_scalars_linear :
continuous_multilinear_map 𝕜 E G →L[𝕜'] continuous_multilinear_map 𝕜' E G :=
linear_map.mk_continuous
{ to_fun := restrict_scalars 𝕜',
map_add' := λ m₁ m₂, rfl,
map_smul' := λ c m, rfl } 1 $ λ f, by simp
variable {𝕜'}
lemma continuous_restrict_scalars :
continuous (restrict_scalars 𝕜' : continuous_multilinear_map 𝕜 E G →
continuous_multilinear_map 𝕜' E G) :=
(restrict_scalars_linear 𝕜').continuous
end restrict_scalars
/-- The difference `f m₁ - f m₂` is controlled in terms of `∥f∥` and `∥m₁ - m₂∥`, precise version.
For a less precise but more usable version, see `norm_image_sub_le`. The bound reads
`∥f m - f m'∥ ≤
∥f∥ * ∥m 1 - m' 1∥ * max ∥m 2∥ ∥m' 2∥ * max ∥m 3∥ ∥m' 3∥ * ... * max ∥m n∥ ∥m' n∥ + ...`,
where the other terms in the sum are the same products where `1` is replaced by any `i`.-/
lemma norm_image_sub_le' (m₁ m₂ : Πi, E i) :
∥f m₁ - f m₂∥ ≤
∥f∥ * ∑ i, ∏ j, if j = i then ∥m₁ i - m₂ i∥ else max ∥m₁ j∥ ∥m₂ j∥ :=
f.to_multilinear_map.norm_image_sub_le_of_bound' (norm_nonneg _) f.le_op_norm _ _
/-- The difference `f m₁ - f m₂` is controlled in terms of `∥f∥` and `∥m₁ - m₂∥`, less precise
version. For a more precise but less usable version, see `norm_image_sub_le'`.
The bound is `∥f m - f m'∥ ≤ ∥f∥ * card ι * ∥m - m'∥ * (max ∥m∥ ∥m'∥) ^ (card ι - 1)`.-/
lemma norm_image_sub_le (m₁ m₂ : Πi, E i) :
∥f m₁ - f m₂∥ ≤ ∥f∥ * (fintype.card ι) * (max ∥m₁∥ ∥m₂∥) ^ (fintype.card ι - 1) * ∥m₁ - m₂∥ :=
f.to_multilinear_map.norm_image_sub_le_of_bound (norm_nonneg _) f.le_op_norm _ _
/-- Applying a multilinear map to a vector is continuous in both coordinates. -/
lemma continuous_eval :
continuous (λ p : continuous_multilinear_map 𝕜 E G × Π i, E i, p.1 p.2) :=
begin
apply continuous_iff_continuous_at.2 (λp, _),
apply continuous_at_of_locally_lipschitz zero_lt_one
((∥p∥ + 1) * (fintype.card ι) * (∥p∥ + 1) ^ (fintype.card ι - 1) + ∏ i, ∥p.2 i∥)
(λq hq, _),
have : 0 ≤ (max ∥q.2∥ ∥p.2∥), by simp,
have : 0 ≤ ∥p∥ + 1, by simp [le_trans zero_le_one],
have A : ∥q∥ ≤ ∥p∥ + 1 := norm_le_of_mem_closed_ball (le_of_lt hq),
have : (max ∥q.2∥ ∥p.2∥) ≤ ∥p∥ + 1 :=
le_trans (max_le_max (norm_snd_le q) (norm_snd_le p)) (by simp [A, -add_comm, zero_le_one]),
have : ∀ (i : ι), i ∈ univ → 0 ≤ ∥p.2 i∥ := λ i hi, norm_nonneg _,
calc dist (q.1 q.2) (p.1 p.2)
≤ dist (q.1 q.2) (q.1 p.2) + dist (q.1 p.2) (p.1 p.2) : dist_triangle _ _ _
... = ∥q.1 q.2 - q.1 p.2∥ + ∥q.1 p.2 - p.1 p.2∥ : by rw [dist_eq_norm, dist_eq_norm]
... ≤ ∥q.1∥ * (fintype.card ι) * (max ∥q.2∥ ∥p.2∥) ^ (fintype.card ι - 1) * ∥q.2 - p.2∥
+ ∥q.1 - p.1∥ * ∏ i, ∥p.2 i∥ :
add_le_add (norm_image_sub_le _ _ _) ((q.1 - p.1).le_op_norm p.2)
... ≤ (∥p∥ + 1) * (fintype.card ι) * (∥p∥ + 1) ^ (fintype.card ι - 1) * ∥q - p∥
+ ∥q - p∥ * ∏ i, ∥p.2 i∥ :
by apply_rules [add_le_add, mul_le_mul, le_refl, le_trans (norm_fst_le q) A, nat.cast_nonneg,
mul_nonneg, pow_le_pow_of_le_left, pow_nonneg, norm_snd_le (q - p), norm_nonneg,
norm_fst_le (q - p), prod_nonneg]
... = ((∥p∥ + 1) * (fintype.card ι) * (∥p∥ + 1) ^ (fintype.card ι - 1)
+ (∏ i, ∥p.2 i∥)) * dist q p : by { rw dist_eq_norm, ring }
end
lemma continuous_eval_left (m : Π i, E i) :
continuous (λ p : continuous_multilinear_map 𝕜 E G, p m) :=
continuous_eval.comp (continuous_id.prod_mk continuous_const)
lemma has_sum_eval
{α : Type*} {p : α → continuous_multilinear_map 𝕜 E G} {q : continuous_multilinear_map 𝕜 E G}
(h : has_sum p q) (m : Π i, E i) : has_sum (λ a, p a m) (q m) :=
begin
dsimp [has_sum] at h ⊢,
convert ((continuous_eval_left m).tendsto _).comp h,
ext s,
simp
end
lemma tsum_eval {α : Type*} {p : α → continuous_multilinear_map 𝕜 E G} (hp : summable p)
(m : Π i, E i) : (∑' a, p a) m = ∑' a, p a m :=
(has_sum_eval hp.has_sum m).tsum_eq.symm
open_locale topological_space
open filter
/-- If the target space is complete, the space of continuous multilinear maps with its norm is also
complete. The proof is essentially the same as for the space of continuous linear maps (modulo the
addition of `finset.prod` where needed. The duplication could be avoided by deducing the linear
case from the multilinear case via a currying isomorphism. However, this would mess up imports,
and it is more satisfactory to have the simplest case as a standalone proof. -/
instance [complete_space G] : complete_space (continuous_multilinear_map 𝕜 E G) :=
begin
have nonneg : ∀ (v : Π i, E i), 0 ≤ ∏ i, ∥v i∥ :=
λ v, finset.prod_nonneg (λ i hi, norm_nonneg _),
-- We show that every Cauchy sequence converges.
refine metric.complete_of_cauchy_seq_tendsto (λ f hf, _),
-- We now expand out the definition of a Cauchy sequence,
rcases cauchy_seq_iff_le_tendsto_0.1 hf with ⟨b, b0, b_bound, b_lim⟩,
-- and establish that the evaluation at any point `v : Π i, E i` is Cauchy.
have cau : ∀ v, cauchy_seq (λ n, f n v),
{ assume v,
apply cauchy_seq_iff_le_tendsto_0.2 ⟨λ n, b n * ∏ i, ∥v i∥, λ n, _, _, _⟩,
{ exact mul_nonneg (b0 n) (nonneg v) },
{ assume n m N hn hm,
rw dist_eq_norm,
apply le_trans ((f n - f m).le_op_norm v) _,
exact mul_le_mul_of_nonneg_right (b_bound n m N hn hm) (nonneg v) },
{ simpa using b_lim.mul tendsto_const_nhds } },
-- We assemble the limits points of those Cauchy sequences
-- (which exist as `G` is complete)
-- into a function which we call `F`.
choose F hF using λv, cauchy_seq_tendsto_of_complete (cau v),
-- Next, we show that this `F` is multilinear,
let Fmult : multilinear_map 𝕜 E G :=
{ to_fun := F,
map_add' := λ v i x y, begin
have A := hF (function.update v i (x + y)),
have B := (hF (function.update v i x)).add (hF (function.update v i y)),
simp at A B,
exact tendsto_nhds_unique A B
end,
map_smul' := λ v i c x, begin
have A := hF (function.update v i (c • x)),
have B := filter.tendsto.smul (@tendsto_const_nhds _ ℕ _ c _) (hF (function.update v i x)),
simp at A B,
exact tendsto_nhds_unique A B
end },
-- and that `F` has norm at most `(b 0 + ∥f 0∥)`.
have Fnorm : ∀ v, ∥F v∥ ≤ (b 0 + ∥f 0∥) * ∏ i, ∥v i∥,
{ assume v,
have A : ∀ n, ∥f n v∥ ≤ (b 0 + ∥f 0∥) * ∏ i, ∥v i∥,
{ assume n,
apply le_trans ((f n).le_op_norm _) _,
apply mul_le_mul_of_nonneg_right _ (nonneg v),
calc ∥f n∥ = ∥(f n - f 0) + f 0∥ : by { congr' 1, abel }
... ≤ ∥f n - f 0∥ + ∥f 0∥ : norm_add_le _ _
... ≤ b 0 + ∥f 0∥ : begin
apply add_le_add_right,
simpa [dist_eq_norm] using b_bound n 0 0 (zero_le _) (zero_le _)
end },
exact le_of_tendsto (hF v).norm (eventually_of_forall A) },
-- Thus `F` is continuous, and we propose that as the limit point of our original Cauchy sequence.
let Fcont := Fmult.mk_continuous _ Fnorm,
use Fcont,
-- Our last task is to establish convergence to `F` in norm.
have : ∀ n, ∥f n - Fcont∥ ≤ b n,
{ assume n,
apply op_norm_le_bound _ (b0 n) (λ v, _),
have A : ∀ᶠ m in at_top, ∥(f n - f m) v∥ ≤ b n * ∏ i, ∥v i∥,
{ refine eventually_at_top.2 ⟨n, λ m hm, _⟩,
apply le_trans ((f n - f m).le_op_norm _) _,
exact mul_le_mul_of_nonneg_right (b_bound n m n (le_refl _) hm) (nonneg v) },
have B : tendsto (λ m, ∥(f n - f m) v∥) at_top (𝓝 (∥(f n - Fcont) v∥)) :=
tendsto.norm (tendsto_const_nhds.sub (hF v)),
exact le_of_tendsto B A },
erw tendsto_iff_norm_tendsto_zero,
exact squeeze_zero (λ n, norm_nonneg _) this b_lim,
end
end continuous_multilinear_map
/-- If a continuous multilinear map is constructed from a multilinear map via the constructor
`mk_continuous`, then its norm is bounded by the bound given to the constructor if it is
nonnegative. -/
lemma multilinear_map.mk_continuous_norm_le (f : multilinear_map 𝕜 E G) {C : ℝ} (hC : 0 ≤ C)
(H : ∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) : ∥f.mk_continuous C H∥ ≤ C :=
continuous_multilinear_map.op_norm_le_bound _ hC (λm, H m)
/-- If a continuous multilinear map is constructed from a multilinear map via the constructor
`mk_continuous`, then its norm is bounded by the bound given to the constructor if it is
nonnegative. -/
lemma multilinear_map.mk_continuous_norm_le' (f : multilinear_map 𝕜 E G) {C : ℝ}
(H : ∀ m, ∥f m∥ ≤ C * ∏ i, ∥m i∥) : ∥f.mk_continuous C H∥ ≤ max C 0 :=
continuous_multilinear_map.op_norm_le_bound _ (le_max_right _ _) $
λ m, (H m).trans $ mul_le_mul_of_nonneg_right (le_max_left _ _)
(prod_nonneg $ λ _ _, norm_nonneg _)
namespace continuous_multilinear_map
/-- Given a continuous multilinear map `f` on `n` variables (parameterized by `fin n`) and a subset
`s` of `k` of these variables, one gets a new continuous multilinear map on `fin k` by varying
these variables, and fixing the other ones equal to a given value `z`. It is denoted by
`f.restr s hk z`, where `hk` is a proof that the cardinality of `s` is `k`. The implicit
identification between `fin k` and `s` that we use is the canonical (increasing) bijection. -/
def restr {k n : ℕ} (f : (G [×n]→L[𝕜] G' : _))
(s : finset (fin n)) (hk : s.card = k) (z : G) : G [×k]→L[𝕜] G' :=
(f.to_multilinear_map.restr s hk z).mk_continuous
(∥f∥ * ∥z∥^(n-k)) $ λ v, multilinear_map.restr_norm_le _ _ _ _ f.le_op_norm _
lemma norm_restr {k n : ℕ} (f : G [×n]→L[𝕜] G') (s : finset (fin n)) (hk : s.card = k) (z : G) :
∥f.restr s hk z∥ ≤ ∥f∥ * ∥z∥ ^ (n - k) :=
begin
apply multilinear_map.mk_continuous_norm_le,
exact mul_nonneg (norm_nonneg _) (pow_nonneg (norm_nonneg _) _)
end
section
variables (𝕜 ι) (A : Type*) [normed_comm_ring A] [normed_algebra 𝕜 A]
/-- The continuous multilinear map on `A^ι`, where `A` is a normed commutative algebra
over `𝕜`, associating to `m` the product of all the `m i`.
See also `continuous_multilinear_map.mk_pi_algebra_fin`. -/
protected def mk_pi_algebra : continuous_multilinear_map 𝕜 (λ i : ι, A) A :=
multilinear_map.mk_continuous
(multilinear_map.mk_pi_algebra 𝕜 ι A) (if nonempty ι then 1 else ∥(1 : A)∥) $
begin
intro m,
casesI is_empty_or_nonempty ι with hι hι,
{ simp [eq_empty_of_is_empty univ, not_nonempty_iff.2 hι] },
{ simp [norm_prod_le' univ univ_nonempty, hι] }
end
variables {A 𝕜 ι}
@[simp] lemma mk_pi_algebra_apply (m : ι → A) :
continuous_multilinear_map.mk_pi_algebra 𝕜 ι A m = ∏ i, m i :=
rfl
lemma norm_mk_pi_algebra_le [nonempty ι] :
∥continuous_multilinear_map.mk_pi_algebra 𝕜 ι A∥ ≤ 1 :=
calc ∥continuous_multilinear_map.mk_pi_algebra 𝕜 ι A∥ ≤ if nonempty ι then 1 else ∥(1 : A)∥ :
multilinear_map.mk_continuous_norm_le _ (by split_ifs; simp [zero_le_one]) _
... = _ : if_pos ‹_›
lemma norm_mk_pi_algebra_of_empty [is_empty ι] :
∥continuous_multilinear_map.mk_pi_algebra 𝕜 ι A∥ = ∥(1 : A)∥ :=
begin
apply le_antisymm,
calc ∥continuous_multilinear_map.mk_pi_algebra 𝕜 ι A∥ ≤ if nonempty ι then 1 else ∥(1 : A)∥ :
multilinear_map.mk_continuous_norm_le _ (by split_ifs; simp [zero_le_one]) _
... = ∥(1 : A)∥ : if_neg (not_nonempty_iff.mpr ‹_›),
convert ratio_le_op_norm _ (λ _, (1 : A)),
simp [eq_empty_of_is_empty (univ : finset ι)],
end
@[simp] lemma norm_mk_pi_algebra [norm_one_class A] :
∥continuous_multilinear_map.mk_pi_algebra 𝕜 ι A∥ = 1 :=
begin
casesI is_empty_or_nonempty ι,
{ simp [norm_mk_pi_algebra_of_empty] },
{ refine le_antisymm norm_mk_pi_algebra_le _,
convert ratio_le_op_norm _ (λ _, 1); [skip, apply_instance],
simp },
end
end
section
variables (𝕜 n) (A : Type*) [normed_ring A] [normed_algebra 𝕜 A]
/-- The continuous multilinear map on `A^n`, where `A` is a normed algebra over `𝕜`, associating to
`m` the product of all the `m i`.
See also: `multilinear_map.mk_pi_algebra`. -/
protected def mk_pi_algebra_fin : continuous_multilinear_map 𝕜 (λ i : fin n, A) A :=
multilinear_map.mk_continuous
(multilinear_map.mk_pi_algebra_fin 𝕜 n A) (nat.cases_on n ∥(1 : A)∥ (λ _, 1)) $
begin
intro m,
cases n,
{ simp },
{ have : @list.of_fn A n.succ m ≠ [] := by simp,
simpa [← fin.prod_of_fn] using list.norm_prod_le' this }
end
variables {A 𝕜 n}
@[simp] lemma mk_pi_algebra_fin_apply (m : fin n → A) :
continuous_multilinear_map.mk_pi_algebra_fin 𝕜 n A m = (list.of_fn m).prod :=
rfl
lemma norm_mk_pi_algebra_fin_succ_le :
∥continuous_multilinear_map.mk_pi_algebra_fin 𝕜 n.succ A∥ ≤ 1 :=
multilinear_map.mk_continuous_norm_le _ zero_le_one _
lemma norm_mk_pi_algebra_fin_le_of_pos (hn : 0 < n) :
∥continuous_multilinear_map.mk_pi_algebra_fin 𝕜 n A∥ ≤ 1 :=
by cases n; [exact hn.false.elim, exact norm_mk_pi_algebra_fin_succ_le]
lemma norm_mk_pi_algebra_fin_zero :
∥continuous_multilinear_map.mk_pi_algebra_fin 𝕜 0 A∥ = ∥(1 : A)∥ :=
begin
refine le_antisymm (multilinear_map.mk_continuous_norm_le _ (norm_nonneg _) _) _,
convert ratio_le_op_norm _ (λ _, 1); [simp, apply_instance]
end
@[simp] lemma norm_mk_pi_algebra_fin [norm_one_class A] :
∥continuous_multilinear_map.mk_pi_algebra_fin 𝕜 n A∥ = 1 :=
begin
cases n,
{ simp [norm_mk_pi_algebra_fin_zero] },
{ refine le_antisymm norm_mk_pi_algebra_fin_succ_le _,
convert ratio_le_op_norm _ (λ _, 1); [skip, apply_instance],
simp }
end
end
variables (𝕜 ι)
/-- The canonical continuous multilinear map on `𝕜^ι`, associating to `m` the product of all the
`m i` (multiplied by a fixed reference element `z` in the target module) -/
protected def mk_pi_field (z : G) : continuous_multilinear_map 𝕜 (λ(i : ι), 𝕜) G :=
multilinear_map.mk_continuous
(multilinear_map.mk_pi_ring 𝕜 ι z) (∥z∥)
(λ m, by simp only [multilinear_map.mk_pi_ring_apply, norm_smul, normed_field.norm_prod,
mul_comm])
variables {𝕜 ι}
@[simp] lemma mk_pi_field_apply (z : G) (m : ι → 𝕜) :
(continuous_multilinear_map.mk_pi_field 𝕜 ι z : (ι → 𝕜) → G) m = (∏ i, m i) • z := rfl
lemma mk_pi_field_apply_one_eq_self (f : continuous_multilinear_map 𝕜 (λ(i : ι), 𝕜) G) :
continuous_multilinear_map.mk_pi_field 𝕜 ι (f (λi, 1)) = f :=
to_multilinear_map_inj f.to_multilinear_map.mk_pi_ring_apply_one_eq_self
variables (𝕜 ι G)
/-- Continuous multilinear maps on `𝕜^n` with values in `G` are in bijection with `G`, as such a
continuous multilinear map is completely determined by its value on the constant vector made of
ones. We register this bijection as a linear equivalence in
`continuous_multilinear_map.pi_field_equiv_aux`. The continuous linear equivalence is
`continuous_multilinear_map.pi_field_equiv`. -/
protected def pi_field_equiv_aux : G ≃ₗ[𝕜] (continuous_multilinear_map 𝕜 (λ(i : ι), 𝕜) G) :=
{ to_fun := λ z, continuous_multilinear_map.mk_pi_field 𝕜 ι z,
inv_fun := λ f, f (λi, 1),
map_add' := λ z z', by { ext m, simp [smul_add] },
map_smul' := λ c z, by { ext m, simp [smul_smul, mul_comm] },
left_inv := λ z, by simp,
right_inv := λ f, f.mk_pi_field_apply_one_eq_self }
/-- Continuous multilinear maps on `𝕜^n` with values in `G` are in bijection with `G`, as such a
continuous multilinear map is completely determined by its value on the constant vector made of
ones. We register this bijection as a continuous linear equivalence in
`continuous_multilinear_map.pi_field_equiv`. -/
protected def pi_field_equiv : G ≃L[𝕜] (continuous_multilinear_map 𝕜 (λ(i : ι), 𝕜) G) :=
{ continuous_to_fun := begin
refine (continuous_multilinear_map.pi_field_equiv_aux 𝕜 ι G).to_linear_map.continuous_of_bound
(1 : ℝ) (λz, _),
rw one_mul,
change ∥continuous_multilinear_map.mk_pi_field 𝕜 ι z∥ ≤ ∥z∥,
exact multilinear_map.mk_continuous_norm_le _ (norm_nonneg _) _
end,
continuous_inv_fun := begin
refine
(continuous_multilinear_map.pi_field_equiv_aux 𝕜 ι G).symm.to_linear_map.continuous_of_bound
(1 : ℝ) (λf, _),
rw one_mul,
change ∥f (λi, 1)∥ ≤ ∥f∥,
apply @continuous_multilinear_map.unit_le_op_norm 𝕜 ι (λ (i : ι), 𝕜) G _ _ _ _ _ _ _ f,
simp only [pi_norm_le_iff zero_le_one, norm_one],
exact λ _, le_rfl
end,
.. continuous_multilinear_map.pi_field_equiv_aux 𝕜 ι G }
end continuous_multilinear_map
namespace continuous_linear_map
lemma norm_comp_continuous_multilinear_map_le (g : G →L[𝕜] G')
(f : continuous_multilinear_map 𝕜 E G) :
∥g.comp_continuous_multilinear_map f∥ ≤ ∥g∥ * ∥f∥ :=
continuous_multilinear_map.op_norm_le_bound _ (mul_nonneg (norm_nonneg _) (norm_nonneg _)) $ λ m,
calc ∥g (f m)∥ ≤ ∥g∥ * (∥f∥ * ∏ i, ∥m i∥) : g.le_op_norm_of_le $ f.le_op_norm _
... = _ : (mul_assoc _ _ _).symm
/-- `continuous_linear_map.comp_continuous_multilinear_map` as a bundled continuous bilinear map. -/
def comp_continuous_multilinear_mapL :
(G →L[𝕜] G') →L[𝕜] continuous_multilinear_map 𝕜 E G →L[𝕜] continuous_multilinear_map 𝕜 E G' :=
linear_map.mk_continuous₂
(linear_map.mk₂ 𝕜 comp_continuous_multilinear_map (λ f₁ f₂ g, rfl) (λ c f g, rfl)
(λ f g₁ g₂, by { ext1, apply f.map_add }) (λ c f g, by { ext1, simp }))
1 $ λ f g, by { rw one_mul, exact f.norm_comp_continuous_multilinear_map_le g }
/-- Flip arguments in `f : G →L[𝕜] continuous_multilinear_map 𝕜 E G'` to get
`continuous_multilinear_map 𝕜 E (G →L[𝕜] G')` -/
def flip_multilinear (f : G →L[𝕜] continuous_multilinear_map 𝕜 E G') :
continuous_multilinear_map 𝕜 E (G →L[𝕜] G') :=
multilinear_map.mk_continuous
{ to_fun := λ m, linear_map.mk_continuous
{ to_fun := λ x, f x m,
map_add' := λ x y, by simp only [map_add, continuous_multilinear_map.add_apply],
map_smul' := λ c x, by simp only [continuous_multilinear_map.smul_apply, map_smul,
ring_hom.id_apply] }
(∥f∥ * ∏ i, ∥m i∥) $ λ x,
by { rw mul_right_comm, exact (f x).le_of_op_norm_le _ (f.le_op_norm x) },
map_add' := λ m i x y,
by { ext1, simp only [add_apply, continuous_multilinear_map.map_add, linear_map.coe_mk,
linear_map.mk_continuous_apply]},
map_smul' := λ m i c x,
by { ext1, simp only [coe_smul', continuous_multilinear_map.map_smul, linear_map.coe_mk,
linear_map.mk_continuous_apply, pi.smul_apply]} }
∥f∥ $ λ m,
linear_map.mk_continuous_norm_le _
(mul_nonneg (norm_nonneg f) (prod_nonneg $ λ i hi, norm_nonneg (m i))) _
end continuous_linear_map
open continuous_multilinear_map
namespace multilinear_map
/-- Given a map `f : G →ₗ[𝕜] multilinear_map 𝕜 E G'` and an estimate
`H : ∀ x m, ∥f x m∥ ≤ C * ∥x∥ * ∏ i, ∥m i∥`, construct a continuous linear
map from `G` to `continuous_multilinear_map 𝕜 E G'`.
In order to lift, e.g., a map `f : (multilinear_map 𝕜 E G) →ₗ[𝕜] multilinear_map 𝕜 E' G'`
to a map `(continuous_multilinear_map 𝕜 E G) →L[𝕜] continuous_multilinear_map 𝕜 E' G'`,
one can apply this construction to `f.comp continuous_multilinear_map.to_multilinear_map_linear`
which is a linear map from `continuous_multilinear_map 𝕜 E G` to `multilinear_map 𝕜 E' G'`. -/
def mk_continuous_linear (f : G →ₗ[𝕜] multilinear_map 𝕜 E G') (C : ℝ)
(H : ∀ x m, ∥f x m∥ ≤ C * ∥x∥ * ∏ i, ∥m i∥) :
G →L[𝕜] continuous_multilinear_map 𝕜 E G' :=
linear_map.mk_continuous
{ to_fun := λ x, (f x).mk_continuous (C * ∥x∥) $ H x,
map_add' := λ x y, by { ext1, simp },
map_smul' := λ c x, by { ext1, simp } }
(max C 0) $ λ x, ((f x).mk_continuous_norm_le' _).trans_eq $
by rw [max_mul_of_nonneg _ _ (norm_nonneg x), zero_mul]
lemma mk_continuous_linear_norm_le' (f : G →ₗ[𝕜] multilinear_map 𝕜 E G') (C : ℝ)
(H : ∀ x m, ∥f x m∥ ≤ C * ∥x∥ * ∏ i, ∥m i∥) :
∥mk_continuous_linear f C H∥ ≤ max C 0 :=
begin
dunfold mk_continuous_linear,
exact linear_map.mk_continuous_norm_le _ (le_max_right _ _) _
end
lemma mk_continuous_linear_norm_le (f : G →ₗ[𝕜] multilinear_map 𝕜 E G') {C : ℝ} (hC : 0 ≤ C)
(H : ∀ x m, ∥f x m∥ ≤ C * ∥x∥ * ∏ i, ∥m i∥) :
∥mk_continuous_linear f C H∥ ≤ C :=
(mk_continuous_linear_norm_le' f C H).trans_eq (max_eq_left hC)
/-- Given a map `f : multilinear_map 𝕜 E (multilinear_map 𝕜 E' G)` and an estimate
`H : ∀ m m', ∥f m m'∥ ≤ C * ∏ i, ∥m i∥ * ∏ i, ∥m' i∥`, upgrade all `multilinear_map`s in the type to
`continuous_multilinear_map`s. -/
def mk_continuous_multilinear (f : multilinear_map 𝕜 E (multilinear_map 𝕜 E' G)) (C : ℝ)
(H : ∀ m₁ m₂, ∥f m₁ m₂∥ ≤ C * (∏ i, ∥m₁ i∥) * ∏ i, ∥m₂ i∥) :
continuous_multilinear_map 𝕜 E (continuous_multilinear_map 𝕜 E' G) :=
mk_continuous
{ to_fun := λ m, mk_continuous (f m) (C * ∏ i, ∥m i∥) $ H m,
map_add' := λ m i x y, by { ext1, simp },
map_smul' := λ m i c x, by { ext1, simp } }
(max C 0) $ λ m, ((f m).mk_continuous_norm_le' _).trans_eq $
by { rw [max_mul_of_nonneg, zero_mul], exact prod_nonneg (λ _ _, norm_nonneg _) }
@[simp] lemma mk_continuous_multilinear_apply (f : multilinear_map 𝕜 E (multilinear_map 𝕜 E' G))
{C : ℝ} (H : ∀ m₁ m₂, ∥f m₁ m₂∥ ≤ C * (∏ i, ∥m₁ i∥) * ∏ i, ∥m₂ i∥) (m : Π i, E i) :
⇑(mk_continuous_multilinear f C H m) = f m :=
rfl
lemma mk_continuous_multilinear_norm_le' (f : multilinear_map 𝕜 E (multilinear_map 𝕜 E' G)) (C : ℝ)
(H : ∀ m₁ m₂, ∥f m₁ m₂∥ ≤ C * (∏ i, ∥m₁ i∥) * ∏ i, ∥m₂ i∥) :
∥mk_continuous_multilinear f C H∥ ≤ max C 0 :=
begin
dunfold mk_continuous_multilinear,
exact mk_continuous_norm_le _ (le_max_right _ _) _
end
lemma mk_continuous_multilinear_norm_le (f : multilinear_map 𝕜 E (multilinear_map 𝕜 E' G)) {C : ℝ}
(hC : 0 ≤ C) (H : ∀ m₁ m₂, ∥f m₁ m₂∥ ≤ C * (∏ i, ∥m₁ i∥) * ∏ i, ∥m₂ i∥) :
∥mk_continuous_multilinear f C H∥ ≤ C :=
(mk_continuous_multilinear_norm_le' f C H).trans_eq (max_eq_left hC)
end multilinear_map
namespace continuous_multilinear_map
lemma norm_comp_continuous_linear_le (g : continuous_multilinear_map 𝕜 E₁ G)
(f : Π i, E i →L[𝕜] E₁ i) :
∥g.comp_continuous_linear_map f∥ ≤ ∥g∥ * ∏ i, ∥f i∥ :=
op_norm_le_bound _ (mul_nonneg (norm_nonneg _) $ prod_nonneg $ λ i hi, norm_nonneg _) $ λ m,
calc ∥g (λ i, f i (m i))∥ ≤ ∥g∥ * ∏ i, ∥f i (m i)∥ : g.le_op_norm _
... ≤ ∥g∥ * ∏ i, (∥f i∥ * ∥m i∥) :
mul_le_mul_of_nonneg_left
(prod_le_prod (λ _ _, norm_nonneg _) (λ i hi, (f i).le_op_norm (m i))) (norm_nonneg g)
... = (∥g∥ * ∏ i, ∥f i∥) * ∏ i, ∥m i∥ : by rw [prod_mul_distrib, mul_assoc]
/-- `continuous_multilinear_map.comp_continuous_linear_map` as a bundled continuous linear map.
This implementation fixes `f : Π i, E i →L[𝕜] E₁ i`.
TODO: Actually, the map is multilinear in `f` but an attempt to formalize this failed because of
issues with class instances. -/
def comp_continuous_linear_mapL (f : Π i, E i →L[𝕜] E₁ i) :
continuous_multilinear_map 𝕜 E₁ G →L[𝕜] continuous_multilinear_map 𝕜 E G :=
linear_map.mk_continuous
{ to_fun := λ g, g.comp_continuous_linear_map f,
map_add' := λ g₁ g₂, rfl,
map_smul' := λ c g, rfl }
(∏ i, ∥f i∥) $ λ g, (norm_comp_continuous_linear_le _ _).trans_eq (mul_comm _ _)
@[simp] lemma comp_continuous_linear_mapL_apply (g : continuous_multilinear_map 𝕜 E₁ G)
(f : Π i, E i →L[𝕜] E₁ i) :
comp_continuous_linear_mapL f g = g.comp_continuous_linear_map f :=
rfl
lemma norm_comp_continuous_linear_mapL_le (f : Π i, E i →L[𝕜] E₁ i) :
∥@comp_continuous_linear_mapL 𝕜 ι E E₁ G _ _ _ _ _ _ _ _ _ f∥ ≤ (∏ i, ∥f i∥) :=
linear_map.mk_continuous_norm_le _ (prod_nonneg $ λ i _, norm_nonneg _) _
end continuous_multilinear_map
section currying
/-!
### Currying
We associate to a continuous multilinear map in `n+1` variables (i.e., based on `fin n.succ`) two
curried functions, named `f.curry_left` (which is a continuous linear map on `E 0` taking values
in continuous multilinear maps in `n` variables) and `f.curry_right` (which is a continuous
multilinear map in `n` variables taking values in continuous linear maps on `E (last n)`).
The inverse operations are called `uncurry_left` and `uncurry_right`.
We also register continuous linear equiv versions of these correspondences, in
`continuous_multilinear_curry_left_equiv` and `continuous_multilinear_curry_right_equiv`.
-/
open fin function
lemma continuous_linear_map.norm_map_tail_le
(f : Ei 0 →L[𝕜] (continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.succ) G)) (m : Πi, Ei i) :
∥f (m 0) (tail m)∥ ≤ ∥f∥ * ∏ i, ∥m i∥ :=
calc
∥f (m 0) (tail m)∥ ≤ ∥f (m 0)∥ * ∏ i, ∥(tail m) i∥ : (f (m 0)).le_op_norm _
... ≤ (∥f∥ * ∥m 0∥) * ∏ i, ∥(tail m) i∥ :
mul_le_mul_of_nonneg_right (f.le_op_norm _) (prod_nonneg (λi hi, norm_nonneg _))
... = ∥f∥ * (∥m 0∥ * ∏ i, ∥(tail m) i∥) : by ring
... = ∥f∥ * ∏ i, ∥m i∥ : by { rw prod_univ_succ, refl }
lemma continuous_multilinear_map.norm_map_init_le
(f : continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.cast_succ) (Ei (last n) →L[𝕜] G))
(m : Πi, Ei i) :
∥f (init m) (m (last n))∥ ≤ ∥f∥ * ∏ i, ∥m i∥ :=
calc
∥f (init m) (m (last n))∥ ≤ ∥f (init m)∥ * ∥m (last n)∥ : (f (init m)).le_op_norm _
... ≤ (∥f∥ * (∏ i, ∥(init m) i∥)) * ∥m (last n)∥ :
mul_le_mul_of_nonneg_right (f.le_op_norm _) (norm_nonneg _)
... = ∥f∥ * ((∏ i, ∥(init m) i∥) * ∥m (last n)∥) : mul_assoc _ _ _
... = ∥f∥ * ∏ i, ∥m i∥ : by { rw prod_univ_cast_succ, refl }
lemma continuous_multilinear_map.norm_map_cons_le
(f : continuous_multilinear_map 𝕜 Ei G) (x : Ei 0) (m : Π(i : fin n), Ei i.succ) :
∥f (cons x m)∥ ≤ ∥f∥ * ∥x∥ * ∏ i, ∥m i∥ :=
calc
∥f (cons x m)∥ ≤ ∥f∥ * ∏ i, ∥cons x m i∥ : f.le_op_norm _
... = (∥f∥ * ∥x∥) * ∏ i, ∥m i∥ : by { rw prod_univ_succ, simp [mul_assoc] }
lemma continuous_multilinear_map.norm_map_snoc_le
(f : continuous_multilinear_map 𝕜 Ei G) (m : Π(i : fin n), Ei i.cast_succ) (x : Ei (last n)) :
∥f (snoc m x)∥ ≤ ∥f∥ * (∏ i, ∥m i∥) * ∥x∥ :=
calc
∥f (snoc m x)∥ ≤ ∥f∥ * ∏ i, ∥snoc m x i∥ : f.le_op_norm _
... = ∥f∥ * (∏ i, ∥m i∥) * ∥x∥ : by { rw prod_univ_cast_succ, simp [mul_assoc] }
/-! #### Left currying -/
/-- Given a continuous linear map `f` from `E 0` to continuous multilinear maps on `n` variables,
construct the corresponding continuous multilinear map on `n+1` variables obtained by concatenating
the variables, given by `m ↦ f (m 0) (tail m)`-/
def continuous_linear_map.uncurry_left
(f : Ei 0 →L[𝕜] (continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.succ) G)) :
continuous_multilinear_map 𝕜 Ei G :=
(@linear_map.uncurry_left 𝕜 n Ei G _ _ _ _ _
(continuous_multilinear_map.to_multilinear_map_linear.comp f.to_linear_map)).mk_continuous
(∥f∥) (λm, continuous_linear_map.norm_map_tail_le f m)
@[simp] lemma continuous_linear_map.uncurry_left_apply
(f : Ei 0 →L[𝕜] (continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.succ) G)) (m : Πi, Ei i) :
f.uncurry_left m = f (m 0) (tail m) := rfl
/-- Given a continuous multilinear map `f` in `n+1` variables, split the first variable to obtain
a continuous linear map into continuous multilinear maps in `n` variables, given by
`x ↦ (m ↦ f (cons x m))`. -/
def continuous_multilinear_map.curry_left
(f : continuous_multilinear_map 𝕜 Ei G) :
Ei 0 →L[𝕜] (continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.succ) G) :=
linear_map.mk_continuous
{ -- define a linear map into `n` continuous multilinear maps from an `n+1` continuous multilinear
-- map
to_fun := λx, (f.to_multilinear_map.curry_left x).mk_continuous
(∥f∥ * ∥x∥) (f.norm_map_cons_le x),
map_add' := λx y, by { ext m, exact f.cons_add m x y },
map_smul' := λc x, by { ext m, exact f.cons_smul m c x } }
-- then register its continuity thanks to its boundedness properties.
(∥f∥) (λx, multilinear_map.mk_continuous_norm_le _ (mul_nonneg (norm_nonneg _) (norm_nonneg _)) _)
@[simp] lemma continuous_multilinear_map.curry_left_apply
(f : continuous_multilinear_map 𝕜 Ei G) (x : Ei 0) (m : Π(i : fin n), Ei i.succ) :
f.curry_left x m = f (cons x m) := rfl
@[simp] lemma continuous_linear_map.curry_uncurry_left
(f : Ei 0 →L[𝕜] (continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.succ) G)) :
f.uncurry_left.curry_left = f :=
begin
ext m x,
simp only [tail_cons, continuous_linear_map.uncurry_left_apply,
continuous_multilinear_map.curry_left_apply],
rw cons_zero
end
@[simp] lemma continuous_multilinear_map.uncurry_curry_left
(f : continuous_multilinear_map 𝕜 Ei G) : f.curry_left.uncurry_left = f :=
continuous_multilinear_map.to_multilinear_map_inj $ f.to_multilinear_map.uncurry_curry_left
variables (𝕜 Ei G)
/-- The space of continuous multilinear maps on `Π(i : fin (n+1)), E i` is canonically isomorphic to
the space of continuous linear maps from `E 0` to the space of continuous multilinear maps on
`Π(i : fin n), E i.succ `, by separating the first variable. We register this isomorphism in
`continuous_multilinear_curry_left_equiv 𝕜 E E₂`. The algebraic version (without topology) is given
in `multilinear_curry_left_equiv 𝕜 E E₂`.
The direct and inverse maps are given by `f.uncurry_left` and `f.curry_left`. Use these
unless you need the full framework of linear isometric equivs. -/
def continuous_multilinear_curry_left_equiv :
(Ei 0 →L[𝕜] (continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.succ) G)) ≃ₗᵢ[𝕜]
(continuous_multilinear_map 𝕜 Ei G) :=
linear_isometry_equiv.of_bounds
{ to_fun := continuous_linear_map.uncurry_left,
map_add' := λf₁ f₂, by { ext m, refl },
map_smul' := λc f, by { ext m, refl },
inv_fun := continuous_multilinear_map.curry_left,
left_inv := continuous_linear_map.curry_uncurry_left,
right_inv := continuous_multilinear_map.uncurry_curry_left }
(λ f, multilinear_map.mk_continuous_norm_le _ (norm_nonneg f) _)
(λ f, linear_map.mk_continuous_norm_le _ (norm_nonneg f) _)
variables {𝕜 Ei G}
@[simp] lemma continuous_multilinear_curry_left_equiv_apply
(f : Ei 0 →L[𝕜] (continuous_multilinear_map 𝕜 (λ i : fin n, Ei i.succ) G)) (v : Π i, Ei i) :
continuous_multilinear_curry_left_equiv 𝕜 Ei G f v = f (v 0) (tail v) := rfl
@[simp] lemma continuous_multilinear_curry_left_equiv_symm_apply
(f : continuous_multilinear_map 𝕜 Ei G) (x : Ei 0) (v : Π i : fin n, Ei i.succ) :
(continuous_multilinear_curry_left_equiv 𝕜 Ei G).symm f x v = f (cons x v) := rfl
@[simp] lemma continuous_multilinear_map.curry_left_norm
(f : continuous_multilinear_map 𝕜 Ei G) : ∥f.curry_left∥ = ∥f∥ :=
(continuous_multilinear_curry_left_equiv 𝕜 Ei G).symm.norm_map f
@[simp] lemma continuous_linear_map.uncurry_left_norm
(f : Ei 0 →L[𝕜] (continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.succ) G)) :
∥f.uncurry_left∥ = ∥f∥ :=
(continuous_multilinear_curry_left_equiv 𝕜 Ei G).norm_map f
/-! #### Right currying -/
/-- Given a continuous linear map `f` from continuous multilinear maps on `n` variables to
continuous linear maps on `E 0`, construct the corresponding continuous multilinear map on `n+1`
variables obtained by concatenating the variables, given by `m ↦ f (init m) (m (last n))`. -/
def continuous_multilinear_map.uncurry_right
(f : continuous_multilinear_map 𝕜 (λ i : fin n, Ei i.cast_succ) (Ei (last n) →L[𝕜] G)) :
continuous_multilinear_map 𝕜 Ei G :=
let f' : multilinear_map 𝕜 (λ(i : fin n), Ei i.cast_succ) (Ei (last n) →ₗ[𝕜] G) :=
{ to_fun := λ m, (f m).to_linear_map,
map_add' := λ m i x y, by simp,
map_smul' := λ m i c x, by simp } in
(@multilinear_map.uncurry_right 𝕜 n Ei G _ _ _ _ _ f').mk_continuous
(∥f∥) (λm, f.norm_map_init_le m)
@[simp] lemma continuous_multilinear_map.uncurry_right_apply
(f : continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.cast_succ) (Ei (last n) →L[𝕜] G))
(m : Πi, Ei i) :
f.uncurry_right m = f (init m) (m (last n)) := rfl
/-- Given a continuous multilinear map `f` in `n+1` variables, split the last variable to obtain
a continuous multilinear map in `n` variables into continuous linear maps, given by
`m ↦ (x ↦ f (snoc m x))`. -/
def continuous_multilinear_map.curry_right
(f : continuous_multilinear_map 𝕜 Ei G) :
continuous_multilinear_map 𝕜 (λ i : fin n, Ei i.cast_succ) (Ei (last n) →L[𝕜] G) :=
let f' : multilinear_map 𝕜 (λ(i : fin n), Ei i.cast_succ) (Ei (last n) →L[𝕜] G) :=
{ to_fun := λm, (f.to_multilinear_map.curry_right m).mk_continuous
(∥f∥ * ∏ i, ∥m i∥) $ λx, f.norm_map_snoc_le m x,
map_add' := λ m i x y, by { simp, refl },
map_smul' := λ m i c x, by { simp, refl } } in
f'.mk_continuous (∥f∥) (λm, linear_map.mk_continuous_norm_le _
(mul_nonneg (norm_nonneg _) (prod_nonneg (λj hj, norm_nonneg _))) _)
@[simp] lemma continuous_multilinear_map.curry_right_apply
(f : continuous_multilinear_map 𝕜 Ei G) (m : Π i : fin n, Ei i.cast_succ) (x : Ei (last n)) :
f.curry_right m x = f (snoc m x) := rfl
@[simp] lemma continuous_multilinear_map.curry_uncurry_right
(f : continuous_multilinear_map 𝕜 (λ i : fin n, Ei i.cast_succ) (Ei (last n) →L[𝕜] G)) :
f.uncurry_right.curry_right = f :=
begin
ext m x,
simp only [snoc_last, continuous_multilinear_map.curry_right_apply,
continuous_multilinear_map.uncurry_right_apply],
rw init_snoc
end
@[simp] lemma continuous_multilinear_map.uncurry_curry_right
(f : continuous_multilinear_map 𝕜 Ei G) : f.curry_right.uncurry_right = f :=
by { ext m, simp }
variables (𝕜 Ei G)
/--
The space of continuous multilinear maps on `Π(i : fin (n+1)), Ei i` is canonically isomorphic to
the space of continuous multilinear maps on `Π(i : fin n), Ei i.cast_succ` with values in the space
of continuous linear maps on `Ei (last n)`, by separating the last variable. We register this
isomorphism as a continuous linear equiv in `continuous_multilinear_curry_right_equiv 𝕜 Ei G`.
The algebraic version (without topology) is given in `multilinear_curry_right_equiv 𝕜 Ei G`.
The direct and inverse maps are given by `f.uncurry_right` and `f.curry_right`. Use these
unless you need the full framework of linear isometric equivs.
-/
def continuous_multilinear_curry_right_equiv :
(continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.cast_succ) (Ei (last n) →L[𝕜] G)) ≃ₗᵢ[𝕜]
(continuous_multilinear_map 𝕜 Ei G) :=
linear_isometry_equiv.of_bounds
{ to_fun := continuous_multilinear_map.uncurry_right,
map_add' := λf₁ f₂, by { ext m, refl },
map_smul' := λc f, by { ext m, refl },
inv_fun := continuous_multilinear_map.curry_right,
left_inv := continuous_multilinear_map.curry_uncurry_right,
right_inv := continuous_multilinear_map.uncurry_curry_right }
(λ f, multilinear_map.mk_continuous_norm_le _ (norm_nonneg f) _)
(λ f, multilinear_map.mk_continuous_norm_le _ (norm_nonneg f) _)
variables (n G')
/-- The space of continuous multilinear maps on `Π(i : fin (n+1)), G` is canonically isomorphic to
the space of continuous multilinear maps on `Π(i : fin n), G` with values in the space
of continuous linear maps on `G`, by separating the last variable. We register this
isomorphism as a continuous linear equiv in `continuous_multilinear_curry_right_equiv' 𝕜 n G G'`.
For a version allowing dependent types, see `continuous_multilinear_curry_right_equiv`. When there
are no dependent types, use the primed version as it helps Lean a lot for unification.
The direct and inverse maps are given by `f.uncurry_right` and `f.curry_right`. Use these
unless you need the full framework of linear isometric equivs. -/
def continuous_multilinear_curry_right_equiv' :
(G [×n]→L[𝕜] (G →L[𝕜] G')) ≃ₗᵢ[𝕜] (G [×n.succ]→L[𝕜] G') :=
continuous_multilinear_curry_right_equiv 𝕜 (λ (i : fin n.succ), G) G'
variables {n 𝕜 G Ei G'}
@[simp] lemma continuous_multilinear_curry_right_equiv_apply
(f : (continuous_multilinear_map 𝕜 (λ(i : fin n), Ei i.cast_succ) (Ei (last n) →L[𝕜] G)))
(v : Π i, Ei i) :
(continuous_multilinear_curry_right_equiv 𝕜 Ei G) f v = f (init v) (v (last n)) := rfl
@[simp] lemma continuous_multilinear_curry_right_equiv_symm_apply
(f : continuous_multilinear_map 𝕜 Ei G)
(v : Π (i : fin n), Ei i.cast_succ) (x : Ei (last n)) :
(continuous_multilinear_curry_right_equiv 𝕜 Ei G).symm f v x = f (snoc v x) := rfl
@[simp] lemma continuous_multilinear_curry_right_equiv_apply'
(f : G [×n]→L[𝕜] (G →L[𝕜] G')) (v : Π (i : fin n.succ), G) :
continuous_multilinear_curry_right_equiv' 𝕜 n G G' f v = f (init v) (v (last n)) := rfl
@[simp] lemma continuous_multilinear_curry_right_equiv_symm_apply'
(f : G [×n.succ]→L[𝕜] G') (v : Π (i : fin n), G) (x : G) :
(continuous_multilinear_curry_right_equiv' 𝕜 n G G').symm f v x = f (snoc v x) := rfl
@[simp] lemma continuous_multilinear_map.curry_right_norm
(f : continuous_multilinear_map 𝕜 Ei G) : ∥f.curry_right∥ = ∥f∥ :=
(continuous_multilinear_curry_right_equiv 𝕜 Ei G).symm.norm_map f
@[simp] lemma continuous_multilinear_map.uncurry_right_norm
(f : continuous_multilinear_map 𝕜 (λ i : fin n, Ei i.cast_succ) (Ei (last n) →L[𝕜] G)) :
∥f.uncurry_right∥ = ∥f∥ :=
(continuous_multilinear_curry_right_equiv 𝕜 Ei G).norm_map f
/-!
#### Currying with `0` variables
The space of multilinear maps with `0` variables is trivial: such a multilinear map is just an
arbitrary constant (note that multilinear maps in `0` variables need not map `0` to `0`!).
Therefore, the space of continuous multilinear maps on `(fin 0) → G` with values in `E₂` is
isomorphic (and even isometric) to `E₂`. As this is the zeroth step in the construction of iterated
derivatives, we register this isomorphism. -/
section
local attribute [instance] unique.subsingleton
variables {𝕜 G G'}
/-- Associating to a continuous multilinear map in `0` variables the unique value it takes. -/
def continuous_multilinear_map.uncurry0
(f : continuous_multilinear_map 𝕜 (λ (i : fin 0), G) G') : G' := f 0
variables (𝕜 G)
/-- Associating to an element `x` of a vector space `E₂` the continuous multilinear map in `0`
variables taking the (unique) value `x` -/
def continuous_multilinear_map.curry0 (x : G') : G [×0]→L[𝕜] G' :=
{ to_fun := λm, x,
map_add' := λ m i, fin.elim0 i,
map_smul' := λ m i, fin.elim0 i,
cont := continuous_const }
variable {G}
@[simp] lemma continuous_multilinear_map.curry0_apply (x : G') (m : (fin 0) → G) :
continuous_multilinear_map.curry0 𝕜 G x m = x := rfl
variable {𝕜}
@[simp] lemma continuous_multilinear_map.uncurry0_apply (f : G [×0]→L[𝕜] G') :
f.uncurry0 = f 0 := rfl
@[simp] lemma continuous_multilinear_map.apply_zero_curry0 (f : G [×0]→L[𝕜] G') {x : fin 0 → G} :
continuous_multilinear_map.curry0 𝕜 G (f x) = f :=
by { ext m, simp [(subsingleton.elim _ _ : x = m)] }
lemma continuous_multilinear_map.uncurry0_curry0 (f : G [×0]→L[𝕜] G') :
continuous_multilinear_map.curry0 𝕜 G (f.uncurry0) = f :=
by simp
variables (𝕜 G)
@[simp] lemma continuous_multilinear_map.curry0_uncurry0 (x : G') :
(continuous_multilinear_map.curry0 𝕜 G x).uncurry0 = x := rfl
@[simp] lemma continuous_multilinear_map.curry0_norm (x : G') :
∥continuous_multilinear_map.curry0 𝕜 G x∥ = ∥x∥ :=
begin
apply le_antisymm,
{ exact continuous_multilinear_map.op_norm_le_bound _ (norm_nonneg _) (λm, by simp) },
{ simpa using (continuous_multilinear_map.curry0 𝕜 G x).le_op_norm 0 }
end
variables {𝕜 G}
@[simp] lemma continuous_multilinear_map.fin0_apply_norm (f : G [×0]→L[𝕜] G') {x : fin 0 → G} :
∥f x∥ = ∥f∥ :=
begin
have : x = 0 := subsingleton.elim _ _, subst this,
refine le_antisymm (by simpa using f.le_op_norm 0) _,
have : ∥continuous_multilinear_map.curry0 𝕜 G (f.uncurry0)∥ ≤ ∥f.uncurry0∥ :=
continuous_multilinear_map.op_norm_le_bound _ (norm_nonneg _) (λm,
by simp [-continuous_multilinear_map.apply_zero_curry0]),
simpa
end
lemma continuous_multilinear_map.uncurry0_norm (f : G [×0]→L[𝕜] G') : ∥f.uncurry0∥ = ∥f∥ :=
by simp
variables (𝕜 G G')
/-- The continuous linear isomorphism between elements of a normed space, and continuous multilinear
maps in `0` variables with values in this normed space.
The direct and inverse maps are `uncurry0` and `curry0`. Use these unless you need the full
framework of linear isometric equivs. -/
def continuous_multilinear_curry_fin0 : (G [×0]→L[𝕜] G') ≃ₗᵢ[𝕜] G' :=
{ to_fun := λf, continuous_multilinear_map.uncurry0 f,
inv_fun := λf, continuous_multilinear_map.curry0 𝕜 G f,
map_add' := λf g, rfl,
map_smul' := λc f, rfl,
left_inv := continuous_multilinear_map.uncurry0_curry0,
right_inv := continuous_multilinear_map.curry0_uncurry0 𝕜 G,
norm_map' := continuous_multilinear_map.uncurry0_norm }
variables {𝕜 G G'}
@[simp] lemma continuous_multilinear_curry_fin0_apply (f : G [×0]→L[𝕜] G') :
continuous_multilinear_curry_fin0 𝕜 G G' f = f 0 := rfl
@[simp] lemma continuous_multilinear_curry_fin0_symm_apply (x : G') (v : (fin 0) → G) :
(continuous_multilinear_curry_fin0 𝕜 G G').symm x v = x := rfl
end
/-! #### With 1 variable -/
variables (𝕜 G G')
/-- Continuous multilinear maps from `G^1` to `G'` are isomorphic with continuous linear maps from
`G` to `G'`. -/
def continuous_multilinear_curry_fin1 : (G [×1]→L[𝕜] G') ≃ₗᵢ[𝕜] (G →L[𝕜] G') :=
(continuous_multilinear_curry_right_equiv 𝕜 (λ (i : fin 1), G) G').symm.trans
(continuous_multilinear_curry_fin0 𝕜 G (G →L[𝕜] G'))
variables {𝕜 G G'}
@[simp] lemma continuous_multilinear_curry_fin1_apply (f : G [×1]→L[𝕜] G') (x : G) :
continuous_multilinear_curry_fin1 𝕜 G G' f x = f (fin.snoc 0 x) := rfl
@[simp] lemma continuous_multilinear_curry_fin1_symm_apply
(f : G →L[𝕜] G') (v : (fin 1) → G) :
(continuous_multilinear_curry_fin1 𝕜 G G').symm f v = f (v 0) := rfl
namespace continuous_multilinear_map
variables (𝕜 G G')
/-- An equivalence of the index set defines a linear isometric equivalence between the spaces
of multilinear maps. -/
def dom_dom_congr (σ : ι ≃ ι') :
continuous_multilinear_map 𝕜 (λ _ : ι, G) G' ≃ₗᵢ[𝕜]
continuous_multilinear_map 𝕜 (λ _ : ι', G) G' :=
linear_isometry_equiv.of_bounds
{ to_fun := λ f, (multilinear_map.dom_dom_congr σ f.to_multilinear_map).mk_continuous ∥f∥ $
λ m, (f.le_op_norm (λ i, m (σ i))).trans_eq $ by rw [← σ.prod_comp],
inv_fun := λ f, (multilinear_map.dom_dom_congr σ.symm f.to_multilinear_map).mk_continuous ∥f∥ $
λ m, (f.le_op_norm (λ i, m (σ.symm i))).trans_eq $ by rw [← σ.symm.prod_comp],
left_inv := λ f, ext $ λ m, congr_arg f $ by simp only [σ.symm_apply_apply],
right_inv := λ f, ext $ λ m, congr_arg f $ by simp only [σ.apply_symm_apply],
map_add' := λ f g, rfl,
map_smul' := λ c f, rfl }
(λ f, multilinear_map.mk_continuous_norm_le _ (norm_nonneg f) _)
(λ f, multilinear_map.mk_continuous_norm_le _ (norm_nonneg f) _)
variables {𝕜 G G'}
section
variable [decidable_eq (ι ⊕ ι')]
/-- A continuous multilinear map with variables indexed by `ι ⊕ ι'` defines a continuous multilinear
map with variables indexed by `ι` taking values in the space of continuous multilinear maps with
variables indexed by `ι'`. -/
def curry_sum (f : continuous_multilinear_map 𝕜 (λ x : ι ⊕ ι', G) G') :
continuous_multilinear_map 𝕜 (λ x : ι, G) (continuous_multilinear_map 𝕜 (λ x : ι', G) G') :=
multilinear_map.mk_continuous_multilinear (multilinear_map.curry_sum f.to_multilinear_map) (∥f∥) $
λ m m', by simpa [fintype.prod_sum_type, mul_assoc] using f.le_op_norm (sum.elim m m')
@[simp] lemma curry_sum_apply (f : continuous_multilinear_map 𝕜 (λ x : ι ⊕ ι', G) G')
(m : ι → G) (m' : ι' → G) :
f.curry_sum m m' = f (sum.elim m m') :=
rfl
/-- A continuous multilinear map with variables indexed by `ι` taking values in the space of
continuous multilinear maps with variables indexed by `ι'` defines a continuous multilinear map with
variables indexed by `ι ⊕ ι'`. -/
def uncurry_sum
(f : continuous_multilinear_map 𝕜 (λ x : ι, G) (continuous_multilinear_map 𝕜 (λ x : ι', G) G')) :
continuous_multilinear_map 𝕜 (λ x : ι ⊕ ι', G) G' :=
multilinear_map.mk_continuous
(to_multilinear_map_linear.comp_multilinear_map f.to_multilinear_map).uncurry_sum (∥f∥) $ λ m,
by simpa [fintype.prod_sum_type, mul_assoc]
using (f (m ∘ sum.inl)).le_of_op_norm_le (m ∘ sum.inr) (f.le_op_norm _)
@[simp] lemma uncurry_sum_apply
(f : continuous_multilinear_map 𝕜 (λ x : ι, G) (continuous_multilinear_map 𝕜 (λ x : ι', G) G'))
(m : ι ⊕ ι' → G) :
f.uncurry_sum m = f (m ∘ sum.inl) (m ∘ sum.inr) :=
rfl
variables (𝕜 ι ι' G G')
/-- Linear isometric equivalence between the space of continuous multilinear maps with variables
indexed by `ι ⊕ ι'` and the space of continuous multilinear maps with variables indexed by `ι`
taking values in the space of continuous multilinear maps with variables indexed by `ι'`.
The forward and inverse functions are `continuous_multilinear_map.curry_sum`
and `continuous_multilinear_map.uncurry_sum`. Use this definition only if you need
some properties of `linear_isometry_equiv`. -/
def curry_sum_equiv : continuous_multilinear_map 𝕜 (λ x : ι ⊕ ι', G) G' ≃ₗᵢ[𝕜]
continuous_multilinear_map 𝕜 (λ x : ι, G) (continuous_multilinear_map 𝕜 (λ x : ι', G) G') :=
linear_isometry_equiv.of_bounds
{ to_fun := curry_sum,
inv_fun := uncurry_sum,
map_add' := λ f g, by { ext, refl },
map_smul' := λ c f, by { ext, refl },
left_inv := λ f, by { ext m, exact congr_arg f (sum.elim_comp_inl_inr m) },
right_inv := λ f, by { ext m₁ m₂, change f _ _ = f _ _,
rw [sum.elim_comp_inl, sum.elim_comp_inr] } }
(λ f, multilinear_map.mk_continuous_multilinear_norm_le _ (norm_nonneg f) _)
(λ f, multilinear_map.mk_continuous_norm_le _ (norm_nonneg f) _)
end
section
variables (𝕜 G G') {k l : ℕ} {s : finset (fin n)}
/-- If `s : finset (fin n)` is a finite set of cardinality `k` and its complement has cardinality
`l`, then the space of continuous multilinear maps `G [×n]→L[𝕜] G'` of `n` variables is isomorphic
to the space of continuous multilinear maps `G [×k]→L[𝕜] G [×l]→L[𝕜] G'` of `k` variables taking
values in the space of continuous multilinear maps of `l` variables. -/
def curry_fin_finset {k l n : ℕ} {s : finset (fin n)}
(hk : s.card = k) (hl : sᶜ.card = l) :
(G [×n]→L[𝕜] G') ≃ₗᵢ[𝕜] (G [×k]→L[𝕜] G [×l]→L[𝕜] G') :=
(dom_dom_congr 𝕜 G G' (fin_sum_equiv_of_finset hk hl).symm).trans
(curry_sum_equiv 𝕜 (fin k) (fin l) G G')
variables {𝕜 G G'}
@[simp] lemma curry_fin_finset_apply (hk : s.card = k) (hl : sᶜ.card = l)
(f : G [×n]→L[𝕜] G') (mk : fin k → G) (ml : fin l → G) :
curry_fin_finset 𝕜 G G' hk hl f mk ml =
f (λ i, sum.elim mk ml ((fin_sum_equiv_of_finset hk hl).symm i)) :=
rfl
@[simp] lemma curry_fin_finset_symm_apply (hk : s.card = k) (hl : sᶜ.card = l)
(f : G [×k]→L[𝕜] G [×l]→L[𝕜] G') (m : fin n → G) :
(curry_fin_finset 𝕜 G G' hk hl).symm f m =
f (λ i, m $ fin_sum_equiv_of_finset hk hl (sum.inl i))
(λ i, m $ fin_sum_equiv_of_finset hk hl (sum.inr i)) :=
rfl
@[simp] lemma curry_fin_finset_symm_apply_piecewise_const (hk : s.card = k) (hl : sᶜ.card = l)
(f : G [×k]→L[𝕜] G [×l]→L[𝕜] G') (x y : G) :
(curry_fin_finset 𝕜 G G' hk hl).symm f (s.piecewise (λ _, x) (λ _, y)) = f (λ _, x) (λ _, y) :=
multilinear_map.curry_fin_finset_symm_apply_piecewise_const hk hl _ x y
@[simp] lemma curry_fin_finset_symm_apply_const (hk : s.card = k) (hl : sᶜ.card = l)
(f : G [×k]→L[𝕜] G [×l]→L[𝕜] G') (x : G) :
(curry_fin_finset 𝕜 G G' hk hl).symm f (λ _, x) = f (λ _, x) (λ _, x) :=
rfl
@[simp] lemma curry_fin_finset_apply_const (hk : s.card = k) (hl : sᶜ.card = l)
(f : G [×n]→L[𝕜] G') (x y : G) :
curry_fin_finset 𝕜 G G' hk hl f (λ _, x) (λ _, y) = f (s.piecewise (λ _, x) (λ _, y)) :=
begin
refine (curry_fin_finset_symm_apply_piecewise_const hk hl _ _ _).symm.trans _, -- `rw` fails
rw linear_isometry_equiv.symm_apply_apply
end
end
end continuous_multilinear_map
end currying
|
83f1f696053bded8ae065bacbf2195b5faa7be2d | 853df553b1d6ca524e3f0a79aedd32dde5d27ec3 | /src/tactic/interactive_expr.lean | 5f97ea18bc8839dbea7f987b4772b334e06013ae | [
"Apache-2.0"
] | permissive | DanielFabian/mathlib | efc3a50b5dde303c59eeb6353ef4c35a345d7112 | f520d07eba0c852e96fe26da71d85bf6d40fcc2a | refs/heads/master | 1,668,739,922,971 | 1,595,201,756,000 | 1,595,201,756,000 | 279,469,476 | 0 | 0 | null | 1,594,696,604,000 | 1,594,696,604,000 | null | UTF-8 | Lean | false | false | 12,805 | lean | /-
Copyright (c) 2020 E.W.Ayers. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: E.W.Ayers
-/
/-!
# Widgets used for tactic state and term-mode goal display
The vscode extension supports the display of interactive widgets.
Default implementation of these widgets are included in the core
library. We override them here using `vm_override` so that we can
change them quickly without waiting for the next Lean release.
The function `widget_override.interactive_expression.mk` renders a single
expression as a widget component. Each goal in a tactic state is rendered
using the `widget_override.tactic_view_goal` function,
a complete tactic state is rendered using
`widget_override.tactic_view_component`.
Lean itself calls the `widget_override.term_goal_widget` function to render
term-mode goals and `widget_override.tactic_state_widget` to render the
tactic state in a tactic proof.
-/
namespace widget_override
open widget
open tagged_format
open widget.html widget.attr
namespace interactive_expression
/-- eformat but without any of the formatting stuff like highlighting, groups etc. -/
meta inductive sf : Type
| tag_expr : expr.address → expr → sf → sf
| compose : sf → sf → sf
| of_string : string → sf
/-- Prints a debugging representation of an `sf` object. -/
meta def sf.repr : sf → format
| (sf.tag_expr addr e a) := format.group $ format.nest 2 $
"(tag_expr " ++ to_fmt addr ++ format.line ++
"`(" ++ to_fmt e ++ ")" ++ format.line ++ a.repr ++ ")"
| (sf.compose a b) := a.repr ++ format.line ++ b.repr
| (sf.of_string s) := repr s
meta instance : has_to_format sf := ⟨sf.repr⟩
meta instance : has_to_string sf := ⟨λ s, s.repr.to_string⟩
meta instance : has_repr sf := ⟨λ s, s.repr.to_string⟩
/-- Constructs an `sf` from an `eformat` by forgetting grouping, nesting, etc. -/
meta def sf.of_eformat : eformat → sf
| (tag ⟨ea,e⟩ m) := sf.tag_expr ea e $ sf.of_eformat m
| (group m) := sf.of_eformat m
| (nest i m) := sf.of_eformat m
| (highlight i m) := sf.of_eformat m
| (of_format f) := sf.of_string $ format.to_string f
| (compose x y) := sf.compose (sf.of_eformat x) (sf.of_eformat y)
/-- Flattens an `sf`, i.e. merges adjacent `of_string` constructors. -/
meta def sf.flatten : sf → sf
| (sf.tag_expr e ea m) := (sf.tag_expr e ea $ sf.flatten m)
| (sf.compose x y) :=
match (sf.flatten x), (sf.flatten y) with
| (sf.of_string sx), (sf.of_string sy) := sf.of_string (sx ++ sy)
| (sf.of_string sx), (sf.compose (sf.of_string sy) z) := sf.compose (sf.of_string (sx ++ sy)) z
| (sf.compose x (sf.of_string sy)), (sf.of_string sz) := sf.compose x (sf.of_string (sy ++ sz))
| (sf.compose x (sf.of_string sy1)), (sf.compose (sf.of_string sy2) z) := sf.compose x (sf.compose (sf.of_string (sy1 ++ sy2)) z)
| x, y := sf.compose x y
end
| (sf.of_string s) := sf.of_string s
/--
The actions accepted by an expression widget.
-/
meta inductive action (γ : Type)
| on_mouse_enter : subexpr → action
| on_mouse_leave_all : action
| on_click : subexpr → action
| on_tooltip_action : γ → action
| on_close_tooltip : action
/--
Renders a subexpression as a list of html elements.
-/
meta def view {γ} (tooltip_component : tc subexpr (action γ)) (click_address : option expr.address) (select_address : option expr.address) :
subexpr → sf → tactic (list (html (action γ)))
| ⟨ce, current_address⟩ (sf.tag_expr ea e m) := do
let new_address := current_address ++ ea,
let select_attrs : list (attr (action γ)) := if some new_address = select_address then [className "highlight"] else [],
click_attrs : list (attr (action γ)) ←
if some new_address = click_address then do
content ← tc.to_html tooltip_component (e, new_address),
pure [tooltip $ h "div" [] [
h "button" [cn "fr pointer ba br3", on_click (λ _, action.on_close_tooltip)] ["x"],
content
]]
else pure [],
let as := [className "expr-boundary", key (ea)] ++ select_attrs ++ click_attrs,
inner ← view (e,new_address) m,
pure [h "span" as inner]
| ca (sf.compose x y) := pure (++) <*> view ca x <*> view ca y
| ca (sf.of_string s) := pure
[h "span" [
on_mouse_enter (λ _, action.on_mouse_enter ca),
on_click (λ _, action.on_click ca),
key s
] [html.of_string s]]
/-- Make an interactive expression. -/
meta def mk {γ} (tooltip : tc subexpr γ) : tc expr γ :=
let tooltip_comp :=
component.with_should_update (λ (x y : tactic_state × expr × expr.address), x.2.2 ≠ y.2.2)
$ component.map_action (action.on_tooltip_action) tooltip in
tc.mk_simple
(action γ)
(option subexpr × option subexpr)
(λ e, pure $ (none, none))
(λ e ⟨ca, sa⟩ act, pure $
match act with
| (action.on_mouse_enter ⟨e, ea⟩) := ((ca, some (e, ea)), none)
| (action.on_mouse_leave_all) := ((ca, none), none)
| (action.on_click ⟨e, ea⟩) := if some (e,ea) = ca then ((none, sa), none) else ((some (e, ea), sa), none)
| (action.on_tooltip_action g) := ((none, sa), some g)
| (action.on_close_tooltip) := ((none, sa), none)
end
)
(λ e ⟨ca, sa⟩, do
ts ← tactic.read,
let m : sf := sf.flatten $ sf.of_eformat $ tactic_state.pp_tagged ts e,
let m : sf := sf.tag_expr [] e m, -- [hack] in pp.cpp I forgot to add an expr-boundary for the root expression.
v ← view tooltip_comp (prod.snd <$> ca) (prod.snd <$> sa) ⟨e, []⟩ m,
pure $
[ h "span" [
className "expr",
key e.hash,
on_mouse_leave (λ _, action.on_mouse_leave_all) ] $ v
]
)
/-- Render the implicit arguments for an expression in fancy, little pills. -/
meta def implicit_arg_list (tooltip : tc subexpr empty) (e : expr) : tactic $ html empty := do
fn ← (mk tooltip) $ expr.get_app_fn e,
args ← list.mmap (mk tooltip) $ expr.get_app_args e,
pure $ h "div" []
( (h "span" [className "bg-blue br3 ma1 ph2 white"] [fn]) ::
list.map (λ a, h "span" [className "bg-gray br3 ma1 ph2 white"] [a]) args
)
/--
Component for the type tooltip.
-/
meta def type_tooltip : tc subexpr empty :=
tc.stateless (λ ⟨e,ea⟩, do
y ← tactic.infer_type e,
y_comp ← mk type_tooltip y,
implicit_args ← implicit_arg_list type_tooltip e,
pure [
h "div" [] [
h "div" [] [y_comp],
h "hr" [] [],
implicit_args
]
]
)
end interactive_expression
/--
Supported tactic state filters.
-/
@[derive decidable_eq]
meta inductive filter_type
| none
| no_instances
| only_props
/--
Filters a local constant using the given filter.
-/
meta def filter_local : filter_type → expr → tactic bool
| (filter_type.none) e := pure tt
| (filter_type.no_instances) e := do
t ← tactic.infer_type e,
bnot <$> tactic.is_class t
| (filter_type.only_props) e := do
t ← tactic.infer_type e,
tactic.is_prop t
/--
Component for the filter dropdown.
-/
meta def filter_component : component filter_type filter_type :=
component.stateless (λ lf,
[ h "label" [] ["filter: "],
select [
⟨filter_type.none, "0", ["no filter"]⟩,
⟨filter_type.no_instances, "1", ["no instances"]⟩,
⟨filter_type.only_props, "2", ["only props"]⟩
] lf
]
)
/--
Converts a name into an html element.
-/
meta def html.of_name {α : Type} : name → html α
| n := html.of_string $ name.to_string n
open tactic
/--
Component that shows a type.
-/
meta def show_type_component : tc expr empty :=
tc.stateless (λ x, do
y ← infer_type x,
y_comp ← interactive_expression.mk interactive_expression.type_tooltip $ y,
pure y_comp
)
/-- A group of local constants in the context that should be rendered as one line. -/
@[derive decidable_eq]
meta structure local_collection :=
(key : string)
(locals : list expr)
(type : expr)
(value : option expr)
/-- Converts a single local constant into a (singleton) `local_collection` -/
meta def to_local_collection (l : expr) : tactic local_collection :=
tactic.unsafe.type_context.run $ do
lctx ← tactic.unsafe.type_context.get_local_context,
some ldecl ← pure $ lctx.get_local_decl l.local_uniq_name,
pure {
key := l.local_uniq_name.repr,
locals := [l],
type := ldecl.type,
value := ldecl.value }
/-- Groups consecutive local collections by type -/
meta def group_local_collection : list local_collection → list local_collection
| (a :: b :: rest) :=
if a.type = b.type ∧ a.value = b.value then
group_local_collection $
{ locals := a.locals ++ b.locals, ..a } :: rest
else
a :: group_local_collection (b :: rest)
| ls := ls
/-- Component that displays the main (first) goal. -/
meta def tactic_view_goal {γ} (local_c : tc local_collection γ) (target_c : tc expr γ) : tc filter_type γ :=
tc.stateless $ λ ft, do
g@(expr.mvar u_n pp_n y) ← main_goal,
t ← get_tag g,
let case_tag : list (html γ) :=
match interactive.case_tag.parse t with
| some t :=
[h "li" [key "_case"] $ [h "span" [cn "goal-case b"] ["case"]] ++
(t.case_names.bind $ λ n, [" ", n])]
| none := []
end,
lcs ← local_context,
lcs ← list.mfilter (filter_local ft) lcs,
lcs ← lcs.mmap $ to_local_collection,
let lcs := group_local_collection lcs,
lchs ← lcs.mmap (λ lc, do
lh ← local_c lc,
let ns : list (html γ) := lc.locals.map $ λ n,
h "span" [cn "goal-hyp b pr2", key n.local_uniq_name] [html.of_name n.local_pp_name],
pure $ h "li" [key lc.key] (ns ++ [": ", h "span" [cn "goal-hyp-type", key "type"] [lh]])),
t_comp ← target_c g,
pure $ h "ul" [key g.hash, className "list pl0 font-code"] $ case_tag ++ lchs ++ [
h "li" [key u_n] [
h "span" [cn "goal-vdash b"] ["⊢ "],
t_comp
]]
/--
Actions accepted by the `tactic_view_component`.
-/
meta inductive tactic_view_action (γ : Type)
| out (a:γ): tactic_view_action
| filter (f: filter_type): tactic_view_action
/-- Component that displays all goals, together with the `$n goals` message. -/
meta def tactic_view_component {γ} (local_c : tc local_collection γ) (target_c : tc expr γ) : tc unit γ :=
tc.mk_simple
(tactic_view_action γ)
(filter_type)
(λ _, pure $ filter_type.none)
(λ ⟨⟩ ft a, match a with
| (tactic_view_action.out a) := pure (ft, some a)
| (tactic_view_action.filter ft) := pure (ft, none)
end)
(λ ⟨⟩ ft, do
gs ← get_goals,
hs ← gs.mmap (λ g, do set_goals [g], flip tc.to_html ft $ tactic_view_goal local_c target_c),
set_goals gs,
let goal_message : html γ :=
if gs.length = 0 then
h "div" [cn "f5"] ["goals accomplished 🎉"]
else if gs.length = 1 then
"1 goal"
else
html.of_string $ to_string gs.length ++ " goals",
let goal_message : html γ := h "strong" [cn "goal-goals"] [goal_message],
let goals : html γ := h "ul" [className "list pl0"]
$ list.map_with_index (λ i x,
h "li" [className $ "lh-copy mt2", key i] [x])
$ (goal_message :: hs),
pure [
h "div" [className "fr"] [html.of_component ft $ component.map_action tactic_view_action.filter filter_component],
html.map_action tactic_view_action.out goals
])
/-- Component that displays the term-mode goal. -/
meta def tactic_view_term_goal {γ} (local_c : tc local_collection γ) (target_c : tc expr γ) : tc unit γ :=
tc.stateless $ λ _, do
goal ← flip tc.to_html (filter_type.none) $ tactic_view_goal local_c target_c,
pure [h "ul" [className "list pl0"] [
h "li" [className "lh-copy"] [h "strong" [cn "goal-goals"] ["expected type:"]],
h "li" [className "lh-copy"] [goal]]]
/--
Component showing a local collection.
-/
meta def show_local_collection_component : tc local_collection empty :=
tc.stateless (λ lc, do
(l::_) ← pure lc.locals,
c ← show_type_component l,
match lc.value with
| some v := do
v ← interactive_expression.mk interactive_expression.type_tooltip v,
pure [c, " := ", v]
| none := pure [c]
end)
/--
Renders the current tactic state.
-/
meta def tactic_render : tc unit empty :=
component.ignore_action $ tactic_view_component show_local_collection_component show_type_component
/--
Component showing the current tactic state.
-/
meta def tactic_state_widget : component tactic_state empty :=
tc.to_component tactic_render
/--
Widget used to display term-proof goals.
-/
meta def term_goal_widget : component tactic_state empty :=
(tactic_view_term_goal show_local_collection_component show_type_component).to_component
end widget_override
attribute [vm_override widget_override.term_goal_widget] widget.term_goal_widget
attribute [vm_override widget_override.tactic_state_widget] widget.tactic_state_widget
|
972e01ad8bc28cb8b432fd4722c80c77ac629fdb | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /tests/lean/diamond8.lean | 790fbfe3edd6695fecaf73c2c0176e05f4b25d0b | [
"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 | 720 | lean | class One (M : Type u) where one : M
instance {M} [One M] : OfNat M (nat_lit 1) := ⟨One.one⟩
class Zero (A : Type u) where zero : A
instance {A} [Zero A] : OfNat A (nat_lit 0) := ⟨Zero.zero⟩
class Monoid (M : Type u) extends Mul M, One M where
mul_one (m : M) : m * 1 = m
class AddCommMonoid (A : Type u) extends Add A, Zero A
class MonoidWithZero (M₀ : Type u) extends Monoid M₀, Zero M₀
class Semiring (R : Type u) extends AddCommMonoid R, MonoidWithZero R, One R
#print Semiring -- only toMonoid field, no duplicate toOne
def oneViaMonoid {M} [Monoid M] : M := 1
example {R} [Semiring R] : (1 : R) = oneViaMonoid := rfl
example : Semiring Nat where
mul_one := by simp
zero := 0
one := 1
|
9cf8d83aef6589371aa3c7c4db3ccc9bc6c0f181 | 57c233acf9386e610d99ed20ef139c5f97504ba3 | /src/order/filter/basic.lean | cc91d9f50492ef08a4ee558bca51c677676d3be7 | [
"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 | 117,677 | 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
-/
import control.traversable.instances
import data.set.finite
import order.copy
import tactic.monotonicity
/-!
# Theory of filters on sets
## Main definitions
* `filter` : filters on a set;
* `at_top`, `at_bot`, `cofinite`, `principal` : specific filters;
* `map`, `comap`, `prod` : operations on filters;
* `tendsto` : limit with respect to filters;
* `eventually` : `f.eventually p` means `{x | p x} ∈ f`;
* `frequently` : `f.frequently p` means `{x | ¬p x} ∉ f`;
* `filter_upwards [h₁, ..., hₙ]` : takes a list of proofs `hᵢ : sᵢ ∈ f`, and replaces a goal `s ∈ f`
with `∀ x, x ∈ s₁ → ... → x ∈ sₙ → x ∈ s`;
* `ne_bot f` : an utility class stating that `f` is a non-trivial filter.
Filters on a type `X` are sets of sets of `X` satisfying three conditions. They are mostly used to
abstract two related kinds of ideas:
* *limits*, including finite or infinite limits of sequences, finite or infinite limits of functions
at a point or at infinity, etc...
* *things happening eventually*, including things happening for large enough `n : ℕ`, or near enough
a point `x`, or for close enough pairs of points, or things happening almost everywhere in the
sense of measure theory. Dually, filters can also express the idea of *things happening often*:
for arbitrarily large `n`, or at a point in any neighborhood of given a point etc...
In this file, we define the type `filter X` of filters on `X`, and endow it with a complete lattice
structure. This structure is lifted from the lattice structure on `set (set X)` using the Galois
insertion which maps a filter to its elements in one direction, and an arbitrary set of sets to
the smallest filter containing it in the other direction.
We also prove `filter` is a monadic functor, with a push-forward operation
`filter.map` and a pull-back operation `filter.comap` that form a Galois connections for the
order on filters.
Finally we describe a product operation `filter X → filter Y → filter (X × Y)`.
The examples of filters appearing in the description of the two motivating ideas are:
* `(at_top : filter ℕ)` : made of sets of `ℕ` containing `{n | n ≥ N}` for some `N`
* `𝓝 x` : made of neighborhoods of `x` in a topological space (defined in topology.basic)
* `𝓤 X` : made of entourages of a uniform space (those space are generalizations of metric spaces
defined in topology.uniform_space.basic)
* `μ.ae` : made of sets whose complement has zero measure with respect to `μ` (defined in
`measure_theory.measure_space`)
The general notion of limit of a map with respect to filters on the source and target types
is `filter.tendsto`. It is defined in terms of the order and the push-forward operation.
The predicate "happening eventually" is `filter.eventually`, and "happening often" is
`filter.frequently`, whose definitions are immediate after `filter` is defined (but they come
rather late in this file in order to immediately relate them to the lattice structure).
For instance, anticipating on topology.basic, the statement: "if a sequence `u` converges to
some `x` and `u n` belongs to a set `M` for `n` large enough then `x` is in the closure of
`M`" is formalized as: `tendsto u at_top (𝓝 x) → (∀ᶠ n in at_top, u n ∈ M) → x ∈ closure M`,
which is a special case of `mem_closure_of_tendsto` from topology.basic.
## Notations
* `∀ᶠ x in f, p x` : `f.eventually p`;
* `∃ᶠ x in f, p x` : `f.frequently p`;
* `f =ᶠ[l] g` : `∀ᶠ x in l, f x = g x`;
* `f ≤ᶠ[l] g` : `∀ᶠ x in l, f x ≤ g x`;
* `f ×ᶠ g` : `filter.prod f g`, localized in `filter`;
* `𝓟 s` : `principal s`, localized in `filter`.
## References
* [N. Bourbaki, *General Topology*][bourbaki1966]
Important note: Bourbaki requires that a filter on `X` cannot contain all sets of `X`, which
we do *not* require. This gives `filter X` better formal properties, in particular a bottom element
`⊥` for its lattice structure, at the cost of including the assumption
`[ne_bot f]` in a number of lemmas and definitions.
-/
open set function
universes u v w x y
open_locale classical
/-- A filter `F` on a type `α` is a collection of sets of `α` which contains the whole `α`,
is upwards-closed, and is stable under intersection. We do not forbid this collection to be
all sets of `α`. -/
structure filter (α : Type*) :=
(sets : set (set α))
(univ_sets : set.univ ∈ sets)
(sets_of_superset {x y} : x ∈ sets → x ⊆ y → y ∈ sets)
(inter_sets {x y} : x ∈ sets → y ∈ sets → x ∩ y ∈ sets)
/-- If `F` is a filter on `α`, and `U` a subset of `α` then we can write `U ∈ F` as on paper. -/
instance {α : Type*}: has_mem (set α) (filter α) := ⟨λ U F, U ∈ F.sets⟩
namespace filter
variables {α : Type u} {f g : filter α} {s t : set α}
@[simp] protected lemma mem_mk {t : set (set α)} {h₁ h₂ h₃} : s ∈ mk t h₁ h₂ h₃ ↔ s ∈ t := iff.rfl
@[simp] protected lemma mem_sets : s ∈ f.sets ↔ s ∈ f := iff.rfl
instance inhabited_mem : inhabited {s : set α // s ∈ f} := ⟨⟨univ, f.univ_sets⟩⟩
lemma filter_eq : ∀ {f g : filter α}, f.sets = g.sets → f = g
| ⟨a, _, _, _⟩ ⟨._, _, _, _⟩ rfl := rfl
lemma filter_eq_iff : f = g ↔ f.sets = g.sets :=
⟨congr_arg _, filter_eq⟩
protected lemma ext_iff : f = g ↔ ∀ s, s ∈ f ↔ s ∈ g :=
by simp only [filter_eq_iff, ext_iff, filter.mem_sets]
@[ext]
protected lemma ext : (∀ s, s ∈ f ↔ s ∈ g) → f = g :=
filter.ext_iff.2
@[simp] lemma univ_mem : univ ∈ f :=
f.univ_sets
lemma mem_of_superset {x y : set α} (hx : x ∈ f) (hxy : x ⊆ y) : y ∈ f :=
f.sets_of_superset hx hxy
lemma inter_mem {s t : set α} (hs : s ∈ f) (ht : t ∈ f) : s ∩ t ∈ f :=
f.inter_sets hs ht
@[simp] lemma inter_mem_iff {s t : set α} : s ∩ t ∈ f ↔ s ∈ f ∧ t ∈ f :=
⟨λ h, ⟨mem_of_superset h (inter_subset_left s t),
mem_of_superset h (inter_subset_right s t)⟩, and_imp.2 inter_mem⟩
lemma diff_mem {s t : set α} (hs : s ∈ f) (ht : tᶜ ∈ f) : s \ t ∈ f :=
inter_mem hs ht
lemma univ_mem' (h : ∀ a, a ∈ s) : s ∈ f :=
mem_of_superset univ_mem (λ x _, h x)
lemma mp_mem (hs : s ∈ f) (h : {x | x ∈ s → x ∈ t} ∈ f) : t ∈ f :=
mem_of_superset (inter_mem hs h) $ λ x ⟨h₁, h₂⟩, h₂ h₁
lemma congr_sets (h : {x | x ∈ s ↔ x ∈ t} ∈ f) : s ∈ f ↔ t ∈ f :=
⟨λ hs, mp_mem hs (mem_of_superset h (λ x, iff.mp)),
λ hs, mp_mem hs (mem_of_superset h (λ x, iff.mpr))⟩
@[simp] lemma bInter_mem {β : Type v} {s : β → set α} {is : set β} (hf : finite is) :
(⋂ i ∈ is, s i) ∈ f ↔ ∀ i ∈ is, s i ∈ f :=
finite.induction_on hf (by simp) (λ i s hi _ hs, by simp [hs])
@[simp] lemma bInter_finset_mem {β : Type v} {s : β → set α} (is : finset β) :
(⋂ i ∈ is, s i) ∈ f ↔ ∀ i ∈ is, s i ∈ f :=
bInter_mem is.finite_to_set
alias bInter_finset_mem ← finset.Inter_mem_sets
attribute [protected] finset.Inter_mem_sets
@[simp] lemma sInter_mem {s : set (set α)} (hfin : finite s) :
⋂₀ s ∈ f ↔ ∀ U ∈ s, U ∈ f :=
by rw [sInter_eq_bInter, bInter_mem hfin]
@[simp] lemma Inter_mem {β : Type v} {s : β → set α} [fintype β] :
(⋂ i, s i) ∈ f ↔ ∀ i, s i ∈ f :=
by simpa using bInter_mem finite_univ
lemma exists_mem_subset_iff : (∃ t ∈ f, t ⊆ s) ↔ s ∈ f :=
⟨λ ⟨t, ht, ts⟩, mem_of_superset ht ts, λ hs, ⟨s, hs, subset.rfl⟩⟩
lemma monotone_mem {f : filter α} : monotone (λ s, s ∈ f) :=
λ s t hst h, mem_of_superset h hst
end filter
namespace tactic.interactive
open tactic
setup_tactic_parser
/--
`filter_upwards [h₁, ⋯, hₙ]` replaces a goal of the form `s ∈ f` and terms
`h₁ : t₁ ∈ f, ⋯, hₙ : tₙ ∈ f` with `∀ x, x ∈ t₁ → ⋯ → x ∈ tₙ → x ∈ s`.
The list is an optional parameter, `[]` being its default value.
`filter_upwards [h₁, ⋯, hₙ] with a₁ a₂ ⋯ aₖ` is a short form for
`{ filter_upwards [h₁, ⋯, hₙ], intros a₁ a₂ ⋯ aₖ }`.
`filter_upwards [h₁, ⋯, hₙ] using e` is a short form for
`{ filter_upwards [h1, ⋯, hn], exact e }`.
Combining both shortcuts is done by writing `filter_upwards [h₁, ⋯, hₙ] with a₁ a₂ ⋯ aₖ using e`.
Note that in this case, the `aᵢ` terms can be used in `e`.
-/
meta def filter_upwards
(s : parse types.pexpr_list?)
(wth : parse with_ident_list?)
(tgt : parse (tk "using" *> texpr)?) : tactic unit :=
do
(s.get_or_else []).reverse.mmap (λ e, eapplyc `filter.mp_mem >> eapply e),
eapplyc `filter.univ_mem',
`[dsimp only [set.mem_set_of_eq]],
let wth := wth.get_or_else [],
if ¬wth.empty then intros wth else skip,
match tgt with
| some e := exact e
| none := skip
end
add_tactic_doc
{ name := "filter_upwards",
category := doc_category.tactic,
decl_names := [`tactic.interactive.filter_upwards],
tags := ["goal management", "lemma application"] }
end tactic.interactive
namespace filter
variables {α : Type u} {β : Type v} {γ : Type w} {ι : Sort x}
section principal
/-- The principal filter of `s` is the collection of all supersets of `s`. -/
def principal (s : set α) : filter α :=
{ sets := {t | s ⊆ t},
univ_sets := subset_univ s,
sets_of_superset := λ x y hx, subset.trans hx,
inter_sets := λ x y, subset_inter }
localized "notation `𝓟` := filter.principal" in filter
instance : inhabited (filter α) :=
⟨𝓟 ∅⟩
@[simp] lemma mem_principal {s t : set α} : s ∈ 𝓟 t ↔ t ⊆ s := iff.rfl
lemma mem_principal_self (s : set α) : s ∈ 𝓟 s := subset.rfl
end principal
open_locale filter
section join
/-- The join of a filter of filters is defined by the relation `s ∈ join f ↔ {t | s ∈ t} ∈ f`. -/
def join (f : filter (filter α)) : filter α :=
{ sets := {s | {t : filter α | s ∈ t} ∈ f},
univ_sets := by simp only [mem_set_of_eq, univ_sets, ← filter.mem_sets, set_of_true],
sets_of_superset := λ x y hx xy,
mem_of_superset hx $ λ f h, mem_of_superset h xy,
inter_sets := λ x y hx hy,
mem_of_superset (inter_mem hx hy) $ λ f ⟨h₁, h₂⟩, inter_mem h₁ h₂ }
@[simp] lemma mem_join {s : set α} {f : filter (filter α)} :
s ∈ join f ↔ {t | s ∈ t} ∈ f := iff.rfl
end join
section lattice
instance : partial_order (filter α) :=
{ le := λ f g, ∀ ⦃U : set α⦄, U ∈ g → U ∈ f,
le_antisymm := λ a b h₁ h₂, filter_eq $ subset.antisymm h₂ h₁,
le_refl := λ a, subset.rfl,
le_trans := λ a b c h₁ h₂, subset.trans h₂ h₁ }
theorem le_def {f g : filter α} : f ≤ g ↔ ∀ x ∈ g, x ∈ f := iff.rfl
/-- `generate_sets g s`: `s` is in the filter closure of `g`. -/
inductive generate_sets (g : set (set α)) : set α → Prop
| basic {s : set α} : s ∈ g → generate_sets s
| univ : generate_sets univ
| superset {s t : set α} : generate_sets s → s ⊆ t → generate_sets t
| inter {s t : set α} : generate_sets s → generate_sets t → generate_sets (s ∩ t)
/-- `generate g` is the smallest filter containing the sets `g`. -/
def generate (g : set (set α)) : filter α :=
{ sets := generate_sets g,
univ_sets := generate_sets.univ,
sets_of_superset := λ x y, generate_sets.superset,
inter_sets := λ s t, generate_sets.inter }
lemma sets_iff_generate {s : set (set α)} {f : filter α} : f ≤ filter.generate s ↔ s ⊆ f.sets :=
iff.intro
(λ h u hu, h $ generate_sets.basic $ hu)
(λ h u hu, hu.rec_on h univ_mem
(λ x y _ hxy hx, mem_of_superset hx hxy)
(λ x y _ _ hx hy, inter_mem hx hy))
lemma mem_generate_iff {s : set $ set α} {U : set α} :
U ∈ generate s ↔ ∃ t ⊆ s, finite t ∧ ⋂₀ t ⊆ U :=
begin
split ; intro h,
{ induction h with V V_in V W V_in hVW hV V W V_in W_in hV hW,
{ use {V},
simp [V_in] },
{ use ∅,
simp [subset.refl, univ] },
{ rcases hV with ⟨t, hts, htfin, hinter⟩,
exact ⟨t, hts, htfin, hinter.trans hVW⟩ },
{ rcases hV with ⟨t, hts, htfin, htinter⟩,
rcases hW with ⟨z, hzs, hzfin, hzinter⟩,
refine ⟨t ∪ z, union_subset hts hzs, htfin.union hzfin, _⟩,
rw sInter_union,
exact inter_subset_inter htinter hzinter } },
{ rcases h with ⟨t, ts, tfin, h⟩,
apply generate_sets.superset _ h,
revert ts,
apply finite.induction_on tfin,
{ intro h,
rw sInter_empty,
exact generate_sets.univ },
{ intros V r hV rfin hinter h,
cases insert_subset.mp h with V_in r_sub,
rw [insert_eq V r, sInter_union],
apply generate_sets.inter _ (hinter r_sub),
rw sInter_singleton,
exact generate_sets.basic V_in } },
end
/-- `mk_of_closure s hs` constructs a filter on `α` whose elements set is exactly
`s : set (set α)`, provided one gives the assumption `hs : (generate s).sets = s`. -/
protected def mk_of_closure (s : set (set α)) (hs : (generate s).sets = s) : filter α :=
{ sets := s,
univ_sets := hs ▸ (univ_mem : univ ∈ generate s),
sets_of_superset := λ x y, hs ▸ (mem_of_superset : x ∈ generate s → x ⊆ y → y ∈ generate s),
inter_sets := λ x y, hs ▸ (inter_mem : x ∈ generate s → y ∈ generate s →
x ∩ y ∈ generate s) }
lemma mk_of_closure_sets {s : set (set α)} {hs : (generate s).sets = s} :
filter.mk_of_closure s hs = generate s :=
filter.ext $ λ u,
show u ∈ (filter.mk_of_closure s hs).sets ↔ u ∈ (generate s).sets, from hs.symm ▸ iff.rfl
/-- Galois insertion from sets of sets into filters. -/
def gi_generate (α : Type*) :
@galois_insertion (set (set α)) (order_dual (filter α)) _ _ filter.generate filter.sets :=
{ gc := λ s f, sets_iff_generate,
le_l_u := λ f u h, generate_sets.basic h,
choice := λ s hs, filter.mk_of_closure s (le_antisymm hs $ sets_iff_generate.1 $ le_rfl),
choice_eq := λ s hs, mk_of_closure_sets }
/-- The infimum of filters is the filter generated by intersections
of elements of the two filters. -/
instance : has_inf (filter α) := ⟨λf g : filter α,
{ sets := {s | ∃ (a ∈ f) (b ∈ g), s = a ∩ b },
univ_sets := ⟨_, univ_mem, _, univ_mem, by simp⟩,
sets_of_superset := begin
rintro x y ⟨a, ha, b, hb, rfl⟩ xy,
refine ⟨a ∪ y, mem_of_superset ha (subset_union_left a y),
b ∪ y, mem_of_superset hb (subset_union_left b y), _⟩,
rw [← inter_union_distrib_right, union_eq_self_of_subset_left xy]
end,
inter_sets := begin
rintro x y ⟨a, ha, b, hb, rfl⟩ ⟨c, hc, d, hd, rfl⟩,
refine ⟨a ∩ c, inter_mem ha hc, b ∩ d, inter_mem hb hd, _⟩,
ac_refl
end }⟩
lemma mem_inf_iff {f g : filter α} {s : set α} :
s ∈ f ⊓ g ↔ ∃ t₁ ∈ f, ∃ t₂ ∈ g, s = t₁ ∩ t₂ := iff.rfl
lemma mem_inf_of_left {f g : filter α} {s : set α} (h : s ∈ f) : s ∈ f ⊓ g :=
⟨s, h, univ, univ_mem, (inter_univ s).symm⟩
lemma mem_inf_of_right {f g : filter α} {s : set α} (h : s ∈ g) : s ∈ f ⊓ g :=
⟨univ, univ_mem, s, h, (univ_inter s).symm⟩
lemma inter_mem_inf {α : Type u} {f g : filter α} {s t : set α}
(hs : s ∈ f) (ht : t ∈ g) : s ∩ t ∈ f ⊓ g :=
⟨s, hs, t, ht, rfl⟩
lemma mem_inf_of_inter {f g : filter α} {s t u : set α} (hs : s ∈ f) (ht : t ∈ g) (h : s ∩ t ⊆ u) :
u ∈ f ⊓ g :=
mem_of_superset (inter_mem_inf hs ht) h
lemma mem_inf_iff_superset {f g : filter α} {s : set α} :
s ∈ f ⊓ g ↔ ∃ t₁ ∈ f, ∃ t₂ ∈ g, t₁ ∩ t₂ ⊆ s :=
⟨λ ⟨t₁, h₁, t₂, h₂, eq⟩, ⟨t₁, h₁, t₂, h₂, eq ▸ subset.rfl⟩,
λ ⟨t₁, h₁, t₂, h₂, sub⟩, mem_inf_of_inter h₁ h₂ sub⟩
instance : has_top (filter α) :=
⟨{ sets := {s | ∀ x, x ∈ s},
univ_sets := λ x, mem_univ x,
sets_of_superset := λ x y hx hxy a, hxy (hx a),
inter_sets := λ x y hx hy a, mem_inter (hx _) (hy _) }⟩
lemma mem_top_iff_forall {s : set α} : s ∈ (⊤ : filter α) ↔ (∀ x, x ∈ s) :=
iff.rfl
@[simp] lemma mem_top {s : set α} : s ∈ (⊤ : filter α) ↔ s = univ :=
by rw [mem_top_iff_forall, eq_univ_iff_forall]
section complete_lattice
/- We lift the complete lattice along the Galois connection `generate` / `sets`. Unfortunately,
we want to have different definitional equalities for the lattice operations. So we define them
upfront and change the lattice operations for the complete lattice instance. -/
private def original_complete_lattice : complete_lattice (filter α) :=
@order_dual.complete_lattice _ (gi_generate α).lift_complete_lattice
local attribute [instance] original_complete_lattice
instance : complete_lattice (filter α) := original_complete_lattice.copy
/- le -/ filter.partial_order.le rfl
/- top -/ (filter.has_top).1
(top_unique $ λ s hs, by simp [mem_top.1 hs])
/- bot -/ _ rfl
/- sup -/ _ rfl
/- inf -/ (filter.has_inf).1
begin
ext f g : 2,
exact le_antisymm
(le_inf (λ s, mem_inf_of_left) (λ s, mem_inf_of_right))
(begin
rintro s ⟨a, ha, b, hb, rfl⟩,
exact inter_sets _ (@inf_le_left (filter α) _ _ _ _ ha)
(@inf_le_right (filter α) _ _ _ _ hb)
end)
end
/- Sup -/ (join ∘ 𝓟) (by { ext s x, exact mem_Inter₂.symm.trans
(set.ext_iff.1 (sInter_image _ _) x).symm})
/- Inf -/ _ rfl
end complete_lattice
/-- A filter is `ne_bot` if it is not equal to `⊥`, or equivalently the empty set
does not belong to the filter. Bourbaki include this assumption in the definition
of a filter but we prefer to have a `complete_lattice` structure on filter, so
we use a typeclass argument in lemmas instead. -/
class ne_bot (f : filter α) : Prop := (ne' : f ≠ ⊥)
lemma ne_bot_iff {f : filter α} : ne_bot f ↔ f ≠ ⊥ := ⟨λ h, h.1, λ h, ⟨h⟩⟩
lemma ne_bot.ne {f : filter α} (hf : ne_bot f) : f ≠ ⊥ := ne_bot.ne'
@[simp] lemma not_ne_bot {α : Type*} {f : filter α} : ¬ f.ne_bot ↔ f = ⊥ :=
not_iff_comm.1 ne_bot_iff.symm
lemma ne_bot.mono {f g : filter α} (hf : ne_bot f) (hg : f ≤ g) : ne_bot g :=
⟨ne_bot_of_le_ne_bot hf.1 hg⟩
lemma ne_bot_of_le {f g : filter α} [hf : ne_bot f] (hg : f ≤ g) : ne_bot g :=
hf.mono hg
@[simp] lemma sup_ne_bot {f g : filter α} : ne_bot (f ⊔ g) ↔ ne_bot f ∨ ne_bot g :=
by simp [ne_bot_iff, not_and_distrib]
lemma bot_sets_eq : (⊥ : filter α).sets = univ := rfl
lemma sup_sets_eq {f g : filter α} : (f ⊔ g).sets = f.sets ∩ g.sets :=
(gi_generate α).gc.u_inf
lemma Sup_sets_eq {s : set (filter α)} : (Sup s).sets = (⋂ f ∈ s, (f : filter α).sets) :=
(gi_generate α).gc.u_Inf
lemma supr_sets_eq {f : ι → filter α} : (supr f).sets = (⋂ i, (f i).sets) :=
(gi_generate α).gc.u_infi
lemma generate_empty : filter.generate ∅ = (⊤ : filter α) :=
(gi_generate α).gc.l_bot
lemma generate_univ : filter.generate univ = (⊥ : filter α) :=
mk_of_closure_sets.symm
lemma generate_union {s t : set (set α)} :
filter.generate (s ∪ t) = filter.generate s ⊓ filter.generate t :=
(gi_generate α).gc.l_sup
lemma generate_Union {s : ι → set (set α)} :
filter.generate (⋃ i, s i) = (⨅ i, filter.generate (s i)) :=
(gi_generate α).gc.l_supr
@[simp] lemma mem_bot {s : set α} : s ∈ (⊥ : filter α) :=
trivial
@[simp] lemma mem_sup {f g : filter α} {s : set α} :
s ∈ f ⊔ g ↔ s ∈ f ∧ s ∈ g :=
iff.rfl
lemma union_mem_sup {f g : filter α} {s t : set α} (hs : s ∈ f) (ht : t ∈ g) :
s ∪ t ∈ f ⊔ g :=
⟨mem_of_superset hs (subset_union_left s t), mem_of_superset ht (subset_union_right s t)⟩
@[simp] lemma mem_Sup {x : set α} {s : set (filter α)} :
x ∈ Sup s ↔ (∀ f ∈ s, x ∈ (f : filter α)) :=
iff.rfl
@[simp] lemma mem_supr {x : set α} {f : ι → filter α} :
x ∈ supr f ↔ (∀ i, x ∈ f i) :=
by simp only [← filter.mem_sets, supr_sets_eq, iff_self, mem_Inter]
@[simp] lemma supr_ne_bot {f : ι → filter α} : (⨆ i, f i).ne_bot ↔ ∃ i, (f i).ne_bot :=
by simp [ne_bot_iff]
lemma infi_eq_generate (s : ι → filter α) : infi s = generate (⋃ i, (s i).sets) :=
show generate _ = generate _, from congr_arg _ $ congr_arg Sup $ (range_comp _ _).symm
lemma mem_infi_of_mem {f : ι → filter α} (i : ι) : ∀ {s}, s ∈ f i → s ∈ ⨅ i, f i :=
show (⨅ i, f i) ≤ f i, from infi_le _ _
lemma mem_infi_of_Inter {ι} {s : ι → filter α} {U : set α} {I : set ι} (I_fin : finite I)
{V : I → set α} (hV : ∀ i, V i ∈ s i) (hU : (⋂ i, V i) ⊆ U) : U ∈ ⨅ i, s i :=
begin
haveI := I_fin.fintype,
refine mem_of_superset (Inter_mem.2 $ λ i, _) hU,
exact mem_infi_of_mem i (hV _)
end
lemma mem_infi {ι} {s : ι → filter α} {U : set α} : (U ∈ ⨅ i, s i) ↔
∃ I : set ι, finite I ∧ ∃ V : I → set α, (∀ i, V i ∈ s i) ∧ U = ⋂ i, V i :=
begin
split,
{ rw [infi_eq_generate, mem_generate_iff],
rintro ⟨t, tsub, tfin, tinter⟩,
rcases eq_finite_Union_of_finite_subset_Union tfin tsub with ⟨I, Ifin, σ, σfin, σsub, rfl⟩,
rw sInter_Union at tinter,
set V := λ i, U ∪ ⋂₀ σ i with hV,
have V_in : ∀ i, V i ∈ s i,
{ rintro i,
have : (⋂₀ σ i) ∈ s i,
{ rw sInter_mem (σfin _),
apply σsub },
exact mem_of_superset this (subset_union_right _ _) },
refine ⟨I, Ifin, V, V_in, _⟩,
rwa [hV, ← union_Inter, union_eq_self_of_subset_right] },
{ rintro ⟨I, Ifin, V, V_in, rfl⟩,
exact mem_infi_of_Inter Ifin V_in subset.rfl }
end
lemma mem_infi' {ι} {s : ι → filter α} {U : set α} : (U ∈ ⨅ i, s i) ↔
∃ I : set ι, finite I ∧ ∃ V : ι → set α, (∀ i, V i ∈ s i) ∧
(∀ i ∉ I, V i = univ) ∧ (U = ⋂ i ∈ I, V i) ∧ U = ⋂ i, V i :=
begin
simp only [mem_infi, set_coe.forall', bInter_eq_Inter],
refine ⟨_, λ ⟨I, If, V, hVs, _, hVU, _⟩, ⟨I, If, λ i, V i, λ i, hVs i, hVU⟩⟩,
rintro ⟨I, If, V, hV, rfl⟩,
refine ⟨I, If, λ i, if hi : i ∈ I then V ⟨i, hi⟩ else univ, λ i, _, λ i hi, _, _⟩,
{ split_ifs, exacts [hV _, univ_mem] },
{ exact dif_neg hi },
{ simp only [Inter_dite, bInter_eq_Inter, dif_pos (subtype.coe_prop _), subtype.coe_eta,
Inter_univ, inter_univ, eq_self_iff_true, true_and] }
end
lemma exists_Inter_of_mem_infi {ι : Type*} {α : Type*} {f : ι → filter α} {s}
(hs : s ∈ ⨅ i, f i) : ∃ t : ι → set α, (∀ i, t i ∈ f i) ∧ s = ⋂ i, t i :=
let ⟨I, If, V, hVs, hV', hVU, hVU'⟩ := mem_infi'.1 hs in ⟨V, hVs, hVU'⟩
lemma mem_infi_of_fintype {ι : Type*} [fintype ι] {α : Type*} {f : ι → filter α} (s) :
s ∈ (⨅ i, f i) ↔ ∃ t : ι → set α, (∀ i, t i ∈ f i) ∧ s = ⋂ i, t i :=
begin
refine ⟨exists_Inter_of_mem_infi, _⟩,
rintro ⟨t, ht, rfl⟩,
exact Inter_mem.2 (λ i, mem_infi_of_mem i (ht i))
end
@[simp] lemma le_principal_iff {s : set α} {f : filter α} : f ≤ 𝓟 s ↔ s ∈ f :=
show (∀ {t}, s ⊆ t → t ∈ f) ↔ s ∈ f,
from ⟨λ h, h (subset.refl s), λ hs t ht, mem_of_superset hs ht⟩
lemma principal_mono {s t : set α} : 𝓟 s ≤ 𝓟 t ↔ s ⊆ t :=
by simp only [le_principal_iff, iff_self, mem_principal]
@[mono] lemma monotone_principal : monotone (𝓟 : set α → filter α) :=
λ _ _, principal_mono.2
@[simp] lemma principal_eq_iff_eq {s t : set α} : 𝓟 s = 𝓟 t ↔ s = t :=
by simp only [le_antisymm_iff, le_principal_iff, mem_principal]; refl
@[simp] lemma join_principal_eq_Sup {s : set (filter α)} : join (𝓟 s) = Sup s := rfl
@[simp] lemma principal_univ : 𝓟 (univ : set α) = ⊤ :=
top_unique $ by simp only [le_principal_iff, mem_top, eq_self_iff_true]
@[simp] lemma principal_empty : 𝓟 (∅ : set α) = ⊥ :=
bot_unique $ λ s _, empty_subset _
lemma generate_eq_binfi (S : set (set α)) : generate S = ⨅ s ∈ S, 𝓟 s :=
eq_of_forall_le_iff $ λ f, by simp [sets_iff_generate, le_principal_iff, subset_def]
/-! ### Lattice equations -/
lemma empty_mem_iff_bot {f : filter α} : ∅ ∈ f ↔ f = ⊥ :=
⟨λ h, bot_unique $ λ s _, mem_of_superset h (empty_subset s),
λ h, h.symm ▸ mem_bot⟩
lemma nonempty_of_mem {f : filter α} [hf : ne_bot f] {s : set α} (hs : s ∈ f) :
s.nonempty :=
s.eq_empty_or_nonempty.elim (λ h, absurd hs (h.symm ▸ mt empty_mem_iff_bot.mp hf.1)) id
lemma ne_bot.nonempty_of_mem {f : filter α} (hf : ne_bot f) {s : set α} (hs : s ∈ f) :
s.nonempty :=
@nonempty_of_mem α f hf s hs
@[simp] lemma empty_not_mem (f : filter α) [ne_bot f] : ¬(∅ ∈ f) :=
λ h, (nonempty_of_mem h).ne_empty rfl
lemma nonempty_of_ne_bot (f : filter α) [ne_bot f] : nonempty α :=
nonempty_of_exists $ nonempty_of_mem (univ_mem : univ ∈ f)
lemma compl_not_mem {f : filter α} {s : set α} [ne_bot f] (h : s ∈ f) : sᶜ ∉ f :=
λ hsc, (nonempty_of_mem (inter_mem h hsc)).ne_empty $ inter_compl_self s
lemma filter_eq_bot_of_is_empty [is_empty α] (f : filter α) : f = ⊥ :=
empty_mem_iff_bot.mp $ univ_mem' is_empty_elim
protected lemma disjoint_iff {f g : filter α} :
disjoint f g ↔ ∃ (s ∈ f) (t ∈ g), disjoint s t :=
by simp only [disjoint_iff, ← empty_mem_iff_bot, mem_inf_iff,
inf_eq_inter, bot_eq_empty, @eq_comm _ ∅]
lemma disjoint_of_disjoint_of_mem {f g : filter α} {s t : set α} (h : disjoint s t)
(hs : s ∈ f) (ht : t ∈ g) : disjoint f g :=
filter.disjoint_iff.mpr ⟨s, hs, t, ht, h⟩
lemma inf_eq_bot_iff {f g : filter α} :
f ⊓ g = ⊥ ↔ ∃ (U ∈ f) (V ∈ g), U ∩ V = ∅ :=
by simpa only [disjoint_iff] using filter.disjoint_iff
/-- There is exactly one filter on an empty type. --/
-- TODO[gh-6025]: make this globally an instance once safe to do so
local attribute [instance]
protected def unique [is_empty α] : unique (filter α) :=
{ default := ⊥, uniq := filter_eq_bot_of_is_empty }
lemma forall_mem_nonempty_iff_ne_bot {f : filter α} :
(∀ (s : set α), s ∈ f → s.nonempty) ↔ ne_bot f :=
⟨λ h, ⟨λ hf, empty_not_nonempty (h ∅ $ hf.symm ▸ mem_bot)⟩, @nonempty_of_mem _ _⟩
lemma nontrivial_iff_nonempty : nontrivial (filter α) ↔ nonempty α :=
⟨λ ⟨⟨f, g, hfg⟩⟩, by_contra $
λ h, hfg $ by haveI : is_empty α := not_nonempty_iff.1 h; exact subsingleton.elim _ _,
λ ⟨x⟩, ⟨⟨⊤, ⊥, ne_bot.ne $ forall_mem_nonempty_iff_ne_bot.1 $ λ s hs,
by rwa [mem_top.1 hs, ← nonempty_iff_univ_nonempty]⟩⟩⟩
lemma eq_Inf_of_mem_iff_exists_mem {S : set (filter α)} {l : filter α}
(h : ∀ {s}, s ∈ l ↔ ∃ f ∈ S, s ∈ f) : l = Inf S :=
le_antisymm (le_Inf $ λ f hf s hs, h.2 ⟨f, hf, hs⟩)
(λ s hs, let ⟨f, hf, hs⟩ := h.1 hs in (Inf_le hf : Inf S ≤ f) hs)
lemma eq_infi_of_mem_iff_exists_mem {f : ι → filter α} {l : filter α}
(h : ∀ {s}, s ∈ l ↔ ∃ i, s ∈ f i) :
l = infi f :=
eq_Inf_of_mem_iff_exists_mem $ λ s, h.trans exists_range_iff.symm
lemma eq_binfi_of_mem_iff_exists_mem {f : ι → filter α} {p : ι → Prop} {l : filter α}
(h : ∀ {s}, s ∈ l ↔ ∃ i (_ : p i), s ∈ f i) :
l = ⨅ i (_ : p i), f i :=
begin
rw [infi_subtype'],
apply eq_infi_of_mem_iff_exists_mem,
intro s,
exact h.trans ⟨λ ⟨i, pi, si⟩, ⟨⟨i, pi⟩, si⟩, λ ⟨⟨i, pi⟩, si⟩, ⟨i, pi, si⟩⟩
end
lemma infi_sets_eq {f : ι → filter α} (h : directed (≥) f) [ne : nonempty ι] :
(infi f).sets = (⋃ i, (f i).sets) :=
let ⟨i⟩ := ne, u := { filter .
sets := (⋃ i, (f i).sets),
univ_sets := by simp only [mem_Union]; exact ⟨i, univ_mem⟩,
sets_of_superset := by simp only [mem_Union, exists_imp_distrib];
intros x y i hx hxy; exact ⟨i, mem_of_superset hx hxy⟩,
inter_sets :=
begin
simp only [mem_Union, exists_imp_distrib],
intros x y a hx b hy,
rcases h a b with ⟨c, ha, hb⟩,
exact ⟨c, inter_mem (ha hx) (hb hy)⟩
end } in
have u = infi f, from eq_infi_of_mem_iff_exists_mem
(λ s, by simp only [filter.mem_mk, mem_Union, filter.mem_sets]),
congr_arg filter.sets this.symm
lemma mem_infi_of_directed {f : ι → filter α} (h : directed (≥) f) [nonempty ι] (s) :
s ∈ infi f ↔ ∃ i, s ∈ f i :=
by simp only [← filter.mem_sets, infi_sets_eq h, mem_Union]
lemma mem_binfi_of_directed {f : β → filter α} {s : set β}
(h : directed_on (f ⁻¹'o (≥)) s) (ne : s.nonempty) {t : set α} :
t ∈ (⨅ i ∈ s, f i) ↔ ∃ i ∈ s, t ∈ f i :=
by haveI : nonempty {x // x ∈ s} := ne.to_subtype;
erw [infi_subtype', mem_infi_of_directed h.directed_coe, subtype.exists]; refl
lemma binfi_sets_eq {f : β → filter α} {s : set β}
(h : directed_on (f ⁻¹'o (≥)) s) (ne : s.nonempty) :
(⨅ i ∈ s, f i).sets = ⋃ i ∈ s, (f i).sets :=
ext $ λ t, by simp [mem_binfi_of_directed h ne]
lemma infi_sets_eq_finite {ι : Type*} (f : ι → filter α) :
(⨅ i, f i).sets = (⋃ t : finset ι, (⨅ i ∈ t, f i).sets) :=
begin
rw [infi_eq_infi_finset, infi_sets_eq],
exact (directed_of_sup $ λ s₁ s₂ hs, infi_le_infi $ λ i, infi_le_infi_const $ λ h, hs h),
end
lemma infi_sets_eq_finite' (f : ι → filter α) :
(⨅ i, f i).sets = (⋃ t : finset (plift ι), (⨅ i ∈ t, f (plift.down i)).sets) :=
by { rw [← infi_sets_eq_finite, ← equiv.plift.surjective.infi_comp], refl }
lemma mem_infi_finite {ι : Type*} {f : ι → filter α} (s) :
s ∈ infi f ↔ ∃ t : finset ι, s ∈ ⨅ i ∈ t, f i :=
(set.ext_iff.1 (infi_sets_eq_finite f) s).trans mem_Union
lemma mem_infi_finite' {f : ι → filter α} (s) :
s ∈ infi f ↔ ∃ t : finset (plift ι), s ∈ ⨅ i ∈ t, f (plift.down i) :=
(set.ext_iff.1 (infi_sets_eq_finite' f) s).trans mem_Union
@[simp] lemma sup_join {f₁ f₂ : filter (filter α)} : (join f₁ ⊔ join f₂) = join (f₁ ⊔ f₂) :=
filter.ext $ λ x, by simp only [mem_sup, mem_join]
@[simp] lemma supr_join {ι : Sort w} {f : ι → filter (filter α)} :
(⨆ x, join (f x)) = join (⨆ x, f x) :=
filter.ext $ λ x, by simp only [mem_supr, mem_join]
instance : distrib_lattice (filter α) :=
{ le_sup_inf :=
begin
intros x y z s,
simp only [and_assoc, mem_inf_iff, mem_sup, exists_prop, exists_imp_distrib, and_imp],
rintro hs t₁ ht₁ t₂ ht₂ rfl,
exact ⟨t₁, x.sets_of_superset hs (inter_subset_left t₁ t₂),
ht₁,
t₂,
x.sets_of_superset hs (inter_subset_right t₁ t₂),
ht₂,
rfl⟩
end,
..filter.complete_lattice }
/- the complementary version with ⨆ i, f ⊓ g i does not hold! -/
lemma infi_sup_left {f : filter α} {g : ι → filter α} : (⨅ x, f ⊔ g x) = f ⊔ infi g :=
begin
refine le_antisymm _ (le_infi $ λ i, sup_le_sup_left (infi_le _ _) _),
rintro t ⟨h₁, h₂⟩,
rw [infi_sets_eq_finite'] at h₂,
simp only [mem_Union, (finset.inf_eq_infi _ _).symm] at h₂,
rcases h₂ with ⟨s, hs⟩,
suffices : (⨅ i, f ⊔ g i) ≤ f ⊔ s.inf (λ i, g i.down), { exact this ⟨h₁, hs⟩ },
refine finset.induction_on s _ _,
{ exact le_sup_of_le_right le_top },
{ rintro ⟨i⟩ s his ih,
rw [finset.inf_insert, sup_inf_left],
exact le_inf (infi_le _ _) ih }
end
lemma infi_sup_right {f : filter α} {g : ι → filter α} : (⨅ x, g x ⊔ f) = infi g ⊔ f :=
by simp [sup_comm, ← infi_sup_left]
lemma binfi_sup_right (p : ι → Prop) (f : ι → filter α) (g : filter α) :
(⨅ i (h : p i), (f i ⊔ g)) = (⨅ i (h : p i), f i) ⊔ g :=
by rw [infi_subtype', infi_sup_right, infi_subtype']
lemma binfi_sup_left (p : ι → Prop) (f : ι → filter α) (g : filter α) :
(⨅ i (h : p i), (g ⊔ f i)) = g ⊔ (⨅ i (h : p i), f i) :=
by rw [infi_subtype', infi_sup_left, infi_subtype']
lemma mem_infi_finset {s : finset α} {f : α → filter β} {t : set β} :
t ∈ (⨅ a ∈ s, f a) ↔ (∃ p : α → set β, (∀ a ∈ s, p a ∈ f a) ∧ t = ⋂ a ∈ s, p a) :=
begin
simp only [← finset.set_bInter_coe, bInter_eq_Inter, infi_subtype'],
refine ⟨λ h, _, _⟩,
{ rcases (mem_infi_of_fintype _).1 h with ⟨p, hp, rfl⟩,
refine ⟨λ a, if h : a ∈ s then p ⟨a, h⟩ else univ, λ a ha, by simpa [ha] using hp ⟨a, ha⟩, _⟩,
refine Inter_congr_of_surjective id surjective_id _,
rintro ⟨a, ha⟩, simp [ha] },
{ rintro ⟨p, hpf, rfl⟩,
exact Inter_mem.2 (λ a, mem_infi_of_mem a (hpf a a.2)) }
end
/-- If `f : ι → filter α` is directed, `ι` is not empty, and `∀ i, f i ≠ ⊥`, then `infi f ≠ ⊥`.
See also `infi_ne_bot_of_directed` for a version assuming `nonempty α` instead of `nonempty ι`. -/
lemma infi_ne_bot_of_directed' {f : ι → filter α} [nonempty ι]
(hd : directed (≥) f) (hb : ∀ i, ne_bot (f i)) : ne_bot (infi f) :=
⟨begin
intro h,
have he : ∅ ∈ (infi f), from h.symm ▸ (mem_bot : ∅ ∈ (⊥ : filter α)),
obtain ⟨i, hi⟩ : ∃ i, ∅ ∈ f i,
from (mem_infi_of_directed hd ∅).1 he,
exact (hb i).ne (empty_mem_iff_bot.1 hi)
end⟩
/-- If `f : ι → filter α` is directed, `α` is not empty, and `∀ i, f i ≠ ⊥`, then `infi f ≠ ⊥`.
See also `infi_ne_bot_of_directed'` for a version assuming `nonempty ι` instead of `nonempty α`. -/
lemma infi_ne_bot_of_directed {f : ι → filter α}
[hn : nonempty α] (hd : directed (≥) f) (hb : ∀ i, ne_bot (f i)) : ne_bot (infi f) :=
if hι : nonempty ι then @infi_ne_bot_of_directed' _ _ _ hι hd hb else
⟨λ h : infi f = ⊥,
have univ ⊆ (∅ : set α),
begin
rw [←principal_mono, principal_univ, principal_empty, ←h],
exact (le_infi $ λ i, false.elim $ hι ⟨i⟩)
end,
let ⟨x⟩ := hn in this (mem_univ x)⟩
lemma infi_ne_bot_iff_of_directed' {f : ι → filter α} [nonempty ι] (hd : directed (≥) f) :
ne_bot (infi f) ↔ ∀ i, ne_bot (f i) :=
⟨λ H i, H.mono (infi_le _ i), infi_ne_bot_of_directed' hd⟩
lemma infi_ne_bot_iff_of_directed {f : ι → filter α} [nonempty α] (hd : directed (≥) f) :
ne_bot (infi f) ↔ (∀ i, ne_bot (f i)) :=
⟨λ H i, H.mono (infi_le _ i), infi_ne_bot_of_directed hd⟩
@[elab_as_eliminator]
lemma infi_sets_induct {f : ι → filter α} {s : set α} (hs : s ∈ infi f) {p : set α → Prop}
(uni : p univ)
(ins : ∀ {i s₁ s₂}, s₁ ∈ f i → p s₂ → p (s₁ ∩ s₂)) : p s :=
begin
rw [mem_infi_finite'] at hs,
simp only [← finset.inf_eq_infi] at hs,
rcases hs with ⟨is, his⟩,
revert s,
refine finset.induction_on is _ _,
{ intros s hs, rwa [mem_top.1 hs] },
{ rintro ⟨i⟩ js his ih s hs,
rw [finset.inf_insert, mem_inf_iff] at hs,
rcases hs with ⟨s₁, hs₁, s₂, hs₂, rfl⟩,
exact ins hs₁ (ih hs₂) }
end
/-! #### `principal` equations -/
@[simp] lemma inf_principal {s t : set α} : 𝓟 s ⊓ 𝓟 t = 𝓟 (s ∩ t) :=
le_antisymm
(by simp only [le_principal_iff, mem_inf_iff]; exact ⟨s, subset.rfl, t, subset.rfl, rfl⟩)
(by simp [le_inf_iff, inter_subset_left, inter_subset_right])
@[simp] lemma sup_principal {s t : set α} : 𝓟 s ⊔ 𝓟 t = 𝓟 (s ∪ t) :=
filter.ext $ λ u, by simp only [union_subset_iff, mem_sup, mem_principal]
@[simp] lemma supr_principal {ι : Sort w} {s : ι → set α} : (⨆ x, 𝓟 (s x)) = 𝓟 (⋃ i, s i) :=
filter.ext $ λ x, by simp only [mem_supr, mem_principal, Union_subset_iff]
@[simp] lemma principal_eq_bot_iff {s : set α} : 𝓟 s = ⊥ ↔ s = ∅ :=
empty_mem_iff_bot.symm.trans $ mem_principal.trans subset_empty_iff
@[simp] lemma principal_ne_bot_iff {s : set α} : ne_bot (𝓟 s) ↔ s.nonempty :=
ne_bot_iff.trans $ (not_congr principal_eq_bot_iff).trans ne_empty_iff_nonempty
lemma is_compl_principal (s : set α) : is_compl (𝓟 s) (𝓟 sᶜ) :=
⟨by simp only [inf_principal, inter_compl_self, principal_empty, le_refl],
by simp only [sup_principal, union_compl_self, principal_univ, le_refl]⟩
theorem mem_inf_principal' {f : filter α} {s t : set α} :
s ∈ f ⊓ 𝓟 t ↔ tᶜ ∪ s ∈ f :=
by simp only [← le_principal_iff, (is_compl_principal s).le_left_iff, disjoint_assoc, inf_principal,
← (is_compl_principal (t ∩ sᶜ)).le_right_iff, compl_inter, compl_compl]
theorem mem_inf_principal {f : filter α} {s t : set α} :
s ∈ f ⊓ 𝓟 t ↔ {x | x ∈ t → x ∈ s} ∈ f :=
by { simp only [mem_inf_principal', imp_iff_not_or], refl }
lemma supr_inf_principal (f : ι → filter α) (s : set α) :
(⨆ i, f i ⊓ 𝓟 s) = (⨆ i, f i) ⊓ 𝓟 s :=
by { ext, simp only [mem_supr, mem_inf_principal] }
lemma inf_principal_eq_bot {f : filter α} {s : set α} : f ⊓ 𝓟 s = ⊥ ↔ sᶜ ∈ f :=
by { rw [← empty_mem_iff_bot, mem_inf_principal], refl }
lemma mem_of_eq_bot {f : filter α} {s : set α} (h : f ⊓ 𝓟 sᶜ = ⊥) : s ∈ f :=
by rwa [inf_principal_eq_bot, compl_compl] at h
lemma diff_mem_inf_principal_compl {f : filter α} {s : set α} (hs : s ∈ f) (t : set α) :
s \ t ∈ f ⊓ 𝓟 tᶜ :=
inter_mem_inf hs $ mem_principal_self tᶜ
lemma principal_le_iff {s : set α} {f : filter α} :
𝓟 s ≤ f ↔ ∀ V ∈ f, s ⊆ V :=
begin
change (∀ V, V ∈ f → V ∈ _) ↔ _,
simp_rw mem_principal,
end
@[simp] lemma infi_principal_finset {ι : Type w} (s : finset ι) (f : ι → set α) :
(⨅ i ∈ s, 𝓟 (f i)) = 𝓟 (⋂ i ∈ s, f i) :=
begin
induction s using finset.induction_on with i s hi hs,
{ simp },
{ rw [finset.infi_insert, finset.set_bInter_insert, hs, inf_principal] },
end
@[simp] lemma infi_principal_fintype {ι : Type w} [fintype ι] (f : ι → set α) :
(⨅ i, 𝓟 (f i)) = 𝓟 (⋂ i, f i) :=
by simpa using infi_principal_finset finset.univ f
lemma infi_principal_finite {ι : Type w} {s : set ι} (hs : finite s) (f : ι → set α) :
(⨅ i ∈ s, 𝓟 (f i)) = 𝓟 (⋂ i ∈ s, f i) :=
begin
lift s to finset ι using hs,
exact_mod_cast infi_principal_finset s f
end
end lattice
@[mono] lemma join_mono {f₁ f₂ : filter (filter α)} (h : f₁ ≤ f₂) :
join f₁ ≤ join f₂ :=
λ s hs, h hs
/-! ### Eventually -/
/-- `f.eventually p` or `∀ᶠ x in f, p x` mean that `{x | p x} ∈ f`. E.g., `∀ᶠ x in at_top, p x`
means that `p` holds true for sufficiently large `x`. -/
protected def eventually (p : α → Prop) (f : filter α) : Prop := {x | p x} ∈ f
notation `∀ᶠ` binders ` in ` f `, ` r:(scoped p, filter.eventually p f) := r
lemma eventually_iff {f : filter α} {P : α → Prop} : (∀ᶠ x in f, P x) ↔ {x | P x} ∈ f :=
iff.rfl
@[simp] lemma eventually_mem_set {s : set α} {l : filter α} : (∀ᶠ x in l, x ∈ s) ↔ s ∈ l := iff.rfl
protected lemma ext' {f₁ f₂ : filter α}
(h : ∀ p : α → Prop, (∀ᶠ x in f₁, p x) ↔ (∀ᶠ x in f₂, p x)) :
f₁ = f₂ :=
filter.ext h
lemma eventually.filter_mono {f₁ f₂ : filter α} (h : f₁ ≤ f₂) {p : α → Prop}
(hp : ∀ᶠ x in f₂, p x) :
∀ᶠ x in f₁, p x :=
h hp
lemma eventually_of_mem {f : filter α} {P : α → Prop} {U : set α} (hU : U ∈ f) (h : ∀ x ∈ U, P x) :
∀ᶠ x in f, P x :=
mem_of_superset hU h
protected lemma eventually.and {p q : α → Prop} {f : filter α} :
f.eventually p → f.eventually q → ∀ᶠ x in f, p x ∧ q x :=
inter_mem
@[simp]
lemma eventually_true (f : filter α) : ∀ᶠ x in f, true := univ_mem
lemma eventually_of_forall {p : α → Prop} {f : filter α} (hp : ∀ x, p x) :
∀ᶠ x in f, p x :=
univ_mem' hp
@[simp] lemma eventually_false_iff_eq_bot {f : filter α} :
(∀ᶠ x in f, false) ↔ f = ⊥ :=
empty_mem_iff_bot
@[simp] lemma eventually_const {f : filter α} [t : ne_bot f] {p : Prop} :
(∀ᶠ x in f, p) ↔ p :=
classical.by_cases (λ h : p, by simp [h]) (λ h, by simpa [h] using t.ne)
lemma eventually_iff_exists_mem {p : α → Prop} {f : filter α} :
(∀ᶠ x in f, p x) ↔ ∃ v ∈ f, ∀ y ∈ v, p y :=
exists_mem_subset_iff.symm
lemma eventually.exists_mem {p : α → Prop} {f : filter α} (hp : ∀ᶠ x in f, p x) :
∃ v ∈ f, ∀ y ∈ v, p y :=
eventually_iff_exists_mem.1 hp
lemma eventually.mp {p q : α → Prop} {f : filter α} (hp : ∀ᶠ x in f, p x)
(hq : ∀ᶠ x in f, p x → q x) :
∀ᶠ x in f, q x :=
mp_mem hp hq
lemma eventually.mono {p q : α → Prop} {f : filter α} (hp : ∀ᶠ x in f, p x)
(hq : ∀ x, p x → q x) :
∀ᶠ x in f, q x :=
hp.mp (eventually_of_forall hq)
@[simp] lemma eventually_and {p q : α → Prop} {f : filter α} :
(∀ᶠ x in f, p x ∧ q x) ↔ (∀ᶠ x in f, p x) ∧ (∀ᶠ x in f, q x) :=
inter_mem_iff
lemma eventually.congr {f : filter α} {p q : α → Prop} (h' : ∀ᶠ x in f, p x)
(h : ∀ᶠ x in f, p x ↔ q x) : ∀ᶠ x in f, q x :=
h'.mp (h.mono $ λ x hx, hx.mp)
lemma eventually_congr {f : filter α} {p q : α → Prop} (h : ∀ᶠ x in f, p x ↔ q x) :
(∀ᶠ x in f, p x) ↔ (∀ᶠ x in f, q x) :=
⟨λ hp, hp.congr h, λ hq, hq.congr $ by simpa only [iff.comm] using h⟩
@[simp] lemma eventually_all {ι} [fintype ι] {l} {p : ι → α → Prop} :
(∀ᶠ x in l, ∀ i, p i x) ↔ ∀ i, ∀ᶠ x in l, p i x :=
by simpa only [filter.eventually, set_of_forall] using Inter_mem
@[simp] lemma eventually_all_finite {ι} {I : set ι} (hI : I.finite) {l} {p : ι → α → Prop} :
(∀ᶠ x in l, ∀ i ∈ I, p i x) ↔ (∀ i ∈ I, ∀ᶠ x in l, p i x) :=
by simpa only [filter.eventually, set_of_forall] using bInter_mem hI
alias eventually_all_finite ← set.finite.eventually_all
attribute [protected] set.finite.eventually_all
@[simp] lemma eventually_all_finset {ι} (I : finset ι) {l} {p : ι → α → Prop} :
(∀ᶠ x in l, ∀ i ∈ I, p i x) ↔ ∀ i ∈ I, ∀ᶠ x in l, p i x :=
I.finite_to_set.eventually_all
alias eventually_all_finset ← finset.eventually_all
attribute [protected] finset.eventually_all
@[simp] lemma eventually_or_distrib_left {f : filter α} {p : Prop} {q : α → Prop} :
(∀ᶠ x in f, p ∨ q x) ↔ (p ∨ ∀ᶠ x in f, q x) :=
classical.by_cases (λ h : p, by simp [h]) (λ h, by simp [h])
@[simp] lemma eventually_or_distrib_right {f : filter α} {p : α → Prop} {q : Prop} :
(∀ᶠ x in f, p x ∨ q) ↔ ((∀ᶠ x in f, p x) ∨ q) :=
by simp only [or_comm _ q, eventually_or_distrib_left]
@[simp] lemma eventually_imp_distrib_left {f : filter α} {p : Prop} {q : α → Prop} :
(∀ᶠ x in f, p → q x) ↔ (p → ∀ᶠ x in f, q x) :=
by simp only [imp_iff_not_or, eventually_or_distrib_left]
@[simp]
lemma eventually_bot {p : α → Prop} : ∀ᶠ x in ⊥, p x := ⟨⟩
@[simp]
lemma eventually_top {p : α → Prop} : (∀ᶠ x in ⊤, p x) ↔ (∀ x, p x) :=
iff.rfl
@[simp] lemma eventually_sup {p : α → Prop} {f g : filter α} :
(∀ᶠ x in f ⊔ g, p x) ↔ (∀ᶠ x in f, p x) ∧ (∀ᶠ x in g, p x) :=
iff.rfl
@[simp]
lemma eventually_Sup {p : α → Prop} {fs : set (filter α)} :
(∀ᶠ x in Sup fs, p x) ↔ (∀ f ∈ fs, ∀ᶠ x in f, p x) :=
iff.rfl
@[simp]
lemma eventually_supr {p : α → Prop} {fs : β → filter α} :
(∀ᶠ x in (⨆ b, fs b), p x) ↔ (∀ b, ∀ᶠ x in fs b, p x) :=
mem_supr
@[simp]
lemma eventually_principal {a : set α} {p : α → Prop} :
(∀ᶠ x in 𝓟 a, p x) ↔ (∀ x ∈ a, p x) :=
iff.rfl
lemma eventually_inf {f g : filter α} {p : α → Prop} :
(∀ᶠ x in f ⊓ g, p x) ↔ ∃ (s ∈ f) (t ∈ g), ∀ x ∈ s ∩ t, p x :=
mem_inf_iff_superset
theorem eventually_inf_principal {f : filter α} {p : α → Prop} {s : set α} :
(∀ᶠ x in f ⊓ 𝓟 s, p x) ↔ ∀ᶠ x in f, x ∈ s → p x :=
mem_inf_principal
/-! ### Frequently -/
/-- `f.frequently p` or `∃ᶠ x in f, p x` mean that `{x | ¬p x} ∉ f`. E.g., `∃ᶠ x in at_top, p x`
means that there exist arbitrarily large `x` for which `p` holds true. -/
protected def frequently (p : α → Prop) (f : filter α) : Prop := ¬∀ᶠ x in f, ¬p x
notation `∃ᶠ` binders ` in ` f `, ` r:(scoped p, filter.frequently p f) := r
lemma eventually.frequently {f : filter α} [ne_bot f] {p : α → Prop} (h : ∀ᶠ x in f, p x) :
∃ᶠ x in f, p x :=
compl_not_mem h
lemma frequently_of_forall {f : filter α} [ne_bot f] {p : α → Prop} (h : ∀ x, p x) :
∃ᶠ x in f, p x :=
eventually.frequently (eventually_of_forall h)
lemma frequently.mp {p q : α → Prop} {f : filter α} (h : ∃ᶠ x in f, p x)
(hpq : ∀ᶠ x in f, p x → q x) :
∃ᶠ x in f, q x :=
mt (λ hq, hq.mp $ hpq.mono $ λ x, mt) h
lemma frequently.filter_mono {p : α → Prop} {f g : filter α} (h : ∃ᶠ x in f, p x) (hle : f ≤ g) :
∃ᶠ x in g, p x :=
mt (λ h', h'.filter_mono hle) h
lemma frequently.mono {p q : α → Prop} {f : filter α} (h : ∃ᶠ x in f, p x)
(hpq : ∀ x, p x → q x) :
∃ᶠ x in f, q x :=
h.mp (eventually_of_forall hpq)
lemma frequently.and_eventually {p q : α → Prop} {f : filter α}
(hp : ∃ᶠ x in f, p x) (hq : ∀ᶠ x in f, q x) :
∃ᶠ x in f, p x ∧ q x :=
begin
refine mt (λ h, hq.mp $ h.mono _) hp,
exact λ x hpq hq hp, hpq ⟨hp, hq⟩
end
lemma eventually.and_frequently {p q : α → Prop} {f : filter α}
(hp : ∀ᶠ x in f, p x) (hq : ∃ᶠ x in f, q x) :
∃ᶠ x in f, p x ∧ q x :=
by simpa only [and.comm] using hq.and_eventually hp
lemma frequently.exists {p : α → Prop} {f : filter α} (hp : ∃ᶠ x in f, p x) : ∃ x, p x :=
begin
by_contradiction H,
replace H : ∀ᶠ x in f, ¬ p x, from eventually_of_forall (not_exists.1 H),
exact hp H
end
lemma eventually.exists {p : α → Prop} {f : filter α} [ne_bot f] (hp : ∀ᶠ x in f, p x) :
∃ x, p x :=
hp.frequently.exists
lemma frequently_iff_forall_eventually_exists_and {p : α → Prop} {f : filter α} :
(∃ᶠ x in f, p x) ↔ ∀ {q : α → Prop}, (∀ᶠ x in f, q x) → ∃ x, p x ∧ q x :=
⟨λ hp q hq, (hp.and_eventually hq).exists,
λ H hp, by simpa only [and_not_self, exists_false] using H hp⟩
lemma frequently_iff {f : filter α} {P : α → Prop} :
(∃ᶠ x in f, P x) ↔ ∀ {U}, U ∈ f → ∃ x ∈ U, P x :=
begin
simp only [frequently_iff_forall_eventually_exists_and, exists_prop, and_comm (P _)],
refl
end
@[simp] lemma not_eventually {p : α → Prop} {f : filter α} :
(¬ ∀ᶠ x in f, p x) ↔ (∃ᶠ x in f, ¬ p x) :=
by simp [filter.frequently]
@[simp] lemma not_frequently {p : α → Prop} {f : filter α} :
(¬ ∃ᶠ x in f, p x) ↔ (∀ᶠ x in f, ¬ p x) :=
by simp only [filter.frequently, not_not]
@[simp] lemma frequently_true_iff_ne_bot (f : filter α) : (∃ᶠ x in f, true) ↔ ne_bot f :=
by simp [filter.frequently, -not_eventually, eventually_false_iff_eq_bot, ne_bot_iff]
@[simp] lemma frequently_false (f : filter α) : ¬ ∃ᶠ x in f, false := by simp
@[simp] lemma frequently_const {f : filter α} [ne_bot f] {p : Prop} :
(∃ᶠ x in f, p) ↔ p :=
classical.by_cases (λ h : p, by simpa [h]) (λ h, by simp [h])
@[simp] lemma frequently_or_distrib {f : filter α} {p q : α → Prop} :
(∃ᶠ x in f, p x ∨ q x) ↔ (∃ᶠ x in f, p x) ∨ (∃ᶠ x in f, q x) :=
by simp only [filter.frequently, ← not_and_distrib, not_or_distrib, eventually_and]
lemma frequently_or_distrib_left {f : filter α} [ne_bot f] {p : Prop} {q : α → Prop} :
(∃ᶠ x in f, p ∨ q x) ↔ (p ∨ ∃ᶠ x in f, q x) :=
by simp
lemma frequently_or_distrib_right {f : filter α} [ne_bot f] {p : α → Prop} {q : Prop} :
(∃ᶠ x in f, p x ∨ q) ↔ (∃ᶠ x in f, p x) ∨ q :=
by simp
@[simp] lemma frequently_imp_distrib {f : filter α} {p q : α → Prop} :
(∃ᶠ x in f, p x → q x) ↔ ((∀ᶠ x in f, p x) → ∃ᶠ x in f, q x) :=
by simp [imp_iff_not_or, not_eventually, frequently_or_distrib]
lemma frequently_imp_distrib_left {f : filter α} [ne_bot f] {p : Prop} {q : α → Prop} :
(∃ᶠ x in f, p → q x) ↔ (p → ∃ᶠ x in f, q x) :=
by simp
lemma frequently_imp_distrib_right {f : filter α} [ne_bot f] {p : α → Prop} {q : Prop} :
(∃ᶠ x in f, p x → q) ↔ ((∀ᶠ x in f, p x) → q) :=
by simp
@[simp] lemma eventually_imp_distrib_right {f : filter α} {p : α → Prop} {q : Prop} :
(∀ᶠ x in f, p x → q) ↔ ((∃ᶠ x in f, p x) → q) :=
by simp only [imp_iff_not_or, eventually_or_distrib_right, not_frequently]
@[simp] lemma frequently_and_distrib_left {f : filter α} {p : Prop} {q : α → Prop} :
(∃ᶠ x in f, p ∧ q x) ↔ (p ∧ ∃ᶠ x in f, q x) :=
by simp only [filter.frequently, not_and, eventually_imp_distrib_left, not_imp]
@[simp] lemma frequently_and_distrib_right {f : filter α} {p : α → Prop} {q : Prop} :
(∃ᶠ x in f, p x ∧ q) ↔ ((∃ᶠ x in f, p x) ∧ q) :=
by simp only [and_comm _ q, frequently_and_distrib_left]
@[simp] lemma frequently_bot {p : α → Prop} : ¬ ∃ᶠ x in ⊥, p x := by simp
@[simp]
lemma frequently_top {p : α → Prop} : (∃ᶠ x in ⊤, p x) ↔ (∃ x, p x) :=
by simp [filter.frequently]
@[simp]
lemma frequently_principal {a : set α} {p : α → Prop} :
(∃ᶠ x in 𝓟 a, p x) ↔ (∃ x ∈ a, p x) :=
by simp [filter.frequently, not_forall]
lemma frequently_sup {p : α → Prop} {f g : filter α} :
(∃ᶠ x in f ⊔ g, p x) ↔ (∃ᶠ x in f, p x) ∨ (∃ᶠ x in g, p x) :=
by simp only [filter.frequently, eventually_sup, not_and_distrib]
@[simp]
lemma frequently_Sup {p : α → Prop} {fs : set (filter α)} :
(∃ᶠ x in Sup fs, p x) ↔ (∃ f ∈ fs, ∃ᶠ x in f, p x) :=
by simp [filter.frequently, -not_eventually, not_forall]
@[simp]
lemma frequently_supr {p : α → Prop} {fs : β → filter α} :
(∃ᶠ x in (⨆ b, fs b), p x) ↔ (∃ b, ∃ᶠ x in fs b, p x) :=
by simp [filter.frequently, -not_eventually, not_forall]
/-!
### Relation “eventually equal”
-/
/-- Two functions `f` and `g` are *eventually equal* along a filter `l` if the set of `x` such that
`f x = g x` belongs to `l`. -/
def eventually_eq (l : filter α) (f g : α → β) : Prop := ∀ᶠ x in l, f x = g x
notation f ` =ᶠ[`:50 l:50 `] `:0 g:50 := eventually_eq l f g
lemma eventually_eq.eventually {l : filter α} {f g : α → β} (h : f =ᶠ[l] g) :
∀ᶠ x in l, f x = g x :=
h
lemma eventually_eq.rw {l : filter α} {f g : α → β} (h : f =ᶠ[l] g) (p : α → β → Prop)
(hf : ∀ᶠ x in l, p x (f x)) :
∀ᶠ x in l, p x (g x) :=
hf.congr $ h.mono $ λ x hx, hx ▸ iff.rfl
lemma eventually_eq_set {s t : set α} {l : filter α} :
s =ᶠ[l] t ↔ ∀ᶠ x in l, x ∈ s ↔ x ∈ t :=
eventually_congr $ eventually_of_forall $ λ x, ⟨eq.to_iff, iff.to_eq⟩
alias eventually_eq_set ↔ filter.eventually_eq.mem_iff filter.eventually.set_eq
@[simp] lemma eventually_eq_univ {s : set α} {l : filter α} : s =ᶠ[l] univ ↔ s ∈ l :=
by simp [eventually_eq_set]
lemma eventually_eq.exists_mem {l : filter α} {f g : α → β} (h : f =ᶠ[l] g) :
∃ s ∈ l, eq_on f g s :=
h.exists_mem
lemma eventually_eq_of_mem {l : filter α} {f g : α → β} {s : set α}
(hs : s ∈ l) (h : eq_on f g s) : f =ᶠ[l] g :=
eventually_of_mem hs h
lemma eventually_eq_iff_exists_mem {l : filter α} {f g : α → β} :
(f =ᶠ[l] g) ↔ ∃ s ∈ l, eq_on f g s :=
eventually_iff_exists_mem
lemma eventually_eq.filter_mono {l l' : filter α} {f g : α → β} (h₁ : f =ᶠ[l] g) (h₂ : l' ≤ l) :
f =ᶠ[l'] g :=
h₂ h₁
@[refl] lemma eventually_eq.refl (l : filter α) (f : α → β) :
f =ᶠ[l] f :=
eventually_of_forall $ λ x, rfl
lemma eventually_eq.rfl {l : filter α} {f : α → β} : f =ᶠ[l] f := eventually_eq.refl l f
@[symm] lemma eventually_eq.symm {f g : α → β} {l : filter α} (H : f =ᶠ[l] g) :
g =ᶠ[l] f :=
H.mono $ λ _, eq.symm
@[trans] lemma eventually_eq.trans {f g h : α → β} {l : filter α}
(H₁ : f =ᶠ[l] g) (H₂ : g =ᶠ[l] h) :
f =ᶠ[l] h :=
H₂.rw (λ x y, f x = y) H₁
lemma eventually_eq.prod_mk {l} {f f' : α → β} (hf : f =ᶠ[l] f') {g g' : α → γ} (hg : g =ᶠ[l] g') :
(λ x, (f x, g x)) =ᶠ[l] (λ x, (f' x, g' x)) :=
hf.mp $ hg.mono $ by { intros, simp only * }
lemma eventually_eq.fun_comp {f g : α → β} {l : filter α} (H : f =ᶠ[l] g) (h : β → γ) :
(h ∘ f) =ᶠ[l] (h ∘ g) :=
H.mono $ λ x hx, congr_arg h hx
lemma eventually_eq.comp₂ {δ} {f f' : α → β} {g g' : α → γ} {l} (Hf : f =ᶠ[l] f') (h : β → γ → δ)
(Hg : g =ᶠ[l] g') :
(λ x, h (f x) (g x)) =ᶠ[l] (λ x, h (f' x) (g' x)) :=
(Hf.prod_mk Hg).fun_comp (uncurry h)
@[to_additive]
lemma eventually_eq.mul [has_mul β] {f f' g g' : α → β} {l : filter α} (h : f =ᶠ[l] g)
(h' : f' =ᶠ[l] g') :
((λ x, f x * f' x) =ᶠ[l] (λ x, g x * g' x)) :=
h.comp₂ (*) h'
@[to_additive]
lemma eventually_eq.inv [has_inv β] {f g : α → β} {l : filter α} (h : f =ᶠ[l] g) :
((λ x, (f x)⁻¹) =ᶠ[l] (λ x, (g x)⁻¹)) :=
h.fun_comp has_inv.inv
lemma eventually_eq.div [group_with_zero β] {f f' g g' : α → β} {l : filter α} (h : f =ᶠ[l] g)
(h' : f' =ᶠ[l] g') :
((λ x, f x / f' x) =ᶠ[l] (λ x, g x / g' x)) :=
by simpa only [div_eq_mul_inv] using h.mul h'.inv
lemma eventually_eq.div' [group β] {f f' g g' : α → β} {l : filter α} (h : f =ᶠ[l] g)
(h' : f' =ᶠ[l] g') :
((λ x, f x / f' x) =ᶠ[l] (λ x, g x / g' x)) :=
by simpa only [div_eq_mul_inv] using h.mul h'.inv
lemma eventually_eq.sub [add_group β] {f f' g g' : α → β} {l : filter α} (h : f =ᶠ[l] g)
(h' : f' =ᶠ[l] g') :
((λ x, f x - f' x) =ᶠ[l] (λ x, g x - g' x)) :=
by simpa only [sub_eq_add_neg] using h.add h'.neg
lemma eventually_eq.inter {s t s' t' : set α} {l : filter α} (h : s =ᶠ[l] t) (h' : s' =ᶠ[l] t') :
(s ∩ s' : set α) =ᶠ[l] (t ∩ t' : set α) :=
h.comp₂ (∧) h'
lemma eventually_eq.union {s t s' t' : set α} {l : filter α} (h : s =ᶠ[l] t) (h' : s' =ᶠ[l] t') :
(s ∪ s' : set α) =ᶠ[l] (t ∪ t' : set α) :=
h.comp₂ (∨) h'
lemma eventually_eq.compl {s t : set α} {l : filter α} (h : s =ᶠ[l] t) :
(sᶜ : set α) =ᶠ[l] (tᶜ : set α) :=
h.fun_comp not
lemma eventually_eq.diff {s t s' t' : set α} {l : filter α} (h : s =ᶠ[l] t) (h' : s' =ᶠ[l] t') :
(s \ s' : set α) =ᶠ[l] (t \ t' : set α) :=
h.inter h'.compl
lemma eventually_eq_empty {s : set α} {l : filter α} :
s =ᶠ[l] (∅ : set α) ↔ ∀ᶠ x in l, x ∉ s :=
eventually_eq_set.trans $ by simp
lemma inter_eventually_eq_left {s t : set α} {l : filter α} :
(s ∩ t : set α) =ᶠ[l] s ↔ ∀ᶠ x in l, x ∈ s → x ∈ t :=
by simp only [eventually_eq_set, mem_inter_eq, and_iff_left_iff_imp]
lemma inter_eventually_eq_right {s t : set α} {l : filter α} :
(s ∩ t : set α) =ᶠ[l] t ↔ ∀ᶠ x in l, x ∈ t → x ∈ s :=
by rw [inter_comm, inter_eventually_eq_left]
@[simp] lemma eventually_eq_principal {s : set α} {f g : α → β} :
f =ᶠ[𝓟 s] g ↔ eq_on f g s :=
iff.rfl
lemma eventually_eq_inf_principal_iff {F : filter α} {s : set α} {f g : α → β} :
(f =ᶠ[F ⊓ 𝓟 s] g) ↔ ∀ᶠ x in F, x ∈ s → f x = g x :=
eventually_inf_principal
lemma eventually_eq.sub_eq [add_group β] {f g : α → β} {l : filter α} (h : f =ᶠ[l] g) :
f - g =ᶠ[l] 0 :=
by simpa using (eventually_eq.sub (eventually_eq.refl l f) h).symm
lemma eventually_eq_iff_sub [add_group β] {f g : α → β} {l : filter α} :
f =ᶠ[l] g ↔ f - g =ᶠ[l] 0 :=
⟨λ h, h.sub_eq, λ h, by simpa using h.add (eventually_eq.refl l g)⟩
section has_le
variables [has_le β] {l : filter α}
/-- A function `f` is eventually less than or equal to a function `g` at a filter `l`. -/
def eventually_le (l : filter α) (f g : α → β) : Prop := ∀ᶠ x in l, f x ≤ g x
notation f ` ≤ᶠ[`:50 l:50 `] `:0 g:50 := eventually_le l f g
lemma eventually_le.congr {f f' g g' : α → β} (H : f ≤ᶠ[l] g) (hf : f =ᶠ[l] f') (hg : g =ᶠ[l] g') :
f' ≤ᶠ[l] g' :=
H.mp $ hg.mp $ hf.mono $ λ x hf hg H, by rwa [hf, hg] at H
lemma eventually_le_congr {f f' g g' : α → β} (hf : f =ᶠ[l] f') (hg : g =ᶠ[l] g') :
f ≤ᶠ[l] g ↔ f' ≤ᶠ[l] g' :=
⟨λ H, H.congr hf hg, λ H, H.congr hf.symm hg.symm⟩
end has_le
section preorder
variables [preorder β] {l : filter α} {f g h : α → β}
lemma eventually_eq.le (h : f =ᶠ[l] g) : f ≤ᶠ[l] g := h.mono $ λ x, le_of_eq
@[refl] lemma eventually_le.refl (l : filter α) (f : α → β) :
f ≤ᶠ[l] f :=
eventually_eq.rfl.le
lemma eventually_le.rfl : f ≤ᶠ[l] f := eventually_le.refl l f
@[trans] lemma eventually_le.trans (H₁ : f ≤ᶠ[l] g) (H₂ : g ≤ᶠ[l] h) : f ≤ᶠ[l] h :=
H₂.mp $ H₁.mono $ λ x, le_trans
@[trans] lemma eventually_eq.trans_le (H₁ : f =ᶠ[l] g) (H₂ : g ≤ᶠ[l] h) : f ≤ᶠ[l] h :=
H₁.le.trans H₂
@[trans] lemma eventually_le.trans_eq (H₁ : f ≤ᶠ[l] g) (H₂ : g =ᶠ[l] h) : f ≤ᶠ[l] h :=
H₁.trans H₂.le
end preorder
lemma eventually_le.antisymm [partial_order β] {l : filter α} {f g : α → β}
(h₁ : f ≤ᶠ[l] g) (h₂ : g ≤ᶠ[l] f) :
f =ᶠ[l] g :=
h₂.mp $ h₁.mono $ λ x, le_antisymm
lemma eventually_le_antisymm_iff [partial_order β] {l : filter α} {f g : α → β} :
f =ᶠ[l] g ↔ f ≤ᶠ[l] g ∧ g ≤ᶠ[l] f :=
by simp only [eventually_eq, eventually_le, le_antisymm_iff, eventually_and]
lemma eventually_le.le_iff_eq [partial_order β] {l : filter α} {f g : α → β} (h : f ≤ᶠ[l] g) :
g ≤ᶠ[l] f ↔ g =ᶠ[l] f :=
⟨λ h', h'.antisymm h, eventually_eq.le⟩
lemma eventually.ne_of_lt [preorder β] {l : filter α} {f g : α → β}
(h : ∀ᶠ x in l, f x < g x) : ∀ᶠ x in l, f x ≠ g x :=
h.mono (λ x hx, hx.ne)
lemma eventually.ne_top_of_lt [partial_order β] [order_top β] {l : filter α} {f g : α → β}
(h : ∀ᶠ x in l, f x < g x) : ∀ᶠ x in l, f x ≠ ⊤ :=
h.mono (λ x hx, hx.ne_top)
lemma eventually.lt_top_of_ne [partial_order β] [order_top β] {l : filter α} {f : α → β}
(h : ∀ᶠ x in l, f x ≠ ⊤) : ∀ᶠ x in l, f x < ⊤ :=
h.mono (λ x hx, hx.lt_top)
lemma eventually.lt_top_iff_ne_top [partial_order β] [order_top β] {l : filter α} {f : α → β} :
(∀ᶠ x in l, f x < ⊤) ↔ ∀ᶠ x in l, f x ≠ ⊤ :=
⟨eventually.ne_of_lt, eventually.lt_top_of_ne⟩
@[mono] lemma eventually_le.inter {s t s' t' : set α} {l : filter α} (h : s ≤ᶠ[l] t)
(h' : s' ≤ᶠ[l] t') :
(s ∩ s' : set α) ≤ᶠ[l] (t ∩ t' : set α) :=
h'.mp $ h.mono $ λ x, and.imp
@[mono] lemma eventually_le.union {s t s' t' : set α} {l : filter α} (h : s ≤ᶠ[l] t)
(h' : s' ≤ᶠ[l] t') :
(s ∪ s' : set α) ≤ᶠ[l] (t ∪ t' : set α) :=
h'.mp $ h.mono $ λ x, or.imp
@[mono] lemma eventually_le.compl {s t : set α} {l : filter α} (h : s ≤ᶠ[l] t) :
(tᶜ : set α) ≤ᶠ[l] (sᶜ : set α) :=
h.mono $ λ x, mt
@[mono] lemma eventually_le.diff {s t s' t' : set α} {l : filter α} (h : s ≤ᶠ[l] t)
(h' : t' ≤ᶠ[l] s') :
(s \ s' : set α) ≤ᶠ[l] (t \ t' : set α) :=
h.inter h'.compl
lemma join_le {f : filter (filter α)} {l : filter α} (h : ∀ᶠ m in f, m ≤ l) : join f ≤ l :=
λ s hs, h.mono $ λ m hm, hm hs
/-! ### Push-forwards, pull-backs, and the monad structure -/
section map
/-- The forward map of a filter -/
def map (m : α → β) (f : filter α) : filter β :=
{ sets := preimage m ⁻¹' f.sets,
univ_sets := univ_mem,
sets_of_superset := λ s t hs st, mem_of_superset hs $ preimage_mono st,
inter_sets := λ s t hs ht, inter_mem hs ht }
@[simp] lemma map_principal {s : set α} {f : α → β} :
map f (𝓟 s) = 𝓟 (set.image f s) :=
filter.ext $ λ a, image_subset_iff.symm
variables {f : filter α} {m : α → β} {m' : β → γ} {s : set α} {t : set β}
@[simp] lemma eventually_map {P : β → Prop} :
(∀ᶠ b in map m f, P b) ↔ ∀ᶠ a in f, P (m a) :=
iff.rfl
@[simp] lemma frequently_map {P : β → Prop} :
(∃ᶠ b in map m f, P b) ↔ ∃ᶠ a in f, P (m a) :=
iff.rfl
@[simp] lemma mem_map : t ∈ map m f ↔ m ⁻¹' t ∈ f := iff.rfl
lemma mem_map' : t ∈ map m f ↔ {x | m x ∈ t} ∈ f := iff.rfl
lemma image_mem_map (hs : s ∈ f) : m '' s ∈ map m f :=
f.sets_of_superset hs $ subset_preimage_image m s
lemma image_mem_map_iff (hf : injective m) : m '' s ∈ map m f ↔ s ∈ f :=
⟨λ h, by rwa [← preimage_image_eq s hf], image_mem_map⟩
lemma range_mem_map : range m ∈ map m f :=
by { rw ←image_univ, exact image_mem_map univ_mem }
lemma mem_map_iff_exists_image : t ∈ map m f ↔ (∃ s ∈ f, m '' s ⊆ t) :=
⟨λ ht, ⟨m ⁻¹' t, ht, image_preimage_subset _ _⟩,
λ ⟨s, hs, ht⟩, mem_of_superset (image_mem_map hs) ht⟩
@[simp] lemma map_id : filter.map id f = f :=
filter_eq $ rfl
@[simp] lemma map_id' : filter.map (λ x, x) f = f := map_id
@[simp] lemma map_compose : filter.map m' ∘ filter.map m = filter.map (m' ∘ m) :=
funext $ λ _, filter_eq $ rfl
@[simp] lemma map_map : filter.map m' (filter.map m f) = filter.map (m' ∘ m) f :=
congr_fun (@@filter.map_compose m m') f
/-- If functions `m₁` and `m₂` are eventually equal at a filter `f`, then
they map this filter to the same filter. -/
lemma map_congr {m₁ m₂ : α → β} {f : filter α} (h : m₁ =ᶠ[f] m₂) :
map m₁ f = map m₂ f :=
filter.ext' $ λ p,
by { simp only [eventually_map], exact eventually_congr (h.mono $ λ x hx, hx ▸ iff.rfl) }
end map
section comap
/-- The inverse map of a filter -/
def comap (m : α → β) (f : filter β) : filter α :=
{ sets := { s | ∃ t ∈ f, m ⁻¹' t ⊆ s },
univ_sets := ⟨univ, univ_mem, by simp only [subset_univ, preimage_univ]⟩,
sets_of_superset := λ a b ⟨a', ha', ma'a⟩ ab, ⟨a', ha', ma'a.trans ab⟩,
inter_sets := λ a b ⟨a', ha₁, ha₂⟩ ⟨b', hb₁, hb₂⟩,
⟨a' ∩ b', inter_mem ha₁ hb₁, inter_subset_inter ha₂ hb₂⟩ }
lemma eventually_comap' {f : filter β} {φ : α → β} {p : β → Prop} (hf : ∀ᶠ b in f, p b) :
∀ᶠ a in comap φ f, p (φ a) :=
⟨_, hf, (λ a h, h)⟩
@[simp] lemma eventually_comap {f : filter β} {φ : α → β} {P : α → Prop} :
(∀ᶠ a in comap φ f, P a) ↔ ∀ᶠ b in f, ∀ a, φ a = b → P a :=
begin
split ; intro h,
{ rcases h with ⟨t, t_in, ht⟩,
apply mem_of_superset t_in,
rintro y y_in _ rfl,
apply ht y_in },
{ exact ⟨_, h, λ _ x_in, x_in _ rfl⟩ }
end
@[simp] lemma frequently_comap {f : filter β} {φ : α → β} {P : α → Prop} :
(∃ᶠ a in comap φ f, P a) ↔ ∃ᶠ b in f, ∃ a, φ a = b ∧ P a :=
by simp only [filter.frequently, eventually_comap, not_exists, not_and]
end comap
/-- The monadic bind operation on filter is defined the usual way in terms of `map` and `join`.
Unfortunately, this `bind` does not result in the expected applicative. See `filter.seq` for the
applicative instance. -/
def bind (f : filter α) (m : α → filter β) : filter β := join (map m f)
/-- The applicative sequentiation operation. This is not induced by the bind operation. -/
def seq (f : filter (α → β)) (g : filter α) : filter β :=
⟨{ s | ∃ u ∈ f, ∃ t ∈ g, (∀ m ∈ u, ∀ x ∈ t, (m : α → β) x ∈ s) },
⟨univ, univ_mem, univ, univ_mem,
by simp only [forall_prop_of_true, mem_univ, forall_true_iff]⟩,
λ s₀ s₁ ⟨t₀, t₁, h₀, h₁, h⟩ hst, ⟨t₀, t₁, h₀, h₁, λ x hx y hy, hst $ h _ hx _ hy⟩,
λ s₀ s₁ ⟨t₀, ht₀, t₁, ht₁, ht⟩ ⟨u₀, hu₀, u₁, hu₁, hu⟩,
⟨t₀ ∩ u₀, inter_mem ht₀ hu₀, t₁ ∩ u₁, inter_mem ht₁ hu₁,
λ x ⟨hx₀, hx₁⟩ x ⟨hy₀, hy₁⟩, ⟨ht _ hx₀ _ hy₀, hu _ hx₁ _ hy₁⟩⟩⟩
/-- `pure x` is the set of sets that contain `x`. It is equal to `𝓟 {x}` but
with this definition we have `s ∈ pure a` defeq `a ∈ s`. -/
instance : has_pure filter :=
⟨λ (α : Type u) x,
{ sets := {s | x ∈ s},
inter_sets := λ s t, and.intro,
sets_of_superset := λ s t hs hst, hst hs,
univ_sets := trivial }⟩
instance : has_bind filter := ⟨@filter.bind⟩
instance : has_seq filter := ⟨@filter.seq⟩
instance : functor filter := { map := @filter.map }
lemma pure_sets (a : α) : (pure a : filter α).sets = {s | a ∈ s} := rfl
@[simp] lemma mem_pure {a : α} {s : set α} : s ∈ (pure a : filter α) ↔ a ∈ s := iff.rfl
@[simp] lemma eventually_pure {a : α} {p : α → Prop} :
(∀ᶠ x in pure a, p x) ↔ p a :=
iff.rfl
@[simp] lemma principal_singleton (a : α) : 𝓟 {a} = pure a :=
filter.ext $ λ s, by simp only [mem_pure, mem_principal, singleton_subset_iff]
@[simp] lemma map_pure (f : α → β) (a : α) : map f (pure a) = pure (f a) :=
rfl
@[simp] lemma join_pure (f : filter α) : join (pure f) = f := filter.ext $ λ s, iff.rfl
@[simp] lemma pure_bind (a : α) (m : α → filter β) :
bind (pure a) m = m a :=
by simp only [has_bind.bind, bind, map_pure, join_pure]
section
-- this section needs to be before applicative, otherwise the wrong instance will be chosen
/-- The monad structure on filters. -/
protected def monad : monad filter := { map := @filter.map }
local attribute [instance] filter.monad
protected lemma is_lawful_monad : is_lawful_monad filter :=
{ id_map := λ α f, filter_eq rfl,
pure_bind := λ α β, pure_bind,
bind_assoc := λ α β γ f m₁ m₂, filter_eq rfl,
bind_pure_comp_eq_map := λ α β f x, filter.ext $ λ s,
by simp only [has_bind.bind, bind, functor.map, mem_map', mem_join, mem_set_of_eq,
comp, mem_pure] }
end
instance : applicative filter := { map := @filter.map, seq := @filter.seq }
instance : alternative filter :=
{ failure := λ α, ⊥,
orelse := λ α x y, x ⊔ y }
@[simp] lemma map_def {α β} (m : α → β) (f : filter α) : m <$> f = map m f := rfl
@[simp] lemma bind_def {α β} (f : filter α) (m : α → filter β) : f >>= m = bind f m := rfl
/-! #### `map` and `comap` equations -/
section map
variables {f f₁ f₂ : filter α} {g g₁ g₂ : filter β} {m : α → β} {m' : β → γ} {s : set α} {t : set β}
@[simp] theorem mem_comap : s ∈ comap m g ↔ ∃ t ∈ g, m ⁻¹' t ⊆ s := iff.rfl
theorem preimage_mem_comap (ht : t ∈ g) : m ⁻¹' t ∈ comap m g :=
⟨t, ht, subset.rfl⟩
lemma comap_id : comap id f = f :=
le_antisymm (λ s, preimage_mem_comap) (λ s ⟨t, ht, hst⟩, mem_of_superset ht hst)
lemma comap_const_of_not_mem {x : α} {f : filter α} {V : set α} (hV : V ∈ f) (hx : x ∉ V) :
comap (λ y : α, x) f = ⊥ :=
begin
ext W,
suffices : ∃ t ∈ f, (λ (y : α), x) ⁻¹' t ⊆ W, by simpa,
use [V, hV],
simp [preimage_const_of_not_mem hx],
end
lemma comap_const_of_mem {x : α} {f : filter α} (h : ∀ V ∈ f, x ∈ V) : comap (λ y : α, x) f = ⊤ :=
begin
ext W,
suffices : (∃ (t : set α), t ∈ f ∧ (λ (y : α), x) ⁻¹' t ⊆ W) ↔ W = univ,
by simpa,
split,
{ rintro ⟨V, V_in, hW⟩,
simpa [preimage_const_of_mem (h V V_in), univ_subset_iff] using hW },
{ rintro rfl,
use univ,
simp [univ_mem] },
end
lemma comap_comap {m : γ → β} {n : β → α} : comap m (comap n f) = comap (n ∘ m) f :=
le_antisymm
(λ c ⟨b, hb, (h : preimage (n ∘ m) b ⊆ c)⟩, ⟨preimage n b, preimage_mem_comap hb, h⟩)
(λ c ⟨b, ⟨a, ha, (h₁ : preimage n a ⊆ b)⟩, (h₂ : preimage m b ⊆ c)⟩,
⟨a, ha, show preimage m (preimage n a) ⊆ c, from (preimage_mono h₁).trans h₂⟩)
section comm
variables {δ : Type*}
/-!
The variables in the following lemmas are used as in this diagram:
```
φ
α → β
θ ↓ ↓ ψ
γ → δ
ρ
```
-/
variables {φ : α → β} {θ : α → γ} {ψ : β → δ} {ρ : γ → δ} (H : ψ ∘ φ = ρ ∘ θ)
include H
lemma map_comm (F : filter α) : map ψ (map φ F) = map ρ (map θ F) :=
by rw [filter.map_map, H, ← filter.map_map]
lemma comap_comm (G : filter δ) : comap φ (comap ψ G) = comap θ (comap ρ G) :=
by rw [filter.comap_comap, H, ← filter.comap_comap]
end comm
@[simp] theorem comap_principal {t : set β} : comap m (𝓟 t) = 𝓟 (m ⁻¹' t) :=
filter.ext $ λ s,
⟨λ ⟨u, (hu : t ⊆ u), (b : preimage m u ⊆ s)⟩, (preimage_mono hu).trans b,
λ h, ⟨t, subset.refl t, h⟩⟩
@[simp] theorem comap_pure {b : β} : comap m (pure b) = 𝓟 (m ⁻¹' {b}) :=
by rw [← principal_singleton, comap_principal]
lemma map_le_iff_le_comap : map m f ≤ g ↔ f ≤ comap m g :=
⟨λ h s ⟨t, ht, hts⟩, mem_of_superset (h ht) hts, λ h s ht, h ⟨_, ht, subset.rfl⟩⟩
lemma gc_map_comap (m : α → β) : galois_connection (map m) (comap m) :=
λ f g, map_le_iff_le_comap
@[mono] lemma map_mono : monotone (map m) := (gc_map_comap m).monotone_l
@[mono] lemma comap_mono : monotone (comap m) := (gc_map_comap m).monotone_u
@[simp] lemma map_bot : map m ⊥ = ⊥ := (gc_map_comap m).l_bot
@[simp] lemma map_sup : map m (f₁ ⊔ f₂) = map m f₁ ⊔ map m f₂ := (gc_map_comap m).l_sup
@[simp] lemma map_supr {f : ι → filter α} : map m (⨆ i, f i) = (⨆ i, map m (f i)) :=
(gc_map_comap m).l_supr
@[simp] lemma comap_top : comap m ⊤ = ⊤ := (gc_map_comap m).u_top
@[simp] lemma comap_inf : comap m (g₁ ⊓ g₂) = comap m g₁ ⊓ comap m g₂ := (gc_map_comap m).u_inf
@[simp] lemma comap_infi {f : ι → filter β} : comap m (⨅ i, f i) = (⨅ i, comap m (f i)) :=
(gc_map_comap m).u_infi
lemma le_comap_top (f : α → β) (l : filter α) : l ≤ comap f ⊤ :=
by { rw [comap_top], exact le_top }
lemma map_comap_le : map m (comap m g) ≤ g := (gc_map_comap m).l_u_le _
lemma le_comap_map : f ≤ comap m (map m f) := (gc_map_comap m).le_u_l _
@[simp] lemma comap_bot : comap m ⊥ = ⊥ :=
bot_unique $ λ s _, ⟨∅, by simp only [mem_bot], by simp only [empty_subset, preimage_empty]⟩
lemma disjoint_comap (h : disjoint g₁ g₂) : disjoint (comap m g₁) (comap m g₂) :=
by simp only [disjoint_iff, ← comap_inf, h.eq_bot, comap_bot]
lemma comap_supr {ι} {f : ι → filter β} {m : α → β} :
comap m (supr f) = (⨆ i, comap m (f i)) :=
le_antisymm
(λ s hs,
have ∀ i, ∃ t, t ∈ f i ∧ m ⁻¹' t ⊆ s,
by simpa only [mem_comap, exists_prop, mem_supr] using mem_supr.1 hs,
let ⟨t, ht⟩ := classical.axiom_of_choice this in
⟨⋃ i, t i, mem_supr.2 $ λ i, (f i).sets_of_superset (ht i).1 (subset_Union _ _),
begin
rw [preimage_Union, Union_subset_iff],
exact λ i, (ht i).2
end⟩)
(supr_le $ λ i, comap_mono $ le_supr _ _)
lemma comap_Sup {s : set (filter β)} {m : α → β} : comap m (Sup s) = (⨆ f ∈ s, comap m f) :=
by simp only [Sup_eq_supr, comap_supr, eq_self_iff_true]
lemma comap_sup : comap m (g₁ ⊔ g₂) = comap m g₁ ⊔ comap m g₂ :=
by rw [sup_eq_supr, comap_supr, supr_bool_eq, bool.cond_tt, bool.cond_ff]
lemma map_comap (f : filter β) (m : α → β) : (f.comap m).map m = f ⊓ 𝓟 (range m) :=
begin
refine le_antisymm (le_inf map_comap_le $ le_principal_iff.2 range_mem_map) _,
rintro t' ⟨t, ht, sub⟩,
refine mem_inf_principal.2 (mem_of_superset ht _),
rintro _ hxt ⟨x, rfl⟩,
exact sub hxt
end
lemma map_comap_of_mem {f : filter β} {m : α → β} (hf : range m ∈ f) : (f.comap m).map m = f :=
by rw [map_comap, inf_eq_left.2 (le_principal_iff.2 hf)]
instance [can_lift α β] : can_lift (filter α) (filter β) :=
{ coe := map can_lift.coe,
cond := λ f, ∀ᶠ x : α in f, can_lift.cond β x,
prf := λ f hf, ⟨comap can_lift.coe f, map_comap_of_mem $ hf.mono can_lift.prf⟩ }
lemma comap_le_comap_iff {f g : filter β} {m : α → β} (hf : range m ∈ f) :
comap m f ≤ comap m g ↔ f ≤ g :=
⟨λ h, map_comap_of_mem hf ▸ (map_mono h).trans map_comap_le, λ h, comap_mono h⟩
theorem map_comap_of_surjective {f : α → β} (hf : surjective f) (l : filter β) :
map f (comap f l) = l :=
map_comap_of_mem $ by simp only [hf.range_eq, univ_mem]
lemma _root_.function.surjective.filter_map_top {f : α → β} (hf : surjective f) : map f ⊤ = ⊤ :=
(congr_arg _ comap_top).symm.trans $ map_comap_of_surjective hf ⊤
lemma subtype_coe_map_comap (s : set α) (f : filter α) :
map (coe : s → α) (comap (coe : s → α) f) = f ⊓ 𝓟 s :=
by rw [map_comap, subtype.range_coe]
lemma subtype_coe_map_comap_prod (s : set α) (f : filter (α × α)) :
map (coe : s × s → α × α) (comap (coe : s × s → α × α) f) = f ⊓ 𝓟 (s ×ˢ s) :=
have (coe : s × s → α × α) = (λ x, (x.1, x.2)), by ext ⟨x, y⟩; refl,
by simp [this, map_comap, ← prod_range_range_eq]
lemma image_mem_of_mem_comap {f : filter α} {c : β → α} (h : range c ∈ f) {W : set β}
(W_in : W ∈ comap c f) : c '' W ∈ f :=
begin
rw ← map_comap_of_mem h,
exact image_mem_map W_in
end
lemma image_coe_mem_of_mem_comap {f : filter α} {U : set α} (h : U ∈ f) {W : set U}
(W_in : W ∈ comap (coe : U → α) f) : coe '' W ∈ f :=
image_mem_of_mem_comap (by simp [h]) W_in
lemma comap_map {f : filter α} {m : α → β} (h : injective m) :
comap m (map m f) = f :=
le_antisymm
(λ s hs, mem_of_superset (preimage_mem_comap $ image_mem_map hs) $
by simp only [preimage_image_eq s h])
le_comap_map
lemma mem_comap_iff {f : filter β} {m : α → β} (inj : injective m)
(large : set.range m ∈ f) {S : set α} : S ∈ comap m f ↔ m '' S ∈ f :=
by rw [← image_mem_map_iff inj, map_comap_of_mem large]
lemma le_of_map_le_map_inj' {f g : filter α} {m : α → β} {s : set α}
(hsf : s ∈ f) (hsg : s ∈ g) (hm : ∀ x ∈ s, ∀ y ∈ s, m x = m y → x = y)
(h : map m f ≤ map m g) : f ≤ g :=
λ t ht, by filter_upwards [hsf, h $ image_mem_map (inter_mem hsg ht)]
using λ _ has ⟨_, ⟨hbs, hb⟩, h⟩, hm _ hbs _ has h ▸ hb
lemma le_of_map_le_map_inj_iff {f g : filter α} {m : α → β} {s : set α}
(hsf : s ∈ f) (hsg : s ∈ g) (hm : ∀ x ∈ s, ∀ y ∈ s, m x = m y → x = y) :
map m f ≤ map m g ↔ f ≤ g :=
iff.intro (le_of_map_le_map_inj' hsf hsg hm) (λ h, map_mono h)
lemma eq_of_map_eq_map_inj' {f g : filter α} {m : α → β} {s : set α}
(hsf : s ∈ f) (hsg : s ∈ g) (hm : ∀ x ∈ s, ∀ y ∈ s, m x = m y → x = y)
(h : map m f = map m g) : f = g :=
le_antisymm
(le_of_map_le_map_inj' hsf hsg hm $ le_of_eq h)
(le_of_map_le_map_inj' hsg hsf hm $ le_of_eq h.symm)
lemma map_inj {f g : filter α} {m : α → β} (hm : injective m) (h : map m f = map m g) :
f = g :=
have comap m (map m f) = comap m (map m g), by rw h,
by rwa [comap_map hm, comap_map hm] at this
lemma comap_ne_bot_iff {f : filter β} {m : α → β} : ne_bot (comap m f) ↔ ∀ t ∈ f, ∃ a, m a ∈ t :=
begin
rw ← forall_mem_nonempty_iff_ne_bot,
exact ⟨λ h t t_in, h (m ⁻¹' t) ⟨t, t_in, subset.rfl⟩,
λ h s ⟨u, u_in, hu⟩, let ⟨x, hx⟩ := h u u_in in ⟨x, hu hx⟩⟩,
end
lemma comap_ne_bot {f : filter β} {m : α → β} (hm : ∀ t ∈ f, ∃ a, m a ∈ t) : ne_bot (comap m f) :=
comap_ne_bot_iff.mpr hm
lemma comap_ne_bot_iff_frequently {f : filter β} {m : α → β} :
ne_bot (comap m f) ↔ ∃ᶠ y in f, y ∈ range m :=
by simp [comap_ne_bot_iff, frequently_iff, ← exists_and_distrib_left, and.comm]
lemma comap_ne_bot_iff_compl_range {f : filter β} {m : α → β} :
ne_bot (comap m f) ↔ (range m)ᶜ ∉ f :=
comap_ne_bot_iff_frequently
lemma ne_bot.comap_of_range_mem {f : filter β} {m : α → β}
(hf : ne_bot f) (hm : range m ∈ f) : ne_bot (comap m f) :=
comap_ne_bot_iff_frequently.2 $ eventually.frequently hm
@[simp] lemma comap_fst_ne_bot_iff {f : filter α} :
(f.comap (prod.fst : α × β → α)).ne_bot ↔ f.ne_bot ∧ nonempty β :=
begin
casesI is_empty_or_nonempty β,
{ rw [filter_eq_bot_of_is_empty (f.comap _), ← not_iff_not]; [simp *, apply_instance] },
{ simp [comap_ne_bot_iff_frequently, h] }
end
@[instance] lemma comap_fst_ne_bot [nonempty β] {f : filter α} [ne_bot f] :
(f.comap (prod.fst : α × β → α)).ne_bot :=
comap_fst_ne_bot_iff.2 ⟨‹_›, ‹_›⟩
@[simp] lemma comap_snd_ne_bot_iff {f : filter β} :
(f.comap (prod.snd : α × β → β)).ne_bot ↔ nonempty α ∧ f.ne_bot :=
begin
casesI is_empty_or_nonempty α with hα hα,
{ rw [filter_eq_bot_of_is_empty (f.comap _), ← not_iff_not];
[simpa using hα.elim, apply_instance] },
{ simp [comap_ne_bot_iff_frequently, hα] }
end
@[instance] lemma comap_snd_ne_bot [nonempty α] {f : filter β} [ne_bot f] :
(f.comap (prod.snd : α × β → β)).ne_bot :=
comap_snd_ne_bot_iff.2 ⟨‹_›, ‹_›⟩
lemma comap_eval_ne_bot_iff' {ι : Type*} {α : ι → Type*} {i : ι} {f : filter (α i)} :
(comap (eval i) f).ne_bot ↔ (∀ j, nonempty (α j)) ∧ ne_bot f :=
begin
casesI is_empty_or_nonempty (Π j, α j) with H H,
{ rw [filter_eq_bot_of_is_empty (f.comap _), ← not_iff_not]; [skip, assumption],
simpa [← classical.nonempty_pi] using H.elim },
{ haveI : ∀ j, nonempty (α j), from classical.nonempty_pi.1 H,
simp [comap_ne_bot_iff_frequently, *] }
end
@[simp] lemma comap_eval_ne_bot_iff {ι : Type*} {α : ι → Type*} [∀ j, nonempty (α j)]
{i : ι} {f : filter (α i)} :
(comap (eval i) f).ne_bot ↔ ne_bot f :=
by simp [comap_eval_ne_bot_iff', *]
@[instance] lemma comap_eval_ne_bot {ι : Type*} {α : ι → Type*} [∀ j, nonempty (α j)]
(i : ι) (f : filter (α i)) [ne_bot f] :
(comap (eval i) f).ne_bot :=
comap_eval_ne_bot_iff.2 ‹_›
lemma comap_inf_principal_ne_bot_of_image_mem {f : filter β} {m : α → β}
(hf : ne_bot f) {s : set α} (hs : m '' s ∈ f) :
ne_bot (comap m f ⊓ 𝓟 s) :=
begin
refine ⟨compl_compl s ▸ mt mem_of_eq_bot _⟩,
rintro ⟨t, ht, hts⟩,
rcases hf.nonempty_of_mem (inter_mem hs ht) with ⟨_, ⟨x, hxs, rfl⟩, hxt⟩,
exact absurd hxs (hts hxt)
end
lemma comap_coe_ne_bot_of_le_principal {s : set γ} {l : filter γ} [h : ne_bot l] (h' : l ≤ 𝓟 s) :
ne_bot (comap (coe : s → γ) l) :=
h.comap_of_range_mem $ (@subtype.range_coe γ s).symm ▸ h' (mem_principal_self s)
lemma ne_bot.comap_of_surj {f : filter β} {m : α → β}
(hf : ne_bot f) (hm : surjective m) :
ne_bot (comap m f) :=
hf.comap_of_range_mem $ univ_mem' hm
lemma ne_bot.comap_of_image_mem {f : filter β} {m : α → β} (hf : ne_bot f)
{s : set α} (hs : m '' s ∈ f) :
ne_bot (comap m f) :=
hf.comap_of_range_mem $ mem_of_superset hs (image_subset_range _ _)
@[simp] lemma map_eq_bot_iff : map m f = ⊥ ↔ f = ⊥ :=
⟨by { rw [←empty_mem_iff_bot, ←empty_mem_iff_bot], exact id },
λ h, by simp only [h, map_bot]⟩
lemma map_ne_bot_iff (f : α → β) {F : filter α} : ne_bot (map f F) ↔ ne_bot F :=
by simp only [ne_bot_iff, ne, map_eq_bot_iff]
lemma ne_bot.map (hf : ne_bot f) (m : α → β) : ne_bot (map m f) :=
(map_ne_bot_iff m).2 hf
instance map_ne_bot [hf : ne_bot f] : ne_bot (f.map m) := hf.map m
lemma sInter_comap_sets (f : α → β) (F : filter β) :
⋂₀ (comap f F).sets = ⋂ U ∈ F, f ⁻¹' U :=
begin
ext x,
suffices : (∀ (A : set α) (B : set β), B ∈ F → f ⁻¹' B ⊆ A → x ∈ A) ↔
∀ (B : set β), B ∈ F → f x ∈ B,
by simp only [mem_sInter, mem_Inter, filter.mem_sets, mem_comap, this, and_imp,
exists_prop, mem_preimage, exists_imp_distrib],
split,
{ intros h U U_in,
simpa only [subset.refl, forall_prop_of_true, mem_preimage] using h (f ⁻¹' U) U U_in },
{ intros h V U U_in f_U_V,
exact f_U_V (h U U_in) },
end
end map
-- this is a generic rule for monotone functions:
lemma map_infi_le {f : ι → filter α} {m : α → β} :
map m (infi f) ≤ (⨅ i, map m (f i)) :=
le_infi $ λ i, map_mono $ infi_le _ _
lemma map_infi_eq {f : ι → filter α} {m : α → β} (hf : directed (≥) f) [nonempty ι] :
map m (infi f) = (⨅ i, map m (f i)) :=
map_infi_le.antisymm
(λ s (hs : preimage m s ∈ infi f),
let ⟨i, hi⟩ := (mem_infi_of_directed hf _).1 hs in
have (⨅ i, map m (f i)) ≤ 𝓟 s, from
infi_le_of_le i $ by { simp only [le_principal_iff, mem_map], assumption },
filter.le_principal_iff.1 this)
lemma map_binfi_eq {ι : Type w} {f : ι → filter α} {m : α → β} {p : ι → Prop}
(h : directed_on (f ⁻¹'o (≥)) {x | p x}) (ne : ∃ i, p i) :
map m (⨅ i (h : p i), f i) = (⨅ i (h : p i), map m (f i)) :=
begin
haveI := nonempty_subtype.2 ne,
simp only [infi_subtype'],
exact map_infi_eq h.directed_coe
end
lemma map_inf_le {f g : filter α} {m : α → β} : map m (f ⊓ g) ≤ map m f ⊓ map m g :=
(@map_mono _ _ m).map_inf_le f g
lemma map_inf {f g : filter α} {m : α → β} (h : injective m) :
map m (f ⊓ g) = map m f ⊓ map m g :=
begin
refine map_inf_le.antisymm _,
rintro t ⟨s₁, hs₁, s₂, hs₂, ht : m ⁻¹' t = s₁ ∩ s₂⟩,
refine mem_inf_of_inter (image_mem_map hs₁) (image_mem_map hs₂) _,
rw [image_inter h, image_subset_iff, ht]
end
lemma map_inf' {f g : filter α} {m : α → β} {t : set α} (htf : t ∈ f) (htg : t ∈ g)
(h : inj_on m t) : map m (f ⊓ g) = map m f ⊓ map m g :=
begin
lift f to filter t using htf, lift g to filter t using htg,
replace h : injective (m ∘ coe) := h.injective,
simp only [map_map, ← map_inf subtype.coe_injective, map_inf h],
end
lemma disjoint_map {m : α → β} (hm : injective m) {f₁ f₂ : filter α} :
disjoint (map m f₁) (map m f₂) ↔ disjoint f₁ f₂ :=
by simp only [disjoint_iff, ← map_inf hm, map_eq_bot_iff]
lemma map_eq_comap_of_inverse {f : filter α} {m : α → β} {n : β → α}
(h₁ : m ∘ n = id) (h₂ : n ∘ m = id) : map m f = comap n f :=
le_antisymm
(λ b ⟨a, ha, (h : preimage n a ⊆ b)⟩, f.sets_of_superset ha $
calc a = preimage (n ∘ m) a : by simp only [h₂, preimage_id, eq_self_iff_true]
... ⊆ preimage m b : preimage_mono h)
(λ b (hb : preimage m b ∈ f),
⟨preimage m b, hb, show preimage (m ∘ n) b ⊆ b, by simp only [h₁]; apply subset.refl⟩)
lemma map_swap_eq_comap_swap {f : filter (α × β)} : prod.swap <$> f = comap prod.swap f :=
map_eq_comap_of_inverse prod.swap_swap_eq prod.swap_swap_eq
lemma le_map {f : filter α} {m : α → β} {g : filter β} (h : ∀ s ∈ f, m '' s ∈ g) :
g ≤ f.map m :=
λ s hs, mem_of_superset (h _ hs) $ image_preimage_subset _ _
protected lemma push_pull (f : α → β) (F : filter α) (G : filter β) :
map f (F ⊓ comap f G) = map f F ⊓ G :=
begin
apply le_antisymm,
{ calc map f (F ⊓ comap f G) ≤ map f F ⊓ (map f $ comap f G) : map_inf_le
... ≤ map f F ⊓ G : inf_le_inf_left (map f F) map_comap_le },
{ rintro U ⟨V, V_in, W, ⟨Z, Z_in, hZ⟩, h⟩,
apply mem_inf_of_inter (image_mem_map V_in) Z_in,
calc
f '' V ∩ Z = f '' (V ∩ f ⁻¹' Z) : by rw image_inter_preimage
... ⊆ f '' (V ∩ W) : image_subset _ (inter_subset_inter_right _ ‹_›)
... = f '' (f ⁻¹' U) : by rw h
... ⊆ U : image_preimage_subset f U }
end
protected lemma push_pull' (f : α → β) (F : filter α) (G : filter β) :
map f (comap f G ⊓ F) = G ⊓ map f F :=
by simp only [filter.push_pull, inf_comm]
section applicative
lemma singleton_mem_pure {a : α} : {a} ∈ (pure a : filter α) :=
mem_singleton a
lemma pure_injective : injective (pure : α → filter α) :=
λ a b hab, (filter.ext_iff.1 hab {x | a = x}).1 rfl
instance pure_ne_bot {α : Type u} {a : α} : ne_bot (pure a) :=
⟨mt empty_mem_iff_bot.2 $ not_mem_empty a⟩
@[simp] lemma le_pure_iff {f : filter α} {a : α} : f ≤ pure a ↔ {a} ∈ f :=
⟨λ h, h singleton_mem_pure,
λ h s hs, mem_of_superset h $ singleton_subset_iff.2 hs⟩
lemma mem_seq_def {f : filter (α → β)} {g : filter α} {s : set β} :
s ∈ f.seq g ↔ (∃ u ∈ f, ∃ t ∈ g, ∀ x ∈ u, ∀ y ∈ t, (x : α → β) y ∈ s) :=
iff.rfl
lemma mem_seq_iff {f : filter (α → β)} {g : filter α} {s : set β} :
s ∈ f.seq g ↔ (∃ u ∈ f, ∃ t ∈ g, set.seq u t ⊆ s) :=
by simp only [mem_seq_def, seq_subset, exists_prop, iff_self]
lemma mem_map_seq_iff {f : filter α} {g : filter β} {m : α → β → γ} {s : set γ} :
s ∈ (f.map m).seq g ↔ (∃ t u, t ∈ g ∧ u ∈ f ∧ ∀ x ∈ u, ∀ y ∈ t, m x y ∈ s) :=
iff.intro
(λ ⟨t, ht, s, hs, hts⟩, ⟨s, m ⁻¹' t, hs, ht, λ a, hts _⟩)
(λ ⟨t, s, ht, hs, hts⟩, ⟨m '' s, image_mem_map hs, t, ht, λ f ⟨a, has, eq⟩, eq ▸ hts _ has⟩)
lemma seq_mem_seq {f : filter (α → β)} {g : filter α} {s : set (α → β)} {t : set α}
(hs : s ∈ f) (ht : t ∈ g) : s.seq t ∈ f.seq g :=
⟨s, hs, t, ht, λ f hf a ha, ⟨f, hf, a, ha, rfl⟩⟩
lemma le_seq {f : filter (α → β)} {g : filter α} {h : filter β}
(hh : ∀ t ∈ f, ∀ u ∈ g, set.seq t u ∈ h) : h ≤ seq f g :=
λ s ⟨t, ht, u, hu, hs⟩, mem_of_superset (hh _ ht _ hu) $
λ b ⟨m, hm, a, ha, eq⟩, eq ▸ hs _ hm _ ha
@[mono] lemma seq_mono {f₁ f₂ : filter (α → β)} {g₁ g₂ : filter α}
(hf : f₁ ≤ f₂) (hg : g₁ ≤ g₂) : f₁.seq g₁ ≤ f₂.seq g₂ :=
le_seq $ λ s hs t ht, seq_mem_seq (hf hs) (hg ht)
@[simp] lemma pure_seq_eq_map (g : α → β) (f : filter α) : seq (pure g) f = f.map g :=
begin
refine le_antisymm (le_map $ λ s hs, _) (le_seq $ λ s hs t ht, _),
{ rw ← singleton_seq, apply seq_mem_seq _ hs,
exact singleton_mem_pure },
{ refine sets_of_superset (map g f) (image_mem_map ht) _,
rintro b ⟨a, ha, rfl⟩, exact ⟨g, hs, a, ha, rfl⟩ }
end
@[simp] lemma seq_pure (f : filter (α → β)) (a : α) : seq f (pure a) = map (λ g : α → β, g a) f :=
begin
refine le_antisymm (le_map $ λ s hs, _) (le_seq $ λ s hs t ht, _),
{ rw ← seq_singleton,
exact seq_mem_seq hs singleton_mem_pure },
{ refine sets_of_superset (map (λg:α→β, g a) f) (image_mem_map hs) _,
rintro b ⟨g, hg, rfl⟩, exact ⟨g, hg, a, ht, rfl⟩ }
end
@[simp] lemma seq_assoc (x : filter α) (g : filter (α → β)) (h : filter (β → γ)) :
seq h (seq g x) = seq (seq (map (∘) h) g) x :=
begin
refine le_antisymm (le_seq $ λ s hs t ht, _) (le_seq $ λ s hs t ht, _),
{ rcases mem_seq_iff.1 hs with ⟨u, hu, v, hv, hs⟩,
rcases mem_map_iff_exists_image.1 hu with ⟨w, hw, hu⟩,
refine mem_of_superset _
(set.seq_mono ((set.seq_mono hu subset.rfl).trans hs) subset.rfl),
rw ← set.seq_seq,
exact seq_mem_seq hw (seq_mem_seq hv ht) },
{ rcases mem_seq_iff.1 ht with ⟨u, hu, v, hv, ht⟩,
refine mem_of_superset _ (set.seq_mono subset.rfl ht),
rw set.seq_seq,
exact seq_mem_seq (seq_mem_seq (image_mem_map hs) hu) hv }
end
lemma prod_map_seq_comm (f : filter α) (g : filter β) :
(map prod.mk f).seq g = seq (map (λ b a, (a, b)) g) f :=
begin
refine le_antisymm (le_seq $ λ s hs t ht, _) (le_seq $ λ s hs t ht, _),
{ rcases mem_map_iff_exists_image.1 hs with ⟨u, hu, hs⟩,
refine mem_of_superset _ (set.seq_mono hs subset.rfl),
rw ← set.prod_image_seq_comm,
exact seq_mem_seq (image_mem_map ht) hu },
{ rcases mem_map_iff_exists_image.1 hs with ⟨u, hu, hs⟩,
refine mem_of_superset _ (set.seq_mono hs subset.rfl),
rw set.prod_image_seq_comm,
exact seq_mem_seq (image_mem_map ht) hu }
end
instance : is_lawful_functor (filter : Type u → Type u) :=
{ id_map := λ α f, map_id,
comp_map := λ α β γ f g a, map_map.symm }
instance : is_lawful_applicative (filter : Type u → Type u) :=
{ pure_seq_eq_map := λ α β, pure_seq_eq_map,
map_pure := λ α β, map_pure,
seq_pure := λ α β, seq_pure,
seq_assoc := λ α β γ, seq_assoc }
instance : is_comm_applicative (filter : Type u → Type u) :=
⟨λ α β f g, prod_map_seq_comm f g⟩
lemma {l} seq_eq_filter_seq {α β : Type l} (f : filter (α → β)) (g : filter α) :
f <*> g = seq f g := rfl
end applicative
/-! #### `bind` equations -/
section bind
@[simp] lemma eventually_bind {f : filter α} {m : α → filter β} {p : β → Prop} :
(∀ᶠ y in bind f m, p y) ↔ ∀ᶠ x in f, ∀ᶠ y in m x, p y :=
iff.rfl
@[simp] lemma eventually_eq_bind {f : filter α} {m : α → filter β} {g₁ g₂ : β → γ} :
(g₁ =ᶠ[bind f m] g₂) ↔ ∀ᶠ x in f, g₁ =ᶠ[m x] g₂ :=
iff.rfl
@[simp] lemma eventually_le_bind [has_le γ] {f : filter α} {m : α → filter β} {g₁ g₂ : β → γ} :
(g₁ ≤ᶠ[bind f m] g₂) ↔ ∀ᶠ x in f, g₁ ≤ᶠ[m x] g₂ :=
iff.rfl
lemma mem_bind' {s : set β} {f : filter α} {m : α → filter β} :
s ∈ bind f m ↔ {a | s ∈ m a} ∈ f :=
iff.rfl
@[simp] lemma mem_bind {s : set β} {f : filter α} {m : α → filter β} :
s ∈ bind f m ↔ ∃ t ∈ f, ∀ x ∈ t, s ∈ m x :=
calc s ∈ bind f m ↔ {a | s ∈ m a} ∈ f : iff.rfl
... ↔ (∃ t ∈ f, t ⊆ {a | s ∈ m a}) : exists_mem_subset_iff.symm
... ↔ (∃ t ∈ f, ∀ x ∈ t, s ∈ m x) : iff.rfl
lemma bind_le {f : filter α} {g : α → filter β} {l : filter β} (h : ∀ᶠ x in f, g x ≤ l) :
f.bind g ≤ l :=
join_le $ eventually_map.2 h
@[mono] lemma bind_mono {f₁ f₂ : filter α} {g₁ g₂ : α → filter β} (hf : f₁ ≤ f₂)
(hg : g₁ ≤ᶠ[f₁] g₂) :
bind f₁ g₁ ≤ bind f₂ g₂ :=
begin
refine le_trans (λ s hs, _) (join_mono $ map_mono hf),
simp only [mem_join, mem_bind', mem_map] at hs ⊢,
filter_upwards [hg, hs] with _ hx hs using hx hs,
end
lemma bind_inf_principal {f : filter α} {g : α → filter β} {s : set β} :
f.bind (λ x, g x ⊓ 𝓟 s) = (f.bind g) ⊓ 𝓟 s :=
filter.ext $ λ s, by simp only [mem_bind, mem_inf_principal]
lemma sup_bind {f g : filter α} {h : α → filter β} :
bind (f ⊔ g) h = bind f h ⊔ bind g h :=
by simp only [bind, sup_join, map_sup, eq_self_iff_true]
lemma principal_bind {s : set α} {f : α → filter β} :
(bind (𝓟 s) f) = (⨆ x ∈ s, f x) :=
show join (map f (𝓟 s)) = (⨆ x ∈ s, f x),
by simp only [Sup_image, join_principal_eq_Sup, map_principal, eq_self_iff_true]
end bind
section list_traverse
/- This is a separate section in order to open `list`, but mostly because of universe
equality requirements in `traverse` -/
open list
lemma sequence_mono :
∀ (as bs : list (filter α)), forall₂ (≤) as bs → sequence as ≤ sequence bs
| [] [] forall₂.nil := le_rfl
| (a :: as) (b :: bs) (forall₂.cons h hs) := seq_mono (map_mono h) (sequence_mono as bs hs)
variables {α' β' γ' : Type u} {f : β' → filter α'} {s : γ' → set α'}
lemma mem_traverse :
∀ (fs : list β') (us : list γ'),
forall₂ (λ b c, s c ∈ f b) fs us → traverse s us ∈ traverse f fs
| [] [] forall₂.nil := mem_pure.2 $ mem_singleton _
| (f :: fs) (u :: us) (forall₂.cons h hs) := seq_mem_seq (image_mem_map h) (mem_traverse fs us hs)
lemma mem_traverse_iff (fs : list β') (t : set (list α')) :
t ∈ traverse f fs ↔
(∃ us : list (set α'), forall₂ (λ b (s : set α'), s ∈ f b) fs us ∧ sequence us ⊆ t) :=
begin
split,
{ induction fs generalizing t,
case nil { simp only [sequence, mem_pure, imp_self, forall₂_nil_left_iff,
exists_eq_left, set.pure_def, singleton_subset_iff, traverse_nil] },
case cons : b fs ih t
{ intro ht,
rcases mem_seq_iff.1 ht with ⟨u, hu, v, hv, ht⟩,
rcases mem_map_iff_exists_image.1 hu with ⟨w, hw, hwu⟩,
rcases ih v hv with ⟨us, hus, hu⟩,
exact ⟨w :: us, forall₂.cons hw hus, (set.seq_mono hwu hu).trans ht⟩ } },
{ rintro ⟨us, hus, hs⟩,
exact mem_of_superset (mem_traverse _ _ hus) hs }
end
end list_traverse
/-! ### Limits -/
/-- `tendsto` is the generic "limit of a function" predicate.
`tendsto f l₁ l₂` asserts that for every `l₂` neighborhood `a`,
the `f`-preimage of `a` is an `l₁` neighborhood. -/
def tendsto (f : α → β) (l₁ : filter α) (l₂ : filter β) := l₁.map f ≤ l₂
lemma tendsto_def {f : α → β} {l₁ : filter α} {l₂ : filter β} :
tendsto f l₁ l₂ ↔ ∀ s ∈ l₂, f ⁻¹' s ∈ l₁ := iff.rfl
lemma tendsto_iff_eventually {f : α → β} {l₁ : filter α} {l₂ : filter β} :
tendsto f l₁ l₂ ↔ ∀ ⦃p : β → Prop⦄, (∀ᶠ y in l₂, p y) → ∀ᶠ x in l₁, p (f x) :=
iff.rfl
lemma tendsto.eventually {f : α → β} {l₁ : filter α} {l₂ : filter β} {p : β → Prop}
(hf : tendsto f l₁ l₂) (h : ∀ᶠ y in l₂, p y) :
∀ᶠ x in l₁, p (f x) :=
hf h
lemma tendsto.frequently {f : α → β} {l₁ : filter α} {l₂ : filter β} {p : β → Prop}
(hf : tendsto f l₁ l₂) (h : ∃ᶠ x in l₁, p (f x)) :
∃ᶠ y in l₂, p y :=
mt hf.eventually h
lemma tendsto.frequently_map {l₁ : filter α} {l₂ : filter β} {p : α → Prop} {q : β → Prop}
(f : α → β) (c : filter.tendsto f l₁ l₂) (w : ∀ x, p x → q (f x)) (h : ∃ᶠ x in l₁, p x) :
∃ᶠ y in l₂, q y :=
c.frequently (h.mono w)
@[simp] lemma tendsto_bot {f : α → β} {l : filter β} : tendsto f ⊥ l := by simp [tendsto]
@[simp] lemma tendsto_top {f : α → β} {l : filter α} : tendsto f l ⊤ := le_top
lemma le_map_of_right_inverse {mab : α → β} {mba : β → α} {f : filter α} {g : filter β}
(h₁ : mab ∘ mba =ᶠ[g] id) (h₂ : tendsto mba g f) :
g ≤ map mab f :=
by { rw [← @map_id _ g, ← map_congr h₁, ← map_map], exact map_mono h₂ }
lemma tendsto_of_is_empty [is_empty α] {f : α → β} {la : filter α} {lb : filter β} :
tendsto f la lb :=
by simp only [filter_eq_bot_of_is_empty la, tendsto_bot]
lemma eventually_eq_of_left_inv_of_right_inv {f : α → β} {g₁ g₂ : β → α} {fa : filter α}
{fb : filter β} (hleft : ∀ᶠ x in fa, g₁ (f x) = x) (hright : ∀ᶠ y in fb, f (g₂ y) = y)
(htendsto : tendsto g₂ fb fa) :
g₁ =ᶠ[fb] g₂ :=
(htendsto.eventually hleft).mp $ hright.mono $ λ y hr hl, (congr_arg g₁ hr.symm).trans hl
lemma tendsto_iff_comap {f : α → β} {l₁ : filter α} {l₂ : filter β} :
tendsto f l₁ l₂ ↔ l₁ ≤ l₂.comap f :=
map_le_iff_le_comap
alias tendsto_iff_comap ↔ filter.tendsto.le_comap _
protected lemma tendsto.disjoint {f : α → β} {la₁ la₂ : filter α} {lb₁ lb₂ : filter β}
(h₁ : tendsto f la₁ lb₁) (hd : disjoint lb₁ lb₂) (h₂ : tendsto f la₂ lb₂) :
disjoint la₁ la₂ :=
(disjoint_comap hd).mono h₁.le_comap h₂.le_comap
lemma tendsto_congr' {f₁ f₂ : α → β} {l₁ : filter α} {l₂ : filter β} (hl : f₁ =ᶠ[l₁] f₂) :
tendsto f₁ l₁ l₂ ↔ tendsto f₂ l₁ l₂ :=
by rw [tendsto, tendsto, map_congr hl]
lemma tendsto.congr' {f₁ f₂ : α → β} {l₁ : filter α} {l₂ : filter β}
(hl : f₁ =ᶠ[l₁] f₂) (h : tendsto f₁ l₁ l₂) : tendsto f₂ l₁ l₂ :=
(tendsto_congr' hl).1 h
theorem tendsto_congr {f₁ f₂ : α → β} {l₁ : filter α} {l₂ : filter β}
(h : ∀ x, f₁ x = f₂ x) : tendsto f₁ l₁ l₂ ↔ tendsto f₂ l₁ l₂ :=
tendsto_congr' (univ_mem' h)
theorem tendsto.congr {f₁ f₂ : α → β} {l₁ : filter α} {l₂ : filter β}
(h : ∀ x, f₁ x = f₂ x) : tendsto f₁ l₁ l₂ → tendsto f₂ l₁ l₂ :=
(tendsto_congr h).1
lemma tendsto_id' {x y : filter α} : x ≤ y → tendsto id x y :=
by simp only [tendsto, map_id, forall_true_iff] {contextual := tt}
lemma tendsto_id {x : filter α} : tendsto id x x := tendsto_id' $ le_refl x
lemma tendsto.comp {f : α → β} {g : β → γ} {x : filter α} {y : filter β} {z : filter γ}
(hg : tendsto g y z) (hf : tendsto f x y) : tendsto (g ∘ f) x z :=
calc map (g ∘ f) x = map g (map f x) : by rw [map_map]
... ≤ map g y : map_mono hf
... ≤ z : hg
lemma tendsto.mono_left {f : α → β} {x y : filter α} {z : filter β}
(hx : tendsto f x z) (h : y ≤ x) : tendsto f y z :=
(map_mono h).trans hx
lemma tendsto.mono_right {f : α → β} {x : filter α} {y z : filter β}
(hy : tendsto f x y) (hz : y ≤ z) : tendsto f x z :=
le_trans hy hz
lemma tendsto.ne_bot {f : α → β} {x : filter α} {y : filter β} (h : tendsto f x y) [hx : ne_bot x] :
ne_bot y :=
(hx.map _).mono h
lemma tendsto_map {f : α → β} {x : filter α} : tendsto f x (map f x) := le_refl (map f x)
lemma tendsto_map' {f : β → γ} {g : α → β} {x : filter α} {y : filter γ}
(h : tendsto (f ∘ g) x y) : tendsto f (map g x) y :=
by rwa [tendsto, map_map]
@[simp] lemma tendsto_map'_iff {f : β → γ} {g : α → β} {x : filter α} {y : filter γ} :
tendsto f (map g x) y ↔ tendsto (f ∘ g) x y :=
by { rw [tendsto, map_map], refl }
lemma tendsto_comap {f : α → β} {x : filter β} : tendsto f (comap f x) x :=
map_comap_le
@[simp] lemma tendsto_comap_iff {f : α → β} {g : β → γ} {a : filter α} {c : filter γ} :
tendsto f a (c.comap g) ↔ tendsto (g ∘ f) a c :=
⟨λ h, tendsto_comap.comp h, λ h, map_le_iff_le_comap.mp $ by rwa [map_map]⟩
lemma tendsto_comap'_iff {m : α → β} {f : filter α} {g : filter β} {i : γ → α}
(h : range i ∈ f) : tendsto (m ∘ i) (comap i f) g ↔ tendsto m f g :=
by { rw [tendsto, ← map_compose], simp only [(∘), map_comap_of_mem h, tendsto] }
lemma tendsto.of_tendsto_comp {f : α → β} {g : β → γ} {a : filter α} {b : filter β} {c : filter γ}
(hfg : tendsto (g ∘ f) a c) (hg : comap g c ≤ b) :
tendsto f a b :=
begin
rw tendsto_iff_comap at hfg ⊢,
calc a ≤ comap (g ∘ f) c : hfg
... ≤ comap f b : by simpa [comap_comap] using comap_mono hg
end
lemma comap_eq_of_inverse {f : filter α} {g : filter β} {φ : α → β} (ψ : β → α)
(eq : ψ ∘ φ = id) (hφ : tendsto φ f g) (hψ : tendsto ψ g f) : comap φ g = f :=
begin
refine ((comap_mono $ map_le_iff_le_comap.1 hψ).trans _).antisymm (map_le_iff_le_comap.1 hφ),
rw [comap_comap, eq, comap_id],
exact le_rfl
end
lemma map_eq_of_inverse {f : filter α} {g : filter β} {φ : α → β} (ψ : β → α)
(eq : φ ∘ ψ = id) (hφ : tendsto φ f g) (hψ : tendsto ψ g f) : map φ f = g :=
begin
refine le_antisymm hφ (le_trans _ (map_mono hψ)),
rw [map_map, eq, map_id],
exact le_rfl
end
lemma tendsto_inf {f : α → β} {x : filter α} {y₁ y₂ : filter β} :
tendsto f x (y₁ ⊓ y₂) ↔ tendsto f x y₁ ∧ tendsto f x y₂ :=
by simp only [tendsto, le_inf_iff, iff_self]
lemma tendsto_inf_left {f : α → β} {x₁ x₂ : filter α} {y : filter β}
(h : tendsto f x₁ y) : tendsto f (x₁ ⊓ x₂) y :=
le_trans (map_mono inf_le_left) h
lemma tendsto_inf_right {f : α → β} {x₁ x₂ : filter α} {y : filter β}
(h : tendsto f x₂ y) : tendsto f (x₁ ⊓ x₂) y :=
le_trans (map_mono inf_le_right) h
lemma tendsto.inf {f : α → β} {x₁ x₂ : filter α} {y₁ y₂ : filter β}
(h₁ : tendsto f x₁ y₁) (h₂ : tendsto f x₂ y₂) : tendsto f (x₁ ⊓ x₂) (y₁ ⊓ y₂) :=
tendsto_inf.2 ⟨tendsto_inf_left h₁, tendsto_inf_right h₂⟩
@[simp] lemma tendsto_infi {f : α → β} {x : filter α} {y : ι → filter β} :
tendsto f x (⨅ i, y i) ↔ ∀ i, tendsto f x (y i) :=
by simp only [tendsto, iff_self, le_infi_iff]
lemma tendsto_infi' {f : α → β} {x : ι → filter α} {y : filter β} (i : ι) (hi : tendsto f (x i) y) :
tendsto f (⨅ i, x i) y :=
hi.mono_left $ infi_le _ _
@[simp] lemma tendsto_sup {f : α → β} {x₁ x₂ : filter α} {y : filter β} :
tendsto f (x₁ ⊔ x₂) y ↔ tendsto f x₁ y ∧ tendsto f x₂ y :=
by simp only [tendsto, map_sup, sup_le_iff]
lemma tendsto.sup {f : α → β} {x₁ x₂ : filter α} {y : filter β} :
tendsto f x₁ y → tendsto f x₂ y → tendsto f (x₁ ⊔ x₂) y :=
λ h₁ h₂, tendsto_sup.mpr ⟨ h₁, h₂ ⟩
@[simp] lemma tendsto_supr {f : α → β} {x : ι → filter α} {y : filter β} :
tendsto f (⨆ i, x i) y ↔ ∀ i, tendsto f (x i) y :=
by simp only [tendsto, map_supr, supr_le_iff]
@[simp] lemma tendsto_principal {f : α → β} {l : filter α} {s : set β} :
tendsto f l (𝓟 s) ↔ ∀ᶠ a in l, f a ∈ s :=
by simp only [tendsto, le_principal_iff, mem_map', filter.eventually]
@[simp] lemma tendsto_principal_principal {f : α → β} {s : set α} {t : set β} :
tendsto f (𝓟 s) (𝓟 t) ↔ ∀ a ∈ s, f a ∈ t :=
by simp only [tendsto_principal, eventually_principal]
@[simp] lemma tendsto_pure {f : α → β} {a : filter α} {b : β} :
tendsto f a (pure b) ↔ ∀ᶠ x in a, f x = b :=
by simp only [tendsto, le_pure_iff, mem_map', mem_singleton_iff, filter.eventually]
lemma tendsto_pure_pure (f : α → β) (a : α) :
tendsto f (pure a) (pure (f a)) :=
tendsto_pure.2 rfl
lemma tendsto_const_pure {a : filter α} {b : β} : tendsto (λ x, b) a (pure b) :=
tendsto_pure.2 $ univ_mem' $ λ _, rfl
lemma pure_le_iff {a : α} {l : filter α} : pure a ≤ l ↔ ∀ s ∈ l, a ∈ s :=
iff.rfl
lemma tendsto_pure_left {f : α → β} {a : α} {l : filter β} :
tendsto f (pure a) l ↔ ∀ s ∈ l, f a ∈ s :=
iff.rfl
@[simp] lemma map_inf_principal_preimage {f : α → β} {s : set β} {l : filter α} :
map f (l ⊓ 𝓟 (f ⁻¹' s)) = map f l ⊓ 𝓟 s :=
filter.ext $ λ t, by simp only [mem_map', mem_inf_principal, mem_set_of_eq, mem_preimage]
/-- If two filters are disjoint, then a function cannot tend to both of them along a non-trivial
filter. -/
lemma tendsto.not_tendsto {f : α → β} {a : filter α} {b₁ b₂ : filter β} (hf : tendsto f a b₁)
[ne_bot a] (hb : disjoint b₁ b₂) :
¬ tendsto f a b₂ :=
λ hf', (tendsto_inf.2 ⟨hf, hf'⟩).ne_bot.ne hb.eq_bot
lemma tendsto.if {l₁ : filter α} {l₂ : filter β} {f g : α → β} {p : α → Prop} [∀ x, decidable (p x)]
(h₀ : tendsto f (l₁ ⊓ 𝓟 {x | p x}) l₂) (h₁ : tendsto g (l₁ ⊓ 𝓟 { x | ¬ p x }) l₂) :
tendsto (λ x, if p x then f x else g x) l₁ l₂ :=
begin
simp only [tendsto_def, mem_inf_principal] at *,
intros s hs,
filter_upwards [h₀ s hs, h₁ s hs],
simp only [mem_preimage],
intros x hp₀ hp₁,
split_ifs,
exacts [hp₀ h, hp₁ h],
end
lemma tendsto.piecewise {l₁ : filter α} {l₂ : filter β} {f g : α → β}
{s : set α} [∀ x, decidable (x ∈ s)]
(h₀ : tendsto f (l₁ ⊓ 𝓟 s) l₂) (h₁ : tendsto g (l₁ ⊓ 𝓟 sᶜ) l₂) :
tendsto (piecewise s f g) l₁ l₂ :=
h₀.if h₁
/-! ### Products of filters -/
section prod
variables {s : set α} {t : set β} {f : filter α} {g : filter β}
/- The product filter cannot be defined using the monad structure on filters. For example:
F := do {x ← seq, y ← top, return (x, y)}
hence:
s ∈ F ↔ ∃ n, [n..∞] × univ ⊆ s
G := do {y ← top, x ← seq, return (x, y)}
hence:
s ∈ G ↔ ∀ i:ℕ, ∃ n, [n..∞] × {i} ⊆ s
Now ⋃ i, [i..∞] × {i} is in G but not in F.
As product filter we want to have F as result.
-/
/-- Product of filters. This is the filter generated by cartesian products
of elements of the component filters. -/
protected def prod (f : filter α) (g : filter β) : filter (α × β) :=
f.comap prod.fst ⊓ g.comap prod.snd
localized "infix ` ×ᶠ `:60 := filter.prod" in filter
lemma prod_mem_prod {s : set α} {t : set β} {f : filter α} {g : filter β}
(hs : s ∈ f) (ht : t ∈ g) : s ×ˢ t ∈ f ×ᶠ g :=
inter_mem_inf (preimage_mem_comap hs) (preimage_mem_comap ht)
lemma mem_prod_iff {s : set (α×β)} {f : filter α} {g : filter β} :
s ∈ f ×ᶠ g ↔ (∃ t₁ ∈ f, ∃ t₂ ∈ g, t₁ ×ˢ t₂ ⊆ s) :=
begin
simp only [filter.prod],
split,
{ rintro ⟨t₁, ⟨s₁, hs₁, hts₁⟩, t₂, ⟨s₂, hs₂, hts₂⟩, rfl⟩,
exact ⟨s₁, hs₁, s₂, hs₂, λ p ⟨h, h'⟩, ⟨hts₁ h, hts₂ h'⟩⟩ },
{ rintro ⟨t₁, ht₁, t₂, ht₂, h⟩,
exact mem_inf_of_inter (preimage_mem_comap ht₁) (preimage_mem_comap ht₂) h }
end
@[simp] lemma prod_mem_prod_iff {s : set α} {t : set β} {f : filter α} {g : filter β}
[f.ne_bot] [g.ne_bot] :
s ×ˢ t ∈ f ×ᶠ g ↔ s ∈ f ∧ t ∈ g :=
⟨λ h, let ⟨s', hs', t', ht', H⟩ := mem_prod_iff.1 h in (prod_subset_prod_iff.1 H).elim
(λ ⟨hs's, ht't⟩, ⟨mem_of_superset hs' hs's, mem_of_superset ht' ht't⟩)
(λ h, h.elim
(λ hs'e, absurd hs'e (nonempty_of_mem hs').ne_empty)
(λ ht'e, absurd ht'e (nonempty_of_mem ht').ne_empty)),
λ h, prod_mem_prod h.1 h.2⟩
lemma mem_prod_principal {f : filter α} {s : set (α × β)} {t : set β}:
s ∈ f ×ᶠ 𝓟 t ↔ {a | ∀ b ∈ t, (a, b) ∈ s} ∈ f :=
begin
rw [← @exists_mem_subset_iff _ f, mem_prod_iff],
refine exists₂_congr (λ u u_in, ⟨_, λ h, ⟨t, mem_principal_self t, _⟩⟩),
{ rintros ⟨v, v_in, hv⟩ a a_in b b_in,
exact hv (mk_mem_prod a_in $ v_in b_in) },
{ rintro ⟨x, y⟩ ⟨hx, hy⟩,
exact h hx y hy }
end
lemma mem_prod_top {f : filter α} {s : set (α × β)} :
s ∈ f ×ᶠ (⊤ : filter β) ↔ {a | ∀ b, (a, b) ∈ s} ∈ f :=
begin
rw [← principal_univ, mem_prod_principal],
simp only [mem_univ, forall_true_left]
end
lemma comap_prod (f : α → β × γ) (b : filter β) (c : filter γ) :
comap f (b ×ᶠ c) = (comap (prod.fst ∘ f) b) ⊓ (comap (prod.snd ∘ f) c) :=
by erw [comap_inf, filter.comap_comap, filter.comap_comap]
lemma prod_top {f : filter α} : f ×ᶠ (⊤ : filter β) = f.comap prod.fst :=
by rw [filter.prod, comap_top, inf_top_eq]
lemma sup_prod (f₁ f₂ : filter α) (g : filter β) : (f₁ ⊔ f₂) ×ᶠ g = (f₁ ×ᶠ g) ⊔ (f₂ ×ᶠ g) :=
by rw [filter.prod, comap_sup, inf_sup_right, ← filter.prod, ← filter.prod]
lemma prod_sup (f : filter α) (g₁ g₂ : filter β) : f ×ᶠ (g₁ ⊔ g₂) = (f ×ᶠ g₁) ⊔ (f ×ᶠ g₂) :=
by rw [filter.prod, comap_sup, inf_sup_left, ← filter.prod, ← filter.prod]
lemma eventually_prod_iff {p : α × β → Prop} {f : filter α} {g : filter β} :
(∀ᶠ x in f ×ᶠ g, p x) ↔ ∃ (pa : α → Prop) (ha : ∀ᶠ x in f, pa x)
(pb : β → Prop) (hb : ∀ᶠ y in g, pb y), ∀ {x}, pa x → ∀ {y}, pb y → p (x, y) :=
by simpa only [set.prod_subset_iff] using @mem_prod_iff α β p f g
lemma tendsto_fst {f : filter α} {g : filter β} : tendsto prod.fst (f ×ᶠ g) f :=
tendsto_inf_left tendsto_comap
lemma tendsto_snd {f : filter α} {g : filter β} : tendsto prod.snd (f ×ᶠ g) g :=
tendsto_inf_right tendsto_comap
lemma tendsto.prod_mk {f : filter α} {g : filter β} {h : filter γ} {m₁ : α → β} {m₂ : α → γ}
(h₁ : tendsto m₁ f g) (h₂ : tendsto m₂ f h) : tendsto (λ x, (m₁ x, m₂ x)) f (g ×ᶠ h) :=
tendsto_inf.2 ⟨tendsto_comap_iff.2 h₁, tendsto_comap_iff.2 h₂⟩
lemma eventually.prod_inl {la : filter α} {p : α → Prop} (h : ∀ᶠ x in la, p x) (lb : filter β) :
∀ᶠ x in la ×ᶠ lb, p (x : α × β).1 :=
tendsto_fst.eventually h
lemma eventually.prod_inr {lb : filter β} {p : β → Prop} (h : ∀ᶠ x in lb, p x) (la : filter α) :
∀ᶠ x in la ×ᶠ lb, p (x : α × β).2 :=
tendsto_snd.eventually h
lemma eventually.prod_mk {la : filter α} {pa : α → Prop} (ha : ∀ᶠ x in la, pa x)
{lb : filter β} {pb : β → Prop} (hb : ∀ᶠ y in lb, pb y) :
∀ᶠ p in la ×ᶠ lb, pa (p : α × β).1 ∧ pb p.2 :=
(ha.prod_inl lb).and (hb.prod_inr la)
lemma eventually.curry {la : filter α} {lb : filter β} {p : α × β → Prop}
(h : ∀ᶠ x in la ×ᶠ lb, p x) :
∀ᶠ x in la, ∀ᶠ y in lb, p (x, y) :=
begin
rcases eventually_prod_iff.1 h with ⟨pa, ha, pb, hb, h⟩,
exact ha.mono (λ a ha, hb.mono $ λ b hb, h ha hb)
end
lemma prod_infi_left [nonempty ι] {f : ι → filter α} {g : filter β}:
(⨅ i, f i) ×ᶠ g = (⨅ i, (f i) ×ᶠ g) :=
by { rw [filter.prod, comap_infi, infi_inf], simp only [filter.prod, eq_self_iff_true] }
lemma prod_infi_right [nonempty ι] {f : filter α} {g : ι → filter β} :
f ×ᶠ (⨅ i, g i) = (⨅ i, f ×ᶠ (g i)) :=
by { rw [filter.prod, comap_infi, inf_infi], simp only [filter.prod, eq_self_iff_true] }
@[mono] lemma prod_mono {f₁ f₂ : filter α} {g₁ g₂ : filter β} (hf : f₁ ≤ f₂) (hg : g₁ ≤ g₂) :
f₁ ×ᶠ g₁ ≤ f₂ ×ᶠ g₂ :=
inf_le_inf (comap_mono hf) (comap_mono hg)
lemma prod_comap_comap_eq {α₁ : Type u} {α₂ : Type v} {β₁ : Type w} {β₂ : Type x}
{f₁ : filter α₁} {f₂ : filter α₂} {m₁ : β₁ → α₁} {m₂ : β₂ → α₂} :
(comap m₁ f₁) ×ᶠ (comap m₂ f₂) = comap (λ p : β₁×β₂, (m₁ p.1, m₂ p.2)) (f₁ ×ᶠ f₂) :=
by simp only [filter.prod, comap_comap, eq_self_iff_true, comap_inf]
lemma prod_comm' : f ×ᶠ g = comap (prod.swap) (g ×ᶠ f) :=
by simp only [filter.prod, comap_comap, (∘), inf_comm, prod.fst_swap,
eq_self_iff_true, prod.snd_swap, comap_inf]
lemma prod_comm : f ×ᶠ g = map (λ p : β×α, (p.2, p.1)) (g ×ᶠ f) :=
by { rw [prod_comm', ← map_swap_eq_comap_swap], refl }
lemma prod_map_map_eq {α₁ : Type u} {α₂ : Type v} {β₁ : Type w} {β₂ : Type x}
{f₁ : filter α₁} {f₂ : filter α₂} {m₁ : α₁ → β₁} {m₂ : α₂ → β₂} :
(map m₁ f₁) ×ᶠ (map m₂ f₂) = map (λ p : α₁×α₂, (m₁ p.1, m₂ p.2)) (f₁ ×ᶠ f₂) :=
le_antisymm
(λ s hs,
let ⟨s₁, hs₁, s₂, hs₂, h⟩ := mem_prod_iff.mp hs in
filter.sets_of_superset _ (prod_mem_prod (image_mem_map hs₁) (image_mem_map hs₂)) $
calc m₁ '' s₁ ×ˢ m₂ '' s₂ = (λ p : α₁×α₂, (m₁ p.1, m₂ p.2)) '' (s₁ ×ˢ s₂) :
set.prod_image_image_eq
... ⊆ _ : by rwa [image_subset_iff])
((tendsto.comp le_rfl tendsto_fst).prod_mk (tendsto.comp le_rfl tendsto_snd))
lemma prod_map_map_eq' {α₁ : Type*} {α₂ : Type*} {β₁ : Type*} {β₂ : Type*}
(f : α₁ → α₂) (g : β₁ → β₂) (F : filter α₁) (G : filter β₁) :
(map f F) ×ᶠ (map g G) = map (prod.map f g) (F ×ᶠ G) :=
prod_map_map_eq
lemma tendsto.prod_map {δ : Type*} {f : α → γ} {g : β → δ} {a : filter α} {b : filter β}
{c : filter γ} {d : filter δ} (hf : tendsto f a c) (hg : tendsto g b d) :
tendsto (prod.map f g) (a ×ᶠ b) (c ×ᶠ d) :=
begin
erw [tendsto, ← prod_map_map_eq],
exact filter.prod_mono hf hg,
end
lemma map_prod (m : α × β → γ) (f : filter α) (g : filter β) :
map m (f ×ᶠ g) = (f.map (λ a b, m (a, b))).seq g :=
begin
simp [filter.ext_iff, mem_prod_iff, mem_map_seq_iff],
intro s,
split,
exact λ ⟨t, ht, s, hs, h⟩, ⟨s, hs, t, ht, λ x hx y hy, @h ⟨x, y⟩ ⟨hx, hy⟩⟩,
exact λ ⟨s, hs, t, ht, h⟩, ⟨t, ht, s, hs, λ ⟨x, y⟩ ⟨hx, hy⟩, h x hx y hy⟩
end
lemma prod_eq {f : filter α} {g : filter β} : f ×ᶠ g = (f.map prod.mk).seq g :=
have h : _ := map_prod id f g, by rwa [map_id] at h
lemma prod_inf_prod {f₁ f₂ : filter α} {g₁ g₂ : filter β} :
(f₁ ×ᶠ g₁) ⊓ (f₂ ×ᶠ g₂) = (f₁ ⊓ f₂) ×ᶠ (g₁ ⊓ g₂) :=
by simp only [filter.prod, comap_inf, inf_comm, inf_assoc, inf_left_comm]
@[simp] lemma prod_bot {f : filter α} : f ×ᶠ (⊥ : filter β) = ⊥ := by simp [filter.prod]
@[simp] lemma bot_prod {g : filter β} : (⊥ : filter α) ×ᶠ g = ⊥ := by simp [filter.prod]
@[simp] lemma prod_principal_principal {s : set α} {t : set β} :
(𝓟 s) ×ᶠ (𝓟 t) = 𝓟 (s ×ˢ t) :=
by simp only [filter.prod, comap_principal, principal_eq_iff_eq, comap_principal, inf_principal];
refl
@[simp] lemma pure_prod {a : α} {f : filter β} : pure a ×ᶠ f = map (prod.mk a) f :=
by rw [prod_eq, map_pure, pure_seq_eq_map]
@[simp] lemma prod_pure {f : filter α} {b : β} : f ×ᶠ pure b = map (λ a, (a, b)) f :=
by rw [prod_eq, seq_pure, map_map]
lemma prod_pure_pure {a : α} {b : β} : (pure a) ×ᶠ (pure b) = pure (a, b) :=
by simp
lemma prod_eq_bot {f : filter α} {g : filter β} : f ×ᶠ g = ⊥ ↔ (f = ⊥ ∨ g = ⊥) :=
begin
split,
{ intro h,
rcases mem_prod_iff.1 (empty_mem_iff_bot.2 h) with ⟨s, hs, t, ht, hst⟩,
rw [subset_empty_iff, set.prod_eq_empty_iff] at hst,
cases hst with s_eq t_eq,
{ left, exact empty_mem_iff_bot.1 (s_eq ▸ hs) },
{ right, exact empty_mem_iff_bot.1 (t_eq ▸ ht) } },
{ rintro (rfl | rfl),
exact bot_prod,
exact prod_bot }
end
lemma prod_ne_bot {f : filter α} {g : filter β} : ne_bot (f ×ᶠ g) ↔ (ne_bot f ∧ ne_bot g) :=
by simp only [ne_bot_iff, ne, prod_eq_bot, not_or_distrib]
lemma ne_bot.prod {f : filter α} {g : filter β} (hf : ne_bot f) (hg : ne_bot g) :
ne_bot (f ×ᶠ g) :=
prod_ne_bot.2 ⟨hf, hg⟩
instance prod_ne_bot' {f : filter α} {g : filter β} [hf : ne_bot f] [hg : ne_bot g] :
ne_bot (f ×ᶠ g) :=
hf.prod hg
lemma tendsto_prod_iff {f : α × β → γ} {x : filter α} {y : filter β} {z : filter γ} :
filter.tendsto f (x ×ᶠ y) z ↔
∀ W ∈ z, ∃ U ∈ x, ∃ V ∈ y, ∀ x y, x ∈ U → y ∈ V → f (x, y) ∈ W :=
by simp only [tendsto_def, mem_prod_iff, prod_sub_preimage_iff, exists_prop, iff_self]
end prod
/-! ### Coproducts of filters -/
section coprod
variables {f : filter α} {g : filter β}
/-- Coproduct of filters. -/
protected def coprod (f : filter α) (g : filter β) : filter (α × β) :=
f.comap prod.fst ⊔ g.comap prod.snd
lemma mem_coprod_iff {s : set (α×β)} {f : filter α} {g : filter β} :
s ∈ f.coprod g ↔ ((∃ t₁ ∈ f, prod.fst ⁻¹' t₁ ⊆ s) ∧ (∃ t₂ ∈ g, prod.snd ⁻¹' t₂ ⊆ s)) :=
by simp [filter.coprod]
@[mono] lemma coprod_mono {f₁ f₂ : filter α} {g₁ g₂ : filter β} (hf : f₁ ≤ f₂) (hg : g₁ ≤ g₂) :
f₁.coprod g₁ ≤ f₂.coprod g₂ :=
sup_le_sup (comap_mono hf) (comap_mono hg)
lemma coprod_ne_bot_iff : (f.coprod g).ne_bot ↔ f.ne_bot ∧ nonempty β ∨ nonempty α ∧ g.ne_bot :=
by simp [filter.coprod]
@[instance] lemma coprod_ne_bot_left [ne_bot f] [nonempty β] : (f.coprod g).ne_bot :=
coprod_ne_bot_iff.2 (or.inl ⟨‹_›, ‹_›⟩)
@[instance] lemma coprod_ne_bot_right [ne_bot g] [nonempty α] : (f.coprod g).ne_bot :=
coprod_ne_bot_iff.2 (or.inr ⟨‹_›, ‹_›⟩)
lemma principal_coprod_principal (s : set α) (t : set β) :
(𝓟 s).coprod (𝓟 t) = 𝓟 (sᶜ ×ˢ tᶜ)ᶜ :=
begin
rw [filter.coprod, comap_principal, comap_principal, sup_principal],
congr,
ext x,
simp ; tauto,
end
-- this inequality can be strict; see `map_const_principal_coprod_map_id_principal` and
-- `map_prod_map_const_id_principal_coprod_principal` below.
lemma map_prod_map_coprod_le {α₁ : Type u} {α₂ : Type v} {β₁ : Type w} {β₂ : Type x}
{f₁ : filter α₁} {f₂ : filter α₂} {m₁ : α₁ → β₁} {m₂ : α₂ → β₂} :
map (prod.map m₁ m₂) (f₁.coprod f₂) ≤ (map m₁ f₁).coprod (map m₂ f₂) :=
begin
intros s,
simp only [mem_map, mem_coprod_iff],
rintro ⟨⟨u₁, hu₁, h₁⟩, u₂, hu₂, h₂⟩,
refine ⟨⟨m₁ ⁻¹' u₁, hu₁, λ _ hx, h₁ _⟩, ⟨m₂ ⁻¹' u₂, hu₂, λ _ hx, h₂ _⟩⟩; convert hx
end
/-- Characterization of the coproduct of the `filter.map`s of two principal filters `𝓟 {a}` and
`𝓟 {i}`, the first under the constant function `λ a, b` and the second under the identity function.
Together with the next lemma, `map_prod_map_const_id_principal_coprod_principal`, this provides an
example showing that the inequality in the lemma `map_prod_map_coprod_le` can be strict. -/
lemma map_const_principal_coprod_map_id_principal {α β ι : Type*} (a : α) (b : β) (i : ι) :
(map (λ _ : α, b) (𝓟 {a})).coprod (map id (𝓟 {i}))
= 𝓟 (({b} : set β) ×ˢ (univ : set ι) ∪ (univ : set β) ×ˢ ({i} : set ι)) :=
begin
rw [map_principal, map_principal, principal_coprod_principal],
congr,
ext ⟨b', i'⟩,
simp,
tauto,
end
/-- Characterization of the `filter.map` of the coproduct of two principal filters `𝓟 {a}` and
`𝓟 {i}`, under the `prod.map` of two functions, respectively the constant function `λ a, b` and the
identity function. Together with the previous lemma,
`map_const_principal_coprod_map_id_principal`, this provides an example showing that the inequality
in the lemma `map_prod_map_coprod_le` can be strict. -/
lemma map_prod_map_const_id_principal_coprod_principal {α β ι : Type*} (a : α) (b : β) (i : ι) :
map (prod.map (λ _ : α, b) id) ((𝓟 {a}).coprod (𝓟 {i}))
= 𝓟 (({b} : set β) ×ˢ (univ : set ι)) :=
begin
rw [principal_coprod_principal, map_principal],
congr,
ext ⟨b', i'⟩,
split,
{ rintro ⟨⟨a'', i''⟩, h₁, h₂, h₃⟩,
simp },
{ rintro ⟨h₁, h₂⟩,
use (a, i'),
simpa using h₁.symm }
end
lemma tendsto.prod_map_coprod {δ : Type*} {f : α → γ} {g : β → δ} {a : filter α} {b : filter β}
{c : filter γ} {d : filter δ} (hf : tendsto f a c) (hg : tendsto g b d) :
tendsto (prod.map f g) (a.coprod b) (c.coprod d) :=
map_prod_map_coprod_le.trans (coprod_mono hf hg)
end coprod
end filter
open_locale filter
lemma set.eq_on.eventually_eq {α β} {s : set α} {f g : α → β} (h : eq_on f g s) :
f =ᶠ[𝓟 s] g :=
h
lemma set.eq_on.eventually_eq_of_mem {α β} {s : set α} {l : filter α} {f g : α → β}
(h : eq_on f g s) (hl : s ∈ l) :
f =ᶠ[l] g :=
h.eventually_eq.filter_mono $ filter.le_principal_iff.2 hl
lemma set.subset.eventually_le {α} {l : filter α} {s t : set α} (h : s ⊆ t) : s ≤ᶠ[l] t :=
filter.eventually_of_forall h
lemma set.maps_to.tendsto {α β} {s : set α} {t : set β} {f : α → β} (h : maps_to f s t) :
filter.tendsto f (𝓟 s) (𝓟 t) :=
filter.tendsto_principal_principal.2 h
|
c0ffa2c44b3f84b292f19ab2767ebea6476110d8 | 5ae26df177f810c5006841e9c73dc56e01b978d7 | /src/topology/uniform_space/separation.lean | b1b65c00ed2a8b9040a953f0b5adb2d36bb3ef28 | [
"Apache-2.0"
] | permissive | ChrisHughes24/mathlib | 98322577c460bc6b1fe5c21f42ce33ad1c3e5558 | a2a867e827c2a6702beb9efc2b9282bd801d5f9a | refs/heads/master | 1,583,848,251,477 | 1,565,164,247,000 | 1,565,164,247,000 | 129,409,993 | 0 | 1 | Apache-2.0 | 1,565,164,817,000 | 1,523,628,059,000 | Lean | UTF-8 | Lean | false | false | 13,603 | lean | /-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Patrick Massot
Hausdorff properties of uniform spaces. Separation quotient.
-/
import topology.uniform_space.basic
open filter topological_space lattice set classical
local attribute [instance, priority 0] prop_decidable
noncomputable theory
set_option eqn_compiler.zeta true
universes u v w
variables {α : Type u} {β : Type v} {γ : Type w}
variables [uniform_space α] [uniform_space β] [uniform_space γ]
local notation `𝓤` := uniformity
/- separated uniformity -/
/-- The separation relation is the intersection of all entourages.
Two points which are related by the separation relation are "indistinguishable"
according to the uniform structure. -/
protected def separation_rel (α : Type u) [u : uniform_space α] :=
⋂₀ (𝓤 α).sets
lemma separated_equiv : equivalence (λx y, (x, y) ∈ separation_rel α) :=
⟨assume x, assume s, refl_mem_uniformity,
assume x y, assume h (s : set (α×α)) hs,
have preimage prod.swap s ∈ 𝓤 α,
from symm_le_uniformity hs,
h _ this,
assume x y z (hxy : (x, y) ∈ separation_rel α) (hyz : (y, z) ∈ separation_rel α)
s (hs : s ∈ 𝓤 α),
let ⟨t, ht, (h_ts : comp_rel t t ⊆ s)⟩ := comp_mem_uniformity_sets hs in
h_ts $ show (x, z) ∈ comp_rel t t,
from ⟨y, hxy t ht, hyz t ht⟩⟩
@[class] def separated (α : Type u) [uniform_space α] :=
separation_rel α = id_rel
theorem separated_def {α : Type u} [uniform_space α] :
separated α ↔ ∀ x y, (∀ r ∈ 𝓤 α, (x, y) ∈ r) → x = y :=
by simp [separated, id_rel_subset.2 separated_equiv.1, subset.antisymm_iff];
simp [subset_def, separation_rel]
theorem separated_def' {α : Type u} [uniform_space α] :
separated α ↔ ∀ x y, x ≠ y → ∃ r ∈ 𝓤 α, (x, y) ∉ r :=
separated_def.trans $ forall_congr $ λ x, forall_congr $ λ y,
by rw ← not_imp_not; simp [classical.not_forall]
instance separated_t2 [s : separated α] : t2_space α :=
⟨assume x y, assume h : x ≠ y,
let ⟨d, hd, (hxy : (x, y) ∉ d)⟩ := separated_def'.1 s x y h in
let ⟨d', hd', (hd'd' : comp_rel d' d' ⊆ d)⟩ := comp_mem_uniformity_sets hd in
have {y | (x, y) ∈ d'} ∈ nhds x,
from mem_nhds_left x hd',
let ⟨u, hu₁, hu₂, hu₃⟩ := mem_nhds_sets_iff.mp this in
have {x | (x, y) ∈ d'} ∈ nhds y,
from mem_nhds_right y hd',
let ⟨v, hv₁, hv₂, hv₃⟩ := mem_nhds_sets_iff.mp this in
have u ∩ v = ∅, from
eq_empty_of_subset_empty $
assume z ⟨(h₁ : z ∈ u), (h₂ : z ∈ v)⟩,
have (x, y) ∈ comp_rel d' d', from ⟨z, hu₁ h₁, hv₁ h₂⟩,
hxy $ hd'd' this,
⟨u, v, hu₂, hv₂, hu₃, hv₃, this⟩⟩
instance separated_regular [separated α] : regular_space α :=
{ regular := λs a hs ha,
have -s ∈ nhds a,
from mem_nhds_sets hs ha,
have {p : α × α | p.1 = a → p.2 ∈ -s} ∈ 𝓤 α,
from mem_nhds_uniformity_iff.mp this,
let ⟨d, hd, h⟩ := comp_mem_uniformity_sets this in
let e := {y:α| (a, y) ∈ d} in
have hae : a ∈ closure e, from subset_closure $ refl_mem_uniformity hd,
have set.prod (closure e) (closure e) ⊆ comp_rel d (comp_rel (set.prod e e) d),
begin
rw [←closure_prod_eq, closure_eq_inter_uniformity],
change (⨅d' ∈ 𝓤 α, _) ≤ comp_rel d (comp_rel _ d),
exact (infi_le_of_le d $ infi_le_of_le hd $ le_refl _)
end,
have e_subset : closure e ⊆ -s,
from assume a' ha',
let ⟨x, (hx : (a, x) ∈ d), y, ⟨hx₁, hx₂⟩, (hy : (y, _) ∈ d)⟩ := @this ⟨a, a'⟩ ⟨hae, ha'⟩ in
have (a, a') ∈ comp_rel d d, from ⟨y, hx₂, hy⟩,
h this rfl,
have closure e ∈ nhds a, from (nhds a).sets_of_superset (mem_nhds_left a hd) subset_closure,
have nhds a ⊓ principal (-closure e) = ⊥,
from (@inf_eq_bot_iff_le_compl _ _ _ (principal (- closure e)) (principal (closure e))
(by simp [principal_univ, union_comm]) (by simp)).mpr (by simp [this]),
⟨- closure e, is_closed_closure, assume x h₁ h₂, @e_subset x h₂ h₁, this⟩,
..separated_t2 }
/- separation space -/
namespace uniform_space
def separation_setoid (α : Type u) [uniform_space α] : setoid α :=
⟨λx y, (x, y) ∈ separation_rel α, separated_equiv⟩
local attribute [instance] separation_setoid
instance {α : Type u} [u : uniform_space α] : uniform_space (quotient (separation_setoid α)) :=
{ to_topological_space := u.to_topological_space.coinduced (λx, ⟦x⟧),
uniformity := map (λp:(α×α), (⟦p.1⟧, ⟦p.2⟧)) u.uniformity,
refl := le_trans (by simp [quotient.exists_rep]) (filter.map_mono refl_le_uniformity),
symm := tendsto_map' $
by simp [prod.swap, (∘)]; exact tendsto_map.comp tendsto_swap_uniformity,
comp := calc (map (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧)) u.uniformity).lift' (λs, comp_rel s s) =
u.uniformity.lift' ((λs, comp_rel s s) ∘ image (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧))) :
map_lift'_eq2 $ monotone_comp_rel monotone_id monotone_id
... ≤ u.uniformity.lift' (image (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧)) ∘ (λs:set (α×α), comp_rel s (comp_rel s s))) :
lift'_mono' $ assume s hs ⟨a, b⟩ ⟨c, ⟨⟨a₁, a₂⟩, ha, a_eq⟩, ⟨⟨b₁, b₂⟩, hb, b_eq⟩⟩,
begin
simp at a_eq,
simp at b_eq,
have h : ⟦a₂⟧ = ⟦b₁⟧, { rw [a_eq.right, b_eq.left] },
have h : (a₂, b₁) ∈ separation_rel α := quotient.exact h,
simp [function.comp, set.image, comp_rel, and.comm, and.left_comm, and.assoc],
exact ⟨a₁, a_eq.left, b₂, b_eq.right, a₂, ha, b₁, h s hs, hb⟩
end
... = map (λp:(α×α), (⟦p.1⟧, ⟦p.2⟧)) (u.uniformity.lift' (λs:set (α×α), comp_rel s (comp_rel s s))) :
by rw [map_lift'_eq];
exact monotone_comp_rel monotone_id (monotone_comp_rel monotone_id monotone_id)
... ≤ map (λp:(α×α), (⟦p.1⟧, ⟦p.2⟧)) u.uniformity :
map_mono comp_le_uniformity3,
is_open_uniformity := assume s,
have ∀a, ⟦a⟧ ∈ s →
({p:α×α | p.1 = a → ⟦p.2⟧ ∈ s} ∈ 𝓤 α ↔
{p:α×α | p.1 ≈ a → ⟦p.2⟧ ∈ s} ∈ 𝓤 α),
from assume a ha,
⟨assume h,
let ⟨t, ht, hts⟩ := comp_mem_uniformity_sets h in
have hts : ∀{a₁ a₂}, (a, a₁) ∈ t → (a₁, a₂) ∈ t → ⟦a₂⟧ ∈ s,
from assume a₁ a₂ ha₁ ha₂, @hts (a, a₂) ⟨a₁, ha₁, ha₂⟩ rfl,
have ht' : ∀{a₁ a₂}, a₁ ≈ a₂ → (a₁, a₂) ∈ t,
from assume a₁ a₂ h, sInter_subset_of_mem ht h,
u.uniformity.sets_of_superset ht $ assume ⟨a₁, a₂⟩ h₁ h₂, hts (ht' $ setoid.symm h₂) h₁,
assume h, u.uniformity.sets_of_superset h $ by simp {contextual := tt}⟩,
begin
simp [topological_space.coinduced, u.is_open_uniformity, uniformity, forall_quotient_iff],
exact ⟨λh a ha, (this a ha).mp $ h a ha, λh a ha, (this a ha).mpr $ h a ha⟩
end }
lemma uniformity_quotient :
𝓤 (quotient (separation_setoid α)) = (𝓤 α).map (λp:(α×α), (⟦p.1⟧, ⟦p.2⟧)) :=
rfl
lemma uniform_continuous_quotient_mk :
uniform_continuous (quotient.mk : α → quotient (separation_setoid α)) :=
le_refl _
lemma uniform_continuous_quotient {f : quotient (separation_setoid α) → β}
(hf : uniform_continuous (λx, f ⟦x⟧)) : uniform_continuous f :=
hf
lemma uniform_continuous_quotient_lift
{f : α → β} {h : ∀a b, (a, b) ∈ separation_rel α → f a = f b}
(hf : uniform_continuous f) : uniform_continuous (λa, quotient.lift f h a) :=
uniform_continuous_quotient hf
lemma uniform_continuous_quotient_lift₂ [uniform_space γ]
{f : α → β → γ} {h : ∀a c b d, (a, b) ∈ separation_rel α → (c, d) ∈ separation_rel β → f a c = f b d}
(hf : uniform_continuous (λp:α×β, f p.1 p.2)) :
uniform_continuous (λp:_×_, quotient.lift₂ f h p.1 p.2) :=
begin
rw [uniform_continuous, uniformity_prod_eq_prod, uniformity_quotient, uniformity_quotient,
filter.prod_map_map_eq, filter.tendsto_map'_iff, filter.tendsto_map'_iff],
rwa [uniform_continuous, uniformity_prod_eq_prod, filter.tendsto_map'_iff] at hf
end
lemma comap_quotient_le_uniformity :
(𝓤 $ quotient $ separation_setoid α).comap (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧)) ≤ (𝓤 α) :=
assume t' ht',
let ⟨t, ht, tt_t'⟩ := comp_mem_uniformity_sets ht' in
let ⟨s, hs, ss_t⟩ := comp_mem_uniformity_sets ht in
⟨(λp:α×α, (⟦p.1⟧, ⟦p.2⟧)) '' s,
(𝓤 α).sets_of_superset hs $ assume x hx, ⟨x, hx, rfl⟩,
assume ⟨a₁, a₂⟩ ⟨⟨b₁, b₂⟩, hb, ab_eq⟩,
have ⟦b₁⟧ = ⟦a₁⟧ ∧ ⟦b₂⟧ = ⟦a₂⟧, from prod.mk.inj ab_eq,
have b₁ ≈ a₁ ∧ b₂ ≈ a₂, from and.imp quotient.exact quotient.exact this,
have ab₁ : (a₁, b₁) ∈ t, from (setoid.symm this.left) t ht,
have ba₂ : (b₂, a₂) ∈ s, from this.right s hs,
tt_t' ⟨b₁, show ((a₁, a₂).1, b₁) ∈ t, from ab₁,
ss_t ⟨b₂, show ((b₁, a₂).1, b₂) ∈ s, from hb, ba₂⟩⟩⟩
lemma comap_quotient_eq_uniformity :
(𝓤 $ quotient $ separation_setoid α).comap (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧)) = 𝓤 α :=
le_antisymm comap_quotient_le_uniformity le_comap_map
instance separated_separation : separated (quotient (separation_setoid α)) :=
set.ext $ assume ⟨a, b⟩, quotient.induction_on₂ a b $ assume a b,
⟨assume h,
have a ≈ b, from assume s hs,
have s ∈ (𝓤 $ quotient $ separation_setoid α).comap (λp:(α×α), (⟦p.1⟧, ⟦p.2⟧)),
from comap_quotient_le_uniformity hs,
let ⟨t, ht, hts⟩ := this in
hts begin dsimp [preimage], exact h t ht end,
show ⟦a⟧ = ⟦b⟧, from quotient.sound this,
assume heq : ⟦a⟧ = ⟦b⟧, assume h hs,
heq ▸ refl_mem_uniformity hs⟩
lemma separated_of_uniform_continuous {f : α → β} {x y : α}
(H : uniform_continuous f) (h : x ≈ y) : f x ≈ f y :=
assume _ h', h _ (H h')
lemma eq_of_separated_of_uniform_continuous [separated β] {f : α → β} {x y : α}
(H : uniform_continuous f) (h : x ≈ y) : f x = f y :=
separated_def.1 (by apply_instance) _ _ $ separated_of_uniform_continuous H h
def separation_quotient (α : Type*) [uniform_space α] := quotient (separation_setoid α)
namespace separation_quotient
instance : uniform_space (separation_quotient α) := by dunfold separation_quotient ; apply_instance
instance : separated (separation_quotient α) := by dunfold separation_quotient ; apply_instance
def lift [separated β] (f : α → β) : (separation_quotient α → β) :=
if h : uniform_continuous f then
quotient.lift f (λ x y, eq_of_separated_of_uniform_continuous h)
else
λ x, f (classical.inhabited_of_nonempty $ (nonempty_quotient_iff $ separation_setoid α).1 ⟨x⟩).default
lemma lift_mk [separated β] {f : α → β} (h : uniform_continuous f) (a : α) : lift f ⟦a⟧ = f a :=
by rw [lift, dif_pos h]; refl
lemma uniform_continuous_lift [separated β] (f : α → β) : uniform_continuous (lift f) :=
begin
by_cases hf : uniform_continuous f,
{ rw [lift, dif_pos hf], exact uniform_continuous_quotient_lift hf },
{ rw [lift, dif_neg hf], exact uniform_continuous_of_const (assume a b, rfl) }
end
def map (f : α → β) : separation_quotient α → separation_quotient β :=
lift (quotient.mk ∘ f)
lemma map_mk {f : α → β} (h : uniform_continuous f) (a : α) : map f ⟦a⟧ = ⟦f a⟧ :=
by rw [map, lift_mk (uniform_continuous_quotient_mk.comp h)]
lemma uniform_continuous_map (f : α → β) : uniform_continuous (map f) :=
uniform_continuous_lift (quotient.mk ∘ f)
lemma map_unique {f : α → β} (hf : uniform_continuous f)
{g : separation_quotient α → separation_quotient β}
(comm : quotient.mk ∘ f = g ∘ quotient.mk) : map f = g :=
by ext ⟨a⟩;
calc map f ⟦a⟧ = ⟦f a⟧ : map_mk hf a
... = g ⟦a⟧ : congr_fun comm a
lemma map_id : map (@id α) = id :=
map_unique uniform_continuous_id rfl
lemma map_comp {f : α → β} {g : β → γ} (hf : uniform_continuous f) (hg : uniform_continuous g) :
map g ∘ map f = map (g ∘ f) :=
(map_unique (hg.comp hf) $ by simp only [(∘), map_mk, hf, hg]).symm
end separation_quotient
lemma separation_prod {a₁ a₂ : α} {b₁ b₂ : β} : (a₁, b₁) ≈ (a₂, b₂) ↔ a₁ ≈ a₂ ∧ b₁ ≈ b₂ :=
begin
split,
{ assume h,
exact ⟨separated_of_uniform_continuous uniform_continuous_fst h,
separated_of_uniform_continuous uniform_continuous_snd h⟩ },
{ rintros ⟨eqv_α, eqv_β⟩ r r_in,
rw uniformity_prod at r_in,
rcases r_in with ⟨t_α, ⟨r_α, r_α_in, h_α⟩, t_β, ⟨r_β, r_β_in, h_β⟩, H⟩,
let p_α := λ(p : (α × β) × (α × β)), (p.1.1, p.2.1),
let p_β := λ(p : (α × β) × (α × β)), (p.1.2, p.2.2),
have key_α : p_α ((a₁, b₁), (a₂, b₂)) ∈ r_α, { simp [p_α, eqv_α r_α r_α_in] },
have key_β : p_β ((a₁, b₁), (a₂, b₂)) ∈ r_β, { simp [p_β, eqv_β r_β r_β_in] },
exact H ⟨h_α key_α, h_β key_β⟩ },
end
instance separated.prod [separated α] [separated β] : separated (α × β) :=
separated_def.2 $ assume x y H, prod.ext
(eq_of_separated_of_uniform_continuous uniform_continuous_fst H)
(eq_of_separated_of_uniform_continuous uniform_continuous_snd H)
end uniform_space
|
8e8c321ca4524be91e4cb8c0c5ae5de5ab82ce34 | d9d511f37a523cd7659d6f573f990e2a0af93c6f | /src/number_theory/class_number/admissible_absolute_value.lean | 76cb757fac39612484d61d60ddb66e94fbc062d7 | [
"Apache-2.0"
] | permissive | hikari0108/mathlib | b7ea2b7350497ab1a0b87a09d093ecc025a50dfa | a9e7d333b0cfd45f13a20f7b96b7d52e19fa2901 | refs/heads/master | 1,690,483,608,260 | 1,631,541,580,000 | 1,631,541,580,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 5,763 | lean | /-
Copyright (c) 2021 Anne Baanen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Anne Baanen
-/
import algebra.euclidean_absolute_value
import analysis.special_functions.pow
import combinatorics.pigeonhole
/-!
# Admissible absolute values
This file defines a structure `absolute_value.is_admissible` which we use to show the class number
of the ring of integers of a global field is finite.
## Main definitions
* `absolute_value.is_admissible abv` states the absolute value `abv : R → ℤ`
respects the Euclidean domain structure on `R`, and that a large enough set
of elements of `R^n` contains a pair of elements whose remainders are
pointwise close together.
## Main results
* `absolute_value.abs_is_admissible` shows the "standard" absolute value on `ℤ`,
mapping negative `x` to `-x`, is admissible.
* `polynomial.card_pow_degree_is_admissible` shows `card_pow_degree`,
mapping `p : polynomial 𝔽_q` to `q ^ degree p`, is admissible
-/
local infix ` ≺ `:50 := euclidean_domain.r
namespace absolute_value
variables {R : Type*} [euclidean_domain R]
variables (abv : absolute_value R ℤ)
/-- An absolute value `R → ℤ` is admissible if it respects the Euclidean domain
structure and a large enough set of elements in `R^n` will contain a pair of
elements whose remainders are pointwise close together. -/
structure is_admissible extends is_euclidean abv :=
(card : ℝ → ℕ)
(exists_partition' : ∀ (n : ℕ) {ε : ℝ} (hε : 0 < ε) {b : R} (hb : b ≠ 0) (A : fin n → R),
∃ (t : fin n → fin (card ε)),
∀ i₀ i₁, t i₀ = t i₁ → (abv (A i₁ % b - A i₀ % b) : ℝ) < abv b • ε)
attribute [protected] is_admissible.card
namespace is_admissible
variables {abv}
/-- For all `ε > 0` and finite families `A`, we can partition the remainders of `A` mod `b`
into `abv.card ε` sets, such that all elements in each part of remainders are close together. -/
lemma exists_partition {ι : Type*} [fintype ι] {ε : ℝ} (hε : 0 < ε) {b : R} (hb : b ≠ 0)
(A : ι → R) (h : abv.is_admissible) :
∃ (t : ι → fin (h.card ε)),
∀ i₀ i₁, t i₀ = t i₁ → (abv (A i₁ % b - A i₀ % b) : ℝ) < abv b • ε :=
begin
let e := fintype.equiv_fin ι,
obtain ⟨t, ht⟩ := h.exists_partition' (fintype.card ι) hε hb (A ∘ e.symm),
refine ⟨t ∘ e, λ i₀ i₁ h, _⟩,
convert ht (e i₀) (e i₁) h; simp only [e.symm_apply_apply]
end
/-- Any large enough family of vectors in `R^n` has a pair of elements
whose remainders are close together, pointwise. -/
lemma exists_approx_aux (n : ℕ) (h : abv.is_admissible) :
∀ {ε : ℝ} (hε : 0 < ε) {b : R} (hb : b ≠ 0) (A : fin (h.card ε ^ n).succ → (fin n → R)),
∃ (i₀ i₁), (i₀ ≠ i₁) ∧ ∀ k, (abv (A i₁ k % b - A i₀ k % b) : ℝ) < abv b • ε :=
begin
haveI := classical.dec_eq R,
induction n with n ih,
{ intros ε hε b hb A,
refine ⟨0, 1, _, _⟩,
{ simp },
rintros ⟨i, ⟨⟩⟩ },
intros ε hε b hb A,
set M := h.card ε with hM,
-- By the "nicer" pigeonhole principle, we can find a collection `s`
-- of more than `M^n` remainders where the first components lie close together:
obtain ⟨s, s_inj, hs⟩ : ∃ s : fin (M ^ n).succ → fin (M ^ n.succ).succ,
function.injective s ∧
∀ i₀ i₁, (abv (A (s i₁) 0 % b - A (s i₀) 0 % b) : ℝ) < abv b • ε,
{ -- We can partition the `A`s into `M` subsets where
-- the first components lie close together:
obtain ⟨t, ht⟩ : ∃ (t : fin (M ^ n.succ).succ → fin M),
∀ i₀ i₁, t i₀ = t i₁ → (abv (A i₁ 0 % b - A i₀ 0 % b) : ℝ) < abv b • ε :=
h.exists_partition hε hb (λ x, A x 0),
-- Since the `M` subsets contain more than `M * M^n` elements total,
-- there must be a subset that contains more than `M^n` elements.
obtain ⟨s, hs⟩ := @fintype.exists_lt_card_fiber_of_mul_lt_card _ _ _ _ _ t (M ^ n)
(by simpa only [fintype.card_fin, pow_succ] using nat.lt_succ_self (M ^ n.succ) ),
refine ⟨λ i, (finset.univ.filter (λ x, t x = s)).to_list.nth_le i _, _, λ i₀ i₁, ht _ _ _⟩,
{ refine i.2.trans_le _, rwa finset.length_to_list },
{ intros i j h, ext, exact list.nodup_iff_nth_le_inj.mp (finset.nodup_to_list _) _ _ _ _ h },
have : ∀ i h, (finset.univ.filter (λ x, t x = s)).to_list.nth_le i h ∈
finset.univ.filter (λ x, t x = s),
{ intros i h, exact (finset.mem_to_list _).mp (list.nth_le_mem _ _ _) },
obtain ⟨_, h₀⟩ := finset.mem_filter.mp (this i₀ _),
obtain ⟨_, h₁⟩ := finset.mem_filter.mp (this i₁ _),
exact h₀.trans h₁.symm },
-- Since `s` is large enough, there are two elements of `A ∘ s`
-- where the second components lie close together.
obtain ⟨k₀, k₁, hk, h⟩ := ih hε hb (λ x, fin.tail (A (s x))),
refine ⟨s k₀, s k₁, λ h, hk (s_inj h), λ i, fin.cases _ (λ i, _) i⟩,
{ exact hs k₀ k₁ },
{ exact h i },
end
/-- Any large enough family of vectors in `R^ι` has a pair of elements
whose remainders are close together, pointwise. -/
lemma exists_approx {ι : Type*} [fintype ι] {ε : ℝ} (hε : 0 < ε) {b : R} (hb : b ≠ 0)
(h : abv.is_admissible)
(A : fin (h.card ε ^ fintype.card ι).succ → ι → R) :
∃ (i₀ i₁), (i₀ ≠ i₁) ∧ ∀ k, (abv (A i₁ k % b - A i₀ k % b) : ℝ) < abv b • ε :=
begin
let e := fintype.equiv_fin ι,
obtain ⟨i₀, i₁, ne, h⟩ := h.exists_approx_aux (fintype.card ι) hε hb (λ x y, A x (e.symm y)),
refine ⟨i₀, i₁, ne, λ k, _⟩,
convert h (e k); simp only [e.symm_apply_apply]
end
end is_admissible
end absolute_value
|
9174afd78d06c0f25c5062edf678448f4bc39483 | 624f6f2ae8b3b1adc5f8f67a365c51d5126be45a | /tests/elabissues/issues8.lean | fea4289061c2989bb9b47d5c67610d2423422ede | [
"Apache-2.0"
] | permissive | mhuisi/lean4 | 28d35a4febc2e251c7f05492e13f3b05d6f9b7af | dda44bc47f3e5d024508060dac2bcb59fd12e4c0 | refs/heads/master | 1,621,225,489,283 | 1,585,142,689,000 | 1,585,142,689,000 | 250,590,438 | 0 | 2 | Apache-2.0 | 1,602,443,220,000 | 1,585,327,814,000 | C | UTF-8 | Lean | false | false | 759 | lean | def forceNat (a : Nat) := true
def forceInt (a : Int) := false
def f1 :=
/-
The following example works, but it adds a coercion at `forceInt i`.
The elaborated term is
```
fun (n i : Nat) => if n == i then forceNat n else forceInt (coe i)
-/
fun n i => if n == i then forceNat n else forceInt i -- works
def f2 :=
fun n i => if coe n == i then forceInt i else forceNat n -- works
#check f1 -- Nat → Nat → Bool
#check f2 -- Nat → Int → Bool
def f3 :=
/- Fails.
- `n == i` generates type constraint enforcing `n` and `i` to have the same type.
- `forceInt i` forces `i` (and consequently `n`) to have type `Int`.
- `forceNat n` fails because there is no coercion from `Nat` to `Int`. -/
fun n i => if n == i then forceInt i else forceNat n
|
1eaaaaf88582e0bf049d66d002e6833903059f37 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/algebra/category/Module/subobject.lean | 226ba8b43b8761532f3d3d8fe50b154b75973df8 | [
"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 | 3,523 | lean | /-
Copyright (c) 2021 Markus Himmel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Markus Himmel
-/
import algebra.category.Module.epi_mono
import algebra.category.Module.kernels
import category_theory.subobject.well_powered
import category_theory.subobject.limits
import category_theory.limits.concrete_category
/-!
# Subobjects in the category of `R`-modules
We construct an explicit order isomorphism between the categorical subobjects of an `R`-module `M`
and its submodules. This immediately implies that the category of `R`-modules is well-powered.
-/
open category_theory
open category_theory.subobject
open category_theory.limits
open_locale Module
universes v u
namespace Module
variables {R : Type u} [ring R] (M : Module.{v} R)
/-- The categorical subobjects of a module `M` are in one-to-one correspondence with its
submodules.-/
noncomputable def subobject_Module : subobject M ≃o submodule R M := order_iso.symm
({ inv_fun := λ S, S.arrow.range,
to_fun := λ N, subobject.mk ↾N.subtype,
right_inv := λ S, eq.symm
begin
fapply eq_mk_of_comm,
{ apply linear_equiv.to_Module_iso'_left,
apply linear_equiv.of_bijective (linear_map.cod_restrict S.arrow.range S.arrow _),
{ simpa only [← linear_map.ker_eq_bot, linear_map.ker_cod_restrict]
using ker_eq_bot_of_mono _ },
{ rw [← linear_map.range_eq_top, linear_map.range_cod_restrict,
submodule.comap_subtype_self] },
{ exact linear_map.mem_range_self _ } },
{ apply linear_map.ext,
intros x,
refl }
end,
left_inv := λ N,
begin
convert congr_arg linear_map.range (underlying_iso_arrow ↾N.subtype) using 1,
{ have : (underlying_iso ↾N.subtype).inv = (underlying_iso ↾N.subtype).symm.to_linear_equiv,
{ apply linear_map.ext,
intros x,
refl },
rw [this, comp_def, linear_equiv.range_comp] },
{ exact (submodule.range_subtype _).symm }
end,
map_rel_iff' := λ S T,
begin
refine ⟨λ h, _, λ h, mk_le_mk_of_comm ↟(submodule.of_le h) (by { ext, refl })⟩,
convert linear_map.range_comp_le_range (of_mk_le_mk _ _ h) ↾T.subtype,
{ simpa only [←comp_def, of_mk_le_mk_comp] using (submodule.range_subtype _).symm },
{ exact (submodule.range_subtype _).symm }
end })
instance well_powered_Module : well_powered (Module.{v} R) :=
⟨λ M, ⟨⟨_, ⟨(subobject_Module M).to_equiv⟩⟩⟩⟩
local attribute [instance] has_kernels_Module
/-- Bundle an element `m : M` such that `f m = 0` as a term of `kernel_subobject f`. -/
noncomputable def to_kernel_subobject {M N : Module R} {f : M ⟶ N} :
linear_map.ker f →ₗ[R] kernel_subobject f :=
(kernel_subobject_iso f ≪≫ Module.kernel_iso_ker f).inv
@[simp] lemma to_kernel_subobject_arrow {M N : Module R} {f : M ⟶ N} (x : linear_map.ker f) :
(kernel_subobject f).arrow (to_kernel_subobject x) = x.1 :=
by simp [to_kernel_subobject]
/--
An extensionality lemma showing that two elements of a cokernel by an image
are equal if they differ by an element of the image.
The application is for homology:
two elements in homology are equal if they differ by a boundary.
-/
@[ext]
lemma cokernel_π_image_subobject_ext {L M N : Module.{v} R}
(f : L ⟶ M) [has_image f] (g : (image_subobject f : Module.{v} R) ⟶ N) [has_cokernel g]
{x y : N} (l : L) (w : x = y + g (factor_thru_image_subobject f l)) :
cokernel.π g x = cokernel.π g y :=
by { subst w, simp, }
end Module
|
336e32898961b490dd5f6cca4c50aec445fba42f | 80cc5bf14c8ea85ff340d1d747a127dcadeb966f | /src/algebra/module/ordered.lean | 4e07abc390210304a90b9892c3b29a02dc6033bb | [
"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 | 3,594 | 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 algebra.module.basic
import algebra.ordered_group
/-!
# Ordered semimodules
In this file we define
* `ordered_semimodule R M` : an ordered additive commutative monoid `M` is an `ordered_semimodule`
over an `ordered_semiring` `R` if the scalar product respects the order relation on the
monoid and on the ring. There is a correspondence between this structure and convex cones,
which is proven in `analysis/convex/cone.lean`.
## Implementation notes
* We choose to define `ordered_semimodule` so that it extends `semimodule` only, as is done
for semimodules itself.
* To get ordered modules and ordered vector spaces, it suffices to the replace the
`order_add_comm_monoid` and the `ordered_semiring` as desired.
## References
* https://en.wikipedia.org/wiki/Ordered_vector_space
## Tags
ordered semimodule, ordered module, ordered vector space
-/
/--
An ordered semimodule is an ordered additive commutative monoid
with a partial order in which the scalar multiplication is compatible with the order.
-/
@[protect_proj, ancestor semimodule]
class ordered_semimodule (R β : Type*)
[ordered_semiring R] [ordered_add_comm_monoid β] extends semimodule R β :=
(smul_lt_smul_of_pos : ∀ {a b : β}, ∀ {c : R}, a < b → 0 < c → c • a < c • b)
(lt_of_smul_lt_smul_of_nonneg : ∀ {a b : β}, ∀ {c : R}, c • a < c • b → 0 ≤ c → a < b)
section ordered_semimodule
variables {R β : Type*} [ordered_semiring R] [ordered_add_comm_monoid β] [ordered_semimodule R β]
{a b : β} {c : R}
lemma smul_lt_smul_of_pos : a < b → 0 < c → c • a < c • b := ordered_semimodule.smul_lt_smul_of_pos
lemma smul_le_smul_of_nonneg (h₁ : a ≤ b) (h₂ : 0 ≤ c) : c • a ≤ c • b :=
begin
by_cases H₁ : c = 0,
{ simp [H₁, zero_smul] },
{ by_cases H₂ : a = b,
{ rw H₂ },
{ exact le_of_lt
(smul_lt_smul_of_pos (lt_of_le_of_ne h₁ H₂) (lt_of_le_of_ne h₂ (ne.symm H₁))), } }
end
end ordered_semimodule
section instances
variables {R : Type*} [linear_ordered_ring R]
instance linear_ordered_ring.to_ordered_semimodule : ordered_semimodule R R :=
{ smul_lt_smul_of_pos := ordered_semiring.mul_lt_mul_of_pos_left,
lt_of_smul_lt_smul_of_nonneg := λ _ _ _, lt_of_mul_lt_mul_left }
end instances
section order_dual
variables {R β : Type*}
instance [semiring R] [ordered_add_comm_monoid β] [semimodule R β] : has_scalar R (order_dual β) :=
{ smul := @has_scalar.smul R β _ }
instance [semiring R] [ordered_add_comm_monoid β] [semimodule R β] : mul_action R (order_dual β) :=
{ one_smul := @mul_action.one_smul R β _ _,
mul_smul := @mul_action.mul_smul R β _ _ }
instance [semiring R] [ordered_add_comm_monoid β] [semimodule R β] : distrib_mul_action R (order_dual β) :=
{ smul_add := @distrib_mul_action.smul_add R β _ _ _,
smul_zero := @distrib_mul_action.smul_zero R β _ _ _ }
instance [semiring R] [ordered_add_comm_monoid β] [semimodule R β] : semimodule R (order_dual β) :=
{ add_smul := @semimodule.add_smul R β _ _ _,
zero_smul := @semimodule.zero_smul R β _ _ _ }
instance [ordered_semiring R] [ordered_add_comm_monoid β] [ordered_semimodule R β] :
ordered_semimodule R (order_dual β) :=
{ smul_lt_smul_of_pos := λ a b, @ordered_semimodule.smul_lt_smul_of_pos R β _ _ _ b a,
lt_of_smul_lt_smul_of_nonneg := λ a b, @ordered_semimodule.lt_of_smul_lt_smul_of_nonneg R β _ _ _ b a }
end order_dual
|
6033a52c13ca3915890bd967fa637e5585570f7d | d1a52c3f208fa42c41df8278c3d280f075eb020c | /src/Lean/Elab/Term.lean | 2bf15f500113fbafe05650c16c291056ba4d06e2 | [
"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 | cipher1024/lean4 | 6e1f98bb58e7a92b28f5364eb38a14c8d0aae393 | 69114d3b50806264ef35b57394391c3e738a9822 | refs/heads/master | 1,642,227,983,603 | 1,642,011,696,000 | 1,642,011,696,000 | 228,607,691 | 0 | 0 | Apache-2.0 | 1,576,584,269,000 | 1,576,584,268,000 | null | UTF-8 | Lean | false | false | 69,872 | 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, Sebastian Ullrich
-/
import Lean.ResolveName
import Lean.Util.Sorry
import Lean.Util.ReplaceExpr
import Lean.Structure
import Lean.Meta.AppBuilder
import Lean.Meta.CollectMVars
import Lean.Meta.Coe
import Lean.Hygiene
import Lean.Util.RecDepth
import Lean.Elab.Log
import Lean.Elab.Config
import Lean.Elab.Level
import Lean.Elab.Attributes
import Lean.Elab.AutoBound
import Lean.Elab.InfoTree
import Lean.Elab.Open
import Lean.Elab.SetOption
namespace Lean.Elab.Term
structure Context where
fileName : String
fileMap : FileMap
declName? : Option Name := none
macroStack : MacroStack := []
currMacroScope : MacroScope := firstFrontendMacroScope
/- When `mayPostpone == true`, an elaboration function may interrupt its execution by throwing `Exception.postpone`.
The function `elabTerm` catches this exception and creates fresh synthetic metavariable `?m`, stores `?m` in
the list of pending synthetic metavariables, and returns `?m`. -/
mayPostpone : Bool := true
/- When `errToSorry` is set to true, the method `elabTerm` catches
exceptions and converts them into synthetic `sorry`s.
The implementation of choice nodes and overloaded symbols rely on the fact
that when `errToSorry` is set to false for an elaboration function `F`, then
`errToSorry` remains `false` for all elaboration functions invoked by `F`.
That is, it is safe to transition `errToSorry` from `true` to `false`, but
we must not set `errToSorry` to `true` when it is currently set to `false`. -/
errToSorry : Bool := true
/- When `autoBoundImplicit` is set to true, instead of producing
an "unknown identifier" error for unbound variables, we generate an
internal exception. This exception is caught at `elabBinders` and
`elabTypeWithUnboldImplicit`. Both methods add implicit declarations
for the unbound variable and try again. -/
autoBoundImplicit : Bool := false
autoBoundImplicits : Std.PArray Expr := {}
/-- Map from user name to internal unique name -/
sectionVars : NameMap Name := {}
/-- Map from internal name to fvar -/
sectionFVars : NameMap Expr := {}
/-- Enable/disable implicit lambdas feature. -/
implicitLambda : Bool := true
/-- noncomputable sections automatically add the `noncomputable` modifier to any declaration we cannot generate code for -/
isNoncomputableSection : Bool := false
/-- Saved context for postponed terms and tactics to be executed. -/
structure SavedContext where
declName? : Option Name
options : Options
openDecls : List OpenDecl
macroStack : MacroStack
errToSorry : Bool
/-- We use synthetic metavariables as placeholders for pending elaboration steps. -/
inductive SyntheticMVarKind where
-- typeclass instance search
| typeClass
/- Similar to typeClass, but error messages are different.
if `f?` is `some f`, we produce an application type mismatch error message.
Otherwise, if `header?` is `some header`, we generate the error `(header ++ "has type" ++ eType ++ "but it is expected to have type" ++ expectedType)`
Otherwise, we generate the error `("type mismatch" ++ e ++ "has type" ++ eType ++ "but it is expected to have type" ++ expectedType)` -/
| coe (header? : Option String) (eNew : Expr) (expectedType : Expr) (eType : Expr) (e : Expr) (f? : Option Expr)
-- tactic block execution
| tactic (tacticCode : Syntax) (ctx : SavedContext)
-- `elabTerm` call that threw `Exception.postpone` (input is stored at `SyntheticMVarDecl.ref`)
| postponed (ctx : SavedContext)
instance : ToString SyntheticMVarKind where
toString
| SyntheticMVarKind.typeClass => "typeclass"
| SyntheticMVarKind.coe .. => "coe"
| SyntheticMVarKind.tactic .. => "tactic"
| SyntheticMVarKind.postponed .. => "postponed"
structure SyntheticMVarDecl where
mvarId : MVarId
stx : Syntax
kind : SyntheticMVarKind
inductive MVarErrorKind where
| implicitArg (ctx : Expr)
| hole
| custom (msgData : MessageData)
deriving Inhabited
instance : ToString MVarErrorKind where
toString
| MVarErrorKind.implicitArg ctx => "implicitArg"
| MVarErrorKind.hole => "hole"
| MVarErrorKind.custom msg => "custom"
structure MVarErrorInfo where
mvarId : MVarId
ref : Syntax
kind : MVarErrorKind
argName? : Option Name := none
deriving Inhabited
structure LetRecToLift where
ref : Syntax
fvarId : FVarId
attrs : Array Attribute
shortDeclName : Name
declName : Name
lctx : LocalContext
localInstances : LocalInstances
type : Expr
val : Expr
mvarId : MVarId
structure State where
levelNames : List Name := []
syntheticMVars : List SyntheticMVarDecl := []
mvarErrorInfos : MVarIdMap MVarErrorInfo := {}
messages : MessageLog := {}
letRecsToLift : List LetRecToLift := []
infoState : InfoState := {}
deriving Inhabited
abbrev TermElabM := ReaderT Context $ StateRefT State MetaM
abbrev TermElab := Syntax → Option Expr → TermElabM Expr
-- 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 TermElabM := let i := inferInstanceAs (Monad TermElabM); { pure := i.pure, bind := i.bind }
open Meta
instance : Inhabited (TermElabM α) where
default := throw arbitrary
structure SavedState where
meta : Meta.SavedState
«elab» : State
deriving Inhabited
protected def saveState : TermElabM SavedState := do
pure { meta := (← Meta.saveState), «elab» := (← get) }
def SavedState.restore (s : SavedState) (restoreInfo : Bool := false) : TermElabM Unit := do
let traceState ← getTraceState -- We never backtrack trace message
let infoState := (← get).infoState -- We also do not backtrack the info nodes when `restoreInfo == false`
s.meta.restore
set s.elab
setTraceState traceState
unless restoreInfo do
modify fun s => { s with infoState := infoState }
instance : MonadBacktrack SavedState TermElabM where
saveState := Term.saveState
restoreState b := b.restore
abbrev TermElabResult (α : Type) := EStateM.Result Exception SavedState α
instance [Inhabited α] : Inhabited (TermElabResult α) where
default := EStateM.Result.ok arbitrary arbitrary
def setMessageLog (messages : MessageLog) : TermElabM Unit :=
modify fun s => { s with messages := messages }
def resetMessageLog : TermElabM Unit :=
setMessageLog {}
def getMessageLog : TermElabM MessageLog :=
return (← get).messages
/--
Execute `x`, save resulting expression and new state.
We remove any `Info` created by `x`.
The info nodes are committed when we execute `applyResult`.
We use `observing` to implement overloaded notation and decls.
We want to save `Info` nodes for the chosen alternative.
-/
def observing (x : TermElabM α) : TermElabM (TermElabResult α) := do
let s ← saveState
try
let e ← x
let sNew ← saveState
s.restore (restoreInfo := true)
pure (EStateM.Result.ok e sNew)
catch
| ex@(Exception.error _ _) =>
let sNew ← saveState
s.restore (restoreInfo := true)
pure (EStateM.Result.error ex sNew)
| ex@(Exception.internal id _) =>
if id == postponeExceptionId then
s.restore (restoreInfo := true)
throw ex
/--
Apply the result/exception and state captured with `observing`.
We use this method to implement overloaded notation and symbols. -/
def applyResult (result : TermElabResult α) : TermElabM α :=
match result with
| EStateM.Result.ok a r => do r.restore (restoreInfo := true); pure a
| EStateM.Result.error ex r => do r.restore (restoreInfo := true); throw ex
/--
Execute `x`, but keep state modifications only if `x` did not postpone.
This method is useful to implement elaboration functions that cannot decide whether
they need to postpone or not without updating the state. -/
def commitIfDidNotPostpone (x : TermElabM α) : TermElabM α := do
-- We just reuse the implementation of `observing` and `applyResult`.
let r ← observing x
applyResult r
def getLevelNames : TermElabM (List Name) :=
return (← get).levelNames
def getFVarLocalDecl! (fvar : Expr) : TermElabM LocalDecl := do
match (← getLCtx).find? fvar.fvarId! with
| some d => pure d
| none => unreachable!
instance : AddErrorMessageContext TermElabM where
add ref msg := do
let ctx ← read
let ref := getBetterRef ref ctx.macroStack
let msg ← addMessageContext msg
let msg ← addMacroStack msg ctx.macroStack
pure (ref, msg)
instance : MonadLog TermElabM where
getRef := getRef
getFileMap := return (← read).fileMap
getFileName := return (← read).fileName
logMessage msg := do
let ctx ← readThe Core.Context
let msg := { msg with data := MessageData.withNamingContext { currNamespace := ctx.currNamespace, openDecls := ctx.openDecls } msg.data };
modify fun s => { s with messages := s.messages.add msg }
protected def getCurrMacroScope : TermElabM MacroScope := do pure (← read).currMacroScope
protected def getMainModule : TermElabM Name := do pure (← getEnv).mainModule
protected def withFreshMacroScope (x : TermElabM α) : TermElabM α := do
let fresh ← modifyGetThe Core.State (fun st => (st.nextMacroScope, { st with nextMacroScope := st.nextMacroScope + 1 }))
withReader (fun ctx => { ctx with currMacroScope := fresh }) x
instance : MonadQuotation TermElabM where
getCurrMacroScope := Term.getCurrMacroScope
getMainModule := Term.getMainModule
withFreshMacroScope := Term.withFreshMacroScope
instance : MonadInfoTree TermElabM where
getInfoState := return (← get).infoState
modifyInfoState f := modify fun s => { s with infoState := f s.infoState }
/--
Execute `x` but discard changes performed at `Term.State` and `Meta.State`.
Recall that the environment is at `Core.State`. Thus, any updates to it will
be preserved. This method is useful for performing computations where all
metavariable must be resolved or discarded.
The info trees are not discarded, however, and wrapped in `InfoTree.Context`
to store their metavariable context. -/
def withoutModifyingElabMetaStateWithInfo (x : TermElabM α) : TermElabM α := do
let s ← get
let sMeta ← getThe Meta.State
try
withSaveInfoContext x
finally
modify ({ s with infoState := ·.infoState })
set sMeta
/--
Execute `x` bud discard changes performed to the state.
However, the info trees and messages are not discarded. -/
private def withoutModifyingStateWithInfoAndMessagesImpl (x : TermElabM α) : TermElabM α := do
let saved ← saveState
try
x
finally
let s ← get
let saved := { saved with elab.infoState := s.infoState, elab.messages := s.messages }
restoreState saved
unsafe def mkTermElabAttributeUnsafe : IO (KeyedDeclsAttribute TermElab) :=
mkElabAttribute TermElab `Lean.Elab.Term.termElabAttribute `builtinTermElab `termElab `Lean.Parser.Term `Lean.Elab.Term.TermElab "term"
@[implementedBy mkTermElabAttributeUnsafe]
constant mkTermElabAttribute : IO (KeyedDeclsAttribute TermElab)
builtin_initialize termElabAttribute : KeyedDeclsAttribute TermElab ← mkTermElabAttribute
/--
Auxiliary datatatype for presenting a Lean lvalue modifier.
We represent a unelaborated lvalue as a `Syntax` (or `Expr`) and `List LVal`.
Example: `a.foo[i].1` is represented as the `Syntax` `a` and the list
`[LVal.fieldName "foo", LVal.getOp i, LVal.fieldIdx 1]`.
Recall that the notation `a[i]` is not just for accessing arrays in Lean. -/
inductive LVal where
| fieldIdx (ref : Syntax) (i : Nat)
/- Field `suffix?` is for producing better error messages because `x.y` may be a field access or a hierachical/composite name.
`ref` is the syntax object representing the field. `targetStx` is the target object being accessed. -/
| fieldName (ref : Syntax) (name : String) (suffix? : Option Name) (targetStx : Syntax)
| getOp (ref : Syntax) (idx : Syntax)
def LVal.getRef : LVal → Syntax
| LVal.fieldIdx ref _ => ref
| LVal.fieldName ref .. => ref
| LVal.getOp ref _ => ref
def LVal.isFieldName : LVal → Bool
| LVal.fieldName .. => true
| _ => false
instance : ToString LVal where
toString
| LVal.fieldIdx _ i => toString i
| LVal.fieldName _ n .. => n
| LVal.getOp _ idx => "[" ++ toString idx ++ "]"
def getDeclName? : TermElabM (Option Name) := return (← read).declName?
def getLetRecsToLift : TermElabM (List LetRecToLift) := return (← get).letRecsToLift
def isExprMVarAssigned (mvarId : MVarId) : TermElabM Bool := return (← getMCtx).isExprAssigned mvarId
def getMVarDecl (mvarId : MVarId) : TermElabM MetavarDecl := return (← getMCtx).getDecl mvarId
def assignLevelMVar (mvarId : MVarId) (val : Level) : TermElabM Unit := modifyThe Meta.State fun s => { s with mctx := s.mctx.assignLevel mvarId val }
def withDeclName (name : Name) (x : TermElabM α) : TermElabM α :=
withReader (fun ctx => { ctx with declName? := name }) x
def setLevelNames (levelNames : List Name) : TermElabM Unit :=
modify fun s => { s with levelNames := levelNames }
def withLevelNames (levelNames : List Name) (x : TermElabM α) : TermElabM α := do
let levelNamesSaved ← getLevelNames
setLevelNames levelNames
try x finally setLevelNames levelNamesSaved
def withoutErrToSorry (x : TermElabM α) : TermElabM α :=
withReader (fun ctx => { ctx with errToSorry := false }) x
/-- For testing `TermElabM` methods. The #eval command will sign the error. -/
def throwErrorIfErrors : TermElabM Unit := do
if (← get).messages.hasErrors then
throwError "Error(s)"
def traceAtCmdPos (cls : Name) (msg : Unit → MessageData) : TermElabM Unit :=
withRef Syntax.missing $ trace cls msg
def ppGoal (mvarId : MVarId) : TermElabM Format :=
Meta.ppGoal mvarId
open Level (LevelElabM)
def liftLevelM (x : LevelElabM α) : TermElabM α := do
let ctx ← read
let mctx ← getMCtx
let ngen ← getNGen
let lvlCtx : Level.Context := { options := (← getOptions), ref := (← getRef), autoBoundImplicit := ctx.autoBoundImplicit }
match (x lvlCtx).run { ngen := ngen, mctx := mctx, levelNames := (← getLevelNames) } with
| EStateM.Result.ok a newS => setMCtx newS.mctx; setNGen newS.ngen; setLevelNames newS.levelNames; pure a
| EStateM.Result.error ex _ => throw ex
def elabLevel (stx : Syntax) : TermElabM Level :=
liftLevelM $ Level.elabLevel stx
/- Elaborate `x` with `stx` on the macro stack -/
def withMacroExpansion (beforeStx afterStx : Syntax) (x : TermElabM α) : TermElabM α :=
withMacroExpansionInfo beforeStx afterStx do
withReader (fun ctx => { ctx with macroStack := { before := beforeStx, after := afterStx } :: ctx.macroStack }) x
/-
Add the given metavariable to the list of pending synthetic metavariables.
The method `synthesizeSyntheticMVars` is used to process the metavariables on this list. -/
def registerSyntheticMVar (stx : Syntax) (mvarId : MVarId) (kind : SyntheticMVarKind) : TermElabM Unit := do
modify fun s => { s with syntheticMVars := { mvarId := mvarId, stx := stx, kind := kind } :: s.syntheticMVars }
def registerSyntheticMVarWithCurrRef (mvarId : MVarId) (kind : SyntheticMVarKind) : TermElabM Unit := do
registerSyntheticMVar (← getRef) mvarId kind
def registerMVarErrorInfo (mvarErrorInfo : MVarErrorInfo) : TermElabM Unit :=
modify fun s => { s with mvarErrorInfos := s.mvarErrorInfos.insert mvarErrorInfo.mvarId mvarErrorInfo }
def registerMVarErrorHoleInfo (mvarId : MVarId) (ref : Syntax) : TermElabM Unit :=
registerMVarErrorInfo { mvarId := mvarId, ref := ref, kind := MVarErrorKind.hole }
def registerMVarErrorImplicitArgInfo (mvarId : MVarId) (ref : Syntax) (app : Expr) : TermElabM Unit := do
registerMVarErrorInfo { mvarId := mvarId, ref := ref, kind := MVarErrorKind.implicitArg app }
def registerMVarErrorCustomInfo (mvarId : MVarId) (ref : Syntax) (msgData : MessageData) : TermElabM Unit := do
registerMVarErrorInfo { mvarId := mvarId, ref := ref, kind := MVarErrorKind.custom msgData }
def getMVarErrorInfo? (mvarId : MVarId) : TermElabM (Option MVarErrorInfo) := do
return (← get).mvarErrorInfos.find? mvarId
def registerCustomErrorIfMVar (e : Expr) (ref : Syntax) (msgData : MessageData) : TermElabM Unit :=
match e.getAppFn with
| Expr.mvar mvarId _ => registerMVarErrorCustomInfo mvarId ref msgData
| _ => pure ()
/-
Auxiliary method for reporting errors of the form "... contains metavariables ...".
This kind of error is thrown, for example, at `Match.lean` where elaboration
cannot continue if there are metavariables in patterns.
We only want to log it if we haven't logged any error so far. -/
def throwMVarError (m : MessageData) : TermElabM α := do
if (← get).messages.hasErrors then
throwAbortTerm
else
throwError m
def MVarErrorInfo.logError (mvarErrorInfo : MVarErrorInfo) (extraMsg? : Option MessageData) : TermElabM Unit := do
match mvarErrorInfo.kind with
| MVarErrorKind.implicitArg app => do
let app ← instantiateMVars app
let msg := addArgName "don't know how to synthesize implicit argument"
let msg := msg ++ m!"{indentExpr app.setAppPPExplicitForExposingMVars}" ++ Format.line ++ "context:" ++ Format.line ++ MessageData.ofGoal mvarErrorInfo.mvarId
logErrorAt mvarErrorInfo.ref (appendExtra msg)
| MVarErrorKind.hole => do
let msg := addArgName "don't know how to synthesize placeholder" " for argument"
let msg := msg ++ Format.line ++ "context:" ++ Format.line ++ MessageData.ofGoal mvarErrorInfo.mvarId
logErrorAt mvarErrorInfo.ref (MessageData.tagged `Elab.synthPlaceholder <| appendExtra msg)
| MVarErrorKind.custom msg =>
logErrorAt mvarErrorInfo.ref (appendExtra msg)
where
/-- Append `mvarErrorInfo` argument name (if available) to the message.
Remark: if the argument name contains macro scopes we do not append it. -/
addArgName (msg : MessageData) (extra : String := "") : MessageData :=
match mvarErrorInfo.argName? with
| none => msg
| some argName => if argName.hasMacroScopes then msg else msg ++ extra ++ m!" '{argName}'"
appendExtra (msg : MessageData) : MessageData :=
match extraMsg? with
| none => msg
| some extraMsg => msg ++ extraMsg
/--
Try to log errors for the unassigned metavariables `pendingMVarIds`.
Return `true` if there were "unfilled holes", and we should "abort" declaration.
TODO: try to fill "all" holes using synthetic "sorry's"
Remark: We only log the "unfilled holes" as new errors if no error has been logged so far. -/
def logUnassignedUsingErrorInfos (pendingMVarIds : Array MVarId) (extraMsg? : Option MessageData := none) : TermElabM Bool := do
let s ← get
let hasOtherErrors := s.messages.hasErrors
let mut hasNewErrors := false
let mut alreadyVisited : MVarIdSet := {}
let mut errors : Array MVarErrorInfo := #[]
for (_, mvarErrorInfo) in s.mvarErrorInfos do
let mvarId := mvarErrorInfo.mvarId
unless alreadyVisited.contains mvarId do
alreadyVisited := alreadyVisited.insert mvarId
/- The metavariable `mvarErrorInfo.mvarId` may have been assigned or
delayed assigned to another metavariable that is unassigned. -/
let mvarDeps ← getMVars (mkMVar mvarId)
if mvarDeps.any pendingMVarIds.contains then do
unless hasOtherErrors do
errors := errors.push mvarErrorInfo
hasNewErrors := true
-- To sort the errors by position use
-- let sortedErrors := errors.qsort fun e₁ e₂ => e₁.ref.getPos?.getD 0 < e₂.ref.getPos?.getD 0
for error in errors do
withMVarContext error.mvarId do
error.logError extraMsg?
return hasNewErrors
/-- Ensure metavariables registered using `registerMVarErrorInfos` (and used in the given declaration) have been assigned. -/
def ensureNoUnassignedMVars (decl : Declaration) : TermElabM Unit := do
let pendingMVarIds ← getMVarsAtDecl decl
if (← logUnassignedUsingErrorInfos pendingMVarIds) then
throwAbortCommand
/-
Execute `x` without allowing it to postpone elaboration tasks.
That is, `tryPostpone` is a noop. -/
def withoutPostponing (x : TermElabM α) : TermElabM α :=
withReader (fun ctx => { ctx with mayPostpone := false }) x
/-- Creates syntax for `(` <ident> `:` <type> `)` -/
def mkExplicitBinder (ident : Syntax) (type : Syntax) : Syntax :=
mkNode ``Lean.Parser.Term.explicitBinder #[mkAtom "(", mkNullNode #[ident], mkNullNode #[mkAtom ":", type], mkNullNode, mkAtom ")"]
/--
Convert unassigned universe level metavariables into parameters.
The new parameter names are of the form `u_i` where `i >= nextParamIdx`.
The method returns the updated expression and new `nextParamIdx`.
Remark: we make sure the generated parameter names do not clash with the universe at `ctx.levelNames`. -/
def levelMVarToParam (e : Expr) (nextParamIdx : Nat := 1) : TermElabM (Expr × Nat) := do
let mctx ← getMCtx
let levelNames ← getLevelNames
let r := mctx.levelMVarToParam (fun n => levelNames.elem n) e `u nextParamIdx
setMCtx r.mctx
pure (r.expr, r.nextParamIdx)
/-- Variant of `levelMVarToParam` where `nextParamIdx` is stored in a state monad. -/
def levelMVarToParam' (e : Expr) : StateRefT Nat TermElabM Expr := do
let nextParamIdx ← get
let (e, nextParamIdx) ← levelMVarToParam e nextParamIdx
set nextParamIdx
pure e
/--
Auxiliary method for creating fresh binder names.
Do not confuse with the method for creating fresh free/meta variable ids. -/
def mkFreshBinderName [Monad m] [MonadQuotation m] : m Name :=
withFreshMacroScope $ MonadQuotation.addMacroScope `x
/--
Auxiliary method for creating a `Syntax.ident` containing
a fresh name. This method is intended for creating fresh binder names.
It is just a thin layer on top of `mkFreshUserName`. -/
def mkFreshIdent [Monad m] [MonadQuotation m] (ref : Syntax) : m Syntax :=
return mkIdentFrom ref (← mkFreshBinderName)
private def applyAttributesCore
(declName : Name) (attrs : Array Attribute)
(applicationTime? : Option AttributeApplicationTime) : TermElabM Unit :=
for attr in attrs do
let env ← getEnv
match getAttributeImpl env attr.name with
| Except.error errMsg => throwError errMsg
| Except.ok attrImpl =>
match applicationTime? with
| none => attrImpl.add declName attr.stx attr.kind
| some applicationTime =>
if applicationTime == attrImpl.applicationTime then
attrImpl.add declName attr.stx attr.kind
/-- Apply given attributes **at** a given application time -/
def applyAttributesAt (declName : Name) (attrs : Array Attribute) (applicationTime : AttributeApplicationTime) : TermElabM Unit :=
applyAttributesCore declName attrs applicationTime
def applyAttributes (declName : Name) (attrs : Array Attribute) : TermElabM Unit :=
applyAttributesCore declName attrs none
def mkTypeMismatchError (header? : Option String) (e : Expr) (eType : Expr) (expectedType : Expr) : TermElabM MessageData := do
let header : MessageData := match header? with
| some header => m!"{header} "
| none => m!"type mismatch{indentExpr e}\n"
return m!"{header}{← mkHasTypeButIsExpectedMsg eType expectedType}"
def throwTypeMismatchError (header? : Option String) (expectedType : Expr) (eType : Expr) (e : Expr)
(f? : Option Expr := none) (extraMsg? : Option MessageData := none) : TermElabM α := do
/-
We ignore `extraMsg?` for now. In all our tests, it contained no useful information. It was
always of the form:
```
failed to synthesize instance
CoeT <eType> <e> <expectedType>
```
We should revisit this decision in the future and decide whether it may contain useful information
or not. -/
let extraMsg := Format.nil
/-
let extraMsg : MessageData := match extraMsg? with
| none => Format.nil
| some extraMsg => Format.line ++ extraMsg;
-/
match f? with
| none => throwError "{← mkTypeMismatchError header? e eType expectedType}{extraMsg}"
| some f => Meta.throwAppTypeMismatch f e extraMsg
def withoutMacroStackAtErr (x : TermElabM α) : TermElabM α :=
withTheReader Core.Context (fun (ctx : Core.Context) => { ctx with options := pp.macroStack.set ctx.options false }) x
namespace ContainsPendingMVar
abbrev M := MonadCacheT Expr Unit (OptionT TermElabM)
/-- See `containsPostponedTerm` -/
partial def visit (e : Expr) : M Unit := do
checkCache e fun _ => do
match e with
| Expr.forallE _ d b _ => visit d; visit b
| Expr.lam _ d b _ => visit d; visit b
| Expr.letE _ t v b _ => visit t; visit v; visit b
| Expr.app f a _ => visit f; visit a
| Expr.mdata _ b _ => visit b
| Expr.proj _ _ b _ => visit b
| Expr.fvar fvarId .. =>
match (← getLocalDecl fvarId) with
| LocalDecl.cdecl .. => return ()
| LocalDecl.ldecl (value := v) .. => visit v
| Expr.mvar mvarId .. =>
let e' ← instantiateMVars e
if e' != e then
visit e'
else
match (← getDelayedAssignment? mvarId) with
| some d => visit d.val
| none => failure
| _ => return ()
end ContainsPendingMVar
/-- Return `true` if `e` contains a pending metavariable. Remark: it also visits let-declarations. -/
def containsPendingMVar (e : Expr) : TermElabM Bool := do
match (← ContainsPendingMVar.visit e |>.run.run) with
| some _ => return false
| none => return true
/- Try to synthesize metavariable using type class resolution.
This method assumes the local context and local instances of `instMVar` coincide
with the current local context and local instances.
Return `true` if the instance was synthesized successfully, and `false` if
the instance contains unassigned metavariables that are blocking the type class
resolution procedure. Throw an exception if resolution or assignment irrevocably fails. -/
def synthesizeInstMVarCore (instMVar : MVarId) (maxResultSize? : Option Nat := none) : TermElabM Bool := do
let instMVarDecl ← getMVarDecl instMVar
let type := instMVarDecl.type
let type ← instantiateMVars type
let result ← trySynthInstance type maxResultSize?
match result with
| LOption.some val =>
if (← isExprMVarAssigned instMVar) then
let oldVal ← instantiateMVars (mkMVar instMVar)
unless (← isDefEq oldVal val) do
if (← containsPendingMVar oldVal <||> containsPendingMVar val) then
/- If `val` or `oldVal` contains metavariables directly or indirectly (e.g., in a let-declaration),
we return `false` to indicate we should try again later. This is very course grain since
the metavariable may not be responsible for the failure. We should refine the test in the future if needed.
This check has been added to address dependencies between postponed metavariables. The following
example demonstrates the issue fixed by this test.
```
structure Point where
x : Nat
y : Nat
def Point.compute (p : Point) : Point :=
let p := { p with x := 1 }
let p := { p with y := 0 }
if (p.x - p.y) > p.x then p else p
```
The `isDefEq` test above fails for `Decidable (p.x - p.y ≤ p.x)` when the structure instance assigned to
`p` has not been elaborated yet.
-/
return false -- we will try again later
let oldValType ← inferType oldVal
let valType ← inferType val
unless (← isDefEq oldValType valType) do
throwError "synthesized type class instance type is not definitionally equal to expected type, synthesized{indentExpr val}\nhas type{indentExpr valType}\nexpected{indentExpr oldValType}"
throwError "synthesized type class instance is not definitionally equal to expression inferred by typing rules, synthesized{indentExpr val}\ninferred{indentExpr oldVal}"
else
unless (← isDefEq (mkMVar instMVar) val) do
throwError "failed to assign synthesized type class instance{indentExpr val}"
pure true
| LOption.undef => pure false -- we will try later
| LOption.none => throwError "failed to synthesize instance{indentExpr type}"
register_builtin_option autoLift : Bool := {
defValue := true
descr := "insert monadic lifts (i.e., `liftM` and `liftCoeM`) when needed"
}
register_builtin_option maxCoeSize : Nat := {
defValue := 16
descr := "maximum number of instances used to construct an automatic coercion"
}
def synthesizeCoeInstMVarCore (instMVar : MVarId) : TermElabM Bool := do
synthesizeInstMVarCore instMVar (some (maxCoeSize.get (← getOptions)))
/-
The coercion from `α` to `Thunk α` cannot be implemented using an instance because it would
eagerly evaluate `e` -/
def tryCoeThunk? (expectedType : Expr) (eType : Expr) (e : Expr) : TermElabM (Option Expr) := do
match expectedType with
| Expr.app (Expr.const ``Thunk u _) arg _ =>
if (← isDefEq eType arg) then
pure (some (mkApp2 (mkConst ``Thunk.mk u) arg (mkSimpleThunk e)))
else
pure none
| _ =>
pure none
def mkCoe (expectedType : Expr) (eType : Expr) (e : Expr) (f? : Option Expr := none) (errorMsgHeader? : Option String := none) : TermElabM Expr := do
let u ← getLevel eType
let v ← getLevel expectedType
let coeTInstType := mkAppN (mkConst ``CoeT [u, v]) #[eType, e, expectedType]
let mvar ← mkFreshExprMVar coeTInstType MetavarKind.synthetic
let eNew := mkAppN (mkConst ``coe [u, v]) #[eType, expectedType, e, mvar]
let mvarId := mvar.mvarId!
try
withoutMacroStackAtErr do
if (← synthesizeCoeInstMVarCore mvarId) then
expandCoe eNew
else
-- We create an auxiliary metavariable to represent the result, because we need to execute `expandCoe`
-- after we syntheze `mvar`
let mvarAux ← mkFreshExprMVar expectedType MetavarKind.syntheticOpaque
registerSyntheticMVarWithCurrRef mvarAux.mvarId! (SyntheticMVarKind.coe errorMsgHeader? eNew expectedType eType e f?)
return mvarAux
catch
| Exception.error _ msg => throwTypeMismatchError errorMsgHeader? expectedType eType e f? msg
| _ => throwTypeMismatchError errorMsgHeader? expectedType eType e f?
/--
Try to apply coercion to make sure `e` has type `expectedType`.
Relevant definitions:
```
class CoeT (α : Sort u) (a : α) (β : Sort v)
abbrev coe {α : Sort u} {β : Sort v} (a : α) [CoeT α a β] : β
```
-/
private def tryCoe (errorMsgHeader? : Option String) (expectedType : Expr) (eType : Expr) (e : Expr) (f? : Option Expr) : TermElabM Expr := do
if (← isDefEq expectedType eType) then
return e
else match (← tryCoeThunk? expectedType eType e) with
| some r => return r
| none => mkCoe expectedType eType e f? errorMsgHeader?
def isTypeApp? (type : Expr) : TermElabM (Option (Expr × Expr)) := do
let type ← withReducible $ whnf type
match type with
| Expr.app m α _ => pure (some ((← instantiateMVars m), (← instantiateMVars α)))
| _ => pure none
def synthesizeInst (type : Expr) : TermElabM Expr := do
let type ← instantiateMVars type
match (← trySynthInstance type) with
| LOption.some val => pure val
| LOption.undef => throwError "failed to synthesize instance{indentExpr type}"
| LOption.none => throwError "failed to synthesize instance{indentExpr type}"
def isMonadApp (type : Expr) : TermElabM Bool := do
let some (m, _) ← isTypeApp? type | pure false
return (← isMonad? m) |>.isSome
/--
Try to coerce `a : α` into `m β` by first coercing `a : α` into ‵β`, and then using `pure`.
The method is only applied if `α` is not monadic (e.g., `Nat → IO Unit`), and the head symbol
of the resulting type is not a metavariable (e.g., `?m Unit` or `Bool → ?m Nat`).
The main limitation of the approach above is polymorphic code. As usual, coercions and polymorphism
do not interact well. In the example above, the lift is successfully applied to `true`, `false` and `!y`
since none of them is polymorphic
```
def f (x : Bool) : IO Bool := do
let y ← if x == 0 then IO.println "hello"; true else false;
!y
```
On the other hand, the following fails since `+` is polymorphic
```
def f (x : Bool) : IO Nat := do
IO.prinln x
x + x -- Error: failed to synthesize `Add (IO Nat)`
```
-/
private def tryPureCoe? (errorMsgHeader? : Option String) (m β α a : Expr) : TermElabM (Option Expr) :=
commitWhenSome? do
let doIt : TermElabM (Option Expr) := do
try
let aNew ← tryCoe errorMsgHeader? β α a none
let aNew ← mkPure m aNew
pure (some aNew)
catch _ =>
pure none
forallTelescope α fun _ α => do
if (← isMonadApp α) then
pure none
else if !α.getAppFn.isMVar then
doIt
else
pure none
/-
Try coercions and monad lifts to make sure `e` has type `expectedType`.
If `expectedType` is of the form `n β`, we try monad lifts and other extensions.
Otherwise, we just use the basic `tryCoe`.
Extensions for monads.
Given an expected type of the form `n β`, if `eType` is of the form `α`, but not `m α`
1 - Try to coerce ‵α` into ‵β`, and use `pure` to lift it to `n α`.
It only works if `n` implements `Pure`
If `eType` is of the form `m α`. We use the following approaches.
1- Try to unify `n` and `m`. If it succeeds, then we use
```
coeM {m : Type u → Type v} {α β : Type u} [∀ a, CoeT α a β] [Monad m] (x : m α) : m β
```
`n` must be a `Monad` to use this one.
2- If there is monad lift from `m` to `n` and we can unify `α` and `β`, we use
```
liftM : ∀ {m : Type u_1 → Type u_2} {n : Type u_1 → Type u_3} [self : MonadLiftT m n] {α : Type u_1}, m α → n α
```
Note that `n` may not be a `Monad` in this case. This happens quite a bit in code such as
```
def g (x : Nat) : IO Nat := do
IO.println x
pure x
def f {m} [MonadLiftT IO m] : m Nat :=
g 10
```
3- If there is a monad lif from `m` to `n` and a coercion from `α` to `β`, we use
```
liftCoeM {m : Type u → Type v} {n : Type u → Type w} {α β : Type u} [MonadLiftT m n] [∀ a, CoeT α a β] [Monad n] (x : m α) : n β
```
Note that approach 3 does not subsume 1 because it is only applicable if there is a coercion from `α` to `β` for all values in `α`.
This is not the case for example for `pure $ x > 0` when the expected type is `IO Bool`. The given type is `IO Prop`, and
we only have a coercion from decidable propositions. Approach 1 works because it constructs the coercion `CoeT (m Prop) (pure $ x > 0) (m Bool)`
using the instance `pureCoeDepProp`.
Note that, approach 2 is more powerful than `tryCoe`.
Recall that type class resolution never assigns metavariables created by other modules.
Now, consider the following scenario
```lean
def g (x : Nat) : IO Nat := ...
deg h (x : Nat) : StateT Nat IO Nat := do
v ← g x;
IO.Println v;
...
```
Let's assume there is no other occurrence of `v` in `h`.
Thus, we have that the expected of `g x` is `StateT Nat IO ?α`,
and the given type is `IO Nat`. So, even if we add a coercion.
```
instance {α m n} [MonadLiftT m n] {α} : Coe (m α) (n α) := ...
```
It is not applicable because TC would have to assign `?α := Nat`.
On the other hand, TC can easily solve `[MonadLiftT IO (StateT Nat IO)]`
since this goal does not contain any metavariables. And then, we
convert `g x` into `liftM $ g x`.
-/
private def tryLiftAndCoe (errorMsgHeader? : Option String) (expectedType : Expr) (eType : Expr) (e : Expr) (f? : Option Expr) : TermElabM Expr := do
let expectedType ← instantiateMVars expectedType
let eType ← instantiateMVars eType
let throwMismatch {α} : TermElabM α := throwTypeMismatchError errorMsgHeader? expectedType eType e f?
let tryCoeSimple : TermElabM Expr :=
tryCoe errorMsgHeader? expectedType eType e f?
let some (n, β) ← isTypeApp? expectedType | tryCoeSimple
let tryPureCoeAndSimple : TermElabM Expr := do
if autoLift.get (← getOptions) then
match (← tryPureCoe? errorMsgHeader? n β eType e) with
| some eNew => pure eNew
| none => tryCoeSimple
else
tryCoeSimple
let some (m, α) ← isTypeApp? eType | tryPureCoeAndSimple
if (← isDefEq m n) then
let some monadInst ← isMonad? n | tryCoeSimple
try expandCoe (← mkAppOptM ``coeM #[m, α, β, none, monadInst, e]) catch _ => throwMismatch
else if autoLift.get (← getOptions) then
try
-- Construct lift from `m` to `n`
let monadLiftType ← mkAppM ``MonadLiftT #[m, n]
let monadLiftVal ← synthesizeInst monadLiftType
let u_1 ← getDecLevel α
let u_2 ← getDecLevel eType
let u_3 ← getDecLevel expectedType
let eNew := mkAppN (Lean.mkConst ``liftM [u_1, u_2, u_3]) #[m, n, monadLiftVal, α, e]
let eNewType ← inferType eNew
if (← isDefEq expectedType eNewType) then
return eNew -- approach 2 worked
else
let some monadInst ← isMonad? n | tryCoeSimple
let u ← getLevel α
let v ← getLevel β
let coeTInstType := Lean.mkForall `a BinderInfo.default α $ mkAppN (mkConst ``CoeT [u, v]) #[α, mkBVar 0, β]
let coeTInstVal ← synthesizeInst coeTInstType
let eNew ← expandCoe (← mkAppN (Lean.mkConst ``liftCoeM [u_1, u_2, u_3]) #[m, n, α, β, monadLiftVal, coeTInstVal, monadInst, e])
let eNewType ← inferType eNew
unless (← isDefEq expectedType eNewType) do throwMismatch
return eNew -- approach 3 worked
catch _ =>
/-
If `m` is not a monad, then we try to use `tryPureCoe?` and then `tryCoe?`.
Otherwise, we just try `tryCoe?`.
-/
match (← isMonad? m) with
| none => tryPureCoeAndSimple
| some _ => tryCoeSimple
else
tryCoeSimple
/--
If `expectedType?` is `some t`, then ensure `t` and `eType` are definitionally equal.
If they are not, then try coercions.
Argument `f?` is used only for generating error messages. -/
def ensureHasTypeAux (expectedType? : Option Expr) (eType : Expr) (e : Expr)
(f? : Option Expr := none) (errorMsgHeader? : Option String := none) : TermElabM Expr := do
match expectedType? with
| none => pure e
| some expectedType =>
if (← isDefEq eType expectedType) then
pure e
else
tryLiftAndCoe errorMsgHeader? expectedType eType e f?
/--
If `expectedType?` is `some t`, then ensure `t` and type of `e` are definitionally equal.
If they are not, then try coercions. -/
def ensureHasType (expectedType? : Option Expr) (e : Expr) (errorMsgHeader? : Option String := none) : TermElabM Expr :=
match expectedType? with
| none => pure e
| _ => do
let eType ← inferType e
ensureHasTypeAux expectedType? eType e none errorMsgHeader?
private def mkSyntheticSorryFor (expectedType? : Option Expr) : TermElabM Expr := do
let expectedType ← match expectedType? with
| none => mkFreshTypeMVar
| some expectedType => pure expectedType
mkSyntheticSorry expectedType
private def exceptionToSorry (ex : Exception) (expectedType? : Option Expr) : TermElabM Expr := do
let syntheticSorry ← mkSyntheticSorryFor expectedType?
logException ex
pure syntheticSorry
/-- If `mayPostpone == true`, throw `Expection.postpone`. -/
def tryPostpone : TermElabM Unit := do
if (← read).mayPostpone then
throwPostpone
/-- If `mayPostpone == true` and `e`'s head is a metavariable, throw `Exception.postpone`. -/
def tryPostponeIfMVar (e : Expr) : TermElabM Unit := do
if e.getAppFn.isMVar then
let e ← instantiateMVars e
if e.getAppFn.isMVar then
tryPostpone
def tryPostponeIfNoneOrMVar (e? : Option Expr) : TermElabM Unit :=
match e? with
| some e => tryPostponeIfMVar e
| none => tryPostpone
def tryPostponeIfHasMVars (expectedType? : Option Expr) (msg : String) : TermElabM Expr := do
tryPostponeIfNoneOrMVar expectedType?
let some expectedType ← pure expectedType? |
throwError "{msg}, expected type must be known"
let expectedType ← instantiateMVars expectedType
if expectedType.hasExprMVar then
tryPostpone
throwError "{msg}, expected type contains metavariables{indentExpr expectedType}"
pure expectedType
def saveContext : TermElabM SavedContext :=
return {
macroStack := (← read).macroStack
declName? := (← read).declName?
options := (← getOptions)
openDecls := (← getOpenDecls)
errToSorry := (← read).errToSorry
}
def withSavedContext (savedCtx : SavedContext) (x : TermElabM α) : TermElabM α := do
withReader (fun ctx => { ctx with declName? := savedCtx.declName?, macroStack := savedCtx.macroStack, errToSorry := savedCtx.errToSorry }) <|
withTheReader Core.Context (fun ctx => { ctx with options := savedCtx.options, openDecls := savedCtx.openDecls })
x
private def postponeElabTerm (stx : Syntax) (expectedType? : Option Expr) : TermElabM Expr := do
trace[Elab.postpone] "{stx} : {expectedType?}"
let mvar ← mkFreshExprMVar expectedType? MetavarKind.syntheticOpaque
let ctx ← read
registerSyntheticMVar stx mvar.mvarId! (SyntheticMVarKind.postponed (← saveContext))
pure mvar
def getSyntheticMVarDecl? (mvarId : MVarId) : TermElabM (Option SyntheticMVarDecl) :=
return (← get).syntheticMVars.find? fun d => d.mvarId == mvarId
/--
Create an auxiliary annotation to make sure we create a `Info` even if `e` is a metavariable.
See `mkTermInfo`.
We use this functions because some elaboration functions elaborate subterms that may not be immediately
part of the resulting term. Example:
```
let_mvar% ?m := b; wait_if_type_mvar% ?m; body
```
If the type of `b` is not known, then `wait_if_type_mvar% ?m; body` is postponed and just return a fresh
metavariable `?n`. The elaborator for
```
let_mvar% ?m := b; wait_if_type_mvar% ?m; body
```
returns `mkSaveInfoAnnotation ?n` to make sure the info nodes created when elaborating `b` are "saved".
This is a bit hackish, but elaborators like `let_mvar%` are rare.
-/
def mkSaveInfoAnnotation (e : Expr) : Expr :=
if e.isMVar then
mkAnnotation `save_info e
else
e
def isSaveInfoAnnotation? (e : Expr) : Option Expr :=
annotation? `save_info e
partial def removeSaveInfoAnnotation (e : Expr) : Expr :=
match isSaveInfoAnnotation? e with
| some e => removeSaveInfoAnnotation e
| _ => e
def mkTermInfo (elaborator : Name) (stx : Syntax) (e : Expr) (expectedType? : Option Expr := none) (lctx? : Option LocalContext := none) (isBinder := false) : TermElabM (Sum Info MVarId) := do
let isHole? : TermElabM (Option MVarId) := do
match e with
| Expr.mvar mvarId _ =>
match (← getSyntheticMVarDecl? mvarId) with
| some { kind := SyntheticMVarKind.tactic .., .. } => return mvarId
| some { kind := SyntheticMVarKind.postponed .., .. } => return mvarId
| _ => return none
| _ => pure none
match (← isHole?) with
| some mvarId => return Sum.inr mvarId
| none =>
let e := removeSaveInfoAnnotation e
return Sum.inl <| Info.ofTermInfo { elaborator, lctx := lctx?.getD (← getLCtx), expr := e, stx, expectedType?, isBinder }
def addTermInfo (stx : Syntax) (e : Expr) (expectedType? : Option Expr := none) (lctx? : Option LocalContext := none) (elaborator := Name.anonymous) (isBinder := false) : TermElabM Unit := do
withInfoContext' (pure ()) (fun _ => mkTermInfo elaborator stx e expectedType? lctx? isBinder) |> discard
/-
Helper function for `elabTerm` is tries the registered elaboration functions for `stxNode` kind until it finds one that supports the syntax or
an error is found. -/
private def elabUsingElabFnsAux (s : SavedState) (stx : Syntax) (expectedType? : Option Expr) (catchExPostpone : Bool)
: List (KeyedDeclsAttribute.AttributeEntry TermElab) → TermElabM Expr
| [] => do throwError "unexpected syntax{indentD stx}"
| (elabFn::elabFns) =>
try
-- record elaborator in info tree, but only when not backtracking to other elaborators (outer `try`)
withInfoContext' (mkInfo := mkTermInfo elabFn.declName (expectedType? := expectedType?) stx)
(try
elabFn.value stx expectedType?
catch ex => match ex with
| Exception.error ref msg =>
if (← read).errToSorry then
exceptionToSorry ex expectedType?
else
throw ex
| Exception.internal id _ =>
if (← read).errToSorry && id == abortTermExceptionId then
exceptionToSorry ex expectedType?
else if id == unsupportedSyntaxExceptionId then
throw ex -- to outer try
else if catchExPostpone && id == postponeExceptionId then
/- If `elab` threw `Exception.postpone`, we reset any state modifications.
For example, we want to make sure pending synthetic metavariables created by `elab` before
it threw `Exception.postpone` are discarded.
Note that we are also discarding the messages created by `elab`.
For example, consider the expression.
`((f.x a1).x a2).x a3`
Now, suppose the elaboration of `f.x a1` produces an `Exception.postpone`.
Then, a new metavariable `?m` is created. Then, `?m.x a2` also throws `Exception.postpone`
because the type of `?m` is not yet known. Then another, metavariable `?n` is created, and
finally `?n.x a3` also throws `Exception.postpone`. If we did not restore the state, we would
keep "dead" metavariables `?m` and `?n` on the pending synthetic metavariable list. This is
wasteful because when we resume the elaboration of `((f.x a1).x a2).x a3`, we start it from scratch
and new metavariables are created for the nested functions. -/
s.restore
postponeElabTerm stx expectedType?
else
throw ex)
catch ex => match ex with
| Exception.internal id _ =>
if id == unsupportedSyntaxExceptionId then
s.restore -- also removes the info tree created above
elabUsingElabFnsAux s stx expectedType? catchExPostpone elabFns
else
throw ex
| _ => throw ex
private def elabUsingElabFns (stx : Syntax) (expectedType? : Option Expr) (catchExPostpone : Bool) : TermElabM Expr := do
let s ← saveState
let k := stx.getKind
match termElabAttribute.getEntries (← getEnv) k with
| [] => throwError "elaboration function for '{k}' has not been implemented{indentD stx}"
| elabFns => elabUsingElabFnsAux s stx expectedType? catchExPostpone elabFns
instance : MonadMacroAdapter TermElabM where
getCurrMacroScope := getCurrMacroScope
getNextMacroScope := return (← getThe Core.State).nextMacroScope
setNextMacroScope next := modifyThe Core.State fun s => { s with nextMacroScope := next }
private def isExplicit (stx : Syntax) : Bool :=
match stx with
| `(@$f) => true
| _ => false
private def isExplicitApp (stx : Syntax) : Bool :=
stx.getKind == ``Lean.Parser.Term.app && isExplicit stx[0]
/--
Return true if `stx` if a lambda abstraction containing a `{}` or `[]` binder annotation.
Example: `fun {α} (a : α) => a` -/
private def isLambdaWithImplicit (stx : Syntax) : Bool :=
match stx with
| `(fun $binders* => $body) => binders.any fun b => b.isOfKind ``Lean.Parser.Term.implicitBinder || b.isOfKind `Lean.Parser.Term.instBinder
| _ => false
private partial def dropTermParens : Syntax → Syntax := fun stx =>
match stx with
| `(($stx)) => dropTermParens stx
| _ => stx
private def isHole (stx : Syntax) : Bool :=
match stx with
| `(_) => true
| `(? _) => true
| `(? $x:ident) => true
| _ => false
private def isTacticBlock (stx : Syntax) : Bool :=
match stx with
| `(by $x:tacticSeq) => true
| _ => false
private def isNoImplicitLambda (stx : Syntax) : Bool :=
match stx with
| `(no_implicit_lambda% $x:term) => true
| _ => false
private def isTypeAscription (stx : Syntax) : Bool :=
match stx with
| `(($e : $type)) => true
| _ => false
def mkNoImplicitLambdaAnnotation (type : Expr) : Expr :=
mkAnnotation `noImplicitLambda type
def hasNoImplicitLambdaAnnotation (type : Expr) : Bool :=
annotation? `noImplicitLambda type |>.isSome
/-- Block usage of implicit lambdas if `stx` is `@f` or `@f arg1 ...` or `fun` with an implicit binder annotation. -/
def blockImplicitLambda (stx : Syntax) : Bool :=
let stx := dropTermParens stx
-- TODO: make it extensible
isExplicit stx || isExplicitApp stx || isLambdaWithImplicit stx || isHole stx || isTacticBlock stx ||
isNoImplicitLambda stx || isTypeAscription stx
/--
Return normalized expected type if it is of the form `{a : α} → β` or `[a : α] → β` and
`blockImplicitLambda stx` is not true, else return `none`.
Remark: implicit lambdas are not triggered by the strict implicit binder annotation `{{a : α}} → β`
-/
private def useImplicitLambda? (stx : Syntax) (expectedType? : Option Expr) : TermElabM (Option Expr) :=
if blockImplicitLambda stx then
return none
else match expectedType? with
| some expectedType => do
if hasNoImplicitLambdaAnnotation expectedType then
return none
else
let expectedType ← whnfForall expectedType
match expectedType with
| Expr.forallE _ _ _ c =>
if c.binderInfo.isImplicit || c.binderInfo.isInstImplicit then
return some expectedType
else
return none
| _ => return none
| _ => return none
private def decorateErrorMessageWithLambdaImplicitVars (ex : Exception) (impFVars : Array Expr) : TermElabM Exception := do
match ex with
| Exception.error ref msg =>
if impFVars.isEmpty then
return Exception.error ref msg
else
let mut msg := m!"{msg}\nthe following variables have been introduced by the implicit lamda feature"
for impFVar in impFVars do
let auxMsg := m!"{impFVar} : {← inferType impFVar}"
let auxMsg ← addMessageContext auxMsg
msg := m!"{msg}{indentD auxMsg}"
msg := m!"{msg}\nyou can disable implict lambdas using `@` or writing a lambda expression with `\{}` or `[]` binder annotations."
return Exception.error ref msg
| _ => return ex
private def elabImplicitLambdaAux (stx : Syntax) (catchExPostpone : Bool) (expectedType : Expr) (impFVars : Array Expr) : TermElabM Expr := do
let body ← elabUsingElabFns stx expectedType catchExPostpone
try
let body ← ensureHasType expectedType body
let r ← mkLambdaFVars impFVars body
trace[Elab.implicitForall] r
pure r
catch ex =>
throw (← decorateErrorMessageWithLambdaImplicitVars ex impFVars)
private partial def elabImplicitLambda (stx : Syntax) (catchExPostpone : Bool) (type : Expr) : TermElabM Expr :=
loop type #[]
where
loop
| type@(Expr.forallE n d b c), fvars =>
if c.binderInfo.isExplicit then
elabImplicitLambdaAux stx catchExPostpone type fvars
else withFreshMacroScope do
let n ← MonadQuotation.addMacroScope n
withLocalDecl n c.binderInfo d fun fvar => do
let type ← whnfForall (b.instantiate1 fvar)
loop type (fvars.push fvar)
| type, fvars =>
elabImplicitLambdaAux stx catchExPostpone type fvars
/- Main loop for `elabTerm` -/
private partial def elabTermAux (expectedType? : Option Expr) (catchExPostpone : Bool) (implicitLambda : Bool) : Syntax → TermElabM Expr
| Syntax.missing => mkSyntheticSorryFor expectedType?
| stx => withFreshMacroScope <| withIncRecDepth do
trace[Elab.step] "expected type: {expectedType?}, term\n{stx}"
checkMaxHeartbeats "elaborator"
withNestedTraces do
let env ← getEnv
match (← liftMacroM (expandMacroImpl? env stx)) with
| some (decl, Except.ok stxNew) =>
withInfoContext' (mkInfo := mkTermInfo decl (expectedType? := expectedType?) stx) <|
withMacroExpansion stx stxNew <|
withRef stxNew <|
elabTermAux expectedType? catchExPostpone implicitLambda stxNew
| _ =>
let implicit? ← if implicitLambda && (← read).implicitLambda then useImplicitLambda? stx expectedType? else pure none
match implicit? with
| some expectedType => elabImplicitLambda stx catchExPostpone expectedType
| none => elabUsingElabFns stx expectedType? catchExPostpone
/-- Store in the `InfoTree` that `e` is a "dot"-completion target. -/
def addDotCompletionInfo (stx : Syntax) (e : Expr) (expectedType? : Option Expr) (field? : Option Syntax := none) : TermElabM Unit := do
addCompletionInfo <| CompletionInfo.dot { expr := e, stx, lctx := (← getLCtx), elaborator := Name.anonymous, expectedType? } (field? := field?) (expectedType? := expectedType?)
/--
Main function for elaborating terms.
It extracts the elaboration methods from the environment using the node kind.
Recall that the environment has a mapping from `SyntaxNodeKind` to `TermElab` methods.
It creates a fresh macro scope for executing the elaboration method.
All unlogged trace messages produced by the elaboration method are logged using
the position information at `stx`. If the elaboration method throws an `Exception.error` and `errToSorry == true`,
the error is logged and a synthetic sorry expression is returned.
If the elaboration throws `Exception.postpone` and `catchExPostpone == true`,
a new synthetic metavariable of kind `SyntheticMVarKind.postponed` is created, registered,
and returned.
The option `catchExPostpone == false` is used to implement `resumeElabTerm`
to prevent the creation of another synthetic metavariable when resuming the elaboration.
If `implicitLambda == true`, then disable implicit lambdas feature for the given syntax, but not for its subterms.
We use this flag to implement, for example, the `@` modifier. If `Context.implicitLambda == false`, then this parameter has no effect.
-/
def elabTerm (stx : Syntax) (expectedType? : Option Expr) (catchExPostpone := true) (implicitLambda := true) : TermElabM Expr :=
withRef stx <| elabTermAux expectedType? catchExPostpone implicitLambda stx
def elabTermEnsuringType (stx : Syntax) (expectedType? : Option Expr) (catchExPostpone := true) (implicitLambda := true) (errorMsgHeader? : Option String := none) : TermElabM Expr := do
let e ← elabTerm stx expectedType? catchExPostpone implicitLambda
withRef stx <| ensureHasType expectedType? e errorMsgHeader?
/--
Execute `x` and then restore `syntheticMVars`, `levelNames`, `mvarErrorInfos`, and `letRecsToLift`.
We use this combinator when we don't want the pending problems created by `x` to persist after its execution. -/
def withoutPending (x : TermElabM α) : TermElabM α := do
let saved ← get
try
x
finally
modify fun s => { s with syntheticMVars := saved.syntheticMVars, levelNames := saved.levelNames,
letRecsToLift := saved.letRecsToLift, mvarErrorInfos := saved.mvarErrorInfos }
/-- Execute `x` and return `some` if no new errors were recorded or exceptions was thrown. Otherwise, return `none` -/
def commitIfNoErrors? (x : TermElabM α) : TermElabM (Option α) := do
let saved ← saveState
modify fun s => { s with messages := {} }
try
let a ← x
if (← get).messages.hasErrors then
restoreState saved
return none
else
modify fun s => { s with messages := saved.elab.messages ++ s.messages }
return a
catch _ =>
restoreState saved
return none
/-- Adapt a syntax transformation to a regular, term-producing elaborator. -/
def adaptExpander (exp : Syntax → TermElabM Syntax) : TermElab := fun stx expectedType? => do
let stx' ← exp stx
withMacroExpansion stx stx' $ elabTerm stx' expectedType?
def mkInstMVar (type : Expr) : TermElabM Expr := do
let mvar ← mkFreshExprMVar type MetavarKind.synthetic
let mvarId := mvar.mvarId!
unless (← synthesizeInstMVarCore mvarId) do
registerSyntheticMVarWithCurrRef mvarId SyntheticMVarKind.typeClass
pure mvar
/-
Relevant definitions:
```
class CoeSort (α : Sort u) (β : outParam (Sort v))
abbrev coeSort {α : Sort u} {β : Sort v} (a : α) [CoeSort α β] : β
```
-/
private def tryCoeSort (α : Expr) (a : Expr) : TermElabM Expr := do
let β ← mkFreshTypeMVar
let u ← getLevel α
let v ← getLevel β
let coeSortInstType := mkAppN (Lean.mkConst ``CoeSort [u, v]) #[α, β]
let mvar ← mkFreshExprMVar coeSortInstType MetavarKind.synthetic
let mvarId := mvar.mvarId!
try
withoutMacroStackAtErr do
if (← synthesizeCoeInstMVarCore mvarId) then
let result ← expandCoe <| mkAppN (Lean.mkConst ``coeSort [u, v]) #[α, β, a, mvar]
unless (← isType result) do
throwError "failed to coerse{indentExpr a}\nto a type, after applying `coeSort`, result is still not a type{indentExpr result}\nthis is often due to incorrect `CoeSort` instances, the synthesized value for{indentExpr coeSortInstType}\nwas{indentExpr mvar}"
return result
else
throwError "type expected"
catch
| Exception.error _ msg => throwError "type expected\n{msg}"
| _ => throwError "type expected"
/--
Make sure `e` is a type by inferring its type and making sure it is a `Expr.sort`
or is unifiable with `Expr.sort`, or can be coerced into one. -/
def ensureType (e : Expr) : TermElabM Expr := do
if (← isType e) then
pure e
else
let eType ← inferType e
let u ← mkFreshLevelMVar
if (← isDefEq eType (mkSort u)) then
pure e
else
tryCoeSort eType e
/-- Elaborate `stx` and ensure result is a type. -/
def elabType (stx : Syntax) : TermElabM Expr := do
let u ← mkFreshLevelMVar
let type ← elabTerm stx (mkSort u)
withRef stx $ ensureType type
/--
Enable auto-bound implicits, and execute `k` while catching auto bound implicit exceptions. When an exception is caught,
a new local declaration is created, registered, and `k` is tried to be executed again. -/
partial def withAutoBoundImplicit (k : TermElabM α) : TermElabM α := do
let flag := autoBoundImplicitLocal.get (← getOptions)
if flag then
withReader (fun ctx => { ctx with autoBoundImplicit := flag, autoBoundImplicits := {} }) do
let rec loop (s : SavedState) : TermElabM α := do
try
k
catch
| ex => match isAutoBoundImplicitLocalException? ex with
| some n =>
-- Restore state, declare `n`, and try again
s.restore
withLocalDecl n BinderInfo.implicit (← mkFreshTypeMVar) fun x =>
withReader (fun ctx => { ctx with autoBoundImplicits := ctx.autoBoundImplicits.push x } ) do
loop (← saveState)
| none => throw ex
loop (← saveState)
else
k
def withoutAutoBoundImplicit (k : TermElabM α) : TermElabM α := do
withReader (fun ctx => { ctx with autoBoundImplicit := false, autoBoundImplicits := {} }) k
/--
Return `autoBoundImplicits ++ xs.
This methoid throws an error if a variable in `autoBoundImplicits` depends on some `x` in `xs` -/
def addAutoBoundImplicits (xs : Array Expr) : TermElabM (Array Expr) := do
let autoBoundImplicits := (← read).autoBoundImplicits
for auto in autoBoundImplicits do
let localDecl ← getLocalDecl auto.fvarId!
for x in xs do
if (← getMCtx).localDeclDependsOn localDecl x.fvarId! then
throwError "invalid auto implicit argument '{auto}', it depends on explicitly provided argument '{x}'"
return autoBoundImplicits.toArray ++ xs
def mkAuxName (suffix : Name) : TermElabM Name := do
match (← read).declName? with
| none => throwError "auxiliary declaration cannot be created when declaration name is not available"
| some declName => Lean.mkAuxName (declName ++ suffix) 1
builtin_initialize registerTraceClass `Elab.letrec
/- Return true if mvarId is an auxiliary metavariable created for compiling `let rec` or it
is delayed assigned to one. -/
def isLetRecAuxMVar (mvarId : MVarId) : TermElabM Bool := do
trace[Elab.letrec] "mvarId: {mkMVar mvarId} letrecMVars: {(← get).letRecsToLift.map (mkMVar $ ·.mvarId)}"
let mvarId := (← getMCtx).getDelayedRoot mvarId
trace[Elab.letrec] "mvarId root: {mkMVar mvarId}"
return (← get).letRecsToLift.any (·.mvarId == mvarId)
def resolveLocalName (n : Name) : TermElabM (Option (Expr × List String)) := do
let lctx ← getLCtx
let view := extractMacroScopes n
let rec loop (n : Name) (projs : List String) :=
match lctx.findFromUserName? { view with name := n }.review with
| some decl =>
if decl.isAuxDecl && !projs.isEmpty then
/- We do not consider dot notation for local decls corresponding to recursive functions being defined.
The following example would not be elaborated correctly without this case.
```
def foo.aux := 1
def foo : Nat → Nat
| n => foo.aux -- should not be interpreted as `(foo).bar`
```
-/
none
else
some (decl.toExpr, projs)
| none => match n with
| Name.str pre s _ => loop pre (s::projs)
| _ => none
return loop view.name []
/- Return true iff `stx` is a `Syntax.ident`, and it is a local variable. -/
def isLocalIdent? (stx : Syntax) : TermElabM (Option Expr) :=
match stx with
| Syntax.ident _ _ val _ => do
let r? ← resolveLocalName val
match r? with
| some (fvar, []) => pure (some fvar)
| _ => pure none
| _ => pure none
/--
Create an `Expr.const` using the given name and explicit levels.
Remark: fresh universe metavariables are created if the constant has more universe
parameters than `explicitLevels`. -/
def mkConst (constName : Name) (explicitLevels : List Level := []) : TermElabM Expr := do
let cinfo ← getConstInfo constName
if explicitLevels.length > cinfo.levelParams.length then
throwError "too many explicit universe levels for '{constName}'"
else
let numMissingLevels := cinfo.levelParams.length - explicitLevels.length
let us ← mkFreshLevelMVars numMissingLevels
return Lean.mkConst constName (explicitLevels ++ us)
private def mkConsts (candidates : List (Name × List String)) (explicitLevels : List Level) : TermElabM (List (Expr × List String)) := do
candidates.foldlM (init := []) fun result (constName, projs) => do
-- TODO: better suppor for `mkConst` failure. We may want to cache the failures, and report them if all candidates fail.
let const ← mkConst constName explicitLevels
return (const, projs) :: result
def resolveName (stx : Syntax) (n : Name) (preresolved : List (Name × List String)) (explicitLevels : List Level) (expectedType? : Option Expr := none) : TermElabM (List (Expr × List String)) := do
try
if let some (e, projs) ← resolveLocalName n then
unless explicitLevels.isEmpty do
throwError "invalid use of explicit universe parameters, '{e}' is a local"
return [(e, projs)]
-- check for section variable capture by a quotation
let ctx ← read
if let some (e, projs) := preresolved.findSome? fun (n, projs) => ctx.sectionFVars.find? n |>.map (·, projs) then
return [(e, projs)] -- section variables should shadow global decls
if preresolved.isEmpty then
process (← resolveGlobalName n)
else
process preresolved
catch ex =>
if preresolved.isEmpty && explicitLevels.isEmpty then
addCompletionInfo <| CompletionInfo.id stx stx.getId (danglingDot := false) (← getLCtx) expectedType?
throw ex
where process (candidates : List (Name × List String)) : TermElabM (List (Expr × List String)) := do
if candidates.isEmpty then
if (← read).autoBoundImplicit && isValidAutoBoundImplicitName n then
throwAutoBoundImplicitLocal n
else
throwError "unknown identifier '{Lean.mkConst n}'"
if preresolved.isEmpty && explicitLevels.isEmpty then
addCompletionInfo <| CompletionInfo.id stx stx.getId (danglingDot := false) (← getLCtx) expectedType?
mkConsts candidates explicitLevels
/--
Similar to `resolveName`, but creates identifiers for the main part and each projection with position information derived from `ident`.
Example: Assume resolveName `v.head.bla.boo` produces `(v.head, ["bla", "boo"])`, then this method produces
`(v.head, id, [f₁, f₂])` where `id` is an identifier for `v.head`, and `f₁` and `f₂` are identifiers for fields `"bla"` and `"boo"`. -/
def resolveName' (ident : Syntax) (explicitLevels : List Level) (expectedType? : Option Expr := none) : TermElabM (List (Expr × Syntax × List Syntax)) := do
match ident with
| Syntax.ident info rawStr n preresolved =>
let r ← resolveName ident n preresolved explicitLevels expectedType?
r.mapM fun (c, fields) => do
let ids := ident.identComponents (nFields? := fields.length)
return (c, ids.head!, ids.tail!)
| _ => throwError "identifier expected"
def resolveId? (stx : Syntax) (kind := "term") (withInfo := false) : TermElabM (Option Expr) :=
match stx with
| Syntax.ident _ _ val preresolved => do
let rs ← try resolveName stx val preresolved [] catch _ => pure []
let rs := rs.filter fun ⟨f, projs⟩ => projs.isEmpty
let fs := rs.map fun (f, _) => f
match fs with
| [] => pure none
| [f] =>
if withInfo then
addTermInfo stx f
pure (some f)
| _ => throwError "ambiguous {kind}, use fully qualified name, possible interpretations {fs}"
| _ => throwError "identifier expected"
private def mkSomeContext : Context := {
fileName := "<TermElabM>"
fileMap := arbitrary
}
def TermElabM.run (x : TermElabM α) (ctx : Context := mkSomeContext) (s : State := {}) : MetaM (α × State) :=
withConfig setElabConfig (x ctx |>.run s)
@[inline] def TermElabM.run' (x : TermElabM α) (ctx : Context := mkSomeContext) (s : State := {}) : MetaM α :=
(·.1) <$> x.run ctx s
def TermElabM.toIO (x : TermElabM α)
(ctxCore : Core.Context) (sCore : Core.State)
(ctxMeta : Meta.Context) (sMeta : Meta.State)
(ctx : Context) (s : State) : IO (α × Core.State × Meta.State × State) := do
let ((a, s), sCore, sMeta) ← (x.run ctx s).toIO ctxCore sCore ctxMeta sMeta
pure (a, sCore, sMeta, s)
instance [MetaEval α] : MetaEval (TermElabM α) where
eval env opts x _ :=
let x : TermElabM α := do
try x finally
let s ← get
s.messages.forM fun msg => do IO.println (← msg.toString)
MetaEval.eval env opts (hideUnit := true) $ x.run' mkSomeContext
unsafe def evalExpr (α) (typeName : Name) (value : Expr) : TermElabM α :=
withoutModifyingEnv do
let name ← mkFreshUserName `_tmp
let type ← inferType value
let type ← whnfD type
unless type.isConstOf typeName do
throwError "unexpected type at evalExpr{indentExpr type}"
let decl := Declaration.defnDecl {
name := name, levelParams := [], type := type,
value := value, hints := ReducibilityHints.opaque,
safety := DefinitionSafety.unsafe
}
ensureNoUnassignedMVars decl
addAndCompile decl
evalConst α name
private def throwStuckAtUniverseCnstr : TermElabM Unit := do
-- This code assumes `entries` is not empty. Note that `processPostponed` uses `exceptionOnFailure` to guarantee this property
let entries ← getPostponed
let mut found : Std.HashSet (Level × Level) := {}
let mut uniqueEntries := #[]
for entry in entries do
let mut lhs := entry.lhs
let mut rhs := entry.rhs
if Level.normLt rhs lhs then
(lhs, rhs) := (rhs, lhs)
unless found.contains (lhs, rhs) do
found := found.insert (lhs, rhs)
uniqueEntries := uniqueEntries.push entry
for i in [1:uniqueEntries.size] do
logErrorAt uniqueEntries[i].ref (← mkLevelStuckErrorMessage uniqueEntries[i])
throwErrorAt uniqueEntries[0].ref (← mkLevelStuckErrorMessage uniqueEntries[0])
def withoutPostponingUniverseConstraints (x : TermElabM α) : TermElabM α := do
let postponed ← getResetPostponed
try
let a ← x
unless (← processPostponed (mayPostpone := false) (exceptionOnFailure := true)) do
throwStuckAtUniverseCnstr
setPostponed postponed
return a
catch ex =>
setPostponed postponed
throw ex
end Term
open Term in
def withoutModifyingStateWithInfoAndMessages [MonadControlT TermElabM m] [Monad m] (x : m α) : m α := do
controlAt TermElabM fun runInBase => withoutModifyingStateWithInfoAndMessagesImpl <| runInBase x
builtin_initialize
registerTraceClass `Elab.postpone
registerTraceClass `Elab.coe
registerTraceClass `Elab.debug
export Term (TermElabM)
end Lean.Elab
|
aed3f441ef6a72549401bae55ed50eda64d5172e | a9e33f9c83301c461f3c3ebc6799d9de1f6d4d20 | /assignments/hw3_function_terms_lambda.lean | ca371add113c6e48ab05a751f13dad0a91db5d38 | [] | no_license | yl4df/Discrete-Mathematics | f1c9a6cf8cfb4686fb617637f69a481e1522f0c2 | c93ce9f6a6e36d194e350d9fa0a0360191e97fa0 | refs/heads/master | 1,598,714,938,443 | 1,572,275,647,000 | 1,572,275,647,000 | 218,074,726 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 7,031 | lean | -- You can ignore this line for now, but don't remove it.
namespace hw3
/-
In this assignment, you will put into practice your new
knowledge of terms and definitions in predicate logic by
using it to implement a library of Boolean functions. You
will also gain practice using different forms of syntax
for defining functions.
-/
/-
To begin, we present one "unary" Boolean function (taking
one Boolean argument and returning a Boolean result) and one
"binary" function (taking two arguments), using each of three
styles of syntax.
-/
/-
First, here are three implementations of exactly the
same unary function, namely negation, in three styles.
-/
-- explicitly lambda expression
def neg_bool : bool → bool :=
λ (b : bool),
match b with
| ff := tt
| tt := ff
end
-- by cases; note absence of := after function type
def neg_bool' : bool → bool
| ff := tt
| tt := ff
-- C-style; note return type is now between : and :=
def neg_bool'' (b : bool) : bool :=
match b with
| ff := tt
| tt := ff
end
/-
Second, here are three implementations of exactly the
same binary function (Boolean "and"), in the same three
styles.
-/
-- Note commas in match expression and in each case
def and_bool : bool → bool → bool :=
λ (b1 b2 : bool), --shorthand for two lambdas
match b1, b2 with -- matching on two arguments
| ff, ff := ff
| ff, tt := ff
| tt, ff := ff
| tt, tt := tt
end
-- Note absence of := and of commas in each of the cases
def and_bool' : bool → bool → bool
| ff ff := ff
| ff tt := ff
| tt ff := ff
| tt tt := tt
-- should seem straightforward now
def and_bool'' (b1 b2 : bool) : bool :=
match b1, b2 with
| ff, ff := ff
| ff, tt := ff
| tt, ff := ff
| tt, tt := tt
end
/-
Your homework is to implement the remaining unary Boolean
functions, and several key binary Boolean functions, each
one in each of these styles: lambda, by-cases, and C-style.
-/
/-
1. Implement the always false unary Boolean function in each
of the three styles, lambda, by-cases, and C-style. Call the
functions false_bool, false_bool', and false_bool'', in that
order.
-/
-- Here's the first one, just to get you going.
def false_bool : bool → bool :=
λ (b : bool),
ff
-- Now false_bool'
def false_bool' : bool → bool
| tt := ff
| ff := ff
-- And now false_bool''
def false_bool'' (b:bool) : bool :=
match b with
| ff := ff
| tt := ff
end
/-
2. Do the same for the always true unary Boolean function,
using true_bool as the function name (with zero, one, and
two ' marks to avoid name conflicts. You will use ' in this
way for each of the remaining parts of this assignment).
-/
def true_bool : bool → bool :=
λ (b : bool),
tt
def true_bool' : bool → bool
| tt := tt
| ff := tt
def true_bool'' (b:bool) : bool :=
match b with
| ff := tt
| tt := tt
end
/-
3. Do the same for the unary Boolean identity function,
using ident_bool (and ' variants) as the function name.
-/
def ident_bool : bool → bool :=
λ (b : bool),
match b with
| ff := ff
| tt := tt
end
def ident_bool' : bool → bool
| tt := tt
| ff := ff
def ident_bool'' (b:bool) : bool :=
match b with
| ff := ff
| tt := tt
end
/-
Congrats, you now have a small library of all unary Boolean
functions. Now turn to the binary functions. Each will take
two Boolean arguments, we can call them b1 and b2, and will
return a Boolean result.
-/
/-
4. The Boolean "or" function is true if and only if at least
one of b1 and b2 is true. Equivalently it is false if and only
if both b1 and b2 are false. Implement this function in each
of the three styles, using or_bool as the function name. You
may use the example of "and_bool" above as a model. While you
could just cut and paste, we strongly recommend that you type
your answers in full. Learning new syntax is an exercise is
"muscle memory", so don't take shortcuts here. Learn the
syntax now and it will save you frustration later.
-/
def or_bool : bool → bool → bool :=
λ (b1 b2 : bool),
match b1, b2 with
|ff, ff := ff
|ff, tt := tt
|tt, ff := tt
|tt, tt := tt
end
def or_bool' : bool → bool → bool
|ff ff := ff
|ff tt := tt
|tt ff := tt
|tt tt := tt
def or_bool'' (b1 b2 : bool) : bool :=
match b1, b2 with
|ff, ff := ff
|ff, tt := tt
|tt, ff := tt
|tt, tt := tt
end
/-
5. The Boolean "exclusive or" function is true if and only if
exactly one of its arguments is true. Implement this function
in each style using xor_bool as the function name.
-/
def xor_bool : bool → bool → bool :=
λ (b1 b2 : bool),
match b1, b2 with
|ff, ff := ff
|ff, tt := tt
|tt, ff := tt
|tt, tt := ff
end
def xor_bool' : bool → bool → bool
|ff ff := ff
|ff tt := tt
|tt ff := tt
|tt tt := ff
def xor_bool'' (b1 b2 : bool) : bool :=
match b1, b2 with
|ff, ff := ff
|ff, tt := tt
|tt, ff := tt
|tt, tt := ff
end
/-
6. The Boolean "implies" function is true if and only if
either its first argument is false, or its first argument is
true and its second argument is also true. Equivalently it is
false if and only if its first argument is true and its second is false. Implement it in each style, calling it implies_bool.
-/
def implies_bool : bool → bool → bool :=
λ (b1 b2 : bool),
match b1, b2 with
|ff, ff := tt
|ff, tt := tt
|tt, ff := ff
|tt, tt := tt
end
def implies_bool' : bool → bool → bool
|ff ff := tt
|ff tt := tt
|tt ff := ff
|tt tt := tt
def implies_bool'' (b1 b2 : bool) : bool :=
match b1, b2 with
|ff, ff := tt
|ff, tt := tt
|tt, ff := ff
|tt, tt := tt
end
/-
7. The Boolean "equivalent-to" function is true if its two arguments are the same, either both true or both false;
otherwise it is false. Implement it in the three styles,
using equiv_bool as a function name.
-/
def equiv_bool : bool → bool → bool :=
λ (b1 b2 : bool),
match b1, b2 with
|ff, ff := tt
|ff, tt := ff
|tt, ff := ff
|tt, tt := tt
end
def equiv_bool' : bool → bool → bool
|ff ff := tt
|ff tt := ff
|tt ff := ff
|tt tt := tt
def equiv_bool'' (b1 b2 : bool) : bool :=
match b1, b2 with
|ff, ff := tt
|ff, tt := ff
|tt, ff := ff
|tt, tt := tt
end
-- leave the following in place as the last line in this file
end hw3
|
9a5c21877a74a099ab64ed21534bf023a1441652 | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/tactic/omega/coeffs.lean | 81fbe2f2848fcbe04129576a52e3722f816e25fd | [
"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 | 10,458 | lean | /-
Copyright (c) 2019 Seul Baek. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Seul Baek
-/
/-
Non-constant terms of linear constraints are represented
by storing their coefficients in integer lists.
-/
import data.list.func
import tactic.ring
import tactic.omega.misc
namespace omega
namespace coeffs
open list.func
variable {v : nat → int}
/-- `val_between v as l o` is the value (under valuation `v`) of the term
obtained taking the term represented by `(0, as)` and dropping all
subterms that include variables outside the range `[l,l+o)` -/
@[simp] def val_between (v : nat → int) (as : list int) (l : nat) : nat → int
| 0 := 0
| (o+1) := (val_between o) + (get (l+o) as * v (l+o))
@[simp] lemma val_between_nil {l : nat} :
∀ m, val_between v [] l m = 0
| 0 := by simp only [val_between]
| (m+1) :=
by simp only [val_between_nil m, omega.coeffs.val_between,
get_nil, zero_add, zero_mul, int.default_eq_zero]
/-- Evaluation of the nonconstant component of a normalized linear arithmetic term. -/
def val (v : nat → int) (as : list int) : int :=
val_between v as 0 as.length
@[simp] lemma val_nil : val v [] = 0 := rfl
lemma val_between_eq_of_le {as : list int} {l : nat} :
∀ m, as.length ≤ l + m →
val_between v as l m = val_between v as l (as.length - l)
| 0 h1 := by { rw add_zero at h1, rw tsub_eq_zero_iff_le.mpr h1 }
| (m+1) h1 :=
begin
rw le_iff_eq_or_lt at h1, cases h1,
{ rw [h1, add_comm l, add_tsub_cancel_right] },
have h2 : list.length as ≤ l + m,
{ rw ← nat.lt_succ_iff, apply h1 },
simpa [ get_eq_default_of_le _ h2, zero_mul, add_zero,
val_between ] using val_between_eq_of_le _ h2
end
lemma val_eq_of_le {as : list int} {k : nat} :
as.length ≤ k → val v as = val_between v as 0 k :=
begin
intro h1, unfold val,
rw [val_between_eq_of_le k _], refl,
rw zero_add, exact h1
end
lemma val_between_eq_val_between
{v w : nat → int} {as bs : list int} {l : nat} :
∀ {m}, (∀ x, l ≤ x → x < l + m → v x = w x) →
(∀ x, l ≤ x → x < l + m → get x as = get x bs) →
val_between v as l m = val_between w bs l m
| 0 h1 h2 := rfl
| (m+1) h1 h2 :=
begin
unfold val_between,
have h3 : l + m < l + (m + 1),
{ rw ← add_assoc, apply lt_add_one },
apply fun_mono_2,
apply val_between_eq_val_between; intros x h4 h5,
{ apply h1 _ h4 (lt_trans h5 h3) },
{ apply h2 _ h4 (lt_trans h5 h3) },
rw [h1 _ _ h3, h2 _ _ h3];
apply nat.le_add_right
end
open_locale list.func
lemma val_between_set {a : int} {l n : nat} :
∀ {m}, l ≤ n → n < l + m → val_between v ([] {n ↦ a}) l m = a * v n
| 0 h1 h2 :=
begin exfalso, apply lt_irrefl l (lt_of_le_of_lt h1 h2) end
| (m+1) h1 h2 :=
begin
rw [← add_assoc, nat.lt_succ_iff, le_iff_eq_or_lt] at h2,
cases h2; unfold val_between,
{ have h3 : val_between v ([] {l + m ↦ a}) l m = 0,
{ apply @eq.trans _ _ (val_between v [] l m),
{ apply val_between_eq_val_between,
{ intros, refl },
{ intros x h4 h5, rw [get_nil,
get_set_eq_of_ne, get_nil],
apply ne_of_lt h5 } },
apply val_between_nil },
rw h2,
simp only [h3, zero_add, list.func.get_set] },
{ have h3 : l + m ≠ n,
{ apply ne_of_gt h2 },
rw [@val_between_set m h1 h2, get_set_eq_of_ne _ _ h3],
simp only [h3, get_nil, add_zero, zero_mul, int.default_eq_zero] }
end
@[simp] lemma val_set {m : nat} {a : int} :
val v ([] {m ↦ a}) = a * v m :=
begin
apply val_between_set (zero_le _),
rw [length_set, zero_add],
exact lt_max_of_lt_right (lt_add_one _),
end
lemma val_between_neg {as : list int} {l : nat} :
∀ {o}, val_between v (neg as) l o = -(val_between v as l o)
| 0 := rfl
| (o+1) :=
begin
unfold val_between,
rw [neg_add, neg_mul_eq_neg_mul],
apply fun_mono_2,
apply val_between_neg,
apply fun_mono_2 _ rfl,
apply get_neg
end
@[simp] lemma val_neg {as : list int} :
val v (neg as) = -(val v as) :=
by simpa only [val, length_neg] using val_between_neg
lemma val_between_add {is js : list int} {l : nat} :
∀ m, val_between v (add is js) l m =
(val_between v is l m) + (val_between v js l m)
| 0 := rfl
| (m+1) :=
by { simp only [val_between, val_between_add m,
list.func.get, get_add], ring }
@[simp] lemma val_add {is js : list int} :
val v (add is js) = (val v is) + (val v js) :=
begin
unfold val,
rw val_between_add, apply fun_mono_2;
apply val_between_eq_of_le;
rw [zero_add, length_add],
apply le_max_left, apply le_max_right
end
lemma val_between_sub {is js : list int} {l : nat} :
∀ m, val_between v (sub is js) l m =
(val_between v is l m) - (val_between v js l m)
| 0 := rfl
| (m+1) :=
by { simp only [val_between, val_between_sub m,
list.func.get, get_sub], ring }
@[simp] lemma val_sub {is js : list int} :
val v (sub is js) = (val v is) - (val v js) :=
begin
unfold val,
rw val_between_sub,
apply fun_mono_2;
apply val_between_eq_of_le;
rw [zero_add, length_sub],
apply le_max_left,
apply le_max_right
end
/-- `val_except k v as` is the value (under valuation `v`) of the term
obtained taking the term represented by `(0, as)` and dropping the
subterm that includes the `k`th variable. -/
def val_except (k : nat) (v : nat → int) (as) :=
val_between v as 0 k + val_between v as (k+1) (as.length - (k+1))
lemma val_except_eq_val_except
{k : nat} {is js : list int} {v w : nat → int} :
(∀ x ≠ k, v x = w x) → (∀ x ≠ k, get x is = get x js) →
val_except k v is = val_except k w js :=
begin
intros h1 h2, unfold val_except,
apply fun_mono_2,
{ apply val_between_eq_val_between;
intros x h3 h4;
[ {apply h1}, {apply h2} ];
apply ne_of_lt;
rw zero_add at h4;
apply h4 },
{ repeat { rw ← val_between_eq_of_le
((max is.length js.length) - (k+1)) },
{ apply val_between_eq_val_between;
intros x h3 h4;
[ {apply h1}, {apply h2} ];
apply ne.symm;
apply ne_of_lt;
rw nat.lt_iff_add_one_le;
exact h3 },
{ refine le_trans (le_max_right _ _) le_add_tsub },
{ refine le_trans (le_max_left _ _) le_add_tsub } }
end
open_locale omega
lemma val_except_update_set
{n : nat} {as : list int} {i j : int} :
val_except n (v⟨n ↦ i⟩) (as {n ↦ j}) = val_except n v as :=
by apply val_except_eq_val_except update_eq_of_ne (get_set_eq_of_ne _)
lemma val_between_add_val_between {as : list int} {l m : nat} :
∀ {n}, val_between v as l m + val_between v as (l+m) n =
val_between v as l (m+n)
| 0 := by simp only [val_between, add_zero]
| (n+1) :=
begin
rw ← add_assoc,
unfold val_between,
rw add_assoc,
rw ← @val_between_add_val_between n,
ring,
end
lemma val_except_add_eq (n : nat) {as : list int} :
(val_except n v as) + ((get n as) * (v n)) = val v as :=
begin
unfold val_except, unfold val,
cases le_total (n + 1) as.length with h1 h1,
{ have h4 := @val_between_add_val_between v as 0 (n+1) (as.length - (n+1)),
have h5 : n + 1 + (as.length - (n + 1)) = as.length,
{ rw [add_comm, tsub_add_cancel_of_le h1] },
rw h5 at h4, apply eq.trans _ h4,
simp only [val_between, zero_add], ring },
have h2 : list.length as - (n + 1) = 0,
{ exact tsub_eq_zero_iff_le.mpr h1 },
have h3 : val_between v as 0 (list.length as) =
val_between v as 0 (n + 1),
{ simpa only [val] using @val_eq_of_le v as (n+1) h1 },
simp only [add_zero, val_between, zero_add, h2, h3]
end
@[simp] lemma val_between_map_mul {i : int} {as: list int} {l : nat} :
∀ {m}, val_between v (list.map ((*) i) as) l m = i * val_between v as l m
| 0 := by simp only [val_between, mul_zero, list.map]
| (m+1) :=
begin
unfold val_between,
rw [@val_between_map_mul m, mul_add],
apply fun_mono_2 rfl,
by_cases h1 : l + m < as.length,
{ rw [get_map h1, mul_assoc] },
rw not_lt at h1,
rw [get_eq_default_of_le, get_eq_default_of_le];
try {simp}; apply h1
end
lemma forall_val_dvd_of_forall_mem_dvd {i : int} {as : list int} :
(∀ x ∈ as, i ∣ x) → (∀ n, i ∣ get n as) | h1 n :=
by { apply forall_val_of_forall_mem _ h1,
apply dvd_zero }
lemma dvd_val_between {i} {as: list int} {l : nat} :
∀ {m}, (∀ x ∈ as, i ∣ x) → (i ∣ val_between v as l m)
| 0 h1 := dvd_zero _
| (m+1) h1 :=
begin
unfold val_between,
apply dvd_add,
apply dvd_val_between h1,
apply dvd_mul_of_dvd_left,
by_cases h2 : get (l+m) as = 0,
{ rw h2, apply dvd_zero },
apply h1, apply mem_get_of_ne_zero h2
end
lemma dvd_val {as : list int} {i : int} :
(∀ x ∈ as, i ∣ x) → (i ∣ val v as) := by apply dvd_val_between
@[simp] lemma val_between_map_div
{as: list int} {i : int} {l : nat} (h1 : ∀ x ∈ as, i ∣ x) :
∀ {m}, val_between v (list.map (λ x, x / i) as) l m = (val_between v as l m) / i
| 0 := by simp only [int.zero_div, val_between, list.map]
| (m+1) :=
begin
unfold val_between,
rw [@val_between_map_div m, int.add_div_of_dvd_right],
apply fun_mono_2 rfl,
{ apply calc get (l + m) (list.map (λ (x : ℤ), x / i) as) * v (l + m)
= ((get (l + m) as) / i) * v (l + m) :
begin
apply fun_mono_2 _ rfl,
rw get_map',
apply int.zero_div
end
... = get (l + m) as * v (l + m) / i :
begin
repeat {rw mul_comm _ (v (l+m))},
rw int.mul_div_assoc,
apply forall_val_dvd_of_forall_mem_dvd h1
end },
apply dvd_mul_of_dvd_left,
apply forall_val_dvd_of_forall_mem_dvd h1,
end
@[simp] lemma val_map_div {as : list int} {i : int} :
(∀ x ∈ as, i ∣ x) → val v (list.map (λ x, x / i) as) = (val v as) / i :=
by {intro h1, simpa only [val, list.length_map] using val_between_map_div h1}
lemma val_between_eq_zero {is: list int} {l : nat} :
∀ {m}, (∀ x : int, x ∈ is → x = 0) → val_between v is l m = 0
| 0 h1 := rfl
| (m+1) h1 :=
begin
have h2 := @forall_val_of_forall_mem _ _ is (λ x, x = 0) rfl h1,
simpa only [val_between, h2 (l+m), zero_mul, add_zero]
using @val_between_eq_zero m h1,
end
lemma val_eq_zero {is : list int} :
(∀ x : int, x ∈ is → x = 0) → val v is = 0 :=
by apply val_between_eq_zero
end coeffs
end omega
|
0b6c2c54652f066041410b99ac4556f8cf3e0159 | b7f22e51856f4989b970961f794f1c435f9b8f78 | /tests/lean/axioms_of.lean | 9adad7a53311a7383eb0907cd1bc3cebbc6c0b17 | [
"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 | 243 | lean | import data.finset data.rat
print axioms nat.add
print "-----"
print axioms int.add
print "-----"
print axioms rat.add
print "-----"
print axioms finset.union
print "-----"
print axioms finset.mem
print "-----"
print axioms finset.union_comm
|
9f9130799d88e61ff1f2d575c74de1c34003f6e3 | d1a52c3f208fa42c41df8278c3d280f075eb020c | /tests/compiler/str.lean | 69db1e35d5a0546d6d8d86f324a711c721071d68 | [
"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 | cipher1024/lean4 | 6e1f98bb58e7a92b28f5364eb38a14c8d0aae393 | 69114d3b50806264ef35b57394391c3e738a9822 | refs/heads/master | 1,642,227,983,603 | 1,642,011,696,000 | 1,642,011,696,000 | 228,607,691 | 0 | 0 | Apache-2.0 | 1,576,584,269,000 | 1,576,584,268,000 | null | UTF-8 | Lean | false | false | 937 | lean | def showChars : Nat → String → String.Pos → IO Unit
| 0, _, _ => pure ()
| n+1, s, idx => do
unless s.atEnd idx do
IO.println (">> " ++ toString (s.get idx)) *>
showChars n s (s.next idx)
def main : IO UInt32 :=
let s₁ := "hello α_world_β";
let b : String.Pos := 0;
let e := s₁.bsize;
IO.println (s₁.extract b e) *>
IO.println (s₁.extract (b+2) e) *>
IO.println (s₁.extract (b+2) (e-1)) *>
IO.println (s₁.extract (b+2) (e-2)) *>
IO.println (s₁.extract (b+7) e) *>
IO.println (s₁.extract (b+8) e) *>
IO.println (toString e) *>
IO.println (repr " aaa ".trim) *>
showChars s₁.length s₁ 0 *>
IO.println ("abc".isPrefixOf "abcd") *>
IO.println ("abcd".isPrefixOf "abcd") *>
IO.println ("".isPrefixOf "abcd") *>
IO.println ("".isPrefixOf "") *>
IO.println ("ab".isPrefixOf "cb") *>
IO.println ("ab".isPrefixOf "a") *>
IO.println ("αb".isPrefixOf "αbc") *>
pure 0
|
c2561b5b652c2d0c65a20e0d193055938c958e15 | 4d2583807a5ac6caaffd3d7a5f646d61ca85d532 | /src/order/closure.lean | b3b6e056750be5fd7442b8420583ecf36a92a96c | [
"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 | 17,374 | lean | /-
Copyright (c) 2020 Bhavik Mehta. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Bhavik Mehta, Yaël Dillies
-/
import data.set_like.basic
import order.preorder_hom
import order.galois_connection
import tactic.monotonicity
/-!
# Closure operators between preorders
We define (bundled) closure operators on a preorder as monotone (increasing), extensive
(inflationary) and idempotent functions.
We define closed elements for the operator as elements which are fixed by it.
Lower adjoints to a function between preorders `u : β → α` allow to generalise closure operators to
situations where the closure operator we are dealing with naturally decomposes as `u ∘ l` where `l`
is a worthy function to have on its own. Typical examples include
`l : set G → subgroup G := subgroup.closure`, `u : subgroup G → set G := coe`, where `G` is a group.
This shows there is a close connection between closure operators, lower adjoints and Galois
connections/insertions: every Galois connection induces a lower adjoint which itself induces a
closure operator by composition (see `galois_connection.lower_adjoint` and
`lower_adjoint.closure_operator`), and every closure operator on a partial order induces a Galois
insertion from the set of closed elements to the underlying type (see `closure_operator.gi`).
## Main definitions
* `closure_operator`: A closure operator is a monotone function `f : α → α` such that
`∀ x, x ≤ f x` and `∀ x, f (f x) = f x`.
* `lower_adjoint`: A lower adjoint to `u : β → α` is a function `l : α → β` such that `l` and `u`
form a Galois connection.
## Implementation details
Although `lower_adjoint` is technically a generalisation of `closure_operator` (by defining
`to_fun := id`), it is desirable to have both as otherwise `id`s would be carried all over the
place when using concrete closure operators such as `convex_hull`.
`lower_adjoint` really is a semibundled `structure` version of `galois_connection`.
## References
* https://en.wikipedia.org/wiki/Closure_operator#Closure_operators_on_partially_ordered_sets
-/
universe u
/-! ### Closure operator -/
variable (α : Type*)
/-- A closure operator on the preorder `α` is a monotone function which is extensive (every `x`
is less than its closure) and idempotent. -/
structure closure_operator [preorder α] extends α →ₘ α :=
(le_closure' : ∀ x, x ≤ to_fun x)
(idempotent' : ∀ x, to_fun (to_fun x) = to_fun x)
namespace closure_operator
instance [preorder α] : has_coe_to_fun (closure_operator α) (λ _, α → α) := ⟨λ c, c.to_fun⟩
/-- See Note [custom simps projection] -/
def simps.apply [preorder α] (f : closure_operator α) : α → α := f
initialize_simps_projections closure_operator (to_preorder_hom_to_fun → apply, -to_preorder_hom)
section partial_order
variable [partial_order α]
/-- The identity function as a closure operator. -/
@[simps]
def id : closure_operator α :=
{ to_preorder_hom := preorder_hom.id,
le_closure' := λ _, le_rfl,
idempotent' := λ _, rfl }
instance : inhabited (closure_operator α) := ⟨id α⟩
variables {α} (c : closure_operator α)
@[ext] lemma ext :
∀ (c₁ c₂ : closure_operator α), (c₁ : α → α) = (c₂ : α → α) → c₁ = c₂
| ⟨⟨c₁, _⟩, _, _⟩ ⟨⟨c₂, _⟩, _, _⟩ h := by { congr, exact h }
/-- Constructor for a closure operator using the weaker idempotency axiom: `f (f x) ≤ f x`. -/
@[simps]
def mk' (f : α → α) (hf₁ : monotone f) (hf₂ : ∀ x, x ≤ f x) (hf₃ : ∀ x, f (f x) ≤ f x) :
closure_operator α :=
{ to_fun := f,
monotone' := hf₁,
le_closure' := hf₂,
idempotent' := λ x, (hf₃ x).antisymm (hf₁ (hf₂ x)) }
/-- Convenience constructor for a closure operator using the weaker minimality axiom:
`x ≤ f y → f x ≤ f y`, which is sometimes easier to prove in practice. -/
@[simps]
def mk₂ (f : α → α) (hf : ∀ x, x ≤ f x) (hmin : ∀ ⦃x y⦄, x ≤ f y → f x ≤ f y) :
closure_operator α :=
{ to_fun := f,
monotone' := λ x y hxy, hmin (hxy.trans (hf y)),
le_closure' := hf,
idempotent' := λ x, (hmin le_rfl).antisymm (hf _) }
/-- Expanded out version of `mk₂`. `p` implies being closed. This constructor should be used when
you already know a sufficient condition for being closed and using `mem_mk₃_closed` will avoid you
the (slight) hassle of having to prove it both inside and outside the constructor. -/
@[simps]
def mk₃ (f : α → α) (p : α → Prop) (hf : ∀ x, x ≤ f x) (hfp : ∀ x, p (f x))
(hmin : ∀ ⦃x y⦄, x ≤ y → p y → f x ≤ y) :
closure_operator α :=
mk₂ f hf (λ x y hxy, hmin hxy (hfp y))
/-- This lemma shows that the image of `x` of a closure operator built from the `mk₃` constructor
respects `p`, the property that was fed into it. -/
lemma closure_mem_mk₃ {f : α → α} {p : α → Prop} {hf : ∀ x, x ≤ f x} {hfp : ∀ x, p (f x)}
{hmin : ∀ ⦃x y⦄, x ≤ y → p y → f x ≤ y} (x : α) :
p (mk₃ f p hf hfp hmin x) :=
hfp x
/-- Analogue of `closure_le_closed_iff_le` but with the `p` that was fed into the `mk₃` constructor.
-/
lemma closure_le_mk₃_iff {f : α → α} {p : α → Prop} {hf : ∀ x, x ≤ f x} {hfp : ∀ x, p (f x)}
{hmin : ∀ ⦃x y⦄, x ≤ y → p y → f x ≤ y} {x y : α} (hxy : x ≤ y) (hy : p y) :
mk₃ f p hf hfp hmin x ≤ y :=
hmin hxy hy
@[mono] lemma monotone : monotone c := c.monotone'
/-- Every element is less than its closure. This property is sometimes referred to as extensivity or
inflationarity. -/
lemma le_closure (x : α) : x ≤ c x := c.le_closure' x
@[simp] lemma idempotent (x : α) : c (c x) = c x := c.idempotent' x
lemma le_closure_iff (x y : α) : x ≤ c y ↔ c x ≤ c y :=
⟨λ h, c.idempotent y ▸ c.monotone h, λ h, (c.le_closure x).trans h⟩
/-- An element `x` is closed for the closure operator `c` if it is a fixed point for it. -/
def closed : set α := λ x, c x = x
lemma mem_closed_iff (x : α) : x ∈ c.closed ↔ c x = x := iff.rfl
lemma mem_closed_iff_closure_le (x : α) : x ∈ c.closed ↔ c x ≤ x :=
⟨le_of_eq, λ h, h.antisymm (c.le_closure x)⟩
lemma closure_eq_self_of_mem_closed {x : α} (h : x ∈ c.closed) : c x = x := h
@[simp] lemma closure_is_closed (x : α) : c x ∈ c.closed := c.idempotent x
/-- The set of closed elements for `c` is exactly its range. -/
lemma closed_eq_range_close : c.closed = set.range c :=
set.ext $ λ x, ⟨λ h, ⟨x, h⟩, by { rintro ⟨y, rfl⟩, apply c.idempotent }⟩
/-- Send an `x` to an element of the set of closed elements (by taking the closure). -/
def to_closed (x : α) : c.closed := ⟨c x, c.closure_is_closed x⟩
@[simp] lemma closure_le_closed_iff_le (x : α) {y : α} (hy : c.closed y) : c x ≤ y ↔ x ≤ y :=
by rw [←c.closure_eq_self_of_mem_closed hy, ←le_closure_iff]
/-- A closure operator is equal to the closure operator obtained by feeding `c.closed` into the
`mk₃` constructor. -/
lemma eq_mk₃_closed (c : closure_operator α) :
c = mk₃ c c.closed c.le_closure c.closure_is_closed
(λ x y hxy hy, (c.closure_le_closed_iff_le x hy).2 hxy) :=
by { ext, refl }
/-- The property `p` fed into the `mk₃` constructor implies being closed. -/
lemma mem_mk₃_closed {f : α → α} {p : α → Prop} {hf : ∀ x, x ≤ f x} {hfp : ∀ x, p (f x)}
{hmin : ∀ ⦃x y⦄, x ≤ y → p y → f x ≤ y} {x : α} (hx : p x) :
x ∈ (mk₃ f p hf hfp hmin).closed :=
(hmin (le_refl _) hx).antisymm (hf _)
end partial_order
variable {α}
section order_top
variables [partial_order α] [order_top α] (c : closure_operator α)
@[simp] lemma closure_top : c ⊤ = ⊤ :=
le_top.antisymm (c.le_closure _)
lemma top_mem_closed : ⊤ ∈ c.closed :=
c.closure_top
end order_top
lemma closure_inf_le [semilattice_inf α] (c : closure_operator α) (x y : α) :
c (x ⊓ y) ≤ c x ⊓ c y :=
c.monotone.map_inf_le _ _
section semilattice_sup
variables [semilattice_sup α] (c : closure_operator α)
lemma closure_sup_closure_le (x y : α) :
c x ⊔ c y ≤ c (x ⊔ y) :=
c.monotone.le_map_sup _ _
lemma closure_sup_closure_left (x y : α) :
c (c x ⊔ y) = c (x ⊔ y) :=
((c.le_closure_iff _ _).1 (sup_le (c.monotone le_sup_left) (le_sup_right.trans
(c.le_closure _)))).antisymm (c.monotone (sup_le_sup_right (c.le_closure _) _))
lemma closure_sup_closure_right (x y : α) :
c (x ⊔ c y) = c (x ⊔ y) :=
by rw [sup_comm, closure_sup_closure_left, sup_comm]
lemma closure_sup_closure (x y : α) :
c (c x ⊔ c y) = c (x ⊔ y) :=
by rw [closure_sup_closure_left, closure_sup_closure_right]
end semilattice_sup
section complete_lattice
variables [complete_lattice α] (c : closure_operator α)
lemma closure_supr_closure {ι : Type u} (x : ι → α) :
c (⨆ i, c (x i)) = c (⨆ i, x i) :=
le_antisymm ((c.le_closure_iff _ _).1 (supr_le (λ i, c.monotone
(le_supr x i)))) (c.monotone (supr_le_supr (λ i, c.le_closure _)))
lemma closure_bsupr_closure (p : α → Prop) :
c (⨆ x (H : p x), c x) = c (⨆ x (H : p x), x) :=
le_antisymm ((c.le_closure_iff _ _).1 (bsupr_le (λ x hx, c.monotone
(le_bsupr_of_le x hx (le_refl x))))) (c.monotone (bsupr_le_bsupr (λ x hx, c.le_closure x)))
end complete_lattice
end closure_operator
/-! ### Lower adjoint -/
variables {α} {β : Type*}
/-- A lower adjoint of `u` on the preorder `α` is a function `l` such that `l` and `u` form a Galois
connection. It allows us to define closure operators whose output does not match the input. In
practice, `u` is often `coe : β → α`. -/
structure lower_adjoint [preorder α] [preorder β] (u : β → α) :=
(to_fun : α → β)
(gc' : galois_connection to_fun u)
namespace lower_adjoint
variable (α)
/-- The identity function as a lower adjoint to itself. -/
@[simps]
protected def id [preorder α] : lower_adjoint (id : α → α) :=
{ to_fun := λ x, x,
gc' := galois_connection.id }
variable {α}
instance [preorder α] : inhabited (lower_adjoint (id : α → α)) := ⟨lower_adjoint.id α⟩
section preorder
variables [preorder α] [preorder β] {u : β → α} (l : lower_adjoint u)
instance : has_coe_to_fun (lower_adjoint u) (λ _, α → β) := { coe := to_fun }
/-- See Note [custom simps projection] -/
def simps.apply : α → β := l
lemma gc : galois_connection l u := l.gc'
@[ext] lemma ext :
∀ (l₁ l₂ : lower_adjoint u), (l₁ : α → β) = (l₂ : α → β) → l₁ = l₂
| ⟨l₁, _⟩ ⟨l₂, _⟩ h := by { congr, exact h }
@[mono] lemma monotone : monotone (u ∘ l) := l.gc.monotone_u.comp l.gc.monotone_l
/-- Every element is less than its closure. This property is sometimes referred to as extensivity or
inflationarity. -/
lemma le_closure (x : α) : x ≤ u (l x) := l.gc.le_u_l _
end preorder
section partial_order
variables [partial_order α] [preorder β] {u : β → α} (l : lower_adjoint u)
/-- Every lower adjoint induces a closure operator given by the composition. This is the partial
order version of the statement that every adjunction induces a monad. -/
@[simps]
def closure_operator :
closure_operator α :=
{ to_fun := λ x, u (l x),
monotone' := l.monotone,
le_closure' := l.le_closure,
idempotent' := λ x, l.gc.u_l_u_eq_u (l x) }
lemma idempotent (x : α) : u (l (u (l x))) = u (l x) :=
l.closure_operator.idempotent _
lemma le_closure_iff (x y : α) : x ≤ u (l y) ↔ u (l x) ≤ u (l y) :=
l.closure_operator.le_closure_iff _ _
end partial_order
section preorder
variables [preorder α] [preorder β] {u : β → α} (l : lower_adjoint u)
/-- An element `x` is closed for `l : lower_adjoint u` if it is a fixed point: `u (l x) = x` -/
def closed : set α := λ x, u (l x) = x
lemma mem_closed_iff (x : α) : x ∈ l.closed ↔ u (l x) = x := iff.rfl
lemma closure_eq_self_of_mem_closed {x : α} (h : x ∈ l.closed) : u (l x) = x := h
end preorder
section partial_order
variables [partial_order α] [partial_order β] {u : β → α} (l : lower_adjoint u)
lemma mem_closed_iff_closure_le (x : α) : x ∈ l.closed ↔ u (l x) ≤ x :=
l.closure_operator.mem_closed_iff_closure_le _
@[simp] lemma closure_is_closed (x : α) : u (l x) ∈ l.closed := l.idempotent x
/-- The set of closed elements for `l` is the range of `u ∘ l`. -/
lemma closed_eq_range_close : l.closed = set.range (u ∘ l) :=
l.closure_operator.closed_eq_range_close
/-- Send an `x` to an element of the set of closed elements (by taking the closure). -/
def to_closed (x : α) : l.closed := ⟨u (l x), l.closure_is_closed x⟩
@[simp] lemma closure_le_closed_iff_le (x : α) {y : α} (hy : l.closed y) : u (l x) ≤ y ↔ x ≤ y :=
l.closure_operator.closure_le_closed_iff_le x hy
end partial_order
lemma closure_top [partial_order α] [order_top α] [preorder β] {u : β → α} (l : lower_adjoint u) :
u (l ⊤) = ⊤ :=
l.closure_operator.closure_top
lemma closure_inf_le [semilattice_inf α] [preorder β] {u : β → α} (l : lower_adjoint u) (x y : α) :
u (l (x ⊓ y)) ≤ u (l x) ⊓ u (l y) :=
l.closure_operator.closure_inf_le x y
section semilattice_sup
variables [semilattice_sup α] [preorder β] {u : β → α} (l : lower_adjoint u)
lemma closure_sup_closure_le (x y : α) :
u (l x) ⊔ u (l y) ≤ u (l (x ⊔ y)) :=
l.closure_operator.closure_sup_closure_le x y
lemma closure_sup_closure_left (x y : α) :
u (l (u (l x) ⊔ y)) = u (l (x ⊔ y)) :=
l.closure_operator.closure_sup_closure_left x y
lemma closure_sup_closure_right (x y : α) :
u (l (x ⊔ u (l y))) = u (l (x ⊔ y)) :=
l.closure_operator.closure_sup_closure_right x y
lemma closure_sup_closure (x y : α) :
u (l (u (l x) ⊔ u (l y))) = u (l (x ⊔ y)) :=
l.closure_operator.closure_sup_closure x y
end semilattice_sup
section complete_lattice
variables [complete_lattice α] [preorder β] {u : β → α} (l : lower_adjoint u)
lemma closure_supr_closure {ι : Type u} (x : ι → α) :
u (l (⨆ i, u (l (x i)))) = u (l (⨆ i, x i)) :=
l.closure_operator.closure_supr_closure x
lemma closure_bsupr_closure (p : α → Prop) :
u (l (⨆ x (H : p x), u (l x))) = u (l (⨆ x (H : p x), x)) :=
l.closure_operator.closure_bsupr_closure p
end complete_lattice
/- Lemmas for `lower_adjoint (coe : α → set β)`, where `set_like α β` -/
section coe_to_set
variables [set_like α β] (l : lower_adjoint (coe : α → set β))
lemma subset_closure (s : set β) : s ⊆ l s :=
l.le_closure s
lemma not_mem_of_not_mem_closure {s : set β} {P : β} (hP : P ∉ l s) : P ∉ s :=
λ h, hP (subset_closure _ s h)
lemma le_iff_subset (s : set β) (S : α) : l s ≤ S ↔ s ⊆ S :=
l.gc s S
lemma mem_iff (s : set β) (x : β) : x ∈ l s ↔ ∀ S : α, s ⊆ S → x ∈ S :=
by { simp_rw [←set_like.mem_coe, ←set.singleton_subset_iff, ←l.le_iff_subset],
exact ⟨λ h S, h.trans, λ h, h _ le_rfl⟩ }
lemma eq_of_le {s : set β} {S : α} (h₁ : s ⊆ S) (h₂ : S ≤ l s) : l s = S :=
((l.le_iff_subset _ _).2 h₁).antisymm h₂
lemma closure_union_closure_subset (x y : α) :
(l x : set β) ∪ (l y) ⊆ l (x ∪ y) :=
l.closure_sup_closure_le x y
@[simp] lemma closure_union_closure_left (x y : α) :
(l ((l x) ∪ y) : set β) = l (x ∪ y) :=
l.closure_sup_closure_left x y
@[simp] lemma closure_union_closure_right (x y : α) :
l (x ∪ (l y)) = l (x ∪ y) :=
set_like.coe_injective (l.closure_sup_closure_right x y)
@[simp] lemma closure_union_closure (x y : α) :
l ((l x) ∪ (l y)) = l (x ∪ y) :=
set_like.coe_injective (l.closure_operator.closure_sup_closure x y)
@[simp] lemma closure_Union_closure {ι : Type u} (x : ι → α) :
l (⋃ i, l (x i)) = l (⋃ i, x i) :=
set_like.coe_injective (l.closure_supr_closure (coe ∘ x))
@[simp] lemma closure_bUnion_closure (p : set β → Prop) :
l (⋃ x (H : p x), l x) = l (⋃ x (H : p x), x) :=
set_like.coe_injective (l.closure_bsupr_closure p)
end coe_to_set
end lower_adjoint
/-! ### Translations between `galois_connection`, `lower_adjoint`, `closure_operator` -/
variable {α}
/-- Every Galois connection induces a lower adjoint. -/
@[simps]
def galois_connection.lower_adjoint [preorder α] [preorder β] {l : α → β} {u : β → α}
(gc : galois_connection l u) :
lower_adjoint u :=
{ to_fun := l,
gc' := gc }
/-- Every Galois connection induces a closure operator given by the composition. This is the partial
order version of the statement that every adjunction induces a monad. -/
@[simps]
def galois_connection.closure_operator [partial_order α] [preorder β] {l : α → β} {u : β → α}
(gc : galois_connection l u) :
closure_operator α :=
gc.lower_adjoint.closure_operator
/-- The set of closed elements has a Galois insertion to the underlying type. -/
def closure_operator.gi [partial_order α] (c : closure_operator α) :
galois_insertion c.to_closed coe :=
{ choice := λ x hx, ⟨x, hx.antisymm (c.le_closure x)⟩,
gc := λ x y, (c.closure_le_closed_iff_le _ y.2),
le_l_u := λ x, c.le_closure _,
choice_eq := λ x hx, le_antisymm (c.le_closure x) hx }
/-- The Galois insertion associated to a closure operator can be used to reconstruct the closure
operator.
Note that the inverse in the opposite direction does not hold in general. -/
@[simp]
lemma closure_operator_gi_self [partial_order α] (c : closure_operator α) :
c.gi.gc.closure_operator = c :=
by { ext x, refl }
|
4f009e894ba8139f11ac38f5129096619e072199 | 07c76fbd96ea1786cc6392fa834be62643cea420 | /library/algebra/ordered_ring.lean | 38531ffbcce2448f6281fb88b9b9cfeb12b56424 | [
"Apache-2.0"
] | permissive | fpvandoorn/lean2 | 5a430a153b570bf70dc8526d06f18fc000a60ad9 | 0889cf65b7b3cebfb8831b8731d89c2453dd1e9f | refs/heads/master | 1,592,036,508,364 | 1,545,093,958,000 | 1,545,093,958,000 | 75,436,854 | 0 | 0 | null | 1,480,718,780,000 | 1,480,718,780,000 | null | UTF-8 | Lean | false | false | 28,487 | lean | /-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad
Here an "ordered_ring" is partially ordered ring, which is ordered with respect to both a weak
order and an associated strict order. Our numeric structures (int, rat, and real) will be instances
of "linear_ordered_comm_ring". This development is modeled after Isabelle's library.
-/
import algebra.ordered_group algebra.ring
open eq eq.ops
variable {A : Type}
private definition absurd_a_lt_a {B : Type} {a : A} [s : strict_order A] (H : a < a) : B :=
absurd H (lt.irrefl a)
/- semiring structures -/
structure ordered_semiring [class] (A : Type)
extends semiring A, ordered_cancel_comm_monoid A :=
(mul_le_mul_of_nonneg_left: ∀a b c, le a b → le zero c → le (mul c a) (mul c b))
(mul_le_mul_of_nonneg_right: ∀a b c, le a b → le zero c → le (mul a c) (mul b c))
(mul_lt_mul_of_pos_left: ∀a b c, lt a b → lt zero c → lt (mul c a) (mul c b))
(mul_lt_mul_of_pos_right: ∀a b c, lt a b → lt zero c → lt (mul a c) (mul b c))
section
variable [s : ordered_semiring A]
variables (a b c d e : A)
include s
theorem mul_le_mul_of_nonneg_left {a b c : A} (Hab : a ≤ b) (Hc : 0 ≤ c) :
c * a ≤ c * b := !ordered_semiring.mul_le_mul_of_nonneg_left Hab Hc
theorem mul_le_mul_of_nonneg_right {a b c : A} (Hab : a ≤ b) (Hc : 0 ≤ c) :
a * c ≤ b * c := !ordered_semiring.mul_le_mul_of_nonneg_right Hab Hc
-- TODO: there are four variations, depending on which variables we assume to be nonneg
theorem mul_le_mul {a b c d : A} (Hac : a ≤ c) (Hbd : b ≤ d) (nn_b : 0 ≤ b) (nn_c : 0 ≤ c) :
a * b ≤ c * d :=
calc
a * b ≤ c * b : mul_le_mul_of_nonneg_right Hac nn_b
... ≤ c * d : mul_le_mul_of_nonneg_left Hbd nn_c
theorem mul_nonneg {a b : A} (Ha : a ≥ 0) (Hb : b ≥ 0) : a * b ≥ 0 :=
begin
have H : 0 * b ≤ a * b, from mul_le_mul_of_nonneg_right Ha Hb,
rewrite zero_mul at H,
exact H
end
theorem mul_nonpos_of_nonneg_of_nonpos {a b : A} (Ha : a ≥ 0) (Hb : b ≤ 0) : a * b ≤ 0 :=
begin
have H : a * b ≤ a * 0, from mul_le_mul_of_nonneg_left Hb Ha,
rewrite mul_zero at H,
exact H
end
theorem mul_nonpos_of_nonpos_of_nonneg {a b : A} (Ha : a ≤ 0) (Hb : b ≥ 0) : a * b ≤ 0 :=
begin
have H : a * b ≤ 0 * b, from mul_le_mul_of_nonneg_right Ha Hb,
rewrite zero_mul at H,
exact H
end
theorem mul_lt_mul_of_pos_left {a b c : A} (Hab : a < b) (Hc : 0 < c) :
c * a < c * b := !ordered_semiring.mul_lt_mul_of_pos_left Hab Hc
theorem mul_lt_mul_of_pos_right {a b c : A} (Hab : a < b) (Hc : 0 < c) :
a * c < b * c := !ordered_semiring.mul_lt_mul_of_pos_right Hab Hc
-- TODO: once again, there are variations
theorem mul_lt_mul {a b c d : A} (Hac : a < c) (Hbd : b ≤ d) (pos_b : 0 < b) (nn_c : 0 ≤ c) :
a * b < c * d :=
calc
a * b < c * b : mul_lt_mul_of_pos_right Hac pos_b
... ≤ c * d : mul_le_mul_of_nonneg_left Hbd nn_c
theorem mul_lt_mul' {a b c d : A} (H1 : a < c) (H2 : b < d) (H3 : b ≥ 0) (H4 : c > 0) :
a * b < c * d :=
calc
a * b ≤ c * b : mul_le_mul_of_nonneg_right (le_of_lt H1) H3
... < c * d : mul_lt_mul_of_pos_left H2 H4
theorem mul_pos {a b : A} (Ha : a > 0) (Hb : b > 0) : a * b > 0 :=
begin
have H : 0 * b < a * b, from mul_lt_mul_of_pos_right Ha Hb,
rewrite zero_mul at H,
exact H
end
theorem mul_neg_of_pos_of_neg {a b : A} (Ha : a > 0) (Hb : b < 0) : a * b < 0 :=
begin
have H : a * b < a * 0, from mul_lt_mul_of_pos_left Hb Ha,
rewrite mul_zero at H,
exact H
end
theorem mul_neg_of_neg_of_pos {a b : A} (Ha : a < 0) (Hb : b > 0) : a * b < 0 :=
begin
have H : a * b < 0 * b, from mul_lt_mul_of_pos_right Ha Hb,
rewrite zero_mul at H,
exact H
end
theorem mul_self_lt_mul_self {a b : A} (H1 : 0 ≤ a) (H2 : a < b) : a * a < b * b :=
mul_lt_mul' H2 H2 H1 (lt_of_le_of_lt H1 H2)
end
structure linear_ordered_semiring [class] (A : Type)
extends ordered_semiring A, linear_strong_order_pair A :=
(zero_lt_one : lt zero one)
section
variable [s : linear_ordered_semiring A]
variables {a b c : A}
include s
theorem zero_lt_one : 0 < (1:A) := linear_ordered_semiring.zero_lt_one A
theorem zero_le_one : 0 ≤ (1:A) := le_of_lt zero_lt_one
theorem lt_of_mul_lt_mul_left (H : c * a < c * b) (Hc : c ≥ 0) : a < b :=
lt_of_not_ge
(assume H1 : b ≤ a,
have H2 : c * b ≤ c * a, from mul_le_mul_of_nonneg_left H1 Hc,
not_lt_of_ge H2 H)
theorem lt_of_mul_lt_mul_right (H : a * c < b * c) (Hc : c ≥ 0) : a < b :=
lt_of_not_ge
(assume H1 : b ≤ a,
have H2 : b * c ≤ a * c, from mul_le_mul_of_nonneg_right H1 Hc,
not_lt_of_ge H2 H)
theorem le_of_mul_le_mul_left (H : c * a ≤ c * b) (Hc : c > 0) : a ≤ b :=
le_of_not_gt
(assume H1 : b < a,
have H2 : c * b < c * a, from mul_lt_mul_of_pos_left H1 Hc,
not_le_of_gt H2 H)
theorem le_of_mul_le_mul_right (H : a * c ≤ b * c) (Hc : c > 0) : a ≤ b :=
le_of_not_gt
(assume H1 : b < a,
have H2 : b * c < a * c, from mul_lt_mul_of_pos_right H1 Hc,
not_le_of_gt H2 H)
theorem le_iff_mul_le_mul_left (a b : A) {c : A} (H : c > 0) : a ≤ b ↔ c * a ≤ c * b :=
iff.intro
(assume H', mul_le_mul_of_nonneg_left H' (le_of_lt H))
(assume H', le_of_mul_le_mul_left H' H)
theorem le_iff_mul_le_mul_right (a b : A) {c : A} (H : c > 0) : a ≤ b ↔ a * c ≤ b * c :=
iff.intro
(assume H', mul_le_mul_of_nonneg_right H' (le_of_lt H))
(assume H', le_of_mul_le_mul_right H' H)
theorem pos_of_mul_pos_left (H : 0 < a * b) (H1 : 0 ≤ a) : 0 < b :=
lt_of_not_ge
(assume H2 : b ≤ 0,
have H3 : a * b ≤ 0, from mul_nonpos_of_nonneg_of_nonpos H1 H2,
not_lt_of_ge H3 H)
theorem pos_of_mul_pos_right (H : 0 < a * b) (H1 : 0 ≤ b) : 0 < a :=
lt_of_not_ge
(assume H2 : a ≤ 0,
have H3 : a * b ≤ 0, from mul_nonpos_of_nonpos_of_nonneg H2 H1,
not_lt_of_ge H3 H)
theorem nonneg_of_mul_nonneg_left (H : 0 ≤ a * b) (H1 : 0 < a) : 0 ≤ b :=
le_of_not_gt
(assume H2 : b < 0,
not_le_of_gt (mul_neg_of_pos_of_neg H1 H2) H)
theorem nonneg_of_mul_nonneg_right (H : 0 ≤ a * b) (H1 : 0 < b) : 0 ≤ a :=
le_of_not_gt
(assume H2 : a < 0,
not_le_of_gt (mul_neg_of_neg_of_pos H2 H1) H)
theorem neg_of_mul_neg_left (H : a * b < 0) (H1 : 0 ≤ a) : b < 0 :=
lt_of_not_ge
(assume H2 : b ≥ 0,
not_lt_of_ge (mul_nonneg H1 H2) H)
theorem neg_of_mul_neg_right (H : a * b < 0) (H1 : 0 ≤ b) : a < 0 :=
lt_of_not_ge
(assume H2 : a ≥ 0,
not_lt_of_ge (mul_nonneg H2 H1) H)
theorem nonpos_of_mul_nonpos_left (H : a * b ≤ 0) (H1 : 0 < a) : b ≤ 0 :=
le_of_not_gt
(assume H2 : b > 0,
not_le_of_gt (mul_pos H1 H2) H)
theorem nonpos_of_mul_nonpos_right (H : a * b ≤ 0) (H1 : 0 < b) : a ≤ 0 :=
le_of_not_gt
(assume H2 : a > 0,
not_le_of_gt (mul_pos H2 H1) H)
end
structure decidable_linear_ordered_semiring [class] (A : Type)
extends linear_ordered_semiring A, decidable_linear_ordered_cancel_comm_monoid A
/- ring structures -/
structure ordered_ring [class] (A : Type)
extends ring A, ordered_comm_group A, zero_ne_one_class A :=
(mul_nonneg : ∀a b, le zero a → le zero b → le zero (mul a b))
(mul_pos : ∀a b, lt zero a → lt zero b → lt zero (mul a b))
theorem ordered_ring.mul_le_mul_of_nonneg_left [s : ordered_ring A] {a b c : A}
(Hab : a ≤ b) (Hc : 0 ≤ c) : c * a ≤ c * b :=
have H1 : 0 ≤ b - a, from iff.elim_right !sub_nonneg_iff_le Hab,
have H2 : 0 ≤ c * (b - a), from ordered_ring.mul_nonneg _ _ Hc H1,
begin
rewrite mul_sub_left_distrib at H2,
exact (iff.mp !sub_nonneg_iff_le H2)
end
theorem ordered_ring.mul_le_mul_of_nonneg_right [s : ordered_ring A] {a b c : A}
(Hab : a ≤ b) (Hc : 0 ≤ c) : a * c ≤ b * c :=
have H1 : 0 ≤ b - a, from iff.elim_right !sub_nonneg_iff_le Hab,
have H2 : 0 ≤ (b - a) * c, from ordered_ring.mul_nonneg _ _ H1 Hc,
begin
rewrite mul_sub_right_distrib at H2,
exact (iff.mp !sub_nonneg_iff_le H2)
end
theorem ordered_ring.mul_lt_mul_of_pos_left [s : ordered_ring A] {a b c : A}
(Hab : a < b) (Hc : 0 < c) : c * a < c * b :=
have H1 : 0 < b - a, from iff.elim_right !sub_pos_iff_lt Hab,
have H2 : 0 < c * (b - a), from ordered_ring.mul_pos _ _ Hc H1,
begin
rewrite mul_sub_left_distrib at H2,
exact (iff.mp !sub_pos_iff_lt H2)
end
theorem ordered_ring.mul_lt_mul_of_pos_right [s : ordered_ring A] {a b c : A}
(Hab : a < b) (Hc : 0 < c) : a * c < b * c :=
have H1 : 0 < b - a, from iff.elim_right !sub_pos_iff_lt Hab,
have H2 : 0 < (b - a) * c, from ordered_ring.mul_pos _ _ H1 Hc,
begin
rewrite mul_sub_right_distrib at H2,
exact (iff.mp !sub_pos_iff_lt H2)
end
definition ordered_ring.to_ordered_semiring [trans_instance]
[s : ordered_ring A] :
ordered_semiring A :=
⦃ ordered_semiring, s,
mul_zero := mul_zero,
zero_mul := zero_mul,
add_left_cancel := @add.left_cancel A _,
add_right_cancel := @add.right_cancel A _,
le_of_add_le_add_left := @le_of_add_le_add_left A _,
mul_le_mul_of_nonneg_left := @ordered_ring.mul_le_mul_of_nonneg_left A _,
mul_le_mul_of_nonneg_right := @ordered_ring.mul_le_mul_of_nonneg_right A _,
mul_lt_mul_of_pos_left := @ordered_ring.mul_lt_mul_of_pos_left A _,
mul_lt_mul_of_pos_right := @ordered_ring.mul_lt_mul_of_pos_right A _,
lt_of_add_lt_add_left := @lt_of_add_lt_add_left A _⦄
section
variable [s : ordered_ring A]
variables {a b c : A}
include s
theorem mul_le_mul_of_nonpos_left (H : b ≤ a) (Hc : c ≤ 0) : c * a ≤ c * b :=
have Hc' : -c ≥ 0, from iff.mpr !neg_nonneg_iff_nonpos Hc,
have H1 : -c * b ≤ -c * a, from mul_le_mul_of_nonneg_left H Hc',
have H2 : -(c * b) ≤ -(c * a),
begin
rewrite [-*neg_mul_eq_neg_mul at H1],
exact H1
end,
iff.mp !neg_le_neg_iff_le H2
theorem mul_le_mul_of_nonpos_right (H : b ≤ a) (Hc : c ≤ 0) : a * c ≤ b * c :=
have Hc' : -c ≥ 0, from iff.mpr !neg_nonneg_iff_nonpos Hc,
have H1 : b * -c ≤ a * -c, from mul_le_mul_of_nonneg_right H Hc',
have H2 : -(b * c) ≤ -(a * c),
begin
rewrite [-*neg_mul_eq_mul_neg at H1],
exact H1
end,
iff.mp !neg_le_neg_iff_le H2
theorem mul_nonneg_of_nonpos_of_nonpos (Ha : a ≤ 0) (Hb : b ≤ 0) : 0 ≤ a * b :=
begin
have H : 0 * b ≤ a * b, from mul_le_mul_of_nonpos_right Ha Hb,
rewrite zero_mul at H,
exact H
end
theorem mul_lt_mul_of_neg_left (H : b < a) (Hc : c < 0) : c * a < c * b :=
have Hc' : -c > 0, from iff.mpr !neg_pos_iff_neg Hc,
have H1 : -c * b < -c * a, from mul_lt_mul_of_pos_left H Hc',
have H2 : -(c * b) < -(c * a),
begin
rewrite [-*neg_mul_eq_neg_mul at H1],
exact H1
end,
iff.mp !neg_lt_neg_iff_lt H2
theorem mul_lt_mul_of_neg_right (H : b < a) (Hc : c < 0) : a * c < b * c :=
have Hc' : -c > 0, from iff.mpr !neg_pos_iff_neg Hc,
have H1 : b * -c < a * -c, from mul_lt_mul_of_pos_right H Hc',
have H2 : -(b * c) < -(a * c),
begin
rewrite [-*neg_mul_eq_mul_neg at H1],
exact H1
end,
iff.mp !neg_lt_neg_iff_lt H2
theorem mul_pos_of_neg_of_neg (Ha : a < 0) (Hb : b < 0) : 0 < a * b :=
begin
have H : 0 * b < a * b, from mul_lt_mul_of_neg_right Ha Hb,
rewrite zero_mul at H,
exact H
end
end
-- TODO: we can eliminate mul_pos_of_pos, but now it is not worth the effort to redeclare the
-- class instance
structure linear_ordered_ring [class] (A : Type)
extends ordered_ring A, linear_strong_order_pair A :=
(zero_lt_one : lt zero one)
definition linear_ordered_ring.to_linear_ordered_semiring [trans_instance]
[s : linear_ordered_ring A] :
linear_ordered_semiring A :=
⦃ linear_ordered_semiring, s,
mul_zero := mul_zero,
zero_mul := zero_mul,
add_left_cancel := @add.left_cancel A _,
add_right_cancel := @add.right_cancel A _,
le_of_add_le_add_left := @le_of_add_le_add_left A _,
mul_le_mul_of_nonneg_left := @mul_le_mul_of_nonneg_left A _,
mul_le_mul_of_nonneg_right := @mul_le_mul_of_nonneg_right A _,
mul_lt_mul_of_pos_left := @mul_lt_mul_of_pos_left A _,
mul_lt_mul_of_pos_right := @mul_lt_mul_of_pos_right A _,
le_total := linear_ordered_ring.le_total,
lt_of_add_lt_add_left := @lt_of_add_lt_add_left A _ ⦄
structure linear_ordered_comm_ring [class] (A : Type) extends linear_ordered_ring A, comm_monoid A
theorem linear_ordered_comm_ring.eq_zero_or_eq_zero_of_mul_eq_zero [s : linear_ordered_comm_ring A]
{a b : A} (H : a * b = 0) : a = 0 ∨ b = 0 :=
lt.by_cases
(assume Ha : 0 < a,
lt.by_cases
(assume Hb : 0 < b,
begin
have H1 : 0 < a * b, from mul_pos Ha Hb,
rewrite H at H1,
apply absurd_a_lt_a H1
end)
(assume Hb : 0 = b, or.inr (Hb⁻¹))
(assume Hb : 0 > b,
begin
have H1 : 0 > a * b, from mul_neg_of_pos_of_neg Ha Hb,
rewrite H at H1,
apply absurd_a_lt_a H1
end))
(assume Ha : 0 = a, or.inl (Ha⁻¹))
(assume Ha : 0 > a,
lt.by_cases
(assume Hb : 0 < b,
begin
have H1 : 0 > a * b, from mul_neg_of_neg_of_pos Ha Hb,
rewrite H at H1,
apply absurd_a_lt_a H1
end)
(assume Hb : 0 = b, or.inr (Hb⁻¹))
(assume Hb : 0 > b,
begin
have H1 : 0 < a * b, from mul_pos_of_neg_of_neg Ha Hb,
rewrite H at H1,
apply absurd_a_lt_a H1
end))
-- Linearity implies no zero divisors. Doesn't need commutativity.
definition linear_ordered_comm_ring.to_integral_domain [trans_instance]
[s: linear_ordered_comm_ring A] : integral_domain A :=
⦃ integral_domain, s,
eq_zero_or_eq_zero_of_mul_eq_zero :=
@linear_ordered_comm_ring.eq_zero_or_eq_zero_of_mul_eq_zero A s ⦄
section
variable [s : linear_ordered_ring A]
variables (a b c : A)
include s
theorem mul_self_nonneg : a * a ≥ 0 :=
or.elim (le.total 0 a)
(assume H : a ≥ 0, mul_nonneg H H)
(assume H : a ≤ 0, mul_nonneg_of_nonpos_of_nonpos H H)
theorem pos_and_pos_or_neg_and_neg_of_mul_pos {a b : A} (Hab : a * b > 0) :
(a > 0 ∧ b > 0) ∨ (a < 0 ∧ b < 0) :=
lt.by_cases
(assume Ha : 0 < a,
lt.by_cases
(assume Hb : 0 < b, or.inl (and.intro Ha Hb))
(assume Hb : 0 = b,
begin
rewrite [-Hb at Hab, mul_zero at Hab],
apply absurd_a_lt_a Hab
end)
(assume Hb : b < 0,
absurd Hab (lt.asymm (mul_neg_of_pos_of_neg Ha Hb))))
(assume Ha : 0 = a,
begin
rewrite [-Ha at Hab, zero_mul at Hab],
apply absurd_a_lt_a Hab
end)
(assume Ha : a < 0,
lt.by_cases
(assume Hb : 0 < b,
absurd Hab (lt.asymm (mul_neg_of_neg_of_pos Ha Hb)))
(assume Hb : 0 = b,
begin
rewrite [-Hb at Hab, mul_zero at Hab],
apply absurd_a_lt_a Hab
end)
(assume Hb : b < 0, or.inr (and.intro Ha Hb)))
theorem gt_of_mul_lt_mul_neg_left {a b c : A} (H : c * a < c * b) (Hc : c ≤ 0) : a > b :=
have nhc : -c ≥ 0, from neg_nonneg_of_nonpos Hc,
have H2 : -(c * b) < -(c * a), from iff.mpr (neg_lt_neg_iff_lt _ _) H,
have H3 : (-c) * b < (-c) * a, from calc
(-c) * b = - (c * b) : neg_mul_eq_neg_mul
... < -(c * a) : H2
... = (-c) * a : neg_mul_eq_neg_mul,
lt_of_mul_lt_mul_left H3 nhc
theorem zero_gt_neg_one : -1 < (0:A) :=
neg_zero ▸ (neg_lt_neg zero_lt_one)
theorem le_of_mul_le_of_ge_one {a b c : A} (H : a * c ≤ b) (Hb : b ≥ 0) (Hc : c ≥ 1) : a ≤ b :=
have H' : a * c ≤ b * c, from calc
a * c ≤ b : H
... = b * 1 : mul_one
... ≤ b * c : mul_le_mul_of_nonneg_left Hc Hb,
le_of_mul_le_mul_right H' (lt_of_lt_of_le zero_lt_one Hc)
theorem nonneg_le_nonneg_of_squares_le {a b : A} (Ha : a ≥ 0) (Hb : b ≥ 0) (H : a * a ≤ b * b) :
a ≤ b :=
begin
apply le_of_not_gt,
intro Hab,
note Hposa := lt_of_le_of_lt Hb Hab,
note H' := calc
b * b ≤ a * b : mul_le_mul_of_nonneg_right (le_of_lt Hab) Hb
... < a * a : mul_lt_mul_of_pos_left Hab Hposa,
apply (not_le_of_gt H') H
end
end
/- TODO: Isabelle's library has all kinds of cancelation rules for the simplifier.
Search on mult_le_cancel_right1 in Rings.thy. -/
structure decidable_linear_ordered_comm_ring [class] (A : Type) extends linear_ordered_comm_ring A,
decidable_linear_ordered_comm_group A
definition decidable_linear_ordered_comm_ring.to_decidable_linear_ordered_semiring
[trans_instance] [s : decidable_linear_ordered_comm_ring A] :
decidable_linear_ordered_semiring A :=
⦃decidable_linear_ordered_semiring, s, @linear_ordered_ring.to_linear_ordered_semiring A _⦄
section
variable [s : decidable_linear_ordered_comm_ring A]
variables {a b c : A}
include s
definition sign (a : A) : A := lt.cases a 0 (-1) 0 1
theorem sign_of_neg (H : a < 0) : sign a = -1 := lt.cases_of_lt H
theorem sign_zero : sign 0 = (0:A) := lt.cases_of_eq rfl
theorem sign_of_pos (H : a > 0) : sign a = 1 := lt.cases_of_gt H
theorem sign_one : sign 1 = (1:A) := sign_of_pos zero_lt_one
theorem sign_neg_one : sign (-1) = -(1:A) := sign_of_neg (neg_neg_of_pos zero_lt_one)
theorem sign_sign (a : A) : sign (sign a) = sign a :=
lt.by_cases
(assume H : a > 0,
calc
sign (sign a) = sign 1 : by rewrite (sign_of_pos H)
... = 1 : by rewrite sign_one
... = sign a : by rewrite (sign_of_pos H))
(assume H : 0 = a,
calc
sign (sign a) = sign (sign 0) : by rewrite H
... = sign 0 : by rewrite sign_zero at {1}
... = sign a : by rewrite -H)
(assume H : a < 0,
calc
sign (sign a) = sign (-1) : by rewrite (sign_of_neg H)
... = -1 : by rewrite sign_neg_one
... = sign a : by rewrite (sign_of_neg H))
theorem pos_of_sign_eq_one (H : sign a = 1) : a > 0 :=
lt.by_cases
(assume H1 : 0 < a, H1)
(assume H1 : 0 = a,
begin
rewrite [-H1 at H, sign_zero at H],
apply absurd H zero_ne_one
end)
(assume H1 : 0 > a,
have H2 : -1 = 1, from (sign_of_neg H1)⁻¹ ⬝ H,
absurd ((eq_zero_of_neg_eq H2)⁻¹) zero_ne_one)
theorem eq_zero_of_sign_eq_zero (H : sign a = 0) : a = 0 :=
lt.by_cases
(assume H1 : 0 < a,
absurd (H⁻¹ ⬝ sign_of_pos H1) zero_ne_one)
(assume H1 : 0 = a, H1⁻¹)
(assume H1 : 0 > a,
have H2 : 0 = -1, from H⁻¹ ⬝ sign_of_neg H1,
have H3 : 1 = 0, from eq_neg_of_eq_neg H2 ⬝ neg_zero,
absurd (H3⁻¹) zero_ne_one)
theorem neg_of_sign_eq_neg_one (H : sign a = -1) : a < 0 :=
lt.by_cases
(assume H1 : 0 < a,
have H2 : -1 = 1, from H⁻¹ ⬝ (sign_of_pos H1),
absurd ((eq_zero_of_neg_eq H2)⁻¹) zero_ne_one)
(assume H1 : 0 = a,
have H2 : (0:A) = -1,
begin
rewrite [-H1 at H, sign_zero at H],
exact H
end,
have H3 : 1 = 0, from eq_neg_of_eq_neg H2 ⬝ neg_zero,
absurd (H3⁻¹) zero_ne_one)
(assume H1 : 0 > a, H1)
theorem sign_neg (a : A) : sign (-a) = -(sign a) :=
lt.by_cases
(assume H1 : 0 < a,
calc
sign (-a) = -1 : sign_of_neg (neg_neg_of_pos H1)
... = -(sign a) : by rewrite (sign_of_pos H1))
(assume H1 : 0 = a,
calc
sign (-a) = sign (-0) : by rewrite H1
... = sign 0 : by rewrite neg_zero
... = 0 : by rewrite sign_zero
... = -0 : by rewrite neg_zero
... = -(sign 0) : by rewrite sign_zero
... = -(sign a) : by rewrite -H1)
(assume H1 : 0 > a,
calc
sign (-a) = 1 : sign_of_pos (neg_pos_of_neg H1)
... = -(-1) : by rewrite neg_neg
... = -(sign a) : sign_of_neg H1)
theorem sign_mul (a b : A) : sign (a * b) = sign a * sign b :=
lt.by_cases
(assume z_lt_a : 0 < a,
lt.by_cases
(assume z_lt_b : 0 < b,
by rewrite [sign_of_pos z_lt_a, sign_of_pos z_lt_b,
sign_of_pos (mul_pos z_lt_a z_lt_b), one_mul])
(assume z_eq_b : 0 = b, by rewrite [-z_eq_b, mul_zero, *sign_zero, mul_zero])
(assume z_gt_b : 0 > b,
by rewrite [sign_of_pos z_lt_a, sign_of_neg z_gt_b,
sign_of_neg (mul_neg_of_pos_of_neg z_lt_a z_gt_b), one_mul]))
(assume z_eq_a : 0 = a, by rewrite [-z_eq_a, zero_mul, *sign_zero, zero_mul])
(assume z_gt_a : 0 > a,
lt.by_cases
(assume z_lt_b : 0 < b,
by rewrite [sign_of_neg z_gt_a, sign_of_pos z_lt_b,
sign_of_neg (mul_neg_of_neg_of_pos z_gt_a z_lt_b), mul_one])
(assume z_eq_b : 0 = b, by rewrite [-z_eq_b, mul_zero, *sign_zero, mul_zero])
(assume z_gt_b : 0 > b,
by rewrite [sign_of_neg z_gt_a, sign_of_neg z_gt_b,
sign_of_pos (mul_pos_of_neg_of_neg z_gt_a z_gt_b),
neg_mul_neg, one_mul]))
theorem abs_eq_sign_mul (a : A) : abs a = sign a * a :=
lt.by_cases
(assume H1 : 0 < a,
calc
abs a = a : abs_of_pos H1
... = 1 * a : by rewrite one_mul
... = sign a * a : by rewrite (sign_of_pos H1))
(assume H1 : 0 = a,
calc
abs a = abs 0 : by rewrite H1
... = 0 : by rewrite abs_zero
... = 0 * a : by rewrite zero_mul
... = sign 0 * a : by rewrite sign_zero
... = sign a * a : by rewrite H1)
(assume H1 : a < 0,
calc
abs a = -a : abs_of_neg H1
... = -1 * a : by rewrite neg_eq_neg_one_mul
... = sign a * a : by rewrite (sign_of_neg H1))
theorem eq_sign_mul_abs (a : A) : a = sign a * abs a :=
lt.by_cases
(assume H1 : 0 < a,
calc
a = abs a : abs_of_pos H1
... = 1 * abs a : by rewrite one_mul
... = sign a * abs a : by rewrite (sign_of_pos H1))
(assume H1 : 0 = a,
calc
a = 0 : H1⁻¹
... = 0 * abs a : by rewrite zero_mul
... = sign 0 * abs a : by rewrite sign_zero
... = sign a * abs a : by rewrite H1)
(assume H1 : a < 0,
calc
a = -(-a) : by rewrite neg_neg
... = -abs a : by rewrite (abs_of_neg H1)
... = -1 * abs a : by rewrite neg_eq_neg_one_mul
... = sign a * abs a : by rewrite (sign_of_neg H1))
theorem abs_dvd_iff (a b : A) : abs a ∣ b ↔ a ∣ b :=
abs.by_cases !iff.refl !neg_dvd_iff_dvd
theorem abs_dvd_of_dvd {a b : A} : a ∣ b → abs a ∣ b :=
iff.mpr !abs_dvd_iff
theorem dvd_abs_iff (a b : A) : a ∣ abs b ↔ a ∣ b :=
abs.by_cases !iff.refl !dvd_neg_iff_dvd
theorem dvd_abs_of_dvd {a b : A} : a ∣ b → a ∣ abs b :=
iff.mpr !dvd_abs_iff
theorem abs_mul (a b : A) : abs (a * b) = abs a * abs b :=
or.elim (le.total 0 a)
(assume H1 : 0 ≤ a,
or.elim (le.total 0 b)
(assume H2 : 0 ≤ b,
calc
abs (a * b) = a * b : abs_of_nonneg (mul_nonneg H1 H2)
... = abs a * b : by rewrite (abs_of_nonneg H1)
... = abs a * abs b : by rewrite (abs_of_nonneg H2))
(assume H2 : b ≤ 0,
calc
abs (a * b) = -(a * b) : abs_of_nonpos (mul_nonpos_of_nonneg_of_nonpos H1 H2)
... = a * -b : by rewrite neg_mul_eq_mul_neg
... = abs a * -b : by rewrite (abs_of_nonneg H1)
... = abs a * abs b : by rewrite (abs_of_nonpos H2)))
(assume H1 : a ≤ 0,
or.elim (le.total 0 b)
(assume H2 : 0 ≤ b,
calc
abs (a * b) = -(a * b) : abs_of_nonpos (mul_nonpos_of_nonpos_of_nonneg H1 H2)
... = -a * b : by rewrite neg_mul_eq_neg_mul
... = abs a * b : by rewrite (abs_of_nonpos H1)
... = abs a * abs b : by rewrite (abs_of_nonneg H2))
(assume H2 : b ≤ 0,
calc
abs (a * b) = a * b : abs_of_nonneg (mul_nonneg_of_nonpos_of_nonpos H1 H2)
... = -a * -b : by rewrite neg_mul_neg
... = abs a * -b : by rewrite (abs_of_nonpos H1)
... = abs a * abs b : by rewrite (abs_of_nonpos H2)))
theorem abs_mul_abs_self (a : A) : abs a * abs a = a * a :=
abs.by_cases rfl !neg_mul_neg
theorem abs_mul_self (a : A) : abs (a * a) = a * a :=
by rewrite [abs_mul, abs_mul_abs_self]
theorem sub_le_of_abs_sub_le_left (H : abs (a - b) ≤ c) : b - c ≤ a :=
if Hz : 0 ≤ a - b then
(calc
a ≥ b : (iff.mp !sub_nonneg_iff_le) Hz
... ≥ b - c : sub_le_of_nonneg _ (le.trans !abs_nonneg H))
else
(have Habs : b - a ≤ c, by rewrite [abs_of_neg (lt_of_not_ge Hz) at H, neg_sub at H]; apply H,
have Habs' : b ≤ c + a, from (iff.mpr !le_add_iff_sub_right_le) Habs,
(iff.mp !le_add_iff_sub_left_le) Habs')
theorem sub_le_of_abs_sub_le_right (H : abs (a - b) ≤ c) : a - c ≤ b :=
sub_le_of_abs_sub_le_left (!abs_sub ▸ H)
theorem sub_lt_of_abs_sub_lt_left (H : abs (a - b) < c) : b - c < a :=
if Hz : 0 ≤ a - b then
(calc
a ≥ b : (iff.mp !sub_nonneg_iff_le) Hz
... > b - c : sub_lt_of_pos _ (lt_of_le_of_lt !abs_nonneg H))
else
(have Habs : b - a < c, by rewrite [abs_of_neg (lt_of_not_ge Hz) at H, neg_sub at H]; apply H,
have Habs' : b < c + a, from lt_add_of_sub_lt_right Habs,
sub_lt_left_of_lt_add Habs')
theorem sub_lt_of_abs_sub_lt_right (H : abs (a - b) < c) : a - c < b :=
sub_lt_of_abs_sub_lt_left (!abs_sub ▸ H)
theorem abs_sub_square (a b : A) : abs (a - b) * abs (a - b) = a * a + b * b - (1 + 1) * a * b :=
begin
rewrite [abs_mul_abs_self, *mul_sub_left_distrib, *mul_sub_right_distrib,
sub_eq_add_neg (a*b), sub_add_eq_sub_sub, sub_neg_eq_add, *right_distrib, sub_add_eq_sub_sub, *one_mul,
*add.assoc, {_ + b * b}add.comm, *sub_eq_add_neg],
rewrite [{a*a + b*b}add.comm],
rewrite [mul.comm b a, *add.assoc]
end
theorem abs_abs_sub_abs_le_abs_sub (a b : A) : abs (abs a - abs b) ≤ abs (a - b) :=
begin
apply nonneg_le_nonneg_of_squares_le,
repeat apply abs_nonneg,
rewrite [*abs_sub_square, *abs_abs, *abs_mul_abs_self],
apply sub_le_sub_left,
rewrite *mul.assoc,
apply mul_le_mul_of_nonneg_left,
rewrite -abs_mul,
apply le_abs_self,
apply le_of_lt,
apply add_pos,
apply zero_lt_one,
apply zero_lt_one
end
lemma eq_zero_of_mul_self_add_mul_self_eq_zero {x y : A} (H : x * x + y * y = 0) : x = 0 :=
have x * x ≤ (0 : A), from calc
x * x ≤ x * x + y * y : le_add_of_nonneg_right (mul_self_nonneg y)
... = 0 : H,
eq_zero_of_mul_self_eq_zero (le.antisymm this (mul_self_nonneg x))
end
/- TODO: Multiplication and one, starting with mult_right_le_one_le. -/
namespace norm_num
theorem pos_bit0_helper [s : linear_ordered_semiring A] (a : A) (H : a > 0) : bit0 a > 0 :=
by rewrite ↑bit0; apply add_pos H H
theorem nonneg_bit0_helper [s : linear_ordered_semiring A] (a : A) (H : a ≥ 0) : bit0 a ≥ 0 :=
by rewrite ↑bit0; apply add_nonneg H H
theorem pos_bit1_helper [s : linear_ordered_semiring A] (a : A) (H : a ≥ 0) : bit1 a > 0 :=
begin
rewrite ↑bit1,
apply add_pos_of_nonneg_of_pos,
apply nonneg_bit0_helper _ H,
apply zero_lt_one
end
theorem nonneg_bit1_helper [s : linear_ordered_semiring A] (a : A) (H : a ≥ 0) : bit1 a ≥ 0 :=
by apply le_of_lt; apply pos_bit1_helper _ H
theorem nonzero_of_pos_helper [s : linear_ordered_semiring A] (a : A) (H : a > 0) : a ≠ 0 :=
ne_of_gt H
theorem nonzero_of_neg_helper [s : linear_ordered_ring A] (a : A) (H : a ≠ 0) : -a ≠ 0 :=
begin intro Ha, apply H, apply eq_of_neg_eq_neg, rewrite neg_zero, exact Ha end
end norm_num
|
f270c154688e366ecae108412cc95414965f72da | 9028d228ac200bbefe3a711342514dd4e4458bff | /src/group_theory/sylow.lean | 4a635adcb095b6a35bb78b26a4b91c908b80baeb | [
"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 | 12,388 | lean | /-
Copyright (c) 2018 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes
-/
import group_theory.group_action
import group_theory.quotient_group
import group_theory.order_of_element
import data.zmod.basic
import data.fintype.card
import data.list.rotate
open equiv fintype finset mul_action function
open equiv.perm subgroup list quotient_group
open_locale big_operators
universes u v w
variables {G : Type u} {α : Type v} {β : Type w} [group G]
local attribute [instance, priority 10] subtype.fintype set_fintype classical.prop_decidable
namespace mul_action
variables [mul_action G α]
lemma mem_fixed_points_iff_card_orbit_eq_one {a : α}
[fintype (orbit G a)] : a ∈ fixed_points G α ↔ card (orbit G a) = 1 :=
begin
rw [fintype.card_eq_one_iff, mem_fixed_points],
split,
{ exact λ h, ⟨⟨a, mem_orbit_self _⟩, λ ⟨b, ⟨x, hx⟩⟩, subtype.eq $ by simp [h x, hx.symm]⟩ },
{ assume h x,
rcases h with ⟨⟨z, hz⟩, hz₁⟩,
exact calc x • a = z : subtype.mk.inj (hz₁ ⟨x • a, mem_orbit _ _⟩)
... = a : (subtype.mk.inj (hz₁ ⟨a, mem_orbit_self _⟩)).symm }
end
lemma card_modeq_card_fixed_points [fintype α] [fintype G] [fintype (fixed_points G α)]
(p : ℕ) {n : ℕ} [hp : fact p.prime] (h : card G = p ^ n) :
card α ≡ card (fixed_points G α) [MOD p] :=
calc card α = card (Σ y : quotient (orbit_rel G α), {x // quotient.mk' x = y}) :
card_congr (sigma_preimage_equiv (@quotient.mk' _ (orbit_rel G α))).symm
... = ∑ a : quotient (orbit_rel G α), card {x // quotient.mk' x = a} : card_sigma _
... ≡ ∑ a : fixed_points G α, 1 [MOD p] :
begin
rw [← zmod.eq_iff_modeq_nat p, sum_nat_cast, sum_nat_cast],
refine eq.symm (sum_bij_ne_zero (λ a _ _, quotient.mk' a.1)
(λ _ _ _, mem_univ _)
(λ a₁ a₂ _ _ _ _ h,
subtype.eq ((mem_fixed_points' α).1 a₂.2 a₁.1 (quotient.exact' h)))
(λ b, _)
(λ a ha _, by rw [← mem_fixed_points_iff_card_orbit_eq_one.1 a.2];
simp only [quotient.eq']; congr)),
{ refine quotient.induction_on' b (λ b _ hb, _),
have : card (orbit G b) ∣ p ^ n,
{ rw [← h, fintype.card_congr (orbit_equiv_quotient_stabilizer G b)];
exact card_quotient_dvd_card _ },
rcases (nat.dvd_prime_pow hp).1 this with ⟨k, _, hk⟩,
have hb' :¬ p ^ 1 ∣ p ^ k,
{ rw [pow_one, ← hk, ← nat.modeq.modeq_zero_iff, ← zmod.eq_iff_modeq_nat,
nat.cast_zero, ← ne.def],
exact eq.mpr (by simp only [quotient.eq']; congr) hb },
have : k = 0 := nat.le_zero_iff.1 (nat.le_of_lt_succ (lt_of_not_ge (mt (pow_dvd_pow p) hb'))),
refine ⟨⟨b, mem_fixed_points_iff_card_orbit_eq_one.2 $ by rw [hk, this, pow_zero]⟩,
mem_univ _, _, rfl⟩,
rw [nat.cast_one], exact one_ne_zero }
end
... = _ : by simp; refl
end mul_action
lemma quotient_group.card_preimage_mk [fintype G] (s : subgroup G)
(t : set (quotient s)) : fintype.card (quotient_group.mk ⁻¹' t) =
fintype.card s * fintype.card t :=
by rw [← fintype.card_prod, fintype.card_congr
(preimage_mk_equiv_subgroup_times_set _ _)]
namespace sylow
/-- Given a vector `v` of length `n`, make a vector of length `n+1` whose product is `1`,
by consing the the inverse of the product of `v`. -/
def mk_vector_prod_eq_one (n : ℕ) (v : vector G n) : vector G (n+1) :=
v.to_list.prod⁻¹ ::ᵥ v
lemma mk_vector_prod_eq_one_injective (n : ℕ) : injective (@mk_vector_prod_eq_one G _ n) :=
λ ⟨v, _⟩ ⟨w, _⟩ h, subtype.eq (show v = w, by injection h with h; injection h)
/-- The type of vectors with terms from `G`, length `n`, and product equal to `1:G`. -/
def vectors_prod_eq_one (G : Type*) [group G] (n : ℕ) : set (vector G n) :=
{v | v.to_list.prod = 1}
lemma mem_vectors_prod_eq_one {n : ℕ} (v : vector G n) :
v ∈ vectors_prod_eq_one G n ↔ v.to_list.prod = 1 := iff.rfl
lemma mem_vectors_prod_eq_one_iff {n : ℕ} (v : vector G (n + 1)) :
v ∈ vectors_prod_eq_one G (n + 1) ↔ v ∈ set.range (@mk_vector_prod_eq_one G _ n) :=
⟨λ (h : v.to_list.prod = 1), ⟨v.tail,
begin
unfold mk_vector_prod_eq_one,
conv {to_rhs, rw ← vector.cons_head_tail v},
suffices : (v.tail.to_list.prod)⁻¹ = v.head,
{ rw this },
rw [← mul_left_inj v.tail.to_list.prod, inv_mul_self, ← list.prod_cons,
← vector.to_list_cons, vector.cons_head_tail, h]
end⟩,
λ ⟨w, hw⟩, by rw [mem_vectors_prod_eq_one, ← hw, mk_vector_prod_eq_one,
vector.to_list_cons, list.prod_cons, inv_mul_self]⟩
/-- The rotation action of `zmod n` (viewed as multiplicative group) on
`vectors_prod_eq_one G n`, where `G` is a multiplicative group. -/
def rotate_vectors_prod_eq_one (G : Type*) [group G] (n : ℕ)
(m : multiplicative (zmod n)) (v : vectors_prod_eq_one G n) : vectors_prod_eq_one G n :=
⟨⟨v.1.to_list.rotate m.val, by simp⟩, prod_rotate_eq_one_of_prod_eq_one v.2 _⟩
instance rotate_vectors_prod_eq_one.mul_action (n : ℕ) [fact (0 < n)] :
mul_action (multiplicative (zmod n)) (vectors_prod_eq_one G n) :=
{ smul := (rotate_vectors_prod_eq_one G n),
one_smul :=
begin
intro v, apply subtype.eq, apply vector.eq _ _,
show rotate _ (0 : zmod n).val = _, rw zmod.val_zero,
exact rotate_zero v.1.to_list
end,
mul_smul := λ a b ⟨⟨v, hv₁⟩, hv₂⟩, subtype.eq $ vector.eq _ _ $
show v.rotate ((a + b : zmod n).val) = list.rotate (list.rotate v (b.val)) (a.val),
by rw [zmod.val_add, rotate_rotate, ← rotate_mod _ (b.val + a.val), add_comm, hv₁] }
lemma one_mem_vectors_prod_eq_one (n : ℕ) : vector.repeat (1 : G) n ∈ vectors_prod_eq_one G n :=
by simp [vector.repeat, vectors_prod_eq_one]
lemma one_mem_fixed_points_rotate (n : ℕ) [fact (0 < n)] :
(⟨vector.repeat (1 : G) n, one_mem_vectors_prod_eq_one n⟩ : vectors_prod_eq_one G n) ∈
fixed_points (multiplicative (zmod n)) (vectors_prod_eq_one G n) :=
λ m, subtype.eq $ vector.eq _ _ $
rotate_eq_self_iff_eq_repeat.2 ⟨(1 : G),
show list.repeat (1 : G) n = list.repeat 1 (list.repeat (1 : G) n).length, by simp⟩ _
/-- Cauchy's theorem -/
lemma exists_prime_order_of_dvd_card [fintype G] (p : ℕ) [hp : fact p.prime]
(hdvd : p ∣ card G) : ∃ x : G, order_of x = p :=
let n : ℕ+ := ⟨p - 1, nat.sub_pos_of_lt hp.one_lt⟩ in
have hn : p = n + 1 := nat.succ_sub hp.pos,
have hcard : card (vectors_prod_eq_one G (n + 1)) = card G ^ (n : ℕ),
by rw [set.ext mem_vectors_prod_eq_one_iff,
set.card_range_of_injective (mk_vector_prod_eq_one_injective _), card_vector],
have hzmod : fintype.card (multiplicative (zmod p)) = p ^ 1,
by { rw pow_one p, exact zmod.card p },
have hmodeq : _ = _ := @mul_action.card_modeq_card_fixed_points
(multiplicative (zmod p)) (vectors_prod_eq_one G p) _ _ _ _ _ _ 1 hp hzmod,
have hdvdcard : p ∣ fintype.card (vectors_prod_eq_one G (n + 1)) :=
calc p ∣ card G ^ 1 : by rwa pow_one
... ∣ card G ^ (n : ℕ) : pow_dvd_pow _ n.2
... = card (vectors_prod_eq_one G (n + 1)) : hcard.symm,
have hdvdcard₂ : p ∣ card (fixed_points (multiplicative (zmod p)) (vectors_prod_eq_one G p)),
by { rw nat.dvd_iff_mod_eq_zero at hdvdcard ⊢, rwa [← hn, hmodeq] at hdvdcard },
have hcard_pos : 0 < card (fixed_points (multiplicative (zmod p)) (vectors_prod_eq_one G p)) :=
fintype.card_pos_iff.2 ⟨⟨⟨vector.repeat 1 p, one_mem_vectors_prod_eq_one _⟩,
one_mem_fixed_points_rotate _⟩⟩,
have hlt : 1 < card (fixed_points (multiplicative (zmod p)) (vectors_prod_eq_one G p)) :=
calc (1 : ℕ) < p : hp.one_lt
... ≤ _ : nat.le_of_dvd hcard_pos hdvdcard₂,
let ⟨⟨⟨⟨x, hx₁⟩, hx₂⟩, hx₃⟩, hx₄⟩ := fintype.exists_ne_of_one_lt_card hlt
⟨_, one_mem_fixed_points_rotate p⟩ in
have hx : x ≠ list.repeat (1 : G) p, from λ h, by simpa [h, vector.repeat] using hx₄,
have ∃ a, x = list.repeat a x.length := by exactI rotate_eq_self_iff_eq_repeat.1 (λ n,
have list.rotate x (n : zmod p).val = x :=
subtype.mk.inj (subtype.mk.inj (hx₃ (n : zmod p))),
by rwa [zmod.val_cast_nat, ← hx₁, rotate_mod] at this),
let ⟨a, ha⟩ := this in
⟨a, have hx1 : x.prod = 1 := hx₂,
have ha1: a ≠ 1, from λ h, hx (ha.symm ▸ h ▸ hx₁ ▸ rfl),
have a ^ p = 1, by rwa [ha, list.prod_repeat, hx₁] at hx1,
(hp.2 _ (order_of_dvd_of_pow_eq_one this)).resolve_left
(λ h, ha1 (order_of_eq_one_iff.1 h))⟩
open subgroup submonoid is_group_hom mul_action
lemma mem_fixed_points_mul_left_cosets_iff_mem_normalizer {H : subgroup G}
[fintype ((H : set G) : Type u)] {x : G} :
(x : quotient H) ∈ fixed_points H (quotient H) ↔ x ∈ normalizer H :=
⟨λ hx, have ha : ∀ {y : quotient H}, y ∈ orbit H (x : quotient H) → y = x,
from λ _, ((mem_fixed_points' _).1 hx _),
(inv_mem_iff _).1 (@mem_normalizer_fintype _ _ _ _inst_2 _ (λ n (hn : n ∈ H),
have (n⁻¹ * x)⁻¹ * x ∈ H := quotient_group.eq.1 (ha (mem_orbit _ ⟨n⁻¹, H.inv_mem hn⟩)),
show _ ∈ H, by {rw [mul_inv_rev, inv_inv] at this, convert this, rw inv_inv}
)),
λ (hx : ∀ (n : G), n ∈ H ↔ x * n * x⁻¹ ∈ H),
(mem_fixed_points' _).2 $ λ y, quotient.induction_on' y $ λ y hy, quotient_group.eq.2
(let ⟨⟨b, hb₁⟩, hb₂⟩ := hy in
have hb₂ : (b * x)⁻¹ * y ∈ H := quotient_group.eq.1 hb₂,
(inv_mem_iff H).1 $ (hx _).2 $ (mul_mem_cancel_left H (H.inv_mem hb₁)).1
$ by rw hx at hb₂;
simpa [mul_inv_rev, mul_assoc] using hb₂)⟩
def fixed_points_mul_left_cosets_equiv_quotient (H : subgroup G) [fintype (H : set G)] :
fixed_points H (quotient H) ≃
quotient (subgroup.comap ((normalizer H).subtype : normalizer H →* G) H) :=
@subtype_quotient_equiv_quotient_subtype G (normalizer H : set G) (id _) (id _) (fixed_points _ _)
(λ a, (@mem_fixed_points_mul_left_cosets_iff_mem_normalizer _ _ _ _inst_2 _).symm)
(by intros; refl)
lemma exists_subgroup_card_pow_prime [fintype G] (p : ℕ) : ∀ {n : ℕ} [hp : fact p.prime]
(hdvd : p ^ n ∣ card G), ∃ H : subgroup G, fintype.card H = p ^ n
| 0 := λ _ _, ⟨(⊥ : subgroup G), by convert card_trivial⟩
| (n+1) := λ hp hdvd,
let ⟨H, hH2⟩ := @exists_subgroup_card_pow_prime _ hp
(dvd.trans (pow_dvd_pow _ (nat.le_succ _)) hdvd) in
let ⟨s, hs⟩ := exists_eq_mul_left_of_dvd hdvd in
have hcard : card (quotient H) = s * p :=
(nat.mul_left_inj (show card H > 0, from fintype.card_pos_iff.2
⟨⟨1, H.one_mem⟩⟩)).1
(by rwa [← card_eq_card_quotient_mul_card_subgroup, hH2, hs,
pow_succ', mul_assoc, mul_comm p]),
have hm : s * p % p =
card (quotient (subgroup.comap ((normalizer H).subtype : normalizer H →* G) H)) % p :=
card_congr (fixed_points_mul_left_cosets_equiv_quotient H) ▸ hcard ▸
@card_modeq_card_fixed_points _ _ _ _ _ _ _ p _ hp hH2,
have hm' : p ∣ card (quotient (subgroup.comap ((normalizer H).subtype : normalizer H →* G) H)) :=
nat.dvd_of_mod_eq_zero
(by rwa [nat.mod_eq_zero_of_dvd (dvd_mul_left _ _), eq_comm] at hm),
let ⟨x, hx⟩ := @exists_prime_order_of_dvd_card _ (quotient_group.group _) _ _ hp hm' in
have hxcard : ∀ {f : fintype (subgroup.gpowers x)}, card (subgroup.gpowers x) = p,
from λ f, by rw [← hx, order_eq_card_gpowers]; congr,
have fintype (subgroup.comap (quotient_group.mk' (comap H.normalizer.subtype H)) (gpowers x)),
by apply_instance,
have hequiv : H ≃ (subgroup.comap ((normalizer H).subtype : normalizer H →* G) H) :=
⟨λ a, ⟨⟨a.1, le_normalizer a.2⟩, a.2⟩, λ a, ⟨a.1.1, a.2⟩,
λ ⟨_, _⟩, rfl, λ ⟨⟨_, _⟩, _⟩, rfl⟩,
-- begin proof of ∃ H : subgroup G, fintype.card H = p ^ n
⟨subgroup.map ((normalizer H).subtype) (subgroup.comap (quotient_group.mk' _) (gpowers x)),
begin
show card ↥(map H.normalizer.subtype
(comap (mk' (comap H.normalizer.subtype H)) (subgroup.gpowers x))) = p ^ (n + 1),
suffices : card ↥(subtype.val '' ((subgroup.comap (mk' (comap H.normalizer.subtype H))
(gpowers x)) : set (↥(H.normalizer)))) = p^(n+1),
{ convert this },
rw [set.card_image_of_injective
(subgroup.comap (mk' _) (gpowers x) : set (H.normalizer)) subtype.val_injective,
pow_succ', ← hH2, fintype.card_congr hequiv, ← hx, order_eq_card_gpowers,
← fintype.card_prod],
exact @fintype.card_congr _ _ (id _) (id _) (preimage_mk_equiv_subgroup_times_set _ _)
end⟩
end sylow
|
3c1256f57de79e23bd82ae25c5aecbf703c15f44 | 3446e92e64a5de7ed1f2109cfb024f83cd904c34 | /src/game/world3/level1.lean | 2fee7393da27201a75a8a8f7fd56dba7599882f3 | [] | no_license | kckennylau/natural_number_game | 019f4a5f419c9681e65234ecd124c564f9a0a246 | ad8c0adaa725975be8a9f978c8494a39311029be | refs/heads/master | 1,598,784,137,722 | 1,571,905,156,000 | 1,571,905,156,000 | 218,354,686 | 0 | 0 | null | 1,572,373,319,000 | 1,572,373,318,000 | null | UTF-8 | Lean | false | false | 1,421 | lean | import game.world2.level6 -- hide
import mynat.mul
/-
# World 3
A new import! This import gives you the definition of multiplication on your
natural numbers. It is defined by recursion, just like addition.
Here are the two new axioms:
* `mul_zero : ∀ a : mynat, a * 0 = 0`
* `mul_succ : ∀ a b : mynat, a * succ(b) = a * b + b`
In words, we define multiplication by "induction on the second variable",
with `a * 0` defined to be `0` and, if we know `a * b`, then `a` times
the number after `b` is defined to be `a * b + b`.
You can keep all the theorems you proved about addition, but
for multiplication, those two results above are you've got right now.
Like addition, we need to go for the proofs that multiplication
is commutative and associative, but as well as that we will
need to prove facts about the relationship between multiplication
and addition, for example `a * (b + c) = a * b + a * c`, so now
there is a lot more to do. Good luck!
We are given `mul_zero`, and the first thing to prove is `zero_mul`.
Like `zero_add`, we of course prove it by induction.
## World 3 Level 1 : `zero_mul`
-/
namespace mynat -- hide
/- Lemma
For all natural numbers $m$, we have
$$ 0 * m = 0. $$
-/
lemma zero_mul (m : mynat) : 0 * m = 0 :=
begin [less_leaky]
induction m with d hd,
{
rw mul_zero,
refl
},
{
rw mul_succ,
rw hd,
rw add_zero,
refl
}
end
end mynat -- hide
|
2ea492873b48895be3d92f98c962abd2fc8ddf5a | bbecf0f1968d1fba4124103e4f6b55251d08e9c4 | /src/set_theory/game/state.lean | e584092187067dd72caad5d09470f62e3f4a2cdc | [
"Apache-2.0"
] | permissive | waynemunro/mathlib | e3fd4ff49f4cb43d4a8ded59d17be407bc5ee552 | 065a70810b5480d584033f7bbf8e0409480c2118 | refs/heads/master | 1,693,417,182,397 | 1,634,644,781,000 | 1,634,644,781,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 8,404 | 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 set_theory.game.short
/-!
# Games described via "the state of the board".
We provide a simple mechanism for constructing combinatorial (pre-)games, by describing
"the state of the board", and providing an upper bound on the number of turns remaining.
## Implementation notes
We're very careful to produce a computable definition, so small games can be evaluated
using `dec_trivial`. To achieve this, I've had to rely solely on induction on natural numbers:
relying on general well-foundedness seems to be poisonous to computation?
See `set_theory/game/domineering` for an example using this construction.
-/
universe u
namespace pgame
/--
`pgame_state S` describes how to interpret `s : S` as a state of a combinatorial game.
Use `pgame.of s` or `game.of s` to construct the game.
`pgame_state.L : S → finset S` and `pgame_state.R : S → finset S` describe the states reachable
by a move by Left or Right. `pgame_state.turn_bound : S → ℕ` gives an upper bound on the number of
possible turns remaining from this state.
-/
class state (S : Type u) :=
(turn_bound : S → ℕ)
(L : S → finset S)
(R : S → finset S)
(left_bound : ∀ {s t : S} (m : t ∈ L s), turn_bound t < turn_bound s)
(right_bound : ∀ {s t : S} (m : t ∈ R s), turn_bound t < turn_bound s)
open state
variables {S : Type u} [state S]
lemma turn_bound_ne_zero_of_left_move {s t : S} (m : t ∈ L s) : turn_bound s ≠ 0 :=
begin
intro h,
have t := state.left_bound m,
rw h at t,
exact nat.not_succ_le_zero _ t,
end
lemma turn_bound_ne_zero_of_right_move {s t : S} (m : t ∈ R s) : turn_bound s ≠ 0 :=
begin
intro h,
have t := state.right_bound m,
rw h at t,
exact nat.not_succ_le_zero _ t,
end
lemma turn_bound_of_left {s t : S} (m : t ∈ L s) (n : ℕ) (h : turn_bound s ≤ n + 1) :
turn_bound t ≤ n :=
nat.le_of_lt_succ (nat.lt_of_lt_of_le (left_bound m) h)
lemma turn_bound_of_right {s t : S} (m : t ∈ R s) (n : ℕ) (h : turn_bound s ≤ n + 1) :
turn_bound t ≤ n :=
nat.le_of_lt_succ (nat.lt_of_lt_of_le (right_bound m) h)
/--
Construct a `pgame` from a state and a (not necessarily optimal) bound on the number of
turns remaining.
-/
def of_aux : Π (n : ℕ) (s : S) (h : turn_bound s ≤ n), pgame
| 0 s h := pgame.mk {t // t ∈ L s} {t // t ∈ R s}
(λ t, begin exfalso, exact turn_bound_ne_zero_of_left_move t.2 (nonpos_iff_eq_zero.mp h) end)
(λ t, begin exfalso, exact turn_bound_ne_zero_of_right_move t.2 (nonpos_iff_eq_zero.mp h) end)
| (n+1) s h :=
pgame.mk {t // t ∈ L s} {t // t ∈ R s}
(λ t, of_aux n t (turn_bound_of_left t.2 n h))
(λ t, of_aux n t (turn_bound_of_right t.2 n h))
/-- Two different (valid) turn bounds give equivalent games. -/
def of_aux_relabelling : Π (s : S) (n m : ℕ) (hn : turn_bound s ≤ n) (hm : turn_bound s ≤ m),
relabelling (of_aux n s hn) (of_aux m s hm)
| s 0 0 hn hm :=
begin
dsimp [pgame.of_aux],
fsplit, refl, refl,
{ intro i, dsimp at i, exfalso,
exact turn_bound_ne_zero_of_left_move i.2 (nonpos_iff_eq_zero.mp hn) },
{ intro j, dsimp at j, exfalso,
exact turn_bound_ne_zero_of_right_move j.2 (nonpos_iff_eq_zero.mp hm) }
end
| s 0 (m+1) hn hm :=
begin
dsimp [pgame.of_aux],
fsplit, refl, refl,
{ intro i, dsimp at i, exfalso,
exact turn_bound_ne_zero_of_left_move i.2 (nonpos_iff_eq_zero.mp hn) },
{ intro j, dsimp at j, exfalso,
exact turn_bound_ne_zero_of_right_move j.2 (nonpos_iff_eq_zero.mp hn) }
end
| s (n+1) 0 hn hm :=
begin
dsimp [pgame.of_aux],
fsplit, refl, refl,
{ intro i, dsimp at i, exfalso,
exact turn_bound_ne_zero_of_left_move i.2 (nonpos_iff_eq_zero.mp hm) },
{ intro j, dsimp at j, exfalso,
exact turn_bound_ne_zero_of_right_move j.2 (nonpos_iff_eq_zero.mp hm) }
end
| s (n+1) (m+1) hn hm :=
begin
dsimp [pgame.of_aux],
fsplit, refl, refl,
{ intro i,
apply of_aux_relabelling, },
{ intro j,
apply of_aux_relabelling, }
end
/-- Construct a combinatorial `pgame` from a state. -/
def of (s : S) : pgame := of_aux (turn_bound s) s (refl _)
/--
The equivalence between `left_moves` for a `pgame` constructed using `of_aux _ s _`, and `L s`.
-/
def left_moves_of_aux (n : ℕ) {s : S} (h : turn_bound s ≤ n) :
left_moves (of_aux n s h) ≃ {t // t ∈ L s} :=
by induction n; refl
/--
The equivalence between `left_moves` for a `pgame` constructed using `of s`, and `L s`.
-/
def left_moves_of (s : S) : left_moves (of s) ≃ {t // t ∈ L s} :=
left_moves_of_aux _ _
/--
The equivalence between `right_moves` for a `pgame` constructed using `of_aux _ s _`, and `R s`.
-/
def right_moves_of_aux (n : ℕ) {s : S} (h : turn_bound s ≤ n) :
right_moves (of_aux n s h) ≃ {t // t ∈ R s} :=
by induction n; refl
/-- The equivalence between `right_moves` for a `pgame` constructed using `of s`, and `R s`. -/
def right_moves_of (s : S) : right_moves (of s) ≃ {t // t ∈ R s} :=
right_moves_of_aux _ _
/--
The relabelling showing `move_left` applied to a game constructed using `of_aux`
has itself been constructed using `of_aux`.
-/
def relabelling_move_left_aux (n : ℕ) {s : S} (h : turn_bound s ≤ n)
(t : left_moves (of_aux n s h)) :
relabelling
(move_left (of_aux n s h) t)
(of_aux (n-1) (((left_moves_of_aux n h) t) : S)
((turn_bound_of_left ((left_moves_of_aux n h) t).2 (n-1)
(nat.le_trans h le_sub_add)))) :=
begin
induction n,
{ have t' := (left_moves_of_aux 0 h) t,
exfalso, exact turn_bound_ne_zero_of_left_move t'.2 (nonpos_iff_eq_zero.mp h), },
{ refl },
end
/--
The relabelling showing `move_left` applied to a game constructed using `of`
has itself been constructed using `of`.
-/
def relabelling_move_left (s : S) (t : left_moves (of s)) :
relabelling
(move_left (of s) t)
(of (((left_moves_of s).to_fun t) : S)) :=
begin
transitivity,
apply relabelling_move_left_aux,
apply of_aux_relabelling,
end
/--
The relabelling showing `move_right` applied to a game constructed using `of_aux`
has itself been constructed using `of_aux`.
-/
def relabelling_move_right_aux (n : ℕ) {s : S} (h : turn_bound s ≤ n)
(t : right_moves (of_aux n s h)) :
relabelling
(move_right (of_aux n s h) t)
(of_aux (n-1) (((right_moves_of_aux n h) t) : S)
((turn_bound_of_right ((right_moves_of_aux n h) t).2 (n-1)
(nat.le_trans h le_sub_add)))) :=
begin
induction n,
{ have t' := (right_moves_of_aux 0 h) t,
exfalso, exact turn_bound_ne_zero_of_right_move t'.2 (nonpos_iff_eq_zero.mp h), },
{ refl },
end
/--
The relabelling showing `move_right` applied to a game constructed using `of`
has itself been constructed using `of`.
-/
def relabelling_move_right (s : S) (t : right_moves (of s)) :
relabelling
(move_right (of s) t)
(of (((right_moves_of s).to_fun t) : S)) :=
begin
transitivity,
apply relabelling_move_right_aux,
apply of_aux_relabelling,
end
instance fintype_left_moves_of_aux (n : ℕ) (s : S) (h : turn_bound s ≤ n) :
fintype (left_moves (of_aux n s h)) :=
begin
apply fintype.of_equiv _ (left_moves_of_aux _ _).symm,
apply_instance,
end
instance fintype_right_moves_of_aux (n : ℕ) (s : S) (h : turn_bound s ≤ n) :
fintype (right_moves (of_aux n s h)) :=
begin
apply fintype.of_equiv _ (right_moves_of_aux _ _).symm,
apply_instance,
end
instance short_of_aux : Π (n : ℕ) {s : S} (h : turn_bound s ≤ n), short (of_aux n s h)
| 0 s h :=
short.mk'
(λ i, begin
have i := (left_moves_of_aux _ _).to_fun i,
exfalso,
exact turn_bound_ne_zero_of_left_move i.2 (nonpos_iff_eq_zero.mp h),
end)
(λ j, begin
have j := (right_moves_of_aux _ _).to_fun j,
exfalso,
exact turn_bound_ne_zero_of_right_move j.2 (nonpos_iff_eq_zero.mp h),
end)
| (n+1) s h :=
short.mk'
(λ i, short_of_relabelling (relabelling_move_left_aux (n+1) h i).symm (short_of_aux n _))
(λ j, short_of_relabelling (relabelling_move_right_aux (n+1) h j).symm (short_of_aux n _))
instance short_of (s : S) : short (of s) :=
begin
dsimp [pgame.of],
apply_instance
end
end pgame
namespace game
/-- Construct a combinatorial `game` from a state. -/
def of {S : Type u} [pgame.state S] (s : S) : game := ⟦pgame.of s⟧
end game
|
d0e0d96dc70604b4f3887c080e741be81d96fc49 | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/group_theory/perm/basic.lean | e3ee863f0aba069e5e6203041dced4e760ab48bb | [
"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 | 15,631 | 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, Mario Carneiro
-/
import algebra.group.pi
import algebra.group_power.lemmas
import algebra.group.prod
import logic.function.iterate
/-!
# The group of permutations (self-equivalences) of a type `α`
This file defines the `group` structure on `equiv.perm α`.
-/
universes u v
namespace equiv
variables {α : Type u} {β : Type v}
namespace perm
instance perm_group : group (perm α) :=
{ mul := λ f g, equiv.trans g f,
one := equiv.refl α,
inv := equiv.symm,
mul_assoc := λ f g h, (trans_assoc _ _ _).symm,
one_mul := trans_refl,
mul_one := refl_trans,
mul_left_inv := self_trans_symm }
/-- The permutation of a type is equivalent to the units group of the endomorphisms monoid of this
type. -/
@[simps] def equiv_units_End : perm α ≃* units (function.End α) :=
{ to_fun := λ e, ⟨e, e.symm, e.self_comp_symm, e.symm_comp_self⟩,
inv_fun := λ u, ⟨(u : function.End α), (↑u⁻¹ : function.End α), congr_fun u.inv_val,
congr_fun u.val_inv⟩,
left_inv := λ e, ext $ λ x, rfl,
right_inv := λ u, units.ext rfl,
map_mul' := λ e₁ e₂, rfl }
/-- Lift a monoid homomorphism `f : G →* function.End α` to a monoid homomorphism
`f : G →* equiv.perm α`. -/
@[simps] def _root_.monoid_hom.to_hom_perm {G : Type*} [group G] (f : G →* function.End α) :
G →* perm α :=
equiv_units_End.symm.to_monoid_hom.comp f.to_hom_units
theorem mul_apply (f g : perm α) (x) : (f * g) x = f (g x) :=
equiv.trans_apply _ _ _
theorem one_apply (x) : (1 : perm α) x = x := rfl
@[simp] lemma inv_apply_self (f : perm α) (x) : f⁻¹ (f x) = x := f.symm_apply_apply x
@[simp] lemma apply_inv_self (f : perm α) (x) : f (f⁻¹ x) = x := f.apply_symm_apply x
lemma one_def : (1 : perm α) = equiv.refl α := rfl
lemma mul_def (f g : perm α) : f * g = g.trans f := rfl
lemma inv_def (f : perm α) : f⁻¹ = f.symm := rfl
@[simp] lemma coe_mul (f g : perm α) : ⇑(f * g) = f ∘ g := rfl
@[simp] lemma coe_one : ⇑(1 : perm α) = id := rfl
lemma eq_inv_iff_eq {f : perm α} {x y : α} : x = f⁻¹ y ↔ f x = y := f.eq_symm_apply
lemma inv_eq_iff_eq {f : perm α} {x y : α} : f⁻¹ x = y ↔ x = f y := f.symm_apply_eq
lemma zpow_apply_comm {α : Type*} (σ : perm α) (m n : ℤ) {x : α} :
(σ ^ m) ((σ ^ n) x) = (σ ^ n) ((σ ^ m) x) :=
by rw [←equiv.perm.mul_apply, ←equiv.perm.mul_apply, zpow_mul_comm]
@[simp] lemma iterate_eq_pow (f : perm α) : ∀ n, f^[n] = ⇑(f ^ n)
| 0 := rfl
| (n + 1) := by { rw [function.iterate_succ, pow_add, iterate_eq_pow], refl }
/-! Lemmas about mixing `perm` with `equiv`. Because we have multiple ways to express
`equiv.refl`, `equiv.symm`, and `equiv.trans`, we want simp lemmas for every combination.
The assumption made here is that if you're using the group structure, you want to preserve it after
simp. -/
@[simp] lemma trans_one {α : Sort*} {β : Type*} (e : α ≃ β) : e.trans (1 : perm β) = e :=
equiv.trans_refl e
@[simp] lemma mul_refl (e : perm α) : e * equiv.refl α = e := equiv.trans_refl e
@[simp] lemma one_symm : (1 : perm α).symm = 1 := equiv.refl_symm
@[simp] lemma refl_inv : (equiv.refl α : perm α)⁻¹ = 1 := equiv.refl_symm
@[simp] lemma one_trans {α : Type*} {β : Sort*} (e : α ≃ β) : (1 : perm α).trans e = e :=
equiv.refl_trans e
@[simp] lemma refl_mul (e : perm α) : equiv.refl α * e = e := equiv.refl_trans e
@[simp] lemma inv_trans_self (e : perm α) : e⁻¹.trans e = 1 := equiv.symm_trans_self e
@[simp] lemma mul_symm (e : perm α) : e * e.symm = 1 := equiv.symm_trans_self e
@[simp] lemma self_trans_inv (e : perm α) : e.trans e⁻¹ = 1 := equiv.self_trans_symm e
@[simp] lemma symm_mul (e : perm α) : e.symm * e = 1 := equiv.self_trans_symm e
/-! Lemmas about `equiv.perm.sum_congr` re-expressed via the group structure. -/
@[simp] lemma sum_congr_mul {α β : Type*} (e : perm α) (f : perm β) (g : perm α) (h : perm β) :
sum_congr e f * sum_congr g h = sum_congr (e * g) (f * h) :=
sum_congr_trans g h e f
@[simp] lemma sum_congr_inv {α β : Type*} (e : perm α) (f : perm β) :
(sum_congr e f)⁻¹ = sum_congr e⁻¹ f⁻¹ :=
sum_congr_symm e f
@[simp] lemma sum_congr_one {α β : Type*} :
sum_congr (1 : perm α) (1 : perm β) = 1 :=
sum_congr_refl
/-- `equiv.perm.sum_congr` as a `monoid_hom`, with its two arguments bundled into a single `prod`.
This is particularly useful for its `monoid_hom.range` projection, which is the subgroup of
permutations which do not exchange elements between `α` and `β`. -/
@[simps]
def sum_congr_hom (α β : Type*) :
perm α × perm β →* perm (α ⊕ β) :=
{ to_fun := λ a, sum_congr a.1 a.2,
map_one' := sum_congr_one,
map_mul' := λ a b, (sum_congr_mul _ _ _ _).symm}
lemma sum_congr_hom_injective {α β : Type*} :
function.injective (sum_congr_hom α β) :=
begin
rintros ⟨⟩ ⟨⟩ h,
rw prod.mk.inj_iff,
split; ext i,
{ simpa using equiv.congr_fun h (sum.inl i), },
{ simpa using equiv.congr_fun h (sum.inr i), },
end
@[simp] lemma sum_congr_swap_one {α β : Type*} [decidable_eq α] [decidable_eq β] (i j : α) :
sum_congr (equiv.swap i j) (1 : perm β) = equiv.swap (sum.inl i) (sum.inl j) :=
sum_congr_swap_refl i j
@[simp] lemma sum_congr_one_swap {α β : Type*} [decidable_eq α] [decidable_eq β] (i j : β) :
sum_congr (1 : perm α) (equiv.swap i j) = equiv.swap (sum.inr i) (sum.inr j) :=
sum_congr_refl_swap i j
/-! Lemmas about `equiv.perm.sigma_congr_right` re-expressed via the group structure. -/
@[simp] lemma sigma_congr_right_mul {α : Type*} {β : α → Type*}
(F : Π a, perm (β a)) (G : Π a, perm (β a)) :
sigma_congr_right F * sigma_congr_right G = sigma_congr_right (F * G) :=
sigma_congr_right_trans G F
@[simp] lemma sigma_congr_right_inv {α : Type*} {β : α → Type*} (F : Π a, perm (β a)) :
(sigma_congr_right F)⁻¹ = sigma_congr_right (λ a, (F a)⁻¹) :=
sigma_congr_right_symm F
@[simp] lemma sigma_congr_right_one {α : Type*} {β : α → Type*} :
(sigma_congr_right (1 : Π a, equiv.perm $ β a)) = 1 :=
sigma_congr_right_refl
/-- `equiv.perm.sigma_congr_right` as a `monoid_hom`.
This is particularly useful for its `monoid_hom.range` projection, which is the subgroup of
permutations which do not exchange elements between fibers. -/
@[simps]
def sigma_congr_right_hom {α : Type*} (β : α → Type*) :
(Π a, perm (β a)) →* perm (Σ a, β a) :=
{ to_fun := sigma_congr_right,
map_one' := sigma_congr_right_one,
map_mul' := λ a b, (sigma_congr_right_mul _ _).symm }
lemma sigma_congr_right_hom_injective {α : Type*} {β : α → Type*} :
function.injective (sigma_congr_right_hom β) :=
begin
intros x y h,
ext a b,
simpa using equiv.congr_fun h ⟨a, b⟩,
end
/-- `equiv.perm.subtype_congr` as a `monoid_hom`. -/
@[simps] def subtype_congr_hom (p : α → Prop) [decidable_pred p] :
(perm {a // p a}) × (perm {a // ¬ p a}) →* perm α :=
{ to_fun := λ pair, perm.subtype_congr pair.fst pair.snd,
map_one' := perm.subtype_congr.refl,
map_mul' := λ _ _, (perm.subtype_congr.trans _ _ _ _).symm }
lemma subtype_congr_hom_injective (p : α → Prop) [decidable_pred p] :
function.injective (subtype_congr_hom p) :=
begin
rintros ⟨⟩ ⟨⟩ h,
rw prod.mk.inj_iff,
split;
ext i;
simpa using equiv.congr_fun h i
end
/-- If `e` is also a permutation, we can write `perm_congr`
completely in terms of the group structure. -/
@[simp] lemma perm_congr_eq_mul (e p : perm α) :
e.perm_congr p = e * p * e⁻¹ := rfl
section extend_domain
/-! Lemmas about `equiv.perm.extend_domain` re-expressed via the group structure. -/
variables (e : perm α) {p : β → Prop} [decidable_pred p] (f : α ≃ subtype p)
@[simp] lemma extend_domain_one : extend_domain 1 f = 1 :=
extend_domain_refl f
@[simp] lemma extend_domain_inv : (e.extend_domain f)⁻¹ = e⁻¹.extend_domain f := rfl
@[simp] lemma extend_domain_mul (e e' : perm α) :
(e.extend_domain f) * (e'.extend_domain f) = (e * e').extend_domain f :=
extend_domain_trans _ _ _
/-- `extend_domain` as a group homomorphism -/
@[simps] def extend_domain_hom : perm α →* perm β :=
{ to_fun := λ e, extend_domain e f,
map_one' := extend_domain_one f,
map_mul' := λ e e', (extend_domain_mul f e e').symm }
lemma extend_domain_hom_injective : function.injective (extend_domain_hom f) :=
(injective_iff_map_eq_one (extend_domain_hom f)).mpr (λ e he, ext (λ x, f.injective (subtype.ext
((extend_domain_apply_image e f x).symm.trans (ext_iff.mp he (f x))))))
@[simp] lemma extend_domain_eq_one_iff {e : perm α} {f : α ≃ subtype p} :
e.extend_domain f = 1 ↔ e = 1 :=
(injective_iff_map_eq_one' (extend_domain_hom f)).mp (extend_domain_hom_injective f) e
end extend_domain
/-- If the permutation `f` fixes the subtype `{x // p x}`, then this returns the permutation
on `{x // p x}` induced by `f`. -/
def subtype_perm (f : perm α) {p : α → Prop} (h : ∀ x, p x ↔ p (f x)) : perm {x // p x} :=
⟨λ x, ⟨f x, (h _).1 x.2⟩, λ x, ⟨f⁻¹ x, (h (f⁻¹ x)).2 $ by simpa using x.2⟩,
λ _, by simp only [perm.inv_apply_self, subtype.coe_eta, subtype.coe_mk],
λ _, by simp only [perm.apply_inv_self, subtype.coe_eta, subtype.coe_mk]⟩
@[simp] lemma subtype_perm_apply (f : perm α) {p : α → Prop} (h : ∀ x, p x ↔ p (f x))
(x : {x // p x}) : subtype_perm f h x = ⟨f x, (h _).1 x.2⟩ := rfl
@[simp] lemma subtype_perm_one (p : α → Prop) (h : ∀ x, p x ↔ p ((1 : perm α) x)) :
@subtype_perm α 1 p h = 1 :=
equiv.ext $ λ ⟨_, _⟩, rfl
/-- The inclusion map of permutations on a subtype of `α` into permutations of `α`,
fixing the other points. -/
def of_subtype {p : α → Prop} [decidable_pred p] : perm (subtype p) →* perm α :=
{ to_fun := λ f, extend_domain f (equiv.refl (subtype p)),
map_one' := equiv.perm.extend_domain_one _,
map_mul' := λ f g, (equiv.perm.extend_domain_mul _ f g).symm, }
lemma of_subtype_subtype_perm {f : perm α} {p : α → Prop} [decidable_pred p]
(h₁ : ∀ x, p x ↔ p (f x)) (h₂ : ∀ x, f x ≠ x → p x) :
of_subtype (subtype_perm f h₁) = f :=
equiv.ext $ λ x, begin
by_cases hx : p x,
{ exact (subtype_perm f h₁).extend_domain_apply_subtype _ hx, },
{ rw [of_subtype, monoid_hom.coe_mk, equiv.perm.extend_domain_apply_not_subtype],
{ exact not_not.mp (λ h, hx (h₂ x (ne.symm h))), },
{ exact hx, }, }
end
lemma of_subtype_apply_of_mem {p : α → Prop} [decidable_pred p]
(f : perm (subtype p)) {x : α} (hx : p x) :
of_subtype f x = f ⟨x, hx⟩ := extend_domain_apply_subtype f _ hx
@[simp] lemma of_subtype_apply_coe {p : α → Prop} [decidable_pred p]
(f : perm (subtype p)) (x : subtype p) :
of_subtype f x = f x :=
subtype.cases_on x $ λ _, of_subtype_apply_of_mem f
lemma of_subtype_apply_of_not_mem {p : α → Prop} [decidable_pred p]
(f : perm (subtype p)) {x : α} (hx : ¬ p x) :
of_subtype f x = x := extend_domain_apply_not_subtype f (equiv.refl (subtype p)) hx
lemma mem_iff_of_subtype_apply_mem {p : α → Prop} [decidable_pred p]
(f : perm (subtype p)) (x : α) :
p x ↔ p ((of_subtype f : α → α) x) :=
if h : p x then
by simpa only [h, true_iff, monoid_hom.coe_mk, of_subtype_apply_of_mem f h] using (f ⟨x, h⟩).2
else by simp [h, of_subtype_apply_of_not_mem f h]
@[simp] lemma subtype_perm_of_subtype {p : α → Prop} [decidable_pred p] (f : perm (subtype p)) :
subtype_perm (of_subtype f) (mem_iff_of_subtype_apply_mem f) = f :=
equiv.ext $ λ ⟨x, hx⟩,
subtype.coe_injective (of_subtype_apply_of_mem f hx)
@[simp] lemma default_perm {n : Type*} : (default : perm n) = 1 := rfl
/-- Permutations on a subtype are equivalent to permutations on the original type that fix pointwise
the rest. -/
@[simps] protected def subtype_equiv_subtype_perm (p : α → Prop) [decidable_pred p] :
perm (subtype p) ≃ {f : perm α // ∀ a, ¬p a → f a = a} :=
{ to_fun := λ f, ⟨f.of_subtype, λ a, f.of_subtype_apply_of_not_mem⟩,
inv_fun := λ f, (f : perm α).subtype_perm
(λ a, ⟨decidable.not_imp_not.1 $ λ hfa, (f.val.injective (f.prop _ hfa) ▸ hfa),
decidable.not_imp_not.1 $ λ ha hfa, ha $ f.prop a ha ▸ hfa⟩),
left_inv := equiv.perm.subtype_perm_of_subtype,
right_inv := λ f,
subtype.ext (equiv.perm.of_subtype_subtype_perm _ $ λ a, not.decidable_imp_symm $ f.prop a) }
lemma subtype_equiv_subtype_perm_apply_of_mem {α : Type*} {p : α → Prop}
[decidable_pred p] (f : perm (subtype p)) {a : α} (h : p a) :
perm.subtype_equiv_subtype_perm p f a = f ⟨a, h⟩ :=
f.of_subtype_apply_of_mem h
lemma subtype_equiv_subtype_perm_apply_of_not_mem {α : Type*} {p : α → Prop}
[decidable_pred p] (f : perm (subtype p)) {a : α} (h : ¬ p a) :
perm.subtype_equiv_subtype_perm p f a = a :=
f.of_subtype_apply_of_not_mem h
end perm
section swap
variables [decidable_eq α]
@[simp] lemma swap_inv (x y : α) : (swap x y)⁻¹ = swap x y := rfl
@[simp] lemma swap_mul_self (i j : α) : swap i j * swap i j = 1 := swap_swap i j
lemma swap_mul_eq_mul_swap (f : perm α) (x y : α) : swap x y * f = f * swap (f⁻¹ x) (f⁻¹ y) :=
equiv.ext $ λ z, begin
simp only [perm.mul_apply, swap_apply_def],
split_ifs;
simp only [perm.apply_inv_self, *, perm.eq_inv_iff_eq, eq_self_iff_true, not_true] at *
end
lemma mul_swap_eq_swap_mul (f : perm α) (x y : α) : f * swap x y = swap (f x) (f y) * f :=
by rw [swap_mul_eq_mul_swap, perm.inv_apply_self, perm.inv_apply_self]
lemma swap_apply_apply (f : perm α) (x y : α) : swap (f x) (f y) = f * swap x y * f⁻¹ :=
by rw [mul_swap_eq_swap_mul, mul_inv_cancel_right]
/-- Left-multiplying a permutation with `swap i j` twice gives the original permutation.
This specialization of `swap_mul_self` is useful when using cosets of permutations.
-/
@[simp]
lemma swap_mul_self_mul (i j : α) (σ : perm α) : equiv.swap i j * (equiv.swap i j * σ) = σ :=
by rw [←mul_assoc, swap_mul_self, one_mul]
/-- Right-multiplying a permutation with `swap i j` twice gives the original permutation.
This specialization of `swap_mul_self` is useful when using cosets of permutations.
-/
@[simp]
lemma mul_swap_mul_self (i j : α) (σ : perm α) : (σ * equiv.swap i j) * equiv.swap i j = σ :=
by rw [mul_assoc, swap_mul_self, mul_one]
/-- A stronger version of `mul_right_injective` -/
@[simp]
lemma swap_mul_involutive (i j : α) : function.involutive ((*) (equiv.swap i j)) :=
swap_mul_self_mul i j
/-- A stronger version of `mul_left_injective` -/
@[simp]
lemma mul_swap_involutive (i j : α) : function.involutive (* (equiv.swap i j)) :=
mul_swap_mul_self i j
@[simp] lemma swap_eq_one_iff {i j : α} : swap i j = (1 : perm α) ↔ i = j :=
swap_eq_refl_iff
lemma swap_mul_eq_iff {i j : α} {σ : perm α} : swap i j * σ = σ ↔ i = j :=
⟨(assume h, have swap_id : swap i j = 1 := mul_right_cancel (trans h (one_mul σ).symm),
by {rw [←swap_apply_right i j, swap_id], refl}),
(assume h, by erw [h, swap_self, one_mul])⟩
lemma mul_swap_eq_iff {i j : α} {σ : perm α} : σ * swap i j = σ ↔ i = j :=
⟨(assume h, have swap_id : swap i j = 1 := mul_left_cancel (trans h (one_mul σ).symm),
by {rw [←swap_apply_right i j, swap_id], refl}),
(assume h, by erw [h, swap_self, mul_one])⟩
lemma swap_mul_swap_mul_swap {x y z : α} (hwz: x ≠ y) (hxz : x ≠ z) :
swap y z * swap x y * swap y z = swap z x :=
equiv.ext $ λ n, by { simp only [swap_apply_def, perm.mul_apply], split_ifs; cc }
end swap
end equiv
|
db148556a91eaad7fbe94eb98d22cafbfd06c136 | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /tests/lean/run/evalInit.lean | 685297991bdf70626831fdb77c1c1ae62c159d99 | [
"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 | 78 | lean | #eval show IO _ from do
return RandomGen.next (← IO.stdGenRef.get) |>.fst
|
cd72000e3b705835012b9f53969f90477f3f987a | 968e2f50b755d3048175f176376eff7139e9df70 | /examples/prop_logic_theory/unnamed_2121.lean | 1c04c93823c7fd69d157ca8d626d987ab4d1d284 | [] | no_license | gihanmarasingha/mth1001_sphinx | 190a003269ba5e54717b448302a27ca26e31d491 | 05126586cbf5786e521be1ea2ef5b4ba3c44e74a | refs/heads/master | 1,672,913,933,677 | 1,604,516,583,000 | 1,604,516,583,000 | 309,245,750 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 608 | lean | variables {p q : Prop}
-- BEGIN
example : (¬p ∨ q) → (p → q) :=
begin
intros h₁ h₂, -- Assume `h₁ : ¬p ∨ q`. Assume `h₂ : p`. It suffices to prove `q`.
-- By or elim. on `h₁`, it suffices to 1. assume `h₃ : ¬p` and derive `q` and 2. assume `h₄ : q` and derive `q`
cases h₁ with h₃ h₄,
{ exfalso, -- By false elimination, it suffices to prove `false`.
show false, from h₃ h₂, }, -- We show false by false introduction on `h₃` and `h₂`.
{ show q, from h₄, }, -- We show `q` by reiteration on `h₄`.
end
-- END |
804dd0f588c4ddbd55fffa2592599cca1bb74052 | 75db7e3219bba2fbf41bf5b905f34fcb3c6ca3f2 | /library/theories/analysis/normed_space.lean | bd114ae5e1224b1c2bde485b923ea0799cacd38b | [
"Apache-2.0"
] | permissive | jroesch/lean | 30ef0860fa905d35b9ad6f76de1a4f65c9af6871 | 3de4ec1a6ce9a960feb2a48eeea8b53246fa34f2 | refs/heads/master | 1,586,090,835,348 | 1,455,142,203,000 | 1,455,142,277,000 | 51,536,958 | 1 | 0 | null | 1,455,215,811,000 | 1,455,215,811,000 | null | UTF-8 | Lean | false | false | 8,325 | lean | /-
Copyright (c) 2015 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Jeremy Avigad
Normed spaces.
-/
import algebra.module .metric_space
open real nat classical
noncomputable theory
structure has_norm [class] (M : Type) : Type :=
(norm : M → ℝ)
namespace analysis
definition norm {M : Type} [has_normM : has_norm M] (v : M) : ℝ := has_norm.norm v
notation `∥`v`∥` := norm v
end analysis
-- where is the right place to put this?
structure real_vector_space [class] (V : Type) extends vector_space ℝ V
structure normed_vector_space [class] (V : Type) extends real_vector_space V, has_norm V :=
(norm_zero : norm zero = 0)
(eq_zero_of_norm_eq_zero : ∀ u : V, norm u = 0 → u = zero)
(norm_triangle : ∀ u v, norm (add u v) ≤ norm u + norm v)
(norm_smul : ∀ (a : ℝ) (v : V), norm (smul a v) = abs a * norm v)
namespace analysis
variable {V : Type}
variable [normed_vector_space V]
proposition norm_zero : ∥ (0 : V) ∥ = 0 := !normed_vector_space.norm_zero
proposition eq_zero_of_norm_eq_zero {u : V} (H : ∥ u ∥ = 0) : u = 0 :=
!normed_vector_space.eq_zero_of_norm_eq_zero H
proposition norm_triangle (u v : V) : ∥ u + v ∥ ≤ ∥ u ∥ + ∥ v ∥ :=
!normed_vector_space.norm_triangle
proposition norm_smul (a : ℝ) (v : V) : ∥ a • v ∥ = abs a * ∥ v ∥ :=
!normed_vector_space.norm_smul
proposition norm_neg (v : V) : ∥ -v ∥ = ∥ v ∥ :=
have abs (1 : ℝ) = 1, from abs_of_nonneg zero_le_one,
by+ rewrite [-@neg_one_smul ℝ V, norm_smul, abs_neg, this, one_mul]
end analysis
section
open analysis
variable {V : Type}
variable [normed_vector_space V]
private definition nvs_dist [reducible] (u v : V) := ∥ u - v ∥
private lemma nvs_dist_self (u : V) : nvs_dist u u = 0 :=
by rewrite [↑nvs_dist, sub_self, norm_zero]
private lemma eq_of_nvs_dist_eq_zero (u v : V) (H : nvs_dist u v = 0) : u = v :=
have u - v = 0, from eq_zero_of_norm_eq_zero H,
eq_of_sub_eq_zero this
private lemma nvs_dist_triangle (u v w : V) : nvs_dist u w ≤ nvs_dist u v + nvs_dist v w :=
calc
nvs_dist u w = ∥ (u - v) + (v - w) ∥ : by rewrite [↑nvs_dist, *sub_eq_add_neg, add.assoc,
neg_add_cancel_left]
... ≤ ∥ u - v ∥ + ∥ v - w ∥ : norm_triangle
private lemma nvs_dist_comm (u v : V) : nvs_dist u v = nvs_dist v u :=
by rewrite [↑nvs_dist, -norm_neg, neg_sub]
definition normed_vector_space_to_metric_space [reducible] [trans_instance]
(V : Type) [nvsV : normed_vector_space V] :
metric_space V :=
⦃ metric_space,
dist := nvs_dist,
dist_self := nvs_dist_self,
eq_of_dist_eq_zero := eq_of_nvs_dist_eq_zero,
dist_comm := nvs_dist_comm,
dist_triangle := nvs_dist_triangle
⦄
open nat
proposition converges_to_seq_norm_elim {X : ℕ → V} {x : V} (H : X ⟶ x in ℕ) :
∀ {ε : ℝ}, ε > 0 → ∃ N₁ : ℕ, ∀ {n : ℕ}, n ≥ N₁ → ∥ X n - x ∥ < ε := H
proposition dist_eq_norm_sub (u v : V) : dist u v = ∥ u - v ∥ := rfl
proposition norm_eq_dist_zero (u : V) : ∥ u ∥ = dist u 0 :=
by rewrite [dist_eq_norm_sub, sub_zero]
proposition norm_nonneg (u : V) : ∥ u ∥ ≥ 0 :=
by rewrite norm_eq_dist_zero; apply !dist_nonneg
end
structure banach_space [class] (V : Type) extends nvsV : normed_vector_space V :=
(complete : ∀ X, @analysis.cauchy V (@normed_vector_space_to_metric_space V nvsV) X →
@analysis.converges_seq V (@normed_vector_space_to_metric_space V nvsV) X)
definition banach_space_to_metric_space [reducible] [trans_instance]
(V : Type) [bsV : banach_space V] :
complete_metric_space V :=
⦃ complete_metric_space, normed_vector_space_to_metric_space V,
complete := banach_space.complete
⦄
namespace analysis
variable {V : Type}
variable [normed_vector_space V]
variables {X Y : ℕ → V}
variables {x y : V}
proposition add_converges_to_seq (HX : X ⟶ x in ℕ) (HY : Y ⟶ y in ℕ) :
(λ n, X n + Y n) ⟶ x + y in ℕ :=
take ε : ℝ, suppose ε > 0,
have e2pos : ε / 2 > 0, from div_pos_of_pos_of_pos `ε > 0` two_pos,
obtain (N₁ : ℕ) (HN₁ : ∀ {n}, n ≥ N₁ → ∥ X n - x ∥ < ε / 2),
from converges_to_seq_norm_elim HX e2pos,
obtain (N₂ : ℕ) (HN₂ : ∀ {n}, n ≥ N₂ → ∥ Y n - y ∥ < ε / 2),
from converges_to_seq_norm_elim HY e2pos,
let N := max N₁ N₂ in
exists.intro N
(take n,
suppose n ≥ N,
have ngtN₁ : n ≥ N₁, from nat.le_trans !le_max_left `n ≥ N`,
have ngtN₂ : n ≥ N₂, from nat.le_trans !le_max_right `n ≥ N`,
show ∥ (X n + Y n) - (x + y) ∥ < ε, from calc
∥ (X n + Y n) - (x + y) ∥
= ∥ (X n - x) + (Y n - y) ∥ : by rewrite [sub_add_eq_sub_sub, *sub_eq_add_neg,
*add.assoc, add.left_comm (-x)]
... ≤ ∥ X n - x ∥ + ∥ Y n - y ∥ : norm_triangle
... < ε / 2 + ε / 2 : add_lt_add (HN₁ ngtN₁) (HN₂ ngtN₂)
... = ε : add_halves)
private lemma smul_converges_to_seq_aux {c : ℝ} (cnz : c ≠ 0) (HX : X ⟶ x in ℕ) :
(λ n, c • X n) ⟶ c • x in ℕ :=
take ε : ℝ, suppose ε > 0,
have abscpos : abs c > 0, from abs_pos_of_ne_zero cnz,
have epos : ε / abs c > 0, from div_pos_of_pos_of_pos `ε > 0` abscpos,
obtain N (HN : ∀ {n}, n ≥ N → norm (X n - x) < ε / abs c), from converges_to_seq_norm_elim HX epos,
exists.intro N
(take n,
suppose n ≥ N,
have H : norm (X n - x) < ε / abs c, from HN this,
show norm (c • X n - c • x) < ε, from calc
norm (c • X n - c • x)
= abs c * norm (X n - x) : by rewrite [-smul_sub_left_distrib, norm_smul]
... < abs c * (ε / abs c) : mul_lt_mul_of_pos_left H abscpos
... = ε : mul_div_cancel' (ne_of_gt abscpos))
proposition smul_converges_to_seq (c : ℝ) (HX : X ⟶ x in ℕ) :
(λ n, c • X n) ⟶ c • x in ℕ :=
by_cases
(assume cz : c = 0,
have (λ n, c • X n) = (λ n, 0), from funext (take x, by rewrite [cz, zero_smul]),
begin+ rewrite [this, cz, zero_smul], apply converges_to_seq_constant end)
(suppose c ≠ 0, smul_converges_to_seq_aux this HX)
proposition neg_converges_to_seq (HX : X ⟶ x in ℕ) :
(λ n, - X n) ⟶ - x in ℕ :=
take ε, suppose ε > 0,
obtain N (HN : ∀ {n}, n ≥ N → norm (X n - x) < ε), from converges_to_seq_norm_elim HX this,
exists.intro N
(take n,
suppose n ≥ N,
show norm (- X n - (- x)) < ε,
by rewrite [-neg_neg_sub_neg, *neg_neg, norm_neg]; exact HN `n ≥ N`)
proposition neg_converges_to_seq_iff : ((λ n, - X n) ⟶ - x in ℕ) ↔ (X ⟶ x in ℕ) :=
have aux : X = λ n, (- (- X n)), from funext (take n, by rewrite neg_neg),
iff.intro
(assume H : (λ n, -X n)⟶ -x in ℕ,
show X ⟶ x in ℕ, by+ rewrite [aux, -neg_neg x]; exact neg_converges_to_seq H)
neg_converges_to_seq
proposition norm_converges_to_seq_zero (HX : X ⟶ 0 in ℕ) : (λ n, norm (X n)) ⟶ 0 in ℕ :=
take ε, suppose ε > 0,
obtain N (HN : ∀ n, n ≥ N → norm (X n - 0) < ε), from HX `ε > 0`,
exists.intro N
(take n, assume Hn : n ≥ N,
have norm (X n) < ε, begin rewrite -(sub_zero (X n)), apply HN n Hn end,
show abs (norm (X n) - 0) < ε, using this,
by rewrite [sub_zero, abs_of_nonneg !norm_nonneg]; apply this)
proposition converges_to_seq_zero_of_norm_converges_to_seq_zero
(HX : (λ n, norm (X n)) ⟶ 0 in ℕ) :
X ⟶ 0 in ℕ :=
take ε, suppose ε > 0,
obtain N (HN : ∀ n, n ≥ N → abs (norm (X n) - 0) < ε), from HX `ε > 0`,
exists.intro (N : ℕ)
(take n : ℕ, assume Hn : n ≥ N,
have HN' : abs (norm (X n) - 0) < ε, from HN n Hn,
have norm (X n) < ε,
by+ rewrite [sub_zero at HN', abs_of_nonneg !norm_nonneg at HN']; apply HN',
show norm (X n - 0) < ε, using this,
by rewrite sub_zero; apply this)
proposition norm_converges_to_seq_zero_iff (X : ℕ → V) :
((λ n, norm (X n)) ⟶ 0 in ℕ) ↔ (X ⟶ 0 in ℕ) :=
iff.intro converges_to_seq_zero_of_norm_converges_to_seq_zero norm_converges_to_seq_zero
end analysis
|
679dab3b999e82242a264cdf9549f43bbd464023 | e61bd74d1f38315f3bf7c924da3ee8d67d73fdab | /src/syntax.lean | cc672c57289350a4a148dc64333f1ef005693249 | [] | no_license | maxd13/logic-soundness | 4e0ef2ca8be1ed24ae0f1b4b9e50e63c6f231fb7 | 8821cc01ffcd3a73ed1e0eaaf2c97694fb4f422a | refs/heads/master | 1,670,286,287,157 | 1,598,023,967,000 | 1,598,023,967,000 | 263,057,652 | 4 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 19,159 | lean | import data.set.lattice tactic.find tactic.tidy tactic.ring
universe u
-- We implement first order predicate logic.
namespace logic
open list tactic set
-- The type of signatures, which defines a first-order language,
-- possibly with extra modalities, and with room for defining your
-- own preferred variable type.
@[derive inhabited]
structure signature : Type (u+1) :=
(functional_symbol : Type u := pempty)
(relational_symbol : Type u := pempty)
(modality : Type u := pempty)
(vars : Type u := ulift ℕ)
(dec_vars : decidable_eq vars . apply_instance)
(arity : functional_symbol → ℕ := λ_, 0)
(rarity : relational_symbol → ℕ := λ_, 0)
(marity : modality → ℕ := λ_, 0)
-- A pseudo-predicate saying that the we can decide the equality
-- between any symbols of the signature.
-- Many definitions of proof theory need us to decide whether
-- 2 symbols are equal, but many also do not, which justifies us
-- keeping this as a separate structure.
class signature.symbolic (σ : signature) :=
(dec_fun : decidable_eq σ.functional_symbol)
(dec_rel : decidable_eq σ.relational_symbol)
(dec_mod : decidable_eq σ.modality)
-- decidable_eq instances that we get to infer from a
-- (symbolic) signature.
instance dec_vars (σ : signature) : decidable_eq σ.vars := σ.dec_vars
instance dec_fun (σ : signature) [h : σ.symbolic] : decidable_eq σ.functional_symbol := h.dec_fun
instance dec_rel (σ : signature) [h : σ.symbolic] : decidable_eq σ.relational_symbol := h.dec_rel
instance dec_mod (σ : signature) [h : σ.symbolic] : decidable_eq σ.modality := h.dec_mod
-- The signature whose formulas are propositional formulas built up
-- from taking the instances of type α as propositional variables.
def propositional_signature (α : Type u := ulift ℕ) : signature :=
{
relational_symbol := α,
vars := pempty,
dec_vars := by apply_instance,
}
-- here we start with the syntactical definitions
variable {σ : signature}
-- arity types
-- the type of functional symbols of arity n
def signature.nary (σ : signature) (n : ℕ) := subtype {f : σ.functional_symbol | σ.arity f = n}
-- the type of relational symbols of arity n
def signature.nrary (σ : signature) (n : ℕ) := subtype {r : σ.relational_symbol | σ.rarity r = n}
-- the predicate defining, and the type of, constants
def is_constant (f : σ.functional_symbol) := σ.arity f = 0
def signature.const (σ : signature) := σ.nary 0
-- terms in the language
inductive signature.term (σ : signature)
| var : σ.vars → signature.term
| app {n : ℕ} (f : σ.nary n) (v : fin n → signature.term) : signature.term
-- constant terms. A function that lifts a constant to a term.
def signature.cterm (σ : signature) : σ.const → σ.term
| c := term.app c fin_zero_elim
-- Rewrite a variable for a term in a term.
-- This is also called a substitution of a variable for a term.
def signature.term.rw : σ.term → σ.vars → σ.term → σ.term
| (term.var a) x t := if x = a then t else term.var a
| (term.app f v) x t :=
let v₂ := λ m, signature.term.rw (v m) x t in
term.app f v₂
-- Get the set of variables of a term.
def signature.term.vars : σ.term → set σ.vars
| (term.var a) := {a}
| (term.app f v) :=
let v₂ := λ m, signature.term.vars (v m) in
⋃ m, v₂ m
-- denotative and non-denotative terms.
@[reducible]
def signature.term.denotes (t : σ.term) : Prop := t.vars = (∅ : set σ.vars)
@[reducible]
def signature.term.conotes (t : σ.term) := ¬ t.denotes
-- a closed term is a Herbrand term.
def signature.hterm (σ : signature) := subtype {t : σ.term | t.denotes}
-- an open term is an expression.
def signature.expression (σ : signature) := subtype {t : σ.term | t.conotes}
-- some lemmas about term rewriting:
theorem rw_eq_of_not_in_vars : ∀ (t₁ t₂ : σ.term) (x : σ.vars), x ∉ t₁.vars → t₁.rw x t₂ = t₁ :=
begin
intros t₁ t₂ x,
induction t₁;
dunfold signature.term.vars signature.term.rw;
simp;
intro h,
simp[h],
ext y,
specialize h y,
exact t₁_ih y h,
end
theorem trivial_rw : ∀ (t: σ.term) (x), t.rw x (term.var x) = t :=
begin
intros t x,
induction t;
dunfold signature.term.rw,
by_cases x = t;
simp [h],
simp at *,
ext y,
exact t_ih y,
end
theorem den_rw : ∀ (t₁ t₂ : σ.term) (x : σ.vars), t₁.denotes → t₁.rw x t₂ = t₁ :=
begin
intros t₁ t₂ x den₁,
induction t₁,
-- case var
replace den₁ : (term.var t₁).vars = ∅ := den₁,
replace den₁ : {t₁} = ∅ := den₁,
replace den₁ := eq_empty_iff_forall_not_mem.mp den₁,
specialize den₁ t₁,
simp at den₁,
contradiction,
-- case app
replace den₁ : (term.app t₁_f t₁_v).vars = ∅ := den₁,
let v₂ := λ m, (t₁_v m).vars,
replace den₁ : (⋃ m, v₂ m) = ∅ := den₁,
have c₀ : ∀ m, (v₂ m) = ∅,
intro m,
ext, constructor, intro h,
simp,
have c : x_1 ∈ (⋃ m, v₂ m),
simp,
existsi m,
exact h,
rwa den₁ at c,
intro insanity,
simp at insanity,
contradiction,
have c₁ : ∀ m, (t₁_v m).denotes := c₀,
have c₂ : ∀ m, (t₁_v m).rw x t₂ = (t₁_v m),
intro m,
exact t₁_ih m (c₁ m),
dunfold signature.term.rw,
simp[c₂],
end
-- Some auxiliary functions about terms (mostly unused):
-- subterms of a term.
def signature.term.subterms : σ.term → set σ.term
| (term.app f v) :=
let v₂ := λ m, signature.term.subterms (v m) in
(⋃ m, v₂ m) ∪ {(term.app f v)}
| t := {t}
-- set of all variables appearing in a list of terms.
def list.vars : list σ.term → set σ.vars
| [] := ∅
| (hd :: tl) := hd.vars ∪ tl.vars
-- subterms of a list of terms.
def list.subterms : list σ.term → set σ.term
| [] := ∅
| (hd :: tl) := hd.subterms ∪ tl.subterms
-- the same for sets.
def subterms : set σ.term → set σ.term
| S := ⋃ x ∈ S, signature.term.subterms x
-- rewrite a variable in a list of terms.
def list.rw : list σ.term → σ.vars → σ.term → list σ.term
| [] _ _:= ∅
| (hd :: tl) x t := (hd.rw x t) :: tl.rw x t
-- the type of formulas in the language
inductive signature.formula (σ : signature)
| relational {n : ℕ} (r : σ.nrary n) (v : fin n → σ.term) : signature.formula
| for_all : σ.vars → signature.formula → signature.formula
| if_then : signature.formula → signature.formula → signature.formula
| equation (t₁ t₂ : σ.term) : signature.formula
| false : signature.formula
-- a convenient notation to set up for if_then
reserve infixr ` ⇒ `:55
class has_exp (α : Type u) := (exp : α → α → α)
infixr ⇒ := has_exp.exp
instance signature.formula.has_exp : has_exp σ.formula := ⟨signature.formula.if_then⟩
-- definition of connectives
def signature.formula.not (φ : σ.formula) := φ ⇒ signature.formula.false
def signature.formula.or (φ ψ : σ.formula) := φ.not ⇒ ψ
def signature.formula.and (φ ψ : σ.formula) := (φ.not.or ψ.not).not
def signature.formula.iff (φ ψ : σ.formula) := (φ ⇒ ψ).and (ψ ⇒ φ)
def signature.formula.exists (φ : σ.formula) (x : σ.vars) := (signature.formula.for_all x φ.not).not
-- Rewrite (substitute) a variable for a term in a formula.
def signature.formula.rw : σ.formula → σ.vars → σ.term → σ.formula
| ( signature.formula.relational r v) x t :=
let v₂ := λ m, (v m).rw x t in
signature.formula.relational r v₂
| ( signature.formula.for_all y φ) x t :=
let ψ := if y = x then φ else φ.rw x t in
signature.formula.for_all y ψ
| ( signature.formula.if_then φ ψ) x t := (φ.rw x t) ⇒ (ψ.rw x t)
| ( signature.formula.equation t₁ t₂) x t := signature.formula.equation (t₁.rw x t) (t₂.rw x t)
| φ _ _ := φ
-- free variables
def signature.formula.free : σ.formula → set σ.vars
| ( signature.formula.relational r v) := ⋃ m, (v m).vars
| ( signature.formula.for_all x φ) := φ.free - {x}
| ( signature.formula.if_then φ ψ) := φ.free ∪ ψ.free
| ( signature.formula.equation t₁ t₂) := t₁.vars ∪ t₂.vars
| signature.formula.false := ∅
-- definition of whether a variable is
-- substitutable for a term in a formula.
-- Needed for proving some lemmas.
def signature.formula.substitutable : σ.formula → σ.vars → σ.term → Prop
| ( signature.formula.for_all y φ) x t := x ∉ ( signature.formula.for_all y φ).free ∨
(y ∉ t.vars ∧ φ.substitutable x t)
| ( signature.formula.if_then φ ψ) y t := φ.substitutable y t ∧ ψ.substitutable y t
| _ _ _ := true
-- open and closed σ.formulas.
def signature.formula.closed : σ.formula → Prop
| φ := φ.free = ∅
def signature.formula.open : σ.formula → Prop
| φ := ¬ φ.closed
-- atomic and molecular formulas
def signature.formula.atomic : σ.formula → bool
| (formula.relational r v) := tt
| (formula.equation t₁ t₂) := tt
| formula.false := tt
| _ := ff
def signature.formula.molecular : σ.formula → bool
| (formula.for_all x φ) := ff
| (formula.if_then φ ψ) := φ.molecular && ψ.molecular
| _ := tt
-- utility for propositional logic
def signature.proposition (σ : signature) := subtype {φ : σ.formula | φ.molecular}
-- variables present in a formula
def signature.formula.vars : σ.formula → set σ.vars
| ( signature.formula.for_all x φ) := φ.free ∪ {x}
| ( signature.formula.if_then φ ψ) := φ.vars ∪ ψ.vars
| φ := φ.free
-- terms present in a formula
def signature.formula.terms : σ.formula → set σ.term
| ( signature.formula.relational r v) := list.subterms (of_fn v)
| ( signature.formula.for_all x φ) := φ.terms ∪ {term.var x}
| ( signature.formula.if_then φ ψ) := φ.terms ∪ ψ.terms
| _ := ∅
-- tells wether a term is present in a set of formulas.
-- The name comes from the universal introduction rule,
-- where we prove that a formula is valid for an "abstract"
-- representative and conclude it is universally valid.
def term.abstract_in : σ.term → set σ.formula → Prop
| t S := t ∉ (⋃ φ ∈ S, signature.formula.terms φ)
-- the same for variables.
def abstract_in : σ.vars → set σ.formula → Prop
| x S := x ∉ (⋃ φ ∈ S, signature.formula.free φ)
-- construct the generalization of a σ.formula from a list of variables.
-- This is just a fold but, I like being explicit about my folds when possible.
-- Anyway, this ended up not being used so far.
def signature.formula.generalize : σ.formula → list σ.vars → σ.formula
| φ [] := φ
| φ (x::xs) := signature.formula.for_all x $ φ.generalize xs
-- lemmas about rewriting in formulas:
theorem formula_rw : ∀ {φ : σ.formula} {x : σ.vars}, x ∉ φ.free → ∀(t : σ.term),φ.rw x t = φ :=
begin
intros φ x h t,
revert h,
induction φ;
dunfold signature.formula.free signature.formula.rw;
simp;
intro h,
ext y,
specialize h y,
revert h,
induction φ_v y;
dunfold signature.term.rw signature.term.vars;
intro h;
simp at *,
simp[h],
ext z,
specialize h z,
specialize ih z,
exact ih h,
classical,
by_cases eq₁ : x ∈ φ_a_1.free,
simp [h eq₁],
by_cases eq₂ : φ_a = x;
simp [eq₂],
exact φ_ih eq₁,
all_goals{
push_neg at h,
obtain ⟨h₁, h₂⟩ := h,
},
replace h₁ := φ_ih_a h₁,
replace h₂ := φ_ih_a_1 h₂,
rw [h₁, h₂],
refl,
constructor;
apply rw_eq_of_not_in_vars;
assumption,
end
lemma trivial_formula_rw : ∀ {φ: σ.formula} {x}, φ.rw x (term.var x) = φ :=
begin
intros φ x,
induction φ;
dunfold signature.formula.rw;
try{simp},
ext,
induction (φ_v x_1);
dunfold signature.term.rw,
by_cases x = a;
simp [h],
simp,
ext,
exact ih x_2,
rw φ_ih,
simp,
simp [φ_ih_a, φ_ih_a_1],
refl,
constructor;
apply trivial_rw;
assumption,
end
-- deductive consequence of formulas: Γ ⊢ φ.
-- Type of proofs from Γ to φ.
-- The universe var here has been automatically generated,
inductive proof : set σ.formula → σ.formula → Type u_1
| reflexivity (Γ : set σ.formula) (φ : σ.formula)(h : φ ∈ Γ) : proof Γ φ
| transitivity (Γ Δ : set σ.formula) (φ : σ.formula)
(h₁ : ∀ ψ ∈ Δ, proof Γ ψ)
(h₂ : proof Δ φ) : proof Γ φ
| modus_ponens
(φ ψ : σ.formula) (Γ : set σ.formula)
(h₁ : proof Γ (φ ⇒ ψ))
(h₂ : proof Γ φ)
: proof Γ ψ
| intro
(φ ψ : σ.formula) (Γ : set σ.formula)
(h : proof (Γ ∪ {φ}) ψ)
: proof Γ (φ ⇒ ψ)
| for_all_intro
(Γ : set σ.formula) (φ : σ.formula)
(x : σ.vars) (xf : x ∈ φ.free)
(abs : abstract_in x Γ)
(h : proof Γ φ)
: proof Γ ( signature.formula.for_all x φ)
| for_all_elim
(Γ : set σ.formula) (φ : σ.formula)
(x : σ.vars) --(xf : x ∈ φ.free)
(t : σ.term) (sub : φ.substitutable x t)
(h : proof Γ ( signature.formula.for_all x φ))
: proof Γ (φ.rw x t)
| exfalso (Γ : set σ.formula) (φ : σ.formula)
(h : proof Γ signature.formula.false)
: proof Γ φ
| by_contradiction (Γ : set σ.formula) (φ : σ.formula)
(h : proof Γ φ.not.not)
: proof Γ φ
| identity_intro
(Γ : set σ.formula) (t : σ.term)
: proof Γ ( signature.formula.equation t t)
| identity_elim
(Γ : set σ.formula) (φ : σ.formula)
(x : σ.vars) (xf : x ∈ φ.free)
(t₁ t₂: σ.term)
(sub₁ : φ.substitutable x t₁)
(sub₂ : φ.substitutable x t₂)
(h : proof Γ (φ.rw x t₁))
(eq : proof Γ ( signature.formula.equation t₁ t₂))
: proof Γ (φ.rw x t₂)
local infixr `⊢`:55 := proof
-- Some simple (meta-)theorems:
variables (Γ Δ : set σ.formula) (φ : σ.formula)
theorem self_entailment : Γ ⊢ (φ ⇒ φ) :=
begin
apply proof.intro,
apply proof.reflexivity (Γ∪{φ}) φ,
simp
end
theorem monotonicity : Δ ⊆ Γ → Δ ⊢ φ → Γ ⊢ φ :=
begin
intros H h,
have c₁ : ∀ ψ ∈ Δ, proof Γ ψ,
intros ψ hψ,
apply proof.reflexivity Γ ψ,
exact H hψ,
apply proof.transitivity;
assumption,
end
-- The following commented code chunks are unfinished attempts
-- to prove that proofs are finite (they can be safely ignored):
-- This one depends on syntatical equality between σ.formulas
-- being decidable, which in turn depends on the equality of
-- functional and relational symbols being decidable
-- (i.e. σ must be "symbolic"). We will probably move this
-- to another module to deal with "symbolic" signatures later.
-- extracts the premisses (∈ Γ) use to prove φ from Γ.
-- def proof.premisses : Γ ⊢ φ → list (subtype Γ) :=
-- begin
-- intros h,
-- induction h,
-- -- case reflexivity
-- exact [⟨h_φ, h_h⟩],
-- -- case transitivity
-- rename h_ih_h₁ ih₁,
-- induction h_ih_h₂,
-- exact [],
-- obtain ⟨ψ, H⟩ := h_ih_h₂_hd,
-- specialize ih₁ ψ H,
-- exact ih₁ ++ h_ih_h₂_ih,
-- -- case modus ponens
-- exact h_ih_h₁ ++ h_ih_h₂,
-- -- case intro
-- set t : set σ.formula := h_Γ ∪ {h_φ},
-- have ct : h_φ ∈ t, simp,
-- let c : subtype t := ⟨h_φ, ct⟩,
-- all_goals{admit},
-- end
-- This here are earlier attempts to squash proof trees either as lists
-- or finsets.
-- open finset
-- local notation `{` x `}ₙ` := finset.singleton x
-- #find ∀ _ ∈ _, ∃ _, _
-- def list.to_set : list σ.formula → set σ.formula
-- | [] := ∅
-- | (φ::xs) := {φ} ∪ xs.to_set
-- def proof : list σ.formula → Prop
-- | [] := false
-- | (ψ::[]) := ψ ∈ Γ ∨ ∅ ⊢ ψ
-- | (ψ::xs) := (ψ ∈ Γ ∨ list.to_set xs ⊢ ψ) ∧
-- proof xs
-- def proof_of (φ) : list σ.formula → Prop
-- | [] := false
-- | (ψ::xs) := ψ = φ ∧ proof Γ (ψ::xs)
-- theorem finite_proofs : Γ ⊢ φ → ∃ xs : list σ.formula, proof_of Γ φ xs :=
-- begin
-- intro h,
-- induction h,
-- -- case reflexivity
-- let xs := [h_φ],
-- use xs,
-- simp [xs, proof_of,proof],
-- left,
-- assumption,
-- -- case transitivity
-- rename h_ih_h₁ ih,
-- obtain ⟨p, hp⟩ := h_ih_h₂,
-- -- let xs : list σ.formula,
-- -- cases p;
-- -- simp[proof_of] at hp,
-- -- contradiction,
-- -- obtain ⟨hp₁, hp₂⟩ := hp,
-- -- revert hp₂,
-- admit,
-- -- case modus ponens
-- end
-- theorem finite_proofs : Γ ⊢ φ → ∃ Δ : finset σ.formula, ↑Δ ⊆ Γ ∧ ↑Δ ⊢ φ :=
-- begin
-- intro h,
-- induction h,
-- -- case reflexivity
-- existsi finset.singleton h_φ,
-- simp [proof.reflexivity],
-- assumption,
-- -- case transitivity
-- obtain ⟨Δ, HΔ, hΔ⟩ := h_ih_h₂,
-- -- have c : ∀ ψ ∈ Δ, ∃ (Δ₂ : finset σ.formula), ↑Δ₂ ⊆ h_Γ ∧ proof ↑Δ₂ ψ,
-- -- intros ψ Hψ,
-- -- exact h_ih_h₁ ψ (HΔ Hψ),
-- -- have c := λ ψ ∈ Δ, classical.subtype_of_exists (h_ih_h₁ ψ (HΔ _)),
-- -- have c₂ : ⋃ ψ ∈ Δ, classical.some (h_ih_h₁ ψ (HΔ _)),
-- -- have d : ∀ {α}
-- -- induction Δ using finset.induction,
-- -- admit,
-- -- use ∅,
-- -- simp,
-- -- exact hΔ,
-- -- classical,
-- -- by_cases ne : Δ.nonempty,
-- -- obtain ⟨ψ, Hψ⟩ := ne,
-- -- have ih := h_ih_h₁ ψ H,
-- -- existsi ⋃ ψ ∈ Δ, (c ψ H).val,
-- end
-- Consistency doesn't need to be defined just for theories.
def consistent (Γ : set σ.formula) := ¬ nonempty (Γ ⊢ signature.formula.false)
-- At any rate we can define it for theories as well.
-- Here is the definition of a theory:
def signature.theory (σ : signature) := subtype {Γ : set σ.formula | ∀ φ, Γ ⊢ φ → φ ∈ Γ}
def theory.consistent (Γ : σ.theory) := consistent Γ.val
end logic |
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