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c85f8e8fcb1048be395a2376d273aff047725b34 | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/data/multiset/nodup.lean | afd1d1a6cb89eb1e8f2a9f34532f95e1cfaea7ee | [
"Apache-2.0"
] | permissive | jjgarzella/mathlib | 96a345378c4e0bf26cf604aed84f90329e4896a2 | 395d8716c3ad03747059d482090e2bb97db612c8 | refs/heads/master | 1,686,480,124,379 | 1,625,163,323,000 | 1,625,163,323,000 | 281,190,421 | 2 | 0 | Apache-2.0 | 1,595,268,170,000 | 1,595,268,169,000 | null | UTF-8 | Lean | false | false | 9,966 | 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.powerset
import data.multiset.range
/-!
# The `nodup` predicate for multisets without duplicate elements.
-/
namespace multiset
open list
variables {α β γ : Type*}
/- 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
theorem nodup_cons_of_nodup {a : α} {s : multiset α} (m : a ∉ s) (n : nodup s) : nodup (a ::ₘ s) :=
nodup_cons.2 ⟨m, n⟩
theorem nodup_singleton : ∀ a : α, nodup (a ::ₘ 0) := nodup_singleton
theorem nodup_of_nodup_cons {a : α} {s : multiset α} (h : nodup (a ::ₘ s)) : nodup s :=
(nodup_cons.1 h).2
theorem not_mem_of_nodup_cons {a : α} {s : multiset α} (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_of_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 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
lemma pairwise_of_nodup {r : α → α → Prop} {s : multiset α} :
(∀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 forall_of_pairwise {r : α → α → Prop} (H : symmetric r) {s : multiset α}
(hs : pairwise r s) : (∀a∈s, ∀b∈s, a ≠ b → r a b) :=
let ⟨l, hl₁, hl₂⟩ := hs in hl₁.symm ▸ list.forall_of_pairwise H hl₂
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
theorem nodup_add_of_nodup {s t : multiset α} (d₁ : nodup s) (d₂ : nodup t) :
nodup (s + t) ↔ disjoint s t :=
by simp [nodup_add, d₁, d₂]
theorem nodup_of_nodup_map (f : α → β) {s : multiset α} : nodup (map f s) → nodup s :=
quot.induction_on s $ λ l, nodup_of_nodup_map f
theorem nodup_map_on {f : α → β} {s : multiset α} : (∀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
theorem nodup_map {f : α → β} {s : multiset α} (hf : function.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, nodup_map_on h d⟩
theorem 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
theorem 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
theorem 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 $ nodup_erase_eq_filter a d
theorem nodup_erase_of_nodup [decidable_eq α] (a : α) {l} : nodup l → nodup (l.erase a) :=
nodup_of_le (erase_le _ _)
theorem mem_erase_iff_of_nodup [decidable_eq α] {a b : α} {l} (d : nodup l) :
a ∈ l.erase b ↔ a ≠ b ∧ a ∈ l :=
by rw nodup_erase_eq_filter b d; simp [and_comm]
theorem mem_erase_of_nodup [decidable_eq α] {a : α} {l} (h : nodup l) : a ∉ l.erase a :=
by rw mem_erase_iff_of_nodup h; simp
theorem nodup_product {s : multiset α} {t : multiset β} : nodup s → nodup t → nodup (product s t) :=
quotient.induction_on₂ s t $ λ l₁ l₂ d₁ d₂, by simp [nodup_product d₁ d₂]
theorem nodup_sigma {σ : α → Type*} {s : multiset α} {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
theorem nodup_filter_map (f : α → option β) {s : multiset α}
(H : ∀ (a a' : α) (b : β), 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 _
theorem nodup_inter_left [decidable_eq α] {s : multiset α} (t) : nodup s → nodup (s ∩ t) :=
nodup_of_le $ inter_le_left _ _
theorem nodup_inter_right [decidable_eq α] (s) {t : multiset α} : 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_nodup_map _ (nodup_of_le (map_single_le_powerset _) h),
quotient.induction_on s $ λ l h,
by simp; refine list.nodup_map_on _ (nodup_sublists'.2 h); exact
λ x sx y sy e,
(h.sublist_ext (mem_sublists'.1 sx) (mem_sublists'.1 sy)).1
(quotient.exact e)⟩
theorem nodup_powerset_len {n : ℕ} {s : multiset α}
(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]
theorem 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, subperm_of_subset_nodup d⟩
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 (sub_le_self _ _) h, λ h',
by refine count_eq_zero.1 _ h; rw [count_sub a s t, nat.sub_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_sub_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 (nodup_ext ht (nodup_map
(show function.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))
(nodup_attach.2 hs))).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 (λ x _, h _ _)
end multiset
|
fdbd2f0ed9497a00e1460f65bb41eb9f551ae2c3 | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/group_theory/solvable.lean | e9ae039668dda46ce555784ca1b8e3511454b5ba | [
"Apache-2.0"
] | permissive | alreadydone/mathlib | dc0be621c6c8208c581f5170a8216c5ba6721927 | c982179ec21091d3e102d8a5d9f5fe06c8fafb73 | refs/heads/master | 1,685,523,275,196 | 1,670,184,141,000 | 1,670,184,141,000 | 287,574,545 | 0 | 0 | Apache-2.0 | 1,670,290,714,000 | 1,597,421,623,000 | Lean | UTF-8 | Lean | false | false | 7,610 | lean | /-
Copyright (c) 2021 Jordan Brown, Thomas Browning, Patrick Lutz. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jordan Brown, Thomas Browning, Patrick Lutz
-/
import data.fin.vec_notation
import group_theory.abelianization
import group_theory.perm.via_embedding
import set_theory.cardinal.basic
/-!
# Solvable Groups
In this file we introduce the notion of a solvable group. We define a solvable group as one whose
derived series is eventually trivial. This requires defining the commutator of two subgroups and
the derived series of a group.
## Main definitions
* `derived_series G n` : the `n`th term in the derived series of `G`, defined by iterating
`general_commutator` starting with the top subgroup
* `is_solvable G` : the group `G` is solvable
-/
open subgroup
variables {G G' : Type*} [group G] [group G'] {f : G →* G'}
section derived_series
variables (G)
/-- The derived series of the group `G`, obtained by starting from the subgroup `⊤` and repeatedly
taking the commutator of the previous subgroup with itself for `n` times. -/
def derived_series : ℕ → subgroup G
| 0 := ⊤
| (n + 1) := ⁅(derived_series n), (derived_series n)⁆
@[simp] lemma derived_series_zero : derived_series G 0 = ⊤ := rfl
@[simp] lemma derived_series_succ (n : ℕ) :
derived_series G (n + 1) = ⁅(derived_series G n), (derived_series G n)⁆ := rfl
lemma derived_series_normal (n : ℕ) : (derived_series G n).normal :=
begin
induction n with n ih,
{ exact (⊤ : subgroup G).normal_of_characteristic },
{ exactI subgroup.commutator_normal (derived_series G n) (derived_series G n) }
end
@[simp] lemma derived_series_one : derived_series G 1 = commutator G :=
rfl
end derived_series
section commutator_map
section derived_series_map
variables (f)
lemma map_derived_series_le_derived_series (n : ℕ) :
(derived_series G n).map f ≤ derived_series G' n :=
begin
induction n with n ih,
{ exact le_top },
{ simp only [derived_series_succ, map_commutator, commutator_mono, ih] }
end
variables {f}
lemma derived_series_le_map_derived_series (hf : function.surjective f) (n : ℕ) :
derived_series G' n ≤ (derived_series G n).map f :=
begin
induction n with n ih,
{ exact (map_top_of_surjective f hf).ge },
{ exact commutator_le_map_commutator ih ih }
end
lemma map_derived_series_eq (hf : function.surjective f) (n : ℕ) :
(derived_series G n).map f = derived_series G' n :=
le_antisymm (map_derived_series_le_derived_series f n) (derived_series_le_map_derived_series hf n)
end derived_series_map
end commutator_map
section solvable
variables (G)
/-- A group `G` is solvable if its derived series is eventually trivial. We use this definition
because it's the most convenient one to work with. -/
class is_solvable : Prop :=
(solvable : ∃ n : ℕ, derived_series G n = ⊥)
lemma is_solvable_def : is_solvable G ↔ ∃ n : ℕ, derived_series G n = ⊥ :=
⟨λ h, h.solvable, λ h, ⟨h⟩⟩
@[priority 100]
instance comm_group.is_solvable {G : Type*} [comm_group G] : is_solvable G :=
⟨⟨1, le_bot_iff.mp (abelianization.commutator_subset_ker (monoid_hom.id G))⟩⟩
lemma is_solvable_of_comm {G : Type*} [hG : group G]
(h : ∀ a b : G, a * b = b * a) : is_solvable G :=
begin
letI hG' : comm_group G := { mul_comm := h .. hG },
casesI hG,
exact comm_group.is_solvable,
end
lemma is_solvable_of_top_eq_bot (h : (⊤ : subgroup G) = ⊥) : is_solvable G :=
⟨⟨0, h⟩⟩
@[priority 100]
instance is_solvable_of_subsingleton [subsingleton G] : is_solvable G :=
is_solvable_of_top_eq_bot G (by ext; simp at *)
variables {G}
lemma solvable_of_ker_le_range {G' G'' : Type*} [group G'] [group G''] (f : G' →* G)
(g : G →* G'') (hfg : g.ker ≤ f.range) [hG' : is_solvable G'] [hG'' : is_solvable G''] :
is_solvable G :=
begin
obtain ⟨n, hn⟩ := id hG'',
obtain ⟨m, hm⟩ := id hG',
refine ⟨⟨n + m, le_bot_iff.mp (map_bot f ▸ (hm ▸ _))⟩⟩,
clear hm,
induction m with m hm,
{ exact f.range_eq_map ▸ ((derived_series G n).map_eq_bot_iff.mp (le_bot_iff.mp
((map_derived_series_le_derived_series g n).trans hn.le))).trans hfg },
{ exact commutator_le_map_commutator hm hm },
end
lemma solvable_of_solvable_injective (hf : function.injective f) [h : is_solvable G'] :
is_solvable G :=
solvable_of_ker_le_range (1 : G' →* G) f ((f.ker_eq_bot_iff.mpr hf).symm ▸ bot_le)
instance subgroup_solvable_of_solvable (H : subgroup G) [h : is_solvable G] : is_solvable H :=
solvable_of_solvable_injective H.subtype_injective
lemma solvable_of_surjective (hf : function.surjective f) [h : is_solvable G] :
is_solvable G' :=
solvable_of_ker_le_range f (1 : G' →* G) ((f.range_top_of_surjective hf).symm ▸ le_top)
instance solvable_quotient_of_solvable (H : subgroup G) [H.normal] [h : is_solvable G] :
is_solvable (G ⧸ H) :=
solvable_of_surjective (quotient_group.mk'_surjective H)
instance solvable_prod {G' : Type*} [group G'] [h : is_solvable G] [h' : is_solvable G'] :
is_solvable (G × G') :=
solvable_of_ker_le_range (monoid_hom.inl G G') (monoid_hom.snd G G')
(λ x hx, ⟨x.1, prod.ext rfl hx.symm⟩)
end solvable
section is_simple_group
variable [is_simple_group G]
lemma is_simple_group.derived_series_succ {n : ℕ} : derived_series G n.succ = commutator G :=
begin
induction n with n ih,
{ exact derived_series_one G },
rw [derived_series_succ, ih],
cases (commutator.normal G).eq_bot_or_eq_top with h h,
{ rw [h, commutator_bot_left] },
{ rwa h },
end
lemma is_simple_group.comm_iff_is_solvable :
(∀ a b : G, a * b = b * a) ↔ is_solvable G :=
⟨is_solvable_of_comm, λ ⟨⟨n, hn⟩⟩, begin
cases n,
{ intros a b,
refine (mem_bot.1 _).trans (mem_bot.1 _).symm;
{ rw ← hn,
exact mem_top _ } },
{ rw is_simple_group.derived_series_succ at hn,
intros a b,
rw [← mul_inv_eq_one, mul_inv_rev, ← mul_assoc, ← mem_bot, ← hn, commutator_eq_closure],
exact subset_closure ⟨a, b, rfl⟩ }
end⟩
end is_simple_group
section perm_not_solvable
lemma not_solvable_of_mem_derived_series {g : G} (h1 : g ≠ 1)
(h2 : ∀ n : ℕ, g ∈ derived_series G n) : ¬ is_solvable G :=
mt (is_solvable_def _).mp (not_exists_of_forall_not
(λ n h, h1 (subgroup.mem_bot.mp ((congr_arg (has_mem.mem g) h).mp (h2 n)))))
lemma equiv.perm.fin_5_not_solvable : ¬ is_solvable (equiv.perm (fin 5)) :=
begin
let x : equiv.perm (fin 5) := ⟨![1, 2, 0, 3, 4], ![2, 0, 1, 3, 4], dec_trivial, dec_trivial⟩,
let y : equiv.perm (fin 5) := ⟨![3, 4, 2, 0, 1], ![3, 4, 2, 0, 1], dec_trivial, dec_trivial⟩,
let z : equiv.perm (fin 5) := ⟨![0, 3, 2, 1, 4], ![0, 3, 2, 1, 4], dec_trivial, dec_trivial⟩,
have key : x = z * ⁅x, y * x * y⁻¹⁆ * z⁻¹ := by dec_trivial,
refine not_solvable_of_mem_derived_series (show x ≠ 1, by dec_trivial) (λ n, _),
induction n with n ih,
{ exact mem_top x },
{ rw [key, (derived_series_normal _ _).mem_comm_iff, inv_mul_cancel_left],
exact commutator_mem_commutator ih ((derived_series_normal _ _).conj_mem _ ih _) },
end
lemma equiv.perm.not_solvable (X : Type*) (hX : 5 ≤ cardinal.mk X) :
¬ is_solvable (equiv.perm X) :=
begin
introI h,
have key : nonempty (fin 5 ↪ X),
{ rwa [←cardinal.lift_mk_le, cardinal.mk_fin, cardinal.lift_nat_cast,
nat.cast_bit1, nat.cast_bit0, nat.cast_one, cardinal.lift_id] },
exact equiv.perm.fin_5_not_solvable (solvable_of_solvable_injective
(equiv.perm.via_embedding_hom_injective (nonempty.some key))),
end
end perm_not_solvable
|
072c508904839d42c418e5b216105dbd55f11760 | a4673261e60b025e2c8c825dfa4ab9108246c32e | /stage0/src/Lean/Compiler/InitAttr.lean | 5f1b5dd8d195fc4f288508b9a0a8c720d37d0620 | [
"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 | 4,373 | 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.Environment
import Lean.Attributes
namespace Lean
private def getIOTypeArg : Expr → Option Expr
| Expr.app (Expr.const `IO _ _) arg _ => some arg
| _ => none
private def isUnitType : Expr → Bool
| Expr.const `Unit _ _ => true
| _ => false
private def isIOUnit (type : Expr) : Bool :=
match getIOTypeArg type with
| some type => isUnitType type
| _ => false
/-- Run the initializer for `decl` and store its value for global access. Should only be used while importing. -/
@[extern "lean_run_init"]
unsafe constant runInit (env : @& Environment) (opts : @& Options) (decl initDecl : @& Name) : IO Unit
unsafe def registerInitAttrUnsafe (attrName : Name) (runAfterImport : Bool) : IO (ParametricAttribute Name) :=
registerParametricAttribute {
name := attrName,
descr := "initialization procedure for global references",
getParam := fun declName stx => do
let decl ← getConstInfo declName
match attrParamSyntaxToIdentifier stx with
| some initFnName =>
let initFnName ← resolveGlobalConstNoOverload initFnName
let initDecl ← getConstInfo initFnName
match getIOTypeArg initDecl.type with
| none => throwError ("initialization function '" ++ initFnName ++ "' must have type of the form `IO <type>`")
| some initTypeArg =>
if decl.type == initTypeArg then pure initFnName
else throwError ("initialization function '" ++ initFnName ++ "' type mismatch")
| _ => match stx with
| Syntax.missing =>
if isIOUnit decl.type then pure Name.anonymous
else throwError "initialization function must have type `IO Unit`"
| _ => throwError "unexpected kind of argument",
afterImport := fun entries => do
let ctx ← read
when runAfterImport do
for modEntries in entries do
for (decl, initDecl) in modEntries do
if initDecl.isAnonymous then
_ ← IO.ofExcept $ ctx.env.evalConst (IO Unit) ctx.opts decl
else runInit ctx.env ctx.opts decl initDecl
}
@[implementedBy registerInitAttrUnsafe]
constant registerInitAttr (attrName : Name) (runAfterImport : Bool) : IO (ParametricAttribute Name)
builtin_initialize regularInitAttr : ParametricAttribute Name ← registerInitAttr `init true
builtin_initialize builtinInitAttr : ParametricAttribute Name ← registerInitAttr `builtinInit false
def getInitFnNameForCore? (env : Environment) (attr : ParametricAttribute Name) (fn : Name) : Option Name :=
match attr.getParam env fn with
| some Name.anonymous => none
| some n => some n
| _ => none
@[export lean_get_builtin_init_fn_name_for]
def getBuiltinInitFnNameFor? (env : Environment) (fn : Name) : Option Name :=
getInitFnNameForCore? env builtinInitAttr fn
@[export lean_get_regular_init_fn_name_for]
def getRegularInitFnNameFor? (env : Environment) (fn : Name) : Option Name :=
getInitFnNameForCore? env regularInitAttr fn
@[export lean_get_init_fn_name_for]
def getInitFnNameFor? (env : Environment) (fn : Name) : Option Name :=
getBuiltinInitFnNameFor? env fn <|> getRegularInitFnNameFor? env fn
def isIOUnitInitFnCore (env : Environment) (attr : ParametricAttribute Name) (fn : Name) : Bool :=
match attr.getParam env fn with
| some Name.anonymous => true
| _ => false
@[export lean_is_io_unit_regular_init_fn]
def isIOUnitRegularInitFn (env : Environment) (fn : Name) : Bool :=
isIOUnitInitFnCore env regularInitAttr fn
@[export lean_is_io_unit_builtin_init_fn]
def isIOUnitBuiltinInitFn (env : Environment) (fn : Name) : Bool :=
isIOUnitInitFnCore env builtinInitAttr fn
def isIOUnitInitFn (env : Environment) (fn : Name) : Bool :=
isIOUnitBuiltinInitFn env fn || isIOUnitRegularInitFn env fn
def hasInitAttr (env : Environment) (fn : Name) : Bool :=
(getInitFnNameFor? env fn).isSome
def setBuiltinInitAttr (env : Environment) (declName : Name) (initFnName : Name := Name.anonymous) : Except String Environment :=
-- builtinInitAttr.setParam env declName initFnName -- TODO: use this one
regularInitAttr.setParam env declName initFnName
end Lean
|
80f7b187db90d4a49a62eeb961ddd1b99cd1d428 | 9ad8d18fbe5f120c22b5e035bc240f711d2cbd7e | /src/data/vector_extra.lean | a16df14f4aa7c43d44d996c27407b399745f3053 | [] | no_license | agusakov/lean_lib | c0e9cc29fc7d2518004e224376adeb5e69b5cc1a | f88d162da2f990b87c4d34f5f46bbca2bbc5948e | refs/heads/master | 1,642,141,461,087 | 1,557,395,798,000 | 1,557,395,798,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 3,808 | lean | import data.vector logic.embedding data.fin data.list.basic
import data.list_extra
namespace vector
open vector
variables {α : Type*} {β : Type*} {n m : ℕ}
lemma head_eq_zeroth : ∀ (v : vector α (n + 1)), v.head = nth v 0
| ⟨list.nil,l_len⟩ := by {cases l_len}
| ⟨_ :: _,_⟩ := rfl
def single (a : α) : vector α 1 := a :: vector.nil
lemma head_single (a : α) : (single a).head = a := rfl
lemma single_val (a : α) : (single a).val = [a] := rfl
lemma single_head : ∀ v : vector α 1, v = single v.head
| ⟨list.nil,l_len⟩ := by {cases l_len}
| ⟨[_],l_len⟩ := rfl
| ⟨_ :: _ :: _,l_len⟩ := by {cases l_len}
lemma veq_of_eq {x₀ x₁ : vector α n} (e : x₀ = x₁) :
x₀.val = x₁.val := congr_arg subtype.val e
def concat (v : vector α n) (a : α) : vector α (n + 1) :=
v.append (a :: vector.nil)
def trim : ∀ (v : vector α (n + 1)), vector α n
| ⟨l,l_len⟩ := ⟨l.take n,
by { rw[list.length_take,l_len],
exact min_eq_left (le_of_lt n.lt_succ_self)}⟩
def last (v : vector α (n + 1)) : α := v.nth ⟨n,n.lt_succ_self⟩
lemma trim_to_list : ∀ (v : vector α (n + 1)), v.trim.to_list = v.to_list.take n
| ⟨l,l_len⟩ := rfl
lemma trim_concat : ∀ (v : vector α n) (a : α), (v.concat a).trim = v
| ⟨l,l_len⟩ a := subtype.eq $ by {
change (l ++ [a]).take n = l,
rw[← l_len,list.take_append_of_le_length (le_refl l.length),list.take_all],}
lemma last_concat : ∀ (v : vector α n) (a : α), (v.concat a).last = a
| ⟨l,l_len⟩ a := by {
have h : n < (l ++ [a]).length :=
by {rw[list.length_append,list.length,list.length,zero_add,l_len],
exact n.lt_succ_self,},
have h' : (l ++ [a]).nth n = some a := l_len ▸ (l.nth_concat_length a),
injection ((list.nth_le_nth h).symm.trans h'),}
lemma concat_trim_last : ∀ (v : vector α (n + 1)), v.trim.concat v.last = v
| ⟨l,l_len⟩ := subtype.eq $ begin
change (l.take n) ++ [l.nth_le n _] = l,
let h := list.take_append_drop n l,
let h' := list.drop_eq_last l_len,
rw[h'] at h,
exact h,
end
def cons_inj (n : ℕ) (a : α) : vector α n ↪ vector α (n + 1) := {
to_fun := vector.cons a,
inj := λ ⟨l₀,l₀_len⟩ ⟨l₁,l₁_len⟩ e,
begin
apply subtype.eq,
dsimp[vector.cons] at e,
let f : vector α n → list α := @vector.to_list α n,
let e' : list.cons a l₀ = list.cons a l₁ := vector.veq_of_eq e,
injection e' with em ev
end
}
def concat_inj (n : ℕ) (a : α) : vector α n ↪ vector α (n + 1) := {
to_fun := λ v, v.concat a,
inj := λ ⟨l₀,l₀_len⟩ ⟨l₁,l₁_len⟩ e,
begin
apply subtype.eq,
replace e := vector.veq_of_eq e,
exact list.append_inj_right e (l₀_len.trans l₁_len.symm),
end
}
section prod
variable [monoid α]
variable [add_monoid β]
@[to_additive vector.sum]
def prod (v : vector α n) : α := v.val.prod
@[to_additive vector.sum_eq_val_sum]
lemma prod_eq_val_prod (v : vector α n) : v.prod = v.val.prod := rfl
@[to_additive vector.sum_cons]
lemma prod_cons : ∀ (a : α) (v : vector α n),
(a :: v).prod = a * v.prod
| a ⟨l,l_len⟩ := list.prod_cons
@[to_additive vector.sum_append]
lemma prod_append : ∀ (v : vector α n) (w : vector α m), (vector.append v w).prod = v.prod * w.prod
| ⟨l,l_len⟩ ⟨k,k_len⟩ := list.prod_append
lemma prod_concat (n : ℕ) : ∀ (v : vector α n) (a : α),
(v.concat a).prod = v.prod * a
| ⟨l,l_len⟩ a := by {rw[concat],change (l ++ [a]).prod = l.prod * a,
rw[list.prod_append,list.prod_cons,list.prod_nil,mul_one],}
lemma sum_concat (n : ℕ) : ∀ (v : vector β n) (b : β),
(v.concat b).sum = v.sum + b
| ⟨l,l_len⟩ b := by {rw[concat],change (l ++ [b]).sum = l.sum + b,
rw[list.sum_append,list.sum_cons,list.sum_nil,add_zero],}
end prod
end vector
|
b74283adfcda61c9279411859894d38094d7d70a | b7f22e51856f4989b970961f794f1c435f9b8f78 | /tests/lean/substvars2.hlean | 6a4165060d8f65008f6961cd39d19c59b6b6d21f | [
"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 | 369 | hlean | inductive list (A : Type) :=
| nil : list A
| cons : A → list A → list A
open nat prod
example (A B : Type) (d c : nat) (h₀ : c = 0) (a : A) (b : list B) (h₁ : A = list B) (h₂ : eq.rec_on h₁ a = @list.nil B) (h₃ : d = c) (h₄ : d + 1 = d + 2)
: b = eq.rec_on h₁ a × c = 1:=
begin
substvars,
state,
injection h₄,
contradiction
end
|
8fb766659e238a4b4beb304d592d617eb5520e18 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/data/finsupp/ne_locus.lean | 2dfb2a4d6d19bb20c44701e8ace94ff39af53326 | [
"Apache-2.0"
] | permissive | jcommelin/mathlib | d8456447c36c176e14d96d9e76f39841f69d2d9b | ee8279351a2e434c2852345c51b728d22af5a156 | refs/heads/master | 1,664,782,136,488 | 1,663,638,983,000 | 1,663,638,983,000 | 132,563,656 | 0 | 0 | Apache-2.0 | 1,663,599,929,000 | 1,525,760,539,000 | Lean | UTF-8 | Lean | false | false | 5,058 | lean | /-
Copyright (c) 2022 Damiano Testa. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Damiano Testa
-/
import data.finsupp.defs
/-!
# Locus of unequal values of finitely supported functions
Let `α N` be two Types, assume that `N` has a `0` and let `f g : α →₀ N` be finitely supported
functions.
## Main definition
* `finsupp.ne_locus f g : finset α`, the finite subset of `α` where `f` and `g` differ.
In the case in which `N` is an additive group, `finsupp.ne_locus f g` coincides with
`finsupp.support (f - g)`.
-/
variables {α M N P : Type*}
namespace finsupp
variable [decidable_eq α]
section N_has_zero
variables [decidable_eq N] [has_zero N] (f g : α →₀ N)
/-- Given two finitely supported functions `f g : α →₀ N`, `finsupp.ne_locus f g` is the `finset`
where `f` and `g` differ. This generalizes `(f - g).support` to situations without subtraction. -/
def ne_locus (f g : α →₀ N) : finset α :=
(f.support ∪ g.support).filter (λ x, f x ≠ g x)
@[simp] lemma mem_ne_locus {f g : α →₀ N} {a : α} : a ∈ f.ne_locus g ↔ f a ≠ g a :=
by simpa only [ne_locus, finset.mem_filter, finset.mem_union, mem_support_iff,
and_iff_right_iff_imp] using ne.ne_or_ne _
lemma not_mem_ne_locus {f g : α →₀ N} {a : α} : a ∉ f.ne_locus g ↔ f a = g a :=
mem_ne_locus.not.trans not_ne_iff
@[simp] lemma coe_ne_locus : ↑(f.ne_locus g) = {x | f x ≠ g x} :=
by { ext, exact mem_ne_locus }
@[simp] lemma ne_locus_eq_empty {f g : α →₀ N} : f.ne_locus g = ∅ ↔ f = g :=
⟨λ h, ext (λ a, not_not.mp (mem_ne_locus.not.mp (finset.eq_empty_iff_forall_not_mem.mp h a))),
λ h, h ▸ by simp only [ne_locus, ne.def, eq_self_iff_true, not_true, finset.filter_false]⟩
@[simp] lemma nonempty_ne_locus_iff {f g : α →₀ N} : (f.ne_locus g).nonempty ↔ f ≠ g :=
finset.nonempty_iff_ne_empty.trans ne_locus_eq_empty.not
lemma ne_locus_comm : f.ne_locus g = g.ne_locus f :=
by simp_rw [ne_locus, finset.union_comm, ne_comm]
@[simp]
lemma ne_locus_zero_right : f.ne_locus 0 = f.support :=
by { ext, rw [mem_ne_locus, mem_support_iff, coe_zero, pi.zero_apply] }
@[simp]
lemma ne_locus_zero_left : (0 : α →₀ N).ne_locus f = f.support :=
(ne_locus_comm _ _).trans (ne_locus_zero_right _)
end N_has_zero
section ne_locus_and_maps
lemma subset_map_range_ne_locus [decidable_eq N] [has_zero N] [decidable_eq M] [has_zero M]
(f g : α →₀ N) {F : N → M} (F0 : F 0 = 0) :
(f.map_range F F0).ne_locus (g.map_range F F0) ⊆ f.ne_locus g :=
λ x, by simpa only [mem_ne_locus, map_range_apply, not_imp_not] using congr_arg F
lemma zip_with_ne_locus_eq_left [decidable_eq N] [has_zero M] [decidable_eq P] [has_zero P]
[has_zero N] {F : M → N → P} (F0 : F 0 0 = 0)
(f : α →₀ M) (g₁ g₂ : α →₀ N) (hF : ∀ f, function.injective (λ g, F f g)) :
(zip_with F F0 f g₁).ne_locus (zip_with F F0 f g₂) = g₁.ne_locus g₂ :=
by { ext, simpa only [mem_ne_locus] using (hF _).ne_iff }
lemma zip_with_ne_locus_eq_right [decidable_eq M] [has_zero M] [decidable_eq P] [has_zero P]
[has_zero N] {F : M → N → P} (F0 : F 0 0 = 0)
(f₁ f₂ : α →₀ M) (g : α →₀ N) (hF : ∀ g, function.injective (λ f, F f g)) :
(zip_with F F0 f₁ g).ne_locus (zip_with F F0 f₂ g) = f₁.ne_locus f₂ :=
by { ext, simpa only [mem_ne_locus] using (hF _).ne_iff }
lemma map_range_ne_locus_eq [decidable_eq N] [decidable_eq M] [has_zero M] [has_zero N]
(f g : α →₀ N) {F : N → M} (F0 : F 0 = 0) (hF : function.injective F) :
(f.map_range F F0).ne_locus (g.map_range F F0) = f.ne_locus g :=
by { ext, simpa only [mem_ne_locus] using hF.ne_iff }
end ne_locus_and_maps
section cancel_and_group
variables [decidable_eq N]
@[simp] lemma add_ne_locus_add_eq_left [add_left_cancel_monoid N] (f g h : α →₀ N) :
(f + g).ne_locus (f + h) = g.ne_locus h :=
zip_with_ne_locus_eq_left _ _ _ _ add_right_injective
@[simp] lemma add_ne_locus_add_eq_right [add_right_cancel_monoid N] (f g h : α →₀ N) :
(f + h).ne_locus (g + h) = f.ne_locus g :=
zip_with_ne_locus_eq_right _ _ _ _ add_left_injective
@[simp] lemma neg_ne_locus_neg [add_group N] (f g : α →₀ N) : (- f).ne_locus (- g) = f.ne_locus g :=
map_range_ne_locus_eq _ _ neg_zero neg_injective
lemma ne_locus_neg [add_group N] (f g : α →₀ N) : (- f).ne_locus g = f.ne_locus (- g) :=
by rw [← neg_ne_locus_neg _ _, neg_neg]
lemma ne_locus_eq_support_sub [add_group N] (f g : α →₀ N) :
f.ne_locus g = (f - g).support :=
by rw [← add_ne_locus_add_eq_right _ _ (- g), add_right_neg, ne_locus_zero_right, sub_eq_add_neg]
@[simp] lemma sub_ne_locus_sub_eq_left [add_group N] (f g h : α →₀ N) :
(f - g).ne_locus (f - h) = g.ne_locus h :=
zip_with_ne_locus_eq_left _ _ _ _ (λ fn, sub_right_injective)
@[simp] lemma sub_ne_locus_sub_eq_right [add_group N] (f g h : α →₀ N) :
(f - h).ne_locus (g - h) = f.ne_locus g :=
zip_with_ne_locus_eq_right _ _ _ _ (λ hn, sub_left_injective)
end cancel_and_group
end finsupp
|
31df1a39822a78f96fababe887b4150a4930734e | 367134ba5a65885e863bdc4507601606690974c1 | /src/algebra/group/prod.lean | 365408f9967fc2b15e35d54248949303106adaf9 | [
"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 | 10,930 | lean | /-
Copyright (c) 2020 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Simon Hudon, Patrick Massot, Yury Kudryashov
-/
import algebra.group.hom
import data.equiv.mul_add
import data.prod
/-!
# Monoid, group etc structures on `M × N`
In this file we define one-binop (`monoid`, `group` etc) structures on `M × N`. We also prove
trivial `simp` lemmas, and define the following operations on `monoid_hom`s:
* `fst M N : M × N →* M`, `snd M N : M × N →* N`: projections `prod.fst` and `prod.snd`
as `monoid_hom`s;
* `inl M N : M →* M × N`, `inr M N : N →* M × N`: inclusions of first/second monoid
into the product;
* `f.prod g : `M →* N × P`: sends `x` to `(f x, g x)`;
* `f.coprod g : M × N →* P`: sends `(x, y)` to `f x * g y`;
* `f.prod_map g : M × N → M' × N'`: `prod.map f g` as a `monoid_hom`,
sends `(x, y)` to `(f x, g y)`.
-/
variables {A : Type*} {B : Type*} {G : Type*} {H : Type*} {M : Type*} {N : Type*} {P : Type*}
namespace prod
@[to_additive]
instance [has_mul M] [has_mul N] : has_mul (M × N) := ⟨λ p q, ⟨p.1 * q.1, p.2 * q.2⟩⟩
@[simp, to_additive]
lemma fst_mul [has_mul M] [has_mul N] (p q : M × N) : (p * q).1 = p.1 * q.1 := rfl
@[simp, to_additive]
lemma snd_mul [has_mul M] [has_mul N] (p q : M × N) : (p * q).2 = p.2 * q.2 := rfl
@[simp, to_additive]
lemma mk_mul_mk [has_mul M] [has_mul N] (a₁ a₂ : M) (b₁ b₂ : N) :
(a₁, b₁) * (a₂, b₂) = (a₁ * a₂, b₁ * b₂) := rfl
@[to_additive]
instance [has_one M] [has_one N] : has_one (M × N) := ⟨(1, 1)⟩
@[simp, to_additive]
lemma fst_one [has_one M] [has_one N] : (1 : M × N).1 = 1 := rfl
@[simp, to_additive]
lemma snd_one [has_one M] [has_one N] : (1 : M × N).2 = 1 := rfl
@[to_additive]
lemma one_eq_mk [has_one M] [has_one N] : (1 : M × N) = (1, 1) := rfl
@[simp, to_additive]
lemma mk_eq_one [has_one M] [has_one N] {x : M} {y : N} : (x, y) = 1 ↔ x = 1 ∧ y = 1 :=
mk.inj_iff
@[to_additive]
lemma fst_mul_snd [monoid M] [monoid N] (p : M × N) :
(p.fst, 1) * (1, p.snd) = p :=
ext (mul_one p.1) (one_mul p.2)
@[to_additive]
instance [has_inv M] [has_inv N] : has_inv (M × N) := ⟨λp, (p.1⁻¹, p.2⁻¹)⟩
@[simp, to_additive]
lemma fst_inv [has_inv G] [has_inv H] (p : G × H) : (p⁻¹).1 = (p.1)⁻¹ := rfl
@[simp, to_additive]
lemma snd_inv [has_inv G] [has_inv H] (p : G × H) : (p⁻¹).2 = (p.2)⁻¹ := rfl
@[simp, to_additive]
lemma inv_mk [has_inv G] [has_inv H] (a : G) (b : H) : (a, b)⁻¹ = (a⁻¹, b⁻¹) := rfl
@[to_additive]
instance [has_div M] [has_div N] : has_div (M × N) := ⟨λ p q, ⟨p.1 / q.1, p.2 / q.2⟩⟩
@[simp] lemma fst_sub [add_group A] [add_group B] (a b : A × B) : (a - b).1 = a.1 - b.1 := rfl
@[simp] lemma snd_sub [add_group A] [add_group B] (a b : A × B) : (a - b).2 = a.2 - b.2 := rfl
@[simp] lemma mk_sub_mk [add_group A] [add_group B] (x₁ x₂ : A) (y₁ y₂ : B) :
(x₁, y₁) - (x₂, y₂) = (x₁ - x₂, y₁ - y₂) := rfl
@[to_additive]
instance [semigroup M] [semigroup N] : semigroup (M × N) :=
{ mul_assoc := assume a b c, mk.inj_iff.mpr ⟨mul_assoc _ _ _, mul_assoc _ _ _⟩,
.. prod.has_mul }
@[to_additive]
instance [monoid M] [monoid N] : monoid (M × N) :=
{ one_mul := assume a, prod.rec_on a $ λa b, mk.inj_iff.mpr ⟨one_mul _, one_mul _⟩,
mul_one := assume a, prod.rec_on a $ λa b, mk.inj_iff.mpr ⟨mul_one _, mul_one _⟩,
.. prod.semigroup, .. prod.has_one }
@[to_additive]
instance [group G] [group H] : group (G × H) :=
{ mul_left_inv := assume a, mk.inj_iff.mpr ⟨mul_left_inv _, mul_left_inv _⟩,
div_eq_mul_inv := λ a b, mk.inj_iff.mpr ⟨div_eq_mul_inv _ _, div_eq_mul_inv _ _⟩,
.. prod.monoid, .. prod.has_inv, .. prod.has_div }
@[to_additive]
instance [comm_semigroup G] [comm_semigroup H] : comm_semigroup (G × H) :=
{ mul_comm := assume a b, mk.inj_iff.mpr ⟨mul_comm _ _, mul_comm _ _⟩,
.. prod.semigroup }
@[to_additive]
instance [left_cancel_semigroup G] [left_cancel_semigroup H] :
left_cancel_semigroup (G × H) :=
{ mul_left_cancel := λ a b c h, prod.ext (mul_left_cancel (prod.ext_iff.1 h).1)
(mul_left_cancel (prod.ext_iff.1 h).2),
.. prod.semigroup }
@[to_additive]
instance [right_cancel_semigroup G] [right_cancel_semigroup H] :
right_cancel_semigroup (G × H) :=
{ mul_right_cancel := λ a b c h, prod.ext (mul_right_cancel (prod.ext_iff.1 h).1)
(mul_right_cancel (prod.ext_iff.1 h).2),
.. prod.semigroup }
@[to_additive]
instance [comm_monoid M] [comm_monoid N] : comm_monoid (M × N) :=
{ .. prod.comm_semigroup, .. prod.monoid }
@[to_additive]
instance [comm_group G] [comm_group H] : comm_group (G × H) :=
{ .. prod.comm_semigroup, .. prod.group }
end prod
namespace monoid_hom
variables (M N) [monoid M] [monoid N]
/-- Given monoids `M`, `N`, the natural projection homomorphism from `M × N` to `M`.-/
@[to_additive "Given additive monoids `A`, `B`, the natural projection homomorphism
from `A × B` to `A`"]
def fst : M × N →* M := ⟨prod.fst, rfl, λ _ _, rfl⟩
/-- Given monoids `M`, `N`, the natural projection homomorphism from `M × N` to `N`.-/
@[to_additive "Given additive monoids `A`, `B`, the natural projection homomorphism
from `A × B` to `B`"]
def snd : M × N →* N := ⟨prod.snd, rfl, λ _ _, rfl⟩
/-- Given monoids `M`, `N`, the natural inclusion homomorphism from `M` to `M × N`. -/
@[to_additive "Given additive monoids `A`, `B`, the natural inclusion homomorphism
from `A` to `A × B`."]
def inl : M →* M × N :=
⟨λ x, (x, 1), rfl, λ _ _, prod.ext rfl (one_mul 1).symm⟩
/-- Given monoids `M`, `N`, the natural inclusion homomorphism from `N` to `M × N`. -/
@[to_additive "Given additive monoids `A`, `B`, the natural inclusion homomorphism
from `B` to `A × B`."]
def inr : N →* M × N :=
⟨λ y, (1, y), rfl, λ _ _, prod.ext (one_mul 1).symm rfl⟩
variables {M N}
@[simp, to_additive] lemma coe_fst : ⇑(fst M N) = prod.fst := rfl
@[simp, to_additive] lemma coe_snd : ⇑(snd M N) = prod.snd := rfl
@[simp, to_additive] lemma inl_apply (x) : inl M N x = (x, 1) := rfl
@[simp, to_additive] lemma inr_apply (y) : inr M N y = (1, y) := rfl
@[simp, to_additive] lemma fst_comp_inl : (fst M N).comp (inl M N) = id M := rfl
@[simp, to_additive] lemma snd_comp_inl : (snd M N).comp (inl M N) = 1 := rfl
@[simp, to_additive] lemma fst_comp_inr : (fst M N).comp (inr M N) = 1 := rfl
@[simp, to_additive] lemma snd_comp_inr : (snd M N).comp (inr M N) = id N := rfl
section prod
variable [monoid P]
/-- Combine two `monoid_hom`s `f : M →* N`, `g : M →* P` into `f.prod g : M →* N × P`
given by `(f.prod g) x = (f x, g x)` -/
@[to_additive prod "Combine two `add_monoid_hom`s `f : M →+ N`, `g : M →+ P` into
`f.prod g : M →+ N × P` given by `(f.prod g) x = (f x, g x)`"]
protected def prod (f : M →* N) (g : M →* P) : M →* N × P :=
{ to_fun := λ x, (f x, g x),
map_one' := prod.ext f.map_one g.map_one,
map_mul' := λ x y, prod.ext (f.map_mul x y) (g.map_mul x y) }
@[simp, to_additive prod_apply]
lemma prod_apply (f : M →* N) (g : M →* P) (x) : f.prod g x = (f x, g x) := rfl
@[simp, to_additive fst_comp_prod]
lemma fst_comp_prod (f : M →* N) (g : M →* P) : (fst N P).comp (f.prod g) = f :=
ext $ λ x, rfl
@[simp, to_additive snd_comp_prod]
lemma snd_comp_prod (f : M →* N) (g : M →* P) : (snd N P).comp (f.prod g) = g :=
ext $ λ x, rfl
@[simp, to_additive prod_unique]
lemma prod_unique (f : M →* N × P) :
((fst N P).comp f).prod ((snd N P).comp f) = f :=
ext $ λ x, by simp only [prod_apply, coe_fst, coe_snd, comp_apply, prod.mk.eta]
end prod
section prod_map
variables {M' : Type*} {N' : Type*} [monoid M'] [monoid N'] [monoid P]
(f : M →* M') (g : N →* N')
/-- `prod.map` as a `monoid_hom`. -/
@[to_additive prod_map "`prod.map` as an `add_monoid_hom`"]
def prod_map : M × N →* M' × N' := (f.comp (fst M N)).prod (g.comp (snd M N))
@[to_additive prod_map_def]
lemma prod_map_def : prod_map f g = (f.comp (fst M N)).prod (g.comp (snd M N)) := rfl
@[simp, to_additive coe_prod_map]
lemma coe_prod_map : ⇑(prod_map f g) = prod.map f g := rfl
@[to_additive prod_comp_prod_map]
lemma prod_comp_prod_map (f : P →* M) (g : P →* N) (f' : M →* M') (g' : N →* N') :
(f'.prod_map g').comp (f.prod g) = (f'.comp f).prod (g'.comp g) :=
rfl
end prod_map
section coprod
variables [comm_monoid P] (f : M →* P) (g : N →* P)
/-- Coproduct of two `monoid_hom`s with the same codomain:
`f.coprod g (p : M × N) = f p.1 * g p.2`. -/
@[to_additive "Coproduct of two `add_monoid_hom`s with the same codomain:
`f.coprod g (p : M × N) = f p.1 + g p.2`."]
def coprod : M × N →* P := f.comp (fst M N) * g.comp (snd M N)
@[simp, to_additive]
lemma coprod_apply (p : M × N) : f.coprod g p = f p.1 * g p.2 := rfl
@[simp, to_additive]
lemma coprod_comp_inl : (f.coprod g).comp (inl M N) = f :=
ext $ λ x, by simp [coprod_apply]
@[simp, to_additive]
lemma coprod_comp_inr : (f.coprod g).comp (inr M N) = g :=
ext $ λ x, by simp [coprod_apply]
@[simp, to_additive] lemma coprod_unique (f : M × N →* P) :
(f.comp (inl M N)).coprod (f.comp (inr M N)) = f :=
ext $ λ x, by simp [coprod_apply, inl_apply, inr_apply, ← map_mul]
@[simp, to_additive] lemma coprod_inl_inr {M N : Type*} [comm_monoid M] [comm_monoid N] :
(inl M N).coprod (inr M N) = id (M × N) :=
coprod_unique (id $ M × N)
lemma comp_coprod {Q : Type*} [comm_monoid Q] (h : P →* Q) (f : M →* P) (g : N →* P) :
h.comp (f.coprod g) = (h.comp f).coprod (h.comp g) :=
ext $ λ x, by simp
end coprod
end monoid_hom
namespace mul_equiv
variables {M N} [monoid M] [monoid N]
/-- The equivalence between `M × N` and `N × M` given by swapping the components
is multiplicative. -/
@[to_additive prod_comm "The equivalence between `M × N` and `N × M` given by swapping the
components is additive."]
def prod_comm : M × N ≃* N × M :=
{ map_mul' := λ ⟨x₁, y₁⟩ ⟨x₂, y₂⟩, rfl, ..equiv.prod_comm M N }
@[simp, to_additive coe_prod_comm] lemma coe_prod_comm :
⇑(prod_comm : M × N ≃* N × M) = prod.swap := rfl
@[simp, to_additive coe_prod_comm_symm] lemma coe_prod_comm_symm :
⇑((prod_comm : M × N ≃* N × M).symm) = prod.swap := rfl
/-- The monoid equivalence between units of a product of two monoids, and the product of the
units of each monoid. -/
@[to_additive prod_add_units "The additive monoid equivalence between additive units of a product
of two additive monoids, and the product of the additive units of each additive monoid."]
def prod_units : units (M × N) ≃* units M × units N :=
{ to_fun := (units.map (monoid_hom.fst M N)).prod (units.map (monoid_hom.snd M N)),
inv_fun := λ u, ⟨(u.1, u.2), (↑u.1⁻¹, ↑u.2⁻¹), by simp, by simp⟩,
left_inv := λ u, by simp,
right_inv := λ ⟨u₁, u₂⟩, by simp [units.map],
map_mul' := monoid_hom.map_mul _ }
end mul_equiv
|
1c56556a681058d0e0d9a2e71527c20e7eba17d5 | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/interp.lean | f896a36bc5daaeef9cd389af63868944aa5cd0e7 | [
"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 | 775 | lean | open bool nat
open function
inductive univ
| ubool : univ
| unat : univ
| uarrow : univ → univ → univ
open univ
attribute [reducible]
definition interp : univ → Type
| ubool := bool
| unat := nat
| (uarrow fr to) := interp fr → interp to
definition foo : Π (u : univ) (el : interp u), interp u
| ubool tt := ff
| ubool ff := tt
| unat n := succ n
| (uarrow fr to) f := λ x : interp fr, f (foo fr x)
definition is_even : nat → bool
| 0 := tt
| (succ n) := bnot (is_even n)
example : foo unat (10:nat) = (11:nat) := rfl
example : foo ubool tt = ff := rfl
example : foo (uarrow unat ubool) (λ x : nat, is_even x) 3 = tt := rfl
example : foo (uarrow unat ubool) (λ x : nat, is_even x) 4 = ff := rfl
|
65ae4c3149e02a7998f51024222c9e1a1f36854a | a9d0fb7b0e4f802bd3857b803e6c5c23d87fef91 | /tests/lean/quot_bug.lean | 5ee072047f0fa9b0771b06690497343809f3838d | [
"Apache-2.0"
] | permissive | soonhokong/lean-osx | 4a954262c780e404c1369d6c06516161d07fcb40 | 3670278342d2f4faa49d95b46d86642d7875b47c | refs/heads/master | 1,611,410,334,552 | 1,474,425,686,000 | 1,474,425,686,000 | 12,043,103 | 5 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 226 | lean | open quot
variables {A : Type} {B : A → Type}
variable f : Π a : A, B a
eval λ x, quot.lift_on ⟦f⟧ (λf : (Πx : A, B x), f) _ x
example (x : A) : quot.lift_on ⟦f⟧ (λf : (Πx : A, B x), f) sorry x = f x :=
rfl
|
988559f5fe6d5f1d7001c64120261e21860dfab4 | e514e8b939af519a1d5e9b30a850769d058df4e9 | /src/tactic/rewrite_search/strategy/pexplore.lean | c327e861e6abb01aeb9b2a38d9604ace8ec35fd4 | [] | no_license | semorrison/lean-rewrite-search | dca317c5a52e170fb6ffc87c5ab767afb5e3e51a | e804b8f2753366b8957be839908230ee73f9e89f | refs/heads/master | 1,624,051,754,485 | 1,614,160,817,000 | 1,614,160,817,000 | 162,660,605 | 0 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 10,207 | lean | import tactic.iconfig
import tactic.rewrite_search.core
import tactic.rewrite_search.module
open tactic.rewrite_search
open tactic.rewrite_search.bound_progress
namespace tactic.rewrite_search.strategy.pexplore
structure pexplore_config :=
(pop_size : ℕ := 100)
(pop_alternate : bool := tt)
structure pair_stream :=
(last_side : side)
(its : sided_pair rewriterator)
inductive ipair
| unresolved (p : pair) (de : table_ref) : ipair
| resolved (p : pair) (de : table_ref) (ps : pair_stream) : ipair
def ipair.pair : ipair → pair
| (ipair.unresolved p de) := p
| (ipair.resolved p de _) := p
def ipair.de : ipair → table_ref
| (ipair.unresolved p de) := de
| (ipair.resolved p de _) := de
def ipair.to_string : ipair → string
| (ipair.unresolved p de) := to_string p ++ "@" ++ to_string de ++ "?"
| (ipair.resolved p de _) := to_string p ++ "@" ++ to_string de ++ "!"
instance has_to_string : has_to_string ipair := ⟨ipair.to_string⟩
structure pexplore_state :=
(conf : pexplore_config)
(initial : ipair)
(interesting_pairs : list ipair)
(done_pairs : list pair)
variables {β γ δ : Type} (m : metric pexplore_state β γ δ) (g : search_state pexplore_state β γ δ)
namespace pair_stream
meta def from_vertices (vl vr : vertex) : tactic (search_state pexplore_state β γ δ × pair_stream) := do
(g, lhs_it) ← g.visit_vertex vl,
(g, rhs_it) ← g.visit_vertex vr,
return (g, ⟨side.L, ⟨lhs_it, rhs_it⟩⟩)
meta def from_estimate (de : dist_estimate γ) : tactic (search_state pexplore_state β γ δ × pair_stream) := do
(vl, vr) ← g.get_estimate_verts de,
from_vertices g vl vr
meta instance has_to_format_pair : has_to_format pair := ⟨λ p, to_string p⟩
meta instance has_to_format_option_pair : has_to_format (option pair) := ⟨λ op, match op with | none := "none" | some p := to_string p end⟩
meta def read_side (ps : pair_stream) (g : search_state pexplore_state β γ δ) (p : pair) (s : side) : tactic (search_state pexplore_state β γ δ × pair_stream × option pair) := do
(g, it, nxt) ← (ps.its.get s).next g,
let newp : option pair := match nxt with
| some (v, e) := some ⟨p.get s.other, v.id⟩
| none := none
end,
(vl, vr) ← g.lookup_pair p,
return (g, {ps with last_side := s, its := ps.its.set s it}, newp)
meta def read (ps : pair_stream) (g : search_state pexplore_state β γ δ) (p : pair) : tactic (search_state pexplore_state β γ δ × pair_stream × option pair) := do
let next_side := if g.strat_state.conf.pop_alternate then ps.last_side.other else ps.last_side,
(g, ps, ret) ← ps.read_side g p next_side,
match ret with
| some _ := return (g, ps, ret)
| none := ps.read_side g p next_side.other
end
end pair_stream
-- updates rival's estimate tryg to beat candidate's estimate, stoppg if we do or we can'tbfs
-- go any further. We return true if we were able to beat candidate.
private meta def try_to_beat (candidate rival : dist_estimate γ) : tactic (search_state pexplore_state β γ δ × dist_estimate γ × bool) :=
let cbnd := candidate.bnd.bound in
match rival.bnd with
| exactly n _ := return (g, rival, n <= cbnd)
| at_least n p := do
(g, attempt) ← g.improve_estimate_over m cbnd rival,
return (g, attempt, attempt.bnd.bound < cbnd)
end
-- First is closer
private meta def sort_most_interesting : search_state pexplore_state β γ δ → ipair × dist_estimate γ → ipair × dist_estimate γ → tactic (search_state pexplore_state β γ δ × (ipair × dist_estimate γ) × (ipair × dist_estimate γ))
| g (a, a_de) (b, b_de) := do
(g, new_b_de, better) ← try_to_beat m g a_de b_de,
match better with
-- b is guarenteed closer, so return it:
| tt := return (g, (b, new_b_de), (a, a_de))
-- otherwise:
| ff := match a_de.bnd with
-- b is further than the current estimate for a and the estimate for a is exact:
| exactly k _ := return (g, (a, a_de), (b, new_b_de))
-- or, b is futher than the current estimate for a but a might actually be worse, so check:
| at_least k p := sort_most_interesting g (b, new_b_de) (a, a_de)
end
end
private meta def find_most_interesting_aux : search_state pexplore_state β γ δ → ipair × dist_estimate γ → list ipair → list ipair → tactic (search_state pexplore_state β γ δ × ipair × list ipair)
| g (curr_best, curr_de) seen [] := return (g, curr_best, seen)
| g (curr_best, curr_de) seen (candidate :: rest) := do
candidate_de ← g.estimates.get candidate.de,
(g, (better, better_de), (worse, worse_de)) ← sort_most_interesting m g (curr_best, curr_de) (candidate, candidate_de),
find_most_interesting_aux g (better, better_de) (worse :: seen) rest
meta def find_most_interesting : tactic (search_state pexplore_state β γ δ × option ipair × list ipair) :=
match g.strat_state.interesting_pairs with
| [] := return (g, none, [])
| (a :: rest) := do
a_de ← g.estimates.get a.de,
(g, best, others) ← find_most_interesting_aux m g (a, a_de) [] rest,
return (g, some best, others)
end
meta def resolve_ipair : ipair → tactic (search_state pexplore_state β γ δ × ipair)
| (ipair.unresolved p ref) := do
de ← g.estimates.get ref,
(g, _) ← g.try_unify de.to_pair,
(g, ps) ← pair_stream.from_estimate g de,
return (g, ipair.resolved p ref ps)
| ip := return (g, ip)
meta def pop_ipairs_aux : search_state pexplore_state β γ δ → metric pexplore_state β γ δ → ℕ → ipair → tactic (search_state pexplore_state β γ δ × ipair × list ipair)
| g m 0 ip := return (g, ip, [])
| g m pop_size (ipair.unresolved p ref) := do
(g, ip) ← resolve_ipair g (ipair.unresolved p ref),
pop_ipairs_aux g m pop_size ip
| g m pop_size (ipair.resolved p ref ps) := do
(g, ps, nxt) ← ps.read g p,
let ip := ipair.resolved p ref ps,
match nxt with
| none := return (g.mutate_strat {g.strat_state with done_pairs := (p :: g.strat_state.done_pairs)}, ip, [])
| some nxt := do
match g.estimates.find (λ de, nxt = de.to_pair ∨ (nxt = de.to_pair.flip)) with
| none := do
(g, ref) ← g.alloc_estimate m nxt,
let newip := ipair.unresolved nxt ref,
(g, ip, others) ← pop_ipairs_aux g m (pop_size - 1) ip,
return (g, ipair.resolved p ref ps, list.cons newip others)
| some de := pop_ipairs_aux g m pop_size ip
end
end
meta def pop_ipairs (pop_size : ℕ) (ip : ipair) : tactic (search_state pexplore_state β γ δ × ipair × list ipair) := do
(g, ip, new) ← pop_ipairs_aux g m pop_size ip,
return (g, ip, new)
meta def pexplore_init : tactic (init_result pexplore_state) :=
init_result.pure ⟨{}, ipair.unresolved pair.null table_ref.null, [], []⟩
meta def pexplore_startup (conf : pexplore_config) (m : metric pexplore_state β γ δ) (l r : vertex) : tactic (search_state pexplore_state β γ δ) := do
let p : pair := ⟨l.id, r.id⟩,
(g, ref) ← g.alloc_estimate m p,
let initial := ipair.unresolved p ref,
return $ g.mutate_strat ⟨{}, initial, [initial], []⟩
meta def pexplore_startup_conf (res : iconfig.result) (g : search_state pexplore_state β γ δ) (m : metric pexplore_state β γ δ) (l r : vertex) : tactic (search_state pexplore_state β γ δ) := do
conf ← res.struct `tactic.rewrite_search.strategy.pexplore.pexplore_config pexplore_config,
pexplore_startup g conf m l r
-- TODO find our "best" pairs, corresponding to seen distance estimates within a certain
-- threshold of the absolute best, and return them.
meta def get_best_pairs : tactic (list pair) :=
return g.strat_state.done_pairs
meta def clear_vertex (v : vertex) : vertex :=
{v with rw_prog := none, rws := table.create, rw_front := table_ref.first, adj := table.create}
meta def pexplore_step : search_state pexplore_state β γ δ → metric pexplore_state β γ δ → ℕ → tactic (search_state pexplore_state β γ δ × status)
| g m itr := do
(g, best, others) ← find_most_interesting m g,
match (best, others) with
| (none, []) := do
bests ← get_best_pairs g,
(g, success) ← g.be_desperate bests,
if ¬success then
return (g, status.abort "all interesting pairs exhausted!")
else do
-- TODO Be smarter. Reset all rewriterators and just roll with the interesting pairs we have?
let initial := g.strat_state.initial,
-- FIXME this is a real hack: we currently use existance of an entry in the
-- distance estimate table to determine if we have seen a given interesting
-- pair before. This needs to change, and until then we have to do:
vl ← clear_vertex <$> g.vertices.get table_ref.first,
vr ← clear_vertex <$> g.vertices.get table_ref.first.next,
let g := {g with vertices := table.from_list [vl, vr], estimates := table.create},
g ← pexplore_startup g g.strat_state.conf m vl vr,
return (g, status.repeat)
| (none, _) := pexplore_step g m itr
| (some best, others) := do
(g, best, new) ← pop_ipairs m g g.strat_state.conf.pop_size best,
(new_head, s) ← pure $ match new with
| [] := ([], status.repeat)
| l := (l.concat best, status.continue)
end,
return (g.mutate_strat {g.strat_state with interesting_pairs := new_head.append others }, s)
end
end tactic.rewrite_search.strategy.pexplore
namespace tactic.rewrite_search.strategy
open tactic.rewrite_search.strategy.pexplore
meta def pexplore_cnst (conf : iconfig.result) :=
λ β γ δ, strategy.mk pexplore_init (@pexplore_startup_conf β γ δ conf) (@pexplore_step β γ δ)
meta def pexplore (conf : iconfig.result := iconfig.empty_result) : tactic expr :=
generic_arg `tactic.rewrite_search.strategy.pexplore_cnst `(conf)
section
iconfig_mk pexplore
iconfig_add_struct pexplore tactic.rewrite_search.strategy.pexplore.pexplore_config
meta def pexplore_cfg (_ : name) (cfg : iconfig pexplore) : cfgtactic unit := do
cfg ← iconfig.read cfg,
e ← tactic.to_expr $ ``(pexplore) $ pexpr.of_expr `(cfg),
iconfig.publish `strategy $ cfgopt.value.pexpr $ pexpr.of_expr e
iconfig_add rewrite_search [ strategy.pexplore : custom pexplore_cfg ]
end
end tactic.rewrite_search.strategy
|
6d2667d80e64ad743f154c60c40f8bd9e7932d38 | 97f752b44fd85ec3f635078a2dd125ddae7a82b6 | /tests/lean/defeq_simp_lemmas1.lean | 6679295feb34d48d4097df261a0a61ae46ffe8ae | [
"Apache-2.0"
] | permissive | tectronics/lean | ab977ba6be0fcd46047ddbb3c8e16e7c26710701 | f38af35e0616f89c6e9d7e3eb1d48e47ee666efe | refs/heads/master | 1,532,358,526,384 | 1,456,276,623,000 | 1,456,276,623,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 511 | lean | universe l
constants (A : Type.{l})
definition q (x : A) := x
definition h (x : A) : A := q x
definition g (x y : A) := h y
definition f (x y z : A) := g (g x y) z
definition d (x y z w : A) := f (f x y z) (f y z w) (f x w z)
definition h.def [defeq] (x : A) : h x = q x := rfl
definition g.def [defeq] (x y : A) : g x y = h y := rfl
definition f.def [defeq] (x y z : A) : f x y z = g (g x y) z := rfl
definition d.def [defeq] (x y z w : A) : d x y z w = f (f x y z) (f y z w) (f x w z) := rfl
print [defeq]
|
abcbc8f65e166c60b66dbca01e2d52241ab6bbf5 | bb31430994044506fa42fd667e2d556327e18dfe | /src/algebra/direct_sum/module.lean | a6c323a53a35f0089320c7963ebc810e72544e23 | [
"Apache-2.0"
] | permissive | sgouezel/mathlib | 0cb4e5335a2ba189fa7af96d83a377f83270e503 | 00638177efd1b2534fc5269363ebf42a7871df9a | refs/heads/master | 1,674,527,483,042 | 1,673,665,568,000 | 1,673,665,568,000 | 119,598,202 | 0 | 0 | null | 1,517,348,647,000 | 1,517,348,646,000 | null | UTF-8 | Lean | false | false | 14,878 | lean | /-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau
-/
import algebra.direct_sum.basic
import linear_algebra.dfinsupp
/-!
# Direct sum of modules
The first part of the file provides constructors for direct sums of modules. It provides a
construction of the direct sum using the universal property and proves its uniqueness
(`direct_sum.to_module.unique`).
The second part of the file covers the special case of direct sums of submodules of a fixed module
`M`. There is a canonical linear map from this direct sum to `M` (`direct_sum.coe_linear_map`), and
the construction is of particular importance when this linear map is an equivalence; that is, when
the submodules provide an internal decomposition of `M`. The property is defined more generally
elsewhere as `direct_sum.is_internal`, but its basic consequences on `submodule`s are established
in this file.
-/
universes u v w u₁
namespace direct_sum
open_locale direct_sum
section general
variables {R : Type u} [semiring R]
variables {ι : Type v} [dec_ι : decidable_eq ι]
include R
variables {M : ι → Type w} [Π i, add_comm_monoid (M i)] [Π i, module R (M i)]
instance : module R (⨁ i, M i) := dfinsupp.module
instance {S : Type*} [semiring S] [Π i, module S (M i)] [Π i, smul_comm_class R S (M i)] :
smul_comm_class R S (⨁ i, M i) := dfinsupp.smul_comm_class
instance {S : Type*} [semiring S] [has_smul R S] [Π i, module S (M i)]
[Π i, is_scalar_tower R S (M i)] :
is_scalar_tower R S (⨁ i, M i) := dfinsupp.is_scalar_tower
instance [Π i, module Rᵐᵒᵖ (M i)] [Π i, is_central_scalar R (M i)] :
is_central_scalar R (⨁ i, M i) := dfinsupp.is_central_scalar
lemma smul_apply (b : R) (v : ⨁ i, M i) (i : ι) :
(b • v) i = b • (v i) := dfinsupp.smul_apply _ _ _
include dec_ι
variables R ι M
/-- Create the direct sum given a family `M` of `R` modules indexed over `ι`. -/
def lmk : Π s : finset ι, (Π i : (↑s : set ι), M i.val) →ₗ[R] (⨁ i, M i) :=
dfinsupp.lmk
/-- Inclusion of each component into the direct sum. -/
def lof : Π i : ι, M i →ₗ[R] (⨁ i, M i) :=
dfinsupp.lsingle
lemma lof_eq_of (i : ι) (b : M i) : lof R ι M i b = of M i b := rfl
variables {ι M}
lemma single_eq_lof (i : ι) (b : M i) :
dfinsupp.single i b = lof R ι M i b := rfl
/-- Scalar multiplication commutes with direct sums. -/
theorem mk_smul (s : finset ι) (c : R) (x) : mk M s (c • x) = c • mk M s x :=
(lmk R ι M s).map_smul c x
/-- Scalar multiplication commutes with the inclusion of each component into the direct sum. -/
theorem of_smul (i : ι) (c : R) (x) : of M i (c • x) = c • of M i x :=
(lof R ι M i).map_smul c x
variables {R}
lemma support_smul [Π (i : ι) (x : M i), decidable (x ≠ 0)]
(c : R) (v : ⨁ i, M i) : (c • v).support ⊆ v.support := dfinsupp.support_smul _ _
variables {N : Type u₁} [add_comm_monoid N] [module R N]
variables (φ : Π i, M i →ₗ[R] N)
variables (R ι N φ)
/-- The linear map constructed using the universal property of the coproduct. -/
def to_module : (⨁ i, M i) →ₗ[R] N :=
dfinsupp.lsum ℕ φ
/-- Coproducts in the categories of modules and additive monoids commute with the forgetful functor
from modules to additive monoids. -/
lemma coe_to_module_eq_coe_to_add_monoid :
(to_module R ι N φ : (⨁ i, M i) → N) = to_add_monoid (λ i, (φ i).to_add_monoid_hom) :=
rfl
variables {ι N φ}
/-- The map constructed using the universal property gives back the original maps when
restricted to each component. -/
@[simp] lemma to_module_lof (i) (x : M i) : to_module R ι N φ (lof R ι M i x) = φ i x :=
to_add_monoid_of (λ i, (φ i).to_add_monoid_hom) i x
variables (ψ : (⨁ i, M i) →ₗ[R] N)
/-- Every linear map from a direct sum agrees with the one obtained by applying
the universal property to each of its components. -/
theorem to_module.unique (f : ⨁ i, M i) : ψ f = to_module R ι N (λ i, ψ.comp $ lof R ι M i) f :=
to_add_monoid.unique ψ.to_add_monoid_hom f
variables {ψ} {ψ' : (⨁ i, M i) →ₗ[R] N}
/-- Two `linear_map`s out of a direct sum are equal if they agree on the generators.
See note [partially-applied ext lemmas]. -/
@[ext]
theorem linear_map_ext ⦃ψ ψ' : (⨁ i, M i) →ₗ[R] N⦄
(H : ∀ i, ψ.comp (lof R ι M i) = ψ'.comp (lof R ι M i)) : ψ = ψ' :=
dfinsupp.lhom_ext' H
/--
The inclusion of a subset of the direct summands
into a larger subset of the direct summands, as a linear map.
-/
def lset_to_set (S T : set ι) (H : S ⊆ T) :
(⨁ (i : S), M i) →ₗ[R] (⨁ (i : T), M i) :=
to_module R _ _ $ λ i, lof R T (λ (i : subtype T), M i) ⟨i, H i.prop⟩
omit dec_ι
variables (ι M)
/-- Given `fintype α`, `linear_equiv_fun_on_fintype R` is the natural `R`-linear equivalence
between `⨁ i, M i` and `Π i, M i`. -/
@[simps apply] def linear_equiv_fun_on_fintype [fintype ι] :
(⨁ i, M i) ≃ₗ[R] (Π i, M i) :=
{ to_fun := coe_fn,
map_add' := λ f g, by { ext, simp only [add_apply, pi.add_apply] },
map_smul' := λ c f, by { ext, simp only [dfinsupp.coe_smul, ring_hom.id_apply] },
.. dfinsupp.equiv_fun_on_fintype }
variables {ι M}
@[simp] lemma linear_equiv_fun_on_fintype_lof [fintype ι] [decidable_eq ι] (i : ι) (m : M i) :
(linear_equiv_fun_on_fintype R ι M) (lof R ι M i m) = pi.single i m :=
begin
ext a,
change (dfinsupp.equiv_fun_on_fintype (lof R ι M i m)) a = _,
convert _root_.congr_fun (dfinsupp.equiv_fun_on_fintype_single i m) a,
end
@[simp] lemma linear_equiv_fun_on_fintype_symm_single [fintype ι] [decidable_eq ι]
(i : ι) (m : M i) :
(linear_equiv_fun_on_fintype R ι M).symm (pi.single i m) = lof R ι M i m :=
begin
ext a,
change (dfinsupp.equiv_fun_on_fintype.symm (pi.single i m)) a = _,
rw (dfinsupp.equiv_fun_on_fintype_symm_single i m),
refl
end
@[simp] lemma linear_equiv_fun_on_fintype_symm_coe [fintype ι] (f : ⨁ i, M i) :
(linear_equiv_fun_on_fintype R ι M).symm f = f :=
by { ext, simp [linear_equiv_fun_on_fintype], }
/-- The natural linear equivalence between `⨁ _ : ι, M` and `M` when `unique ι`. -/
protected def lid (M : Type v) (ι : Type* := punit) [add_comm_monoid M] [module R M]
[unique ι] :
(⨁ (_ : ι), M) ≃ₗ[R] M :=
{ .. direct_sum.id M ι,
.. to_module R ι M (λ i, linear_map.id) }
variables (ι M)
/-- The projection map onto one component, as a linear map. -/
def component (i : ι) : (⨁ i, M i) →ₗ[R] M i :=
dfinsupp.lapply i
variables {ι M}
lemma apply_eq_component (f : ⨁ i, M i) (i : ι) :
f i = component R ι M i f := rfl
@[ext] lemma ext {f g : ⨁ i, M i}
(h : ∀ i, component R ι M i f = component R ι M i g) : f = g :=
dfinsupp.ext h
lemma ext_iff {f g : ⨁ i, M i} : f = g ↔
∀ i, component R ι M i f = component R ι M i g :=
⟨λ h _, by rw h, ext R⟩
include dec_ι
@[simp] lemma lof_apply (i : ι) (b : M i) : ((lof R ι M i) b) i = b :=
dfinsupp.single_eq_same
@[simp] lemma component.lof_self (i : ι) (b : M i) :
component R ι M i ((lof R ι M i) b) = b :=
lof_apply R i b
lemma component.of (i j : ι) (b : M j) :
component R ι M i ((lof R ι M j) b) =
if h : j = i then eq.rec_on h b else 0 :=
dfinsupp.single_apply
omit dec_ι
section congr_left
variables {κ : Type*}
/--Reindexing terms of a direct sum is linear.-/
def lequiv_congr_left (h : ι ≃ κ) : (⨁ i, M i) ≃ₗ[R] ⨁ k, M (h.symm k) :=
{ map_smul' := dfinsupp.comap_domain'_smul _ _,
..equiv_congr_left h }
@[simp] lemma lequiv_congr_left_apply (h : ι ≃ κ) (f : ⨁ i, M i) (k : κ) :
lequiv_congr_left R h f k = f (h.symm k) := equiv_congr_left_apply _ _ _
end congr_left
section sigma
variables {α : ι → Type*} {δ : Π i, α i → Type w}
variables [Π i j, add_comm_monoid (δ i j)] [Π i j, module R (δ i j)]
/--`curry` as a linear map.-/
noncomputable def sigma_lcurry : (⨁ (i : Σ i, _), δ i.1 i.2) →ₗ[R] ⨁ i j, δ i j :=
{ map_smul' := λ r, by convert (@dfinsupp.sigma_curry_smul _ _ _ δ _ _ _ r),
..sigma_curry }
@[simp] lemma sigma_lcurry_apply (f : ⨁ (i : Σ i, _), δ i.1 i.2) (i : ι) (j : α i) :
sigma_lcurry R f i j = f ⟨i, j⟩ := sigma_curry_apply f i j
/--`uncurry` as a linear map.-/
noncomputable def sigma_luncurry : (⨁ i j, δ i j) →ₗ[R] ⨁ (i : Σ i, _), δ i.1 i.2 :=
{ map_smul' := dfinsupp.sigma_uncurry_smul,
..sigma_uncurry }
@[simp] lemma sigma_luncurry_apply (f : ⨁ i j, δ i j) (i : ι) (j : α i) :
sigma_luncurry R f ⟨i, j⟩ = f i j := sigma_uncurry_apply f i j
/--`curry_equiv` as a linear equiv.-/
noncomputable def sigma_lcurry_equiv : (⨁ (i : Σ i, _), δ i.1 i.2) ≃ₗ[R] ⨁ i j, δ i j :=
{ ..sigma_curry_equiv, ..sigma_lcurry R }
end sigma
section option
variables {α : option ι → Type w} [Π i, add_comm_monoid (α i)] [Π i, module R (α i)]
include dec_ι
/--Linear isomorphism obtained by separating the term of index `none` of a direct sum over
`option ι`.-/
@[simps] noncomputable def lequiv_prod_direct_sum : (⨁ i, α i) ≃ₗ[R] α none × ⨁ i, α (some i) :=
{ map_smul' := dfinsupp.equiv_prod_dfinsupp_smul,
..add_equiv_prod_direct_sum }
end option
end general
section submodule
section semiring
variables {R : Type u} [semiring R]
variables {ι : Type v} [dec_ι : decidable_eq ι]
include dec_ι
variables {M : Type*} [add_comm_monoid M] [module R M]
variables (A : ι → submodule R M)
/-- The canonical embedding from `⨁ i, A i` to `M` where `A` is a collection of `submodule R M`
indexed by `ι`. This is `direct_sum.coe_add_monoid_hom` as a `linear_map`. -/
def coe_linear_map : (⨁ i, A i) →ₗ[R] M := to_module R ι M (λ i, (A i).subtype)
@[simp] lemma coe_linear_map_of (i : ι) (x : A i) :
direct_sum.coe_linear_map A (of (λ i, A i) i x) = x :=
to_add_monoid_of _ _ _
variables {A}
/-- If a direct sum of submodules is internal then the submodules span the module. -/
lemma is_internal.submodule_supr_eq_top (h : is_internal A) : supr A = ⊤ :=
begin
rw [submodule.supr_eq_range_dfinsupp_lsum, linear_map.range_eq_top],
exact function.bijective.surjective h,
end
/-- If a direct sum of submodules is internal then the submodules are independent. -/
lemma is_internal.submodule_independent (h : is_internal A) :
complete_lattice.independent A :=
complete_lattice.independent_of_dfinsupp_lsum_injective _ h.injective
/-- Given an internal direct sum decomposition of a module `M`, and a basis for each of the
components of the direct sum, the disjoint union of these bases is a basis for `M`. -/
noncomputable def is_internal.collected_basis
(h : is_internal A) {α : ι → Type*} (v : Π i, basis (α i) R (A i)) :
basis (Σ i, α i) R M :=
{ repr :=
(linear_equiv.of_bijective (direct_sum.coe_linear_map A) h).symm ≪≫ₗ
(dfinsupp.map_range.linear_equiv (λ i, (v i).repr)) ≪≫ₗ
(sigma_finsupp_lequiv_dfinsupp R).symm }
@[simp] lemma is_internal.collected_basis_coe
(h : is_internal A) {α : ι → Type*} (v : Π i, basis (α i) R (A i)) :
⇑(h.collected_basis v) = λ a : Σ i, (α i), ↑(v a.1 a.2) :=
begin
funext a,
simp only [is_internal.collected_basis, to_module, coe_linear_map,
add_equiv.to_fun_eq_coe, basis.coe_of_repr, basis.repr_symm_apply, dfinsupp.lsum_apply_apply,
dfinsupp.map_range.linear_equiv_apply, dfinsupp.map_range.linear_equiv_symm,
dfinsupp.map_range_single, finsupp.total_single, linear_equiv.of_bijective_apply,
linear_equiv.symm_symm, linear_equiv.symm_trans_apply, one_smul,
sigma_finsupp_add_equiv_dfinsupp_apply, sigma_finsupp_equiv_dfinsupp_single,
sigma_finsupp_lequiv_dfinsupp_apply],
convert dfinsupp.sum_add_hom_single (λ i, (A i).subtype.to_add_monoid_hom) a.1 (v a.1 a.2),
end
lemma is_internal.collected_basis_mem
(h : is_internal A) {α : ι → Type*} (v : Π i, basis (α i) R (A i)) (a : Σ i, α i) :
h.collected_basis v a ∈ A a.1 :=
by simp
/-- When indexed by only two distinct elements, `direct_sum.is_internal` implies
the two submodules are complementary. Over a `ring R`, this is true as an iff, as
`direct_sum.is_internal_iff_is_compl`. -/
lemma is_internal.is_compl {A : ι → submodule R M} {i j : ι} (hij : i ≠ j)
(h : (set.univ : set ι) = {i, j}) (hi : is_internal A) : is_compl (A i) (A j) :=
⟨hi.submodule_independent.pairwise_disjoint hij,
codisjoint_iff.mpr $ eq.symm $ hi.submodule_supr_eq_top.symm.trans $
by rw [←Sup_pair, supr, ←set.image_univ, h, set.image_insert_eq, set.image_singleton]⟩
end semiring
section ring
variables {R : Type u} [ring R]
variables {ι : Type v} [dec_ι : decidable_eq ι]
include dec_ι
variables {M : Type*} [add_comm_group M] [module R M]
/-- Note that this is not generally true for `[semiring R]`; see
`complete_lattice.independent.dfinsupp_lsum_injective` for details. -/
lemma is_internal_submodule_of_independent_of_supr_eq_top {A : ι → submodule R M}
(hi : complete_lattice.independent A) (hs : supr A = ⊤) : is_internal A :=
⟨hi.dfinsupp_lsum_injective, linear_map.range_eq_top.1 $
(submodule.supr_eq_range_dfinsupp_lsum _).symm.trans hs⟩
/-- `iff` version of `direct_sum.is_internal_submodule_of_independent_of_supr_eq_top`,
`direct_sum.is_internal.independent`, and `direct_sum.is_internal.supr_eq_top`.
-/
lemma is_internal_submodule_iff_independent_and_supr_eq_top (A : ι → submodule R M) :
is_internal A ↔ complete_lattice.independent A ∧ supr A = ⊤ :=
⟨λ i, ⟨i.submodule_independent, i.submodule_supr_eq_top⟩,
and.rec is_internal_submodule_of_independent_of_supr_eq_top⟩
/-- If a collection of submodules has just two indices, `i` and `j`, then
`direct_sum.is_internal` is equivalent to `is_compl`. -/
lemma is_internal_submodule_iff_is_compl (A : ι → submodule R M) {i j : ι} (hij : i ≠ j)
(h : (set.univ : set ι) = {i, j}) :
is_internal A ↔ is_compl (A i) (A j) :=
begin
have : ∀ k, k = i ∨ k = j := λ k, by simpa using set.ext_iff.mp h k,
rw [is_internal_submodule_iff_independent_and_supr_eq_top,
supr, ←set.image_univ, h, set.image_insert_eq, set.image_singleton, Sup_pair,
complete_lattice.independent_pair hij this],
exact ⟨λ ⟨hd, ht⟩, ⟨hd, codisjoint_iff.mpr ht⟩, λ ⟨hd, ht⟩, ⟨hd, ht.eq_top⟩⟩,
end
/-! Now copy the lemmas for subgroup and submonoids. -/
lemma is_internal.add_submonoid_independent {M : Type*} [add_comm_monoid M]
{A : ι → add_submonoid M} (h : is_internal A) :
complete_lattice.independent A :=
complete_lattice.independent_of_dfinsupp_sum_add_hom_injective _ h.injective
lemma is_internal.add_subgroup_independent {M : Type*} [add_comm_group M]
{A : ι → add_subgroup M} (h : is_internal A) :
complete_lattice.independent A :=
complete_lattice.independent_of_dfinsupp_sum_add_hom_injective' _ h.injective
end ring
end submodule
end direct_sum
|
75b9ba6b5b4779824f894dde2f869fc937bfe2a7 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/algebra/module/submodule/bilinear.lean | 7d877ca6eec7614606a887fd523cdd998b28d454 | [
"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 | 6,017 | lean | /-
Copyright (c) 2019 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau, Eric Wieser
-/
import linear_algebra.span
import linear_algebra.bilinear_map
/-!
# Images of pairs of submodules under bilinear maps
This file provides `submodule.map₂`, which is later used to implement `submodule.has_mul`.
## Main results
* `submodule.map₂_eq_span_image2`: the image of two submodules under a bilinear map is the span of
their `set.image2`.
## Notes
This file is quite similar to the n-ary section of `data.set.basic` and to `order.filter.n_ary`.
Please keep them in sync.
-/
universes uι u v
open set
open_locale big_operators
open_locale pointwise
namespace submodule
variables {ι : Sort uι} {R M N P : Type*}
variables [comm_semiring R] [add_comm_monoid M] [add_comm_monoid N] [add_comm_monoid P]
variables [module R M] [module R N] [module R P]
/-- Map a pair of submodules under a bilinear map.
This is the submodule version of `set.image2`. -/
def map₂ (f : M →ₗ[R] N →ₗ[R] P) (p : submodule R M) (q : submodule R N) : submodule R P :=
⨆ s : p, q.map $ f s
theorem apply_mem_map₂ (f : M →ₗ[R] N →ₗ[R] P) {m : M} {n : N}
{p : submodule R M} {q : submodule R N} (hm : m ∈ p) (hn : n ∈ q) : f m n ∈ map₂ f p q :=
(le_supr _ ⟨m, hm⟩ : _ ≤ map₂ f p q) ⟨n, hn, rfl⟩
theorem map₂_le {f : M →ₗ[R] N →ₗ[R] P}
{p : submodule R M} {q : submodule R N} {r : submodule R P} :
map₂ f p q ≤ r ↔ ∀ (m ∈ p) (n ∈ q), f m n ∈ r :=
⟨λ H m hm n hn, H $ apply_mem_map₂ _ hm hn,
λ H, supr_le $ λ ⟨m, hm⟩, map_le_iff_le_comap.2 $ λ n hn, H m hm n hn⟩
variables R
theorem map₂_span_span (f : M →ₗ[R] N →ₗ[R] P) (s : set M) (t : set N) :
map₂ f (span R s) (span R t) = span R (set.image2 (λ m n, f m n) s t) :=
begin
apply le_antisymm,
{ rw map₂_le, intros a ha b hb,
apply span_induction ha,
work_on_goal 1 { intros, apply span_induction hb,
work_on_goal 1 { intros, exact subset_span ⟨_, _, ‹_›, ‹_›, rfl⟩ } },
all_goals {
intros,
simp only [linear_map.map_zero, linear_map.zero_apply, zero_mem,
linear_map.map_add, linear_map.add_apply, linear_map.map_smul, linear_map.smul_apply] },
all_goals {
solve_by_elim [add_mem _ _, zero_mem _, smul_mem _ _ _]
{ max_depth := 4, discharger := tactic.interactive.apply_instance } } },
{ rw span_le, rintros _ ⟨a, b, ha, hb, rfl⟩,
exact apply_mem_map₂ _ (subset_span ha) (subset_span hb) }
end
variables {R}
@[simp] theorem map₂_bot_right (f : M →ₗ[R] N →ₗ[R] P) (p : submodule R M) : map₂ f p ⊥ = ⊥ :=
eq_bot_iff.2 $ map₂_le.2 $ λ m hm n hn,
by { rw [submodule.mem_bot] at hn ⊢, rw [hn, linear_map.map_zero] }
@[simp] theorem map₂_bot_left (f : M →ₗ[R] N →ₗ[R] P) (q : submodule R N) : map₂ f ⊥ q = ⊥ :=
eq_bot_iff.2 $ map₂_le.2 $ λ m hm n hn,
by { rw [submodule.mem_bot] at hm ⊢, rw [hm, linear_map.map_zero₂] }
@[mono] theorem map₂_le_map₂ {f : M →ₗ[R] N →ₗ[R] P}
{p₁ p₂ : submodule R M} {q₁ q₂ : submodule R N} (hp : p₁ ≤ p₂) (hq : q₁ ≤ q₂) :
map₂ f p₁ q₁ ≤ map₂ f p₂ q₂ :=
map₂_le.2 $ λ m hm n hn, apply_mem_map₂ _ (hp hm) (hq hn)
theorem map₂_le_map₂_left {f : M →ₗ[R] N →ₗ[R] P}
{p₁ p₂ : submodule R M} {q : submodule R N} (h : p₁ ≤ p₂) : map₂ f p₁ q ≤ map₂ f p₂ q :=
map₂_le_map₂ h (le_refl q)
theorem map₂_le_map₂_right {f : M →ₗ[R] N →ₗ[R] P}
{p : submodule R M} {q₁ q₂ : submodule R N} (h : q₁ ≤ q₂): map₂ f p q₁ ≤ map₂ f p q₂ :=
map₂_le_map₂ (le_refl p) h
theorem map₂_sup_right (f : M →ₗ[R] N →ₗ[R] P) (p : submodule R M) (q₁ q₂ : submodule R N) :
map₂ f p (q₁ ⊔ q₂) = map₂ f p q₁ ⊔ map₂ f p q₂ :=
le_antisymm (map₂_le.2 $ λ m hm np hnp, let ⟨n, hn, p, hp, hnp⟩ := mem_sup.1 hnp in
mem_sup.2 ⟨_, apply_mem_map₂ _ hm hn, _, apply_mem_map₂ _ hm hp, hnp ▸ (map_add _ _ _).symm⟩)
(sup_le (map₂_le_map₂_right le_sup_left) (map₂_le_map₂_right le_sup_right))
theorem map₂_sup_left (f : M →ₗ[R] N →ₗ[R] P) (p₁ p₂ : submodule R M) (q : submodule R N) :
map₂ f (p₁ ⊔ p₂) q = map₂ f p₁ q ⊔ map₂ f p₂ q :=
le_antisymm (map₂_le.2 $ λ mn hmn p hp, let ⟨m, hm, n, hn, hmn⟩ := mem_sup.1 hmn in
mem_sup.2 ⟨_, apply_mem_map₂ _ hm hp, _, apply_mem_map₂ _ hn hp,
hmn ▸ (linear_map.map_add₂ _ _ _ _).symm⟩)
(sup_le (map₂_le_map₂_left le_sup_left) (map₂_le_map₂_left le_sup_right))
lemma image2_subset_map₂ (f : M →ₗ[R] N →ₗ[R] P) (p : submodule R M) (q : submodule R N) :
set.image2 (λ m n, f m n) (↑p : set M) (↑q : set N) ⊆ (↑(map₂ f p q) : set P) :=
by { rintros _ ⟨i, j, hi, hj, rfl⟩, exact apply_mem_map₂ _ hi hj }
lemma map₂_eq_span_image2 (f : M →ₗ[R] N →ₗ[R] P) (p : submodule R M) (q : submodule R N) :
map₂ f p q = span R (set.image2 (λ m n, f m n) (p : set M) (q : set N)) :=
by rw [← map₂_span_span, span_eq, span_eq]
lemma map₂_supr_left (f : M →ₗ[R] N →ₗ[R] P) (s : ι → submodule R M) (t : submodule R N) :
map₂ f (⨆ i, s i) t = ⨆ i, map₂ f (s i) t :=
begin
suffices :
map₂ f (⨆ i, span R (s i : set M)) (span R t) = (⨆ i, map₂ f (span R (s i)) (span R t)),
{ simpa only [span_eq] using this },
simp_rw [map₂_span_span, ← span_Union, map₂_span_span, set.image2_Union_left],
end
lemma map₂_supr_right (f : M →ₗ[R] N →ₗ[R] P) (s : submodule R M) (t : ι → submodule R N) :
map₂ f s (⨆ i, t i) = ⨆ i, map₂ f s (t i) :=
begin
suffices :
map₂ f (span R s) (⨆ i, span R (t i : set N)) = (⨆ i, map₂ f (span R s) (span R (t i))),
{ simpa only [span_eq] using this },
simp_rw [map₂_span_span, ← span_Union, map₂_span_span, set.image2_Union_right],
end
end submodule
|
1cb07ce2d6d3ea621135c4534dd36adf6627cf0f | 6094e25ea0b7699e642463b48e51b2ead6ddc23f | /library/data/set/classical_inverse.lean | c12e8498e727cc4e6e4eb1aaba672cf17017981a | [
"Apache-2.0"
] | permissive | gbaz/lean | a7835c4e3006fbbb079e8f8ffe18aacc45adebfb | a501c308be3acaa50a2c0610ce2e0d71becf8032 | refs/heads/master | 1,611,198,791,433 | 1,451,339,111,000 | 1,451,339,111,000 | 48,713,797 | 0 | 0 | null | 1,451,338,939,000 | 1,451,338,939,000 | null | UTF-8 | Lean | false | false | 2,762 | lean | /-
Copyright (c) 2014 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Jeremy Avigad, Andrew Zipperer
Using classical logic, defines an inverse function.
-/
import .function .map
open eq.ops classical
namespace set
variables {X Y : Type}
noncomputable definition inv_fun (f : X → Y) (a : set X) (dflt : X) (y : Y) : X :=
if H : ∃₀ x ∈ a, f x = y then some H else dflt
theorem inv_fun_pos {f : X → Y} {a : set X} {dflt : X} {y : Y}
(H : ∃₀ x ∈ a, f x = y) : (inv_fun f a dflt y ∈ a) ∧ (f (inv_fun f a dflt y) = y) :=
have H1 : inv_fun f a dflt y = some H, from dif_pos H,
H1⁻¹ ▸ some_spec H
theorem inv_fun_neg {f : X → Y} {a : set X} {dflt : X} {y : Y}
(H : ¬ ∃₀ x ∈ a, f x = y) : inv_fun f a dflt y = dflt :=
dif_neg H
variables {f : X → Y} {a : set X} {b : set Y}
theorem maps_to_inv_fun {dflt : X} (dflta : dflt ∈ a) :
maps_to (inv_fun f a dflt) b a :=
let f' := inv_fun f a dflt in
take y,
assume yb : y ∈ b,
show f' y ∈ a, from
by_cases
(assume H : ∃₀ x ∈ a, f x = y,
and.left (inv_fun_pos H))
(assume H : ¬ ∃₀ x ∈ a, f x = y,
(inv_fun_neg H)⁻¹ ▸ dflta)
theorem left_inv_on_inv_fun_of_inj_on (dflt : X) (H : inj_on f a) :
left_inv_on (inv_fun f a dflt) f a :=
let f' := inv_fun f a dflt in
take x,
assume xa : x ∈ a,
have H1 : ∃₀ x' ∈ a, f x' = f x, from exists.intro x (and.intro xa rfl),
have H2 : f' (f x) ∈ a ∧ f (f' (f x)) = f x, from inv_fun_pos H1,
show f' (f x) = x, from H (and.left H2) xa (and.right H2)
theorem right_inv_on_inv_fun_of_surj_on (dflt : X) (H : surj_on f a b) :
right_inv_on (inv_fun f a dflt) f b :=
let f' := inv_fun f a dflt in
take y,
assume yb: y ∈ b,
obtain x (Hx : x ∈ a ∧ f x = y), from H yb,
have Hy : f' y ∈ a ∧ f (f' y) = y, from inv_fun_pos (exists.intro x Hx),
and.right Hy
end set
open set
namespace map
variables {X Y : Type} {a : set X} {b : set Y}
protected noncomputable definition inverse (f : map a b) {dflt : X} (dflta : dflt ∈ a) :=
map.mk (inv_fun f a dflt) (@maps_to_inv_fun _ _ _ _ b _ dflta)
theorem left_inverse_inverse {f : map a b} {dflt : X} (dflta : dflt ∈ a) (H : map.injective f) :
map.left_inverse (map.inverse f dflta) f :=
left_inv_on_inv_fun_of_inj_on dflt H
theorem right_inverse_inverse {f : map a b} {dflt : X} (dflta : dflt ∈ a) (H : map.surjective f) :
map.right_inverse (map.inverse f dflta) f :=
right_inv_on_inv_fun_of_surj_on dflt H
theorem is_inverse_inverse {f : map a b} {dflt : X} (dflta : dflt ∈ a) (H : map.bijective f) :
map.is_inverse (map.inverse f dflta) f :=
and.intro
(left_inverse_inverse dflta (and.left H))
(right_inverse_inverse dflta (and.right H))
end map
|
becc7fd30c47d4293f50d19858ddb9904bc41065 | 5d166a16ae129621cb54ca9dde86c275d7d2b483 | /tests/lean/run/interactive1.lean | 3fa121f57ab3655b0a6f6f92110249be3a2fc447 | [
"Apache-2.0"
] | permissive | jcarlson23/lean | b00098763291397e0ac76b37a2dd96bc013bd247 | 8de88701247f54d325edd46c0eed57aeacb64baf | refs/heads/master | 1,611,571,813,719 | 1,497,020,963,000 | 1,497,021,515,000 | 93,882,536 | 1 | 0 | null | 1,497,029,896,000 | 1,497,029,896,000 | null | UTF-8 | Lean | false | false | 912 | lean | def f : nat → nat := λ a, a
@[simp] lemma f_def (a : nat) : f a = a :=
rfl
def g : nat → nat := λ a, 1 + a
lemma g_def (a : nat) : g a = 1 + a :=
rfl
example (a b c : nat) : b = 0 → c = 1 → a + b + f c = g (f a) :=
begin
intros h1 h2,
simp [h1, h2, g_def, nat.add_comm 1 a]
end
example (b c : nat) : b = 0 → c = b + 1 → c = 1 :=
begin
intros h1 h2,
simp [h1] at h2,
assumption
end
open nat
example (b c : nat) : succ b = succ c → b + 2 = c + 2 :=
begin
intro h,
injection h with h', clear h,
trace_state,
subst h'
end
constant h : nat → nat → nat
axiom bla : ∀ a b : nat, h a b = h b a
axiom boo : ∀ a : nat, h 0 a = a
attribute [simp] boo bla
example (a b : nat) : a = b → h 0 a = b :=
begin
intro h,
simp [h] without bla -- should fail if bla is used
end
open tactic
example (a b : nat) : a = b → h 0 a = b :=
by simp without bla {contextual := tt}
|
08cb0c8c4e1565471edc7871e15eb66154539ae7 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/algebra/iterate_hom_auto.lean | a01f88480d33b2af66edd6886bf7cd0a9111ad3b | [] | no_license | AurelienSaue/Mathlib4_auto | f538cfd0980f65a6361eadea39e6fc639e9dae14 | 590df64109b08190abe22358fabc3eae000943f2 | refs/heads/master | 1,683,906,849,776 | 1,622,564,669,000 | 1,622,564,669,000 | 371,723,747 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 5,647 | lean | /-
Copyright (c) 2020 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Yury Kudryashov
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.algebra.group_power.default
import Mathlib.logic.function.iterate
import Mathlib.PostPort
universes u_1 u_3 u_5
namespace Mathlib
/-!
# Iterates of monoid and ring homomorphisms
Iterate of a monoid/ring homomorphism is a monoid/ring homomorphism but it has a wrong type, so Lean
can't apply lemmas like `monoid_hom.map_one` to `f^[n] 1`. Though it is possible to define
a monoid structure on the endomorphisms, quite often we do not want to convert from
`M →* M` to (not yet defined) `monoid.End M` and from `f^[n]` to `f^n` just to apply a simple lemma.
So, we restate standard `*_hom.map_*` lemmas under names `*_hom.iterate_map_*`.
We also prove formulas for iterates of add/mul left/right.
## Tags
homomorphism, iterate
-/
namespace monoid_hom
@[simp] theorem Mathlib.add_monoid_hom.iterate_map_zero {M : Type u_1} [add_monoid M] (f : M →+ M)
(n : ℕ) : nat.iterate (⇑f) n 0 = 0 :=
function.iterate_fixed (add_monoid_hom.map_zero f) n
@[simp] theorem iterate_map_mul {M : Type u_1} [monoid M] (f : M →* M) (n : ℕ) (x : M) (y : M) :
nat.iterate (⇑f) n (x * y) = nat.iterate (⇑f) n x * nat.iterate (⇑f) n y :=
function.semiconj₂.iterate (map_mul f) n x y
@[simp] theorem iterate_map_inv {G : Type u_3} [group G] (f : G →* G) (n : ℕ) (x : G) :
nat.iterate (⇑f) n (x⁻¹) = (nat.iterate (⇑f) n x⁻¹) :=
function.commute.iterate_left (map_inv f) n x
theorem iterate_map_pow {M : Type u_1} [monoid M] (f : M →* M) (a : M) (n : ℕ) (m : ℕ) :
nat.iterate (⇑f) n (a ^ m) = nat.iterate (⇑f) n a ^ m :=
function.commute.iterate_left (fun (x : M) => map_pow f x m) n a
theorem iterate_map_gpow {G : Type u_3} [group G] (f : G →* G) (a : G) (n : ℕ) (m : ℤ) :
nat.iterate (⇑f) n (a ^ m) = nat.iterate (⇑f) n a ^ m :=
function.commute.iterate_left (fun (x : G) => map_gpow f x m) n a
end monoid_hom
namespace add_monoid_hom
@[simp] theorem iterate_map_sub {G : Type u_3} [add_group G] (f : G →+ G) (n : ℕ) (x : G) (y : G) :
nat.iterate (⇑f) n (x - y) = nat.iterate (⇑f) n x - nat.iterate (⇑f) n y :=
function.semiconj₂.iterate (map_sub f) n x y
theorem iterate_map_smul {M : Type u_1} [add_monoid M] (f : M →+ M) (n : ℕ) (m : ℕ) (x : M) :
nat.iterate (⇑f) n (m •ℕ x) = m •ℕ nat.iterate (⇑f) n x :=
monoid_hom.iterate_map_pow (coe_fn to_multiplicative f) x n m
theorem iterate_map_gsmul {G : Type u_3} [add_group G] (f : G →+ G) (n : ℕ) (m : ℤ) (x : G) :
nat.iterate (⇑f) n (m •ℤ x) = m •ℤ nat.iterate (⇑f) n x :=
monoid_hom.iterate_map_gpow (coe_fn to_multiplicative f) x n m
end add_monoid_hom
namespace ring_hom
theorem coe_pow {R : Type u_5} [semiring R] (f : R →+* R) (n : ℕ) : ⇑(f ^ n) = nat.iterate (⇑f) n :=
sorry
theorem iterate_map_one {R : Type u_5} [semiring R] (f : R →+* R) (n : ℕ) :
nat.iterate (⇑f) n 1 = 1 :=
monoid_hom.iterate_map_one (to_monoid_hom f) n
theorem iterate_map_zero {R : Type u_5} [semiring R] (f : R →+* R) (n : ℕ) :
nat.iterate (⇑f) n 0 = 0 :=
add_monoid_hom.iterate_map_zero (to_add_monoid_hom f) n
theorem iterate_map_add {R : Type u_5} [semiring R] (f : R →+* R) (n : ℕ) (x : R) (y : R) :
nat.iterate (⇑f) n (x + y) = nat.iterate (⇑f) n x + nat.iterate (⇑f) n y :=
add_monoid_hom.iterate_map_add (to_add_monoid_hom f) n x y
theorem iterate_map_mul {R : Type u_5} [semiring R] (f : R →+* R) (n : ℕ) (x : R) (y : R) :
nat.iterate (⇑f) n (x * y) = nat.iterate (⇑f) n x * nat.iterate (⇑f) n y :=
monoid_hom.iterate_map_mul (to_monoid_hom f) n x y
theorem iterate_map_pow {R : Type u_5} [semiring R] (f : R →+* R) (a : R) (n : ℕ) (m : ℕ) :
nat.iterate (⇑f) n (a ^ m) = nat.iterate (⇑f) n a ^ m :=
monoid_hom.iterate_map_pow (to_monoid_hom f) a n m
theorem iterate_map_smul {R : Type u_5} [semiring R] (f : R →+* R) (n : ℕ) (m : ℕ) (x : R) :
nat.iterate (⇑f) n (m •ℕ x) = m •ℕ nat.iterate (⇑f) n x :=
add_monoid_hom.iterate_map_smul (to_add_monoid_hom f) n m x
theorem iterate_map_sub {R : Type u_5} [ring R] (f : R →+* R) (n : ℕ) (x : R) (y : R) :
nat.iterate (⇑f) n (x - y) = nat.iterate (⇑f) n x - nat.iterate (⇑f) n y :=
add_monoid_hom.iterate_map_sub (to_add_monoid_hom f) n x y
theorem iterate_map_neg {R : Type u_5} [ring R] (f : R →+* R) (n : ℕ) (x : R) :
nat.iterate (⇑f) n (-x) = -nat.iterate (⇑f) n x :=
add_monoid_hom.iterate_map_neg (to_add_monoid_hom f) n x
theorem iterate_map_gsmul {R : Type u_5} [ring R] (f : R →+* R) (n : ℕ) (m : ℤ) (x : R) :
nat.iterate (⇑f) n (m •ℤ x) = m •ℤ nat.iterate (⇑f) n x :=
add_monoid_hom.iterate_map_gsmul (to_add_monoid_hom f) n m x
end ring_hom
@[simp] theorem mul_left_iterate {M : Type u_1} [monoid M] (a : M) (n : ℕ) :
nat.iterate (Mul.mul a) n = Mul.mul (a ^ n) :=
sorry
@[simp] theorem add_left_iterate {M : Type u_1} [add_monoid M] (a : M) (n : ℕ) :
nat.iterate (Add.add a) n = Add.add (n •ℕ a) :=
mul_left_iterate a n
@[simp] theorem mul_right_iterate {M : Type u_1} [monoid M] (a : M) (n : ℕ) :
nat.iterate (fun (x : M) => x * a) n = fun (x : M) => x * a ^ n :=
sorry
@[simp] theorem add_right_iterate {M : Type u_1} [add_monoid M] (a : M) (n : ℕ) :
nat.iterate (fun (x : M) => x + a) n = fun (x : M) => x + n •ℕ a :=
mul_right_iterate a n
end Mathlib |
9cd23181645565795e0292a017cf04de3a3c8500 | ecdf4e083eb363cd3a0d6880399f86e2cd7f5adb | /src/group_theory/sporadic_group.lean | cb7347ffddfb694e3aaa61fe71691391e6251eb4 | [] | no_license | fpvandoorn/formalabstracts | 29aa71772da418f18994c38379e2192a6ef361f7 | cea2f9f96d89ee1187d1b01e33f22305cdfe4d59 | refs/heads/master | 1,609,476,761,601 | 1,558,130,287,000 | 1,558,130,287,000 | 97,261,457 | 0 | 2 | null | 1,550,879,230,000 | 1,500,056,313,000 | Lean | UTF-8 | Lean | false | false | 14,717 | lean | import .basic .monster .presentation .suzuki .higman_sims .mclaughlin .conway_groups .mathieu_group
-- import tactic.metadata
noncomputable theory
open monster suzuki higman_sims mclaughlin conway_groups mathieu_group coxeter_vertices mul_action
open category_theory (mk_ob)
local infix ` ≅ `:60 := isomorphic
local notation `⟪`:50 a `⟫`:50 := free_group.of a
local notation h :: t := dvector.cons h t
local notation `[` l:(foldr `, ` (h t, dvector.cons h t) dvector.nil `]`) := l
local infix ` ↑↑ `:65 := right_conjugation
/- the first happy family, a.k.a. Mathieu groups -/
/-- The group $M_{11}$ is the stabilizer of an arbitrary point of the steiner system $S(5,6,12)$
under the evaluation action of its Automorphism group.-/
@[fabstract]
def M11 : Group :=
mk_ob $ @stabilizer _ _ _ (mathieu_group.evaluation_action s_5_6_12)
(classical.choice $ nonempty_steiner_system dec_trivial)
/--The group $M_{12}$ is the automorphism group of the steiner system $S(5,6,12)$.-/
@[fabstract]
def M12 : Group := mk_ob $ Aut(s_5_6_12)
/-- The group $M_{22}$ is the stabilizer of two arbitrary points of the steiner system $S(5,8,24)$
under the evaluation action of its automorphism group. -/
@[fabstract]
def M22 : Group :=
have H : ∃x : s_5_8_24 × s_5_8_24, x.1 ≠ x.2, from omitted,
mk_ob $ two_pt_stabilizer (mathieu_group.evaluation_action s_5_8_24) (classical.some_spec H)
/-- The group $M_{23}$ is the stabilizer of an arbitrary point of the steiner system $S(5,8,24)$
under the evaluation action of its automorphism group.-/
@[fabstract]
def M23 : Group :=
mk_ob $ @stabilizer _ _ _ (mathieu_group.evaluation_action s_5_8_24)
(classical.choice $ nonempty_steiner_system dec_trivial)
/-- The group $M_{24}$ is the automorphism group of the steiner system $S(5,8,24)$. -/
@[fabstract]
def M24 : Group := mk_ob $ Aut(s_5_8_24)
/- the second happy family -/
/-- the Conway group Co₁ -/
@[fabstract]
def Co1 : Group := Co1
/-- the Conway group Co₂ -/
@[fabstract]
def Co2 : Group := Co2
/-- the Conway group Co₃ -/
@[fabstract]
def Co3 : Group := Co3
/-- the McLaughlin group -/
@[fabstract]
def McL : Group := McL
/-- the Higman–Sims group -/
@[fabstract]
def HS : Group := HS
namespace J2
def a : free_group $ dfin 4 := ⟪(by to_dfin 0)⟫
def b : free_group $ dfin 4 := ⟪(by to_dfin 1)⟫
def u : free_group $ dfin 4 := ⟪(by to_dfin 2)⟫
def v : free_group $ dfin 4 := ⟪(by to_dfin 3)⟫
end J2
section J2
open J2
/-- the Hall-Janko group J₂ -/
/- From the corresponding entry in the atlas of finite groups -/
@[fabstract]
def J2 : Group :=
⟪dfin 4 | {a * b * u ⁻¹, a * b⁻¹ * v ⁻¹, a^2, b^3, u^15,
(u^4 * v^2 * u^3 * v^3)^2, (u^3 * v * (u^2 * v^2)^2)^2} ⟫
end J2
/-- the Suzuki sporadic group -/
@[fabstract]
def Suz : Group := Suz
/- THE THIRD HAPPY FAMILY -/
-- todo: move monster here
/-- The baby monster group B is defined as follows:
if x be any element in conjugacy class 2A,
then the centralizer C_M(x) is 2 ⬝ B, so B ≅ C_M(x)/Z(C_M(x)) -/
@[fabstract]
def BabyMonster : Group :=
let C := conj_class Monster 2 'A' in
let x := classical.some C.1.2 in
let Cx : set Monster := centralizer {x} in
mk_ob $ quotient_group.quotient $ is_subgroup.center $ Cx
/-- Fi24 is characterized by 3 ⬝ Fi24 ≅ N_M(x) where x is any element in conjugacy class 3A.
The derived subgroup of this group is the sporadic group Fi24' -/
/- todo: double check that quotienting out the span of x indeed gives Fi24. -/
@[fabstract]
def Fi24 : Group :=
let C := conj_class Monster 3 'A' in
let x := classical.some C.1.2 in
let N_Mx : set Monster := normalizer $ group.closure {x} in
let span_x : set N_Mx := induced_subgroup (group.closure {x}) N_Mx in
by exact mk_ob (quotient_group.quotient span_x)
/-- The Fischer group Fi24' -/
@[fabstract]
def Fi24' : Group :=
mk_ob $ derived_subgroup Fi24
/- A 3-transposition group is a “finite group G generated by a conjugacy class D of involutions, such that any two elements of D have a product of order at most 3, and … such that G’ = G” and any normal 2- or 3-subgroup of G is central. The elements of D are known as 3-transpositions, or just transpositions if there is no risk of confusion” -/
def Y432 : Group := coxeter_group $ matrix_of_graph (coxeter_edges [4,3,2])
namespace Fi23
def a : Y432 := generated_of $ torso
def b₁ : Y432 := generated_of $ arm (by to_dfin 0) (by to_dfin 0)
def c₁ : Y432 := generated_of $ arm (by to_dfin 0) (by to_dfin 1)
def b₂ : Y432 := generated_of $ arm (by to_dfin 1) (by to_dfin 0)
def c₂ : Y432 := generated_of $ arm (by to_dfin 1) (by to_dfin 1)
def b₃ : Y432 := generated_of $ arm (by to_dfin 2) (by to_dfin 0)
def c₃ : Y432 := generated_of $ arm (by to_dfin 2) (by to_dfin 1)
end Fi23
section Fi23
open Fi23
/- We define Fi23 following p 232 of the atlas -/
/-- the Fischer group Fi23 -/
@[fabstract]
def Fi23 : Group :=
category_theory.mk_ob $ quotient_group.quotient $
is_subgroup.center $ (Y432)/⟪{(a*b₁*c₁*a*b₂*c₂*a*b₃*c₃)^10}⟫
end Fi23
/- We define Fi22 following p 162 of the atlas -/
/-- the Fischer group Fi22 -/
def Y332 : Group := coxeter_group $ matrix_of_graph (coxeter_edges [3,3,2])
namespace Fi22
def a : Y332 := generated_of $ arm (by to_dfin 1) (by to_dfin 2)
def b : Y332 := generated_of $ arm (by to_dfin 1) (by to_dfin 1)
def c : Y332 := generated_of $ arm (by to_dfin 1) (by to_dfin 0)
def d : Y332 := generated_of $ torso
def e : Y332 := generated_of $ arm (by to_dfin 0) (by to_dfin 0)
def f : Y332 := generated_of $ arm (by to_dfin 0) (by to_dfin 1)
def g : Y332 := generated_of $ arm (by to_dfin 0) (by to_dfin 2)
def h : Y332 := generated_of $ arm (by to_dfin 2) (by to_dfin 0)
def i : Y332 := generated_of $ arm (by to_dfin 2) (by to_dfin 1)
end Fi22
section Fi22
open Fi22
@[fabstract]
def Fi22 : Group := Y332/⟪{(a*b*c*d*e*f*h)^9, (b*c*d*e*f*g*h)^9, (b*c*d*e*f*d*h*i*d)^10}⟫
end Fi22
/-- the Thompson Group is C_M(x)/<x> for some element x in 3C -/
@[fabstract]
def Th : Group :=
let C := conj_class Monster 3 'C' in
let x := classical.some C.1.2 in
let C_Mx : set Monster := centralizer {x} in
let span_x : set C_Mx := induced_subgroup (group.closure {x}) C_Mx in
by exact mk_ob (quotient_group.quotient span_x)
/-- the Harada–Norton group is C_M(x)/<x> for some element x in 5A -/
@[fabstract]
def HN : Group :=
let C := conj_class Monster 5 'A' in
let x := classical.some C.1.2 in
let C_Mx : set Monster := centralizer {x} in
let span_x : set C_Mx := induced_subgroup (group.closure {x}) C_Mx in
by exact mk_ob (quotient_group.quotient span_x)
/-- the Held group is C_M(x)/<x> for some element x in 7A -/
@[fabstract]
def He : Group :=
let C := conj_class Monster 7 'A' in
let x := classical.some C.1.2 in
let C_Mx : set Monster := centralizer {x} in
let span_x : set C_Mx := induced_subgroup (group.closure {x}) C_Mx in
by exact mk_ob (quotient_group.quotient span_x)
/- the pariahs -/
theorem J1_char : ∃!(G : Group.{0}), ∃(h : fintype G),
by { exactI
simple_group G ∧
(∃(s : set G), is_Sylow_subgroup 2 s ∧ commutative_on s) ∧
(∃x : G, x*x = 1 ∧ mk_ob (centralizer {x} : set G) ≅
mk_ob (cyclic_group 2 × alternating_group 5)) } :=
omitted
/-- the Janko group J₁ -/
@[fabstract]
def J1 : Group := classical.some J1_char
namespace J3
def a := ⟪ff⟫
def b := ⟪tt⟫
end J3
section J3
open J3
/-- the Janko group J₃ -/
/- From http://brauer.maths.qmul.ac.uk/Atlas/v3/pres/J3G1-P1:
Presentation 〈 a, b | a2 = b3 = (ab)19 = [a, b]9 = ((ab)6(ab−1)5)2 = ((ababab−1)2abab−1ab−1abab−1)2 = abab(abab−1)3abab(abab−1)4ab−1(abab−1)3 = (ababababab−1abab−1)4 = 1 〉 -/
@[fabstract]
def J3 : Group :=
⟪bool | {a^2, b^3, (a*b)^19, ⟦a, b⟧^9, ((a*b)^6*(a*b⁻¹)^5)^2,
((a*b*a*b*a*(b⁻¹))^2*a*b*a*b⁻¹*a*b⁻¹*a*b*a*b⁻¹)^2,
a*b*a*b*(a*b*a*b⁻¹)^3*a*b*a*b*(a*b*a*b⁻¹)^4*a*b⁻¹*(a*b*a*b⁻¹)^3,
(a*b*a*b*a*b*a*b*a*b⁻¹*a*b*a*b⁻¹)^4}⟫
end J3
/- Presentation of the Lyons group, following section 3B of the paper
Volker Gebhardt, Two "Short" Presentations for Lyons' Sporadic Simple Group
https://projecteuclid.org/download/pdf_1/euclid.em/1045604668, p 335-6 -/
namespace Ly
def a : free_group $ dfin 5 := ⟪by to_dfin 0⟫
def b : free_group $ dfin 5 := ⟪by to_dfin 1⟫
def c : free_group $ dfin 5 := ⟪by to_dfin 2⟫
def d : free_group $ dfin 5 := ⟪by to_dfin 3⟫
def z : free_group $ dfin 5 := ⟪by to_dfin 4⟫
-- testing binding strength
-- example {α : Type*} [group α] (x y z w : α) : x * y * w ↑↑ z = (x * y * w) ↑↑ z := by refl
-- example {α : Type*} [group α] (x y z w : α) : x ↑↑ z * y * w = x ↑↑ (z * y * w) := by refl
-- example {α : Type*} [group α] (x y z w : α) : x ↑↑ z⁻¹ = x ↑↑ (z⁻¹) := by refl
def RH₃ : set $ free_group $ dfin 5 := {a^8, b^5, (a*b)^4, ⟦a^2,b⟧, ⟦a,b⟧^3}
def RH₂ : set $ free_group $ dfin 5 :=
RH₃ ∪ { c^5, c^3 * (c ↑↑ (a^2))⁻¹,
(c ↑↑ b * a)⁻¹ * (c ↑↑ a^2 * b) * c * b * c * b ⁻¹,
(c ↑↑ b^2)⁻¹ * c^2 * (c ↑↑ b⁻¹) * ((c ↑↑ b)⁻¹)^2 }
def RH₁ : set $ free_group $ dfin 5 :=
{ (a * b⁻¹ * a ↑↑ d)⁻¹ * a * b⁻¹ * a^5,
(b^2 * a ⁻¹ ↑↑ d)⁻¹ * (a⁻¹)^2*b^2 * a⁻¹,
((b*a*c⁻¹*b*a*(b⁻¹)^2*a) ↑↑ d)⁻¹ * c * d, a⁻¹*b*a⁻¹*b⁻¹*a*(b⁻¹)^2*a*c*b⁻¹*c*b*a*c⁻¹,
((a^2*c⁻¹*b*a*c⁻¹*b*a⁻¹*b⁻¹) ↑↑ d*c*d)⁻¹ * (a⁻¹)^2*b⁻¹*a⁻¹*(b⁻¹*c)^2*b^2,
(b^2*a*c*b*a ↑↑ d*c*a⁻¹*b*c*d)⁻¹ * a⁻¹*b*a⁻¹*b⁻¹*a⁻¹*(b⁻¹)^2*c*a⁻¹*b⁻¹*c⁻¹*b*a,
((a * (c⁻¹)^2 *b) ↑↑ d*c*a⁻¹*b*c*d)⁻¹ * (a⁻¹)^4 * b^2 * c⁻¹*b⁻¹*a*b⁻¹*c*a*b⁻¹,
c*a⁻¹*c⁻¹*a*c⁻¹*a⁻¹*c*a*d⁻¹*c⁻¹*a⁻¹*c⁻¹*a*c*a⁻¹*c*d*c*a*c⁻¹*a⁻¹*c⁻¹*a*c*d }
def RG : set $ free_group $ dfin 5 :=
{(a ↑↑ z)⁻¹ * (a⁻¹)^3, (a ↑↑ z * d * z)⁻¹ * a^3,
(c⁻¹ * d⁻¹ * c * b * a * b^2 * (c*b)^2 * c⁻¹ * d ↑↑ z * d * z)⁻¹ * c⁻¹*b*c^2 * a *
c⁻¹*b*d⁻¹*c*a*c⁻¹*b*c⁻¹*(b⁻¹)^2 * c*a⁻¹*c* d⁻¹ * c* b^2 *c*d*a*d⁻¹*c⁻¹*d⁻¹*c*b*a⁻¹*b,
⟦z, d⁻¹*c⁻¹*b*a*b⁻¹*d⁻¹*c*d⁻¹*c⁻¹*d*c⁻¹*b⁻¹*a*b⁻¹*c*d⁻¹*c*d⟧⁻¹ * b * c* b⁻¹*c⁻¹,
(a ↑↑ z*d*b⁻¹*z)⁻¹ * a⁻¹*d⁻¹*c⁻¹*b*(c⁻¹)^2*a*b⁻¹*c*a⁻¹*b^2*c*b⁻¹*c*a⁻¹*c⁻¹*d*b⁻¹*a⁻¹,
(c⁻¹*a⁻¹*d⁻¹*c⁻¹ * b * a * b⁻¹ * a * c⁻¹ *b*c*a*c⁻¹*d⁻¹*c*d*a*c*b⁻¹*a*b*a*c ↑↑ z*d*b⁻¹*z)⁻¹ *
a⁻¹*c*(a⁻¹)^3*c⁻¹*(b⁻¹)^2*c⁻¹*d*c⁻¹*a*c⁻¹*b^2*c*b⁻¹*c*a⁻¹*c⁻¹*d*b⁻¹*c⁻¹*d⁻¹*c⁻¹*b*a*b*d*c*a⁻¹,
((a⁻¹*b*d*c*a⁻¹*b⁻¹*a*b*a⁻¹*c⁻¹*b⁻¹*c*a)↑↑z*d*c*d*z)⁻¹*c⁻¹*a^3*b*c⁻¹*b⁻¹*a⁻¹*c*d⁻¹*c⁻¹*b*a⁻¹*b⁻¹,
(d⁻¹*c*b*a⁻¹*b⁻¹ ↑↑ z*d*c*d*z)⁻¹*a*c*a⁻¹*b*a*c⁻¹*b*c*a*c⁻¹*b⁻¹*a⁻¹*b⁻¹*a*b*d⁻¹*c*a*c⁻¹*b⁻¹*c⁻¹*a,
a*d⁻¹*c⁻¹*b*(a⁻¹)^2*d⁻¹*c⁻¹*(b⁻¹)^2*c⁻¹*d*c⁻¹*(a*c⁻¹)^2 *
b*a⁻¹*c^2*b⁻¹*c*d⁻¹*c*a*c*b⁻¹*a*d⁻¹*z⁻¹*b*z*b⁻¹*z
}
end Ly
section Ly
open Ly
/-We quote: the complete defining set RH₂ ∪ Rh₁ ∪ RG of relations for G with respect
to the generators a,b,c,d and z contains 25 relations of total length 549-/
/-- the Lyons group -/
@[fabstract]
def Ly : Group := ⟪dfin 5 | RH₂ ∪ RH₁ ∪ RG ⟫
end Ly
/- Presentation for the O'Nan group, following the paper
Leonard H. Soicher, A new existence and uniqueness proof for the O'Nan group,
https://doi.org/10.1112/blms/22.2.148 (section 2)-/
/- 8
O'N := ⟨a (torso) --- b --- c --- d --- e --- f, g | relations⟩ -/
namespace O'N
def O'N_diagram :=
annotate (annotated_graph_of_graph $ coxeter_edges [5])
(arm (by to_dfin 0) (by to_dfin 1), arm (by to_dfin 0) (by to_dfin 2)) 8
noncomputable instance O'N_diagram_decidable_rel : decidable_rel $ O'N_diagram.edge :=
λ _ _, classical.prop_decidable _
def O'N_cover := coxeter_group' (matrix_of_annotated_graph O'N_diagram) unit
def a : O'N_cover := generated_of $ sum.inl $ torso
def b : O'N_cover := generated_of $ sum.inl $ arm (by to_dfin 0) (by to_dfin 0)
def c : O'N_cover := generated_of $ sum.inl $ arm (by to_dfin 0) (by to_dfin 1)
def d : O'N_cover := generated_of $ sum.inl $ arm (by to_dfin 0) (by to_dfin 2)
def e : O'N_cover := generated_of $ sum.inl $ arm (by to_dfin 0) (by to_dfin 3)
def f : O'N_cover := generated_of $ sum.inl $ arm (by to_dfin 0) (by to_dfin 4)
def g : O'N_cover := generated_of $ sum.inr $ ()
end O'N
section O'N
open O'N
/-- the O'Nan group -/
@[fabstract]
def O'N : Group :=
O'N_cover/⟪{(a*f)⁻¹ * g^2, ((c*d)^4)⁻¹ * g^2, ⟦c,d*g*d*g⟧,
⟦d, c*g*c*g⟧, (b*c*d*g)^5, f⁻¹ * (d * g)^4,
((b*a)↑↑g)⁻¹ * b * a * ((b*a) ↑↑ c*g*c*g),
((e*f) ↑↑ g)⁻¹ * e * f * ((e*f)↑↑ d*g*d*g)}⟫
end O'N
/-
Atlas entry for J4 presented on its G2-`standard' generators.
G<x,y,t>:=Group<x,y,t| x^2, y^3, (x*y)^23, (x,y)^12, (x,y*x*y)^5,
(x*y*x*y*x*y^-1)^3*(x*y*x*y^-1*x*y^-1)^3, (x*y*(x*y*x*y^-1)^3)^4,
t^2, (t,x), (t,y*x*y*(x*y^-1)^2*(x*y)^3),
(y*t^(y*x*y^-1*x*y*x*y^-1*x))^3,
((y*x*y*x*y*x*y)^3*t*t^((x*y)^3*y*(x*y)^6*y))^2
>;
-/
namespace J4
def x : free_group $ dfin 3 := ⟪(by to_dfin 0)⟫
def y : free_group $ dfin 3 := ⟪(by to_dfin 1)⟫
def t : free_group $ dfin 3 := ⟪(by to_dfin 2)⟫
end J4
section J4
open J4
/-- the Janko group J₄ -/
@[fabstract]
def J4 : Group := ⟪ dfin 3 | {x^2, y^3, (x*y)^23, ⟦x,y⟧^12, ⟦x,y*x*y ⟧^5,
(x*y*x*y*x*y⁻¹)^3*(x*y*x*y⁻¹*x*y⁻¹)^3, (x*y*(x*y*x*y⁻¹)^3)^4,
t^2, ⟦t,x⟧, ⟦t,y*x*y*(x*y⁻¹)^2*(x*y)^3⟧, (y*(t ↑↑ y*x*y⁻¹*x*y*x*y⁻¹*x))^3,
((y*x*y*x*y*x*y)^3 * t * (t ↑↑ (x*y)^3*y*(x*y)^6*y))^2 }⟫
end J4
/- Presentation of the Rudvalis group, following the paper
J.D. Bradley, R.T. Curtis and M. Aslam Malik,
Symmetric generation of the Rudvalis group
https://doi.org/10.1112/jlms/jdq039
Section 4.4 -/
namespace Ru
def u : free_group $ dfin 3 := ⟪(by to_dfin 0)⟫
def v : free_group $ dfin 3 := ⟪(by to_dfin 1)⟫
def t : free_group $ dfin 3 := ⟪(by to_dfin 2)⟫
end Ru
section Ru
open Ru
/-- the Rudvalis group -/
@[fabstract]
def Ru : Group := ⟪dfin 3 | {u^4, v^2, (u*v)^7, (u^2*v)^3, t^2, ⟦t,u↑↑v⟧, ⟦t,v↑↑u⟧,
(u*t)^10, (u*v*u*t)^13, (u*⟦t,u⁻¹⟧*⟦t↑↑u^2, ⟦u⁻¹, t⟧⟧)^3,
((u*t↑↑u*v)*(t*u^2)^4*(t↑↑u*v))^2, (u*(t↑↑v)*⟦t↑↑u*v,u⟧^2)^2}⟫
end Ru
-- run_cmd mk_JSON_dump |
53405cbf70890125e1ad6fcbbf5dc49340acb7da | d48477f6d2a5f434203448f53a910b09488d752b | /src/basic_integral_limits.lean | 1d3e474f9cb374e1469234ab44506b15b4746731 | [] | no_license | ADedecker/gauss | 2576868db8bf338155c8742f17cd06ba72091ee9 | d44d482d49d4755b1d238f3e8a67d22a605970a9 | refs/heads/master | 1,685,610,013,938 | 1,625,525,246,000 | 1,625,525,246,000 | 338,175,066 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 1,429 | lean | import integral_limits
open measure_theory set filter interval_integral
open_locale topological_space
lemma real.integral_exp_Iic (x : ℝ) : ∫ t in Iic x, t.exp = x.exp :=
begin
have key : tendsto (λ (n : ℕ), ∫ (t : ℝ) in -n..x, t.exp) at_top (𝓝 x.exp),
{ have : ∀ (n:ℕ), x.exp - real.exp (-n) = ∫ t:ℝ in -n..x, t.exp,
{ intro n,
rw integral_eq_sub_of_has_deriv_at
(λ t ht, real.has_deriv_at_exp t)
real.continuous_exp.continuous_on },
refine tendsto.congr this _,
convert tendsto_const_nhds.sub
(real.tendsto_exp_neg_at_top_nhds_0.comp tendsto_coe_nat_at_top_at_top),
rw sub_zero _ },
have antimono_neg_coe : ∀ i j : ℕ, i ≤ j → (-j : ℝ) ≤ -i := λ i j hij, by simpa,
have tendsto_neg_coe : tendsto (λ n : ℕ, -(n : ℝ)) at_top at_bot :=
tendsto_neg_at_top_at_bot.comp tendsto_coe_nat_at_top_at_top,
have hfi : integrable_on real.exp (Iic x) :=
integrable_on_Iic_of_tendsto_interval_integral_norm antimono_neg_coe real.measurable_exp
_ _ (λ n, (real.continuous_exp.interval_integrable _ _).1) tendsto_neg_coe
(key.congr $ λ n, integral_congr (λ t _, (real.norm_of_nonneg t.exp_pos.le).symm)),
exact integral_Iic_eq_of_tendsto_interval_integral antimono_neg_coe
real.measurable_exp _ _ hfi tendsto_neg_coe key,
end
example : ∫ (t : ℝ) in Iic 0, t.exp = 1 := real.exp_zero ▸ real.integral_exp_Iic 0 |
724c4bb7f11eabeeb29325de53062ca5099d1822 | 36c7a18fd72e5b57229bd8ba36493daf536a19ce | /hott/types/sigma.hlean | a77beda1833647fc842a601d26ebfcb6d10ed62d | [
"Apache-2.0"
] | permissive | YHVHvx/lean | 732bf0fb7a298cd7fe0f15d82f8e248c11db49e9 | 038369533e0136dd395dc252084d3c1853accbf2 | refs/heads/master | 1,610,701,080,210 | 1,449,128,595,000 | 1,449,128,595,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 18,527 | hlean | /-
Copyright (c) 2014-15 Floris van Doorn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Floris van Doorn
Partially ported from Coq HoTT
Theorems about sigma-types (dependent sums)
-/
import types.prod
open eq sigma sigma.ops equiv is_equiv function is_trunc sum unit
namespace sigma
variables {A A' : Type} {B : A → Type} {B' : A' → Type} {C : Πa, B a → Type}
{D : Πa b, C a b → Type}
{a a' a'' : A} {b b₁ b₂ : B a} {b' : B a'} {b'' : B a''} {u v w : Σa, B a}
definition destruct := @sigma.cases_on
/- Paths in a sigma-type -/
protected definition eta : Π (u : Σa, B a), ⟨u.1 , u.2⟩ = u
| eta ⟨u₁, u₂⟩ := idp
definition eta2 : Π (u : Σa b, C a b), ⟨u.1, u.2.1, u.2.2⟩ = u
| eta2 ⟨u₁, u₂, u₃⟩ := idp
definition eta3 : Π (u : Σa b c, D a b c), ⟨u.1, u.2.1, u.2.2.1, u.2.2.2⟩ = u
| eta3 ⟨u₁, u₂, u₃, u₄⟩ := idp
definition dpair_eq_dpair [unfold 8] (p : a = a') (q : b =[p] b') : ⟨a, b⟩ = ⟨a', b'⟩ :=
apo011 sigma.mk p q
definition sigma_eq [unfold 3 4] (p : u.1 = v.1) (q : u.2 =[p] v.2) : u = v :=
by induction u; induction v; exact (dpair_eq_dpair p q)
definition eq_pr1 [unfold 5] (p : u = v) : u.1 = v.1 :=
ap pr1 p
postfix `..1`:(max+1) := eq_pr1
definition eq_pr2 [unfold 5] (p : u = v) : u.2 =[p..1] v.2 :=
by induction p; exact idpo
postfix `..2`:(max+1) := eq_pr2
definition dpair_sigma_eq (p : u.1 = v.1) (q : u.2 =[p] v.2)
: ⟨(sigma_eq p q)..1, (sigma_eq p q)..2⟩ = ⟨p, q⟩ :=
by induction u; induction v;esimp at *;induction q;esimp
definition sigma_eq_pr1 (p : u.1 = v.1) (q : u.2 =[p] v.2) : (sigma_eq p q)..1 = p :=
(dpair_sigma_eq p q)..1
definition sigma_eq_pr2 (p : u.1 = v.1) (q : u.2 =[p] v.2)
: (sigma_eq p q)..2 =[sigma_eq_pr1 p q] q :=
(dpair_sigma_eq p q)..2
definition sigma_eq_eta (p : u = v) : sigma_eq (p..1) (p..2) = p :=
by induction p; induction u; reflexivity
definition eq2_pr1 {p q : u = v} (r : p = q) : p..1 = q..1 :=
ap eq_pr1 r
definition eq2_pr2 {p q : u = v} (r : p = q) : p..2 =[eq2_pr1 r] q..2 :=
!pathover_ap (apdo eq_pr2 r)
definition tr_pr1_sigma_eq {B' : A → Type} (p : u.1 = v.1) (q : u.2 =[p] v.2)
: transport (λx, B' x.1) (sigma_eq p q) = transport B' p :=
by induction u; induction v; esimp at *;induction q; reflexivity
/- the uncurried version of sigma_eq. We will prove that this is an equivalence -/
definition sigma_eq_unc : Π (pq : Σ(p : u.1 = v.1), u.2 =[p] v.2), u = v
| sigma_eq_unc ⟨pq₁, pq₂⟩ := sigma_eq pq₁ pq₂
definition dpair_sigma_eq_unc : Π (pq : Σ(p : u.1 = v.1), u.2 =[p] v.2),
⟨(sigma_eq_unc pq)..1, (sigma_eq_unc pq)..2⟩ = pq
| dpair_sigma_eq_unc ⟨pq₁, pq₂⟩ := dpair_sigma_eq pq₁ pq₂
definition sigma_eq_pr1_unc (pq : Σ(p : u.1 = v.1), u.2 =[p] v.2)
: (sigma_eq_unc pq)..1 = pq.1 :=
(dpair_sigma_eq_unc pq)..1
definition sigma_eq_pr2_unc (pq : Σ(p : u.1 = v.1), u.2 =[p] v.2) :
(sigma_eq_unc pq)..2 =[sigma_eq_pr1_unc pq] pq.2 :=
(dpair_sigma_eq_unc pq)..2
definition sigma_eq_eta_unc (p : u = v) : sigma_eq_unc ⟨p..1, p..2⟩ = p :=
sigma_eq_eta p
definition tr_sigma_eq_pr1_unc {B' : A → Type}
(pq : Σ(p : u.1 = v.1), u.2 =[p] v.2)
: transport (λx, B' x.1) (@sigma_eq_unc A B u v pq) = transport B' pq.1 :=
destruct pq tr_pr1_sigma_eq
definition is_equiv_sigma_eq [instance] (u v : Σa, B a)
: is_equiv (@sigma_eq_unc A B u v) :=
adjointify sigma_eq_unc
(λp, ⟨p..1, p..2⟩)
sigma_eq_eta_unc
dpair_sigma_eq_unc
definition sigma_eq_equiv (u v : Σa, B a) : (u = v) ≃ (Σ(p : u.1 = v.1), u.2 =[p] v.2) :=
(equiv.mk sigma_eq_unc _)⁻¹ᵉ
definition dpair_eq_dpair_con (p1 : a = a' ) (q1 : b =[p1] b' )
(p2 : a' = a'') (q2 : b' =[p2] b'') :
dpair_eq_dpair (p1 ⬝ p2) (q1 ⬝o q2) = dpair_eq_dpair p1 q1 ⬝ dpair_eq_dpair p2 q2 :=
by induction q1; induction q2; reflexivity
definition sigma_eq_con (p1 : u.1 = v.1) (q1 : u.2 =[p1] v.2)
(p2 : v.1 = w.1) (q2 : v.2 =[p2] w.2) :
sigma_eq (p1 ⬝ p2) (q1 ⬝o q2) = sigma_eq p1 q1 ⬝ sigma_eq p2 q2 :=
by induction u; induction v; induction w; apply dpair_eq_dpair_con
local attribute dpair_eq_dpair [reducible]
definition dpair_eq_dpair_con_idp (p : a = a') (q : b =[p] b') :
dpair_eq_dpair p q = dpair_eq_dpair p !pathover_tr ⬝
dpair_eq_dpair idp (pathover_idp_of_eq (tr_eq_of_pathover q)) :=
by induction q; reflexivity
/- eq_pr1 commutes with the groupoid structure. -/
definition eq_pr1_idp (u : Σa, B a) : (refl u) ..1 = refl (u.1) := idp
definition eq_pr1_con (p : u = v) (q : v = w) : (p ⬝ q) ..1 = (p..1) ⬝ (q..1) := !ap_con
definition eq_pr1_inv (p : u = v) : p⁻¹ ..1 = (p..1)⁻¹ := !ap_inv
/- Applying dpair to one argument is the same as dpair_eq_dpair with reflexivity in the first place. -/
definition ap_dpair (q : b₁ = b₂) :
ap (sigma.mk a) q = dpair_eq_dpair idp (pathover_idp_of_eq q) :=
by induction q; reflexivity
/- Dependent transport is the same as transport along a sigma_eq. -/
definition transportD_eq_transport (p : a = a') (c : C a b) :
p ▸D c = transport (λu, C (u.1) (u.2)) (dpair_eq_dpair p !pathover_tr) c :=
by induction p; reflexivity
definition sigma_eq_eq_sigma_eq {p1 q1 : a = a'} {p2 : b =[p1] b'} {q2 : b =[q1] b'}
(r : p1 = q1) (s : p2 =[r] q2) : sigma_eq p1 p2 = sigma_eq q1 q2 :=
by induction s; reflexivity
/- A path between paths in a total space is commonly shown component wise. -/
definition sigma_eq2 {p q : u = v} (r : p..1 = q..1) (s : p..2 =[r] q..2)
: p = q :=
begin
induction p, induction u with u1 u2,
transitivity sigma_eq q..1 q..2,
apply sigma_eq_eq_sigma_eq r s,
apply sigma_eq_eta,
end
definition sigma_eq2_unc {p q : u = v} (rs : Σ(r : p..1 = q..1), p..2 =[r] q..2) : p = q :=
destruct rs sigma_eq2
definition ap_dpair_eq_dpair (f : Πa, B a → A') (p : a = a') (q : b =[p] b')
: ap (sigma.rec f) (dpair_eq_dpair p q) = apo011 f p q :=
by induction q; reflexivity
/- Transport -/
/- The concrete description of transport in sigmas (and also pis) is rather trickier than in the other types. In particular, these cannot be described just in terms of transport in simpler types; they require also the dependent transport [transportD].
In particular, this indicates why `transport` alone cannot be fully defined by induction on the structure of types, although Id-elim/transportD can be (cf. Observational Type Theory). A more thorough set of lemmas, along the lines of the present ones but dealing with Id-elim rather than just transport, might be nice to have eventually? -/
definition sigma_transport (p : a = a') (bc : Σ(b : B a), C a b)
: p ▸ bc = ⟨p ▸ bc.1, p ▸D bc.2⟩ :=
by induction p; induction bc; reflexivity
/- The special case when the second variable doesn't depend on the first is simpler. -/
definition sigma_transport_nondep {B : Type} {C : A → B → Type} (p : a = a')
(bc : Σ(b : B), C a b) : p ▸ bc = ⟨bc.1, p ▸ bc.2⟩ :=
by induction p; induction bc; reflexivity
/- Or if the second variable contains a first component that doesn't depend on the first. -/
definition sigma_transport2_nondep {C : A → Type} {D : Π a:A, B a → C a → Type} (p : a = a')
(bcd : Σ(b : B a) (c : C a), D a b c) : p ▸ bcd = ⟨p ▸ bcd.1, p ▸ bcd.2.1, p ▸D2 bcd.2.2⟩ :=
begin
induction p, induction bcd with b cd, induction cd, reflexivity
end
/- Pathovers -/
definition etao (p : a = a') (bc : Σ(b : B a), C a b)
: bc =[p] ⟨p ▸ bc.1, p ▸D bc.2⟩ :=
by induction p; induction bc; apply idpo
definition sigma_pathover (p : a = a') (u : Σ(b : B a), C a b) (v : Σ(b : B a'), C a' b)
(r : u.1 =[p] v.1) (s : u.2 =[apo011 C p r] v.2) : u =[p] v :=
begin
induction u, induction v, esimp at *, induction r,
esimp [apo011] at s, induction s using idp_rec_on, apply idpo
end
/-
TODO:
* define the projections from the type u =[p] v
* show that the uncurried version of sigma_pathover is an equivalence
-/
/- Functorial action -/
variables (f : A → A') (g : Πa, B a → B' (f a))
definition sigma_functor [unfold 7] (u : Σa, B a) : Σa', B' a' :=
⟨f u.1, g u.1 u.2⟩
definition total [reducible] [unfold 5] {B' : A → Type} (g : Πa, B a → B' a) (u : Σa, B a)
: Σa', B' a' :=
sigma_functor id g u
/- Equivalences -/
definition is_equiv_sigma_functor [H1 : is_equiv f] [H2 : Π a, is_equiv (g a)]
: is_equiv (sigma_functor f g) :=
adjointify (sigma_functor f g)
(sigma_functor f⁻¹ (λ(a' : A') (b' : B' a'),
((g (f⁻¹ a'))⁻¹ (transport B' (right_inv f a')⁻¹ b'))))
begin
intro u', induction u' with a' b',
apply sigma_eq (right_inv f a'),
rewrite [▸*,right_inv (g (f⁻¹ a')),▸*],
apply tr_pathover
end
begin
intro u,
induction u with a b,
apply (sigma_eq (left_inv f a)),
apply pathover_of_tr_eq,
rewrite [▸*,adj f,-(fn_tr_eq_tr_fn (left_inv f a) (λ a, (g a)⁻¹)),
▸*,tr_compose B' f,tr_inv_tr,left_inv]
end
definition sigma_equiv_sigma_of_is_equiv [constructor]
[H1 : is_equiv f] [H2 : Π a, is_equiv (g a)] : (Σa, B a) ≃ (Σa', B' a') :=
equiv.mk (sigma_functor f g) !is_equiv_sigma_functor
definition sigma_equiv_sigma [constructor] (Hf : A ≃ A') (Hg : Π a, B a ≃ B' (to_fun Hf a)) :
(Σa, B a) ≃ (Σa', B' a') :=
sigma_equiv_sigma_of_is_equiv (to_fun Hf) (λ a, to_fun (Hg a))
definition sigma_equiv_sigma_id [constructor] {B' : A → Type} (Hg : Π a, B a ≃ B' a)
: (Σa, B a) ≃ Σa, B' a :=
sigma_equiv_sigma equiv.refl Hg
definition ap_sigma_functor_eq_dpair (p : a = a') (q : b =[p] b') :
ap (sigma_functor f g) (sigma_eq p q) = sigma_eq (ap f p) (pathover.rec_on q idpo) :=
by induction q; reflexivity
-- definition ap_sigma_functor_eq (p : u.1 = v.1) (q : u.2 =[p] v.2)
-- : ap (sigma_functor f g) (sigma_eq p q) =
-- sigma_eq (ap f p)
-- ((tr_compose B' f p (g u.1 u.2))⁻¹ ⬝ (fn_tr_eq_tr_fn p g u.2)⁻¹ ⬝ ap (g v.1) q) :=
-- by induction u; induction v; apply ap_sigma_functor_eq_dpair
/- definition 3.11.9(i): Summing up a contractible family of types does nothing. -/
definition is_equiv_pr1 [instance] [constructor] (B : A → Type) [H : Π a, is_contr (B a)]
: is_equiv (@pr1 A B) :=
adjointify pr1
(λa, ⟨a, !center⟩)
(λa, idp)
(λu, sigma_eq idp (pathover_idp_of_eq !center_eq))
definition sigma_equiv_of_is_contr_right [constructor] [H : Π a, is_contr (B a)]
: (Σa, B a) ≃ A :=
equiv.mk pr1 _
/- definition 3.11.9(ii): Dually, summing up over a contractible type does nothing. -/
definition sigma_equiv_of_is_contr_left [constructor] (B : A → Type) [H : is_contr A]
: (Σa, B a) ≃ B (center A) :=
equiv.MK
(λu, (center_eq u.1)⁻¹ ▸ u.2)
(λb, ⟨!center, b⟩)
(λb, ap (λx, x ▸ b) !hprop_eq_of_is_contr)
(λu, sigma_eq !center_eq !tr_pathover)
/- Associativity -/
--this proof is harder than in Coq because we don't have eta definitionally for sigma
definition sigma_assoc_equiv [constructor] (C : (Σa, B a) → Type)
: (Σa b, C ⟨a, b⟩) ≃ (Σu, C u) :=
equiv.mk _ (adjointify
(λav, ⟨⟨av.1, av.2.1⟩, av.2.2⟩)
(λuc, ⟨uc.1.1, uc.1.2, !sigma.eta⁻¹ ▸ uc.2⟩)
begin intro uc, induction uc with u c, induction u, reflexivity end
begin intro av, induction av with a v, induction v, reflexivity end)
open prod prod.ops
definition assoc_equiv_prod [constructor] (C : (A × A') → Type) : (Σa a', C (a,a')) ≃ (Σu, C u) :=
equiv.mk _ (adjointify
(λav, ⟨(av.1, av.2.1), av.2.2⟩)
(λuc, ⟨pr₁ (uc.1), pr₂ (uc.1), !prod.eta⁻¹ ▸ uc.2⟩)
proof (λuc, destruct uc (λu, prod.destruct u (λa b c, idp))) qed
proof (λav, destruct av (λa v, destruct v (λb c, idp))) qed)
/- Symmetry -/
definition comm_equiv_unc (C : A × A' → Type) : (Σa a', C (a, a')) ≃ (Σa' a, C (a, a')) :=
calc
(Σa a', C (a, a')) ≃ Σu, C u : assoc_equiv_prod
... ≃ Σv, C (flip v) : sigma_equiv_sigma !prod_comm_equiv
(λu, prod.destruct u (λa a', equiv.refl))
... ≃ Σa' a, C (a, a') : assoc_equiv_prod
definition sigma_comm_equiv [constructor] (C : A → A' → Type)
: (Σa a', C a a') ≃ (Σa' a, C a a') :=
comm_equiv_unc (λu, C (prod.pr1 u) (prod.pr2 u))
definition equiv_prod [constructor] (A B : Type) : (Σ(a : A), B) ≃ A × B :=
equiv.mk _ (adjointify
(λs, (s.1, s.2))
(λp, ⟨pr₁ p, pr₂ p⟩)
proof (λp, prod.destruct p (λa b, idp)) qed
proof (λs, destruct s (λa b, idp)) qed)
definition comm_equiv_nondep (A B : Type) : (Σ(a : A), B) ≃ Σ(b : B), A :=
calc
(Σ(a : A), B) ≃ A × B : equiv_prod
... ≃ B × A : prod_comm_equiv
... ≃ Σ(b : B), A : equiv_prod
/- Interaction with other type constructors -/
definition sigma_empty_left [constructor] (B : empty → Type) : (Σx, B x) ≃ empty :=
begin
fapply equiv.MK,
{ intro v, induction v, contradiction},
{ intro x, contradiction},
{ intro x, contradiction},
{ intro v, induction v, contradiction},
end
definition sigma_empty_right [constructor] (A : Type) : (Σ(a : A), empty) ≃ empty :=
begin
fapply equiv.MK,
{ intro v, induction v, contradiction},
{ intro x, contradiction},
{ intro x, contradiction},
{ intro v, induction v, contradiction},
end
definition sigma_unit_left [constructor] (B : unit → Type) : (Σx, B x) ≃ B star :=
!sigma_equiv_of_is_contr_left
definition sigma_unit_right [constructor] (A : Type) : (Σ(a : A), unit) ≃ A :=
!sigma_equiv_of_is_contr_right
definition sigma_sum_left [constructor] (B : A + A' → Type)
: (Σp, B p) ≃ (Σa, B (inl a)) + (Σa, B (inr a)) :=
begin
fapply equiv.MK,
{ intro v,
induction v with p b, induction p: append (apply inl) (apply inr); constructor; assumption },
{ intro p, induction p with v v: induction v; constructor; assumption},
{ intro p, induction p with v v: induction v; reflexivity},
{ intro v, induction v with p b, induction p: reflexivity},
end
definition sigma_sum_right [constructor] (B C : A → Type)
: (Σa, B a + C a) ≃ (Σa, B a) + (Σa, C a) :=
begin
fapply equiv.MK,
{ intro v,
induction v with a p, induction p: append (apply inl) (apply inr); constructor; assumption},
{ intro p,
induction p with v v: induction v; constructor; append (apply inl) (apply inr); assumption},
{ intro p, induction p with v v: induction v; reflexivity},
{ intro v, induction v with a p, induction p: reflexivity},
end
/- ** Universal mapping properties -/
/- *** The positive universal property. -/
section
definition is_equiv_sigma_rec [instance] (C : (Σa, B a) → Type)
: is_equiv (sigma.rec : (Πa b, C ⟨a, b⟩) → Πab, C ab) :=
adjointify _ (λ g a b, g ⟨a, b⟩)
(λ g, proof eq_of_homotopy (λu, destruct u (λa b, idp)) qed)
(λ f, refl f)
definition equiv_sigma_rec (C : (Σa, B a) → Type)
: (Π(a : A) (b: B a), C ⟨a, b⟩) ≃ (Πxy, C xy) :=
equiv.mk sigma.rec _
/- *** The negative universal property. -/
protected definition coind_unc (fg : Σ(f : Πa, B a), Πa, C a (f a)) (a : A)
: Σ(b : B a), C a b :=
⟨fg.1 a, fg.2 a⟩
protected definition coind (f : Π a, B a) (g : Π a, C a (f a)) (a : A) : Σ(b : B a), C a b :=
sigma.coind_unc ⟨f, g⟩ a
--is the instance below dangerous?
--in Coq this can be done without function extensionality
definition is_equiv_coind [instance] (C : Πa, B a → Type)
: is_equiv (@sigma.coind_unc _ _ C) :=
adjointify _ (λ h, ⟨λa, (h a).1, λa, (h a).2⟩)
(λ h, proof eq_of_homotopy (λu, !sigma.eta) qed)
(λfg, destruct fg (λ(f : Π (a : A), B a) (g : Π (x : A), C x (f x)), proof idp qed))
definition sigma_pi_equiv_pi_sigma : (Σ(f : Πa, B a), Πa, C a (f a)) ≃ (Πa, Σb, C a b) :=
equiv.mk sigma.coind_unc _
end
/- Subtypes (sigma types whose second components are hprops) -/
definition subtype [reducible] {A : Type} (P : A → Type) [H : Πa, is_hprop (P a)] :=
Σ(a : A), P a
notation [parsing_only] `{` binder `|` r:(scoped:1 P, subtype P) `}` := r
/- To prove equality in a subtype, we only need equality of the first component. -/
definition subtype_eq [H : Πa, is_hprop (B a)] {u v : {a | B a}} : u.1 = v.1 → u = v :=
sigma_eq_unc ∘ inv pr1
definition is_equiv_subtype_eq [H : Πa, is_hprop (B a)] (u v : {a | B a})
: is_equiv (subtype_eq : u.1 = v.1 → u = v) :=
!is_equiv_compose
local attribute is_equiv_subtype_eq [instance]
definition equiv_subtype [H : Πa, is_hprop (B a)] (u v : {a | B a}) : (u.1 = v.1) ≃ (u = v) :=
equiv.mk !subtype_eq _
definition subtype_eq_inv {A : Type} {B : A → Type} [H : Πa, is_hprop (B a)] (u v : Σa, B a)
: u = v → u.1 = v.1 :=
subtype_eq⁻¹ᶠ
local attribute subtype_eq_inv [reducible]
definition is_equiv_subtype_eq_inv {A : Type} {B : A → Type} [H : Πa, is_hprop (B a)]
(u v : Σa, B a) : is_equiv (subtype_eq_inv u v) :=
_
/- truncatedness -/
theorem is_trunc_sigma (B : A → Type) (n : trunc_index)
[HA : is_trunc n A] [HB : Πa, is_trunc n (B a)] : is_trunc n (Σa, B a) :=
begin
revert A B HA HB,
induction n with n IH,
{ intro A B HA HB, fapply is_trunc_equiv_closed_rev, apply sigma_equiv_of_is_contr_left},
{ intro A B HA HB, apply is_trunc_succ_intro, intro u v,
apply is_trunc_equiv_closed_rev,
apply sigma_eq_equiv,
exact IH _ _ _ _}
end
theorem is_trunc_subtype (B : A → hprop) (n : trunc_index)
[HA : is_trunc (n.+1) A] : is_trunc (n.+1) (Σa, B a) :=
@(is_trunc_sigma B (n.+1)) _ (λa, !is_trunc_succ_of_is_hprop)
end sigma
attribute sigma.is_trunc_sigma [instance] [priority 1490]
attribute sigma.is_trunc_subtype [instance] [priority 1200]
|
c3681fd505b72a1345bf24dc6b774f4d90987ad7 | 1f6fe2f89976b14a4567ab298c35792b21f2e50b | /cohomology/serre.hlean | 035d1d3b7b2a0364ed86fae7dc0930bcfbec95b2 | [
"Apache-2.0"
] | permissive | jonas-frey/Spectral | e5c1c2f7bcac26aa55f7b1e041a81272a146198d | 72d521091525a4bc9a31cac859840efe9461cf66 | refs/heads/master | 1,610,235,743,345 | 1,505,417,795,000 | 1,505,417,795,000 | 102,653,342 | 0 | 0 | null | 1,504,728,483,000 | 1,504,728,483,000 | null | UTF-8 | Lean | false | false | 9,580 | hlean | import ..algebra.spectral_sequence ..spectrum.trunc .basic
open eq spectrum trunc is_trunc pointed int EM algebra left_module fiber lift equiv is_equiv
cohomology group sigma unit is_conn
set_option pp.binder_types true
/- Eilenberg MacLane spaces are the fibers of the Postnikov system of a type -/
namespace pointed
definition postnikov_map [constructor] (A : Type*) (n : ℕ₋₂) : ptrunc (n.+1) A →* ptrunc n A :=
ptrunc.elim (n.+1) (ptr n A)
definition ptrunc_functor_postnikov_map {A B : Type*} (n : ℕ₋₂) (f : A →* B) :
ptrunc_functor n f ∘* postnikov_map A n ~* ptrunc.elim (n.+1) (!ptr ∘* f) :=
begin
fapply phomotopy.mk,
{ intro x, induction x with a, reflexivity },
{ reflexivity }
end
section
open nat group
definition pfiber_postnikov_map (A : Type*) (n : ℕ) :
pfiber (postnikov_map A n) ≃* EM_type A (n+1) :=
begin
symmetry, apply EM_type_pequiv,
{ symmetry, refine _ ⬝g ghomotopy_group_ptrunc (n+1) A,
exact chain_complex.LES_isomorphism_of_trivial_cod _ _
(trivial_homotopy_group_of_is_trunc _ (self_lt_succ n))
(trivial_homotopy_group_of_is_trunc _ (le_succ _)) },
{ apply is_conn_fun_trunc_elim, apply is_conn_fun_tr },
{ have is_trunc (n+1) (ptrunc n.+1 A), from !is_trunc_trunc,
have is_trunc ((n+1).+1) (ptrunc n A), by do 2 apply is_trunc_succ, apply is_trunc_trunc,
apply is_trunc_pfiber }
end
end
definition postnikov_map_natural {A B : Type*} (f : A →* B) (n : ℕ₋₂) :
psquare (postnikov_map A n) (postnikov_map B n)
(ptrunc_functor (n.+1) f) (ptrunc_functor n f) :=
!ptrunc_functor_postnikov_map ⬝* !ptrunc_elim_ptrunc_functor⁻¹*
definition is_equiv_postnikov_map (A : Type*) {n k : ℕ₋₂} [HA : is_trunc k A] (H : k ≤ n) :
is_equiv (postnikov_map A n) :=
begin
apply is_equiv_of_equiv_of_homotopy
(ptrunc_pequiv_ptrunc_of_is_trunc (trunc_index.le.step H) H HA),
intro x, induction x, reflexivity
end
definition encode_ap1_gen_tr (n : ℕ₋₂) {A : Type*} {a a' : A} (p : a = a') :
trunc.encode (ap1_gen tr idp idp p) = tr p :> trunc n (a = a') :=
by induction p; reflexivity
definition ap1_postnikov_map (A : Type*) (n : ℕ₋₂) :
psquare (Ω→ (postnikov_map A (n.+1))) (postnikov_map (Ω A) n)
(loop_ptrunc_pequiv (n.+1) A) (loop_ptrunc_pequiv n A) :=
have psquare (postnikov_map (Ω A) n) (Ω→ (postnikov_map A (n.+1)))
(loop_ptrunc_pequiv (n.+1) A)⁻¹ᵉ* (loop_ptrunc_pequiv n A)⁻¹ᵉ*,
begin
refine _ ⬝* !ap1_ptrunc_elim⁻¹*, apply pinv_left_phomotopy_of_phomotopy,
fapply phomotopy.mk,
{ intro x, induction x with p, exact !encode_ap1_gen_tr⁻¹ },
{ reflexivity }
end,
this⁻¹ᵛ*
end pointed open pointed
namespace spectrum
definition postnikov_smap [constructor] (X : spectrum) (k : ℤ) :
strunc k X →ₛ strunc (k - 1) X :=
strunc_elim (str (k - 1) X) (is_strunc_strunc_pred X k)
definition postnikov_map_pred (A : Type*) (n : ℕ₋₂) :
ptrunc n A →* ptrunc (trunc_index.pred n) A :=
begin cases n with n, exact !pid, exact postnikov_map A n end
definition pfiber_postnikov_map_pred (A : Type*) (n : ℕ) :
pfiber (postnikov_map_pred A n) ≃* EM_type A n :=
begin
cases n with n,
apply pfiber_pequiv_of_is_contr, apply is_contr_ptrunc_minus_one,
exact pfiber_postnikov_map A n
end
definition pfiber_postnikov_map_pred' (A : spectrum) (n k l : ℤ) (p : n + k = l) :
pfiber (postnikov_map_pred (A k) (maxm2 l)) ≃* EM_spectrum (πₛ[n] A) l :=
begin
cases l with l l,
{ refine pfiber_postnikov_map_pred (A k) l ⬝e* _,
exact EM_type_pequiv_EM A p },
{ apply pequiv_of_is_contr, apply is_contr_pfiber_pid,
apply is_contr_EM_spectrum_neg }
end
definition psquare_postnikov_map_ptrunc_elim (A : Type*) {n k l : ℕ₋₂} (H : is_trunc n (ptrunc k A))
(p : n = l.+1) (q : k = l) :
psquare (ptrunc.elim n (ptr k A)) (postnikov_map A l)
(ptrunc_change_index p A) (ptrunc_change_index q A) :=
begin
induction q, cases p,
refine _ ⬝pv* pvrfl,
apply ptrunc_elim_phomotopy2,
reflexivity
end
definition postnikov_smap_postnikov_map (A : spectrum) (n k l : ℤ) (p : n + k = l) :
psquare (postnikov_smap A n k) (postnikov_map_pred (A k) (maxm2 l))
(ptrunc_maxm2_change_int p (A k)) (ptrunc_maxm2_pred (A k) (ap pred p⁻¹ ⬝ add.right_comm n k (- 1))) :=
begin
cases l with l,
{ cases l with l, apply phomotopy_of_is_contr_cod_pmap, apply is_contr_ptrunc_minus_one,
refine psquare_postnikov_map_ptrunc_elim (A k) _ _ _ ⬝hp* _,
exact ap maxm2 (add.right_comm n (- 1) k ⬝ ap pred p ⬝ !pred_succ),
apply ptrunc_maxm2_pred_nat },
{ apply phomotopy_of_is_contr_cod_pmap, apply is_trunc_trunc }
end
definition sfiber_postnikov_smap_pequiv (A : spectrum) (n : ℤ) (k : ℤ) :
sfiber (postnikov_smap A n) k ≃* ssuspn n (EM_spectrum (πₛ[n] A)) k :=
proof
pfiber_pequiv_of_square _ _ (postnikov_smap_postnikov_map A n k (n + k) idp) ⬝e*
pfiber_postnikov_map_pred' A n k _ idp ⬝e*
pequiv_ap (EM_spectrum (πₛ[n] A)) (add.comm n k)
qed
section atiyah_hirzebruch
parameters {X : Type*} (Y : X → spectrum) (s₀ : ℤ) (H : Πx, is_strunc s₀ (Y x))
definition atiyah_hirzebruch_exact_couple : exact_couple rℤ Z2 :=
@exact_couple_sequence (λs, spi X (λx, strunc s (Y x)))
(λs, spi_compose_left (λx, postnikov_smap (Y x) s))
include H
definition atiyah_hirzebruch_ub ⦃s n : ℤ⦄ (Hs : s ≤ n - 1) :
is_contr (πₛ[n] (spi X (λx, strunc s (Y x)))) :=
begin
refine trivial_shomotopy_group_of_is_strunc _ _ (lt_of_le_sub_one Hs),
apply is_strunc_spi, intro x, exact is_strunc_strunc _ _
end
definition atiyah_hirzebruch_lb ⦃s n : ℤ⦄ (Hs : s ≥ s₀ + 1) :
is_equiv (spi_compose_left (λx, postnikov_smap (Y x) s) n) :=
begin
refine is_equiv_of_equiv_of_homotopy
(ppi_pequiv_right (λx, ptrunc_pequiv_ptrunc_of_is_trunc _ _ (H x n))) _,
{ intro x, apply maxm2_monotone, apply add_le_add_right, exact le.trans !le_add_one Hs },
{ intro x, apply maxm2_monotone, apply add_le_add_right, exact le_sub_one_of_lt Hs },
intro f, apply eq_of_phomotopy,
apply pmap_compose_ppi_phomotopy_left, intro x,
fapply phomotopy.mk,
{ refine @trunc.rec _ _ _ _ _,
{ intro x, apply is_trunc_eq,
assert H3 : maxm2 (s - 1 + n) ≤ (maxm2 (s + n)).+1,
{ refine trunc_index.le_succ (maxm2_monotone (le.trans (le_of_eq !add.right_comm)
!sub_one_le)) },
exact @is_trunc_of_le _ _ _ H3 !is_trunc_trunc },
intro a, reflexivity },
reflexivity
end
definition is_bounded_atiyah_hirzebruch : is_bounded atiyah_hirzebruch_exact_couple :=
is_bounded_sequence _ s₀ (λn, n - 1) atiyah_hirzebruch_lb atiyah_hirzebruch_ub
definition atiyah_hirzebruch_convergence' :
(λn s, πₛ[n] (sfiber (spi_compose_left (λx, postnikov_smap (Y x) s)))) ⟹ᵍ
(λn, πₛ[n] (spi X (λx, strunc s₀ (Y x)))) :=
converges_to_sequence _ s₀ (λn, n - 1) atiyah_hirzebruch_lb atiyah_hirzebruch_ub
definition atiyah_hirzebruch_convergence :
(λn s, opH^-(n-s)[(x : X), πₛ[s] (Y x)]) ⟹ᵍ (λn, pH^-n[(x : X), Y x]) :=
converges_to_g_isomorphism atiyah_hirzebruch_convergence'
begin
intro n s,
refine _ ⬝g (parametrized_cohomology_isomorphism_shomotopy_group_spi _ idp)⁻¹ᵍ,
refine _ ⬝g !shomotopy_group_ssuspn,
apply shomotopy_group_isomorphism_of_pequiv n, intro k,
refine !pfiber_pppi_compose_left ⬝e* _,
exact ppi_pequiv_right (λx, sfiber_postnikov_smap_pequiv (Y x) s k)
end
begin
intro n,
refine _ ⬝g (parametrized_cohomology_isomorphism_shomotopy_group_spi _ idp)⁻¹ᵍ,
apply shomotopy_group_isomorphism_of_pequiv, intro k,
exact ppi_pequiv_right (λx, ptrunc_pequiv (maxm2 (s₀ + k)) (Y x k)),
end
end atiyah_hirzebruch
section unreduced_atiyah_hirzebruch
definition unreduced_atiyah_hirzebruch_convergence {X : Type} (Y : X → spectrum) (s₀ : ℤ)
(H : Πx, is_strunc s₀ (Y x)) :
(λn s, uopH^-(n-s)[(x : X), πₛ[s] (Y x)]) ⟹ᵍ (λn, upH^-n[(x : X), Y x]) :=
converges_to_g_isomorphism
(@atiyah_hirzebruch_convergence X₊ (add_point_spectrum Y) s₀ (is_strunc_add_point_spectrum H))
begin
intro n s, refine _ ⬝g !uopH_isomorphism_opH⁻¹ᵍ,
apply ordinary_parametrized_cohomology_isomorphism_right,
intro x,
apply shomotopy_group_add_point_spectrum
end
begin
intro n, reflexivity
end
end unreduced_atiyah_hirzebruch
section serre
variables {X : Type} (F : X → Type) (Y : spectrum) (s₀ : ℤ) (H : is_strunc s₀ Y)
include H
definition serre_convergence :
(λn s, uopH^-(n-s)[(x : X), uH^-s[F x, Y]]) ⟹ᵍ (λn, uH^-n[Σ(x : X), F x, Y]) :=
proof
converges_to_g_isomorphism
(unreduced_atiyah_hirzebruch_convergence
(λx, sp_ucotensor (F x) Y) s₀
(λx, is_strunc_sp_ucotensor s₀ (F x) H))
begin
intro n s,
refine unreduced_ordinary_parametrized_cohomology_isomorphism_right _ (-(n-s)),
intro x,
exact (unreduced_cohomology_isomorphism_shomotopy_group_sp_ucotensor _ _ idp)⁻¹ᵍ
end
begin
intro n,
refine unreduced_parametrized_cohomology_isomorphism_shomotopy_group_supi _ idp ⬝g _,
refine _ ⬝g (unreduced_cohomology_isomorphism_shomotopy_group_sp_ucotensor _ _ idp)⁻¹ᵍ,
apply shomotopy_group_isomorphism_of_pequiv, intro k,
exact (sigma_pumap F (Y k))⁻¹ᵉ*
end
qed
end serre
end spectrum
|
a53bef090098bff1dce82c1b53ec3a4c65eabda5 | 70f8755415fa7a17f87402cde4651e9f4db1b5bb | /src/mvqpf/fix.lean | b03afaa3c7058bdc321adbd524b3db0f8a3d9208 | [
"Apache-2.0"
] | permissive | shingarov/qpf | ab935dc2298db12c87ac011a2e4d2c27e0bdef4b | debe2eacb8cf46b21aba2eaf3f2e20940da0263b | refs/heads/master | 1,653,705,576,607 | 1,570,136,035,000 | 1,570,136,035,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 10,339 | lean | /-
Copyright (c) 2018 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Jeremy Avigad
The initial algebra of a multivariate qpf is again a qpf.
-/
import ..mvpfunctor.W .basic
universes u v
namespace mvqpf
open typevec
open mvfunctor (liftp liftr)
variables {n : ℕ} {F : typevec.{u} (n+1) → Type u} [mvfunctor F] [q : mvqpf F]
include q
/-- does recursion on `q.P.W` using `g : F α → α` rather than `g : P α → α` -/
def recF {α : typevec n} {β : Type*} (g : F (α.append1 β) → β) : q.P.W α → β :=
q.P.W_rec (λ a f' f rec, g (abs ⟨a, split_fun f' rec⟩))
theorem recF_eq {α : typevec n} {β : Type*} (g : F (α.append1 β) → β)
(a : q.P.A) (f' : q.P.drop.B a ⟹ α) (f : q.P.last.B a → q.P.W α) :
recF g (q.P.W_mk a f' f) = g (abs ⟨a, split_fun f' (recF g ∘ f)⟩) :=
by rw [recF, mvpfunctor.W_rec_eq]; refl
theorem recF_eq' {α : typevec n} {β : Type*} (g : F (α.append1 β) → β)
(x : q.P.W α) :
recF g x = g (abs ((append_fun id (recF g)) <$$> q.P.W_dest' x)) :=
begin
apply q.P.W_cases _ x,
intros a f' f,
rw [recF_eq, q.P.W_dest'_W_mk, mvpfunctor.map_eq, append_fun_comp_split_fun,
typevec.id_comp]
end
inductive Wequiv {α : typevec n} : q.P.W α → q.P.W α → Prop
| ind (a : q.P.A) (f' : q.P.drop.B a ⟹ α) (f₀ f₁ : q.P.last.B a → q.P.W α) :
(∀ x, Wequiv (f₀ x) (f₁ x)) → Wequiv (q.P.W_mk a f' f₀) (q.P.W_mk a f' f₁)
| abs (a₀ : q.P.A) (f'₀ : q.P.drop.B a₀ ⟹ α) (f₀ : q.P.last.B a₀ → q.P.W α)
(a₁ : q.P.A) (f'₁ : q.P.drop.B a₁ ⟹ α) (f₁ : q.P.last.B a₁ → q.P.W α) :
abs ⟨a₀, q.P.append_contents f'₀ f₀⟩ = abs ⟨a₁, q.P.append_contents f'₁ f₁⟩ →
Wequiv (q.P.W_mk a₀ f'₀ f₀) (q.P.W_mk a₁ f'₁ f₁)
| trans (u v w : q.P.W α) : Wequiv u v → Wequiv v w → Wequiv u w
theorem recF_eq_of_Wequiv (α : typevec n) {β : Type*} (u : F (α.append1 β) → β)
(x y : q.P.W α) :
Wequiv x y → recF u x = recF u y :=
begin
apply q.P.W_cases _ x,
intros a₀ f'₀ f₀,
apply q.P.W_cases _ y,
intros a₁ f'₁ f₁,
intro h, induction h,
case mvqpf.Wequiv.ind : a f' f₀ f₁ h ih { simp only [recF_eq, function.comp, ih] },
case mvqpf.Wequiv.abs : a₀ f'₀ f₀ a₁ f'₁ f₁ h ih
{ simp only [recF_eq', abs_map, mvpfunctor.W_dest'_W_mk, h] },
case mvqpf.Wequiv.trans : x y z e₁ e₂ ih₁ ih₂
{ exact eq.trans ih₁ ih₂ }
end
theorem Wequiv.abs' {α : typevec n} (x y : q.P.W α)
(h : abs (q.P.W_dest' x) = abs (q.P.W_dest' y)) :
Wequiv x y :=
begin
revert h,
apply q.P.W_cases _ x,
intros a₀ f'₀ f₀,
apply q.P.W_cases _ y,
intros a₁ f'₁ f₁,
apply Wequiv.abs
end
theorem Wequiv.refl {α : typevec n} (x : q.P.W α) : Wequiv x x :=
by apply q.P.W_cases _ x; intros a f' f; exact Wequiv.abs a f' f a f' f rfl
theorem Wequiv.symm {α : typevec n} (x y : q.P.W α) : Wequiv x y → Wequiv y x :=
begin
intro h, induction h,
case mvqpf.Wequiv.ind : a f' f₀ f₁ h ih
{ exact Wequiv.ind _ _ _ _ ih },
case mvqpf.Wequiv.abs : a₀ f'₀ f₀ a₁ f'₁ f₁ h ih
{ exact Wequiv.abs _ _ _ _ _ _ h.symm },
case mvqpf.Wequiv.trans : x y z e₁ e₂ ih₁ ih₂
{ exact mvqpf.Wequiv.trans _ _ _ ih₂ ih₁}
end
/-- maps every element of the W type to a canonical representative -/
def Wrepr {α : typevec n} : q.P.W α → q.P.W α := recF (q.P.W_mk' ∘ repr)
theorem Wrepr_W_mk {α : typevec n}
(a : q.P.A) (f' : q.P.drop.B a ⟹ α) (f : q.P.last.B a → q.P.W α) :
Wrepr (q.P.W_mk a f' f) =
q.P.W_mk' (repr (abs ((append_fun id Wrepr) <$$> ⟨a, q.P.append_contents f' f⟩))) :=
by rw [Wrepr, recF_eq', q.P.W_dest'_W_mk]; refl
theorem Wrepr_equiv {α : typevec n} (x : q.P.W α) : Wequiv (Wrepr x) x :=
begin
apply q.P.W_ind _ x, intros a f' f ih,
apply Wequiv.trans _ (q.P.W_mk' ((append_fun id Wrepr) <$$> ⟨a, q.P.append_contents f' f⟩)),
{ apply Wequiv.abs',
rw [Wrepr_W_mk, q.P.W_dest'_W_mk', q.P.W_dest'_W_mk', abs_repr] },
rw [q.P.map_eq, mvpfunctor.W_mk', append_fun_comp_split_fun, id_comp],
apply Wequiv.ind, exact ih
end
theorem Wequiv_map {α β : typevec n} (g : α ⟹ β) (x y : q.P.W α) :
Wequiv x y → Wequiv (g <$$> x) (g <$$> y) :=
begin
intro h, induction h,
case mvqpf.Wequiv.ind : a f' f₀ f₁ h ih
{ rw [q.P.W_map_W_mk, q.P.W_map_W_mk], apply Wequiv.ind, apply ih },
case mvqpf.Wequiv.abs : a₀ f'₀ f₀ a₁ f'₁ f₁ h ih
{ rw [q.P.W_map_W_mk, q.P.W_map_W_mk], apply Wequiv.abs,
show abs (q.P.apply_append1 a₀ (g ⊚ f'₀) (λ x, q.P.W_map g (f₀ x))) =
abs (q.P.apply_append1 a₁ (g ⊚ f'₁) (λ x, q.P.W_map g (f₁ x))),
rw [←q.P.map_apply_append1, ←q.P.map_apply_append1, abs_map, abs_map, h]},
case mvqpf.Wequiv.trans : x y z e₁ e₂ ih₁ ih₂
{ apply mvqpf.Wequiv.trans, apply ih₁, apply ih₂ }
end
/-
Define the fixed point as the quotient of trees under the equivalence relation.
-/
def W_setoid (α : typevec n) : setoid (q.P.W α) :=
⟨Wequiv, @Wequiv.refl _ _ _ _ _, @Wequiv.symm _ _ _ _ _, @Wequiv.trans _ _ _ _ _⟩
local attribute [instance] W_setoid
def fix {n : ℕ} (F : typevec (n+1) → Type*) [mvfunctor F] [q : mvqpf F] (α : typevec n) :=
quotient (W_setoid α : setoid (q.P.W α))
def fix.map {α β : typevec n} (g : α ⟹ β) : fix F α → fix F β :=
quotient.lift (λ x : q.P.W α, ⟦q.P.W_map g x⟧)
(λ a b h, quot.sound (Wequiv_map _ _ _ h))
instance fix.mvfunctor : mvfunctor (fix F) :=
{ map := @fix.map _ _ _ _}
variable {α : typevec.{u} n}
-- TODO: should this be quotient.lift?
def fix.rec {β : Type u} (g : F (append1 α β) → β) : fix F α → β :=
quot.lift (recF g) (recF_eq_of_Wequiv α g)
def fix_to_W : fix F α → q.P.W α :=
quotient.lift Wrepr (recF_eq_of_Wequiv α (λ x, q.P.W_mk' (repr x)))
def fix.mk (x : F (append1 α (fix F α))) : fix F α :=
quot.mk _ (q.P.W_mk' (append_fun id fix_to_W <$$> repr x))
def fix.dest : fix F α → F (append1 α (fix F α)) :=
fix.rec (mvfunctor.map (append_fun id fix.mk))
theorem fix.rec_eq {β : Type u} (g : F (append1 α β) → β) (x : F (append1 α (fix F α))) :
fix.rec g (fix.mk x) = g (append_fun id (fix.rec g) <$$> x) :=
have recF g ∘ fix_to_W = fix.rec g,
by { apply funext, apply quotient.ind, intro x, apply recF_eq_of_Wequiv,
apply Wrepr_equiv },
begin
conv { to_lhs, rw [fix.rec, fix.mk], dsimp },
cases h : repr x with a f,
rw [mvpfunctor.map_eq, recF_eq', ←mvpfunctor.map_eq, mvpfunctor.W_dest'_W_mk'],
rw [←mvpfunctor.comp_map, abs_map, ←h, abs_repr, ←append_fun_comp, id_comp, this]
end
theorem fix.ind_aux (a : q.P.A) (f' : q.P.drop.B a ⟹ α) (f : q.P.last.B a → q.P.W α) :
fix.mk (abs ⟨a, q.P.append_contents f' (λ x, ⟦f x⟧)⟩) = ⟦q.P.W_mk a f' f⟧ :=
have fix.mk (abs ⟨a, q.P.append_contents f' (λ x, ⟦f x⟧)⟩) = ⟦Wrepr (q.P.W_mk a f' f)⟧,
begin
apply quot.sound, apply Wequiv.abs',
rw [mvpfunctor.W_dest'_W_mk', abs_map, abs_repr, ←abs_map, mvpfunctor.map_eq],
conv { to_rhs, rw [Wrepr_W_mk, q.P.W_dest'_W_mk', abs_repr, mvpfunctor.map_eq] },
congr' 2, rw [mvpfunctor.append_contents, mvpfunctor.append_contents],
rw [append_fun, append_fun, ←split_fun_comp, ←split_fun_comp],
reflexivity
end,
by { rw this, apply quot.sound, apply Wrepr_equiv }
theorem fix.ind_rec {β : Type*} (g₁ g₂ : fix F α → β)
(h : ∀ x : F (append1 α (fix F α)),
(append_fun id g₁) <$$> x = (append_fun id g₂) <$$> x → g₁ (fix.mk x) = g₂ (fix.mk x)) :
∀ x, g₁ x = g₂ x :=
begin
apply quot.ind,
intro x,
apply q.P.W_ind _ x, intros a f' f ih,
show g₁ ⟦q.P.W_mk a f' f⟧ = g₂ ⟦q.P.W_mk a f' f⟧,
rw [←fix.ind_aux a f' f], apply h,
rw [←abs_map, ←abs_map, mvpfunctor.map_eq, mvpfunctor.map_eq],
congr' 2,
rw [mvpfunctor.append_contents, append_fun, append_fun, ←split_fun_comp, ←split_fun_comp],
have : g₁ ∘ (λ x, ⟦f x⟧) = g₂ ∘ (λ x, ⟦f x⟧),
{ ext x, exact ih x },
rw this
end
theorem fix.rec_unique {β : Type*} (g : F (append1 α β) → β) (h : fix F α → β)
(hyp : ∀ x, h (fix.mk x) = g (append_fun id h <$$> x)) :
fix.rec g = h :=
begin
ext x,
apply fix.ind_rec,
intros x hyp',
rw [hyp, ←hyp', fix.rec_eq]
end
theorem fix.mk_dest (x : fix F α) : fix.mk (fix.dest x) = x :=
begin
change (fix.mk ∘ fix.dest) x = x,
apply fix.ind_rec,
intro x, dsimp,
rw [fix.dest, fix.rec_eq, ←comp_map, ←append_fun_comp, id_comp],
intro h, rw h,
show fix.mk (append_fun id id <$$> x) = fix.mk x,
rw [append_fun_id_id, id_map]
end
theorem fix.dest_mk (x : F (append1 α (fix F α))) : fix.dest (fix.mk x) = x :=
begin
unfold fix.dest, rw [fix.rec_eq, ←fix.dest, ←comp_map],
conv { to_rhs, rw ←(id_map x) },
rw [←append_fun_comp, id_comp],
have : fix.mk ∘ fix.dest = id, {ext x, apply fix.mk_dest },
rw [this, append_fun_id_id]
end
theorem fix.ind {α : typevec n} (p : fix F α → Prop)
(h : ∀ x : F (α.append1 (fix F α)), liftp (pred_last α p) x → p (fix.mk x)) :
∀ x, p x :=
begin
apply quot.ind,
intro x,
apply q.P.W_ind _ x, intros a f' f ih,
change p ⟦q.P.W_mk a f' f⟧,
rw [←fix.ind_aux a f' f],
apply h,
rw mvqpf.liftp_iff,
refine ⟨_, _, rfl, _⟩,
intros i j,
cases i, { triv },
apply ih
end
instance mvqpf_fix : mvqpf (fix F) :=
{ P := q.P.Wp,
abs := λ α, quot.mk Wequiv,
repr' := λ α, fix_to_W,
abs_repr' := by { intros α, apply quot.ind, intro a, apply quot.sound, apply Wrepr_equiv },
abs_map :=
begin
intros α β g x, conv { to_rhs, dsimp [mvfunctor.map]},
rw fix.map, apply quot.sound,
apply Wequiv.refl
end }
def fix.drec {β : fix F α → Type u} (g : Π x : F (α ::: sigma β), β (fix.mk $ (id ::: sigma.fst) <$$> x)) (x : fix F α) : β x :=
let y := @fix.rec _ F _ _ α (sigma β) (λ i, ⟨_,g i⟩) x in
have x = y.1,
by { symmetry, dsimp [y], apply fix.ind_rec _ id _ x, intros x' ih,
rw fix.rec_eq, dsimp, simp [append_fun_id_id] at ih,
congr, conv { to_rhs, rw [← ih] }, rw [mvfunctor.map_map,← append_fun_comp,id_comp], },
cast (by rw this) y.2
end mvqpf
|
a7912479debcec67c7fc3108c0bb415267eb4b88 | 42610cc2e5db9c90269470365e6056df0122eaa0 | /library/theories/finite_group_theory/extra_action.lean | d41d287fc1ce00a5c42c02e54078a1b1a5b600b5 | [
"Apache-2.0"
] | permissive | tomsib2001/lean | 2ab59bfaebd24a62109f800dcf4a7139ebd73858 | eb639a7d53fb40175bea5c8da86b51d14bb91f76 | refs/heads/master | 1,586,128,387,740 | 1,468,968,950,000 | 1,468,968,950,000 | 61,027,234 | 0 | 0 | null | 1,465,813,585,000 | 1,465,813,585,000 | null | UTF-8 | Lean | false | false | 28,117 | lean | import algebra.group data theories.finite_group_theory.hom theories.finite_group_theory.perm theories.finite_group_theory.finsubg theories.finite_group_theory.action data.finset.extra_finset data.finset
import data.finset.partition
import theories.finite_group_theory.extra_finsubg
-- namespace group_theory
open finset function perm group_theory nat
lemma eq_im_of_eq_f {A B : Type} [decidable_eq B] (f g : A → B) (S : finset A) : f = g → f ' S = g ' S := take Hfg, by rewrite Hfg
local attribute perm.f [coercion]
section action_on_subset
-- structure action_on [class]
end action_on_subset
section conjugation_action
variables {G : Type} [Hgr : group G] [ Hft : fintype G]
include Hgr Hft
definition action_by_conj : G → perm G :=
take g, perm.mk (conj_by g) (conj_inj g)
variable [Hdec : decidable_eq G]
include Hdec
lemma conj_by_compose (g1 g2 : G) : conj_by (g1 * g2) = (conj_by g1)∘(conj_by g2) :=
funext (take x, begin rewrite conj_compose end)
lemma action_by_conj_hom : homomorphic (@action_by_conj G _ _) :=
take (g1 g2 : G),
eq.symm (calc
action_by_conj g1 * action_by_conj g2 = perm.mk ((conj_by g1)∘(conj_by g2)) _ : rfl
... = perm.mk ((conj_by (g1 * g2))) (conj_inj _) : begin congruence, rewrite conj_by_compose end
... = action_by_conj (g1 * g2) : rfl)
-- lemma action_by_conj_inj : injective (@action_by_conj G _ _) := sorry
-- lemma action_by_conj_is_iso [instance] : is_iso_class (@action_by_conj G _ _) :=
-- is_iso_class.mk action_by_conj_hom action_by_conj_inj
lemma conj_by_im_inj (g : G) : injective (image (conj_by g)) :=
begin
apply injective_image,
exact (conj_inj g)
end
definition action_by_conj_on_finsets : G → perm (finset G) :=
take g, perm.mk (image (conj_by g)) (conj_by_im_inj g)
lemma action_by_conj_on_finsets_inj : injective (@action_by_conj_on_finsets G _ _) := sorry
lemma conj_by_image_compose (g1 g2 : G) : image (conj_by g1) ∘ image (conj_by g2) = image (conj_by (g1 * g2)) :=
funext (take s,
begin
rewrite conj_by_compose,
rewrite image_comp
end)
lemma action_by_conj_on_finsets_hom :
homomorphic (@action_by_conj_on_finsets G Hgr Hft Hdec) :=
take (g1 g2 : G),
eq.symm (calc
action_by_conj_on_finsets g1 * action_by_conj_on_finsets g2 = perm.mk ((image (conj_by g1))∘(image (conj_by g2))) _ : rfl
... = perm.mk ((image (conj_by (g1 * g2)))) (conj_by_im_inj _) : begin congruence, exact !conj_by_image_compose end
... = action_by_conj_on_finsets (g1 * g2) : rfl)
definition conj_on_finsets_hom [instance] : is_hom_class (@action_by_conj_on_finsets G Hgr Hft Hdec) := is_hom_class.mk action_by_conj_on_finsets_hom
end conjugation_action
section action_by_conj
variables {G : Type} [ambientG : group G] [finG : fintype G] [deceqG : decidable_eq G]
include ambientG deceqG finG
-- set_option pp.implicit true
-- set_option pp.notation false
lemma conj_im_id (H : finset G) : conj_by 1 ' H = H :=
have conj_is_id : (conj_by : G → G → G) 1 = id, from funext (take x, by rewrite conj_id),
begin rewrite [conj_is_id],
rewrite image_id,
end
definition conj_subsets : G → group_theory.perm (finset G) :=
λ (g : G), perm.mk (λ H, image (conj_by g) H)
(take H1 H2 Heqg,
have H : conj_by (g⁻¹) ' (conj_by g ' H1) = conj_by (g⁻¹) ' (conj_by g ' H2), from by rewrite Heqg,
begin
rewrite -image_comp at H,
rewrite -image_comp at H,
rewrite -conj_by_compose at H,
rewrite (mul.left_inv g) at H,
revert H,
do 2 rewrite conj_im_id,
simp
end
)
lemma perm_of_conj (g : G) : perm.f (conj_subsets g) = λ H, image (conj_by g) H := rfl
-- set_option pp.implicit true
-- set_option pp.notation false
local attribute perm.mul [reducible]
lemma conj_subsets_mult (g1 g2: G) : perm.mul (conj_subsets g1) (conj_subsets g2) = conj_subsets (g1 * g2) :=
begin
apply eq_of_feq,
rewrite perm_of_conj,
rewrite ↑perm.mul,
do 2 rewrite perm_of_conj,
rewrite conj_by_image_compose
end
lemma homomorphic_conj_subsets : homomorphic (conj_subsets : G → group_theory.perm (finset G)) := take g1 g2,
have conj_subsets g1 * conj_subsets g2 = perm.mul (conj_subsets g1) (conj_subsets g2), from rfl,
begin
rewrite [this,conj_subsets_mult],
end
definition is_hom_conj_subsets [instance] : @is_hom_class G (perm (finset G)) _ _ conj_subsets := is_hom_class.mk homomorphic_conj_subsets
end action_by_conj
section partial_actions
open finset function
-- local attribute perm.f [coercion]
-- aT is the type of the acting group
-- rT is the return type of the set on which the action is done
variables {aT rT : Type} [group aT] [fintype rT] [fintype aT]
-- variable (D : finset aT) -- the domain
variable [Hdeceq_aT : decidable_eq aT]
variable [Hdeceq_rT : decidable_eq rT]
section defs
variable (D : finset aT)
variable (to : rT → aT → rT)
definition act_morph (x : rT) :=
forall (a b : aT), a ∈ D → b ∈ D → to x (a * b) = to (to x a) b
definition left_injective {A B C : Type} (f : A → B → C) := forall (y: B), injective (λ x, f x y)
definition is_action [class] := left_injective to ∧ ∀ (x : rT), act_morph D to x
-- definition act_dom D to := -- not sure how to define this one
set_option formatter.hide_full_terms false
include Hdeceq_aT
variable [Hact_to : is_action D to]
include Hact_to
definition actm a :=
if a ∈ D then (λ x, to x a) else (id : rT → rT)
definition actm_inj (a : aT) :
injective (actm D to a) := take x y,
begin cases decidable.em (a ∈ D) with aD naD,
rewrite ↑actm,
rewrite (if_pos aD),
apply ((and.left Hact_to)),
rewrite [↑actm,(if_neg naD),↑id],
intro H, exact H
end
definition actm_perm (a : aT) : perm rT :=
perm.mk (actm D to a) (actm_inj D to a)
include Hdeceq_rT
-- the orbit of x under the action of A
definition orbit [reducible] (A : finset aT) (x : rT) := to x ' A
-- Definition amove to A x y := [set a in A | to x a == y].
definition amove [reducible] (A : finset aT) (x y : rT) := { a ∈ A | to x a = y}
-- definition afix (to : rT → aT → rT) (A : finset aT) := { x ∈ univ | orbit to A x = '{x} }
definition afix [reducible] (A : finset aT) := { x ∈ univ | A ⊆ {a ∈ univ | to x a = x} }
-- definition is_fixed_point to A x :=
-- stabilizer in S : all elements a of the domain D such that the action of a fixes all S
-- Definition astab S to := D :&: [set a | S \subset [set x | to x a == x]].
definition astab [reducible] (S : finset rT) := D ∩ { a ∈ univ | S ⊆ {x ∈ univ | to x a = x}}
definition astab_in [reducible] (G : finset aT) [is_finsubg G] (S : finset rT) := G ∩ astab D to S
-- (* 'N_A(S | to) == the global stabiliser of S : {set rT} in D :&: A. *)
-- Definition astabs S to := D :&: [set a | S \subset to^~ a @^-1: S].
-- Notation "''N' ( S | to )" := (astabs S to)
definition astabs [reducible] (S : finset rT) :=
D ∩ { a ∈ univ | S ⊆ {(x : rT) ∈ univ | to x a ∈ S}}
-- Definition acts_on A S to := {in A, forall a x, (to x a \in S) = (x \in S)}.
-- this corresponds to {acts A, on S | to} == A acts on the set S (Prop statement).
definition acts_on_prop [reducible] (A : finset aT) (S : finset rT) :=
∀ a s, a ∈ A → s ∈ S → (to s a ∈ S ↔ s ∈ S)
definition acts_on [reducible] (A : finset aT) (S : finset rT) :=
A ⊆ astabs D to S
-- Definition atrans A S to := S \in orbit to A @: S.
definition atrans [reducible] (A : finset aT) (S : finset rT) := S ∈ orbit D to A ' S
definition faithful [reducible] (A : finset aT) (S : finset rT) :=
A ∩ astab D to S ⊆ '{1}
-- Notation "[ 'acts' A , 'on' S | to ]" := (A \subset pred_of_set 'N(S | to))
-- a few lemma to make proofs easier
lemma amove_of_to {A x y a} : a ∈ A → to x a = y → a ∈ amove D to A x y :=
assume HaA Hto, mem_sep_of_mem HaA Hto
lemma to_of_amove {A x y a} : a ∈ A → a ∈ amove D to A x y → to x a = y :=
assume HaA Hamove,
of_mem_sep Hamove
lemma astab_of_mem (S : finset rT) (g : aT) : g ∈ D → (∀ s, s ∈ S → to s g = s) → g ∈ astab D to S := take HgD HSg,
begin
apply (mem_inter HgD),
apply mem_sep_of_mem !mem_univ,
apply subset_of_forall,
intro s HsS, apply mem_sep_of_mem !mem_univ,
apply HSg s HsS
end
end defs
section rawaction
include Hdeceq_aT
variables (to : rT → aT → rT) (D : finset aT) [Hact_to : is_action D to]
lemma act_inj : left_injective to := and.left Hact_to
lemma actMin (x : rT) : act_morph D to x := and.right Hact_to x
include Hact_to
lemma actmEfun (a : aT) : a ∈ D -> actm D to a = λ x, to x a := take Ha, by rewrite [↑actm,(if_pos Ha)]
-- lemma act_morph_comp (a b : aT) : a ∈ D → b ∈ D → actm D to b ∘ actm D to a = actm D to (a * b) :=
-- take Ha Hb,
-- begin
-- rewrite (actmEfun to D a Ha),
-- rewrite (actmEfun to D b Hb),
-- apply funext, intro x,
-- rewrite ↑comp,
-- rewrite -(and.right Hact_to x a b Ha Hb),
-- end
-- omit Hact_to
include Hdeceq_rT
-- Lemma card_setact S a : #|to^* S a| = #|S|.
lemma card_setact S (a : aT) : card (actm D to a ' S) = card S :=
begin
apply card_image_eq_of_inj_on,
intro x1 x2 Hx1S Hx2S,
apply actm_inj
end
-- Lemma setact_is_action : is_action D to^*.
lemma setact_is_action : is_action D (λ (S : finset rT) (a : aT) , (λ s, to s a) ' S) := and.intro (take y,
begin
apply injective_image,
apply (and.left Hact_to),
end)
(take S, take a b Ha Hb,
begin
rewrite -image_comp,
apply eq_im_of_eq_f,
apply funext,
intro x,
rewrite [↑comp,-((and.right Hact_to) x a b Ha Hb)],
end)
-- Lemma orbitP A x y :
-- reflect (exists2 a, a \in A & to x a = y) (y \in orbit to A x).
-- Proof. by apply: (iffP imsetP) => [] [a]; exists a. Qed.
lemma orbitP A (x y : rT) :
y ∈ orbit D to A x ↔ exists a, a ∈ A ∧ to x a = y :=
iff.intro
(take Hyorbit,
begin
rewrite ↑orbit at Hyorbit,
rewrite mem_image_iff at Hyorbit,
exact Hyorbit
end)
(take Him,
begin
rewrite [↑orbit,mem_image_iff],
exact Him
end)
lemma mem_orbit (A : finset aT) (x : rT) (a : aT) : a ∈ A → to x a ∈ orbit D to A x := assume Ha, mem_image Ha rfl
lemma afixP (A : finset aT) (x : rT) : (∀ a, a ∈ A → to x a = x) ↔ x ∈ afix D to A :=
begin
rewrite ↑afix,
apply iff.intro,
intro HA,
apply (mem_sep_of_mem (mem_univ x)),
apply subset_of_forall,
intro a Ha,
apply (mem_sep_of_mem (mem_univ a)),
apply HA,
exact Ha,
intro Hx,
rewrite mem_sep_iff at Hx,
cases Hx with Hxuniv HxA,
intro a Ha,
have Ha1 : a ∈ {a ∈ univ | to x a = x}, from mem_of_subset_of_mem HxA Ha,
rewrite mem_sep_iff at Ha1,
exact (and.right Ha1)
end
-- Lemma afixS A B : A \subset B -> 'Fix_to(B) \subset 'Fix_to(A).
lemma afixS (A B : finset aT) : A ⊆ B → afix D to B ⊆ afix D to A :=
assume sAB,
begin
rewrite ↑afix,
rewrite subset_sep_iff,
intro x HBx,
apply subset_of_forall,
intro a Ha,
apply mem_sep_of_mem (mem_univ _),
apply (of_mem_sep (mem_of_subset_of_mem (subset.trans sAB HBx) Ha))
end
-- Lemma afixU A B : 'Fix_to(A :|: B) = 'Fix_to(A) :&: 'Fix_to(B).
lemma afixU (A B : finset aT) : afix D to (A ∩ B) = afix D to A ∩ afix D to B := sorry
-- Lemma afix1P a x : reflect (to x a = x) (x \in 'Fix_to[a]).
lemma afix1P (a : aT) (x : rT) : to x a = x ↔ x ∈ afix D to '{a} :=
iff.intro (assume Hxfix, mem_sep_of_mem (mem_univ _)
(begin
have ∀ b, b ∈ '{a} → b ∈ {a ∈ univ | to x a = x}, from take b Hb,
begin
apply mem_sep_of_mem (mem_univ _),
rewrite mem_singleton_iff at Hb,
rewrite Hb, exact Hxfix
end,
apply subset_of_forall this,
end)) (take Hxfix,
begin
have H : '{a} ⊆ {a ∈ univ | to x a = x}, from of_mem_sep Hxfix,
rewrite singleton_subset_iff at H,
apply of_mem_sep H
end)
-- Lemma astabIdom S : 'C_D(S | to) = 'C(S | to).
lemma astabIdom (S : finset rT) : D ∩ astab D to S = astab D to S :=
begin
rewrite ↑astab,
rewrite -inter_assoc,
rewrite inter_self,
end
-- Lemma astab_dom S : {subset 'C(S | to) <= D}.
lemma astab_dom (S : finset rT) : astab D to S ⊆ D := finset_inter_subset_left
-- Lemma astab_act S a x : a \in 'C(S | to) -> x \in S -> to x a = x.
lemma astab_act (S : finset rT) (a : aT) (x : rT) : a ∈ astab D to S → x ∈ S → to x a = x :=
begin
intro Ha Hx,
rewrite mem_inter_iff at Ha,
cases Ha with HaD Hasep,
have HSx : S ⊆ {x ∈ univ | to x a = x}, from of_mem_sep Hasep,
apply of_mem_sep (mem_of_subset_of_mem HSx Hx),
end
-- Lemma astabS S1 S2 : S1 \subset S2 -> 'C(S2 | to) \subset 'C(S1 | to).
lemma astabS (S1 S2 : finset rT) : S1 ⊆ S2 → astab D to S2 ⊆ astab D to S1 :=
assume s12,
subset_of_forall
(take a Ha,
mem_inter
(mem_of_subset_of_mem (astab_dom to D S2) Ha)
(mem_sep_of_mem !mem_univ (subset_of_forall (take x HxS1, (mem_sep_of_mem !mem_univ (astab_act to D S2 a x Ha (mem_of_subset_of_mem s12 HxS1)))))))
-- Lemma astabsIdom S : 'N_D(S | to) = 'N(S | to).
lemma astabsIdom (S : finset rT) : D ∩ astabs D to S ⊆ astabs D to S :=
finset_inter_subset_right
-- Lemma astabs_dom S : {subset 'N(S | to) <= D}.
lemma astabs_dom (S : finset rT) : astabs D to S ⊆ D :=
finset_inter_subset_left
-- Lemma astabs_act S a x : a \in 'N(S | to) -> (to x a \in S) = (x \in S).
lemma astabs_act (S : finset rT) (a : aT) (x : rT) : a ∈ astabs D to S → (to x a ∈ S ↔ x ∈ S) :=
assume Ha,
begin
rewrite ↑astabs at Ha,
rewrite mem_inter_iff at Ha,
cases Ha with HaD HS,
have HS1 : S ⊆ { x ∈ univ | to x a ∈ S}, from of_mem_sep HS,
have hsImS : image (λ x, to x a) { x ∈ univ | to x a ∈ S} ⊆ S, from
subset_of_forall
(take x Hx,
begin
rewrite mem_image_iff at Hx,
cases Hx with x1 Hx1,
cases Hx1 with Hx1 Hx1ax,
rewrite -Hx1ax, apply of_mem_sep Hx1
end),
have HeqCard1 : card (image (λ x, to x a) { x ∈ univ | to x a ∈ S}) = card { x ∈ univ | to x a ∈ S}, from
card_image_eq_of_inj_on (take u v Hu Hv, begin apply act_inj to D a end),
have card (image (λ x, to x a) { x ∈ univ | to x a ∈ S}) ≤ card S, from
card_le_card_of_subset hsImS,
have HleCard1 : card { x ∈ univ | to x a ∈ S} ≤ card S, from
eq.subst HeqCard1 this,
have HleCard2 : card { x ∈ univ | to x a ∈ S} ≥ card S, from
card_le_card_of_subset HS1,
have card { x ∈ univ | to x a ∈ S} = card S, from eq_of_le_of_ge HleCard1 HleCard2,
have HeqStoS : S = { x ∈ univ | to x a ∈ S}, from sorry, -- there should be a lemma to deduce this, this is easy!! TODO
apply iff.intro,
intro HxaS,
rewrite HeqStoS,
apply (mem_sep_of_mem !mem_univ),
exact HxaS,
intro HxS, apply of_mem_sep (eq.subst HeqStoS HxS),
end
-- Lemma astab_sub S : 'C(S | to) \subset 'N(S | to).
lemma astab_sub (S : finset rT) : astab D to S ⊆ astabs D to S :=
subset_of_forall (take a Ha,
mem_inter (mem_of_subset_of_mem (astab_dom to D S) Ha) (mem_sep_of_mem !mem_univ
begin
apply subset_of_forall,
intro x HxS,
apply mem_sep_of_mem,
apply !mem_univ,
rewrite (astab_act to D S a x Ha HxS),
exact HxS
end
))
-- Lemma astabsC S : 'N(~: S | to) = 'N(S | to).
-- Lemma astabsI S T : 'N(S | to) :&: 'N(T | to) \subset 'N(S :&: T | to).
-- Lemma astabs_setact S a : a \in 'N(S | to) -> to^* S a = S.
-- Lemma astab1_set S : 'C[S | set_action] = 'N(S | to).
-- Lemma astabs_set1 x : 'N([set x] | to) = 'C[x | to].
-- Lemma acts_dom A S : [acts A, on S | to] -> A \subset D.
lemma acts_dom (A : finset aT) (S : finset rT) : acts_on D to A S → A ⊆ D :=
take Hacts, subset.trans Hacts !finset_inter_subset_left
-- Lemma acts_act A S : [acts A, on S | to] -> {acts A, on S | to}.
lemma acts_act (A : finset aT) (S : finset rT) : acts_on D to A S → acts_on_prop D to A S :=
assume Hacts_on,
begin intros a x Ha Hx,
have a ∈ astabs D to S ,
from mem_of_subset_of_mem Hacts_on Ha,
exact (astabs_act to D S a x this)
end
-- mem_inter (mem_of_subset_of_mem (astab_dom to D S) Ha) (mem_sep_of_mem !mem_univ
-- begin
-- have _, from astabs_act
-- end))
end rawaction
section partial_action
variables (to : rT → aT → rT) (D : finset aT) [Hact_to : is_action D to]
variable [HsubgD : is_finsubg D]
include Hdeceq_rT
include HsubgD Hact_to
lemma act1 (x : rT) : to x 1 = x :=
begin
apply (act_inj to D 1),
have 1 ∈ D, from finsubg_has_one D,
rewrite -(actMin to D x 1 1 this this),
rewrite one_mul,
end
lemma actKin (x : rT) (a : aT) : a ∈ D → to (to x a) a⁻¹ = x :=
assume HaD,
begin
rewrite -(actMin to D x a a⁻¹ HaD (finsubg_has_inv D HaD)),
have a * a⁻¹ = 1, from sorry, -- can't find this!!!!
rewrite this,
apply (act1 to D x)
end
lemma actKVin (x : rT) (a : aT) : a ∈ D → to (to x a⁻¹) a = x :=
assume HaD,
begin
rewrite -(inv_inv a) at {2},
rewrite (actKin to D x (a⁻¹) (finsubg_has_inv D HaD)),
end
lemma orbit_refl G [is_finsubg G] (x : rT) : x ∈ orbit D to G x :=
begin
-- rewrite -(act1 to D),
have to x 1 ∈ orbit D to G x, from (mem_orbit to D G x 1 (finsubg_has_one G)),
exact (eq.subst (act1 to D x) this)
end
-- Lemma orbit_in_sym G : G \subset D -> symmetric (orbit_rel G).
definition orbit_rel A := λ x y, x ∈ orbit D to A y
lemma orbit_in_sym (G : finset aT) [is_finsubg G] : G ⊆ D → symmetric (orbit_rel to D G) := assume sGD, take x y, assume Hxy,
begin
rewrite ↑orbit_rel at Hxy,
rewrite (orbitP to D) at Hxy,
rewrite [↑orbit_rel,orbitP to D],
cases Hxy with g Hg,
cases Hg with HgG Hgyx,
apply (exists.intro g⁻¹),
apply and.intro,
apply (finsubg_has_inv G HgG),
rewrite -Hgyx,
rewrite (actKin to D y g (mem_of_subset_of_mem sGD HgG))
end
-- Lemma orbit_in_trans G : G \subset D -> transitive (orbit_rel G).
lemma orbit_in_trans (G : finset aT) [is_finsubg G]: G ⊆ D → transitive (orbit_rel to D G) := assume sGD,
begin
intro x y z Hxy Hyz,
rewrite ↑orbit_rel at Hxy,
rewrite ↑orbit_rel at Hyz,
rewrite (orbitP to D) at Hxy,
rewrite (orbitP to D) at Hyz,
cases Hxy with g Hg,
cases Hg with HgG Hgyx,
cases Hyz with g1 Hg1,
cases Hg1 with Hg1G Hg1yz,
rewrite [↑orbit_rel,orbitP to D],
apply (exists.intro (g1 * g)),
apply and.intro,
apply (finsubg_mul_closed _ Hg1G HgG),
rewrite [-Hgyx,-Hg1yz],
rewrite (actMin to D z g1 g (mem_of_subset_of_mem sGD Hg1G) (mem_of_subset_of_mem sGD HgG)),
end
-- Lemma orbit_in_eqP G x y :
-- G \subset D -> reflect (orbit to G x = orbit to G y) (x \in orbit to G y).
lemma orbit_in_eqP (G : finset aT) [is_finsubg G] (x y : rT) :
G ⊆ D →
((orbit D to G x = orbit D to G y) ↔ (x ∈ orbit D to G y)) :=
begin
intro sGD,
apply iff.intro,
intro Heq, rewrite -Heq, apply (orbit_refl to D G),
intro Hxorby,
apply ext,
intro a,
apply iff.intro,
intro Hax,
apply (orbit_in_trans to D G sGD Hax Hxorby),
intro Hay,
apply (orbit_in_sym to D G sGD),
apply (orbit_in_trans to D G sGD),
apply Hxorby,
apply (orbit_in_sym to D G sGD),
apply Hay
end
-- -- this is the wrong kind of partition, on the whole type
-- -- this lemma is pretty much useless
-- lemma orbit_is_partition (G : finset aT) [is_finsubg G] (S : finset rT) :
-- acts_on D to G S → is_partition (orbit D to D) :=
-- assume Hacts_on,
-- have sGD : G ⊆ D, from acts_dom to D G S Hacts_on,
-- begin
-- intro a b,
-- apply classical.eq.of_iff,
-- apply iff.intro,
-- rewrite (orbit_in_eqP to D D a b !subset.refl),
-- intro H, exact H,
-- intro H,
-- rewrite -(orbit_in_eqP to D D a b !subset.refl),
-- exact H
-- end
lemma orbit_is_partition (G : finset aT) [is_finsubg G] (S : finset rT) :
acts_on D to G S → is_partition (orbit D to G) :=
assume Hacts_on,
have sGD : G ⊆ D, from acts_dom to D G S Hacts_on,
begin
intro a b,
apply classical.eq.of_iff,
apply iff.intro,
rewrite (orbit_in_eqP to D G a b sGD),
intro H, exact H,
intro H,
rewrite -(orbit_in_eqP to D G a b sGD),
exact H
end
-- same here
definition orbit_partition_univ (G : finset aT) [is_finsubg G] (S : finset rT) (Hacts_on : acts_on D to G S) : @partition rT _ :=
partition.mk univ (orbit D to G) (orbit_is_partition to D G S Hacts_on)
(partition.restriction_imp_union (orbit D to G)
(orbit_is_partition to D G S Hacts_on)
(λ a Pa, !subset_univ))
definition orbit_partition (G : finset aT) [is_finsubg G] (S : finset rT) (Hacts_on : acts_on D to G S) : @partition rT _ :=
partition.mk S (orbit D to G) (orbit_is_partition to D G S Hacts_on)
(partition.restriction_imp_union (orbit D to G)
(orbit_is_partition to D G S Hacts_on)
(λ a Pa,
begin
rewrite ↑acts_on at Hacts_on, -- check_expr (astabs_act to D S),
apply subset_of_forall,
intro x Hx, rewrite orbitP at Hx,
cases Hx with g Hg,
cases Hg with HgG Hagx,
rewrite -Hagx,
rewrite (astabs_act to D S g a (mem_of_subset_of_mem Hacts_on HgG)),
exact Pa
end))
definition orbits (G : finset aT) [is_finsubg G] (S : finset rT) (Hacts_on : acts_on D to G S) : finset (finset rT) := partition.equiv_classes (orbit_partition to D G S Hacts_on)
set_option formatter.hide_full_terms false
lemma orbit_class_equation (G : finset aT) [is_finsubg G] (S : finset rT) (Hacts_on : acts_on D to G S) :
card S = Sum (orbits to D G S Hacts_on) card :=
partition.class_equation (orbit_partition to D G S Hacts_on)
end partial_action
section orbit_stabilizer
variables (to : rT → aT → rT) (D : finset aT) [Hact_to : is_action D to] [groupD : is_finsubg D]
-- variables (D : finset aT) [groupD : is_finsubg D]
variables (G : finset aT) [groupG : is_finsubg G]
variable x : rT
variable (sGD : G ⊆ D)
include sGD
include Hdeceq_rT
include Hdeceq_aT
include Hact_to
include groupG
include groupD
-- Lemma amove_act a : a \in G -> amove to G x (to x a) = 'C_G[x | to] :* a.
lemma amove_act (a : aT) : a ∈ G → amove D to G x (to x a) = fin_rcoset (astab_in D to G '{x}) a := take HaG,
begin
apply ext,
intro b,
apply iff.intro,
intro Hbx,
rewrite [↑fin_rcoset,mem_image_iff],
rewrite mem_sep_iff at Hbx,
apply (exists.intro (b * a⁻¹)),
apply and.intro,
have invaG : a⁻¹ ∈ G, from finsubg_has_inv G HaG,
have HbinvaG : (b * a⁻¹) ∈ G, from (finsubg_mul_closed _ (and.left Hbx) invaG),
apply mem_inter,
exact HbinvaG,
apply (mem_inter (mem_of_subset_of_mem sGD HbinvaG)),
apply (mem_sep_of_mem !mem_univ),
rewrite singleton_subset_iff,
apply (mem_sep_of_mem !mem_univ),
rewrite (actMin to D x b a⁻¹ (mem_of_subset_of_mem sGD (and.left Hbx)) (mem_of_subset_of_mem sGD invaG)),
rewrite (and.right Hbx),
rewrite -(actMin to D x a a⁻¹ (mem_of_subset_of_mem sGD HaG) (mem_of_subset_of_mem sGD invaG)),
have Hobvious : a * a⁻¹ = 1, from sorry, -- still can't find this lemma
rewrite Hobvious,
apply (act1 to D x),
rewrite ↑rmul_by,
-- rewrite -(inv_inv a),
have Hobvious1 : a⁻¹ * a = 1, from sorry,
rewrite [!mul.assoc,Hobvious1],
rewrite mul_one,
intro Hb,
rewrite ↑fin_rcoset at Hb,
rewrite mem_image_iff at Hb,
cases Hb with g Hg,
cases Hg with HgGastab Hagb,
rewrite mem_inter_eq at HgGastab,
apply amove_of_to,
rewrite [-Hagb,↑rmul_by],
apply (finsubg_mul_closed G ),
exact and.left HgGastab,
exact HaG,
rewrite [-Hagb,↑rmul_by],
rewrite (actMin to D x g a (mem_of_subset_of_mem sGD (and.left HgGastab)) (mem_of_subset_of_mem sGD HaG)),
rewrite (astab_act to D '{x} g x (and.right HgGastab) (mem_singleton x)),
end
lemma amove_orbit : (amove D to G x) ' (orbit D to G x) = fin_rcosets (astab_in D to G '{x}) (G : finset aT) :=
ext (take S,
begin
apply iff.intro,
intro HSmove_orbit,
rewrite mem_image_iff at HSmove_orbit,
cases HSmove_orbit with y Hy,
cases Hy with Horbit Hamove,
rewrite orbitP at Horbit,
cases Horbit with g HgG,
cases HgG with HgG Hgxy,
rewrite -Hgxy at Hamove,
rewrite (amove_act to D G x sGD g HgG) at Hamove,
rewrite -Hamove,
apply mem_image HgG rfl,
intro Hrcosets,
rewrite mem_image_iff at Hrcosets,
cases Hrcosets with g Hg,
cases Hg with HgG Hgrcoset,
rewrite -(amove_act to D G x sGD g HgG) at Hgrcoset,
rewrite -Hgrcoset,
have Hmemorbit : to x g ∈ orbit D to G x, from mem_image HgG rfl,
apply mem_image Hmemorbit,
apply rfl
end)
-- -- Lemma amove_orbit : amove to G x @: orbit to G x = rcosets 'C_G[x | to] G.
-- lemma amove_orbit : amove D to G x ' (orbit D to G) = fin_rcosets (G ∩ astab D to '{x}) G := sorry
lemma astab_has_one (S : finset rT) : 1 ∈ astab D to S :=
mem_inter (!finsubg_has_one)
(mem_sep_of_mem !mem_univ (subset_of_forall (take s Hs, mem_sep_of_mem !mem_univ (act1 to D s))))
lemma astab_mul_closed (S : finset rT) : finset_mul_closed_on (astab D to S) :=
take x y Hx Hy,
begin
have Hx1 : ∀ s, s ∈ S → to s x = s, from take s, astab_act to D S x s Hx,
have Hy1 : ∀ s, s ∈ S → to s y = s, from take s, astab_act to D S y s Hy,
rewrite mem_inter_eq at Hx,
rewrite mem_inter_eq at Hy,
cases Hx with HxD Hx,
cases Hy with HyD Hy,
rewrite mem_inter_iff,
apply and.intro,
apply finsubg_mul_closed D HxD HyD,
apply mem_sep_of_mem !mem_univ,
apply subset_of_forall,
intro s HsS, apply mem_sep_of_mem !mem_univ,
rewrite (actMin to D s x y HxD HyD),
rewrite (Hx1 s HsS),
rewrite (Hy1 s HsS)
end
lemma astab_has_inv (S : finset rT) : finset_has_inv (astab D to S) :=
take g Hg, astab_of_mem D to S g⁻¹ (finsubg_has_inv D (mem_of_mem_inter_left Hg)) (take s HsS, have Hgs : to s g = s, from astab_act to D S _ _ Hg HsS,
begin
rewrite -Hgs at {1},
rewrite -(actMin to D s g g⁻¹ (mem_of_mem_inter_left Hg) (finsubg_has_inv D (mem_of_mem_inter_left Hg))),
have Hobvious : g * g⁻¹ = 1, from sorry, -- TODO
rewrite Hobvious,
apply act1 to D
end)
definition astab_is_finsubg [instance] (S : finset rT) :
is_finsubg (astab D to S) := is_finsubg.mk (astab_has_one to D G sGD S) (astab_mul_closed to D G sGD S) (astab_has_inv to D G sGD S)
definition inter_is_finsubg [instance] {G1 : finset aT} {G2 : finset aT} [group_G1 : is_finsubg G1] [group_G2 : is_finsubg G2] : is_finsubg (G1 ∩ G2) := sorry
lemma stab_subset (S : finset rT ) : G ∩ astab D to S ⊆ D :=
begin
apply (subset.trans finset_inter_subset_left sGD),
end
lemma amove_inj (a : rT) : set.inj_on (amove D to G a) (ts (orbit D to G a)) :=
begin
intro x y Hx Hy Heq,
rewrite -mem_eq_mem_to_set at Hx,
rewrite -mem_eq_mem_to_set at Hy,
rewrite orbitP at Hx,
rewrite orbitP at Hy,
cases Hx with gx Hgx,
cases Hgx with HgxG Hgxax,
cases Hy with gy Hgy,
cases Hgy with HgyG Hgyay,
have Hgxamove : gx ∈ amove D to G a x, from amove_of_to D to HgxG Hgxax,
rewrite Heq at Hgxamove,
have to a gx = y, from to_of_amove D to HgxG Hgxamove,
rewrite [-Hgxax,-this]
end
theorem orbit_stabilizer_theorem (a : rT) : card G = card (orbit D to G a) * card (G ∩ astab D to '{a}) :=
have finsubg_astab : is_finsubg (astab D to '{a}), from astab_is_finsubg to D G sGD _,
have finsubg_inter : is_finsubg (astab_in D to G '{a}), from inter_is_finsubg to D G sGD,
calc card G = card (fin_lcosets (astab_in D to G '{a}) G) * card (G ∩ astab D to '{a}) :
lagrange_theorem (!finset_inter_subset_left)
... = card (fin_rcosets (astab_in D to G '{a}) G) * card (G ∩ astab D to '{a}) :
begin rewrite (card_rcosets_eq_card_lcosets (astab_in D to G '{a}) G) end
... = card ((amove D to G a) ' (orbit D to G a)) * card (G ∩ astab D to '{a}) : begin rewrite -(amove_orbit to D G a sGD) end
... = card ((orbit D to G a)) * card (G ∩ astab D to '{a}) : begin rewrite (card_image_eq_of_inj_on (amove_inj to D G sGD a)) end
end orbit_stabilizer
end partial_actions
|
55e9c16f6644d55e62ab2d80cb4eca7a2a4ade05 | 57c233acf9386e610d99ed20ef139c5f97504ba3 | /src/linear_algebra/matrix/nonsingular_inverse.lean | 1e48da0ed835ad01a133dd657da7fd9951a26472 | [
"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 | 15,126 | lean | /-
Copyright (c) 2019 Tim Baanen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Tim Baanen, Lu-Ming Zhang
-/
import algebra.regular.smul
import linear_algebra.matrix.adjugate
import linear_algebra.matrix.polynomial
/-!
# Nonsingular inverses
In this file, we define an inverse for square matrices of invertible determinant.
For matrices that are not square or not of full rank, there is a more general notion of
pseudoinverses which we do not consider here.
The definition of inverse used in this file is the adjugate divided by the determinant.
We show that dividing the adjugate by `det A` (if possible), giving a matrix `A⁻¹` (`nonsing_inv`),
will result in a multiplicative inverse to `A`.
Note that there are at least three different inverses in mathlib:
* `A⁻¹` (`has_inv.inv`): alone, this satisfies no properties, although it is usually used in
conjunction with `group` or `group_with_zero`. On matrices, this is defined to be zero when no
inverse exists.
* `⅟A` (`inv_of`): this is only available in the presence of `[invertible A]`, which guarantees an
inverse exists.
* `ring.inverse A`: this is defined on any `monoid_with_zero`, and just like `⁻¹` on matrices, is
defined to be zero when no inverse exists.
We start by working with `invertible`, and show the main results:
* `matrix.invertible_of_det_invertible`
* `matrix.det_invertible_of_invertible`
* `matrix.is_unit_iff_is_unit_det`
* `matrix.mul_eq_one_comm`
After this we define `matrix.has_inv` and show it matches `⅟A` and `ring.inverse A`.
The rest of the results in the file are then about `A⁻¹`
## References
* https://en.wikipedia.org/wiki/Cramer's_rule#Finding_inverse_matrix
## Tags
matrix inverse, cramer, cramer's rule, adjugate
-/
namespace matrix
universes u v
variables {n : Type u} [decidable_eq n] [fintype n] {α : Type v} [comm_ring α]
open_locale matrix big_operators
open equiv equiv.perm finset
variables (A : matrix n n α) (B : matrix n n α)
/-! ### Matrices are `invertible` iff their determinants are -/
section invertible
/-- A copy of `inv_of_mul_self` using `⬝` not `*`. -/
protected lemma inv_of_mul_self [invertible A] : ⅟A ⬝ A = 1 := inv_of_mul_self A
/-- A copy of `mul_inv_of_self` using `⬝` not `*`. -/
protected lemma mul_inv_of_self [invertible A] : A ⬝ ⅟A = 1 := mul_inv_of_self A
/-- If `A.det` has a constructive inverse, produce one for `A`. -/
def invertible_of_det_invertible [invertible A.det] : invertible A :=
{ inv_of := ⅟A.det • A.adjugate,
mul_inv_of_self :=
by rw [mul_smul_comm, matrix.mul_eq_mul, mul_adjugate, smul_smul, inv_of_mul_self, one_smul],
inv_of_mul_self :=
by rw [smul_mul_assoc, matrix.mul_eq_mul, adjugate_mul, smul_smul, inv_of_mul_self, one_smul] }
lemma inv_of_eq [invertible A.det] [invertible A] : ⅟A = ⅟A.det • A.adjugate :=
by { letI := invertible_of_det_invertible A, convert (rfl : ⅟A = _) }
/-- `A.det` is invertible if `A` has a left inverse. -/
def det_invertible_of_left_inverse (h : B ⬝ A = 1) : invertible A.det :=
{ inv_of := B.det,
mul_inv_of_self := by rw [mul_comm, ← det_mul, h, det_one],
inv_of_mul_self := by rw [← det_mul, h, det_one] }
/-- `A.det` is invertible if `A` has a right inverse. -/
def det_invertible_of_right_inverse (h : A ⬝ B = 1) : invertible A.det :=
{ inv_of := B.det,
mul_inv_of_self := by rw [← det_mul, h, det_one],
inv_of_mul_self := by rw [mul_comm, ← det_mul, h, det_one] }
/-- If `A` has a constructive inverse, produce one for `A.det`. -/
def det_invertible_of_invertible [invertible A] : invertible A.det :=
det_invertible_of_left_inverse A (⅟A) (inv_of_mul_self _)
lemma det_inv_of [invertible A] [invertible A.det] : (⅟A).det = ⅟A.det :=
by { letI := det_invertible_of_invertible A, convert (rfl : _ = ⅟A.det) }
/-- Together `matrix.det_invertible_of_invertible` and `matrix.invertible_of_det_invertible` form an
equivalence, although both sides of the equiv are subsingleton anyway. -/
@[simps]
def invertible_equiv_det_invertible : invertible A ≃ invertible A.det :=
{ to_fun := @det_invertible_of_invertible _ _ _ _ _ A,
inv_fun := @invertible_of_det_invertible _ _ _ _ _ A,
left_inv := λ _, subsingleton.elim _ _,
right_inv := λ _, subsingleton.elim _ _ }
variables {A B}
lemma mul_eq_one_comm : A ⬝ B = 1 ↔ B ⬝ A = 1 :=
suffices ∀ A B, A ⬝ B = 1 → B ⬝ A = 1, from ⟨this A B, this B A⟩, assume A B h,
begin
letI : invertible B.det := det_invertible_of_left_inverse _ _ h,
letI : invertible B := invertible_of_det_invertible B,
calc B ⬝ A = (B ⬝ A) ⬝ (B ⬝ ⅟B) : by rw [matrix.mul_inv_of_self, matrix.mul_one]
... = B ⬝ ((A ⬝ B) ⬝ ⅟B) : by simp only [matrix.mul_assoc]
... = B ⬝ ⅟B : by rw [h, matrix.one_mul]
... = 1 : matrix.mul_inv_of_self B,
end
variables (A B)
/-- We can construct an instance of invertible A if A has a left inverse. -/
def invertible_of_left_inverse (h : B ⬝ A = 1) : invertible A :=
⟨B, h, mul_eq_one_comm.mp h⟩
/-- We can construct an instance of invertible A if A has a right inverse. -/
def invertible_of_right_inverse (h : A ⬝ B = 1) : invertible A :=
⟨B, mul_eq_one_comm.mp h, h⟩
/-- Given a proof that `A.det` has a constructive inverse, lift `A` to `(matrix n n α)ˣ`-/
def unit_of_det_invertible [invertible A.det] : (matrix n n α)ˣ :=
@unit_of_invertible _ _ A (invertible_of_det_invertible A)
/-- When lowered to a prop, `matrix.invertible_equiv_det_invertible` forms an `iff`. -/
lemma is_unit_iff_is_unit_det : is_unit A ↔ is_unit A.det :=
begin
split; rintros ⟨x, hx⟩; refine @is_unit_of_invertible _ _ _ (id _),
{ haveI : invertible A := hx.rec x.invertible,
apply det_invertible_of_invertible, },
{ haveI : invertible A.det := hx.rec x.invertible,
apply invertible_of_det_invertible, },
end
/-! #### Variants of the statements above with `is_unit`-/
lemma is_unit_det_of_invertible [invertible A] : is_unit A.det :=
@is_unit_of_invertible _ _ _ (det_invertible_of_invertible A)
variables {A B}
lemma is_unit_det_of_left_inverse (h : B ⬝ A = 1) : is_unit A.det :=
@is_unit_of_invertible _ _ _ (det_invertible_of_left_inverse _ _ h)
lemma is_unit_det_of_right_inverse (h : A ⬝ B = 1) : is_unit A.det :=
@is_unit_of_invertible _ _ _ (det_invertible_of_right_inverse _ _ h)
lemma det_ne_zero_of_left_inverse [nontrivial α] (h : B ⬝ A = 1) : A.det ≠ 0 :=
(is_unit_det_of_left_inverse h).ne_zero
lemma det_ne_zero_of_right_inverse [nontrivial α] (h : A ⬝ B = 1) : A.det ≠ 0 :=
(is_unit_det_of_right_inverse h).ne_zero
end invertible
open_locale classical
lemma is_unit_det_transpose (h : is_unit A.det) : is_unit Aᵀ.det :=
by { rw det_transpose, exact h, }
/-! ### A noncomputable `has_inv` instance -/
/-- The inverse of a square matrix, when it is invertible (and zero otherwise).-/
noncomputable instance : has_inv (matrix n n α) := ⟨λ A, ring.inverse A.det • A.adjugate⟩
lemma inv_def (A : matrix n n α) : A⁻¹ = ring.inverse A.det • A.adjugate := rfl
lemma nonsing_inv_apply_not_is_unit (h : ¬ is_unit A.det) :
A⁻¹ = 0 :=
by rw [inv_def, ring.inverse_non_unit _ h, zero_smul]
lemma nonsing_inv_apply (h : is_unit A.det) :
A⁻¹ = (↑h.unit⁻¹ : α) • A.adjugate :=
by rw [inv_def, ←ring.inverse_unit h.unit, is_unit.unit_spec]
/-- The nonsingular inverse is the same as `inv_of` when `A` is invertible. -/
@[simp] lemma inv_of_eq_nonsing_inv [invertible A] : ⅟A = A⁻¹ :=
begin
letI := det_invertible_of_invertible A,
rw [inv_def, ring.inverse_invertible, inv_of_eq],
end
/-- The nonsingular inverse is the same as the general `ring.inverse`. -/
lemma nonsing_inv_eq_ring_inverse : A⁻¹ = ring.inverse A :=
begin
by_cases h_det : is_unit A.det,
{ casesI (A.is_unit_iff_is_unit_det.mpr h_det).nonempty_invertible,
rw [←inv_of_eq_nonsing_inv, ring.inverse_invertible], },
{ have h := mt A.is_unit_iff_is_unit_det.mp h_det,
rw [ring.inverse_non_unit _ h, nonsing_inv_apply_not_is_unit A h_det], },
end
lemma transpose_nonsing_inv : (A⁻¹)ᵀ = (Aᵀ)⁻¹ :=
by rw [inv_def, inv_def, transpose_smul, det_transpose, adjugate_transpose]
lemma conj_transpose_nonsing_inv [star_ring α] : (A⁻¹)ᴴ = (Aᴴ)⁻¹ :=
by rw [inv_def, inv_def, conj_transpose_smul, det_conj_transpose, adjugate_conj_transpose,
ring.inverse_star]
/-- The `nonsing_inv` of `A` is a right inverse. -/
@[simp] lemma mul_nonsing_inv (h : is_unit A.det) : A ⬝ A⁻¹ = 1 :=
begin
casesI (A.is_unit_iff_is_unit_det.mpr h).nonempty_invertible,
rw [←inv_of_eq_nonsing_inv, matrix.mul_inv_of_self],
end
/-- The `nonsing_inv` of `A` is a left inverse. -/
@[simp] lemma nonsing_inv_mul (h : is_unit A.det) : A⁻¹ ⬝ A = 1 :=
begin
casesI (A.is_unit_iff_is_unit_det.mpr h).nonempty_invertible,
rw [←inv_of_eq_nonsing_inv, matrix.inv_of_mul_self],
end
@[simp] lemma mul_inv_of_invertible [invertible A] : A ⬝ A⁻¹ = 1 :=
mul_nonsing_inv A (is_unit_det_of_invertible A)
@[simp] lemma inv_mul_of_invertible [invertible A] : A⁻¹ ⬝ A = 1 :=
nonsing_inv_mul A (is_unit_det_of_invertible A)
lemma nonsing_inv_cancel_or_zero :
(A⁻¹ ⬝ A = 1 ∧ A ⬝ A⁻¹ = 1) ∨ A⁻¹ = 0 :=
begin
by_cases h : is_unit A.det,
{ exact or.inl ⟨nonsing_inv_mul _ h, mul_nonsing_inv _ h⟩ },
{ exact or.inr (nonsing_inv_apply_not_is_unit _ h) }
end
lemma det_nonsing_inv_mul_det (h : is_unit A.det) : A⁻¹.det * A.det = 1 :=
by rw [←det_mul, A.nonsing_inv_mul h, det_one]
@[simp] lemma det_nonsing_inv : A⁻¹.det = ring.inverse A.det :=
begin
by_cases h : is_unit A.det,
{ casesI h.nonempty_invertible, letI := invertible_of_det_invertible A,
rw [ring.inverse_invertible, ←inv_of_eq_nonsing_inv, det_inv_of] },
casesI is_empty_or_nonempty n,
{ rw [det_is_empty, det_is_empty, ring.inverse_one] },
{ rw [ring.inverse_non_unit _ h, nonsing_inv_apply_not_is_unit _ h, det_zero ‹_›] },
end
lemma is_unit_nonsing_inv_det (h : is_unit A.det) : is_unit A⁻¹.det :=
is_unit_of_mul_eq_one _ _ (A.det_nonsing_inv_mul_det h)
@[simp] lemma nonsing_inv_nonsing_inv (h : is_unit A.det) : (A⁻¹)⁻¹ = A :=
calc (A⁻¹)⁻¹ = 1 ⬝ (A⁻¹)⁻¹ : by rw matrix.one_mul
... = A ⬝ A⁻¹ ⬝ (A⁻¹)⁻¹ : by rw A.mul_nonsing_inv h
... = A : by { rw [matrix.mul_assoc,
(A⁻¹).mul_nonsing_inv (A.is_unit_nonsing_inv_det h),
matrix.mul_one], }
lemma is_unit_nonsing_inv_det_iff {A : matrix n n α} :
is_unit A⁻¹.det ↔ is_unit A.det :=
by rw [matrix.det_nonsing_inv, is_unit_ring_inverse]
/- `is_unit.invertible` lifts the proposition `is_unit A` to a constructive inverse of `A`. -/
/-- A version of `matrix.invertible_of_det_invertible` with the inverse defeq to `A⁻¹` that is
therefore noncomputable. -/
noncomputable def invertible_of_is_unit_det (h : is_unit A.det) : invertible A :=
⟨A⁻¹, nonsing_inv_mul A h, mul_nonsing_inv A h⟩
/-- A version of `matrix.units_of_det_invertible` with the inverse defeq to `A⁻¹` that is therefore
noncomputable. -/
noncomputable def nonsing_inv_unit (h : is_unit A.det) : (matrix n n α)ˣ :=
@unit_of_invertible _ _ _ (invertible_of_is_unit_det A h)
lemma unit_of_det_invertible_eq_nonsing_inv_unit [invertible A.det] :
unit_of_det_invertible A = nonsing_inv_unit A (is_unit_of_invertible _) :=
by { ext, refl }
variables {A} {B}
/-- If matrix A is left invertible, then its inverse equals its left inverse. -/
lemma inv_eq_left_inv (h : B ⬝ A = 1) : A⁻¹ = B :=
begin
letI := invertible_of_left_inverse _ _ h,
exact inv_of_eq_nonsing_inv A ▸ inv_of_eq_left_inv h,
end
/-- If matrix A is right invertible, then its inverse equals its right inverse. -/
lemma inv_eq_right_inv (h : A ⬝ B = 1) : A⁻¹ = B :=
inv_eq_left_inv (mul_eq_one_comm.2 h)
section inv_eq_inv
variables {C : matrix n n α}
/-- The left inverse of matrix A is unique when existing. -/
lemma left_inv_eq_left_inv (h : B ⬝ A = 1) (g : C ⬝ A = 1) : B = C :=
by rw [←inv_eq_left_inv h, ←inv_eq_left_inv g]
/-- The right inverse of matrix A is unique when existing. -/
lemma right_inv_eq_right_inv (h : A ⬝ B = 1) (g : A ⬝ C = 1) : B = C :=
by rw [←inv_eq_right_inv h, ←inv_eq_right_inv g]
/-- The right inverse of matrix A equals the left inverse of A when they exist. -/
lemma right_inv_eq_left_inv (h : A ⬝ B = 1) (g : C ⬝ A = 1) : B = C :=
by rw [←inv_eq_right_inv h, ←inv_eq_left_inv g]
lemma inv_inj (h : A⁻¹ = B⁻¹) (h' : is_unit A.det) : A = B :=
begin
refine left_inv_eq_left_inv (mul_nonsing_inv _ h') _,
rw h,
refine mul_nonsing_inv _ _,
rwa [←is_unit_nonsing_inv_det_iff, ←h, is_unit_nonsing_inv_det_iff]
end
end inv_eq_inv
variable (A)
@[simp] lemma inv_zero : (0 : matrix n n α)⁻¹ = 0 :=
begin
casesI (subsingleton_or_nontrivial α) with ht ht,
{ simp },
cases (fintype.card n).zero_le.eq_or_lt with hc hc,
{ rw [eq_comm, fintype.card_eq_zero_iff] at hc,
haveI := hc,
ext i,
exact (is_empty.false i).elim },
{ have hn : nonempty n := fintype.card_pos_iff.mp hc,
refine nonsing_inv_apply_not_is_unit _ _,
simp [hn] },
end
@[simp] lemma inv_one : (1 : matrix n n α)⁻¹ = 1 :=
inv_eq_left_inv (by simp)
lemma inv_smul (k : α) [invertible k] (h : is_unit A.det) : (k • A)⁻¹ = ⅟k • A⁻¹ :=
inv_eq_left_inv (by simp [h, smul_smul])
lemma inv_smul' (k : αˣ) (h : is_unit A.det) : (k • A)⁻¹ = k⁻¹ • A⁻¹ :=
inv_eq_left_inv (by simp [h, smul_smul])
lemma inv_adjugate (A : matrix n n α) (h : is_unit A.det) :
(adjugate A)⁻¹ = h.unit⁻¹ • A :=
begin
refine inv_eq_left_inv _,
rw [smul_mul, mul_adjugate, units.smul_def, smul_smul, h.coe_inv_mul, one_smul]
end
@[simp] lemma inv_inv_inv (A : matrix n n α) : A⁻¹⁻¹⁻¹ = A⁻¹ :=
begin
by_cases h : is_unit A.det,
{ rw [nonsing_inv_nonsing_inv _ h] },
{ simp [nonsing_inv_apply_not_is_unit _ h] }
end
lemma mul_inv_rev (A B : matrix n n α) : (A ⬝ B)⁻¹ = B⁻¹ ⬝ A⁻¹ :=
begin
simp only [inv_def],
rw [matrix.smul_mul, matrix.mul_smul, smul_smul, det_mul, adjugate_mul_distrib,
ring.mul_inverse_rev],
end
/-- One form of **Cramer's rule**. See `matrix.mul_vec_cramer` for a stronger form. -/
@[simp] lemma det_smul_inv_mul_vec_eq_cramer (A : matrix n n α) (b : n → α) (h : is_unit A.det) :
A.det • A⁻¹.mul_vec b = cramer A b :=
begin
rw [cramer_eq_adjugate_mul_vec, A.nonsing_inv_apply h, ← smul_mul_vec_assoc,
smul_smul, h.mul_coe_inv, one_smul]
end
/-- One form of **Cramer's rule**. See `matrix.mul_vec_cramer` for a stronger form. -/
@[simp] lemma det_smul_inv_vec_mul_eq_cramer_transpose
(A : matrix n n α) (b : n → α) (h : is_unit A.det) :
A.det • A⁻¹.vec_mul b = cramer Aᵀ b :=
by rw [← (A⁻¹).transpose_transpose, vec_mul_transpose, transpose_nonsing_inv, ← det_transpose,
Aᵀ.det_smul_inv_mul_vec_eq_cramer _ (is_unit_det_transpose A h)]
end matrix
|
2a8a2950f6ae27f3a29a720176a24baf5104030d | 96338d06deb5f54f351493a71d6ecf6c546089a2 | /priv/Lean/PackSet.lean | a4dd79ba45ce6944dd80217e7c8f7688590f2448 | [] | no_license | silky/exe | 5f9e4eea772d74852a1a2fac57d8d20588282d2b | e81690d6e16f2a83c105cce446011af6ae905b81 | refs/heads/master | 1,609,385,766,412 | 1,472,164,223,000 | 1,472,164,223,000 | 66,610,224 | 1 | 0 | null | 1,472,178,919,000 | 1,472,178,919,000 | null | UTF-8 | Lean | false | false | 49 | lean | -- Pack (X : SetoidCat) := Lim( ForgetUnder X )
|
b5e702e188e9aaf6de93d93b0d3558601f7e722c | 35677d2df3f081738fa6b08138e03ee36bc33cad | /src/tactic/omega/main.lean | ae3be76063ffd37b4ccac7ee08da45fdbf4a06bc | [
"Apache-2.0"
] | permissive | gebner/mathlib | eab0150cc4f79ec45d2016a8c21750244a2e7ff0 | cc6a6edc397c55118df62831e23bfbd6e6c6b4ab | refs/heads/master | 1,625,574,853,976 | 1,586,712,827,000 | 1,586,712,827,000 | 99,101,412 | 1 | 0 | Apache-2.0 | 1,586,716,389,000 | 1,501,667,958,000 | Lean | UTF-8 | Lean | false | false | 5,694 | lean | /- Copyright (c) 2019 Seul Baek. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Seul Baek
A tactic for discharging linear integer & natural
number arithmetic goals using the Omega test. -/
import tactic.omega.int.main
import tactic.omega.nat.main
import tactic.doc_commands
namespace omega
open tactic
meta def select_domain (t s : tactic (option bool)) : tactic (option bool) :=
do a ← t, b ← s,
match a, b with
| a, none := return a
| none, b := return b
| (some tt), (some tt) := return (some tt)
| (some ff), (some ff) := return (some ff)
| _, _ := failed
end
meta def type_domain (x : expr) : tactic (option bool) :=
if x = `(int)
then return (some tt)
else if x = `(nat)
then return (some ff)
else failed
/-- Detects domain of a formula from its expr.
* Returns none, if domain can be either ℤ or ℕ
* Returns some tt, if domain is exclusively ℤ
* Returns some ff, if domain is exclusively ℕ
* Fails, if domain is neither ℤ nor ℕ -/
meta def form_domain : expr → tactic (option bool)
| `(¬ %%px) := form_domain px
| `(%%px ∨ %%qx) := select_domain (form_domain px) (form_domain qx)
| `(%%px ∧ %%qx) := select_domain (form_domain px) (form_domain qx)
| `(%%px ↔ %%qx) := select_domain (form_domain px) (form_domain qx)
| `(%%(expr.pi _ _ px qx)) :=
monad.cond
(if expr.has_var px then return tt else is_prop px)
(select_domain (form_domain px) (form_domain qx))
(select_domain (type_domain px) (form_domain qx))
| `(@has_lt.lt %%dx %%h _ _) := type_domain dx
| `(@has_le.le %%dx %%h _ _) := type_domain dx
| `(@eq %%dx _ _) := type_domain dx
| `(@ge %%dx %%h _ _) := type_domain dx
| `(@gt %%dx %%h _ _) := type_domain dx
| `(@ne %%dx _ _) := type_domain dx
| `(true) := return none
| `(false) := return none
| x := failed
meta def goal_domain_aux (x : expr) : tactic bool :=
(omega.int.wff x >> return tt) <|> (omega.nat.wff x >> return ff)
/-- Use the current goal to determine.
Return tt if the domain is ℤ, and return ff if it is ℕ -/
meta def goal_domain : tactic bool :=
do gx ← target,
hxs ← local_context >>= monad.mapm infer_type,
app_first goal_domain_aux (gx::hxs)
/-- Return tt if the domain is ℤ, and return ff if it is ℕ -/
meta def determine_domain (opt : list name) : tactic bool :=
if `int ∈ opt
then return tt
else if `nat ∈ opt
then return ff
else goal_domain
end omega
open lean.parser interactive omega
/-- Attempts to discharge goals in the quantifier-free fragment of
linear integer and natural number arithmetic using the Omega test.
Guesses the correct domain by looking at the goal and hypotheses,
and then reverts all relevant hypotheses and variables.
Use `omega manual` to disable automatic reverts, and `omega int` or
`omega nat` to specify the domain.
-/
meta def tactic.interactive.omega (opt : parse (many ident)) : tactic unit :=
do is_int ← determine_domain opt,
let is_manual : bool := if `manual ∈ opt then tt else ff,
if is_int
then omega_int is_manual
else omega_nat is_manual
add_hint_tactic "omega"
declare_trace omega
/--
`omega` attempts to discharge goals in the quantifier-free fragment of linear integer and natural number arithmetic using the Omega test. In other words, the core procedure of `omega` works with goals of the form
```lean
∀ x₁, ... ∀ xₖ, P
```
where `x₁, ... xₖ` are integer (resp. natural number) variables, and `P` is a quantifier-free formula of linear integer (resp. natural number) arithmetic. For instance:
```lean
example : ∀ (x y : int), (x ≤ 5 ∧ y ≤ 3) → x + y ≤ 8 := by omega
```
By default, `omega` tries to guess the correct domain by looking at the goal and hypotheses, and then reverts all relevant hypotheses and variables (e.g., all variables of type `nat` and `Prop`s in linear natural number arithmetic, if the domain was determined to be `nat`) to universally close the goal before calling the main procedure. Therefore, `omega` will often work even if the goal is not in the above form:
```lean
example (x y : nat) (h : 2 * x + 1 = 2 * y) : false := by omega
```
But this behaviour is not always optimal, since it may revert irrelevant hypotheses or incorrectly guess the domain. Use `omega manual` to disable automatic reverts, and `omega int` or `omega nat` to specify the domain.
```lean
example (x y z w : int) (h1 : 3 * y ≥ x) (h2 : z > 19 * w) : 3 * x ≤ 9 * y :=
by {revert h1 x y, omega manual}
example (i : int) (n : nat) (h1 : i = 0) (h2 : n < n) : false := by omega nat
example (n : nat) (h1 : n < 34) (i : int) (h2 : i * 9 = -72) : i = -8 :=
by {revert h2 i, omega manual int}
```
`omega` handles `nat` subtraction by repeatedly rewriting goals of the form `P[t-s]` into `P[x] ∧ (t = s + x ∨ (t ≤ s ∧ x = 0))`, where `x` is fresh. This means that each (distinct) occurrence of subtraction will cause the goal size to double during DNF transformation.
`omega` implements the real shadow step of the Omega test, but not the dark and gray shadows. Therefore, it should (in principle) succeed whenever the negation of the goal has no real solution, but it may fail if a real solution exists, even if there is no integer/natural number solution.
You can enable `set_option trace.omega true` to see how `omega` interprets your goal.
-/
add_tactic_doc
{ name := "omega",
category := doc_category.tactic,
decl_names := [`tactic.interactive.omega],
tags := ["finishing", "arithmetic", "decision procedure"] }
|
30b6330857cc1f9e228c7cbbcc1d84cfccf02305 | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /src/lake/Lake/Build/Key.lean | 6b1ebd9377ef43173297e30fbde322f5210e317d | [
"Apache-2.0",
"LLVM-exception",
"NCSA",
"LGPL-3.0-only",
"LicenseRef-scancode-inner-net-2.0",
"BSD-3-Clause",
"LGPL-2.0-or-later",
"Spencer-94",
"LGPL-2.1-or-later",
"HPND",
"LicenseRef-scancode-pcre",
"ISC",
"LGPL-2.1-only",
"LicenseRef-scancode-other-permissive",
"SunPro",
"CMU-Mach"... | permissive | leanprover/lean4 | 4bdf9790294964627eb9be79f5e8f6157780b4cc | f1f9dc0f2f531af3312398999d8b8303fa5f096b | refs/heads/master | 1,693,360,665,786 | 1,693,350,868,000 | 1,693,350,868,000 | 129,571,436 | 2,827 | 311 | Apache-2.0 | 1,694,716,156,000 | 1,523,760,560,000 | Lean | UTF-8 | Lean | false | false | 2,889 | lean | /-
Copyright (c) 2022 Mac Malone. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mac Malone
-/
import Lake.Util.Name
namespace Lake
/-- The type of keys in the Lake build store. -/
inductive BuildKey
| moduleFacet (module : Name) (facet : Name)
| packageFacet (package : Name) (facet : Name)
| targetFacet (package : Name) (target : Name) (facet : Name)
| customTarget (package : Name) (target : Name)
deriving Inhabited, Repr, DecidableEq, Hashable
namespace BuildKey
def toString : (self : BuildKey) → String
| moduleFacet m f => s!"+{m}:{f}"
| packageFacet p f => s!"@{p}:{f}"
| targetFacet p t f => s!"{p}/{t}:{f}"
| customTarget p t => s!"{p}/{t}"
instance : ToString BuildKey := ⟨(·.toString)⟩
def quickCmp (k k' : BuildKey) : Ordering :=
match k with
| moduleFacet m f =>
match k' with
| moduleFacet m' f' =>
match m.quickCmp m' with
| .eq => f.quickCmp f'
| ord => ord
| _ => .lt
| packageFacet p f =>
match k' with
| moduleFacet .. => .gt
| packageFacet p' f' =>
match p.quickCmp p' with
| .eq => f.quickCmp f'
| ord => ord
| _ => .lt
| targetFacet p t f =>
match k' with
| customTarget .. => .lt
| targetFacet p' t' f' =>
match p.quickCmp p' with
| .eq =>
match t.quickCmp t' with
| .eq => f.quickCmp f'
| ord => ord
| ord => ord
| _=> .gt
| customTarget p t =>
match k' with
| customTarget p' t' =>
match p.quickCmp p' with
| .eq => t.quickCmp t'
| ord => ord
| _ => .gt
theorem eq_of_quickCmp {k k' : BuildKey} :
quickCmp k k' = Ordering.eq → k = k' := by
unfold quickCmp
cases k with
| moduleFacet m f =>
cases k'
case moduleFacet m' f' =>
dsimp only; split
next m_eq => intro f_eq; rw [eq_of_cmp m_eq, eq_of_cmp f_eq]
next => intro; contradiction
all_goals (intro; contradiction)
| packageFacet p f =>
cases k'
case packageFacet p' f' =>
dsimp only; split
next p_eq => intro f_eq; rw [eq_of_cmp p_eq, eq_of_cmp f_eq]
next => intro; contradiction
all_goals (intro; contradiction)
| targetFacet p t f =>
cases k'
case targetFacet p' t' f' =>
dsimp only; split
next p_eq =>
split
next t_eq =>
intro f_eq
rw [eq_of_cmp p_eq, eq_of_cmp t_eq, eq_of_cmp f_eq]
next => intro; contradiction
next => intro; contradiction
all_goals (intro; contradiction)
| customTarget p t =>
cases k'
case customTarget p' t' =>
dsimp only; split
next p_eq => intro t_eq; rw [eq_of_cmp p_eq, eq_of_cmp t_eq]
next => intro; contradiction
all_goals (intro; contradiction)
instance : LawfulCmpEq BuildKey quickCmp where
eq_of_cmp := eq_of_quickCmp
cmp_rfl {k} := by cases k <;> simp [quickCmp]
|
e8fc22497c09ffe8624a396bb24064c533449075 | 947fa6c38e48771ae886239b4edce6db6e18d0fb | /src/field_theory/primitive_element.lean | 83c0feb67ce2690970d3d04a2d0ed805e245a6ff | [
"Apache-2.0"
] | permissive | ramonfmir/mathlib | c5dc8b33155473fab97c38bd3aa6723dc289beaa | 14c52e990c17f5a00c0cc9e09847af16fabbed25 | refs/heads/master | 1,661,979,343,526 | 1,660,830,384,000 | 1,660,830,384,000 | 182,072,989 | 0 | 0 | null | 1,555,585,876,000 | 1,555,585,876,000 | null | UTF-8 | Lean | false | false | 8,812 | lean | /-
Copyright (c) 2020 Thomas Browning, Patrick Lutz. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Thomas Browning, Patrick Lutz
-/
import field_theory.adjoin
import field_theory.fixed
import field_theory.is_alg_closed.basic
import field_theory.separable
import ring_theory.integral_domain
/-!
# 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
-/
noncomputable theory
open_locale classical polynomial
open finite_dimensional polynomial intermediate_field
namespace field
section primitive_element_finite
variables (F : Type*) [field F] (E : Type*) [field E] [algebra F E]
/-! ### Primitive element theorem for finite fields -/
/-- **Primitive element theorem** assuming E is finite. -/
lemma exists_primitive_element_of_fintype_top [fintype E] : ∃ α : E, F⟮α⟯ = ⊤ :=
begin
obtain ⟨α, hα⟩ := is_cyclic.exists_generator (units E),
use α,
apply eq_top_iff.mpr,
rintros x -,
by_cases hx : x = 0,
{ rw hx,
exact F⟮α.val⟯.zero_mem },
{ obtain ⟨n, hn⟩ := set.mem_range.mp (hα (units.mk0 x hx)),
rw (show x = α^n, by { norm_cast, rw [hn, units.coe_mk0] }),
exact zpow_mem (mem_adjoin_simple_self F ↑α) n, },
end
/-- Primitive element theorem for finite dimensional extension of a finite field. -/
theorem exists_primitive_element_of_fintype_bot [fintype F] [finite_dimensional F E] :
∃ α : E, F⟮α⟯ = ⊤ :=
begin
haveI : fintype E := fintype_of_fintype F E,
exact exists_primitive_element_of_fintype_top F E,
end
end primitive_element_finite
/-! ### Primitive element theorem for infinite fields -/
section primitive_element_inf
variables {F : Type*} [field F] [infinite F] {E : Type*} [field E] (ϕ : F →+* E) (α β : E)
lemma primitive_element_inf_aux_exists_c (f g : F[X]) :
∃ c : F, ∀ (α' ∈ (f.map ϕ).roots) (β' ∈ (g.map ϕ).roots), -(α' - α)/(β' - β) ≠ ϕ c :=
begin
let sf := (f.map ϕ).roots,
let sg := (g.map ϕ).roots,
let s := (sf.bind (λ α', sg.map (λ β', -(α' - α) / (β' - β)))).to_finset,
let s' := s.preimage ϕ (λ x hx y hy h, ϕ.injective h),
obtain ⟨c, hc⟩ := infinite.exists_not_mem_finset s',
simp_rw [finset.mem_preimage, multiset.mem_to_finset, multiset.mem_bind, multiset.mem_map] at hc,
push_neg at hc,
exact ⟨c, hc⟩,
end
variables (F) [algebra F E]
-- 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.
lemma primitive_element_inf_aux [is_separable F E] :
∃ γ : E, F⟮α, β⟯ = F⟮γ⟯ :=
begin
have hα := is_separable.is_integral F α,
have hβ := is_separable.is_integral F β,
let f := minpoly F α,
let g := minpoly F β,
let ιFE := algebra_map F E,
let ιEE' := algebra_map E (splitting_field (g.map ιFE)),
obtain ⟨c, hc⟩ := primitive_element_inf_aux_exists_c (ιEE'.comp ιFE) (ιEE' α) (ιEE' β) f g,
let γ := α + c • β,
suffices β_in_Fγ : β ∈ F⟮γ⟯,
{ use γ,
apply le_antisymm,
{ rw adjoin_le_iff,
have α_in_Fγ : α ∈ F⟮γ⟯,
{ rw ← add_sub_cancel α (c • β),
exact F⟮γ⟯.sub_mem (mem_adjoin_simple_self F γ) (F⟮γ⟯.to_subalgebra.smul_mem β_in_Fγ c) },
exact λ x hx, by cases hx; cases hx; cases hx; assumption },
{ rw [adjoin_simple_le_iff],
have α_in_Fαβ : α ∈ F⟮α, β⟯ := subset_adjoin F {α, β} (set.mem_insert α {β}),
have β_in_Fαβ : β ∈ F⟮α, β⟯ := subset_adjoin F {α, β} (set.mem_insert_of_mem α rfl),
exact F⟮α,β⟯.add_mem α_in_Fαβ (F⟮α, β⟯.smul_mem β_in_Fαβ) } },
let p := euclidean_domain.gcd ((f.map (algebra_map F F⟮γ⟯)).comp
(C (adjoin_simple.gen F γ) - (C ↑c * X))) (g.map (algebra_map F F⟮γ⟯)),
let h := euclidean_domain.gcd ((f.map ιFE).comp (C γ - (C (ιFE c) * X))) (g.map ιFE),
have map_g_ne_zero : g.map ιFE ≠ 0 := map_ne_zero (minpoly.ne_zero hβ),
have h_ne_zero : h ≠ 0 := mt euclidean_domain.gcd_eq_zero_iff.mp
(not_and.mpr (λ _, map_g_ne_zero)),
suffices p_linear : p.map (algebra_map F⟮γ⟯ E) = (C h.leading_coeff) * (X - C β),
{ have finale : β = algebra_map F⟮γ⟯ E (-p.coeff 0 / p.coeff 1),
{ rw [map_div₀, ring_hom.map_neg, ←coeff_map, ←coeff_map, p_linear],
simp [mul_sub, coeff_C, mul_div_cancel_left β (mt leading_coeff_eq_zero.mp h_ne_zero)] },
rw finale,
exact subtype.mem (-p.coeff 0 / p.coeff 1) },
have h_sep : h.separable := separable_gcd_right _ (is_separable.separable F β).map,
have h_root : h.eval β = 0,
{ apply eval_gcd_eq_zero,
{ rw [eval_comp, eval_sub, eval_mul, eval_C, eval_C, eval_X, eval_map, ←aeval_def,
←algebra.smul_def, add_sub_cancel, minpoly.aeval] },
{ rw [eval_map, ←aeval_def, minpoly.aeval] } },
have h_splits : splits ιEE' h := splits_of_splits_gcd_right ιEE' map_g_ne_zero
(splitting_field.splits _),
have h_roots : ∀ x ∈ (h.map ιEE').roots, x = ιEE' β,
{ intros x hx,
rw mem_roots_map h_ne_zero at hx,
specialize hc ((ιEE' γ) - (ιEE' (ιFE c)) * x) (begin
have f_root := root_left_of_root_gcd hx,
rw [eval₂_comp, eval₂_sub, eval₂_mul,eval₂_C, eval₂_C, eval₂_X, eval₂_map] at f_root,
exact (mem_roots_map (minpoly.ne_zero hα)).mpr f_root,
end),
specialize hc x (begin
rw [mem_roots_map (minpoly.ne_zero hβ), ←eval₂_map],
exact root_right_of_root_gcd hx,
end),
by_contradiction a,
apply hc,
apply (div_eq_iff (sub_ne_zero.mpr a)).mpr,
simp only [algebra.smul_def, ring_hom.map_add, ring_hom.map_mul, ring_hom.comp_apply],
ring },
rw ← eq_X_sub_C_of_separable_of_root_eq h_sep h_root h_splits h_roots,
transitivity euclidean_domain.gcd (_ : E[X]) (_ : E[X]),
{ dsimp only [p],
convert (gcd_map (algebra_map F⟮γ⟯ E)).symm },
{ simpa [map_comp, polynomial.map_map, ←is_scalar_tower.algebra_map_eq, h] },
end
end primitive_element_inf
variables (F E : Type*) [field F] [field E]
variables [algebra F E] [finite_dimensional F E]
section separable_assumption
variable [is_separable F E]
/-- 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 : ∃ α : E, F⟮α⟯ = ⊤ :=
begin
rcases is_empty_or_nonempty (fintype F) with F_inf|⟨⟨F_finite⟩⟩,
{ let P : intermediate_field F E → Prop := λ K, ∃ α : E, F⟮α⟯ = K,
have base : P ⊥ := ⟨0, adjoin_zero⟩,
have ih : ∀ (K : intermediate_field F E) (x : E), P K → P (K⟮x⟯.restrict_scalars F),
{ intros K β hK,
cases hK with α hK,
rw [←hK, adjoin_simple_adjoin_simple],
haveI : infinite F := is_empty_fintype.mp F_inf,
cases primitive_element_inf_aux F α β with γ hγ,
exact ⟨γ, hγ.symm⟩ },
exact induction_on_adjoin P base ih ⊤ },
{ exactI exists_primitive_element_of_fintype_bot F E }
end
/-- Alternative phrasing of primitive element theorem:
a finite separable field extension has a basis `1, α, α^2, ..., α^n`.
See also `exists_primitive_element`. -/
noncomputable def power_basis_of_finite_of_separable : power_basis F E :=
let α := (exists_primitive_element F E).some,
pb := (adjoin.power_basis (is_separable.is_integral F α)) in
have e : F⟮α⟯ = ⊤ := (exists_primitive_element F E).some_spec,
pb.map ((intermediate_field.equiv_of_eq e).trans intermediate_field.top_equiv)
end separable_assumption
end field
@[simp] lemma alg_hom.card (F E K : Type*) [field F] [field E] [field K] [is_alg_closed K]
[algebra F E] [finite_dimensional F E] [is_separable F E] [algebra F K] :
fintype.card (E →ₐ[F] K) = finrank F E :=
begin
convert (alg_hom.card_of_power_basis (field.power_basis_of_finite_of_separable F E)
(is_separable.separable _ _) (is_alg_closed.splits_codomain _)).trans
(power_basis.finrank _).symm,
apply_instance,
end
|
29c251a94346c95edc2c02451860c38809c54a52 | dd0f5513e11c52db157d2fcc8456d9401a6cd9da | /08_Building_Theories_and_Proofs.org.3.lean | a6a162e8f7ba469fd03f1dfb3cb3a7b92e6b7593 | [] | no_license | cjmazey/lean-tutorial | ba559a49f82aa6c5848b9bf17b7389bf7f4ba645 | 381f61c9fcac56d01d959ae0fa6e376f2c4e3b34 | refs/heads/master | 1,610,286,098,832 | 1,447,124,923,000 | 1,447,124,923,000 | 43,082,433 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 354 | lean | import standard
structure Semigroup : Type :=
(carrier : Type)
(mul : carrier → carrier → carrier)
(mul_assoc : ∀ a b c : carrier, mul (mul a b) c = mul a (mul b c))
notation a `*` b := Semigroup.mul _ a b
-- BEGIN
attribute Semigroup.carrier [coercion]
example (S : Semigroup) (a b : S) : a * b * a = a * (b * a) :=
!Semigroup.mul_assoc
-- END
|
2f76d8d66be1067f32178843889e5e8020f0f295 | 367134ba5a65885e863bdc4507601606690974c1 | /src/topology/basic.lean | 50485c7c6c6f995594e0fed701387b78fd37a2ba | [
"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 | 54,021 | lean | /-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Mario Carneiro, Jeremy Avigad
-/
import order.filter.ultrafilter
import order.filter.partial
noncomputable theory
/-!
# Basic theory of topological spaces.
The main definition is the type class `topological space α` which endows a type `α` with a topology.
Then `set α` gets predicates `is_open`, `is_closed` and functions `interior`, `closure` and
`frontier`. Each point `x` of `α` gets a neighborhood filter `𝓝 x`. A filter `F` on `α` has
`x` as a cluster point if `cluster_pt x F : 𝓝 x ⊓ F ≠ ⊥`. A map `f : ι → α` clusters at `x`
along `F : filter ι` if `map_cluster_pt x F f : cluster_pt x (map f F)`. In particular
the notion of cluster point of a sequence `u` is `map_cluster_pt x at_top u`.
This file also defines locally finite families of subsets of `α`.
For topological spaces `α` and `β`, a function `f : α → β` and a point `a : α`,
`continuous_at f a` means `f` is continuous at `a`, and global continuity is
`continuous f`. There is also a version of continuity `pcontinuous` for
partially defined functions.
## Notation
* `𝓝 x`: the filter of neighborhoods of a point `x`;
* `𝓟 s`: the principal filter of a set `s`;
* `𝓝[s] x`: the filter `nhds_within x s` of neighborhoods of a point `x` within a set `s`.
## Implementation notes
Topology in mathlib heavily uses filters (even more than in Bourbaki). See explanations in
<https://leanprover-community.github.io/theories/topology.html>.
## References
* [N. Bourbaki, *General Topology*][bourbaki1966]
* [I. M. James, *Topologies and Uniformities*][james1999]
## Tags
topological space, interior, closure, frontier, neighborhood, continuity, continuous function
-/
open set filter classical
open_locale classical filter
universes u v w
/-!
### Topological spaces
-/
/-- A topology on `α`. -/
@[protect_proj] structure topological_space (α : Type u) :=
(is_open : set α → Prop)
(is_open_univ : is_open univ)
(is_open_inter : ∀s t, is_open s → is_open t → is_open (s ∩ t))
(is_open_sUnion : ∀s, (∀t∈s, is_open t) → is_open (⋃₀ s))
attribute [class] topological_space
/-- A constructor for topologies by specifying the closed sets,
and showing that they satisfy the appropriate conditions. -/
def topological_space.of_closed {α : Type u} (T : set (set α))
(empty_mem : ∅ ∈ T) (sInter_mem : ∀ A ⊆ T, ⋂₀ A ∈ T) (union_mem : ∀ A B ∈ T, A ∪ B ∈ T) :
topological_space α :=
{ is_open := λ X, Xᶜ ∈ T,
is_open_univ := by simp [empty_mem],
is_open_inter := λ s t hs ht, by simpa [set.compl_inter] using union_mem sᶜ tᶜ hs ht,
is_open_sUnion := λ s hs,
by rw set.compl_sUnion; exact sInter_mem (set.compl '' s)
(λ z ⟨y, hy, hz⟩, by simpa [hz.symm] using hs y hy) }
section topological_space
variables {α : Type u} {β : Type v} {ι : Sort w} {a : α} {s s₁ s₂ : set α} {p p₁ p₂ : α → Prop}
@[ext]
lemma topological_space_eq : ∀ {f g : topological_space α}, f.is_open = g.is_open → f = g
| ⟨a, _, _, _⟩ ⟨b, _, _, _⟩ rfl := rfl
section
variables [t : topological_space α]
include t
/-- `is_open s` means that `s` is open in the ambient topological space on `α` -/
def is_open (s : set α) : Prop := topological_space.is_open t s
@[simp]
lemma is_open_univ : is_open (univ : set α) := topological_space.is_open_univ t
lemma is_open_inter (h₁ : is_open s₁) (h₂ : is_open s₂) : is_open (s₁ ∩ s₂) :=
topological_space.is_open_inter t s₁ s₂ h₁ h₂
lemma is_open_sUnion {s : set (set α)} (h : ∀t ∈ s, is_open t) : is_open (⋃₀ s) :=
topological_space.is_open_sUnion t s h
end
lemma topological_space_eq_iff {t t' : topological_space α} :
t = t' ↔ ∀ s, @is_open α t s ↔ @is_open α t' s :=
⟨λ h s, h ▸ iff.rfl, λ h, by { ext, exact h _ }⟩
lemma is_open_fold {s : set α} {t : topological_space α} : t.is_open s = @is_open α t s :=
rfl
variables [topological_space α]
lemma is_open_Union {f : ι → set α} (h : ∀i, is_open (f i)) : is_open (⋃i, f i) :=
is_open_sUnion $ by rintro _ ⟨i, rfl⟩; exact h i
lemma is_open_bUnion {s : set β} {f : β → set α} (h : ∀i∈s, is_open (f i)) :
is_open (⋃i∈s, f i) :=
is_open_Union $ assume i, is_open_Union $ assume hi, h i hi
lemma is_open_union (h₁ : is_open s₁) (h₂ : is_open s₂) : is_open (s₁ ∪ s₂) :=
by rw union_eq_Union; exact is_open_Union (bool.forall_bool.2 ⟨h₂, h₁⟩)
@[simp] lemma is_open_empty : is_open (∅ : set α) :=
by rw ← sUnion_empty; exact is_open_sUnion (assume a, false.elim)
lemma is_open_sInter {s : set (set α)} (hs : finite s) : (∀t ∈ s, is_open t) → is_open (⋂₀ s) :=
finite.induction_on hs (λ _, by rw sInter_empty; exact is_open_univ) $
λ a s has hs ih h, by rw sInter_insert; exact
is_open_inter (h _ $ mem_insert _ _) (ih $ λ t, h t ∘ mem_insert_of_mem _)
lemma is_open_bInter {s : set β} {f : β → set α} (hs : finite s) :
(∀i∈s, is_open (f i)) → is_open (⋂i∈s, f i) :=
finite.induction_on hs
(λ _, by rw bInter_empty; exact is_open_univ)
(λ a s has hs ih h, by rw bInter_insert; exact
is_open_inter (h a (mem_insert _ _)) (ih (λ i hi, h i (mem_insert_of_mem _ hi))))
lemma is_open_Inter [fintype β] {s : β → set α}
(h : ∀ i, is_open (s i)) : is_open (⋂ i, s i) :=
suffices is_open (⋂ (i : β) (hi : i ∈ @univ β), s i), by simpa,
is_open_bInter finite_univ (λ i _, h i)
lemma is_open_Inter_prop {p : Prop} {s : p → set α}
(h : ∀ h : p, is_open (s h)) : is_open (Inter s) :=
by by_cases p; simp *
lemma is_open_const {p : Prop} : is_open {a : α | p} :=
by_cases
(assume : p, begin simp only [this]; exact is_open_univ end)
(assume : ¬ p, begin simp only [this]; exact is_open_empty end)
lemma is_open_and : is_open {a | p₁ a} → is_open {a | p₂ a} → is_open {a | p₁ a ∧ p₂ a} :=
is_open_inter
/-- A set is closed if its complement is open -/
class is_closed (s : set α) : Prop :=
(is_open_compl : is_open sᶜ)
@[simp] lemma is_open_compl_iff {s : set α} : is_open sᶜ ↔ is_closed s :=
⟨λ h, ⟨h⟩, λ h, h.is_open_compl⟩
@[simp] lemma is_closed_empty : is_closed (∅ : set α) :=
by { rw [← is_open_compl_iff, compl_empty], exact is_open_univ }
@[simp] lemma is_closed_univ : is_closed (univ : set α) :=
by { rw [← is_open_compl_iff, compl_univ], exact is_open_empty }
lemma is_closed_union : is_closed s₁ → is_closed s₂ → is_closed (s₁ ∪ s₂) :=
λ h₁ h₂, by { rw [← is_open_compl_iff] at *, rw compl_union, exact is_open_inter h₁ h₂ }
lemma is_closed_sInter {s : set (set α)} : (∀t ∈ s, is_closed t) → is_closed (⋂₀ s) :=
by simpa only [← is_open_compl_iff, compl_sInter, sUnion_image] using is_open_bUnion
lemma is_closed_Inter {f : ι → set α} (h : ∀i, is_closed (f i)) : is_closed (⋂i, f i ) :=
is_closed_sInter $ assume t ⟨i, (heq : f i = t)⟩, heq ▸ h i
lemma is_closed_bInter {s : set β} {f : β → set α} (h : ∀ i ∈ s, is_closed (f i)) :
is_closed (⋂ i ∈ s, f i) :=
is_closed_Inter $ λ i, is_closed_Inter $ h i
@[simp] lemma is_closed_compl_iff {s : set α} : is_closed sᶜ ↔ is_open s :=
by rw [←is_open_compl_iff, compl_compl]
lemma is_open.is_closed_compl {s : set α} (hs : is_open s) : is_closed sᶜ :=
is_closed_compl_iff.2 hs
lemma is_open_diff {s t : set α} (h₁ : is_open s) (h₂ : is_closed t) : is_open (s \ t) :=
is_open_inter h₁ $ is_open_compl_iff.mpr h₂
lemma is_closed_inter (h₁ : is_closed s₁) (h₂ : is_closed s₂) : is_closed (s₁ ∩ s₂) :=
by { rw [← is_open_compl_iff] at *, rw compl_inter, exact is_open_union h₁ h₂ }
lemma is_closed_bUnion {s : set β} {f : β → set α} (hs : finite s) :
(∀i∈s, is_closed (f i)) → is_closed (⋃i∈s, f i) :=
finite.induction_on hs
(λ _, by rw bUnion_empty; exact is_closed_empty)
(λ a s has hs ih h, by rw bUnion_insert; exact
is_closed_union (h a (mem_insert _ _)) (ih (λ i hi, h i (mem_insert_of_mem _ hi))))
lemma is_closed_Union [fintype β] {s : β → set α}
(h : ∀ i, is_closed (s i)) : is_closed (Union s) :=
suffices is_closed (⋃ (i : β) (hi : i ∈ @univ β), s i),
by convert this; simp [set.ext_iff],
is_closed_bUnion finite_univ (λ i _, h i)
lemma is_closed_Union_prop {p : Prop} {s : p → set α}
(h : ∀ h : p, is_closed (s h)) : is_closed (Union s) :=
by by_cases p; simp *
lemma is_closed_imp {p q : α → Prop} (hp : is_open {x | p x})
(hq : is_closed {x | q x}) : is_closed {x | p x → q x} :=
have {x | p x → q x} = {x | p x}ᶜ ∪ {x | q x}, from set.ext $ λ x, imp_iff_not_or,
by rw [this]; exact is_closed_union (is_closed_compl_iff.mpr hp) hq
lemma is_open_neg : is_closed {a | p a} → is_open {a | ¬ p a} :=
is_open_compl_iff.mpr
/-!
### Interior of a set
-/
/-- The interior of a set `s` is the largest open subset of `s`. -/
def interior (s : set α) : set α := ⋃₀ {t | is_open t ∧ t ⊆ s}
lemma mem_interior {s : set α} {x : α} :
x ∈ interior s ↔ ∃ t ⊆ s, is_open t ∧ x ∈ t :=
by simp only [interior, mem_set_of_eq, exists_prop, and_assoc, and.left_comm]
@[simp] lemma is_open_interior {s : set α} : is_open (interior s) :=
is_open_sUnion $ assume t ⟨h₁, h₂⟩, h₁
lemma interior_subset {s : set α} : interior s ⊆ s :=
sUnion_subset $ assume t ⟨h₁, h₂⟩, h₂
lemma interior_maximal {s t : set α} (h₁ : t ⊆ s) (h₂ : is_open t) : t ⊆ interior s :=
subset_sUnion_of_mem ⟨h₂, h₁⟩
lemma is_open.interior_eq {s : set α} (h : is_open s) : interior s = s :=
subset.antisymm interior_subset (interior_maximal (subset.refl s) h)
lemma interior_eq_iff_open {s : set α} : interior s = s ↔ is_open s :=
⟨assume h, h ▸ is_open_interior, is_open.interior_eq⟩
lemma subset_interior_iff_open {s : set α} : s ⊆ interior s ↔ is_open s :=
by simp only [interior_eq_iff_open.symm, subset.antisymm_iff, interior_subset, true_and]
lemma subset_interior_iff_subset_of_open {s t : set α} (h₁ : is_open s) :
s ⊆ interior t ↔ s ⊆ t :=
⟨assume h, subset.trans h interior_subset, assume h₂, interior_maximal h₂ h₁⟩
lemma interior_mono {s t : set α} (h : s ⊆ t) : interior s ⊆ interior t :=
interior_maximal (subset.trans interior_subset h) is_open_interior
@[simp] lemma interior_empty : interior (∅ : set α) = ∅ :=
is_open_empty.interior_eq
@[simp] lemma interior_univ : interior (univ : set α) = univ :=
is_open_univ.interior_eq
@[simp] lemma interior_interior {s : set α} : interior (interior s) = interior s :=
is_open_interior.interior_eq
@[simp] lemma interior_inter {s t : set α} : interior (s ∩ t) = interior s ∩ interior t :=
subset.antisymm
(subset_inter (interior_mono $ inter_subset_left s t) (interior_mono $ inter_subset_right s t))
(interior_maximal (inter_subset_inter interior_subset interior_subset) $
is_open_inter is_open_interior is_open_interior)
lemma interior_union_is_closed_of_interior_empty {s t : set α} (h₁ : is_closed s)
(h₂ : interior t = ∅) :
interior (s ∪ t) = interior s :=
have interior (s ∪ t) ⊆ s, from
assume x ⟨u, ⟨(hu₁ : is_open u), (hu₂ : u ⊆ s ∪ t)⟩, (hx₁ : x ∈ u)⟩,
classical.by_contradiction $ assume hx₂ : x ∉ s,
have u \ s ⊆ t,
from assume x ⟨h₁, h₂⟩, or.resolve_left (hu₂ h₁) h₂,
have u \ s ⊆ interior t,
by rwa subset_interior_iff_subset_of_open (is_open_diff hu₁ h₁),
have u \ s ⊆ ∅,
by rwa h₂ at this,
this ⟨hx₁, hx₂⟩,
subset.antisymm
(interior_maximal this is_open_interior)
(interior_mono $ subset_union_left _ _)
lemma is_open_iff_forall_mem_open : is_open s ↔ ∀ x ∈ s, ∃ t ⊆ s, is_open t ∧ x ∈ t :=
by rw ← subset_interior_iff_open; simp only [subset_def, mem_interior]
/-!
### Closure of a set
-/
/-- The closure of `s` is the smallest closed set containing `s`. -/
def closure (s : set α) : set α := ⋂₀ {t | is_closed t ∧ s ⊆ t}
@[simp] lemma is_closed_closure {s : set α} : is_closed (closure s) :=
is_closed_sInter $ assume t ⟨h₁, h₂⟩, h₁
lemma subset_closure {s : set α} : s ⊆ closure s :=
subset_sInter $ assume t ⟨h₁, h₂⟩, h₂
lemma closure_minimal {s t : set α} (h₁ : s ⊆ t) (h₂ : is_closed t) : closure s ⊆ t :=
sInter_subset_of_mem ⟨h₂, h₁⟩
lemma is_closed.closure_eq {s : set α} (h : is_closed s) : closure s = s :=
subset.antisymm (closure_minimal (subset.refl s) h) subset_closure
lemma is_closed.closure_subset {s : set α} (hs : is_closed s) : closure s ⊆ s :=
closure_minimal (subset.refl _) hs
lemma is_closed.closure_subset_iff {s t : set α} (h₁ : is_closed t) :
closure s ⊆ t ↔ s ⊆ t :=
⟨subset.trans subset_closure, assume h, closure_minimal h h₁⟩
@[mono] lemma closure_mono {s t : set α} (h : s ⊆ t) : closure s ⊆ closure t :=
closure_minimal (subset.trans h subset_closure) is_closed_closure
lemma monotone_closure (α : Type*) [topological_space α] : monotone (@closure α _) :=
λ _ _, closure_mono
lemma diff_subset_closure_iff {s t : set α} :
s \ t ⊆ closure t ↔ s ⊆ closure t :=
by rw [diff_subset_iff, union_eq_self_of_subset_left subset_closure]
lemma closure_inter_subset_inter_closure (s t : set α) :
closure (s ∩ t) ⊆ closure s ∩ closure t :=
(monotone_closure α).map_inf_le s t
lemma is_closed_of_closure_subset {s : set α} (h : closure s ⊆ s) : is_closed s :=
by rw subset.antisymm subset_closure h; exact is_closed_closure
lemma closure_eq_iff_is_closed {s : set α} : closure s = s ↔ is_closed s :=
⟨assume h, h ▸ is_closed_closure, is_closed.closure_eq⟩
lemma closure_subset_iff_is_closed {s : set α} : closure s ⊆ s ↔ is_closed s :=
⟨is_closed_of_closure_subset, is_closed.closure_subset⟩
@[simp] lemma closure_empty : closure (∅ : set α) = ∅ :=
is_closed_empty.closure_eq
@[simp] lemma closure_empty_iff (s : set α) : closure s = ∅ ↔ s = ∅ :=
⟨subset_eq_empty subset_closure, λ h, h.symm ▸ closure_empty⟩
@[simp] lemma closure_nonempty_iff {s : set α} : (closure s).nonempty ↔ s.nonempty :=
by simp only [← ne_empty_iff_nonempty, ne.def, closure_empty_iff]
alias closure_nonempty_iff ↔ set.nonempty.of_closure set.nonempty.closure
@[simp] lemma closure_univ : closure (univ : set α) = univ :=
is_closed_univ.closure_eq
@[simp] lemma closure_closure {s : set α} : closure (closure s) = closure s :=
is_closed_closure.closure_eq
@[simp] lemma closure_union {s t : set α} : closure (s ∪ t) = closure s ∪ closure t :=
subset.antisymm
(closure_minimal (union_subset_union subset_closure subset_closure) $
is_closed_union is_closed_closure is_closed_closure)
((monotone_closure α).le_map_sup s t)
lemma interior_subset_closure {s : set α} : interior s ⊆ closure s :=
subset.trans interior_subset subset_closure
lemma closure_eq_compl_interior_compl {s : set α} : closure s = (interior sᶜ)ᶜ :=
begin
rw [interior, closure, compl_sUnion, compl_image_set_of],
simp only [compl_subset_compl, is_open_compl_iff],
end
@[simp] lemma interior_compl {s : set α} : interior sᶜ = (closure s)ᶜ :=
by simp [closure_eq_compl_interior_compl]
@[simp] lemma closure_compl {s : set α} : closure sᶜ = (interior s)ᶜ :=
by simp [closure_eq_compl_interior_compl]
theorem mem_closure_iff {s : set α} {a : α} :
a ∈ closure s ↔ ∀ o, is_open o → a ∈ o → (o ∩ s).nonempty :=
⟨λ h o oo ao, classical.by_contradiction $ λ os,
have s ⊆ oᶜ, from λ x xs xo, os ⟨x, xo, xs⟩,
closure_minimal this (is_closed_compl_iff.2 oo) h ao,
λ H c ⟨h₁, h₂⟩, classical.by_contradiction $ λ nc,
let ⟨x, hc, hs⟩ := (H _ h₁.is_open_compl nc) in hc (h₂ hs)⟩
/-- A set is dense in a topological space if every point belongs to its closure. -/
def dense (s : set α) : Prop := ∀ x, x ∈ closure s
lemma dense_iff_closure_eq {s : set α} : dense s ↔ closure s = univ :=
eq_univ_iff_forall.symm
lemma dense.closure_eq {s : set α} (h : dense s) : closure s = univ :=
dense_iff_closure_eq.mp h
/-- The closure of a set `s` is dense if and only if `s` is dense. -/
@[simp] lemma dense_closure {s : set α} : dense (closure s) ↔ dense s :=
by rw [dense, dense, closure_closure]
alias dense_closure ↔ dense.of_closure dense.closure
@[simp] lemma dense_univ : dense (univ : set α) := λ x, subset_closure trivial
/-- A set is dense if and only if it has a nonempty intersection with each nonempty open set. -/
lemma dense_iff_inter_open {s : set α} :
dense s ↔ ∀ U, is_open U → U.nonempty → (U ∩ s).nonempty :=
begin
split ; intro h,
{ rintros U U_op ⟨x, x_in⟩,
exact mem_closure_iff.1 (by simp only [h.closure_eq]) U U_op x_in },
{ intro x,
rw mem_closure_iff,
intros U U_op x_in,
exact h U U_op ⟨_, x_in⟩ },
end
alias dense_iff_inter_open ↔ dense.inter_open_nonempty _
lemma dense.nonempty_iff {s : set α} (hs : dense s) :
s.nonempty ↔ nonempty α :=
⟨λ ⟨x, hx⟩, ⟨x⟩, λ ⟨x⟩,
let ⟨y, hy⟩ := hs.inter_open_nonempty _ is_open_univ ⟨x, trivial⟩ in ⟨y, hy.2⟩⟩
lemma dense.nonempty [h : nonempty α] {s : set α} (hs : dense s) : s.nonempty :=
hs.nonempty_iff.2 h
@[mono]
lemma dense.mono {s₁ s₂ : set α} (h : s₁ ⊆ s₂) (hd : dense s₁) : dense s₂ :=
λ x, closure_mono h (hd x)
/-!
### Frontier of a set
-/
/-- The frontier of a set is the set of points between the closure and interior. -/
def frontier (s : set α) : set α := closure s \ interior s
lemma frontier_eq_closure_inter_closure {s : set α} :
frontier s = closure s ∩ closure sᶜ :=
by rw [closure_compl, frontier, diff_eq]
/-- The complement of a set has the same frontier as the original set. -/
@[simp] lemma frontier_compl (s : set α) : frontier sᶜ = frontier s :=
by simp only [frontier_eq_closure_inter_closure, compl_compl, inter_comm]
@[simp] lemma frontier_univ : frontier (univ : set α) = ∅ := by simp [frontier]
@[simp] lemma frontier_empty : frontier (∅ : set α) = ∅ := by simp [frontier]
lemma frontier_inter_subset (s t : set α) :
frontier (s ∩ t) ⊆ (frontier s ∩ closure t) ∪ (closure s ∩ frontier t) :=
begin
simp only [frontier_eq_closure_inter_closure, compl_inter, closure_union],
convert inter_subset_inter_left _ (closure_inter_subset_inter_closure s t),
simp only [inter_distrib_left, inter_distrib_right, inter_assoc],
congr' 2,
apply inter_comm
end
lemma frontier_union_subset (s t : set α) :
frontier (s ∪ t) ⊆ (frontier s ∩ closure tᶜ) ∪ (closure sᶜ ∩ frontier t) :=
by simpa only [frontier_compl, ← compl_union]
using frontier_inter_subset sᶜ tᶜ
lemma is_closed.frontier_eq {s : set α} (hs : is_closed s) : frontier s = s \ interior s :=
by rw [frontier, hs.closure_eq]
lemma is_open.frontier_eq {s : set α} (hs : is_open s) : frontier s = closure s \ s :=
by rw [frontier, hs.interior_eq]
/-- The frontier of a set is closed. -/
lemma is_closed_frontier {s : set α} : is_closed (frontier s) :=
by rw frontier_eq_closure_inter_closure; exact is_closed_inter is_closed_closure is_closed_closure
/-- The frontier of a closed set has no interior point. -/
lemma interior_frontier {s : set α} (h : is_closed s) : interior (frontier s) = ∅ :=
begin
have A : frontier s = s \ interior s, from h.frontier_eq,
have B : interior (frontier s) ⊆ interior s, by rw A; exact interior_mono (diff_subset _ _),
have C : interior (frontier s) ⊆ frontier s := interior_subset,
have : interior (frontier s) ⊆ (interior s) ∩ (s \ interior s) :=
subset_inter B (by simpa [A] using C),
rwa [inter_diff_self, subset_empty_iff] at this,
end
lemma closure_eq_interior_union_frontier (s : set α) : closure s = interior s ∪ frontier s :=
(union_diff_cancel interior_subset_closure).symm
lemma closure_eq_self_union_frontier (s : set α) : closure s = s ∪ frontier s :=
(union_diff_cancel' interior_subset subset_closure).symm
/-!
### Neighborhoods
-/
/-- A set is called a neighborhood of `a` if it contains an open set around `a`. The set of all
neighborhoods of `a` forms a filter, the neighborhood filter at `a`, is here defined as the
infimum over the principal filters of all open sets containing `a`. -/
@[irreducible] def nhds (a : α) : filter α := (⨅ s ∈ {s : set α | a ∈ s ∧ is_open s}, 𝓟 s)
localized "notation `𝓝` := nhds" in topological_space
/-- The "neighborhood within" filter. Elements of `𝓝[s] a` are sets containing the
intersection of `s` and a neighborhood of `a`. -/
def nhds_within (a : α) (s : set α) : filter α := 𝓝 a ⊓ 𝓟 s
localized "notation `𝓝[` s `] ` x:100 := nhds_within x s" in topological_space
lemma nhds_def (a : α) : 𝓝 a = (⨅ s ∈ {s : set α | a ∈ s ∧ is_open s}, 𝓟 s) := by rw nhds
/-- The open sets containing `a` are a basis for the neighborhood filter. See `nhds_basis_opens'`
for a variant using open neighborhoods instead. -/
lemma nhds_basis_opens (a : α) : (𝓝 a).has_basis (λ s : set α, a ∈ s ∧ is_open s) (λ x, x) :=
begin
rw nhds_def,
exact has_basis_binfi_principal
(λ s ⟨has, hs⟩ t ⟨hat, ht⟩, ⟨s ∩ t, ⟨⟨has, hat⟩, is_open_inter hs ht⟩,
⟨inter_subset_left _ _, inter_subset_right _ _⟩⟩)
⟨univ, ⟨mem_univ a, is_open_univ⟩⟩
end
/-- A filter lies below the neighborhood filter at `a` iff it contains every open set around `a`. -/
lemma le_nhds_iff {f a} : f ≤ 𝓝 a ↔ ∀ s : set α, a ∈ s → is_open s → s ∈ f :=
by simp [nhds_def]
/-- To show a filter is above the neighborhood filter at `a`, it suffices to show that it is above
the principal filter of some open set `s` containing `a`. -/
lemma nhds_le_of_le {f a} {s : set α} (h : a ∈ s) (o : is_open s) (sf : 𝓟 s ≤ f) : 𝓝 a ≤ f :=
by rw nhds_def; exact infi_le_of_le s (infi_le_of_le ⟨h, o⟩ sf)
lemma mem_nhds_sets_iff {a : α} {s : set α} :
s ∈ 𝓝 a ↔ ∃t⊆s, is_open t ∧ a ∈ t :=
(nhds_basis_opens a).mem_iff.trans
⟨λ ⟨t, ⟨hat, ht⟩, hts⟩, ⟨t, hts, ht, hat⟩, λ ⟨t, hts, ht, hat⟩, ⟨t, ⟨hat, ht⟩, hts⟩⟩
/-- A predicate is true in a neighborhood of `a` iff it is true for all the points in an open set
containing `a`. -/
lemma eventually_nhds_iff {a : α} {p : α → Prop} :
(∀ᶠ x in 𝓝 a, p x) ↔ ∃ (t : set α), (∀ x ∈ t, p x) ∧ is_open t ∧ a ∈ t :=
mem_nhds_sets_iff.trans $ by simp only [subset_def, exists_prop, mem_set_of_eq]
lemma map_nhds {a : α} {f : α → β} :
map f (𝓝 a) = (⨅ s ∈ {s : set α | a ∈ s ∧ is_open s}, 𝓟 (image f s)) :=
((nhds_basis_opens a).map f).eq_binfi
lemma mem_of_nhds {a : α} {s : set α} : s ∈ 𝓝 a → a ∈ s :=
λ H, let ⟨t, ht, _, hs⟩ := mem_nhds_sets_iff.1 H in ht hs
/-- If a predicate is true in a neighborhood of `a`, then it is true for `a`. -/
lemma filter.eventually.self_of_nhds {p : α → Prop} {a : α}
(h : ∀ᶠ y in 𝓝 a, p y) : p a :=
mem_of_nhds h
lemma mem_nhds_sets {a : α} {s : set α} (hs : is_open s) (ha : a ∈ s) :
s ∈ 𝓝 a :=
mem_nhds_sets_iff.2 ⟨s, subset.refl _, hs, ha⟩
lemma is_open.eventually_mem {a : α} {s : set α} (hs : is_open s) (ha : a ∈ s) :
∀ᶠ x in 𝓝 a, x ∈ s :=
mem_nhds_sets hs ha
/-- The open neighborhoods of `a` are a basis for the neighborhood filter. See `nhds_basis_opens`
for a variant using open sets around `a` instead. -/
lemma nhds_basis_opens' (a : α) : (𝓝 a).has_basis (λ s : set α, s ∈ 𝓝 a ∧ is_open s) (λ x, x) :=
begin
convert nhds_basis_opens a,
ext s,
split,
{ rintros ⟨s_in, s_op⟩,
exact ⟨mem_of_nhds s_in, s_op⟩ },
{ rintros ⟨a_in, s_op⟩,
exact ⟨mem_nhds_sets s_op a_in, s_op⟩ },
end
/-- If a predicate is true in a neighbourhood of `a`, then for `y` sufficiently close
to `a` this predicate is true in a neighbourhood of `y`. -/
lemma filter.eventually.eventually_nhds {p : α → Prop} {a : α} (h : ∀ᶠ y in 𝓝 a, p y) :
∀ᶠ y in 𝓝 a, ∀ᶠ x in 𝓝 y, p x :=
let ⟨t, htp, hto, ha⟩ := eventually_nhds_iff.1 h in
eventually_nhds_iff.2 ⟨t, λ x hx, eventually_nhds_iff.2 ⟨t, htp, hto, hx⟩, hto, ha⟩
@[simp] lemma eventually_eventually_nhds {p : α → Prop} {a : α} :
(∀ᶠ y in 𝓝 a, ∀ᶠ x in 𝓝 y, p x) ↔ ∀ᶠ x in 𝓝 a, p x :=
⟨λ h, h.self_of_nhds, λ h, h.eventually_nhds⟩
@[simp] lemma nhds_bind_nhds : (𝓝 a).bind 𝓝 = 𝓝 a := filter.ext $ λ s, eventually_eventually_nhds
@[simp] lemma eventually_eventually_eq_nhds {f g : α → β} {a : α} :
(∀ᶠ y in 𝓝 a, f =ᶠ[𝓝 y] g) ↔ f =ᶠ[𝓝 a] g :=
eventually_eventually_nhds
lemma filter.eventually_eq.eq_of_nhds {f g : α → β} {a : α} (h : f =ᶠ[𝓝 a] g) : f a = g a :=
h.self_of_nhds
@[simp] lemma eventually_eventually_le_nhds [has_le β] {f g : α → β} {a : α} :
(∀ᶠ y in 𝓝 a, f ≤ᶠ[𝓝 y] g) ↔ f ≤ᶠ[𝓝 a] g :=
eventually_eventually_nhds
/-- If two functions are equal in a neighbourhood of `a`, then for `y` sufficiently close
to `a` these functions are equal in a neighbourhood of `y`. -/
lemma filter.eventually_eq.eventually_eq_nhds {f g : α → β} {a : α} (h : f =ᶠ[𝓝 a] g) :
∀ᶠ y in 𝓝 a, f =ᶠ[𝓝 y] g :=
h.eventually_nhds
/-- If `f x ≤ g x` in a neighbourhood of `a`, then for `y` sufficiently close to `a` we have
`f x ≤ g x` in a neighbourhood of `y`. -/
lemma filter.eventually_le.eventually_le_nhds [has_le β] {f g : α → β} {a : α} (h : f ≤ᶠ[𝓝 a] g) :
∀ᶠ y in 𝓝 a, f ≤ᶠ[𝓝 y] g :=
h.eventually_nhds
theorem all_mem_nhds (x : α) (P : set α → Prop) (hP : ∀ s t, s ⊆ t → P s → P t) :
(∀ s ∈ 𝓝 x, P s) ↔ (∀ s, is_open s → x ∈ s → P s) :=
((nhds_basis_opens x).forall_iff hP).trans $ by simp only [and_comm (x ∈ _), and_imp]
theorem all_mem_nhds_filter (x : α) (f : set α → set β) (hf : ∀ s t, s ⊆ t → f s ⊆ f t)
(l : filter β) :
(∀ s ∈ 𝓝 x, f s ∈ l) ↔ (∀ s, is_open s → x ∈ s → f s ∈ l) :=
all_mem_nhds _ _ (λ s t ssubt h, mem_sets_of_superset h (hf s t ssubt))
theorem rtendsto_nhds {r : rel β α} {l : filter β} {a : α} :
rtendsto r l (𝓝 a) ↔ (∀ s, is_open s → a ∈ s → r.core s ∈ l) :=
all_mem_nhds_filter _ _ (λ s t, id) _
theorem rtendsto'_nhds {r : rel β α} {l : filter β} {a : α} :
rtendsto' r l (𝓝 a) ↔ (∀ s, is_open s → a ∈ s → r.preimage s ∈ l) :=
by { rw [rtendsto'_def], apply all_mem_nhds_filter, apply rel.preimage_mono }
theorem ptendsto_nhds {f : β →. α} {l : filter β} {a : α} :
ptendsto f l (𝓝 a) ↔ (∀ s, is_open s → a ∈ s → f.core s ∈ l) :=
rtendsto_nhds
theorem ptendsto'_nhds {f : β →. α} {l : filter β} {a : α} :
ptendsto' f l (𝓝 a) ↔ (∀ s, is_open s → a ∈ s → f.preimage s ∈ l) :=
rtendsto'_nhds
theorem tendsto_nhds {f : β → α} {l : filter β} {a : α} :
tendsto f l (𝓝 a) ↔ (∀ s, is_open s → a ∈ s → f ⁻¹' s ∈ l) :=
all_mem_nhds_filter _ _ (λ s t h, preimage_mono h) _
lemma tendsto_const_nhds {a : α} {f : filter β} : tendsto (λb:β, a) f (𝓝 a) :=
tendsto_nhds.mpr $ assume s hs ha, univ_mem_sets' $ assume _, ha
lemma pure_le_nhds : pure ≤ (𝓝 : α → filter α) :=
assume a s hs, mem_pure_sets.2 $ mem_of_nhds hs
lemma tendsto_pure_nhds {α : Type*} [topological_space β] (f : α → β) (a : α) :
tendsto f (pure a) (𝓝 (f a)) :=
(tendsto_pure_pure f a).mono_right (pure_le_nhds _)
lemma order_top.tendsto_at_top_nhds {α : Type*} [order_top α] [topological_space β] (f : α → β) :
tendsto f at_top (𝓝 $ f ⊤) :=
(tendsto_at_top_pure f).mono_right (pure_le_nhds _)
@[simp] instance nhds_ne_bot {a : α} : ne_bot (𝓝 a) :=
ne_bot_of_le (pure_le_nhds a)
/-!
### Cluster points
In this section we define [cluster points](https://en.wikipedia.org/wiki/Limit_point)
(also known as limit points and accumulation points) of a filter and of a sequence.
-/
/-- A point `x` is a cluster point of a filter `F` if 𝓝 x ⊓ F ≠ ⊥. Also known as
an accumulation point or a limit point. -/
def cluster_pt (x : α) (F : filter α) : Prop := ne_bot (𝓝 x ⊓ F)
lemma cluster_pt.ne_bot {x : α} {F : filter α} (h : cluster_pt x F) : ne_bot (𝓝 x ⊓ F) := h
lemma filter.has_basis.cluster_pt_iff {ιa ιF} {pa : ιa → Prop} {sa : ιa → set α}
{pF : ιF → Prop} {sF : ιF → set α} {F : filter α}
(ha : (𝓝 a).has_basis pa sa) (hF : F.has_basis pF sF) :
cluster_pt a F ↔ ∀ ⦃i⦄ (hi : pa i) ⦃j⦄ (hj : pF j), (sa i ∩ sF j).nonempty :=
ha.inf_basis_ne_bot_iff hF
lemma cluster_pt_iff {x : α} {F : filter α} :
cluster_pt x F ↔ ∀ ⦃U : set α⦄ (hU : U ∈ 𝓝 x) ⦃V⦄ (hV : V ∈ F), (U ∩ V).nonempty :=
inf_ne_bot_iff
/-- `x` is a cluster point of a set `s` if every neighbourhood of `x` meets `s` on a nonempty
set. -/
lemma cluster_pt_principal_iff {x : α} {s : set α} :
cluster_pt x (𝓟 s) ↔ ∀ U ∈ 𝓝 x, (U ∩ s).nonempty :=
inf_principal_ne_bot_iff
lemma cluster_pt_principal_iff_frequently {x : α} {s : set α} :
cluster_pt x (𝓟 s) ↔ ∃ᶠ y in 𝓝 x, y ∈ s :=
by simp only [cluster_pt_principal_iff, frequently_iff, set.nonempty, exists_prop, mem_inter_iff]
lemma cluster_pt.of_le_nhds {x : α} {f : filter α} (H : f ≤ 𝓝 x) [ne_bot f] : cluster_pt x f :=
by rwa [cluster_pt, inf_eq_right.mpr H]
lemma cluster_pt.of_le_nhds' {x : α} {f : filter α} (H : f ≤ 𝓝 x) (hf : ne_bot f) :
cluster_pt x f :=
cluster_pt.of_le_nhds H
lemma cluster_pt.of_nhds_le {x : α} {f : filter α} (H : 𝓝 x ≤ f) : cluster_pt x f :=
by simp only [cluster_pt, inf_eq_left.mpr H, nhds_ne_bot]
lemma cluster_pt.mono {x : α} {f g : filter α} (H : cluster_pt x f) (h : f ≤ g) :
cluster_pt x g :=
⟨ne_bot_of_le_ne_bot H.ne $ inf_le_inf_left _ h⟩
lemma cluster_pt.of_inf_left {x : α} {f g : filter α} (H : cluster_pt x $ f ⊓ g) :
cluster_pt x f :=
H.mono inf_le_left
lemma cluster_pt.of_inf_right {x : α} {f g : filter α} (H : cluster_pt x $ f ⊓ g) :
cluster_pt x g :=
H.mono inf_le_right
lemma ultrafilter.cluster_pt_iff {x : α} {f : ultrafilter α} : cluster_pt x f ↔ ↑f ≤ 𝓝 x :=
⟨f.le_of_inf_ne_bot', λ h, cluster_pt.of_le_nhds h⟩
/-- A point `x` is a cluster point of a sequence `u` along a filter `F` if it is a cluster point
of `map u F`. -/
def map_cluster_pt {ι :Type*} (x : α) (F : filter ι) (u : ι → α) : Prop := cluster_pt x (map u F)
lemma map_cluster_pt_iff {ι :Type*} (x : α) (F : filter ι) (u : ι → α) :
map_cluster_pt x F u ↔ ∀ s ∈ 𝓝 x, ∃ᶠ a in F, u a ∈ s :=
by { simp_rw [map_cluster_pt, cluster_pt, inf_ne_bot_iff_frequently_left, frequently_map], refl }
lemma map_cluster_pt_of_comp {ι δ :Type*} {F : filter ι} {φ : δ → ι} {p : filter δ}
{x : α} {u : ι → α} [ne_bot p] (h : tendsto φ p F) (H : tendsto (u ∘ φ) p (𝓝 x)) :
map_cluster_pt x F u :=
begin
have := calc
map (u ∘ φ) p = map u (map φ p) : map_map
... ≤ map u F : map_mono h,
have : map (u ∘ φ) p ≤ 𝓝 x ⊓ map u F,
from le_inf H this,
exact ne_bot_of_le this
end
/-!
### Interior, closure and frontier in terms of neighborhoods
-/
lemma interior_eq_nhds' {s : set α} : interior s = {a | s ∈ 𝓝 a} :=
set.ext $ λ x, by simp only [mem_interior, mem_nhds_sets_iff, mem_set_of_eq]
lemma interior_eq_nhds {s : set α} : interior s = {a | 𝓝 a ≤ 𝓟 s} :=
interior_eq_nhds'.trans $ by simp only [le_principal_iff]
lemma mem_interior_iff_mem_nhds {s : set α} {a : α} :
a ∈ interior s ↔ s ∈ 𝓝 a :=
by rw [interior_eq_nhds', mem_set_of_eq]
@[simp] lemma interior_mem_nhds {s : set α} {a : α} :
interior s ∈ 𝓝 a ↔ s ∈ 𝓝 a :=
⟨λ h, mem_sets_of_superset h interior_subset,
λ h, mem_nhds_sets is_open_interior (mem_interior_iff_mem_nhds.2 h)⟩
lemma interior_set_of_eq {p : α → Prop} :
interior {x | p x} = {x | ∀ᶠ y in 𝓝 x, p y} :=
interior_eq_nhds'
lemma is_open_set_of_eventually_nhds {p : α → Prop} :
is_open {x | ∀ᶠ y in 𝓝 x, p y} :=
by simp only [← interior_set_of_eq, is_open_interior]
lemma subset_interior_iff_nhds {s V : set α} : s ⊆ interior V ↔ ∀ x ∈ s, V ∈ 𝓝 x :=
show (∀ x, x ∈ s → x ∈ _) ↔ _, by simp_rw mem_interior_iff_mem_nhds
lemma is_open_iff_nhds {s : set α} : is_open s ↔ ∀a∈s, 𝓝 a ≤ 𝓟 s :=
calc is_open s ↔ s ⊆ interior s : subset_interior_iff_open.symm
... ↔ (∀a∈s, 𝓝 a ≤ 𝓟 s) : by rw [interior_eq_nhds]; refl
lemma is_open_iff_mem_nhds {s : set α} : is_open s ↔ ∀a∈s, s ∈ 𝓝 a :=
is_open_iff_nhds.trans $ forall_congr $ λ _, imp_congr_right $ λ _, le_principal_iff
theorem is_open_iff_ultrafilter {s : set α} :
is_open s ↔ (∀ (x ∈ s) (l : ultrafilter α), ↑l ≤ 𝓝 x → s ∈ l) :=
by simp_rw [is_open_iff_mem_nhds, ← mem_iff_ultrafilter]
lemma mem_closure_iff_frequently {s : set α} {a : α} : a ∈ closure s ↔ ∃ᶠ x in 𝓝 a, x ∈ s :=
by rw [filter.frequently, filter.eventually, ← mem_interior_iff_mem_nhds,
closure_eq_compl_interior_compl]; refl
alias mem_closure_iff_frequently ↔ _ filter.frequently.mem_closure
/-- The set of cluster points of a filter is closed. In particular, the set of limit points
of a sequence is closed. -/
lemma is_closed_set_of_cluster_pt {f : filter α} : is_closed {x | cluster_pt x f} :=
begin
simp only [cluster_pt, inf_ne_bot_iff_frequently_left, set_of_forall, imp_iff_not_or],
refine is_closed_Inter (λ p, is_closed_union _ _); apply is_closed_compl_iff.2,
exacts [is_open_set_of_eventually_nhds, is_open_const]
end
theorem mem_closure_iff_cluster_pt {s : set α} {a : α} : a ∈ closure s ↔ cluster_pt a (𝓟 s) :=
mem_closure_iff_frequently.trans cluster_pt_principal_iff_frequently.symm
lemma mem_closure_iff_nhds_ne_bot {s : set α} : a ∈ closure s ↔ 𝓝 a ⊓ 𝓟 s ≠ ⊥ :=
mem_closure_iff_cluster_pt.trans ne_bot_iff
lemma closure_eq_cluster_pts {s : set α} : closure s = {a | cluster_pt a (𝓟 s)} :=
set.ext $ λ x, mem_closure_iff_cluster_pt
theorem mem_closure_iff_nhds {s : set α} {a : α} :
a ∈ closure s ↔ ∀ t ∈ 𝓝 a, (t ∩ s).nonempty :=
mem_closure_iff_cluster_pt.trans cluster_pt_principal_iff
theorem mem_closure_iff_nhds' {s : set α} {a : α} :
a ∈ closure s ↔ ∀ t ∈ 𝓝 a, ∃ y : s, ↑y ∈ t :=
by simp only [mem_closure_iff_nhds, set.nonempty_inter_iff_exists_right]
theorem mem_closure_iff_comap_ne_bot {A : set α} {x : α} :
x ∈ closure A ↔ ne_bot (comap (coe : A → α) (𝓝 x)) :=
by simp_rw [mem_closure_iff_nhds, comap_ne_bot_iff, set.nonempty_inter_iff_exists_right]
theorem mem_closure_iff_nhds_basis' {a : α} {p : β → Prop} {s : β → set α} (h : (𝓝 a).has_basis p s)
{t : set α} :
a ∈ closure t ↔ ∀ i, p i → (s i ∩ t).nonempty :=
mem_closure_iff_cluster_pt.trans $ (h.cluster_pt_iff (has_basis_principal _)).trans $
by simp only [exists_prop, forall_const]
theorem mem_closure_iff_nhds_basis {a : α} {p : β → Prop} {s : β → set α} (h : (𝓝 a).has_basis p s)
{t : set α} :
a ∈ closure t ↔ ∀ i, p i → ∃ y ∈ t, y ∈ s i :=
(mem_closure_iff_nhds_basis' h).trans $
by simp only [set.nonempty, mem_inter_eq, exists_prop, and_comm]
/-- `x` belongs to the closure of `s` if and only if some ultrafilter
supported on `s` converges to `x`. -/
lemma mem_closure_iff_ultrafilter {s : set α} {x : α} :
x ∈ closure s ↔ ∃ (u : ultrafilter α), s ∈ u ∧ ↑u ≤ 𝓝 x :=
by simp [closure_eq_cluster_pts, cluster_pt, ← exists_ultrafilter_iff, and.comm]
lemma is_closed_iff_cluster_pt {s : set α} : is_closed s ↔ ∀a, cluster_pt a (𝓟 s) → a ∈ s :=
calc is_closed s ↔ closure s ⊆ s : closure_subset_iff_is_closed.symm
... ↔ (∀a, cluster_pt a (𝓟 s) → a ∈ s) : by simp only [subset_def, mem_closure_iff_cluster_pt]
lemma is_closed_iff_nhds {s : set α} : is_closed s ↔ ∀ x, (∀ U ∈ 𝓝 x, (U ∩ s).nonempty) → x ∈ s :=
by simp_rw [is_closed_iff_cluster_pt, cluster_pt, inf_principal_ne_bot_iff]
lemma closure_inter_open {s t : set α} (h : is_open s) : s ∩ closure t ⊆ closure (s ∩ t) :=
begin
rintro a ⟨hs, ht⟩,
have : s ∈ 𝓝 a := mem_nhds_sets h hs,
rw mem_closure_iff_nhds_ne_bot at ht ⊢,
rwa [← inf_principal, ← inf_assoc, inf_eq_left.2 (le_principal_iff.2 this)],
end
lemma closure_inter_open' {s t : set α} (h : is_open t) : closure s ∩ t ⊆ closure (s ∩ t) :=
by simpa only [inter_comm] using closure_inter_open h
/-- The intersection of an open dense set with a dense set is a dense set. -/
lemma dense.inter_of_open_left {s t : set α} (hs : dense s) (ht : dense t) (hso : is_open s) :
dense (s ∩ t) :=
λ x, (closure_minimal (closure_inter_open hso) is_closed_closure) $
by simp [hs.closure_eq, ht.closure_eq]
/-- The intersection of a dense set with an open dense set is a dense set. -/
lemma dense.inter_of_open_right {s t : set α} (hs : dense s) (ht : dense t) (hto : is_open t) :
dense (s ∩ t) :=
inter_comm t s ▸ ht.inter_of_open_left hs hto
lemma dense.inter_nhds_nonempty {s t : set α} (hs : dense s) {x : α} (ht : t ∈ 𝓝 x) :
(s ∩ t).nonempty :=
let ⟨U, hsub, ho, hx⟩ := mem_nhds_sets_iff.1 ht in
(hs.inter_open_nonempty U ho ⟨x, hx⟩).mono $ λ y hy, ⟨hy.2, hsub hy.1⟩
lemma closure_diff {s t : set α} : closure s \ closure t ⊆ closure (s \ t) :=
calc closure s \ closure t = (closure t)ᶜ ∩ closure s : by simp only [diff_eq, inter_comm]
... ⊆ closure ((closure t)ᶜ ∩ s) : closure_inter_open $ is_open_compl_iff.mpr $ is_closed_closure
... = closure (s \ closure t) : by simp only [diff_eq, inter_comm]
... ⊆ closure (s \ t) : closure_mono $ diff_subset_diff (subset.refl s) subset_closure
lemma filter.frequently.mem_of_closed {a : α} {s : set α} (h : ∃ᶠ x in 𝓝 a, x ∈ s)
(hs : is_closed s) : a ∈ s :=
hs.closure_subset h.mem_closure
lemma is_closed.mem_of_frequently_of_tendsto {f : β → α} {b : filter β} {a : α} {s : set α}
(hs : is_closed s) (h : ∃ᶠ x in b, f x ∈ s) (hf : tendsto f b (𝓝 a)) : a ∈ s :=
(hf.frequently $ show ∃ᶠ x in b, (λ y, y ∈ s) (f x), from h).mem_of_closed hs
lemma is_closed.mem_of_tendsto {f : β → α} {b : filter β} {a : α} {s : set α}
[ne_bot b] (hs : is_closed s) (hf : tendsto f b (𝓝 a)) (h : ∀ᶠ x in b, f x ∈ s) : a ∈ s :=
hs.mem_of_frequently_of_tendsto h.frequently hf
lemma mem_closure_of_tendsto {f : β → α} {b : filter β} {a : α} {s : set α}
[ne_bot b] (hf : tendsto f b (𝓝 a)) (h : ∀ᶠ x in b, f x ∈ s) : a ∈ closure s :=
is_closed_closure.mem_of_tendsto hf $ h.mono (preimage_mono subset_closure)
/-- Suppose that `f` sends the complement to `s` to a single point `a`, and `l` is some filter.
Then `f` tends to `a` along `l` restricted to `s` if and only if it tends to `a` along `l`. -/
lemma tendsto_inf_principal_nhds_iff_of_forall_eq {f : β → α} {l : filter β} {s : set β}
{a : α} (h : ∀ x ∉ s, f x = a) :
tendsto f (l ⊓ 𝓟 s) (𝓝 a) ↔ tendsto f l (𝓝 a) :=
begin
rw [tendsto_iff_comap, tendsto_iff_comap],
replace h : 𝓟 sᶜ ≤ comap f (𝓝 a),
{ rintros U ⟨t, ht, htU⟩ x hx,
have : f x ∈ t, from (h x hx).symm ▸ mem_of_nhds ht,
exact htU this },
refine ⟨λ h', _, le_trans inf_le_left⟩,
have := sup_le h' h,
rw [sup_inf_right, sup_principal, union_compl_self, principal_univ,
inf_top_eq, sup_le_iff] at this,
exact this.1
end
/-!
### Limits of filters in topological spaces
-/
section lim
/-- If `f` is a filter, then `Lim f` is a limit of the filter, if it exists. -/
noncomputable def Lim [nonempty α] (f : filter α) : α := epsilon $ λa, f ≤ 𝓝 a
/--
If `f` is a filter satisfying `ne_bot f`, then `Lim' f` is a limit of the filter, if it exists.
-/
def Lim' (f : filter α) [ne_bot f] : α := @Lim _ _ (nonempty_of_ne_bot f) f
/--
If `F` is an ultrafilter, then `filter.ultrafilter.Lim F` is a limit of the filter, if it exists.
Note that dot notation `F.Lim` can be used for `F : ultrafilter α`.
-/
def ultrafilter.Lim : ultrafilter α → α := λ F, Lim' F
/-- If `f` is a filter in `β` and `g : β → α` is a function, then `lim f` is a limit of `g` at `f`,
if it exists. -/
noncomputable def lim [nonempty α] (f : filter β) (g : β → α) : α :=
Lim (f.map g)
/-- If a filter `f` is majorated by some `𝓝 a`, then it is majorated by `𝓝 (Lim f)`. We formulate
this lemma with a `[nonempty α]` argument of `Lim` derived from `h` to make it useful for types
without a `[nonempty α]` instance. Because of the built-in proof irrelevance, Lean will unify
this instance with any other instance. -/
lemma le_nhds_Lim {f : filter α} (h : ∃a, f ≤ 𝓝 a) : f ≤ 𝓝 (@Lim _ _ (nonempty_of_exists h) f) :=
epsilon_spec h
/-- If `g` tends to some `𝓝 a` along `f`, then it tends to `𝓝 (lim f g)`. We formulate
this lemma with a `[nonempty α]` argument of `lim` derived from `h` to make it useful for types
without a `[nonempty α]` instance. Because of the built-in proof irrelevance, Lean will unify
this instance with any other instance. -/
lemma tendsto_nhds_lim {f : filter β} {g : β → α} (h : ∃ a, tendsto g f (𝓝 a)) :
tendsto g f (𝓝 $ @lim _ _ _ (nonempty_of_exists h) f g) :=
le_nhds_Lim h
end lim
/-!
### Locally finite families
-/
/- locally finite family [General Topology (Bourbaki, 1995)] -/
section locally_finite
/-- A family of sets in `set α` is locally finite if at every point `x:α`,
there is a neighborhood of `x` which meets only finitely many sets in the family -/
def locally_finite (f : β → set α) :=
∀x:α, ∃t ∈ 𝓝 x, finite {i | (f i ∩ t).nonempty }
lemma locally_finite.point_finite {f : β → set α} (hf : locally_finite f) (x : α) :
finite {b | x ∈ f b} :=
let ⟨t, hxt, ht⟩ := hf x in ht.subset $ λ b hb, ⟨x, hb, mem_of_nhds hxt⟩
lemma locally_finite_of_fintype [fintype β] (f : β → set α) : locally_finite f :=
assume x, ⟨univ, univ_mem_sets, finite.of_fintype _⟩
lemma locally_finite.subset
{f₁ f₂ : β → set α} (hf₂ : locally_finite f₂) (hf : ∀b, f₁ b ⊆ f₂ b) : locally_finite f₁ :=
assume a,
let ⟨t, ht₁, ht₂⟩ := hf₂ a in
⟨t, ht₁, ht₂.subset $ assume i hi, hi.mono $ inter_subset_inter (hf i) $ subset.refl _⟩
lemma locally_finite.comp_injective {ι} {f : β → set α} {g : ι → β} (hf : locally_finite f)
(hg : function.injective g) : locally_finite (f ∘ g) :=
λ x, let ⟨t, htx, htf⟩ := hf x in ⟨t, htx, htf.preimage (hg.inj_on _)⟩
lemma locally_finite.closure {f : β → set α} (hf : locally_finite f) :
locally_finite (λ i, closure (f i)) :=
begin
intro x,
rcases hf x with ⟨s, hsx, hsf⟩,
refine ⟨interior s, interior_mem_nhds.2 hsx, hsf.subset $ λ i hi, _⟩,
exact (hi.mono (closure_inter_open' is_open_interior)).of_closure.mono
(inter_subset_inter_right _ interior_subset)
end
lemma locally_finite.is_closed_Union {f : β → set α}
(h₁ : locally_finite f) (h₂ : ∀i, is_closed (f i)) : is_closed (⋃i, f i) :=
is_open_compl_iff.1 $ is_open_iff_nhds.mpr $ assume a, assume h : a ∉ (⋃i, f i),
have ∀i, a ∈ (f i)ᶜ,
from assume i hi, h $ mem_Union.2 ⟨i, hi⟩,
have ∀i, (f i)ᶜ ∈ (𝓝 a),
by simp only [mem_nhds_sets_iff]; exact assume i,
⟨(f i)ᶜ, subset.refl _, (h₂ i).is_open_compl, this i⟩,
let ⟨t, h_sets, (h_fin : finite {i | (f i ∩ t).nonempty })⟩ := h₁ a in
calc 𝓝 a ≤ 𝓟 (t ∩ (⋂ i∈{i | (f i ∩ t).nonempty }, (f i)ᶜ)) : by simp *
... ≤ 𝓟 (⋃i, f i)ᶜ :
begin
simp only [principal_mono, subset_def, mem_compl_eq, mem_inter_eq,
mem_Inter, mem_set_of_eq, mem_Union, and_imp, not_exists,
exists_imp_distrib, ne_empty_iff_nonempty, set.nonempty],
exact assume x xt ht i xfi, ht i x xfi xt xfi
end
lemma locally_finite.closure_Union {f : β → set α} (h : locally_finite f) :
closure (⋃ i, f i) = ⋃ i, closure (f i) :=
subset.antisymm
(closure_minimal (Union_subset_Union $ λ _, subset_closure) $
h.closure.is_closed_Union $ λ _, is_closed_closure)
(Union_subset $ λ i, closure_mono $ subset_Union _ _)
end locally_finite
end topological_space
/-!
### Continuity
-/
section continuous
variables {α : Type*} {β : Type*} {γ : Type*} {δ : Type*}
variables [topological_space α] [topological_space β] [topological_space γ]
open_locale topological_space
/-- A function between topological spaces is continuous if the preimage
of every open set is open. Registered as a structure to make sure it is not unfolded by Lean. -/
structure continuous (f : α → β) : Prop :=
(is_open_preimage : ∀s, is_open s → is_open (f ⁻¹' s))
lemma continuous_def {f : α → β} : continuous f ↔ (∀s, is_open s → is_open (f ⁻¹' s)) :=
⟨λ hf s hs, hf.is_open_preimage s hs, λ h, ⟨h⟩⟩
lemma is_open.preimage {f : α → β} (hf : continuous f) {s : set β} (h : is_open s) :
is_open (f ⁻¹' s) :=
hf.is_open_preimage s h
/-- A function between topological spaces is continuous at a point `x₀`
if `f x` tends to `f x₀` when `x` tends to `x₀`. -/
def continuous_at (f : α → β) (x : α) := tendsto f (𝓝 x) (𝓝 (f x))
lemma continuous_at.tendsto {f : α → β} {x : α} (h : continuous_at f x) :
tendsto f (𝓝 x) (𝓝 (f x)) :=
h
lemma continuous_at_congr {f g : α → β} {x : α} (h : f =ᶠ[𝓝 x] g) :
continuous_at f x ↔ continuous_at g x :=
by simp only [continuous_at, tendsto_congr' h, h.eq_of_nhds]
lemma continuous_at.congr {f g : α → β} {x : α} (hf : continuous_at f x) (h : f =ᶠ[𝓝 x] g) :
continuous_at g x :=
(continuous_at_congr h).1 hf
lemma continuous_at.preimage_mem_nhds {f : α → β} {x : α} {t : set β} (h : continuous_at f x)
(ht : t ∈ 𝓝 (f x)) : f ⁻¹' t ∈ 𝓝 x :=
h ht
lemma cluster_pt.map {x : α} {la : filter α} {lb : filter β} (H : cluster_pt x la)
{f : α → β} (hfc : continuous_at f x) (hf : tendsto f la lb) :
cluster_pt (f x) lb :=
⟨ne_bot_of_le_ne_bot ((map_ne_bot_iff f).2 H).ne $ hfc.tendsto.inf hf⟩
lemma preimage_interior_subset_interior_preimage {f : α → β} {s : set β}
(hf : continuous f) : f⁻¹' (interior s) ⊆ interior (f⁻¹' s) :=
interior_maximal (preimage_mono interior_subset) (is_open_interior.preimage hf)
lemma continuous_id : continuous (id : α → α) :=
continuous_def.2 $ assume s h, h
lemma continuous.comp {g : β → γ} {f : α → β} (hg : continuous g) (hf : continuous f) :
continuous (g ∘ f) :=
continuous_def.2 $ assume s h, (h.preimage hg).preimage hf
lemma continuous.iterate {f : α → α} (h : continuous f) (n : ℕ) : continuous (f^[n]) :=
nat.rec_on n continuous_id (λ n ihn, ihn.comp h)
lemma continuous_at.comp {g : β → γ} {f : α → β} {x : α}
(hg : continuous_at g (f x)) (hf : continuous_at f x) :
continuous_at (g ∘ f) x :=
hg.comp hf
lemma continuous.tendsto {f : α → β} (hf : continuous f) (x) :
tendsto f (𝓝 x) (𝓝 (f x)) :=
((nhds_basis_opens x).tendsto_iff $ nhds_basis_opens $ f x).2 $
λ t ⟨hxt, ht⟩, ⟨f ⁻¹' t, ⟨hxt, ht.preimage hf⟩, subset.refl _⟩
/-- A version of `continuous.tendsto` that allows one to specify a simpler form of the limit.
E.g., one can write `continuous_exp.tendsto' 0 1 exp_zero`. -/
lemma continuous.tendsto' {f : α → β} (hf : continuous f) (x : α) (y : β) (h : f x = y) :
tendsto f (𝓝 x) (𝓝 y) :=
h ▸ hf.tendsto x
lemma continuous.continuous_at {f : α → β} {x : α} (h : continuous f) :
continuous_at f x :=
h.tendsto x
lemma continuous_iff_continuous_at {f : α → β} : continuous f ↔ ∀ x, continuous_at f x :=
⟨continuous.tendsto,
assume hf : ∀x, tendsto f (𝓝 x) (𝓝 (f x)),
continuous_def.2 $
assume s, assume hs : is_open s,
have ∀a, f a ∈ s → s ∈ 𝓝 (f a),
from λ a ha, mem_nhds_sets hs ha,
show is_open (f ⁻¹' s),
from is_open_iff_nhds.2 $ λ a ha, le_principal_iff.2 $ hf _ (this a ha)⟩
lemma continuous_at_const {x : α} {b : β} : continuous_at (λ a:α, b) x :=
tendsto_const_nhds
lemma continuous_const {b : β} : continuous (λa:α, b) :=
continuous_iff_continuous_at.mpr $ assume a, continuous_at_const
lemma continuous_at_id {x : α} : continuous_at id x :=
continuous_id.continuous_at
lemma continuous_at.iterate {f : α → α} {x : α} (hf : continuous_at f x) (hx : f x = x) (n : ℕ) :
continuous_at (f^[n]) x :=
nat.rec_on n continuous_at_id $ λ n ihn,
show continuous_at (f^[n] ∘ f) x,
from continuous_at.comp (hx.symm ▸ ihn) hf
lemma continuous_iff_is_closed {f : α → β} :
continuous f ↔ (∀s, is_closed s → is_closed (f ⁻¹' s)) :=
⟨assume hf s hs, by simpa using (continuous_def.1 hf sᶜ hs.is_open_compl).is_closed_compl,
assume hf, continuous_def.2 $ assume s,
by rw [←is_closed_compl_iff, ←is_closed_compl_iff]; exact hf _⟩
lemma is_closed.preimage {f : α → β} (hf : continuous f) {s : set β} (h : is_closed s) :
is_closed (f ⁻¹' s) :=
continuous_iff_is_closed.mp hf s h
lemma continuous_at_iff_ultrafilter {f : α → β} {x} : continuous_at f x ↔
∀ g : ultrafilter α, ↑g ≤ 𝓝 x → tendsto f g (𝓝 (f x)) :=
tendsto_iff_ultrafilter f (𝓝 x) (𝓝 (f x))
lemma continuous_iff_ultrafilter {f : α → β} :
continuous f ↔ ∀ x (g : ultrafilter α), ↑g ≤ 𝓝 x → tendsto f g (𝓝 (f x)) :=
by simp only [continuous_iff_continuous_at, continuous_at_iff_ultrafilter]
/-! ### Continuity and partial functions -/
/-- Continuity of a partial function -/
def pcontinuous (f : α →. β) := ∀ s, is_open s → is_open (f.preimage s)
lemma open_dom_of_pcontinuous {f : α →. β} (h : pcontinuous f) : is_open f.dom :=
by rw [←pfun.preimage_univ]; exact h _ is_open_univ
lemma pcontinuous_iff' {f : α →. β} :
pcontinuous f ↔ ∀ {x y} (h : y ∈ f x), ptendsto' f (𝓝 x) (𝓝 y) :=
begin
split,
{ intros h x y h',
simp only [ptendsto'_def, mem_nhds_sets_iff],
rintros s ⟨t, tsubs, opent, yt⟩,
exact ⟨f.preimage t, pfun.preimage_mono _ tsubs, h _ opent, ⟨y, yt, h'⟩⟩
},
intros hf s os,
rw is_open_iff_nhds,
rintros x ⟨y, ys, fxy⟩ t,
rw [mem_principal_sets],
assume h : f.preimage s ⊆ t,
change t ∈ 𝓝 x,
apply mem_sets_of_superset _ h,
have h' : ∀ s ∈ 𝓝 y, f.preimage s ∈ 𝓝 x,
{ intros s hs,
have : ptendsto' f (𝓝 x) (𝓝 y) := hf fxy,
rw ptendsto'_def at this,
exact this s hs },
show f.preimage s ∈ 𝓝 x,
apply h', rw mem_nhds_sets_iff, exact ⟨s, set.subset.refl _, os, ys⟩
end
/-- If a continuous map `f` maps `s` to `t`, then it maps `closure s` to `closure t`. -/
lemma set.maps_to.closure {s : set α} {t : set β} {f : α → β} (h : maps_to f s t)
(hc : continuous f) : maps_to f (closure s) (closure t) :=
begin
simp only [maps_to, mem_closure_iff_cluster_pt],
exact λ x hx, hx.map hc.continuous_at (tendsto_principal_principal.2 h)
end
lemma image_closure_subset_closure_image {f : α → β} {s : set α} (h : continuous f) :
f '' closure s ⊆ closure (f '' s) :=
((maps_to_image f s).closure h).image_subset
lemma map_mem_closure {s : set α} {t : set β} {f : α → β} {a : α}
(hf : continuous f) (ha : a ∈ closure s) (ht : ∀a∈s, f a ∈ t) : f a ∈ closure t :=
set.maps_to.closure ht hf ha
/-!
### Function with dense range
-/
section dense_range
variables {κ ι : Type*} (f : κ → β) (g : β → γ)
/-- `f : ι → β` has dense range if its range (image) is a dense subset of β. -/
def dense_range := dense (range f)
variables {f}
/-- A surjective map has dense range. -/
lemma function.surjective.dense_range (hf : function.surjective f) : dense_range f :=
λ x, by simp [hf.range_eq]
lemma dense_range_iff_closure_range : dense_range f ↔ closure (range f) = univ :=
dense_iff_closure_eq
lemma dense_range.closure_range (h : dense_range f) : closure (range f) = univ :=
h.closure_eq
lemma continuous.range_subset_closure_image_dense {f : α → β} (hf : continuous f)
{s : set α} (hs : dense s) :
range f ⊆ closure (f '' s) :=
by { rw [← image_univ, ← hs.closure_eq], exact image_closure_subset_closure_image hf }
/-- The image of a dense set under a continuous map with dense range is a dense set. -/
lemma dense_range.dense_image {f : α → β} (hf' : dense_range f) (hf : continuous f)
{s : set α} (hs : dense s) :
dense (f '' s) :=
(hf'.mono $ hf.range_subset_closure_image_dense hs).of_closure
/-- If a continuous map with dense range maps a dense set to a subset of `t`, then `t` is a dense
set. -/
lemma dense_range.dense_of_maps_to {f : α → β} (hf' : dense_range f) (hf : continuous f)
{s : set α} (hs : dense s) {t : set β} (ht : maps_to f s t) :
dense t :=
(hf'.dense_image hf hs).mono ht.image_subset
/-- Composition of a continuous map with dense range and a function with dense range has dense
range. -/
lemma dense_range.comp {g : β → γ} {f : κ → β} (hg : dense_range g) (hf : dense_range f)
(cg : continuous g) :
dense_range (g ∘ f) :=
by { rw [dense_range, range_comp], exact hg.dense_image cg hf }
lemma dense_range.nonempty_iff (hf : dense_range f) : nonempty κ ↔ nonempty β :=
range_nonempty_iff_nonempty.symm.trans hf.nonempty_iff
lemma dense_range.nonempty [h : nonempty β] (hf : dense_range f) : nonempty κ :=
hf.nonempty_iff.mpr h
/-- Given a function `f : α → β` with dense range and `b : β`, returns some `a : α`. -/
def dense_range.some (hf : dense_range f) (b : β) : κ :=
classical.choice $ hf.nonempty_iff.mpr ⟨b⟩
end dense_range
end continuous
|
c27817a48ba973f5de0ee6e3cbee5448728c39ee | 206422fb9edabf63def0ed2aa3f489150fb09ccb | /src/analysis/mean_inequalities.lean | 5f0ca9bcfbb75fc397ed572e37cec1385da794cd | [
"Apache-2.0"
] | permissive | hamdysalah1/mathlib | b915f86b2503feeae268de369f1b16932321f097 | 95454452f6b3569bf967d35aab8d852b1ddf8017 | refs/heads/master | 1,677,154,116,545 | 1,611,797,994,000 | 1,611,797,994,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 52,507 | lean | /-
Copyright (c) 2019 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov, Sébastien Gouëzel, Rémy Degenne
-/
import analysis.convex.specific_functions
import analysis.special_functions.pow
import data.real.conjugate_exponents
import tactic.nth_rewrite
import measure_theory.integration
/-!
# Mean value inequalities
In this file we prove several inequalities, including AM-GM inequality, Young's inequality,
Hölder inequality, and Minkowski inequality.
## Main theorems
### AM-GM inequality:
The inequality says that the geometric mean of a tuple of non-negative numbers is less than or equal
to their arithmetic mean. We prove the weighted version of this inequality: if $w$ and $z$
are two non-negative vectors and $\sum_{i\in s} w_i=1$, then
$$
\prod_{i\in s} z_i^{w_i} ≤ \sum_{i\in s} w_iz_i.
$$
The classical version is a special case of this inequality for $w_i=\frac{1}{n}$.
We prove a few versions of this inequality. Each of the following lemmas comes in two versions:
a version for real-valued non-negative functions is in the `real` namespace, and a version for
`nnreal`-valued functions is in the `nnreal` namespace.
- `geom_mean_le_arith_mean_weighted` : weighted version for functions on `finset`s;
- `geom_mean_le_arith_mean2_weighted` : weighted version for two numbers;
- `geom_mean_le_arith_mean3_weighted` : weighted version for three numbers;
- `geom_mean_le_arith_mean4_weighted` : weighted version for four numbers.
### Generalized mean inequality
The inequality says that for two non-negative vectors $w$ and $z$ with $\sum_{i\in s} w_i=1$
and $p ≤ q$ we have
$$
\sqrt[p]{\sum_{i\in s} w_i z_i^p} ≤ \sqrt[q]{\sum_{i\in s} w_i z_i^q}.
$$
Currently we only prove this inequality for $p=1$. As in the rest of `mathlib`, we provide
different theorems for natural exponents (`pow_arith_mean_le_arith_mean_pow`), integer exponents
(`fpow_arith_mean_le_arith_mean_fpow`), and real exponents (`rpow_arith_mean_le_arith_mean_rpow` and
`arith_mean_le_rpow_mean`). In the first two cases we prove
$$
\left(\sum_{i\in s} w_i z_i\right)^n ≤ \sum_{i\in s} w_i z_i^n
$$
in order to avoid using real exponents. For real exponents we prove both this and standard versions.
### Young's inequality
Young's inequality says that for non-negative numbers `a`, `b`, `p`, `q` such that
$\frac{1}{p}+\frac{1}{q}=1$ we have
$$
ab ≤ \frac{a^p}{p} + \frac{b^q}{q}.
$$
This inequality is a special case of the AM-GM inequality. It can be used to prove Hölder's
inequality (see below) but we use a different proof.
### Hölder's inequality
The inequality says that for two conjugate exponents `p` and `q` (i.e., for two positive numbers
such that $\frac{1}{p}+\frac{1}{q}=1$) and any two non-negative vectors their inner product is
less than or equal to the product of the $L_p$ norm of the first vector and the $L_q$ norm of the
second vector:
$$
\sum_{i\in s} a_ib_i ≤ \sqrt[p]{\sum_{i\in s} a_i^p}\sqrt[q]{\sum_{i\in s} b_i^q}.
$$
We give versions of this result in `real`, `nnreal` and `ennreal`.
There are at least two short proofs of this inequality. In one proof we prenormalize both vectors,
then apply Young's inequality to each $a_ib_i$. We use a different proof deducing this inequality
from the generalized mean inequality for well-chosen vectors and weights.
Hölder's inequality for the Lebesgue integral of ennreal and nnreal functions: we prove
`∫ (f * g) ∂μ ≤ (∫ f^p ∂μ) ^ (1/p) * (∫ g^q ∂μ) ^ (1/q)` for `p`, `q` conjugate real exponents
and `α→(e)nnreal` functions in two cases,
* `ennreal.lintegral_mul_le_Lp_mul_Lq` : ennreal functions,
* `nnreal.lintegral_mul_le_Lp_mul_Lq` : nnreal functions.
### Minkowski's inequality
The inequality says that for `p ≥ 1` the function
$$
\|a\|_p=\sqrt[p]{\sum_{i\in s} a_i^p}
$$
satisfies the triangle inequality $\|a+b\|_p\le \|a\|_p+\|b\|_p$.
We give versions of this result in `real`, `nnreal` and `ennreal`.
We deduce this inequality from Hölder's inequality. Namely, Hölder inequality implies that $\|a\|_p$
is the maximum of the inner product $\sum_{i\in s}a_ib_i$ over `b` such that $\|b\|_q\le 1$. Now
Minkowski's inequality follows from the fact that the maximum value of the sum of two functions is
less than or equal to the sum of the maximum values of the summands.
Minkowski's inequality for the Lebesgue integral of measurable functions with `ennreal` values:
we prove `(∫ (f + g)^p ∂μ) ^ (1/p) ≤ (∫ f^p ∂μ) ^ (1/p) + (∫ g^p ∂μ) ^ (1/p)` for `1 ≤ p`.
## TODO
- each inequality `A ≤ B` should come with a theorem `A = B ↔ _`; one of the ways to prove them
is to define `strict_convex_on` functions.
- generalized mean inequality with any `p ≤ q`, including negative numbers;
- prove that the power mean tends to the geometric mean as the exponent tends to zero.
- prove integral versions of these inequalities.
-/
universes u v
open finset
open_locale classical nnreal big_operators
noncomputable theory
variables {ι : Type u} (s : finset ι)
namespace real
/-- AM-GM inequality: the geometric mean is less than or equal to the arithmetic mean, weighted
version for real-valued nonnegative functions. -/
theorem geom_mean_le_arith_mean_weighted (w z : ι → ℝ) (hw : ∀ i ∈ s, 0 ≤ w i)
(hw' : ∑ i in s, w i = 1) (hz : ∀ i ∈ s, 0 ≤ z i) :
(∏ i in s, (z i) ^ (w i)) ≤ ∑ i in s, w i * z i :=
begin
-- If some number `z i` equals zero and has non-zero weight, then LHS is 0 and RHS is nonnegative.
by_cases A : ∃ i ∈ s, z i = 0 ∧ w i ≠ 0,
{ rcases A with ⟨i, his, hzi, hwi⟩,
rw [prod_eq_zero his],
{ exact sum_nonneg (λ j hj, mul_nonneg (hw j hj) (hz j hj)) },
{ rw hzi, exact zero_rpow hwi } },
-- If all numbers `z i` with non-zero weight are positive, then we apply Jensen's inequality
-- for `exp` and numbers `log (z i)` with weights `w i`.
{ simp only [not_exists, not_and, ne.def, not_not] at A,
have := convex_on_exp.map_sum_le hw hw' (λ i _, set.mem_univ $ log (z i)),
simp only [exp_sum, (∘), smul_eq_mul, mul_comm (w _) (log _)] at this,
convert this using 1; [apply prod_congr rfl, apply sum_congr rfl]; intros i hi,
{ cases eq_or_lt_of_le (hz i hi) with hz hz,
{ simp [A i hi hz.symm] },
{ exact rpow_def_of_pos hz _ } },
{ cases eq_or_lt_of_le (hz i hi) with hz hz,
{ simp [A i hi hz.symm] },
{ rw [exp_log hz] } } }
end
theorem pow_arith_mean_le_arith_mean_pow (w z : ι → ℝ) (hw : ∀ i ∈ s, 0 ≤ w i)
(hw' : ∑ i in s, w i = 1) (hz : ∀ i ∈ s, 0 ≤ z i) (n : ℕ) :
(∑ i in s, w i * z i) ^ n ≤ ∑ i in s, (w i * z i ^ n) :=
(convex_on_pow n).map_sum_le hw hw' hz
theorem pow_arith_mean_le_arith_mean_pow_of_even (w z : ι → ℝ) (hw : ∀ i ∈ s, 0 ≤ w i)
(hw' : ∑ i in s, w i = 1) {n : ℕ} (hn : even n) :
(∑ i in s, w i * z i) ^ n ≤ ∑ i in s, (w i * z i ^ n) :=
(convex_on_pow_of_even hn).map_sum_le hw hw' (λ _ _, trivial)
theorem fpow_arith_mean_le_arith_mean_fpow (w z : ι → ℝ) (hw : ∀ i ∈ s, 0 ≤ w i)
(hw' : ∑ i in s, w i = 1) (hz : ∀ i ∈ s, 0 < z i) (m : ℤ) :
(∑ i in s, w i * z i) ^ m ≤ ∑ i in s, (w i * z i ^ m) :=
(convex_on_fpow m).map_sum_le hw hw' hz
theorem rpow_arith_mean_le_arith_mean_rpow (w z : ι → ℝ) (hw : ∀ i ∈ s, 0 ≤ w i)
(hw' : ∑ i in s, w i = 1) (hz : ∀ i ∈ s, 0 ≤ z i) {p : ℝ} (hp : 1 ≤ p) :
(∑ i in s, w i * z i) ^ p ≤ ∑ i in s, (w i * z i ^ p) :=
(convex_on_rpow hp).map_sum_le hw hw' hz
theorem arith_mean_le_rpow_mean (w z : ι → ℝ) (hw : ∀ i ∈ s, 0 ≤ w i)
(hw' : ∑ i in s, w i = 1) (hz : ∀ i ∈ s, 0 ≤ z i) {p : ℝ} (hp : 1 ≤ p) :
∑ i in s, w i * z i ≤ (∑ i in s, (w i * z i ^ p)) ^ (1 / p) :=
begin
have : 0 < p := lt_of_lt_of_le zero_lt_one hp,
rw [← rpow_le_rpow_iff _ _ this, ← rpow_mul, one_div_mul_cancel (ne_of_gt this), rpow_one],
exact rpow_arith_mean_le_arith_mean_rpow s w z hw hw' hz hp,
all_goals { apply_rules [sum_nonneg, rpow_nonneg_of_nonneg],
intros i hi,
apply_rules [mul_nonneg, rpow_nonneg_of_nonneg, hw i hi, hz i hi] },
end
end real
namespace nnreal
/-- The geometric mean is less than or equal to the arithmetic mean, weighted version
for `nnreal`-valued functions. -/
theorem geom_mean_le_arith_mean_weighted (w z : ι → ℝ≥0) (hw' : ∑ i in s, w i = 1) :
(∏ i in s, (z i) ^ (w i:ℝ)) ≤ ∑ i in s, w i * z i :=
by exact_mod_cast real.geom_mean_le_arith_mean_weighted _ _ _ (λ i _, (w i).coe_nonneg)
(by assumption_mod_cast) (λ i _, (z i).coe_nonneg)
/-- The geometric mean is less than or equal to the arithmetic mean, weighted version
for two `nnreal` numbers. -/
theorem geom_mean_le_arith_mean2_weighted (w₁ w₂ p₁ p₂ : ℝ≥0) :
w₁ + w₂ = 1 → p₁ ^ (w₁:ℝ) * p₂ ^ (w₂:ℝ) ≤ w₁ * p₁ + w₂ * p₂ :=
by simpa only [fin.prod_univ_succ, fin.sum_univ_succ, fin.prod_univ_zero, fin.sum_univ_zero,
fin.cons_succ, fin.cons_zero, add_zero, mul_one]
using geom_mean_le_arith_mean_weighted (univ : finset (fin 2))
(fin.cons w₁ $ fin.cons w₂ fin_zero_elim) (fin.cons p₁ $ fin.cons p₂ $ fin_zero_elim)
theorem geom_mean_le_arith_mean3_weighted (w₁ w₂ w₃ p₁ p₂ p₃ : ℝ≥0) :
w₁ + w₂ + w₃ = 1 → p₁ ^ (w₁:ℝ) * p₂ ^ (w₂:ℝ) * p₃ ^ (w₃:ℝ) ≤ w₁ * p₁ + w₂ * p₂ + w₃ * p₃ :=
by simpa only [fin.prod_univ_succ, fin.sum_univ_succ, fin.prod_univ_zero, fin.sum_univ_zero,
fin.cons_succ, fin.cons_zero, add_zero, mul_one, ← add_assoc, mul_assoc]
using geom_mean_le_arith_mean_weighted (univ : finset (fin 3))
(fin.cons w₁ $ fin.cons w₂ $ fin.cons w₃ fin_zero_elim)
(fin.cons p₁ $ fin.cons p₂ $ fin.cons p₃ fin_zero_elim)
theorem geom_mean_le_arith_mean4_weighted (w₁ w₂ w₃ w₄ p₁ p₂ p₃ p₄ : ℝ≥0) :
w₁ + w₂ + w₃ + w₄ = 1 → p₁ ^ (w₁:ℝ) * p₂ ^ (w₂:ℝ) * p₃ ^ (w₃:ℝ)* p₄ ^ (w₄:ℝ) ≤
w₁ * p₁ + w₂ * p₂ + w₃ * p₃ + w₄ * p₄ :=
by simpa only [fin.prod_univ_succ, fin.sum_univ_succ, fin.prod_univ_zero, fin.sum_univ_zero,
fin.cons_succ, fin.cons_zero, add_zero, mul_one, ← add_assoc, mul_assoc]
using geom_mean_le_arith_mean_weighted (univ : finset (fin 4))
(fin.cons w₁ $ fin.cons w₂ $ fin.cons w₃ $ fin.cons w₄ fin_zero_elim)
(fin.cons p₁ $ fin.cons p₂ $ fin.cons p₃ $ fin.cons p₄ fin_zero_elim)
/-- Weighted generalized mean inequality, version sums over finite sets, with `ℝ≥0`-valued
functions and natural exponent. -/
theorem pow_arith_mean_le_arith_mean_pow (w z : ι → ℝ≥0) (hw' : ∑ i in s, w i = 1) (n : ℕ) :
(∑ i in s, w i * z i) ^ n ≤ ∑ i in s, (w i * z i ^ n) :=
by exact_mod_cast real.pow_arith_mean_le_arith_mean_pow s _ _ (λ i _, (w i).coe_nonneg)
(by exact_mod_cast hw') (λ i _, (z i).coe_nonneg) n
/-- Weighted generalized mean inequality, version for sums over finite sets, with `ℝ≥0`-valued
functions and real exponents. -/
theorem rpow_arith_mean_le_arith_mean_rpow (w z : ι → ℝ≥0) (hw' : ∑ i in s, w i = 1) {p : ℝ}
(hp : 1 ≤ p) :
(∑ i in s, w i * z i) ^ p ≤ ∑ i in s, (w i * z i ^ p) :=
by exact_mod_cast real.rpow_arith_mean_le_arith_mean_rpow s _ _ (λ i _, (w i).coe_nonneg)
(by exact_mod_cast hw') (λ i _, (z i).coe_nonneg) hp
/-- Weighted generalized mean inequality, version for two elements of `ℝ≥0` and real exponents. -/
theorem rpow_arith_mean_le_arith_mean2_rpow (w₁ w₂ z₁ z₂ : ℝ≥0) (hw' : w₁ + w₂ = 1) {p : ℝ}
(hp : 1 ≤ p) :
(w₁ * z₁ + w₂ * z₂) ^ p ≤ w₁ * z₁ ^ p + w₂ * z₂ ^ p :=
begin
have h := rpow_arith_mean_le_arith_mean_rpow (univ : finset (fin 2))
(fin.cons w₁ $ fin.cons w₂ fin_zero_elim) (fin.cons z₁ $ fin.cons z₂ $ fin_zero_elim) _ hp,
{ simpa [fin.sum_univ_succ, fin.sum_univ_zero, fin.cons_succ, fin.cons_zero] using h, },
{ simp [hw', fin.sum_univ_succ, fin.sum_univ_zero, fin.cons_succ, fin.cons_zero], },
end
/-- Weighted generalized mean inequality, version for sums over finite sets, with `ℝ≥0`-valued
functions and real exponents. -/
theorem arith_mean_le_rpow_mean (w z : ι → ℝ≥0) (hw' : ∑ i in s, w i = 1) {p : ℝ}
(hp : 1 ≤ p) :
∑ i in s, w i * z i ≤ (∑ i in s, (w i * z i ^ p)) ^ (1 / p) :=
by exact_mod_cast real.arith_mean_le_rpow_mean s _ _ (λ i _, (w i).coe_nonneg)
(by exact_mod_cast hw') (λ i _, (z i).coe_nonneg) hp
end nnreal
namespace ennreal
/-- Weighted generalized mean inequality, version for sums over finite sets, with `ennreal`-valued
functions and real exponents. -/
theorem rpow_arith_mean_le_arith_mean_rpow (w z : ι → ennreal) (hw' : ∑ i in s, w i = 1) {p : ℝ}
(hp : 1 ≤ p) :
(∑ i in s, w i * z i) ^ p ≤ ∑ i in s, (w i * z i ^ p) :=
begin
have hp_pos : 0 < p, from lt_of_lt_of_le zero_lt_one hp,
have hp_nonneg : 0 ≤ p, from le_of_lt hp_pos,
have hp_not_nonpos : ¬ p ≤ 0, by simp [hp_pos],
have hp_not_neg : ¬ p < 0, by simp [hp_nonneg],
have h_top_iff_rpow_top : ∀ (i : ι) (hi : i ∈ s), w i * z i = ⊤ ↔ w i * (z i) ^ p = ⊤,
by simp [hp_pos, hp_nonneg, hp_not_nonpos, hp_not_neg],
refine le_of_top_imp_top_of_to_nnreal_le _ _,
{ -- first, prove `(∑ i in s, w i * z i) ^ p = ⊤ → ∑ i in s, (w i * z i ^ p) = ⊤`
rw [rpow_eq_top_iff, sum_eq_top_iff, sum_eq_top_iff],
intro h,
simp only [and_false, hp_not_neg, false_or] at h,
rcases h.left with ⟨a, H, ha⟩,
use [a, H],
rwa ←h_top_iff_rpow_top a H, },
{ -- second, suppose both `(∑ i in s, w i * z i) ^ p ≠ ⊤` and `∑ i in s, (w i * z i ^ p) ≠ ⊤`,
-- and prove `((∑ i in s, w i * z i) ^ p).to_nnreal ≤ (∑ i in s, (w i * z i ^ p)).to_nnreal`,
-- by using `nnreal.rpow_arith_mean_le_arith_mean_rpow`.
intros h_top_rpow_sum _,
-- show hypotheses needed to put the `.to_nnreal` inside the sums.
have h_top : ∀ (a : ι), a ∈ s → w a * z a < ⊤,
{ have h_top_sum : ∑ (i : ι) in s, w i * z i < ⊤,
{ by_contra h,
rw [lt_top_iff_ne_top, not_not] at h,
rw [h, top_rpow_of_pos hp_pos] at h_top_rpow_sum,
exact h_top_rpow_sum rfl, },
rwa sum_lt_top_iff at h_top_sum, },
have h_top_rpow : ∀ (a : ι), a ∈ s → w a * z a ^ p < ⊤,
{ intros i hi,
specialize h_top i hi,
rw lt_top_iff_ne_top at h_top ⊢,
rwa [ne.def, ←h_top_iff_rpow_top i hi], },
-- put the `.to_nnreal` inside the sums.
simp_rw [to_nnreal_sum h_top_rpow, ←to_nnreal_rpow, to_nnreal_sum h_top, to_nnreal_mul,
←to_nnreal_rpow],
-- use corresponding nnreal result
refine nnreal.rpow_arith_mean_le_arith_mean_rpow s (λ i, (w i).to_nnreal) (λ i, (z i).to_nnreal)
_ hp,
-- verify the hypothesis `∑ i in s, (w i).to_nnreal = 1`, using `∑ i in s, w i = 1` .
have h_sum_nnreal : (∑ i in s, w i) = ↑(∑ i in s, (w i).to_nnreal),
{ have hw_top : ∑ i in s, w i < ⊤, by { rw hw', exact one_lt_top, },
rw ←to_nnreal_sum,
{ rw coe_to_nnreal,
rwa ←lt_top_iff_ne_top, },
{ rwa sum_lt_top_iff at hw_top, }, },
rwa [←coe_eq_coe, ←h_sum_nnreal], },
end
/-- Weighted generalized mean inequality, version for two elements of `ennreal` and real
exponents. -/
theorem rpow_arith_mean_le_arith_mean2_rpow (w₁ w₂ z₁ z₂ : ennreal) (hw' : w₁ + w₂ = 1) {p : ℝ}
(hp : 1 ≤ p) :
(w₁ * z₁ + w₂ * z₂) ^ p ≤ w₁ * z₁ ^ p + w₂ * z₂ ^ p :=
begin
have h := rpow_arith_mean_le_arith_mean_rpow (univ : finset (fin 2))
(fin.cons w₁ $ fin.cons w₂ fin_zero_elim) (fin.cons z₁ $ fin.cons z₂ $ fin_zero_elim) _ hp,
{ simpa [fin.sum_univ_succ, fin.sum_univ_zero, fin.cons_succ, fin.cons_zero] using h, },
{ simp [hw', fin.sum_univ_succ, fin.sum_univ_zero, fin.cons_succ, fin.cons_zero], },
end
end ennreal
namespace real
theorem geom_mean_le_arith_mean2_weighted {w₁ w₂ p₁ p₂ : ℝ} (hw₁ : 0 ≤ w₁) (hw₂ : 0 ≤ w₂)
(hp₁ : 0 ≤ p₁) (hp₂ : 0 ≤ p₂) (hw : w₁ + w₂ = 1) :
p₁ ^ w₁ * p₂ ^ w₂ ≤ w₁ * p₁ + w₂ * p₂ :=
nnreal.geom_mean_le_arith_mean2_weighted ⟨w₁, hw₁⟩ ⟨w₂, hw₂⟩ ⟨p₁, hp₁⟩ ⟨p₂, hp₂⟩ $
nnreal.coe_eq.1 $ by assumption
theorem geom_mean_le_arith_mean3_weighted {w₁ w₂ w₃ p₁ p₂ p₃ : ℝ} (hw₁ : 0 ≤ w₁) (hw₂ : 0 ≤ w₂)
(hw₃ : 0 ≤ w₃) (hp₁ : 0 ≤ p₁) (hp₂ : 0 ≤ p₂) (hp₃ : 0 ≤ p₃) (hw : w₁ + w₂ + w₃ = 1) :
p₁ ^ w₁ * p₂ ^ w₂ * p₃ ^ w₃ ≤ w₁ * p₁ + w₂ * p₂ + w₃ * p₃ :=
nnreal.geom_mean_le_arith_mean3_weighted
⟨w₁, hw₁⟩ ⟨w₂, hw₂⟩ ⟨w₃, hw₃⟩ ⟨p₁, hp₁⟩ ⟨p₂, hp₂⟩ ⟨p₃, hp₃⟩ $ nnreal.coe_eq.1 hw
theorem geom_mean_le_arith_mean4_weighted {w₁ w₂ w₃ w₄ p₁ p₂ p₃ p₄ : ℝ} (hw₁ : 0 ≤ w₁)
(hw₂ : 0 ≤ w₂) (hw₃ : 0 ≤ w₃) (hw₄ : 0 ≤ w₄) (hp₁ : 0 ≤ p₁) (hp₂ : 0 ≤ p₂) (hp₃ : 0 ≤ p₃)
(hp₄ : 0 ≤ p₄) (hw : w₁ + w₂ + w₃ + w₄ = 1) :
p₁ ^ w₁ * p₂ ^ w₂ * p₃ ^ w₃ * p₄ ^ w₄ ≤ w₁ * p₁ + w₂ * p₂ + w₃ * p₃ + w₄ * p₄ :=
nnreal.geom_mean_le_arith_mean4_weighted ⟨w₁, hw₁⟩ ⟨w₂, hw₂⟩ ⟨w₃, hw₃⟩ ⟨w₄, hw₄⟩
⟨p₁, hp₁⟩ ⟨p₂, hp₂⟩ ⟨p₃, hp₃⟩ ⟨p₄, hp₄⟩ $ nnreal.coe_eq.1 $ by assumption
/-- Young's inequality, a version for nonnegative real numbers. -/
theorem young_inequality_of_nonneg {a b p q : ℝ} (ha : 0 ≤ a) (hb : 0 ≤ b)
(hpq : p.is_conjugate_exponent q) :
a * b ≤ a^p / p + b^q / q :=
by simpa [← rpow_mul, ha, hb, hpq.ne_zero, hpq.symm.ne_zero, div_eq_inv_mul]
using geom_mean_le_arith_mean2_weighted hpq.one_div_nonneg hpq.symm.one_div_nonneg
(rpow_nonneg_of_nonneg ha p) (rpow_nonneg_of_nonneg hb q) hpq.inv_add_inv_conj
/-- Young's inequality, a version for arbitrary real numbers. -/
theorem young_inequality (a b : ℝ) {p q : ℝ} (hpq : p.is_conjugate_exponent q) :
a * b ≤ (abs a)^p / p + (abs b)^q / q :=
calc a * b ≤ abs (a * b) : le_abs_self (a * b)
... = abs a * abs b : abs_mul a b
... ≤ (abs a)^p / p + (abs b)^q / q :
real.young_inequality_of_nonneg (abs_nonneg a) (abs_nonneg b) hpq
end real
namespace nnreal
/-- Young's inequality, `ℝ≥0` version. We use `{p q : ℝ≥0}` in order to avoid constructing
witnesses of `0 ≤ p` and `0 ≤ q` for the denominators. -/
theorem young_inequality (a b : ℝ≥0) {p q : ℝ≥0} (hp : 1 < p) (hpq : 1 / p + 1 / q = 1) :
a * b ≤ a^(p:ℝ) / p + b^(q:ℝ) / q :=
real.young_inequality_of_nonneg a.coe_nonneg b.coe_nonneg ⟨hp, nnreal.coe_eq.2 hpq⟩
/-- Young's inequality, `ℝ≥0` version with real conjugate exponents. -/
theorem young_inequality_real (a b : ℝ≥0) {p q : ℝ} (hpq : p.is_conjugate_exponent q) :
a * b ≤ a ^ p / nnreal.of_real p + b ^ q / nnreal.of_real q :=
begin
nth_rewrite 0 ←coe_of_real p hpq.nonneg,
nth_rewrite 0 ←coe_of_real q hpq.symm.nonneg,
exact young_inequality a b hpq.one_lt_nnreal hpq.inv_add_inv_conj_nnreal,
end
/-- Hölder inequality: the scalar product of two functions is bounded by the product of their
`L^p` and `L^q` norms when `p` and `q` are conjugate exponents. Version for sums over finite sets,
with `ℝ≥0`-valued functions. -/
theorem inner_le_Lp_mul_Lq (f g : ι → ℝ≥0) {p q : ℝ}
(hpq : p.is_conjugate_exponent q) :
∑ i in s, f i * g i ≤ (∑ i in s, (f i) ^ p) ^ (1 / p) * (∑ i in s, (g i) ^ q) ^ (1 / q) :=
begin
-- Let `G=∥g∥_q` be the `L_q`-norm of `g`.
set G := (∑ i in s, (g i) ^ q) ^ (1 / q),
have hGq : G ^ q = ∑ i in s, (g i) ^ q,
{ rw [← rpow_mul, one_div_mul_cancel hpq.symm.ne_zero, rpow_one], },
-- First consider the trivial case `∥g∥_q=0`
by_cases hG : G = 0,
{ rw [hG, sum_eq_zero, mul_zero],
intros i hi,
simp only [rpow_eq_zero_iff, sum_eq_zero_iff] at hG,
simp [(hG.1 i hi).1] },
{ -- Move power from right to left
rw [← div_le_iff hG, sum_div],
-- Now the inequality follows from the weighted generalized mean inequality
-- with weights `w_i` and numbers `z_i` given by the following formulas.
set w : ι → ℝ≥0 := λ i, (g i) ^ q / G ^ q,
set z : ι → ℝ≥0 := λ i, f i * (G / g i) ^ (q / p),
-- Show that the sum of weights equals one
have A : ∑ i in s, w i = 1,
{ rw [← sum_div, hGq, div_self],
simpa [rpow_eq_zero_iff, hpq.symm.ne_zero] using hG },
-- LHS of the goal equals LHS of the weighted generalized mean inequality
calc (∑ i in s, f i * g i / G) = (∑ i in s, w i * z i) :
begin
refine sum_congr rfl (λ i hi, _),
have : q - q / p = 1, by field_simp [hpq.ne_zero, hpq.symm.mul_eq_add],
dsimp only [w, z],
rw [← div_rpow, mul_left_comm, mul_div_assoc, ← @inv_div _ _ _ G, inv_rpow,
← div_eq_mul_inv, ← rpow_sub']; simp [this]
end
-- Apply the generalized mean inequality
... ≤ (∑ i in s, w i * (z i) ^ p) ^ (1 / p) :
nnreal.arith_mean_le_rpow_mean s w z A (le_of_lt hpq.one_lt)
-- Simplify the right hand side. Terms with `g i ≠ 0` are equal to `(f i) ^ p`,
-- the others are zeros.
... ≤ (∑ i in s, (f i) ^ p) ^ (1 / p) :
begin
refine rpow_le_rpow (sum_le_sum (λ i hi, _)) hpq.one_div_nonneg,
dsimp only [w, z],
rw [mul_rpow, mul_left_comm, ← rpow_mul _ _ p, div_mul_cancel _ hpq.ne_zero, div_rpow,
div_mul_div, mul_comm (G ^ q), mul_div_mul_right],
{ nth_rewrite 1 [← mul_one ((f i) ^ p)],
exact canonically_ordered_semiring.mul_le_mul (le_refl _) (div_self_le _) },
{ simpa [hpq.symm.ne_zero] using hG }
end }
end
/-- The `L_p` seminorm of a vector `f` is the greatest value of the inner product
`∑ i in s, f i * g i` over functions `g` of `L_q` seminorm less than or equal to one. -/
theorem is_greatest_Lp (f : ι → ℝ≥0) {p q : ℝ} (hpq : p.is_conjugate_exponent q) :
is_greatest ((λ g : ι → ℝ≥0, ∑ i in s, f i * g i) ''
{g | ∑ i in s, (g i)^q ≤ 1}) ((∑ i in s, (f i)^p) ^ (1 / p)) :=
begin
split,
{ use λ i, ((f i) ^ p / f i / (∑ i in s, (f i) ^ p) ^ (1 / q)),
by_cases hf : ∑ i in s, (f i)^p = 0,
{ simp [hf, hpq.ne_zero, hpq.symm.ne_zero] },
{ have A : p + q - q ≠ 0, by simp [hpq.ne_zero],
have B : ∀ y : ℝ≥0, y * y^p / y = y^p,
{ refine λ y, mul_div_cancel_left_of_imp (λ h, _),
simpa [h, hpq.ne_zero] },
simp only [set.mem_set_of_eq, div_rpow, ← sum_div, ← rpow_mul,
div_mul_cancel _ hpq.symm.ne_zero, rpow_one, div_le_iff hf, one_mul, hpq.mul_eq_add,
← rpow_sub' _ A, _root_.add_sub_cancel, le_refl, true_and, ← mul_div_assoc, B],
rw [div_eq_iff, ← rpow_add hf, hpq.inv_add_inv_conj, rpow_one],
simpa [hpq.symm.ne_zero] using hf } },
{ rintros _ ⟨g, hg, rfl⟩,
apply le_trans (inner_le_Lp_mul_Lq s f g hpq),
simpa only [mul_one] using canonically_ordered_semiring.mul_le_mul (le_refl _)
(nnreal.rpow_le_one hg (le_of_lt hpq.symm.one_div_pos)) }
end
/-- Minkowski inequality: the `L_p` seminorm of the sum of two vectors is less than or equal
to the sum of the `L_p`-seminorms of the summands. A version for `nnreal`-valued functions. -/
theorem Lp_add_le (f g : ι → ℝ≥0) {p : ℝ} (hp : 1 ≤ p) :
(∑ i in s, (f i + g i) ^ p) ^ (1 / p) ≤
(∑ i in s, (f i) ^ p) ^ (1 / p) + (∑ i in s, (g i) ^ p) ^ (1 / p) :=
begin
-- The result is trivial when `p = 1`, so we can assume `1 < p`.
rcases eq_or_lt_of_le hp with rfl|hp, { simp [finset.sum_add_distrib] },
have hpq := real.is_conjugate_exponent_conjugate_exponent hp,
have := is_greatest_Lp s (f + g) hpq,
simp only [pi.add_apply, add_mul, sum_add_distrib] at this,
rcases this.1 with ⟨φ, hφ, H⟩,
rw ← H,
exact add_le_add ((is_greatest_Lp s f hpq).2 ⟨φ, hφ, rfl⟩)
((is_greatest_Lp s g hpq).2 ⟨φ, hφ, rfl⟩)
end
end nnreal
namespace real
variables (f g : ι → ℝ) {p q : ℝ}
/-- Hölder inequality: the scalar product of two functions is bounded by the product of their
`L^p` and `L^q` norms when `p` and `q` are conjugate exponents. Version for sums over finite sets,
with real-valued functions. -/
theorem inner_le_Lp_mul_Lq (hpq : is_conjugate_exponent p q) :
∑ i in s, f i * g i ≤ (∑ i in s, (abs $ f i)^p) ^ (1 / p) * (∑ i in s, (abs $ g i)^q) ^ (1 / q) :=
begin
have := nnreal.coe_le_coe.2 (nnreal.inner_le_Lp_mul_Lq s (λ i, ⟨_, abs_nonneg (f i)⟩)
(λ i, ⟨_, abs_nonneg (g i)⟩) hpq),
push_cast at this,
refine le_trans (sum_le_sum $ λ i hi, _) this,
simp only [← abs_mul, le_abs_self]
end
/-- Minkowski inequality: the `L_p` seminorm of the sum of two vectors is less than or equal
to the sum of the `L_p`-seminorms of the summands. A version for `real`-valued functions. -/
theorem Lp_add_le (hp : 1 ≤ p) :
(∑ i in s, (abs $ f i + g i) ^ p) ^ (1 / p) ≤
(∑ i in s, (abs $ f i) ^ p) ^ (1 / p) + (∑ i in s, (abs $ g i) ^ p) ^ (1 / p) :=
begin
have := nnreal.coe_le_coe.2 (nnreal.Lp_add_le s (λ i, ⟨_, abs_nonneg (f i)⟩)
(λ i, ⟨_, abs_nonneg (g i)⟩) hp),
push_cast at this,
refine le_trans (rpow_le_rpow _ (sum_le_sum $ λ i hi, _) _) this;
simp [sum_nonneg, rpow_nonneg_of_nonneg, abs_nonneg, le_trans zero_le_one hp, abs_add,
rpow_le_rpow]
end
variables {f g}
/-- Hölder inequality: the scalar product of two functions is bounded by the product of their
`L^p` and `L^q` norms when `p` and `q` are conjugate exponents. Version for sums over finite sets,
with real-valued nonnegative functions. -/
theorem inner_le_Lp_mul_Lq_of_nonneg (hpq : is_conjugate_exponent p q)
(hf : ∀ i ∈ s, 0 ≤ f i) (hg : ∀ i ∈ s, 0 ≤ g i) :
∑ i in s, f i * g i ≤ (∑ i in s, (f i)^p) ^ (1 / p) * (∑ i in s, (g i)^q) ^ (1 / q) :=
by convert inner_le_Lp_mul_Lq s f g hpq using 3; apply sum_congr rfl; intros i hi;
simp only [abs_of_nonneg, hf i hi, hg i hi]
/-- Minkowski inequality: the `L_p` seminorm of the sum of two vectors is less than or equal
to the sum of the `L_p`-seminorms of the summands. A version for `real`-valued nonnegative
functions. -/
theorem Lp_add_le_of_nonneg (hp : 1 ≤ p) (hf : ∀ i ∈ s, 0 ≤ f i) (hg : ∀ i ∈ s, 0 ≤ g i) :
(∑ i in s, (f i + g i) ^ p) ^ (1 / p) ≤
(∑ i in s, (f i) ^ p) ^ (1 / p) + (∑ i in s, (g i) ^ p) ^ (1 / p) :=
by convert Lp_add_le s f g hp using 2 ; [skip, congr' 1, congr' 1];
apply sum_congr rfl; intros i hi; simp only [abs_of_nonneg, hf i hi, hg i hi, add_nonneg]
end real
namespace ennreal
/-- Young's inequality, `ennreal` version with real conjugate exponents. -/
theorem young_inequality (a b : ennreal) {p q : ℝ} (hpq : p.is_conjugate_exponent q) :
a * b ≤ a ^ p / ennreal.of_real p + b ^ q / ennreal.of_real q :=
begin
by_cases h : a = ⊤ ∨ b = ⊤,
{ refine le_trans le_top (le_of_eq _),
repeat { rw div_eq_mul_inv },
cases h; rw h; simp [h, hpq.pos, hpq.symm.pos], },
push_neg at h, -- if a ≠ ⊤ and b ≠ ⊤, use the nnreal version: nnreal.young_inequality_real
rw [←coe_to_nnreal h.left, ←coe_to_nnreal h.right, ←coe_mul,
coe_rpow_of_nonneg _ hpq.nonneg, coe_rpow_of_nonneg _ hpq.symm.nonneg, ennreal.of_real,
ennreal.of_real, ←@coe_div (nnreal.of_real p) _ (by simp [hpq.pos]),
←@coe_div (nnreal.of_real q) _ (by simp [hpq.symm.pos]), ←coe_add, coe_le_coe],
exact nnreal.young_inequality_real a.to_nnreal b.to_nnreal hpq,
end
variables (f g : ι → ennreal) {p q : ℝ}
/-- Hölder inequality: the scalar product of two functions is bounded by the product of their
`L^p` and `L^q` norms when `p` and `q` are conjugate exponents. Version for sums over finite sets,
with `ennreal`-valued functions. -/
theorem inner_le_Lp_mul_Lq (hpq : p.is_conjugate_exponent q) :
(∑ i in s, f i * g i) ≤ (∑ i in s, (f i)^p) ^ (1/p) * (∑ i in s, (g i)^q) ^ (1/q) :=
begin
by_cases H : (∑ i in s, (f i)^p) ^ (1/p) = 0 ∨ (∑ i in s, (g i)^q) ^ (1/q) = 0,
{ replace H : (∀ i ∈ s, f i = 0) ∨ (∀ i ∈ s, g i = 0),
by simpa [ennreal.rpow_eq_zero_iff, hpq.pos, hpq.symm.pos, asymm hpq.pos, asymm hpq.symm.pos,
sum_eq_zero_iff_of_nonneg] using H,
have : ∀ i ∈ s, f i * g i = 0 := λ i hi, by cases H; simp [H i hi],
have : (∑ i in s, f i * g i) = (∑ i in s, 0) := sum_congr rfl this,
simp [this] },
push_neg at H,
by_cases H' : (∑ i in s, (f i)^p) ^ (1/p) = ⊤ ∨ (∑ i in s, (g i)^q) ^ (1/q) = ⊤,
{ cases H'; simp [H', -one_div, H] },
replace H' : (∀ i ∈ s, f i ≠ ⊤) ∧ (∀ i ∈ s, g i ≠ ⊤),
by simpa [ennreal.rpow_eq_top_iff, asymm hpq.pos, asymm hpq.symm.pos, hpq.pos, hpq.symm.pos,
ennreal.sum_eq_top_iff, not_or_distrib] using H',
have := ennreal.coe_le_coe.2 (@nnreal.inner_le_Lp_mul_Lq _ s (λ i, ennreal.to_nnreal (f i))
(λ i, ennreal.to_nnreal (g i)) _ _ hpq),
simp [← ennreal.coe_rpow_of_nonneg, le_of_lt (hpq.pos), le_of_lt (hpq.one_div_pos),
le_of_lt (hpq.symm.pos), le_of_lt (hpq.symm.one_div_pos)] at this,
convert this using 1;
[skip, congr' 2];
[skip, skip, simp, skip, simp];
{ apply finset.sum_congr rfl (λ i hi, _), simp [H'.1 i hi, H'.2 i hi, -with_zero.coe_mul,
with_top.coe_mul.symm] },
end
/-- Minkowski inequality: the `L_p` seminorm of the sum of two vectors is less than or equal
to the sum of the `L_p`-seminorms of the summands. A version for `ennreal` valued nonnegative
functions. -/
theorem Lp_add_le (hp : 1 ≤ p) :
(∑ i in s, (f i + g i) ^ p)^(1/p) ≤ (∑ i in s, (f i)^p) ^ (1/p) + (∑ i in s, (g i)^p) ^ (1/p) :=
begin
by_cases H' : (∑ i in s, (f i)^p) ^ (1/p) = ⊤ ∨ (∑ i in s, (g i)^p) ^ (1/p) = ⊤,
{ cases H'; simp [H', -one_div] },
have pos : 0 < p := lt_of_lt_of_le zero_lt_one hp,
replace H' : (∀ i ∈ s, f i ≠ ⊤) ∧ (∀ i ∈ s, g i ≠ ⊤),
by simpa [ennreal.rpow_eq_top_iff, asymm pos, pos, ennreal.sum_eq_top_iff,
not_or_distrib] using H',
have := ennreal.coe_le_coe.2 (@nnreal.Lp_add_le _ s (λ i, ennreal.to_nnreal (f i))
(λ i, ennreal.to_nnreal (g i)) _ hp),
push_cast [← ennreal.coe_rpow_of_nonneg, le_of_lt (pos), le_of_lt (one_div_pos.2 pos)] at this,
convert this using 2;
[skip, congr' 1, congr' 1];
{ apply finset.sum_congr rfl (λ i hi, _), simp [H'.1 i hi, H'.2 i hi] }
end
private lemma add_rpow_le_one_of_add_le_one {p : ℝ} (a b : ennreal) (hab : a + b ≤ 1)
(hp1 : 1 ≤ p) :
a ^ p + b ^ p ≤ 1 :=
begin
have h_le_one : ∀ x : ennreal, x ≤ 1 → x ^ p ≤ x, from λ x hx, rpow_le_self_of_le_one hx hp1,
have ha : a ≤ 1, from (self_le_add_right a b).trans hab,
have hb : b ≤ 1, from (self_le_add_left b a).trans hab,
exact (add_le_add (h_le_one a ha) (h_le_one b hb)).trans hab,
end
lemma add_rpow_le_rpow_add {p : ℝ} (a b : ennreal) (hp1 : 1 ≤ p) :
a ^ p + b ^ p ≤ (a + b) ^ p :=
begin
have hp_pos : 0 < p := lt_of_lt_of_le zero_lt_one hp1,
by_cases h_top : a + b = ⊤,
{ rw ←@ennreal.rpow_eq_top_iff_of_pos (a + b) p hp_pos at h_top,
rw h_top,
exact le_top, },
obtain ⟨ha_top, hb_top⟩ := add_ne_top.mp h_top,
by_cases h_zero : a + b = 0,
{ simp [add_eq_zero_iff.mp h_zero, ennreal.zero_rpow_of_pos hp_pos], },
have h_nonzero : ¬(a = 0 ∧ b = 0), by rwa add_eq_zero_iff at h_zero,
have h_add : a/(a+b) + b/(a+b) = 1, by rw [div_add_div_same, div_self h_zero h_top],
have h := add_rpow_le_one_of_add_le_one (a/(a+b)) (b/(a+b)) h_add.le hp1,
rw [div_rpow_of_nonneg a (a+b) hp_pos.le, div_rpow_of_nonneg b (a+b) hp_pos.le] at h,
have hab_0 : (a + b)^p ≠ 0, by simp [ha_top, hb_top, hp_pos, h_nonzero],
have hab_top : (a + b)^p ≠ ⊤, by simp [ha_top, hb_top, hp_pos, h_nonzero],
have h_mul : (a + b)^p * (a ^ p / (a + b) ^ p + b ^ p / (a + b) ^ p) ≤ (a + b)^p,
{ nth_rewrite 3 ←mul_one ((a + b)^p),
exact (mul_le_mul_left hab_0 hab_top).mpr h, },
rwa [div_eq_mul_inv, div_eq_mul_inv, mul_add, mul_comm (a^p), mul_comm (b^p), ←mul_assoc,
←mul_assoc, mul_inv_cancel hab_0 hab_top, one_mul, one_mul] at h_mul,
end
lemma rpow_add_rpow_le_add {p : ℝ} (a b : ennreal) (hp1 : 1 ≤ p) :
(a ^ p + b ^ p) ^ (1/p) ≤ a + b :=
begin
rw ←@ennreal.le_rpow_one_div_iff _ _ (1/p) (by simp [lt_of_lt_of_le zero_lt_one hp1]),
rw one_div_one_div,
exact add_rpow_le_rpow_add _ _ hp1,
end
theorem rpow_add_rpow_le {p q : ℝ} (a b : ennreal) (hp_pos : 0 < p) (hpq : p ≤ q) :
(a ^ q + b ^ q) ^ (1/q) ≤ (a ^ p + b ^ p) ^ (1/p) :=
begin
have h_rpow : ∀ a : ennreal, a^q = (a^p)^(q/p),
from λ a, by rw [←ennreal.rpow_mul, div_eq_inv_mul, ←mul_assoc,
_root_.mul_inv_cancel hp_pos.ne.symm, one_mul],
have h_rpow_add_rpow_le_add : ((a^p)^(q/p) + (b^p)^(q/p)) ^ (1/(q/p)) ≤ a^p + b^p,
{ refine rpow_add_rpow_le_add (a^p) (b^p) _,
rwa one_le_div hp_pos, },
rw [h_rpow a, h_rpow b, ennreal.le_rpow_one_div_iff hp_pos, ←ennreal.rpow_mul, mul_comm,
mul_one_div],
rwa one_div_div at h_rpow_add_rpow_le_add,
end
lemma rpow_add_le_add_rpow {p : ℝ} (a b : ennreal) (hp_pos : 0 < p) (hp1 : p ≤ 1) :
(a + b) ^ p ≤ a ^ p + b ^ p :=
begin
have h := rpow_add_rpow_le a b hp_pos hp1,
rw one_div_one at h,
repeat { rw ennreal.rpow_one at h },
exact (ennreal.le_rpow_one_div_iff hp_pos).mp h,
end
end ennreal
section lintegral
/-!
### Hölder's inequality for the Lebesgue integral of ennreal and nnreal functions
We prove `∫ (f * g) ∂μ ≤ (∫ f^p ∂μ) ^ (1/p) * (∫ g^q ∂μ) ^ (1/q)` for `p`, `q`
conjugate real exponents and `α→(e)nnreal` functions in several cases, the first two being useful
only to prove the more general results:
* `ennreal.lintegral_mul_le_one_of_lintegral_rpow_eq_one` : ennreal functions for which the
integrals on the right are equal to 1,
* `ennreal.lintegral_mul_le_Lp_mul_Lq_of_ne_zero_of_ne_top` : ennreal functions for which the
integrals on the right are neither ⊤ nor 0,
* `ennreal.lintegral_mul_le_Lp_mul_Lq` : ennreal functions,
* `nnreal.lintegral_mul_le_Lp_mul_Lq` : nnreal functions.
-/
open measure_theory
variables {α : Type*} [measurable_space α] {μ : measure α}
namespace ennreal
lemma lintegral_mul_le_one_of_lintegral_rpow_eq_one {p q : ℝ} (hpq : p.is_conjugate_exponent q)
{f g : α → ennreal} (hf : ae_measurable f μ) (hg : ae_measurable g μ)
(hf_norm : ∫⁻ a, (f a)^p ∂μ = 1) (hg_norm : ∫⁻ a, (g a)^q ∂μ = 1) :
∫⁻ a, (f * g) a ∂μ ≤ 1 :=
begin
calc ∫⁻ (a : α), ((f * g) a) ∂μ
≤ ∫⁻ (a : α), ((f a)^p / ennreal.of_real p + (g a)^q / ennreal.of_real q) ∂μ :
lintegral_mono (λ a, young_inequality (f a) (g a) hpq)
... = 1 :
begin
simp only [div_eq_mul_inv],
rw lintegral_add',
{ rw [lintegral_mul_const'' _ hf.ennreal_rpow_const,
lintegral_mul_const'' _ hg.ennreal_rpow_const, hf_norm, hg_norm, ← div_eq_mul_inv,
← div_eq_mul_inv, hpq.inv_add_inv_conj_ennreal], },
{ exact hf.ennreal_rpow_const.ennreal_mul ae_measurable_const, },
{ exact hg.ennreal_rpow_const.ennreal_mul ae_measurable_const, },
end
end
/-- Function multiplied by the inverse of its p-seminorm `(∫⁻ f^p ∂μ) ^ 1/p`-/
def fun_mul_inv_snorm (f : α → ennreal) (p : ℝ) (μ : measure α) : α → ennreal :=
λ a, (f a) * ((∫⁻ c, (f c) ^ p ∂μ) ^ (1 / p))⁻¹
lemma fun_eq_fun_mul_inv_snorm_mul_snorm {p : ℝ} (f : α → ennreal)
(hf_nonzero : ∫⁻ a, (f a) ^ p ∂μ ≠ 0) (hf_top : ∫⁻ a, (f a) ^ p ∂μ ≠ ⊤) {a : α} :
f a = (fun_mul_inv_snorm f p μ a) * (∫⁻ c, (f c)^p ∂μ)^(1/p) :=
by simp [fun_mul_inv_snorm, mul_assoc, inv_mul_cancel, hf_nonzero, hf_top]
lemma fun_mul_inv_snorm_rpow {p : ℝ} (hp0 : 0 < p) {f : α → ennreal} {a : α} :
(fun_mul_inv_snorm f p μ a) ^ p = (f a)^p * (∫⁻ c, (f c) ^ p ∂μ)⁻¹ :=
begin
rw [fun_mul_inv_snorm, mul_rpow_of_nonneg _ _ (le_of_lt hp0)],
suffices h_inv_rpow : ((∫⁻ (c : α), f c ^ p ∂μ) ^ (1 / p))⁻¹ ^ p = (∫⁻ (c : α), f c ^ p ∂μ)⁻¹,
by rw h_inv_rpow,
rw [inv_rpow_of_pos hp0, ←rpow_mul, div_eq_mul_inv, one_mul,
_root_.inv_mul_cancel (ne_of_lt hp0).symm, rpow_one],
end
lemma lintegral_rpow_fun_mul_inv_snorm_eq_one {p : ℝ} (hp0_lt : 0 < p) {f : α → ennreal}
(hf : ae_measurable f μ) (hf_nonzero : ∫⁻ a, (f a)^p ∂μ ≠ 0) (hf_top : ∫⁻ a, (f a)^p ∂μ ≠ ⊤) :
∫⁻ c, (fun_mul_inv_snorm f p μ c)^p ∂μ = 1 :=
begin
simp_rw fun_mul_inv_snorm_rpow hp0_lt,
rw [lintegral_mul_const'' _ hf.ennreal_rpow_const, mul_inv_cancel hf_nonzero hf_top],
end
/-- Hölder's inequality in case of finite non-zero integrals -/
lemma lintegral_mul_le_Lp_mul_Lq_of_ne_zero_of_ne_top {p q : ℝ} (hpq : p.is_conjugate_exponent q)
{f g : α → ennreal} (hf : ae_measurable f μ) (hg : ae_measurable g μ)
(hf_nontop : ∫⁻ a, (f a)^p ∂μ ≠ ⊤) (hg_nontop : ∫⁻ a, (g a)^q ∂μ ≠ ⊤)
(hf_nonzero : ∫⁻ a, (f a)^p ∂μ ≠ 0) (hg_nonzero : ∫⁻ a, (g a)^q ∂μ ≠ 0) :
∫⁻ a, (f * g) a ∂μ ≤ (∫⁻ a, (f a)^p ∂μ)^(1/p) * (∫⁻ a, (g a)^q ∂μ)^(1/q) :=
begin
let npf := (∫⁻ (c : α), (f c) ^ p ∂μ) ^ (1/p),
let nqg := (∫⁻ (c : α), (g c) ^ q ∂μ) ^ (1/q),
calc ∫⁻ (a : α), (f * g) a ∂μ
= ∫⁻ (a : α), ((fun_mul_inv_snorm f p μ * fun_mul_inv_snorm g q μ) a)
* (npf * nqg) ∂μ :
begin
refine lintegral_congr (λ a, _),
rw [pi.mul_apply, fun_eq_fun_mul_inv_snorm_mul_snorm f hf_nonzero hf_nontop,
fun_eq_fun_mul_inv_snorm_mul_snorm g hg_nonzero hg_nontop, pi.mul_apply],
ring,
end
... ≤ npf * nqg :
begin
rw lintegral_mul_const' (npf * nqg) _ (by simp [hf_nontop, hg_nontop, hf_nonzero, hg_nonzero]),
nth_rewrite 1 ←one_mul (npf * nqg),
refine mul_le_mul _ (le_refl (npf * nqg)),
have hf1 := lintegral_rpow_fun_mul_inv_snorm_eq_one hpq.pos hf hf_nonzero hf_nontop,
have hg1 := lintegral_rpow_fun_mul_inv_snorm_eq_one hpq.symm.pos hg hg_nonzero hg_nontop,
exact lintegral_mul_le_one_of_lintegral_rpow_eq_one hpq (hf.ennreal_mul ae_measurable_const)
(hg.ennreal_mul ae_measurable_const) hf1 hg1,
end
end
lemma ae_eq_zero_of_lintegral_rpow_eq_zero {p : ℝ} (hp0_lt : 0 < p) {f : α → ennreal}
(hf : ae_measurable f μ) (hf_zero : ∫⁻ a, (f a)^p ∂μ = 0) :
f =ᵐ[μ] 0 :=
begin
rw lintegral_eq_zero_iff' hf.ennreal_rpow_const at hf_zero,
refine filter.eventually.mp hf_zero (filter.eventually_of_forall (λ x, _)),
dsimp only,
rw [pi.zero_apply, rpow_eq_zero_iff],
intro hx,
cases hx,
{ exact hx.left, },
{ exfalso,
linarith, },
end
lemma lintegral_mul_eq_zero_of_lintegral_rpow_eq_zero {p : ℝ} (hp0_lt : 0 < p)
{f g : α → ennreal} (hf : ae_measurable f μ) (hf_zero : ∫⁻ a, (f a)^p ∂μ = 0) :
∫⁻ a, (f * g) a ∂μ = 0 :=
begin
rw ←@lintegral_zero_fun α _ μ,
refine lintegral_congr_ae _,
suffices h_mul_zero : f * g =ᵐ[μ] 0 * g , by rwa zero_mul at h_mul_zero,
have hf_eq_zero : f =ᵐ[μ] 0, from ae_eq_zero_of_lintegral_rpow_eq_zero hp0_lt hf hf_zero,
exact filter.eventually_eq.mul hf_eq_zero (ae_eq_refl g),
end
lemma lintegral_mul_le_Lp_mul_Lq_of_ne_zero_of_eq_top {p q : ℝ} (hp0_lt : 0 < p) (hq0 : 0 ≤ q)
{f g : α → ennreal} (hf_top : ∫⁻ a, (f a)^p ∂μ = ⊤) (hg_nonzero : ∫⁻ a, (g a)^q ∂μ ≠ 0) :
∫⁻ a, (f * g) a ∂μ ≤ (∫⁻ a, (f a)^p ∂μ) ^ (1/p) * (∫⁻ a, (g a)^q ∂μ) ^ (1/q) :=
begin
refine le_trans le_top (le_of_eq _),
have hp0_inv_lt : 0 < 1/p, by simp [hp0_lt],
rw [hf_top, ennreal.top_rpow_of_pos hp0_inv_lt],
simp [hq0, hg_nonzero],
end
/-- Hölder's inequality for functions `α → ennreal`. The integral of the product of two functions
is bounded by the product of their `ℒp` and `ℒq` seminorms when `p` and `q` are conjugate
exponents. -/
theorem lintegral_mul_le_Lp_mul_Lq (μ : measure α) {p q : ℝ} (hpq : p.is_conjugate_exponent q)
{f g : α → ennreal} (hf : ae_measurable f μ) (hg : ae_measurable g μ) :
∫⁻ a, (f * g) a ∂μ ≤ (∫⁻ a, (f a)^p ∂μ) ^ (1/p) * (∫⁻ a, (g a)^q ∂μ) ^ (1/q) :=
begin
by_cases hf_zero : ∫⁻ a, (f a) ^ p ∂μ = 0,
{ refine le_trans (le_of_eq _) (zero_le _),
exact lintegral_mul_eq_zero_of_lintegral_rpow_eq_zero hpq.pos hf hf_zero, },
by_cases hg_zero : ∫⁻ a, (g a) ^ q ∂μ = 0,
{ refine le_trans (le_of_eq _) (zero_le _),
rw mul_comm,
exact lintegral_mul_eq_zero_of_lintegral_rpow_eq_zero hpq.symm.pos hg hg_zero, },
by_cases hf_top : ∫⁻ a, (f a) ^ p ∂μ = ⊤,
{ exact lintegral_mul_le_Lp_mul_Lq_of_ne_zero_of_eq_top hpq.pos hpq.symm.nonneg hf_top hg_zero, },
by_cases hg_top : ∫⁻ a, (g a) ^ q ∂μ = ⊤,
{ rw [mul_comm, mul_comm ((∫⁻ (a : α), (f a) ^ p ∂μ) ^ (1 / p))],
exact lintegral_mul_le_Lp_mul_Lq_of_ne_zero_of_eq_top hpq.symm.pos hpq.nonneg hg_top hf_zero, },
-- non-⊤ non-zero case
exact ennreal.lintegral_mul_le_Lp_mul_Lq_of_ne_zero_of_ne_top hpq hf hg hf_top hg_top hf_zero
hg_zero,
end
lemma lintegral_rpow_add_lt_top_of_lintegral_rpow_lt_top {p : ℝ}
{f g : α → ennreal} (hf : ae_measurable f μ) (hf_top : ∫⁻ a, (f a) ^ p ∂μ < ⊤)
(hg : ae_measurable g μ) (hg_top : ∫⁻ a, (g a) ^ p ∂μ < ⊤) (hp1 : 1 ≤ p) :
∫⁻ a, ((f + g) a) ^ p ∂μ < ⊤ :=
begin
have hp0_lt : 0 < p, from lt_of_lt_of_le zero_lt_one hp1,
have hp0 : 0 ≤ p, from le_of_lt hp0_lt,
calc ∫⁻ (a : α), (f a + g a) ^ p ∂μ
≤ ∫⁻ a, ((2:ennreal)^(p-1) * (f a) ^ p + (2:ennreal)^(p-1) * (g a) ^ p) ∂ μ :
begin
refine lintegral_mono (λ a, _),
dsimp only,
have h_zero_lt_half_rpow : (0 : ennreal) < (1 / 2) ^ p,
{ rw [←ennreal.zero_rpow_of_pos hp0_lt],
exact ennreal.rpow_lt_rpow (by simp [zero_lt_one]) hp0_lt, },
have h_rw : (1 / 2) ^ p * (2:ennreal) ^ (p - 1) = 1 / 2,
{ rw [sub_eq_add_neg, ennreal.rpow_add _ _ ennreal.two_ne_zero ennreal.coe_ne_top,
←mul_assoc, ←ennreal.mul_rpow_of_nonneg _ _ hp0, one_div,
ennreal.inv_mul_cancel ennreal.two_ne_zero ennreal.coe_ne_top, ennreal.one_rpow,
one_mul, ennreal.rpow_neg_one], },
rw ←ennreal.mul_le_mul_left (ne_of_lt h_zero_lt_half_rpow).symm _,
{ rw [mul_add, ← mul_assoc, ← mul_assoc, h_rw, ←ennreal.mul_rpow_of_nonneg _ _ hp0, mul_add],
refine ennreal.rpow_arith_mean_le_arith_mean2_rpow (1/2 : ennreal) (1/2 : ennreal)
(f a) (g a) _ hp1,
rw [ennreal.div_add_div_same, one_add_one_eq_two,
ennreal.div_self ennreal.two_ne_zero ennreal.coe_ne_top], },
{ rw ←ennreal.lt_top_iff_ne_top,
refine ennreal.rpow_lt_top_of_nonneg hp0 _,
rw [one_div, ennreal.inv_ne_top],
exact ennreal.two_ne_zero, },
end
... < ⊤ :
begin
rw [lintegral_add', lintegral_const_mul'' _ hf.ennreal_rpow_const,
lintegral_const_mul'' _ hg.ennreal_rpow_const, ennreal.add_lt_top],
{ have h_two : (2 : ennreal) ^ (p - 1) < ⊤,
from ennreal.rpow_lt_top_of_nonneg (by simp [hp1]) ennreal.coe_ne_top,
repeat {rw ennreal.mul_lt_top_iff},
simp [hf_top, hg_top, h_two], },
{ exact (ennreal.continuous_const_mul (by simp)).measurable.comp_ae_measurable
hf.ennreal_rpow_const, },
{ exact (ennreal.continuous_const_mul (by simp)).measurable.comp_ae_measurable
hg.ennreal_rpow_const },
end
end
lemma lintegral_Lp_mul_le_Lq_mul_Lr {α} [measurable_space α] {p q r : ℝ} (hp0_lt : 0 < p)
(hpq : p < q) (hpqr : 1/p = 1/q + 1/r) (μ : measure α) {f g : α → ennreal}
(hf : ae_measurable f μ) (hg : ae_measurable g μ) :
(∫⁻ a, ((f * g) a)^p ∂μ) ^ (1/p) ≤ (∫⁻ a, (f a)^q ∂μ) ^ (1/q) * (∫⁻ a, (g a)^r ∂μ) ^ (1/r) :=
begin
have hp0_ne : p ≠ 0, from (ne_of_lt hp0_lt).symm,
have hp0 : 0 ≤ p, from le_of_lt hp0_lt,
have hq0_lt : 0 < q, from lt_of_le_of_lt hp0 hpq,
have hq0_ne : q ≠ 0, from (ne_of_lt hq0_lt).symm,
have h_one_div_r : 1/r = 1/p - 1/q, by simp [hpqr],
have hr0_ne : r ≠ 0,
{ have hr_inv_pos : 0 < 1/r,
by rwa [h_one_div_r, sub_pos, one_div_lt_one_div hq0_lt hp0_lt],
rw [one_div, _root_.inv_pos] at hr_inv_pos,
exact (ne_of_lt hr_inv_pos).symm, },
let p2 := q/p,
let q2 := p2.conjugate_exponent,
have hp2q2 : p2.is_conjugate_exponent q2,
from real.is_conjugate_exponent_conjugate_exponent (by simp [lt_div_iff, hpq, hp0_lt]),
calc (∫⁻ (a : α), ((f * g) a) ^ p ∂μ) ^ (1 / p)
= (∫⁻ (a : α), (f a)^p * (g a)^p ∂μ) ^ (1 / p) :
by simp_rw [pi.mul_apply, ennreal.mul_rpow_of_nonneg _ _ hp0]
... ≤ ((∫⁻ a, (f a)^(p * p2) ∂ μ)^(1/p2) * (∫⁻ a, (g a)^(p * q2) ∂ μ)^(1/q2)) ^ (1/p) :
begin
refine ennreal.rpow_le_rpow _ (by simp [hp0]),
simp_rw ennreal.rpow_mul,
exact ennreal.lintegral_mul_le_Lp_mul_Lq μ hp2q2 hf.ennreal_rpow_const hg.ennreal_rpow_const,
end
... = (∫⁻ (a : α), (f a) ^ q ∂μ) ^ (1 / q) * (∫⁻ (a : α), (g a) ^ r ∂μ) ^ (1 / r) :
begin
rw [@ennreal.mul_rpow_of_nonneg _ _ (1/p) (by simp [hp0]), ←ennreal.rpow_mul,
←ennreal.rpow_mul],
have hpp2 : p * p2 = q,
{ symmetry, rw [mul_comm, ←div_eq_iff hp0_ne], },
have hpq2 : p * q2 = r,
{ rw [← inv_inv' r, ← one_div, ← one_div, h_one_div_r],
field_simp [q2, real.conjugate_exponent, p2, hp0_ne, hq0_ne] },
simp_rw [div_mul_div, mul_one, mul_comm p2, mul_comm q2, hpp2, hpq2],
end
end
lemma lintegral_mul_rpow_le_lintegral_rpow_mul_lintegral_rpow {p q : ℝ}
(hpq : p.is_conjugate_exponent q) {f g : α → ennreal}
(hf : ae_measurable f μ) (hg : ae_measurable g μ) (hf_top : ∫⁻ a, (f a) ^ p ∂μ ≠ ⊤) :
∫⁻ a, (f a) * (g a) ^ (p - 1) ∂μ ≤ (∫⁻ a, (f a)^p ∂μ) ^ (1/p) * (∫⁻ a, (g a)^p ∂μ) ^ (1/q) :=
begin
refine le_trans (ennreal.lintegral_mul_le_Lp_mul_Lq μ hpq hf hg.ennreal_rpow_const) _,
by_cases hf_zero_rpow : (∫⁻ (a : α), (f a) ^ p ∂μ) ^ (1 / p) = 0,
{ rw [hf_zero_rpow, zero_mul],
exact zero_le _, },
have hf_top_rpow : (∫⁻ (a : α), (f a) ^ p ∂μ) ^ (1 / p) ≠ ⊤,
{ by_contra h,
push_neg at h,
refine hf_top _,
have hp_not_neg : ¬ p < 0, by simp [hpq.nonneg],
simpa [hpq.pos, hp_not_neg] using h, },
refine (ennreal.mul_le_mul_left hf_zero_rpow hf_top_rpow).mpr (le_of_eq _),
congr,
ext1 a,
rw [←ennreal.rpow_mul, hpq.sub_one_mul_conj],
end
lemma lintegral_rpow_add_le_add_snorm_mul_lintegral_rpow_add {p q : ℝ}
(hpq : p.is_conjugate_exponent q) {f g : α → ennreal} (hf : ae_measurable f μ)
(hf_top : ∫⁻ a, (f a) ^ p ∂μ ≠ ⊤) (hg : ae_measurable g μ) (hg_top : ∫⁻ a, (g a) ^ p ∂μ ≠ ⊤) :
∫⁻ a, ((f + g) a)^p ∂ μ
≤ ((∫⁻ a, (f a)^p ∂μ) ^ (1/p) + (∫⁻ a, (g a)^p ∂μ) ^ (1/p))
* (∫⁻ a, (f a + g a)^p ∂μ) ^ (1/q) :=
begin
calc ∫⁻ a, ((f+g) a) ^ p ∂μ ≤ ∫⁻ a, ((f + g) a) * ((f + g) a) ^ (p - 1) ∂μ :
begin
refine lintegral_mono (λ a, _),
dsimp only,
by_cases h_zero : (f + g) a = 0,
{ rw [h_zero, ennreal.zero_rpow_of_pos hpq.pos],
exact zero_le _, },
by_cases h_top : (f + g) a = ⊤,
{ rw [h_top, ennreal.top_rpow_of_pos hpq.sub_one_pos, ennreal.top_mul_top],
exact le_top, },
refine le_of_eq _,
nth_rewrite 1 ←ennreal.rpow_one ((f + g) a),
rw [←ennreal.rpow_add _ _ h_zero h_top, add_sub_cancel'_right],
end
... = ∫⁻ (a : α), f a * (f + g) a ^ (p - 1) ∂μ + ∫⁻ (a : α), g a * (f + g) a ^ (p - 1) ∂μ :
begin
have h_add_m : ae_measurable (λ (a : α), ((f + g) a) ^ (p-1)) μ,
from (hf.add hg).ennreal_rpow_const,
have h_add_apply : ∫⁻ (a : α), (f + g) a * (f + g) a ^ (p - 1) ∂μ
= ∫⁻ (a : α), (f a + g a) * (f + g) a ^ (p - 1) ∂μ,
from rfl,
simp_rw [h_add_apply, add_mul],
rw lintegral_add' (hf.ennreal_mul h_add_m) (hg.ennreal_mul h_add_m),
end
... ≤ ((∫⁻ a, (f a)^p ∂μ) ^ (1/p) + (∫⁻ a, (g a)^p ∂μ) ^ (1/p))
* (∫⁻ a, (f a + g a)^p ∂μ) ^ (1/q) :
begin
rw add_mul,
exact add_le_add
(lintegral_mul_rpow_le_lintegral_rpow_mul_lintegral_rpow hpq hf (hf.add hg) hf_top)
(lintegral_mul_rpow_le_lintegral_rpow_mul_lintegral_rpow hpq hg (hf.add hg) hg_top),
end
end
private lemma lintegral_Lp_add_le_aux {p q : ℝ}
(hpq : p.is_conjugate_exponent q) {f g : α → ennreal} (hf : ae_measurable f μ)
(hf_top : ∫⁻ a, (f a) ^ p ∂μ ≠ ⊤) (hg : ae_measurable g μ) (hg_top : ∫⁻ a, (g a) ^ p ∂μ ≠ ⊤)
(h_add_zero : ∫⁻ a, ((f+g) a) ^ p ∂ μ ≠ 0) (h_add_top : ∫⁻ a, ((f+g) a) ^ p ∂ μ ≠ ⊤) :
(∫⁻ a, ((f + g) a)^p ∂ μ) ^ (1/p) ≤ (∫⁻ a, (f a)^p ∂μ) ^ (1/p) + (∫⁻ a, (g a)^p ∂μ) ^ (1/p) :=
begin
have hp_not_nonpos : ¬ p ≤ 0, by simp [hpq.pos],
have htop_rpow : (∫⁻ a, ((f+g) a) ^ p ∂μ)^(1/p) ≠ ⊤,
{ by_contra h,
push_neg at h,
exact h_add_top (@ennreal.rpow_eq_top_of_nonneg _ (1/p) (by simp [hpq.nonneg]) h), },
have h0_rpow : (∫⁻ a, ((f+g) a) ^ p ∂ μ) ^ (1/p) ≠ 0,
by simp [h_add_zero, h_add_top, hpq.nonneg, hp_not_nonpos, -pi.add_apply],
suffices h : 1 ≤ (∫⁻ (a : α), ((f+g) a)^p ∂μ) ^ -(1/p)
* ((∫⁻ (a : α), (f a)^p ∂μ) ^ (1/p) + (∫⁻ (a : α), (g a)^p ∂μ) ^ (1/p)),
by rwa [←mul_le_mul_left h0_rpow htop_rpow, ←mul_assoc, ←rpow_add _ _ h_add_zero h_add_top,
←sub_eq_add_neg, _root_.sub_self, rpow_zero, one_mul, mul_one] at h,
have h : ∫⁻ (a : α), ((f+g) a)^p ∂μ
≤ ((∫⁻ (a : α), (f a)^p ∂μ) ^ (1/p) + (∫⁻ (a : α), (g a)^p ∂μ) ^ (1/p))
* (∫⁻ (a : α), ((f+g) a)^p ∂μ) ^ (1/q),
from lintegral_rpow_add_le_add_snorm_mul_lintegral_rpow_add hpq hf hf_top hg hg_top,
have h_one_div_q : 1/q = 1 - 1/p, by { nth_rewrite 1 ←hpq.inv_add_inv_conj, ring, },
simp_rw [h_one_div_q, sub_eq_add_neg 1 (1/p), ennreal.rpow_add _ _ h_add_zero h_add_top,
rpow_one] at h,
nth_rewrite 1 mul_comm at h,
nth_rewrite 0 ←one_mul (∫⁻ (a : α), ((f+g) a) ^ p ∂μ) at h,
rwa [←mul_assoc, ennreal.mul_le_mul_right h_add_zero h_add_top, mul_comm] at h,
end
/-- Minkowski's inequality for functions `α → ennreal`: the `ℒp` seminorm of the sum of two
functions is bounded by the sum of their `ℒp` seminorms. -/
theorem lintegral_Lp_add_le {p : ℝ} {f g : α → ennreal}
(hf : ae_measurable f μ) (hg : ae_measurable g μ) (hp1 : 1 ≤ p) :
(∫⁻ a, ((f + g) a)^p ∂ μ) ^ (1/p) ≤ (∫⁻ a, (f a)^p ∂μ) ^ (1/p) + (∫⁻ a, (g a)^p ∂μ) ^ (1/p) :=
begin
have hp_pos : 0 < p, from lt_of_lt_of_le zero_lt_one hp1,
by_cases hf_top : ∫⁻ a, (f a) ^ p ∂μ = ⊤,
{ simp [hf_top, hp_pos], },
by_cases hg_top : ∫⁻ a, (g a) ^ p ∂μ = ⊤,
{ simp [hg_top, hp_pos], },
by_cases h1 : p = 1,
{ refine le_of_eq _,
simp_rw [h1, one_div_one, ennreal.rpow_one],
exact lintegral_add' hf hg, },
have hp1_lt : 1 < p, by { refine lt_of_le_of_ne hp1 _, symmetry, exact h1, },
have hpq := real.is_conjugate_exponent_conjugate_exponent hp1_lt,
by_cases h0 : ∫⁻ a, ((f+g) a) ^ p ∂ μ = 0,
{ rw [h0, @ennreal.zero_rpow_of_pos (1/p) (by simp [lt_of_lt_of_le zero_lt_one hp1])],
exact zero_le _, },
have htop : ∫⁻ a, ((f+g) a) ^ p ∂ μ ≠ ⊤,
{ rw ←ne.def at hf_top hg_top,
rw ←ennreal.lt_top_iff_ne_top at hf_top hg_top ⊢,
exact lintegral_rpow_add_lt_top_of_lintegral_rpow_lt_top hf hf_top hg hg_top hp1, },
exact lintegral_Lp_add_le_aux hpq hf hf_top hg hg_top h0 htop,
end
end ennreal
/-- Hölder's inequality for functions `α → ℝ≥0`. The integral of the product of two functions
is bounded by the product of their `ℒp` and `ℒq` seminorms when `p` and `q` are conjugate
exponents. -/
theorem nnreal.lintegral_mul_le_Lp_mul_Lq {p q : ℝ} (hpq : p.is_conjugate_exponent q)
{f g : α → ℝ≥0} (hf : ae_measurable f μ) (hg : ae_measurable g μ) :
∫⁻ a, (f * g) a ∂μ ≤ (∫⁻ a, (f a)^p ∂μ)^(1/p) * (∫⁻ a, (g a)^q ∂μ)^(1/q) :=
begin
simp_rw [pi.mul_apply, ennreal.coe_mul],
exact ennreal.lintegral_mul_le_Lp_mul_Lq μ hpq hf.ennreal_coe hg.ennreal_coe,
end
end lintegral
|
1851b6b5ec483d9e9a19ee6b4239283a5587f63b | a9d0fb7b0e4f802bd3857b803e6c5c23d87fef91 | /hott/eq2.hlean | 493ab7d79777c946f2f0b3ce1674d0276ee828fe | [
"Apache-2.0"
] | permissive | soonhokong/lean-osx | 4a954262c780e404c1369d6c06516161d07fcb40 | 3670278342d2f4faa49d95b46d86642d7875b47c | refs/heads/master | 1,611,410,334,552 | 1,474,425,686,000 | 1,474,425,686,000 | 12,043,103 | 5 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 4,648 | 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 2-dimensional paths
-/
import .cubical.square
open function
namespace eq
variables {A B C : Type} {f : A → B} {a a' a₁ a₂ a₃ a₄ : A} {b b' : B}
theorem ap_is_constant_eq (p : Πx, f x = b) (q : a = a') :
ap_is_constant p q =
eq_con_inv_of_con_eq ((eq_of_square (square_of_pathover (apdo p q)))⁻¹ ⬝
whisker_left (p a) (ap_constant q b)) :=
begin
induction q, esimp, generalize (p a), intro p, cases p, apply idpath idp
end
definition ap_inv2 {p q : a = a'} (r : p = q)
: square (ap (ap f) (inverse2 r))
(inverse2 (ap (ap f) r))
(ap_inv f p)
(ap_inv f q) :=
by induction r;exact hrfl
definition ap_con2 {p₁ q₁ : a₁ = a₂} {p₂ q₂ : a₂ = a₃} (r₁ : p₁ = q₁) (r₂ : p₂ = q₂)
: square (ap (ap f) (r₁ ◾ r₂))
(ap (ap f) r₁ ◾ ap (ap f) r₂)
(ap_con f p₁ p₂)
(ap_con f q₁ q₂) :=
by induction r₂;induction r₁;exact hrfl
theorem ap_con_right_inv_sq {A B : Type} {a1 a2 : A} (f : A → B) (p : a1 = a2) :
square (ap (ap f) (con.right_inv p))
(con.right_inv (ap f p))
(ap_con f p p⁻¹ ⬝ whisker_left _ (ap_inv f p))
idp :=
by cases p;apply hrefl
theorem ap_con_left_inv_sq {A B : Type} {a1 a2 : A} (f : A → B) (p : a1 = a2) :
square (ap (ap f) (con.left_inv p))
(con.left_inv (ap f p))
(ap_con f p⁻¹ p ⬝ whisker_right (ap_inv f p) _)
idp :=
by cases p;apply vrefl
theorem ap_ap_is_constant {A B C : Type} (g : B → C) {f : A → B} {b : B}
(p : Πx, f x = b) {x y : A} (q : x = y) :
square (ap (ap g) (ap_is_constant p q))
(ap_is_constant (λa, ap g (p a)) q)
(ap_compose g f q)⁻¹
(!ap_con ⬝ whisker_left _ !ap_inv) :=
begin
induction q, esimp, generalize (p x), intro p, cases p, apply ids
-- induction q, rewrite [↑ap_compose,ap_inv], apply hinverse, apply ap_con_right_inv_sq,
end
theorem ap_ap_compose {A B C D : Type} (h : C → D) (g : B → C) (f : A → B)
{x y : A} (p : x = y) :
square (ap_compose (h ∘ g) f p)
(ap (ap h) (ap_compose g f p))
(ap_compose h (g ∘ f) p)
(ap_compose h g (ap f p)) :=
by induction p;exact ids
theorem ap_compose_inv {A B C : Type} (g : B → C) (f : A → B)
{x y : A} (p : x = y) :
square (ap_compose g f p⁻¹)
(inverse2 (ap_compose g f p) ⬝ (ap_inv g (ap f p))⁻¹)
(ap_inv (g ∘ f) p)
(ap (ap g) (ap_inv f p)) :=
by induction p;exact ids
theorem ap_compose_con (g : B → C) (f : A → B) (p : a₁ = a₂) (q : a₂ = a₃) :
square (ap_compose g f (p ⬝ q))
(ap_compose g f p ◾ ap_compose g f q ⬝ (ap_con g (ap f p) (ap f q))⁻¹)
(ap_con (g ∘ f) p q)
(ap (ap g) (ap_con f p q)) :=
by induction q;induction p;exact ids
theorem ap_compose_natural {A B C : Type} (g : B → C) (f : A → B)
{x y : A} {p q : x = y} (r : p = q) :
square (ap (ap (g ∘ f)) r)
(ap (ap g ∘ ap f) r)
(ap_compose g f p)
(ap_compose g f q) :=
natural_square (ap_compose g f) r
theorem whisker_right_eq_of_con_inv_eq_idp {p q : a₁ = a₂} (r : p ⬝ q⁻¹ = idp) :
whisker_right (eq_of_con_inv_eq_idp r) q⁻¹ ⬝ con.right_inv q = r :=
by induction q; esimp at r; cases r; reflexivity
theorem ap_eq_of_con_inv_eq_idp (f : A → B) {p q : a₁ = a₂} (r : p ⬝ q⁻¹ = idp)
: ap02 f (eq_of_con_inv_eq_idp r) =
eq_of_con_inv_eq_idp (whisker_left _ !ap_inv⁻¹ ⬝ !ap_con⁻¹ ⬝ ap02 f r)
:=
by induction q;esimp at *;cases r;reflexivity
theorem eq_of_con_inv_eq_idp_con2 {p p' q q' : a₁ = a₂} (r : p = p') (s : q = q')
(t : p' ⬝ q'⁻¹ = idp)
: eq_of_con_inv_eq_idp (r ◾ inverse2 s ⬝ t) = r ⬝ eq_of_con_inv_eq_idp t ⬝ s⁻¹ :=
by induction s;induction r;induction q;reflexivity
definition naturality_apdo_eq {A : Type} {B : A → Type} {a a₂ : A} {f g : Πa, B a}
(H : f ~ g) (p : a = a₂)
: apdo f p = concato_eq (eq_concato (H a) (apdo g p)) (H a₂)⁻¹ :=
begin
induction p, esimp,
generalizes [H a, g a], intro ga Ha, induction Ha,
reflexivity
end
theorem con_tr_idp {P : A → Type} {x y : A} (q : x = y) (u : P x) :
con_tr idp q u = ap (λp, p ▸ u) (idp_con q) :=
by induction q;reflexivity
end eq
|
d7fe8322aa1b28d83987007442c7ddd2f66d39f5 | 367134ba5a65885e863bdc4507601606690974c1 | /src/algebra/category/Group/abelian.lean | a8c5b20877bbe0c68d7d9f2d12c9ffaac7a85c2f | [
"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 | 1,400 | 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.category.Group.Z_Module_equivalence
import algebra.category.Group.limits
import algebra.category.Group.colimits
import algebra.category.Module.abelian
import category_theory.abelian.basic
/-!
# The category of abelian groups is abelian
-/
open category_theory
open category_theory.limits
universe u
noncomputable theory
namespace AddCommGroup
section
variables {X Y : AddCommGroup.{u}} (f : X ⟶ Y)
/-- In the category of abelian groups, every monomorphism is normal. -/
def normal_mono (hf : mono f) : normal_mono f :=
equivalence_reflects_normal_mono (forget₂ (Module.{u} ℤ) AddCommGroup.{u}).inv $
Module.normal_mono _ $ right_adjoint_preserves_mono (functor.adjunction _) hf
/-- In the category of abelian groups, every epimorphism is normal. -/
def normal_epi (hf : epi f) : normal_epi f :=
equivalence_reflects_normal_epi (forget₂ (Module.{u} ℤ) AddCommGroup.{u}).inv $
Module.normal_epi _ $ left_adjoint_preserves_epi (functor.adjunction _) hf
end
/-- The category of abelian groups is abelian. -/
instance : abelian AddCommGroup :=
{ has_finite_products := by { dsimp [has_finite_products], apply_instance },
normal_mono := λ X Y, normal_mono,
normal_epi := λ X Y, normal_epi }
end AddCommGroup
|
a9deb3e9b8c4182a38fff4e523f55360c4f2b7bb | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/simp_lemma_issue.lean | d39fc1f81608dfaea0c8c476141ba69fb7345837 | [
"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 | 690 | lean | universe variables u
class comm_semiring (α : Type*) extends has_zero α, has_add α, has_one α, has_mul α.
lemma zero_add {α : Type*} [comm_semiring α] (a : α) : (0:α) + a = a := sorry
lemma add_zero {α : Type*} [comm_semiring α] (a : α) : a + 0 = a := sorry
instance foo : comm_semiring nat :=
{ zero := 0, one := 1, add := (+), mul := (*) }
def ex {α : Type u} [comm_semiring α] (a : α) : 0 + a = a :=
zero_add a
-- local attribute [-simp] zero_add add_zero
attribute [simp] ex
example (a b : nat) : 0 + 0 + a = a :=
by simp
-- local attribute [-ematch] zero_add add_zero
attribute [ematch] ex
example (a b : nat) : 0 + 0 + a = a :=
by using_smt $ smt_tactic.eblast
|
a5c8bcd36ffb2cddaf9e9b5f24f3561bd71eb77a | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/Lean3Lib/init/meta/async_tactic_auto.lean | 1abb48a7fc2cd90159a72a7de0e1fad6cb0816b7 | [] | 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 | 312 | lean | /-
Copyright (c) 2017 Gabriel Ebner. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Gabriel Ebner
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.meta.tactic
import Mathlib.Lean3Lib.init.meta.interactive
namespace Mathlib
namespace tactic
end Mathlib |
7b0b2d8a1c53f909d74d89be39bf943104bf1082 | 94e33a31faa76775069b071adea97e86e218a8ee | /src/ring_theory/tensor_product.lean | 23ab3776198249c559dfefc307bff6266157fd0b | [
"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 | 31,216 | lean | /-
Copyright (c) 2020 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison, Johan Commelin
-/
import linear_algebra.tensor_product_basis
import ring_theory.adjoin.basic
/-!
# The tensor product of R-algebras
Let `R` be a (semi)ring and `A` an `R`-algebra.
In this file we:
- Define the `A`-module structure on `A ⊗ M`, for an `R`-module `M`.
- Define the `R`-algebra structure on `A ⊗ B`, for another `R`-algebra `B`.
and provide the structure isomorphisms
* `R ⊗[R] A ≃ₐ[R] A`
* `A ⊗[R] R ≃ₐ[R] A`
* `A ⊗[R] B ≃ₐ[R] B ⊗[R] A`
* `((A ⊗[R] B) ⊗[R] C) ≃ₐ[R] (A ⊗[R] (B ⊗[R] C))`
## Main declaration
- `linear_map.base_change A f` is the `A`-linear map `A ⊗ f`, for an `R`-linear map `f`.
## Implementation notes
The heterobasic definitions below such as:
* `tensor_product.algebra_tensor_module.curry`
* `tensor_product.algebra_tensor_module.uncurry`
* `tensor_product.algebra_tensor_module.lcurry`
* `tensor_product.algebra_tensor_module.lift`
* `tensor_product.algebra_tensor_module.lift.equiv`
* `tensor_product.algebra_tensor_module.mk`
* `tensor_product.algebra_tensor_module.assoc`
are just more general versions of the definitions already in `linear_algebra/tensor_product`. We
could thus consider replacing the less general definitions with these ones. If we do this, we
probably should still implement the less general ones as abbreviations to the more general ones with
fewer type arguments.
-/
universes u v₁ v₂ v₃ v₄
open_locale tensor_product
open tensor_product
namespace tensor_product
variables {R A M N P : Type*}
/-!
### The `A`-module structure on `A ⊗[R] M`
-/
open linear_map
open algebra (lsmul)
namespace algebra_tensor_module
section semiring
variables [comm_semiring R] [semiring A] [algebra R A]
variables [add_comm_monoid M] [module R M] [module A M] [is_scalar_tower R A M]
variables [add_comm_monoid N] [module R N]
variables [add_comm_monoid P] [module R P] [module A P] [is_scalar_tower R A P]
lemma smul_eq_lsmul_rtensor (a : A) (x : M ⊗[R] N) : a • x = (lsmul R M a).rtensor N x := rfl
/-- Heterobasic version of `tensor_product.curry`:
Given a linear map `M ⊗[R] N →[A] P`, compose it with the canonical
bilinear map `M →[A] N →[R] M ⊗[R] N` to form a bilinear map `M →[A] N →[R] P`. -/
@[simps] def curry (f : (M ⊗[R] N) →ₗ[A] P) : M →ₗ[A] (N →ₗ[R] P) :=
{ map_smul' := λ c x, linear_map.ext $ λ y, f.map_smul c (x ⊗ₜ y),
.. curry (f.restrict_scalars R) }
lemma restrict_scalars_curry (f : (M ⊗[R] N) →ₗ[A] P) :
restrict_scalars R (curry f) = curry (f.restrict_scalars R) :=
rfl
/-- Just as `tensor_product.ext` is marked `ext` instead of `tensor_product.ext'`, this is
a better `ext` lemma than `tensor_product.algebra_tensor_module.ext` below.
See note [partially-applied ext lemmas]. -/
@[ext] lemma curry_injective :
function.injective (curry : (M ⊗ N →ₗ[A] P) → (M →ₗ[A] N →ₗ[R] P)) :=
λ x y h, linear_map.restrict_scalars_injective R $ curry_injective $
(congr_arg (linear_map.restrict_scalars R) h : _)
theorem ext {g h : (M ⊗[R] N) →ₗ[A] P}
(H : ∀ x y, g (x ⊗ₜ y) = h (x ⊗ₜ y)) : g = h :=
curry_injective $ linear_map.ext₂ H
end semiring
section comm_semiring
variables [comm_semiring R] [comm_semiring A] [algebra R A]
variables [add_comm_monoid M] [module R M] [module A M] [is_scalar_tower R A M]
variables [add_comm_monoid N] [module R N]
variables [add_comm_monoid P] [module R P] [module A P] [is_scalar_tower R A P]
/-- Heterobasic version of `tensor_product.lift`:
Constructing a linear map `M ⊗[R] N →[A] P` given a bilinear map `M →[A] N →[R] P` with the
property that its composition with the canonical bilinear map `M →[A] N →[R] M ⊗[R] N` is
the given bilinear map `M →[A] N →[R] P`. -/
@[simps] def lift (f : M →ₗ[A] (N →ₗ[R] P)) : (M ⊗[R] N) →ₗ[A] P :=
{ map_smul' := λ c, show ∀ x : M ⊗[R] N, (lift (f.restrict_scalars R)).comp (lsmul R _ c) x =
(lsmul R _ c).comp (lift (f.restrict_scalars R)) x,
from ext_iff.1 $ tensor_product.ext' $ λ x y,
by simp only [comp_apply, algebra.lsmul_coe, smul_tmul', lift.tmul, coe_restrict_scalars_eq_coe,
f.map_smul, smul_apply],
.. lift (f.restrict_scalars R) }
@[simp] lemma lift_tmul (f : M →ₗ[A] (N →ₗ[R] P)) (x : M) (y : N) :
lift f (x ⊗ₜ y) = f x y :=
lift.tmul' x y
variables (R A M N P)
/-- Heterobasic version of `tensor_product.uncurry`:
Linearly constructing a linear map `M ⊗[R] N →[A] P` given a bilinear map `M →[A] N →[R] P`
with the property that its composition with the canonical bilinear map `M →[A] N →[R] M ⊗[R] N` is
the given bilinear map `M →[A] N →[R] P`. -/
@[simps] def uncurry : (M →ₗ[A] (N →ₗ[R] P)) →ₗ[A] ((M ⊗[R] N) →ₗ[A] P) :=
{ to_fun := lift,
map_add' := λ f g, ext $ λ x y, by simp only [lift_tmul, add_apply],
map_smul' := λ c f, ext $ λ x y, by simp only [lift_tmul, smul_apply, ring_hom.id_apply] }
/-- Heterobasic version of `tensor_product.lcurry`:
Given a linear map `M ⊗[R] N →[A] P`, compose it with the canonical
bilinear map `M →[A] N →[R] M ⊗[R] N` to form a bilinear map `M →[A] N →[R] P`. -/
@[simps] def lcurry : ((M ⊗[R] N) →ₗ[A] P) →ₗ[A] (M →ₗ[A] (N →ₗ[R] P)) :=
{ to_fun := curry,
map_add' := λ f g, rfl,
map_smul' := λ c f, rfl }
/-- Heterobasic version of `tensor_product.lift.equiv`:
A linear equivalence constructing a linear map `M ⊗[R] N →[A] P` given a
bilinear map `M →[A] N →[R] P` with the property that its composition with the
canonical bilinear map `M →[A] N →[R] M ⊗[R] N` is the given bilinear map `M →[A] N →[R] P`. -/
def lift.equiv : (M →ₗ[A] (N →ₗ[R] P)) ≃ₗ[A] ((M ⊗[R] N) →ₗ[A] P) :=
linear_equiv.of_linear (uncurry R A M N P) (lcurry R A M N P)
(linear_map.ext $ λ f, ext $ λ x y, lift_tmul _ x y)
(linear_map.ext $ λ f, linear_map.ext $ λ x, linear_map.ext $ λ y, lift_tmul f x y)
variables (R A M N P)
/-- Heterobasic version of `tensor_product.mk`:
The canonical bilinear map `M →[A] N →[R] M ⊗[R] N`. -/
@[simps] def mk : M →ₗ[A] N →ₗ[R] M ⊗[R] N :=
{ map_smul' := λ c x, rfl,
.. mk R M N }
local attribute [ext] tensor_product.ext
/-- Heterobasic version of `tensor_product.assoc`:
Linear equivalence between `(M ⊗[A] N) ⊗[R] P` and `M ⊗[A] (N ⊗[R] P)`. -/
def assoc : ((M ⊗[A] P) ⊗[R] N) ≃ₗ[A] (M ⊗[A] (P ⊗[R] N)) :=
linear_equiv.of_linear
(lift $ tensor_product.uncurry A _ _ _ $ comp (lcurry R A _ _ _) $
tensor_product.mk A M (P ⊗[R] N))
(tensor_product.uncurry A _ _ _ $ comp (uncurry R A _ _ _) $
by { apply tensor_product.curry, exact (mk R A _ _) })
(by { ext, refl, })
(by { ext, simp only [curry_apply, tensor_product.curry_apply, mk_apply, tensor_product.mk_apply,
uncurry_apply, tensor_product.uncurry_apply, id_apply, lift_tmul, compr₂_apply,
restrict_scalars_apply, function.comp_app, to_fun_eq_coe, lcurry_apply,
linear_map.comp_apply] })
end comm_semiring
end algebra_tensor_module
end tensor_product
namespace linear_map
open tensor_product
/-!
### The base-change of a linear map of `R`-modules to a linear map of `A`-modules
-/
section semiring
variables {R A B M N : Type*} [comm_semiring R]
variables [semiring A] [algebra R A] [semiring B] [algebra R B]
variables [add_comm_monoid M] [module R M] [add_comm_monoid N] [module R N]
variables (r : R) (f g : M →ₗ[R] N)
variables (A)
/-- `base_change A f` for `f : M →ₗ[R] N` is the `A`-linear map `A ⊗[R] M →ₗ[A] A ⊗[R] N`. -/
def base_change (f : M →ₗ[R] N) : A ⊗[R] M →ₗ[A] A ⊗[R] N :=
{ to_fun := f.ltensor A,
map_add' := (f.ltensor A).map_add,
map_smul' := λ a x,
show (f.ltensor A) (rtensor M (algebra.lmul R A a) x) =
(rtensor N ((algebra.lmul R A) a)) ((ltensor A f) x),
by { rw [← comp_apply, ← comp_apply],
simp only [ltensor_comp_rtensor, rtensor_comp_ltensor] } }
variables {A}
@[simp] lemma base_change_tmul (a : A) (x : M) :
f.base_change A (a ⊗ₜ x) = a ⊗ₜ (f x) := rfl
lemma base_change_eq_ltensor :
(f.base_change A : A ⊗ M → A ⊗ N) = f.ltensor A := rfl
@[simp] lemma base_change_add :
(f + g).base_change A = f.base_change A + g.base_change A :=
by { ext, simp [base_change_eq_ltensor], }
@[simp] lemma base_change_zero : base_change A (0 : M →ₗ[R] N) = 0 :=
by { ext, simp [base_change_eq_ltensor], }
@[simp] lemma base_change_smul : (r • f).base_change A = r • (f.base_change A) :=
by { ext, simp [base_change_tmul], }
variables (R A M N)
/-- `base_change` as a linear map. -/
@[simps] def base_change_hom : (M →ₗ[R] N) →ₗ[R] A ⊗[R] M →ₗ[A] A ⊗[R] N :=
{ to_fun := base_change A,
map_add' := base_change_add,
map_smul' := base_change_smul }
end semiring
section ring
variables {R A B M N : Type*} [comm_ring R]
variables [ring A] [algebra R A] [ring B] [algebra R B]
variables [add_comm_group M] [module R M] [add_comm_group N] [module R N]
variables (f g : M →ₗ[R] N)
@[simp] lemma base_change_sub :
(f - g).base_change A = f.base_change A - g.base_change A :=
by { ext, simp [base_change_eq_ltensor], }
@[simp] lemma base_change_neg : (-f).base_change A = -(f.base_change A) :=
by { ext, simp [base_change_eq_ltensor], }
end ring
end linear_map
namespace algebra
namespace tensor_product
section semiring
variables {R : Type u} [comm_semiring R]
variables {A : Type v₁} [semiring A] [algebra R A]
variables {B : Type v₂} [semiring B] [algebra R B]
/-!
### The `R`-algebra structure on `A ⊗[R] B`
-/
/--
(Implementation detail)
The multiplication map on `A ⊗[R] B`,
for a fixed pure tensor in the first argument,
as an `R`-linear map.
-/
def mul_aux (a₁ : A) (b₁ : B) : (A ⊗[R] B) →ₗ[R] (A ⊗[R] B) :=
tensor_product.map (lmul_left R a₁) (lmul_left R b₁)
@[simp]
lemma mul_aux_apply (a₁ a₂ : A) (b₁ b₂ : B) :
(mul_aux a₁ b₁) (a₂ ⊗ₜ[R] b₂) = (a₁ * a₂) ⊗ₜ[R] (b₁ * b₂) :=
rfl
/--
(Implementation detail)
The multiplication map on `A ⊗[R] B`,
as an `R`-bilinear map.
-/
def mul : (A ⊗[R] B) →ₗ[R] (A ⊗[R] B) →ₗ[R] (A ⊗[R] B) :=
tensor_product.lift $ linear_map.mk₂ R mul_aux
(λ x₁ x₂ y, tensor_product.ext' $ λ x' y',
by simp only [mul_aux_apply, linear_map.add_apply, add_mul, add_tmul])
(λ c x y, tensor_product.ext' $ λ x' y',
by simp only [mul_aux_apply, linear_map.smul_apply, smul_tmul', smul_mul_assoc])
(λ x y₁ y₂, tensor_product.ext' $ λ x' y',
by simp only [mul_aux_apply, linear_map.add_apply, add_mul, tmul_add])
(λ c x y, tensor_product.ext' $ λ x' y',
by simp only [mul_aux_apply, linear_map.smul_apply, smul_tmul, smul_tmul', smul_mul_assoc])
@[simp]
lemma mul_apply (a₁ a₂ : A) (b₁ b₂ : B) :
mul (a₁ ⊗ₜ[R] b₁) (a₂ ⊗ₜ[R] b₂) = (a₁ * a₂) ⊗ₜ[R] (b₁ * b₂) :=
rfl
lemma mul_assoc' (mul : (A ⊗[R] B) →ₗ[R] (A ⊗[R] B) →ₗ[R] (A ⊗[R] B))
(h : ∀ (a₁ a₂ a₃ : A) (b₁ b₂ b₃ : B),
mul (mul (a₁ ⊗ₜ[R] b₁) (a₂ ⊗ₜ[R] b₂)) (a₃ ⊗ₜ[R] b₃) =
mul (a₁ ⊗ₜ[R] b₁) (mul (a₂ ⊗ₜ[R] b₂) (a₃ ⊗ₜ[R] b₃))) :
∀ (x y z : A ⊗[R] B), mul (mul x y) z = mul x (mul y z) :=
begin
intros,
apply tensor_product.induction_on x,
{ simp only [linear_map.map_zero, linear_map.zero_apply], },
apply tensor_product.induction_on y,
{ simp only [linear_map.map_zero, forall_const, linear_map.zero_apply], },
apply tensor_product.induction_on z,
{ simp only [linear_map.map_zero, forall_const], },
{ intros, simp only [h], },
{ intros, simp only [linear_map.map_add, *], },
{ intros, simp only [linear_map.map_add, *, linear_map.add_apply], },
{ intros, simp only [linear_map.map_add, *, linear_map.add_apply], },
end
lemma mul_assoc (x y z : A ⊗[R] B) : mul (mul x y) z = mul x (mul y z) :=
mul_assoc' mul (by { intros, simp only [mul_apply, mul_assoc], }) x y z
lemma one_mul (x : A ⊗[R] B) : mul (1 ⊗ₜ 1) x = x :=
begin
apply tensor_product.induction_on x;
simp {contextual := tt},
end
lemma mul_one (x : A ⊗[R] B) : mul x (1 ⊗ₜ 1) = x :=
begin
apply tensor_product.induction_on x;
simp {contextual := tt},
end
instance : has_one (A ⊗[R] B) :=
{ one := 1 ⊗ₜ 1 }
instance : add_monoid_with_one (A ⊗[R] B) := add_monoid_with_one.unary
instance : semiring (A ⊗[R] B) :=
{ zero := 0,
add := (+),
one := 1,
mul := λ a b, mul a b,
one_mul := one_mul,
mul_one := mul_one,
mul_assoc := mul_assoc,
zero_mul := by simp,
mul_zero := by simp,
left_distrib := by simp,
right_distrib := by simp,
.. (by apply_instance : add_monoid_with_one (A ⊗[R] B)),
.. (by apply_instance : add_comm_monoid (A ⊗[R] B)) }.
lemma one_def : (1 : A ⊗[R] B) = (1 : A) ⊗ₜ (1 : B) := rfl
@[simp]
lemma tmul_mul_tmul (a₁ a₂ : A) (b₁ b₂ : B) :
(a₁ ⊗ₜ[R] b₁) * (a₂ ⊗ₜ[R] b₂) = (a₁ * a₂) ⊗ₜ[R] (b₁ * b₂) :=
rfl
@[simp]
lemma tmul_pow (a : A) (b : B) (k : ℕ) :
(a ⊗ₜ[R] b)^k = (a^k) ⊗ₜ[R] (b^k) :=
begin
induction k with k ih,
{ simp [one_def], },
{ simp [pow_succ, ih], }
end
/-- The ring morphism `A →+* A ⊗[R] B` sending `a` to `a ⊗ₜ 1`. -/
@[simps]
def include_left_ring_hom : A →+* A ⊗[R] B :=
{ to_fun := λ a, a ⊗ₜ 1,
map_zero' := by simp,
map_add' := by simp [add_tmul],
map_one' := rfl,
map_mul' := by simp }
variables {S : Type*} [comm_semiring S] [algebra R S] [algebra S A] [is_scalar_tower R S A]
instance left_algebra : algebra S (A ⊗[R] B) :=
{ commutes' := λ r x,
begin
apply tensor_product.induction_on x,
{ simp, },
{ intros a b, dsimp, rw [algebra.commutes, _root_.mul_one, _root_.one_mul], },
{ intros y y' h h', dsimp at h h' ⊢, simp only [mul_add, add_mul, h, h'], },
end,
smul_def' := λ r x,
begin
apply tensor_product.induction_on x,
{ simp [smul_zero], },
{ intros a b, dsimp, rw [tensor_product.smul_tmul', algebra.smul_def r a, _root_.one_mul] },
{ intros, dsimp, simp [smul_add, mul_add, *], },
end,
.. tensor_product.include_left_ring_hom.comp (algebra_map S A),
.. (by apply_instance : module S (A ⊗[R] B)) }.
-- This is for the `undergrad.yaml` list.
/-- The tensor product of two `R`-algebras is an `R`-algebra. -/
instance : algebra R (A ⊗[R] B) := infer_instance
@[simp]
lemma algebra_map_apply (r : S) :
(algebra_map S (A ⊗[R] B)) r = ((algebra_map S A) r) ⊗ₜ 1 := rfl
instance : is_scalar_tower R S (A ⊗[R] B) := ⟨λ a b c, by simp⟩
variables {C : Type v₃} [semiring C] [algebra R C]
@[ext]
theorem ext {g h : (A ⊗[R] B) →ₐ[R] C}
(H : ∀ a b, g (a ⊗ₜ b) = h (a ⊗ₜ b)) : g = h :=
begin
apply @alg_hom.to_linear_map_injective R (A ⊗[R] B) C _ _ _ _ _ _ _ _,
ext,
simp [H],
end
/-- The `R`-algebra morphism `A →ₐ[R] A ⊗[R] B` sending `a` to `a ⊗ₜ 1`. -/
def include_left : A →ₐ[R] A ⊗[R] B :=
{ commutes' := by simp,
..include_left_ring_hom }
@[simp]
lemma include_left_apply (a : A) : (include_left : A →ₐ[R] A ⊗[R] B) a = a ⊗ₜ 1 := rfl
/-- The algebra morphism `B →ₐ[R] A ⊗[R] B` sending `b` to `1 ⊗ₜ b`. -/
def include_right : B →ₐ[R] A ⊗[R] B :=
{ to_fun := λ b, 1 ⊗ₜ b,
map_zero' := by simp,
map_add' := by simp [tmul_add],
map_one' := rfl,
map_mul' := by simp,
commutes' := λ r,
begin
simp only [algebra_map_apply],
transitivity r • ((1 : A) ⊗ₜ[R] (1 : B)),
{ rw [←tmul_smul, algebra.smul_def], simp, },
{ simp [algebra.smul_def], },
end, }
@[simp]
lemma include_right_apply (b : B) : (include_right : B →ₐ[R] A ⊗[R] B) b = 1 ⊗ₜ b := rfl
end semiring
section ring
variables {R : Type u} [comm_ring R]
variables {A : Type v₁} [ring A] [algebra R A]
variables {B : Type v₂} [ring B] [algebra R B]
instance : ring (A ⊗[R] B) :=
{ .. (by apply_instance : add_comm_group (A ⊗[R] B)),
.. (by apply_instance : semiring (A ⊗[R] B)) }.
end ring
section comm_ring
variables {R : Type u} [comm_ring R]
variables {A : Type v₁} [comm_ring A] [algebra R A]
variables {B : Type v₂} [comm_ring B] [algebra R B]
instance : comm_ring (A ⊗[R] B) :=
{ mul_comm := λ x y,
begin
apply tensor_product.induction_on x,
{ simp, },
{ intros a₁ b₁,
apply tensor_product.induction_on y,
{ simp, },
{ intros a₂ b₂,
simp [mul_comm], },
{ intros a₂ b₂ ha hb,
simp [mul_add, add_mul, ha, hb], }, },
{ intros x₁ x₂ h₁ h₂,
simp [mul_add, add_mul, h₁, h₂], },
end
.. (by apply_instance : ring (A ⊗[R] B)) }.
end comm_ring
/--
Verify that typeclass search finds the ring structure on `A ⊗[ℤ] B`
when `A` and `B` are merely rings, by treating both as `ℤ`-algebras.
-/
example {A : Type v₁} [ring A] {B : Type v₂} [ring B] : ring (A ⊗[ℤ] B) :=
by apply_instance
/--
Verify that typeclass search finds the comm_ring structure on `A ⊗[ℤ] B`
when `A` and `B` are merely comm_rings, by treating both as `ℤ`-algebras.
-/
example {A : Type v₁} [comm_ring A] {B : Type v₂} [comm_ring B] : comm_ring (A ⊗[ℤ] B) :=
by apply_instance
/-!
We now build the structure maps for the symmetric monoidal category of `R`-algebras.
-/
section monoidal
section
variables {R : Type u} [comm_semiring R]
variables {A : Type v₁} [semiring A] [algebra R A]
variables {B : Type v₂} [semiring B] [algebra R B]
variables {C : Type v₃} [semiring C] [algebra R C]
variables {D : Type v₄} [semiring D] [algebra R D]
/--
Build an algebra morphism from a linear map out of a tensor product,
and evidence of multiplicativity on pure tensors.
-/
def alg_hom_of_linear_map_tensor_product
(f : A ⊗[R] B →ₗ[R] C)
(w₁ : ∀ (a₁ a₂ : A) (b₁ b₂ : B), f ((a₁ * a₂) ⊗ₜ (b₁ * b₂)) = f (a₁ ⊗ₜ b₁) * f (a₂ ⊗ₜ b₂))
(w₂ : ∀ r, f ((algebra_map R A) r ⊗ₜ[R] 1) = (algebra_map R C) r):
A ⊗[R] B →ₐ[R] C :=
{ map_one' := by rw [←(algebra_map R C).map_one, ←w₂, (algebra_map R A).map_one]; refl,
map_zero' := by rw [linear_map.to_fun_eq_coe, map_zero],
map_mul' := λ x y, by
{ rw linear_map.to_fun_eq_coe,
apply tensor_product.induction_on x,
{ rw [zero_mul, map_zero, zero_mul] },
{ intros a₁ b₁,
apply tensor_product.induction_on y,
{ rw [mul_zero, map_zero, mul_zero] },
{ intros a₂ b₂,
rw [tmul_mul_tmul, w₁] },
{ intros x₁ x₂ h₁ h₂,
rw [mul_add, map_add, map_add, mul_add, h₁, h₂] } },
{ intros x₁ x₂ h₁ h₂,
rw [add_mul, map_add, map_add, add_mul, h₁, h₂] } },
commutes' := λ r, by rw [linear_map.to_fun_eq_coe, algebra_map_apply, w₂],
.. f }
@[simp]
lemma alg_hom_of_linear_map_tensor_product_apply (f w₁ w₂ x) :
(alg_hom_of_linear_map_tensor_product f w₁ w₂ : A ⊗[R] B →ₐ[R] C) x = f x := rfl
/--
Build an algebra equivalence from a linear equivalence out of a tensor product,
and evidence of multiplicativity on pure tensors.
-/
def alg_equiv_of_linear_equiv_tensor_product
(f : A ⊗[R] B ≃ₗ[R] C)
(w₁ : ∀ (a₁ a₂ : A) (b₁ b₂ : B), f ((a₁ * a₂) ⊗ₜ (b₁ * b₂)) = f (a₁ ⊗ₜ b₁) * f (a₂ ⊗ₜ b₂))
(w₂ : ∀ r, f ((algebra_map R A) r ⊗ₜ[R] 1) = (algebra_map R C) r):
A ⊗[R] B ≃ₐ[R] C :=
{ .. alg_hom_of_linear_map_tensor_product (f : A ⊗[R] B →ₗ[R] C) w₁ w₂,
.. f }
@[simp]
lemma alg_equiv_of_linear_equiv_tensor_product_apply (f w₁ w₂ x) :
(alg_equiv_of_linear_equiv_tensor_product f w₁ w₂ : A ⊗[R] B ≃ₐ[R] C) x = f x := rfl
/--
Build an algebra equivalence from a linear equivalence out of a triple tensor product,
and evidence of multiplicativity on pure tensors.
-/
def alg_equiv_of_linear_equiv_triple_tensor_product
(f : ((A ⊗[R] B) ⊗[R] C) ≃ₗ[R] D)
(w₁ : ∀ (a₁ a₂ : A) (b₁ b₂ : B) (c₁ c₂ : C),
f ((a₁ * a₂) ⊗ₜ (b₁ * b₂) ⊗ₜ (c₁ * c₂)) = f (a₁ ⊗ₜ b₁ ⊗ₜ c₁) * f (a₂ ⊗ₜ b₂ ⊗ₜ c₂))
(w₂ : ∀ r, f (((algebra_map R A) r ⊗ₜ[R] (1 : B)) ⊗ₜ[R] (1 : C)) = (algebra_map R D) r) :
(A ⊗[R] B) ⊗[R] C ≃ₐ[R] D :=
{ to_fun := f,
map_mul' := λ x y,
begin
apply tensor_product.induction_on x,
{ simp only [map_zero, zero_mul] },
{ intros ab₁ c₁,
apply tensor_product.induction_on y,
{ simp only [map_zero, mul_zero] },
{ intros ab₂ c₂,
apply tensor_product.induction_on ab₁,
{ simp only [zero_tmul, map_zero, zero_mul] },
{ intros a₁ b₁,
apply tensor_product.induction_on ab₂,
{ simp only [zero_tmul, map_zero, mul_zero] },
{ intros, simp only [tmul_mul_tmul, w₁] },
{ intros x₁ x₂ h₁ h₂,
simp only [tmul_mul_tmul] at h₁ h₂,
simp only [tmul_mul_tmul, mul_add, add_tmul, map_add, h₁, h₂] } },
{ intros x₁ x₂ h₁ h₂,
simp only [tmul_mul_tmul] at h₁ h₂,
simp only [tmul_mul_tmul, add_mul, add_tmul, map_add, h₁, h₂] } },
{ intros x₁ x₂ h₁ h₂,
simp only [tmul_mul_tmul, map_add, mul_add, add_mul, h₁, h₂], }, },
{ intros x₁ x₂ h₁ h₂,
simp only [tmul_mul_tmul, map_add, mul_add, add_mul, h₁, h₂], }
end,
commutes' := λ r, by simp [w₂],
.. f }
@[simp]
lemma alg_equiv_of_linear_equiv_triple_tensor_product_apply (f w₁ w₂ x) :
(alg_equiv_of_linear_equiv_triple_tensor_product f w₁ w₂ : (A ⊗[R] B) ⊗[R] C ≃ₐ[R] D) x = f x :=
rfl
end
variables {R : Type u} [comm_semiring R]
variables {A : Type v₁} [semiring A] [algebra R A]
variables {B : Type v₂} [semiring B] [algebra R B]
variables {C : Type v₃} [semiring C] [algebra R C]
variables {D : Type v₄} [semiring D] [algebra R D]
section
variables (R A)
/--
The base ring is a left identity for the tensor product of algebra, up to algebra isomorphism.
-/
protected def lid : R ⊗[R] A ≃ₐ[R] A :=
alg_equiv_of_linear_equiv_tensor_product (tensor_product.lid R A)
(by simp [mul_smul]) (by simp [algebra.smul_def])
@[simp] theorem lid_tmul (r : R) (a : A) :
(tensor_product.lid R A : (R ⊗ A → A)) (r ⊗ₜ a) = r • a :=
by simp [tensor_product.lid]
/--
The base ring is a right identity for the tensor product of algebra, up to algebra isomorphism.
-/
protected def rid : A ⊗[R] R ≃ₐ[R] A :=
alg_equiv_of_linear_equiv_tensor_product (tensor_product.rid R A)
(by simp [mul_smul]) (by simp [algebra.smul_def])
@[simp] theorem rid_tmul (r : R) (a : A) :
(tensor_product.rid R A : (A ⊗ R → A)) (a ⊗ₜ r) = r • a :=
by simp [tensor_product.rid]
section
variables (R A B)
/--
The tensor product of R-algebras is commutative, up to algebra isomorphism.
-/
protected def comm : A ⊗[R] B ≃ₐ[R] B ⊗[R] A :=
alg_equiv_of_linear_equiv_tensor_product (tensor_product.comm R A B)
(by simp)
(λ r, begin
transitivity r • ((1 : B) ⊗ₜ[R] (1 : A)),
{ rw [←tmul_smul, algebra.smul_def], simp, },
{ simp [algebra.smul_def], },
end)
@[simp]
theorem comm_tmul (a : A) (b : B) :
(tensor_product.comm R A B : (A ⊗[R] B → B ⊗[R] A)) (a ⊗ₜ b) = (b ⊗ₜ a) :=
by simp [tensor_product.comm]
lemma adjoin_tmul_eq_top : adjoin R {t : A ⊗[R] B | ∃ a b, a ⊗ₜ[R] b = t} = ⊤ :=
top_le_iff.mp $ (top_le_iff.mpr $ span_tmul_eq_top R A B).trans (span_le_adjoin R _)
end
section
variables {R A B C}
lemma assoc_aux_1 (a₁ a₂ : A) (b₁ b₂ : B) (c₁ c₂ : C) :
(tensor_product.assoc R A B C) (((a₁ * a₂) ⊗ₜ[R] (b₁ * b₂)) ⊗ₜ[R] (c₁ * c₂)) =
(tensor_product.assoc R A B C) ((a₁ ⊗ₜ[R] b₁) ⊗ₜ[R] c₁) *
(tensor_product.assoc R A B C) ((a₂ ⊗ₜ[R] b₂) ⊗ₜ[R] c₂) :=
rfl
lemma assoc_aux_2 (r : R) :
(tensor_product.assoc R A B C) (((algebra_map R A) r ⊗ₜ[R] 1) ⊗ₜ[R] 1) =
(algebra_map R (A ⊗ (B ⊗ C))) r := rfl
variables (R A B C)
/-- The associator for tensor product of R-algebras, as an algebra isomorphism. -/
protected def assoc : ((A ⊗[R] B) ⊗[R] C) ≃ₐ[R] (A ⊗[R] (B ⊗[R] C)) :=
alg_equiv_of_linear_equiv_triple_tensor_product
(tensor_product.assoc.{u v₁ v₂ v₃} R A B C : (A ⊗ B ⊗ C) ≃ₗ[R] (A ⊗ (B ⊗ C)))
(@algebra.tensor_product.assoc_aux_1.{u v₁ v₂ v₃} R _ A _ _ B _ _ C _ _)
(@algebra.tensor_product.assoc_aux_2.{u v₁ v₂ v₃} R _ A _ _ B _ _ C _ _)
variables {R A B C}
@[simp] theorem assoc_tmul (a : A) (b : B) (c : C) :
((tensor_product.assoc R A B C) :
(A ⊗[R] B) ⊗[R] C → A ⊗[R] (B ⊗[R] C)) ((a ⊗ₜ b) ⊗ₜ c) = a ⊗ₜ (b ⊗ₜ c) :=
rfl
end
variables {R A B C D}
/-- The tensor product of a pair of algebra morphisms. -/
def map (f : A →ₐ[R] B) (g : C →ₐ[R] D) : A ⊗[R] C →ₐ[R] B ⊗[R] D :=
alg_hom_of_linear_map_tensor_product
(tensor_product.map f.to_linear_map g.to_linear_map)
(by simp)
(by simp [alg_hom.commutes])
@[simp] theorem map_tmul (f : A →ₐ[R] B) (g : C →ₐ[R] D) (a : A) (c : C) :
map f g (a ⊗ₜ c) = f a ⊗ₜ g c :=
rfl
@[simp] lemma map_comp_include_left (f : A →ₐ[R] B) (g : C →ₐ[R] D) :
(map f g).comp include_left = include_left.comp f := alg_hom.ext $ by simp
@[simp] lemma map_comp_include_right (f : A →ₐ[R] B) (g : C →ₐ[R] D) :
(map f g).comp include_right = include_right.comp g := alg_hom.ext $ by simp
lemma map_range (f : A →ₐ[R] B) (g : C →ₐ[R] D) :
(map f g).range = (include_left.comp f).range ⊔ (include_right.comp g).range :=
begin
apply le_antisymm,
{ rw [←map_top, ←adjoin_tmul_eq_top, ←adjoin_image, adjoin_le_iff],
rintros _ ⟨_, ⟨a, b, rfl⟩, rfl⟩,
rw [map_tmul, ←_root_.mul_one (f a), ←_root_.one_mul (g b), ←tmul_mul_tmul],
exact mul_mem_sup (alg_hom.mem_range_self _ a) (alg_hom.mem_range_self _ b) },
{ rw [←map_comp_include_left f g, ←map_comp_include_right f g],
exact sup_le (alg_hom.range_comp_le_range _ _) (alg_hom.range_comp_le_range _ _) },
end
/--
Construct an isomorphism between tensor products of R-algebras
from isomorphisms between the tensor factors.
-/
def congr (f : A ≃ₐ[R] B) (g : C ≃ₐ[R] D) : A ⊗[R] C ≃ₐ[R] B ⊗[R] D :=
alg_equiv.of_alg_hom (map f g) (map f.symm g.symm)
(ext $ λ b d, by simp)
(ext $ λ a c, by simp)
@[simp]
lemma congr_apply (f : A ≃ₐ[R] B) (g : C ≃ₐ[R] D) (x) :
congr f g x = (map (f : A →ₐ[R] B) (g : C →ₐ[R] D)) x := rfl
@[simp]
lemma congr_symm_apply (f : A ≃ₐ[R] B) (g : C ≃ₐ[R] D) (x) :
(congr f g).symm x = (map (f.symm : B →ₐ[R] A) (g.symm : D →ₐ[R] C)) x := rfl
end
end monoidal
section
variables {R A B S : Type*} [comm_semiring R] [semiring A] [semiring B] [comm_semiring S]
variables [algebra R A] [algebra R B] [algebra R S]
variables (f : A →ₐ[R] S) (g : B →ₐ[R] S)
variables (R)
/-- `algebra.lmul'` is an alg_hom on commutative rings. -/
def lmul' : S ⊗[R] S →ₐ[R] S :=
alg_hom_of_linear_map_tensor_product (algebra.lmul' R)
(λ a₁ a₂ b₁ b₂, by simp only [algebra.lmul'_apply, mul_mul_mul_comm])
(λ r, by simp only [algebra.lmul'_apply, _root_.mul_one])
variables {R}
lemma lmul'_to_linear_map : (lmul' R : _ →ₐ[R] S).to_linear_map = algebra.lmul' R := rfl
@[simp] lemma lmul'_apply_tmul (a b : S) : lmul' R (a ⊗ₜ[R] b) = a * b := lmul'_apply
@[simp]
lemma lmul'_comp_include_left : (lmul' R : _ →ₐ[R] S).comp include_left = alg_hom.id R S :=
alg_hom.ext $ λ _, (lmul'_apply_tmul _ _).trans (_root_.mul_one _)
@[simp]
lemma lmul'_comp_include_right : (lmul' R : _ →ₐ[R] S).comp include_right = alg_hom.id R S :=
alg_hom.ext $ λ _, (lmul'_apply_tmul _ _).trans (_root_.one_mul _)
/--
If `S` is commutative, for a pair of morphisms `f : A →ₐ[R] S`, `g : B →ₐ[R] S`,
We obtain a map `A ⊗[R] B →ₐ[R] S` that commutes with `f`, `g` via `a ⊗ b ↦ f(a) * g(b)`.
-/
def product_map : A ⊗[R] B →ₐ[R] S := (lmul' R).comp (tensor_product.map f g)
@[simp] lemma product_map_apply_tmul (a : A) (b : B) : product_map f g (a ⊗ₜ b) = f a * g b :=
by { unfold product_map lmul', simp }
lemma product_map_left_apply (a : A) :
product_map f g ((include_left : A →ₐ[R] A ⊗ B) a) = f a := by simp
@[simp] lemma product_map_left : (product_map f g).comp include_left = f := alg_hom.ext $ by simp
lemma product_map_right_apply (b : B) : product_map f g (include_right b) = g b := by simp
@[simp] lemma product_map_right : (product_map f g).comp include_right = g := alg_hom.ext $ by simp
lemma product_map_range : (product_map f g).range = f.range ⊔ g.range :=
by rw [product_map, alg_hom.range_comp, map_range, map_sup, ←alg_hom.range_comp,
←alg_hom.range_comp, ←alg_hom.comp_assoc, ←alg_hom.comp_assoc, lmul'_comp_include_left,
lmul'_comp_include_right, alg_hom.id_comp, alg_hom.id_comp]
end
section
variables {R A A' B S : Type*}
variables [comm_semiring R] [comm_semiring A] [semiring A'] [semiring B] [comm_semiring S]
variables [algebra R A] [algebra R A'] [algebra A A'] [is_scalar_tower R A A'] [algebra R B]
variables [algebra R S] [algebra A S] [is_scalar_tower R A S]
/-- If `A`, `B` are `R`-algebras, `A'` is an `A`-algebra, then the product map of `f : A' →ₐ[A] S`
and `g : B →ₐ[R] S` is an `A`-algebra homomorphism. -/
@[simps] def product_left_alg_hom (f : A' →ₐ[A] S) (g : B →ₐ[R] S) : A' ⊗[R] B →ₐ[A] S :=
{ commutes' := λ r, by { dsimp, simp },
..(product_map (f.restrict_scalars R) g).to_ring_hom }
end
end tensor_product
end algebra
namespace module
variables {R M N : Type*} [comm_semiring R]
variables [add_comm_monoid M] [add_comm_monoid N]
variables [module R M] [module R N]
/-- The algebra homomorphism from `End M ⊗ End N` to `End (M ⊗ N)` sending `f ⊗ₜ g` to
the `tensor_product.map f g`, the tensor product of the two maps. -/
def End_tensor_End_alg_hom : (End R M) ⊗[R] (End R N) →ₐ[R] End R (M ⊗[R] N) :=
begin
refine algebra.tensor_product.alg_hom_of_linear_map_tensor_product
(hom_tensor_hom_map R M N M N) _ _,
{ intros f₁ f₂ g₁ g₂,
simp only [hom_tensor_hom_map_apply, tensor_product.map_mul] },
{ intro r,
simp only [hom_tensor_hom_map_apply],
ext m n, simp [smul_tmul] }
end
lemma End_tensor_End_alg_hom_apply (f : End R M) (g : End R N) :
End_tensor_End_alg_hom (f ⊗ₜ[R] g) = tensor_product.map f g :=
by simp only [End_tensor_End_alg_hom,
algebra.tensor_product.alg_hom_of_linear_map_tensor_product_apply, hom_tensor_hom_map_apply]
end module
lemma subalgebra.finite_dimensional_sup {K L : Type*} [field K] [comm_ring L] [algebra K L]
(E1 E2 : subalgebra K L) [finite_dimensional K E1] [finite_dimensional K E2] :
finite_dimensional K ↥(E1 ⊔ E2) :=
begin
rw [←E1.range_val, ←E2.range_val, ←algebra.tensor_product.product_map_range],
exact (algebra.tensor_product.product_map E1.val E2.val).to_linear_map.finite_dimensional_range,
end
|
95aec22eda34ffe7d62115ec4657d0a2c2ff49c2 | b7f22e51856f4989b970961f794f1c435f9b8f78 | /tests/lean/run/rewriter17.lean | 6d448f0d4aa54725c37223943142b9844d1b9033 | [
"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 | 150 | lean | open nat
definition foo [irreducible] (x : nat) := x + 1
example (a b : nat) (H : foo a = b) : a + 1 = b :=
begin
rewrite ↓foo a,
exact H
end
|
0b83997014132d1ca42d2deaeb756545fded3d9a | b794ca1df49bc5a3bd3fd5552eed3bc4f63b8b93 | /src/mywork/lecture_8.lean | 84c191afdc5535d5c5b648d81a4977f94e54c3a1 | [] | no_license | akraisinger/cs2120f21 | 8235ac98375e04ffcec504cff5cab7833ee69e54 | 4ef83d7151bb6a284028092aa4f1d509c0eb8237 | refs/heads/main | 1,691,714,771,612 | 1,632,889,465,000 | 1,632,889,465,000 | 399,946,508 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 5,130 | lean | /-
my cool solution
theorem and_associative : ∀ (P Q R: Prop), (P ∧ Q) ∧ R → P ∧ (Q ∧ R) :=
begin
assume P Q R,
assume h,
apply and.intro _ _,
have pq : P ∧ Q := and.elim_left h,
exact (and.elim_left pq),
apply and.intro _ _,
apply and.elim_right (and.elim_left h),
apply and.elim_right h,
end
-/
-- the prof's example solution
theorem and_associative : ∀ (P Q R: Prop), (P ∧ Q) ∧ R → P ∧ (Q ∧ R) :=
begin
assume P Q R,
assume h,
have pq : P ∧ Q := and.elim_left h,
have p : P := and.elim_left pq,
have q : Q := and.elim_right pq,
have r : R := and.elim_right h,
exact and.intro p (and.intro q r),
end
/-
The or connective, ∨, in predicate logic
join any two propositions, P, Q, into a
larger proposition, P ∨ Q. This proposition
is judged as true if either (or both) P, Q
are true.
-/
/-
Introduction rules (two of them).
There are two ways to prove a proposition,
(P ∨ Q): with a proof of P, or with a proof
of Q. Either will do. We thus have two intro
rules for ∨. They are called the left and
right introduction rules.
The left one takes- a proof, let's say, p, of
the left proposition, P (from which it infers)
P along with the right proposition, Q, and then
returns a proof of P ∨ Q. The arguments are
actually given in the other order. The right
introduction rule thus takes the proposition,
P and a proof of the proposition, Q, and also
returns a proof of P ∨ Q.
Exercise: Suppose that it's true (and thus
that we we have a proof) that Joe chews gum.
Give an English proof of the proposition that
(Joe is tall) ∨ (Joe chews gum).
Proof: Apply the right introduction rule for
∨ to (1) our proof that Joe chews gum, and
(2) the proposition that Joe is tall. The
result is the proof we want, of the proposition
(Joe chews gum) ∨ (Joe is tall).
Exercise: Give an English language proof of:
(Joe is tall) ∨ (Joe chews gum).
-/
/-
In Lean, the rules are called or.intro_left
and or.intro_right.
-/
#check @or.intro_left
#check @or.intro_right
/-
In the preceding outputs, you can see that the
arguments that are required explicitly are in
parentheses, and the arguments whose values are
inferred from other arguments are given in {}.
-/
/-
Let's formalize our example in Lean.
-/
axioms (Joe_is_tall Joe_chews_gum : Prop)
axiom jcg: Joe_chews_gum -- proof of joe chews gum
theorem jcg_or_jit: Joe_chews_gum ∨ Joe_is_tall :=
or.intro_left Joe_is_tall jcg
/-
Exercise: Formalize our second version of this
proposition and a proof of it.
-/
/-
We thus have two inference rules (axioms) that we
can use to create a proof of a "disjunction".
(Q : Prop) {P : Prop} (p : P)
----------------------------- ∨ intro_left
pf : P ∨ Q
(P : Prop) {Q : Prop} (q : Q)
----------------------------- ∨ intro_right
pf : P ∨ Q
-/
/-
Suppose that if Joe is tall then he is funny,
that if Joe chews gum he is also funny, and that
Joe chews gum ∨ Joe is tall. What can we deduce
from these assumptions/facts?
-/
/-
You have just used the elimination rule for ∨.
Here it is a little more generally. Suppose P,
Q, and R are propositions, that P → R and Q → R,
and finally that P ∨ Q is true? What can we then
deduce? Why, R, of course!
{P Q R : Prop} (pq : P ∨ Q) (pr : P → R) (qr : Q → R)
-----------------------------------------------------
pf : R
-/
#check @or.elim
/-
Let's add a few assumptions and see this rule in action.
-/
axioms (P Q R : Prop) (pq : P ∨ Q) (pr : P → R) (qr : Q → R)
example : R := _
axioms
(Joe_is_funny : Prop)
(torf : Joe_is_tall ∨ Joe_chews_gum)
(tf: Joe_is_tall → Joe_is_funny)
(gf : Joe_chews_gum → Joe_is_funny)
example : Joe_is_funny :=
or.elim torf tf gf
/-
In English, under the given assumptions
(axioms, just above) we can prove that Joe
is funny *by cases*. We know that Joe chews
gum OR Joe is tall, so least one of these
cases must hold. Let's consider the cases
in turn.
Case 1: Suppose that (Joe is tall ∨ Joe
chews gum) is true because Joe is tall.
In this case we apply the fact that (Joe
is tall → Joe is funny) to the fact hat
(Joe is tall) to deduce that Joe is funny.
Exercise: What inference rule did we use
right there?
Case 2: The reasoning is similar. Suppose
the disjunction is true because Joe chews
gum. We can use "modus ponens", applying
the fact that (Joe chews gum → Joe is funny)
to deduce (Joe is funny).
Therefore Joe is funny *in either case*,
and *there are no other cases to consider*
so we can deduce that Joe is funny.
-/
/-
Here it is formally!
-/
-- By cases
example : Joe_is_funny :=
begin
cases torf, -- applies or.elim
apply tf h,
apply gf h,
end
-- Equivalent direct application of or.elim
example : Joe_is_funny :=
begin
apply or.elim torf _ _, -- applies or.elim
exact tf,
exact gf,
end
/-
Yay, now how about proving some theorems.
-/
/-
Problem #1: State precisely and prove that
∨ is commutative, in English then formally.
-/
/-
Problem #2: State precisely and prove that ∨
is associative, first in English then formally.
-/ |
c5ee5a4dbc3923f825b182c34005500c43b44f3e | 2d34dfb0a1cc250584282618dc10ea03d3fa858e | /src/for_mathlib/continuous_map.lean | 98c531fcb0de8c6a67de18f7325a6c85101c5a96 | [] | no_license | zeta1999/lean-liquid | 61e294ec5adae959d8ee1b65d015775484ff58c2 | 96bb0fa3afc3b451bcd1fb7d974348de2f290541 | refs/heads/master | 1,676,579,150,248 | 1,610,771,445,000 | 1,610,771,445,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 253 | lean | import topology.continuous_map
namespace continuous_map
variables {X Y : Type*} [topological_space X] [topological_space Y]
@[simp] lemma coe_mk (f : X → Y) (h : continuous f) :
⇑(⟨f, h⟩ : continuous_map X Y) = f := rfl
end continuous_map
|
2de4cc425e1a4a9169a7b09bbbf1102dbf7b209f | bbecf0f1968d1fba4124103e4f6b55251d08e9c4 | /src/data/nat/pairing.lean | 888b07fb1031a857883f3de860787afd23ca4da8 | [
"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 | 5,008 | 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 data.nat.sqrt
import data.set.lattice
/-!
# Naturals pairing function
This file defines a pairing function for the naturals as follows:
```text
0 1 4 9 16
2 3 5 10 17
6 7 8 11 18
12 13 14 15 19
20 21 22 23 24
```
It has the advantage of being monotone in both directions and sending `⟦0, n^2 - 1⟧` to
`⟦0, n - 1⟧²`.
-/
open prod decidable function
namespace nat
/-- Pairing function for the natural numbers. -/
@[pp_nodot] def mkpair (a b : ℕ) : ℕ :=
if a < b then b*b + a else a*a + a + b
/-- Unpairing function for the natural numbers. -/
@[pp_nodot] def unpair (n : ℕ) : ℕ × ℕ :=
let s := sqrt n in
if n - s*s < s then (n - s*s, s) else (s, n - s*s - s)
@[simp] theorem mkpair_unpair (n : ℕ) : mkpair (unpair n).1 (unpair n).2 = n :=
begin
dsimp only [unpair], set s := sqrt n,
have sm : s * s + (n - s * s) = n := add_sub_cancel_of_le (sqrt_le _),
split_ifs,
{ simp [mkpair, h, sm] },
{ have hl : n - s*s - s ≤ s :=
sub_le_iff_left.mpr (sub_le_iff_left.mpr $
by rw ← add_assoc; apply sqrt_le_add),
simp [mkpair, hl.not_lt, add_assoc, add_sub_cancel_of_le (le_of_not_gt h), sm] }
end
theorem mkpair_unpair' {n a b} (H : unpair n = (a, b)) : mkpair a b = n :=
by simpa [H] using mkpair_unpair n
@[simp] theorem unpair_mkpair (a b : ℕ) : unpair (mkpair a b) = (a, b) :=
begin
dunfold mkpair, split_ifs,
{ show unpair (b * b + a) = (a, b),
have be : sqrt (b * b + a) = b,
from sqrt_add_eq _ (le_trans (le_of_lt h) (nat.le_add_left _ _)),
simp [unpair, be, nat.add_sub_cancel, h] },
{ show unpair (a * a + a + b) = (a, b),
have ae : sqrt (a * a + (a + b)) = a,
{ rw sqrt_add_eq, exact add_le_add_left (le_of_not_gt h) _ },
simp [unpair, ae, nat.not_lt_zero, add_assoc] }
end
lemma surjective_unpair : surjective unpair :=
λ ⟨m, n⟩, ⟨mkpair m n, unpair_mkpair m n⟩
theorem unpair_lt {n : ℕ} (n1 : 1 ≤ n) : (unpair n).1 < n :=
let s := sqrt n in begin
simp [unpair], change sqrt n with s,
by_cases h : n - s * s < s; simp [h],
{ exact lt_of_lt_of_le h (sqrt_le_self _) },
{ simp at h,
have s0 : 0 < s := sqrt_pos.2 n1,
exact lt_of_le_of_lt h (sub_lt_self' n1 (mul_pos s0 s0)) }
end
@[simp] lemma unpair_zero : unpair 0 = 0 :=
by { rw unpair, simp }
theorem unpair_left_le : ∀ (n : ℕ), (unpair n).1 ≤ n
| 0 := by simp
| (n+1) := le_of_lt (unpair_lt (nat.succ_pos _))
theorem left_le_mkpair (a b : ℕ) : a ≤ mkpair a b :=
by simpa using unpair_left_le (mkpair a b)
theorem right_le_mkpair (a b : ℕ) : b ≤ mkpair a b :=
begin
by_cases h : a < b; simp [mkpair, h],
exact le_trans (le_mul_self _) (nat.le_add_right _ _)
end
theorem unpair_right_le (n : ℕ) : (unpair n).2 ≤ n :=
by simpa using right_le_mkpair n.unpair.1 n.unpair.2
theorem mkpair_lt_mkpair_left {a₁ a₂} (b) (h : a₁ < a₂) : mkpair a₁ b < mkpair a₂ b :=
begin
by_cases h₁ : a₁ < b; simp [mkpair, h₁, add_assoc],
{ by_cases h₂ : a₂ < b; simp [mkpair, h₂, h],
simp at h₂,
apply add_lt_add_of_le_of_lt,
exact mul_self_le_mul_self h₂,
exact lt_add_right _ _ _ h },
{ simp at h₁,
simp [not_lt_of_gt (lt_of_le_of_lt h₁ h)],
apply add_lt_add,
exact mul_self_lt_mul_self h,
apply add_lt_add_right; assumption }
end
theorem mkpair_lt_mkpair_right (a) {b₁ b₂} (h : b₁ < b₂) : mkpair a b₁ < mkpair a b₂ :=
begin
by_cases h₁ : a < b₁; simp [mkpair, h₁, add_assoc],
{ simp [mkpair, lt_trans h₁ h, h],
exact mul_self_lt_mul_self h },
{ by_cases h₂ : a < b₂; simp [mkpair, h₂, h],
simp at h₁,
rw [add_comm, add_comm _ a, add_assoc, add_lt_add_iff_left],
rwa [add_comm, ← sqrt_lt, sqrt_add_eq],
exact le_trans h₁ (nat.le_add_left _ _) }
end
end nat
open nat
section complete_lattice
lemma supr_unpair {α} [complete_lattice α] (f : ℕ → ℕ → α) :
(⨆ n : ℕ, f n.unpair.1 n.unpair.2) = ⨆ i j : ℕ, f i j :=
by rw [← (supr_prod : (⨆ i : ℕ × ℕ, f i.1 i.2) = _), ← nat.surjective_unpair.supr_comp]
lemma infi_unpair {α} [complete_lattice α] (f : ℕ → ℕ → α) :
(⨅ n : ℕ, f n.unpair.1 n.unpair.2) = ⨅ i j : ℕ, f i j :=
supr_unpair (show ℕ → ℕ → order_dual α, from f)
end complete_lattice
namespace set
lemma Union_unpair_prod {α β} {s : ℕ → set α} {t : ℕ → set β} :
(⋃ n : ℕ, (s n.unpair.fst).prod (t n.unpair.snd)) = (⋃ n, s n).prod (⋃ n, t n) :=
by { rw [← Union_prod], convert surjective_unpair.Union_comp _, refl }
lemma Union_unpair {α} (f : ℕ → ℕ → set α) :
(⋃ n : ℕ, f n.unpair.1 n.unpair.2) = ⋃ i j : ℕ, f i j :=
supr_unpair f
lemma Inter_unpair {α} (f : ℕ → ℕ → set α) :
(⋂ n : ℕ, f n.unpair.1 n.unpair.2) = ⋂ i j : ℕ, f i j :=
infi_unpair f
end set
|
da8e4b8753b01864d1a0f1c530310ccb6cefe78c | 08bd4ba4ca87dba1f09d2c96a26f5d65da81f4b4 | /src/Lean/Compiler/Specialize.lean | 1313be9dfbd864cf545168244c1a5795b27e8e7b | [
"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",
"Apache-2.0",
"LicenseRef-scancode-other-permissive",
"SunPro",
"CMU-Mach"... | permissive | gebner/lean4 | d51c4922640a52a6f7426536ea669ef18a1d9af5 | 8cd9ce06843c9d42d6d6dc43d3e81e3b49dfc20f | refs/heads/master | 1,685,732,780,391 | 1,672,962,627,000 | 1,673,459,398,000 | 373,307,283 | 0 | 0 | Apache-2.0 | 1,691,316,730,000 | 1,622,669,271,000 | Lean | UTF-8 | Lean | false | false | 5,074 | 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.Meta.Basic
import Lean.Attributes
namespace Lean.Compiler
inductive SpecializeAttributeKind where
| specialize | nospecialize
deriving Inhabited, BEq
builtin_initialize nospecializeAttr : TagAttribute ←
registerTagAttribute `nospecialize "mark definition to never be specialized"
private def elabSpecArgs (declName : Name) (args : Array Syntax) : MetaM (Array Nat) := do
if args.isEmpty then return #[]
let info ← getConstInfo declName
Meta.forallTelescopeReducing info.type fun xs _ => do
let argNames ← xs.mapM fun x => x.fvarId!.getUserName
let mut result := #[]
for arg in args do
if let some idx := arg.isNatLit? then
if idx == 0 then throwErrorAt arg "invalid specialization argument index, index must be greater than 0"
let idx := idx - 1
if idx >= argNames.size then
throwErrorAt arg "invalid argument index, `{declName}` has #{argNames.size} arguments"
if result.contains idx then throwErrorAt arg "invalid specialization argument index, `{argNames[idx]!}` has already been specified as a specialization candidate"
result := result.push idx
else
let argName := arg.getId
if let some idx := argNames.getIdx? argName then
if result.contains idx then throwErrorAt arg "invalid specialization argument name `{argName}`, it has already been specified as a specialization candidate"
result := result.push idx
else
throwErrorAt arg "invalid specialization argument name `{argName}`, `{declName}` does have an argument with this name"
return result.qsort (·<·)
builtin_initialize specializeAttr : ParametricAttribute (Array Nat) ←
registerParametricAttribute {
name := `specialize
descr := "mark definition to always be specialized"
getParam := fun declName stx => do
let args := stx[1].getArgs
elabSpecArgs declName args |>.run'
}
def getSpecializationArgs? (env : Environment) (declName : Name) : Option (Array Nat) :=
specializeAttr.getParam? env declName
def hasSpecializeAttribute (env : Environment) (declName : Name) : Bool :=
getSpecializationArgs? env declName |>.isSome
def hasNospecializeAttribute (env : Environment) (declName : Name) : Bool :=
nospecializeAttr.hasTag env declName
/- TODO: the rest of the file is for the old / current code generator. We should remove it as soon as we move to the new one. -/
@[export lean_has_specialize_attribute]
partial def hasSpecializeAttributeOld (env : Environment) (n : Name) : Bool :=
match specializeAttr.getParam? env n with
| some _ => true
| none => if n.isInternal then hasSpecializeAttributeOld env n.getPrefix else false -- TODO: remove recursion after we move to new compiler
@[export lean_has_nospecialize_attribute]
partial def hasNospecializeAttributeOld (env : Environment) (n : Name) : Bool :=
nospecializeAttr.hasTag env n ||
(n.isInternal && hasNospecializeAttributeOld env n.getPrefix) -- TODO: remove recursion after we move to new compiler
inductive SpecArgKind where
| fixed
| fixedNeutral -- computationally neutral
| fixedHO -- higher order
| fixedInst -- type class instance
| other
deriving Inhabited
structure SpecInfo where
mutualDecls : List Name
argKinds : SpecArgKind
deriving Inhabited
structure SpecState where
specInfo : SMap Name SpecInfo := {}
cache : SMap Expr Name := {}
deriving Inhabited
inductive SpecEntry where
| info (name : Name) (info : SpecInfo)
| cache (key : Expr) (fn : Name)
deriving Inhabited
namespace SpecState
def addEntry (s : SpecState) (e : SpecEntry) : SpecState :=
match e with
| SpecEntry.info name info => { s with specInfo := s.specInfo.insert name info }
| SpecEntry.cache key fn => { s with cache := s.cache.insert key fn }
def switch : SpecState → SpecState
| ⟨m₁, m₂⟩ => ⟨m₁.switch, m₂.switch⟩
end SpecState
builtin_initialize specExtension : SimplePersistentEnvExtension SpecEntry SpecState ←
registerSimplePersistentEnvExtension {
addEntryFn := SpecState.addEntry,
addImportedFn := fun es => (mkStateFromImportedEntries SpecState.addEntry {} es).switch
}
@[export lean_add_specialization_info]
def addSpecializationInfo (env : Environment) (fn : Name) (info : SpecInfo) : Environment :=
specExtension.addEntry env (SpecEntry.info fn info)
@[export lean_get_specialization_info]
def getSpecializationInfo (env : Environment) (fn : Name) : Option SpecInfo :=
(specExtension.getState env).specInfo.find? fn
@[export lean_cache_specialization]
def cacheSpecialization (env : Environment) (e : Expr) (fn : Name) : Environment :=
specExtension.addEntry env (SpecEntry.cache e fn)
@[export lean_get_cached_specialization]
def getCachedSpecialization (env : Environment) (e : Expr) : Option Name :=
(specExtension.getState env).cache.find? e
end Lean.Compiler
|
87bfefbb5e602abef564d73d7f4e9ce2cf89dfef | d7b899533a520b46d705c8f4eaab26bb8571c153 | /subst.lean | 30b06a414135953a3f94a12e65d4e05c74dabeec | [
"MIT"
] | permissive | fgdorais/old_birkhoff | d043467859476eb412cc612f4daa9933dd031090 | c528743f6ebe65633cee5e9fef83a5794d2350c6 | refs/heads/master | 1,631,920,649,967 | 1,530,902,154,000 | 1,530,902,154,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 3,534 | lean | -- birkhoff/subst.lean --
-- Copyright Ⓒ 2015 François G. Dorais. All rights reserved.
-- Relesed under the MIT License as described in the file LICENSE.
import data .basic .algebras
open nat
definition subst [sig : SIG] (m n : nat) : Type := fin m → term n
definition const.alg [instance] [sig : SIG] : ALG const :=
ALG.mk const.appl
definition const.hom [instance] [sig : SIG] (A : Type) [alg : ALG A] : HOM (const.value A) :=
HOM.mk (λ i cs, rfl)
definition term.alg [instance] [sig : SIG] (n : nat) : ALG (term n) :=
ALG.mk term.appl
namespace subst
variable [sig : SIG]
include sig
definition apply {m n : nat} :
subst m n → term m → term n :=
take us t, @term.value sig (term n) (term.alg n) m t us
lemma apply_proj {m n : nat} {us : subst m n} (i : fin m) :
subst.apply us (term.proj i) = us i :=
!term.value_proj
lemma apply_func {m n : nat} {us : subst m n} (i : sig) {ts : fin (func.arity i) → term m} :
subst.apply us (term.appl i ts) = term.appl i (λ k, subst.apply us (ts k)) :=
!term.value_appl
definition hom [instance]
{m n : nat} (us : subst m n) : HOM (subst.apply us) :=
HOM.mk (take i ts, subst.apply_func i)
definition single {n : nat} (i : fin n) (t : term n) : subst n n :=
λ j : fin n, decidable.rec_on (fin.has_decidable_eq n i j)
(take Heq, t)
(take Hne, term.proj j)
definition comp {m n p : nat} : subst n p → subst m n → subst m p :=
take us vs k, subst.apply us (vs k)
theorem comp_apply {m n p : nat} {us : subst n p} {vs : subst m n} {t : term m} :
subst.apply (comp us vs) t = subst.apply us (subst.apply vs t) :=
@hom.term sig _ (term.alg n) _ (term.alg p) _ (subst.hom us) _ t vs
theorem comp_assoc {m n p q : nat} {us : subst p q} {vs : subst n p} {ws : subst m n} :
comp us (comp vs ws) = comp (comp us vs) ws :=
funext (take k, calc
comp us (comp vs ws) k
= subst.apply us (comp vs ws k) : rfl
... = subst.apply us (subst.apply vs (ws k)) : rfl
... = subst.apply (comp us vs) (ws k) : comp_apply
... = comp (comp us vs) ws k : rfl)
definition id {n : nat} : subst n n :=
λ k : fin n, term.proj k
theorem id_apply {n : nat} {t : term n} : subst.apply id t = t :=
term.induction_on t
(take n i, apply_proj i)
(take n i ts IH,
have IH' : (λ k, subst.apply id (ts k)) = ts,
from funext IH,
calc
subst.apply id (term.appl i ts)
= term.appl i (λ k, subst.apply id (ts k)) : apply_func
... = term.appl i ts : IH')
theorem comp_id_left {m n : nat} {us : subst m n} :
comp id us = us :=
funext (take k, id_apply)
theorem comp_id_right {m n : nat} {us : subst m n} :
comp us id = us :=
funext (take k, apply_proj k)
definition map {m n : nat} (f : fin m → fin n) : subst m n :=
λ k : fin m, term.proj (f k)
theorem map_id {n : nat} : map (λ k : fin n, k) = id := rfl
theorem map_comp {m n p : nat} (f : fin n → fin p) (g : fin m → fin n) :
comp (map f) (map g) = map (λ k, f (g k)) :=
let h := λ k, f (g k) in
funext (take k, calc
comp (map f) (map g) k
= subst.apply (map f) (map g k) : rfl
... = subst.apply (map f) (term.proj (g k)) : rfl
... = (map f) (g k) : apply_proj
... = term.proj (h k) : rfl
... = map h k : rfl)
end subst
|
db32ba1fe89321048dde6daee5e1cd957cc0d4e7 | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /tests/compiler/strictOrSimp.lean | ea135c5015366725dae7cc4f7711f330be7d0a4d | [
"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 | 211 | lean | partial def spin : Nat → Bool
| n => spin (n)
@[inline] def C : Nat := 0
def f (b : Nat) :=
if strictOr (C == 0) (spin b) then "hello"
else "world"
def main (xs : List String) : IO Unit :=
IO.println (f 0)
|
88031106bab891dc73092960d91f0d69eeef9cf8 | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/group_theory/monoid_localization.lean | d27767d83379980d89760fce2d56cb4d3674c04f | [
"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 | 54,963 | lean | /-
Copyright (c) 2019 Amelia Livingston. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Amelia Livingston
-/
import group_theory.congruence
import group_theory.submonoid
import algebra.group.units
import algebra.punit_instances
/-!
# Localizations of commutative monoids
Localizing a commutative ring at one of its submonoids does not rely on the ring's addition, so
we can generalize localizations to commutative monoids.
We characterize the localization of a commutative monoid `M` at a submonoid `S` up to
isomorphism; that is, a commutative monoid `N` is the localization of `M` at `S` iff we can find a
monoid homomorphism `f : M →* N` satisfying 3 properties:
1. For all `y ∈ S`, `f y` is a unit;
2. For all `z : N`, there exists `(x, y) : M × S` such that `z * f y = f x`;
3. For all `x, y : M`, `f x = f y` iff there exists `c ∈ S` such that `x * c = y * c`.
Given such a localization map `f : M →* N`, we can define the surjection
`localization_map.mk'` sending `(x, y) : M × S` to `f x * (f y)⁻¹`, and
`localization_map.lift`, the homomorphism from `N` induced by a homomorphism from `M` which maps
elements of `S` to invertible elements of the codomain. Similarly, given commutative monoids
`P, Q`, a submonoid `T` of `P` and a localization map for `T` from `P` to `Q`, then a homomorphism
`g : M →* P` such that `g(S) ⊆ T` induces a homomorphism of localizations,
`localization_map.map`, from `N` to `Q`.
We treat the special case of localizing away from an element in the sections `away_map` and `away`.
We also define the quotient of `M × S` by the unique congruence relation (equivalence relation
preserving a binary operation) `r` such that for any other congruence relation `s` on `M × S`
satisfying '`∀ y ∈ S`, `(1, 1) ∼ (y, y)` under `s`', we have that `(x₁, y₁) ∼ (x₂, y₂)` by `s`
whenever `(x₁, y₁) ∼ (x₂, y₂)` by `r`. We show this relation is equivalent to the standard
localization relation.
This defines the localization as a quotient type, `localization`, but the majority of
subsequent lemmas in the file are given in terms of localizations up to isomorphism, using maps
which satisfy the characteristic predicate.
## 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.
The infimum form of the localization congruence relation is chosen as 'canonical' here, since it
shortens some proofs.
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_monoid_of_mk'` and associated
lemmas. These show the quotient map `mk : M → S → localization S` equals the
surjection `localization_map.mk'` induced by the map
`monoid_of : localization_map S (localization S)` (where `of` establishes the
localization as a quotient type satisfies the characteristic predicate). The lemma
`mk_eq_monoid_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.
## Tags
localization, monoid localization, quotient monoid, congruence relation, characteristic predicate,
commutative monoid
-/
set_option old_structure_cmd true
namespace add_submonoid
variables {M : Type*} [add_comm_monoid M] (S : add_submonoid M) (N : Type*) [add_comm_monoid N]
/-- The type of add_monoid homomorphisms satisfying the characteristic predicate: if `f : M →+ N`
satisfies this predicate, then `N` is isomorphic to the localization of `M` at `S`. -/
@[nolint has_inhabited_instance] structure localization_map
extends add_monoid_hom M N :=
(map_add_units' : ∀ y : S, is_add_unit (to_fun y))
(surj' : ∀ z : N, ∃ x : M × S, z + to_fun x.2 = to_fun x.1)
(eq_iff_exists' : ∀ x y, to_fun x = to_fun y ↔ ∃ c : S, x + c = y + c)
/-- The add_monoid hom underlying a `localization_map` of `add_comm_monoid`s. -/
add_decl_doc localization_map.to_add_monoid_hom
end add_submonoid
variables {M : Type*} [comm_monoid M] (S : submonoid M) (N : Type*) [comm_monoid N]
{P : Type*} [comm_monoid P]
namespace submonoid
/-- The type of monoid homomorphisms satisfying the characteristic predicate: if `f : M →* N`
satisfies this predicate, then `N` is isomorphic to the localization of `M` at `S`. -/
@[nolint has_inhabited_instance] structure localization_map
extends monoid_hom M N :=
(map_units' : ∀ y : S, is_unit (to_fun y))
(surj' : ∀ z : N, ∃ x : M × S, z * to_fun x.2 = to_fun x.1)
(eq_iff_exists' : ∀ x y, to_fun x = to_fun y ↔ ∃ c : S, x * c = y * c)
attribute [to_additive add_submonoid.localization_map] submonoid.localization_map
attribute [to_additive add_submonoid.localization_map.to_add_monoid_hom]
submonoid.localization_map.to_monoid_hom
/-- The monoid hom underlying a `localization_map`. -/
add_decl_doc localization_map.to_monoid_hom
end submonoid
namespace localization
run_cmd to_additive.map_namespace `localization `add_localization
/-- The congruence relation on `M × S`, `M` a `comm_monoid` and `S` a submonoid of `M`, whose
quotient is the localization of `M` at `S`, defined as the unique congruence relation on
`M × S` such that for any other congruence relation `s` on `M × S` where for all `y ∈ S`,
`(1, 1) ∼ (y, y)` under `s`, we have that `(x₁, y₁) ∼ (x₂, y₂)` by `r` implies
`(x₁, y₁) ∼ (x₂, y₂)` by `s`. -/
@[to_additive "The congruence relation on `M × S`, `M` an `add_comm_monoid` and `S`
an `add_submonoid` of `M`, whose quotient is the localization of `M` at `S`, defined as the unique
congruence relation on `M × S` such that for any other congruence relation `s` on `M × S` where
for all `y ∈ S`, `(0, 0) ∼ (y, y)` under `s`, we have that `(x₁, y₁) ∼ (x₂, y₂)` by `r` implies
`(x₁, y₁) ∼ (x₂, y₂)` by `s`."]
def r (S : submonoid M) : con (M × S) :=
Inf {c | ∀ y : S, c 1 (y, y)}
/-- An alternate form of the congruence relation on `M × S`, `M` a `comm_monoid` and `S` a
submonoid of `M`, whose quotient is the localization of `M` at `S`. -/
@[to_additive "An alternate form of the congruence relation on `M × S`, `M` a `comm_monoid` and
`S` a submonoid of `M`, whose quotient is the localization of `M` at `S`."]
def r' : con (M × S) :=
begin
refine { r := λ a b : M × S, ∃ c : S, a.1 * b.2 * c = b.1 * a.2 * c,
iseqv := ⟨λ a, ⟨1, rfl⟩, λ a b ⟨c, hc⟩, ⟨c, hc.symm⟩, _⟩,
.. },
{ rintros a b c ⟨t₁, ht₁⟩ ⟨t₂, ht₂⟩,
use b.2 * t₁ * t₂,
simp only [submonoid.coe_mul],
calc a.1 * c.2 * (b.2 * t₁ * t₂) = a.1 * b.2 * t₁ * c.2 * t₂ : by ac_refl
... = b.1 * c.2 * t₂ * a.2 * t₁ : by { rw ht₁, ac_refl }
... = c.1 * a.2 * (b.2 * t₁ * t₂) : by { rw ht₂, ac_refl } },
{ rintros a b c d ⟨t₁, ht₁⟩ ⟨t₂, ht₂⟩,
use t₁ * t₂,
calc (a.1 * c.1) * (b.2 * d.2) * (t₁ * t₂) = (a.1 * b.2 * t₁) * (c.1 * d.2 * t₂) :
by ac_refl
... = (b.1 * d.1) * (a.2 * c.2) * (t₁ * t₂) : by { rw [ht₁, ht₂], ac_refl } }
end
/-- The congruence relation used to localize a `comm_monoid` at a submonoid can be expressed
equivalently as an infimum (see `localization.r`) or explicitly
(see `localization.r'`). -/
@[to_additive "The additive congruence relation used to localize an `add_comm_monoid` at a
submonoid can be expressed equivalently as an infimum (see `add_localization.r`) or
explicitly (see `add_localization.r'`)."]
theorem r_eq_r' : r S = r' S :=
le_antisymm (Inf_le $ λ _, ⟨1, by simp⟩) $
le_Inf $ λ b H ⟨p, q⟩ y ⟨t, ht⟩,
begin
rw [← mul_one (p, q), ← mul_one y],
refine b.trans (b.mul (b.refl _) (H (y.2 * t))) _,
convert b.symm (b.mul (b.refl y) (H (q * t))) using 1,
rw [prod.mk_mul_mk, submonoid.coe_mul, ← mul_assoc, ht, mul_left_comm, mul_assoc],
refl
end
variables {S}
@[to_additive]
lemma r_iff_exists {x y : M × S} : r S x y ↔ ∃ c : S, x.1 * y.2 * c = y.1 * x.2 * c :=
by rw r_eq_r' S; refl
end localization
/-- The localization of a `comm_monoid` at one of its submonoids (as a quotient type). -/
@[to_additive add_localization "The localization of an `add_comm_monoid` at one
of its submonoids (as a quotient type)."]
def localization := (localization.r S).quotient
namespace localization
@[to_additive] instance inhabited :
inhabited (localization S) :=
con.quotient.inhabited
@[to_additive] instance : comm_monoid (localization S) :=
(r S).comm_monoid
variables {S}
/-- Given a `comm_monoid` `M` and submonoid `S`, `mk` sends `x : M`, `y ∈ S` to the equivalence
class of `(x, y)` in the localization of `M` at `S`. -/
@[to_additive "Given an `add_comm_monoid` `M` and submonoid `S`, `mk` sends `x : M`, `y ∈ S` to
the equivalence class of `(x, y)` in the localization of `M` at `S`."]
def mk (x : M) (y : S) : localization S := (r S).mk' (x, y)
@[elab_as_eliminator, to_additive]
theorem ind {p : localization S → Prop}
(H : ∀ (y : M × S), p (mk y.1 y.2)) (x) : p x :=
by rcases x; convert H x; exact prod.mk.eta.symm
@[elab_as_eliminator, to_additive]
theorem induction_on {p : localization S → Prop} (x)
(H : ∀ (y : M × S), p (mk y.1 y.2)) : p x := ind H x
@[elab_as_eliminator, to_additive]
theorem induction_on₂ {p : localization S → localization S → Prop} (x y)
(H : ∀ (x y : M × S), p (mk x.1 x.2) (mk y.1 y.2)) : p x y :=
induction_on x $ λ x, induction_on y $ H x
@[elab_as_eliminator, to_additive]
theorem induction_on₃
{p : localization S → localization S → localization S → Prop} (x y z)
(H : ∀ (x y z : M × S), p (mk x.1 x.2) (mk y.1 y.2) (mk z.1 z.2)) : p x y z :=
induction_on₂ x y $ λ x y, induction_on z $ H x y
@[to_additive] lemma one_rel (y : S) : r S 1 (y, y) := λ b hb, hb y
@[to_additive] theorem r_of_eq {x y : M × S} (h : y.1 * x.2 = x.1 * y.2) : r S x y :=
r_iff_exists.2 ⟨1, by rw h⟩
end localization
variables {S N}
namespace monoid_hom
/-- Makes a localization map from a `comm_monoid` hom satisfying the characteristic predicate. -/
@[to_additive "Makes a localization map from an `add_comm_monoid` hom satisfying the characteristic
predicate."]
def to_localization_map (f : M →* N) (H1 : ∀ y : S, is_unit (f y))
(H2 : ∀ z, ∃ x : M × S, z * f x.2 = f x.1) (H3 : ∀ x y, f x = f y ↔ ∃ c : S, x * c = y * c) :
submonoid.localization_map S N :=
{ map_units' := H1,
surj' := H2,
eq_iff_exists' := H3,
.. f }
end monoid_hom
namespace submonoid
namespace localization_map
/-- Short for `to_monoid_hom`; used to apply a localization map as a function. -/
@[to_additive "Short for `to_add_monoid_hom`; used to apply a localization map as a function."]
abbreviation to_map (f : localization_map S N) := f.to_monoid_hom
@[to_additive, ext] lemma ext {f g : localization_map S N} (h : ∀ x, f.to_map x = g.to_map x) :
f = g :=
by cases f; cases g; simp only; exact funext h
attribute [ext] add_submonoid.localization_map.ext
@[to_additive] lemma ext_iff {f g : localization_map S N} :
f = g ↔ ∀ x, f.to_map x = g.to_map x :=
⟨λ h x, h ▸ rfl, ext⟩
@[to_additive] lemma to_map_injective :
function.injective (@localization_map.to_map _ _ S N _) :=
λ _ _ h, ext $ monoid_hom.ext_iff.1 h
@[to_additive] lemma map_units (f : localization_map S N) (y : S) :
is_unit (f.to_map y) := f.4 y
@[to_additive] lemma surj (f : localization_map S N) (z : N) :
∃ x : M × S, z * f.to_map x.2 = f.to_map x.1 := f.5 z
@[to_additive] lemma eq_iff_exists (f : localization_map S N) {x y} :
f.to_map x = f.to_map y ↔ ∃ c : S, x * c = y * c := f.6 x y
/-- Given a localization map `f : M →* N`, a section function sending `z : N` to some
`(x, y) : M × S` such that `f x * (f y)⁻¹ = z`. -/
@[to_additive "Given a localization map `f : M →+ N`, a section function sending `z : N`
to some `(x, y) : M × S` such that `f x - f y = z`."]
noncomputable def sec (f : localization_map S N) (z : N) : M × S :=
classical.some $ f.surj z
@[to_additive] lemma sec_spec {f : localization_map S N} (z : N) :
z * f.to_map (f.sec z).2 = f.to_map (f.sec z).1 :=
classical.some_spec $ f.surj z
@[to_additive] lemma sec_spec' {f : localization_map S N} (z : N) :
f.to_map (f.sec z).1 = f.to_map (f.sec z).2 * z :=
by rw [mul_comm, sec_spec]
/-- Given a monoid hom `f : M →* N` and submonoid `S ⊆ M` such that `f(S) ⊆ units N`, for all
`w : M, z : N` and `y ∈ S`, we have `w * (f y)⁻¹ = z ↔ w = f y * z`. -/
@[to_additive "Given an add_monoid hom `f : M →+ N` and submonoid `S ⊆ M` such that
`f(S) ⊆ add_units N`, for all `w : M, z : N` and `y ∈ S`, we have `w - f y = z ↔ w = f y + z`."]
lemma mul_inv_left {f : M →* N} (h : ∀ y : S, is_unit (f y))
(y : S) (w z) : w * ↑(is_unit.lift_right (f.mrestrict S) h y)⁻¹ = z ↔ w = f y * z :=
by rw mul_comm; convert units.inv_mul_eq_iff_eq_mul _;
exact (is_unit.coe_lift_right (f.mrestrict S) h _).symm
/-- Given a monoid hom `f : M →* N` and submonoid `S ⊆ M` such that `f(S) ⊆ units N`, for all
`w : M, z : N` and `y ∈ S`, we have `z = w * (f y)⁻¹ ↔ z * f y = w`. -/
@[to_additive "Given an add_monoid hom `f : M →+ N` and submonoid `S ⊆ M` such that
`f(S) ⊆ add_units N`, for all `w : M, z : N` and `y ∈ S`, we have `z = w - f y ↔ z + f y = w`."]
lemma mul_inv_right {f : M →* N} (h : ∀ y : S, is_unit (f y))
(y : S) (w z) : z = w * ↑(is_unit.lift_right (f.mrestrict S) h y)⁻¹ ↔ z * f y = w :=
by rw [eq_comm, mul_inv_left h, mul_comm, eq_comm]
/-- Given a monoid hom `f : M →* N` and submonoid `S ⊆ M` such that
`f(S) ⊆ units N`, for all `x₁ x₂ : M` and `y₁, y₂ ∈ S`, we have
`f x₁ * (f y₁)⁻¹ = f x₂ * (f y₂)⁻¹ ↔ f (x₁ * y₂) = f (x₂ * y₁)`. -/
@[simp, to_additive "Given an add_monoid hom `f : M →+ N` and submonoid `S ⊆ M` such that
`f(S) ⊆ add_units N`, for all `x₁ x₂ : M` and `y₁, y₂ ∈ S`, we have
`f x₁ - f y₁ = f x₂ - f y₂ ↔ f (x₁ + y₂) = f (x₂ + y₁)`."]
lemma mul_inv {f : M →* N} (h : ∀ y : S, is_unit (f y)) {x₁ x₂} {y₁ y₂ : S} :
f x₁ * ↑(is_unit.lift_right (f.mrestrict S) h y₁)⁻¹ =
f x₂ * ↑(is_unit.lift_right (f.mrestrict S) h y₂)⁻¹ ↔ f (x₁ * y₂) = f (x₂ * y₁) :=
by rw [mul_inv_right h, mul_assoc, mul_comm _ (f y₂), ←mul_assoc, mul_inv_left h, mul_comm x₂,
f.map_mul, f.map_mul]
/-- Given a monoid hom `f : M →* N` and submonoid `S ⊆ M` such that `f(S) ⊆ units N`, for all
`y, z ∈ S`, we have `(f y)⁻¹ = (f z)⁻¹ → f y = f z`. -/
@[to_additive "Given an add_monoid hom `f : M →+ N` and submonoid `S ⊆ M` such that
`f(S) ⊆ add_units N`, for all `y, z ∈ S`, we have `- (f y) = - (f z) → f y = f z`."]
lemma inv_inj {f : M →* N} (hf : ∀ y : S, is_unit (f y)) {y z}
(h : (is_unit.lift_right (f.mrestrict S) hf y)⁻¹ = (is_unit.lift_right (f.mrestrict S) hf z)⁻¹) :
f y = f z :=
by rw [←mul_one (f y), eq_comm, ←mul_inv_left hf y (f z) 1, h];
convert units.inv_mul _; exact (is_unit.coe_lift_right (f.mrestrict S) hf _).symm
/-- Given a monoid hom `f : M →* N` and submonoid `S ⊆ M` such that `f(S) ⊆ units N`, for all
`y ∈ S`, `(f y)⁻¹` is unique. -/
@[to_additive "Given an add_monoid hom `f : M →+ N` and submonoid `S ⊆ M` such that
`f(S) ⊆ add_units N`, for all `y ∈ S`, `- (f y)` is unique."]
lemma inv_unique {f : M →* N} (h : ∀ y : S, is_unit (f y)) {y : S}
{z} (H : f y * z = 1) : ↑(is_unit.lift_right (f.mrestrict S) h y)⁻¹ = z :=
by rw [←one_mul ↑(_)⁻¹, mul_inv_left, ←H]
variables (f : localization_map S N)
@[to_additive] lemma map_right_cancel {x y} {c : S} (h : f.to_map (c * x) = f.to_map (c * y)) :
f.to_map x = f.to_map y :=
begin
rw [f.to_map.map_mul, f.to_map.map_mul] at h,
cases f.map_units c with u hu,
rw ←hu at h,
exact (units.mul_right_inj u).1 h,
end
@[to_additive] lemma map_left_cancel {x y} {c : S} (h : f.to_map (x * c) = f.to_map (y * c)) :
f.to_map x = f.to_map y :=
f.map_right_cancel $ by rw [mul_comm _ x, mul_comm _ y, h]
/-- Given a localization map `f : M →* N`, the surjection sending `(x, y) : M × S` to
`f x * (f y)⁻¹`. -/
@[to_additive "Given a localization map `f : M →+ N`, the surjection sending `(x, y) : M × S`
to `f x - f y`."]
noncomputable def mk' (f : localization_map S N) (x : M) (y : S) : N :=
f.to_map x * ↑(is_unit.lift_right (f.to_map.mrestrict S) f.map_units y)⁻¹
@[to_additive] lemma mk'_mul (x₁ x₂ : M) (y₁ y₂ : S) :
f.mk' (x₁ * x₂) (y₁ * y₂) = f.mk' x₁ y₁ * f.mk' x₂ y₂ :=
(mul_inv_left f.map_units _ _ _).2 $
show _ = _ * (_ * _ * (_ * _)), by
rw [←mul_assoc, ←mul_assoc, mul_inv_right f.map_units, mul_assoc, mul_assoc,
mul_comm _ (f.to_map x₂), ←mul_assoc, ←mul_assoc, mul_inv_right f.map_units,
submonoid.coe_mul, f.to_map.map_mul, f.to_map.map_mul];
ac_refl
@[to_additive] lemma mk'_one (x) : f.mk' x (1 : S) = f.to_map x :=
by rw [mk', monoid_hom.map_one]; exact mul_one _
/-- Given a localization map `f : M →* N` for a submonoid `S ⊆ M`, for all `z : N` we have that if
`x : M, y ∈ S` are such that `z * f y = f x`, then `f x * (f y)⁻¹ = z`. -/
@[simp, to_additive "Given a localization map `f : M →+ N` for a submonoid `S ⊆ M`, for all `z : N`
we have that if `x : M, y ∈ S` are such that `z + f y = f x`, then `f x - f y = z`."]
lemma mk'_sec (z : N) : f.mk' (f.sec z).1 (f.sec z).2 = z :=
show _ * _ = _, by rw [←sec_spec, mul_inv_left, mul_comm]
@[to_additive] lemma mk'_surjective (z : N) : ∃ x (y : S), f.mk' x y = z :=
⟨(f.sec z).1, (f.sec z).2, f.mk'_sec z⟩
@[to_additive] lemma mk'_spec (x) (y : S) :
f.mk' x y * f.to_map y = f.to_map x :=
show _ * _ * _ = _, by rw [mul_assoc, mul_comm _ (f.to_map y), ←mul_assoc, mul_inv_left, mul_comm]
@[to_additive] lemma mk'_spec' (x) (y : S) :
f.to_map y * f.mk' x y = f.to_map x :=
by rw [mul_comm, mk'_spec]
@[to_additive] theorem eq_mk'_iff_mul_eq {x} {y : S} {z} :
z = f.mk' x y ↔ z * f.to_map y = f.to_map x :=
⟨λ H, by rw [H, mk'_spec], λ H, by erw [mul_inv_right, H]; refl⟩
@[to_additive] theorem mk'_eq_iff_eq_mul {x} {y : S} {z} :
f.mk' x y = z ↔ f.to_map x = z * f.to_map y :=
by rw [eq_comm, eq_mk'_iff_mul_eq, eq_comm]
@[to_additive] lemma mk'_eq_iff_eq {x₁ x₂} {y₁ y₂ : S} :
f.mk' x₁ y₁ = f.mk' x₂ y₂ ↔ f.to_map (x₁ * y₂) = f.to_map (x₂ * y₁) :=
⟨λ H, by rw [f.to_map.map_mul, f.mk'_eq_iff_eq_mul.1 H, mul_assoc,
mul_comm (f.to_map _), ←mul_assoc, mk'_spec, f.to_map.map_mul],
λ H, by rw [mk'_eq_iff_eq_mul, mk', mul_assoc, mul_comm _ (f.to_map y₁), ←mul_assoc,
←f.to_map.map_mul, ←H, f.to_map.map_mul, mul_inv_right f.map_units]⟩
@[to_additive] protected lemma eq {a₁ b₁} {a₂ b₂ : S} :
f.mk' a₁ a₂ = f.mk' b₁ b₂ ↔ ∃ c : S, a₁ * b₂ * c = b₁ * a₂ * c :=
f.mk'_eq_iff_eq.trans $ f.eq_iff_exists
@[to_additive] protected lemma eq' {a₁ b₁} {a₂ b₂ : S} :
f.mk' a₁ a₂ = f.mk' b₁ b₂ ↔ localization.r S (a₁, a₂) (b₁, b₂) :=
by rw [f.eq, localization.r_iff_exists]
@[to_additive] lemma eq_iff_eq (g : localization_map S P) {x y} :
f.to_map x = f.to_map y ↔ g.to_map x = g.to_map y :=
f.eq_iff_exists.trans g.eq_iff_exists.symm
@[to_additive] lemma mk'_eq_iff_mk'_eq (g : localization_map S P) {x₁ x₂}
{y₁ y₂ : S} : f.mk' x₁ y₁ = f.mk' x₂ y₂ ↔ g.mk' x₁ y₁ = g.mk' x₂ y₂ :=
f.eq'.trans g.eq'.symm
/-- Given a localization map `f : M →* N` for a submonoid `S ⊆ M`, for all `x₁ : M` and `y₁ ∈ S`,
if `x₂ : M, y₂ ∈ S` are such that `f x₁ * (f y₁)⁻¹ * f y₂ = f x₂`, then there exists `c ∈ S`
such that `x₁ * y₂ * c = x₂ * y₁ * c`. -/
@[to_additive "Given a localization map `f : M →+ N` for a submonoid `S ⊆ M`, for all `x₁ : M`
and `y₁ ∈ S`, if `x₂ : M, y₂ ∈ S` are such that `(f x₁ - f y₁) + f y₂ = f x₂`, then there exists
`c ∈ S` such that `x₁ + y₂ + c = x₂ + y₁ + c`."]
lemma exists_of_sec_mk' (x) (y : S) :
∃ c : S, x * (f.sec $ f.mk' x y).2 * c = (f.sec $ f.mk' x y).1 * y * c :=
f.eq_iff_exists.1 $ f.mk'_eq_iff_eq.1 $ (mk'_sec _ _).symm
@[to_additive] lemma mk'_eq_of_eq {a₁ b₁ : M} {a₂ b₂ : S} (H : b₁ * a₂ = a₁ * b₂) :
f.mk' a₁ a₂ = f.mk' b₁ b₂ :=
f.mk'_eq_iff_eq.2 $ H ▸ rfl
@[simp, to_additive] lemma mk'_self' (y : S) :
f.mk' (y : M) y = 1 :=
show _ * _ = _, by rw [mul_inv_left, mul_one]
@[simp, to_additive] lemma mk'_self (x) (H : x ∈ S) :
f.mk' x ⟨x, H⟩ = 1 :=
by convert mk'_self' _ _; refl
@[to_additive] lemma mul_mk'_eq_mk'_of_mul (x₁ x₂) (y : S) :
f.to_map x₁ * f.mk' x₂ y = f.mk' (x₁ * x₂) y :=
by rw [←mk'_one, ←mk'_mul, one_mul]
@[to_additive] lemma mk'_mul_eq_mk'_of_mul (x₁ x₂) (y : S) :
f.mk' x₂ y * f.to_map x₁ = f.mk' (x₁ * x₂) y :=
by rw [mul_comm, mul_mk'_eq_mk'_of_mul]
@[to_additive] lemma mul_mk'_one_eq_mk' (x) (y : S) :
f.to_map x * f.mk' 1 y = f.mk' x y :=
by rw [mul_mk'_eq_mk'_of_mul, mul_one]
@[simp, to_additive] lemma mk'_mul_cancel_right (x : M) (y : S) :
f.mk' (x * y) y = f.to_map x :=
by rw [←mul_mk'_one_eq_mk', f.to_map.map_mul, mul_assoc, mul_mk'_one_eq_mk', mk'_self', mul_one]
@[to_additive] lemma mk'_mul_cancel_left (x) (y : S) :
f.mk' ((y : M) * x) y = f.to_map x :=
by rw [mul_comm, mk'_mul_cancel_right]
@[to_additive] lemma is_unit_comp (j : N →* P) (y : S) :
is_unit (j.comp f.to_map y) :=
⟨units.map j $ is_unit.lift_right (f.to_map.mrestrict S) f.map_units y,
show j _ = j _, from congr_arg j $
(is_unit.coe_lift_right (f.to_map.mrestrict S) f.map_units _)⟩
variables {g : M →* P}
/-- Given a localization map `f : M →* N` for a submonoid `S ⊆ M` and a map of `comm_monoid`s
`g : M →* P` such that `g(S) ⊆ units P`, `f x = f y → g x = g y` for all `x y : M`. -/
@[to_additive "Given a localization map `f : M →+ N` for a submonoid `S ⊆ M` and a map
of `add_comm_monoid`s `g : M →+ P` such that `g(S) ⊆ add_units P`, `f x = f y → g x = g y`
for all `x y : M`."]
lemma eq_of_eq (hg : ∀ y : S, is_unit (g y)) {x y} (h : f.to_map x = f.to_map y) :
g x = g y :=
begin
obtain ⟨c, hc⟩ := f.eq_iff_exists.1 h,
rw [←mul_one (g x), ←is_unit.mul_lift_right_inv (g.mrestrict S) hg c],
show _ * (g c * _) = _,
rw [←mul_assoc, ←g.map_mul, hc, mul_inv_left hg, g.map_mul, mul_comm],
end
/-- Given `comm_monoid`s `M, P`, localization maps `f : M →* N, k : P →* Q` for submonoids
`S, T` respectively, and `g : M →* P` such that `g(S) ⊆ T`, `f x = f y` implies
`k (g x) = k (g y)`. -/
@[to_additive "Given `add_comm_monoid`s `M, P`, localization maps `f : M →+ N, k : P →+ Q` for
submonoids `S, T` respectively, and `g : M →+ P` such that `g(S) ⊆ T`, `f x = f y`
implies `k (g x) = k (g y)`."]
lemma comp_eq_of_eq {T : submonoid P} {Q : Type*} [comm_monoid Q]
(hg : ∀ y : S, g y ∈ T) (k : localization_map T Q)
{x y} (h : f.to_map x = f.to_map y) : k.to_map (g x) = k.to_map (g y) :=
f.eq_of_eq (λ y : S, show is_unit (k.to_map.comp g y), from k.map_units ⟨g y, hg y⟩) h
variables (hg : ∀ y : S, is_unit (g y))
/-- Given a localization map `f : M →* N` for a submonoid `S ⊆ M` and a map of `comm_monoid`s
`g : M →* P` such that `g y` is invertible for all `y : S`, the homomorphism induced from
`N` to `P` sending `z : N` to `g x * (g y)⁻¹`, where `(x, y) : M × S` are such that
`z = f x * (f y)⁻¹`. -/
@[to_additive "Given a localization map `f : M →+ N` for a submonoid `S ⊆ M` and a map
of `add_comm_monoid`s `g : M →+ P` such that `g y` is invertible for all `y : S`, the homomorphism
induced from `N` to `P` sending `z : N` to `g x - g y`, where `(x, y) : M × S` are such that
`z = f x - f y`."]
noncomputable def lift : N →* P :=
{ to_fun := λ z, g (f.sec z).1 * ↑(is_unit.lift_right (g.mrestrict S) hg (f.sec z).2)⁻¹,
map_one' := by rw [mul_inv_left, mul_one]; exact f.eq_of_eq hg
(by rw [←sec_spec, one_mul]),
map_mul' := λ x y,
begin
rw [mul_inv_left hg, ←mul_assoc, ←mul_assoc, mul_inv_right hg,
mul_comm _ (g (f.sec y).1), ←mul_assoc, ←mul_assoc, mul_inv_right hg],
repeat { rw ←g.map_mul },
exact f.eq_of_eq hg (by repeat { rw f.to_map.map_mul <|> rw sec_spec' }; ac_refl)
end }
variables {S g}
/-- Given a localization map `f : M →* N` for a submonoid `S ⊆ M` and a map of `comm_monoid`s
`g : M →* P` such that `g y` is invertible for all `y : S`, the homomorphism induced from
`N` to `P` maps `f x * (f y)⁻¹` to `g x * (g y)⁻¹` for all `x : M, y ∈ S`. -/
@[to_additive "Given a localization map `f : M →+ N` for a submonoid `S ⊆ M` and a map
of `add_comm_monoid`s `g : M →+ P` such that `g y` is invertible for all `y : S`, the homomorphism
induced from `N` to `P` maps `f x - f y` to `g x - g y` for all `x : M, y ∈ S`."]
lemma lift_mk' (x y) :
f.lift hg (f.mk' x y) = g x * ↑(is_unit.lift_right (g.mrestrict S) hg y)⁻¹ :=
(mul_inv hg).2 $ f.eq_of_eq hg $ by
rw [f.to_map.map_mul, f.to_map.map_mul, sec_spec', mul_assoc, f.mk'_spec, mul_comm]
/-- Given a localization map `f : M →* N` for a submonoid `S ⊆ M`, if a `comm_monoid` map
`g : M →* P` induces a map `f.lift hg : N →* P` then for all `z : N, v : P`, we have
`f.lift hg z = v ↔ g x = g y * v`, where `x : M, y ∈ S` are such that `z * f y = f x`. -/
@[to_additive "Given a localization map `f : M →+ N` for a submonoid `S ⊆ M`, if
an `add_comm_monoid` map `g : M →+ P` induces a map `f.lift hg : N →+ P` then for all
`z : N, v : P`, we have `f.lift hg z = v ↔ g x = g y + v`, where `x : M, y ∈ S` are such that
`z + f y = f x`."]
lemma lift_spec (z v) :
f.lift hg z = v ↔ g (f.sec z).1 = g (f.sec z).2 * v :=
mul_inv_left hg _ _ v
/-- Given a localization map `f : M →* N` for a submonoid `S ⊆ M`, if a `comm_monoid` map
`g : M →* P` induces a map `f.lift hg : N →* P` then for all `z : N, v w : P`, we have
`f.lift hg z * w = v ↔ g x * w = g y * v`, where `x : M, y ∈ S` are such that
`z * f y = f x`. -/
@[to_additive "Given a localization map `f : M →+ N` for a submonoid `S ⊆ M`, if
an `add_comm_monoid` map `g : M →+ P` induces a map `f.lift hg : N →+ P` then for all
`z : N, v w : P`, we have `f.lift hg z + w = v ↔ g x + w = g y + v`, where `x : M, y ∈ S` are such
that `z + f y = f x`."]
lemma lift_spec_mul (z w v) :
f.lift hg z * w = v ↔ g (f.sec z).1 * w = g (f.sec z).2 * v :=
begin
rw mul_comm,
show _ * (_ * _) = _ ↔ _,
rw [←mul_assoc, mul_inv_left hg, mul_comm],
end
@[to_additive] lemma lift_mk'_spec (x v) (y : S) :
f.lift hg (f.mk' x y) = v ↔ g x = g y * v :=
by rw f.lift_mk' hg; exact mul_inv_left hg _ _ _
/-- Given a localization map `f : M →* N` for a submonoid `S ⊆ M`, if a `comm_monoid` map
`g : M →* P` induces a map `f.lift hg : N →* P` then for all `z : N`, we have
`f.lift hg z * g y = g x`, where `x : M, y ∈ S` are such that `z * f y = f x`. -/
@[to_additive "Given a localization map `f : M →+ N` for a submonoid `S ⊆ M`, if
an `add_comm_monoid` map `g : M →+ P` induces a map `f.lift hg : N →+ P` then for all `z : N`, we
have `f.lift hg z + g y = g x`, where `x : M, y ∈ S` are such that `z + f y = f x`."]
lemma lift_mul_right (z) :
f.lift hg z * g (f.sec z).2 = g (f.sec z).1 :=
show _ * _ * _ = _, by erw [mul_assoc, is_unit.lift_right_inv_mul, mul_one]
/-- Given a localization map `f : M →* N` for a submonoid `S ⊆ M`, if a `comm_monoid` map
`g : M →* P` induces a map `f.lift hg : N →* P` then for all `z : N`, we have
`g y * f.lift hg z = g x`, where `x : M, y ∈ S` are such that `z * f y = f x`. -/
@[to_additive "Given a localization map `f : M →+ N` for a submonoid `S ⊆ M`, if
an `add_comm_monoid` map `g : M →+ P` induces a map `f.lift hg : N →+ P` then for all `z : N`, we
have `g y + f.lift hg z = g x`, where `x : M, y ∈ S` are such that `z + f y = f x`."]
lemma lift_mul_left (z) :
g (f.sec z).2 * f.lift hg z = g (f.sec z).1 :=
by rw [mul_comm, lift_mul_right]
@[simp, to_additive] lemma lift_eq (x : M) :
f.lift hg (f.to_map x) = g x :=
by rw [lift_spec, ←g.map_mul]; exact f.eq_of_eq hg (by rw [sec_spec', f.to_map.map_mul])
@[to_additive] lemma lift_eq_iff {x y : M × S} :
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) :=
by rw [lift_mk', lift_mk', mul_inv hg]
@[simp, to_additive] lemma lift_comp : (f.lift hg).comp f.to_map = g :=
by ext; exact f.lift_eq hg _
@[simp, to_additive] lemma lift_of_comp (j : N →* P) :
f.lift (f.is_unit_comp j) = j :=
begin
ext,
rw lift_spec,
show j _ = j _ * _,
erw [←j.map_mul, sec_spec'],
end
@[to_additive] lemma epic_of_localization_map {j k : N →* P}
(h : ∀ a, j.comp f.to_map a = k.comp f.to_map a) : j = k :=
begin
rw [←f.lift_of_comp j, ←f.lift_of_comp k],
congr' 1 with x, exact h x,
end
@[to_additive] lemma lift_unique {j : N →* P}
(hj : ∀ x, j (f.to_map x) = g x) : f.lift hg = j :=
begin
ext,
rw [lift_spec, ←hj, ←hj, ←j.map_mul],
apply congr_arg,
rw ←sec_spec',
end
@[simp, to_additive] lemma lift_id (x) : f.lift f.map_units x = x :=
monoid_hom.ext_iff.1 (f.lift_of_comp $ monoid_hom.id N) x
/-- Given two localization maps `f : M →* N, k : M →* P` for a submonoid `S ⊆ M`,
the hom from `P` to `N` induced by `f` is left inverse to the hom from `N` to `P`
induced by `k`. -/
@[simp, to_additive] lemma lift_left_inverse {k : localization_map S P} (z : N) :
k.lift f.map_units (f.lift k.map_units z) = z :=
begin
rw lift_spec,
cases f.surj z with x hx,
conv_rhs {congr, skip, rw f.eq_mk'_iff_mul_eq.2 hx},
rw [mk', ←mul_assoc, mul_inv_right f.map_units, ←f.to_map.map_mul, ←f.to_map.map_mul],
apply k.eq_of_eq f.map_units,
rw [k.to_map.map_mul, k.to_map.map_mul, ←sec_spec, mul_assoc, lift_spec_mul],
repeat { rw ←k.to_map.map_mul },
apply f.eq_of_eq k.map_units,
repeat { rw f.to_map.map_mul },
rw [sec_spec', ←hx],
ac_refl,
end
@[to_additive] lemma lift_surjective_iff :
function.surjective (f.lift hg) ↔ ∀ v : P, ∃ x : M × S, v * g x.2 = g x.1 :=
begin
split,
{ intros H v,
obtain ⟨z, hz⟩ := H v,
obtain ⟨x, hx⟩ := f.surj z,
use x,
rw [←hz, f.eq_mk'_iff_mul_eq.2 hx, lift_mk', mul_assoc, mul_comm _ (g ↑x.2)],
erw [is_unit.mul_lift_right_inv (g.mrestrict S) hg, mul_one] },
{ intros H v,
obtain ⟨x, hx⟩ := H v,
use f.mk' x.1 x.2,
rw [lift_mk', mul_inv_left hg, mul_comm, ←hx] }
end
@[to_additive] lemma lift_injective_iff :
function.injective (f.lift hg) ↔ ∀ x y, f.to_map x = f.to_map y ↔ g x = g y :=
begin
split,
{ intros H x y,
split,
{ exact f.eq_of_eq hg },
{ intro h,
rw [←f.lift_eq hg, ←f.lift_eq hg] at h,
exact H h }},
{ intros H z w h,
obtain ⟨x, hx⟩ := f.surj z,
obtain ⟨y, hy⟩ := f.surj w,
rw [←f.mk'_sec z, ←f.mk'_sec w],
exact (mul_inv f.map_units).2 ((H _ _).2 $ (mul_inv hg).1 h) }
end
variables {T : submonoid P} (hy : ∀ y : S, g y ∈ T) {Q : Type*} [comm_monoid Q]
(k : localization_map T Q)
/-- Given a `comm_monoid` homomorphism `g : M →* P` where for submonoids `S ⊆ M, T ⊆ P` we have
`g(S) ⊆ T`, the induced monoid homomorphism from the localization of `M` at `S` to the
localization of `P` at `T`: if `f : M →* N` and `k : P →* Q` are localization maps for `S` and
`T` respectively, we send `z : N` to `k (g x) * (k (g y))⁻¹`, where `(x, y) : M × S` are such
that `z = f x * (f y)⁻¹`. -/
@[to_additive "Given a `add_comm_monoid` homomorphism `g : M →+ P` where for submonoids
`S ⊆ M, T ⊆ P` we have `g(S) ⊆ T`, the induced add_monoid homomorphism from the localization of `M`
at `S` to the localization of `P` at `T`: if `f : M →+ N` and `k : P →+ Q` are localization maps
for `S` and `T` respectively, we send `z : N` to `k (g x) - k (g y)`, where `(x, y) : M × S` are
such that `z = f x - f y`."]
noncomputable def map : N →* Q :=
@lift _ _ _ _ _ _ _ f (k.to_map.comp g) $ λ y, k.map_units ⟨g y, hy y⟩
variables {k}
@[to_additive] 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, to_additive] 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⟩
@[to_additive] lemma map_mk' (x) (y : S) :
f.map hy k (f.mk' x y) = k.mk' (g x) ⟨g y, hy y⟩ :=
begin
rw [map, lift_mk', mul_inv_left],
{ show k.to_map (g x) = k.to_map (g y) * _,
rw mul_mk'_eq_mk'_of_mul,
exact (k.mk'_mul_cancel_left (g x) ⟨(g y), hy y⟩).symm },
end
/-- Given localization maps `f : M →* N, k : P →* Q` for submonoids `S, T` respectively, if a
`comm_monoid` homomorphism `g : M →* P` induces a `f.map hy k : N →* Q`, then for all `z : N`,
`u : Q`, we have `f.map hy k z = u ↔ k (g x) = k (g y) * u` where `x : M, y ∈ S` are such that
`z * f y = f x`. -/
@[to_additive "Given localization maps `f : M →+ N, k : P →+ Q` for submonoids `S, T` respectively,
if an `add_comm_monoid` homomorphism `g : M →+ P` induces a `f.map hy k : N →+ Q`, then for all
`z : N`, `u : Q`, we have `f.map hy k z = u ↔ k (g x) = k (g y) + u` where `x : M, y ∈ S` are such
that `z + f y = f x`."]
lemma map_spec (z u) :
f.map hy k z = u ↔ k.to_map (g (f.sec z).1) = k.to_map (g (f.sec z).2) * u :=
f.lift_spec (λ y, k.map_units ⟨g y, hy y⟩) _ _
/-- Given localization maps `f : M →* N, k : P →* Q` for submonoids `S, T` respectively, if a
`comm_monoid` homomorphism `g : M →* P` induces a `f.map hy k : N →* Q`, then for all `z : N`,
we have `f.map hy k z * k (g y) = k (g x)` where `x : M, y ∈ S` are such that
`z * f y = f x`. -/
@[to_additive "Given localization maps `f : M →+ N, k : P →+ Q` for submonoids `S, T` respectively,
if an `add_comm_monoid` homomorphism `g : M →+ P` induces a `f.map hy k : N →+ Q`, then
for all `z : N`, we have `f.map hy k z + k (g y) = k (g x)` where `x : M, y ∈ S` are such that
`z + f y = f x`."]
lemma map_mul_right (z) :
f.map hy k z * (k.to_map (g (f.sec z).2)) = k.to_map (g (f.sec z).1) :=
f.lift_mul_right (λ y, k.map_units ⟨g y, hy y⟩) _
/-- Given localization maps `f : M →* N, k : P →* Q` for submonoids `S, T` respectively, if a
`comm_monoid` homomorphism `g : M →* P` induces a `f.map hy k : N →* Q`, then for all `z : N`,
we have `k (g y) * f.map hy k z = k (g x)` where `x : M, y ∈ S` are such that
`z * f y = f x`. -/
@[to_additive "Given localization maps `f : M →+ N, k : P →+ Q` for submonoids `S, T` respectively,
if an `add_comm_monoid` homomorphism `g : M →+ P` induces a `f.map hy k : N →+ Q`, then for all
`z : N`, we have `k (g y) + f.map hy k z = k (g x)` where `x : M, y ∈ S` are such that
`z + f y = f x`."]
lemma map_mul_left (z) :
k.to_map (g (f.sec z).2) * f.map hy k z = k.to_map (g (f.sec z).1) :=
by rw [mul_comm, f.map_mul_right]
@[simp, to_additive] lemma map_id (z : N) :
f.map (λ y, show monoid_hom.id M y ∈ S, from y.2) f z = z :=
f.lift_id z
/-- If `comm_monoid` homs `g : M →* P, l : P →* A` induce maps of localizations, the composition
of the induced maps equals the map of localizations induced by `l ∘ g`. -/
@[to_additive "If `add_comm_monoid` homs `g : M →+ 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_monoid A] {U : submonoid A} {R} [comm_monoid R]
(j : localization_map U R) {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 :=
begin
ext z,
show j.to_map _ * _ = j.to_map (l _) * _,
{ rw [mul_inv_left, ←mul_assoc, mul_inv_right],
show j.to_map _ * j.to_map (l (g _)) = j.to_map (l _) * _,
rw [←j.to_map.map_mul, ←j.to_map.map_mul, ←l.map_mul, ←l.map_mul],
exact k.comp_eq_of_eq hl j
(by rw [k.to_map.map_mul, k.to_map.map_mul, sec_spec', mul_assoc, map_mul_right]) },
end
/-- If `comm_monoid` homs `g : M →* P, l : P →* A` induce maps of localizations, the composition
of the induced maps equals the map of localizations induced by `l ∘ g`. -/
@[to_additive "If `add_comm_monoid` homs `g : M →+ 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_monoid A] {U : submonoid A} {R} [comm_monoid R]
(j : localization_map U R) {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
section away_map
variables (x : M)
/-- Given `x : M`, the type of `comm_monoid` homomorphisms `f : M →* N` such that `N`
is isomorphic to the localization of `M` at the submonoid generated by `x`. -/
@[reducible, to_additive "Given `x : M`, the type of `add_comm_monoid` homomorphisms `f : M →+ N`
such that `N` is isomorphic to the localization of `M` at the submonoid generated by `x`."]
def away_map (N' : Type*) [comm_monoid N'] :=
localization_map (powers x) N'
variables (F : away_map x N)
/-- Given `x : M` and a localization map `F : M →* N` away from `x`, `inv_self` is `(F x)⁻¹`. -/
noncomputable def away_map.inv_self : N :=
F.mk' 1 ⟨x, mem_powers _⟩
/-- Given `x : M`, a localization map `F : M →* N` away from `x`, and a map of `comm_monoid`s
`g : M →* P` such that `g x` is invertible, the homomorphism induced from `N` to `P` sending
`z : N` to `g y * (g x)⁻ⁿ`, where `y : M, n : ℕ` are such that `z = F y * (F x)⁻ⁿ`. -/
noncomputable def away_map.lift (hg : is_unit (g x)) : N →* P :=
F.lift $ λ y, show is_unit (g y.1),
begin
obtain ⟨n, hn⟩ := y.2,
rw [←hn, g.map_pow],
exact is_unit.map (monoid_hom.of $ ((^ n) : P → P)) hg,
end
@[simp] lemma away_map.lift_eq (hg : is_unit (g x)) (a : M) :
F.lift x hg (F.to_map a) = g a := lift_eq _ _ _
@[simp] lemma away_map.lift_comp (hg : is_unit (g x)) :
(F.lift x hg).comp F.to_map = g := lift_comp _ _
/-- Given `x y : M` and localization maps `F : M →* N, G : M →* P` away from `x` and `x * y`
respectively, the homomorphism induced from `N` to `P`. -/
noncomputable def away_to_away_right (y : M) (G : away_map (x * y) P) : N →* P :=
F.lift x $ show is_unit (G.to_map x), from
is_unit_of_mul_eq_one (G.to_map x) (G.mk' y ⟨x * y, mem_powers _⟩) $
by rw [mul_mk'_eq_mk'_of_mul, mk'_self]
end away_map
end localization_map
end submonoid
namespace add_submonoid
namespace localization_map
section away_map
variables {A : Type*} [add_comm_monoid A] (x : A) {B : Type*}
[add_comm_monoid B] (F : away_map x B) {C : Type*} [add_comm_monoid C] {g : A →+ C}
/-- Given `x : A` and a localization map `F : A →+ B` away from `x`, `neg_self` is `- (F x)`. -/
noncomputable def away_map.neg_self : B :=
F.mk' 0 ⟨x, mem_multiples _⟩
/-- Given `x : A`, a localization map `F : A →+ B` away from `x`, and a map of `add_comm_monoid`s
`g : A →+ C` such that `g x` is invertible, the homomorphism induced from `B` to `C` sending
`z : B` to `g y - n • g x`, where `y : A, n : ℕ` are such that `z = F y - n • F x`. -/
noncomputable def away_map.lift (hg : is_add_unit (g x)) : B →+ C :=
F.lift $ λ y, show is_add_unit (g y.1),
begin
obtain ⟨n, hn⟩ := y.2,
rw ← hn,
dsimp,
rw [g.map_nsmul],
convert is_add_unit.map (add_monoid_hom.of $ (λ x, n • x)) hg,
end
@[simp] lemma away_map.lift_eq (hg : is_add_unit (g x)) (a : A) :
F.lift x hg (F.to_map a) = g a := lift_eq _ _ _
@[simp] lemma away_map.lift_comp (hg : is_add_unit (g x)) :
(F.lift x hg).comp F.to_map = g := lift_comp _ _
/-- Given `x y : A` and localization maps `F : A →+ B, G : A →+ C` away from `x` and `x + y`
respectively, the homomorphism induced from `B` to `C`. -/
noncomputable def away_to_away_right (y : A) (G : away_map (x + y) C) : B →+ C :=
F.lift x $ show is_add_unit (G.to_map x), from
is_add_unit_of_add_eq_zero (G.to_map x) (G.mk' y ⟨x + y, mem_multiples _⟩) $
by rw [add_mk'_eq_mk'_of_add, mk'_self]
end away_map
end localization_map
end add_submonoid
namespace submonoid
namespace localization_map
variables (f : S.localization_map N) {g : M →* P} (hg : ∀ (y : S), is_unit (g y))
{T : submonoid P} {Q : Type*} [comm_monoid Q]
/-- If `f : M →* N` and `k : M →* P` are localization maps for a submonoid `S`, we get an
isomorphism of `N` and `P`. -/
@[to_additive "If `f : M →+ N` and `k : M →+ R` are localization maps for a submonoid `S`,
we get an isomorphism of `N` and `R`."]
noncomputable def mul_equiv_of_localizations
(k : localization_map S P) : N ≃* P :=
⟨f.lift k.map_units, k.lift f.map_units, f.lift_left_inverse,
k.lift_left_inverse, monoid_hom.map_mul _⟩
@[simp, to_additive] lemma mul_equiv_of_localizations_apply
{k : localization_map S P} {x} :
f.mul_equiv_of_localizations k x = f.lift k.map_units x := rfl
@[simp, to_additive] lemma mul_equiv_of_localizations_symm_apply
{k : localization_map S P} {x} :
(f.mul_equiv_of_localizations k).symm x = k.lift f.map_units x := rfl
@[to_additive] lemma mul_equiv_of_localizations_symm_eq_mul_equiv_of_localizations
{k : localization_map S P} :
(k.mul_equiv_of_localizations f).symm = f.mul_equiv_of_localizations k := rfl
/-- If `f : M →* N` is a localization map for a submonoid `S` and `k : N ≃* P` is an isomorphism
of `comm_monoid`s, `k ∘ f` is a localization map for `M` at `S`. -/
@[to_additive "If `f : M →+ N` is a localization map for a submonoid `S` and `k : N ≃+ P` is an
isomorphism of `add_comm_monoid`s, `k ∘ f` is a localization map for `M` at `S`."]
def of_mul_equiv_of_localizations (k : N ≃* P) : localization_map S P :=
(k.to_monoid_hom.comp f.to_map).to_localization_map (λ y, is_unit_comp f k.to_monoid_hom y)
(λ v, let ⟨z, hz⟩ := k.to_equiv.surjective v in
let ⟨x, hx⟩ := f.surj z in ⟨x, show v * k _ = k _, by rw [←hx, k.map_mul, ←hz]; refl⟩)
(λ x y, k.apply_eq_iff_eq.trans f.eq_iff_exists)
@[simp, to_additive] lemma of_mul_equiv_of_localizations_apply {k : N ≃* P} (x) :
(f.of_mul_equiv_of_localizations k).to_map x = k (f.to_map x) := rfl
@[to_additive] lemma of_mul_equiv_of_localizations_eq {k : N ≃* P} :
(f.of_mul_equiv_of_localizations k).to_map = k.to_monoid_hom.comp f.to_map := rfl
@[to_additive] lemma symm_comp_of_mul_equiv_of_localizations_apply {k : N ≃* P} (x) :
k.symm ((f.of_mul_equiv_of_localizations k).to_map x) = f.to_map x :=
k.symm_apply_apply (f.to_map x)
@[to_additive] lemma symm_comp_of_mul_equiv_of_localizations_apply' {k : P ≃* N} (x) :
k ((f.of_mul_equiv_of_localizations k.symm).to_map x) = f.to_map x :=
k.apply_symm_apply (f.to_map x)
@[to_additive] lemma of_mul_equiv_of_localizations_eq_iff_eq {k : N ≃* P} {x y} :
(f.of_mul_equiv_of_localizations k).to_map x = y ↔ f.to_map x = k.symm y :=
k.to_equiv.eq_symm_apply.symm
@[to_additive add_equiv_of_localizations_right_inv]
lemma mul_equiv_of_localizations_right_inv (k : localization_map S P) :
f.of_mul_equiv_of_localizations (f.mul_equiv_of_localizations k) = k :=
to_map_injective $ f.lift_comp k.map_units
@[to_additive add_equiv_of_localizations_right_inv_apply, simp]
lemma mul_equiv_of_localizations_right_inv_apply
{k : localization_map S P} {x} :
(f.of_mul_equiv_of_localizations (f.mul_equiv_of_localizations k)).to_map x = k.to_map x :=
ext_iff.1 (f.mul_equiv_of_localizations_right_inv k) x
@[to_additive] lemma mul_equiv_of_localizations_left_inv (k : N ≃* P) :
f.mul_equiv_of_localizations (f.of_mul_equiv_of_localizations k) = k :=
mul_equiv.ext $ monoid_hom.ext_iff.1 $ f.lift_of_comp k.to_monoid_hom
@[simp, to_additive] lemma mul_equiv_of_localizations_left_inv_apply {k : N ≃* P} (x) :
f.mul_equiv_of_localizations (f.of_mul_equiv_of_localizations k) x = k x :=
by rw mul_equiv_of_localizations_left_inv
@[simp, to_additive] lemma of_mul_equiv_of_localizations_id :
f.of_mul_equiv_of_localizations (mul_equiv.refl N) = f :=
by ext; refl
@[to_additive] lemma of_mul_equiv_of_localizations_comp {k : N ≃* P} {j : P ≃* Q} :
(f.of_mul_equiv_of_localizations (k.trans j)).to_map =
j.to_monoid_hom.comp (f.of_mul_equiv_of_localizations k).to_map :=
by ext; refl
/-- Given `comm_monoid`s `M, P` and submonoids `S ⊆ M, T ⊆ P`, if `f : M →* N` is a localization
map for `S` and `k : P ≃* M` is an isomorphism of `comm_monoid`s such that `k(T) = S`, `f ∘ k`
is a localization map for `T`. -/
@[to_additive "Given `comm_monoid`s `M, P` and submonoids `S ⊆ M, T ⊆ P`, if `f : M →* N` is
a localization map for `S` and `k : P ≃* M` is an isomorphism of `comm_monoid`s such that
`k(T) = S`, `f ∘ k` is a localization map for `T`."]
def of_mul_equiv_of_dom {k : P ≃* M} (H : T.map k.to_monoid_hom = S) :
localization_map T N :=
let H' : S.comap k.to_monoid_hom = T :=
H ▸ (set_like.coe_injective $ T.1.preimage_image_eq k.to_equiv.injective) in
(f.to_map.comp k.to_monoid_hom).to_localization_map
(λ y, let ⟨z, hz⟩ := f.map_units ⟨k y, H ▸ set.mem_image_of_mem k y.2⟩ in ⟨z, hz⟩)
(λ z, let ⟨x, hx⟩ := f.surj z in let ⟨v, hv⟩ := k.to_equiv.surjective x.1 in
let ⟨w, hw⟩ := k.to_equiv.surjective x.2 in ⟨(v, ⟨w, H' ▸ show k w ∈ S, from hw.symm ▸ x.2.2⟩),
show z * f.to_map (k.to_equiv w) = f.to_map (k.to_equiv v), by erw [hv, hw, hx]; refl⟩)
(λ x y, show f.to_map _ = f.to_map _ ↔ _, by erw f.eq_iff_exists;
exact ⟨λ ⟨c, hc⟩, let ⟨d, hd⟩ := k.to_equiv.surjective c in
⟨⟨d, H' ▸ show k d ∈ S, from hd.symm ▸ c.2⟩, by erw [←hd, ←k.map_mul, ←k.map_mul] at hc;
exact k.to_equiv.injective hc⟩, λ ⟨c, hc⟩, ⟨⟨k c, H ▸ set.mem_image_of_mem k c.2⟩,
by erw ←k.map_mul; rw [hc, k.map_mul]; refl⟩⟩)
@[simp, to_additive] lemma of_mul_equiv_of_dom_apply
{k : P ≃* M} (H : T.map k.to_monoid_hom = S) (x) :
(f.of_mul_equiv_of_dom H).to_map x = f.to_map (k x) := rfl
@[to_additive] lemma of_mul_equiv_of_dom_eq
{k : P ≃* M} (H : T.map k.to_monoid_hom = S) :
(f.of_mul_equiv_of_dom H).to_map = f.to_map.comp k.to_monoid_hom := rfl
@[to_additive] lemma of_mul_equiv_of_dom_comp_symm {k : P ≃* M}
(H : T.map k.to_monoid_hom = S) (x) :
(f.of_mul_equiv_of_dom H).to_map (k.symm x) = f.to_map x :=
congr_arg f.to_map $ k.apply_symm_apply x
@[to_additive] lemma of_mul_equiv_of_dom_comp {k : M ≃* P}
(H : T.map k.symm.to_monoid_hom = S) (x) :
(f.of_mul_equiv_of_dom H).to_map (k x) = f.to_map x :=
congr_arg f.to_map $ k.symm_apply_apply x
/-- A special case of `f ∘ id = f`, `f` a localization map. -/
@[simp, to_additive "A special case of `f ∘ id = f`, `f` a localization map."]
lemma of_mul_equiv_of_dom_id :
f.of_mul_equiv_of_dom (show S.map (mul_equiv.refl M).to_monoid_hom = S, from
submonoid.ext $ λ x, ⟨λ ⟨y, hy, h⟩, h ▸ hy, λ h, ⟨x, h, rfl⟩⟩) = f :=
by ext; refl
/-- Given localization maps `f : M →* N, k : P →* U` for submonoids `S, T` respectively, an
isomorphism `j : M ≃* P` such that `j(S) = T` induces an isomorphism of localizations
`N ≃* U`. -/
@[to_additive "Given localization maps `f : M →+ N, k : P →+ U` for submonoids `S, T` respectively,
an isomorphism `j : M ≃+ P` such that `j(S) = T` induces an isomorphism of
localizations `N ≃+ U`."]
noncomputable def mul_equiv_of_mul_equiv
(k : localization_map T Q) {j : M ≃* P} (H : S.map j.to_monoid_hom = T) :
N ≃* Q :=
f.mul_equiv_of_localizations $ k.of_mul_equiv_of_dom H
@[simp, to_additive] lemma mul_equiv_of_mul_equiv_eq_map_apply
{k : localization_map T Q} {j : M ≃* P} (H : S.map j.to_monoid_hom = T) (x) :
f.mul_equiv_of_mul_equiv k H x =
f.map (λ y : S, show j.to_monoid_hom y ∈ T, from H ▸ set.mem_image_of_mem j y.2) k x := rfl
@[to_additive] lemma mul_equiv_of_mul_equiv_eq_map
{k : localization_map T Q} {j : M ≃* P} (H : S.map j.to_monoid_hom = T) :
(f.mul_equiv_of_mul_equiv k H).to_monoid_hom =
f.map (λ y : S, show j.to_monoid_hom y ∈ T, from H ▸ set.mem_image_of_mem j y.2) k := rfl
@[simp, to_additive] lemma mul_equiv_of_mul_equiv_eq {k : localization_map T Q}
{j : M ≃* P} (H : S.map j.to_monoid_hom = T) (x) :
f.mul_equiv_of_mul_equiv k H (f.to_map x) = k.to_map (j x) :=
f.map_eq (λ y : S, H ▸ set.mem_image_of_mem j y.2) _
@[simp, to_additive] lemma mul_equiv_of_mul_equiv_mk' {k : localization_map T Q}
{j : M ≃* P} (H : S.map j.to_monoid_hom = T) (x y) :
f.mul_equiv_of_mul_equiv k H (f.mk' x y) = k.mk' (j x) ⟨j y, H ▸ set.mem_image_of_mem j y.2⟩ :=
f.map_mk' (λ y : S, H ▸ set.mem_image_of_mem j y.2) _ _
@[simp, to_additive] lemma of_mul_equiv_of_mul_equiv_apply
{k : localization_map T Q} {j : M ≃* P} (H : S.map j.to_monoid_hom = T) (x) :
(f.of_mul_equiv_of_localizations (f.mul_equiv_of_mul_equiv k H)).to_map x = k.to_map (j x) :=
ext_iff.1 (f.mul_equiv_of_localizations_right_inv (k.of_mul_equiv_of_dom H)) x
@[to_additive] lemma of_mul_equiv_of_mul_equiv
{k : localization_map T Q} {j : M ≃* P} (H : S.map j.to_monoid_hom = T) :
(f.of_mul_equiv_of_localizations (f.mul_equiv_of_mul_equiv k H)).to_map =
k.to_map.comp j.to_monoid_hom :=
monoid_hom.ext $ f.of_mul_equiv_of_mul_equiv_apply H
end localization_map
end submonoid
namespace localization
variables (S)
/-- Natural hom sending `x : M`, `M` a `comm_monoid`, to the equivalence class of
`(x, 1)` in the localization of `M` at a submonoid. -/
@[to_additive "Natural homomorphism sending `x : M`, `M` an `add_comm_monoid`, to the equivalence
class of `(x, 0)` in the localization of `M` at a submonoid."]
def monoid_of : submonoid.localization_map S (localization S) :=
{ map_units' := λ y, is_unit_iff_exists_inv.2 ⟨mk 1 y, (r S).eq.2 $
show r S (_, 1 * y) 1, by simpa using (r S).symm (one_rel y)⟩,
surj' := λ z, induction_on z $ λ x, ⟨x, (r S).eq.2 $
show r S (x.1 * x.2, x.2 * 1) (x.1, 1), by
rw [mul_comm x.2, ←mul_one (x.1, (1 : S))];
exact (r S).mul ((r S).refl (x.1, 1)) ((r S).symm $ one_rel x.2)⟩,
eq_iff_exists' := λ x y, (r S).eq.trans $ r_iff_exists.trans $
show (∃ (c : S), x * 1 * c = y * 1 * c) ↔ _, by rw [mul_one, mul_one],
..(r S).mk'.comp $ monoid_hom.inl M S }
variables {S}
@[to_additive] lemma mk_one_eq_monoid_of_mk (x) : mk x 1 = (monoid_of S).to_map x := rfl
@[to_additive] lemma mk_eq_monoid_of_mk'_apply (x y) : mk x y = (monoid_of S).mk' x y :=
show _ = _ * _, from (submonoid.localization_map.mul_inv_right (monoid_of S).map_units _ _ _).2 $
begin
rw [←mk_one_eq_monoid_of_mk, ←mk_one_eq_monoid_of_mk,
show mk x y * mk y 1 = mk (x * y) (1 * y), by rw mul_comm 1 y; refl,
show mk x 1 = mk (x * 1) ((1 : S) * 1), by rw [mul_one, mul_one]],
exact (con.eq _).2 (con.symm _ $ (localization.r S).mul
(con.refl _ (x, 1)) $ one_rel _),
end
@[simp, to_additive] lemma mk_eq_monoid_of_mk' : mk = (monoid_of S).mk' :=
funext $ λ _, funext $ λ _, mk_eq_monoid_of_mk'_apply _ _
variables (f : submonoid.localization_map S N)
/-- Given a localization map `f : M →* N` for a submonoid `S`, we get an isomorphism between
the localization of `M` at `S` as a quotient type and `N`. -/
@[to_additive "Given a localization map `f : M →+ N` for a submonoid `S`, we get an isomorphism
between the localization of `M` at `S` as a quotient type and `N`."]
noncomputable def mul_equiv_of_quotient (f : submonoid.localization_map S N) :
localization S ≃* N :=
(monoid_of S).mul_equiv_of_localizations f
variables {f}
@[simp, to_additive] lemma mul_equiv_of_quotient_apply (x) :
mul_equiv_of_quotient f x = (monoid_of S).lift f.map_units x := rfl
@[simp, to_additive] lemma mul_equiv_of_quotient_mk' (x y) :
mul_equiv_of_quotient f ((monoid_of S).mk' x y) = f.mk' x y :=
(monoid_of S).lift_mk' _ _ _
@[to_additive] lemma mul_equiv_of_quotient_mk (x y) :
mul_equiv_of_quotient f (mk x y) = f.mk' x y :=
by rw mk_eq_monoid_of_mk'_apply; exact mul_equiv_of_quotient_mk' _ _
@[simp, to_additive] lemma mul_equiv_of_quotient_monoid_of (x) :
mul_equiv_of_quotient f ((monoid_of S).to_map x) = f.to_map x :=
(monoid_of S).lift_eq _ _
@[simp, to_additive] lemma mul_equiv_of_quotient_symm_mk' (x y) :
(mul_equiv_of_quotient f).symm (f.mk' x y) = (monoid_of S).mk' x y :=
f.lift_mk' _ _ _
@[to_additive] lemma mul_equiv_of_quotient_symm_mk (x y) :
(mul_equiv_of_quotient f).symm (f.mk' x y) = mk x y :=
by rw mk_eq_monoid_of_mk'_apply; exact mul_equiv_of_quotient_symm_mk' _ _
@[simp, to_additive] lemma mul_equiv_of_quotient_symm_monoid_of (x) :
(mul_equiv_of_quotient f).symm (f.to_map x) = (monoid_of S).to_map x :=
f.lift_eq _ _
section away
variables (x : M)
/-- Given `x : M`, the localization of `M` at the submonoid generated by `x`, as a quotient. -/
@[reducible, to_additive "Given `x : M`, the localization of `M` at the submonoid generated
by `x`, as a quotient."]
def away := localization (submonoid.powers x)
/-- Given `x : M`, `inv_self` is `x⁻¹` in the localization (as a quotient type) of `M` at the
submonoid generated by `x`. -/
@[to_additive "Given `x : M`, `neg_self` is `-x` in the localization (as a quotient type) of `M`
at the submonoid generated by `x`."]
def away.inv_self : away x :=
mk 1 ⟨x, submonoid.mem_powers _⟩
/-- Given `x : M`, the natural hom sending `y : M`, `M` a `comm_monoid`, to the equivalence class
of `(y, 1)` in the localization of `M` at the submonoid generated by `x`. -/
@[reducible, to_additive "Given `x : M`, the natural hom sending `y : M`, `M` an `add_comm_monoid`,
to the equivalence class of `(y, 0)` in the localization of `M` at the submonoid
generated by `x`."]
def away.monoid_of : submonoid.localization_map.away_map x (away x) :=
monoid_of (submonoid.powers x)
@[simp, to_additive] lemma away.mk_eq_monoid_of_mk' : mk = (away.monoid_of x).mk' :=
mk_eq_monoid_of_mk'
/-- Given `x : M` and a localization map `f : M →* N` away from `x`, we get an isomorphism between
the localization of `M` at the submonoid generated by `x` as a quotient type and `N`. -/
@[to_additive "Given `x : M` and a localization map `f : M →+ N` away from `x`, we get an
isomorphism between the localization of `M` at the submonoid generated by `x` as a quotient type
and `N`."]
noncomputable def away.mul_equiv_of_quotient (f : submonoid.localization_map.away_map x N) :
away x ≃* N :=
mul_equiv_of_quotient f
end away
end localization
|
075c70362b3832d8577a27045a6614f691ebb932 | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/contradiction_issue.lean | 2fdb1bd81ba8d3d9e3750bdee79a29ab389b00e5 | [
"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 | 117 | lean | open tactic
def hd {α} : {l : list α // l ≠ []} → α
| ⟨[], h⟩ := by contradiction
| ⟨a::l, h⟩ := a
|
b56fc1bcfaa6dc6fde84556b2aebc43863423746 | c777c32c8e484e195053731103c5e52af26a25d1 | /src/algebraic_geometry/Spec.lean | 8663af3575c76bd9b4b4b791e45dcfe1e81d6fed | [
"Apache-2.0"
] | permissive | kbuzzard/mathlib | 2ff9e85dfe2a46f4b291927f983afec17e946eb8 | 58537299e922f9c77df76cb613910914a479c1f7 | refs/heads/master | 1,685,313,702,744 | 1,683,974,212,000 | 1,683,974,212,000 | 128,185,277 | 1 | 0 | null | 1,522,920,600,000 | 1,522,920,600,000 | null | UTF-8 | Lean | false | false | 15,650 | lean | /-
Copyright (c) 2020 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison, Justus Springer
-/
import algebraic_geometry.locally_ringed_space
import algebraic_geometry.structure_sheaf
import ring_theory.localization.localization_localization
import topology.sheaves.sheaf_condition.sites
import topology.sheaves.functors
import algebra.module.localized_module
/-!
# $Spec$ as a functor to locally ringed spaces.
We define the functor $Spec$ from commutative rings to locally ringed spaces.
## Implementation notes
We define $Spec$ in three consecutive steps, each with more structure than the last:
1. `Spec.to_Top`, valued in the category of topological spaces,
2. `Spec.to_SheafedSpace`, valued in the category of sheafed spaces and
3. `Spec.to_LocallyRingedSpace`, valued in the category of locally ringed spaces.
Additionally, we provide `Spec.to_PresheafedSpace` as a composition of `Spec.to_SheafedSpace` with
a forgetful functor.
## Related results
The adjunction `Γ ⊣ Spec` is constructed in `algebraic_geometry/Gamma_Spec_adjunction.lean`.
-/
noncomputable theory
universes u v
namespace algebraic_geometry
open opposite
open category_theory
open structure_sheaf Spec (structure_sheaf)
/--
The spectrum of a commutative ring, as a topological space.
-/
def Spec.Top_obj (R : CommRing) : Top := Top.of (prime_spectrum R)
/--
The induced map of a ring homomorphism on the ring spectra, as a morphism of topological spaces.
-/
def Spec.Top_map {R S : CommRing} (f : R ⟶ S) :
Spec.Top_obj S ⟶ Spec.Top_obj R :=
prime_spectrum.comap f
@[simp] lemma Spec.Top_map_id (R : CommRing) :
Spec.Top_map (𝟙 R) = 𝟙 (Spec.Top_obj R) :=
prime_spectrum.comap_id
lemma Spec.Top_map_comp {R S T : CommRing} (f : R ⟶ S) (g : S ⟶ T) :
Spec.Top_map (f ≫ g) = Spec.Top_map g ≫ Spec.Top_map f :=
prime_spectrum.comap_comp _ _
/--
The spectrum, as a contravariant functor from commutative rings to topological spaces.
-/
@[simps] def Spec.to_Top : CommRingᵒᵖ ⥤ Top :=
{ obj := λ R, Spec.Top_obj (unop R),
map := λ R S f, Spec.Top_map f.unop,
map_id' := λ R, by rw [unop_id, Spec.Top_map_id],
map_comp' := λ R S T f g, by rw [unop_comp, Spec.Top_map_comp] }
/--
The spectrum of a commutative ring, as a `SheafedSpace`.
-/
@[simps] def Spec.SheafedSpace_obj (R : CommRing) : SheafedSpace CommRing :=
{ carrier := Spec.Top_obj R,
presheaf := (structure_sheaf R).1,
is_sheaf := (structure_sheaf R).2 }
/--
The induced map of a ring homomorphism on the ring spectra, as a morphism of sheafed spaces.
-/
@[simps] def Spec.SheafedSpace_map {R S : CommRing.{u}} (f : R ⟶ S) :
Spec.SheafedSpace_obj S ⟶ Spec.SheafedSpace_obj R :=
{ base := Spec.Top_map f,
c :=
{ app := λ U, comap f (unop U) ((topological_space.opens.map (Spec.Top_map f)).obj (unop U))
(λ p, id),
naturality' := λ U V i, ring_hom.ext $ λ s, subtype.eq $ funext $ λ p, rfl } }
@[simp] lemma Spec.SheafedSpace_map_id {R : CommRing} :
Spec.SheafedSpace_map (𝟙 R) = 𝟙 (Spec.SheafedSpace_obj R) :=
PresheafedSpace.ext _ _ (Spec.Top_map_id R) $ nat_trans.ext _ _ $ funext $ λ U,
begin
dsimp,
erw [PresheafedSpace.id_c_app, comap_id], swap,
{ rw [Spec.Top_map_id, topological_space.opens.map_id_obj_unop] },
simpa [eq_to_hom_map],
end
lemma Spec.SheafedSpace_map_comp {R S T : CommRing} (f : R ⟶ S) (g : S ⟶ T) :
Spec.SheafedSpace_map (f ≫ g) = Spec.SheafedSpace_map g ≫ Spec.SheafedSpace_map f :=
PresheafedSpace.ext _ _ (Spec.Top_map_comp f g) $ nat_trans.ext _ _ $ funext $ λ U,
by { dsimp, rw category_theory.functor.map_id, rw category.comp_id, erw comap_comp f g, refl }
/--
Spec, as a contravariant functor from commutative rings to sheafed spaces.
-/
@[simps] def Spec.to_SheafedSpace : CommRingᵒᵖ ⥤ SheafedSpace CommRing :=
{ obj := λ R, Spec.SheafedSpace_obj (unop R),
map := λ R S f, Spec.SheafedSpace_map f.unop,
map_id' := λ R, by rw [unop_id, Spec.SheafedSpace_map_id],
map_comp' := λ R S T f g, by rw [unop_comp, Spec.SheafedSpace_map_comp] }
/--
Spec, as a contravariant functor from commutative rings to presheafed spaces.
-/
def Spec.to_PresheafedSpace : CommRingᵒᵖ ⥤ PresheafedSpace.{u} CommRing.{u} :=
Spec.to_SheafedSpace ⋙ SheafedSpace.forget_to_PresheafedSpace
@[simp] lemma Spec.to_PresheafedSpace_obj (R : CommRingᵒᵖ) :
Spec.to_PresheafedSpace.obj R = (Spec.SheafedSpace_obj (unop R)).to_PresheafedSpace := rfl
lemma Spec.to_PresheafedSpace_obj_op (R : CommRing) :
Spec.to_PresheafedSpace.obj (op R) = (Spec.SheafedSpace_obj R).to_PresheafedSpace := rfl
@[simp] lemma Spec.to_PresheafedSpace_map (R S : CommRingᵒᵖ) (f : R ⟶ S) :
Spec.to_PresheafedSpace.map f = Spec.SheafedSpace_map f.unop := rfl
lemma Spec.to_PresheafedSpace_map_op (R S : CommRing) (f : R ⟶ S) :
Spec.to_PresheafedSpace.map f.op = Spec.SheafedSpace_map f := rfl
lemma Spec.basic_open_hom_ext {X : RingedSpace} {R : CommRing} {α β : X ⟶ Spec.SheafedSpace_obj R}
(w : α.base = β.base) (h : ∀ r : R, let U := prime_spectrum.basic_open r in
(to_open R U ≫ α.c.app (op U)) ≫ X.presheaf.map (eq_to_hom (by rw w)) =
to_open R U ≫ β.c.app (op U)) : α = β :=
begin
ext1,
{ apply ((Top.sheaf.pushforward β.base).obj X.sheaf).hom_ext _
prime_spectrum.is_basis_basic_opens,
intro r,
apply (structure_sheaf.to_basic_open_epi R r).1,
simpa using h r },
exact w,
end
/--
The spectrum of a commutative ring, as a `LocallyRingedSpace`.
-/
@[simps] def Spec.LocallyRingedSpace_obj (R : CommRing) : LocallyRingedSpace :=
{ local_ring := λ x, @@ring_equiv.local_ring _
(show local_ring (localization.at_prime _), by apply_instance) _
(iso.CommRing_iso_to_ring_equiv $ stalk_iso R x).symm,
.. Spec.SheafedSpace_obj R }
@[elementwise]
lemma stalk_map_to_stalk {R S : CommRing} (f : R ⟶ S) (p : prime_spectrum S) :
to_stalk R (prime_spectrum.comap f p) ≫
PresheafedSpace.stalk_map (Spec.SheafedSpace_map f) p =
f ≫ to_stalk S p :=
begin
erw [← to_open_germ S ⊤ ⟨p, trivial⟩, ← to_open_germ R ⊤ ⟨prime_spectrum.comap f p, trivial⟩,
category.assoc, PresheafedSpace.stalk_map_germ (Spec.SheafedSpace_map f) ⊤ ⟨p, trivial⟩,
Spec.SheafedSpace_map_c_app, to_open_comp_comap_assoc],
refl
end
/--
Under the isomorphisms `stalk_iso`, the map `stalk_map (Spec.SheafedSpace_map f) p` corresponds
to the induced local ring homomorphism `localization.local_ring_hom`.
-/
@[elementwise]
lemma local_ring_hom_comp_stalk_iso {R S : CommRing} (f : R ⟶ S) (p : prime_spectrum S) :
(stalk_iso R (prime_spectrum.comap f p)).hom ≫
@category_struct.comp _ _
(CommRing.of (localization.at_prime (prime_spectrum.comap f p).as_ideal))
(CommRing.of (localization.at_prime p.as_ideal)) _
(localization.local_ring_hom (prime_spectrum.comap f p).as_ideal p.as_ideal f rfl)
(stalk_iso S p).inv =
PresheafedSpace.stalk_map (Spec.SheafedSpace_map f) p :=
(stalk_iso R (prime_spectrum.comap f p)).eq_inv_comp.mp $ (stalk_iso S p).comp_inv_eq.mpr $
localization.local_ring_hom_unique _ _ _ _ $ λ x, by
rw [stalk_iso_hom, stalk_iso_inv, comp_apply, comp_apply, localization_to_stalk_of,
stalk_map_to_stalk_apply, stalk_to_fiber_ring_hom_to_stalk]
/--
The induced map of a ring homomorphism on the prime spectra, as a morphism of locally ringed spaces.
-/
@[simps] def Spec.LocallyRingedSpace_map {R S : CommRing} (f : R ⟶ S) :
Spec.LocallyRingedSpace_obj S ⟶ Spec.LocallyRingedSpace_obj R :=
LocallyRingedSpace.hom.mk (Spec.SheafedSpace_map f) $ λ p, is_local_ring_hom.mk $ λ a ha,
begin
-- Here, we are showing that the map on prime spectra induced by `f` is really a morphism of
-- *locally* ringed spaces, i.e. that the induced map on the stalks is a local ring homomorphism.
rw ← local_ring_hom_comp_stalk_iso_apply at ha,
replace ha := (stalk_iso S p).hom.is_unit_map ha,
rw iso.inv_hom_id_apply at ha,
replace ha := is_local_ring_hom.map_nonunit _ ha,
convert ring_hom.is_unit_map (stalk_iso R (prime_spectrum.comap f p)).inv ha,
rw iso.hom_inv_id_apply
end
@[simp] lemma Spec.LocallyRingedSpace_map_id (R : CommRing) :
Spec.LocallyRingedSpace_map (𝟙 R) = 𝟙 (Spec.LocallyRingedSpace_obj R) :=
LocallyRingedSpace.hom.ext _ _ $
by { rw [Spec.LocallyRingedSpace_map_val, Spec.SheafedSpace_map_id], refl }
lemma Spec.LocallyRingedSpace_map_comp {R S T : CommRing} (f : R ⟶ S) (g : S ⟶ T) :
Spec.LocallyRingedSpace_map (f ≫ g) =
Spec.LocallyRingedSpace_map g ≫ Spec.LocallyRingedSpace_map f :=
LocallyRingedSpace.hom.ext _ _ $
by { rw [Spec.LocallyRingedSpace_map_val, Spec.SheafedSpace_map_comp], refl }
/--
Spec, as a contravariant functor from commutative rings to locally ringed spaces.
-/
@[simps] def Spec.to_LocallyRingedSpace : CommRingᵒᵖ ⥤ LocallyRingedSpace :=
{ obj := λ R, Spec.LocallyRingedSpace_obj (unop R),
map := λ R S f, Spec.LocallyRingedSpace_map f.unop,
map_id' := λ R, by rw [unop_id, Spec.LocallyRingedSpace_map_id],
map_comp' := λ R S T f g, by rw [unop_comp, Spec.LocallyRingedSpace_map_comp] }
section Spec_Γ
open algebraic_geometry.LocallyRingedSpace
/-- The counit morphism `R ⟶ Γ(Spec R)` given by `algebraic_geometry.structure_sheaf.to_open`. -/
@[simps {rhs_md := tactic.transparency.semireducible}]
def to_Spec_Γ (R : CommRing) : R ⟶ Γ.obj (op (Spec.to_LocallyRingedSpace.obj (op R))) :=
structure_sheaf.to_open R ⊤
instance is_iso_to_Spec_Γ (R : CommRing) : is_iso (to_Spec_Γ R) :=
by { cases R, apply structure_sheaf.is_iso_to_global }
@[reassoc]
lemma Spec_Γ_naturality {R S : CommRing} (f : R ⟶ S) :
f ≫ to_Spec_Γ S = to_Spec_Γ R ≫ Γ.map (Spec.to_LocallyRingedSpace.map f.op).op :=
by { ext, symmetry, apply localization.local_ring_hom_to_map }
/-- The counit (`Spec_Γ_identity.inv.op`) of the adjunction `Γ ⊣ Spec` is an isomorphism. -/
@[simps hom_app inv_app] def Spec_Γ_identity : Spec.to_LocallyRingedSpace.right_op ⋙ Γ ≅ 𝟭 _ :=
iso.symm $ nat_iso.of_components (λ R, as_iso (to_Spec_Γ R) : _) (λ _ _, Spec_Γ_naturality)
end Spec_Γ
/-- The stalk map of `Spec M⁻¹R ⟶ Spec R` is an iso for each `p : Spec M⁻¹R`. -/
lemma Spec_map_localization_is_iso (R : CommRing) (M : submonoid R)
(x : prime_spectrum (localization M)) :
is_iso (PresheafedSpace.stalk_map (Spec.to_PresheafedSpace.map
(CommRing.of_hom (algebra_map R (localization M))).op) x) :=
begin
erw ← local_ring_hom_comp_stalk_iso,
apply_with is_iso.comp_is_iso { instances := ff },
apply_instance,
apply_with is_iso.comp_is_iso { instances := ff },
/- I do not know why this is defeq to the goal, but I'm happy to accept that it is. -/
exact (show is_iso (is_localization.localization_localization_at_prime_iso_localization
M x.as_ideal).to_ring_equiv.to_CommRing_iso.hom, by apply_instance),
apply_instance
end
namespace structure_sheaf
variables {R S : CommRing.{u}} (f : R ⟶ S) (p : prime_spectrum R)
/--
For an algebra `f : R →+* S`, this is the ring homomorphism `S →+* (f∗ 𝒪ₛ)ₚ` for a `p : Spec R`.
This is shown to be the localization at `p` in `is_localized_module_to_pushforward_stalk_alg_hom`.
-/
def to_pushforward_stalk :
S ⟶ (Spec.Top_map f _* (structure_sheaf S).1).stalk p :=
structure_sheaf.to_open S ⊤ ≫
@Top.presheaf.germ _ _ _ _ (Spec.Top_map f _* (structure_sheaf S).1) ⊤ ⟨p, trivial⟩
@[reassoc]
lemma to_pushforward_stalk_comp :
f ≫ structure_sheaf.to_pushforward_stalk f p =
structure_sheaf.to_stalk R p ≫
(Top.presheaf.stalk_functor _ _).map (Spec.SheafedSpace_map f).c :=
begin
rw structure_sheaf.to_stalk,
erw category.assoc,
rw Top.presheaf.stalk_functor_map_germ,
exact Spec_Γ_naturality_assoc f _,
end
instance : algebra R ((Spec.Top_map f _* (structure_sheaf S).1).stalk p) :=
(f ≫ structure_sheaf.to_pushforward_stalk f p).to_algebra
lemma algebra_map_pushforward_stalk :
algebra_map R ((Spec.Top_map f _* (structure_sheaf S).1).stalk p) =
f ≫ structure_sheaf.to_pushforward_stalk f p := rfl
variables (R S) [algebra R S]
/--
This is the `alg_hom` version of `to_pushforward_stalk`, which is the map `S ⟶ (f∗ 𝒪ₛ)ₚ` for some
algebra `R ⟶ S` and some `p : Spec R`.
-/
@[simps]
def to_pushforward_stalk_alg_hom :
S →ₐ[R] (Spec.Top_map (algebra_map R S) _* (structure_sheaf S).1).stalk p :=
{ commutes' := λ _, rfl, ..(structure_sheaf.to_pushforward_stalk (algebra_map R S) p) }
lemma is_localized_module_to_pushforward_stalk_alg_hom_aux (y) :
∃ (x : S × p.as_ideal.prime_compl), x.2 • y = to_pushforward_stalk_alg_hom R S p x.1 :=
begin
obtain ⟨U, hp, s, e⟩ := Top.presheaf.germ_exist _ _ y,
obtain ⟨_, ⟨r, rfl⟩, hpr : p ∈ prime_spectrum.basic_open r,
hrU : prime_spectrum.basic_open r ≤ U⟩ := prime_spectrum.is_topological_basis_basic_opens
.exists_subset_of_mem_open (show p ∈ ↑U, from hp) U.2,
change prime_spectrum.basic_open r ≤ U at hrU,
replace e := ((Spec.Top_map (algebra_map R S) _* (structure_sheaf S).1)
.germ_res_apply (hom_of_le hrU) ⟨p, hpr⟩ _).trans e,
set s' := (Spec.Top_map (algebra_map R S) _* (structure_sheaf S).1).map (hom_of_le hrU).op s
with h,
rw ← h at e,
clear_value s', clear_dependent U,
obtain ⟨⟨s, ⟨_, n, rfl⟩⟩, hsn⟩ := @is_localization.surj _ _ _
_ _ _ (structure_sheaf.is_localization.to_basic_open S $ algebra_map R S r) s',
refine ⟨⟨s, ⟨r, hpr⟩ ^ n⟩, _⟩,
rw [submonoid.smul_def, algebra.smul_def, algebra_map_pushforward_stalk, to_pushforward_stalk,
comp_apply, comp_apply],
iterate 2 { erw ← (Spec.Top_map (algebra_map R S) _* (structure_sheaf S).1).germ_res_apply
(hom_of_le le_top) ⟨p, hpr⟩ },
rw [← e, ← map_mul, mul_comm],
dsimp only [subtype.coe_mk] at hsn,
rw ← map_pow (algebra_map R S) at hsn,
congr' 1
end
instance is_localized_module_to_pushforward_stalk_alg_hom :
is_localized_module p.as_ideal.prime_compl (to_pushforward_stalk_alg_hom R S p).to_linear_map :=
begin
apply is_localized_module.mk_of_algebra,
{ intros x hx, rw [algebra_map_pushforward_stalk, to_pushforward_stalk_comp, comp_apply],
exact (is_localization.map_units ((structure_sheaf R).presheaf.stalk p) ⟨x, hx⟩).map _ },
{ apply is_localized_module_to_pushforward_stalk_alg_hom_aux },
{ intros x hx,
rw [to_pushforward_stalk_alg_hom_apply, ring_hom.to_fun_eq_coe,
← (to_pushforward_stalk (algebra_map R S) p).map_zero, to_pushforward_stalk, comp_apply,
comp_apply, map_zero] at hx,
obtain ⟨U, hpU, i₁, i₂, e⟩ := Top.presheaf.germ_eq _ _ _ _ _ _ hx,
obtain ⟨_, ⟨r, rfl⟩, hpr, hrU⟩ := prime_spectrum.is_topological_basis_basic_opens
.exists_subset_of_mem_open (show p ∈ U.1, from hpU) U.2,
change prime_spectrum.basic_open r ≤ U at hrU,
apply_fun (Spec.Top_map (algebra_map R S) _* (structure_sheaf S).1).map (hom_of_le hrU).op at e,
simp only [Top.presheaf.pushforward_obj_map, functor.op_map, map_zero, ← comp_apply,
to_open_res] at e,
have : to_open S (prime_spectrum.basic_open $ algebra_map R S r) x = 0,
{ refine eq.trans _ e, refl },
have := (@is_localization.mk'_one _ _ _
_ _ _ (structure_sheaf.is_localization.to_basic_open S $ algebra_map R S r) x).trans this,
obtain ⟨⟨_, n, rfl⟩, e⟩ := (is_localization.mk'_eq_zero_iff _ _).mp this,
refine ⟨⟨r, hpr⟩ ^ n, _⟩,
rw [submonoid.smul_def, algebra.smul_def, submonoid.coe_pow, subtype.coe_mk, map_pow],
exact e },
end
end structure_sheaf
end algebraic_geometry
|
6107d7853f5ecb9d5e3bc9d56d27fa0934a4284f | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/category_theory/punit_auto.lean | 07dd5b110a9dd20660eebcecec7e8f3d82a2e029 | [] | 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 | 1,617 | 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 Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.category_theory.const
import Mathlib.category_theory.discrete_category
import Mathlib.PostPort
universes v u u_1
namespace Mathlib
namespace category_theory
namespace functor
/-- The constant functor sending everything to `punit.star`. -/
def star (C : Type u) [category C] : C ⥤ discrete PUnit := obj (const C) PUnit.unit
/-- Any two functors to `discrete punit` are isomorphic. -/
def punit_ext {C : Type u} [category C] (F : C ⥤ discrete PUnit) (G : C ⥤ discrete PUnit) : F ≅ G :=
nat_iso.of_components (fun (_x : C) => eq_to_iso sorry) sorry
/--
Any two functors to `discrete punit` are *equal*.
You probably want to use `punit_ext` instead of this.
-/
theorem punit_ext' {C : Type u} [category C] (F : C ⥤ discrete PUnit) (G : C ⥤ discrete PUnit) :
F = G :=
ext (fun (_x : C) => of_as_true trivial)
fun (_x _x_1 : C) (_x_2 : _x ⟶ _x_1) => of_as_true trivial
/-- The functor from `discrete punit` sending everything to the given object. -/
def from_punit {C : Type u} [category C] (X : C) : discrete PUnit ⥤ C :=
obj (const (discrete PUnit)) X
/-- Functors from `discrete punit` are equivalent to the category itself. -/
@[simp] theorem equiv_functor_obj {C : Type u} [category C] (F : discrete PUnit ⥤ C) :
obj (equivalence.functor equiv) F = obj F PUnit.unit :=
Eq.refl (obj (equivalence.functor equiv) F)
end Mathlib |
1b89e549fd4907418cbdc9b31133cd0b16e698c9 | 271e26e338b0c14544a889c31c30b39c989f2e0f | /tests/lean/run/typeclass_diamond.lean | 80b4eac0e4816fdf9d0aedecf3746063c4b89b31 | [
"Apache-2.0"
] | permissive | dgorokho/lean4 | 805f99b0b60c545b64ac34ab8237a8504f89d7d4 | e949a052bad59b1c7b54a82d24d516a656487d8a | refs/heads/master | 1,607,061,363,851 | 1,578,006,086,000 | 1,578,006,086,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 1,518 | lean | #exit
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 := {}
#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
|
b12d11a3d130b489a750a82a58e14f48da04dcd7 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/order/preorder_hom_auto.lean | cd554ac774219015e1b767d1ef8b0c1ef5d93fd7 | [] | 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 | 6,507 | lean | /-
Copyright (c) 2020 Johan Commelin. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johan Commelin
# Preorder homomorphisms
Bundled monotone functions, `x ≤ y → f x ≤ f y`.
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.logic.function.iterate
import Mathlib.order.basic
import Mathlib.order.bounded_lattice
import Mathlib.order.complete_lattice
import Mathlib.tactic.monotonicity.default
import Mathlib.PostPort
universes u_1 u_2 l u_3
namespace Mathlib
/-! # Category of preorders -/
/-- Bundled monotone (aka, increasing) function -/
structure preorder_hom (α : Type u_1) (β : Type u_2) [preorder α] [preorder β] where
to_fun : α → β
monotone' : monotone to_fun
infixr:25 " →ₘ " => Mathlib.preorder_hom
namespace preorder_hom
protected instance has_coe_to_fun {α : Type u_1} {β : Type u_2} [preorder α] [preorder β] :
has_coe_to_fun (α →ₘ β) :=
has_coe_to_fun.mk (fun (f : α →ₘ β) => α → β) to_fun
theorem monotone {α : Type u_1} {β : Type u_2} [preorder α] [preorder β] (f : α →ₘ β) :
monotone ⇑f :=
monotone' f
@[simp] theorem coe_fun_mk {α : Type u_1} {β : Type u_2} [preorder α] [preorder β] {f : α → β}
(hf : monotone f) (x : α) : coe_fn (mk f hf) x = f x :=
rfl
theorem ext {α : Type u_1} {β : Type u_2} [preorder α] [preorder β] (f : α →ₘ β) (g : α →ₘ β)
(h : ∀ (a : α), coe_fn f a = coe_fn g a) : f = g :=
sorry
theorem coe_inj {α : Type u_1} {β : Type u_2} [preorder α] [preorder β] (f : α →ₘ β) (g : α →ₘ β)
(h : ⇑f = ⇑g) : f = g :=
ext f g
fun (a : α) =>
eq.mpr (id (Eq._oldrec (Eq.refl (coe_fn f a = coe_fn g a)) h)) (Eq.refl (coe_fn g a))
/-- The identity function as bundled monotone function. -/
def id {α : Type u_1} [preorder α] : α →ₘ α := mk id monotone_id
protected instance inhabited {α : Type u_1} [preorder α] : Inhabited (α →ₘ α) := { default := id }
@[simp] theorem coe_id {α : Type u_1} [preorder α] : ⇑id = ⇑id := rfl
/-- The composition of two bundled monotone functions. -/
def comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [preorder α] [preorder β] [preorder γ]
(g : β →ₘ γ) (f : α →ₘ β) : α →ₘ γ :=
mk (⇑g ∘ ⇑f) sorry
@[simp] theorem comp_id {α : Type u_1} {β : Type u_2} [preorder α] [preorder β] (f : α →ₘ β) :
comp f id = f :=
ext (comp f id) f fun (a : α) => Eq.refl (coe_fn (comp f id) a)
@[simp] theorem id_comp {α : Type u_1} {β : Type u_2} [preorder α] [preorder β] (f : α →ₘ β) :
comp id f = f :=
ext (comp id f) f fun (a : α) => Eq.refl (coe_fn (comp id f) a)
/-- `subtype.val` as a bundled monotone function. -/
def subtype.val {α : Type u_1} [preorder α] (p : α → Prop) : Subtype p →ₘ α := mk subtype.val sorry
/-- The preorder structure of `α →ₘ β` is pointwise inequality: `f ≤ g ↔ ∀ a, f a ≤ g a`. -/
protected instance preorder {α : Type u_1} {β : Type u_2} [preorder α] [preorder β] :
preorder (α →ₘ β) :=
preorder.lift to_fun
protected instance partial_order {α : Type u_1} [preorder α] {β : Type u_2} [partial_order β] :
partial_order (α →ₘ β) :=
partial_order.lift to_fun sorry
protected instance has_sup {α : Type u_1} [preorder α] {β : Type u_2} [semilattice_sup β] :
has_sup (α →ₘ β) :=
has_sup.mk fun (f g : α →ₘ β) => mk (fun (a : α) => coe_fn f a ⊔ coe_fn g a) sorry
protected instance semilattice_sup {α : Type u_1} [preorder α] {β : Type u_2} [semilattice_sup β] :
semilattice_sup (α →ₘ β) :=
semilattice_sup.mk has_sup.sup partial_order.le partial_order.lt sorry sorry sorry sorry sorry
sorry
@[simp] theorem has_inf_inf_to_fun {α : Type u_1} [preorder α] {β : Type u_2} [semilattice_inf β]
(f : α →ₘ β) (g : α →ₘ β) (a : α) : coe_fn (f ⊓ g) a = coe_fn f a ⊓ coe_fn g a :=
Eq.refl (coe_fn (f ⊓ g) a)
protected instance semilattice_inf {α : Type u_1} [preorder α] {β : Type u_2} [semilattice_inf β] :
semilattice_inf (α →ₘ β) :=
semilattice_inf.mk has_inf.inf partial_order.le partial_order.lt sorry sorry sorry sorry sorry
sorry
protected instance lattice {α : Type u_1} [preorder α] {β : Type u_2} [lattice β] :
lattice (α →ₘ β) :=
lattice.mk semilattice_sup.sup semilattice_sup.le semilattice_sup.lt sorry sorry sorry sorry sorry
sorry semilattice_inf.inf sorry sorry sorry
protected instance has_bot {α : Type u_1} [preorder α] {β : Type u_2} [order_bot β] :
has_bot (α →ₘ β) :=
has_bot.mk (mk (fun (a : α) => ⊥) sorry)
protected instance order_bot {α : Type u_1} [preorder α] {β : Type u_2} [order_bot β] :
order_bot (α →ₘ β) :=
order_bot.mk ⊥ partial_order.le partial_order.lt sorry sorry sorry sorry
@[simp] theorem has_top_top_to_fun {α : Type u_1} [preorder α] {β : Type u_2} [order_top β]
(a : α) : coe_fn ⊤ a = ⊤ :=
Eq.refl (coe_fn ⊤ a)
protected instance order_top {α : Type u_1} [preorder α] {β : Type u_2} [order_top β] :
order_top (α →ₘ β) :=
order_top.mk ⊤ partial_order.le partial_order.lt sorry sorry sorry sorry
protected instance has_Inf {α : Type u_1} [preorder α] {β : Type u_2} [complete_lattice β] :
has_Inf (α →ₘ β) :=
has_Inf.mk
fun (s : set (α →ₘ β)) => mk (fun (x : α) => Inf ((fun (f : α →ₘ β) => coe_fn f x) '' s)) sorry
@[simp] theorem has_Sup_Sup_to_fun {α : Type u_1} [preorder α] {β : Type u_2} [complete_lattice β]
(s : set (α →ₘ β)) (x : α) : coe_fn (Sup s) x = Sup ((fun (f : α →ₘ β) => coe_fn f x) '' s) :=
Eq.refl (coe_fn (Sup s) x)
protected instance complete_lattice {α : Type u_1} [preorder α] {β : Type u_2}
[complete_lattice β] : complete_lattice (α →ₘ β) :=
complete_lattice.mk lattice.sup lattice.le lattice.lt sorry sorry sorry sorry sorry sorry
lattice.inf sorry sorry sorry order_top.top sorry order_bot.bot sorry Sup Inf sorry sorry sorry
sorry
theorem iterate_sup_le_sup_iff {α : Type u_1} [semilattice_sup α] (f : α →ₘ α) :
(∀ (n₁ n₂ : ℕ) (a₁ a₂ : α),
nat.iterate (⇑f) (n₁ + n₂) (a₁ ⊔ a₂) ≤ nat.iterate (⇑f) n₁ a₁ ⊔ nat.iterate (⇑f) n₂ a₂) ↔
∀ (a₁ a₂ : α), coe_fn f (a₁ ⊔ a₂) ≤ coe_fn f a₁ ⊔ a₂ :=
sorry
end Mathlib |
a95ee66275321e28d5a6d0873ae2062e26aa3f71 | 4950bf76e5ae40ba9f8491647d0b6f228ddce173 | /src/analysis/normed_space/bounded_linear_maps.lean | 46a24fa90e4f072cd1b400ca3b4c477e1add16b2 | [
"Apache-2.0"
] | permissive | ntzwq/mathlib | ca50b21079b0a7c6781c34b62199a396dd00cee2 | 36eec1a98f22df82eaccd354a758ef8576af2a7f | refs/heads/master | 1,675,193,391,478 | 1,607,822,996,000 | 1,607,822,996,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 21,263 | lean | /-
Copyright (c) 2018 Patrick Massot. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Patrick Massot, Johannes Hölzl
Continuous linear functions -- functions between normed vector spaces which are bounded and linear.
-/
import analysis.normed_space.multilinear
noncomputable theory
open_locale classical big_operators topological_space
open filter (tendsto)
open metric
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
variables {E : Type*} [normed_group E] [normed_space 𝕜 E]
variables {F : Type*} [normed_group F] [normed_space 𝕜 F]
variables {G : Type*} [normed_group G] [normed_space 𝕜 G]
/-- A function `f` satisfies `is_bounded_linear_map 𝕜 f` if it is linear and satisfies the
inequality `∥ f x ∥ ≤ M * ∥ x ∥` for some positive constant `M`. -/
structure is_bounded_linear_map (𝕜 : Type*) [normed_field 𝕜]
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{F : Type*} [normed_group F] [normed_space 𝕜 F] (f : E → F)
extends is_linear_map 𝕜 f : Prop :=
(bound : ∃ M, 0 < M ∧ ∀ x : E, ∥ f x ∥ ≤ M * ∥ x ∥)
lemma is_linear_map.with_bound
{f : E → F} (hf : is_linear_map 𝕜 f) (M : ℝ) (h : ∀ x : E, ∥ f x ∥ ≤ M * ∥ x ∥) :
is_bounded_linear_map 𝕜 f :=
⟨ hf, classical.by_cases
(assume : M ≤ 0, ⟨1, zero_lt_one, assume x,
le_trans (h x) $ mul_le_mul_of_nonneg_right (le_trans this zero_le_one) (norm_nonneg x)⟩)
(assume : ¬ M ≤ 0, ⟨M, lt_of_not_ge this, h⟩)⟩
/-- A continuous linear map satisfies `is_bounded_linear_map` -/
lemma continuous_linear_map.is_bounded_linear_map (f : E →L[𝕜] F) : is_bounded_linear_map 𝕜 f :=
{ bound := f.bound,
..f.to_linear_map.is_linear }
namespace is_bounded_linear_map
/-- Construct a linear map from a function `f` satisfying `is_bounded_linear_map 𝕜 f`. -/
def to_linear_map (f : E → F) (h : is_bounded_linear_map 𝕜 f) : E →ₗ[𝕜] F :=
(is_linear_map.mk' _ h.to_is_linear_map)
/-- Construct a continuous linear map from is_bounded_linear_map -/
def to_continuous_linear_map {f : E → F} (hf : is_bounded_linear_map 𝕜 f) : E →L[𝕜] F :=
{ cont := let ⟨C, Cpos, hC⟩ := hf.bound in linear_map.continuous_of_bound _ C hC,
..to_linear_map f hf}
lemma zero : is_bounded_linear_map 𝕜 (λ (x:E), (0:F)) :=
(0 : E →ₗ F).is_linear.with_bound 0 $ by simp [le_refl]
lemma id : is_bounded_linear_map 𝕜 (λ (x:E), x) :=
linear_map.id.is_linear.with_bound 1 $ by simp [le_refl]
lemma fst : is_bounded_linear_map 𝕜 (λ x : E × F, x.1) :=
begin
refine (linear_map.fst 𝕜 E F).is_linear.with_bound 1 (λx, _),
rw one_mul,
exact le_max_left _ _
end
lemma snd : is_bounded_linear_map 𝕜 (λ x : E × F, x.2) :=
begin
refine (linear_map.snd 𝕜 E F).is_linear.with_bound 1 (λx, _),
rw one_mul,
exact le_max_right _ _
end
variables { f g : E → F }
lemma smul (c : 𝕜) (hf : is_bounded_linear_map 𝕜 f) :
is_bounded_linear_map 𝕜 (λ e, c • f e) :=
let ⟨hlf, M, hMp, hM⟩ := hf in
(c • hlf.mk' f).is_linear.with_bound (∥c∥ * M) $ assume x,
calc ∥c • f x∥ = ∥c∥ * ∥f x∥ : norm_smul c (f x)
... ≤ ∥c∥ * (M * ∥x∥) : mul_le_mul_of_nonneg_left (hM _) (norm_nonneg _)
... = (∥c∥ * M) * ∥x∥ : (mul_assoc _ _ _).symm
lemma neg (hf : is_bounded_linear_map 𝕜 f) :
is_bounded_linear_map 𝕜 (λ e, -f e) :=
begin
rw show (λ e, -f e) = (λ e, (-1 : 𝕜) • f e), { funext, simp },
exact smul (-1) hf
end
lemma add (hf : is_bounded_linear_map 𝕜 f) (hg : is_bounded_linear_map 𝕜 g) :
is_bounded_linear_map 𝕜 (λ e, f e + g e) :=
let ⟨hlf, Mf, hMfp, hMf⟩ := hf in
let ⟨hlg, Mg, hMgp, hMg⟩ := hg in
(hlf.mk' _ + hlg.mk' _).is_linear.with_bound (Mf + Mg) $ assume x,
calc ∥f x + g x∥ ≤ Mf * ∥x∥ + Mg * ∥x∥ : norm_add_le_of_le (hMf x) (hMg x)
... ≤ (Mf + Mg) * ∥x∥ : by rw add_mul
lemma sub (hf : is_bounded_linear_map 𝕜 f) (hg : is_bounded_linear_map 𝕜 g) :
is_bounded_linear_map 𝕜 (λ e, f e - g e) :=
by simpa [sub_eq_add_neg] using add hf (neg hg)
lemma comp {g : F → G}
(hg : is_bounded_linear_map 𝕜 g) (hf : is_bounded_linear_map 𝕜 f) :
is_bounded_linear_map 𝕜 (g ∘ f) :=
(hg.to_continuous_linear_map.comp hf.to_continuous_linear_map).is_bounded_linear_map
protected lemma tendsto (x : E) (hf : is_bounded_linear_map 𝕜 f) :
tendsto f (𝓝 x) (𝓝 (f x)) :=
let ⟨hf, M, hMp, hM⟩ := hf in
tendsto_iff_norm_tendsto_zero.2 $
squeeze_zero (assume e, norm_nonneg _)
(assume e,
calc ∥f e - f x∥ = ∥hf.mk' f (e - x)∥ : by rw (hf.mk' _).map_sub e x; refl
... ≤ M * ∥e - x∥ : hM (e - x))
(suffices tendsto (λ (e : E), M * ∥e - x∥) (𝓝 x) (𝓝 (M * 0)), by simpa,
tendsto_const_nhds.mul (lim_norm _))
lemma continuous (hf : is_bounded_linear_map 𝕜 f) : continuous f :=
continuous_iff_continuous_at.2 $ λ _, hf.tendsto _
lemma lim_zero_bounded_linear_map (hf : is_bounded_linear_map 𝕜 f) :
tendsto f (𝓝 0) (𝓝 0) :=
(hf.1.mk' _).map_zero ▸ continuous_iff_continuous_at.1 hf.continuous 0
section
open asymptotics filter
theorem is_O_id {f : E → F} (h : is_bounded_linear_map 𝕜 f) (l : filter E) :
is_O f (λ x, x) l :=
let ⟨M, hMp, hM⟩ := h.bound in is_O.of_bound _ (mem_sets_of_superset univ_mem_sets (λ x _, hM x))
theorem is_O_comp {E : Type*} {g : F → G} (hg : is_bounded_linear_map 𝕜 g)
{f : E → F} (l : filter E) : is_O (λ x', g (f x')) f l :=
(hg.is_O_id ⊤).comp_tendsto le_top
theorem is_O_sub {f : E → F} (h : is_bounded_linear_map 𝕜 f)
(l : filter E) (x : E) : is_O (λ x', f (x' - x)) (λ x', x' - x) l :=
is_O_comp h l
end
end is_bounded_linear_map
section
variables {ι : Type*} [decidable_eq ι] [fintype ι]
/-- Taking the cartesian product of two continuous linear maps is a bounded linear operation. -/
lemma is_bounded_linear_map_prod_iso :
is_bounded_linear_map 𝕜 (λ(p : (E →L[𝕜] F) × (E →L[𝕜] G)), (p.1.prod p.2 : (E →L[𝕜] (F × G)))) :=
begin
refine is_linear_map.with_bound ⟨λu v, rfl, λc u, rfl⟩ 1 (λp, _),
simp only [norm, one_mul],
refine continuous_linear_map.op_norm_le_bound _ (le_trans (norm_nonneg _) (le_max_left _ _)) (λu, _),
simp only [norm, continuous_linear_map.prod, max_le_iff],
split,
{ calc ∥p.1 u∥ ≤ ∥p.1∥ * ∥u∥ : continuous_linear_map.le_op_norm _ _
... ≤ max (∥p.1∥) (∥p.2∥) * ∥u∥ :
mul_le_mul_of_nonneg_right (le_max_left _ _) (norm_nonneg _) },
{ calc ∥p.2 u∥ ≤ ∥p.2∥ * ∥u∥ : continuous_linear_map.le_op_norm _ _
... ≤ max (∥p.1∥) (∥p.2∥) * ∥u∥ :
mul_le_mul_of_nonneg_right (le_max_right _ _) (norm_nonneg _) }
end
/-- Taking the cartesian product of two continuous multilinear maps is a bounded linear operation. -/
lemma is_bounded_linear_map_prod_multilinear
{E : ι → Type*} [∀i, normed_group (E i)] [∀i, normed_space 𝕜 (E i)] :
is_bounded_linear_map 𝕜
(λ p : (continuous_multilinear_map 𝕜 E F) × (continuous_multilinear_map 𝕜 E G), p.1.prod p.2) :=
{ map_add := λ p₁ p₂, by { ext1 m, refl },
map_smul := λ c p, by { ext1 m, refl },
bound := ⟨1, zero_lt_one, λ p, begin
rw one_mul,
apply continuous_multilinear_map.op_norm_le_bound _ (norm_nonneg _) (λ m, _),
rw [continuous_multilinear_map.prod_apply, norm_prod_le_iff],
split,
{ exact le_trans (p.1.le_op_norm m)
(mul_le_mul_of_nonneg_right (norm_fst_le p) (finset.prod_nonneg (λ i hi, norm_nonneg _))) },
{ exact le_trans (p.2.le_op_norm m)
(mul_le_mul_of_nonneg_right (norm_snd_le p) (finset.prod_nonneg (λ i hi, norm_nonneg _))) },
end⟩ }
/-- Given a fixed continuous linear map `g`, associating to a continuous multilinear map `f` the
continuous multilinear map `f (g m₁, ..., g mₙ)` is a bounded linear operation. -/
lemma is_bounded_linear_map_continuous_multilinear_map_comp_linear (g : G →L[𝕜] E) :
is_bounded_linear_map 𝕜 (λ f : continuous_multilinear_map 𝕜 (λ (i : ι), E) F,
f.comp_continuous_linear_map (λ _, g)) :=
begin
refine is_linear_map.with_bound ⟨λ f₁ f₂, by { ext m, refl }, λ c f, by { ext m, refl }⟩
(∥g∥ ^ (fintype.card ι)) (λ f, _),
apply continuous_multilinear_map.op_norm_le_bound _ _ (λ m, _),
{ apply_rules [mul_nonneg, pow_nonneg, norm_nonneg] },
calc ∥f (g ∘ m)∥ ≤
∥f∥ * ∏ i, ∥g (m i)∥ : f.le_op_norm _
... ≤ ∥f∥ * ∏ i, (∥g∥ * ∥m i∥) : begin
apply mul_le_mul_of_nonneg_left _ (norm_nonneg _),
exact finset.prod_le_prod (λ i hi, norm_nonneg _) (λ i hi, g.le_op_norm _)
end
... = ∥g∥ ^ fintype.card ι * ∥f∥ * ∏ i, ∥m i∥ :
by { simp [finset.prod_mul_distrib, finset.card_univ], ring }
end
end
section bilinear_map
variable (𝕜)
/-- A map `f : E × F → G` satisfies `is_bounded_bilinear_map 𝕜 f` if it is bilinear and
continuous. -/
structure is_bounded_bilinear_map (f : E × F → G) : Prop :=
(add_left : ∀(x₁ x₂ : E) (y : F), f (x₁ + x₂, y) = f (x₁, y) + f (x₂, y))
(smul_left : ∀(c : 𝕜) (x : E) (y : F), f (c • x, y) = c • f (x,y))
(add_right : ∀(x : E) (y₁ y₂ : F), f (x, y₁ + y₂) = f (x, y₁) + f (x, y₂))
(smul_right : ∀(c : 𝕜) (x : E) (y : F), f (x, c • y) = c • f (x,y))
(bound : ∃C>0, ∀(x : E) (y : F), ∥f (x, y)∥ ≤ C * ∥x∥ * ∥y∥)
variable {𝕜}
variable {f : E × F → G}
protected lemma is_bounded_bilinear_map.is_O (h : is_bounded_bilinear_map 𝕜 f) :
asymptotics.is_O f (λ p : E × F, ∥p.1∥ * ∥p.2∥) ⊤ :=
let ⟨C, Cpos, hC⟩ := h.bound in asymptotics.is_O.of_bound _ $
filter.eventually_of_forall $ λ ⟨x, y⟩, by simpa [mul_assoc] using hC x y
lemma is_bounded_bilinear_map.is_O_comp {α : Type*} (H : is_bounded_bilinear_map 𝕜 f)
{g : α → E} {h : α → F} {l : filter α} :
asymptotics.is_O (λ x, f (g x, h x)) (λ x, ∥g x∥ * ∥h x∥) l :=
H.is_O.comp_tendsto le_top
protected lemma is_bounded_bilinear_map.is_O' (h : is_bounded_bilinear_map 𝕜 f) :
asymptotics.is_O f (λ p : E × F, ∥p∥ * ∥p∥) ⊤ :=
h.is_O.trans (asymptotics.is_O_fst_prod'.norm_norm.mul asymptotics.is_O_snd_prod'.norm_norm)
lemma is_bounded_bilinear_map.map_sub_left (h : is_bounded_bilinear_map 𝕜 f) {x y : E} {z : F} :
f (x - y, z) = f (x, z) - f(y, z) :=
calc f (x - y, z) = f (x + (-1 : 𝕜) • y, z) : by simp [sub_eq_add_neg]
... = f (x, z) + (-1 : 𝕜) • f (y, z) : by simp only [h.add_left, h.smul_left]
... = f (x, z) - f (y, z) : by simp [sub_eq_add_neg]
lemma is_bounded_bilinear_map.map_sub_right (h : is_bounded_bilinear_map 𝕜 f) {x : E} {y z : F} :
f (x, y - z) = f (x, y) - f (x, z) :=
calc f (x, y - z) = f (x, y + (-1 : 𝕜) • z) : by simp [sub_eq_add_neg]
... = f (x, y) + (-1 : 𝕜) • f (x, z) : by simp only [h.add_right, h.smul_right]
... = f (x, y) - f (x, z) : by simp [sub_eq_add_neg]
lemma is_bounded_bilinear_map.is_bounded_linear_map_left (h : is_bounded_bilinear_map 𝕜 f) (y : F) :
is_bounded_linear_map 𝕜 (λ x, f (x, y)) :=
{ map_add := λ x x', h.add_left _ _ _,
map_smul := λ c x, h.smul_left _ _ _,
bound := begin
rcases h.bound with ⟨C, C_pos, hC⟩,
refine ⟨C * (∥y∥ + 1), mul_pos C_pos (lt_of_lt_of_le (zero_lt_one) (by simp)), λ x, _⟩,
have : ∥y∥ ≤ ∥y∥ + 1, by simp [zero_le_one],
calc ∥f (x, y)∥ ≤ C * ∥x∥ * ∥y∥ : hC x y
... ≤ C * ∥x∥ * (∥y∥ + 1) :
by apply_rules [norm_nonneg, mul_le_mul_of_nonneg_left, le_of_lt C_pos, mul_nonneg]
... = C * (∥y∥ + 1) * ∥x∥ : by ring
end }
lemma is_bounded_bilinear_map.is_bounded_linear_map_right (h : is_bounded_bilinear_map 𝕜 f) (x : E) :
is_bounded_linear_map 𝕜 (λ y, f (x, y)) :=
{ map_add := λ y y', h.add_right _ _ _,
map_smul := λ c y, h.smul_right _ _ _,
bound := begin
rcases h.bound with ⟨C, C_pos, hC⟩,
refine ⟨C * (∥x∥ + 1), mul_pos C_pos (lt_of_lt_of_le (zero_lt_one) (by simp)), λ y, _⟩,
have : ∥x∥ ≤ ∥x∥ + 1, by simp [zero_le_one],
calc ∥f (x, y)∥ ≤ C * ∥x∥ * ∥y∥ : hC x y
... ≤ C * (∥x∥ + 1) * ∥y∥ :
by apply_rules [mul_le_mul_of_nonneg_right, norm_nonneg, mul_le_mul_of_nonneg_left,
le_of_lt C_pos]
end }
lemma is_bounded_bilinear_map_smul :
is_bounded_bilinear_map 𝕜 (λ (p : 𝕜 × E), p.1 • p.2) :=
{ add_left := add_smul,
smul_left := λc x y, by simp [smul_smul],
add_right := smul_add,
smul_right := λc x y, by simp [smul_smul, mul_comm],
bound := ⟨1, zero_lt_one, λx y, by simp [norm_smul]⟩ }
lemma is_bounded_bilinear_map_smul_algebra {𝕜' : Type*} [normed_field 𝕜']
[normed_algebra 𝕜 𝕜'] {E : Type*} [normed_group E] [normed_space 𝕜 E] [normed_space 𝕜' E]
[is_scalar_tower 𝕜 𝕜' E] :
is_bounded_bilinear_map 𝕜 (λ (p : 𝕜' × E), p.1 • p.2) :=
{ add_left := add_smul,
smul_left := λ c x y, by simp [smul_assoc],
add_right := smul_add,
smul_right := λ c x y, by simp [smul_assoc, smul_algebra_smul_comm],
bound := ⟨1, zero_lt_one, λ x y, by simp [norm_smul] ⟩ }
lemma is_bounded_bilinear_map_mul :
is_bounded_bilinear_map 𝕜 (λ (p : 𝕜 × 𝕜), p.1 * p.2) :=
is_bounded_bilinear_map_smul
lemma is_bounded_bilinear_map_comp :
is_bounded_bilinear_map 𝕜 (λ(p : (E →L[𝕜] F) × (F →L[𝕜] G)), p.2.comp p.1) :=
{ add_left := λx₁ x₂ y, begin
ext z,
change y (x₁ z + x₂ z) = y (x₁ z) + y (x₂ z),
rw y.map_add
end,
smul_left := λc x y, begin
ext z,
change y (c • (x z)) = c • y (x z),
rw continuous_linear_map.map_smul
end,
add_right := λx y₁ y₂, rfl,
smul_right := λc x y, rfl,
bound := ⟨1, zero_lt_one, λx y, calc
∥continuous_linear_map.comp ((x, y).snd) ((x, y).fst)∥
≤ ∥y∥ * ∥x∥ : continuous_linear_map.op_norm_comp_le _ _
... = 1 * ∥x∥ * ∥ y∥ : by ring ⟩ }
lemma continuous_linear_map.is_bounded_linear_map_comp_left (g : continuous_linear_map 𝕜 F G) :
is_bounded_linear_map 𝕜 (λ(f : E →L[𝕜] F), continuous_linear_map.comp g f) :=
is_bounded_bilinear_map_comp.is_bounded_linear_map_left _
lemma continuous_linear_map.is_bounded_linear_map_comp_right (f : continuous_linear_map 𝕜 E F) :
is_bounded_linear_map 𝕜 (λ(g : F →L[𝕜] G), continuous_linear_map.comp g f) :=
is_bounded_bilinear_map_comp.is_bounded_linear_map_right _
lemma is_bounded_bilinear_map_apply :
is_bounded_bilinear_map 𝕜 (λp : (E →L[𝕜] F) × E, p.1 p.2) :=
{ add_left := by simp,
smul_left := by simp,
add_right := by simp,
smul_right := by simp,
bound := ⟨1, zero_lt_one, by simp [continuous_linear_map.le_op_norm]⟩ }
/-- The function `continuous_linear_map.smul_right`, associating to a continuous linear map
`f : E → 𝕜` and a scalar `c : F` the tensor product `f ⊗ c` as a continuous linear map from `E` to
`F`, is a bounded bilinear map. -/
lemma is_bounded_bilinear_map_smul_right :
is_bounded_bilinear_map 𝕜
(λp, (continuous_linear_map.smul_right : (E →L[𝕜] 𝕜) → F → (E →L[𝕜] F)) p.1 p.2) :=
{ add_left := λm₁ m₂ f, by { ext z, simp [add_smul] },
smul_left := λc m f, by { ext z, simp [mul_smul] },
add_right := λm f₁ f₂, by { ext z, simp [smul_add] },
smul_right := λc m f, by { ext z, simp [smul_smul, mul_comm] },
bound := ⟨1, zero_lt_one, λm f, by simp⟩ }
/-- The composition of a continuous linear map with a continuous multilinear map is a bounded
bilinear operation. -/
lemma is_bounded_bilinear_map_comp_multilinear {ι : Type*} {E : ι → Type*}
[decidable_eq ι] [fintype ι] [∀i, normed_group (E i)] [∀i, normed_space 𝕜 (E i)] :
is_bounded_bilinear_map 𝕜 (λ p : (F →L[𝕜] G) × (continuous_multilinear_map 𝕜 E F),
p.1.comp_continuous_multilinear_map p.2) :=
{ add_left := λ g₁ g₂ f, by { ext m, refl },
smul_left := λ c g f, by { ext m, refl },
add_right := λ g f₁ f₂, by { ext m, simp },
smul_right := λ c g f, by { ext m, simp },
bound := ⟨1, zero_lt_one, λ g f, begin
apply continuous_multilinear_map.op_norm_le_bound _ _ (λm, _),
{ apply_rules [mul_nonneg, zero_le_one, norm_nonneg] },
calc ∥g (f m)∥ ≤ ∥g∥ * ∥f m∥ : g.le_op_norm _
... ≤ ∥g∥ * (∥f∥ * ∏ i, ∥m i∥) :
mul_le_mul_of_nonneg_left (f.le_op_norm _) (norm_nonneg _)
... = 1 * ∥g∥ * ∥f∥ * ∏ i, ∥m i∥ : by ring
end⟩ }
/-- Definition of the derivative of a bilinear map `f`, given at a point `p` by
`q ↦ f(p.1, q.2) + f(q.1, p.2)` as in the standard formula for the derivative of a product.
We define this function here a bounded linear map from `E × F` to `G`. The fact that this
is indeed the derivative of `f` is proved in `is_bounded_bilinear_map.has_fderiv_at` in
`fderiv.lean`-/
def is_bounded_bilinear_map.linear_deriv (h : is_bounded_bilinear_map 𝕜 f) (p : E × F) :
(E × F) →ₗ[𝕜] G :=
{ to_fun := λq, f (p.1, q.2) + f (q.1, p.2),
map_add' := λq₁ q₂, begin
change f (p.1, q₁.2 + q₂.2) + f (q₁.1 + q₂.1, p.2) =
f (p.1, q₁.2) + f (q₁.1, p.2) + (f (p.1, q₂.2) + f (q₂.1, p.2)),
simp [h.add_left, h.add_right], abel
end,
map_smul' := λc q, begin
change f (p.1, c • q.2) + f (c • q.1, p.2) = c • (f (p.1, q.2) + f (q.1, p.2)),
simp [h.smul_left, h.smul_right, smul_add]
end }
/-- The derivative of a bounded bilinear map at a point `p : E × F`, as a continuous linear map
from `E × F` to `G`. -/
def is_bounded_bilinear_map.deriv (h : is_bounded_bilinear_map 𝕜 f) (p : E × F) : (E × F) →L[𝕜] G :=
(h.linear_deriv p).mk_continuous_of_exists_bound $ begin
rcases h.bound with ⟨C, Cpos, hC⟩,
refine ⟨C * ∥p.1∥ + C * ∥p.2∥, λq, _⟩,
calc ∥f (p.1, q.2) + f (q.1, p.2)∥
≤ C * ∥p.1∥ * ∥q.2∥ + C * ∥q.1∥ * ∥p.2∥ : norm_add_le_of_le (hC _ _) (hC _ _)
... ≤ C * ∥p.1∥ * ∥q∥ + C * ∥q∥ * ∥p.2∥ : begin
apply add_le_add,
exact mul_le_mul_of_nonneg_left (le_max_right _ _) (mul_nonneg (le_of_lt Cpos) (norm_nonneg _)),
apply mul_le_mul_of_nonneg_right _ (norm_nonneg _),
exact mul_le_mul_of_nonneg_left (le_max_left _ _) (le_of_lt Cpos),
end
... = (C * ∥p.1∥ + C * ∥p.2∥) * ∥q∥ : by ring
end
@[simp] lemma is_bounded_bilinear_map_deriv_coe (h : is_bounded_bilinear_map 𝕜 f) (p q : E × F) :
h.deriv p q = f (p.1, q.2) + f (q.1, p.2) := rfl
variables (𝕜)
/-- The function `lmul_left_right : 𝕜' × 𝕜' → (𝕜' →L[𝕜] 𝕜')` is a bounded bilinear map. -/
lemma continuous_linear_map.lmul_left_right_is_bounded_bilinear
(𝕜' : Type*) [normed_ring 𝕜'] [normed_algebra 𝕜 𝕜'] :
is_bounded_bilinear_map 𝕜 (continuous_linear_map.lmul_left_right 𝕜 𝕜') :=
{ add_left := λ v₁ v₂ w, by {ext t, simp [add_comm, add_mul]},
smul_left := λ c v w, by {ext, simp },
add_right := λ v w₁ w₂, by {ext t, simp [add_comm, mul_add]},
smul_right := λ c v w, by {ext, simp },
bound := begin
refine ⟨1, by linarith, _⟩,
intros v w,
rw one_mul,
apply continuous_linear_map.lmul_left_right_norm_le,
end }
variables {𝕜}
/-- Given a bounded bilinear map `f`, the map associating to a point `p` the derivative of `f` at
`p` is itself a bounded linear map. -/
lemma is_bounded_bilinear_map.is_bounded_linear_map_deriv (h : is_bounded_bilinear_map 𝕜 f) :
is_bounded_linear_map 𝕜 (λp : E × F, h.deriv p) :=
begin
rcases h.bound with ⟨C, Cpos, hC⟩,
refine is_linear_map.with_bound ⟨λp₁ p₂, _, λc p, _⟩ (C + C) (λp, _),
{ ext q,
simp [h.add_left, h.add_right], abel },
{ ext q,
simp [h.smul_left, h.smul_right, smul_add] },
{ refine continuous_linear_map.op_norm_le_bound _
(mul_nonneg (add_nonneg (le_of_lt Cpos) (le_of_lt Cpos)) (norm_nonneg _)) (λq, _),
calc ∥f (p.1, q.2) + f (q.1, p.2)∥
≤ C * ∥p.1∥ * ∥q.2∥ + C * ∥q.1∥ * ∥p.2∥ : norm_add_le_of_le (hC _ _) (hC _ _)
... ≤ C * ∥p∥ * ∥q∥ + C * ∥q∥ * ∥p∥ : by apply_rules [add_le_add, mul_le_mul, norm_nonneg,
le_of_lt Cpos, le_refl, le_max_left, le_max_right, mul_nonneg]
... = (C + C) * ∥p∥ * ∥q∥ : by ring },
end
end bilinear_map
/-- A linear isometry preserves the norm. -/
lemma linear_map.norm_apply_of_isometry (f : E →ₗ[𝕜] F) {x : E} (hf : isometry f) : ∥f x∥ = ∥x∥ :=
by { simp_rw [←dist_zero_right, ←f.map_zero], exact isometry.dist_eq hf _ _ }
/-- Construct a continuous linear equiv from a linear map that is also an isometry with full range. -/
def continuous_linear_equiv.of_isometry (f : E →ₗ[𝕜] F) (hf : isometry f) (hfr : f.range = ⊤) :
E ≃L[𝕜] F :=
continuous_linear_equiv.of_homothety 𝕜
(linear_equiv.of_bijective f (linear_map.ker_eq_bot.mpr (isometry.injective hf)) hfr)
1 zero_lt_one (λ _, by simp [one_mul, f.norm_apply_of_isometry hf])
|
84c0c1ccacaf413004724a922dd5433073f8afa6 | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/1327.lean | b1f546483de0b46042af1bc42957627bfcfae9c3 | [
"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 | 76 | lean | example (n) : nat.pred n = n :=
begin
dsimp {fail_if_unchanged := ff}
end
|
d8968aa0834b3984b141919b0e9bd84f3d0062fc | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /tests/lean/UnexpandSubtype.lean | ae19d79d6405db07d3f7a425eb89a90e9ec472d3 | [
"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 | 163 | lean | set_option pp.analyze false
set_option pp.funBinderTypes false in
#check { x : Nat // x < 10 }
set_option pp.funBinderTypes true in
#check { x : Nat // x < 10 }
|
a0717ddc9fcd0ae8d0a33d2d7249045d75cf9ace | 8b9f17008684d796c8022dab552e42f0cb6fb347 | /library/data/default.lean | 0351c7537d6e8c7ea62828b4849991641fdad05c | [
"Apache-2.0"
] | permissive | chubbymaggie/lean | 0d06ae25f9dd396306fb02190e89422ea94afd7b | d2c7b5c31928c98f545b16420d37842c43b4ae9a | refs/heads/master | 1,611,313,622,901 | 1,430,266,839,000 | 1,430,267,083,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 293 | lean | /-
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Module: data.default
Author: Jeremy Avigad
-/
import .empty .unit .bool .num .string .nat .int
import .prod .sum .sigma .option .subtype .quotient .list .set
|
28665c315286c93483b7f4a45dc769df2637857c | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /test/lint.lean | e3cdf87c66eb8144f7f31e8de36e93223adaa3f2 | [
"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 | 4,556 | lean | import tactic.lint
import algebra.ring.basic
open tactic
def foo1 (n m : ℕ) : ℕ := n + 1
def foo2 (n m : ℕ) : m = m := by refl
noncomputable lemma foo3 (n m : ℕ) : ℕ := n - m
lemma foo.foo (n m : ℕ) : n ≥ n := le_refl n
instance bar.bar : has_add ℕ := by apply_instance -- we don't check the name of instances
lemma foo.bar (ε > 0) : ε = ε := rfl -- >/≥ is allowed in binders (and in fact, in all hypotheses)
/-- Test exception in `def_lemma` linter. -/
@[pattern] def my_exists_intro := @Exists.intro
meta def fold_over_with_cond {α} (l : list declaration) (tac : declaration → tactic (option α)) :
tactic (list (declaration × α)) :=
l.mmap_filter $ λ d, option.map (λ x, (d, x)) <$> tac d
run_cmd do
let t := name × list ℕ,
e ← get_env,
let l := e.filter (λ d, e.in_current_file d.to_name ∧ ¬ d.is_auto_or_internal e),
l2 ← fold_over_with_cond l (return ∘ check_unused_arguments),
guard (l2.length = 4) <|> fail "wrong length",
let l2 : list (name × list ℕ) := l2.map (λ x, ⟨x.1.to_name, x.2⟩),
guard ((⟨`foo1, [2]⟩ : t) ∈ l2) <|> fail "foo1",
guard ((⟨`foo2, [1]⟩ : t) ∈ l2) <|> fail "foo2",
guard ((⟨`foo.foo, [2]⟩ : t) ∈ l2) <|> fail "foofoo",
guard ((⟨`foo.bar, [2]⟩ : t) ∈ l2) <|> fail "foobar",
l2 ← fold_over_with_cond l linter.def_lemma.test,
guard $ l2.length = 2,
let l2 : list (name × _) := l2.map $ λ x, ⟨x.1.to_name, x.2⟩,
guard $ ∃(x ∈ l2), (x : name × _).1 = `foo2,
guard $ ∃(x ∈ l2), (x : name × _).1 = `foo3,
l3 ← fold_over_with_cond l linter.dup_namespace.test,
guard $ l3.length = 1,
guard $ ∃(x ∈ l3), (x : declaration × _).1.to_name = `foo.foo,
l4 ← fold_over_with_cond l linter.ge_or_gt.test,
guard $ l4.length = 1,
guard $ ∃(x ∈ l4), (x : declaration × _).1.to_name = `foo.foo,
-- guard $ ∃(x ∈ l4), (x : declaration × _).1.to_name = `foo4,
(_, s) ← lint ff,
guard $ "/- (slow tests skipped) -/\n".is_suffix_of s.to_string,
(_, s2) ← lint tt,
guard $ s.to_string ≠ s2.to_string,
skip
/- check customizability and nolint -/
meta def dummy_check (d : declaration) : tactic (option string) :=
return $ if d.to_name.last = "foo" then some "gotcha!" else none
meta def linter.dummy_linter : linter :=
{ test := dummy_check,
auto_decls := ff,
no_errors_found := "found nothing.",
errors_found := "found something:" }
@[nolint dummy_linter]
def bar.foo : (if 3 = 3 then 1 else 2) = 1 := if_pos (by refl)
run_cmd do
(_, s) ← lint tt lint_verbosity.medium [`linter.dummy_linter] tt,
guard $ "/- found something: -/\n#check @foo.foo /- gotcha! -/\n".is_suffix_of s.to_string
def incorrect_type_class_argument_test {α : Type} (x : α) [x = x] [decidable_eq α] [group α] :
unit := ()
run_cmd do
d ← get_decl `incorrect_type_class_argument_test,
x ← linter.incorrect_type_class_argument.test d,
guard $ x = some "These are not classes. argument 3: [_inst_1 : x = x]"
section
def impossible_instance_test {α β : Type} [add_group α] : has_add α := infer_instance
local attribute [instance] impossible_instance_test
run_cmd do
d ← get_decl `impossible_instance_test,
x ← linter.impossible_instance.test d,
guard $ x = some "Impossible to infer argument 2: {β : Type}"
def dangerous_instance_test {α β γ : Type} [ring α] [add_comm_group β] [has_coe α β]
[has_inv γ] : has_add β := infer_instance
local attribute [instance] dangerous_instance_test
run_cmd do
d ← get_decl `dangerous_instance_test,
x ← linter.dangerous_instance.test d,
guard $ x = some
"The following arguments become metavariables. argument 1: {α : Type}, argument 3: {γ : Type}"
end
section
def foo_has_mul {α} [has_mul α] : has_mul α := infer_instance
local attribute [instance, priority 1] foo_has_mul
run_cmd do
d ← get_decl `foo_has_mul,
some s ← fails_quickly 20 d,
guard $ "type-class inference timed out".is_prefix_of s
local attribute [instance, priority 10000] foo_has_mul
run_cmd do
d ← get_decl `foo_has_mul,
some s ← fails_quickly 3000 d,
guard $ "maximum class-instance resolution depth has been reached".is_prefix_of s
end
instance beta_redex_test {α} [monoid α] : (λ (X : Type), has_mul X) α := ⟨(*)⟩
run_cmd do
d ← get_decl `beta_redex_test,
x ← linter.instance_priority.test d,
guard $ x = some "set priority below 1000"
/- Test exception in `def_lemma` linter. -/
run_cmd do
d ← get_decl `my_exists_intro,
t ← linter.def_lemma.test d,
guard $ t = none
|
fe1f0b63b09c1d21740ea8af5eb0ca22b100c7c3 | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/1260.lean | ccfef940c222e6a8bd242d1766322bad82d4b085 | [
"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 | 1,151 | lean | inductive dvec {X : Type} (Y : X → Type) : list X → Type
| dnil {} : dvec []
| dcons : Π {x : X}, Y x → Π {xs : list X}, dvec xs → dvec (x::xs)
namespace dvec
notation `⟦` l:(foldr `, ` (h t, dvec.dcons h t) dvec.dnil `⟧`) := l
def get {X : Type} [decidable_eq X] {Y : X → Type} (x₀ : X) [inhabited (Y x₀)]
: Π {xs : list X}, dvec Y xs → ℕ → Y x₀
| [] _ _ := default
| (x::xs) (dvec.dcons y ys) 0 := if H : x = x₀ then eq.rec_on H y else default
| (x::xs) (dvec.dcons y ys) (n+1) := get ys n
end dvec
constant tensor : list ℕ → Type
noncomputable instance inhabited_tensor (shape : list ℕ) : inhabited (tensor shape) := sorry
constant f {shape : list ℕ} : tensor shape → tensor shape → tensor shape
noncomputable def bar {shape : list ℕ} (μσ : dvec tensor [shape, shape]) : tensor shape :=
let μ := dvec.get shape μσ 0, σ := dvec.get shape μσ 1 in f μ σ
lemma foo {shape : list ℕ} (μ σ : tensor shape) :
bar ⟦μ, σ⟧ = bar ⟦μ, σ⟧ :=
suffices H_suffices : true, from
begin
dunfold bar, dsimp,
dunfold dvec.get,
reflexivity
end,
trivial
|
2b3e56865015699d3184b3a5fb8ff405b4018a33 | 618003631150032a5676f229d13a079ac875ff77 | /src/category_theory/limits/opposites.lean | d285bb1a8ae37d4379b078fa4f90f4b19d7a2598 | [
"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 | 3,653 | lean | /-
Copyright (c) 2019 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison, Floris van Doorn
-/
import category_theory.limits.limits
import category_theory.discrete_category
universes v u
open category_theory
open category_theory.functor
open opposite
namespace category_theory.limits
variables {C : Type u} [category.{v} C]
variables {J : Type v} [small_category J]
variable (F : J ⥤ Cᵒᵖ)
instance has_limit_of_has_colimit_left_op [has_colimit.{v} F.left_op] : has_limit.{v} F :=
{ cone := cone_of_cocone_left_op (colimit.cocone F.left_op),
is_limit :=
{ lift := λ s, (colimit.desc F.left_op (cocone_left_op_of_cone s)).op,
fac' := λ s j,
begin
rw [cone_of_cocone_left_op_π_app, colimit.cocone_ι, ←op_comp,
colimit.ι_desc, cocone_left_op_of_cone_ι_app, has_hom.hom.op_unop],
refl, end,
uniq' := λ s m w,
begin
-- It's a pity we can't do this automatically.
-- Usually something like this would work by limit.hom_ext,
-- but the opposites get in the way of this firing.
have u := (colimit.is_colimit F.left_op).uniq (cocone_left_op_of_cone s) (m.unop),
convert congr_arg (λ f : _ ⟶ _, f.op) (u _), clear u,
intro j,
rw [cocone_left_op_of_cone_ι_app, colimit.cocone_ι],
convert congr_arg (λ f : _ ⟶ _, f.unop) (w (unop j)), clear w,
rw [cone_of_cocone_left_op_π_app, colimit.cocone_ι, has_hom.hom.unop_op],
refl,
end } }
instance has_limits_of_shape_op_of_has_colimits_of_shape [has_colimits_of_shape.{v} Jᵒᵖ C] :
has_limits_of_shape.{v} J Cᵒᵖ :=
{ has_limit := λ F, by apply_instance }
instance has_limits_op_of_has_colimits [has_colimits.{v} C] : has_limits.{v} Cᵒᵖ :=
{ has_limits_of_shape := λ J 𝒥, by { resetI, apply_instance } }
instance has_colimit_of_has_limit_left_op [has_limit.{v} F.left_op] : has_colimit.{v} F :=
{ cocone := cocone_of_cone_left_op (limit.cone F.left_op),
is_colimit :=
{ desc := λ s, (limit.lift F.left_op (cone_left_op_of_cocone s)).op,
fac' := λ s j,
begin
rw [cocone_of_cone_left_op_ι_app, limit.cone_π, ←op_comp,
limit.lift_π, cone_left_op_of_cocone_π_app, has_hom.hom.op_unop],
refl, end,
uniq' := λ s m w,
begin
have u := (limit.is_limit F.left_op).uniq (cone_left_op_of_cocone s) (m.unop),
convert congr_arg (λ f : _ ⟶ _, f.op) (u _), clear u,
intro j,
rw [cone_left_op_of_cocone_π_app, limit.cone_π],
convert congr_arg (λ f : _ ⟶ _, f.unop) (w (unop j)), clear w,
rw [cocone_of_cone_left_op_ι_app, limit.cone_π, has_hom.hom.unop_op],
refl,
end } }
instance has_colimits_of_shape_op_of_has_limits_of_shape [has_limits_of_shape.{v} Jᵒᵖ C] :
has_colimits_of_shape.{v} J Cᵒᵖ :=
{ has_colimit := λ F, by apply_instance }
instance has_colimits_op_of_has_limits [has_limits.{v} C] : has_colimits.{v} Cᵒᵖ :=
{ has_colimits_of_shape := λ J 𝒥, by { resetI, apply_instance } }
variables (X : Type v)
instance has_coproducts_opposite [has_limits_of_shape (discrete X) C] :
has_colimits_of_shape (discrete X) Cᵒᵖ :=
begin
haveI : has_limits_of_shape (discrete X)ᵒᵖ C :=
has_limits_of_shape_of_equivalence (discrete.opposite X).symm, apply_instance
end
instance has_products_opposite [has_colimits_of_shape (discrete X) C] :
has_limits_of_shape (discrete X) Cᵒᵖ :=
begin
haveI : has_colimits_of_shape (discrete X)ᵒᵖ C :=
has_colimits_of_shape_of_equivalence (discrete.opposite X).symm, apply_instance
end
end category_theory.limits
|
c17a1f285668eb242d547312e36ff56f2d5d8ee1 | 57c233acf9386e610d99ed20ef139c5f97504ba3 | /src/order/monovary.lean | 01b3bb2930fa1567982e09163ec3072d37d4c58d | [
"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 | 8,741 | lean | /-
Copyright (c) 2021 Yaël Dillies. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies
-/
import order.monotone
/-!
# Monovariance of functions
Two functions *vary together* if a strict change in the first implies a change in the second.
This is in some sense a way to say that two functions `f : ι → α`, `g : ι → β` are "monotone
together", without actually having an order on `ι`.
This condition comes up in the rearrangement inequality. See `algebra.order.rearrangement`.
## Main declarations
* `monovary f g`: `f` monovaries with `g`. If `g i < g j`, then `f i ≤ f j`.
* `antivary f g`: `f` antivaries with `g`. If `g i < g j`, then `f j ≤ f i`.
* `monovary_on f g s`: `f` monovaries with `g` on `s`.
* `monovary_on f g s`: `f` antivaries with `g` on `s`.
-/
open function set
variables {ι ι' α β γ : Type*}
section preorder
variables [preorder α] [preorder β] {f : ι → α} {g : ι → β} {s t : set ι}
/-- `f` monovaries with `g` if `g i < g j` implies `f i ≤ f j`. -/
def monovary (f : ι → α) (g : ι → β) : Prop := ∀ ⦃i j⦄, g i < g j → f i ≤ f j
/-- `f` antivaries with `g` if `g i < g j` implies `f j ≤ f i`. -/
def antivary (f : ι → α) (g : ι → β) : Prop := ∀ ⦃i j⦄, g i < g j → f j ≤ f i
/-- `f` monovaries with `g` on `s` if `g i < g j` implies `f i ≤ f j` for all `i, j ∈ s`. -/
def monovary_on (f : ι → α) (g : ι → β) (s : set ι) : Prop :=
∀ ⦃i⦄ (hi : i ∈ s) ⦃j⦄ (hj : j ∈ s), g i < g j → f i ≤ f j
/-- `f` antivaries with `g` on `s` if `g i < g j` implies `f j ≤ f i` for all `i, j ∈ s`. -/
def antivary_on (f : ι → α) (g : ι → β) (s : set ι) : Prop :=
∀ ⦃i⦄ (hi : i ∈ s) ⦃j⦄ (hj : j ∈ s), g i < g j → f j ≤ f i
protected lemma monovary.monovary_on (h : monovary f g) (s : set ι) : monovary_on f g s :=
λ i j _ _ hij, h hij
protected lemma antivary.antivary_on (h : antivary f g) (s : set ι) : antivary_on f g s :=
λ i j _ _ hij, h hij
@[simp] lemma monovary_on_univ : monovary_on f g univ ↔ monovary f g :=
⟨λ h i j, h trivial trivial, λ h i j _ _ hij, h hij⟩
@[simp] lemma antivary_on_univ : antivary_on f g univ ↔ antivary f g :=
⟨λ h i j, h trivial trivial, λ h i j _ _ hij, h hij⟩
protected lemma monovary_on.subset (hst : s ⊆ t) (h : monovary_on f g t) : monovary_on f g s :=
λ i hi j hj, h (hst hi) (hst hj)
protected lemma antivary_on.subset (hst : s ⊆ t) (h : antivary_on f g t) : antivary_on f g s :=
λ i hi j hj, h (hst hi) (hst hj)
lemma monovary_const_left (g : ι → β) (a : α) : monovary (const ι a) g := λ i j _, le_rfl
lemma antivary_const_left (g : ι → β) (a : α) : antivary (const ι a) g := λ i j _, le_rfl
lemma monovary_const_right (f : ι → α) (b : β) : monovary f (const ι b) := λ i j h, (h.ne rfl).elim
lemma antivary_const_right (f : ι → α) (b : β) : antivary f (const ι b) := λ i j h, (h.ne rfl).elim
lemma monovary_self (f : ι → α) : monovary f f := λ i j, le_of_lt
lemma monovary_on_self (f : ι → α) (s : set ι) : monovary_on f f s := λ i j _ _, le_of_lt
lemma subsingleton.monovary [subsingleton ι] (f : ι → α) (g : ι → β) : monovary f g :=
λ i j h, (ne_of_apply_ne _ h.ne $ subsingleton.elim _ _).elim
lemma subsingleton.antivary [subsingleton ι] (f : ι → α) (g : ι → β) : antivary f g :=
λ i j h, (ne_of_apply_ne _ h.ne $ subsingleton.elim _ _).elim
lemma subsingleton.monovary_on [subsingleton ι] (f : ι → α) (g : ι → β) (s : set ι) :
monovary_on f g s :=
λ i j _ _ h, (ne_of_apply_ne _ h.ne $ subsingleton.elim _ _).elim
lemma subsingleton.antivary_on [subsingleton ι] (f : ι → α) (g : ι → β) (s : set ι) :
antivary_on f g s :=
λ i j _ _ h, (ne_of_apply_ne _ h.ne $ subsingleton.elim _ _).elim
lemma monovary_on_const_left (g : ι → β) (a : α) (s : set ι) : monovary_on (const ι a) g s :=
λ i j _ _ _, le_rfl
lemma antivary_on_const_left (g : ι → β) (a : α) (s : set ι) : antivary_on (const ι a) g s :=
λ i j _ _ _, le_rfl
lemma monovary_on_const_right (f : ι → α) (b : β) (s : set ι) : monovary_on f (const ι b) s :=
λ i j _ _ h, (h.ne rfl).elim
lemma antivary_on_const_right (f : ι → α) (b : β) (s : set ι) : antivary_on f (const ι b) s :=
λ i j _ _ h, (h.ne rfl).elim
lemma monovary.comp_right (h : monovary f g) (k : ι' → ι) : monovary (f ∘ k) (g ∘ k) :=
λ i j hij, h hij
lemma antivary.comp_right (h : antivary f g) (k : ι' → ι) : antivary (f ∘ k) (g ∘ k) :=
λ i j hij, h hij
section order_dual
open order_dual
lemma monovary.dual (h : monovary f g) : monovary (to_dual ∘ f) (to_dual ∘ g) := λ i j hij, h hij
lemma antivary.dual (h : antivary f g) : antivary (to_dual ∘ f) (to_dual ∘ g) := λ i j hij, h hij
lemma monovary.dual_left (h : monovary f g) : antivary (to_dual ∘ f) g := λ i j hij, h hij
lemma antivary.dual_left (h : antivary f g) : monovary (to_dual ∘ f) g := λ i j hij, h hij
lemma monovary.dual_right (h : monovary f g) : antivary f (to_dual ∘ g) := λ i j hij, h hij
lemma antivary.dual_right (h : antivary f g) : monovary f (to_dual ∘ g) := λ i j hij, h hij
lemma monovary_on.dual (h : monovary_on f g s) : monovary_on (to_dual ∘ f) (to_dual ∘ g) s :=
λ i hi j hj, h hj hi
lemma antivary_on.dual (h : antivary_on f g s) : antivary_on (to_dual ∘ f) (to_dual ∘ g) s :=
λ i hi j hj, h hj hi
lemma monovary_on.dual_left (h : monovary_on f g s) : antivary_on (to_dual ∘ f) g s := h
lemma antivary_on.dual_left (h : antivary_on f g s) : monovary_on (to_dual ∘ f) g s := h
lemma monovary_on.dual_right (h : monovary_on f g s) : antivary_on f (to_dual ∘ g) s := h.dual
lemma antivary_on.dual_right (h : antivary_on f g s) : monovary_on f (to_dual ∘ g) s := h.dual
end order_dual
section partial_order
variables [partial_order ι]
@[simp] lemma monovary_id_iff : monovary f id ↔ monotone f := monotone_iff_forall_lt.symm
@[simp] lemma antivary_id_iff : antivary f id ↔ antitone f := antitone_iff_forall_lt.symm
@[simp] lemma monovary_on_id_iff : monovary_on f id s ↔ monotone_on f s :=
monotone_on_iff_forall_lt.symm
@[simp] lemma antivary_on_id_iff : antivary_on f id s ↔ antitone_on f s :=
antitone_on_iff_forall_lt.symm
end partial_order
variables [linear_order ι]
protected lemma monotone.monovary (hf : monotone f) (hg : monotone g) : monovary f g :=
λ i j hij, hf (hg.reflect_lt hij).le
protected lemma monotone.antivary (hf : monotone f) (hg : antitone g) : antivary f g :=
(hf.monovary hg.dual_right).dual_right
protected lemma antitone.monovary (hf : antitone f) (hg : antitone g) : monovary f g :=
(hf.dual_right.antivary hg).dual_left
protected lemma antitone.antivary (hf : antitone f) (hg : monotone g) : antivary f g :=
(hf.monovary hg.dual_right).dual_right
protected lemma monotone_on.monovary_on (hf : monotone_on f s) (hg : monotone_on g s) :
monovary_on f g s :=
λ i hi j hj hij, hf hi hj (hg.reflect_lt hi hj hij).le
protected lemma monotone_on.antivary_on (hf : monotone_on f s) (hg : antitone_on g s) :
antivary_on f g s :=
(hf.monovary_on hg.dual_right).dual_right
protected lemma antitone_on.monovary_on (hf : antitone_on f s) (hg : antitone_on g s) :
monovary_on f g s :=
(hf.dual_right.antivary_on hg).dual_left
protected lemma antitone_on.antivary_on (hf : antitone_on f s) (hg : monotone_on g s) :
antivary_on f g s :=
(hf.monovary_on hg.dual_right).dual_right
end preorder
section linear_order
variables [preorder α] [linear_order β] {f : ι → α} {g : ι → β} {s :set ι}
protected lemma monovary.symm (h : monovary f g) : monovary g f :=
λ i j hf, le_of_not_lt $ λ hg, hf.not_le $ h hg
protected lemma antivary.symm (h : antivary f g) : antivary g f :=
λ i j hf, le_of_not_lt $ λ hg, hf.not_le $ h hg
protected lemma monovary_on.symm (h : monovary_on f g s) : monovary_on g f s :=
λ i hi j hj hf, le_of_not_lt $ λ hg, hf.not_le $ h hj hi hg
protected lemma antivary_on.symm (h : antivary_on f g s) : antivary_on g f s :=
λ i hi j hj hf, le_of_not_lt $ λ hg, hf.not_le $ h hi hj hg
end linear_order
section linear_order
variables [linear_order α] [linear_order β] {f : ι → α} {g : ι → β} {s : set ι}
protected lemma monovary_comm : monovary f g ↔ monovary g f := ⟨monovary.symm, monovary.symm⟩
protected lemma antivary_comm : antivary f g ↔ antivary g f := ⟨antivary.symm, antivary.symm⟩
protected lemma monovary_on_comm : monovary_on f g s ↔ monovary_on g f s :=
⟨monovary_on.symm, monovary_on.symm⟩
protected lemma antivary_on_comm : antivary_on f g s ↔ antivary_on g f s :=
⟨antivary_on.symm, antivary_on.symm⟩
end linear_order
|
667648d19131fd7995d3935f9a00b4f998e1acf5 | 32317185abf7e7c963f4c67c190aec61af6b3628 | /library/data/complex.lean | 491544041013565d6773689736ba6f5ba6c58017 | [
"Apache-2.0"
] | permissive | Andrew-Zipperer-unorganized/lean | 198a2317f21198cd8d26e7085e484b86277f17f7 | dcb35008e1474a0abebe632b1dced120e5f8c009 | refs/heads/master | 1,622,526,520,945 | 1,453,576,559,000 | 1,454,612,842,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 12,966 | lean | /-
Copyright (c) 2015 Jacob Gross. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jacob Gross, Jeremy Avigad
The complex numbers.
-/
import data.real
open real eq.ops
record complex : Type :=
(re : ℝ) (im : ℝ)
notation `ℂ` := complex
namespace complex
variables (u w z : ℂ)
variable n : ℕ
protected proposition eq {z w : ℂ} (H1 : complex.re z = complex.re w)
(H2 : complex.im z = complex.im w) : z = w :=
begin
induction z,
induction w,
rewrite [H1, H2]
end
protected proposition eta (z : ℂ) : complex.mk (complex.re z) (complex.im z) = z :=
by cases z; exact rfl
definition of_real [coercion] (x : ℝ) : ℂ := complex.mk x 0
definition of_rat [coercion] (q : ℚ) : ℂ := rat.to.complex q
definition of_int [coercion] (i : ℤ) : ℂ := int.to.complex i
definition of_nat [coercion] (n : ℕ) : ℂ := nat.to.complex n
definition of_num [coercion] [reducible] (n : num) : ℂ := num.to.complex n
protected definition prio : num := num.pred real.prio
definition complex_has_zero [reducible] [instance] [priority complex.prio] : has_zero ℂ :=
has_zero.mk (of_nat 0)
definition complex_has_one [reducible] [instance] [priority complex.prio] : has_one ℂ :=
has_one.mk (of_nat 1)
theorem re_of_real (x : ℝ) : re (of_real x) = x := rfl
theorem im_of_real (x : ℝ) : im (of_real x) = 0 := rfl
protected definition add (z w : ℂ) : ℂ :=
complex.mk (complex.re z + complex.re w) (complex.im z + complex.im w)
protected definition neg (z : ℂ) : ℂ :=
complex.mk (-(re z)) (-(im z))
protected definition mul (z w : ℂ) : ℂ :=
complex.mk
(complex.re w * complex.re z - complex.im w * complex.im z)
(complex.re w * complex.im z + complex.im w * complex.re z)
/- notation -/
definition complex_has_add [reducible] [instance] [priority complex.prio] : has_add complex :=
has_add.mk complex.add
definition complex_has_neg [reducible] [instance] [priority complex.prio] : has_neg complex :=
has_neg.mk complex.neg
definition complex_has_mul [reducible] [instance] [priority complex.prio] : has_mul complex :=
has_mul.mk complex.mul
protected theorem add_def (z w : ℂ) :
z + w = complex.mk (complex.re z + complex.re w) (complex.im z + complex.im w) := rfl
protected theorem neg_def (z : ℂ) : -z = complex.mk (-(re z)) (-(im z)) := rfl
protected theorem mul_def (z w : ℂ) :
z * w = complex.mk
(complex.re w * complex.re z - complex.im w * complex.im z)
(complex.re w * complex.im z + complex.im w * complex.re z) := rfl
-- TODO: what notation should we use for i?
definition ii := complex.mk 0 1
theorem i_mul_i : ii * ii = -1 := rfl
/- basic properties -/
protected theorem add_comm (w z : ℂ) : w + z = z + w :=
complex.eq !add.comm !add.comm
protected theorem add_assoc (w z u : ℂ) : (w + z) + u = w + (z + u) :=
complex.eq !add.assoc !add.assoc
protected theorem add_zero (z : ℂ) : z + 0 = z :=
complex.eq !add_zero !add_zero
protected theorem zero_add (z : ℂ) : 0 + z = z := !complex.add_comm ▸ !complex.add_zero
definition smul (x : ℝ) (z : ℂ) : ℂ :=
complex.mk (x*re z) (x*im z)
protected theorem add_right_inv : z + - z = 0 :=
complex.eq !add.right_inv !add.right_inv
protected theorem add_left_inv : - z + z = 0 :=
!complex.add_comm ▸ !complex.add_right_inv
protected theorem mul_comm : w * z = z * w :=
by rewrite [*complex.mul_def, *mul.comm (re w), *mul.comm (im w), add.comm]
protected theorem one_mul : 1 * z = z :=
by krewrite [complex.mul_def, *mul_one, *mul_zero, sub_zero, zero_add, complex.eta]
protected theorem mul_one : z * 1 = z := !complex.mul_comm ▸ !complex.one_mul
protected theorem left_distrib : u * (w + z) = u * w + u * z :=
begin
rewrite [*complex.mul_def, *complex.add_def, ▸*, *right_distrib, -sub_sub, *sub_eq_add_neg],
rewrite [*add.assoc, add.left_comm (re z * im u), add.left_comm (-_)]
end
protected theorem right_distrib : (u + w) * z = u * z + w * z :=
by rewrite [*complex.mul_comm _ z, complex.left_distrib]
protected theorem mul_assoc : (u * w) * z = u * (w * z) :=
begin
rewrite [*complex.mul_def, ▸*, *sub_eq_add_neg, *left_distrib, *right_distrib, *neg_add],
rewrite [-*neg_mul_eq_neg_mul, -*neg_mul_eq_mul_neg, *add.assoc, *mul.assoc],
rewrite [add.comm (-(im z * (im w * _))), add.comm (-(im z * (im w * _))), *add.assoc]
end
theorem re_add (z w : ℂ) : re (z + w) = re z + re w := rfl
theorem im_add (z w : ℂ) : im (z + w) = im z + im w := rfl
/- coercions -/
theorem of_real_add (a b : ℝ) : of_real (a + b) = of_real a + of_real b := rfl
theorem of_real_mul (a b : ℝ) : of_real (a * b) = (of_real a) * (of_real b) :=
by rewrite [complex.mul_def, *re_of_real, *im_of_real, *mul_zero, *zero_mul, sub_zero, add_zero,
mul.comm]
theorem of_real_neg (a : ℝ) : of_real (-a) = -(of_real a) := rfl
theorem of_real.inj {a b : ℝ} (H : of_real a = of_real b) : a = b :=
show re (of_real a) = re (of_real b), from congr_arg re H
theorem eq_of_of_real_eq_of_real {a b : ℝ} (H : of_real a = of_real b) : a = b :=
of_real.inj H
theorem of_real_eq_of_real_iff (a b : ℝ) : of_real a = of_real b ↔ a = b :=
iff.intro eq_of_of_real_eq_of_real !congr_arg
/- make complex an instance of ring -/
protected definition comm_ring [reducible] : comm_ring complex :=
begin
fapply comm_ring.mk,
exact complex.add,
exact complex.add_assoc,
exact 0,
exact complex.zero_add,
exact complex.add_zero,
exact complex.neg,
exact complex.add_left_inv,
exact complex.add_comm,
exact complex.mul,
exact complex.mul_assoc,
exact 1,
apply complex.one_mul,
apply complex.mul_one,
apply complex.left_distrib,
apply complex.right_distrib,
apply complex.mul_comm
end
local attribute complex.comm_ring [instance]
definition complex_has_sub [reducible] [instance] [priority complex.prio] : has_sub complex :=
has_sub.mk has_sub.sub
theorem of_real_sub (x y : ℝ) : of_real (x - y) = of_real x - of_real y :=
rfl
-- TODO: move these
private lemma eq_zero_of_mul_self_eq_zero {x : ℝ} (H : x * x = 0) : x = 0 :=
iff.mp !or_self (!eq_zero_or_eq_zero_of_mul_eq_zero H)
private lemma eq_zero_of_sum_square_eq_zero {x y : ℝ} (H : x * x + y * y = 0) : x = 0 :=
have x * x ≤ (0 : ℝ), 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))
/- complex modulus and conjugate-/
definition cmod (z : ℂ) : ℝ :=
(complex.re z) * (complex.re z) + (complex.im z) * (complex.im z)
theorem cmod_zero : cmod 0 = 0 := rfl
theorem cmod_of_real (x : ℝ) : cmod x = x * x :=
by rewrite [↑cmod, re_of_real, im_of_real, mul_zero, add_zero]
theorem eq_zero_of_cmod_eq_zero {z : ℂ} (H : cmod z = 0) : z = 0 :=
have H1 : (complex.re z) * (complex.re z) + (complex.im z) * (complex.im z) = 0,
from H,
have H2 : complex.re z = 0, from eq_zero_of_sum_square_eq_zero H1,
have H3 : complex.im z = 0, from eq_zero_of_sum_square_eq_zero (!add.comm ▸ H1),
show z = 0, from complex.eq H2 H3
definition conj (z : ℂ) : ℂ := complex.mk (complex.re z) (-(complex.im z))
theorem conj_of_real {x : ℝ} : conj (of_real x) = of_real x := rfl
theorem conj_add (z w : ℂ) : conj (z + w) = conj z + conj w :=
by rewrite [↑conj, *complex.add_def, ▸*, neg_add]
theorem conj_mul (z w : ℂ) : conj (z * w) = conj z * conj w :=
by rewrite [↑conj, *complex.mul_def, ▸*, neg_mul_neg, neg_add,
-neg_mul_eq_mul_neg, -neg_mul_eq_neg_mul]
theorem conj_conj (z : ℂ) : conj (conj z) = z :=
by rewrite [↑conj, neg_neg, complex.eta]
theorem mul_conj_eq_of_real_cmod (z : ℂ) : z * conj z = of_real (cmod z) :=
by rewrite [↑conj, ↑cmod, ↑of_real, complex.mul_def, ▸*, -*neg_mul_eq_neg_mul,
sub_neg_eq_add, mul.comm (re z) (im z), add.right_inv]
theorem cmod_conj (z : ℂ) : cmod (conj z) = cmod z :=
begin
apply eq_of_of_real_eq_of_real,
rewrite [-*mul_conj_eq_of_real_cmod, conj_conj, mul.comm]
end
theorem cmod_mul (z w : ℂ) : cmod (z * w) = cmod z * cmod w :=
begin
apply eq_of_of_real_eq_of_real,
rewrite [of_real_mul, -*mul_conj_eq_of_real_cmod, conj_mul, *mul.assoc, mul.left_comm w]
end
protected noncomputable definition inv (z : ℂ) : complex := conj z * of_real (cmod z)⁻¹
protected noncomputable definition complex_has_inv [reducible] [instance] [priority complex.prio] :
has_inv complex := has_inv.mk complex.inv
protected theorem inv_def (z : ℂ) : z⁻¹ = conj z * of_real (cmod z)⁻¹ := rfl
protected theorem inv_zero : 0⁻¹ = (0 : ℂ) :=
by krewrite [complex.inv_def, conj_of_real, zero_mul]
theorem of_real_inv (x : ℝ) : of_real x⁻¹ = (of_real x)⁻¹ :=
classical.by_cases
(assume H : x = 0,
by krewrite [H, inv_zero, complex.inv_zero])
(assume H : x ≠ 0,
by rewrite [complex.inv_def, cmod_of_real, conj_of_real, mul_inv_eq H H, -of_real_mul,
-mul.assoc, mul_inv_cancel H, one_mul])
noncomputable protected definition div (z w : ℂ) : ℂ := z * w⁻¹
noncomputable definition complex_has_div [instance] [reducible] [priority complex.prio] :
has_div complex :=
has_div.mk complex.div
protected theorem div_def (z w : ℂ) : z / w = z * w⁻¹ := rfl
theorem of_real_div (x y : ℝ) : of_real (x / y) = of_real x / of_real y :=
have H : x / y = x * y⁻¹, from rfl,
by+ rewrite [H, complex.div_def, of_real_mul, of_real_inv]
theorem conj_inv (z : ℂ) : (conj z)⁻¹ = conj (z⁻¹) :=
by rewrite [*complex.inv_def, conj_mul, *conj_conj, conj_of_real, cmod_conj]
protected theorem mul_inv_cancel {z : ℂ} (H : z ≠ 0) : z * z⁻¹ = 1 :=
by rewrite [complex.inv_def, -mul.assoc, mul_conj_eq_of_real_cmod, -of_real_mul,
mul_inv_cancel (assume H', H (eq_zero_of_cmod_eq_zero H'))]
protected theorem inv_mul_cancel {z : ℂ} (H : z ≠ 0) : z⁻¹ * z = 1 :=
!mul.comm ▸ complex.mul_inv_cancel H
protected noncomputable definition has_decidable_eq : decidable_eq ℂ :=
take z w, classical.prop_decidable (z = w)
protected theorem zero_ne_one : (0 : ℂ) ≠ 1 :=
assume H, zero_ne_one (eq_of_of_real_eq_of_real H)
protected noncomputable definition discrete_field [reducible][trans_instance] :
discrete_field ℂ :=
⦃ discrete_field, complex.comm_ring,
mul_inv_cancel := @complex.mul_inv_cancel,
inv_mul_cancel := @complex.inv_mul_cancel,
zero_ne_one := complex.zero_ne_one,
inv_zero := complex.inv_zero,
has_decidable_eq := complex.has_decidable_eq
⦄
-- TODO : we still need the whole family of coercion properties, for nat, int, rat
-- coercions
theorem of_rat_eq (a : ℚ) : of_rat a = of_real (real.of_rat a) := rfl
theorem of_int_eq (a : ℤ) : of_int a = of_real (real.of_int a) := rfl
theorem of_nat_eq (a : ℕ) : of_nat a = of_real (real.of_nat a) := rfl
theorem of_rat.inj {x y : ℚ} (H : of_rat x = of_rat y) : x = y :=
real.of_rat.inj (of_real.inj H)
theorem eq_of_of_rat_eq_of_rat {x y : ℚ} (H : of_rat x = of_rat y) : x = y :=
of_rat.inj H
theorem of_rat_eq_of_rat_iff (x y : ℚ) : of_rat x = of_rat y ↔ x = y :=
iff.intro eq_of_of_rat_eq_of_rat !congr_arg
theorem of_int.inj {a b : ℤ} (H : of_int a = of_int b) : a = b :=
rat.of_int.inj (of_rat.inj H)
theorem eq_of_of_int_eq_of_int {a b : ℤ} (H : of_int a = of_int b) : a = b :=
of_int.inj H
theorem of_int_eq_of_int_iff (a b : ℤ) : of_int a = of_int b ↔ a = b :=
iff.intro of_int.inj !congr_arg
theorem of_nat.inj {a b : ℕ} (H : of_nat a = of_nat b) : a = b :=
int.of_nat.inj (of_int.inj H)
theorem eq_of_of_nat_eq_of_nat {a b : ℕ} (H : of_nat a = of_nat b) : a = b :=
of_nat.inj H
theorem of_nat_eq_of_nat_iff (a b : ℕ) : of_nat a = of_nat b ↔ a = b :=
iff.intro of_nat.inj !congr_arg
open rat
theorem of_rat_add (a b : ℚ) : of_rat (a + b) = of_rat a + of_rat b :=
by rewrite [of_rat_eq]
theorem of_rat_neg (a : ℚ) : of_rat (-a) = -of_rat a :=
by rewrite [of_rat_eq]
-- these show why we have to use krewrite in the next theorem: there are
-- two different instances of "has_mul".
-- set_option pp.notation false
-- set_option pp.coercions true
-- set_option pp.implicit true
theorem of_rat_mul (a b : ℚ) : of_rat (a * b) = of_rat a * of_rat b :=
by krewrite [of_rat_eq, real.of_rat_mul, of_real_mul]
open int
theorem of_int_add (a b : ℤ) : of_int (a + b) = of_int a + of_int b :=
by krewrite [of_int_eq, real.of_int_add, of_real_add]
theorem of_int_neg (a : ℤ) : of_int (-a) = -of_int a :=
by krewrite [of_int_eq, real.of_int_neg, of_real_neg]
theorem of_int_mul (a b : ℤ) : of_int (a * b) = of_int a * of_int b :=
by krewrite [of_int_eq, real.of_int_mul, of_real_mul]
open nat
theorem of_nat_add (a b : ℕ) : of_nat (a + b) = of_nat a + of_nat b :=
by krewrite [of_nat_eq, real.of_nat_add, of_real_add]
theorem of_nat_mul (a b : ℕ) : of_nat (a * b) = of_nat a * of_nat b :=
by krewrite [of_nat_eq, real.of_nat_mul, of_real_mul]
end complex
|
302183b2e00b47863da4839f7d2b6d79cada114c | 5d166a16ae129621cb54ca9dde86c275d7d2b483 | /library/init/function.lean | 985ed189ca37597fef8f71eda503fc050fd3c898 | [
"Apache-2.0"
] | permissive | jcarlson23/lean | b00098763291397e0ac76b37a2dd96bc013bd247 | 8de88701247f54d325edd46c0eed57aeacb64baf | refs/heads/master | 1,611,571,813,719 | 1,497,020,963,000 | 1,497,021,515,000 | 93,882,536 | 1 | 0 | null | 1,497,029,896,000 | 1,497,029,896,000 | null | UTF-8 | Lean | false | false | 5,382 | lean | /-
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura, Jeremy Avigad, Haitao Zhang
General operations on functions.
-/
prelude
import init.data.prod init.funext init.logic
universes u₁ u₂ u₃ u₄
namespace function
variables {α : Sort u₁} {β : Sort u₂} {φ : Sort u₃} {δ : Sort u₄} {ζ : Sort u₁}
@[inline, reducible] def comp (f : β → φ) (g : α → β) : α → φ :=
λ x, f (g x)
@[inline, reducible] def dcomp {β : α → Sort u₂} {φ : Π {x : α}, β x → Sort u₃}
(f : Π {x : α} (y : β x), φ y) (g : Π x, β x) : Π x, φ (g x) :=
λ x, f (g x)
infixr ` ∘ ` := function.comp
infixr ` ∘' `:80 := function.dcomp
@[reducible] def comp_right (f : β → β → β) (g : α → β) : β → α → β :=
λ b a, f b (g a)
@[reducible] def comp_left (f : β → β → β) (g : α → β) : α → β → β :=
λ a b, f (g a) b
@[reducible] def on_fun (f : β → β → φ) (g : α → β) : α → α → φ :=
λ x y, f (g x) (g y)
@[reducible] def combine (f : α → β → φ) (op : φ → δ → ζ) (g : α → β → δ)
: α → β → ζ :=
λ x y, op (f x y) (g x y)
@[reducible] def const (β : Sort u₂) (a : α) : β → α :=
λ x, a
@[reducible] def swap {φ : α → β → Sort u₃} (f : Π x y, φ x y) : Π y x, φ x y :=
λ y x, f x y
@[reducible] def app {β : α → Sort u₂} (f : Π x, β x) (x : α) : β x :=
f x
infixl ` on `:2 := on_fun
notation f ` -[` op `]- ` g := combine f op g
lemma left_id (f : α → β) : id ∘ f = f := rfl
lemma right_id (f : α → β) : f ∘ id = f := rfl
lemma comp.assoc (f : φ → δ) (g : β → φ) (h : α → β) : (f ∘ g) ∘ h = f ∘ (g ∘ h) := rfl
lemma comp.left_id (f : α → β) : id ∘ f = f := rfl
lemma comp.right_id (f : α → β) : f ∘ id = f := rfl
lemma comp_const_right (f : β → φ) (b : β) : f ∘ (const α b) = const α (f b) := rfl
@[reducible] def injective (f : α → β) : Prop := ∀ ⦃a₁ a₂⦄, f a₁ = f a₂ → a₁ = a₂
lemma injective_comp {g : β → φ} {f : α → β} (hg : injective g) (hf : injective f) : injective (g ∘ f) :=
take a₁ a₂, assume h, hf (hg h)
@[reducible] def surjective (f : α → β) : Prop := ∀ b, ∃ a, f a = b
lemma surjective_comp {g : β → φ} {f : α → β} (hg : surjective g) (hf : surjective f) : surjective (g ∘ f) :=
λ (c : φ), exists.elim (hg c) (λ b hb, exists.elim (hf b) (λ a ha,
exists.intro a (show g (f a) = c, from (eq.trans (congr_arg g ha) hb))))
def bijective (f : α → β) := injective f ∧ surjective f
lemma bijective_comp {g : β → φ} {f : α → β} : bijective g → bijective f → bijective (g ∘ f)
| ⟨h_ginj, h_gsurj⟩ ⟨h_finj, h_fsurj⟩ := ⟨injective_comp h_ginj h_finj, surjective_comp h_gsurj h_fsurj⟩
-- g is a left inverse to f
def left_inverse (g : β → α) (f : α → β) : Prop := ∀ x, g (f x) = x
def has_left_inverse (f : α → β) : Prop := ∃ finv : β → α, left_inverse finv f
-- g is a right inverse to f
def right_inverse (g : β → α) (f : α → β) : Prop := left_inverse f g
def has_right_inverse (f : α → β) : Prop := ∃ finv : β → α, right_inverse finv f
lemma injective_of_left_inverse {g : β → α} {f : α → β} : left_inverse g f → injective f :=
assume h, take a b, assume faeqfb,
have h₁ : a = g (f a), from eq.symm (h a),
have h₂ : g (f b) = b, from h b,
have h₃ : g (f a) = g (f b), from congr_arg g faeqfb,
eq.trans h₁ (eq.trans h₃ h₂)
lemma injective_of_has_left_inverse {f : α → β} : has_left_inverse f → injective f :=
assume h, exists.elim h (λ finv inv, injective_of_left_inverse inv)
lemma right_inverse_of_injective_of_left_inverse {f : α → β} {g : β → α}
(injf : injective f) (lfg : left_inverse f g) :
right_inverse f g :=
take x,
have h : f (g (f x)) = f x, from lfg (f x),
injf h
lemma surjective_of_has_right_inverse {f : α → β} : has_right_inverse f → surjective f
| ⟨finv, inv⟩ b := ⟨finv b, inv b⟩
lemma left_inverse_of_surjective_of_right_inverse {f : α → β} {g : β → α}
(surjf : surjective f) (rfg : right_inverse f g) :
left_inverse f g :=
take y, exists.elim (surjf y) (λ x hx, calc
f (g y) = f (g (f x)) : hx ▸ rfl
... = f x : eq.symm (rfg x) ▸ rfl
... = y : hx)
lemma injective_id : injective (@id α) := take a₁ a₂ h, h
lemma surjective_id : surjective (@id α) := take a, ⟨a, rfl⟩
lemma bijective_id : bijective (@id α) := ⟨injective_id, surjective_id⟩
end function
namespace function
variables {α : Type u₁} {β : Type u₂} {φ : Type u₃}
@[inline] def curry : (α × β → φ) → α → β → φ :=
λ f a b, f (a, b)
@[inline] def uncurry : (α → β → φ) → α × β → φ :=
λ f ⟨a, b⟩, f a b
@[simp] lemma curry_uncurry (f : α → β → φ) : curry (uncurry f) = f :=
rfl
@[simp] lemma uncurry_curry (f : α × β → φ) : uncurry (curry f) = f :=
funext (λ ⟨a, b⟩, rfl)
def id_of_left_inverse {g : β → α} {f : α → β} : left_inverse g f → g ∘ f = id :=
assume h, funext h
def id_of_right_inverse {g : β → α} {f : α → β} : right_inverse g f → f ∘ g = id :=
assume h, funext h
end function
|
9bbef9928332bcd2e2bd49216a7c58d6bbcabeab | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/tactic/generalizes.lean | 22078e8c3e851275ce1d1facd28e76eb0fe061dd | [] | 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 | 4,973 | 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 Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.tactic.core
import Mathlib.PostPort
namespace Mathlib
/-!
# The `generalizes` tactic
This module defines the `tactic.generalizes'` tactic and its interactive version
`tactic.interactive.generalizes`. These work like `generalize`, but they can
generalize over multiple expressions at once. This is particularly handy when
there are dependencies between the expressions, in which case `generalize` will
usually fail but `generalizes` may succeed.
## Implementation notes
To generalize the target `T` over expressions `j₁ : J₁, ..., jₙ : Jₙ`, we first
create the new target type
T' = ∀ (k₁ : J₁) ... (kₙ : Jₙ) (k₁_eq : k₁ = j₁) ... (kₙ_eq : kₙ == jₙ), U
where `U` is `T` with any occurrences of the `jᵢ` replaced by the corresponding
`kᵢ`. Note that some of the `kᵢ_eq` may be heterogeneous; this happens when
there are dependencies between the `jᵢ`. The construction of `T'` is performed
by `generalizes.step1` and `generalizes.step2`.
Having constructed `T'`, we can `assert` it and use it to construct a proof of
the original target by instantiating the binders with
j₁ ... jₙ (eq.refl j₁) ... (heq.refl jₙ).
This leaves us with a generalized goal. This construction is performed by
`generalizes.step3`.
-/
namespace tactic
namespace generalizes
/--
Input:
- Target expression `e`.
- List of expressions `jᵢ` to be generalised, along with a name for the local
const that will replace them. The `jᵢ` must be in dependency order:
`[n, fin n]` is okay but `[fin n, n]` is not.
Output:
- List of new local constants `kᵢ`, one for each `jᵢ`.
- `e` with the `jᵢ` replaced by the `kᵢ`, i.e. `e[jᵢ := kᵢ]...[j₀ := k₀]`.
Note that the substitution also affects the types of the `kᵢ`: If `jᵢ : Jᵢ` then
`kᵢ : Jᵢ[jᵢ₋₁ := kᵢ₋₁]...[j₀ := k₀]`.
The transparency `md` and the boolean `unify` are passed to `kabstract` when we
abstract over occurrences of the `jᵢ` in `e`.
-/
/--
Input: for each equation that should be generated: the equation name, the
argument `jᵢ` and the corresponding local constant `kᵢ` from step 1.
Output: for each element of the input list a new local constant of type
`jᵢ = kᵢ` or `jᵢ == kᵢ` and a proof of `jᵢ = jᵢ` or `jᵢ == jᵢ`.
The transparency `md` is used when determining whether the type of `jᵢ` is defeq
to the type of `kᵢ` (and thus whether to generate a homogeneous or heterogeneous
equation).
-/
/--
Input: The `jᵢ`; the local constants `kᵢ` from step 1; the equations and their
proofs from step 2.
This step is the first one that changes the goal (and also the last one
overall). It asserts the generalized goal, then derives the current goal from
it. This leaves us with the generalized goal.
-/
end generalizes
/--
Generalizes the target over each of the expressions in `args`. Given
`args = [(a₁, h₁, arg₁), ...]`, this changes the target to
∀ (a₁ : T₁) ... (h₁ : a₁ = arg₁) ..., U
where `U` is the current target with every occurrence of `argᵢ` replaced by
`aᵢ`. A similar effect can be achieved by using `generalize` once for each of
the `args`, but if there are dependencies between the `args`, this may fail to
perform some generalizations.
The replacement is performed using keyed matching/unification with transparency
`md`. `unify` determines whether matching or unification is used. See
`kabstract`.
The `args` must be given in dependency order, so `[n, fin n]` is okay but
`[fin n, n]` will result in an error.
After generalizing the `args`, the target type may no longer type check.
`generalizes'` will then raise an error.
-/
/--
Like `generalizes'`, but also introduces the generalized constants and their
associated equations into the context.
-/
namespace interactive
/--
Generalizes the target over multiple expressions. For example, given the goal
P : ∀ n, fin n → Prop
n : ℕ
f : fin n
⊢ P (nat.succ n) (fin.succ f)
you can use `generalizes [n'_eq : nat.succ n = n', f'_eq : fin.succ f == f']` to
get
P : ∀ n, fin n → Prop
n : ℕ
f : fin n
n' : ℕ
n'_eq : n' = nat.succ n
f' : fin n'
f'_eq : f' == fin.succ f
⊢ P n' f'
The expressions must be given in dependency order, so
`[f'_eq : fin.succ f == f', n'_eq : nat.succ n = n']` would fail since the type
of `fin.succ f` is `nat.succ n`.
You can choose to omit some or all of the generated equations. For the above
example, `generalizes [nat.succ n = n', fin.succ f == f']` gets you
P : ∀ n, fin n → Prop
n : ℕ
f : fin n
n' : ℕ
f' : fin n'
⊢ P n' f'
After generalization, the target type may no longer type check. `generalizes`
will then raise an error.
-/
|
b2c9e65767c978662f61de83a0a5c2743846d229 | b7f22e51856f4989b970961f794f1c435f9b8f78 | /tests/lean/simplifier10.lean | fe47ccc65452c9298c3166be053df1bdf3dd84a5 | [
"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 | 529 | lean | import logic.connectives logic.quantifiers
universe l
constants (T : Type.{l}) (x y z : T) (P : T → Prop) (Q : T → T → T → Prop) (R W V : T → T → Prop)
constants (px : P x) (wxz : W x z) (vzy : V z y)
constants (H : ∀ (x y z : T), P x → W x z → V z y → (Q z y x ↔ R x y))
attribute px true_iff [simp]
attribute wxz [simp]
attribute vzy [simp]
attribute H [simp]
#simplify iff env 0 P x
#simplify iff env 0 W x z
#simplify iff env 0 V z y
#simplify iff env 0 Q z y x
#simplify iff env 0 V z y ↔ Q z y x
|
68a2aa11a0b14607adbf132a0f25fd663b2044a6 | 853df553b1d6ca524e3f0a79aedd32dde5d27ec3 | /src/measure_theory/l1_space.lean | 761f569515e6372d9a884bb89abfad65b840ca75 | [
"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 | 28,595 | lean | /-
Copyright (c) 2019 Zhouhang Zhou. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Zhouhang Zhou
-/
import measure_theory.ae_eq_fun
/-!
# Integrable functions and `L¹` space
In the first part of this file, the predicate `integrable` is defined and basic properties of
integrable functions are proved.
In the second part, the space `L¹` of equivalence classes of integrable functions under the relation
of being almost everywhere equal is defined as a subspace of the space `L⁰`. See the file
`src/measure_theory/ae_eq_fun.lean` for information on `L⁰` space.
## Notation
* `α →₁ β` is the type of `L¹` space, where `α` is a `measure_space` and `β` is a `normed_group`
with a `second_countable_topology`. `f : α →ₘ β` is a "function" in `L¹`. In comments, `[f]` is
also used to denote an `L¹` function.
`₁` can be typed as `\1`.
## Main definitions
* Let `f : α → β` be a function, where `α` is a `measure_space` and `β` a `normed_group`.
Then `f` is called `integrable` if `(∫⁻ a, nnnorm (f a)) < ⊤` holds.
* The space `L¹` is defined as a subspace of `L⁰` :
An `ae_eq_fun` `[f] : α →ₘ β` is in the space `L¹` if `edist [f] 0 < ⊤`, which means
`(∫⁻ a, edist (f a) 0) < ⊤` if we expand the definition of `edist` in `L⁰`.
## Main statements
`L¹`, as a subspace, inherits most of the structures of `L⁰`.
## Implementation notes
Maybe `integrable f` should be mean `(∫⁻ a, edist (f a) 0) < ⊤`, so that `integrable` and
`ae_eq_fun.integrable` are more aligned. But in the end one can use the lemma
`lintegral_nnnorm_eq_lintegral_edist : (∫⁻ a, nnnorm (f a)) = (∫⁻ a, edist (f a) 0)` to switch the
two forms.
## Tags
integrable, function space, l1
-/
noncomputable theory
open_locale classical topological_space
namespace measure_theory
open set filter topological_space ennreal emetric
open_locale big_operators
universes u v w
variables {α : Type u} [measure_space α]
variables {β : Type v} [normed_group β] {γ : Type w} [normed_group γ]
/-- A function is `integrable` if the integral of its pointwise norm is less than infinity. -/
def integrable (f : α → β) : Prop := (∫⁻ a, nnnorm (f a)) < ⊤
lemma integrable_iff_norm (f : α → β) : integrable f ↔ (∫⁻ a, ennreal.of_real ∥f a∥) < ⊤ :=
by simp only [integrable, of_real_norm_eq_coe_nnnorm]
lemma integrable_iff_edist (f : α → β) : integrable f ↔ (∫⁻ a, edist (f a) 0) < ⊤ :=
have eq : (λa, edist (f a) 0) = (λa, (nnnorm(f a) : ennreal)),
by { funext, rw edist_eq_coe_nnnorm },
iff.intro (by { rw eq, exact λh, h }) $ by { rw eq, exact λh, h }
lemma integrable_iff_of_real {f : α → ℝ} (h : ∀ₘ a, 0 ≤ f a) :
integrable f ↔ (∫⁻ a, ennreal.of_real (f a)) < ⊤ :=
have lintegral_eq : (∫⁻ a, ennreal.of_real ∥f a∥) = (∫⁻ a, ennreal.of_real (f a)) :=
begin
apply lintegral_congr_ae,
filter_upwards [h],
simp only [mem_set_of_eq],
assume a h,
rw [real.norm_eq_abs, abs_of_nonneg],
exact h
end,
by rw [integrable_iff_norm, lintegral_eq]
lemma integrable_of_ae_eq {f g : α → β} (hf : integrable f) (h : ∀ₘ a, f a = g a) : integrable g :=
begin
simp only [integrable] at *,
have : (∫⁻ (a : α), ↑(nnnorm (f a))) = (∫⁻ (a : α), ↑(nnnorm (g a))),
{ apply lintegral_congr_ae,
filter_upwards [h],
assume a,
simp only [mem_set_of_eq],
assume h,
rw h },
rwa ← this
end
lemma integrable_congr_ae {f g : α → β} (h : ∀ₘ a, f a = g a) : integrable f ↔ integrable g :=
iff.intro (λhf, integrable_of_ae_eq hf h) (λhg, integrable_of_ae_eq hg (ae_eq_symm h))
lemma integrable_of_le_ae {f : α → β} {g : α → γ} (h : ∀ₘ a, ∥f a∥ ≤ ∥g a∥) (hg : integrable g) :
integrable f :=
begin
simp only [integrable_iff_norm] at *,
calc (∫⁻ a, ennreal.of_real ∥f a∥) ≤ (∫⁻ (a : α), ennreal.of_real ∥g a∥) :
lintegral_le_lintegral_ae (by { filter_upwards [h], assume a h, exact of_real_le_of_real h })
... < ⊤ : hg
end
lemma integrable_of_le {f : α → β} {g : α → γ} (h : ∀a, ∥f a∥ ≤ ∥g a∥) (hg : integrable g) :
integrable f :=
integrable_of_le_ae (ae_of_all _ h) hg
lemma lintegral_nnnorm_eq_lintegral_edist (f : α → β) :
(∫⁻ a, nnnorm (f a)) = ∫⁻ a, edist (f a) 0 :=
by simp only [edist_eq_coe_nnnorm]
lemma lintegral_norm_eq_lintegral_edist (f : α → β) :
(∫⁻ a, ennreal.of_real ∥f a∥) = ∫⁻ a, edist (f a) 0 :=
by simp only [of_real_norm_eq_coe_nnnorm, edist_eq_coe_nnnorm]
lemma lintegral_edist_triangle [second_countable_topology β] [measurable_space β]
[opens_measurable_space β] {f g h : α → β}
(hf : measurable f) (hg : measurable g) (hh : measurable h) :
(∫⁻ a, edist (f a) (g a)) ≤ (∫⁻ a, edist (f a) (h a)) + ∫⁻ a, edist (g a) (h a) :=
begin
rw ← lintegral_add (hf.edist hh) (hg.edist hh),
apply lintegral_mono,
assume a,
have := edist_triangle (f a) (h a) (g a),
convert this,
rw edist_comm (h a) (g a),
end
lemma lintegral_edist_lt_top [second_countable_topology β] [measurable_space β]
[opens_measurable_space β] {f g : α → β}
(hfm : measurable f) (hfi : integrable f) (hgm : measurable g) (hgi : integrable g) :
(∫⁻ a, edist (f a) (g a)) < ⊤ :=
lt_of_le_of_lt
(lintegral_edist_triangle hfm hgm (measurable_const : measurable (λa, (0 : β))))
(ennreal.add_lt_top.2 $ by { split; rw ← integrable_iff_edist; assumption })
lemma lintegral_nnnorm_zero : (∫⁻ a : α, nnnorm (0 : β)) = 0 := by simp
variables (α β)
@[simp] lemma integrable_zero : integrable (λa:α, (0:β)) :=
by simp [integrable]
variables {α β}
lemma lintegral_nnnorm_add [measurable_space β] [opens_measurable_space β]
[measurable_space γ] [opens_measurable_space γ]
{f : α → β} {g : α → γ} (hf : measurable f) (hg : measurable g) :
(∫⁻ a, nnnorm (f a) + nnnorm (g a)) = (∫⁻ a, nnnorm (f a)) + ∫⁻ a, nnnorm (g a) :=
lintegral_add hf.ennnorm hg.ennnorm
lemma integrable.add [measurable_space β] [opens_measurable_space β]
{f g : α → β} (hfm : measurable f) (hfi : integrable f)
(hgm : measurable g) (hgi : integrable g) :
integrable (λa, f a + g a) :=
calc
(∫⁻ (a : α), ↑(nnnorm ((f + g) a))) ≤ ∫⁻ (a : α), ↑(nnnorm (f a)) + ↑(nnnorm (g a)) :
lintegral_mono
(assume a, by { simp only [← coe_add, coe_le_coe], exact nnnorm_add_le _ _ })
... = _ :
lintegral_nnnorm_add hfm hgm
... < ⊤ : add_lt_top.2 ⟨hfi, hgi⟩
lemma integrable_finset_sum {ι} [measurable_space β] [borel_space β]
[second_countable_topology β] (s : finset ι) {f : ι → α → β}
(hfm : ∀ i, measurable (f i)) (hfi : ∀ i, integrable (f i)) :
integrable (λ a, ∑ i in s, f i a) :=
begin
refine finset.induction_on s _ _,
{ simp only [finset.sum_empty, integrable_zero] },
{ assume i s his ih,
simp only [his, finset.sum_insert, not_false_iff],
refine (hfi _).add (hfm _) (s.measurable_sum hfm) ih }
end
lemma lintegral_nnnorm_neg {f : α → β} :
(∫⁻ (a : α), ↑(nnnorm ((-f) a))) = ∫⁻ (a : α), ↑(nnnorm ((f) a)) :=
by simp only [pi.neg_apply, nnnorm_neg]
lemma integrable.neg {f : α → β} : integrable f → integrable (λa, -f a) :=
assume hfi, calc _ = _ : lintegral_nnnorm_neg
... < ⊤ : hfi
@[simp] lemma integrable_neg_iff (f : α → β) : integrable (λa, -f a) ↔ integrable f :=
begin
split,
{ assume h,
simpa only [_root_.neg_neg] using h.neg },
exact integrable.neg
end
lemma integrable.sub [measurable_space β] [opens_measurable_space β]
{f g : α → β} (hfm : measurable f) (hfi : integrable f) (hgm : measurable g)
(hgi : integrable g) : integrable (λa, f a - g a) :=
calc
(∫⁻ (a : α), ↑(nnnorm ((f - g) a))) ≤ ∫⁻ (a : α), ↑(nnnorm (f a)) + ↑(nnnorm (-g a)) :
lintegral_mono
(assume a, by { simp only [← coe_add, coe_le_coe], exact nnnorm_add_le _ _ })
... = _ :
by { simp only [nnnorm_neg], exact lintegral_nnnorm_add hfm hgm }
... < ⊤ : add_lt_top.2 ⟨hfi, hgi⟩
lemma integrable.norm {f : α → β} (hfi : integrable f) : integrable (λa, ∥f a∥) :=
have eq : (λa, (nnnorm ∥f a∥ : ennreal)) = λa, (nnnorm (f a) : ennreal),
by { funext, rw nnnorm_norm },
by { rwa [integrable, eq] }
lemma integrable_norm_iff (f : α → β) : integrable (λa, ∥f a∥) ↔ integrable f :=
have eq : (λa, (nnnorm ∥f a∥ : ennreal)) = λa, (nnnorm (f a) : ennreal),
by { funext, rw nnnorm_norm },
by { rw [integrable, integrable, eq] }
lemma integrable_of_integrable_bound {f : α → β} {bound : α → ℝ} (h : integrable bound)
(h_bound : ∀ₘ a, ∥f a∥ ≤ bound a) : integrable f :=
have h₁ : ∀ₘ a, (nnnorm (f a) : ennreal) ≤ ennreal.of_real (bound a),
begin
filter_upwards [h_bound],
simp only [mem_set_of_eq],
assume a h,
calc (nnnorm (f a) : ennreal) = ennreal.of_real (∥f a∥) : by rw of_real_norm_eq_coe_nnnorm
... ≤ ennreal.of_real (bound a) : ennreal.of_real_le_of_real h
end,
calc (∫⁻ a, nnnorm (f a)) ≤ (∫⁻ a, ennreal.of_real (bound a)) :
by { apply lintegral_le_lintegral_ae, exact h₁ }
... ≤ (∫⁻ a, ennreal.of_real ∥bound a∥) : lintegral_mono $
by { assume a, apply ennreal.of_real_le_of_real, exact le_max_left (bound a) (-bound a) }
... < ⊤ : by { rwa [integrable_iff_norm] at h }
section dominated_convergence
variables {F : ℕ → α → β} {f : α → β} {bound : α → ℝ}
lemma all_ae_of_real_F_le_bound (h : ∀ n, ∀ₘ a, ∥F n a∥ ≤ bound a) :
∀ n, ∀ₘ a, ennreal.of_real ∥F n a∥ ≤ ennreal.of_real (bound a) :=
λn, by filter_upwards [h n] λ a h, ennreal.of_real_le_of_real h
lemma all_ae_tendsto_of_real_norm (h : ∀ₘ a, tendsto (λ n, F n a) at_top $ 𝓝 $ f a) :
∀ₘ a, tendsto (λn, ennreal.of_real ∥F n a∥) at_top $ 𝓝 $ ennreal.of_real ∥f a∥ :=
by filter_upwards [h]
λ a h, tendsto_of_real $ tendsto.comp (continuous.tendsto continuous_norm _) h
lemma all_ae_of_real_f_le_bound (h_bound : ∀ n, ∀ₘ a, ∥F n a∥ ≤ bound a)
(h_lim : ∀ₘ a, tendsto (λ n, F n a) at_top (𝓝 (f a))) :
∀ₘ a, ennreal.of_real ∥f a∥ ≤ ennreal.of_real (bound a) :=
begin
have F_le_bound := all_ae_of_real_F_le_bound h_bound,
rw ← ae_all_iff at F_le_bound,
apply F_le_bound.mp ((all_ae_tendsto_of_real_norm h_lim).mono _),
assume a tendsto_norm F_le_bound,
exact le_of_tendsto' at_top_ne_bot tendsto_norm (F_le_bound)
end
lemma integrable_of_dominated_convergence {F : ℕ → α → β} {f : α → β} {bound : α → ℝ}
(bound_integrable : integrable bound)
(h_bound : ∀ n, ∀ₘ a, ∥F n a∥ ≤ bound a)
(h_lim : ∀ₘ a, tendsto (λ n, F n a) at_top (𝓝 (f a))) :
integrable f :=
/- `∥F n a∥ ≤ bound a` and `∥F n a∥ --> ∥f a∥` implies `∥f a∥ ≤ bound a`,
and so `∫ ∥f∥ ≤ ∫ bound < ⊤` since `bound` is integrable -/
begin
rw integrable_iff_norm,
calc (∫⁻ a, (ennreal.of_real ∥f a∥)) ≤ ∫⁻ a, ennreal.of_real (bound a) :
lintegral_le_lintegral_ae $ all_ae_of_real_f_le_bound h_bound h_lim
... < ⊤ :
begin
rw ← integrable_iff_of_real,
{ exact bound_integrable },
filter_upwards [h_bound 0] λ a h, le_trans (norm_nonneg _) h,
end
end
lemma tendsto_lintegral_norm_of_dominated_convergence [measurable_space β]
[borel_space β] [second_countable_topology β]
{F : ℕ → α → β} {f : α → β} {bound : α → ℝ}
(F_measurable : ∀ n, measurable (F n))
(f_measurable : measurable f)
(bound_integrable : integrable bound)
(h_bound : ∀ n, ∀ₘ a, ∥F n a∥ ≤ bound a)
(h_lim : ∀ₘ a, tendsto (λ n, F n a) at_top (𝓝 (f a))) :
tendsto (λn, ∫⁻ a, ennreal.of_real ∥F n a - f a∥) at_top (𝓝 0) :=
let b := λa, 2 * ennreal.of_real (bound a) in
/- `∥F n a∥ ≤ bound a` and `F n a --> f a` implies `∥f a∥ ≤ bound a`, and thus by the
triangle inequality, have `∥F n a - f a∥ ≤ 2 * (bound a). -/
have hb : ∀ n, ∀ₘ a, ennreal.of_real ∥F n a - f a∥ ≤ b a,
begin
assume n,
filter_upwards [all_ae_of_real_F_le_bound h_bound n, all_ae_of_real_f_le_bound h_bound h_lim],
assume a h₁ h₂,
calc ennreal.of_real ∥F n a - f a∥ ≤ (ennreal.of_real ∥F n a∥) + (ennreal.of_real ∥f a∥) :
begin
rw [← ennreal.of_real_add],
apply of_real_le_of_real,
{ apply norm_sub_le }, { exact norm_nonneg _ }, { exact norm_nonneg _ }
end
... ≤ (ennreal.of_real (bound a)) + (ennreal.of_real (bound a)) : add_le_add h₁ h₂
... = b a : by rw ← two_mul
end,
/- On the other hand, `F n a --> f a` implies that `∥F n a - f a∥ --> 0` -/
have h : ∀ₘ a, tendsto (λ n, ennreal.of_real ∥F n a - f a∥) at_top (𝓝 0),
begin
suffices h : ∀ₘ a, tendsto (λ n, ennreal.of_real ∥F n a - f a∥) at_top (𝓝 $ ennreal.of_real 0),
{ rwa ennreal.of_real_zero at h },
filter_upwards [h_lim],
assume a h,
refine tendsto.comp (continuous.tendsto continuous_of_real _) _,
rw ← tendsto_iff_norm_tendsto_zero,
exact h
end,
/- Therefore, by the dominated convergence theorem for nonnegative integration, have
` ∫ ∥f a - F n a∥ --> 0 ` -/
begin
suffices h : tendsto (λn, ∫⁻ a, ennreal.of_real ∥F n a - f a∥) at_top (𝓝 (∫⁻ (a:α), 0)),
{ rwa lintegral_zero at h },
-- Using the dominated convergence theorem.
refine tendsto_lintegral_of_dominated_convergence _ _ hb _ _,
-- Show `λa, ∥f a - F n a∥` is measurable for all `n`
{ exact λn, measurable_of_real.comp ((F_measurable n).sub f_measurable).norm },
-- Show `2 * bound` is integrable
{ rw integrable_iff_of_real at bound_integrable,
{ calc (∫⁻ a, b a) = 2 * (∫⁻ a, ennreal.of_real (bound a)) :
by { rw lintegral_const_mul', exact coe_ne_top }
... < ⊤ : mul_lt_top (coe_lt_top) bound_integrable },
filter_upwards [h_bound 0] λ a h, le_trans (norm_nonneg _) h },
-- Show `∥f a - F n a∥ --> 0`
{ exact h }
end
end dominated_convergence
section pos_part
/-! Lemmas used for defining the positive part of a `L¹` function -/
lemma integrable.max_zero {f : α → ℝ} (hf : integrable f) : integrable (λa, max (f a) 0) :=
begin
simp only [integrable_iff_norm] at *,
calc (∫⁻ a, ennreal.of_real ∥max (f a) 0∥) ≤ (∫⁻ (a : α), ennreal.of_real ∥f a∥) :
lintegral_mono
begin
assume a,
apply of_real_le_of_real,
simp only [real.norm_eq_abs],
calc abs (max (f a) 0) = max (f a) 0 : by { rw abs_of_nonneg, apply le_max_right }
... ≤ abs (f a) : max_le (le_abs_self _) (abs_nonneg _)
end
... < ⊤ : hf
end
lemma integrable.min_zero {f : α → ℝ} (hf : integrable f) : integrable (λa, min (f a) 0) :=
begin
have : (λa, min (f a) 0) = (λa, - max (-f a) 0),
{ funext, rw [min_eq_neg_max_neg_neg, neg_zero] },
rw this,
exact (integrable.max_zero hf.neg).neg,
end
end pos_part
section normed_space
variables {𝕜 : Type*} [normed_field 𝕜] [normed_space 𝕜 β]
lemma integrable.smul (c : 𝕜) {f : α → β} : integrable f → integrable (λa, c • f a) :=
begin
simp only [integrable], assume hfi,
calc
(∫⁻ (a : α), nnnorm ((c • f) a)) = (∫⁻ (a : α), (nnnorm c) * nnnorm (f a)) :
begin
apply lintegral_congr_ae,
filter_upwards [],
assume a,
simp only [nnnorm_smul, set.mem_set_of_eq, pi.smul_apply, ennreal.coe_mul]
end
... < ⊤ :
begin
rw lintegral_const_mul',
apply mul_lt_top,
{ exact coe_lt_top },
{ exact hfi },
{ simp only [ennreal.coe_ne_top, ne.def, not_false_iff] }
end
end
lemma integrable_smul_iff {c : 𝕜} (hc : c ≠ 0) (f : α → β) :
integrable (λa, c • f a) ↔ integrable f :=
begin
split,
{ assume h,
simpa only [smul_smul, inv_mul_cancel hc, one_smul] using h.smul c⁻¹ },
exact integrable.smul _
end
end normed_space
variables [second_countable_topology β]
namespace ae_eq_fun
variable [measurable_space β]
section
variable [opens_measurable_space β]
/-- An almost everywhere equal function is `integrable` if it has a finite distance to the origin.
Should mean the same thing as the predicate `integrable` over functions. -/
def integrable (f : α →ₘ β) : Prop := f ∈ ball (0 : α →ₘ β) ⊤
lemma integrable_mk {f : α → β} (hf : measurable f) :
(integrable (mk f hf)) ↔ measure_theory.integrable f :=
by simp [integrable, zero_def, edist_mk_mk', measure_theory.integrable, nndist_eq_nnnorm]
lemma integrable_to_fun (f : α →ₘ β) : integrable f ↔ (measure_theory.integrable f.to_fun) :=
by conv_lhs { rw [self_eq_mk f, integrable_mk] }
local attribute [simp] integrable_mk
lemma integrable_zero : integrable (0 : α →ₘ β) := mem_ball_self coe_lt_top
end
section
variable [borel_space β]
lemma integrable.add :
∀ {f g : α →ₘ β}, integrable f → integrable g → integrable (f + g) :=
begin
rintros ⟨f, hf⟩ ⟨g, hg⟩,
simp only [mem_ball, zero_def, mk_add_mk, integrable_mk, quot_mk_eq_mk],
assume hfi hgi,
exact hfi.add hf hg hgi
end
lemma integrable.neg : ∀ {f : α →ₘ β}, integrable f → integrable (-f) :=
begin
rintros ⟨f, hfm⟩ hfi,
exact (integrable_mk _).2 ((integrable_mk hfm).1 hfi).neg
end
lemma integrable.sub :
∀ {f g : α →ₘ β}, integrable f → integrable g → integrable (f - g) :=
begin
rintros ⟨f, hfm⟩ ⟨g, hgm⟩,
simp only [quot_mk_eq_mk, integrable_mk, mk_sub_mk],
exact λ hfi hgi, hfi.sub hfm hgm hgi
end
protected lemma is_add_subgroup : is_add_subgroup (ball (0 : α →ₘ β) ⊤) :=
{ zero_mem := integrable_zero,
add_mem := λ _ _, integrable.add,
neg_mem := λ _, integrable.neg }
section normed_space
variables {𝕜 : Type*} [normed_field 𝕜] [normed_space 𝕜 β]
lemma integrable.smul : ∀ {c : 𝕜} {f : α →ₘ β}, integrable f → integrable (c • f) :=
begin
rintros c ⟨f, hfm⟩,
simp only [quot_mk_eq_mk, integrable_mk, smul_mk],
exact λ hfi, hfi.smul c
end
end normed_space
end
end ae_eq_fun
section
variables (α β) [measurable_space β] [opens_measurable_space β]
/-- The space of equivalence classes of integrable (and measurable) functions, where two integrable
functions are equivalent if they agree almost everywhere, i.e., they differ on a set of measure
`0`. -/
def l1 : Type (max u v) := subtype (@ae_eq_fun.integrable α _ β _ _ _ _)
infixr ` →₁ `:25 := l1
end
namespace l1
open ae_eq_fun
local attribute [instance] ae_eq_fun.is_add_subgroup
variables [measurable_space β]
section
variable [opens_measurable_space β]
instance : has_coe (α →₁ β) (α →ₘ β) := ⟨subtype.val⟩
protected lemma eq {f g : α →₁ β} : (f : α →ₘ β) = (g : α →ₘ β) → f = g := subtype.eq
@[norm_cast] protected lemma eq_iff {f g : α →₁ β} : (f : α →ₘ β) = (g : α →ₘ β) ↔ f = g :=
iff.intro (l1.eq) (congr_arg coe)
/- TODO : order structure of l1-/
/-- `L¹` space forms a `emetric_space`, with the emetric being inherited from almost everywhere
functions, i.e., `edist f g = ∫⁻ a, edist (f a) (g a)`. -/
instance : emetric_space (α →₁ β) := subtype.emetric_space
/-- `L¹` space forms a `metric_space`, with the metric being inherited from almost everywhere
functions, i.e., `edist f g = ennreal.to_real (∫⁻ a, edist (f a) (g a))`. -/
instance : metric_space (α →₁ β) := metric_space_emetric_ball 0 ⊤
end
variable [borel_space β]
instance : add_comm_group (α →₁ β) := subtype.add_comm_group
instance : inhabited (α →₁ β) := ⟨0⟩
@[simp, norm_cast] lemma coe_zero : ((0 : α →₁ β) : α →ₘ β) = 0 := rfl
@[simp, norm_cast] lemma coe_add (f g : α →₁ β) : ((f + g : α →₁ β) : α →ₘ β) = f + g := rfl
@[simp, norm_cast] lemma coe_neg (f : α →₁ β) : ((-f : α →₁ β) : α →ₘ β) = -f := rfl
@[simp, norm_cast] lemma coe_sub (f g : α →₁ β) : ((f - g : α →₁ β) : α →ₘ β) = f - g := rfl
@[simp] lemma edist_eq (f g : α →₁ β) : edist f g = edist (f : α →ₘ β) (g : α →ₘ β) := rfl
lemma dist_eq (f g : α →₁ β) : dist f g = ennreal.to_real (edist (f : α →ₘ β) (g : α →ₘ β)) := rfl
/-- The norm on `L¹` space is defined to be `∥f∥ = ∫⁻ a, edist (f a) 0`. -/
instance : has_norm (α →₁ β) := ⟨λ f, dist f 0⟩
lemma norm_eq (f : α →₁ β) : ∥f∥ = ennreal.to_real (edist (f : α →ₘ β) 0) := rfl
instance : normed_group (α →₁ β) := normed_group.of_add_dist (λ x, rfl) $ by
{ intros, simp only [dist_eq, coe_add], rw edist_eq_add_add }
section normed_space
variables {𝕜 : Type*} [normed_field 𝕜] [normed_space 𝕜 β]
instance : has_scalar 𝕜 (α →₁ β) := ⟨λ x f, ⟨x • (f : α →ₘ β), ae_eq_fun.integrable.smul f.2⟩⟩
@[simp, norm_cast] lemma coe_smul (c : 𝕜) (f : α →₁ β) :
((c • f : α →₁ β) : α →ₘ β) = c • (f : α →ₘ β) := rfl
instance : semimodule 𝕜 (α →₁ β) :=
{ one_smul := λf, l1.eq (by { simp only [coe_smul], exact one_smul _ _ }),
mul_smul := λx y f, l1.eq (by { simp only [coe_smul], exact mul_smul _ _ _ }),
smul_add := λx f g, l1.eq (by { simp only [coe_smul, coe_add], exact smul_add _ _ _ }),
smul_zero := λx, l1.eq (by { simp only [coe_zero, coe_smul], exact smul_zero _ }),
add_smul := λx y f, l1.eq (by { simp only [coe_smul], exact add_smul _ _ _ }),
zero_smul := λf, l1.eq (by { simp only [coe_smul], exact zero_smul _ _ }) }
instance : normed_space 𝕜 (α →₁ β) :=
⟨ begin
rintros x ⟨f, hf⟩,
show ennreal.to_real (edist (x • f) 0) ≤ ∥x∥ * ennreal.to_real (edist f 0),
rw [edist_smul, to_real_of_real_mul],
exact norm_nonneg _
end ⟩
end normed_space
section of_fun
/-- Construct the equivalence class `[f]` of a measurable and integrable function `f`. -/
def of_fun (f : α → β) (hfm : measurable f) (hfi : integrable f) : (α →₁ β) :=
⟨mk f hfm, by { rw integrable_mk, exact hfi }⟩
lemma of_fun_eq_mk (f : α → β) (hfm hfi) : (of_fun f hfm hfi : α →ₘ β) = mk f hfm := rfl
lemma of_fun_eq_of_fun (f g : α → β) (hfm hfi hgm hgi) :
of_fun f hfm hfi = of_fun g hgm hgi ↔ ∀ₘ a, f a = g a :=
by { rw ← l1.eq_iff, simp only [of_fun_eq_mk, mk_eq_mk] }
lemma of_fun_zero :
of_fun (λa:α, (0:β)) (@measurable_const _ _ _ _ (0:β)) (integrable_zero α β) = 0 := rfl
lemma of_fun_add (f g : α → β) (hfm hfi hgm hgi) :
of_fun (λa, f a + g a) (measurable.add hfm hgm) (integrable.add hfm hfi hgm hgi)
= of_fun f hfm hfi + of_fun g hgm hgi :=
rfl
lemma of_fun_neg (f : α → β) (hfm hfi) :
of_fun (λa, - f a) (measurable.neg hfm) (integrable.neg hfi) = - of_fun f hfm hfi := rfl
lemma of_fun_sub (f g : α → β) (hfm hfi hgm hgi) :
of_fun (λa, f a - g a) (measurable.sub hfm hgm) (integrable.sub hfm hfi hgm hgi)
= of_fun f hfm hfi - of_fun g hgm hgi :=
rfl
lemma norm_of_fun (f : α → β) (hfm hfi) :
∥of_fun f hfm hfi∥ = ennreal.to_real (∫⁻ a, edist (f a) 0) :=
rfl
lemma norm_of_fun_eq_lintegral_norm (f : α → β) (hfm hfi) :
∥of_fun f hfm hfi∥ = ennreal.to_real (∫⁻ a, ennreal.of_real ∥f a∥) :=
by { rw [norm_of_fun, lintegral_norm_eq_lintegral_edist] }
variables {𝕜 : Type*} [normed_field 𝕜] [normed_space 𝕜 β]
lemma of_fun_smul (f : α → β) (hfm : measurable f) (hfi : integrable f) (k : 𝕜) :
of_fun (λa, k • f a) (hfm.const_smul _) (hfi.smul _) = k • of_fun f hfm hfi := rfl
end of_fun
section to_fun
/-- Find a representative of an `L¹` function [f] -/
@[reducible]
protected def to_fun (f : α →₁ β) : α → β := (f : α →ₘ β).to_fun
protected lemma measurable (f : α →₁ β) : measurable f.to_fun := f.1.measurable
protected lemma integrable (f : α →₁ β) : integrable f.to_fun :=
by { rw [l1.to_fun, ← integrable_to_fun], exact f.2 }
lemma of_fun_to_fun (f : α →₁ β) : of_fun (f.to_fun) f.measurable f.integrable = f :=
begin
rcases f with ⟨f, hfi⟩,
rw [of_fun, subtype.mk_eq_mk],
exact (self_eq_mk f).symm
end
lemma mk_to_fun (f : α →₁ β) : mk (f.to_fun) f.measurable = f :=
by { rw ← of_fun_eq_mk, rw l1.eq_iff, exact of_fun_to_fun f }
lemma to_fun_of_fun (f : α → β) (hfm hfi) : ∀ₘ a, (of_fun f hfm hfi).to_fun a = f a :=
(all_ae_mk_to_fun f hfm).mono $ assume a, id
variables (α β)
lemma zero_to_fun : ∀ₘ a, (0 : α →₁ β).to_fun a = 0 := ae_eq_fun.zero_to_fun
variables {α β}
lemma add_to_fun (f g : α →₁ β) : ∀ₘ a, (f + g).to_fun a = f.to_fun a + g.to_fun a :=
ae_eq_fun.add_to_fun _ _
lemma neg_to_fun (f : α →₁ β) : ∀ₘ a, (-f).to_fun a = -f.to_fun a := ae_eq_fun.neg_to_fun _
lemma sub_to_fun (f g : α →₁ β) : ∀ₘ a, (f - g).to_fun a = f.to_fun a - g.to_fun a :=
ae_eq_fun.sub_to_fun _ _
lemma dist_to_fun (f g : α →₁ β) :
dist f g = ennreal.to_real (∫⁻ x, edist (f.to_fun x) (g.to_fun x)) :=
by { simp only [dist_eq, edist_to_fun] }
lemma norm_eq_nnnorm_to_fun (f : α →₁ β) : ∥f∥ = ennreal.to_real (∫⁻ a, nnnorm (f.to_fun a)) :=
by { rw [lintegral_nnnorm_eq_lintegral_edist, ← edist_zero_to_fun], refl }
lemma norm_eq_norm_to_fun (f : α →₁ β) :
∥f∥ = ennreal.to_real (∫⁻ a, ennreal.of_real ∥f.to_fun a∥) :=
by { rw norm_eq_nnnorm_to_fun, congr, funext, rw of_real_norm_eq_coe_nnnorm }
lemma lintegral_edist_to_fun_lt_top (f g : α →₁ β) : (∫⁻ a, edist (f.to_fun a) (g.to_fun a)) < ⊤ :=
begin
apply lintegral_edist_lt_top,
exact f.measurable, exact f.integrable, exact g.measurable, exact g.integrable
end
variables {𝕜 : Type*} [normed_field 𝕜] [normed_space 𝕜 β]
lemma smul_to_fun (c : 𝕜) (f : α →₁ β) : ∀ₘ a, (c • f).to_fun a = c • f.to_fun a :=
ae_eq_fun.smul_to_fun _ _
end to_fun
section pos_part
/-- Positive part of a function in `L¹` space. -/
def pos_part (f : α →₁ ℝ) : α →₁ ℝ :=
⟨ ae_eq_fun.pos_part f,
begin
rw [ae_eq_fun.integrable_to_fun, integrable_congr_ae (pos_part_to_fun _)],
exact integrable.max_zero f.integrable
end ⟩
/-- Negative part of a function in `L¹` space. -/
def neg_part (f : α →₁ ℝ) : α →₁ ℝ := pos_part (-f)
@[norm_cast] lemma coe_pos_part (f : α →₁ ℝ) : (f.pos_part : α →ₘ ℝ) = (f : α →ₘ ℝ).pos_part := rfl
lemma pos_part_to_fun (f : α →₁ ℝ) : ∀ₘ a, (pos_part f).to_fun a = max (f.to_fun a) 0 :=
ae_eq_fun.pos_part_to_fun _
lemma neg_part_to_fun_eq_max (f : α →₁ ℝ) : ∀ₘ a, (neg_part f).to_fun a = max (- f.to_fun a) 0 :=
begin
rw neg_part,
filter_upwards [pos_part_to_fun (-f), neg_to_fun f],
simp only [mem_set_of_eq],
assume a h₁ h₂,
rw [h₁, h₂]
end
lemma neg_part_to_fun_eq_min (f : α →₁ ℝ) : ∀ₘ a, (neg_part f).to_fun a = - min (f.to_fun a) 0 :=
begin
filter_upwards [neg_part_to_fun_eq_max f],
simp only [mem_set_of_eq],
assume a h,
rw [h, min_eq_neg_max_neg_neg, _root_.neg_neg, neg_zero],
end
lemma norm_le_norm_of_ae_le {f g : α →₁ β} (h : ∀ₘ a, ∥f.to_fun a∥ ≤ ∥g.to_fun a∥) : ∥f∥ ≤ ∥g∥ :=
begin
simp only [l1.norm_eq_norm_to_fun],
rw to_real_le_to_real,
{ apply lintegral_le_lintegral_ae,
filter_upwards [h],
simp only [mem_set_of_eq],
assume a h,
exact of_real_le_of_real h },
{ rw [← lt_top_iff_ne_top, ← integrable_iff_norm], exact f.integrable },
{ rw [← lt_top_iff_ne_top, ← integrable_iff_norm], exact g.integrable }
end
lemma continuous_pos_part : continuous $ λf : α →₁ ℝ, pos_part f :=
begin
simp only [metric.continuous_iff],
assume g ε hε,
use ε, use hε,
simp only [dist_eq_norm],
assume f hfg,
refine lt_of_le_of_lt (norm_le_norm_of_ae_le _) hfg,
filter_upwards [l1.sub_to_fun f g, l1.sub_to_fun (pos_part f) (pos_part g),
pos_part_to_fun f, pos_part_to_fun g],
simp only [mem_set_of_eq],
assume a h₁ h₂ h₃ h₄,
simp only [real.norm_eq_abs, h₁, h₂, h₃, h₄],
exact abs_max_sub_max_le_abs _ _ _
end
lemma continuous_neg_part : continuous $ λf : α →₁ ℝ, neg_part f :=
have eq : (λf : α →₁ ℝ, neg_part f) = (λf : α →₁ ℝ, pos_part (-f)) := rfl,
by { rw eq, exact continuous_pos_part.comp continuous_neg }
end pos_part
/- TODO: l1 is a complete space -/
end l1
end measure_theory
|
16e16f6b84b63f03b601e7b4f8242d236e1b7ade | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/analysis/analytic/uniqueness.lean | 65596baccb9b379398f77c2a4af56f3aa784f1e9 | [
"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 | 5,271 | lean | /-
Copyright (c) 2022 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Sébastien Gouëzel
-/
import analysis.analytic.linear
import analysis.analytic.composition
import analysis.normed_space.completion
/-!
# Uniqueness principle for analytic functions
We show that two analytic functions which coincide around a point coincide on whole connected sets,
in `analytic_on.eq_on_of_preconnected_of_eventually_eq`.
-/
variables {𝕜 : Type*} [nontrivially_normed_field 𝕜]
{E : Type*} [normed_add_comm_group E] [normed_space 𝕜 E]
{F : Type*} [normed_add_comm_group F] [normed_space 𝕜 F]
open set
open_locale topological_space ennreal
namespace analytic_on
/-- If an analytic function vanishes around a point, then it is uniformly zero along
a connected set. Superseded by `eq_on_zero_of_preconnected_of_locally_zero` which does not assume
completeness of the target space. -/
theorem eq_on_zero_of_preconnected_of_eventually_eq_zero_aux [complete_space F]
{f : E → F} {U : set E} (hf : analytic_on 𝕜 f U) (hU : is_preconnected U) {z₀ : E}
(h₀ : z₀ ∈ U) (hfz₀ : f =ᶠ[𝓝 z₀] 0) : eq_on f 0 U :=
begin
/- Let `u` be the set of points around which `f` vanishes. It is clearly open. We have to show
that its limit points in `U` still belong to it, from which the inclusion `U ⊆ u` will follow
by connectedness. -/
let u := {x | f =ᶠ[𝓝 x] 0},
suffices main : closure u ∩ U ⊆ u,
{ have Uu : U ⊆ u, from
hU.subset_of_closure_inter_subset is_open_set_of_eventually_nhds ⟨z₀, h₀, hfz₀⟩ main,
assume z hz,
simpa using mem_of_mem_nhds (Uu hz) },
/- Take a limit point `x`, then a ball `B (x, r)` on which it has a power series expansion, and
then `y ∈ B (x, r/2) ∩ u`. Then `f` has a power series expansion on `B (y, r/2)` as it is
contained in `B (x, r)`. All the coefficients in this series expansion vanish, as `f` is zero on a
neighborhood of `y`. Therefore, `f` is zero on `B (y, r/2)`. As this ball contains `x`, it follows
that `f` vanishes on a neighborhood of `x`, proving the claim. -/
rintros x ⟨xu, xU⟩,
rcases hf x xU with ⟨p, r, hp⟩,
obtain ⟨y, yu, hxy⟩ : ∃ y ∈ u, edist x y < r / 2,
from emetric.mem_closure_iff.1 xu (r / 2) (ennreal.half_pos hp.r_pos.ne'),
let q := p.change_origin (y - x),
have has_series : has_fpower_series_on_ball f q y (r / 2),
{ have A : (‖y - x‖₊ : ℝ≥0∞) < r / 2, by rwa [edist_comm, edist_eq_coe_nnnorm_sub] at hxy,
have := hp.change_origin (A.trans_le ennreal.half_le_self),
simp only [add_sub_cancel'_right] at this,
apply this.mono (ennreal.half_pos hp.r_pos.ne'),
apply ennreal.le_sub_of_add_le_left ennreal.coe_ne_top,
apply (add_le_add (A.le) (le_refl (r / 2))).trans (le_of_eq _),
exact ennreal.add_halves _ },
have M : emetric.ball y (r / 2) ∈ 𝓝 x, from emetric.is_open_ball.mem_nhds hxy,
filter_upwards [M] with z hz,
have A : has_sum (λ (n : ℕ), q n (λ (i : fin n), z - y)) (f z) := has_series.has_sum_sub hz,
have B : has_sum (λ (n : ℕ), q n (λ (i : fin n), z - y)) (0),
{ have : has_fpower_series_at 0 q y, from has_series.has_fpower_series_at.congr yu,
convert has_sum_zero,
ext n,
exact this.apply_eq_zero n _ },
exact has_sum.unique A B
end
/-- The *identity principle* for analytic functions: If an analytic function vanishes in a whole
neighborhood of a point `z₀`, then it is uniformly zero along a connected set. For a one-dimensional
version assuming only that the function vanishes at some points arbitrarily close to `z₀`, see
`eq_on_zero_of_preconnected_of_frequently_eq_zero`. -/
theorem eq_on_zero_of_preconnected_of_eventually_eq_zero
{f : E → F} {U : set E} (hf : analytic_on 𝕜 f U) (hU : is_preconnected U) {z₀ : E}
(h₀ : z₀ ∈ U) (hfz₀ : f =ᶠ[𝓝 z₀] 0) :
eq_on f 0 U :=
begin
let F' := uniform_space.completion F,
set e : F →L[𝕜] F' := uniform_space.completion.to_complL,
have : analytic_on 𝕜 (e ∘ f) U := λ x hx, (e.analytic_at _).comp (hf x hx),
have A : eq_on (e ∘ f) 0 U,
{ apply eq_on_zero_of_preconnected_of_eventually_eq_zero_aux this hU h₀,
filter_upwards [hfz₀] with x hx,
simp only [hx, function.comp_app, pi.zero_apply, map_zero] },
assume z hz,
have : e (f z) = e 0, by simpa only using A hz,
exact uniform_space.completion.coe_injective F this,
end
/-- The *identity principle* for analytic functions: If two analytic function coincide in a whole
neighborhood of a point `z₀`, then they coincide globally along a connected set.
For a one-dimensional version assuming only that the functions coincide at some points
arbitrarily close to `z₀`, see `eq_on_of_preconnected_of_frequently_eq`. -/
theorem eq_on_of_preconnected_of_eventually_eq
{f g : E → F} {U : set E} (hf : analytic_on 𝕜 f U) (hg : analytic_on 𝕜 g U)
(hU : is_preconnected U) {z₀ : E} (h₀ : z₀ ∈ U) (hfg : f =ᶠ[𝓝 z₀] g) :
eq_on f g U :=
begin
have hfg' : (f - g) =ᶠ[𝓝 z₀] 0 := hfg.mono (λ z h, by simp [h]),
simpa [sub_eq_zero] using
λ z hz, (hf.sub hg).eq_on_zero_of_preconnected_of_eventually_eq_zero hU h₀ hfg' hz,
end
end analytic_on
|
fa8f2faf08bbfd73320772f523129272addb54c5 | f20db13587f4dd28a4b1fbd31953afd491691fa0 | /library/init/category/state.lean | 071f7890d3a257257242cf9521eb45bf48758224 | [
"Apache-2.0"
] | permissive | AHartNtkn/lean | 9a971edfc6857c63edcbf96bea6841b9a84cf916 | 0d83a74b26541421fc1aa33044c35b03759710ed | refs/heads/master | 1,620,592,591,236 | 1,516,749,881,000 | 1,516,749,881,000 | 118,697,288 | 1 | 0 | null | 1,516,759,470,000 | 1,516,759,470,000 | null | UTF-8 | Lean | false | false | 3,543 | lean | /-
Copyright (c) 2016 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
prelude
import init.meta.interactive
universes u v
def state (σ α : Type u) : Type u :=
σ → α × σ
section
variables {σ α β : Type u}
@[inline] def state_return (a : α) : state σ α :=
λ s, (a, s)
@[inline] def state_bind (a : state σ α) (b : α → state σ β) : state σ β :=
λ s, match (a s) with (a', s') := b a' s' end
instance (σ : Type u) : monad (state σ) :=
{pure := @state_return σ, bind := @state_bind σ,
id_map := begin
intros, funext,
simp [state_bind], cases x s,
apply rfl
end,
pure_bind := by intros; apply rfl,
bind_assoc := begin
intros, funext,
simp [state_bind], cases x s,
apply rfl
end}
end
namespace state
@[inline] def read {σ : Type u} : state σ σ :=
λ s, (s, s)
@[inline] def write {σ : Type} : σ → state σ unit :=
λ s' s, ((), s')
@[inline] def write' {σ : Type u} : σ → state σ punit :=
λ s' s, (punit.star, s')
end state
def state_t (σ : Type u) (m : Type u → Type v) [monad m] (α : Type u) : Type (max u v) :=
σ → m (α × σ)
section
variable {σ : Type u}
variable {m : Type u → Type v}
variable [monad m]
variables {α β : Type u}
def state_t_return (a : α) : state_t σ m α :=
λ s, show m (α × σ), from
return (a, s)
def state_t_bind (act₁ : state_t σ m α) (act₂ : α → state_t σ m β) : state_t σ m β :=
λ s, show m (β × σ), from
do (a, new_s) ← act₁ s,
act₂ a new_s
end
instance (σ : Type u) (m : Type u → Type v) [monad m] : monad (state_t σ m) :=
{pure := @state_t_return σ m _, bind := @state_t_bind σ m _,
id_map := begin
intros, funext,
simp [state_t_bind, state_t_return, function.comp, return],
have h : state_t_bind._match_1 (λ (x : α) (s : σ), @pure m _ _ (x, s)) = pure,
{ funext s, cases s, apply rfl },
{ simp [h, monad.bind_pure] },
end,
pure_bind := begin
intros, funext,
simp [state_t_bind, state_t_return, monad.pure_bind]
end,
bind_assoc := begin
intros, funext,
simp [state_t_bind, state_t_return, monad.bind_assoc],
apply congr_arg, funext r,
cases r, refl
end}
section
variable {σ : Type u}
variable {m : Type u → Type v}
variable [monad m]
variable [alternative m]
variable {α : Type u}
def state_t_orelse (act₁ act₂ : state_t σ m α) : state_t σ m α :=
λ s, act₁ s <|> act₂ s
def state_t_failure : state_t σ m α :=
λ s, failure
end
instance (σ : Type u) (m : Type u → Type v) [alternative m] [monad m] : alternative (state_t σ m) :=
{ failure := @state_t_failure σ m _ _,
orelse := @state_t_orelse σ m _ _,
..state_t.monad σ m }
namespace state_t
def read {σ : Type u} {m : Type u → Type v} [monad m] : state_t σ m σ :=
λ s, return (s, s)
def write {σ : Type} {m : Type → Type v} [monad m] : σ → state_t σ m unit :=
λ s' s, return ((), s')
def write' {σ : Type u} {m : Type u → Type v} [monad m] : σ → state_t σ m punit :=
λ s' s, return (punit.star, s')
def modify {σ : Type} {m : Type → Type v} [monad m] (f : σ → σ) : state_t σ m unit :=
do s ← read, write (f s)
def modify' {σ : Type u} {m : Type u → Type v} [monad m] (f : σ → σ) : state_t σ m punit :=
do s ← read, write' (f s)
def lift {α σ : Type u} {m : Type u → Type v} [monad m] (t : m α) : state_t σ m α :=
λ s, do a ← t, return (a, s)
end state_t
|
60f78684f9afc18ef1e5182449ef04e10c443cda | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/algebra/category/Module/algebra.lean | ba74d2d24bfb0956803eebaf668e135d0750bfb4 | [
"Apache-2.0"
] | permissive | leanprover-community/mathlib | 56a2cadd17ac88caf4ece0a775932fa26327ba0e | 442a83d738cb208d3600056c489be16900ba701d | refs/heads/master | 1,693,584,102,358 | 1,693,471,902,000 | 1,693,471,902,000 | 97,922,418 | 1,595 | 352 | Apache-2.0 | 1,694,693,445,000 | 1,500,624,130,000 | Lean | UTF-8 | Lean | false | false | 2,065 | 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 algebra.algebra.restrict_scalars
import category_theory.linear.basic
import algebra.category.Module.basic
/-!
# Additional typeclass for modules over an algebra
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
For an object in `M : Module A`, where `A` is a `k`-algebra,
we provide additional typeclasses on the underlying type `M`,
namely `module k M` and `is_scalar_tower k A M`.
These are not made into instances by default.
We provide the `linear k (Module A)` instance.
## Note
If you begin with a `[module k M] [module A M] [is_scalar_tower k A M]`,
and build a bundled module via `Module.of A M`,
these instances will not necessarily agree with the original ones.
It seems without making a parallel version `Module' k A`, for modules over a `k`-algebra `A`,
that carries these typeclasses, this seems hard to achieve.
(An alternative would be to always require these typeclasses, and remove the original `Module`,
requiring users to write `Module' ℤ A` when `A` is merely a ring.)
-/
universes v u w
open category_theory
namespace Module
variables {k : Type u} [field k]
variables {A : Type w} [ring A] [algebra k A]
/--
Type synonym for considering a module over a `k`-algebra as a `k`-module.
-/
def module_of_algebra_Module (M : Module.{v} A) : module k M :=
restrict_scalars.module k A M
localized "attribute [instance] Module.module_of_algebra_Module" in Module
lemma is_scalar_tower_of_algebra_Module (M : Module.{v} A) : is_scalar_tower k A M :=
restrict_scalars.is_scalar_tower k A M
localized "attribute [instance] Module.is_scalar_tower_of_algebra_Module" in Module
-- We verify that the morphism spaces become `k`-modules.
example (M N : Module.{v} A) : module k (M ⟶ N) := by apply_instance
instance linear_over_field : linear k (Module.{v} A) :=
{ hom_module := λ M N, by apply_instance, }
end Module
|
c88929febdddd3ffd4896b565ad0c7c2fed8cb00 | a9d0fb7b0e4f802bd3857b803e6c5c23d87fef91 | /tests/lean/run/sorry.lean | 395ad20fd9b163435b9c81c232e4490accaf66a7 | [
"Apache-2.0"
] | permissive | soonhokong/lean-osx | 4a954262c780e404c1369d6c06516161d07fcb40 | 3670278342d2f4faa49d95b46d86642d7875b47c | refs/heads/master | 1,611,410,334,552 | 1,474,425,686,000 | 1,474,425,686,000 | 12,043,103 | 5 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 80 | lean | noncomputable definition b : Prop :=
sorry
theorem tst : true = false :=
sorry
|
97d7dca548d4bec2458a57a3b10e83172dc45e63 | 94e33a31faa76775069b071adea97e86e218a8ee | /test/polyrith.lean | 0662171f2d3161d22bf6bee43de114d0a6ffeae3 | [
"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 | 21,162 | lean | /-
Copyright (c) 2022 Dhruv Bhatia. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author(s): Dhruv Bhatia
-/
import tactic.polyrith
import data.real.basic
/-!
Each call to `polyrith` makes a call to the SageCell web API at
<https://sagecell.sagemath.org/>. To avoid making many API calls from CI,
we only test this communication in a few tests.
A full test suite is provided below the `#exit` command.
-/
/-!
## Set up testing infrastructre
-/
section tactic
open polyrith tactic
/--
For testing purposes, this behaves like `tactic.polyrith`, but takes an extra argument
representing the expected output from a call to Sage.
Allows for testing without actually making API calls.
-/
meta def tactic.test_polyrith (only_on : bool) (hyps : list pexpr)
(sage_out : json) (expected_args : list string) (expected_out : string) :
tactic unit := do
(eq_names, m, R, args) ← create_args only_on hyps,
guard (args = expected_args) <|>
fail!"expected arguments to Sage: {expected_args}\nbut produced: {args}",
out ← to_string <$> process_output eq_names m R sage_out,
guard (out = expected_out) <|>
fail!"expected final output: {expected_out}\nbut produced: {out}"
meta def format_string_list (input : list string) : string :=
to_string $ input.map (λ s, "\"" ++ s ++ "\"")
setup_tactic_parser
meta def tactic.interactive.test_polyrith (restr : parse (tk "only")?)
(hyps : parse pexpr_list?)
(sage_out : string) (expected_args : list string) (expected_out : string) : tactic unit := do
some sage_out ← return $ json.parse sage_out,
tactic.test_polyrith restr.is_some (hyps.get_or_else []) sage_out expected_args expected_out
meta def tactic.interactive.test_sage_output (restr : parse (tk "only")?)
(hyps : parse pexpr_list?) (expected_out : string) : tactic unit := do
expected_json ← json.parse expected_out,
sleep 10, -- otherwise can lead to weird errors when actively editing code with polyrith calls
(eq_names, m, R, args) ← create_args restr.is_some (hyps.get_or_else []),
sage_out ← sage_output args,
guard (sage_out = expected_json) <|>
fail!"Expected output from Sage: {expected_out}\nbut produced: {sage_out}"
/--
A convenience function. Given a working test, prints the code for a call to `test_sage_output`.
-/
meta def tactic.interactive.create_sage_output_test (restr : parse (tk "only")?)
(hyps : parse pexpr_list?) : tactic unit := do
let hyps := (hyps.get_or_else []),
sleep 10, -- otherwise can lead to weird errors when actively editing code with polyrith calls
(eq_names, m, R, args) ← create_args restr.is_some hyps,
sage_out ← to_string <$> sage_output args,
let sage_out := sage_out.fold "" (λ s c, s ++ (if c = '"' then "\\\"" else to_string c)),
let onl := if restr.is_some then "only " else "",
let hyps := if hyps = [] then "" else to_string hyps,
trace!"test_sage_output {onl}{hyps} \"{sage_out}\""
/--
A convenience function. Given a working test, prints the code for a call to `test_polyrith`.
-/
meta def tactic.interactive.create_polyrith_test (restr : parse (tk "only")?)
(hyps : parse pexpr_list?) : tactic unit := do
let hyps := (hyps.get_or_else []),
sleep 10, -- otherwise can lead to weird errors when actively editing code with polyrith calls
(eq_names, m, R, args) ← create_args restr.is_some hyps,
sage_out ← sage_output args,
out ← to_string <$> process_output eq_names m R sage_out,
let out := out.fold "" (λ s c, s ++ (if c = '"' then "\\\"" else to_string c)),
let sage_out := (to_string sage_out).fold ""
(λ s c, s ++ (if c = '"' then "\\\"" else to_string c)),
let argstring := format_string_list args,
let onl := if restr.is_some then "only " else "",
let hyps := if hyps = [] then "" else to_string hyps,
trace!"test_polyrith {onl}{hyps} \"{sage_out}\" {argstring} \"{out}\""
end tactic
/-!
## SageCell communcation tests
-/
example (x y : ℚ) (h1 : x*y + 2*x = 1) (h2 : x = y) :
x*y = -2*y + 1 :=
begin
test_sage_output "{\"data\":[\"(poly.const 1/1)\",\"(poly.const -2/1)\"],\"success\":true}",
linear_combination h1 - 2 * h2
end
example (w x y z : ℝ) (h1 : x + 2.1*y + 2*z = 2) (h2 : x + 8*z + 5*w = -6.5)
(h3 : x + y + 5*z + 5*w = 3) :
x + 2.2*y + 2*z - 5*w = -8.5 :=
begin
test_sage_output "{\"data\":[\"(poly.const 2/1)\",\"(poly.const 1/1)\",\"(poly.const -2/1)\"],\"success\":true}",
linear_combination 2 * h1 + h2 - 2 * h3
end
/-! ### Standard Cases over ℤ, ℚ, and ℝ -/
example (x y : ℤ) (h1 : 3*x + 2*y = 10):
3*x + 2*y = 10 :=
by test_polyrith "{\"data\":[\"(poly.const 1/1)\"],\"success\":true}" ["ff", "int", "2", "[(((3 * var0) + (2 * var1)) - 10)]", "(((3 * var0) + (2 * var1)) - 10)"] "linear_combination h1"
example (x y : ℚ) (h1 : x*y + 2*x = 1) (h2 : x = y) :
x*y = -2*y + 1 :=
by test_polyrith "{\"data\":[\"(poly.const 1/1)\",\"(poly.const -2/1)\"],\"success\":true}" ["ff", "rat", "2", "[(((var0 * var1) + (2 * var0)) - 1), (var0 - var1)]", "((var0 * var1) - (((-1 * 2) * var1) + 1))"] "linear_combination h1 - 2 * h2"
example (x y : ℝ) (h1 : x + 2 = -3) (h2 : y = 10) :
-y + 2*x + 4 = -16 :=
by test_polyrith "{\"data\":[\"(poly.const 2/1)\",\"(poly.const -1/1)\"],\"success\":true}" ["ff", "real", "2", "[((var1 + 2) - (-1 * 3)), (var0 - 10)]", "((((-1 * var0) + (2 * var1)) + 4) - (-1 * 16))"] "linear_combination 2 * h1 - h2"
example (x y z : ℝ) (ha : x + 2*y - z = 4) (hb : 2*x + y + z = -2)
(hc : x + 2*y + z = 2) :
-3*x - 3*y - 4*z = 2 :=
by test_polyrith "{\"data\":[\"(poly.const 1/1)\",\"(poly.const -1/1)\",\"(poly.const -2/1)\"],\"success\":true}" ["ff", "real", "3", "[(((var0 + (2 * var1)) - var2) - 4), ((((2 * var0) + var1) + var2) - (-1 * 2)), (((var0 + (2 * var1)) + var2) - 2)]", "(((((-1 * 3) * var0) - (3 * var1)) - (4 * var2)) - 2)"] "linear_combination ha - hb - 2 * hc"
example (w x y z : ℝ) (h1 : x + 2.1*y + 2*z = 2) (h2 : x + 8*z + 5*w = -6.5)
(h3 : x + y + 5*z + 5*w = 3) :
x + 2.2*y + 2*z - 5*w = -8.5 :=
by test_polyrith "{\"data\":[\"(poly.const 2/1)\",\"(poly.const 1/1)\",\"(poly.const -2/1)\"],\"success\":true}" ["ff", "real", "4", "[(((var0 + (21/10 * var1)) + (2 * var2)) - 2), (((var0 + (8 * var2)) + (5 * var3)) - (-1 * 13/2)), ((((var0 + var1) + (5 * var2)) + (5 * var3)) - 3)]", "((((var0 + (11/5 * var1)) + (2 * var2)) - (5 * var3)) - (-1 * 17/2))"] "linear_combination 2 * h1 + h2 - 2 * h3"
example (a b c d : ℚ) (h1 : a = 4) (h2 : 3 = b) (h3 : c*3 = d) (h4 : -d = a) :
2*a - 3 + 9*c + 3*d = 8 - b + 3*d - 3*a :=
by test_polyrith "{\"data\":[\"(poly.const 2/1)\",\"(poly.const -1/1)\",\"(poly.const 3/1)\",\"(poly.const -3/1)\"],\"success\":true}" ["ff", "rat", "4", "[(var0 - 4), (3 - var3), ((var1 * 3) - var2), ((-1 * var2) - var0)]", "(((((2 * var0) - 3) + (9 * var1)) + (3 * var2)) - (((8 - var3) + (3 * var2)) - (3 * var0)))"] "linear_combination 2 * h1 - h2 + 3 * h3 - 3 * h4"
/-! ### Case with ambiguous identifiers-/
example («def evil» y : ℤ) (h1 : 3*«def evil» + 2*y = 10):
3*«def evil» + 2*y = 10 :=
by test_polyrith "{\"data\":[\"(poly.const 1/1)\"],\"success\":true}" ["ff", "int", "2", "[(((3 * var0) + (2 * var1)) - 10)]", "(((3 * var0) + (2 * var1)) - 10)"] "linear_combination h1"
example («¥» y : ℤ) (h1 : 3*«¥» + 2*y = 10):
«¥» * (3*«¥» + 2*y) = 10 * «¥» :=
by test_polyrith "{\"data\":[\"(poly.mul (poly.const 1/1) (poly.var 0))\"],\"success\":true}" ["ff", "int", "2", "[(((3 * var0) + (2 * var1)) - 10)]", "((var0 * ((3 * var0) + (2 * var1))) - (10 * var0))"] "linear_combination 1 * «¥» * h1"
/-! ### Cases with arbitrary coefficients -/
example (a b : ℤ) (h : a = b) :
a * a = a * b :=
by test_polyrith "{\"data\":[\"(poly.mul (poly.const 1/1) (poly.var 0))\"],\"success\":true}" ["ff", "int", "2", "[(var0 - var1)]", "((var0 * var0) - (var0 * var1))"] "linear_combination 1 * a * h"
example (a b c : ℤ) (h : a = b) :
a * c = b * c :=
by test_polyrith "{\"data\":[\"(poly.mul (poly.const 1/1) (poly.var 1))\"],\"success\":true}" ["ff", "int", "3", "[(var0 - var2)]", "((var0 * var1) - (var2 * var1))"] "linear_combination 1 * c * h"
example (a b c : ℤ) (h1 : a = b) (h2 : b = 1) :
c * a + b = c * b + 1 :=
by test_polyrith "{\"data\":[\"(poly.mul (poly.const 1/1) (poly.var 0))\",\"(poly.const 1/1)\"],\"success\":true}" ["ff", "int", "3", "[(var1 - var2), (var2 - 1)]", "(((var0 * var1) + var2) - ((var0 * var2) + 1))"] "linear_combination 1 * c * h1 + h2"
example (x y : ℚ) (h1 : x + y = 3) (h2 : 3*x = 7) :
x*x*y + y*x*y + 6*x = 3*x*y + 14 :=
by test_polyrith "{\"data\":[\"(poly.mul (poly.mul (poly.const 1/1) (poly.var 0)) (poly.var 1))\",\"(poly.const 2/1)\"],\"success\":true}" ["ff", "rat", "2", "[((var0 + var1) - 3), ((3 * var0) - 7)]", "(((((var0 * var0) * var1) + ((var1 * var0) * var1)) + (6 * var0)) - (((3 * var0) * var1) + 14))"] "linear_combination 1 * x * y * h1 + 2 * h2"
example (x y z w : ℚ) (hzw : z = w) : x*z + 2*y*z = x*w + 2*y*w :=
by test_polyrith "{\"data\":[\"(poly.add (poly.mul (poly.const 1/1) (poly.var 0)) (poly.mul (poly.const 2/1) (poly.var 2)))\"],\"success\":true}" ["ff", "rat", "4", "[(var1 - var3)]", "(((var0 * var1) + ((2 * var2) * var1)) - ((var0 * var3) + ((2 * var2) * var3)))"] "linear_combination (1 * x + 2 * y) * hzw"
/-! ### Cases with non-hypothesis inputs/input restrictions -/
example (a b : ℝ) (ha : 2*a = 4) (hab : 2*b = a - b) (hignore : 3 = a + b) :
b = 2 / 3 :=
by test_polyrith only [ha, hab] "{\"data\":[\"(poly.const 1/6)\",\"(poly.const 1/3)\"],\"success\":true}" ["ff", "real", "2", "[((2 * var1) - 4), ((2 * var0) - (var1 - var0))]", "(var0 - 2/3)"] "linear_combination ha / 6 + hab / 3"
constant term : ∀ a b : ℚ, a + b = 0
example (a b c d : ℚ) (h : a + b = 0) (h2: b + c = 0): a + b + c + d = 0 :=
by test_polyrith only [term c d, h] "{\"data\":[\"(poly.const 1/1)\",\"(poly.const 1/1)\"],\"success\":true}" ["ff", "rat", "4", "[((var2 + var3) - 0), ((var0 + var1) - 0)]", "((((var0 + var1) + var2) + var3) - 0)"] "linear_combination term c d + h"
constants (qc : ℚ) (hqc : qc = 2*qc)
example (a b : ℚ) (h : ∀ p q : ℚ, p = q) : 3*a + qc = 3*b + 2*qc :=
by test_polyrith [h a b, hqc] "{\"data\":[\"(poly.const 3/1)\",\"(poly.const 1/1)\"],\"success\":true}" ["ff", "rat", "3", "[(var0 - var2), (var1 - (2 * var1))]", "(((3 * var0) + var1) - ((3 * var2) + (2 * var1)))"] "linear_combination 3 * h a b + hqc"
constant bad (q : ℚ) : q = 0
example (a b : ℚ) : a + b^3 = 0 :=
by test_polyrith [bad a, bad (b^2)] "{\"data\":[\"(poly.const 1/1)\",\"(poly.mul (poly.const 1/1) (poly.var 1))\"],\"success\":true}" ["ff", "rat", "2", "[(var0 - 0), ((var1 ^ 2) - 0)]", "((var0 + (var1 ^ 3)) - 0)"] "linear_combination bad a + 1 * b * bad (b ^ 2)"
/-! ### Case over arbitrary field/ring -/
example {α} [h : comm_ring α] {a b c d e f : α} (h1 : a*d = b*c) (h2 : c*f = e*d) :
c * (a*f - b*e) = 0 :=
by test_polyrith "{\"data\":[\"(poly.mul (poly.const 1/1) (poly.var 4))\",\"(poly.mul (poly.const 1/1) (poly.var 1))\"],\"success\":true}" ["ff", "α", "6", "[((var1 * var5) - (var3 * var0)), ((var0 * var2) - (var4 * var5))]", "((var0 * ((var1 * var2) - (var3 * var4))) - 0)"] "linear_combination 1 * e * h1 + 1 * a * h2"
example {K : Type*} [field K] [invertible 2] [invertible 3]
{ω p q r s t x: K} (hp_nonzero : p ≠ 0) (hr : r ^ 2 = q ^ 2 + p ^ 3) (hs3 : s ^ 3 = q + r)
(ht : t * s = p) (x : K) (H : 1 + ω + ω ^ 2 = 0) :
x ^ 3 + 3 * p * x - 2 * q =
(x - (s - t)) * (x - (s * ω - t * ω ^ 2)) * (x - (s * ω ^ 2 - t * ω)) :=
begin
have hs_nonzero : s ≠ 0,
{ contrapose! hp_nonzero with hs_nonzero,
test_polyrith "{\"data\":[\"(poly.const 0/1)\",\"(poly.const 0/1)\",\"(poly.const -1/1)\",\"(poly.const 0/1)\",\"(poly.mul (poly.const 1/1) (poly.var 4))\"],\"success\":true}" ["ff", "K", "6", "[((var1 ^ 2) - ((var2 ^ 2) + (var0 ^ 3))), ((var3 ^ 3) - (var2 + var1)), ((var4 * var3) - var0), (((1 + var5) + (var5 ^ 2)) - 0), (var3 - 0)]", "(var0 - 0)"] "linear_combination -ht + 1 * t * hs_nonzero" },
have H' : 2 * q = s ^ 3 - t ^ 3,
{ rw ← mul_left_inj' (pow_ne_zero 3 hs_nonzero),
test_polyrith "{\"data\":[\"(poly.const -1/1)\",\"(poly.add (poly.add (poly.mul (poly.const -1/1) (poly.pow (poly.var 1) 3)) (poly.mul (poly.const 1/1) (poly.var 0))) (poly.mul (poly.const -1/1) (poly.var 3)))\",\"(poly.add (poly.add (poly.mul (poly.mul (poly.const 1/1) (poly.pow (poly.var 1) 2)) (poly.pow (poly.var 2) 2)) (poly.mul (poly.mul (poly.mul (poly.const 1/1) (poly.var 1)) (poly.var 2)) (poly.var 4))) (poly.mul (poly.const 1/1) (poly.pow (poly.var 4) 2)))\",\"(poly.const 0/1)\"],\"success\":true}" ["ff", "K", "6", "[((var3 ^ 2) - ((var0 ^ 2) + (var4 ^ 3))), ((var1 ^ 3) - (var0 + var3)), ((var2 * var1) - var4), (((1 + var5) + (var5 ^ 2)) - 0)]", "(((2 * var0) * (var1 ^ 3)) - (((var1 ^ 3) - (var2 ^ 3)) * (var1 ^ 3)))"] "linear_combination -hr + ((-1) * s ^ 3 + 1 * q + (-1) * r) * hs3 + (1 * s ^ 2 * t ^ 2 + 1 * s * t * p + 1 * p ^ 2) * ht" },
test_polyrith "{\"data\":[\"(poly.const 0/1)\",\"(poly.const 0/1)\",\"(poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.mul (poly.mul (poly.const 1/1) (poly.var 0)) (poly.pow (poly.var 5) 4)) (poly.mul (poly.mul (poly.const -1/1) (poly.var 3)) (poly.pow (poly.var 5) 4))) (poly.mul (poly.mul (poly.const 1/1) (poly.var 4)) (poly.pow (poly.var 5) 4))) (poly.mul (poly.mul (poly.const -1/1) (poly.var 3)) (poly.pow (poly.var 5) 3))) (poly.mul (poly.mul (poly.const 1/1) (poly.var 4)) (poly.pow (poly.var 5) 3))) (poly.mul (poly.mul (poly.const 3/1) (poly.var 0)) (poly.pow (poly.var 5) 2))) (poly.mul (poly.mul (poly.const -1/1) (poly.var 3)) (poly.pow (poly.var 5) 2))) (poly.mul (poly.mul (poly.const 1/1) (poly.var 4)) (poly.pow (poly.var 5) 2))) (poly.mul (poly.mul (poly.const 2/1) (poly.var 0)) (poly.var 5)))\",\"(poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.add (poly.mul (poly.mul (poly.mul (poly.const -1/1) (poly.var 0)) (poly.pow (poly.var 3) 2)) (poly.var 5)) (poly.mul (poly.mul (poly.const 1/1) (poly.pow (poly.var 3) 3)) (poly.var 5))) (poly.mul (poly.mul (poly.mul (poly.const -1/1) (poly.var 0)) (poly.pow (poly.var 4) 2)) (poly.var 5))) (poly.mul (poly.mul (poly.const -1/1) (poly.pow (poly.var 4) 3)) (poly.var 5))) (poly.mul (poly.mul (poly.mul (poly.const 1/1) (poly.var 0)) (poly.var 1)) (poly.pow (poly.var 5) 2))) (poly.mul (poly.mul (poly.mul (poly.const -1/1) (poly.var 1)) (poly.var 3)) (poly.pow (poly.var 5) 2))) (poly.mul (poly.mul (poly.mul (poly.const 1/1) (poly.var 1)) (poly.var 4)) (poly.pow (poly.var 5) 2))) (poly.mul (poly.mul (poly.const 1/1) (poly.pow (poly.var 0) 2)) (poly.var 3))) (poly.mul (poly.const -1/1) (poly.pow (poly.var 3) 3))) (poly.mul (poly.mul (poly.const -1/1) (poly.pow (poly.var 0) 2)) (poly.var 4))) (poly.mul (poly.const 1/1) (poly.pow (poly.var 4) 3))) (poly.mul (poly.mul (poly.mul (poly.const -1/1) (poly.var 0)) (poly.var 1)) (poly.var 5))) (poly.mul (poly.mul (poly.const 3/1) (poly.var 0)) (poly.var 1)))\",\"(poly.const -1/1)\"],\"success\":true}" ["ff", "K", "7", "[((var6 ^ 2) - ((var2 ^ 2) + (var1 ^ 3))), ((var3 ^ 3) - (var2 + var6)), ((var4 * var3) - var1), (((1 + var5) + (var5 ^ 2)) - 0), ((2 * var2) - ((var3 ^ 3) - (var4 ^ 3)))]", "((((var0 ^ 3) + ((3 * var1) * var0)) - (2 * var2)) - (((var0 - (var3 - var4)) * (var0 - ((var3 * var5) - (var4 * (var5 ^ 2))))) * (var0 - ((var3 * (var5 ^ 2)) - (var4 * var5)))))"] "linear_combination (1 * x * ω ^ 4 + (-1) * s * ω ^ 4 + 1 * t * ω ^ 4 + (-1) * s * ω ^ 3 + 1 * t * ω ^ 3 +
3 * x * ω ^ 2 +
(-1) * s * ω ^ 2 +
1 * t * ω ^ 2 +
2 * x * ω) * ht + ((-1) * x * s ^ 2 * ω + 1 * s ^ 3 * ω + (-1) * x * t ^ 2 * ω + (-1) * t ^ 3 * ω +
1 * x * p * ω ^ 2 +
(-1) * p * s * ω ^ 2 +
1 * p * t * ω ^ 2 +
1 * x ^ 2 * s +
(-1) * s ^ 3 +
(-1) * x ^ 2 * t +
1 * t ^ 3 +
(-1) * x * p * ω +
3 * x * p) * H - H'"
end
/-! ## Degenerate cases -/
example {K : Type*} [field K] [char_zero K] {s : K} (hs : 3 * s + 1 = 4) : s = 1 :=
by test_polyrith "{\"data\":[\"(poly.const 1/3)\"],\"success\":true}" ["ff", "K", "1", "[(((3 * var0) + 1) - 4)]", "(var0 - 1)"] "linear_combination hs / 3"
example {x : ℤ} (h1 : x + 4 = 2) : x = -2 :=
by test_polyrith "{\"data\":[\"(poly.const 1/1)\"],\"success\":true}" ["ff", "int", "1", "[((var0 + 4) - 2)]", "(var0 - (-1 * 2))"] "linear_combination h1"
example {w : ℚ} (h1 : 3 * w + 1 = 4) : w = 1 :=
by test_polyrith "{\"data\":[\"(poly.const 1/3)\"],\"success\":true}" ["ff", "rat", "1", "[(((3 * var0) + 1) - 4)]", "(var0 - 1)"] "linear_combination h1 / 3"
example {x : ℤ} (h1 : 2 * x + 3 = x) : x = -3 :=
by test_polyrith "{\"data\":[\"(poly.const 1/1)\"],\"success\":true}" ["ff", "int", "1", "[(((2 * var0) + 3) - var0)]", "(var0 - (-1 * 3))"] "linear_combination h1"
example {c : ℚ} (h1 : 4 * c + 1 = 3 * c - 2) : c = -3 :=
by test_polyrith "{\"data\":[\"(poly.const 1/1)\"],\"success\":true}" ["ff", "rat", "1", "[(((4 * var0) + 1) - ((3 * var0) - 2))]", "(var0 - (-1 * 3))"] "linear_combination h1"
example (z : ℤ) (h1 : z + 1 = 2) (h2 : z + 2 = 2) : (1 : ℤ) = 2 :=
by test_polyrith "{\"data\":[\"(poly.const 1/1)\",\"(poly.const -1/1)\"],\"success\":true}" ["ff", "int", "1", "[((var0 + 1) - 2), ((var0 + 2) - 2)]", "(1 - 2)"] "linear_combination h1 - h2"
-- We comment the following tests so that we don't overwhelm the SageCell API.
/-
/-! ### Standard Cases over ℤ, ℚ, and ℝ -/
example (x y : ℤ) (h1 : 3*x + 2*y = 10):
3*x + 2*y = 10 :=
by polyrith
example (x y : ℚ) (h1 : x*y + 2*x = 1) (h2 : x = y) :
x*y = -2*y + 1 :=
by polyrith
example (x y : ℝ) (h1 : x + 2 = -3) (h2 : y = 10) :
-y + 2*x + 4 = -16 :=
by polyrith
example (x y z : ℝ) (ha : x + 2*y - z = 4) (hb : 2*x + y + z = -2)
(hc : x + 2*y + z = 2) :
-3*x - 3*y - 4*z = 2 :=
by polyrith
example (w x y z : ℝ) (h1 : x + 2.1*y + 2*z = 2) (h2 : x + 8*z + 5*w = -6.5)
(h3 : x + y + 5*z + 5*w = 3) :
x + 2.2*y + 2*z - 5*w = -8.5 :=
by polyrith
example (a b c d : ℚ) (h1 : a = 4) (h2 : 3 = b) (h3 : c*3 = d) (h4 : -d = a) :
2*a - 3 + 9*c + 3*d = 8 - b + 3*d - 3*a :=
by polyrith
/-! ### Case with ambiguous identifiers-/
example («def evil» y : ℤ) (h1 : 3*«def evil» + 2*y = 10):
3*«def evil» + 2*y = 10 :=
by polyrith
example («¥» y : ℤ) (h1 : 3*«¥» + 2*y = 10):
«¥» * (3*«¥» + 2*y) = 10 * «¥» :=
by polyrith
/-! ### Cases with arbitrary coefficients -/
example (a b : ℤ) (h : a = b) :
a * a = a * b :=
by polyrith
example (a b c : ℤ) (h : a = b) :
a * c = b * c :=
by polyrith
example (a b c : ℤ) (h1 : a = b) (h2 : b = 1) :
c * a + b = c * b + 1 :=
by polyrith
example (x y : ℚ) (h1 : x + y = 3) (h2 : 3*x = 7) :
x*x*y + y*x*y + 6*x = 3*x*y + 14 :=
by polyrith
example (x y z w : ℚ) (hzw : z = w) : x*z + 2*y*z = x*w + 2*y*w :=
by polyrith
/-! ### Cases with non-hypothesis inputs/input restrictions -/
example (a b : ℝ) (ha : 2*a = 4) (hab : 2*b = a - b) (hignore : 3 = a + b) :
b = 2 / 3 :=
by polyrith only [ha, hab]
-- constant term : ∀ a b : ℚ, a + b = 0
example (a b c d : ℚ) (h : a + b = 0) (h2: b + c = 0): a + b + c + d = 0 :=
by polyrith only [term c d, h]
-- constants (qc : ℚ) (hqc : qc = 2*qc)
example (a b : ℚ) (h : ∀ p q : ℚ, p = q) : 3*a + qc = 3*b + 2*qc :=
by polyrith [h a b, hqc]
-- constant bad (q : ℚ) : q = 0
example (a b : ℚ) : a + b^3 = 0 :=
by polyrith [bad a, bad (b^2)]
/-! ### Case over arbitrary field/ring -/
example {α} [h : comm_ring α] {a b c d e f : α} (h1 : a*d = b*c) (h2 : c*f = e*d) :
c * (a*f - b*e) = 0 :=
by polyrith
example {K : Type*} [field K] [invertible 2] [invertible 3]
{ω p q r s t x: K} (hp_nonzero : p ≠ 0) (hr : r ^ 2 = q ^ 2 + p ^ 3) (hs3 : s ^ 3 = q + r)
(ht : t * s = p) (x : K) (H : 1 + ω + ω ^ 2 = 0) :
x ^ 3 + 3 * p * x - 2 * q =
(x - (s - t)) * (x - (s * ω - t * ω ^ 2)) * (x - (s * ω ^ 2 - t * ω)) :=
begin
have hs_nonzero : s ≠ 0,
{ contrapose! hp_nonzero with hs_nonzero,
polyrith,
},
have H' : 2 * q = s ^ 3 - t ^ 3,
{ rw ← mul_left_inj' (pow_ne_zero 3 hs_nonzero),
polyrith,},
polyrith,
end
/-!
### With trace enabled
Here, the tactic will trace the command that gets sent to sage,
and so the tactic will not prove the goal. `linear_combination`
is called manually to prevent errors.
-/
set_option trace.polyrith true
example (x y : ℝ) (h1 : x + 2 = -3) (h2 : y = 10) :
-y + 2*x + 4 = -16 :=
begin
polyrith,
linear_combination 2 * h1 - h2,
end
example (a b c : ℤ) (h1 : a = b) (h2 : b = 1) :
c * a + b = c * b + 1 :=
begin
polyrith,
linear_combination c * h1 + h2,
end
example (a b c d : ℚ) (h : a + b = 0) (h2: b + c = 0): a + b + c + d = 0 :=
begin
polyrith only [term c d, h],
linear_combination term c d + h,
end
example (a b : ℚ) (h : ∀ p q : ℚ, p = q) : 3*a + qc = 3*b + 2*qc :=
begin
polyrith [h a b, hqc],
linear_combination 3 * h a b + hqc,
end
-/
|
96273ae3228fad91815bf80e3a0715fc7e7d4bcd | a9d0fb7b0e4f802bd3857b803e6c5c23d87fef91 | /hott/algebra/category/limits/functor.hlean | aadd4e3a433d78e1a33d73ec71644d5ac1cdc14e | [
"Apache-2.0"
] | permissive | soonhokong/lean-osx | 4a954262c780e404c1369d6c06516161d07fcb40 | 3670278342d2f4faa49d95b46d86642d7875b47c | refs/heads/master | 1,611,410,334,552 | 1,474,425,686,000 | 1,474,425,686,000 | 12,043,103 | 5 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 6,645 | hlean | /-
Copyright (c) 2015 Floris van Doorn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Floris van Doorn, Jakob von Raumer
Functor category has (co)limits if the codomain has them
-/
import .colimits
open functor nat_trans eq is_trunc
namespace category
-- preservation of limits
variables {D C I : Precategory}
definition functor_limit_object [constructor]
[H : has_limits_of_shape D I] (F : I ⇒ D ^c C) : C ⇒ D :=
begin
have lem : Π(c d : carrier C) (f : hom c d) ⦃i j : carrier I⦄ (k : i ⟶ j),
(constant2_functor F d) k ∘ to_fun_hom (F i) f ∘ limit_morphism (constant2_functor F c) i =
to_fun_hom (F j) f ∘ limit_morphism (constant2_functor F c) j,
begin intro c d f i j k, rewrite [-limit_commute _ k,▸*,+assoc,▸*,-naturality (F k) f] end,
fapply functor.mk,
{ intro c, exact limit_object (constant2_functor F c)},
{ intro c d f, fapply hom_limit,
{ intro i, refine to_fun_hom (F i) f ∘ !limit_morphism},
{ apply lem}},
{ exact abstract begin intro c, symmetry, apply eq_hom_limit, intro i,
rewrite [id_right,respect_id,▸*,id_left] end end},
{ intro a b c g f, symmetry, apply eq_hom_limit, intro i, -- report: adding abstract fails here
rewrite [respect_comp,assoc,hom_limit_commute,-assoc,hom_limit_commute,assoc]}
end
definition functor_limit_cone [constructor]
[H : has_limits_of_shape D I] (F : I ⇒ D ^c C) : cone_obj F :=
begin
fapply cone_obj.mk,
{ exact functor_limit_object F},
{ fapply nat_trans.mk,
{ intro i, esimp, fapply nat_trans.mk,
{ intro c, esimp, apply limit_morphism},
{ intro c d f, rewrite [▸*,hom_limit_commute (constant2_functor F d)]}},
{ intro i j k, apply nat_trans_eq, intro c,
rewrite [▸*,id_right,limit_commute (constant2_functor F c)]}}
end
variables (D C I)
definition has_limits_of_shape_functor [instance] [H : has_limits_of_shape D I]
: has_limits_of_shape (D ^c C) I :=
begin
intro F, fapply has_terminal_object.mk,
{ exact functor_limit_cone F},
{ intro c, esimp at *, induction c with G η, induction η with η p, esimp at *,
fapply is_contr.mk,
{ fapply cone_hom.mk,
{ fapply nat_trans.mk,
{ intro c, esimp, fapply hom_limit,
{ intro i, esimp, exact η i c},
{ intro i j k, esimp, exact ap010 natural_map (p k) c ⬝ !id_right}},
{ intro c d f, esimp, fapply @limit_cone_unique,
{ intro i, esimp, exact to_fun_hom (F i) f ∘ η i c},
{ intro i j k, rewrite [▸*,assoc,-naturality,-assoc,-compose_def,p k,▸*,id_right]},
{ intro i, rewrite [assoc, hom_limit_commute (constant2_functor F d),▸*,-assoc,
hom_limit_commute]},
{ intro i, rewrite [assoc, hom_limit_commute (constant2_functor F d),naturality]}}},
{ intro i, apply nat_trans_eq, intro c,
rewrite [▸*,hom_limit_commute (constant2_functor F c)]}},
{ intro h, induction h with f q, apply cone_hom_eq,
apply nat_trans_eq, intro c, esimp at *, symmetry,
apply eq_hom_limit, intro i, exact ap010 natural_map (q i) c}}
end
definition is_complete_functor [instance] [H : is_complete D] : is_complete (D ^c C) :=
λI, _
variables {D C I}
-- preservation of colimits
-- definition constant2_functor_op [constructor] (F : I ⇒ (D ^c C)ᵒᵖ) (c : C) : I ⇒ D :=
-- proof
-- functor.mk (λi, to_fun_ob (F i) c)
-- (λi j f, natural_map (F f) c)
-- abstract (λi, ap010 natural_map !respect_id c ⬝ proof idp qed) end
-- abstract (λi j k g f, ap010 natural_map !respect_comp c) end
-- qed
definition functor_colimit_object [constructor]
[H : has_colimits_of_shape D I] (F : Iᵒᵖ ⇒ (D ^c C)ᵒᵖ) : C ⇒ D :=
begin
fapply functor.mk,
{ intro c, exact colimit_object (constant2_functor Fᵒᵖ' c)},
{ intro c d f, apply colimit_hom_colimit, apply constant2_functor_natural _ f},
{ exact abstract begin intro c, symmetry, apply eq_colimit_hom, intro i,
rewrite [id_left,▸*,respect_id,id_right] end end},
{ intro a b c g f, symmetry, apply eq_colimit_hom, intro i, -- report: adding abstract fails here
rewrite [▸*,respect_comp,-assoc,colimit_hom_commute,assoc,colimit_hom_commute,-assoc]}
end
definition functor_colimit_cone [constructor]
[H : has_colimits_of_shape D I] (F : Iᵒᵖ ⇒ (D ^c C)ᵒᵖ) : cone_obj F :=
begin
fapply cone_obj.mk,
{ exact functor_colimit_object F},
{ fapply nat_trans.mk,
{ intro i, esimp, fapply nat_trans.mk,
{ intro c, esimp, apply colimit_morphism},
{ intro c d f, apply colimit_hom_commute (constant2_functor Fᵒᵖ' c)}},
{ intro i j k, apply nat_trans_eq, intro c,
rewrite [▸*,id_left], apply colimit_commute (constant2_functor Fᵒᵖ' c)}}
end
variables (D C I)
definition has_colimits_of_shape_functor [instance] [H : has_colimits_of_shape D I]
: has_colimits_of_shape (D ^c C) I :=
begin
intro F, fapply has_terminal_object.mk,
{ exact functor_colimit_cone F},
{ intro c, esimp at *, induction c with G η, induction η with η p, esimp at *,
fapply is_contr.mk,
{ fapply cone_hom.mk,
{ fapply nat_trans.mk,
{ intro c, esimp, fapply colimit_hom,
{ intro i, esimp, exact η i c},
{ intro i j k, esimp, exact ap010 natural_map (p k) c ⬝ !id_left}},
{ intro c d f, esimp, fapply @colimit_cocone_unique,
{ intro i, esimp, exact η i d ∘ to_fun_hom (F i) f},
{ intro i j k, rewrite [▸*,-assoc,naturality,assoc,-compose_def,p k,▸*,id_left]},
{ intro i, rewrite [-assoc, colimit_hom_commute (constant2_functor Fᵒᵖ' c),
▸*, naturality]},
{ intro i, rewrite [-assoc, colimit_hom_commute (constant2_functor Fᵒᵖ' c),▸*,assoc,
colimit_hom_commute (constant2_functor Fᵒᵖ' d)]}}},
{ intro i, apply nat_trans_eq, intro c,
rewrite [▸*,colimit_hom_commute (constant2_functor Fᵒᵖ' c)]}},
{ intro h, induction h with f q, apply cone_hom_eq,
apply nat_trans_eq, intro c, esimp at *, symmetry,
apply eq_colimit_hom, intro i, exact ap010 natural_map (q i) c}}
end
local attribute has_limits_of_shape_op_op [instance] [priority 1]
universe variables u v
definition is_cocomplete_functor [instance] [H : is_cocomplete.{_ _ u v} D]
: is_cocomplete.{_ _ u v} (D ^c C) :=
λI, _
end category
|
6ddfe0884179c6497a8979d0c08d6fc33243af4b | c777c32c8e484e195053731103c5e52af26a25d1 | /src/algebra/group/opposite.lean | 18f3d07d6c75f34df5c34d8db97988de40fa3451 | [
"Apache-2.0"
] | permissive | kbuzzard/mathlib | 2ff9e85dfe2a46f4b291927f983afec17e946eb8 | 58537299e922f9c77df76cb613910914a479c1f7 | refs/heads/master | 1,685,313,702,744 | 1,683,974,212,000 | 1,683,974,212,000 | 128,185,277 | 1 | 0 | null | 1,522,920,600,000 | 1,522,920,600,000 | null | UTF-8 | Lean | false | false | 23,079 | lean | /-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau
-/
import algebra.group.inj_surj
import algebra.group.commute
import algebra.hom.equiv.basic
import algebra.opposites
import data.int.cast.defs
/-!
# Group structures on the multiplicative and additive opposites
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
-/
universes u v
variables (α : Type u)
namespace mul_opposite
/-!
### Additive structures on `αᵐᵒᵖ`
-/
@[to_additive] instance [has_nat_cast α] : has_nat_cast αᵐᵒᵖ := ⟨λ n, op n⟩
@[to_additive] instance [has_int_cast α] : has_int_cast αᵐᵒᵖ := ⟨λ n, op n⟩
instance [add_semigroup α] : add_semigroup (αᵐᵒᵖ) :=
unop_injective.add_semigroup _ (λ x y, rfl)
instance [add_left_cancel_semigroup α] : add_left_cancel_semigroup αᵐᵒᵖ :=
unop_injective.add_left_cancel_semigroup _ (λ x y, rfl)
instance [add_right_cancel_semigroup α] : add_right_cancel_semigroup αᵐᵒᵖ :=
unop_injective.add_right_cancel_semigroup _ (λ x y, rfl)
instance [add_comm_semigroup α] : add_comm_semigroup αᵐᵒᵖ :=
unop_injective.add_comm_semigroup _ (λ x y, rfl)
instance [add_zero_class α] : add_zero_class αᵐᵒᵖ :=
unop_injective.add_zero_class _ rfl (λ x y, rfl)
instance [add_monoid α] : add_monoid αᵐᵒᵖ :=
unop_injective.add_monoid _ rfl (λ _ _, rfl) (λ _ _, rfl)
instance [add_comm_monoid α] : add_comm_monoid αᵐᵒᵖ :=
unop_injective.add_comm_monoid _ rfl (λ _ _, rfl) (λ _ _, rfl)
instance [add_monoid_with_one α] : add_monoid_with_one αᵐᵒᵖ :=
{ nat_cast_zero := show op ((0 : ℕ) : α) = 0, by rw [nat.cast_zero, op_zero],
nat_cast_succ := show ∀ n, op ((n + 1 : ℕ) : α) = op (n : ℕ) + 1, by simp,
.. mul_opposite.add_monoid α, .. mul_opposite.has_one α, ..mul_opposite.has_nat_cast _ }
instance [add_comm_monoid_with_one α] : add_comm_monoid_with_one αᵐᵒᵖ :=
{ .. mul_opposite.add_monoid_with_one α, ..mul_opposite.add_comm_monoid α }
instance [sub_neg_monoid α] : sub_neg_monoid αᵐᵒᵖ :=
unop_injective.sub_neg_monoid _ rfl (λ _ _, rfl) (λ _, rfl) (λ _ _, rfl) (λ _ _, rfl) (λ _ _, rfl)
instance [add_group α] : add_group αᵐᵒᵖ :=
unop_injective.add_group _ rfl (λ _ _, rfl) (λ _, rfl) (λ _ _, rfl) (λ _ _, rfl) (λ _ _, rfl)
instance [add_comm_group α] : add_comm_group αᵐᵒᵖ :=
unop_injective.add_comm_group _ rfl (λ _ _, rfl) (λ _, rfl) (λ _ _, rfl) (λ _ _, rfl) (λ _ _, rfl)
instance [add_group_with_one α] : add_group_with_one αᵐᵒᵖ :=
{ int_cast := λ n, op n,
int_cast_of_nat := λ n, show op ((n : ℤ) : α) = op n, by rw int.cast_coe_nat,
int_cast_neg_succ_of_nat := λ n, show op _ = op (- unop (op ((n + 1 : ℕ) : α))),
by erw [unop_op, int.cast_neg_succ_of_nat]; refl,
.. mul_opposite.add_monoid_with_one α, .. mul_opposite.add_group α }
instance [add_comm_group_with_one α] : add_comm_group_with_one αᵐᵒᵖ :=
{ .. mul_opposite.add_group_with_one α, ..mul_opposite.add_comm_group α }
/-!
### Multiplicative structures on `αᵐᵒᵖ`
We also generate additive structures on `αᵃᵒᵖ` using `to_additive`
-/
@[to_additive] instance [semigroup α] : semigroup αᵐᵒᵖ :=
{ mul_assoc := λ x y z, unop_injective $ eq.symm $ mul_assoc (unop z) (unop y) (unop x),
.. mul_opposite.has_mul α }
@[to_additive] instance [right_cancel_semigroup α] : left_cancel_semigroup αᵐᵒᵖ :=
{ mul_left_cancel := λ x y z H, unop_injective $ mul_right_cancel $ op_injective H,
.. mul_opposite.semigroup α }
@[to_additive] instance [left_cancel_semigroup α] : right_cancel_semigroup αᵐᵒᵖ :=
{ mul_right_cancel := λ x y z H, unop_injective $ mul_left_cancel $ op_injective H,
.. mul_opposite.semigroup α }
@[to_additive] instance [comm_semigroup α] : comm_semigroup αᵐᵒᵖ :=
{ mul_comm := λ x y, unop_injective $ mul_comm (unop y) (unop x),
.. mul_opposite.semigroup α }
@[to_additive] instance [mul_one_class α] : mul_one_class αᵐᵒᵖ :=
{ one_mul := λ x, unop_injective $ mul_one $ unop x,
mul_one := λ x, unop_injective $ one_mul $ unop x,
.. mul_opposite.has_mul α, .. mul_opposite.has_one α }
@[to_additive] instance [monoid α] : monoid αᵐᵒᵖ :=
{ npow := λ n x, op $ x.unop ^ n,
npow_zero' := λ x, unop_injective $ monoid.npow_zero' x.unop,
npow_succ' := λ n x, unop_injective $ pow_succ' x.unop n,
.. mul_opposite.semigroup α, .. mul_opposite.mul_one_class α }
@[to_additive] instance [right_cancel_monoid α] : left_cancel_monoid αᵐᵒᵖ :=
{ .. mul_opposite.left_cancel_semigroup α, .. mul_opposite.monoid α }
@[to_additive] instance [left_cancel_monoid α] : right_cancel_monoid αᵐᵒᵖ :=
{ .. mul_opposite.right_cancel_semigroup α, .. mul_opposite.monoid α }
@[to_additive] instance [cancel_monoid α] : cancel_monoid αᵐᵒᵖ :=
{ .. mul_opposite.right_cancel_monoid α, .. mul_opposite.left_cancel_monoid α }
@[to_additive] instance [comm_monoid α] : comm_monoid αᵐᵒᵖ :=
{ .. mul_opposite.monoid α, .. mul_opposite.comm_semigroup α }
@[to_additive] instance [cancel_comm_monoid α] : cancel_comm_monoid αᵐᵒᵖ :=
{ .. mul_opposite.cancel_monoid α, .. mul_opposite.comm_monoid α }
@[to_additive add_opposite.sub_neg_monoid] instance [div_inv_monoid α] : div_inv_monoid αᵐᵒᵖ :=
{ zpow := λ n x, op $ x.unop ^ n,
zpow_zero' := λ x, unop_injective $ div_inv_monoid.zpow_zero' x.unop,
zpow_succ' := λ n x, unop_injective $
by rw [unop_op, zpow_of_nat, zpow_of_nat, pow_succ', unop_mul, unop_op],
zpow_neg' := λ z x, unop_injective $ div_inv_monoid.zpow_neg' z x.unop,
.. mul_opposite.monoid α, .. mul_opposite.has_inv α }
@[to_additive add_opposite.subtraction_monoid] instance [division_monoid α] :
division_monoid αᵐᵒᵖ :=
{ mul_inv_rev := λ a b, unop_injective $ mul_inv_rev _ _,
inv_eq_of_mul := λ a b h, unop_injective $ inv_eq_of_mul_eq_one_left $ congr_arg unop h,
.. mul_opposite.div_inv_monoid α, .. mul_opposite.has_involutive_inv α }
@[to_additive add_opposite.subtraction_comm_monoid] instance [division_comm_monoid α] :
division_comm_monoid αᵐᵒᵖ :=
{ ..mul_opposite.division_monoid α, ..mul_opposite.comm_semigroup α }
@[to_additive] instance [group α] : group αᵐᵒᵖ :=
{ mul_left_inv := λ x, unop_injective $ mul_inv_self $ unop x,
.. mul_opposite.div_inv_monoid α, }
@[to_additive] instance [comm_group α] : comm_group αᵐᵒᵖ :=
{ .. mul_opposite.group α, .. mul_opposite.comm_monoid α }
variable {α}
@[simp, norm_cast, to_additive] lemma op_nat_cast [has_nat_cast α] (n : ℕ) : op (n : α) = n := rfl
@[simp, norm_cast, to_additive] lemma op_int_cast [has_int_cast α] (n : ℤ) : op (n : α) = n := rfl
@[simp, norm_cast, to_additive]
lemma unop_nat_cast [has_nat_cast α] (n : ℕ) : unop (n : αᵐᵒᵖ) = n := rfl
@[simp, norm_cast, to_additive]
lemma unop_int_cast [has_int_cast α] (n : ℤ) : unop (n : αᵐᵒᵖ) = n := rfl
@[simp, to_additive] lemma unop_div [div_inv_monoid α] (x y : αᵐᵒᵖ) :
unop (x / y) = (unop y)⁻¹ * unop x :=
rfl
@[simp, to_additive] lemma op_div [div_inv_monoid α] (x y : α) :
op (x / y) = (op y)⁻¹ * op x :=
by simp [div_eq_mul_inv]
@[simp, to_additive] lemma semiconj_by_op [has_mul α] {a x y : α} :
semiconj_by (op a) (op y) (op x) ↔ semiconj_by a x y :=
by simp only [semiconj_by, ← op_mul, op_inj, eq_comm]
@[simp, to_additive] lemma semiconj_by_unop [has_mul α] {a x y : αᵐᵒᵖ} :
semiconj_by (unop a) (unop y) (unop x) ↔ semiconj_by a x y :=
by conv_rhs { rw [← op_unop a, ← op_unop x, ← op_unop y, semiconj_by_op] }
@[to_additive] lemma _root_.semiconj_by.op [has_mul α] {a x y : α} (h : semiconj_by a x y) :
semiconj_by (op a) (op y) (op x) :=
semiconj_by_op.2 h
@[to_additive] lemma _root_.semiconj_by.unop [has_mul α] {a x y : αᵐᵒᵖ} (h : semiconj_by a x y) :
semiconj_by (unop a) (unop y) (unop x) :=
semiconj_by_unop.2 h
@[to_additive] lemma _root_.commute.op [has_mul α] {x y : α} (h : commute x y) :
commute (op x) (op y) := h.op
@[to_additive] lemma commute.unop [has_mul α] {x y : αᵐᵒᵖ} (h : commute x y) :
commute (unop x) (unop y) := h.unop
@[simp, to_additive] lemma commute_op [has_mul α] {x y : α} :
commute (op x) (op y) ↔ commute x y :=
semiconj_by_op
@[simp, to_additive] lemma commute_unop [has_mul α] {x y : αᵐᵒᵖ} :
commute (unop x) (unop y) ↔ commute x y :=
semiconj_by_unop
/-- The function `mul_opposite.op` is an additive equivalence. -/
@[simps { fully_applied := ff, simp_rhs := tt }]
def op_add_equiv [has_add α] : α ≃+ αᵐᵒᵖ :=
{ map_add' := λ a b, rfl, .. op_equiv }
@[simp] lemma op_add_equiv_to_equiv [has_add α] :
(op_add_equiv : α ≃+ αᵐᵒᵖ).to_equiv = op_equiv :=
rfl
end mul_opposite
/-!
### Multiplicative structures on `αᵃᵒᵖ`
-/
namespace add_opposite
instance [semigroup α] : semigroup (αᵃᵒᵖ) :=
unop_injective.semigroup _ (λ x y, rfl)
instance [left_cancel_semigroup α] : left_cancel_semigroup αᵃᵒᵖ :=
unop_injective.left_cancel_semigroup _ (λ x y, rfl)
instance [right_cancel_semigroup α] : right_cancel_semigroup αᵃᵒᵖ :=
unop_injective.right_cancel_semigroup _ (λ x y, rfl)
instance [comm_semigroup α] : comm_semigroup αᵃᵒᵖ :=
unop_injective.comm_semigroup _ (λ x y, rfl)
instance [mul_one_class α] : mul_one_class αᵃᵒᵖ :=
unop_injective.mul_one_class _ rfl (λ x y, rfl)
instance {β} [has_pow α β] : has_pow αᵃᵒᵖ β := { pow := λ a b, op (unop a ^ b) }
@[simp] lemma op_pow {β} [has_pow α β] (a : α) (b : β) : op (a ^ b) = op a ^ b := rfl
@[simp] lemma unop_pow {β} [has_pow α β] (a : αᵃᵒᵖ) (b : β) : unop (a ^ b) = unop a ^ b := rfl
instance [monoid α] : monoid αᵃᵒᵖ :=
unop_injective.monoid _ rfl (λ _ _, rfl) (λ _ _, rfl)
instance [comm_monoid α] : comm_monoid αᵃᵒᵖ :=
unop_injective.comm_monoid _ rfl (λ _ _, rfl) (λ _ _, rfl)
instance [div_inv_monoid α] : div_inv_monoid αᵃᵒᵖ :=
unop_injective.div_inv_monoid _ rfl (λ _ _, rfl) (λ _, rfl) (λ _ _, rfl) (λ _ _, rfl) (λ _ _, rfl)
instance [group α] : group αᵃᵒᵖ :=
unop_injective.group _ rfl (λ _ _, rfl) (λ _, rfl) (λ _ _, rfl) (λ _ _, rfl) (λ _ _, rfl)
instance [comm_group α] : comm_group αᵃᵒᵖ :=
unop_injective.comm_group _ rfl (λ _ _, rfl) (λ _, rfl) (λ _ _, rfl) (λ _ _, rfl) (λ _ _, rfl)
-- NOTE: `add_monoid_with_one α → add_monoid_with_one αᵃᵒᵖ` does not hold
instance [add_comm_monoid_with_one α] : add_comm_monoid_with_one αᵃᵒᵖ :=
{ nat_cast_zero := show op ((0 : ℕ) : α) = 0, by rw [nat.cast_zero, op_zero],
nat_cast_succ := show ∀ n, op ((n + 1 : ℕ) : α) = op (n : ℕ) + 1, by simp [add_comm],
..add_opposite.add_comm_monoid α, ..add_opposite.has_one, ..add_opposite.has_nat_cast _ }
instance [add_comm_group_with_one α] : add_comm_group_with_one αᵃᵒᵖ :=
{ int_cast_of_nat := λ n, congr_arg op $ int.cast_of_nat n,
int_cast_neg_succ_of_nat := λ _, congr_arg op $ int.cast_neg_succ_of_nat _,
..add_opposite.add_comm_monoid_with_one _, ..add_opposite.add_comm_group α,
..add_opposite.has_int_cast α }
variable {α}
/-- The function `add_opposite.op` is a multiplicative equivalence. -/
@[simps { fully_applied := ff, simp_rhs := tt }]
def op_mul_equiv [has_mul α] : α ≃* αᵃᵒᵖ :=
{ map_mul' := λ a b, rfl, .. op_equiv }
@[simp] lemma op_mul_equiv_to_equiv [has_mul α] :
(op_mul_equiv : α ≃* αᵃᵒᵖ).to_equiv = op_equiv :=
rfl
end add_opposite
open mul_opposite
/-- Inversion on a group is a `mul_equiv` to the opposite group. When `G` is commutative, there is
`mul_equiv.inv`. -/
@[to_additive "Negation on an additive group is an `add_equiv` to the opposite group. When `G`
is commutative, there is `add_equiv.inv`.", simps { fully_applied := ff, simp_rhs := tt }]
def mul_equiv.inv' (G : Type*) [division_monoid G] : G ≃* Gᵐᵒᵖ :=
{ map_mul' := λ x y, unop_injective $ mul_inv_rev x y,
.. (equiv.inv G).trans op_equiv }
/-- A semigroup homomorphism `f : M →ₙ* N` such that `f x` commutes with `f y` for all `x, y`
defines a semigroup homomorphism to `Nᵐᵒᵖ`. -/
@[to_additive "An additive semigroup homomorphism `f : add_hom M N` such that `f x` additively
commutes with `f y` for all `x, y` defines an additive semigroup homomorphism to `Sᵃᵒᵖ`.",
simps {fully_applied := ff}]
def mul_hom.to_opposite {M N : Type*} [has_mul M] [has_mul N] (f : M →ₙ* N)
(hf : ∀ x y, commute (f x) (f y)) : M →ₙ* Nᵐᵒᵖ :=
{ to_fun := mul_opposite.op ∘ f,
map_mul' := λ x y, by simp [(hf x y).eq] }
/-- A semigroup homomorphism `f : M →ₙ* N` such that `f x` commutes with `f y` for all `x, y`
defines a semigroup homomorphism from `Mᵐᵒᵖ`. -/
@[to_additive "An additive semigroup homomorphism `f : add_hom M N` such that `f x` additively
commutes with `f y` for all `x`, `y` defines an additive semigroup homomorphism from `Mᵃᵒᵖ`.",
simps {fully_applied := ff}]
def mul_hom.from_opposite {M N : Type*} [has_mul M] [has_mul N] (f : M →ₙ* N)
(hf : ∀ x y, commute (f x) (f y)) : Mᵐᵒᵖ →ₙ* N :=
{ to_fun := f ∘ mul_opposite.unop,
map_mul' := λ x y, (f.map_mul _ _).trans (hf _ _).eq }
/-- A monoid homomorphism `f : M →* N` such that `f x` commutes with `f y` for all `x, y` defines
a monoid homomorphism to `Nᵐᵒᵖ`. -/
@[to_additive "An additive monoid homomorphism `f : M →+ N` such that `f x` additively commutes
with `f y` for all `x, y` defines an additive monoid homomorphism to `Sᵃᵒᵖ`.",
simps {fully_applied := ff}]
def monoid_hom.to_opposite {M N : Type*} [mul_one_class M] [mul_one_class N] (f : M →* N)
(hf : ∀ x y, commute (f x) (f y)) : M →* Nᵐᵒᵖ :=
{ to_fun := mul_opposite.op ∘ f,
map_one' := congr_arg op f.map_one,
map_mul' := λ x y, by simp [(hf x y).eq] }
/-- A monoid homomorphism `f : M →* N` such that `f x` commutes with `f y` for all `x, y` defines
a monoid homomorphism from `Mᵐᵒᵖ`. -/
@[to_additive "An additive monoid homomorphism `f : M →+ N` such that `f x` additively commutes
with `f y` for all `x`, `y` defines an additive monoid homomorphism from `Mᵃᵒᵖ`.",
simps {fully_applied := ff}]
def monoid_hom.from_opposite {M N : Type*} [mul_one_class M] [mul_one_class N] (f : M →* N)
(hf : ∀ x y, commute (f x) (f y)) : Mᵐᵒᵖ →* N :=
{ to_fun := f ∘ mul_opposite.unop,
map_one' := f.map_one,
map_mul' := λ x y, (f.map_mul _ _).trans (hf _ _).eq }
/-- The units of the opposites are equivalent to the opposites of the units. -/
@[to_additive "The additive units of the additive opposites are equivalent to the additive opposites
of the additive units."]
def units.op_equiv {M} [monoid M] : (Mᵐᵒᵖ)ˣ ≃* (Mˣ)ᵐᵒᵖ :=
{ to_fun := λ u, op ⟨unop u, unop ↑(u⁻¹), op_injective u.4, op_injective u.3⟩,
inv_fun := mul_opposite.rec $ λ u, ⟨op ↑(u), op ↑(u⁻¹), unop_injective $ u.4, unop_injective u.3⟩,
map_mul' := λ x y, unop_injective $ units.ext $ rfl,
left_inv := λ x, units.ext $ by simp,
right_inv := λ x, unop_injective $ units.ext $ rfl }
@[simp, to_additive]
lemma units.coe_unop_op_equiv {M} [monoid M] (u : (Mᵐᵒᵖ)ˣ) :
((units.op_equiv u).unop : M) = unop (u : Mᵐᵒᵖ) :=
rfl
@[simp, to_additive]
lemma units.coe_op_equiv_symm {M} [monoid M] (u : (Mˣ)ᵐᵒᵖ) :
(units.op_equiv.symm u : Mᵐᵒᵖ) = op (u.unop : M) :=
rfl
/-- A semigroup homomorphism `M →ₙ* N` can equivalently be viewed as a semigroup homomorphism
`Mᵐᵒᵖ →ₙ* Nᵐᵒᵖ`. This is the action of the (fully faithful) `ᵐᵒᵖ`-functor on morphisms. -/
@[to_additive "An additive semigroup homomorphism `add_hom M N` can equivalently be viewed as an
additive semigroup homomorphism `add_hom Mᵃᵒᵖ Nᵃᵒᵖ`. This is the action of the (fully faithful)
`ᵃᵒᵖ`-functor on morphisms.", simps]
def mul_hom.op {M N} [has_mul M] [has_mul N] :
(M →ₙ* N) ≃ (Mᵐᵒᵖ →ₙ* Nᵐᵒᵖ) :=
{ to_fun := λ f, { to_fun := op ∘ f ∘ unop,
map_mul' := λ x y, unop_injective (f.map_mul y.unop x.unop) },
inv_fun := λ f, { to_fun := unop ∘ f ∘ op,
map_mul' := λ x y, congr_arg unop (f.map_mul (op y) (op x)) },
left_inv := λ f, by { ext, refl },
right_inv := λ f, by { ext x, simp } }
/-- The 'unopposite' of a semigroup homomorphism `Mᵐᵒᵖ →ₙ* Nᵐᵒᵖ`. Inverse to `mul_hom.op`. -/
@[simp, to_additive "The 'unopposite' of an additive semigroup homomorphism `Mᵃᵒᵖ →ₙ+ Nᵃᵒᵖ`. Inverse
to `add_hom.op`."]
def mul_hom.unop {M N} [has_mul M] [has_mul N] :
(Mᵐᵒᵖ →ₙ* Nᵐᵒᵖ) ≃ (M →ₙ* N) := mul_hom.op.symm
/-- An additive semigroup homomorphism `add_hom M N` can equivalently be viewed as an additive
homomorphism `add_hom Mᵐᵒᵖ Nᵐᵒᵖ`. This is the action of the (fully faithful) `ᵐᵒᵖ`-functor on
morphisms. -/
@[simps]
def add_hom.mul_op {M N} [has_add M] [has_add N] :
(add_hom M N) ≃ (add_hom Mᵐᵒᵖ Nᵐᵒᵖ) :=
{ to_fun := λ f, { to_fun := op ∘ f ∘ unop,
map_add' := λ x y, unop_injective (f.map_add x.unop y.unop) },
inv_fun := λ f, { to_fun := unop ∘ f ∘ op,
map_add' := λ x y, congr_arg unop (f.map_add (op x) (op y)) },
left_inv := λ f, by { ext, refl },
right_inv := λ f, by { ext, simp } }
/-- The 'unopposite' of an additive semigroup hom `αᵐᵒᵖ →+ βᵐᵒᵖ`. Inverse to
`add_hom.mul_op`. -/
@[simp] def add_hom.mul_unop {α β} [has_add α] [has_add β] :
(add_hom αᵐᵒᵖ βᵐᵒᵖ) ≃ (add_hom α β) := add_hom.mul_op.symm
/-- A monoid homomorphism `M →* N` can equivalently be viewed as a monoid homomorphism
`Mᵐᵒᵖ →* Nᵐᵒᵖ`. This is the action of the (fully faithful) `ᵐᵒᵖ`-functor on morphisms. -/
@[to_additive "An additive monoid homomorphism `M →+ N` can equivalently be viewed as an
additive monoid homomorphism `Mᵃᵒᵖ →+ Nᵃᵒᵖ`. This is the action of the (fully faithful)
`ᵃᵒᵖ`-functor on morphisms.", simps]
def monoid_hom.op {M N} [mul_one_class M] [mul_one_class N] :
(M →* N) ≃ (Mᵐᵒᵖ →* Nᵐᵒᵖ) :=
{ to_fun := λ f, { to_fun := op ∘ f ∘ unop,
map_one' := congr_arg op f.map_one,
map_mul' := λ x y, unop_injective (f.map_mul y.unop x.unop) },
inv_fun := λ f, { to_fun := unop ∘ f ∘ op,
map_one' := congr_arg unop f.map_one,
map_mul' := λ x y, congr_arg unop (f.map_mul (op y) (op x)) },
left_inv := λ f, by { ext, refl },
right_inv := λ f, by { ext x, simp } }
/-- The 'unopposite' of a monoid homomorphism `Mᵐᵒᵖ →* Nᵐᵒᵖ`. Inverse to `monoid_hom.op`. -/
@[simp, to_additive "The 'unopposite' of an additive monoid homomorphism `Mᵃᵒᵖ →+ Nᵃᵒᵖ`. Inverse to
`add_monoid_hom.op`."]
def monoid_hom.unop {M N} [mul_one_class M] [mul_one_class N] :
(Mᵐᵒᵖ →* Nᵐᵒᵖ) ≃ (M →* N) := monoid_hom.op.symm
/-- An additive homomorphism `M →+ N` can equivalently be viewed as an additive homomorphism
`Mᵐᵒᵖ →+ Nᵐᵒᵖ`. This is the action of the (fully faithful) `ᵐᵒᵖ`-functor on morphisms. -/
@[simps]
def add_monoid_hom.mul_op {M N} [add_zero_class M] [add_zero_class N] :
(M →+ N) ≃ (Mᵐᵒᵖ →+ Nᵐᵒᵖ) :=
{ to_fun := λ f, { to_fun := op ∘ f ∘ unop,
map_zero' := unop_injective f.map_zero,
map_add' := λ x y, unop_injective (f.map_add x.unop y.unop) },
inv_fun := λ f, { to_fun := unop ∘ f ∘ op,
map_zero' := congr_arg unop f.map_zero,
map_add' := λ x y, congr_arg unop (f.map_add (op x) (op y)) },
left_inv := λ f, by { ext, refl },
right_inv := λ f, by { ext, simp } }
/-- The 'unopposite' of an additive monoid hom `αᵐᵒᵖ →+ βᵐᵒᵖ`. Inverse to
`add_monoid_hom.mul_op`. -/
@[simp] def add_monoid_hom.mul_unop {α β} [add_zero_class α] [add_zero_class β] :
(αᵐᵒᵖ →+ βᵐᵒᵖ) ≃ (α →+ β) := add_monoid_hom.mul_op.symm
/-- A iso `α ≃+ β` can equivalently be viewed as an iso `αᵐᵒᵖ ≃+ βᵐᵒᵖ`. -/
@[simps]
def add_equiv.mul_op {α β} [has_add α] [has_add β] :
(α ≃+ β) ≃ (αᵐᵒᵖ ≃+ βᵐᵒᵖ) :=
{ to_fun := λ f, op_add_equiv.symm.trans (f.trans op_add_equiv),
inv_fun := λ f, op_add_equiv.trans (f.trans op_add_equiv.symm),
left_inv := λ f, by { ext, refl },
right_inv := λ f, by { ext, simp } }
/-- The 'unopposite' of an iso `αᵐᵒᵖ ≃+ βᵐᵒᵖ`. Inverse to `add_equiv.mul_op`. -/
@[simp] def add_equiv.mul_unop {α β} [has_add α] [has_add β] :
(αᵐᵒᵖ ≃+ βᵐᵒᵖ) ≃ (α ≃+ β) := add_equiv.mul_op.symm
/-- A iso `α ≃* β` can equivalently be viewed as an iso `αᵐᵒᵖ ≃* βᵐᵒᵖ`. -/
@[to_additive "A iso `α ≃+ β` can equivalently be viewed as an iso `αᵃᵒᵖ ≃+ βᵃᵒᵖ`.", simps]
def mul_equiv.op {α β} [has_mul α] [has_mul β] :
(α ≃* β) ≃ (αᵐᵒᵖ ≃* βᵐᵒᵖ) :=
{ to_fun := λ f, { to_fun := op ∘ f ∘ unop,
inv_fun := op ∘ f.symm ∘ unop,
left_inv := λ x, unop_injective (f.symm_apply_apply x.unop),
right_inv := λ x, unop_injective (f.apply_symm_apply x.unop),
map_mul' := λ x y, unop_injective (f.map_mul y.unop x.unop) },
inv_fun := λ f, { to_fun := unop ∘ f ∘ op,
inv_fun := unop ∘ f.symm ∘ op,
left_inv := λ x, by simp,
right_inv := λ x, by simp,
map_mul' := λ x y, congr_arg unop (f.map_mul (op y) (op x)) },
left_inv := λ f, by { ext, refl },
right_inv := λ f, by { ext, simp } }
/-- The 'unopposite' of an iso `αᵐᵒᵖ ≃* βᵐᵒᵖ`. Inverse to `mul_equiv.op`. -/
@[simp, to_additive "The 'unopposite' of an iso `αᵃᵒᵖ ≃+ βᵃᵒᵖ`. Inverse to `add_equiv.op`."]
def mul_equiv.unop {α β} [has_mul α] [has_mul β] :
(αᵐᵒᵖ ≃* βᵐᵒᵖ) ≃ (α ≃* β) := mul_equiv.op.symm
section ext
/-- This ext lemma change equalities on `αᵐᵒᵖ →+ β` to equalities on `α →+ β`.
This is useful because there are often ext lemmas for specific `α`s that will apply
to an equality of `α →+ β` such as `finsupp.add_hom_ext'`. -/
@[ext]
lemma add_monoid_hom.mul_op_ext {α β} [add_zero_class α] [add_zero_class β]
(f g : αᵐᵒᵖ →+ β)
(h : f.comp (op_add_equiv : α ≃+ αᵐᵒᵖ).to_add_monoid_hom =
g.comp (op_add_equiv : α ≃+ αᵐᵒᵖ).to_add_monoid_hom) : f = g :=
add_monoid_hom.ext $ mul_opposite.rec $ λ x, (add_monoid_hom.congr_fun h : _) x
end ext
|
5e02162c1c6b63d116bc9cdbf76f1518f1a57c52 | 690889011852559ee5ac4dfea77092de8c832e7e | /src/data/string/defs.lean | 5df64b9941a586cae03f2cc86b37f4f7d001762d | [
"Apache-2.0"
] | permissive | williamdemeo/mathlib | f6df180148f8acc91de9ba5e558976ab40a872c7 | 1fa03c29f9f273203bbffb79d10d31f696b3d317 | refs/heads/master | 1,584,785,260,929 | 1,572,195,914,000 | 1,572,195,913,000 | 138,435,193 | 0 | 0 | Apache-2.0 | 1,529,789,739,000 | 1,529,789,739,000 | null | UTF-8 | Lean | false | false | 754 | lean | import data.list.defs
namespace string
def map_tokens (c : char) (f : list string → list string) : string → string :=
intercalate (singleton c) ∘ f ∘ split (= c)
def over_list (f : list char → list char) : string → string :=
list.as_string ∘ f ∘ string.to_list
def split_on (c : char) (s : string) : list string :=
(s.to_list.split_on c).map list.as_string
/-- Tests whether the first string is a prefix of the second string -/
def is_prefix_of (x y : string) : bool :=
x.to_list.is_prefix_of y.to_list
def is_suffix_of (x y : string) : bool :=
x.to_list.is_suffix_of y.to_list
/-- Removes the first `n` elements from the string `s` -/
def popn (s : string) (n : nat) : string :=
(s.mk_iterator.nextn n).next_to_string
end string
|
3137cf1401113788f900a3a8dec87a88ead92846 | b147e1312077cdcfea8e6756207b3fa538982e12 | /data/set/basic.lean | ce63360416513c60fbf1b5cffde00c8f91756249 | [
"Apache-2.0"
] | permissive | SzJS/mathlib | 07836ee708ca27cd18347e1e11ce7dd5afb3e926 | 23a5591fca0d43ee5d49d89f6f0ee07a24a6ca29 | refs/heads/master | 1,584,980,332,064 | 1,532,063,841,000 | 1,532,063,841,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 38,529 | 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
-/
import tactic.ext tactic.finish data.subtype
open function
namespace set
universes u v w x
variables {α : Type u} {β : Type v} {γ : Type w} {ι : Sort x} {a : α} {s t : set α}
instance : inhabited (set α) := ⟨∅⟩
@[extensionality]
theorem ext {a b : set α} (h : ∀ x, x ∈ a ↔ x ∈ b) : a = b :=
funext (assume x, propext (h x))
theorem ext_iff (s t : set α) : s = t ↔ ∀ x, x ∈ s ↔ x ∈ t :=
⟨begin intros h x, rw h end, set.ext⟩
@[trans] theorem mem_of_mem_of_subset {α : Type u} {x : α} {s t : set α} (hx : x ∈ s) (h : s ⊆ t) : x ∈ t :=
h hx
/- mem and set_of -/
@[simp] theorem mem_set_of_eq {a : α} {p : α → Prop} : a ∈ {a | p a} = p a := rfl
@[simp] theorem nmem_set_of_eq {a : α} {P : α → Prop} : a ∉ {a : α | P a} = ¬ P a := rfl
@[simp] theorem set_of_mem_eq {s : set α} : {x | x ∈ s} = s := rfl
theorem mem_def {a : α} {s : set α} : a ∈ s ↔ s a := iff.rfl
instance decidable_mem (s : set α) [H : decidable_pred s] : ∀ a, decidable (a ∈ s) := H
instance decidable_set_of (p : α → Prop) [H : decidable_pred p] : decidable_pred {a | p a} := H
@[simp] theorem set_of_subset_set_of {p q : α → Prop} : {a | p a} ⊆ {a | q a} ↔ (∀a, p a → q a) := iff.rfl
/- set coercion to a type -/
instance : has_coe_to_sort (set α) := ⟨_, λ s, {x // x ∈ s}⟩
@[simp] theorem set_coe_eq_subtype (s : set α) : coe_sort.{(u+1) (u+2)} s = {x // x ∈ s} := rfl
@[simp] theorem set_coe.forall {s : set α} {p : s → Prop} :
(∀ x : s, p x) ↔ (∀ x (h : x ∈ s), p ⟨x, h⟩) :=
subtype.forall
@[simp] theorem set_coe.exists {s : set α} {p : s → Prop} :
(∃ x : s, p x) ↔ (∃ x (h : x ∈ s), p ⟨x, h⟩) :=
subtype.exists
@[simp] theorem set_coe_cast : ∀ {s t : set α} (H' : s = t) (H : @eq (Type u) s t) (x : s),
cast H x = ⟨x.1, H' ▸ x.2⟩
| s _ rfl _ ⟨x, h⟩ := rfl
/- subset -/
-- TODO(Jeremy): write a tactic to unfold specific instances of generic notation?
theorem subset_def {s t : set α} : (s ⊆ t) = ∀ x, x ∈ s → x ∈ t := rfl
@[refl] theorem subset.refl (a : set α) : a ⊆ a := assume x, id
@[trans] theorem subset.trans {a b c : set α} (ab : a ⊆ b) (bc : b ⊆ c) : a ⊆ c :=
assume x h, bc (ab h)
@[trans] theorem mem_of_eq_of_mem {α : Type u} {x y : α} {s : set α} (hx : x = y) (h : y ∈ s) : x ∈ s :=
hx.symm ▸ h
theorem 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))
theorem subset.antisymm_iff {a b : set α} : a = b ↔ a ⊆ b ∧ b ⊆ a :=
⟨λ e, e ▸ ⟨subset.refl _, subset.refl _⟩,
λ ⟨h₁, h₂⟩, subset.antisymm h₁ h₂⟩
-- an alterantive name
theorem eq_of_subset_of_subset {a b : set α} (h₁ : a ⊆ b) (h₂ : b ⊆ a) : a = b :=
subset.antisymm h₁ h₂
theorem mem_of_subset_of_mem {s₁ s₂ : set α} {a : α} : s₁ ⊆ s₂ → a ∈ s₁ → a ∈ s₂ :=
assume h₁ h₂, h₁ h₂
theorem not_subset : (¬ s ⊆ t) ↔ ∃a, a ∈ s ∧ a ∉ t :=
by simp [subset_def, classical.not_forall]
/- strict subset -/
/-- `s ⊂ t` means that `s` is a strict subset of `t`, that is, `s ⊆ t` but `s ≠ t`. -/
def strict_subset (s t : set α) := s ⊆ t ∧ s ≠ t
instance : has_ssubset (set α) := ⟨strict_subset⟩
theorem ssubset_def : (s ⊂ t) = (s ⊆ t ∧ s ≠ t) := rfl
lemma exists_of_ssubset {α : Type u} {s t : set α} (h : s ⊂ t) : (∃x∈t, x ∉ s) :=
classical.by_contradiction $ assume hn,
have t ⊆ s, from assume a hat, classical.by_contradiction $ assume has, hn ⟨a, hat, has⟩,
h.2 $ subset.antisymm h.1 this
theorem not_mem_empty (x : α) : ¬ (x ∈ (∅ : set α)) :=
assume h : x ∈ ∅, h
@[simp] theorem not_not_mem [decidable (a ∈ s)] : ¬ (a ∉ s) ↔ a ∈ s :=
not_not
/- empty set -/
theorem empty_def : (∅ : set α) = {x | false} := rfl
@[simp] theorem mem_empty_eq (x : α) : x ∈ (∅ : set α) = false := rfl
@[simp] theorem set_of_false : {a : α | false} = ∅ := rfl
theorem eq_empty_iff_forall_not_mem {s : set α} : s = ∅ ↔ ∀ x, x ∉ s :=
by simp [ext_iff]
theorem ne_empty_of_mem {s : set α} {x : α} (h : x ∈ s) : s ≠ ∅ :=
by { intro hs, rewrite hs at h, apply not_mem_empty _ h }
@[simp] theorem empty_subset (s : set α) : ∅ ⊆ s :=
assume x, assume h, false.elim h
theorem subset_empty_iff {s : set α} : s ⊆ ∅ ↔ s = ∅ :=
by simp [subset.antisymm_iff]
theorem eq_empty_of_subset_empty {s : set α} : s ⊆ ∅ → s = ∅ :=
subset_empty_iff.1
theorem ne_empty_iff_exists_mem {s : set α} : s ≠ ∅ ↔ ∃ x, x ∈ s :=
by haveI := classical.prop_decidable;
simp [eq_empty_iff_forall_not_mem]
theorem exists_mem_of_ne_empty {s : set α} : s ≠ ∅ → ∃ x, x ∈ s :=
ne_empty_iff_exists_mem.1
-- TODO: remove when simplifier stops rewriting `a ≠ b` to `¬ a = b`
theorem not_eq_empty_iff_exists {s : set α} : ¬ (s = ∅) ↔ ∃ x, x ∈ s :=
ne_empty_iff_exists_mem
theorem subset_eq_empty {s t : set α} (h : t ⊆ s) (e : s = ∅) : t = ∅ :=
subset_empty_iff.1 $ e ▸ h
theorem subset_ne_empty {s t : set α} (h : t ⊆ s) : t ≠ ∅ → s ≠ ∅ :=
mt (subset_eq_empty h)
theorem ball_empty_iff {p : α → Prop} :
(∀ x ∈ (∅ : set α), p x) ↔ true :=
by simp [iff_def]
/- universal set -/
theorem univ_def : @univ α = {x | true} := rfl
@[simp] theorem mem_univ (x : α) : x ∈ @univ α := trivial
theorem empty_ne_univ [h : inhabited α] : (∅ : set α) ≠ univ :=
by simp [ext_iff]
@[simp] theorem subset_univ (s : set α) : s ⊆ univ := λ x H, trivial
theorem univ_subset_iff {s : set α} : univ ⊆ s ↔ s = univ :=
by simp [subset.antisymm_iff]
theorem eq_univ_of_univ_subset {s : set α} : univ ⊆ s → s = univ :=
univ_subset_iff.1
theorem eq_univ_iff_forall {s : set α} : s = univ ↔ ∀ x, x ∈ s :=
by simp [ext_iff]
theorem eq_univ_of_forall {s : set α} : (∀ x, x ∈ s) → s = univ := eq_univ_iff_forall.2
/- union -/
theorem union_def {s₁ s₂ : set α} : s₁ ∪ s₂ = {a | a ∈ s₁ ∨ a ∈ s₂} := rfl
theorem mem_union_left {x : α} {a : set α} (b : set α) : x ∈ a → x ∈ a ∪ b := or.inl
theorem mem_union_right {x : α} {b : set α} (a : set α) : x ∈ b → x ∈ a ∪ b := or.inr
theorem mem_or_mem_of_mem_union {x : α} {a b : set α} (H : x ∈ a ∪ b) : x ∈ a ∨ x ∈ b := H
theorem mem_union.elim {x : α} {a b : set α} {P : Prop}
(H₁ : x ∈ a ∪ b) (H₂ : x ∈ a → P) (H₃ : x ∈ b → P) : P :=
or.elim H₁ H₂ H₃
theorem mem_union (x : α) (a b : set α) : x ∈ a ∪ b ↔ x ∈ a ∨ x ∈ b := iff.rfl
@[simp] theorem mem_union_eq (x : α) (a b : set α) : x ∈ a ∪ b = (x ∈ a ∨ x ∈ b) := rfl
@[simp] theorem union_self (a : set α) : a ∪ a = a :=
ext (assume x, or_self _)
@[simp] theorem union_empty (a : set α) : a ∪ ∅ = a :=
ext (assume x, or_false _)
@[simp] theorem empty_union (a : set α) : ∅ ∪ a = a :=
ext (assume x, false_or _)
theorem union_comm (a b : set α) : a ∪ b = b ∪ a :=
ext (assume x, or.comm)
theorem union_assoc (a b c : set α) : (a ∪ b) ∪ c = a ∪ (b ∪ c) :=
ext (assume x, or.assoc)
instance union_is_assoc : is_associative (set α) (∪) :=
⟨union_assoc⟩
instance union_is_comm : is_commutative (set α) (∪) :=
⟨union_comm⟩
theorem union_left_comm (s₁ s₂ s₃ : set α) : s₁ ∪ (s₂ ∪ s₃) = s₂ ∪ (s₁ ∪ s₃) :=
by finish
theorem union_right_comm (s₁ s₂ s₃ : set α) : (s₁ ∪ s₂) ∪ s₃ = (s₁ ∪ s₃) ∪ s₂ :=
by finish
theorem union_eq_self_of_subset_left {s t : set α} (h : s ⊆ t) : s ∪ t = t :=
by finish [subset_def, ext_iff, iff_def]
theorem union_eq_self_of_subset_right {s t : set α} (h : t ⊆ s) : s ∪ t = s :=
by finish [subset_def, ext_iff, iff_def]
@[simp] theorem subset_union_left (s t : set α) : s ⊆ s ∪ t := λ x, or.inl
@[simp] theorem subset_union_right (s t : set α) : t ⊆ s ∪ t := λ x, or.inr
theorem union_subset {s t r : set α} (sr : s ⊆ r) (tr : t ⊆ r) : s ∪ t ⊆ r :=
by finish [subset_def, union_def]
@[simp] theorem union_subset_iff {s t u : set α} : s ∪ t ⊆ u ↔ s ⊆ u ∧ t ⊆ u :=
by finish [iff_def, subset_def]
theorem union_subset_union {s₁ s₂ t₁ t₂ : set α} (h₁ : s₁ ⊆ s₂) (h₂ : t₁ ⊆ t₂) : s₁ ∪ t₁ ⊆ s₂ ∪ t₂ :=
by finish [subset_def]
theorem union_subset_union_left {s₁ s₂ : set α} (t) (h : s₁ ⊆ s₂) : s₁ ∪ t ⊆ s₂ ∪ t :=
union_subset_union h (by refl)
theorem union_subset_union_right (s) {t₁ t₂ : set α} (h : t₁ ⊆ t₂) : s ∪ t₁ ⊆ s ∪ t₂ :=
union_subset_union (by refl) h
@[simp] theorem union_empty_iff {s t : set α} : s ∪ t = ∅ ↔ s = ∅ ∧ t = ∅ :=
⟨by finish [ext_iff], by finish [ext_iff]⟩
/- intersection -/
theorem inter_def {s₁ s₂ : set α} : s₁ ∩ s₂ = {a | a ∈ s₁ ∧ a ∈ s₂} := rfl
theorem mem_inter_iff (x : α) (a b : set α) : x ∈ a ∩ b ↔ x ∈ a ∧ x ∈ b := iff.rfl
@[simp] theorem mem_inter_eq (x : α) (a b : set α) : x ∈ a ∩ b = (x ∈ a ∧ x ∈ b) := rfl
theorem mem_inter {x : α} {a b : set α} (ha : x ∈ a) (hb : x ∈ b) : x ∈ a ∩ b :=
⟨ha, hb⟩
theorem mem_of_mem_inter_left {x : α} {a b : set α} (h : x ∈ a ∩ b) : x ∈ a :=
h.left
theorem mem_of_mem_inter_right {x : α} {a b : set α} (h : x ∈ a ∩ b) : x ∈ b :=
h.right
@[simp] theorem inter_self (a : set α) : a ∩ a = a :=
ext (assume x, and_self _)
@[simp] theorem inter_empty (a : set α) : a ∩ ∅ = ∅ :=
ext (assume x, and_false _)
@[simp] theorem empty_inter (a : set α) : ∅ ∩ a = ∅ :=
ext (assume x, false_and _)
theorem inter_comm (a b : set α) : a ∩ b = b ∩ a :=
ext (assume x, and.comm)
theorem inter_assoc (a b c : set α) : (a ∩ b) ∩ c = a ∩ (b ∩ c) :=
ext (assume x, and.assoc)
instance inter_is_assoc : is_associative (set α) (∩) :=
⟨inter_assoc⟩
instance inter_is_comm : is_commutative (set α) (∩) :=
⟨inter_comm⟩
theorem inter_left_comm (s₁ s₂ s₃ : set α) : s₁ ∩ (s₂ ∩ s₃) = s₂ ∩ (s₁ ∩ s₃) :=
by finish
theorem inter_right_comm (s₁ s₂ s₃ : set α) : (s₁ ∩ s₂) ∩ s₃ = (s₁ ∩ s₃) ∩ s₂ :=
by finish
@[simp] theorem inter_subset_left (s t : set α) : s ∩ t ⊆ s := λ x H, and.left H
@[simp] theorem inter_subset_right (s t : set α) : s ∩ t ⊆ t := λ x H, and.right H
theorem subset_inter {s t r : set α} (rs : r ⊆ s) (rt : r ⊆ t) : r ⊆ s ∩ t :=
by finish [subset_def, inter_def]
@[simp] theorem subset_inter_iff {s t r : set α} : r ⊆ s ∩ t ↔ r ⊆ s ∧ r ⊆ t :=
⟨λ h, ⟨subset.trans h (inter_subset_left _ _), subset.trans h (inter_subset_right _ _)⟩,
λ ⟨h₁, h₂⟩, subset_inter h₁ h₂⟩
@[simp] theorem inter_univ (a : set α) : a ∩ univ = a :=
ext (assume x, and_true _)
@[simp] theorem univ_inter (a : set α) : univ ∩ a = a :=
ext (assume x, true_and _)
theorem inter_subset_inter_left {s t : set α} (u : set α) (H : s ⊆ t) : s ∩ u ⊆ t ∩ u :=
by finish [subset_def]
theorem inter_subset_inter_right {s t : set α} (u : set α) (H : s ⊆ t) : u ∩ s ⊆ u ∩ t :=
by finish [subset_def]
theorem inter_subset_inter {s₁ s₂ t₁ t₂ : set α} (h₁ : s₁ ⊆ t₁) (h₂ : s₂ ⊆ t₂) : s₁ ∩ s₂ ⊆ t₁ ∩ t₂ :=
by finish [subset_def]
theorem inter_eq_self_of_subset_left {s t : set α} (h : s ⊆ t) : s ∩ t = s :=
by finish [subset_def, ext_iff, iff_def]
theorem inter_eq_self_of_subset_right {s t : set α} (h : t ⊆ s) : s ∩ t = t :=
by finish [subset_def, ext_iff, iff_def]
theorem union_inter_cancel_left {s t : set α} (h : s ∩ t ⊆ ∅) : (s ∪ t) ∩ s = s :=
by finish [ext_iff, iff_def]
theorem union_inter_cancel_right {s t : set α} (h : s ∩ t ⊆ ∅) : (s ∪ t) ∩ t = t :=
by finish [ext_iff, iff_def]
-- TODO(Mario): remove?
theorem nonempty_of_inter_nonempty_right {s t : set α} (h : s ∩ t ≠ ∅) : t ≠ ∅ :=
by finish [ext_iff, iff_def]
theorem nonempty_of_inter_nonempty_left {s t : set α} (h : s ∩ t ≠ ∅) : s ≠ ∅ :=
by finish [ext_iff, iff_def]
/- distributivity laws -/
theorem inter_distrib_left (s t u : set α) : s ∩ (t ∪ u) = (s ∩ t) ∪ (s ∩ u) :=
ext (assume x, and_or_distrib_left)
theorem inter_distrib_right (s t u : set α) : (s ∪ t) ∩ u = (s ∩ u) ∪ (t ∩ u) :=
ext (assume x, or_and_distrib_right)
theorem union_distrib_left (s t u : set α) : s ∪ (t ∩ u) = (s ∪ t) ∩ (s ∪ u) :=
ext (assume x, or_and_distrib_left)
theorem union_distrib_right (s t u : set α) : (s ∩ t) ∪ u = (s ∪ u) ∩ (t ∪ u) :=
ext (assume x, and_or_distrib_right)
/- insert -/
theorem insert_def (x : α) (s : set α) : insert x s = { y | y = x ∨ y ∈ s } := rfl
@[simp] theorem insert_of_has_insert (x : α) (s : set α) : has_insert.insert x s = insert x s := rfl
@[simp] theorem subset_insert (x : α) (s : set α) : s ⊆ insert x s :=
assume y ys, or.inr ys
theorem mem_insert (x : α) (s : set α) : x ∈ insert x s :=
or.inl rfl
theorem mem_insert_of_mem {x : α} {s : set α} (y : α) : x ∈ s → x ∈ insert y s := or.inr
theorem eq_or_mem_of_mem_insert {x a : α} {s : set α} : x ∈ insert a s → x = a ∨ x ∈ s := id
theorem mem_of_mem_insert_of_ne {x a : α} {s : set α} (xin : x ∈ insert a s) : x ≠ a → x ∈ s :=
by finish [insert_def]
@[simp] theorem mem_insert_iff {x a : α} {s : set α} : x ∈ insert a s ↔ (x = a ∨ x ∈ s) := iff.rfl
@[simp] theorem insert_eq_of_mem {a : α} {s : set α} (h : a ∈ s) : insert a s = s :=
by finish [ext_iff, iff_def]
theorem insert_subset : insert a s ⊆ t ↔ (a ∈ t ∧ s ⊆ t) :=
by simp [subset_def, or_imp_distrib, forall_and_distrib]
theorem insert_subset_insert (h : s ⊆ t) : insert a s ⊆ insert a t :=
assume a', or.imp_right (@h a')
theorem ssubset_insert {s : set α} {a : α} (h : a ∉ s) : s ⊂ insert a s :=
by finish [ssubset_def, ext_iff]
theorem insert_comm (a b : α) (s : set α) : insert a (insert b s) = insert b (insert a s) :=
ext $ by simp [or.left_comm]
theorem insert_union : insert a s ∪ t = insert a (s ∪ t) :=
set.ext $ assume a, by simp [or.comm, or.left_comm]
@[simp] theorem union_insert : s ∪ insert a t = insert a (s ∪ t) :=
set.ext $ assume a, by simp [or.comm, or.left_comm]
-- TODO(Jeremy): make this automatic
theorem insert_ne_empty (a : α) (s : set α) : insert a s ≠ ∅ :=
by safe [ext_iff, iff_def]; have h' := a_1 a; finish
-- useful in proofs by induction
theorem forall_of_forall_insert {P : α → Prop} {a : α} {s : set α} (h : ∀ x, x ∈ insert a s → P x) :
∀ x, x ∈ s → P x :=
by finish
theorem forall_insert_of_forall {P : α → Prop} {a : α} {s : set α} (h : ∀ x, x ∈ s → P x) (ha : P a) :
∀ x, x ∈ insert a s → P x :=
by finish
theorem ball_insert_iff {P : α → Prop} {a : α} {s : set α} :
(∀ x ∈ insert a s, P x) ↔ P a ∧ (∀x ∈ s, P x) :=
by finish [iff_def]
/- singletons -/
theorem singleton_def (a : α) : ({a} : set α) = insert a ∅ := rfl
@[simp] theorem mem_singleton_iff {a b : α} : a ∈ ({b} : set α) ↔ a = b :=
by finish [singleton_def]
-- TODO: again, annotation needed
@[simp] theorem mem_singleton (a : α) : a ∈ ({a} : set α) := by finish
theorem eq_of_mem_singleton {x y : α} (h : x ∈ ({y} : set α)) : x = y :=
by finish
@[simp] theorem singleton_eq_singleton_iff {x y : α} : {x} = ({y} : set α) ↔ x = y :=
by finish [ext_iff, iff_def]
theorem mem_singleton_of_eq {x y : α} (H : x = y) : x ∈ ({y} : set α) :=
by finish
theorem insert_eq (x : α) (s : set α) : insert x s = ({x} : set α) ∪ s :=
by finish [ext_iff, or_comm]
@[simp] theorem pair_eq_singleton (a : α) : ({a, a} : set α) = {a} :=
by finish
@[simp] theorem singleton_ne_empty (a : α) : ({a} : set α) ≠ ∅ := insert_ne_empty _ _
@[simp] theorem singleton_subset_iff {a : α} {s : set α} : {a} ⊆ s ↔ a ∈ s :=
⟨λh, h (by simp), λh b e, by simp at e; simp [*]⟩
theorem set_compr_eq_eq_singleton {a : α} : {b | b = a} = {a} :=
set.ext $ by simp
theorem union_singleton : s ∪ {a} = insert a s :=
by simp [singleton_def]
theorem singleton_inter_eq_empty : {a} ∩ s = ∅ ↔ a ∉ s :=
by simp [eq_empty_iff_forall_not_mem]
theorem inter_singleton_eq_empty : s ∩ {a} = ∅ ↔ a ∉ s :=
by rw [inter_comm, singleton_inter_eq_empty]
/- separation -/
theorem mem_sep {s : set α} {p : α → Prop} {x : α} (xs : x ∈ s) (px : p x) : x ∈ {x ∈ s | p x} :=
⟨xs, px⟩
@[simp] theorem mem_sep_eq {s : set α} {p : α → Prop} {x : α} : x ∈ {x ∈ s | p x} = (x ∈ s ∧ p x) := rfl
theorem mem_sep_iff {s : set α} {p : α → Prop} {x : α} : x ∈ {x ∈ s | p x} ↔ x ∈ s ∧ p x :=
iff.rfl
theorem eq_sep_of_subset {s t : set α} (ssubt : s ⊆ t) : s = {x ∈ t | x ∈ s} :=
by finish [ext_iff, iff_def, subset_def]
theorem sep_subset (s : set α) (p : α → Prop) : {x ∈ s | p x} ⊆ s :=
assume x, and.left
theorem forall_not_of_sep_empty {s : set α} {p : α → Prop} (h : {x ∈ s | p x} = ∅) :
∀ x ∈ s, ¬ p x :=
by finish [ext_iff]
/- complement -/
theorem mem_compl {s : set α} {x : α} (h : x ∉ s) : x ∈ -s := h
theorem not_mem_of_mem_compl {s : set α} {x : α} (h : x ∈ -s) : x ∉ s := h
@[simp] theorem mem_compl_eq (s : set α) (x : α) : x ∈ -s = (x ∉ s) := rfl
theorem mem_compl_iff (s : set α) (x : α) : x ∈ -s ↔ x ∉ s := iff.rfl
@[simp] theorem inter_compl_self (s : set α) : s ∩ -s = ∅ :=
by finish [ext_iff]
@[simp] theorem compl_inter_self (s : set α) : -s ∩ s = ∅ :=
by finish [ext_iff]
@[simp] theorem compl_empty : -(∅ : set α) = univ :=
by finish [ext_iff]
@[simp] theorem compl_union (s t : set α) : -(s ∪ t) = -s ∩ -t :=
by finish [ext_iff]
@[simp] theorem compl_compl (s : set α) : -(-s) = s :=
by finish [ext_iff]
-- ditto
theorem compl_inter (s t : set α) : -(s ∩ t) = -s ∪ -t :=
by finish [ext_iff]
@[simp] theorem compl_univ : -(univ : set α) = ∅ :=
by finish [ext_iff]
theorem union_eq_compl_compl_inter_compl (s t : set α) : s ∪ t = -(-s ∩ -t) :=
by simp [compl_inter, compl_compl]
theorem inter_eq_compl_compl_union_compl (s t : set α) : s ∩ t = -(-s ∪ -t) :=
by simp [compl_compl]
@[simp] theorem union_compl_self (s : set α) : s ∪ -s = univ :=
by finish [ext_iff]
@[simp] theorem compl_union_self (s : set α) : -s ∪ s = univ :=
by finish [ext_iff]
theorem compl_comp_compl : compl ∘ compl = @id (set α) :=
funext compl_compl
theorem compl_subset_comm {s t : set α} : -s ⊆ t ↔ -t ⊆ s :=
by haveI := classical.prop_decidable; exact
forall_congr (λ a, not_imp_comm)
lemma compl_subset_compl {s t : set α} : -s ⊆ -t ↔ t ⊆ s :=
by rw [compl_subset_comm, compl_compl]
theorem compl_subset_iff_union {s t : set α} : -s ⊆ t ↔ s ∪ t = univ :=
iff.symm $ eq_univ_iff_forall.trans $ forall_congr $ λ a,
by haveI := classical.prop_decidable; exact or_iff_not_imp_left
theorem subset_compl_comm {s t : set α} : s ⊆ -t ↔ t ⊆ -s :=
forall_congr $ λ a, imp_not_comm
theorem subset_compl_iff_disjoint {s t : set α} : s ⊆ -t ↔ s ∩ t = ∅ :=
iff.trans (forall_congr $ λ a, and_imp.symm) subset_empty_iff
/- set difference -/
theorem diff_eq (s t : set α) : s \ t = s ∩ -t := rfl
@[simp] theorem mem_diff {s t : set α} (x : α) : x ∈ s \ t ↔ x ∈ s ∧ x ∉ t := iff.rfl
theorem mem_diff_of_mem {s t : set α} {x : α} (h1 : x ∈ s) (h2 : x ∉ t) : x ∈ s \ t :=
⟨h1, h2⟩
theorem mem_of_mem_diff {s t : set α} {x : α} (h : x ∈ s \ t) : x ∈ s :=
h.left
theorem not_mem_of_mem_diff {s t : set α} {x : α} (h : x ∈ s \ t) : x ∉ t :=
h.right
theorem union_diff_cancel {s t : set α} (h : s ⊆ t) : s ∪ (t \ s) = t :=
by finish [ext_iff, iff_def, subset_def]
theorem union_diff_cancel_left {s t : set α} (h : s ∩ t ⊆ ∅) : (s ∪ t) \ s = t :=
by finish [ext_iff, iff_def, subset_def]
theorem union_diff_cancel_right {s t : set α} (h : s ∩ t ⊆ ∅) : (s ∪ t) \ t = s :=
by finish [ext_iff, iff_def, subset_def]
theorem union_diff_left {s t : set α} : (s ∪ t) \ s = t \ s :=
by finish [ext_iff, iff_def]
theorem union_diff_right {s t : set α} : (s ∪ t) \ t = s \ t :=
by finish [ext_iff, iff_def]
theorem union_diff_distrib {s t u : set α} : (s ∪ t) \ u = s \ u ∪ t \ u :=
inter_distrib_right _ _ _
theorem inter_diff_assoc (a b c : set α) : (a ∩ b) \ c = a ∩ (b \ c) :=
inter_assoc _ _ _
theorem inter_diff_self (a b : set α) : a ∩ (b \ a) = ∅ :=
by finish [ext_iff]
theorem inter_union_diff (s t : set α) : (s ∩ t) ∪ (s \ t) = s :=
by finish [ext_iff, iff_def]
theorem diff_subset (s t : set α) : s \ t ⊆ s :=
by finish [subset_def]
theorem diff_subset_diff {s₁ s₂ t₁ t₂ : set α} : s₁ ⊆ s₂ → t₂ ⊆ t₁ → s₁ \ t₁ ⊆ s₂ \ t₂ :=
by finish [subset_def]
theorem diff_subset_diff_left {s₁ s₂ t : set α} (h : s₁ ⊆ s₂) : s₁ \ t ⊆ s₂ \ t :=
diff_subset_diff h (by refl)
theorem diff_subset_diff_right {s t u : set α} (h : t ⊆ u) : s \ u ⊆ s \ t :=
diff_subset_diff (subset.refl s) h
theorem compl_eq_univ_diff (s : set α) : -s = univ \ s :=
by finish [ext_iff]
theorem diff_eq_empty {s t : set α} : s \ t = ∅ ↔ s ⊆ t :=
⟨assume h x hx, classical.by_contradiction $ assume : x ∉ t, show x ∈ (∅ : set α), from h ▸ ⟨hx, this⟩,
assume h, eq_empty_of_subset_empty $ assume x ⟨hx, hnx⟩, hnx $ h hx⟩
@[simp] theorem diff_empty {s : set α} : s \ ∅ = s :=
set.ext $ assume x, ⟨assume ⟨hx, _⟩, hx, assume h, ⟨h, not_false⟩⟩
theorem diff_diff {u : set α} : s \ t \ u = s \ (t ∪ u) :=
set.ext $ by simp [not_or_distrib, and.comm, and.left_comm]
lemma diff_subset_iff {s t u : set α} : s \ t ⊆ u ↔ s ⊆ t ∪ u :=
⟨assume h x xs, classical.by_cases or.inl (assume nxt, or.inr (h ⟨xs, nxt⟩)),
assume h x ⟨xs, nxt⟩, or.resolve_left (h xs) nxt⟩
lemma diff_subset_comm {s t u : set α} : s \ t ⊆ u ↔ s \ u ⊆ t :=
by rw [diff_subset_iff, diff_subset_iff, union_comm]
@[simp] theorem insert_diff (h : a ∈ t) : insert a s \ t = s \ t :=
set.ext $ by intro; constructor; simp [or_imp_distrib, h] {contextual := tt}
theorem union_diff_self {s t : set α} : s ∪ (t \ s) = s ∪ t :=
by finish [ext_iff, iff_def]
theorem diff_union_self {s t : set α} : (s \ t) ∪ t = s ∪ t :=
by rw [union_comm, union_diff_self, union_comm]
theorem diff_inter_self {a b : set α} : (b \ a) ∩ a = ∅ :=
set.ext $ by simp [iff_def] {contextual:=tt}
theorem diff_eq_self {s t : set α} : s \ t = s ↔ t ∩ s ⊆ ∅ :=
by finish [ext_iff, iff_def, subset_def]
@[simp] theorem diff_singleton_eq_self {a : α} {s : set α} (h : a ∉ s) : s \ {a} = s :=
diff_eq_self.2 $ by simp [singleton_inter_eq_empty.2 h]
@[simp] theorem insert_diff_singleton {a : α} {s : set α} :
insert a (s \ {a}) = insert a s :=
by simp [insert_eq, union_diff_self]
/- powerset -/
theorem mem_powerset {x s : set α} (h : x ⊆ s) : x ∈ powerset s := h
theorem subset_of_mem_powerset {x s : set α} (h : x ∈ powerset s) : x ⊆ s := h
theorem mem_powerset_iff (x s : set α) : x ∈ powerset s ↔ x ⊆ s := iff.rfl
/- inverse image -/
/-- The preimage of `s : set β` by `f : α → β`, written `f ⁻¹' s`,
is the set of `x : α` such that `f x ∈ s`. -/
def preimage {α : Type u} {β : Type v} (f : α → β) (s : set β) : set α := {x | f x ∈ s}
infix ` ⁻¹' `:80 := preimage
section preimage
variables {f : α → β} {g : β → γ}
@[simp] theorem preimage_empty : f ⁻¹' ∅ = ∅ := rfl
@[simp] theorem mem_preimage_eq {s : set β} {a : α} : (a ∈ f ⁻¹' s) = (f a ∈ s) := rfl
theorem preimage_mono {s t : set β} (h : s ⊆ t) : f ⁻¹' s ⊆ f ⁻¹' t :=
assume x hx, h hx
@[simp] theorem preimage_univ : f ⁻¹' univ = univ := rfl
@[simp] theorem preimage_inter {s t : set β} : f ⁻¹' (s ∩ t) = f ⁻¹' s ∩ f ⁻¹' t := rfl
@[simp] theorem preimage_union {s t : set β} : f ⁻¹' (s ∪ t) = f ⁻¹' s ∪ f ⁻¹' t := rfl
@[simp] theorem preimage_compl {s : set β} : f ⁻¹' (- s) = - (f ⁻¹' s) := rfl
@[simp] theorem preimage_diff (f : α → β) (s t : set β) :
f ⁻¹' (s \ t) = f ⁻¹' s \ f ⁻¹' t := rfl
@[simp] theorem preimage_set_of_eq {p : α → Prop} {f : β → α} : f ⁻¹' {a | p a} = {a | p (f a)} :=
rfl
theorem preimage_id {s : set α} : id ⁻¹' s = s := rfl
theorem preimage_comp {s : set γ} : (g ∘ f) ⁻¹' s = f ⁻¹' (g ⁻¹' s) := rfl
theorem eq_preimage_subtype_val_iff {p : α → Prop} {s : set (subtype p)} {t : set α} :
s = subtype.val ⁻¹' t ↔ (∀x (h : p x), (⟨x, h⟩ : subtype p) ∈ s ↔ x ∈ t) :=
⟨assume s_eq x h, by rw [s_eq]; simp,
assume h, set.ext $ assume ⟨x, hx⟩, by simp [h]⟩
end preimage
/- function image -/
section image
infix ` '' `:80 := image
/-- Two functions `f₁ f₂ : α → β` are equal on `s`
if `f₁ x = f₂ x` for all `x ∈ a`. -/
@[reducible] def eq_on (f1 f2 : α → β) (a : set α) : Prop :=
∀ x ∈ a, f1 x = f2 x
-- TODO(Jeremy): use bounded exists in image
theorem mem_image_iff_bex {f : α → β} {s : set α} {y : β} :
y ∈ f '' s ↔ ∃ x (_ : x ∈ s), f x = y := bex_def.symm
theorem mem_image_eq (f : α → β) (s : set α) (y: β) : y ∈ f '' s = ∃ x, x ∈ s ∧ f x = y := rfl
@[simp] theorem mem_image (f : α → β) (s : set α) (y : β) : y ∈ f '' s ↔ ∃ x, x ∈ s ∧ f x = y := iff.rfl
theorem mem_image_of_mem (f : α → β) {x : α} {a : set α} (h : x ∈ a) : f x ∈ f '' a :=
⟨_, h, rfl⟩
theorem mem_image_of_injective {f : α → β} {a : α} {s : set α} (hf : injective f) :
f a ∈ f '' s ↔ a ∈ s :=
iff.intro
(assume ⟨b, hb, eq⟩, (hf eq) ▸ hb)
(assume h, mem_image_of_mem _ h)
theorem ball_image_of_ball {f : α → β} {s : set α} {p : β → Prop}
(h : ∀ x ∈ s, p (f x)) : ∀ y ∈ f '' s, p y :=
by finish [mem_image_eq]
@[simp] theorem ball_image_iff {f : α → β} {s : set α} {p : β → Prop} :
(∀ y ∈ f '' s, p y) ↔ (∀ x ∈ s, p (f x)) :=
iff.intro
(assume h a ha, h _ $ mem_image_of_mem _ ha)
(assume h b ⟨a, ha, eq⟩, eq ▸ h a ha)
theorem mono_image {f : α → β} {s t : set α} (h : s ⊆ t) : f '' s ⊆ f '' t :=
assume x ⟨y, hy, y_eq⟩, y_eq ▸ mem_image_of_mem _ $ h hy
theorem mem_image_elim {f : α → β} {s : set α} {C : β → Prop} (h : ∀ (x : α), x ∈ s → C (f x)) :
∀{y : β}, y ∈ f '' s → C y
| ._ ⟨a, a_in, rfl⟩ := h a a_in
theorem mem_image_elim_on {f : α → β} {s : set α} {C : β → Prop} {y : β} (h_y : y ∈ f '' s)
(h : ∀ (x : α), x ∈ s → C (f x)) : C y :=
mem_image_elim h h_y
@[congr] lemma image_congr {f g : α → β} {s : set α}
(h : ∀a∈s, f a = g a) : f '' s = g '' s :=
by safe [ext_iff, iff_def]
theorem image_eq_image_of_eq_on {f₁ f₂ : α → β} {s : set α} (heq : eq_on f₁ f₂ s) :
f₁ '' s = f₂ '' s :=
image_congr heq
theorem image_comp (f : β → γ) (g : α → β) (a : set α) : (f ∘ g) '' a = f '' (g '' a) :=
subset.antisymm
(ball_image_of_ball $ assume a ha, mem_image_of_mem _ $ mem_image_of_mem _ ha)
(ball_image_of_ball $ ball_image_of_ball $ assume a ha, mem_image_of_mem _ ha)
/- Proof is removed as it uses generated names
TODO(Jeremy): make automatic,
begin
safe [ext_iff, iff_def, mem_image, (∘)],
have h' := h_2 (g a_2),
finish
end -/
theorem image_subset {a b : set α} (f : α → β) (h : a ⊆ b) : f '' a ⊆ f '' b :=
by finish [subset_def, mem_image_eq]
theorem image_union (f : α → β) (s t : set α) :
f '' (s ∪ t) = f '' s ∪ f '' t :=
by finish [ext_iff, iff_def, mem_image_eq]
@[simp] theorem image_empty (f : α → β) : f '' ∅ = ∅ := ext $ by simp
theorem image_inter_on {f : α → β} {s t : set α} (h : ∀x∈t, ∀y∈s, f x = f y → x = y) :
f '' s ∩ f '' t = f '' (s ∩ t) :=
subset.antisymm
(assume b ⟨⟨a₁, ha₁, h₁⟩, ⟨a₂, ha₂, h₂⟩⟩,
have a₂ = a₁, from h _ ha₂ _ ha₁ (by simp *),
⟨a₁, ⟨ha₁, this ▸ ha₂⟩, h₁⟩)
(subset_inter (mono_image $ inter_subset_left _ _) (mono_image $ inter_subset_right _ _))
theorem image_inter {f : α → β} {s t : set α} (H : injective f) :
f '' s ∩ f '' t = f '' (s ∩ t) :=
image_inter_on (assume x _ y _ h, H h)
theorem image_univ_of_surjective {ι : Type*} {f : ι → β} (H : surjective f) : f '' univ = univ :=
eq_univ_of_forall $ by simp [image]; exact H
@[simp] theorem image_singleton {f : α → β} {a : α} : f '' {a} = {f a} :=
set.ext $ λ x, by simp [image]; rw eq_comm
theorem fix_set_compl (t : set α) : compl t = - t := rfl
-- TODO(Jeremy): there is an issue with - t unfolding to compl t
theorem mem_compl_image (t : set α) (S : set (set α)) :
t ∈ compl '' S ↔ -t ∈ S :=
begin
suffices : ∀ x, -x = t ↔ -t = x, {simp [fix_set_compl, this]},
intro x, split; { intro e, subst e, simp }
end
@[simp] theorem image_id (s : set α) : id '' s = s := ext $ by simp
theorem compl_compl_image (S : set (set α)) :
compl '' (compl '' S) = S :=
by rw [← image_comp, compl_comp_compl, image_id]
theorem image_insert_eq {f : α → β} {a : α} {s : set α} :
f '' (insert a s) = insert (f a) (f '' s) :=
ext $ by simp [and_or_distrib_left, exists_or_distrib, eq_comm, or_comm, and_comm]
theorem image_subset_preimage_of_inverse {f : α → β} {g : β → α}
(I : left_inverse g f) (s : set α) : f '' s ⊆ g ⁻¹' s :=
λ b ⟨a, h, e⟩, e ▸ ((I a).symm ▸ h : g (f a) ∈ s)
theorem preimage_subset_image_of_inverse {f : α → β} {g : β → α}
(I : left_inverse g f) (s : set β) : f ⁻¹' s ⊆ g '' s :=
λ b h, ⟨f b, h, I b⟩
theorem image_eq_preimage_of_inverse {f : α → β} {g : β → α}
(h₁ : left_inverse g f) (h₂ : right_inverse g f) :
image f = preimage g :=
funext $ λ s, subset.antisymm
(image_subset_preimage_of_inverse h₁ s)
(preimage_subset_image_of_inverse h₂ s)
theorem mem_image_iff_of_inverse {f : α → β} {g : β → α} {b : β} {s : set α}
(h₁ : left_inverse g f) (h₂ : right_inverse g f) :
b ∈ f '' s ↔ g b ∈ s :=
by rw image_eq_preimage_of_inverse h₁ h₂; refl
theorem image_compl_subset {f : α → β} {s : set α} (H : injective f) : f '' -s ⊆ -(f '' s) :=
subset_compl_iff_disjoint.2 $ by simp [image_inter H]
theorem subset_image_compl {f : α → β} {s : set α} (H : surjective f) : -(f '' s) ⊆ f '' -s :=
compl_subset_iff_union.2 $
by rw ← image_union; simp [image_univ_of_surjective H]
theorem image_compl_eq {f : α → β} {s : set α} (H : bijective f) : f '' -s = -(f '' s) :=
subset.antisymm (image_compl_subset H.1) (subset_image_compl H.2)
/- image and preimage are a Galois connection -/
theorem image_subset_iff {s : set α} {t : set β} {f : α → β} :
f '' s ⊆ t ↔ s ⊆ f ⁻¹' t :=
ball_image_iff
theorem image_preimage_subset (f : α → β) (s : set β) :
f '' (f ⁻¹' s) ⊆ s :=
image_subset_iff.2 (subset.refl _)
theorem subset_preimage_image (f : α → β) (s : set α) :
s ⊆ f ⁻¹' (f '' s) :=
λ x, mem_image_of_mem f
theorem preimage_image_eq {f : α → β} (s : set α) (h : injective f) : f ⁻¹' (f '' s) = s :=
subset.antisymm
(λ x ⟨y, hy, e⟩, h e ▸ hy)
(subset_preimage_image f s)
theorem image_preimage_eq {f : α → β} {s : set β} (h : surjective f) : f '' (f ⁻¹' s) = s :=
subset.antisymm
(image_preimage_subset f s)
(λ x hx, let ⟨y, e⟩ := h x in ⟨y, (e.symm ▸ hx : f y ∈ s), e⟩)
theorem compl_image : image (@compl α) = preimage compl :=
image_eq_preimage_of_inverse compl_compl compl_compl
theorem compl_image_set_of {α : Type u} {p : set α → Prop} :
compl '' {x | p x} = {x | p (- x)} :=
congr_fun compl_image p
theorem inter_preimage_subset (s : set α) (t : set β) (f : α → β) :
s ∩ f ⁻¹' t ⊆ f ⁻¹' (f '' s ∩ t) :=
λ x h, ⟨mem_image_of_mem _ h.left, h.right⟩
theorem union_preimage_subset (s : set α) (t : set β) (f : α → β) :
s ∪ f ⁻¹' t ⊆ f ⁻¹' (f '' s ∪ t) :=
λ x h, or.elim h (λ l, or.inl $ mem_image_of_mem _ l) (λ r, or.inr r)
theorem subset_image_union (f : α → β) (s : set α) (t : set β) :
f '' (s ∪ f ⁻¹' t) ⊆ f '' s ∪ t :=
image_subset_iff.2 (union_preimage_subset _ _ _)
lemma subtype_val_image {p : α → Prop} {s : set (subtype p)} :
subtype.val '' s = {x | ∃h : p x, (⟨x, h⟩ : subtype p) ∈ s} :=
set.ext $ assume a,
⟨assume ⟨⟨a', ha'⟩, in_s, h_eq⟩, h_eq ▸ ⟨ha', in_s⟩,
assume ⟨ha, in_s⟩, ⟨⟨a, ha⟩, in_s, rfl⟩⟩
end image
theorem univ_eq_true_false : univ = ({true, false} : set Prop) :=
eq.symm $ eq_univ_of_forall $ classical.cases (by simp) (by simp)
section range
variables {f : ι → α}
open function
/-- Range of a function.
This function is more flexible than `f '' univ`, as the image requires that the domain is in Type
and not an arbitrary Sort. -/
def range (f : ι → α) : set α := {x | ∃y, f y = x}
@[simp] theorem mem_range {x : α} : x ∈ range f ↔ ∃ y, f y = x := iff.rfl
theorem mem_range_self (i : ι) : f i ∈ range f := ⟨i, rfl⟩
theorem forall_range_iff {p : α → Prop} : (∀ a ∈ range f, p a) ↔ (∀ i, p (f i)) :=
⟨assume h i, h (f i) (mem_range_self _), assume h a ⟨i, (hi : f i = a)⟩, hi ▸ h i⟩
theorem range_iff_surjective : range f = univ ↔ surjective f :=
eq_univ_iff_forall
@[simp] theorem range_id : range (@id α) = univ := range_iff_surjective.2 surjective_id
@[simp] theorem image_univ {ι : Type*} {f : ι → β} : f '' univ = range f :=
set.ext $ by simp [image, range]
theorem range_comp {g : α → β} : range (g ∘ f) = g '' range f :=
subset.antisymm
(forall_range_iff.mpr $ assume i, mem_image_of_mem g (mem_range_self _))
(ball_image_iff.mpr $ forall_range_iff.mpr mem_range_self)
theorem range_subset_iff {ι : Type*} {f : ι → β} {s : set β} : range f ⊆ s ↔ ∀ y, f y ∈ s :=
forall_range_iff
theorem image_preimage_eq_inter_range {f : α → β} {t : set β} :
f '' preimage f t = t ∩ range f :=
set.ext $ assume x, ⟨assume ⟨x, hx, heq⟩, heq ▸ ⟨hx, mem_range_self _⟩,
assume ⟨hx, ⟨y, h_eq⟩⟩, h_eq ▸ mem_image_of_mem f $
show y ∈ preimage f t, by simp [preimage, h_eq, hx]⟩
@[simp] theorem quot_mk_range_eq [setoid α] : range (λx : α, ⟦x⟧) = univ :=
range_iff_surjective.2 quot.exists_rep
end range
lemma subtype_val_range {p : α → Prop} :
range (@subtype.val _ p) = {x | p x} :=
by rw ← image_univ; simp [-image_univ, subtype_val_image]
/-- The set `s` is pairwise `r` if `r x y` for all *distinct* `x y ∈ s`. -/
def pairwise_on (s : set α) (r : α → α → Prop) := ∀ x ∈ s, ∀ y ∈ s, x ≠ y → r x y
end set
namespace set
section prod
variables {α : Type*} {β : Type*} {γ : Type*} {δ : Type*}
variables {s s₁ s₂ : set α} {t t₁ t₂ : set β}
/-- The cartesian product `prod s t` is the set of `(a, b)`
such that `a ∈ s` and `b ∈ t`. -/
protected def prod (s : set α) (t : set β) : set (α × β) :=
{p | p.1 ∈ s ∧ p.2 ∈ t}
theorem mem_prod_eq {p : α × β} : p ∈ set.prod s t = (p.1 ∈ s ∧ p.2 ∈ t) := rfl
@[simp] theorem mem_prod {p : α × β} : p ∈ set.prod s t ↔ p.1 ∈ s ∧ p.2 ∈ t := iff.rfl
@[simp] theorem prod_empty {s : set α} : set.prod s ∅ = (∅ : set (α × β)) :=
set.ext $ by simp [set.prod]
@[simp] theorem empty_prod {t : set β} : set.prod ∅ t = (∅ : set (α × β)) :=
set.ext $ by simp [set.prod]
theorem insert_prod {a : α} {s : set α} {t : set β} :
set.prod (insert a s) t = (prod.mk a '' t) ∪ set.prod s t :=
set.ext begin simp [set.prod, image, iff_def, or_imp_distrib] {contextual := tt}; cc end
theorem prod_insert {b : β} {s : set α} {t : set β} :
set.prod s (insert b t) = ((λa, (a, b)) '' s) ∪ set.prod s t :=
set.ext begin simp [set.prod, image, iff_def, or_imp_distrib] {contextual := tt}; cc end
theorem prod_preimage_eq {f : γ → α} {g : δ → β} :
set.prod (preimage f s) (preimage g t) = preimage (λp, (f p.1, g p.2)) (set.prod s t) := rfl
theorem prod_mono {s₁ s₂ : set α} {t₁ t₂ : set β} (hs : s₁ ⊆ s₂) (ht : t₁ ⊆ t₂) :
set.prod s₁ t₁ ⊆ set.prod s₂ t₂ :=
assume x ⟨h₁, h₂⟩, ⟨hs h₁, ht h₂⟩
theorem prod_inter_prod : set.prod s₁ t₁ ∩ set.prod s₂ t₂ = set.prod (s₁ ∩ s₂) (t₁ ∩ t₂) :=
subset.antisymm
(assume ⟨a, b⟩ ⟨⟨ha₁, hb₁⟩, ⟨ha₂, hb₂⟩⟩, ⟨⟨ha₁, ha₂⟩, ⟨hb₁, hb₂⟩⟩)
(subset_inter
(prod_mono (inter_subset_left _ _) (inter_subset_left _ _))
(prod_mono (inter_subset_right _ _) (inter_subset_right _ _)))
theorem image_swap_prod : (λp:β×α, (p.2, p.1)) '' set.prod t s = set.prod s t :=
set.ext $ assume ⟨a, b⟩, by simp [mem_image_eq, set.prod, and_comm]; exact
⟨ assume ⟨b', a', ⟨h_a, h_b⟩, h⟩, by subst a'; subst b'; assumption,
assume h, ⟨b, a, ⟨rfl, rfl⟩, h⟩⟩
theorem image_swap_eq_preimage_swap : image (@prod.swap α β) = preimage prod.swap :=
image_eq_preimage_of_inverse prod.swap_left_inverse prod.swap_right_inverse
theorem prod_image_image_eq {m₁ : α → γ} {m₂ : β → δ} :
set.prod (image m₁ s) (image m₂ t) = image (λp:α×β, (m₁ p.1, m₂ p.2)) (set.prod s t) :=
set.ext $ by simp [-exists_and_distrib_right, exists_and_distrib_right.symm, and.left_comm, and.assoc, and.comm]
theorem prod_range_range_eq {α β γ δ} {m₁ : α → γ} {m₂ : β → δ} :
set.prod (range m₁) (range m₂) = range (λp:α×β, (m₁ p.1, m₂ p.2)) :=
set.ext $ by simp [range]
@[simp] theorem prod_singleton_singleton {a : α} {b : β} :
set.prod {a} {b} = ({(a, b)} : set (α×β)) :=
set.ext $ by simp [set.prod]
theorem prod_neq_empty_iff {s : set α} {t : set β} :
set.prod s t ≠ ∅ ↔ (s ≠ ∅ ∧ t ≠ ∅) :=
by simp [not_eq_empty_iff_exists]
@[simp] theorem prod_mk_mem_set_prod_eq {a : α} {b : β} {s : set α} {t : set β} :
(a, b) ∈ set.prod s t = (a ∈ s ∧ b ∈ t) := rfl
@[simp] theorem univ_prod_univ : set.prod univ univ = (univ : set (α×β)) :=
set.ext $ assume ⟨a, b⟩, by simp
end prod
end set
|
c82e64e8079c99632a30d8d9b4e091974871dc9b | 22e97a5d648fc451e25a06c668dc03ac7ed7bc25 | /src/data/zsqrtd/gaussian_int.lean | c09fc8fa3f0fb0a8eec94212421b64e9810ea752 | [
"Apache-2.0"
] | permissive | keeferrowan/mathlib | f2818da875dbc7780830d09bd4c526b0764a4e50 | aad2dfc40e8e6a7e258287a7c1580318e865817e | refs/heads/master | 1,661,736,426,952 | 1,590,438,032,000 | 1,590,438,032,000 | 266,892,663 | 0 | 0 | Apache-2.0 | 1,590,445,835,000 | 1,590,445,835,000 | null | UTF-8 | Lean | false | false | 12,634 | lean | /-
Copyright (c) 2019 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Chris Hughes
-/
import data.zsqrtd.basic
import data.complex.basic
import ring_theory.principal_ideal_domain
import number_theory.quadratic_reciprocity
/-!
# Gaussian integers
The Gaussian integers are complex integer, complex numbers whose real and imaginary parts are both
integers.
## Main definitions
The Euclidean domain structure on `ℤ[i]` is defined in this file.
The homomorphism `to_complex` into the complex numbers is also defined in this file.
## Main statements
`prime_iff_mod_four_eq_three_of_nat_prime`
A prime natural number is prime in `ℤ[i]` if and only if it is `3` mod `4`
## Notations
This file uses the local notation `ℤ[i]` for `gaussian_int`
## Implementation notes
Gaussian integers are implemented using the more general definition `zsqrtd`, the type of integers
adjoined a square root of `d`, in this case `-1`. The definition is reducible, so that properties
and definitions about `zsqrtd` can easily be used.
-/
open zsqrtd complex
@[reducible] def gaussian_int : Type := zsqrtd (-1)
local notation `ℤ[i]` := gaussian_int
namespace gaussian_int
instance : has_repr ℤ[i] := ⟨λ x, "⟨" ++ repr x.re ++ ", " ++ repr x.im ++ "⟩"⟩
instance : comm_ring ℤ[i] := zsqrtd.comm_ring
def to_complex (x : ℤ[i]) : ℂ := x.re + x.im * I
instance : has_coe (ℤ[i]) ℂ := ⟨to_complex⟩
lemma to_complex_def (x : ℤ[i]) : (x : ℂ) = x.re + x.im * I := rfl
lemma to_complex_def' (x y : ℤ) : ((⟨x, y⟩ : ℤ[i]) : ℂ) = x + y * I := by simp [to_complex_def]
lemma to_complex_def₂ (x : ℤ[i]) : (x : ℂ) = ⟨x.re, x.im⟩ :=
by apply complex.ext; simp [to_complex_def]
instance to_complex.is_ring_hom : is_ring_hom to_complex :=
by refine_struct {..}; intros; apply complex.ext; simp [sub_eq_add_neg, to_complex]
instance : is_ring_hom (coe : ℤ[i] → ℂ) := to_complex.is_ring_hom
@[simp] lemma to_real_re (x : ℤ[i]) : ((x.re : ℤ) : ℝ) = (x : ℂ).re := by simp [to_complex_def]
@[simp] lemma to_real_im (x : ℤ[i]) : ((x.im : ℤ) : ℝ) = (x : ℂ).im := by simp [to_complex_def]
@[simp] lemma to_complex_re (x y : ℤ) : ((⟨x, y⟩ : ℤ[i]) : ℂ).re = x := by simp [to_complex_def]
@[simp] lemma to_complex_im (x y : ℤ) : ((⟨x, y⟩ : ℤ[i]) : ℂ).im = y := by simp [to_complex_def]
@[simp] lemma to_complex_add (x y : ℤ[i]) : ((x + y : ℤ[i]) : ℂ) = x + y := is_ring_hom.map_add coe
@[simp] lemma to_complex_mul (x y : ℤ[i]) : ((x * y : ℤ[i]) : ℂ) = x * y := is_ring_hom.map_mul coe
@[simp] lemma to_complex_one : ((1 : ℤ[i]) : ℂ) = 1 := is_ring_hom.map_one coe
@[simp] lemma to_complex_zero : ((0 : ℤ[i]) : ℂ) = 0 := is_ring_hom.map_zero coe
@[simp] lemma to_complex_neg (x : ℤ[i]) : ((-x : ℤ[i]) : ℂ) = -x := is_ring_hom.map_neg coe
@[simp] lemma to_complex_sub (x y : ℤ[i]) : ((x - y : ℤ[i]) : ℂ) = x - y := is_ring_hom.map_sub coe
@[simp] lemma to_complex_inj {x y : ℤ[i]} : (x : ℂ) = y ↔ x = y :=
by cases x; cases y; simp [to_complex_def₂]
@[simp] lemma to_complex_eq_zero {x : ℤ[i]} : (x : ℂ) = 0 ↔ x = 0 :=
by rw [← to_complex_zero, to_complex_inj]
@[simp] lemma nat_cast_real_norm (x : ℤ[i]) : (x.norm : ℝ) = (x : ℂ).norm_sq :=
by rw [norm, norm_sq]; simp
@[simp] lemma nat_cast_complex_norm (x : ℤ[i]) : (x.norm : ℂ) = (x : ℂ).norm_sq :=
by cases x; rw [norm, norm_sq]; simp
lemma norm_nonneg (x : ℤ[i]) : 0 ≤ norm x := norm_nonneg trivial _
@[simp] lemma norm_eq_zero {x : ℤ[i]} : norm x = 0 ↔ x = 0 :=
by rw [← @int.cast_inj ℝ _ _ _]; simp
lemma norm_pos {x : ℤ[i]} : 0 < norm x ↔ x ≠ 0 :=
by rw [lt_iff_le_and_ne, ne.def, eq_comm, norm_eq_zero]; simp [norm_nonneg]
@[simp] lemma coe_nat_abs_norm (x : ℤ[i]) : (x.norm.nat_abs : ℤ) = x.norm :=
int.nat_abs_of_nonneg (norm_nonneg _)
@[simp] lemma nat_cast_nat_abs_norm {α : Type*} [ring α]
(x : ℤ[i]) : (x.norm.nat_abs : α) = x.norm :=
by rw [← int.cast_coe_nat, coe_nat_abs_norm]
lemma nat_abs_norm_eq (x : ℤ[i]) : x.norm.nat_abs =
x.re.nat_abs * x.re.nat_abs + x.im.nat_abs * x.im.nat_abs :=
int.coe_nat_inj $ begin simp, simp [norm] end
protected def div (x y : ℤ[i]) : ℤ[i] :=
let n := (rat.of_int (norm y))⁻¹ in let c := y.conj in
⟨round (rat.of_int (x * c).re * n : ℚ),
round (rat.of_int (x * c).im * n : ℚ)⟩
instance : has_div ℤ[i] := ⟨gaussian_int.div⟩
lemma div_def (x y : ℤ[i]) : x / y = ⟨round ((x * conj y).re / norm y : ℚ),
round ((x * conj y).im / norm y : ℚ)⟩ :=
show zsqrtd.mk _ _ = _, by simp [rat.of_int_eq_mk, rat.mk_eq_div, div_eq_mul_inv]
lemma to_complex_div_re (x y : ℤ[i]) : ((x / y : ℤ[i]) : ℂ).re = round ((x / y : ℂ).re) :=
by rw [div_def, ← @rat.cast_round ℝ _ _];
simp [-rat.cast_round, mul_assoc, div_eq_mul_inv, mul_add, add_mul]
lemma to_complex_div_im (x y : ℤ[i]) : ((x / y : ℤ[i]) : ℂ).im = round ((x / y : ℂ).im) :=
by rw [div_def, ← @rat.cast_round ℝ _ _, ← @rat.cast_round ℝ _ _];
simp [-rat.cast_round, mul_assoc, div_eq_mul_inv, mul_add, add_mul]
local notation `abs'` := _root_.abs
lemma norm_sq_le_norm_sq_of_re_le_of_im_le {x y : ℂ} (hre : abs' x.re ≤ abs' y.re)
(him : abs' x.im ≤ abs' y.im) : x.norm_sq ≤ y.norm_sq :=
by rw [norm_sq, norm_sq, ← _root_.abs_mul_self, _root_.abs_mul,
← _root_.abs_mul_self y.re, _root_.abs_mul y.re,
← _root_.abs_mul_self x.im, _root_.abs_mul x.im,
← _root_.abs_mul_self y.im, _root_.abs_mul y.im]; exact
(add_le_add (mul_self_le_mul_self (abs_nonneg _) hre)
(mul_self_le_mul_self (abs_nonneg _) him))
lemma norm_sq_div_sub_div_lt_one (x y : ℤ[i]) :
((x / y : ℂ) - ((x / y : ℤ[i]) : ℂ)).norm_sq < 1 :=
calc ((x / y : ℂ) - ((x / y : ℤ[i]) : ℂ)).norm_sq =
((x / y : ℂ).re - ((x / y : ℤ[i]) : ℂ).re +
((x / y : ℂ).im - ((x / y : ℤ[i]) : ℂ).im) * I : ℂ).norm_sq :
congr_arg _ $ by apply complex.ext; simp
... ≤ (1 / 2 + 1 / 2 * I).norm_sq :
have abs' (2 / (2 * 2) : ℝ) = 1 / 2, by rw _root_.abs_of_nonneg; norm_num,
norm_sq_le_norm_sq_of_re_le_of_im_le
(by rw [to_complex_div_re]; simp [norm_sq, this];
simpa using abs_sub_round (x / y : ℂ).re)
(by rw [to_complex_div_im]; simp [norm_sq, this];
simpa using abs_sub_round (x / y : ℂ).im)
... < 1 : by simp [norm_sq]; norm_num
protected def mod (x y : ℤ[i]) : ℤ[i] := x - y * (x / y)
instance : has_mod ℤ[i] := ⟨gaussian_int.mod⟩
lemma mod_def (x y : ℤ[i]) : x % y = x - y * (x / y) := rfl
lemma norm_mod_lt (x : ℤ[i]) {y : ℤ[i]} (hy : y ≠ 0) : (x % y).norm < y.norm :=
have (y : ℂ) ≠ 0, by rwa [ne.def, ← to_complex_zero, to_complex_inj],
(@int.cast_lt ℝ _ _ _).1 $
calc ↑(norm (x % y)) = (x - y * (x / y : ℤ[i]) : ℂ).norm_sq : by simp [mod_def]
... = (y : ℂ).norm_sq * (((x / y) - (x / y : ℤ[i])) : ℂ).norm_sq :
by rw [← norm_sq_mul, mul_sub, mul_div_cancel' _ this]
... < (y : ℂ).norm_sq * 1 : mul_lt_mul_of_pos_left (norm_sq_div_sub_div_lt_one _ _)
(norm_sq_pos.2 this)
... = norm y : by simp
lemma nat_abs_norm_mod_lt (x : ℤ[i]) {y : ℤ[i]} (hy : y ≠ 0) :
(x % y).norm.nat_abs < y.norm.nat_abs :=
int.coe_nat_lt.1 (by simp [-int.coe_nat_lt, norm_mod_lt x hy])
lemma norm_le_norm_mul_left (x : ℤ[i]) {y : ℤ[i]} (hy : y ≠ 0) :
(norm x).nat_abs ≤ (norm (x * y)).nat_abs :=
by rw [norm_mul, int.nat_abs_mul];
exact le_mul_of_one_le_right' (nat.zero_le _)
(int.coe_nat_le.1 (by rw [coe_nat_abs_norm]; exact norm_pos.2 hy))
instance : nonzero_comm_ring ℤ[i] :=
{ zero_ne_one := dec_trivial, ..gaussian_int.comm_ring }
instance : euclidean_domain ℤ[i] :=
{ quotient := (/),
remainder := (%),
quotient_zero := λ _, by simp [div_def]; refl,
quotient_mul_add_remainder_eq := λ _ _, by simp [mod_def],
r := _,
r_well_founded := measure_wf (int.nat_abs ∘ norm),
remainder_lt := nat_abs_norm_mod_lt,
mul_left_not_lt := λ a b hb0, not_lt_of_ge $ norm_le_norm_mul_left a hb0 }
open principal_ideal_domain
lemma mod_four_eq_three_of_nat_prime_of_prime (p : ℕ) [hp : fact p.prime] (hpi : prime (p : ℤ[i])) :
p % 4 = 3 :=
hp.eq_two_or_odd.elim
(λ hp2, absurd hpi (mt irreducible_iff_prime.2 $
λ ⟨hu, h⟩, begin
have := h ⟨1, 1⟩ ⟨1, -1⟩ (hp2.symm ▸ rfl),
rw [← norm_eq_one_iff, ← norm_eq_one_iff] at this,
exact absurd this dec_trivial
end))
(λ hp1, by_contradiction $ λ hp3 : p % 4 ≠ 3,
have hp41 : p % 4 = 1,
begin
rw [← nat.mod_mul_left_mod p 2 2, show 2 * 2 = 4, from rfl] at hp1,
have := nat.mod_lt p (show 0 < 4, from dec_trivial),
revert this hp3 hp1,
generalize hm : p % 4 = m, clear hm, revert m,
exact dec_trivial,
end,
let ⟨k, hk⟩ := (zmod.exists_pow_two_eq_neg_one_iff_mod_four_ne_three p).2 $
by rw hp41; exact dec_trivial in
begin
obtain ⟨k, k_lt_p, rfl⟩ : ∃ (k' : ℕ) (h : k' < p), (k' : zmod p) = k,
{ refine ⟨k.val, k.val_lt, zmod.cast_val k⟩ },
have hpk : p ∣ k ^ 2 + 1,
by rw [← char_p.cast_eq_zero_iff (zmod p) p]; simp *,
have hkmul : (k ^ 2 + 1 : ℤ[i]) = ⟨k, 1⟩ * ⟨k, -1⟩ :=
by simp [_root_.pow_two, zsqrtd.ext],
have hpne1 : p ≠ 1, from (ne_of_lt (hp.one_lt)).symm,
have hkltp : 1 + k * k < p * p,
from calc 1 + k * k ≤ k + k * k :
add_le_add_right (nat.pos_of_ne_zero
(λ hk0, by clear_aux_decl; simp [*, nat.pow_succ] at *)) _
... = k * (k + 1) : by simp [add_comm, mul_add]
... < p * p : mul_lt_mul k_lt_p k_lt_p (nat.succ_pos _) (nat.zero_le _),
have hpk₁ : ¬ (p : ℤ[i]) ∣ ⟨k, -1⟩ :=
λ ⟨x, hx⟩, lt_irrefl (p * x : ℤ[i]).norm.nat_abs $
calc (norm (p * x : ℤ[i])).nat_abs = (norm ⟨k, -1⟩).nat_abs : by rw hx
... < (norm (p : ℤ[i])).nat_abs : by simpa [add_comm, norm] using hkltp
... ≤ (norm (p * x : ℤ[i])).nat_abs : norm_le_norm_mul_left _
(λ hx0, (show (-1 : ℤ) ≠ 0, from dec_trivial) $
by simpa [hx0] using congr_arg zsqrtd.im hx),
have hpk₂ : ¬ (p : ℤ[i]) ∣ ⟨k, 1⟩ :=
λ ⟨x, hx⟩, lt_irrefl (p * x : ℤ[i]).norm.nat_abs $
calc (norm (p * x : ℤ[i])).nat_abs = (norm ⟨k, 1⟩).nat_abs : by rw hx
... < (norm (p : ℤ[i])).nat_abs : by simpa [add_comm, norm] using hkltp
... ≤ (norm (p * x : ℤ[i])).nat_abs : norm_le_norm_mul_left _
(λ hx0, (show (1 : ℤ) ≠ 0, from dec_trivial) $
by simpa [hx0] using congr_arg zsqrtd.im hx),
have hpu : ¬ is_unit (p : ℤ[i]), from mt norm_eq_one_iff.2
(by rw [norm_nat_cast, int.nat_abs_mul, nat.mul_eq_one_iff];
exact λ h, (ne_of_lt hp.one_lt).symm h.1),
obtain ⟨y, hy⟩ := hpk,
have := hpi.2.2 ⟨k, 1⟩ ⟨k, -1⟩ ⟨y, by rw [← hkmul, ← nat.cast_mul p, ← hy]; simp⟩,
clear_aux_decl, tauto
end)
lemma sum_two_squares_of_nat_prime_of_not_irreducible (p : ℕ) [hp : fact p.prime]
(hpi : ¬irreducible (p : ℤ[i])) : ∃ a b, a^2 + b^2 = p :=
have hpu : ¬ is_unit (p : ℤ[i]), from mt norm_eq_one_iff.2 $
by rw [norm_nat_cast, int.nat_abs_mul, nat.mul_eq_one_iff];
exact λ h, (ne_of_lt hp.one_lt).symm h.1,
have hab : ∃ a b, (p : ℤ[i]) = a * b ∧ ¬ is_unit a ∧ ¬ is_unit b,
by simpa [irreducible, hpu, classical.not_forall, not_or_distrib] using hpi,
let ⟨a, b, hpab, hau, hbu⟩ := hab in
have hnap : (norm a).nat_abs = p, from ((hp.mul_eq_prime_pow_two_iff
(mt norm_eq_one_iff.1 hau) (mt norm_eq_one_iff.1 hbu)).1 $
by rw [← int.coe_nat_inj', int.coe_nat_pow, _root_.pow_two,
← @norm_nat_cast (-1), hpab];
simp).1,
⟨a.re.nat_abs, a.im.nat_abs, by simpa [nat_abs_norm_eq, nat.pow_two] using hnap⟩
lemma prime_of_nat_prime_of_mod_four_eq_three (p : ℕ) [hp : fact p.prime] (hp3 : p % 4 = 3) :
prime (p : ℤ[i]) :=
irreducible_iff_prime.1 $ classical.by_contradiction $ λ hpi,
let ⟨a, b, hab⟩ := sum_two_squares_of_nat_prime_of_not_irreducible p hpi in
have ∀ a b : zmod 4, a^2 + b^2 ≠ p, by erw [← zmod.cast_mod_nat 4 p, hp3]; exact dec_trivial,
this a b (hab ▸ by simp)
/-- A prime natural number is prime in `ℤ[i]` if and only if it is `3` mod `4` -/
lemma prime_iff_mod_four_eq_three_of_nat_prime (p : ℕ) [hp : fact p.prime] :
prime (p : ℤ[i]) ↔ p % 4 = 3 :=
⟨mod_four_eq_three_of_nat_prime_of_prime p, prime_of_nat_prime_of_mod_four_eq_three p⟩
end gaussian_int
|
841d860b5b7b42cac8fbc32271a5867f11862fe6 | 60bf3fa4185ec5075eaea4384181bfbc7e1dc319 | /src/game/order/level02.lean | 34cc74bb604c90ab2a4aa8544f6c05ae9c36f52b | [
"Apache-2.0"
] | permissive | anrddh/real-number-game | 660f1127d03a78fd35986c771d65c3132c5f4025 | c708c4e02ec306c657e1ea67862177490db041b0 | refs/heads/master | 1,668,214,277,092 | 1,593,105,075,000 | 1,593,105,075,000 | 264,269,218 | 0 | 0 | null | 1,589,567,264,000 | 1,589,567,264,000 | null | UTF-8 | Lean | false | false | 3,172 | lean | import data.real.basic
namespace xena -- hide
/-
# Chapter 2 : Order
## Level 2
This level invites you to work out a property of the absolute value.
In Lean the absolute value of $x$ is denoted by `abs x`.
-/
/- Hint : The definition of the absolute value in mathlib:
definition abs {α : Type u} [decidable_linear_ordered_add_comm_group α] (a : α) : α := max a (-a)
-/
/-
For ease of use, a notation can be wrapped around that definition as below.
-/
notation `|` x `|` := abs x
/- Lemma
For any two real numbers $a$ and $b$, we have that
$$|ab| = |a||b|$$.
-/
theorem abs_prod (a b : ℝ) : |a * b| = |a| * |b| :=
begin
rcases lt_trichotomy a 0 with haNeg | haZero | haPos,
swap,
{ -- case a = 0
have h1 : a * b = 0, norm_num, left, exact haZero,
have h2 : | a * b | = 0, exact (is_absolute_value.abv_eq_zero abs).mpr h1,
have h3 : | a | = 0, exact (is_absolute_value.abv_eq_zero abs).mpr haZero,
rw [h2,h3], norm_num,
},
{ -- case a < 0
rcases lt_trichotomy b 0 with hbNeg | hbZero | hbPos,
swap,
{ -- case b = 0
have h1 : a * b = 0, norm_num, right, exact hbZero,
have h2 : | a * b | = 0, exact (is_absolute_value.abv_eq_zero abs).mpr h1,
have h3 : | b | = 0, exact (is_absolute_value.abv_eq_zero abs).mpr hbZero,
rw [h2,h3], norm_num,
},
{ -- case b < 0
have h1 : 0 < a * b, exact mul_pos_of_neg_of_neg haNeg hbNeg,
have h2 : | a * b | = a * b, exact abs_of_pos h1,
have h3 : | a | = - a, exact abs_of_neg haNeg,
have h4 : | b | = - b, exact abs_of_neg hbNeg,
rw [h2, h3, h4], norm_num,
},
{ -- case 0 < b
have h1 : a * b < 0, exact mul_neg_of_neg_of_pos haNeg hbPos,
have h2 : | a * b | = - (a * b), exact abs_of_neg h1,
have h3 : | a | = - a, exact abs_of_neg haNeg,
have h4 : | b | = b, exact abs_of_pos hbPos,
rw [h2, h3, h4], norm_num,
}
},
{ -- case 0 < a
rcases lt_trichotomy b 0 with hbNeg | hbZero | hbPos,
swap,
{ -- case b = 0
have h1 : a * b = 0, norm_num, right, exact hbZero,
have h2 : | a * b | = 0, exact (is_absolute_value.abv_eq_zero abs).mpr h1,
have h3 : | b | = 0, exact (is_absolute_value.abv_eq_zero abs).mpr hbZero,
rw [h2,h3], norm_num,
},
{ -- case b < 0
have h1 : a * b < 0, exact mul_neg_of_pos_of_neg haPos hbNeg,
have h2 : | a * b | = -( a * b), exact abs_of_neg h1,
have h3 : | a | = a, exact abs_of_pos haPos,
have h4 : | b | = - b, exact abs_of_neg hbNeg,
rw [h2, h3, h4], norm_num,
},
{ -- case 0 < b
have h1 : 0 < a * b, exact mul_pos haPos hbPos,
have h2 : | a * b | = a * b, exact abs_of_pos h1,
have h3 : | a | = a, exact abs_of_pos haPos,
have h4 : | b | = b, exact abs_of_pos hbPos,
rw [h2, h3, h4], -- this is enough, rw closes the refl goal
}
},
done
end
end xena --hide
|
ba527fb371b43b69093695888f347bd572ca9820 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/ring_theory/ideal/basic.lean | 2ac3ce656e5f5dfa271798b15910af1a53d2caa5 | [] | 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 | 28,340 | lean | /-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau, Chris Hughes, Mario Carneiro
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.algebra.associated
import Mathlib.linear_algebra.basic
import Mathlib.order.zorn
import Mathlib.order.atoms
import Mathlib.PostPort
universes u u_1 v w l u_2 u_3
namespace Mathlib
/-!
# Ideals over a ring
This file defines `ideal R`, the type of ideals over a commutative ring `R`.
## Implementation notes
`ideal R` is implemented using `submodule R R`, where `•` is interpreted as `*`.
## TODO
Support one-sided ideals, and ideals over non-commutative rings.
See `algebra.ring_quot` for quotients of non-commutative rings.
-/
/-- An ideal in a commutative semiring `R` is an additive submonoid `s` such that
`a * b ∈ s` whenever `b ∈ s`. If `R` is a ring, then `s` is an additive subgroup. -/
def ideal (R : Type u) [comm_semiring R] :=
submodule R R
namespace ideal
protected theorem zero_mem {α : Type u} [comm_ring α] (I : ideal α) : 0 ∈ I :=
submodule.zero_mem I
protected theorem add_mem {α : Type u} [comm_ring α] (I : ideal α) {a : α} {b : α} : a ∈ I → b ∈ I → a + b ∈ I :=
submodule.add_mem I
theorem neg_mem_iff {α : Type u} [comm_ring α] (I : ideal α) {a : α} : -a ∈ I ↔ a ∈ I :=
submodule.neg_mem_iff I
theorem add_mem_iff_left {α : Type u} [comm_ring α] (I : ideal α) {a : α} {b : α} : b ∈ I → (a + b ∈ I ↔ a ∈ I) :=
submodule.add_mem_iff_left I
theorem add_mem_iff_right {α : Type u} [comm_ring α] (I : ideal α) {a : α} {b : α} : a ∈ I → (a + b ∈ I ↔ b ∈ I) :=
submodule.add_mem_iff_right I
protected theorem sub_mem {α : Type u} [comm_ring α] (I : ideal α) {a : α} {b : α} : a ∈ I → b ∈ I → a - b ∈ I :=
submodule.sub_mem I
theorem mul_mem_left {α : Type u} [comm_ring α] (I : ideal α) (a : α) {b : α} : b ∈ I → a * b ∈ I :=
submodule.smul_mem I a
theorem mul_mem_right {α : Type u} [comm_ring α] (I : ideal α) {a : α} (b : α) (h : a ∈ I) : a * b ∈ I :=
mul_comm b a ▸ mul_mem_left I b h
end ideal
-- A separate namespace definition is needed because the variables were historically in a different order
namespace ideal
theorem ext {α : Type u} [comm_ring α] {I : ideal α} {J : ideal α} (h : ∀ (x : α), x ∈ I ↔ x ∈ J) : I = J :=
submodule.ext h
theorem eq_top_of_unit_mem {α : Type u} [comm_ring α] (I : ideal α) (x : α) (y : α) (hx : x ∈ I) (h : y * x = 1) : I = ⊤ := sorry
theorem eq_top_of_is_unit_mem {α : Type u} [comm_ring α] (I : ideal α) {x : α} (hx : x ∈ I) (h : is_unit x) : I = ⊤ :=
(fun (_a : ∃ (b : α), b * x = 1) =>
Exists.dcases_on _a fun (w : α) (h_1 : w * x = 1) => idRhs (I = ⊤) (eq_top_of_unit_mem I x w hx h_1))
(iff.mp is_unit_iff_exists_inv' h)
theorem eq_top_iff_one {α : Type u} [comm_ring α] (I : ideal α) : I = ⊤ ↔ 1 ∈ I := sorry
theorem ne_top_iff_one {α : Type u} [comm_ring α] (I : ideal α) : I ≠ ⊤ ↔ ¬1 ∈ I :=
not_congr (eq_top_iff_one I)
theorem exists_mem_ne_zero_iff_ne_bot {α : Type u} [comm_ring α] (I : ideal α) : (∃ (p : α), ∃ (H : p ∈ I), p ≠ 0) ↔ I ≠ ⊥ := sorry
theorem exists_mem_ne_zero_of_ne_bot {α : Type u} [comm_ring α] (I : ideal α) (hI : I ≠ ⊥) : ∃ (p : α), ∃ (H : p ∈ I), p ≠ 0 :=
iff.mpr (exists_mem_ne_zero_iff_ne_bot I) hI
@[simp] theorem unit_mul_mem_iff_mem {α : Type u} [comm_ring α] (I : ideal α) {x : α} {y : α} (hy : is_unit y) : y * x ∈ I ↔ x ∈ I := sorry
@[simp] theorem mul_unit_mem_iff_mem {α : Type u} [comm_ring α] (I : ideal α) {x : α} {y : α} (hy : is_unit y) : x * y ∈ I ↔ x ∈ I :=
mul_comm y x ▸ unit_mul_mem_iff_mem I hy
/-- The ideal generated by a subset of a ring -/
def span {α : Type u} [comm_ring α] (s : set α) : ideal α :=
submodule.span α s
theorem subset_span {α : Type u} [comm_ring α] {s : set α} : s ⊆ ↑(span s) :=
submodule.subset_span
theorem span_le {α : Type u} [comm_ring α] {s : set α} {I : ideal α} : span s ≤ I ↔ s ⊆ ↑I :=
submodule.span_le
theorem span_mono {α : Type u} [comm_ring α] {s : set α} {t : set α} : s ⊆ t → span s ≤ span t :=
submodule.span_mono
@[simp] theorem span_eq {α : Type u} [comm_ring α] (I : ideal α) : span ↑I = I :=
submodule.span_eq I
@[simp] theorem span_singleton_one {α : Type u} [comm_ring α] : span 1 = ⊤ :=
iff.mpr (eq_top_iff_one (span 1)) (subset_span (set.mem_singleton 1))
theorem mem_span_insert {α : Type u} [comm_ring α] {s : set α} {x : α} {y : α} : x ∈ span (insert y s) ↔ ∃ (a : α), ∃ (z : α), ∃ (H : z ∈ span s), x = a * y + z :=
submodule.mem_span_insert
theorem mem_span_insert' {α : Type u} [comm_ring α] {s : set α} {x : α} {y : α} : x ∈ span (insert y s) ↔ ∃ (a : α), x + a * y ∈ span s :=
submodule.mem_span_insert'
theorem mem_span_singleton' {α : Type u} [comm_ring α] {x : α} {y : α} : x ∈ span (singleton y) ↔ ∃ (a : α), a * y = x :=
submodule.mem_span_singleton
theorem mem_span_singleton {α : Type u} [comm_ring α] {x : α} {y : α} : x ∈ span (singleton y) ↔ y ∣ x := sorry
theorem span_singleton_le_span_singleton {α : Type u} [comm_ring α] {x : α} {y : α} : span (singleton x) ≤ span (singleton y) ↔ y ∣ x :=
iff.trans span_le (iff.trans set.singleton_subset_iff mem_span_singleton)
theorem span_singleton_eq_span_singleton {α : Type u} [integral_domain α] {x : α} {y : α} : span (singleton x) = span (singleton y) ↔ associated x y := sorry
theorem span_eq_bot {α : Type u} [comm_ring α] {s : set α} : span s = ⊥ ↔ ∀ (x : α), x ∈ s → x = 0 :=
submodule.span_eq_bot
@[simp] theorem span_singleton_eq_bot {α : Type u} [comm_ring α] {x : α} : span (singleton x) = ⊥ ↔ x = 0 :=
submodule.span_singleton_eq_bot
@[simp] theorem span_zero {α : Type u} [comm_ring α] : span 0 = ⊥ :=
eq.mpr (id (Eq._oldrec (Eq.refl (span 0 = ⊥)) (Eq.symm set.singleton_zero)))
(eq.mpr (id (Eq._oldrec (Eq.refl (span (singleton 0) = ⊥)) (propext span_singleton_eq_bot))) (Eq.refl 0))
theorem span_singleton_eq_top {α : Type u} [comm_ring α] {x : α} : span (singleton x) = ⊤ ↔ is_unit x := sorry
theorem span_singleton_mul_right_unit {α : Type u} [comm_ring α] {a : α} (h2 : is_unit a) (x : α) : span (singleton (x * a)) = span (singleton x) := sorry
theorem span_singleton_mul_left_unit {α : Type u} [comm_ring α] {a : α} (h2 : is_unit a) (x : α) : span (singleton (a * x)) = span (singleton x) := sorry
/--
The ideal generated by an arbitrary binary relation.
-/
def of_rel {α : Type u} [comm_ring α] (r : α → α → Prop) : ideal α :=
submodule.span α (set_of fun (x : α) => ∃ (a : α), ∃ (b : α), ∃ (h : r a b), x = a - b)
/-- An ideal `P` of a ring `R` is prime if `P ≠ R` and `xy ∈ P → x ∈ P ∨ y ∈ P` -/
def is_prime {α : Type u} [comm_ring α] (I : ideal α) :=
I ≠ ⊤ ∧ ∀ {x y : α}, x * y ∈ I → x ∈ I ∨ y ∈ I
theorem is_prime.mem_or_mem {α : Type u} [comm_ring α] {I : ideal α} (hI : is_prime I) {x : α} {y : α} : x * y ∈ I → x ∈ I ∨ y ∈ I :=
and.right hI
theorem is_prime.mem_or_mem_of_mul_eq_zero {α : Type u} [comm_ring α] {I : ideal α} (hI : is_prime I) {x : α} {y : α} (h : x * y = 0) : x ∈ I ∨ y ∈ I :=
and.right hI x y (Eq.symm h ▸ ideal.zero_mem I)
theorem is_prime.mem_of_pow_mem {α : Type u} [comm_ring α] {I : ideal α} (hI : is_prime I) {r : α} (n : ℕ) (H : r ^ n ∈ I) : r ∈ I :=
Nat.rec (fun (H : r ^ 0 ∈ I) => not.elim (mt (iff.mpr (eq_top_iff_one I)) (and.left hI)) H)
(fun (n : ℕ) (ih : r ^ n ∈ I → r ∈ I) (H : r ^ Nat.succ n ∈ I) => or.cases_on (is_prime.mem_or_mem hI H) id ih) n H
theorem not_is_prime_iff {α : Type u} [comm_ring α] {I : ideal α} : ¬is_prime I ↔ I = ⊤ ∨ ∃ (x : α), ∃ (H : ¬x ∈ I), ∃ (y : α), ∃ (H : ¬y ∈ I), x * y ∈ I := sorry
theorem zero_ne_one_of_proper {α : Type u} [comm_ring α] {I : ideal α} (h : I ≠ ⊤) : 0 ≠ 1 :=
fun (hz : 0 = 1) => iff.mp (ne_top_iff_one I) h (hz ▸ ideal.zero_mem I)
theorem span_singleton_prime {α : Type u} [comm_ring α] {p : α} (hp : p ≠ 0) : is_prime (span (singleton p)) ↔ prime p := sorry
theorem bot_prime {R : Type u_1} [integral_domain R] : is_prime ⊥ := sorry
/-- An ideal is maximal if it is maximal in the collection of proper ideals. -/
def is_maximal {α : Type u} [comm_ring α] (I : ideal α) :=
is_coatom I
theorem is_maximal_iff {α : Type u} [comm_ring α] {I : ideal α} : is_maximal I ↔ ¬1 ∈ I ∧ ∀ (J : ideal α) (x : α), I ≤ J → ¬x ∈ I → x ∈ J → 1 ∈ J := sorry
theorem is_maximal.eq_of_le {α : Type u} [comm_ring α] {I : ideal α} {J : ideal α} (hI : is_maximal I) (hJ : J ≠ ⊤) (IJ : I ≤ J) : I = J :=
iff.mpr eq_iff_le_not_lt { left := IJ, right := fun (h : I < J) => hJ (and.right hI J h) }
theorem is_maximal.exists_inv {α : Type u} [comm_ring α] {I : ideal α} (hI : is_maximal I) {x : α} (hx : ¬x ∈ I) : ∃ (y : α), y * x - 1 ∈ I := sorry
theorem is_maximal.is_prime {α : Type u} [comm_ring α] {I : ideal α} (H : is_maximal I) : is_prime I := sorry
protected instance is_maximal.is_prime' {α : Type u} [comm_ring α] (I : ideal α) [H : is_maximal I] : is_prime I :=
is_maximal.is_prime
/-- Krull's theorem: if `I` is an ideal that is not the whole ring, then it is included in some
maximal ideal. -/
theorem exists_le_maximal {α : Type u} [comm_ring α] (I : ideal α) (hI : I ≠ ⊤) : ∃ (M : ideal α), is_maximal M ∧ I ≤ M := sorry
/-- Krull's theorem: a nontrivial ring has a maximal ideal. -/
theorem exists_maximal {α : Type u} [comm_ring α] [nontrivial α] : ∃ (M : ideal α), is_maximal M := sorry
/-- If P is not properly contained in any maximal ideal then it is not properly contained
in any proper ideal -/
theorem maximal_of_no_maximal {R : Type u} [comm_ring R] {P : ideal R} (hmax : ∀ (m : ideal R), P < m → ¬is_maximal m) (J : ideal R) (hPJ : P < J) : J = ⊤ := sorry
theorem mem_span_pair {α : Type u} [comm_ring α] {x : α} {y : α} {z : α} : z ∈ span (insert x (singleton y)) ↔ ∃ (a : α), ∃ (b : α), a * x + b * y = z := sorry
theorem span_singleton_lt_span_singleton {β : Type v} [integral_domain β] {x : β} {y : β} : span (singleton x) < span (singleton y) ↔ dvd_not_unit y x := sorry
theorem factors_decreasing {β : Type v} [integral_domain β] (b₁ : β) (b₂ : β) (h₁ : b₁ ≠ 0) (h₂ : ¬is_unit b₂) : span (singleton (b₁ * b₂)) < span (singleton b₁) := sorry
/-- The quotient `R/I` of a ring `R` by an ideal `I`. -/
def quotient {α : Type u} [comm_ring α] (I : ideal α) :=
submodule.quotient I
namespace quotient
protected instance has_one {α : Type u} [comm_ring α] (I : ideal α) : HasOne (quotient I) :=
{ one := submodule.quotient.mk 1 }
protected instance has_mul {α : Type u} [comm_ring α] (I : ideal α) : Mul (quotient I) :=
{ mul := fun (a b : quotient I) => quotient.lift_on₂' a b (fun (a b : α) => submodule.quotient.mk (a * b)) sorry }
protected instance comm_ring {α : Type u} [comm_ring α] (I : ideal α) : comm_ring (quotient I) :=
comm_ring.mk add_comm_group.add sorry add_comm_group.zero sorry sorry add_comm_group.neg add_comm_group.sub sorry sorry
Mul.mul sorry 1 sorry sorry sorry sorry sorry
/-- The ring homomorphism from a ring `R` to a quotient ring `R/I`. -/
def mk {α : Type u} [comm_ring α] (I : ideal α) : α →+* quotient I :=
ring_hom.mk (fun (a : α) => submodule.quotient.mk a) sorry sorry sorry sorry
protected instance inhabited {α : Type u} [comm_ring α] {I : ideal α} : Inhabited (quotient I) :=
{ default := coe_fn (mk I) (bit1 (bit0 (bit1 (bit0 (bit0 1))))) }
protected theorem eq {α : Type u} [comm_ring α] {I : ideal α} {x : α} {y : α} : coe_fn (mk I) x = coe_fn (mk I) y ↔ x - y ∈ I :=
submodule.quotient.eq I
@[simp] theorem mk_eq_mk {α : Type u} [comm_ring α] {I : ideal α} (x : α) : submodule.quotient.mk x = coe_fn (mk I) x :=
rfl
theorem eq_zero_iff_mem {α : Type u} {a : α} [comm_ring α] {I : ideal α} : coe_fn (mk I) a = 0 ↔ a ∈ I := sorry
theorem zero_eq_one_iff {α : Type u} [comm_ring α] {I : ideal α} : 0 = 1 ↔ I = ⊤ :=
iff.trans eq_comm (iff.trans eq_zero_iff_mem (iff.symm (eq_top_iff_one I)))
theorem zero_ne_one_iff {α : Type u} [comm_ring α] {I : ideal α} : 0 ≠ 1 ↔ I ≠ ⊤ :=
not_congr zero_eq_one_iff
protected theorem nontrivial {α : Type u} [comm_ring α] {I : ideal α} (hI : I ≠ ⊤) : nontrivial (quotient I) :=
nontrivial.mk (Exists.intro 0 (Exists.intro 1 (iff.mpr zero_ne_one_iff hI)))
theorem mk_surjective {α : Type u} [comm_ring α] {I : ideal α} : function.surjective ⇑(mk I) :=
fun (y : quotient I) => quotient.induction_on' y fun (x : α) => exists.intro x rfl
protected instance integral_domain {α : Type u} [comm_ring α] (I : ideal α) [hI : is_prime I] : integral_domain (quotient I) :=
integral_domain.mk comm_ring.add sorry comm_ring.zero sorry sorry comm_ring.neg comm_ring.sub sorry sorry comm_ring.mul
sorry comm_ring.one sorry sorry sorry sorry sorry sorry sorry
theorem is_integral_domain_iff_prime {α : Type u} [comm_ring α] (I : ideal α) : is_integral_domain (quotient I) ↔ is_prime I := sorry
theorem exists_inv {α : Type u} [comm_ring α] {I : ideal α} [hI : is_maximal I] {a : quotient I} : a ≠ 0 → ∃ (b : quotient I), a * b = 1 := sorry
/-- quotient by maximal ideal is a field. def rather than instance, since users will have
computable inverses in some applications -/
protected def field {α : Type u} [comm_ring α] (I : ideal α) [hI : is_maximal I] : field (quotient I) :=
field.mk integral_domain.add sorry integral_domain.zero sorry sorry integral_domain.neg integral_domain.sub sorry sorry
integral_domain.mul sorry integral_domain.one sorry sorry sorry sorry sorry
(fun (a : quotient I) => dite (a = 0) (fun (ha : a = 0) => 0) fun (ha : ¬a = 0) => classical.some (exists_inv ha))
sorry sorry sorry
/-- If the quotient by an ideal is a field, then the ideal is maximal. -/
theorem maximal_of_is_field {α : Type u} [comm_ring α] (I : ideal α) (hqf : is_field (quotient I)) : is_maximal I := sorry
/-- The quotient of a ring by an ideal is a field iff the ideal is maximal. -/
theorem maximal_ideal_iff_is_field_quotient {α : Type u} [comm_ring α] (I : ideal α) : is_maximal I ↔ is_field (quotient I) :=
{ mp := fun (h : is_maximal I) => field.to_is_field (quotient I),
mpr := fun (h : is_field (quotient I)) => maximal_of_is_field I h }
/-- Given a ring homomorphism `f : α →+* β` sending all elements of an ideal to zero,
lift it to the quotient by this ideal. -/
def lift {α : Type u} {β : Type v} [comm_ring α] [comm_ring β] (S : ideal α) (f : α →+* β) (H : ∀ (a : α), a ∈ S → coe_fn f a = 0) : quotient S →+* β :=
ring_hom.mk (fun (x : quotient S) => quotient.lift_on' x ⇑f sorry) sorry sorry sorry sorry
@[simp] theorem lift_mk {α : Type u} {β : Type v} {a : α} [comm_ring α] [comm_ring β] (S : ideal α) (f : α →+* β) (H : ∀ (a : α), a ∈ S → coe_fn f a = 0) : coe_fn (lift S f H) (coe_fn (mk S) a) = coe_fn f a :=
rfl
@[simp] theorem lift_comp_mk {α : Type u} {β : Type v} [comm_ring α] [comm_ring β] (S : ideal α) (f : α →+* β) (H : ∀ (a : α), a ∈ S → coe_fn f a = 0) : ring_hom.comp (lift S f H) (mk S) = f :=
ring_hom.ext fun (_x : α) => rfl
theorem lift_surjective {α : Type u} {β : Type v} [comm_ring α] [comm_ring β] (S : ideal α) (f : α →+* β) (H : ∀ (a : α), a ∈ S → coe_fn f a = 0) (hf : function.surjective ⇑f) : function.surjective ⇑(lift S f H) := sorry
end quotient
theorem mem_sup_left {R : Type u} [comm_ring R] {S : ideal R} {T : ideal R} {x : R} : x ∈ S → x ∈ S ⊔ T :=
(fun (this : S ≤ S ⊔ T) => this) le_sup_left
theorem mem_sup_right {R : Type u} [comm_ring R] {S : ideal R} {T : ideal R} {x : R} : x ∈ T → x ∈ S ⊔ T :=
(fun (this : T ≤ S ⊔ T) => this) le_sup_right
theorem mem_supr_of_mem {R : Type u} [comm_ring R] {ι : Type u_1} {S : ι → ideal R} (i : ι) {x : R} : x ∈ S i → x ∈ supr S :=
(fun (this : S i ≤ supr S) => this) (le_supr S i)
theorem mem_Sup_of_mem {R : Type u} [comm_ring R] {S : set (ideal R)} {s : ideal R} (hs : s ∈ S) {x : R} : x ∈ s → x ∈ Sup S :=
(fun (this : s ≤ Sup S) => this) (le_Sup hs)
theorem mem_Inf {R : Type u} [comm_ring R] {s : set (ideal R)} {x : R} : x ∈ Inf s ↔ ∀ {I : ideal R}, I ∈ s → x ∈ I := sorry
@[simp] theorem mem_inf {R : Type u} [comm_ring R] {I : ideal R} {J : ideal R} {x : R} : x ∈ I ⊓ J ↔ x ∈ I ∧ x ∈ J :=
iff.rfl
@[simp] theorem mem_infi {R : Type u} [comm_ring R] {ι : Type u_1} {I : ι → ideal R} {x : R} : x ∈ infi I ↔ ∀ (i : ι), x ∈ I i :=
submodule.mem_infi fun (i : ι) => I i
@[simp] theorem mem_bot {R : Type u} [comm_ring R] {x : R} : x ∈ ⊥ ↔ x = 0 :=
submodule.mem_bot R
/-- All ideals in a field are trivial. -/
theorem eq_bot_or_top {K : Type u} [field K] (I : ideal K) : I = ⊥ ∨ I = ⊤ := sorry
theorem eq_bot_of_prime {K : Type u} [field K] (I : ideal K) [h : is_prime I] : I = ⊥ :=
iff.mp or_iff_not_imp_right (eq_bot_or_top I) (and.left h)
theorem bot_is_maximal {K : Type u} [field K] : is_maximal ⊥ := sorry
/-- `I^n` as an ideal of `R^n`. -/
def pi {α : Type u} [comm_ring α] (I : ideal α) (ι : Type v) : ideal (ι → α) :=
submodule.mk (set_of fun (x : ι → α) => ∀ (i : ι), x i ∈ I) sorry sorry sorry
theorem mem_pi {α : Type u} [comm_ring α] (I : ideal α) (ι : Type v) (x : ι → α) : x ∈ pi I ι ↔ ∀ (i : ι), x i ∈ I :=
iff.rfl
/-- `R^n/I^n` is a `R/I`-module. -/
protected instance module_pi {α : Type u} [comm_ring α] (I : ideal α) (ι : Type v) : module (quotient I) (quotient (pi I ι)) :=
semimodule.mk sorry sorry
/-- `R^n/I^n` is isomorphic to `(R/I)^n` as an `R/I`-module. -/
def pi_quot_equiv {α : Type u} [comm_ring α] (I : ideal α) (ι : Type v) : linear_equiv (quotient I) (quotient (pi I ι)) (ι → quotient I) :=
linear_equiv.mk
(fun (x : quotient (pi I ι)) => quotient.lift_on' x (fun (f : ι → α) (i : ι) => coe_fn (quotient.mk I) (f i)) sorry)
sorry sorry (fun (x : ι → quotient I) => coe_fn (quotient.mk (pi I ι)) fun (i : ι) => quotient.out' (x i)) sorry sorry
/-- If `f : R^n → R^m` is an `R`-linear map and `I ⊆ R` is an ideal, then the image of `I^n` is
contained in `I^m`. -/
theorem map_pi {α : Type u} [comm_ring α] (I : ideal α) {ι : Type u_1} [fintype ι] {ι' : Type w} (x : ι → α) (hi : ∀ (i : ι), x i ∈ I) (f : linear_map α (ι → α) (ι' → α)) (i : ι') : coe_fn f x i ∈ I := sorry
end ideal
namespace ring
theorem not_is_field_of_subsingleton {R : Type u_1} [ring R] [subsingleton R] : ¬is_field R := sorry
theorem exists_not_is_unit_of_not_is_field {R : Type u_1} [comm_ring R] [nontrivial R] (hf : ¬is_field R) : ∃ (x : R), ∃ (H : x ≠ 0), ¬is_unit x := sorry
theorem not_is_field_iff_exists_ideal_bot_lt_and_lt_top {R : Type u_1} [comm_ring R] [nontrivial R] : ¬is_field R ↔ ∃ (I : ideal R), ⊥ < I ∧ I < ⊤ := sorry
theorem not_is_field_iff_exists_prime {R : Type u_1} [comm_ring R] [nontrivial R] : ¬is_field R ↔ ∃ (p : ideal R), p ≠ ⊥ ∧ ideal.is_prime p := sorry
/-- When a ring is not a field, the maximal ideals are nontrivial. -/
theorem ne_bot_of_is_maximal_of_not_is_field {R : Type u_1} [comm_ring R] [nontrivial R] {M : ideal R} (max : ideal.is_maximal M) (not_field : ¬is_field R) : M ≠ ⊥ := sorry
end ring
namespace ideal
/-- Maximal ideals in a non-field are nontrivial. -/
theorem bot_lt_of_maximal {R : Type u} [comm_ring R] [nontrivial R] (M : ideal R) [hm : is_maximal M] (non_field : ¬is_field R) : ⊥ < M := sorry
end ideal
/-- The set of non-invertible elements of a monoid. -/
def nonunits (α : Type u) [monoid α] : set α :=
set_of fun (a : α) => ¬is_unit a
@[simp] theorem mem_nonunits_iff {α : Type u} {a : α} [comm_monoid α] : a ∈ nonunits α ↔ ¬is_unit a :=
iff.rfl
theorem mul_mem_nonunits_right {α : Type u} {a : α} {b : α} [comm_monoid α] : b ∈ nonunits α → a * b ∈ nonunits α :=
mt is_unit_of_mul_is_unit_right
theorem mul_mem_nonunits_left {α : Type u} {a : α} {b : α} [comm_monoid α] : a ∈ nonunits α → a * b ∈ nonunits α :=
mt is_unit_of_mul_is_unit_left
theorem zero_mem_nonunits {α : Type u} [semiring α] : 0 ∈ nonunits α ↔ 0 ≠ 1 :=
not_congr is_unit_zero_iff
@[simp] theorem one_not_mem_nonunits {α : Type u} [monoid α] : ¬1 ∈ nonunits α :=
not_not_intro is_unit_one
theorem coe_subset_nonunits {α : Type u} [comm_ring α] {I : ideal α} (h : I ≠ ⊤) : ↑I ⊆ nonunits α :=
fun (x : α) (hx : x ∈ ↑I) (hu : is_unit x) => h (ideal.eq_top_of_is_unit_mem I hx hu)
theorem exists_max_ideal_of_mem_nonunits {α : Type u} {a : α} [comm_ring α] (h : a ∈ nonunits α) : ∃ (I : ideal α), ideal.is_maximal I ∧ a ∈ I := sorry
/-- A commutative ring is local if it has a unique maximal ideal. Note that
`local_ring` is a predicate. -/
class local_ring (α : Type u) [comm_ring α]
extends nontrivial α
where
is_local : ∀ (a : α), is_unit a ∨ is_unit (1 - a)
namespace local_ring
theorem is_unit_or_is_unit_one_sub_self {α : Type u} [comm_ring α] [local_ring α] (a : α) : is_unit a ∨ is_unit (1 - a) :=
is_local a
theorem is_unit_of_mem_nonunits_one_sub_self {α : Type u} [comm_ring α] [local_ring α] (a : α) (h : 1 - a ∈ nonunits α) : is_unit a :=
iff.mp or_iff_not_imp_right (is_local a) h
theorem is_unit_one_sub_self_of_mem_nonunits {α : Type u} [comm_ring α] [local_ring α] (a : α) (h : a ∈ nonunits α) : is_unit (1 - a) :=
iff.mp or_iff_not_imp_left (is_local a) h
theorem nonunits_add {α : Type u} [comm_ring α] [local_ring α] {x : α} {y : α} (hx : x ∈ nonunits α) (hy : y ∈ nonunits α) : x + y ∈ nonunits α := sorry
/-- The ideal of elements that are not units. -/
def maximal_ideal (α : Type u) [comm_ring α] [local_ring α] : ideal α :=
submodule.mk (nonunits α) sorry sorry sorry
protected instance maximal_ideal.is_maximal (α : Type u) [comm_ring α] [local_ring α] : ideal.is_maximal (maximal_ideal α) :=
eq.mpr (id (Eq._oldrec (Eq.refl (ideal.is_maximal (maximal_ideal α))) (propext ideal.is_maximal_iff)))
{ left := id fun (h : 1 ∈ maximal_ideal α) => h is_unit_one,
right :=
fun (I : ideal α) (x : α) (hI : maximal_ideal α ≤ I) (hx : ¬x ∈ maximal_ideal α) (H : x ∈ I) =>
Exists.dcases_on (eq.mp (Eq._oldrec (Eq.refl (¬x ∈ maximal_ideal α)) (propext not_not)) hx)
fun (u : units α) (hx_h : ↑u = x) =>
Eq._oldrec
(fun (H : ↑u ∈ I) =>
eq.mpr (id (Eq.refl (1 ∈ I)))
(eq.mp
((fun (ᾰ ᾰ_1 : α) (e_2 : ᾰ = ᾰ_1) (ᾰ_2 ᾰ_3 : ideal α) (e_3 : ᾰ_2 = ᾰ_3) =>
congr (congr_arg has_mem.mem e_2) e_3)
(↑(u⁻¹) * ↑u) 1 (units.inv_mul u) I I (Eq.refl I))
(ideal.mul_mem_left I (↑(u⁻¹)) H)))
hx_h H }
theorem maximal_ideal_unique (α : Type u) [comm_ring α] [local_ring α] : exists_unique fun (I : ideal α) => ideal.is_maximal I := sorry
theorem eq_maximal_ideal {α : Type u} [comm_ring α] [local_ring α] {I : ideal α} (hI : ideal.is_maximal I) : I = maximal_ideal α :=
unique_of_exists_unique (maximal_ideal_unique α) hI (maximal_ideal.is_maximal α)
theorem le_maximal_ideal {α : Type u} [comm_ring α] [local_ring α] {J : ideal α} (hJ : J ≠ ⊤) : J ≤ maximal_ideal α := sorry
@[simp] theorem mem_maximal_ideal {α : Type u} [comm_ring α] [local_ring α] (x : α) : x ∈ maximal_ideal α ↔ x ∈ nonunits α :=
iff.rfl
end local_ring
theorem local_of_nonunits_ideal {α : Type u} [comm_ring α] (hnze : 0 ≠ 1) (h : ∀ (x y : α), x ∈ nonunits α → y ∈ nonunits α → x + y ∈ nonunits α) : local_ring α := sorry
theorem local_of_unique_max_ideal {α : Type u} [comm_ring α] (h : exists_unique fun (I : ideal α) => ideal.is_maximal I) : local_ring α := sorry
theorem local_of_unique_nonzero_prime (R : Type u) [comm_ring R] (h : exists_unique fun (P : ideal R) => P ≠ ⊥ ∧ ideal.is_prime P) : local_ring R := sorry
theorem local_of_surjective {A : Type u_1} {B : Type u_2} [comm_ring A] [local_ring A] [comm_ring B] [nontrivial B] (f : A →+* B) (hf : function.surjective ⇑f) : local_ring B := sorry
/-- A local ring homomorphism is a homomorphism between local rings
such that the image of the maximal ideal of the source is contained within
the maximal ideal of the target. -/
class is_local_ring_hom {α : Type u} {β : Type v} [semiring α] [semiring β] (f : α →+* β)
where
map_nonunit : ∀ (a : α), is_unit (coe_fn f a) → is_unit a
protected instance is_local_ring_hom_id (A : Type u_1) [semiring A] : is_local_ring_hom (ring_hom.id A) :=
is_local_ring_hom.mk fun (a : A) => id
@[simp] theorem is_unit_map_iff {A : Type u_1} {B : Type u_2} [semiring A] [semiring B] (f : A →+* B) [is_local_ring_hom f] (a : A) : is_unit (coe_fn f a) ↔ is_unit a :=
{ mp := is_local_ring_hom.map_nonunit a, mpr := ring_hom.is_unit_map f }
protected instance is_local_ring_hom_comp {A : Type u_1} {B : Type u_2} {C : Type u_3} [semiring A] [semiring B] [semiring C] (g : B →+* C) (f : A →+* B) [is_local_ring_hom g] [is_local_ring_hom f] : is_local_ring_hom (ring_hom.comp g f) :=
is_local_ring_hom.mk fun (a : A) => is_local_ring_hom.map_nonunit a ∘ is_local_ring_hom.map_nonunit (coe_fn f a)
@[simp] theorem is_unit_of_map_unit {α : Type u} {β : Type v} [semiring α] [semiring β] (f : α →+* β) [is_local_ring_hom f] (a : α) (h : is_unit (coe_fn f a)) : is_unit a :=
is_local_ring_hom.map_nonunit a h
theorem of_irreducible_map {α : Type u} {β : Type v} [semiring α] [semiring β] (f : α →+* β) [h : is_local_ring_hom f] {x : α} (hfx : irreducible (coe_fn f x)) : irreducible x := sorry
theorem map_nonunit {α : Type u} {β : Type v} [comm_ring α] [local_ring α] [comm_ring β] [local_ring β] (f : α →+* β) [is_local_ring_hom f] (a : α) (h : a ∈ local_ring.maximal_ideal α) : coe_fn f a ∈ local_ring.maximal_ideal β :=
fun (H : is_unit (coe_fn f a)) => h (is_unit_of_map_unit f a H)
namespace local_ring
/-- The residue field of a local ring is the quotient of the ring by its maximal ideal. -/
def residue_field (α : Type u) [comm_ring α] [local_ring α] :=
ideal.quotient (maximal_ideal α)
protected instance residue_field.field (α : Type u) [comm_ring α] [local_ring α] : field (residue_field α) :=
ideal.quotient.field (maximal_ideal α)
protected instance residue_field.inhabited (α : Type u) [comm_ring α] [local_ring α] : Inhabited (residue_field α) :=
{ default := bit1 (bit0 (bit1 (bit0 (bit0 1)))) }
/-- The quotient map from a local ring to its residue field. -/
def residue (α : Type u) [comm_ring α] [local_ring α] : α →+* residue_field α :=
ideal.quotient.mk (maximal_ideal α)
namespace residue_field
/-- The map on residue fields induced by a local homomorphism between local rings -/
def map {α : Type u} {β : Type v} [comm_ring α] [local_ring α] [comm_ring β] [local_ring β] (f : α →+* β) [is_local_ring_hom f] : residue_field α →+* residue_field β :=
ideal.quotient.lift (maximal_ideal α) (ring_hom.comp (ideal.quotient.mk (maximal_ideal β)) f) sorry
end residue_field
end local_ring
namespace field
protected instance local_ring {α : Type u} [field α] : local_ring α :=
local_ring.mk
fun (a : α) =>
dite (a = 0)
(fun (h : a = 0) =>
Or.inr
(eq.mpr (id (Eq._oldrec (Eq.refl (is_unit (1 - a))) h))
(eq.mpr (id (Eq._oldrec (Eq.refl (is_unit (1 - 0))) (sub_zero 1))) is_unit_one)))
fun (h : ¬a = 0) => Or.inl (is_unit_of_mul_eq_one a (a⁻¹) (div_self h))
|
cf2bfa2e571b4d44194d7fd45ed1c9d3f8bcabf1 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/category_theory/action.lean | 54a4f8a2135ad05b443961830a677b9116c3309d | [] | 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 | 4,163 | lean | /-
Copyright (c) 2020 David Wärn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: David Wärn
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.category_theory.elements
import Mathlib.category_theory.single_obj
import Mathlib.group_theory.group_action.basic
import Mathlib.PostPort
universes u u_1
namespace Mathlib
/-!
# Actions as functors and as categories
From a multiplicative action M ↻ X, we can construct a functor from M to the category of
types, mapping the single object of M to X and an element `m : M` to map `X → X` given by
multiplication by `m`.
This functor induces a category structure on X -- a special case of the category of elements.
A morphism `x ⟶ y` in this category is simply a scalar `m : M` such that `m • x = y`. In the case
where M is a group, this category is a groupoid -- the `action groupoid'.
-/
namespace category_theory
/-- A multiplicative action M ↻ X viewed as a functor mapping the single object of M to X
and an element `m : M` to the map `X → X` given by multiplication by `m`. -/
@[simp] theorem action_as_functor_obj (M : Type u_1) [monoid M] (X : Type u) [mul_action M X] (_x : single_obj M) : functor.obj (action_as_functor M X) _x = X :=
Eq.refl (functor.obj (action_as_functor M X) _x)
/-- A multiplicative action M ↻ X induces a category strucure on X, where a morphism
from x to y is a scalar taking x to y. Due to implementation details, the object type
of this category is not equal to X, but is in bijection with X. -/
def action_category (M : Type u_1) [monoid M] (X : Type u) [mul_action M X] :=
functor.elements (action_as_functor M X)
namespace action_category
protected instance category_theory.groupoid (X : Type u) (G : Type u_1) [group G] [mul_action G X] : groupoid (action_category G X) :=
category_theory.groupoid_of_elements (action_as_functor G X)
/-- The projection from the action category to the monoid, mapping a morphism to its
label. -/
def π (M : Type u_1) [monoid M] (X : Type u) [mul_action M X] : action_category M X ⥤ single_obj M :=
category_of_elements.π (action_as_functor M X)
@[simp] theorem π_map (M : Type u_1) [monoid M] (X : Type u) [mul_action M X] (p : action_category M X) (q : action_category M X) (f : p ⟶ q) : functor.map (π M X) f = subtype.val f :=
rfl
@[simp] theorem π_obj (M : Type u_1) [monoid M] (X : Type u) [mul_action M X] (p : action_category M X) : functor.obj (π M X) p = single_obj.star M :=
subsingleton.elim (functor.obj (π M X) p) (single_obj.star M)
/-- An object of the action category given by M ↻ X corresponds to an element of X. -/
def obj_equiv (M : Type u_1) [monoid M] (X : Type u) [mul_action M X] : X ≃ action_category M X :=
equiv.mk (fun (x : X) => sigma.mk (single_obj.star M) x) (fun (p : action_category M X) => sigma.snd p) sorry sorry
theorem hom_as_subtype (M : Type u_1) [monoid M] (X : Type u) [mul_action M X] (p : action_category M X) (q : action_category M X) : (p ⟶ q) = Subtype fun (m : M) => m • coe_fn (equiv.symm (obj_equiv M X)) p = coe_fn (equiv.symm (obj_equiv M X)) q :=
rfl
protected instance inhabited (M : Type u_1) [monoid M] (X : Type u) [mul_action M X] [Inhabited X] : Inhabited (action_category M X) :=
{ default := coe_fn (obj_equiv M X) Inhabited.default }
/-- The stabilizer of a point is isomorphic to the endomorphism monoid at the
corresponding point. In fact they are definitionally equivalent. -/
def stabilizer_iso_End (M : Type u_1) [monoid M] {X : Type u} [mul_action M X] (x : X) : ↥(mul_action.stabilizer.submonoid M x) ≃* End (coe_fn (obj_equiv M X) x) :=
mul_equiv.refl ↥(mul_action.stabilizer.submonoid M x)
@[simp] theorem stabilizer_iso_End_apply (M : Type u_1) [monoid M] {X : Type u} [mul_action M X] (x : X) (f : ↥(mul_action.stabilizer.submonoid M x)) : mul_equiv.to_fun (stabilizer_iso_End M x) f = f :=
rfl
@[simp] theorem stabilizer_iso_End_symm_apply (M : Type u_1) [monoid M] {X : Type u} [mul_action M X] (x : X) (f : End (coe_fn (obj_equiv M X) x)) : mul_equiv.inv_fun (stabilizer_iso_End M x) f = f :=
rfl
|
7258ed91854cb939b8f337add842d60602e049e6 | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/data/polynomial/denoms_clearable.lean | fe03f8eea413bb01f0cc05e622e2464aef41f589 | [
"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 | 4,660 | lean | /-
Copyright (c) 2020 Damiano Testa. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Damiano Testa
-/
import data.polynomial.erase_lead
/-!
# Denominators of evaluation of polynomials at ratios
Let `i : R → K` be a homomorphism of semirings. Assume that `K` is commutative. If `a` and
`b` are elements of `R` such that `i b ∈ K` is invertible, then for any polynomial
`f ∈ polynomial R` the "mathematical" expression `b ^ f.nat_degree * f (a / b) ∈ K` is in
the image of the homomorphism `i`.
-/
open polynomial finset
section denoms_clearable
variables {R K : Type*} [semiring R] [comm_semiring K] {i : R →+* K}
variables {a b : R} {bi : K}
-- TODO: use hypothesis (ub : is_unit (i b)) to work with localizations.
/-- `denoms_clearable` formalizes the property that `b ^ N * f (a / b)`
does not have denominators, if the inequality `f.nat_degree ≤ N` holds.
The definition asserts the existence of an element `D` of `R` and an
element `bi = 1 / i b` of `K` such that clearing the denominators of
the fraction equals `i D`.
-/
def denoms_clearable (a b : R) (N : ℕ) (f : polynomial R) (i : R →+* K) : Prop :=
∃ (D : R) (bi : K), bi * i b = 1 ∧ i D = i b ^ N * eval (i a * bi) (f.map i)
lemma denoms_clearable_zero (N : ℕ) (a : R) (bu : bi * i b = 1) :
denoms_clearable a b N 0 i :=
⟨0, bi, bu, by simp only [eval_zero, ring_hom.map_zero, mul_zero, map_zero]⟩
lemma denoms_clearable_C_mul_X_pow {N : ℕ} (a : R) (bu : bi * i b = 1) {n : ℕ} (r : R)
(nN : n ≤ N) : denoms_clearable a b N (C r * X ^ n) i :=
begin
refine ⟨r * a ^ n * b ^ (N - n), bi, bu, _⟩,
rw [C_mul_X_pow_eq_monomial, map_monomial, ← C_mul_X_pow_eq_monomial, eval_mul, eval_pow, eval_C],
rw [ring_hom.map_mul, ring_hom.map_mul, ring_hom.map_pow, ring_hom.map_pow, eval_X, mul_comm],
rw [← nat.sub_add_cancel nN] {occs := occurrences.pos [2]},
rw [pow_add, mul_assoc, mul_comm (i b ^ n), mul_pow, mul_assoc, mul_assoc (i a ^ n), ← mul_pow],
rw [bu, one_pow, mul_one],
end
lemma denoms_clearable.add {N : ℕ} {f g : polynomial R} :
denoms_clearable a b N f i → denoms_clearable a b N g i → denoms_clearable a b N (f + g) i :=
λ ⟨Df, bf, bfu, Hf⟩ ⟨Dg, bg, bgu, Hg⟩, ⟨Df + Dg, bf, bfu,
begin
rw [ring_hom.map_add, polynomial.map_add, eval_add, mul_add, Hf, Hg],
congr,
refine @inv_unique K _ (i b) bg bf _ _;
rwa mul_comm,
end ⟩
lemma denoms_clearable_of_nat_degree_le (N : ℕ) (a : R) (bu : bi * i b = 1) :
∀ (f : polynomial R), f.nat_degree ≤ N → denoms_clearable a b N f i :=
induction_with_nat_degree_le N
(denoms_clearable_zero N a bu)
(λ N_1 r r0, denoms_clearable_C_mul_X_pow a bu r)
(λ f g fN gN df dg, df.add dg)
/-- If `i : R → K` is a ring homomorphism, `f` is a polynomial with coefficients in `R`,
`a, b` are elements of `R`, with `i b` invertible, then there is a `D ∈ R` such that
`b ^ f.nat_degree * f (a / b)` equals `i D`. -/
theorem denoms_clearable_nat_degree
(i : R →+* K) (f : polynomial R) (a : R) (bu : bi * i b = 1) :
denoms_clearable a b f.nat_degree f i :=
denoms_clearable_of_nat_degree_le f.nat_degree a bu f le_rfl
end denoms_clearable
open ring_hom
/-- Evaluating a polynomial with integer coefficients at a rational number and clearing
denominators, yields a number greater than or equal to one. The target can be any
`linear_ordered_field K`.
The assumption on `K` could be weakened to `linear_ordered_comm_ring` assuming that the
image of the denominator is invertible in `K`. -/
lemma one_le_pow_mul_abs_eval_div {K : Type*} [linear_ordered_field K] {f : polynomial ℤ}
{a b : ℤ} (b0 : 0 < b) (fab : eval ((a : K) / b) (f.map (algebra_map ℤ K)) ≠ 0) :
(1 : K) ≤ b ^ f.nat_degree * abs (eval ((a : K) / b) (f.map (algebra_map ℤ K))) :=
begin
obtain ⟨ev, bi, bu, hF⟩ := @denoms_clearable_nat_degree _ _ _ _ b _ (algebra_map ℤ K)
f a (by { rw [eq_int_cast, one_div_mul_cancel], rw [int.cast_ne_zero], exact (b0.ne.symm) }),
obtain Fa := congr_arg abs hF,
rw [eq_one_div_of_mul_eq_one_left bu, eq_int_cast, eq_int_cast, abs_mul] at Fa,
rw [abs_of_pos (pow_pos (int.cast_pos.mpr b0) _ : 0 < (b : K) ^ _), one_div, eq_int_cast] at Fa,
rw [div_eq_mul_inv, ← Fa, ← int.cast_abs, ← int.cast_one, int.cast_le],
refine int.le_of_lt_add_one ((lt_add_iff_pos_left 1).mpr (abs_pos.mpr (λ F0, fab _))),
rw [eq_one_div_of_mul_eq_one_left bu, F0, one_div, eq_int_cast, int.cast_zero, zero_eq_mul] at hF,
cases hF with hF hF,
{ exact (not_le.mpr b0 (le_of_eq (int.cast_eq_zero.mp (pow_eq_zero hF)))).elim },
{ rwa div_eq_mul_inv }
end
|
1f8889df30f9029c8bb3d453dfc002f149cd60f2 | 432d948a4d3d242fdfb44b81c9e1b1baacd58617 | /src/category_theory/limits/shapes/kernels.lean | ee8e7173d5f4fa7a9471bdc9c6c153e71bfeae10 | [
"Apache-2.0"
] | permissive | JLimperg/aesop3 | 306cc6570c556568897ed2e508c8869667252e8a | a4a116f650cc7403428e72bd2e2c4cda300fe03f | refs/heads/master | 1,682,884,916,368 | 1,620,320,033,000 | 1,620,320,033,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 26,672 | lean | /-
Copyright (c) 2019 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison, Markus Himmel
-/
import category_theory.limits.shapes.zero
/-!
# Kernels and cokernels
In a category with zero morphisms, the kernel of a morphism `f : X ⟶ Y` is
the equalizer of `f` and `0 : X ⟶ Y`. (Similarly the cokernel is the coequalizer.)
The basic definitions are
* `kernel : (X ⟶ Y) → C`
* `kernel.ι : kernel f ⟶ X`
* `kernel.condition : kernel.ι f ≫ f = 0` and
* `kernel.lift (k : W ⟶ X) (h : k ≫ f = 0) : W ⟶ kernel f` (as well as the dual versions)
## Main statements
Besides the definition and lifts, we prove
* `kernel.ι_zero_is_iso`: a kernel map of a zero morphism is an isomorphism
* `kernel.eq_zero_of_epi_kernel`: if `kernel.ι f` is an epimorphism, then `f = 0`
* `kernel.of_mono`: the kernel of a monomorphism is the zero object
* `kernel.lift_mono`: the lift of a monomorphism `k : W ⟶ X` such that `k ≫ f = 0`
is still a monomorphism
* `kernel.is_limit_cone_zero_cone`: if our category has a zero object, then the map from the zero
obect is a kernel map of any monomorphism
* `kernel.ι_of_zero`: `kernel.ι (0 : X ⟶ Y)` is an isomorphism
and the corresponding dual statements.
## Future work
* TODO: connect this with existing working in the group theory and ring theory libraries.
## Implementation notes
As with the other special shapes in the limits library, all the definitions here are given as
`abbreviation`s of the general statements for limits, so all the `simp` lemmas and theorems about
general limits can be used.
## References
* [F. Borceux, *Handbook of Categorical Algebra 2*][borceux-vol2]
-/
noncomputable theory
universes v u u'
open category_theory
open category_theory.limits.walking_parallel_pair
namespace category_theory.limits
variables {C : Type u} [category.{v} C]
variables [has_zero_morphisms C]
/-- A morphism `f` has a kernel if the functor `parallel_pair f 0` has a limit. -/
abbreviation has_kernel {X Y : C} (f : X ⟶ Y) : Prop := has_limit (parallel_pair f 0)
/-- A morphism `f` has a cokernel if the functor `parallel_pair f 0` has a colimit. -/
abbreviation has_cokernel {X Y : C} (f : X ⟶ Y) : Prop := has_colimit (parallel_pair f 0)
variables {X Y : C} (f : X ⟶ Y)
section
/-- A kernel fork is just a fork where the second morphism is a zero morphism. -/
abbreviation kernel_fork := fork f 0
variables {f}
@[simp, reassoc] lemma kernel_fork.condition (s : kernel_fork f) : fork.ι s ≫ f = 0 :=
by erw [fork.condition, has_zero_morphisms.comp_zero]
@[simp] lemma kernel_fork.app_one (s : kernel_fork f) : s.π.app one = 0 :=
by rw [←fork.app_zero_left, kernel_fork.condition]
/-- A morphism `ι` satisfying `ι ≫ f = 0` determines a kernel fork over `f`. -/
abbreviation kernel_fork.of_ι {Z : C} (ι : Z ⟶ X) (w : ι ≫ f = 0) : kernel_fork f :=
fork.of_ι ι $ by rw [w, has_zero_morphisms.comp_zero]
@[simp] lemma kernel_fork.ι_of_ι {X Y P : C} (f : X ⟶ Y) (ι : P ⟶ X) (w : ι ≫ f = 0) :
fork.ι (kernel_fork.of_ι ι w) = ι := rfl
section
local attribute [tidy] tactic.case_bash
/-- Every kernel fork `s` is isomorphic (actually, equal) to `fork.of_ι (fork.ι s) _`. -/
def iso_of_ι (s : fork f 0) : s ≅ fork.of_ι (fork.ι s) (fork.condition s) :=
cones.ext (iso.refl _) $ by tidy
/-- If `ι = ι'`, then `fork.of_ι ι _` and `fork.of_ι ι' _` are isomorphic. -/
def of_ι_congr {P : C} {ι ι' : P ⟶ X} {w : ι ≫ f = 0} (h : ι = ι') :
kernel_fork.of_ι ι w ≅ kernel_fork.of_ι ι' (by rw [←h, w]) :=
cones.ext (iso.refl _) $ by tidy
/-- If `F` is an equivalence, then applying `F` to a diagram indexing a (co)kernel of `f` yields
the diagram indexing the (co)kernel of `F.map f`. -/
def comp_nat_iso {D : Type u'} [category.{v} D] [has_zero_morphisms D] (F : C ⥤ D)
[is_equivalence F] : parallel_pair f 0 ⋙ F ≅ parallel_pair (F.map f) 0 :=
nat_iso.of_components (λ j, match j with
| zero := iso.refl _
| one := iso.refl _
end) $ by tidy
end
/-- If `s` is a limit kernel fork and `k : W ⟶ X` satisfies ``k ≫ f = 0`, then there is some
`l : W ⟶ s.X` such that `l ≫ fork.ι s = k`. -/
def kernel_fork.is_limit.lift' {s : kernel_fork f} (hs : is_limit s) {W : C} (k : W ⟶ X)
(h : k ≫ f = 0) : {l : W ⟶ s.X // l ≫ fork.ι s = k} :=
⟨hs.lift $ kernel_fork.of_ι _ h, hs.fac _ _⟩
/-- This is a slightly more convenient method to verify that a kernel fork is a limit cone. It
only asks for a proof of facts that carry any mathematical content -/
def is_limit_aux (t : kernel_fork f)
(lift : Π (s : kernel_fork f), s.X ⟶ t.X)
(fac : ∀ (s : kernel_fork f), lift s ≫ t.ι = s.ι)
(uniq : ∀ (s : kernel_fork f) (m : s.X ⟶ t.X) (w : m ≫ t.ι = s.ι), m = lift s) :
is_limit t :=
{ lift := lift,
fac' := λ s j, by { cases j, { exact fac s, }, { simp, }, },
uniq' := λ s m w, uniq s m (w limits.walking_parallel_pair.zero), }
/--
This is a more convenient formulation to show that a `kernel_fork` constructed using
`kernel_fork.of_ι` is a limit cone.
-/
def is_limit.of_ι {W : C} (g : W ⟶ X) (eq : g ≫ f = 0)
(lift : Π {W' : C} (g' : W' ⟶ X) (eq' : g' ≫ f = 0), W' ⟶ W)
(fac : ∀ {W' : C} (g' : W' ⟶ X) (eq' : g' ≫ f = 0), lift g' eq' ≫ g = g')
(uniq :
∀ {W' : C} (g' : W' ⟶ X) (eq' : g' ≫ f = 0) (m : W' ⟶ W) (w : m ≫ g = g'), m = lift g' eq') :
is_limit (kernel_fork.of_ι g eq) :=
is_limit_aux _ (λ s, lift s.ι s.condition) (λ s, fac s.ι s.condition) (λ s, uniq s.ι s.condition)
end
section
variables [has_kernel f]
/-- The kernel of a morphism, expressed as the equalizer with the 0 morphism. -/
abbreviation kernel : C := equalizer f 0
/-- The map from `kernel f` into the source of `f`. -/
abbreviation kernel.ι : kernel f ⟶ X := equalizer.ι f 0
@[simp] lemma equalizer_as_kernel : equalizer.ι f 0 = kernel.ι f := rfl
@[simp, reassoc] lemma kernel.condition : kernel.ι f ≫ f = 0 :=
kernel_fork.condition _
/-- Given any morphism `k : W ⟶ X` satisfying `k ≫ f = 0`, `k` factors through `kernel.ι f`
via `kernel.lift : W ⟶ kernel f`. -/
abbreviation kernel.lift {W : C} (k : W ⟶ X) (h : k ≫ f = 0) : W ⟶ kernel f :=
limit.lift (parallel_pair f 0) (kernel_fork.of_ι k h)
@[simp, reassoc]
lemma kernel.lift_ι {W : C} (k : W ⟶ X) (h : k ≫ f = 0) : kernel.lift f k h ≫ kernel.ι f = k :=
limit.lift_π _ _
@[simp]
lemma kernel.lift_zero {W : C} {h} : kernel.lift f (0 : W ⟶ X) h = 0 :=
by { ext, simp, }
instance kernel.lift_mono {W : C} (k : W ⟶ X) (h : k ≫ f = 0) [mono k] : mono (kernel.lift f k h) :=
⟨λ Z g g' w,
begin
replace w := w =≫ kernel.ι f,
simp only [category.assoc, kernel.lift_ι] at w,
exact (cancel_mono k).1 w,
end⟩
/-- Any morphism `k : W ⟶ X` satisfying `k ≫ f = 0` induces a morphism `l : W ⟶ kernel f` such that
`l ≫ kernel.ι f = k`. -/
def kernel.lift' {W : C} (k : W ⟶ X) (h : k ≫ f = 0) : {l : W ⟶ kernel f // l ≫ kernel.ι f = k} :=
⟨kernel.lift f k h, kernel.lift_ι _ _ _⟩
/-- Every kernel of the zero morphism is an isomorphism -/
instance kernel.ι_zero_is_iso : is_iso (kernel.ι (0 : X ⟶ Y)) :=
equalizer.ι_of_self _
lemma eq_zero_of_epi_kernel [epi (kernel.ι f)] : f = 0 :=
(cancel_epi (kernel.ι f)).1 (by simp)
/-- The kernel of a zero morphism is isomorphic to the source. -/
def kernel_zero_iso_source : kernel (0 : X ⟶ Y) ≅ X :=
equalizer.iso_source_of_self 0
@[simp] lemma kernel_zero_iso_source_hom :
kernel_zero_iso_source.hom = kernel.ι (0 : X ⟶ Y) := rfl
@[simp] lemma kernel_zero_iso_source_inv :
kernel_zero_iso_source.inv = kernel.lift (0 : X ⟶ Y) (𝟙 X) (by simp) :=
by { ext, simp [kernel_zero_iso_source], }
/-- If two morphisms are known to be equal, then their kernels are isomorphic. -/
def kernel_iso_of_eq {f g : X ⟶ Y} [has_kernel f] [has_kernel g] (h : f = g) :
kernel f ≅ kernel g :=
has_limit.iso_of_nat_iso (by simp[h])
@[simp]
lemma kernel_iso_of_eq_refl {h : f = f} : kernel_iso_of_eq h = iso.refl (kernel f) :=
by { ext, simp [kernel_iso_of_eq], }
@[simp]
lemma kernel_iso_of_eq_trans {f g h : X ⟶ Y} [has_kernel f] [has_kernel g] [has_kernel h]
(w₁ : f = g) (w₂ : g = h) :
kernel_iso_of_eq w₁ ≪≫ kernel_iso_of_eq w₂ = kernel_iso_of_eq (w₁.trans w₂) :=
by { unfreezingI { induction w₁, induction w₂, }, ext, simp [kernel_iso_of_eq], }
variables {f}
lemma kernel_not_epi_of_nonzero (w : f ≠ 0) : ¬epi (kernel.ι f) :=
λ I, by exactI w (eq_zero_of_epi_kernel f)
lemma kernel_not_iso_of_nonzero (w : f ≠ 0) : (is_iso (kernel.ι f)) → false :=
λ I, kernel_not_epi_of_nonzero w $ by { resetI, apply_instance }
-- TODO the remainder of this section has obvious generalizations to `has_equalizer f g`.
instance has_kernel_comp_mono {X Y Z : C} (f : X ⟶ Y) [has_kernel f] (g : Y ⟶ Z) [mono g] :
has_kernel (f ≫ g) :=
{ exists_limit :=
⟨{ cone := kernel_fork.of_ι (kernel.ι f) (by simp),
is_limit := is_limit_aux _ (λ s, kernel.lift _ s.ι ((cancel_mono g).mp (by simp)))
(by tidy) (by tidy) }⟩ }
/--
When `g` is a monomorphism, the kernel of `f ≫ g` is isomorphic to the kernel of `f`.
-/
@[simps]
def kernel_comp_mono {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z) [has_kernel f] [mono g] :
kernel (f ≫ g) ≅ kernel f :=
{ hom := kernel.lift _ (kernel.ι _) (by { rw [←cancel_mono g], simp, }),
inv := kernel.lift _ (kernel.ι _) (by simp), }
instance has_kernel_iso_comp {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z) [is_iso f] [has_kernel g] :
has_kernel (f ≫ g) :=
{ exists_limit :=
⟨{ cone := kernel_fork.of_ι (kernel.ι g ≫ inv f) (by simp),
is_limit := is_limit_aux _ (λ s, kernel.lift _ (s.ι ≫ f) (by tidy)) (by tidy)
(λ s m w, by { simp_rw [←w], ext, simp, }), }⟩ }
/--
When `f` is an isomorphism, the kernel of `f ≫ g` is isomorphic to the kernel of `g`.
-/
@[simps]
def kernel_is_iso_comp {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z) [is_iso f] [has_kernel g] :
kernel (f ≫ g) ≅ kernel g :=
{ hom := kernel.lift _ (kernel.ι _ ≫ f) (by simp),
inv := kernel.lift _ (kernel.ι _ ≫ inv f) (by simp), }
end
section has_zero_object
variables [has_zero_object C]
local attribute [instance] has_zero_object.has_zero
/-- The morphism from the zero object determines a cone on a kernel diagram -/
def kernel.zero_cone : cone (parallel_pair f 0) :=
{ X := 0,
π := { app := λ j, 0 }}
/-- The map from the zero object is a kernel of a monomorphism -/
def kernel.is_limit_cone_zero_cone [mono f] : is_limit (kernel.zero_cone f) :=
fork.is_limit.mk _ (λ s, 0)
(λ s, by { erw zero_comp,
convert (zero_of_comp_mono f _).symm,
exact kernel_fork.condition _ })
(λ _ _ _, zero_of_to_zero _)
/-- The kernel of a monomorphism is isomorphic to the zero object -/
def kernel.of_mono [has_kernel f] [mono f] : kernel f ≅ 0 :=
functor.map_iso (cones.forget _) $ is_limit.unique_up_to_iso
(limit.is_limit (parallel_pair f 0)) (kernel.is_limit_cone_zero_cone f)
/-- The kernel morphism of a monomorphism is a zero morphism -/
lemma kernel.ι_of_mono [has_kernel f] [mono f] : kernel.ι f = 0 :=
zero_of_source_iso_zero _ (kernel.of_mono f)
end has_zero_object
section transport
/-- If `i` is an isomorphism such that `l ≫ i.hom = f`, then any kernel of `f` is a kernel of `l`.-/
def is_kernel.of_comp_iso {Z : C} (l : X ⟶ Z) (i : Z ≅ Y) (h : l ≫ i.hom = f)
{s : kernel_fork f} (hs : is_limit s) : is_limit (kernel_fork.of_ι (fork.ι s) $
show fork.ι s ≫ l = 0, by simp [←i.comp_inv_eq.2 h.symm]) :=
fork.is_limit.mk _
(λ s, hs.lift $ kernel_fork.of_ι (fork.ι s) $ by simp [←h])
(λ s, by simp)
(λ s m h, by { apply fork.is_limit.hom_ext hs, simpa using h walking_parallel_pair.zero })
/-- If `i` is an isomorphism such that `l ≫ i.hom = f`, then the kernel of `f` is a kernel of `l`.-/
def kernel.of_comp_iso [has_kernel f]
{Z : C} (l : X ⟶ Z) (i : Z ≅ Y) (h : l ≫ i.hom = f) :
is_limit (kernel_fork.of_ι (kernel.ι f) $
show kernel.ι f ≫ l = 0, by simp [←i.comp_inv_eq.2 h.symm]) :=
is_kernel.of_comp_iso f l i h $ limit.is_limit _
/-- If `s` is any limit kernel cone over `f` and if `i` is an isomorphism such that
`i.hom ≫ s.ι = l`, then `l` is a kernel of `f`. -/
def is_kernel.iso_kernel {Z : C} (l : Z ⟶ X) {s : kernel_fork f} (hs : is_limit s)
(i : Z ≅ s.X) (h : i.hom ≫ fork.ι s = l) : is_limit (kernel_fork.of_ι l $
show l ≫ f = 0, by simp [←h]) :=
is_limit.of_iso_limit hs $ cones.ext i.symm $ λ j,
by { cases j, { exact (iso.eq_inv_comp i).2 h }, { simp } }
/-- If `i` is an isomorphism such that `i.hom ≫ kernel.ι f = l`, then `l` is a kernel of `f`. -/
def kernel.iso_kernel [has_kernel f]
{Z : C} (l : Z ⟶ X) (i : Z ≅ kernel f) (h : i.hom ≫ kernel.ι f = l) :
is_limit (kernel_fork.of_ι l $ by simp [←h]) :=
is_kernel.iso_kernel f l (limit.is_limit _) i h
end transport
section
variables (X Y)
/-- The kernel morphism of a zero morphism is an isomorphism -/
lemma kernel.ι_of_zero : is_iso (kernel.ι (0 : X ⟶ Y)) :=
equalizer.ι_of_self _
end
section
/-- A cokernel cofork is just a cofork where the second morphism is a zero morphism. -/
abbreviation cokernel_cofork := cofork f 0
variables {f}
@[simp, reassoc] lemma cokernel_cofork.condition (s : cokernel_cofork f) : f ≫ cofork.π s = 0 :=
by rw [cofork.condition, zero_comp]
@[simp] lemma cokernel_cofork.app_zero (s : cokernel_cofork f) : s.ι.app zero = 0 :=
by rw [←cofork.left_app_one, cokernel_cofork.condition]
/-- A morphism `π` satisfying `f ≫ π = 0` determines a cokernel cofork on `f`. -/
abbreviation cokernel_cofork.of_π {Z : C} (π : Y ⟶ Z) (w : f ≫ π = 0) : cokernel_cofork f :=
cofork.of_π π $ by rw [w, zero_comp]
@[simp] lemma cokernel_cofork.π_of_π {X Y P : C} (f : X ⟶ Y) (π : Y ⟶ P) (w : f ≫ π = 0) :
cofork.π (cokernel_cofork.of_π π w) = π := rfl
/-- Every cokernel cofork `s` is isomorphic (actually, equal) to `cofork.of_π (cofork.π s) _`. -/
def iso_of_π (s : cofork f 0) : s ≅ cofork.of_π (cofork.π s) (cofork.condition s) :=
cocones.ext (iso.refl _) $ λ j, by cases j; tidy
/-- If `π = π'`, then `cokernel_cofork.of_π π _` and `cokernel_cofork.of_π π' _` are isomorphic. -/
def of_π_congr {P : C} {π π' : Y ⟶ P} {w : f ≫ π = 0} (h : π = π') :
cokernel_cofork.of_π π w ≅ cokernel_cofork.of_π π' (by rw [←h, w]) :=
cocones.ext (iso.refl _) $ λ j, by cases j; tidy
/-- If `s` is a colimit cokernel cofork, then every `k : Y ⟶ W` satisfying `f ≫ k = 0` induces
`l : s.X ⟶ W` such that `cofork.π s ≫ l = k`. -/
def cokernel_cofork.is_colimit.desc' {s : cokernel_cofork f} (hs : is_colimit s) {W : C} (k : Y ⟶ W)
(h : f ≫ k = 0) : {l : s.X ⟶ W // cofork.π s ≫ l = k} :=
⟨hs.desc $ cokernel_cofork.of_π _ h, hs.fac _ _⟩
/--
This is a slightly more convenient method to verify that a cokernel cofork is a colimit cocone.
It only asks for a proof of facts that carry any mathematical content -/
def is_colimit_aux (t : cokernel_cofork f)
(desc : Π (s : cokernel_cofork f), t.X ⟶ s.X)
(fac : ∀ (s : cokernel_cofork f), t.π ≫ desc s = s.π)
(uniq : ∀ (s : cokernel_cofork f) (m : t.X ⟶ s.X) (w : t.π ≫ m = s.π), m = desc s) :
is_colimit t :=
{ desc := desc,
fac' := λ s j, by { cases j, { simp, }, { exact fac s, }, },
uniq' := λ s m w, uniq s m (w limits.walking_parallel_pair.one), }
/--
This is a more convenient formulation to show that a `cokernel_cofork` constructed using
`cokernel_cofork.of_π` is a limit cone.
-/
def is_colimit.of_π {Z : C} (g : Y ⟶ Z) (eq : f ≫ g = 0)
(desc : Π {Z' : C} (g' : Y ⟶ Z') (eq' : f ≫ g' = 0), Z ⟶ Z')
(fac : ∀ {Z' : C} (g' : Y ⟶ Z') (eq' : f ≫ g' = 0), g ≫ desc g' eq' = g')
(uniq :
∀ {Z' : C} (g' : Y ⟶ Z') (eq' : f ≫ g' = 0) (m : Z ⟶ Z') (w : g ≫ m = g'), m = desc g' eq') :
is_colimit (cokernel_cofork.of_π g eq) :=
is_colimit_aux _ (λ s, desc s.π s.condition) (λ s, fac s.π s.condition) (λ s, uniq s.π s.condition)
end
section
variables [has_cokernel f]
/-- The cokernel of a morphism, expressed as the coequalizer with the 0 morphism. -/
abbreviation cokernel : C := coequalizer f 0
/-- The map from the target of `f` to `cokernel f`. -/
abbreviation cokernel.π : Y ⟶ cokernel f := coequalizer.π f 0
@[simp] lemma coequalizer_as_cokernel : coequalizer.π f 0 = cokernel.π f := rfl
@[simp, reassoc] lemma cokernel.condition : f ≫ cokernel.π f = 0 :=
cokernel_cofork.condition _
/-- Given any morphism `k : Y ⟶ W` such that `f ≫ k = 0`, `k` factors through `cokernel.π f`
via `cokernel.desc : cokernel f ⟶ W`. -/
abbreviation cokernel.desc {W : C} (k : Y ⟶ W) (h : f ≫ k = 0) : cokernel f ⟶ W :=
colimit.desc (parallel_pair f 0) (cokernel_cofork.of_π k h)
@[simp, reassoc]
lemma cokernel.π_desc {W : C} (k : Y ⟶ W) (h : f ≫ k = 0) :
cokernel.π f ≫ cokernel.desc f k h = k :=
colimit.ι_desc _ _
@[simp]
lemma cokernel.desc_zero {W : C} {h} : cokernel.desc f (0 : Y ⟶ W) h = 0 :=
by { ext, simp, }
instance cokernel.desc_epi
{W : C} (k : Y ⟶ W) (h : f ≫ k = 0) [epi k] : epi (cokernel.desc f k h) :=
⟨λ Z g g' w,
begin
replace w := cokernel.π f ≫= w,
simp only [cokernel.π_desc_assoc] at w,
exact (cancel_epi k).1 w,
end⟩
/-- Any morphism `k : Y ⟶ W` satisfying `f ≫ k = 0` induces `l : cokernel f ⟶ W` such that
`cokernel.π f ≫ l = k`. -/
def cokernel.desc' {W : C} (k : Y ⟶ W) (h : f ≫ k = 0) :
{l : cokernel f ⟶ W // cokernel.π f ≫ l = k} :=
⟨cokernel.desc f k h, cokernel.π_desc _ _ _⟩
/-- The cokernel of the zero morphism is an isomorphism -/
instance cokernel.π_zero_is_iso :
is_iso (cokernel.π (0 : X ⟶ Y)) :=
coequalizer.π_of_self _
lemma eq_zero_of_mono_cokernel [mono (cokernel.π f)] : f = 0 :=
(cancel_mono (cokernel.π f)).1 (by simp)
/-- The cokernel of a zero morphism is isomorphic to the target. -/
def cokernel_zero_iso_target : cokernel (0 : X ⟶ Y) ≅ Y :=
coequalizer.iso_target_of_self 0
@[simp] lemma cokernel_zero_iso_target_hom :
cokernel_zero_iso_target.hom = cokernel.desc (0 : X ⟶ Y) (𝟙 Y) (by simp) :=
by { ext, simp [cokernel_zero_iso_target], }
@[simp] lemma cokernel_zero_iso_target_inv :
cokernel_zero_iso_target.inv = cokernel.π (0 : X ⟶ Y) := rfl
/-- If two morphisms are known to be equal, then their cokernels are isomorphic. -/
def cokernel_iso_of_eq {f g : X ⟶ Y} [has_cokernel f] [has_cokernel g] (h : f = g) :
cokernel f ≅ cokernel g :=
has_colimit.iso_of_nat_iso (by simp[h])
@[simp]
lemma cokernel_iso_of_eq_refl {h : f = f} : cokernel_iso_of_eq h = iso.refl (cokernel f) :=
by { ext, simp [cokernel_iso_of_eq], }
@[simp]
lemma cokernel_iso_of_eq_trans {f g h : X ⟶ Y} [has_cokernel f] [has_cokernel g] [has_cokernel h]
(w₁ : f = g) (w₂ : g = h) :
cokernel_iso_of_eq w₁ ≪≫ cokernel_iso_of_eq w₂ = cokernel_iso_of_eq (w₁.trans w₂) :=
by { unfreezingI { induction w₁, induction w₂, }, ext, simp [cokernel_iso_of_eq], }
variables {f}
lemma cokernel_not_mono_of_nonzero (w : f ≠ 0) : ¬mono (cokernel.π f) :=
λ I, by exactI w (eq_zero_of_mono_cokernel f)
lemma cokernel_not_iso_of_nonzero (w : f ≠ 0) : (is_iso (cokernel.π f)) → false :=
λ I, cokernel_not_mono_of_nonzero w $ by { resetI, apply_instance }
-- TODO the remainder of this section has obvious generalizations to `has_coequalizer f g`.
instance has_cokernel_comp_iso {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z) [has_cokernel f] [is_iso g] :
has_cokernel (f ≫ g) :=
{ exists_colimit :=
⟨{ cocone := cokernel_cofork.of_π (inv g ≫ cokernel.π f) (by simp),
is_colimit := is_colimit_aux _ (λ s, cokernel.desc _ (g ≫ s.π)
(by { rw [←category.assoc, cokernel_cofork.condition], }))
(by tidy)
(λ s m w, by { simp_rw [←w], ext, simp, }), }⟩ }
/--
When `g` is an isomorphism, the cokernel of `f ≫ g` is isomorphic to the cokernel of `f`.
-/
@[simps]
def cokernel_comp_is_iso {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z) [has_cokernel f] [is_iso g] :
cokernel (f ≫ g) ≅ cokernel f :=
{ hom := cokernel.desc _ (inv g ≫ cokernel.π f) (by simp),
inv := cokernel.desc _ (g ≫ cokernel.π (f ≫ g)) (by rw [←category.assoc, cokernel.condition]), }
instance has_cokernel_epi_comp {X Y Z : C} (f : X ⟶ Y) [epi f] (g : Y ⟶ Z) [has_cokernel g] :
has_cokernel (f ≫ g) :=
{ exists_colimit :=
⟨{ cocone := cokernel_cofork.of_π (cokernel.π g) (by simp),
is_colimit := is_colimit_aux _
(λ s, cokernel.desc _ s.π ((cancel_epi f).mp (by { rw ← category.assoc, simp })))
(by tidy) (by tidy) }⟩ }
/--
When `f` is an epimorphism, the cokernel of `f ≫ g` is isomorphic to the cokernel of `g`.
-/
@[simps]
def cokernel_epi_comp {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z)
[epi f] [has_cokernel g] :
cokernel (f ≫ g) ≅ cokernel g :=
{ hom := cokernel.desc _ (cokernel.π g) (by simp),
inv := cokernel.desc _ (cokernel.π (f ≫ g)) (by { rw [←cancel_epi f, ←category.assoc], simp, }), }
end
section has_zero_object
variables [has_zero_object C]
local attribute [instance] has_zero_object.has_zero
/-- The morphism to the zero object determines a cocone on a cokernel diagram -/
def cokernel.zero_cocone : cocone (parallel_pair f 0) :=
{ X := 0,
ι := { app := λ j, 0 } }
/-- The morphism to the zero object is a cokernel of an epimorphism -/
def cokernel.is_colimit_cocone_zero_cocone [epi f] : is_colimit (cokernel.zero_cocone f) :=
cofork.is_colimit.mk _ (λ s, 0)
(λ s, by { erw zero_comp,
convert (zero_of_epi_comp f _).symm,
exact cokernel_cofork.condition _ })
(λ _ _ _, zero_of_from_zero _)
/-- The cokernel of an epimorphism is isomorphic to the zero object -/
def cokernel.of_epi [has_cokernel f] [epi f] : cokernel f ≅ 0 :=
functor.map_iso (cocones.forget _) $ is_colimit.unique_up_to_iso
(colimit.is_colimit (parallel_pair f 0)) (cokernel.is_colimit_cocone_zero_cocone f)
/-- The cokernel morphism of an epimorphism is a zero morphism -/
lemma cokernel.π_of_epi [has_cokernel f] [epi f] : cokernel.π f = 0 :=
zero_of_target_iso_zero _ (cokernel.of_epi f)
end has_zero_object
section has_image
/--
The cokernel of the image inclusion of a morphism `f` is isomorphic to the cokernel of `f`.
(This result requires that the factorisation through the image is an epimorphism.
This holds in any category with equalizers.)
-/
@[simps]
def cokernel_image_ι {X Y : C} (f : X ⟶ Y)
[has_image f] [has_cokernel (image.ι f)] [has_cokernel f] [epi (factor_thru_image f)] :
cokernel (image.ι f) ≅ cokernel f :=
{ hom := cokernel.desc _ (cokernel.π f)
begin
have w := cokernel.condition f,
conv at w { to_lhs, congr, rw ←image.fac f, },
rw [←has_zero_morphisms.comp_zero (limits.factor_thru_image f), category.assoc, cancel_epi]
at w,
exact w,
end,
inv := cokernel.desc _ (cokernel.π _)
begin
conv { to_lhs, congr, rw ←image.fac f, },
rw [category.assoc, cokernel.condition, has_zero_morphisms.comp_zero],
end, }
end has_image
section
variables (X Y)
/-- The cokernel of a zero morphism is an isomorphism -/
lemma cokernel.π_of_zero :
is_iso (cokernel.π (0 : X ⟶ Y)) :=
coequalizer.π_of_self _
end
section has_zero_object
variables [has_zero_object C]
local attribute [instance] has_zero_object.has_zero
/-- The kernel of the cokernel of an epimorphism is an isomorphism -/
instance kernel.of_cokernel_of_epi [has_cokernel f]
[has_kernel (cokernel.π f)] [epi f] : is_iso (kernel.ι (cokernel.π f)) :=
equalizer.ι_of_eq $ cokernel.π_of_epi f
/-- The cokernel of the kernel of a monomorphism is an isomorphism -/
instance cokernel.of_kernel_of_mono [has_kernel f]
[has_cokernel (kernel.ι f)] [mono f] : is_iso (cokernel.π (kernel.ι f)) :=
coequalizer.π_of_eq $ kernel.ι_of_mono f
end has_zero_object
section transport
/-- If `i` is an isomorphism such that `i.hom ≫ l = f`, then any cokernel of `f` is a cokernel of
`l`. -/
def is_cokernel.of_iso_comp {Z : C} (l : Z ⟶ Y) (i : X ≅ Z) (h : i.hom ≫ l = f)
{s : cokernel_cofork f} (hs : is_colimit s) : is_colimit (cokernel_cofork.of_π (cofork.π s) $
show l ≫ cofork.π s = 0, by simp [i.eq_inv_comp.2 h]) :=
cofork.is_colimit.mk _
(λ s, hs.desc $ cokernel_cofork.of_π (cofork.π s) $ by simp [←h])
(λ s, by simp)
(λ s m h, by { apply cofork.is_colimit.hom_ext hs, simpa using h walking_parallel_pair.one })
/-- If `i` is an isomorphism such that `i.hom ≫ l = f`, then the cokernel of `f` is a cokernel of
`l`. -/
def cokernel.of_iso_comp [has_cokernel f]
{Z : C} (l : Z ⟶ Y) (i : X ≅ Z) (h : i.hom ≫ l = f) :
is_colimit (cokernel_cofork.of_π (cokernel.π f) $
show l ≫ cokernel.π f = 0, by simp [i.eq_inv_comp.2 h]) :=
is_cokernel.of_iso_comp f l i h $ colimit.is_colimit _
/-- If `s` is any colimit cokernel cocone over `f` and `i` is an isomorphism such that
`s.π ≫ i.hom = l`, then `l` is a cokernel of `f`. -/
def is_cokernel.cokernel_iso {Z : C} (l : Y ⟶ Z) {s : cokernel_cofork f} (hs : is_colimit s)
(i : s.X ≅ Z) (h : cofork.π s ≫ i.hom = l) : is_colimit (cokernel_cofork.of_π l $
show f ≫ l = 0, by simp [←h]) :=
is_colimit.of_iso_colimit hs $ cocones.ext i $ λ j, by { cases j, { simp }, { exact h } }
/-- If `i` is an isomorphism such that `cokernel.π f ≫ i.hom = l`, then `l` is a cokernel of `f`. -/
def cokernel.cokernel_iso [has_cokernel f]
{Z : C} (l : Y ⟶ Z) (i : cokernel f ≅ Z) (h : cokernel.π f ≫ i.hom = l) :
is_colimit (cokernel_cofork.of_π l $ by simp [←h]) :=
is_cokernel.cokernel_iso f l (colimit.is_colimit _) i h
end transport
end category_theory.limits
namespace category_theory.limits
variables (C : Type u) [category.{v} C]
variables [has_zero_morphisms C]
/-- `has_kernels` represents the existence of kernels for every morphism. -/
class has_kernels : Prop :=
(has_limit : Π {X Y : C} (f : X ⟶ Y), has_kernel f . tactic.apply_instance)
/-- `has_cokernels` represents the existence of cokernels for every morphism. -/
class has_cokernels : Prop :=
(has_colimit : Π {X Y : C} (f : X ⟶ Y), has_cokernel f . tactic.apply_instance)
attribute [instance, priority 100] has_kernels.has_limit has_cokernels.has_colimit
@[priority 100]
instance has_kernels_of_has_equalizers [has_equalizers C] : has_kernels C :=
{}
@[priority 100]
instance has_cokernels_of_has_coequalizers [has_coequalizers C] : has_cokernels C :=
{}
end category_theory.limits
|
8a6d8a78d51f90f3320e842bf059767c019f96af | 4d2583807a5ac6caaffd3d7a5f646d61ca85d532 | /src/topology/path_connected.lean | e20611c405996ff6ac60136175f02d1b918f7d78 | [
"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 | 37,416 | lean | /-
Copyright (c) 2020 Patrick Massot. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Patrick Massot
-/
import topology.unit_interval
import topology.algebra.ordered.proj_Icc
import topology.continuous_function.basic
/-!
# Path connectedness
## Main definitions
In the file the unit interval `[0, 1]` in `ℝ` is denoted by `I`, and `X` is a topological space.
* `path (x y : X)` is the type of paths from `x` to `y`, i.e., continuous maps from `I` to `X`
mapping `0` to `x` and `1` to `y`.
* `path.map` is the image of a path under a continuous map.
* `joined (x y : X)` means there is a path between `x` and `y`.
* `joined.some_path (h : joined x y)` selects some path between two points `x` and `y`.
* `path_component (x : X)` is the set of points joined to `x`.
* `path_connected_space X` is a predicate class asserting that `X` is non-empty and every two
points of `X` are joined.
Then there are corresponding relative notions for `F : set X`.
* `joined_in F (x y : X)` means there is a path `γ` joining `x` to `y` with values in `F`.
* `joined_in.some_path (h : joined_in F x y)` selects a path from `x` to `y` inside `F`.
* `path_component_in F (x : X)` is the set of points joined to `x` in `F`.
* `is_path_connected F` asserts that `F` is non-empty and every two
points of `F` are joined in `F`.
* `loc_path_connected_space X` is a predicate class asserting that `X` is locally path-connected:
each point has a basis of path-connected neighborhoods (we do *not* ask these to be open).
## Main theorems
* `joined` and `joined_in F` are transitive relations.
One can link the absolute and relative version in two directions, using `(univ : set X)` or the
subtype `↥F`.
* `path_connected_space_iff_univ : path_connected_space X ↔ is_path_connected (univ : set X)`
* `is_path_connected_iff_path_connected_space : is_path_connected F ↔ path_connected_space ↥F`
For locally path connected spaces, we have
* `path_connected_space_iff_connected_space : path_connected_space X ↔ connected_space X`
* `is_connected_iff_is_path_connected (U_op : is_open U) : is_path_connected U ↔ is_connected U`
## Implementation notes
By default, all paths have `I` as their source and `X` as their target, but there is an
operation `set.Icc_extend` that will extend any continuous map `γ : I → X` into a continuous map
`Icc_extend zero_le_one γ : ℝ → X` that is constant before `0` and after `1`.
This is used to define `path.extend` that turns `γ : path x y` into a continuous map
`γ.extend : ℝ → X` whose restriction to `I` is the original `γ`, and is equal to `x`
on `(-∞, 0]` and to `y` on `[1, +∞)`.
-/
noncomputable theory
open_locale classical topological_space filter unit_interval
open filter set function unit_interval
variables {X Y : Type*} [topological_space X] [topological_space Y] {x y z : X} {ι : Type*}
/-! ### Paths -/
/-- Continuous path connecting two points `x` and `y` in a topological space -/
@[nolint has_inhabited_instance]
structure path (x y : X) extends C(I, X) :=
(source' : to_fun 0 = x)
(target' : to_fun 1 = y)
instance : has_coe_to_fun (path x y) (λ _, I → X) := ⟨λ p, p.to_fun⟩
@[ext] protected lemma path.ext : ∀ {γ₁ γ₂ : path x y}, (γ₁ : I → X) = γ₂ → γ₁ = γ₂
| ⟨⟨x, h11⟩, h12, h13⟩ ⟨⟨.(x), h21⟩, h22, h23⟩ rfl := rfl
namespace path
@[simp] lemma coe_mk (f : I → X) (h₁ h₂ h₃) : ⇑(mk ⟨f, h₁⟩ h₂ h₃ : path x y) = f := rfl
variable (γ : path x y)
@[continuity]
protected lemma continuous : continuous γ :=
γ.continuous_to_fun
@[simp] protected lemma source : γ 0 = x :=
γ.source'
@[simp] protected lemma target : γ 1 = y :=
γ.target'
/-- See Note [custom simps projection]. We need to specify this projection explicitly in this case,
because it is a composition of multiple projections. -/
def simps.apply : I → X := γ
initialize_simps_projections path (to_continuous_map_to_fun → simps.apply, -to_continuous_map)
@[simp] lemma coe_to_continuous_map : ⇑γ.to_continuous_map = γ := rfl
/-- Any function `φ : Π (a : α), path (x a) (y a)` can be seen as a function `α × I → X`. -/
instance has_uncurry_path {X α : Type*} [topological_space X] {x y : α → X} :
has_uncurry (Π (a : α), path (x a) (y a)) (α × I) X :=
⟨λ φ p, φ p.1 p.2⟩
/-- The constant path from a point to itself -/
@[refl, simps] def refl (x : X) : path x x :=
{ to_fun := λ t, x,
continuous_to_fun := continuous_const,
source' := rfl,
target' := rfl }
@[simp] lemma refl_range {a : X} : range (path.refl a) = {a} :=
by simp [path.refl, has_coe_to_fun.coe, coe_fn]
/-- The reverse of a path from `x` to `y`, as a path from `y` to `x` -/
@[symm, simps] def symm (γ : path x y) : path y x :=
{ to_fun := γ ∘ σ,
continuous_to_fun := by continuity,
source' := by simpa [-path.target] using γ.target,
target' := by simpa [-path.source] using γ.source }
@[simp] lemma symm_symm {γ : path x y} : γ.symm.symm = γ :=
by { ext, simp }
@[simp] lemma refl_symm {a : X} : (path.refl a).symm = path.refl a :=
by { ext, refl }
@[simp] lemma symm_range {a b : X} (γ : path a b) : range γ.symm = range γ :=
begin
ext x,
simp only [mem_range, path.symm, has_coe_to_fun.coe, coe_fn, unit_interval.symm, set_coe.exists,
comp_app, subtype.coe_mk, subtype.val_eq_coe],
split; rintros ⟨y, hy, hxy⟩; refine ⟨1-y, mem_iff_one_sub_mem.mp hy, _⟩; convert hxy,
simp
end
/-- A continuous map extending a path to `ℝ`, constant before `0` and after `1`. -/
def extend : ℝ → X := Icc_extend zero_le_one γ
/-- See Note [continuity lemma statement]. -/
lemma _root_.continuous.path_extend {γ : Y → path x y} {f : Y → ℝ} (hγ : continuous ↿γ)
(hf : continuous f) : continuous (λ t, (γ t).extend (f t)) :=
continuous.Icc_extend hγ hf
/-- A useful special case of `continuous.path_extend`. -/
@[continuity]
lemma continuous_extend : continuous γ.extend :=
γ.continuous.Icc_extend'
lemma _root_.filter.tendsto.path_extend {X Y : Type*} [topological_space X] [topological_space Y]
{l r : Y → X} {y : Y} {l₁ : filter ℝ} {l₂ : filter X} {γ : ∀ y, path (l y) (r y)}
(hγ : tendsto ↿γ (𝓝 y ×ᶠ l₁.map (proj_Icc 0 1 zero_le_one)) l₂) :
tendsto ↿(λ x, (γ x).extend) (𝓝 y ×ᶠ l₁) l₂ :=
filter.tendsto.Icc_extend _ hγ
lemma _root_.continuous_at.path_extend {g : Y → ℝ} {l r : Y → X} (γ : ∀ y, path (l y) (r y)) {y : Y}
(hγ : continuous_at ↿γ (y, proj_Icc 0 1 zero_le_one (g y)))
(hg : continuous_at g y) : continuous_at (λ i, (γ i).extend (g i)) y :=
hγ.Icc_extend (λ x, γ x) hg
@[simp] lemma extend_extends {X : Type*} [topological_space X] {a b : X}
(γ : path a b) {t : ℝ} (ht : t ∈ (Icc 0 1 : set ℝ)) : γ.extend t = γ ⟨t, ht⟩ :=
Icc_extend_of_mem _ γ ht
lemma extend_zero : γ.extend 0 = x :=
by simp
lemma extend_one : γ.extend 1 = y :=
by simp
@[simp] lemma extend_extends' {X : Type*} [topological_space X] {a b : X}
(γ : path a b) (t : (Icc 0 1 : set ℝ)) : γ.extend t = γ t :=
Icc_extend_coe _ γ t
@[simp] lemma extend_range {X : Type*} [topological_space X] {a b : X}
(γ : path a b) : range γ.extend = range γ :=
Icc_extend_range _ γ
lemma extend_of_le_zero {X : Type*} [topological_space X] {a b : X}
(γ : path a b) {t : ℝ} (ht : t ≤ 0) : γ.extend t = a :=
(Icc_extend_of_le_left _ _ ht).trans γ.source
lemma extend_of_one_le {X : Type*} [topological_space X] {a b : X}
(γ : path a b) {t : ℝ} (ht : 1 ≤ t) : γ.extend t = b :=
(Icc_extend_of_right_le _ _ ht).trans γ.target
@[simp] lemma refl_extend {X : Type*} [topological_space X] {a : X} :
(path.refl a).extend = λ _, a := rfl
/-- The path obtained from a map defined on `ℝ` by restriction to the unit interval. -/
def of_line {f : ℝ → X} (hf : continuous_on f I) (h₀ : f 0 = x) (h₁ : f 1 = y) : path x y :=
{ to_fun := f ∘ coe,
continuous_to_fun := hf.comp_continuous continuous_subtype_coe subtype.prop,
source' := h₀,
target' := h₁ }
lemma of_line_mem {f : ℝ → X} (hf : continuous_on f I) (h₀ : f 0 = x) (h₁ : f 1 = y) :
∀ t, of_line hf h₀ h₁ t ∈ f '' I :=
λ ⟨t, t_in⟩, ⟨t, t_in, rfl⟩
local attribute [simp] Iic_def
/-- Concatenation of two paths from `x` to `y` and from `y` to `z`, putting the first
path on `[0, 1/2]` and the second one on `[1/2, 1]`. -/
@[trans] def trans (γ : path x y) (γ' : path y z) : path x z :=
{ to_fun := (λ t : ℝ, if t ≤ 1/2 then γ.extend (2*t) else γ'.extend (2*t-1)) ∘ coe,
continuous_to_fun :=
begin
refine (continuous.if_le _ _ continuous_id continuous_const (by norm_num)).comp
continuous_subtype_coe,
-- TODO: the following are provable by `continuity` but it is too slow
exacts [γ.continuous_extend.comp (continuous_const.mul continuous_id),
γ'.continuous_extend.comp ((continuous_const.mul continuous_id).sub continuous_const)]
end,
source' := by norm_num,
target' := by norm_num }
lemma trans_apply (γ : path x y) (γ' : path y z) (t : I) : (γ.trans γ') t =
if h : (t : ℝ) ≤ 1/2 then
γ ⟨2 * t, (mul_pos_mem_iff zero_lt_two).2 ⟨t.2.1, h⟩⟩
else
γ' ⟨2 * t - 1, two_mul_sub_one_mem_iff.2 ⟨(not_le.1 h).le, t.2.2⟩⟩ :=
show ite _ _ _ = _,
by split_ifs; rw extend_extends
@[simp] lemma trans_symm (γ : path x y) (γ' : path y z) :
(γ.trans γ').symm = γ'.symm.trans γ.symm :=
begin
ext t,
simp only [trans_apply, one_div, symm_apply, not_le, comp_app],
split_ifs with h h₁ h₂ h₃ h₄; rw [coe_symm_eq] at h,
{ have ht : (t : ℝ) = 1/2,
{ linarith [unit_interval.nonneg t, unit_interval.le_one t] },
norm_num [ht] },
{ refine congr_arg _ (subtype.ext _),
norm_num [sub_sub_assoc_swap, mul_sub] },
{ refine congr_arg _ (subtype.ext _),
have h : 2 - 2 * (t : ℝ) - 1 = 1 - 2 * t, by linarith,
norm_num [mul_sub, h] },
{ exfalso, linarith [unit_interval.nonneg t, unit_interval.le_one t] }
end
@[simp] lemma refl_trans_refl {X : Type*} [topological_space X] {a : X} :
(path.refl a).trans (path.refl a) = path.refl a :=
begin
ext,
simp only [path.trans, if_t_t, one_div, path.refl_extend],
refl
end
lemma trans_range {X : Type*} [topological_space X] {a b c : X}
(γ₁ : path a b) (γ₂ : path b c) : range (γ₁.trans γ₂) = range γ₁ ∪ range γ₂ :=
begin
rw path.trans,
apply eq_of_subset_of_subset,
{ rintros x ⟨⟨t, ht0, ht1⟩, hxt⟩,
by_cases h : t ≤ 1/2,
{ left,
use [2*t, ⟨by linarith, by linarith⟩],
rw ← γ₁.extend_extends,
unfold_coes at hxt,
simp only [h, comp_app, if_true] at hxt,
exact hxt },
{ right,
use [2*t-1, ⟨by linarith, by linarith⟩],
rw ← γ₂.extend_extends,
unfold_coes at hxt,
simp only [h, comp_app, if_false] at hxt,
exact hxt } },
{ rintros x (⟨⟨t, ht0, ht1⟩, hxt⟩ | ⟨⟨t, ht0, ht1⟩, hxt⟩),
{ use ⟨t/2, ⟨by linarith, by linarith⟩⟩,
unfold_coes,
have : t/2 ≤ 1/2 := by linarith,
simp only [this, comp_app, if_true],
ring_nf,
rwa γ₁.extend_extends },
{ by_cases h : t = 0,
{ use ⟨1/2, ⟨by linarith, by linarith⟩⟩,
unfold_coes,
simp only [h, comp_app, if_true, le_refl, mul_one_div_cancel (@two_ne_zero ℝ _ _)],
rw γ₁.extend_one,
rwa [← γ₂.extend_extends, h, γ₂.extend_zero] at hxt },
{ use ⟨(t+1)/2, ⟨by linarith, by linarith⟩⟩,
unfold_coes,
change t ≠ 0 at h,
have ht0 := lt_of_le_of_ne ht0 h.symm,
have : ¬ (t+1)/2 ≤ 1/2 := by {rw not_le, linarith},
simp only [comp_app, if_false, this],
ring_nf,
rwa γ₂.extend_extends } } }
end
/-- Image of a path from `x` to `y` by a continuous map -/
def map (γ : path x y) {Y : Type*} [topological_space Y]
{f : X → Y} (h : continuous f) : path (f x) (f y) :=
{ to_fun := f ∘ γ,
continuous_to_fun := by continuity,
source' := by simp,
target' := by simp }
@[simp] lemma map_coe (γ : path x y) {Y : Type*} [topological_space Y]
{f : X → Y} (h : continuous f) :
(γ.map h : I → Y) = f ∘ γ :=
by { ext t, refl }
/-- Casting a path from `x` to `y` to a path from `x'` to `y'` when `x' = x` and `y' = y` -/
def cast (γ : path x y) {x' y'} (hx : x' = x) (hy : y' = y) : path x' y' :=
{ to_fun := γ,
continuous_to_fun := γ.continuous,
source' := by simp [hx],
target' := by simp [hy] }
@[simp] lemma symm_cast {X : Type*} [topological_space X] {a₁ a₂ b₁ b₂ : X}
(γ : path a₂ b₂) (ha : a₁ = a₂) (hb : b₁ = b₂) :
(γ.cast ha hb).symm = (γ.symm).cast hb ha := rfl
@[simp] lemma trans_cast {X : Type*} [topological_space X] {a₁ a₂ b₁ b₂ c₁ c₂ : X}
(γ : path a₂ b₂) (γ' : path b₂ c₂) (ha : a₁ = a₂) (hb : b₁ = b₂) (hc : c₁ = c₂) :
(γ.cast ha hb).trans (γ'.cast hb hc) = (γ.trans γ').cast ha hc := rfl
@[simp] lemma cast_coe (γ : path x y) {x' y'} (hx : x' = x) (hy : y' = y) :
(γ.cast hx hy : I → X) = γ :=
rfl
@[continuity]
lemma symm_continuous_family {X ι : Type*} [topological_space X] [topological_space ι]
{a b : ι → X} (γ : Π (t : ι), path (a t) (b t)) (h : continuous ↿γ) :
continuous ↿(λ t, (γ t).symm) :=
h.comp (continuous_id.prod_map continuous_symm)
@[continuity]
lemma continuous_uncurry_extend_of_continuous_family {X ι : Type*} [topological_space X]
[topological_space ι] {a b : ι → X} (γ : Π (t : ι), path (a t) (b t)) (h : continuous ↿γ) :
continuous ↿(λ t, (γ t).extend) :=
h.comp (continuous_id.prod_map continuous_proj_Icc)
@[continuity]
lemma trans_continuous_family {X ι : Type*} [topological_space X] [topological_space ι]
{a b c : ι → X}
(γ₁ : Π (t : ι), path (a t) (b t)) (h₁ : continuous ↿γ₁)
(γ₂ : Π (t : ι), path (b t) (c t)) (h₂ : continuous ↿γ₂) :
continuous ↿(λ t, (γ₁ t).trans (γ₂ t)) :=
begin
have h₁' := path.continuous_uncurry_extend_of_continuous_family γ₁ h₁,
have h₂' := path.continuous_uncurry_extend_of_continuous_family γ₂ h₂,
simp only [has_uncurry.uncurry, has_coe_to_fun.coe, coe_fn, path.trans, (∘)],
refine continuous.if_le _ _ (continuous_subtype_coe.comp continuous_snd) continuous_const _,
{ change continuous ((λ p : ι × ℝ, (γ₁ p.1).extend p.2) ∘ (prod.map id (λ x, 2*x : I → ℝ))),
exact h₁'.comp (continuous_id.prod_map $ continuous_const.mul continuous_subtype_coe) },
{ change continuous ((λ p : ι × ℝ, (γ₂ p.1).extend p.2) ∘ (prod.map id (λ x, 2*x - 1 : I → ℝ))),
exact h₂'.comp (continuous_id.prod_map $
(continuous_const.mul continuous_subtype_coe).sub continuous_const) },
{ rintros st hst,
simp [hst, mul_inv_cancel (@two_ne_zero ℝ _ _)] }
end
/-! #### Truncating a path -/
/-- `γ.truncate t₀ t₁` is the path which follows the path `γ` on the
time interval `[t₀, t₁]` and stays still otherwise. -/
def truncate {X : Type*} [topological_space X] {a b : X}
(γ : path a b) (t₀ t₁ : ℝ) : path (γ.extend $ min t₀ t₁) (γ.extend t₁) :=
{ to_fun := λ s, γ.extend (min (max s t₀) t₁),
continuous_to_fun := γ.continuous_extend.comp
((continuous_subtype_coe.max continuous_const).min continuous_const),
source' :=
begin
simp only [min_def, max_def],
norm_cast,
split_ifs with h₁ h₂ h₃ h₄,
{ simp [γ.extend_of_le_zero h₁] },
{ congr, linarith },
{ have h₄ : t₁ ≤ 0 := le_of_lt (by simpa using h₂),
simp [γ.extend_of_le_zero h₄, γ.extend_of_le_zero h₁] },
all_goals { refl }
end,
target' :=
begin
simp only [min_def, max_def],
norm_cast,
split_ifs with h₁ h₂ h₃,
{ simp [γ.extend_of_one_le h₂] },
{ refl },
{ have h₄ : 1 ≤ t₀ := le_of_lt (by simpa using h₁),
simp [γ.extend_of_one_le h₄, γ.extend_of_one_le (h₄.trans h₃)] },
{ refl }
end }
/-- `γ.truncate_of_le t₀ t₁ h`, where `h : t₀ ≤ t₁` is `γ.truncate t₀ t₁`
casted as a path from `γ.extend t₀` to `γ.extend t₁`. -/
def truncate_of_le {X : Type*} [topological_space X] {a b : X}
(γ : path a b) {t₀ t₁ : ℝ} (h : t₀ ≤ t₁) : path (γ.extend t₀) (γ.extend t₁) :=
(γ.truncate t₀ t₁).cast (by rw min_eq_left h) rfl
lemma truncate_range {X : Type*} [topological_space X] {a b : X}
(γ : path a b) {t₀ t₁ : ℝ} : range (γ.truncate t₀ t₁) ⊆ range γ :=
begin
rw ← γ.extend_range,
simp only [range_subset_iff, set_coe.exists, set_coe.forall],
intros x hx,
simp only [has_coe_to_fun.coe, coe_fn, path.truncate, mem_range_self]
end
/-- For a path `γ`, `γ.truncate` gives a "continuous family of paths", by which we
mean the uncurried function which maps `(t₀, t₁, s)` to `γ.truncate t₀ t₁ s` is continuous. -/
@[continuity]
lemma truncate_continuous_family {X : Type*} [topological_space X] {a b : X}
(γ : path a b) : continuous (λ x, γ.truncate x.1 x.2.1 x.2.2 : ℝ × ℝ × I → X) :=
γ.continuous_extend.comp
(((continuous_subtype_coe.comp (continuous_snd.comp continuous_snd)).max continuous_fst).min
(continuous_fst.comp continuous_snd))
/- TODO : When `continuity` gets quicker, change the proof back to :
`begin`
`simp only [has_coe_to_fun.coe, coe_fn, path.truncate],`
`continuity,`
`exact continuous_subtype_coe`
`end` -/
@[continuity]
lemma truncate_const_continuous_family {X : Type*} [topological_space X] {a b : X}
(γ : path a b) (t : ℝ) : continuous ↿(γ.truncate t) :=
have key : continuous (λ x, (t, x) : ℝ × I → ℝ × ℝ × I) := continuous_const.prod_mk continuous_id,
by convert γ.truncate_continuous_family.comp key
@[simp] lemma truncate_self {X : Type*} [topological_space X] {a b : X}
(γ : path a b) (t : ℝ) : γ.truncate t t = (path.refl $ γ.extend t).cast (by rw min_self) rfl :=
begin
ext x,
rw cast_coe,
simp only [truncate, has_coe_to_fun.coe, coe_fn, refl, min_def, max_def],
split_ifs with h₁ h₂; congr,
exact le_antisymm ‹_› ‹_›
end
@[simp] lemma truncate_zero_zero {X : Type*} [topological_space X] {a b : X} (γ : path a b) :
γ.truncate 0 0 = (path.refl a).cast (by rw [min_self, γ.extend_zero]) γ.extend_zero :=
by convert γ.truncate_self 0; exact γ.extend_zero.symm
@[simp] lemma truncate_one_one {X : Type*} [topological_space X] {a b : X} (γ : path a b) :
γ.truncate 1 1 = (path.refl b).cast (by rw [min_self, γ.extend_one]) γ.extend_one :=
by convert γ.truncate_self 1; exact γ.extend_one.symm
@[simp] lemma truncate_zero_one {X : Type*} [topological_space X] {a b : X}
(γ : path a b) : γ.truncate 0 1 = γ.cast (by simp [zero_le_one, extend_zero]) (by simp) :=
begin
ext x,
rw cast_coe,
have : ↑x ∈ (Icc 0 1 : set ℝ) := x.2,
rw [truncate, coe_mk, max_eq_left this.1, min_eq_left this.2, extend_extends']
end
/-! #### Reparametrising a path -/
/--
Given a path `γ` and a function `f : I → I` where `f 0 = 0` and `f 1 = 1`, `γ.reparam f` is the
path defined by `γ ∘ f`.
-/
def reparam (γ : path x y) (f : I → I) (hfcont : continuous f) (hf₀ : f 0 = 0) (hf₁ : f 1 = 1) :
path x y :=
{ to_fun := γ ∘ f,
continuous_to_fun := by continuity,
source' := by simp [hf₀],
target' := by simp [hf₁] }
@[simp]
lemma coe_to_fun (γ : path x y) {f : I → I} (hfcont : continuous f) (hf₀ : f 0 = 0)
(hf₁ : f 1 = 1) : ⇑(γ.reparam f hfcont hf₀ hf₁) = γ ∘ f := rfl
@[simp]
lemma reparam_id (γ : path x y) : γ.reparam id continuous_id rfl rfl = γ :=
by { ext, refl }
lemma range_reparam (γ : path x y) {f : I → I} (hfcont : continuous f) (hf₀ : f 0 = 0)
(hf₁ : f 1 = 1) : range ⇑(γ.reparam f hfcont hf₀ hf₁) = range γ :=
begin
change range (γ ∘ f) = range γ,
have : range f = univ,
{ rw range_iff_surjective,
intro t,
have h₁ : continuous (Icc_extend (@zero_le_one ℝ _) f),
{ continuity },
have := intermediate_value_Icc (@zero_le_one ℝ _) h₁.continuous_on,
{ rw [Icc_extend_left, Icc_extend_right] at this,
change Icc (f 0) (f 1) ⊆ _ at this,
rw [hf₀, hf₁] at this,
rcases this t.2 with ⟨w, hw₁, hw₂⟩,
rw Icc_extend_of_mem _ _ hw₁ at hw₂,
use [⟨w, hw₁⟩, hw₂] } },
rw [range_comp, this, image_univ],
end
lemma refl_reparam {f : I → I} (hfcont : continuous f) (hf₀ : f 0 = 0)
(hf₁ : f 1 = 1) : (refl x).reparam f hfcont hf₀ hf₁ = refl x :=
begin
ext,
simp,
end
end path
/-! ### Being joined by a path -/
/-- The relation "being joined by a path". This is an equivalence relation. -/
def joined (x y : X) : Prop :=
nonempty (path x y)
@[refl] lemma joined.refl (x : X) : joined x x :=
⟨path.refl x⟩
/-- When two points are joined, choose some path from `x` to `y`. -/
def joined.some_path (h : joined x y) : path x y :=
nonempty.some h
@[symm] lemma joined.symm {x y : X} (h : joined x y) : joined y x :=
⟨h.some_path.symm⟩
@[trans] lemma joined.trans {x y z : X} (hxy : joined x y) (hyz : joined y z) :
joined x z :=
⟨hxy.some_path.trans hyz.some_path⟩
variables (X)
/-- The setoid corresponding the equivalence relation of being joined by a continuous path. -/
def path_setoid : setoid X :=
{ r := joined,
iseqv := mk_equivalence _ joined.refl (λ x y, joined.symm) (λ x y z, joined.trans) }
/-- The quotient type of points of a topological space modulo being joined by a continuous path. -/
def zeroth_homotopy := quotient (path_setoid X)
instance : inhabited (zeroth_homotopy ℝ) := ⟨@quotient.mk ℝ (path_setoid ℝ) 0⟩
variables {X}
/-! ### Being joined by a path inside a set -/
/-- The relation "being joined by a path in `F`". Not quite an equivalence relation since it's not
reflexive for points that do not belong to `F`. -/
def joined_in (F : set X) (x y : X) : Prop :=
∃ γ : path x y, ∀ t, γ t ∈ F
variables {F : set X}
lemma joined_in.mem (h : joined_in F x y) : x ∈ F ∧ y ∈ F :=
begin
rcases h with ⟨γ, γ_in⟩,
have : γ 0 ∈ F ∧ γ 1 ∈ F, by { split; apply γ_in },
simpa using this
end
lemma joined_in.source_mem (h : joined_in F x y) : x ∈ F :=
h.mem.1
lemma joined_in.target_mem (h : joined_in F x y) : y ∈ F :=
h.mem.2
/-- When `x` and `y` are joined in `F`, choose a path from `x` to `y` inside `F` -/
def joined_in.some_path (h : joined_in F x y) : path x y :=
classical.some h
lemma joined_in.some_path_mem (h : joined_in F x y) (t : I) : h.some_path t ∈ F :=
classical.some_spec h t
/-- If `x` and `y` are joined in the set `F`, then they are joined in the subtype `F`. -/
lemma joined_in.joined_subtype (h : joined_in F x y) :
joined (⟨x, h.source_mem⟩ : F) (⟨y, h.target_mem⟩ : F) :=
⟨{ to_fun := λ t, ⟨h.some_path t, h.some_path_mem t⟩,
continuous_to_fun := by continuity,
source' := by simp,
target' := by simp }⟩
lemma joined_in.of_line {f : ℝ → X} (hf : continuous_on f I) (h₀ : f 0 = x) (h₁ : f 1 = y)
(hF : f '' I ⊆ F) : joined_in F x y :=
⟨path.of_line hf h₀ h₁, λ t, hF $ path.of_line_mem hf h₀ h₁ t⟩
lemma joined_in.joined (h : joined_in F x y) : joined x y :=
⟨h.some_path⟩
lemma joined_in_iff_joined (x_in : x ∈ F) (y_in : y ∈ F) :
joined_in F x y ↔ joined (⟨x, x_in⟩ : F) (⟨y, y_in⟩ : F) :=
⟨λ h, h.joined_subtype, λ h, ⟨h.some_path.map continuous_subtype_coe, by simp⟩⟩
@[simp] lemma joined_in_univ : joined_in univ x y ↔ joined x y :=
by simp [joined_in, joined, exists_true_iff_nonempty]
lemma joined_in.mono {U V : set X} (h : joined_in U x y) (hUV : U ⊆ V) : joined_in V x y :=
⟨h.some_path, λ t, hUV (h.some_path_mem t)⟩
lemma joined_in.refl (h : x ∈ F) : joined_in F x x :=
⟨path.refl x, λ t, h⟩
@[symm] lemma joined_in.symm (h : joined_in F x y) : joined_in F y x :=
begin
cases h.mem with hx hy,
simp [joined_in_iff_joined, *] at *,
exact h.symm
end
lemma joined_in.trans (hxy : joined_in F x y) (hyz : joined_in F y z) : joined_in F x z :=
begin
cases hxy.mem with hx hy,
cases hyz.mem with hx hy,
simp [joined_in_iff_joined, *] at *,
exact hxy.trans hyz
end
/-! ### Path component -/
/-- The path component of `x` is the set of points that can be joined to `x`. -/
def path_component (x : X) := {y | joined x y}
@[simp] lemma mem_path_component_self (x : X) : x ∈ path_component x :=
joined.refl x
@[simp] lemma path_component.nonempty (x : X) : (path_component x).nonempty :=
⟨x, mem_path_component_self x⟩
lemma mem_path_component_of_mem (h : x ∈ path_component y) : y ∈ path_component x :=
joined.symm h
lemma path_component_symm : x ∈ path_component y ↔ y ∈ path_component x :=
⟨λ h, mem_path_component_of_mem h, λ h, mem_path_component_of_mem h⟩
lemma path_component_congr (h : x ∈ path_component y) : path_component x = path_component y :=
begin
ext z,
split,
{ intro h',
rw path_component_symm,
exact (h.trans h').symm },
{ intro h',
rw path_component_symm at h' ⊢,
exact h'.trans h },
end
lemma path_component_subset_component (x : X) : path_component x ⊆ connected_component x :=
λ y h, (is_connected_range h.some_path.continuous).subset_connected_component
⟨0, by simp⟩ ⟨1, by simp⟩
/-- The path component of `x` in `F` is the set of points that can be joined to `x` in `F`. -/
def path_component_in (x : X) (F : set X) := {y | joined_in F x y}
@[simp] lemma path_component_in_univ (x : X) : path_component_in x univ = path_component x :=
by simp [path_component_in, path_component, joined_in, joined, exists_true_iff_nonempty]
lemma joined.mem_path_component (hyz : joined y z) (hxy : y ∈ path_component x) :
z ∈ path_component x :=
hxy.trans hyz
/-! ### Path connected sets -/
/-- A set `F` is path connected if it contains a point that can be joined to all other in `F`. -/
def is_path_connected (F : set X) : Prop := ∃ x ∈ F, ∀ {y}, y ∈ F → joined_in F x y
lemma is_path_connected_iff_eq : is_path_connected F ↔ ∃ x ∈ F, path_component_in x F = F :=
begin
split ; rintros ⟨x, x_in, h⟩ ; use [x, x_in],
{ ext y,
exact ⟨λ hy, hy.mem.2, h⟩ },
{ intros y y_in,
rwa ← h at y_in },
end
lemma is_path_connected.joined_in (h : is_path_connected F) : ∀ x y ∈ F, joined_in F x y :=
λ x y x_in y_in, let ⟨b, b_in, hb⟩ := h in (hb x_in).symm.trans (hb y_in)
lemma is_path_connected_iff : is_path_connected F ↔ F.nonempty ∧ ∀ x y ∈ F, joined_in F x y :=
⟨λ h, ⟨let ⟨b, b_in, hb⟩ := h in ⟨b, b_in⟩, h.joined_in⟩,
λ ⟨⟨b, b_in⟩, h⟩, ⟨b, b_in, λ x x_in, h b x b_in x_in⟩⟩
lemma is_path_connected.image {Y : Type*} [topological_space Y] (hF : is_path_connected F)
{f : X → Y} (hf : continuous f) : is_path_connected (f '' F) :=
begin
rcases hF with ⟨x, x_in, hx⟩,
use [f x, mem_image_of_mem f x_in],
rintros _ ⟨y, y_in, rfl⟩,
exact ⟨(hx y_in).some_path.map hf, λ t, ⟨_, (hx y_in).some_path_mem t, rfl⟩⟩,
end
lemma is_path_connected.mem_path_component (h : is_path_connected F) (x_in : x ∈ F) (y_in : y ∈ F) :
y ∈ path_component x :=
(h.joined_in x y x_in y_in).joined
lemma is_path_connected.subset_path_component (h : is_path_connected F) (x_in : x ∈ F) :
F ⊆ path_component x :=
λ y y_in, h.mem_path_component x_in y_in
lemma is_path_connected.union {U V : set X} (hU : is_path_connected U) (hV : is_path_connected V)
(hUV : (U ∩ V).nonempty) : is_path_connected (U ∪ V) :=
begin
rcases hUV with ⟨x, xU, xV⟩,
use [x, or.inl xU],
rintros y (yU | yV),
{ exact (hU.joined_in x y xU yU).mono (subset_union_left U V) },
{ exact (hV.joined_in x y xV yV).mono (subset_union_right U V) },
end
/-- If a set `W` is path-connected, then it is also path-connected when seen as a set in a smaller
ambient type `U` (when `U` contains `W`). -/
lemma is_path_connected.preimage_coe {U W : set X} (hW : is_path_connected W) (hWU : W ⊆ U) :
is_path_connected ((coe : U → X) ⁻¹' W) :=
begin
rcases hW with ⟨x, x_in, hx⟩,
use [⟨x, hWU x_in⟩, by simp [x_in]],
rintros ⟨y, hyU⟩ hyW,
exact ⟨(hx hyW).joined_subtype.some_path.map (continuous_inclusion hWU), by simp⟩
end
lemma is_path_connected.exists_path_through_family
{X : Type*} [topological_space X] {n : ℕ} {s : set X} (h : is_path_connected s)
(p : fin (n+1) → X) (hp : ∀ i, p i ∈ s) :
∃ γ : path (p 0) (p n), (range γ ⊆ s) ∧ (∀ i, p i ∈ range γ) :=
begin
let p' : ℕ → X := λ k, if h : k < n+1 then p ⟨k, h⟩ else p ⟨0, n.zero_lt_succ⟩,
obtain ⟨γ, hγ⟩ : ∃ (γ : path (p' 0) (p' n)), (∀ i ≤ n, p' i ∈ range γ) ∧ range γ ⊆ s,
{ have hp' : ∀ i ≤ n, p' i ∈ s,
{ intros i hi,
simp [p', nat.lt_succ_of_le hi, hp] },
clear_value p',
clear hp p,
induction n with n hn,
{ use path.refl (p' 0),
{ split,
{ rintros i hi, rw nat.le_zero_iff.mp hi, exact ⟨0, rfl⟩ },
{ rw range_subset_iff, rintros x, exact hp' 0 (le_refl _) } } },
{ rcases hn (λ i hi, hp' i $ nat.le_succ_of_le hi) with ⟨γ₀, hγ₀⟩,
rcases h.joined_in (p' n) (p' $ n+1) (hp' n n.le_succ) (hp' (n+1) $ le_refl _) with ⟨γ₁, hγ₁⟩,
let γ : path (p' 0) (p' $ n+1) := γ₀.trans γ₁,
use γ,
have range_eq : range γ = range γ₀ ∪ range γ₁ := γ₀.trans_range γ₁,
split,
{ rintros i hi,
by_cases hi' : i ≤ n,
{ rw range_eq,
left,
exact hγ₀.1 i hi' },
{ rw [not_le, ← nat.succ_le_iff] at hi',
have : i = n.succ := by linarith,
rw this,
use 1,
exact γ.target } },
{ rw range_eq,
apply union_subset hγ₀.2,
rw range_subset_iff,
exact hγ₁ } } },
have hpp' : ∀ k < n+1, p k = p' k,
{ intros k hk, simp only [p', hk, dif_pos], congr, ext, rw fin.coe_coe_of_lt hk, norm_cast },
use γ.cast (hpp' 0 n.zero_lt_succ) (hpp' n n.lt_succ_self),
simp only [γ.cast_coe],
refine and.intro hγ.2 _,
rintros ⟨i, hi⟩,
convert hγ.1 i (nat.le_of_lt_succ hi), rw ← hpp' i hi,
congr,
ext,
rw fin.coe_coe_of_lt hi,
norm_cast
end
lemma is_path_connected.exists_path_through_family'
{X : Type*} [topological_space X] {n : ℕ} {s : set X} (h : is_path_connected s)
(p : fin (n+1) → X) (hp : ∀ i, p i ∈ s) :
∃ (γ : path (p 0) (p n)) (t : fin (n + 1) → I), (∀ t, γ t ∈ s) ∧ ∀ i, γ (t i) = p i :=
begin
rcases h.exists_path_through_family p hp with ⟨γ, hγ⟩,
rcases hγ with ⟨h₁, h₂⟩,
simp only [range, mem_set_of_eq] at h₂,
rw range_subset_iff at h₁,
choose! t ht using h₂,
exact ⟨γ, t, h₁, ht⟩
end
/-! ### Path connected spaces -/
/-- A topological space is path-connected if it is non-empty and every two points can be
joined by a continuous path. -/
class path_connected_space (X : Type*) [topological_space X] : Prop :=
(nonempty : nonempty X)
(joined : ∀ x y : X, joined x y)
attribute [instance, priority 50] path_connected_space.nonempty
lemma path_connected_space_iff_zeroth_homotopy :
path_connected_space X ↔ nonempty (zeroth_homotopy X) ∧ subsingleton (zeroth_homotopy X) :=
begin
letI := path_setoid X,
split,
{ introI h,
refine ⟨(nonempty_quotient_iff _).mpr h.1, ⟨_⟩⟩,
rintros ⟨x⟩ ⟨y⟩,
exact quotient.sound (path_connected_space.joined x y) },
{ unfold zeroth_homotopy,
rintros ⟨h, h'⟩,
resetI,
exact ⟨(nonempty_quotient_iff _).mp h, λ x y, quotient.exact $ subsingleton.elim ⟦x⟧ ⟦y⟧⟩ },
end
namespace path_connected_space
variables [path_connected_space X]
/-- Use path-connectedness to build a path between two points. -/
def some_path (x y : X) : path x y :=
nonempty.some (joined x y)
end path_connected_space
lemma is_path_connected_iff_path_connected_space : is_path_connected F ↔ path_connected_space F :=
begin
rw is_path_connected_iff,
split,
{ rintro ⟨⟨x, x_in⟩, h⟩,
refine ⟨⟨⟨x, x_in⟩⟩, _⟩,
rintros ⟨y, y_in⟩ ⟨z, z_in⟩,
have H := h y z y_in z_in,
rwa joined_in_iff_joined y_in z_in at H },
{ rintros ⟨⟨x, x_in⟩, H⟩,
refine ⟨⟨x, x_in⟩, λ y z y_in z_in, _⟩,
rw joined_in_iff_joined y_in z_in,
apply H }
end
lemma path_connected_space_iff_univ : path_connected_space X ↔ is_path_connected (univ : set X) :=
begin
split,
{ introI h,
inhabit X,
refine ⟨default X, mem_univ _, _⟩,
simpa using path_connected_space.joined (default X) },
{ intro h,
have h' := h.joined_in,
cases h with x h,
exact ⟨⟨x⟩, by simpa using h'⟩ },
end
lemma path_connected_space_iff_eq : path_connected_space X ↔ ∃ x : X, path_component x = univ :=
by simp [path_connected_space_iff_univ, is_path_connected_iff_eq]
@[priority 100] -- see Note [lower instance priority]
instance path_connected_space.connected_space [path_connected_space X] : connected_space X :=
begin
rw connected_space_iff_connected_component,
rcases is_path_connected_iff_eq.mp (path_connected_space_iff_univ.mp ‹_›) with ⟨x, x_in, hx⟩,
use x,
rw ← univ_subset_iff,
exact (by simpa using hx : path_component x = univ) ▸ path_component_subset_component x
end
namespace path_connected_space
variables [path_connected_space X]
lemma exists_path_through_family {n : ℕ} (p : fin (n+1) → X) :
∃ γ : path (p 0) (p n), (∀ i, p i ∈ range γ) :=
begin
have : is_path_connected (univ : set X) := path_connected_space_iff_univ.mp (by apply_instance),
rcases this.exists_path_through_family p (λ i, true.intro) with ⟨γ, -, h⟩,
exact ⟨γ, h⟩
end
lemma exists_path_through_family' {n : ℕ} (p : fin (n+1) → X) :
∃ (γ : path (p 0) (p n)) (t : fin (n + 1) → I), ∀ i, γ (t i) = p i :=
begin
have : is_path_connected (univ : set X) := path_connected_space_iff_univ.mp (by apply_instance),
rcases this.exists_path_through_family' p (λ i, true.intro) with ⟨γ, t, -, h⟩,
exact ⟨γ, t, h⟩
end
end path_connected_space
/-! ### Locally path connected spaces -/
/-- A topological space is locally path connected, at every point, path connected
neighborhoods form a neighborhood basis. -/
class loc_path_connected_space (X : Type*) [topological_space X] : Prop :=
(path_connected_basis : ∀ x : X, (𝓝 x).has_basis (λ s : set X, s ∈ 𝓝 x ∧ is_path_connected s) id)
export loc_path_connected_space (path_connected_basis)
lemma loc_path_connected_of_bases {p : ι → Prop} {s : X → ι → set X}
(h : ∀ x, (𝓝 x).has_basis p (s x)) (h' : ∀ x i, p i → is_path_connected (s x i)) :
loc_path_connected_space X :=
begin
constructor,
intro x,
apply (h x).to_has_basis,
{ intros i pi,
exact ⟨s x i, ⟨(h x).mem_of_mem pi, h' x i pi⟩, by refl⟩ },
{ rintros U ⟨U_in, hU⟩,
rcases (h x).mem_iff.mp U_in with ⟨i, pi, hi⟩,
tauto }
end
lemma path_connected_space_iff_connected_space [loc_path_connected_space X] :
path_connected_space X ↔ connected_space X :=
begin
split,
{ introI h,
apply_instance },
{ introI hX,
inhabit X,
let x₀ := default X,
rw path_connected_space_iff_eq,
use x₀,
refine eq_univ_of_nonempty_clopen (by simp) ⟨_, _⟩,
{ rw is_open_iff_mem_nhds,
intros y y_in,
rcases (path_connected_basis y).ex_mem with ⟨U, ⟨U_in, hU⟩⟩,
apply mem_of_superset U_in,
rw ← path_component_congr y_in,
exact hU.subset_path_component (mem_of_mem_nhds U_in) },
{ rw is_closed_iff_nhds,
intros y H,
rcases (path_connected_basis y).ex_mem with ⟨U, ⟨U_in, hU⟩⟩,
rcases H U U_in with ⟨z, hz, hz'⟩,
exact ((hU.joined_in z y hz $ mem_of_mem_nhds U_in).joined.mem_path_component hz') } },
end
lemma path_connected_subset_basis [loc_path_connected_space X] {U : set X} (h : is_open U)
(hx : x ∈ U) : (𝓝 x).has_basis (λ s : set X, s ∈ 𝓝 x ∧ is_path_connected s ∧ s ⊆ U) id :=
(path_connected_basis x).has_basis_self_subset (is_open.mem_nhds h hx)
lemma loc_path_connected_of_is_open [loc_path_connected_space X] {U : set X} (h : is_open U) :
loc_path_connected_space U :=
⟨begin
rintros ⟨x, x_in⟩,
rw nhds_subtype_eq_comap,
constructor,
intros V,
rw (has_basis.comap (coe : U → X) (path_connected_subset_basis h x_in)).mem_iff,
split,
{ rintros ⟨W, ⟨W_in, hW, hWU⟩, hWV⟩,
exact ⟨coe ⁻¹' W, ⟨⟨preimage_mem_comap W_in, hW.preimage_coe hWU⟩, hWV⟩⟩ },
{ rintros ⟨W, ⟨W_in, hW⟩, hWV⟩,
refine ⟨coe '' W, ⟨filter.image_coe_mem_of_mem_comap (is_open.mem_nhds h x_in) W_in,
hW.image continuous_subtype_coe, subtype.coe_image_subset U W⟩, _⟩,
rintros x ⟨y, ⟨y_in, hy⟩⟩,
rw ← subtype.coe_injective hy,
tauto },
end⟩
lemma is_open.is_connected_iff_is_path_connected
[loc_path_connected_space X] {U : set X} (U_op : is_open U) :
is_path_connected U ↔ is_connected U :=
begin
rw [is_connected_iff_connected_space, is_path_connected_iff_path_connected_space],
haveI := loc_path_connected_of_is_open U_op,
exact path_connected_space_iff_connected_space
end
|
d0c3af192c06e8aa5b94c899cc5bedab7cb26027 | 302c785c90d40ad3d6be43d33bc6a558354cc2cf | /src/tactic/monotonicity/interactive.lean | 8e7a07e384f8f1a00cee89c55d45dce395714347 | [
"Apache-2.0"
] | permissive | ilitzroth/mathlib | ea647e67f1fdfd19a0f7bdc5504e8acec6180011 | 5254ef14e3465f6504306132fe3ba9cec9ffff16 | refs/heads/master | 1,680,086,661,182 | 1,617,715,647,000 | 1,617,715,647,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 23,473 | lean | /-
Copyright (c) 2019 Simon Hudon. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Simon Hudon
-/
import tactic.monotonicity.basic
import control.traversable
import control.traversable.derive
import data.dlist
variables {a b c p : Prop}
namespace tactic.interactive
open lean lean.parser interactive
open interactive.types
open tactic
local postfix `?`:9001 := optional
local postfix *:9001 := many
meta inductive mono_function (elab : bool := tt)
| non_assoc : expr elab → list (expr elab) → list (expr elab) → mono_function
| assoc : expr elab → option (expr elab) → option (expr elab) → mono_function
| assoc_comm : expr elab → expr elab → mono_function
meta instance : decidable_eq mono_function :=
by mk_dec_eq_instance
meta def mono_function.to_tactic_format : mono_function → tactic format
| (mono_function.non_assoc fn xs ys) := do
fn' ← pp fn,
xs' ← mmap pp xs,
ys' ← mmap pp ys,
return format!"{fn'} {xs'} _ {ys'}"
| (mono_function.assoc fn xs ys) := do
fn' ← pp fn,
xs' ← pp xs,
ys' ← pp ys,
return format!"{fn'} {xs'} _ {ys'}"
| (mono_function.assoc_comm fn xs) := do
fn' ← pp fn,
xs' ← pp xs,
return format!"{fn'} _ {xs'}"
meta instance has_to_tactic_format_mono_function : has_to_tactic_format mono_function :=
{ to_tactic_format := mono_function.to_tactic_format }
@[derive traversable]
meta structure ac_mono_ctx' (rel : Type) :=
(to_rel : rel)
(function : mono_function)
(left right rel_def : expr)
@[reducible]
meta def ac_mono_ctx := ac_mono_ctx' (option (expr → expr → expr))
@[reducible]
meta def ac_mono_ctx_ne := ac_mono_ctx' (expr → expr → expr)
meta def ac_mono_ctx.to_tactic_format (ctx : ac_mono_ctx) : tactic format :=
do fn ← pp ctx.function,
l ← pp ctx.left,
r ← pp ctx.right,
rel ← pp ctx.rel_def,
return format!"{{ function := {fn}\n, left := {l}\n, right := {r}\n, rel_def := {rel} }"
meta instance has_to_tactic_format_mono_ctx : has_to_tactic_format ac_mono_ctx :=
{ to_tactic_format := ac_mono_ctx.to_tactic_format }
meta def as_goal (e : expr) (tac : tactic unit) : tactic unit :=
do gs ← get_goals,
set_goals [e],
tac,
set_goals gs
open list (hiding map) functor dlist
section config
parameter opt : mono_cfg
parameter asms : list expr
meta def unify_with_instance (e : expr) : tactic unit :=
as_goal e $
apply_instance
<|>
apply_opt_param
<|>
apply_auto_param
<|>
tactic.solve_by_elim { lemmas := some asms }
<|>
reflexivity
<|>
applyc ``id
<|>
return ()
private meta def match_rule_head (p : expr)
: list expr → expr → expr → tactic expr
| vs e t :=
(unify t p >> mmap' unify_with_instance vs >> instantiate_mvars e)
<|>
do (expr.pi _ _ d b) ← return t | failed,
v ← mk_meta_var d,
match_rule_head (v::vs) (expr.app e v) (b.instantiate_var v)
meta def pi_head : expr → tactic expr
| (expr.pi n _ t b) :=
do v ← mk_meta_var t,
pi_head (b.instantiate_var v)
| e := return e
meta def delete_expr (e : expr)
: list expr → tactic (option (list expr))
| [] := return none
| (x :: xs) :=
(compare opt e x >> return (some xs))
<|>
(map (cons x) <$> delete_expr xs)
meta def match_ac'
: list expr → list expr → tactic (list expr × list expr × list expr)
| es (x :: xs) := do
es' ← delete_expr x es,
match es' with
| (some es') := do
(c,l,r) ← match_ac' es' xs, return (x::c,l,r)
| none := do
(c,l,r) ← match_ac' es xs, return (c,l,x::r)
end
| es [] := do
return ([],es,[])
meta def match_ac (l : list expr) (r : list expr)
: tactic (list expr × list expr × list expr) :=
do (s',l',r') ← match_ac' l r,
s' ← mmap instantiate_mvars s',
l' ← mmap instantiate_mvars l',
r' ← mmap instantiate_mvars r',
return (s',l',r')
meta def match_prefix
: list expr → list expr → tactic (list expr × list expr × list expr)
| (x :: xs) (y :: ys) :=
(do compare opt x y,
prod.map ((::) x) id <$> match_prefix xs ys)
<|> return ([],x :: xs,y :: ys)
| xs ys := return ([],xs,ys)
/--
`(prefix,left,right,suffix) ← match_assoc unif l r` finds the
longest prefix and suffix common to `l` and `r` and
returns them along with the differences -/
meta def match_assoc (l : list expr) (r : list expr)
: tactic (list expr × list expr × list expr × list expr) :=
do (pre,l₁,r₁) ← match_prefix l r,
(suf,l₂,r₂) ← match_prefix (reverse l₁) (reverse r₁),
return (pre,reverse l₂,reverse r₂,reverse suf)
meta def check_ac : expr → tactic (bool × bool × option (expr × expr × expr) × expr)
| (expr.app (expr.app f x) y) :=
do t ← infer_type x,
a ← try_core $ to_expr ``(is_associative %%t %%f) >>= mk_instance,
c ← try_core $ to_expr ``(is_commutative %%t %%f) >>= mk_instance,
i ← try_core (do
v ← mk_meta_var t,
l_inst_p ← to_expr ``(is_left_id %%t %%f %%v),
r_inst_p ← to_expr ``(is_right_id %%t %%f %%v),
l_v ← mk_meta_var l_inst_p,
r_v ← mk_meta_var r_inst_p ,
l_id ← mk_mapp `is_left_id.left_id [some t,f,v,some l_v],
mk_instance l_inst_p >>= unify l_v,
r_id ← mk_mapp `is_right_id.right_id [none,f,v,some r_v],
mk_instance r_inst_p >>= unify r_v,
v' ← instantiate_mvars v,
return (l_id,r_id,v')),
return (a.is_some,c.is_some,i,f)
| _ := return (ff,ff,none,expr.var 1)
meta def parse_assoc_chain' (f : expr) : expr → tactic (dlist expr)
| e :=
(do (expr.app (expr.app f' x) y) ← return e,
is_def_eq f f',
(++) <$> parse_assoc_chain' x <*> parse_assoc_chain' y)
<|> return (singleton e)
meta def parse_assoc_chain (f : expr) : expr → tactic (list expr) :=
map dlist.to_list ∘ parse_assoc_chain' f
meta def fold_assoc (op : expr) : option (expr × expr × expr) → list expr → option (expr × list expr)
| _ (x::xs) := some (foldl (expr.app ∘ expr.app op) x xs, [])
| none [] := none
| (some (l_id,r_id,x₀)) [] := some (x₀,[l_id,r_id])
meta def fold_assoc1 (op : expr) : list expr → option expr
| (x::xs) := some $ foldl (expr.app ∘ expr.app op) x xs
| [] := none
meta def same_function_aux
: list expr → list expr → expr → expr → tactic (expr × list expr × list expr)
| xs₀ xs₁ (expr.app f₀ a₀) (expr.app f₁ a₁) :=
same_function_aux (a₀ :: xs₀) (a₁ :: xs₁) f₀ f₁
| xs₀ xs₁ e₀ e₁ := is_def_eq e₀ e₁ >> return (e₀,xs₀,xs₁)
meta def same_function : expr → expr → tactic (expr × list expr × list expr) :=
same_function_aux [] []
meta def parse_ac_mono_function (l r : expr)
: tactic (expr × expr × list expr × mono_function) :=
do (full_f,ls,rs) ← same_function l r,
(a,c,i,f) ← check_ac l,
if a
then if c
then do
(s,ls,rs) ← monad.join (match_ac
<$> parse_assoc_chain f l
<*> parse_assoc_chain f r),
(l',l_id) ← fold_assoc f i ls,
(r',r_id) ← fold_assoc f i rs,
s' ← fold_assoc1 f s,
return (l',r',l_id ++ r_id,mono_function.assoc_comm f s')
else do -- a ∧ ¬ c
(pre,ls,rs,suff) ← monad.join (match_assoc
<$> parse_assoc_chain f l
<*> parse_assoc_chain f r),
(l',l_id) ← fold_assoc f i ls,
(r',r_id) ← fold_assoc f i rs,
let pre' := fold_assoc1 f pre,
let suff' := fold_assoc1 f suff,
return (l',r',l_id ++ r_id,mono_function.assoc f pre' suff')
else do -- ¬ a
(xs₀,x₀,x₁,xs₁) ← find_one_difference opt ls rs,
return (x₀,x₁,[],mono_function.non_assoc full_f xs₀ xs₁)
meta def parse_ac_mono_function' (l r : pexpr) :=
do l' ← to_expr l,
r' ← to_expr r,
parse_ac_mono_function l' r'
meta def ac_monotonicity_goal : expr → tactic (expr × expr × list expr × ac_mono_ctx)
| `(%%e₀ → %%e₁) :=
do (l,r,id_rs,f) ← parse_ac_mono_function e₀ e₁,
t₀ ← infer_type e₀,
t₁ ← infer_type e₁,
rel_def ← to_expr ``(λ x₀ x₁, (x₀ : %%t₀) → (x₁ : %%t₁)),
return (e₀, e₁, id_rs,
{ function := f
, left := l, right := r
, to_rel := some $ expr.pi `x binder_info.default
, rel_def := rel_def })
| `(%%e₀ = %%e₁) :=
do (l,r,id_rs,f) ← parse_ac_mono_function e₀ e₁,
t₀ ← infer_type e₀,
t₁ ← infer_type e₁,
rel_def ← to_expr ``(λ x₀ x₁, (x₀ : %%t₀) = (x₁ : %%t₁)),
return (e₀, e₁, id_rs,
{ function := f
, left := l, right := r
, to_rel := none
, rel_def := rel_def })
| (expr.app (expr.app rel e₀) e₁) :=
do (l,r,id_rs,f) ← parse_ac_mono_function e₀ e₁,
return (e₀, e₁, id_rs,
{ function := f
, left := l, right := r
, to_rel := expr.app ∘ expr.app rel
, rel_def := rel })
| _ := fail "invalid monotonicity goal"
meta def bin_op_left (f : expr) : option expr → expr → expr
| none e := e
| (some e₀) e₁ := f.mk_app [e₀,e₁]
meta def bin_op (f a b : expr) : expr :=
f.mk_app [a,b]
meta def bin_op_right (f : expr) : expr → option expr → expr
| e none := e
| e₀ (some e₁) := f.mk_app [e₀,e₁]
meta def mk_fun_app : mono_function → expr → expr
| (mono_function.non_assoc f x y) z := f.mk_app (x ++ z :: y)
| (mono_function.assoc f x y) z := bin_op_left f x (bin_op_right f z y)
| (mono_function.assoc_comm f x) z := f.mk_app [z,x]
meta inductive mono_law
/- `assoc (l₀,r₀) (r₁,l₁)` gives first how to find rules to prove
x+(y₀+z) R x+(y₁+z);
if that fails, helps prove (x+y₀)+z R (x+y₁)+z -/
| assoc : expr × expr → expr × expr → mono_law
/- `congr r` gives the rule to prove `x = y → f x = f y` -/
| congr : expr → mono_law
| other : expr → mono_law
meta def mono_law.to_tactic_format : mono_law → tactic format
| (mono_law.other e) := do e ← pp e, return format!"other {e}"
| (mono_law.congr r) := do e ← pp r, return format!"congr {e}"
| (mono_law.assoc (x₀,x₁) (y₀,y₁)) :=
do x₀ ← pp x₀,
x₁ ← pp x₁,
y₀ ← pp y₀,
y₁ ← pp y₁,
return format!"assoc {x₀}; {x₁} | {y₀}; {y₁}"
meta instance has_to_tactic_format_mono_law : has_to_tactic_format mono_law :=
{ to_tactic_format := mono_law.to_tactic_format }
meta def mk_rel (ctx : ac_mono_ctx_ne) (f : expr → expr) : expr :=
ctx.to_rel (f ctx.left) (f ctx.right)
meta def mk_congr_args (fn : expr) (xs₀ xs₁ : list expr) (l r : expr) : tactic expr :=
do p ← mk_app `eq [fn.mk_app $ xs₀ ++ l :: xs₁,fn.mk_app $ xs₀ ++ r :: xs₁],
prod.snd <$> solve_aux p
(do iterate_exactly (xs₁.length) (applyc `congr_fun),
applyc `congr_arg)
meta def mk_congr_law (ctx : ac_mono_ctx) : tactic expr :=
match ctx.function with
| (mono_function.assoc f x₀ x₁) :=
if (x₀ <|> x₁).is_some
then mk_congr_args f x₀.to_monad x₁.to_monad ctx.left ctx.right
else failed
| (mono_function.assoc_comm f x₀) := mk_congr_args f [x₀] [] ctx.left ctx.right
| (mono_function.non_assoc f x₀ x₁) := mk_congr_args f x₀ x₁ ctx.left ctx.right
end
meta def mk_pattern (ctx : ac_mono_ctx) : tactic mono_law :=
match (sequence ctx : option (ac_mono_ctx' _)) with
| (some ctx) :=
match ctx.function with
| (mono_function.assoc f (some x) (some y)) :=
return $ mono_law.assoc
( mk_rel ctx (λ i, bin_op f x (bin_op f i y))
, mk_rel ctx (λ i, bin_op f i y))
( mk_rel ctx (λ i, bin_op f (bin_op f x i) y)
, mk_rel ctx (λ i, bin_op f x i))
| (mono_function.assoc f (some x) none) :=
return $ mono_law.other $
mk_rel ctx (λ e, mk_fun_app ctx.function e)
| (mono_function.assoc f none (some y)) :=
return $ mono_law.other $
mk_rel ctx (λ e, mk_fun_app ctx.function e)
| (mono_function.assoc f none none) :=
none
| _ :=
return $ mono_law.other $
mk_rel ctx (λ e, mk_fun_app ctx.function e)
end
| none := mono_law.congr <$> mk_congr_law ctx
end
meta def match_rule (pat : expr) (r : name) : tactic expr :=
do r' ← mk_const r,
t ← infer_type r',
t ← expr.dsimp t { fail_if_unchanged := ff } tt [] [simp_arg_type.expr ``(monotone)],
match_rule_head pat [] r' t
meta def find_lemma (pat : expr) : list name → tactic (list expr)
| [] := return []
| (r :: rs) :=
do (cons <$> match_rule pat r <|> pure id) <*> find_lemma rs
meta def match_chaining_rules (ls : list name) (x₀ x₁ : expr) : tactic (list expr) :=
do x' ← to_expr ``(%%x₁ → %%x₀),
r₀ ← find_lemma x' ls,
r₁ ← find_lemma x₁ ls,
return (expr.app <$> r₀ <*> r₁)
meta def find_rule (ls : list name) : mono_law → tactic (list expr)
| (mono_law.assoc (x₀,x₁) (y₀,y₁)) :=
(match_chaining_rules ls x₀ x₁)
<|> (match_chaining_rules ls y₀ y₁)
| (mono_law.congr r) := return [r]
| (mono_law.other p) := find_lemma p ls
universes u v
def apply_rel {α : Sort u} (R : α → α → Sort v) {x y : α}
(x' y' : α)
(h : R x y)
(hx : x = x')
(hy : y = y')
: R x' y' :=
by { rw [← hx,← hy], apply h }
meta def ac_refine (e : expr) : tactic unit :=
refine ``(eq.mp _ %%e) ; ac_refl
meta def one_line (e : expr) : tactic format :=
do lbl ← pp e,
asm ← infer_type e >>= pp,
return format!"\t{asm}\n"
meta def side_conditions (e : expr) : tactic format :=
do let vs := e.list_meta_vars,
ts ← mmap one_line vs.tail,
let r := e.get_app_fn.const_name,
return format!"{r}:\n{format.join ts}"
open monad
/-- tactic-facing function, similar to `interactive.tactic.generalize` with the
exception that meta variables -/
private meta def monotonicity.generalize' (h : name) (v : expr) (x : name) : tactic (expr × expr) :=
do tgt ← target,
t ← infer_type v,
tgt' ← do {
⟨tgt', _⟩ ← solve_aux tgt (tactic.generalize v x >> target),
to_expr ``(λ y : %%t, Π x, y = x → %%(tgt'.binding_body.lift_vars 0 1))
} <|> to_expr ``(λ y : %%t, Π x, %%v = x → %%tgt),
t ← head_beta (tgt' v) >>= assert h,
swap,
r ← mk_eq_refl v,
solve1 $ tactic.exact (t v r),
prod.mk <$> tactic.intro x <*> tactic.intro h
private meta def hide_meta_vars (tac : list expr → tactic unit) : tactic unit :=
focus1 $
do tgt ← target >>= instantiate_mvars,
tactic.change tgt,
ctx ← local_context,
let vs := tgt.list_meta_vars,
vs' ← mmap (λ v,
do h ← get_unused_name `h,
x ← get_unused_name `x,
prod.snd <$> monotonicity.generalize' h v x) vs,
tac ctx;
vs'.mmap' (try ∘ tactic.subst)
meta def hide_meta_vars' (tac : itactic) : itactic :=
hide_meta_vars $ λ _, tac
end config
meta def solve_mvar (v : expr) (tac : tactic unit) : tactic unit :=
do gs ← get_goals,
set_goals [v],
target >>= instantiate_mvars >>= tactic.change,
tac, done,
set_goals $ gs
def list.minimum_on {α β} [linear_order β] (f : α → β) : list α → list α
| [] := []
| (x :: xs) := prod.snd $ xs.foldl (λ ⟨k,a⟩ b,
let k' := f b in
if k < k' then (k,a)
else if k' < k then (k', [b])
else (k,b :: a)) (f x, [x])
open format mono_selection
meta def best_match {β} (xs : list expr) (tac : expr → tactic β) : tactic unit :=
do t ← target,
xs ← xs.mmap (λ x,
try_core $ prod.mk x <$> solve_aux t (tac x >> get_goals)),
let xs := xs.filter_map id,
let r := list.minimum_on (list.length ∘ prod.fst ∘ prod.snd) xs,
match r with
| [(_,gs,pr)] := tactic.exact pr >> set_goals gs
| [] := fail "no good match found"
| _ :=
do lmms ← r.mmap (λ ⟨l,gs,_⟩,
do ts ← gs.mmap infer_type,
msg ← ts.mmap pp,
pure $ foldl compose "\n\n" (list.intersperse "\n" $ to_fmt l.get_app_fn.const_name :: msg)),
let msg := foldl compose "" lmms,
fail format!"ambiguous match: {msg}\n\nTip: try asserting a side condition to distinguish between the lemmas"
end
meta def mono_aux (dir : parse side) :
tactic unit :=
do t ← target >>= instantiate_mvars,
ns ← get_monotonicity_lemmas t dir,
asms ← local_context,
rs ← find_lemma asms t ns,
focus1 $ () <$ best_match rs (λ law, tactic.refine $ to_pexpr law)
/--
- `mono` applies a monotonicity rule.
- `mono*` applies monotonicity rules repetitively.
- `mono with x ≤ y` or `mono with [0 ≤ x,0 ≤ y]` creates an assertion for the listed
propositions. Those help to select the right monotonicity rule.
- `mono left` or `mono right` is useful when proving strict orderings:
for `x + y < w + z` could be broken down into either
- left: `x ≤ w` and `y < z` or
- right: `x < w` and `y ≤ z`
- `mono using [rule1,rule2]` calls `simp [rule1,rule2]` before applying mono.
- The general syntax is `mono '*'? ('with' hyp | 'with' [hyp1,hyp2])? ('using' [hyp1,hyp2])? mono_cfg?
To use it, first import `tactic.monotonicity`.
Here is an example of mono:
```lean
example (x y z k : ℤ)
(h : 3 ≤ (4 : ℤ))
(h' : z ≤ y) :
(k + 3 + x) - y ≤ (k + 4 + x) - z :=
begin
mono, -- unfold `(-)`, apply add_le_add
{ -- ⊢ k + 3 + x ≤ k + 4 + x
mono, -- apply add_le_add, refl
-- ⊢ k + 3 ≤ k + 4
mono },
{ -- ⊢ -y ≤ -z
mono /- apply neg_le_neg -/ }
end
```
More succinctly, we can prove the same goal as:
```lean
example (x y z k : ℤ)
(h : 3 ≤ (4 : ℤ))
(h' : z ≤ y) :
(k + 3 + x) - y ≤ (k + 4 + x) - z :=
by mono*
```
-/
meta def mono (many : parse (tk "*")?)
(dir : parse side)
(hyps : parse $ tk "with" *> pexpr_list_or_texpr <|> pure [])
(simp_rules : parse $ tk "using" *> simp_arg_list <|> pure []) :
tactic unit :=
do hyps ← hyps.mmap (λ p, to_expr p >>= mk_meta_var),
hyps.mmap' (λ pr, do h ← get_unused_name `h, note h none pr),
when (¬ simp_rules.empty) (simp_core { } failed tt simp_rules [] (loc.ns [none]) >> skip),
if many.is_some
then repeat $ mono_aux dir
else mono_aux dir,
gs ← get_goals,
set_goals $ hyps ++ gs
add_tactic_doc
{ name := "mono",
category := doc_category.tactic,
decl_names := [`tactic.interactive.mono],
tags := ["monotonicity"] }
/--
transforms a goal of the form `f x ≼ f y` into `x ≤ y` using lemmas
marked as `monotonic`.
Special care is taken when `f` is the repeated application of an
associative operator and if the operator is commutative
-/
meta def ac_mono_aux (cfg : mono_cfg := { mono_cfg . }) :
tactic unit :=
hide_meta_vars $ λ asms,
do try `[simp only [sub_eq_add_neg]],
tgt ← target >>= instantiate_mvars,
(l,r,id_rs,g) ← ac_monotonicity_goal cfg tgt
<|> fail "monotonic context not found",
ns ← get_monotonicity_lemmas tgt both,
p ← mk_pattern g,
rules ← find_rule asms ns p <|> fail "no applicable rules found",
when (rules = []) (fail "no applicable rules found"),
err ← format.join <$> mmap side_conditions rules,
focus1 $ best_match rules (λ rule, do
t₀ ← mk_meta_var `(Prop),
v₀ ← mk_meta_var t₀,
t₁ ← mk_meta_var `(Prop),
v₁ ← mk_meta_var t₁,
tactic.refine $ ``(apply_rel %%(g.rel_def) %%l %%r %%rule %%v₀ %%v₁),
solve_mvar v₀ (try (any_of id_rs rewrite_target) >>
( done <|>
refl <|>
ac_refl <|>
`[simp only [is_associative.assoc]]) ),
solve_mvar v₁ (try (any_of id_rs rewrite_target) >>
( done <|>
refl <|>
ac_refl <|>
`[simp only [is_associative.assoc]]) ),
n ← num_goals,
iterate_exactly (n-1) (try $ solve1 $ apply_instance <|>
tactic.solve_by_elim { lemmas := some asms }))
open sum nat
/-- (repeat_until_or_at_most n t u): repeat tactic `t` at most n times or until u succeeds -/
meta def repeat_until_or_at_most : nat → tactic unit → tactic unit → tactic unit
| 0 t _ := fail "too many applications"
| (succ n) t u := u <|> (t >> repeat_until_or_at_most n t u)
meta def repeat_until : tactic unit → tactic unit → tactic unit :=
repeat_until_or_at_most 100000
@[derive _root_.has_reflect, derive _root_.inhabited]
inductive rep_arity : Type
| one | exactly (n : ℕ) | many
meta def repeat_or_not : rep_arity → tactic unit → option (tactic unit) → tactic unit
| rep_arity.one tac none := tac
| rep_arity.many tac none := repeat tac
| (rep_arity.exactly n) tac none := iterate_exactly' n tac
| rep_arity.one tac (some until) := tac >> until
| rep_arity.many tac (some until) := repeat_until tac until
| (rep_arity.exactly n) tac (some until) := iterate_exactly n tac >> until
meta def assert_or_rule : lean.parser (pexpr ⊕ pexpr) :=
(tk ":=" *> inl <$> texpr <|> (tk ":" *> inr <$> texpr))
meta def arity : lean.parser rep_arity :=
rep_arity.many <$ tk "*" <|>
rep_arity.exactly <$> (tk "^" *> small_nat) <|>
pure rep_arity.one
/--
`ac_mono` reduces the `f x ⊑ f y`, for some relation `⊑` and a
monotonic function `f` to `x ≺ y`.
`ac_mono*` unwraps monotonic functions until it can't.
`ac_mono^k`, for some literal number `k` applies monotonicity `k`
times.
`ac_mono h`, with `h` a hypothesis, unwraps monotonic functions and
uses `h` to solve the remaining goal. Can be combined with `*` or `^k`:
`ac_mono* h`
`ac_mono : p` asserts `p` and uses it to discharge the goal result
unwrapping a series of monotonic functions. Can be combined with * or
^k: `ac_mono* : p`
In the case where `f` is an associative or commutative operator,
`ac_mono` will consider any possible permutation of its arguments and
use the one the minimizes the difference between the left-hand side
and the right-hand side.
To use it, first import `tactic.monotonicity`.
`ac_mono` can be used as follows:
```lean
example (x y z k m n : ℕ)
(h₀ : z ≥ 0)
(h₁ : x ≤ y) :
(m + x + n) * z + k ≤ z * (y + n + m) + k :=
begin
ac_mono,
-- ⊢ (m + x + n) * z ≤ z * (y + n + m)
ac_mono,
-- ⊢ m + x + n ≤ y + n + m
ac_mono,
end
```
As with `mono*`, `ac_mono*` solves the goal in one go and so does
`ac_mono* h₁`. The latter syntax becomes especially interesting in the
following example:
```lean
example (x y z k m n : ℕ)
(h₀ : z ≥ 0)
(h₁ : m + x + n ≤ y + n + m) :
(m + x + n) * z + k ≤ z * (y + n + m) + k :=
by ac_mono* h₁.
```
By giving `ac_mono` the assumption `h₁`, we are asking `ac_refl` to
stop earlier than it would normally would.
-/
meta def ac_mono (rep : parse arity) :
parse assert_or_rule? →
opt_param mono_cfg { mono_cfg . } →
tactic unit
| none opt := focus1 $ repeat_or_not rep (ac_mono_aux opt) none
| (some (inl h)) opt :=
do focus1 $ repeat_or_not rep (ac_mono_aux opt) (some $ done <|> to_expr h >>= ac_refine)
| (some (inr t)) opt :=
do h ← i_to_expr t >>= assert `h,
tactic.swap,
focus1 $ repeat_or_not rep (ac_mono_aux opt) (some $ done <|> ac_refine h)
/-
TODO(Simon): with `ac_mono h` and `ac_mono : p` split the remaining
gaol if the provided rule does not solve it completely.
-/
add_tactic_doc
{ name := "ac_mono",
category := doc_category.tactic,
decl_names := [`tactic.interactive.ac_mono],
tags := ["monotonicity"] }
attribute [mono] and.imp or.imp
end tactic.interactive
|
ea2eb42e5ee21b95f6e8b7bc15d1f5463695827c | b7f22e51856f4989b970961f794f1c435f9b8f78 | /tests/lean/run/show2.lean | 2d6389ae487781795255b8974de99f5e715e3780 | [
"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 | 274 | lean | import data.nat
open nat algebra
example : ∀ a b : nat, a + b = b + a :=
show ∀ a b : nat, a + b = b + a
| 0 0 := rfl
| 0 (succ b) := by rewrite zero_add
| (succ a) 0 := by rewrite zero_add
| (succ a) (succ b) := by rewrite [succ_add, this]
|
d1ed81930de91d086f41fb8920562f0c61c184dc | 57c233acf9386e610d99ed20ef139c5f97504ba3 | /src/category_theory/types.lean | e671d88b15c75ca7d4d7f513560125945cecac28 | [
"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 | 10,578 | lean | /-
Copyright (c) 2017 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Stephen Morgan, Scott Morrison, Johannes Hölzl
-/
import category_theory.fully_faithful
import data.equiv.basic
/-!
# The category `Type`.
In this section we set up the theory so that Lean's types and functions between them
can be viewed as a `large_category` in our framework.
Lean can not transparently view a function as a morphism in this category, and needs a hint in
order to be able to type check. We provide the abbreviation `as_hom f` to guide type checking,
as well as a corresponding notation `↾ f`. (Entered as `\upr `.) The notation is enabled using
`open_locale category_theory.Type`.
We provide various simplification lemmas for functors and natural transformations valued in `Type`.
We define `ulift_functor`, from `Type u` to `Type (max u v)`, and show that it is fully faithful
(but not, of course, essentially surjective).
We prove some basic facts about the category `Type`:
* epimorphisms are surjections and monomorphisms are injections,
* `iso` is both `iso` and `equiv` to `equiv` (at least within a fixed universe),
* every type level `is_lawful_functor` gives a categorical functor `Type ⥤ Type`
(the corresponding fact about monads is in `src/category_theory/monad/types.lean`).
-/
namespace category_theory
-- morphism levels before object levels. See note [category_theory universes].
universes v v' w u u'
/- The `@[to_additive]` attribute is just a hint that expressions involving this instance can
still be additivized. -/
@[to_additive category_theory.types]
instance types : large_category (Type u) :=
{ hom := λ a b, (a → b),
id := λ a, id,
comp := λ _ _ _ f g, g ∘ f }
lemma types_hom {α β : Type u} : (α ⟶ β) = (α → β) := rfl
lemma types_id (X : Type u) : 𝟙 X = id := rfl
lemma types_comp {X Y Z : Type u} (f : X ⟶ Y) (g : Y ⟶ Z) : f ≫ g = g ∘ f := rfl
@[simp]
lemma types_id_apply (X : Type u) (x : X) : ((𝟙 X) : X → X) x = x := rfl
@[simp]
lemma types_comp_apply {X Y Z : Type u} (f : X ⟶ Y) (g : Y ⟶ Z) (x : X) : (f ≫ g) x = g (f x) := rfl
@[simp]
lemma hom_inv_id_apply {X Y : Type u} (f : X ≅ Y) (x : X) : f.inv (f.hom x) = x :=
congr_fun f.hom_inv_id x
@[simp]
lemma inv_hom_id_apply {X Y : Type u} (f : X ≅ Y) (y : Y) : f.hom (f.inv y) = y :=
congr_fun f.inv_hom_id y
/-- `as_hom f` helps Lean type check a function as a morphism in the category `Type`. -/
-- Unfortunately without this wrapper we can't use `category_theory` idioms, such as `is_iso f`.
abbreviation as_hom {α β : Type u} (f : α → β) : α ⟶ β := f
-- If you don't mind some notation you can use fewer keystrokes:
localized "notation `↾` f : 200 := category_theory.as_hom f"
in category_theory.Type -- type as \upr in VScode
section -- We verify the expected type checking behaviour of `as_hom`.
variables (α β γ : Type u) (f : α → β) (g : β → γ)
example : α → γ := ↾f ≫ ↾g
example [is_iso ↾f] : mono ↾f := by apply_instance
example [is_iso ↾f] : ↾f ≫ inv ↾f = 𝟙 α := by simp
end
namespace functor
variables {J : Type u} [category.{v} J]
/--
The sections of a functor `J ⥤ Type` are
the choices of a point `u j : F.obj j` for each `j`,
such that `F.map f (u j) = u j` for every morphism `f : j ⟶ j'`.
We later use these to define limits in `Type` and in many concrete categories.
-/
def sections (F : J ⥤ Type w) : set (Π j, F.obj j) :=
{ u | ∀ {j j'} (f : j ⟶ j'), F.map f (u j) = u j'}
end functor
namespace functor_to_types
variables {C : Type u} [category.{v} C] (F G H : C ⥤ Type w) {X Y Z : C}
variables (σ : F ⟶ G) (τ : G ⟶ H)
@[simp] lemma map_comp_apply (f : X ⟶ Y) (g : Y ⟶ Z) (a : F.obj X) :
(F.map (f ≫ g)) a = (F.map g) ((F.map f) a) :=
by simp [types_comp]
@[simp] lemma map_id_apply (a : F.obj X) : (F.map (𝟙 X)) a = a :=
by simp [types_id]
lemma naturality (f : X ⟶ Y) (x : F.obj X) : σ.app Y ((F.map f) x) = (G.map f) (σ.app X x) :=
congr_fun (σ.naturality f) x
@[simp] lemma comp (x : F.obj X) : (σ ≫ τ).app X x = τ.app X (σ.app X x) := rfl
variables {D : Type u'} [𝒟 : category.{u'} D] (I J : D ⥤ C) (ρ : I ⟶ J) {W : D}
@[simp] lemma hcomp (x : (I ⋙ F).obj W) :
(ρ ◫ σ).app W x = (G.map (ρ.app W)) (σ.app (I.obj W) x) :=
rfl
@[simp] lemma map_inv_map_hom_apply (f : X ≅ Y) (x : F.obj X) : F.map f.inv (F.map f.hom x) = x :=
congr_fun (F.map_iso f).hom_inv_id x
@[simp] lemma map_hom_map_inv_apply (f : X ≅ Y) (y : F.obj Y) : F.map f.hom (F.map f.inv y) = y :=
congr_fun (F.map_iso f).inv_hom_id y
@[simp] lemma hom_inv_id_app_apply (α : F ≅ G) (X) (x) : α.inv.app X (α.hom.app X x) = x :=
congr_fun (α.hom_inv_id_app X) x
@[simp] lemma inv_hom_id_app_apply (α : F ≅ G) (X) (x) : α.hom.app X (α.inv.app X x) = x :=
congr_fun (α.inv_hom_id_app X) x
end functor_to_types
/--
The isomorphism between a `Type` which has been `ulift`ed to the same universe,
and the original type.
-/
def ulift_trivial (V : Type u) : ulift.{u} V ≅ V := by tidy
/--
The functor embedding `Type u` into `Type (max u v)`.
Write this as `ulift_functor.{5 2}` to get `Type 2 ⥤ Type 5`.
-/
def ulift_functor : Type u ⥤ Type (max u v) :=
{ obj := λ X, ulift.{v} X,
map := λ X Y f, λ x : ulift.{v} X, ulift.up (f x.down) }
@[simp] lemma ulift_functor_map {X Y : Type u} (f : X ⟶ Y) (x : ulift.{v} X) :
ulift_functor.map f x = ulift.up (f x.down) := rfl
instance ulift_functor_full : full.{u} ulift_functor :=
{ preimage := λ X Y f x, (f (ulift.up x)).down }
instance ulift_functor_faithful : faithful ulift_functor :=
{ map_injective' := λ X Y f g p, funext $ λ x,
congr_arg ulift.down ((congr_fun p (ulift.up x)) : ((ulift.up (f x)) = (ulift.up (g x)))) }
/--
The functor embedding `Type u` into `Type u` via `ulift` is isomorphic to the identity functor.
-/
def ulift_functor_trivial : ulift_functor.{u u} ≅ 𝟭 _ :=
nat_iso.of_components ulift_trivial (by tidy)
/-- Any term `x` of a type `X` corresponds to a morphism `punit ⟶ X`. -/
-- TODO We should connect this to a general story about concrete categories
-- whose forgetful functor is representable.
def hom_of_element {X : Type u} (x : X) : punit ⟶ X := λ _, x
lemma hom_of_element_eq_iff {X : Type u} (x y : X) :
hom_of_element x = hom_of_element y ↔ x = y :=
⟨λ H, congr_fun H punit.star, by cc⟩
/--
A morphism in `Type` is a monomorphism if and only if it is injective.
See https://stacks.math.columbia.edu/tag/003C.
-/
lemma mono_iff_injective {X Y : Type u} (f : X ⟶ Y) : mono f ↔ function.injective f :=
begin
split,
{ intros H x x' h,
resetI,
rw ←hom_of_element_eq_iff at ⊢ h,
exact (cancel_mono f).mp h },
{ exact λ H, ⟨λ Z, H.comp_left⟩ }
end
/--
A morphism in `Type` is an epimorphism if and only if it is surjective.
See https://stacks.math.columbia.edu/tag/003C.
-/
lemma epi_iff_surjective {X Y : Type u} (f : X ⟶ Y) : epi f ↔ function.surjective f :=
begin
split,
{ rintros ⟨H⟩,
refine function.surjective_of_right_cancellable_Prop (λ g₁ g₂ hg, _),
rw [← equiv.ulift.symm.injective.comp_left.eq_iff],
apply H,
change ulift.up ∘ (g₁ ∘ f) = ulift.up ∘ (g₂ ∘ f),
rw hg },
{ exact λ H, ⟨λ Z, H.injective_comp_right⟩ }
end
section
/-- `of_type_functor m` converts from Lean's `Type`-based `category` to `category_theory`. This
allows us to use these functors in category theory. -/
def of_type_functor (m : Type u → Type v) [_root_.functor m] [is_lawful_functor m] :
Type u ⥤ Type v :=
{ obj := m,
map := λα β, _root_.functor.map,
map_id' := assume α, _root_.functor.map_id,
map_comp' := assume α β γ f g, funext $ assume a, is_lawful_functor.comp_map f g _ }
variables (m : Type u → Type v) [_root_.functor m] [is_lawful_functor m]
@[simp]
lemma of_type_functor_obj : (of_type_functor m).obj = m := rfl
@[simp]
lemma of_type_functor_map {α β} (f : α → β) :
(of_type_functor m).map f = (_root_.functor.map f : m α → m β) := rfl
end
end category_theory
-- Isomorphisms in Type and equivalences.
namespace equiv
universe u
variables {X Y : Type u}
/--
Any equivalence between types in the same universe gives
a categorical isomorphism between those types.
-/
def to_iso (e : X ≃ Y) : X ≅ Y :=
{ hom := e.to_fun,
inv := e.inv_fun,
hom_inv_id' := funext e.left_inv,
inv_hom_id' := funext e.right_inv }
@[simp] lemma to_iso_hom {e : X ≃ Y} : e.to_iso.hom = e := rfl
@[simp] lemma to_iso_inv {e : X ≃ Y} : e.to_iso.inv = e.symm := rfl
end equiv
universe u
namespace category_theory.iso
open category_theory
variables {X Y : Type u}
/--
Any isomorphism between types gives an equivalence.
-/
def to_equiv (i : X ≅ Y) : X ≃ Y :=
{ to_fun := i.hom,
inv_fun := i.inv,
left_inv := λ x, congr_fun i.hom_inv_id x,
right_inv := λ y, congr_fun i.inv_hom_id y }
@[simp] lemma to_equiv_fun (i : X ≅ Y) : (i.to_equiv : X → Y) = i.hom := rfl
@[simp] lemma to_equiv_symm_fun (i : X ≅ Y) : (i.to_equiv.symm : Y → X) = i.inv := rfl
@[simp] lemma to_equiv_id (X : Type u) : (iso.refl X).to_equiv = equiv.refl X := rfl
@[simp] lemma to_equiv_comp {X Y Z : Type u} (f : X ≅ Y) (g : Y ≅ Z) :
(f ≪≫ g).to_equiv = f.to_equiv.trans (g.to_equiv) := rfl
end category_theory.iso
namespace category_theory
/-- A morphism in `Type u` is an isomorphism if and only if it is bijective. -/
lemma is_iso_iff_bijective {X Y : Type u} (f : X ⟶ Y) : is_iso f ↔ function.bijective f :=
iff.intro
(λ i, (by exactI as_iso f : X ≅ Y).to_equiv.bijective)
(λ b, is_iso.of_iso (equiv.of_bijective f b).to_iso)
end category_theory
-- We prove `equiv_iso_iso` and then use that to sneakily construct `equiv_equiv_iso`.
-- (In this order the proofs are handled by `obviously`.)
/-- Equivalences (between types in the same universe) are the same as (isomorphic to) isomorphisms
of types. -/
@[simps] def equiv_iso_iso {X Y : Type u} : (X ≃ Y) ≅ (X ≅ Y) :=
{ hom := λ e, e.to_iso,
inv := λ i, i.to_equiv, }
/-- Equivalences (between types in the same universe) are the same as (equivalent to) isomorphisms
of types. -/
def equiv_equiv_iso {X Y : Type u} : (X ≃ Y) ≃ (X ≅ Y) :=
(equiv_iso_iso).to_equiv
@[simp] lemma equiv_equiv_iso_hom {X Y : Type u} (e : X ≃ Y) :
equiv_equiv_iso e = e.to_iso := rfl
@[simp] lemma equiv_equiv_iso_inv {X Y : Type u} (e : X ≅ Y) :
equiv_equiv_iso.symm e = e.to_equiv := rfl
|
7287a13b108c5bd37556cf6989361411e0b4b79c | 07c76fbd96ea1786cc6392fa834be62643cea420 | /hott/cubical/pathover2.hlean | 5546aa6c7b3d670b44e673462f09d1859d02af4c | [
"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 | 8,050 | 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
Coherence conditions for operations on pathovers
-/
open function equiv
namespace eq
variables {A A' A'' : Type} {B B' : A → Type} {B'' : A' → Type} {C : Π⦃a⦄, B a → Type}
{a a₂ a₃ a₄ : A} {p p' p'' : a = a₂} {p₂ p₂' : a₂ = a₃} {p₃ : a₃ = a₄} {p₁₃ : a = a₃}
{a' : A'}
{b b' : B a} {b₂ b₂' : B a₂} {b₃ : B a₃} {b₄ : B a₄}
{c : C b} {c₂ : C b₂}
definition pathover_ap_id (q : b =[p] b₂) : pathover_ap B id q = change_path (ap_id p)⁻¹ q :=
by induction q; reflexivity
definition pathover_ap_compose (B : A'' → Type) (g : A' → A'') (f : A → A')
{b : B (g (f a))} {b₂ : B (g (f a₂))} (q : b =[p] b₂) : pathover_ap B (g ∘ f) q
= change_path (ap_compose g f p)⁻¹ (pathover_ap B g (pathover_ap (B ∘ g) f q)) :=
by induction q; reflexivity
definition pathover_ap_compose_rev (B : A'' → Type) (g : A' → A'') (f : A → A')
{b : B (g (f a))} {b₂ : B (g (f a₂))} (q : b =[p] b₂) :
pathover_ap B g (pathover_ap (B ∘ g) f q)
= change_path (ap_compose g f p) (pathover_ap B (g ∘ f) q) :=
by induction q; reflexivity
definition pathover_idp_of_eq_def (r : b = b') : pathover_of_tr_eq r = pathover_idp_of_eq r :=
idp
definition pathover_of_tr_eq_eq_concato (r : p ▸ b = b₂)
: pathover_of_tr_eq r = pathover_tr p b ⬝o pathover_idp_of_eq r :=
by induction r; induction p; reflexivity
definition apd011_eq_apo11_apd (f : Πa, B a → A') (p : a = a₂) (q : b =[p] b₂)
: apd011 f p q = apo11_constant_right (apd f p) q :=
by induction q; reflexivity
definition change_path_con (q : p = p') (q' : p' = p'') (r : b =[p] b₂) :
change_path (q ⬝ q') r = change_path q' (change_path q r) :=
by induction q; induction q'; reflexivity
definition change_path_invo (q : p = p') (r : b =[p] b₂) :
change_path (inverse2 q) r⁻¹ᵒ = (change_path q r)⁻¹ᵒ :=
by induction q; reflexivity
definition change_path_cono (q : p = p') (q₂ : p₂ = p₂') (r : b =[p] b₂) (r₂ : b₂ =[p₂] b₃):
change_path (q ◾ q₂) (r ⬝o r₂) = change_path q r ⬝o change_path q₂ r₂ :=
by induction q; induction q₂; reflexivity
definition pathover_of_pathover_ap_invo (B' : A' → Type) (f : A → A')
{b : B' (f a)} {b₂ : B' (f a₂)} (q : b =[ap f p] b₂) :
pathover_of_pathover_ap B' f (change_path (ap_inv f p)⁻¹ q⁻¹ᵒ) =
(pathover_of_pathover_ap B' f q)⁻¹ᵒ:=
by induction p; eapply idp_rec_on q; reflexivity
definition pathover_of_pathover_ap_cono (B' : A' → Type) (f : A → A')
{b : B' (f a)} {b₂ : B' (f a₂)} {b₃ : B' (f a₃)} (q : b =[ap f p] b₂) (q₂ : b₂ =[ap f p₂] b₃) :
pathover_of_pathover_ap B' f (change_path (ap_con f p p₂)⁻¹ (q ⬝o q₂)) =
pathover_of_pathover_ap B' f q ⬝o pathover_of_pathover_ap B' f q₂ :=
by induction p; induction p₂; eapply idp_rec_on q; eapply idp_rec_on q₂; reflexivity
definition pathover_ap_pathover_of_pathover_ap (P : A'' → Type) (g : A' → A'') (f : A → A')
{p : a = a₂} {b : P (g (f a))} {b₂ : P (g (f a₂))} (q : b =[ap f p] b₂) :
pathover_ap P (g ∘ f) (pathover_of_pathover_ap (P ∘ g) f q) =
change_path (ap_compose g f p)⁻¹ (pathover_ap P g q) :=
by induction p; eapply (idp_rec_on q); reflexivity
definition change_path_pathover_of_pathover_ap (B' : A' → Type) (f : A → A') {p p' : a = a₂}
(r : p = p') {b : B' (f a)} {b₂ : B' (f a₂)} (q : b =[ap f p] b₂) :
change_path r (pathover_of_pathover_ap B' f q) =
pathover_of_pathover_ap B' f (change_path (ap02 f r) q) :=
by induction r; reflexivity
definition pathover_ap_change_path (B' : A' → Type) (f : A → A') {p p' : a = a₂}
(r : p = p') {b : B' (f a)} {b₂ : B' (f a₂)} (q : b =[p] b₂) :
pathover_ap B' f (change_path r q) = change_path (ap02 f r) (pathover_ap B' f q) :=
by induction r; reflexivity
definition change_path_equiv [constructor] (b : B a) (b₂ : B a₂) (q : p = p')
: (b =[p] b₂) ≃ (b =[p'] b₂) :=
begin
fapply equiv.MK,
{ exact change_path q},
{ exact change_path q⁻¹},
{ intro r, induction q, reflexivity},
{ intro r, induction q, reflexivity},
end
definition apd_ap {B : A' → Type} (g : Πb, B b) (f : A → A') (p : a = a₂)
: apd g (ap f p) = pathover_ap B f (apd (λx, g (f x)) p) :=
by induction p; reflexivity
definition apd_eq_apd_ap {B : A' → Type} (g : Πb, B b) (f : A → A') (p : a = a₂)
: apd (λx, g (f x)) p = pathover_of_pathover_ap B f (apd g (ap f p)) :=
by induction p; reflexivity
definition ap_compose_ap02_constant {A B C : Type} {a a' : A} (p : a = a') (b : B) (c : C) :
ap_compose (λc, b) (λa, c) p ⬝ ap02 (λc, b) (ap_constant p c) = ap_constant p b :=
by induction p; reflexivity
theorem apd_constant (b : B'' a') (p : a = a) :
pathover_ap B'' (λa, a') (apd (λa, b) p) = change_path (ap_constant p a')⁻¹ idpo :=
begin
rewrite [apd_eq_apd_ap _ _ p],
let y := !change_path_of_pathover (apd (apd id) (ap_constant p b))⁻¹ᵒ,
rewrite -y, esimp,
refine !pathover_ap_pathover_of_pathover_ap ⬝ _,
rewrite pathover_ap_change_path,
rewrite -change_path_con, apply ap (λx, change_path x idpo),
unfold ap02, rewrite [ap_inv,-con_inv], apply inverse2,
apply ap_compose_ap02_constant
end
theorem apd_constant' {A A' : Type} {B : A' → Type} {a₁ a₂ : A} {a' : A'} (b : B a')
(p : a₁ = a₂) : apd (λx, b) p = pathover_of_eq p idp :=
by induction p; reflexivity
definition apd_change_path {B : A → Type} {a a₂ : A} (f : Πa, B a) {p p' : a = a₂} (s : p = p')
: apd f p' = change_path s (apd f p) :=
by induction s; reflexivity
definition cono_invo_eq_idpo {q q' : b =[p] b₂} (r : q = q')
: change_path (con.right_inv p) (q ⬝o q'⁻¹ᵒ) = idpo :=
by induction r; induction q; reflexivity
definition tr_eq_of_pathover_concato_eq {A : Type} {B : A → Type} {a a' : A} {p : a = a'}
{b : B a} {b' b'' : B a'} (q : b =[p] b') (r : b' = b'') :
tr_eq_of_pathover (q ⬝op r) = tr_eq_of_pathover q ⬝ r :=
by induction r; reflexivity
definition pathover_tr_pathover_idp_of_eq {A : Type} {B : A → Type} {a a' : A} {b : B a} {b' : B a'} {p : a = a'}
(q : b =[p] b') :
pathover_tr p b ⬝o pathover_idp_of_eq (tr_eq_of_pathover q) = q :=
begin induction q; reflexivity end
definition pathover_of_tr_eq_idp' {A : Type} {B : A → Type} {a a₂ : A} (p : a = a₂) (b : B a) :
pathover_of_tr_eq idp = pathover_tr p b :=
by induction p; constructor
definition eq_of_pathover_apo {A C : Type} {B : A → Type} {a a' : A} {b : B a} {b' : B a'}
{p : a = a'} (g : Πa, B a → C) (q : b =[p] b') :
eq_of_pathover (apo g q) = apd011 g p q :=
by induction q; reflexivity
definition pathover_ap_cono {A A' : Type} {a₁ a₂ a₃ : A}
{p₁ : a₁ = a₂} {p₂ : a₂ = a₃} (B' : A' → Type) (f : A → A')
{b₁ : B' (f a₁)} {b₂ : B' (f a₂)} {b₃ : B' (f a₃)}
(q₁ : b₁ =[p₁] b₂) (q₂ : b₂ =[p₂] b₃) :
pathover_ap B' f (q₁ ⬝o q₂) =
change_path !ap_con⁻¹ (pathover_ap B' f q₁ ⬝o pathover_ap B' f q₂) :=
by induction q₁; induction q₂; reflexivity
definition concato_eq_eq {A : Type} {B : A → Type} {a₁ a₂ : A} {p₁ : a₁ = a₂}
{b₁ : B a₁} {b₂ b₂' : B a₂} (r : b₁ =[p₁] b₂) (q : b₂ = b₂') :
r ⬝op q = r ⬝o pathover_idp_of_eq q :=
by induction q; reflexivity
definition eq_tr_of_pathover_con_tr_eq_of_pathover {A : Type} {B : A → Type}
{a₁ a₂ : A} (p : a₁ = a₂) {b₁ : B a₁} {b₂ : B a₂} (q : b₁ =[p] b₂) :
eq_tr_of_pathover q ⬝ tr_eq_of_pathover q⁻¹ᵒ = idp :=
by induction q; reflexivity
end eq
|
8c68eb69305722a1c86bfdf936749bbef2595bd8 | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/analysis/special_functions/trigonometric/arctan.lean | 1b00d5a47d1b4f22c35c95a16c21be7cbfa4093a | [
"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 | 8,079 | lean | /-
Copyright (c) 2018 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes, Abhimanyu Pallavi Sudhir, Jean Lo, Calle Sönne, Benjamin Davidson
-/
import analysis.special_functions.trigonometric.complex
/-!
# The `arctan` function.
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
Inequalities, derivatives,
and `real.tan` as a `local_homeomorph` between `(-(π / 2), π / 2)` and the whole line.
-/
noncomputable theory
namespace real
open set filter
open_locale topology real
lemma tan_add {x y : ℝ}
(h : ((∀ k : ℤ, x ≠ (2 * k + 1) * π / 2) ∧ ∀ l : ℤ, y ≠ (2 * l + 1) * π / 2)
∨ ((∃ k : ℤ, x = (2 * k + 1) * π / 2) ∧ ∃ l : ℤ, y = (2 * l + 1) * π / 2)) :
tan (x + y) = (tan x + tan y) / (1 - tan x * tan y) :=
by simpa only [← complex.of_real_inj, complex.of_real_sub, complex.of_real_add, complex.of_real_div,
complex.of_real_mul, complex.of_real_tan]
using @complex.tan_add (x:ℂ) (y:ℂ) (by convert h; norm_cast)
lemma tan_add' {x y : ℝ}
(h : ((∀ k : ℤ, x ≠ (2 * k + 1) * π / 2) ∧ ∀ l : ℤ, y ≠ (2 * l + 1) * π / 2)) :
tan (x + y) = (tan x + tan y) / (1 - tan x * tan y) :=
tan_add (or.inl h)
lemma tan_two_mul {x:ℝ} : tan (2 * x) = 2 * tan x / (1 - tan x ^ 2) :=
by simpa only [← complex.of_real_inj, complex.of_real_sub, complex.of_real_div, complex.of_real_pow,
complex.of_real_mul, complex.of_real_tan, complex.of_real_bit0, complex.of_real_one]
using complex.tan_two_mul
lemma tan_ne_zero_iff {θ : ℝ} : tan θ ≠ 0 ↔ ∀ k : ℤ, θ ≠ k * π / 2 :=
by rw [← complex.of_real_ne_zero, complex.of_real_tan, complex.tan_ne_zero_iff]; norm_cast
lemma tan_eq_zero_iff {θ : ℝ} : tan θ = 0 ↔ ∃ k : ℤ, θ = k * π / 2 :=
by rw [← not_iff_not, not_exists, ← ne, tan_ne_zero_iff]
lemma tan_int_mul_pi_div_two (n : ℤ) : tan (n * π/2) = 0 :=
tan_eq_zero_iff.mpr (by use n)
lemma continuous_on_tan : continuous_on tan {x | cos x ≠ 0} :=
begin
suffices : continuous_on (λ x, sin x / cos x) {x | cos x ≠ 0},
{ have h_eq : (λ x, sin x / cos x) = tan, by {ext1 x, rw tan_eq_sin_div_cos, },
rwa h_eq at this, },
exact continuous_on_sin.div continuous_on_cos (λ x, id),
end
@[continuity]
lemma continuous_tan : continuous (λ x : {x | cos x ≠ 0}, tan x) :=
continuous_on_iff_continuous_restrict.1 continuous_on_tan
lemma continuous_on_tan_Ioo : continuous_on tan (Ioo (-(π/2)) (π/2)) :=
begin
refine continuous_on.mono continuous_on_tan (λ x, _),
simp only [and_imp, mem_Ioo, mem_set_of_eq, ne.def],
rw cos_eq_zero_iff,
rintros hx_gt hx_lt ⟨r, hxr_eq⟩,
cases le_or_lt 0 r,
{ rw lt_iff_not_ge at hx_lt,
refine hx_lt _,
rw [hxr_eq, ← one_mul (π / 2), mul_div_assoc, ge_iff_le, mul_le_mul_right (half_pos pi_pos)],
simp [h], },
{ rw lt_iff_not_ge at hx_gt,
refine hx_gt _,
rw [hxr_eq, ← one_mul (π / 2), mul_div_assoc, ge_iff_le, neg_mul_eq_neg_mul,
mul_le_mul_right (half_pos pi_pos)],
have hr_le : r ≤ -1, by rwa [int.lt_iff_add_one_le, ← le_neg_iff_add_nonpos_right] at h,
rw [← le_sub_iff_add_le, mul_comm, ← le_div_iff],
{ norm_num, rw [← int.cast_one, ← int.cast_neg], norm_cast, exact hr_le, },
{ exact zero_lt_two, }, },
end
lemma surj_on_tan : surj_on tan (Ioo (-(π / 2)) (π / 2)) univ :=
have _ := neg_lt_self pi_div_two_pos,
continuous_on_tan_Ioo.surj_on_of_tendsto (nonempty_Ioo.2 this)
(by simp [tendsto_tan_neg_pi_div_two, this]) (by simp [tendsto_tan_pi_div_two, this])
lemma tan_surjective : function.surjective tan :=
λ x, surj_on_tan.subset_range trivial
lemma image_tan_Ioo : tan '' (Ioo (-(π / 2)) (π / 2)) = univ :=
univ_subset_iff.1 surj_on_tan
/-- `real.tan` as an `order_iso` between `(-(π / 2), π / 2)` and `ℝ`. -/
def tan_order_iso : Ioo (-(π / 2)) (π / 2) ≃o ℝ :=
(strict_mono_on_tan.order_iso _ _).trans $ (order_iso.set_congr _ _ image_tan_Ioo).trans
order_iso.set.univ
/-- Inverse of the `tan` function, returns values in the range `-π / 2 < arctan x` and
`arctan x < π / 2` -/
@[pp_nodot] noncomputable def arctan (x : ℝ) : ℝ :=
tan_order_iso.symm x
@[simp] lemma tan_arctan (x : ℝ) : tan (arctan x) = x :=
tan_order_iso.apply_symm_apply x
lemma arctan_mem_Ioo (x : ℝ) : arctan x ∈ Ioo (-(π / 2)) (π / 2) :=
subtype.coe_prop _
@[simp] lemma range_arctan : range arctan = Ioo (-(π / 2)) (π / 2) :=
((equiv_like.surjective _).range_comp _).trans subtype.range_coe
lemma arctan_tan {x : ℝ} (hx₁ : -(π / 2) < x) (hx₂ : x < π / 2) : arctan (tan x) = x :=
subtype.ext_iff.1 $ tan_order_iso.symm_apply_apply ⟨x, hx₁, hx₂⟩
lemma cos_arctan_pos (x : ℝ) : 0 < cos (arctan x) :=
cos_pos_of_mem_Ioo $ arctan_mem_Ioo x
lemma cos_sq_arctan (x : ℝ) : cos (arctan x) ^ 2 = 1 / (1 + x ^ 2) :=
by rw [one_div, ← inv_one_add_tan_sq (cos_arctan_pos x).ne', tan_arctan]
lemma sin_arctan (x : ℝ) : sin (arctan x) = x / sqrt (1 + x ^ 2) :=
by rw [← tan_div_sqrt_one_add_tan_sq (cos_arctan_pos x), tan_arctan]
lemma cos_arctan (x : ℝ) : cos (arctan x) = 1 / sqrt (1 + x ^ 2) :=
by rw [one_div, ← inv_sqrt_one_add_tan_sq (cos_arctan_pos x), tan_arctan]
lemma arctan_lt_pi_div_two (x : ℝ) : arctan x < π / 2 :=
(arctan_mem_Ioo x).2
lemma neg_pi_div_two_lt_arctan (x : ℝ) : -(π / 2) < arctan x :=
(arctan_mem_Ioo x).1
lemma arctan_eq_arcsin (x : ℝ) : arctan x = arcsin (x / sqrt (1 + x ^ 2)) :=
eq.symm $ arcsin_eq_of_sin_eq (sin_arctan x) (mem_Icc_of_Ioo $ arctan_mem_Ioo x)
lemma arcsin_eq_arctan {x : ℝ} (h : x ∈ Ioo (-(1:ℝ)) 1) :
arcsin x = arctan (x / sqrt (1 - x ^ 2)) :=
begin
rw [arctan_eq_arcsin, div_pow, sq_sqrt, one_add_div, div_div,
← sqrt_mul, mul_div_cancel', sub_add_cancel, sqrt_one, div_one];
nlinarith [h.1, h.2],
end
@[simp] lemma arctan_zero : arctan 0 = 0 :=
by simp [arctan_eq_arcsin]
lemma arctan_eq_of_tan_eq {x y : ℝ} (h : tan x = y) (hx : x ∈ Ioo (-(π / 2)) (π / 2)) :
arctan y = x :=
inj_on_tan (arctan_mem_Ioo _) hx (by rw [tan_arctan, h])
@[simp] lemma arctan_one : arctan 1 = π / 4 :=
arctan_eq_of_tan_eq tan_pi_div_four $ by split; linarith [pi_pos]
@[simp] lemma arctan_neg (x : ℝ) : arctan (-x) = - arctan x :=
by simp [arctan_eq_arcsin, neg_div]
lemma arctan_eq_arccos {x : ℝ} (h : 0 ≤ x) : arctan x = arccos ((sqrt (1 + x ^ 2))⁻¹) :=
begin
rw [arctan_eq_arcsin, arccos_eq_arcsin], swap, { exact inv_nonneg.2 (sqrt_nonneg _) },
congr' 1,
rw [←sqrt_inv, sq_sqrt, ←one_div, one_sub_div, add_sub_cancel', sqrt_div, sqrt_sq h],
all_goals { positivity }
end
-- The junk values for `arccos` and `sqrt` make this true even for `1 < x`.
lemma arccos_eq_arctan {x : ℝ} (h : 0 < x) :
arccos x = arctan (sqrt (1 - x ^ 2) / x) :=
begin
rw [arccos, eq_comm],
refine arctan_eq_of_tan_eq _ ⟨_, _⟩,
{ rw [tan_pi_div_two_sub, tan_arcsin, inv_div] },
{ linarith only [arcsin_le_pi_div_two x, pi_pos] },
{ linarith only [arcsin_pos.2 h] }
end
@[continuity]
lemma continuous_arctan : continuous arctan :=
continuous_subtype_coe.comp tan_order_iso.to_homeomorph.continuous_inv_fun
lemma continuous_at_arctan {x : ℝ} : continuous_at arctan x := continuous_arctan.continuous_at
/-- `real.tan` as a `local_homeomorph` between `(-(π / 2), π / 2)` and the whole line. -/
def tan_local_homeomorph : local_homeomorph ℝ ℝ :=
{ to_fun := tan,
inv_fun := arctan,
source := Ioo (-(π / 2)) (π / 2),
target := univ,
map_source' := maps_to_univ _ _,
map_target' := λ y hy, arctan_mem_Ioo y,
left_inv' := λ x hx, arctan_tan hx.1 hx.2,
right_inv' := λ y hy, tan_arctan y,
open_source := is_open_Ioo,
open_target := is_open_univ,
continuous_to_fun := continuous_on_tan_Ioo,
continuous_inv_fun := continuous_arctan.continuous_on }
@[simp] lemma coe_tan_local_homeomorph : ⇑tan_local_homeomorph = tan := rfl
@[simp] lemma coe_tan_local_homeomorph_symm : ⇑tan_local_homeomorph.symm = arctan := rfl
end real
|
20bb713f2eb9b12e645bc886b73a484f3b6eef73 | 94e33a31faa76775069b071adea97e86e218a8ee | /src/linear_algebra/quadratic_form/real.lean | 506ee8226d9c6cb466f1258604be15f8f1ae5ec4 | [
"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 | 4,357 | lean | /-
Copyright (c) 2020 Anne Baanen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Anne Baanen, Kexing Ying, Eric Wieser
-/
import linear_algebra.quadratic_form.isometry
import analysis.special_functions.pow
import data.real.sign
/-!
# Real quadratic forms
Sylvester's law of inertia `equivalent_one_neg_one_weighted_sum_squared`:
A real quadratic form is equivalent to a weighted
sum of squares with the weights being ±1 or 0.
When the real quadratic form is nondegerate we can take the weights to be ±1,
as in `equivalent_one_zero_neg_one_weighted_sum_squared`.
-/
namespace quadratic_form
open_locale big_operators
open real finset
variables {ι : Type*} [fintype ι]
/-- The isometry between a weighted sum of squares with weights `u` on the
(non-zero) real numbers and the weighted sum of squares with weights `sign ∘ u`. -/
noncomputable def isometry_sign_weighted_sum_squares
[decidable_eq ι] (w : ι → ℝ) :
isometry (weighted_sum_squares ℝ w) (weighted_sum_squares ℝ (sign ∘ w)) :=
begin
let u := λ i, if h : w i = 0 then (1 : ℝˣ) else units.mk0 (w i) h,
have hu' : ∀ i : ι, (sign (u i) * u i) ^ - (1 / 2 : ℝ) ≠ 0,
{ intro i, refine (ne_of_lt (real.rpow_pos_of_pos
(sign_mul_pos_of_ne_zero _ $ units.ne_zero _) _)).symm},
convert ((weighted_sum_squares ℝ w).isometry_basis_repr
((pi.basis_fun ℝ ι).units_smul (λ i, (is_unit_iff_ne_zero.2 $ hu' i).unit))),
ext1 v,
rw [basis_repr_apply, weighted_sum_squares_apply, weighted_sum_squares_apply],
refine sum_congr rfl (λ j hj, _),
have hsum : (∑ (i : ι), v i • ((is_unit_iff_ne_zero.2 $ hu' i).unit : ℝ) •
(pi.basis_fun ℝ ι) i) j = v j • (sign (u j) * u j) ^ - (1 / 2 : ℝ),
{ rw [finset.sum_apply, sum_eq_single j, pi.basis_fun_apply, is_unit.unit_spec,
linear_map.std_basis_apply, pi.smul_apply, pi.smul_apply, function.update_same,
smul_eq_mul, smul_eq_mul, smul_eq_mul, mul_one],
intros i _ hij,
rw [pi.basis_fun_apply, linear_map.std_basis_apply, pi.smul_apply, pi.smul_apply,
function.update_noteq hij.symm, pi.zero_apply, smul_eq_mul, smul_eq_mul,
mul_zero, mul_zero],
intro hj', exact false.elim (hj' hj) },
simp_rw basis.units_smul_apply,
erw [hsum],
simp only [u, function.comp, smul_eq_mul],
split_ifs,
{ simp only [h, zero_smul, zero_mul, sign_zero] },
have hwu : w j = u j,
{ simp only [u, dif_neg h, units.coe_mk0] },
simp only [hwu, units.coe_mk0],
suffices : (u j : ℝ).sign * v j * v j = (sign (u j) * u j) ^ - (1 / 2 : ℝ) *
(sign (u j) * u j) ^ - (1 / 2 : ℝ) * u j * v j * v j,
{ erw [← mul_assoc, this], ring },
rw [← real.rpow_add (sign_mul_pos_of_ne_zero _ $ units.ne_zero _),
show - (1 / 2 : ℝ) + - (1 / 2) = -1, by ring, real.rpow_neg_one, mul_inv,
inv_sign, mul_assoc (sign (u j)) (u j)⁻¹,
inv_mul_cancel (units.ne_zero _), mul_one],
apply_instance
end
/-- **Sylvester's law of inertia**: A nondegenerate real quadratic form is equivalent to a weighted
sum of squares with the weights being ±1. -/
theorem equivalent_one_neg_one_weighted_sum_squared
{M : Type*} [add_comm_group M] [module ℝ M] [finite_dimensional ℝ M]
(Q : quadratic_form ℝ M) (hQ : (associated Q).nondegenerate) :
∃ w : fin (finite_dimensional.finrank ℝ M) → ℝ,
(∀ i, w i = -1 ∨ w i = 1) ∧ equivalent Q (weighted_sum_squares ℝ w) :=
let ⟨w, ⟨hw₁⟩⟩ := Q.equivalent_weighted_sum_squares_units_of_nondegenerate' hQ in
⟨sign ∘ coe ∘ w,
λ i, sign_apply_eq_of_ne_zero (w i) (w i).ne_zero,
⟨hw₁.trans (isometry_sign_weighted_sum_squares (coe ∘ w))⟩⟩
/-- **Sylvester's law of inertia**: A real quadratic form is equivalent to a weighted
sum of squares with the weights being ±1 or 0. -/
theorem equivalent_one_zero_neg_one_weighted_sum_squared
{M : Type*} [add_comm_group M] [module ℝ M] [finite_dimensional ℝ M]
(Q : quadratic_form ℝ M) :
∃ w : fin (finite_dimensional.finrank ℝ M) → ℝ,
(∀ i, w i = -1 ∨ w i = 0 ∨ w i = 1) ∧ equivalent Q (weighted_sum_squares ℝ w) :=
let ⟨w, ⟨hw₁⟩⟩ := Q.equivalent_weighted_sum_squares in
⟨sign ∘ coe ∘ w,
λ i, sign_apply_eq (w i),
⟨hw₁.trans (isometry_sign_weighted_sum_squares w)⟩⟩
end quadratic_form
|
1bc03d9d12b7d4bae42b2071a66964ccc596671d | 649957717d58c43b5d8d200da34bf374293fe739 | /src/tactic/core.lean | 1e73b5cb7aa3416b2f504ce2509fcce2c79a5500 | [
"Apache-2.0"
] | permissive | Vtec234/mathlib | b50c7b21edea438df7497e5ed6a45f61527f0370 | fb1848bbbfce46152f58e219dc0712f3289d2b20 | refs/heads/master | 1,592,463,095,113 | 1,562,737,749,000 | 1,562,737,749,000 | 196,202,858 | 0 | 0 | Apache-2.0 | 1,562,762,338,000 | 1,562,762,337,000 | null | UTF-8 | Lean | false | false | 37,111 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro, Simon Hudon, Scott Morrison, Keeley Hoek
-/
import data.dlist.basic category.basic meta.expr meta.rb_map tactic.cache
namespace expr
open tactic
attribute [derive has_reflect] binder_info
protected meta def of_nat (α : expr) : ℕ → tactic expr :=
nat.binary_rec
(tactic.mk_mapp ``has_zero.zero [some α, none])
(λ b n tac, if n = 0 then mk_mapp ``has_one.one [some α, none] else
do e ← tac, tactic.mk_app (cond b ``bit1 ``bit0) [e])
protected meta def of_int (α : expr) : ℤ → tactic expr
| (n : ℕ) := expr.of_nat α n
| -[1+ n] := do
e ← expr.of_nat α (n+1),
tactic.mk_app ``has_neg.neg [e]
/- only traverses the direct descendents -/
meta def {u} traverse {m : Type → Type u} [applicative m]
{elab elab' : bool} (f : expr elab → m (expr elab')) :
expr elab → m (expr elab')
| (var v) := pure $ var v
| (sort l) := pure $ sort l
| (const n ls) := pure $ const n ls
| (mvar n n' e) := mvar n n' <$> f e
| (local_const n n' bi e) := local_const n n' bi <$> f e
| (app e₀ e₁) := app <$> f e₀ <*> f e₁
| (lam n bi e₀ e₁) := lam n bi <$> f e₀ <*> f e₁
| (pi n bi e₀ e₁) := pi n bi <$> f e₀ <*> f e₁
| (elet n e₀ e₁ e₂) := elet n <$> f e₀ <*> f e₁ <*> f e₂
| (macro mac es) := macro mac <$> list.traverse f es
meta def mfoldl {α : Type} {m} [monad m] (f : α → expr → m α) : α → expr → m α
| x e := prod.snd <$> (state_t.run (e.traverse $ λ e',
(get >>= monad_lift ∘ flip f e' >>= put) $> e') x : m _)
end expr
namespace interaction_monad
open result
meta def get_result {σ α} (tac : interaction_monad σ α) :
interaction_monad σ (interaction_monad.result σ α) | s :=
match tac s with
| r@(success _ s') := success r s'
| r@(exception _ _ s') := success r s'
end
end interaction_monad
namespace lean.parser
open lean interaction_monad.result
meta def of_tactic' {α} (tac : tactic α) : parser α :=
do r ← of_tactic (interaction_monad.get_result tac),
match r with
| (success a _) := return a
| (exception f pos _) := exception f pos
end
-- Override the builtin `lean.parser.of_tactic` coe, which is broken.
-- (See test/tactics.lean for a failure case.)
@[priority 2000]
meta instance has_coe' {α} : has_coe (tactic α) (parser α) :=
⟨of_tactic'⟩
meta def emit_command_here (str : string) : lean.parser string :=
do (_, left) ← with_input command_like str,
return left
-- Emit a source code string at the location being parsed.
meta def emit_code_here : string → lean.parser unit
| str := do left ← emit_command_here str,
if left.length = 0 then return ()
else emit_code_here left
end lean.parser
namespace name
meta def head : name → string
| (mk_string s anonymous) := s
| (mk_string s p) := head p
| (mk_numeral n p) := head p
| anonymous := "[anonymous]"
meta def is_private (n : name) : bool :=
n.head = "_private"
meta def last : name → string
| (mk_string s _) := s
| (mk_numeral n _) := repr n
| anonymous := "[anonymous]"
meta def length : name → ℕ
| (mk_string s anonymous) := s.length
| (mk_string s p) := s.length + 1 + p.length
| (mk_numeral n p) := p.length
| anonymous := "[anonymous]".length
end name
namespace environment
meta def decl_filter_map {α : Type} (e : environment) (f : declaration → option α) : list α :=
e.fold [] $ λ d l, match f d with
| some r := r :: l
| none := l
end
meta def decl_map {α : Type} (e : environment) (f : declaration → α) : list α :=
e.decl_filter_map $ λ d, some (f d)
meta def get_decls (e : environment) : list declaration :=
e.decl_map id
meta def get_trusted_decls (e : environment) : list declaration :=
e.decl_filter_map (λ d, if d.is_trusted then some d else none)
meta def get_decl_names (e : environment) : list name :=
e.decl_map declaration.to_name
end environment
namespace format
meta def intercalate (x : format) : list format → format :=
format.join ∘ list.intersperse x
end format
namespace tactic
meta def eval_expr' (α : Type*) [_inst_1 : reflected α] (e : expr) : tactic α :=
mk_app ``id [e] >>= eval_expr α
-- `mk_fresh_name` returns identifiers starting with underscores,
-- which are not legal when emitted by tactic programs. Turn the
-- useful source of random names provided by `mk_fresh_name` into
-- names which are usable by tactic programs.
--
-- The returned name has four components which are all strings.
meta def mk_user_fresh_name : tactic name :=
do nm ← mk_fresh_name,
return $ `user__ ++ nm.pop_prefix.sanitize_name ++ `user__
meta def is_simp_lemma : name → tactic bool :=
succeeds ∘ tactic.has_attribute `simp
meta def local_decls : tactic (name_map declaration) :=
do e ← tactic.get_env,
let xs := e.fold native.mk_rb_map
(λ d s, if environment.in_current_file' e d.to_name
then s.insert d.to_name d else s),
pure xs
/--
Returns a pair (e, t), where `e ← mk_const d.to_name`, and `t = d.type`
but with universe params updated to match the fresh universe metavariables in `e`.
This should have the same effect as just
```
do e ← mk_const d.to_name,
t ← infer_type e,
return (e, t)
```
but is hopefully faster.
-/
meta def decl_mk_const (d : declaration) : tactic (expr × expr) :=
do subst ← d.univ_params.mmap $ λ u, prod.mk u <$> mk_meta_univ,
let e : expr := expr.const d.to_name (prod.snd <$> subst),
return (e, d.type.instantiate_univ_params subst)
meta def simp_lemmas_from_file : tactic name_set :=
do s ← local_decls,
let s := s.map (expr.list_constant ∘ declaration.value),
xs ← s.to_list.mmap ((<$>) name_set.of_list ∘ mfilter tactic.is_simp_lemma ∘ name_set.to_list ∘ prod.snd),
return $ name_set.filter (λ x, ¬ s.contains x) (xs.foldl name_set.union mk_name_set)
meta def file_simp_attribute_decl (attr : name) : tactic unit :=
do s ← simp_lemmas_from_file,
trace format!"run_cmd mk_simp_attr `{attr}",
let lmms := format.join $ list.intersperse " " $ s.to_list.map to_fmt,
trace format!"local attribute [{attr}] {lmms}"
meta def mk_local (n : name) : expr :=
expr.local_const n n binder_info.default (expr.const n [])
meta def local_def_value (e : expr) : tactic expr := do
do (v,_) ← solve_aux `(true) (do
(expr.elet n t v _) ← (revert e >> target)
| fail format!"{e} is not a local definition",
return v),
return v
meta def check_defn (n : name) (e : pexpr) : tactic unit :=
do (declaration.defn _ _ _ d _ _) ← get_decl n,
e' ← to_expr e,
guard (d =ₐ e') <|> trace d >> failed
-- meta def compile_eqn (n : name) (univ : list name) (args : list expr) (val : expr) (num : ℕ) : tactic unit :=
-- do let lhs := (expr.const n $ univ.map level.param).mk_app args,
-- stmt ← mk_app `eq [lhs,val],
-- let vs := stmt.list_local_const,
-- let stmt := stmt.pis vs,
-- (_,pr) ← solve_aux stmt (tactic.intros >> reflexivity),
-- add_decl $ declaration.thm (n <.> "equations" <.> to_string (format!"_eqn_{num}")) univ stmt (pure pr)
meta def to_implicit : expr → expr
| (expr.local_const uniq n bi t) := expr.local_const uniq n binder_info.implicit t
| e := e
meta def pis : list expr → expr → tactic expr
| (e@(expr.local_const uniq pp info _) :: es) f := do
t ← infer_type e,
f' ← pis es f,
pure $ expr.pi pp info t (expr.abstract_local f' uniq)
| _ f := pure f
meta def lambdas : list expr → expr → tactic expr
| (e@(expr.local_const uniq pp info _) :: es) f := do
t ← infer_type e,
f' ← lambdas es f,
pure $ expr.lam pp info t (expr.abstract_local f' uniq)
| _ f := pure f
meta def extract_def (n : name) (trusted : bool) (elab_def : tactic unit) : tactic unit :=
do cxt ← list.map to_implicit <$> local_context,
t ← target,
(eqns,d) ← solve_aux t elab_def,
d ← instantiate_mvars d,
t' ← pis cxt t,
d' ← lambdas cxt d,
let univ := t'.collect_univ_params,
add_decl $ declaration.defn n univ t' d' (reducibility_hints.regular 1 tt) trusted,
applyc n
meta def exact_dec_trivial : tactic unit := `[exact dec_trivial]
/-- Runs a tactic for a result, reverting the state after completion -/
meta def retrieve {α} (tac : tactic α) : tactic α :=
λ s, result.cases_on (tac s)
(λ a s', result.success a s)
result.exception
/-- Repeat a tactic at least once, calling it recursively on all subgoals,
until it fails. This tactic fails if the first invocation fails. -/
meta def repeat1 (t : tactic unit) : tactic unit := t; repeat t
/-- `iterate_range m n t`: Repeat the given tactic at least `m` times and
at most `n` times or until `t` fails. Fails if `t` does not run at least m times. -/
meta def iterate_range : ℕ → ℕ → tactic unit → tactic unit
| 0 0 t := skip
| 0 (n+1) t := try (t >> iterate_range 0 n t)
| (m+1) n t := t >> iterate_range m (n-1) t
meta def replace_at (tac : expr → tactic (expr × expr)) (hs : list expr) (tgt : bool) : tactic bool :=
do to_remove ← hs.mfilter $ λ h, do {
h_type ← infer_type h,
succeeds $ do
(new_h_type, pr) ← tac h_type,
assert h.local_pp_name new_h_type,
mk_eq_mp pr h >>= tactic.exact },
goal_simplified ← succeeds $ do {
guard tgt,
(new_t, pr) ← target >>= tac,
replace_target new_t pr },
to_remove.mmap' (λ h, try (clear h)),
return (¬ to_remove.empty ∨ goal_simplified)
meta def simp_bottom_up' (post : expr → tactic (expr × expr)) (e : expr) (cfg : simp_config := {}) : tactic (expr × expr) :=
prod.snd <$> simplify_bottom_up () (λ _, (<$>) (prod.mk ()) ∘ post) e cfg
meta structure instance_cache :=
(α : expr)
(univ : level)
(inst : name_map expr)
meta def mk_instance_cache (α : expr) : tactic instance_cache :=
do u ← mk_meta_univ,
infer_type α >>= unify (expr.sort (level.succ u)),
u ← get_univ_assignment u,
return ⟨α, u, mk_name_map⟩
namespace instance_cache
meta def get (c : instance_cache) (n : name) : tactic (instance_cache × expr) :=
match c.inst.find n with
| some i := return (c, i)
| none := do e ← mk_app n [c.α] >>= mk_instance,
return (⟨c.α, c.univ, c.inst.insert n e⟩, e)
end
open expr
meta def append_typeclasses : expr → instance_cache → list expr →
tactic (instance_cache × list expr)
| (pi _ binder_info.inst_implicit (app (const n _) (var _)) body) c l :=
do (c, p) ← c.get n, return (c, p :: l)
| _ c l := return (c, l)
meta def mk_app (c : instance_cache) (n : name) (l : list expr) : tactic (instance_cache × expr) :=
do d ← get_decl n,
(c, l) ← append_typeclasses d.type.binding_body c l,
return (c, (expr.const n [c.univ]).mk_app (c.α :: l))
end instance_cache
meta def match_head (e : expr) : expr → tactic unit
| e' :=
unify e e'
<|> do `(_ → %%e') ← whnf e',
v ← mk_mvar,
match_head (e'.instantiate_var v)
meta def find_matching_head : expr → list expr → tactic (list expr)
| e [] := return []
| e (H :: Hs) :=
do t ← infer_type H,
((::) H <$ match_head e t <|> pure id) <*> find_matching_head e Hs
meta def subst_locals (s : list (expr × expr)) (e : expr) : expr :=
(e.abstract_locals (s.map (expr.local_uniq_name ∘ prod.fst)).reverse).instantiate_vars (s.map prod.snd)
meta def set_binder : expr → list binder_info → expr
| e [] := e
| (expr.pi v _ d b) (bi :: bs) := expr.pi v bi d (set_binder b bs)
| e _ := e
meta def last_explicit_arg : expr → tactic expr
| (expr.app f e) :=
do t ← infer_type f >>= whnf,
if t.binding_info = binder_info.default
then pure e
else last_explicit_arg f
| e := pure e
private meta def get_expl_pi_arity_aux : expr → tactic nat
| (expr.pi n bi d b) :=
do m ← mk_fresh_name,
let l := expr.local_const m n bi d,
new_b ← whnf (expr.instantiate_var b l),
r ← get_expl_pi_arity_aux new_b,
if bi = binder_info.default then
return (r + 1)
else
return r
| e := return 0
/-- Compute the arity of explicit arguments of the given (Pi-)type -/
meta def get_expl_pi_arity (type : expr) : tactic nat :=
whnf type >>= get_expl_pi_arity_aux
/-- Compute the arity of explicit arguments of the given function -/
meta def get_expl_arity (fn : expr) : tactic nat :=
infer_type fn >>= get_expl_pi_arity
/-- variation on `assert` where a (possibly incomplete)
proof of the assertion is provided as a parameter.
``(h,gs) ← local_proof `h p tac`` creates a local `h : p` and
use `tac` to (partially) construct a proof for it. `gs` is the
list of remaining goals in the proof of `h`.
The benefits over assert are:
- unlike with ``h ← assert `h p, tac`` , `h` cannot be used by `tac`;
- when `tac` does not complete the proof of `h`, returning the list
of goals allows one to write a tactic using `h` and with the confidence
that a proof will not boil over to goals left over from the proof of `h`,
unlike what would be the case when using `tactic.swap`.
-/
meta def local_proof (h : name) (p : expr) (tac₀ : tactic unit) :
tactic (expr × list expr) :=
focus1 $
do h' ← assert h p,
[g₀,g₁] ← get_goals,
set_goals [g₀], tac₀,
gs ← get_goals,
set_goals [g₁],
return (h', gs)
meta def var_names : expr → list name
| (expr.pi n _ _ b) := n :: var_names b
| _ := []
meta def drop_binders : expr → tactic expr
| (expr.pi n bi t b) := b.instantiate_var <$> mk_local' n bi t >>= drop_binders
| e := pure e
meta def subobject_names (struct_n : name) : tactic (list name × list name) :=
do env ← get_env,
[c] ← pure $ env.constructors_of struct_n | fail "too many constructors",
vs ← var_names <$> (mk_const c >>= infer_type),
fields ← env.structure_fields struct_n,
return $ fields.partition (λ fn, ↑("_" ++ fn.to_string) ∈ vs)
meta def expanded_field_list' : name → tactic (dlist $ name × name) | struct_n :=
do (so,fs) ← subobject_names struct_n,
ts ← so.mmap (λ n, do
e ← mk_const (n.update_prefix struct_n) >>= infer_type >>= drop_binders,
expanded_field_list' $ e.get_app_fn.const_name),
return $ dlist.join ts ++ dlist.of_list (fs.map $ prod.mk struct_n)
open functor function
meta def expanded_field_list (struct_n : name) : tactic (list $ name × name) :=
dlist.to_list <$> expanded_field_list' struct_n
meta def get_classes (e : expr) : tactic (list name) :=
attribute.get_instances `class >>= list.mfilter (λ n,
succeeds $ mk_app n [e] >>= mk_instance)
open nat
meta def mk_mvar_list : ℕ → tactic (list expr)
| 0 := pure []
| (succ n) := (::) <$> mk_mvar <*> mk_mvar_list n
/-- Returns the only goal, or fails if there isn't just one goal. -/
meta def get_goal : tactic expr :=
do gs ← get_goals,
match gs with
| [a] := return a
| [] := fail "there are no goals"
| _ := fail "there are too many goals"
end
/--`iterate_at_most_on_all_goals n t`: repeat the given tactic at most `n` times on all goals,
or until it fails. Always succeeds. -/
meta def iterate_at_most_on_all_goals : nat → tactic unit → tactic unit
| 0 tac := trace "maximal iterations reached"
| (succ n) tac := tactic.all_goals $ (do tac, iterate_at_most_on_all_goals n tac) <|> skip
/--`iterate_at_most_on_subgoals n t`: repeat the tactic `t` at most `n` times on the first
goal and on all subgoals thus produced, or until it fails. Fails iff `t` fails on
current goal. -/
meta def iterate_at_most_on_subgoals : nat → tactic unit → tactic unit
| 0 tac := trace "maximal iterations reached"
| (succ n) tac := focus1 (do tac, iterate_at_most_on_all_goals n tac)
/--`apply_list l`: try to apply the tactics in the list `l` on the first goal, and
fail if none succeeds -/
meta def apply_list_expr : list expr → tactic unit
| [] := fail "no matching rule"
| (h::t) := do interactive.concat_tags (apply h) <|> apply_list_expr t
/-- constructs a list of expressions given a list of p-expressions, as follows:
- if the p-expression is the name of a theorem, use `i_to_expr_for_apply` on it
- if the p-expression is a user attribute, add all the theorems with this attribute
to the list.-/
meta def build_list_expr_for_apply : list pexpr → tactic (list expr)
| [] := return []
| (h::t) := do
tail ← build_list_expr_for_apply t,
a ← i_to_expr_for_apply h,
(do l ← attribute.get_instances (expr.const_name a),
m ← list.mmap mk_const l,
return (m.append tail))
<|> return (a::tail)
/--`apply_rules hs n`: apply the list of rules `hs` (given as pexpr) and `assumption` on the
first goal and the resulting subgoals, iteratively, at most `n` times -/
meta def apply_rules (hs : list pexpr) (n : nat) : tactic unit :=
do l ← build_list_expr_for_apply hs,
iterate_at_most_on_subgoals n (assumption <|> apply_list_expr l)
meta def replace (h : name) (p : pexpr) : tactic unit :=
do h' ← get_local h,
p ← to_expr p,
note h none p,
clear h'
/-- Auxiliary function for `iff_mp` and `iff_mpr`. Takes a name, which should be either `` `iff.mp``
or `` `iff.mpr``. If the passed expression is an iterated function type eventually producing an
`iff`, returns an expression with the `iff` converted to either the forwards or backwards
implication, as requested. -/
meta def mk_iff_mp_app (iffmp : name) : expr → (nat → expr) → option expr
| (expr.pi n bi e t) f := expr.lam n bi e <$> mk_iff_mp_app t (λ n, f (n+1) (expr.var n))
| `(%%a ↔ %%b) f := some $ @expr.const tt iffmp [] a b (f 0)
| _ f := none
meta def iff_mp_core (e ty: expr) : option expr :=
mk_iff_mp_app `iff.mp ty (λ_, e)
meta def iff_mpr_core (e ty: expr) : option expr :=
mk_iff_mp_app `iff.mpr ty (λ_, e)
/-- Given an expression whose type is (a possibly iterated function producing) an `iff`,
create the expression which is the forward implication. -/
meta def iff_mp (e : expr) : tactic expr :=
do t ← infer_type e,
iff_mp_core e t <|> fail "Target theorem must have the form `Π x y z, a ↔ b`"
/-- Given an expression whose type is (a possibly iterated function producing) an `iff`,
create the expression which is the reverse implication. -/
meta def iff_mpr (e : expr) : tactic expr :=
do t ← infer_type e,
iff_mpr_core e t <|> fail "Target theorem must have the form `Π x y z, a ↔ b`"
/--
Attempts to apply `e`, and if that fails, if `e` is an `iff`,
try applying both directions separately.
-/
meta def apply_iff (e : expr) : tactic (list (name × expr)) :=
let ap e := tactic.apply e {new_goals := new_goals.non_dep_only} in
ap e <|> (iff_mp e >>= ap) <|> (iff_mpr e >>= ap)
meta def symm_apply (e : expr) (cfg : apply_cfg := {}) : tactic (list (name × expr)) :=
tactic.apply e cfg <|> (symmetry >> tactic.apply e cfg)
meta def apply_assumption
(asms : tactic (list expr) := local_context)
(tac : tactic unit := skip) : tactic unit :=
do { ctx ← asms,
ctx.any_of (λ H, symm_apply H >> tac) } <|>
do { exfalso,
ctx ← asms,
ctx.any_of (λ H, symm_apply H >> tac) }
<|> fail "assumption tactic failed"
meta def change_core (e : expr) : option expr → tactic unit
| none := tactic.change e
| (some h) :=
do num_reverted : ℕ ← revert h,
expr.pi n bi d b ← target,
tactic.change $ expr.pi n bi e b,
intron num_reverted
/--
assuming olde and newe are defeq when elaborated, replaces occurences of olde with newe at hypothesis h.
-/
meta def change_with_at (olde newe : pexpr) (hyp : name) : tactic unit :=
do h ← get_local hyp,
tp ← infer_type h,
olde ← to_expr olde, newe ← to_expr newe,
let repl_tp := tp.replace (λ a n, if a = olde then some newe else none),
change_core repl_tp (some h)
meta def metavariables : tactic (list expr) :=
do r ← result,
pure (r.list_meta_vars)
/-- Succeeds only if the current goal is a proposition. -/
meta def propositional_goal : tactic unit :=
do goals ← get_goals,
p ← is_proof goals.head,
guard p
/-- Succeeds only if we can construct an instance showing the
current goal is a subsingleton type. -/
meta def subsingleton_goal : tactic unit :=
do goals ← get_goals,
ty ← infer_type goals.head >>= instantiate_mvars,
to_expr ``(subsingleton %%ty) >>= mk_instance >> skip
/-- Succeeds only if the current goal is "terminal", in the sense
that no other goals depend on it. -/
meta def terminal_goal : tactic unit :=
-- We can't merely test for subsingletons, as sometimes in the presence of metavariables
-- `propositional_goal` succeeds while `subsingleton_goal` does not.
propositional_goal <|> subsingleton_goal <|>
do g₀ :: _ ← get_goals,
mvars ← (λ L, list.erase L g₀) <$> metavariables,
mvars.mmap' $ λ g, do
t ← infer_type g >>= instantiate_mvars,
d ← kdepends_on t g₀,
monad.whenb d $
pp t >>= λ s, fail ("The current goal is not terminal: " ++ s.to_string ++ " depends on it.")
meta def triv' : tactic unit := do c ← mk_const `trivial, exact c reducible
variable {α : Type}
private meta def iterate_aux (t : tactic α) : list α → tactic (list α)
| L := (do r ← t, iterate_aux (r :: L)) <|> return L
/-- Apply a tactic as many times as possible, collecting the results in a list. -/
meta def iterate' (t : tactic α) : tactic (list α) :=
list.reverse <$> iterate_aux t []
/-- Like iterate', but fail if the tactic does not succeed at least once. -/
meta def iterate1 (t : tactic α) : tactic (α × list α) :=
do r ← decorate_ex "iterate1 failed: tactic did not succeed" t,
L ← iterate' t,
return (r, L)
meta def intros1 : tactic (list expr) :=
iterate1 intro1 >>= λ p, return (p.1 :: p.2)
/-- `successes` invokes each tactic in turn, returning the list of successful results. -/
meta def successes (tactics : list (tactic α)) : tactic (list α) :=
list.filter_map id <$> monad.sequence (tactics.map (λ t, try_core t))
/-- Return target after instantiating metavars and whnf -/
private meta def target' : tactic expr :=
target >>= instantiate_mvars >>= whnf
/--
Just like `split`, `fsplit` applies the constructor when the type of the target is an inductive data type with one constructor.
However it does not reorder goals or invoke `auto_param` tactics.
-/
-- FIXME check if we can remove `auto_param := ff`
meta def fsplit : tactic unit :=
do [c] ← target' >>= get_constructors_for | tactic.fail "fsplit tactic failed, target is not an inductive datatype with only one constructor",
mk_const c >>= λ e, apply e {new_goals := new_goals.all, auto_param := ff} >> skip
run_cmd add_interactive [`fsplit]
/-- Calls `injection` on each hypothesis, and then, for each hypothesis on which `injection`
succeeds, clears the old hypothesis. -/
meta def injections_and_clear : tactic unit :=
do l ← local_context,
results ← successes $ l.map $ λ e, injection e >> clear e,
when (results.empty) (fail "could not use `injection` then `clear` on any hypothesis")
run_cmd add_interactive [`injections_and_clear]
/-- calls `cases` on every local hypothesis, succeeding if
it succeeds on at least one hypothesis. -/
meta def case_bash : tactic unit :=
do l ← local_context,
r ← successes (l.reverse.map (λ h, cases h >> skip)),
when (r.empty) failed
meta def note_anon (e : expr) : tactic expr :=
do n ← get_unused_name "lh",
note n none e
/-- `find_local t` returns a local constant with type t, or fails if none exists. -/
meta def find_local (t : pexpr) : tactic expr :=
do t' ← to_expr t,
prod.snd <$> solve_aux t' assumption
/-- `dependent_pose_core l`: introduce dependent hypothesis, where the proofs depend on the values
of the previous local constants. `l` is a list of local constants and their values. -/
meta def dependent_pose_core (l : list (expr × expr)) : tactic unit := do
let lc := l.map prod.fst,
let lm := l.map (λ⟨l, v⟩, (l.local_uniq_name, v)),
t ← target,
new_goal ← mk_meta_var (t.pis lc),
old::other_goals ← get_goals,
set_goals (old :: new_goal :: other_goals),
exact ((new_goal.mk_app lc).instantiate_locals lm),
return ()
/-- like `mk_local_pis` but translating into weak head normal form before checking if it is a Π. -/
meta def mk_local_pis_whnf : expr → tactic (list expr × expr) | e := do
(expr.pi n bi d b) ← whnf e | return ([], e),
p ← mk_local' n bi d,
(ps, r) ← mk_local_pis (expr.instantiate_var b p),
return ((p :: ps), r)
/-- Changes `(h : ∀xs, ∃a:α, p a) ⊢ g` to `(d : ∀xs, a) (s : ∀xs, p (d xs) ⊢ g` -/
meta def choose1 (h : expr) (data : name) (spec : name) : tactic expr := do
t ← infer_type h,
(ctxt, t) ← mk_local_pis_whnf t,
`(@Exists %%α %%p) ← whnf t transparency.all | fail "expected a term of the shape ∀xs, ∃a, p xs a",
α_t ← infer_type α,
expr.sort u ← whnf α_t transparency.all,
value ← mk_local_def data (α.pis ctxt),
t' ← head_beta (p.app (value.mk_app ctxt)),
spec ← mk_local_def spec (t'.pis ctxt),
dependent_pose_core [
(value, ((((expr.const `classical.some [u]).app α).app p).app (h.mk_app ctxt)).lambdas ctxt),
(spec, ((((expr.const `classical.some_spec [u]).app α).app p).app (h.mk_app ctxt)).lambdas ctxt)],
try (tactic.clear h),
intro1,
intro1
/-- Changes `(h : ∀xs, ∃as, p as) ⊢ g` to a list of functions `as`, an a final hypothesis on `p as` -/
meta def choose : expr → list name → tactic unit
| h [] := fail "expect list of variables"
| h [n] := do
cnt ← revert h,
intro n,
intron (cnt - 1),
return ()
| h (n::ns) := do
v ← get_unused_name >>= choose1 h n,
choose v ns
/-- This makes sure that the execution of the tactic does not change the tactic state.
This can be helpful while using rewrite, apply, or expr munging.
Remember to instantiate your metavariables before you're done! -/
meta def lock_tactic_state {α} (t : tactic α) : tactic α
| s := match t s with
| result.success a s' := result.success a s
| result.exception msg pos s' := result.exception msg pos s
end
/--
Hole command used to fill in a structure's field when specifying an instance.
In the following:
```
instance : monad id :=
{! !}
```
invoking hole command `Instance Stub` produces:
```
instance : monad id :=
{ map := _,
map_const := _,
pure := _,
seq := _,
seq_left := _,
seq_right := _,
bind := _ }
```
-/
@[hole_command] meta def instance_stub : hole_command :=
{ name := "Instance Stub",
descr := "Generate a skeleton for the structure under construction.",
action := λ _,
do tgt ← target >>= whnf,
let cl := tgt.get_app_fn.const_name,
env ← get_env,
fs ← expanded_field_list cl,
let fs := fs.map prod.snd,
let fs := format.intercalate (",\n " : format) $ fs.map (λ fn, format!"{fn} := _"),
let out := format.to_string format!"{{ {fs} }",
return [(out,"")] }
meta def strip_prefix' (n : name) : list string → name → tactic name
| s name.anonymous := pure $ s.foldl (flip name.mk_string) name.anonymous
| s (name.mk_string a p) :=
do let n' := s.foldl (flip name.mk_string) name.anonymous,
do { n'' ← tactic.resolve_constant n',
if n'' = n
then pure n'
else strip_prefix' (a :: s) p }
<|> strip_prefix' (a :: s) p
| s (name.mk_numeral a p) := interaction_monad.failed
meta def strip_prefix : name → tactic name
| n@(name.mk_string a a_1) := strip_prefix' n [a] a_1
| _ := interaction_monad.failed
meta def is_default_local : expr → bool
| (expr.local_const _ _ binder_info.default _) := tt
| _ := ff
meta def mk_patterns (t : expr) : tactic (list format) :=
do let cl := t.get_app_fn.const_name,
env ← get_env,
let fs := env.constructors_of cl,
fs.mmap $ λ f,
do { (vs,_) ← mk_const f >>= infer_type >>= mk_local_pis,
let vs := vs.filter (λ v, is_default_local v),
vs ← vs.mmap (λ v,
do v' ← get_unused_name v.local_pp_name,
pose v' none `(()),
pure v' ),
vs.mmap' $ λ v, get_local v >>= clear,
let args := list.intersperse (" " : format) $ vs.map to_fmt,
f ← strip_prefix f,
if args.empty
then pure $ format!"| {f} := _\n"
else pure format!"| ({f} {format.join args}) := _\n" }
/--
Hole command used to generate a `match` expression.
In the following:
```
meta def foo (e : expr) : tactic unit :=
{! e !}
```
invoking hole command `Match Stub` produces:
```
meta def foo (e : expr) : tactic unit :=
match e with
| (expr.var a) := _
| (expr.sort a) := _
| (expr.const a a_1) := _
| (expr.mvar a a_1 a_2) := _
| (expr.local_const a a_1 a_2 a_3) := _
| (expr.app a a_1) := _
| (expr.lam a a_1 a_2 a_3) := _
| (expr.pi a a_1 a_2 a_3) := _
| (expr.elet a a_1 a_2 a_3) := _
| (expr.macro a a_1) := _
end
```
-/
@[hole_command] meta def match_stub : hole_command :=
{ name := "Match Stub",
descr := "Generate a list of equations for a `match` expression.",
action := λ es,
do [e] ← pure es | fail "expecting one expression",
e ← to_expr e,
t ← infer_type e >>= whnf,
fs ← mk_patterns t,
e ← pp e,
let out := format.to_string format!"match {e} with\n{format.join fs}end\n",
return [(out,"")] }
/--
Hole command used to generate a `match` expression.
In the following:
```
meta def foo : {! expr → tactic unit !} -- `:=` is omitted
```
invoking hole command `Equations Stub` produces:
```
meta def foo : expr → tactic unit
| (expr.var a) := _
| (expr.sort a) := _
| (expr.const a a_1) := _
| (expr.mvar a a_1 a_2) := _
| (expr.local_const a a_1 a_2 a_3) := _
| (expr.app a a_1) := _
| (expr.lam a a_1 a_2 a_3) := _
| (expr.pi a a_1 a_2 a_3) := _
| (expr.elet a a_1 a_2 a_3) := _
| (expr.macro a a_1) := _
```
A similar result can be obtained by invoking `Equations Stub` on the following:
```
meta def foo : expr → tactic unit := -- do not forget to write `:=`!!
{! !}
```
```
meta def foo : expr → tactic unit := -- don't forget to erase `:=`!!
| (expr.var a) := _
| (expr.sort a) := _
| (expr.const a a_1) := _
| (expr.mvar a a_1 a_2) := _
| (expr.local_const a a_1 a_2 a_3) := _
| (expr.app a a_1) := _
| (expr.lam a a_1 a_2 a_3) := _
| (expr.pi a a_1 a_2 a_3) := _
| (expr.elet a a_1 a_2 a_3) := _
| (expr.macro a a_1) := _
```
-/
@[hole_command] meta def eqn_stub : hole_command :=
{ name := "Equations Stub",
descr := "Generate a list of equations for a recursive definition.",
action := λ es,
do t ← match es with
| [t] := to_expr t
| [] := target
| _ := fail "expecting one type"
end,
e ← whnf t,
(v :: _,_) ← mk_local_pis e | fail "expecting a Pi-type",
t' ← infer_type v,
fs ← mk_patterns t',
t ← pp t,
let out :=
if es.empty then
format.to_string format!"-- do not forget to erase `:=`!!\n{format.join fs}"
else format.to_string format!"{t}\n{format.join fs}",
return [(out,"")] }
/--
This command lists the constructors that can be used to satisfy the expected type.
When used in the following hole:
```
def foo : ℤ ⊕ ℕ :=
{! !}
```
the command will produce:
```
def foo : ℤ ⊕ ℕ :=
{! sum.inl, sum.inr !}
```
and will display:
```
sum.inl : ℤ → ℤ ⊕ ℕ
sum.inr : ℕ → ℤ ⊕ ℕ
```
-/
@[hole_command] meta def list_constructors_hole : hole_command :=
{ name := "List Constructors",
descr := "Show the list of constructors of the expected type.",
action := λ es,
do t ← target >>= whnf,
(_,t) ← mk_local_pis t,
let cl := t.get_app_fn.const_name,
let args := t.get_app_args,
env ← get_env,
let cs := env.constructors_of cl,
ts ← cs.mmap $ λ c,
do { e ← mk_const c,
t ← infer_type (e.mk_app args) >>= pp,
c ← strip_prefix c,
pure format!"\n{c} : {t}\n" },
fs ← format.intercalate ", " <$> cs.mmap (strip_prefix >=> pure ∘ to_fmt),
let out := format.to_string format!"{{! {fs} !}",
trace (format.join ts).to_string,
return [(out,"")] }
meta def classical : tactic unit :=
do h ← get_unused_name `_inst,
mk_const `classical.prop_decidable >>= note h none,
reset_instance_cache
open expr
meta def add_prime : name → name
| (name.mk_string s p) := name.mk_string (s ++ "'") p
| n := (name.mk_string "x'" n)
meta def mk_comp (v : expr) : expr → tactic expr
| (app f e) :=
if e = v then pure f
else do
guard (¬ v.occurs f) <|> fail "bad guard",
e' ← mk_comp e >>= instantiate_mvars,
f ← instantiate_mvars f,
mk_mapp ``function.comp [none,none,none,f,e']
| e :=
do guard (e = v),
t ← infer_type e,
mk_mapp ``id [t]
meta def mk_higher_order_type : expr → tactic expr
| (pi n bi d b@(pi _ _ _ _)) :=
do v ← mk_local_def n d,
let b' := (b.instantiate_var v),
(pi n bi d ∘ flip abstract_local v.local_uniq_name) <$> mk_higher_order_type b'
| (pi n bi d b) :=
do v ← mk_local_def n d,
let b' := (b.instantiate_var v),
(l,r) ← match_eq b' <|> fail format!"not an equality {b'}",
l' ← mk_comp v l,
r' ← mk_comp v r,
mk_app ``eq [l',r']
| e := failed
open lean.parser interactive.types
@[user_attribute]
meta def higher_order_attr : user_attribute unit (option name) :=
{ name := `higher_order,
parser := optional ident,
descr :=
"From a lemma of the shape `f (g x) = h x` derive an auxiliary lemma of the
form `f ∘ g = h` for reasoning about higher-order functions.",
after_set := some $ λ lmm _ _,
do env ← get_env,
decl ← env.get lmm,
let num := decl.univ_params.length,
let lvls := (list.iota num).map (`l).append_after,
let l : expr := expr.const lmm $ lvls.map level.param,
t ← infer_type l >>= instantiate_mvars,
t' ← mk_higher_order_type t,
(_,pr) ← solve_aux t' $ do {
intros, applyc ``_root_.funext, intro1, applyc lmm; assumption },
pr ← instantiate_mvars pr,
lmm' ← higher_order_attr.get_param lmm,
lmm' ← (flip name.update_prefix lmm.get_prefix <$> lmm') <|> pure (add_prime lmm),
add_decl $ declaration.thm lmm' lvls t' (pure pr),
copy_attribute `simp lmm tt lmm',
copy_attribute `functor_norm lmm tt lmm' }
attribute [higher_order map_comp_pure] map_pure
private meta def tactic.use_aux (h : pexpr) : tactic unit :=
(focus1 (refine h >> done)) <|> (fconstructor >> tactic.use_aux)
meta def tactic.use (l : list pexpr) : tactic unit :=
focus1 $ l.mmap' $ λ h, tactic.use_aux h <|> fail format!"failed to instantiate goal with {h}"
meta def clear_aux_decl_aux : list expr → tactic unit
| [] := skip
| (e::l) := do cond e.is_aux_decl (tactic.clear e) skip, clear_aux_decl_aux l
meta def clear_aux_decl : tactic unit :=
local_context >>= clear_aux_decl_aux
precedence `setup_tactic_parser`:0
@[user_command]
meta def setup_tactic_parser_cmd (_ : interactive.parse $ tk "setup_tactic_parser") : lean.parser unit :=
emit_code_here "
open lean
open lean.parser
open interactive interactive.types
local postfix `?`:9001 := optional
local postfix *:9001 := many .
"
/--
This combinator is for testing purposes. It succeeds if `t` fails with message `msg`,
and fails otherwise.
-/
meta def {u} success_if_fail_with_msg {α : Type u} (t : tactic α) (msg : string) : tactic unit :=
λ s, match t s with
| (interaction_monad.result.exception msg' _ s') :=
if msg = (msg'.iget ()).to_string then result.success () s
else mk_exception "failure messages didn't match" none s
| (interaction_monad.result.success a s) :=
mk_exception "success_if_fail_with_msg combinator failed, given tactic succeeded" none s
end
open lean interactive
meta def pformat := tactic format
meta def pformat.mk (fmt : format) : pformat := pure fmt
meta def to_pfmt {α} [has_to_tactic_format α] (x : α) : pformat :=
pp x
meta instance pformat.has_to_tactic_format : has_to_tactic_format pformat :=
⟨ id ⟩
meta instance : has_append pformat :=
⟨ λ x y, (++) <$> x <*> y ⟩
private meta def parse_pformat : string → list char → parser pexpr
| acc [] := pure ``(to_pfmt %%(reflect acc))
| acc ('\n'::s) :=
do f ← parse_pformat "" s,
pure ``(to_pfmt %%(reflect acc) ++ pformat.mk format.line ++ %%f)
| acc ('{'::'{'::s) := parse_pformat (acc ++ "{") s
| acc ('{'::s) :=
do (e, s) ← with_input (lean.parser.pexpr 0) s.as_string,
'}'::s ← return s.to_list | fail "'}' expected",
f ← parse_pformat "" s,
pure ``(to_pfmt %%(reflect acc) ++ to_pfmt %%e ++ %%f)
| acc (c::s) := parse_pformat (acc.str c) s
reserve prefix `pformat! `:100
/-- See `format!` in `init/meta/interactive_base.lean`. The only difference is that `pp` is called instead of `to_fmt` -/
@[user_notation]
meta def pformat_macro (_ : parse $ tk "pformat!") (s : string) : parser pexpr :=
parse_pformat "" s.to_list
end tactic
|
08864c882beca9b46f5298507e91e796404d57f7 | 35677d2df3f081738fa6b08138e03ee36bc33cad | /src/order/fixed_points.lean | 988bc8548c6e80eb3f3a40f19802e990d442f03d | [
"Apache-2.0"
] | permissive | gebner/mathlib | eab0150cc4f79ec45d2016a8c21750244a2e7ff0 | cc6a6edc397c55118df62831e23bfbd6e6c6b4ab | refs/heads/master | 1,625,574,853,976 | 1,586,712,827,000 | 1,586,712,827,000 | 99,101,412 | 1 | 0 | Apache-2.0 | 1,586,716,389,000 | 1,501,667,958,000 | Lean | UTF-8 | Lean | false | false | 8,824 | lean | /-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Kenny Lau
Fixed point construction on complete lattices.
-/
import order.complete_lattice
universes u v w
variables {α : Type u} {β : Type v} {γ : Type w}
/-- The set of fixed points of a self-map -/
def fixed_points (f : α → α) : set α := { x | f x = x }
section fixedpoint
variables [complete_lattice α] {f : α → α}
/-- Least fixed point of a monotone function -/
def lfp (f : α → α) : α := Inf {a | f a ≤ a}
/-- Greatest fixed point of a monotone function -/
def gfp (f : α → α) : α := Sup {a | a ≤ f a}
theorem lfp_le {a : α} (h : f a ≤ a) : lfp f ≤ a :=
Inf_le h
theorem le_lfp {a : α} (h : ∀b, f b ≤ b → a ≤ b) : a ≤ lfp f :=
le_Inf h
theorem lfp_eq (m : monotone f) : lfp f = f (lfp f) :=
have f (lfp f) ≤ lfp f,
from le_lfp $ assume b, assume h : f b ≤ b, le_trans (m (lfp_le h)) h,
le_antisymm (lfp_le (m this)) this
theorem lfp_induct {p : α → Prop} (m : monotone f)
(step : ∀a, p a → a ≤ lfp f → p (f a)) (sup : ∀s, (∀a∈s, p a) → p (Sup s)) :
p (lfp f) :=
let s := {a | a ≤ lfp f ∧ p a} in
have p_s : p (Sup s),
from sup s (assume a ⟨_, h⟩, h),
have Sup s ≤ lfp f,
from le_lfp $ assume a, assume h : f a ≤ a, Sup_le $ assume b ⟨b_le, _⟩, le_trans b_le (lfp_le h),
have Sup s = lfp f,
from le_antisymm this $ lfp_le $ le_Sup
⟨le_trans (m this) $ ge_of_eq $ lfp_eq m, step _ p_s this⟩,
this ▸ p_s
theorem monotone_lfp : monotone (@lfp α _) :=
assume f g, assume : f ≤ g, le_lfp $ assume a, assume : g a ≤ a, lfp_le $ le_trans (‹f ≤ g› a) this
theorem le_gfp {a : α} (h : a ≤ f a) : a ≤ gfp f :=
le_Sup h
theorem gfp_le {a : α} (h : ∀b, b ≤ f b → b ≤ a) : gfp f ≤ a :=
Sup_le h
theorem gfp_eq (m : monotone f) : gfp f = f (gfp f) :=
have gfp f ≤ f (gfp f),
from gfp_le $ assume b, assume h : b ≤ f b, le_trans h (m (le_gfp h)),
le_antisymm this (le_gfp (m this))
theorem gfp_induct {p : α → Prop} (m : monotone f)
(step : ∀a, p a → gfp f ≤ a → p (f a)) (inf : ∀s, (∀a∈s, p a) → p (Inf s)) :
p (gfp f) :=
let s := {a | gfp f ≤ a ∧ p a} in
have p_s : p (Inf s),
from inf s (assume a ⟨_, h⟩, h),
have gfp f ≤ Inf s,
from gfp_le $ assume a, assume h : a ≤ f a, le_Inf $ assume b ⟨le_b, _⟩, le_trans (le_gfp h) le_b,
have Inf s = gfp f,
from le_antisymm (le_gfp $ Inf_le
⟨le_trans (le_of_eq $ gfp_eq m) (m this), step _ p_s this⟩) this,
this ▸ p_s
theorem monotone_gfp : monotone (@gfp α _) :=
assume f g, assume : f ≤ g, gfp_le $ assume a, assume : a ≤ f a, le_gfp $ le_trans this (‹f ≤ g› a)
end fixedpoint
section fixedpoint_eqn
variables [complete_lattice α] [complete_lattice β] {f : β → α} {g : α → β}
-- Rolling rule
theorem lfp_comp (m_f : monotone f) (m_g : monotone g) : lfp (f ∘ g) = f (lfp (g ∘ f)) :=
le_antisymm
(lfp_le $ m_f $ ge_of_eq $ lfp_eq $ m_g.comp m_f)
(le_lfp $ assume a fg_le,
le_trans (m_f $ lfp_le $ show (g ∘ f) (g a) ≤ g a, from m_g fg_le) fg_le)
theorem gfp_comp (m_f : monotone f) (m_g : monotone g) : gfp (f ∘ g) = f (gfp (g ∘ f)) :=
le_antisymm
(gfp_le $ assume a fg_le,
le_trans fg_le $ m_f $ le_gfp $ show g a ≤ (g ∘ f) (g a), from m_g fg_le)
(le_gfp $ m_f $ le_of_eq $ gfp_eq $ m_g.comp m_f)
-- Diagonal rule
theorem lfp_lfp {h : α → α → α} (m : ∀⦃a b c d⦄, a ≤ b → c ≤ d → h a c ≤ h b d) :
lfp (lfp ∘ h) = lfp (λx, h x x) :=
let f := lfp (lfp ∘ h) in
have f_eq : f = lfp (h f),
from lfp_eq $ monotone.comp monotone_lfp (assume a b h x, m h (le_refl _)) ,
le_antisymm
(lfp_le $ lfp_le $ ge_of_eq $ lfp_eq $ assume a b h, m h h)
(lfp_le $ ge_of_eq $
calc f = lfp (h f) : f_eq
... = h f (lfp (h f)) : lfp_eq $ assume a b h, m (le_refl _) h
... = h f f : congr_arg (h f) f_eq.symm)
theorem gfp_gfp {h : α → α → α} (m : ∀⦃a b c d⦄, a ≤ b → c ≤ d → h a c ≤ h b d) :
gfp (gfp ∘ h) = gfp (λx, h x x) :=
let f := gfp (gfp ∘ h) in
have f_eq : f = gfp (h f),
from gfp_eq $ monotone.comp monotone_gfp (assume a b h x, m h (le_refl _)),
le_antisymm
(le_gfp $ le_of_eq $
calc f = gfp (h f) : f_eq
... = h f (gfp (h f)) : gfp_eq $ assume a b h, m (le_refl _) h
... = h f f : congr_arg (h f) f_eq.symm)
(le_gfp $ le_gfp $ le_of_eq $ gfp_eq $ assume a b h, m h h)
end fixedpoint_eqn
/- The complete lattice of fixed points of a function f -/
namespace fixed_points
variables [complete_lattice α] (f : α → α) (hf : monotone f)
def prev (x : α) : α := gfp (λ z, x ⊓ f z)
def next (x : α) : α := lfp (λ z, x ⊔ f z)
variable {f}
theorem prev_le {x : α} : prev f x ≤ x := gfp_le $ λ z hz, le_trans hz inf_le_left
lemma prev_eq (hf : monotone f) {a : α} (h : f a ≤ a) : prev f a = f (prev f a) :=
calc prev f a = a ⊓ f (prev f a) :
gfp_eq $ show monotone (λz, a ⊓ f z), from assume x y h, inf_le_inf (le_refl _) (hf h)
... = f (prev f a) :
by rw [inf_of_le_right]; exact le_trans (hf prev_le) h
def prev_fixed (hf : monotone f) (a : α) (h : f a ≤ a) : fixed_points f :=
⟨prev f a, (prev_eq hf h).symm⟩
theorem next_le {x : α} : x ≤ next f x := le_lfp $ λ z hz, le_trans le_sup_left hz
lemma next_eq (hf : monotone f) {a : α} (h : a ≤ f a) : next f a = f (next f a) :=
calc next f a = a ⊔ f (next f a) :
lfp_eq $ show monotone (λz, a ⊔ f z), from assume x y h, sup_le_sup (le_refl _) (hf h)
... = f (next f a) :
by rw [sup_of_le_right]; exact le_trans h (hf next_le)
def next_fixed (hf : monotone f) (a : α) (h : a ≤ f a) : fixed_points f :=
⟨next f a, (next_eq hf h).symm⟩
variable f
theorem sup_le_f_of_fixed_points (x y : fixed_points f) : x.1 ⊔ y.1 ≤ f (x.1 ⊔ y.1) :=
sup_le
(x.2 ▸ (hf $ show x.1 ≤ f x.1 ⊔ y.1, from x.2.symm ▸ le_sup_left))
(y.2 ▸ (hf $ show y.1 ≤ x.1 ⊔ f y.1, from y.2.symm ▸ le_sup_right))
theorem f_le_inf_of_fixed_points (x y : fixed_points f) : f (x.1 ⊓ y.1) ≤ x.1 ⊓ y.1 :=
le_inf
(x.2 ▸ (hf $ show f (x.1) ⊓ y.1 ≤ x.1, from x.2.symm ▸ inf_le_left))
(y.2 ▸ (hf $ show x.1 ⊓ f (y.1) ≤ y.1, from y.2.symm ▸ inf_le_right))
theorem Sup_le_f_of_fixed_points (A : set α) (HA : A ⊆ fixed_points f) : Sup A ≤ f (Sup A) :=
Sup_le $ λ x hxA, (HA hxA) ▸ (hf $ le_Sup hxA)
theorem f_le_Inf_of_fixed_points (A : set α) (HA : A ⊆ fixed_points f) : f (Inf A) ≤ Inf A :=
le_Inf $ λ x hxA, (HA hxA) ▸ (hf $ Inf_le hxA)
/-- The fixed points of `f` form a complete lattice.
This cannot be an instance, since it depends on the monotonicity of `f`. -/
protected def complete_lattice : complete_lattice (fixed_points f) :=
{ le := λx y, x.1 ≤ y.1,
le_refl := λ x, le_refl x,
le_trans := λ x y z, le_trans,
le_antisymm := λ x y hx hy, subtype.eq $ le_antisymm hx hy,
sup := λ x y, next_fixed hf (x.1 ⊔ y.1) (sup_le_f_of_fixed_points f hf x y),
le_sup_left := λ x y, show x.1 ≤ _, from le_trans le_sup_left next_le,
le_sup_right := λ x y, show y.1 ≤ _, from le_trans le_sup_right next_le,
sup_le := λ x y z hxz hyz, lfp_le $ sup_le (sup_le hxz hyz) (z.2.symm ▸ le_refl z.1),
inf := λ x y, prev_fixed hf (x.1 ⊓ y.1) (f_le_inf_of_fixed_points f hf x y),
inf_le_left := λ x y, show _ ≤ x.1, from le_trans prev_le inf_le_left,
inf_le_right := λ x y, show _ ≤ y.1, from le_trans prev_le inf_le_right,
le_inf := λ x y z hxy hxz, le_gfp $ le_inf (le_inf hxy hxz) (x.2.symm ▸ le_refl x),
top := prev_fixed hf ⊤ le_top,
le_top := λ ⟨x, H⟩, le_gfp $ le_inf le_top (H.symm ▸ le_refl x),
bot := next_fixed hf ⊥ bot_le,
bot_le := λ ⟨x, H⟩, lfp_le $ sup_le bot_le (H.symm ▸ le_refl x),
Sup := λ A, next_fixed hf (Sup $ subtype.val '' A)
(Sup_le_f_of_fixed_points f hf (subtype.val '' A) (λ z ⟨x, hx⟩, hx.2 ▸ x.2)),
le_Sup := λ A x hxA, show x.1 ≤ _, from le_trans
(le_Sup $ show x.1 ∈ subtype.val '' A, from ⟨x, hxA, rfl⟩)
next_le,
Sup_le := λ A x Hx, lfp_le $ sup_le (Sup_le $ λ z ⟨y, hyA, hyz⟩, hyz ▸ Hx y hyA) (x.2.symm ▸ le_refl x),
Inf := λ A, prev_fixed hf (Inf $ subtype.val '' A)
(f_le_Inf_of_fixed_points f hf (subtype.val '' A) (λ z ⟨x, hx⟩, hx.2 ▸ x.2)),
le_Inf := λ A x Hx, le_gfp $ le_inf (le_Inf $ λ z ⟨y, hyA, hyz⟩, hyz ▸ Hx y hyA) (x.2.symm ▸ le_refl x.1),
Inf_le := λ A x hxA, show _ ≤ x.1, from le_trans
prev_le
(Inf_le $ show x.1 ∈ subtype.val '' A, from ⟨x, hxA, rfl⟩) }
end fixed_points
|
4bbf45abceffb3594aa1fa13175c653b52905a9a | 0c1546a496eccfb56620165cad015f88d56190c5 | /tests/lean/tactic_state_pp.lean | 2b871b6a4c8df47cf7631fde865e0834eca09482 | [
"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 | 1,092 | lean | universe variables u
inductive Vec (α : Type u) : nat → Type u
| nil : Vec 0
| cons : ∀ {n}, α → Vec n → Vec (nat.succ n)
constant f {α : Type u} {n : nat} : Vec α n → nat
axiom fax1 (α : Type u) : f (Vec.nil α) = 0
axiom fax2 {α : Type u} {n : nat} (v : Vec α (nat.succ n)) : f v = 1
open tactic
meta def pp_state_core : tactic format :=
do t ← target,
t_fmt ← pp t,
return $ to_fmt "Goal: " ++ t_fmt
meta def pp_state (s : tactic_state) : format :=
match pp_state_core s with
| tactic_result.success r _ := r
| tactic_result.exception .format _ _ _ := "failed to pretty print"
end
meta instance i2 : has_to_format tactic_state :=
⟨λ s, to_fmt "My custom goal visualizer" ++ format.line ++ pp_state s⟩
example {α : Type u} {n : nat} (v : Vec α n) : f v ≠ 2 :=
begin
destruct v,
intros, intro, note h := fax1 α, cc,
-- intros n1 h t, intros, intro, note h := fax2 (Vec.cons h t), cc
end
open nat
example : ∀ n, 0 < n → succ (pred n) = n :=
begin
intro n,
destruct n,
dsimp, intros, note h := lt_irrefl 0, cc,
end
|
d944b75128c6b52951f85b03fa754a312b4add03 | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /src/Lean/Elab/Tactic/Basic.lean | a738d781bc19f0bbf4c6292b5b325e0ea385a9ac | [
"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 | 15,768 | 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.Elab.Term
namespace Lean.Elab
open Meta
/-- Assign `mvarId := sorry` -/
def admitGoal (mvarId : MVarId) : MetaM Unit :=
mvarId.withContext do
let mvarType ← inferType (mkMVar mvarId)
mvarId.assign (← mkSorry mvarType (synthetic := true))
def goalsToMessageData (goals : List MVarId) : MessageData :=
MessageData.joinSep (goals.map MessageData.ofGoal) m!"\n\n"
def Term.reportUnsolvedGoals (goals : List MVarId) : MetaM Unit := do
logError <| MessageData.tagged `Tactic.unsolvedGoals <| m!"unsolved goals\n{goalsToMessageData goals}"
goals.forM fun mvarId => admitGoal mvarId
namespace Tactic
structure Context where
/-- Declaration name of the executing elaborator, used by `mkTacticInfo` to persist it in the info tree -/
elaborator : Name
/--
If `true`, enable "error recovery" in some tactics. For example, `cases` tactic
admits unsolved alternatives when `recover == true`. The combinator `withoutRecover <tac>` disables
"error recovery" while executing `<tac>`. This is useful for tactics such as `first | ... | ...`.
-/
recover : Bool := true
structure SavedState where
term : Term.SavedState
tactic : State
abbrev TacticM := ReaderT Context $ StateRefT State TermElabM
abbrev Tactic := Syntax → TacticM Unit
/-
Make the compiler generate specialized `pure`/`bind` so we do not have to optimize through the
whole monad stack at every use site. May eventually be covered by `deriving`.
See comment at `Monad TermElabM`
-/
@[always_inline]
instance : Monad TacticM :=
let i := inferInstanceAs (Monad TacticM);
{ pure := i.pure, bind := i.bind }
def getGoals : TacticM (List MVarId) :=
return (← get).goals
def setGoals (mvarIds : List MVarId) : TacticM Unit :=
modify fun _ => { goals := mvarIds }
def pruneSolvedGoals : TacticM Unit := do
let gs ← getGoals
let gs ← gs.filterM fun g => not <$> g.isAssigned
setGoals gs
def getUnsolvedGoals : TacticM (List MVarId) := do
pruneSolvedGoals
getGoals
@[inline] private def TacticM.runCore (x : TacticM α) (ctx : Context) (s : State) : TermElabM (α × State) :=
x ctx |>.run s
@[inline] private def TacticM.runCore' (x : TacticM α) (ctx : Context) (s : State) : TermElabM α :=
Prod.fst <$> x.runCore ctx s
def run (mvarId : MVarId) (x : TacticM Unit) : TermElabM (List MVarId) :=
mvarId.withContext do
let pendingMVarsSaved := (← get).pendingMVars
modify fun s => { s with pendingMVars := [] }
let aux : TacticM (List MVarId) :=
/- Important: the following `try` does not backtrack the state.
This is intentional because we don't want to backtrack the error messages when we catch the "abort internal exception"
We must define `run` here because we define `MonadExcept` instance for `TacticM` -/
try
x; getUnsolvedGoals
catch ex =>
if isAbortTacticException ex then
getUnsolvedGoals
else
throw ex
try
aux.runCore' { elaborator := .anonymous } { goals := [mvarId] }
finally
modify fun s => { s with pendingMVars := pendingMVarsSaved }
protected def saveState : TacticM SavedState :=
return { term := (← Term.saveState), tactic := (← get) }
def SavedState.restore (b : SavedState) (restoreInfo := false) : TacticM Unit := do
b.term.restore restoreInfo
set b.tactic
protected def getCurrMacroScope : TacticM MacroScope := do pure (← readThe Core.Context).currMacroScope
protected def getMainModule : TacticM Name := do pure (← getEnv).mainModule
unsafe def mkTacticAttribute : IO (KeyedDeclsAttribute Tactic) :=
mkElabAttribute Tactic `builtin_tactic `tactic `Lean.Parser.Tactic `Lean.Elab.Tactic.Tactic "tactic" `Lean.Elab.Tactic.tacticElabAttribute
@[builtin_init mkTacticAttribute] opaque tacticElabAttribute : KeyedDeclsAttribute Tactic
def mkTacticInfo (mctxBefore : MetavarContext) (goalsBefore : List MVarId) (stx : Syntax) : TacticM Info :=
return Info.ofTacticInfo {
elaborator := (← read).elaborator
mctxBefore := mctxBefore
goalsBefore := goalsBefore
stx := stx
mctxAfter := (← getMCtx)
goalsAfter := (← getUnsolvedGoals)
}
def mkInitialTacticInfo (stx : Syntax) : TacticM (TacticM Info) := do
let mctxBefore ← getMCtx
let goalsBefore ← getUnsolvedGoals
return mkTacticInfo mctxBefore goalsBefore stx
@[inline] def withTacticInfoContext (stx : Syntax) (x : TacticM α) : TacticM α := do
withInfoContext x (← mkInitialTacticInfo stx)
/-!
Important: we must define `evalTactic` before we define
the instance `MonadExcept` for `TacticM` since it backtracks the state including error messages,
and this is bad when rethrowing the exception at the `catch` block in these methods.
We marked these places with a `(*)` in these methods.
-/
/--
Auxiliary datastructure for capturing exceptions at `evalTactic`.
-/
structure EvalTacticFailure where
exception : Exception
state : SavedState
partial def evalTactic (stx : Syntax) : TacticM Unit := do
profileitM Exception "tactic execution" (decl := stx.getKind) (← getOptions) <|
withRef stx <| withIncRecDepth <| withFreshMacroScope <| match stx with
| .node _ k _ =>
if k == nullKind then
-- Macro writers create a sequence of tactics `t₁ ... tₙ` using `mkNullNode #[t₁, ..., tₙ]`
stx.getArgs.forM evalTactic
else withTraceNode `Elab.step (fun _ => return stx) do
let evalFns := tacticElabAttribute.getEntries (← getEnv) stx.getKind
let macros := macroAttribute.getEntries (← getEnv) stx.getKind
if evalFns.isEmpty && macros.isEmpty then
throwErrorAt stx "tactic '{stx.getKind}' has not been implemented"
let s ← Tactic.saveState
expandEval s macros evalFns #[]
| .missing => pure ()
| _ => throwError m!"unexpected tactic{indentD stx}"
where
throwExs (failures : Array EvalTacticFailure) : TacticM Unit := do
if let some fail := failures[0]? then
-- Recall that `failures[0]` is the highest priority evalFn/macro
fail.state.restore (restoreInfo := true)
throw fail.exception -- (*)
else
throwErrorAt stx "unexpected syntax {indentD stx}"
@[inline] handleEx (s : SavedState) (failures : Array EvalTacticFailure) (ex : Exception) (k : Array EvalTacticFailure → TacticM Unit) := do
match ex with
| .error .. =>
trace[Elab.tactic.backtrack] ex.toMessageData
let failures := failures.push ⟨ex, ← Tactic.saveState⟩
s.restore (restoreInfo := true); k failures
| .internal id _ =>
if id == unsupportedSyntaxExceptionId then
-- We do not store `unsupportedSyntaxExceptionId`, see throwExs
s.restore (restoreInfo := true); k failures
else if id == abortTacticExceptionId then
for msg in (← Core.getMessageLog).toList do
trace[Elab.tactic.backtrack] msg.data
let failures := failures.push ⟨ex, ← Tactic.saveState⟩
s.restore (restoreInfo := true); k failures
else
throw ex -- (*)
expandEval (s : SavedState) (macros : List _) (evalFns : List _) (failures : Array EvalTacticFailure) : TacticM Unit :=
match macros with
| [] => eval s evalFns failures
| m :: ms =>
try
withReader ({ · with elaborator := m.declName }) do
withTacticInfoContext stx do
let stx' ← adaptMacro m.value stx
evalTactic stx'
catch ex => handleEx s failures ex (expandEval s ms evalFns)
eval (s : SavedState) (evalFns : List _) (failures : Array EvalTacticFailure) : TacticM Unit := do
match evalFns with
| [] => throwExs failures
| evalFn::evalFns => do
try
withReader ({ · with elaborator := evalFn.declName }) <| withTacticInfoContext stx <| evalFn.value stx
catch ex => handleEx s failures ex (eval s evalFns)
def throwNoGoalsToBeSolved : TacticM α :=
throwError "no goals to be solved"
def done : TacticM Unit := do
let gs ← getUnsolvedGoals
unless gs.isEmpty do
Term.reportUnsolvedGoals gs
throwAbortTactic
def focus (x : TacticM α) : TacticM α := do
let mvarId :: mvarIds ← getUnsolvedGoals | throwNoGoalsToBeSolved
setGoals [mvarId]
let a ← x
let mvarIds' ← getUnsolvedGoals
setGoals (mvarIds' ++ mvarIds)
pure a
def focusAndDone (tactic : TacticM α) : TacticM α :=
focus do
let a ← tactic
done
pure a
/-- Close the main goal using the given tactic. If it fails, log the error and `admit` -/
def closeUsingOrAdmit (tac : TacticM Unit) : TacticM Unit := do
/- Important: we must define `closeUsingOrAdmit` before we define
the instance `MonadExcept` for `TacticM` since it backtracks the state including error messages. -/
let mvarId :: mvarIds ← getUnsolvedGoals | throwNoGoalsToBeSolved
try
focusAndDone tac
catch ex =>
if (← read).recover then
logException ex
admitGoal mvarId
setGoals mvarIds
else
throw ex
instance : MonadBacktrack SavedState TacticM where
saveState := Tactic.saveState
restoreState b := b.restore
@[inline] protected def tryCatch {α} (x : TacticM α) (h : Exception → TacticM α) : TacticM α := do
let b ← saveState
try x catch ex => b.restore; h ex
instance : MonadExcept Exception TacticM where
throw := throw
tryCatch := Tactic.tryCatch
/-- Execute `x` with error recovery disabled -/
def withoutRecover (x : TacticM α) : TacticM α :=
withReader (fun ctx => { ctx with recover := false }) x
@[inline] protected def orElse (x : TacticM α) (y : Unit → TacticM α) : TacticM α := do
try withoutRecover x catch _ => y ()
instance : OrElse (TacticM α) where
orElse := Tactic.orElse
instance : Alternative TacticM where
failure := fun {_} => throwError "failed"
orElse := Tactic.orElse
/--
Save the current tactic state for a token `stx`.
This method is a no-op if `stx` has no position information.
We use this method to save the tactic state at punctuation such as `;`
-/
def saveTacticInfoForToken (stx : Syntax) : TacticM Unit := do
unless stx.getPos?.isNone do
withTacticInfoContext stx (pure ())
/-- Elaborate `x` with `stx` on the macro stack -/
@[inline]
def withMacroExpansion (beforeStx afterStx : Syntax) (x : TacticM α) : TacticM α :=
withMacroExpansionInfo beforeStx afterStx do
withTheReader Term.Context (fun ctx => { ctx with macroStack := { before := beforeStx, after := afterStx } :: ctx.macroStack }) x
/-- Adapt a syntax transformation to a regular tactic evaluator. -/
def adaptExpander (exp : Syntax → TacticM Syntax) : Tactic := fun stx => do
let stx' ← exp stx
withMacroExpansion stx stx' $ evalTactic stx'
/-- Add the given goals at the end of the current goals collection. -/
def appendGoals (mvarIds : List MVarId) : TacticM Unit :=
modify fun s => { s with goals := s.goals ++ mvarIds }
/-- Discard the first goal and replace it by the given list of goals,
keeping the other goals. -/
def replaceMainGoal (mvarIds : List MVarId) : TacticM Unit := do
let (_ :: mvarIds') ← getGoals | throwNoGoalsToBeSolved
modify fun _ => { goals := mvarIds ++ mvarIds' }
/-- Return the first goal. -/
def getMainGoal : TacticM MVarId := do
loop (← getGoals)
where
loop : List MVarId → TacticM MVarId
| [] => throwNoGoalsToBeSolved
| mvarId :: mvarIds => do
if (← mvarId.isAssigned) then
loop mvarIds
else
setGoals (mvarId :: mvarIds)
return mvarId
/-- Return the main goal metavariable declaration. -/
def getMainDecl : TacticM MetavarDecl := do
(← getMainGoal).getDecl
/-- Return the main goal tag. -/
def getMainTag : TacticM Name :=
return (← getMainDecl).userName
/-- Return expected type for the main goal. -/
def getMainTarget : TacticM Expr := do
instantiateMVars (← getMainDecl).type
/-- Execute `x` using the main goal local context and instances -/
def withMainContext (x : TacticM α) : TacticM α := do
(← getMainGoal).withContext x
/-- Evaluate `tac` at `mvarId`, and return the list of resulting subgoals. -/
def evalTacticAt (tac : Syntax) (mvarId : MVarId) : TacticM (List MVarId) := do
let gs ← getGoals
try
setGoals [mvarId]
evalTactic tac
pruneSolvedGoals
getGoals
finally
setGoals gs
def ensureHasNoMVars (e : Expr) : TacticM Unit := do
let e ← instantiateMVars e
let pendingMVars ← getMVars e
discard <| Term.logUnassignedUsingErrorInfos pendingMVars
if e.hasExprMVar then
throwError "tactic failed, resulting expression contains metavariables{indentExpr e}"
/-- Close main goal using the given expression. If `checkUnassigned == true`, then `val` must not contain unassigned metavariables. -/
def closeMainGoal (val : Expr) (checkUnassigned := true): TacticM Unit := do
if checkUnassigned then
ensureHasNoMVars val
(← getMainGoal).assign val
replaceMainGoal []
@[inline] def liftMetaMAtMain (x : MVarId → MetaM α) : TacticM α := do
withMainContext do x (← getMainGoal)
@[inline] def liftMetaTacticAux (tac : MVarId → MetaM (α × List MVarId)) : TacticM α := do
withMainContext do
let (a, mvarIds) ← tac (← getMainGoal)
replaceMainGoal mvarIds
pure a
/-- Get the mvarid of the main goal, run the given `tactic`,
then set the new goals to be the resulting goal list.-/
@[inline] def liftMetaTactic (tactic : MVarId → MetaM (List MVarId)) : TacticM Unit :=
liftMetaTacticAux fun mvarId => do
let gs ← tactic mvarId
pure ((), gs)
@[inline] def liftMetaTactic1 (tactic : MVarId → MetaM (Option MVarId)) : TacticM Unit :=
withMainContext do
if let some mvarId ← tactic (← getMainGoal) then
replaceMainGoal [mvarId]
else
replaceMainGoal []
def tryTactic? (tactic : TacticM α) : TacticM (Option α) := do
try
pure (some (← tactic))
catch _ =>
pure none
def tryTactic (tactic : TacticM α) : TacticM Bool := do
try
discard tactic
pure true
catch _ =>
pure false
/--
Use `parentTag` to tag untagged goals at `newGoals`.
If there are multiple new untagged goals, they are named using `<parentTag>.<newSuffix>_<idx>` where `idx > 0`.
If there is only one new untagged goal, then we just use `parentTag` -/
def tagUntaggedGoals (parentTag : Name) (newSuffix : Name) (newGoals : List MVarId) : TacticM Unit := do
let mctx ← getMCtx
let mut numAnonymous := 0
for g in newGoals do
if mctx.isAnonymousMVar g then
numAnonymous := numAnonymous + 1
modifyMCtx fun mctx => Id.run do
let mut mctx := mctx
let mut idx := 1
for g in newGoals do
if mctx.isAnonymousMVar g then
if numAnonymous == 1 then
mctx := mctx.setMVarUserName g parentTag
else
mctx := mctx.setMVarUserName g (parentTag ++ newSuffix.appendIndexAfter idx)
idx := idx + 1
pure mctx
/- Recall that `ident' := ident <|> Term.hole` -/
def getNameOfIdent' (id : Syntax) : Name :=
if id.isIdent then id.getId else `_
/--
Use position of `=> $body` for error messages.
If there is a line break before `body`, the message will be displayed on `=>` only,
but the "full range" for the info view will still include `body`. -/
def withCaseRef [Monad m] [MonadRef m] (arrow body : Syntax) (x : m α) : m α :=
withRef (mkNullNode #[arrow, body]) x
builtin_initialize registerTraceClass `Elab.tactic
builtin_initialize registerTraceClass `Elab.tactic.backtrack
end Lean.Elab.Tactic
|
0dbbd538f3324d4c03bdfb81557e3ad97c1209cb | 4d2583807a5ac6caaffd3d7a5f646d61ca85d532 | /src/category_theory/adjunction/basic.lean | 542cb3ce357caebb6f5d84cdee0e4dd96d09568f | [
"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 | 19,206 | lean | /-
Copyright (c) 2019 Reid Barton. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Reid Barton, Johan Commelin, Bhavik Mehta
-/
import category_theory.equivalence
/-!
# Adjunctions between functors
`F ⊣ G` represents the data of an adjunction between two functors
`F : C ⥤ D` and `G : D ⥤ C`. `F` is the left adjoint and `G` is the right adjoint.
We provide various useful constructors:
* `mk_of_hom_equiv`
* `mk_of_unit_counit`
* `left_adjoint_of_equiv` / `right_adjoint_of equiv`
construct a left/right adjoint of a given functor given the action on objects and
the relevant equivalence of morphism spaces.
* `adjunction_of_equiv_left` / `adjunction_of_equiv_right` witness that these constructions
give adjunctions.
There are also typeclasses `is_left_adjoint` / `is_right_adjoint`, carrying data witnessing
that a given functor is a left or right adjoint.
Given `[is_left_adjoint F]`, a right adjoint of `F` can be constructed as `right_adjoint F`.
`adjunction.comp` composes adjunctions.
`to_equivalence` upgrades an adjunction to an equivalence,
given witnesses that the unit and counit are pointwise isomorphisms.
Conversely `equivalence.to_adjunction` recovers the underlying adjunction from an equivalence.
-/
namespace category_theory
open category
-- declare the `v`'s first; see `category_theory.category` for an explanation
universes v₁ v₂ v₃ u₁ u₂ u₃
local attribute [elab_simple] whisker_left whisker_right
variables {C : Type u₁} [category.{v₁} C] {D : Type u₂} [category.{v₂} D]
/--
`F ⊣ G` represents the data of an adjunction between two functors
`F : C ⥤ D` and `G : D ⥤ C`. `F` is the left adjoint and `G` is the right adjoint.
To construct an `adjunction` between two functors, it's often easier to instead use the
constructors `mk_of_hom_equiv` or `mk_of_unit_counit`. To construct a left adjoint,
there are also constructors `left_adjoint_of_equiv` and `adjunction_of_equiv_left` (as
well as their duals) which can be simpler in practice.
Uniqueness of adjoints is shown in `category_theory.adjunction.opposites`.
See https://stacks.math.columbia.edu/tag/0037.
-/
structure adjunction (F : C ⥤ D) (G : D ⥤ C) :=
(hom_equiv : Π (X Y), (F.obj X ⟶ Y) ≃ (X ⟶ G.obj Y))
(unit : 𝟭 C ⟶ F.comp G)
(counit : G.comp F ⟶ 𝟭 D)
(hom_equiv_unit' : Π {X Y f}, (hom_equiv X Y) f = (unit : _ ⟶ _).app X ≫ G.map f . obviously)
(hom_equiv_counit' : Π {X Y g}, (hom_equiv X Y).symm g = F.map g ≫ counit.app Y . obviously)
infix ` ⊣ `:15 := adjunction
/-- A class giving a chosen right adjoint to the functor `left`. -/
class is_left_adjoint (left : C ⥤ D) :=
(right : D ⥤ C)
(adj : left ⊣ right)
/-- A class giving a chosen left adjoint to the functor `right`. -/
class is_right_adjoint (right : D ⥤ C) :=
(left : C ⥤ D)
(adj : left ⊣ right)
/-- Extract the left adjoint from the instance giving the chosen adjoint. -/
def left_adjoint (R : D ⥤ C) [is_right_adjoint R] : C ⥤ D :=
is_right_adjoint.left R
/-- Extract the right adjoint from the instance giving the chosen adjoint. -/
def right_adjoint (L : C ⥤ D) [is_left_adjoint L] : D ⥤ C :=
is_left_adjoint.right L
/-- The adjunction associated to a functor known to be a left adjoint. -/
def adjunction.of_left_adjoint (left : C ⥤ D) [is_left_adjoint left] :
adjunction left (right_adjoint left) :=
is_left_adjoint.adj
/-- The adjunction associated to a functor known to be a right adjoint. -/
def adjunction.of_right_adjoint (right : C ⥤ D) [is_right_adjoint right] :
adjunction (left_adjoint right) right :=
is_right_adjoint.adj
namespace adjunction
restate_axiom hom_equiv_unit'
restate_axiom hom_equiv_counit'
attribute [simp, priority 10] hom_equiv_unit hom_equiv_counit
section
variables {F : C ⥤ D} {G : D ⥤ C} (adj : F ⊣ G) {X' X : C} {Y Y' : D}
@[simp, priority 10] lemma hom_equiv_naturality_left_symm (f : X' ⟶ X) (g : X ⟶ G.obj Y) :
(adj.hom_equiv X' Y).symm (f ≫ g) = F.map f ≫ (adj.hom_equiv X Y).symm g :=
by rw [hom_equiv_counit, F.map_comp, assoc, adj.hom_equiv_counit.symm]
@[simp] lemma hom_equiv_naturality_left (f : X' ⟶ X) (g : F.obj X ⟶ Y) :
(adj.hom_equiv X' Y) (F.map f ≫ g) = f ≫ (adj.hom_equiv X Y) g :=
by rw [← equiv.eq_symm_apply]; simp [-hom_equiv_unit]
@[simp, priority 10] lemma hom_equiv_naturality_right (f : F.obj X ⟶ Y) (g : Y ⟶ Y') :
(adj.hom_equiv X Y') (f ≫ g) = (adj.hom_equiv X Y) f ≫ G.map g :=
by rw [hom_equiv_unit, G.map_comp, ← assoc, ←hom_equiv_unit]
@[simp] lemma hom_equiv_naturality_right_symm (f : X ⟶ G.obj Y) (g : Y ⟶ Y') :
(adj.hom_equiv X Y').symm (f ≫ G.map g) = (adj.hom_equiv X Y).symm f ≫ g :=
by rw [equiv.symm_apply_eq]; simp [-hom_equiv_counit]
@[simp] lemma left_triangle :
(whisker_right adj.unit F) ≫ (whisker_left F adj.counit) = nat_trans.id _ :=
begin
ext, dsimp,
erw [← adj.hom_equiv_counit, equiv.symm_apply_eq, adj.hom_equiv_unit],
simp
end
@[simp] lemma right_triangle :
(whisker_left G adj.unit) ≫ (whisker_right adj.counit G) = nat_trans.id _ :=
begin
ext, dsimp,
erw [← adj.hom_equiv_unit, ← equiv.eq_symm_apply, adj.hom_equiv_counit],
simp
end
@[simp, reassoc] lemma left_triangle_components :
F.map (adj.unit.app X) ≫ adj.counit.app (F.obj X) = 𝟙 (F.obj X) :=
congr_arg (λ (t : nat_trans _ (𝟭 C ⋙ F)), t.app X) adj.left_triangle
@[simp, reassoc] lemma right_triangle_components {Y : D} :
adj.unit.app (G.obj Y) ≫ G.map (adj.counit.app Y) = 𝟙 (G.obj Y) :=
congr_arg (λ (t : nat_trans _ (G ⋙ 𝟭 C)), t.app Y) adj.right_triangle
@[simp, reassoc] lemma counit_naturality {X Y : D} (f : X ⟶ Y) :
F.map (G.map f) ≫ (adj.counit).app Y = (adj.counit).app X ≫ f :=
adj.counit.naturality f
@[simp, reassoc] lemma unit_naturality {X Y : C} (f : X ⟶ Y) :
(adj.unit).app X ≫ G.map (F.map f) = f ≫ (adj.unit).app Y :=
(adj.unit.naturality f).symm
lemma hom_equiv_apply_eq {A : C} {B : D} (f : F.obj A ⟶ B) (g : A ⟶ G.obj B) :
adj.hom_equiv A B f = g ↔ f = (adj.hom_equiv A B).symm g :=
⟨λ h, by {cases h, simp}, λ h, by {cases h, simp}⟩
lemma eq_hom_equiv_apply {A : C} {B : D} (f : F.obj A ⟶ B) (g : A ⟶ G.obj B) :
g = adj.hom_equiv A B f ↔ (adj.hom_equiv A B).symm g = f :=
⟨λ h, by {cases h, simp}, λ h, by {cases h, simp}⟩
end
end adjunction
namespace adjunction
/--
This is an auxiliary data structure useful for constructing adjunctions.
See `adjunction.mk_of_hom_equiv`.
This structure won't typically be used anywhere else.
-/
@[nolint has_inhabited_instance]
structure core_hom_equiv (F : C ⥤ D) (G : D ⥤ C) :=
(hom_equiv : Π (X Y), (F.obj X ⟶ Y) ≃ (X ⟶ G.obj Y))
(hom_equiv_naturality_left_symm' : Π {X' X Y} (f : X' ⟶ X) (g : X ⟶ G.obj Y),
(hom_equiv X' Y).symm (f ≫ g) = F.map f ≫ (hom_equiv X Y).symm g . obviously)
(hom_equiv_naturality_right' : Π {X Y Y'} (f : F.obj X ⟶ Y) (g : Y ⟶ Y'),
(hom_equiv X Y') (f ≫ g) = (hom_equiv X Y) f ≫ G.map g . obviously)
namespace core_hom_equiv
restate_axiom hom_equiv_naturality_left_symm'
restate_axiom hom_equiv_naturality_right'
attribute [simp, priority 10] hom_equiv_naturality_left_symm hom_equiv_naturality_right
variables {F : C ⥤ D} {G : D ⥤ C} (adj : core_hom_equiv F G) {X' X : C} {Y Y' : D}
@[simp] lemma hom_equiv_naturality_left (f : X' ⟶ X) (g : F.obj X ⟶ Y) :
(adj.hom_equiv X' Y) (F.map f ≫ g) = f ≫ (adj.hom_equiv X Y) g :=
by rw [← equiv.eq_symm_apply]; simp
@[simp] lemma hom_equiv_naturality_right_symm (f : X ⟶ G.obj Y) (g : Y ⟶ Y') :
(adj.hom_equiv X Y').symm (f ≫ G.map g) = (adj.hom_equiv X Y).symm f ≫ g :=
by rw [equiv.symm_apply_eq]; simp
end core_hom_equiv
/--
This is an auxiliary data structure useful for constructing adjunctions.
See `adjunction.mk_of_unit_counit`.
This structure won't typically be used anywhere else.
-/
@[nolint has_inhabited_instance]
structure core_unit_counit (F : C ⥤ D) (G : D ⥤ C) :=
(unit : 𝟭 C ⟶ F.comp G)
(counit : G.comp F ⟶ 𝟭 D)
(left_triangle' : whisker_right unit F ≫ (functor.associator F G F).hom ≫ whisker_left F counit =
nat_trans.id (𝟭 C ⋙ F) . obviously)
(right_triangle' : whisker_left G unit ≫ (functor.associator G F G).inv ≫ whisker_right counit G =
nat_trans.id (G ⋙ 𝟭 C) . obviously)
namespace core_unit_counit
restate_axiom left_triangle'
restate_axiom right_triangle'
attribute [simp] left_triangle right_triangle
end core_unit_counit
variables {F : C ⥤ D} {G : D ⥤ C}
/-- Construct an adjunction between `F` and `G` out of a natural bijection between each
`F.obj X ⟶ Y` and `X ⟶ G.obj Y`. -/
@[simps]
def mk_of_hom_equiv (adj : core_hom_equiv F G) : F ⊣ G :=
{ unit :=
{ app := λ X, (adj.hom_equiv X (F.obj X)) (𝟙 (F.obj X)),
naturality' :=
begin
intros,
erw [← adj.hom_equiv_naturality_left, ← adj.hom_equiv_naturality_right],
dsimp, simp -- See note [dsimp, simp].
end },
counit :=
{ app := λ Y, (adj.hom_equiv _ _).inv_fun (𝟙 (G.obj Y)),
naturality' :=
begin
intros,
erw [← adj.hom_equiv_naturality_left_symm, ← adj.hom_equiv_naturality_right_symm],
dsimp, simp
end },
hom_equiv_unit' := λ X Y f, by erw [← adj.hom_equiv_naturality_right]; simp,
hom_equiv_counit' := λ X Y f, by erw [← adj.hom_equiv_naturality_left_symm]; simp,
.. adj }
/-- Construct an adjunction between functors `F` and `G` given a unit and counit for the adjunction
satisfying the triangle identities. -/
@[simps]
def mk_of_unit_counit (adj : core_unit_counit F G) : F ⊣ G :=
{ hom_equiv := λ X Y,
{ to_fun := λ f, adj.unit.app X ≫ G.map f,
inv_fun := λ g, F.map g ≫ adj.counit.app Y,
left_inv := λ f, begin
change F.map (_ ≫ _) ≫ _ = _,
rw [F.map_comp, assoc, ←functor.comp_map, adj.counit.naturality, ←assoc],
convert id_comp f,
have t := congr_arg (λ t : nat_trans _ _, t.app _) adj.left_triangle,
dsimp at t,
simp only [id_comp] at t,
exact t,
end,
right_inv := λ g, begin
change _ ≫ G.map (_ ≫ _) = _,
rw [G.map_comp, ←assoc, ←functor.comp_map, ←adj.unit.naturality, assoc],
convert comp_id g,
have t := congr_arg (λ t : nat_trans _ _, t.app _) adj.right_triangle,
dsimp at t,
simp only [id_comp] at t,
exact t,
end },
.. adj }
/-- The adjunction between the identity functor on a category and itself. -/
def id : 𝟭 C ⊣ 𝟭 C :=
{ hom_equiv := λ X Y, equiv.refl _,
unit := 𝟙 _,
counit := 𝟙 _ }
-- Satisfy the inhabited linter.
instance : inhabited (adjunction (𝟭 C) (𝟭 C)) := ⟨id⟩
/-- If F and G are naturally isomorphic functors, establish an equivalence of hom-sets. -/
@[simps]
def equiv_homset_left_of_nat_iso
{F F' : C ⥤ D} (iso : F ≅ F') {X : C} {Y : D} :
(F.obj X ⟶ Y) ≃ (F'.obj X ⟶ Y) :=
{ to_fun := λ f, iso.inv.app _ ≫ f,
inv_fun := λ g, iso.hom.app _ ≫ g,
left_inv := λ f, by simp,
right_inv := λ g, by simp }
/-- If G and H are naturally isomorphic functors, establish an equivalence of hom-sets. -/
@[simps]
def equiv_homset_right_of_nat_iso
{G G' : D ⥤ C} (iso : G ≅ G') {X : C} {Y : D} :
(X ⟶ G.obj Y) ≃ (X ⟶ G'.obj Y) :=
{ to_fun := λ f, f ≫ iso.hom.app _,
inv_fun := λ g, g ≫ iso.inv.app _,
left_inv := λ f, by simp,
right_inv := λ g, by simp }
/-- Transport an adjunction along an natural isomorphism on the left. -/
def of_nat_iso_left
{F G : C ⥤ D} {H : D ⥤ C} (adj : F ⊣ H) (iso : F ≅ G) :
G ⊣ H :=
adjunction.mk_of_hom_equiv
{ hom_equiv := λ X Y, (equiv_homset_left_of_nat_iso iso.symm).trans (adj.hom_equiv X Y) }
/-- Transport an adjunction along an natural isomorphism on the right. -/
def of_nat_iso_right
{F : C ⥤ D} {G H : D ⥤ C} (adj : F ⊣ G) (iso : G ≅ H) :
F ⊣ H :=
adjunction.mk_of_hom_equiv
{ hom_equiv := λ X Y, (adj.hom_equiv X Y).trans (equiv_homset_right_of_nat_iso iso) }
/-- Transport being a right adjoint along a natural isomorphism. -/
def right_adjoint_of_nat_iso {F G : C ⥤ D} (h : F ≅ G) [r : is_right_adjoint F] :
is_right_adjoint G :=
{ left := r.left,
adj := of_nat_iso_right r.adj h }
/-- Transport being a left adjoint along a natural isomorphism. -/
def left_adjoint_of_nat_iso {F G : C ⥤ D} (h : F ≅ G) [r : is_left_adjoint F] : is_left_adjoint G :=
{ right := r.right,
adj := of_nat_iso_left r.adj h }
section
variables {E : Type u₃} [ℰ : category.{v₃} E] (H : D ⥤ E) (I : E ⥤ D)
/--
Composition of adjunctions.
See https://stacks.math.columbia.edu/tag/0DV0.
-/
def comp (adj₁ : F ⊣ G) (adj₂ : H ⊣ I) : F ⋙ H ⊣ I ⋙ G :=
{ hom_equiv := λ X Z, equiv.trans (adj₂.hom_equiv _ _) (adj₁.hom_equiv _ _),
unit := adj₁.unit ≫
(whisker_left F $ whisker_right adj₂.unit G) ≫ (functor.associator _ _ _).inv,
counit := (functor.associator _ _ _).hom ≫
(whisker_left I $ whisker_right adj₁.counit H) ≫ adj₂.counit }
/-- If `F` and `G` are left adjoints then `F ⋙ G` is a left adjoint too. -/
instance left_adjoint_of_comp {E : Type u₃} [ℰ : category.{v₃} E] (F : C ⥤ D) (G : D ⥤ E)
[Fl : is_left_adjoint F] [Gl : is_left_adjoint G] : is_left_adjoint (F ⋙ G) :=
{ right := Gl.right ⋙ Fl.right,
adj := comp _ _ Fl.adj Gl.adj }
/-- If `F` and `G` are right adjoints then `F ⋙ G` is a right adjoint too. -/
instance right_adjoint_of_comp {E : Type u₃} [ℰ : category.{v₃} E] {F : C ⥤ D} {G : D ⥤ E}
[Fr : is_right_adjoint F] [Gr : is_right_adjoint G] : is_right_adjoint (F ⋙ G) :=
{ left := Gr.left ⋙ Fr.left,
adj := comp _ _ Gr.adj Fr.adj }
end
section construct_left
-- Construction of a left adjoint. In order to construct a left
-- adjoint to a functor G : D → C, it suffices to give the object part
-- of a functor F : C → D together with isomorphisms Hom(FX, Y) ≃
-- Hom(X, GY) natural in Y. The action of F on morphisms can be
-- constructed from this data.
variables {F_obj : C → D} {G}
variables (e : Π X Y, (F_obj X ⟶ Y) ≃ (X ⟶ G.obj Y))
variables (he : ∀ X Y Y' g h, e X Y' (h ≫ g) = e X Y h ≫ G.map g)
include he
private lemma he' {X Y Y'} (f g) : (e X Y').symm (f ≫ G.map g) = (e X Y).symm f ≫ g :=
by intros; rw [equiv.symm_apply_eq, he]; simp
/-- Construct a left adjoint functor to `G`, given the functor's value on objects `F_obj` and
a bijection `e` between `F_obj X ⟶ Y` and `X ⟶ G.obj Y` satisfying a naturality law
`he : ∀ X Y Y' g h, e X Y' (h ≫ g) = e X Y h ≫ G.map g`.
Dual to `right_adjoint_of_equiv`. -/
@[simps]
def left_adjoint_of_equiv : C ⥤ D :=
{ obj := F_obj,
map := λ X X' f, (e X (F_obj X')).symm (f ≫ e X' (F_obj X') (𝟙 _)),
map_comp' := λ X X' X'' f f', begin
rw [equiv.symm_apply_eq, he, equiv.apply_symm_apply],
conv { to_rhs, rw [assoc, ←he, id_comp, equiv.apply_symm_apply] },
simp
end }
/-- Show that the functor given by `left_adjoint_of_equiv` is indeed left adjoint to `G`. Dual
to `adjunction_of_equiv_right`. -/
@[simps]
def adjunction_of_equiv_left : left_adjoint_of_equiv e he ⊣ G :=
mk_of_hom_equiv
{ hom_equiv := e,
hom_equiv_naturality_left_symm' :=
begin
intros,
erw [← he' e he, ← equiv.apply_eq_iff_eq],
simp [(he _ _ _ _ _).symm]
end }
end construct_left
section construct_right
-- Construction of a right adjoint, analogous to the above.
variables {F} {G_obj : D → C}
variables (e : Π X Y, (F.obj X ⟶ Y) ≃ (X ⟶ G_obj Y))
variables (he : ∀ X' X Y f g, e X' Y (F.map f ≫ g) = f ≫ e X Y g)
include he
private lemma he' {X' X Y} (f g) : F.map f ≫ (e X Y).symm g = (e X' Y).symm (f ≫ g) :=
by intros; rw [equiv.eq_symm_apply, he]; simp
/-- Construct a right adjoint functor to `F`, given the functor's value on objects `G_obj` and
a bijection `e` between `F.obj X ⟶ Y` and `X ⟶ G_obj Y` satisfying a naturality law
`he : ∀ X Y Y' g h, e X' Y (F.map f ≫ g) = f ≫ e X Y g`.
Dual to `left_adjoint_of_equiv`. -/
@[simps]
def right_adjoint_of_equiv : D ⥤ C :=
{ obj := G_obj,
map := λ Y Y' g, (e (G_obj Y) Y') ((e (G_obj Y) Y).symm (𝟙 _) ≫ g),
map_comp' := λ Y Y' Y'' g g', begin
rw [← equiv.eq_symm_apply, ← he' e he, equiv.symm_apply_apply],
conv { to_rhs, rw [← assoc, he' e he, comp_id, equiv.symm_apply_apply] },
simp
end }
/-- Show that the functor given by `right_adjoint_of_equiv` is indeed right adjoint to `F`. Dual
to `adjunction_of_equiv_left`. -/
@[simps]
def adjunction_of_equiv_right : F ⊣ right_adjoint_of_equiv e he :=
mk_of_hom_equiv
{ hom_equiv := e,
hom_equiv_naturality_left_symm' := by intros; rw [equiv.symm_apply_eq, he]; simp,
hom_equiv_naturality_right' :=
begin
intros X Y Y' g h,
erw [←he, equiv.apply_eq_iff_eq, ←assoc, he' e he, comp_id, equiv.symm_apply_apply]
end }
end construct_right
/--
If the unit and counit of a given adjunction are (pointwise) isomorphisms, then we can upgrade the
adjunction to an equivalence.
-/
@[simps]
noncomputable
def to_equivalence (adj : F ⊣ G) [∀ X, is_iso (adj.unit.app X)] [∀ Y, is_iso (adj.counit.app Y)] :
C ≌ D :=
{ functor := F,
inverse := G,
unit_iso := nat_iso.of_components (λ X, as_iso (adj.unit.app X)) (by simp),
counit_iso := nat_iso.of_components (λ Y, as_iso (adj.counit.app Y)) (by simp) }
/--
If the unit and counit for the adjunction corresponding to a right adjoint functor are (pointwise)
isomorphisms, then the functor is an equivalence of categories.
-/
@[simps]
noncomputable
def is_right_adjoint_to_is_equivalence [is_right_adjoint G]
[∀ X, is_iso ((adjunction.of_right_adjoint G).unit.app X)]
[∀ Y, is_iso ((adjunction.of_right_adjoint G).counit.app Y)] :
is_equivalence G :=
is_equivalence.of_equivalence_inverse (adjunction.of_right_adjoint G).to_equivalence
end adjunction
open adjunction
namespace equivalence
/-- The adjunction given by an equivalence of categories. (To obtain the opposite adjunction,
simply use `e.symm.to_adjunction`. -/
def to_adjunction (e : C ≌ D) : e.functor ⊣ e.inverse :=
mk_of_unit_counit ⟨e.unit, e.counit,
by { ext, dsimp, simp only [id_comp], exact e.functor_unit_comp _, },
by { ext, dsimp, simp only [id_comp], exact e.unit_inverse_comp _, }⟩
end equivalence
namespace functor
/-- An equivalence `E` is left adjoint to its inverse. -/
def adjunction (E : C ⥤ D) [is_equivalence E] : E ⊣ E.inv :=
(E.as_equivalence).to_adjunction
/-- If `F` is an equivalence, it's a left adjoint. -/
@[priority 10]
instance left_adjoint_of_equivalence {F : C ⥤ D} [is_equivalence F] : is_left_adjoint F :=
{ right := _,
adj := functor.adjunction F }
@[simp]
lemma right_adjoint_of_is_equivalence {F : C ⥤ D} [is_equivalence F] : right_adjoint F = inv F :=
rfl
/-- If `F` is an equivalence, it's a right adjoint. -/
@[priority 10]
instance right_adjoint_of_equivalence {F : C ⥤ D} [is_equivalence F] : is_right_adjoint F :=
{ left := _,
adj := functor.adjunction F.inv }
@[simp]
lemma left_adjoint_of_is_equivalence {F : C ⥤ D} [is_equivalence F] : left_adjoint F = inv F :=
rfl
end functor
end category_theory
|
789fd613cb877c8137df65066d23f9c92ea1d722 | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/data/complex/is_R_or_C.lean | 1c15c35e76caef589786bb05697baef009e4999b | [
"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 | 32,041 | 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 data.real.sqrt
import field_theory.tower
import analysis.normed_space.finite_dimension
/-!
# `is_R_or_C`: a typeclass for ℝ or ℂ
This file defines the typeclass `is_R_or_C` intended to have only two instances:
ℝ and ℂ. It is meant for definitions and theorems which hold for both the real and the complex case,
and in particular when the real case follows directly from the complex case by setting `re` to `id`,
`im` to zero and so on. Its API follows closely that of ℂ.
Possible applications include defining inner products and Hilbert spaces for both the real and
complex case. One would produce the definitions and proof for an arbitrary field of this
typeclass, which basically amounts to doing the complex case, and the two cases then fall out
immediately from the two instances of the class.
The instance for `ℝ` is registered in this file.
The instance for `ℂ` is declared in `analysis.complex.basic`.
## Implementation notes
The coercion from reals into an `is_R_or_C` field is done by registering `algebra_map ℝ K` as
a `has_coe_t`. For this to work, we must proceed carefully to avoid problems involving circular
coercions in the case `K=ℝ`; in particular, we cannot use the plain `has_coe` and must set
priorities carefully. This problem was already solved for `ℕ`, and we copy the solution detailed
in `data/nat/cast`. See also Note [coercion into rings] for more details.
In addition, several lemmas need to be set at priority 900 to make sure that they do not override
their counterparts in `complex.lean` (which causes linter errors).
-/
open_locale big_operators
section
local notation `𝓚` := algebra_map ℝ _
/--
This typeclass captures properties shared by ℝ and ℂ, with an API that closely matches that of ℂ.
-/
class is_R_or_C (K : Type*)
extends nondiscrete_normed_field K, normed_algebra ℝ K, complete_space K :=
(re : K →+ ℝ)
(im : K →+ ℝ)
(conj : K →+* K)
(I : K) -- Meant to be set to 0 for K=ℝ
(I_re_ax : re I = 0)
(I_mul_I_ax : I = 0 ∨ I * I = -1)
(re_add_im_ax : ∀ (z : K), 𝓚 (re z) + 𝓚 (im z) * I = z)
(of_real_re_ax : ∀ r : ℝ, re (𝓚 r) = r)
(of_real_im_ax : ∀ r : ℝ, im (𝓚 r) = 0)
(mul_re_ax : ∀ z w : K, re (z * w) = re z * re w - im z * im w)
(mul_im_ax : ∀ z w : K, im (z * w) = re z * im w + im z * re w)
(conj_re_ax : ∀ z : K, re (conj z) = re z)
(conj_im_ax : ∀ z : K, im (conj z) = -(im z))
(conj_I_ax : conj I = -I)
(norm_sq_eq_def_ax : ∀ (z : K), ∥z∥^2 = (re z) * (re z) + (im z) * (im z))
(mul_im_I_ax : ∀ (z : K), (im z) * im I = im z)
(inv_def_ax : ∀ (z : K), z⁻¹ = conj z * 𝓚 ((∥z∥^2)⁻¹))
(div_I_ax : ∀ (z : K), z / I = -(z * I))
end
namespace is_R_or_C
variables {K : Type*} [is_R_or_C K]
local postfix `†`:100 := @is_R_or_C.conj K _
/- The priority must be set at 900 to ensure that coercions are tried in the right order.
See Note [coercion into rings], or `data/nat/cast.lean` for more details. -/
@[priority 900] noncomputable instance algebra_map_coe : has_coe_t ℝ K := ⟨algebra_map ℝ K⟩
lemma of_real_alg (x : ℝ) : (x : K) = x • (1 : K) :=
algebra.algebra_map_eq_smul_one x
lemma algebra_map_eq_of_real : ⇑(algebra_map ℝ K) = coe := rfl
@[simp] lemma re_add_im (z : K) : ((re z) : K) + (im z) * I = z := is_R_or_C.re_add_im_ax z
@[simp, norm_cast] lemma of_real_re : ∀ r : ℝ, re (r : K) = r := is_R_or_C.of_real_re_ax
@[simp, norm_cast] lemma of_real_im : ∀ r : ℝ, im (r : K) = 0 := is_R_or_C.of_real_im_ax
@[simp] lemma mul_re : ∀ z w : K, re (z * w) = re z * re w - im z * im w :=
is_R_or_C.mul_re_ax
@[simp] lemma mul_im : ∀ z w : K, im (z * w) = re z * im w + im z * re w :=
is_R_or_C.mul_im_ax
theorem inv_def (z : K) : z⁻¹ = conj z * ((∥z∥^2)⁻¹:ℝ) :=
is_R_or_C.inv_def_ax z
theorem ext_iff : ∀ {z w : K}, z = w ↔ re z = re w ∧ im z = im w :=
λ z w, { mp := by { rintro rfl, cc },
mpr := by { rintro ⟨h₁,h₂⟩, rw [←re_add_im z, ←re_add_im w, h₁, h₂] } }
theorem ext : ∀ {z w : K}, re z = re w → im z = im w → z = w :=
by { simp_rw ext_iff, cc }
@[simp, norm_cast, priority 900] lemma of_real_zero : ((0 : ℝ) : K) = 0 :=
by rw [of_real_alg, zero_smul]
@[simp] lemma zero_re' : re (0 : K) = (0 : ℝ) := re.map_zero
@[simp, norm_cast, priority 900] lemma of_real_one : ((1 : ℝ) : K) = 1 :=
by rw [of_real_alg, one_smul]
@[simp] lemma one_re : re (1 : K) = 1 := by rw [←of_real_one, of_real_re]
@[simp] lemma one_im : im (1 : K) = 0 := by rw [←of_real_one, of_real_im]
@[simp, norm_cast, priority 900] theorem of_real_inj {z w : ℝ} : (z : K) = (w : K) ↔ z = w :=
{ mp := λ h, by { convert congr_arg re h; simp only [of_real_re] },
mpr := λ h, by rw h }
@[simp] lemma bit0_re (z : K) : re (bit0 z) = bit0 (re z) := by simp [bit0]
@[simp] lemma bit1_re (z : K) : re (bit1 z) = bit1 (re z) :=
by simp only [bit1, add_monoid_hom.map_add, bit0_re, add_right_inj, one_re]
@[simp] lemma bit0_im (z : K) : im (bit0 z) = bit0 (im z) := by simp [bit0]
@[simp] lemma bit1_im (z : K) : im (bit1 z) = bit0 (im z) :=
by simp only [bit1, add_right_eq_self, add_monoid_hom.map_add, bit0_im, one_im]
@[simp, priority 900] theorem of_real_eq_zero {z : ℝ} : (z : K) = 0 ↔ z = 0 :=
by rw [←of_real_zero]; exact of_real_inj
@[simp, norm_cast, priority 900] lemma of_real_add ⦃r s : ℝ⦄ : ((r + s : ℝ) : K) = r + s :=
by { apply (@is_R_or_C.ext_iff K _ ((r + s : ℝ) : K) (r + s)).mpr, simp }
@[simp, norm_cast, priority 900] lemma of_real_bit0 (r : ℝ) : ((bit0 r : ℝ) : K) = bit0 (r : K) :=
ext_iff.2 $ by simp [bit0]
@[simp, norm_cast, priority 900] lemma of_real_bit1 (r : ℝ) : ((bit1 r : ℝ) : K) = bit1 (r : K) :=
ext_iff.2 $ by simp [bit1]
/- Note: This can be proven by `norm_num` once K is proven to be of characteristic zero below. -/
lemma two_ne_zero : (2 : K) ≠ 0 :=
begin
intro h, rw [(show (2 : K) = ((2 : ℝ) : K), by norm_num), ←of_real_zero, of_real_inj] at h,
linarith,
end
@[simp, norm_cast, priority 900] lemma of_real_neg (r : ℝ) : ((-r : ℝ) : K) = -r :=
ext_iff.2 $ by simp
@[simp, norm_cast, priority 900] lemma of_real_mul (r s : ℝ) : ((r * s : ℝ) : K) = r * s :=
ext_iff.2 $ by simp
@[simp, norm_cast] lemma of_real_smul (r x : ℝ) : r • (x : K) = (r : K) * (x : K) :=
by { simp_rw [← smul_eq_mul, of_real_alg r], simp, }
lemma of_real_mul_re (r : ℝ) (z : K) : re (↑r * z) = r * re z :=
by simp only [mul_re, of_real_im, zero_mul, of_real_re, sub_zero]
lemma of_real_mul_im (r : ℝ) (z : K) : im (↑r * z) = r * (im z) :=
by simp only [add_zero, of_real_im, zero_mul, of_real_re, mul_im]
lemma smul_re : ∀ (r : ℝ) (z : K), re (r • z) = r * (re z) :=
λ r z, by { rw algebra.smul_def, apply of_real_mul_re }
lemma smul_im : ∀ (r : ℝ) (z : K), im (r • z) = r * (im z) :=
λ r z, by { rw algebra.smul_def, apply of_real_mul_im }
/-! ### The imaginary unit, `I` -/
/-- The imaginary unit. -/
@[simp] lemma I_re : re (I : K) = 0 := I_re_ax
@[simp] lemma I_im (z : K) : im z * im (I : K) = im z := mul_im_I_ax z
@[simp] lemma I_im' (z : K) : im (I : K) * im z = im z :=
by rw [mul_comm, I_im _]
lemma I_mul_re (z : K) : re (I * z) = - im z :=
by simp only [I_re, zero_sub, I_im', zero_mul, mul_re]
lemma I_mul_I : (I : K) = 0 ∨ (I : K) * I = -1 := I_mul_I_ax
@[simp] lemma conj_re (z : K) : re (conj z) = re z := is_R_or_C.conj_re_ax z
@[simp] lemma conj_im (z : K) : im (conj z) = -(im z) := is_R_or_C.conj_im_ax z
@[simp] lemma conj_I : conj (I : K) = -I := is_R_or_C.conj_I_ax
@[simp] lemma conj_of_real (r : ℝ) : conj (r : K) = (r : K) :=
by { rw ext_iff, simp only [of_real_im, conj_im, eq_self_iff_true, conj_re, and_self, neg_zero] }
@[simp] lemma conj_bit0 (z : K) : conj (bit0 z) = bit0 (conj z) := by simp [bit0, ext_iff]
@[simp] lemma conj_bit1 (z : K) : conj (bit1 z) = bit1 (conj z) := by simp [bit0, ext_iff]
@[simp] lemma conj_neg_I : conj (-I) = (I : K) := by simp [ext_iff]
@[simp] lemma conj_conj (z : K) : conj (conj z) = z := by simp [ext_iff]
lemma conj_involutive : @function.involutive K is_R_or_C.conj := conj_conj
lemma conj_bijective : @function.bijective K K is_R_or_C.conj := conj_involutive.bijective
lemma conj_inj (z w : K) : conj z = conj w ↔ z = w := conj_bijective.1.eq_iff
lemma conj_eq_zero {z : K} : conj z = 0 ↔ z = 0 :=
ring_hom.map_eq_zero conj
lemma conj_eq_re_sub_im (z : K) : conj z = re z - (im z) * I := by { rw ext_iff, simp, }
lemma conj_smul (r : ℝ) (z : K) : conj (r • z) = r • conj z :=
begin
simp_rw conj_eq_re_sub_im,
simp only [smul_re, smul_im, of_real_mul],
rw smul_sub,
simp_rw of_real_alg,
simp,
end
lemma eq_conj_iff_real {z : K} : conj z = z ↔ ∃ r : ℝ, z = (r : K) :=
begin
split,
{ intro h,
suffices : im z = 0,
{ use (re z),
rw ← add_zero (coe _),
convert (re_add_im z).symm, simp [this] },
contrapose! h,
rw ← re_add_im z,
simp only [conj_of_real, ring_hom.map_add, ring_hom.map_mul, conj_I_ax],
rw [add_left_cancel_iff, ext_iff],
simpa [neg_eq_iff_add_eq_zero, add_self_eq_zero] },
{ rintros ⟨r, rfl⟩, apply conj_of_real }
end
variables (K)
/-- Conjugation as a ring equivalence. This is used to convert the inner product into a
sesquilinear product. -/
def conj_to_ring_equiv : K ≃+* Kᵒᵖ :=
{ to_fun := opposite.op ∘ conj,
inv_fun := conj ∘ opposite.unop,
left_inv := λ x, by simp only [conj_conj, function.comp_app, opposite.unop_op],
right_inv := λ x, by simp only [conj_conj, opposite.op_unop, function.comp_app],
map_mul' := λ x y, by simp [mul_comm],
map_add' := λ x y, by simp }
variables {K}
@[simp] lemma ring_equiv_apply {x : K} : (conj_to_ring_equiv K x).unop = x† := rfl
lemma eq_conj_iff_re {z : K} : conj z = z ↔ ((re z) : K) = z :=
eq_conj_iff_real.trans ⟨by rintro ⟨r, rfl⟩; simp, λ h, ⟨_, h.symm⟩⟩
/-- The norm squared function. -/
def norm_sq : monoid_with_zero_hom K ℝ :=
{ to_fun := λ z, re z * re z + im z * im z,
map_zero' := by simp,
map_one' := by simp,
map_mul' := λ z w, by { simp, ring } }
lemma norm_sq_eq_def {z : K} : ∥z∥^2 = (re z) * (re z) + (im z) * (im z) := norm_sq_eq_def_ax z
lemma norm_sq_eq_def' (z : K) : norm_sq z = ∥z∥^2 := by { rw norm_sq_eq_def, refl }
@[simp] lemma norm_sq_of_real (r : ℝ) : ∥(r : K)∥^2 = r * r :=
by simp [norm_sq_eq_def]
lemma norm_sq_zero : norm_sq (0 : K) = 0 := norm_sq.map_zero
lemma norm_sq_one : norm_sq (1 : K) = 1 := norm_sq.map_one
lemma norm_sq_nonneg (z : K) : 0 ≤ norm_sq z :=
add_nonneg (mul_self_nonneg _) (mul_self_nonneg _)
@[simp] lemma norm_sq_eq_zero {z : K} : norm_sq z = 0 ↔ z = 0 :=
by { rw [norm_sq_eq_def'], simp [sq] }
@[simp] lemma norm_sq_pos {z : K} : 0 < norm_sq z ↔ z ≠ 0 :=
by rw [lt_iff_le_and_ne, ne, eq_comm]; simp [norm_sq_nonneg]
@[simp] lemma norm_sq_neg (z : K) : norm_sq (-z) = norm_sq z :=
by simp [norm_sq_eq_def']
@[simp] lemma norm_sq_conj (z : K) : norm_sq (conj z) = norm_sq z := by simp [norm_sq]
@[simp] lemma norm_sq_mul (z w : K) : norm_sq (z * w) = norm_sq z * norm_sq w :=
norm_sq.map_mul z w
lemma norm_sq_add (z w : K) :
norm_sq (z + w) = norm_sq z + norm_sq w + 2 * (re (z * conj w)) :=
by simp [norm_sq, sq]; ring
lemma re_sq_le_norm_sq (z : K) : re z * re z ≤ norm_sq z :=
le_add_of_nonneg_right (mul_self_nonneg _)
lemma im_sq_le_norm_sq (z : K) : im z * im z ≤ norm_sq z :=
le_add_of_nonneg_left (mul_self_nonneg _)
theorem mul_conj (z : K) : z * conj z = ((norm_sq z) : K) :=
by simp [ext_iff, norm_sq, mul_comm, sub_eq_neg_add, add_comm]
theorem add_conj (z : K) : z + conj z = 2 * (re z) :=
by simp [ext_iff, two_mul]
/-- The pseudo-coercion `of_real` as a `ring_hom`. -/
noncomputable def of_real_hom : ℝ →+* K := algebra_map ℝ K
/-- The coercion from reals as a `ring_hom`. -/
noncomputable def coe_hom : ℝ →+* K := ⟨coe, of_real_one, of_real_mul, of_real_zero, of_real_add⟩
@[simp, norm_cast, priority 900] lemma of_real_sub (r s : ℝ) : ((r - s : ℝ) : K) = r - s :=
ext_iff.2 $ by simp
@[simp, norm_cast, priority 900] lemma of_real_pow (r : ℝ) (n : ℕ) : ((r ^ n : ℝ) : K) = r ^ n :=
by induction n; simp [*, of_real_mul, pow_succ]
theorem sub_conj (z : K) : z - conj z = (2 * im z) * I :=
by simp [ext_iff, two_mul, sub_eq_add_neg, add_mul, mul_im_I_ax]
lemma norm_sq_sub (z w : K) : norm_sq (z - w) =
norm_sq z + norm_sq w - 2 * re (z * conj w) :=
by simp [-mul_re, norm_sq_add, add_comm, add_left_comm, sub_eq_add_neg]
lemma sqrt_norm_sq_eq_norm {z : K} : real.sqrt (norm_sq z) = ∥z∥ :=
begin
have h₂ : ∥z∥ = real.sqrt (∥z∥^2) := (real.sqrt_sq (norm_nonneg z)).symm,
rw [h₂],
exact congr_arg real.sqrt (norm_sq_eq_def' z)
end
/-! ### Inversion -/
@[simp] lemma inv_re (z : K) : re (z⁻¹) = re z / norm_sq z :=
by simp [inv_def, norm_sq_eq_def, norm_sq, division_def]
@[simp] lemma inv_im (z : K) : im (z⁻¹) = im (-z) / norm_sq z :=
by simp [inv_def, norm_sq_eq_def, norm_sq, division_def]
@[simp, norm_cast, priority 900] lemma of_real_inv (r : ℝ) : ((r⁻¹ : ℝ) : K) = r⁻¹ :=
begin
rw ext_iff, by_cases r = 0, { simp [h] },
{ simp; field_simp [h, norm_sq] },
end
protected lemma inv_zero : (0⁻¹ : K) = 0 :=
by rw [← of_real_zero, ← of_real_inv, inv_zero]
protected theorem mul_inv_cancel {z : K} (h : z ≠ 0) : z * z⁻¹ = 1 :=
by rw [inv_def, ←mul_assoc, mul_conj, ←of_real_mul, ←norm_sq_eq_def',
mul_inv_cancel (mt norm_sq_eq_zero.1 h), of_real_one]
lemma div_re (z w : K) : re (z / w) = re z * re w / norm_sq w + im z * im w / norm_sq w :=
by simp [div_eq_mul_inv, mul_assoc, sub_eq_add_neg]
lemma div_im (z w : K) : im (z / w) = im z * re w / norm_sq w - re z * im w / norm_sq w :=
by simp [div_eq_mul_inv, mul_assoc, sub_eq_add_neg, add_comm]
@[simp, norm_cast, priority 900] lemma of_real_div (r s : ℝ) : ((r / s : ℝ) : K) = r / s :=
(@is_R_or_C.coe_hom K _).map_div r s
lemma div_re_of_real {z : K} {r : ℝ} : re (z / r) = re z / r :=
begin
by_cases h : r = 0,
{ simp [h, of_real_zero] },
{ change r ≠ 0 at h,
rw [div_eq_mul_inv, ←of_real_inv, div_eq_mul_inv],
simp [norm_sq, div_mul_eq_div_mul_one_div, div_self h] }
end
@[simp, norm_cast, priority 900] lemma of_real_fpow (r : ℝ) (n : ℤ) : ((r ^ n : ℝ) : K) = r ^ n :=
(@is_R_or_C.coe_hom K _).map_fpow r n
lemma I_mul_I_of_nonzero : (I : K) ≠ 0 → (I : K) * I = -1 :=
by { have := I_mul_I_ax, tauto }
@[simp] lemma div_I (z : K) : z / I = -(z * I) :=
begin
by_cases h : (I : K) = 0,
{ simp [h] },
{ field_simp [mul_assoc, I_mul_I_of_nonzero h] }
end
@[simp] lemma inv_I : (I : K)⁻¹ = -I :=
by { by_cases h : (I : K) = 0; field_simp [h] }
@[simp] lemma norm_sq_inv (z : K) : norm_sq z⁻¹ = (norm_sq z)⁻¹ :=
(@norm_sq K _).map_inv' z
@[simp] lemma norm_sq_div (z w : K) : norm_sq (z / w) = norm_sq z / norm_sq w :=
(@norm_sq K _).map_div z w
lemma norm_conj {z : K} : ∥conj z∥ = ∥z∥ :=
by simp only [←sqrt_norm_sq_eq_norm, norm_sq_conj]
lemma conj_inv {z : K} : conj (z⁻¹) = (conj z)⁻¹ :=
by simp only [inv_def, norm_conj, ring_hom.map_mul, conj_of_real]
lemma conj_div {z w : K} : conj (z / w) = (conj z) / (conj w) :=
by rw [div_eq_inv_mul, div_eq_inv_mul, ring_hom.map_mul]; simp only [conj_inv]
/-! ### Cast lemmas -/
@[simp, norm_cast, priority 900] theorem of_real_nat_cast (n : ℕ) : ((n : ℝ) : K) = n :=
of_real_hom.map_nat_cast n
@[simp, norm_cast] lemma nat_cast_re (n : ℕ) : re (n : K) = n :=
by rw [← of_real_nat_cast, of_real_re]
@[simp, norm_cast] lemma nat_cast_im (n : ℕ) : im (n : K) = 0 :=
by rw [← of_real_nat_cast, of_real_im]
@[simp, norm_cast, priority 900] theorem of_real_int_cast (n : ℤ) : ((n : ℝ) : K) = n :=
of_real_hom.map_int_cast n
@[simp, norm_cast] lemma int_cast_re (n : ℤ) : re (n : K) = n :=
by rw [← of_real_int_cast, of_real_re]
@[simp, norm_cast] lemma int_cast_im (n : ℤ) : im (n : K) = 0 :=
by rw [← of_real_int_cast, of_real_im]
@[simp, norm_cast, priority 900] theorem of_real_rat_cast (n : ℚ) : ((n : ℝ) : K) = n :=
(@is_R_or_C.of_real_hom K _).map_rat_cast n
@[simp, norm_cast] lemma rat_cast_re (q : ℚ) : re (q : K) = q :=
by rw [← of_real_rat_cast, of_real_re]
@[simp, norm_cast] lemma rat_cast_im (q : ℚ) : im (q : K) = 0 :=
by rw [← of_real_rat_cast, of_real_im]
/-! ### Characteristic zero -/
-- TODO: I think this can be instance, because it is a `Prop`
/--
ℝ and ℂ are both of characteristic zero.
Note: This is not registered as an instance to avoid having multiple instances on ℝ and ℂ.
-/
lemma char_zero_R_or_C : char_zero K :=
char_zero_of_inj_zero $ λ n h,
by rwa [← of_real_nat_cast, of_real_eq_zero, nat.cast_eq_zero] at h
theorem re_eq_add_conj (z : K) : ↑(re z) = (z + conj z) / 2 :=
begin
haveI : char_zero K := char_zero_R_or_C,
rw [add_conj, mul_div_cancel_left ((re z):K) two_ne_zero'],
end
theorem im_eq_conj_sub (z : K) : ↑(im z) = I * (conj z - z) / 2 :=
begin
rw [← neg_inj, ← of_real_neg, ← I_mul_re, re_eq_add_conj],
simp [mul_add, sub_eq_add_neg, neg_div']
end
/-! ### Absolute value -/
/-- The complex absolute value function, defined as the square root of the norm squared. -/
@[pp_nodot] noncomputable def abs (z : K) : ℝ := (norm_sq z).sqrt
local notation `abs'` := _root_.abs
local notation `absK` := @abs K _
@[simp, norm_cast] lemma abs_of_real (r : ℝ) : absK r = abs' r :=
by simp [abs, norm_sq, norm_sq_of_real, real.sqrt_mul_self_eq_abs]
lemma norm_eq_abs (z : K) : ∥z∥ = absK z := by simp [abs, norm_sq_eq_def']
lemma abs_of_nonneg {r : ℝ} (h : 0 ≤ r) : absK r = r :=
(abs_of_real _).trans (abs_of_nonneg h)
lemma abs_of_nat (n : ℕ) : absK n = n :=
by { rw [← of_real_nat_cast], exact abs_of_nonneg (nat.cast_nonneg n) }
lemma mul_self_abs (z : K) : abs z * abs z = norm_sq z :=
real.mul_self_sqrt (norm_sq_nonneg _)
@[simp] lemma abs_zero : absK 0 = 0 := by simp [abs]
@[simp] lemma abs_one : absK 1 = 1 := by simp [abs]
@[simp] lemma abs_two : absK 2 = 2 :=
calc absK 2 = absK (2 : ℝ) : by rw [of_real_bit0, of_real_one]
... = (2 : ℝ) : abs_of_nonneg (by norm_num)
lemma abs_nonneg (z : K) : 0 ≤ absK z :=
real.sqrt_nonneg _
@[simp] lemma abs_eq_zero {z : K} : absK z = 0 ↔ z = 0 :=
(real.sqrt_eq_zero $ norm_sq_nonneg _).trans norm_sq_eq_zero
lemma abs_ne_zero {z : K} : abs z ≠ 0 ↔ z ≠ 0 :=
not_congr abs_eq_zero
@[simp] lemma abs_conj (z : K) : abs (conj z) = abs z :=
by simp [abs]
@[simp] lemma abs_mul (z w : K) : abs (z * w) = abs z * abs w :=
by rw [abs, norm_sq_mul, real.sqrt_mul (norm_sq_nonneg _)]; refl
lemma abs_re_le_abs (z : K) : abs' (re z) ≤ abs z :=
by rw [mul_self_le_mul_self_iff (_root_.abs_nonneg (re z)) (abs_nonneg _),
abs_mul_abs_self, mul_self_abs];
apply re_sq_le_norm_sq
lemma abs_im_le_abs (z : K) : abs' (im z) ≤ abs z :=
by rw [mul_self_le_mul_self_iff (_root_.abs_nonneg (im z)) (abs_nonneg _),
abs_mul_abs_self, mul_self_abs];
apply im_sq_le_norm_sq
lemma re_le_abs (z : K) : re z ≤ abs z :=
(abs_le.1 (abs_re_le_abs _)).2
lemma im_le_abs (z : K) : im z ≤ abs z :=
(abs_le.1 (abs_im_le_abs _)).2
lemma im_eq_zero_of_le {a : K} (h : abs a ≤ re a) : im a = 0 :=
begin
rw ← zero_eq_mul_self,
have : re a * re a = re a * re a + im a * im a,
{ convert is_R_or_C.mul_self_abs a;
linarith [re_le_abs a] },
linarith
end
lemma re_eq_self_of_le {a : K} (h : abs a ≤ re a) : (re a : K) = a :=
by { rw ← re_add_im a, simp [im_eq_zero_of_le h] }
lemma abs_add (z w : K) : abs (z + w) ≤ abs z + abs w :=
(mul_self_le_mul_self_iff (abs_nonneg _)
(add_nonneg (abs_nonneg _) (abs_nonneg _))).2 $
begin
rw [mul_self_abs, add_mul_self_eq, mul_self_abs, mul_self_abs,
add_right_comm, norm_sq_add, add_le_add_iff_left,
mul_assoc, mul_le_mul_left (@zero_lt_two ℝ _ _)],
simpa [-mul_re] using re_le_abs (z * conj w)
end
instance : is_absolute_value absK :=
{ abv_nonneg := abs_nonneg,
abv_eq_zero := λ _, abs_eq_zero,
abv_add := abs_add,
abv_mul := abs_mul }
open is_absolute_value
@[simp] lemma abs_abs (z : K) : abs' (abs z) = abs z :=
_root_.abs_of_nonneg (abs_nonneg _)
@[simp] lemma abs_pos {z : K} : 0 < abs z ↔ z ≠ 0 := abv_pos abs
@[simp] lemma abs_neg : ∀ z : K, abs (-z) = abs z := abv_neg abs
lemma abs_sub : ∀ z w : K, abs (z - w) = abs (w - z) := abv_sub abs
lemma abs_sub_le : ∀ a b c : K, abs (a - c) ≤ abs (a - b) + abs (b - c) := abv_sub_le abs
@[simp] theorem abs_inv : ∀ z : K, abs z⁻¹ = (abs z)⁻¹ := abv_inv abs
@[simp] theorem abs_div : ∀ z w : K, abs (z / w) = abs z / abs w := abv_div abs
lemma abs_abs_sub_le_abs_sub : ∀ z w : K, abs' (abs z - abs w) ≤ abs (z - w) :=
abs_abv_sub_le_abv_sub abs
lemma abs_re_div_abs_le_one (z : K) : abs' (re z / abs z) ≤ 1 :=
begin
by_cases hz : z = 0,
{ simp [hz, zero_le_one] },
{ simp_rw [_root_.abs_div, abs_abs, div_le_iff (abs_pos.2 hz), one_mul, abs_re_le_abs] }
end
lemma abs_im_div_abs_le_one (z : K) : abs' (im z / abs z) ≤ 1 :=
begin
by_cases hz : z = 0,
{ simp [hz, zero_le_one] },
{ simp_rw [_root_.abs_div, abs_abs, div_le_iff (abs_pos.2 hz), one_mul, abs_im_le_abs] }
end
@[simp, norm_cast] lemma abs_cast_nat (n : ℕ) : abs (n : K) = n :=
by rw [← of_real_nat_cast, abs_of_nonneg (nat.cast_nonneg n)]
lemma norm_sq_eq_abs (x : K) : norm_sq x = abs x ^ 2 :=
by rw [abs, sq, real.mul_self_sqrt (norm_sq_nonneg _)]
lemma re_eq_abs_of_mul_conj (x : K) : re (x * (conj x)) = abs (x * (conj x)) :=
by rw [mul_conj, of_real_re, abs_of_real, norm_sq_eq_abs, sq, _root_.abs_mul, abs_abs]
lemma abs_sq_re_add_conj (x : K) : (abs (x + x†))^2 = (re (x + x†))^2 :=
by simp [sq, ←norm_sq_eq_abs, norm_sq]
lemma abs_sq_re_add_conj' (x : K) : (abs (x† + x))^2 = (re (x† + x))^2 :=
by simp [sq, ←norm_sq_eq_abs, norm_sq]
lemma conj_mul_eq_norm_sq_left (x : K) : x† * x = ((norm_sq x) : K) :=
begin
rw ext_iff,
refine ⟨by simp [of_real_re, mul_re, conj_re, conj_im, norm_sq],_⟩,
simp [of_real_im, mul_im, conj_im, conj_re, mul_comm],
end
/-! ### Cauchy sequences -/
theorem is_cau_seq_re (f : cau_seq K abs) : is_cau_seq abs' (λ n, re (f n)) :=
λ ε ε0, (f.cauchy ε0).imp $ λ i H j ij,
lt_of_le_of_lt (by simpa using abs_re_le_abs (f j - f i)) (H _ ij)
theorem is_cau_seq_im (f : cau_seq K abs) : is_cau_seq abs' (λ n, im (f n)) :=
λ ε ε0, (f.cauchy ε0).imp $ λ i H j ij,
lt_of_le_of_lt (by simpa using abs_im_le_abs (f j - f i)) (H _ ij)
/-- The real part of a K Cauchy sequence, as a real Cauchy sequence. -/
noncomputable def cau_seq_re (f : cau_seq K abs) : cau_seq ℝ abs' :=
⟨_, is_cau_seq_re f⟩
/-- The imaginary part of a K Cauchy sequence, as a real Cauchy sequence. -/
noncomputable def cau_seq_im (f : cau_seq K abs) : cau_seq ℝ abs' :=
⟨_, is_cau_seq_im f⟩
lemma is_cau_seq_abs {f : ℕ → K} (hf : is_cau_seq abs f) :
is_cau_seq abs' (abs ∘ f) :=
λ ε ε0, let ⟨i, hi⟩ := hf ε ε0 in
⟨i, λ j hj, lt_of_le_of_lt (abs_abs_sub_le_abs_sub _ _) (hi j hj)⟩
@[simp, norm_cast, priority 900] lemma of_real_prod {α : Type*} (s : finset α) (f : α → ℝ) :
((∏ i in s, f i : ℝ) : K) = ∏ i in s, (f i : K) :=
ring_hom.map_prod _ _ _
@[simp, norm_cast, priority 900] lemma of_real_sum {α : Type*} (s : finset α) (f : α → ℝ) :
((∑ i in s, f i : ℝ) : K) = ∑ i in s, (f i : K) :=
ring_hom.map_sum _ _ _
@[simp, norm_cast] lemma of_real_finsupp_sum
{α M : Type*} [has_zero M] (f : α →₀ M) (g : α → M → ℝ) :
((f.sum (λ a b, g a b) : ℝ) : K) = f.sum (λ a b, ((g a b) : K)) :=
ring_hom.map_finsupp_sum _ f g
@[simp, norm_cast] lemma of_real_finsupp_prod
{α M : Type*} [has_zero M] (f : α →₀ M) (g : α → M → ℝ) :
((f.prod (λ a b, g a b) : ℝ) : K) = f.prod (λ a b, ((g a b) : K)) :=
ring_hom.map_finsupp_prod _ f g
end is_R_or_C
namespace finite_dimensional
variables {K : Type*} [is_R_or_C K]
open_locale classical
open is_R_or_C
/-- This instance generates a type-class problem with a metavariable `?m` that should satisfy
`is_R_or_C ?m`. Since this can only be satisfied by `ℝ` or `ℂ`, this does not cause problems. -/
library_note "is_R_or_C instance"
/-- An `is_R_or_C` field is finite-dimensional over `ℝ`, since it is spanned by `{1, I}`. -/
@[nolint dangerous_instance] instance is_R_or_C_to_real : finite_dimensional ℝ K :=
is_noetherian.iff_fg.mpr ⟨⟨{1, I},
begin
rw eq_top_iff,
intros a _,
rw [finset.coe_insert, finset.coe_singleton, submodule.mem_span_insert],
refine ⟨re a, (im a) • I, _, _⟩,
{ rw submodule.mem_span_singleton,
use im a },
simp [re_add_im a, algebra.smul_def, algebra_map_eq_of_real]
end⟩⟩
/-- Over an `is_R_or_C` field, we can register the properness of finite-dimensional normed spaces as
an instance. -/
@[priority 900, nolint dangerous_instance] instance proper_is_R_or_C -- note [is_R_or_C instance]
{E : Type*} [normed_group E] [normed_space K E] [finite_dimensional K E] :
proper_space E :=
begin
letI : normed_space ℝ E := restrict_scalars.normed_space ℝ K E,
letI : is_scalar_tower ℝ K E := restrict_scalars.is_scalar_tower _ _ _,
letI : finite_dimensional ℝ E := finite_dimensional.trans ℝ K E,
apply_instance
end
end finite_dimensional
section instances
noncomputable instance real.is_R_or_C : is_R_or_C ℝ :=
{ re := add_monoid_hom.id ℝ,
im := 0,
conj := ring_hom.id ℝ,
I := 0,
I_re_ax := by simp only [add_monoid_hom.map_zero],
I_mul_I_ax := or.intro_left _ rfl,
re_add_im_ax := λ z, by unfold_coes; simp [add_zero, id.def, mul_zero],
of_real_re_ax := λ r, by simp only [add_monoid_hom.id_apply, algebra.id.map_eq_self],
of_real_im_ax := λ r, by simp only [add_monoid_hom.zero_apply],
mul_re_ax := λ z w,
by simp only [sub_zero, mul_zero, add_monoid_hom.zero_apply, add_monoid_hom.id_apply],
mul_im_ax := λ z w, by simp only [add_zero, zero_mul, mul_zero, add_monoid_hom.zero_apply],
conj_re_ax := λ z, by simp only [ring_hom.id_apply],
conj_im_ax := λ z, by simp only [neg_zero, add_monoid_hom.zero_apply],
conj_I_ax := by simp only [ring_hom.map_zero, neg_zero],
norm_sq_eq_def_ax := λ z, by simp only [sq, norm, ←abs_mul, abs_mul_self z, add_zero,
mul_zero, add_monoid_hom.zero_apply, add_monoid_hom.id_apply],
mul_im_I_ax := λ z, by simp only [mul_zero, add_monoid_hom.zero_apply],
inv_def_ax := λ z, by simp [sq, real.norm_eq_abs, abs_mul_abs_self, ← div_eq_mul_inv],
div_I_ax := λ z, by simp only [div_zero, mul_zero, neg_zero]}
end instances
namespace is_R_or_C
section cleanup_lemmas
local notation `reR` := @is_R_or_C.re ℝ _
local notation `imR` := @is_R_or_C.im ℝ _
local notation `conjR` := @is_R_or_C.conj ℝ _
local notation `IR` := @is_R_or_C.I ℝ _
local notation `absR` := @is_R_or_C.abs ℝ _
local notation `norm_sqR` := @is_R_or_C.norm_sq ℝ _
@[simp] lemma re_to_real {x : ℝ} : reR x = x := rfl
@[simp] lemma im_to_real {x : ℝ} : imR x = 0 := rfl
@[simp] lemma conj_to_real {x : ℝ} : conjR x = x := rfl
@[simp] lemma I_to_real : IR = 0 := rfl
@[simp] lemma norm_sq_to_real {x : ℝ} : norm_sq x = x*x := by simp [is_R_or_C.norm_sq]
@[simp] lemma abs_to_real {x : ℝ} : absR x = _root_.abs x :=
by simp [is_R_or_C.abs, abs, real.sqrt_mul_self_eq_abs]
@[simp] lemma coe_real_eq_id : @coe ℝ ℝ _ = id := rfl
end cleanup_lemmas
section linear_maps
variables {K : Type*} [is_R_or_C K]
/-- The real part in a `is_R_or_C` field, as a linear map. -/
noncomputable def re_lm : K →ₗ[ℝ] ℝ :=
{ map_smul' := smul_re, .. re }
@[simp] lemma re_lm_coe : (re_lm : K → ℝ) = re := rfl
/-- The real part in a `is_R_or_C` field, as a continuous linear map. -/
noncomputable def re_clm : K →L[ℝ] ℝ :=
linear_map.mk_continuous re_lm 1 $ by
{ simp only [norm_eq_abs, re_lm_coe, one_mul, abs_to_real], exact abs_re_le_abs, }
@[simp] lemma re_clm_norm : ∥(re_clm : K →L[ℝ] ℝ)∥ = 1 :=
begin
apply le_antisymm (linear_map.mk_continuous_norm_le _ zero_le_one _),
convert continuous_linear_map.ratio_le_op_norm _ (1 : K),
simp,
end
@[simp, norm_cast] lemma re_clm_coe : ((re_clm : K →L[ℝ] ℝ) : K →ₗ[ℝ] ℝ) = re_lm := rfl
@[simp] lemma re_clm_apply : ((re_clm : K →L[ℝ] ℝ) : K → ℝ) = re := rfl
@[continuity] lemma continuous_re : continuous (re : K → ℝ) := re_clm.continuous
/-- The imaginary part in a `is_R_or_C` field, as a linear map. -/
noncomputable def im_lm : K →ₗ[ℝ] ℝ :=
{ map_smul' := smul_im, .. im }
@[simp] lemma im_lm_coe : (im_lm : K → ℝ) = im := rfl
/-- The imaginary part in a `is_R_or_C` field, as a continuous linear map. -/
noncomputable def im_clm : K →L[ℝ] ℝ :=
linear_map.mk_continuous im_lm 1 $ by
{ simp only [norm_eq_abs, re_lm_coe, one_mul, abs_to_real], exact abs_im_le_abs, }
@[simp, norm_cast] lemma im_clm_coe : ((im_clm : K →L[ℝ] ℝ) : K →ₗ[ℝ] ℝ) = im_lm := rfl
@[simp] lemma im_clm_apply : ((im_clm : K →L[ℝ] ℝ) : K → ℝ) = im := rfl
@[continuity] lemma continuous_im : continuous (im : K → ℝ) := im_clm.continuous
/-- Conjugate as an `ℝ`-algebra equivalence -/
noncomputable def conj_ae : K ≃ₐ[ℝ] K :=
{ inv_fun := conj,
left_inv := conj_conj,
right_inv := conj_conj,
commutes' := conj_of_real,
.. conj }
@[simp] lemma conj_ae_coe : (conj_ae : K → K) = conj := rfl
/-- Conjugate as a linear isometry -/
noncomputable def conj_lie : K ≃ₗᵢ[ℝ] K := ⟨conj_ae.to_linear_equiv, λ z, by simp [norm_eq_abs]⟩
@[simp] lemma conj_lie_apply : (conj_lie : K → K) = conj := rfl
/-- Conjugate as a continuous linear equivalence -/
noncomputable def conj_cle : K ≃L[ℝ] K := @conj_lie K _
@[simp] lemma conj_cle_coe : (@conj_cle K _).to_linear_equiv = conj_ae.to_linear_equiv := rfl
@[simp] lemma conj_cle_apply : (conj_cle : K → K) = conj := rfl
@[simp] lemma conj_cle_norm : ∥(@conj_cle K _ : K →L[ℝ] K)∥ = 1 :=
(@conj_lie K _).to_linear_isometry.norm_to_continuous_linear_map
@[continuity] lemma continuous_conj : continuous (conj : K → K) := conj_lie.continuous
/-- The `ℝ → K` coercion, as a linear map -/
noncomputable def of_real_am : ℝ →ₐ[ℝ] K := algebra.of_id ℝ K
@[simp] lemma of_real_am_coe : (of_real_am : ℝ → K) = coe := rfl
/-- The ℝ → K coercion, as a linear isometry -/
noncomputable def of_real_li : ℝ →ₗᵢ[ℝ] K :=
{ to_linear_map := of_real_am.to_linear_map, norm_map' := by simp [norm_eq_abs] }
@[simp] lemma of_real_li_apply : (of_real_li : ℝ → K) = coe := rfl
/-- The `ℝ → K` coercion, as a continuous linear map -/
noncomputable def of_real_clm : ℝ →L[ℝ] K := of_real_li.to_continuous_linear_map
@[simp] lemma of_real_clm_coe : ((@of_real_clm K _) : ℝ →ₗ[ℝ] K) = of_real_am.to_linear_map := rfl
@[simp] lemma of_real_clm_apply : (of_real_clm : ℝ → K) = coe := rfl
@[simp] lemma of_real_clm_norm : ∥(of_real_clm : ℝ →L[ℝ] K)∥ = 1 :=
linear_isometry.norm_to_continuous_linear_map of_real_li
@[continuity] lemma continuous_of_real : continuous (coe : ℝ → K) := of_real_li.continuous
end linear_maps
end is_R_or_C
section normalization
variables {K : Type*} [is_R_or_C K]
variables {E : Type*} [normed_group E] [normed_space K E]
open is_R_or_C
/- Note: one might think the following lemma belongs in `analysis.normed_space.basic`. But it
can't be placed there, because that file is an import of `data.complex.is_R_or_C`! -/
/-- Lemma to normalize a vector in a normed space `E` over either `ℂ` or `ℝ` to unit length. -/
@[simp] lemma norm_smul_inv_norm {x : E} (hx : x ≠ 0) : ∥(∥x∥⁻¹ : K) • x∥ = 1 :=
begin
have h : ∥(∥x∥ : K)∥ = ∥x∥,
{ rw norm_eq_abs,
exact abs_of_nonneg (norm_nonneg _) },
have : ∥x∥ ≠ 0 := by simp [hx],
field_simp [norm_smul, h]
end
end normalization
|
e48f8ad37c71fc8c41af8132b5f10e4b3a640e90 | 618003631150032a5676f229d13a079ac875ff77 | /src/category_theory/limits/shapes/constructions/equalizers.lean | 29f3edd058692ecdc7e7d8ec52a7e44b076055da | [
"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 | 2,713 | lean | /-
Copyright (c) 2020 Bhavik Mehta. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Bhavik Mehta
-/
import category_theory.limits.shapes.equalizers
import category_theory.limits.shapes.binary_products
import category_theory.limits.shapes.pullbacks
/-!
# Constructing equalizers from pullbacks and binary products.
If a category has pullbacks and binary products, then it has equalizers.
TODO: provide the dual result.
-/
universes v u
open category_theory category_theory.category
namespace category_theory.limits
variables {C : Type u} [category.{v} C] [has_binary_products.{v} C] [has_pullbacks.{v} C]
-- We hide the "implementation details" inside a namespace
namespace has_equalizers_of_pullbacks_and_binary_products
/-- Define the equalizing object -/
@[reducible]
def construct_equalizer (F : walking_parallel_pair ⥤ C) : C :=
pullback (prod.lift (𝟙 _) (F.map walking_parallel_pair_hom.left))
(prod.lift (𝟙 _) (F.map walking_parallel_pair_hom.right))
/-- Define the equalizing morphism -/
abbreviation pullback_fst (F : walking_parallel_pair ⥤ C) :
construct_equalizer F ⟶ F.obj walking_parallel_pair.zero :=
pullback.fst
lemma pullback_fst_eq_pullback_snd (F : walking_parallel_pair ⥤ C) :
pullback_fst F = pullback.snd :=
by convert pullback.condition =≫ limits.prod.fst; simp
/-- Define the equalizing cone -/
@[reducible]
def equalizer_cone (F : walking_parallel_pair ⥤ C) : cone F :=
cone.of_fork
(fork.of_ι (pullback_fst F)
(begin
conv_rhs { rw pullback_fst_eq_pullback_snd, },
convert pullback.condition =≫ limits.prod.snd using 1; simp
end))
/-- Show the equalizing cone is a limit -/
def equalizer_cone_is_limit (F : walking_parallel_pair ⥤ C) : is_limit (equalizer_cone F) :=
{ lift :=
begin
intro c, apply pullback.lift (c.π.app _) (c.π.app _),
apply limit.hom_ext,
rintro (_ | _); simp
end,
fac' := by rintros c (_ | _); simp,
uniq' :=
begin
intros c _ J,
have J0 := J walking_parallel_pair.zero, simp at J0,
apply pullback.hom_ext,
{ rwa limit.lift_π },
{ erw [limit.lift_π, ← J0, pullback_fst_eq_pullback_snd] }
end }
end has_equalizers_of_pullbacks_and_binary_products
open has_equalizers_of_pullbacks_and_binary_products
/-- Any category with pullbacks and binary products, has equalizers. -/
-- This is not an instance, as it is not always how one wants to construct equalizers!
def has_equalizers_of_pullbacks_and_binary_products :
has_equalizers.{v} C :=
{ has_limits_of_shape :=
{ has_limit := λ F,
{ cone := equalizer_cone F,
is_limit := equalizer_cone_is_limit F } } }
end category_theory.limits
|
da692c9243c80d54d4a4233444139f1038b976a1 | 432d948a4d3d242fdfb44b81c9e1b1baacd58617 | /src/group_theory/group_action/group.lean | 2d5d6cb9b2723b2f6d02ff11e63264dbbf71b7ee | [
"Apache-2.0"
] | permissive | JLimperg/aesop3 | 306cc6570c556568897ed2e508c8869667252e8a | a4a116f650cc7403428e72bd2e2c4cda300fe03f | refs/heads/master | 1,682,884,916,368 | 1,620,320,033,000 | 1,620,320,033,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 6,072 | 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.defs
import algebra.group.units
import algebra.group_with_zero
import data.equiv.mul_add
import data.equiv.mul_add_aut
import group_theory.perm.basic
/-!
# Group actions applied to various types of group
This file contains lemmas about `smul` on `units`, `group_with_zero`, and `group`.
-/
universes u v w
variables {α : Type u} {β : Type v} {γ : Type w}
section mul_action
section units
variables [monoid α] [mul_action α β]
@[simp, to_additive] lemma units.inv_smul_smul (u : units α) (x : β) :
(↑u⁻¹:α) • (u:α) • x = x :=
by rw [smul_smul, u.inv_mul, one_smul]
@[simp, to_additive] lemma units.smul_inv_smul (u : units α) (x : β) :
(u:α) • (↑u⁻¹:α) • x = x :=
by rw [smul_smul, u.mul_inv, one_smul]
/-- If a monoid `α` acts on `β`, then each `u : units α` defines a permutation of `β`. -/
@[to_additive] def units.smul_perm (u : units α) : equiv.perm β :=
⟨λ x, (u:α) • x, λ x, (↑u⁻¹:α) • x, u.inv_smul_smul, u.smul_inv_smul⟩
/-- If an additive monoid `α` acts on `β`, then each `u : add_units α` defines a permutation
of `β`. -/
add_decl_doc add_units.vadd_perm
/-- If a monoid `α` acts on `β`, then each `u : units α` defines a permutation of `β`. -/
def units.smul_perm_hom : units α →* equiv.perm β :=
{ to_fun := units.smul_perm,
map_one' := equiv.ext $ one_smul α,
map_mul' := λ u₁ u₂, equiv.ext $ mul_smul (u₁:α) u₂ }
/-- If an additive monoid `α` acts on `β`, then each `u : add_units α` defines a permutation
of `β`. -/
def add_units.vadd_perm_hom {M : Type*} [add_monoid M] [add_action M β] :
add_units M →+ additive (equiv.perm β) :=
{ to_fun := λ u, additive.of_mul u.vadd_perm,
map_zero' := equiv.ext $ zero_vadd M,
map_add' := λ u₁ u₂, equiv.ext $ add_vadd (u₁:M) u₂ }
@[simp, to_additive] lemma units.smul_left_cancel (u : units α) {x y : β} :
(u:α) • x = (u:α) • y ↔ x = y :=
u.smul_perm.apply_eq_iff_eq
@[to_additive] lemma units.smul_eq_iff_eq_inv_smul (u : units α) {x y : β} :
(u:α) • x = y ↔ x = (↑u⁻¹:α) • y :=
u.smul_perm.apply_eq_iff_eq_symm_apply
@[to_additive] lemma is_unit.smul_left_cancel {a : α} (ha : is_unit a) {x y : β} :
a • x = a • y ↔ x = y :=
let ⟨u, hu⟩ := ha in hu ▸ u.smul_left_cancel
end units
section gwz
variables [group_with_zero α] [mul_action α β]
@[simp]
lemma inv_smul_smul' {c : α} (hc : c ≠ 0) (x : β) : c⁻¹ • c • x = x :=
(units.mk0 c hc).inv_smul_smul x
@[simp]
lemma smul_inv_smul' {c : α} (hc : c ≠ 0) (x : β) : c • c⁻¹ • x = x :=
(units.mk0 c hc).smul_inv_smul x
lemma inv_smul_eq_iff' {a : α} (ha : a ≠ 0) {x y : β} : a⁻¹ • x = y ↔ x = a • y :=
(units.mk0 a ha).smul_perm.symm_apply_eq
lemma eq_inv_smul_iff' {a : α} (ha : a ≠ 0) {x y : β} : x = a⁻¹ • y ↔ a • x = y :=
(units.mk0 a ha).smul_perm.eq_symm_apply
end gwz
section group
variables [group α] [mul_action α β]
@[simp, to_additive] lemma inv_smul_smul (c : α) (x : β) : c⁻¹ • c • x = x :=
(to_units c).inv_smul_smul x
@[simp, to_additive] lemma smul_inv_smul (c : α) (x : β) : c • c⁻¹ • x = x :=
(to_units c).smul_inv_smul x
@[to_additive] lemma inv_smul_eq_iff {a : α} {x y : β} : a⁻¹ • x = y ↔ x = a • y :=
(to_units a).smul_perm.symm_apply_eq
@[to_additive] lemma eq_inv_smul_iff {a : α} {x y : β} : x = a⁻¹ • y ↔ a • x = y :=
(to_units a).smul_perm.eq_symm_apply
variables (α) (β)
/-- Given an action of a group `α` on a set `β`, each `g : α` defines a permutation of `β`. -/
def mul_action.to_perm : α →* equiv.perm β :=
units.smul_perm_hom.comp to_units.to_monoid_hom
variables {α} {β}
@[to_additive] protected lemma mul_action.bijective (g : α) : function.bijective (λ b : β, g • b) :=
(to_units g).smul_perm.bijective
@[to_additive] protected lemma mul_action.injective (g : α) : function.injective (λ b : β, g • b) :=
(mul_action.bijective g).injective
@[to_additive] lemma smul_left_cancel (g : α) {x y : β} (h : g • x = g • y) : x = y :=
mul_action.injective g h
@[simp, to_additive] lemma smul_left_cancel_iff (g : α) {x y : β} : g • x = g • y ↔ x = y :=
(mul_action.injective g).eq_iff
end group
end mul_action
section distrib_mul_action
variables [monoid α] [add_monoid β] [distrib_mul_action α β]
theorem units.smul_eq_zero (u : units α) {x : β} : (u : α) • x = 0 ↔ x = 0 :=
⟨λ h, by rw [← u.inv_smul_smul x, h, smul_zero], λ h, h.symm ▸ smul_zero _⟩
theorem units.smul_ne_zero (u : units α) {x : β} : (u : α) • x ≠ 0 ↔ x ≠ 0 :=
not_congr u.smul_eq_zero
@[simp] theorem is_unit.smul_eq_zero {u : α} (hu : is_unit u) {x : β} :
u • x = 0 ↔ x = 0 :=
exists.elim hu $ λ u hu, hu ▸ u.smul_eq_zero
end distrib_mul_action
section arrow
/-- If `G` acts on `A`, then it acts also on `A → B`, by `(g • F) a = F (g⁻¹ • a)`. -/
@[simps] def arrow_action {G A B : Type*} [group G] [mul_action G A] : mul_action G (A → B) :=
{ smul := λ g F a, F (g⁻¹ • a),
one_smul := by { intro, simp only [one_inv, one_smul] },
mul_smul := by { intros, simp only [mul_smul, mul_inv_rev] } }
local attribute [instance] arrow_action
/-- Given groups `G H` with `G` acting on `A`, `G` acts by
multiplicative automorphisms on `A → H`. -/
@[simps] def mul_aut_arrow {G A H} [group G] [mul_action G A] [group H] : G →* mul_aut (A → H) :=
{ to_fun := λ g,
{ to_fun := λ F, g • F,
inv_fun := λ F, g⁻¹ • F,
left_inv := λ F, inv_smul_smul g F,
right_inv := λ F, smul_inv_smul g F,
map_mul' := by { intros, ext, simp only [arrow_action_to_has_scalar_smul, pi.mul_apply] } },
map_one' := by { ext, simp only [mul_aut.one_apply, mul_equiv.coe_mk, one_smul] },
map_mul' := by { intros, ext, simp only [mul_smul, mul_equiv.coe_mk, mul_aut.mul_apply] } }
end arrow
|
c07e45bdc95d948090393bb218cb73f6a62b3c73 | 9b9a16fa2cb737daee6b2785474678b6fa91d6d4 | /src/data/set/countable.lean | 13fafc8de8ba0e182b8525b2b1583861347c0926 | [
"Apache-2.0"
] | permissive | johoelzl/mathlib | 253f46daa30b644d011e8e119025b01ad69735c4 | 592e3c7a2dfbd5826919b4605559d35d4d75938f | refs/heads/master | 1,625,657,216,488 | 1,551,374,946,000 | 1,551,374,946,000 | 98,915,829 | 0 | 0 | Apache-2.0 | 1,522,917,267,000 | 1,501,524,499,000 | Lean | UTF-8 | Lean | false | false | 5,621 | lean | /-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Johannes Hölzl
Countable sets.
-/
import data.equiv.list data.set.finite logic.function data.set.function
noncomputable theory
open function set encodable
open classical (hiding some)
local attribute [instance] prop_decidable
universes u v w
variables {α : Type u} {β : Type v} {γ : Type w}
namespace set
/-- Countable sets
A set is countable if there exists an encoding of the set into the natural numbers.
An encoding is an injection with a partial inverse, which can be viewed as a
constructive analogue of countability. (For the most part, theorems about
`countable` will be classical and `encodable` will be constructive.)
-/
def countable (s : set α) : Prop := nonempty (encodable s)
lemma countable_iff_exists_injective {s : set α} :
countable s ↔ ∃f:s → ℕ, injective f :=
⟨λ ⟨h⟩, by exactI ⟨encode, encode_injective⟩,
λ ⟨f, h⟩, ⟨⟨f, partial_inv f, partial_inv_left h⟩⟩⟩
lemma countable_iff_exists_inj_on {s : set α} :
countable s ↔ ∃ f : α → ℕ, inj_on f s :=
countable_iff_exists_injective.trans
⟨λ ⟨f, hf⟩, ⟨λ a, if h : a ∈ s then f ⟨a, h⟩ else 0,
λ a b as bs h, congr_arg subtype.val $
hf $ by simpa [as, bs] using h⟩,
λ ⟨f, hf⟩, ⟨_, inj_on_iff_injective.1 hf⟩⟩
lemma countable_iff_exists_surjective [ne : inhabited α] {s : set α} :
countable s ↔ ∃f:ℕ → α, s ⊆ range f :=
⟨λ ⟨h⟩, by exactI ⟨λ n, ((decode s n).map subtype.val).iget,
λ a as, ⟨encode (⟨a, as⟩ : s), by simp [encodek]⟩⟩,
λ ⟨f, hf⟩, ⟨⟨
λ x, inv_fun f x.1,
λ n, if h : f n ∈ s then some ⟨f n, h⟩ else none,
λ ⟨x, hx⟩, begin
have := inv_fun_eq (hf hx), dsimp at this ⊢,
simp [this, hx]
end⟩⟩⟩
def countable.to_encodable {s : set α} : countable s → encodable s :=
classical.choice
lemma countable_encodable' (s : set α) [H : encodable s] : countable s :=
⟨H⟩
lemma countable_encodable [encodable α] (s : set α) : countable s :=
⟨by apply_instance⟩
@[simp] lemma countable_empty : countable (∅ : set α) :=
⟨⟨λ x, x.2.elim, λ n, none, λ x, x.2.elim⟩⟩
@[simp] lemma countable_singleton (a : α) : countable ({a} : set α) :=
⟨of_equiv _ (equiv.set.singleton a)⟩
lemma countable_subset {s₁ s₂ : set α} (h : s₁ ⊆ s₂) : countable s₂ → countable s₁
| ⟨H⟩ := ⟨@of_inj _ _ H _ (embedding_of_subset h).2⟩
lemma countable_image {s : set α} (f : α → β) (hs : countable s) : countable (f '' s) :=
let f' : s → f '' s := λ⟨a, ha⟩, ⟨f a, mem_image_of_mem f ha⟩ in
have hf' : surjective f', from assume ⟨b, a, ha, hab⟩, ⟨⟨a, ha⟩, subtype.eq hab⟩,
⟨@encodable.of_inj _ _ hs.to_encodable (surj_inv hf') (injective_surj_inv hf')⟩
lemma countable_range [encodable α] (f : α → β) : countable (range f) :=
by rw ← image_univ; exact countable_image _ (countable_encodable _)
lemma countable_of_injective_of_countable_image {s : set α} {f : α → β}
(hf : inj_on f s) (hs : countable (f '' s)) : countable s :=
let ⟨g, hg⟩ := countable_iff_exists_inj_on.1 hs in
countable_iff_exists_inj_on.2 ⟨g ∘ f, inj_on_comp (maps_to_image _ _) hg hf⟩
lemma countable_Union {t : α → set β} [encodable α] (ht : ∀a, countable (t a)) :
countable (⋃a, t a) :=
by haveI := (λ a, (ht a).to_encodable);
rw Union_eq_range_sigma; apply countable_range
lemma countable_bUnion {s : set α} {t : α → set β} (hs : countable s) (ht : ∀a∈s, countable (t a)) :
countable (⋃a∈s, t a) :=
begin
rw bUnion_eq_Union,
haveI := hs.to_encodable,
exact countable_Union (by simpa using ht)
end
lemma countable_sUnion {s : set (set α)} (hs : countable s) (h : ∀a∈s, countable a) :
countable (⋃₀ s) :=
by rw sUnion_eq_bUnion; exact countable_bUnion hs h
lemma countable_Union_Prop {p : Prop} {t : p → set β} (ht : ∀h:p, countable (t h)) :
countable (⋃h:p, t h) :=
by by_cases p; simp [h, ht]
lemma countable_union {s₁ s₂ : set α} (h₁ : countable s₁) (h₂ : countable s₂) : countable (s₁ ∪ s₂) :=
by rw union_eq_Union; exact
countable_Union (bool.forall_bool.2 ⟨h₂, h₁⟩)
lemma countable_insert {s : set α} {a : α} (h : countable s) : countable (insert a s) :=
by rw [set.insert_eq]; from countable_union (countable_singleton _) h
lemma countable_finite {s : set α} : finite s → countable s
| ⟨h⟩ := nonempty_of_trunc (by exactI trunc_encodable_of_fintype s)
lemma countable_set_of_finite_subset {s : set α} : countable s →
countable {t | finite t ∧ t ⊆ s} | ⟨h⟩ :=
begin
resetI,
refine countable_subset _ (countable_range
(λ t : finset s, {a | ∃ h:a ∈ s, subtype.mk a h ∈ t})),
rintro t ⟨⟨ht⟩, ts⟩,
refine ⟨finset.univ.map (embedding_of_subset ts),
set.ext $ λ a, _⟩,
simp, split,
{ rintro ⟨as, b, bt, e⟩,
cases congr_arg subtype.val e, exact bt },
{ exact λ h, ⟨ts h, _, h, rfl⟩ }
end
lemma countable_pi {π : α → Type*} [fintype α] {s : Πa, set (π a)} (hs : ∀a, countable (s a)) :
countable {f : Πa, π a | ∀a, f a ∈ s a} :=
countable_subset
(show {f : Πa, π a | ∀a, f a ∈ s a} ⊆ range (λf : Πa, s a, λa, (f a).1), from
assume f hf, ⟨λa, ⟨f a, hf a⟩, funext $ assume a, rfl⟩) $
have trunc (encodable (Π (a : α), s a)), from
@encodable.fintype_pi α _ _ _ (assume a, (hs a).to_encodable),
trunc.induction_on this $ assume h,
@countable_range _ _ h _
end set
|
f0b322980def44486dcbadf0802857c82ad9fa04 | f7315930643edc12e76c229a742d5446dad77097 | /hott/algebra/precategory/functor.hlean | 9022101508af3075edb826150a10e965b36aaeac | [
"Apache-2.0"
] | permissive | bmalehorn/lean | 8f77b762a76c59afff7b7403f9eb5fc2c3ce70c1 | 53653c352643751c4b62ff63ec5e555f11dae8eb | refs/heads/master | 1,610,945,684,489 | 1,429,681,220,000 | 1,429,681,449,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 10,582 | 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),
-- TODO(Leo): investigate why we need to use relaxed-exact (rexact) tactic here
exact (pr₁ S.2.2), rexact (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
|
d44e3d906f531caf39bb80761798473a782798bd | 618003631150032a5676f229d13a079ac875ff77 | /src/data/pnat/basic.lean | 292d5fb92fb1447d60dc640500a12b18da0c1329 | [
"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 | 13,492 | lean | /-
Copyright (c) 2017 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Mario Carneiro, Neil Strickland
-/
import data.nat.prime
/-- `ℕ+` is the type of positive natural numbers. It is defined as a subtype,
and the VM representation of `ℕ+` is the same as `ℕ` because the proof
is not stored. -/
def pnat := {n : ℕ // 0 < n}
notation `ℕ+` := pnat
instance coe_pnat_nat : has_coe ℕ+ ℕ := ⟨subtype.val⟩
instance : has_repr ℕ+ := ⟨λ n, repr n.1⟩
namespace nat
/-- Convert a natural number to a positive natural number. The
positivity assumption is inferred by `dec_trivial`. -/
def to_pnat (n : ℕ) (h : 0 < n . tactic.exact_dec_trivial) : ℕ+ := ⟨n, h⟩
/-- Write a successor as an element of `ℕ+`. -/
def succ_pnat (n : ℕ) : ℕ+ := ⟨succ n, succ_pos n⟩
@[simp] theorem succ_pnat_coe (n : ℕ) : (succ_pnat n : ℕ) = succ n := rfl
theorem succ_pnat_inj {n m : ℕ} : succ_pnat n = succ_pnat m → n = m :=
λ h, by { let h' := congr_arg (coe : ℕ+ → ℕ) h, exact nat.succ_inj h' }
/-- Convert a natural number to a pnat. `n+1` is mapped to itself,
and `0` becomes `1`. -/
def to_pnat' (n : ℕ) : ℕ+ := succ_pnat (pred n)
@[simp] theorem to_pnat'_coe : ∀ (n : ℕ),
((to_pnat' n) : ℕ) = ite (0 < n) n 1
| 0 := rfl
| (m + 1) := by {rw [if_pos (succ_pos m)], refl}
namespace primes
instance coe_pnat : has_coe nat.primes ℕ+ := ⟨λ p, ⟨(p : ℕ), p.property.pos⟩⟩
theorem coe_pnat_nat (p : nat.primes) : ((p : ℕ+) : ℕ) = p := rfl
theorem coe_pnat_inj (p q : nat.primes) : (p : ℕ+) = (q : ℕ+) → p = q := λ h,
begin
replace h : ((p : ℕ+) : ℕ) = ((q : ℕ+) : ℕ) := congr_arg subtype.val h,
rw [coe_pnat_nat, coe_pnat_nat] at h,
exact subtype.eq h,
end
end primes
end nat
namespace pnat
open nat
/-- We now define a long list of structures on ℕ+ induced by
similar structures on ℕ. Most of these behave in a completely
obvious way, but there are a few things to be said about
subtraction, division and powers.
-/
instance : decidable_eq ℕ+ := λ (a b : ℕ+), by apply_instance
instance : decidable_linear_order ℕ+ :=
subtype.decidable_linear_order _
@[simp] lemma mk_le_mk (n k : ℕ) (hn : 0 < n) (hk : 0 < k) :
(⟨n, hn⟩ : ℕ+) ≤ ⟨k, hk⟩ ↔ n ≤ k := iff.rfl
@[simp] lemma mk_lt_mk (n k : ℕ) (hn : 0 < n) (hk : 0 < k) :
(⟨n, hn⟩ : ℕ+) < ⟨k, hk⟩ ↔ n < k := iff.rfl
@[simp, norm_cast] lemma coe_le_coe (n k : ℕ+) : (n:ℕ) ≤ k ↔ n ≤ k := iff.rfl
@[simp, norm_cast] lemma coe_lt_coe (n k : ℕ+) : (n:ℕ) < k ↔ n < k := iff.rfl
@[simp] theorem pos (n : ℕ+) : 0 < (n : ℕ) := n.2
theorem eq {m n : ℕ+} : (m : ℕ) = n → m = n := subtype.eq
@[simp] theorem mk_coe (n h) : ((⟨n, h⟩ : ℕ+) : ℕ) = n := rfl
instance : add_comm_semigroup ℕ+ :=
{ add := λ a b, ⟨(a + b : ℕ), add_pos a.pos b.pos⟩,
add_comm := λ a b, subtype.eq (add_comm a b),
add_assoc := λ a b c, subtype.eq (add_assoc a b c) }
@[simp] theorem add_coe (m n : ℕ+) : ((m + n : ℕ+) : ℕ) = m + n := rfl
instance coe_add_hom : is_add_hom (coe : ℕ+ → ℕ) := ⟨add_coe⟩
instance : add_left_cancel_semigroup ℕ+ :=
{ add_left_cancel := λ a b c h, by {
replace h := congr_arg (coe : ℕ+ → ℕ) h,
rw [add_coe, add_coe] at h,
exact eq ((add_right_inj (a : ℕ)).mp h)},
.. (pnat.add_comm_semigroup) }
instance : add_right_cancel_semigroup ℕ+ :=
{ add_right_cancel := λ a b c h, by {
replace h := congr_arg (coe : ℕ+ → ℕ) h,
rw [add_coe, add_coe] at h,
exact eq ((add_left_inj (b : ℕ)).mp h)},
.. (pnat.add_comm_semigroup) }
@[simp] theorem ne_zero (n : ℕ+) : (n : ℕ) ≠ 0 := ne_of_gt n.2
theorem to_pnat'_coe {n : ℕ} : 0 < n → (n.to_pnat' : ℕ) = n := succ_pred_eq_of_pos
@[simp] theorem coe_to_pnat' (n : ℕ+) : (n : ℕ).to_pnat' = n := eq (to_pnat'_coe n.pos)
instance : comm_monoid ℕ+ :=
{ mul := λ m n, ⟨m.1 * n.1, mul_pos m.2 n.2⟩,
mul_assoc := λ a b c, subtype.eq (mul_assoc _ _ _),
one := succ_pnat 0,
one_mul := λ a, subtype.eq (one_mul _),
mul_one := λ a, subtype.eq (mul_one _),
mul_comm := λ a b, subtype.eq (mul_comm _ _) }
theorem lt_add_one_iff : ∀ {a b : ℕ+}, a < b + 1 ↔ a ≤ b :=
λ a b, nat.lt_add_one_iff
theorem add_one_le_iff : ∀ {a b : ℕ+}, a + 1 ≤ b ↔ a < b :=
λ a b, nat.add_one_le_iff
@[simp] lemma one_le (n : ℕ+) : (1 : ℕ+) ≤ n := n.2
instance : order_bot ℕ+ :=
{ bot := 1,
bot_le := λ a, a.property,
..(by apply_instance : partial_order ℕ+) }
@[simp] lemma bot_eq_zero : (⊥ : ℕ+) = 1 := rfl
instance : inhabited ℕ+ := ⟨1⟩
-- Some lemmas that rewrite `pnat.mk n h`, for `n` an explicit numeral, into explicit numerals.
@[simp] lemma mk_one {h} : (⟨1, h⟩ : ℕ+) = (1 : ℕ+) := rfl
@[simp] lemma mk_bit0 (n) {h} : (⟨bit0 n, h⟩ : ℕ+) = (bit0 ⟨n, pos_of_bit0_pos h⟩ : ℕ+) := rfl
@[simp] lemma mk_bit1 (n) {h} {k} : (⟨bit1 n, h⟩ : ℕ+) = (bit1 ⟨n, k⟩ : ℕ+) := rfl
-- Some lemmas that rewrite inequalities between explicit numerals in `pnat`
-- into the corresponding inequalities in `nat`.
-- TODO: perhaps this should not be attempted by `simp`,
-- and instead we should expect `norm_num` to take care of these directly?
-- TODO: these lemmas are perhaps incomplete:
-- * 1 is not represented as a bit0 or bit1
-- * strict inequalities?
@[simp] lemma bit0_le_bit0 (n m : ℕ+) : (bit0 n) ≤ (bit0 m) ↔ (bit0 (n : ℕ)) ≤ (bit0 (m : ℕ)) := iff.refl _
@[simp] lemma bit0_le_bit1 (n m : ℕ+) : (bit0 n) ≤ (bit1 m) ↔ (bit0 (n : ℕ)) ≤ (bit1 (m : ℕ)) := iff.refl _
@[simp] lemma bit1_le_bit0 (n m : ℕ+) : (bit1 n) ≤ (bit0 m) ↔ (bit1 (n : ℕ)) ≤ (bit0 (m : ℕ)) := iff.refl _
@[simp] lemma bit1_le_bit1 (n m : ℕ+) : (bit1 n) ≤ (bit1 m) ↔ (bit1 (n : ℕ)) ≤ (bit1 (m : ℕ)) := iff.refl _
@[simp] theorem one_coe : ((1 : ℕ+) : ℕ) = 1 := rfl
@[simp] theorem mul_coe (m n : ℕ+) : ((m * n : ℕ+) : ℕ) = m * n := rfl
instance coe_mul_hom : is_monoid_hom (coe : ℕ+ → ℕ) :=
{map_one := one_coe, map_mul := mul_coe}
@[simp] lemma coe_bit0 (a : ℕ+) : ((bit0 a : ℕ+) : ℕ) = bit0 (a : ℕ) := rfl
@[simp] lemma coe_bit1 (a : ℕ+) : ((bit1 a : ℕ+) : ℕ) = bit1 (a : ℕ) := rfl
@[simp] theorem pow_coe (m : ℕ+) (n : ℕ) : ((m ^ n : ℕ+) : ℕ) = (m : ℕ) ^ n :=
by induction n with n ih;
[refl, rw [nat.pow_succ, _root_.pow_succ, mul_coe, mul_comm, ih]]
instance : left_cancel_semigroup ℕ+ :=
{ mul_left_cancel := λ a b c h, by {
replace h := congr_arg (coe : ℕ+ → ℕ) h,
exact eq ((nat.mul_right_inj a.pos).mp h)},
.. (pnat.comm_monoid) }
instance : right_cancel_semigroup ℕ+ :=
{ mul_right_cancel := λ a b c h, by {
replace h := congr_arg (coe : ℕ+ → ℕ) h,
exact eq ((nat.mul_left_inj b.pos).mp h)},
.. (pnat.comm_monoid) }
instance : distrib ℕ+ :=
{ left_distrib := λ a b c, eq (mul_add a b c),
right_distrib := λ a b c, eq (add_mul a b c),
..(pnat.add_comm_semigroup), ..(pnat.comm_monoid) }
/-- Subtraction a - b is defined in the obvious way when
a > b, and by a - b = 1 if a ≤ b.
-/
instance : has_sub ℕ+ := ⟨λ a b, to_pnat' (a - b : ℕ)⟩
theorem sub_coe (a b : ℕ+) : ((a - b : ℕ+) : ℕ) = ite (b < a) (a - b : ℕ) 1 :=
begin
change ((to_pnat' ((a : ℕ) - (b : ℕ)) : ℕ)) =
ite ((a : ℕ) > (b : ℕ)) ((a : ℕ) - (b : ℕ)) 1,
split_ifs with h,
{ exact to_pnat'_coe (nat.sub_pos_of_lt h) },
{ rw [nat.sub_eq_zero_iff_le.mpr (le_of_not_gt h)], refl }
end
theorem add_sub_of_lt {a b : ℕ+} : a < b → a + (b - a) = b :=
λ h, eq $ by { rw [add_coe, sub_coe, if_pos h],
exact nat.add_sub_of_le (le_of_lt h) }
/-- We define m % k and m / k in the same way as for nat
except that when m = n * k we take m % k = k and
m / k = n - 1. This ensures that m % k is always positive
and m = (m % k) + k * (m / k) in all cases. Later we
define a function div_exact which gives the usual m / k
in the case where k divides m.
-/
def mod_div_aux : ℕ+ → ℕ → ℕ → ℕ+ × ℕ
| k 0 q := ⟨k, q.pred⟩
| k (r + 1) q := ⟨⟨r + 1, nat.succ_pos r⟩, q⟩
lemma mod_div_aux_spec : ∀ (k : ℕ+) (r q : ℕ) (h : ¬ (r = 0 ∧ q = 0)),
(((mod_div_aux k r q).1 : ℕ) + k * (mod_div_aux k r q).2 = (r + k * q))
| k 0 0 h := (h ⟨rfl, rfl⟩).elim
| k 0 (q + 1) h := by {
change (k : ℕ) + (k : ℕ) * (q + 1).pred = 0 + (k : ℕ) * (q + 1),
rw [nat.pred_succ, nat.mul_succ, zero_add, add_comm]}
| k (r + 1) q h := rfl
def mod_div (m k : ℕ+) : ℕ+ × ℕ := mod_div_aux k ((m : ℕ) % (k : ℕ)) ((m : ℕ) / (k : ℕ))
def mod (m k : ℕ+) : ℕ+ := (mod_div m k).1
def div (m k : ℕ+) : ℕ := (mod_div m k).2
theorem mod_add_div (m k : ℕ+) : (m : ℕ) = (mod m k) + k * (div m k) :=
begin
let h₀ := nat.mod_add_div (m : ℕ) (k : ℕ),
have : ¬ ((m : ℕ) % (k : ℕ) = 0 ∧ (m : ℕ) / (k : ℕ) = 0),
by { rintro ⟨hr, hq⟩, rw [hr, hq, mul_zero, zero_add] at h₀,
exact (m.ne_zero h₀.symm).elim },
have := mod_div_aux_spec k ((m : ℕ) % (k : ℕ)) ((m : ℕ) / (k : ℕ)) this,
exact (this.trans h₀).symm,
end
theorem mod_coe (m k : ℕ+) :
((mod m k) : ℕ) = ite ((m : ℕ) % (k : ℕ) = 0) (k : ℕ) ((m : ℕ) % (k : ℕ)) :=
begin
dsimp [mod, mod_div],
cases (m : ℕ) % (k : ℕ),
{ rw [if_pos rfl], refl },
{ rw [if_neg n.succ_ne_zero], refl }
end
theorem div_coe (m k : ℕ+) :
((div m k) : ℕ) = ite ((m : ℕ) % (k : ℕ) = 0) ((m : ℕ) / (k : ℕ)).pred ((m : ℕ) / (k : ℕ)) :=
begin
dsimp [div, mod_div],
cases (m : ℕ) % (k : ℕ),
{ rw [if_pos rfl], refl },
{ rw [if_neg n.succ_ne_zero], refl }
end
theorem mod_le (m k : ℕ+) : mod m k ≤ m ∧ mod m k ≤ k :=
begin
change ((mod m k) : ℕ) ≤ (m : ℕ) ∧ ((mod m k) : ℕ) ≤ (k : ℕ),
rw [mod_coe], split_ifs,
{ have hm : (m : ℕ) > 0 := m.pos,
rw [← nat.mod_add_div (m : ℕ) (k : ℕ), h, zero_add] at hm ⊢,
by_cases h' : ((m : ℕ) / (k : ℕ)) = 0,
{ rw [h', mul_zero] at hm, exact (lt_irrefl _ hm).elim},
{ let h' := nat.mul_le_mul_left (k : ℕ)
(nat.succ_le_of_lt (nat.pos_of_ne_zero h')),
rw [mul_one] at h', exact ⟨h', le_refl (k : ℕ)⟩ } },
{ exact ⟨nat.mod_le (m : ℕ) (k : ℕ), le_of_lt (nat.mod_lt (m : ℕ) k.pos)⟩ }
end
instance : has_dvd ℕ+ := ⟨λ k m, (k : ℕ) ∣ (m : ℕ)⟩
theorem dvd_iff {k m : ℕ+} : k ∣ m ↔ (k : ℕ) ∣ (m : ℕ) := by {refl}
theorem dvd_iff' {k m : ℕ+} : k ∣ m ↔ mod m k = k :=
begin
change (k : ℕ) ∣ (m : ℕ) ↔ mod m k = k,
rw [nat.dvd_iff_mod_eq_zero], split,
{ intro h, apply eq, rw [mod_coe, if_pos h] },
{ intro h, by_cases h' : (m : ℕ) % (k : ℕ) = 0,
{ exact h'},
{ replace h : ((mod m k) : ℕ) = (k : ℕ) := congr_arg _ h,
rw [mod_coe, if_neg h'] at h,
exact (ne_of_lt (nat.mod_lt (m : ℕ) k.pos) h).elim } }
end
def div_exact {m k : ℕ+} (h : k ∣ m) : ℕ+ :=
⟨(div m k).succ, nat.succ_pos _⟩
theorem mul_div_exact {m k : ℕ+} (h : k ∣ m) : k * (div_exact h) = m :=
begin
apply eq, rw [mul_coe],
change (k : ℕ) * (div m k).succ = m,
rw [mod_add_div m k, dvd_iff'.mp h, nat.mul_succ, add_comm],
end
theorem dvd_iff'' {k n : ℕ+} : k ∣ n ↔ ∃ m, k * m = n :=
⟨λ h, ⟨div_exact h, mul_div_exact h⟩,
λ ⟨m, h⟩, dvd.intro (m : ℕ)
((mul_coe k m).symm.trans (congr_arg subtype.val h))⟩
theorem dvd_intro {k n : ℕ+} (m : ℕ+) (h : k * m = n) : k ∣ n :=
dvd_iff''.mpr ⟨m, h⟩
theorem dvd_refl (m : ℕ+) : m ∣ m := dvd_intro 1 (mul_one m)
theorem dvd_antisymm {m n : ℕ+} : m ∣ n → n ∣ m → m = n :=
λ hmn hnm, subtype.eq (nat.dvd_antisymm hmn hnm)
protected theorem dvd_trans {k m n : ℕ+} : k ∣ m → m ∣ n → k ∣ n :=
@dvd_trans ℕ _ (k : ℕ) (m : ℕ) (n : ℕ)
theorem one_dvd (n : ℕ+) : 1 ∣ n := dvd_intro n (one_mul n)
theorem dvd_one_iff (n : ℕ+) : n ∣ 1 ↔ n = 1 :=
⟨λ h, dvd_antisymm h (one_dvd n), λ h, h.symm ▸ (dvd_refl 1)⟩
def gcd (n m : ℕ+) : ℕ+ :=
⟨nat.gcd (n : ℕ) (m : ℕ), nat.gcd_pos_of_pos_left (m : ℕ) n.pos⟩
def lcm (n m : ℕ+) : ℕ+ :=
⟨nat.lcm (n : ℕ) (m : ℕ),
by { let h := mul_pos n.pos m.pos,
rw [← gcd_mul_lcm (n : ℕ) (m : ℕ), mul_comm] at h,
exact pos_of_dvd_of_pos (dvd.intro (nat.gcd (n : ℕ) (m : ℕ)) rfl) h }⟩
@[simp] theorem gcd_coe (n m : ℕ+) : ((gcd n m) : ℕ) = nat.gcd n m := rfl
@[simp] theorem lcm_coe (n m : ℕ+) : ((lcm n m) : ℕ) = nat.lcm n m := rfl
theorem gcd_dvd_left (n m : ℕ+) : (gcd n m) ∣ n := nat.gcd_dvd_left (n : ℕ) (m : ℕ)
theorem gcd_dvd_right (n m : ℕ+) : (gcd n m) ∣ m := nat.gcd_dvd_right (n : ℕ) (m : ℕ)
theorem dvd_gcd {m n k : ℕ+} (hm : k ∣ m) (hn : k ∣ n) : k ∣ gcd m n :=
@nat.dvd_gcd (m : ℕ) (n : ℕ) (k : ℕ) hm hn
theorem dvd_lcm_left (n m : ℕ+) : n ∣ lcm n m := nat.dvd_lcm_left (n : ℕ) (m : ℕ)
theorem dvd_lcm_right (n m : ℕ+) : m ∣ lcm n m := nat.dvd_lcm_right (n : ℕ) (m : ℕ)
theorem lcm_dvd {m n k : ℕ+} (hm : m ∣ k) (hn : n ∣ k) : lcm m n ∣ k :=
@nat.lcm_dvd (m : ℕ) (n : ℕ) (k : ℕ) hm hn
theorem gcd_mul_lcm (n m : ℕ+) : (gcd n m) * (lcm n m) = n * m :=
subtype.eq (nat.gcd_mul_lcm (n : ℕ) (m : ℕ))
def prime (p : ℕ+) : Prop := (p : ℕ).prime
end pnat
|
383f156acc673bc867bde2aaeac4a4a5f1ee45d1 | 618003631150032a5676f229d13a079ac875ff77 | /src/category_theory/limits/shapes/constructions/pullbacks.lean | 46b692f33088c596b39464e12b12476705d5ba36 | [
"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 | 3,931 | 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 category_theory.limits.shapes.binary_products
import category_theory.limits.shapes.equalizers
import category_theory.limits.shapes.pullbacks
universes v u
/-!
# Constructing pullbacks from binary products and equalizers
If a category as binary products and equalizers, then it has pullbacks.
Also, if a category has binary coproducts and coequalizers, then it has pushouts
-/
open category_theory
namespace category_theory.limits
/-- If the product `X ⨯ Y` and the equalizer of `π₁ ≫ f` and `π₂ ≫ g` exist, then the
pullback of `f` and `g` exists: It is given by composing the equalizer with the projections. -/
def has_limit_cospan_of_has_limit_pair_of_has_limit_parallel_pair
{C : Type u} [𝒞 : category.{v} C] {X Y Z : C} (f : X ⟶ Z) (g : Y ⟶ Z) [has_limit (pair X Y)]
[has_limit (parallel_pair (prod.fst ≫ f) (prod.snd ≫ g))] : has_limit (cospan f g) :=
let π₁ : X ⨯ Y ⟶ X := prod.fst, π₂ : X ⨯ Y ⟶ Y := prod.snd, e := equalizer.ι (π₁ ≫ f) (π₂ ≫ g) in
{ cone := pullback_cone.mk (e ≫ π₁) (e ≫ π₂) $ by simp only [category.assoc, equalizer.condition],
is_limit := pullback_cone.is_limit.mk _
(λ s, equalizer.lift (prod.lift (s.π.app walking_cospan.left)
(s.π.app walking_cospan.right)) $ by
rw [←category.assoc, limit.lift_π, ←category.assoc, limit.lift_π];
exact pullback_cone.condition _)
(by simp) (by simp) $ λ s m h, by { ext,
{ simpa using h walking_cospan.left },
{ simpa using h walking_cospan.right } } }
section
local attribute [instance] has_limit_cospan_of_has_limit_pair_of_has_limit_parallel_pair
/-- If a category has all binary products and all equalizers, then it also has all pullbacks.
As usual, this is not an instance, since there may be a more direct way to construct
pullbacks. -/
def has_pullbacks_of_has_binary_products_of_has_equalizers
(C : Type u) [𝒞 : category.{v} C] [has_binary_products.{v} C] [has_equalizers.{v} C] :
has_pullbacks.{v} C :=
has_pullbacks_of_has_limit_cospan C
end
/-- If the coproduct `Y ⨿ Z` and the coequalizer of `f ≫ ι₁` and `g ≫ ι₂` exist, then the
pushout of `f` and `g` exists: It is given by composing the inclusions with the coequalizer. -/
def has_colimit_span_of_has_colimit_pair_of_has_colimit_parallel_pair
{C : Type u} [𝒞 : category.{v} C] {X Y Z : C} (f : X ⟶ Y) (g : X ⟶ Z) [has_colimit (pair Y Z)]
[has_colimit (parallel_pair (f ≫ coprod.inl) (g ≫ coprod.inr))] : has_colimit (span f g) :=
let ι₁ : Y ⟶ Y ⨿ Z := coprod.inl, ι₂ : Z ⟶ Y ⨿ Z := coprod.inr,
c := coequalizer.π (f ≫ ι₁) (g ≫ ι₂) in
{ cocone := pushout_cocone.mk (ι₁ ≫ c) (ι₂ ≫ c) $
by rw [←category.assoc, ←category.assoc, coequalizer.condition],
is_colimit := pushout_cocone.is_colimit.mk _
(λ s, coequalizer.desc (coprod.desc (s.ι.app walking_span.left)
(s.ι.app walking_span.right)) $ by
rw [category.assoc, colimit.ι_desc, category.assoc, colimit.ι_desc];
exact pushout_cocone.condition _)
(by simp) (by simp) $ λ s m h, by { ext,
{ simpa using h walking_span.left },
{ simpa using h walking_span.right } } }
section
local attribute [instance] has_colimit_span_of_has_colimit_pair_of_has_colimit_parallel_pair
/-- If a category has all binary coproducts and all coequalizers, then it also has all pushouts.
As usual, this is not an instance, since there may be a more direct way to construct
pushouts. -/
def has_pushouts_of_has_binary_coproducts_of_has_coequalizers
(C : Type u) [𝒞 : category.{v} C] [has_binary_coproducts.{v} C] [has_coequalizers.{v} C] :
has_pushouts.{v} C :=
has_pushouts_of_has_colimit_span C
end
end category_theory.limits
|
54dea1150bb764dd07581594fa4e231d4c9fd7fe | b3fced0f3ff82d577384fe81653e47df68bb2fa1 | /src/linear_algebra/sesquilinear_form.lean | 24ecff73016a3b3842bdab71610454c657ce797b | [
"Apache-2.0"
] | permissive | ratmice/mathlib | 93b251ef5df08b6fd55074650ff47fdcc41a4c75 | 3a948a6a4cd5968d60e15ed914b1ad2f4423af8d | refs/heads/master | 1,599,240,104,318 | 1,572,981,183,000 | 1,572,981,183,000 | 219,830,178 | 0 | 0 | Apache-2.0 | 1,572,980,897,000 | 1,572,980,896,000 | null | UTF-8 | Lean | false | false | 8,625 | lean | /-
Copyright (c) 2018 Andreas Swerdlow. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Andreas Swerdlow
-/
import algebra.module ring_theory.maps
/-!
# Sesquilinear form
This file defines a bilinear form over a module. The definition requires a ring antiautomorphism
on the scalar ring, which comes from the file ring_theory.involution. Basic ideas such as
orthogonality are also introduced.
A sesquilinear form on an R-module M, is a function from M x M to R, that is linear in the first argument
and antilinear in the second, with respect to an antiautomorphism on R (an antiisomorphism from R to R).
## Notations
Given any term S of type sesq_form, due to a coercion, can use the notation S x y to
refer to the function field, ie. S x y = S.bilin x y.
## References
* https://en.wikipedia.org/wiki/Sesquilinear_form#Over_arbitrary_rings
## Tags
Sesquilinear form,
-/
open ring_anti_equiv
universes u v
/-- A sesquilinear form over a module -/
structure sesq_form (R : Type u) (M : Type v) [ring R] (I : ring_anti_equiv R R) [add_comm_group M] [module R M] :=
(sesq : M → M → R)
(sesq_add_left : ∀ (x y z : M), sesq (x + y) z = sesq x z + sesq y z)
(sesq_smul_left : ∀ (a : R) (x y : M), sesq (a • x) y = a * (sesq x y))
(sesq_add_right : ∀ (x y z : M), sesq x (y + z) = sesq x y + sesq x z)
(sesq_smul_right : ∀ (a : R) (x y : M), sesq x (a • y) = (I a) * (sesq x y))
namespace sesq_form
section general_ring
variables {R : Type u} {M : Type v} [ring R] [add_comm_group M] [module R M] {I : ring_anti_equiv R R} {S : sesq_form R M I}
instance : has_coe_to_fun (sesq_form R M I) :=
⟨_, λ S, S.sesq⟩
lemma add_left (x y z : M) : S (x + y) z = S x z + S y z := sesq_add_left S x y z
lemma smul_left (a : R) (x y : M) : S (a • x) y = a * (S x y) := sesq_smul_left S a x y
lemma add_right (x y z : M) : S x (y + z) = S x y + S x z := sesq_add_right S x y z
lemma smul_right (a : R) (x y : M) : S x (a • y) = (I a) * (S x y) := sesq_smul_right S a x y
lemma zero_left (x : M) :
S 0 x = 0 := by {rw [←@zero_smul R _ _ _ _ (0 : M), smul_left, zero_mul]}
lemma zero_right (x : M) :
S x 0 = 0 := by rw [←@zero_smul _ _ _ _ _ (0 : M), smul_right, map_zero, ring.zero_mul]
lemma neg_left (x y : M) :
S (-x) y = -(S x y) := by rw [←@neg_one_smul R _ _, smul_left, neg_one_mul]
lemma neg_right (x y : M) :
S x (-y) = -(S x y) := by rw [←@neg_one_smul R _ _, smul_right, map_neg_one, neg_one_mul]
lemma sub_left (x y z : M) :
S (x - y) z = S x z - S y z := by rw [sub_eq_add_neg, add_left, neg_left]; refl
lemma sub_right (x y z : M) :
S x (y - z) = S x y - S x z := by rw [sub_eq_add_neg, add_right, neg_right]; refl
variable {D : sesq_form R M I}
@[extensionality] lemma ext (H : ∀ (x y : M), S x y = D x y) : S = D := by {cases S, cases D, congr, funext, exact H _ _}
instance : add_comm_group (sesq_form R M I) :=
{ add := λ S D, { sesq := λ x y, S x y + D x y,
sesq_add_left := λ x y z, by {rw add_left, rw add_left, simp},
sesq_smul_left := λ a x y, by {rw [smul_left, smul_left, mul_add]},
sesq_add_right := λ x y z, by {rw add_right, rw add_right, simp},
sesq_smul_right := λ a x y, by {rw [smul_right, smul_right, mul_add]} },
add_assoc := by {intros, ext, unfold coe_fn has_coe_to_fun.coe sesq coe_fn has_coe_to_fun.coe sesq, rw add_assoc},
zero := { sesq := λ x y, 0,
sesq_add_left := λ x y z, (add_zero 0).symm,
sesq_smul_left := λ a x y, (mul_zero a).symm,
sesq_add_right := λ x y z, (zero_add 0).symm,
sesq_smul_right := λ a x y, (mul_zero (I a)).symm },
zero_add := by {intros, ext, unfold coe_fn has_coe_to_fun.coe sesq, rw zero_add},
add_zero := by {intros, ext, unfold coe_fn has_coe_to_fun.coe sesq, rw add_zero},
neg := λ S, { sesq := λ x y, - (S.1 x y),
sesq_add_left := λ x y z, by rw [sesq_add_left, neg_add],
sesq_smul_left := λ a x y, by rw [sesq_smul_left, mul_neg_eq_neg_mul_symm],
sesq_add_right := λ x y z, by rw [sesq_add_right, neg_add],
sesq_smul_right := λ a x y, by rw [sesq_smul_right, mul_neg_eq_neg_mul_symm] },
add_left_neg := by {intros, ext, unfold coe_fn has_coe_to_fun.coe sesq, rw neg_add_self},
add_comm := by {intros, ext, unfold coe_fn has_coe_to_fun.coe sesq, rw add_comm} }
/-- The proposition that two elements of a sesquilinear form space are orthogonal -/
def is_ortho (S : sesq_form R M I) (x y : M) : Prop :=
S x y = 0
lemma ortho_zero (x : M) :
is_ortho S (0 : M) x := zero_left x
end general_ring
section comm_ring
variables {R : Type*} [comm_ring R] {M : Type v} [add_comm_group M] [module R M]
{J : ring_anti_equiv R R} (F : sesq_form R M J) (f : M → M)
instance to_module : module R (sesq_form R M J) :=
{ smul := λ c S, { sesq := λ x y, c * S x y,
sesq_add_left := λ x y z, by {unfold coe_fn has_coe_to_fun.coe sesq, rw [sesq_add_left, left_distrib]},
sesq_smul_left := λ a x y, by {unfold coe_fn has_coe_to_fun.coe sesq, rw [sesq_smul_left, ←mul_assoc, mul_comm c, mul_assoc]},
sesq_add_right := λ x y z, by {unfold coe_fn has_coe_to_fun.coe sesq, rw [sesq_add_right, left_distrib]},
sesq_smul_right := λ a x y, by {unfold coe_fn has_coe_to_fun.coe sesq, rw [sesq_smul_right, ←mul_assoc, mul_comm c, mul_assoc], refl} },
smul_add := λ c S D, by {ext, unfold coe_fn has_coe_to_fun.coe sesq, rw left_distrib},
add_smul := λ c S D, by {ext, unfold coe_fn has_coe_to_fun.coe sesq, rw right_distrib},
mul_smul := λ a c D, by {ext, unfold coe_fn has_coe_to_fun.coe sesq, rw mul_assoc},
one_smul := λ S, by {ext, unfold coe_fn has_coe_to_fun.coe sesq, rw one_mul},
zero_smul := λ S, by {ext, unfold coe_fn has_coe_to_fun.coe sesq, rw zero_mul},
smul_zero := λ S, by {ext, unfold coe_fn has_coe_to_fun.coe sesq, rw mul_zero} }
end comm_ring
section domain
variables {R : Type*} [domain R]
{M : Type v} [add_comm_group M] [module R M]
{K : ring_anti_equiv R R} {G : sesq_form R M K}
theorem ortho_smul_left {x y : M} {a : R} (ha : a ≠ 0) :
(is_ortho G x y) ↔ (is_ortho G (a • x) y) :=
begin
dunfold is_ortho,
split; intro H,
{ rw [smul_left, H, ring.mul_zero] },
{ rw [smul_left, mul_eq_zero] at H,
cases H,
{ trivial },
{ exact H }}
end
theorem ortho_smul_right {x y : M} {a : R} (ha : a ≠ 0) :
(is_ortho G x y) ↔ (is_ortho G x (a • y)) :=
begin
dunfold is_ortho,
split; intro H,
{ rw [smul_right, H, ring.mul_zero] },
{ rw [smul_right, mul_eq_zero] at H,
cases H,
{ rw map_zero_iff at H, trivial },
{ exact H }}
end
end domain
end sesq_form
namespace refl_sesq_form
open refl_sesq_form sesq_form
variables {R : Type*} {M : Type*} [ring R] [add_comm_group M] [module R M] {I : ring_anti_equiv R R} {S : sesq_form R M I}
/-- The proposition that a sesquilinear form is reflexive -/
def is_refl (S : sesq_form R M I) : Prop := ∀ (x y : M), S x y = 0 → S y x = 0
variable (H : is_refl S)
lemma eq_zero : ∀ {x y : M}, S x y = 0 → S y x = 0 := λ x y, H x y
lemma ortho_sym {x y : M} :
is_ortho S x y ↔ is_ortho S y x := ⟨eq_zero H, eq_zero H⟩
end refl_sesq_form
namespace sym_sesq_form
open sym_sesq_form sesq_form
variables {R : Type*} {M : Type*} [ring R] [add_comm_group M] [module R M] {I : ring_anti_equiv R R} {S : sesq_form R M I}
/-- The proposition that a sesquilinear form is symmetric -/
def is_sym (S : sesq_form R M I) : Prop := ∀ (x y : M), I (S x y) = S y x
variable (H : is_sym S)
include H
lemma sym (x y : M) : I (S x y) = S y x := H x y
lemma is_refl : refl_sesq_form.is_refl S := λ x y H1, by rw [←H, map_zero_iff, H1]
lemma ortho_sym {x y : M} :
is_ortho S x y ↔ is_ortho S y x := refl_sesq_form.ortho_sym (is_refl H)
end sym_sesq_form
namespace alt_sesq_form
open alt_sesq_form sesq_form
variables {R : Type*} {M : Type*} [ring R] [add_comm_group M] [module R M] {I : ring_anti_equiv R R} {S : sesq_form R M I}
/-- The proposition that a sesquilinear form is alternating -/
def is_alt (S : sesq_form R M I) : Prop := ∀ (x : M), S x x = 0
variable (H : is_alt S)
include H
lemma self_eq_zero (x : M) : S x x = 0 := H x
lemma neg (x y : M) :
- S x y = S y x :=
begin
have H1 : S (x + y) (x + y) = 0,
{ exact self_eq_zero H (x + y) },
rw [add_left, add_right, add_right,
self_eq_zero H, self_eq_zero H, ring.zero_add,
ring.add_zero, add_eq_zero_iff_neg_eq] at H1,
exact H1,
end
end alt_sesq_form
|
cb64c32c7846575d6a500b10740b653c67f11ea4 | ba4794a0deca1d2aaa68914cd285d77880907b5c | /experiments/bool_le_induction_example.lean | 28288808e202ee39a828ce581768c55daf2223a3 | [
"Apache-2.0"
] | permissive | ChrisHughes24/natural_number_game | c7c00aa1f6a95004286fd456ed13cf6e113159ce | 9d09925424da9f6275e6cfe427c8bcf12bb0944f | refs/heads/master | 1,600,715,773,528 | 1,573,910,462,000 | 1,573,910,462,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 2,097 | lean | -- random experiments that predate [less_leaky] approach
import tactic.linarith -- any import is fine
@[derive decidable_eq]
inductive mybool
| ff : mybool
| tt : mybool
namespace mybool
inductive le : mybool → mybool → Prop
| f_le_f : le ff ff
| f_le_t : le ff tt
| t_le_t : le tt tt
-- notation
instance : has_le mybool := ⟨mybool.le⟩
-- I now never want to see `le` ever ever again.
open le
-- Could I have generated this automatically?
instance decidable_le : ∀ a b : mybool, decidable (a ≤ b) :=
λ a b, mybool.rec_on a (mybool.rec_on b (is_true f_le_f) $ is_true f_le_t) $
mybool.rec_on b (is_false $ λ h, by cases h) $ is_true t_le_t
instance decidable_le' : ∀ a b : mybool, decidable (a ≤ b) :=
λ a b, begin
cases a; cases b;
-- just work it out Lean
try {exact is_true t_le_t};
try {exact is_true f_le_t};
try {exact is_true f_le_f};
try {exact (is_false $ λ h, by cases h)}
end
theorem induction (a b : mybool) (h : a ≤ b) (P : Π (c d : mybool), Prop)
: P ff ff → P ff tt → P tt tt → P a b := λ h_ff_ff h_ff_tt h_tt_tt,
begin
cases a;cases b,
exact h_ff_ff,
exact h_ff_tt,
cases h,
exact h_tt_tt,
end
example (a b : mybool) (h : a ≤ b) (P : Π (a b : mybool), Prop)
-- possible other hypotheses here
: P a b :=
begin
cases a; cases b; cases h,
-- is there a tactic of the form `thing h` which does the same thing?
sorry, sorry, sorry
end
-- These presumably could have been auto-generated but I didn't want
-- to clog up the code with weird @isms
theorem le_refl (a : mybool) : a ≤ a :=
begin
cases a; exact dec_trivial,
-- Is there just one tactic which will do this?
end
theorem le_trans {a b c : mybool} (hab : a ≤ b) (hbc : b ≤ c) : a ≤ c :=
begin
cases a;cases b;cases c; cases hab; cases hbc;
exact dec_trivial,
-- Is there just one tactic which will do this?
end
theorem le_antisymm {a b : mybool} (hab : a ≤ b) (hba : b ≤ a) : a = b :=
begin
cases a; cases b; cases hab; cases hba; exact dec_trivial,
-- Is there just one tactic which will do this?
end
end mybool |
d1fecaad7b37cdf060f2d6919e410901b926d37b | f618aea02cb4104ad34ecf3b9713065cc0d06103 | /src/number_theory/sum_two_squares.lean | 944deff199c31bb04c9a51e46897507f107a045e | [
"Apache-2.0"
] | permissive | joehendrix/mathlib | 84b6603f6be88a7e4d62f5b1b0cbb523bb82b9a5 | c15eab34ad754f9ecd738525cb8b5a870e834ddc | refs/heads/master | 1,589,606,591,630 | 1,555,946,393,000 | 1,555,946,393,000 | 182,813,854 | 0 | 0 | null | 1,555,946,309,000 | 1,555,946,308,000 | null | UTF-8 | Lean | false | false | 3,207 | lean | /-
Copyright (c) 2019 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Chris Hughes
Proof of Fermat's theorem on the sum of two squares. Every prime congruent to 1 mod 4 is the sum
of two squares
-/
import data.zsqrtd.gaussian_int data.zmod.quadratic_reciprocity ring_theory.principal_ideal_domain
open gaussian_int principal_ideal_domain zsqrtd
local attribute [instance, priority 0] nat.cast_coe
local notation `ℤ[i]` := gaussian_int
namespace nat
namespace prime
lemma sum_two_squares {p : ℕ} (hp : p.prime) (hp1 : p % 4 = 1) :
∃ a b : ℕ, a ^ 2 + b ^ 2 = p :=
let ⟨k, hk⟩ := (zmodp.exists_pow_two_eq_neg_one_iff_mod_four_ne_three hp).2 $
by rw hp1; exact dec_trivial in
have hpk : p ∣ k.val ^ 2 + 1,
by rw [← zmodp.eq_zero_iff_dvd_nat hp]; simp *,
have hkmul : (k.val ^ 2 + 1 : ℤ[i]) = ⟨k.val, 1⟩ * ⟨k.val, -1⟩ :=
by simp [_root_.pow_two, zsqrtd.ext],
have hpne1 : p ≠ 1, from (ne_of_lt (hp.gt_one)).symm,
have hkltp : 1 + k.val * k.val < p * p,
from calc 1 + k.val * k.val ≤ k.val + k.val * k.val :
add_le_add_right (nat.pos_of_ne_zero
(λ hk0, by clear_aux_decl; simp [*, nat.pow_succ] at *)) _
... = k.val * (k.val + 1) : by simp [mul_add]
... < p * p : mul_lt_mul k.2 k.2 (nat.succ_pos _) (nat.zero_le _),
have hpk₁ : ¬ (p : ℤ[i]) ∣ ⟨k.val, -1⟩ :=
λ ⟨x, hx⟩, lt_irrefl (p * x : ℤ[i]).norm.nat_abs $
calc (norm (p * x : ℤ[i])).nat_abs = (norm ⟨k.val, -1⟩).nat_abs : by rw hx
... < (norm (p : ℤ[i])).nat_abs : by simpa [norm] using hkltp
... ≤ (norm (p * x : ℤ[i])).nat_abs : norm_le_norm_mul_left _
(λ hx0, (show (-1 : ℤ) ≠ 0, from dec_trivial) $
by simpa [hx0] using congr_arg zsqrtd.im hx),
have hpk₂ : ¬ (p : ℤ[i]) ∣ ⟨k.val, 1⟩ :=
λ ⟨x, hx⟩, lt_irrefl (p * x : ℤ[i]).norm.nat_abs $
calc (norm (p * x : ℤ[i])).nat_abs = (norm ⟨k.val, 1⟩).nat_abs : by rw hx
... < (norm (p : ℤ[i])).nat_abs : by simpa [norm] using hkltp
... ≤ (norm (p * x : ℤ[i])).nat_abs : norm_le_norm_mul_left _
(λ hx0, (show (1 : ℤ) ≠ 0, from dec_trivial) $
by simpa [hx0] using congr_arg zsqrtd.im hx),
have hpu : ¬ is_unit (p : ℤ[i]), from mt norm_eq_one_iff.2 $
by rw [norm_nat_cast, int.nat_abs_mul, nat.mul_eq_one_iff];
exact λ h, (ne_of_lt hp.gt_one).symm h.1,
let ⟨y, hy⟩ := hpk in
have hpi : ¬ irreducible (p : ℤ[i]),
from mt irreducible_iff_prime.1
(λ hp, by have := hp.2.2 ⟨k.val, 1⟩ ⟨k.val, -1⟩
⟨y, by rw [← hkmul, ← nat.cast_mul p, ← hy]; simp⟩;
clear_aux_decl; tauto),
have hab : ∃ a b, (p : ℤ[i]) = a * b ∧ ¬ is_unit a ∧ ¬ is_unit b,
by simpa [irreducible, hpu, classical.not_forall, not_or_distrib] using hpi,
let ⟨a, b, hpab, hau, hbu⟩ := hab in
have hnap : (norm a).nat_abs = p, from ((hp.mul_eq_prime_pow_two_iff
(mt norm_eq_one_iff.1 hau) (mt norm_eq_one_iff.1 hbu)).1 $
by rw [← int.coe_nat_inj', int.coe_nat_pow, _root_.pow_two,
← @norm_nat_cast (-1), hpab];
simp).1,
⟨a.re.nat_abs, a.im.nat_abs, by simpa [nat_abs_norm_eq, pow_two] using hnap⟩
end prime
end nat
|
583b9be27766473c0a0c49d908f6c561e87e73ef | 63abd62053d479eae5abf4951554e1064a4c45b4 | /src/linear_algebra/finite_dimensional.lean | 01c2580b962fc17f923e6cbc54deae0c5dfaa696 | [
"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 | 52,714 | 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 linear_algebra.dimension
import ring_theory.principal_ideal_domain
import algebra.algebra.subalgebra
/-!
# Finite dimensional vector spaces
Definition and basic properties of finite dimensional vector spaces, of their dimensions, and
of linear maps on such spaces.
## Main definitions
Assume `V` is a vector space over a field `K`. There are (at least) three equivalent definitions of
finite-dimensionality of `V`:
- it admits a finite basis.
- it is finitely generated.
- it is noetherian, i.e., every subspace is finitely generated.
We introduce a typeclass `finite_dimensional K V` capturing this property. For ease of transfer of
proof, it is defined using the third point of view, i.e., as `is_noetherian`. However, we prove
that all these points of view are equivalent, with the following lemmas
(in the namespace `finite_dimensional`):
- `exists_is_basis_finite` states that a finite-dimensional vector space has a finite basis
- `of_fintype_basis` states that the existence of a basis indexed by a finite type implies
finite-dimensionality
- `of_finset_basis` states that the existence of a basis indexed by a `finset` implies
finite-dimensionality
- `of_finite_basis` states that the existence of a basis indexed by a finite set implies
finite-dimensionality
- `iff_fg` states that the space is finite-dimensional if and only if it is finitely generated
Also defined is `findim`, the dimension of a finite dimensional space, returning a `nat`,
as opposed to `dim`, which returns a `cardinal`. When the space has infinite dimension, its
`findim` is by convention set to `0`.
Preservation of finite-dimensionality and formulas for the dimension are given for
- submodules
- quotients (for the dimension of a quotient, see `findim_quotient_add_findim`)
- linear equivs, in `linear_equiv.finite_dimensional` and `linear_equiv.findim_eq`
- image under a linear map (the rank-nullity formula is in `findim_range_add_findim_ker`)
Basic properties of linear maps of a finite-dimensional vector space are given. Notably, the
equivalence of injectivity and surjectivity is proved in `linear_map.injective_iff_surjective`,
and the equivalence between left-inverse and right-inverse in `mul_eq_one_comm` and
`comp_eq_id_comm`.
## Implementation notes
Most results are deduced from the corresponding results for the general dimension (as a cardinal),
in `dimension.lean`. Not all results have been ported yet.
One of the characterizations of finite-dimensionality is in terms of finite generation. This
property is currently defined only for submodules, so we express it through the fact that the
maximal submodule (which, as a set, coincides with the whole space) is finitely generated. This is
not very convenient to use, although there are some helper functions. However, this becomes very
convenient when speaking of submodules which are finite-dimensional, as this notion coincides with
the fact that the submodule is finitely generated (as a submodule of the whole space). This
equivalence is proved in `submodule.fg_iff_finite_dimensional`.
-/
universes u v v' w
open_locale classical
open vector_space cardinal submodule module function
variables {K : Type u} {V : Type v} [field K] [add_comm_group V] [vector_space K V]
{V₂ : Type v'} [add_comm_group V₂] [vector_space K V₂]
/-- `finite_dimensional` vector spaces are defined to be noetherian modules.
Use `finite_dimensional.iff_fg` or `finite_dimensional.of_fintype_basis` to prove finite dimension
from a conventional definition. -/
@[reducible] def finite_dimensional (K V : Type*) [field K]
[add_comm_group V] [vector_space K V] := is_noetherian K V
namespace finite_dimensional
open is_noetherian
/-- A vector space is finite-dimensional if and only if its dimension (as a cardinal) is strictly
less than the first infinite cardinal `omega`. -/
lemma finite_dimensional_iff_dim_lt_omega : finite_dimensional K V ↔ dim K V < omega.{v} :=
begin
cases exists_is_basis K V with b hb,
have := is_basis.mk_eq_dim hb,
simp only [lift_id] at this,
rw [← this, lt_omega_iff_fintype, ← @set.set_of_mem_eq _ b, ← subtype.range_coe_subtype],
split,
{ intro, resetI, convert finite_of_linear_independent hb.1, simp },
{ assume hbfinite,
refine @is_noetherian_of_linear_equiv K (⊤ : submodule K V) V _
_ _ _ _ (linear_equiv.of_top _ rfl) (id _),
refine is_noetherian_of_fg_of_noetherian _ ⟨set.finite.to_finset hbfinite, _⟩,
rw [set.finite.coe_to_finset, ← hb.2], refl }
end
/-- The dimension of a finite-dimensional vector space, as a cardinal, is strictly less than the
first infinite cardinal `omega`. -/
lemma dim_lt_omega (K V : Type*) [field K] [add_comm_group V] [vector_space K V] :
∀ [finite_dimensional K V], dim K V < omega.{v} :=
finite_dimensional_iff_dim_lt_omega.1
/-- In a finite dimensional space, there exists a finite basis. A basis is in general given as a
function from an arbitrary type to the vector space. Here, we think of a basis as a set (instead of
a function), and use as parametrizing type this set (and as a function the coercion
`coe : s → V`).
-/
variables (K V)
lemma exists_is_basis_finite [finite_dimensional K V] :
∃ s : set V, (is_basis K (coe : s → V)) ∧ s.finite :=
begin
cases exists_is_basis K V with s hs,
exact ⟨s, hs, finite_of_linear_independent hs.1⟩
end
/-- In a finite dimensional space, there exists a finite basis. Provides the basis as a finset.
This is in contrast to `exists_is_basis_finite`, which provides a set and a `set.finite`.
-/
lemma exists_is_basis_finset [finite_dimensional K V] :
∃ b : finset V, is_basis K (coe : (↑b : set V) → V) :=
begin
obtain ⟨s, s_basis, s_finite⟩ := exists_is_basis_finite K V,
refine ⟨s_finite.to_finset, _⟩,
rw set.finite.coe_to_finset,
exact s_basis,
end
/-- A finite dimensional vector space over a finite field is finite -/
noncomputable def fintype_of_fintype [fintype K] [finite_dimensional K V] : fintype V :=
module.fintype_of_fintype (classical.some_spec (finite_dimensional.exists_is_basis_finset K V) : _)
variables {K V}
/-- A vector space is finite-dimensional if and only if it is finitely generated. As the
finitely-generated property is a property of submodules, we formulate this in terms of the
maximal submodule, equal to the whole space as a set by definition.-/
lemma iff_fg :
finite_dimensional K V ↔ (⊤ : submodule K V).fg :=
begin
split,
{ introI h,
rcases exists_is_basis_finite K V with ⟨s, s_basis, s_finite⟩,
exact ⟨s_finite.to_finset, by { convert s_basis.2, simp }⟩ },
{ rintros ⟨s, hs⟩,
rw [finite_dimensional_iff_dim_lt_omega, ← dim_top, ← hs],
exact lt_of_le_of_lt (dim_span_le _) (lt_omega_iff_finite.2 (set.finite_mem_finset s)) }
end
/-- If a vector space has a finite basis, then it is finite-dimensional. -/
lemma of_fintype_basis {ι : Type w} [fintype ι] {b : ι → V} (h : is_basis K b) :
finite_dimensional K V :=
iff_fg.2 $ ⟨finset.univ.image b, by {convert h.2, simp} ⟩
/-- If a vector space has a basis indexed by elements of a finite set, then it is
finite-dimensional. -/
lemma of_finite_basis {ι} {s : set ι} {b : s → V} (h : is_basis K b) (hs : set.finite s) :
finite_dimensional K V :=
by haveI := hs.fintype; exact of_fintype_basis h
/-- If a vector space has a finite basis, then it is finite-dimensional, finset style. -/
lemma of_finset_basis {ι} {s : finset ι} {b : (↑s : set ι) → V} (h : is_basis K b) :
finite_dimensional K V :=
of_finite_basis h s.finite_to_set
/-- A subspace of a finite-dimensional space is also finite-dimensional. -/
instance finite_dimensional_submodule [finite_dimensional K V] (S : submodule K V) :
finite_dimensional K S :=
finite_dimensional_iff_dim_lt_omega.2 (lt_of_le_of_lt (dim_submodule_le _) (dim_lt_omega K V))
/-- A quotient of a finite-dimensional space is also finite-dimensional. -/
instance finite_dimensional_quotient [finite_dimensional K V] (S : submodule K V) :
finite_dimensional K (quotient S) :=
finite_dimensional_iff_dim_lt_omega.2 (lt_of_le_of_lt (dim_quotient_le _) (dim_lt_omega K V))
/-- The dimension of a finite-dimensional vector space as a natural number. Defined by convention to
be `0` if the space is infinite-dimensional. -/
noncomputable def findim (K V : Type*) [field K]
[add_comm_group V] [vector_space K V] : ℕ :=
if h : dim K V < omega.{v} then classical.some (lt_omega.1 h) else 0
/-- In a finite-dimensional space, its dimension (seen as a cardinal) coincides with its `findim`. -/
lemma findim_eq_dim (K : Type u) (V : Type v) [field K]
[add_comm_group V] [vector_space K V] [finite_dimensional K V] :
(findim K V : cardinal.{v}) = dim K V :=
begin
have : findim K V = classical.some (lt_omega.1 (dim_lt_omega K V)) :=
dif_pos (dim_lt_omega K V),
rw this,
exact (classical.some_spec (lt_omega.1 (dim_lt_omega K V))).symm
end
lemma findim_of_infinite_dimensional {K V : Type*} [field K] [add_comm_group V] [vector_space K V]
(h : ¬finite_dimensional K V) : findim K V = 0 :=
dif_neg $ mt finite_dimensional_iff_dim_lt_omega.2 h
/-- If a vector space has a finite basis, then its dimension (seen as a cardinal) is equal to the
cardinality of the basis. -/
lemma dim_eq_card_basis {ι : Type w} [fintype ι] {b : ι → V} (h : is_basis K b) :
dim K V = fintype.card ι :=
by rw [←h.mk_range_eq_dim, cardinal.fintype_card,
set.card_range_of_injective h.injective]
/-- If a vector space has a finite basis, then its dimension is equal to the cardinality of the
basis. -/
lemma findim_eq_card_basis {ι : Type w} [fintype ι] {b : ι → V} (h : is_basis K b) :
findim K V = fintype.card ι :=
begin
haveI : finite_dimensional K V := of_fintype_basis h,
have := dim_eq_card_basis h,
rw ← findim_eq_dim at this,
exact_mod_cast this
end
/-- If a vector space is finite-dimensional, then the cardinality of any basis is equal to its
`findim`. -/
lemma findim_eq_card_basis' [finite_dimensional K V] {ι : Type w} {b : ι → V} (h : is_basis K b) :
(findim K V : cardinal.{w}) = cardinal.mk ι :=
begin
rcases exists_is_basis_finite K V with ⟨s, s_basis, s_finite⟩,
letI: fintype s := s_finite.fintype,
have A : cardinal.mk s = fintype.card s := fintype_card _,
have B : findim K V = fintype.card s := findim_eq_card_basis s_basis,
have C : cardinal.lift.{w v} (cardinal.mk ι) = cardinal.lift.{v w} (cardinal.mk s) :=
mk_eq_mk_of_basis h s_basis,
rw [A, ← B, lift_nat_cast] at C,
have : cardinal.lift.{w v} (cardinal.mk ι) = cardinal.lift.{w v} (findim K V),
by { simp, exact C },
exact (lift_inj.mp this).symm
end
/-- If a vector space has a finite basis, then its dimension is equal to the cardinality of the
basis. This lemma uses a `finset` instead of indexed types. -/
lemma findim_eq_card_finset_basis {b : finset V}
(h : is_basis K (subtype.val : (↑b : set V) -> V)) :
findim K V = finset.card b :=
by { rw [findim_eq_card_basis h, fintype.subtype_card], intros x, refl }
lemma equiv_fin {ι : Type*} [finite_dimensional K V] {v : ι → V} (hv : is_basis K v) :
∃ g : fin (findim K V) ≃ ι, is_basis K (v ∘ g) :=
begin
have : (cardinal.mk (fin $ findim K V)).lift = (cardinal.mk ι).lift,
{ simp [cardinal.mk_fin (findim K V), ← findim_eq_card_basis' hv] },
rcases cardinal.lift_mk_eq.mp this with ⟨g⟩,
exact ⟨g, hv.comp _ g.bijective⟩
end
variables (K V)
lemma fin_basis [finite_dimensional K V] : ∃ v : fin (findim K V) → V, is_basis K v :=
let ⟨B, hB, B_fin⟩ := exists_is_basis_finite K V, ⟨g, hg⟩ := finite_dimensional.equiv_fin hB in
⟨coe ∘ g, hg⟩
variables {K V}
lemma cardinal_mk_le_findim_of_linear_independent
[finite_dimensional K V] {ι : Type w} {b : ι → V} (h : linear_independent K b) :
cardinal.mk ι ≤ findim K V :=
begin
rw ← lift_le.{_ (max v w)},
simpa [← findim_eq_dim K V] using
cardinal_lift_le_dim_of_linear_independent.{_ _ _ (max v w)} h
end
lemma fintype_card_le_findim_of_linear_independent
[finite_dimensional K V] {ι : Type*} [fintype ι] {b : ι → V} (h : linear_independent K b) :
fintype.card ι ≤ findim K V :=
by simpa [fintype_card] using cardinal_mk_le_findim_of_linear_independent h
lemma finset_card_le_findim_of_linear_independent [finite_dimensional K V] {b : finset V}
(h : linear_independent K (λ x, x : (↑b : set V) → V)) :
b.card ≤ findim K V :=
begin
rw ←fintype.card_coe,
exact fintype_card_le_findim_of_linear_independent h,
end
lemma lt_omega_of_linear_independent {ι : Type w} [finite_dimensional K V]
{v : ι → V} (h : linear_independent K v) :
cardinal.mk ι < cardinal.omega :=
begin
apply cardinal.lift_lt.1,
apply lt_of_le_of_lt,
apply linear_independent_le_dim h,
rw [←findim_eq_dim, cardinal.lift_omega, cardinal.lift_nat_cast],
apply cardinal.nat_lt_omega,
end
lemma not_linear_independent_of_infinite {ι : Type w} [inf : infinite ι] [finite_dimensional K V]
(v : ι → V) : ¬ linear_independent K v :=
begin
intro h_lin_indep,
have : ¬ omega ≤ mk ι := not_le.mpr (lt_omega_of_linear_independent h_lin_indep),
have : omega ≤ mk ι := infinite_iff.mp inf,
contradiction
end
/-- A finite dimensional space has positive `findim` iff it has a nonzero element. -/
lemma findim_pos_iff_exists_ne_zero [finite_dimensional K V] : 0 < findim K V ↔ ∃ x : V, x ≠ 0 :=
iff.trans (by { rw ← findim_eq_dim, norm_cast }) (@dim_pos_iff_exists_ne_zero K V _ _ _)
/-- A finite dimensional space has positive `findim` iff it is nontrivial. -/
lemma findim_pos_iff [finite_dimensional K V] : 0 < findim K V ↔ nontrivial V :=
iff.trans (by { rw ← findim_eq_dim, norm_cast }) (@dim_pos_iff_nontrivial K V _ _ _)
/-- A nontrivial finite dimensional space has positive `findim`. -/
lemma findim_pos [finite_dimensional K V] [h : nontrivial V] : 0 < findim K V :=
findim_pos_iff.mpr h
section
open_locale big_operators
open finset
/--
If a finset has cardinality larger than the dimension of the space,
then there is a nontrivial linear relation amongst its elements.
-/
lemma exists_nontrivial_relation_of_dim_lt_card
[finite_dimensional K V] {t : finset V} (h : findim K V < t.card) :
∃ f : V → K, ∑ e in t, f e • e = 0 ∧ ∃ x ∈ t, f x ≠ 0 :=
begin
have := mt finset_card_le_findim_of_linear_independent (by { simpa using h }),
rw linear_dependent_iff at this,
obtain ⟨s, g, sum, z, zm, nonzero⟩ := this,
-- Now we have to extend `g` to all of `t`, then to all of `V`.
let f : V → K := λ x, if h : x ∈ t then if (⟨x, h⟩ : (↑t : set V)) ∈ s then g ⟨x, h⟩ else 0 else 0,
-- and finally clean up the mess caused by the extension.
refine ⟨f, _, _⟩,
{ dsimp [f],
rw ← sum,
fapply sum_bij_ne_zero (λ v hvt _, (⟨v, hvt⟩ : {v // v ∈ t})),
{ intros v hvt H, dsimp,
rw [dif_pos hvt] at H,
contrapose! H,
rw [if_neg H, zero_smul], },
{ intros _ _ _ _ _ _, exact subtype.mk.inj, },
{ intros b hbs hb,
use b,
simpa only [hbs, exists_prop, dif_pos, mk_coe, and_true, if_true, finset.coe_mem,
eq_self_iff_true, exists_prop_of_true, ne.def] using hb, },
{ intros a h₁, dsimp, rw [dif_pos h₁],
intro h₂, rw [if_pos], contrapose! h₂,
rw [if_neg h₂, zero_smul], }, },
{ refine ⟨z, z.2, _⟩, dsimp only [f], erw [dif_pos z.2, if_pos]; rwa [subtype.coe_eta] },
end
/--
If a finset has cardinality larger than `findim + 1`,
then there is a nontrivial linear relation amongst its elements,
such that the coefficients of the relation sum to zero.
-/
lemma exists_nontrivial_relation_sum_zero_of_dim_succ_lt_card
[finite_dimensional K V] {t : finset V} (h : findim K V + 1 < t.card) :
∃ f : V → K, ∑ e in t, f e • e = 0 ∧ ∑ e in t, f e = 0 ∧ ∃ x ∈ t, f x ≠ 0 :=
begin
-- Pick an element x₀ ∈ t,
have card_pos : 0 < t.card := lt_trans (nat.succ_pos _) h,
obtain ⟨x₀, m⟩ := (finset.card_pos.1 card_pos).bex,
-- and apply the previous lemma to the {xᵢ - x₀}
let shift : V ↪ V := ⟨λ x, x - x₀, add_left_injective (-x₀)⟩,
let t' := (t.erase x₀).map shift,
have h' : findim K V < t'.card,
{ simp only [t', card_map, finset.card_erase_of_mem m],
exact nat.lt_pred_iff.mpr h, },
-- to obtain a function `g`.
obtain ⟨g, gsum, x₁, x₁_mem, nz⟩ := exists_nontrivial_relation_of_dim_lt_card h',
-- Then obtain `f` by translating back by `x₀`,
-- and setting the value of `f` at `x₀` to ensure `∑ e in t, f e = 0`.
let f : V → K := λ z, if z = x₀ then - ∑ z in (t.erase x₀), g (z - x₀) else g (z - x₀),
refine ⟨f, _ ,_ ,_⟩,
-- After this, it's a matter of verifiying the properties,
-- based on the corresponding properties for `g`.
{ show ∑ (e : V) in t, f e • e = 0,
-- We prove this by splitting off the `x₀` term of the sum,
-- which is itself a sum over `t.erase x₀`,
-- combining the two sums, and
-- observing that after reindexing we have exactly
-- ∑ (x : V) in t', g x • x = 0.
simp only [f],
conv_lhs { apply_congr, skip, rw [ite_smul], },
rw [finset.sum_ite],
conv { congr, congr, apply_congr, simp [filter_eq', m], },
conv { congr, congr, skip, apply_congr, simp [filter_ne'], },
rw [sum_singleton, neg_smul, add_comm, ←sub_eq_add_neg, sum_smul, ←sum_sub_distrib],
simp only [←smul_sub],
-- At the end we have to reindex the sum, so we use `change` to
-- express the summand using `shift`.
change (∑ (x : V) in t.erase x₀, (λ e, g e • e) (shift x)) = 0,
rw ←sum_map _ shift,
exact gsum, },
{ show ∑ (e : V) in t, f e = 0,
-- Again we split off the `x₀` term,
-- observing that it exactly cancels the other terms.
rw [← insert_erase m, sum_insert (not_mem_erase x₀ t)],
dsimp [f],
rw [if_pos rfl],
conv_lhs { congr, skip, apply_congr, skip, rw if_neg (show x ≠ x₀, from (mem_erase.mp H).1), },
exact neg_add_self _, },
{ show ∃ (x : V) (H : x ∈ t), f x ≠ 0,
-- We can use x₁ + x₀.
refine ⟨x₁ + x₀, _, _⟩,
{ rw finset.mem_map at x₁_mem,
rcases x₁_mem with ⟨x₁, x₁_mem, rfl⟩,
rw mem_erase at x₁_mem,
simp only [x₁_mem, sub_add_cancel, function.embedding.coe_fn_mk], },
{ dsimp only [f],
rwa [if_neg, add_sub_cancel],
rw [add_left_eq_self], rintro rfl,
simpa only [sub_eq_zero, exists_prop, finset.mem_map, embedding.coe_fn_mk, eq_self_iff_true,
mem_erase, not_true, exists_eq_right, ne.def, false_and] using x₁_mem, } },
end
section
variables {L : Type*} [linear_ordered_field L]
variables {W : Type v} [add_comm_group W] [vector_space L W]
/--
A slight strengthening of `exists_nontrivial_relation_sum_zero_of_dim_succ_lt_card`
available when working over an ordered field:
we can ensure a positive coefficient, not just a nonzero coefficient.
-/
lemma exists_relation_sum_zero_pos_coefficient_of_dim_succ_lt_card
[finite_dimensional L W] {t : finset W} (h : findim L W + 1 < t.card) :
∃ f : W → L, ∑ e in t, f e • e = 0 ∧ ∑ e in t, f e = 0 ∧ ∃ x ∈ t, 0 < f x :=
begin
obtain ⟨f, sum, total, nonzero⟩ := exists_nontrivial_relation_sum_zero_of_dim_succ_lt_card h,
exact ⟨f, sum, total, exists_pos_of_sum_zero_of_exists_nonzero f total nonzero⟩,
end
end
end
/-- If a submodule has maximal dimension in a finite dimensional space, then it is equal to the
whole space. -/
lemma eq_top_of_findim_eq [finite_dimensional K V] {S : submodule K V}
(h : findim K S = findim K V) : S = ⊤ :=
begin
cases exists_is_basis K S with bS hbS,
have : linear_independent K (subtype.val : (subtype.val '' bS : set V) → V),
from @linear_independent.image_subtype _ _ _ _ _ _ _ _ _
(submodule.subtype S) hbS.1 (by simp),
cases exists_subset_is_basis this with b hb,
letI : fintype b := classical.choice (finite_of_linear_independent hb.2.1),
letI : fintype (subtype.val '' bS) := classical.choice (finite_of_linear_independent this),
letI : fintype bS := classical.choice (finite_of_linear_independent hbS.1),
have : subtype.val '' bS = b, from set.eq_of_subset_of_card_le hb.1
(by rw [set.card_image_of_injective _ subtype.val_injective, ← findim_eq_card_basis hbS,
← findim_eq_card_basis hb.2, h]; apply_instance),
erw [← hb.2.2, subtype.range_coe, ← this, ← subtype_eq_val, span_image],
have := hbS.2,
erw [subtype.range_coe] at this,
rw [this, map_top (submodule.subtype S), range_subtype],
end
variable (K)
/-- A field is one-dimensional as a vector space over itself. -/
@[simp] lemma findim_of_field : findim K K = 1 :=
begin
have := dim_of_field K,
rw [← findim_eq_dim] at this,
exact_mod_cast this
end
/-- The vector space of functions on a fintype has finite dimension. -/
instance finite_dimensional_fintype_fun {ι : Type*} [fintype ι] :
finite_dimensional K (ι → K) :=
by { rw [finite_dimensional_iff_dim_lt_omega, dim_fun'], exact nat_lt_omega _ }
/-- The vector space of functions on a fintype ι has findim equal to the cardinality of ι. -/
@[simp] lemma findim_fintype_fun_eq_card {ι : Type v} [fintype ι] :
findim K (ι → K) = fintype.card ι :=
begin
have : vector_space.dim K (ι → K) = fintype.card ι := dim_fun',
rwa [← findim_eq_dim, nat_cast_inj] at this,
end
/-- The vector space of functions on `fin n` has findim equal to `n`. -/
@[simp] lemma findim_fin_fun {n : ℕ} : findim K (fin n → K) = n :=
by simp
/-- The submodule generated by a finite set is finite-dimensional. -/
theorem span_of_finite {A : set V} (hA : set.finite A) : finite_dimensional K (submodule.span K A) :=
is_noetherian_span_of_finite K hA
/-- The submodule generated by a single element is finite-dimensional. -/
instance (x : V) : finite_dimensional K (submodule.span K ({x} : set V)) := by {apply span_of_finite, simp}
end finite_dimensional
section zero_dim
open vector_space finite_dimensional
lemma finite_dimensional_of_dim_eq_zero (h : vector_space.dim K V = 0) : finite_dimensional K V :=
by rw [finite_dimensional_iff_dim_lt_omega, h]; exact cardinal.omega_pos
lemma finite_dimensional_of_dim_eq_one (h : vector_space.dim K V = 1) : finite_dimensional K V :=
by rw [finite_dimensional_iff_dim_lt_omega, h]; exact one_lt_omega
lemma findim_eq_zero_of_dim_eq_zero [finite_dimensional K V] (h : vector_space.dim K V = 0) :
findim K V = 0 :=
begin
convert findim_eq_dim K V,
rw h, norm_cast
end
variables (K V)
lemma finite_dimensional_bot : finite_dimensional K (⊥ : submodule K V) :=
finite_dimensional_of_dim_eq_zero $ by simp
@[simp] lemma findim_bot : findim K (⊥ : submodule K V) = 0 :=
begin
haveI := finite_dimensional_bot K V,
convert findim_eq_dim K (⊥ : submodule K V),
rw dim_bot, norm_cast
end
variables {K V}
lemma bot_eq_top_of_dim_eq_zero (h : vector_space.dim K V = 0) : (⊥ : submodule K V) = ⊤ :=
begin
haveI := finite_dimensional_of_dim_eq_zero h,
apply eq_top_of_findim_eq,
rw [findim_bot, findim_eq_zero_of_dim_eq_zero h]
end
@[simp] theorem dim_eq_zero {S : submodule K V} : dim K S = 0 ↔ S = ⊥ :=
⟨λ h, (submodule.eq_bot_iff _).2 $ λ x hx, congr_arg subtype.val $
((submodule.eq_bot_iff _).1 $ eq.symm $ bot_eq_top_of_dim_eq_zero h) ⟨x, hx⟩ submodule.mem_top,
λ h, by rw [h, dim_bot]⟩
@[simp] theorem findim_eq_zero {S : submodule K V} [finite_dimensional K S] : findim K S = 0 ↔ S = ⊥ :=
by rw [← dim_eq_zero, ← findim_eq_dim, ← @nat.cast_zero cardinal, cardinal.nat_cast_inj]
end zero_dim
namespace submodule
open finite_dimensional
/-- A submodule is finitely generated if and only if it is finite-dimensional -/
theorem fg_iff_finite_dimensional (s : submodule K V) :
s.fg ↔ finite_dimensional K s :=
⟨λh, is_noetherian_of_fg_of_noetherian s h,
λh, by { rw ← map_subtype_top s, exact fg_map (iff_fg.1 h) }⟩
/-- A submodule contained in a finite-dimensional submodule is
finite-dimensional. -/
lemma finite_dimensional_of_le {S₁ S₂ : submodule K V} [finite_dimensional K S₂] (h : S₁ ≤ S₂) :
finite_dimensional K S₁ :=
finite_dimensional_iff_dim_lt_omega.2 (lt_of_le_of_lt (dim_le_of_submodule _ _ h)
(dim_lt_omega K S₂))
/-- The inf of two submodules, the first finite-dimensional, is
finite-dimensional. -/
instance finite_dimensional_inf_left (S₁ S₂ : submodule K V) [finite_dimensional K S₁] :
finite_dimensional K (S₁ ⊓ S₂ : submodule K V) :=
finite_dimensional_of_le inf_le_left
/-- The inf of two submodules, the second finite-dimensional, is
finite-dimensional. -/
instance finite_dimensional_inf_right (S₁ S₂ : submodule K V) [finite_dimensional K S₂] :
finite_dimensional K (S₁ ⊓ S₂ : submodule K V) :=
finite_dimensional_of_le inf_le_right
/-- The sup of two finite-dimensional submodules is
finite-dimensional. -/
instance finite_dimensional_sup (S₁ S₂ : submodule K V) [h₁ : finite_dimensional K S₁]
[h₂ : finite_dimensional K S₂] : finite_dimensional K (S₁ ⊔ S₂ : submodule K V) :=
begin
rw ←submodule.fg_iff_finite_dimensional at *,
exact submodule.fg_sup h₁ h₂
end
/-- In a finite-dimensional vector space, the dimensions of a submodule and of the corresponding
quotient add up to the dimension of the space. -/
theorem findim_quotient_add_findim [finite_dimensional K V] (s : submodule K V) :
findim K s.quotient + findim K s = findim K V :=
begin
have := dim_quotient_add_dim s,
rw [← findim_eq_dim, ← findim_eq_dim, ← findim_eq_dim] at this,
exact_mod_cast this
end
/-- The dimension of a submodule is bounded by the dimension of the ambient space. -/
lemma findim_le [finite_dimensional K V] (s : submodule K V) : findim K s ≤ findim K V :=
by { rw ← s.findim_quotient_add_findim, exact nat.le_add_left _ _ }
/-- The dimension of a strict submodule is strictly bounded by the dimension of the ambient space. -/
lemma findim_lt [finite_dimensional K V] {s : submodule K V} (h : s < ⊤) :
findim K s < findim K V :=
begin
rw [← s.findim_quotient_add_findim, add_comm],
exact nat.lt_add_of_zero_lt_left _ _ (findim_pos_iff.mpr (quotient.nontrivial_of_lt_top _ h))
end
/-- The dimension of a quotient is bounded by the dimension of the ambient space. -/
lemma findim_quotient_le [finite_dimensional K V] (s : submodule K V) :
findim K s.quotient ≤ findim K V :=
by { rw ← s.findim_quotient_add_findim, exact nat.le_add_right _ _ }
/-- The sum of the dimensions of s + t and s ∩ t is the sum of the dimensions of s and t -/
theorem dim_sup_add_dim_inf_eq (s t : submodule K V) [finite_dimensional K s]
[finite_dimensional K t] : findim K ↥(s ⊔ t) + findim K ↥(s ⊓ t) = findim K ↥s + findim K ↥t :=
begin
have key : dim K ↥(s ⊔ t) + dim K ↥(s ⊓ t) = dim K s + dim K t := dim_sup_add_dim_inf_eq s t,
repeat { rw ←findim_eq_dim at key },
norm_cast at key,
exact key
end
lemma eq_top_of_disjoint [finite_dimensional K V] (s t : submodule K V)
(hdim : findim K s + findim K t = findim K V)
(hdisjoint : disjoint s t) : s ⊔ t = ⊤ :=
begin
have h_findim_inf : findim K ↥(s ⊓ t) = 0,
{ rw [disjoint, le_bot_iff] at hdisjoint,
rw [hdisjoint, findim_bot] },
apply eq_top_of_findim_eq,
rw ←hdim,
convert s.dim_sup_add_dim_inf_eq t,
rw h_findim_inf,
refl,
end
end submodule
namespace linear_equiv
open finite_dimensional
/-- Finite dimensionality is preserved under linear equivalence. -/
protected theorem finite_dimensional (f : V ≃ₗ[K] V₂) [finite_dimensional K V] :
finite_dimensional K V₂ :=
is_noetherian_of_linear_equiv f
/-- The dimension of a finite dimensional space is preserved under linear equivalence. -/
theorem findim_eq (f : V ≃ₗ[K] V₂) [finite_dimensional K V] :
findim K V = findim K V₂ :=
begin
haveI : finite_dimensional K V₂ := f.finite_dimensional,
rcases exists_is_basis_finite K V with ⟨s, s_basis, s_finite⟩,
letI : fintype s := s_finite.fintype,
have A : findim K V = fintype.card s := findim_eq_card_basis s_basis,
have : is_basis K (λx:s, f (subtype.val x)) := f.is_basis s_basis,
have B : findim K V₂ = fintype.card s := findim_eq_card_basis this,
rw [A, B]
end
end linear_equiv
namespace finite_dimensional
lemma eq_of_le_of_findim_le {S₁ S₂ : submodule K V} [finite_dimensional K S₂] (hle : S₁ ≤ S₂)
(hd : findim K S₂ ≤ findim K S₁) : S₁ = S₂ :=
begin
rw ←linear_equiv.findim_eq (submodule.comap_subtype_equiv_of_le hle) at hd,
exact le_antisymm hle (submodule.comap_subtype_eq_top.1 (eq_top_of_findim_eq
(le_antisymm (comap (submodule.subtype S₂) S₁).findim_le hd))),
end
/-- If a submodule is less than or equal to a finite-dimensional
submodule with the same dimension, they are equal. -/
lemma eq_of_le_of_findim_eq {S₁ S₂ : submodule K V} [finite_dimensional K S₂] (hle : S₁ ≤ S₂)
(hd : findim K S₁ = findim K S₂) : S₁ = S₂ :=
eq_of_le_of_findim_le hle hd.ge
end finite_dimensional
namespace linear_map
open finite_dimensional
/-- On a finite-dimensional space, an injective linear map is surjective. -/
lemma surjective_of_injective [finite_dimensional K V] {f : V →ₗ[K] V}
(hinj : injective f) : surjective f :=
begin
have h := dim_eq_of_injective _ hinj,
rw [← findim_eq_dim, ← findim_eq_dim, nat_cast_inj] at h,
exact range_eq_top.1 (eq_top_of_findim_eq h.symm)
end
/-- On a finite-dimensional space, a linear map is injective if and only if it is surjective. -/
lemma injective_iff_surjective [finite_dimensional K V] {f : V →ₗ[K] V} :
injective f ↔ surjective f :=
⟨surjective_of_injective,
λ hsurj, let ⟨g, hg⟩ := f.exists_right_inverse_of_surjective (range_eq_top.2 hsurj) in
have function.right_inverse g f, from linear_map.ext_iff.1 hg,
(left_inverse_of_surjective_of_right_inverse
(surjective_of_injective this.injective) this).injective⟩
lemma ker_eq_bot_iff_range_eq_top [finite_dimensional K V] {f : V →ₗ[K] V} :
f.ker = ⊥ ↔ f.range = ⊤ :=
by rw [range_eq_top, ker_eq_bot, injective_iff_surjective]
/-- In a finite-dimensional space, if linear maps are inverse to each other on one side then they
are also inverse to each other on the other side. -/
lemma mul_eq_one_of_mul_eq_one [finite_dimensional K V] {f g : V →ₗ[K] V} (hfg : f * g = 1) :
g * f = 1 :=
have ginj : injective g, from has_left_inverse.injective
⟨f, (λ x, show (f * g) x = (1 : V →ₗ[K] V) x, by rw hfg; refl)⟩,
let ⟨i, hi⟩ := g.exists_right_inverse_of_surjective
(range_eq_top.2 (injective_iff_surjective.1 ginj)) in
have f * (g * i) = f * 1, from congr_arg _ hi,
by rw [← mul_assoc, hfg, one_mul, mul_one] at this; rwa ← this
/-- In a finite-dimensional space, linear maps are inverse to each other on one side if and only if
they are inverse to each other on the other side. -/
lemma mul_eq_one_comm [finite_dimensional K V] {f g : V →ₗ[K] V} : f * g = 1 ↔ g * f = 1 :=
⟨mul_eq_one_of_mul_eq_one, mul_eq_one_of_mul_eq_one⟩
/-- In a finite-dimensional space, linear maps are inverse to each other on one side if and only if
they are inverse to each other on the other side. -/
lemma comp_eq_id_comm [finite_dimensional K V] {f g : V →ₗ[K] V} : f.comp g = id ↔ g.comp f = id :=
mul_eq_one_comm
/-- The image under an onto linear map of a finite-dimensional space is also finite-dimensional. -/
lemma finite_dimensional_of_surjective [h : finite_dimensional K V]
(f : V →ₗ[K] V₂) (hf : f.range = ⊤) : finite_dimensional K V₂ :=
is_noetherian_of_surjective V f hf
/-- The range of a linear map defined on a finite-dimensional space is also finite-dimensional. -/
instance finite_dimensional_range [h : finite_dimensional K V] (f : V →ₗ[K] V₂) :
finite_dimensional K f.range :=
f.quot_ker_equiv_range.finite_dimensional
/-- rank-nullity theorem : the dimensions of the kernel and the range of a linear map add up to
the dimension of the source space. -/
theorem findim_range_add_findim_ker [finite_dimensional K V] (f : V →ₗ[K] V₂) :
findim K f.range + findim K f.ker = findim K V :=
by { rw [← f.quot_ker_equiv_range.findim_eq], exact submodule.findim_quotient_add_findim _ }
end linear_map
namespace linear_equiv
open finite_dimensional
variables [finite_dimensional K V]
/-- The linear equivalence corresponging to an injective endomorphism. -/
noncomputable def of_injective_endo (f : V →ₗ[K] V) (h_inj : f.ker = ⊥) : V ≃ₗ[K] V :=
(linear_equiv.of_injective f h_inj).trans (linear_equiv.of_top _ (linear_map.ker_eq_bot_iff_range_eq_top.1 h_inj))
lemma of_injective_endo_to_fun (f : V →ₗ[K] V) (h_inj : f.ker = ⊥) :
(of_injective_endo f h_inj).to_fun = f := rfl
lemma of_injective_endo_right_inv (f : V →ₗ[K] V) (h_inj : f.ker = ⊥) :
f * (of_injective_endo f h_inj).symm = 1 :=
begin
ext,
simp only [linear_map.one_app, linear_map.mul_app],
change f ((of_injective_endo f h_inj).symm x) = x,
rw ← linear_equiv.inv_fun_apply (of_injective_endo f h_inj),
apply (of_injective_endo f h_inj).right_inv,
end
lemma of_injective_endo_left_inv (f : V →ₗ[K] V) (h_inj : f.ker = ⊥) :
((of_injective_endo f h_inj).symm : V →ₗ[K] V) * f = 1 :=
begin
ext,
simp only [linear_map.one_app, linear_map.mul_app],
change (of_injective_endo f h_inj).symm (f x) = x,
rw ← linear_equiv.inv_fun_apply (of_injective_endo f h_inj),
apply (of_injective_endo f h_inj).left_inv,
end
end linear_equiv
namespace linear_map
lemma is_unit_iff [finite_dimensional K V] (f : V →ₗ[K] V): is_unit f ↔ f.ker = ⊥ :=
begin
split,
{ intro h_is_unit,
rcases h_is_unit with ⟨u, hu⟩,
rw [←hu, linear_map.ker_eq_bot'],
intros x hx,
change (1 : V →ₗ[K] V) x = 0,
rw ← u.inv_val,
change u.inv (u x) = 0,
simp [hx] },
{ intro h_inj,
use ⟨f, (linear_equiv.of_injective_endo f h_inj).symm.to_linear_map,
linear_equiv.of_injective_endo_right_inv f h_inj, linear_equiv.of_injective_endo_left_inv f h_inj⟩,
refl }
end
end linear_map
open vector_space finite_dimensional
section top
@[simp]
theorem findim_top : findim K (⊤ : submodule K V) = findim K V :=
by { unfold findim, simp [dim_top] }
end top
namespace linear_map
theorem injective_iff_surjective_of_findim_eq_findim [finite_dimensional K V]
[finite_dimensional K V₂] (H : findim K V = findim K V₂) {f : V →ₗ[K] V₂} :
function.injective f ↔ function.surjective f :=
begin
have := findim_range_add_findim_ker f,
rw [← ker_eq_bot, ← range_eq_top], refine ⟨λ h, _, λ h, _⟩,
{ rw [h, findim_bot, add_zero, H] at this, exact eq_top_of_findim_eq this },
{ rw [h, findim_top, H] at this, exact findim_eq_zero.1 (add_right_injective _ this) }
end
theorem findim_le_findim_of_injective [finite_dimensional K V] [finite_dimensional K V₂]
{f : V →ₗ[K] V₂} (hf : function.injective f) : findim K V ≤ findim K V₂ :=
calc findim K V
= findim K f.range + findim K f.ker : (findim_range_add_findim_ker f).symm
... = findim K f.range : by rw [ker_eq_bot.2 hf, findim_bot, add_zero]
... ≤ findim K V₂ : submodule.findim_le _
end linear_map
namespace alg_hom
lemma bijective {F : Type*} [field F] {E : Type*} [field E] [algebra F E]
[finite_dimensional F E] (ϕ : E →ₐ[F] E) : function.bijective ϕ :=
have inj : function.injective ϕ.to_linear_map := ϕ.to_ring_hom.injective,
⟨inj, (linear_map.injective_iff_surjective_of_findim_eq_findim rfl).mp inj⟩
end alg_hom
/-- Biijection between algebra equivalences and algebra homomorphisms -/
noncomputable def alg_equiv_equiv_alg_hom (F : Type u) [field F] (E : Type v) [field E]
[algebra F E] [finite_dimensional F E] : (E ≃ₐ[F] E) ≃ (E →ₐ[F] E) :=
{ to_fun := λ ϕ, ϕ.to_alg_hom,
inv_fun := λ ϕ, alg_equiv.of_bijective ϕ ϕ.bijective,
left_inv := λ _, by {ext, refl},
right_inv := λ _, by {ext, refl} }
section
/-- An integral domain that is module-finite as an algebra over a field is a field. -/
noncomputable def field_of_finite_dimensional (F K : Type*) [field F] [integral_domain K]
[algebra F K] [finite_dimensional F K] : field K :=
{ inv := λ x, if H : x = 0 then 0 else classical.some $
(show function.surjective (algebra.lmul_left F x), from
linear_map.injective_iff_surjective.1 $ λ _ _, (mul_right_inj' H).1) 1,
mul_inv_cancel := λ x hx, show x * dite _ _ _ = _, by { rw dif_neg hx,
exact classical.some_spec ((show function.surjective (algebra.lmul_left F x), from
linear_map.injective_iff_surjective.1 $ λ _ _, (mul_right_inj' hx).1) 1) },
inv_zero := dif_pos rfl,
.. ‹integral_domain K› }
end
namespace submodule
lemma findim_mono [finite_dimensional K V] :
monotone (λ (s : submodule K V), findim K s) :=
λ s t hst,
calc findim K s = findim K (comap t.subtype s)
: linear_equiv.findim_eq (comap_subtype_equiv_of_le hst).symm
... ≤ findim K t : submodule.findim_le _
lemma lt_of_le_of_findim_lt_findim {s t : submodule K V}
(le : s ≤ t) (lt : findim K s < findim K t) : s < t :=
lt_of_le_of_ne le (λ h, ne_of_lt lt (by rw h))
lemma lt_top_of_findim_lt_findim {s : submodule K V}
(lt : findim K s < findim K V) : s < ⊤ :=
begin
by_cases fin : (finite_dimensional K V),
{ haveI := fin,
rw ← @findim_top K V at lt,
exact lt_of_le_of_findim_lt_findim le_top lt },
{ exfalso,
have : findim K V = 0 := dif_neg (mt finite_dimensional_iff_dim_lt_omega.mpr fin),
rw this at lt,
exact nat.not_lt_zero _ lt }
end
lemma findim_lt_findim_of_lt [finite_dimensional K V] {s t : submodule K V} (hst : s < t) :
findim K s < findim K t :=
begin
rw linear_equiv.findim_eq (comap_subtype_equiv_of_le (le_of_lt hst)).symm,
refine findim_lt (lt_of_le_of_ne le_top _),
intro h_eq_top,
rw comap_subtype_eq_top at h_eq_top,
apply not_le_of_lt hst h_eq_top,
end
end submodule
section span
open submodule
lemma findim_span_le_card (s : set V) [fin : fintype s] :
findim K (span K s) ≤ s.to_finset.card :=
begin
haveI := span_of_finite K ⟨fin⟩,
have : dim K (span K s) ≤ (mk s : cardinal) := dim_span_le s,
rw [←findim_eq_dim, cardinal.fintype_card, ←set.to_finset_card] at this,
exact_mod_cast this
end
lemma findim_span_eq_card {ι : Type*} [fintype ι] {b : ι → V}
(hb : linear_independent K b) :
findim K (span K (set.range b)) = fintype.card ι :=
begin
haveI : finite_dimensional K (span K (set.range b)) := span_of_finite K (set.finite_range b),
have : dim K (span K (set.range b)) = (mk (set.range b) : cardinal) := dim_span hb,
rwa [←findim_eq_dim, ←lift_inj, mk_range_eq_of_injective hb.injective,
cardinal.fintype_card, lift_nat_cast, lift_nat_cast, nat_cast_inj] at this,
end
lemma findim_span_set_eq_card (s : set V) [fin : fintype s]
(hs : linear_independent K (coe : s → V)) :
findim K (span K s) = s.to_finset.card :=
begin
haveI := span_of_finite K ⟨fin⟩,
have : dim K (span K s) = (mk s : cardinal) := dim_span_set hs,
rw [←findim_eq_dim, cardinal.fintype_card, ←set.to_finset_card] at this,
exact_mod_cast this
end
lemma span_lt_of_subset_of_card_lt_findim {s : set V} [fintype s] {t : submodule K V}
(subset : s ⊆ t) (card_lt : s.to_finset.card < findim K t) : span K s < t :=
lt_of_le_of_findim_lt_findim (span_le.mpr subset) (lt_of_le_of_lt (findim_span_le_card _) card_lt)
lemma span_lt_top_of_card_lt_findim {s : set V} [fintype s]
(card_lt : s.to_finset.card < findim K V) : span K s < ⊤ :=
lt_top_of_findim_lt_findim (lt_of_le_of_lt (findim_span_le_card _) card_lt)
end span
section is_basis
lemma linear_independent_of_span_eq_top_of_card_eq_findim {ι : Type*} [fintype ι] {b : ι → V}
(span_eq : span K (set.range b) = ⊤) (card_eq : fintype.card ι = findim K V) :
linear_independent K b :=
linear_independent_iff'.mpr $ λ s g dependent i i_mem_s,
begin
by_contra gx_ne_zero,
-- We'll derive a contradiction by showing `b '' (univ \ {i})` of cardinality `n - 1`
-- spans a vector space of dimension `n`.
refine ne_of_lt (span_lt_top_of_card_lt_findim
(show (b '' (set.univ \ {i})).to_finset.card < findim K V, from _)) _,
{ calc (b '' (set.univ \ {i})).to_finset.card = ((set.univ \ {i}).to_finset.image b).card
: by rw [set.to_finset_card, fintype.card_of_finset]
... ≤ (set.univ \ {i}).to_finset.card : finset.card_image_le
... = (finset.univ.erase i).card : congr_arg finset.card (finset.ext (by simp [and_comm]))
... < finset.univ.card : finset.card_erase_lt_of_mem (finset.mem_univ i)
... = findim K V : card_eq },
-- We already have that `b '' univ` spans the whole space,
-- so we only need to show that the span of `b '' (univ \ {i})` contains each `b j`.
refine trans (le_antisymm (span_mono (set.image_subset_range _ _)) (span_le.mpr _)) span_eq,
rintros _ ⟨j, rfl, rfl⟩,
-- The case that `j ≠ i` is easy because `b j ∈ b '' (univ \ {i})`.
by_cases j_eq : j = i,
swap,
{ refine subset_span ⟨j, (set.mem_diff _).mpr ⟨set.mem_univ _, _⟩, rfl⟩,
exact mt set.mem_singleton_iff.mp j_eq },
-- To show `b i ∈ span (b '' (univ \ {i}))`, we use that it's a weighted sum
-- of the other `b j`s.
rw [j_eq, mem_coe, show b i = -((g i)⁻¹ • (s.erase i).sum (λ j, g j • b j)), from _],
{ refine submodule.neg_mem _ (smul_mem _ _ (sum_mem _ (λ k hk, _))),
obtain ⟨k_ne_i, k_mem⟩ := finset.mem_erase.mp hk,
refine smul_mem _ _ (subset_span ⟨k, _, rfl⟩),
simpa using k_mem },
-- To show `b i` is a weighted sum of the other `b j`s, we'll rewrite this sum
-- to have the form of the assumption `dependent`.
apply eq_neg_of_add_eq_zero,
calc b i + (g i)⁻¹ • (s.erase i).sum (λ j, g j • b j)
= (g i)⁻¹ • (g i • b i + (s.erase i).sum (λ j, g j • b j))
: by rw [smul_add, ←mul_smul, inv_mul_cancel gx_ne_zero, one_smul]
... = (g i)⁻¹ • 0 : congr_arg _ _
... = 0 : smul_zero _,
-- And then it's just a bit of manipulation with finite sums.
rwa [← finset.insert_erase i_mem_s, finset.sum_insert (finset.not_mem_erase _ _)] at dependent
end
/-- A finite family of vectors is linearly independent if and only if
its cardinality equals the dimension of its span. -/
lemma linear_independent_iff_card_eq_findim_span {ι : Type*} [fintype ι] {b : ι → V} :
linear_independent K b ↔ fintype.card ι = findim K (span K (set.range b)) :=
begin
split,
{ intro h,
exact (findim_span_eq_card h).symm },
{ intro hc,
let f := (submodule.subtype (span K (set.range b))),
let b' : ι → span K (set.range b) :=
λ i, ⟨b i, mem_span.2 (λ p hp, hp (set.mem_range_self _))⟩,
have hs : span K (set.range b') = ⊤,
{ rw eq_top_iff',
intro x,
have h : span K (f '' (set.range b')) = map f (span K (set.range b')) := span_image f,
have hf : f '' (set.range b') = set.range b, { ext x, simp [set.mem_image, set.mem_range] },
rw hf at h,
have hx : (x : V) ∈ span K (set.range b) := x.property,
conv at hx { congr, skip, rw h },
simpa [mem_map] using hx },
have hi : f.ker = ⊥ := ker_subtype _,
convert (linear_independent_of_span_eq_top_of_card_eq_findim hs hc).map' _ hi }
end
lemma is_basis_of_span_eq_top_of_card_eq_findim {ι : Type*} [fintype ι] {b : ι → V}
(span_eq : span K (set.range b) = ⊤) (card_eq : fintype.card ι = findim K V) :
is_basis K b :=
⟨linear_independent_of_span_eq_top_of_card_eq_findim span_eq card_eq, span_eq⟩
lemma finset_is_basis_of_span_eq_top_of_card_eq_findim {s : finset V}
(span_eq : span K (↑s : set V) = ⊤) (card_eq : s.card = findim K V) :
is_basis K (coe : (↑s : set V) → V) :=
is_basis_of_span_eq_top_of_card_eq_findim
((@subtype.range_coe_subtype _ (λ x, x ∈ s)).symm ▸ span_eq)
(trans (fintype.card_coe _) card_eq)
lemma set_is_basis_of_span_eq_top_of_card_eq_findim {s : set V} [fintype s]
(span_eq : span K s = ⊤) (card_eq : s.to_finset.card = findim K V) :
is_basis K (λ (x : s), (x : V)) :=
is_basis_of_span_eq_top_of_card_eq_findim
((@subtype.range_coe_subtype _ s).symm ▸ span_eq)
(trans s.to_finset_card.symm card_eq)
lemma span_eq_top_of_linear_independent_of_card_eq_findim
{ι : Type*} [hι : nonempty ι] [fintype ι] {b : ι → V}
(lin_ind : linear_independent K b) (card_eq : fintype.card ι = findim K V) :
span K (set.range b) = ⊤ :=
begin
by_cases fin : (finite_dimensional K V),
{ haveI := fin,
by_contra ne_top,
have lt_top : span K (set.range b) < ⊤ := lt_of_le_of_ne le_top ne_top,
exact ne_of_lt (submodule.findim_lt lt_top) (trans (findim_span_eq_card lin_ind) card_eq) },
{ exfalso,
apply ne_of_lt (fintype.card_pos_iff.mpr hι),
symmetry,
calc fintype.card ι = findim K V : card_eq
... = 0 : dif_neg (mt finite_dimensional_iff_dim_lt_omega.mpr fin) }
end
lemma is_basis_of_linear_independent_of_card_eq_findim
{ι : Type*} [nonempty ι] [fintype ι] {b : ι → V}
(lin_ind : linear_independent K b) (card_eq : fintype.card ι = findim K V) :
is_basis K b :=
⟨lin_ind, span_eq_top_of_linear_independent_of_card_eq_findim lin_ind card_eq⟩
lemma finset_is_basis_of_linear_independent_of_card_eq_findim
{s : finset V} (hs : s.nonempty)
(lin_ind : linear_independent K (coe : (↑s : set V) → V)) (card_eq : s.card = findim K V) :
is_basis K (coe : (↑s : set V) → V) :=
@is_basis_of_linear_independent_of_card_eq_findim _ _ _ _ _ _
⟨(⟨hs.some, hs.some_spec⟩ : (↑s : set V))⟩ _ _
lin_ind
(trans (fintype.card_coe _) card_eq)
lemma set_is_basis_of_linear_independent_of_card_eq_findim
{s : set V} [nonempty s] [fintype s]
(lin_ind : linear_independent K (coe : s → V)) (card_eq : s.to_finset.card = findim K V) :
is_basis K (coe : s → V) :=
is_basis_of_linear_independent_of_card_eq_findim lin_ind (trans s.to_finset_card.symm card_eq)
end is_basis
section subalgebra_dim
open vector_space
variables {F E : Type*} [field F] [field E] [algebra F E]
lemma subalgebra.dim_eq_one_of_eq_bot {S : subalgebra F E} (h : S = ⊥) : dim F S = 1 :=
begin
rw [← S.to_submodule_equiv.dim_eq, h,
(linear_equiv.of_eq ↑(⊥ : subalgebra F E) _ algebra.to_submodule_bot).dim_eq, dim_span_set],
exacts [mk_singleton _, linear_independent_singleton one_ne_zero]
end
@[simp]
lemma subalgebra.dim_bot : dim F (⊥ : subalgebra F E) = 1 :=
subalgebra.dim_eq_one_of_eq_bot rfl
lemma subalgebra_top_dim_eq_submodule_top_dim :
dim F (⊤ : subalgebra F E) = dim F (⊤ : submodule F E) :=
by { rw ← algebra.coe_top, refl }
lemma subalgebra_top_findim_eq_submodule_top_findim :
findim F (⊤ : subalgebra F E) = findim F (⊤ : submodule F E) :=
by { rw ← algebra.coe_top, refl }
lemma subalgebra.dim_top : dim F (⊤ : subalgebra F E) = dim F E :=
by { rw subalgebra_top_dim_eq_submodule_top_dim, exact dim_top }
lemma subalgebra.finite_dimensional_bot : finite_dimensional F (⊥ : subalgebra F E) :=
finite_dimensional_of_dim_eq_one subalgebra.dim_bot
@[simp]
lemma subalgebra.findim_bot : findim F (⊥ : subalgebra F E) = 1 :=
begin
haveI : finite_dimensional F (⊥ : subalgebra F E) := subalgebra.finite_dimensional_bot,
have : dim F (⊥ : subalgebra F E) = 1 := subalgebra.dim_bot,
rw ← findim_eq_dim at this,
norm_cast at *,
simp *,
end
lemma subalgebra.findim_eq_one_of_eq_bot {S : subalgebra F E} (h : S = ⊥) : findim F S = 1 :=
by { rw h, exact subalgebra.findim_bot }
lemma subalgebra.eq_bot_of_findim_one {S : subalgebra F E} (h : findim F S = 1) : S = ⊥ :=
begin
rw eq_bot_iff,
let b : set S := {1},
have : fintype b := unique.fintype,
have b_lin_ind : linear_independent F (coe : b → S) := linear_independent_singleton one_ne_zero,
have b_card : fintype.card b = 1 := fintype.card_of_subsingleton _,
obtain ⟨_, b_spans⟩ := set_is_basis_of_linear_independent_of_card_eq_findim
b_lin_ind (by simp only [*, set.to_finset_card]),
intros x hx,
rw [subalgebra.mem_coe, algebra.mem_bot],
have x_in_span_b : (⟨x, hx⟩ : S) ∈ submodule.span F b,
{ rw subtype.range_coe at b_spans,
rw b_spans,
exact submodule.mem_top, },
obtain ⟨a, ha⟩ := submodule.mem_span_singleton.mp x_in_span_b,
replace ha : a • 1 = x := by injections with ha,
exact ⟨a, by rw [← ha, algebra.smul_def, mul_one]⟩,
end
lemma subalgebra.eq_bot_of_dim_one {S : subalgebra F E} (h : dim F S = 1) : S = ⊥ :=
begin
haveI : finite_dimensional F S := finite_dimensional_of_dim_eq_one h,
rw ← findim_eq_dim at h,
norm_cast at h,
exact subalgebra.eq_bot_of_findim_one h,
end
@[simp]
lemma subalgebra.bot_eq_top_of_dim_eq_one (h : dim F E = 1) : (⊥ : subalgebra F E) = ⊤ :=
begin
rw [← dim_top, ← subalgebra_top_dim_eq_submodule_top_dim] at h,
exact eq.symm (subalgebra.eq_bot_of_dim_one h),
end
@[simp]
lemma subalgebra.bot_eq_top_of_findim_eq_one (h : findim F E = 1) : (⊥ : subalgebra F E) = ⊤ :=
begin
rw [← findim_top, ← subalgebra_top_findim_eq_submodule_top_findim] at h,
exact eq.symm (subalgebra.eq_bot_of_findim_one h),
end
@[simp]
theorem subalgebra.dim_eq_one_iff {S : subalgebra F E} : dim F S = 1 ↔ S = ⊥ :=
⟨subalgebra.eq_bot_of_dim_one, subalgebra.dim_eq_one_of_eq_bot⟩
@[simp]
theorem subalgebra.findim_eq_one_iff {S : subalgebra F E} : findim F S = 1 ↔ S = ⊥ :=
⟨subalgebra.eq_bot_of_findim_one, subalgebra.findim_eq_one_of_eq_bot⟩
end subalgebra_dim
namespace module
namespace End
lemma exists_ker_pow_eq_ker_pow_succ [finite_dimensional K V] (f : End K V) :
∃ (k : ℕ), k ≤ findim K V ∧ (f ^ k).ker = (f ^ k.succ).ker :=
begin
classical,
by_contradiction h_contra,
simp_rw [not_exists, not_and] at h_contra,
have h_le_ker_pow : ∀ (n : ℕ), n ≤ (findim K V).succ → n ≤ findim K (f ^ n).ker,
{ intros n hn,
induction n with n ih,
{ exact zero_le (findim _ _) },
{ have h_ker_lt_ker : (f ^ n).ker < (f ^ n.succ).ker,
{ refine lt_of_le_of_ne _ (h_contra n (nat.le_of_succ_le_succ hn)),
rw pow_succ,
apply linear_map.ker_le_ker_comp },
have h_findim_lt_findim : findim K (f ^ n).ker < findim K (f ^ n.succ).ker,
{ apply submodule.findim_lt_findim_of_lt h_ker_lt_ker },
calc
n.succ ≤ (findim K ↥(linear_map.ker (f ^ n))).succ :
nat.succ_le_succ (ih (nat.le_of_succ_le hn))
... ≤ findim K ↥(linear_map.ker (f ^ n.succ)) :
nat.succ_le_of_lt h_findim_lt_findim } },
have h_le_findim_V : ∀ n, findim K (f ^ n).ker ≤ findim K V :=
λ n, submodule.findim_le _,
have h_any_n_lt: ∀ n, n ≤ (findim K V).succ → n ≤ findim K V :=
λ n hn, (h_le_ker_pow n hn).trans (h_le_findim_V n),
show false,
from nat.not_succ_le_self _ (h_any_n_lt (findim K V).succ (findim K V).succ.le_refl),
end
lemma ker_pow_constant {f : End K V} {k : ℕ} (h : (f ^ k).ker = (f ^ k.succ).ker) :
∀ m, (f ^ k).ker = (f ^ (k + m)).ker
| 0 := by simp
| (m + 1) :=
begin
apply le_antisymm,
{ rw [add_comm, pow_add],
apply linear_map.ker_le_ker_comp },
{ rw [ker_pow_constant m, add_comm m 1, ←add_assoc, pow_add, pow_add f k m],
change linear_map.ker ((f ^ (k + 1)).comp (f ^ m)) ≤ linear_map.ker ((f ^ k).comp (f ^ m)),
rw [linear_map.ker_comp, linear_map.ker_comp, h, nat.add_one],
exact le_refl _, }
end
lemma ker_pow_eq_ker_pow_findim_of_le [finite_dimensional K V]
{f : End K V} {m : ℕ} (hm : findim K V ≤ m) :
(f ^ m).ker = (f ^ findim K V).ker :=
begin
obtain ⟨k, h_k_le, hk⟩ :
∃ k, k ≤ findim K V ∧ linear_map.ker (f ^ k) = linear_map.ker (f ^ k.succ) :=
exists_ker_pow_eq_ker_pow_succ f,
calc (f ^ m).ker = (f ^ (k + (m - k))).ker :
by rw nat.add_sub_of_le (h_k_le.trans hm)
... = (f ^ k).ker : by rw ker_pow_constant hk _
... = (f ^ (k + (findim K V - k))).ker : ker_pow_constant hk (findim K V - k)
... = (f ^ findim K V).ker : by rw nat.add_sub_of_le h_k_le
end
lemma ker_pow_le_ker_pow_findim [finite_dimensional K V] (f : End K V) (m : ℕ) :
(f ^ m).ker ≤ (f ^ findim K V).ker :=
begin
by_cases h_cases: m < findim K V,
{ rw [←nat.add_sub_of_le (nat.le_of_lt h_cases), add_comm, pow_add],
apply linear_map.ker_le_ker_comp },
{ rw [ker_pow_eq_ker_pow_findim_of_le (le_of_not_lt h_cases)],
exact le_refl _ }
end
end End
end module
|
e211119d2f048a2ec996eee5e110c398719eeaef | 3bdd27ffdff3ffa22d4bb010eba695afcc96bc4a | /src/combinatorics/simplicial_complex/link.lean | 01f7f1ad074f503729a24f6ed7a18e6d3df7f26a | [] | no_license | mmasdeu/brouwerfixedpoint | 684d712c982c6a8b258b4e2c6b2eab923f2f1289 | 548270f79ecf12d7e20a256806ccb9fcf57b87e2 | refs/heads/main | 1,690,539,793,996 | 1,631,801,831,000 | 1,631,801,831,000 | 368,139,809 | 4 | 3 | null | 1,624,453,250,000 | 1,621,246,034,000 | Lean | UTF-8 | Lean | false | false | 6,763 | lean | /-
Copyright (c) 2021 Yaël Dillies, Bhavik Mehta. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies, Bhavik Mehta
-/
import combinatorics.simplicial_complex.closure
import combinatorics.simplicial_complex.star
namespace affine
open set
variables {m n k : ℕ} {E : Type*} [normed_group E] [normed_space ℝ E]
{S : simplicial_complex E} {X Y : finset E} {A : set (finset E)}
[semilattice_inf_bot (finset E)] [decidable_eq E]
def simplicial_complex.link (S : simplicial_complex E) (A : set (finset E)) :
simplicial_complex E :=
{ faces := {X | (∀ {W}, W ∈ A → disjoint W X) ∧ ∃ {Y Z}, Y ∈ A ∧ Z ∈ S.faces ∧ X ⊆ Z ∧ Y ⊆ Z},
indep := λ X ⟨hXdisj, Y, Z, hY, hZ, hXZ, hYZ⟩, S.indep (S.down_closed hZ hXZ),
down_closed := begin
rintro X W ⟨hXdisj, Y, Z, hY, hZ, hXZ, hYZ⟩ hWX,
split,
{ rintro V hV,
-- exact finset.disjoint_of_subset_right hWX (hXdisj hV),
sorry
},
{ exact ⟨Y, Z, hY, hZ, subset.trans hWX hXZ, hYZ⟩ }
end,
disjoint := λ X X' ⟨hXdisj, Y, Z, hY, hZ, hXZ, hYZ⟩ ⟨hXdisj', Y', Z', hY', hZ', hXZ', hYZ'⟩,
S.disjoint (S.down_closed hZ hXZ) (S.down_closed hZ' hXZ') }
lemma link_empty :
(S.link ∅).faces = ∅ :=
begin
unfold simplicial_complex.link,
simp,
end
lemma link_singleton_empty :
S.link {∅} = S :=
begin
/-
ext X,
split,
{
rintro ⟨_, _, Z, _, hZ, hXZ, _⟩,
exact S.down_closed hZ hXZ,
},
{
rintro hX,
split,
{ rintro W (h : W = ∅),
rw h,
exact finset.disjoint_empty_left X, },
exact ⟨∅, X, rfl, hX, subset.refl X, empty_subset X⟩,
}
-/
sorry
end
lemma mem_link_singleton_iff :
Y ∈ (S.link {X}).faces ↔ disjoint X Y ∧ ∃ {Z}, Z ∈ S.faces ∧ Y ⊆ Z ∧ X ⊆ Z :=
begin
unfold simplicial_complex.link,
simp,
end
lemma link_singleton_subset (hX : X ≠ ∅) :
(S.link {X}).faces ⊆ (S.Star {X}).faces \ S.star {X} :=
begin
rintro Y ⟨hY, W, Z, (hWX : W = X), hZ, hYZ, hWZ⟩,
simp at hY,
subst hWX,
split,
{ exact ⟨W, Z, mem_singleton W, hZ, hYZ, hWZ⟩, },
{ rintro h,
rw mem_star_singleton_iff at h,
--exact hX (disjoint_self.1 (finset.disjoint_of_subset_right h.2 hY)), }
sorry
}
end
lemma link_singleton_eq_Star_minus_star_iff_singleton (hX : X ≠ ∅) :
(S.link {X}).faces = (S.Star {X}).faces \ S.star {X} ↔ X.card = 1 :=
begin
split,
{
sorry --true? The PDF claims so but I'm not sure
},
{
sorry
/-
rintro hXcard,
apply subset.antisymm (link_singleton_subset hX),
rintro Y ⟨h, hYstar⟩,
obtain ⟨Z, hZ, hYZ, hXZ⟩ := mem_Star_singleton_iff.1 h,
split,
{
obtain ⟨x, hxX⟩ := finset.card_eq_one.1 hXcard,
rintro W (hW : W = X),
subst hW,
subst hxX,
rw finset.singleton_disjoint,
rintro hx,
apply hYstar,
rw [mem_star_singleton_iff, finset.singleton_subset_iff],
exact ⟨S.down_closed hZ hYZ, hx⟩,
},
exact ⟨X, Z, rfl, hZ, hYZ, hXZ⟩,
-/
}
end
lemma link_subset :
(S.link A).faces ⊆ S.faces :=
λ X ⟨hXdisj, Y, Z, hY, hZ, hXZ, hYZ⟩, S.down_closed hZ hXZ
lemma link_eq_Star_sub_star_closure {S : simplicial_complex E} {A : set (finset E)} :
(S.link A).faces = (S.Star A).faces \ S.star ((S.closure A).faces \ {∅}) :=
begin
/-
ext X,
split,
{
rintro ⟨hXdisj, hXStar⟩,
use hXStar,
rintro ⟨hX, Y, ⟨⟨hY, Z, hZ, hYZ⟩, (hYnonempty : Y ≠ ∅)⟩, hYX⟩,
have hYZX : Y ⊆ Z ∩ X := finset.subset_inter hYZ hYX,
rw finset.disjoint_iff_inter_eq_empty.mp (hXdisj hZ) at hYZX,
exact hYnonempty (finset.subset_empty.mp hYZX),
},
{
rintro ⟨hXStar, hX'⟩,
split,
{
rintro W hW,
rw finset.disjoint_iff_inter_eq_empty,
apply finset.eq_empty_of_forall_not_mem,
rintro x hx,
apply hX',
use Star_subset hXStar,
use {x},
split,
split,
{
unfold simplicial_complex.closure simplicial_complex.of_surcomplex,
simp,
exact ⟨S.down_closed (Star_subset hXStar) (subset.trans (finset.singleton_subset_iff.2 hx)
(finset.inter_subset_right _ _)), W, hW, finset.inter_subset_left _ _ hx⟩,
},
rintro (h : {x} = ∅),
exact (finset.singleton_ne_empty x) h,
exact finset.singleton_subset_iff.2 (finset.inter_subset_right W X hx),
},
{ exact hXStar }
}
-/
sorry
end
/-
lemma link_facet_iff {S : simplicial_complex E} {A : set (finset E)} {n k : ℕ}
(hS : S.pure_of n) {X : finset E} (hA : ∀ {W}, W ∈ A → (W : finset _).card = k) :
X ∈ (S.link A).facets ↔ ∃ {W Y}, W ∈ A ∧ Y ∈ S.facets ∧ W ⊆ Y ∧ X = Y \ W :=-/
-- X ∈ (S.link A).facets ↔ X ∉ S.facets ∧ (∀ {W}, W ∈ A → disjoint W X) ∧ ∃ {Y W Z}, Y ∈ S.facets ∧
-- W ∈ A ∧ Z ∈ S.facets ∧ X ∪ W ⊆ Z ∧ ∀ {y}, y ∈ Y → y ∈ X ∨ ∃ {V}, V ∈ A ∧ y ∈ V
lemma link_facet_iff :
X ∈ (S.link A).facets ↔ X ∉ S.facets ∧ (∀ {W}, W ∈ A → disjoint W X) ∧ ∃ {W Y Z},
W ∈ A ∧ Y ∈ S.facets ∧ Z ∈ S.faces ∧ X ∪ W ⊆ Z ∧ ∀ {y}, y ∈ Y → y ∈ X ∨ ∃ {V}, V ∈ A ∧ y ∈ V :=
begin
split,
{
rintro ⟨⟨hXdisj, W, Z, hW, hZ, hXZ, hWZ⟩, hXmax⟩,
sorry
/-obtain ⟨Y, hY, hZY⟩ := subfacet hZ,
split,
{
sorry
},
{
use [(λ W, hXdisj), W, Y, Z, hW, hY, hZ, finset.union_subset hXZ hWZ],
rintro y hy,
sorry
}-/
},
{
rintro ⟨stuff, hXdisj, W, Y, Z, hW, hY, hZ, hXYW, hunion⟩,
split,
{
have hXZ : X ⊆ Z := sorry, -- finset.union_subset_iff.1 hXYW
have hWZ : W ⊆ Z := sorry, -- finset.union_subset_iff.1 hXYW
exact ⟨(λ V, hXdisj), W, Z, hW, hZ, hXZ, hWZ⟩,
},
{
rintro V ⟨hVdisj, U, R, hU, hR, hVR, hUR⟩ hXV,
apply finset.subset.antisymm hXV,
rintro v hv,
/-have := hA hU hW (facets_subset hY) hWY,
rw finset.mem_sdiff,-/
--have := hA hV hW (facets_subset hY) hWY ⟨x, finset.mem_inter.2 ⟨hx.1, hx.2.1⟩⟩,
sorry
/-apply finset.eq_of_subset_of_card_le hYWX,
rw finset.card_sdiff hWY,
have := finset.card_le_of_subset (finset.union_subset hUV hXV),
rw [finset.card_disjoint_union (hXdisj hU), hA hU] at this,
rw [hA hW, hS hY],
exact nat.le_sub_left_of_add_le (le_trans this (face_card_le_pureness hS hV)),-/
}
}
end
lemma pure_link_of_pure (hS : S.pure_of n) (hA : ∀ {X}, X ∈ A → (X : finset _).card = k) :
(S.link A).pure_of (n - k) :=
begin
rintro X ⟨⟨hXdisj, W, Z, hW, hZ, hXZ, hWZ⟩, hXmax⟩, --easy once we have `link_facet_iff`
sorry
end
end affine
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