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3a2fff59f2f73d34d7152a27332b67c9a3469fb1 | f5f7e6fae601a5fe3cac7cc3ed353ed781d62419 | /src/analysis/normed_space/bounded_linear_maps.lean | 98b49ea84bc43a2065b61564549b7490b4de6409 | [
"Apache-2.0"
] | permissive | EdAyers/mathlib | 9ecfb2f14bd6caad748b64c9c131befbff0fb4e0 | ca5d4c1f16f9c451cf7170b10105d0051db79e1b | refs/heads/master | 1,626,189,395,845 | 1,555,284,396,000 | 1,555,284,396,000 | 144,004,030 | 0 | 0 | Apache-2.0 | 1,533,727,664,000 | 1,533,727,663,000 | null | UTF-8 | Lean | false | false | 6,917 | 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 algebra.field
import tactic.norm_num
import analysis.normed_space.basic
import analysis.asymptotics
@[simp] lemma mul_inv_eq' {α} [discrete_field α] (a b : α) : (a * b)⁻¹ = b⁻¹ * a⁻¹ :=
classical.by_cases (assume : a = 0, by simp [this]) $ assume ha,
classical.by_cases (assume : b = 0, by simp [this]) $ assume hb,
mul_inv_eq hb ha
noncomputable theory
local attribute [instance] classical.prop_decidable
local notation f ` →_{`:50 a `} `:0 b := filter.tendsto f (nhds a) (nhds b)
open filter (tendsto)
open metric
variables {k : Type*} [normed_field k]
variables {E : Type*} [normed_space k E]
variables {F : Type*} [normed_space k F]
variables {G : Type*} [normed_space k G]
structure is_bounded_linear_map (k : Type*)
[normed_field k] {E : Type*} [normed_space k E] {F : Type*} [normed_space k F] (L : E → F)
extends is_linear_map k L : Prop :=
(bound : ∃ M, M > 0 ∧ ∀ x : E, ∥ L x ∥ ≤ M * ∥ x ∥)
include k
lemma is_linear_map.with_bound
{L : E → F} (hf : is_linear_map k L) (M : ℝ) (h : ∀ x : E, ∥ L x ∥ ≤ M * ∥ x ∥) :
is_bounded_linear_map k L :=
⟨ 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⟩)⟩
namespace is_bounded_linear_map
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)
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]
set_option class.instance_max_depth 43
lemma smul {f : E → F} (c : k) : is_bounded_linear_map k f → is_bounded_linear_map k (λ e, c • f e)
| ⟨hf, ⟨M, hM, h⟩⟩ := (c • hf.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 (h x) (norm_nonneg c)
... = (∥c∥ * M) * ∥x∥ : (mul_assoc _ _ _).symm
lemma neg {f : E → F} (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 {f : E → F} {g : E → F} :
is_bounded_linear_map k f → is_bounded_linear_map k g → is_bounded_linear_map k (λ e, f e + g e)
| ⟨hlf, Mf, hMf, hf⟩ ⟨hlg, Mg, hMg, hg⟩ := (hlf.mk' _ + hlg.mk' _).is_linear.with_bound (Mf + Mg) $ assume x,
calc ∥f x + g x∥ ≤ ∥f x∥ + ∥g x∥ : norm_triangle _ _
... ≤ Mf * ∥x∥ + Mg * ∥x∥ : add_le_add (hf x) (hg x)
... ≤ (Mf + Mg) * ∥x∥ : by rw add_mul
lemma sub {f : E → F} {g : E → F} (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) := add hf (neg hg)
lemma comp {f : E → F} {g : F → G} :
is_bounded_linear_map k g → is_bounded_linear_map k f → is_bounded_linear_map k (g ∘ f)
| ⟨hlg, Mg, hMg, hg⟩ ⟨hlf, Mf, hMf, hf⟩ := ((hlg.mk' _).comp (hlf.mk' _)).is_linear.with_bound (Mg * Mf) $ assume x,
calc ∥g (f x)∥ ≤ Mg * ∥f x∥ : hg _
... ≤ Mg * (Mf * ∥x∥) : mul_le_mul_of_nonneg_left (hf _) (le_of_lt hMg)
... = Mg * Mf * ∥x∥ : (mul_assoc _ _ _).symm
lemma tendsto {L : E → F} (x : E) : is_bounded_linear_map k L → L →_{x} (L x)
| ⟨hL, M, hM, h_ineq⟩ := tendsto_iff_norm_tendsto_zero.2 $
squeeze_zero (assume e, norm_nonneg _)
(assume e, calc ∥L e - L x∥ = ∥hL.mk' L (e - x)∥ : by rw (hL.mk' _).map_sub e x; refl
... ≤ M*∥e-x∥ : h_ineq (e-x))
(suffices (λ (e : E), M * ∥e - x∥) →_{x} (M * 0), by simpa,
tendsto_mul tendsto_const_nhds (lim_norm _))
lemma continuous {L : E → F} (hL : is_bounded_linear_map k L) : continuous L :=
continuous_iff_continuous_at.2 $ assume x, hL.tendsto x
lemma lim_zero_bounded_linear_map {L : E → F} (H : is_bounded_linear_map k L) : (L →_{0} 0) :=
(H.1.mk' _).map_zero ▸ continuous_iff_continuous_at.1 H.continuous 0
section
open asymptotics filter
theorem is_O_id {L : E → F} (h : is_bounded_linear_map k L) (l : filter E) :
is_O L (λ x, x) l :=
let ⟨M, Mpos, hM⟩ := h.bound in
⟨M, Mpos, mem_sets_of_superset univ_mem_sets (λ x _, hM x)⟩
theorem is_O_comp {L : F → G} (h : is_bounded_linear_map k L)
{f : E → F} (l : filter E) : is_O (λ x', L (f x')) f l :=
((h.is_O_id ⊤).comp _).mono (map_le_iff_le_comap.mp lattice.le_top)
theorem is_O_sub {L : E → F} (h : is_bounded_linear_map k L) (l : filter E) (x : E) :
is_O (λ x', L (x' - x)) (λ x', x' - x) l :=
is_O_comp h l
end
end is_bounded_linear_map
set_option class.instance_max_depth 60
/-- A continuous linear map between normed spaces is bounded when the field is nondiscrete.
The continuity ensures boundedness on a ball of some radius δ. The nondiscreteness is then
used to rescale any element into an element of norm in [δ/C, δ], whose image has a controlled norm.
The norm control for the original element follows by rescaling. -/
theorem is_linear_map.bounded_of_continuous_at {k : Type*} [nondiscrete_normed_field k]
{E : Type*} [normed_space k E] {F : Type*} [normed_space k F] {L : E → F} {x₀ : E}
(lin : is_linear_map k L) (cont : continuous_at L x₀) : is_bounded_linear_map k L :=
begin
rcases tendsto_nhds_nhds.1 cont 1 zero_lt_one with ⟨ε, ε_pos, hε⟩,
let δ := ε/2,
have δ_pos : δ > 0 := half_pos ε_pos,
have H : ∀{a}, ∥a∥ ≤ δ → ∥L a∥ ≤ 1,
{ assume a ha,
have : dist (L (x₀+a)) (L x₀) ≤ 1,
{ apply le_of_lt (hε _),
have : dist x₀ (x₀ + a) = ∥a∥, by { rw dist_eq_norm, simp },
rw [dist_comm, this],
exact lt_of_le_of_lt ha (half_lt_self ε_pos) },
simpa [dist_eq_norm, lin.add] using this },
rcases exists_one_lt_norm k with ⟨c, hc⟩,
refine lin.with_bound (δ⁻¹ * ∥c∥) (λx, _),
by_cases h : x = 0,
{ simp only [h, lin.map_zero, norm_zero, mul_zero] },
{ rcases rescale_to_shell hc δ_pos h with ⟨d, hd, dxle, ledx, dinv⟩,
calc ∥L x∥
= ∥L ((d⁻¹ * d) • x)∥ : by rwa [inv_mul_cancel, one_smul]
... = ∥d∥⁻¹ * ∥L (d • x)∥ :
by rw [mul_smul, lin.smul, norm_smul, norm_inv]
... ≤ ∥d∥⁻¹ * 1 :
mul_le_mul_of_nonneg_left (H dxle) (by { rw ← norm_inv, exact norm_nonneg _ })
... ≤ δ⁻¹ * ∥c∥ * ∥x∥ : by { rw mul_one, exact dinv } }
end
|
e2e3b00b70d387ba1f842d40d1ca5f5a29abfbe6 | 626e312b5c1cb2d88fca108f5933076012633192 | /src/algebra/category/Module/monoidal.lean | 1ea5c13e4fbdb473c823c38c98ffd1058437715c | [
"Apache-2.0"
] | permissive | Bioye97/mathlib | 9db2f9ee54418d29dd06996279ba9dc874fd6beb | 782a20a27ee83b523f801ff34efb1a9557085019 | refs/heads/master | 1,690,305,956,488 | 1,631,067,774,000 | 1,631,067,774,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 9,011 | lean | /-
Copyright (c) 2020 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kevin Buzzard, Scott Morrison
-/
import category_theory.monoidal.braided
import algebra.category.Module.basic
import linear_algebra.tensor_product
/-!
# The symmetric monoidal category structure on R-modules
Mostly this uses existing machinery in `linear_algebra.tensor_product`.
We just need to provide a few small missing pieces to build the
`monoidal_category` instance and then the `symmetric_category` instance.
If you're happy using the bundled `Module R`, it may be possible to mostly
use this as an interface and not need to interact much with the implementation details.
-/
universes u
open category_theory
namespace Module
variables {R : Type u} [comm_ring R]
namespace monoidal_category
-- The definitions inside this namespace are essentially private.
-- After we build the `monoidal_category (Module R)` instance,
-- you should use that API.
open_locale tensor_product
local attribute [ext] tensor_product.ext
/-- (implementation) tensor product of R-modules -/
def tensor_obj (M N : Module R) : Module R := Module.of R (M ⊗[R] N)
/-- (implementation) tensor product of morphisms R-modules -/
def tensor_hom {M N M' N' : Module R} (f : M ⟶ N) (g : M' ⟶ N') :
tensor_obj M M' ⟶ tensor_obj N N' :=
tensor_product.map f g
lemma tensor_id (M N : Module R) : tensor_hom (𝟙 M) (𝟙 N) = 𝟙 (Module.of R (↥M ⊗ ↥N)) :=
by tidy
lemma tensor_comp {X₁ Y₁ Z₁ X₂ Y₂ Z₂ : Module R}
(f₁ : X₁ ⟶ Y₁) (f₂ : X₂ ⟶ Y₂) (g₁ : Y₁ ⟶ Z₁) (g₂ : Y₂ ⟶ Z₂) :
tensor_hom (f₁ ≫ g₁) (f₂ ≫ g₂) = tensor_hom f₁ f₂ ≫ tensor_hom g₁ g₂ :=
by tidy
/-- (implementation) the associator for R-modules -/
def associator (M N K : Module R) : tensor_obj (tensor_obj M N) K ≅ tensor_obj M (tensor_obj N K) :=
linear_equiv.to_Module_iso (tensor_product.assoc R M N K)
section
/-! The `associator_naturality` and `pentagon` lemmas below are very slow to elaborate.
We give them some help by expressing the lemmas first non-categorically, then using
`convert _aux using 1` to have the elaborator work as little as possible. -/
open tensor_product (assoc map)
private lemma associator_naturality_aux
{X₁ X₂ X₃ : Type*}
[add_comm_monoid X₁] [add_comm_monoid X₂] [add_comm_monoid X₃]
[module R X₁] [module R X₂] [module R X₃]
{Y₁ Y₂ Y₃ : Type*}
[add_comm_monoid Y₁] [add_comm_monoid Y₂] [add_comm_monoid Y₃]
[module R Y₁] [module R Y₂] [module R Y₃]
(f₁ : X₁ →ₗ[R] Y₁) (f₂ : X₂ →ₗ[R] Y₂) (f₃ : X₃ →ₗ[R] Y₃) :
(↑(assoc R Y₁ Y₂ Y₃) ∘ₗ (map (map f₁ f₂) f₃)) = ((map f₁ (map f₂ f₃)) ∘ₗ ↑(assoc R X₁ X₂ X₃)) :=
begin
apply tensor_product.ext_threefold,
intros x y z,
refl
end
variables (R)
private lemma pentagon_aux
(W X Y Z : Type*)
[add_comm_monoid W] [add_comm_monoid X] [add_comm_monoid Y] [add_comm_monoid Z]
[module R W] [module R X] [module R Y] [module R Z] :
((map (1 : W →ₗ[R] W) (assoc R X Y Z).to_linear_map).comp (assoc R W (X ⊗[R] Y) Z).to_linear_map)
.comp (map ↑(assoc R W X Y) (1 : Z →ₗ[R] Z)) =
(assoc R W X (Y ⊗[R] Z)).to_linear_map.comp (assoc R (W ⊗[R] X) Y Z).to_linear_map :=
begin
apply tensor_product.ext_fourfold,
intros w x y z,
refl
end
end
lemma associator_naturality {X₁ X₂ X₃ Y₁ Y₂ Y₃ : Module R}
(f₁ : X₁ ⟶ Y₁) (f₂ : X₂ ⟶ Y₂) (f₃ : X₃ ⟶ Y₃) :
tensor_hom (tensor_hom f₁ f₂) f₃ ≫ (associator Y₁ Y₂ Y₃).hom =
(associator X₁ X₂ X₃).hom ≫ tensor_hom f₁ (tensor_hom f₂ f₃) :=
by convert associator_naturality_aux f₁ f₂ f₃ using 1
lemma pentagon (W X Y Z : Module R) :
tensor_hom (associator W X Y).hom (𝟙 Z) ≫ (associator W (tensor_obj X Y) Z).hom
≫ tensor_hom (𝟙 W) (associator X Y Z).hom =
(associator (tensor_obj W X) Y Z).hom ≫ (associator W X (tensor_obj Y Z)).hom :=
by convert pentagon_aux R W X Y Z using 1
/-- (implementation) the left unitor for R-modules -/
def left_unitor (M : Module.{u} R) : Module.of R (R ⊗[R] M) ≅ M :=
(linear_equiv.to_Module_iso (tensor_product.lid R M) : of R (R ⊗ M) ≅ of R M).trans (of_self_iso M)
lemma left_unitor_naturality {M N : Module R} (f : M ⟶ N) :
tensor_hom (𝟙 (Module.of R R)) f ≫ (left_unitor N).hom = (left_unitor M).hom ≫ f :=
begin
ext x y, simp,
erw [tensor_product.lid_tmul, tensor_product.lid_tmul],
rw linear_map.map_smul,
refl,
end
/-- (implementation) the right unitor for R-modules -/
def right_unitor (M : Module.{u} R) : Module.of R (M ⊗[R] R) ≅ M :=
(linear_equiv.to_Module_iso (tensor_product.rid R M) : of R (M ⊗ R) ≅ of R M).trans (of_self_iso M)
lemma right_unitor_naturality {M N : Module R} (f : M ⟶ N) :
tensor_hom f (𝟙 (Module.of R R)) ≫ (right_unitor N).hom = (right_unitor M).hom ≫ f :=
begin
ext x y, simp,
erw [tensor_product.rid_tmul, tensor_product.rid_tmul],
rw linear_map.map_smul,
refl,
end
lemma triangle (M N : Module.{u} R) :
(associator M (Module.of R R) N).hom ≫ tensor_hom (𝟙 M) (left_unitor N).hom =
tensor_hom (right_unitor M).hom (𝟙 N) :=
begin
apply tensor_product.ext_threefold,
intros x y z,
change R at y,
dsimp [tensor_hom, associator],
erw [tensor_product.lid_tmul, tensor_product.rid_tmul],
exact (tensor_product.smul_tmul _ _ _).symm
end
end monoidal_category
open monoidal_category
instance monoidal_category : monoidal_category (Module.{u} R) :=
{ -- data
tensor_obj := tensor_obj,
tensor_hom := @tensor_hom _ _,
tensor_unit := Module.of R R,
associator := associator,
left_unitor := left_unitor,
right_unitor := right_unitor,
-- properties
tensor_id' := λ M N, tensor_id M N,
tensor_comp' := λ M N K M' N' K' f g h, tensor_comp f g h,
associator_naturality' := λ M N K M' N' K' f g h, associator_naturality f g h,
left_unitor_naturality' := λ M N f, left_unitor_naturality f,
right_unitor_naturality' := λ M N f, right_unitor_naturality f,
pentagon' := λ M N K L, pentagon M N K L,
triangle' := λ M N, triangle M N, }
/-- Remind ourselves that the monoidal unit, being just `R`, is still a commutative ring. -/
instance : comm_ring ((𝟙_ (Module.{u} R) : Module.{u} R) : Type u) :=
(by apply_instance : comm_ring R)
namespace monoidal_category
@[simp]
lemma hom_apply {K L M N : Module.{u} R} (f : K ⟶ L) (g : M ⟶ N) (k : K) (m : M) :
(f ⊗ g) (k ⊗ₜ m) = f k ⊗ₜ g m := rfl
@[simp]
lemma left_unitor_hom_apply {M : Module.{u} R} (r : R) (m : M) :
((λ_ M).hom : 𝟙_ (Module R) ⊗ M ⟶ M) (r ⊗ₜ[R] m) = r • m :=
tensor_product.lid_tmul m r
@[simp]
lemma right_unitor_hom_apply {M : Module.{u} R} (m : M) (r : R) :
((ρ_ M).hom : M ⊗ 𝟙_ (Module R) ⟶ M) (m ⊗ₜ r) = r • m :=
tensor_product.rid_tmul m r
@[simp]
lemma associator_hom_apply {M N K : Module.{u} R} (m : M) (n : N) (k : K) :
((α_ M N K).hom : (M ⊗ N) ⊗ K ⟶ M ⊗ (N ⊗ K)) ((m ⊗ₜ n) ⊗ₜ k) = (m ⊗ₜ (n ⊗ₜ k)) := rfl
end monoidal_category
/-- (implementation) the braiding for R-modules -/
def braiding (M N : Module R) : tensor_obj M N ≅ tensor_obj N M :=
linear_equiv.to_Module_iso (tensor_product.comm R M N)
@[simp] lemma braiding_naturality {X₁ X₂ Y₁ Y₂ : Module.{u} R} (f : X₁ ⟶ Y₁) (g : X₂ ⟶ Y₂) :
(f ⊗ g) ≫ (Y₁.braiding Y₂).hom =
(X₁.braiding X₂).hom ≫ (g ⊗ f) :=
begin
apply tensor_product.ext',
intros x y,
refl
end
@[simp] lemma hexagon_forward (X Y Z : Module.{u} R) :
(α_ X Y Z).hom ≫ (braiding X _).hom ≫ (α_ Y Z X).hom =
((braiding X Y).hom ⊗ 𝟙 Z) ≫ (α_ Y X Z).hom ≫ (𝟙 Y ⊗ (braiding X Z).hom) :=
begin
apply tensor_product.ext_threefold,
intros x y z,
refl,
end
@[simp] lemma hexagon_reverse (X Y Z : Module.{u} R) :
(α_ X Y Z).inv ≫ (braiding _ Z).hom ≫ (α_ Z X Y).inv =
(𝟙 X ⊗ (Y.braiding Z).hom) ≫ (α_ X Z Y).inv ≫ ((X.braiding Z).hom ⊗ 𝟙 Y) :=
begin
apply (cancel_epi (α_ X Y Z).hom).1,
apply tensor_product.ext_threefold,
intros x y z,
refl,
end
local attribute [ext] tensor_product.ext
/-- The symmetric monoidal structure on `Module R`. -/
instance symmetric_category : symmetric_category (Module.{u} R) :=
{ braiding := braiding,
braiding_naturality' := λ X₁ X₂ Y₁ Y₂ f g, braiding_naturality f g,
hexagon_forward' := hexagon_forward,
hexagon_reverse' := hexagon_reverse, }
namespace monoidal_category
@[simp] lemma braiding_hom_apply {M N : Module.{u} R} (m : M) (n : N) :
((β_ M N).hom : M ⊗ N ⟶ N ⊗ M) (m ⊗ₜ n) = n ⊗ₜ m := rfl
@[simp] lemma braiding_inv_apply {M N : Module.{u} R} (m : M) (n : N) :
((β_ M N).inv : N ⊗ M ⟶ M ⊗ N) (n ⊗ₜ m) = m ⊗ₜ n := rfl
end monoidal_category
end Module
|
c2d9f5aecbf2f4707e1c0b3fe499b8e3a6951d58 | 957a80ea22c5abb4f4670b250d55534d9db99108 | /tests/lean/param.lean | 3eb77067a8d16314c1cab41c9330c3d4189f8251 | [
"Apache-2.0"
] | permissive | GaloisInc/lean | aa1e64d604051e602fcf4610061314b9a37ab8cd | f1ec117a24459b59c6ff9e56a1d09d9e9e60a6c0 | refs/heads/master | 1,592,202,909,807 | 1,504,624,387,000 | 1,504,624,387,000 | 75,319,626 | 2 | 1 | Apache-2.0 | 1,539,290,164,000 | 1,480,616,104,000 | C++ | UTF-8 | Lean | false | false | 494 | lean | --
definition foo1 a b c := a + b + (c:nat)
definition foo2 (a : nat) b c := a + b + c
definition foo3 a b (c : nat) := a + b + c
definition foo4 (a b c : nat) := a + b + c
definition foo5 (a b c) : nat := a + b + c
definition foo6 {a b c} : nat := a + b + c
-- definition foo7 a b c : nat := a + b + c -- Error
definition foo8 (a b c : nat) : nat := a + b + c
definition foo9 (a : nat) (b : nat) (c : nat) : nat := a + b + c
definition foo10 (a : nat) b (c : nat) : nat := a + b + c
|
827f3d67164e80b061cfc768317a0871d60bfe14 | ce6917c5bacabee346655160b74a307b4a5ab620 | /src/ch4/ex0604.lean | 613ca24dc7cd8694a4bff96ee0e7a80724f4da67 | [] | no_license | Ailrun/Theorem_Proving_in_Lean | ae6a23f3c54d62d401314d6a771e8ff8b4132db2 | 2eb1b5caf93c6a5a555c79e9097cf2ba5a66cf68 | refs/heads/master | 1,609,838,270,467 | 1,586,846,743,000 | 1,586,846,743,000 | 240,967,761 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 1,031 | lean | namespace hidden
def divides (m n : ℕ) : Prop := ∃ k, m * k = n
instance : has_dvd nat := ⟨divides⟩
def even (n : ℕ) : Prop := 2 ∣ n -- You can enter the '∣' character by typing \mid
section
variables m n : ℕ
#check m ∣ n
#check m^n
#check even (m^n +3)
end
def prime (n : ℕ) : Prop := ∀ m : ℕ, m > 1 ∧ m < n → ¬ (m ∣ n)
def infinitely_many_primes : Prop := ∀ n : ℕ, ∃ p : ℕ, prime p ∧ p > n
def Fermat_prime (n : ℕ) : Prop := (∃ m : ℕ, 2^(2^m) = n) ∧ prime n
def infinitely_many_Fermat_primes : Prop := ∀ n : ℕ, ∃ p : ℕ, Fermat_prime p ∧ p > n
def goldbach_conjecture : Prop := ∀ n : ℕ, n > 2 → even n → (∃ a b : ℕ, prime a ∧ prime b ∧ a + b = n)
def Goldbach's_weak_conjecture : Prop := ∀ n : ℕ, n > 5 → ¬ even n → (∃ a b c : ℕ, prime a ∧ prime b ∧ prime c ∧ a + b + c = n)
def Fermat's_last_theorem : Prop := ∀ n : ℕ, n > 2 → ¬ (∃ a b c : ℕ, a^n + b^n = c^n)
end hidden
|
6bd085fba085ea96154fc30388aac6f3a3946036 | 80cc5bf14c8ea85ff340d1d747a127dcadeb966f | /src/algebra/module/basic.lean | 51a41c8c7fc5c376527c76b52038b8551e90d7b8 | [
"Apache-2.0"
] | permissive | lacker/mathlib | f2439c743c4f8eb413ec589430c82d0f73b2d539 | ddf7563ac69d42cfa4a1bfe41db1fed521bd795f | refs/heads/master | 1,671,948,326,773 | 1,601,479,268,000 | 1,601,479,268,000 | 298,686,743 | 0 | 0 | Apache-2.0 | 1,601,070,794,000 | 1,601,070,794,000 | null | UTF-8 | Lean | false | false | 22,182 | lean | /-
Copyright (c) 2015 Nathaniel Thomas. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Nathaniel Thomas, Jeremy Avigad, Johannes Hölzl, Mario Carneiro
-/
import group_theory.group_action
/-!
# Modules over a ring
In this file we define
* `semimodule R M` : an additive commutative monoid `M` is a `semimodule` over a
`semiring` `R` if for `r : R` and `x : M` their "scalar multiplication `r • x : M` is defined, and
the operation `•` satisfies some natural associativity and distributivity axioms similar to those
on a ring.
* `module R M` : same as `semimodule R M` but assumes that `R` is a `ring` and `M` is an
additive commutative group.
* `vector_space k M` : same as `semimodule k M` and `module k M` but assumes that `k` is a `field`
and `M` is an additive commutative group.
* `linear_map R M M₂`, `M →ₗ[R] M₂` : a linear map between two R-`semimodule`s.
* `is_linear_map R f` : predicate saying that `f : M → M₂` is a linear map.
## Implementation notes
* `vector_space` and `module` are abbreviations for `semimodule R M`.
## Tags
semimodule, module, vector space, linear map
-/
open function
open_locale big_operators
universes u u' v w x y z
variables {R : Type u} {k : Type u'} {S : Type v} {M : Type w} {M₂ : Type x} {M₃ : Type y}
{ι : Type z}
/-- A semimodule is a generalization of vector spaces to a scalar semiring.
It consists of a scalar semiring `R` and an additive monoid of "vectors" `M`,
connected by a "scalar multiplication" operation `r • x : M`
(where `r : R` and `x : M`) with some natural associativity and
distributivity axioms similar to those on a ring. -/
@[protect_proj] class semimodule (R : Type u) (M : Type v) [semiring R]
[add_comm_monoid M] extends distrib_mul_action R M :=
(add_smul : ∀(r s : R) (x : M), (r + s) • x = r • x + s • x)
(zero_smul : ∀x : M, (0 : R) • x = 0)
section add_comm_monoid
variables [semiring R] [add_comm_monoid M] [semimodule R M] (r s : R) (x y : M)
theorem add_smul : (r + s) • x = r • x + s • x := semimodule.add_smul r s x
variables (R)
@[simp] theorem zero_smul : (0 : R) • x = 0 := semimodule.zero_smul x
theorem two_smul : (2 : R) • x = x + x := by rw [bit0, add_smul, one_smul]
/-- Pullback a `semimodule` structure along an injective additive monoid homomorphism. -/
protected def function.injective.semimodule [add_comm_monoid M₂] [has_scalar R M₂] (f : M₂ →+ M)
(hf : injective f) (smul : ∀ (c : R) x, f (c • x) = c • f x) :
semimodule R M₂ :=
{ smul := (•),
add_smul := λ c₁ c₂ x, hf $ by simp only [smul, f.map_add, add_smul],
zero_smul := λ x, hf $ by simp only [smul, zero_smul, f.map_zero],
.. hf.distrib_mul_action f smul }
/-- Pushforward a `semimodule` structure along a surjective additive monoid homomorphism. -/
protected def function.surjective.semimodule [add_comm_monoid M₂] [has_scalar R M₂] (f : M →+ M₂)
(hf : surjective f) (smul : ∀ (c : R) x, f (c • x) = c • f x) :
semimodule R M₂ :=
{ smul := (•),
add_smul := λ c₁ c₂ x, by { rcases hf x with ⟨x, rfl⟩,
simp only [add_smul, ← smul, ← f.map_add] },
zero_smul := λ x, by { rcases hf x with ⟨x, rfl⟩, simp only [← f.map_zero, ← smul, zero_smul] },
.. hf.distrib_mul_action f smul }
variable (M)
/-- `(•)` as an `add_monoid_hom`. -/
def smul_add_hom : R →+ M →+ M :=
{ to_fun := const_smul_hom M,
map_zero' := add_monoid_hom.ext $ λ r, by simp,
map_add' := λ x y, add_monoid_hom.ext $ λ r, by simp [add_smul] }
variables {R M}
@[simp] lemma smul_add_hom_apply (r : R) (x : M) :
smul_add_hom R M r x = r • x := rfl
lemma semimodule.eq_zero_of_zero_eq_one (zero_eq_one : (0 : R) = 1) : x = 0 :=
by rw [←one_smul R x, ←zero_eq_one, zero_smul]
lemma list.sum_smul {l : list R} {x : M} : l.sum • x = (l.map (λ r, r • x)).sum :=
((smul_add_hom R M).flip x).map_list_sum l
lemma multiset.sum_smul {l : multiset R} {x : M} : l.sum • x = (l.map (λ r, r • x)).sum :=
((smul_add_hom R M).flip x).map_multiset_sum l
lemma finset.sum_smul {f : ι → R} {s : finset ι} {x : M} :
(∑ i in s, f i) • x = (∑ i in s, (f i) • x) :=
((smul_add_hom R M).flip x).map_sum f s
end add_comm_monoid
section add_comm_group
variables (R M) [semiring R] [add_comm_group M]
/-- A structure containing most informations as in a semimodule, except the fields `zero_smul`
and `smul_zero`. As these fields can be deduced from the other ones when `M` is an `add_comm_group`,
this provides a way to construct a semimodule structure by checking less properties, in
`semimodule.of_core`. -/
@[nolint has_inhabited_instance]
structure semimodule.core extends has_scalar R M :=
(smul_add : ∀(r : R) (x y : M), r • (x + y) = r • x + r • y)
(add_smul : ∀(r s : R) (x : M), (r + s) • x = r • x + s • x)
(mul_smul : ∀(r s : R) (x : M), (r * s) • x = r • s • x)
(one_smul : ∀x : M, (1 : R) • x = x)
variables {R M}
/-- Define `semimodule` without proving `zero_smul` and `smul_zero` by using an auxiliary
structure `semimodule.core`, when the underlying space is an `add_comm_group`. -/
def semimodule.of_core (H : semimodule.core R M) : semimodule R M :=
by letI := H.to_has_scalar; exact
{ zero_smul := λ x, (add_monoid_hom.mk' (λ r : R, r • x) (λ r s, H.add_smul r s x)).map_zero,
smul_zero := λ r, (add_monoid_hom.mk' ((•) r) (H.smul_add r)).map_zero,
..H }
end add_comm_group
/--
Modules are defined as an `abbreviation` for semimodules,
if the base semiring is a ring.
(A previous definition made `module` a structure
defined to be `semimodule`.)
This has as advantage that modules are completely transparent
for type class inference, which means that all instances for semimodules
are immediately picked up for modules as well.
A cosmetic disadvantage is that one can not extend modules as such,
in definitions such as `normed_space`.
The solution is to extend `semimodule` instead.
-/
library_note "module definition"
/-- A module is the same as a semimodule, except the scalar semiring is actually
a ring.
This is the traditional generalization of spaces like `ℤ^n`, which have a natural
addition operation and a way to multiply them by elements of a ring, but no multiplication
operation between vectors. -/
abbreviation module (R : Type u) (M : Type v) [ring R] [add_comm_group M] :=
semimodule R M
/--
To prove two module structures on a fixed `add_comm_group` agree,
it suffices to check the scalar multiplications agree.
-/
-- We'll later use this to show `module ℤ M` is a subsingleton.
@[ext]
lemma module_ext {R : Type*} [ring R] {M : Type*} [add_comm_group M] (P Q : module R M)
(w : ∀ (r : R) (m : M), by { haveI := P, exact r • m } = by { haveI := Q, exact r • m }) :
P = Q :=
begin
unfreezingI { rcases P with ⟨⟨⟨⟨P⟩⟩⟩⟩, rcases Q with ⟨⟨⟨⟨Q⟩⟩⟩⟩ },
congr,
funext r m,
exact w r m,
all_goals { apply proof_irrel_heq },
end
section module
variables [ring R] [add_comm_group M] [module R M] (r s : R) (x y : M)
@[simp] theorem neg_smul : -r • x = - (r • x) :=
eq_neg_of_add_eq_zero (by rw [← add_smul, add_left_neg, zero_smul])
variables (R)
theorem neg_one_smul (x : M) : (-1 : R) • x = -x := by simp
variables {R}
theorem sub_smul (r s : R) (y : M) : (r - s) • y = r • y - s • y :=
by simp [add_smul, sub_eq_add_neg]
theorem smul_eq_zero {R E : Type*} [division_ring R] [add_comm_group E] [module R E]
{c : R} {x : E} :
c • x = 0 ↔ c = 0 ∨ x = 0 :=
⟨λ h, or_iff_not_imp_left.2 $ λ hc, (units.mk0 c hc).smul_eq_zero.1 h,
λ h, h.elim (λ hc, hc.symm ▸ zero_smul R x) (λ hx, hx.symm ▸ smul_zero c)⟩
end module
@[priority 910] -- see Note [lower instance priority]
instance semiring.to_semimodule [semiring R] : semimodule R R :=
{ smul := (*),
smul_add := mul_add,
add_smul := add_mul,
mul_smul := mul_assoc,
one_smul := one_mul,
zero_smul := zero_mul,
smul_zero := mul_zero }
@[simp] lemma smul_eq_mul [semiring R] {a a' : R} : a • a' = a * a' := rfl
/-- A ring homomorphism `f : R →+* M` defines a module structure by `r • x = f r * x`. -/
def ring_hom.to_semimodule [semiring R] [semiring S] (f : R →+* S) : semimodule R S :=
{ smul := λ r x, f r * x,
smul_add := λ r x y, by unfold has_scalar.smul; rw [mul_add],
add_smul := λ r s x, by unfold has_scalar.smul; rw [f.map_add, add_mul],
mul_smul := λ r s x, by unfold has_scalar.smul; rw [f.map_mul, mul_assoc],
one_smul := λ x, show f 1 * x = _, by rw [f.map_one, one_mul],
zero_smul := λ x, show f 0 * x = 0, by rw [f.map_zero, zero_mul],
smul_zero := λ r, mul_zero (f r) }
/-- A map `f` between semimodules over a semiring is linear if it satisfies the two properties
`f (x + y) = f x + f y` and `f (c • x) = c • f x`. The predicate `is_linear_map R f` asserts this
property. A bundled version is available with `linear_map`, and should be favored over
`is_linear_map` most of the time. -/
structure is_linear_map (R : Type u) {M : Type v} {M₂ : Type w}
[semiring R] [add_comm_monoid M] [add_comm_monoid M₂] [semimodule R M] [semimodule R M₂]
(f : M → M₂) : Prop :=
(map_add : ∀ x y, f (x + y) = f x + f y)
(map_smul : ∀ (c : R) x, f (c • x) = c • f x)
/-- A map `f` between semimodules over a semiring is linear if it satisfies the two properties
`f (x + y) = f x + f y` and `f (c • x) = c • f x`. Elements of `linear_map R M M₂` (available under
the notation `M →ₗ[R] M₂`) are bundled versions of such maps. An unbundled version is available with
the predicate `is_linear_map`, but it should be avoided most of the time. -/
structure linear_map (R : Type u) (M : Type v) (M₂ : Type w)
[semiring R] [add_comm_monoid M] [add_comm_monoid M₂] [semimodule R M] [semimodule R M₂] :=
(to_fun : M → M₂)
(map_add' : ∀x y, to_fun (x + y) = to_fun x + to_fun y)
(map_smul' : ∀(c : R) x, to_fun (c • x) = c • to_fun x)
infixr ` →ₗ `:25 := linear_map _
notation M ` →ₗ[`:25 R:25 `] `:0 M₂:0 := linear_map R M M₂
namespace linear_map
section add_comm_monoid
variables [semiring R] [add_comm_monoid M] [add_comm_monoid M₂] [add_comm_monoid M₃]
section
variables [semimodule R M] [semimodule R M₂]
instance : has_coe_to_fun (M →ₗ[R] M₂) := ⟨_, to_fun⟩
@[simp] lemma coe_mk (f : M → M₂) (h₁ h₂) :
((linear_map.mk f h₁ h₂ : M →ₗ[R] M₂) : M → M₂) = f := rfl
/-- Identity map as a `linear_map` -/
def id : M →ₗ[R] M :=
⟨id, λ _ _, rfl, λ _ _, rfl⟩
lemma id_apply (x : M) :
@id R M _ _ _ x = x := rfl
@[simp, norm_cast] lemma id_coe : ((linear_map.id : M →ₗ[R] M) : M → M) = _root_.id :=
by { ext x, refl }
end
section
-- We can infer the module structure implicitly from the linear maps,
-- rather than via typeclass resolution.
variables {semimodule_M : semimodule R M} {semimodule_M₂ : semimodule R M₂}
variables (f g : M →ₗ[R] M₂)
@[simp] lemma to_fun_eq_coe : f.to_fun = ⇑f := rfl
theorem is_linear : is_linear_map R f := ⟨f.2, f.3⟩
variables {f g}
theorem coe_inj (h : (f : M → M₂) = g) : f = g :=
by cases f; cases g; cases h; refl
@[ext] theorem ext (H : ∀ x, f x = g x) : f = g :=
coe_inj $ funext H
lemma coe_fn_congr : Π {x x' : M}, x = x' → f x = f x'
| _ _ rfl := rfl
theorem ext_iff : f = g ↔ ∀ x, f x = g x :=
⟨by { rintro rfl x, refl } , ext⟩
/-- If two linear maps are equal, they are equal at each point. -/
lemma lcongr_fun (h : f = g) (m : M) : f m = g m :=
congr_fun (congr_arg linear_map.to_fun h) m
variables (f g)
@[simp] lemma map_add (x y : M) : f (x + y) = f x + f y := f.map_add' x y
@[simp] lemma map_smul (c : R) (x : M) : f (c • x) = c • f x := f.map_smul' c x
@[simp] lemma map_zero : f 0 = 0 :=
by rw [← zero_smul R, map_smul f 0 0, zero_smul]
instance : is_add_monoid_hom f :=
{ map_add := map_add f,
map_zero := map_zero f }
/-- convert a linear map to an additive map -/
def to_add_monoid_hom : M →+ M₂ :=
{ to_fun := f,
map_zero' := f.map_zero,
map_add' := f.map_add }
@[simp] lemma to_add_monoid_hom_coe :
((f.to_add_monoid_hom) : M → M₂) = f := rfl
@[simp] lemma map_sum {ι} {t : finset ι} {g : ι → M} :
f (∑ i in t, g i) = (∑ i in t, f (g i)) :=
f.to_add_monoid_hom.map_sum _ _
end
section
variables {semimodule_M : semimodule R M} {semimodule_M₂ : semimodule R M₂}
{semimodule_M₃ : semimodule R M₃}
variables (f : M₂ →ₗ[R] M₃) (g : M →ₗ[R] M₂)
/-- Composition of two linear maps is a linear map -/
def comp : M →ₗ[R] M₃ := ⟨f ∘ g, by simp, by simp⟩
@[simp] lemma comp_apply (x : M) : f.comp g x = f (g x) := rfl
@[norm_cast]
lemma comp_coe : (f : M₂ → M₃) ∘ (g : M → M₂) = f.comp g := rfl
end
end add_comm_monoid
section add_comm_group
variables [semiring R] [add_comm_group M] [add_comm_group M₂]
variables {semimodule_M : semimodule R M} {semimodule_M₂ : semimodule R M₂}
variables (f : M →ₗ[R] M₂)
@[simp] lemma map_neg (x : M) : f (- x) = - f x :=
f.to_add_monoid_hom.map_neg x
@[simp] lemma map_sub (x y : M) : f (x - y) = f x - f y :=
f.to_add_monoid_hom.map_sub x y
instance : is_add_group_hom f :=
{ map_add := map_add f}
end add_comm_group
end linear_map
namespace is_linear_map
section add_comm_monoid
variables [semiring R] [add_comm_monoid M] [add_comm_monoid M₂]
variables [semimodule R M] [semimodule R M₂]
include R
/-- Convert an `is_linear_map` predicate to a `linear_map` -/
def mk' (f : M → M₂) (H : is_linear_map R f) : M →ₗ M₂ := ⟨f, H.1, H.2⟩
@[simp] theorem mk'_apply {f : M → M₂} (H : is_linear_map R f) (x : M) :
mk' f H x = f x := rfl
lemma is_linear_map_smul {R M : Type*} [comm_semiring R] [add_comm_monoid M] [semimodule R M] (c : R) :
is_linear_map R (λ (z : M), c • z) :=
begin
refine is_linear_map.mk (smul_add c) _,
intros _ _,
simp only [smul_smul, mul_comm]
end
--TODO: move
lemma is_linear_map_smul' {R M : Type*} [semiring R] [add_comm_monoid M] [semimodule R M] (a : M) :
is_linear_map R (λ (c : R), c • a) :=
is_linear_map.mk (λ x y, add_smul x y a) (λ x y, mul_smul x y a)
variables {f : M → M₂} (lin : is_linear_map R f)
include M M₂ lin
lemma map_zero : f (0 : M) = (0 : M₂) := (lin.mk' f).map_zero
end add_comm_monoid
section add_comm_group
variables [semiring R] [add_comm_group M] [add_comm_group M₂]
variables [semimodule R M] [semimodule R M₂]
include R
lemma is_linear_map_neg :
is_linear_map R (λ (z : M), -z) :=
is_linear_map.mk neg_add (λ x y, (smul_neg x y).symm)
variables {f : M → M₂} (lin : is_linear_map R f)
include M M₂ lin
lemma map_neg (x : M) : f (- x) = - f x := (lin.mk' f).map_neg x
lemma map_sub (x y) : f (x - y) = f x - f y := (lin.mk' f).map_sub x y
end add_comm_group
end is_linear_map
/-- Ring of linear endomorphismsms of a module. -/
abbreviation module.End (R : Type u) (M : Type v)
[semiring R] [add_comm_monoid M] [semimodule R M] := M →ₗ[R] M
/--
Vector spaces are defined as an `abbreviation` for semimodules,
if the base ring is a field.
(A previous definition made `vector_space` a structure
defined to be `module`.)
This has as advantage that vector spaces are completely transparent
for type class inference, which means that all instances for semimodules
are immediately picked up for vector spaces as well.
A cosmetic disadvantage is that one can not extend vector spaces as such,
in definitions such as `normed_space`.
The solution is to extend `semimodule` instead.
-/
library_note "vector space definition"
/-- A vector space is the same as a module, except the scalar ring is actually
a field. (This adds commutativity of the multiplication and existence of inverses.)
This is the traditional generalization of spaces like `ℝ^n`, which have a natural
addition operation and a way to multiply them by real numbers, but no multiplication
operation between vectors. -/
abbreviation vector_space (R : Type u) (M : Type v) [field R] [add_comm_group M] :=
semimodule R M
namespace add_comm_monoid
open add_monoid
variables [add_comm_monoid M]
/-- The natural ℕ-semimodule structure on any `add_comm_monoid`. -/
-- We don't make this a global instance, as it results in too many instances,
-- and confusing ambiguity in the notation `n • x` when `n : ℕ`.
def nat_semimodule : semimodule ℕ M :=
{ smul := nsmul,
smul_add := λ _ _ _, nsmul_add _ _ _,
add_smul := λ _ _ _, add_nsmul _ _ _,
mul_smul := λ _ _ _, mul_nsmul _ _ _,
one_smul := one_nsmul,
zero_smul := zero_nsmul,
smul_zero := nsmul_zero }
end add_comm_monoid
namespace add_comm_group
variables [add_comm_group M]
/-- The natural ℤ-module structure on any `add_comm_group`. -/
-- We don't immediately make this a global instance, as it results in too many instances,
-- and confusing ambiguity in the notation `n • x` when `n : ℤ`.
-- We do turn it into a global instance, but only at the end of this file,
-- and I remain dubious whether this is a good idea.
def int_module : module ℤ M :=
{ smul := gsmul,
smul_add := λ _ _ _, gsmul_add _ _ _,
add_smul := λ _ _ _, add_gsmul _ _ _,
mul_smul := λ _ _ _, gsmul_mul _ _ _,
one_smul := one_gsmul,
zero_smul := zero_gsmul,
smul_zero := gsmul_zero }
instance : subsingleton (module ℤ M) :=
begin
split,
intros P Q,
ext,
-- isn't that lovely: `r • m = r • m`
have one_smul : by { haveI := P, exact (1 : ℤ) • m } = by { haveI := Q, exact (1 : ℤ) • m },
begin
rw [@one_smul ℤ _ _ (by { haveI := P, apply_instance, }) m],
rw [@one_smul ℤ _ _ (by { haveI := Q, apply_instance, }) m],
end,
have nat_smul : ∀ n : ℕ, by { haveI := P, exact (n : ℤ) • m } = by { haveI := Q, exact (n : ℤ) • m },
begin
intro n,
induction n with n ih,
{ erw [zero_smul, zero_smul], },
{ rw [int.coe_nat_succ, add_smul, add_smul],
erw ih,
rw [one_smul], }
end,
cases r,
{ rw [int.of_nat_eq_coe, nat_smul], },
{ rw [int.neg_succ_of_nat_coe, neg_smul, neg_smul, nat_smul], }
end
end add_comm_group
section
local attribute [instance] add_comm_monoid.nat_semimodule
lemma semimodule.smul_eq_smul (R : Type*) [semiring R]
{M : Type*} [add_comm_monoid M] [semimodule R M]
(n : ℕ) (b : M) : n • b = (n : R) • b :=
begin
induction n with n ih,
{ rw [nat.cast_zero, zero_smul, zero_smul] },
{ change (n + 1) • b = (n + 1 : R) • b,
rw [add_smul, add_smul, one_smul, ih, one_smul] }
end
lemma semimodule.nsmul_eq_smul (R : Type*) [semiring R]
{M : Type*} [add_comm_monoid M] [semimodule R M] (n : ℕ) (b : M) :
n •ℕ b = (n : R) • b :=
semimodule.smul_eq_smul R n b
lemma nat.smul_def {M : Type*} [add_comm_monoid M] (n : ℕ) (x : M) :
n • x = n •ℕ x :=
rfl
end
section
local attribute [instance] add_comm_group.int_module
lemma gsmul_eq_smul {M : Type*} [add_comm_group M] (n : ℤ) (x : M) : gsmul n x = n • x := rfl
lemma module.gsmul_eq_smul_cast (R : Type*) [ring R] {M : Type*} [add_comm_group M] [module R M]
(n : ℤ) (b : M) : gsmul n b = (n : R) • b :=
begin
cases n,
{ apply semimodule.nsmul_eq_smul, },
{ dsimp,
rw semimodule.nsmul_eq_smul R,
push_cast,
rw neg_smul, }
end
lemma module.gsmul_eq_smul {M : Type*} [add_comm_group M] [module ℤ M]
(n : ℤ) (b : M) : gsmul n b = n • b :=
by rw [module.gsmul_eq_smul_cast ℤ, int.cast_id]
end
-- We prove this without using the `add_comm_group.int_module` instance, so the `•`s here
-- come from whatever the local `module ℤ` structure actually is.
lemma add_monoid_hom.map_int_module_smul
[add_comm_group M] [add_comm_group M₂]
[module ℤ M] [module ℤ M₂] (f : M →+ M₂) (x : ℤ) (a : M) : f (x • a) = x • f a :=
by simp only [← module.gsmul_eq_smul, f.map_gsmul]
lemma add_monoid_hom.map_int_cast_smul
[ring R] [add_comm_group M] [add_comm_group M₂] [module R M] [module R M₂]
(f : M →+ M₂) (x : ℤ) (a : M) : f ((x : R) • a) = (x : R) • f a :=
by simp only [← module.gsmul_eq_smul_cast, f.map_gsmul]
lemma add_monoid_hom.map_nat_cast_smul
[semiring R] [add_comm_monoid M] [add_comm_monoid M₂]
[semimodule R M] [semimodule R M₂] (f : M →+ M₂) (x : ℕ) (a : M) :
f ((x : R) • a) = (x : R) • f a :=
by simp only [← semimodule.nsmul_eq_smul, f.map_nsmul]
lemma add_monoid_hom.map_rat_cast_smul {R : Type*} [division_ring R] [char_zero R]
{E : Type*} [add_comm_group E] [module R E] {F : Type*} [add_comm_group F] [module R F]
(f : E →+ F) (c : ℚ) (x : E) :
f ((c : R) • x) = (c : R) • f x :=
begin
have : ∀ (x : E) (n : ℕ), 0 < n → f (((n⁻¹ : ℚ) : R) • x) = ((n⁻¹ : ℚ) : R) • f x,
{ intros x n hn,
replace hn : (n : R) ≠ 0 := nat.cast_ne_zero.2 (ne_of_gt hn),
conv_rhs { congr, skip, rw [← one_smul R x, ← mul_inv_cancel hn, mul_smul] },
rw [f.map_nat_cast_smul, smul_smul, rat.cast_inv, rat.cast_coe_nat,
inv_mul_cancel hn, one_smul] },
refine c.num_denom_cases_on (λ m n hn hmn, _),
rw [rat.mk_eq_div, div_eq_mul_inv, rat.cast_mul, int.cast_coe_nat, mul_smul, mul_smul,
rat.cast_coe_int, f.map_int_cast_smul, this _ n hn]
end
lemma add_monoid_hom.map_rat_module_smul {E : Type*} [add_comm_group E] [vector_space ℚ E]
{F : Type*} [add_comm_group F] [module ℚ F] (f : E →+ F) (c : ℚ) (x : E) :
f (c • x) = c • f x :=
rat.cast_id c ▸ f.map_rat_cast_smul c x
-- We finally turn on these instances globally:
attribute [instance] add_comm_monoid.nat_semimodule add_comm_group.int_module
/-- Reinterpret an additive homomorphism as a `ℤ`-linear map. -/
def add_monoid_hom.to_int_linear_map [add_comm_group M] [add_comm_group M₂] (f : M →+ M₂) :
M →ₗ[ℤ] M₂ :=
⟨f, f.map_add, f.map_int_module_smul⟩
/-- Reinterpret an additive homomorphism as a `ℚ`-linear map. -/
def add_monoid_hom.to_rat_linear_map [add_comm_group M] [vector_space ℚ M]
[add_comm_group M₂] [vector_space ℚ M₂] (f : M →+ M₂) :
M →ₗ[ℚ] M₂ :=
⟨f, f.map_add, f.map_rat_module_smul⟩
|
5c9b67ed12326091394a56cdf855eead53951bf4 | 3f7026ea8bef0825ca0339a275c03b911baef64d | /src/category_theory/limits/shapes/products.lean | e43e6f5aadb6d9485fd960002d09006488a6e727 | [
"Apache-2.0"
] | permissive | rspencer01/mathlib | b1e3afa5c121362ef0881012cc116513ab09f18c | c7d36292c6b9234dc40143c16288932ae38fdc12 | refs/heads/master | 1,595,010,346,708 | 1,567,511,503,000 | 1,567,511,503,000 | 206,071,681 | 0 | 0 | Apache-2.0 | 1,567,513,643,000 | 1,567,513,643,000 | null | UTF-8 | Lean | false | false | 3,126 | lean | /-
Copyright (c) 2018 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import category_theory.limits.limits
import category_theory.discrete_category
universes v u
open category_theory
namespace category_theory.limits
variables {β : Type v}
variables {C : Type u} [𝒞 : category.{v+1} C]
include 𝒞
-- We don't need an analogue of `pair` (for binary products), `parallel_pair` (for equalizers),
-- or `(co)span`, since we already have `functor.of_function`.
abbreviation fan (f : β → C) := cone (functor.of_function f)
abbreviation cofan (f : β → C) := cocone (functor.of_function f)
def fan.mk {f : β → C} {P : C} (p : Π b, P ⟶ f b) : fan f :=
{ X := P,
π := { app := p } }
def cofan.mk {f : β → C} {P : C} (p : Π b, f b ⟶ P) : cofan f :=
{ X := P,
ι := { app := p } }
@[simp] lemma fan.mk_π_app {f : β → C} {P : C} (p : Π b, P ⟶ f b) (b : β) : (fan.mk p).π.app b = p b := rfl
@[simp] lemma cofan.mk_π_app {f : β → C} {P : C} (p : Π b, f b ⟶ P) (b : β) : (cofan.mk p).ι.app b = p b := rfl
/-- `pi_obj f` computes the product of a family of elements `f`. (It is defined as an abbreviation
for `limit (functor.of_function f)`, so for most facts about `pi_obj f`, you will just use general facts
about limits.) -/
abbreviation pi_obj (f : β → C) [has_limit (functor.of_function f)] := limit (functor.of_function f)
/-- `sigma_obj f` computes the coproduct of a family of elements `f`. (It is defined as an abbreviation
for `colimit (functor.of_function f)`, so for most facts about `sigma_obj f`, you will just use general facts
about colimits.) -/
abbreviation sigma_obj (f : β → C) [has_colimit (functor.of_function f)] := colimit (functor.of_function f)
notation `∏ ` f:20 := pi_obj f
notation `∐ ` f:20 := sigma_obj f
abbreviation pi.π (f : β → C) [has_limit (functor.of_function f)] (b : β) : ∏ f ⟶ f b :=
limit.π (functor.of_function f) b
abbreviation sigma.ι (f : β → C) [has_colimit (functor.of_function f)] (b : β) : f b ⟶ ∐ f :=
colimit.ι (functor.of_function f) b
abbreviation pi.lift {f : β → C} [has_limit (functor.of_function f)] {P : C} (p : Π b, P ⟶ f b) : P ⟶ ∏ f :=
limit.lift _ (fan.mk p)
abbreviation sigma.desc {f : β → C} [has_colimit (functor.of_function f)] {P : C} (p : Π b, f b ⟶ P) : ∐ f ⟶ P :=
colimit.desc _ (cofan.mk p)
abbreviation pi.map {f g : β → C} [has_limits_of_shape.{v} (discrete β) C]
(p : Π b, f b ⟶ g b) : ∏ f ⟶ ∏ g :=
lim.map (nat_trans.of_function p)
abbreviation sigma.map {f g : β → C} [has_colimits_of_shape.{v} (discrete β) C]
(p : Π b, f b ⟶ g b) : ∐ f ⟶ ∐ g :=
colim.map (nat_trans.of_function p)
variables (C)
class has_products :=
(has_limits_of_shape : Π (J : Type v), has_limits_of_shape.{v} (discrete J) C)
class has_coproducts :=
(has_colimits_of_shape : Π (J : Type v), has_colimits_of_shape.{v} (discrete J) C)
attribute [instance] has_products.has_limits_of_shape has_coproducts.has_colimits_of_shape
end category_theory.limits
|
17b66c2b4d1cde0ca98d14207d05963f0dd99ae0 | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /tests/lean/run/1985.lean | b4e99347c6377833fac476e27982a8071b845880 | [
"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 | 632 | lean | import Lean.Data.Json
open Lean
deriving instance BEq for Except
example : Json.parse "\"\\u7406\\u79d1\"" == .ok "理科" := by native_decide
example : Json.parse "\"\\u7406\\u79D1\"" == .ok "理科" := by native_decide
example : Json.pretty "\x0b" == "\"\\u000b\"" := by native_decide
example : Json.pretty "\x1b" == "\"\\u001b\"" := by native_decide
example : Json.parse "\"\\u000b\"" == .ok "\x0b" := by native_decide
example : Json.parse "\"\\u001b\"" == .ok "\x1b" := by native_decide
example : Json.parse "\"\\u000B\"" == .ok "\x0b" := by native_decide
example : Json.parse "\"\\u001B\"" == .ok "\x1b" := by native_decide
|
e3e6fd52415f2bcd28f2992a4c1f738b8e8bf4c9 | 947fa6c38e48771ae886239b4edce6db6e18d0fb | /src/linear_algebra/finsupp_vector_space.lean | efc5670b9683f69230cf0c838d207403ca394bc4 | [
"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 | 7,537 | lean | /-
Copyright (c) 2019 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl
-/
import linear_algebra.dimension
import linear_algebra.finite_dimensional
import linear_algebra.std_basis
/-!
# Linear structures on function with finite support `ι →₀ M`
This file contains results on the `R`-module structure on functions of finite support from a type
`ι` to an `R`-module `M`, in particular in the case that `R` is a field.
Furthermore, it contains some facts about isomorphisms of vector spaces from equality of dimension
as well as the cardinality of finite dimensional vector spaces.
## TODO
Move the second half of this file to more appropriate other files.
-/
noncomputable theory
local attribute [instance, priority 100] classical.prop_decidable
open set linear_map submodule
open_locale cardinal
universes u v w
namespace finsupp
section ring
variables {R : Type*} {M : Type*} {ι : Type*}
variables [ring R] [add_comm_group M] [module R M]
lemma linear_independent_single {φ : ι → Type*}
{f : Π ι, φ ι → M} (hf : ∀i, linear_independent R (f i)) :
linear_independent R (λ ix : Σ i, φ i, single ix.1 (f ix.1 ix.2)) :=
begin
apply @linear_independent_Union_finite R _ _ _ _ ι φ (λ i x, single i (f i x)),
{ assume i,
have h_disjoint : disjoint (span R (range (f i))) (ker (lsingle i)),
{ rw ker_lsingle,
exact disjoint_bot_right },
apply (hf i).map h_disjoint },
{ intros i t ht hit,
refine (disjoint_lsingle_lsingle {i} t (disjoint_singleton_left.2 hit)).mono _ _,
{ rw span_le,
simp only [supr_singleton],
rw range_coe,
apply range_comp_subset_range },
{ refine supr₂_mono (λ i hi, _),
rw [span_le, range_coe],
apply range_comp_subset_range } }
end
end ring
section semiring
variables {R : Type*} {M : Type*} {ι : Type*}
variables [semiring R] [add_comm_monoid M] [module R M]
open linear_map submodule
/-- The basis on `ι →₀ M` with basis vectors `λ ⟨i, x⟩, single i (b i x)`. -/
protected def basis {φ : ι → Type*} (b : ∀ i, basis (φ i) R M) :
basis (Σ i, φ i) R (ι →₀ M) :=
basis.of_repr
{ to_fun := λ g,
{ to_fun := λ ix, (b ix.1).repr (g ix.1) ix.2,
support := g.support.sigma (λ i, ((b i).repr (g i)).support),
mem_support_to_fun := λ ix,
by { simp only [finset.mem_sigma, mem_support_iff, and_iff_right_iff_imp, ne.def],
intros b hg,
simpa [hg] using b } },
inv_fun := λ g,
{ to_fun := λ i, (b i).repr.symm (g.comap_domain _
(set.inj_on_of_injective sigma_mk_injective _)),
support := g.support.image sigma.fst,
mem_support_to_fun := λ i,
by { rw [ne.def, ← (b i).repr.injective.eq_iff, (b i).repr.apply_symm_apply, ext_iff],
simp only [exists_prop, linear_equiv.map_zero, comap_domain_apply, zero_apply,
exists_and_distrib_right, mem_support_iff, exists_eq_right, sigma.exists,
finset.mem_image, not_forall] } },
left_inv := λ g,
by { ext i, rw ← (b i).repr.injective.eq_iff, ext x,
simp only [coe_mk, linear_equiv.apply_symm_apply, comap_domain_apply] },
right_inv := λ g,
by { ext ⟨i, x⟩,
simp only [coe_mk, linear_equiv.apply_symm_apply, comap_domain_apply] },
map_add' := λ g h, by { ext ⟨i, x⟩, simp only [coe_mk, add_apply, linear_equiv.map_add] },
map_smul' := λ c h, by { ext ⟨i, x⟩, simp only [coe_mk, smul_apply, linear_equiv.map_smul,
ring_hom.id_apply] } }
@[simp] lemma basis_repr {φ : ι → Type*} (b : ∀ i, basis (φ i) R M)
(g : ι →₀ M) (ix) :
(finsupp.basis b).repr g ix = (b ix.1).repr (g ix.1) ix.2 :=
rfl
@[simp] lemma coe_basis {φ : ι → Type*} (b : ∀ i, basis (φ i) R M) :
⇑(finsupp.basis b) = λ (ix : Σ i, φ i), single ix.1 (b ix.1 ix.2) :=
funext $ λ ⟨i, x⟩, basis.apply_eq_iff.mpr $
begin
ext ⟨j, y⟩,
by_cases h : i = j,
{ cases h,
simp only [basis_repr, single_eq_same, basis.repr_self,
basis.finsupp.single_apply_left sigma_mk_injective] },
simp only [basis_repr, single_apply, h, false_and, if_false, linear_equiv.map_zero, zero_apply]
end
/-- The basis on `ι →₀ M` with basis vectors `λ i, single i 1`. -/
@[simps]
protected def basis_single_one :
basis ι R (ι →₀ R) :=
basis.of_repr (linear_equiv.refl _ _)
@[simp] lemma coe_basis_single_one :
(finsupp.basis_single_one : ι → (ι →₀ R)) = λ i, finsupp.single i 1 :=
funext $ λ i, basis.apply_eq_iff.mpr rfl
end semiring
section dim
variables {K : Type u} {V : Type v} {ι : Type v}
variables [field K] [add_comm_group V] [module K V]
lemma dim_eq : module.rank K (ι →₀ V) = #ι * module.rank K V :=
begin
let bs := basis.of_vector_space K V,
rw [← bs.mk_eq_dim'', ← (finsupp.basis (λa:ι, bs)).mk_eq_dim'',
cardinal.mk_sigma, cardinal.sum_const']
end
end dim
end finsupp
section module
variables {K : Type u} {V V₁ V₂ : Type v} {V' : Type w}
variables [field K]
variables [add_comm_group V] [module K V]
variables [add_comm_group V₁] [module K V₁]
variables [add_comm_group V₂] [module K V₂]
variables [add_comm_group V'] [module K V']
open module
lemma equiv_of_dim_eq_lift_dim
(h : cardinal.lift.{w} (module.rank K V) = cardinal.lift.{v} (module.rank K V')) :
nonempty (V ≃ₗ[K] V') :=
begin
haveI := classical.dec_eq V,
haveI := classical.dec_eq V',
let m := basis.of_vector_space K V,
let m' := basis.of_vector_space K V',
rw [←cardinal.lift_inj.1 m.mk_eq_dim, ←cardinal.lift_inj.1 m'.mk_eq_dim] at h,
rcases quotient.exact h with ⟨e⟩,
let e := (equiv.ulift.symm.trans e).trans equiv.ulift,
exact ⟨(m.repr ≪≫ₗ (finsupp.dom_lcongr e)) ≪≫ₗ m'.repr.symm⟩
end
/-- Two `K`-vector spaces are equivalent if their dimension is the same. -/
def equiv_of_dim_eq_dim (h : module.rank K V₁ = module.rank K V₂) : V₁ ≃ₗ[K] V₂ :=
begin
classical,
exact classical.choice (equiv_of_dim_eq_lift_dim (cardinal.lift_inj.2 h))
end
/-- An `n`-dimensional `K`-vector space is equivalent to `fin n → K`. -/
def fin_dim_vectorspace_equiv (n : ℕ)
(hn : (module.rank K V) = n) : V ≃ₗ[K] (fin n → K) :=
begin
have : cardinal.lift.{u} (n : cardinal.{v}) = cardinal.lift.{v} (n : cardinal.{u}),
by simp,
have hn := cardinal.lift_inj.{v u}.2 hn,
rw this at hn,
rw ←@dim_fin_fun K _ n at hn,
exact classical.choice (equiv_of_dim_eq_lift_dim hn),
end
end module
section module
open module
variables (K V : Type u) [field K] [add_comm_group V] [module K V]
lemma cardinal_mk_eq_cardinal_mk_field_pow_dim [finite_dimensional K V] :
#V = #K ^ module.rank K V :=
begin
let s := basis.of_vector_space_index K V,
let hs := basis.of_vector_space K V,
calc #V = #(s →₀ K) : quotient.sound ⟨hs.repr.to_equiv⟩
... = #(s → K) : quotient.sound ⟨finsupp.equiv_fun_on_fintype⟩
... = _ : by rw [← cardinal.lift_inj.1 hs.mk_eq_dim, cardinal.power_def]
end
lemma cardinal_lt_aleph_0_of_finite_dimensional [fintype K] [finite_dimensional K V] : #V < ℵ₀ :=
begin
letI : is_noetherian K V := is_noetherian.iff_fg.2 infer_instance,
rw cardinal_mk_eq_cardinal_mk_field_pow_dim K V,
exact cardinal.power_lt_aleph_0 (cardinal.lt_aleph_0_of_finite K)
(is_noetherian.dim_lt_aleph_0 K V),
end
end module
|
d6caa979ad92ee1112e481f4458b1da468b2e39f | c9ba4946202cfd1e2586e71960dfed00503dcdf4 | /src/meta_k/sort_schemas.lean | 079054db4b89b56c22136663fdc60ce9f5fc0427 | [] | no_license | ammkrn/learning_semantics_of_k | f55f669b369e32ef8407c16521b21ac5c106dc4d | c1487b538e1decc0f1fd389cd36bc36d2da012ab | refs/heads/master | 1,588,081,593,954 | 1,552,449,093,000 | 1,552,449,093,000 | 175,315,800 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 657 | lean | import .meta_sort
import .meta_symbol
import .meta_pattern
-- List {s}
def List : #Sort → #Sort
| s := #sort "List" (lift [s])
def Set : #Sort → #Sort
| carrier := #sort ( "Set") (lift [carrier])
def Bag : #Sort → #Sort
| carrier := #sort ( "Bag") (lift [carrier])
def Bag_p (s : #Sort) (h : meta_sort_name s ≠ ( "Bag_p")) : #Sort :=
#sort ( "Bag_p") (lift [s])
def Map : #Sort → #Sort → #Sort
| s s' := #sort ("Map") (lift [s, s'])
def Map_p (s : #Sort) (h : meta_sort_name s ≠ ( "Map_p")) : #Sort :=
#sort ( "Map_p") (lift [s])
def Context : #Sort → #Sort → #Sort
| s s' := #sort ( "Context") (lift [s, s'])
|
aa94ddb952e39159c57631d4734b379104956b4f | c9ba4946202cfd1e2586e71960dfed00503dcdf4 | /src/object_k/object_sort.lean | 542fe3b5e08fdc6c7e414d8a91c00430aca992b5 | [] | no_license | ammkrn/learning_semantics_of_k | f55f669b369e32ef8407c16521b21ac5c106dc4d | c1487b538e1decc0f1fd389cd36bc36d2da012ab | refs/heads/master | 1,588,081,593,954 | 1,552,449,093,000 | 1,552,449,093,000 | 175,315,800 | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 3,686 | lean | import meta_k.meta_sort
import meta_k.meta_pattern
import meta_k.meta_symbol
@[reducible]
def object_identifier := string
inductive object_sort_constructor
| mk : object_identifier → object_sort_constructor
inductive object_sort_variable
| mk : object_identifier → object_sort_variable
mutual inductive object_sort, object_sort_list
with object_sort : Type
| mk : object_sort_constructor → object_sort_list → object_sort
with object_sort_list : Type
| nil : object_sort_list
| cons : object_sort → object_sort_list → object_sort_list
open object_sort_constructor
open object_sort_variable
open object_sort
open object_sort_list
instance : decidable_eq object_sort_constructor := by tactic.mk_dec_eq_instance
instance : decidable_eq object_sort_variable := by tactic.mk_dec_eq_instance
instance : decidable_eq object_sort := by tactic.mk_dec_eq_instance
instance : decidable_eq object_sort_list := by tactic.mk_dec_eq_instance
def object_sort_constructor.to_string : object_sort_constructor → string
| (mk str) := str
def object_sort_variable.to_string : object_sort_variable → string
| (mk str) := str
instance : has_repr object_sort_constructor := ⟨ object_sort_constructor.to_string ⟩
instance : has_repr object_sort_variable := ⟨ object_sort_variable.to_string ⟩
-- #########################
notation `~Sort` := object_sort
notation `~SortList` := list object_sort
notation `~nilSortList` := object_sort_list.nil
notation `~consSortList` := object_sort_list.cons
notation `~sort` := object_sort.mk
class object_has_sort (α : Type) :=
(get_sort : α → object_sort)
def object_sort_list.to_list_object_sort : object_sort_list → ~SortList
| nil := []
| (cons hd tl) := hd :: (object_sort_list.to_list_object_sort tl)
mutual def object_sort_to_string, object_sort_list_to_string
with object_sort_to_string : object_sort → string
| (object_sort.mk ident L) := "Sort : (" ++ repr ident ++ ", " ++ (object_sort_list_to_string L) ++ "), "
with object_sort_list_to_string : object_sort_list → string
| (object_sort_list.nil) := "sort_ε"
| (object_sort_list.cons s l) := object_sort_to_string s ++ object_sort_list_to_string l
def pretty_object_sort_list_to_string : object_sort_list → string
| object_sort_list.nil := ""
| l := "[" ++ string.popn_back (object_sort_list_to_string l) 7 ++ "]"
instance : has_repr object_sort_list := ⟨ pretty_object_sort_list_to_string ⟩
def pretty_object_sort_to_string : object_sort → string
| (object_sort.mk ident object_sort_list.nil) := (repr ident)
| (object_sort.mk ident L) := (repr ident) ++ " : " ++ repr L
def object_sort_get_name : object_sort → string
| (object_sort.mk ident _) := (repr ident)
instance : has_repr object_sort := ⟨ pretty_object_sort_to_string ⟩
def list_object_sort.to_object_sort_list : ~SortList → object_sort_list
| [] := object_sort_list.nil
| (hd :: tl) := object_sort_list.cons hd (list_object_sort.to_object_sort_list tl)
instance object_sort_list_to_list_object_sort_lift :
has_lift object_sort_list (list object_sort) :=
⟨ object_sort_list.to_list_object_sort ⟩
instance list_object_sort_to_object_sort_list_lift :
has_lift (list object_sort) (object_sort_list) :=
⟨ list_object_sort.to_object_sort_list ⟩
def object_sort_params_for_class : object_sort → ~SortList
| (object_sort.mk ident L) := lift L
instance : is_Sort object_sort := ⟨ object_sort_params_for_class ⟩
instance : inhabited object_sort := ⟨ object_sort.mk ⟨"Nat"⟩ ~nilSortList ⟩
def name_fn : string → string
| "O" := "zero"
| "S" := "succ"
| "+" := "plus"
| "ε" := "nil"
| "::" := "cons"
| "@" := "append"
| s := s |
f8bd7414f0ce4693ad1da5456a21ec820b66b4db | 35677d2df3f081738fa6b08138e03ee36bc33cad | /src/algebra/group/with_one.lean | 72154a18de66bacddbee3122746c01afd9e2a164 | [
"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 | 7,500 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro, Johan Commelin
-/
import algebra.group.to_additive algebra.group.basic algebra.group.hom
universes u v
variable {α : Type u}
@[to_additive]
def with_one (α) := option α
namespace with_one
@[to_additive]
instance : monad with_one := option.monad
@[to_additive]
instance : has_one (with_one α) := ⟨none⟩
@[to_additive]
instance : inhabited (with_one α) := ⟨1⟩
@[to_additive]
instance : has_coe_t α (with_one α) := ⟨some⟩
@[simp, to_additive]
lemma one_ne_coe {a : α} : (1 : with_one α) ≠ a :=
λ h, option.no_confusion h
@[simp, to_additive]
lemma coe_ne_one {a : α} : (a : with_one α) ≠ (1 : with_one α) :=
λ h, option.no_confusion h
@[to_additive]
lemma ne_one_iff_exists : ∀ {x : with_one α}, x ≠ 1 ↔ ∃ (a : α), x = a
| 1 := ⟨λ h, false.elim $ h rfl, by { rintros ⟨a,ha⟩ h, simpa using h }⟩
| (a : α) := ⟨λ h, ⟨a, rfl⟩, λ h, with_one.coe_ne_one⟩
@[to_additive]
lemma coe_inj {a b : α} : (a : with_one α) = b ↔ a = b :=
option.some_inj
@[elab_as_eliminator, to_additive]
protected lemma cases_on {P : with_one α → Prop} :
∀ (x : with_one α), P 1 → (∀ a : α, P a) → P x :=
option.cases_on
@[to_additive]
instance [has_mul α] : has_mul (with_one α) :=
{ mul := option.lift_or_get (*) }
@[simp, to_additive]
lemma mul_coe [has_mul α] (a b : α) : (a : with_one α) * b = (a * b : α) := rfl
@[to_additive add_monoid]
instance [semigroup α] : monoid (with_one α) :=
{ mul_assoc := (option.lift_or_get_assoc _).1,
one_mul := (option.lift_or_get_is_left_id _).1,
mul_one := (option.lift_or_get_is_right_id _).1,
..with_one.has_one,
..with_one.has_mul }
@[to_additive add_comm_monoid]
instance [comm_semigroup α] : comm_monoid (with_one α) :=
{ mul_comm := (option.lift_or_get_comm _).1,
..with_one.monoid }
section lift
variables [semigroup α] {β : Type v} [monoid β]
/-- Lift a semigroup homomorphism `f` to a bundled monoid homorphism.
We have no bundled semigroup homomorphisms, so this function
takes `∀ x y, f (x * y) = f x * f y` as an explicit argument. -/
@[to_additive]
def lift (f : α → β) (hf : ∀ x y, f (x * y) = f x * f y) :
(with_one α) →* β :=
{ to_fun := λ x, option.cases_on x 1 f,
map_one' := rfl,
map_mul' := λ x y,
with_one.cases_on x (by { rw one_mul, exact (one_mul _).symm }) $ λ x,
with_one.cases_on y (by { rw mul_one, exact (mul_one _).symm }) $ λ y,
hf x y }
variables (f : α → β) (hf : ∀ x y, f (x * y) = f x * f y)
@[simp, to_additive]
lemma lift_coe (x : α) : lift f hf x = f x := rfl
@[simp, to_additive]
lemma lift_one : lift f hf 1 = 1 := rfl
@[to_additive]
theorem lift_unique (f : with_one α →* β) : f = lift (f ∘ coe) (λ x y, f.map_mul x y) :=
monoid_hom.ext $ λ x, with_one.cases_on x f.map_one $ λ x, rfl
end lift
section map
variables {β : Type v} [semigroup α] [semigroup β]
@[to_additive]
def map (f : α → β) (hf : ∀ x y, f (x * y) = f x * f y) :
with_one α →* with_one β :=
lift (coe ∘ f) (λ x y, coe_inj.2 $ hf x y)
end map
end with_one
namespace with_zero
instance [one : has_one α] : has_one (with_zero α) :=
{ ..one }
instance [has_one α] : zero_ne_one_class (with_zero α) :=
{ zero_ne_one := λ h, option.no_confusion h,
..with_zero.has_zero,
..with_zero.has_one }
lemma coe_one [has_one α] : ((1 : α) : with_zero α) = 1 := rfl
instance [has_mul α] : mul_zero_class (with_zero α) :=
{ mul := λ o₁ o₂, o₁.bind (λ a, option.map (λ b, a * b) o₂),
zero_mul := λ a, rfl,
mul_zero := λ a, by cases a; refl,
..with_zero.has_zero }
@[simp] lemma mul_coe [has_mul α] (a b : α) :
(a : with_zero α) * b = (a * b : α) := rfl
instance [semigroup α] : semigroup (with_zero α) :=
{ mul_assoc := λ a b c, match a, b, c with
| none, _, _ := rfl
| some a, none, _ := rfl
| some a, some b, none := rfl
| some a, some b, some c := congr_arg some (mul_assoc _ _ _)
end,
..with_zero.mul_zero_class }
instance [comm_semigroup α] : comm_semigroup (with_zero α) :=
{ mul_comm := λ a b, match a, b with
| none, _ := (mul_zero _).symm
| some a, none := rfl
| some a, some b := congr_arg some (mul_comm _ _)
end,
..with_zero.semigroup }
instance [monoid α] : monoid (with_zero α) :=
{ one_mul := λ a, match a with
| none := rfl
| some a := congr_arg some $ one_mul _
end,
mul_one := λ a, match a with
| none := rfl
| some a := congr_arg some $ mul_one _
end,
..with_zero.zero_ne_one_class,
..with_zero.semigroup }
instance [comm_monoid α] : comm_monoid (with_zero α) :=
{ ..with_zero.monoid, ..with_zero.comm_semigroup }
definition inv [has_inv α] (x : with_zero α) : with_zero α :=
do a ← x, return a⁻¹
instance [has_inv α] : has_inv (with_zero α) := ⟨with_zero.inv⟩
@[simp] lemma inv_coe [has_inv α] (a : α) :
(a : with_zero α)⁻¹ = (a⁻¹ : α) := rfl
@[simp] lemma inv_zero [has_inv α] :
(0 : with_zero α)⁻¹ = 0 := rfl
section group
variables [group α]
@[simp] lemma inv_one : (1 : with_zero α)⁻¹ = 1 :=
show ((1⁻¹ : α) : with_zero α) = 1, by simp [coe_one]
definition div (x y : with_zero α) : with_zero α :=
x * y⁻¹
instance : has_div (with_zero α) := ⟨with_zero.div⟩
@[simp] lemma zero_div (a : with_zero α) : 0 / a = 0 := rfl
@[simp] lemma div_zero (a : with_zero α) : a / 0 = 0 := by change a * _ = _; simp
lemma div_coe (a b : α) : (a : with_zero α) / b = (a * b⁻¹ : α) := rfl
lemma one_div (x : with_zero α) : 1 / x = x⁻¹ := one_mul _
@[simp] lemma div_one : ∀ (x : with_zero α), x / 1 = x
| 0 := rfl
| (a : α) := show _ * _ = _, by simp
@[simp] lemma mul_right_inv : ∀ (x : with_zero α) (h : x ≠ 0), x * x⁻¹ = 1
| 0 h := false.elim $ h rfl
| (a : α) h := by simp [coe_one]
@[simp] lemma mul_left_inv : ∀ (x : with_zero α) (h : x ≠ 0), x⁻¹ * x = 1
| 0 h := false.elim $ h rfl
| (a : α) h := by simp [coe_one]
@[simp] lemma mul_inv_rev : ∀ (x y : with_zero α), (x * y)⁻¹ = y⁻¹ * x⁻¹
| 0 0 := rfl
| 0 (b : α) := rfl
| (a : α) 0 := rfl
| (a : α) (b : α) := by simp
@[simp] lemma mul_div_cancel {a b : with_zero α} (hb : b ≠ 0) : a * b / b = a :=
show _ * _ * _ = _, by simp [mul_assoc, hb]
@[simp] lemma div_mul_cancel {a b : with_zero α} (hb : b ≠ 0) : a / b * b = a :=
show _ * _ * _ = _, by simp [mul_assoc, hb]
lemma div_eq_iff_mul_eq {a b c : with_zero α} (hb : b ≠ 0) : a / b = c ↔ c * b = a :=
by split; intro h; simp [h.symm, hb]
end group
section comm_group
variables [comm_group α] {a b c d : with_zero α}
lemma div_eq_div (hb : b ≠ 0) (hd : d ≠ 0) : a / b = c / d ↔ a * d = b * c :=
begin
rw ne_zero_iff_exists at hb hd,
rcases hb with ⟨b, rfl⟩,
rcases hd with ⟨d, rfl⟩,
induction a using with_zero.cases_on;
induction c using with_zero.cases_on,
{ refl },
{ simp [div_coe] },
{ simp [div_coe] },
erw [with_zero.coe_inj, with_zero.coe_inj],
show a * b⁻¹ = c * d⁻¹ ↔ a * d = b * c,
split; intro H,
{ rw mul_inv_eq_iff_eq_mul at H,
rw [H, mul_right_comm, inv_mul_cancel_right, mul_comm] },
{ rw [mul_inv_eq_iff_eq_mul, mul_right_comm, mul_comm c, ← H, mul_inv_cancel_right] }
end
end comm_group
end with_zero
|
173e8c1981ba2f8c98cdad3695f0d13dd02e3d13 | dd0f5513e11c52db157d2fcc8456d9401a6cd9da | /06_Inductive_Types.org.20.lean | b1e606100a682f06adbd90334769a9297e371b03 | [] | 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 | 154 | lean | /- page 83 -/
import standard
namespace hide
-- BEGIN
inductive sigma {A : Type} (B : A → Type) :=
dpair : Π a : A, B a → sigma B
-- END
end hide
|
8ea20558a9c74b44d22ab287d146632369f1ea59 | 75db7e3219bba2fbf41bf5b905f34fcb3c6ca3f2 | /tests/lean/extra/597a.hlean | 4bed4467497f2bc2de31359431a89f6c9207358a | [
"Apache-2.0"
] | permissive | jroesch/lean | 30ef0860fa905d35b9ad6f76de1a4f65c9af6871 | 3de4ec1a6ce9a960feb2a48eeea8b53246fa34f2 | refs/heads/master | 1,586,090,835,348 | 1,455,142,203,000 | 1,455,142,277,000 | 51,536,958 | 1 | 0 | null | 1,455,215,811,000 | 1,455,215,811,000 | null | UTF-8 | Lean | false | false | 96 | hlean | open equiv
open equiv.ops
constants (A B : Type₀) (f : A ≃ B)
definition foo : A → B := f
|
8a19f1343c8270aadd675e84cef3568df0982cbd | e0f9ba56b7fedc16ef8697f6caeef5898b435143 | /src/algebra/direct_sum.lean | ff425fec3fed0a4bd2c834810e97eac99cc12277 | [
"Apache-2.0"
] | permissive | anrddh/mathlib | 6a374da53c7e3a35cb0298b0cd67824efef362b4 | a4266a01d2dcb10de19369307c986d038c7bb6a6 | refs/heads/master | 1,656,710,827,909 | 1,589,560,456,000 | 1,589,560,456,000 | 264,271,800 | 0 | 0 | Apache-2.0 | 1,589,568,062,000 | 1,589,568,061,000 | null | UTF-8 | Lean | false | false | 6,315 | lean | /-
Copyright (c) 2019 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau
Direct sum of abelian groups, indexed by a discrete type.
-/
import data.dfinsupp
universes u v w u₁
variables (ι : Type v) [decidable_eq ι] (β : ι → Type w) [Π i, add_comm_group (β i)]
def direct_sum : Type* := Π₀ i, β i
namespace direct_sum
variables {ι β}
instance : add_comm_group (direct_sum ι β) :=
dfinsupp.add_comm_group
instance : inhabited (direct_sum ι β) := ⟨0⟩
variables β
def mk : Π s : finset ι, (Π i : (↑s : set ι), β i.1) → direct_sum ι β :=
dfinsupp.mk
def of : Π i : ι, β i → direct_sum ι β :=
dfinsupp.single
variables {β}
instance mk.is_add_group_hom (s : finset ι) : is_add_group_hom (mk β s) :=
{ map_add := λ _ _, dfinsupp.mk_add }
@[simp] lemma mk_zero (s : finset ι) : mk β s 0 = 0 :=
is_add_group_hom.map_zero _
@[simp] lemma mk_add (s : finset ι) (x y) : mk β s (x + y) = mk β s x + mk β s y :=
is_add_hom.map_add _ x y
@[simp] lemma mk_neg (s : finset ι) (x) : mk β s (-x) = -mk β s x :=
is_add_group_hom.map_neg _ x
@[simp] lemma mk_sub (s : finset ι) (x y) : mk β s (x - y) = mk β s x - mk β s y :=
is_add_group_hom.map_sub _ x y
instance of.is_add_group_hom (i : ι) : is_add_group_hom (of β i) :=
{ map_add := λ _ _, dfinsupp.single_add }
@[simp] lemma of_zero (i : ι) : of β i 0 = 0 :=
is_add_group_hom.map_zero _
@[simp] lemma of_add (i : ι) (x y) : of β i (x + y) = of β i x + of β i y :=
is_add_hom.map_add _ x y
@[simp] lemma of_neg (i : ι) (x) : of β i (-x) = -of β i x :=
is_add_group_hom.map_neg _ x
@[simp] lemma of_sub (i : ι) (x y) : of β i (x - y) = of β i x - of β i y :=
is_add_group_hom.map_sub _ x y
theorem mk_inj (s : finset ι) : function.injective (mk β s) :=
dfinsupp.mk_inj s
theorem of_inj (i : ι) : function.injective (of β i) :=
λ x y H, congr_fun (mk_inj _ H) ⟨i, by simp⟩
@[elab_as_eliminator]
protected theorem induction_on {C : direct_sum ι β → Prop}
(x : direct_sum ι β) (H_zero : C 0)
(H_basic : ∀ (i : ι) (x : β i), C (of β i x))
(H_plus : ∀ x y, C x → C y → C (x + y)) : C x :=
begin
apply dfinsupp.induction x H_zero,
intros i b f h1 h2 ih,
solve_by_elim
end
variables {γ : Type u₁} [add_comm_group γ]
variables (φ : Π i, β i → γ) [Π i, is_add_group_hom (φ i)]
variables (φ)
def to_group (f : direct_sum ι β) : γ :=
quotient.lift_on f (λ x, x.2.to_finset.sum $ λ i, φ i (x.1 i)) $ λ x y H,
begin
have H1 : x.2.to_finset ∩ y.2.to_finset ⊆ x.2.to_finset, from finset.inter_subset_left _ _,
have H2 : x.2.to_finset ∩ y.2.to_finset ⊆ y.2.to_finset, from finset.inter_subset_right _ _,
refine (finset.sum_subset H1 _).symm.trans ((finset.sum_congr rfl _).trans (finset.sum_subset H2 _)),
{ intros i H1 H2, rw finset.mem_inter at H2, rw H i,
simp only [multiset.mem_to_finset] at H1 H2,
rw [(y.3 i).resolve_left (mt (and.intro H1) H2), is_add_group_hom.map_zero (φ i)] },
{ intros i H1, rw H i },
{ intros i H1 H2, rw finset.mem_inter at H2, rw ← H i,
simp only [multiset.mem_to_finset] at H1 H2,
rw [(x.3 i).resolve_left (mt (λ H3, and.intro H3 H1) H2), is_add_group_hom.map_zero (φ i)] }
end
variables {φ}
instance to_group.is_add_group_hom : is_add_group_hom (to_group φ) :=
{ map_add := assume f g,
begin
refine quotient.induction_on f (λ x, _),
refine quotient.induction_on g (λ y, _),
change finset.sum _ _ = finset.sum _ _ + finset.sum _ _,
simp only, conv { to_lhs, congr, skip, funext, rw is_add_hom.map_add (φ i) },
simp only [finset.sum_add_distrib],
congr' 1,
{ refine (finset.sum_subset _ _).symm,
{ intro i, simp only [multiset.mem_to_finset, multiset.mem_add], exact or.inl },
{ intros i H1 H2, simp only [multiset.mem_to_finset, multiset.mem_add] at H2,
rw [(x.3 i).resolve_left H2, is_add_group_hom.map_zero (φ i)] } },
{ refine (finset.sum_subset _ _).symm,
{ intro i, simp only [multiset.mem_to_finset, multiset.mem_add], exact or.inr },
{ intros i H1 H2, simp only [multiset.mem_to_finset, multiset.mem_add] at H2,
rw [(y.3 i).resolve_left H2, is_add_group_hom.map_zero (φ i)] } }
end }
variables (φ)
@[simp] lemma to_group_zero : to_group φ 0 = 0 :=
is_add_group_hom.map_zero _
@[simp] lemma to_group_add (x y) : to_group φ (x + y) = to_group φ x + to_group φ y :=
is_add_hom.map_add _ x y
@[simp] lemma to_group_neg (x) : to_group φ (-x) = -to_group φ x :=
is_add_group_hom.map_neg _ x
@[simp] lemma to_group_sub (x y) : to_group φ (x - y) = to_group φ x - to_group φ y :=
is_add_group_hom.map_sub _ x y
@[simp] lemma to_group_of (i) (x : β i) : to_group φ (of β i x) = φ i x :=
(add_zero _).trans $ congr_arg (φ i) $ show (if H : i ∈ finset.singleton i then x else 0) = x,
from dif_pos $ finset.mem_singleton_self i
variables (ψ : direct_sum ι β → γ) [is_add_group_hom ψ]
theorem to_group.unique (f : direct_sum ι β) :
ψ f = @to_group _ _ _ _ _ _ (λ i, ψ ∘ of β i) (λ i, is_add_group_hom.comp (of β i) ψ) f :=
by haveI : ∀ i, is_add_group_hom (ψ ∘ of β i) := (λ _, is_add_group_hom.comp _ _); exact
direct_sum.induction_on f
(by rw [is_add_group_hom.map_zero ψ, is_add_group_hom.map_zero (to_group (λ i, ψ ∘ of β i))])
(λ i x, by rw [to_group_of])
(λ x y ihx ihy, by rw [is_add_hom.map_add ψ, is_add_hom.map_add (to_group (λ i, ψ ∘ of β i)), ihx, ihy])
variables (β)
def set_to_set (S T : set ι) (H : S ⊆ T) :
direct_sum S (β ∘ subtype.val) → direct_sum T (β ∘ subtype.val) :=
to_group $ λ i, of (β ∘ @subtype.val _ T) ⟨i.1, H i.2⟩
variables {β}
instance (S T : set ι) (H : S ⊆ T) : is_add_group_hom (set_to_set β S T H) :=
to_group.is_add_group_hom
protected def id (M : Type v) [add_comm_group M] : direct_sum punit (λ _, M) ≃ M :=
{ to_fun := direct_sum.to_group (λ _, id),
inv_fun := of (λ _, M) punit.star,
left_inv := λ x, direct_sum.induction_on x
(by rw [to_group_zero, of_zero])
(λ ⟨⟩ x, by rw [to_group_of]; refl)
(λ x y ihx ihy, by rw [to_group_add, of_add, ihx, ihy]),
right_inv := λ x, to_group_of _ _ _ }
instance : has_coe_to_fun (direct_sum ι β) :=
dfinsupp.has_coe_to_fun
end direct_sum
|
c28fcdba82cf27a8b3add344b8ff04881a41ddb5 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/category_theory/category/Kleisli.lean | 2dd2d7d5c431a09397e07364ca7a6a511d73b611 | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 1,626 | lean | /-
Copyright (c) 2018 Simon Hudon. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Simon Hudon
-/
import category_theory.category.basic
/-!
# The Kleisli construction on the Type category
Define the Kleisli category for (control) monads.
`category_theory/monad/kleisli` defines the general version for a monad on `C`, and demonstrates
the equivalence between the two.
## TODO
Generalise this to work with category_theory.monad
-/
universes u v
namespace category_theory
/-- The Kleisli category on the (type-)monad `m`. Note that the monad is not assumed to be lawful
yet. -/
@[nolint unused_arguments]
def Kleisli (m : Type u → Type v) := Type u
/-- Construct an object of the Kleisli category from a type. -/
def Kleisli.mk (m) (α : Type u) : Kleisli m := α
instance Kleisli.category_struct {m} [monad.{u v} m] : category_struct (Kleisli m) :=
{ hom := λ α β, α → m β,
id := λ α x, pure x,
comp := λ X Y Z f g, f >=> g }
instance Kleisli.category {m} [monad.{u v} m] [is_lawful_monad m] : category (Kleisli m) :=
by refine { id_comp' := _, comp_id' := _, assoc' := _ };
intros; ext; unfold_projs; simp only [(>=>)] with functor_norm
@[simp] lemma Kleisli.id_def {m} [monad m] (α : Kleisli m) :
𝟙 α = @pure m _ α := rfl
lemma Kleisli.comp_def {m} [monad m] (α β γ : Kleisli m)
(xs : α ⟶ β) (ys : β ⟶ γ) (a : α) :
(xs ≫ ys) a = xs a >>= ys := rfl
instance : inhabited (Kleisli id) := ⟨punit⟩
instance {α : Type u} [inhabited α] : inhabited (Kleisli.mk id α) := ⟨show α, from default⟩
end category_theory
|
ee473633260002ab49f4a9f96d53d5e7296abd32 | 5749d8999a76f3a8fddceca1f6941981e33aaa96 | /src/topology/algebra/module.lean | cb81ce0d47112e19bd51b4a8cb5f2e599a55561c | [
"Apache-2.0"
] | permissive | jdsalchow/mathlib | 13ab43ef0d0515a17e550b16d09bd14b76125276 | 497e692b946d93906900bb33a51fd243e7649406 | refs/heads/master | 1,585,819,143,348 | 1,580,072,892,000 | 1,580,072,892,000 | 154,287,128 | 0 | 0 | Apache-2.0 | 1,540,281,610,000 | 1,540,281,609,000 | null | UTF-8 | Lean | false | false | 18,432 | lean | /-
Copyright (c) 2019 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jan-David Salchow, Sébastien Gouëzel, Jean Lo
-/
import topology.algebra.ring linear_algebra.basic ring_theory.algebra
/-!
# Theory of topological modules and continuous linear maps.
We define classes `topological_semimodule`, `topological_module` and `topological_vector_spaces`,
as extensions of the corresponding algebraic classes where the algebraic operations are continuous.
We also define continuous linear maps, as linear maps between topological modules which are
continuous. The set of continuous linear maps between the topological `R`-modules `M` and `M₂` is
denoted by `M →L[R] M₂`.
Continuous linear equivalences are denoted by `M ≃L[R] M₂`.
## Implementation notes
Topological vector spaces are defined as an `abbreviation` for topological modules,
if the base ring is a field. This has as advantage that topological vector spaces are completely
transparent for type class inference, which means that all instances for topological modules
are immediately picked up for vector spaces as well.
A cosmetic disadvantage is that one can not extend topological vector spaces.
The solution is to extend `topological_module` instead.
-/
open topological_space
universes u v w u'
section prio
set_option default_priority 100 -- see Note [default priority]
/-- A topological semimodule, over a semiring which is also a topological space, is a
semimodule in which scalar multiplication is continuous. In applications, R will be a topological
semiring and M a topological additive semigroup, but this is not needed for the definition -/
class topological_semimodule (R : Type u) (M : Type v)
[semiring R] [topological_space R]
[topological_space M] [add_comm_monoid M]
[semimodule R M] : Prop :=
(continuous_smul : continuous (λp : R × M, p.1 • p.2))
end prio
section
variables {R : Type u} {M : Type v}
[semiring R] [topological_space R]
[topological_space M] [add_comm_monoid M]
[semimodule R M] [topological_semimodule R M]
lemma continuous_smul : continuous (λp:R×M, p.1 • p.2) :=
topological_semimodule.continuous_smul R M
lemma continuous.smul {M₂ : Type*} [topological_space M₂] {f : M₂ → R} {g : M₂ → M}
(hf : continuous f) (hg : continuous g) : continuous (λp, f p • g p) :=
continuous_smul.comp (hf.prod_mk hg)
end
section prio
set_option default_priority 100 -- see Note [default priority]
/-- A topological module, over a ring which is also a topological space, is a module in which
scalar multiplication is continuous. In applications, `R` will be a topological ring and `M` a
topological additive group, but this is not needed for the definition -/
class topological_module (R : Type u) (M : Type v)
[ring R] [topological_space R]
[topological_space M] [add_comm_group M]
[module R M]
extends topological_semimodule R M : Prop
/-- A topological vector space is a topological module over a field. -/
abbreviation topological_vector_space (R : Type u) (M : Type v)
[discrete_field R] [topological_space R]
[topological_space M] [add_comm_group M] [module R M] :=
topological_module R M
end prio
section
variables {R : Type*} {M : Type*}
[ring R] [topological_space R]
[topological_space M] [add_comm_group M]
[module R M] [topological_module R M]
/-- Scalar multiplication by a unit is a homeomorphism from a
topological module onto itself. -/
protected def homeomorph.smul_of_unit (a : units R) : M ≃ₜ M :=
{ to_fun := λ x, (a : R) • x,
inv_fun := λ x, ((a⁻¹ : units R) : R) • x,
right_inv := λ x, calc (a : R) • ((a⁻¹ : units R) : R) • x = x :
by rw [smul_smul, units.mul_inv, one_smul],
left_inv := λ x, calc ((a⁻¹ : units R) : R) • (a : R) • x = x :
by rw [smul_smul, units.inv_mul, one_smul],
continuous_to_fun := continuous_const.smul continuous_id,
continuous_inv_fun := continuous_const.smul continuous_id }
lemma is_open_map_smul_of_unit (a : units R) : is_open_map (λ (x : M), (a : R) • x) :=
(homeomorph.smul_of_unit a).is_open_map
lemma is_closed_map_smul_of_unit (a : units R) : is_closed_map (λ (x : M), (a : R) • x) :=
(homeomorph.smul_of_unit a).is_closed_map
end
section
variables {R : Type*} {M : Type*} {a : R}
[discrete_field R] [topological_space R]
[topological_space M] [add_comm_group M]
[vector_space R M] [topological_vector_space R M]
set_option class.instance_max_depth 36
/-- Scalar multiplication by a non-zero field element is a
homeomorphism from a topological vector space onto itself. -/
protected def homeomorph.smul_of_ne_zero (ha : a ≠ 0) : M ≃ₜ M :=
{.. homeomorph.smul_of_unit ((equiv.units_equiv_ne_zero _).inv_fun ⟨_, ha⟩)}
lemma is_open_map_smul_of_ne_zero (ha : a ≠ 0) : is_open_map (λ (x : M), a • x) :=
(homeomorph.smul_of_ne_zero ha).is_open_map
lemma is_closed_map_smul_of_ne_zero (ha : a ≠ 0) : is_closed_map (λ (x : M), a • x) :=
(homeomorph.smul_of_ne_zero ha).is_closed_map
end
/-- Continuous linear maps between modules. We only put the type classes that are necessary for the
definition, although in applications `M` and `M₂` will be topological modules over the topological
ring `R`. -/
structure continuous_linear_map
(R : Type*) [ring R]
(M : Type*) [topological_space M] [add_comm_group M]
(M₂ : Type*) [topological_space M₂] [add_comm_group M₂]
[module R M] [module R M₂]
extends linear_map R M M₂ :=
(cont : continuous to_fun)
notation M ` →L[`:25 R `] ` M₂ := continuous_linear_map R M M₂
/-- Continuous linear equivalences between modules. We only put the type classes that are necessary
for the definition, although in applications `M` and `M₂` will be topological modules over the
topological ring `R`. -/
structure continuous_linear_equiv
(R : Type*) [ring R]
(M : Type*) [topological_space M] [add_comm_group M]
(M₂ : Type*) [topological_space M₂] [add_comm_group M₂]
[module R M] [module R M₂]
extends linear_equiv R M M₂ :=
(continuous_to_fun : continuous to_fun)
(continuous_inv_fun : continuous inv_fun)
notation M ` ≃L[`:50 R `] ` M₂ := continuous_linear_equiv R M M₂
namespace continuous_linear_map
section general_ring
/- Properties that hold for non-necessarily commutative rings. -/
variables
{R : Type*} [ring R]
{M : Type*} [topological_space M] [add_comm_group M]
{M₂ : Type*} [topological_space M₂] [add_comm_group M₂]
{M₃ : Type*} [topological_space M₃] [add_comm_group M₃]
[module R M] [module R M₂] [module R M₃]
/-- Coerce continuous linear maps to linear maps. -/
instance : has_coe (M →L[R] M₂) (M →ₗ[R] M₂) := ⟨to_linear_map⟩
protected lemma continuous (f : M →L[R] M₂) : continuous f := f.2
/-- Coerce continuous linear maps to functions. -/
instance to_fun : has_coe_to_fun $ M →L[R] M₂ := ⟨_, λ f, f.to_fun⟩
@[ext] theorem ext {f g : M →L[R] M₂} (h : ∀ x, f x = g x) : f = g :=
by cases f; cases g; congr' 1; ext x; apply h
theorem ext_iff {f g : M →L[R] M₂} : f = g ↔ ∀ x, f x = g x :=
⟨λ h x, by rw h, by ext⟩
variables (c : R) (f g : M →L[R] M₂) (h : M₂ →L[R] M₃) (x y z : M)
-- make some straightforward lemmas available to `simp`.
@[simp] lemma map_zero : f (0 : M) = 0 := (to_linear_map _).map_zero
@[simp] lemma map_add : f (x + y) = f x + f y := (to_linear_map _).map_add _ _
@[simp] lemma map_sub : f (x - y) = f x - f y := (to_linear_map _).map_sub _ _
@[simp] lemma map_smul : f (c • x) = c • f x := (to_linear_map _).map_smul _ _
@[simp] lemma map_neg : f (-x) = - (f x) := (to_linear_map _).map_neg _
@[simp, squash_cast] lemma coe_coe : ((f : M →ₗ[R] M₂) : (M → M₂)) = (f : M → M₂) := rfl
/-- The continuous map that is constantly zero. -/
def zero : M →L[R] M₂ :=
⟨0, by exact continuous_const⟩
instance: has_zero (M →L[R] M₂) := ⟨zero⟩
@[simp] lemma zero_apply : (0 : M →L[R] M₂) x = 0 := rfl
@[simp, elim_cast] lemma coe_zero : ((0 : M →L[R] M₂) : M →ₗ[R] M₂) = 0 := rfl
/- no simp attribute on the next line as simp does not always simplify `0 x` to `0`
when `0` is the zero function, while it does for the zero continuous linear map,
and this is the most important property we care about. -/
@[elim_cast] lemma coe_zero' : ((0 : M →L[R] M₂) : M → M₂) = 0 := rfl
/-- the identity map as a continuous linear map. -/
def id : M →L[R] M :=
⟨linear_map.id, continuous_id⟩
instance : has_one (M →L[R] M) := ⟨id⟩
@[simp] lemma id_apply : (id : M →L[R] M) x = x := rfl
@[simp, elim_cast] lemma coe_id : ((id : M →L[R] M) : M →ₗ[R] M) = linear_map.id := rfl
@[simp, elim_cast] lemma coe_id' : ((id : M →L[R] M) : M → M) = _root_.id := rfl
@[simp] lemma one_apply : (1 : M →L[R] M) x = x := rfl
section add
variables [topological_add_group M₂]
instance : has_add (M →L[R] M₂) :=
⟨λ f g, ⟨f + g, f.2.add g.2⟩⟩
@[simp] lemma add_apply : (f + g) x = f x + g x := rfl
@[simp, move_cast] lemma coe_add : (((f + g) : M →L[R] M₂) : M →ₗ[R] M₂) = (f : M →ₗ[R] M₂) + g := rfl
@[move_cast] lemma coe_add' : (((f + g) : M →L[R] M₂) : M → M₂) = (f : M → M₂) + g := rfl
instance : has_neg (M →L[R] M₂) := ⟨λ f, ⟨-f, f.2.neg⟩⟩
@[simp] lemma neg_apply : (-f) x = - (f x) := rfl
@[simp, move_cast] lemma coe_neg : (((-f) : M →L[R] M₂) : M →ₗ[R] M₂) = -(f : M →ₗ[R] M₂) := rfl
@[move_cast] lemma coe_neg' : (((-f) : M →L[R] M₂) : M → M₂) = -(f : M → M₂) := rfl
instance : add_comm_group (M →L[R] M₂) :=
by refine {zero := 0, add := (+), neg := has_neg.neg, ..};
intros; ext; simp
@[simp] lemma sub_apply (x : M) : (f - g) x = f x - g x := rfl
@[simp, move_cast] lemma coe_sub : (((f - g) : M →L[R] M₂) : M →ₗ[R] M₂) = (f : M →ₗ[R] M₂) - g := rfl
@[simp, move_cast] lemma coe_sub' : (((f - g) : M →L[R] M₂) : M → M₂) = (f : M → M₂) - g := rfl
end add
/-- Composition of bounded linear maps. -/
def comp (g : M₂ →L[R] M₃) (f : M →L[R] M₂) : M →L[R] M₃ :=
⟨linear_map.comp g.to_linear_map f.to_linear_map, g.2.comp f.2⟩
@[simp, move_cast] lemma coe_comp : ((h.comp f) : (M →ₗ[R] M₃)) = (h : M₂ →ₗ[R] M₃).comp f := rfl
@[simp, move_cast] lemma coe_comp' : ((h.comp f) : (M → M₃)) = (h : M₂ → M₃) ∘ f := rfl
@[simp] theorem comp_id : f.comp id = f :=
ext $ λ x, rfl
@[simp] theorem id_comp : id.comp f = f :=
ext $ λ x, rfl
@[simp] theorem comp_zero : f.comp (0 : M₃ →L[R] M) = 0 :=
by { ext, simp }
@[simp] theorem zero_comp : (0 : M₂ →L[R] M₃).comp f = 0 :=
by { ext, simp }
@[simp] lemma comp_add [topological_add_group M₂] [topological_add_group M₃]
(g : M₂ →L[R] M₃) (f₁ f₂ : M →L[R] M₂) :
g.comp (f₁ + f₂) = g.comp f₁ + g.comp f₂ :=
by { ext, simp }
@[simp] lemma add_comp [topological_add_group M₃]
(g₁ g₂ : M₂ →L[R] M₃) (f : M →L[R] M₂) :
(g₁ + g₂).comp f = g₁.comp f + g₂.comp f :=
by { ext, simp }
instance : has_mul (M →L[R] M) := ⟨comp⟩
instance [topological_add_group M] : ring (M →L[R] M) :=
{ mul := (*),
one := 1,
mul_one := λ _, ext $ λ _, rfl,
one_mul := λ _, ext $ λ _, rfl,
mul_assoc := λ _ _ _, ext $ λ _, rfl,
left_distrib := λ _ _ _, ext $ λ _, map_add _ _ _,
right_distrib := λ _ _ _, ext $ λ _, linear_map.add_apply _ _ _,
..continuous_linear_map.add_comm_group }
/-- The cartesian product of two bounded linear maps, as a bounded linear map. -/
def prod (f₁ : M →L[R] M₂) (f₂ : M →L[R] M₃) : M →L[R] (M₂ × M₃) :=
{ cont := f₁.2.prod_mk f₂.2,
..f₁.to_linear_map.prod f₂.to_linear_map }
end general_ring
section comm_ring
variables
{R : Type*} [comm_ring R] [topological_space R]
{M : Type*} [topological_space M] [add_comm_group M]
{M₂ : Type*} [topological_space M₂] [add_comm_group M₂]
{M₃ : Type*} [topological_space M₃] [add_comm_group M₃]
[module R M] [module R M₂] [module R M₃] [topological_module R M₃]
instance : has_scalar R (M →L[R] M₃) :=
⟨λ c f, ⟨c • f, continuous_const.smul f.2⟩⟩
variables (c : R) (h : M₂ →L[R] M₃) (f g : M →L[R] M₂) (x y z : M)
@[simp] lemma smul_comp : (c • h).comp f = c • (h.comp f) := rfl
variable [topological_module R M₂]
@[simp] lemma smul_apply : (c • f) x = c • (f x) := rfl
@[simp, move_cast] lemma coe_apply : (((c • f) : M →L[R] M₂) : M →ₗ[R] M₂) = c • (f : M →ₗ[R] M₂) := rfl
@[move_cast] lemma coe_apply' : (((c • f) : M →L[R] M₂) : M → M₂) = c • (f : M → M₂) := rfl
@[simp] lemma comp_smul : h.comp (c • f) = c • (h.comp f) := by { ext, simp }
/-- The linear map `λ x, c x • f`. Associates to a scalar-valued linear map and an element of
`M₂` the `M₂`-valued linear map obtained by multiplying the two (a.k.a. tensoring by `M₂`) -/
def smul_right (c : M →L[R] R) (f : M₂) : M →L[R] M₂ :=
{ cont := c.2.smul continuous_const,
..c.to_linear_map.smul_right f }
@[simp]
lemma smul_right_apply {c : M →L[R] R} {f : M₂} {x : M} :
(smul_right c f : M → M₂) x = (c : M → R) x • f :=
rfl
@[simp]
lemma smul_right_one_one (c : R →L[R] M₂) : smul_right 1 ((c : R → M₂) 1) = c :=
by ext; simp [-continuous_linear_map.map_smul, (continuous_linear_map.map_smul _ _ _).symm]
@[simp]
lemma smul_right_one_eq_iff {f f' : M₂} :
smul_right (1 : R →L[R] R) f = smul_right 1 f' ↔ f = f' :=
⟨λ h, have (smul_right (1 : R →L[R] R) f : R → M₂) 1 = (smul_right (1 : R →L[R] R) f' : R → M₂) 1,
by rw h,
by simp at this; assumption,
by cc⟩
variable [topological_add_group M₂]
instance : module R (M →L[R] M₂) :=
{ smul_zero := λ _, ext $ λ _, smul_zero _,
zero_smul := λ _, ext $ λ _, zero_smul _ _,
one_smul := λ _, ext $ λ _, one_smul _ _,
mul_smul := λ _ _ _, ext $ λ _, mul_smul _ _ _,
add_smul := λ _ _ _, ext $ λ _, add_smul _ _ _,
smul_add := λ _ _ _, ext $ λ _, smul_add _ _ _ }
set_option class.instance_max_depth 55
instance : is_ring_hom (λ c : R, c • (1 : M₂ →L[R] M₂)) :=
{ map_one := one_smul _ _,
map_add := λ _ _, ext $ λ _, add_smul _ _ _,
map_mul := λ _ _, ext $ λ _, mul_smul _ _ _ }
instance : algebra R (M₂ →L[R] M₂) :=
{ to_fun := λ c, c • 1,
smul_def' := λ _ _, rfl,
commutes' := λ _ _, ext $ λ _, map_smul _ _ _ }
end comm_ring
end continuous_linear_map
namespace continuous_linear_equiv
variables {R : Type*} [ring R]
{M : Type*} [topological_space M] [add_comm_group M]
{M₂ : Type*} [topological_space M₂] [add_comm_group M₂]
{M₃ : Type*} [topological_space M₃] [add_comm_group M₃]
[module R M] [module R M₂] [module R M₃]
/-- A continuous linear equivalence induces a continuous linear map. -/
def to_continuous_linear_map (e : M ≃L[R] M₂) : M →L[R] M₂ :=
{ cont := e.continuous_to_fun,
..e.to_linear_equiv.to_linear_map }
/-- Coerce continuous linear equivs to continuous linear maps. -/
instance : has_coe (M ≃L[R] M₂) (M →L[R] M₂) := ⟨to_continuous_linear_map⟩
/-- Coerce continuous linear equivs to maps. -/
instance : has_coe_to_fun (M ≃L[R] M₂) := ⟨_, λ f, ((f : M →L[R] M₂) : M → M₂)⟩
@[simp] theorem coe_apply (e : M ≃L[R] M₂) (b : M) : (e : M →L[R] M₂) b = e b := rfl
@[squash_cast] lemma coe_coe (e : M ≃L[R] M₂) : ((e : M →L[R] M₂) : M → M₂) = e := rfl
@[ext] lemma ext {f g : M ≃L[R] M₂} (h : (f : M → M₂) = g) : f = g :=
begin
cases f; cases g,
simp only [],
ext x,
simp only [coe_fn_coe_base] at h,
induction h,
refl
end
/-- A continuous linear equivalence induces a homeomorphism. -/
def to_homeomorph (e : M ≃L[R] M₂) : M ≃ₜ M₂ := { ..e }
-- Make some straightforward lemmas available to `simp`.
@[simp] lemma map_zero (e : M ≃L[R] M₂) : e (0 : M) = 0 := (e : M →L[R] M₂).map_zero
@[simp] lemma map_add (e : M ≃L[R] M₂) (x y : M) : e (x + y) = e x + e y :=
(e : M →L[R] M₂).map_add x y
@[simp] lemma map_sub (e : M ≃L[R] M₂) (x y : M) : e (x - y) = e x - e y :=
(e : M →L[R] M₂).map_sub x y
@[simp] lemma map_smul (e : M ≃L[R] M₂) (c : R) (x : M) : e (c • x) = c • (e x) :=
(e : M →L[R] M₂).map_smul c x
@[simp] lemma map_neg (e : M ≃L[R] M₂) (x : M) : e (-x) = -e x := (e : M →L[R] M₂).map_neg x
@[simp] lemma map_eq_zero_iff (e : M ≃L[R] M₂) {x : M} : e x = 0 ↔ x = 0 :=
e.to_linear_equiv.map_eq_zero_iff
section
variable (M)
/-- The identity map as a continuous linear equivalence. -/
@[refl] protected def refl : M ≃L[R] M :=
{ continuous_to_fun := continuous_id,
continuous_inv_fun := continuous_id,
.. linear_equiv.refl M }
end
/-- The inverse of a continuous linear equivalence as a continuous linear equivalence-/
@[symm] protected def symm (e : M ≃L[R] M₂) : M₂ ≃L[R] M :=
{ continuous_to_fun := e.continuous_inv_fun,
continuous_inv_fun := e.continuous_to_fun,
.. e.to_linear_equiv.symm }
@[simp] lemma symm_to_linear_equiv (e : M ≃L[R] M₂) :
e.symm.to_linear_equiv = e.to_linear_equiv.symm :=
by { ext, refl }
/-- The composition of two continuous linear equivalences as a continuous linear equivalence. -/
@[trans] protected def trans (e₁ : M ≃L[R] M₂) (e₂ : M₂ ≃L[R] M₃) : M ≃L[R] M₃ :=
{ continuous_to_fun := e₂.continuous_to_fun.comp e₁.continuous_to_fun,
continuous_inv_fun := e₁.continuous_inv_fun.comp e₂.continuous_inv_fun,
.. e₁.to_linear_equiv.trans e₂.to_linear_equiv }
@[simp] lemma trans_to_linear_equiv (e₁ : M ≃L[R] M₂) (e₂ : M₂ ≃L[R] M₃) :
(e₁.trans e₂).to_linear_equiv = e₁.to_linear_equiv.trans e₂.to_linear_equiv :=
by { ext, refl }
@[simp] theorem apply_symm_apply (e : M ≃L[R] M₂) (c : M₂) : e (e.symm c) = c := e.1.6 c
@[simp] theorem symm_apply_apply (e : M ≃L[R] M₂) (b : M) : e.symm (e b) = b := e.1.5 b
@[simp] theorem coe_comp_coe_symm (e : M ≃L[R] M₂) :
(e : M →L[R] M₂).comp (e.symm : M₂ →L[R] M) = continuous_linear_map.id :=
continuous_linear_map.ext e.apply_symm_apply
@[simp] theorem coe_symm_comp_coe (e : M ≃L[R] M₂) :
(e.symm : M₂ →L[R] M).comp (e : M →L[R] M₂) = continuous_linear_map.id :=
continuous_linear_map.ext e.symm_apply_apply
end continuous_linear_equiv
|
c9d73a2fb1a4dba62a8e73981717ae88d2265a80 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/data/nat/with_bot.lean | 1b043f024d88fb327da79a071b7ba843036b5c30 | [] | 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 | 1,007 | 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 Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.data.nat.basic
import Mathlib.algebra.ordered_group
import Mathlib.PostPort
namespace Mathlib
/-!
# `with_bot ℕ`
Lemmas about the type of natural numbers with a bottom element adjoined.
-/
namespace nat
theorem with_bot.add_eq_zero_iff {n : with_bot ℕ} {m : with_bot ℕ} : n + m = 0 ↔ n = 0 ∧ m = 0 := sorry
theorem with_bot.add_eq_one_iff {n : with_bot ℕ} {m : with_bot ℕ} : n + m = 1 ↔ n = 0 ∧ m = 1 ∨ n = 1 ∧ m = 0 := sorry
@[simp] theorem with_bot.coe_nonneg {n : ℕ} : 0 ≤ ↑n :=
eq.mpr (id (Eq._oldrec (Eq.refl (0 ≤ ↑n)) (Eq.symm with_bot.coe_zero)))
(eq.mpr (id (Eq._oldrec (Eq.refl (↑0 ≤ ↑n)) (propext with_bot.coe_le_coe))) (zero_le n))
@[simp] theorem with_bot.lt_zero_iff (n : with_bot ℕ) : n < 0 ↔ n = ⊥ := sorry
|
c3eb9a0bac9928cbbf91f8569d3c7488bbffd846 | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/group_theory/abelianization.lean | bf32cb1c68bc00368d5695216d8e087f812781cc | [
"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 | 10,351 | lean | /-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau, Michael Howes
-/
import data.finite.card
import group_theory.commutator
import group_theory.finiteness
/-!
# The abelianization of a group
This file defines the commutator and the abelianization of a group. It furthermore prepares for the
result that the abelianization is left adjoint to the forgetful functor from abelian groups to
groups, which can be found in `algebra/category/Group/adjunctions`.
## Main definitions
* `commutator`: defines the commutator of a group `G` as a subgroup of `G`.
* `abelianization`: defines the abelianization of a group `G` as the quotient of a group by its
commutator subgroup.
* `abelianization.map`: lifts a group homomorphism to a homomorphism between the abelianizations
* `mul_equiv.abelianization_congr`: Equivalent groups have equivalent abelianizations
-/
universes u v w
-- Let G be a group.
variables (G : Type u) [group G]
/-- The commutator subgroup of a group G is the normal subgroup
generated by the commutators [p,q]=`p*q*p⁻¹*q⁻¹`. -/
@[derive subgroup.normal]
def commutator : subgroup G :=
⁅(⊤ : subgroup G), ⊤⁆
lemma commutator_def : commutator G = ⁅(⊤ : subgroup G), ⊤⁆ := rfl
lemma commutator_eq_closure : commutator G = subgroup.closure (commutator_set G) :=
by simp [commutator, subgroup.commutator_def, commutator_set]
lemma commutator_eq_normal_closure :
commutator G = subgroup.normal_closure (commutator_set G) :=
by simp [commutator, subgroup.commutator_def', commutator_set]
instance commutator_characteristic : (commutator G).characteristic :=
subgroup.commutator_characteristic ⊤ ⊤
instance [finite (commutator_set G)] : group.fg (commutator G) :=
begin
rw commutator_eq_closure,
apply group.closure_finite_fg,
end
lemma rank_commutator_le_card [finite (commutator_set G)] :
group.rank (commutator G) ≤ nat.card (commutator_set G) :=
begin
rw subgroup.rank_congr (commutator_eq_closure G),
apply subgroup.rank_closure_finite_le_nat_card,
end
lemma commutator_centralizer_commutator_le_center :
⁅(commutator G).centralizer, (commutator G).centralizer⁆ ≤ subgroup.center G :=
begin
rw [←subgroup.centralizer_top, ←subgroup.commutator_eq_bot_iff_le_centralizer],
suffices : ⁅⁅⊤, (commutator G).centralizer⁆, (commutator G).centralizer⁆ = ⊥,
{ refine subgroup.commutator_commutator_eq_bot_of_rotate _ this,
rwa subgroup.commutator_comm (commutator G).centralizer },
rw [subgroup.commutator_comm, subgroup.commutator_eq_bot_iff_le_centralizer],
exact set.centralizer_subset (subgroup.commutator_mono le_top le_top),
end
/-- The abelianization of G is the quotient of G by its commutator subgroup. -/
def abelianization : Type u :=
G ⧸ (commutator G)
namespace abelianization
local attribute [instance] quotient_group.left_rel
instance : comm_group (abelianization G) :=
{ mul_comm := λ x y, quotient.induction_on₂' x y $ λ a b, quotient.sound' $
quotient_group.left_rel_apply.mpr $
subgroup.subset_closure ⟨b⁻¹, subgroup.mem_top b⁻¹, a⁻¹, subgroup.mem_top a⁻¹, by group⟩,
.. quotient_group.quotient.group _ }
instance : inhabited (abelianization G) := ⟨1⟩
instance [fintype G] [decidable_pred (∈ commutator G)] :
fintype (abelianization G) :=
quotient_group.fintype (commutator G)
instance [finite G] : finite (abelianization G) :=
quotient.finite _
variable {G}
/-- `of` is the canonical projection from G to its abelianization. -/
def of : G →* abelianization G :=
{ to_fun := quotient_group.mk,
map_one' := rfl,
map_mul' := λ x y, rfl }
@[simp] lemma mk_eq_of (a : G) : quot.mk _ a = of a := rfl
section lift
-- So far we have built Gᵃᵇ and proved it's an abelian group.
-- Furthremore we defined the canonical projection `of : G → Gᵃᵇ`
-- Let `A` be an abelian group and let `f` be a group homomorphism from `G` to `A`.
variables {A : Type v} [comm_group A] (f : G →* A)
lemma commutator_subset_ker : commutator G ≤ f.ker :=
begin
rw [commutator_eq_closure, subgroup.closure_le],
rintros x ⟨p, q, rfl⟩,
simp [monoid_hom.mem_ker, mul_right_comm (f p) (f q), commutator_element_def],
end
/-- If `f : G → A` is a group homomorphism to an abelian group, then `lift f` is the unique map from
the abelianization of a `G` to `A` that factors through `f`. -/
def lift : (G →* A) ≃ (abelianization G →* A) :=
{ to_fun := λ f, quotient_group.lift _ f (λ x h, f.mem_ker.2 $ commutator_subset_ker _ h),
inv_fun := λ F, F.comp of,
left_inv := λ f, monoid_hom.ext $ λ x, rfl,
right_inv := λ F, monoid_hom.ext $ λ x, quotient_group.induction_on x $ λ z, rfl }
@[simp] lemma lift.of (x : G) : lift f (of x) = f x :=
rfl
theorem lift.unique
(φ : abelianization G →* A)
-- hφ : φ agrees with f on the image of G in Gᵃᵇ
(hφ : ∀ (x : G), φ (of x) = f x)
{x : abelianization G} :
φ x = lift f x :=
quotient_group.induction_on x hφ
@[simp] lemma lift_of : lift of = monoid_hom.id (abelianization G) :=
lift.apply_symm_apply $ monoid_hom.id _
end lift
variables {A : Type v} [monoid A]
/-- See note [partially-applied ext lemmas]. -/
@[ext]
theorem hom_ext (φ ψ : abelianization G →* A)
(h : φ.comp of = ψ.comp of) : φ = ψ :=
monoid_hom.ext $ λ x, quotient_group.induction_on x $ monoid_hom.congr_fun h
section map
variables {H : Type v} [group H] (f : G →* H)
/-- The map operation of the `abelianization` functor -/
def map : abelianization G →* abelianization H := lift (of.comp f)
@[simp]
lemma map_of (x : G) : map f (of x) = of (f x) := rfl
@[simp]
lemma map_id : map (monoid_hom.id G) = monoid_hom.id (abelianization G) := hom_ext _ _ rfl
@[simp]
lemma map_comp {I : Type w} [group I] (g : H →* I) :
(map g).comp (map f) = map (g.comp f) := hom_ext _ _ rfl
@[simp]
lemma map_map_apply {I : Type w} [group I] {g : H →* I} {x : abelianization G}:
map g (map f x) = map (g.comp f) x := monoid_hom.congr_fun (map_comp _ _) x
end map
end abelianization
section abelianization_congr
variables {G} {H : Type v} [group H] (e : G ≃* H)
/-- Equivalent groups have equivalent abelianizations -/
def mul_equiv.abelianization_congr : abelianization G ≃* abelianization H :=
{ to_fun := abelianization.map e.to_monoid_hom,
inv_fun := abelianization.map e.symm.to_monoid_hom,
left_inv := by { rintros ⟨a⟩, simp },
right_inv := by { rintros ⟨a⟩, simp },
map_mul' := monoid_hom.map_mul _ }
@[simp]
lemma abelianization_congr_of (x : G) :
(e.abelianization_congr) (abelianization.of x) = abelianization.of (e x) := rfl
@[simp]
lemma abelianization_congr_refl :
(mul_equiv.refl G).abelianization_congr = mul_equiv.refl (abelianization G) :=
mul_equiv.to_monoid_hom_injective abelianization.lift_of
@[simp]
lemma abelianization_congr_symm :
e.abelianization_congr.symm = e.symm.abelianization_congr := rfl
@[simp]
lemma abelianization_congr_trans {I : Type v} [group I] (e₂ : H ≃* I) :
e.abelianization_congr.trans e₂.abelianization_congr = (e.trans e₂).abelianization_congr :=
mul_equiv.to_monoid_hom_injective (abelianization.hom_ext _ _ rfl)
end abelianization_congr
/-- An Abelian group is equivalent to its own abelianization. -/
@[simps] def abelianization.equiv_of_comm {H : Type*} [comm_group H] :
H ≃* abelianization H :=
{ to_fun := abelianization.of,
inv_fun := abelianization.lift (monoid_hom.id H),
left_inv := λ a, rfl,
right_inv := by { rintros ⟨a⟩, refl, },
.. abelianization.of }
section commutator_representatives
open subgroup
/-- Representatives `(g₁, g₂) : G × G` of commutator_set `⁅g₁, g₂⁆ ∈ G`. -/
def commutator_representatives : set (G × G) :=
set.range (λ g : commutator_set G, (g.2.some, g.2.some_spec.some))
instance [finite (commutator_set G)] : finite (commutator_representatives G) :=
set.finite_coe_iff.mpr (set.finite_range _)
/-- Subgroup generated by representatives `g₁ g₂ : G` of commutators `⁅g₁, g₂⁆ ∈ G`. -/
def closure_commutator_representatives : subgroup G :=
closure (prod.fst '' commutator_representatives G ∪ prod.snd '' commutator_representatives G)
instance closure_commutator_representatives_fg [finite (commutator_set G)] :
group.fg (closure_commutator_representatives G) :=
group.closure_finite_fg _
lemma rank_closure_commutator_representations_le [finite (commutator_set G)] :
group.rank (closure_commutator_representatives G) ≤ 2 * nat.card (commutator_set G) :=
begin
rw two_mul,
exact (subgroup.rank_closure_finite_le_nat_card _).trans ((set.card_union_le _ _).trans
(add_le_add ((finite.card_image_le _).trans (finite.card_range_le _))
((finite.card_image_le _).trans (finite.card_range_le _ )))),
end
lemma image_commutator_set_closure_commutator_representatives :
(closure_commutator_representatives G).subtype ''
(commutator_set (closure_commutator_representatives G)) = commutator_set G :=
begin
apply set.subset.antisymm,
{ rintros - ⟨-, ⟨g₁, g₂, rfl⟩, rfl⟩,
exact ⟨g₁, g₂, rfl⟩ },
{ exact λ g hg, ⟨_,
⟨⟨_, subset_closure (or.inl ⟨_, ⟨⟨g, hg⟩, rfl⟩, rfl⟩)⟩,
⟨_, subset_closure (or.inr ⟨_, ⟨⟨g, hg⟩, rfl⟩, rfl⟩)⟩,
rfl⟩,
hg.some_spec.some_spec⟩ },
end
lemma card_commutator_set_closure_commutator_representatives :
nat.card (commutator_set (closure_commutator_representatives G)) = nat.card (commutator_set G) :=
begin
rw ← image_commutator_set_closure_commutator_representatives G,
exact nat.card_congr (equiv.set.image _ _ (subtype_injective _)),
end
lemma card_commutator_closure_commutator_representatives :
nat.card (commutator (closure_commutator_representatives G)) = nat.card (commutator G) :=
begin
rw [commutator_eq_closure G, ←image_commutator_set_closure_commutator_representatives,
←monoid_hom.map_closure, ←commutator_eq_closure],
exact nat.card_congr (equiv.set.image _ _ (subtype_injective _)),
end
instance [finite (commutator_set G)] :
finite (commutator_set (closure_commutator_representatives G)) :=
begin
apply nat.finite_of_card_ne_zero,
rw card_commutator_set_closure_commutator_representatives,
exact finite.card_pos.ne',
end
end commutator_representatives
|
ae54fbf44b61faf31335da884f2f9f9b0f9676ca | dd36d7be956e3782ca434f598130c3243b02e195 | /Bench.lean | 7a7208fb60a54190fc9cd490426676ef4fb4950f | [] | no_license | joehendrix/lean-benchmark-experiments | 81c48322aa2b269af9078308b069e8e10788899e | 604815837cace1fc9ef8c36408c0abb377518aaa | refs/heads/master | 1,681,529,683,023 | 1,618,939,900,000 | 1,618,939,900,000 | 350,514,794 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 5,565 | lean | import Lean.Elab.Frontend
open Lean
-- Time with seconds and nanoseconds.
structure Timespec where
sec: UInt64
nsec: UInt64
@[extern 1 "lean_clock_monotonic_raw_gettime"]
constant clockMonotonicRawGettime : IO Timespec
/--
- @binAddBench n@ builds a balanced binary tree of height @n@ using additions of 1,
- and reduces them. It can be used to validate that reduction memoizes shared subterms.
-/
def binAddBench (n:Nat) : MetaM Unit := do
let z := mkConst `Nat.zero
let s := mkConst `Nat.succ
let p := mkConst `Nat.add
let mut r := mkApp s z
for i in [0:n] do
r := mkApp (mkApp p r) r
let r ← Lean.Meta.reduce r
pure ()
open IO
section
open Lean.Elab
-- Create environment from file
def environmentFromFile (fname:String) (moduleName:String) (opts : Options := {})
: IO (MessageLog × Environment) := do
let input ← IO.FS.readFile fname
let inputCtx := Parser.mkInputContext input fname
let (header, parserState, messages) ← Parser.parseHeader inputCtx
let (env, messages) ← processHeader header opts messages inputCtx
let env := env.setMainModule moduleName
let s ← IO.processCommands inputCtx parserState (Command.mkState env messages opts)
pure (s.commandState.messages, s.commandState.env)
end
def msecDiff (e s : Timespec) : String := do
let en : Nat := e.sec.toNat * 10^9 + e.nsec.toNat
let sn : Nat := s.sec.toNat * 10^9 + s.nsec.toNat
let musec := (en - sn) / 1000
let musecFrac := s!"{musec%1000}"
let musecPadding := "".pushn '0' (3 - musecFrac.length)
pure s!"{musec/1000}.{musecPadding}{musecFrac}"
-- This outputs how long it takes to run the given meta option in the
-- context created from the filename.
def benchmarkC (fname:String) (testName:String) (action:MetaM Unit) : IO Unit := do
let (msgs, env) ← environmentFromFile fname "Test"
if (← msgs.hasErrors) then
IO.println s!"Errors loading {fname}..."
for msg in msgs.toList do
IO.print s!" {← msg.toString (includeEndPos := Lean.Elab.getPrintMessageEndPos {})}"
else
IO.print s!"{testName} "
let s ← clockMonotonicRawGettime
let a ← (action.run.run {} {env := env}).toIO'
let e ← clockMonotonicRawGettime
IO.println s!"{msecDiff e s}ms"
match a with
| Except.error msg => do
IO.println s!" Error: {←msg.toMessageData.toString}"
| Except.ok _ => pure ()
@[extern "leanclock_io_timeit"] constant cppTime (fn : IO α) : IO (α × UInt64)
-- This outputs how long it takes to run the given meta option in the
-- context created from the filename.
def benchmarkCPP (fname:String) (testName:String) (action:MetaM Unit) : IO Unit := do
let (msgs, env) ← environmentFromFile fname "Test"
if (← msgs.hasErrors) then
IO.println s!"Errors loading {fname}..."
for msg in msgs.toList do
IO.print s!" {← msg.toString (includeEndPos := Lean.Elab.getPrintMessageEndPos {})}"
else
IO.print s!"{testName} "
let (a,t) ← cppTime (action.run.run {} {env := env}).toIO'
let musecFrac := s!"{t%1000}"
let musecPadding := "".pushn '0' (3 - musecFrac.length)
IO.println s!"{t/1000}.{musecPadding}{musecFrac}"
match a with
| Except.error msg => do
IO.println s!" Error: {←msg.toMessageData.toString}"
| Except.ok _ => pure ()
@[extern "leanclock_io_rusttime"] constant rustTime (fn : IO α) : IO (α × UInt64)
-- This outputs how long it takes to run the given meta option in the
-- context created from the filename.
def benchmarkRust (fname:String) (testName:String) (action:MetaM Unit) : IO Unit := do
let (msgs, env) ← environmentFromFile fname "Test"
if (← msgs.hasErrors) then
IO.println s!"Errors loading {fname}..."
for msg in msgs.toList do
IO.print s!" {← msg.toString (includeEndPos := Lean.Elab.getPrintMessageEndPos {})}"
else
IO.print s!"{testName} "
let (a,t) ← rustTime (action.run.run {} {env := env}).toIO'
let musecFrac := s!"{t%1000}"
let musecPadding := "".pushn '0' (3 - musecFrac.length)
IO.println s!"{t/1000}.{musecPadding}{musecFrac}"
match a with
| Except.error msg => do
IO.println s!" Error: {←msg.toMessageData.toString}"
| Except.ok _ => pure ()
-- This outputs how long it takes to run the given meta option in the
-- context created from the filename.
def benchmarkOrig (fname:String) (testName:String) (action:MetaM Unit) : IO Unit := do
let (msgs, env) ← environmentFromFile fname "Test"
if (← msgs.hasErrors) then
IO.println s!"Errors loading {fname}..."
for msg in msgs.toList do
IO.print s!" {← msg.toString (includeEndPos := Lean.Elab.getPrintMessageEndPos {})}"
else
IO.print s!"{testName} "
match ← timeit s!"{testName}" (action.run.run {} {env := env}).toIO' with
| Except.error msg => do
IO.println s!" Error: {←msg.toMessageData.toString}"
| Except.ok _ => pure ()
def benchmark := benchmarkRust
def main (args:List String) : IO Unit := do
match args with
| [path] => do
Lean.initSearchPath (some path)
benchmark "environments/initial.lean" "Binary add 30" (binAddBench 1)
benchmark "environments/initial.lean" "Binary add 60" (binAddBench 60)
benchmark "environments/initial.lean" "Binary add 200" (binAddBench 200)
benchmark "environments/initial.lean" "Binary add 2000" (binAddBench 2000)
| _ => do
IO.println "Please provide path to standard library, For example:"
IO.println " ./build/bin/Bench $HOME/.elan/toolchains/leanprover-lean4-nightly-2021-03-14/lib/lean" |
8c5e06b2e7539988d6fe2dd5c9eb3816ed2bc226 | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/analysis/calculus/local_extr.lean | 3e9e12996ac8e2527c0d7cc0918520245212e80c | [] | 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 | 13,844 | lean | /-
Copyright (c) 2019 Yury Kudryashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudryashov
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.topology.local_extr
import Mathlib.analysis.calculus.deriv
import Mathlib.PostPort
universes u
namespace Mathlib
/-!
# Local extrema of smooth functions
## Main definitions
In a real normed space `E` we define `pos_tangent_cone_at (s : set E) (x : E)`.
This would be the same as `tangent_cone_at ℝ≥0 s x` if we had a theory of normed semifields.
This set is used in the proof of Fermat's Theorem (see below), and can be used to formalize
[Lagrange multipliers](https://en.wikipedia.org/wiki/Lagrange_multiplier) and/or
[Karush–Kuhn–Tucker conditions](https://en.wikipedia.org/wiki/Karush–Kuhn–Tucker_conditions).
## Main statements
For each theorem name listed below, we also prove similar theorems for `min`, `extr` (if applicable)`,
and `(f)deriv` instead of `has_fderiv`.
* `is_local_max_on.has_fderiv_within_at_nonpos` : `f' y ≤ 0` whenever `a` is a local maximum
of `f` on `s`, `f` has derivative `f'` at `a` within `s`, and `y` belongs to the positive tangent
cone of `s` at `a`.
* `is_local_max_on.has_fderiv_within_at_eq_zero` : In the settings of the previous theorem, if both
`y` and `-y` belong to the positive tangent cone, then `f' y = 0`.
* `is_local_max.has_fderiv_at_eq_zero` :
[Fermat's Theorem](https://en.wikipedia.org/wiki/Fermat's_theorem_(stationary_points)),
the derivative of a differentiable function at a local extremum point equals zero.
* `exists_has_deriv_at_eq_zero` :
[Rolle's Theorem](https://en.wikipedia.org/wiki/Rolle's_theorem): given a function `f` continuous
on `[a, b]` and differentiable on `(a, b)`, there exists `c ∈ (a, b)` such that `f' c = 0`.
## Implementation notes
For each mathematical fact we prove several versions of its formalization:
* for maxima and minima;
* using `has_fderiv*`/`has_deriv*` or `fderiv*`/`deriv*`.
For the `fderiv*`/`deriv*` versions we omit the differentiability condition whenever it is possible
due to the fact that `fderiv` and `deriv` are defined to be zero for non-differentiable functions.
## References
* [Fermat's Theorem](https://en.wikipedia.org/wiki/Fermat's_theorem_(stationary_points));
* [Rolle's Theorem](https://en.wikipedia.org/wiki/Rolle's_theorem);
* [Tangent cone](https://en.wikipedia.org/wiki/Tangent_cone);
## Tags
local extremum, Fermat's Theorem, Rolle's Theorem
-/
/-- "Positive" tangent cone to `s` at `x`; the only difference from `tangent_cone_at`
is that we require `c n → ∞` instead of `∥c n∥ → ∞`. One can think about `pos_tangent_cone_at`
as `tangent_cone_at nnreal` but we have no theory of normed semifields yet. -/
def pos_tangent_cone_at {E : Type u} [normed_group E] [normed_space ℝ E] (s : set E) (x : E) : set E :=
set_of
fun (y : E) =>
∃ (c : ℕ → ℝ),
∃ (d : ℕ → E),
filter.eventually (fun (n : ℕ) => x + d n ∈ s) filter.at_top ∧
filter.tendsto c filter.at_top filter.at_top ∧
filter.tendsto (fun (n : ℕ) => c n • d n) filter.at_top (nhds y)
theorem pos_tangent_cone_at_mono {E : Type u} [normed_group E] [normed_space ℝ E] {a : E} : monotone fun (s : set E) => pos_tangent_cone_at s a := sorry
theorem mem_pos_tangent_cone_at_of_segment_subset {E : Type u} [normed_group E] [normed_space ℝ E] {s : set E} {x : E} {y : E} (h : segment x y ⊆ s) : y - x ∈ pos_tangent_cone_at s x := sorry
theorem pos_tangent_cone_at_univ {E : Type u} [normed_group E] [normed_space ℝ E] {a : E} : pos_tangent_cone_at set.univ a = set.univ := sorry
/-- If `f` has a local max on `s` at `a`, `f'` is the derivative of `f` at `a` within `s`, and
`y` belongs to the positive tangent cone of `s` at `a`, then `f' y ≤ 0`. -/
theorem is_local_max_on.has_fderiv_within_at_nonpos {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {f' : continuous_linear_map ℝ E ℝ} {s : set E} (h : is_local_max_on f s a) (hf : has_fderiv_within_at f f' s a) {y : E} (hy : y ∈ pos_tangent_cone_at s a) : coe_fn f' y ≤ 0 := sorry
/-- If `f` has a local max on `s` at `a` and `y` belongs to the positive tangent cone
of `s` at `a`, then `f' y ≤ 0`. -/
theorem is_local_max_on.fderiv_within_nonpos {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {s : set E} (h : is_local_max_on f s a) {y : E} (hy : y ∈ pos_tangent_cone_at s a) : coe_fn (fderiv_within ℝ f s a) y ≤ 0 := sorry
/-- If `f` has a local max on `s` at `a`, `f'` is a derivative of `f` at `a` within `s`, and
both `y` and `-y` belong to the positive tangent cone of `s` at `a`, then `f' y ≤ 0`. -/
theorem is_local_max_on.has_fderiv_within_at_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {f' : continuous_linear_map ℝ E ℝ} {s : set E} (h : is_local_max_on f s a) (hf : has_fderiv_within_at f f' s a) {y : E} (hy : y ∈ pos_tangent_cone_at s a) (hy' : -y ∈ pos_tangent_cone_at s a) : coe_fn f' y = 0 := sorry
/-- If `f` has a local max on `s` at `a` and both `y` and `-y` belong to the positive tangent cone
of `s` at `a`, then `f' y = 0`. -/
theorem is_local_max_on.fderiv_within_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {s : set E} (h : is_local_max_on f s a) {y : E} (hy : y ∈ pos_tangent_cone_at s a) (hy' : -y ∈ pos_tangent_cone_at s a) : coe_fn (fderiv_within ℝ f s a) y = 0 := sorry
/-- If `f` has a local min on `s` at `a`, `f'` is the derivative of `f` at `a` within `s`, and
`y` belongs to the positive tangent cone of `s` at `a`, then `0 ≤ f' y`. -/
theorem is_local_min_on.has_fderiv_within_at_nonneg {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {f' : continuous_linear_map ℝ E ℝ} {s : set E} (h : is_local_min_on f s a) (hf : has_fderiv_within_at f f' s a) {y : E} (hy : y ∈ pos_tangent_cone_at s a) : 0 ≤ coe_fn f' y := sorry
/-- If `f` has a local min on `s` at `a` and `y` belongs to the positive tangent cone
of `s` at `a`, then `0 ≤ f' y`. -/
theorem is_local_min_on.fderiv_within_nonneg {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {s : set E} (h : is_local_min_on f s a) {y : E} (hy : y ∈ pos_tangent_cone_at s a) : 0 ≤ coe_fn (fderiv_within ℝ f s a) y := sorry
/-- If `f` has a local max on `s` at `a`, `f'` is a derivative of `f` at `a` within `s`, and
both `y` and `-y` belong to the positive tangent cone of `s` at `a`, then `f' y ≤ 0`. -/
theorem is_local_min_on.has_fderiv_within_at_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {f' : continuous_linear_map ℝ E ℝ} {s : set E} (h : is_local_min_on f s a) (hf : has_fderiv_within_at f f' s a) {y : E} (hy : y ∈ pos_tangent_cone_at s a) (hy' : -y ∈ pos_tangent_cone_at s a) : coe_fn f' y = 0 := sorry
/-- If `f` has a local min on `s` at `a` and both `y` and `-y` belong to the positive tangent cone
of `s` at `a`, then `f' y = 0`. -/
theorem is_local_min_on.fderiv_within_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {s : set E} (h : is_local_min_on f s a) {y : E} (hy : y ∈ pos_tangent_cone_at s a) (hy' : -y ∈ pos_tangent_cone_at s a) : coe_fn (fderiv_within ℝ f s a) y = 0 := sorry
/-- Fermat's Theorem: the derivative of a function at a local minimum equals zero. -/
theorem is_local_min.has_fderiv_at_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {f' : continuous_linear_map ℝ E ℝ} (h : is_local_min f a) (hf : has_fderiv_at f f' a) : f' = 0 := sorry
/-- Fermat's Theorem: the derivative of a function at a local minimum equals zero. -/
theorem is_local_min.fderiv_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} (h : is_local_min f a) : fderiv ℝ f a = 0 :=
dite (differentiable_at ℝ f a)
(fun (hf : differentiable_at ℝ f a) => is_local_min.has_fderiv_at_eq_zero h (differentiable_at.has_fderiv_at hf))
fun (hf : ¬differentiable_at ℝ f a) => fderiv_zero_of_not_differentiable_at hf
/-- Fermat's Theorem: the derivative of a function at a local maximum equals zero. -/
theorem is_local_max.has_fderiv_at_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {f' : continuous_linear_map ℝ E ℝ} (h : is_local_max f a) (hf : has_fderiv_at f f' a) : f' = 0 :=
iff.mp neg_eq_zero (is_local_min.has_fderiv_at_eq_zero (is_local_max.neg h) (has_fderiv_at.neg hf))
/-- Fermat's Theorem: the derivative of a function at a local maximum equals zero. -/
theorem is_local_max.fderiv_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} (h : is_local_max f a) : fderiv ℝ f a = 0 :=
dite (differentiable_at ℝ f a)
(fun (hf : differentiable_at ℝ f a) => is_local_max.has_fderiv_at_eq_zero h (differentiable_at.has_fderiv_at hf))
fun (hf : ¬differentiable_at ℝ f a) => fderiv_zero_of_not_differentiable_at hf
/-- Fermat's Theorem: the derivative of a function at a local extremum equals zero. -/
theorem is_local_extr.has_fderiv_at_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} {f' : continuous_linear_map ℝ E ℝ} (h : is_local_extr f a) : has_fderiv_at f f' a → f' = 0 :=
is_local_extr.elim h is_local_min.has_fderiv_at_eq_zero is_local_max.has_fderiv_at_eq_zero
/-- Fermat's Theorem: the derivative of a function at a local extremum equals zero. -/
theorem is_local_extr.fderiv_eq_zero {E : Type u} [normed_group E] [normed_space ℝ E] {f : E → ℝ} {a : E} (h : is_local_extr f a) : fderiv ℝ f a = 0 :=
is_local_extr.elim h is_local_min.fderiv_eq_zero is_local_max.fderiv_eq_zero
/-- Fermat's Theorem: the derivative of a function at a local minimum equals zero. -/
theorem is_local_min.has_deriv_at_eq_zero {f : ℝ → ℝ} {f' : ℝ} {a : ℝ} (h : is_local_min f a) (hf : has_deriv_at f f' a) : f' = 0 := sorry
/-- Fermat's Theorem: the derivative of a function at a local minimum equals zero. -/
theorem is_local_min.deriv_eq_zero {f : ℝ → ℝ} {a : ℝ} (h : is_local_min f a) : deriv f a = 0 :=
dite (differentiable_at ℝ f a)
(fun (hf : differentiable_at ℝ f a) => is_local_min.has_deriv_at_eq_zero h (differentiable_at.has_deriv_at hf))
fun (hf : ¬differentiable_at ℝ f a) => deriv_zero_of_not_differentiable_at hf
/-- Fermat's Theorem: the derivative of a function at a local maximum equals zero. -/
theorem is_local_max.has_deriv_at_eq_zero {f : ℝ → ℝ} {f' : ℝ} {a : ℝ} (h : is_local_max f a) (hf : has_deriv_at f f' a) : f' = 0 :=
iff.mp neg_eq_zero (is_local_min.has_deriv_at_eq_zero (is_local_max.neg h) (has_deriv_at.neg hf))
/-- Fermat's Theorem: the derivative of a function at a local maximum equals zero. -/
theorem is_local_max.deriv_eq_zero {f : ℝ → ℝ} {a : ℝ} (h : is_local_max f a) : deriv f a = 0 :=
dite (differentiable_at ℝ f a)
(fun (hf : differentiable_at ℝ f a) => is_local_max.has_deriv_at_eq_zero h (differentiable_at.has_deriv_at hf))
fun (hf : ¬differentiable_at ℝ f a) => deriv_zero_of_not_differentiable_at hf
/-- Fermat's Theorem: the derivative of a function at a local extremum equals zero. -/
theorem is_local_extr.has_deriv_at_eq_zero {f : ℝ → ℝ} {f' : ℝ} {a : ℝ} (h : is_local_extr f a) : has_deriv_at f f' a → f' = 0 :=
is_local_extr.elim h is_local_min.has_deriv_at_eq_zero is_local_max.has_deriv_at_eq_zero
/-- Fermat's Theorem: the derivative of a function at a local extremum equals zero. -/
theorem is_local_extr.deriv_eq_zero {f : ℝ → ℝ} {a : ℝ} (h : is_local_extr f a) : deriv f a = 0 :=
is_local_extr.elim h is_local_min.deriv_eq_zero is_local_max.deriv_eq_zero
/-- A continuous function on a closed interval with `f a = f b` takes either its maximum
or its minimum value at a point in the interior of the interval. -/
theorem exists_Ioo_extr_on_Icc (f : ℝ → ℝ) {a : ℝ} {b : ℝ} (hab : a < b) (hfc : continuous_on f (set.Icc a b)) (hfI : f a = f b) : ∃ (c : ℝ), ∃ (H : c ∈ set.Ioo a b), is_extr_on f (set.Icc a b) c := sorry
/-- A continuous function on a closed interval with `f a = f b` has a local extremum at some
point of the corresponding open interval. -/
theorem exists_local_extr_Ioo (f : ℝ → ℝ) {a : ℝ} {b : ℝ} (hab : a < b) (hfc : continuous_on f (set.Icc a b)) (hfI : f a = f b) : ∃ (c : ℝ), ∃ (H : c ∈ set.Ioo a b), is_local_extr f c := sorry
/-- Rolle's Theorem `has_deriv_at` version -/
theorem exists_has_deriv_at_eq_zero (f : ℝ → ℝ) (f' : ℝ → ℝ) {a : ℝ} {b : ℝ} (hab : a < b) (hfc : continuous_on f (set.Icc a b)) (hfI : f a = f b) (hff' : ∀ (x : ℝ), x ∈ set.Ioo a b → has_deriv_at f (f' x) x) : ∃ (c : ℝ), ∃ (H : c ∈ set.Ioo a b), f' c = 0 := sorry
/-- Rolle's Theorem `deriv` version -/
theorem exists_deriv_eq_zero (f : ℝ → ℝ) {a : ℝ} {b : ℝ} (hab : a < b) (hfc : continuous_on f (set.Icc a b)) (hfI : f a = f b) : ∃ (c : ℝ), ∃ (H : c ∈ set.Ioo a b), deriv f c = 0 := sorry
theorem exists_has_deriv_at_eq_zero' {f : ℝ → ℝ} {f' : ℝ → ℝ} {a : ℝ} {b : ℝ} (hab : a < b) {l : ℝ} (hfa : filter.tendsto f (nhds_within a (set.Ioi a)) (nhds l)) (hfb : filter.tendsto f (nhds_within b (set.Iio b)) (nhds l)) (hff' : ∀ (x : ℝ), x ∈ set.Ioo a b → has_deriv_at f (f' x) x) : ∃ (c : ℝ), ∃ (H : c ∈ set.Ioo a b), f' c = 0 := sorry
theorem exists_deriv_eq_zero' {f : ℝ → ℝ} {a : ℝ} {b : ℝ} (hab : a < b) {l : ℝ} (hfa : filter.tendsto f (nhds_within a (set.Ioi a)) (nhds l)) (hfb : filter.tendsto f (nhds_within b (set.Iio b)) (nhds l)) : ∃ (c : ℝ), ∃ (H : c ∈ set.Ioo a b), deriv f c = 0 := sorry
|
dfbe902dde4b184e283e5425f90b9f2809686528 | 367134ba5a65885e863bdc4507601606690974c1 | /src/algebra/lie/skew_adjoint.lean | 9b31a8b5af9a4517b541d5d80e3eda10a57dc3d7 | [
"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 | 7,203 | lean | /-
Copyright (c) 2020 Oliver Nash. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Oliver Nash
-/
import algebra.lie.matrix
import linear_algebra.bilinear_form
/-!
# Lie algebras of skew-adjoint endomorphisms of a bilinear form
When a module carries a bilinear form, the Lie algebra of endomorphisms of the module contains a
distinguished Lie subalgebra: the skew-adjoint endomorphisms. Such subalgebras are important
because they provide a simple, explicit construction of the so-called classical Lie algebras.
This file defines the Lie subalgebra of skew-adjoint endomorphims cut out by a bilinear form on
a module and proves some basic related results. It also provides the corresponding definitions and
results for the Lie algebra of square matrices.
## Main definitions
* `skew_adjoint_lie_subalgebra`
* `skew_adjoint_lie_subalgebra_equiv`
* `skew_adjoint_matrices_lie_subalgebra`
* `skew_adjoint_matrices_lie_subalgebra_equiv`
## Tags
lie algebra, skew-adjoint, bilinear form
-/
universes u v w w₁
section skew_adjoint_endomorphisms
open bilin_form
variables {R : Type u} {M : Type v} [comm_ring R] [add_comm_group M] [module R M]
variables (B : bilin_form R M)
lemma bilin_form.is_skew_adjoint_bracket (f g : module.End R M)
(hf : f ∈ B.skew_adjoint_submodule) (hg : g ∈ B.skew_adjoint_submodule) :
⁅f, g⁆ ∈ B.skew_adjoint_submodule :=
begin
rw mem_skew_adjoint_submodule at *,
have hfg : is_adjoint_pair B B (f * g) (g * f), { rw ←neg_mul_neg g f, exact hf.mul hg, },
have hgf : is_adjoint_pair B B (g * f) (f * g), { rw ←neg_mul_neg f g, exact hg.mul hf, },
change bilin_form.is_adjoint_pair B B (f * g - g * f) (-(f * g - g * f)), rw neg_sub,
exact hfg.sub hgf,
end
/-- Given an `R`-module `M`, equipped with a bilinear form, the skew-adjoint endomorphisms form a
Lie subalgebra of the Lie algebra of endomorphisms. -/
def skew_adjoint_lie_subalgebra : lie_subalgebra R (module.End R M) :=
{ lie_mem' := B.is_skew_adjoint_bracket, ..B.skew_adjoint_submodule }
variables {N : Type w} [add_comm_group N] [module R N] (e : N ≃ₗ[R] M)
/-- An equivalence of modules with bilinear forms gives equivalence of Lie algebras of skew-adjoint
endomorphisms. -/
def skew_adjoint_lie_subalgebra_equiv :
skew_adjoint_lie_subalgebra (B.comp (↑e : N →ₗ[R] M) ↑e) ≃ₗ⁅R⁆ skew_adjoint_lie_subalgebra B :=
begin
apply lie_equiv.of_subalgebras _ _ e.lie_conj,
ext f,
simp only [lie_subalgebra.mem_coe, submodule.mem_map_equiv, lie_subalgebra.mem_map_submodule,
coe_coe],
exact (bilin_form.is_pair_self_adjoint_equiv (-B) B e f).symm,
end
@[simp] lemma skew_adjoint_lie_subalgebra_equiv_apply
(f : skew_adjoint_lie_subalgebra (B.comp ↑e ↑e)) :
↑(skew_adjoint_lie_subalgebra_equiv B e f) = e.lie_conj f :=
by simp [skew_adjoint_lie_subalgebra_equiv]
@[simp] lemma skew_adjoint_lie_subalgebra_equiv_symm_apply (f : skew_adjoint_lie_subalgebra B) :
↑((skew_adjoint_lie_subalgebra_equiv B e).symm f) = e.symm.lie_conj f :=
by simp [skew_adjoint_lie_subalgebra_equiv]
end skew_adjoint_endomorphisms
section skew_adjoint_matrices
open_locale matrix
variables {R : Type u} {n : Type w} [comm_ring R] [decidable_eq n] [fintype n]
variables (J : matrix n n R)
lemma matrix.lie_transpose (A B : matrix n n R) : ⁅A, B⁆ᵀ = ⁅Bᵀ, Aᵀ⁆ :=
show (A * B - B * A)ᵀ = (Bᵀ * Aᵀ - Aᵀ * Bᵀ), by simp
lemma matrix.is_skew_adjoint_bracket (A B : matrix n n R)
(hA : A ∈ skew_adjoint_matrices_submodule J) (hB : B ∈ skew_adjoint_matrices_submodule J) :
⁅A, B⁆ ∈ skew_adjoint_matrices_submodule J :=
begin
simp only [mem_skew_adjoint_matrices_submodule] at *,
change ⁅A, B⁆ᵀ ⬝ J = J ⬝ -⁅A, B⁆, change Aᵀ ⬝ J = J ⬝ -A at hA, change Bᵀ ⬝ J = J ⬝ -B at hB,
simp only [←matrix.mul_eq_mul] at *,
rw [matrix.lie_transpose, lie_ring.of_associative_ring_bracket,
lie_ring.of_associative_ring_bracket, sub_mul, mul_assoc, mul_assoc, hA, hB, ←mul_assoc,
←mul_assoc, hA, hB],
noncomm_ring,
end
/-- The Lie subalgebra of skew-adjoint square matrices corresponding to a square matrix `J`. -/
def skew_adjoint_matrices_lie_subalgebra : lie_subalgebra R (matrix n n R) :=
{ lie_mem' := J.is_skew_adjoint_bracket, ..(skew_adjoint_matrices_submodule J) }
@[simp] lemma mem_skew_adjoint_matrices_lie_subalgebra (A : matrix n n R) :
A ∈ skew_adjoint_matrices_lie_subalgebra J ↔ A ∈ skew_adjoint_matrices_submodule J :=
iff.rfl
/-- An invertible matrix `P` gives a Lie algebra equivalence between those endomorphisms that are
skew-adjoint with respect to a square matrix `J` and those with respect to `PᵀJP`. -/
noncomputable def skew_adjoint_matrices_lie_subalgebra_equiv (P : matrix n n R) (h : is_unit P) :
skew_adjoint_matrices_lie_subalgebra J ≃ₗ⁅R⁆ skew_adjoint_matrices_lie_subalgebra (Pᵀ ⬝ J ⬝ P) :=
lie_equiv.of_subalgebras _ _ (P.lie_conj h).symm
begin
ext A,
suffices : P.lie_conj h A ∈ skew_adjoint_matrices_submodule J ↔
A ∈ skew_adjoint_matrices_submodule (Pᵀ ⬝ J ⬝ P),
{ simp only [lie_subalgebra.mem_coe, submodule.mem_map_equiv, lie_subalgebra.mem_map_submodule,
coe_coe], exact this, },
simp [matrix.is_skew_adjoint, J.is_adjoint_pair_equiv _ _ P h],
end
lemma skew_adjoint_matrices_lie_subalgebra_equiv_apply
(P : matrix n n R) (h : is_unit P) (A : skew_adjoint_matrices_lie_subalgebra J) :
↑(skew_adjoint_matrices_lie_subalgebra_equiv J P h A) = P⁻¹ ⬝ ↑A ⬝ P :=
by simp [skew_adjoint_matrices_lie_subalgebra_equiv]
/-- An equivalence of matrix algebras commuting with the transpose endomorphisms restricts to an
equivalence of Lie algebras of skew-adjoint matrices. -/
def skew_adjoint_matrices_lie_subalgebra_equiv_transpose {m : Type w} [decidable_eq m] [fintype m]
(e : matrix n n R ≃ₐ[R] matrix m m R) (h : ∀ A, (e A)ᵀ = e (Aᵀ)) :
skew_adjoint_matrices_lie_subalgebra J ≃ₗ⁅R⁆ skew_adjoint_matrices_lie_subalgebra (e J) :=
lie_equiv.of_subalgebras _ _ e.to_lie_equiv
begin
ext A,
suffices : J.is_skew_adjoint (e.symm A) ↔ (e J).is_skew_adjoint A, by simpa [this],
simp [matrix.is_skew_adjoint, matrix.is_adjoint_pair, ← matrix.mul_eq_mul,
← h, ← function.injective.eq_iff e.injective],
end
@[simp] lemma skew_adjoint_matrices_lie_subalgebra_equiv_transpose_apply
{m : Type w} [decidable_eq m] [fintype m]
(e : matrix n n R ≃ₐ[R] matrix m m R) (h : ∀ A, (e A)ᵀ = e (Aᵀ))
(A : skew_adjoint_matrices_lie_subalgebra J) :
(skew_adjoint_matrices_lie_subalgebra_equiv_transpose J e h A : matrix m m R) = e A :=
rfl
lemma mem_skew_adjoint_matrices_lie_subalgebra_unit_smul (u : units R) (J A : matrix n n R) :
A ∈ skew_adjoint_matrices_lie_subalgebra ((u : R) • J) ↔
A ∈ skew_adjoint_matrices_lie_subalgebra J :=
begin
change A ∈ skew_adjoint_matrices_submodule ((u : R) • J) ↔ A ∈ skew_adjoint_matrices_submodule J,
simp only [mem_skew_adjoint_matrices_submodule, matrix.is_skew_adjoint, matrix.is_adjoint_pair],
split; intros h,
{ simpa using congr_arg (λ B, (↑u⁻¹ : R) • B) h, },
{ simp [h], },
end
end skew_adjoint_matrices
|
cf7a20ddb5cd7651665f7ee0cb7f7053e9889daa | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/bin_oct_hex.lean | 413f15261dc08190a45d30bc0f10000926bbd56c | [
"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 | 108 | lean | example : 0xf = 15 :=
rfl
example : 3 = 0b11 :=
rfl
example : 5 = 0b101 :=
rfl
example : 8 = 0o10 :=
rfl
|
e9ca33bfd49a4530b1e551959bc5c66ea5fce569 | ae1e94c332e17c7dc7051ce976d5a9eebe7ab8a5 | /stage0/src/Lean/Data/Trie.lean | c95446cc78348449463d2a6a8d4be10abeff50ac | [
"Apache-2.0"
] | permissive | dupuisf/lean4 | d082d13b01243e1de29ae680eefb476961221eef | 6a39c65bd28eb0e28c3870188f348c8914502718 | refs/heads/master | 1,676,948,755,391 | 1,610,665,114,000 | 1,610,665,114,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 2,755 | lean | /-
Copyright (c) 2018 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Sebastian Ullrich, Leonardo de Moura
Trie for tokenizing the Lean language
-/
import Lean.Data.Format
namespace Lean
namespace Parser
open Std (RBNode RBNode.leaf RBNode.singleton RBNode.find RBNode.insert)
inductive Trie (α : Type) where
| Node : Option α → RBNode Char (fun _ => Trie α) → Trie α
namespace Trie
variables {α : Type}
def empty : Trie α :=
⟨none, RBNode.leaf⟩
instance : EmptyCollection (Trie α) :=
⟨empty⟩
instance : Inhabited (Trie α) where
default := Node none RBNode.leaf
partial def insert (t : Trie α) (s : String) (val : α) : Trie α :=
let rec insertEmpty (i : String.Pos) : Trie α :=
match s.atEnd i with
| true => Trie.Node (some val) RBNode.leaf
| false =>
let c := s.get i
let t := insertEmpty (s.next i)
Trie.Node none (RBNode.singleton c t)
let rec loop
| Trie.Node v m, i =>
match s.atEnd i with
| true => Trie.Node (some val) m -- overrides old value
| false =>
let c := s.get i
let i := s.next i
let t := match RBNode.find Char.lt m c with
| none => insertEmpty i
| some t => loop t i
Trie.Node v (RBNode.insert Char.lt m c t)
loop t 0
partial def find? (t : Trie α) (s : String) : Option α :=
let rec loop
| Trie.Node val m, i =>
match s.atEnd i with
| true => val
| false =>
let c := s.get i
let i := s.next i
match RBNode.find Char.lt m c with
| none => none
| some t => loop t i
loop t 0
private def updtAcc (v : Option α) (i : String.Pos) (acc : String.Pos × Option α) : String.Pos × Option α :=
match v, acc with
| some v, (j, w) => (i, some v) -- we pattern match on `acc` to enable memory reuse
| none, acc => acc
partial def matchPrefix (s : String) (t : Trie α) (i : String.Pos) : String.Pos × Option α :=
let rec loop
| Trie.Node v m, i, acc =>
match s.atEnd i with
| true => updtAcc v i acc
| false =>
let acc := updtAcc v i acc
let c := s.get i
let i := s.next i
match RBNode.find Char.lt m c with
| some t => loop t i acc
| none => acc
loop t i (i, none)
private partial def toStringAux {α : Type} : Trie α → List Format
| Trie.Node val map => map.fold (fun Fs c t =>
format (repr c) :: (Format.group $ Format.nest 2 $ flip Format.joinSep Format.line $ toStringAux t) :: Fs) []
instance {α : Type} : ToString (Trie α) :=
⟨fun t => (flip Format.joinSep Format.line $ toStringAux t).pretty⟩
end Trie
end Parser
end Lean
|
01da3e06d2d82abc79820ff23c95cecec6ea4f63 | 05b503addd423dd68145d68b8cde5cd595d74365 | /src/category_theory/graded_object.lean | d82c711124be5b486e2438de4ad9baebf70daf2a | [
"Apache-2.0"
] | permissive | aestriplex/mathlib | 77513ff2b176d74a3bec114f33b519069788811d | e2fa8b2b1b732d7c25119229e3cdfba8370cb00f | refs/heads/master | 1,621,969,960,692 | 1,586,279,279,000 | 1,586,279,279,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 6,759 | lean | /-
Copyright (c) 2020 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import category_theory.shift
import category_theory.limits.shapes.zero
/-!
# The category of graded objects
For any type `β`, a `β`-graded object over some category `C` is just
a function `β → C` into the objects of `C`.
We define the category structure on these.
We describe the `comap` functors obtained by precomposing with functions `β → γ`.
As a consequence a fixed element (e.g. `1`) in an additive group `β` provides a shift
functor on `β`-graded objects
When `C` has coproducts we construct the `total` functor `graded_object β C ⥤ C`,
show that it is faithful, and deduce that when `C` is concrete so is `graded_object β C`.
-/
open category_theory.limits
namespace category_theory
universes w v u
/-- A type synonym for `β → C`, used for `β`-graded objects in a category `C`. -/
def graded_object (β : Type w) (C : Type u) : Type (max w u) := β → C
-- Satisfying the inhabited linter...
instance inhabited_graded_object (β : Type w) (C : Type u) [inhabited C] :
inhabited (graded_object β C) :=
⟨λ b, inhabited.default C⟩
/--
A type synonym for `β → C`, used for `β`-graded objects in a category `C`
with a shift functor given by translation by `s`.
-/
@[nolint unused_arguments] -- `s` is here to distinguish type synonyms asking for different shifts
abbreviation graded_object_with_shift {β : Type w} [add_comm_group β] (s : β) (C : Type u) : Type (max w u) := graded_object β C
namespace graded_object
variables {C : Type u} [𝒞 : category.{v} C]
include 𝒞
instance category_of_graded_objects (β : Type w) : category.{(max w v)} (graded_object β C) :=
{ hom := λ X Y, Π b : β, X b ⟶ Y b,
id := λ X b, 𝟙 (X b),
comp := λ X Y Z f g b, f b ≫ g b, }
@[simp]
lemma id_apply {β : Type w} (X : graded_object β C) (b : β) :
((𝟙 X) : Π b, X b ⟶ X b) b = 𝟙 (X b) := rfl
@[simp]
lemma comp_apply {β : Type w} {X Y Z : graded_object β C} (f : X ⟶ Y) (g : Y ⟶ Z) (b : β) :
((f ≫ g) : Π b, X b ⟶ Z b) b = f b ≫ g b := rfl
section
variable (C)
/-- Pull back a graded object along a change-of-grading function. -/
@[simps]
def comap {β γ : Type w} (f : β → γ) :
(graded_object γ C) ⥤ (graded_object β C) :=
{ obj := λ X, X ∘ f,
map := λ X Y g b, g (f b) }
/--
The natural isomorphism between
pulling back a grading along the identity function,
and the identity functor. -/
@[simps]
def comap_id (β : Type w) : comap C (id : β → β) ≅ 𝟭 (graded_object β C) :=
{ hom := { app := λ X, 𝟙 X },
inv := { app := λ X, 𝟙 X } }.
/--
The natural isomorphism comparing between
pulling back along two successive functions, and
pulling back along their composition
-/
@[simps]
def comap_comp {β γ δ : Type w} (f : β → γ) (g : γ → δ) : comap C g ⋙ comap C f ≅ comap C (g ∘ f) :=
{ hom := { app := λ X b, 𝟙 (X (g (f b))) },
inv := { app := λ X b, 𝟙 (X (g (f b))) } }
/--
The natural isomorphism comparing between
pulling back along two propositionally equal functions.
-/
@[simps]
def comap_eq {β γ : Type w} {f g : β → γ} (h : f = g) : comap C f ≅ comap C g :=
{ hom := { app := λ X b, eq_to_hom begin dsimp [comap], subst h, end },
inv := { app := λ X b, eq_to_hom begin dsimp [comap], subst h, end }, }
@[simp]
lemma comap_eq_symm {β γ : Type w} {f g : β → γ} (h : f = g) : comap_eq C h.symm = (comap_eq C h).symm :=
by tidy
@[simp]
lemma comap_eq_trans {β γ : Type w} {f g h : β → γ} (k : f = g) (l : g = h) :
comap_eq C (k.trans l) = comap_eq C k ≪≫ comap_eq C l :=
begin
ext X b,
simp,
end
/--
The equivalence between β-graded objects and γ-graded objects,
given an equivalence between β and γ.
-/
@[simps]
def comap_equiv {β γ : Type w} (e : β ≃ γ) :
(graded_object β C) ≌ (graded_object γ C) :=
{ functor := comap C (e.symm : γ → β),
inverse := comap C (e : β → γ),
counit_iso := (comap_comp C _ _).trans (comap_eq C (by { ext, simp } )),
unit_iso := (comap_eq C (by { ext, simp} )).trans (comap_comp _ _ _).symm,
functor_unit_iso_comp' := λ X, begin ext b, dsimp, simp, end, }
end
instance has_shift {β : Type} [add_comm_group β] (s : β) : has_shift.{v} (graded_object_with_shift s C) :=
{ shift := comap_equiv C
{ to_fun := λ b, b-s,
inv_fun := λ b, b+s,
left_inv := λ x, (by simp),
right_inv := λ x, (by simp), } }
instance has_zero_morphisms [has_zero_morphisms.{v} C] (β : Type w) :
has_zero_morphisms.{(max w v)} (graded_object β C) :=
{ has_zero := λ X Y,
{ zero := λ b, 0 } }.
section
local attribute [instance] has_zero_object.has_zero
instance has_zero_object [has_zero_object.{v} C] [has_zero_morphisms.{v} C] (β : Type w) :
has_zero_object.{(max w v)} (graded_object β C) :=
{ zero := λ b, (0 : C),
unique_to := λ X, ⟨⟨λ b, 0⟩, λ f, (by ext)⟩,
unique_from := λ X, ⟨⟨λ b, 0⟩, λ f, (by ext)⟩, }
end
end graded_object
namespace graded_object
-- The universes get a little hairy here, so we restrict the universe level for the grading to 0.
-- Since we're typically interested in grading by ℤ or a finite group, this should be okay.
-- If you're grading by things in higher universes, have fun!
variables (β : Type)
variables (C : Type u) [𝒞 : category.{v} C]
include 𝒞
variables [has_coproducts.{v} C]
/--
The total object of a graded object is the coproduct of the graded components.
-/
def total : graded_object β C ⥤ C :=
{ obj := λ X, ∐ (λ i : ulift.{v} β, X i.down),
map := λ X Y f, limits.sigma.map (λ i, f i.down) }.
variables [decidable_eq β] [has_zero_morphisms.{v} C]
/--
The `total` functor taking a graded object to the coproduct of its graded components is faithful.
To prove this, we need to know that the coprojections into the coproduct are monomorphisms,
which follows from the fact we have zero morphisms and decidable equality for the grading.
-/
instance : faithful.{v} (total.{v u} β C) :=
{ injectivity' := λ X Y f g w,
begin
ext i,
replace w := sigma.ι (λ i : ulift β, X i.down) ⟨i⟩ ≫= w,
erw [colimit.ι_map, colimit.ι_map] at w,
exact mono.right_cancellation _ _ w,
end }
end graded_object
namespace graded_object
variables (β : Type) [decidable_eq β]
variables (C : Type (u+1)) [large_category C] [𝒞 : concrete_category C]
[has_coproducts.{u} C] [has_zero_morphisms.{u} C]
include 𝒞
instance : concrete_category (graded_object β C) :=
{ forget := total β C ⋙ forget C }
instance : has_forget₂ (graded_object β C) C :=
{ forget₂ := total β C }
end graded_object
end category_theory
|
88d5c54eeeac2c5e94893c6eceddaf6ee60fce56 | c3f2fcd060adfa2ca29f924839d2d925e8f2c685 | /tests/lean/run/pquot.lean | 8d9587e7b635fcf782aba27cd94279f565840d32 | [
"Apache-2.0"
] | permissive | respu/lean | 6582d19a2f2838a28ecd2b3c6f81c32d07b5341d | 8c76419c60b63d0d9f7bc04ebb0b99812d0ec654 | refs/heads/master | 1,610,882,451,231 | 1,427,747,084,000 | 1,427,747,429,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 5,415 | lean | import logic.cast data.list data.sigma
-- The (pre-)quotient type kernel extension would add the following constants
-- quot, pquot.mk, pquot.eqv and pquot.rec
-- and a computational rule, which we call pquot.comp here.
-- Note that, these constants do not assume the environment contains =
constant pquot.{l} {A : Type.{l}} (R : A → A → Prop) : Type.{l}
constant pquot.abs {A : Type} (R : A → A → Prop) : A → pquot R
-- pquot.eqv is a way to say R a b → (pquot.abs R a) = (pquot.abs R b) without mentioning equality
constant pquot.eqv {A : Type} (R : A → A → Prop) {a b : A} : R a b → ∀ (P : pquot R → Prop), P (pquot.abs R a) → P (pquot.abs R b)
constant pquot.rec {A : Type} {R : A → A → Prop} {C : pquot R → Type}
(f : Π a, C (pquot.abs R a))
-- sound is essentially saying: ∀ (a b : A) (H : R a b), f a == f b
-- H makes sure we can only define a function on (quot R) if for all a b : A
-- R a b → f a == f b
(sound : ∀ a b, R a b → ∀ P : (Π (q : pquot R), C q → Prop), P (pquot.abs R a) (f a) → P (pquot.abs R b) (f b))
(q : pquot R)
: C q
-- We would also get the following computational rule:
-- pquot.rec R H₁ H₂ (pquot.abs R a) ==> H₁ a
constant pquot.comp {A : Type} {R : A → A → Prop} {C : pquot R → Type}
(f : Π a, C (pquot.abs R a))
(sound : ∀ a b, R a b → ∀ P : (Π (q : pquot R), C q → Prop), P (pquot.abs R a) (f a) → P (pquot.abs R b) (f b))
(a : A)
-- In the implementation this would be a computational rule
: pquot.rec f sound (pquot.abs R a) = f a
-- If the environment contains = and ==, then we can define
definition pquot.eq {A : Type} (R : A → A → Prop) {a b : A} (H : R a b) : pquot.abs R a = pquot.abs R b :=
have aux : ∀ (P : pquot R → Prop), P (pquot.abs R a) → P (pquot.abs R b), from
pquot.eqv R H,
aux (λ x : pquot R, pquot.abs R a = x) rfl
definition pquot.rec_on {A : Type} {R : A → A → Prop} {C : pquot R → Type}
(q : pquot R)
(f : Π a, C (pquot.abs R a))
(sound : ∀ (a b : A), R a b → f a == f b)
: C q :=
pquot.rec f
(λ (a b : A) (H : R a b) (P : Π (q : pquot R), C q → Prop) (Ha : P (pquot.abs R a) (f a)),
have aux₁ : f a == f b, from sound a b H,
have aux₂ : pquot.abs R a = pquot.abs R b, from pquot.eq R H,
have aux₃ : ∀ (c₁ c₂ : C (pquot.abs R a)) (e : c₁ == c₂), P (pquot.abs R a) c₁ → P (pquot.abs R a) c₂, from
λ c₁ c₂ e H, eq.rec_on (heq.to_eq e) H,
have aux₄ : ∀ (c₁ : C (pquot.abs R a)) (c₂ : C (pquot.abs R b)) (e : c₁ == c₂), P (pquot.abs R a) c₁ → P (pquot.abs R b) c₂, from
eq.rec_on aux₂ aux₃,
show P (pquot.abs R b) (f b), from
aux₄ (f a) (f b) aux₁ Ha)
q
definition pquot.lift {A : Type} {R : A → A → Prop} {B : Type}
(f : A → B)
(sound : ∀ (a b : A), R a b → f a = f b)
(q : pquot R)
: B :=
pquot.rec_on q f (λ (a b : A) (H : R a b), heq.of_eq (sound a b H))
theorem pquot.induction_on {A : Type} {R : A → A → Prop} {P : pquot R → Prop}
(q : pquot R)
(f : ∀ a, P (pquot.abs R a))
: P q :=
pquot.rec_on q f (λ (a b : A) (H : R a b),
have aux₁ : pquot.abs R a = pquot.abs R b, from pquot.eq R H,
have aux₂ : P (pquot.abs R a) = P (pquot.abs R b), from congr_arg P aux₁,
have aux₃ : cast aux₂ (f a) = f b, from proof_irrel (cast aux₂ (f a)) (f b),
show f a == f b, from
@cast_to_heq _ _ _ _ aux₂ aux₃)
theorem pquot.abs.surjective {A : Type} {R : A → A → Prop} : ∀ q : pquot R, ∃ x : A, pquot.abs R x = q :=
take q, pquot.induction_on q (take a, exists.intro a rfl)
definition pquot.exact {A : Type} (R : A → A → Prop) :=
∀ a b : A, pquot.abs R a = pquot.abs R b → R a b
-- Definable quotient
structure dquot {A : Type} (R : A → A → Prop) :=
mk :: (rep : pquot R → A)
(complete : ∀a, R (rep (pquot.abs R a)) a)
-- (stable : ∀q, pquot.abs R (rep q) = q)
structure is_equiv {A : Type} (R : A → A → Prop) :=
mk :: (refl : ∀x, R x x)
(symm : ∀{x y}, R x y → R y x)
(trans : ∀{x y z}, R x y → R y z → R x z)
-- Definiable quotients are exact if R is an equivalence relation
theorem quot.exact {A : Type} {R : A → A → Prop} (eqv : is_equiv R) (q : dquot R) : pquot.exact R :=
λ (a b : A) (H : pquot.abs R a = pquot.abs R b),
have H₁ : pquot.abs R a = pquot.abs R a → R (dquot.rep q (pquot.abs R a)) (dquot.rep q (pquot.abs R a)),
from λH, is_equiv.refl eqv _,
have H₂ : pquot.abs R a = pquot.abs R b → R (dquot.rep q (pquot.abs R a)) (dquot.rep q (pquot.abs R b)),
from eq.subst H H₁,
have H₃ : R (dquot.rep q (pquot.abs R a)) (dquot.rep q (pquot.abs R b)),
from H₂ H,
have H₄ : R a (dquot.rep q (pquot.abs R a)), from is_equiv.symm eqv (dquot.complete q a),
have H₅ : R (dquot.rep q (pquot.abs R b)) b, from dquot.complete q b,
is_equiv.trans eqv H₄ (is_equiv.trans eqv H₃ H₅)
|
6a420f62fc337b9417926e2e515679c01c8747cb | cf39355caa609c0f33405126beee2739aa3cb77e | /library/init/meta/has_reflect.lean | 98f15d70b410dbfb79c284aca7b5178f00806041 | [
"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 | 1,797 | lean | /-
Copyright (c) 2017 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Sebastian Ullrich
-/
prelude
import init.meta.expr init.util
universes u v
/-- `has_reflect α` lets you produce an `expr` from an instance of α. That is, it is a function from α to expr such that the expr has type α. -/
@[reducible] meta def has_reflect (α : Sort u) := Π a : α, reflected _ a
meta structure reflected_value (α : Type u) :=
(val : α)
[reflect : reflected _ val]
namespace reflected_value
meta def expr {α : Type u} (v : reflected_value α) : expr := v.reflect
meta def subst {α : Type u} {β : Type v} (f : α → β) [rf : reflected _ f]
(a : reflected_value α) : reflected_value β :=
@mk _ (f a.val) (rf.subst a.reflect)
end reflected_value
section
local attribute [semireducible] reflected
meta instance nat.reflect : has_reflect ℕ
| n := if n = 0 then `(0 : ℕ)
else if n = 1 then `(1 : ℕ)
else if n % 2 = 0 then `(bit0 %%(nat.reflect (n / 2)) : ℕ)
else `(bit1 %%(nat.reflect (n / 2)) : ℕ)
meta instance unsigned.reflect : has_reflect unsigned
| ⟨n, pr⟩ := `(unsigned.of_nat' n)
end
/-! Instances that [derive] depends on. All other basic instances are defined at the end of
derive.lean. -/
meta instance name.reflect : has_reflect name
| name.anonymous := `(name.anonymous)
| (name.mk_string s n) := `(λ n, name.mk_string s n).subst (name.reflect n)
| (name.mk_numeral i n) := `(λ n, name.mk_numeral i n).subst (name.reflect n)
meta instance list.reflect {α : Type} [has_reflect α] [reflected _ α] : has_reflect (list α)
| [] := `([])
| (h::t) := `(λ t, h :: t).subst (list.reflect t)
meta instance punit.reflect : has_reflect punit
| () := `(_)
|
3eff138fef21a9255686af1fe285b3e8eb25a957 | 8cb37a089cdb4af3af9d8bf1002b417e407a8e9e | /library/init/util.lean | 9aa655f18eef6a3181c87da6bcf5ab63bd14143a | [
"Apache-2.0"
] | permissive | kbuzzard/lean | ae3c3db4bb462d750dbf7419b28bafb3ec983ef7 | ed1788fd674bb8991acffc8fca585ec746711928 | refs/heads/master | 1,620,983,366,617 | 1,618,937,600,000 | 1,618,937,600,000 | 359,886,396 | 1 | 0 | Apache-2.0 | 1,618,936,987,000 | 1,618,936,987,000 | null | UTF-8 | Lean | false | false | 1,989 | 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.format
universes u
/-- This function has a native implementation that tracks time. -/
def timeit {α : Type u} (s : string) (f : thunk α) : α :=
f ()
/-- This function has a native implementation that displays the given string in the regular output stream. -/
def trace {α : Type u} (s : string) (f : thunk α) : α :=
f ()
meta def trace_val {α : Type u} [has_to_format α] (f : α) : α :=
trace (to_fmt f).to_string f
/-- This function has a native implementation that shows the VM call stack. -/
def trace_call_stack {α : Type u} (f : thunk α) : α :=
f ()
/-- This function has a native implementation that displays in the given position all trace messages used in f.
The arguments line and col are filled by the elaborator. -/
def scope_trace {α : Type u} {line col: nat} (f : thunk α) : α :=
f ()
/--
This function has a native implementation where
the thunk is interrupted if it takes more than 'max' "heartbeats" to compute it.
The heartbeat is approx. the maximum number of memory allocations (in thousands) performed by 'f ()'.
This is a deterministic way of interrupting long running tasks. -/
meta def try_for {α : Type u} (max : nat) (f : thunk α) : option α :=
some (f ())
/--
This function has a native implementation where
the thunk is interrupted if it takes more than `max` milliseconds to compute it.
This is useful due to the variance in the number of heartbeats used by tactics. -/
meta def try_for_time {α : Type u} (max : ℕ) (f : thunk α) : option α :=
some (f ())
/-- Throws an exception when it is evaluated. -/
meta constant undefined_core {α : Sort u} (message : string) : α
meta def undefined {α : Sort u} : α := undefined_core "undefined"
meta def unchecked_cast {α : Sort u} {β : Sort u} : α → β :=
cast undefined
|
149c19d103079d8f2849b8b0f2041e55a707d3a1 | 4fa118f6209450d4e8d058790e2967337811b2b5 | /src/for_mathlib/topological_field.lean | 2f52bbbe57b6ed192922b7b0cec3f4c4d03aa0bf | [
"Apache-2.0"
] | permissive | leanprover-community/lean-perfectoid-spaces | 16ab697a220ed3669bf76311daa8c466382207f7 | 95a6520ce578b30a80b4c36e36ab2d559a842690 | refs/heads/master | 1,639,557,829,139 | 1,638,797,866,000 | 1,638,797,866,000 | 135,769,296 | 96 | 10 | Apache-2.0 | 1,638,797,866,000 | 1,527,892,754,000 | Lean | UTF-8 | Lean | false | false | 4,910 | lean | import tactic.converter.interactive
import topology.algebra.ring
import for_mathlib.data.set.basic
import for_mathlib.topology
import for_mathlib.rings
open topological_space
namespace topological_space
variables {α : Type*} {β : Type*} {γ : Type*} {δ : Type*}
variables [topological_space β] [topological_space δ]
/-- A product of induced topologies is induced by the product map -/
lemma prod_induced_induced (f : α → β) (g : γ → δ) :
@prod.topological_space _ _ (induced f ‹_›) (induced g ‹_›) = induced (λ p, (f p.1, g p.2)) prod.topological_space :=
begin
letI := induced f ‹_›, letI := induced g ‹_›,
set fxg := (λ p : α × γ, (f p.1, g p.2)),
have key1 : f ∘ (prod.fst : α × γ → α) = (prod.fst : β × δ → β) ∘ fxg, from rfl,
have key2 : g ∘ (prod.snd : α × γ → γ) = (prod.snd : β × δ → δ) ∘ fxg, from rfl,
unfold prod.topological_space, -- product topology is a sup of induced topologies
-- so let's be functorial
conv_lhs {
rw [induced_compose, induced_compose, key1, key2],
congr, rw ← induced_compose, skip, rw ← induced_compose, },
rw induced_inf
end
end topological_space
@[simp]
lemma division_ring.inv_val_eq_inv {α : Type*} [division_ring α] (x : units α) :(x : α)⁻¹ = x.inv :=
begin
rw (show x.inv = (x⁻¹ : units α), from rfl),
rw ←one_div_eq_inv,
symmetry,
apply eq_one_div_of_mul_eq_one,
exact x.mul_inv
end
namespace topological_ring
open topological_space function
variables (R : Type*) [ring R]
lemma units.coe_inj : injective (coe : units R → R) :=
λ x y h, units.ext h
variables [topological_space R]
-- This is not a global instance. Instead we introduced a class `induced_units` asserting
-- something equivalent to this construction holds
def topological_space_units : topological_space (units R) := induced units.val ‹_›
class induced_units (R : Type*) [ring R] [topological_space R] [t : topological_space $ units R] :
Prop :=
(top_eq : t = induced (coe : units R → R) ‹_›)
variables [ring R] [topological_space R] [topological_space $ units R]
lemma induced_units.continuous_coe [induced_units R] : continuous (coe : units R → R) :=
(induced_units.top_eq R).symm ▸ continuous_induced_dom
lemma units_embedding [topological_space $ units R] [induced_units R] :
embedding (units.val : units R → R) :=
{ induced := induced_units.top_eq R,
inj := units.coe_inj _ }
instance top_monoid_units [topological_ring R] [topological_space $ units R] [induced_units R] :
topological_monoid (units R) :=
⟨begin
let mulR := (λ (p : R × R), p.1*p.2),
let mulRx := (λ (p : units R × units R), p.1*p.2),
have key : coe ∘ mulRx = mulR ∘ (λ p, (p.1.val, p.2.val)), from rfl,
rw [continuous_iff_le_induced, induced_units.top_eq R, prod_induced_induced,
induced_compose, key, ← induced_compose],
apply induced_mono,
rw ← continuous_iff_le_induced,
exact continuous_mul,
end⟩
end topological_ring
variables (K : Type*) [division_ring K] [topological_space K]
/-- A topological division ring is a division ring with a topology where all operations are
continuous, including inversion. -/
class topological_division_ring extends topological_ring K : Prop :=
(continuous_inv : ∀ x : K, x ≠ 0 → continuous_at (λ x : K, x⁻¹ : K → K) x)
namespace topological_division_ring
open filter set
/-
In this section, we show that units of a topological division ring endowed with the
induced topology form a topological group. These are not global instances because
one could want another topology on units. To turn on this feature, use:
```lean
local attribute [instance]
topological_ring.topological_space_units topological_division_ring.units_top_group
```
-/
variables [topological_division_ring K]
local attribute [instance] topological_ring.topological_space_units
def induced_units : topological_ring.induced_units K := ⟨rfl⟩
local attribute [instance] induced_units
def units_top_group : topological_group (units K) :=
{ continuous_inv := begin
have : (units.val : units K → K) ∘ (λx, x⁻¹ : units K → units K) = (λx, x⁻¹ : K → K) ∘ (coe : units K → K),
by { ext, apply units.inv_eq_inv },
rw continuous_iff_continuous_at,
intros x,
rw [continuous_at, nhds_induced, nhds_induced, tendsto_iff_comap, comap_comm this],
apply comap_mono,
rw ← tendsto_iff_comap,
convert topological_division_ring.continuous_inv x.val x.ne_zero,
exact x.inv_eq_inv
end ,
..topological_ring.top_monoid_units K}
local attribute [instance] units_top_group
lemma continuous_units_inv : continuous (λ x, x.inv : units K → K) :=
begin
change continuous (coe ∘ (λ x, x⁻¹ : units K → units K)),
refine (topological_ring.induced_units.continuous_coe K).comp _,
exact _root_.continuous_inv,
end
end topological_division_ring
|
04f1deb3982ed4d497a56ac480af8916b58ccb5e | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/order/filter/indicator_function_auto.lean | 3d68db43963ebcf2fe282492b8eee054141103f6 | [] | 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 | 2,815 | lean | /-
Copyright (c) 2020 Zhouhang Zhou. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Zhouhang Zhou, Yury Kudryashov
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.data.indicator_function
import Mathlib.order.filter.at_top_bot
import Mathlib.PostPort
universes u_1 u_3 u_2
namespace Mathlib
/-!
# Indicator function and filters
Properties of indicator functions involving `=ᶠ` and `≤ᶠ`.
## Tags
indicator, characteristic, filter
-/
theorem indicator_eventually_eq {α : Type u_1} {M : Type u_3} [HasZero M] {s : set α} {t : set α}
{f : α → M} {g : α → M} {l : filter α} (hf : filter.eventually_eq (l ⊓ filter.principal s) f g)
(hs : filter.eventually_eq l s t) :
filter.eventually_eq l (set.indicator s f) (set.indicator t g) :=
sorry
theorem indicator_union_eventually_eq {α : Type u_1} {M : Type u_3} [add_monoid M] {s : set α}
{t : set α} {f : α → M} {l : filter α} (h : filter.eventually (fun (a : α) => ¬a ∈ s ∩ t) l) :
filter.eventually_eq l (set.indicator (s ∪ t) f) (set.indicator s f + set.indicator t f) :=
filter.eventually.mono h
fun (a : α) (ha : ¬a ∈ s ∩ t) => set.indicator_union_of_not_mem_inter ha f
theorem indicator_eventually_le_indicator {α : Type u_1} {β : Type u_2} [HasZero β] [preorder β]
{s : set α} {f : α → β} {g : α → β} {l : filter α}
(h : filter.eventually_le (l ⊓ filter.principal s) f g) :
filter.eventually_le l (set.indicator s f) (set.indicator s g) :=
filter.eventually.mono (iff.mp filter.eventually_inf_principal h)
fun (a : α) (h : a ∈ s → f a ≤ g a) => set.indicator_rel_indicator (le_refl 0) h
theorem tendsto_indicator_of_monotone {α : Type u_1} {β : Type u_2} {ι : Type u_3} [preorder ι]
[HasZero β] (s : ι → set α) (hs : monotone s) (f : α → β) (a : α) :
filter.tendsto (fun (i : ι) => set.indicator (s i) f a) filter.at_top
(pure (set.indicator (set.Union fun (i : ι) => s i) f a)) :=
sorry
theorem tendsto_indicator_of_antimono {α : Type u_1} {β : Type u_2} {ι : Type u_3} [preorder ι]
[HasZero β] (s : ι → set α) (hs : ∀ {i j : ι}, i ≤ j → s j ⊆ s i) (f : α → β) (a : α) :
filter.tendsto (fun (i : ι) => set.indicator (s i) f a) filter.at_top
(pure (set.indicator (set.Inter fun (i : ι) => s i) f a)) :=
sorry
theorem tendsto_indicator_bUnion_finset {α : Type u_1} {β : Type u_2} {ι : Type u_3} [HasZero β]
(s : ι → set α) (f : α → β) (a : α) :
filter.tendsto
(fun (n : finset ι) =>
set.indicator (set.Union fun (i : ι) => set.Union fun (H : i ∈ n) => s i) f a)
filter.at_top (pure (set.indicator (set.Union s) f a)) :=
sorry
end Mathlib |
a1e60bb847ec443586343325ed5ca728079ee415 | e94d3f31e48d06d252ee7307fe71efe1d500f274 | /hott/init/funext.hlean | 48e38ce1cee61232fead9ded6ea2eeb6782cc9ec | [
"Apache-2.0"
] | permissive | GallagherCommaJack/lean | e4471240a069d82f97cb361d2bf1a029de3f4256 | 226f8bafeb9baaa5a2ac58000c83d6beb29991e2 | refs/heads/master | 1,610,725,100,482 | 1,459,194,829,000 | 1,459,195,377,000 | 55,377,224 | 0 | 0 | null | 1,459,731,701,000 | 1,459,731,700,000 | null | UTF-8 | Lean | false | false | 10,750 | hlean | /-
Copyright (c) 2014 Jakob von Raumer. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jakob von Raumer, Floris van Doorn
Ported from Coq HoTT
-/
prelude
import .trunc .equiv .ua
open eq is_trunc sigma function is_equiv equiv prod unit prod.ops lift
/-
We now prove that funext follows from a couple of weaker-looking forms
of function extensionality.
This proof is originally due to Voevodsky; it has since been simplified
by Peter Lumsdaine and Michael Shulman.
-/
definition funext.{l k} :=
Π ⦃A : Type.{l}⦄ {P : A → Type.{k}} (f g : Π x, P x), is_equiv (@apd10 A P f g)
-- Naive funext is the simple assertion that pointwise equal functions are equal.
definition naive_funext :=
Π ⦃A : Type⦄ {P : A → Type} (f g : Πx, P x), (f ~ g) → f = g
-- Weak funext says that a product of contractible types is contractible.
definition weak_funext :=
Π ⦃A : Type⦄ (P : A → Type) [H: Πx, is_contr (P x)], is_contr (Πx, P x)
definition weak_funext_of_naive_funext : naive_funext → weak_funext :=
(λ nf A P (Pc : Πx, is_contr (P x)),
let c := λx, center (P x) in
is_contr.mk c (λ f,
have eq' : (λx, center (P x)) ~ f,
from (λx, center_eq (f x)),
have eq : (λx, center (P x)) = f,
from nf A P (λx, center (P x)) f eq',
eq
)
)
/-
The less obvious direction is that weak_funext implies funext
(and hence all three are logically equivalent). The point is that under weak
funext, the space of "pointwise homotopies" has the same universal property as
the space of paths.
-/
section
universe variables l k
parameters [wf : weak_funext.{l k}] {A : Type.{l}} {B : A → Type.{k}} (f : Π x, B x)
definition is_contr_sigma_homotopy : is_contr (Σ (g : Π x, B x), f ~ g) :=
is_contr.mk (sigma.mk f (homotopy.refl f))
(λ dp, sigma.rec_on dp
(λ (g : Π x, B x) (h : f ~ g),
let r := λ (k : Π x, Σ y, f x = y),
@sigma.mk _ (λg, f ~ g)
(λx, pr1 (k x)) (λx, pr2 (k x)) in
let s := λ g h x, @sigma.mk _ (λy, f x = y) (g x) (h x) in
have t1 : Πx, is_contr (Σ y, f x = y),
from (λx, !is_contr_sigma_eq),
have t2 : is_contr (Πx, Σ y, f x = y),
from !wf,
have t3 : (λ x, @sigma.mk _ (λ y, f x = y) (f x) idp) = s g h,
from @eq_of_is_contr (Π x, Σ y, f x = y) t2 _ _,
have t4 : r (λ x, sigma.mk (f x) idp) = r (s g h),
from ap r t3,
have endt : sigma.mk f (homotopy.refl f) = sigma.mk g h,
from t4,
endt
)
)
local attribute is_contr_sigma_homotopy [instance]
parameters (Q : Π g (h : f ~ g), Type) (d : Q f (homotopy.refl f))
definition homotopy_ind (g : Πx, B x) (h : f ~ g) : Q g h :=
@transport _ (λ gh, Q (pr1 gh) (pr2 gh)) (sigma.mk f (homotopy.refl f)) (sigma.mk g h)
(@eq_of_is_contr _ is_contr_sigma_homotopy _ _) d
local attribute weak_funext [reducible]
local attribute homotopy_ind [reducible]
definition homotopy_ind_comp : homotopy_ind f (homotopy.refl f) = d :=
(@prop_eq_of_is_contr _ _ _ _ !eq_of_is_contr idp)⁻¹ ▸ idp
end
/- Now the proof is fairly easy; we can just use the same induction principle on both sides. -/
section
universe variables l k
local attribute weak_funext [reducible]
theorem funext_of_weak_funext (wf : weak_funext.{l k}) : funext.{l k} :=
λ A B f g,
let eq_to_f := (λ g' x, f = g') in
let sim2path := homotopy_ind f eq_to_f idp in
have t1 : sim2path f (homotopy.refl f) = idp,
proof homotopy_ind_comp f eq_to_f idp qed,
have t2 : apd10 (sim2path f (homotopy.refl f)) = (homotopy.refl f),
proof ap apd10 t1 qed,
have left_inv : apd10 ∘ (sim2path g) ~ id,
proof (homotopy_ind f (λ g' x, apd10 (sim2path g' x) = x) t2) g qed,
have right_inv : (sim2path g) ∘ apd10 ~ id,
from (λ h, eq.rec_on h (homotopy_ind_comp f _ idp)),
is_equiv.adjointify apd10 (sim2path g) left_inv right_inv
definition funext_from_naive_funext : naive_funext → funext :=
compose funext_of_weak_funext weak_funext_of_naive_funext
end
section
universe variables l
private theorem ua_isequiv_postcompose {A B : Type.{l}} {C : Type}
{w : A → B} [H0 : is_equiv w] : is_equiv (@compose C A B w) :=
let w' := equiv.mk w H0 in
let eqinv : A = B := ((@is_equiv.inv _ _ _ (univalence A B)) w') in
let eq' := equiv_of_eq eqinv in
is_equiv.adjointify (@compose C A B w)
(@compose C B A (is_equiv.inv w))
(λ (x : C → B),
have eqretr : eq' = w',
from (@right_inv _ _ (@equiv_of_eq A B) (univalence A B) w'),
have invs_eq : (to_fun eq')⁻¹ = (to_fun w')⁻¹,
from inv_eq eq' w' eqretr,
have eqfin : (to_fun eq') ∘ ((to_fun eq')⁻¹ ∘ x) = x,
from (λ p,
(@eq.rec_on Type.{l} A
(λ B' p', Π (x' : C → B'), (to_fun (equiv_of_eq p'))
∘ ((to_fun (equiv_of_eq p'))⁻¹ ∘ x') = x')
B p (λ x', idp))
) eqinv x,
have eqfin' : (to_fun w') ∘ ((to_fun eq')⁻¹ ∘ x) = x,
from eqretr ▸ eqfin,
have eqfin'' : (to_fun w') ∘ ((to_fun w')⁻¹ ∘ x) = x,
from invs_eq ▸ eqfin',
eqfin''
)
(λ (x : C → A),
have eqretr : eq' = w',
from (@right_inv _ _ (@equiv_of_eq A B) (univalence A B) w'),
have invs_eq : (to_fun eq')⁻¹ = (to_fun w')⁻¹,
from inv_eq eq' w' eqretr,
have eqfin : (to_fun eq')⁻¹ ∘ ((to_fun eq') ∘ x) = x,
from (λ p, eq.rec_on p idp) eqinv,
have eqfin' : (to_fun eq')⁻¹ ∘ ((to_fun w') ∘ x) = x,
from eqretr ▸ eqfin,
have eqfin'' : (to_fun w')⁻¹ ∘ ((to_fun w') ∘ x) = x,
from invs_eq ▸ eqfin',
eqfin''
)
-- We are ready to prove functional extensionality,
-- starting with the naive non-dependent version.
private definition diagonal [reducible] (B : Type) : Type
:= Σ xy : B × B, pr₁ xy = pr₂ xy
private definition isequiv_src_compose {A B : Type}
: @is_equiv (A → diagonal B)
(A → B)
(compose (pr₁ ∘ pr1)) :=
@ua_isequiv_postcompose _ _ _ (pr₁ ∘ pr1)
(is_equiv.adjointify (pr₁ ∘ pr1)
(λ x, sigma.mk (x , x) idp) (λx, idp)
(λ x, sigma.rec_on x
(λ xy, prod.rec_on xy
(λ b c p, eq.rec_on p idp))))
private definition isequiv_tgt_compose {A B : Type}
: is_equiv (compose (pr₂ ∘ pr1) : (A → diagonal B) → (A → B)) :=
begin
refine @ua_isequiv_postcompose _ _ _ (pr2 ∘ pr1) _,
fapply adjointify,
{ intro b, exact ⟨(b, b), idp⟩},
{ intro b, reflexivity},
{ intro a, induction a with q p, induction q, esimp at *, induction p, reflexivity}
end
theorem nondep_funext_from_ua {A : Type} {B : Type}
: Π {f g : A → B}, f ~ g → f = g :=
(λ (f g : A → B) (p : f ~ g),
let d := λ (x : A), @sigma.mk (B × B) (λ (xy : B × B), xy.1 = xy.2) (f x , f x) (eq.refl (f x, f x).1) in
let e := λ (x : A), @sigma.mk (B × B) (λ (xy : B × B), xy.1 = xy.2) (f x , g x) (p x) in
let precomp1 := compose (pr₁ ∘ sigma.pr1) in
have equiv1 : is_equiv precomp1,
from @isequiv_src_compose A B,
have equiv2 : Π (x y : A → diagonal B), is_equiv (ap precomp1),
from is_equiv.is_equiv_ap precomp1,
have H' : Π (x y : A → diagonal B), pr₁ ∘ pr1 ∘ x = pr₁ ∘ pr1 ∘ y → x = y,
from (λ x y, is_equiv.inv (ap precomp1)),
have eq2 : pr₁ ∘ pr1 ∘ d = pr₁ ∘ pr1 ∘ e,
from idp,
have eq0 : d = e,
from H' d e eq2,
have eq1 : (pr₂ ∘ pr1) ∘ d = (pr₂ ∘ pr1) ∘ e,
from ap _ eq0,
eq1
)
end
-- Now we use this to prove weak funext, which as we know
-- implies (with dependent eta) also the strong dependent funext.
theorem weak_funext_of_ua : weak_funext :=
(λ (A : Type) (P : A → Type) allcontr,
let U := (λ (x : A), lift unit) in
have pequiv : Π (x : A), P x ≃ unit,
from (λ x, @equiv_unit_of_is_contr (P x) (allcontr x)),
have psim : Π (x : A), P x = U x,
from (λ x, eq_of_equiv_lift (pequiv x)),
have p : P = U,
from @nondep_funext_from_ua A Type P U psim,
have tU' : is_contr (A → lift unit),
from is_contr.mk (λ x, up ⋆)
(λ f, nondep_funext_from_ua (λa, by induction (f a) with u;induction u;reflexivity)),
have tU : is_contr (Π x, U x),
from tU',
have tlast : is_contr (Πx, P x),
from p⁻¹ ▸ tU,
tlast)
-- we have proven function extensionality from the univalence axiom
definition funext_of_ua : funext :=
funext_of_weak_funext (@weak_funext_of_ua)
/-
We still take funext as an axiom, so that when you write "print axioms foo", you can see whether
it uses only function extensionality, and not also univalence.
-/
axiom function_extensionality : funext
variables {A : Type} {P : A → Type} {f g : Π x, P x}
namespace funext
theorem is_equiv_apd [instance] (f g : Π x, P x) : is_equiv (@apd10 A P f g) :=
function_extensionality f g
end funext
open funext
definition eq_equiv_homotopy : (f = g) ≃ (f ~ g) :=
equiv.mk apd10 _
definition eq_of_homotopy [reducible] : f ~ g → f = g :=
(@apd10 A P f g)⁻¹
definition apd10_eq_of_homotopy (p : f ~ g) : apd10 (eq_of_homotopy p) = p :=
right_inv apd10 p
definition eq_of_homotopy_apd10 (p : f = g) : eq_of_homotopy (apd10 p) = p :=
left_inv apd10 p
definition eq_of_homotopy_idp (f : Π x, P x) : eq_of_homotopy (λx : A, idpath (f x)) = idpath f :=
is_equiv.left_inv apd10 idp
definition naive_funext_of_ua : naive_funext :=
λ A P f g h, eq_of_homotopy h
protected definition homotopy.rec_on [recursor] {Q : (f ~ g) → Type} (p : f ~ g)
(H : Π(q : f = g), Q (apd10 q)) : Q p :=
right_inv apd10 p ▸ H (eq_of_homotopy p)
protected definition homotopy.rec_on_idp [recursor] {Q : Π{g}, (f ~ g) → Type} {g : Π x, P x} (p : f ~ g) (H : Q (homotopy.refl f)) : Q p :=
homotopy.rec_on p (λq, eq.rec_on q H)
definition eq_of_homotopy_inv {f g : Π x, P x} (H : f ~ g)
: eq_of_homotopy (λx, (H x)⁻¹) = (eq_of_homotopy H)⁻¹ :=
begin
apply homotopy.rec_on_idp H,
rewrite [+eq_of_homotopy_idp]
end
definition eq_of_homotopy_con {f g h : Π x, P x} (H1 : f ~ g) (H2 : g ~ h)
: eq_of_homotopy (λx, H1 x ⬝ H2 x) = eq_of_homotopy H1 ⬝ eq_of_homotopy H2 :=
begin
apply homotopy.rec_on_idp H1,
apply homotopy.rec_on_idp H2,
rewrite [+eq_of_homotopy_idp]
end
|
1d7b768d5bf41a41a6f0c806cfe980a4973df002 | 1b8f093752ba748c5ca0083afef2959aaa7dace5 | /src/category_theory/coyoneda.lean | 45d0c19fba2fd3ce9fd656cb84680cd9b13c00c8 | [] | no_license | khoek/lean-category-theory | 7ec4cda9cc64a5a4ffeb84712ac7d020dbbba386 | 63dcb598e9270a3e8b56d1769eb4f825a177cd95 | refs/heads/master | 1,585,251,725,759 | 1,539,344,445,000 | 1,539,344,445,000 | 145,281,070 | 0 | 0 | null | 1,534,662,376,000 | 1,534,662,376,000 | null | UTF-8 | Lean | false | false | 739 | lean | import category_theory.yoneda
import category_theory.tactics.obviously
universes u₁ v₁
open category_theory
variables (C : Type u₁) [𝒞 : category.{u₁ v₁} C]
include 𝒞
def coyoneda : (Cᵒᵖ) ⥤ (C ⥤ (Type v₁)) :=
{ obj := λ X : C, { obj := λ Y, X ⟶ Y,
map' := λ Y Y' f g, g ≫ f },
map' := λ X X' f, { app := λ Y g, f ≫ g } }
@[simp] lemma coyoneda_obj_obj (X Y : C) : ((coyoneda C) X) Y = (X ⟶ Y) := rfl
@[simp] lemma coyoneda_obj_map (X : C) {Y Y' : C} (f : Y ⟶ Y') : ((coyoneda C) X).map f = λ g, g ≫ f := rfl
@[simp] lemma coyoneda_map_app {X X' : C} (f : X ⟶ X') (Y : C) : ((coyoneda C).map f) Y = λ g, f ≫ g := rfl
-- Does anyone need the coyoneda lemma as well?
|
7a681aaada391b8c3d29fcf7dc42ddfc509c3a8b | 6afa22d5eee6e9a56b6a2f1210eca8f7a1067466 | /library/data/buffer/parser.lean | 24b7221e09b4e2b93c02c47b27617169862c20d7 | [
"Apache-2.0"
] | permissive | giordano/lean | 72a1fabfeb2f1ccfd38673e2719a719cd6ffbb40 | 56f8877f1efa22215aca0b82f1c0ce2ff975b9c3 | refs/heads/master | 1,663,091,511,168 | 1,590,688,082,000 | 1,590,688,082,000 | 268,183,678 | 0 | 0 | Apache-2.0 | 1,590,885,425,000 | 1,590,885,424,000 | null | UTF-8 | Lean | false | false | 7,599 | lean | /-
Copyright (c) 2017 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Gabriel Ebner
-/
import data.buffer data.dlist
inductive parse_result (α : Type)
| done (pos : ℕ) (result : α) : parse_result
| fail (pos : ℕ) (expected : dlist string) : parse_result
/-- The parser monad. If you are familiar with the Parsec library in Haskell, you will understand this. -/
def parser (α : Type) :=
∀ (input : char_buffer) (start : ℕ), parse_result α
namespace parser
variables {α β γ : Type}
protected def bind (p : parser α) (f : α → parser β) : parser β :=
λ input pos, match p input pos with
| parse_result.done pos a := f a input pos
| parse_result.fail pos expected := parse_result.fail pos expected
end
protected def pure (a : α) : parser α :=
λ input pos, parse_result.done pos a
private lemma parser.id_map (p : parser α) : parser.bind p parser.pure = p :=
begin
apply funext, intro input,
apply funext, intro pos,
dunfold parser.bind,
cases (p input pos); exact rfl
end
private lemma parser.bind_assoc (p : parser α) (q : α → parser β) (r : β → parser γ) :
parser.bind (parser.bind p q) r = parser.bind p (λ a, parser.bind (q a) r) :=
begin
apply funext, intro input,
apply funext, intro pos,
dunfold parser.bind,
cases (p input pos); try {dunfold bind},
cases (q result input pos_1); try {dunfold bind},
all_goals {refl}
end
protected def fail (msg : string) : parser α :=
λ _ pos, parse_result.fail pos (dlist.singleton msg)
instance : monad parser :=
{ pure := @parser.pure, bind := @parser.bind }
instance : is_lawful_monad parser :=
{ id_map := @parser.id_map,
pure_bind := λ _ _ _ _, rfl,
bind_assoc := @parser.bind_assoc }
instance : monad_fail parser :=
{ fail := @parser.fail, ..parser.monad }
protected def failure : parser α :=
λ _ pos, parse_result.fail pos dlist.empty
protected def orelse (p q : parser α) : parser α :=
λ input pos, match p input pos with
| parse_result.fail pos₁ expected₁ :=
if pos₁ ≠ pos then parse_result.fail pos₁ expected₁ else
match q input pos with
| parse_result.fail pos₂ expected₂ :=
if pos₁ < pos₂ then
parse_result.fail pos₁ expected₁
else if pos₂ < pos₁ then
parse_result.fail pos₂ expected₂
else -- pos₁ = pos₂
parse_result.fail pos₁ (expected₁ ++ expected₂)
| ok := ok
end
| ok := ok
end
instance : alternative parser :=
{ failure := @parser.failure,
orelse := @parser.orelse }
instance : inhabited (parser α) :=
⟨parser.failure⟩
/-- Overrides the expected token name, and does not consume input on failure. -/
def decorate_errors (msgs : thunk (list string)) (p : parser α) : parser α :=
λ input pos, match p input pos with
| parse_result.fail _ expected :=
parse_result.fail pos (dlist.lazy_of_list (msgs ()))
| ok := ok
end
/-- Overrides the expected token name, and does not consume input on failure. -/
def decorate_error (msg : thunk string) (p : parser α) : parser α :=
decorate_errors [msg ()] p
/-- Matches a single character satisfying the given predicate. -/
def sat (p : char → Prop) [decidable_pred p] : parser char :=
λ input pos,
if h : pos < input.size then
let c := input.read ⟨pos, h⟩ in
if p c then
parse_result.done (pos+1) $ input.read ⟨pos, h⟩
else
parse_result.fail pos dlist.empty
else
parse_result.fail pos dlist.empty
/-- Matches the empty word. -/
def eps : parser unit := return ()
/-- Matches the given character. -/
def ch (c : char) : parser unit :=
decorate_error c.to_string $ sat (= c) >> eps
/-- Matches a whole char_buffer. Does not consume input in case of failure. -/
def char_buf (s : char_buffer) : parser unit :=
decorate_error s.to_string $ s.to_list.mmap' ch
/-- Matches one out of a list of characters. -/
def one_of (cs : list char) : parser char :=
decorate_errors (do c ← cs, return c.to_string) $
sat (∈ cs)
def one_of' (cs : list char) : parser unit :=
one_of cs >> eps
/-- Matches a string. Does not consume input in case of failure. -/
def str (s : string) : parser unit :=
decorate_error s $ s.to_list.mmap' ch
/-- Number of remaining input characters. -/
def remaining : parser ℕ :=
λ input pos, parse_result.done pos (input.size - pos)
/-- Matches the end of the input. -/
def eof : parser unit :=
decorate_error "<end-of-file>" $
do rem ← remaining, guard $ rem = 0
def foldr_core (f : α → β → β) (p : parser α) (b : β) : ∀ (reps : ℕ), parser β
| 0 := failure
| (reps+1) := (do x ← p, xs ← foldr_core reps, return (f x xs)) <|> return b
/-- Matches zero or more occurrences of `p`, and folds the result. -/
def foldr (f : α → β → β) (p : parser α) (b : β) : parser β :=
λ input pos, foldr_core f p b (input.size - pos + 1) input pos
def foldl_core (f : α → β → α) : ∀ (a : α) (p : parser β) (reps : ℕ), parser α
| a p 0 := failure
| a p (reps+1) := (do x ← p, foldl_core (f a x) p reps) <|> return a
/-- Matches zero or more occurrences of `p`, and folds the result. -/
def foldl (f : α → β → α) (a : α) (p : parser β) : parser α :=
λ input pos, foldl_core f a p (input.size - pos + 1) input pos
/-- Matches zero or more occurrences of `p`. -/
def many (p : parser α) : parser (list α) :=
foldr list.cons p []
def many_char (p : parser char) : parser string :=
list.as_string <$> many p
/-- Matches zero or more occurrences of `p`. -/
def many' (p : parser α) : parser unit :=
many p >> eps
/-- Matches one or more occurrences of `p`. -/
def many1 (p : parser α) : parser (list α) :=
list.cons <$> p <*> many p
/-- Matches one or more occurences of the char parser `p` and implodes them into a string. -/
def many_char1 (p : parser char) : parser string :=
list.as_string <$> many1 p
/-- Matches one or more occurrences of `p`, separated by `sep`. -/
def sep_by1 (sep : parser unit) (p : parser α) : parser (list α) :=
list.cons <$> p <*> many (sep >> p)
/-- Matches zero or more occurrences of `p`, separated by `sep`. -/
def sep_by (sep : parser unit) (p : parser α) : parser (list α) :=
sep_by1 sep p <|> return []
def fix_core (F : parser α → parser α) : ∀ (max_depth : ℕ), parser α
| 0 := failure
| (max_depth+1) := F (fix_core max_depth)
/-- Fixpoint combinator satisfying `fix F = F (fix F)`. -/
def fix (F : parser α → parser α) : parser α :=
λ input pos, fix_core F (input.size - pos + 1) input pos
private def make_monospaced : char → char
| '\n' := ' '
| '\t' := ' '
| '\x0d' := ' '
| c := c
def mk_error_msg (input : char_buffer) (pos : ℕ) (expected : dlist string) : char_buffer :=
let left_ctx := (input.take pos).take_right 10,
right_ctx := (input.drop pos).take 10 in
left_ctx.map make_monospaced ++ right_ctx.map make_monospaced ++ "\n".to_char_buffer ++
left_ctx.map (λ _, ' ') ++ "^\n".to_char_buffer ++
"\n".to_char_buffer ++
"expected: ".to_char_buffer
++ string.to_char_buffer (" | ".intercalate expected.to_list)
++ "\n".to_char_buffer
/-- Runs a parser on the given input. The parser needs to match the complete input. -/
def run (p : parser α) (input : char_buffer) : sum string α :=
match (p <* eof) input 0 with
| parse_result.done pos res := sum.inr res
| parse_result.fail pos expected :=
sum.inl $ buffer.to_string $ mk_error_msg input pos expected
end
/-- Runs a parser on the given input. The parser needs to match the complete input. -/
def run_string (p : parser α) (input : string) : sum string α :=
run p input.to_char_buffer
end parser
|
45a24b6e40ae3eb186cd3e456ee7a8d99be05032 | d1a52c3f208fa42c41df8278c3d280f075eb020c | /stage0/src/Init/Meta.lean | 020723340d858f576d1cb44ec501feb29321cc9c | [
"Apache-2.0",
"LLVM-exception",
"NCSA",
"LGPL-3.0-only",
"LicenseRef-scancode-inner-net-2.0",
"BSD-3-Clause",
"LGPL-2.0-or-later",
"Spencer-94",
"LGPL-2.1-or-later",
"HPND",
"LicenseRef-scancode-pcre",
"ISC",
"LGPL-2.1-only",
"LicenseRef-scancode-other-permissive",
"SunPro",
"CMU-Mach"... | permissive | cipher1024/lean4 | 6e1f98bb58e7a92b28f5364eb38a14c8d0aae393 | 69114d3b50806264ef35b57394391c3e738a9822 | refs/heads/master | 1,642,227,983,603 | 1,642,011,696,000 | 1,642,011,696,000 | 228,607,691 | 0 | 0 | Apache-2.0 | 1,576,584,269,000 | 1,576,584,268,000 | null | UTF-8 | Lean | false | false | 34,980 | 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 and Sebastian Ullrich
Additional goodies for writing macros
-/
prelude
import Init.Data.Array.Basic
namespace Lean
@[extern c inline "lean_box(LEAN_VERSION_MAJOR)"]
private constant version.getMajor (u : Unit) : Nat
def version.major : Nat := version.getMajor ()
@[extern c inline "lean_box(LEAN_VERSION_MINOR)"]
private constant version.getMinor (u : Unit) : Nat
def version.minor : Nat := version.getMinor ()
@[extern c inline "lean_box(LEAN_VERSION_PATCH)"]
private constant version.getPatch (u : Unit) : Nat
def version.patch : Nat := version.getPatch ()
@[extern "lean_get_githash"]
constant getGithash (u : Unit) : String
def githash : String := getGithash ()
@[extern c inline "LEAN_VERSION_IS_RELEASE"]
constant version.getIsRelease (u : Unit) : Bool
def version.isRelease : Bool := version.getIsRelease ()
/-- Additional version description like "nightly-2018-03-11" -/
@[extern c inline "lean_mk_string(LEAN_SPECIAL_VERSION_DESC)"]
constant version.getSpecialDesc (u : Unit) : String
def version.specialDesc : String := version.getSpecialDesc ()
def versionStringCore :=
toString version.major ++ "." ++ toString Lean.version.minor ++ "." ++ toString Lean.version.patch
def versionString :=
if version.isRelease then
versionStringCore
else if version.specialDesc ≠ "" then
version.specialDesc
else
"master (" ++ versionStringCore ++ ", commit " ++ getGithash () ++ ")"
/- Valid identifier names -/
def isGreek (c : Char) : Bool :=
0x391 ≤ c.val && c.val ≤ 0x3dd
def isLetterLike (c : Char) : Bool :=
(0x3b1 ≤ c.val && c.val ≤ 0x3c9 && c.val ≠ 0x3bb) || -- Lower greek, but lambda
(0x391 ≤ c.val && c.val ≤ 0x3A9 && c.val ≠ 0x3A0 && c.val ≠ 0x3A3) || -- Upper greek, but Pi and Sigma
(0x3ca ≤ c.val && c.val ≤ 0x3fb) || -- Coptic letters
(0x1f00 ≤ c.val && c.val ≤ 0x1ffe) || -- Polytonic Greek Extended Character Set
(0x2100 ≤ c.val && c.val ≤ 0x214f) || -- Letter like block
(0x1d49c ≤ c.val && c.val ≤ 0x1d59f) -- Latin letters, Script, Double-struck, Fractur
def isNumericSubscript (c : Char) : Bool :=
0x2080 ≤ c.val && c.val ≤ 0x2089
def isSubScriptAlnum (c : Char) : Bool :=
isNumericSubscript c ||
(0x2090 ≤ c.val && c.val ≤ 0x209c) ||
(0x1d62 ≤ c.val && c.val ≤ 0x1d6a)
def isIdFirst (c : Char) : Bool :=
c.isAlpha || c = '_' || isLetterLike c
def isIdRest (c : Char) : Bool :=
c.isAlphanum || c = '_' || c = '\'' || c == '!' || c == '?' || isLetterLike c || isSubScriptAlnum c
def idBeginEscape := '«'
def idEndEscape := '»'
def isIdBeginEscape (c : Char) : Bool := c = idBeginEscape
def isIdEndEscape (c : Char) : Bool := c = idEndEscape
namespace Name
def getRoot : Name → Name
| anonymous => anonymous
| n@(str anonymous _ _) => n
| n@(num anonymous _ _) => n
| str n _ _ => getRoot n
| num n _ _ => getRoot n
@[export lean_is_inaccessible_user_name]
def isInaccessibleUserName : Name → Bool
| Name.str _ s _ => s.contains '✝' || s == "_inaccessible"
| Name.num p idx _ => isInaccessibleUserName p
| _ => false
def escapePart (s : String) : Option String :=
if s.length > 0 && isIdFirst s[0] && (s.toSubstring.drop 1).all isIdRest then s
else if s.any isIdEndEscape then none
else some <| idBeginEscape.toString ++ s ++ idEndEscape.toString
-- NOTE: does not roundtrip even with `escape = true` if name is anonymous or contains numeric part or `idEndEscape`
variable (sep : String) (escape : Bool)
def toStringWithSep : Name → String
| anonymous => "[anonymous]"
| str anonymous s _ => maybeEscape s
| num anonymous v _ => toString v
| str n s _ => toStringWithSep n ++ sep ++ maybeEscape s
| num n v _ => toStringWithSep n ++ sep ++ Nat.repr v
where
maybeEscape s := if escape then escapePart s |>.getD s else s
protected def toString (n : Name) (escape := true) : String :=
-- never escape "prettified" inaccessible names or macro scopes or pseudo-syntax introduced by the delaborator
toStringWithSep "." (escape && !n.isInaccessibleUserName && !n.hasMacroScopes && !maybePseudoSyntax) n
where
maybePseudoSyntax :=
if let Name.str _ s _ := n.getRoot then
-- could be pseudo-syntax for loose bvar or universe mvar, output as is
"#".isPrefixOf s || "?".isPrefixOf s
else
false
instance : ToString Name where
toString n := n.toString
private def hasNum : Name → Bool
| anonymous => false
| num .. => true
| str p .. => hasNum p
protected def reprPrec (n : Name) (prec : Nat) : Std.Format :=
match n with
| anonymous => Std.Format.text "Lean.Name.anonymous"
| num p i _ => Repr.addAppParen ("Lean.Name.mkNum " ++ Name.reprPrec p max_prec ++ " " ++ repr i) prec
| str p s _ =>
if p.hasNum then
Repr.addAppParen ("Lean.Name.mkStr " ++ Name.reprPrec p max_prec ++ " " ++ repr s) prec
else
Std.Format.text "`" ++ n.toString
instance : Repr Name where
reprPrec := Name.reprPrec
deriving instance Repr for Syntax
def capitalize : Name → Name
| Name.str p s _ => Name.mkStr p s.capitalize
| n => n
def replacePrefix : Name → Name → Name → Name
| anonymous, anonymous, newP => newP
| anonymous, _, _ => anonymous
| n@(str p s _), queryP, newP => if n == queryP then newP else Name.mkStr (p.replacePrefix queryP newP) s
| n@(num p s _), queryP, newP => if n == queryP then newP else Name.mkNum (p.replacePrefix queryP newP) s
/-- Remove macros scopes, apply `f`, and put them back -/
@[inline] def modifyBase (n : Name) (f : Name → Name) : Name :=
if n.hasMacroScopes then
let view := extractMacroScopes n
{ view with name := f view.name }.review
else
f n
@[export lean_name_append_after]
def appendAfter (n : Name) (suffix : String) : Name :=
n.modifyBase fun
| str p s _ => Name.mkStr p (s ++ suffix)
| n => Name.mkStr n suffix
@[export lean_name_append_index_after]
def appendIndexAfter (n : Name) (idx : Nat) : Name :=
n.modifyBase fun
| str p s _ => Name.mkStr p (s ++ "_" ++ toString idx)
| n => Name.mkStr n ("_" ++ toString idx)
@[export lean_name_append_before]
def appendBefore (n : Name) (pre : String) : Name :=
n.modifyBase fun
| anonymous => Name.mkStr anonymous pre
| str p s _ => Name.mkStr p (pre ++ s)
| num p n _ => Name.mkNum (Name.mkStr p pre) n
end Name
structure NameGenerator where
namePrefix : Name := `_uniq
idx : Nat := 1
deriving Inhabited
namespace NameGenerator
@[inline] def curr (g : NameGenerator) : Name :=
Name.mkNum g.namePrefix g.idx
@[inline] def next (g : NameGenerator) : NameGenerator :=
{ g with idx := g.idx + 1 }
@[inline] def mkChild (g : NameGenerator) : NameGenerator × NameGenerator :=
({ namePrefix := Name.mkNum g.namePrefix g.idx, idx := 1 },
{ g with idx := g.idx + 1 })
end NameGenerator
class MonadNameGenerator (m : Type → Type) where
getNGen : m NameGenerator
setNGen : NameGenerator → m Unit
export MonadNameGenerator (getNGen setNGen)
def mkFreshId {m : Type → Type} [Monad m] [MonadNameGenerator m] : m Name := do
let ngen ← getNGen
let r := ngen.curr
setNGen ngen.next
pure r
instance monadNameGeneratorLift (m n : Type → Type) [MonadLift m n] [MonadNameGenerator m] : MonadNameGenerator n := {
getNGen := liftM (getNGen : m _),
setNGen := fun ngen => liftM (setNGen ngen : m _)
}
namespace Syntax
partial def structEq : Syntax → Syntax → Bool
| Syntax.missing, Syntax.missing => true
| Syntax.node _ k args, Syntax.node _ k' args' => k == k' && args.isEqv args' structEq
| Syntax.atom _ val, Syntax.atom _ val' => val == val'
| Syntax.ident _ rawVal val preresolved, Syntax.ident _ rawVal' val' preresolved' => rawVal == rawVal' && val == val' && preresolved == preresolved'
| _, _ => false
instance : BEq Lean.Syntax := ⟨structEq⟩
partial def getTailInfo? : Syntax → Option SourceInfo
| atom info _ => info
| ident info .. => info
| node SourceInfo.none _ args =>
args.findSomeRev? getTailInfo?
| node info _ args => info
| _ => none
def getTailInfo (stx : Syntax) : SourceInfo :=
stx.getTailInfo?.getD SourceInfo.none
def getTrailingSize (stx : Syntax) : Nat :=
match stx.getTailInfo? with
| some (SourceInfo.original (trailing := trailing) ..) => trailing.bsize
| _ => 0
/--
Return substring of original input covering `stx`.
Result is meaningful only if all involved `SourceInfo.original`s refer to the same string (as is the case after parsing). -/
def getSubstring? (stx : Syntax) (withLeading := true) (withTrailing := true) : Option Substring :=
match stx.getHeadInfo, stx.getTailInfo with
| SourceInfo.original lead startPos _ _, SourceInfo.original _ _ trail stopPos =>
some {
str := lead.str
startPos := if withLeading then lead.startPos else startPos
stopPos := if withTrailing then trail.stopPos else stopPos
}
| _, _ => none
@[specialize] private partial def updateLast {α} [Inhabited α] (a : Array α) (f : α → Option α) (i : Nat) : Option (Array α) :=
if i == 0 then
none
else
let i := i - 1
let v := a[i]
match f v with
| some v => some <| a.set! i v
| none => updateLast a f i
partial def setTailInfoAux (info : SourceInfo) : Syntax → Option Syntax
| atom _ val => some <| atom info val
| ident _ rawVal val pre => some <| ident info rawVal val pre
| node info k args =>
match updateLast args (setTailInfoAux info) args.size with
| some args => some <| node info k args
| none => none
| stx => none
def setTailInfo (stx : Syntax) (info : SourceInfo) : Syntax :=
match setTailInfoAux info stx with
| some stx => stx
| none => stx
def unsetTrailing (stx : Syntax) : Syntax :=
match stx.getTailInfo with
| SourceInfo.original lead pos trail endPos => stx.setTailInfo (SourceInfo.original lead pos "".toSubstring endPos)
| _ => stx
@[specialize] private partial def updateFirst {α} [Inhabited α] (a : Array α) (f : α → Option α) (i : Nat) : Option (Array α) :=
if h : i < a.size then
let v := a.get ⟨i, h⟩;
match f v with
| some v => some <| a.set ⟨i, h⟩ v
| none => updateFirst a f (i+1)
else
none
partial def setHeadInfoAux (info : SourceInfo) : Syntax → Option Syntax
| atom _ val => some <| atom info val
| ident _ rawVal val pre => some <| ident info rawVal val pre
| node i k args =>
match updateFirst args (setHeadInfoAux info) 0 with
| some args => some <| node i k args
| noxne => none
| stx => none
def setHeadInfo (stx : Syntax) (info : SourceInfo) : Syntax :=
match setHeadInfoAux info stx with
| some stx => stx
| none => stx
def setInfo (info : SourceInfo) : Syntax → Syntax
| atom _ val => atom info val
| ident _ rawVal val pre => ident info rawVal val pre
| node _ kind args => node info kind args
| missing => missing
/-- Return the first atom/identifier that has position information -/
partial def getHead? : Syntax → Option Syntax
| stx@(atom info ..) => info.getPos?.map fun _ => stx
| stx@(ident info ..) => info.getPos?.map fun _ => stx
| node SourceInfo.none _ args => args.findSome? getHead?
| stx@(node info _ _) => stx
| _ => none
def copyHeadTailInfoFrom (target source : Syntax) : Syntax :=
target.setHeadInfo source.getHeadInfo |>.setTailInfo source.getTailInfo
end Syntax
/-- Use the head atom/identifier of the current `ref` as the `ref` -/
@[inline] def withHeadRefOnly {m : Type → Type} [Monad m] [MonadRef m] {α} (x : m α) : m α := do
match (← getRef).getHead? with
| none => x
| some ref => withRef ref x
@[inline] def mkNode (k : SyntaxNodeKind) (args : Array Syntax) : Syntax :=
Syntax.node SourceInfo.none k args
/- Syntax objects for a Lean module. -/
structure Module where
header : Syntax
commands : Array Syntax
/-- Expand all macros in the given syntax -/
partial def expandMacros : Syntax → MacroM Syntax
| stx@(Syntax.node info k args) => do
match (← expandMacro? stx) with
| some stxNew => expandMacros stxNew
| none => do
let args ← Macro.withIncRecDepth stx <| args.mapM expandMacros
pure <| Syntax.node info k args
| stx => pure stx
/- Helper functions for processing Syntax programmatically -/
/--
Create an identifier copying the position from `src`.
To refer to a specific constant, use `mkCIdentFrom` instead. -/
def mkIdentFrom (src : Syntax) (val : Name) : Syntax :=
Syntax.ident (SourceInfo.fromRef src) (toString val).toSubstring val []
def mkIdentFromRef [Monad m] [MonadRef m] (val : Name) : m Syntax := do
return mkIdentFrom (← getRef) val
/--
Create an identifier referring to a constant `c` copying the position from `src`.
This variant of `mkIdentFrom` makes sure that the identifier cannot accidentally
be captured. -/
def mkCIdentFrom (src : Syntax) (c : Name) : Syntax :=
-- Remark: We use the reserved macro scope to make sure there are no accidental collision with our frontend
let id := addMacroScope `_internal c reservedMacroScope
Syntax.ident (SourceInfo.fromRef src) (toString id).toSubstring id [(c, [])]
def mkCIdentFromRef [Monad m] [MonadRef m] (c : Name) : m Syntax := do
return mkCIdentFrom (← getRef) c
def mkCIdent (c : Name) : Syntax :=
mkCIdentFrom Syntax.missing c
@[export lean_mk_syntax_ident]
def mkIdent (val : Name) : Syntax :=
Syntax.ident SourceInfo.none (toString val).toSubstring val []
@[inline] def mkNullNode (args : Array Syntax := #[]) : Syntax :=
mkNode nullKind args
@[inline] def mkGroupNode (args : Array Syntax := #[]) : Syntax :=
mkNode groupKind args
def mkSepArray (as : Array Syntax) (sep : Syntax) : Array Syntax := Id.run <| do
let mut i := 0
let mut r := #[]
for a in as do
if i > 0 then
r := r.push sep |>.push a
else
r := r.push a
i := i + 1
return r
def mkOptionalNode (arg : Option Syntax) : Syntax :=
match arg with
| some arg => mkNullNode #[arg]
| none => mkNullNode #[]
def mkHole (ref : Syntax) : Syntax :=
mkNode `Lean.Parser.Term.hole #[mkAtomFrom ref "_"]
namespace Syntax
def mkSep (a : Array Syntax) (sep : Syntax) : Syntax :=
mkNullNode <| mkSepArray a sep
def SepArray.ofElems {sep} (elems : Array Syntax) : SepArray sep :=
⟨mkSepArray elems (mkAtom sep)⟩
def SepArray.ofElemsUsingRef [Monad m] [MonadRef m] {sep} (elems : Array Syntax) : m (SepArray sep) := do
let ref ← getRef;
return ⟨mkSepArray elems (mkAtomFrom ref sep)⟩
instance (sep) : Coe (Array Syntax) (SepArray sep) where
coe := SepArray.ofElems
/-- Create syntax representing a Lean term application, but avoid degenerate empty applications. -/
def mkApp (fn : Syntax) : (args : Array Syntax) → Syntax
| #[] => fn
| args => mkNode `Lean.Parser.Term.app #[fn, mkNullNode args]
def mkCApp (fn : Name) (args : Array Syntax) : Syntax :=
mkApp (mkCIdent fn) args
def mkLit (kind : SyntaxNodeKind) (val : String) (info := SourceInfo.none) : Syntax :=
let atom : Syntax := Syntax.atom info val
mkNode kind #[atom]
def mkStrLit (val : String) (info := SourceInfo.none) : Syntax :=
mkLit strLitKind (String.quote val) info
def mkNumLit (val : String) (info := SourceInfo.none) : Syntax :=
mkLit numLitKind val info
def mkScientificLit (val : String) (info := SourceInfo.none) : Syntax :=
mkLit scientificLitKind val info
def mkNameLit (val : String) (info := SourceInfo.none) : Syntax :=
mkLit nameLitKind val info
/- Recall that we don't have special Syntax constructors for storing numeric and string atoms.
The idea is to have an extensible approach where embedded DSLs may have new kind of atoms and/or
different ways of representing them. So, our atoms contain just the parsed string.
The main Lean parser uses the kind `numLitKind` for storing natural numbers that can be encoded
in binary, octal, decimal and hexadecimal format. `isNatLit` implements a "decoder"
for Syntax objects representing these numerals. -/
private partial def decodeBinLitAux (s : String) (i : String.Pos) (val : Nat) : Option Nat :=
if s.atEnd i then some val
else
let c := s.get i
if c == '0' then decodeBinLitAux s (s.next i) (2*val)
else if c == '1' then decodeBinLitAux s (s.next i) (2*val + 1)
else none
private partial def decodeOctalLitAux (s : String) (i : String.Pos) (val : Nat) : Option Nat :=
if s.atEnd i then some val
else
let c := s.get i
if '0' ≤ c && c ≤ '7' then decodeOctalLitAux s (s.next i) (8*val + c.toNat - '0'.toNat)
else none
private def decodeHexDigit (s : String) (i : String.Pos) : Option (Nat × String.Pos) :=
let c := s.get i
let i := s.next i
if '0' ≤ c && c ≤ '9' then some (c.toNat - '0'.toNat, i)
else if 'a' ≤ c && c ≤ 'f' then some (10 + c.toNat - 'a'.toNat, i)
else if 'A' ≤ c && c ≤ 'F' then some (10 + c.toNat - 'A'.toNat, i)
else none
private partial def decodeHexLitAux (s : String) (i : String.Pos) (val : Nat) : Option Nat :=
if s.atEnd i then some val
else match decodeHexDigit s i with
| some (d, i) => decodeHexLitAux s i (16*val + d)
| none => none
private partial def decodeDecimalLitAux (s : String) (i : String.Pos) (val : Nat) : Option Nat :=
if s.atEnd i then some val
else
let c := s.get i
if '0' ≤ c && c ≤ '9' then decodeDecimalLitAux s (s.next i) (10*val + c.toNat - '0'.toNat)
else none
def decodeNatLitVal? (s : String) : Option Nat :=
let len := s.length
if len == 0 then none
else
let c := s.get 0
if c == '0' then
if len == 1 then some 0
else
let c := s.get 1
if c == 'x' || c == 'X' then decodeHexLitAux s 2 0
else if c == 'b' || c == 'B' then decodeBinLitAux s 2 0
else if c == 'o' || c == 'O' then decodeOctalLitAux s 2 0
else if c.isDigit then decodeDecimalLitAux s 0 0
else none
else if c.isDigit then decodeDecimalLitAux s 0 0
else none
def isLit? (litKind : SyntaxNodeKind) (stx : Syntax) : Option String :=
match stx with
| Syntax.node _ k args =>
if k == litKind && args.size == 1 then
match args.get! 0 with
| (Syntax.atom _ val) => some val
| _ => none
else
none
| _ => none
private def isNatLitAux (litKind : SyntaxNodeKind) (stx : Syntax) : Option Nat :=
match isLit? litKind stx with
| some val => decodeNatLitVal? val
| _ => none
def isNatLit? (s : Syntax) : Option Nat :=
isNatLitAux numLitKind s
def isFieldIdx? (s : Syntax) : Option Nat :=
isNatLitAux fieldIdxKind s
partial def decodeScientificLitVal? (s : String) : Option (Nat × Bool × Nat) :=
let len := s.length
if len == 0 then none
else
let c := s.get 0
if c.isDigit then
decode 0 0
else none
where
decodeAfterExp (i : String.Pos) (val : Nat) (e : Nat) (sign : Bool) (exp : Nat) : Option (Nat × Bool × Nat) :=
if s.atEnd i then
if sign then
some (val, sign, exp + e)
else if exp >= e then
some (val, sign, exp - e)
else
some (val, true, e - exp)
else
let c := s.get i
if '0' ≤ c && c ≤ '9' then
decodeAfterExp (s.next i) val e sign (10*exp + c.toNat - '0'.toNat)
else
none
decodeExp (i : String.Pos) (val : Nat) (e : Nat) : Option (Nat × Bool × Nat) :=
let c := s.get i
if c == '-' then
decodeAfterExp (s.next i) val e true 0
else
decodeAfterExp i val e false 0
decodeAfterDot (i : String.Pos) (val : Nat) (e : Nat) : Option (Nat × Bool × Nat) :=
if s.atEnd i then
some (val, true, e)
else
let c := s.get i
if '0' ≤ c && c ≤ '9' then
decodeAfterDot (s.next i) (10*val + c.toNat - '0'.toNat) (e+1)
else if c == 'e' || c == 'E' then
decodeExp (s.next i) val e
else
none
decode (i : String.Pos) (val : Nat) : Option (Nat × Bool × Nat) :=
if s.atEnd i then
none
else
let c := s.get i
if '0' ≤ c && c ≤ '9' then
decode (s.next i) (10*val + c.toNat - '0'.toNat)
else if c == '.' then
decodeAfterDot (s.next i) val 0
else if c == 'e' || c == 'E' then
decodeExp (s.next i) val 0
else
none
def isScientificLit? (stx : Syntax) : Option (Nat × Bool × Nat) :=
match isLit? scientificLitKind stx with
| some val => decodeScientificLitVal? val
| _ => none
def isIdOrAtom? : Syntax → Option String
| Syntax.atom _ val => some val
| Syntax.ident _ rawVal _ _ => some rawVal.toString
| _ => none
def toNat (stx : Syntax) : Nat :=
match stx.isNatLit? with
| some val => val
| none => 0
def decodeQuotedChar (s : String) (i : String.Pos) : Option (Char × String.Pos) :=
OptionM.run do
let c := s.get i
let i := s.next i
if c == '\\' then pure ('\\', i)
else if c = '\"' then pure ('\"', i)
else if c = '\'' then pure ('\'', i)
else if c = 'r' then pure ('\r', i)
else if c = 'n' then pure ('\n', i)
else if c = 't' then pure ('\t', i)
else if c = 'x' then
let (d₁, i) ← decodeHexDigit s i
let (d₂, i) ← decodeHexDigit s i
pure (Char.ofNat (16*d₁ + d₂), i)
else if c = 'u' then do
let (d₁, i) ← decodeHexDigit s i
let (d₂, i) ← decodeHexDigit s i
let (d₃, i) ← decodeHexDigit s i
let (d₄, i) ← decodeHexDigit s i
pure (Char.ofNat (16*(16*(16*d₁ + d₂) + d₃) + d₄), i)
else
none
partial def decodeStrLitAux (s : String) (i : String.Pos) (acc : String) : Option String :=
OptionM.run do
let c := s.get i
let i := s.next i
if c == '\"' then
pure acc
else if s.atEnd i then
none
else if c == '\\' then do
let (c, i) ← decodeQuotedChar s i
decodeStrLitAux s i (acc.push c)
else
decodeStrLitAux s i (acc.push c)
def decodeStrLit (s : String) : Option String :=
decodeStrLitAux s 1 ""
def isStrLit? (stx : Syntax) : Option String :=
match isLit? strLitKind stx with
| some val => decodeStrLit val
| _ => none
def decodeCharLit (s : String) : Option Char :=
OptionM.run do
let c := s.get 1
if c == '\\' then do
let (c, _) ← decodeQuotedChar s 2
pure c
else
pure c
def isCharLit? (stx : Syntax) : Option Char :=
match isLit? charLitKind stx with
| some val => decodeCharLit val
| _ => none
private partial def splitNameLitAux (ss : Substring) (acc : List Substring) : List Substring :=
let splitRest (ss : Substring) (acc : List Substring) : List Substring :=
if ss.front == '.' then
splitNameLitAux (ss.drop 1) acc
else if ss.isEmpty then
acc
else
[]
if ss.isEmpty then []
else
let curr := ss.front
if isIdBeginEscape curr then
let escapedPart := ss.takeWhile (!isIdEndEscape ·)
let escapedPart := { escapedPart with stopPos := ss.stopPos.min (escapedPart.str.next escapedPart.stopPos) }
if !isIdEndEscape (escapedPart.get <| escapedPart.prev escapedPart.bsize) then []
else splitRest (ss.extract escapedPart.bsize ss.bsize) (escapedPart :: acc)
else if isIdFirst curr then
let idPart := ss.takeWhile isIdRest
splitRest (ss.extract idPart.bsize ss.bsize) (idPart :: acc)
else if curr.isDigit then
let idPart := ss.takeWhile Char.isDigit
splitRest (ss.extract idPart.bsize ss.bsize) (idPart :: acc)
else
[]
/-- Split a name literal (without the backtick) into its dot-separated components. For example,
`foo.bla.«bo.o»` ↦ `["foo", "bla", "«bo.o»"]`. If the literal cannot be parsed, return `[]`. -/
def splitNameLit (ss : Substring) : List Substring :=
splitNameLitAux ss [] |>.reverse
def decodeNameLit (s : String) : Option Name :=
if s.get 0 == '`' then
match splitNameLitAux (s.toSubstring.drop 1) [] with
| [] => none
| comps => some <| comps.foldr (init := Name.anonymous)
fun comp n =>
let comp := comp.toString
if isIdBeginEscape comp.front then
Name.mkStr n (comp.drop 1 |>.dropRight 1)
else if comp.front.isDigit then
if let some k := decodeNatLitVal? comp then
Name.mkNum n k
else
unreachable!
else
Name.mkStr n comp
else
none
def isNameLit? (stx : Syntax) : Option Name :=
match isLit? nameLitKind stx with
| some val => decodeNameLit val
| _ => none
def hasArgs : Syntax → Bool
| Syntax.node _ _ args => args.size > 0
| _ => false
def isAtom : Syntax → Bool
| atom _ _ => true
| _ => false
def isToken (token : String) : Syntax → Bool
| atom _ val => val.trim == token.trim
| _ => false
def isNone (stx : Syntax) : Bool :=
match stx with
| Syntax.node _ k args => k == nullKind && args.size == 0
-- when elaborating partial syntax trees, it's reasonable to interpret missing parts as `none`
| Syntax.missing => true
| _ => false
def getOptional? (stx : Syntax) : Option Syntax :=
match stx with
| Syntax.node _ k args => if k == nullKind && args.size == 1 then some (args.get! 0) else none
| _ => none
def getOptionalIdent? (stx : Syntax) : Option Name :=
match stx.getOptional? with
| some stx => some stx.getId
| none => none
partial def findAux (p : Syntax → Bool) : Syntax → Option Syntax
| stx@(Syntax.node _ _ args) => if p stx then some stx else args.findSome? (findAux p)
| stx => if p stx then some stx else none
def find? (stx : Syntax) (p : Syntax → Bool) : Option Syntax :=
findAux p stx
end Syntax
/-- Reflect a runtime datum back to surface syntax (best-effort). -/
class Quote (α : Type) where
quote : α → Syntax
export Quote (quote)
instance : Quote Syntax := ⟨id⟩
instance : Quote Bool := ⟨fun | true => mkCIdent `Bool.true | false => mkCIdent `Bool.false⟩
instance : Quote String := ⟨Syntax.mkStrLit⟩
instance : Quote Nat := ⟨fun n => Syntax.mkNumLit <| toString n⟩
instance : Quote Substring := ⟨fun s => Syntax.mkCApp `String.toSubstring #[quote s.toString]⟩
-- in contrast to `Name.toString`, we can, and want to be, precise here
private def getEscapedNameParts? (acc : List String) : Name → OptionM (List String)
| Name.anonymous => acc
| Name.str n s _ => do
let s ← Name.escapePart s
getEscapedNameParts? (s::acc) n
| Name.num n i _ => none
private def quoteNameMk : Name → Syntax
| Name.anonymous => mkCIdent ``Name.anonymous
| Name.str n s _ => Syntax.mkCApp ``Name.mkStr #[quoteNameMk n, quote s]
| Name.num n i _ => Syntax.mkCApp ``Name.mkNum #[quoteNameMk n, quote i]
instance : Quote Name where
quote n := match getEscapedNameParts? [] n with
| some ss => mkNode `Lean.Parser.Term.quotedName #[Syntax.mkNameLit ("`" ++ ".".intercalate ss)]
| none => quoteNameMk n
instance {α β : Type} [Quote α] [Quote β] : Quote (α × β) where
quote
| ⟨a, b⟩ => Syntax.mkCApp ``Prod.mk #[quote a, quote b]
private def quoteList {α : Type} [Quote α] : List α → Syntax
| [] => mkCIdent ``List.nil
| (x::xs) => Syntax.mkCApp ``List.cons #[quote x, quoteList xs]
instance {α : Type} [Quote α] : Quote (List α) where
quote := quoteList
instance {α : Type} [Quote α] : Quote (Array α) where
quote xs := Syntax.mkCApp ``List.toArray #[quote xs.toList]
private def quoteOption {α : Type} [Quote α] : Option α → Syntax
| none => mkIdent ``none
| (some x) => Syntax.mkCApp ``some #[quote x]
instance Option.hasQuote {α : Type} [Quote α] : Quote (Option α) where
quote := quoteOption
/- Evaluator for `prec` DSL -/
def evalPrec (stx : Syntax) : MacroM Nat :=
Macro.withIncRecDepth stx do
let stx ← expandMacros stx
match stx with
| `(prec| $num:numLit) => return num.isNatLit?.getD 0
| _ => Macro.throwErrorAt stx "unexpected precedence"
macro_rules
| `(prec| $a + $b) => do `(prec| $(quote <| (← evalPrec a) + (← evalPrec b)):numLit)
macro_rules
| `(prec| $a - $b) => do `(prec| $(quote <| (← evalPrec a) - (← evalPrec b)):numLit)
macro "eval_prec " p:prec:max : term => return quote (← evalPrec p)
/- Evaluator for `prio` DSL -/
def evalPrio (stx : Syntax) : MacroM Nat :=
Macro.withIncRecDepth stx do
let stx ← expandMacros stx
match stx with
| `(prio| $num:numLit) => return num.isNatLit?.getD 0
| _ => Macro.throwErrorAt stx "unexpected priority"
macro_rules
| `(prio| $a + $b) => do `(prio| $(quote <| (← evalPrio a) + (← evalPrio b)):numLit)
macro_rules
| `(prio| $a - $b) => do `(prio| $(quote <| (← evalPrio a) - (← evalPrio b)):numLit)
macro "eval_prio " p:prio:max : term => return quote (← evalPrio p)
def evalOptPrio : Option Syntax → MacroM Nat
| some prio => evalPrio prio
| none => return eval_prio default
end Lean
namespace Array
abbrev getSepElems := @getEvenElems
open Lean
private partial def filterSepElemsMAux {m : Type → Type} [Monad m] (a : Array Syntax) (p : Syntax → m Bool) (i : Nat) (acc : Array Syntax) : m (Array Syntax) := do
if h : i < a.size then
let stx := a.get ⟨i, h⟩
if (← p stx) then
if acc.isEmpty then
filterSepElemsMAux a p (i+2) (acc.push stx)
else if hz : i ≠ 0 then
have : i.pred < i := Nat.pred_lt hz
let sepStx := a.get ⟨i.pred, Nat.lt_trans this h⟩
filterSepElemsMAux a p (i+2) ((acc.push sepStx).push stx)
else
filterSepElemsMAux a p (i+2) (acc.push stx)
else
filterSepElemsMAux a p (i+2) acc
else
pure acc
def filterSepElemsM {m : Type → Type} [Monad m] (a : Array Syntax) (p : Syntax → m Bool) : m (Array Syntax) :=
filterSepElemsMAux a p 0 #[]
def filterSepElems (a : Array Syntax) (p : Syntax → Bool) : Array Syntax :=
Id.run <| a.filterSepElemsM p
private partial def mapSepElemsMAux {m : Type → Type} [Monad m] (a : Array Syntax) (f : Syntax → m Syntax) (i : Nat) (acc : Array Syntax) : m (Array Syntax) := do
if h : i < a.size then
let stx := a.get ⟨i, h⟩
if i % 2 == 0 then do
let stx ← f stx
mapSepElemsMAux a f (i+1) (acc.push stx)
else
mapSepElemsMAux a f (i+1) (acc.push stx)
else
pure acc
def mapSepElemsM {m : Type → Type} [Monad m] (a : Array Syntax) (f : Syntax → m Syntax) : m (Array Syntax) :=
mapSepElemsMAux a f 0 #[]
def mapSepElems (a : Array Syntax) (f : Syntax → Syntax) : Array Syntax :=
Id.run <| a.mapSepElemsM f
end Array
namespace Lean.Syntax.SepArray
def getElems {sep} (sa : SepArray sep) : Array Syntax :=
sa.elemsAndSeps.getSepElems
/-
We use `CoeTail` here instead of `Coe` to avoid a "loop" when computing `CoeTC`.
The "loop" is interrupted using the maximum instance size threshold, but it is a performance bottleneck.
The loop occurs because the predicate `isNewAnswer` is too imprecise.
-/
instance (sep) : CoeTail (SepArray sep) (Array Syntax) where
coe := getElems
end Lean.Syntax.SepArray
/--
Gadget for automatic parameter support. This is similar to the `optParam` gadget, but it uses
the given tactic.
Like `optParam`, this gadget only affects elaboration.
For example, the tactic will *not* be invoked during type class resolution. -/
abbrev autoParam.{u} (α : Sort u) (tactic : Lean.Syntax) : Sort u := α
/- Helper functions for manipulating interpolated strings -/
namespace Lean.Syntax
private def decodeInterpStrQuotedChar (s : String) (i : String.Pos) : Option (Char × String.Pos) :=
OptionM.run do
match decodeQuotedChar s i with
| some r => some r
| none =>
let c := s.get i
let i := s.next i
if c == '{' then pure ('{', i)
else none
private partial def decodeInterpStrLit (s : String) : Option String :=
let rec loop (i : String.Pos) (acc : String) : OptionM String :=
let c := s.get i
let i := s.next i
if c == '\"' || c == '{' then
pure acc
else if s.atEnd i then
none
else if c == '\\' then do
let (c, i) ← decodeInterpStrQuotedChar s i
loop i (acc.push c)
else
loop i (acc.push c)
loop 1 ""
partial def isInterpolatedStrLit? (stx : Syntax) : Option String :=
match isLit? interpolatedStrLitKind stx with
| none => none
| some val => decodeInterpStrLit val
def expandInterpolatedStrChunks (chunks : Array Syntax) (mkAppend : Syntax → Syntax → MacroM Syntax) (mkElem : Syntax → MacroM Syntax) : MacroM Syntax := do
let mut i := 0
let mut result := Syntax.missing
for elem in chunks do
let elem ← match elem.isInterpolatedStrLit? with
| none => mkElem elem
| some str => mkElem (Syntax.mkStrLit str)
if i == 0 then
result := elem
else
result ← mkAppend result elem
i := i+1
return result
def expandInterpolatedStr (interpStr : Syntax) (type : Syntax) (toTypeFn : Syntax) : MacroM Syntax := do
let ref := interpStr
let r ← expandInterpolatedStrChunks interpStr.getArgs (fun a b => `($a ++ $b)) (fun a => `($toTypeFn $a))
`(($r : $type))
def getSepArgs (stx : Syntax) : Array Syntax :=
stx.getArgs.getSepElems
end Syntax
namespace Meta
inductive TransparencyMode where
| all | default | reducible | instances
deriving Inhabited, BEq, Repr
namespace Simp
def defaultMaxSteps := 100000
structure Config where
maxSteps : Nat := defaultMaxSteps
maxDischargeDepth : Nat := 2
contextual : Bool := false
memoize : Bool := true
singlePass : Bool := false
zeta : Bool := true
beta : Bool := true
eta : Bool := true
etaStruct : Bool := true
iota : Bool := true
proj : Bool := true
decide : Bool := true
deriving Inhabited, BEq, Repr
-- Configuration object for `simp_all`
structure ConfigCtx extends Config where
contextual := true
end Simp
namespace Rewrite
structure Config where
transparency : TransparencyMode := TransparencyMode.reducible
offsetCnstrs : Bool := true
end Rewrite
end Meta
namespace Parser.Tactic
macro "erw " s:rwRuleSeq loc:(location)? : tactic =>
`(rw (config := { transparency := Lean.Meta.TransparencyMode.default }) $s:rwRuleSeq $[$(loc.getOptional?):location]?)
end Parser.Tactic
end Lean
|
a12a2804eb43a6da263ce3a5713f28c49021e80b | f5f7e6fae601a5fe3cac7cc3ed353ed781d62419 | /src/algebra/char_p.lean | f5c20337acf2478a4de90a43da1d48bf03af63c0 | [
"Apache-2.0"
] | permissive | EdAyers/mathlib | 9ecfb2f14bd6caad748b64c9c131befbff0fb4e0 | ca5d4c1f16f9c451cf7170b10105d0051db79e1b | refs/heads/master | 1,626,189,395,845 | 1,555,284,396,000 | 1,555,284,396,000 | 144,004,030 | 0 | 0 | Apache-2.0 | 1,533,727,664,000 | 1,533,727,663,000 | null | UTF-8 | Lean | false | false | 8,716 | lean | /-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Kenny Lau, Joey van Langen, Casper Putz
Characteristic of semirings.
-/
import data.padics.padic_norm data.nat.choose data.fintype data.set
import data.zmod.basic algebra.module
universes u v
/-- The generator of the kernel of the unique homomorphism ℤ → α for a semiring α -/
class char_p (α : Type u) [semiring α] (p : ℕ) : Prop :=
(cast_eq_zero_iff : ∀ x:ℕ, (x:α) = 0 ↔ p ∣ x)
theorem char_p.cast_eq_zero (α : Type u) [semiring α] (p : ℕ) [char_p α p] : (p:α) = 0 :=
(char_p.cast_eq_zero_iff α p p).2 (dvd_refl p)
theorem char_p.eq (α : Type u) [semiring α] {p q : ℕ} (c1 : char_p α p) (c2 : char_p α q) : p = q :=
nat.dvd_antisymm
((char_p.cast_eq_zero_iff α p q).1 (char_p.cast_eq_zero _ _))
((char_p.cast_eq_zero_iff α q p).1 (char_p.cast_eq_zero _ _))
instance char_p.of_char_zero (α : Type u) [semiring α] [char_zero α] : char_p α 0 :=
⟨λ x, by rw [zero_dvd_iff, ← nat.cast_zero, nat.cast_inj]⟩
theorem char_p.exists (α : Type u) [semiring α] : ∃ p, char_p α p :=
by letI := classical.dec_eq α; exact
classical.by_cases
(assume H : ∀ p:ℕ, (p:α) = 0 → p = 0, ⟨0,
⟨λ x, by rw [zero_dvd_iff]; exact ⟨H x, by rintro rfl; refl⟩⟩⟩)
(λ H, ⟨nat.find (classical.not_forall.1 H), ⟨λ x,
⟨λ H1, nat.dvd_of_mod_eq_zero (by_contradiction $ λ H2,
nat.find_min (classical.not_forall.1 H)
(nat.mod_lt x $ nat.pos_of_ne_zero $ not_of_not_imp $
nat.find_spec (classical.not_forall.1 H))
(not_imp_of_and_not ⟨by rwa [← nat.mod_add_div x (nat.find (classical.not_forall.1 H)),
nat.cast_add, nat.cast_mul, of_not_not (not_not_of_not_imp $ nat.find_spec (classical.not_forall.1 H)),
zero_mul, add_zero] at H1, H2⟩)),
λ H1, by rw [← nat.mul_div_cancel' H1, nat.cast_mul,
of_not_not (not_not_of_not_imp $ nat.find_spec (classical.not_forall.1 H)), zero_mul]⟩⟩⟩)
theorem char_p.exists_unique (α : Type u) [semiring α] : ∃! p, char_p α p :=
let ⟨c, H⟩ := char_p.exists α in ⟨c, H, λ y H2, char_p.eq α H2 H⟩
/-- Noncomuptable function that outputs the unique characteristic of a semiring. -/
noncomputable def ring_char (α : Type u) [semiring α] : ℕ :=
classical.some (char_p.exists_unique α)
theorem ring_char.spec (α : Type u) [semiring α] : ∀ x:ℕ, (x:α) = 0 ↔ ring_char α ∣ x :=
by letI := (classical.some_spec (char_p.exists_unique α)).1;
unfold ring_char; exact char_p.cast_eq_zero_iff α (ring_char α)
theorem ring_char.eq (α : Type u) [semiring α] {p : ℕ} (C : char_p α p) : p = ring_char α :=
(classical.some_spec (char_p.exists_unique α)).2 p C
theorem add_pow_char (α : Type u) [comm_ring α] {p : ℕ} (hp : nat.prime p)
[char_p α p] (x y : α) : (x + y)^p = x^p + y^p :=
begin
rw [add_pow, finset.sum_range_succ, nat.sub_self, pow_zero, choose_self],
rw [nat.cast_one, mul_one, mul_one, add_left_inj],
transitivity,
{ refine finset.sum_eq_single 0 _ _,
{ intros b h1 h2,
have := nat.prime.dvd_choose (nat.pos_of_ne_zero h2) (finset.mem_range.1 h1) hp,
rw [← nat.div_mul_cancel this, nat.cast_mul, char_p.cast_eq_zero α p],
simp only [mul_zero] },
{ intro H, exfalso, apply H, exact finset.mem_range.2 hp.pos } },
rw [pow_zero, nat.sub_zero, one_mul, choose_zero_right, nat.cast_one, mul_one]
end
/-- The frobenius map that sends x to x^p -/
def frobenius (α : Type u) [monoid α] (p : ℕ) (x : α) : α := x^p
theorem frobenius_def (α : Type u) [monoid α] (p : ℕ) (x : α) : frobenius α p x = x ^ p := rfl
theorem frobenius_mul (α : Type u) [comm_monoid α] (p : ℕ) (x y : α) :
frobenius α p (x * y) = frobenius α p x * frobenius α p y := mul_pow x y p
theorem frobenius_one (α : Type u) [monoid α] (p : ℕ) :
frobenius α p 1 = 1 := one_pow _
theorem is_monoid_hom.map_frobenius {α : Type u} {β : Type v} [monoid α] [monoid β] (f : α → β) [is_monoid_hom f]
(p : ℕ) (x : α) : f (frobenius α p x) = frobenius β p (f x) :=
by unfold frobenius; induction p; simp only [pow_zero, pow_succ,
is_monoid_hom.map_one f, is_monoid_hom.map_mul f, *]
instance {α : Type u} [comm_ring α] (p : ℕ) [hp : nat.prime p] [char_p α p] : is_ring_hom (frobenius α p) :=
{ map_one := frobenius_one α p,
map_mul := frobenius_mul α p,
map_add := add_pow_char α hp }
section
variables (α : Type u) [comm_ring α] (p : ℕ) [hp : nat.prime p]
theorem frobenius_zero : frobenius α p 0 = 0 := zero_pow hp.pos
variables [char_p α p] (x y : α)
include hp
theorem frobenius_add : frobenius α p (x + y) = frobenius α p x + frobenius α p y := is_ring_hom.map_add _
theorem frobenius_neg : frobenius α p (-x) = -frobenius α p x := is_ring_hom.map_neg _
theorem frobenius_sub : frobenius α p (x - y) = frobenius α p x - frobenius α p y := is_ring_hom.map_sub _
end
theorem frobenius_inj (α : Type u) [integral_domain α] (p : ℕ) [nat.prime p] [char_p α p] (x y : α)
(H : frobenius α p x = frobenius α p y) : x = y :=
by rw ← sub_eq_zero at H ⊢; rw ← frobenius_sub at H; exact pow_eq_zero H
theorem frobenius_nat_cast (α : Type u) [comm_ring α] (p : ℕ) [nat.prime p] [char_p α p] (x : ℕ) :
frobenius α p x = x :=
by induction x; simp only [nat.cast_zero, nat.cast_succ, frobenius_zero, frobenius_one, frobenius_add, *]
namespace char_p
section
variables (α : Type u) [ring α]
lemma char_p_to_char_zero [char_p α 0] : char_zero α :=
add_group.char_zero_of_inj_zero $
λ n h0, eq_zero_of_zero_dvd ((cast_eq_zero_iff α 0 n).mp h0)
lemma cast_eq_mod (p : ℕ) [char_p α p] (k : ℕ) : (k : α) = (k % p : ℕ) :=
calc (k : α) = ↑(k % p + p * (k / p)) : by rw [nat.mod_add_div]
... = ↑(k % p) : by simp[cast_eq_zero]
theorem char_ne_zero_of_fintype (p : ℕ) [hc : char_p α p] [fintype α] [decidable_eq α] : p ≠ 0 :=
assume h : p = 0,
have char_zero α := @char_p_to_char_zero α _ (h ▸ hc),
absurd (@nat.cast_injective α _ _ this) (@set.not_injective_nat_fintype α _ _ _)
end
section integral_domain
open nat
variables (α : Type u) [integral_domain α]
theorem char_ne_one (p : ℕ) [hc : char_p α p] : p ≠ 1 :=
assume hp : p = 1,
have ( 1 : α) = 0, by simpa using (cast_eq_zero_iff α p 1).mpr (hp ▸ dvd_refl p),
absurd this one_ne_zero
theorem char_is_prime_of_ge_two (p : ℕ) [hc : char_p α p] (hp : p ≥ 2) : nat.prime p :=
suffices ∀d ∣ p, d = 1 ∨ d = p, from ⟨hp, this⟩,
assume (d : ℕ) (hdvd : ∃ e, p = d * e),
let ⟨e, hmul⟩ := hdvd in
have (p : α) = 0, from (cast_eq_zero_iff α p p).mpr (dvd_refl p),
have (d : α) * e = 0, from (@cast_mul α _ d e) ▸ (hmul ▸ this),
or.elim (no_zero_divisors.eq_zero_or_eq_zero_of_mul_eq_zero (d : α) e this)
(assume hd : (d : α) = 0,
have p ∣ d, from (cast_eq_zero_iff α p d).mp hd,
show d = 1 ∨ d = p, from or.inr (dvd_antisymm ⟨e, hmul⟩ this))
(assume he : (e : α) = 0,
have p ∣ e, from (cast_eq_zero_iff α p e).mp he,
have e ∣ p, from dvd_of_mul_left_eq d (eq.symm hmul),
have e = p, from dvd_antisymm ‹e ∣ p› ‹p ∣ e›,
have h₀ : p > 0, from gt_of_ge_of_gt hp (nat.zero_lt_succ 1),
have d * p = 1 * p, by rw ‹e = p› at hmul; rw [one_mul]; exact eq.symm hmul,
show d = 1 ∨ d = p, from or.inl (eq_of_mul_eq_mul_right h₀ this))
theorem char_is_prime_or_zero (p : ℕ) [hc : char_p α p] : nat.prime p ∨ p = 0 :=
match p, hc with
| 0, _ := or.inr rfl
| 1, hc := absurd (eq.refl (1 : ℕ)) (@char_ne_one α _ (1 : ℕ) hc)
| (m+2), hc := or.inl (@char_is_prime_of_ge_two α _ (m+2) hc (nat.le_add_left 2 m))
end
theorem char_is_prime [fintype α] [decidable_eq α] (p : ℕ) [char_p α p] : nat.prime p :=
or.resolve_right (char_is_prime_or_zero α p) (char_ne_zero_of_fintype α p)
end integral_domain
end char_p
namespace zmod
variables {α : Type u} [ring α] {n : ℕ+}
instance cast_is_ring_hom [char_p α n] : is_ring_hom (cast : zmod n → α) :=
{ map_one := by rw ←@nat.cast_one α _ _; exact eq.symm (char_p.cast_eq_mod α n 1),
map_mul := assume x y : zmod n, show ↑((x * y).val) = ↑(x.val) * ↑(y.val),
by rw [zmod.mul_val, ←char_p.cast_eq_mod, nat.cast_mul],
map_add := assume x y : zmod n, show ↑((x + y).val) = ↑(x.val) + ↑(y.val),
by rw [zmod.add_val, ←char_p.cast_eq_mod, nat.cast_add] }
instance to_module [char_p α n] : module (zmod n) α := is_ring_hom.to_module cast
instance to_module' {m : ℕ} {hm : m > 0} [hc : char_p α m] : module (zmod ⟨m, hm⟩) α :=
@zmod.to_module α _ ⟨m, hm⟩ hc
end zmod
|
eb0553a3d9839479e3721d1bc44d064be8b0d456 | 2eab05920d6eeb06665e1a6df77b3157354316ad | /src/tactic/suggest.lean | 4ac72a6d1b73d2714be6297895c9266d4f741d6a | [
"Apache-2.0"
] | permissive | ayush1801/mathlib | 78949b9f789f488148142221606bf15c02b960d2 | ce164e28f262acbb3de6281b3b03660a9f744e3c | refs/heads/master | 1,692,886,907,941 | 1,635,270,866,000 | 1,635,270,866,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 21,933 | lean | /-
Copyright (c) 2019 Lucas Allen. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Lucas Allen, Scott Morrison
-/
import data.mllist
import tactic.solve_by_elim
/-!
# `suggest` and `library_search`
`suggest` and `library_search` are a pair of tactics for applying lemmas from the library to the
current goal.
* `suggest` prints a list of `exact ...` or `refine ...` statements, which may produce new goals
* `library_search` prints a single `exact ...` which closes the goal, or fails
-/
namespace tactic
open native
namespace suggest
open solve_by_elim
/-- Map a name (typically a head symbol) to a "canonical" definitional synonym.
Given a name `n`, we want a name `n'` such that a sufficiently applied
expression with head symbol `n` is always definitionally equal to an expression
with head symbol `n'`.
Thus, we can search through all lemmas with a result type of `n'`
to solve a goal with head symbol `n`.
For example, `>` is mapped to `<` because `a > b` is definitionally equal to `b < a`,
and `not` is mapped to `false` because `¬ a` is definitionally equal to `p → false`
The default is that the original argument is returned, so `<` is just mapped to `<`.
`normalize_synonym` is called for every lemma in the library, so it needs to be fast.
-/
-- TODO this is a hack; if you suspect more cases here would help, please report them
meta def normalize_synonym : name → name
| `gt := `has_lt.lt
| `ge := `has_le.le
| `monotone := `has_le.le
| `not := `false
| n := n
/--
Compute the head symbol of an expression, then normalise synonyms.
This is only used when analysing the goal, so it is okay to do more expensive analysis here.
-/
-- We may want to tweak this further?
meta def allowed_head_symbols : expr → list name
-- We first have a various "customisations":
-- Because in `ℕ` `a.succ ≤ b` is definitionally `a < b`,
-- we add some special cases to allow looking for `<` lemmas even when the goal has a `≤`.
-- Note we only do this in the `ℕ` case, for performance.
| `(@has_le.le ℕ _ (nat.succ _) _) := [`has_le.le, `has_lt.lt]
| `(@ge ℕ _ _ (nat.succ _)) := [`has_le.le, `has_lt.lt]
| `(@has_le.le ℕ _ 1 _) := [`has_le.le, `has_lt.lt]
| `(@ge ℕ _ _ 1) := [`has_le.le, `has_lt.lt]
-- And then the generic cases:
| (expr.pi _ _ _ t) := allowed_head_symbols t
| (expr.app f _) := allowed_head_symbols f
| (expr.const n _) := [normalize_synonym n]
| _ := [`_]
.
/--
A declaration can match the head symbol of the current goal in four possible ways:
* `ex` : an exact match
* `mp` : the declaration returns an `iff`, and the right hand side matches the goal
* `mpr` : the declaration returns an `iff`, and the left hand side matches the goal
* `both`: the declaration returns an `iff`, and the both sides match the goal
-/
@[derive decidable_eq, derive inhabited]
inductive head_symbol_match
| ex | mp | mpr | both
open head_symbol_match
/-- a textual representation of a `head_symbol_match`, for trace debugging. -/
def head_symbol_match.to_string : head_symbol_match → string
| ex := "exact"
| mp := "iff.mp"
| mpr := "iff.mpr"
| both := "iff.mp and iff.mpr"
/-- Determine if, and in which way, a given expression matches the specified head symbol. -/
meta def match_head_symbol (hs : name_set) : expr → option head_symbol_match
| (expr.pi _ _ _ t) := match_head_symbol t
| `(%%a ↔ %%b) := if hs.contains `iff then some ex else
match (match_head_symbol a, match_head_symbol b) with
| (some ex, some ex) :=
some both
| (some ex, _) := some mpr
| (_, some ex) := some mp
| _ := none
end
| (expr.app f _) := match_head_symbol f
| (expr.const n _) := if hs.contains (normalize_synonym n) then some ex else none
| _ := if hs.contains `_ then some ex else none
/-- A package of `declaration` metadata, including the way in which its type matches the head symbol
which we are searching for. -/
meta structure decl_data :=
(d : declaration)
(n : name)
(m : head_symbol_match)
(l : ℕ) -- cached length of name
/--
Generate a `decl_data` from the given declaration if
it matches the head symbol `hs` for the current goal.
-/
-- We used to check here for private declarations, or declarations with certain suffixes.
-- It turns out `apply` is so fast, it's better to just try them all.
meta def process_declaration (hs : name_set) (d : declaration) : option decl_data :=
let n := d.to_name in
if !d.is_trusted || n.is_internal then
none
else
(λ m, ⟨d, n, m, n.length⟩) <$> match_head_symbol hs d.type
/-- Retrieve all library definitions with a given head symbol. -/
meta def library_defs (hs : name_set) : tactic (list decl_data) :=
do trace_if_enabled `suggest format!"Looking for lemmas with head symbols {hs}.",
env ← get_env,
let defs := env.decl_filter_map (process_declaration hs),
-- Sort by length; people like short proofs
let defs := defs.qsort(λ d₁ d₂, d₁.l ≤ d₂.l),
trace_if_enabled `suggest format!"Found {defs.length} relevant lemmas:",
trace_if_enabled `suggest $ defs.map (λ ⟨d, n, m, l⟩, (n, m.to_string)),
return defs
/--
We unpack any element of a list of `decl_data` corresponding to an `↔` statement that could apply
in both directions into two separate elements.
This ensures that both directions can be independently returned by `suggest`,
and avoids a problem where the application of one direction prevents
the application of the other direction. (See `exp_le_exp` in the tests.)
-/
meta def unpack_iff_both : list decl_data → list decl_data
| [] := []
| (⟨d, n, both, l⟩ :: L) := ⟨d, n, mp, l⟩ :: ⟨d, n, mpr, l⟩ :: unpack_iff_both L
| (⟨d, n, m, l⟩ :: L) := ⟨d, n, m, l⟩ :: unpack_iff_both L
/-- An extension to the option structure for `solve_by_elim`,
to specify a list of local hypotheses which must appear in any solution.
These are useful for constraining the results from `library_search` and `suggest`. -/
meta structure suggest_opt extends opt :=
(compulsory_hyps : list expr := [])
/--
Convert a `suggest_opt` structure to a `opt` structure suitable for `solve_by_elim`,
by setting the `accept` parameter to require that all complete solutions
use everything in `compulsory_hyps`.
-/
meta def suggest_opt.mk_accept (o : suggest_opt) : opt :=
{ accept := λ gs, o.accept gs >>
(guard $ o.compulsory_hyps.all (λ h, gs.any (λ g, g.contains_expr_or_mvar h))),
..o }
/--
Apply the lemma `e`, then attempt to close all goals using
`solve_by_elim opt`, failing if `close_goals = tt`
and there are any goals remaining.
Returns the number of subgoals which were closed using `solve_by_elim`.
-/
-- Implementation note: as this is used by both `library_search` and `suggest`,
-- we first run `solve_by_elim` separately on the independent goals,
-- whether or not `close_goals` is set,
-- and then run `solve_by_elim { all_goals := tt }`,
-- requiring that it succeeds if `close_goals = tt`.
meta def apply_and_solve (close_goals : bool) (opt : suggest_opt := { }) (e : expr) : tactic ℕ :=
do
trace_if_enabled `suggest format!"Trying to apply lemma: {e}",
apply e opt.to_apply_cfg,
trace_if_enabled `suggest format!"Applied lemma: {e}",
ng ← num_goals,
-- Phase 1
-- Run `solve_by_elim` on each "safe" goal separately, not worrying about failures.
-- (We only attempt the "safe" goals in this way in Phase 1.
-- In Phase 2 we will do backtracking search across all goals,
-- allowing us to guess solutions that involve data or unify metavariables,
-- but only as long as we can finish all goals.)
-- If `compulsory_hyps` is non-empty, we skip this phase and defer to phase 2.
try (guard (opt.compulsory_hyps = []) >>
any_goals (independent_goal >> solve_by_elim opt.to_opt)),
-- Phase 2
(done >> return ng) <|> (do
-- If there were any goals that we did not attempt solving in the first phase
-- (because they weren't propositional, or contained a metavariable)
-- as a second phase we attempt to solve all remaining goals at once
-- (with backtracking across goals).
((guard (opt.compulsory_hyps ≠ []) <|> any_goals (success_if_fail independent_goal) >> skip) >>
solve_by_elim { backtrack_all_goals := tt, ..opt.mk_accept }) <|>
-- and fail unless `close_goals = ff`
guard ¬ close_goals,
ng' ← num_goals,
return (ng - ng'))
/--
Apply the declaration `d` (or the forward and backward implications separately, if it is an `iff`),
and then attempt to solve the subgoal using `apply_and_solve`.
Returns the number of subgoals successfully closed.
-/
meta def apply_declaration (close_goals : bool) (opt : suggest_opt := { }) (d : decl_data) :
tactic ℕ :=
let tac := apply_and_solve close_goals opt in
do (e, t) ← decl_mk_const d.d,
match d.m with
| ex := tac e
| mp := do l ← iff_mp_core e t, tac l
| mpr := do l ← iff_mpr_core e t, tac l
| both := undefined -- we use `unpack_iff_both` to ensure this isn't reachable
end
/-- An `application` records the result of a successful application of a library lemma. -/
meta structure application :=
(state : tactic_state)
(script : string)
(decl : option declaration)
(num_goals : ℕ)
(hyps_used : list expr)
end suggest
open solve_by_elim
open suggest
declare_trace suggest -- Trace a list of all relevant lemmas
-- Call `apply_declaration`, then prepare the tactic script and
-- count the number of local hypotheses used.
private meta def apply_declaration_script
(g : expr) (hyps : list expr)
(opt : suggest_opt := { })
(d : decl_data) :
tactic application :=
-- (This tactic block is only executed when we evaluate the mllist,
-- so we need to do the `focus1` here.)
retrieve $ focus1 $ do
apply_declaration ff opt d,
-- This `instantiate_mvars` is necessary so that we count used hypotheses correctly.
g ← instantiate_mvars g,
guard $ (opt.compulsory_hyps.all (λ h, h.occurs g)),
ng ← num_goals,
s ← read,
m ← tactic_statement g,
return
{ application .
state := s,
decl := d.d,
script := m,
num_goals := ng,
hyps_used := hyps.filter (λ h, h.occurs g) }
-- implementation note: we produce a `tactic (mllist tactic application)` first,
-- because it's easier to work in the tactic monad, but in a moment we squash this
-- down to an `mllist tactic application`.
private meta def suggest_core' (opt : suggest_opt := { }) :
tactic (mllist tactic application) :=
do g :: _ ← get_goals,
hyps ← local_context,
-- Check if `solve_by_elim` can solve the goal immediately:
(retrieve (do
focus1 $ solve_by_elim opt.mk_accept,
s ← read,
m ← tactic_statement g,
-- This `instantiate_mvars` is necessary so that we count used hypotheses correctly.
g ← instantiate_mvars g,
guard (opt.compulsory_hyps.all (λ h, h.occurs g)),
return $ mllist.of_list [⟨s, m, none, 0, hyps.filter (λ h, h.occurs g)⟩])) <|>
-- Otherwise, let's actually try applying library lemmas.
(do
-- Collect all definitions with the correct head symbol
t ← infer_type g,
defs ← unpack_iff_both <$> library_defs (name_set.of_list $ allowed_head_symbols t),
let defs : mllist tactic _ := mllist.of_list defs,
-- Try applying each lemma against the goal,
-- recording the tactic script as a string,
-- the number of remaining goals,
-- and number of local hypotheses used.
let results := defs.mfilter_map (apply_declaration_script g hyps opt),
-- Now call `symmetry` and try again.
-- (Because we are using `mllist`, this is essentially free if we've already found a lemma.)
symm_state ← retrieve $ try_core $ symmetry >> read,
let results_symm := match symm_state with
| (some s) :=
defs.mfilter_map (λ d, retrieve $ set_state s >> apply_declaration_script g hyps opt d)
| none := mllist.nil
end,
return (results.append results_symm))
/--
The core `suggest` tactic.
It attempts to apply a declaration from the library,
then solve new goals using `solve_by_elim`.
It returns a list of `application`s consisting of fields:
* `state`, a tactic state resulting from the successful application of a declaration from
the library,
* `script`, a string of the form `Try this: refine ...` or `Try this: exact ...` which will
reproduce that tactic state,
* `decl`, an `option declaration` indicating the declaration that was applied
(or none, if `solve_by_elim` succeeded),
* `num_goals`, the number of remaining goals, and
* `hyps_used`, the number of local hypotheses used in the solution.
-/
meta def suggest_core (opt : suggest_opt := { }) : mllist tactic application :=
(mllist.monad_lift (suggest_core' opt)).join
/--
See `suggest_core`.
Returns a list of at most `limit` `application`s,
sorted by number of goals, and then (reverse) number of hypotheses used.
-/
meta def suggest (limit : option ℕ := none) (opt : suggest_opt := { }) :
tactic (list application) :=
do let results := suggest_core opt,
-- Get the first n elements of the successful lemmas
L ← if h : limit.is_some then results.take (option.get h) else results.force,
-- Sort by number of remaining goals, then by number of hypotheses used.
return $ L.qsort (λ d₁ d₂, d₁.num_goals < d₂.num_goals ∨
(d₁.num_goals = d₂.num_goals ∧ d₁.hyps_used.length ≥ d₂.hyps_used.length))
/--
Returns a list of at most `limit` strings, of the form `Try this: exact ...` or
`Try this: refine ...`, which make progress on the current goal using a declaration
from the library.
-/
meta def suggest_scripts
(limit : option ℕ := none) (opt : suggest_opt := { }) :
tactic (list string) :=
do L ← suggest limit opt,
return $ L.map application.script
/--
Returns a string of the form `Try this: exact ...`, which closes the current goal.
-/
meta def library_search (opt : suggest_opt := { }) : tactic string :=
(suggest_core opt).mfirst (λ a, do
guard (a.num_goals = 0),
write a.state,
return a.script)
namespace interactive
setup_tactic_parser
open solve_by_elim
declare_trace silence_suggest -- Turn off `Try this: exact/refine ...` trace messages for `suggest`
/--
`suggest` tries to apply suitable theorems/defs from the library, and generates
a list of `exact ...` or `refine ...` scripts that could be used at this step.
It leaves the tactic state unchanged. It is intended as a complement of the search
function in your editor, the `#find` tactic, and `library_search`.
`suggest` takes an optional natural number `num` as input and returns the first `num`
(or less, if all possibilities are exhausted) possibilities ordered by length of lemma names.
The default for `num` is `50`.
For performance reasons `suggest` uses monadic lazy lists (`mllist`). This means that
`suggest` might miss some results if `num` is not large enough. However, because
`suggest` uses monadic lazy lists, smaller values of `num` run faster than larger values.
You can add additional lemmas to be used along with local hypotheses
after the application of a library lemma,
using the same syntax as for `solve_by_elim`, e.g.
```
example {a b c d: nat} (h₁ : a < c) (h₂ : b < d) : max (c + d) (a + b) = (c + d) :=
begin
suggest [add_lt_add], -- Says: `Try this: exact max_eq_left_of_lt (add_lt_add h₁ h₂)`
end
```
You can also use `suggest with attr` to include all lemmas with the attribute `attr`.
-/
meta def suggest (n : parse (with_desc "n" small_nat)?)
(hs : parse simp_arg_list) (attr_names : parse with_ident_list)
(use : parse $ (tk "using" *> many ident_) <|> return []) (opt : opt := { }) :
tactic unit :=
do (lemma_thunks, ctx_thunk) ← mk_assumption_set ff hs attr_names,
use ← use.mmap get_local,
L ← tactic.suggest_scripts (n.get_or_else 50)
{ compulsory_hyps := use,
lemma_thunks := some lemma_thunks,
ctx_thunk := ctx_thunk, ..opt },
if is_trace_enabled_for `silence_suggest then
skip
else
if L.length = 0 then
fail "There are no applicable declarations"
else
L.mmap trace >> skip
/--
`suggest` lists possible usages of the `refine` tactic and leaves the tactic state unchanged.
It is intended as a complement of the search function in your editor, the `#find` tactic, and
`library_search`.
`suggest` takes an optional natural number `num` as input and returns the first `num` (or less, if
all possibilities are exhausted) possibilities ordered by length of lemma names.
The default for `num` is `50`.
`suggest using h₁ h₂` will only show solutions that make use of the local hypotheses `h₁` and `h₂`.
For performance reasons `suggest` uses monadic lazy lists (`mllist`). This means that `suggest`
might miss some results if `num` is not large enough. However, because `suggest` uses monadic
lazy lists, smaller values of `num` run faster than larger values.
An example of `suggest` in action,
```lean
example (n : nat) : n < n + 1 :=
begin suggest, sorry end
```
prints the list,
```lean
Try this: exact nat.lt.base n
Try this: exact nat.lt_succ_self n
Try this: refine not_le.mp _
Try this: refine gt_iff_lt.mp _
Try this: refine nat.lt.step _
Try this: refine lt_of_not_ge _
...
```
-/
add_tactic_doc
{ name := "suggest",
category := doc_category.tactic,
decl_names := [`tactic.interactive.suggest],
tags := ["search", "Try this"] }
-- Turn off `Try this: exact ...` trace message for `library_search`
declare_trace silence_library_search
/--
`library_search` is a tactic to identify existing lemmas in the library. It tries to close the
current goal by applying a lemma from the library, then discharging any new goals using
`solve_by_elim`.
If it succeeds, it prints a trace message `exact ...` which can replace the invocation
of `library_search`.
Typical usage is:
```lean
example (n m k : ℕ) : n * (m - k) = n * m - n * k :=
by library_search -- Try this: exact mul_tsub n m k
```
`library_search using h₁ h₂` will only show solutions
that make use of the local hypotheses `h₁` and `h₂`.
By default `library_search` only unfolds `reducible` definitions
when attempting to match lemmas against the goal.
Previously, it would unfold most definitions, sometimes giving surprising answers, or slow answers.
The old behaviour is still available via `library_search!`.
You can add additional lemmas to be used along with local hypotheses
after the application of a library lemma,
using the same syntax as for `solve_by_elim`, e.g.
```
example {a b c d: nat} (h₁ : a < c) (h₂ : b < d) : max (c + d) (a + b) = (c + d) :=
begin
library_search [add_lt_add], -- Says: `Try this: exact max_eq_left_of_lt (add_lt_add h₁ h₂)`
end
```
You can also use `library_search with attr` to include all lemmas with the attribute `attr`.
-/
meta def library_search (semireducible : parse $ optional (tk "!"))
(hs : parse simp_arg_list) (attr_names : parse with_ident_list)
(use : parse $ (tk "using" *> many ident_) <|> return [])
(opt : opt := { }) : tactic unit :=
do (lemma_thunks, ctx_thunk) ← mk_assumption_set ff hs attr_names,
use ← use.mmap get_local,
(tactic.library_search
{ compulsory_hyps := use,
backtrack_all_goals := tt,
lemma_thunks := some lemma_thunks,
ctx_thunk := ctx_thunk,
md := if semireducible.is_some then
tactic.transparency.semireducible else tactic.transparency.reducible,
..opt } >>=
if is_trace_enabled_for `silence_library_search then
(λ _, skip)
else
trace) <|>
fail
"`library_search` failed.
If you aren't sure what to do next, you can also
try `library_search!`, `suggest`, or `hint`.
Possible reasons why `library_search` failed:
* `library_search` will only apply a single lemma from the library,
and then try to fill in its hypotheses from local hypotheses.
* If you haven't already, try stating the theorem you want in its own lemma.
* Sometimes the library has one version of a lemma
but not a very similar version obtained by permuting arguments.
Try replacing `a + b` with `b + a`, or `a - b < c` with `a < b + c`,
to see if maybe the lemma exists but isn't stated quite the way you would like.
* Make sure that you have all the side conditions for your theorem to be true.
For example you won't find `a - b + b = a` for natural numbers in the library because it's false!
Search for `b ≤ a → a - b + b = a` instead.
* If a definition you made is in the goal,
you won't find any theorems about it in the library.
Try unfolding the definition using `unfold my_definition`.
* If all else fails, ask on https://leanprover.zulipchat.com/,
and maybe we can improve the library and/or `library_search` for next time."
add_tactic_doc
{ name := "library_search",
category := doc_category.tactic,
decl_names := [`tactic.interactive.library_search],
tags := ["search", "Try this"] }
end interactive
/-- Invoking the hole command `library_search` ("Use `library_search` to complete the goal") calls
the tactic `library_search` to produce a proof term with the type of the hole.
Running it on
```lean
example : 0 < 1 :=
{!!}
```
produces
```lean
example : 0 < 1 :=
nat.one_pos
```
-/
@[hole_command] meta def library_search_hole_cmd : hole_command :=
{ name := "library_search",
descr := "Use `library_search` to complete the goal.",
action := λ _, do
script ← library_search,
-- Is there a better API for dropping the 'Try this: exact ' prefix on this string?
return [((script.get_rest "Try this: exact ").get_or_else script, "by library_search")] }
add_tactic_doc
{ name := "library_search",
category := doc_category.hole_cmd,
decl_names := [`tactic.library_search_hole_cmd],
tags := ["search", "Try this"] }
end tactic
|
b56bfd2600ca65446a3296bb5ae3b5eb193f6951 | 491068d2ad28831e7dade8d6dff871c3e49d9431 | /tests/lean/unfoldf.lean | 95bd708db2e041e7c4159a9bd43f285b4b408d23 | [
"Apache-2.0"
] | permissive | davidmueller13/lean | 65a3ed141b4088cd0a268e4de80eb6778b21a0e9 | c626e2e3c6f3771e07c32e82ee5b9e030de5b050 | refs/heads/master | 1,611,278,313,401 | 1,444,021,177,000 | 1,444,021,177,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 481 | lean | open nat
definition id [unfold-full] {A : Type} (a : A) := a
definition compose {A B C : Type} (g : B → C) (f : A → B) (a : A) := g (f a)
notation g ∘ f := compose g f
example (a b : nat) (H : a = b) : id a = b :=
begin
esimp,
state,
exact H
end
example (a b : nat) (H : a = b) : (id ∘ id) a = b :=
begin
esimp,
state,
exact H
end
attribute compose [unfold-full]
example (a b : nat) (H : a = b) : (id ∘ id) a = b :=
begin
esimp,
state,
exact H
end
|
bc5de9caa3f8a507c11dc65ac8199fca8730b721 | 4efff1f47634ff19e2f786deadd394270a59ecd2 | /src/ring_theory/unique_factorization_domain.lean | 22b977fe326ff17c957f4200b1b931516e79ab9b | [
"Apache-2.0"
] | permissive | agjftucker/mathlib | d634cd0d5256b6325e3c55bb7fb2403548371707 | 87fe50de17b00af533f72a102d0adefe4a2285e8 | refs/heads/master | 1,625,378,131,941 | 1,599,166,526,000 | 1,599,166,526,000 | 160,748,509 | 0 | 0 | Apache-2.0 | 1,544,141,789,000 | 1,544,141,789,000 | null | UTF-8 | Lean | false | false | 23,114 | lean | /-
Copyright (c) 2018 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Jens Wagemaker
Theory of unique factorization domains.
@TODO: setup the complete lattice structure on `factor_set`.
-/
import algebra.gcd_monoid
import ring_theory.integral_domain
variables {α : Type*}
local infix ` ~ᵤ ` : 50 := associated
/-- Unique factorization domains.
In a unique factorization domain each element (except zero) is uniquely
represented as a multiset of irreducible factors.
Uniqueness is only up to associated elements.
This is equivalent to defining a unique factorization domain as a domain in
which each element (except zero) is non-uniquely represented as a multiset
of prime factors. This definition is used.
To define a UFD using the traditional definition in terms of multisets
of irreducible factors, use the definition `of_unique_irreducible_factorization`
-/
class unique_factorization_domain (α : Type*) [integral_domain α] :=
(factors : α → multiset α)
(factors_prod : ∀{a : α}, a ≠ 0 → (factors a).prod ~ᵤ a)
(prime_factors : ∀{a : α}, a ≠ 0 → ∀x∈factors a, prime x)
namespace unique_factorization_domain
variables [integral_domain α] [unique_factorization_domain α]
@[elab_as_eliminator] lemma induction_on_prime {P : α → Prop}
(a : α) (h₁ : P 0) (h₂ : ∀ x : α, is_unit x → P x)
(h₃ : ∀ a p : α, a ≠ 0 → prime p → P a → P (p * a)) : P a :=
by haveI := classical.dec_eq α; exact
if ha0 : a = 0 then ha0.symm ▸ h₁
else @multiset.induction_on _
(λ s : multiset α, ∀ (a : α), a ≠ 0 → s.prod ~ᵤ a → (∀ p ∈ s, prime p) → P a)
(factors a)
(λ _ _ h _, h₂ _ ((is_unit_iff_of_associated h.symm).2 is_unit_one))
(λ p s ih a ha0 ⟨u, hu⟩ hsp,
have ha : a = (p * u) * s.prod, by simp [hu.symm, mul_comm, mul_assoc],
have hs0 : s.prod ≠ 0, from λ _ : s.prod = 0, by simp * at *,
ha.symm ▸ h₃ _ _ hs0
(prime_of_associated ⟨u, rfl⟩ (hsp p (multiset.mem_cons_self _ _)))
(ih _ hs0 (by refl) (λ p hp, hsp p (multiset.mem_cons.2 (or.inr hp)))))
_
ha0
(factors_prod ha0)
(prime_factors ha0)
lemma factors_irreducible {a : α} (ha : irreducible a) :
∃ p, a ~ᵤ p ∧ factors a = p :: 0 :=
by haveI := classical.dec_eq α; exact
multiset.induction_on (factors a)
(λ h, (ha.1 (associated_one_iff_is_unit.1 h.symm)).elim)
(λ p s _ hp hs, let ⟨u, hu⟩ := hp in ⟨p,
have hs0 : s = 0, from classical.by_contradiction
(λ hs0, let ⟨q, hq⟩ := multiset.exists_mem_of_ne_zero hs0 in
(hs q (by simp [hq])).2.1 $
(ha.2 ((p * u) * (s.erase q).prod) _
(by rw [mul_right_comm _ _ q, mul_assoc, ← multiset.prod_cons,
multiset.cons_erase hq]; simp [hu.symm, mul_comm, mul_assoc])).resolve_left $
mt is_unit_of_mul_is_unit_left $ mt is_unit_of_mul_is_unit_left
(hs p (multiset.mem_cons_self _ _)).2.1),
⟨associated.symm (by clear _let_match; simp * at *), hs0 ▸ rfl⟩⟩)
(factors_prod ha.ne_zero)
(prime_factors ha.ne_zero)
lemma irreducible_iff_prime {p : α} : irreducible p ↔ prime p :=
by letI := classical.dec_eq α; exact
if hp0 : p = 0 then by simp [hp0]
else
⟨λ h, let ⟨q, hq⟩ := factors_irreducible h in
have prime q, from hq.2 ▸ prime_factors hp0 _ (by simp [hq.2]),
suffices prime (factors p).prod,
from prime_of_associated (factors_prod hp0) this,
hq.2.symm ▸ by simp [this],
irreducible_of_prime⟩
lemma irreducible_factors : ∀{a : α}, a ≠ 0 → ∀x∈factors a, irreducible x :=
by simp only [irreducible_iff_prime]; exact @prime_factors _ _ _
lemma unique : ∀{f g : multiset α},
(∀x∈f, irreducible x) → (∀x∈g, irreducible x) → f.prod ~ᵤ g.prod →
multiset.rel associated f g :=
by haveI := classical.dec_eq α; exact
λ f, multiset.induction_on f
(λ g _ hg h,
multiset.rel_zero_left.2 $
multiset.eq_zero_of_forall_not_mem (λ x hx,
have is_unit g.prod, by simpa [associated_one_iff_is_unit] using h.symm,
(hg x hx).1 (is_unit_iff_dvd_one.2 (dvd.trans (multiset.dvd_prod hx)
(is_unit_iff_dvd_one.1 this)))))
(λ p f ih g hf hg hfg,
let ⟨b, hbg, hb⟩ := exists_associated_mem_of_dvd_prod
(irreducible_iff_prime.1 (hf p (by simp)))
(λ q hq, irreducible_iff_prime.1 (hg _ hq)) $
(dvd_iff_dvd_of_rel_right hfg).1
(show p ∣ (p :: f).prod, by simp) in
begin
rw ← multiset.cons_erase hbg,
exact multiset.rel.cons hb (ih (λ q hq, hf _ (by simp [hq]))
(λ q (hq : q ∈ g.erase b), hg q (multiset.mem_of_mem_erase hq))
(associated_mul_left_cancel
(by rwa [← multiset.prod_cons, ← multiset.prod_cons, multiset.cons_erase hbg]) hb
(hf p (by simp)).ne_zero))
end)
end unique_factorization_domain
structure unique_irreducible_factorization (α : Type*) [integral_domain α] :=
(factors : α → multiset α)
(factors_prod : ∀{a : α}, a ≠ 0 → (factors a).prod ~ᵤ a)
(irreducible_factors : ∀{a : α}, a ≠ 0 → ∀x∈factors a, irreducible x)
(unique : ∀{f g : multiset α},
(∀x∈f, irreducible x) → (∀x∈g, irreducible x) → f.prod ~ᵤ g.prod → multiset.rel associated f g)
namespace unique_factorization_domain
open unique_factorization_domain associated
variables [integral_domain α] [unique_factorization_domain α]
lemma exists_mem_factors_of_dvd {a p : α} (ha0 : a ≠ 0) (hp : irreducible p) : p ∣ a →
∃ q ∈ factors a, p ~ᵤ q :=
λ ⟨b, hb⟩,
have hb0 : b ≠ 0, from λ hb0, by simp * at *,
have multiset.rel associated (p :: factors b) (factors a),
from unique
(λ x hx, (multiset.mem_cons.1 hx).elim (λ h, h.symm ▸ hp)
(irreducible_factors hb0 _))
(irreducible_factors ha0)
(associated.symm $ calc multiset.prod (factors a) ~ᵤ a : factors_prod ha0
... = p * b : hb
... ~ᵤ multiset.prod (p :: factors b) :
by rw multiset.prod_cons; exact associated_mul_mul
(associated.refl _)
(associated.symm (factors_prod hb0))),
multiset.exists_mem_of_rel_of_mem this (by simp)
def of_unique_irreducible_factorization {α : Type*} [integral_domain α]
(o : unique_irreducible_factorization α) : unique_factorization_domain α :=
{ prime_factors := by letI := classical.dec_eq α; exact λ a h p (hpa : p ∈ o.factors a),
have hpi : irreducible p, from o.irreducible_factors h _ hpa,
⟨hpi.ne_zero, hpi.1,
λ a b ⟨x, hx⟩,
if hab0 : a * b = 0
then (eq_zero_or_eq_zero_of_mul_eq_zero hab0).elim
(λ ha0, by simp [ha0])
(λ hb0, by simp [hb0])
else
have hx0 : x ≠ 0, from λ hx0, by simp * at *,
have ha0 : a ≠ 0, from left_ne_zero_of_mul hab0,
have hb0 : b ≠ 0, from right_ne_zero_of_mul hab0,
have multiset.rel associated (p :: o.factors x) (o.factors a + o.factors b),
from o.unique
(λ i hi, (multiset.mem_cons.1 hi).elim
(λ hip, hip.symm ▸ hpi)
(o.irreducible_factors hx0 _))
(show ∀ x ∈ o.factors a + o.factors b, irreducible x,
from λ x hx, (multiset.mem_add.1 hx).elim
(o.irreducible_factors ha0 _)
(o.irreducible_factors hb0 _)) $
calc multiset.prod (p :: o.factors x)
~ᵤ a * b : by rw [hx, multiset.prod_cons];
exact associated_mul_mul (by refl)
(o.factors_prod hx0)
... ~ᵤ (o.factors a).prod * (o.factors b).prod :
associated_mul_mul
(o.factors_prod ha0).symm
(o.factors_prod hb0).symm
... = _ : by rw multiset.prod_add,
let ⟨q, hqf, hq⟩ := multiset.exists_mem_of_rel_of_mem this
(multiset.mem_cons_self p _) in
(multiset.mem_add.1 hqf).elim
(λ hqa, or.inl $ (dvd_iff_dvd_of_rel_left hq).2 $
(dvd_iff_dvd_of_rel_right (o.factors_prod ha0)).1
(multiset.dvd_prod hqa))
(λ hqb, or.inr $ (dvd_iff_dvd_of_rel_left hq).2 $
(dvd_iff_dvd_of_rel_right (o.factors_prod hb0)).1
(multiset.dvd_prod hqb))⟩,
..o }
end unique_factorization_domain
namespace associates
open unique_factorization_domain associated
variables [integral_domain α]
/-- `factor_set α` representation elements of unique factorization domain as multisets.
`multiset α` produced by `factors` are only unique up to associated elements, while the multisets in
`factor_set α` are unqiue by equality and restricted to irreducible elements. This gives us a
representation of each element as a unique multisets (or the added ⊤ for 0), which has a complete
lattice struture. Infimum is the greatest common divisor and supremum is the least common multiple.
-/
@[reducible] def {u} factor_set (α : Type u) [integral_domain α] :
Type u :=
with_top (multiset { a : associates α // irreducible a })
local attribute [instance] associated.setoid
theorem factor_set.coe_add {a b : multiset { a : associates α // irreducible a }} :
(↑(a + b) : factor_set α) = a + b :=
by norm_cast
lemma factor_set.sup_add_inf_eq_add [decidable_eq (associates α)] :
∀(a b : factor_set α), a ⊔ b + a ⊓ b = a + b
| none b := show ⊤ ⊔ b + ⊤ ⊓ b = ⊤ + b, by simp
| a none := show a ⊔ ⊤ + a ⊓ ⊤ = a + ⊤, by simp
| (some a) (some b) := show (a : factor_set α) ⊔ b + a ⊓ b = a + b, from
begin
rw [← with_top.coe_sup, ← with_top.coe_inf, ← with_top.coe_add, ← with_top.coe_add,
with_top.coe_eq_coe],
exact multiset.union_add_inter _ _
end
def factor_set.prod : factor_set α → associates α
| none := 0
| (some s) := (s.map coe).prod
@[simp] theorem prod_top : (⊤ : factor_set α).prod = 0 := rfl
@[simp] theorem prod_coe {s : multiset { a : associates α // irreducible a }} :
(s : factor_set α).prod = (s.map coe).prod :=
rfl
@[simp] theorem prod_add : ∀(a b : factor_set α), (a + b).prod = a.prod * b.prod
| none b := show (⊤ + b).prod = (⊤:factor_set α).prod * b.prod, by simp
| a none := show (a + ⊤).prod = a.prod * (⊤:factor_set α).prod, by simp
| (some a) (some b) :=
show (↑a + ↑b:factor_set α).prod = (↑a:factor_set α).prod * (↑b:factor_set α).prod,
by rw [← factor_set.coe_add, prod_coe, prod_coe, prod_coe, multiset.map_add, multiset.prod_add]
theorem prod_mono : ∀{a b : factor_set α}, a ≤ b → a.prod ≤ b.prod
| none b h := have b = ⊤, from top_unique h, by rw [this, prod_top]; exact le_refl _
| a none h := show a.prod ≤ (⊤ : factor_set α).prod, by simp; exact le_top
| (some a) (some b) h := prod_le_prod $ multiset.map_le_map $ with_top.coe_le_coe.1 $ h
variable [unique_factorization_domain α]
theorem unique' {p q : multiset (associates α)} :
(∀a∈p, irreducible a) → (∀a∈q, irreducible a) → p.prod = q.prod → p = q :=
begin
apply multiset.induction_on_multiset_quot p,
apply multiset.induction_on_multiset_quot q,
assume s t hs ht eq,
refine multiset.map_mk_eq_map_mk_of_rel (unique_factorization_domain.unique _ _ _),
{ exact assume a ha, ((irreducible_mk_iff _).1 $ hs _ $ multiset.mem_map_of_mem _ ha) },
{ exact assume a ha, ((irreducible_mk_iff _).1 $ ht _ $ multiset.mem_map_of_mem _ ha) },
simpa [quot_mk_eq_mk, prod_mk, mk_eq_mk_iff_associated] using eq
end
private theorem forall_map_mk_factors_irreducible (x : α) (hx : x ≠ 0) :
∀(a : associates α), a ∈ multiset.map associates.mk (factors x) → irreducible a :=
begin
assume a ha,
rcases multiset.mem_map.1 ha with ⟨c, hc, rfl⟩,
exact (irreducible_mk_iff c).2 (irreducible_factors hx _ hc)
end
theorem prod_le_prod_iff_le {p q : multiset (associates α)}
(hp : ∀a∈p, irreducible a) (hq : ∀a∈q, irreducible a) :
p.prod ≤ q.prod ↔ p ≤ q :=
iff.intro
begin
rintros ⟨⟨c⟩, eqc⟩,
have : c ≠ 0, from (mt mk_eq_zero.2 $
assume (hc : quot.mk setoid.r c = 0),
have (0 : associates α) ∈ q, from prod_eq_zero_iff.1 $ eqc.symm ▸ hc.symm ▸ mul_zero _,
not_irreducible_zero ((irreducible_mk_iff 0).1 $ hq _ this)),
have : associates.mk (factors c).prod = quot.mk setoid.r c,
from mk_eq_mk_iff_associated.2 (factors_prod this),
refine le_iff_exists_add.2 ⟨(factors c).map associates.mk, unique' hq _ _⟩,
{ assume x hx,
rcases multiset.mem_add.1 hx with h | h,
exact hp x h,
exact forall_map_mk_factors_irreducible c ‹c ≠ 0› _ h },
{ simp [multiset.prod_add, prod_mk, *] at * }
end
prod_le_prod
def factors' (a : α) (ha : a ≠ 0) : multiset { a : associates α // irreducible a } :=
(factors a).pmap (λa ha, ⟨associates.mk a, (irreducible_mk_iff _).2 ha⟩)
(irreducible_factors $ ha)
@[simp] theorem map_subtype_coe_factors' {a : α} (ha : a ≠ 0) :
(factors' a ha).map coe = (factors a).map associates.mk :=
by simp [factors', multiset.map_pmap, multiset.pmap_eq_map]
theorem factors'_cong {a b : α} (ha : a ≠ 0) (hb : b ≠ 0) (h : a ~ᵤ b) :
factors' a ha = factors' b hb :=
have multiset.rel associated (factors a) (factors b), from
unique (irreducible_factors ha) (irreducible_factors hb)
((factors_prod ha).trans $ h.trans $ (factors_prod hb).symm),
by simpa [(multiset.map_eq_map subtype.coe_injective).symm, rel_associated_iff_map_eq_map.symm]
variable [dec : decidable_eq (associates α)]
include dec
def factors (a : associates α) : factor_set α :=
begin
refine (if h : a = 0 then ⊤ else
quotient.hrec_on a (λx h, some $ factors' x (mt mk_eq_zero.2 h)) _ h),
assume a b hab,
apply function.hfunext,
{ have : a ~ᵤ 0 ↔ b ~ᵤ 0, from
iff.intro (assume ha0, hab.symm.trans ha0) (assume hb0, hab.trans hb0),
simp only [associated_zero_iff_eq_zero] at this,
simp only [quotient_mk_eq_mk, this, mk_eq_zero] },
exact (assume ha hb eq, heq_of_eq $ congr_arg some $ factors'_cong _ _ hab)
end
@[simp] theorem factors_0 : (0 : associates α).factors = ⊤ :=
dif_pos rfl
@[simp] theorem factors_mk (a : α) (h : a ≠ 0) : (associates.mk a).factors = factors' a h :=
dif_neg (mt mk_eq_zero.1 h)
theorem prod_factors : ∀(s : factor_set α), s.prod.factors = s
| none := by simp [factor_set.prod]; refl
| (some s) :=
begin
unfold factor_set.prod,
generalize eq_a : (s.map coe).prod = a,
rcases a with ⟨a⟩,
rw quot_mk_eq_mk at *,
have : (s.map (coe : _ → associates α)).prod ≠ 0, from assume ha,
let ⟨⟨a, ha⟩, h, eq⟩ := multiset.mem_map.1 (prod_eq_zero_iff.1 ha) in
have irreducible (0 : associates α), from eq ▸ ha,
not_irreducible_zero ((irreducible_mk_iff _).1 this),
have ha : a ≠ 0, by simp [*] at *,
suffices : (unique_factorization_domain.factors a).map associates.mk = s.map coe,
{ rw [factors_mk a ha],
apply congr_arg some _,
simpa [(multiset.map_eq_map subtype.coe_injective).symm] },
refine unique'
(forall_map_mk_factors_irreducible _ ha)
(assume a ha, let ⟨⟨x, hx⟩, ha, eq⟩ := multiset.mem_map.1 ha in eq ▸ hx)
_,
rw [prod_mk, eq_a, mk_eq_mk_iff_associated],
exact factors_prod ha
end
theorem factors_prod (a : associates α) : a.factors.prod = a :=
quotient.induction_on a $ assume a, decidable.by_cases
(assume : associates.mk a = 0, by simp [quotient_mk_eq_mk, this])
(assume : associates.mk a ≠ 0,
have a ≠ 0, by simp * at *,
by simp [this, quotient_mk_eq_mk, prod_mk, mk_eq_mk_iff_associated.2 (factors_prod this)])
theorem eq_of_factors_eq_factors {a b : associates α} (h : a.factors = b.factors) : a = b :=
have a.factors.prod = b.factors.prod, by rw h,
by rwa [factors_prod, factors_prod] at this
omit dec
theorem eq_of_prod_eq_prod {a b : factor_set α} (h : a.prod = b.prod) : a = b :=
begin
classical,
have : a.prod.factors = b.prod.factors, by rw h,
rwa [prod_factors, prod_factors] at this
end
include dec
@[simp] theorem factors_mul (a b : associates α) : (a * b).factors = a.factors + b.factors :=
eq_of_prod_eq_prod $ eq_of_factors_eq_factors $
by rw [prod_add, factors_prod, factors_prod, factors_prod]
theorem factors_mono : ∀{a b : associates α}, a ≤ b → a.factors ≤ b.factors
| s t ⟨d, rfl⟩ := by rw [factors_mul] ; exact le_add_of_nonneg_right bot_le
theorem factors_le {a b : associates α} : a.factors ≤ b.factors ↔ a ≤ b :=
iff.intro
(assume h, have a.factors.prod ≤ b.factors.prod, from prod_mono h,
by rwa [factors_prod, factors_prod] at this)
factors_mono
omit dec
theorem prod_le {a b : factor_set α} : a.prod ≤ b.prod ↔ a ≤ b :=
begin
classical,
exact iff.intro
(assume h, have a.prod.factors ≤ b.prod.factors, from factors_mono h,
by rwa [prod_factors, prod_factors] at this)
prod_mono
end
include dec
instance : has_sup (associates α) := ⟨λa b, (a.factors ⊔ b.factors).prod⟩
instance : has_inf (associates α) := ⟨λa b, (a.factors ⊓ b.factors).prod⟩
instance : bounded_lattice (associates α) :=
{ sup := (⊔),
inf := (⊓),
sup_le :=
assume a b c hac hbc, factors_prod c ▸ prod_mono (sup_le (factors_mono hac) (factors_mono hbc)),
le_sup_left := assume a b,
le_trans (le_of_eq (factors_prod a).symm) $ prod_mono $ le_sup_left,
le_sup_right := assume a b,
le_trans (le_of_eq (factors_prod b).symm) $ prod_mono $ le_sup_right,
le_inf :=
assume a b c hac hbc, factors_prod a ▸ prod_mono (le_inf (factors_mono hac) (factors_mono hbc)),
inf_le_left := assume a b,
le_trans (prod_mono inf_le_left) (le_of_eq (factors_prod a)),
inf_le_right := assume a b,
le_trans (prod_mono inf_le_right) (le_of_eq (factors_prod b)),
.. associates.partial_order,
.. associates.order_top,
.. associates.order_bot }
lemma sup_mul_inf (a b : associates α) : (a ⊔ b) * (a ⊓ b) = a * b :=
show (a.factors ⊔ b.factors).prod * (a.factors ⊓ b.factors).prod = a * b,
begin
refine eq_of_factors_eq_factors _,
rw [← prod_add, prod_factors, factors_mul, factor_set.sup_add_inf_eq_add]
end
end associates
section
open associates unique_factorization_domain
/-- `to_gcd_monoid` constructs a GCD monoid out of a normalization on a
unique factorization domain. -/
def unique_factorization_domain.to_gcd_monoid
(α : Type*) [integral_domain α] [unique_factorization_domain α] [normalization_monoid α]
[decidable_eq (associates α)] : gcd_monoid α :=
{ gcd := λa b, (associates.mk a ⊓ associates.mk b).out,
lcm := λa b, (associates.mk a ⊔ associates.mk b).out,
gcd_dvd_left := assume a b, (out_dvd_iff a (associates.mk a ⊓ associates.mk b)).2 $ inf_le_left,
gcd_dvd_right := assume a b, (out_dvd_iff b (associates.mk a ⊓ associates.mk b)).2 $ inf_le_right,
dvd_gcd := assume a b c hac hab, show a ∣ (associates.mk c ⊓ associates.mk b).out,
by rw [dvd_out_iff, le_inf_iff, mk_le_mk_iff_dvd_iff, mk_le_mk_iff_dvd_iff]; exact ⟨hac, hab⟩,
lcm_zero_left := assume a, show (⊤ ⊔ associates.mk a).out = 0, by simp,
lcm_zero_right := assume a, show (associates.mk a ⊔ ⊤).out = 0, by simp,
gcd_mul_lcm := assume a b,
show (associates.mk a ⊓ associates.mk b).out * (associates.mk a ⊔ associates.mk b).out =
normalize (a * b),
by rw [← out_mk, ← out_mul, mul_comm, sup_mul_inf]; refl,
normalize_gcd := assume a b, by convert normalize_out _,
.. ‹normalization_monoid α› }
end
namespace unique_factorization_domain
variables {R : Type*} [integral_domain R] [unique_factorization_domain R]
lemma no_factors_of_no_prime_factors {a b : R} (ha : a ≠ 0)
(h : (∀ {d}, d ∣ a → d ∣ b → ¬ prime d)) : ∀ {d}, d ∣ a → d ∣ b → is_unit d :=
λ d, induction_on_prime d
(by { simp only [zero_dvd_iff], intros, contradiction })
(λ x hx _ _, hx)
(λ d q hp hq ih dvd_a dvd_b,
absurd hq (h (dvd_of_mul_right_dvd dvd_a) (dvd_of_mul_right_dvd dvd_b)))
/-- Euclid's lemma: if `a ∣ b * c` and `a` and `c` have no common prime factors, `a ∣ b`.
Compare `is_coprime.dvd_of_dvd_mul_left`. -/
lemma dvd_of_dvd_mul_left_of_no_prime_factors {a b c : R} (ha : a ≠ 0) :
(∀ {d}, d ∣ a → d ∣ c → ¬ prime d) → a ∣ b * c → a ∣ b :=
begin
refine induction_on_prime c _ _ _,
{ intro no_factors,
simp only [dvd_zero, mul_zero, forall_prop_of_true],
haveI := classical.prop_decidable,
exact is_unit_iff_forall_dvd.mp
(no_factors_of_no_prime_factors ha @no_factors (dvd_refl a) (dvd_zero a)) _ },
{ rintros _ ⟨x, rfl⟩ _ a_dvd_bx,
apply units.dvd_mul_right.mp a_dvd_bx },
{ intros c p hc hp ih no_factors a_dvd_bpc,
apply ih (λ q dvd_a dvd_c hq, no_factors dvd_a (dvd_mul_of_dvd_right dvd_c _) hq),
rw mul_left_comm at a_dvd_bpc,
refine or.resolve_left (left_dvd_or_dvd_right_of_dvd_prime_mul hp a_dvd_bpc) (λ h, _),
exact no_factors h (dvd_mul_right p c) hp }
end
/-- Euclid's lemma: if `a ∣ b * c` and `a` and `b` have no common prime factors, `a ∣ c`.
Compare `is_coprime.dvd_of_dvd_mul_right`. -/
lemma dvd_of_dvd_mul_right_of_no_prime_factors {a b c : R} (ha : a ≠ 0)
(no_factors : ∀ {d}, d ∣ a → d ∣ b → ¬ prime d) : a ∣ b * c → a ∣ c :=
by simpa [mul_comm b c] using dvd_of_dvd_mul_left_of_no_prime_factors ha @no_factors
/-- If `a ≠ 0, b` are elements of a unique factorization domain, then dividing
out their common factor `c'` gives `a'` and `b'` with no factors in common. -/
lemma exists_reduced_factors : ∀ (a ≠ (0 : R)) b,
∃ a' b' c', (∀ {d}, d ∣ a' → d ∣ b' → is_unit d) ∧ c' * a' = a ∧ c' * b' = b :=
begin
haveI := classical.prop_decidable,
intros a,
refine induction_on_prime a _ _ _,
{ intros, contradiction },
{ intros a a_unit a_ne_zero b,
use [a, b, 1],
split,
{ intros p p_dvd_a _,
exact is_unit_of_dvd_unit p_dvd_a a_unit },
{ simp } },
{ intros a p a_ne_zero p_prime ih_a pa_ne_zero b,
by_cases p ∣ b,
{ rcases h with ⟨b, rfl⟩,
obtain ⟨a', b', c', no_factor, ha', hb'⟩ := ih_a a_ne_zero b,
refine ⟨a', b', p * c', @no_factor, _, _⟩,
{ rw [mul_assoc, ha'] },
{ rw [mul_assoc, hb'] } },
{ obtain ⟨a', b', c', coprime, rfl, rfl⟩ := ih_a a_ne_zero b,
refine ⟨p * a', b', c', _, mul_left_comm _ _ _, rfl⟩,
intros q q_dvd_pa' q_dvd_b',
cases left_dvd_or_dvd_right_of_dvd_prime_mul p_prime q_dvd_pa' with p_dvd_q q_dvd_a',
{ have : p ∣ c' * b' := dvd_mul_of_dvd_right (dvd_trans p_dvd_q q_dvd_b') _,
contradiction },
exact coprime q_dvd_a' q_dvd_b' } }
end
lemma exists_reduced_factors' (a b : R) (hb : b ≠ 0) :
∃ a' b' c', (∀ {d}, d ∣ a' → d ∣ b' → is_unit d) ∧ c' * a' = a ∧ c' * b' = b :=
let ⟨b', a', c', no_factor, hb, ha⟩ := exists_reduced_factors b hb a
in ⟨a', b', c', λ _ hpb hpa, no_factor hpa hpb, ha, hb⟩
end unique_factorization_domain
|
4d57eba7b4fbb555aee5deaa909a3fdc9009e52c | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/deprecated/ring.lean | c3df8ff072fb5d6564d46f653797813b9a48250d | [
"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 | 4,654 | lean | /-
Copyright (c) 2020 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
-/
import deprecated.group
/-!
# Unbundled semiring and ring homomorphisms (deprecated)
This file defines typeclasses for unbundled semiring and ring homomorphisms. Though these classes
are deprecated, they are still widely used in mathlib, and probably will not go away before Lean 4
because Lean 3 often fails to coerce a bundled homomorphism to a function.
## main definitions
is_semiring_hom (deprecated), is_ring_hom (deprecated)
## Tags
is_semiring_hom, is_ring_hom
-/
universes u v w
variable {α : Type u}
/-- Predicate for semiring homomorphisms (deprecated -- use the bundled `ring_hom` version). -/
class is_semiring_hom {α : Type u} {β : Type v} [semiring α] [semiring β] (f : α → β) : Prop :=
(map_zero [] : f 0 = 0)
(map_one [] : f 1 = 1)
(map_add [] : ∀ {x y}, f (x + y) = f x + f y)
(map_mul [] : ∀ {x y}, f (x * y) = f x * f y)
namespace is_semiring_hom
variables {β : Type v} [semiring α] [semiring β]
variables (f : α → β) [is_semiring_hom f] {x y : α}
/-- The identity map is a semiring homomorphism. -/
instance id : is_semiring_hom (@id α) := by refine {..}; intros; refl
/-- The composition of two semiring homomorphisms is a semiring homomorphism. -/
-- see Note [no instance on morphisms]
lemma comp {γ} [semiring γ] (g : β → γ) [is_semiring_hom g] :
is_semiring_hom (g ∘ f) :=
{ map_zero := by simp [map_zero f]; exact map_zero g,
map_one := by simp [map_one f]; exact map_one g,
map_add := λ x y, by simp [map_add f]; rw map_add g; refl,
map_mul := λ x y, by simp [map_mul f]; rw map_mul g; refl }
/-- A semiring homomorphism is an additive monoid homomorphism. -/
@[priority 100] -- see Note [lower instance priority]
instance : is_add_monoid_hom f :=
{ ..‹is_semiring_hom f› }
/-- A semiring homomorphism is a monoid homomorphism. -/
@[priority 100] -- see Note [lower instance priority]
instance : is_monoid_hom f :=
{ ..‹is_semiring_hom f› }
end is_semiring_hom
/-- Predicate for ring homomorphisms (deprecated -- use the bundled `ring_hom` version). -/
class is_ring_hom {α : Type u} {β : Type v} [ring α] [ring β] (f : α → β) : Prop :=
(map_one [] : f 1 = 1)
(map_mul [] : ∀ {x y}, f (x * y) = f x * f y)
(map_add [] : ∀ {x y}, f (x + y) = f x + f y)
namespace is_ring_hom
variables {β : Type v} [ring α] [ring β]
/-- A map of rings that is a semiring homomorphism is also a ring homomorphism. -/
lemma of_semiring (f : α → β) [H : is_semiring_hom f] : is_ring_hom f := {..H}
variables (f : α → β) [is_ring_hom f] {x y : α}
/-- Ring homomorphisms map zero to zero. -/
lemma map_zero : f 0 = 0 :=
calc f 0 = f (0 + 0) - f 0 : by rw [map_add f]; simp
... = 0 : by simp
/-- Ring homomorphisms preserve additive inverses. -/
lemma map_neg : f (-x) = -f x :=
calc f (-x) = f (-x + x) - f x : by rw [map_add f]; simp
... = -f x : by simp [map_zero f]
/-- Ring homomorphisms preserve subtraction. -/
lemma map_sub : f (x - y) = f x - f y :=
by simp [sub_eq_add_neg, map_add f, map_neg f]
/-- The identity map is a ring homomorphism. -/
instance id : is_ring_hom (@id α) := by refine {..}; intros; refl
/-- The composition of two ring homomorphisms is a ring homomorphism. -/
-- see Note [no instance on morphisms]
lemma comp {γ} [ring γ] (g : β → γ) [is_ring_hom g] :
is_ring_hom (g ∘ f) :=
{ map_add := λ x y, by simp [map_add f]; rw map_add g; refl,
map_mul := λ x y, by simp [map_mul f]; rw map_mul g; refl,
map_one := by simp [map_one f]; exact map_one g }
/-- A ring homomorphism is also a semiring homomorphism. -/
@[priority 100] -- see Note [lower instance priority]
instance : is_semiring_hom f :=
{ map_zero := map_zero f, ..‹is_ring_hom f› }
@[priority 100] -- see Note [lower instance priority]
instance : is_add_group_hom f := { }
end is_ring_hom
variables {β : Type v} {γ : Type w} [rα : semiring α] [rβ : semiring β]
namespace ring_hom
section
include rα rβ
/-- Interpret `f : α → β` with `is_semiring_hom f` as a ring homomorphism. -/
def of (f : α → β) [is_semiring_hom f] : α →+* β :=
{ to_fun := f,
.. monoid_hom.of f,
.. add_monoid_hom.of f }
@[simp] lemma coe_of (f : α → β) [is_semiring_hom f] : ⇑(of f) = f := rfl
instance (f : α →+* β) : is_semiring_hom f :=
{ map_zero := f.map_zero,
map_one := f.map_one,
map_add := f.map_add,
map_mul := f.map_mul }
end
instance {α γ} [ring α] [ring γ] (g : α →+* γ) : is_ring_hom g :=
is_ring_hom.of_semiring g
end ring_hom
|
fc187726ef2f771eba94f15d2555e72f20ad38cb | b7f22e51856f4989b970961f794f1c435f9b8f78 | /hott/algebra/category/constructions/set.hlean | fc51ac1bc0253af70b45d2a67a2220153f6dc0b0 | [
"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 | 3,572 | 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
Category of sets
-/
import ..functor.basic ..category types.equiv types.lift
open eq category equiv iso is_equiv is_trunc function sigma
namespace category
definition precategory_Set.{u} [reducible] [constructor] : precategory Set.{u} :=
precategory.mk (λx y : Set, x → y)
(λx y z g f a, g (f a))
(λx a, a)
(λx y z w h g f, eq_of_homotopy (λa, idp))
(λx y f, eq_of_homotopy (λa, idp))
(λx y f, eq_of_homotopy (λa, idp))
definition Precategory_Set [reducible] [constructor] : Precategory :=
Precategory.mk Set precategory_Set
abbreviation set [constructor] := Precategory_Set
namespace set
local attribute is_equiv_subtype_eq [instance]
definition iso_of_equiv [constructor] {A B : set} (f : A ≃ B) : A ≅ B :=
iso.MK (to_fun f)
(to_inv f)
(eq_of_homotopy (left_inv (to_fun f)))
(eq_of_homotopy (right_inv (to_fun f)))
definition equiv_of_iso [constructor] {A B : set} (f : A ≅ B) : A ≃ B :=
begin
apply equiv.MK (to_hom f) (iso.to_inv f),
exact ap10 (to_right_inverse f),
exact ap10 (to_left_inverse f)
end
definition is_equiv_iso_of_equiv [constructor] (A B : set)
: is_equiv (@iso_of_equiv A B) :=
adjointify _ (λf, equiv_of_iso f)
(λf, proof iso_eq idp qed)
(λf, equiv_eq' idp)
local attribute is_equiv_iso_of_equiv [instance]
definition iso_of_eq_eq_compose (A B : Set) : @iso_of_eq _ _ A B =
@iso_of_equiv A B ∘ @equiv_of_eq A B ∘ subtype_eq_inv _ _ ∘
@ap _ _ (to_fun (trunctype.sigma_char 0)) A B :=
eq_of_homotopy (λp, eq.rec_on p idp)
definition equiv_equiv_iso (A B : set) : (A ≃ B) ≃ (A ≅ B) :=
equiv.MK (λf, iso_of_equiv f)
(λf, proof equiv.MK (to_hom f)
(iso.to_inv f)
(ap10 (to_right_inverse f))
(ap10 (to_left_inverse f)) qed)
(λf, proof iso_eq idp qed)
(λf, proof equiv_eq' idp qed)
definition equiv_eq_iso (A B : set) : (A ≃ B) = (A ≅ B) :=
ua !equiv_equiv_iso
definition is_univalent_Set (A B : set) : is_equiv (iso_of_eq : A = B → A ≅ B) :=
have H₁ : is_equiv (@iso_of_equiv A B ∘ @equiv_of_eq A B ∘ subtype_eq_inv _ _ ∘
@ap _ _ (to_fun (trunctype.sigma_char 0)) A B), from
@is_equiv_compose _ _ _ _ _
(@is_equiv_compose _ _ _ _ _
(@is_equiv_compose _ _ _ _ _
_
(@is_equiv_subtype_eq_inv _ _ _ _ _))
!univalence)
!is_equiv_iso_of_equiv,
let H₂ := (iso_of_eq_eq_compose A B)⁻¹ in
begin
rewrite H₂ at H₁,
assumption
end
end set
definition category_Set [instance] [constructor] : category Set :=
category.mk precategory_Set set.is_univalent_Set
definition Category_Set [reducible] [constructor] : Category :=
Category.mk Set category_Set
abbreviation cset [constructor] := Category_Set
open functor lift
definition functor_lift.{u v} [constructor] : set.{u} ⇒ set.{max u v} :=
functor.mk tlift
(λa b, lift_functor)
(λa, eq_of_homotopy (λx, by induction x; reflexivity))
(λa b c g f, eq_of_homotopy (λx, by induction x; reflexivity))
end category
|
e47dfcaf3f2d77432a1513ca72b55e1c34e11c25 | 649957717d58c43b5d8d200da34bf374293fe739 | /src/algebra/archimedean.lean | 88caa3bc9c3bbe3a28e2188679359830b2a8715c | [
"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 | 15,761 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
Archimedean groups and fields.
-/
import algebra.group_power algebra.field_power
import data.rat.basic tactic.linarith tactic.abel
local infix ` • ` := add_monoid.smul
variables {α : Type*}
class floor_ring (α) [linear_ordered_ring α] :=
(floor : α → ℤ)
(le_floor : ∀ (z : ℤ) (x : α), z ≤ floor x ↔ (z : α) ≤ x)
instance : floor_ring ℤ :=
{ floor := id, le_floor := λ _ _, by rw int.cast_id; refl }
instance : floor_ring ℚ :=
{ floor := rat.floor, le_floor := @rat.le_floor }
section
variables [linear_ordered_ring α] [floor_ring α]
def floor : α → ℤ := floor_ring.floor
notation `⌊` x `⌋` := floor x
theorem le_floor : ∀ {z : ℤ} {x : α}, z ≤ ⌊x⌋ ↔ (z : α) ≤ x :=
floor_ring.le_floor
theorem floor_lt {x : α} {z : ℤ} : ⌊x⌋ < z ↔ x < z :=
lt_iff_lt_of_le_iff_le le_floor
theorem floor_le (x : α) : (⌊x⌋ : α) ≤ x :=
le_floor.1 (le_refl _)
theorem floor_nonneg {x : α} : 0 ≤ ⌊x⌋ ↔ 0 ≤ x :=
by rw [le_floor]; refl
theorem lt_succ_floor (x : α) : x < ⌊x⌋.succ :=
floor_lt.1 $ int.lt_succ_self _
theorem lt_floor_add_one (x : α) : x < ⌊x⌋ + 1 :=
by simpa only [int.succ, int.cast_add, int.cast_one] using lt_succ_floor x
theorem sub_one_lt_floor (x : α) : x - 1 < ⌊x⌋ :=
sub_lt_iff_lt_add.2 (lt_floor_add_one x)
@[simp] theorem floor_coe (z : ℤ) : ⌊(z:α)⌋ = z :=
eq_of_forall_le_iff $ λ a, by rw [le_floor, int.cast_le]
@[simp] theorem floor_zero : ⌊(0:α)⌋ = 0 := floor_coe 0
@[simp] theorem floor_one : ⌊(1:α)⌋ = 1 :=
by rw [← int.cast_one, floor_coe]
theorem floor_mono {a b : α} (h : a ≤ b) : ⌊a⌋ ≤ ⌊b⌋ :=
le_floor.2 (le_trans (floor_le _) h)
@[simp] theorem floor_add_int (x : α) (z : ℤ) : ⌊x + z⌋ = ⌊x⌋ + z :=
eq_of_forall_le_iff $ λ a, by rw [le_floor,
← sub_le_iff_le_add, ← sub_le_iff_le_add, le_floor, int.cast_sub]
theorem floor_sub_int (x : α) (z : ℤ) : ⌊x - z⌋ = ⌊x⌋ - z :=
eq.trans (by rw [int.cast_neg]; refl) (floor_add_int _ _)
lemma abs_sub_lt_one_of_floor_eq_floor {α : Type*} [decidable_linear_ordered_comm_ring α] [floor_ring α]
{x y : α} (h : ⌊x⌋ = ⌊y⌋) : abs (x - y) < 1 :=
begin
have : x < ⌊x⌋ + 1 := lt_floor_add_one x,
have : y < ⌊y⌋ + 1 := lt_floor_add_one y,
have : (⌊x⌋ : α) = ⌊y⌋ := int.cast_inj.2 h,
have : (⌊x⌋: α) ≤ x := floor_le x,
have : (⌊y⌋ : α) ≤ y := floor_le y,
exact abs_sub_lt_iff.2 ⟨by linarith, by linarith⟩
end
lemma floor_eq_iff {r : α} {z : ℤ} :
⌊r⌋ = z ↔ ↑z ≤ r ∧ r < (z + 1) :=
by rw [←le_floor, ←int.cast_one, ←int.cast_add, ←floor_lt,
int.lt_add_one_iff, le_antisymm_iff, and.comm]
/-- The fractional part fract r of r is just r - ⌊r⌋ -/
def fract (r : α) : α := r - ⌊r⌋
-- Mathematical notation is usually {r}. Let's not even go there.
@[simp] lemma floor_add_fract (r : α) : (⌊r⌋ : α) + fract r = r := by unfold fract; simp
@[simp] lemma fract_add_floor (r : α) : fract r + ⌊r⌋ = r := sub_add_cancel _ _
theorem fract_nonneg (r : α) : 0 ≤ fract r :=
sub_nonneg.2 $ floor_le _
theorem fract_lt_one (r : α) : fract r < 1 :=
sub_lt.1 $ sub_one_lt_floor _
@[simp] lemma fract_zero : fract (0 : α) = 0 := by unfold fract; simp
@[simp] lemma fract_coe (z : ℤ) : fract (z : α) = 0 :=
by unfold fract; rw floor_coe; exact sub_self _
@[simp] lemma fract_floor (r : α) : fract (⌊r⌋ : α) = 0 := fract_coe _
@[simp] lemma floor_fract (r : α) : ⌊fract r⌋ = 0 :=
by rw floor_eq_iff; exact ⟨fract_nonneg _,
by rw [int.cast_zero, zero_add]; exact fract_lt_one r⟩
theorem fract_eq_iff {r s : α} : fract r = s ↔ 0 ≤ s ∧ s < 1 ∧ ∃ z : ℤ, r - s = z :=
⟨λ h, by rw ←h; exact ⟨fract_nonneg _, fract_lt_one _,
⟨⌊r⌋, sub_sub_cancel _ _⟩⟩, begin
intro h,
show r - ⌊r⌋ = s, apply eq.symm,
rw [eq_sub_iff_add_eq, add_comm, ←eq_sub_iff_add_eq],
rcases h with ⟨hge, hlt, ⟨z, hz⟩⟩,
rw [hz, int.cast_inj, floor_eq_iff, ←hz],
clear hz, split; linarith {discharger := `[simp]}
end⟩
theorem fract_eq_fract {r s : α} : fract r = fract s ↔ ∃ z : ℤ, r - s = z :=
⟨λ h, ⟨⌊r⌋ - ⌊s⌋, begin
unfold fract at h, rw [int.cast_sub, sub_eq_sub_iff_sub_eq_sub.1 h],
end⟩,
λ h, begin
rcases h with ⟨z, hz⟩,
rw fract_eq_iff,
split, exact fract_nonneg _,
split, exact fract_lt_one _,
use z + ⌊s⌋,
rw [eq_add_of_sub_eq hz, int.cast_add],
unfold fract, simp
end⟩
@[simp] lemma fract_fract (r : α) : fract (fract r) = fract r :=
by rw fract_eq_fract; exact ⟨-⌊r⌋, by unfold fract;simp⟩
theorem fract_add (r s : α) : ∃ z : ℤ, fract (r + s) - fract r - fract s = z :=
⟨⌊r⌋ + ⌊s⌋ - ⌊r + s⌋, by unfold fract; simp⟩
theorem fract_mul_nat (r : α) (b : ℕ) : ∃ z : ℤ, fract r * b - fract (r * b) = z :=
begin
induction b with c hc,
use 0, simp,
rcases hc with ⟨z, hz⟩,
rw [nat.succ_eq_add_one, nat.cast_add, mul_add, mul_add, nat.cast_one, mul_one, mul_one],
rcases fract_add (r * c) r with ⟨y, hy⟩,
use z - y,
rw [int.cast_sub, ←hz, ←hy],
abel
end
/-- `ceil x` is the smallest integer `z` such that `x ≤ z` -/
def ceil (x : α) : ℤ := -⌊-x⌋
notation `⌈` x `⌉` := ceil x
theorem ceil_le {z : ℤ} {x : α} : ⌈x⌉ ≤ z ↔ x ≤ z :=
by rw [ceil, neg_le, le_floor, int.cast_neg, neg_le_neg_iff]
theorem lt_ceil {x : α} {z : ℤ} : z < ⌈x⌉ ↔ (z:α) < x :=
lt_iff_lt_of_le_iff_le ceil_le
theorem le_ceil (x : α) : x ≤ ⌈x⌉ :=
ceil_le.1 (le_refl _)
@[simp] theorem ceil_coe (z : ℤ) : ⌈(z:α)⌉ = z :=
by rw [ceil, ← int.cast_neg, floor_coe, neg_neg]
theorem ceil_mono {a b : α} (h : a ≤ b) : ⌈a⌉ ≤ ⌈b⌉ :=
ceil_le.2 (le_trans h (le_ceil _))
@[simp] theorem ceil_add_int (x : α) (z : ℤ) : ⌈x + z⌉ = ⌈x⌉ + z :=
by rw [ceil, neg_add', floor_sub_int, neg_sub, sub_eq_neg_add]; refl
theorem ceil_sub_int (x : α) (z : ℤ) : ⌈x - z⌉ = ⌈x⌉ - z :=
eq.trans (by rw [int.cast_neg]; refl) (ceil_add_int _ _)
theorem ceil_lt_add_one (x : α) : (⌈x⌉ : α) < x + 1 :=
by rw [← lt_ceil, ← int.cast_one, ceil_add_int]; apply lt_add_one
lemma ceil_pos {a : α} : 0 < ⌈a⌉ ↔ 0 < a :=
⟨ λ h, have ⌊-a⌋ < 0, from neg_of_neg_pos h,
pos_of_neg_neg $ lt_of_not_ge $ (not_iff_not_of_iff floor_nonneg).1 $ not_le_of_gt this,
λ h, have -a < 0, from neg_neg_of_pos h,
neg_pos_of_neg $ lt_of_not_ge $ (not_iff_not_of_iff floor_nonneg).2 $ not_le_of_gt this ⟩
@[simp] theorem ceil_zero : ⌈(0 : α)⌉ = 0 := by simp [ceil]
lemma ceil_nonneg [decidable_rel ((<) : α → α → Prop)] {q : α} (hq : q ≥ 0) : ⌈q⌉ ≥ 0 :=
if h : q > 0 then le_of_lt $ ceil_pos.2 h
else by rw [le_antisymm (le_of_not_lt h) hq, ceil_zero]; trivial
end
class archimedean (α) [ordered_comm_monoid α] : Prop :=
(arch : ∀ (x : α) {y}, 0 < y → ∃ n : ℕ, x ≤ n • y)
theorem exists_nat_gt [linear_ordered_semiring α] [archimedean α]
(x : α) : ∃ n : ℕ, x < n :=
let ⟨n, h⟩ := archimedean.arch x zero_lt_one in
⟨n+1, lt_of_le_of_lt (by rwa ← add_monoid.smul_one)
(nat.cast_lt.2 (nat.lt_succ_self _))⟩
section linear_ordered_ring
variables [linear_ordered_ring α] [archimedean α]
lemma pow_unbounded_of_gt_one (x : α) {y : α}
(hy1 : 1 < y) : ∃ n : ℕ, x < y ^ n :=
have hy0 : 0 < y - 1 := sub_pos_of_lt hy1,
let ⟨n, h⟩ := archimedean.arch x hy0 in
⟨n, calc x ≤ n • (y - 1) : h
... < 1 + n • (y - 1) : by rw add_comm; exact lt_add_one _
... ≤ y ^ n : pow_ge_one_add_sub_mul (le_of_lt hy1) _⟩
lemma exists_nat_pow_near {x : α} {y : α} (hx : 1 < x) (hy : 1 < y) :
∃ n : ℕ, y ^ n ≤ x ∧ x < y ^ (n + 1) :=
have h : ∃ n : ℕ, x < y ^ n, from pow_unbounded_of_gt_one _ hy,
by classical; exact let n := nat.find h in
have hn : x < y ^ n, from nat.find_spec h,
have hnp : 0 < n, from nat.pos_iff_ne_zero.2 (λ hn0,
by rw [hn0, pow_zero] at hn; exact (not_lt_of_gt hn hx)),
have hnsp : nat.pred n + 1 = n, from nat.succ_pred_eq_of_pos hnp,
have hltn : nat.pred n < n, from nat.pred_lt (ne_of_gt hnp),
⟨nat.pred n, le_of_not_lt (nat.find_min h hltn), by rwa hnsp⟩
theorem exists_int_gt (x : α) : ∃ n : ℤ, x < n :=
let ⟨n, h⟩ := exists_nat_gt x in ⟨n, by rwa ← coe_coe⟩
theorem exists_int_lt (x : α) : ∃ n : ℤ, (n : α) < x :=
let ⟨n, h⟩ := exists_int_gt (-x) in ⟨-n, by rw int.cast_neg; exact neg_lt.1 h⟩
theorem exists_floor (x : α) :
∃ (fl : ℤ), ∀ (z : ℤ), z ≤ fl ↔ (z : α) ≤ x :=
begin
haveI := classical.prop_decidable,
have : ∃ (ub : ℤ), (ub:α) ≤ x ∧ ∀ (z : ℤ), (z:α) ≤ x → z ≤ ub :=
int.exists_greatest_of_bdd
(let ⟨n, hn⟩ := exists_int_gt x in ⟨n, λ z h',
int.cast_le.1 $ le_trans h' $ le_of_lt hn⟩)
(let ⟨n, hn⟩ := exists_int_lt x in ⟨n, le_of_lt hn⟩),
refine this.imp (λ fl h z, _),
cases h with h₁ h₂,
exact ⟨λ h, le_trans (int.cast_le.2 h) h₁, h₂ z⟩,
end
end linear_ordered_ring
section linear_ordered_field
lemma exists_int_pow_near [discrete_linear_ordered_field α] [archimedean α]
{x : α} {y : α} (hx : 0 < x) (hy : 1 < y) :
∃ n : ℤ, y ^ n ≤ x ∧ x < y ^ (n + 1) :=
by classical; exact
let ⟨N, hN⟩ := pow_unbounded_of_gt_one x⁻¹ hy in
have he: ∃ m : ℤ, y ^ m ≤ x, from
⟨-N, le_of_lt (by rw [(fpow_neg y (↑N)), one_div_eq_inv];
exact (inv_lt hx (lt_trans (inv_pos hx) hN)).1 hN)⟩,
let ⟨M, hM⟩ := pow_unbounded_of_gt_one x hy in
have hb: ∃ b : ℤ, ∀ m, y ^ m ≤ x → m ≤ b, from
⟨M, λ m hm, le_of_not_lt (λ hlt, not_lt_of_ge
(fpow_le_of_le (le_of_lt hy) (le_of_lt hlt)) (lt_of_le_of_lt hm hM))⟩,
let ⟨n, hn₁, hn₂⟩ := int.exists_greatest_of_bdd hb he in
⟨n, hn₁, lt_of_not_ge (λ hge, not_le_of_gt (int.lt_succ _) (hn₂ _ hge))⟩
variables [linear_ordered_field α] [floor_ring α]
lemma sub_floor_div_mul_nonneg (x : α) {y : α} (hy : 0 < y) :
0 ≤ x - ⌊x / y⌋ * y :=
begin
conv in x {rw ← div_mul_cancel x (ne_of_lt hy).symm},
rw ← sub_mul,
exact mul_nonneg (sub_nonneg.2 (floor_le _)) (le_of_lt hy)
end
lemma sub_floor_div_mul_lt (x : α) {y : α} (hy : 0 < y) :
x - ⌊x / y⌋ * y < y :=
sub_lt_iff_lt_add.2 begin
conv in y {rw ← one_mul y},
conv in x {rw ← div_mul_cancel x (ne_of_lt hy).symm},
rw ← add_mul,
exact (mul_lt_mul_right hy).2 (by rw add_comm; exact lt_floor_add_one _),
end
end linear_ordered_field
instance : archimedean ℕ :=
⟨λ n m m0, ⟨n, by simpa only [mul_one, nat.smul_eq_mul] using nat.mul_le_mul_left n m0⟩⟩
instance : archimedean ℤ :=
⟨λ n m m0, ⟨n.to_nat, le_trans (int.le_to_nat _) $
by simpa only [add_monoid.smul_eq_mul, int.nat_cast_eq_coe_nat, zero_add, mul_one] using mul_le_mul_of_nonneg_left
(int.add_one_le_iff.2 m0) (int.coe_zero_le n.to_nat)⟩⟩
noncomputable def archimedean.floor_ring (α)
[linear_ordered_ring α] [archimedean α] : floor_ring α :=
{ floor := λ x, classical.some (exists_floor x),
le_floor := λ z x, classical.some_spec (exists_floor x) z }
section linear_ordered_field
variables [linear_ordered_field α]
theorem archimedean_iff_nat_lt :
archimedean α ↔ ∀ x : α, ∃ n : ℕ, x < n :=
⟨@exists_nat_gt α _, λ H, ⟨λ x y y0,
(H (x / y)).imp $ λ n h, le_of_lt $
by rwa [div_lt_iff y0, ← add_monoid.smul_eq_mul] at h⟩⟩
theorem archimedean_iff_nat_le :
archimedean α ↔ ∀ x : α, ∃ n : ℕ, x ≤ n :=
archimedean_iff_nat_lt.trans
⟨λ H x, (H x).imp $ λ _, le_of_lt,
λ H x, let ⟨n, h⟩ := H x in ⟨n+1,
lt_of_le_of_lt h (nat.cast_lt.2 (lt_add_one _))⟩⟩
theorem exists_rat_gt [archimedean α] (x : α) : ∃ q : ℚ, x < q :=
let ⟨n, h⟩ := exists_nat_gt x in ⟨n, by rwa rat.cast_coe_nat⟩
theorem archimedean_iff_rat_lt :
archimedean α ↔ ∀ x : α, ∃ q : ℚ, x < q :=
⟨@exists_rat_gt α _,
λ H, archimedean_iff_nat_lt.2 $ λ x,
let ⟨q, h⟩ := H x in
⟨rat.nat_ceil q, lt_of_lt_of_le h $
by simpa only [rat.cast_coe_nat] using (@rat.cast_le α _ _ _).2 (rat.le_nat_ceil _)⟩⟩
theorem archimedean_iff_rat_le :
archimedean α ↔ ∀ x : α, ∃ q : ℚ, x ≤ q :=
archimedean_iff_rat_lt.trans
⟨λ H x, (H x).imp $ λ _, le_of_lt,
λ H x, let ⟨n, h⟩ := H x in ⟨n+1,
lt_of_le_of_lt h (rat.cast_lt.2 (lt_add_one _))⟩⟩
variable [archimedean α]
theorem exists_rat_lt (x : α) : ∃ q : ℚ, (q : α) < x :=
let ⟨n, h⟩ := exists_int_lt x in ⟨n, by rwa rat.cast_coe_int⟩
theorem exists_rat_btwn {x y : α} (h : x < y) : ∃ q : ℚ, x < q ∧ (q:α) < y :=
begin
cases exists_nat_gt (y - x)⁻¹ with n nh,
cases exists_floor (x * n) with z zh,
refine ⟨(z + 1 : ℤ) / n, _⟩,
have n0 := nat.cast_pos.1 (lt_trans (inv_pos (sub_pos.2 h)) nh),
have n0' := (@nat.cast_pos α _ _).2 n0,
rw [rat.cast_div_of_ne_zero, rat.cast_coe_nat, rat.cast_coe_int, div_lt_iff n0'],
refine ⟨(lt_div_iff n0').2 $
(lt_iff_lt_of_le_iff_le (zh _)).1 (lt_add_one _), _⟩,
rw [int.cast_add, int.cast_one],
refine lt_of_le_of_lt (add_le_add_right ((zh _).1 (le_refl _)) _) _,
rwa [← lt_sub_iff_add_lt', ← sub_mul,
← div_lt_iff' (sub_pos.2 h), one_div_eq_inv],
{ rw [rat.coe_int_denom, nat.cast_one], exact one_ne_zero },
{ intro H, rw [rat.coe_nat_num, ← coe_coe, nat.cast_eq_zero] at H, subst H, cases n0 },
{ rw [rat.coe_nat_denom, nat.cast_one], exact one_ne_zero }
end
theorem exists_nat_one_div_lt {ε : α} (hε : ε > 0) : ∃ n : ℕ, 1 / (n + 1: α) < ε :=
begin
cases archimedean_iff_nat_lt.1 (by apply_instance) (1/ε) with n hn,
existsi n,
apply div_lt_of_mul_lt_of_pos,
{ simp, apply add_pos_of_pos_of_nonneg zero_lt_one, apply nat.cast_nonneg },
{ apply (div_lt_iff' hε).1,
transitivity,
{ exact hn },
{ simp [zero_lt_one] }}
end
theorem exists_pos_rat_lt {x : α} (x0 : 0 < x) : ∃ q : ℚ, 0 < q ∧ (q : α) < x :=
by simpa only [rat.cast_pos] using exists_rat_btwn x0
include α
@[simp] theorem rat.cast_floor (x : ℚ) :
by haveI := archimedean.floor_ring α; exact ⌊(x:α)⌋ = ⌊x⌋ :=
begin
haveI := archimedean.floor_ring α,
apply le_antisymm,
{ rw [le_floor, ← @rat.cast_le α, rat.cast_coe_int],
apply floor_le },
{ rw [le_floor, ← rat.cast_coe_int, rat.cast_le],
apply floor_le }
end
/-- `round` rounds a number to the nearest integer. `round (1 / 2) = 1` -/
def round [floor_ring α] (x : α) : ℤ := ⌊x + 1 / 2⌋
end linear_ordered_field
section
variables [discrete_linear_ordered_field α] [archimedean α]
theorem exists_rat_near (x : α) {ε : α} (ε0 : ε > 0) :
∃ q : ℚ, abs (x - q) < ε :=
let ⟨q, h₁, h₂⟩ := exists_rat_btwn $
lt_trans ((sub_lt_self_iff x).2 ε0) ((lt_add_iff_pos_left x).2 ε0) in
⟨q, abs_sub_lt_iff.2 ⟨sub_lt.1 h₁, sub_lt_iff_lt_add.2 h₂⟩⟩
lemma abs_sub_round [floor_ring α] (x : α) : abs (x - round x) ≤ 1 / 2 :=
begin
rw [round, abs_sub_le_iff],
have := floor_le (x + 1 / 2),
have := lt_floor_add_one (x + 1 / 2),
split; linarith
end
instance : archimedean ℚ :=
archimedean_iff_rat_le.2 $ λ q, ⟨q, by rw rat.cast_id⟩
@[simp] theorem rat.cast_round {α : Type*} [discrete_linear_ordered_field α]
[archimedean α] (x : ℚ) : by haveI := archimedean.floor_ring α;
exact round (x:α) = round x :=
have ((x + (1 : ℚ) / (2 : ℚ) : ℚ) : α) = x + 1 / 2, by simp,
by rw [round, round, ← this, rat.cast_floor]
end
|
22f19ac5d7f9748f1241533bbaf8cd2b5a383831 | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/order/interval.lean | bdaa1250c6a6ddabd4fa69577bb1d66607b51f19 | [
"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 | 18,557 | lean | /-
Copyright (c) 2022 Yaël Dillies. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies
-/
import data.set.intervals.basic
import data.set.lattice
import data.set_like.basic
/-!
# Order intervals
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
This file defines (nonempty) closed intervals in an order (see `set.Icc`). This is a prototype for
interval arithmetic.
## Main declarations
* `nonempty_interval`: Nonempty intervals. Pairs where the second element is greater than the first.
* `interval`: Intervals. Either `∅` or a nonempty interval.
-/
open function order_dual set
variables {α β γ δ : Type*} {ι : Sort*} {κ : ι → Sort*}
/-- The nonempty closed intervals in an order.
We define intervals by the pair of endpoints `fst`, `snd`. To convert intervals to the set of
elements between these endpoints, use the coercion `nonempty_interval α → set α`. -/
@[ext] structure nonempty_interval (α : Type*) [has_le α] extends α × α :=
(fst_le_snd : fst ≤ snd)
namespace nonempty_interval
section has_le
variables [has_le α] {s t : nonempty_interval α}
lemma to_prod_injective : injective (to_prod : nonempty_interval α → α × α) :=
λ s t, (ext_iff _ _).2
/-- The injection that induces the order on intervals. -/
def to_dual_prod : nonempty_interval α → αᵒᵈ × α := to_prod
@[simp] lemma to_dual_prod_apply (s : nonempty_interval α) :
s.to_dual_prod = (to_dual s.fst, s.snd) := prod.mk.eta.symm
lemma to_dual_prod_injective : injective (to_dual_prod : nonempty_interval α → αᵒᵈ × α) :=
to_prod_injective
instance [is_empty α] : is_empty (nonempty_interval α) := ⟨λ s, is_empty_elim s.fst⟩
instance [subsingleton α] : subsingleton (nonempty_interval α) :=
to_dual_prod_injective.subsingleton
instance : has_le (nonempty_interval α) := ⟨λ s t, t.fst ≤ s.fst ∧ s.snd ≤ t.snd⟩
lemma le_def : s ≤ t ↔ t.fst ≤ s.fst ∧ s.snd ≤ t.snd := iff.rfl
/-- `to_dual_prod` as an order embedding. -/
@[simps] def to_dual_prod_hom : nonempty_interval α ↪o αᵒᵈ × α :=
{ to_fun := to_dual_prod,
inj' := to_dual_prod_injective,
map_rel_iff' := λ _ _, iff.rfl }
/-- Turn an interval into an interval in the dual order. -/
def dual : nonempty_interval α ≃ nonempty_interval αᵒᵈ :=
{ to_fun := λ s, ⟨s.to_prod.swap, s.fst_le_snd⟩,
inv_fun := λ s, ⟨s.to_prod.swap, s.fst_le_snd⟩,
left_inv := λ s, ext _ _ $ prod.swap_swap _,
right_inv := λ s, ext _ _ $ prod.swap_swap _ }
@[simp] lemma fst_dual (s : nonempty_interval α) : s.dual.fst = to_dual s.snd := rfl
@[simp] lemma snd_dual (s : nonempty_interval α) : s.dual.snd = to_dual s.fst := rfl
end has_le
section preorder
variables [preorder α] [preorder β] [preorder γ] [preorder δ] {s : nonempty_interval α} {x : α × α}
{a : α}
instance : preorder (nonempty_interval α) := preorder.lift to_dual_prod
instance : has_coe_t (nonempty_interval α) (set α) := ⟨λ s, Icc s.fst s.snd⟩
@[priority 100] instance : has_mem α (nonempty_interval α) := ⟨λ a s, a ∈ (s : set α)⟩
@[simp] lemma mem_mk {hx : x.1 ≤ x.2} : a ∈ mk x hx ↔ x.1 ≤ a ∧ a ≤ x.2 := iff.rfl
lemma mem_def : a ∈ s ↔ s.fst ≤ a ∧ a ≤ s.snd := iff.rfl
@[simp] lemma coe_nonempty (s : nonempty_interval α) : (s : set α).nonempty :=
nonempty_Icc.2 s.fst_le_snd
/-- `{a}` as an interval. -/
@[simps] def pure (a : α) : nonempty_interval α := ⟨⟨a, a⟩, le_rfl⟩
lemma mem_pure_self (a : α) : a ∈ pure a := ⟨le_rfl, le_rfl⟩
lemma pure_injective : injective (pure : α → nonempty_interval α) :=
λ s t, congr_arg $ prod.fst ∘ to_prod
@[simp] lemma dual_pure (a : α) : (pure a).dual = pure (to_dual a) := rfl
instance [inhabited α] : inhabited (nonempty_interval α) := ⟨pure default⟩
instance : ∀ [nonempty α], nonempty (nonempty_interval α) := nonempty.map pure
instance [nontrivial α] : nontrivial (nonempty_interval α) := pure_injective.nontrivial
/-- Pushforward of nonempty intervals. -/
@[simps] def map (f : α →o β) (a : nonempty_interval α) : nonempty_interval β :=
⟨a.to_prod.map f f, f.mono a.fst_le_snd⟩
@[simp] lemma map_pure (f : α →o β) (a : α) : (pure a).map f = pure (f a) := rfl
@[simp] lemma map_map (g : β →o γ) (f : α →o β) (a : nonempty_interval α) :
(a.map f).map g = a.map (g.comp f) := rfl
@[simp] lemma dual_map (f : α →o β) (a : nonempty_interval α) :
(a.map f).dual = a.dual.map f.dual := rfl
/-- Binary pushforward of nonempty intervals. -/
@[simps]
def map₂ (f : α → β → γ) (h₀ : ∀ b, monotone (λ a, f a b)) (h₁ : ∀ a, monotone (f a)) :
nonempty_interval α → nonempty_interval β → nonempty_interval γ :=
λ s t, ⟨(f s.fst t.fst, f s.snd t.snd), (h₀ _ s.fst_le_snd).trans $ h₁ _ t.fst_le_snd⟩
@[simp] lemma map₂_pure (f : α → β → γ) (h₀ h₁) (a : α) (b : β) :
map₂ f h₀ h₁ (pure a) (pure b) = pure (f a b) := rfl
@[simp] lemma dual_map₂ (f : α → β → γ) (h₀ h₁ s t) :
(map₂ f h₀ h₁ s t).dual = map₂ (λ a b, to_dual $ f (of_dual a) $ of_dual b)
(λ _, (h₀ _).dual) (λ _, (h₁ _).dual) s.dual t.dual := rfl
variables [bounded_order α]
instance : order_top (nonempty_interval α) :=
{ top := ⟨⟨⊥, ⊤⟩, bot_le⟩,
le_top := λ a, ⟨bot_le, le_top⟩ }
@[simp] lemma dual_top : (⊤ : nonempty_interval α).dual = ⊤ := rfl
end preorder
section partial_order
variables [partial_order α] [partial_order β] {s t : nonempty_interval α} {x : α × α} {a b : α}
instance : partial_order (nonempty_interval α) := partial_order.lift _ to_dual_prod_injective
/-- Consider a nonempty interval `[a, b]` as the set `[a, b]`. -/
def coe_hom : nonempty_interval α ↪o set α :=
order_embedding.of_map_le_iff (λ s, Icc s.fst s.snd) (λ s t, Icc_subset_Icc_iff s.fst_le_snd)
instance : set_like (nonempty_interval α) α :=
{ coe := λ s, Icc s.fst s.snd,
coe_injective' := coe_hom.injective }
@[simp, norm_cast] lemma coe_subset_coe : (s : set α) ⊆ t ↔ s ≤ t := (@coe_hom α _).le_iff_le
@[simp, norm_cast] lemma coe_ssubset_coe : (s : set α) ⊂ t ↔ s < t := (@coe_hom α _).lt_iff_lt
@[simp] lemma coe_coe_hom : (coe_hom : nonempty_interval α → set α) = coe := rfl
@[simp, norm_cast] lemma coe_pure (a : α) : (pure a : set α) = {a} := Icc_self _
@[simp] lemma mem_pure : b ∈ pure a ↔ b = a :=
by rw [←set_like.mem_coe, coe_pure, mem_singleton_iff]
@[simp, norm_cast]
lemma coe_top [bounded_order α] : ((⊤ : nonempty_interval α) : set α) = univ := Icc_bot_top
@[simp, norm_cast]
lemma coe_dual (s : nonempty_interval α) : (s.dual : set αᵒᵈ) = of_dual ⁻¹' s := dual_Icc
lemma subset_coe_map (f : α →o β) (s : nonempty_interval α) : f '' s ⊆ s.map f :=
image_subset_iff.2 $ λ a ha, ⟨f.mono ha.1, f.mono ha.2⟩
end partial_order
section lattice
variables [lattice α]
instance : has_sup (nonempty_interval α) :=
⟨λ s t, ⟨⟨s.fst ⊓ t.fst, s.snd ⊔ t.snd⟩, inf_le_left.trans $ s.fst_le_snd.trans le_sup_left⟩⟩
instance : semilattice_sup (nonempty_interval α) :=
to_dual_prod_injective.semilattice_sup _ $ λ _ _, rfl
@[simp] lemma fst_sup (s t : nonempty_interval α) : (s ⊔ t).fst = s.fst ⊓ t.fst := rfl
@[simp] lemma snd_sup (s t : nonempty_interval α) : (s ⊔ t).snd = s.snd ⊔ t.snd := rfl
end lattice
end nonempty_interval
/-- The closed intervals in an order.
We represent intervals either as `⊥` or a nonempty interval given by its endpoints `fst`, `snd`.
To convert intervals to the set of elements between these endpoints, use the coercion
`interval α → set α`. -/
@[derive [inhabited, has_le, order_bot]]
def interval (α : Type*) [has_le α] := with_bot (nonempty_interval α)
namespace interval
section has_le
variables [has_le α] {s t : interval α}
instance : has_coe_t (nonempty_interval α) (interval α) := with_bot.has_coe_t
instance can_lift : can_lift (interval α) (nonempty_interval α) coe (λ r, r ≠ ⊥) :=
with_bot.can_lift
lemma coe_injective : injective (coe : nonempty_interval α → interval α) := with_bot.coe_injective
@[simp, norm_cast] lemma coe_inj {s t : nonempty_interval α} : (s : interval α) = t ↔ s = t :=
with_bot.coe_inj
@[protected] lemma «forall» {p : interval α → Prop} :
(∀ s, p s) ↔ p ⊥ ∧ ∀ s : nonempty_interval α, p s := option.forall
@[protected] lemma «exists» {p : interval α → Prop} :
(∃ s, p s) ↔ p ⊥ ∨ ∃ s : nonempty_interval α, p s := option.exists
instance [is_empty α] : unique (interval α) := option.unique
/-- Turn an interval into an interval in the dual order. -/
def dual : interval α ≃ interval αᵒᵈ := nonempty_interval.dual.option_congr
end has_le
section preorder
variables [preorder α] [preorder β] [preorder γ]
instance : preorder (interval α) := with_bot.preorder
/-- `{a}` as an interval. -/
def pure (a : α) : interval α := nonempty_interval.pure a
lemma pure_injective : injective (pure : α → interval α) :=
coe_injective.comp nonempty_interval.pure_injective
@[simp] lemma dual_pure (a : α) : (pure a).dual = pure (to_dual a) := rfl
@[simp] lemma dual_bot : (⊥ : interval α).dual = ⊥ := rfl
@[simp] lemma pure_ne_bot {a : α} : pure a ≠ ⊥ := with_bot.coe_ne_bot
@[simp] lemma bot_ne_pure {a : α} : ⊥ ≠ pure a := with_bot.bot_ne_coe
instance [nonempty α] : nontrivial (interval α) := option.nontrivial
/-- Pushforward of intervals. -/
def map (f : α →o β) : interval α → interval β := with_bot.map (nonempty_interval.map f)
@[simp] lemma map_pure (f : α →o β) (a : α) : (pure a).map f = pure (f a) := rfl
@[simp] lemma map_map (g : β →o γ) (f : α →o β) (s : interval α) :
(s.map f).map g = s.map (g.comp f) := option.map_map _ _ _
@[simp] lemma dual_map (f : α →o β) (s : interval α) : (s.map f).dual = s.dual.map f.dual :=
by { cases s, { refl }, { exact with_bot.map_comm rfl _ } }
variables [bounded_order α]
instance : bounded_order (interval α) := with_bot.bounded_order
@[simp] lemma dual_top : (⊤ : interval α).dual = ⊤ := rfl
end preorder
section partial_order
variables [partial_order α] [partial_order β] {s t : interval α} {a b : α}
instance : partial_order (interval α) := with_bot.partial_order
/-- Consider a interval `[a, b]` as the set `[a, b]`. -/
def coe_hom : interval α ↪o set α :=
order_embedding.of_map_le_iff (λ s, match s with
| ⊥ := ∅
| some s := s
end) (λ s t, match s, t with
| ⊥, t := iff_of_true bot_le bot_le
| some s, ⊥ := iff_of_false (λ h, s.coe_nonempty.ne_empty $ le_bot_iff.1 h)
(with_bot.not_coe_le_bot _)
| some s, some t := (@nonempty_interval.coe_hom α _).le_iff_le.trans with_bot.some_le_some.symm
end)
instance : set_like (interval α) α :=
{ coe := coe_hom,
coe_injective' := coe_hom.injective }
@[simp, norm_cast] lemma coe_subset_coe : (s : set α) ⊆ t ↔ s ≤ t := (@coe_hom α _).le_iff_le
@[simp, norm_cast] lemma coe_ssubset_coe : (s : set α) ⊂ t ↔ s < t := (@coe_hom α _).lt_iff_lt
@[simp, norm_cast] lemma coe_pure (a : α) : (pure a : set α) = {a} := Icc_self _
@[simp, norm_cast] lemma coe_coe (s : nonempty_interval α) : ((s : interval α) : set α) = s := rfl
@[simp, norm_cast] lemma coe_bot : ((⊥ : interval α) : set α) = ∅ := rfl
@[simp, norm_cast] lemma coe_top [bounded_order α] : ((⊤ : interval α) : set α) = univ :=
Icc_bot_top
@[simp, norm_cast] lemma coe_dual (s : interval α) : (s.dual : set αᵒᵈ) = of_dual ⁻¹' s :=
by { cases s, { refl }, exact s.coe_dual }
lemma subset_coe_map (f : α →o β) : ∀ s : interval α, f '' s ⊆ s.map f
| ⊥ := by simp
| (s : nonempty_interval α) := s.subset_coe_map _
@[simp] lemma mem_pure : b ∈ pure a ↔ b = a :=
by rw [←set_like.mem_coe, coe_pure, mem_singleton_iff]
lemma mem_pure_self (a : α) : a ∈ pure a := mem_pure.2 rfl
end partial_order
section lattice
variables [lattice α]
instance : semilattice_sup (interval α) := with_bot.semilattice_sup
section decidable
variables [@decidable_rel α (≤)]
instance : lattice (interval α) :=
{ inf := λ s t, match s, t with
| ⊥, t := ⊥
| s, ⊥ := ⊥
| some s, some t := if h : s.fst ≤ t.snd ∧ t.fst ≤ s.snd then some
⟨⟨s.fst ⊔ t.fst, s.snd ⊓ t.snd⟩, sup_le (le_inf s.fst_le_snd h.1) $ le_inf h.2 t.fst_le_snd⟩
else ⊥
end,
inf_le_left := λ s t, match s, t with
| ⊥, ⊥ := bot_le
| ⊥, some t := bot_le
| some s, ⊥ := bot_le
| some s, some t := begin
change dite _ _ _ ≤ _,
split_ifs,
{ exact with_bot.some_le_some.2 ⟨le_sup_left, inf_le_left⟩ },
{ exact bot_le }
end
end,
inf_le_right := λ s t, match s, t with
| ⊥, ⊥ := bot_le
| ⊥, some t := bot_le
| some s, ⊥ := bot_le
| some s, some t := begin
change dite _ _ _ ≤ _,
split_ifs,
{ exact with_bot.some_le_some.2 ⟨le_sup_right, inf_le_right⟩ },
{ exact bot_le }
end
end,
le_inf := λ s t c, match s, t, c with
| ⊥, t, c := λ _ _, bot_le
| some s, t, c := λ hb hc, begin
lift t to nonempty_interval α using ne_bot_of_le_ne_bot with_bot.coe_ne_bot hb,
lift c to nonempty_interval α using ne_bot_of_le_ne_bot with_bot.coe_ne_bot hc,
change _ ≤ dite _ _ _,
simp only [with_bot.some_eq_coe, with_bot.coe_le_coe] at ⊢ hb hc,
rw [dif_pos, with_bot.coe_le_coe],
exact ⟨sup_le hb.1 hc.1, le_inf hb.2 hc.2⟩,
exact ⟨hb.1.trans $ s.fst_le_snd.trans hc.2, hc.1.trans $ s.fst_le_snd.trans hb.2⟩,
end
end,
..interval.semilattice_sup }
@[simp, norm_cast] lemma coe_inf (s t : interval α) : (↑(s ⊓ t) : set α) = s ∩ t :=
begin
cases s,
{ rw [with_bot.none_eq_bot, bot_inf_eq],
exact (empty_inter _).symm },
cases t,
{ rw [with_bot.none_eq_bot, inf_bot_eq],
exact (inter_empty _).symm },
refine (_ : coe (dite _ _ _) = _).trans Icc_inter_Icc.symm,
split_ifs,
{ refl },
{ exact (Icc_eq_empty $ λ H,
h ⟨le_sup_left.trans $ H.trans inf_le_right, le_sup_right.trans $ H.trans inf_le_left⟩).symm }
end
end decidable
@[simp, norm_cast]
lemma disjoint_coe (s t : interval α) : disjoint (s : set α) t ↔ disjoint s t :=
begin
classical,
rw [disjoint_iff_inf_le, disjoint_iff_inf_le, le_eq_subset, ←coe_subset_coe, coe_inf], refl
end
end lattice
end interval
namespace nonempty_interval
section preorder
variables [preorder α] {s : nonempty_interval α} {a : α}
@[simp, norm_cast] lemma coe_pure_interval (a : α) : (pure a : interval α) = interval.pure a := rfl
@[simp, norm_cast] lemma coe_eq_pure : (s : interval α) = interval.pure a ↔ s = pure a :=
by rw [←interval.coe_inj, coe_pure_interval]
@[simp, norm_cast]
lemma coe_top_interval [bounded_order α] : ((⊤ : nonempty_interval α) : interval α) = ⊤ := rfl
end preorder
@[simp, norm_cast]
lemma mem_coe_interval [partial_order α] {s : nonempty_interval α} {x : α} :
x ∈ (s : interval α) ↔ x ∈ s := iff.rfl
@[simp, norm_cast] lemma coe_sup_interval [lattice α] (s t : nonempty_interval α) :
(↑(s ⊔ t) : interval α) = s ⊔ t := rfl
end nonempty_interval
namespace interval
section complete_lattice
variables [complete_lattice α]
noncomputable instance [@decidable_rel α (≤)] : complete_lattice (interval α) :=
by classical; exact { Sup := λ S, if h : S ⊆ {⊥} then ⊥ else some
⟨⟨⨅ (s : nonempty_interval α) (h : ↑s ∈ S), s.fst,
⨆ (s : nonempty_interval α) (h : ↑s ∈ S), s.snd⟩, begin
obtain ⟨s, hs, ha⟩ := not_subset.1 h,
lift s to nonempty_interval α using ha,
exact infi₂_le_of_le s hs (le_supr₂_of_le s hs s.fst_le_snd)
end⟩,
le_Sup := λ s s ha, begin
split_ifs,
{ exact (h ha).le },
cases s,
{ exact bot_le },
{ exact with_bot.some_le_some.2 ⟨infi₂_le _ ha, le_supr₂_of_le _ ha le_rfl⟩ }
end,
Sup_le := λ s s ha, begin
split_ifs,
{ exact bot_le },
obtain ⟨b, hs, hb⟩ := not_subset.1 h,
lift s to nonempty_interval α using ne_bot_of_le_ne_bot hb (ha _ hs),
exact with_bot.coe_le_coe.2 ⟨le_infi₂ $ λ c hc, (with_bot.coe_le_coe.1 $ ha _ hc).1,
supr₂_le $ λ c hc, (with_bot.coe_le_coe.1 $ ha _ hc).2⟩,
end,
Inf := λ S, if h : ⊥ ∉ S ∧ ∀ ⦃s : nonempty_interval α⦄, ↑s ∈ S → ∀ ⦃t : nonempty_interval α⦄,
↑t ∈ S → s.fst ≤ t.snd then some
⟨⟨⨆ (s : nonempty_interval α) (h : ↑s ∈ S), s.fst,
⨅ (s : nonempty_interval α) (h : ↑s ∈ S), s.snd⟩,
supr₂_le $ λ s hs, le_infi₂ $ h.2 hs⟩ else ⊥,
Inf_le := λ s s ha, begin
split_ifs,
{ lift s to nonempty_interval α using ne_of_mem_of_not_mem ha h.1,
exact with_bot.coe_le_coe.2 ⟨le_supr₂ s ha, infi₂_le s ha⟩ },
{ exact bot_le }
end,
le_Inf := λ S s ha, begin
cases s,
{ exact bot_le },
split_ifs,
{ exact with_bot.some_le_some.2 ⟨supr₂_le $ λ t hb, (with_bot.coe_le_coe.1 $ ha _ hb).1,
le_infi₂ $ λ t hb, (with_bot.coe_le_coe.1 $ ha _ hb).2⟩ },
rw [not_and_distrib, not_not] at h,
cases h,
{ exact ha _ h },
cases h (λ t hb c hc, (with_bot.coe_le_coe.1 $ ha _ hb).1.trans $ s.fst_le_snd.trans
(with_bot.coe_le_coe.1 $ ha _ hc).2),
end,
..interval.lattice, ..interval.bounded_order }
@[simp, norm_cast] lemma coe_Inf [@decidable_rel α (≤)] (S : set (interval α)) :
↑(Inf S) = ⋂ s ∈ S, (s : set α) :=
begin
change coe (dite _ _ _) = _,
split_ifs,
{ ext,
simp [with_bot.some_eq_coe, interval.forall, h.1, ←forall_and_distrib,
←nonempty_interval.mem_def] },
simp_rw [not_and_distrib, not_not] at h,
cases h,
{ refine (eq_empty_of_subset_empty _).symm,
exact Inter₂_subset_of_subset _ h subset.rfl },
{ refine (not_nonempty_iff_eq_empty.1 _).symm,
rintro ⟨x, hx⟩,
rw mem_Inter₂ at hx,
exact h (λ s ha t hb, (hx _ ha).1.trans (hx _ hb).2) }
end
@[simp, norm_cast] lemma coe_infi [@decidable_rel α (≤)] (f : ι → interval α) :
↑(⨅ i, f i) = ⋂ i, (f i : set α) :=
by simp [infi]
@[simp, norm_cast] lemma coe_infi₂ [@decidable_rel α (≤)] (f : Π i, κ i → interval α) :
↑(⨅ i j, f i j) = ⋂ i j, (f i j : set α) :=
by simp_rw [coe_infi]
end complete_lattice
end interval
|
7e602896f174df715e550319b3876a8aa4926bbd | 8d65764a9e5f0923a67fc435eb1a5a1d02fd80e3 | /src/algebra/ordered_sub.lean | 051c4bd7c1b48b046bbf05c20dda590fa429aa72 | [
"Apache-2.0"
] | permissive | troyjlee/mathlib | e18d4b8026e32062ab9e89bc3b003a5d1cfec3f5 | 45e7eb8447555247246e3fe91c87066506c14875 | refs/heads/master | 1,689,248,035,046 | 1,629,470,528,000 | 1,629,470,528,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 25,609 | lean | /-
Copyright (c) 2021 Floris van Doorn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Floris van Doorn
-/
import algebra.ordered_monoid
/-!
# Ordered Subtraction
This file proves lemmas relating (truncated) subtraction with an order. We provide a class
`has_ordered_sub` stating that `a - b ≤ c ↔ a ≤ c + b`.
The subtraction discussed here could both be normal subtraction in an additive group or truncated
subtraction on a canonically ordered monoid (`ℕ`, `multiset`, `enat`, `ennreal`, ...)
## Implementation details
`has_ordered_sub` is a mixin type-class, so that we can use the results in this file even in cases
where we don't have a `canonically_ordered_add_monoid` instance
(even though that is our main focus). Conversely, this means we can use
`canonically_ordered_add_monoid` without necessarily having to define a subtraction.
The results in this file are ordered by the type-class assumption needed to prove it.
This means that similar results might not be close to each other. Furthermore, we don't prove
implications if a bi-implication can be proven under the same assumptions.
Many results about this subtraction are primed, to not conflict with similar lemmas about ordered
groups.
We provide a second version of most results that require `[contravariant_class α α (+) (≤)]`. In the
second version we replace this type-class assumption by explicit `add_le_cancellable` assumptions.
TODO: maybe we should make a multiplicative version of this, so that we can replace some identical
lemmas about subtraction/division in `ordered_[add_]comm_group` with these.
-/
variables {α : Type*}
/-- `has_ordered_sub α` means that `α` has a subtraction characterized by `a - b ≤ c ↔ a ≤ c + b`.
In other words, `a - b` is the least `c` such that `a ≤ b + c`.
This is satisfied both by the subtraction in additive ordered groups and by truncated subtraction
in canonically ordered monoids on many specific types.
-/
class has_ordered_sub (α : Type*) [preorder α] [has_add α] [has_sub α] :=
(sub_le_iff_right : ∀ a b c : α, a - b ≤ c ↔ a ≤ c + b)
section ordered_add_comm_monoid
variables {a b c d : α} [partial_order α] [add_comm_monoid α] [has_sub α] [has_ordered_sub α]
@[simp] lemma sub_le_iff_right : a - b ≤ c ↔ a ≤ c + b :=
has_ordered_sub.sub_le_iff_right a b c
lemma sub_le_iff_left : a - b ≤ c ↔ a ≤ b + c :=
by rw [sub_le_iff_right, add_comm]
lemma le_add_sub : a ≤ b + (a - b) :=
sub_le_iff_left.mp le_rfl
/-- See `add_sub_cancel_left` for the equality if `contravariant_class α α (+) (≤)`. -/
lemma add_sub_le_left : a + b - a ≤ b :=
sub_le_iff_left.mpr le_rfl
/-- See `add_sub_cancel_right` for the equality if `contravariant_class α α (+) (≤)`. -/
lemma add_sub_le_right : a + b - b ≤ a :=
sub_le_iff_right.mpr le_rfl
lemma le_sub_add : b ≤ (b - a) + a :=
sub_le_iff_right.mp le_rfl
lemma sub_le_sub_right' (h : a ≤ b) (c : α) : a - c ≤ b - c :=
sub_le_iff_left.mpr $ h.trans le_add_sub
lemma sub_le_iff_sub_le : a - b ≤ c ↔ a - c ≤ b :=
by rw [sub_le_iff_left, sub_le_iff_right]
lemma sub_sub' (b a c : α) : b - a - c = b - (a + c) :=
begin
apply le_antisymm,
{ rw [sub_le_iff_left, sub_le_iff_left, ← add_assoc, ← sub_le_iff_left] },
{ rw [sub_le_iff_left, add_assoc, ← sub_le_iff_left, ← sub_le_iff_left] }
end
/-- See `sub_sub_cancel_of_le` for the equality. -/
lemma sub_sub_le : b - (b - a) ≤ a :=
sub_le_iff_right.mpr le_add_sub
section cov
variable [covariant_class α α (+) (≤)]
lemma sub_le_sub_left' (h : a ≤ b) (c : α) : c - b ≤ c - a :=
sub_le_iff_left.mpr $ le_add_sub.trans $ add_le_add_right h _
lemma sub_le_sub' (hab : a ≤ b) (hcd : c ≤ d) : a - d ≤ b - c :=
(sub_le_sub_right' hab _).trans $ sub_le_sub_left' hcd _
lemma sub_add_eq_sub_sub' : a - (b + c) = a - b - c :=
begin
refine le_antisymm (sub_le_iff_left.mpr _)
(sub_le_iff_left.mpr $ sub_le_iff_left.mpr _),
{ rw [add_assoc], refine le_trans le_add_sub (add_le_add_left le_add_sub _) },
{ rw [← add_assoc], apply le_add_sub }
end
lemma sub_add_eq_sub_sub_swap' : a - (b + c) = a - c - b :=
by { rw [add_comm], exact sub_add_eq_sub_sub' }
lemma add_le_add_add_sub : a + b ≤ (a + c) + (b - c) :=
by { rw [add_assoc], exact add_le_add_left le_add_sub a }
lemma sub_right_comm' : a - b - c = a - c - b :=
by simp_rw [← sub_add_eq_sub_sub', add_comm]
/-- See `add_sub_assoc_of_le` for the equality. -/
lemma add_sub_le_assoc : a + b - c ≤ a + (b - c) :=
by { rw [sub_le_iff_left, add_left_comm], exact add_le_add_left le_add_sub a }
lemma le_sub_add_add : a + b ≤ (a - c) + (b + c) :=
by { rw [add_comm a, add_comm (a - c)], exact add_le_add_add_sub }
lemma sub_le_sub_add_sub : a - c ≤ (a - b) + (b - c) :=
begin
rw [sub_le_iff_left, ← add_assoc, add_right_comm],
refine le_add_sub.trans (add_le_add_right le_add_sub _),
end
lemma sub_sub_sub_le_sub : (c - a) - (c - b) ≤ b - a :=
begin
rw [sub_le_iff_left, sub_le_iff_left, add_left_comm],
refine le_sub_add.trans (add_le_add_left le_add_sub _),
end
end cov
/-! Lemmas that assume that an element is `add_le_cancellable`. -/
namespace add_le_cancellable
protected lemma le_add_sub_swap (hb : add_le_cancellable b) : a ≤ b + a - b :=
hb le_add_sub
protected lemma le_add_sub (hb : add_le_cancellable b) : a ≤ a + b - b :=
by { rw [add_comm], exact hb.le_add_sub_swap }
protected lemma sub_eq_of_eq_add (hb : add_le_cancellable b) (h : a = c + b) : a - b = c :=
le_antisymm (sub_le_iff_right.mpr h.le) $
by { rw h, exact hb.le_add_sub }
protected lemma eq_sub_of_add_eq (hc : add_le_cancellable c) (h : a + c = b) : a = b - c :=
(hc.sub_eq_of_eq_add h.symm).symm
@[simp]
protected lemma add_sub_cancel_right (hb : add_le_cancellable b) : a + b - b = a :=
hb.sub_eq_of_eq_add $ by rw [add_comm]
@[simp]
protected lemma add_sub_cancel_left (ha : add_le_cancellable a) : a + b - a = b :=
ha.sub_eq_of_eq_add $ add_comm a b
protected lemma le_sub_of_add_le_left (ha : add_le_cancellable a) (h : a + b ≤ c) : b ≤ c - a :=
ha $ h.trans le_add_sub
protected lemma le_sub_of_add_le_right (hb : add_le_cancellable b) (h : a + b ≤ c) : a ≤ c - b :=
hb.le_sub_of_add_le_left $ by rwa [add_comm]
protected lemma lt_add_of_sub_lt_left (hb : add_le_cancellable b) (h : a - b < c) : a < b + c :=
begin
rw [lt_iff_le_and_ne, ← sub_le_iff_left],
refine ⟨h.le, _⟩,
rintro rfl,
simpa [hb] using h,
end
protected lemma lt_add_of_sub_lt_right (hc : add_le_cancellable c) (h : a - c < b) : a < b + c :=
begin
rw [lt_iff_le_and_ne, ← sub_le_iff_right],
refine ⟨h.le, _⟩,
rintro rfl,
simpa [hc] using h,
end
end add_le_cancellable
/-! Lemmas where addition is order-reflecting. -/
section contra
variable [contravariant_class α α (+) (≤)]
lemma le_add_sub_swap : a ≤ b + a - b :=
contravariant.add_le_cancellable.le_add_sub_swap
lemma le_add_sub' : a ≤ a + b - b :=
contravariant.add_le_cancellable.le_add_sub
lemma sub_eq_of_eq_add'' (h : a = c + b) : a - b = c :=
contravariant.add_le_cancellable.sub_eq_of_eq_add h
lemma eq_sub_of_add_eq'' (h : a + c = b) : a = b - c :=
contravariant.add_le_cancellable.eq_sub_of_add_eq h
@[simp]
lemma add_sub_cancel_right : a + b - b = a :=
contravariant.add_le_cancellable.add_sub_cancel_right
@[simp]
lemma add_sub_cancel_left : a + b - a = b :=
contravariant.add_le_cancellable.add_sub_cancel_left
lemma le_sub_of_add_le_left' (h : a + b ≤ c) : b ≤ c - a :=
contravariant.add_le_cancellable.le_sub_of_add_le_left h
lemma le_sub_of_add_le_right' (h : a + b ≤ c) : a ≤ c - b :=
contravariant.add_le_cancellable.le_sub_of_add_le_right h
lemma lt_add_of_sub_lt_left' (h : a - b < c) : a < b + c :=
contravariant.add_le_cancellable.lt_add_of_sub_lt_left h
lemma lt_add_of_sub_lt_right' (h : a - c < b) : a < b + c :=
contravariant.add_le_cancellable.lt_add_of_sub_lt_right h
end contra
section both
variables [covariant_class α α (+) (≤)] [contravariant_class α α (+) (≤)]
lemma add_sub_add_right_eq_sub' : (a + c) - (b + c) = a - b :=
begin
apply le_antisymm,
{ rw [sub_le_iff_left, add_right_comm], exact add_le_add_right le_add_sub c },
{ rw [sub_le_iff_left, add_comm b],
apply le_of_add_le_add_right,
rw [add_assoc],
exact le_sub_add }
end
lemma add_sub_add_eq_sub_left' (a b c : α) : (a + b) - (a + c) = b - c :=
by rw [add_comm a b, add_comm a c, add_sub_add_right_eq_sub']
end both
end ordered_add_comm_monoid
/-! Lemmas in a linearly ordered monoid. -/
section linear_order
variables {a b c d : α} [linear_order α] [add_comm_monoid α] [has_sub α] [has_ordered_sub α]
/-- See `lt_of_sub_lt_sub_right_of_le` for a weaker statement in a partial order. -/
lemma lt_of_sub_lt_sub_right (h : a - c < b - c) : a < b :=
lt_imp_lt_of_le_imp_le (λ h, sub_le_sub_right' h c) h
section cov
variable [covariant_class α α (+) (≤)]
/-- See `lt_of_sub_lt_sub_left_of_le` for a weaker statement in a partial order. -/
lemma lt_of_sub_lt_sub_left (h : a - b < a - c) : c < b :=
lt_imp_lt_of_le_imp_le (λ h, sub_le_sub_left' h a) h
end cov
end linear_order
/-! Lemmas in a canonically ordered monoid. -/
section canonically_ordered_add_monoid
variables [canonically_ordered_add_monoid α] [has_sub α] [has_ordered_sub α] {a b c d : α}
lemma add_sub_cancel_of_le (h : a ≤ b) : a + (b - a) = b :=
begin
refine le_antisymm _ le_add_sub,
obtain ⟨c, rfl⟩ := le_iff_exists_add.1 h,
exact add_le_add_left add_sub_le_left a,
end
lemma sub_add_cancel_of_le (h : a ≤ b) : b - a + a = b :=
by { rw [add_comm], exact add_sub_cancel_of_le h }
lemma add_sub_cancel_iff_le : a + (b - a) = b ↔ a ≤ b :=
⟨λ h, le_iff_exists_add.mpr ⟨b - a, h.symm⟩, add_sub_cancel_of_le⟩
lemma sub_add_cancel_iff_le : b - a + a = b ↔ a ≤ b :=
by { rw [add_comm], exact add_sub_cancel_iff_le }
lemma add_le_of_le_sub_right_of_le (h : b ≤ c) (h2 : a ≤ c - b) : a + b ≤ c :=
(add_le_add_right h2 b).trans_eq $ sub_add_cancel_of_le h
lemma add_le_of_le_sub_left_of_le (h : a ≤ c) (h2 : b ≤ c - a) : a + b ≤ c :=
(add_le_add_left h2 a).trans_eq $ add_sub_cancel_of_le h
lemma sub_le_sub_iff_right' (h : c ≤ b) : a - c ≤ b - c ↔ a ≤ b :=
by rw [sub_le_iff_right, sub_add_cancel_of_le h]
lemma sub_left_inj' (h1 : c ≤ a) (h2 : c ≤ b) : a - c = b - c ↔ a = b :=
by simp_rw [le_antisymm_iff, sub_le_sub_iff_right' h1, sub_le_sub_iff_right' h2]
/-- See `lt_of_sub_lt_sub_right` for a stronger statement in a linear order. -/
lemma lt_of_sub_lt_sub_right_of_le (h : c ≤ b) (h2 : a - c < b - c) : a < b :=
by { refine ((sub_le_sub_iff_right' h).mp h2.le).lt_of_ne _, rintro rfl, exact h2.false }
lemma sub_eq_zero_iff_le : a - b = 0 ↔ a ≤ b :=
by rw [← nonpos_iff_eq_zero, sub_le_iff_left, add_zero]
@[simp] lemma sub_self' : a - a = 0 :=
sub_eq_zero_iff_le.mpr le_rfl
@[simp] lemma sub_le_self' : a - b ≤ a :=
sub_le_iff_left.mpr $ le_add_left le_rfl
@[simp] lemma sub_zero' : a - 0 = a :=
le_antisymm sub_le_self' $ le_add_sub.trans_eq $ zero_add _
@[simp] lemma zero_sub' : 0 - a = 0 :=
sub_eq_zero_iff_le.mpr $ zero_le a
lemma sub_self_add (a b : α) : a - (a + b) = 0 :=
by { rw [sub_eq_zero_iff_le], apply self_le_add_right }
lemma sub_inj_left (h₁ : a ≤ b) (h₂ : a ≤ c) (h₃ : b - a = c - a) : b = c :=
by rw [← sub_add_cancel_of_le h₁, ← sub_add_cancel_of_le h₂, h₃]
lemma sub_pos_iff_not_le : 0 < a - b ↔ ¬ a ≤ b :=
by rw [pos_iff_ne_zero, ne.def, sub_eq_zero_iff_le]
lemma sub_pos_of_lt' (h : a < b) : 0 < b - a :=
sub_pos_iff_not_le.mpr h.not_le
lemma sub_add_sub_cancel'' (hab : b ≤ a) (hbc : c ≤ b) : (a - b) + (b - c) = a - c :=
begin
convert sub_add_cancel_of_le (sub_le_sub_right' hab c) using 2,
rw [sub_sub', add_sub_cancel_of_le hbc],
end
lemma sub_sub_sub_cancel_right' (h : c ≤ b) : (a - c) - (b - c) = a - b :=
by rw [sub_sub', add_sub_cancel_of_le h]
/-! Lemmas that assume that an element is `add_le_cancellable`. -/
namespace add_le_cancellable
protected lemma eq_sub_iff_add_eq_of_le (hc : add_le_cancellable c) (h : c ≤ b) :
a = b - c ↔ a + c = b :=
begin
split,
{ rintro rfl, exact sub_add_cancel_of_le h },
{ rintro rfl, exact (hc.add_sub_cancel_right).symm }
end
protected lemma sub_eq_iff_eq_add_of_le (hb : add_le_cancellable b) (h : b ≤ a) :
a - b = c ↔ a = c + b :=
by rw [eq_comm, hb.eq_sub_iff_add_eq_of_le h, eq_comm]
protected lemma add_sub_assoc_of_le (hc : add_le_cancellable c) (h : c ≤ b) (a : α) :
a + b - c = a + (b - c) :=
by conv_lhs { rw [← add_sub_cancel_of_le h, add_comm c, ← add_assoc,
hc.add_sub_cancel_right] }
protected lemma sub_add_eq_add_sub (hb : add_le_cancellable b) (h : b ≤ a) :
a - b + c = a + c - b :=
by rw [add_comm a, hb.add_sub_assoc_of_le h, add_comm]
protected lemma sub_sub_assoc (hbc : add_le_cancellable (b - c)) (h₁ : b ≤ a) (h₂ : c ≤ b) :
a - (b - c) = a - b + c :=
by rw [hbc.sub_eq_iff_eq_add_of_le (sub_le_self'.trans h₁), add_assoc,
add_sub_cancel_of_le h₂, sub_add_cancel_of_le h₁]
protected lemma le_sub_iff_left (ha : add_le_cancellable a) (h : a ≤ c) : b ≤ c - a ↔ a + b ≤ c :=
⟨add_le_of_le_sub_left_of_le h, ha.le_sub_of_add_le_left⟩
protected lemma le_sub_iff_right (ha : add_le_cancellable a) (h : a ≤ c) : b ≤ c - a ↔ b + a ≤ c :=
by { rw [add_comm], exact ha.le_sub_iff_left h }
protected lemma sub_lt_iff_left (hb : add_le_cancellable b) (hba : b ≤ a) :
a - b < c ↔ a < b + c :=
begin
refine ⟨hb.lt_add_of_sub_lt_left, _⟩,
intro h, refine (sub_le_iff_left.mpr h.le).lt_of_ne _,
rintro rfl, exact h.ne' (add_sub_cancel_of_le hba)
end
protected lemma sub_lt_iff_right (hb : add_le_cancellable b) (hba : b ≤ a) :
a - b < c ↔ a < c + b :=
by { rw [add_comm], exact hb.sub_lt_iff_left hba }
protected lemma lt_sub_of_add_lt_right (hc : add_le_cancellable c) (h : a + c < b) : a < b - c :=
begin
apply lt_of_le_of_ne,
{ rw [← add_sub_cancel_of_le h.le, add_right_comm, add_assoc],
rw [hc.add_sub_assoc_of_le], refine le_self_add, refine le_add_self },
{ rintro rfl, apply h.not_le, exact le_sub_add }
end
protected lemma lt_sub_of_add_lt_left (ha : add_le_cancellable a) (h : a + c < b) : c < b - a :=
by { apply ha.lt_sub_of_add_lt_right, rwa add_comm }
protected lemma sub_lt_iff_sub_lt (hb : add_le_cancellable b) (hc : add_le_cancellable c)
(h₁ : b ≤ a) (h₂ : c ≤ a) : a - b < c ↔ a - c < b :=
by rw [hb.sub_lt_iff_left h₁, hc.sub_lt_iff_right h₂]
protected lemma le_sub_iff_le_sub (ha : add_le_cancellable a) (hc : add_le_cancellable c)
(h₁ : a ≤ b) (h₂ : c ≤ b) : a ≤ b - c ↔ c ≤ b - a :=
by rw [ha.le_sub_iff_left h₁, hc.le_sub_iff_right h₂]
protected lemma lt_sub_iff_right_of_le (hc : add_le_cancellable c) (h : c ≤ b) :
a < b - c ↔ a + c < b :=
begin
refine ⟨_, hc.lt_sub_of_add_lt_right⟩,
intro h2,
refine (add_le_of_le_sub_right_of_le h h2.le).lt_of_ne _,
rintro rfl,
apply h2.not_le,
rw [hc.add_sub_cancel_right]
end
protected lemma lt_sub_iff_left_of_le (hc : add_le_cancellable c) (h : c ≤ b) :
a < b - c ↔ c + a < b :=
by { rw [add_comm], exact hc.lt_sub_iff_right_of_le h }
protected lemma lt_of_sub_lt_sub_left_of_le (hb : add_le_cancellable b) (hca : c ≤ a)
(h : a - b < a - c) : c < b :=
begin
conv_lhs at h { rw [← sub_add_cancel_of_le hca] },
exact lt_of_add_lt_add_left (hb.lt_add_of_sub_lt_right h),
end
protected lemma sub_le_sub_iff_left (ha : add_le_cancellable a) (hc : add_le_cancellable c)
(h : c ≤ a) : a - b ≤ a - c ↔ c ≤ b :=
begin
refine ⟨_, λ h, sub_le_sub_left' h a⟩,
rw [sub_le_iff_left, ← hc.add_sub_assoc_of_le h,
hc.le_sub_iff_right (h.trans le_add_self), add_comm b],
apply ha,
end
protected lemma sub_right_inj (ha : add_le_cancellable a) (hb : add_le_cancellable b)
(hc : add_le_cancellable c) (hba : b ≤ a) (hca : c ≤ a) : a - b = a - c ↔ b = c :=
by simp_rw [le_antisymm_iff, ha.sub_le_sub_iff_left hb hba, ha.sub_le_sub_iff_left hc hca, and_comm]
protected lemma sub_lt_sub_right_of_le (hc : add_le_cancellable c) (h : c ≤ a) (h2 : a < b) :
a - c < b - c :=
by { apply hc.lt_sub_of_add_lt_left, rwa [add_sub_cancel_of_le h] }
protected lemma sub_inj_right (hab : add_le_cancellable (a - b)) (h₁ : b ≤ a) (h₂ : c ≤ a)
(h₃ : a - b = a - c) : b = c :=
by { rw ← hab.inj, rw [sub_add_cancel_of_le h₁, h₃, sub_add_cancel_of_le h₂] }
protected lemma sub_lt_sub_iff_left_of_le_of_le (hb : add_le_cancellable b)
(hab : add_le_cancellable (a - b)) (h₁ : b ≤ a) (h₂ : c ≤ a) : a - b < a - c ↔ c < b :=
begin
refine ⟨hb.lt_of_sub_lt_sub_left_of_le h₂, _⟩,
intro h, refine (sub_le_sub_left' h.le _).lt_of_ne _,
rintro h2, exact h.ne' (hab.sub_inj_right h₁ h₂ h2)
end
@[simp] protected lemma add_sub_sub_cancel (hac : add_le_cancellable (a - c)) (h : c ≤ a) :
(a + b) - (a - c) = b + c :=
(hac.sub_eq_iff_eq_add_of_le $ sub_le_self'.trans le_self_add).mpr $
by rw [add_assoc, add_sub_cancel_of_le h, add_comm]
protected lemma sub_sub_cancel_of_le (hba : add_le_cancellable (b - a)) (h : a ≤ b) :
b - (b - a) = a :=
by rw [hba.sub_eq_iff_eq_add_of_le sub_le_self', add_sub_cancel_of_le h]
end add_le_cancellable
section contra
/-! Lemmas where addition is order-reflecting. -/
variable [contravariant_class α α (+) (≤)]
lemma eq_sub_iff_add_eq_of_le (h : c ≤ b) : a = b - c ↔ a + c = b :=
contravariant.add_le_cancellable.eq_sub_iff_add_eq_of_le h
lemma sub_eq_iff_eq_add_of_le (h : b ≤ a) : a - b = c ↔ a = c + b :=
contravariant.add_le_cancellable.sub_eq_iff_eq_add_of_le h
/-- See `add_sub_le_assoc` for an inequality. -/
lemma add_sub_assoc_of_le (h : c ≤ b) (a : α) : a + b - c = a + (b - c) :=
contravariant.add_le_cancellable.add_sub_assoc_of_le h a
lemma sub_add_eq_add_sub' (h : b ≤ a) : a - b + c = a + c - b :=
contravariant.add_le_cancellable.sub_add_eq_add_sub h
lemma sub_sub_assoc (h₁ : b ≤ a) (h₂ : c ≤ b) : a - (b - c) = a - b + c :=
contravariant.add_le_cancellable.sub_sub_assoc h₁ h₂
lemma le_sub_iff_left (h : a ≤ c) : b ≤ c - a ↔ a + b ≤ c :=
contravariant.add_le_cancellable.le_sub_iff_left h
lemma le_sub_iff_right (h : a ≤ c) : b ≤ c - a ↔ b + a ≤ c :=
contravariant.add_le_cancellable.le_sub_iff_right h
lemma sub_lt_iff_left (hbc : b ≤ a) : a - b < c ↔ a < b + c :=
contravariant.add_le_cancellable.sub_lt_iff_left hbc
lemma sub_lt_iff_right (hbc : b ≤ a) : a - b < c ↔ a < c + b :=
contravariant.add_le_cancellable.sub_lt_iff_right hbc
/-- This lemma (and some of its corollaries also holds for `ennreal`,
but this proof doesn't work for it.
Maybe we should add this lemma as field to `has_ordered_sub`? -/
lemma lt_sub_of_add_lt_right (h : a + c < b) : a < b - c :=
contravariant.add_le_cancellable.lt_sub_of_add_lt_right h
lemma lt_sub_of_add_lt_left (h : a + c < b) : c < b - a :=
contravariant.add_le_cancellable.lt_sub_of_add_lt_left h
lemma sub_lt_iff_sub_lt (h₁ : b ≤ a) (h₂ : c ≤ a) : a - b < c ↔ a - c < b :=
contravariant.add_le_cancellable.sub_lt_iff_sub_lt contravariant.add_le_cancellable h₁ h₂
lemma le_sub_iff_le_sub (h₁ : a ≤ b) (h₂ : c ≤ b) : a ≤ b - c ↔ c ≤ b - a :=
contravariant.add_le_cancellable.le_sub_iff_le_sub contravariant.add_le_cancellable h₁ h₂
/-- See `lt_sub_iff_right` for a stronger statement in a linear order. -/
lemma lt_sub_iff_right_of_le (h : c ≤ b) : a < b - c ↔ a + c < b :=
contravariant.add_le_cancellable.lt_sub_iff_right_of_le h
/-- See `lt_sub_iff_left` for a stronger statement in a linear order. -/
lemma lt_sub_iff_left_of_le (h : c ≤ b) : a < b - c ↔ c + a < b :=
contravariant.add_le_cancellable.lt_sub_iff_left_of_le h
/-- See `lt_of_sub_lt_sub_left` for a stronger statement in a linear order. -/
lemma lt_of_sub_lt_sub_left_of_le (hca : c ≤ a) (h : a - b < a - c) : c < b :=
contravariant.add_le_cancellable.lt_of_sub_lt_sub_left_of_le hca h
lemma sub_le_sub_iff_left' (h : c ≤ a) : a - b ≤ a - c ↔ c ≤ b :=
contravariant.add_le_cancellable.sub_le_sub_iff_left contravariant.add_le_cancellable h
lemma sub_right_inj' (hba : b ≤ a) (hca : c ≤ a) : a - b = a - c ↔ b = c :=
contravariant.add_le_cancellable.sub_right_inj contravariant.add_le_cancellable
contravariant.add_le_cancellable hba hca
lemma sub_lt_sub_right_of_le (h : c ≤ a) (h2 : a < b) : a - c < b - c :=
contravariant.add_le_cancellable.sub_lt_sub_right_of_le h h2
lemma sub_inj_right (h₁ : b ≤ a) (h₂ : c ≤ a) (h₃ : a - b = a - c) : b = c :=
contravariant.add_le_cancellable.sub_inj_right h₁ h₂ h₃
/-- See `sub_lt_sub_iff_left_of_le` for a stronger statement in a linear order. -/
lemma sub_lt_sub_iff_left_of_le_of_le (h₁ : b ≤ a) (h₂ : c ≤ a) : a - b < a - c ↔ c < b :=
contravariant.add_le_cancellable.sub_lt_sub_iff_left_of_le_of_le
contravariant.add_le_cancellable h₁ h₂
@[simp] lemma add_sub_sub_cancel' (h : c ≤ a) : (a + b) - (a - c) = b + c :=
contravariant.add_le_cancellable.add_sub_sub_cancel h
/-- See `sub_sub_le` for an inequality. -/
lemma sub_sub_cancel_of_le (h : a ≤ b) : b - (b - a) = a :=
contravariant.add_le_cancellable.sub_sub_cancel_of_le h
end contra
end canonically_ordered_add_monoid
/-! Lemmas in a linearly canonically ordered monoid. -/
section canonically_linear_ordered_add_monoid
variables [canonically_linear_ordered_add_monoid α] [has_sub α] [has_ordered_sub α] {a b c d : α}
lemma sub_pos_iff_lt : 0 < a - b ↔ b < a :=
by rw [sub_pos_iff_not_le, not_le]
lemma sub_eq_sub_min (a b : α) : a - b = a - min a b :=
begin
cases le_total a b with h h,
{ rw [min_eq_left h, sub_self', sub_eq_zero_iff_le.mpr h] },
{ rw [min_eq_right h] },
end
namespace add_le_cancellable
protected lemma lt_sub_iff_right (hc : add_le_cancellable c) : a < b - c ↔ a + c < b :=
⟨lt_imp_lt_of_le_imp_le sub_le_iff_right.mpr, hc.lt_sub_of_add_lt_right⟩
protected lemma lt_sub_iff_left (hc : add_le_cancellable c) : a < b - c ↔ c + a < b :=
⟨lt_imp_lt_of_le_imp_le sub_le_iff_left.mpr, hc.lt_sub_of_add_lt_left⟩
protected lemma sub_lt_sub_iff_right (hc : add_le_cancellable c) (h : c ≤ a) :
a - c < b - c ↔ a < b :=
by rw [hc.lt_sub_iff_left, add_sub_cancel_of_le h]
protected lemma lt_sub_iff_lt_sub (ha : add_le_cancellable a) (hc : add_le_cancellable c) :
a < b - c ↔ c < b - a :=
by rw [hc.lt_sub_iff_left, ha.lt_sub_iff_right]
protected lemma sub_lt_self (ha : add_le_cancellable a) (hb : add_le_cancellable b)
(h₁ : 0 < a) (h₂ : 0 < b) : a - b < a :=
begin
refine sub_le_self'.lt_of_ne _,
intro h,
rw [← h, sub_pos_iff_lt] at h₁,
have := h.ge,
rw [hb.le_sub_iff_left h₁.le, ha.add_le_iff_nonpos_left] at this,
exact h₂.not_le this,
end
protected lemma sub_lt_self_iff (ha : add_le_cancellable a) (hb : add_le_cancellable b) :
a - b < a ↔ 0 < a ∧ 0 < b :=
begin
refine ⟨_, λ h, ha.sub_lt_self hb h.1 h.2⟩,
intro h,
refine ⟨(zero_le _).trans_lt h, (zero_le b).lt_of_ne _⟩,
rintro rfl,
rw [sub_zero'] at h,
exact h.false
end
/-- See `lt_sub_iff_left_of_le_of_le` for a weaker statement in a partial order. -/
protected lemma sub_lt_sub_iff_left_of_le (ha : add_le_cancellable a) (hb : add_le_cancellable b)
(h : b ≤ a) : a - b < a - c ↔ c < b :=
lt_iff_lt_of_le_iff_le $ ha.sub_le_sub_iff_left hb h
end add_le_cancellable
section contra
variable [contravariant_class α α (+) (≤)]
/-- See `lt_sub_iff_right_of_le` for a weaker statement in a partial order.
This lemma also holds for `ennreal`, but we need a different proof for that. -/
lemma lt_sub_iff_right : a < b - c ↔ a + c < b :=
contravariant.add_le_cancellable.lt_sub_iff_right
/-- See `lt_sub_iff_left_of_le` for a weaker statement in a partial order.
This lemma also holds for `ennreal`, but we need a different proof for that. -/
lemma lt_sub_iff_left : a < b - c ↔ c + a < b :=
contravariant.add_le_cancellable.lt_sub_iff_left
/-- This lemma also holds for `ennreal`, but we need a different proof for that. -/
lemma sub_lt_sub_iff_right' (h : c ≤ a) : a - c < b - c ↔ a < b :=
contravariant.add_le_cancellable.sub_lt_sub_iff_right h
lemma lt_sub_iff_lt_sub : a < b - c ↔ c < b - a :=
contravariant.add_le_cancellable.lt_sub_iff_lt_sub contravariant.add_le_cancellable
lemma sub_lt_self' (h₁ : 0 < a) (h₂ : 0 < b) : a - b < a :=
contravariant.add_le_cancellable.sub_lt_self contravariant.add_le_cancellable h₁ h₂
lemma sub_lt_self_iff' : a - b < a ↔ 0 < a ∧ 0 < b :=
contravariant.add_le_cancellable.sub_lt_self_iff contravariant.add_le_cancellable
/-- See `lt_sub_iff_left_of_le_of_le` for a weaker statement in a partial order. -/
lemma sub_lt_sub_iff_left_of_le (h : b ≤ a) : a - b < a - c ↔ c < b :=
contravariant.add_le_cancellable.sub_lt_sub_iff_left_of_le contravariant.add_le_cancellable h
end contra
/-! Lemmas about `max` and `min`. -/
lemma sub_add_eq_max : a - b + b = max a b :=
begin
cases le_total a b with h h,
{ rw [max_eq_right h, sub_eq_zero_iff_le.mpr h, zero_add] },
{ rw [max_eq_left h, sub_add_cancel_of_le h] }
end
lemma add_sub_eq_max : a + (b - a) = max a b :=
by rw [add_comm, max_comm, sub_add_eq_max]
lemma sub_min : a - min a b = a - b :=
begin
cases le_total a b with h h,
{ rw [min_eq_left h, sub_self', sub_eq_zero_iff_le.mpr h] },
{ rw [min_eq_right h] }
end
lemma sub_add_min : a - b + min a b = a :=
by { rw [← sub_min, sub_add_cancel_of_le], apply min_le_left }
end canonically_linear_ordered_add_monoid
|
8ee0b6c36706ce1d5cb34f45ae2085f1717492e1 | 86f6f4f8d827a196a32bfc646234b73328aeb306 | /examples/basics/unnamed_2030.lean | f679f590b075c312d0d70b77a77b7e87a2984669 | [] | no_license | jamescheuk91/mathematics_in_lean | 09f1f87d2b0dce53464ff0cbe592c568ff59cf5e | 4452499264e2975bca2f42565c0925506ba5dda3 | refs/heads/master | 1,679,716,410,967 | 1,613,957,947,000 | 1,613,957,947,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 240 | lean | import topology.metric_space.basic
variables {X : Type*} [metric_space X]
variables x y z : X
#check (dist_self x : dist x x = 0)
#check (dist_comm x y : dist x y = dist y x)
#check (dist_triangle x y z : dist x z ≤ dist x y + dist y z) |
7b4e28d6afd9116fd8c33d882cfe01656931191c | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/algebra/order/archimedean.lean | 3fa825a3a4457cf9ed776167f8520a03e13469ed | [
"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 | 15,121 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
-/
import data.int.least_greatest
import data.rat.floor
/-!
# Archimedean groups and fields.
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
This file defines the archimedean property for ordered groups and proves several results connected
to this notion. Being archimedean means that for all elements `x` and `y>0` there exists a natural
number `n` such that `x ≤ n • y`.
## Main definitions
* `archimedean` is a typeclass for an ordered additive commutative monoid to have the archimedean
property.
* `archimedean.floor_ring` defines a floor function on an archimedean linearly ordered ring making
it into a `floor_ring`.
## Main statements
* `ℕ`, `ℤ`, and `ℚ` are archimedean.
-/
open int set
variables {α : Type*}
/-- An ordered additive commutative monoid is called `archimedean` if for any two elements `x`, `y`
such that `0 < y` there exists a natural number `n` such that `x ≤ n • y`. -/
class archimedean (α) [ordered_add_comm_monoid α] : Prop :=
(arch : ∀ (x : α) {y}, 0 < y → ∃ n : ℕ, x ≤ n • y)
instance order_dual.archimedean [ordered_add_comm_group α] [archimedean α] : archimedean αᵒᵈ :=
⟨λ x y hy, let ⟨n, hn⟩ := archimedean.arch (-x : α) (neg_pos.2 hy) in
⟨n, by rwa [neg_nsmul, neg_le_neg_iff] at hn⟩⟩
section linear_ordered_add_comm_group
variables [linear_ordered_add_comm_group α] [archimedean α]
/-- An archimedean decidable linearly ordered `add_comm_group` has a version of the floor: for
`a > 0`, any `g` in the group lies between some two consecutive multiples of `a`. -/
lemma exists_unique_zsmul_near_of_pos {a : α} (ha : 0 < a) (g : α) :
∃! k : ℤ, k • a ≤ g ∧ g < (k + 1) • a :=
begin
let s : set ℤ := {n : ℤ | n • a ≤ g},
obtain ⟨k, hk : -g ≤ k • a⟩ := archimedean.arch (-g) ha,
have h_ne : s.nonempty := ⟨-k, by simpa using neg_le_neg hk⟩,
obtain ⟨k, hk⟩ := archimedean.arch g ha,
have h_bdd : ∀ n ∈ s, n ≤ (k : ℤ),
{ assume n hn,
apply (zsmul_le_zsmul_iff ha).mp,
rw ← coe_nat_zsmul at hk,
exact le_trans hn hk },
obtain ⟨m, hm, hm'⟩ := int.exists_greatest_of_bdd ⟨k, h_bdd⟩ h_ne,
have hm'' : g < (m + 1) • a,
{ contrapose! hm', exact ⟨m + 1, hm', lt_add_one _⟩, },
refine ⟨m, ⟨hm, hm''⟩, λ n hn, (hm' n hn.1).antisymm $ int.le_of_lt_add_one _⟩,
rw ← zsmul_lt_zsmul_iff ha,
exact lt_of_le_of_lt hm hn.2
end
lemma exists_unique_zsmul_near_of_pos' {a : α} (ha : 0 < a) (g : α) :
∃! k : ℤ, 0 ≤ g - k • a ∧ g - k • a < a :=
by simpa only [sub_nonneg, add_zsmul, one_zsmul, sub_lt_iff_lt_add']
using exists_unique_zsmul_near_of_pos ha g
lemma exists_unique_sub_zsmul_mem_Ico {a : α} (ha : 0 < a) (b c : α) :
∃! m : ℤ, b - m • a ∈ set.Ico c (c + a) :=
by simpa only [mem_Ico, le_sub_iff_add_le, zero_add, add_comm c, sub_lt_iff_lt_add', add_assoc]
using exists_unique_zsmul_near_of_pos' ha (b - c)
lemma exists_unique_add_zsmul_mem_Ico {a : α} (ha : 0 < a) (b c : α) :
∃! m : ℤ, b + m • a ∈ set.Ico c (c + a) :=
(equiv.neg ℤ).bijective.exists_unique_iff.2 $
by simpa only [equiv.neg_apply, neg_zsmul, ← sub_eq_add_neg]
using exists_unique_sub_zsmul_mem_Ico ha b c
lemma exists_unique_add_zsmul_mem_Ioc {a : α} (ha : 0 < a) (b c : α) :
∃! m : ℤ, b + m • a ∈ set.Ioc c (c + a) :=
(equiv.add_right (1 : ℤ)).bijective.exists_unique_iff.2 $
by simpa only [add_one_zsmul, sub_lt_iff_lt_add', le_sub_iff_add_le', ← add_assoc, and.comm,
mem_Ioc, equiv.coe_add_right, add_le_add_iff_right]
using exists_unique_zsmul_near_of_pos ha (c - b)
lemma exists_unique_sub_zsmul_mem_Ioc {a : α} (ha : 0 < a) (b c : α) :
∃! m : ℤ, b - m • a ∈ set.Ioc c (c + a) :=
(equiv.neg ℤ).bijective.exists_unique_iff.2 $
by simpa only [equiv.neg_apply, neg_zsmul, sub_neg_eq_add]
using exists_unique_add_zsmul_mem_Ioc ha b c
end linear_ordered_add_comm_group
theorem exists_nat_gt [strict_ordered_semiring α] [archimedean α] (x : α) : ∃ n : ℕ, x < n :=
let ⟨n, h⟩ := archimedean.arch x zero_lt_one in
⟨n+1, lt_of_le_of_lt (by rwa ← nsmul_one)
(nat.cast_lt.2 (nat.lt_succ_self _))⟩
theorem exists_nat_ge [strict_ordered_semiring α] [archimedean α] (x : α) :
∃ n : ℕ, x ≤ n :=
begin
nontriviality α,
exact (exists_nat_gt x).imp (λ n, le_of_lt)
end
lemma add_one_pow_unbounded_of_pos [strict_ordered_semiring α] [archimedean α] (x : α) {y : α}
(hy : 0 < y) :
∃ n : ℕ, x < (y + 1) ^ n :=
have 0 ≤ 1 + y, from add_nonneg zero_le_one hy.le,
let ⟨n, h⟩ := archimedean.arch x hy in
⟨n, calc x ≤ n • y : h
... = n * y : nsmul_eq_mul _ _
... < 1 + n * y : lt_one_add _
... ≤ (1 + y) ^ n : one_add_mul_le_pow' (mul_nonneg hy.le hy.le) (mul_nonneg this this)
(add_nonneg zero_le_two hy.le) _
... = (y + 1) ^ n : by rw [add_comm]⟩
section strict_ordered_ring
variables [strict_ordered_ring α] [archimedean α]
lemma pow_unbounded_of_one_lt (x : α) {y : α} (hy1 : 1 < y) :
∃ n : ℕ, x < y ^ n :=
sub_add_cancel y 1 ▸ add_one_pow_unbounded_of_pos _ (sub_pos.2 hy1)
theorem exists_int_gt (x : α) : ∃ n : ℤ, x < n :=
let ⟨n, h⟩ := exists_nat_gt x in ⟨n, by rwa int.cast_coe_nat⟩
theorem exists_int_lt (x : α) : ∃ n : ℤ, (n : α) < x :=
let ⟨n, h⟩ := exists_int_gt (-x) in ⟨-n, by rw int.cast_neg; exact neg_lt.1 h⟩
theorem exists_floor (x : α) :
∃ (fl : ℤ), ∀ (z : ℤ), z ≤ fl ↔ (z : α) ≤ x :=
begin
haveI := classical.prop_decidable,
have : ∃ (ub : ℤ), (ub:α) ≤ x ∧ ∀ (z : ℤ), (z:α) ≤ x → z ≤ ub :=
int.exists_greatest_of_bdd
(let ⟨n, hn⟩ := exists_int_gt x in ⟨n, λ z h',
int.cast_le.1 $ le_trans h' $ le_of_lt hn⟩)
(let ⟨n, hn⟩ := exists_int_lt x in ⟨n, le_of_lt hn⟩),
refine this.imp (λ fl h z, _),
cases h with h₁ h₂,
exact ⟨λ h, le_trans (int.cast_le.2 h) h₁, h₂ z⟩,
end
end strict_ordered_ring
section linear_ordered_ring
variables [linear_ordered_ring α] [archimedean α]
/-- Every x greater than or equal to 1 is between two successive
natural-number powers of every y greater than one. -/
lemma exists_nat_pow_near {x : α} {y : α} (hx : 1 ≤ x) (hy : 1 < y) :
∃ n : ℕ, y ^ n ≤ x ∧ x < y ^ (n + 1) :=
have h : ∃ n : ℕ, x < y ^ n, from pow_unbounded_of_one_lt _ hy,
by classical; exact let n := nat.find h in
have hn : x < y ^ n, from nat.find_spec h,
have hnp : 0 < n, from pos_iff_ne_zero.2 (λ hn0,
by rw [hn0, pow_zero] at hn; exact (not_le_of_gt hn hx)),
have hnsp : nat.pred n + 1 = n, from nat.succ_pred_eq_of_pos hnp,
have hltn : nat.pred n < n, from nat.pred_lt (ne_of_gt hnp),
⟨nat.pred n, le_of_not_lt (nat.find_min h hltn), by rwa hnsp⟩
end linear_ordered_ring
section linear_ordered_field
variables [linear_ordered_field α] [archimedean α] {x y ε : α}
/-- Every positive `x` is between two successive integer powers of
another `y` greater than one. This is the same as `exists_mem_Ioc_zpow`,
but with ≤ and < the other way around. -/
lemma exists_mem_Ico_zpow (hx : 0 < x) (hy : 1 < y) : ∃ n : ℤ, x ∈ Ico (y ^ n) (y ^ (n + 1)) :=
by classical; exact
let ⟨N, hN⟩ := pow_unbounded_of_one_lt x⁻¹ hy in
have he: ∃ m : ℤ, y ^ m ≤ x, from
⟨-N, le_of_lt (by { rw [zpow_neg y (↑N), zpow_coe_nat],
exact (inv_lt hx (lt_trans (inv_pos.2 hx) hN)).1 hN })⟩,
let ⟨M, hM⟩ := pow_unbounded_of_one_lt x hy in
have hb: ∃ b : ℤ, ∀ m, y ^ m ≤ x → m ≤ b, from
⟨M, λ m hm, le_of_not_lt (λ hlt, not_lt_of_ge
(zpow_le_of_le hy.le hlt.le)
(lt_of_le_of_lt hm (by rwa ← zpow_coe_nat at hM)))⟩,
let ⟨n, hn₁, hn₂⟩ := int.exists_greatest_of_bdd hb he in
⟨n, hn₁, lt_of_not_ge (λ hge, not_le_of_gt (int.lt_succ _) (hn₂ _ hge))⟩
/-- Every positive `x` is between two successive integer powers of
another `y` greater than one. This is the same as `exists_mem_Ico_zpow`,
but with ≤ and < the other way around. -/
lemma exists_mem_Ioc_zpow (hx : 0 < x) (hy : 1 < y) : ∃ n : ℤ, x ∈ Ioc (y ^ n) (y ^ (n + 1)) :=
let ⟨m, hle, hlt⟩ := exists_mem_Ico_zpow (inv_pos.2 hx) hy in
have hyp : 0 < y, from lt_trans zero_lt_one hy,
⟨-(m+1),
by rwa [zpow_neg, inv_lt (zpow_pos_of_pos hyp _) hx],
by rwa [neg_add, neg_add_cancel_right, zpow_neg,
le_inv hx (zpow_pos_of_pos hyp _)]⟩
/-- For any `y < 1` and any positive `x`, there exists `n : ℕ` with `y ^ n < x`. -/
lemma exists_pow_lt_of_lt_one (hx : 0 < x) (hy : y < 1) : ∃ n : ℕ, y ^ n < x :=
begin
by_cases y_pos : y ≤ 0,
{ use 1, simp only [pow_one], linarith, },
rw [not_le] at y_pos,
rcases pow_unbounded_of_one_lt (x⁻¹) (one_lt_inv y_pos hy) with ⟨q, hq⟩,
exact ⟨q, by rwa [inv_pow, inv_lt_inv hx (pow_pos y_pos _)] at hq⟩
end
/-- Given `x` and `y` between `0` and `1`, `x` is between two successive powers of `y`.
This is the same as `exists_nat_pow_near`, but for elements between `0` and `1` -/
lemma exists_nat_pow_near_of_lt_one (xpos : 0 < x) (hx : x ≤ 1) (ypos : 0 < y) (hy : y < 1) :
∃ n : ℕ, y ^ (n + 1) < x ∧ x ≤ y ^ n :=
begin
rcases exists_nat_pow_near (one_le_inv_iff.2 ⟨xpos, hx⟩) (one_lt_inv_iff.2 ⟨ypos, hy⟩)
with ⟨n, hn, h'n⟩,
refine ⟨n, _, _⟩,
{ rwa [inv_pow, inv_lt_inv xpos (pow_pos ypos _)] at h'n },
{ rwa [inv_pow, inv_le_inv (pow_pos ypos _) xpos] at hn }
end
lemma exists_rat_gt (x : α) : ∃ q : ℚ, x < q :=
let ⟨n, h⟩ := exists_nat_gt x in ⟨n, by rwa rat.cast_coe_nat⟩
theorem exists_rat_lt (x : α) : ∃ q : ℚ, (q : α) < x :=
let ⟨n, h⟩ := exists_int_lt x in ⟨n, by rwa rat.cast_coe_int⟩
theorem exists_rat_btwn {x y : α} (h : x < y) : ∃ q : ℚ, x < q ∧ (q:α) < y :=
begin
cases exists_nat_gt (y - x)⁻¹ with n nh,
cases exists_floor (x * n) with z zh,
refine ⟨(z + 1 : ℤ) / n, _⟩,
have n0' := (inv_pos.2 (sub_pos.2 h)).trans nh,
have n0 := nat.cast_pos.1 n0',
rw [rat.cast_div_of_ne_zero, rat.cast_coe_nat, rat.cast_coe_int, div_lt_iff n0'],
refine ⟨(lt_div_iff n0').2 $
(lt_iff_lt_of_le_iff_le (zh _)).1 (lt_add_one _), _⟩,
rw [int.cast_add, int.cast_one],
refine lt_of_le_of_lt (add_le_add_right ((zh _).1 le_rfl) _) _,
rwa [← lt_sub_iff_add_lt', ← sub_mul,
← div_lt_iff' (sub_pos.2 h), one_div],
{ rw [rat.coe_int_denom, nat.cast_one], exact one_ne_zero },
{ intro H, rw [rat.coe_nat_num, int.cast_coe_nat, nat.cast_eq_zero] at H, subst H, cases n0 },
{ rw [rat.coe_nat_denom, nat.cast_one], exact one_ne_zero }
end
lemma le_of_forall_rat_lt_imp_le (h : ∀ q : ℚ, (q : α) < x → (q : α) ≤ y) : x ≤ y :=
le_of_not_lt $ λ hyx, let ⟨q, hy, hx⟩ := exists_rat_btwn hyx in hy.not_le $ h _ hx
lemma le_of_forall_lt_rat_imp_le (h : ∀ q : ℚ, y < q → x ≤ q) : x ≤ y :=
le_of_not_lt $ λ hyx, let ⟨q, hy, hx⟩ := exists_rat_btwn hyx in hx.not_le $ h _ hy
lemma eq_of_forall_rat_lt_iff_lt (h : ∀ q : ℚ, (q : α) < x ↔ (q : α) < y) : x = y :=
(le_of_forall_rat_lt_imp_le $ λ q hq, ((h q).1 hq).le).antisymm $ le_of_forall_rat_lt_imp_le $
λ q hq, ((h q).2 hq).le
lemma eq_of_forall_lt_rat_iff_lt (h : ∀ q : ℚ, x < q ↔ y < q) : x = y :=
(le_of_forall_lt_rat_imp_le $ λ q hq, ((h q).2 hq).le).antisymm $ le_of_forall_lt_rat_imp_le $
λ q hq, ((h q).1 hq).le
theorem exists_nat_one_div_lt {ε : α} (hε : 0 < ε) : ∃ n : ℕ, 1 / (n + 1: α) < ε :=
begin
cases exists_nat_gt (1/ε) with n hn,
use n,
rw [div_lt_iff, ← div_lt_iff' hε],
{ apply hn.trans,
simp [zero_lt_one] },
{ exact n.cast_add_one_pos }
end
theorem exists_pos_rat_lt {x : α} (x0 : 0 < x) : ∃ q : ℚ, 0 < q ∧ (q : α) < x :=
by simpa only [rat.cast_pos] using exists_rat_btwn x0
lemma exists_rat_near (x : α) (ε0 : 0 < ε) : ∃ q : ℚ, |x - q| < ε :=
let ⟨q, h₁, h₂⟩ := exists_rat_btwn $ ((sub_lt_self_iff x).2 ε0).trans ((lt_add_iff_pos_left x).2 ε0)
in ⟨q, abs_sub_lt_iff.2 ⟨sub_lt_comm.1 h₁, sub_lt_iff_lt_add.2 h₂⟩⟩
end linear_ordered_field
section linear_ordered_field
variables [linear_ordered_field α]
lemma archimedean_iff_nat_lt : archimedean α ↔ ∀ x : α, ∃ n : ℕ, x < n :=
⟨@exists_nat_gt α _, λ H, ⟨λ x y y0,
(H (x / y)).imp $ λ n h, le_of_lt $
by rwa [div_lt_iff y0, ← nsmul_eq_mul] at h⟩⟩
lemma archimedean_iff_nat_le : archimedean α ↔ ∀ x : α, ∃ n : ℕ, x ≤ n :=
archimedean_iff_nat_lt.trans
⟨λ H x, (H x).imp $ λ _, le_of_lt,
λ H x, let ⟨n, h⟩ := H x in ⟨n+1,
lt_of_le_of_lt h (nat.cast_lt.2 (lt_add_one _))⟩⟩
lemma archimedean_iff_int_lt : archimedean α ↔ ∀ x : α, ∃ n : ℤ, x < n :=
⟨@exists_int_gt α _,
begin
rw archimedean_iff_nat_lt,
intros h x,
obtain ⟨n, h⟩ := h x,
refine ⟨n.to_nat, h.trans_le _⟩,
exact_mod_cast int.le_to_nat _,
end⟩
lemma archimedean_iff_int_le : archimedean α ↔ ∀ x : α, ∃ n : ℤ, x ≤ n :=
archimedean_iff_int_lt.trans
⟨λ H x, (H x).imp $ λ _, le_of_lt,
λ H x, let ⟨n, h⟩ := H x in ⟨n+1,
lt_of_le_of_lt h (int.cast_lt.2 (lt_add_one _))⟩⟩
lemma archimedean_iff_rat_lt : archimedean α ↔ ∀ x : α, ∃ q : ℚ, x < q :=
⟨@exists_rat_gt α _,
λ H, archimedean_iff_nat_lt.2 $ λ x,
let ⟨q, h⟩ := H x in
⟨⌈q⌉₊, lt_of_lt_of_le h $
by simpa only [rat.cast_coe_nat] using (@rat.cast_le α _ _ _).2 (nat.le_ceil _)⟩⟩
lemma archimedean_iff_rat_le : archimedean α ↔ ∀ x : α, ∃ q : ℚ, x ≤ q :=
archimedean_iff_rat_lt.trans
⟨λ H x, (H x).imp $ λ _, le_of_lt,
λ H x, let ⟨n, h⟩ := H x in ⟨n+1,
lt_of_le_of_lt h (rat.cast_lt.2 (lt_add_one _))⟩⟩
end linear_ordered_field
instance : archimedean ℕ :=
⟨λ n m m0, ⟨n, by simpa only [mul_one, nat.nsmul_eq_mul] using nat.mul_le_mul_left n m0⟩⟩
instance : archimedean ℤ :=
⟨λ n m m0, ⟨n.to_nat, le_trans (int.le_to_nat _) $
by simpa only [nsmul_eq_mul, zero_add, mul_one]
using mul_le_mul_of_nonneg_left (int.add_one_le_iff.2 m0) (int.coe_zero_le n.to_nat)⟩⟩
instance : archimedean ℚ :=
archimedean_iff_rat_le.2 $ λ q, ⟨q, by rw rat.cast_id⟩
/-- A linear ordered archimedean ring is a floor ring. This is not an `instance` because in some
cases we have a computable `floor` function. -/
noncomputable def archimedean.floor_ring (α) [linear_ordered_ring α] [archimedean α] :
floor_ring α :=
floor_ring.of_floor α (λ a, classical.some (exists_floor a))
(λ z a, (classical.some_spec (exists_floor a) z).symm)
/-- A linear ordered field that is a floor ring is archimedean. -/
@[priority 100] -- see Note [lower instance priority]
instance floor_ring.archimedean (α) [linear_ordered_field α] [floor_ring α] : archimedean α :=
begin
rw archimedean_iff_int_le,
exact λ x, ⟨⌈x⌉, int.le_ceil x⟩
end
|
54d4b01f5144af7a7951210b841c3691cbd96416 | 4efff1f47634ff19e2f786deadd394270a59ecd2 | /src/topology/metric_space/emetric_space.lean | 12a1d1ce88b3a87f77f9f6ad7fa98c206fa53406 | [
"Apache-2.0"
] | permissive | agjftucker/mathlib | d634cd0d5256b6325e3c55bb7fb2403548371707 | 87fe50de17b00af533f72a102d0adefe4a2285e8 | refs/heads/master | 1,625,378,131,941 | 1,599,166,526,000 | 1,599,166,526,000 | 160,748,509 | 0 | 0 | Apache-2.0 | 1,544,141,789,000 | 1,544,141,789,000 | null | UTF-8 | Lean | false | false | 39,246 | lean | /-
Copyright (c) 2015, 2017 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Robert Y. Lewis, Johannes Hölzl, Mario Carneiro, Sébastien Gouëzel
-/
import data.real.ennreal
import data.finset.intervals
import topology.uniform_space.uniform_embedding
import topology.uniform_space.pi
import topology.uniform_space.uniform_convergence
/-!
# Extended metric spaces
This file is devoted to the definition and study of `emetric_spaces`, i.e., metric
spaces in which the distance is allowed to take the value ∞. This extended distance is
called `edist`, and takes values in `ennreal`.
Many definitions and theorems expected on emetric spaces are already introduced on uniform spaces and
topological spaces. For example:
open and closed sets, compactness, completeness, continuity and uniform continuity
The class `emetric_space` therefore extends `uniform_space` (and `topological_space`).
-/
open set filter classical
noncomputable theory
open_locale uniformity topological_space big_operators filter
universes u v w
variables {α : Type u} {β : Type v} {γ : Type w}
/-- Characterizing uniformities associated to a (generalized) distance function `D`
in terms of the elements of the uniformity. -/
theorem uniformity_dist_of_mem_uniformity [linear_order β] {U : filter (α × α)} (z : β) (D : α → α → β)
(H : ∀ s, s ∈ U ↔ ∃ε>z, ∀{a b:α}, D a b < ε → (a, b) ∈ s) :
U = ⨅ ε>z, 𝓟 {p:α×α | D p.1 p.2 < ε} :=
le_antisymm
(le_infi $ λ ε, le_infi $ λ ε0, le_principal_iff.2 $ (H _).2 ⟨ε, ε0, λ a b, id⟩)
(λ r ur, let ⟨ε, ε0, h⟩ := (H _).1 ur in
mem_infi_sets ε $ mem_infi_sets ε0 $ mem_principal_sets.2 $ λ ⟨a, b⟩, h)
class has_edist (α : Type*) := (edist : α → α → ennreal)
export has_edist (edist)
/-- Creating a uniform space from an extended distance. -/
def uniform_space_of_edist
(edist : α → α → ennreal)
(edist_self : ∀ x : α, edist x x = 0)
(edist_comm : ∀ x y : α, edist x y = edist y x)
(edist_triangle : ∀ x y z : α, edist x z ≤ edist x y + edist y z) : uniform_space α :=
uniform_space.of_core {
uniformity := (⨅ ε>0, 𝓟 {p:α×α | edist p.1 p.2 < ε}),
refl := le_infi $ assume ε, le_infi $
by simp [set.subset_def, id_rel, edist_self, (>)] {contextual := tt},
comp :=
le_infi $ assume ε, le_infi $ assume h,
have (2 : ennreal) = (2 : ℕ) := by simp,
have A : 0 < ε / 2 := ennreal.div_pos_iff.2
⟨ne_of_gt h, by { convert ennreal.nat_ne_top 2 }⟩,
lift'_le
(mem_infi_sets (ε / 2) $ mem_infi_sets A (subset.refl _)) $
have ∀ (a b c : α), edist a c < ε / 2 → edist c b < ε / 2 → edist a b < ε,
from assume a b c hac hcb,
calc edist a b ≤ edist a c + edist c b : edist_triangle _ _ _
... < ε / 2 + ε / 2 : ennreal.add_lt_add hac hcb
... = ε : by rw [ennreal.add_halves],
by simpa [comp_rel],
symm := tendsto_infi.2 $ assume ε, tendsto_infi.2 $ assume h,
tendsto_infi' ε $ tendsto_infi' h $ tendsto_principal_principal.2 $ by simp [edist_comm] }
section prio
set_option default_priority 100 -- see Note [default priority]
-- the uniform structure is embedded in the emetric space structure
-- to avoid instance diamond issues. See Note [forgetful inheritance].
/-- Extended metric spaces, with an extended distance `edist` possibly taking the
value ∞
Each emetric space induces a canonical `uniform_space` and hence a canonical `topological_space`.
This is enforced in the type class definition, by extending the `uniform_space` structure. When
instantiating an `emetric_space` structure, the uniformity fields are not necessary, they will be
filled in by default. There is a default value for the uniformity, that can be substituted
in cases of interest, for instance when instantiating an `emetric_space` structure
on a product.
Continuity of `edist` is proved in `topology.instances.ennreal`
-/
class emetric_space (α : Type u) extends has_edist α : Type u :=
(edist_self : ∀ x : α, edist x x = 0)
(eq_of_edist_eq_zero : ∀ {x y : α}, edist x y = 0 → x = y)
(edist_comm : ∀ x y : α, edist x y = edist y x)
(edist_triangle : ∀ x y z : α, edist x z ≤ edist x y + edist y z)
(to_uniform_space : uniform_space α := uniform_space_of_edist edist edist_self edist_comm edist_triangle)
(uniformity_edist : 𝓤 α = ⨅ ε>0, 𝓟 {p:α×α | edist p.1 p.2 < ε} . control_laws_tac)
end prio
/- emetric spaces are less common than metric spaces. Therefore, we work in a dedicated
namespace, while notions associated to metric spaces are mostly in the root namespace. -/
variables [emetric_space α]
@[priority 100] -- see Note [lower instance priority]
instance emetric_space.to_uniform_space' : uniform_space α :=
emetric_space.to_uniform_space
export emetric_space (edist_self eq_of_edist_eq_zero edist_comm edist_triangle)
attribute [simp] edist_self
/-- Characterize the equality of points by the vanishing of their extended distance -/
@[simp] theorem edist_eq_zero {x y : α} : edist x y = 0 ↔ x = y :=
iff.intro eq_of_edist_eq_zero (assume : x = y, this ▸ edist_self _)
@[simp] theorem zero_eq_edist {x y : α} : 0 = edist x y ↔ x = y :=
iff.intro (assume h, eq_of_edist_eq_zero (h.symm))
(assume : x = y, this ▸ (edist_self _).symm)
theorem edist_le_zero {x y : α} : (edist x y ≤ 0) ↔ x = y :=
le_zero_iff_eq.trans edist_eq_zero
/-- Triangle inequality for the extended distance -/
theorem edist_triangle_left (x y z : α) : edist x y ≤ edist z x + edist z y :=
by rw edist_comm z; apply edist_triangle
theorem edist_triangle_right (x y z : α) : edist x y ≤ edist x z + edist y z :=
by rw edist_comm y; apply edist_triangle
lemma edist_triangle4 (x y z t : α) :
edist x t ≤ edist x y + edist y z + edist z t :=
calc
edist x t ≤ edist x z + edist z t : edist_triangle x z t
... ≤ (edist x y + edist y z) + edist z t : add_le_add_right (edist_triangle x y z) _
/-- The triangle (polygon) inequality for sequences of points; `finset.Ico` version. -/
lemma edist_le_Ico_sum_edist (f : ℕ → α) {m n} (h : m ≤ n) :
edist (f m) (f n) ≤ ∑ i in finset.Ico m n, edist (f i) (f (i + 1)) :=
begin
revert n,
refine nat.le_induction _ _,
{ simp only [finset.sum_empty, finset.Ico.self_eq_empty, edist_self],
-- TODO: Why doesn't Lean close this goal automatically? `apply le_refl` fails too.
exact le_refl (0:ennreal) },
{ assume n hn hrec,
calc edist (f m) (f (n+1)) ≤ edist (f m) (f n) + edist (f n) (f (n+1)) : edist_triangle _ _ _
... ≤ ∑ i in finset.Ico m n, _ + _ : add_le_add hrec (le_refl _)
... = ∑ i in finset.Ico m (n+1), _ :
by rw [finset.Ico.succ_top hn, finset.sum_insert, add_comm]; simp }
end
/-- The triangle (polygon) inequality for sequences of points; `finset.range` version. -/
lemma edist_le_range_sum_edist (f : ℕ → α) (n : ℕ) :
edist (f 0) (f n) ≤ ∑ i in finset.range n, edist (f i) (f (i + 1)) :=
finset.Ico.zero_bot n ▸ edist_le_Ico_sum_edist f (nat.zero_le n)
/-- A version of `edist_le_Ico_sum_edist` with each intermediate distance replaced
with an upper estimate. -/
lemma edist_le_Ico_sum_of_edist_le {f : ℕ → α} {m n} (hmn : m ≤ n)
{d : ℕ → ennreal} (hd : ∀ {k}, m ≤ k → k < n → edist (f k) (f (k + 1)) ≤ d k) :
edist (f m) (f n) ≤ ∑ i in finset.Ico m n, d i :=
le_trans (edist_le_Ico_sum_edist f hmn) $
finset.sum_le_sum $ λ k hk, hd (finset.Ico.mem.1 hk).1 (finset.Ico.mem.1 hk).2
/-- A version of `edist_le_range_sum_edist` with each intermediate distance replaced
with an upper estimate. -/
lemma edist_le_range_sum_of_edist_le {f : ℕ → α} (n : ℕ)
{d : ℕ → ennreal} (hd : ∀ {k}, k < n → edist (f k) (f (k + 1)) ≤ d k) :
edist (f 0) (f n) ≤ ∑ i in finset.range n, d i :=
finset.Ico.zero_bot n ▸ edist_le_Ico_sum_of_edist_le (zero_le n) (λ _ _, hd)
/-- Two points coincide if their distance is `< ε` for all positive ε -/
theorem eq_of_forall_edist_le {x y : α} (h : ∀ε > 0, edist x y ≤ ε) : x = y :=
eq_of_edist_eq_zero (eq_of_le_of_forall_le_of_dense bot_le h)
/-- Reformulation of the uniform structure in terms of the extended distance -/
theorem uniformity_edist :
𝓤 α = ⨅ ε>0, 𝓟 {p:α×α | edist p.1 p.2 < ε} :=
emetric_space.uniformity_edist
theorem uniformity_basis_edist :
(𝓤 α).has_basis (λ ε : ennreal, 0 < ε) (λ ε, {p:α×α | edist p.1 p.2 < ε}) :=
(@uniformity_edist α _).symm ▸ has_basis_binfi_principal
(λ r hr p hp, ⟨min r p, lt_min hr hp,
λ x hx, lt_of_lt_of_le hx (min_le_left _ _),
λ x hx, lt_of_lt_of_le hx (min_le_right _ _)⟩)
⟨1, ennreal.zero_lt_one⟩
/-- Characterization of the elements of the uniformity in terms of the extended distance -/
theorem mem_uniformity_edist {s : set (α×α)} :
s ∈ 𝓤 α ↔ (∃ε>0, ∀{a b:α}, edist a b < ε → (a, b) ∈ s) :=
uniformity_basis_edist.mem_uniformity_iff
/-- Given `f : β → ennreal`, if `f` sends `{i | p i}` to a set of positive numbers
accumulating to zero, then `f i`-neighborhoods of the diagonal form a basis of `𝓤 α`.
For specific bases see `uniformity_basis_edist`, `uniformity_basis_edist'`,
`uniformity_basis_edist_nnreal`, and `uniformity_basis_edist_inv_nat`. -/
protected theorem emetric.mk_uniformity_basis {β : Type*} {p : β → Prop} {f : β → ennreal}
(hf₀ : ∀ x, p x → 0 < f x) (hf : ∀ ε, 0 < ε → ∃ x (hx : p x), f x ≤ ε) :
(𝓤 α).has_basis p (λ x, {p:α×α | edist p.1 p.2 < f x}) :=
begin
refine ⟨λ s, uniformity_basis_edist.mem_iff.trans _⟩,
split,
{ rintros ⟨ε, ε₀, hε⟩,
rcases hf ε ε₀ with ⟨i, hi, H⟩,
exact ⟨i, hi, λ x hx, hε $ lt_of_lt_of_le hx H⟩ },
{ exact λ ⟨i, hi, H⟩, ⟨f i, hf₀ i hi, H⟩ }
end
/-- Given `f : β → ennreal`, if `f` sends `{i | p i}` to a set of positive numbers
accumulating to zero, then closed `f i`-neighborhoods of the diagonal form a basis of `𝓤 α`.
For specific bases see `uniformity_basis_edist_le` and `uniformity_basis_edist_le'`. -/
protected theorem emetric.mk_uniformity_basis_le {β : Type*} {p : β → Prop} {f : β → ennreal}
(hf₀ : ∀ x, p x → 0 < f x) (hf : ∀ ε, 0 < ε → ∃ x (hx : p x), f x ≤ ε) :
(𝓤 α).has_basis p (λ x, {p:α×α | edist p.1 p.2 ≤ f x}) :=
begin
refine ⟨λ s, uniformity_basis_edist.mem_iff.trans _⟩,
split,
{ rintros ⟨ε, ε₀, hε⟩,
rcases dense ε₀ with ⟨ε', hε'⟩,
rcases hf ε' hε'.1 with ⟨i, hi, H⟩,
exact ⟨i, hi, λ x hx, hε $ lt_of_le_of_lt (le_trans hx H) hε'.2⟩ },
{ exact λ ⟨i, hi, H⟩, ⟨f i, hf₀ i hi, λ x hx, H (le_of_lt hx)⟩ }
end
theorem uniformity_basis_edist_le :
(𝓤 α).has_basis (λ ε : ennreal, 0 < ε) (λ ε, {p:α×α | edist p.1 p.2 ≤ ε}) :=
emetric.mk_uniformity_basis_le (λ _, id) (λ ε ε₀, ⟨ε, ε₀, le_refl ε⟩)
theorem uniformity_basis_edist' (ε' : ennreal) (hε' : 0 < ε') :
(𝓤 α).has_basis (λ ε : ennreal, ε ∈ Ioo 0 ε') (λ ε, {p:α×α | edist p.1 p.2 < ε}) :=
emetric.mk_uniformity_basis (λ _, and.left)
(λ ε ε₀, let ⟨δ, hδ⟩ := dense hε' in
⟨min ε δ, ⟨lt_min ε₀ hδ.1, lt_of_le_of_lt (min_le_right _ _) hδ.2⟩, min_le_left _ _⟩)
theorem uniformity_basis_edist_le' (ε' : ennreal) (hε' : 0 < ε') :
(𝓤 α).has_basis (λ ε : ennreal, ε ∈ Ioo 0 ε') (λ ε, {p:α×α | edist p.1 p.2 ≤ ε}) :=
emetric.mk_uniformity_basis_le (λ _, and.left)
(λ ε ε₀, let ⟨δ, hδ⟩ := dense hε' in
⟨min ε δ, ⟨lt_min ε₀ hδ.1, lt_of_le_of_lt (min_le_right _ _) hδ.2⟩, min_le_left _ _⟩)
theorem uniformity_basis_edist_nnreal :
(𝓤 α).has_basis (λ ε : nnreal, 0 < ε) (λ ε, {p:α×α | edist p.1 p.2 < ε}) :=
emetric.mk_uniformity_basis (λ _, ennreal.coe_pos.2)
(λ ε ε₀, let ⟨δ, hδ⟩ := ennreal.lt_iff_exists_nnreal_btwn.1 ε₀ in
⟨δ, ennreal.coe_pos.1 hδ.1, le_of_lt hδ.2⟩)
theorem uniformity_basis_edist_inv_nat :
(𝓤 α).has_basis (λ _, true) (λ n:ℕ, {p:α×α | edist p.1 p.2 < (↑n)⁻¹}) :=
emetric.mk_uniformity_basis
(λ n _, ennreal.inv_pos.2 $ ennreal.nat_ne_top n)
(λ ε ε₀, let ⟨n, hn⟩ := ennreal.exists_inv_nat_lt (ne_of_gt ε₀) in ⟨n, trivial, le_of_lt hn⟩)
/-- Fixed size neighborhoods of the diagonal belong to the uniform structure -/
theorem edist_mem_uniformity {ε:ennreal} (ε0 : 0 < ε) :
{p:α×α | edist p.1 p.2 < ε} ∈ 𝓤 α :=
mem_uniformity_edist.2 ⟨ε, ε0, λ a b, id⟩
namespace emetric
theorem uniformity_has_countable_basis : is_countably_generated (𝓤 α) :=
is_countably_generated_of_seq ⟨_, uniformity_basis_edist_inv_nat.eq_infi⟩
/-- ε-δ characterization of uniform continuity on emetric spaces -/
theorem uniform_continuous_iff [emetric_space β] {f : α → β} :
uniform_continuous f ↔ ∀ ε > 0, ∃ δ > 0,
∀{a b:α}, edist a b < δ → edist (f a) (f b) < ε :=
uniformity_basis_edist.uniform_continuous_iff uniformity_basis_edist
/-- ε-δ characterization of uniform embeddings on emetric spaces -/
theorem uniform_embedding_iff [emetric_space β] {f : α → β} :
uniform_embedding f ↔ function.injective f ∧ uniform_continuous f ∧
∀ δ > 0, ∃ ε > 0, ∀ {a b : α}, edist (f a) (f b) < ε → edist a b < δ :=
uniform_embedding_def'.trans $ and_congr iff.rfl $ and_congr iff.rfl
⟨λ H δ δ0, let ⟨t, tu, ht⟩ := H _ (edist_mem_uniformity δ0),
⟨ε, ε0, hε⟩ := mem_uniformity_edist.1 tu in
⟨ε, ε0, λ a b h, ht _ _ (hε h)⟩,
λ H s su, let ⟨δ, δ0, hδ⟩ := mem_uniformity_edist.1 su, ⟨ε, ε0, hε⟩ := H _ δ0 in
⟨_, edist_mem_uniformity ε0, λ a b h, hδ (hε h)⟩⟩
/-- A map between emetric spaces is a uniform embedding if and only if the edistance between `f x`
and `f y` is controlled in terms of the distance between `x` and `y` and conversely. -/
theorem uniform_embedding_iff' [emetric_space β] {f : α → β} :
uniform_embedding f ↔
(∀ ε > 0, ∃ δ > 0, ∀ {a b : α}, edist a b < δ → edist (f a) (f b) < ε) ∧
(∀ δ > 0, ∃ ε > 0, ∀ {a b : α}, edist (f a) (f b) < ε → edist a b < δ) :=
begin
split,
{ assume h,
exact ⟨uniform_continuous_iff.1 (uniform_embedding_iff.1 h).2.1,
(uniform_embedding_iff.1 h).2.2⟩ },
{ rintros ⟨h₁, h₂⟩,
refine uniform_embedding_iff.2 ⟨_, uniform_continuous_iff.2 h₁, h₂⟩,
assume x y hxy,
have : edist x y ≤ 0,
{ refine le_of_forall_lt' (λδ δpos, _),
rcases h₂ δ δpos with ⟨ε, εpos, hε⟩,
have : edist (f x) (f y) < ε, by simpa [hxy],
exact hε this },
simpa using this }
end
/-- ε-δ characterization of Cauchy sequences on emetric spaces -/
protected lemma cauchy_iff {f : filter α} :
cauchy f ↔ f ≠ ⊥ ∧ ∀ ε > 0, ∃ t ∈ f, ∀ x y ∈ t, edist x y < ε :=
uniformity_basis_edist.cauchy_iff
/-- A very useful criterion to show that a space is complete is to show that all sequences
which satisfy a bound of the form `edist (u n) (u m) < B N` for all `n m ≥ N` are
converging. This is often applied for `B N = 2^{-N}`, i.e., with a very fast convergence to
`0`, which makes it possible to use arguments of converging series, while this is impossible
to do in general for arbitrary Cauchy sequences. -/
theorem complete_of_convergent_controlled_sequences (B : ℕ → ennreal) (hB : ∀n, 0 < B n)
(H : ∀u : ℕ → α, (∀N n m : ℕ, N ≤ n → N ≤ m → edist (u n) (u m) < B N) → ∃x, tendsto u at_top (𝓝 x)) :
complete_space α :=
uniform_space.complete_of_convergent_controlled_sequences
uniformity_has_countable_basis
(λ n, {p:α×α | edist p.1 p.2 < B n}) (λ n, edist_mem_uniformity $ hB n) H
/-- A sequentially complete emetric space is complete. -/
theorem complete_of_cauchy_seq_tendsto :
(∀ u : ℕ → α, cauchy_seq u → ∃a, tendsto u at_top (𝓝 a)) → complete_space α :=
uniform_space.complete_of_cauchy_seq_tendsto uniformity_has_countable_basis
/-- Expressing locally uniform convergence on a set using `edist`. -/
lemma tendsto_locally_uniformly_on_iff {ι : Type*} [topological_space β]
{F : ι → β → α} {f : β → α} {p : filter ι} {s : set β} :
tendsto_locally_uniformly_on F f p s ↔
∀ ε > 0, ∀ x ∈ s, ∃ t ∈ 𝓝[s] x, ∀ᶠ n in p, ∀ y ∈ t, edist (f y) (F n y) < ε :=
begin
refine ⟨λ H ε hε, H _ (edist_mem_uniformity hε), λ H u hu x hx, _⟩,
rcases mem_uniformity_edist.1 hu with ⟨ε, εpos, hε⟩,
rcases H ε εpos x hx with ⟨t, ht, Ht⟩,
exact ⟨t, ht, Ht.mono (λ n hs x hx, hε (hs x hx))⟩
end
/-- Expressing uniform convergence on a set using `edist`. -/
lemma tendsto_uniformly_on_iff {ι : Type*}
{F : ι → β → α} {f : β → α} {p : filter ι} {s : set β} :
tendsto_uniformly_on F f p s ↔ ∀ ε > 0, ∀ᶠ n in p, ∀ x ∈ s, edist (f x) (F n x) < ε :=
begin
refine ⟨λ H ε hε, H _ (edist_mem_uniformity hε), λ H u hu, _⟩,
rcases mem_uniformity_edist.1 hu with ⟨ε, εpos, hε⟩,
exact (H ε εpos).mono (λ n hs x hx, hε (hs x hx))
end
/-- Expressing locally uniform convergence using `edist`. -/
lemma tendsto_locally_uniformly_iff {ι : Type*} [topological_space β]
{F : ι → β → α} {f : β → α} {p : filter ι} :
tendsto_locally_uniformly F f p ↔
∀ ε > 0, ∀ (x : β), ∃ t ∈ 𝓝 x, ∀ᶠ n in p, ∀ y ∈ t, edist (f y) (F n y) < ε :=
by simp only [← tendsto_locally_uniformly_on_univ, tendsto_locally_uniformly_on_iff,
mem_univ, forall_const, exists_prop, nhds_within_univ]
/-- Expressing uniform convergence using `edist`. -/
lemma tendsto_uniformly_iff {ι : Type*}
{F : ι → β → α} {f : β → α} {p : filter ι} :
tendsto_uniformly F f p ↔ ∀ ε > 0, ∀ᶠ n in p, ∀ x, edist (f x) (F n x) < ε :=
by simp only [← tendsto_uniformly_on_univ, tendsto_uniformly_on_iff, mem_univ, forall_const]
end emetric
open emetric
/-- An emetric space is separated -/
@[priority 100] -- see Note [lower instance priority]
instance to_separated : separated_space α :=
separated_def.2 $ λ x y h, eq_of_forall_edist_le $
λ ε ε0, le_of_lt (h _ (edist_mem_uniformity ε0))
/-- Auxiliary function to replace the uniformity on an emetric space with
a uniformity which is equal to the original one, but maybe not defeq.
This is useful if one wants to construct an emetric space with a
specified uniformity. See Note [forgetful inheritance] explaining why having definitionally
the right uniformity is often important.
-/
def emetric_space.replace_uniformity {α} [U : uniform_space α] (m : emetric_space α)
(H : @uniformity _ U = @uniformity _ emetric_space.to_uniform_space) :
emetric_space α :=
{ edist := @edist _ m.to_has_edist,
edist_self := edist_self,
eq_of_edist_eq_zero := @eq_of_edist_eq_zero _ _,
edist_comm := edist_comm,
edist_triangle := edist_triangle,
to_uniform_space := U,
uniformity_edist := H.trans (@emetric_space.uniformity_edist α _) }
/-- The extended metric induced by an injective function taking values in an emetric space. -/
def emetric_space.induced {α β} (f : α → β) (hf : function.injective f)
(m : emetric_space β) : emetric_space α :=
{ edist := λ x y, edist (f x) (f y),
edist_self := λ x, edist_self _,
eq_of_edist_eq_zero := λ x y h, hf (edist_eq_zero.1 h),
edist_comm := λ x y, edist_comm _ _,
edist_triangle := λ x y z, edist_triangle _ _ _,
to_uniform_space := uniform_space.comap f m.to_uniform_space,
uniformity_edist := begin
apply @uniformity_dist_of_mem_uniformity _ _ _ _ _ (λ x y, edist (f x) (f y)),
refine λ s, mem_comap_sets.trans _,
split; intro H,
{ rcases H with ⟨r, ru, rs⟩,
rcases mem_uniformity_edist.1 ru with ⟨ε, ε0, hε⟩,
refine ⟨ε, ε0, λ a b h, rs (hε _)⟩, exact h },
{ rcases H with ⟨ε, ε0, hε⟩,
exact ⟨_, edist_mem_uniformity ε0, λ ⟨a, b⟩, hε⟩ }
end }
/-- Emetric space instance on subsets of emetric spaces -/
instance {α : Type*} {p : α → Prop} [t : emetric_space α] : emetric_space (subtype p) :=
t.induced coe (λ x y, subtype.ext_iff_val.2)
/-- The extended distance on a subset of an emetric space is the restriction of
the original distance, by definition -/
theorem subtype.edist_eq {p : α → Prop} (x y : subtype p) : edist x y = edist (x : α) y := rfl
/-- The product of two emetric spaces, with the max distance, is an extended
metric spaces. We make sure that the uniform structure thus constructed is the one
corresponding to the product of uniform spaces, to avoid diamond problems. -/
instance prod.emetric_space_max [emetric_space β] : emetric_space (α × β) :=
{ edist := λ x y, max (edist x.1 y.1) (edist x.2 y.2),
edist_self := λ x, by simp,
eq_of_edist_eq_zero := λ x y h, begin
cases max_le_iff.1 (le_of_eq h) with h₁ h₂,
have A : x.fst = y.fst := edist_le_zero.1 h₁,
have B : x.snd = y.snd := edist_le_zero.1 h₂,
exact prod.ext_iff.2 ⟨A, B⟩
end,
edist_comm := λ x y, by simp [edist_comm],
edist_triangle := λ x y z, max_le
(le_trans (edist_triangle _ _ _) (add_le_add (le_max_left _ _) (le_max_left _ _)))
(le_trans (edist_triangle _ _ _) (add_le_add (le_max_right _ _) (le_max_right _ _))),
uniformity_edist := begin
refine uniformity_prod.trans _,
simp [emetric_space.uniformity_edist, comap_infi],
rw ← infi_inf_eq, congr, funext,
rw ← infi_inf_eq, congr, funext,
simp [inf_principal, ext_iff, max_lt_iff]
end,
to_uniform_space := prod.uniform_space }
lemma prod.edist_eq [emetric_space β] (x y : α × β) :
edist x y = max (edist x.1 y.1) (edist x.2 y.2) :=
rfl
section pi
open finset
variables {π : β → Type*} [fintype β]
/-- The product of a finite number of emetric spaces, with the max distance, is still
an emetric space.
This construction would also work for infinite products, but it would not give rise
to the product topology. Hence, we only formalize it in the good situation of finitely many
spaces. -/
instance emetric_space_pi [∀b, emetric_space (π b)] : emetric_space (Πb, π b) :=
{ edist := λ f g, finset.sup univ (λb, edist (f b) (g b)),
edist_self := assume f, bot_unique $ finset.sup_le $ by simp,
edist_comm := assume f g, by unfold edist; congr; funext a; exact edist_comm _ _,
edist_triangle := assume f g h,
begin
simp only [finset.sup_le_iff],
assume b hb,
exact le_trans (edist_triangle _ (g b) _) (add_le_add (le_sup hb) (le_sup hb))
end,
eq_of_edist_eq_zero := assume f g eq0,
begin
have eq1 : sup univ (λ (b : β), edist (f b) (g b)) ≤ 0 := le_of_eq eq0,
simp only [finset.sup_le_iff] at eq1,
exact (funext $ assume b, edist_le_zero.1 $ eq1 b $ mem_univ b),
end,
to_uniform_space := Pi.uniform_space _,
uniformity_edist := begin
simp only [Pi.uniformity, emetric_space.uniformity_edist, comap_infi, gt_iff_lt,
preimage_set_of_eq, comap_principal],
rw infi_comm, congr, funext ε,
rw infi_comm, congr, funext εpos,
change 0 < ε at εpos,
simp [set.ext_iff, εpos]
end }
end pi
namespace emetric
variables {x y z : α} {ε ε₁ ε₂ : ennreal} {s : set α}
/-- `emetric.ball x ε` is the set of all points `y` with `edist y x < ε` -/
def ball (x : α) (ε : ennreal) : set α := {y | edist y x < ε}
@[simp] theorem mem_ball : y ∈ ball x ε ↔ edist y x < ε := iff.rfl
theorem mem_ball' : y ∈ ball x ε ↔ edist x y < ε := by rw edist_comm; refl
/-- `emetric.closed_ball x ε` is the set of all points `y` with `edist y x ≤ ε` -/
def closed_ball (x : α) (ε : ennreal) := {y | edist y x ≤ ε}
@[simp] theorem mem_closed_ball : y ∈ closed_ball x ε ↔ edist y x ≤ ε := iff.rfl
theorem ball_subset_closed_ball : ball x ε ⊆ closed_ball x ε :=
assume y, by simp; intros h; apply le_of_lt h
theorem pos_of_mem_ball (hy : y ∈ ball x ε) : 0 < ε :=
lt_of_le_of_lt (zero_le _) hy
theorem mem_ball_self (h : 0 < ε) : x ∈ ball x ε :=
show edist x x < ε, by rw edist_self; assumption
theorem mem_closed_ball_self : x ∈ closed_ball x ε :=
show edist x x ≤ ε, by rw edist_self; exact bot_le
theorem mem_ball_comm : x ∈ ball y ε ↔ y ∈ ball x ε :=
by simp [edist_comm]
theorem ball_subset_ball (h : ε₁ ≤ ε₂) : ball x ε₁ ⊆ ball x ε₂ :=
λ y (yx : _ < ε₁), lt_of_lt_of_le yx h
theorem closed_ball_subset_closed_ball (h : ε₁ ≤ ε₂) :
closed_ball x ε₁ ⊆ closed_ball x ε₂ :=
λ y (yx : _ ≤ ε₁), le_trans yx h
theorem ball_disjoint (h : ε₁ + ε₂ ≤ edist x y) : ball x ε₁ ∩ ball y ε₂ = ∅ :=
eq_empty_iff_forall_not_mem.2 $ λ z ⟨h₁, h₂⟩,
not_lt_of_le (edist_triangle_left x y z)
(lt_of_lt_of_le (ennreal.add_lt_add h₁ h₂) h)
theorem ball_subset (h : edist x y + ε₁ ≤ ε₂) (h' : edist x y < ⊤) : ball x ε₁ ⊆ ball y ε₂ :=
λ z zx, calc
edist z y ≤ edist z x + edist x y : edist_triangle _ _ _
... = edist x y + edist z x : add_comm _ _
... < edist x y + ε₁ : (ennreal.add_lt_add_iff_left h').2 zx
... ≤ ε₂ : h
theorem exists_ball_subset_ball (h : y ∈ ball x ε) : ∃ ε' > 0, ball y ε' ⊆ ball x ε :=
begin
have : 0 < ε - edist y x := by simpa using h,
refine ⟨ε - edist y x, this, ball_subset _ _⟩,
{ rw ennreal.add_sub_cancel_of_le (le_of_lt h), apply le_refl _},
{ have : edist y x ≠ ⊤ := ne_top_of_lt h, apply lt_top_iff_ne_top.2 this }
end
theorem ball_eq_empty_iff : ball x ε = ∅ ↔ ε = 0 :=
eq_empty_iff_forall_not_mem.trans
⟨λh, le_bot_iff.1 (le_of_not_gt (λ ε0, h _ (mem_ball_self ε0))),
λε0 y h, not_lt_of_le (le_of_eq ε0) (pos_of_mem_ball h)⟩
/-- Relation “two points are at a finite edistance” is an equivalence relation. -/
def edist_lt_top_setoid : setoid α :=
{ r := λ x y, edist x y < ⊤,
iseqv := ⟨λ x, by { rw edist_self, exact ennreal.coe_lt_top },
λ x y h, by rwa edist_comm,
λ x y z hxy hyz, lt_of_le_of_lt (edist_triangle x y z) (ennreal.add_lt_top.2 ⟨hxy, hyz⟩)⟩ }
@[simp] lemma ball_zero : ball x 0 = ∅ :=
by rw [emetric.ball_eq_empty_iff]
theorem nhds_basis_eball : (𝓝 x).has_basis (λ ε:ennreal, 0 < ε) (ball x) :=
nhds_basis_uniformity uniformity_basis_edist
theorem nhds_basis_closed_eball : (𝓝 x).has_basis (λ ε:ennreal, 0 < ε) (closed_ball x) :=
nhds_basis_uniformity uniformity_basis_edist_le
theorem nhds_eq : 𝓝 x = (⨅ε>0, 𝓟 (ball x ε)) :=
nhds_basis_eball.eq_binfi
theorem mem_nhds_iff : s ∈ 𝓝 x ↔ ∃ε>0, ball x ε ⊆ s := nhds_basis_eball.mem_iff
theorem is_open_iff : is_open s ↔ ∀x∈s, ∃ε>0, ball x ε ⊆ s :=
by simp [is_open_iff_nhds, mem_nhds_iff]
theorem is_open_ball : is_open (ball x ε) :=
is_open_iff.2 $ λ y, exists_ball_subset_ball
theorem is_closed_ball_top : is_closed (ball x ⊤) :=
is_open_iff.2 $ λ y hy, ⟨⊤, ennreal.coe_lt_top, subset_compl_iff_disjoint.2 $
ball_disjoint $ by { rw ennreal.top_add, exact le_of_not_lt hy }⟩
theorem ball_mem_nhds (x : α) {ε : ennreal} (ε0 : 0 < ε) : ball x ε ∈ 𝓝 x :=
mem_nhds_sets is_open_ball (mem_ball_self ε0)
/-- ε-characterization of the closure in emetric spaces -/
theorem mem_closure_iff :
x ∈ closure s ↔ ∀ε>0, ∃y ∈ s, edist x y < ε :=
(mem_closure_iff_nhds_basis nhds_basis_eball).trans $
by simp only [mem_ball, edist_comm x]
theorem tendsto_nhds {f : filter β} {u : β → α} {a : α} :
tendsto u f (𝓝 a) ↔ ∀ ε > 0, ∀ᶠ x in f, edist (u x) a < ε :=
nhds_basis_eball.tendsto_right_iff
theorem tendsto_at_top [nonempty β] [semilattice_sup β] (u : β → α) {a : α} :
tendsto u at_top (𝓝 a) ↔ ∀ε>0, ∃N, ∀n≥N, edist (u n) a < ε :=
(at_top_basis.tendsto_iff nhds_basis_eball).trans $
by simp only [exists_prop, true_and, mem_Ici, mem_ball]
/-- In an emetric space, Cauchy sequences are characterized by the fact that, eventually,
the edistance between its elements is arbitrarily small -/
@[nolint ge_or_gt] -- see Note [nolint_ge]
theorem cauchy_seq_iff [nonempty β] [semilattice_sup β] {u : β → α} :
cauchy_seq u ↔ ∀ε>0, ∃N, ∀m n≥N, edist (u m) (u n) < ε :=
uniformity_basis_edist.cauchy_seq_iff
/-- A variation around the emetric characterization of Cauchy sequences -/
theorem cauchy_seq_iff' [nonempty β] [semilattice_sup β] {u : β → α} :
cauchy_seq u ↔ ∀ε>(0 : ennreal), ∃N, ∀n≥N, edist (u n) (u N) < ε :=
uniformity_basis_edist.cauchy_seq_iff'
/-- A variation of the emetric characterization of Cauchy sequences that deals with
`nnreal` upper bounds. -/
theorem cauchy_seq_iff_nnreal [nonempty β] [semilattice_sup β] {u : β → α} :
cauchy_seq u ↔ ∀ ε : nnreal, 0 < ε → ∃ N, ∀ n, N ≤ n → edist (u n) (u N) < ε :=
uniformity_basis_edist_nnreal.cauchy_seq_iff'
theorem totally_bounded_iff {s : set α} :
totally_bounded s ↔ ∀ ε > 0, ∃t : set α, finite t ∧ s ⊆ ⋃y∈t, ball y ε :=
⟨λ H ε ε0, H _ (edist_mem_uniformity ε0),
λ H r ru, let ⟨ε, ε0, hε⟩ := mem_uniformity_edist.1 ru,
⟨t, ft, h⟩ := H ε ε0 in
⟨t, ft, subset.trans h $ Union_subset_Union $ λ y, Union_subset_Union $ λ yt z, hε⟩⟩
theorem totally_bounded_iff' {s : set α} :
totally_bounded s ↔ ∀ ε > 0, ∃t⊆s, finite t ∧ s ⊆ ⋃y∈t, ball y ε :=
⟨λ H ε ε0, (totally_bounded_iff_subset.1 H) _ (edist_mem_uniformity ε0),
λ H r ru, let ⟨ε, ε0, hε⟩ := mem_uniformity_edist.1 ru,
⟨t, _, ft, h⟩ := H ε ε0 in
⟨t, ft, subset.trans h $ Union_subset_Union $ λ y, Union_subset_Union $ λ yt z, hε⟩⟩
section compact
/-- A compact set in an emetric space is separable, i.e., it is the closure of a countable set -/
lemma countable_closure_of_compact {α : Type u} [emetric_space α] {s : set α} (hs : is_compact s) :
∃ t ⊆ s, (countable t ∧ s = closure t) :=
begin
have A : ∀ (e:ennreal), e > 0 → ∃ t ⊆ s, (finite t ∧ s ⊆ (⋃x∈t, ball x e)) :=
totally_bounded_iff'.1 (compact_iff_totally_bounded_complete.1 hs).1,
-- assume e, finite_cover_balls_of_compact hs,
have B : ∀ (e:ennreal), ∃ t ⊆ s, finite t ∧ (e > 0 → s ⊆ (⋃x∈t, ball x e)),
{ intro e,
cases le_or_gt e 0 with h,
{ exact ⟨∅, by finish⟩ },
{ rcases A e h with ⟨s, ⟨finite_s, closure_s⟩⟩, existsi s, finish }},
/-The desired countable set is obtained by taking for each `n` the centers of a finite cover
by balls of radius `1/n`, and then the union over `n`. -/
choose T T_in_s finite_T using B,
let t := ⋃n:ℕ, T n⁻¹,
have T₁ : t ⊆ s := begin apply Union_subset, assume n, apply T_in_s end,
have T₂ : countable t := by finish [countable_Union, finite.countable],
have T₃ : s ⊆ closure t,
{ intros x x_in_s,
apply mem_closure_iff.2,
intros ε εpos,
rcases ennreal.exists_inv_nat_lt (bot_lt_iff_ne_bot.1 εpos) with ⟨n, hn⟩,
have inv_n_pos : (0 : ennreal) < (n : ℕ)⁻¹ := by simp [ennreal.bot_lt_iff_ne_bot],
have C : x ∈ (⋃y∈ T (n : ℕ)⁻¹, ball y (n : ℕ)⁻¹) :=
mem_of_mem_of_subset x_in_s ((finite_T (n : ℕ)⁻¹).2 inv_n_pos),
rcases mem_Union.1 C with ⟨y, _, ⟨y_in_T, rfl⟩, Dxy⟩,
simp at Dxy, -- Dxy : edist x y < 1 / ↑n
have : y ∈ t := mem_of_mem_of_subset y_in_T (by apply subset_Union (λ (n:ℕ), T (n : ℕ)⁻¹)),
have : edist x y < ε := lt_trans Dxy hn,
exact ⟨y, ‹y ∈ t›, ‹edist x y < ε›⟩ },
have T₄ : closure t ⊆ s := calc
closure t ⊆ closure s : closure_mono T₁
... = s : hs.is_closed.closure_eq,
exact ⟨t, ⟨T₁, T₂, subset.antisymm T₃ T₄⟩⟩
end
end compact
section first_countable
@[priority 100] -- see Note [lower instance priority]
instance (α : Type u) [emetric_space α] :
topological_space.first_countable_topology α :=
uniform_space.first_countable_topology uniformity_has_countable_basis
end first_countable
section second_countable
open topological_space
/-- A separable emetric space is second countable: one obtains a countable basis by taking
the balls centered at points in a dense subset, and with rational radii. We do not register
this as an instance, as there is already an instance going in the other direction
from second countable spaces to separable spaces, and we want to avoid loops. -/
lemma second_countable_of_separable (α : Type u) [emetric_space α] [separable_space α] :
second_countable_topology α :=
let ⟨S, ⟨S_countable, S_dense⟩⟩ := separable_space.exists_countable_closure_eq_univ in
⟨⟨⋃x ∈ S, ⋃ (n : nat), {ball x (n⁻¹)},
⟨show countable ⋃x ∈ S, ⋃ (n : nat), {ball x (n⁻¹)},
{ apply S_countable.bUnion,
intros a aS,
apply countable_Union,
simp },
show uniform_space.to_topological_space = generate_from (⋃x ∈ S, ⋃ (n : nat), {ball x (n⁻¹)}),
{ have A : ∀ (u : set α), (u ∈ ⋃x ∈ S, ⋃ (n : nat), ({ball x ((n : ennreal)⁻¹)} : set (set α))) → is_open u,
{ simp only [and_imp, exists_prop, set.mem_Union, set.mem_singleton_iff, exists_imp_distrib],
intros u x hx i u_ball,
rw [u_ball],
exact is_open_ball },
have B : is_topological_basis (⋃x ∈ S, ⋃ (n : nat), ({ball x (n⁻¹)} : set (set α))),
{ refine is_topological_basis_of_open_of_nhds A (λa u au open_u, _),
rcases is_open_iff.1 open_u a au with ⟨ε, εpos, εball⟩,
have : ε / 2 > 0 := ennreal.half_pos εpos,
/- The ball `ball a ε` is included in `u`. We need to find one of our balls `ball x (n⁻¹)`
containing `a` and contained in `ball a ε`. For this, we take `n` larger than `2/ε`, and
then `x` in `S` at distance at most `n⁻¹` of `a` -/
rcases ennreal.exists_inv_nat_lt (bot_lt_iff_ne_bot.1 (ennreal.half_pos εpos)) with ⟨n, εn⟩,
have : (0 : ennreal) < n⁻¹ := by simp [ennreal.bot_lt_iff_ne_bot],
have : (a : α) ∈ closure (S : set α) := by rw [S_dense]; simp,
rcases mem_closure_iff.1 this _ ‹(0 : ennreal) < n⁻¹› with ⟨x, xS, xdist⟩,
existsi ball x (↑n)⁻¹,
have I : ball x (n⁻¹) ⊆ ball a ε := λy ydist, calc
edist y a = edist a y : edist_comm _ _
... ≤ edist a x + edist y x : edist_triangle_right _ _ _
... < n⁻¹ + n⁻¹ : ennreal.add_lt_add xdist ydist
... < ε/2 + ε/2 : ennreal.add_lt_add εn εn
... = ε : ennreal.add_halves _,
simp only [emetric.mem_ball, exists_prop, set.mem_Union, set.mem_singleton_iff],
exact ⟨⟨x, ⟨xS, ⟨n, rfl⟩⟩⟩, ⟨by simpa, subset.trans I εball⟩⟩ },
exact B.2.2 }⟩⟩⟩
end second_countable
section diam
/-- The diameter of a set in an emetric space, named `emetric.diam` -/
def diam (s : set α) := ⨆ (x ∈ s) (y ∈ s), edist x y
lemma diam_le_iff_forall_edist_le {d : ennreal} :
diam s ≤ d ↔ ∀ (x ∈ s) (y ∈ s), edist x y ≤ d :=
by simp only [diam, supr_le_iff]
/-- If two points belong to some set, their edistance is bounded by the diameter of the set -/
lemma edist_le_diam_of_mem (hx : x ∈ s) (hy : y ∈ s) : edist x y ≤ diam s :=
diam_le_iff_forall_edist_le.1 (le_refl _) x hx y hy
/-- If the distance between any two points in a set is bounded by some constant, this constant
bounds the diameter. -/
lemma diam_le_of_forall_edist_le {d : ennreal} (h : ∀ (x ∈ s) (y ∈ s), edist x y ≤ d) :
diam s ≤ d :=
diam_le_iff_forall_edist_le.2 h
/-- The diameter of a subsingleton vanishes. -/
lemma diam_subsingleton (hs : s.subsingleton) : diam s = 0 :=
le_zero_iff_eq.1 $ diam_le_of_forall_edist_le $
λ x hx y hy, (hs hx hy).symm ▸ edist_self y ▸ le_refl _
/-- The diameter of the empty set vanishes -/
@[simp] lemma diam_empty : diam (∅ : set α) = 0 :=
diam_subsingleton subsingleton_empty
/-- The diameter of a singleton vanishes -/
@[simp] lemma diam_singleton : diam ({x} : set α) = 0 :=
diam_subsingleton subsingleton_singleton
lemma diam_eq_zero_iff : diam s = 0 ↔ s.subsingleton :=
⟨λ h x hx y hy, edist_le_zero.1 $ h ▸ edist_le_diam_of_mem hx hy, diam_subsingleton⟩
lemma diam_pos_iff : 0 < diam s ↔ ∃ (x ∈ s) (y ∈ s), x ≠ y :=
begin
have := not_congr (@diam_eq_zero_iff _ _ s),
dunfold set.subsingleton at this,
push_neg at this,
simpa only [zero_lt_iff_ne_zero, exists_prop] using this
end
lemma diam_insert : diam (insert x s) = max (⨆ y ∈ s, edist x y) (diam s) :=
eq_of_forall_ge_iff $ λ d, by simp only [diam_le_iff_forall_edist_le, ball_insert_iff,
edist_self, edist_comm x, max_le_iff, supr_le_iff, zero_le, true_and,
forall_and_distrib, and_self, ← and_assoc]
lemma diam_pair : diam ({x, y} : set α) = edist x y :=
by simp only [supr_singleton, diam_insert, diam_singleton, ennreal.max_zero_right]
lemma diam_triple :
diam ({x, y, z} : set α) = max (max (edist x y) (edist x z)) (edist y z) :=
by simp only [diam_insert, supr_insert, supr_singleton, diam_singleton,
ennreal.max_zero_right, ennreal.sup_eq_max]
/-- The diameter is monotonous with respect to inclusion -/
lemma diam_mono {s t : set α} (h : s ⊆ t) : diam s ≤ diam t :=
diam_le_of_forall_edist_le $ λ x hx y hy, edist_le_diam_of_mem (h hx) (h hy)
/-- The diameter of a union is controlled by the diameter of the sets, and the edistance
between two points in the sets. -/
lemma diam_union {t : set α} (xs : x ∈ s) (yt : y ∈ t) : diam (s ∪ t) ≤ diam s + edist x y + diam t :=
begin
have A : ∀a ∈ s, ∀b ∈ t, edist a b ≤ diam s + edist x y + diam t := λa ha b hb, calc
edist a b ≤ edist a x + edist x y + edist y b : edist_triangle4 _ _ _ _
... ≤ diam s + edist x y + diam t :
add_le_add (add_le_add (edist_le_diam_of_mem ha xs) (le_refl _)) (edist_le_diam_of_mem yt hb),
refine diam_le_of_forall_edist_le (λa ha b hb, _),
cases (mem_union _ _ _).1 ha with h'a h'a; cases (mem_union _ _ _).1 hb with h'b h'b,
{ calc edist a b ≤ diam s : edist_le_diam_of_mem h'a h'b
... ≤ diam s + (edist x y + diam t) : le_add_right (le_refl _)
... = diam s + edist x y + diam t : by simp only [add_comm, eq_self_iff_true, add_left_comm] },
{ exact A a h'a b h'b },
{ have Z := A b h'b a h'a, rwa [edist_comm] at Z },
{ calc edist a b ≤ diam t : edist_le_diam_of_mem h'a h'b
... ≤ (diam s + edist x y) + diam t : le_add_left (le_refl _) }
end
lemma diam_union' {t : set α} (h : (s ∩ t).nonempty) : diam (s ∪ t) ≤ diam s + diam t :=
let ⟨x, ⟨xs, xt⟩⟩ := h in by simpa using diam_union xs xt
lemma diam_closed_ball {r : ennreal} : diam (closed_ball x r) ≤ 2 * r :=
diam_le_of_forall_edist_le $ λa ha b hb, calc
edist a b ≤ edist a x + edist b x : edist_triangle_right _ _ _
... ≤ r + r : add_le_add ha hb
... = 2 * r : by simp [mul_two, mul_comm]
lemma diam_ball {r : ennreal} : diam (ball x r) ≤ 2 * r :=
le_trans (diam_mono ball_subset_closed_ball) diam_closed_ball
end diam
end emetric --namespace
|
0e47755dd698460f92e604f6219bc2f77aea866e | de91c42b87530c3bdcc2b138ef1a3c3d9bee0d41 | /old/eval/luminousIntensityEval.lean | 60be9b72f98d69508f3e40e22aa2096cd1a05e5d | [] | no_license | kevinsullivan/lang | d3e526ba363dc1ddf5ff1c2f36607d7f891806a7 | e9d869bff94fb13ad9262222a6f3c4aafba82d5e | refs/heads/master | 1,687,840,064,795 | 1,628,047,969,000 | 1,628,047,969,000 | 282,210,749 | 0 | 1 | null | 1,608,153,830,000 | 1,595,592,637,000 | Lean | UTF-8 | Lean | false | false | 657 | lean | import ..imperative_DSL.environment
open lang.classicalLuminousIntensity
attribute [reducible]
def classicalLuminousIntensityEval : lang.classicalLuminousIntensity.spaceExpr → environment.env → classicalLuminousIntensity
| (lang.classicalLuminousIntensity.spaceExpr.lit V) i := V
| (lang.classicalLuminousIntensity.spaceExpr.var v) i := i.li.sp v
attribute [reducible]
def classicalLuminousIntensityQuantityEval : lang.classicalLuminousIntensity.QuantityExpr → environment.env → classicalLuminousIntensityQuantity
| (lang.classicalLuminousIntensity.QuantityExpr.lit V) i := V
| (lang.classicalLuminousIntensity.QuantityExpr.var v) i := i.li.s v
|
3f7a9617f9d635b97065001e1501d8e5ae3fca7d | 4fa161becb8ce7378a709f5992a594764699e268 | /src/topology/uniform_space/absolute_value.lean | 3579ef6359c17986f5b46b42edf4e4431dab6fde | [
"Apache-2.0"
] | permissive | laughinggas/mathlib | e4aa4565ae34e46e834434284cb26bd9d67bc373 | 86dcd5cda7a5017c8b3c8876c89a510a19d49aad | refs/heads/master | 1,669,496,232,688 | 1,592,831,995,000 | 1,592,831,995,000 | 274,155,979 | 0 | 0 | Apache-2.0 | 1,592,835,190,000 | 1,592,835,189,000 | null | UTF-8 | Lean | false | false | 2,972 | lean | /-
Copyright (c) 2019 Patrick Massot. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Patrick Massot
-/
import data.real.cau_seq
import topology.uniform_space.basic
/-!
# Uniform structure induced by an absolute value
We build a uniform space structure on a commutative ring `R` equipped with an absolute value into
a linear ordered field `𝕜`. Of course in the case `R` is `ℚ`, `ℝ` or `ℂ` and
`𝕜 = ℝ`, we get the same thing as the metric space construction, and the general construction
follows exactly the same path.
## Implementation details
Note that we import `data.real.cau_seq` because this is where absolute values are defined, but
the current file does not depend on real numbers. TODO: extract absolute values from that
`data.real` folder.
## References
* [N. Bourbaki, *Topologie générale*][bourbaki1966]
## Tags
absolute value, uniform spaces
-/
open set function filter uniform_space
namespace is_absolute_value
variables {𝕜 : Type*} [discrete_linear_ordered_field 𝕜]
variables {R : Type*} [comm_ring R] (abv : R → 𝕜) [is_absolute_value abv]
/-- The uniformity coming from an absolute value. -/
def uniform_space_core : uniform_space.core R :=
{ uniformity := (⨅ ε>0, principal {p:R×R | abv (p.2 - p.1) < ε}),
refl := le_infi $ assume ε, le_infi $ assume ε_pos, principal_mono.2
(λ ⟨x, y⟩ h, by simpa [show x = y, from h, abv_zero abv]),
symm := tendsto_infi.2 $ assume ε, tendsto_infi.2 $ assume h,
tendsto_infi' ε $ tendsto_infi' h $ tendsto_principal_principal.2 $ λ ⟨x, y⟩ h,
have h : abv (y - x) < ε, by simpa [-sub_eq_add_neg] using h,
by rwa abv_sub abv at h,
comp := le_infi $ assume ε, le_infi $ assume h, lift'_le
(mem_infi_sets (ε / 2) $ mem_infi_sets (div_pos_of_pos_of_pos h two_pos) (subset.refl _)) $
have ∀ (a b c : R), abv (c-a) < ε / 2 → abv (b-c) < ε / 2 → abv (b-a) < ε,
from assume a b c hac hcb,
calc abv (b - a) ≤ _ : abv_sub_le abv b c a
... = abv (c - a) + abv (b - c) : add_comm _ _
... < ε / 2 + ε / 2 : add_lt_add hac hcb
... = ε : by rw [div_add_div_same, add_self_div_two],
by simpa [comp_rel] }
/-- The uniform structure coming from an absolute value. -/
def uniform_space : uniform_space R :=
uniform_space.of_core (uniform_space_core abv)
@[nolint ge_or_gt] -- see Note [nolint_ge]
theorem mem_uniformity {s : set (R×R)} :
s ∈ (uniform_space_core abv).uniformity ↔
(∃ε>0, ∀{a b:R}, abv (b - a) < ε → (a, b) ∈ s) :=
begin
suffices : s ∈ (⨅ ε: {ε : 𝕜 // ε > 0}, principal {p:R×R | abv (p.2 - p.1) < ε.val}) ↔ _,
{ rw infi_subtype at this,
exact this },
rw mem_infi,
{ simp [subset_def] },
{ exact assume ⟨r, hr⟩ ⟨p, hp⟩, ⟨⟨min r p, lt_min hr hp⟩, by simp [lt_min_iff, (≥)] {contextual := tt}⟩, },
{ exact ⟨⟨1, zero_lt_one⟩⟩ }
end
end is_absolute_value
|
830629a65e2e4d51ab1bd72cb344f021da74293b | 0dc59d2b959c9b11a672f655b104d7d7d3e37660 | /other_peoples_work/vvs_NNG4.lean | 58e7daaa4e81e27fcecf2cf1a6fea2cd99b3685a | [] | no_license | kbuzzard/lean4-filters | 5aa17d95079ceb906622543209064151fa645e71 | 29f90055b7a2341c86d924954463c439bd128fb7 | refs/heads/master | 1,679,762,259,673 | 1,616,701,300,000 | 1,616,701,300,000 | 350,784,493 | 5 | 1 | null | 1,625,691,081,000 | 1,616,517,435,000 | Lean | UTF-8 | Lean | false | false | 1,201 | lean | theorem add_zero : x + 0 = x := by
rfl
theorem add_succ : x + Nat.succ y = Nat.succ (x + y) := by
rfl
theorem one_Eq_succ_zero : 1 = Nat.succ 0 := by
rfl
--set_option hygienicIntro false in
theorem zero_add : 0 + x = x := by
induction x with | succ _ ih => _ | _ => _
rfl
rewrite add_succ
apply congrArg -- or just `rw ih`/`rw v_0`
assumption
theorem add_assoc (a b c : Nat) : (a + b) + c = a + (b + c) := by
induction c with | succ _ ih => _ | _ => _
rewrite add_zero
rewrite add_zero
rfl
rewrite add_succ
rewrite add_succ
rewrite add_succ
rewrite ih
rfl
theorem succ_add (a b : Nat) : Nat.succ a + b = Nat.succ (a + b) := by
induction b with | succ _ ih => _ | _ => _
rfl
rewrite add_succ
rewrite add_succ
rewrite ih
rfl
theorem add_comm (a b : Nat) : a + b = b + a := by
induction b with | succ _ ih => _ | _ => _
rewrite zero_add
rfl
rewrite add_succ
rewrite succ_add
rewrite ih
rfl
theorem succ_Eq_add_one (n : Nat) : Nat.succ n = n + 1 := by
rewrite one_Eq_succ_zero
rewrite add_succ
rfl
theorem add_rightComm (a b c : Nat) : a + b + c = a + c + b := by
rewrite add_assoc
rewrite add_comm b
rewrite add_assoc
rfl
|
554f4d4d10ed268a1d80ded7c2b9a595f54e9992 | acc85b4be2c618b11fc7cb3005521ae6858a8d07 | /analysis/topology/uniform_space.lean | 0acf70915c22a20952f5121fb944add20c7b56bc | [
"Apache-2.0"
] | permissive | linpingchuan/mathlib | d49990b236574df2a45d9919ba43c923f693d341 | 5ad8020f67eb13896a41cc7691d072c9331b1f76 | refs/heads/master | 1,626,019,377,808 | 1,508,048,784,000 | 1,508,048,784,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 71,500 | lean | /-
Copyright (c) 2017 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl
Theory of uniform spaces.
Uniform spaces are a generalization of metric spaces and topological groups. Many concepts directly
generalize to uniform spaces, e.g.
* completeness
* completion (on Cauchy filters instead of Cauchy sequences)
* extension of uniform continuous functions to complete spaces
* uniform contiunuity & embedding
* totally bounded
* totally bounded ∧ complete → compact
One reason to directly formalize uniform spaces is foundational: we define ℝ as a completion of ℚ.
The central concept of uniform spaces is its uniformity: a filter relating two elemenets of the
space. This filter is reflexive, symmetric and transitive. So a set (i.e. a relation) in this filter
represents a 'distance': it is reflexive, symmetric and the uniformity contains a set for which the
`triangular` rule holds.
The formalization is mostly based on the books:
N. Bourbaki: General Topology
I. M. James: Topologies and Uniformities
A major difference is that this formalization is heavily based on the filter library.
-/
import order.filter data.quot analysis.topology.topological_space analysis.topology.continuity
open set lattice filter classical
local attribute [instance] decidable_inhabited prop_decidable
set_option eqn_compiler.zeta true
universes u
section
variables {α : Type*} {β : Type*} {γ : Type*} {δ : Type*} {ι : Sort*}
def id_rel {α : Type*} := {p : α × α | p.1 = p.2}
def comp_rel {α : Type u} (r₁ r₂ : set (α×α)) := {p : α × α | ∃z:α, (p.1, z) ∈ r₁ ∧ (z, p.2) ∈ r₂}
@[simp] theorem swap_id_rel : prod.swap '' id_rel = @id_rel α :=
set.ext $ assume ⟨a, b⟩, by simp [image_swap_eq_preimage_swap]; exact eq_comm
theorem monotone_comp_rel [preorder β] {f g : β → set (α×α)}
(hf : monotone f) (hg : monotone g) : monotone (λx, comp_rel (f x) (g x)) :=
assume a b h p ⟨z, h₁, h₂⟩, ⟨z, hf h h₁, hg h h₂⟩
lemma prod_mk_mem_comp_rel {a b c : α} {s t : set (α×α)} (h₁ : (a, c) ∈ s) (h₂ : (c, b) ∈ t) :
(a, b) ∈ comp_rel s t :=
⟨c, h₁, h₂⟩
@[simp] lemma id_comp_rel {r : set (α×α)} : comp_rel id_rel r = r :=
set.ext $ assume ⟨a, b⟩, ⟨assume ⟨a', heq, ha'⟩,
(show a' = a, from heq.symm) ▸ ha',
assume ha, ⟨a, rfl, ha⟩⟩
/-- This core description of a uniform space is outside of the type class hierarchy. It is useful
for constructions of uniform spaces, when the topology is derived from the uniform space. -/
structure uniform_space.core (α : Type u) :=
(uniformity : filter (α × α))
(refl : principal id_rel ≤ uniformity)
(symm : tendsto prod.swap uniformity uniformity)
(comp : uniformity.lift' (λs, comp_rel s s) ≤ uniformity)
def uniform_space.core.to_topological_space {α : Type u} (u : uniform_space.core α) :
topological_space α :=
{ topological_space .
is_open := λs, ∀x∈s, { p : α × α | p.1 = x → p.2 ∈ s } ∈ u.uniformity.sets,
is_open_univ := by simp; intro; exact univ_mem_sets,
is_open_inter := assume s t hs ht x ⟨xs, xt⟩,
u.uniformity.upwards_sets (inter_mem_sets (hs x xs) (ht x xt)) $ assume p ⟨ps, pt⟩ h, ⟨ps h, pt h⟩,
is_open_sUnion := assume s hs x ⟨t, ts, xt⟩,
u.uniformity.upwards_sets (hs t ts x xt) $ assume p ph h, ⟨t, ts, ph h⟩ }
lemma uniform_space.core_eq : ∀{u₁ u₂ : uniform_space.core α}, u₁.uniformity = u₂.uniformity → u₁ = u₂
| ⟨u₁, _, _, _⟩ ⟨u₂, _, _, _⟩ h := have u₁ = u₂, from h, by simp [*]
/-- uniformity: usable typeclass incorporating a topology -/
class uniform_space (α : Type u) extends topological_space α, uniform_space.core α :=
(is_open_uniformity : ∀s, is_open s ↔ (∀x∈s, { p : α × α | p.1 = x → p.2 ∈ s } ∈ uniformity.sets))
def uniform_space.of_core {α : Type u} (u : uniform_space.core α) : uniform_space α :=
{ to_core := u,
to_topological_space := u.to_topological_space,
is_open_uniformity := assume a, iff.refl _ }
def uniform_space.of_core_eq {α : Type u} (u : uniform_space.core α) (t : topological_space α)
(h : t = u.to_topological_space) : uniform_space α :=
{ to_core := u,
to_topological_space := t,
is_open_uniformity := assume a, h.symm ▸ iff.refl _ }
lemma uniform_space.to_core_to_topological_space (u : uniform_space α) :
u.to_core.to_topological_space = u.to_topological_space :=
topological_space_eq $ funext $ assume s,
by rw [uniform_space.core.to_topological_space, uniform_space.is_open_uniformity]
lemma uniform_space_eq : ∀{u₁ u₂ : uniform_space α}, u₁.uniformity = u₂.uniformity → u₁ = u₂
| ⟨t₁, u₁, o₁⟩ ⟨t₂, u₂, o₂⟩ h :=
have u₁ = u₂, from uniform_space.core_eq h,
have t₁ = t₂, from topological_space_eq $ funext $ assume s, by rw [o₁, o₂]; simp [this],
by simp [*]
lemma uniform_space.of_core_eq_to_core
(u : uniform_space α) (t : topological_space α) (h : t = u.to_core.to_topological_space) :
uniform_space.of_core_eq u.to_core t h = u :=
uniform_space_eq rfl
section uniform_space
variables [uniform_space α]
def uniformity : filter (α × α) := (@uniform_space.to_core α _).uniformity
lemma is_open_uniformity {s : set α} :
is_open s ↔ (∀x∈s, { p : α × α | p.1 = x → p.2 ∈ s } ∈ (@uniformity α _).sets) :=
uniform_space.is_open_uniformity s
lemma refl_le_uniformity : principal id_rel ≤ @uniformity α _ :=
(@uniform_space.to_core α _).refl
lemma refl_mem_uniformity {x : α} {s : set (α × α)} (h : s ∈ (@uniformity α _).sets) :
(x, x) ∈ s :=
refl_le_uniformity h rfl
lemma symm_le_uniformity : map (@prod.swap α α) uniformity ≤ uniformity :=
(@uniform_space.to_core α _).symm
lemma comp_le_uniformity : uniformity.lift' (λs:set (α×α), comp_rel s s) ≤ uniformity :=
(@uniform_space.to_core α _).comp
lemma tendsto_swap_uniformity : tendsto prod.swap (@uniformity α _) uniformity :=
symm_le_uniformity
lemma tendsto_const_uniformity {a : α} {f : filter β} : tendsto (λ_, (a, a)) f uniformity :=
assume s hs,
show {x | (a, a) ∈ s} ∈ f.sets,
from univ_mem_sets' $ assume b, refl_mem_uniformity hs
lemma comp_mem_uniformity_sets {s : set (α × α)} (hs : s ∈ (@uniformity α _).sets) :
∃t∈(@uniformity α _).sets, comp_rel t t ⊆ s :=
have s ∈ (uniformity.lift' (λt:set (α×α), comp_rel t t)).sets,
from comp_le_uniformity hs,
(mem_lift'_iff $ monotone_comp_rel monotone_id monotone_id).mp this
lemma symm_of_uniformity {s : set (α × α)} (hs : s ∈ (@uniformity α _).sets) :
∃t∈(@uniformity α _).sets, (∀a b, (a, b) ∈ t → (b, a) ∈ t) ∧ t ⊆ s :=
have preimage prod.swap s ∈ (@uniformity α _).sets, from symm_le_uniformity hs,
⟨s ∩ preimage prod.swap s, inter_mem_sets hs this, assume a b ⟨h₁, h₂⟩, ⟨h₂, h₁⟩, inter_subset_left _ _⟩
lemma comp_symm_of_uniformity {s : set (α × α)} (hs : s ∈ (@uniformity α _).sets) :
∃t∈(@uniformity α _).sets, (∀{a b}, (a, b) ∈ t → (b, a) ∈ t) ∧ comp_rel t t ⊆ s :=
let ⟨t, ht₁, ht₂⟩ := comp_mem_uniformity_sets hs in
let ⟨t', ht', ht'₁, ht'₂⟩ := symm_of_uniformity ht₁ in
⟨t', ht', ht'₁, subset.trans (monotone_comp_rel monotone_id monotone_id ht'₂) ht₂⟩
lemma uniformity_le_symm : uniformity ≤ map (@prod.swap α α) uniformity :=
calc uniformity = id <$> uniformity : (functor.id_map _).symm
... = (@prod.swap α α ∘ prod.swap) <$> uniformity :
congr_arg (λf : (α×α)→(α×α), f <$> uniformity) (by apply funext; intro x; cases x; refl)
... = (map prod.swap ∘ map prod.swap) uniformity :
congr map_compose rfl
... ≤ (@prod.swap α α) <$> uniformity : map_mono symm_le_uniformity
lemma uniformity_eq_symm : uniformity = (@prod.swap α α) <$> uniformity :=
le_antisymm uniformity_le_symm symm_le_uniformity
theorem uniformity_lift_le_swap {g : set (α×α) → filter β} {f : filter β} (hg : monotone g)
(h : uniformity.lift (λs, g (preimage prod.swap s)) ≤ f) : uniformity.lift g ≤ f :=
le_trans
(lift_mono uniformity_le_symm (le_refl _))
(by rw [map_lift_eq2 hg, image_swap_eq_preimage_swap]; exact h)
lemma uniformity_lift_le_comp {f : set (α×α) → filter β} (h : monotone f):
uniformity.lift (λs, f (comp_rel s s)) ≤ uniformity.lift f :=
calc uniformity.lift (λs, f (comp_rel s s)) =
(uniformity.lift' (λs:set (α×α), comp_rel s s)).lift f :
begin
rw [lift_lift'_assoc],
exact monotone_comp_rel monotone_id monotone_id,
exact h
end
... ≤ uniformity.lift f : lift_mono comp_le_uniformity (le_refl _)
lemma comp_le_uniformity3 :
uniformity.lift' (λs:set (α×α), comp_rel s (comp_rel s s)) ≤ uniformity :=
calc uniformity.lift' (λd, comp_rel d (comp_rel d d)) =
uniformity.lift (λs, uniformity.lift' (λt:set(α×α), comp_rel s (comp_rel t t))) :
begin
rw [lift_lift'_same_eq_lift'],
exact (assume x, monotone_comp_rel monotone_const $ monotone_comp_rel monotone_id monotone_id),
exact (assume x, monotone_comp_rel monotone_id monotone_const),
end
... ≤ uniformity.lift (λs, uniformity.lift' (λt:set(α×α), comp_rel s t)) :
lift_mono' $ assume s hs, @uniformity_lift_le_comp α _ _ (principal ∘ comp_rel s) $
monotone_comp (monotone_comp_rel monotone_const monotone_id) monotone_principal
... = uniformity.lift' (λs:set(α×α), comp_rel s s) :
lift_lift'_same_eq_lift'
(assume s, monotone_comp_rel monotone_const monotone_id)
(assume s, monotone_comp_rel monotone_id monotone_const)
... ≤ uniformity : comp_le_uniformity
lemma mem_nhds_uniformity_iff {x : α} {s : set α} :
(s ∈ (nhds x).sets) ↔ ({p : α × α | p.1 = x → p.2 ∈ s} ∈ (@uniformity α _).sets) :=
⟨ begin
simp [mem_nhds_sets_iff, is_open_uniformity],
exact assume t ts xt ht, uniformity.upwards_sets (ht x xt) $ assume ⟨x', y⟩ h eq, ts $ h eq
end,
assume hs,
mem_nhds_sets_iff.mpr ⟨{x | {p : α × α | p.1 = x → p.2 ∈ s} ∈ (@uniformity α _).sets},
assume x', assume hx' : {p : α × α | p.fst = x' → p.snd ∈ s} ∈ (@uniformity α _).sets,
refl_mem_uniformity hx' rfl,
is_open_uniformity.mpr $ assume x' hx',
let ⟨t, ht, tr⟩ := comp_mem_uniformity_sets hx' in
uniformity.upwards_sets ht $
assume ⟨a, b⟩ hp' (eq : a = x'),
have hp : (x', b) ∈ t, from eq ▸ hp',
show {p : α × α | p.fst = b → p.snd ∈ s} ∈ (@uniformity α _).sets,
from uniformity.upwards_sets ht $
assume ⟨a, b'⟩ hp' (heq : a = b),
have (b, b') ∈ t, from heq ▸ hp',
have (x', b') ∈ comp_rel t t, from ⟨b, hp, this⟩,
show b' ∈ s,
from tr this rfl,
hs⟩⟩
lemma nhds_eq_vmap_uniformity {x : α} : nhds x = uniformity.vmap (prod.mk x) :=
filter_eq $ set.ext $ assume s, by rw [mem_nhds_uniformity_iff, mem_vmap]; from iff.intro
(assume hs, ⟨_, hs, assume x hx, hx rfl⟩)
(assume ⟨t, h, ht⟩, uniformity.upwards_sets h $
assume ⟨p₁, p₂⟩ hp (h : p₁ = x), ht $ by simp [h.symm, hp])
lemma nhds_eq_uniformity {x : α} : nhds x = uniformity.lift' (λs:set (α×α), {y | (x, y) ∈ s}) :=
filter_eq $ set.ext $ assume s,
begin
rw [mem_lift'_iff], tactic.swap, apply monotone_preimage,
simp [mem_nhds_uniformity_iff],
exact ⟨assume h, ⟨_, h, assume y h, h rfl⟩,
assume ⟨t, h₁, h₂⟩,
uniformity.upwards_sets h₁ $
assume ⟨x', y⟩ hp (eq : x' = x), h₂ $
show (x, y) ∈ t, from eq ▸ hp⟩
end
lemma mem_nhds_left {x : α} {s : set (α×α)} (h : s ∈ (uniformity.sets : set (set (α×α)))) :
{y : α | (x, y) ∈ s} ∈ (nhds x).sets :=
have nhds x ≤ principal {y : α | (x, y) ∈ s},
by rw [nhds_eq_uniformity]; exact infi_le_of_le s (infi_le _ h),
by simp at this; assumption
lemma mem_nhds_right {y : α} {s : set (α×α)} (h : s ∈ (uniformity.sets : set (set (α×α)))) :
{x : α | (x, y) ∈ s} ∈ (nhds y).sets :=
mem_nhds_left (symm_le_uniformity h)
lemma tendsto_right_nhds_uniformity {a : α} : tendsto (λa', (a', a)) (nhds a) uniformity :=
assume s hs, show {a' | (a', a) ∈ s} ∈ (nhds a).sets, from mem_nhds_right hs
lemma tendsto_left_nhds_uniformity {a : α} : tendsto (λa', (a, a')) (nhds a) uniformity :=
assume s hs, show {a' | (a, a') ∈ s} ∈ (nhds a).sets, from mem_nhds_left hs
lemma lift_nhds_left {x : α} {g : set α → filter β} (hg : monotone g) :
(nhds x).lift g = uniformity.lift (λs:set (α×α), g {y | (x, y) ∈ s}) :=
eq.trans
begin
rw [nhds_eq_uniformity],
exact (filter.lift_assoc $ monotone_comp monotone_preimage $ monotone_comp monotone_preimage monotone_principal)
end
(congr_arg _ $ funext $ assume s, filter.lift_principal hg)
lemma lift_nhds_right {x : α} {g : set α → filter β} (hg : monotone g) :
(nhds x).lift g = uniformity.lift (λs:set (α×α), g {y | (y, x) ∈ s}) :=
calc (nhds x).lift g = uniformity.lift (λs:set (α×α), g {y | (x, y) ∈ s}) : lift_nhds_left hg
... = ((@prod.swap α α) <$> uniformity).lift (λs:set (α×α), g {y | (x, y) ∈ s}) : by rw [←uniformity_eq_symm]
... = uniformity.lift (λs:set (α×α), g {y | (x, y) ∈ image prod.swap s}) :
map_lift_eq2 $ monotone_comp monotone_preimage hg
... = _ : by simp [image_swap_eq_preimage_swap]
lemma nhds_nhds_eq_uniformity_uniformity_prod {a b : α} :
filter.prod (nhds a) (nhds b) =
uniformity.lift (λs:set (α×α), uniformity.lift' (λt:set (α×α),
set.prod {y : α | (y, a) ∈ s} {y : α | (b, y) ∈ t})) :=
show (nhds a).lift (λs:set α, (nhds b).lift (λt:set α, principal (set.prod s t))) = _,
begin
rw [lift_nhds_right],
apply congr_arg, apply funext, intro s,
rw [lift_nhds_left],
refl,
exact monotone_comp (monotone_prod monotone_const monotone_id) monotone_principal,
exact (monotone_lift' monotone_const $ monotone_lam $
assume x, monotone_prod monotone_id monotone_const)
end
lemma nhds_eq_uniformity_prod {a b : α} :
nhds (a, b) =
uniformity.lift' (λs:set (α×α), set.prod {y : α | (y, a) ∈ s} {y : α | (b, y) ∈ s}) :=
begin
rw [nhds_prod_eq, nhds_nhds_eq_uniformity_uniformity_prod, lift_lift'_same_eq_lift'],
{ intro s, exact monotone_prod monotone_const monotone_preimage },
{ intro t, exact monotone_prod monotone_preimage monotone_const }
end
lemma nhdset_of_mem_uniformity {d : set (α×α)} (s : set (α×α)) (hd : d ∈ (@uniformity α _).sets) :
∃(t : set (α×α)), is_open t ∧ s ⊆ t ∧ t ⊆ {p | ∃x y, (p.1, x) ∈ d ∧ (x, y) ∈ s ∧ (y, p.2) ∈ d} :=
let cl_d := {p:α×α | ∃x y, (p.1, x) ∈ d ∧ (x, y) ∈ s ∧ (y, p.2) ∈ d} in
have ∀p ∈ s, ∃t ⊆ cl_d, is_open t ∧ p ∈ t, from
assume ⟨x, y⟩ hp, mem_nhds_sets_iff.mp $
show cl_d ∈ (nhds (x, y)).sets,
begin
rw [nhds_eq_uniformity_prod, mem_lift'_iff],
exact ⟨d, hd, assume ⟨a, b⟩ ⟨ha, hb⟩, ⟨x, y, ha, hp, hb⟩⟩,
exact monotone_prod monotone_preimage monotone_preimage
end,
have ∃t:(Π(p:α×α) (h:p ∈ s), set (α×α)),
∀p, ∀h:p ∈ s, t p h ⊆ cl_d ∧ is_open (t p h) ∧ p ∈ t p h,
by simp [classical.skolem] at this; simp; assumption,
match this with
| ⟨t, ht⟩ :=
⟨(⋃ p:α×α, ⋃ h : p ∈ s, t p h : set (α×α)),
is_open_Union $ assume (p:α×α), is_open_Union $ assume hp, (ht p hp).right.left,
assume ⟨a, b⟩ hp, begin simp; exact ⟨a, b, hp, (ht (a,b) hp).right.right⟩ end,
Union_subset $ assume p, Union_subset $ assume hp, (ht p hp).left⟩
end
lemma closure_eq_inter_uniformity {t : set (α×α)} :
closure t = (⋂ d∈(@uniformity α _).sets, comp_rel d (comp_rel t d)) :=
set.ext $ assume ⟨a, b⟩,
calc (a, b) ∈ closure t ↔ (nhds (a, b) ⊓ principal t ≠ ⊥) : by simp [closure_eq_nhds]
... ↔ (((@prod.swap α α) <$> uniformity).lift'
(λ (s : set (α × α)), set.prod {x : α | (x, a) ∈ s} {y : α | (b, y) ∈ s}) ⊓ principal t ≠ ⊥) :
by rw [←uniformity_eq_symm, nhds_eq_uniformity_prod]
... ↔ ((map (@prod.swap α α) uniformity).lift'
(λ (s : set (α × α)), set.prod {x : α | (x, a) ∈ s} {y : α | (b, y) ∈ s}) ⊓ principal t ≠ ⊥) :
by refl
... ↔ (uniformity.lift'
(λ (s : set (α × α)), set.prod {y : α | (a, y) ∈ s} {x : α | (x, b) ∈ s}) ⊓ principal t ≠ ⊥) :
begin
rw [map_lift'_eq2],
simp [image_swap_eq_preimage_swap, function.comp],
exact monotone_prod monotone_preimage monotone_preimage
end
... ↔ (∀s∈(@uniformity α _).sets, ∃x, x ∈ set.prod {y : α | (a, y) ∈ s} {x : α | (x, b) ∈ s} ∩ t) :
begin
rw [lift'_inf_principal_eq, lift'_neq_bot_iff],
apply forall_congr, intro s, rw [ne_empty_iff_exists_mem],
exact monotone_inter (monotone_prod monotone_preimage monotone_preimage) monotone_const
end
... ↔ (∀s∈(@uniformity α _).sets, (a, b) ∈ comp_rel s (comp_rel t s)) :
forall_congr $ assume s, forall_congr $ assume hs,
⟨assume ⟨⟨x, y⟩, ⟨⟨hx, hy⟩, hxyt⟩⟩, ⟨x, hx, y, hxyt, hy⟩,
assume ⟨x, hx, y, hxyt, hy⟩, ⟨⟨x, y⟩, ⟨⟨hx, hy⟩, hxyt⟩⟩⟩
... ↔ _ : by simp
lemma uniformity_eq_uniformity_closure : (@uniformity α _) = uniformity.lift' closure :=
le_antisymm
(le_infi $ assume s, le_infi $ assume hs, by simp; exact uniformity.upwards_sets hs subset_closure)
(calc uniformity.lift' closure ≤ uniformity.lift' (λd, comp_rel d (comp_rel d d)) :
lift'_mono' (by intros s hs; rw [closure_eq_inter_uniformity]; exact bInter_subset_of_mem hs)
... ≤ uniformity : comp_le_uniformity3)
lemma uniformity_eq_uniformity_interior : (@uniformity α _) = uniformity.lift' interior :=
le_antisymm
(le_infi $ assume d, le_infi $ assume hd,
let ⟨s, hs, hs_comp⟩ := (mem_lift'_iff $
monotone_comp_rel monotone_id $ monotone_comp_rel monotone_id monotone_id).mp (comp_le_uniformity3 hd) in
let ⟨t, ht, hst, ht_comp⟩ := nhdset_of_mem_uniformity s hs in
have s ⊆ interior d, from
calc s ⊆ t : hst
... ⊆ interior d : (subset_interior_iff_subset_of_open ht).mpr $
assume x, assume : x ∈ t, let ⟨x, y, h₁, h₂, h₃⟩ := ht_comp this in hs_comp ⟨x, h₁, y, h₂, h₃⟩,
have interior d ∈ (@uniformity α _).sets,
from (@uniformity α _).upwards_sets hs $ this,
by simp [this])
(assume s hs, (uniformity.lift' interior).upwards_sets (mem_lift' hs) interior_subset)
lemma interior_mem_uniformity {s : set (α × α)} (hs : s ∈ (@uniformity α _).sets) :
interior s ∈ (@uniformity α _).sets :=
by rw [uniformity_eq_uniformity_interior]; exact mem_lift' hs
lemma mem_uniformity_is_closed [uniform_space α] {s : set (α×α)} (h : s ∈ (@uniformity α _).sets) :
∃t∈(@uniformity α _).sets, is_closed t ∧ t ⊆ s :=
have s ∈ ((@uniformity α _).lift' closure).sets, by rwa [uniformity_eq_uniformity_closure] at h,
have ∃t∈(@uniformity α _).sets, closure t ⊆ s,
by rwa [mem_lift'_iff] at this; apply closure_mono,
let ⟨t, ht, hst⟩ := this in
⟨closure t, uniformity.upwards_sets ht subset_closure, is_closed_closure, hst⟩
/- uniform continuity -/
definition uniform_continuous [uniform_space β] (f : α → β) :=
tendsto (λx:α×α, (f x.1, f x.2)) uniformity uniformity
lemma uniform_continuous_id : uniform_continuous (@id α) :=
by simp [uniform_continuous]; exact tendsto_id
lemma uniform_continuous_const [uniform_space β] {b : β} : uniform_continuous (λa:α, b) :=
@tendsto_const_uniformity _ _ _ b uniformity
lemma uniform_continuous_compose [uniform_space β] [uniform_space γ] {f : α → β} {g : β → γ}
(hf : uniform_continuous f) (hg : uniform_continuous g) : uniform_continuous (g ∘ f) :=
tendsto_compose hf hg
definition uniform_embedding [uniform_space β] (f : α → β) :=
(∀a₁ a₂, f a₁ = f a₂ → a₁ = a₂) ∧
vmap (λx:α×α, (f x.1, f x.2)) uniformity = uniformity
lemma uniform_continuous_of_embedding [uniform_space β] {f : α → β}
(hf : uniform_embedding f) : uniform_continuous f :=
by simp [uniform_continuous, hf.right.symm]; exact tendsto_vmap
lemma dense_embedding_of_uniform_embedding [uniform_space β] {f : α → β}
(h : uniform_embedding f) (hd : ∀x, x ∈ closure (f '' univ)) : dense_embedding f :=
{ dense_embedding .
dense := hd,
inj := h.left,
induced :=
begin
intro a,
simp [h.right.symm, nhds_eq_uniformity],
rw [vmap_lift'_eq, vmap_lift'_eq2],
refl,
exact monotone_preimage,
exact monotone_preimage
end }
lemma continuous_of_uniform [uniform_space β] {f : α → β}
(hf : uniform_continuous f) : continuous f :=
continuous_iff_tendsto.mpr $ assume a,
calc map f (nhds a) ≤
(map (λp:α×α, (f p.1, f p.2)) uniformity).lift' (λs:set (β×β), {y | (f a, y) ∈ s}) :
begin
rw [nhds_eq_uniformity, map_lift'_eq, map_lift'_eq2],
exact (lift'_mono' $ assume s hs b ⟨a', (ha' : (_, a') ∈ s), a'_eq⟩,
⟨(a, a'), ha', show (f a, f a') = (f a, b), from a'_eq ▸ rfl⟩),
exact monotone_preimage,
exact monotone_preimage
end
... ≤ nhds (f a) :
by rw [nhds_eq_uniformity]; exact lift'_mono hf (le_refl _)
lemma closure_image_mem_nhds_of_uniform_embedding
[uniform_space α] [uniform_space β] {s : set (α×α)} {e : α → β} (b : β)
(he₁ : uniform_embedding e) (he₂ : dense_embedding e) (hs : s ∈ (@uniformity α _).sets) :
∃a, closure (e '' {a' | (a, a') ∈ s}) ∈ (nhds b).sets :=
have s ∈ (vmap (λp:α×α, (e p.1, e p.2)) $ uniformity).sets,
from he₁.right.symm ▸ hs,
let ⟨t₁, ht₁u, ht₁⟩ := this in
have ht₁ : ∀p:α×α, (e p.1, e p.2) ∈ t₁ → p ∈ s, from ht₁,
let ⟨t₂, ht₂u, ht₂s, ht₂c⟩ := comp_symm_of_uniformity ht₁u in
let ⟨t, htu, hts, htc⟩ := comp_symm_of_uniformity ht₂u in
have preimage e {b' | (b, b') ∈ t₂} ∈ (vmap e $ nhds b).sets,
from preimage_mem_vmap $ mem_nhds_left ht₂u,
let ⟨a, (ha : (b, e a) ∈ t₂)⟩ := inhabited_of_mem_sets (he₂.vmap_nhds_neq_bot) this in
have ∀b' (s' : set (β × β)), (b, b') ∈ t → s' ∈ (@uniformity β _).sets →
{y : β | (b', y) ∈ s'} ∩ e '' {a' : α | (a, a') ∈ s} ≠ ∅,
from assume b' s' hb' hs',
have preimage e {b'' | (b', b'') ∈ s' ∩ t} ∈ (vmap e $ nhds b').sets,
from preimage_mem_vmap $ mem_nhds_left $ inter_mem_sets hs' htu,
let ⟨a₂, ha₂s', ha₂t⟩ := inhabited_of_mem_sets (he₂.vmap_nhds_neq_bot) this in
have (e a, e a₂) ∈ t₁,
from ht₂c $ prod_mk_mem_comp_rel (ht₂s ha) $ htc $ prod_mk_mem_comp_rel hb' ha₂t,
have e a₂ ∈ {b'':β | (b', b'') ∈ s'} ∩ e '' {a' | (a, a') ∈ s},
from ⟨ha₂s', mem_image_of_mem _ $ ht₁ (a, a₂) this⟩,
ne_empty_of_mem this,
have ∀b', (b, b') ∈ t → nhds b' ⊓ principal (e '' {a' | (a, a') ∈ s}) ≠ ⊥,
begin
intros b' hb',
rw [nhds_eq_uniformity, lift'_inf_principal_eq, lift'_neq_bot_iff],
exact assume s, this b' s hb',
exact monotone_inter monotone_preimage monotone_const
end,
have ∀b', (b, b') ∈ t → b' ∈ closure (e '' {a' | (a, a') ∈ s}),
from assume b' hb', by rw [closure_eq_nhds]; exact this b' hb',
⟨a, (nhds b).upwards_sets (mem_nhds_left htu) this⟩
/- cauchy filters -/
definition cauchy (f : filter α) := f ≠ ⊥ ∧ filter.prod f f ≤ uniformity
lemma cauchy_iff [uniform_space α] {f : filter α} :
cauchy f ↔ (f ≠ ⊥ ∧ (∀s∈(@uniformity α _).sets, ∃t∈f.sets, set.prod t t ⊆ s)) :=
and_congr (iff.refl _) $ forall_congr $ assume s, forall_congr $ assume hs, mem_prod_same_iff
lemma cauchy_downwards {f g : filter α} (h_c : cauchy f) (hg : g ≠ ⊥) (h_le : g ≤ f) : cauchy g :=
⟨hg, le_trans (filter.prod_mono h_le h_le) h_c.right⟩
lemma cauchy_nhds {a : α} : cauchy (nhds a) :=
⟨nhds_neq_bot,
calc filter.prod (nhds a) (nhds a) =
uniformity.lift (λs:set (α×α), uniformity.lift' (λt:set(α×α),
set.prod {y : α | (y, a) ∈ s} {y : α | (a, y) ∈ t})) : nhds_nhds_eq_uniformity_uniformity_prod
... ≤ uniformity.lift' (λs:set (α×α), comp_rel s s) :
le_infi $ assume s, le_infi $ assume hs,
infi_le_of_le s $ infi_le_of_le hs $ infi_le_of_le s $ infi_le_of_le hs $
principal_mono.mpr $
assume ⟨x, y⟩ ⟨(hx : (x, a) ∈ s), (hy : (a, y) ∈ s)⟩, ⟨a, hx, hy⟩
... ≤ uniformity : comp_le_uniformity⟩
lemma cauchy_pure {a : α} : cauchy (pure a) :=
cauchy_downwards cauchy_nhds
(show principal {a} ≠ ⊥, by simp)
(return_le_nhds a)
lemma le_nhds_of_cauchy_adhp {f : filter α} {x : α} (hf : cauchy f)
(adhs : f ⊓ nhds x ≠ ⊥) : f ≤ nhds x :=
have ∀s∈f.sets, x ∈ closure s,
begin
intros s hs,
simp [closure_eq_nhds, inf_comm],
exact assume h', adhs $ bot_unique $ h' ▸ inf_le_inf (by simp; exact hs) (le_refl _)
end,
calc f ≤ f.lift' (λs:set α, {y | x ∈ closure s ∧ y ∈ closure s}) :
le_infi $ assume s, le_infi $ assume hs,
begin
rw [←forall_sets_neq_empty_iff_neq_bot] at adhs,
simp [this s hs],
exact f.upwards_sets hs subset_closure
end
... ≤ f.lift' (λs:set α, {y | (x, y) ∈ closure (set.prod s s)}) :
by simp [closure_prod_eq]; exact le_refl _
... = (filter.prod f f).lift' (λs:set (α×α), {y | (x, y) ∈ closure s}) :
begin
rw [prod_same_eq],
rw [lift'_lift'_assoc],
exact monotone_prod monotone_id monotone_id,
exact monotone_comp (assume s t h x h', closure_mono h h') monotone_preimage
end
... ≤ uniformity.lift' (λs:set (α×α), {y | (x, y) ∈ closure s}) : lift'_mono hf.right (le_refl _)
... = (uniformity.lift' closure).lift' (λs:set (α×α), {y | (x, y) ∈ s}) :
begin
rw [lift'_lift'_assoc],
exact assume s t h, closure_mono h,
exact monotone_preimage
end
... = uniformity.lift' (λs:set (α×α), {y | (x, y) ∈ s}) :
by rw [←uniformity_eq_uniformity_closure]
... = nhds x :
by rw [nhds_eq_uniformity]
lemma le_nhds_iff_adhp_of_cauchy {f : filter α} {x : α} (hf : cauchy f) :
f ≤ nhds x ↔ f ⊓ nhds x ≠ ⊥ :=
⟨assume h, (inf_of_le_left h).symm ▸ hf.left,
le_nhds_of_cauchy_adhp hf⟩
lemma cauchy_map [uniform_space β] {f : filter α} {m : α → β}
(hm : uniform_continuous m) (hf : cauchy f) : cauchy (map m f) :=
⟨have f ≠ ⊥, from hf.left, by simp; assumption,
calc filter.prod (map m f) (map m f) =
map (λp:α×α, (m p.1, m p.2)) (filter.prod f f) : filter.prod_map_map_eq
... ≤ map (λp:α×α, (m p.1, m p.2)) uniformity : map_mono hf.right
... ≤ uniformity : hm⟩
lemma cauchy_vmap [uniform_space β] {f : filter β} {m : α → β}
(hm : vmap (λp:α×α, (m p.1, m p.2)) uniformity ≤ uniformity)
(hf : cauchy f) (hb : vmap m f ≠ ⊥) : cauchy (vmap m f) :=
⟨hb,
calc filter.prod (vmap m f) (vmap m f) =
vmap (λp:α×α, (m p.1, m p.2)) (filter.prod f f) : filter.prod_vmap_vmap_eq
... ≤ vmap (λp:α×α, (m p.1, m p.2)) uniformity : vmap_mono hf.right
... ≤ uniformity : hm⟩
/- separated uniformity -/
protected def separation_rel (α : Type u) [u : uniform_space α] :=
(⋂₀ (@uniformity α _).sets)
lemma separated_equiv : equivalence (λx y, (x, y) ∈ separation_rel α) :=
⟨assume x, assume s, refl_mem_uniformity,
assume x y, assume h (s : set (α×α)) hs,
have preimage prod.swap s ∈ (@uniformity α _).sets,
from symm_le_uniformity hs,
h _ this,
assume x y z (hxy : (x, y) ∈ separation_rel α) (hyz : (y, z) ∈ separation_rel α)
s (hs : s ∈ (@uniformity α _).sets),
let ⟨t, ht, (h_ts : comp_rel t t ⊆ s)⟩ := comp_mem_uniformity_sets hs in
h_ts $ show (x, z) ∈ comp_rel t t,
from ⟨y, hxy t ht, hyz t ht⟩⟩
protected def separation_setoid (α : Type u) [u : uniform_space α] : setoid α :=
⟨λx y, (x, y) ∈ separation_rel α, separated_equiv⟩
@[class] definition separated (α : Type u) [u : uniform_space α] :=
separation_rel α = id_rel
instance separated_t2 [s : separated α] : t2_space α :=
⟨assume x y, assume h : x ≠ y,
have separation_rel α = id_rel,
from s,
have (x, y) ∉ separation_rel α,
by simp [this]; exact h,
let ⟨d, hd, (hxy : (x, y) ∉ d)⟩ := classical.not_ball.1 this in
let ⟨d', hd', (hd'd' : comp_rel d' d' ⊆ d)⟩ := comp_mem_uniformity_sets hd in
have {y | (x, y) ∈ d'} ∈ (nhds x).sets,
from mem_nhds_left hd',
let ⟨u, hu₁, hu₂, hu₃⟩ := mem_nhds_sets_iff.mp this in
have {x | (x, y) ∈ d'} ∈ (nhds y).sets,
from mem_nhds_right hd',
let ⟨v, hv₁, hv₂, hv₃⟩ := mem_nhds_sets_iff.mp this in
have u ∩ v = ∅, from
eq_empty_of_subset_empty $
assume z ⟨(h₁ : z ∈ u), (h₂ : z ∈ v)⟩,
have (x, y) ∈ comp_rel d' d', from ⟨z, hu₁ h₁, hv₁ h₂⟩,
hxy $ hd'd' this,
⟨u, v, hu₂, hv₂, hu₃, hv₃, this⟩⟩
instance separated_regular [separated α] : regular_space α :=
{ separated_t2 with
regular := λs a hs ha,
have -s ∈ (nhds a).sets,
from mem_nhds_sets hs ha,
have {p : α × α | p.1 = a → p.2 ∈ -s} ∈ uniformity.sets,
from mem_nhds_uniformity_iff.mp this,
let ⟨d, hd, h⟩ := comp_mem_uniformity_sets this in
let e := {y:α| (a, y) ∈ d} in
have hae : a ∈ closure e, from subset_closure $ refl_mem_uniformity hd,
have set.prod (closure e) (closure e) ⊆ comp_rel d (comp_rel (set.prod e e) d),
begin
rw [←closure_prod_eq, closure_eq_inter_uniformity],
change (⨅d' ∈ uniformity.sets, _) ≤ comp_rel d (comp_rel _ d),
exact (infi_le_of_le d $ infi_le_of_le hd $ le_refl _)
end,
have e_subset : closure e ⊆ -s,
from assume a' ha',
let ⟨x, (hx : (a, x) ∈ d), y, ⟨hx₁, hx₂⟩, (hy : (y, _) ∈ d)⟩ := @this ⟨a, a'⟩ ⟨hae, ha'⟩ in
have (a, a') ∈ comp_rel d d, from ⟨y, hx₂, hy⟩,
h this rfl,
have closure e ∈ (nhds a).sets, from (nhds a).upwards_sets (mem_nhds_left hd) subset_closure,
have nhds a ⊓ principal (-closure e) = ⊥,
from (@inf_eq_bot_iff_le_compl _ _ _ (principal (- closure e)) (principal (closure e))
(by simp [principal_univ]) (by simp)).mpr (by simp [this]),
⟨- closure e, is_closed_closure, assume x h₁ h₂, @e_subset x h₂ h₁, this⟩ }
/- totally bounded -/
def totally_bounded (s : set α) : Prop :=
∀d ∈ (@uniformity α _).sets, ∃t : set α, finite t ∧ s ⊆ (⋃y∈t, {x | (x,y) ∈ d})
lemma totally_bounded_subset [uniform_space α] {s₁ s₂ : set α} (hs : s₁ ⊆ s₂)
(h : totally_bounded s₂) : totally_bounded s₁ :=
assume d hd, let ⟨t, ht₁, ht₂⟩ := h d hd in ⟨t, ht₁, subset.trans hs ht₂⟩
lemma totally_bounded_closure [uniform_space α] {s : set α} (h : totally_bounded s) :
totally_bounded (closure s) :=
assume t ht,
let ⟨t', ht', hct', htt'⟩ := mem_uniformity_is_closed ht, ⟨c, hcf, hc⟩ := h t' ht' in
⟨c, hcf,
calc closure s ⊆ closure (⋃ (y : α) (H : y ∈ c), {x : α | (x, y) ∈ t'}) : closure_mono hc
... = _ : closure_eq_of_is_closed $ is_closed_Union hcf $ assume i hi,
continuous_iff_is_closed.mp (continuous_prod_mk continuous_id continuous_const) _ hct'
... ⊆ _ : bUnion_subset $ assume i hi, subset.trans (assume x, @htt' (x, i))
(subset_bUnion_of_mem hi)⟩
lemma totally_bounded_image [uniform_space α] [uniform_space β] {f : α → β} {s : set α}
(hf : uniform_continuous f) (hs : totally_bounded s) : totally_bounded (f '' s) :=
assume t ht,
have {p:α×α | (f p.1, f p.2) ∈ t} ∈ (@uniformity α _).sets,
from hf ht,
let ⟨c, hfc, hct⟩ := hs _ this in
⟨f '' c, finite_image hfc,
begin
simp [image_subset_iff],
simp [subset_def] at hct,
intros x hx, simp [-mem_image],
exact let ⟨i, hi, ht⟩ := hct x hx in ⟨f i, mem_image_of_mem f hi, ht⟩
end⟩
lemma cauchy_of_totally_bounded_of_ultrafilter {s : set α} {f : filter α}
(hs : totally_bounded s) (hf : ultrafilter f) (h : f ≤ principal s) : cauchy f :=
⟨hf.left, assume t ht,
let ⟨t', ht'₁, ht'_symm, ht'_t⟩ := comp_symm_of_uniformity ht in
let ⟨i, hi, hs_union⟩ := hs t' ht'₁ in
have (⋃y∈i, {x | (x,y) ∈ t'}) ∈ f.sets,
from f.upwards_sets (le_principal_iff.mp h) hs_union,
have ∃y∈i, {x | (x,y) ∈ t'} ∈ f.sets,
from mem_of_finite_Union_ultrafilter hf hi this,
let ⟨y, hy, hif⟩ := this in
have set.prod {x | (x,y) ∈ t'} {x | (x,y) ∈ t'} ⊆ comp_rel t' t',
from assume ⟨x₁, x₂⟩ ⟨(h₁ : (x₁, y) ∈ t'), (h₂ : (x₂, y) ∈ t')⟩,
⟨y, h₁, ht'_symm h₂⟩,
(filter.prod f f).upwards_sets (prod_mem_prod hif hif) (subset.trans this ht'_t)⟩
lemma totally_bounded_iff_filter {s : set α} :
totally_bounded s ↔ (∀f, f ≠ ⊥ → f ≤ principal s → ∃c ≤ f, cauchy c) :=
⟨assume : totally_bounded s, assume f hf hs,
⟨ultrafilter_of f, ultrafilter_of_le,
cauchy_of_totally_bounded_of_ultrafilter this
(ultrafilter_ultrafilter_of hf) (le_trans ultrafilter_of_le hs)⟩,
assume h : ∀f, f ≠ ⊥ → f ≤ principal s → ∃c ≤ f, cauchy c, assume d hd,
classical.by_contradiction $ assume hs,
have hd_cover : ∀{t:set α}, finite t → ¬ s ⊆ (⋃y∈t, {x | (x,y) ∈ d}),
by simpa using hs,
let
f := ⨅t:{t : set α // finite t}, principal (s \ (⋃y∈t.val, {x | (x,y) ∈ d})),
⟨a, ha⟩ := @exists_mem_of_ne_empty α s
(assume h, hd_cover finite.empty $ h.symm ▸ empty_subset _)
in
have f ≠ ⊥,
from infi_neq_bot_of_directed ⟨a⟩
(assume ⟨t₁, ht₁⟩ ⟨t₂, ht₂⟩, ⟨⟨t₁ ∪ t₂, finite_union ht₁ ht₂⟩,
principal_mono.mpr $ diff_right_antimono $ Union_subset_Union $
assume t, Union_subset_Union_const or.inl,
principal_mono.mpr $ diff_right_antimono $ Union_subset_Union $
assume t, Union_subset_Union_const or.inr⟩)
(assume ⟨t, ht⟩, by simp [diff_neq_empty]; exact hd_cover ht),
have f ≤ principal s, from infi_le_of_le ⟨∅, finite.empty⟩ $ by simp; exact subset.refl s,
let
⟨c, (hc₁ : c ≤ f), (hc₂ : cauchy c)⟩ := h f ‹f ≠ ⊥› this,
⟨m, hm, (hmd : set.prod m m ⊆ d)⟩ := (@mem_prod_same_iff α c d).mp $ hc₂.right hd
in
have c ≤ principal s, from le_trans ‹c ≤ f› this,
have m ∩ s ∈ c.sets, from inter_mem_sets hm $ le_principal_iff.mp this,
let ⟨y, hym, hys⟩ := inhabited_of_mem_sets hc₂.left this in
let ys := (⋃y'∈({y}:set α), {x | (x, y') ∈ d}) in
have m ⊆ ys,
from assume y' hy',
show y' ∈ (⋃y'∈({y}:set α), {x | (x, y') ∈ d}),
by simp; exact @hmd (y', y) ⟨hy', hym⟩,
have c ≤ principal (s - ys),
from le_trans hc₁ $ infi_le_of_le ⟨{y}, finite_insert finite.empty⟩ $ le_refl _,
have (s - ys) ∩ (m ∩ s) ∈ c.sets,
from inter_mem_sets (le_principal_iff.mp this) ‹m ∩ s ∈ c.sets›,
have ∅ ∈ c.sets,
from c.upwards_sets this $ assume x ⟨⟨hxs, hxys⟩, hxm, _⟩, hxys $ ‹m ⊆ ys› hxm,
hc₂.left $ empty_in_sets_eq_bot.mp this⟩
lemma totally_bounded_iff_ultrafilter {s : set α} :
totally_bounded s ↔ (∀f, ultrafilter f → f ≤ principal s → cauchy f) :=
⟨assume hs f, cauchy_of_totally_bounded_of_ultrafilter hs,
assume h, totally_bounded_iff_filter.mpr $ assume f hf hfs,
have cauchy (ultrafilter_of f),
from h (ultrafilter_of f) (ultrafilter_ultrafilter_of hf) (le_trans ultrafilter_of_le hfs),
⟨ultrafilter_of f, ultrafilter_of_le, this⟩⟩
lemma compact_of_totally_bounded_complete {s : set α}
(ht : totally_bounded s) (hc : ∀{f:filter α}, cauchy f → f ≤ principal s → ∃x∈s, f ≤ nhds x) :
compact s :=
begin
rw [compact_iff_ultrafilter_le_nhds],
rw [totally_bounded_iff_ultrafilter] at ht,
exact assume f hf hfs, hc (ht _ hf hfs) hfs
end
/- complete space -/
class complete_space (α : Type u) [uniform_space α] : Prop :=
(complete : ∀{f:filter α}, cauchy f → ∃x, f ≤ nhds x)
lemma complete_of_is_closed [complete_space α] {s : set α} {f : filter α}
(h : is_closed s) (hf : cauchy f) (hfs : f ≤ principal s) : ∃x∈s, f ≤ nhds x :=
let ⟨x, hx⟩ := complete_space.complete hf in
have x ∈ s, from is_closed_iff_nhds.mp h x $ neq_bot_of_le_neq_bot hf.left $
le_inf hx hfs,
⟨x, this, hx⟩
lemma compact_of_totally_bounded_is_closed [complete_space α] {s : set α}
(ht : totally_bounded s) (hc : is_closed s) : compact s :=
@compact_of_totally_bounded_complete α _ s ht $ assume f, complete_of_is_closed hc
lemma complete_space_extension [uniform_space β] {m : β → α}
(hm : uniform_embedding m)
(dense : ∀x, x ∈ closure (m '' univ))
(h : ∀f:filter β, cauchy f → ∃x:α, map m f ≤ nhds x) :
complete_space α :=
⟨assume (f : filter α), assume hf : cauchy f,
let
p : set (α × α) → set α → set α := λs t, {y : α| ∃x:α, x ∈ t ∧ (x, y) ∈ s},
g := uniformity.lift (λs, f.lift' (p s))
in
have mp₀ : monotone p,
from assume a b h t s ⟨x, xs, xa⟩, ⟨x, xs, h xa⟩,
have mp₁ : ∀{s}, monotone (p s),
from assume s a b h x ⟨y, ya, yxs⟩, ⟨y, h ya, yxs⟩,
have f ≤ g, from
le_infi $ assume s, le_infi $ assume hs, le_infi $ assume t, le_infi $ assume ht,
le_principal_iff.mpr $
f.upwards_sets ht $ assume x hx, ⟨x, hx, refl_mem_uniformity hs⟩,
have g ≠ ⊥, from neq_bot_of_le_neq_bot hf.left this,
have vmap m g ≠ ⊥, from vmap_neq_bot $ assume t ht,
let ⟨t', ht', ht_mem⟩ := (mem_lift_iff $ monotone_lift' monotone_const mp₀).mp ht in
let ⟨t'', ht'', ht'_sub⟩ := (mem_lift'_iff mp₁).mp ht_mem in
let ⟨x, (hx : x ∈ t'')⟩ := inhabited_of_mem_sets hf.left ht'' in
have h₀ : nhds x ⊓ principal (m '' univ) ≠ ⊥,
by simp [closure_eq_nhds] at dense; exact dense x,
have h₁ : {y | (x, y) ∈ t'} ∈ (nhds x ⊓ principal (m '' univ)).sets,
from @mem_inf_sets_of_left α (nhds x) (principal (m '' univ)) _ $ mem_nhds_left ht',
have h₂ : m '' univ ∈ (nhds x ⊓ principal (m '' univ)).sets,
from @mem_inf_sets_of_right α (nhds x) (principal (m '' univ)) _ $ subset.refl _,
have {y | (x, y) ∈ t'} ∩ m '' univ ∈ (nhds x ⊓ principal (m '' univ)).sets,
from @inter_mem_sets α (nhds x ⊓ principal (m '' univ)) _ _ h₁ h₂,
let ⟨y, xyt', b, _, b_eq⟩ := inhabited_of_mem_sets h₀ this in
⟨b, b_eq.symm ▸ ht'_sub ⟨x, hx, xyt'⟩⟩,
have cauchy g, from
⟨‹g ≠ ⊥›, assume s hs,
let
⟨s₁, hs₁, (comp_s₁ : comp_rel s₁ s₁ ⊆ s)⟩ := comp_mem_uniformity_sets hs,
⟨s₂, hs₂, (comp_s₂ : comp_rel s₂ s₂ ⊆ s₁)⟩ := comp_mem_uniformity_sets hs₁,
⟨t, ht, (prod_t : set.prod t t ⊆ s₂)⟩ := mem_prod_same_iff.mp (hf.right hs₂)
in
have hg₁ : p (preimage prod.swap s₁) t ∈ g.sets,
from mem_lift (symm_le_uniformity hs₁) $ @mem_lift' α α f _ t ht,
have hg₂ : p s₂ t ∈ g.sets,
from mem_lift hs₂ $ @mem_lift' α α f _ t ht,
have hg : set.prod (p (preimage prod.swap s₁) t) (p s₂ t) ∈ (filter.prod g g).sets,
from @prod_mem_prod α α _ _ g g hg₁ hg₂,
(filter.prod g g).upwards_sets hg
(assume ⟨a, b⟩ ⟨⟨c₁, c₁t, hc₁⟩, ⟨c₂, c₂t, hc₂⟩⟩,
have (c₁, c₂) ∈ set.prod t t, from ⟨c₁t, c₂t⟩,
comp_s₁ $ prod_mk_mem_comp_rel hc₁ $
comp_s₂ $ prod_mk_mem_comp_rel (prod_t this) hc₂)⟩,
have cauchy (filter.vmap m g),
from cauchy_vmap (le_of_eq hm.right) ‹cauchy g› (by assumption),
let ⟨x, (hx : map m (filter.vmap m g) ≤ nhds x)⟩ := h _ this in
have map m (filter.vmap m g) ⊓ nhds x ≠ ⊥,
from (le_nhds_iff_adhp_of_cauchy (cauchy_map (uniform_continuous_of_embedding hm) this)).mp hx,
have g ⊓ nhds x ≠ ⊥,
from neq_bot_of_le_neq_bot this (inf_le_inf (assume s hs, ⟨s, hs, subset.refl _⟩) (le_refl _)),
⟨x, calc f ≤ g : by assumption
... ≤ nhds x : le_nhds_of_cauchy_adhp ‹cauchy g› this⟩⟩
/- separation space -/
section separation_space
local attribute [instance] separation_setoid
instance {α : Type u} [u : uniform_space α] : uniform_space (quotient (separation_setoid α)) :=
{ uniform_space .
to_topological_space := u.to_topological_space.coinduced (λx, ⟦x⟧),
uniformity := map (λp:(α×α), (⟦p.1⟧, ⟦p.2⟧)) uniformity,
refl := assume s hs ⟨a, b⟩ (h : a = b),
have ∀a:α, (a, a) ∈ preimage (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧)) s,
from assume a, refl_mem_uniformity hs,
h ▸ quotient.induction_on a this,
symm := tendsto_map' $
by simp [prod.swap, (∘)]; exact tendsto_compose tendsto_swap_uniformity tendsto_map,
comp := calc (map (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧)) uniformity).lift' (λs, comp_rel s s) =
uniformity.lift' ((λs, comp_rel s s) ∘ image (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧))) :
map_lift'_eq2 $ monotone_comp_rel monotone_id monotone_id
... ≤ uniformity.lift' (image (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧)) ∘ (λs:set (α×α), comp_rel s (comp_rel s s))) :
lift'_mono' $ assume s hs ⟨a, b⟩ ⟨c, ⟨⟨a₁, a₂⟩, ha, a_eq⟩, ⟨⟨b₁, b₂⟩, hb, b_eq⟩⟩,
begin
simp at a_eq,
simp at b_eq,
have h : ⟦a₂⟧ = ⟦b₁⟧, { rw [a_eq.right, b_eq.left] },
have h : (a₂, b₁) ∈ separation_rel α := quotient.exact h,
simp [function.comp, set.image, comp_rel],
exact ⟨a₁, a_eq.left, b₂, b_eq.right, a₂, ha, b₁, h s hs, hb⟩
end
... = map (λp:(α×α), (⟦p.1⟧, ⟦p.2⟧)) (uniformity.lift' (λs:set (α×α), comp_rel s (comp_rel s s))) :
by rw [map_lift'_eq];
exact monotone_comp_rel monotone_id (monotone_comp_rel monotone_id monotone_id)
... ≤ map (λp:(α×α), (⟦p.1⟧, ⟦p.2⟧)) uniformity :
map_mono comp_le_uniformity3,
is_open_uniformity := assume s,
have ∀a, ⟦a⟧ ∈ s →
({p:α×α | p.1 = a → ⟦p.2⟧ ∈ s} ∈ (@uniformity α _).sets ↔
{p:α×α | ⟦p.1⟧ = ⟦a⟧ → ⟦p.2⟧ ∈ s} ∈ (@uniformity α _).sets),
from assume a ha,
⟨assume h,
let ⟨t, ht, hts⟩ := comp_mem_uniformity_sets h in
have hts : ∀{a₁ a₂}, (a, a₁) ∈ t → (a₁, a₂) ∈ t → ⟦a₂⟧ ∈ s,
from assume a₁ a₂ ha₁ ha₂, @hts (a, a₂) ⟨a₁, ha₁, ha₂⟩ rfl,
have ht' : ∀{a₁ a₂}, ⟦a₁⟧ = ⟦a₂⟧ → (a₁, a₂) ∈ t,
from assume a₁ a₂ h, sInter_subset_of_mem ht (quotient.exact h),
uniformity.upwards_sets ht $ assume ⟨a₁, a₂⟩ h₁ h₂, hts (ht' h₂.symm) h₁,
assume h, uniformity.upwards_sets h $ by simp {contextual := tt}⟩,
begin
simp [topological_space.coinduced, u.is_open_uniformity, uniformity, forall_quotient_iff],
exact ⟨λh a ha, (this a ha).mp $ h a ha, λh a ha, (this a ha).mpr $ h a ha⟩
end }
lemma uniform_continuous_quotient_mk :
uniform_continuous (quotient.mk : α → quotient (separation_setoid α)) :=
le_refl _
lemma vmap_quotient_le_uniformity : vmap (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧)) uniformity ≤ uniformity :=
assume t' ht',
let ⟨t, ht, tt_t'⟩ := comp_mem_uniformity_sets ht' in
let ⟨s, hs, ss_t⟩ := comp_mem_uniformity_sets ht in
⟨(λp:α×α, (⟦p.1⟧, ⟦p.2⟧)) '' s,
(@uniformity α _).upwards_sets hs $ assume x hx, ⟨x, hx, rfl⟩,
assume ⟨a₁, a₂⟩ ⟨⟨b₁, b₂⟩, hb, ab_eq⟩,
have ⟦b₁⟧ = ⟦a₁⟧ ∧ ⟦b₂⟧ = ⟦a₂⟧, from prod.mk.inj ab_eq,
have b₁ ≈ a₁ ∧ b₂ ≈ a₂, from and.imp quotient.exact quotient.exact this,
have ab₁ : (a₁, b₁) ∈ t, from (setoid.symm this.left) t ht,
have ba₂ : (b₂, a₂) ∈ s, from this.right s hs,
tt_t' ⟨b₁, show ((a₁, a₂).1, b₁) ∈ t, from ab₁,
ss_t ⟨b₂, show ((b₁, a₂).1, b₂) ∈ s, from hb, ba₂⟩⟩⟩
lemma vmap_quotient_eq_uniformity : vmap (λ (p : α × α), (⟦p.fst⟧, ⟦p.snd⟧)) uniformity = uniformity :=
le_antisymm vmap_quotient_le_uniformity
(assume s ⟨t, ht, hs⟩, uniformity.upwards_sets ht hs)
lemma complete_space_separation [h : complete_space α] :
complete_space (quotient (separation_setoid α)) :=
⟨assume f, assume hf : cauchy f,
have cauchy (vmap (λx, ⟦x⟧) f), from
cauchy_vmap vmap_quotient_le_uniformity hf $
vmap_neq_bot_of_surj hf.left $ assume b, quotient.exists_rep _,
let ⟨x, (hx : vmap (λx, ⟦x⟧) f ≤ nhds x)⟩ := complete_space.complete this in
⟨⟦x⟧, calc f ≤ map (λx, ⟦x⟧) (vmap (λx, ⟦x⟧) f) : le_map_vmap $ assume b, quotient.exists_rep _
... ≤ map (λx, ⟦x⟧) (nhds x) : map_mono hx
... ≤ _ : continuous_iff_tendsto.mp (continuous_of_uniform uniform_continuous_quotient_mk) _⟩⟩
lemma separated_separation [h : complete_space α] : separated (quotient (separation_setoid α)) :=
set.ext $ assume ⟨a, b⟩, quotient.induction_on₂ a b $ assume a b,
⟨assume h,
have a ≈ b, from assume s hs,
have s ∈ (vmap (λp:(α×α), (⟦p.1⟧, ⟦p.2⟧)) uniformity).sets,
from vmap_quotient_le_uniformity hs,
let ⟨t, ht, hts⟩ := this in
hts begin dsimp, exact h t ht end,
show ⟦a⟧ = ⟦b⟧, from quotient.sound this,
assume heq : ⟦a⟧ = ⟦b⟧, assume h hs,
heq ▸ refl_mem_uniformity hs⟩
end separation_space
section uniform_extension
variables
[uniform_space β]
[uniform_space γ]
{e : β → α}
(h_e : uniform_embedding e)
(h_dense : ∀x, x ∈ closure (e '' univ))
{f : β → γ}
(h_f : uniform_continuous f)
[inhabited γ]
local notation `ψ` := (dense_embedding_of_uniform_embedding h_e h_dense).ext f
lemma uniformly_extend_of_emb [cγ : complete_space γ] [sγ : separated γ] {b : β} :
ψ (e b) = f b :=
dense_embedding.ext_e_eq _ $ continuous_iff_tendsto.mp (continuous_of_uniform h_f) b
lemma uniformly_extend_exists [complete_space γ] [sγ : separated γ] {a : α} :
∃c, tendsto f (vmap e (nhds a)) (nhds c) :=
let de := (dense_embedding_of_uniform_embedding h_e h_dense) in
have cauchy (nhds a), from cauchy_nhds,
have cauchy (vmap e (nhds a)), from
cauchy_vmap (le_of_eq h_e.right) this de.vmap_nhds_neq_bot,
have cauchy (map f (vmap e (nhds a))), from
cauchy_map h_f this,
complete_space.complete this
lemma uniformly_extend_spec [complete_space γ] [sγ : separated γ] {a : α} :
tendsto f (vmap e (nhds a)) (nhds (ψ a)) :=
lim_spec $ uniformly_extend_exists h_e h_dense h_f
lemma uniform_continuous_uniformly_extend [cγ : complete_space γ] [sγ : separated γ] :
uniform_continuous ψ :=
assume d hd,
let ⟨s, hs, hs_comp⟩ := (mem_lift'_iff $
monotone_comp_rel monotone_id $ monotone_comp_rel monotone_id monotone_id).mp (comp_le_uniformity3 hd) in
have h_pnt : ∀{a m}, m ∈ (nhds a).sets → ∃c, c ∈ f '' preimage e m ∧ (c, ψ a) ∈ s ∧ (ψ a, c) ∈ s,
from assume a m hm,
have nb : map f (vmap e (nhds a)) ≠ ⊥,
from map_ne_bot (dense_embedding_of_uniform_embedding h_e h_dense).vmap_nhds_neq_bot,
have (f '' preimage e m) ∩ ({c | (c, ψ a) ∈ s } ∩ {c | (ψ a, c) ∈ s }) ∈ (map f (vmap e (nhds a))).sets,
from inter_mem_sets (image_mem_map $ preimage_mem_vmap $ hm)
(uniformly_extend_spec h_e h_dense h_f $ inter_mem_sets (mem_nhds_right hs) (mem_nhds_left hs)),
inhabited_of_mem_sets nb this,
have preimage (λp:β×β, (f p.1, f p.2)) s ∈ (@uniformity β _).sets,
from h_f hs,
have preimage (λp:β×β, (f p.1, f p.2)) s ∈ (vmap (λx:β×β, (e x.1, e x.2)) uniformity).sets,
by rwa [h_e.right.symm] at this,
let ⟨t, ht, ts⟩ := this in
show preimage (λp:(α×α), (ψ p.1, ψ p.2)) d ∈ uniformity.sets,
from (@uniformity α _).upwards_sets (interior_mem_uniformity ht) $
assume ⟨x₁, x₂⟩ hx_t,
have nhds (x₁, x₂) ≤ principal (interior t),
from is_open_iff_nhds.mp is_open_interior (x₁, x₂) hx_t,
have interior t ∈ (filter.prod (nhds x₁) (nhds x₂)).sets,
by rwa [nhds_prod_eq, le_principal_iff] at this,
let ⟨m₁, hm₁, m₂, hm₂, (hm : set.prod m₁ m₂ ⊆ interior t)⟩ := mem_prod_iff.mp this in
let ⟨a, ha₁, _, ha₂⟩ := h_pnt hm₁ in
let ⟨b, hb₁, hb₂, _⟩ := h_pnt hm₂ in
have set.prod (preimage e m₁) (preimage e m₂) ⊆ preimage (λp:(β×β), (f p.1, f p.2)) s,
from calc _ ⊆ preimage (λp:(β×β), (e p.1, e p.2)) (interior t) : preimage_mono hm
... ⊆ preimage (λp:(β×β), (e p.1, e p.2)) t : preimage_mono interior_subset
... ⊆ preimage (λp:(β×β), (f p.1, f p.2)) s : ts,
have set.prod (f '' preimage e m₁) (f '' preimage e m₂) ⊆ s,
from calc set.prod (f '' preimage e m₁) (f '' preimage e m₂) =
(λp:(β×β), (f p.1, f p.2)) '' (set.prod (preimage e m₁) (preimage e m₂)) : prod_image_image_eq
... ⊆ (λp:(β×β), (f p.1, f p.2)) '' preimage (λp:(β×β), (f p.1, f p.2)) s : mono_image this
... ⊆ s : image_subset_iff.mpr $ subset.refl _,
have (a, b) ∈ s, from @this (a, b) ⟨ha₁, hb₁⟩,
hs_comp $ show (ψ x₁, ψ x₂) ∈ comp_rel s (comp_rel s s),
from ⟨a, ha₂, ⟨b, this, hb₂⟩⟩
end uniform_extension
end uniform_space
end
/-- Space of Cauchy filters
This is essentially the completion of a uniform space. The embeddings are the neighbourhood filters.
This space is not minimal, the separated uniform space (i.e. quotiented on the intersection of all
entourages) is necessary for this.
-/
def Cauchy (α : Type u) [uniform_space α] : Type u := { f : filter α // cauchy f }
namespace Cauchy
section
parameters {α : Type u} [uniform_space α]
def gen (s : set (α × α)) : set (Cauchy α × Cauchy α) :=
{p | s ∈ (filter.prod (p.1.val) (p.2.val)).sets }
lemma monotone_gen : monotone gen :=
monotone_set_of $ assume p, @monotone_mem_sets (α×α) (filter.prod (p.1.val) (p.2.val))
private lemma symm_gen : map prod.swap (uniformity.lift' gen) ≤ uniformity.lift' gen :=
calc map prod.swap (uniformity.lift' gen) =
uniformity.lift' (λs:set (α×α), {p | s ∈ (filter.prod (p.2.val) (p.1.val)).sets }) :
begin
delta gen,
simp [map_lift'_eq, monotone_set_of, monotone_mem_sets,
function.comp, image_swap_eq_preimage_swap]
end
... ≤ uniformity.lift' gen :
uniformity_lift_le_swap
(monotone_comp (monotone_set_of $ assume p,
@monotone_mem_sets (α×α) ((filter.prod ((p.2).val) ((p.1).val)))) monotone_principal)
begin
have h := λ(p:Cauchy α×Cauchy α), @filter.prod_comm _ _ (p.2.val) (p.1.val),
simp [function.comp, h],
exact le_refl _
end
private lemma comp_rel_gen_gen_subset_gen_comp_rel {s t : set (α×α)} : comp_rel (gen s) (gen t) ⊆
(gen (comp_rel s t) : set (Cauchy α × Cauchy α)) :=
assume ⟨f, g⟩ ⟨h, h₁, h₂⟩,
let ⟨t₁, (ht₁ : t₁ ∈ f.val.sets), t₂, (ht₂ : t₂ ∈ h.val.sets), (h₁ : set.prod t₁ t₂ ⊆ s)⟩ :=
mem_prod_iff.mp h₁ in
let ⟨t₃, (ht₃ : t₃ ∈ h.val.sets), t₄, (ht₄ : t₄ ∈ g.val.sets), (h₂ : set.prod t₃ t₄ ⊆ t)⟩ :=
mem_prod_iff.mp h₂ in
have t₂ ∩ t₃ ∈ h.val.sets,
from inter_mem_sets ht₂ ht₃,
let ⟨x, xt₂, xt₃⟩ :=
inhabited_of_mem_sets (h.property.left) this in
(filter.prod f.val g.val).upwards_sets
(prod_mem_prod ht₁ ht₄)
(assume ⟨a, b⟩ ⟨(ha : a ∈ t₁), (hb : b ∈ t₄)⟩,
⟨x,
h₁ (show (a, x) ∈ set.prod t₁ t₂, from ⟨ha, xt₂⟩),
h₂ (show (x, b) ∈ set.prod t₃ t₄, from ⟨xt₃, hb⟩)⟩)
private lemma comp_gen :
(uniformity.lift' gen).lift' (λs, comp_rel s s) ≤ uniformity.lift' gen :=
calc (uniformity.lift' gen).lift' (λs, comp_rel s s) =
uniformity.lift' (λs, comp_rel (gen s) (gen s)) :
begin
rw [lift'_lift'_assoc],
exact monotone_gen,
exact (monotone_comp_rel monotone_id monotone_id)
end
... ≤ uniformity.lift' (λs, gen $ comp_rel s s) :
lift'_mono' $ assume s hs, comp_rel_gen_gen_subset_gen_comp_rel
... = (uniformity.lift' $ λs:set(α×α), comp_rel s s).lift' gen :
begin
rw [lift'_lift'_assoc],
exact (monotone_comp_rel monotone_id monotone_id),
exact monotone_gen
end
... ≤ uniformity.lift' gen : lift'_mono comp_le_uniformity (le_refl _)
instance completion_space : uniform_space (Cauchy α) :=
uniform_space.of_core
{ uniformity := uniformity.lift' gen,
refl := principal_le_lift' $ assume s hs ⟨a, b⟩ (a_eq_b : a = b),
a_eq_b ▸ a.property.right hs,
symm := symm_gen,
comp := comp_gen }
def pure_cauchy (a : α) : Cauchy α :=
⟨pure a, cauchy_pure⟩
lemma uniform_embedding_pure_cauchy : uniform_embedding (pure_cauchy : α → Cauchy α) :=
⟨assume a₁ a₂ h,
have (pure_cauchy a₁).val = (pure_cauchy a₂).val, from congr_arg _ h,
have {a₁} = ({a₂} : set α),
from principal_eq_iff_eq.mp this,
by simp at this; assumption,
have (preimage (λ (x : α × α), (pure_cauchy (x.fst), pure_cauchy (x.snd))) ∘ gen) = id,
from funext $ assume s, set.ext $ assume ⟨a₁, a₂⟩,
by simp [preimage, gen, pure_cauchy, prod_principal_principal],
calc vmap (λ (x : α × α), (pure_cauchy (x.fst), pure_cauchy (x.snd))) (uniformity.lift' gen)
= uniformity.lift' (preimage (λ (x : α × α), (pure_cauchy (x.fst), pure_cauchy (x.snd))) ∘ gen) :
vmap_lift'_eq monotone_gen
... = uniformity : by simp [this]⟩
lemma pure_cauchy_dense : ∀x, x ∈ closure (pure_cauchy '' univ) :=
assume f,
have h_ex : ∀s∈(@uniformity (Cauchy α) _).sets, ∃y:α, (f, pure_cauchy y) ∈ s, from
assume s hs,
let ⟨t'', ht''₁, (ht''₂ : gen t'' ⊆ s)⟩ := (mem_lift'_iff monotone_gen).mp hs in
let ⟨t', ht'₁, ht'₂⟩ := comp_mem_uniformity_sets ht''₁ in
have t' ∈ (filter.prod (f.val) (f.val)).sets,
from f.property.right ht'₁,
let ⟨t, ht, (h : set.prod t t ⊆ t')⟩ := mem_prod_same_iff.mp this in
let ⟨x, (hx : x ∈ t)⟩ := inhabited_of_mem_sets f.property.left ht in
have t'' ∈ (filter.prod f.val (pure x)).sets,
from mem_prod_iff.mpr ⟨t, ht, {y:α | (x, y) ∈ t'},
assume y, begin simp, intro h, simp [h], exact refl_mem_uniformity ht'₁ end,
assume ⟨a, b⟩ ⟨(h₁ : a ∈ t), (h₂ : (x, b) ∈ t')⟩,
ht'₂ $ prod_mk_mem_comp_rel (@h (a, x) ⟨h₁, hx⟩) h₂⟩,
⟨x, ht''₂ $ by dsimp [gen]; exact this⟩,
begin
simp [closure_eq_nhds, nhds_eq_uniformity, lift'_inf_principal_eq],
exact (lift'_neq_bot_iff $ monotone_inter monotone_const monotone_preimage).mpr
(assume s hs,
let ⟨y, hy⟩ := h_ex s hs in
have pure_cauchy y ∈ pure_cauchy '' univ ∩ {y : Cauchy α | (f, y) ∈ s},
from ⟨mem_image_of_mem _ $ mem_univ y, hy⟩,
ne_empty_of_mem this)
end
instance : complete_space (Cauchy α) :=
complete_space_extension
uniform_embedding_pure_cauchy
pure_cauchy_dense $
assume f hf,
let f' : Cauchy α := ⟨f, hf⟩ in
have map pure_cauchy f ≤ uniformity.lift' (preimage (prod.mk f')),
from le_lift' $ assume s hs,
let ⟨t, ht₁, (ht₂ : gen t ⊆ s)⟩ := (mem_lift'_iff monotone_gen).mp hs in
let ⟨t', ht', (h : set.prod t' t' ⊆ t)⟩ := mem_prod_same_iff.mp (hf.right ht₁) in
have t' ⊆ { y : α | (f', pure_cauchy y) ∈ gen t },
from assume x hx, (filter.prod f (pure x)).upwards_sets (prod_mem_prod ht' $ mem_pure hx) h,
f.upwards_sets ht' $ subset.trans this (preimage_mono ht₂),
⟨f', by simp [nhds_eq_uniformity]; assumption⟩
end
end Cauchy
instance nonempty_Cauchy {α : Type u} [h : nonempty α] [uniform_space α] : nonempty (Cauchy α) :=
h.rec_on $ assume a, nonempty.intro $ Cauchy.pure_cauchy a
instance inhabited_Cauchy {α : Type u} [inhabited α] [uniform_space α] : inhabited (Cauchy α) :=
⟨Cauchy.pure_cauchy $ default α⟩
section constructions
variables {α : Type*} {β : Type*} {γ : Type*} {δ : Type*} {ι : Sort*}
instance : partial_order (uniform_space α) :=
{ le := λt s, s.uniformity ≤ t.uniformity,
le_antisymm := assume t s h₁ h₂, uniform_space_eq $ le_antisymm h₂ h₁,
le_refl := assume t, le_refl _,
le_trans := assume a b c h₁ h₂, @le_trans _ _ c.uniformity b.uniformity a.uniformity h₂ h₁ }
instance : has_Sup (uniform_space α) :=
⟨assume s, uniform_space.of_core { uniform_space.core .
uniformity := (⨅u∈s, @uniformity α u),
refl := le_infi $ assume u, le_infi $ assume hu, u.refl,
symm := le_infi $ assume u, le_infi $ assume hu,
le_trans (map_mono $ infi_le_of_le _ $ infi_le _ hu) u.symm,
comp := le_infi $ assume u, le_infi $ assume hu,
le_trans (lift'_mono (infi_le_of_le _ $ infi_le _ hu) $ le_refl _) u.comp }⟩
private lemma le_Sup {tt : set (uniform_space α)} {t : uniform_space α} (h : t ∈ tt) :
t ≤ Sup tt :=
show (⨅u∈tt, @uniformity α u) ≤ t.uniformity,
from infi_le_of_le t $ infi_le _ h
private lemma Sup_le {tt : set (uniform_space α)} {t : uniform_space α} (h : ∀t'∈tt, t' ≤ t) :
Sup tt ≤ t :=
show t.uniformity ≤ (⨅u∈tt, @uniformity α u),
from le_infi $ assume t', le_infi $ assume ht', h t' ht'
instance : has_bot (uniform_space α) :=
⟨uniform_space.of_core { uniformity := ⊤, refl := le_top, symm := le_top, comp := le_top }⟩
instance : has_top (uniform_space α) :=
⟨{ to_topological_space := ⊤,
uniformity := principal id_rel,
refl := le_refl _,
symm := by simp [tendsto]; apply subset.refl,
comp :=
begin
rw [lift'_principal],
{ simp, apply subset.refl },
exact monotone_comp_rel monotone_id monotone_id
end,
is_open_uniformity :=
by rw [topological_space.lattice.has_top]; simp [subset_def, id_rel] {contextual := tt }
}⟩
instance : complete_lattice (uniform_space α) :=
{ uniform_space.partial_order with
sup := λa b, Sup {a, b},
le_sup_left := assume a b, le_Sup $ by simp,
le_sup_right := assume a b, le_Sup $ by simp,
sup_le := assume a b c h₁ h₂, Sup_le $ assume t',
begin simp, intro h, cases h with h h, repeat { subst h; assumption } end,
inf := λa b, Sup {x | x ≤ a ∧ x ≤ b},
le_inf := assume a b c h₁ h₂, le_Sup ⟨h₁, h₂⟩,
inf_le_left := assume a b, Sup_le $ assume x ⟨ha, hb⟩, ha,
inf_le_right := assume a b, Sup_le $ assume x ⟨ha, hb⟩, hb,
top := ⊤,
le_top := assume u, u.refl,
bot := ⊥,
bot_le := assume a, show a.uniformity ≤ ⊤, from le_top,
Sup := Sup,
le_Sup := assume s u, le_Sup,
Sup_le := assume s u, Sup_le,
Inf := λtt, Sup {t | ∀t'∈tt, t ≤ t'},
le_Inf := assume s a hs, le_Sup hs,
Inf_le := assume s a ha, Sup_le $ assume u hs, hs _ ha }
lemma supr_uniformity {ι : Sort*} {u : ι → uniform_space α} :
(supr u).uniformity = (⨅i, (u i).uniformity) :=
show (⨅a (h : ∃i:ι, a = u i), a.uniformity) = _, from
le_antisymm
(le_infi $ assume i, infi_le_of_le (u i) $ infi_le _ ⟨i, rfl⟩)
(le_infi $ assume a, le_infi $ assume ⟨i, (ha : a = u i)⟩, ha.symm ▸ infi_le _ _)
lemma sup_uniformity {u v : uniform_space α} :
(u ⊔ v).uniformity = u.uniformity ⊓ v.uniformity :=
have (u ⊔ v) = (⨆i (h : i = u ∨ i = v), i), by simp [supr_or, supr_sup_eq],
calc (u ⊔ v).uniformity = ((⨆i (h : i = u ∨ i = v), i) : uniform_space α).uniformity : by rw [this]
... = _ : by simp [supr_uniformity, infi_or, infi_inf_eq]
instance inhabited_uniform_space : inhabited (uniform_space α) := ⟨⊤⟩
def uniform_space.vmap (f : α → β) (u : uniform_space β) : uniform_space α :=
{ uniformity := u.uniformity.vmap (λp:α×α, (f p.1, f p.2)),
to_topological_space := u.to_topological_space.induced f,
refl := le_trans (by simp; exact assume ⟨a, b⟩ (h : a = b), h ▸ rfl) (vmap_mono u.refl),
symm := tendsto_vmap' $ by simp [prod.swap, (∘)]; exact tendsto_compose tendsto_vmap tendsto_swap_uniformity,
comp := le_trans
begin
rw [vmap_lift'_eq, vmap_lift'_eq2],
exact (lift'_mono' $ assume s hs ⟨a₁, a₂⟩ ⟨x, h₁, h₂⟩, ⟨f x, h₁, h₂⟩),
repeat { exact monotone_comp_rel monotone_id monotone_id }
end
(vmap_mono u.comp),
is_open_uniformity :=
begin
intro s,
change (@is_open α (u.to_topological_space.induced f) s ↔ _),
simp [is_open_iff_nhds, nhds_induced_eq_vmap, mem_nhds_uniformity_iff, filter.vmap],
exact (ball_congr $ assume x hx,
⟨assume ⟨t, hts, ht⟩, ⟨_, ht, assume ⟨x₁, x₂⟩, by simp [*, subset_def] at * {contextual := tt} ⟩,
assume ⟨t, ht, hts⟩, ⟨{y:β | (f x, y) ∈ t},
assume y (hy : (f x, f y) ∈ t), @hts (x, y) hy rfl,
mem_nhds_uniformity_iff.mp $ mem_nhds_left ht⟩⟩)
end }
lemma uniform_continuous_vmap {f : α → β} [u : uniform_space β] :
@uniform_continuous α β (uniform_space.vmap f u) u f :=
tendsto_vmap
theorem to_topological_space_vmap {f : α → β} {u : uniform_space β} :
@uniform_space.to_topological_space _ (uniform_space.vmap f u) =
topological_space.induced f (@uniform_space.to_topological_space β u) :=
eq_of_nhds_eq_nhds $ assume a,
begin
simp [nhds_induced_eq_vmap, nhds_eq_uniformity, nhds_eq_uniformity],
change vmap f (uniformity.lift' (preimage (λb, (f a, b)))) =
(u.uniformity.vmap (λp:α×α, (f p.1, f p.2))).lift' (preimage (λa', (a, a'))),
rw [vmap_lift'_eq monotone_preimage, vmap_lift'_eq2 monotone_preimage],
exact rfl
end
lemma uniform_continuous_vmap' {f : γ → β} {g : α → γ} [v : uniform_space β] [u : uniform_space α]
(h : uniform_continuous (f ∘ g)) : @uniform_continuous α γ u (uniform_space.vmap f v) g :=
tendsto_vmap' h
lemma to_topological_space_mono {u₁ u₂ : uniform_space α} (h : u₁ ≤ u₂) :
@uniform_space.to_topological_space _ u₁ ≤ @uniform_space.to_topological_space _ u₂ :=
le_of_nhds_le_nhds $ assume a,
by rw [@nhds_eq_uniformity α u₁ a, @nhds_eq_uniformity α u₂ a]; exact (lift'_mono h $ le_refl _)
lemma to_topological_space_top : @uniform_space.to_topological_space α ⊤ = ⊤ := rfl
lemma to_topological_space_bot : @uniform_space.to_topological_space α ⊥ = ⊥ :=
bot_unique $ assume s hs, classical.by_cases
(assume : s = ∅, this.symm ▸ @is_open_empty _ ⊥)
(assume : s ≠ ∅,
let ⟨x, hx⟩ := exists_mem_of_ne_empty this in
have univ ⊆ _,
from hs x hx,
have s = univ,
from top_unique $ assume y hy, @this (x, y) ⟨⟩ rfl,
this.symm ▸ @is_open_univ _ ⊥)
lemma to_topological_space_supr {ι : Sort*} {u : ι → uniform_space α} :
@uniform_space.to_topological_space α (supr u) = (⨆i, @uniform_space.to_topological_space α (u i)) :=
classical.by_cases
(assume h : nonempty ι,
eq_of_nhds_eq_nhds $ assume a,
begin
rw [nhds_supr, nhds_eq_uniformity],
change _ = (supr u).uniformity.lift' (preimage $ prod.mk a),
begin
rw [supr_uniformity, lift'_infi],
exact (congr_arg _ $ funext $ assume i, @nhds_eq_uniformity α (u i) a),
exact h,
exact assume a b, rfl
end
end)
(assume : ¬ nonempty ι,
le_antisymm
(have supr u = ⊥, from bot_unique $ supr_le $ assume i, (this ⟨i⟩).elim,
have @uniform_space.to_topological_space _ (supr u) = ⊥,
from this.symm ▸ to_topological_space_bot,
this.symm ▸ bot_le)
(supr_le $ assume i, to_topological_space_mono $ le_supr _ _))
lemma to_topological_space_Sup {s : set (uniform_space α)} :
@uniform_space.to_topological_space α (Sup s) = (⨆i∈s, @uniform_space.to_topological_space α i) :=
begin
rw [Sup_eq_supr, to_topological_space_supr],
apply congr rfl,
apply funext,
intro x,
exact to_topological_space_supr
end
lemma to_topological_space_sup {u v : uniform_space α} :
@uniform_space.to_topological_space α (u ⊔ v) =
@uniform_space.to_topological_space α u ⊔ @uniform_space.to_topological_space α v :=
ord_continuous_sup $ assume s, to_topological_space_Sup
instance : uniform_space empty := ⊤
instance : uniform_space unit := ⊤
instance : uniform_space bool := ⊤
instance : uniform_space ℕ := ⊤
instance : uniform_space ℤ := ⊤
instance {p : α → Prop} [t : uniform_space α] : uniform_space (subtype p) :=
uniform_space.vmap subtype.val t
lemma uniformity_subtype {p : α → Prop} [t : uniform_space α] :
(@uniformity (subtype p) _) = vmap (λq:subtype p × subtype p, (q.1.1, q.2.1)) uniformity :=
rfl
lemma uniform_continuous_subtype_val {p : α → Prop} [uniform_space α] :
uniform_continuous (subtype.val : {a : α // p a} → α) :=
uniform_continuous_vmap
lemma uniform_continuous_subtype_mk {p : α → Prop} [uniform_space α] [uniform_space β]
{f : β → α} (hf : uniform_continuous f) (h : ∀x, p (f x)) :
uniform_continuous (λx, ⟨f x, h x⟩ : β → subtype p) :=
uniform_continuous_vmap' hf
instance [u₁ : uniform_space α] [u₂ : uniform_space β] : uniform_space (α × β) :=
uniform_space.of_core_eq
(u₁.vmap prod.fst ⊔ u₂.vmap prod.snd).to_core
prod.topological_space
(calc prod.topological_space = (u₁.vmap prod.fst ⊔ u₂.vmap prod.snd).to_topological_space :
by rw [to_topological_space_sup, to_topological_space_vmap, to_topological_space_vmap]; refl
... = _ : by rw [uniform_space.to_core_to_topological_space])
lemma uniform_embedding_subtype_emb {α : Type*} {β : Type*} [uniform_space α] [uniform_space β]
(p : α → Prop) {e : α → β} (ue : uniform_embedding e) (de : dense_embedding e) :
uniform_embedding (de.subtype_emb p) :=
⟨(de.subtype p).inj,
by simp [vmap_vmap_comp, (∘), dense_embedding.subtype_emb, uniformity_subtype, ue.right.symm]⟩
lemma uniform_extend_subtype {α : Type*} {β : Type*} {γ : Type*}
[uniform_space α] [uniform_space β] [uniform_space γ] [complete_space γ]
[inhabited γ] [separated γ]
{p : α → Prop} {e : α → β} {f : α → γ} {b : β} {s : set α}
(hf : uniform_continuous (λx:subtype p, f x.val))
(he : uniform_embedding e) (hd : ∀x:β, x ∈ closure (e '' univ))
(hb : closure (e '' s) ∈ (nhds b).sets) (hs : is_closed s) (hp : ∀x∈s, p x) :
∃c, tendsto f (vmap e (nhds b)) (nhds c) :=
have de : dense_embedding e,
from dense_embedding_of_uniform_embedding he hd,
have de' : dense_embedding (de.subtype_emb p),
by exact de.subtype p,
have ue' : uniform_embedding (de.subtype_emb p),
from uniform_embedding_subtype_emb _ he de,
have b ∈ closure (e '' {x | p x}),
from (closure_mono $ mono_image $ hp) (mem_of_nhds hb),
let ⟨c, (hc : tendsto (f ∘ subtype.val) (vmap (de.subtype_emb p) (nhds ⟨b, this⟩)) (nhds c))⟩ :=
uniformly_extend_exists ue' de'.dense hf in
begin
rw [nhds_subtype_eq_vmap] at hc,
simp [vmap_vmap_comp] at hc,
change (tendsto (f ∘ @subtype.val α p) (vmap (e ∘ @subtype.val α p) (nhds b)) (nhds c)) at hc,
rw [←vmap_vmap_comp] at hc,
existsi c,
apply tendsto_vmap'' s _ _ hc,
exact ⟨_, hb, assume x,
begin
change e x ∈ (closure (e '' s)) → x ∈ s,
rw [←closure_induced, closure_eq_nhds],
dsimp,
rw [nhds_induced_eq_vmap, de.induced],
change x ∈ {x | nhds x ⊓ principal s ≠ ⊥} → x ∈ s,
rw [←closure_eq_nhds, closure_eq_of_is_closed hs],
exact id,
exact de.inj
end⟩,
exact (assume x hx, ⟨⟨x, hp x hx⟩, rfl⟩)
end
/- a similar product space is possible on the function space (uniformity of pointwise convergence),
but we want to have the uniformity of uniform convergence on function spaces -/
lemma uniformity_prod [uniform_space α] [uniform_space β] :
@uniformity (α×β) _ =
vmap (λp:(α×β)×(α×β), (p.1.1, p.2.1)) uniformity ⊓
vmap (λp:(α×β)×(α×β), (p.1.2, p.2.2)) uniformity :=
by rw [prod.uniform_space, uniform_space.of_core_eq_to_core, uniformity, sup_uniformity]; refl
lemma uniformity_prod_eq_prod [uniform_space α] [uniform_space β] :
@uniformity (α×β) _ =
map (λp:(α×α)×(β×β), ((p.1.1, p.2.1), (p.1.2, p.2.2))) (filter.prod uniformity uniformity) :=
have map (λp:(α×α)×(β×β), ((p.1.1, p.2.1), (p.1.2, p.2.2))) =
vmap (λp:(α×β)×(α×β), ((p.1.1, p.2.1), (p.1.2, p.2.2))),
from funext $ assume f, map_eq_vmap_of_inverse
(funext $ assume ⟨⟨_, _⟩, ⟨_, _⟩⟩, rfl) (funext $ assume ⟨⟨_, _⟩, ⟨_, _⟩⟩, rfl),
by rw [this, uniformity_prod, prod_def, vmap_inf, vmap_vmap_comp, vmap_vmap_comp]
lemma mem_uniform_prod [t₁ : uniform_space α] [t₂ : uniform_space β] {a : set (α × α)} {b : set (β × β)}
(ha : a ∈ (@uniformity α _).sets) (hb : b ∈ (@uniformity β _).sets) :
{p:(α×β)×(α×β) | (p.1.1, p.2.1) ∈ a ∧ (p.1.2, p.2.2) ∈ b } ∈ (@uniformity (α × β) _).sets :=
by rw [uniformity_prod]; exact inter_mem_inf_sets (preimage_mem_vmap ha) (preimage_mem_vmap hb)
lemma tendsto_prod_uniformity_fst [uniform_space α] [uniform_space β] :
tendsto (λp:(α×β)×(α×β), (p.1.1, p.2.1)) uniformity uniformity :=
le_trans (map_mono (@le_sup_left (uniform_space (α×β)) _ _ _)) map_vmap_le
lemma tendsto_prod_uniformity_snd [uniform_space α] [uniform_space β] :
tendsto (λp:(α×β)×(α×β), (p.1.2, p.2.2)) uniformity uniformity :=
le_trans (map_mono (@le_sup_right (uniform_space (α×β)) _ _ _)) map_vmap_le
lemma uniform_continuous_fst [uniform_space α] [uniform_space β] : uniform_continuous (λp:α×β, p.1) :=
tendsto_prod_uniformity_fst
lemma uniform_continuous_snd [uniform_space α] [uniform_space β] : uniform_continuous (λp:α×β, p.2) :=
tendsto_prod_uniformity_snd
lemma uniform_continuous_prod_mk [uniform_space α] [uniform_space β] [uniform_space γ]
{f₁ : α → β} {f₂ : α → γ} (h₁ : uniform_continuous f₁) (h₂ : uniform_continuous f₂) :
uniform_continuous (λa, (f₁ a, f₂ a)) :=
by
rw [uniform_continuous, uniformity_prod];
exact tendsto_inf (tendsto_vmap' h₁) (tendsto_vmap' h₂)
lemma uniform_embedding_prod {α' : Type*} {β' : Type*}
[uniform_space α] [uniform_space β] [uniform_space α'] [uniform_space β']
{e₁ : α → α'} {e₂ : β → β'} (h₁ : uniform_embedding e₁) (h₂ : uniform_embedding e₂) :
uniform_embedding (λp:α×β, (e₁ p.1, e₂ p.2)) :=
⟨assume ⟨a₁, b₁⟩ ⟨a₂, b₂⟩,
by simp [prod.mk.inj_iff]; exact assume eq₁ eq₂, ⟨h₁.left _ _ eq₁, h₂.left _ _ eq₂⟩,
by simp [(∘), uniformity_prod, h₁.right.symm, h₂.right.symm, vmap_inf, vmap_vmap_comp]⟩
lemma to_topological_space_prod [u : uniform_space α] [v : uniform_space β] :
@uniform_space.to_topological_space (α × β) prod.uniform_space =
@prod.topological_space α β u.to_topological_space v.to_topological_space := rfl
lemma to_topological_space_subtype [u : uniform_space α] {p : α → Prop} :
@uniform_space.to_topological_space (subtype p) subtype.uniform_space =
@subtype.topological_space α p u.to_topological_space := rfl
end constructions
|
b956bb1271516e1143e2cfffabd0dbe823e36fed | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/1343.lean | ba16866aafaa45941da87d446dcbaefb55c4d992 | [
"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 | 290 | lean | universe variable u
namespace ex1
inductive foo (α : Type (u+1)) : Type (u+1)
| mk : α → foo
inductive bug
| leaf : bug
| mk : foo bug → bug
end ex1
namespace ex2
inductive foo (α : Type u) : Type u
| mk : α → foo
inductive bug
| leaf : bug
| mk : foo bug → bug
end ex2
|
4091760f41e8e98ad6e248b44a17599b9a550f41 | a45212b1526d532e6e83c44ddca6a05795113ddc | /src/order/filter/filter_product.lean | 2c8fc47977b60862e15b7c7caf62bd2784deced1 | [
"Apache-2.0"
] | permissive | fpvandoorn/mathlib | b21ab4068db079cbb8590b58fda9cc4bc1f35df4 | b3433a51ea8bc07c4159c1073838fc0ee9b8f227 | refs/heads/master | 1,624,791,089,608 | 1,556,715,231,000 | 1,556,715,231,000 | 165,722,980 | 5 | 0 | Apache-2.0 | 1,552,657,455,000 | 1,547,494,646,000 | Lean | UTF-8 | Lean | false | false | 16,808 | lean | /-
Copyright (c) 2019 Abhimanyu Pallavi Sudhir. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Abhimanyu Pallavi Sudhir
"Filterproducts" (ultraproducts on general filters), ultraproducts.
-/
import order.filter.basic
universes u v
variables {α : Type u} (β : Type v) (φ : filter α)
local attribute [instance] classical.prop_decidable
namespace filter
/-- Two sequences are bigly equal iff the kernel of their difference is in φ -/
def bigly_equal : setoid (α → β) :=
⟨ λ a b, {n | a n = b n} ∈ φ,
λ a, by simp only [eq_self_iff_true, (set.univ_def).symm, univ_sets],
λ a b ab, by simpa only [eq_comm],
λ a b c ab bc, sets_of_superset φ (inter_sets φ ab bc) (λ n r, eq.trans r.1 r.2)⟩
/-- Ultraproduct, but on a general filter -/
def filterprod := quotient (bigly_equal β φ)
local notation `β*` := filterprod β φ
namespace filter_product
variables {α β φ} include φ
def of_seq : (α → β) → β* := @quotient.mk' (α → β) (bigly_equal β φ)
/-- Equivalence class containing the constant sequence of a term in β -/
def of (b : β): β* := of_seq (function.const α b)
/-- Lift function to filter product -/
def lift (f : β → β) : β* → β* :=
λ x, quotient.lift_on' x (λ a, (of_seq $ λ n, f (a n) : β*)) $
λ a b h, quotient.sound' $ show _ ∈ _, by filter_upwards [h] λ i hi, congr_arg _ hi
/-- Lift binary operation to filter product -/
def lift₂ (f : β → β → β) : β* → β* → β* :=
λ x y, quotient.lift_on₂' x y (λ a b, (of_seq $ λ n, f (a n) (b n) : β*)) $
λ a₁ a₂ b₁ b₂ h1 h2, quotient.sound' $ show _ ∈ _,
by filter_upwards [h1, h2] λ i hi1 hi2, congr (congr_arg _ hi1) hi2
/-- Lift properties to filter product -/
def lift_rel (R : β → Prop) : β* → Prop :=
λ x, quotient.lift_on' x (λ a, {i : α | R (a i)} ∈ φ) $ λ a b h, propext
⟨ λ ha, by filter_upwards [h, ha] λ i hi hia, by simpa [hi.symm],
λ hb, by filter_upwards [h, hb] λ i hi hib, by simpa [hi.symm.symm] ⟩
/-- Lift binary relations to filter product -/
def lift_rel₂ (R : β → β → Prop) : β* → β* → Prop :=
λ x y, quotient.lift_on₂' x y (λ a b, {i : α | R (a i) (b i)} ∈ φ) $
λ a₁ a₂ b₁ b₂ h₁ h₂, propext
⟨ λ ha, by filter_upwards [h₁, h₂, ha] λ i hi1 hi2 hia, by simpa [hi1.symm, hi2.symm],
λ hb, by filter_upwards [h₁, h₂, hb] λ i hi1 hi2 hib, by simpa [hi1.symm.symm, hi2.symm.symm] ⟩
instance coe_filterprod : has_coe β β* := ⟨ of ⟩
instance [has_add β] : has_add β* := { add := lift₂ has_add.add }
instance [has_zero β] : has_zero β* := { zero := of 0 }
instance [has_neg β] : has_neg β* :=
{ neg := lift has_neg.neg }
instance [add_semigroup β] : add_semigroup β* :=
{ add_assoc := λ x y z, quotient.induction_on₃' x y z $ λ a b c, quotient.sound' $
show {n | _ + _ + _ = _ + (_ + _)} ∈ _, by simp only [add_assoc, eq_self_iff_true]; exact φ.univ_sets,
..filter_product.has_add }
instance [add_monoid β] : add_monoid β* :=
{ zero_add := λ x, quotient.induction_on' x
(λ a, quotient.sound'(by simp only [zero_add]; apply (setoid.iseqv _).1)),
add_zero := λ x, quotient.induction_on' x
(λ a, quotient.sound'(by simp only [add_zero]; apply (setoid.iseqv _).1)),
..filter_product.add_semigroup,
..filter_product.has_zero }
instance [add_comm_semigroup β] : add_comm_semigroup β* :=
{ add_comm := λ x y, quotient.induction_on₂' x y
(λ a b, quotient.sound' (by simp only [add_comm]; apply (setoid.iseqv _).1)),
..filter_product.add_semigroup }
instance [add_comm_monoid β] : add_comm_monoid β* :=
{ ..filter_product.add_comm_semigroup,
..filter_product.add_monoid }
instance [add_group β] : add_group β* :=
{ add_left_neg := λ x, quotient.induction_on' x
(λ a, quotient.sound' (by simp only [add_left_neg]; apply (setoid.iseqv _).1)),
..filter_product.add_monoid,
..filter_product.has_neg }
instance [add_comm_group β] : add_comm_group β* :=
{ ..filter_product.add_comm_monoid,
..filter_product.add_group }
instance [has_mul β] : has_mul β* :=
{ mul := lift₂ has_mul.mul }
instance [has_one β] : has_one β* := { one := of 1 }
instance [has_inv β] : has_inv β* :=
{ inv := lift has_inv.inv }
instance [semigroup β] : semigroup β* :=
{ mul_assoc := λ x y z, quotient.induction_on₃' x y z $ λ a b c, quotient.sound' $
show {n | _ * _ * _ = _ * (_ * _)} ∈ _, by simp only [mul_assoc, eq_self_iff_true]; exact φ.2,
..filter_product.has_mul }
instance [monoid β] : monoid β* :=
{ one_mul := λ x, quotient.induction_on' x
(λ a, quotient.sound' (by simp only [one_mul]; apply (setoid.iseqv _).1)),
mul_one := λ x, quotient.induction_on' x
(λ a, quotient.sound' (by simp only [mul_one]; apply (setoid.iseqv _).1)),
..filter_product.semigroup,
..filter_product.has_one }
instance [comm_semigroup β] : comm_semigroup β* :=
{ mul_comm := λ x y, quotient.induction_on₂' x y
(λ a b, quotient.sound' (by simp only [mul_comm]; apply (setoid.iseqv _).1)),
..filter_product.semigroup }
instance [comm_monoid β] : comm_monoid β* :=
{ ..filter_product.comm_semigroup,
..filter_product.monoid }
instance [group β] : group β* :=
{ mul_left_inv := λ x, quotient.induction_on' x
(λ a, quotient.sound' (by simp only [mul_left_inv]; apply (setoid.iseqv _).1)),
..filter_product.monoid,
..filter_product.has_inv }
instance [comm_group β] : comm_group β* :=
{ ..filter_product.comm_monoid,
..filter_product.group }
instance [distrib β] : distrib β* :=
{ left_distrib := λ x y z, quotient.induction_on₃' x y z
(λ x y z, quotient.sound' (by simp only [left_distrib]; apply (setoid.iseqv _).1)),
right_distrib := λ x y z, quotient.induction_on₃' x y z
(λ x y z, quotient.sound' (by simp only [right_distrib]; apply (setoid.iseqv _).1)),
..filter_product.has_add,
..filter_product.has_mul }
instance [mul_zero_class β] : mul_zero_class β* :=
{ zero_mul := λ x, quotient.induction_on' x
(λ a, quotient.sound' (by simp only [zero_mul]; apply (setoid.iseqv _).1)),
mul_zero := λ x, quotient.induction_on' x
(λ a, quotient.sound' (by simp only [mul_zero]; apply (setoid.iseqv _).1)),
..filter_product.has_mul,
..filter_product.has_zero }
instance [semiring β] : semiring β* :=
{ ..filter_product.add_comm_monoid,
..filter_product.monoid,
..filter_product.distrib,
..filter_product.mul_zero_class }
instance [ring β] : ring β* :=
{ ..filter_product.add_comm_group,
..filter_product.monoid,
..filter_product.distrib }
instance [comm_semiring β] : comm_semiring β* :=
{ ..filter_product.semiring,
..filter_product.comm_monoid }
instance [comm_ring β] : comm_ring β* :=
{ ..filter_product.ring,
..filter_product.comm_semigroup }
instance [zero_ne_one_class β] (NT : φ ≠ ⊥) : zero_ne_one_class β* :=
{ zero_ne_one := λ c, have c' : _ := quotient.exact' c, by
{ change _ ∈ _ at c',
simp only [set.set_of_false, zero_ne_one, empty_in_sets_eq_bot] at c',
exact NT c' },
..filter_product.has_zero,
..filter_product.has_one }
instance [division_ring β] (U : is_ultrafilter φ) : division_ring β* :=
{ mul_inv_cancel := λ x, quotient.induction_on' x $ λ a hx, quotient.sound' $
have hx1 : _ := (not_imp_not.mpr quotient.eq'.mpr) hx,
have hx2 : _ := (ultrafilter_iff_compl_mem_iff_not_mem.mp U _).mpr hx1,
have h : {n : α | ¬a n = 0} ⊆ {n : α | a n * (a n)⁻¹ = 1} :=
by rw [set.set_of_subset_set_of]; exact λ n, division_ring.mul_inv_cancel,
mem_sets_of_superset hx2 h,
inv_mul_cancel := λ x, quotient.induction_on' x $ λ a hx, quotient.sound' $
have hx1 : _ := (not_imp_not.mpr quotient.eq'.mpr) hx,
have hx2 : _ := (ultrafilter_iff_compl_mem_iff_not_mem.mp U _).mpr hx1,
have h : {n : α | ¬a n = 0} ⊆ {n : α | (a n)⁻¹ * a n = 1} :=
by rw [set.set_of_subset_set_of]; exact λ n, division_ring.inv_mul_cancel,
mem_sets_of_superset hx2 h,
..filter_product.ring,
..filter_product.has_inv,
..filter_product.zero_ne_one_class U.1 }
instance [field β] (U : is_ultrafilter φ) : field β* :=
{ ..filter_product.comm_ring,
..filter_product.division_ring U }
noncomputable instance [discrete_field β] (U : is_ultrafilter φ) : discrete_field β* :=
{ inv_zero := quotient.sound' $ by show _ ∈ _;
simp only [inv_zero, eq_self_iff_true, (set.univ_def).symm, univ_sets],
has_decidable_eq := by apply_instance,
..filter_product.field U }
instance [has_le β] : has_le β* := { le := lift_rel₂ has_le.le }
instance [preorder β] : preorder β* :=
{ le_refl := λ x, quotient.induction_on' x $ λ a, show _ ∈ _,
by simp only [le_refl, (set.univ_def).symm, univ_sets],
le_trans := λ x y z, quotient.induction_on₃' x y z $ λ a b c hab hbc,
by filter_upwards [hab, hbc] λ i hiab hibc, le_trans hiab hibc,
..filter_product.has_le }
instance [partial_order β] : partial_order β* :=
{ le_antisymm := λ x y, quotient.induction_on₂' x y $ λ a b hab hba, quotient.sound' $
have hI : {n | a n = b n} = _ ∩ _ := set.ext (λ n, le_antisymm_iff),
show _ ∈ _, by rw hI; exact inter_sets _ hab hba
..filter_product.preorder }
instance [linear_order β] (U : is_ultrafilter φ) : linear_order β* :=
{ le_total := λ x y, quotient.induction_on₂' x y $ λ a b,
have hS : _ ⊆ {i | b i ≤ a i} := λ i, le_of_not_le,
or.cases_on (mem_or_compl_mem_of_ultrafilter U {i | a i ≤ b i})
(λ h, or.inl h)
(λ h, or.inr (sets_of_superset _ h hS))
..filter_product.partial_order }
theorem of_inj (NT : φ ≠ ⊥): function.injective (@of _ β φ) :=
begin
intros r s rs, by_contra N,
rw [of, of, of_seq, quotient.eq', bigly_equal] at rs,
simp only [N, set.set_of_false, empty_in_sets_eq_bot] at rs,
exact NT rs
end
theorem of_seq_fun (f g : α → β) (h : β → β) (H : {n : α | f n = h (g n) } ∈ φ) :
of_seq f = (lift h) (@of_seq _ _ φ g) := quotient.sound' H
theorem of_seq_fun₂ (f g₁ g₂ : α → β) (h : β → β → β) (H : {n : α | f n = h (g₁ n) (g₂ n) } ∈ φ) :
of_seq f = (lift₂ h) (@of_seq _ _ φ g₁) (@of_seq _ _ φ g₂) := quotient.sound' H
@[simp] lemma of_seq_zero [has_zero β] (f : α → β) : of_seq 0 = (0 : β*) := rfl
@[simp] lemma of_seq_add [has_add β] (f g : α → β) : of_seq (f + g) = of_seq f + (of_seq g : β*) := rfl
@[simp] lemma of_seq_neg [has_neg β] (f : α → β) : of_seq (-f) = - (of_seq f : β*) := rfl
@[simp] lemma of_seq_one [has_one β] (f : α → β) : of_seq 1 = (1 : β*) := rfl
@[simp] lemma of_seq_mul [has_mul β] (f g : α → β) : of_seq (f * g) = of_seq f * (of_seq g : β*) := rfl
@[simp] lemma of_seq_inv [has_inv β] (f : α → β) : of_seq (f⁻¹) = (of_seq f : β*)⁻¹ := rfl
lemma of_eq_coe (x : β) : of x = (↑x : β*) := rfl
@[simp] lemma of_id (x : β) : of x = (x : β*) := rfl
lemma of_eq (x y : β) (NT : φ ≠ ⊥) : x = y ↔ of x = (of y : β*) := ⟨λ h, by rw h, by apply of_inj NT⟩
lemma of_ne (x y : β) (NT : φ ≠ ⊥) : x ≠ y ↔ of x ≠ (of y : β*) := by show ¬ x = y ↔ of x ≠ of y; rwa [of_eq]
lemma of_eq_zero [has_zero β] (NT : φ ≠ ⊥) (x : β) : x = 0 ↔ of x = (0 : β*) := of_eq _ _ NT
lemma of_ne_zero [has_zero β] (NT : φ ≠ ⊥) (x : β) : x ≠ 0 ↔ of x ≠ (0 : β*) := of_ne _ _ NT
@[simp] lemma of_zero [has_zero β] : of 0 = (0 : β*) := rfl
@[simp] lemma of_add [has_add β] (x y : β) : of (x + y) = of x + (of y : β*) := rfl
@[simp] lemma of_neg [has_neg β] (x : β) : of (- x) = - (of x : β*) := rfl
@[simp] lemma of_one [has_one β] : of 1 = (1 : β*) := rfl
@[simp] lemma of_mul [has_mul β] (x y : β) : of (x * y) = of x * (of y : β*) := rfl
@[simp] lemma of_inv [has_inv β] (x : β) : of (x⁻¹) = (of x : β*)⁻¹ := rfl
lemma of_rel_of_rel (R : β → Prop) (x : β) :
R x → (lift_rel R) (of x : β*) :=
λ hx, by show {i | R x} ∈ _; simp only [hx]; exact univ_mem_sets
lemma of_rel (R : β → Prop) (x : β) (NT: φ ≠ ⊥) :
R x ↔ (lift_rel R) (of x : β*) :=
⟨ of_rel_of_rel _ _,
λ hxy, by change {i | R x} ∈ _ at hxy; by_contra h;
simp only [h, set.set_of_false, empty_in_sets_eq_bot] at hxy;
exact NT hxy ⟩
lemma of_rel_of_rel₂ (R : β → β → Prop) (x y : β) :
R x y → (lift_rel₂ R) (of x) (of y : β*) :=
λ hxy, by show {i | R x y} ∈ _; simp only [hxy]; exact univ_mem_sets
lemma of_rel₂ (R : β → β → Prop) (x y : β) (NT: φ ≠ ⊥) :
R x y ↔ (lift_rel₂ R) (of x) (of y : β*) :=
⟨ of_rel_of_rel₂ _ _ _,
λ hxy, by change {i | R x y} ∈ _ at hxy; by_contra h;
simp only [h, set.set_of_false, empty_in_sets_eq_bot] at hxy;
exact NT hxy ⟩
lemma of_le_of_le [has_le β] (x y : β) : x ≤ y → of x ≤ (of y : β*) := of_rel_of_rel₂ _ _ _
lemma of_le [has_le β] (x y : β) (NT: φ ≠ ⊥) : x ≤ y ↔ of x ≤ (of y : β*) := of_rel₂ _ _ _ NT
lemma lt_def [K : preorder β] (U : is_ultrafilter φ) (x y : β*) :
(x < y) ↔ @lift_rel₂ _ _ φ K.lt x y :=
⟨ quotient.induction_on₂' x y $ λ a b ⟨hxy, hyx⟩,
have hyx' : _ := (ultrafilter_iff_compl_mem_iff_not_mem.mp U _).mpr hyx,
by filter_upwards [hxy, hyx'] λ i hi1 hi2, lt_iff_le_not_le.mpr ⟨hi1, hi2⟩,
quotient.induction_on₂' x y $ λ a b hab,
⟨ by filter_upwards [hab] λ i, le_of_lt, λ hba,
have hc : ∀ i : α, a i < b i ∧ b i ≤ a i → false := λ i ⟨h1, h2⟩, not_lt_of_le h2 h1,
have h0 : ∅ = {i : α | a i < b i} ∩ {i : α | b i ≤ a i} :=
by simp only [set.inter_def, hc, set.set_of_false, eq_self_iff_true, set.mem_set_of_eq],
U.1 $ empty_in_sets_eq_bot.mp $ by rw [h0]; exact inter_sets _ hab hba ⟩ ⟩
lemma lt_def' [K : preorder β] (U : is_ultrafilter φ) :
filter_product.preorder.lt = @lift_rel₂ _ _ φ K.lt :=
by ext x y; exact lt_def U x y
lemma of_lt_of_lt [preorder β] (U : is_ultrafilter φ) (x y : β) :
x < y → of x < (of y : β*) :=
by rw lt_def U; apply of_rel_of_rel₂
lemma of_lt [preorder β] (x y : β) (U : is_ultrafilter φ) : x < y ↔ of x < (of y : β*) :=
by rw lt_def U; exact of_rel₂ _ _ _ U.1
instance [ordered_comm_group β] (U : is_ultrafilter φ) : ordered_comm_group β* :=
{ add_le_add_left := λ x y hxy z, by revert hxy; exact quotient.induction_on₃' x y z
(λ a b c hab, by filter_upwards [hab] λ i hi, by simpa),
add_lt_add_left := λ x y hxy z, by revert hxy; exact quotient.induction_on₃' x y z
(λ a b c hab, by rw lt_def U at hab ⊢; filter_upwards [hab] λ i hi, add_lt_add_left hi (c i)),
..filter_product.partial_order, ..filter_product.add_comm_group }
instance [ordered_ring β] (U : is_ultrafilter φ) : ordered_ring β* :=
{ mul_nonneg := λ x y, quotient.induction_on₂' x y $
λ a b ha hb, by filter_upwards [ha, hb] λ i, by simp only [set.mem_set_of_eq]; exact mul_nonneg,
mul_pos := λ x y, quotient.induction_on₂' x y $
λ a b ha hb, by rw lt_def U at ha hb ⊢; filter_upwards [ha, hb] λ i, mul_pos,
..filter_product.ring, ..filter_product.ordered_comm_group U, ..filter_product.zero_ne_one_class U.1 }
instance [linear_ordered_ring β] (U : is_ultrafilter φ) : linear_ordered_ring β* :=
{ zero_lt_one := by rw lt_def U; show {i | (0 : β) < 1} ∈ _; simp only [zero_lt_one, (set.univ_def).symm, univ_sets],
..filter_product.ordered_ring U, ..filter_product.linear_order U }
instance [linear_ordered_field β] (U : is_ultrafilter φ) : linear_ordered_field β* :=
{ ..filter_product.linear_ordered_ring U, ..filter_product.field U }
instance [linear_ordered_comm_ring β] (U : is_ultrafilter φ) : linear_ordered_comm_ring β* :=
{ ..filter_product.linear_ordered_ring U, ..filter_product.comm_monoid }
noncomputable instance [decidable_linear_order β] (U : is_ultrafilter φ) : decidable_linear_order β* :=
{ decidable_le := by apply_instance,
..filter_product.linear_order U }
noncomputable instance [decidable_linear_ordered_comm_group β] (U : is_ultrafilter φ) : decidable_linear_ordered_comm_group β* :=
{ ..filter_product.ordered_comm_group U, ..filter_product.decidable_linear_order U }
noncomputable instance [decidable_linear_ordered_comm_ring β] (U : is_ultrafilter φ) : decidable_linear_ordered_comm_ring β* :=
{ ..filter_product.linear_ordered_comm_ring U, ..filter_product.decidable_linear_ordered_comm_group U }
noncomputable instance [discrete_linear_ordered_field β] (U : is_ultrafilter φ) : discrete_linear_ordered_field β* :=
{ ..filter_product.linear_ordered_field U, ..filter_product.decidable_linear_ordered_comm_ring U, ..filter_product.discrete_field U }
end filter_product
end filter
|
0f9c4643a2e45769342fa6295bff3388f4561b05 | 54ce0561cebde424526f41d45f490ed56be2bd0c | /src/game/ch4_Integers_and_Rationals/2_The_Rationals.lean | 078e07ca72858d6b925a283b6ac85862274fee03 | [] | no_license | melembroucarlitos/Tao_Analysis-LEAN | cf7b3298d317891a09e4bf21cfe7c7ffcb57b9a9 | 3f4fc7e090d96b6cef64896492fba4bef124794b | refs/heads/master | 1,692,952,385,694 | 1,636,287,522,000 | 1,636,287,522,000 | 400,630,166 | 3 | 0 | null | 1,635,910,807,000 | 1,630,096,823,000 | Lean | UTF-8 | Lean | false | false | 170 | lean | -- Level name : The Rational Numbers
/-
# Hey yall
## This is just to a placeholder to make sure all is working
these are some words
and these are some other words
-/
|
f853121e4399b3745397e8a8834c9ae0e4323c0d | 55c7fc2bf55d496ace18cd6f3376e12bb14c8cc5 | /src/data/polynomial/identities.lean | 7149747917e0c8747e74eca6afb3b1bfa3ac97d8 | [
"Apache-2.0"
] | permissive | dupuisf/mathlib | 62de4ec6544bf3b79086afd27b6529acfaf2c1bb | 8582b06b0a5d06c33ee07d0bdf7c646cae22cf36 | refs/heads/master | 1,669,494,854,016 | 1,595,692,409,000 | 1,595,692,409,000 | 272,046,630 | 0 | 0 | Apache-2.0 | 1,592,066,143,000 | 1,592,066,142,000 | null | UTF-8 | Lean | false | false | 3,489 | lean | /-
Copyright (c) 2018 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes, Johannes Hölzl, Scott Morrison, Jens Wagemaker
-/
import data.polynomial.derivative
/-!
# Theory of univariate polynomials
The main def is `binom_expansion`.
-/
noncomputable theory
namespace polynomial
universes u v w x y z
variables {R : Type u} {S : Type v} {T : Type w} {ι : Type x} {k : Type y} {A : Type z}
{a b : R} {m n : ℕ}
section identities
/- @TODO: pow_add_expansion and pow_sub_pow_factor are not specific to polynomials.
These belong somewhere else. But not in group_power because they depend on tactic.ring_exp
Maybe use data.nat.choose to prove it.
-/
def pow_add_expansion {R : Type*} [comm_semiring R] (x y : R) : ∀ (n : ℕ),
{k // (x + y)^n = x^n + n*x^(n-1)*y + k * y^2}
| 0 := ⟨0, by simp⟩
| 1 := ⟨0, by simp⟩
| (n+2) :=
begin
cases pow_add_expansion (n+1) with z hz,
existsi x*z + (n+1)*x^n+z*y,
calc (x + y) ^ (n + 2) = (x + y) * (x + y) ^ (n + 1) : by ring_exp
... = (x + y) * (x ^ (n + 1) + ↑(n + 1) * x ^ (n + 1 - 1) * y + z * y ^ 2) : by rw hz
... = x ^ (n + 2) + ↑(n + 2) * x ^ (n + 1) * y + (x*z + (n+1)*x^n+z*y) * y ^ 2 :
by { push_cast, ring_exp! }
end
variables [comm_ring R]
private def poly_binom_aux1 (x y : R) (e : ℕ) (a : R) :
{k : R // a * (x + y)^e = a * (x^e + e*x^(e-1)*y + k*y^2)} :=
begin
existsi (pow_add_expansion x y e).val,
congr,
apply (pow_add_expansion _ _ _).property
end
private lemma poly_binom_aux2 (f : polynomial R) (x y : R) :
f.eval (x + y) = f.sum (λ e a, a * (x^e + e*x^(e-1)*y + (poly_binom_aux1 x y e a).val*y^2)) :=
begin
unfold eval eval₂, congr, ext,
apply (poly_binom_aux1 x y _ _).property
end
private lemma poly_binom_aux3 (f : polynomial R) (x y : R) : f.eval (x + y) =
f.sum (λ e a, a * x^e) +
f.sum (λ e a, (a * e * x^(e-1)) * y) +
f.sum (λ e a, (a *(poly_binom_aux1 x y e a).val)*y^2) :=
by rw poly_binom_aux2; simp [left_distrib, finsupp.sum_add, mul_assoc]
lemma derivative_eval (p : polynomial R) (x : R) :
p.derivative.eval x = p.sum (λ n a, (a * n)*x^(n-1)) :=
by simp only [derivative, eval_sum, eval_pow, eval_C, eval_X, eval_nat_cast, eval_mul]
def binom_expansion (f : polynomial R) (x y : R) :
{k : R // f.eval (x + y) = f.eval x + (f.derivative.eval x) * y + k * y^2} :=
begin
existsi f.sum (λ e a, a *((poly_binom_aux1 x y e a).val)),
rw poly_binom_aux3,
congr,
{ rw derivative_eval, symmetry,
apply finsupp.sum_mul },
{ symmetry, apply finsupp.sum_mul }
end
def pow_sub_pow_factor (x y : R) : Π (i : ℕ), {z : R // x^i - y^i = z * (x - y)}
| 0 := ⟨0, by simp⟩
| 1 := ⟨1, by simp⟩
| (k+2) :=
begin
cases @pow_sub_pow_factor (k+1) with z hz,
existsi z*x + y^(k+1),
calc x ^ (k + 2) - y ^ (k + 2)
= x * (x ^ (k + 1) - y ^ (k + 1)) + (x * y ^ (k + 1) - y ^ (k + 2)) : by ring_exp
... = x * (z * (x - y)) + (x * y ^ (k + 1) - y ^ (k + 2)) : by rw hz
... = (z * x + y ^ (k + 1)) * (x - y) : by ring_exp
end
def eval_sub_factor (f : polynomial R) (x y : R) :
{z : R // f.eval x - f.eval y = z * (x - y)} :=
begin
refine ⟨f.sum (λ i r, r * (pow_sub_pow_factor x y i).val), _⟩,
delta eval eval₂,
rw ← finsupp.sum_sub,
rw finsupp.sum_mul,
delta finsupp.sum,
congr, ext i r, dsimp,
rw [mul_assoc, ←(pow_sub_pow_factor x y _).prop, mul_sub],
end
end identities
end polynomial
|
d549c61b1b29ea3cc4b18deb6ab7c32befba7819 | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/algebraic_geometry/elliptic_curve/point.lean | f8e6785033fa00d460b9741677d0cb216232568d | [
"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 | 39,400 | lean | /-
Copyright (c) 2022 David Kurniadi Angdinata. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: David Kurniadi Angdinata
-/
import algebraic_geometry.elliptic_curve.weierstrass
import linear_algebra.free_module.norm
import ring_theory.class_group
/-!
# Nonsingular rational points on Weierstrass curves
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
This file defines the type of nonsingular rational points on a Weierstrass curve over a field and
proves that it forms an abelian group under a geometric secant-and-tangent process.
## Mathematical background
Let `W` be a Weierstrass curve over a field `F`. A rational point on `W` is simply a point
$[X:Y:Z]$ defined over `F` in the projective plane satisfying the homogeneous cubic equation
$Y^2Z + a_1XYZ + a_3YZ^2 = X^3 + a_2X^2Z + a_4XZ^2 + a_6Z^3$. Any such point either lies in the
affine chart $Z \ne 0$ and satisfies the Weierstrass equation obtained by replacing $X/Z$ with $X$
and $Y/Z$ with $Y$, or is the unique point at infinity $0 := [0:1:0]$ when $Z = 0$. With this new
description, a nonsingular rational point on `W` is either $0$ or an affine point $(x, y)$ where
the partial derivatives $W_X(X, Y)$ and $W_Y(X, Y)$ do not vanish simultaneously. For a field
extension `K` of `F`, a `K`-rational point is simply a rational point on `W` base changed to `K`.
The set of nonsingular rational points forms an abelian group under a secant-and-tangent process.
* The identity rational point is `0`.
* Given a nonsingular rational point `P`, its negation `-P` is defined to be the unique third
point of intersection between `W` and the line through `0` and `P`.
Explicitly, if `P` is $(x, y)$, then `-P` is $(x, -y - a_1x - a_3)$.
* Given two points `P` and `Q`, their addition `P + Q` is defined to be the negation of the unique
third point of intersection between `W` and the line `L` through `P` and `Q`.
Explicitly, let `P` be $(x_1, y_1)$ and let `Q` be $(x_2, y_2)$.
* If $x_1 = x_2$ and $y_1 = -y_2 - a_1x_2 - a_3$, then `L` is vertical and `P + Q` is `0`.
* If $x_1 = x_2$ and $y_1 \ne -y_2 - a_1x_2 - a_3$, then `L` is the tangent of `W` at `P = Q`,
and has slope $\ell := (3x_1^2 + 2a_2x_1 + a_4 - a_1y_1) / (2y_1 + a_1x_1 + a_3)$.
* Otherwise $x_1 \ne x_2$, then `L` is the secant of `W` through `P` and `Q`, and has slope
$\ell := (y_1 - y_2) / (x_1 - x_2)$.
In the latter two cases, the $X$-coordinate of `P + Q` is then the unique third solution of the
equation obtained by substituting the line $Y = \ell(X - x_1) + y_1$ into the Weierstrass
equation, and can be written down explicitly as $x := \ell^2 + a_1\ell - a_2 - x_1 - x_2$ by
inspecting the $X^2$ terms. The $Y$-coordinate of `P + Q`, after applying the final negation
that maps $Y$ to $-Y - a_1X - a_3$, is precisely $y := -(\ell(x - x_1) + y_1) - a_1x - a_3$.
The group law on this set is then uniquely determined by these constructions.
## Main definitions
* `weierstrass_curve.point`: the type of nonsingular rational points on a Weierstrass curve `W`.
* `weierstrass_curve.point.add`: the addition of two nonsingular rational points on `W`.
## Main statements
* `weierstrass_curve.point.add_comm_group`: the type of nonsingular rational points on `W` forms an
abelian group under addition.
## Notations
* `W⟮K⟯`: the group of nonsingular rational points on `W` base changed to `K`.
## References
[J Silverman, *The Arithmetic of Elliptic Curves*][silverman2009]
## Tags
elliptic curve, rational point, group law
-/
private meta def map_simp : tactic unit :=
`[simp only [map_one, map_bit0, map_bit1, map_neg, map_add, map_sub, _root_.map_mul, map_pow,
map_div₀]]
private meta def eval_simp : tactic unit :=
`[simp only [eval_C, eval_X, eval_neg, eval_add, eval_sub, eval_mul, eval_pow]]
private meta def C_simp : tactic unit :=
`[simp only [C_1, C_bit0, C_bit1, C_neg, C_add, C_sub, C_mul, C_pow]]
private meta def derivative_simp : tactic unit :=
`[simp only [derivative_C, derivative_X, derivative_X_pow, derivative_neg, derivative_add,
derivative_sub, derivative_mul, derivative_sq]]
universes u v w
namespace weierstrass_curve
open coordinate_ring ideal polynomial
open_locale non_zero_divisors polynomial polynomial_polynomial
section basic
/-! ### Polynomials associated to nonsingular rational points on a Weierstrass curve -/
variables {R : Type u} [comm_ring R] (W : weierstrass_curve R) (A : Type v) [comm_ring A]
[algebra R A] (B : Type w) [comm_ring B] [algebra R B] [algebra A B] [is_scalar_tower R A B]
(x₁ x₂ y₁ y₂ L : R)
/-- The polynomial $-Y - a_1X - a_3$ associated to negation. -/
noncomputable def neg_polynomial : R[X][Y] := -Y - C (C W.a₁ * X + C W.a₃)
/-- The $Y$-coordinate of the negation of an affine point in `W`.
This depends on `W`, and has argument order: $x_1$, $y_1$. -/
@[simp] def neg_Y : R := -y₁ - W.a₁ * x₁ - W.a₃
lemma neg_Y_neg_Y : W.neg_Y x₁ (W.neg_Y x₁ y₁) = y₁ := by { simp only [neg_Y], ring1 }
lemma base_change_neg_Y :
(W.base_change A).neg_Y (algebra_map R A x₁) (algebra_map R A y₁)
= algebra_map R A (W.neg_Y x₁ y₁) :=
by { simp only [neg_Y], map_simp, refl }
lemma base_change_neg_Y_of_base_change (x₁ y₁ : A) :
(W.base_change B).neg_Y (algebra_map A B x₁) (algebra_map A B y₁)
= algebra_map A B ((W.base_change A).neg_Y x₁ y₁) :=
by rw [← base_change_neg_Y, base_change_base_change]
@[simp] lemma eval_neg_polynomial : (W.neg_polynomial.eval $ C y₁).eval x₁ = W.neg_Y x₁ y₁ :=
by { rw [neg_Y, sub_sub, neg_polynomial], eval_simp }
/-- The polynomial $L(X - x_1) + y_1$ associated to the line $Y = L(X - x_1) + y_1$,
with a slope of $L$ that passes through an affine point $(x_1, y_1)$.
This does not depend on `W`, and has argument order: $x_1$, $y_1$, $L$. -/
noncomputable def line_polynomial : R[X] := C L * (X - C x₁) + C y₁
lemma XY_ideal_eq₁ : XY_ideal W x₁ (C y₁) = XY_ideal W x₁ (line_polynomial x₁ y₁ L) :=
begin
simp only [XY_ideal, X_class, Y_class, line_polynomial],
rw [← span_pair_add_mul_right $ adjoin_root.mk _ $ C $ C $ -L, ← _root_.map_mul, ← map_add],
apply congr_arg (_ ∘ _ ∘ _ ∘ _),
C_simp,
ring1
end
/-- The polynomial obtained by substituting the line $Y = L*(X - x_1) + y_1$, with a slope of $L$
that passes through an affine point $(x_1, y_1)$, into the polynomial $W(X, Y)$ associated to `W`.
If such a line intersects `W` at another point $(x_2, y_2)$, then the roots of this polynomial are
precisely $x_1$, $x_2$, and the $X$-coordinate of the addition of $(x_1, y_1)$ and $(x_2, y_2)$.
This depends on `W`, and has argument order: $x_1$, $y_1$, $L$. -/
noncomputable def add_polynomial : R[X] := W.polynomial.eval $ line_polynomial x₁ y₁ L
lemma C_add_polynomial :
C (W.add_polynomial x₁ y₁ L)
= (Y - C (line_polynomial x₁ y₁ L)) * (W.neg_polynomial - C (line_polynomial x₁ y₁ L))
+ W.polynomial :=
by { rw [add_polynomial, line_polynomial, weierstrass_curve.polynomial, neg_polynomial], eval_simp,
C_simp, ring1 }
lemma coordinate_ring.C_add_polynomial :
adjoin_root.mk W.polynomial (C (W.add_polynomial x₁ y₁ L))
= adjoin_root.mk W.polynomial
((Y - C (line_polynomial x₁ y₁ L)) * (W.neg_polynomial - C (line_polynomial x₁ y₁ L))) :=
adjoin_root.mk_eq_mk.mpr ⟨1, by rw [C_add_polynomial, add_sub_cancel', mul_one]⟩
lemma add_polynomial_eq : W.add_polynomial x₁ y₁ L = -cubic.to_poly
⟨1, -L ^ 2 - W.a₁ * L + W.a₂,
2 * x₁ * L ^ 2 + (W.a₁ * x₁ - 2 * y₁ - W.a₃) * L + (-W.a₁ * y₁ + W.a₄),
-x₁ ^ 2 * L ^ 2 + (2 * x₁ * y₁ + W.a₃ * x₁) * L - (y₁ ^ 2 + W.a₃ * y₁ - W.a₆)⟩ :=
by { rw [add_polynomial, line_polynomial, weierstrass_curve.polynomial, cubic.to_poly], eval_simp,
C_simp, ring1 }
/-- The $X$-coordinate of the addition of two affine points $(x_1, y_1)$ and $(x_2, y_2)$ in `W`,
where the line through them is not vertical and has a slope of $L$.
This depends on `W`, and has argument order: $x_1$, $x_2$, $L$. -/
@[simp] def add_X : R := L ^ 2 + W.a₁ * L - W.a₂ - x₁ - x₂
lemma base_change_add_X :
(W.base_change A).add_X (algebra_map R A x₁) (algebra_map R A x₂) (algebra_map R A L)
= algebra_map R A (W.add_X x₁ x₂ L) :=
by { simp only [add_X], map_simp, refl }
lemma base_change_add_X_of_base_change (x₁ x₂ L : A) :
(W.base_change B).add_X (algebra_map A B x₁) (algebra_map A B x₂) (algebra_map A B L)
= algebra_map A B ((W.base_change A).add_X x₁ x₂ L) :=
by rw [← base_change_add_X, base_change_base_change]
/-- The $Y$-coordinate, before applying the final negation, of the addition of two affine points
$(x_1, y_1)$ and $(x_2, y_2)$, where the line through them is not vertical and has a slope of $L$.
This depends on `W`, and has argument order: $x_1$, $x_2$, $y_1$, $L$. -/
@[simp] def add_Y' : R := L * (W.add_X x₁ x₂ L - x₁) + y₁
lemma base_change_add_Y' :
(W.base_change A).add_Y' (algebra_map R A x₁) (algebra_map R A x₂) (algebra_map R A y₁)
(algebra_map R A L) = algebra_map R A (W.add_Y' x₁ x₂ y₁ L) :=
by { simp only [add_Y', base_change_add_X], map_simp }
lemma base_change_add_Y'_of_base_change (x₁ x₂ y₁ L : A) :
(W.base_change B).add_Y' (algebra_map A B x₁) (algebra_map A B x₂) (algebra_map A B y₁)
(algebra_map A B L) = algebra_map A B ((W.base_change A).add_Y' x₁ x₂ y₁ L) :=
by rw [← base_change_add_Y', base_change_base_change]
/-- The $Y$-coordinate of the addition of two affine points $(x_1, y_1)$ and $(x_2, y_2)$ in `W`,
where the line through them is not vertical and has a slope of $L$.
This depends on `W`, and has argument order: $x_1$, $x_2$, $y_1$, $L$. -/
@[simp] def add_Y : R := W.neg_Y (W.add_X x₁ x₂ L) (W.add_Y' x₁ x₂ y₁ L)
lemma base_change_add_Y :
(W.base_change A).add_Y (algebra_map R A x₁) (algebra_map R A x₂) (algebra_map R A y₁)
(algebra_map R A L) = algebra_map R A (W.add_Y x₁ x₂ y₁ L) :=
by simp only [add_Y, base_change_add_Y', base_change_add_X, base_change_neg_Y]
lemma base_change_add_Y_of_base_change (x₁ x₂ y₁ L : A) :
(W.base_change B).add_Y (algebra_map A B x₁) (algebra_map A B x₂) (algebra_map A B y₁)
(algebra_map A B L) = algebra_map A B ((W.base_change A).add_Y x₁ x₂ y₁ L) :=
by rw [← base_change_add_Y, base_change_base_change]
lemma XY_ideal_add_eq :
XY_ideal W (W.add_X x₁ x₂ L) (C (W.add_Y x₁ x₂ y₁ L))
= span {adjoin_root.mk W.polynomial $ W.neg_polynomial - C (line_polynomial x₁ y₁ L)}
⊔ X_ideal W (W.add_X x₁ x₂ L) :=
begin
simp only [XY_ideal, X_ideal, X_class, Y_class, add_Y, add_Y', neg_Y, neg_polynomial,
line_polynomial],
conv_rhs { rw [sub_sub, ← neg_add', map_neg, span_singleton_neg, sup_comm, ← span_insert] },
rw [← span_pair_add_mul_right $ adjoin_root.mk _ $ C $ C $ W.a₁ + L, ← _root_.map_mul, ← map_add],
apply congr_arg (_ ∘ _ ∘ _ ∘ _),
C_simp,
ring1
end
lemma equation_add_iff :
W.equation (W.add_X x₁ x₂ L) (W.add_Y' x₁ x₂ y₁ L)
↔ (W.add_polynomial x₁ y₁ L).eval (W.add_X x₁ x₂ L) = 0 :=
by { rw [equation, add_Y', add_polynomial, line_polynomial, weierstrass_curve.polynomial],
eval_simp }
lemma nonsingular_add_of_eval_derivative_ne_zero
(hx' : W.equation (W.add_X x₁ x₂ L) (W.add_Y' x₁ x₂ y₁ L))
(hx : (derivative $ W.add_polynomial x₁ y₁ L).eval (W.add_X x₁ x₂ L) ≠ 0) :
W.nonsingular (W.add_X x₁ x₂ L) (W.add_Y' x₁ x₂ y₁ L) :=
begin
rw [nonsingular, and_iff_right hx', add_Y', polynomial_X, polynomial_Y],
eval_simp,
contrapose! hx,
rw [add_polynomial, line_polynomial, weierstrass_curve.polynomial],
eval_simp,
derivative_simp,
simp only [zero_add, add_zero, sub_zero, zero_mul, mul_one],
eval_simp,
linear_combination hx.left + L * hx.right with { normalization_tactic := `[norm_num1, ring1] }
end
/-! ### The type of nonsingular rational points on a Weierstrass curve -/
/-- A nonsingular rational point on a Weierstrass curve `W` over `R`. This is either the point at
infinity `weierstrass_curve.point.zero` or an affine point `weierstrass_curve.point.some` $(x, y)$
satisfying the equation $y^2 + a_1xy + a_3y = x^3 + a_2x^2 + a_4x + a_6$ of `W`. For an algebraic
extension `S` of `R`, the type of nonsingular `S`-rational points on `W` is denoted `W⟮S⟯`. -/
inductive point
| zero
| some {x y : R} (h : W.nonsingular x y)
localized "notation W⟮S⟯ := (W.base_change S).point" in weierstrass_curve
namespace point
instance : inhabited W.point := ⟨zero⟩
instance : has_zero W.point := ⟨zero⟩
@[simp] lemma zero_def : (zero : W.point) = 0 := rfl
end point
variables {W x₁ y₁}
lemma equation_neg_iff : W.equation x₁ (W.neg_Y x₁ y₁) ↔ W.equation x₁ y₁ :=
by { rw [equation_iff, equation_iff, neg_Y], congr' 2, ring1 }
lemma equation_neg_of (h : W.equation x₁ $ W.neg_Y x₁ y₁) : W.equation x₁ y₁ :=
equation_neg_iff.mp h
/-- The negation of an affine point in `W` lies in `W`. -/
lemma equation_neg (h : W.equation x₁ y₁) : W.equation x₁ $ W.neg_Y x₁ y₁ := equation_neg_iff.mpr h
lemma nonsingular_neg_iff : W.nonsingular x₁ (W.neg_Y x₁ y₁) ↔ W.nonsingular x₁ y₁ :=
begin
rw [nonsingular_iff, equation_neg_iff, ← neg_Y, neg_Y_neg_Y, ← @ne_comm _ y₁, nonsingular_iff],
exact and_congr_right' ((iff_congr not_and_distrib.symm not_and_distrib.symm).mpr $
not_iff_not_of_iff $ and_congr_left $ λ h, by rw [← h])
end
lemma nonsingular_neg_of (h : W.nonsingular x₁ $ W.neg_Y x₁ y₁) : W.nonsingular x₁ y₁ :=
nonsingular_neg_iff.mp h
/-- The negation of a nonsingular affine point in `W` is nonsingular. -/
lemma nonsingular_neg (h : W.nonsingular x₁ y₁) : W.nonsingular x₁ $ W.neg_Y x₁ y₁ :=
nonsingular_neg_iff.mpr h
namespace point
/-- The negation of a nonsingular rational point.
Given a nonsingular rational point `P`, use `-P` instead of `neg P`. -/
def neg : W.point → W.point
| 0 := 0
| (some h) := some $ nonsingular_neg h
instance : has_neg W.point := ⟨neg⟩
@[simp] lemma neg_def (P : W.point) : P.neg = -P := rfl
@[simp] lemma neg_zero : (-0 : W.point) = 0 := rfl
@[simp] lemma neg_some (h : W.nonsingular x₁ y₁) : -some h = some (nonsingular_neg h) := rfl
instance : has_involutive_neg W.point := ⟨neg, by { rintro (_ | _), { refl }, { simp, ring1 } }⟩
end point
end basic
section addition
/-! ### Slopes of lines through nonsingular rational points on a Weierstrass curve -/
open_locale classical
variables {F : Type u} [field F] (W : weierstrass_curve F) (K : Type v) [field K] [algebra F K]
(x₁ x₂ y₁ y₂ : F)
/-- The slope of the line through two affine points $(x_1, y_1)$ and $(x_2, y_2)$ in `W`.
If $x_1 \ne x_2$, then this line is the secant of `W` through $(x_1, y_1)$ and $(x_2, y_2)$,
and has slope $(y_1 - y_2) / (x_1 - x_2)$. Otherwise, if $y_1 \ne -y_1 - a_1x_1 - a_3$,
then this line is the tangent of `W` at $(x_1, y_1) = (x_2, y_2)$, and has slope
$(3x_1^2 + 2a_2x_1 + a_4 - a_1y_1) / (2y_1 + a_1x_1 + a_3)$. Otherwise, this line is vertical,
and has undefined slope, in which case this function returns the value 0.
This depends on `W`, and has argument order: $x_1$, $x_2$, $y_1$, $y_2$. -/
noncomputable def slope : F :=
if hx : x₁ = x₂ then if hy : y₁ = W.neg_Y x₂ y₂ then 0
else (3 * x₁ ^ 2 + 2 * W.a₂ * x₁ + W.a₄ - W.a₁ * y₁) / (y₁ - W.neg_Y x₁ y₁)
else (y₁ - y₂) / (x₁ - x₂)
variables {W x₁ x₂ y₁ y₂} (h₁ : W.nonsingular x₁ y₁) (h₂ : W.nonsingular x₂ y₂)
(h₁' : W.equation x₁ y₁) (h₂' : W.equation x₂ y₂)
@[simp] lemma slope_of_Y_eq (hx : x₁ = x₂) (hy : y₁ = W.neg_Y x₂ y₂) :
W.slope x₁ x₂ y₁ y₂ = 0 :=
by rw [slope, dif_pos hx, dif_pos hy]
@[simp] lemma slope_of_Y_ne (hx : x₁ = x₂) (hy : y₁ ≠ W.neg_Y x₂ y₂) :
W.slope x₁ x₂ y₁ y₂ = (3 * x₁ ^ 2 + 2 * W.a₂ * x₁ + W.a₄ - W.a₁ * y₁) / (y₁ - W.neg_Y x₁ y₁) :=
by rw [slope, dif_pos hx, dif_neg hy]
@[simp] lemma slope_of_X_ne (hx : x₁ ≠ x₂) : W.slope x₁ x₂ y₁ y₂ = (y₁ - y₂) / (x₁ - x₂) :=
by rw [slope, dif_neg hx]
lemma slope_of_Y_ne_eq_eval (hx : x₁ = x₂) (hy : y₁ ≠ W.neg_Y x₂ y₂) :
W.slope x₁ x₂ y₁ y₂
= -(W.polynomial_X.eval $ C y₁).eval x₁ / (W.polynomial_Y.eval $ C y₁).eval x₁ :=
by { rw [slope_of_Y_ne hx hy, eval_polynomial_X, neg_sub], congr' 1, rw [neg_Y, eval_polynomial_Y],
ring1 }
lemma base_change_slope :
(W.base_change K).slope (algebra_map F K x₁) (algebra_map F K x₂) (algebra_map F K y₁)
(algebra_map F K y₂) = algebra_map F K (W.slope x₁ x₂ y₁ y₂) :=
begin
by_cases hx : x₁ = x₂,
{ by_cases hy : y₁ = W.neg_Y x₂ y₂,
{ rw [slope_of_Y_eq hx hy, slope_of_Y_eq $ congr_arg _ hx, map_zero],
{ rw [hy, base_change_neg_Y] } },
{ rw [slope_of_Y_ne hx hy, slope_of_Y_ne $ congr_arg _ hx],
{ map_simp,
simpa only [base_change_neg_Y] },
{ rw [base_change_neg_Y],
contrapose! hy,
exact no_zero_smul_divisors.algebra_map_injective F K hy } } },
{ rw [slope_of_X_ne hx, slope_of_X_ne],
{ map_simp },
{ contrapose! hx,
exact no_zero_smul_divisors.algebra_map_injective F K hx } }
end
lemma base_change_slope_of_base_change {R : Type u} [comm_ring R] (W : weierstrass_curve R)
(F : Type v) [field F] [algebra R F] (K : Type w) [field K] [algebra R K] [algebra F K]
[is_scalar_tower R F K] (x₁ x₂ y₁ y₂ : F) :
(W.base_change K).slope (algebra_map F K x₁) (algebra_map F K x₂) (algebra_map F K y₁)
(algebra_map F K y₂) = algebra_map F K ((W.base_change F).slope x₁ x₂ y₁ y₂) :=
by rw [← base_change_slope, base_change_base_change]
include h₁' h₂'
lemma Y_eq_of_X_eq (hx : x₁ = x₂) : y₁ = y₂ ∨ y₁ = W.neg_Y x₂ y₂ :=
begin
rw [equation_iff] at h₁' h₂',
rw [← sub_eq_zero, ← @sub_eq_zero _ _ y₁, ← mul_eq_zero, neg_Y],
linear_combination h₁' - h₂' with { normalization_tactic := `[rw [hx], ring1] }
end
lemma Y_eq_of_Y_ne (hx : x₁ = x₂) (hy : y₁ ≠ W.neg_Y x₂ y₂) : y₁ = y₂ :=
or.resolve_right (Y_eq_of_X_eq h₁' h₂' hx) hy
lemma XY_ideal_eq₂ (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
XY_ideal W x₂ (C y₂) = XY_ideal W x₂ (line_polynomial x₁ y₁ $ W.slope x₁ x₂ y₁ y₂) :=
begin
have hy₂ : y₂ = (line_polynomial x₁ y₁ $ W.slope x₁ x₂ y₁ y₂).eval x₂ :=
begin
by_cases hx : x₁ = x₂,
{ rcases ⟨hx, Y_eq_of_Y_ne h₁' h₂' hx $ hxy hx⟩ with ⟨rfl, rfl⟩,
field_simp [line_polynomial, sub_ne_zero_of_ne (hxy rfl)] },
{ field_simp [line_polynomial, slope_of_X_ne hx, sub_ne_zero_of_ne hx],
ring1 }
end,
nth_rewrite_lhs 0 [hy₂],
simp only [XY_ideal, X_class, Y_class, line_polynomial],
rw [← span_pair_add_mul_right $ adjoin_root.mk W.polynomial $ C $ C $ -W.slope x₁ x₂ y₁ y₂,
← _root_.map_mul, ← map_add],
apply congr_arg (_ ∘ _ ∘ _ ∘ _),
eval_simp,
C_simp,
ring1
end
lemma add_polynomial_slope (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
W.add_polynomial x₁ y₁ (W.slope x₁ x₂ y₁ y₂)
= -((X - C x₁) * (X - C x₂) * (X - C (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂))) :=
begin
rw [add_polynomial_eq, neg_inj, cubic.prod_X_sub_C_eq, cubic.to_poly_injective],
by_cases hx : x₁ = x₂,
{ rcases ⟨hx, Y_eq_of_Y_ne h₁' h₂' hx (hxy hx)⟩ with ⟨rfl, rfl⟩,
rw [equation_iff] at h₁' h₂',
rw [slope_of_Y_ne rfl $ hxy rfl],
rw [neg_Y, ← sub_ne_zero] at hxy,
ext,
{ refl },
{ simp only [add_X],
ring1 },
{ field_simp [hxy rfl],
ring1 },
{ linear_combination -h₁' with { normalization_tactic := `[field_simp [hxy rfl], ring1] } } },
{ rw [equation_iff] at h₁' h₂',
rw [slope_of_X_ne hx],
rw [← sub_eq_zero] at hx,
ext,
{ refl },
{ simp only [add_X],
ring1 },
{ apply mul_right_injective₀ hx,
linear_combination h₂' - h₁' with { normalization_tactic := `[field_simp [hx], ring1] } },
{ apply mul_right_injective₀ hx,
linear_combination x₂ * h₁' - x₁ * h₂'
with { normalization_tactic := `[field_simp [hx], ring1] } } }
end
lemma coordinate_ring.C_add_polynomial_slope (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
adjoin_root.mk W.polynomial (C $ W.add_polynomial x₁ y₁ $ W.slope x₁ x₂ y₁ y₂)
= -(X_class W x₁ * X_class W x₂ * X_class W (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂)) :=
by simpa only [add_polynomial_slope h₁' h₂' hxy, map_neg, neg_inj, _root_.map_mul]
lemma derivative_add_polynomial_slope (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
derivative (W.add_polynomial x₁ y₁ $ W.slope x₁ x₂ y₁ y₂)
= -((X - C x₁) * (X - C x₂) + (X - C x₁) * (X - C (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂))
+ (X - C x₂) * (X - C (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂))) :=
by { rw [add_polynomial_slope h₁' h₂' hxy], derivative_simp, ring1 }
/-! ### The addition law on nonsingular rational points on a Weierstrass curve -/
/-- The addition of two affine points in `W` on a sloped line,
before applying the final negation that maps $Y$ to $-Y - a_1X - a_3$, lies in `W`. -/
lemma equation_add' (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
W.equation (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂) (W.add_Y' x₁ x₂ y₁ $ W.slope x₁ x₂ y₁ y₂) :=
by { rw [equation_add_iff, add_polynomial_slope h₁' h₂' hxy], eval_simp,
rw [neg_eq_zero, sub_self, mul_zero] }
/-- The addition of two affine points in `W` on a sloped line lies in `W`. -/
lemma equation_add (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
W.equation (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂) (W.add_Y x₁ x₂ y₁ $ W.slope x₁ x₂ y₁ y₂) :=
equation_neg $ equation_add' h₁' h₂' hxy
omit h₁' h₂'
include h₁ h₂
/-- The addition of two nonsingular affine points in `W` on a sloped line,
before applying the final negation that maps $Y$ to $-Y - a_1X - a_3$, is nonsingular. -/
lemma nonsingular_add' (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
W.nonsingular (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂) (W.add_Y' x₁ x₂ y₁ $ W.slope x₁ x₂ y₁ y₂) :=
begin
by_cases hx₁ : W.add_X x₁ x₂ (W.slope x₁ x₂ y₁ y₂) = x₁,
{ rwa [add_Y', hx₁, sub_self, mul_zero, zero_add] },
{ by_cases hx₂ : W.add_X x₁ x₂ (W.slope x₁ x₂ y₁ y₂) = x₂,
{ by_cases hx : x₁ = x₂,
{ subst hx,
contradiction },
{ rwa [add_Y', ← neg_sub, mul_neg, hx₂, slope_of_X_ne hx,
div_mul_cancel _ $ sub_ne_zero_of_ne hx, neg_sub, sub_add_cancel] } },
{ apply W.nonsingular_add_of_eval_derivative_ne_zero _ _ _ _ (equation_add' h₁.1 h₂.1 hxy),
rw [derivative_add_polynomial_slope h₁.left h₂.left hxy],
eval_simp,
simpa only [neg_ne_zero, sub_self, mul_zero, add_zero]
using mul_ne_zero (sub_ne_zero_of_ne hx₁) (sub_ne_zero_of_ne hx₂) } }
end
/-- The addition of two nonsingular affine points in `W` on a sloped line is nonsingular. -/
lemma nonsingular_add (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
W.nonsingular (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂) (W.add_Y x₁ x₂ y₁ $ W.slope x₁ x₂ y₁ y₂) :=
nonsingular_neg $ nonsingular_add' h₁ h₂ hxy
omit h₁ h₂
namespace point
variables {h₁ h₂}
/-- The addition of two nonsingular rational points.
Given two nonsingular rational points `P` and `Q`, use `P + Q` instead of `add P Q`. -/
noncomputable def add : W.point → W.point → W.point
| 0 P := P
| P 0 := P
| (@some _ _ _ x₁ y₁ h₁) (@some _ _ _ x₂ y₂ h₂) :=
if hx : x₁ = x₂ then if hy : y₁ = W.neg_Y x₂ y₂ then 0
else some $ nonsingular_add h₁ h₂ $ λ _, hy
else some $ nonsingular_add h₁ h₂ $ λ h, (hx h).elim
noncomputable instance : has_add W.point := ⟨add⟩
@[simp] lemma add_def (P Q : W.point) : P.add Q = P + Q := rfl
noncomputable instance : add_zero_class W.point :=
⟨0, (+), by rintro (_ | _); refl, by rintro (_ | _); refl⟩
@[simp] lemma some_add_some_of_Y_eq (hx : x₁ = x₂) (hy : y₁ = W.neg_Y x₂ y₂) :
some h₁ + some h₂ = 0 :=
by rw [← add_def, add, dif_pos hx, dif_pos hy]
@[simp] lemma some_add_self_of_Y_eq (hy : y₁ = W.neg_Y x₁ y₁) : some h₁ + some h₁ = 0 :=
some_add_some_of_Y_eq rfl hy
@[simp] lemma some_add_some_of_Y_ne (hx : x₁ = x₂) (hy : y₁ ≠ W.neg_Y x₂ y₂) :
some h₁ + some h₂ = some (nonsingular_add h₁ h₂ $ λ _, hy) :=
by rw [← add_def, add, dif_pos hx, dif_neg hy]
lemma some_add_some_of_Y_ne' (hx : x₁ = x₂) (hy : y₁ ≠ W.neg_Y x₂ y₂) :
some h₁ + some h₂ = -some (nonsingular_add' h₁ h₂ $ λ _, hy) :=
some_add_some_of_Y_ne hx hy
@[simp] lemma some_add_self_of_Y_ne (hy : y₁ ≠ W.neg_Y x₁ y₁) :
some h₁ + some h₁ = some (nonsingular_add h₁ h₁ $ λ _, hy) :=
some_add_some_of_Y_ne rfl hy
lemma some_add_self_of_Y_ne' (hy : y₁ ≠ W.neg_Y x₁ y₁) :
some h₁ + some h₁ = -some (nonsingular_add' h₁ h₁ $ λ _, hy) :=
some_add_some_of_Y_ne rfl hy
@[simp] lemma some_add_some_of_X_ne (hx : x₁ ≠ x₂) :
some h₁ + some h₂ = some (nonsingular_add h₁ h₂ $ λ h, (hx h).elim) :=
by rw [← add_def, add, dif_neg hx]
lemma some_add_some_of_X_ne' (hx : x₁ ≠ x₂) :
some h₁ + some h₂ = -some (nonsingular_add' h₁ h₂ $ λ h, (hx h).elim) :=
some_add_some_of_X_ne hx
end point
end addition
section group
/-! ### The axioms for nonsingular rational points on a Weierstrass curve -/
variables {F : Type u} [field F] {W : weierstrass_curve F} {x₁ x₂ y₁ y₂ : F}
(h₁ : W.nonsingular x₁ y₁) (h₂ : W.nonsingular x₂ y₂)
(h₁' : W.equation x₁ y₁) (h₂' : W.equation x₂ y₂)
include h₁
lemma XY_ideal_neg_mul : XY_ideal W x₁ (C $ W.neg_Y x₁ y₁) * XY_ideal W x₁ (C y₁) = X_ideal W x₁ :=
begin
have Y_rw :
(Y - C (C y₁)) * (Y - C (C (W.neg_Y x₁ y₁))) - C (X - C x₁)
* (C (X ^ 2 + C (x₁ + W.a₂) * X + C (x₁ ^ 2 + W.a₂ * x₁ + W.a₄)) - C (C W.a₁) * Y)
= W.polynomial * 1 :=
by linear_combination congr_arg C (congr_arg C ((W.equation_iff _ _).mp h₁.left).symm)
with { normalization_tactic := `[rw [neg_Y, weierstrass_curve.polynomial], C_simp, ring1] },
simp_rw [XY_ideal, X_class, Y_class, span_pair_mul_span_pair, mul_comm, ← _root_.map_mul,
adjoin_root.mk_eq_mk.mpr ⟨1, Y_rw⟩, _root_.map_mul, span_insert,
← span_singleton_mul_span_singleton, ← mul_sup, ← span_insert],
convert mul_top _ using 2,
simp_rw [← @set.image_singleton _ _ $ adjoin_root.mk _, ← set.image_insert_eq, ← map_span],
convert map_top (adjoin_root.mk W.polynomial) using 1,
apply congr_arg,
simp_rw [eq_top_iff_one, mem_span_insert', mem_span_singleton'],
cases ((W.nonsingular_iff' _ _).mp h₁).right with hx hy,
{ let W_X := W.a₁ * y₁ - (3 * x₁ ^ 2 + 2 * W.a₂ * x₁ + W.a₄),
refine ⟨C (C W_X⁻¹ * -(X + C (2 * x₁ + W.a₂))), C (C $ W_X⁻¹ * W.a₁), 0, C (C $ W_X⁻¹ * -1), _⟩,
rw [← mul_right_inj' $ C_ne_zero.mpr $ C_ne_zero.mpr hx],
simp only [mul_add, ← mul_assoc, ← C_mul, mul_inv_cancel hx],
C_simp,
ring1 },
{ let W_Y := 2 * y₁ + W.a₁ * x₁ + W.a₃,
refine ⟨0, C (C W_Y⁻¹), C (C $ W_Y⁻¹ * -1), 0, _⟩,
rw [neg_Y, ← mul_right_inj' $ C_ne_zero.mpr $ C_ne_zero.mpr hy],
simp only [mul_add, ← mul_assoc, ← C_mul, mul_inv_cancel hy],
C_simp,
ring1 }
end
private lemma XY_ideal'_mul_inv :
(XY_ideal W x₁ (C y₁) : fractional_ideal W.coordinate_ring⁰ W.function_field)
* (XY_ideal W x₁ (C $ W.neg_Y x₁ y₁) * (X_ideal W x₁)⁻¹) = 1 :=
by rw [← mul_assoc, ← fractional_ideal.coe_ideal_mul, mul_comm $ XY_ideal W _ _,
XY_ideal_neg_mul h₁, X_ideal,
fractional_ideal.coe_ideal_span_singleton_mul_inv W.function_field $ X_class_ne_zero W x₁]
omit h₁
include h₁' h₂'
lemma XY_ideal_mul_XY_ideal (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
X_ideal W (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂) * (XY_ideal W x₁ (C y₁) * XY_ideal W x₂ (C y₂))
= Y_ideal W (line_polynomial x₁ y₁ $ W.slope x₁ x₂ y₁ y₂)
* XY_ideal W (W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂)
(C $ W.add_Y x₁ x₂ y₁ $ W.slope x₁ x₂ y₁ y₂) :=
begin
have sup_rw : ∀ a b c d : ideal W.coordinate_ring, a ⊔ (b ⊔ (c ⊔ d)) = a ⊔ d ⊔ b ⊔ c :=
λ _ _ c _, by rw [← sup_assoc, @sup_comm _ _ c, sup_sup_sup_comm, ← sup_assoc],
rw [XY_ideal_add_eq, X_ideal, mul_comm, W.XY_ideal_eq₁ x₁ y₁ $ W.slope x₁ x₂ y₁ y₂, XY_ideal,
XY_ideal_eq₂ h₁' h₂' hxy, XY_ideal, span_pair_mul_span_pair],
simp_rw [span_insert, sup_rw, sup_mul, span_singleton_mul_span_singleton],
rw [← neg_eq_iff_eq_neg.mpr $ coordinate_ring.C_add_polynomial_slope h₁' h₂' hxy,
span_singleton_neg, coordinate_ring.C_add_polynomial, _root_.map_mul, Y_class],
simp_rw [mul_comm $ X_class W x₁, mul_assoc, ← span_singleton_mul_span_singleton, ← mul_sup],
rw [span_singleton_mul_span_singleton, ← span_insert,
← span_pair_add_mul_right $ -(X_class W $ W.add_X x₁ x₂ $ W.slope x₁ x₂ y₁ y₂), mul_neg,
← sub_eq_add_neg, ← sub_mul, ← map_sub, sub_sub_sub_cancel_right, span_insert,
← span_singleton_mul_span_singleton, ← sup_rw, ← sup_mul, ← sup_mul],
apply congr_arg (_ ∘ _),
convert top_mul _,
simp_rw [X_class, ← @set.image_singleton _ _ $ adjoin_root.mk _, ← map_span, ← ideal.map_sup,
eq_top_iff_one, mem_map_iff_of_surjective _ $ adjoin_root.mk_surjective
W.monic_polynomial, ← span_insert, mem_span_insert', mem_span_singleton'],
by_cases hx : x₁ = x₂,
{ rcases ⟨hx, Y_eq_of_Y_ne h₁' h₂' hx (hxy hx)⟩ with ⟨rfl, rfl⟩,
let y := (y₁ - W.neg_Y x₁ y₁) ^ 2,
replace hxy := pow_ne_zero 2 (sub_ne_zero_of_ne $ hxy rfl),
refine
⟨1 + C (C $ y⁻¹ * 4) * W.polynomial,
⟨C $ C y⁻¹ * (C 4 * X ^ 2 + C (4 * x₁ + W.b₂) * X + C (4 * x₁ ^ 2 + W.b₂ * x₁ + 2 * W.b₄)),
0, C (C y⁻¹) * (Y - W.neg_polynomial), _⟩,
by rw [map_add, map_one, _root_.map_mul, adjoin_root.mk_self, mul_zero, add_zero]⟩,
rw [weierstrass_curve.polynomial, neg_polynomial,
← mul_right_inj' $ C_ne_zero.mpr $ C_ne_zero.mpr hxy],
simp only [mul_add, ← mul_assoc, ← C_mul, mul_inv_cancel hxy],
linear_combination -4 * congr_arg C (congr_arg C $ (W.equation_iff _ _).mp h₁')
with { normalization_tactic := `[rw [b₂, b₄, neg_Y], C_simp, ring1] } },
{ replace hx := sub_ne_zero_of_ne hx,
refine ⟨_, ⟨⟨C $ C (x₁ - x₂)⁻¹, C $ C $ (x₁ - x₂)⁻¹ * -1, 0, _⟩, map_one _⟩⟩,
rw [← mul_right_inj' $ C_ne_zero.mpr $ C_ne_zero.mpr hx],
simp only [← mul_assoc, mul_add, ← C_mul, mul_inv_cancel hx],
C_simp,
ring1 }
end
omit h₁' h₂'
/-- The non-zero fractional ideal $\langle X - x, Y - y \rangle$ of $F(W)$ for some $x, y \in F$. -/
@[simp] noncomputable def XY_ideal' : (fractional_ideal W.coordinate_ring⁰ W.function_field)ˣ :=
units.mk_of_mul_eq_one _ _ $ XY_ideal'_mul_inv h₁
lemma XY_ideal'_eq :
(XY_ideal' h₁ : fractional_ideal W.coordinate_ring⁰ W.function_field) = XY_ideal W x₁ (C y₁) :=
rfl
local attribute [irreducible] coordinate_ring.comm_ring
lemma mk_XY_ideal'_mul_mk_XY_ideal'_of_Y_eq :
class_group.mk (XY_ideal' $ nonsingular_neg h₁) * class_group.mk (XY_ideal' h₁) = 1 :=
begin
rw [← _root_.map_mul],
exact (class_group.mk_eq_one_of_coe_ideal $
by exact (fractional_ideal.coe_ideal_mul _ _).symm.trans
(fractional_ideal.coe_ideal_inj.mpr $ XY_ideal_neg_mul h₁)).mpr
⟨_, X_class_ne_zero W _, rfl⟩
end
lemma mk_XY_ideal'_mul_mk_XY_ideal' (hxy : x₁ = x₂ → y₁ ≠ W.neg_Y x₂ y₂) :
class_group.mk (XY_ideal' h₁) * class_group.mk (XY_ideal' h₂)
= class_group.mk (XY_ideal' $ nonsingular_add h₁ h₂ hxy) :=
begin
rw [← _root_.map_mul],
exact (class_group.mk_eq_mk_of_coe_ideal (by exact (fractional_ideal.coe_ideal_mul _ _).symm) $
XY_ideal'_eq _).mpr ⟨_, _, X_class_ne_zero W _, Y_class_ne_zero W _,
XY_ideal_mul_XY_ideal h₁.left h₂.left hxy⟩
end
namespace point
/-- The set function mapping an affine point $(x, y)$ of `W` to the class of the non-zero fractional
ideal $\langle X - x, Y - y \rangle$ of $F(W)$ in the class group of $F[W]$. -/
@[simp] noncomputable def to_class_fun : W.point → additive (class_group W.coordinate_ring)
| 0 := 0
| (some h) := additive.of_mul $ class_group.mk $ XY_ideal' h
/-- The group homomorphism mapping an affine point $(x, y)$ of `W` to the class of the non-zero
fractional ideal $\langle X - x, Y - y \rangle$ of $F(W)$ in the class group of $F[W]$. -/
@[simps] noncomputable def to_class : W.point →+ additive (class_group W.coordinate_ring) :=
{ to_fun := to_class_fun,
map_zero' := rfl,
map_add' :=
begin
rintro (_ | @⟨x₁, y₁, h₁⟩) (_ | @⟨x₂, y₂, h₂⟩),
any_goals { simp only [zero_def, to_class_fun, _root_.zero_add, _root_.add_zero] },
by_cases hx : x₁ = x₂,
{ by_cases hy : y₁ = W.neg_Y x₂ y₂,
{ substs hx hy,
simpa only [some_add_some_of_Y_eq rfl rfl]
using (mk_XY_ideal'_mul_mk_XY_ideal'_of_Y_eq h₂).symm },
{ simpa only [some_add_some_of_Y_ne hx hy]
using (mk_XY_ideal'_mul_mk_XY_ideal' h₁ h₂ $ λ _, hy).symm } },
{ simpa only [some_add_some_of_X_ne hx]
using (mk_XY_ideal'_mul_mk_XY_ideal' h₁ h₂ $ λ h, (hx h).elim).symm }
end }
@[simp] lemma to_class_zero : to_class (0 : W.point) = 0 := rfl
lemma to_class_some : to_class (some h₁) = class_group.mk (XY_ideal' h₁) := rfl
@[simp] lemma add_eq_zero (P Q : W.point) : P + Q = 0 ↔ P = -Q :=
begin
rcases ⟨P, Q⟩ with ⟨_ | @⟨x₁, y₁, _⟩, _ | @⟨x₂, y₂, _⟩⟩,
any_goals { refl },
{ rw [zero_def, zero_add, ← neg_eq_iff_eq_neg, neg_zero, eq_comm] },
{ simp only [neg_some],
split,
{ intro h,
by_cases hx : x₁ = x₂,
{ by_cases hy : y₁ = W.neg_Y x₂ y₂,
{ exact ⟨hx, hy⟩ },
{ rw [some_add_some_of_Y_ne hx hy] at h,
contradiction } },
{ rw [some_add_some_of_X_ne hx] at h,
contradiction } },
{ exact λ ⟨hx, hy⟩, some_add_some_of_Y_eq hx hy } }
end
@[simp] lemma add_left_neg (P : W.point) : -P + P = 0 := by rw [add_eq_zero]
@[simp] lemma neg_add_eq_zero (P Q : W.point) : -P + Q = 0 ↔ P = Q := by rw [add_eq_zero, neg_inj]
lemma to_class_eq_zero (P : W.point) : to_class P = 0 ↔ P = 0 :=
⟨begin
intro hP,
rcases P with (_ | @⟨_, _, ⟨h, _⟩⟩),
{ refl },
{ rcases (class_group.mk_eq_one_of_coe_ideal $ by refl).mp hP with ⟨p, h0, hp⟩,
apply (p.nat_degree_norm_ne_one _).elim,
rw [← finrank_quotient_span_eq_nat_degree_norm W^.coordinate_ring.basis h0,
← (quotient_equiv_alg_of_eq F hp).to_linear_equiv.finrank_eq,
(quotient_XY_ideal_equiv W h).to_linear_equiv.finrank_eq, finite_dimensional.finrank_self] }
end, congr_arg to_class⟩
lemma to_class_injective : function.injective $ @to_class _ _ W :=
begin
rintro (_ | h) _ hP,
all_goals { rw [← neg_add_eq_zero, ← to_class_eq_zero, map_add, ← hP] },
{ exact zero_add 0 },
{ exact mk_XY_ideal'_mul_mk_XY_ideal'_of_Y_eq h }
end
lemma add_comm (P Q : W.point) : P + Q = Q + P :=
to_class_injective $ by simp only [map_add, add_comm]
lemma add_assoc (P Q R : W.point) : P + Q + R = P + (Q + R) :=
to_class_injective $ by simp only [map_add, add_assoc]
noncomputable instance : add_comm_group W.point :=
{ zero := zero,
neg := neg,
add := add,
zero_add := zero_add,
add_zero := add_zero,
add_left_neg := add_left_neg,
add_comm := add_comm,
add_assoc := add_assoc }
end point
end group
section base_change
/-! ### Nonsingular rational points on a base changed Weierstrass curve -/
variables {R : Type u} [comm_ring R] (W : weierstrass_curve R) (F : Type v) [field F] [algebra R F]
(K : Type w) [field K] [algebra R K] [algebra F K] [is_scalar_tower R F K]
namespace point
open_locale weierstrass_curve
/-- The function from `W⟮F⟯` to `W⟮K⟯` induced by a base change from `F` to `K`. -/
def of_base_change_fun : W⟮F⟯ → W⟮K⟯
| 0 := 0
| (some h) := some $ (nonsingular_iff_base_change_of_base_change W F K _ _).mp h
/-- The group homomorphism from `W⟮F⟯` to `W⟮K⟯` induced by a base change from `F` to `K`. -/
@[simps] def of_base_change : W⟮F⟯ →+ W⟮K⟯ :=
{ to_fun := of_base_change_fun W F K,
map_zero' := rfl,
map_add' :=
begin
rintro (_ | @⟨x₁, y₁, _⟩) (_ | @⟨x₂, y₂, _⟩),
any_goals { refl },
by_cases hx : x₁ = x₂,
{ by_cases hy : y₁ = (W.base_change F).neg_Y x₂ y₂,
{ simp only [some_add_some_of_Y_eq hx hy, of_base_change_fun],
rw [some_add_some_of_Y_eq $ congr_arg _ hx],
{ rw [hy, base_change_neg_Y_of_base_change] } },
{ simp only [some_add_some_of_Y_ne hx hy, of_base_change_fun],
rw [some_add_some_of_Y_ne $ congr_arg _ hx],
{ simp only [base_change_add_X_of_base_change, base_change_add_Y_of_base_change,
base_change_slope_of_base_change],
exact ⟨rfl, rfl⟩ },
{ rw [base_change_neg_Y_of_base_change],
contrapose! hy,
exact no_zero_smul_divisors.algebra_map_injective F K hy } } },
{ simp only [some_add_some_of_X_ne hx, of_base_change_fun],
rw [some_add_some_of_X_ne],
{ simp only [base_change_add_X_of_base_change, base_change_add_Y_of_base_change,
base_change_slope_of_base_change],
exact ⟨rfl, rfl⟩ },
{ contrapose! hx,
exact no_zero_smul_divisors.algebra_map_injective F K hx } }
end }
lemma of_base_change_injective : function.injective $ of_base_change W F K :=
begin
rintro (_ | _) (_ | _) h,
{ refl },
any_goals { contradiction },
simp only,
exact ⟨no_zero_smul_divisors.algebra_map_injective F K (some.inj h).left,
no_zero_smul_divisors.algebra_map_injective F K (some.inj h).right⟩
end
end point
end base_change
end weierstrass_curve
namespace elliptic_curve
/-! ### Rational points on an elliptic curve -/
namespace point
variables {R : Type} [nontrivial R] [comm_ring R] (E : elliptic_curve R)
/-- An affine point on an elliptic curve `E` over `R`. -/
def mk {x y : R} (h : E.equation x y) : E.point := weierstrass_curve.point.some $ E.nonsingular h
end point
end elliptic_curve
|
b8c7540d861a08c8e14bd5c411163e6a1dbcb428 | a0e23cfdd129a671bf3154ee1a8a3a72bf4c7940 | /src/Lean/Elab/PreDefinition/WF.lean | f9e1021e5a7b60a1ab99386713d2fff4d5870c93 | [
"Apache-2.0"
] | permissive | WojciechKarpiel/lean4 | 7f89706b8e3c1f942b83a2c91a3a00b05da0e65b | f6e1314fa08293dea66a329e05b6c196a0189163 | refs/heads/master | 1,686,633,402,214 | 1,625,821,189,000 | 1,625,821,258,000 | 384,640,886 | 0 | 0 | Apache-2.0 | 1,625,903,617,000 | 1,625,903,026,000 | null | UTF-8 | Lean | false | false | 396 | lean | /-
Copyright (c) 2020 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
import Lean.Elab.PreDefinition.Basic
namespace Lean
namespace Elab
open Meta
def WFRecursion (preDefs : Array PreDefinition) : TermElabM Unit :=
throwError "well founded recursion has not been implemented yet"
end Elab
end Lean
|
d940e3e00ee80f1d9e107b98af86e262804316bc | a45212b1526d532e6e83c44ddca6a05795113ddc | /src/data/list/default.lean | 1b9d0bb48acd80b21fc844312c2cbccb9a7e298d | [
"Apache-2.0"
] | permissive | fpvandoorn/mathlib | b21ab4068db079cbb8590b58fda9cc4bc1f35df4 | b3433a51ea8bc07c4159c1073838fc0ee9b8f227 | refs/heads/master | 1,624,791,089,608 | 1,556,715,231,000 | 1,556,715,231,000 | 165,722,980 | 5 | 0 | Apache-2.0 | 1,552,657,455,000 | 1,547,494,646,000 | Lean | UTF-8 | Lean | false | false | 182 | lean | /-
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Jeremy Avigad
-/
import data.list.basic
|
774f4da3abf650d376bee4e4f81ffa5683204381 | 271e26e338b0c14544a889c31c30b39c989f2e0f | /src/Init/Lean/Elab/Import.lean | 35ea571892024099e028032c0807044e79dffc72 | [
"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 | 1,993 | lean | /-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura, Sebastian Ullrich
-/
prelude
import Init.Lean.Parser.Module
namespace Lean
namespace Elab
def headerToImports (header : Syntax) : List Import :=
let header := header.asNode;
let imports := if (header.getArg 0).isNone then [{Import . module := `Init.Default}] else [];
imports ++ (header.getArg 1).getArgs.toList.map (fun stx =>
-- `stx` is of the form `(Module.import "import" "runtime"? id)
let runtime := !(stx.getArg 1).isNone;
let id := stx.getIdAt 2;
{ module := normalizeModuleName id, runtimeOnly := runtime })
def processHeader (header : Syntax) (messages : MessageLog) (ctx : Parser.ParserContextCore) (trustLevel : UInt32 := 0) : IO (Environment × MessageLog) :=
catch
(do env ← importModules (headerToImports header) trustLevel;
pure (env, messages))
(fun e => do
env ← mkEmptyEnvironment;
let spos := header.getPos.getD 0;
let pos := ctx.fileMap.toPosition spos;
pure (env, messages.add { fileName := ctx.fileName, data := toString e, pos := pos }))
def parseImports (input : String) (fileName : Option String := none) : IO (List Import × Position × MessageLog) := do
env ← mkEmptyEnvironment;
let fileName := fileName.getD "<input>";
let ctx := Parser.mkParserContextCore env input fileName;
match Parser.parseHeader env ctx with
| (header, parserState, messages) => do
pure (headerToImports header, ctx.fileMap.toPosition parserState.pos, messages)
@[export lean_parse_imports]
def parseImportsExport (input : String) (fileName : Option String) : IO (List Import × Position × List Message) := do
(imports, pos, log) ← parseImports input fileName;
pure (imports, pos, log.toList)
@[export lean_print_deps]
def printDeps (deps : List Import) : IO Unit :=
deps.forM $ fun dep => do
fname ← findOLean dep.module;
IO.println fname
end Elab
end Lean
|
9a73ebdeaded0e95693fd40a777afe5019c2558f | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/category_theory/preadditive/projective_resolution.lean | 16f66b844bf9e05024b1b5f8e88eaa20d5ea0238 | [
"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 | 13,101 | lean | /-
Copyright (c) 2021 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import category_theory.preadditive.projective
import algebra.homology.single
import algebra.homology.homotopy_category
/-!
# Projective resolutions
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
A projective resolution `P : ProjectiveResolution Z` of an object `Z : C` consists of
a `ℕ`-indexed chain complex `P.complex` of projective objects,
along with a chain map `P.π` from `C` to the chain complex consisting just of `Z` in degree zero,
so that the augmented chain complex is exact.
When `C` is abelian, this exactness condition is equivalent to `π` being a quasi-isomorphism.
It turns out that this formulation allows us to set up the basic theory of derived functors
without even assuming `C` is abelian.
(Typically, however, to show `has_projective_resolutions C`
one will assume `enough_projectives C` and `abelian C`.
This construction appears in `category_theory.abelian.projectives`.)
We show that given `P : ProjectiveResolution X` and `Q : ProjectiveResolution Y`,
any morphism `X ⟶ Y` admits a lift to a chain map `P.complex ⟶ Q.complex`.
(It is a lift in the sense that
the projection maps `P.π` and `Q.π` intertwine the lift and the original morphism.)
Moreover, we show that any two such lifts are homotopic.
As a consequence, if every object admits a projective resolution,
we can construct a functor `projective_resolutions C : C ⥤ homotopy_category C`.
-/
noncomputable theory
open category_theory
open category_theory.limits
universes v u
namespace category_theory
variables {C : Type u} [category.{v} C]
open projective
section
variables [has_zero_object C] [has_zero_morphisms C] [has_equalizers C] [has_images C]
/--
A `ProjectiveResolution Z` consists of a bundled `ℕ`-indexed chain complex of projective objects,
along with a quasi-isomorphism to the complex consisting of just `Z` supported in degree `0`.
(We don't actually ask here that the chain map is a quasi-iso, just exactness everywhere:
that `π` is a quasi-iso is a lemma when the category is abelian.
Should we just ask for it here?)
Except in situations where you want to provide a particular projective resolution
(for example to compute a derived functor),
you will not typically need to use this bundled object, and will instead use
* `projective_resolution Z`: the `ℕ`-indexed chain complex
(equipped with `projective` and `exact` instances)
* `projective_resolution.π Z`: the chain map from `projective_resolution Z` to
`(single C _ 0).obj Z` (all the components are equipped with `epi` instances,
and when the category is `abelian` we will show `π` is a quasi-iso).
-/
@[nolint has_nonempty_instance]
structure ProjectiveResolution (Z : C) :=
(complex : chain_complex C ℕ)
(π : homological_complex.hom complex ((chain_complex.single₀ C).obj Z))
(projective : ∀ n, projective (complex.X n) . tactic.apply_instance)
(exact₀ : exact (complex.d 1 0) (π.f 0))
(exact : ∀ n, exact (complex.d (n+2) (n+1)) (complex.d (n+1) n))
(epi : epi (π.f 0) . tactic.apply_instance)
attribute [instance] ProjectiveResolution.projective ProjectiveResolution.epi
/--
An object admits a projective resolution.
-/
class has_projective_resolution (Z : C) : Prop :=
(out [] : nonempty (ProjectiveResolution Z))
section
variables (C)
/--
You will rarely use this typeclass directly: it is implied by the combination
`[enough_projectives C]` and `[abelian C]`.
By itself it's enough to set up the basic theory of derived functors.
-/
class has_projective_resolutions : Prop :=
(out : ∀ Z : C, has_projective_resolution Z)
attribute [instance, priority 100] has_projective_resolutions.out
end
namespace ProjectiveResolution
@[simp] lemma π_f_succ {Z : C} (P : ProjectiveResolution Z) (n : ℕ) :
P.π.f (n+1) = 0 :=
begin
apply zero_of_target_iso_zero,
dsimp, refl,
end
@[simp] lemma complex_d_comp_π_f_zero {Z : C} (P : ProjectiveResolution Z) :
P.complex.d 1 0 ≫ P.π.f 0 = 0 :=
P.exact₀.w
@[simp] lemma complex_d_succ_comp {Z : C} (P : ProjectiveResolution Z) (n : ℕ) :
P.complex.d (n + 2) (n + 1) ≫ P.complex.d (n + 1) n = 0 :=
(P.exact _).w
instance {Z : C} (P : ProjectiveResolution Z) (n : ℕ) : category_theory.epi (P.π.f n) :=
by cases n; apply_instance
/-- A projective object admits a trivial projective resolution: itself in degree 0. -/
def self (Z : C) [category_theory.projective Z] : ProjectiveResolution Z :=
{ complex := (chain_complex.single₀ C).obj Z,
π := 𝟙 ((chain_complex.single₀ C).obj Z),
projective := λ n, begin
cases n,
{ dsimp, apply_instance, },
{ dsimp, apply_instance, },
end,
exact₀ := by { dsimp, exact exact_zero_mono _ },
exact := λ n, by { dsimp, exact exact_of_zero _ _ },
epi := by { dsimp, apply_instance, }, }
/-- Auxiliary construction for `lift`. -/
def lift_f_zero {Y Z : C} (f : Y ⟶ Z) (P : ProjectiveResolution Y) (Q : ProjectiveResolution Z) :
P.complex.X 0 ⟶ Q.complex.X 0 :=
factor_thru (P.π.f 0 ≫ f) (Q.π.f 0)
/-- Auxiliary construction for `lift`. -/
def lift_f_one {Y Z : C} (f : Y ⟶ Z) (P : ProjectiveResolution Y) (Q : ProjectiveResolution Z) :
P.complex.X 1 ⟶ Q.complex.X 1 :=
exact.lift (P.complex.d 1 0 ≫ lift_f_zero f P Q) (Q.complex.d 1 0) (Q.π.f 0) Q.exact₀
(by simp [lift_f_zero, P.exact₀.w_assoc])
/-- Auxiliary lemma for `lift`. -/
@[simp] lemma lift_f_one_zero_comm
{Y Z : C} (f : Y ⟶ Z) (P : ProjectiveResolution Y) (Q : ProjectiveResolution Z) :
lift_f_one f P Q ≫ Q.complex.d 1 0 = P.complex.d 1 0 ≫ lift_f_zero f P Q :=
begin
dsimp [lift_f_zero, lift_f_one],
simp,
end
/-- Auxiliary construction for `lift`. -/
def lift_f_succ {Y Z : C} (P : ProjectiveResolution Y) (Q : ProjectiveResolution Z)
(n : ℕ) (g : P.complex.X n ⟶ Q.complex.X n) (g' : P.complex.X (n+1) ⟶ Q.complex.X (n+1))
(w : g' ≫ Q.complex.d (n+1) n = P.complex.d (n+1) n ≫ g) :
Σ' g'' : P.complex.X (n+2) ⟶ Q.complex.X (n+2),
g'' ≫ Q.complex.d (n+2) (n+1) = P.complex.d (n+2) (n+1) ≫ g' :=
⟨exact.lift
(P.complex.d (n+2) (n+1) ≫ g') ((Q.complex.d (n+2) (n+1))) (Q.complex.d (n+1) n) (Q.exact _)
(by simp [w]), (by simp)⟩
/-- A morphism in `C` lifts to a chain map between projective resolutions. -/
def lift {Y Z : C} (f : Y ⟶ Z) (P : ProjectiveResolution Y) (Q : ProjectiveResolution Z) :
P.complex ⟶ Q.complex :=
chain_complex.mk_hom _ _ (lift_f_zero f _ _) (lift_f_one f _ _) (lift_f_one_zero_comm f _ _)
(λ n ⟨g, g', w⟩, lift_f_succ P Q n g g' w)
/-- The resolution maps intertwine the lift of a morphism and that morphism. -/
@[simp, reassoc]
lemma lift_commutes
{Y Z : C} (f : Y ⟶ Z) (P : ProjectiveResolution Y) (Q : ProjectiveResolution Z) :
lift f P Q ≫ Q.π = P.π ≫ (chain_complex.single₀ C).map f :=
by { ext, dsimp [lift, lift_f_zero], apply factor_thru_comp, }
-- Now that we've checked this property of the lift,
-- we can seal away the actual definition.
attribute [irreducible] lift
end ProjectiveResolution
end
namespace ProjectiveResolution
variables [has_zero_object C] [preadditive C] [has_equalizers C] [has_images C]
/-- An auxiliary definition for `lift_homotopy_zero`. -/
def lift_homotopy_zero_zero {Y Z : C} {P : ProjectiveResolution Y} {Q : ProjectiveResolution Z}
(f : P.complex ⟶ Q.complex)
(comm : f ≫ Q.π = 0) : P.complex.X 0 ⟶ Q.complex.X 1 :=
exact.lift (f.f 0) (Q.complex.d 1 0) (Q.π.f 0) Q.exact₀
(congr_fun (congr_arg homological_complex.hom.f comm) 0)
/-- An auxiliary definition for `lift_homotopy_zero`. -/
def lift_homotopy_zero_one {Y Z : C} {P : ProjectiveResolution Y} {Q : ProjectiveResolution Z}
(f : P.complex ⟶ Q.complex)
(comm : f ≫ Q.π = 0) : P.complex.X 1 ⟶ Q.complex.X 2 :=
exact.lift
(f.f 1 - P.complex.d 1 0 ≫ lift_homotopy_zero_zero f comm) (Q.complex.d 2 1) (Q.complex.d 1 0)
(Q.exact _) (by simp [lift_homotopy_zero_zero])
/-- An auxiliary definition for `lift_homotopy_zero`. -/
def lift_homotopy_zero_succ {Y Z : C} {P : ProjectiveResolution Y} {Q : ProjectiveResolution Z}
(f : P.complex ⟶ Q.complex) (n : ℕ)
(g : P.complex.X n ⟶ Q.complex.X (n + 1)) (g' : P.complex.X (n + 1) ⟶ Q.complex.X (n + 2))
(w : f.f (n + 1) = P.complex.d (n + 1) n ≫ g + g' ≫ Q.complex.d (n + 2) (n + 1)) :
P.complex.X (n + 2) ⟶ Q.complex.X (n + 3) :=
exact.lift
(f.f (n+2) - P.complex.d (n+2) (n+1) ≫ g') (Q.complex.d (n+3) (n+2)) (Q.complex.d (n+2) (n+1))
(Q.exact _) (by simp [w])
/-- Any lift of the zero morphism is homotopic to zero. -/
def lift_homotopy_zero {Y Z : C} {P : ProjectiveResolution Y} {Q : ProjectiveResolution Z}
(f : P.complex ⟶ Q.complex)
(comm : f ≫ Q.π = 0) :
homotopy f 0 :=
homotopy.mk_inductive _ (lift_homotopy_zero_zero f comm) (by simp [lift_homotopy_zero_zero])
(lift_homotopy_zero_one f comm) (by simp [lift_homotopy_zero_one])
(λ n ⟨g, g', w⟩, ⟨lift_homotopy_zero_succ f n g g' w, by simp [lift_homotopy_zero_succ, w]⟩)
/-- Two lifts of the same morphism are homotopic. -/
def lift_homotopy {Y Z : C} (f : Y ⟶ Z) {P : ProjectiveResolution Y} {Q : ProjectiveResolution Z}
(g h : P.complex ⟶ Q.complex)
(g_comm : g ≫ Q.π = P.π ≫ (chain_complex.single₀ C).map f)
(h_comm : h ≫ Q.π = P.π ≫ (chain_complex.single₀ C).map f) :
homotopy g h :=
homotopy.equiv_sub_zero.inv_fun (lift_homotopy_zero _ (by simp [g_comm, h_comm]))
/-- The lift of the identity morphism is homotopic to the identity chain map. -/
def lift_id_homotopy (X : C) (P : ProjectiveResolution X) :
homotopy (lift (𝟙 X) P P) (𝟙 P.complex) :=
by { apply lift_homotopy (𝟙 X); simp, }
/-- The lift of a composition is homotopic to the composition of the lifts. -/
def lift_comp_homotopy {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z)
(P : ProjectiveResolution X) (Q : ProjectiveResolution Y) (R : ProjectiveResolution Z) :
homotopy (lift (f ≫ g) P R) (lift f P Q ≫ lift g Q R) :=
by { apply lift_homotopy (f ≫ g); simp, }
-- We don't care about the actual definitions of these homotopies.
attribute [irreducible] lift_homotopy_zero lift_homotopy lift_id_homotopy lift_comp_homotopy
/-- Any two projective resolutions are homotopy equivalent. -/
def homotopy_equiv {X : C} (P Q : ProjectiveResolution X) :
homotopy_equiv P.complex Q.complex :=
{ hom := lift (𝟙 X) P Q,
inv := lift (𝟙 X) Q P,
homotopy_hom_inv_id := begin
refine (lift_comp_homotopy (𝟙 X) (𝟙 X) P Q P).symm.trans _,
simp [category.id_comp],
apply lift_id_homotopy,
end,
homotopy_inv_hom_id := begin
refine (lift_comp_homotopy (𝟙 X) (𝟙 X) Q P Q).symm.trans _,
simp [category.id_comp],
apply lift_id_homotopy,
end, }
@[simp, reassoc] lemma homotopy_equiv_hom_π {X : C} (P Q : ProjectiveResolution X) :
(homotopy_equiv P Q).hom ≫ Q.π = P.π :=
by simp [homotopy_equiv]
@[simp, reassoc] lemma homotopy_equiv_inv_π {X : C} (P Q : ProjectiveResolution X) :
(homotopy_equiv P Q).inv ≫ P.π = Q.π :=
by simp [homotopy_equiv]
end ProjectiveResolution
section
variables [has_zero_morphisms C] [has_zero_object C] [has_equalizers C] [has_images C]
/-- An arbitrarily chosen projective resolution of an object. -/
abbreviation projective_resolution (Z : C) [has_projective_resolution Z] : chain_complex C ℕ :=
(has_projective_resolution.out Z).some.complex
/-- The chain map from the arbitrarily chosen projective resolution `projective_resolution Z`
back to the chain complex consisting of `Z` supported in degree `0`. -/
abbreviation projective_resolution.π (Z : C) [has_projective_resolution Z] :
projective_resolution Z ⟶ (chain_complex.single₀ C).obj Z :=
(has_projective_resolution.out Z).some.π
/-- The lift of a morphism to a chain map between the arbitrarily chosen projective resolutions. -/
abbreviation projective_resolution.lift {X Y : C} (f : X ⟶ Y)
[has_projective_resolution X] [has_projective_resolution Y] :
projective_resolution X ⟶ projective_resolution Y :=
ProjectiveResolution.lift f _ _
end
variables (C) [preadditive C] [has_zero_object C] [has_equalizers C] [has_images C]
[has_projective_resolutions C]
/--
Taking projective resolutions is functorial,
if considered with target the homotopy category
(`ℕ`-indexed chain complexes and chain maps up to homotopy).
-/
def projective_resolutions : C ⥤ homotopy_category C (complex_shape.down ℕ) :=
{ obj := λ X, (homotopy_category.quotient _ _).obj (projective_resolution X),
map := λ X Y f, (homotopy_category.quotient _ _).map (projective_resolution.lift f),
map_id' := λ X, begin
rw ←(homotopy_category.quotient _ _).map_id,
apply homotopy_category.eq_of_homotopy,
apply ProjectiveResolution.lift_id_homotopy,
end,
map_comp' := λ X Y Z f g, begin
rw ←(homotopy_category.quotient _ _).map_comp,
apply homotopy_category.eq_of_homotopy,
apply ProjectiveResolution.lift_comp_homotopy,
end, }
end category_theory
|
e90dfad954fc0b058b57a5915deb26f82c43ed0b | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/group_theory/group_action/sub_mul_action.lean | 5d03221e6e8cf93f833f69ec3c133574b7114e53 | [
"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 | 7,158 | lean | /-
Copyright (c) 2020 Eric Wieser. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Eric Wieser
-/
import algebra.hom.group_action
import algebra.module.basic
import data.set_like.basic
import group_theory.group_action.basic
/-!
# Sets invariant to a `mul_action`
In this file we define `sub_mul_action R M`; a subset of a `mul_action R M` which is closed with
respect to scalar multiplication.
For most uses, typically `submodule R M` is more powerful.
## Main definitions
* `sub_mul_action.mul_action` - the `mul_action R M` transferred to the subtype.
* `sub_mul_action.mul_action'` - the `mul_action S M` transferred to the subtype when
`is_scalar_tower S R M`.
* `sub_mul_action.is_scalar_tower` - the `is_scalar_tower S R M` transferred to the subtype.
## Tags
submodule, mul_action
-/
open function
universes u u' u'' v
variables {S : Type u'} {T : Type u''} {R : Type u} {M : Type v}
set_option old_structure_cmd true
/-- A sub_mul_action is a set which is closed under scalar multiplication. -/
structure sub_mul_action (R : Type u) (M : Type v) [has_smul R M] : Type v :=
(carrier : set M)
(smul_mem' : ∀ (c : R) {x : M}, x ∈ carrier → c • x ∈ carrier)
namespace sub_mul_action
variables [has_smul R M]
instance : set_like (sub_mul_action R M) M :=
⟨sub_mul_action.carrier, λ p q h, by cases p; cases q; congr'⟩
@[simp] lemma mem_carrier {p : sub_mul_action R M} {x : M} : x ∈ p.carrier ↔ x ∈ (p : set M) :=
iff.rfl
@[ext] theorem ext {p q : sub_mul_action R M} (h : ∀ x, x ∈ p ↔ x ∈ q) : p = q := set_like.ext h
/-- Copy of a sub_mul_action with a new `carrier` equal to the old one. Useful to fix definitional
equalities.-/
protected def copy (p : sub_mul_action R M) (s : set M) (hs : s = ↑p) : sub_mul_action R M :=
{ carrier := s,
smul_mem' := hs.symm ▸ p.smul_mem' }
@[simp] lemma coe_copy (p : sub_mul_action R M) (s : set M) (hs : s = ↑p) :
(p.copy s hs : set M) = s := rfl
lemma copy_eq (p : sub_mul_action R M) (s : set M) (hs : s = ↑p) : p.copy s hs = p :=
set_like.coe_injective hs
instance : has_bot (sub_mul_action R M) :=
⟨{ carrier := ∅, smul_mem' := λ c, set.not_mem_empty}⟩
instance : inhabited (sub_mul_action R M) := ⟨⊥⟩
end sub_mul_action
namespace sub_mul_action
section has_smul
variables [has_smul R M]
variables (p : sub_mul_action R M)
variables {r : R} {x : M}
lemma smul_mem (r : R) (h : x ∈ p) : r • x ∈ p := p.smul_mem' r h
instance : has_smul R p :=
{ smul := λ c x, ⟨c • x.1, smul_mem _ c x.2⟩ }
variables {p}
@[simp, norm_cast] lemma coe_smul (r : R) (x : p) : ((r • x : p) : M) = r • ↑x := rfl
@[simp, norm_cast] lemma coe_mk (x : M) (hx : x ∈ p) : ((⟨x, hx⟩ : p) : M) = x := rfl
variables (p)
/-- Embedding of a submodule `p` to the ambient space `M`. -/
protected def subtype : p →[R] M :=
by refine {to_fun := coe, ..}; simp [coe_smul]
@[simp] theorem subtype_apply (x : p) : p.subtype x = x := rfl
lemma subtype_eq_val : ((sub_mul_action.subtype p) : p → M) = subtype.val := rfl
end has_smul
section mul_action_monoid
variables [monoid R] [mul_action R M]
section
variables [has_smul S R] [has_smul S M] [is_scalar_tower S R M]
variables (p : sub_mul_action R M)
lemma smul_of_tower_mem (s : S) {x : M} (h : x ∈ p) : s • x ∈ p :=
by { rw [←one_smul R x, ←smul_assoc], exact p.smul_mem _ h }
instance has_smul' : has_smul S p :=
{ smul := λ c x, ⟨c • x.1, smul_of_tower_mem _ c x.2⟩ }
instance : is_scalar_tower S R p :=
{ smul_assoc := λ s r x, subtype.ext $ smul_assoc s r ↑x }
@[simp, norm_cast] lemma coe_smul_of_tower (s : S) (x : p) : ((s • x : p) : M) = s • ↑x := rfl
@[simp] lemma smul_mem_iff' {G} [group G] [has_smul G R] [mul_action G M]
[is_scalar_tower G R M] (g : G) {x : M} :
g • x ∈ p ↔ x ∈ p :=
⟨λ h, inv_smul_smul g x ▸ p.smul_of_tower_mem g⁻¹ h, p.smul_of_tower_mem g⟩
instance [has_smul Sᵐᵒᵖ R] [has_smul Sᵐᵒᵖ M] [is_scalar_tower Sᵐᵒᵖ R M]
[is_central_scalar S M] : is_central_scalar S p :=
{ op_smul_eq_smul := λ r x, subtype.ext $ op_smul_eq_smul r x }
end
section
variables [monoid S] [has_smul S R] [mul_action S M] [is_scalar_tower S R M]
variables (p : sub_mul_action R M)
/-- If the scalar product forms a `mul_action`, then the subset inherits this action -/
instance mul_action' : mul_action S p :=
{ smul := (•),
one_smul := λ x, subtype.ext $ one_smul _ x,
mul_smul := λ c₁ c₂ x, subtype.ext $ mul_smul c₁ c₂ x }
instance : mul_action R p := p.mul_action'
end
/-- Orbits in a `sub_mul_action` coincide with orbits in the ambient space. -/
lemma coe_image_orbit {p : sub_mul_action R M} (m : p) :
coe '' mul_action.orbit R m = mul_action.orbit R (m : M) := (set.range_comp _ _).symm
/- -- Previously, the relatively useless :
lemma orbit_of_sub_mul {p : sub_mul_action R M} (m : p) :
(mul_action.orbit R m : set M) = mul_action.orbit R (m : M) := rfl
-/
/-- Stabilizers in monoid sub_mul_action coincide with stabilizers in the ambient space -/
lemma stabilizer_of_sub_mul.submonoid {p : sub_mul_action R M} (m : p) :
mul_action.stabilizer.submonoid R m = mul_action.stabilizer.submonoid R (m : M) :=
begin
ext,
simp only [mul_action.mem_stabilizer_submonoid_iff,
← sub_mul_action.coe_smul, set_like.coe_eq_coe]
end
end mul_action_monoid
section mul_action_group
variables [group R] [mul_action R M]
/-- Stabilizers in group sub_mul_action coincide with stabilizers in the ambient space -/
lemma stabilizer_of_sub_mul {p : sub_mul_action R M} (m : p) :
mul_action.stabilizer R m = mul_action.stabilizer R (m : M) :=
begin
rw ← subgroup.to_submonoid_eq,
exact stabilizer_of_sub_mul.submonoid m,
end
end mul_action_group
section module
variables [semiring R] [add_comm_monoid M]
variables [module R M]
variables (p : sub_mul_action R M)
lemma zero_mem (h : (p : set M).nonempty) : (0 : M) ∈ p :=
let ⟨x, hx⟩ := h in zero_smul R (x : M) ▸ p.smul_mem 0 hx
/-- If the scalar product forms a `module`, and the `sub_mul_action` is not `⊥`, then the
subset inherits the zero. -/
instance [n_empty : nonempty p] : has_zero p :=
{ zero := ⟨0, n_empty.elim $ λ x, p.zero_mem ⟨x, x.prop⟩⟩ }
end module
section add_comm_group
variables [ring R] [add_comm_group M]
variables [module R M]
variables (p p' : sub_mul_action R M)
variables {r : R} {x y : M}
lemma neg_mem (hx : x ∈ p) : -x ∈ p := by { rw ← neg_one_smul R, exact p.smul_mem _ hx }
@[simp] lemma neg_mem_iff : -x ∈ p ↔ x ∈ p :=
⟨λ h, by { rw ←neg_neg x, exact neg_mem _ h}, neg_mem _⟩
instance : has_neg p := ⟨λx, ⟨-x.1, neg_mem _ x.2⟩⟩
@[simp, norm_cast] lemma coe_neg (x : p) : ((-x : p) : M) = -x := rfl
end add_comm_group
end sub_mul_action
namespace sub_mul_action
variables [group_with_zero S] [monoid R] [mul_action R M]
variables [has_smul S R] [mul_action S M] [is_scalar_tower S R M]
variables (p : sub_mul_action R M) {s : S} {x y : M}
theorem smul_mem_iff (s0 : s ≠ 0) : s • x ∈ p ↔ x ∈ p :=
p.smul_mem_iff' (units.mk0 s s0)
end sub_mul_action
|
f446ca8ec5b63f4c3b2716519adf77e25a655639 | a9d0fb7b0e4f802bd3857b803e6c5c23d87fef91 | /tests/lean/check2.lean | 3f2e5ca523042e0085233e91405de6f13b22f700 | [
"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 | 20 | lean | --
check eq.rec_on
|
10c9f52c9cce440b65c18d8c4ec07f4e5ae7ee76 | bb31430994044506fa42fd667e2d556327e18dfe | /src/analysis/convex/hull.lean | e31a5497a850453f9d0e78c41161cf8fd63ea001 | [
"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 | 7,084 | lean | /-
Copyright (c) 2020 Yury Kudriashov. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yury Kudriashov, Yaël Dillies
-/
import analysis.convex.basic
import order.closure
/-!
# Convex hull
This file defines the convex hull of a set `s` in a module. `convex_hull 𝕜 s` is the smallest convex
set containing `s`. In order theory speak, this is a closure operator.
## Implementation notes
`convex_hull` is defined as a closure operator. This gives access to the `closure_operator` API
while the impact on writing code is minimal as `convex_hull 𝕜 s` is automatically elaborated as
`⇑(convex_hull 𝕜) s`.
-/
open set
open_locale pointwise
variables {𝕜 E F : Type*}
section convex_hull
section ordered_semiring
variables [ordered_semiring 𝕜]
section add_comm_monoid
variables (𝕜) [add_comm_monoid E] [add_comm_monoid F] [module 𝕜 E] [module 𝕜 F]
/-- The convex hull of a set `s` is the minimal convex set that includes `s`. -/
def convex_hull : closure_operator (set E) :=
closure_operator.mk₃
(λ s, ⋂ (t : set E) (hst : s ⊆ t) (ht : convex 𝕜 t), t)
(convex 𝕜)
(λ s, set.subset_Inter (λ t, set.subset_Inter $ λ hst, set.subset_Inter $ λ ht, hst))
(λ s, convex_Inter $ λ t, convex_Inter $ λ ht, convex_Inter id)
(λ s t hst ht, set.Inter_subset_of_subset t $ set.Inter_subset_of_subset hst $
set.Inter_subset _ ht)
variables (s : set E)
lemma subset_convex_hull : s ⊆ convex_hull 𝕜 s := (convex_hull 𝕜).le_closure s
lemma convex_convex_hull : convex 𝕜 (convex_hull 𝕜 s) := closure_operator.closure_mem_mk₃ s
lemma convex_hull_eq_Inter : convex_hull 𝕜 s = ⋂ (t : set E) (hst : s ⊆ t) (ht : convex 𝕜 t), t :=
rfl
variables {𝕜 s} {t : set E} {x y : E}
lemma mem_convex_hull_iff : x ∈ convex_hull 𝕜 s ↔ ∀ t, s ⊆ t → convex 𝕜 t → x ∈ t :=
by simp_rw [convex_hull_eq_Inter, mem_Inter]
lemma convex_hull_min (hst : s ⊆ t) (ht : convex 𝕜 t) : convex_hull 𝕜 s ⊆ t :=
closure_operator.closure_le_mk₃_iff (show s ≤ t, from hst) ht
lemma convex.convex_hull_subset_iff (ht : convex 𝕜 t) : convex_hull 𝕜 s ⊆ t ↔ s ⊆ t :=
⟨(subset_convex_hull _ _).trans, λ h, convex_hull_min h ht⟩
@[mono] lemma convex_hull_mono (hst : s ⊆ t) : convex_hull 𝕜 s ⊆ convex_hull 𝕜 t :=
(convex_hull 𝕜).monotone hst
lemma convex.convex_hull_eq (hs : convex 𝕜 s) : convex_hull 𝕜 s = s :=
closure_operator.mem_mk₃_closed hs
@[simp] lemma convex_hull_univ : convex_hull 𝕜 (univ : set E) = univ :=
closure_operator.closure_top (convex_hull 𝕜)
@[simp] lemma convex_hull_empty : convex_hull 𝕜 (∅ : set E) = ∅ := convex_empty.convex_hull_eq
@[simp] lemma convex_hull_empty_iff : convex_hull 𝕜 s = ∅ ↔ s = ∅ :=
begin
split,
{ intro h,
rw [←set.subset_empty_iff, ←h],
exact subset_convex_hull 𝕜 _ },
{ rintro rfl,
exact convex_hull_empty }
end
@[simp] lemma convex_hull_nonempty_iff : (convex_hull 𝕜 s).nonempty ↔ s.nonempty :=
begin
rw [nonempty_iff_ne_empty, nonempty_iff_ne_empty, ne.def, ne.def],
exact not_congr convex_hull_empty_iff,
end
alias convex_hull_nonempty_iff ↔ _ set.nonempty.convex_hull
attribute [protected] set.nonempty.convex_hull
lemma segment_subset_convex_hull (hx : x ∈ s) (hy : y ∈ s) : segment 𝕜 x y ⊆ convex_hull 𝕜 s :=
(convex_convex_hull _ _).segment_subset (subset_convex_hull _ _ hx) (subset_convex_hull _ _ hy)
@[simp] lemma convex_hull_singleton (x : E) : convex_hull 𝕜 ({x} : set E) = {x} :=
(convex_singleton x).convex_hull_eq
@[simp] lemma convex_hull_pair (x y : E) : convex_hull 𝕜 {x, y} = segment 𝕜 x y :=
begin
refine (convex_hull_min _ $ convex_segment _ _).antisymm
(segment_subset_convex_hull (mem_insert _ _) $ mem_insert_of_mem _ $ mem_singleton _),
rw [insert_subset, singleton_subset_iff],
exact ⟨left_mem_segment _ _ _, right_mem_segment _ _ _⟩,
end
lemma convex_hull_convex_hull_union_left (s t : set E) :
convex_hull 𝕜 (convex_hull 𝕜 s ∪ t) = convex_hull 𝕜 (s ∪ t) :=
closure_operator.closure_sup_closure_left _ _ _
lemma convex_hull_convex_hull_union_right (s t : set E) :
convex_hull 𝕜 (s ∪ convex_hull 𝕜 t) = convex_hull 𝕜 (s ∪ t) :=
closure_operator.closure_sup_closure_right _ _ _
lemma convex.convex_remove_iff_not_mem_convex_hull_remove {s : set E} (hs : convex 𝕜 s) (x : E) :
convex 𝕜 (s \ {x}) ↔ x ∉ convex_hull 𝕜 (s \ {x}) :=
begin
split,
{ rintro hsx hx,
rw hsx.convex_hull_eq at hx,
exact hx.2 (mem_singleton _) },
rintro hx,
suffices h : s \ {x} = convex_hull 𝕜 (s \ {x}), { convert convex_convex_hull 𝕜 _ },
exact subset.antisymm (subset_convex_hull 𝕜 _) (λ y hy, ⟨convex_hull_min (diff_subset _ _) hs hy,
by { rintro (rfl : y = x), exact hx hy }⟩),
end
lemma is_linear_map.convex_hull_image {f : E → F} (hf : is_linear_map 𝕜 f) (s : set E) :
convex_hull 𝕜 (f '' s) = f '' convex_hull 𝕜 s :=
set.subset.antisymm (convex_hull_min (image_subset _ (subset_convex_hull 𝕜 s)) $
(convex_convex_hull 𝕜 s).is_linear_image hf)
(image_subset_iff.2 $ convex_hull_min
(image_subset_iff.1 $ subset_convex_hull 𝕜 _)
((convex_convex_hull 𝕜 _).is_linear_preimage hf))
lemma linear_map.convex_hull_image (f : E →ₗ[𝕜] F) (s : set E) :
convex_hull 𝕜 (f '' s) = f '' convex_hull 𝕜 s :=
f.is_linear.convex_hull_image s
end add_comm_monoid
end ordered_semiring
section ordered_comm_semiring
variables [ordered_comm_semiring 𝕜] [add_comm_monoid E] [module 𝕜 E]
lemma convex_hull_smul (a : 𝕜) (s : set E) : convex_hull 𝕜 (a • s) = a • convex_hull 𝕜 s :=
(linear_map.lsmul _ _ a).convex_hull_image _
end ordered_comm_semiring
section ordered_ring
variables [ordered_ring 𝕜]
section add_comm_group
variables [add_comm_group E] [add_comm_group F] [module 𝕜 E] [module 𝕜 F] (s : set E)
lemma affine_map.image_convex_hull (f : E →ᵃ[𝕜] F) :
f '' convex_hull 𝕜 s = convex_hull 𝕜 (f '' s) :=
begin
apply set.subset.antisymm,
{ rw set.image_subset_iff,
refine convex_hull_min _ ((convex_convex_hull 𝕜 (⇑f '' s)).affine_preimage f),
rw ← set.image_subset_iff,
exact subset_convex_hull 𝕜 (f '' s) },
{ exact convex_hull_min (set.image_subset _ (subset_convex_hull 𝕜 s))
((convex_convex_hull 𝕜 s).affine_image f) }
end
lemma convex_hull_subset_affine_span : convex_hull 𝕜 s ⊆ (affine_span 𝕜 s : set E) :=
convex_hull_min (subset_affine_span 𝕜 s) (affine_span 𝕜 s).convex
@[simp] lemma affine_span_convex_hull : affine_span 𝕜 (convex_hull 𝕜 s) = affine_span 𝕜 s :=
begin
refine le_antisymm _ (affine_span_mono 𝕜 (subset_convex_hull 𝕜 s)),
rw affine_span_le,
exact convex_hull_subset_affine_span s,
end
lemma convex_hull_neg (s : set E) : convex_hull 𝕜 (-s) = -convex_hull 𝕜 s :=
by { simp_rw ←image_neg, exact (affine_map.image_convex_hull _ $ -1).symm }
end add_comm_group
end ordered_ring
end convex_hull
|
53e482d0cc9b62df7b7198277a5f6ec48d85d688 | d5bef83c55d40cb88f9a01b755c882a93348a847 | /tests/lean/run/soundness.lean | 9fb8a97743887c281e071aa832cfe9d5c3dda1bb | [
"Apache-2.0"
] | permissive | urkud/lean | 587d78216e1f0c7f651566e9e92cf8ade285d58d | 3526539070ea6268df5dd373deeb3ac8b9621952 | refs/heads/master | 1,660,171,634,921 | 1,657,873,466,000 | 1,657,873,466,000 | 249,789,456 | 0 | 0 | Apache-2.0 | 1,585,075,263,000 | 1,585,075,263,000 | null | UTF-8 | Lean | false | false | 6,724 | lean | /-
Copyright (c) 2015 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
Define propositional calculus, valuation, provability, validity, prove soundness.
This file is based on Floris van Doorn Coq files.
Similar to soundness.lean, but defines Nc in Type.
The idea is to be able to prove soundness using recursive equations.
-/
open nat bool list decidable
attribute [reducible]
definition PropVar := nat
inductive PropF
| Var : PropVar → PropF
| Bot : PropF
| Conj : PropF → PropF → PropF
| Disj : PropF → PropF → PropF
| Impl : PropF → PropF → PropF
namespace PropF
notation `#`:max P:max := Var P
local notation A ∨ B := Disj A B
local notation A ∧ B := Conj A B
local infixr `⇒`:27 := Impl
notation `⊥` := Bot
def Neg (A) := A ⇒ ⊥
notation `~` A := Neg A
def Top := ~⊥
notation `⊤` := Top
def BiImpl (A B) := A ⇒ B ∧ B ⇒ A
infixr `⇔`:27 := BiImpl
def valuation := PropVar → bool
def TrueQ (v : valuation) : PropF → bool
| (# P) := v P
| ⊥ := ff
| (A ∨ B) := TrueQ A || TrueQ B
| (A ∧ B) := TrueQ A && TrueQ B
| (A ⇒ B) := bnot (TrueQ A) || TrueQ B
attribute [reducible]
def is_true (b : bool) := b = tt
-- the valuation v satisfies a list of PropF, if forall (A : PropF) in Γ,
-- (TrueQ v A) is tt (the Boolean true)
def Satisfies (v) (Γ : list PropF) := ∀ A, A ∈ Γ → is_true (TrueQ v A)
def Models (Γ A) := ∀ v, Satisfies v Γ → is_true (TrueQ v A)
infix `⊨`:80 := Models
def Valid (p) := [] ⊨ p
reserve infix ` ⊢ `:26
/- Provability -/
inductive Nc : list PropF → PropF → Type
infix ⊢ := Nc
| Nax : ∀ Γ A, A ∈ Γ → Γ ⊢ A
| ImpI : ∀ Γ A B, A::Γ ⊢ B → Γ ⊢ A ⇒ B
| ImpE : ∀ Γ A B, Γ ⊢ A ⇒ B → Γ ⊢ A → Γ ⊢ B
| BotC : ∀ Γ A, (~A)::Γ ⊢ ⊥ → Γ ⊢ A
| AndI : ∀ Γ A B, Γ ⊢ A → Γ ⊢ B → Γ ⊢ A ∧ B
| AndE₁ : ∀ Γ A B, Γ ⊢ A ∧ B → Γ ⊢ A
| AndE₂ : ∀ Γ A B, Γ ⊢ A ∧ B → Γ ⊢ B
| OrI₁ : ∀ Γ A B, Γ ⊢ A → Γ ⊢ A ∨ B
| OrI₂ : ∀ Γ A B, Γ ⊢ B → Γ ⊢ A ∨ B
| OrE : ∀ Γ A B C, Γ ⊢ A ∨ B → A::Γ ⊢ C → B::Γ ⊢ C → Γ ⊢ C
infix ⊢ := Nc
def Provable (A) := [] ⊢ A
def Prop_Soundness := ∀ A, Provable A → Valid A
def Prop_Completeness := ∀ A, Valid A → Provable A
open Nc
def weakening2 : ∀ {Γ A Δ}, Γ ⊢ A → Γ ⊆ Δ → Δ ⊢ A
| ._ ._ Δ (Nax Γ A Hin) Hs := Nax _ _ (Hs Hin)
| ._ .(A ⇒ B) Δ (ImpI Γ A B H) Hs := ImpI _ _ _ (weakening2 H (cons_subset_cons A Hs))
| ._ ._ Δ (ImpE Γ A B H₁ H₂) Hs := ImpE _ _ _ (weakening2 H₁ Hs) (weakening2 H₂ Hs)
| ._ ._ Δ (BotC Γ A H) Hs := BotC _ _ (weakening2 H (cons_subset_cons (~A) Hs))
| ._ .(A ∧ B) Δ (AndI Γ A B H₁ H₂) Hs := AndI _ _ _ (weakening2 H₁ Hs) (weakening2 H₂ Hs)
| ._ ._ Δ (AndE₁ Γ A B H) Hs := AndE₁ _ _ _ (weakening2 H Hs)
| ._ ._ Δ (AndE₂ Γ A B H) Hs := AndE₂ _ _ _ (weakening2 H Hs)
| ._ .(A ∨ B) Δ (OrI₁ Γ A B H) Hs := OrI₁ _ _ _ (weakening2 H Hs)
| ._ .(A ∨ B) Δ (OrI₂ Γ A B H) Hs := OrI₂ _ _ _ (weakening2 H Hs)
| ._ ._ Δ (OrE Γ A B C H₁ H₂ H₃) Hs :=
OrE _ _ _ _ (weakening2 H₁ Hs) (weakening2 H₂ (cons_subset_cons A Hs)) (weakening2 H₃ (cons_subset_cons B Hs))
def weakening : ∀ Γ Δ A, Γ ⊢ A → Γ++Δ ⊢ A :=
λ Γ Δ A H, weakening2 H (subset_append_left Γ Δ)
def deduction : ∀ Γ A B, Γ ⊢ A ⇒ B → A::Γ ⊢ B :=
λ Γ A B H, ImpE _ _ _ (weakening2 H (subset_cons A Γ)) (Nax _ _ (mem_cons_self A Γ))
def prov_impl : ∀ A B, Provable (A ⇒ B) → ∀ Γ, Γ ⊢ A → Γ ⊢ B :=
λ A B Hp Γ Ha,
have wHp : Γ ⊢ (A ⇒ B), from weakening _ _ _ Hp,
ImpE _ _ _ wHp Ha
lemma Satisfies_cons : ∀ {A Γ v}, Satisfies v Γ → is_true (TrueQ v A) → Satisfies v (A::Γ) :=
λ A Γ v s t B BinAG,
or.elim BinAG
(λ e : B = A, by rewrite e; exact t)
(λ i : B ∈ Γ, s _ i)
attribute [simp] is_true TrueQ
theorem Soundness_general {v : valuation} : ∀ {A Γ}, Γ ⊢ A → Satisfies v Γ → is_true (TrueQ v A)
| ._ ._ (Nax Γ A Hin) s := s _ Hin
| .(A ⇒ B) ._ (ImpI Γ A B H) s :=
by_cases
(λ t : is_true (TrueQ v A),
have Satisfies v (A::Γ), from Satisfies_cons s t,
have TrueQ v B = tt, from Soundness_general H this,
by simp[*])
(λ f : ¬ is_true (TrueQ v A),
have TrueQ v A = ff, by simp at f; simp[*],
have bnot (TrueQ v A) = tt, by simp[*],
by simp[*])
| ._ ._ (ImpE Γ A B H₁ H₂) s :=
have aux : TrueQ v A = tt, from Soundness_general H₂ s,
have bnot (TrueQ v A) || TrueQ v B = tt, from Soundness_general H₁ s,
by simp [aux] at this; simp[*]
| ._ ._ (BotC Γ A H) s := by_contradiction
(λ n : TrueQ v A ≠ tt,
have TrueQ v A = ff, by {simp at n; simp[*]},
have TrueQ v (~A) = tt, begin change (bnot (TrueQ v A) || ff = tt), simp[*] end,
have Satisfies v ((~A)::Γ), from Satisfies_cons s this,
have TrueQ v ⊥ = tt, from Soundness_general H this,
absurd this ff_ne_tt)
| .(A ∧ B) ._ (AndI Γ A B H₁ H₂) s :=
have TrueQ v A = tt, from Soundness_general H₁ s,
have TrueQ v B = tt, from Soundness_general H₂ s,
by simp[*]
| ._ ._ (AndE₁ Γ A B H) s :=
have TrueQ v (A ∧ B) = tt, from Soundness_general H s,
by simp [TrueQ] at this; simp [*, is_true]
| ._ ._ (AndE₂ Γ A B H) s :=
have TrueQ v (A ∧ B) = tt, from Soundness_general H s,
by simp at this; simp[*]
| .(A ∨ B) ._ (OrI₁ Γ A B H) s :=
have TrueQ v A = tt, from Soundness_general H s,
by simp[*]
| .(A ∨ B) ._ (OrI₂ Γ A B H) s :=
have TrueQ v B = tt, from Soundness_general H s,
by simp[*]
| ._ ._ (OrE Γ A B C H₁ H₂ H₃) s :=
have TrueQ v A || TrueQ v B = tt, from Soundness_general H₁ s,
have or (TrueQ v A = tt) (TrueQ v B = tt), by simp at this; simp[*],
or.elim this
(λ At,
have Satisfies v (A::Γ), from Satisfies_cons s At,
Soundness_general H₂ this)
(λ Bt,
have Satisfies v (B::Γ), from Satisfies_cons s Bt,
Soundness_general H₃ this)
theorem Soundness : Prop_Soundness :=
λ A H v s, Soundness_general H s
end PropF
|
db3cc677b74ac7960f0f82a768ebba5c8ba66c9c | 5ca7b1b12d14c4742e29366312ba2c2ef8201b21 | /src/game/intro.lean | c6f666e648e37d9938bed80a6797e39b4266bc82 | [
"Apache-2.0"
] | permissive | MatthiasHu/natural_number_game | 2e464482ef3001863430b0336133b6697b275ba3 | 2d764f72669ae30861f6a1057fce0257f3e466c4 | refs/heads/master | 1,609,719,110,419 | 1,576,345,737,000 | 1,576,345,737,000 | 240,296,314 | 0 | 0 | Apache-2.0 | 1,581,608,357,000 | 1,581,608,356,000 | null | UTF-8 | Lean | false | false | 3,789 | lean | /-
# The Natural Number Game, version 1.1beta
## By Kevin Buzzard and Mohammad Pedramfar.
# What is this game?
Welcome to the natural number game -- a part-book part-game which shows the power of induction.
Blue nodes on the graph are ones that you are ready to enter. Grey nodes you should stay away
from -- a grey node turns blue when *all* nodes above it are complete. Green nodes are completed.
In this game, you get own version of the natural numbers, called `mynat`, in a programming
language called Lean. Your version of the natural numbers satisfies something called
the principle of mathematical induction, and a couple
of other things too (Peano's axioms). Unfortunately, nobody has proved any theorems about these
natural numbers yet. For example, addition will be defined for you,
but nobody has proved that `x + y = y + x` yet. This is your job. You're going to
prove mathematical theorems using the Lean theorem prover. In other words, you're going to solve
levels in a computer game.
You're going to prove these theorems using *tactics*. The introductory world, Tutorial World,
will take you through some of these tactics. During your proofs, your "goal" (i.e. what you're
supposed to be proving) will be displayed with a `⊢` symbol in front of it. If the top
right hand box reports "Theorem Proved!", you have closed all the goals in the level
and can move on to the next level in the world you're in. When you've finished a world,
hit "main menu" in the top left to get back here.
# What's new?
Pretty much all the <= levels of inequality world. I've
<a href="https://github.com/ImperialCollegeLondon/natural_number_game/blob/master/src/game/world10/level18a.lean" target="blank">
written all the Lean code for "strictly less than"</a> but am really busy with real life right now.
In my dreams -- even/odd world. Feel free to fork and add your name to the list of authors.
Instructions on how to build new worlds is on <a href="https://github.com/mpedramfar/Lean-game-maker" target="blank">
Mohammad's Lean Game Maker site</a>. Any Imperial 1st year maths or JMC students -- do you want to help make
<a href="https://github.com/ImperialCollegeLondon/real-number-game" target="blank">the real number game</a> in Lean
so you can teach yourself and others how to prove $\operatorname{Sup}(X+Y)=\operatorname{Sup}(X)+\operatorname{Sup}(Y)$ *rigorously*? I've
<a href="https://github.com/ImperialCollegeLondon/real-number-game/blob/a420eecef62209b729c910c2170d1dd27b74bc9f/world_plans/supinf.lean#L188" target="blank">
done the Lean proof</a> and most of the tactics you need to know to understand the proof are the ones in the natural number game anyway.
# Thanks
Special thanks to Rob Lewis for tactic hackery, Bryan Gin-Ge Chen for
javascript hackery, Patrick Massot for his
<a href="https://github.com/leanprover-community/format_lean" target="blank">Lean to html formatter</a>,
Sian Carey for Power World,
and, last but not least, all the people who fed back comments, including
the 2019-20 Imperial College 1st year maths beta tester students, Marie-Amélie Lawn,
Toby Gee, Joseph Myers, and all the people who have been in touch
via the <a href="https://leanprover.zulipchat.com/" target="blank">Lean Zulip chat</a>
or the <a href="https://xenaproject.wordpress.com/" target="blank">Xena Project blog</a>
or via <a href="https://twitter.com/XenaProject" target="blank">Twitter</a>.
The natural number game is brought to you by the Xena project, a project based at Imperial College London
whose aim is to get mathematics undergraduates using computer theorem provers.
Lean is a computer theorem prover being developed at Microsoft Research.
Prove a theorem. Write a function. <a href="https://twitter.com/XenaProject" target="blank">@XenaProject</a>.
-/
|
251a474e8afb2ddaa052aec5a448358201a13d21 | 6432ea7a083ff6ba21ea17af9ee47b9c371760f7 | /tests/lean/scopedTokens.lean | 50856ae653960a3445517e0b9d4ef83fde8dff06 | [
"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 | 484 | lean | namespace Foo
scoped syntax "foo!" term:max : term
macro_rules
| `(foo! $x) => `($x + 1)
#check foo! 20
theorem ex1 : foo! 20 = 21 := rfl
end Foo
#check foo! 10 -- Error
def foo! := 10
theorem ex2 : foo! = 10 := rfl
#check foo!
open Foo
#check foo! 20
theorem ex3 : foo! 10 = 11 := rfl
namespace Bla
scoped syntax "bla!" term:max : term
macro_rules
| `(bla! $x) => `($x * 2)
theorem ex2 : bla! 3 = 6 := rfl
end Bla
def bla! := 20
theorem ex4 : bla! = 20 := rfl
|
1211dd7d1fe825551eb4ac16fd48601bb32ed17e | 1437b3495ef9020d5413178aa33c0a625f15f15f | /category_theory/products.lean | 1685ae716a118d448b978e06104ae25318c2a9b2 | [
"Apache-2.0"
] | permissive | jean002/mathlib | c66bbb2d9fdc9c03ae07f869acac7ddbfce67a30 | dc6c38a765799c99c4d9c8d5207d9e6c9e0e2cfd | refs/heads/master | 1,587,027,806,375 | 1,547,306,358,000 | 1,547,306,358,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 5,537 | 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
import category_theory.functor_category
import category_theory.isomorphism
import tactic.interactive
namespace category_theory
universes v₁ v₂ v₃ v₄ u₁ u₂ u₃ u₄ -- declare the `v`'s first; see `category_theory.category` for an explanation
section
variables (C : Type u₁) [𝒞 : category.{v₁} C] (D : Type u₂) [𝒟 : category.{v₂} D]
include 𝒞 𝒟
/--
`prod C D` gives the cartesian product of two categories.
-/
instance prod : category.{max v₁ v₂} (C × D) :=
{ hom := λ X Y, ((X.1) ⟶ (Y.1)) × ((X.2) ⟶ (Y.2)),
id := λ X, ⟨ 𝟙 (X.1), 𝟙 (X.2) ⟩,
comp := λ _ _ _ f g, (f.1 ≫ g.1, f.2 ≫ g.2) }
-- rfl lemmas for category.prod
@[simp] lemma prod_id (X : C) (Y : D) : 𝟙 (X, Y) = (𝟙 X, 𝟙 Y) := rfl
@[simp] lemma prod_comp {P Q R : C} {S T U : D} (f : (P, S) ⟶ (Q, T)) (g : (Q, T) ⟶ (R, U)) :
f ≫ g = (f.1 ≫ g.1, f.2 ≫ g.2) := rfl
@[simp] lemma prod_id_fst (X : prod C D) : _root_.prod.fst (𝟙 X) = 𝟙 X.fst := rfl
@[simp] lemma prod_id_snd (X : prod C D) : _root_.prod.snd (𝟙 X) = 𝟙 X.snd := rfl
@[simp] lemma prod_comp_fst {X Y Z : prod C D} (f : X ⟶ Y) (g : Y ⟶ Z) :
(f ≫ g).1 = f.1 ≫ g.1 := rfl
@[simp] lemma prod_comp_snd {X Y Z : prod C D} (f : X ⟶ Y) (g : Y ⟶ Z) :
(f ≫ g).2 = f.2 ≫ g.2 := rfl
end
section
variables (C : Type u₁) [𝒞 : category.{v₁} C] (D : Type u₁) [𝒟 : category.{v₁} D]
include 𝒞 𝒟
/--
`prod.category.uniform C D` is an additional instance specialised so both factors have the same universe levels. This helps typeclass resolution.
-/
instance uniform_prod : category (C × D) := category_theory.prod C D
end
-- Next we define the natural functors into and out of product categories. For now this doesn't address the universal properties.
namespace prod
variables (C : Type u₁) [𝒞 : category.{v₁} C] (D : Type u₂) [𝒟 : category.{v₂} D]
include 𝒞 𝒟
/-- `inl C Z` is the functor `X ↦ (X, Z)`. -/
def inl (Z : D) : C ⥤ (C × D) :=
{ obj := λ X, (X, Z),
map := λ X Y f, (f, 𝟙 Z) }
/-- `inr D Z` is the functor `X ↦ (Z, X)`. -/
def inr (Z : C) : D ⥤ (C × D) :=
{ obj := λ X, (Z, X),
map := λ X Y f, (𝟙 Z, f) }
/-- `fst` is the functor `(X, Y) ↦ X`. -/
def fst : (C × D) ⥤ C :=
{ obj := λ X, X.1,
map := λ X Y f, f.1 }
/-- `snd` is the functor `(X, Y) ↦ Y`. -/
def snd : (C × D) ⥤ D :=
{ obj := λ X, X.2,
map := λ X Y f, f.2 }
def swap : (C × D) ⥤ (D × C) :=
{ obj := λ X, (X.2, X.1),
map := λ _ _ f, (f.2, f.1) }
def symmetry : ((swap C D) ⋙ (swap D C)) ≅ (functor.id (C × D)) :=
{ hom :=
{ app := λ X, 𝟙 X,
naturality' := begin intros, erw [category.comp_id (C × D), category.id_comp (C × D)], dsimp [swap], simp, end },
inv :=
{ app := λ X, 𝟙 X,
naturality' := begin intros, erw [category.comp_id (C × D), category.id_comp (C × D)], dsimp [swap], simp, end } }
end prod
section
variables (C : Type u₁) [𝒞 : category.{v₁} C] (D : Type u₂) [𝒟 : category.{v₂} D]
include 𝒞 𝒟
@[simp] def evaluation : C ⥤ (C ⥤ D) ⥤ D :=
{ obj := λ X,
{ obj := λ F, F.obj X,
map := λ F G α, α.app X, },
map := λ X Y f,
{ app := λ F, F.map f,
naturality' := λ F G α, eq.symm (α.naturality f) },
map_comp' := λ X Y Z f g,
begin
ext, dsimp, rw functor.map_comp,
end }
@[simp] def evaluation_uncurried : (C × (C ⥤ D)) ⥤ D :=
{ obj := λ p, p.2.obj p.1,
map := λ x y f, (x.2.map f.1) ≫ (f.2.app y.1),
map_comp' := begin
intros X Y Z f g, cases g, cases f, cases Z, cases Y, cases X, dsimp at *, simp at *,
erw [←nat_trans.vcomp_app, nat_trans.naturality, category.assoc, nat_trans.naturality]
end }
end
variables {A : Type u₁} [𝒜 : category.{v₁} A]
{B : Type u₂} [ℬ : category.{v₂} B]
{C : Type u₃} [𝒞 : category.{v₃} C]
{D : Type u₄} [𝒟 : category.{v₄} D]
include 𝒜 ℬ 𝒞 𝒟
namespace functor
/-- The cartesian product of two functors. -/
def prod (F : A ⥤ B) (G : C ⥤ D) : (A × C) ⥤ (B × D) :=
{ obj := λ X, (F.obj X.1, G.obj X.2),
map := λ _ _ f, (F.map f.1, G.map f.2) }
/- Because of limitations in Lean 3's handling of notations, we do not setup a notation `F × G`.
You can use `F.prod G` as a "poor man's infix", or just write `functor.prod F G`. -/
@[simp] lemma prod_obj (F : A ⥤ B) (G : C ⥤ D) (a : A) (c : C) : (F.prod G).obj (a, c) = (F.obj a, G.obj c) := rfl
@[simp] lemma prod_map (F : A ⥤ B) (G : C ⥤ D) {a a' : A} {c c' : C} (f : (a, c) ⟶ (a', c')) : (F.prod G).map f = (F.map f.1, G.map f.2) := rfl
end functor
namespace nat_trans
/-- The cartesian product of two natural transformations. -/
def prod {F G : A ⥤ B} {H I : C ⥤ D} (α : F ⟹ G) (β : H ⟹ I) : F.prod H ⟹ G.prod I :=
{ app := λ X, (α.app X.1, β.app X.2),
naturality' := begin /- `obviously'` says: -/ intros, cases f, cases Y, cases X, dsimp at *, simp, split, rw naturality, rw naturality end }
/- Again, it is inadvisable in Lean 3 to setup a notation `α × β`; use instead `α.prod β` or `nat_trans.prod α β`. -/
@[simp] lemma prod_app {F G : A ⥤ B} {H I : C ⥤ D} (α : F ⟹ G) (β : H ⟹ I) (a : A) (c : C) :
(nat_trans.prod α β).app (a, c) = (α.app a, β.app c) := rfl
end nat_trans
end category_theory
|
5e2f6649ca94f437f65667ba870cb1629e6ca704 | cf39355caa609c0f33405126beee2739aa3cb77e | /tests/lean/run/1608.lean | 8416246b60b9282e934a18b749b07d80f76b4b97 | [
"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 | 216 | lean | example {α : Type} {a b : α} (h : ¬ (a = b)) : b ≠ a :=
by cc
example {α : Type} {a b : α} (h : ¬ (a = b)) : ¬ (b = a) :=
by cc
example {α : Type} {a b : α} (h : ¬ (a = b)) : b ≠ a :=
begin [smt] end
|
cf8eb8277fcc7750010b999c21e937154667295e | 9be442d9ec2fcf442516ed6e9e1660aa9071b7bd | /stage0/src/Lean/Data/Lsp/Internal.lean | d82a9dae579c4c741c0b778a4a004acdfe98978a | [
"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 | EdAyers/lean4 | 57ac632d6b0789cb91fab2170e8c9e40441221bd | 37ba0df5841bde51dbc2329da81ac23d4f6a4de4 | refs/heads/master | 1,676,463,245,298 | 1,660,619,433,000 | 1,660,619,433,000 | 183,433,437 | 1 | 0 | Apache-2.0 | 1,657,612,672,000 | 1,556,196,574,000 | Lean | UTF-8 | Lean | false | false | 3,038 | lean | /-
Copyright (c) 2022 Joscha Mennicken. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Joscha Mennicken
-/
import Lean.Expr
import Lean.Data.Lsp.Basic
/-! This file contains types for communication between the watchdog and the
workers. These messages are not visible externally to users of the LSP server.
-/
namespace Lean.Lsp
open Std
/-! Most reference-related types have custom FromJson/ToJson implementations to
reduce the size of the resulting JSON. -/
inductive RefIdent where
| const : Name → RefIdent
| fvar : FVarId → RefIdent
deriving BEq, Hashable, Inhabited
namespace RefIdent
def toString : RefIdent → String
| RefIdent.const n => s!"c:{n}"
| RefIdent.fvar id => s!"f:{id.name}"
def fromString (s : String) : Except String RefIdent := do
let sPrefix := s.take 2
let sName := s.drop 2
-- See `FromJson Name`
let name ← match sName with
| "[anonymous]" => pure Name.anonymous
| _ => match Syntax.decodeNameLit ("`" ++ sName) with
| some n => pure n
| none => throw s!"expected a Name, got {sName}"
match sPrefix with
| "c:" => return RefIdent.const name
| "f:" => return RefIdent.fvar <| FVarId.mk name
| _ => throw "string must start with 'c:' or 'f:'"
end RefIdent
structure RefInfo where
definition : Option Lsp.Range
usages : Array Lsp.Range
instance : ToJson RefInfo where
toJson i :=
let rangeToList (r : Lsp.Range) : List Nat :=
[r.start.line, r.start.character, r.end.line, r.end.character]
Json.mkObj [
("definition", toJson $ i.definition.map rangeToList),
("usages", toJson $ i.usages.map rangeToList)
]
instance : FromJson RefInfo where
fromJson? j := do
let listToRange (l : List Nat) : Except String Lsp.Range := match l with
| [sLine, sChar, eLine, eChar] => pure ⟨⟨sLine, sChar⟩, ⟨eLine, eChar⟩⟩
| _ => throw s!"Expected list of length 4, not {l.length}"
let definition ← j.getObjValAs? (Option $ List Nat) "definition"
let definition ← match definition with
| none => pure none
| some list => some <$> listToRange list
let usages ← j.getObjValAs? (Array $ List Nat) "usages"
let usages ← usages.mapM listToRange
pure { definition, usages }
/-- References from a single module/file -/
def ModuleRefs := HashMap RefIdent RefInfo
instance : ToJson ModuleRefs where
toJson m := Json.mkObj <| m.toList.map fun (ident, info) => (ident.toString, toJson info)
instance : FromJson ModuleRefs where
fromJson? j := do
let node ← j.getObj?
node.foldM (init := HashMap.empty) fun m k v =>
return m.insert (← RefIdent.fromString k) (← fromJson? v)
/-- `$/lean/ileanInfoUpdate` and `$/lean/ileanInfoFinal` watchdog<-worker notifications.
Contains the file's definitions and references. -/
structure LeanIleanInfoParams where
/-- Version of the file these references are from. -/
version : Nat
references : ModuleRefs
deriving FromJson, ToJson
end Lean.Lsp
|
dcdfeda1e8c11a5e35173c483eee8085d710e3ce | 624f6f2ae8b3b1adc5f8f67a365c51d5126be45a | /tests/compiler/phashmap2.lean | c924b1389b801b7d8b459d7ffba53442c1b03646 | [
"Apache-2.0"
] | permissive | mhuisi/lean4 | 28d35a4febc2e251c7f05492e13f3b05d6f9b7af | dda44bc47f3e5d024508060dac2bcb59fd12e4c0 | refs/heads/master | 1,621,225,489,283 | 1,585,142,689,000 | 1,585,142,689,000 | 250,590,438 | 0 | 2 | Apache-2.0 | 1,602,443,220,000 | 1,585,327,814,000 | C | UTF-8 | Lean | false | false | 1,569 | lean | import Init.Data.PersistentHashMap
import Init.Lean.Data.Format
open Lean PersistentHashMap
abbrev Map := PersistentHashMap Nat Nat
partial def formatMap : Node Nat Nat → Format
| Node.collision keys vals _ => Format.sbracket $
keys.size.fold
(fun i fmt =>
let k := keys.get! i;
let v := vals.get! i;
let p := if i > 0 then fmt ++ format "," ++ Format.line else fmt;
p ++ "c@" ++ Format.paren (format k ++ " => " ++ format v))
Format.nil
| Node.entries entries => Format.sbracket $
entries.size.fold
(fun i fmt =>
let entry := entries.get! i;
let p := if i > 0 then fmt ++ format "," ++ Format.line else fmt;
p ++
match entry with
| Entry.null => "<null>"
| Entry.ref node => formatMap node
| Entry.entry k v => Format.paren (format k ++ " => " ++ format v))
Format.nil
def main : IO Unit :=
do
let a : Array Nat := [1, 2, 3].toArray;
IO.println (a.indexOf 2);
let m : Map := PersistentHashMap.empty;
let m := m.insert 1 1;
let m := m.insert 33 2;
let m := m.insert 65 3;
-- IO.println (formatMap m.root);
IO.println m.stats;
let m := m.erase 33;
IO.println (m.find? 1);
IO.println (m.find? 33);
IO.println (m.find? 65);
IO.println m.stats;
let m := m.erase 1;
IO.println (m.find? 1);
IO.println (m.find? 33);
IO.println (m.find? 65);
IO.println m.stats;
let m := m.erase 1;
IO.println (m.find? 1);
IO.println (m.find? 33);
IO.println (m.find? 65);
let m := m.erase 65;
IO.println (m.find? 1);
IO.println (m.find? 33);
IO.println (m.find? 65);
IO.println m.stats
|
3b94a4904e7fbc4e461a630f6f5c726af6ae6d84 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/ring_theory/ideal/operations.lean | bc0a4c1cce3836170dc0fde18d0f7466f95b2c68 | [
"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 | 91,786 | 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.algebra.operations
import algebra.ring.equiv
import data.nat.choose.sum
import ring_theory.coprime.lemmas
import ring_theory.ideal.quotient
import ring_theory.non_zero_divisors
/-!
# More operations on modules and ideals
-/
universes u v w x
open_locale big_operators pointwise
namespace submodule
variables {R : Type u} {M : Type v} {F : Type*} {G : Type*}
section comm_semiring
variables [comm_semiring R] [add_comm_monoid M] [module R M]
open_locale pointwise
instance has_smul' : has_smul (ideal R) (submodule R M) :=
⟨submodule.map₂ (linear_map.lsmul R M)⟩
/-- This duplicates the global `smul_eq_mul`, but doesn't have to unfold anywhere near as much to
apply. -/
protected lemma _root_.ideal.smul_eq_mul (I J : ideal R) : I • J = I * J := rfl
/-- `N.annihilator` is the ideal of all elements `r : R` such that `r • N = 0`. -/
def annihilator (N : submodule R M) : ideal R :=
(linear_map.lsmul R N).ker
variables {I J : ideal R} {N P : submodule R M}
theorem mem_annihilator {r} : r ∈ N.annihilator ↔ ∀ n ∈ N, r • n = (0:M) :=
⟨λ hr n hn, congr_arg subtype.val (linear_map.ext_iff.1 (linear_map.mem_ker.1 hr) ⟨n, hn⟩),
λ h, linear_map.mem_ker.2 $ linear_map.ext $ λ n, subtype.eq $ h n.1 n.2⟩
theorem mem_annihilator' {r} : r ∈ N.annihilator ↔ N ≤ comap (r • (linear_map.id : M →ₗ[R] M)) ⊥ :=
mem_annihilator.trans ⟨λ H n hn, (mem_bot R).2 $ H n hn, λ H n hn, (mem_bot R).1 $ H hn⟩
lemma mem_annihilator_span (s : set M) (r : R) :
r ∈ (submodule.span R s).annihilator ↔ ∀ n : s, r • (n : M) = 0 :=
begin
rw submodule.mem_annihilator,
split,
{ intros h n, exact h _ (submodule.subset_span n.prop) },
{ intros h n hn,
apply submodule.span_induction hn,
{ intros x hx, exact h ⟨x, hx⟩ },
{ exact smul_zero _ },
{ intros x y hx hy, rw [smul_add, hx, hy, zero_add] },
{ intros a x hx, rw [smul_comm, hx, smul_zero] } }
end
lemma mem_annihilator_span_singleton (g : M) (r : R) :
r ∈ (submodule.span R ({g} : set M)).annihilator ↔ r • g = 0 :=
by simp [mem_annihilator_span]
theorem annihilator_bot : (⊥ : submodule R M).annihilator = ⊤ :=
(ideal.eq_top_iff_one _).2 $ mem_annihilator'.2 bot_le
theorem annihilator_eq_top_iff : N.annihilator = ⊤ ↔ N = ⊥ :=
⟨λ H, eq_bot_iff.2 $ λ (n:M) hn, (mem_bot R).2 $
one_smul R n ▸ mem_annihilator.1 ((ideal.eq_top_iff_one _).1 H) n hn,
λ H, H.symm ▸ annihilator_bot⟩
theorem annihilator_mono (h : N ≤ P) : P.annihilator ≤ N.annihilator :=
λ r hrp, mem_annihilator.2 $ λ n hn, mem_annihilator.1 hrp n $ h hn
theorem annihilator_supr (ι : Sort w) (f : ι → submodule R M) :
(annihilator ⨆ i, f i) = ⨅ i, annihilator (f i) :=
le_antisymm (le_infi $ λ i, annihilator_mono $ le_supr _ _)
(λ r H, mem_annihilator'.2 $ supr_le $ λ i,
have _ := (mem_infi _).1 H i, mem_annihilator'.1 this)
theorem smul_mem_smul {r} {n} (hr : r ∈ I) (hn : n ∈ N) : r • n ∈ I • N := apply_mem_map₂ _ hr hn
theorem smul_le {P : submodule R M} : I • N ≤ P ↔ ∀ (r ∈ I) (n ∈ N), r • n ∈ P := map₂_le
@[elab_as_eliminator]
theorem smul_induction_on {p : M → Prop} {x} (H : x ∈ I • N)
(Hb : ∀ (r ∈ I) (n ∈ N), p (r • n))
(H1 : ∀ x y, p x → p y → p (x + y)) : p x :=
begin
have H0 : p 0 := by simpa only [zero_smul] using Hb 0 I.zero_mem 0 N.zero_mem,
refine submodule.supr_induction _ H _ H0 H1,
rintros ⟨i, hi⟩ m ⟨j, hj, (rfl : i • _ = m) ⟩,
exact Hb _ hi _ hj,
end
theorem mem_smul_span_singleton {I : ideal R} {m : M} {x : M} :
x ∈ I • span R ({m} : set M) ↔ ∃ y ∈ I, y • m = x :=
⟨λ hx, smul_induction_on hx
(λ r hri n hnm,
let ⟨s, hs⟩ := mem_span_singleton.1 hnm in ⟨r * s, I.mul_mem_right _ hri, hs ▸ mul_smul r s m⟩)
(λ m1 m2 ⟨y1, hyi1, hy1⟩ ⟨y2, hyi2, hy2⟩,
⟨y1 + y2, I.add_mem hyi1 hyi2, by rw [add_smul, hy1, hy2]⟩),
λ ⟨y, hyi, hy⟩, hy ▸ smul_mem_smul hyi (subset_span $ set.mem_singleton m)⟩
theorem smul_le_right : I • N ≤ N :=
smul_le.2 $ λ r hr n, N.smul_mem r
theorem smul_mono (hij : I ≤ J) (hnp : N ≤ P) : I • N ≤ J • P := map₂_le_map₂ hij hnp
theorem smul_mono_left (h : I ≤ J) : I • N ≤ J • N := map₂_le_map₂_left h
theorem smul_mono_right (h : N ≤ P) : I • N ≤ I • P := map₂_le_map₂_right h
lemma map_le_smul_top (I : ideal R) (f : R →ₗ[R] M) :
submodule.map f I ≤ I • (⊤ : submodule R M) :=
begin
rintros _ ⟨y, hy, rfl⟩,
rw [← mul_one y, ← smul_eq_mul, f.map_smul],
exact smul_mem_smul hy mem_top
end
@[simp] theorem annihilator_smul (N : submodule R M) : annihilator N • N = ⊥ :=
eq_bot_iff.2 (smul_le.2 (λ r, mem_annihilator.1))
@[simp] theorem annihilator_mul (I : ideal R) : annihilator I * I = ⊥ :=
annihilator_smul I
@[simp] theorem mul_annihilator (I : ideal R) : I * annihilator I = ⊥ :=
by rw [mul_comm, annihilator_mul]
variables (I J N P)
@[simp] theorem smul_bot : I • (⊥ : submodule R M) = ⊥ := map₂_bot_right _ _
@[simp] theorem bot_smul : (⊥ : ideal R) • N = ⊥ := map₂_bot_left _ _
@[simp] theorem top_smul : (⊤ : ideal R) • N = N :=
le_antisymm smul_le_right $ λ r hri, one_smul R r ▸ smul_mem_smul mem_top hri
theorem smul_sup : I • (N ⊔ P) = I • N ⊔ I • P := map₂_sup_right _ _ _ _
theorem sup_smul : (I ⊔ J) • N = I • N ⊔ J • N := map₂_sup_left _ _ _ _
protected theorem smul_assoc : (I • J) • N = I • (J • N) :=
le_antisymm (smul_le.2 $ λ rs hrsij t htn,
smul_induction_on hrsij
(λ r hr s hs,
(@smul_eq_mul R _ r s).symm ▸ smul_smul r s t ▸ smul_mem_smul hr (smul_mem_smul hs htn))
(λ x y, (add_smul x y t).symm ▸ submodule.add_mem _))
(smul_le.2 $ λ r hr sn hsn,
suffices J • N ≤ submodule.comap (r • (linear_map.id : M →ₗ[R] M)) ((I • J) • N),
from this hsn,
smul_le.2 $ λ s hs n hn, show r • (s • n) ∈ (I • J) • N,
from mul_smul r s n ▸ smul_mem_smul (smul_mem_smul hr hs) hn)
lemma smul_inf_le (M₁ M₂ : submodule R M) : I • (M₁ ⊓ M₂) ≤ I • M₁ ⊓ I • M₂ :=
le_inf (submodule.smul_mono_right inf_le_left) (submodule.smul_mono_right inf_le_right)
lemma smul_supr {ι : Sort*} {I : ideal R} {t : ι → submodule R M} :
I • supr t = ⨆ i, I • t i :=
map₂_supr_right _ _ _
lemma smul_infi_le {ι : Sort*} {I : ideal R} {t : ι → submodule R M} :
I • infi t ≤ ⨅ i, I • t i :=
le_infi (λ i, smul_mono_right (infi_le _ _))
variables (S : set R) (T : set M)
theorem span_smul_span : (ideal.span S) • (span R T) =
span R (⋃ (s ∈ S) (t ∈ T), {s • t}) :=
(map₂_span_span _ _ _ _).trans $ congr_arg _ $ set.image2_eq_Union _ _ _
lemma ideal_span_singleton_smul (r : R) (N : submodule R M) :
(ideal.span {r} : ideal R) • N = r • N :=
begin
have : span R (⋃ (t : M) (x : t ∈ N), {r • t}) = r • N,
{ convert span_eq _, exact (set.image_eq_Union _ (N : set M)).symm },
conv_lhs { rw [← span_eq N, span_smul_span] },
simpa
end
lemma span_smul_eq (r : R) (s : set M) : span R (r • s) = r • span R s :=
by rw [← ideal_span_singleton_smul, span_smul_span, ←set.image2_eq_Union,
set.image2_singleton_left, set.image_smul]
lemma mem_of_span_top_of_smul_mem (M' : submodule R M)
(s : set R) (hs : ideal.span s = ⊤) (x : M) (H : ∀ r : s, (r : R) • x ∈ M') : x ∈ M' :=
begin
suffices : (⊤ : ideal R) • (span R ({x} : set M)) ≤ M',
{ rw top_smul at this, exact this (subset_span (set.mem_singleton x)) },
rw [← hs, span_smul_span, span_le],
simpa using H
end
/-- Given `s`, a generating set of `R`, to check that an `x : M` falls in a
submodule `M'` of `x`, we only need to show that `r ^ n • x ∈ M'` for some `n` for each `r : s`. -/
lemma mem_of_span_eq_top_of_smul_pow_mem (M' : submodule R M)
(s : set R) (hs : ideal.span s = ⊤) (x : M)
(H : ∀ r : s, ∃ (n : ℕ), (r ^ n : R) • x ∈ M') : x ∈ M' :=
begin
obtain ⟨s', hs₁, hs₂⟩ := (ideal.span_eq_top_iff_finite _).mp hs,
replace H : ∀ r : s', ∃ (n : ℕ), (r ^ n : R) • x ∈ M' := λ r, H ⟨_, hs₁ r.prop⟩,
choose n₁ n₂ using H,
let N := s'.attach.sup n₁,
have hs' := ideal.span_pow_eq_top (s' : set R) hs₂ N,
apply M'.mem_of_span_top_of_smul_mem _ hs',
rintro ⟨_, r, hr, rfl⟩,
convert M'.smul_mem (r ^ (N - n₁ ⟨r, hr⟩)) (n₂ ⟨r, hr⟩) using 1,
simp only [subtype.coe_mk, smul_smul, ← pow_add],
rw tsub_add_cancel_of_le (finset.le_sup (s'.mem_attach _) : n₁ ⟨r, hr⟩ ≤ N),
end
variables {M' : Type w} [add_comm_monoid M'] [module R M']
theorem map_smul'' (f : M →ₗ[R] M') : (I • N).map f = I • N.map f :=
le_antisymm (map_le_iff_le_comap.2 $ smul_le.2 $ λ r hr n hn, show f (r • n) ∈ I • N.map f,
from (f.map_smul r n).symm ▸ smul_mem_smul hr (mem_map_of_mem hn)) $
smul_le.2 $ λ r hr n hn, let ⟨p, hp, hfp⟩ := mem_map.1 hn in
hfp ▸ f.map_smul r p ▸ mem_map_of_mem (smul_mem_smul hr hp)
variables {I}
lemma mem_smul_span {s : set M} {x : M} :
x ∈ I • submodule.span R s ↔ x ∈ submodule.span R (⋃ (a ∈ I) (b ∈ s), ({a • b} : set M)) :=
by rw [← I.span_eq, submodule.span_smul_span, I.span_eq]; refl
variables (I)
/-- If `x` is an `I`-multiple of the submodule spanned by `f '' s`,
then we can write `x` as an `I`-linear combination of the elements of `f '' s`. -/
lemma mem_ideal_smul_span_iff_exists_sum {ι : Type*} (f : ι → M) (x : M) :
x ∈ I • span R (set.range f) ↔
∃ (a : ι →₀ R) (ha : ∀ i, a i ∈ I), a.sum (λ i c, c • f i) = x :=
begin
split, swap,
{ rintro ⟨a, ha, rfl⟩,
exact submodule.sum_mem _ (λ c _, smul_mem_smul (ha c) $ subset_span $ set.mem_range_self _) },
refine λ hx, span_induction (mem_smul_span.mp hx) _ _ _ _,
{ simp only [set.mem_Union, set.mem_range, set.mem_singleton_iff],
rintros x ⟨y, hy, x, ⟨i, rfl⟩, rfl⟩,
refine ⟨finsupp.single i y, λ j, _, _⟩,
{ letI := classical.dec_eq ι,
rw finsupp.single_apply, split_ifs, { assumption }, { exact I.zero_mem } },
refine @finsupp.sum_single_index ι R M _ _ i _ (λ i y, y • f i) _,
simp },
{ exact ⟨0, λ i, I.zero_mem, finsupp.sum_zero_index⟩ },
{ rintros x y ⟨ax, hax, rfl⟩ ⟨ay, hay, rfl⟩,
refine ⟨ax + ay, λ i, I.add_mem (hax i) (hay i), finsupp.sum_add_index _ _⟩;
intros; simp only [zero_smul, add_smul] },
{ rintros c x ⟨a, ha, rfl⟩,
refine ⟨c • a, λ i, I.mul_mem_left c (ha i), _⟩,
rw [finsupp.sum_smul_index, finsupp.smul_sum];
intros; simp only [zero_smul, mul_smul] },
end
theorem mem_ideal_smul_span_iff_exists_sum' {ι : Type*} (s : set ι) (f : ι → M) (x : M) :
x ∈ I • span R (f '' s) ↔
∃ (a : s →₀ R) (ha : ∀ i, a i ∈ I), a.sum (λ i c, c • f i) = x :=
by rw [← submodule.mem_ideal_smul_span_iff_exists_sum, ← set.image_eq_range]
@[simp] lemma smul_comap_le_comap_smul (f : M →ₗ[R] M') (S : submodule R M') (I : ideal R) :
I • S.comap f ≤ (I • S).comap f :=
begin
refine (submodule.smul_le.mpr (λ r hr x hx, _)),
rw [submodule.mem_comap] at ⊢ hx,
rw f.map_smul,
exact submodule.smul_mem_smul hr hx
end
end comm_semiring
section comm_ring
variables [comm_ring R] [add_comm_group M] [module R M]
variables {N N₁ N₂ P P₁ P₂ : submodule R M}
/-- `N.colon P` is the ideal of all elements `r : R` such that `r • P ⊆ N`. -/
def colon (N P : submodule R M) : ideal R :=
annihilator (P.map N.mkq)
theorem mem_colon {r} : r ∈ N.colon P ↔ ∀ p ∈ P, r • p ∈ N :=
mem_annihilator.trans ⟨λ H p hp, (quotient.mk_eq_zero N).1 (H (quotient.mk p) (mem_map_of_mem hp)),
λ H m ⟨p, hp, hpm⟩, hpm ▸ (N.mkq).map_smul r p ▸ (quotient.mk_eq_zero N).2 $ H p hp⟩
theorem mem_colon' {r} : r ∈ N.colon P ↔ P ≤ comap (r • (linear_map.id : M →ₗ[R] M)) N :=
mem_colon
theorem colon_mono (hn : N₁ ≤ N₂) (hp : P₁ ≤ P₂) : N₁.colon P₂ ≤ N₂.colon P₁ :=
λ r hrnp, mem_colon.2 $ λ p₁ hp₁, hn $ mem_colon.1 hrnp p₁ $ hp hp₁
theorem infi_colon_supr (ι₁ : Sort w) (f : ι₁ → submodule R M)
(ι₂ : Sort x) (g : ι₂ → submodule R M) :
(⨅ i, f i).colon (⨆ j, g j) = ⨅ i j, (f i).colon (g j) :=
le_antisymm (le_infi $ λ i, le_infi $ λ j, colon_mono (infi_le _ _) (le_supr _ _))
(λ r H, mem_colon'.2 $ supr_le $ λ j, map_le_iff_le_comap.1 $ le_infi $ λ i,
map_le_iff_le_comap.2 $ mem_colon'.1 $ have _ := ((mem_infi _).1 H i),
have _ := ((mem_infi _).1 this j), this)
end comm_ring
end submodule
namespace ideal
section add
variables {R : Type u} [semiring R]
@[simp] lemma add_eq_sup {I J : ideal R} : I + J = I ⊔ J := rfl
@[simp] lemma zero_eq_bot : (0 : ideal R) = ⊥ := rfl
end add
section mul_and_radical
variables {R : Type u} {ι : Type*} [comm_semiring R]
variables {I J K L : ideal R}
instance : has_mul (ideal R) := ⟨(•)⟩
@[simp] lemma one_eq_top : (1 : ideal R) = ⊤ :=
by erw [submodule.one_eq_range, linear_map.range_id]
theorem mul_mem_mul {r s} (hr : r ∈ I) (hs : s ∈ J) : r * s ∈ I * J :=
submodule.smul_mem_smul hr hs
theorem mul_mem_mul_rev {r s} (hr : r ∈ I) (hs : s ∈ J) : s * r ∈ I * J :=
mul_comm r s ▸ mul_mem_mul hr hs
lemma pow_mem_pow {x : R} (hx : x ∈ I) (n : ℕ) : x ^ n ∈ I ^ n :=
submodule.pow_mem_pow _ hx _
lemma prod_mem_prod {ι : Type*} {s : finset ι} {I : ι → ideal R} {x : ι → R} :
(∀ i ∈ s, x i ∈ I i) → ∏ i in s, x i ∈ ∏ i in s, I i :=
begin
classical,
apply finset.induction_on s,
{ intro _, rw [finset.prod_empty, finset.prod_empty, one_eq_top], exact submodule.mem_top },
{ intros a s ha IH h,
rw [finset.prod_insert ha, finset.prod_insert ha],
exact mul_mem_mul (h a $ finset.mem_insert_self a s)
(IH $ λ i hi, h i $ finset.mem_insert_of_mem hi) }
end
theorem mul_le : I * J ≤ K ↔ ∀ (r ∈ I) (s ∈ J), r * s ∈ K :=
submodule.smul_le
lemma mul_le_left : I * J ≤ J :=
ideal.mul_le.2 (λ r hr s, J.mul_mem_left _)
lemma mul_le_right : I * J ≤ I :=
ideal.mul_le.2 (λ r hr s hs, I.mul_mem_right _ hr)
@[simp] lemma sup_mul_right_self : I ⊔ (I * J) = I :=
sup_eq_left.2 ideal.mul_le_right
@[simp] lemma sup_mul_left_self : I ⊔ (J * I) = I :=
sup_eq_left.2 ideal.mul_le_left
@[simp] lemma mul_right_self_sup : (I * J) ⊔ I = I :=
sup_eq_right.2 ideal.mul_le_right
@[simp] lemma mul_left_self_sup : (J * I) ⊔ I = I :=
sup_eq_right.2 ideal.mul_le_left
variables (I J K)
protected theorem mul_comm : I * J = J * I :=
le_antisymm (mul_le.2 $ λ r hrI s hsJ, mul_mem_mul_rev hsJ hrI)
(mul_le.2 $ λ r hrJ s hsI, mul_mem_mul_rev hsI hrJ)
protected theorem mul_assoc : (I * J) * K = I * (J * K) :=
submodule.smul_assoc I J K
theorem span_mul_span (S T : set R) : span S * span T =
span ⋃ (s ∈ S) (t ∈ T), {s * t} :=
submodule.span_smul_span S T
variables {I J K}
lemma span_mul_span' (S T : set R) : span S * span T = span (S*T) :=
by { unfold span, rw submodule.span_mul_span, }
lemma span_singleton_mul_span_singleton (r s : R) :
span {r} * span {s} = (span {r * s} : ideal R) :=
by { unfold span, rw [submodule.span_mul_span, set.singleton_mul_singleton], }
lemma span_singleton_pow (s : R) (n : ℕ):
span {s} ^ n = (span {s ^ n} : ideal R) :=
begin
induction n with n ih, { simp [set.singleton_one], },
simp only [pow_succ, ih, span_singleton_mul_span_singleton],
end
lemma mem_mul_span_singleton {x y : R} {I : ideal R} :
x ∈ I * span {y} ↔ ∃ z ∈ I, z * y = x :=
submodule.mem_smul_span_singleton
lemma mem_span_singleton_mul {x y : R} {I : ideal R} :
x ∈ span {y} * I ↔ ∃ z ∈ I, y * z = x :=
by simp only [mul_comm, mem_mul_span_singleton]
lemma le_span_singleton_mul_iff {x : R} {I J : ideal R} :
I ≤ span {x} * J ↔ ∀ zI ∈ I, ∃ zJ ∈ J, x * zJ = zI :=
show (∀ {zI} (hzI : zI ∈ I), zI ∈ span {x} * J) ↔ ∀ zI ∈ I, ∃ zJ ∈ J, x * zJ = zI,
by simp only [mem_span_singleton_mul]
lemma span_singleton_mul_le_iff {x : R} {I J : ideal R} :
span {x} * I ≤ J ↔ ∀ z ∈ I, x * z ∈ J :=
begin
simp only [mul_le, mem_span_singleton_mul, mem_span_singleton],
split,
{ intros h zI hzI,
exact h x (dvd_refl x) zI hzI },
{ rintros h _ ⟨z, rfl⟩ zI hzI,
rw [mul_comm x z, mul_assoc],
exact J.mul_mem_left _ (h zI hzI) },
end
lemma span_singleton_mul_le_span_singleton_mul {x y : R} {I J : ideal R} :
span {x} * I ≤ span {y} * J ↔ ∀ zI ∈ I, ∃ zJ ∈ J, x * zI = y * zJ :=
by simp only [span_singleton_mul_le_iff, mem_span_singleton_mul, eq_comm]
lemma eq_span_singleton_mul {x : R} (I J : ideal R) :
I = span {x} * J ↔ ((∀ zI ∈ I, ∃ zJ ∈ J, x * zJ = zI) ∧ (∀ z ∈ J, x * z ∈ I)) :=
by simp only [le_antisymm_iff, le_span_singleton_mul_iff, span_singleton_mul_le_iff]
lemma span_singleton_mul_eq_span_singleton_mul {x y : R} (I J : ideal R) :
span {x} * I = span {y} * J ↔
((∀ zI ∈ I, ∃ zJ ∈ J, x * zI = y * zJ) ∧
(∀ zJ ∈ J, ∃ zI ∈ I, x * zI = y * zJ)) :=
by simp only [le_antisymm_iff, span_singleton_mul_le_span_singleton_mul, eq_comm]
lemma prod_span {ι : Type*} (s : finset ι) (I : ι → set R) :
(∏ i in s, ideal.span (I i)) = ideal.span (∏ i in s, I i) :=
submodule.prod_span s I
lemma prod_span_singleton {ι : Type*} (s : finset ι) (I : ι → R) :
(∏ i in s, ideal.span ({I i} : set R)) = ideal.span {∏ i in s, I i} :=
submodule.prod_span_singleton s I
lemma finset_inf_span_singleton {ι : Type*} (s : finset ι) (I : ι → R)
(hI : set.pairwise ↑s (is_coprime on I)) :
(s.inf $ λ i, ideal.span ({I i} : set R)) = ideal.span {∏ i in s, I i} :=
begin
ext x,
simp only [submodule.mem_finset_inf, ideal.mem_span_singleton],
exact ⟨finset.prod_dvd_of_coprime hI,
λ h i hi, (finset.dvd_prod_of_mem _ hi).trans h⟩
end
lemma infi_span_singleton {ι : Type*} [fintype ι] (I : ι → R)
(hI : ∀ i j (hij : i ≠ j), is_coprime (I i) (I j)):
(⨅ i, ideal.span ({I i} : set R)) = ideal.span {∏ i, I i} :=
begin
rw [← finset.inf_univ_eq_infi, finset_inf_span_singleton],
rwa [finset.coe_univ, set.pairwise_univ]
end
lemma sup_eq_top_iff_is_coprime {R : Type*} [comm_semiring R] (x y : R) :
span ({x} : set R) ⊔ span {y} = ⊤ ↔ is_coprime x y :=
begin
rw [eq_top_iff_one, submodule.mem_sup],
split,
{ rintro ⟨u, hu, v, hv, h1⟩,
rw mem_span_singleton' at hu hv,
rw [← hu.some_spec, ← hv.some_spec] at h1,
exact ⟨_, _, h1⟩ },
{ exact λ ⟨u, v, h1⟩,
⟨_, mem_span_singleton'.mpr ⟨_, rfl⟩, _, mem_span_singleton'.mpr ⟨_, rfl⟩, h1⟩ },
end
theorem mul_le_inf : I * J ≤ I ⊓ J :=
mul_le.2 $ λ r hri s hsj, ⟨I.mul_mem_right s hri, J.mul_mem_left r hsj⟩
theorem multiset_prod_le_inf {s : multiset (ideal R)} :
s.prod ≤ s.inf :=
begin
classical, refine s.induction_on _ _,
{ rw [multiset.inf_zero], exact le_top },
intros a s ih,
rw [multiset.prod_cons, multiset.inf_cons],
exact le_trans mul_le_inf (inf_le_inf le_rfl ih)
end
theorem prod_le_inf {s : finset ι} {f : ι → ideal R} : s.prod f ≤ s.inf f :=
multiset_prod_le_inf
theorem mul_eq_inf_of_coprime (h : I ⊔ J = ⊤) : I * J = I ⊓ J :=
le_antisymm mul_le_inf $ λ r ⟨hri, hrj⟩,
let ⟨s, hsi, t, htj, hst⟩ := submodule.mem_sup.1 ((eq_top_iff_one _).1 h) in
mul_one r ▸ hst ▸ (mul_add r s t).symm ▸ ideal.add_mem (I * J) (mul_mem_mul_rev hsi hrj)
(mul_mem_mul hri htj)
lemma sup_mul_eq_of_coprime_left (h : I ⊔ J = ⊤) : I ⊔ (J * K) = I ⊔ K :=
le_antisymm (sup_le_sup_left mul_le_left _) $ λ i hi,
begin
rw eq_top_iff_one at h, rw submodule.mem_sup at h hi ⊢,
obtain ⟨i1, hi1, j, hj, h⟩ := h, obtain ⟨i', hi', k, hk, hi⟩ := hi,
refine ⟨_, add_mem hi' (mul_mem_right k _ hi1), _, mul_mem_mul hj hk, _⟩,
rw [add_assoc, ← add_mul, h, one_mul, hi]
end
lemma sup_mul_eq_of_coprime_right (h : I ⊔ K = ⊤) : I ⊔ (J * K) = I ⊔ J :=
by { rw mul_comm, exact sup_mul_eq_of_coprime_left h }
lemma mul_sup_eq_of_coprime_left (h : I ⊔ J = ⊤) : (I * K) ⊔ J = K ⊔ J :=
by { rw sup_comm at h, rw [sup_comm, sup_mul_eq_of_coprime_left h, sup_comm] }
lemma mul_sup_eq_of_coprime_right (h : K ⊔ J = ⊤) : (I * K) ⊔ J = I ⊔ J :=
by { rw sup_comm at h, rw [sup_comm, sup_mul_eq_of_coprime_right h, sup_comm] }
lemma sup_prod_eq_top {s : finset ι} {J : ι → ideal R} (h : ∀ i, i ∈ s → I ⊔ J i = ⊤) :
I ⊔ ∏ i in s, J i = ⊤ :=
finset.prod_induction _ (λ J, I ⊔ J = ⊤) (λ J K hJ hK, (sup_mul_eq_of_coprime_left hJ).trans hK)
(by rw [one_eq_top, sup_top_eq]) h
lemma sup_infi_eq_top {s : finset ι} {J : ι → ideal R} (h : ∀ i, i ∈ s → I ⊔ J i = ⊤) :
I ⊔ (⨅ i ∈ s, J i) = ⊤ :=
eq_top_iff.mpr $ le_of_eq_of_le (sup_prod_eq_top h).symm $ sup_le_sup_left
(le_of_le_of_eq prod_le_inf $ finset.inf_eq_infi _ _) _
lemma prod_sup_eq_top {s : finset ι} {J : ι → ideal R} (h : ∀ i, i ∈ s → J i ⊔ I = ⊤) :
(∏ i in s, J i) ⊔ I = ⊤ :=
sup_comm.trans (sup_prod_eq_top $ λ i hi, sup_comm.trans $ h i hi)
lemma infi_sup_eq_top {s : finset ι} {J : ι → ideal R} (h : ∀ i, i ∈ s → J i ⊔ I = ⊤) :
(⨅ i ∈ s, J i) ⊔ I = ⊤ :=
sup_comm.trans (sup_infi_eq_top $ λ i hi, sup_comm.trans $ h i hi)
lemma sup_pow_eq_top {n : ℕ} (h : I ⊔ J = ⊤) : I ⊔ (J ^ n) = ⊤ :=
by { rw [← finset.card_range n, ← finset.prod_const], exact sup_prod_eq_top (λ _ _, h) }
lemma pow_sup_eq_top {n : ℕ} (h : I ⊔ J = ⊤) : (I ^ n) ⊔ J = ⊤ :=
by { rw [← finset.card_range n, ← finset.prod_const], exact prod_sup_eq_top (λ _ _, h) }
lemma pow_sup_pow_eq_top {m n : ℕ} (h : I ⊔ J = ⊤) : (I ^ m) ⊔ (J ^ n) = ⊤ :=
sup_pow_eq_top (pow_sup_eq_top h)
variables (I)
@[simp] theorem mul_bot : I * ⊥ = ⊥ :=
submodule.smul_bot I
@[simp] theorem bot_mul : ⊥ * I = ⊥ :=
submodule.bot_smul I
@[simp] theorem mul_top : I * ⊤ = I :=
ideal.mul_comm ⊤ I ▸ submodule.top_smul I
@[simp] theorem top_mul : ⊤ * I = I :=
submodule.top_smul I
variables {I}
theorem mul_mono (hik : I ≤ K) (hjl : J ≤ L) : I * J ≤ K * L :=
submodule.smul_mono hik hjl
theorem mul_mono_left (h : I ≤ J) : I * K ≤ J * K :=
submodule.smul_mono_left h
theorem mul_mono_right (h : J ≤ K) : I * J ≤ I * K :=
submodule.smul_mono_right h
variables (I J K)
theorem mul_sup : I * (J ⊔ K) = I * J ⊔ I * K :=
submodule.smul_sup I J K
theorem sup_mul : (I ⊔ J) * K = I * K ⊔ J * K :=
submodule.sup_smul I J K
variables {I J K}
lemma pow_le_pow {m n : ℕ} (h : m ≤ n) :
I^n ≤ I^m :=
begin
cases nat.exists_eq_add_of_le h with k hk,
rw [hk, pow_add],
exact le_trans (mul_le_inf) (inf_le_left)
end
lemma pow_le_self {n : ℕ} (hn : n ≠ 0) : I^n ≤ I :=
calc I^n ≤ I ^ 1 : pow_le_pow (nat.pos_of_ne_zero hn)
... = I : pow_one _
lemma pow_mono {I J : ideal R} (e : I ≤ J) (n : ℕ) : I ^ n ≤ J ^ n :=
begin
induction n,
{ rw [pow_zero, pow_zero], exact rfl.le },
{ rw [pow_succ, pow_succ], exact ideal.mul_mono e n_ih }
end
lemma mul_eq_bot {R : Type*} [comm_semiring R] [no_zero_divisors R] {I J : ideal R} :
I * J = ⊥ ↔ I = ⊥ ∨ J = ⊥ :=
⟨λ hij, or_iff_not_imp_left.mpr (λ I_ne_bot, J.eq_bot_iff.mpr (λ j hj,
let ⟨i, hi, ne0⟩ := I.ne_bot_iff.mp I_ne_bot in
or.resolve_left (mul_eq_zero.mp ((I * J).eq_bot_iff.mp hij _ (mul_mem_mul hi hj))) ne0)),
λ h, by cases h; rw [← ideal.mul_bot, h, ideal.mul_comm]⟩
instance {R : Type*} [comm_semiring R] [no_zero_divisors R] : no_zero_divisors (ideal R) :=
{ eq_zero_or_eq_zero_of_mul_eq_zero := λ I J, mul_eq_bot.1 }
/-- A product of ideals in an integral domain is zero if and only if one of the terms is zero. -/
lemma prod_eq_bot {R : Type*} [comm_ring R] [is_domain R]
{s : multiset (ideal R)} : s.prod = ⊥ ↔ ∃ I ∈ s, I = ⊥ :=
prod_zero_iff_exists_zero
/-- The radical of an ideal `I` consists of the elements `r` such that `r^n ∈ I` for some `n`. -/
def radical (I : ideal R) : ideal R :=
{ carrier := { r | ∃ n : ℕ, r ^ n ∈ I },
zero_mem' := ⟨1, (pow_one (0:R)).symm ▸ I.zero_mem⟩,
add_mem' := λ x y ⟨m, hxmi⟩ ⟨n, hyni⟩, ⟨m + n,
(add_pow x y (m + n)).symm ▸ I.sum_mem $
show ∀ c ∈ finset.range (nat.succ (m + n)),
x ^ c * y ^ (m + n - c) * (nat.choose (m + n) c) ∈ I,
from λ c hc, or.cases_on (le_total c m)
(λ hcm, I.mul_mem_right _ $ I.mul_mem_left _ $ nat.add_comm n m ▸
(add_tsub_assoc_of_le hcm n).symm ▸
(pow_add y n (m-c)).symm ▸ I.mul_mem_right _ hyni)
(λ hmc, I.mul_mem_right _ $ I.mul_mem_right _ $ add_tsub_cancel_of_le hmc ▸
(pow_add x m (c-m)).symm ▸ I.mul_mem_right _ hxmi)⟩,
smul_mem' := λ r s ⟨n, hsni⟩, ⟨n, (mul_pow r s n).symm ▸ I.mul_mem_left (r^n) hsni⟩ }
theorem le_radical : I ≤ radical I :=
λ r hri, ⟨1, (pow_one r).symm ▸ hri⟩
variables (R)
theorem radical_top : (radical ⊤ : ideal R) = ⊤ :=
(eq_top_iff_one _).2 ⟨0, submodule.mem_top⟩
variables {R}
theorem radical_mono (H : I ≤ J) : radical I ≤ radical J :=
λ r ⟨n, hrni⟩, ⟨n, H hrni⟩
variables (I)
@[simp] theorem radical_idem : radical (radical I) = radical I :=
le_antisymm (λ r ⟨n, k, hrnki⟩, ⟨n * k, (pow_mul r n k).symm ▸ hrnki⟩) le_radical
variables {I}
theorem radical_le_radical_iff : radical I ≤ radical J ↔ I ≤ radical J :=
⟨λ h, le_trans le_radical h, λ h, radical_idem J ▸ radical_mono h⟩
theorem radical_eq_top : radical I = ⊤ ↔ I = ⊤ :=
⟨λ h, (eq_top_iff_one _).2 $ let ⟨n, hn⟩ := (eq_top_iff_one _).1 h in
@one_pow R _ n ▸ hn, λ h, h.symm ▸ radical_top R⟩
theorem is_prime.radical (H : is_prime I) : radical I = I :=
le_antisymm (λ r ⟨n, hrni⟩, H.mem_of_pow_mem n hrni) le_radical
variables (I J)
theorem radical_sup : radical (I ⊔ J) = radical (radical I ⊔ radical J) :=
le_antisymm (radical_mono $ sup_le_sup le_radical le_radical) $
λ r ⟨n, hrnij⟩, let ⟨s, hs, t, ht, hst⟩ := submodule.mem_sup.1 hrnij in
@radical_idem _ _ (I ⊔ J) ▸ ⟨n, hst ▸ ideal.add_mem _
(radical_mono le_sup_left hs) (radical_mono le_sup_right ht)⟩
theorem radical_inf : radical (I ⊓ J) = radical I ⊓ radical J :=
le_antisymm (le_inf (radical_mono inf_le_left) (radical_mono inf_le_right))
(λ r ⟨⟨m, hrm⟩, ⟨n, hrn⟩⟩, ⟨m + n, (pow_add r m n).symm ▸ I.mul_mem_right _ hrm,
(pow_add r m n).symm ▸ J.mul_mem_left _ hrn⟩)
theorem radical_mul : radical (I * J) = radical I ⊓ radical J :=
le_antisymm (radical_inf I J ▸ radical_mono $ @mul_le_inf _ _ I J)
(λ r ⟨⟨m, hrm⟩, ⟨n, hrn⟩⟩, ⟨m + n, (pow_add r m n).symm ▸ mul_mem_mul hrm hrn⟩)
variables {I J}
theorem is_prime.radical_le_iff (hj : is_prime J) :
radical I ≤ J ↔ I ≤ J :=
⟨le_trans le_radical, λ hij r ⟨n, hrni⟩, hj.mem_of_pow_mem n $ hij hrni⟩
theorem radical_eq_Inf (I : ideal R) :
radical I = Inf { J : ideal R | I ≤ J ∧ is_prime J } :=
le_antisymm (le_Inf $ λ J hJ, hJ.2.radical_le_iff.2 hJ.1) $
λ r hr, classical.by_contradiction $ λ hri,
let ⟨m, (hrm : r ∉ radical m), him, hm⟩ := zorn_nonempty_partial_order₀
{K : ideal R | r ∉ radical K}
(λ c hc hcc y hyc, ⟨Sup c, λ ⟨n, hrnc⟩, let ⟨y, hyc, hrny⟩ :=
(submodule.mem_Sup_of_directed ⟨y, hyc⟩ hcc.directed_on).1 hrnc in hc hyc ⟨n, hrny⟩,
λ z, le_Sup⟩) I hri in
have ∀ x ∉ m, r ∈ radical (m ⊔ span {x}) := λ x hxm, classical.by_contradiction $ λ hrmx, hxm $
hm (m ⊔ span {x}) hrmx le_sup_left ▸ (le_sup_right : _ ≤ m ⊔ span {x})
(subset_span $ set.mem_singleton _),
have is_prime m, from ⟨by rintro rfl; rw radical_top at hrm; exact hrm trivial,
λ x y hxym, or_iff_not_imp_left.2 $ λ hxm, classical.by_contradiction $ λ hym,
let ⟨n, hrn⟩ := this _ hxm,
⟨p, hpm, q, hq, hpqrn⟩ := submodule.mem_sup.1 hrn,
⟨c, hcxq⟩ := mem_span_singleton'.1 hq in
let ⟨k, hrk⟩ := this _ hym,
⟨f, hfm, g, hg, hfgrk⟩ := submodule.mem_sup.1 hrk,
⟨d, hdyg⟩ := mem_span_singleton'.1 hg in
hrm ⟨n + k, by rw [pow_add, ← hpqrn, ← hcxq, ← hfgrk, ← hdyg, add_mul, mul_add (c*x),
mul_assoc c x (d*y), mul_left_comm x, ← mul_assoc];
refine m.add_mem (m.mul_mem_right _ hpm) (m.add_mem (m.mul_mem_left _ hfm)
(m.mul_mem_left _ hxym))⟩⟩,
hrm $ this.radical.symm ▸ (Inf_le ⟨him, this⟩ : Inf {J : ideal R | I ≤ J ∧ is_prime J} ≤ m) hr
@[simp] lemma radical_bot_of_is_domain {R : Type u} [comm_semiring R] [no_zero_divisors R] :
radical (⊥ : ideal R) = ⊥ :=
eq_bot_iff.2 (λ x hx, hx.rec_on (λ n hn, pow_eq_zero hn))
instance : comm_semiring (ideal R) := submodule.comm_semiring
variables (R)
theorem top_pow (n : ℕ) : (⊤ ^ n : ideal R) = ⊤ :=
nat.rec_on n one_eq_top $ λ n ih, by rw [pow_succ, ih, top_mul]
variables {R}
variables (I)
theorem radical_pow (n : ℕ) (H : n > 0) : radical (I^n) = radical I :=
nat.rec_on n (not.elim dec_trivial) (λ n ih H,
or.cases_on (lt_or_eq_of_le $ nat.le_of_lt_succ H)
(λ H, calc radical (I^(n+1))
= radical I ⊓ radical (I^n) : by { rw pow_succ, exact radical_mul _ _ }
... = radical I ⊓ radical I : by rw ih H
... = radical I : inf_idem)
(λ H, H ▸ (pow_one I).symm ▸ rfl)) H
theorem is_prime.mul_le {I J P : ideal R} (hp : is_prime P) :
I * J ≤ P ↔ I ≤ P ∨ J ≤ P :=
⟨λ h, or_iff_not_imp_left.2 $ λ hip j hj, let ⟨i, hi, hip⟩ := set.not_subset.1 hip in
(hp.mem_or_mem $ h $ mul_mem_mul hi hj).resolve_left hip,
λ h, or.cases_on h (le_trans $ le_trans mul_le_inf inf_le_left)
(le_trans $ le_trans mul_le_inf inf_le_right)⟩
theorem is_prime.inf_le {I J P : ideal R} (hp : is_prime P) :
I ⊓ J ≤ P ↔ I ≤ P ∨ J ≤ P :=
⟨λ h, hp.mul_le.1 $ le_trans mul_le_inf h,
λ h, or.cases_on h (le_trans inf_le_left) (le_trans inf_le_right)⟩
theorem is_prime.multiset_prod_le {s : multiset (ideal R)} {P : ideal R}
(hp : is_prime P) (hne : s ≠ 0) :
s.prod ≤ P ↔ ∃ I ∈ s, I ≤ P :=
suffices s.prod ≤ P → ∃ I ∈ s, I ≤ P,
from ⟨this, λ ⟨i, his, hip⟩, le_trans multiset_prod_le_inf $
le_trans (multiset.inf_le his) hip⟩,
begin
classical,
obtain ⟨b, hb⟩ : ∃ b, b ∈ s := multiset.exists_mem_of_ne_zero hne,
obtain ⟨t, rfl⟩ : ∃ t, s = b ::ₘ t,
from ⟨s.erase b, (multiset.cons_erase hb).symm⟩,
refine t.induction_on _ _,
{ simp only [exists_prop, multiset.cons_zero, multiset.prod_singleton,
multiset.mem_singleton, exists_eq_left, imp_self] },
intros a s ih h,
rw [multiset.cons_swap, multiset.prod_cons, hp.mul_le] at h,
rw multiset.cons_swap,
cases h,
{ exact ⟨a, multiset.mem_cons_self a _, h⟩ },
obtain ⟨I, hI, ih⟩ : ∃ I ∈ b ::ₘ s, I ≤ P := ih h,
exact ⟨I, multiset.mem_cons_of_mem hI, ih⟩
end
theorem is_prime.multiset_prod_map_le {s : multiset ι} (f : ι → ideal R) {P : ideal R}
(hp : is_prime P) (hne : s ≠ 0) :
(s.map f).prod ≤ P ↔ ∃ i ∈ s, f i ≤ P :=
begin
rw hp.multiset_prod_le (mt multiset.map_eq_zero.mp hne),
simp_rw [exists_prop, multiset.mem_map, exists_exists_and_eq_and],
end
theorem is_prime.prod_le {s : finset ι} {f : ι → ideal R} {P : ideal R}
(hp : is_prime P) (hne : s.nonempty) :
s.prod f ≤ P ↔ ∃ i ∈ s, f i ≤ P :=
hp.multiset_prod_map_le f (mt finset.val_eq_zero.mp hne.ne_empty)
theorem is_prime.inf_le' {s : finset ι} {f : ι → ideal R} {P : ideal R} (hp : is_prime P)
(hsne: s.nonempty) :
s.inf f ≤ P ↔ ∃ i ∈ s, f i ≤ P :=
⟨λ h, (hp.prod_le hsne).1 $ le_trans prod_le_inf h,
λ ⟨i, his, hip⟩, le_trans (finset.inf_le his) hip⟩
theorem subset_union {R : Type u} [ring R] {I J K : ideal R} :
(I : set R) ⊆ J ∪ K ↔ I ≤ J ∨ I ≤ K :=
⟨λ h, or_iff_not_imp_left.2 $ λ hij s hsi,
let ⟨r, hri, hrj⟩ := set.not_subset.1 hij in classical.by_contradiction $ λ hsk,
or.cases_on (h $ I.add_mem hri hsi)
(λ hj, hrj $ add_sub_cancel r s ▸ J.sub_mem hj ((h hsi).resolve_right hsk))
(λ hk, hsk $ add_sub_cancel' r s ▸ K.sub_mem hk ((h hri).resolve_left hrj)),
λ h, or.cases_on h (λ h, set.subset.trans h $ set.subset_union_left J K)
(λ h, set.subset.trans h $ set.subset_union_right J K)⟩
theorem subset_union_prime' {R : Type u} [comm_ring R] {s : finset ι} {f : ι → ideal R} {a b : ι}
(hp : ∀ i ∈ s, is_prime (f i)) {I : ideal R} :
(I : set R) ⊆ f a ∪ f b ∪ (⋃ i ∈ (↑s : set ι), f i) ↔ I ≤ f a ∨ I ≤ f b ∨ ∃ i ∈ s, I ≤ f i :=
suffices (I : set R) ⊆ f a ∪ f b ∪ (⋃ i ∈ (↑s : set ι), f i) →
I ≤ f a ∨ I ≤ f b ∨ ∃ i ∈ s, I ≤ f i,
from ⟨this, λ h, or.cases_on h (λ h, set.subset.trans h $ set.subset.trans
(set.subset_union_left _ _) (set.subset_union_left _ _)) $
λ h, or.cases_on h (λ h, set.subset.trans h $ set.subset.trans
(set.subset_union_right _ _) (set.subset_union_left _ _)) $
λ ⟨i, his, hi⟩, by refine (set.subset.trans hi $ set.subset.trans _ $
set.subset_union_right _ _);
exact set.subset_bUnion_of_mem (finset.mem_coe.2 his)⟩,
begin
generalize hn : s.card = n, intros h,
unfreezingI { induction n with n ih generalizing a b s },
{ clear hp,
rw finset.card_eq_zero at hn, subst hn,
rw [finset.coe_empty, set.bUnion_empty, set.union_empty, subset_union] at h,
simpa only [exists_prop, finset.not_mem_empty, false_and, exists_false, or_false] },
classical,
replace hn : ∃ (i : ι) (t : finset ι), i ∉ t ∧ insert i t = s ∧ t.card = n :=
finset.card_eq_succ.1 hn,
unfreezingI { rcases hn with ⟨i, t, hit, rfl, hn⟩ },
replace hp : is_prime (f i) ∧ ∀ x ∈ t, is_prime (f x) := (t.forall_mem_insert _ _).1 hp,
by_cases Ht : ∃ j ∈ t, f j ≤ f i,
{ obtain ⟨j, hjt, hfji⟩ : ∃ j ∈ t, f j ≤ f i := Ht,
obtain ⟨u, hju, rfl⟩ : ∃ u, j ∉ u ∧ insert j u = t,
{ exact ⟨t.erase j, t.not_mem_erase j, finset.insert_erase hjt⟩ },
have hp' : ∀ k ∈ insert i u, is_prime (f k),
{ rw finset.forall_mem_insert at hp ⊢, exact ⟨hp.1, hp.2.2⟩ },
have hiu : i ∉ u := mt finset.mem_insert_of_mem hit,
have hn' : (insert i u).card = n,
{ rwa finset.card_insert_of_not_mem at hn ⊢, exacts [hiu, hju] },
have h' : (I : set R) ⊆ f a ∪ f b ∪ (⋃ k ∈ (↑(insert i u) : set ι), f k),
{ rw finset.coe_insert at h ⊢, rw finset.coe_insert at h,
simp only [set.bUnion_insert] at h ⊢,
rw [← set.union_assoc ↑(f i)] at h,
erw [set.union_eq_self_of_subset_right hfji] at h,
exact h },
specialize @ih a b (insert i u) hp' hn' h',
refine ih.imp id (or.imp id (exists_imp_exists $ λ k, _)), simp only [exists_prop],
exact and.imp (λ hk, finset.insert_subset_insert i (finset.subset_insert j u) hk) id },
by_cases Ha : f a ≤ f i,
{ have h' : (I : set R) ⊆ f i ∪ f b ∪ (⋃ j ∈ (↑t : set ι), f j),
{ rw [finset.coe_insert, set.bUnion_insert, ← set.union_assoc,
set.union_right_comm ↑(f a)] at h,
erw [set.union_eq_self_of_subset_left Ha] at h,
exact h },
specialize @ih i b t hp.2 hn h', right,
rcases ih with ih | ih | ⟨k, hkt, ih⟩,
{ exact or.inr ⟨i, finset.mem_insert_self i t, ih⟩ },
{ exact or.inl ih },
{ exact or.inr ⟨k, finset.mem_insert_of_mem hkt, ih⟩ } },
by_cases Hb : f b ≤ f i,
{ have h' : (I : set R) ⊆ f a ∪ f i ∪ (⋃ j ∈ (↑t : set ι), f j),
{ rw [finset.coe_insert, set.bUnion_insert, ← set.union_assoc, set.union_assoc ↑(f a)] at h,
erw [set.union_eq_self_of_subset_left Hb] at h,
exact h },
specialize @ih a i t hp.2 hn h',
rcases ih with ih | ih | ⟨k, hkt, ih⟩,
{ exact or.inl ih },
{ exact or.inr (or.inr ⟨i, finset.mem_insert_self i t, ih⟩) },
{ exact or.inr (or.inr ⟨k, finset.mem_insert_of_mem hkt, ih⟩) } },
by_cases Hi : I ≤ f i,
{ exact or.inr (or.inr ⟨i, finset.mem_insert_self i t, Hi⟩) },
have : ¬I ⊓ f a ⊓ f b ⊓ t.inf f ≤ f i,
{ rcases t.eq_empty_or_nonempty with (rfl | hsne),
{ rw [finset.inf_empty, inf_top_eq, hp.1.inf_le, hp.1.inf_le, not_or_distrib, not_or_distrib],
exact ⟨⟨Hi, Ha⟩, Hb⟩ },
simp only [hp.1.inf_le, hp.1.inf_le' hsne, not_or_distrib],
exact ⟨⟨⟨Hi, Ha⟩, Hb⟩, Ht⟩ },
rcases set.not_subset.1 this with ⟨r, ⟨⟨⟨hrI, hra⟩, hrb⟩, hr⟩, hri⟩,
by_cases HI : (I : set R) ⊆ f a ∪ f b ∪ ⋃ j ∈ (↑t : set ι), f j,
{ specialize ih hp.2 hn HI, rcases ih with ih | ih | ⟨k, hkt, ih⟩,
{ left, exact ih }, { right, left, exact ih },
{ right, right, exact ⟨k, finset.mem_insert_of_mem hkt, ih⟩ } },
exfalso, rcases set.not_subset.1 HI with ⟨s, hsI, hs⟩,
rw [finset.coe_insert, set.bUnion_insert] at h,
have hsi : s ∈ f i := ((h hsI).resolve_left (mt or.inl hs)).resolve_right (mt or.inr hs),
rcases h (I.add_mem hrI hsI) with ⟨ha | hb⟩ | hi | ht,
{ exact hs (or.inl $ or.inl $ add_sub_cancel' r s ▸ (f a).sub_mem ha hra) },
{ exact hs (or.inl $ or.inr $ add_sub_cancel' r s ▸ (f b).sub_mem hb hrb) },
{ exact hri (add_sub_cancel r s ▸ (f i).sub_mem hi hsi) },
{ rw set.mem_Union₂ at ht, rcases ht with ⟨j, hjt, hj⟩,
simp only [finset.inf_eq_infi, set_like.mem_coe, submodule.mem_infi] at hr,
exact hs (or.inr $ set.mem_bUnion hjt $ add_sub_cancel' r s ▸ (f j).sub_mem hj $ hr j hjt) }
end
/-- Prime avoidance. Atiyah-Macdonald 1.11, Eisenbud 3.3, Stacks 00DS, Matsumura Ex.1.6. -/
theorem subset_union_prime {R : Type u} [comm_ring R] {s : finset ι} {f : ι → ideal R} (a b : ι)
(hp : ∀ i ∈ s, i ≠ a → i ≠ b → is_prime (f i)) {I : ideal R} :
(I : set R) ⊆ (⋃ i ∈ (↑s : set ι), f i) ↔ ∃ i ∈ s, I ≤ f i :=
suffices (I : set R) ⊆ (⋃ i ∈ (↑s : set ι), f i) → ∃ i, i ∈ s ∧ I ≤ f i,
from ⟨λ h, bex_def.2 $ this h, λ ⟨i, his, hi⟩, set.subset.trans hi $ set.subset_bUnion_of_mem $
show i ∈ (↑s : set ι), from his⟩,
assume h : (I : set R) ⊆ (⋃ i ∈ (↑s : set ι), f i),
begin
classical,
by_cases has : a ∈ s,
{ unfreezingI { obtain ⟨t, hat, rfl⟩ : ∃ t, a ∉ t ∧ insert a t = s :=
⟨s.erase a, finset.not_mem_erase a s, finset.insert_erase has⟩ },
by_cases hbt : b ∈ t,
{ unfreezingI { obtain ⟨u, hbu, rfl⟩ : ∃ u, b ∉ u ∧ insert b u = t :=
⟨t.erase b, finset.not_mem_erase b t, finset.insert_erase hbt⟩ },
have hp' : ∀ i ∈ u, is_prime (f i),
{ intros i hiu, refine hp i (finset.mem_insert_of_mem (finset.mem_insert_of_mem hiu)) _ _;
unfreezingI { rintro rfl }; solve_by_elim only [finset.mem_insert_of_mem, *], },
rw [finset.coe_insert, finset.coe_insert, set.bUnion_insert, set.bUnion_insert,
← set.union_assoc, subset_union_prime' hp', bex_def] at h,
rwa [finset.exists_mem_insert, finset.exists_mem_insert] },
{ have hp' : ∀ j ∈ t, is_prime (f j),
{ intros j hj, refine hp j (finset.mem_insert_of_mem hj) _ _;
unfreezingI { rintro rfl }; solve_by_elim only [finset.mem_insert_of_mem, *], },
rw [finset.coe_insert, set.bUnion_insert, ← set.union_self (f a : set R),
subset_union_prime' hp', ← or_assoc, or_self, bex_def] at h,
rwa finset.exists_mem_insert } },
{ by_cases hbs : b ∈ s,
{ unfreezingI { obtain ⟨t, hbt, rfl⟩ : ∃ t, b ∉ t ∧ insert b t = s :=
⟨s.erase b, finset.not_mem_erase b s, finset.insert_erase hbs⟩ },
have hp' : ∀ j ∈ t, is_prime (f j),
{ intros j hj, refine hp j (finset.mem_insert_of_mem hj) _ _;
unfreezingI { rintro rfl }; solve_by_elim only [finset.mem_insert_of_mem, *], },
rw [finset.coe_insert, set.bUnion_insert, ← set.union_self (f b : set R),
subset_union_prime' hp', ← or_assoc, or_self, bex_def] at h,
rwa finset.exists_mem_insert },
cases s.eq_empty_or_nonempty with hse hsne,
{ substI hse, rw [finset.coe_empty, set.bUnion_empty, set.subset_empty_iff] at h,
have : (I : set R) ≠ ∅ := set.nonempty.ne_empty (set.nonempty_of_mem I.zero_mem),
exact absurd h this },
{ cases hsne.bex with i his,
unfreezingI { obtain ⟨t, hit, rfl⟩ : ∃ t, i ∉ t ∧ insert i t = s :=
⟨s.erase i, finset.not_mem_erase i s, finset.insert_erase his⟩ },
have hp' : ∀ j ∈ t, is_prime (f j),
{ intros j hj, refine hp j (finset.mem_insert_of_mem hj) _ _;
unfreezingI { rintro rfl }; solve_by_elim only [finset.mem_insert_of_mem, *], },
rw [finset.coe_insert, set.bUnion_insert, ← set.union_self (f i : set R),
subset_union_prime' hp', ← or_assoc, or_self, bex_def] at h,
rwa finset.exists_mem_insert } }
end
section dvd
/-- If `I` divides `J`, then `I` contains `J`.
In a Dedekind domain, to divide and contain are equivalent, see `ideal.dvd_iff_le`.
-/
lemma le_of_dvd {I J : ideal R} : I ∣ J → J ≤ I
| ⟨K, h⟩ := h.symm ▸ le_trans mul_le_inf inf_le_left
lemma is_unit_iff {I : ideal R} :
is_unit I ↔ I = ⊤ :=
is_unit_iff_dvd_one.trans ((@one_eq_top R _).symm ▸
⟨λ h, eq_top_iff.mpr (ideal.le_of_dvd h), λ h, ⟨⊤, by rw [mul_top, h]⟩⟩)
instance unique_units : unique ((ideal R)ˣ) :=
{ default := 1,
uniq := λ u, units.ext
(show (u : ideal R) = 1, by rw [is_unit_iff.mp u.is_unit, one_eq_top]) }
end dvd
end mul_and_radical
section map_and_comap
variables {R : Type u} {S : Type v}
section semiring
variables {F : Type*} [semiring R] [semiring S]
variables [rc : ring_hom_class F R S]
variables (f : F)
variables {I J : ideal R} {K L : ideal S}
include rc
/-- `I.map f` is the span of the image of the ideal `I` under `f`, which may be bigger than
the image itself. -/
def map (I : ideal R) : ideal S :=
span (f '' I)
/-- `I.comap f` is the preimage of `I` under `f`. -/
def comap (I : ideal S) : ideal R :=
{ carrier := f ⁻¹' I,
add_mem' := λ x y hx hy, by simp only [set.mem_preimage, set_like.mem_coe,
map_add, add_mem hx hy] at *,
zero_mem' := by simp only [set.mem_preimage, map_zero, set_like.mem_coe, submodule.zero_mem],
smul_mem' := λ c x hx, by { simp only [smul_eq_mul, set.mem_preimage, map_mul,
set_like.mem_coe] at *,
exact mul_mem_left I _ hx } }
variables {f}
theorem map_mono (h : I ≤ J) : map f I ≤ map f J :=
span_mono $ set.image_subset _ h
theorem mem_map_of_mem (f : F) {I : ideal R} {x : R} (h : x ∈ I) : f x ∈ map f I :=
subset_span ⟨x, h, rfl⟩
lemma apply_coe_mem_map (f : F) (I : ideal R) (x : I) : f x ∈ I.map f :=
mem_map_of_mem f x.prop
theorem map_le_iff_le_comap :
map f I ≤ K ↔ I ≤ comap f K :=
span_le.trans set.image_subset_iff
@[simp] theorem mem_comap {x} : x ∈ comap f K ↔ f x ∈ K := iff.rfl
theorem comap_mono (h : K ≤ L) : comap f K ≤ comap f L :=
set.preimage_mono (λ x hx, h hx)
variables (f)
theorem comap_ne_top (hK : K ≠ ⊤) : comap f K ≠ ⊤ :=
(ne_top_iff_one _).2 $ by rw [mem_comap, map_one];
exact (ne_top_iff_one _).1 hK
variables {G : Type*} [rcg : ring_hom_class G S R]
include rcg
lemma map_le_comap_of_inv_on (g : G) (I : ideal R) (hf : set.left_inv_on g f I) :
I.map f ≤ I.comap g :=
begin
refine ideal.span_le.2 _,
rintros x ⟨x, hx, rfl⟩,
rw [set_like.mem_coe, mem_comap, hf hx],
exact hx,
end
lemma comap_le_map_of_inv_on (g : G) (I : ideal S) (hf : set.left_inv_on g f (f ⁻¹' I)) :
I.comap f ≤ I.map g :=
λ x (hx : f x ∈ I), hf hx ▸ ideal.mem_map_of_mem g hx
/-- The `ideal` version of `set.image_subset_preimage_of_inverse`. -/
lemma map_le_comap_of_inverse (g : G) (I : ideal R) (h : function.left_inverse g f) :
I.map f ≤ I.comap g :=
map_le_comap_of_inv_on _ _ _ $ h.left_inv_on _
/-- The `ideal` version of `set.preimage_subset_image_of_inverse`. -/
lemma comap_le_map_of_inverse (g : G) (I : ideal S) (h : function.left_inverse g f) :
I.comap f ≤ I.map g :=
comap_le_map_of_inv_on _ _ _ $ h.left_inv_on _
omit rcg
instance is_prime.comap [hK : K.is_prime] : (comap f K).is_prime :=
⟨comap_ne_top _ hK.1, λ x y,
by simp only [mem_comap, map_mul]; apply hK.2⟩
variables (I J K L)
theorem map_top : map f ⊤ = ⊤ :=
(eq_top_iff_one _).2 $ subset_span ⟨1, trivial, map_one f⟩
variable (f)
lemma gc_map_comap : galois_connection (ideal.map f) (ideal.comap f) :=
λ I J, ideal.map_le_iff_le_comap
omit rc
@[simp] lemma comap_id : I.comap (ring_hom.id R) = I :=
ideal.ext $ λ _, iff.rfl
@[simp] lemma map_id : I.map (ring_hom.id R) = I :=
(gc_map_comap (ring_hom.id R)).l_unique galois_connection.id comap_id
lemma comap_comap {T : Type*} [semiring T] {I : ideal T} (f : R →+* S)
(g : S →+* T) : (I.comap g).comap f = I.comap (g.comp f) := rfl
lemma map_map {T : Type*} [semiring T] {I : ideal R} (f : R →+* S)
(g : S →+* T) : (I.map f).map g = I.map (g.comp f) :=
((gc_map_comap f).compose (gc_map_comap g)).l_unique
(gc_map_comap (g.comp f)) (λ _, comap_comap _ _)
include rc
lemma map_span (f : F) (s : set R) :
map f (span s) = span (f '' s) :=
symm $ submodule.span_eq_of_le _
(λ y ⟨x, hy, x_eq⟩, x_eq ▸ mem_map_of_mem f (subset_span hy))
(map_le_iff_le_comap.2 $ span_le.2 $ set.image_subset_iff.1 subset_span)
variables {f I J K L}
lemma map_le_of_le_comap : I ≤ K.comap f → I.map f ≤ K :=
(gc_map_comap f).l_le
lemma le_comap_of_map_le : I.map f ≤ K → I ≤ K.comap f :=
(gc_map_comap f).le_u
lemma le_comap_map : I ≤ (I.map f).comap f :=
(gc_map_comap f).le_u_l _
lemma map_comap_le : (K.comap f).map f ≤ K :=
(gc_map_comap f).l_u_le _
@[simp] lemma comap_top : (⊤ : ideal S).comap f = ⊤ :=
(gc_map_comap f).u_top
@[simp] lemma comap_eq_top_iff {I : ideal S} : I.comap f = ⊤ ↔ I = ⊤ :=
⟨ λ h, I.eq_top_iff_one.mpr (map_one f ▸ mem_comap.mp ((I.comap f).eq_top_iff_one.mp h)),
λ h, by rw [h, comap_top] ⟩
@[simp] lemma map_bot : (⊥ : ideal R).map f = ⊥ :=
(gc_map_comap f).l_bot
variables (f I J K L)
@[simp] lemma map_comap_map : ((I.map f).comap f).map f = I.map f :=
(gc_map_comap f).l_u_l_eq_l I
@[simp] lemma comap_map_comap : ((K.comap f).map f).comap f = K.comap f :=
(gc_map_comap f).u_l_u_eq_u K
lemma map_sup : (I ⊔ J).map f = I.map f ⊔ J.map f :=
(gc_map_comap f : galois_connection (map f) (comap f)).l_sup
theorem comap_inf : comap f (K ⊓ L) = comap f K ⊓ comap f L := rfl
variables {ι : Sort*}
lemma map_supr (K : ι → ideal R) : (supr K).map f = ⨆ i, (K i).map f :=
(gc_map_comap f : galois_connection (map f) (comap f)).l_supr
lemma comap_infi (K : ι → ideal S) : (infi K).comap f = ⨅ i, (K i).comap f :=
(gc_map_comap f : galois_connection (map f) (comap f)).u_infi
lemma map_Sup (s : set (ideal R)): (Sup s).map f = ⨆ I ∈ s, (I : ideal R).map f :=
(gc_map_comap f : galois_connection (map f) (comap f)).l_Sup
lemma comap_Inf (s : set (ideal S)): (Inf s).comap f = ⨅ I ∈ s, (I : ideal S).comap f :=
(gc_map_comap f : galois_connection (map f) (comap f)).u_Inf
lemma comap_Inf' (s : set (ideal S)) : (Inf s).comap f = ⨅ I ∈ (comap f '' s), I :=
trans (comap_Inf f s) (by rw infi_image)
theorem comap_is_prime [H : is_prime K] : is_prime (comap f K) :=
⟨comap_ne_top f H.ne_top,
λ x y h, H.mem_or_mem $ by rwa [mem_comap, map_mul] at h⟩
variables {I J K L}
theorem map_inf_le : map f (I ⊓ J) ≤ map f I ⊓ map f J :=
(gc_map_comap f : galois_connection (map f) (comap f)).monotone_l.map_inf_le _ _
theorem le_comap_sup : comap f K ⊔ comap f L ≤ comap f (K ⊔ L) :=
(gc_map_comap f : galois_connection (map f) (comap f)).monotone_u.le_map_sup _ _
omit rc
@[simp] lemma smul_top_eq_map {R S : Type*} [comm_semiring R] [comm_semiring S] [algebra R S]
(I : ideal R) : I • (⊤ : submodule R S) = (I.map (algebra_map R S)).restrict_scalars R :=
begin
refine le_antisymm (submodule.smul_le.mpr (λ r hr y _, _) )
(λ x hx, submodule.span_induction hx _ _ _ _),
{ rw algebra.smul_def,
exact mul_mem_right _ _ (mem_map_of_mem _ hr) },
{ rintros _ ⟨x, hx, rfl⟩,
rw [← mul_one (algebra_map R S x), ← algebra.smul_def],
exact submodule.smul_mem_smul hx submodule.mem_top },
{ exact submodule.zero_mem _ },
{ intros x y, exact submodule.add_mem _ },
intros a x hx,
refine submodule.smul_induction_on hx _ _,
{ intros r hr s hs,
rw smul_comm,
exact submodule.smul_mem_smul hr submodule.mem_top },
{ intros x y hx hy,
rw smul_add, exact submodule.add_mem _ hx hy },
end
@[simp] lemma coe_restrict_scalars {R S : Type*} [comm_semiring R] [semiring S] [algebra R S]
(I : ideal S) : ((I.restrict_scalars R) : set S) = ↑I :=
rfl
/-- The smallest `S`-submodule that contains all `x ∈ I * y ∈ J`
is also the smallest `R`-submodule that does so. -/
@[simp] lemma restrict_scalars_mul {R S : Type*} [comm_semiring R] [comm_semiring S] [algebra R S]
(I J : ideal S) : (I * J).restrict_scalars R = I.restrict_scalars R * J.restrict_scalars R :=
le_antisymm (λ x hx, submodule.mul_induction_on hx
(λ x hx y hy, submodule.mul_mem_mul hx hy)
(λ x y, submodule.add_mem _))
(submodule.mul_le.mpr (λ x hx y hy, ideal.mul_mem_mul hx hy))
section surjective
variables (hf : function.surjective f)
include hf
open function
theorem map_comap_of_surjective (I : ideal S) :
map f (comap f I) = I :=
le_antisymm (map_le_iff_le_comap.2 le_rfl)
(λ s hsi, let ⟨r, hfrs⟩ := hf s in
hfrs ▸ (mem_map_of_mem f $ show f r ∈ I, from hfrs.symm ▸ hsi))
/-- `map` and `comap` are adjoint, and the composition `map f ∘ comap f` is the
identity -/
def gi_map_comap : galois_insertion (map f) (comap f) :=
galois_insertion.monotone_intro
((gc_map_comap f).monotone_u)
((gc_map_comap f).monotone_l)
(λ _, le_comap_map)
(map_comap_of_surjective _ hf)
lemma map_surjective_of_surjective : surjective (map f) :=
(gi_map_comap f hf).l_surjective
lemma comap_injective_of_surjective : injective (comap f) :=
(gi_map_comap f hf).u_injective
lemma map_sup_comap_of_surjective (I J : ideal S) : (I.comap f ⊔ J.comap f).map f = I ⊔ J :=
(gi_map_comap f hf).l_sup_u _ _
lemma map_supr_comap_of_surjective (K : ι → ideal S) : (⨆i, (K i).comap f).map f = supr K :=
(gi_map_comap f hf).l_supr_u _
lemma map_inf_comap_of_surjective (I J : ideal S) : (I.comap f ⊓ J.comap f).map f = I ⊓ J :=
(gi_map_comap f hf).l_inf_u _ _
lemma map_infi_comap_of_surjective (K : ι → ideal S) : (⨅i, (K i).comap f).map f = infi K :=
(gi_map_comap f hf).l_infi_u _
theorem mem_image_of_mem_map_of_surjective {I : ideal R} {y}
(H : y ∈ map f I) : y ∈ f '' I :=
submodule.span_induction H (λ _, id) ⟨0, I.zero_mem, map_zero f⟩
(λ y1 y2 ⟨x1, hx1i, hxy1⟩ ⟨x2, hx2i, hxy2⟩,
⟨x1 + x2, I.add_mem hx1i hx2i, hxy1 ▸ hxy2 ▸ map_add f _ _⟩)
(λ c y ⟨x, hxi, hxy⟩,
let ⟨d, hdc⟩ := hf c in ⟨d * x, I.mul_mem_left _ hxi, hdc ▸ hxy ▸ map_mul f _ _⟩)
lemma mem_map_iff_of_surjective {I : ideal R} {y} :
y ∈ map f I ↔ ∃ x, x ∈ I ∧ f x = y :=
⟨λ h, (set.mem_image _ _ _).2 (mem_image_of_mem_map_of_surjective f hf h),
λ ⟨x, hx⟩, hx.right ▸ (mem_map_of_mem f hx.left)⟩
lemma le_map_of_comap_le_of_surjective : comap f K ≤ I → K ≤ map f I :=
λ h, (map_comap_of_surjective f hf K) ▸ map_mono h
end surjective
section injective
variables (hf : function.injective f)
include hf
lemma comap_bot_le_of_injective : comap f ⊥ ≤ I :=
begin
refine le_trans (λ x hx, _) bot_le,
rw [mem_comap, submodule.mem_bot, ← map_zero f] at hx,
exact eq.symm (hf hx) ▸ (submodule.zero_mem ⊥)
end
end injective
end semiring
section ring
variables {F : Type*} [ring R] [ring S]
variables [ring_hom_class F R S] (f : F) {I : ideal R}
section surjective
variables (hf : function.surjective f)
include hf
theorem comap_map_of_surjective (I : ideal R) : comap f (map f I) = I ⊔ comap f ⊥ :=
le_antisymm (assume r h, let ⟨s, hsi, hfsr⟩ := mem_image_of_mem_map_of_surjective f hf h in
submodule.mem_sup.2 ⟨s, hsi, r - s, (submodule.mem_bot S).2 $ by rw [map_sub, hfsr, sub_self],
add_sub_cancel'_right s r⟩)
(sup_le (map_le_iff_le_comap.1 le_rfl) (comap_mono bot_le))
/-- Correspondence theorem -/
def rel_iso_of_surjective : ideal S ≃o { p : ideal R // comap f ⊥ ≤ p } :=
{ to_fun := λ J, ⟨comap f J, comap_mono bot_le⟩,
inv_fun := λ I, map f I.1,
left_inv := λ J, map_comap_of_surjective f hf J,
right_inv := λ I, subtype.eq $ show comap f (map f I.1) = I.1,
from (comap_map_of_surjective f hf I).symm ▸ le_antisymm
(sup_le le_rfl I.2) le_sup_left,
map_rel_iff' := λ I1 I2, ⟨λ H, map_comap_of_surjective f hf I1 ▸
map_comap_of_surjective f hf I2 ▸ map_mono H, comap_mono⟩ }
/-- The map on ideals induced by a surjective map preserves inclusion. -/
def order_embedding_of_surjective : ideal S ↪o ideal R :=
(rel_iso_of_surjective f hf).to_rel_embedding.trans (subtype.rel_embedding _ _)
theorem map_eq_top_or_is_maximal_of_surjective {I : ideal R} (H : is_maximal I) :
(map f I) = ⊤ ∨ is_maximal (map f I) :=
begin
refine or_iff_not_imp_left.2 (λ ne_top, ⟨⟨λ h, ne_top h, λ J hJ, _⟩⟩),
{ refine (rel_iso_of_surjective f hf).injective
(subtype.ext_iff.2 (eq.trans (H.1.2 (comap f J) (lt_of_le_of_ne _ _)) comap_top.symm)),
{ exact (map_le_iff_le_comap).1 (le_of_lt hJ) },
{ exact λ h, hJ.right (le_map_of_comap_le_of_surjective f hf (le_of_eq h.symm)) } }
end
theorem comap_is_maximal_of_surjective {K : ideal S} [H : is_maximal K] : is_maximal (comap f K) :=
begin
refine ⟨⟨comap_ne_top _ H.1.1, λ J hJ, _⟩⟩,
suffices : map f J = ⊤,
{ replace this := congr_arg (comap f) this,
rw [comap_top, comap_map_of_surjective _ hf, eq_top_iff] at this,
rw eq_top_iff,
exact le_trans this (sup_le (le_of_eq rfl) (le_trans (comap_mono (bot_le)) (le_of_lt hJ))) },
refine H.1.2 (map f J) (lt_of_le_of_ne (le_map_of_comap_le_of_surjective _ hf (le_of_lt hJ))
(λ h, ne_of_lt hJ (trans (congr_arg (comap f) h) _))),
rw [comap_map_of_surjective _ hf, sup_eq_left],
exact le_trans (comap_mono bot_le) (le_of_lt hJ)
end
theorem comap_le_comap_iff_of_surjective (I J : ideal S) : comap f I ≤ comap f J ↔ I ≤ J :=
⟨λ h, (map_comap_of_surjective f hf I).symm.le.trans (map_le_of_le_comap h),
λ h, le_comap_of_map_le ((map_comap_of_surjective f hf I).le.trans h)⟩
end surjective
/-- If `f : R ≃+* S` is a ring isomorphism and `I : ideal R`, then `map f (map f.symm) = I`. -/
@[simp]
lemma map_of_equiv (I : ideal R) (f : R ≃+* S) : (I.map (f : R →+* S)).map (f.symm : S →+* R) = I :=
by simp [← ring_equiv.to_ring_hom_eq_coe, map_map]
/-- If `f : R ≃+* S` is a ring isomorphism and `I : ideal R`, then `comap f.symm (comap f) = I`. -/
@[simp]
lemma comap_of_equiv (I : ideal R) (f : R ≃+* S) :
(I.comap (f.symm : S →+* R)).comap (f : R →+* S) = I :=
by simp [← ring_equiv.to_ring_hom_eq_coe, comap_comap]
/-- If `f : R ≃+* S` is a ring isomorphism and `I : ideal R`, then `map f I = comap f.symm I`. -/
lemma map_comap_of_equiv (I : ideal R) (f : R ≃+* S) : I.map (f : R →+* S) = I.comap f.symm :=
le_antisymm (le_comap_of_map_le (map_of_equiv I f).le)
(le_map_of_comap_le_of_surjective _ f.surjective (comap_of_equiv I f).le)
section bijective
variables (hf : function.bijective f)
include hf
/-- Special case of the correspondence theorem for isomorphic rings -/
def rel_iso_of_bijective : ideal S ≃o ideal R :=
{ to_fun := comap f,
inv_fun := map f,
left_inv := (rel_iso_of_surjective f hf.right).left_inv,
right_inv := λ J, subtype.ext_iff.1
((rel_iso_of_surjective f hf.right).right_inv ⟨J, comap_bot_le_of_injective f hf.left⟩),
map_rel_iff' := λ _ _, (rel_iso_of_surjective f hf.right).map_rel_iff' }
lemma comap_le_iff_le_map {I : ideal R} {K : ideal S} : comap f K ≤ I ↔ K ≤ map f I :=
⟨λ h, le_map_of_comap_le_of_surjective f hf.right h,
λ h, ((rel_iso_of_bijective f hf).right_inv I) ▸ comap_mono h⟩
theorem map.is_maximal {I : ideal R} (H : is_maximal I) : is_maximal (map f I) :=
by refine or_iff_not_imp_left.1
(map_eq_top_or_is_maximal_of_surjective f hf.right H) (λ h, H.1.1 _);
calc I = comap f (map f I) : ((rel_iso_of_bijective f hf).right_inv I).symm
... = comap f ⊤ : by rw h
... = ⊤ : by rw comap_top
end bijective
lemma ring_equiv.bot_maximal_iff (e : R ≃+* S) :
(⊥ : ideal R).is_maximal ↔ (⊥ : ideal S).is_maximal :=
⟨λ h, (@map_bot _ _ _ _ _ _ e.to_ring_hom) ▸ map.is_maximal e.to_ring_hom e.bijective h,
λ h, (@map_bot _ _ _ _ _ _ e.symm.to_ring_hom) ▸ map.is_maximal e.symm.to_ring_hom
e.symm.bijective h⟩
end ring
section comm_ring
variables {F : Type*} [comm_ring R] [comm_ring S]
variables [rc : ring_hom_class F R S]
variables (f : F)
variables {I J : ideal R} {K L : ideal S}
variables (I J K L)
include rc
theorem map_mul : map f (I * J) = map f I * map f J :=
le_antisymm (map_le_iff_le_comap.2 $ mul_le.2 $ λ r hri s hsj,
show f (r * s) ∈ _, by rw map_mul;
exact mul_mem_mul (mem_map_of_mem f hri) (mem_map_of_mem f hsj))
(trans_rel_right _ (span_mul_span _ _) $ span_le.2 $
set.Union₂_subset $ λ i ⟨r, hri, hfri⟩,
set.Union₂_subset $ λ j ⟨s, hsj, hfsj⟩,
set.singleton_subset_iff.2 $ hfri ▸ hfsj ▸
by rw [← map_mul];
exact mem_map_of_mem f (mul_mem_mul hri hsj))
/-- The pushforward `ideal.map` as a monoid-with-zero homomorphism. -/
@[simps]
def map_hom : ideal R →*₀ ideal S :=
{ to_fun := map f,
map_mul' := λ I J, ideal.map_mul f I J,
map_one' := by convert ideal.map_top f; exact one_eq_top,
map_zero' := ideal.map_bot }
protected theorem map_pow (n : ℕ) : map f (I^n) = (map f I)^n :=
map_pow (map_hom f) I n
theorem comap_radical : comap f (radical K) = radical (comap f K) :=
le_antisymm (λ r ⟨n, hfrnk⟩, ⟨n, show f (r ^ n) ∈ K,
from (map_pow f r n).symm ▸ hfrnk⟩)
(λ r ⟨n, hfrnk⟩, ⟨n, map_pow f r n ▸ hfrnk⟩)
omit rc
@[simp] lemma map_quotient_self :
map (quotient.mk I) I = ⊥ :=
eq_bot_iff.2 $ ideal.map_le_iff_le_comap.2 $ λ x hx,
(submodule.mem_bot (R ⧸ I)).2 $ ideal.quotient.eq_zero_iff_mem.2 hx
variables {I J K L}
include rc
theorem map_radical_le : map f (radical I) ≤ radical (map f I) :=
map_le_iff_le_comap.2 $ λ r ⟨n, hrni⟩, ⟨n, map_pow f r n ▸ mem_map_of_mem f hrni⟩
theorem le_comap_mul : comap f K * comap f L ≤ comap f (K * L) :=
map_le_iff_le_comap.1 $ (map_mul f (comap f K) (comap f L)).symm ▸
mul_mono (map_le_iff_le_comap.2 $ le_rfl) (map_le_iff_le_comap.2 $ le_rfl)
lemma le_comap_pow (n : ℕ) :
(K.comap f) ^ n ≤ (K ^ n).comap f :=
begin
induction n,
{ rw [pow_zero, pow_zero, ideal.one_eq_top, ideal.one_eq_top], exact rfl.le },
{ rw [pow_succ, pow_succ], exact (ideal.mul_mono_right n_ih).trans (ideal.le_comap_mul f) }
end
omit rc
end comm_ring
end map_and_comap
section is_primary
variables {R : Type u} [comm_semiring R]
/-- A proper ideal `I` is primary iff `xy ∈ I` implies `x ∈ I` or `y ∈ radical I`. -/
def is_primary (I : ideal R) : Prop :=
I ≠ ⊤ ∧ ∀ {x y : R}, x * y ∈ I → x ∈ I ∨ y ∈ radical I
theorem is_prime.is_primary {I : ideal R} (hi : is_prime I) : is_primary I :=
⟨hi.1, λ x y hxy, (hi.mem_or_mem hxy).imp id $ λ hyi, le_radical hyi⟩
theorem mem_radical_of_pow_mem {I : ideal R} {x : R} {m : ℕ} (hx : x ^ m ∈ radical I) :
x ∈ radical I :=
radical_idem I ▸ ⟨m, hx⟩
theorem is_prime_radical {I : ideal R} (hi : is_primary I) : is_prime (radical I) :=
⟨mt radical_eq_top.1 hi.1, λ x y ⟨m, hxy⟩, begin
rw mul_pow at hxy, cases hi.2 hxy,
{ exact or.inl ⟨m, h⟩ },
{ exact or.inr (mem_radical_of_pow_mem h) }
end⟩
theorem is_primary_inf {I J : ideal R} (hi : is_primary I) (hj : is_primary J)
(hij : radical I = radical J) : is_primary (I ⊓ J) :=
⟨ne_of_lt $ lt_of_le_of_lt inf_le_left (lt_top_iff_ne_top.2 hi.1), λ x y ⟨hxyi, hxyj⟩,
begin
rw [radical_inf, hij, inf_idem],
cases hi.2 hxyi with hxi hyi, cases hj.2 hxyj with hxj hyj,
{ exact or.inl ⟨hxi, hxj⟩ },
{ exact or.inr hyj },
{ rw hij at hyi, exact or.inr hyi }
end⟩
end is_primary
section total
variables (ι : Type*)
variables (M : Type*) [add_comm_group M] {R : Type*} [comm_ring R] [module R M] (I : ideal R)
variables (v : ι → M) (hv : submodule.span R (set.range v) = ⊤)
open_locale big_operators
/-- A variant of `finsupp.total` that takes in vectors valued in `I`. -/
noncomputable
def finsupp_total : (ι →₀ I) →ₗ[R] M :=
(finsupp.total ι M R v).comp (finsupp.map_range.linear_map I.subtype)
variables {ι M v}
lemma finsupp_total_apply (f : ι →₀ I) :
finsupp_total ι M I v f = f.sum (λ i x, (x : R) • v i) :=
begin
dsimp [finsupp_total],
rw [finsupp.total_apply, finsupp.sum_map_range_index],
exact λ _, zero_smul _ _
end
lemma finsupp_total_apply_eq_of_fintype [fintype ι] (f : ι →₀ I) :
finsupp_total ι M I v f = ∑ i, (f i : R) • v i :=
by { rw [finsupp_total_apply, finsupp.sum_fintype], exact λ _, zero_smul _ _ }
lemma range_finsupp_total :
(finsupp_total ι M I v).range = I • (submodule.span R (set.range v)) :=
begin
ext,
rw submodule.mem_ideal_smul_span_iff_exists_sum,
refine ⟨λ ⟨f, h⟩, ⟨finsupp.map_range.linear_map I.subtype f, λ i, (f i).2, h⟩, _⟩,
rintro ⟨a, ha, rfl⟩,
classical,
refine ⟨a.map_range (λ r, if h : r ∈ I then ⟨r, h⟩ else 0) (by split_ifs; refl), _⟩,
rw [finsupp_total_apply, finsupp.sum_map_range_index],
{ apply finsupp.sum_congr, intros i _, rw dif_pos (ha i), refl },
{ exact λ _, zero_smul _ _ },
end
end total
end ideal
lemma associates.mk_ne_zero' {R : Type*} [comm_semiring R] {r : R} :
(associates.mk (ideal.span {r} : ideal R)) ≠ 0 ↔ (r ≠ 0):=
by rw [associates.mk_ne_zero, ideal.zero_eq_bot, ne.def, ideal.span_singleton_eq_bot]
namespace ring_hom
variables {R : Type u} {S : Type v} {T : Type v}
section semiring
variables {F : Type*} {G : Type*} [semiring R] [semiring S] [semiring T]
variables [rcf : ring_hom_class F R S] [rcg : ring_hom_class G T S]
(f : F) (g : G)
include rcf
/-- Kernel of a ring homomorphism as an ideal of the domain. -/
def ker : ideal R := ideal.comap f ⊥
/-- An element is in the kernel if and only if it maps to zero.-/
lemma mem_ker {r} : r ∈ ker f ↔ f r = 0 :=
by rw [ker, ideal.mem_comap, submodule.mem_bot]
lemma ker_eq : ((ker f) : set R) = set.preimage f {0} := rfl
lemma ker_eq_comap_bot (f : F) : ker f = ideal.comap f ⊥ := rfl
omit rcf
lemma comap_ker (f : S →+* R) (g : T →+* S) : f.ker.comap g = (f.comp g).ker :=
by rw [ring_hom.ker_eq_comap_bot, ideal.comap_comap, ring_hom.ker_eq_comap_bot]
include rcf
/-- If the target is not the zero ring, then one is not in the kernel.-/
lemma not_one_mem_ker [nontrivial S] (f : F) : (1:R) ∉ ker f :=
by { rw [mem_ker, map_one], exact one_ne_zero }
lemma ker_ne_top [nontrivial S] (f : F) : ker f ≠ ⊤ :=
(ideal.ne_top_iff_one _).mpr $ not_one_mem_ker f
omit rcf
end semiring
section ring
variables {F : Type*} [ring R] [semiring S] [rc : ring_hom_class F R S] (f : F)
include rc
lemma injective_iff_ker_eq_bot : function.injective f ↔ ker f = ⊥ :=
by { rw [set_like.ext'_iff, ker_eq, set.ext_iff], exact injective_iff_map_eq_zero' f }
lemma ker_eq_bot_iff_eq_zero : ker f = ⊥ ↔ ∀ x, f x = 0 → x = 0 :=
by { rw [← injective_iff_map_eq_zero f, injective_iff_ker_eq_bot] }
omit rc
@[simp] lemma ker_coe_equiv (f : R ≃+* S) :
ker (f : R →+* S) = ⊥ :=
by simpa only [←injective_iff_ker_eq_bot] using equiv_like.injective f
@[simp] lemma ker_equiv {F' : Type*} [ring_equiv_class F' R S] (f : F') :
ker f = ⊥ :=
by simpa only [←injective_iff_ker_eq_bot] using equiv_like.injective f
end ring
section comm_ring
variables [comm_ring R] [comm_ring S] (f : R →+* S)
/-- The induced map from the quotient by the kernel to the codomain.
This is an isomorphism if `f` has a right inverse (`quotient_ker_equiv_of_right_inverse`) /
is surjective (`quotient_ker_equiv_of_surjective`).
-/
def ker_lift (f : R →+* S) : R ⧸ f.ker →+* S :=
ideal.quotient.lift _ f $ λ r, f.mem_ker.mp
@[simp]
lemma ker_lift_mk (f : R →+* S) (r : R) : ker_lift f (ideal.quotient.mk f.ker r) = f r :=
ideal.quotient.lift_mk _ _ _
/-- The induced map from the quotient by the kernel is injective. -/
lemma ker_lift_injective (f : R →+* S) : function.injective (ker_lift f) :=
assume a b, quotient.induction_on₂' a b $
assume a b (h : f a = f b), ideal.quotient.eq.2 $
show a - b ∈ ker f, by rw [mem_ker, map_sub, h, sub_self]
variable {f}
/-- The **first isomorphism theorem** for commutative rings, computable version. -/
def quotient_ker_equiv_of_right_inverse
{g : S → R} (hf : function.right_inverse g f) :
R ⧸ f.ker ≃+* S :=
{ to_fun := ker_lift f,
inv_fun := (ideal.quotient.mk f.ker) ∘ g,
left_inv := begin
rintro ⟨x⟩,
apply ker_lift_injective,
simp [hf (f x)],
end,
right_inv := hf,
..ker_lift f}
@[simp]
lemma quotient_ker_equiv_of_right_inverse.apply {g : S → R} (hf : function.right_inverse g f)
(x : R ⧸ f.ker) : quotient_ker_equiv_of_right_inverse hf x = ker_lift f x := rfl
@[simp]
lemma quotient_ker_equiv_of_right_inverse.symm.apply {g : S → R} (hf : function.right_inverse g f)
(x : S) : (quotient_ker_equiv_of_right_inverse hf).symm x = ideal.quotient.mk f.ker (g x) := rfl
/-- The **first isomorphism theorem** for commutative rings. -/
noncomputable def quotient_ker_equiv_of_surjective (hf : function.surjective f) :
R ⧸ f.ker ≃+* S :=
quotient_ker_equiv_of_right_inverse (classical.some_spec hf.has_right_inverse)
end comm_ring
/-- The kernel of a homomorphism to a domain is a prime ideal. -/
lemma ker_is_prime {F : Type*} [ring R] [ring S] [is_domain S] [ring_hom_class F R S]
(f : F) : (ker f).is_prime :=
⟨by { rw [ne.def, ideal.eq_top_iff_one], exact not_one_mem_ker f },
λ x y, by simpa only [mem_ker, map_mul] using @eq_zero_or_eq_zero_of_mul_eq_zero S _ _ _ _ _⟩
/-- The kernel of a homomorphism to a field is a maximal ideal. -/
lemma ker_is_maximal_of_surjective {R K F : Type*} [ring R] [field K] [ring_hom_class F R K]
(f : F) (hf : function.surjective f) :
(ker f).is_maximal :=
begin
refine ideal.is_maximal_iff.mpr
⟨λ h1, @one_ne_zero K _ _ $ map_one f ▸ (mem_ker f).mp h1,
λ J x hJ hxf hxJ, _⟩,
obtain ⟨y, hy⟩ := hf (f x)⁻¹,
have H : 1 = y * x - (y * x - 1) := (sub_sub_cancel _ _).symm,
rw H,
refine J.sub_mem (J.mul_mem_left _ hxJ) (hJ _),
rw mem_ker,
simp only [hy, map_sub, map_one, map_mul,
inv_mul_cancel (mt (mem_ker f).mpr hxf), sub_self],
end
end ring_hom
namespace ideal
variables {R : Type*} {S : Type*} {F : Type*}
section semiring
variables [semiring R] [semiring S] [rc : ring_hom_class F R S]
include rc
lemma map_eq_bot_iff_le_ker {I : ideal R} (f : F) : I.map f = ⊥ ↔ I ≤ (ring_hom.ker f) :=
by rw [ring_hom.ker, eq_bot_iff, map_le_iff_le_comap]
lemma ker_le_comap {K : ideal S} (f : F) : ring_hom.ker f ≤ comap f K :=
λ x hx, mem_comap.2 (((ring_hom.mem_ker f).1 hx).symm ▸ K.zero_mem)
end semiring
section ring
variables [ring R] [ring S] [rc : ring_hom_class F R S]
include rc
lemma map_Inf {A : set (ideal R)} {f : F} (hf : function.surjective f) :
(∀ J ∈ A, ring_hom.ker f ≤ J) → map f (Inf A) = Inf (map f '' A) :=
begin
refine λ h, le_antisymm (le_Inf _) _,
{ intros j hj y hy,
cases (mem_map_iff_of_surjective f hf).1 hy with x hx,
cases (set.mem_image _ _ _).mp hj with J hJ,
rw [← hJ.right, ← hx.right],
exact mem_map_of_mem f (Inf_le_of_le hJ.left (le_of_eq rfl) hx.left) },
{ intros y hy,
cases hf y with x hx,
refine hx ▸ (mem_map_of_mem f _),
have : ∀ I ∈ A, y ∈ map f I, by simpa using hy,
rw [submodule.mem_Inf],
intros J hJ,
rcases (mem_map_iff_of_surjective f hf).1 (this J hJ) with ⟨x', hx', rfl⟩,
have : x - x' ∈ J,
{ apply h J hJ,
rw [ring_hom.mem_ker, map_sub, hx, sub_self] },
simpa only [sub_add_cancel] using J.add_mem this hx' }
end
theorem map_is_prime_of_surjective {f : F} (hf : function.surjective f) {I : ideal R}
[H : is_prime I] (hk : ring_hom.ker f ≤ I) : is_prime (map f I) :=
begin
refine ⟨λ h, H.ne_top (eq_top_iff.2 _), λ x y, _⟩,
{ replace h := congr_arg (comap f) h,
rw [comap_map_of_surjective _ hf, comap_top] at h,
exact h ▸ sup_le (le_of_eq rfl) hk },
{ refine λ hxy, (hf x).rec_on (λ a ha, (hf y).rec_on (λ b hb, _)),
rw [← ha, ← hb, ← _root_.map_mul f, mem_map_iff_of_surjective _ hf] at hxy,
rcases hxy with ⟨c, hc, hc'⟩,
rw [← sub_eq_zero, ← map_sub] at hc',
have : a * b ∈ I,
{ convert I.sub_mem hc (hk (hc' : c - a * b ∈ ring_hom.ker f)),
abel },
exact (H.mem_or_mem this).imp (λ h, ha ▸ mem_map_of_mem f h) (λ h, hb ▸ mem_map_of_mem f h) }
end
lemma map_eq_bot_iff_of_injective {I : ideal R} {f : F} (hf : function.injective f) :
I.map f = ⊥ ↔ I = ⊥ :=
by rw [map_eq_bot_iff_le_ker, (ring_hom.injective_iff_ker_eq_bot f).mp hf, le_bot_iff]
omit rc
theorem map_is_prime_of_equiv {F' : Type*} [ring_equiv_class F' R S]
(f : F') {I : ideal R} [is_prime I] :
is_prime (map f I) :=
map_is_prime_of_surjective (equiv_like.surjective f) $ by simp only [ring_hom.ker_equiv, bot_le]
end ring
section comm_ring
variables [comm_ring R] [comm_ring S]
@[simp] lemma mk_ker {I : ideal R} : (quotient.mk I).ker = I :=
by ext; rw [ring_hom.ker, mem_comap, submodule.mem_bot, quotient.eq_zero_iff_mem]
lemma map_mk_eq_bot_of_le {I J : ideal R} (h : I ≤ J) : I.map (J^.quotient.mk) = ⊥ :=
by { rw [map_eq_bot_iff_le_ker, mk_ker], exact h }
lemma ker_quotient_lift {S : Type v} [comm_ring S] {I : ideal R} (f : R →+* S) (H : I ≤ f.ker) :
(ideal.quotient.lift I f H).ker = (f.ker).map I^.quotient.mk :=
begin
ext x,
split,
{ intro hx,
obtain ⟨y, hy⟩ := quotient.mk_surjective x,
rw [ring_hom.mem_ker, ← hy, ideal.quotient.lift_mk, ← ring_hom.mem_ker] at hx,
rw [← hy, mem_map_iff_of_surjective I^.quotient.mk quotient.mk_surjective],
exact ⟨y, hx, rfl⟩ },
{ intro hx,
rw mem_map_iff_of_surjective I^.quotient.mk quotient.mk_surjective at hx,
obtain ⟨y, hy⟩ := hx,
rw [ring_hom.mem_ker, ← hy.right, ideal.quotient.lift_mk, ← (ring_hom.mem_ker f)],
exact hy.left },
end
theorem map_eq_iff_sup_ker_eq_of_surjective {I J : ideal R} (f : R →+* S)
(hf : function.surjective f) : map f I = map f J ↔ I ⊔ f.ker = J ⊔ f.ker :=
by rw [← (comap_injective_of_surjective f hf).eq_iff, comap_map_of_surjective f hf,
comap_map_of_surjective f hf, ring_hom.ker_eq_comap_bot]
theorem map_radical_of_surjective {f : R →+* S} (hf : function.surjective f) {I : ideal R}
(h : ring_hom.ker f ≤ I) : map f (I.radical) = (map f I).radical :=
begin
rw [radical_eq_Inf, radical_eq_Inf],
have : ∀ J ∈ {J : ideal R | I ≤ J ∧ J.is_prime}, f.ker ≤ J := λ J hJ, le_trans h hJ.left,
convert map_Inf hf this,
refine funext (λ j, propext ⟨_, _⟩),
{ rintros ⟨hj, hj'⟩,
haveI : j.is_prime := hj',
exact ⟨comap f j, ⟨⟨map_le_iff_le_comap.1 hj, comap_is_prime f j⟩,
map_comap_of_surjective f hf j⟩⟩ },
{ rintro ⟨J, ⟨hJ, hJ'⟩⟩,
haveI : J.is_prime := hJ.right,
refine ⟨hJ' ▸ map_mono hJ.left, hJ' ▸ map_is_prime_of_surjective hf (le_trans h hJ.left)⟩ },
end
@[simp] lemma bot_quotient_is_maximal_iff (I : ideal R) :
(⊥ : ideal (R ⧸ I)).is_maximal ↔ I.is_maximal :=
⟨λ hI, (@mk_ker _ _ I) ▸
@comap_is_maximal_of_surjective _ _ _ _ _ _ (quotient.mk I) quotient.mk_surjective ⊥ hI,
λ hI, @bot_is_maximal _ (@field.to_division_ring _ (@quotient.field _ _ I hI)) ⟩
/-- See also `ideal.mem_quotient_iff_mem` in case `I ≤ J`. -/
@[simp]
lemma mem_quotient_iff_mem_sup {I J : ideal R} {x : R} :
quotient.mk I x ∈ J.map (quotient.mk I) ↔ x ∈ J ⊔ I :=
by rw [← mem_comap, comap_map_of_surjective (quotient.mk I) quotient.mk_surjective,
← ring_hom.ker_eq_comap_bot, mk_ker]
/-- See also `ideal.mem_quotient_iff_mem_sup` if the assumption `I ≤ J` is not available. -/
lemma mem_quotient_iff_mem {I J : ideal R} (hIJ : I ≤ J) {x : R} :
quotient.mk I x ∈ J.map (quotient.mk I) ↔ x ∈ J :=
by rw [mem_quotient_iff_mem_sup, sup_eq_left.mpr hIJ]
section quotient_algebra
variables (R₁ R₂ : Type*) {A B : Type*}
variables [comm_semiring R₁] [comm_semiring R₂] [comm_ring A] [comm_ring B]
variables [algebra R₁ A] [algebra R₂ A] [algebra R₁ B]
/-- The `R₁`-algebra structure on `A/I` for an `R₁`-algebra `A` -/
instance quotient.algebra {I : ideal A} : algebra R₁ (A ⧸ I) :=
{ to_fun := λ x, ideal.quotient.mk I (algebra_map R₁ A x),
smul := (•),
smul_def' := λ r x, quotient.induction_on' x $ λ x,
((quotient.mk I).congr_arg $ algebra.smul_def _ _).trans (ring_hom.map_mul _ _ _),
commutes' := λ _ _, mul_comm _ _,
.. ring_hom.comp (ideal.quotient.mk I) (algebra_map R₁ A) }
-- Lean can struggle to find this instance later if we don't provide this shortcut
instance quotient.is_scalar_tower [has_smul R₁ R₂] [is_scalar_tower R₁ R₂ A] (I : ideal A) :
is_scalar_tower R₁ R₂ (A ⧸ I) :=
by apply_instance
/-- The canonical morphism `A →ₐ[R₁] A ⧸ I` as morphism of `R₁`-algebras, for `I` an ideal of
`A`, where `A` is an `R₁`-algebra. -/
def quotient.mkₐ (I : ideal A) : A →ₐ[R₁] A ⧸ I :=
⟨λ a, submodule.quotient.mk a, rfl, λ _ _, rfl, rfl, λ _ _, rfl, λ _, rfl⟩
lemma quotient.alg_hom_ext {I : ideal A} {S} [semiring S] [algebra R₁ S] ⦃f g : A ⧸ I →ₐ[R₁] S⦄
(h : f.comp (quotient.mkₐ R₁ I) = g.comp (quotient.mkₐ R₁ I)) : f = g :=
alg_hom.ext $ λ x, quotient.induction_on' x $ alg_hom.congr_fun h
lemma quotient.alg_map_eq (I : ideal A) :
algebra_map R₁ (A ⧸ I) = (algebra_map A (A ⧸ I)).comp (algebra_map R₁ A) :=
rfl
lemma quotient.mkₐ_to_ring_hom (I : ideal A) :
(quotient.mkₐ R₁ I).to_ring_hom = ideal.quotient.mk I := rfl
@[simp] lemma quotient.mkₐ_eq_mk (I : ideal A) :
⇑(quotient.mkₐ R₁ I) = ideal.quotient.mk I := rfl
@[simp] lemma quotient.algebra_map_eq (I : ideal R) :
algebra_map R (R ⧸ I) = I^.quotient.mk :=
rfl
@[simp] lemma quotient.mk_comp_algebra_map (I : ideal A) :
(quotient.mk I).comp (algebra_map R₁ A) = algebra_map R₁ (A ⧸ I) :=
rfl
@[simp] lemma quotient.mk_algebra_map (I : ideal A) (x : R₁) :
quotient.mk I (algebra_map R₁ A x) = algebra_map R₁ (A ⧸ I) x :=
rfl
/-- The canonical morphism `A →ₐ[R₁] I.quotient` is surjective. -/
lemma quotient.mkₐ_surjective (I : ideal A) : function.surjective (quotient.mkₐ R₁ I) :=
surjective_quot_mk _
/-- The kernel of `A →ₐ[R₁] I.quotient` is `I`. -/
@[simp]
lemma quotient.mkₐ_ker (I : ideal A) : (quotient.mkₐ R₁ I : A →+* A ⧸ I).ker = I :=
ideal.mk_ker
variables {R₁}
/-- `ideal.quotient.lift` as an `alg_hom`. -/
def quotient.liftₐ (I : ideal A) (f : A →ₐ[R₁] B) (hI : ∀ (a : A), a ∈ I → f a = 0) :
A ⧸ I →ₐ[R₁] B :=
{ commutes' := λ r, begin
-- this is is_scalar_tower.algebra_map_apply R₁ A (A ⧸ I) but the file `algebra.algebra.tower`
-- imports this file.
have : algebra_map R₁ (A ⧸ I) r = algebra_map A (A ⧸ I) (algebra_map R₁ A r),
{ simp_rw [algebra.algebra_map_eq_smul_one, smul_assoc, one_smul] },
rw [this, ideal.quotient.algebra_map_eq,
ring_hom.to_fun_eq_coe, ideal.quotient.lift_mk, alg_hom.coe_to_ring_hom,
algebra.algebra_map_eq_smul_one, algebra.algebra_map_eq_smul_one, map_smul, map_one],
end
..(ideal.quotient.lift I (f : A →+* B) hI) }
@[simp]
lemma quotient.liftₐ_apply (I : ideal A) (f : A →ₐ[R₁] B) (hI : ∀ (a : A), a ∈ I → f a = 0) (x) :
ideal.quotient.liftₐ I f hI x = ideal.quotient.lift I (f : A →+* B) hI x :=
rfl
lemma quotient.liftₐ_comp (I : ideal A) (f : A →ₐ[R₁] B) (hI : ∀ (a : A), a ∈ I → f a = 0) :
(ideal.quotient.liftₐ I f hI).comp (ideal.quotient.mkₐ R₁ I) = f :=
alg_hom.ext (λ x, (ideal.quotient.lift_mk I (f : A →+* B) hI : _))
lemma ker_lift.map_smul (f : A →ₐ[R₁] B) (r : R₁) (x : A ⧸ f.to_ring_hom.ker) :
f.to_ring_hom.ker_lift (r • x) = r • f.to_ring_hom.ker_lift x :=
begin
obtain ⟨a, rfl⟩ := quotient.mkₐ_surjective R₁ _ x,
rw [← alg_hom.map_smul, quotient.mkₐ_eq_mk, ring_hom.ker_lift_mk],
exact f.map_smul _ _
end
/-- The induced algebras morphism from the quotient by the kernel to the codomain.
This is an isomorphism if `f` has a right inverse (`quotient_ker_alg_equiv_of_right_inverse`) /
is surjective (`quotient_ker_alg_equiv_of_surjective`).
-/
def ker_lift_alg (f : A →ₐ[R₁] B) : (A ⧸ f.to_ring_hom.ker) →ₐ[R₁] B :=
alg_hom.mk' f.to_ring_hom.ker_lift (λ _ _, ker_lift.map_smul f _ _)
@[simp]
lemma ker_lift_alg_mk (f : A →ₐ[R₁] B) (a : A) :
ker_lift_alg f (quotient.mk f.to_ring_hom.ker a) = f a := rfl
@[simp]
lemma ker_lift_alg_to_ring_hom (f : A →ₐ[R₁] B) :
(ker_lift_alg f).to_ring_hom = ring_hom.ker_lift f := rfl
/-- The induced algebra morphism from the quotient by the kernel is injective. -/
lemma ker_lift_alg_injective (f : A →ₐ[R₁] B) : function.injective (ker_lift_alg f) :=
ring_hom.ker_lift_injective f
/-- The **first isomorphism** theorem for algebras, computable version. -/
def quotient_ker_alg_equiv_of_right_inverse
{f : A →ₐ[R₁] B} {g : B → A} (hf : function.right_inverse g f) :
(A ⧸ f.to_ring_hom.ker) ≃ₐ[R₁] B :=
{ ..ring_hom.quotient_ker_equiv_of_right_inverse (λ x, show f.to_ring_hom (g x) = x, from hf x),
..ker_lift_alg f}
@[simp]
lemma quotient_ker_alg_equiv_of_right_inverse.apply {f : A →ₐ[R₁] B} {g : B → A}
(hf : function.right_inverse g f) (x : A ⧸ f.to_ring_hom.ker) :
quotient_ker_alg_equiv_of_right_inverse hf x = ker_lift_alg f x := rfl
@[simp]
lemma quotient_ker_alg_equiv_of_right_inverse_symm.apply {f : A →ₐ[R₁] B} {g : B → A}
(hf : function.right_inverse g f) (x : B) :
(quotient_ker_alg_equiv_of_right_inverse hf).symm x = quotient.mkₐ R₁ f.to_ring_hom.ker (g x) :=
rfl
/-- The **first isomorphism theorem** for algebras. -/
noncomputable def quotient_ker_alg_equiv_of_surjective
{f : A →ₐ[R₁] B} (hf : function.surjective f) : (A ⧸ f.to_ring_hom.ker) ≃ₐ[R₁] B :=
quotient_ker_alg_equiv_of_right_inverse (classical.some_spec hf.has_right_inverse)
/-- The ring hom `R/I →+* S/J` induced by a ring hom `f : R →+* S` with `I ≤ f⁻¹(J)` -/
def quotient_map {I : ideal R} (J : ideal S) (f : R →+* S) (hIJ : I ≤ J.comap f) :
R ⧸ I →+* S ⧸ J :=
(quotient.lift I ((quotient.mk J).comp f) (λ _ ha,
by simpa [function.comp_app, ring_hom.coe_comp, quotient.eq_zero_iff_mem] using hIJ ha))
@[simp]
lemma quotient_map_mk {J : ideal R} {I : ideal S} {f : R →+* S} {H : J ≤ I.comap f}
{x : R} : quotient_map I f H (quotient.mk J x) = quotient.mk I (f x) :=
quotient.lift_mk J _ _
@[simp]
lemma quotient_map_algebra_map {J : ideal A} {I : ideal S} {f : A →+* S} {H : J ≤ I.comap f}
{x : R₁} :
quotient_map I f H (algebra_map R₁ (A ⧸ J) x) = quotient.mk I (f (algebra_map _ _ x)) :=
quotient.lift_mk J _ _
lemma quotient_map_comp_mk {J : ideal R} {I : ideal S} {f : R →+* S} (H : J ≤ I.comap f) :
(quotient_map I f H).comp (quotient.mk J) = (quotient.mk I).comp f :=
ring_hom.ext (λ x, by simp only [function.comp_app, ring_hom.coe_comp, ideal.quotient_map_mk])
/-- The ring equiv `R/I ≃+* S/J` induced by a ring equiv `f : R ≃+** S`, where `J = f(I)`. -/
@[simps]
def quotient_equiv (I : ideal R) (J : ideal S) (f : R ≃+* S) (hIJ : J = I.map (f : R →+* S)) :
R ⧸ I ≃+* S ⧸ J :=
{ inv_fun := quotient_map I ↑f.symm (by {rw hIJ, exact le_of_eq (map_comap_of_equiv I f)}),
left_inv := by {rintro ⟨r⟩, simp },
right_inv := by {rintro ⟨s⟩, simp },
..quotient_map J ↑f (by {rw hIJ, exact @le_comap_map _ S _ _ _ _ _ _}) }
@[simp]
lemma quotient_equiv_mk (I : ideal R) (J : ideal S) (f : R ≃+* S) (hIJ : J = I.map (f : R →+* S))
(x : R) : quotient_equiv I J f hIJ (ideal.quotient.mk I x) = ideal.quotient.mk J (f x) := rfl
@[simp]
lemma quotient_equiv_symm_mk (I : ideal R) (J : ideal S) (f : R ≃+* S)
(hIJ : J = I.map (f : R →+* S)) (x : S) :
(quotient_equiv I J f hIJ).symm (ideal.quotient.mk J x) = ideal.quotient.mk I (f.symm x) := rfl
/-- `H` and `h` are kept as separate hypothesis since H is used in constructing the quotient map. -/
lemma quotient_map_injective' {J : ideal R} {I : ideal S} {f : R →+* S} {H : J ≤ I.comap f}
(h : I.comap f ≤ J) : function.injective (quotient_map I f H) :=
begin
refine (injective_iff_map_eq_zero (quotient_map I f H)).2 (λ a ha, _),
obtain ⟨r, rfl⟩ := quotient.mk_surjective a,
rw [quotient_map_mk, quotient.eq_zero_iff_mem] at ha,
exact (quotient.eq_zero_iff_mem).mpr (h ha),
end
/-- If we take `J = I.comap f` then `quotient_map` is injective automatically. -/
lemma quotient_map_injective {I : ideal S} {f : R →+* S} :
function.injective (quotient_map I f le_rfl) :=
quotient_map_injective' le_rfl
lemma quotient_map_surjective {J : ideal R} {I : ideal S} {f : R →+* S} {H : J ≤ I.comap f}
(hf : function.surjective f) : function.surjective (quotient_map I f H) :=
λ x, let ⟨x, hx⟩ := quotient.mk_surjective x in
let ⟨y, hy⟩ := hf x in ⟨(quotient.mk J) y, by simp [hx, hy]⟩
/-- Commutativity of a square is preserved when taking quotients by an ideal. -/
lemma comp_quotient_map_eq_of_comp_eq {R' S' : Type*} [comm_ring R'] [comm_ring S']
{f : R →+* S} {f' : R' →+* S'} {g : R →+* R'} {g' : S →+* S'} (hfg : f'.comp g = g'.comp f)
(I : ideal S') : (quotient_map I g' le_rfl).comp (quotient_map (I.comap g') f le_rfl) =
(quotient_map I f' le_rfl).comp (quotient_map (I.comap f') g
(le_of_eq (trans (comap_comap f g') (hfg ▸ (comap_comap g f'))))) :=
begin
refine ring_hom.ext (λ a, _),
obtain ⟨r, rfl⟩ := quotient.mk_surjective a,
simp only [ring_hom.comp_apply, quotient_map_mk],
exact congr_arg (quotient.mk I) (trans (g'.comp_apply f r).symm (hfg ▸ (f'.comp_apply g r))),
end
/-- The algebra hom `A/I →+* B/J` induced by an algebra hom `f : A →ₐ[R₁] B` with `I ≤ f⁻¹(J)`. -/
def quotient_mapₐ {I : ideal A} (J : ideal B) (f : A →ₐ[R₁] B) (hIJ : I ≤ J.comap f) :
A ⧸ I →ₐ[R₁] B ⧸ J :=
{ commutes' := λ r, by simp,
..quotient_map J (f : A →+* B) hIJ }
@[simp]
lemma quotient_map_mkₐ {I : ideal A} (J : ideal B) (f : A →ₐ[R₁] B) (H : I ≤ J.comap f)
{x : A} : quotient_mapₐ J f H (quotient.mk I x) = quotient.mkₐ R₁ J (f x) := rfl
lemma quotient_map_comp_mkₐ {I : ideal A} (J : ideal B) (f : A →ₐ[R₁] B) (H : I ≤ J.comap f) :
(quotient_mapₐ J f H).comp (quotient.mkₐ R₁ I) = (quotient.mkₐ R₁ J).comp f :=
alg_hom.ext (λ x, by simp only [quotient_map_mkₐ, quotient.mkₐ_eq_mk, alg_hom.comp_apply])
/-- The algebra equiv `A/I ≃ₐ[R] B/J` induced by an algebra equiv `f : A ≃ₐ[R] B`,
where`J = f(I)`. -/
def quotient_equiv_alg (I : ideal A) (J : ideal B) (f : A ≃ₐ[R₁] B)
(hIJ : J = I.map (f : A →+* B)) :
(A ⧸ I) ≃ₐ[R₁] B ⧸ J :=
{ commutes' := λ r, by simp,
..quotient_equiv I J (f : A ≃+* B) hIJ }
@[priority 100]
instance quotient_algebra {I : ideal A} [algebra R A] :
algebra (R ⧸ I.comap (algebra_map R A)) (A ⧸ I) :=
(quotient_map I (algebra_map R A) (le_of_eq rfl)).to_algebra
lemma algebra_map_quotient_injective {I : ideal A} [algebra R A]:
function.injective (algebra_map (R ⧸ I.comap (algebra_map R A)) (A ⧸ I)) :=
begin
rintros ⟨a⟩ ⟨b⟩ hab,
replace hab := quotient.eq.mp hab,
rw ← ring_hom.map_sub at hab,
exact quotient.eq.mpr hab
end
end quotient_algebra
end comm_ring
end ideal
namespace submodule
variables {R : Type u} {M : Type v}
variables [comm_semiring R] [add_comm_monoid M] [module R M]
-- TODO: show `[algebra R A] : algebra (ideal R) A` too
instance module_submodule : module (ideal R) (submodule R M) :=
{ smul_add := smul_sup,
add_smul := sup_smul,
mul_smul := submodule.smul_assoc,
one_smul := by simp,
zero_smul := bot_smul,
smul_zero := smul_bot }
end submodule
namespace ring_hom
variables {A B C : Type*} [ring A] [ring B] [ring C]
variables (f : A →+* B) (f_inv : B → A)
/-- Auxiliary definition used to define `lift_of_right_inverse` -/
def lift_of_right_inverse_aux
(hf : function.right_inverse f_inv f) (g : A →+* C) (hg : f.ker ≤ g.ker) :
B →+* C :=
{ to_fun := λ b, g (f_inv b),
map_one' :=
begin
rw [← g.map_one, ← sub_eq_zero, ← g.map_sub, ← g.mem_ker],
apply hg,
rw [f.mem_ker, f.map_sub, sub_eq_zero, f.map_one],
exact hf 1
end,
map_mul' :=
begin
intros x y,
rw [← g.map_mul, ← sub_eq_zero, ← g.map_sub, ← g.mem_ker],
apply hg,
rw [f.mem_ker, f.map_sub, sub_eq_zero, f.map_mul],
simp only [hf _],
end,
.. add_monoid_hom.lift_of_right_inverse f.to_add_monoid_hom f_inv hf ⟨g.to_add_monoid_hom, hg⟩ }
@[simp] lemma lift_of_right_inverse_aux_comp_apply
(hf : function.right_inverse f_inv f) (g : A →+* C) (hg : f.ker ≤ g.ker) (a : A) :
(f.lift_of_right_inverse_aux f_inv hf g hg) (f a) = g a :=
f.to_add_monoid_hom.lift_of_right_inverse_comp_apply f_inv hf ⟨g.to_add_monoid_hom, hg⟩ a
/-- `lift_of_right_inverse f hf g hg` is the unique ring homomorphism `φ`
* such that `φ.comp f = g` (`ring_hom.lift_of_right_inverse_comp`),
* where `f : A →+* B` is has a right_inverse `f_inv` (`hf`),
* and `g : B →+* C` satisfies `hg : f.ker ≤ g.ker`.
See `ring_hom.eq_lift_of_right_inverse` for the uniqueness lemma.
```
A .
| \
f | \ g
| \
v \⌟
B ----> C
∃!φ
```
-/
def lift_of_right_inverse
(hf : function.right_inverse f_inv f) : {g : A →+* C // f.ker ≤ g.ker} ≃ (B →+* C) :=
{ to_fun := λ g, f.lift_of_right_inverse_aux f_inv hf g.1 g.2,
inv_fun := λ φ, ⟨φ.comp f, λ x hx, (mem_ker _).mpr $ by simp [(mem_ker _).mp hx]⟩,
left_inv := λ g, by
{ ext,
simp only [comp_apply, lift_of_right_inverse_aux_comp_apply, subtype.coe_mk,
subtype.val_eq_coe], },
right_inv := λ φ, by
{ ext b,
simp [lift_of_right_inverse_aux, hf b], } }
/-- A non-computable version of `ring_hom.lift_of_right_inverse` for when no computable right
inverse is available, that uses `function.surj_inv`. -/
@[simp]
noncomputable abbreviation lift_of_surjective
(hf : function.surjective f) : {g : A →+* C // f.ker ≤ g.ker} ≃ (B →+* C) :=
f.lift_of_right_inverse (function.surj_inv hf) (function.right_inverse_surj_inv hf)
lemma lift_of_right_inverse_comp_apply
(hf : function.right_inverse f_inv f) (g : {g : A →+* C // f.ker ≤ g.ker}) (x : A) :
(f.lift_of_right_inverse f_inv hf g) (f x) = g x :=
f.lift_of_right_inverse_aux_comp_apply f_inv hf g.1 g.2 x
lemma lift_of_right_inverse_comp (hf : function.right_inverse f_inv f)
(g : {g : A →+* C // f.ker ≤ g.ker}) :
(f.lift_of_right_inverse f_inv hf g).comp f = g :=
ring_hom.ext $ f.lift_of_right_inverse_comp_apply f_inv hf g
lemma eq_lift_of_right_inverse (hf : function.right_inverse f_inv f) (g : A →+* C)
(hg : f.ker ≤ g.ker) (h : B →+* C) (hh : h.comp f = g) :
h = (f.lift_of_right_inverse f_inv hf ⟨g, hg⟩) :=
begin
simp_rw ←hh,
exact ((f.lift_of_right_inverse f_inv hf).apply_symm_apply _).symm,
end
end ring_hom
namespace double_quot
open ideal
variable {R : Type u}
section
variables [comm_ring R] (I J : ideal R)
/-- The obvious ring hom `R/I → R/(I ⊔ J)` -/
def quot_left_to_quot_sup : R ⧸ I →+* R ⧸ (I ⊔ J) :=
ideal.quotient.factor I (I ⊔ J) le_sup_left
/-- The kernel of `quot_left_to_quot_sup` -/
lemma ker_quot_left_to_quot_sup :
(quot_left_to_quot_sup I J).ker = J.map (ideal.quotient.mk I) :=
by simp only [mk_ker, sup_idem, sup_comm, quot_left_to_quot_sup, quotient.factor, ker_quotient_lift,
map_eq_iff_sup_ker_eq_of_surjective I^.quotient.mk quotient.mk_surjective, ← sup_assoc]
/-- The ring homomorphism `(R/I)/J' -> R/(I ⊔ J)` induced by `quot_left_to_quot_sup` where `J'`
is the image of `J` in `R/I`-/
def quot_quot_to_quot_sup : (R ⧸ I) ⧸ J.map (ideal.quotient.mk I) →+* R ⧸ I ⊔ J :=
by exact ideal.quotient.lift (J.map (ideal.quotient.mk I)) (quot_left_to_quot_sup I J)
(ker_quot_left_to_quot_sup I J).symm.le
/-- The composite of the maps `R → (R/I)` and `(R/I) → (R/I)/J'` -/
def quot_quot_mk : R →+* ((R ⧸ I) ⧸ J.map I^.quotient.mk) :=
by exact ((J.map I^.quotient.mk)^.quotient.mk).comp I^.quotient.mk
/-- The kernel of `quot_quot_mk` -/
lemma ker_quot_quot_mk : (quot_quot_mk I J).ker = I ⊔ J :=
by rw [ring_hom.ker_eq_comap_bot, quot_quot_mk, ← comap_comap, ← ring_hom.ker, mk_ker,
comap_map_of_surjective (ideal.quotient.mk I) (quotient.mk_surjective), ← ring_hom.ker, mk_ker,
sup_comm]
/-- The ring homomorphism `R/(I ⊔ J) → (R/I)/J' `induced by `quot_quot_mk` -/
def lift_sup_quot_quot_mk (I J : ideal R) :
R ⧸ (I ⊔ J) →+* (R ⧸ I) ⧸ J.map (ideal.quotient.mk I) :=
ideal.quotient.lift (I ⊔ J) (quot_quot_mk I J) (ker_quot_quot_mk I J).symm.le
/-- `quot_quot_to_quot_add` and `lift_sup_double_qot_mk` are inverse isomorphisms -/
def quot_quot_equiv_quot_sup : (R ⧸ I) ⧸ J.map (ideal.quotient.mk I) ≃+* R ⧸ I ⊔ J :=
ring_equiv.of_hom_inv (quot_quot_to_quot_sup I J) (lift_sup_quot_quot_mk I J)
(by { ext z, refl }) (by { ext z, refl })
@[simp]
lemma quot_quot_equiv_quot_sup_quot_quot_mk (x : R) :
quot_quot_equiv_quot_sup I J (quot_quot_mk I J x) = ideal.quotient.mk (I ⊔ J) x :=
rfl
@[simp]
lemma quot_quot_equiv_quot_sup_symm_quot_quot_mk (x : R) :
(quot_quot_equiv_quot_sup I J).symm (ideal.quotient.mk (I ⊔ J) x) = quot_quot_mk I J x :=
rfl
/-- The obvious isomorphism `(R/I)/J' → (R/J)/I' ` -/
def quot_quot_equiv_comm :
(R ⧸ I) ⧸ J.map I^.quotient.mk ≃+* (R ⧸ J) ⧸ I.map J^.quotient.mk :=
((quot_quot_equiv_quot_sup I J).trans (quot_equiv_of_eq sup_comm)).trans
(quot_quot_equiv_quot_sup J I).symm
@[simp]
lemma quot_quot_equiv_comm_quot_quot_mk (x : R) :
quot_quot_equiv_comm I J (quot_quot_mk I J x) = quot_quot_mk J I x :=
rfl
@[simp]
lemma quot_quot_equiv_comm_comp_quot_quot_mk :
ring_hom.comp ↑(quot_quot_equiv_comm I J) (quot_quot_mk I J) = quot_quot_mk J I :=
ring_hom.ext $ quot_quot_equiv_comm_quot_quot_mk I J
@[simp]
lemma quot_quot_equiv_comm_symm :
(quot_quot_equiv_comm I J).symm = quot_quot_equiv_comm J I :=
rfl
end
section algebra
@[simp]
lemma quot_quot_equiv_comm_mk_mk [comm_ring R] (I J : ideal R) (x : R) :
quot_quot_equiv_comm I J (ideal.quotient.mk _ (ideal.quotient.mk _ x)) =
algebra_map R _ x := rfl
variables [comm_semiring R] {A : Type v} [comm_ring A] [algebra R A] (I J : ideal A)
@[simp]
lemma quot_quot_equiv_quot_sup_quot_quot_algebra_map (x : R) :
double_quot.quot_quot_equiv_quot_sup I J (algebra_map R _ x) = algebra_map _ _ x :=
rfl
@[simp]
lemma quot_quot_equiv_comm_algebra_map (x : R) :
quot_quot_equiv_comm I J (algebra_map R _ x) = algebra_map _ _ x := rfl
end algebra
end double_quot
|
2aa3b2e1ccc14e223f482768efea629c25c55dbd | cf39355caa609c0f33405126beee2739aa3cb77e | /library/init/data/list/lemmas.lean | db03c74f1e95b613320b63360fff38b3e9d97ff4 | [
"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 | 10,534 | lean | /-
Copyright (c) 2014 Parikshit Khanna. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Parikshit Khanna, Jeremy Avigad, Leonardo de Moura, Floris van Doorn
-/
prelude
import init.data.list.basic init.function init.meta init.data.nat.lemmas
import init.meta.interactive init.meta.smt.rsimp
universes u v w w₁ w₂
variables {α : Type u} {β : Type v} {γ : Type w}
namespace list
open nat
/-! append -/
@[simp] lemma nil_append (s : list α) : [] ++ s = s :=
rfl
@[simp] lemma cons_append (x : α) (s t : list α) : (x::s) ++ t = x::(s ++ t) :=
rfl
@[simp] lemma append_nil (t : list α) : t ++ [] = t :=
by induction t; simp [*]
@[simp] lemma append_assoc (s t u : list α) : s ++ t ++ u = s ++ (t ++ u) :=
by induction s; simp [*]
/-! length -/
lemma length_cons (a : α) (l : list α) : length (a :: l) = length l + 1 :=
rfl
@[simp] lemma length_append (s t : list α) : length (s ++ t) = length s + length t :=
begin
induction s,
{ show length t = 0 + length t, by rw nat.zero_add },
{ simp [*, nat.add_comm, nat.add_left_comm] },
end
@[simp] lemma length_repeat (a : α) (n : ℕ) : length (repeat a n) = n :=
by induction n; simp [*]; refl
@[simp] lemma length_tail (l : list α) : length (tail l) = length l - 1 :=
by cases l; refl
-- TODO(Leo): cleanup proof after arith dec proc
@[simp] lemma length_drop : ∀ (i : ℕ) (l : list α), length (drop i l) = length l - i
| 0 l := rfl
| (succ i) [] := eq.symm (nat.zero_sub (succ i))
| (succ i) (x::l) := calc
length (drop (succ i) (x::l))
= length l - i : length_drop i l
... = succ (length l) - succ i : (nat.succ_sub_succ_eq_sub (length l) i).symm
/-! map -/
lemma map_cons (f : α → β) (a l) : map f (a::l) = f a :: map f l :=
rfl
@[simp] lemma map_append (f : α → β) : ∀ l₁ l₂, map f (l₁ ++ l₂) = (map f l₁) ++ (map f l₂) :=
by intro l₁; induction l₁; intros; simp [*]
lemma map_singleton (f : α → β) (a : α) : map f [a] = [f a] :=
rfl
@[simp] lemma map_id (l : list α) : map id l = l :=
by induction l; simp [*]
@[simp] lemma map_map (g : β → γ) (f : α → β) (l : list α) : map g (map f l) = map (g ∘ f) l :=
by induction l; simp [*]
@[simp] lemma length_map (f : α → β) (l : list α) : length (map f l) = length l :=
by induction l; simp [*]
/-! bind -/
@[simp] lemma nil_bind (f : α → list β) : list.bind [] f = [] :=
by simp [join, list.bind]
@[simp] lemma cons_bind (x xs) (f : α → list β) : list.bind (x :: xs) f = f x ++ list.bind xs f :=
by simp [join, list.bind]
@[simp] lemma append_bind (xs ys) (f : α → list β) :
list.bind (xs ++ ys) f = list.bind xs f ++ list.bind ys f :=
by induction xs; [refl, simp [*, cons_bind]]
/-! mem -/
lemma mem_nil_iff (a : α) : a ∈ ([] : list α) ↔ false :=
iff.rfl
@[simp] lemma not_mem_nil (a : α) : a ∉ ([] : list α) :=
not_false
lemma mem_cons_self (a : α) (l : list α) : a ∈ a :: l :=
or.inl rfl
@[simp] lemma mem_cons_iff (a y : α) (l : list α) : a ∈ y :: l ↔ (a = y ∨ a ∈ l) :=
iff.rfl
@[rsimp] lemma mem_cons_eq (a y : α) (l : list α) : (a ∈ y :: l) = (a = y ∨ a ∈ l) :=
rfl
lemma mem_cons_of_mem (y : α) {a : α} {l : list α} : a ∈ l → a ∈ y :: l :=
assume H, or.inr H
lemma eq_or_mem_of_mem_cons {a y : α} {l : list α} : a ∈ y::l → a = y ∨ a ∈ l :=
assume h, h
@[simp] lemma mem_append {a : α} {s t : list α} : a ∈ s ++ t ↔ a ∈ s ∨ a ∈ t :=
by induction s; simp [*, or_assoc]
@[rsimp] lemma mem_append_eq (a : α) (s t : list α) : (a ∈ s ++ t) = (a ∈ s ∨ a ∈ t) :=
propext mem_append
lemma mem_append_left {a : α} {l₁ : list α} (l₂ : list α) (h : a ∈ l₁) : a ∈ l₁ ++ l₂ :=
mem_append.2 (or.inl h)
lemma mem_append_right {a : α} (l₁ : list α) {l₂ : list α} (h : a ∈ l₂) : a ∈ l₁ ++ l₂ :=
mem_append.2 (or.inr h)
lemma not_bex_nil (p : α → Prop) : ¬ (∃ x ∈ @nil α, p x) :=
λ⟨x, hx, px⟩, hx
lemma ball_nil (p : α → Prop) : ∀ x ∈ @nil α, p x :=
λx, false.elim
lemma bex_cons (p : α → Prop) (a : α) (l : list α) :
(∃ x ∈ (a :: l), p x) ↔ (p a ∨ ∃ x ∈ l, p x) :=
⟨λ⟨x, h, px⟩, by {
simp at h, cases h with h h, {cases h, exact or.inl px}, {exact or.inr ⟨x, h, px⟩}},
λo, o.elim (λpa, ⟨a, mem_cons_self _ _, pa⟩)
(λ⟨x, h, px⟩, ⟨x, mem_cons_of_mem _ h, px⟩)⟩
lemma ball_cons (p : α → Prop) (a : α) (l : list α) :
(∀ x ∈ (a :: l), p x) ↔ (p a ∧ ∀ x ∈ l, p x) :=
⟨λal, ⟨al a (mem_cons_self _ _), λx h, al x (mem_cons_of_mem _ h)⟩,
λ⟨pa, al⟩ x o, o.elim (λe, e.symm ▸ pa) (al x)⟩
/-! list subset -/
protected def subset (l₁ l₂ : list α) := ∀ ⦃a : α⦄, a ∈ l₁ → a ∈ l₂
instance : has_subset (list α) := ⟨list.subset⟩
@[simp] lemma nil_subset (l : list α) : [] ⊆ l :=
λ b i, false.elim (iff.mp (mem_nil_iff b) i)
@[refl, simp] lemma subset.refl (l : list α) : l ⊆ l :=
λ b i, i
@[trans] lemma subset.trans {l₁ l₂ l₃ : list α} (h₁ : l₁ ⊆ l₂) (h₂ : l₂ ⊆ l₃) : l₁ ⊆ l₃ :=
λ b i, h₂ (h₁ i)
@[simp] lemma subset_cons (a : α) (l : list α) : l ⊆ a::l :=
λ b i, or.inr i
lemma subset_of_cons_subset {a : α} {l₁ l₂ : list α} : a::l₁ ⊆ l₂ → l₁ ⊆ l₂ :=
λ s b i, s (mem_cons_of_mem _ i)
lemma cons_subset_cons {l₁ l₂ : list α} (a : α) (s : l₁ ⊆ l₂) : (a::l₁) ⊆ (a::l₂) :=
λ b hin, or.elim (eq_or_mem_of_mem_cons hin)
(λ e : b = a, or.inl e)
(λ i : b ∈ l₁, or.inr (s i))
@[simp] lemma subset_append_left (l₁ l₂ : list α) : l₁ ⊆ l₁++l₂ :=
λ b, mem_append_left _
@[simp] lemma subset_append_right (l₁ l₂ : list α) : l₂ ⊆ l₁++l₂ :=
λ b, mem_append_right _
lemma subset_cons_of_subset (a : α) {l₁ l₂ : list α} : l₁ ⊆ l₂ → l₁ ⊆ (a::l₂) :=
λ (s : l₁ ⊆ l₂) (a : α) (i : a ∈ l₁), or.inr (s i)
theorem eq_nil_of_length_eq_zero {l : list α} : length l = 0 → l = [] :=
by {induction l; intros, refl, contradiction}
theorem ne_nil_of_length_eq_succ {l : list α} : ∀ {n : nat}, length l = succ n → l ≠ [] :=
by induction l; intros; contradiction
@[simp] theorem length_map₂ (f : α → β → γ) (l₁) : ∀ l₂, length (map₂ f l₁ l₂) = min (length l₁) (length l₂) :=
by { induction l₁; intro l₂; cases l₂; simp [*, add_one, min_succ_succ, nat.zero_min, nat.min_zero] }
@[simp] theorem length_take : ∀ (i : ℕ) (l : list α), length (take i l) = min i (length l)
| 0 l := by simp [nat.zero_min]
| (succ n) [] := by simp [nat.min_zero]
| (succ n) (a::l) := by simp [*, nat.min_succ_succ, add_one]
theorem length_take_le (n) (l : list α) : length (take n l) ≤ n :=
by simp [min_le_left]
theorem length_remove_nth : ∀ (l : list α) (i : ℕ), i < length l → length (remove_nth l i) = length l - 1
| [] _ h := rfl
| (x::xs) 0 h := by simp [remove_nth]
| (x::xs) (i+1) h := have i < length xs, from lt_of_succ_lt_succ h,
by dsimp [remove_nth]; rw [length_remove_nth xs i this, nat.sub_add_cancel (lt_of_le_of_lt (nat.zero_le _) this)]; refl
@[simp] lemma partition_eq_filter_filter (p : α → Prop) [decidable_pred p] : ∀ (l : list α), partition p l = (filter p l, filter (not ∘ p) l)
| [] := rfl
| (a::l) := by { by_cases pa : p a; simp [partition, filter, pa, partition_eq_filter_filter l] }
/-! sublists -/
inductive sublist : list α → list α → Prop
| slnil : sublist [] []
| cons (l₁ l₂ a) : sublist l₁ l₂ → sublist l₁ (a::l₂)
| cons2 (l₁ l₂ a) : sublist l₁ l₂ → sublist (a::l₁) (a::l₂)
infix ` <+ `:50 := sublist
lemma length_le_of_sublist : ∀ {l₁ l₂ : list α}, l₁ <+ l₂ → length l₁ ≤ length l₂
| _ _ sublist.slnil := le_refl 0
| _ _ (sublist.cons l₁ l₂ a s) := le_succ_of_le (length_le_of_sublist s)
| _ _ (sublist.cons2 l₁ l₂ a s) := succ_le_succ (length_le_of_sublist s)
/-! filter -/
@[simp] theorem filter_nil (p : α → Prop) [h : decidable_pred p] : filter p [] = [] := rfl
@[simp] theorem filter_cons_of_pos {p : α → Prop} [h : decidable_pred p] {a : α} :
∀ l, p a → filter p (a::l) = a :: filter p l :=
λ l pa, if_pos pa
@[simp] theorem filter_cons_of_neg {p : α → Prop} [h : decidable_pred p] {a : α} :
∀ l, ¬ p a → filter p (a::l) = filter p l :=
λ l pa, if_neg pa
@[simp] theorem filter_append {p : α → Prop} [h : decidable_pred p] :
∀ (l₁ l₂ : list α), filter p (l₁++l₂) = filter p l₁ ++ filter p l₂
| [] l₂ := rfl
| (a::l₁) l₂ := by by_cases pa : p a; simp [pa, filter_append]
@[simp] theorem filter_sublist {p : α → Prop} [h : decidable_pred p] : Π (l : list α), filter p l <+ l
| [] := sublist.slnil
| (a::l) := if pa : p a
then by simp [pa]; apply sublist.cons2; apply filter_sublist l
else by simp [pa]; apply sublist.cons; apply filter_sublist l
/-! map_accumr -/
section map_accumr
variables {φ : Type w₁} {σ : Type w₂}
-- This runs a function over a list returning the intermediate results and a
-- a final result.
def map_accumr (f : α → σ → σ × β) : list α → σ → (σ × list β)
| [] c := (c, [])
| (y::yr) c :=
let r := map_accumr yr c in
let z := f y r.1 in
(z.1, z.2 :: r.2)
@[simp] theorem length_map_accumr
: ∀ (f : α → σ → σ × β) (x : list α) (s : σ),
length (map_accumr f x s).2 = length x
| f (a::x) s := congr_arg succ (length_map_accumr f x s)
| f [] s := rfl
end map_accumr
section map_accumr₂
variables {φ : Type w₁} {σ : Type w₂}
-- This runs a function over two lists returning the intermediate results and a
-- a final result.
def map_accumr₂ (f : α → β → σ → σ × φ)
: list α → list β → σ → σ × list φ
| [] _ c := (c,[])
| _ [] c := (c,[])
| (x::xr) (y::yr) c :=
let r := map_accumr₂ xr yr c in
let q := f x y r.1 in
(q.1, q.2 :: r.2)
@[simp] theorem length_map_accumr₂ : ∀ (f : α → β → σ → σ × φ) x y c,
length (map_accumr₂ f x y c).2 = min (length x) (length y)
| f (a::x) (b::y) c := calc
succ (length (map_accumr₂ f x y c).2)
= succ (min (length x) (length y))
: congr_arg succ (length_map_accumr₂ f x y c)
... = min (succ (length x)) (succ (length y))
: eq.symm (min_succ_succ (length x) (length y))
| f (a::x) [] c := rfl
| f [] (b::y) c := rfl
| f [] [] c := rfl
end map_accumr₂
end list
|
c348bca33ab937bf0f6af285223a97dffb3d074e | 9dd3f3912f7321eb58ee9aa8f21778ad6221f87c | /library/init/meta/tactic.lean | 547ccc017c151e1bdc0d1075bfe5a69bdd599ea0 | [
"Apache-2.0"
] | permissive | bre7k30/lean | de893411bcfa7b3c5572e61b9e1c52951b310aa4 | 5a924699d076dab1bd5af23a8f910b433e598d7a | refs/heads/master | 1,610,900,145,817 | 1,488,006,845,000 | 1,488,006,845,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 38,396 | 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.function init.data.option.basic init.util
import init.category.combinators init.category.monad init.category.alternative init.category.monad_fail
import init.data.nat.div init.meta.exceptional init.meta.format init.meta.environment
import init.meta.pexpr init.data.to_string init.data.string.basic init.meta.interaction_monad
meta constant tactic_state : Type
universes u v
namespace tactic_state
meta constant env : tactic_state → environment
meta constant to_format : tactic_state → format
/- Format expression with respect to the main goal in the tactic state.
If the tactic state does not contain any goals, then format expression
using an empty local context. -/
meta constant format_expr : tactic_state → expr → format
meta constant get_options : tactic_state → options
meta constant set_options : tactic_state → options → tactic_state
end tactic_state
meta instance : has_to_format tactic_state :=
⟨tactic_state.to_format⟩
@[reducible] meta def tactic := interaction_monad tactic_state
@[reducible] meta def tactic_result := interaction_monad.result tactic_state
namespace tactic
export interaction_monad (hiding failed fail)
meta def failed {α : Type} : tactic α := interaction_monad.failed
meta def fail {α : Type u} {β : Type v} [has_to_format β] (msg : β) : tactic α :=
interaction_monad.fail msg
end tactic
namespace tactic_result
export interaction_monad.result
end tactic_result
open tactic
open tactic_result
infixl ` >>=[tactic] `:2 := interaction_monad_bind
infixl ` >>[tactic] `:2 := interaction_monad_seq
meta instance : alternative tactic :=
⟨@interaction_monad_fmap tactic_state, (λ α a s, success a s), (@fapp _ _), @interaction_monad.failed tactic_state, @interaction_monad_orelse tactic_state⟩
meta def {u₁ u₂} tactic.up {α : Type u₂} (t : tactic α) : tactic (ulift.{u₁} α) :=
λ s, match t s with
| success a s' := success (ulift.up a) s'
| exception t ref s := exception t ref s
end
meta def {u₁ u₂} tactic.down {α : Type u₂} (t : tactic (ulift.{u₁} α)) : tactic α :=
λ s, match t s with
| success (ulift.up a) s' := success a s'
| exception t ref s := exception t ref s
end
namespace tactic
variables {α : Type u}
meta def try_core (t : tactic α) : tactic (option α) :=
λ s, result.cases_on (t s)
(λ a, success (some a))
(λ e ref s', success none s)
meta def skip : tactic unit :=
success ()
meta def try (t : tactic α) : tactic unit :=
try_core t >>[tactic] skip
meta def fail_if_success {α : Type u} (t : tactic α) : tactic unit :=
λ s, result.cases_on (t s)
(λ a s, mk_exception "fail_if_success combinator failed, given tactic succeeded" none s)
(λ e ref s', success () s)
open nat
/- (repeat_at_most n t): repeat the given tactic at most n times or until t fails -/
meta def repeat_at_most : nat → tactic unit → tactic unit
| 0 t := skip
| (succ n) t := (do t, repeat_at_most n t) <|> skip
/- (repeat_exactly n t) : execute t n times -/
meta def repeat_exactly : nat → tactic unit → tactic unit
| 0 t := skip
| (succ n) t := do t, repeat_exactly n t
meta def repeat : tactic unit → tactic unit :=
repeat_at_most 100000
meta def returnopt (e : option α) : tactic α :=
λ s, match e with
| (some a) := success a s
| none := mk_exception "failed" none s
end
meta instance opt_to_tac : has_coe (option α) (tactic α) :=
⟨returnopt⟩
/- Decorate t's exceptions with msg -/
meta def decorate_ex (msg : format) (t : tactic α) : tactic α :=
λ s, result.cases_on (t s)
success
(λ opt_thunk,
match opt_thunk with
| some e := exception (some (λ u, msg ++ format.nest 2 (format.line ++ e u)))
| none := exception none
end)
@[inline] meta def write (s' : tactic_state) : tactic unit :=
λ s, success () s'
@[inline] meta def read : tactic tactic_state :=
λ s, success s s
meta def get_options : tactic options :=
do s ← read, return s^.get_options
meta def set_options (o : options) : tactic unit :=
do s ← read, write (s^.set_options o)
meta def save_options {α : Type} (t : tactic α) : tactic α :=
do o ← get_options,
a ← t,
set_options o,
return a
meta def returnex {α : Type} (e : exceptional α) : tactic α :=
λ s, match e with
| exceptional.success a := success a s
| exceptional.exception .α f :=
match get_options s with
| success opt _ := exception (some (λ u, f opt)) none s
| exception _ _ _ := exception (some (λ u, f options.mk)) none s
end
end
meta instance ex_to_tac {α : Type} : has_coe (exceptional α) (tactic α) :=
⟨returnex⟩
end tactic
meta def tactic_format_expr (e : expr) : tactic format :=
do s ← tactic.read, return (tactic_state.format_expr s e)
meta class has_to_tactic_format (α : Type u) :=
(to_tactic_format : α → tactic format)
meta instance : has_to_tactic_format expr :=
⟨tactic_format_expr⟩
meta def tactic.pp {α : Type u} [has_to_tactic_format α] : α → tactic format :=
has_to_tactic_format.to_tactic_format
open tactic format
meta instance {α : Type u} [has_to_tactic_format α] : has_to_tactic_format (list α) :=
⟨fmap to_fmt ∘ monad.mapm pp⟩
meta instance (α : Type u) (β : Type v) [has_to_tactic_format α] [has_to_tactic_format β] :
has_to_tactic_format (α × β) :=
⟨λ ⟨a, b⟩, to_fmt <$> (prod.mk <$> pp a <*> pp b)⟩
meta def option_to_tactic_format {α : Type u} [has_to_tactic_format α] : option α → tactic format
| (some a) := do fa ← pp a, return (to_fmt "(some " ++ fa ++ ")")
| none := return "none"
meta instance {α : Type u} [has_to_tactic_format α] : has_to_tactic_format (option α) :=
⟨option_to_tactic_format⟩
meta instance has_to_format_to_has_to_tactic_format (α : Type) [has_to_format α] : has_to_tactic_format α :=
⟨(λ x, return x) ∘ to_fmt⟩
namespace tactic
open tactic_state
meta def get_env : tactic environment :=
do s ← read,
return $ env s
meta def get_decl (n : name) : tactic declaration :=
do s ← read,
(env s)^.get n
meta def trace {α : Type u} [has_to_tactic_format α] (a : α) : tactic unit :=
do fmt ← pp a,
return $ _root_.trace_fmt fmt (λ u, ())
meta def trace_call_stack : tactic unit :=
take state, _root_.trace_call_stack (success () state)
meta def timetac {α : Type u} (desc : string) (t : tactic α) : tactic α :=
λ s, timeit desc (t s)
meta def trace_state : tactic unit :=
do s ← read,
trace $ to_fmt s
inductive transparency
| all | semireducible | reducible | none
export transparency (reducible semireducible)
/- (eval_expr α α_as_expr e) evaluates 'e' IF 'e' has type 'α'.
'α' must be a closed term.
'α_as_expr' is synthesized by the code generator.
'e' must be a closed expression at runtime. -/
meta constant eval_expr (α : Type u) {α_expr : pexpr} : expr → tactic α
/- Return the partial term/proof constructed so far. Note that the resultant expression
may contain variables that are not declarate in the current main goal. -/
meta constant result : tactic expr
/- Display the partial term/proof constructed so far. This tactic is *not* equivalent to
do { r ← result, s ← read, return (format_expr s r) } because this one will format the result with respect
to the current goal, and trace_result will do it with respect to the initial goal. -/
meta constant format_result : tactic format
/- Return target type of the main goal. Fail if tactic_state does not have any goal left. -/
meta constant target : tactic expr
meta constant intro_core : name → tactic expr
meta constant intron : nat → tactic unit
meta constant rename : name → name → tactic unit
/- Clear the given local constant. The tactic fails if the given expression is not a local constant. -/
meta constant clear : expr → tactic unit
meta constant revert_lst : list expr → tactic nat
/-- Return `e` in weak head normal form with respect to the given transparency setting. -/
meta constant whnf (e : expr) (md := semireducible) : tactic expr
/- (head) eta expand the given expression -/
meta constant eta_expand : expr → tactic expr
/- (head) beta reduction -/
meta constant beta : expr → tactic expr
/- (head) zeta reduction -/
meta constant zeta : expr → tactic expr
/- (head) eta reduction -/
meta constant eta : expr → tactic expr
/-- Succeeds if `t` and `s` can be unified using the given transparency setting. -/
meta constant unify (t s : expr) (md := semireducible) : tactic unit
/- Similar to `unify`, but it treats metavariables as constants. -/
meta constant is_def_eq (t s : expr) (md := semireducible) : tactic unit
/- Infer the type of the given expression.
Remark: transparency does not affect type inference -/
meta constant infer_type : expr → tactic expr
meta constant get_local : name → tactic expr
/- Resolve a name using the current local context, environment, aliases, etc. -/
meta constant resolve_name : name → tactic expr
/- Return the hypothesis in the main goal. Fail if tactic_state does not have any goal left. -/
meta constant local_context : tactic (list expr)
meta constant get_unused_name : name → option nat → tactic name
/-- Helper tactic for creating simple applications where some arguments are inferred using
type inference.
Example, given
```
rel.{l_1 l_2} : Pi (α : Type.{l_1}) (β : α -> Type.{l_2}), (Pi x : α, β x) -> (Pi x : α, β x) -> , Prop
nat : Type
real : Type
vec.{l} : Pi (α : Type l) (n : nat), Type.{l1}
f g : Pi (n : nat), vec real n
```
then
```
mk_app_core semireducible "rel" [f, g]
```
returns the application
```
rel.{1 2} nat (fun n : nat, vec real n) f g
```
The unification constraints due to type inference are solved using the transparency `md`.
-/
meta constant mk_app (fn : name) (args : list expr) (md := semireducible) : tactic expr
/-- Similar to `mk_app`, but allows to specify which arguments are explicit/implicit.
Example, given `(a b : nat)` then
```
mk_mapp "ite" [some (a > b), none, none, some a, some b]
```
returns the application
```
@ite.{1} (a > b) (nat.decidable_gt a b) nat a b
```
-/
meta constant mk_mapp (fn : name) (args : list (option expr)) (md := semireducible) : tactic expr
/-- (mk_congr_arg h₁ h₂) is a more efficient version of (mk_app `congr_arg [h₁, h₂]) -/
meta constant mk_congr_arg : expr → expr → tactic expr
/-- (mk_congr_fun h₁ h₂) is a more efficient version of (mk_app `congr_fun [h₁, h₂]) -/
meta constant mk_congr_fun : expr → expr → tactic expr
/-- (mk_congr h₁ h₂) is a more efficient version of (mk_app `congr [h₁, h₂]) -/
meta constant mk_congr : expr → expr → tactic expr
/-- (mk_eq_refl h) is a more efficient version of (mk_app `eq.refl [h]) -/
meta constant mk_eq_refl : expr → tactic expr
/-- (mk_eq_symm h) is a more efficient version of (mk_app `eq.symm [h]) -/
meta constant mk_eq_symm : expr → tactic expr
/-- (mk_eq_trans h₁ h₂) is a more efficient version of (mk_app `eq.trans [h₁, h₂]) -/
meta constant mk_eq_trans : expr → expr → tactic expr
/-- (mk_eq_mp h₁ h₂) is a more efficient version of (mk_app `eq.mp [h₁, h₂]) -/
meta constant mk_eq_mp : expr → expr → tactic expr
/-- (mk_eq_mpr h₁ h₂) is a more efficient version of (mk_app `eq.mpr [h₁, h₂]) -/
meta constant mk_eq_mpr : expr → expr → tactic expr
/- Given a local constant t, if t has type (lhs = rhs) apply susbstitution.
Otherwise, try to find a local constant that has type of the form (t = t') or (t' = t).
The tactic fails if the given expression is not a local constant. -/
meta constant subst : expr → tactic unit
/-- Close the current goal using `e`. Fail is the type of `e` is not definitionally equal to
the target type. -/
meta constant exact (e : expr) (md := semireducible) : tactic unit
/-- Elaborate the given quoted expression with respect to the current main goal.
If `allow_mvars` is tt, then metavariables are tolerated and become new goals.
If `report_errors` is ff, then errors are reported using position information from q. -/
meta constant to_expr (q : pexpr) (allow_mvars := tt) (report_errors := ff) : tactic expr
/- Return true if the given expression is a type class. -/
meta constant is_class : expr → tactic bool
/- Try to create an instance of the given type class. -/
meta constant mk_instance : expr → tactic expr
/- Change the target of the main goal.
The input expression must be definitionally equal to the current target. -/
meta constant change : expr → tactic unit
/- (assert_core H T), adds a new goal for T, and change target to (T -> target). -/
meta constant assert_core : name → expr → tactic unit
/- (assertv_core H T P), change target to (T -> target) if P has type T. -/
meta constant assertv_core : name → expr → expr → tactic unit
/- (define_core H T), adds a new goal for T, and change target to (let H : T := ?M in target) in the current goal. -/
meta constant define_core : name → expr → tactic unit
/- (definev_core H T P), change target to (Let H : T := P in target) if P has type T. -/
meta constant definev_core : name → expr → expr → tactic unit
/- rotate goals to the left -/
meta constant rotate_left : nat → tactic unit
meta constant get_goals : tactic (list expr)
meta constant set_goals : list expr → tactic unit
/-- Configuration options for the `apply` tactic. -/
structure apply_cfg :=
(md := semireducible)
(approx := tt)
(all := ff)
(use_instances := tt)
/-- Apply the expression `e` to the main goal,
the unification is performed using the transparency mode in `cfg`.
If cfg^.approx is `tt`, then fallback to first-order unification, and approximate context during unification.
If cfg^.all is `tt`, then all unassigned meta-variables are added as new goals.
If cfg^.use_instances is `tt`, then use type class resolution to instantiate unassigned meta-variables.
It returns a list of all introduced meta variables, even the assigned ones. -/
meta constant apply_core (e : expr) (cfg : apply_cfg := {}) : tactic (list expr)
/- Create a fresh meta universe variable. -/
meta constant mk_meta_univ : tactic level
/- Create a fresh meta-variable with the given type.
The scope of the new meta-variable is the local context of the main goal. -/
meta constant mk_meta_var : expr → tactic expr
/- Return the value assigned to the given universe meta-variable.
Fail if argument is not an universe meta-variable or if it is not assigned. -/
meta constant get_univ_assignment : level → tactic level
/- Return the value assigned to the given meta-variable.
Fail if argument is not a meta-variable or if it is not assigned. -/
meta constant get_assignment : expr → tactic expr
meta constant mk_fresh_name : tactic name
/- Return a hash code for expr that ignores inst_implicit arguments,
and proofs. -/
meta constant abstract_hash : expr → tactic nat
/- Return the "weight" of the given expr while ignoring inst_implicit arguments,
and proofs. -/
meta constant abstract_weight : expr → tactic nat
meta constant abstract_eq : expr → expr → tactic bool
/- Induction on `h` using recursor `rec`, names for the new hypotheses
are retrieved from `ns`. If `ns` does not have sufficient names, then use the internal binder names
in the recursor.
It returns for each new goal a list of new hypotheses and a list of substitutions for hypotheses
depending on `h`. The substitutions map internal names to their replacement terms. If the
replacement is again a hypothesis the user name stays the same. The internal names are only valid
in the original goal, not in the type context of the new goal.
If `rec` is none, then the type of `h` is inferred, if it is of the form `C ...`, tactic uses `C.rec` -/
meta constant induction (h : expr) (ns : list name := []) (rec : option name := none) (md := semireducible) : tactic (list (list expr × list (name × expr)))
/- Apply `cases_on` recursor, names for the new hypotheses are retrieved from `ns`.
`h` must be a local constant. It returns for each new goal the name of the constructor, a list of new hypotheses, and a list of
substitutions for hypotheses depending on `h`. The number of new goals may be smaller than the
number of constructors. Some goals may be discarded when the indices to not match.
See `induction` for information on the list of substitutions.
The `cases` tactic is implemented using this one, and it relaxes the restriction of `h`. -/
meta constant cases_core (h : expr) (ns : list name := []) (md := semireducible) : tactic (list (name × list expr × list (name × expr)))
/- Similar to cases tactic, but does not revert/intro/clear hypotheses. -/
meta constant destruct (e : expr) (md := semireducible) : tactic unit
/- Generalizes the target with respect to `e`. -/
meta constant generalize (e : expr) (n : name := `_x) (md := semireducible) : tactic unit
/- instantiate assigned metavariables in the given expression -/
meta constant instantiate_mvars : expr → tactic expr
/- Add the given declaration to the environment -/
meta constant add_decl : declaration → tactic unit
/- (doc_string env d k) return the doc string for d (if available) -/
meta constant doc_string : name → tactic string
meta constant add_doc_string : name → string → tactic unit
/--
Create an auxiliary definition with name `c` where `type` and `value` may contain local constants and
meta-variables. This function collects all dependencies (universe parameters, universe metavariables,
local constants (aka hypotheses) and metavariables).
It updates the environment in the tactic_state, and returns an expression of the form
(c.{l_1 ... l_n} a_1 ... a_m)
where l_i's and a_j's are the collected dependencies.
-/
meta constant add_aux_decl (c : name) (type : expr) (val : expr) (is_lemma : bool) : tactic expr
meta constant module_doc_strings : tactic (list (option name × string))
/- Set attribute `attr_name` for constant `c_name` with the given priority.
If the priority is none, then use default -/
meta constant set_basic_attribute (attr_name : name) (c_name : name) (persistent := ff) (prio : option nat := none) : tactic unit
/- (unset_attribute attr_name c_name) -/
meta constant unset_attribute : name → name → tactic unit
/- (has_attribute attr_name c_name) succeeds if the declaration `decl_name`
has the attribute `attr_name`. The result is the priority. -/
meta constant has_attribute : name → name → tactic nat
/- (copy_attribute attr_name c_name d_name) copy attribute `attr_name` from
`src` to `tgt` if it is defined for `src` -/
meta def copy_attribute (attr_name : name) (src : name) (p : bool) (tgt : name) : tactic unit :=
try $ do
prio ← has_attribute attr_name src,
set_basic_attribute attr_name tgt p (some prio)
/-- Name of the declaration currently being elaborated. -/
meta constant decl_name : tactic name
/- (save_type_info e ref) save (typeof e) at position associated with ref -/
meta constant save_type_info : expr → expr → tactic unit
meta constant save_info_thunk : pos → (unit → format) → tactic unit
meta constant report_error : nat → nat → format → tactic unit
/-- Return list of currently open namespaces -/
meta constant open_namespaces : tactic (list name)
/-- Return tt iff `t` "occurs" in `e`. The occurrence checking is performed using
keyed matching with the given transparency setting.
We say `t` occurs in `e` by keyed matching iff there is a subterm `s`
s.t. `t` and `s` have the same head, and `is_def_eq t s md`
The main idea is to minimize the number of `is_def_eq` checks
performed. -/
meta constant kdepends_on (e t : expr) (md := reducible) : tactic bool
open list nat
meta def induction' (h : expr) (ns : list name := []) (rec : option name := none) (md := semireducible) : tactic unit :=
induction h ns rec md >> return ()
/-- Remark: set_goals will erase any solved goal -/
meta def cleanup : tactic unit :=
get_goals >>= set_goals
/- Auxiliary definition used to implement begin ... end blocks -/
meta def step {α : Type u} (t : tactic α) : tactic unit :=
t >>[tactic] cleanup
meta def istep {α : Type u} (line : nat) (col : nat) (t : tactic α) : tactic unit :=
λ s, @scope_trace _ line col ((t >>[tactic] cleanup) s)
meta def report_exception {α : Type} (line col : nat) : option (unit → format) → tactic α
| (some msg_thunk) := λ s,
let msg := msg_thunk () ++ format.line ++ to_fmt "state:" ++ format.line ++ s^.to_format in
(tactic.report_error line col msg >> silent_fail) s
| none := silent_fail
/- Auxiliary definition used to implement begin ... end blocks.
It is similar to step, but it reports an error at the given line/col if the tactic t fails. -/
meta def rstep {α : Type u} (line : nat) (col : nat) (t : tactic α) : tactic unit :=
λ s, result.cases_on (istep line col t s)
(λ a new_s, result.success () new_s)
(λ msg_thunk e, report_exception line col msg_thunk)
meta def is_prop (e : expr) : tactic bool :=
do t ← infer_type e,
return (t = expr.prop)
/-- Return true iff n is the name of declaration that is a proposition. -/
meta def is_prop_decl (n : name) : tactic bool :=
do env ← get_env,
d ← env^.get n,
t ← return $ d^.type,
is_prop t
meta def is_proof (e : expr) : tactic bool :=
infer_type e >>= is_prop
meta def whnf_no_delta (e : expr) : tactic expr :=
whnf e transparency.none
meta def whnf_target : tactic unit :=
target >>= whnf >>= change
meta def intro (n : name) : tactic expr :=
do t ← target,
if expr.is_pi t ∨ expr.is_let t then intro_core n
else whnf_target >> intro_core n
meta def intro1 : tactic expr :=
intro `_
meta def intros : tactic (list expr) :=
do t ← target,
match t with
| expr.pi _ _ _ _ := do H ← intro1, Hs ← intros, return (H :: Hs)
| expr.elet _ _ _ _ := do H ← intro1, Hs ← intros, return (H :: Hs)
| _ := return []
end
meta def intro_lst : list name → tactic (list expr)
| [] := return []
| (n::ns) := do H ← intro n, Hs ← intro_lst ns, return (H :: Hs)
meta def to_expr_strict (q : pexpr) (report_errors := ff) : tactic expr :=
to_expr q report_errors
meta def revert (l : expr) : tactic nat :=
revert_lst [l]
meta def clear_lst : list name → tactic unit
| [] := skip
| (n::ns) := do H ← get_local n, clear H, clear_lst ns
meta def match_not (e : expr) : tactic expr :=
match (expr.is_not e) with
| (some a) := return a
| none := fail "expression is not a negation"
end
meta def match_eq (e : expr) : tactic (expr × expr) :=
match (expr.is_eq e) with
| (some (lhs, rhs)) := return (lhs, rhs)
| none := fail "expression is not an equality"
end
meta def match_ne (e : expr) : tactic (expr × expr) :=
match (expr.is_ne e) with
| (some (lhs, rhs)) := return (lhs, rhs)
| none := fail "expression is not a disequality"
end
meta def match_heq (e : expr) : tactic (expr × expr × expr × expr) :=
do match (expr.is_heq e) with
| (some (α, lhs, β, rhs)) := return (α, lhs, β, rhs)
| none := fail "expression is not a heterogeneous equality"
end
meta def match_refl_app (e : expr) : tactic (name × expr × expr) :=
do env ← get_env,
match (environment.is_refl_app env e) with
| (some (R, lhs, rhs)) := return (R, lhs, rhs)
| none := fail "expression is not an application of a reflexive relation"
end
meta def match_app_of (e : expr) (n : name) : tactic (list expr) :=
guard (expr.is_app_of e n) >> return e^.get_app_args
meta def get_local_type (n : name) : tactic expr :=
get_local n >>= infer_type
meta def trace_result : tactic unit :=
format_result >>= trace
meta def rexact (e : expr) : tactic unit :=
exact e reducible
/- (find_same_type t es) tries to find in es an expression with type definitionally equal to t -/
meta def find_same_type : expr → list expr → tactic expr
| e [] := failed
| e (H :: Hs) :=
do t ← infer_type H,
(unify e t >> return H) <|> find_same_type e Hs
meta def find_assumption (e : expr) : tactic expr :=
do ctx ← local_context, find_same_type e ctx
meta def assumption : tactic unit :=
do { ctx ← local_context,
t ← target,
H ← find_same_type t ctx,
exact H }
<|> fail "assumption tactic failed"
meta def save_info (p : pos) : tactic unit :=
do s ← read,
tactic.save_info_thunk p (λ _, tactic_state.to_format s)
notation `‹` p `›` := show p, by assumption
/- Swap first two goals, do nothing if tactic state does not have at least two goals. -/
meta def swap : tactic unit :=
do gs ← get_goals,
match gs with
| (g₁ :: g₂ :: rs) := set_goals (g₂ :: g₁ :: rs)
| e := skip
end
/- (assert h t), adds a new goal for t, and the hypothesis (h : t) in the current goal. -/
meta def assert (h : name) (t : expr) : tactic unit :=
assert_core h t >> swap >> intro h >> swap
/- (assertv h t v), adds the hypothesis (h : t) in the current goal if v has type t. -/
meta def assertv (h : name) (t : expr) (v : expr) : tactic unit :=
assertv_core h t v >> intro h >> return ()
/- (define h t), adds a new goal for t, and the hypothesis (h : t := ?M) in the current goal. -/
meta def define (h : name) (t : expr) : tactic unit :=
define_core h t >> swap >> intro h >> swap
/- (definev h t v), adds the hypothesis (h : t := v) in the current goal if v has type t. -/
meta def definev (h : name) (t : expr) (v : expr) : tactic unit :=
definev_core h t v >> intro h >> return ()
/- Add (h : t := pr) to the current goal -/
meta def pose (h : name) (pr : expr) : tactic unit :=
do t ← infer_type pr,
definev h t pr
/- Add (h : t) to the current goal, given a proof (pr : t) -/
meta def note (n : name) (pr : expr) : tactic unit :=
do t ← infer_type pr,
assertv n t pr
/- Return the number of goals that need to be solved -/
meta def num_goals : tactic nat :=
do gs ← get_goals,
return (length gs)
/- We have to provide the instance argument `[has_mod nat]` because
mod for nat was not defined yet -/
meta def rotate_right (n : nat) [has_mod nat] : tactic unit :=
do ng ← num_goals,
if ng = 0 then skip
else rotate_left (ng - n % ng)
meta def rotate : nat → tactic unit :=
rotate_left
/- first [t_1, ..., t_n] applies the first tactic that doesn't fail.
The tactic fails if all t_i's fail. -/
meta def first {α : Type u} : list (tactic α) → tactic α
| [] := fail "first tactic failed, no more alternatives"
| (t::ts) := t <|> first ts
/- Applies the given tactic to the main goal and fails if it is not solved. -/
meta def solve1 (tac : tactic unit) : tactic unit :=
do gs ← get_goals,
match gs with
| [] := fail "focus tactic failed, there isn't any goal left to focus"
| (g::rs) :=
do set_goals [g],
tac,
gs' ← get_goals,
match gs' with
| [] := set_goals rs
| gs := fail "focus tactic failed, focused goal has not been solved"
end
end
/- solve [t_1, ... t_n] applies the first tactic that solves the main goal. -/
meta def solve (ts : list (tactic unit)) : tactic unit :=
first $ map solve1 ts
private meta def focus_aux : list (tactic unit) → list expr → list expr → tactic unit
| [] gs rs := set_goals $ rs ++ gs
| (t::ts) (g::gs) rs := do
set_goals [g], t, rs' ← get_goals,
focus_aux ts gs (rs ++ rs')
| (t::ts) [] rs := fail "focus tactic failed, insufficient number of goals"
/- focus [t_1, ..., t_n] applies t_i to the i-th goal. Fails if there are less tha n goals. -/
meta def focus (ts : list (tactic unit)) : tactic unit :=
do gs ← get_goals, focus_aux ts gs []
meta def focus1 {α} (tac : tactic α) : tactic α :=
do g::gs ← get_goals,
match gs with
| [] := tac
| _ := do
set_goals [g],
a ← tac,
gs' ← get_goals,
set_goals (gs' ++ gs),
return a
end
private meta def all_goals_core (tac : tactic unit) : list expr → list expr → tactic unit
| [] ac := set_goals ac
| (g :: gs) ac :=
do set_goals [g],
tac,
new_gs ← get_goals,
all_goals_core gs (ac ++ new_gs)
/- Apply the given tactic to all goals. -/
meta def all_goals (tac : tactic unit) : tactic unit :=
do gs ← get_goals,
all_goals_core tac gs []
private meta def any_goals_core (tac : tactic unit) : list expr → list expr → bool → tactic unit
| [] ac progress := guard progress >> set_goals ac
| (g :: gs) ac progress :=
do set_goals [g],
succeeded ← try_core tac,
new_gs ← get_goals,
any_goals_core gs (ac ++ new_gs) (succeeded^.is_some || progress)
/- Apply the given tactic to any goal where it succeeds. The tactic succeeds only if
tac succeeds for at least one goal. -/
meta def any_goals (tac : tactic unit) : tactic unit :=
do gs ← get_goals,
any_goals_core tac gs [] ff
/- LCF-style AND_THEN tactic. It applies tac1, and if succeed applies tac2 to each subgoal produced by tac1 -/
meta def seq (tac1 : tactic unit) (tac2 : tactic unit) : tactic unit :=
do g::gs ← get_goals,
set_goals [g],
tac1, all_goals tac2,
gs' ← get_goals,
set_goals (gs' ++ gs)
meta instance : has_andthen (tactic unit) :=
⟨seq⟩
meta constant is_trace_enabled_for : name → bool
/- Execute tac only if option trace.n is set to true. -/
meta def when_tracing (n : name) (tac : tactic unit) : tactic unit :=
when (is_trace_enabled_for n = tt) tac
/- Fail if there are no remaining goals. -/
meta def fail_if_no_goals : tactic unit :=
do n ← num_goals,
when (n = 0) (fail "tactic failed, there are no goals to be solved")
/- Fail if there are unsolved goals. -/
meta def now : tactic unit :=
do n ← num_goals,
when (n ≠ 0) (fail "now tactic failed, there are unsolved goals")
meta def apply (e : expr) : tactic unit :=
apply_core e >> return ()
meta def fapply (e : expr) : tactic unit :=
apply_core e {all := tt} >> return ()
/- Try to solve the main goal using type class resolution. -/
meta def apply_instance : tactic unit :=
do tgt ← target >>= instantiate_mvars,
b ← is_class tgt,
if b then mk_instance tgt >>= exact
else fail "apply_instance tactic fail, target is not a type class"
/- Create a list of universe meta-variables of the given size. -/
meta def mk_num_meta_univs : nat → tactic (list level)
| 0 := return []
| (succ n) := do
l ← mk_meta_univ,
ls ← mk_num_meta_univs n,
return (l::ls)
/- Return (expr.const c [l_1, ..., l_n]) where l_i's are fresh universe meta-variables. -/
meta def mk_const (c : name) : tactic expr :=
do env ← get_env,
decl ← env^.get c,
let num := decl^.univ_params^.length,
ls ← mk_num_meta_univs num,
return (expr.const c ls)
meta def save_const_type_info (n : name) (ref : expr) : tactic unit :=
try (do c ← mk_const n, save_type_info c ref)
/- Create a fresh universe ?u, a metavariable (?T : Type.{?u}),
and return metavariable (?M : ?T).
This action can be used to create a meta-variable when
we don't know its type at creation time -/
meta def mk_mvar : tactic expr :=
do u ← mk_meta_univ,
t ← mk_meta_var (expr.sort u),
mk_meta_var t
/-- Makes a sorry macro with a meta-variable as its type. -/
meta def mk_sorry : tactic expr := do
u ← mk_meta_univ,
t ← mk_meta_var (expr.sort u),
return $ expr.mk_sorry t
/-- Closes the main goal using sorry. -/
meta def admit : tactic unit :=
target >>= exact ∘ expr.mk_sorry
meta def mk_local' (pp_name : name) (bi : binder_info) (type : expr) : tactic expr := do
uniq_name ← mk_fresh_name,
return $ expr.local_const uniq_name pp_name bi type
meta def mk_local_def (pp_name : name) (type : expr) : tactic expr :=
mk_local' pp_name binder_info.default type
private meta def get_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_pi_arity_aux new_b,
return (r + 1)
| e := return 0
/- Compute the arity of the given (Pi-)type -/
meta def get_pi_arity (type : expr) : tactic nat :=
whnf type >>= get_pi_arity_aux
/- Compute the arity of the given function -/
meta def get_arity (fn : expr) : tactic nat :=
infer_type fn >>= get_pi_arity
meta def triv : tactic unit := mk_const `trivial >>= exact
notation `dec_trivial` := of_as_true (by tactic.triv)
meta def by_contradiction (H : name) : tactic expr :=
do tgt : expr ← target,
(match_not tgt >> return ())
<|>
(mk_mapp `decidable.by_contradiction [some tgt, none] >>= apply)
<|>
fail "tactic by_contradiction failed, target is not a negation nor a decidable proposition (remark: when 'local attribute classical.prop_decidable [instance]' is used all propositions are decidable)",
intro H
private meta def generalizes_aux (md : transparency) : list expr → tactic unit
| [] := skip
| (e::es) := generalize e `x md >> generalizes_aux es
meta def generalizes (es : list expr) (md := semireducible) : tactic unit :=
generalizes_aux md es
private meta def kdependencies_core (e : expr) (md : transparency) : list expr → list expr → tactic (list expr)
| [] r := return r
| (h::hs) r :=
do type ← infer_type h,
d ← kdepends_on type e md,
if d then kdependencies_core hs (h::r)
else kdependencies_core hs r
/-- Return all hypotheses that depends on `e`
The dependency test is performed using `kdepends_on` with the given transparency setting. -/
meta def kdependencies (e : expr) (md := reducible) : tactic (list expr) :=
do ctx ← local_context, kdependencies_core e md ctx []
/-- Revert all hypotheses that depend on `e` -/
meta def revert_kdependencies (e : expr) (md := reducible) : tactic nat :=
kdependencies e md >>= revert_lst
meta def revert_kdeps (e : expr) (md := reducible) :=
revert_kdependencies e md
/-- Similar to `cases_core`, but `e` doesn't need to be a hypothesis.
Remark, it reverts dependencies using `revert_kdeps`.
Two different transparency modes are used `md` and `dmd`.
The mode `md` is used with `cases_core` and `dmd` with `generalize` and `revert_kdeps`. -/
meta def cases (e : expr) (ids : list name := []) (md := semireducible) (dmd := semireducible) : tactic unit :=
if e^.is_local_constant then
cases_core e ids md >> return ()
else do
x ← mk_fresh_name,
n ← revert_kdependencies e dmd,
(tactic.generalize e x dmd)
<|>
(do t ← infer_type e,
tactic.assertv x t e,
get_local x >>= tactic.revert,
return ()),
h ← tactic.intro1,
(step (cases_core h ids md); intron n)
meta def refine (e : pexpr) (report_errors := ff) : tactic unit :=
do tgt : expr ← target,
to_expr ``(%%e : %%tgt) tt report_errors >>= exact
private meta def get_undeclared_const (env : environment) (base : name) : ℕ → name | i :=
let n := base <.> ("_aux_" ++ to_string i) in
if ¬env^.contains n then n
else get_undeclared_const (i+1)
meta def new_aux_decl_name : tactic name := do
env ← get_env, n ← decl_name,
return $ get_undeclared_const env n 1
private meta def mk_aux_decl_name : option name → tactic name
| none := new_aux_decl_name
| (some suffix) := do p ← decl_name, return $ p ++ suffix
meta def abstract (tac : tactic unit) (suffix : option name := none) : tactic unit :=
do fail_if_no_goals,
gs ← get_goals,
type ← target,
is_lemma ← is_prop type,
m ← mk_meta_var type,
set_goals [m],
tac,
n ← num_goals,
when (n ≠ 0) (fail "abstract tactic failed, there are unsolved goals"),
set_goals gs,
val ← instantiate_mvars m,
c ← mk_aux_decl_name suffix,
e ← add_aux_decl c type val is_lemma,
exact e
/- (solve_aux type tac) synthesize an element of 'type' using tactic 'tac' -/
meta def solve_aux {α : Type} (type : expr) (tac : tactic α) : tactic (α × expr) :=
do m ← mk_meta_var type,
gs ← get_goals,
set_goals [m],
a ← tac,
set_goals gs,
return (a, m)
/-- Return tt iff 'd' is a declaration in one of the current open namespaces -/
meta def in_open_namespaces (d : name) : tactic bool :=
do ns ← open_namespaces,
env ← get_env,
return $ ns^.any (λ n, n^.is_prefix_of d) && env^.contains d
/-- Execute tac for 'max' "heartbeats". The heartbeat is approx. the maximum number of
memory allocations (in thousands) performed by 'tac'. This is a deterministic way of interrupting
long running tactics. -/
meta def try_for {α} (max : nat) (tac : tactic α) : tactic α :=
λ s,
match _root_.try_for max (tac s) with
| some r := r
| none := mk_exception "try_for tactic failed, timeout" none s
end
meta def add_meta_definition (n : name) (lvls : list name) (type value : expr) : tactic unit :=
add_decl (declaration.defn n lvls type value reducibility_hints.abbrev ff)
end tactic
notation [parsing_only] `command`:max := tactic unit
open tactic
namespace list
meta def for_each {α} : list α → (α → tactic unit) → tactic unit
| [] fn := skip
| (e::es) fn := do fn e, for_each es fn
meta def any_of {α β} : list α → (α → tactic β) → tactic β
| [] fn := failed
| (e::es) fn := do opt_b ← try_core (fn e),
match opt_b with
| some b := return b
| none := any_of es fn
end
end list
/-
Define id_locked using meta-programming because we don't have
syntax for setting reducibility_hints.
See module init.meta.declaration.
Remark: id_locked is used in the builtin implementation of tactic.change
-/
run_command do
let l := level.param `l,
let Ty := expr.sort l,
type ← to_expr ``(Π (α : %%Ty), α → α),
val ← to_expr ``(λ (α : %%Ty) (a : α), a),
add_decl (declaration.defn `id_locked [`l] type val reducibility_hints.opaque tt)
lemma id_locked_eq {α : Type u} (a : α) : id_locked α a = a :=
rfl
|
778179924733a084184d168b1f5b241028108a63 | 8cb37a089cdb4af3af9d8bf1002b417e407a8e9e | /library/data/stream.lean | 88a157d4770b40f125f797d6b87a878c94570ecb | [
"Apache-2.0"
] | permissive | kbuzzard/lean | ae3c3db4bb462d750dbf7419b28bafb3ec983ef7 | ed1788fd674bb8991acffc8fca585ec746711928 | refs/heads/master | 1,620,983,366,617 | 1,618,937,600,000 | 1,618,937,600,000 | 359,886,396 | 1 | 0 | Apache-2.0 | 1,618,936,987,000 | 1,618,936,987,000 | null | UTF-8 | Lean | false | false | 21,705 | lean | /-
Copyright (c) 2015 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
-/
open nat function option
universes u v w
def stream (α : Type u) := nat → α
namespace stream
variables {α : Type u} {β : Type v} {δ : Type w}
def cons (a : α) (s : stream α) : stream α :=
λ i,
match i with
| 0 := a
| succ n := s n
end
notation h :: t := cons h t
@[reducible] def head (s : stream α) : α :=
s 0
def tail (s : stream α) : stream α :=
λ i, s (i+1)
def drop (n : nat) (s : stream α) : stream α :=
λ i, s (i+n)
@[reducible] def nth (n : nat) (s : stream α) : α :=
s n
protected theorem eta (s : stream α) : head s :: tail s = s :=
funext (λ i, begin cases i; refl end)
theorem nth_zero_cons (a : α) (s : stream α) : nth 0 (a :: s) = a := rfl
theorem head_cons (a : α) (s : stream α) : head (a :: s) = a := rfl
theorem tail_cons (a : α) (s : stream α) : tail (a :: s) = s := rfl
theorem tail_drop (n : nat) (s : stream α) : tail (drop n s) = drop n (tail s) :=
funext (λ i, begin unfold tail drop, simp [nat.add_comm, nat.add_left_comm] end)
theorem nth_drop (n m : nat) (s : stream α) : nth n (drop m s) = nth (n+m) s := rfl
theorem tail_eq_drop (s : stream α) : tail s = drop 1 s := rfl
theorem drop_drop (n m : nat) (s : stream α) : drop n (drop m s) = drop (n+m) s :=
funext (λ i, begin unfold drop, rw nat.add_assoc end)
theorem nth_succ (n : nat) (s : stream α) : nth (succ n) s = nth n (tail s) := rfl
theorem drop_succ (n : nat) (s : stream α) : drop (succ n) s = drop n (tail s) := rfl
protected theorem ext {s₁ s₂ : stream α} : (∀ n, nth n s₁ = nth n s₂) → s₁ = s₂ :=
assume h, funext h
def all (p : α → Prop) (s : stream α) := ∀ n, p (nth n s)
def any (p : α → Prop) (s : stream α) := ∃ n, p (nth n s)
theorem all_def (p : α → Prop) (s : stream α) : all p s = ∀ n, p (nth n s) := rfl
theorem any_def (p : α → Prop) (s : stream α) : any p s = ∃ n, p (nth n s) := rfl
protected def mem (a : α) (s : stream α) := any (λ b, a = b) s
instance : has_mem α (stream α) :=
⟨stream.mem⟩
theorem mem_cons (a : α) (s : stream α) : a ∈ (a::s) :=
exists.intro 0 rfl
theorem mem_cons_of_mem {a : α} {s : stream α} (b : α) : a ∈ s → a ∈ b :: s :=
assume ⟨n, h⟩,
exists.intro (succ n) (by rw [nth_succ, tail_cons, h])
theorem eq_or_mem_of_mem_cons {a b : α} {s : stream α} : a ∈ b::s → a = b ∨ a ∈ s :=
assume ⟨n, h⟩,
begin
cases n with n',
{left, exact h},
{right, rw [nth_succ, tail_cons] at h, exact ⟨n', h⟩}
end
theorem mem_of_nth_eq {n : nat} {s : stream α} {a : α} : a = nth n s → a ∈ s :=
assume h, exists.intro n h
section map
variable (f : α → β)
def map (s : stream α) : stream β :=
λ n, f (nth n s)
theorem drop_map (n : nat) (s : stream α) : drop n (map f s) = map f (drop n s) :=
stream.ext (λ i, rfl)
theorem nth_map (n : nat) (s : stream α) : nth n (map f s) = f (nth n s) := rfl
theorem tail_map (s : stream α) : tail (map f s) = map f (tail s) :=
begin rw tail_eq_drop, refl end
theorem head_map (s : stream α) : head (map f s) = f (head s) := rfl
theorem map_eq (s : stream α) : map f s = f (head s) :: map f (tail s) :=
by rw [← stream.eta (map f s), tail_map, head_map]
theorem map_cons (a : α) (s : stream α) : map f (a :: s) = f a :: map f s :=
begin rw [← stream.eta (map f (a :: s)), map_eq], refl end
theorem map_id (s : stream α) : map id s = s := rfl
theorem map_map (g : β → δ) (f : α → β) (s : stream α) : map g (map f s) = map (g ∘ f) s := rfl
theorem map_tail (s : stream α) : map f (tail s) = tail (map f s) := rfl
theorem mem_map {a : α} {s : stream α} : a ∈ s → f a ∈ map f s :=
assume ⟨n, h⟩,
exists.intro n (by rw [nth_map, h])
theorem exists_of_mem_map {f} {b : β} {s : stream α} : b ∈ map f s → ∃ a, a ∈ s ∧ f a = b :=
assume ⟨n, h⟩, ⟨nth n s, ⟨n, rfl⟩, h.symm⟩
end map
section zip
variable (f : α → β → δ)
def zip (s₁ : stream α) (s₂ : stream β) : stream δ :=
λ n, f (nth n s₁) (nth n s₂)
theorem drop_zip (n : nat) (s₁ : stream α) (s₂ : stream β) : drop n (zip f s₁ s₂) = zip f (drop n s₁) (drop n s₂) :=
stream.ext (λ i, rfl)
theorem nth_zip (n : nat) (s₁ : stream α) (s₂ : stream β) : nth n (zip f s₁ s₂) = f (nth n s₁) (nth n s₂) := rfl
theorem head_zip (s₁ : stream α) (s₂ : stream β) : head (zip f s₁ s₂) = f (head s₁) (head s₂) := rfl
theorem tail_zip (s₁ : stream α) (s₂ : stream β) : tail (zip f s₁ s₂) = zip f (tail s₁) (tail s₂) := rfl
theorem zip_eq (s₁ : stream α) (s₂ : stream β) : zip f s₁ s₂ = f (head s₁) (head s₂) :: zip f (tail s₁) (tail s₂) :=
begin rw [← stream.eta (zip f s₁ s₂)], refl end
end zip
def const (a : α) : stream α :=
λ n, a
theorem mem_const (a : α) : a ∈ const a :=
exists.intro 0 rfl
theorem const_eq (a : α) : const a = a :: const a :=
begin
apply stream.ext, intro n,
cases n; refl
end
theorem tail_const (a : α) : tail (const a) = const a :=
suffices tail (a :: const a) = const a, by rwa [← const_eq] at this, rfl
theorem map_const (f : α → β) (a : α) : map f (const a) = const (f a) := rfl
theorem nth_const (n : nat) (a : α) : nth n (const a) = a := rfl
theorem drop_const (n : nat) (a : α) : drop n (const a) = const a :=
stream.ext (λ i, rfl)
def iterate (f : α → α) (a : α) : stream α :=
λ n, nat.rec_on n a (λ n r, f r)
theorem head_iterate (f : α → α) (a : α) : head (iterate f a) = a := rfl
theorem tail_iterate (f : α → α) (a : α) : tail (iterate f a) = iterate f (f a) :=
begin
funext n,
induction n with n' ih,
{refl},
{unfold tail iterate,
unfold tail iterate at ih,
rw add_one at ih, dsimp at ih,
rw add_one, dsimp, rw ih}
end
theorem iterate_eq (f : α → α) (a : α) : iterate f a = a :: iterate f (f a) :=
begin
rw [← stream.eta (iterate f a)],
rw tail_iterate, refl
end
theorem nth_zero_iterate (f : α → α) (a : α) : nth 0 (iterate f a) = a := rfl
theorem nth_succ_iterate (n : nat) (f : α → α) (a : α) : nth (succ n) (iterate f a) = nth n (iterate f (f a)) :=
by rw [nth_succ, tail_iterate]
section bisim
variable (R : stream α → stream α → Prop)
local infix ~ := R
def is_bisimulation := ∀ ⦃s₁ s₂⦄, s₁ ~ s₂ → head s₁ = head s₂ ∧ tail s₁ ~ tail s₂
theorem nth_of_bisim (bisim : is_bisimulation R) : ∀ {s₁ s₂} n, s₁ ~ s₂ → nth n s₁ = nth n s₂ ∧ drop (n+1) s₁ ~ drop (n+1) s₂
| s₁ s₂ 0 h := bisim h
| s₁ s₂ (n+1) h :=
match bisim h with
| ⟨h₁, trel⟩ := nth_of_bisim n trel
end
-- If two streams are bisimilar, then they are equal
theorem eq_of_bisim (bisim : is_bisimulation R) : ∀ {s₁ s₂}, s₁ ~ s₂ → s₁ = s₂ :=
λ s₁ s₂ r, stream.ext (λ n, and.elim_left (nth_of_bisim R bisim n r))
end bisim
theorem bisim_simple (s₁ s₂ : stream α) : head s₁ = head s₂ → s₁ = tail s₁ → s₂ = tail s₂ → s₁ = s₂ :=
assume hh ht₁ ht₂, eq_of_bisim
(λ s₁ s₂, head s₁ = head s₂ ∧ s₁ = tail s₁ ∧ s₂ = tail s₂)
(λ s₁ s₂ ⟨h₁, h₂, h₃⟩,
begin
constructor, exact h₁, rw [← h₂, ← h₃], repeat { constructor }; assumption
end)
(and.intro hh (and.intro ht₁ ht₂))
theorem coinduction {s₁ s₂ : stream α} :
head s₁ = head s₂ → (∀ (β : Type u) (fr : stream α → β), fr s₁ = fr s₂ → fr (tail s₁) = fr (tail s₂)) → s₁ = s₂ :=
assume hh ht,
eq_of_bisim
(λ s₁ s₂, head s₁ = head s₂ ∧ ∀ (β : Type u) (fr : stream α → β), fr s₁ = fr s₂ → fr (tail s₁) = fr (tail s₂))
(λ s₁ s₂ h,
have h₁ : head s₁ = head s₂, from and.elim_left h,
have h₂ : head (tail s₁) = head (tail s₂), from and.elim_right h α (@head α) h₁,
have h₃ : ∀ (β : Type u) (fr : stream α → β), fr (tail s₁) = fr (tail s₂) → fr (tail (tail s₁)) = fr (tail (tail s₂)), from
λ β fr, and.elim_right h β (λ s, fr (tail s)),
and.intro h₁ (and.intro h₂ h₃))
(and.intro hh ht)
theorem iterate_id (a : α) : iterate id a = const a :=
coinduction
rfl
(λ β fr ch, begin rw [tail_iterate, tail_const], exact ch end)
local attribute [reducible] stream
theorem map_iterate (f : α → α) (a : α) : iterate f (f a) = map f (iterate f a) :=
begin
funext n,
induction n with n' ih,
{refl},
{ unfold map iterate nth, dsimp,
unfold map iterate nth at ih, dsimp at ih,
rw ih }
end
section corec
def corec (f : α → β) (g : α → α) : α → stream β :=
λ a, map f (iterate g a)
def corec_on (a : α) (f : α → β) (g : α → α) : stream β :=
corec f g a
theorem corec_def (f : α → β) (g : α → α) (a : α) : corec f g a = map f (iterate g a) := rfl
theorem corec_eq (f : α → β) (g : α → α) (a : α) : corec f g a = f a :: corec f g (g a) :=
begin rw [corec_def, map_eq, head_iterate, tail_iterate], refl end
theorem corec_id_id_eq_const (a : α) : corec id id a = const a :=
by rw [corec_def, map_id, iterate_id]
theorem corec_id_f_eq_iterate (f : α → α) (a : α) : corec id f a = iterate f a := rfl
end corec
section corec'
def corec' (f : α → β × α) : α → stream β := corec (prod.fst ∘ f) (prod.snd ∘ f)
theorem corec'_eq (f : α → β × α) (a : α) : corec' f a = (f a).1 :: corec' f (f a).2 :=
corec_eq _ _ _
end corec'
-- corec is also known as unfold
def unfolds (g : α → β) (f : α → α) (a : α) : stream β :=
corec g f a
theorem unfolds_eq (g : α → β) (f : α → α) (a : α) : unfolds g f a = g a :: unfolds g f (f a) :=
begin unfold unfolds, rw [corec_eq] end
theorem nth_unfolds_head_tail : ∀ (n : nat) (s : stream α), nth n (unfolds head tail s) = nth n s :=
begin
intro n, induction n with n' ih,
{intro s, refl},
{intro s, rw [nth_succ, nth_succ, unfolds_eq, tail_cons, ih]}
end
theorem unfolds_head_eq : ∀ (s : stream α), unfolds head tail s = s :=
λ s, stream.ext (λ n, nth_unfolds_head_tail n s)
def interleave (s₁ s₂ : stream α) : stream α :=
corec_on (s₁, s₂)
(λ ⟨s₁, s₂⟩, head s₁)
(λ ⟨s₁, s₂⟩, (s₂, tail s₁))
infix `⋈`:65 := interleave
theorem interleave_eq (s₁ s₂ : stream α) : s₁ ⋈ s₂ = head s₁ :: head s₂ :: (tail s₁ ⋈ tail s₂) :=
begin
unfold interleave corec_on, rw corec_eq, dsimp, rw corec_eq, refl
end
theorem tail_interleave (s₁ s₂ : stream α) : tail (s₁ ⋈ s₂) = s₂ ⋈ (tail s₁) :=
begin unfold interleave corec_on, rw corec_eq, refl end
theorem interleave_tail_tail (s₁ s₂ : stream α) : tail s₁ ⋈ tail s₂ = tail (tail (s₁ ⋈ s₂)) :=
begin rw [interleave_eq s₁ s₂], refl end
theorem nth_interleave_left : ∀ (n : nat) (s₁ s₂ : stream α), nth (2*n) (s₁ ⋈ s₂) = nth n s₁
| 0 s₁ s₂ := rfl
| (succ n) s₁ s₂ :=
begin
change nth (succ (succ (2*n))) (s₁ ⋈ s₂) = nth (succ n) s₁,
rw [nth_succ, nth_succ, interleave_eq, tail_cons, tail_cons, nth_interleave_left],
refl
end
theorem nth_interleave_right : ∀ (n : nat) (s₁ s₂ : stream α), nth (2*n+1) (s₁ ⋈ s₂) = nth n s₂
| 0 s₁ s₂ := rfl
| (succ n) s₁ s₂ :=
begin
change nth (succ (succ (2*n+1))) (s₁ ⋈ s₂) = nth (succ n) s₂,
rw [nth_succ, nth_succ, interleave_eq, tail_cons, tail_cons, nth_interleave_right],
refl
end
theorem mem_interleave_left {a : α} {s₁ : stream α} (s₂ : stream α) : a ∈ s₁ → a ∈ s₁ ⋈ s₂ :=
assume ⟨n, h⟩,
exists.intro (2*n) (by rw [h, nth_interleave_left])
theorem mem_interleave_right {a : α} {s₁ : stream α} (s₂ : stream α) : a ∈ s₂ → a ∈ s₁ ⋈ s₂ :=
assume ⟨n, h⟩,
exists.intro (2*n+1) (by rw [h, nth_interleave_right])
def even (s : stream α) : stream α :=
corec
(λ s, head s)
(λ s, tail (tail s))
s
def odd (s : stream α) : stream α :=
even (tail s)
theorem odd_eq (s : stream α) : odd s = even (tail s) := rfl
theorem head_even (s : stream α) : head (even s) = head s := rfl
theorem tail_even (s : stream α) : tail (even s) = even (tail (tail s)) :=
begin unfold even, rw corec_eq, refl end
theorem even_cons_cons (a₁ a₂ : α) (s : stream α) : even (a₁ :: a₂ :: s) = a₁ :: even s :=
begin unfold even, rw corec_eq, refl end
theorem even_tail (s : stream α) : even (tail s) = odd s := rfl
theorem even_interleave (s₁ s₂ : stream α) : even (s₁ ⋈ s₂) = s₁ :=
eq_of_bisim
(λ s₁' s₁, ∃ s₂, s₁' = even (s₁ ⋈ s₂))
(λ s₁' s₁ ⟨s₂, h₁⟩,
begin
rw h₁,
constructor,
{refl},
{exact ⟨tail s₂, by rw [interleave_eq, even_cons_cons, tail_cons]⟩}
end)
(exists.intro s₂ rfl)
theorem interleave_even_odd (s₁ : stream α) : even s₁ ⋈ odd s₁ = s₁ :=
eq_of_bisim
(λ s' s, s' = even s ⋈ odd s)
(λ s' s (h : s' = even s ⋈ odd s),
begin
rw h, constructor,
{refl},
{simp [odd_eq, odd_eq, tail_interleave, tail_even]}
end)
rfl
theorem nth_even : ∀ (n : nat) (s : stream α), nth n (even s) = nth (2*n) s
| 0 s := rfl
| (succ n) s :=
begin
change nth (succ n) (even s) = nth (succ (succ (2 * n))) s,
rw [nth_succ, nth_succ, tail_even, nth_even], refl
end
theorem nth_odd : ∀ (n : nat) (s : stream α), nth n (odd s) = nth (2*n + 1) s :=
λ n s, begin rw [odd_eq, nth_even], refl end
theorem mem_of_mem_even (a : α) (s : stream α) : a ∈ even s → a ∈ s :=
assume ⟨n, h⟩,
exists.intro (2*n) (by rw [h, nth_even])
theorem mem_of_mem_odd (a : α) (s : stream α) : a ∈ odd s → a ∈ s :=
assume ⟨n, h⟩,
exists.intro (2*n+1) (by rw [h, nth_odd])
def append_stream : list α → stream α → stream α
| [] s := s
| (list.cons a l) s := a :: append_stream l s
theorem nil_append_stream (s : stream α) : append_stream [] s = s := rfl
theorem cons_append_stream (a : α) (l : list α) (s : stream α) : append_stream (a::l) s = a :: append_stream l s := rfl
infix `++ₛ`:65 := append_stream
theorem append_append_stream : ∀ (l₁ l₂ : list α) (s : stream α), (l₁ ++ l₂) ++ₛ s = l₁ ++ₛ (l₂ ++ₛ s)
| [] l₂ s := rfl
| (list.cons a l₁) l₂ s := by rw [list.cons_append, cons_append_stream, cons_append_stream, append_append_stream]
theorem map_append_stream (f : α → β) : ∀ (l : list α) (s : stream α), map f (l ++ₛ s) = list.map f l ++ₛ map f s
| [] s := rfl
| (list.cons a l) s := by rw [cons_append_stream, list.map_cons, map_cons, cons_append_stream, map_append_stream]
theorem drop_append_stream : ∀ (l : list α) (s : stream α), drop l.length (l ++ₛ s) = s
| [] s := by refl
| (list.cons a l) s := by rw [list.length_cons, add_one, drop_succ, cons_append_stream, tail_cons, drop_append_stream]
theorem append_stream_head_tail (s : stream α) : [head s] ++ₛ tail s = s :=
by rw [cons_append_stream, nil_append_stream, stream.eta]
theorem mem_append_stream_right : ∀ {a : α} (l : list α) {s : stream α}, a ∈ s → a ∈ l ++ₛ s
| a [] s h := h
| a (list.cons b l) s h :=
have ih : a ∈ l ++ₛ s, from mem_append_stream_right l h,
mem_cons_of_mem _ ih
theorem mem_append_stream_left : ∀ {a : α} {l : list α} (s : stream α), a ∈ l → a ∈ l ++ₛ s
| a [] s h := absurd h (list.not_mem_nil _)
| a (list.cons b l) s h :=
or.elim (list.eq_or_mem_of_mem_cons h)
(λ (aeqb : a = b), exists.intro 0 aeqb)
(λ (ainl : a ∈ l), mem_cons_of_mem b (mem_append_stream_left s ainl))
def approx : nat → stream α → list α
| 0 s := []
| (n+1) s := list.cons (head s) (approx n (tail s))
theorem approx_zero (s : stream α) : approx 0 s = [] := rfl
theorem approx_succ (n : nat) (s : stream α) : approx (succ n) s = head s :: approx n (tail s) := rfl
theorem nth_approx : ∀ (n : nat) (s : stream α), list.nth (approx (succ n) s) n = some (nth n s)
| 0 s := rfl
| (n+1) s := begin rw [approx_succ, add_one, list.nth, nth_approx], refl end
theorem append_approx_drop : ∀ (n : nat) (s : stream α), append_stream (approx n s) (drop n s) = s :=
begin
intro n,
induction n with n' ih,
{intro s, refl},
{intro s, rw [approx_succ, drop_succ, cons_append_stream, ih (tail s), stream.eta]}
end
-- Take theorem reduces a proof of equality of infinite streams to an
-- induction over all their finite approximations.
theorem take_theorem (s₁ s₂ : stream α) : (∀ (n : nat), approx n s₁ = approx n s₂) → s₁ = s₂ :=
begin
intro h, apply stream.ext, intro n,
induction n with n ih,
{ have aux := h 1, simp [approx] at aux, exact aux },
{ have h₁ : some (nth (succ n) s₁) = some (nth (succ n) s₂),
{ rw [← nth_approx, ← nth_approx, h (succ (succ n))] },
injection h₁ }
end
-- auxiliary def for cycle corecursive def
private def cycle_f : α × list α × α × list α → α
| (v, _, _, _) := v
-- auxiliary def for cycle corecursive def
private def cycle_g : α × list α × α × list α → α × list α × α × list α
| (v₁, [], v₀, l₀) := (v₀, l₀, v₀, l₀)
| (v₁, list.cons v₂ l₂, v₀, l₀) := (v₂, l₂, v₀, l₀)
private lemma cycle_g_cons (a : α) (a₁ : α) (l₁ : list α) (a₀ : α) (l₀ : list α) :
cycle_g (a, a₁::l₁, a₀, l₀) = (a₁, l₁, a₀, l₀) := rfl
def cycle : Π (l : list α), l ≠ [] → stream α
| [] h := absurd rfl h
| (list.cons a l) h := corec cycle_f cycle_g (a, l, a, l)
theorem cycle_eq : ∀ (l : list α) (h : l ≠ []), cycle l h = l ++ₛ cycle l h
| [] h := absurd rfl h
| (list.cons a l) h :=
have gen : ∀ l' a', corec cycle_f cycle_g (a', l', a, l) = (a' :: l') ++ₛ corec cycle_f cycle_g (a, l, a, l),
begin
intro l',
induction l' with a₁ l₁ ih,
{intros, rw [corec_eq], refl},
{intros, rw [corec_eq, cycle_g_cons, ih a₁], refl}
end,
gen l a
theorem mem_cycle {a : α} {l : list α} : ∀ (h : l ≠ []), a ∈ l → a ∈ cycle l h :=
assume h ainl, begin rw [cycle_eq], exact mem_append_stream_left _ ainl end
theorem cycle_singleton (a : α) (h : [a] ≠ []) : cycle [a] h = const a :=
coinduction
rfl
(λ β fr ch, by rwa [cycle_eq, const_eq])
def tails (s : stream α) : stream (stream α) :=
corec id tail (tail s)
theorem tails_eq (s : stream α) : tails s = tail s :: tails (tail s) :=
by unfold tails; rw [corec_eq]; refl
theorem nth_tails : ∀ (n : nat) (s : stream α), nth n (tails s) = drop n (tail s) :=
begin
intro n, induction n with n' ih,
{intros, refl},
{intro s, rw [nth_succ, drop_succ, tails_eq, tail_cons, ih]}
end
theorem tails_eq_iterate (s : stream α) : tails s = iterate tail (tail s) := rfl
def inits_core (l : list α) (s : stream α) : stream (list α) :=
corec_on (l, s)
(λ ⟨a, b⟩, a)
(λ p, match p with (l', s') := (l' ++ [head s'], tail s') end)
def inits (s : stream α) : stream (list α) :=
inits_core [head s] (tail s)
theorem inits_core_eq (l : list α) (s : stream α) : inits_core l s = l :: inits_core (l ++ [head s]) (tail s) :=
begin unfold inits_core corec_on, rw [corec_eq], refl end
theorem tail_inits (s : stream α) : tail (inits s) = inits_core [head s, head (tail s)] (tail (tail s)) :=
begin unfold inits, rw inits_core_eq, refl end
theorem inits_tail (s : stream α) : inits (tail s) = inits_core [head (tail s)] (tail (tail s)) := rfl
theorem cons_nth_inits_core : ∀ (a : α) (n : nat) (l : list α) (s : stream α),
a :: nth n (inits_core l s) = nth n (inits_core (a::l) s) :=
begin
intros a n,
induction n with n' ih,
{intros, refl},
{intros l s, rw [nth_succ, inits_core_eq, tail_cons, ih, inits_core_eq (a::l) s], refl }
end
theorem nth_inits : ∀ (n : nat) (s : stream α), nth n (inits s) = approx (succ n) s :=
begin
intro n, induction n with n' ih,
{intros, refl},
{intros, rw [nth_succ, approx_succ, ← ih, tail_inits, inits_tail, cons_nth_inits_core]}
end
theorem inits_eq (s : stream α) : inits s = [head s] :: map (list.cons (head s)) (inits (tail s)) :=
begin
apply stream.ext, intro n,
cases n,
{refl},
{rw [nth_inits, nth_succ, tail_cons, nth_map, nth_inits], refl}
end
theorem zip_inits_tails (s : stream α) : zip append_stream (inits s) (tails s) = const s :=
begin
apply stream.ext, intro n,
rw [nth_zip, nth_inits, nth_tails, nth_const, approx_succ,
cons_append_stream, append_approx_drop, stream.eta]
end
def pure (a : α) : stream α :=
const a
def apply (f : stream (α → β)) (s : stream α) : stream β :=
λ n, (nth n f) (nth n s)
infix `⊛`:75 := apply -- input as \o*
theorem identity (s : stream α) : pure id ⊛ s = s := rfl
theorem composition (g : stream (β → δ)) (f : stream (α → β)) (s : stream α) : pure comp ⊛ g ⊛ f ⊛ s = g ⊛ (f ⊛ s) := rfl
theorem homomorphism (f : α → β) (a : α) : pure f ⊛ pure a = pure (f a) := rfl
theorem interchange (fs : stream (α → β)) (a : α) : fs ⊛ pure a = pure (λ f : α → β, f a) ⊛ fs := rfl
theorem map_eq_apply (f : α → β) (s : stream α) : map f s = pure f ⊛ s := rfl
def nats : stream nat :=
λ n, n
theorem nth_nats (n : nat) : nth n nats = n := rfl
theorem nats_eq : nats = 0 :: map succ nats :=
begin
apply stream.ext, intro n,
cases n, refl, rw [nth_succ], refl
end
end stream
|
416af155f10b69b9763d838850bddd62930acb74 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/group_theory/group_action/defs.lean | a11a76b7d6648999ac24e935f2bc389d1fe50fad | [
"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 | 33,842 | lean | /-
Copyright (c) 2018 Chris Hughes. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Chris Hughes, Yury Kudryashov
-/
import algebra.group.type_tags
import algebra.hom.group
import algebra.opposites
import logic.embedding
/-!
# Definitions of group actions
This file defines a hierarchy of group action type-classes on top of the previously defined
notation classes `has_smul` and its additive version `has_vadd`:
* `mul_action M α` and its additive version `add_action G P` are typeclasses used for
actions of multiplicative and additive monoids and groups; they extend notation classes
`has_smul` and `has_vadd` that are defined in `algebra.group.defs`;
* `distrib_mul_action M A` is a typeclass for an action of a multiplicative monoid on
an additive monoid such that `a • (b + c) = a • b + a • c` and `a • 0 = 0`.
The hierarchy is extended further by `module`, defined elsewhere.
Also provided are typeclasses for faithful and transitive actions, and typeclasses regarding the
interaction of different group actions,
* `smul_comm_class M N α` and its additive version `vadd_comm_class M N α`;
* `is_scalar_tower M N α` (no additive version).
* `is_central_scalar M α` (no additive version).
## Notation
- `a • b` is used as notation for `has_smul.smul a b`.
- `a +ᵥ b` is used as notation for `has_vadd.vadd a b`.
## Implementation details
This file should avoid depending on other parts of `group_theory`, to avoid import cycles.
More sophisticated lemmas belong in `group_theory.group_action`.
## Tags
group action
-/
variables {M N G A B α β γ δ : Type*}
open function (injective surjective)
/-!
### Faithful actions
-/
/-- Typeclass for faithful actions. -/
class has_faithful_vadd (G : Type*) (P : Type*) [has_vadd G P] : Prop :=
(eq_of_vadd_eq_vadd : ∀ {g₁ g₂ : G}, (∀ p : P, g₁ +ᵥ p = g₂ +ᵥ p) → g₁ = g₂)
/-- Typeclass for faithful actions. -/
@[to_additive]
class has_faithful_smul (M : Type*) (α : Type*) [has_smul M α] : Prop :=
(eq_of_smul_eq_smul : ∀ {m₁ m₂ : M}, (∀ a : α, m₁ • a = m₂ • a) → m₁ = m₂)
export has_faithful_smul (eq_of_smul_eq_smul) has_faithful_vadd (eq_of_vadd_eq_vadd)
@[to_additive]
lemma smul_left_injective' [has_smul M α] [has_faithful_smul M α] :
function.injective ((•) : M → α → α) :=
λ m₁ m₂ h, has_faithful_smul.eq_of_smul_eq_smul (congr_fun h)
/-- See also `monoid.to_mul_action` and `mul_zero_class.to_smul_with_zero`. -/
@[priority 910, -- see Note [lower instance priority]
to_additive "See also `add_monoid.to_add_action`"]
instance has_mul.to_has_smul (α : Type*) [has_mul α] : has_smul α α := ⟨(*)⟩
@[simp, to_additive] lemma smul_eq_mul (α : Type*) [has_mul α] {a a' : α} : a • a' = a * a' := rfl
/-- Type class for additive monoid actions. -/
@[ext, protect_proj] class add_action (G : Type*) (P : Type*) [add_monoid G] extends has_vadd G P :=
(zero_vadd : ∀ p : P, (0 : G) +ᵥ p = p)
(add_vadd : ∀ (g₁ g₂ : G) (p : P), (g₁ + g₂) +ᵥ p = g₁ +ᵥ (g₂ +ᵥ p))
/-- Typeclass for multiplicative actions by monoids. This generalizes group actions. -/
@[ext, protect_proj, to_additive]
class mul_action (α : Type*) (β : Type*) [monoid α] extends has_smul α β :=
(one_smul : ∀ b : β, (1 : α) • b = b)
(mul_smul : ∀ (x y : α) (b : β), (x * y) • b = x • y • b)
/-!
### (Pre)transitive action
`M` acts pretransitively on `α` if for any `x y` there is `g` such that `g • x = y` (or `g +ᵥ x = y`
for an additive action). A transitive action should furthermore have `α` nonempty.
In this section we define typeclasses `mul_action.is_pretransitive` and
`add_action.is_pretransitive` and provide `mul_action.exists_smul_eq`/`add_action.exists_vadd_eq`,
`mul_action.surjective_smul`/`add_action.surjective_vadd` as public interface to access this
property. We do not provide typeclasses `*_action.is_transitive`; users should assume
`[mul_action.is_pretransitive M α] [nonempty α]` instead. -/
/-- `M` acts pretransitively on `α` if for any `x y` there is `g` such that `g +ᵥ x = y`.
A transitive action should furthermore have `α` nonempty. -/
class add_action.is_pretransitive (M α : Type*) [has_vadd M α] : Prop :=
(exists_vadd_eq : ∀ x y : α, ∃ g : M, g +ᵥ x = y)
/-- `M` acts pretransitively on `α` if for any `x y` there is `g` such that `g • x = y`.
A transitive action should furthermore have `α` nonempty. -/
@[to_additive] class mul_action.is_pretransitive (M α : Type*) [has_smul M α] : Prop :=
(exists_smul_eq : ∀ x y : α, ∃ g : M, g • x = y)
namespace mul_action
variables (M) {α} [has_smul M α] [is_pretransitive M α]
@[to_additive] lemma exists_smul_eq (x y : α) : ∃ m : M, m • x = y :=
is_pretransitive.exists_smul_eq x y
@[to_additive] lemma surjective_smul (x : α) : surjective (λ c : M, c • x) := exists_smul_eq M x
/-- The regular action of a group on itself is transitive. -/
@[to_additive "The regular action of a group on itself is transitive."]
instance regular.is_pretransitive [group G] : is_pretransitive G G :=
⟨λ x y, ⟨y * x⁻¹, inv_mul_cancel_right _ _⟩⟩
end mul_action
/-!
### Scalar tower and commuting actions
-/
/-- A typeclass mixin saying that two additive actions on the same space commute. -/
class vadd_comm_class (M N α : Type*) [has_vadd M α] [has_vadd N α] : Prop :=
(vadd_comm : ∀ (m : M) (n : N) (a : α), m +ᵥ (n +ᵥ a) = n +ᵥ (m +ᵥ a))
/-- A typeclass mixin saying that two multiplicative actions on the same space commute. -/
@[to_additive] class smul_comm_class (M N α : Type*) [has_smul M α] [has_smul N α] : Prop :=
(smul_comm : ∀ (m : M) (n : N) (a : α), m • n • a = n • m • a)
export mul_action (mul_smul) add_action (add_vadd) smul_comm_class (smul_comm)
vadd_comm_class (vadd_comm)
/--
Frequently, we find ourselves wanting to express a bilinear map `M →ₗ[R] N →ₗ[R] P` or an
equivalence between maps `(M →ₗ[R] N) ≃ₗ[R] (M' →ₗ[R] N')` where the maps have an associated ring
`R`. Unfortunately, using definitions like these requires that `R` satisfy `comm_semiring R`, and
not just `semiring R`. Using `M →ₗ[R] N →+ P` and `(M →ₗ[R] N) ≃+ (M' →ₗ[R] N')` avoids this
problem, but throws away structure that is useful for when we _do_ have a commutative (semi)ring.
To avoid making this compromise, we instead state these definitions as `M →ₗ[R] N →ₗ[S] P` or
`(M →ₗ[R] N) ≃ₗ[S] (M' →ₗ[R] N')` and require `smul_comm_class S R` on the appropriate modules. When
the caller has `comm_semiring R`, they can set `S = R` and `smul_comm_class_self` will populate the
instance. If the caller only has `semiring R` they can still set either `R = ℕ` or `S = ℕ`, and
`add_comm_monoid.nat_smul_comm_class` or `add_comm_monoid.nat_smul_comm_class'` will populate
the typeclass, which is still sufficient to recover a `≃+` or `→+` structure.
An example of where this is used is `linear_map.prod_equiv`.
-/
library_note "bundled maps over different rings"
/-- Commutativity of actions is a symmetric relation. This lemma can't be an instance because this
would cause a loop in the instance search graph. -/
@[to_additive] lemma smul_comm_class.symm (M N α : Type*) [has_smul M α] [has_smul N α]
[smul_comm_class M N α] : smul_comm_class N M α :=
⟨λ a' a b, (smul_comm a a' b).symm⟩
/-- Commutativity of additive actions is a symmetric relation. This lemma can't be an instance
because this would cause a loop in the instance search graph. -/
add_decl_doc vadd_comm_class.symm
@[to_additive] instance smul_comm_class_self (M α : Type*) [comm_monoid M] [mul_action M α] :
smul_comm_class M M α :=
⟨λ a a' b, by rw [← mul_smul, mul_comm, mul_smul]⟩
/-- An instance of `vadd_assoc_class M N α` states that the additive action of `M` on `α` is
determined by the additive actions of `M` on `N` and `N` on `α`. -/
class vadd_assoc_class (M N α : Type*) [has_vadd M N] [has_vadd N α] [has_vadd M α] : Prop :=
(vadd_assoc : ∀ (x : M) (y : N) (z : α), (x +ᵥ y) +ᵥ z = x +ᵥ (y +ᵥ z))
/-- An instance of `is_scalar_tower M N α` states that the multiplicative
action of `M` on `α` is determined by the multiplicative actions of `M` on `N`
and `N` on `α`. -/
@[to_additive]
class is_scalar_tower (M N α : Type*) [has_smul M N] [has_smul N α] [has_smul M α] : Prop :=
(smul_assoc : ∀ (x : M) (y : N) (z : α), (x • y) • z = x • (y • z))
@[simp, to_additive] lemma smul_assoc {M N} [has_smul M N] [has_smul N α] [has_smul M α]
[is_scalar_tower M N α] (x : M) (y : N) (z : α) :
(x • y) • z = x • y • z :=
is_scalar_tower.smul_assoc x y z
@[to_additive]
instance semigroup.is_scalar_tower [semigroup α] : is_scalar_tower α α α := ⟨mul_assoc⟩
/-- A typeclass indicating that the right (aka `mul_opposite`) and left actions by `M` on `α` are
equal, that is that `M` acts centrally on `α`. This can be thought of as a version of commutativity
for `•`. -/
class is_central_scalar (M α : Type*) [has_smul M α] [has_smul Mᵐᵒᵖ α] : Prop :=
(op_smul_eq_smul : ∀ (m : M) (a : α), mul_opposite.op m • a = m • a)
lemma is_central_scalar.unop_smul_eq_smul {M α : Type*} [has_smul M α] [has_smul Mᵐᵒᵖ α]
[is_central_scalar M α] (m : Mᵐᵒᵖ) (a : α) : (mul_opposite.unop m) • a = m • a :=
mul_opposite.rec (by exact λ m, (is_central_scalar.op_smul_eq_smul _ _).symm) m
export is_central_scalar (op_smul_eq_smul unop_smul_eq_smul)
-- these instances are very low priority, as there is usually a faster way to find these instances
@[priority 50]
instance smul_comm_class.op_left [has_smul M α] [has_smul Mᵐᵒᵖ α]
[is_central_scalar M α] [has_smul N α] [smul_comm_class M N α] : smul_comm_class Mᵐᵒᵖ N α :=
⟨λ m n a, by rw [←unop_smul_eq_smul m (n • a), ←unop_smul_eq_smul m a, smul_comm]⟩
@[priority 50]
instance smul_comm_class.op_right [has_smul M α] [has_smul N α] [has_smul Nᵐᵒᵖ α]
[is_central_scalar N α] [smul_comm_class M N α] : smul_comm_class M Nᵐᵒᵖ α :=
⟨λ m n a, by rw [←unop_smul_eq_smul n (m • a), ←unop_smul_eq_smul n a, smul_comm]⟩
@[priority 50]
instance is_scalar_tower.op_left
[has_smul M α] [has_smul Mᵐᵒᵖ α] [is_central_scalar M α]
[has_smul M N] [has_smul Mᵐᵒᵖ N] [is_central_scalar M N]
[has_smul N α] [is_scalar_tower M N α] : is_scalar_tower Mᵐᵒᵖ N α :=
⟨λ m n a, by rw [←unop_smul_eq_smul m (n • a), ←unop_smul_eq_smul m n, smul_assoc]⟩
@[priority 50]
instance is_scalar_tower.op_right [has_smul M α] [has_smul M N]
[has_smul N α] [has_smul Nᵐᵒᵖ α] [is_central_scalar N α]
[is_scalar_tower M N α] : is_scalar_tower M Nᵐᵒᵖ α :=
⟨λ m n a, by rw [←unop_smul_eq_smul n a, ←unop_smul_eq_smul (m • n) a, mul_opposite.unop_smul,
smul_assoc]⟩
namespace has_smul
variables [has_smul M α]
/-- Auxiliary definition for `has_smul.comp`, `mul_action.comp_hom`,
`distrib_mul_action.comp_hom`, `module.comp_hom`, etc. -/
@[simp, to_additive /-" Auxiliary definition for `has_vadd.comp`, `add_action.comp_hom`, etc. "-/]
def comp.smul (g : N → M) (n : N) (a : α) : α :=
g n • a
variables (α)
/-- An action of `M` on `α` and a function `N → M` induces an action of `N` on `α`.
See note [reducible non-instances]. Since this is reducible, we make sure to go via
`has_smul.comp.smul` to prevent typeclass inference unfolding too far. -/
@[reducible, to_additive /-" An additive action of `M` on `α` and a function `N → M` induces
an additive action of `N` on `α` "-/]
def comp (g : N → M) : has_smul N α :=
{ smul := has_smul.comp.smul g }
variables {α}
/-- Given a tower of scalar actions `M → α → β`, if we use `has_smul.comp`
to pull back both of `M`'s actions by a map `g : N → M`, then we obtain a new
tower of scalar actions `N → α → β`.
This cannot be an instance because it can cause infinite loops whenever the `has_smul` arguments
are still metavariables.
-/
@[priority 100, to_additive "Given a tower of additive actions `M → α → β`, if we use
`has_smul.comp` to pull back both of `M`'s actions by a map `g : N → M`, then we obtain a new tower
of scalar actions `N → α → β`.
This cannot be an instance because it can cause infinite loops whenever the `has_smul` arguments
are still metavariables."]
lemma comp.is_scalar_tower [has_smul M β] [has_smul α β] [is_scalar_tower M α β] (g : N → M) :
(by haveI := comp α g; haveI := comp β g; exact is_scalar_tower N α β) :=
by exact {smul_assoc := λ n, @smul_assoc _ _ _ _ _ _ _ (g n) }
/--
This cannot be an instance because it can cause infinite loops whenever the `has_smul` arguments
are still metavariables.
-/
@[priority 100]
lemma comp.smul_comm_class [has_smul β α] [smul_comm_class M β α] (g : N → M) :
(by haveI := comp α g; exact smul_comm_class N β α) :=
by exact {smul_comm := λ n, @smul_comm _ _ _ _ _ _ (g n) }
/--
This cannot be an instance because it can cause infinite loops whenever the `has_smul` arguments
are still metavariables.
-/
@[priority 100]
lemma comp.smul_comm_class' [has_smul β α] [smul_comm_class β M α] (g : N → M) :
(by haveI := comp α g; exact smul_comm_class β N α) :=
by exact {smul_comm := λ _ n, @smul_comm _ _ _ _ _ _ _ (g n) }
end has_smul
section
/-- Note that the `smul_comm_class α β β` typeclass argument is usually satisfied by `algebra α β`.
-/
@[to_additive, nolint to_additive_doc]
lemma mul_smul_comm [has_mul β] [has_smul α β] [smul_comm_class α β β] (s : α) (x y : β) :
x * (s • y) = s • (x * y) :=
(smul_comm s x y).symm
/-- Note that the `is_scalar_tower α β β` typeclass argument is usually satisfied by `algebra α β`.
-/
@[to_additive, nolint to_additive_doc]
lemma smul_mul_assoc [has_mul β] [has_smul α β] [is_scalar_tower α β β] (r : α) (x y : β) :
(r • x) * y = r • (x * y) :=
smul_assoc r x y
@[to_additive]
lemma smul_smul_smul_comm [has_smul α β] [has_smul α γ] [has_smul β δ] [has_smul α δ]
[has_smul γ δ] [is_scalar_tower α β δ] [is_scalar_tower α γ δ] [smul_comm_class β γ δ]
(a : α) (b : β) (c : γ) (d : δ) : (a • b) • (c • d) = (a • c) • b • d :=
by { rw [smul_assoc, smul_assoc, smul_comm b], apply_instance }
variables [has_smul M α]
@[to_additive]
lemma commute.smul_right [has_mul α] [smul_comm_class M α α] [is_scalar_tower M α α]
{a b : α} (h : commute a b) (r : M) :
commute a (r • b) :=
(mul_smul_comm _ _ _).trans ((congr_arg _ h).trans $ (smul_mul_assoc _ _ _).symm)
@[to_additive]
lemma commute.smul_left [has_mul α] [smul_comm_class M α α] [is_scalar_tower M α α]
{a b : α} (h : commute a b) (r : M) :
commute (r • a) b :=
(h.symm.smul_right r).symm
end
section ite
variables [has_smul M α] (p : Prop) [decidable p]
@[to_additive] lemma ite_smul (a₁ a₂ : M) (b : α) : (ite p a₁ a₂) • b = ite p (a₁ • b) (a₂ • b) :=
by split_ifs; refl
@[to_additive] lemma smul_ite (a : M) (b₁ b₂ : α) : a • (ite p b₁ b₂) = ite p (a • b₁) (a • b₂) :=
by split_ifs; refl
end ite
section
variables [monoid M] [mul_action M α]
@[to_additive] lemma smul_smul (a₁ a₂ : M) (b : α) : a₁ • a₂ • b = (a₁ * a₂) • b :=
(mul_smul _ _ _).symm
variable (M)
@[simp, to_additive] theorem one_smul (b : α) : (1 : M) • b = b := mul_action.one_smul _
/-- `has_smul` version of `one_mul_eq_id` -/
@[to_additive "`has_vadd` version of `zero_add_eq_id`"]
lemma one_smul_eq_id : ((•) (1 : M) : α → α) = id := funext $ one_smul _
/-- `has_smul` version of `comp_mul_left` -/
@[to_additive "`has_vadd` version of `comp_add_left`"]
lemma comp_smul_left (a₁ a₂ : M) : (•) a₁ ∘ (•) a₂ = ((•) (a₁ * a₂) : α → α) :=
funext $ λ _, (mul_smul _ _ _).symm
variables {M}
/-- Pullback a multiplicative action along an injective map respecting `•`.
See note [reducible non-instances]. -/
@[reducible, to_additive "Pullback an additive action along an injective map respecting `+ᵥ`."]
protected def function.injective.mul_action [has_smul M β] (f : β → α)
(hf : injective f) (smul : ∀ (c : M) x, f (c • x) = c • f x) :
mul_action M β :=
{ smul := (•),
one_smul := λ x, hf $ (smul _ _).trans $ one_smul _ (f x),
mul_smul := λ c₁ c₂ x, hf $ by simp only [smul, mul_smul] }
/-- Pushforward a multiplicative action along a surjective map respecting `•`.
See note [reducible non-instances]. -/
@[reducible, to_additive "Pushforward an additive action along a surjective map respecting `+ᵥ`."]
protected def function.surjective.mul_action [has_smul M β] (f : α → β) (hf : surjective f)
(smul : ∀ (c : M) x, f (c • x) = c • f x) :
mul_action M β :=
{ smul := (•),
one_smul := λ y, by { rcases hf y with ⟨x, rfl⟩, rw [← smul, one_smul] },
mul_smul := λ c₁ c₂ y, by { rcases hf y with ⟨x, rfl⟩, simp only [← smul, mul_smul] } }
/-- Push forward the action of `R` on `M` along a compatible surjective map `f : R →* S`.
See also `function.surjective.distrib_mul_action_left` and `function.surjective.module_left`.
-/
@[reducible, to_additive "Push forward the action of `R` on `M` along a compatible
surjective map `f : R →+ S`."]
def function.surjective.mul_action_left {R S M : Type*} [monoid R] [mul_action R M]
[monoid S] [has_smul S M]
(f : R →* S) (hf : function.surjective f) (hsmul : ∀ c (x : M), f c • x = c • x) :
mul_action S M :=
{ smul := (•),
one_smul := λ b, by rw [← f.map_one, hsmul, one_smul],
mul_smul := hf.forall₂.mpr $ λ a b x, by simp only [← f.map_mul, hsmul, mul_smul] }
section
variables (M)
/-- The regular action of a monoid on itself by left multiplication.
This is promoted to a module by `semiring.to_module`. -/
@[priority 910, to_additive] -- see Note [lower instance priority]
instance monoid.to_mul_action : mul_action M M :=
{ smul := (*),
one_smul := one_mul,
mul_smul := mul_assoc }
/-- The regular action of a monoid on itself by left addition.
This is promoted to an `add_torsor` by `add_group_is_add_torsor`. -/
add_decl_doc add_monoid.to_add_action
@[to_additive] instance is_scalar_tower.left : is_scalar_tower M M α :=
⟨λ x y z, mul_smul x y z⟩
variables {M}
/-- Note that the `is_scalar_tower M α α` and `smul_comm_class M α α` typeclass arguments are
usually satisfied by `algebra M α`. -/
@[to_additive, nolint to_additive_doc]
lemma smul_mul_smul [has_mul α] (r s : M) (x y : α)
[is_scalar_tower M α α] [smul_comm_class M α α] :
(r • x) * (s • y) = (r * s) • (x * y) :=
by rw [smul_mul_assoc, mul_smul_comm, ← smul_assoc, smul_eq_mul]
end
namespace mul_action
variables (M α)
/-- Embedding of `α` into functions `M → α` induced by a multiplicative action of `M` on `α`. -/
@[to_additive] def to_fun : α ↪ (M → α) :=
⟨λ y x, x • y, λ y₁ y₂ H, one_smul M y₁ ▸ one_smul M y₂ ▸ by convert congr_fun H 1⟩
/-- Embedding of `α` into functions `M → α` induced by an additive action of `M` on `α`. -/
add_decl_doc add_action.to_fun
variables {M α}
@[simp, to_additive] lemma to_fun_apply (x : M) (y : α) : mul_action.to_fun M α y x = x • y :=
rfl
variable (α)
/-- A multiplicative action of `M` on `α` and a monoid homomorphism `N → M` induce
a multiplicative action of `N` on `α`.
See note [reducible non-instances]. -/
@[reducible, to_additive] def comp_hom [monoid N] (g : N →* M) :
mul_action N α :=
{ smul := has_smul.comp.smul g,
one_smul := by simp [g.map_one, mul_action.one_smul],
mul_smul := by simp [g.map_mul, mul_action.mul_smul] }
/-- An additive action of `M` on `α` and an additive monoid homomorphism `N → M` induce
an additive action of `N` on `α`.
See note [reducible non-instances]. -/
add_decl_doc add_action.comp_hom
end mul_action
end
section compatible_scalar
@[simp, to_additive] lemma smul_one_smul {M} (N) [monoid N] [has_smul M N] [mul_action N α]
[has_smul M α] [is_scalar_tower M N α] (x : M) (y : α) :
(x • (1 : N)) • y = x • y :=
by rw [smul_assoc, one_smul]
@[simp, to_additive] lemma smul_one_mul {M N} [mul_one_class N] [has_smul M N]
[is_scalar_tower M N N] (x : M) (y : N) : (x • 1) * y = x • y :=
by rw [smul_mul_assoc, one_mul]
@[simp, to_additive] lemma mul_smul_one
{M N} [mul_one_class N] [has_smul M N] [smul_comm_class M N N] (x : M) (y : N) :
y * (x • 1) = x • y :=
by rw [← smul_eq_mul, ← smul_comm, smul_eq_mul, mul_one]
@[to_additive]
lemma is_scalar_tower.of_smul_one_mul {M N} [monoid N] [has_smul M N]
(h : ∀ (x : M) (y : N), (x • (1 : N)) * y = x • y) :
is_scalar_tower M N N :=
⟨λ x y z, by rw [← h, smul_eq_mul, mul_assoc, h, smul_eq_mul]⟩
@[to_additive] lemma smul_comm_class.of_mul_smul_one {M N} [monoid N] [has_smul M N]
(H : ∀ (x : M) (y : N), y * (x • (1 : N)) = x • y) : smul_comm_class M N N :=
⟨λ x y z, by rw [← H x z, smul_eq_mul, ← H, smul_eq_mul, mul_assoc]⟩
end compatible_scalar
/-- Typeclass for multiplicative actions on additive structures. This generalizes group modules. -/
@[ext] class distrib_mul_action (M : Type*) (A : Type*) [monoid M] [add_monoid A]
extends mul_action M A :=
(smul_add : ∀(r : M) (x y : A), r • (x + y) = r • x + r • y)
(smul_zero : ∀(r : M), r • (0 : A) = 0)
section
variables [monoid M] [add_monoid A] [distrib_mul_action M A]
theorem smul_add (a : M) (b₁ b₂ : A) : a • (b₁ + b₂) = a • b₁ + a • b₂ :=
distrib_mul_action.smul_add _ _ _
@[simp] theorem smul_zero (a : M) : a • (0 : A) = 0 :=
distrib_mul_action.smul_zero _
/-- Pullback a distributive multiplicative action along an injective additive monoid
homomorphism.
See note [reducible non-instances]. -/
@[reducible]
protected def function.injective.distrib_mul_action [add_monoid B] [has_smul M B] (f : B →+ A)
(hf : injective f) (smul : ∀ (c : M) x, f (c • x) = c • f x) :
distrib_mul_action M B :=
{ smul := (•),
smul_add := λ c x y, hf $ by simp only [smul, f.map_add, smul_add],
smul_zero := λ c, hf $ by simp only [smul, f.map_zero, smul_zero],
.. hf.mul_action f smul }
/-- Pushforward a distributive multiplicative action along a surjective additive monoid
homomorphism.
See note [reducible non-instances]. -/
@[reducible]
protected def function.surjective.distrib_mul_action [add_monoid B] [has_smul M B] (f : A →+ B)
(hf : surjective f) (smul : ∀ (c : M) x, f (c • x) = c • f x) :
distrib_mul_action M B :=
{ smul := (•),
smul_add := λ c x y, by { rcases hf x with ⟨x, rfl⟩, rcases hf y with ⟨y, rfl⟩,
simp only [smul_add, ← smul, ← f.map_add] },
smul_zero := λ c, by simp only [← f.map_zero, ← smul, smul_zero],
.. hf.mul_action f smul }
/-- Push forward the action of `R` on `M` along a compatible surjective map `f : R →* S`.
See also `function.surjective.mul_action_left` and `function.surjective.module_left`.
-/
@[reducible]
def function.surjective.distrib_mul_action_left {R S M : Type*} [monoid R] [add_monoid M]
[distrib_mul_action R M] [monoid S] [has_smul S M]
(f : R →* S) (hf : function.surjective f) (hsmul : ∀ c (x : M), f c • x = c • x) :
distrib_mul_action S M :=
{ smul := (•),
smul_zero := hf.forall.mpr $ λ c, by rw [hsmul, smul_zero],
smul_add := hf.forall.mpr $ λ c x y, by simp only [hsmul, smul_add],
.. hf.mul_action_left f hsmul }
variable (A)
/-- Compose a `distrib_mul_action` with a `monoid_hom`, with action `f r' • m`.
See note [reducible non-instances]. -/
@[reducible] def distrib_mul_action.comp_hom [monoid N] (f : N →* M) :
distrib_mul_action N A :=
{ smul := has_smul.comp.smul f,
smul_zero := λ x, smul_zero (f x),
smul_add := λ x, smul_add (f x),
.. mul_action.comp_hom A f }
/-- Each element of the monoid defines a additive monoid homomorphism. -/
@[simps]
def distrib_mul_action.to_add_monoid_hom (x : M) : A →+ A :=
{ to_fun := (•) x,
map_zero' := smul_zero x,
map_add' := smul_add x }
variables (M)
/-- Each element of the monoid defines an additive monoid homomorphism. -/
@[simps]
def distrib_mul_action.to_add_monoid_End : M →* add_monoid.End A :=
{ to_fun := distrib_mul_action.to_add_monoid_hom A,
map_one' := add_monoid_hom.ext $ one_smul M,
map_mul' := λ x y, add_monoid_hom.ext $ mul_smul x y }
instance add_monoid.nat_smul_comm_class : smul_comm_class ℕ M A :=
{ smul_comm := λ n x y, ((distrib_mul_action.to_add_monoid_hom A x).map_nsmul y n).symm }
-- `smul_comm_class.symm` is not registered as an instance, as it would cause a loop
instance add_monoid.nat_smul_comm_class' : smul_comm_class M ℕ A :=
smul_comm_class.symm _ _ _
end
section
variables [monoid M] [add_group A] [distrib_mul_action M A]
instance add_group.int_smul_comm_class : smul_comm_class ℤ M A :=
{ smul_comm := λ n x y, ((distrib_mul_action.to_add_monoid_hom A x).map_zsmul y n).symm }
-- `smul_comm_class.symm` is not registered as an instance, as it would cause a loop
instance add_group.int_smul_comm_class' : smul_comm_class M ℤ A :=
smul_comm_class.symm _ _ _
@[simp] theorem smul_neg (r : M) (x : A) : r • (-x) = -(r • x) :=
eq_neg_of_add_eq_zero_left $ by rw [← smul_add, neg_add_self, smul_zero]
theorem smul_sub (r : M) (x y : A) : r • (x - y) = r • x - r • y :=
by rw [sub_eq_add_neg, sub_eq_add_neg, smul_add, smul_neg]
end
/-- Typeclass for multiplicative actions on multiplicative structures. This generalizes
conjugation actions. -/
@[ext] class mul_distrib_mul_action (M : Type*) (A : Type*) [monoid M] [monoid A]
extends mul_action M A :=
(smul_mul : ∀ (r : M) (x y : A), r • (x * y) = (r • x) * (r • y))
(smul_one : ∀ (r : M), r • (1 : A) = 1)
export mul_distrib_mul_action (smul_one)
section
variables [monoid M] [monoid A] [mul_distrib_mul_action M A]
theorem smul_mul' (a : M) (b₁ b₂ : A) : a • (b₁ * b₂) = (a • b₁) * (a • b₂) :=
mul_distrib_mul_action.smul_mul _ _ _
/-- Pullback a multiplicative distributive multiplicative action along an injective monoid
homomorphism.
See note [reducible non-instances]. -/
@[reducible]
protected def function.injective.mul_distrib_mul_action [monoid B] [has_smul M B] (f : B →* A)
(hf : injective f) (smul : ∀ (c : M) x, f (c • x) = c • f x) :
mul_distrib_mul_action M B :=
{ smul := (•),
smul_mul := λ c x y, hf $ by simp only [smul, f.map_mul, smul_mul'],
smul_one := λ c, hf $ by simp only [smul, f.map_one, smul_one],
.. hf.mul_action f smul }
/-- Pushforward a multiplicative distributive multiplicative action along a surjective monoid
homomorphism.
See note [reducible non-instances]. -/
@[reducible]
protected def function.surjective.mul_distrib_mul_action [monoid B] [has_smul M B] (f : A →* B)
(hf : surjective f) (smul : ∀ (c : M) x, f (c • x) = c • f x) :
mul_distrib_mul_action M B :=
{ smul := (•),
smul_mul := λ c x y, by { rcases hf x with ⟨x, rfl⟩, rcases hf y with ⟨y, rfl⟩,
simp only [smul_mul', ← smul, ← f.map_mul] },
smul_one := λ c, by simp only [← f.map_one, ← smul, smul_one],
.. hf.mul_action f smul }
variable (A)
/-- Compose a `mul_distrib_mul_action` with a `monoid_hom`, with action `f r' • m`.
See note [reducible non-instances]. -/
@[reducible] def mul_distrib_mul_action.comp_hom [monoid N] (f : N →* M) :
mul_distrib_mul_action N A :=
{ smul := has_smul.comp.smul f,
smul_one := λ x, smul_one (f x),
smul_mul := λ x, smul_mul' (f x),
.. mul_action.comp_hom A f }
/-- Scalar multiplication by `r` as a `monoid_hom`. -/
def mul_distrib_mul_action.to_monoid_hom (r : M) : A →* A :=
{ to_fun := (•) r,
map_one' := smul_one r,
map_mul' := smul_mul' r }
variable {A}
@[simp] lemma mul_distrib_mul_action.to_monoid_hom_apply (r : M) (x : A) :
mul_distrib_mul_action.to_monoid_hom A r x = r • x := rfl
variables (M A)
/-- Each element of the monoid defines a monoid homomorphism. -/
@[simps]
def mul_distrib_mul_action.to_monoid_End : M →* monoid.End A :=
{ to_fun := mul_distrib_mul_action.to_monoid_hom A,
map_one' := monoid_hom.ext $ one_smul M,
map_mul' := λ x y, monoid_hom.ext $ mul_smul x y }
end
section
variables [monoid M] [group A] [mul_distrib_mul_action M A]
@[simp] theorem smul_inv' (r : M) (x : A) : r • (x⁻¹) = (r • x)⁻¹ :=
(mul_distrib_mul_action.to_monoid_hom A r).map_inv x
theorem smul_div' (r : M) (x y : A) : r • (x / y) = (r • x) / (r • y) :=
map_div (mul_distrib_mul_action.to_monoid_hom A r) x y
end
variable (α)
/-- The monoid of endomorphisms.
Note that this is generalized by `category_theory.End` to categories other than `Type u`. -/
protected def function.End := α → α
instance : monoid (function.End α) :=
{ one := id,
mul := (∘),
mul_assoc := λ f g h, rfl,
mul_one := λ f, rfl,
one_mul := λ f, rfl, }
instance : inhabited (function.End α) := ⟨1⟩
variable {α}
/-- The tautological action by `function.End α` on `α`.
This is generalized to bundled endomorphisms by:
* `equiv.perm.apply_mul_action`
* `add_monoid.End.apply_distrib_mul_action`
* `add_aut.apply_distrib_mul_action`
* `mul_aut.apply_mul_distrib_mul_action`
* `ring_hom.apply_distrib_mul_action`
* `linear_equiv.apply_distrib_mul_action`
* `linear_map.apply_module`
* `ring_hom.apply_mul_semiring_action`
* `alg_equiv.apply_mul_semiring_action`
-/
instance function.End.apply_mul_action : mul_action (function.End α) α :=
{ smul := ($),
one_smul := λ _, rfl,
mul_smul := λ _ _ _, rfl }
@[simp] lemma function.End.smul_def (f : function.End α) (a : α) : f • a = f a := rfl
/-- `function.End.apply_mul_action` is faithful. -/
instance function.End.apply_has_faithful_smul : has_faithful_smul (function.End α) α :=
⟨λ x y, funext⟩
/-- The tautological action by `add_monoid.End α` on `α`.
This generalizes `function.End.apply_mul_action`. -/
instance add_monoid.End.apply_distrib_mul_action [add_monoid α] :
distrib_mul_action (add_monoid.End α) α :=
{ smul := ($),
smul_zero := add_monoid_hom.map_zero,
smul_add := add_monoid_hom.map_add,
one_smul := λ _, rfl,
mul_smul := λ _ _ _, rfl }
@[simp] lemma add_monoid.End.smul_def [add_monoid α] (f : add_monoid.End α) (a : α) :
f • a = f a := rfl
/-- `add_monoid.End.apply_distrib_mul_action` is faithful. -/
instance add_monoid.End.apply_has_faithful_smul [add_monoid α] :
has_faithful_smul (add_monoid.End α) α :=
⟨add_monoid_hom.ext⟩
/-- The monoid hom representing a monoid action.
When `M` is a group, see `mul_action.to_perm_hom`. -/
def mul_action.to_End_hom [monoid M] [mul_action M α] : M →* function.End α :=
{ to_fun := (•),
map_one' := funext (one_smul M),
map_mul' := λ x y, funext (mul_smul x y) }
/-- The monoid action induced by a monoid hom to `function.End α`
See note [reducible non-instances]. -/
@[reducible]
def mul_action.of_End_hom [monoid M] (f : M →* function.End α) : mul_action M α :=
mul_action.comp_hom α f
/-- The tautological additive action by `additive (function.End α)` on `α`. -/
instance add_action.function_End : add_action (additive (function.End α)) α :=
{ vadd := ($),
zero_vadd := λ _, rfl,
add_vadd := λ _ _ _, rfl }
/-- The additive monoid hom representing an additive monoid action.
When `M` is a group, see `add_action.to_perm_hom`. -/
def add_action.to_End_hom [add_monoid M] [add_action M α] : M →+ additive (function.End α) :=
{ to_fun := (+ᵥ),
map_zero' := funext (zero_vadd M),
map_add' := λ x y, funext (add_vadd x y) }
/-- The additive action induced by a hom to `additive (function.End α)`
See note [reducible non-instances]. -/
@[reducible]
def add_action.of_End_hom [add_monoid M] (f : M →+ additive (function.End α)) : add_action M α :=
add_action.comp_hom α f
/-! ### `additive`, `multiplicative` -/
section
open additive multiplicative
instance additive.has_vadd [has_smul α β] : has_vadd (additive α) β := ⟨λ a, (•) (to_mul a)⟩
instance multiplicative.has_smul [has_vadd α β] : has_smul (multiplicative α) β :=
⟨λ a, (+ᵥ) (to_add a)⟩
@[simp] lemma to_mul_smul [has_smul α β] (a) (b : β) : (to_mul a : α) • b = a +ᵥ b := rfl
@[simp] lemma of_mul_vadd [has_smul α β] (a : α) (b : β) : of_mul a +ᵥ b = a • b := rfl
@[simp] lemma to_add_vadd [has_vadd α β] (a) (b : β) : (to_add a : α) +ᵥ b = a • b := rfl
@[simp] lemma of_add_smul [has_vadd α β] (a : α) (b : β) : of_add a • b = a +ᵥ b := rfl
instance additive.add_action [monoid α] [mul_action α β] : add_action (additive α) β :=
{ zero_vadd := mul_action.one_smul,
add_vadd := mul_action.mul_smul }
instance multiplicative.mul_action [add_monoid α] [add_action α β] :
mul_action (multiplicative α) β :=
{ one_smul := add_action.zero_vadd,
mul_smul := add_action.add_vadd }
instance additive.add_action_is_pretransitive [monoid α] [mul_action α β]
[mul_action.is_pretransitive α β] : add_action.is_pretransitive (additive α) β :=
⟨@mul_action.exists_smul_eq α _ _ _⟩
instance multiplicative.add_action_is_pretransitive [add_monoid α] [add_action α β]
[add_action.is_pretransitive α β] : mul_action.is_pretransitive (multiplicative α) β :=
⟨@add_action.exists_vadd_eq α _ _ _⟩
instance additive.vadd_comm_class [has_smul α γ] [has_smul β γ] [smul_comm_class α β γ] :
vadd_comm_class (additive α) (additive β) γ :=
⟨@smul_comm α β _ _ _ _⟩
instance multiplicative.smul_comm_class [has_vadd α γ] [has_vadd β γ] [vadd_comm_class α β γ] :
smul_comm_class (multiplicative α) (multiplicative β) γ :=
⟨@vadd_comm α β _ _ _ _⟩
end
|
8271076700effb7382dcf9fc068050c6644eb62b | 4950bf76e5ae40ba9f8491647d0b6f228ddce173 | /src/algebra/opposites.lean | 8f63e89ceaeb912159d7c230e9686f20722caac5 | [
"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 | 8,661 | 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 data.opposite
import algebra.field
import group_theory.group_action.defs
import data.equiv.mul_add
/-!
# Algebraic operations on `αᵒᵖ`
-/
namespace opposite
universes u
variables (α : Type u)
instance [has_add α] : has_add (opposite α) :=
{ add := λ x y, op (unop x + unop y) }
instance [add_semigroup α] : add_semigroup (opposite α) :=
{ add_assoc := λ x y z, unop_injective $ add_assoc (unop x) (unop y) (unop z),
.. opposite.has_add α }
instance [add_left_cancel_semigroup α] : add_left_cancel_semigroup (opposite α) :=
{ add_left_cancel := λ x y z H, unop_injective $ add_left_cancel $ op_injective H,
.. opposite.add_semigroup α }
instance [add_right_cancel_semigroup α] : add_right_cancel_semigroup (opposite α) :=
{ add_right_cancel := λ x y z H, unop_injective $ add_right_cancel $ op_injective H,
.. opposite.add_semigroup α }
instance [add_comm_semigroup α] : add_comm_semigroup (opposite α) :=
{ add_comm := λ x y, unop_injective $ add_comm (unop x) (unop y),
.. opposite.add_semigroup α }
instance [has_zero α] : has_zero (opposite α) :=
{ zero := op 0 }
instance [nontrivial α] : nontrivial (opposite α) :=
let ⟨x, y, h⟩ := exists_pair_ne α in nontrivial_of_ne (op x) (op y) (op_injective.ne h)
section
local attribute [reducible] opposite
@[simp] lemma unop_eq_zero_iff [has_zero α] (a : αᵒᵖ) : a.unop = (0 : α) ↔ a = (0 : αᵒᵖ) :=
iff.refl _
@[simp] lemma op_eq_zero_iff [has_zero α] (a : α) : op a = (0 : αᵒᵖ) ↔ a = (0 : α) :=
iff.refl _
end
instance [add_monoid α] : add_monoid (opposite α) :=
{ zero_add := λ x, unop_injective $ zero_add $ unop x,
add_zero := λ x, unop_injective $ add_zero $ unop x,
.. opposite.add_semigroup α, .. opposite.has_zero α }
instance [add_comm_monoid α] : add_comm_monoid (opposite α) :=
{ .. opposite.add_monoid α, .. opposite.add_comm_semigroup α }
instance [has_neg α] : has_neg (opposite α) :=
{ neg := λ x, op $ -(unop x) }
instance [add_group α] : add_group (opposite α) :=
{ add_left_neg := λ x, unop_injective $ add_left_neg $ unop x,
.. opposite.add_monoid α, .. opposite.has_neg α }
instance [add_comm_group α] : add_comm_group (opposite α) :=
{ .. opposite.add_group α, .. opposite.add_comm_monoid α }
instance [has_mul α] : has_mul (opposite α) :=
{ mul := λ x y, op (unop y * unop x) }
instance [semigroup α] : semigroup (opposite α) :=
{ mul_assoc := λ x y z, unop_injective $ eq.symm $ mul_assoc (unop z) (unop y) (unop x),
.. opposite.has_mul α }
instance [right_cancel_semigroup α] : left_cancel_semigroup (opposite α) :=
{ mul_left_cancel := λ x y z H, unop_injective $ mul_right_cancel $ op_injective H,
.. opposite.semigroup α }
instance [left_cancel_semigroup α] : right_cancel_semigroup (opposite α) :=
{ mul_right_cancel := λ x y z H, unop_injective $ mul_left_cancel $ op_injective H,
.. opposite.semigroup α }
instance [comm_semigroup α] : comm_semigroup (opposite α) :=
{ mul_comm := λ x y, unop_injective $ mul_comm (unop y) (unop x),
.. opposite.semigroup α }
instance [has_one α] : has_one (opposite α) :=
{ one := op 1 }
section
local attribute [reducible] opposite
@[simp] lemma unop_eq_one_iff [has_one α] (a : αᵒᵖ) : a.unop = 1 ↔ a = 1 :=
iff.refl _
@[simp] lemma op_eq_one_iff [has_one α] (a : α) : op a = 1 ↔ a = 1 :=
iff.refl _
end
instance [monoid α] : monoid (opposite α) :=
{ one_mul := λ x, unop_injective $ mul_one $ unop x,
mul_one := λ x, unop_injective $ one_mul $ unop x,
.. opposite.semigroup α, .. opposite.has_one α }
instance [comm_monoid α] : comm_monoid (opposite α) :=
{ .. opposite.monoid α, .. opposite.comm_semigroup α }
instance [has_inv α] : has_inv (opposite α) :=
{ inv := λ x, op $ (unop x)⁻¹ }
instance [group α] : group (opposite α) :=
{ mul_left_inv := λ x, unop_injective $ mul_inv_self $ unop x,
.. opposite.monoid α, .. opposite.has_inv α }
instance [comm_group α] : comm_group (opposite α) :=
{ .. opposite.group α, .. opposite.comm_monoid α }
instance [distrib α] : distrib (opposite α) :=
{ left_distrib := λ x y z, unop_injective $ add_mul (unop y) (unop z) (unop x),
right_distrib := λ x y z, unop_injective $ mul_add (unop z) (unop x) (unop y),
.. opposite.has_add α, .. opposite.has_mul α }
instance [semiring α] : semiring (opposite α) :=
{ zero_mul := λ x, unop_injective $ mul_zero $ unop x,
mul_zero := λ x, unop_injective $ zero_mul $ unop x,
.. opposite.add_comm_monoid α, .. opposite.monoid α, .. opposite.distrib α }
instance [ring α] : ring (opposite α) :=
{ .. opposite.add_comm_group α, .. opposite.monoid α, .. opposite.semiring α }
instance [comm_ring α] : comm_ring (opposite α) :=
{ .. opposite.ring α, .. opposite.comm_semigroup α }
instance [integral_domain α] : integral_domain (opposite α) :=
{ eq_zero_or_eq_zero_of_mul_eq_zero := λ x y (H : op (_ * _) = op (0:α)),
or.cases_on (eq_zero_or_eq_zero_of_mul_eq_zero $ op_injective H)
(λ hy, or.inr $ unop_injective $ hy) (λ hx, or.inl $ unop_injective $ hx),
.. opposite.comm_ring α, .. opposite.nontrivial α }
instance [field α] : field (opposite α) :=
{ mul_inv_cancel := λ x hx, unop_injective $ inv_mul_cancel $ λ hx', hx $ unop_injective hx',
inv_zero := unop_injective inv_zero,
.. opposite.comm_ring α, .. opposite.has_inv α, .. opposite.nontrivial α }
instance (R : Type*) [has_scalar R α] : has_scalar R (opposite α) :=
{ smul := λ c x, op (c • unop x) }
instance (R : Type*) [monoid R] [mul_action R α] : mul_action R (opposite α) :=
{ one_smul := λ x, unop_injective $ one_smul R (unop x),
mul_smul := λ r₁ r₂ x, unop_injective $ mul_smul r₁ r₂ (unop x),
..opposite.has_scalar α R }
instance (R : Type*) [monoid R] [add_monoid α] [distrib_mul_action R α] :
distrib_mul_action R (opposite α) :=
{ smul_add := λ r x₁ x₂, unop_injective $ smul_add r (unop x₁) (unop x₂),
smul_zero := λ r, unop_injective $ smul_zero r,
..opposite.mul_action α R }
@[simp] lemma op_zero [has_zero α] : op (0 : α) = 0 := rfl
@[simp] lemma unop_zero [has_zero α] : unop (0 : αᵒᵖ) = 0 := rfl
@[simp] lemma op_one [has_one α] : op (1 : α) = 1 := rfl
@[simp] lemma unop_one [has_one α] : unop (1 : αᵒᵖ) = 1 := rfl
variable {α}
@[simp] lemma op_add [has_add α] (x y : α) : op (x + y) = op x + op y := rfl
@[simp] lemma unop_add [has_add α] (x y : αᵒᵖ) : unop (x + y) = unop x + unop y := rfl
@[simp] lemma op_neg [has_neg α] (x : α) : op (-x) = -op x := rfl
@[simp] lemma unop_neg [has_neg α] (x : αᵒᵖ) : unop (-x) = -unop x := rfl
@[simp] lemma op_mul [has_mul α] (x y : α) : op (x * y) = op y * op x := rfl
@[simp] lemma unop_mul [has_mul α] (x y : αᵒᵖ) : unop (x * y) = unop y * unop x := rfl
@[simp] lemma op_inv [has_inv α] (x : α) : op (x⁻¹) = (op x)⁻¹ := rfl
@[simp] lemma unop_inv [has_inv α] (x : αᵒᵖ) : unop (x⁻¹) = (unop x)⁻¹ := rfl
@[simp] lemma op_sub [add_group α] (x y : α) : op (x - y) = op x - op y := rfl
@[simp] lemma unop_sub [add_group α] (x y : αᵒᵖ) : unop (x - y) = unop x - unop y := rfl
@[simp] lemma op_smul {R : Type*} [has_scalar R α] (c : R) (a : α) : op (c • a) = c • op a := rfl
@[simp] lemma unop_smul {R : Type*} [has_scalar R α] (c : R) (a : αᵒᵖ) :
unop (c • a) = c • unop a := rfl
/-- The function `op` is an additive equivalence. -/
def op_add_equiv [has_add α] : α ≃+ αᵒᵖ :=
{ map_add' := λ a b, rfl, .. equiv_to_opposite }
@[simp] lemma coe_op_add_equiv [has_add α] : (op_add_equiv : α → αᵒᵖ) = op := rfl
@[simp] lemma coe_op_add_equiv_symm [has_add α] :
(op_add_equiv.symm : αᵒᵖ → α) = unop := rfl
@[simp] lemma op_add_equiv_to_equiv [has_add α] :
(op_add_equiv : α ≃+ αᵒᵖ).to_equiv = equiv_to_opposite :=
rfl
end opposite
open opposite
/-- A ring homomorphism `f : R →+* S` such that `f x` commutes with `f y` for all `x, y` defines
a ring homomorphism to `Sᵒᵖ`. -/
def ring_hom.to_opposite {R S : Type*} [semiring R] [semiring S] (f : R →+* S)
(hf : ∀ x y, commute (f x) (f y)) : R →+* Sᵒᵖ :=
{ map_one' := congr_arg op f.map_one,
map_mul' := λ x y, by simp [(hf x y).eq],
.. (opposite.op_add_equiv : S ≃+ Sᵒᵖ).to_add_monoid_hom.comp ↑f }
@[simp] lemma ring_hom.coe_to_opposite {R S : Type*} [semiring R] [semiring S] (f : R →+* S)
(hf : ∀ x y, commute (f x) (f y)) : ⇑(f.to_opposite hf) = op ∘ f := rfl
|
75ddec6eb6bc18baecd332b6253933fb19fee600 | 80cc5bf14c8ea85ff340d1d747a127dcadeb966f | /src/data/vector2.lean | 52dd6f0a79fd1e445c12067aadaab5e9f85e6ee0 | [
"Apache-2.0"
] | permissive | lacker/mathlib | f2439c743c4f8eb413ec589430c82d0f73b2d539 | ddf7563ac69d42cfa4a1bfe41db1fed521bd795f | refs/heads/master | 1,671,948,326,773 | 1,601,479,268,000 | 1,601,479,268,000 | 298,686,743 | 0 | 0 | Apache-2.0 | 1,601,070,794,000 | 1,601,070,794,000 | null | UTF-8 | Lean | false | false | 10,894 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
Additional theorems about the `vector` type.
-/
import data.vector
import data.list.nodup
import data.list.of_fn
import control.applicative
universes u
variables {n : ℕ}
namespace vector
variables {α : Type*}
attribute [simp] head_cons tail_cons
instance [inhabited α] : inhabited (vector α n) :=
⟨of_fn (λ _, default α)⟩
theorem to_list_injective : function.injective (@to_list α n) :=
subtype.val_injective
@[simp] theorem cons_val (a : α) : ∀ (v : vector α n), (a :: v).val = a :: v.val
| ⟨_, _⟩ := rfl
@[simp] theorem cons_head (a : α) : ∀ (v : vector α n), (a :: v).head = a
| ⟨_, _⟩ := rfl
@[simp] theorem cons_tail (a : α) : ∀ (v : vector α n), (a :: v).tail = v
| ⟨_, _⟩ := rfl
@[simp] theorem to_list_of_fn : ∀ {n} (f : fin n → α), to_list (of_fn f) = list.of_fn f
| 0 f := rfl
| (n+1) f := by rw [of_fn, list.of_fn_succ, to_list_cons, to_list_of_fn]
@[simp] theorem mk_to_list :
∀ (v : vector α n) h, (⟨to_list v, h⟩ : vector α n) = v
| ⟨l, h₁⟩ h₂ := rfl
@[simp] lemma to_list_map {β : Type*} (v : vector α n) (f : α → β) : (v.map f).to_list =
v.to_list.map f := by cases v; refl
theorem nth_eq_nth_le : ∀ (v : vector α n) (i),
nth v i = v.to_list.nth_le i.1 (by rw to_list_length; exact i.2)
| ⟨l, h⟩ i := rfl
@[simp] lemma nth_map {β : Type*} (v : vector α n) (f : α → β) (i : fin n) :
(v.map f).nth i = f (v.nth i) :=
by simp [nth_eq_nth_le]
@[simp] theorem nth_of_fn {n} (f : fin n → α) (i) : nth (of_fn f) i = f i :=
by rw [nth_eq_nth_le, ← list.nth_le_of_fn f];
congr; apply to_list_of_fn
@[simp] theorem of_fn_nth (v : vector α n) : of_fn (nth v) = v :=
begin
rcases v with ⟨l, rfl⟩,
apply to_list_injective,
change nth ⟨l, eq.refl _⟩ with λ i, nth ⟨l, rfl⟩ i,
simpa only [to_list_of_fn] using list.of_fn_nth_le _
end
@[simp] theorem nth_tail : ∀ (v : vector α n.succ) (i : fin n),
nth (tail v) i = nth v i.succ
| ⟨a::l, e⟩ ⟨i, h⟩ := by simp [nth_eq_nth_le]; refl
@[simp] theorem tail_val : ∀ (v : vector α n.succ), v.tail.val = v.val.tail
| ⟨a::l, e⟩ := rfl
@[simp] theorem tail_of_fn {n : ℕ} (f : fin n.succ → α) :
tail (of_fn f) = of_fn (λ i, f i.succ) :=
(of_fn_nth _).symm.trans $ by congr; funext i; simp
lemma mem_iff_nth {a : α} {v : vector α n} : a ∈ v.to_list ↔ ∃ i, v.nth i = a :=
by simp only [list.mem_iff_nth_le, fin.exists_iff, vector.nth_eq_nth_le];
exact ⟨λ ⟨i, hi, h⟩, ⟨i, by rwa to_list_length at hi, h⟩,
λ ⟨i, hi, h⟩, ⟨i, by rwa to_list_length, h⟩⟩
lemma nodup_iff_nth_inj {v : vector α n} : v.to_list.nodup ↔ function.injective v.nth :=
begin
cases v with l hl,
subst hl,
simp only [list.nodup_iff_nth_le_inj],
split,
{ intros h i j hij,
cases i, cases j, simp [nth_eq_nth_le] at *, tauto },
{ intros h i j hi hj hij,
have := @h ⟨i, hi⟩ ⟨j, hj⟩, simp [nth_eq_nth_le] at *, tauto }
end
@[simp] lemma nth_mem (i : fin n) (v : vector α n) : v.nth i ∈ v.to_list :=
by rw [nth_eq_nth_le]; exact list.nth_le_mem _ _ _
theorem head'_to_list : ∀ (v : vector α n.succ),
(to_list v).head' = some (head v)
| ⟨a::l, e⟩ := rfl
def reverse (v : vector α n) : vector α n :=
⟨v.to_list.reverse, by simp⟩
@[simp] theorem nth_zero : ∀ (v : vector α n.succ), nth v 0 = head v
| ⟨a::l, e⟩ := rfl
@[simp] theorem head_of_fn
{n : ℕ} (f : fin n.succ → α) : head (of_fn f) = f 0 :=
by rw [← nth_zero, nth_of_fn]
@[simp] theorem nth_cons_zero
(a : α) (v : vector α n) : nth (a :: v) 0 = a :=
by simp [nth_zero]
@[simp] theorem nth_cons_succ
(a : α) (v : vector α n) (i : fin n) : nth (a :: v) i.succ = nth v i :=
by rw [← nth_tail, tail_cons]
def m_of_fn {m} [monad m] {α : Type u} : ∀ {n}, (fin n → m α) → m (vector α n)
| 0 f := pure nil
| (n+1) f := do a ← f 0, v ← m_of_fn (λi, f i.succ), pure (a :: v)
theorem m_of_fn_pure {m} [monad m] [is_lawful_monad m] {α} :
∀ {n} (f : fin n → α), @m_of_fn m _ _ _ (λ i, pure (f i)) = pure (of_fn f)
| 0 f := rfl
| (n+1) f := by simp [m_of_fn, @m_of_fn_pure n, of_fn]
def mmap {m} [monad m] {α} {β : Type u} (f : α → m β) :
∀ {n}, vector α n → m (vector β n)
| _ ⟨[], rfl⟩ := pure nil
| _ ⟨a::l, rfl⟩ := do h' ← f a, t' ← mmap ⟨l, rfl⟩, pure (h' :: t')
@[simp] theorem mmap_nil {m} [monad m] {α β} (f : α → m β) :
mmap f nil = pure nil := rfl
@[simp] theorem mmap_cons {m} [monad m] {α β} (f : α → m β) (a) :
∀ {n} (v : vector α n), mmap f (a::v) =
do h' ← f a, t' ← mmap f v, pure (h' :: t')
| _ ⟨l, rfl⟩ := rfl
@[ext] theorem ext : ∀ {v w : vector α n}
(h : ∀ m : fin n, vector.nth v m = vector.nth w m), v = w
| ⟨v, hv⟩ ⟨w, hw⟩ h := subtype.eq (list.ext_le (by rw [hv, hw])
(λ m hm hn, h ⟨m, hv ▸ hm⟩))
instance zero_subsingleton : subsingleton (vector α 0) :=
⟨λ _ _, vector.ext (λ m, fin.elim0 m)⟩
def to_array : vector α n → array n α
| ⟨xs, h⟩ := cast (by rw h) xs.to_array
section insert_nth
variable {a : α}
def insert_nth (a : α) (i : fin (n+1)) (v : vector α n) : vector α (n+1) :=
⟨v.1.insert_nth i a,
begin
rw [list.length_insert_nth, v.2],
rw [v.2, ← nat.succ_le_succ_iff],
exact i.2
end⟩
lemma insert_nth_val {i : fin (n+1)} {v : vector α n} :
(v.insert_nth a i).val = v.val.insert_nth i.1 a :=
rfl
@[simp] lemma remove_nth_val {i : fin n} :
∀{v : vector α n}, (remove_nth i v).val = v.val.remove_nth i
| ⟨l, hl⟩ := rfl
lemma remove_nth_insert_nth {v : vector α n} {i : fin (n+1)} : remove_nth i (insert_nth a i v) = v :=
subtype.eq $ list.remove_nth_insert_nth i.1 v.1
lemma remove_nth_insert_nth_ne {v : vector α (n+1)} :
∀{i j : fin (n+2)} (h : i ≠ j),
remove_nth i (insert_nth a j v) = insert_nth a (i.pred_above j h.symm) (remove_nth (j.pred_above i h) v)
| ⟨i, hi⟩ ⟨j, hj⟩ ne :=
begin
have : i ≠ j := fin.vne_of_ne ne,
refine subtype.eq _,
dsimp [insert_nth, remove_nth, fin.pred_above, fin.cast_lt, -subtype.val_eq_coe],
rcases lt_trichotomy i j with h | h | h,
{ have h_nji : ¬ j < i := lt_asymm h,
have j_pos : 0 < j := lt_of_le_of_lt (zero_le i) h,
rw [dif_neg], swap, { exact h_nji },
rw [dif_pos], swap, { exact h },
rw [fin.coe_pred, fin.coe_mk, remove_nth_val, fin.coe_mk],
rw [list.insert_nth_remove_nth_of_ge, nat.sub_add_cancel j_pos],
{ rw [v.2], exact lt_of_lt_of_le h (nat.le_of_succ_le_succ hj) },
{ exact nat.le_sub_right_of_add_le h } },
{ exact (this h).elim },
{ have h_nij : ¬ i < j := lt_asymm h,
have i_pos : 0 < i := lt_of_le_of_lt (zero_le j) h,
rw [dif_pos], swap, { exact h },
rw [dif_neg], swap, { exact h_nij },
rw [fin.coe_mk, remove_nth_val, fin.coe_pred, fin.coe_mk],
rw [list.insert_nth_remove_nth_of_le, nat.sub_add_cancel i_pos],
{ show i - 1 + 1 ≤ v.val.length,
rw [v.2, nat.sub_add_cancel i_pos],
exact nat.le_of_lt_succ hi },
{ exact nat.le_sub_right_of_add_le h } }
end
lemma insert_nth_comm (a b : α) (i j : fin (n+1)) (h : i ≤ j) :
∀(v : vector α n), (v.insert_nth a i).insert_nth b j.succ = (v.insert_nth b j).insert_nth a i.cast_succ
| ⟨l, hl⟩ :=
begin
refine subtype.eq _,
simp only [insert_nth_val, fin.coe_succ, fin.cast_succ, fin.val_eq_coe, fin.coe_cast_add],
apply list.insert_nth_comm,
{ assumption },
{ rw hl, exact nat.le_of_succ_le_succ j.2 }
end
end insert_nth
section update_nth
/-- `update_nth v n a` replaces the `n`th element of `v` with `a` -/
def update_nth (v : vector α n) (i : fin n) (a : α) : vector α n :=
⟨v.1.update_nth i.1 a, by rw [list.update_nth_length, v.2]⟩
@[simp] lemma nth_update_nth_same (v : vector α n) (i : fin n) (a : α) :
(v.update_nth i a).nth i = a :=
by cases v; cases i; simp [vector.update_nth, vector.nth_eq_nth_le]
lemma nth_update_nth_of_ne {v : vector α n} {i j : fin n} (h : i ≠ j) (a : α) :
(v.update_nth i a).nth j = v.nth j :=
by cases v; cases i; cases j; simp [vector.update_nth, vector.nth_eq_nth_le,
list.nth_le_update_nth_of_ne (fin.vne_of_ne h)]
lemma nth_update_nth_eq_if {v : vector α n} {i j : fin n} (a : α) :
(v.update_nth i a).nth j = if i = j then a else v.nth j :=
by split_ifs; try {simp *}; try {rw nth_update_nth_of_ne}; assumption
end update_nth
end vector
namespace vector
section traverse
variables {F G : Type u → Type u}
variables [applicative F] [applicative G]
open applicative functor
open list (cons) nat
private def traverse_aux {α β : Type u} (f : α → F β) :
Π (x : list α), F (vector β x.length)
| [] := pure vector.nil
| (x::xs) := vector.cons <$> f x <*> traverse_aux xs
protected def traverse {α β : Type u} (f : α → F β) : vector α n → F (vector β n)
| ⟨v, Hv⟩ := cast (by rw Hv) $ traverse_aux f v
variables [is_lawful_applicative F] [is_lawful_applicative G]
variables {α β γ : Type u}
@[simp] protected lemma traverse_def
(f : α → F β) (x : α) : ∀ (xs : vector α n),
(x :: xs).traverse f = cons <$> f x <*> xs.traverse f :=
by rintro ⟨xs, rfl⟩; refl
protected lemma id_traverse : ∀ (x : vector α n), x.traverse id.mk = x :=
begin
rintro ⟨x, rfl⟩, dsimp [vector.traverse, cast],
induction x with x xs IH, {refl},
simp! [IH], refl
end
open function
protected lemma comp_traverse (f : β → F γ) (g : α → G β) : ∀ (x : vector α n),
vector.traverse (comp.mk ∘ functor.map f ∘ g) x =
comp.mk (vector.traverse f <$> vector.traverse g x) :=
by rintro ⟨x, rfl⟩; dsimp [vector.traverse, cast];
induction x with x xs; simp! [cast, *] with functor_norm;
[refl, simp [(∘)]]
protected lemma traverse_eq_map_id {α β} (f : α → β) : ∀ (x : vector α n),
x.traverse (id.mk ∘ f) = id.mk (map f x) :=
by rintro ⟨x, rfl⟩; simp!;
induction x; simp! * with functor_norm; refl
variable (η : applicative_transformation F G)
protected lemma naturality {α β : Type*}
(f : α → F β) : ∀ (x : vector α n),
η (x.traverse f) = x.traverse (@η _ ∘ f) :=
by rintro ⟨x, rfl⟩; simp! [cast];
induction x with x xs IH; simp! * with functor_norm
end traverse
instance : traversable.{u} (flip vector n) :=
{ traverse := @vector.traverse n,
map := λ α β, @vector.map.{u u} α β n }
instance : is_lawful_traversable.{u} (flip vector n) :=
{ id_traverse := @vector.id_traverse n,
comp_traverse := @vector.comp_traverse n,
traverse_eq_map_id := @vector.traverse_eq_map_id n,
naturality := @vector.naturality n,
id_map := by intros; cases x; simp! [(<$>)],
comp_map := by intros; cases x; simp! [(<$>)] }
end vector
|
88e36c7df337cd884b9f7d52abfc16c0c3979b7f | bdc51328652176125c43c2c9f2d3e4398f127ccb | /src/DFA.lean | 4894f9b80e368437d8bbabf4c6a547990063c7aa | [] | no_license | atarnoam/lean-automata | d6ca17387b8e0ac6d7c21f12e78d26c237a57cd2 | 46c69ddaa142913b1f43ef57f700f2481cdfba76 | refs/heads/main | 1,678,898,675,345 | 1,614,977,921,000 | 1,614,977,921,000 | 344,927,186 | 6 | 1 | null | null | null | null | UTF-8 | Lean | false | false | 4,519 | lean | import computability.DFA
import computability.language
import data.fintype.basic
import data.list
import language
universes u v w
namespace DFA
variables {α : Type u}
variables {σ τ : Type v}
section basics
variables {A : DFA α σ} (p : σ) (a : α) (x y : list α)
@[simp] lemma eval_from_nil : A.eval_from p [] = p :=
list.foldl_nil _ _
@[simp] lemma eval_from_cons : A.eval_from p (a :: x) = A.eval_from (A.step p a) x :=
list.foldl_cons _ _ _ _
@[simp] lemma eval_def : A.eval x = A.eval_from A.start x := rfl
attribute [simp] mem_accepts
end basics
section intersection
/-!
### Intersection automaton
Here we construct from two DFAs a DFA whose language is the intersection of the two DFAs, and prove it.
-/
variables (A : DFA α σ) (B : DFA α τ) (s : σ) (t : τ) (a : α) (x : list α)
/--
Given two DFAs, returns a DFA whose language is the intersection of the two DFAs' languages.
-/
def inter : DFA α (σ × τ):=
{
step := λ ⟨s, t⟩ a, ⟨A.step s a, B.step t a⟩,
start := ⟨A.start, B.start⟩,
accept := { st | st.1 ∈ A.accept ∧ st.2 ∈ B.accept}
}
@[simp] lemma inter_step : (inter A B).step (s, t) a = (A.step s a, B.step t a) := rfl
@[simp] lemma inter_start : (inter A B).start = (A.start, B.start) := rfl
@[simp] lemma inter_accept : (s, t) ∈ (inter A B).accept ↔ s ∈ A.accept ∧ t ∈ B.accept :=
iff.refl _
@[simp]
lemma inter_eval_from : eval_from (inter A B) (s, t) x = (eval_from A s x, eval_from B t x) :=
begin
induction x with a x ih generalizing s t,
{ tauto },
{ simp [ih _ _] }
end
@[simp]
lemma inter_accepts : accepts (inter A B) = (accepts A) ⊓ (accepts B) :=
by {ext, simp}
end intersection
section complement
/-!
### Complement automaton
Here we construct a DFA whose language is the complement of the given DFA's language.
-/
variables (A : DFA α σ) (s : σ) (a : α) (x : list α)
/--
Given a DFA, returns a DFA whose language is the complement of the given DFA's language.
-/
def compl : DFA α σ :=
{
step := A.step,
start := A.start,
accept := { s | s ∉ A.accept }
}
@[simp] lemma compl_step : A.compl.step = A.step := rfl
@[simp] lemma compl_start : A.compl.start = A.start := rfl
@[simp] lemma compl_accept : s ∈ A.compl.accept ↔ s ∉ A.accept := by refl
@[simp]
lemma compl_eval_from : eval_from A.compl s x = eval_from A s x :=
begin
induction x with a x ih generalizing s,
{ tauto },
{ simp [ih _] }
end
@[simp]
lemma compl_accepts : accepts (compl A) = (accepts A)ᶜ :=
by {ext, simp}
end complement
section relation
/-!
### Equivalence relation on `list α`
Here we give the basics of the equivalence relation on `list α` that we get for every DFA `A`,
defined as:
`x ≈ y ↔ A.eval x = A.eval y`.
-/
variables (A : DFA α σ)
/--
A relation on `list α`, identifying `x, y` if `A.eval x = A.eval y`.
-/
definition rel : list α → list α → Prop :=
λ x y, A.eval x = A.eval y
@[simp] lemma rel_def {x y : list α} : rel A x y ↔ A.eval x = A.eval y := by refl
lemma rel_refl : reflexive (rel A) := λ _, by rw rel_def
lemma rel_symm : symmetric (rel A) := λ _ _ hxy, eq.symm hxy
lemma rel_trans : transitive (rel A) := λ _ _ _ hxy hyz, eq.trans hxy hyz
lemma rel_equiv : equivalence (rel A) := ⟨rel_refl A, rel_symm A, rel_trans A⟩
instance space.setoid : setoid (list α) := setoid.mk A.rel A.rel_equiv
definition space := quotient (space.setoid A)
variable {A}
definition space.mk (x : list α) : space A := @quotient.mk _ (space.setoid A) x
@[simp] lemma space.mk_def (x : list α) : space.mk x = @quotient.mk _ (space.setoid A) x := rfl
@[simp] lemma space.mk_def' (x : list α) : @quotient.mk' _ (space.setoid A) x = space.mk x := rfl
variable (A)
-- The canonical map. We show it is injective, as a part of the proof of Myhill-Nerode.
def to_states : space A → σ :=
begin
apply quot.lift A.eval,
intros x y rab,
rw (rel_def A).1 rab
end
@[simp] lemma to_states_def (x : list α) : to_states A (space.mk x) = A.eval x := rfl
lemma injective_to_states : function.injective (to_states A) :=
begin
apply @quotient.ind₂' (list α) (list α) _ _ (λ ex ey, to_states A ex = to_states A ey → ex = ey) ,
intros x y h,
repeat {rw space.mk_def' _ at h, rw f_def A _ at h},
simp,
exact h,
end
-- What we actually care about, sadly noncomputable :(
noncomputable instance fintype_space_of_fintype_states [fintype σ] : fintype (space A) :=
fintype.of_injective (to_states A) (injective_to_states A)
end relation
end DFA
|
697716519c787a1ed71cddef560d647e0a7af663 | 5ae26df177f810c5006841e9c73dc56e01b978d7 | /src/category_theory/monoidal/functor.lean | d4b1bf965227bff5cc824d0e26bd6a9e935c85cf | [
"Apache-2.0"
] | permissive | ChrisHughes24/mathlib | 98322577c460bc6b1fe5c21f42ce33ad1c3e5558 | a2a867e827c2a6702beb9efc2b9282bd801d5f9a | refs/heads/master | 1,583,848,251,477 | 1,565,164,247,000 | 1,565,164,247,000 | 129,409,993 | 0 | 1 | Apache-2.0 | 1,565,164,817,000 | 1,523,628,059,000 | Lean | UTF-8 | Lean | false | false | 6,665 | lean | /-
Copyright (c) 2018 Michael Jendrusch. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Michael Jendrusch, Scott Morrison
-/
import category_theory.monoidal.category
open category_theory
universes v₁ v₂ v₃ u₁ u₂ u₃
open category_theory.category
open category_theory.functor
namespace category_theory
section
open monoidal_category
variables (C : Type u₁) [𝒞 : monoidal_category.{v₁} C]
(D : Type u₂) [𝒟 : monoidal_category.{v₂} D]
include 𝒞 𝒟
structure lax_monoidal_functor extends C ⥤ D :=
-- unit morphism
(ε : tensor_unit D ⟶ obj (tensor_unit C))
-- tensorator
(μ : Π X Y : C, (obj X) ⊗ (obj Y) ⟶ obj (X ⊗ Y))
(μ_natural' : ∀ {X Y X' Y' : C}
(f : X ⟶ Y) (g : X' ⟶ Y'),
((map f) ⊗ (map g)) ≫ μ Y Y' = μ X X' ≫ map (f ⊗ g)
. obviously)
-- associativity of the tensorator
(associativity' : ∀ (X Y Z : C),
(μ X Y ⊗ 𝟙 (obj Z)) ≫ μ (X ⊗ Y) Z ≫ map (associator X Y Z).hom
= (associator (obj X) (obj Y) (obj Z)).hom ≫ (𝟙 (obj X) ⊗ μ Y Z) ≫ μ X (Y ⊗ Z)
. obviously)
-- unitality
(left_unitality' : ∀ X : C,
(left_unitor (obj X)).hom
= (ε ⊗ 𝟙 (obj X)) ≫ μ (tensor_unit C) X ≫ map (left_unitor X).hom
. obviously)
(right_unitality' : ∀ X : C,
(right_unitor (obj X)).hom
= (𝟙 (obj X) ⊗ ε) ≫ μ X (tensor_unit C) ≫ map (right_unitor X).hom
. obviously)
restate_axiom lax_monoidal_functor.μ_natural'
attribute [simp] lax_monoidal_functor.μ_natural
restate_axiom lax_monoidal_functor.left_unitality'
attribute [simp] lax_monoidal_functor.left_unitality
restate_axiom lax_monoidal_functor.right_unitality'
attribute [simp] lax_monoidal_functor.right_unitality
restate_axiom lax_monoidal_functor.associativity'
attribute [simp] lax_monoidal_functor.associativity
-- When `rewrite_search` lands, add @[search] attributes to
-- lax_monoidal_functor.μ_natural lax_monoidal_functor.left_unitality
-- lax_monoidal_functor.right_unitality lax_monoidal_functor.associativity
structure monoidal_functor
extends lax_monoidal_functor.{v₁ v₂} C D :=
(ε_is_iso : is_iso ε . obviously)
(μ_is_iso : Π X Y : C, is_iso (μ X Y) . obviously)
attribute [instance] monoidal_functor.ε_is_iso monoidal_functor.μ_is_iso
variables {C D}
def monoidal_functor.ε_iso (F : monoidal_functor.{v₁ v₂} C D) :
tensor_unit D ≅ F.obj (tensor_unit C) :=
as_iso F.ε
def monoidal_functor.μ_iso (F : monoidal_functor.{v₁ v₂} C D) (X Y : C) :
(F.obj X) ⊗ (F.obj Y) ≅ F.obj (X ⊗ Y) :=
as_iso (F.μ X Y)
end
open monoidal_category
namespace monoidal_functor
section
-- In order to express the tensorator as a natural isomorphism,
-- we need to be in at least `Type 0`, so we have products.
variables {C : Type u₁} [𝒞 : monoidal_category.{v₁+1} C]
variables {D : Type u₂} [𝒟 : monoidal_category.{v₂+1} D]
include 𝒞 𝒟
def μ_nat_iso (F : monoidal_functor.{v₁+1 v₂+1} C D) :
(functor.prod F.to_functor F.to_functor) ⋙ (tensor D) ≅ (tensor C) ⋙ F.to_functor :=
nat_iso.of_components
(by { intros, apply F.μ_iso })
(by { intros, apply F.to_lax_monoidal_functor.μ_natural })
end
section
variables (C : Type u₁) [𝒞 : monoidal_category.{v₁} C]
include 𝒞
def id : monoidal_functor.{v₁ v₁} C C :=
{ ε := 𝟙 _,
μ := λ X Y, 𝟙 _,
.. functor.id C }
@[simp] lemma id_obj (X : C) : (monoidal_functor.id C).obj X = X := rfl
@[simp] lemma id_map {X X' : C} (f : X ⟶ X') : (monoidal_functor.id C).map f = f := rfl
@[simp] lemma id_ε : (monoidal_functor.id C).ε = 𝟙 _ := rfl
@[simp] lemma id_μ (X Y) : (monoidal_functor.id C).μ X Y = 𝟙 _ := rfl
end
end monoidal_functor
variables {C : Type u₁} [𝒞 : monoidal_category.{v₁} C]
variables {D : Type u₂} [𝒟 : monoidal_category.{v₂} D]
variables {E : Type u₃} [ℰ : monoidal_category.{v₃} E]
include 𝒞 𝒟 ℰ
namespace lax_monoidal_functor
variables (F : lax_monoidal_functor.{v₁ v₂} C D) (G : lax_monoidal_functor.{v₂ v₃} D E)
-- The proofs here are horrendous; rewrite_search helps a lot.
def comp : lax_monoidal_functor.{v₁ v₃} C E :=
{ ε := G.ε ≫ (G.map F.ε),
μ := λ X Y, G.μ (F.obj X) (F.obj Y) ≫ G.map (F.μ X Y),
μ_natural' := λ _ _ _ _ f g,
begin
simp only [functor.comp_map, assoc],
rw [←category.assoc, lax_monoidal_functor.μ_natural, category.assoc, ←map_comp, ←map_comp,
←lax_monoidal_functor.μ_natural]
end,
associativity' := λ X Y Z,
begin
dsimp,
rw id_tensor_comp,
slice_rhs 3 4 { rw [← G.to_functor.map_id, G.μ_natural], },
slice_rhs 1 3 { rw ←G.associativity, },
rw comp_tensor_id,
slice_lhs 2 3 { rw [← G.to_functor.map_id, G.μ_natural], },
rw [category.assoc, category.assoc, category.assoc, category.assoc, category.assoc,
←G.to_functor.map_comp, ←G.to_functor.map_comp, ←G.to_functor.map_comp, ←G.to_functor.map_comp,
F.associativity],
end,
left_unitality' := λ X,
begin
dsimp,
rw [G.left_unitality, comp_tensor_id, category.assoc, category.assoc],
apply congr_arg,
rw [F.left_unitality, map_comp, ←nat_trans.id_app, ←category.assoc,
←lax_monoidal_functor.μ_natural, nat_trans.id_app, map_id, ←category.assoc, map_comp],
end,
right_unitality' := λ X,
begin
dsimp,
rw [G.right_unitality, id_tensor_comp, category.assoc, category.assoc],
apply congr_arg,
rw [F.right_unitality, map_comp, ←nat_trans.id_app, ←category.assoc,
←lax_monoidal_functor.μ_natural, nat_trans.id_app, map_id, ←category.assoc, map_comp],
end,
.. (F.to_functor) ⋙ (G.to_functor) }.
@[simp] lemma comp_obj (X : C) : (F.comp G).obj X = G.obj (F.obj X) := rfl
@[simp] lemma comp_map {X X' : C} (f : X ⟶ X') :
(F.comp G).map f = (G.map (F.map f) : G.obj (F.obj X) ⟶ G.obj (F.obj X')) := rfl
@[simp] lemma comp_ε : (F.comp G).ε = G.ε ≫ (G.map F.ε) := rfl
@[simp] lemma comp_μ (X Y : C) : (F.comp G).μ X Y = G.μ (F.obj X) (F.obj Y) ≫ G.map (F.μ X Y) := rfl
end lax_monoidal_functor
namespace monoidal_functor
variables (F : monoidal_functor.{v₁ v₂} C D) (G : monoidal_functor.{v₂ v₃} D E)
def comp : monoidal_functor.{v₁ v₃} C E :=
{ ε_is_iso := by { dsimp, apply_instance }, -- TODO tidy would get this if we deferred ext
μ_is_iso := by { dsimp, apply_instance }, -- TODO as above
.. (F.to_lax_monoidal_functor).comp (G.to_lax_monoidal_functor) }.
end monoidal_functor
end category_theory
|
bad8ee8281b349874880a2930bb5436fe10474a5 | 8cae430f0a71442d02dbb1cbb14073b31048e4b0 | /src/linear_algebra/basis.lean | c7f2f38be3cd79adaf218490ddd95718fd827084 | [
"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 | 57,800 | 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, Alexander Bentkamp
-/
import algebra.big_operators.finsupp
import algebra.big_operators.finprod
import data.fintype.big_operators
import linear_algebra.finsupp
import linear_algebra.linear_independent
import linear_algebra.linear_pmap
import linear_algebra.projection
/-!
# Bases
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
This file defines bases in a module or vector space.
It is inspired by Isabelle/HOL's linear algebra, and hence indirectly by HOL Light.
## Main definitions
All definitions are given for families of vectors, i.e. `v : ι → M` where `M` is the module or
vector space and `ι : Type*` is an arbitrary indexing type.
* `basis ι R M` is the type of `ι`-indexed `R`-bases for a module `M`,
represented by a linear equiv `M ≃ₗ[R] ι →₀ R`.
* the basis vectors of a basis `b : basis ι R M` are available as `b i`, where `i : ι`
* `basis.repr` is the isomorphism sending `x : M` to its coordinates `basis.repr x : ι →₀ R`.
The converse, turning this isomorphism into a basis, is called `basis.of_repr`.
* If `ι` is finite, there is a variant of `repr` called `basis.equiv_fun b : M ≃ₗ[R] ι → R`
(saving you from having to work with `finsupp`). The converse, turning this isomorphism into
a basis, is called `basis.of_equiv_fun`.
* `basis.constr hv f` constructs a linear map `M₁ →ₗ[R] M₂` given the values `f : ι → M₂` at the
basis elements `⇑b : ι → M₁`.
* `basis.reindex` uses an equiv to map a basis to a different indexing set.
* `basis.map` uses a linear equiv to map a basis to a different module.
## Main statements
* `basis.mk`: a linear independent set of vectors spanning the whole module determines a basis
* `basis.ext` states that two linear maps are equal if they coincide on a basis.
Similar results are available for linear equivs (if they coincide on the basis vectors),
elements (if their coordinates coincide) and the functions `b.repr` and `⇑b`.
* `basis.of_vector_space` states that every vector space has a basis.
## Implementation notes
We use families instead of sets because it allows us to say that two identical vectors are linearly
dependent. For bases, this is useful as well because we can easily derive ordered bases by using an
ordered index type `ι`.
## Tags
basis, bases
-/
noncomputable theory
universe u
open function set submodule
open_locale big_operators
variables {ι : Type*} {ι' : Type*} {R : Type*} {R₂ : Type*} {K : Type*}
variables {M : Type*} {M' M'' : Type*} {V : Type u} {V' : Type*}
section module
variables [semiring R]
variables [add_comm_monoid M] [module R M] [add_comm_monoid M'] [module R M']
section
variables (ι) (R) (M)
/-- A `basis ι R M` for a module `M` is the type of `ι`-indexed `R`-bases of `M`.
The basis vectors are available as `coe_fn (b : basis ι R M) : ι → M`.
To turn a linear independent family of vectors spanning `M` into a basis, use `basis.mk`.
They are internally represented as linear equivs `M ≃ₗ[R] (ι →₀ R)`,
available as `basis.repr`.
-/
structure basis := of_repr :: (repr : M ≃ₗ[R] (ι →₀ R))
end
instance unique_basis [subsingleton R] : unique (basis ι R M) :=
⟨⟨⟨default⟩⟩, λ ⟨b⟩, by rw subsingleton.elim b⟩
namespace basis
instance : inhabited (basis ι R (ι →₀ R)) := ⟨basis.of_repr (linear_equiv.refl _ _)⟩
variables (b b₁ : basis ι R M) (i : ι) (c : R) (x : M)
section repr
lemma repr_injective : injective (repr : basis ι R M → M ≃ₗ[R] (ι →₀ R)) :=
λ f g h, by cases f; cases g; congr'
/-- `b i` is the `i`th basis vector. -/
instance fun_like : fun_like (basis ι R M) ι (λ _, M) :=
{ coe := λ b i, b.repr.symm (finsupp.single i 1),
coe_injective' := λ f g h, repr_injective $ linear_equiv.symm_bijective.injective begin
ext x,
rw [←finsupp.sum_single x, map_finsupp_sum, map_finsupp_sum],
congr' with i r,
have := congr_fun h i,
dsimp at this,
rw [←mul_one r, ←finsupp.smul_single', linear_equiv.map_smul, linear_equiv.map_smul, this],
end }
@[simp] lemma coe_of_repr (e : M ≃ₗ[R] (ι →₀ R)) :
⇑(of_repr e) = λ i, e.symm (finsupp.single i 1) :=
rfl
protected lemma injective [nontrivial R] : injective b :=
b.repr.symm.injective.comp (λ _ _, (finsupp.single_left_inj (one_ne_zero : (1 : R) ≠ 0)).mp)
lemma repr_symm_single_one : b.repr.symm (finsupp.single i 1) = b i := rfl
lemma repr_symm_single : b.repr.symm (finsupp.single i c) = c • b i :=
calc b.repr.symm (finsupp.single i c)
= b.repr.symm (c • finsupp.single i 1) : by rw [finsupp.smul_single', mul_one]
... = c • b i : by rw [linear_equiv.map_smul, repr_symm_single_one]
@[simp] lemma repr_self : b.repr (b i) = finsupp.single i 1 :=
linear_equiv.apply_symm_apply _ _
lemma repr_self_apply (j) [decidable (i = j)] :
b.repr (b i) j = if i = j then 1 else 0 :=
by rw [repr_self, finsupp.single_apply]
@[simp] lemma repr_symm_apply (v) : b.repr.symm v = finsupp.total ι M R b v :=
calc b.repr.symm v = b.repr.symm (v.sum finsupp.single) : by simp
... = ∑ i in v.support, b.repr.symm (finsupp.single i (v i)) :
by rw [finsupp.sum, linear_equiv.map_sum]
... = finsupp.total ι M R b v :
by simp [repr_symm_single, finsupp.total_apply, finsupp.sum]
@[simp] lemma coe_repr_symm : ↑b.repr.symm = finsupp.total ι M R b :=
linear_map.ext (λ v, b.repr_symm_apply v)
@[simp] lemma repr_total (v) : b.repr (finsupp.total _ _ _ b v) = v :=
by { rw ← b.coe_repr_symm, exact b.repr.apply_symm_apply v }
@[simp] lemma total_repr : finsupp.total _ _ _ b (b.repr x) = x :=
by { rw ← b.coe_repr_symm, exact b.repr.symm_apply_apply x }
lemma repr_range : (b.repr : M →ₗ[R] (ι →₀ R)).range = finsupp.supported R R univ :=
by rw [linear_equiv.range, finsupp.supported_univ]
lemma mem_span_repr_support {ι : Type*} (b : basis ι R M) (m : M) :
m ∈ span R (b '' (b.repr m).support) :=
(finsupp.mem_span_image_iff_total _).2 ⟨b.repr m, (by simp [finsupp.mem_supported_support])⟩
lemma repr_support_subset_of_mem_span {ι : Type*}
(b : basis ι R M) (s : set ι) {m : M} (hm : m ∈ span R (b '' s)) : ↑(b.repr m).support ⊆ s :=
begin
rcases (finsupp.mem_span_image_iff_total _).1 hm with ⟨l, hl, hlm⟩,
rwa [←hlm, repr_total, ←finsupp.mem_supported R l]
end
end repr
section coord
/-- `b.coord i` is the linear function giving the `i`'th coordinate of a vector
with respect to the basis `b`.
`b.coord i` is an element of the dual space. In particular, for
finite-dimensional spaces it is the `ι`th basis vector of the dual space.
-/
@[simps]
def coord : M →ₗ[R] R := (finsupp.lapply i) ∘ₗ ↑b.repr
lemma forall_coord_eq_zero_iff {x : M} :
(∀ i, b.coord i x = 0) ↔ x = 0 :=
iff.trans
(by simp only [b.coord_apply, finsupp.ext_iff, finsupp.zero_apply])
b.repr.map_eq_zero_iff
/-- The sum of the coordinates of an element `m : M` with respect to a basis. -/
noncomputable def sum_coords : M →ₗ[R] R :=
finsupp.lsum ℕ (λ i, linear_map.id) ∘ₗ (b.repr : M →ₗ[R] ι →₀ R)
@[simp] lemma coe_sum_coords : (b.sum_coords : M → R) = λ m, (b.repr m).sum (λ i, id) :=
rfl
lemma coe_sum_coords_eq_finsum : (b.sum_coords : M → R) = λ m, ∑ᶠ i, b.coord i m :=
begin
ext m,
simp only [basis.sum_coords, basis.coord, finsupp.lapply_apply, linear_map.id_coe,
linear_equiv.coe_coe, function.comp_app, finsupp.coe_lsum, linear_map.coe_comp,
finsum_eq_sum _ (b.repr m).finite_support, finsupp.sum, finset.finite_to_set_to_finset,
id.def, finsupp.fun_support_eq],
end
@[simp] lemma coe_sum_coords_of_fintype [fintype ι] : (b.sum_coords : M → R) = ∑ i, b.coord i :=
begin
ext m,
simp only [sum_coords, finsupp.sum_fintype, linear_map.id_coe, linear_equiv.coe_coe, coord_apply,
id.def, fintype.sum_apply, implies_true_iff, eq_self_iff_true, finsupp.coe_lsum,
linear_map.coe_comp],
end
@[simp] lemma sum_coords_self_apply : b.sum_coords (b i) = 1 :=
by simp only [basis.sum_coords, linear_map.id_coe, linear_equiv.coe_coe, id.def, basis.repr_self,
function.comp_app, finsupp.coe_lsum, linear_map.coe_comp, finsupp.sum_single_index]
lemma dvd_coord_smul (i : ι) (m : M) (r : R) : r ∣ b.coord i (r • m) :=
⟨b.coord i m, by simp⟩
lemma coord_repr_symm (b : basis ι R M) (i : ι) (f : ι →₀ R) :
b.coord i (b.repr.symm f) = f i :=
by simp only [repr_symm_apply, coord_apply, repr_total]
end coord
section ext
variables {R₁ : Type*} [semiring R₁] {σ : R →+* R₁} {σ' : R₁ →+* R}
variables [ring_hom_inv_pair σ σ'] [ring_hom_inv_pair σ' σ]
variables {M₁ : Type*} [add_comm_monoid M₁] [module R₁ M₁]
/-- Two linear maps are equal if they are equal on basis vectors. -/
theorem ext {f₁ f₂ : M →ₛₗ[σ] M₁} (h : ∀ i, f₁ (b i) = f₂ (b i)) : f₁ = f₂ :=
by { ext x,
rw [← b.total_repr x, finsupp.total_apply, finsupp.sum],
simp only [linear_map.map_sum, linear_map.map_smulₛₗ, h] }
include σ'
/-- Two linear equivs are equal if they are equal on basis vectors. -/
theorem ext' {f₁ f₂ : M ≃ₛₗ[σ] M₁} (h : ∀ i, f₁ (b i) = f₂ (b i)) : f₁ = f₂ :=
by { ext x,
rw [← b.total_repr x, finsupp.total_apply, finsupp.sum],
simp only [linear_equiv.map_sum, linear_equiv.map_smulₛₗ, h] }
omit σ'
/-- Two elements are equal iff their coordinates are equal. -/
lemma ext_elem_iff {x y : M} :
x = y ↔ (∀ i, b.repr x i = b.repr y i) :=
by simp only [← finsupp.ext_iff, embedding_like.apply_eq_iff_eq]
alias ext_elem_iff ↔ _ _root_.basis.ext_elem
lemma repr_eq_iff {b : basis ι R M} {f : M →ₗ[R] ι →₀ R} :
↑b.repr = f ↔ ∀ i, f (b i) = finsupp.single i 1 :=
⟨λ h i, h ▸ b.repr_self i,
λ h, b.ext (λ i, (b.repr_self i).trans (h i).symm)⟩
lemma repr_eq_iff' {b : basis ι R M} {f : M ≃ₗ[R] ι →₀ R} :
b.repr = f ↔ ∀ i, f (b i) = finsupp.single i 1 :=
⟨λ h i, h ▸ b.repr_self i,
λ h, b.ext' (λ i, (b.repr_self i).trans (h i).symm)⟩
lemma apply_eq_iff {b : basis ι R M} {x : M} {i : ι} :
b i = x ↔ b.repr x = finsupp.single i 1 :=
⟨λ h, h ▸ b.repr_self i,
λ h, b.repr.injective ((b.repr_self i).trans h.symm)⟩
/-- An unbundled version of `repr_eq_iff` -/
lemma repr_apply_eq (f : M → ι → R)
(hadd : ∀ x y, f (x + y) = f x + f y) (hsmul : ∀ (c : R) (x : M), f (c • x) = c • f x)
(f_eq : ∀ i, f (b i) = finsupp.single i 1) (x : M) (i : ι) :
b.repr x i = f x i :=
begin
let f_i : M →ₗ[R] R :=
{ to_fun := λ x, f x i,
map_add' := λ _ _, by rw [hadd, pi.add_apply],
map_smul' := λ _ _, by { simp [hsmul, pi.smul_apply] } },
have : (finsupp.lapply i) ∘ₗ ↑b.repr = f_i,
{ refine b.ext (λ j, _),
show b.repr (b j) i = f (b j) i,
rw [b.repr_self, f_eq] },
calc b.repr x i = f_i x : by { rw ← this, refl }
... = f x i : rfl
end
/-- Two bases are equal if they assign the same coordinates. -/
lemma eq_of_repr_eq_repr {b₁ b₂ : basis ι R M} (h : ∀ x i, b₁.repr x i = b₂.repr x i) : b₁ = b₂ :=
repr_injective $ by { ext, apply h }
/-- Two bases are equal if their basis vectors are the same. -/
@[ext] lemma eq_of_apply_eq {b₁ b₂ : basis ι R M} : (∀ i, b₁ i = b₂ i) → b₁ = b₂ := fun_like.ext _ _
end ext
section map
variables (f : M ≃ₗ[R] M')
/-- Apply the linear equivalence `f` to the basis vectors. -/
@[simps] protected def map : basis ι R M' :=
of_repr (f.symm.trans b.repr)
@[simp] lemma map_apply (i) : b.map f i = f (b i) := rfl
end map
section map_coeffs
variables {R' : Type*} [semiring R'] [module R' M] (f : R ≃+* R') (h : ∀ c (x : M), f c • x = c • x)
include f h b
local attribute [instance] has_smul.comp.is_scalar_tower
/-- If `R` and `R'` are isomorphic rings that act identically on a module `M`,
then a basis for `M` as `R`-module is also a basis for `M` as `R'`-module.
See also `basis.algebra_map_coeffs` for the case where `f` is equal to `algebra_map`.
-/
@[simps {simp_rhs := tt}]
def map_coeffs : basis ι R' M :=
begin
letI : module R' R := module.comp_hom R (↑f.symm : R' →+* R),
haveI : is_scalar_tower R' R M :=
{ smul_assoc := λ x y z, begin dsimp [(•)], rw [mul_smul, ←h, f.apply_symm_apply], end },
exact (of_repr $ (b.repr.restrict_scalars R').trans $
finsupp.map_range.linear_equiv (module.comp_hom.to_linear_equiv f.symm).symm )
end
lemma map_coeffs_apply (i : ι) : b.map_coeffs f h i = b i :=
apply_eq_iff.mpr $ by simp [f.to_add_equiv_eq_coe]
@[simp] lemma coe_map_coeffs : (b.map_coeffs f h : ι → M) = b :=
funext $ b.map_coeffs_apply f h
end map_coeffs
section reindex
variables (b' : basis ι' R M')
variables (e : ι ≃ ι')
/-- `b.reindex (e : ι ≃ ι')` is a basis indexed by `ι'` -/
def reindex : basis ι' R M :=
basis.of_repr (b.repr.trans (finsupp.dom_lcongr e))
lemma reindex_apply (i' : ι') : b.reindex e i' = b (e.symm i') :=
show (b.repr.trans (finsupp.dom_lcongr e)).symm (finsupp.single i' 1) =
b.repr.symm (finsupp.single (e.symm i') 1),
by rw [linear_equiv.symm_trans_apply, finsupp.dom_lcongr_symm, finsupp.dom_lcongr_single]
@[simp] lemma coe_reindex : (b.reindex e : ι' → M) = b ∘ e.symm :=
funext (b.reindex_apply e)
lemma repr_reindex_apply (i' : ι') : (b.reindex e).repr x i' = b.repr x (e.symm i') :=
show (finsupp.dom_lcongr e : _ ≃ₗ[R] _) (b.repr x) i' = _, by simp
@[simp] lemma repr_reindex : (b.reindex e).repr x = (b.repr x).map_domain e :=
fun_like.ext _ _ $ by simp [repr_reindex_apply]
@[simp] lemma reindex_refl : b.reindex (equiv.refl ι) = b :=
eq_of_apply_eq $ λ i, by simp
/-- `simp` can prove this as `basis.coe_reindex` + `equiv_like.range_comp` -/
lemma range_reindex : set.range (b.reindex e) = set.range b :=
by rw [coe_reindex, equiv_like.range_comp]
@[simp] lemma sum_coords_reindex : (b.reindex e).sum_coords = b.sum_coords :=
begin
ext x,
simp only [coe_sum_coords, repr_reindex],
exact finsupp.sum_map_domain_index (λ _, rfl) (λ _ _ _, rfl),
end
/-- `b.reindex_range` is a basis indexed by `range b`, the basis vectors themselves. -/
def reindex_range : basis (range b) R M :=
by haveI := classical.dec (nontrivial R); exact
if h : nontrivial R then
by letI := h; exact b.reindex (equiv.of_injective b (basis.injective b))
else
by letI : subsingleton R := not_nontrivial_iff_subsingleton.mp h; exact
basis.of_repr (module.subsingleton_equiv R M (range b))
lemma reindex_range_self (i : ι) (h := set.mem_range_self i) :
b.reindex_range ⟨b i, h⟩ = b i :=
begin
by_cases htr : nontrivial R,
{ letI := htr,
simp [htr, reindex_range, reindex_apply, equiv.apply_of_injective_symm b.injective,
subtype.coe_mk] },
{ letI : subsingleton R := not_nontrivial_iff_subsingleton.mp htr,
letI := module.subsingleton R M,
simp [reindex_range] }
end
lemma reindex_range_repr_self (i : ι) :
b.reindex_range.repr (b i) = finsupp.single ⟨b i, mem_range_self i⟩ 1 :=
calc b.reindex_range.repr (b i) = b.reindex_range.repr (b.reindex_range ⟨b i, mem_range_self i⟩) :
congr_arg _ (b.reindex_range_self _ _).symm
... = finsupp.single ⟨b i, mem_range_self i⟩ 1 : b.reindex_range.repr_self _
@[simp] lemma reindex_range_apply (x : range b) : b.reindex_range x = x :=
by { rcases x with ⟨bi, ⟨i, rfl⟩⟩, exact b.reindex_range_self i, }
lemma reindex_range_repr' (x : M) {bi : M} {i : ι} (h : b i = bi) :
b.reindex_range.repr x ⟨bi, ⟨i, h⟩⟩ = b.repr x i :=
begin
nontriviality,
subst h,
refine (b.repr_apply_eq (λ x i, b.reindex_range.repr x ⟨b i, _⟩) _ _ _ x i).symm,
{ intros x y,
ext i,
simp only [pi.add_apply, linear_equiv.map_add, finsupp.coe_add] },
{ intros c x,
ext i,
simp only [pi.smul_apply, linear_equiv.map_smul, finsupp.coe_smul] },
{ intros i,
ext j,
simp only [reindex_range_repr_self],
refine @finsupp.single_apply_left _ _ _ _ (λ i, (⟨b i, _⟩ : set.range b)) _ _ _ _,
exact λ i j h, b.injective (subtype.mk.inj h) }
end
@[simp] lemma reindex_range_repr (x : M) (i : ι) (h := set.mem_range_self i) :
b.reindex_range.repr x ⟨b i, h⟩ = b.repr x i :=
b.reindex_range_repr' _ rfl
section fintype
variables [fintype ι] [decidable_eq M]
/-- `b.reindex_finset_range` is a basis indexed by `finset.univ.image b`,
the finite set of basis vectors themselves. -/
def reindex_finset_range : basis (finset.univ.image b) R M :=
b.reindex_range.reindex ((equiv.refl M).subtype_equiv (by simp))
lemma reindex_finset_range_self (i : ι) (h := finset.mem_image_of_mem b (finset.mem_univ i)) :
b.reindex_finset_range ⟨b i, h⟩ = b i :=
by { rw [reindex_finset_range, reindex_apply, reindex_range_apply], refl }
@[simp] lemma reindex_finset_range_apply (x : finset.univ.image b) :
b.reindex_finset_range x = x :=
by { rcases x with ⟨bi, hbi⟩, rcases finset.mem_image.mp hbi with ⟨i, -, rfl⟩,
exact b.reindex_finset_range_self i }
lemma reindex_finset_range_repr_self (i : ι) :
b.reindex_finset_range.repr (b i) =
finsupp.single ⟨b i, finset.mem_image_of_mem b (finset.mem_univ i)⟩ 1 :=
begin
ext ⟨bi, hbi⟩,
rw [reindex_finset_range, repr_reindex, finsupp.map_domain_equiv_apply, reindex_range_repr_self],
convert finsupp.single_apply_left ((equiv.refl M).subtype_equiv _).symm.injective _ _ _,
refl
end
@[simp] lemma reindex_finset_range_repr (x : M) (i : ι)
(h := finset.mem_image_of_mem b (finset.mem_univ i)) :
b.reindex_finset_range.repr x ⟨b i, h⟩ = b.repr x i :=
by simp [reindex_finset_range]
end fintype
end reindex
protected lemma linear_independent : linear_independent R b :=
linear_independent_iff.mpr $ λ l hl,
calc l = b.repr (finsupp.total _ _ _ b l) : (b.repr_total l).symm
... = 0 : by rw [hl, linear_equiv.map_zero]
protected lemma ne_zero [nontrivial R] (i) : b i ≠ 0 :=
b.linear_independent.ne_zero i
protected lemma mem_span (x : M) : x ∈ span R (range b) :=
by { rw [← b.total_repr x, finsupp.total_apply, finsupp.sum],
exact submodule.sum_mem _ (λ i hi, submodule.smul_mem _ _ (submodule.subset_span ⟨i, rfl⟩)) }
protected lemma span_eq : span R (range b) = ⊤ :=
eq_top_iff.mpr $ λ x _, b.mem_span x
lemma index_nonempty (b : basis ι R M) [nontrivial M] : nonempty ι :=
begin
obtain ⟨x, y, ne⟩ : ∃ (x y : M), x ≠ y := nontrivial.exists_pair_ne,
obtain ⟨i, _⟩ := not_forall.mp (mt b.ext_elem_iff.2 ne),
exact ⟨i⟩
end
/-- If the submodule `P` has a basis, `x ∈ P` iff it is a linear combination of basis vectors. -/
lemma mem_submodule_iff {P : submodule R M} (b : basis ι R P) {x : M} :
x ∈ P ↔ ∃ (c : ι →₀ R), x = finsupp.sum c (λ i x, x • b i) :=
begin
conv_lhs { rw [← P.range_subtype, ← submodule.map_top, ← b.span_eq, submodule.map_span,
← set.range_comp, ← finsupp.range_total] },
simpa only [@eq_comm _ x],
end
section constr
variables (S : Type*) [semiring S] [module S M']
variables [smul_comm_class R S M']
/-- Construct a linear map given the value at the basis.
This definition is parameterized over an extra `semiring S`,
such that `smul_comm_class R S M'` holds.
If `R` is commutative, you can set `S := R`; if `R` is not commutative,
you can recover an `add_equiv` by setting `S := ℕ`.
See library note [bundled maps over different rings].
-/
def constr : (ι → M') ≃ₗ[S] (M →ₗ[R] M') :=
{ to_fun := λ f, (finsupp.total M' M' R id).comp $ (finsupp.lmap_domain R R f) ∘ₗ ↑b.repr,
inv_fun := λ f i, f (b i),
left_inv := λ f, by { ext, simp },
right_inv := λ f, by { refine b.ext (λ i, _), simp },
map_add' := λ f g, by { refine b.ext (λ i, _), simp },
map_smul' := λ c f, by { refine b.ext (λ i, _), simp } }
theorem constr_def (f : ι → M') :
b.constr S f = (finsupp.total M' M' R id) ∘ₗ ((finsupp.lmap_domain R R f) ∘ₗ ↑b.repr) :=
rfl
theorem constr_apply (f : ι → M') (x : M) :
b.constr S f x = (b.repr x).sum (λ b a, a • f b) :=
by { simp only [constr_def, linear_map.comp_apply, finsupp.lmap_domain_apply, finsupp.total_apply],
rw finsupp.sum_map_domain_index; simp [add_smul] }
@[simp] lemma constr_basis (f : ι → M') (i : ι) :
(b.constr S f : M → M') (b i) = f i :=
by simp [basis.constr_apply, b.repr_self]
lemma constr_eq {g : ι → M'} {f : M →ₗ[R] M'}
(h : ∀i, g i = f (b i)) : b.constr S g = f :=
b.ext $ λ i, (b.constr_basis S g i).trans (h i)
lemma constr_self (f : M →ₗ[R] M') : b.constr S (λ i, f (b i)) = f :=
b.constr_eq S $ λ x, rfl
lemma constr_range [nonempty ι] {f : ι → M'} :
(b.constr S f).range = span R (range f) :=
by rw [b.constr_def S f, linear_map.range_comp, linear_map.range_comp, linear_equiv.range,
← finsupp.supported_univ, finsupp.lmap_domain_supported, ←set.image_univ,
← finsupp.span_image_eq_map_total, set.image_id]
@[simp]
lemma constr_comp (f : M' →ₗ[R] M') (v : ι → M') :
b.constr S (f ∘ v) = f.comp (b.constr S v) :=
b.ext (λ i, by simp only [basis.constr_basis, linear_map.comp_apply])
end constr
section equiv
variables (b' : basis ι' R M') (e : ι ≃ ι')
variables [add_comm_monoid M''] [module R M'']
/-- If `b` is a basis for `M` and `b'` a basis for `M'`, and the index types are equivalent,
`b.equiv b' e` is a linear equivalence `M ≃ₗ[R] M'`, mapping `b i` to `b' (e i)`. -/
protected def equiv : M ≃ₗ[R] M' :=
b.repr.trans (b'.reindex e.symm).repr.symm
@[simp] lemma equiv_apply : b.equiv b' e (b i) = b' (e i) :=
by simp [basis.equiv]
@[simp] lemma equiv_refl :
b.equiv b (equiv.refl ι) = linear_equiv.refl R M :=
b.ext' (λ i, by simp)
@[simp] lemma equiv_symm : (b.equiv b' e).symm = b'.equiv b e.symm :=
b'.ext' $ λ i, (b.equiv b' e).injective (by simp)
@[simp] lemma equiv_trans {ι'' : Type*} (b'' : basis ι'' R M'')
(e : ι ≃ ι') (e' : ι' ≃ ι'') :
(b.equiv b' e).trans (b'.equiv b'' e') = b.equiv b'' (e.trans e') :=
b.ext' (λ i, by simp)
@[simp]
lemma map_equiv (b : basis ι R M) (b' : basis ι' R M') (e : ι ≃ ι') :
b.map (b.equiv b' e) = b'.reindex e.symm :=
by { ext i, simp }
end equiv
section prod
variables (b' : basis ι' R M')
/-- `basis.prod` maps a `ι`-indexed basis for `M` and a `ι'`-indexed basis for `M'`
to a `ι ⊕ ι'`-index basis for `M × M'`.
For the specific case of `R × R`, see also `basis.fin_two_prod`. -/
protected def prod : basis (ι ⊕ ι') R (M × M') :=
of_repr ((b.repr.prod b'.repr).trans (finsupp.sum_finsupp_lequiv_prod_finsupp R).symm)
@[simp]
lemma prod_repr_inl (x) (i) : (b.prod b').repr x (sum.inl i) = b.repr x.1 i := rfl
@[simp]
lemma prod_repr_inr (x) (i) : (b.prod b').repr x (sum.inr i) = b'.repr x.2 i := rfl
lemma prod_apply_inl_fst (i) :
(b.prod b' (sum.inl i)).1 = b i :=
b.repr.injective $ by
{ ext j,
simp only [basis.prod, basis.coe_of_repr, linear_equiv.symm_trans_apply, linear_equiv.prod_symm,
linear_equiv.prod_apply, b.repr.apply_symm_apply, linear_equiv.symm_symm, repr_self,
equiv.to_fun_as_coe, finsupp.fst_sum_finsupp_lequiv_prod_finsupp],
apply finsupp.single_apply_left sum.inl_injective }
lemma prod_apply_inr_fst (i) :
(b.prod b' (sum.inr i)).1 = 0 :=
b.repr.injective $ by
{ ext i,
simp only [basis.prod, basis.coe_of_repr, linear_equiv.symm_trans_apply, linear_equiv.prod_symm,
linear_equiv.prod_apply, b.repr.apply_symm_apply, linear_equiv.symm_symm, repr_self,
equiv.to_fun_as_coe, finsupp.fst_sum_finsupp_lequiv_prod_finsupp, linear_equiv.map_zero,
finsupp.zero_apply],
apply finsupp.single_eq_of_ne sum.inr_ne_inl }
lemma prod_apply_inl_snd (i) :
(b.prod b' (sum.inl i)).2 = 0 :=
b'.repr.injective $ by
{ ext j,
simp only [basis.prod, basis.coe_of_repr, linear_equiv.symm_trans_apply, linear_equiv.prod_symm,
linear_equiv.prod_apply, b'.repr.apply_symm_apply, linear_equiv.symm_symm, repr_self,
equiv.to_fun_as_coe, finsupp.snd_sum_finsupp_lequiv_prod_finsupp, linear_equiv.map_zero,
finsupp.zero_apply],
apply finsupp.single_eq_of_ne sum.inl_ne_inr }
lemma prod_apply_inr_snd (i) :
(b.prod b' (sum.inr i)).2 = b' i :=
b'.repr.injective $ by
{ ext i,
simp only [basis.prod, basis.coe_of_repr, linear_equiv.symm_trans_apply, linear_equiv.prod_symm,
linear_equiv.prod_apply, b'.repr.apply_symm_apply, linear_equiv.symm_symm, repr_self,
equiv.to_fun_as_coe, finsupp.snd_sum_finsupp_lequiv_prod_finsupp],
apply finsupp.single_apply_left sum.inr_injective }
@[simp]
lemma prod_apply (i) :
b.prod b' i = sum.elim (linear_map.inl R M M' ∘ b) (linear_map.inr R M M' ∘ b') i :=
by { ext; cases i; simp only [prod_apply_inl_fst, sum.elim_inl, linear_map.inl_apply,
prod_apply_inr_fst, sum.elim_inr, linear_map.inr_apply,
prod_apply_inl_snd, prod_apply_inr_snd, comp_app] }
end prod
section no_zero_smul_divisors
-- Can't be an instance because the basis can't be inferred.
protected lemma no_zero_smul_divisors [no_zero_divisors R] (b : basis ι R M) :
no_zero_smul_divisors R M :=
⟨λ c x hcx, or_iff_not_imp_right.mpr (λ hx, begin
rw [← b.total_repr x, ← linear_map.map_smul] at hcx,
have := linear_independent_iff.mp b.linear_independent (c • b.repr x) hcx,
rw smul_eq_zero at this,
exact this.resolve_right (λ hr, hx (b.repr.map_eq_zero_iff.mp hr))
end)⟩
protected lemma smul_eq_zero [no_zero_divisors R] (b : basis ι R M) {c : R} {x : M} :
c • x = 0 ↔ c = 0 ∨ x = 0 :=
@smul_eq_zero _ _ _ _ _ b.no_zero_smul_divisors _ _
lemma _root_.eq_bot_of_rank_eq_zero [no_zero_divisors R] (b : basis ι R M) (N : submodule R M)
(rank_eq : ∀ {m : ℕ} (v : fin m → N),
linear_independent R (coe ∘ v : fin m → M) → m = 0) :
N = ⊥ :=
begin
rw submodule.eq_bot_iff,
intros x hx,
contrapose! rank_eq with x_ne,
refine ⟨1, λ _, ⟨x, hx⟩, _, one_ne_zero⟩,
rw fintype.linear_independent_iff,
rintros g sum_eq i,
cases i,
simp only [function.const_apply, fin.default_eq_zero, submodule.coe_mk, finset.univ_unique,
function.comp_const, finset.sum_singleton] at sum_eq,
convert (b.smul_eq_zero.mp sum_eq).resolve_right x_ne
end
end no_zero_smul_divisors
section singleton
/-- `basis.singleton ι R` is the basis sending the unique element of `ι` to `1 : R`. -/
protected def singleton (ι R : Type*) [unique ι] [semiring R] :
basis ι R R :=
of_repr
{ to_fun := λ x, finsupp.single default x,
inv_fun := λ f, f default,
left_inv := λ x, by simp,
right_inv := λ f, finsupp.unique_ext (by simp),
map_add' := λ x y, by simp,
map_smul' := λ c x, by simp }
@[simp] lemma singleton_apply (ι R : Type*) [unique ι] [semiring R] (i) :
basis.singleton ι R i = 1 :=
apply_eq_iff.mpr (by simp [basis.singleton])
@[simp] lemma singleton_repr (ι R : Type*) [unique ι] [semiring R] (x i) :
(basis.singleton ι R).repr x i = x :=
by simp [basis.singleton, unique.eq_default i]
lemma basis_singleton_iff
{R M : Type*} [ring R] [nontrivial R] [add_comm_group M] [module R M] [no_zero_smul_divisors R M]
(ι : Type*) [unique ι] :
nonempty (basis ι R M) ↔ ∃ x ≠ 0, ∀ y : M, ∃ r : R, r • x = y :=
begin
fsplit,
{ rintro ⟨b⟩,
refine ⟨b default, b.linear_independent.ne_zero _, _⟩,
simpa [span_singleton_eq_top_iff, set.range_unique] using b.span_eq },
{ rintro ⟨x, nz, w⟩,
refine ⟨of_repr $ linear_equiv.symm
{ to_fun := λ f, f default • x,
inv_fun := λ y, finsupp.single default (w y).some,
left_inv := λ f, finsupp.unique_ext _,
right_inv := λ y, _,
map_add' := λ y z, _,
map_smul' := λ c y, _ }⟩,
{ rw [finsupp.add_apply, add_smul] },
{ rw [finsupp.smul_apply, smul_assoc], simp },
{ refine smul_left_injective _ nz _,
simp only [finsupp.single_eq_same],
exact (w (f default • x)).some_spec },
{ simp only [finsupp.single_eq_same],
exact (w y).some_spec } }
end
end singleton
section empty
variables (M)
/-- If `M` is a subsingleton and `ι` is empty, this is the unique `ι`-indexed basis for `M`. -/
protected def empty [subsingleton M] [is_empty ι] : basis ι R M :=
of_repr 0
instance empty_unique [subsingleton M] [is_empty ι] : unique (basis ι R M) :=
{ default := basis.empty M, uniq := λ ⟨x⟩, congr_arg of_repr $ subsingleton.elim _ _ }
end empty
end basis
section fintype
open basis
open fintype
variables [fintype ι] (b : basis ι R M)
/-- A module over `R` with a finite basis is linearly equivalent to functions from its basis to `R`.
-/
def basis.equiv_fun : M ≃ₗ[R] (ι → R) :=
linear_equiv.trans b.repr
({ to_fun := coe_fn,
map_add' := finsupp.coe_add,
map_smul' := finsupp.coe_smul,
..finsupp.equiv_fun_on_finite } : (ι →₀ R) ≃ₗ[R] (ι → R))
/-- A module over a finite ring that admits a finite basis is finite. -/
def module.fintype_of_fintype (b : basis ι R M) [fintype R] : fintype M :=
by haveI := classical.dec_eq ι; exact
fintype.of_equiv _ b.equiv_fun.to_equiv.symm
theorem module.card_fintype (b : basis ι R M) [fintype R] [fintype M] :
card M = (card R) ^ (card ι) :=
by classical; exact
calc card M = card (ι → R) : card_congr b.equiv_fun.to_equiv
... = card R ^ card ι : card_fun
/-- Given a basis `v` indexed by `ι`, the canonical linear equivalence between `ι → R` and `M` maps
a function `x : ι → R` to the linear combination `∑_i x i • v i`. -/
@[simp] lemma basis.equiv_fun_symm_apply (x : ι → R) :
b.equiv_fun.symm x = ∑ i, x i • b i :=
by simp [basis.equiv_fun, finsupp.total_apply, finsupp.sum_fintype]
@[simp]
lemma basis.equiv_fun_apply (u : M) : b.equiv_fun u = b.repr u := rfl
@[simp] lemma basis.map_equiv_fun (f : M ≃ₗ[R] M') :
(b.map f).equiv_fun = f.symm.trans b.equiv_fun :=
rfl
lemma basis.sum_equiv_fun (u : M) : ∑ i, b.equiv_fun u i • b i = u :=
begin
conv_rhs { rw ← b.total_repr u },
simp [finsupp.total_apply, finsupp.sum_fintype, b.equiv_fun_apply]
end
lemma basis.sum_repr (u : M) : ∑ i, b.repr u i • b i = u :=
b.sum_equiv_fun u
@[simp]
lemma basis.equiv_fun_self [decidable_eq ι] (i j : ι) :
b.equiv_fun (b i) j = if i = j then 1 else 0 :=
by { rw [b.equiv_fun_apply, b.repr_self_apply] }
lemma basis.repr_sum_self (c : ι → R) : ⇑(b.repr (∑ i, c i • b i)) = c :=
begin
ext j,
simp only [map_sum, linear_equiv.map_smul, repr_self, finsupp.smul_single, smul_eq_mul,
mul_one, finset.sum_apply'],
rw [finset.sum_eq_single j, finsupp.single_eq_same],
{ rintros i - hi, exact finsupp.single_eq_of_ne hi },
{ intros, have := finset.mem_univ j, contradiction }
end
/-- Define a basis by mapping each vector `x : M` to its coordinates `e x : ι → R`,
as long as `ι` is finite. -/
def basis.of_equiv_fun (e : M ≃ₗ[R] (ι → R)) : basis ι R M :=
basis.of_repr $ e.trans $ linear_equiv.symm $ finsupp.linear_equiv_fun_on_finite R R ι
@[simp] lemma basis.of_equiv_fun_repr_apply (e : M ≃ₗ[R] (ι → R)) (x : M) (i : ι) :
(basis.of_equiv_fun e).repr x i = e x i := rfl
@[simp] lemma basis.coe_of_equiv_fun [decidable_eq ι] (e : M ≃ₗ[R] (ι → R)) :
(basis.of_equiv_fun e : ι → M) = λ i, e.symm (function.update 0 i 1) :=
funext $ λ i, e.injective $ funext $ λ j,
by simp [basis.of_equiv_fun, ←finsupp.single_eq_pi_single, finsupp.single_eq_update]
@[simp] lemma basis.of_equiv_fun_equiv_fun
(v : basis ι R M) : basis.of_equiv_fun v.equiv_fun = v :=
begin
classical,
ext j,
simp only [basis.equiv_fun_symm_apply, basis.coe_of_equiv_fun],
simp_rw [function.update_apply, ite_smul],
simp only [finset.mem_univ, if_true, pi.zero_apply, one_smul, finset.sum_ite_eq', zero_smul],
end
@[simp] lemma basis.equiv_fun_of_equiv_fun (e : M ≃ₗ[R] (ι → R)) :
(basis.of_equiv_fun e).equiv_fun = e :=
begin
ext j,
simp_rw [basis.equiv_fun_apply, basis.of_equiv_fun_repr_apply],
end
variables (S : Type*) [semiring S] [module S M']
variables [smul_comm_class R S M']
@[simp] theorem basis.constr_apply_fintype (f : ι → M') (x : M) :
(b.constr S f : M → M') x = ∑ i, (b.equiv_fun x i) • f i :=
by simp [b.constr_apply, b.equiv_fun_apply, finsupp.sum_fintype]
/-- If the submodule `P` has a finite basis,
`x ∈ P` iff it is a linear combination of basis vectors. -/
lemma basis.mem_submodule_iff' {P : submodule R M} (b : basis ι R P) {x : M} :
x ∈ P ↔ ∃ (c : ι → R), x = ∑ i, c i • b i :=
b.mem_submodule_iff.trans $ finsupp.equiv_fun_on_finite.exists_congr_left.trans $ exists_congr $
λ c, by simp [finsupp.sum_fintype]
lemma basis.coord_equiv_fun_symm (i : ι) (f : ι → R) : b.coord i (b.equiv_fun.symm f) = f i :=
b.coord_repr_symm i (finsupp.equiv_fun_on_finite.symm f)
end fintype
end module
section comm_semiring
namespace basis
variables [comm_semiring R]
variables [add_comm_monoid M] [module R M] [add_comm_monoid M'] [module R M']
variables (b : basis ι R M) (b' : basis ι' R M')
/-- If `b` is a basis for `M` and `b'` a basis for `M'`,
and `f`, `g` form a bijection between the basis vectors,
`b.equiv' b' f g hf hg hgf hfg` is a linear equivalence `M ≃ₗ[R] M'`, mapping `b i` to `f (b i)`.
-/
def equiv' (f : M → M') (g : M' → M)
(hf : ∀ i, f (b i) ∈ range b') (hg : ∀ i, g (b' i) ∈ range b)
(hgf : ∀i, g (f (b i)) = b i) (hfg : ∀i, f (g (b' i)) = b' i) :
M ≃ₗ[R] M' :=
{ inv_fun := b'.constr R (g ∘ b'),
left_inv :=
have (b'.constr R (g ∘ b')).comp (b.constr R (f ∘ b)) = linear_map.id,
from (b.ext $ λ i, exists.elim (hf i)
(λ i' hi', by rw [linear_map.comp_apply, b.constr_basis, function.comp_apply, ← hi',
b'.constr_basis, function.comp_apply, hi', hgf, linear_map.id_apply])),
λ x, congr_arg (λ (h : M →ₗ[R] M), h x) this,
right_inv :=
have (b.constr R (f ∘ b)).comp (b'.constr R (g ∘ b')) = linear_map.id,
from (b'.ext $ λ i, exists.elim (hg i)
(λ i' hi', by rw [linear_map.comp_apply, b'.constr_basis, function.comp_apply, ← hi',
b.constr_basis, function.comp_apply, hi', hfg, linear_map.id_apply])),
λ x, congr_arg (λ (h : M' →ₗ[R] M'), h x) this,
.. b.constr R (f ∘ b) }
@[simp] lemma equiv'_apply (f : M → M') (g : M' → M) (hf hg hgf hfg) (i : ι) :
b.equiv' b' f g hf hg hgf hfg (b i) = f (b i) :=
b.constr_basis R _ _
@[simp] lemma equiv'_symm_apply (f : M → M') (g : M' → M) (hf hg hgf hfg) (i : ι') :
(b.equiv' b' f g hf hg hgf hfg).symm (b' i) = g (b' i) :=
b'.constr_basis R _ _
lemma sum_repr_mul_repr {ι'} [fintype ι'] (b' : basis ι' R M) (x : M) (i : ι) :
∑ (j : ι'), b.repr (b' j) i * b'.repr x j = b.repr x i :=
begin
conv_rhs { rw [← b'.sum_repr x] },
simp_rw [linear_equiv.map_sum, linear_equiv.map_smul, finset.sum_apply'],
refine finset.sum_congr rfl (λ j _, _),
rw [finsupp.smul_apply, smul_eq_mul, mul_comm]
end
end basis
end comm_semiring
section module
open linear_map
variables {v : ι → M}
variables [ring R] [comm_ring R₂] [add_comm_group M] [add_comm_group M'] [add_comm_group M'']
variables [module R M] [module R₂ M] [module R M'] [module R M'']
variables {c d : R} {x y : M}
variables (b : basis ι R M)
namespace basis
/--
Any basis is a maximal linear independent set.
-/
lemma maximal [nontrivial R] (b : basis ι R M) : b.linear_independent.maximal :=
λ w hi h,
begin
-- If `range w` is strictly bigger than `range b`,
apply le_antisymm h,
-- then choose some `x ∈ range w \ range b`,
intros x p,
by_contradiction q,
-- and write it in terms of the basis.
have e := b.total_repr x,
-- This then expresses `x` as a linear combination
-- of elements of `w` which are in the range of `b`,
let u : ι ↪ w := ⟨λ i, ⟨b i, h ⟨i, rfl⟩⟩, λ i i' r,
b.injective (by simpa only [subtype.mk_eq_mk] using r)⟩,
have r : ∀ i, b i = u i := λ i, rfl,
simp_rw [finsupp.total_apply, r] at e,
change (b.repr x).sum (λ (i : ι) (a : R), (λ (x : w) (r : R), r • (x : M)) (u i) a) =
((⟨x, p⟩ : w) : M) at e,
rw [←finsupp.sum_emb_domain, ←finsupp.total_apply] at e,
-- Now we can contradict the linear independence of `hi`
refine hi.total_ne_of_not_mem_support _ _ e,
simp only [finset.mem_map, finsupp.support_emb_domain],
rintro ⟨j, -, W⟩,
simp only [embedding.coe_fn_mk, subtype.mk_eq_mk, ←r] at W,
apply q ⟨j, W⟩,
end
section mk
variables (hli : linear_independent R v) (hsp : ⊤ ≤ span R (range v))
/-- A linear independent family of vectors spanning the whole module is a basis. -/
protected noncomputable def mk : basis ι R M :=
basis.of_repr
{ inv_fun := finsupp.total _ _ _ v,
left_inv := λ x, hli.total_repr ⟨x, _⟩,
right_inv := λ x, hli.repr_eq rfl,
.. hli.repr.comp (linear_map.id.cod_restrict _ (λ h, hsp submodule.mem_top)) }
@[simp] lemma mk_repr :
(basis.mk hli hsp).repr x = hli.repr ⟨x, hsp submodule.mem_top⟩ :=
rfl
lemma mk_apply (i : ι) : basis.mk hli hsp i = v i :=
show finsupp.total _ _ _ v _ = v i, by simp
@[simp] lemma coe_mk : ⇑(basis.mk hli hsp) = v :=
funext (mk_apply _ _)
variables {hli hsp}
/-- Given a basis, the `i`th element of the dual basis evaluates to 1 on the `i`th element of the
basis. -/
lemma mk_coord_apply_eq (i : ι) :
(basis.mk hli hsp).coord i (v i) = 1 :=
show hli.repr ⟨v i, submodule.subset_span (mem_range_self i)⟩ i = 1,
by simp [hli.repr_eq_single i]
/-- Given a basis, the `i`th element of the dual basis evaluates to 0 on the `j`th element of the
basis if `j ≠ i`. -/
lemma mk_coord_apply_ne {i j : ι} (h : j ≠ i) :
(basis.mk hli hsp).coord i (v j) = 0 :=
show hli.repr ⟨v j, submodule.subset_span (mem_range_self j)⟩ i = 0,
by simp [hli.repr_eq_single j, h]
/-- Given a basis, the `i`th element of the dual basis evaluates to the Kronecker delta on the
`j`th element of the basis. -/
lemma mk_coord_apply [decidable_eq ι] {i j : ι} :
(basis.mk hli hsp).coord i (v j) = if j = i then 1 else 0 :=
begin
cases eq_or_ne j i,
{ simp only [h, if_true, eq_self_iff_true, mk_coord_apply_eq i], },
{ simp only [h, if_false, mk_coord_apply_ne h], },
end
end mk
section span
variables (hli : linear_independent R v)
/-- A linear independent family of vectors is a basis for their span. -/
protected noncomputable def span : basis ι R (span R (range v)) :=
basis.mk (linear_independent_span hli) $
begin
intros x _,
have h₁ : (coe : span R (range v) → M) '' set.range (λ i, subtype.mk (v i) _) = range v,
{ rw ← set.range_comp,
refl },
have h₂ : map (submodule.subtype (span R (range v)))
(span R (set.range (λ i, subtype.mk (v i) _))) = span R (range v),
{ rw [← span_image, submodule.coe_subtype, h₁] },
have h₃ : (x : M) ∈ map (submodule.subtype (span R (range v)))
(span R (set.range (λ i, subtype.mk (v i) _))),
{ rw h₂, apply subtype.mem x },
rcases mem_map.1 h₃ with ⟨y, hy₁, hy₂⟩,
have h_x_eq_y : x = y,
{ rw [subtype.ext_iff, ← hy₂], simp },
rwa h_x_eq_y
end
protected lemma span_apply (i : ι) : (basis.span hli i : M) = v i :=
congr_arg (coe : span R (range v) → M) $ basis.mk_apply (linear_independent_span hli) _ i
end span
lemma group_smul_span_eq_top
{G : Type*} [group G] [distrib_mul_action G R] [distrib_mul_action G M]
[is_scalar_tower G R M] {v : ι → M} (hv : submodule.span R (set.range v) = ⊤) {w : ι → G} :
submodule.span R (set.range (w • v)) = ⊤ :=
begin
rw eq_top_iff,
intros j hj,
rw ← hv at hj,
rw submodule.mem_span at hj ⊢,
refine λ p hp, hj p (λ u hu, _),
obtain ⟨i, rfl⟩ := hu,
have : ((w i)⁻¹ • 1 : R) • w i • v i ∈ p := p.smul_mem ((w i)⁻¹ • 1 : R) (hp ⟨i, rfl⟩),
rwa [smul_one_smul, inv_smul_smul] at this,
end
/-- Given a basis `v` and a map `w` such that for all `i`, `w i` are elements of a group,
`group_smul` provides the basis corresponding to `w • v`. -/
def group_smul {G : Type*} [group G] [distrib_mul_action G R] [distrib_mul_action G M]
[is_scalar_tower G R M] [smul_comm_class G R M] (v : basis ι R M) (w : ι → G) :
basis ι R M :=
@basis.mk ι R M (w • v) _ _ _
(v.linear_independent.group_smul w) (group_smul_span_eq_top v.span_eq).ge
lemma group_smul_apply {G : Type*} [group G] [distrib_mul_action G R] [distrib_mul_action G M]
[is_scalar_tower G R M] [smul_comm_class G R M] {v : basis ι R M} {w : ι → G} (i : ι) :
v.group_smul w i = (w • v : ι → M) i :=
mk_apply
(v.linear_independent.group_smul w) (group_smul_span_eq_top v.span_eq).ge i
lemma units_smul_span_eq_top {v : ι → M} (hv : submodule.span R (set.range v) = ⊤)
{w : ι → Rˣ} : submodule.span R (set.range (w • v)) = ⊤ :=
group_smul_span_eq_top hv
/-- Given a basis `v` and a map `w` such that for all `i`, `w i` is a unit, `smul_of_is_unit`
provides the basis corresponding to `w • v`. -/
def units_smul (v : basis ι R M) (w : ι → Rˣ) :
basis ι R M :=
@basis.mk ι R M (w • v) _ _ _
(v.linear_independent.units_smul w) (units_smul_span_eq_top v.span_eq).ge
lemma units_smul_apply {v : basis ι R M} {w : ι → Rˣ} (i : ι) :
v.units_smul w i = w i • v i :=
mk_apply
(v.linear_independent.units_smul w) (units_smul_span_eq_top v.span_eq).ge i
@[simp] lemma coord_units_smul (e : basis ι R₂ M) (w : ι → R₂ˣ) (i : ι) :
(e.units_smul w).coord i = (w i)⁻¹ • e.coord i :=
begin
classical,
apply e.ext,
intros j,
transitivity ((e.units_smul w).coord i) ((w j)⁻¹ • (e.units_smul w) j),
{ congr,
simp [basis.units_smul, ← mul_smul], },
simp only [basis.coord_apply, linear_map.smul_apply, basis.repr_self, units.smul_def,
smul_hom_class.map_smul, finsupp.single_apply],
split_ifs with h h,
{ simp [h] },
{ simp }
end
@[simp] lemma repr_units_smul (e : basis ι R₂ M) (w : ι → R₂ˣ) (v : M) (i : ι) :
(e.units_smul w).repr v i = (w i)⁻¹ • e.repr v i :=
congr_arg (λ f : M →ₗ[R₂] R₂, f v) (e.coord_units_smul w i)
/-- A version of `smul_of_units` that uses `is_unit`. -/
def is_unit_smul (v : basis ι R M) {w : ι → R} (hw : ∀ i, is_unit (w i)):
basis ι R M :=
units_smul v (λ i, (hw i).unit)
lemma is_unit_smul_apply {v : basis ι R M} {w : ι → R} (hw : ∀ i, is_unit (w i)) (i : ι) :
v.is_unit_smul hw i = w i • v i :=
units_smul_apply i
section fin
/-- Let `b` be a basis for a submodule `N` of `M`. If `y : M` is linear independent of `N`
and `y` and `N` together span the whole of `M`, then there is a basis for `M`
whose basis vectors are given by `fin.cons y b`. -/
noncomputable def mk_fin_cons {n : ℕ} {N : submodule R M} (y : M) (b : basis (fin n) R N)
(hli : ∀ (c : R) (x ∈ N), c • y + x = 0 → c = 0)
(hsp : ∀ (z : M), ∃ (c : R), z + c • y ∈ N) :
basis (fin (n + 1)) R M :=
have span_b : submodule.span R (set.range (N.subtype ∘ b)) = N,
{ rw [set.range_comp, submodule.span_image, b.span_eq, submodule.map_subtype_top] },
@basis.mk _ _ _ (fin.cons y (N.subtype ∘ b) : fin (n + 1) → M) _ _ _
((b.linear_independent.map' N.subtype (submodule.ker_subtype _)) .fin_cons' _ _ $
by { rintros c ⟨x, hx⟩ hc, rw span_b at hx, exact hli c x hx hc })
(λ x _, by { rw [fin.range_cons, submodule.mem_span_insert', span_b], exact hsp x })
@[simp] lemma coe_mk_fin_cons {n : ℕ} {N : submodule R M} (y : M) (b : basis (fin n) R N)
(hli : ∀ (c : R) (x ∈ N), c • y + x = 0 → c = 0)
(hsp : ∀ (z : M), ∃ (c : R), z + c • y ∈ N) :
(mk_fin_cons y b hli hsp : fin (n + 1) → M) = fin.cons y (coe ∘ b) :=
coe_mk _ _
/-- Let `b` be a basis for a submodule `N ≤ O`. If `y ∈ O` is linear independent of `N`
and `y` and `N` together span the whole of `O`, then there is a basis for `O`
whose basis vectors are given by `fin.cons y b`. -/
noncomputable def mk_fin_cons_of_le {n : ℕ} {N O : submodule R M}
(y : M) (yO : y ∈ O) (b : basis (fin n) R N) (hNO : N ≤ O)
(hli : ∀ (c : R) (x ∈ N), c • y + x = 0 → c = 0)
(hsp : ∀ (z ∈ O), ∃ (c : R), z + c • y ∈ N) :
basis (fin (n + 1)) R O :=
mk_fin_cons ⟨y, yO⟩ (b.map (submodule.comap_subtype_equiv_of_le hNO).symm)
(λ c x hc hx, hli c x (submodule.mem_comap.mp hc) (congr_arg coe hx))
(λ z, hsp z z.2)
@[simp] lemma coe_mk_fin_cons_of_le {n : ℕ} {N O : submodule R M}
(y : M) (yO : y ∈ O) (b : basis (fin n) R N) (hNO : N ≤ O)
(hli : ∀ (c : R) (x ∈ N), c • y + x = 0 → c = 0)
(hsp : ∀ (z ∈ O), ∃ (c : R), z + c • y ∈ N) :
(mk_fin_cons_of_le y yO b hNO hli hsp : fin (n + 1) → O) =
fin.cons ⟨y, yO⟩ (submodule.of_le hNO ∘ b) :=
coe_mk_fin_cons _ _ _ _
/-- The basis of `R × R` given by the two vectors `(1, 0)` and `(0, 1)`. -/
protected def fin_two_prod (R : Type*) [semiring R] : basis (fin 2) R (R × R) :=
basis.of_equiv_fun (linear_equiv.fin_two_arrow R R).symm
@[simp] lemma fin_two_prod_zero (R : Type*) [semiring R] : basis.fin_two_prod R 0 = (1, 0) :=
by simp [basis.fin_two_prod]
@[simp] lemma fin_two_prod_one (R : Type*) [semiring R] : basis.fin_two_prod R 1 = (0, 1) :=
by simp [basis.fin_two_prod]
@[simp] lemma coe_fin_two_prod_repr {R : Type*} [semiring R] (x : R × R) :
⇑((basis.fin_two_prod R).repr x) = ![x.fst, x.snd] :=
rfl
end fin
end basis
end module
section induction
variables [ring R] [is_domain R]
variables [add_comm_group M] [module R M] {b : ι → M}
/-- If `N` is a submodule with finite rank, do induction on adjoining a linear independent
element to a submodule. -/
def submodule.induction_on_rank_aux (b : basis ι R M) (P : submodule R M → Sort*)
(ih : ∀ (N : submodule R M),
(∀ (N' ≤ N) (x ∈ N), (∀ (c : R) (y ∈ N'), c • x + y = (0 : M) → c = 0) → P N') → P N)
(n : ℕ) (N : submodule R M)
(rank_le : ∀ {m : ℕ} (v : fin m → N),
linear_independent R (coe ∘ v : fin m → M) → m ≤ n) :
P N :=
begin
haveI : decidable_eq M := classical.dec_eq M,
have Pbot : P ⊥,
{ apply ih,
intros N N_le x x_mem x_ortho,
exfalso,
simpa using x_ortho 1 0 N.zero_mem },
induction n with n rank_ih generalizing N,
{ suffices : N = ⊥,
{ rwa this },
apply eq_bot_of_rank_eq_zero b _ (λ m v hv, le_zero_iff.mp (rank_le v hv)) },
apply ih,
intros N' N'_le x x_mem x_ortho,
apply rank_ih,
intros m v hli,
refine nat.succ_le_succ_iff.mp (rank_le (fin.cons ⟨x, x_mem⟩ (λ i, ⟨v i, N'_le (v i).2⟩)) _),
convert hli.fin_cons' x _ _,
{ ext i, refine fin.cases _ _ i; simp },
{ intros c y hcy,
refine x_ortho c y (submodule.span_le.mpr _ y.2) hcy,
rintros _ ⟨z, rfl⟩,
exact (v z).2 }
end
end induction
section division_ring
variables [division_ring K] [add_comm_group V] [add_comm_group V'] [module K V] [module K V']
variables {v : ι → V} {s t : set V} {x y z : V}
include K
open submodule
namespace basis
section exists_basis
/-- If `s` is a linear independent set of vectors, we can extend it to a basis. -/
noncomputable def extend (hs : linear_independent K (coe : s → V)) :
basis _ K V :=
basis.mk
(@linear_independent.restrict_of_comp_subtype _ _ _ id _ _ _ _ (hs.linear_independent_extend _))
(set_like.coe_subset_coe.mp $ by simpa using hs.subset_span_extend (subset_univ s))
lemma extend_apply_self (hs : linear_independent K (coe : s → V))
(x : hs.extend _) :
basis.extend hs x = x :=
basis.mk_apply _ _ _
@[simp] lemma coe_extend (hs : linear_independent K (coe : s → V)) :
⇑(basis.extend hs) = coe :=
funext (extend_apply_self hs)
lemma range_extend (hs : linear_independent K (coe : s → V)) :
range (basis.extend hs) = hs.extend (subset_univ _) :=
by rw [coe_extend, subtype.range_coe_subtype, set_of_mem_eq]
/-- If `v` is a linear independent family of vectors, extend it to a basis indexed by a sum type. -/
noncomputable def sum_extend (hs : linear_independent K v) :
basis (ι ⊕ _) K V :=
let s := set.range v,
e : ι ≃ s := equiv.of_injective v hs.injective,
b := hs.to_subtype_range.extend (subset_univ (set.range v)) in
(basis.extend hs.to_subtype_range).reindex $ equiv.symm $
calc ι ⊕ (b \ s : set V) ≃ s ⊕ (b \ s : set V) : equiv.sum_congr e (equiv.refl _)
... ≃ b :
by haveI := classical.dec_pred (∈ s); exact
equiv.set.sum_diff_subset (hs.to_subtype_range.subset_extend _)
lemma subset_extend {s : set V} (hs : linear_independent K (coe : s → V)) :
s ⊆ hs.extend (set.subset_univ _) :=
hs.subset_extend _
section
variables (K V)
/-- A set used to index `basis.of_vector_space`. -/
noncomputable def of_vector_space_index : set V :=
(linear_independent_empty K V).extend (subset_univ _)
/-- Each vector space has a basis. -/
noncomputable def of_vector_space : basis (of_vector_space_index K V) K V :=
basis.extend (linear_independent_empty K V)
lemma of_vector_space_apply_self (x : of_vector_space_index K V) :
of_vector_space K V x = x :=
basis.mk_apply _ _ _
@[simp] lemma coe_of_vector_space :
⇑(of_vector_space K V) = coe :=
funext (λ x, of_vector_space_apply_self K V x)
lemma of_vector_space_index.linear_independent :
linear_independent K (coe : of_vector_space_index K V → V) :=
by { convert (of_vector_space K V).linear_independent, ext x, rw of_vector_space_apply_self }
lemma range_of_vector_space :
range (of_vector_space K V) = of_vector_space_index K V :=
range_extend _
lemma exists_basis : ∃ s : set V, nonempty (basis s K V) :=
⟨of_vector_space_index K V, ⟨of_vector_space K V⟩⟩
end
end exists_basis
end basis
open fintype
variables (K V)
theorem vector_space.card_fintype [fintype K] [fintype V] :
∃ n : ℕ, card V = (card K) ^ n :=
by classical; exact
⟨card (basis.of_vector_space_index K V), module.card_fintype (basis.of_vector_space K V)⟩
section atoms_of_submodule_lattice
variables {K V}
/-- For a module over a division ring, the span of a nonzero element is an atom of the
lattice of submodules. -/
lemma nonzero_span_atom (v : V) (hv : v ≠ 0) : is_atom (span K {v} : submodule K V) :=
begin
split,
{ rw submodule.ne_bot_iff, exact ⟨v, ⟨mem_span_singleton_self v, hv⟩⟩ },
{ intros T hT, by_contra, apply hT.2,
change (span K {v}) ≤ T,
simp_rw [span_singleton_le_iff_mem, ← ne.def, submodule.ne_bot_iff] at *,
rcases h with ⟨s, ⟨hs, hz⟩⟩,
cases (mem_span_singleton.1 (hT.1 hs)) with a ha,
have h : a ≠ 0, by { intro h, rw [h, zero_smul] at ha, exact hz ha.symm },
apply_fun (λ x, a⁻¹ • x) at ha,
simp_rw [← mul_smul, inv_mul_cancel h, one_smul, ha] at *, exact smul_mem T _ hs},
end
/-- The atoms of the lattice of submodules of a module over a division ring are the
submodules equal to the span of a nonzero element of the module. -/
lemma atom_iff_nonzero_span (W : submodule K V) :
is_atom W ↔ ∃ (v : V) (hv : v ≠ 0), W = span K {v} :=
begin
refine ⟨λ h, _, λ h, _ ⟩,
{ cases h with hbot h,
rcases ((submodule.ne_bot_iff W).1 hbot) with ⟨v, ⟨hW, hv⟩⟩,
refine ⟨v, ⟨hv, _⟩⟩,
by_contra heq,
specialize h (span K {v}),
rw [span_singleton_eq_bot, lt_iff_le_and_ne] at h,
exact hv (h ⟨(span_singleton_le_iff_mem v W).2 hW, ne.symm heq⟩) },
{ rcases h with ⟨v, ⟨hv, rfl⟩⟩, exact nonzero_span_atom v hv },
end
/-- The lattice of submodules of a module over a division ring is atomistic. -/
instance : is_atomistic (submodule K V) :=
{ eq_Sup_atoms :=
begin
intro W,
use {T : submodule K V | ∃ (v : V) (hv : v ∈ W) (hz : v ≠ 0), T = span K {v}},
refine ⟨submodule_eq_Sup_le_nonzero_spans W, _⟩,
rintros _ ⟨w, ⟨_, ⟨hw, rfl⟩⟩⟩, exact nonzero_span_atom w hw
end }
end atoms_of_submodule_lattice
variables {K V}
lemma linear_map.exists_left_inverse_of_injective (f : V →ₗ[K] V')
(hf_inj : f.ker = ⊥) : ∃g:V' →ₗ[K] V, g.comp f = linear_map.id :=
begin
let B := basis.of_vector_space_index K V,
let hB := basis.of_vector_space K V,
have hB₀ : _ := hB.linear_independent.to_subtype_range,
have : linear_independent K (λ x, x : f '' B → V'),
{ have h₁ : linear_independent K (λ (x : ↥(⇑f '' range (basis.of_vector_space _ _))), ↑x) :=
@linear_independent.image_subtype _ _ _ _ _ _ _ _ _ f hB₀
(show disjoint _ _, by simp [hf_inj]),
rwa [basis.range_of_vector_space K V] at h₁ },
let C := this.extend (subset_univ _),
have BC := this.subset_extend (subset_univ _),
let hC := basis.extend this,
haveI : inhabited V := ⟨0⟩,
refine ⟨hC.constr ℕ (C.restrict (inv_fun f)), hB.ext (λ b, _)⟩,
rw image_subset_iff at BC,
have fb_eq : f b = hC ⟨f b, BC b.2⟩,
{ change f b = basis.extend this _,
rw [basis.extend_apply_self, subtype.coe_mk] },
dsimp [hB],
rw [basis.of_vector_space_apply_self, fb_eq, hC.constr_basis],
exact left_inverse_inv_fun (linear_map.ker_eq_bot.1 hf_inj) _
end
lemma submodule.exists_is_compl (p : submodule K V) : ∃ q : submodule K V, is_compl p q :=
let ⟨f, hf⟩ := p.subtype.exists_left_inverse_of_injective p.ker_subtype in
⟨f.ker, linear_map.is_compl_of_proj $ linear_map.ext_iff.1 hf⟩
instance module.submodule.complemented_lattice : complemented_lattice (submodule K V) :=
⟨submodule.exists_is_compl⟩
lemma linear_map.exists_right_inverse_of_surjective (f : V →ₗ[K] V')
(hf_surj : f.range = ⊤) : ∃g:V' →ₗ[K] V, f.comp g = linear_map.id :=
begin
let C := basis.of_vector_space_index K V',
let hC := basis.of_vector_space K V',
haveI : inhabited V := ⟨0⟩,
use hC.constr ℕ (C.restrict (inv_fun f)),
refine hC.ext (λ c, _),
rw [linear_map.comp_apply, hC.constr_basis],
simp [right_inverse_inv_fun (linear_map.range_eq_top.1 hf_surj) c]
end
/-- Any linear map `f : p →ₗ[K] V'` defined on a subspace `p` can be extended to the whole
space. -/
lemma linear_map.exists_extend {p : submodule K V} (f : p →ₗ[K] V') :
∃ g : V →ₗ[K] V', g.comp p.subtype = f :=
let ⟨g, hg⟩ := p.subtype.exists_left_inverse_of_injective p.ker_subtype in
⟨f.comp g, by rw [linear_map.comp_assoc, hg, f.comp_id]⟩
open submodule linear_map
/-- If `p < ⊤` is a subspace of a vector space `V`, then there exists a nonzero linear map
`f : V →ₗ[K] K` such that `p ≤ ker f`. -/
lemma submodule.exists_le_ker_of_lt_top (p : submodule K V) (hp : p < ⊤) :
∃ f ≠ (0 : V →ₗ[K] K), p ≤ ker f :=
begin
rcases set_like.exists_of_lt hp with ⟨v, -, hpv⟩, clear hp,
rcases (linear_pmap.sup_span_singleton ⟨p, 0⟩ v (1 : K) hpv).to_fun.exists_extend with ⟨f, hf⟩,
refine ⟨f, _, _⟩,
{ rintro rfl, rw [linear_map.zero_comp] at hf,
have := linear_pmap.sup_span_singleton_apply_mk ⟨p, 0⟩ v (1 : K) hpv 0 p.zero_mem 1,
simpa using (linear_map.congr_fun hf _).trans this },
{ refine λ x hx, mem_ker.2 _,
have := linear_pmap.sup_span_singleton_apply_mk ⟨p, 0⟩ v (1 : K) hpv x hx 0,
simpa using (linear_map.congr_fun hf _).trans this }
end
theorem quotient_prod_linear_equiv (p : submodule K V) :
nonempty (((V ⧸ p) × p) ≃ₗ[K] V) :=
let ⟨q, hq⟩ := p.exists_is_compl in nonempty.intro $
((quotient_equiv_of_is_compl p q hq).prod (linear_equiv.refl _ _)).trans
(prod_equiv_of_is_compl q p hq.symm)
end division_ring
section restrict_scalars
variables {S : Type*} [comm_ring R] [ring S] [nontrivial S] [add_comm_group M]
variables [algebra R S] [module S M] [module R M]
variables [is_scalar_tower R S M] [no_zero_smul_divisors R S] (b : basis ι S M)
variables (R)
open submodule
/-- Let `b` be a `S`-basis of `M`. Let `R` be a comm_ring such that `algebra R S` with no zero
smul divisors, then the submodule of `M` spanned by `b` over `R` admits `b` as a `R`-basis. -/
noncomputable def basis.restrict_scalars : basis ι R (span R (set.range b)) :=
basis.span (b.linear_independent.restrict_scalars (smul_left_injective R one_ne_zero))
@[simp]
lemma basis.restrict_scalars_apply (i : ι) : (b.restrict_scalars R i : M) = b i :=
by simp only [basis.restrict_scalars, basis.span_apply]
@[simp]
lemma basis.restrict_scalars_repr_apply (m : span R (set.range b)) (i : ι) :
algebra_map R S ((b.restrict_scalars R).repr m i) = b.repr m i :=
begin
suffices : finsupp.map_range.linear_map (algebra.linear_map R S) ∘ₗ
(b.restrict_scalars R).repr.to_linear_map
= ((b.repr : M →ₗ[S] (ι →₀ S)).restrict_scalars R).dom_restrict _,
{ exact finsupp.congr_fun (linear_map.congr_fun this m) i, },
refine basis.ext (b.restrict_scalars R) (λ _, _),
simp only [linear_map.coe_comp, linear_equiv.coe_to_linear_map, function.comp_app, map_one,
basis.repr_self, finsupp.map_range.linear_map_apply, finsupp.map_range_single,
algebra.linear_map_apply, linear_map.dom_restrict_apply, linear_equiv.coe_coe,
basis.restrict_scalars_apply, linear_map.coe_restrict_scalars_eq_coe],
end
/-- Let `b` be a `S`-basis of `M`. Then `m : M` lies in the `R`-module spanned by `b` iff all the
coordinates of `m` on the basis `b` are in `R` (see `basis.mem_span` for the case `R = S`). -/
lemma basis.mem_span_iff_repr_mem (m : M) :
m ∈ span R (set.range b) ↔ ∀ i, b.repr m i ∈ set.range (algebra_map R S) :=
begin
refine ⟨λ hm i, ⟨(b.restrict_scalars R).repr ⟨m, hm⟩ i,
(b.restrict_scalars_repr_apply R ⟨m, hm⟩ i)⟩, λ h, _⟩,
rw [← b.total_repr m, finsupp.total_apply S _],
refine sum_mem (λ i _, _),
obtain ⟨_, h⟩ := h i,
simp_rw [← h, algebra_map_smul],
exact smul_mem _ _ (subset_span (set.mem_range_self i)),
end
end restrict_scalars
|
2cc7b4f291e917315f180b8b8ff813c37e69d654 | 6dc0c8ce7a76229dd81e73ed4474f15f88a9e294 | /stage0/src/Std/Data/HashSet.lean | a57adbea912c6ee5cb854479bcf8d97e0cc0aef6 | [
"Apache-2.0"
] | permissive | williamdemeo/lean4 | 72161c58fe65c3ad955d6a3050bb7d37c04c0d54 | 6d00fcf1d6d873e195f9220c668ef9c58e9c4a35 | refs/heads/master | 1,678,305,356,877 | 1,614,708,995,000 | 1,614,708,995,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 6,069 | lean | /-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
-/
namespace Std
universes u v w
def HashSetBucket (α : Type u) :=
{ b : Array (List α) // b.size > 0 }
def HashSetBucket.update {α : Type u} (data : HashSetBucket α) (i : USize) (d : List α) (h : i.toNat < data.val.size) : HashSetBucket α :=
⟨ data.val.uset i d h,
by erw [Array.size_set]; exact data.property ⟩
structure HashSetImp (α : Type u) where
size : Nat
buckets : HashSetBucket α
def mkHashSetImp {α : Type u} (nbuckets := 8) : HashSetImp α :=
let n := if nbuckets = 0 then 8 else nbuckets
{ size := 0,
buckets :=
⟨ mkArray n [],
by rw [Array.size_mkArray]; cases nbuckets; decide!; apply Nat.zeroLtSucc ⟩ }
namespace HashSetImp
variable {α : Type u}
def mkIdx {n : Nat} (h : n > 0) (u : USize) : { u : USize // u.toNat < n } :=
⟨u % n, USize.modnLt _ h⟩
@[inline] def reinsertAux (hashFn : α → USize) (data : HashSetBucket α) (a : α) : HashSetBucket α :=
let ⟨i, h⟩ := mkIdx data.property (hashFn a)
data.update i (a :: data.val.uget i h) h
@[inline] def foldBucketsM {δ : Type w} {m : Type w → Type w} [Monad m] (data : HashSetBucket α) (d : δ) (f : δ → α → m δ) : m δ :=
data.val.foldlM (init := d) fun d as => as.foldlM f d
@[inline] def foldBuckets {δ : Type w} (data : HashSetBucket α) (d : δ) (f : δ → α → δ) : δ :=
Id.run $ foldBucketsM data d f
@[inline] def foldM {δ : Type w} {m : Type w → Type w} [Monad m] (f : δ → α → m δ) (d : δ) (h : HashSetImp α) : m δ :=
foldBucketsM h.buckets d f
@[inline] def fold {δ : Type w} (f : δ → α → δ) (d : δ) (m : HashSetImp α) : δ :=
foldBuckets m.buckets d f
def find? [BEq α] [Hashable α] (m : HashSetImp α) (a : α) : Option α :=
match m with
| ⟨_, buckets⟩ =>
let ⟨i, h⟩ := mkIdx buckets.property (hash a)
(buckets.val.uget i h).find? (fun a' => a == a')
def contains [BEq α] [Hashable α] (m : HashSetImp α) (a : α) : Bool :=
match m with
| ⟨_, buckets⟩ =>
let ⟨i, h⟩ := mkIdx buckets.property (hash a)
(buckets.val.uget i h).contains a
-- TODO: remove `partial` by using well-founded recursion
partial def moveEntries [Hashable α] (i : Nat) (source : Array (List α)) (target : HashSetBucket α) : HashSetBucket α :=
if h : i < source.size then
let idx : Fin source.size := ⟨i, h⟩
let es : List α := source.get idx
-- We remove `es` from `source` to make sure we can reuse its memory cells when performing es.foldl
let source := source.set idx []
let target := es.foldl (reinsertAux hash) target
moveEntries (i+1) source target
else target
def expand [Hashable α] (size : Nat) (buckets : HashSetBucket α) : HashSetImp α :=
let nbuckets := buckets.val.size * 2
have nbuckets > 0 from Nat.mulPos buckets.property (decide! : 2 > 0)
let new_buckets : HashSetBucket α := ⟨mkArray nbuckets [], by rw [Array.size_mkArray]; assumption⟩
{ size := size,
buckets := moveEntries 0 buckets.val new_buckets }
def insert [BEq α] [Hashable α] (m : HashSetImp α) (a : α) : HashSetImp α :=
match m with
| ⟨size, buckets⟩ =>
let ⟨i, h⟩ := mkIdx buckets.property (hash a)
let bkt := buckets.val.uget i h
if bkt.contains a
then ⟨size, buckets.update i (bkt.replace a a) h⟩
else
let size' := size + 1
let buckets' := buckets.update i (a :: bkt) h
if size' ≤ buckets.val.size
then { size := size', buckets := buckets' }
else expand size' buckets'
def erase [BEq α] [Hashable α] (m : HashSetImp α) (a : α) : HashSetImp α :=
match m with
| ⟨ size, buckets ⟩ =>
let ⟨i, h⟩ := mkIdx buckets.property (hash a)
let bkt := buckets.val.uget i h
if bkt.contains a then ⟨size - 1, buckets.update i (bkt.erase a) h⟩
else m
inductive WellFormed [BEq α] [Hashable α] : HashSetImp α → Prop where
| mkWff : ∀ n, WellFormed (mkHashSetImp n)
| insertWff : ∀ m a, WellFormed m → WellFormed (insert m a)
| eraseWff : ∀ m a, WellFormed m → WellFormed (erase m a)
end HashSetImp
def HashSet (α : Type u) [BEq α] [Hashable α] :=
{ m : HashSetImp α // m.WellFormed }
open HashSetImp
def mkHashSet {α : Type u} [BEq α] [Hashable α] (nbuckets := 8) : HashSet α :=
⟨ mkHashSetImp nbuckets, WellFormed.mkWff nbuckets ⟩
namespace HashSet
variable {α : Type u} [BEq α] [Hashable α]
instance : Inhabited (HashSet α) where
default := mkHashSet
instance : EmptyCollection (HashSet α) := ⟨mkHashSet⟩
@[inline] def insert (m : HashSet α) (a : α) : HashSet α :=
match m with
| ⟨ m, hw ⟩ => ⟨ m.insert a, WellFormed.insertWff m a hw ⟩
@[inline] def erase (m : HashSet α) (a : α) : HashSet α :=
match m with
| ⟨ m, hw ⟩ => ⟨ m.erase a, WellFormed.eraseWff m a hw ⟩
@[inline] def find? (m : HashSet α) (a : α) : Option α :=
match m with
| ⟨ m, _ ⟩ => m.find? a
@[inline] def contains (m : HashSet α) (a : α) : Bool :=
match m with
| ⟨ m, _ ⟩ => m.contains a
@[inline] def foldM {δ : Type w} {m : Type w → Type w} [Monad m] (f : δ → α → m δ) (init : δ) (h : HashSet α) : m δ :=
match h with
| ⟨ h, _ ⟩ => h.foldM f init
@[inline] def fold {δ : Type w} (f : δ → α → δ) (init : δ) (m : HashSet α) : δ :=
match m with
| ⟨ m, _ ⟩ => m.fold f init
@[inline] def size (m : HashSet α) : Nat :=
match m with
| ⟨ {size := sz, ..}, _ ⟩ => sz
@[inline] def isEmpty (m : HashSet α) : Bool :=
m.size = 0
@[inline] def empty : HashSet α :=
mkHashSet
def toList (m : HashSet α) : List α :=
m.fold (init := []) fun r a => a::r
def toArray (m : HashSet α) : Array α :=
m.fold (init := #[]) fun r a => r.push a
def numBuckets (m : HashSet α) : Nat :=
m.val.buckets.val.size
end HashSet
end Std
|
b156623f62a9479c2c73b4d5e076e7b70042e3ff | 947b78d97130d56365ae2ec264df196ce769371a | /tests/lean/inst.lean | 37cd398715ec6a913c34fa1b654adbd9c7af209f | [
"Apache-2.0"
] | permissive | shyamalschandra/lean4 | 27044812be8698f0c79147615b1d5090b9f4b037 | 6e7a883b21eaf62831e8111b251dc9b18f40e604 | refs/heads/master | 1,671,417,126,371 | 1,601,859,995,000 | 1,601,860,020,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 508 | lean | import Lean.Expr
new_frontend
open Lean
def tst : IO Unit :=
do
let f := mkConst `f;
let x := mkBVar 0;
let y := mkBVar 1;
let t := mkApp (mkApp (mkApp f x) y) x;
let a := mkConst `a;
let b := mkApp f (mkConst `b);
let c := mkConst `c;
IO.println t;
IO.println (t.instantiate #[a, b]);
IO.println (t.instantiateRange 0 2 #[a, b]);
IO.println (t.instantiateRange 2 4 #[c, c, a, b, c]);
IO.println (t.instantiateRev #[a, b]);
IO.println (t.instantiate #[a]);
IO.println (t.instantiate1 a);
pure ()
#eval tst
|
25baecb81328ca57b80c92f3bba8a958a0867746 | c777c32c8e484e195053731103c5e52af26a25d1 | /src/algebraic_topology/dold_kan/gamma_comp_n.lean | b3d66c5c2cfccb0b0bbb45a03c10cef6309b4980 | [
"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 | 6,614 | lean | /-
Copyright (c) 2022 Joël Riou. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Joël Riou
-/
import algebraic_topology.dold_kan.functor_gamma
import category_theory.idempotents.homological_complex
/-!
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> Any changes to this file require a corresponding PR to mathlib4.
The counit isomorphism of the Dold-Kan equivalence
The purpose of this file is to construct natural isomorphisms
`N₁Γ₀ : Γ₀ ⋙ N₁ ≅ to_karoubi (chain_complex C ℕ)`
and `N₂Γ₂ : Γ₂ ⋙ N₂ ≅ 𝟭 (karoubi (chain_complex C ℕ))`.
-/
noncomputable theory
open category_theory category_theory.category category_theory.limits category_theory.idempotents
opposite simplicial_object
open_locale simplicial
namespace algebraic_topology
namespace dold_kan
variables {C : Type*} [category C] [preadditive C] [has_finite_coproducts C]
/-- The isomorphism `(Γ₀.splitting K).nondeg_complex ≅ K` for all `K : chain_complex C ℕ`. -/
@[simps]
def Γ₀_nondeg_complex_iso (K : chain_complex C ℕ) : (Γ₀.splitting K).nondeg_complex ≅ K :=
homological_complex.hom.iso_of_components (λ n, iso.refl _)
begin
rintros _ n (rfl : n+1=_),
dsimp,
simp only [id_comp, comp_id, alternating_face_map_complex.obj_d_eq,
preadditive.sum_comp, preadditive.comp_sum],
rw fintype.sum_eq_single (0 : fin (n+2)),
{ simp only [fin.coe_zero, pow_zero, one_zsmul],
erw [Γ₀.obj.map_mono_on_summand_id_assoc, Γ₀.obj.termwise.map_mono_δ₀,
splitting.ι_π_summand_eq_id, comp_id], },
{ intros i hi,
dsimp,
simp only [preadditive.zsmul_comp, preadditive.comp_zsmul, assoc],
erw [Γ₀.obj.map_mono_on_summand_id_assoc, Γ₀.obj.termwise.map_mono_eq_zero,
zero_comp, zsmul_zero],
{ intro h,
replace h := congr_arg simplex_category.len h,
change n+1 = n at h,
linarith, },
{ simpa only [is_δ₀.iff] using hi, }, },
end
/-- The natural isomorphism `(Γ₀.splitting K).nondeg_complex ≅ K` for `K : chain_complex C ℕ`. -/
def Γ₀'_comp_nondeg_complex_functor :
Γ₀' ⋙ split.nondeg_complex_functor ≅ 𝟭 (chain_complex C ℕ) :=
nat_iso.of_components Γ₀_nondeg_complex_iso
(λ X Y f, by { ext n, dsimp, simp only [comp_id, id_comp], })
/-- The natural isomorphism `Γ₀ ⋙ N₁ ≅ to_karoubi (chain_complex C ℕ)`. -/
def N₁Γ₀ : Γ₀ ⋙ N₁ ≅ to_karoubi (chain_complex C ℕ) :=
calc Γ₀ ⋙ N₁ ≅ Γ₀' ⋙ split.forget C ⋙ N₁ : functor.associator _ _ _
... ≅ Γ₀' ⋙ split.nondeg_complex_functor ⋙ to_karoubi _ :
iso_whisker_left Γ₀' split.to_karoubi_nondeg_complex_functor_iso_N₁.symm
... ≅ (Γ₀' ⋙ split.nondeg_complex_functor) ⋙ to_karoubi _ : (functor.associator _ _ _).symm
... ≅ 𝟭 _ ⋙ to_karoubi (chain_complex C ℕ) : iso_whisker_right Γ₀'_comp_nondeg_complex_functor _
... ≅ to_karoubi (chain_complex C ℕ) : functor.left_unitor _
lemma N₁Γ₀_app (K : chain_complex C ℕ) :
N₁Γ₀.app K = (Γ₀.splitting K).to_karoubi_nondeg_complex_iso_N₁.symm
≪≫ (to_karoubi _).map_iso (Γ₀_nondeg_complex_iso K) :=
begin
ext1,
dsimp [N₁Γ₀],
erw [id_comp, comp_id, comp_id],
refl,
end
lemma N₁Γ₀_hom_app (K : chain_complex C ℕ) :
N₁Γ₀.hom.app K = (Γ₀.splitting K).to_karoubi_nondeg_complex_iso_N₁.inv
≫ (to_karoubi _).map (Γ₀_nondeg_complex_iso K).hom :=
by { change (N₁Γ₀.app K).hom = _, simpa only [N₁Γ₀_app], }
lemma N₁Γ₀_inv_app (K : chain_complex C ℕ) :
N₁Γ₀.inv.app K = (to_karoubi _).map (Γ₀_nondeg_complex_iso K).inv ≫
(Γ₀.splitting K).to_karoubi_nondeg_complex_iso_N₁.hom :=
by { change (N₁Γ₀.app K).inv = _, simpa only [N₁Γ₀_app], }
@[simp]
lemma N₁Γ₀_hom_app_f_f (K : chain_complex C ℕ) (n : ℕ) :
(N₁Γ₀.hom.app K).f.f n = (Γ₀.splitting K).to_karoubi_nondeg_complex_iso_N₁.inv.f.f n :=
by { rw N₁Γ₀_hom_app, apply comp_id, }
@[simp]
lemma N₁Γ₀_inv_app_f_f (K : chain_complex C ℕ) (n : ℕ) :
(N₁Γ₀.inv.app K).f.f n = (Γ₀.splitting K).to_karoubi_nondeg_complex_iso_N₁.hom.f.f n :=
by { rw N₁Γ₀_inv_app, apply id_comp, }
lemma N₂Γ₂_to_karoubi : to_karoubi (chain_complex C ℕ) ⋙ Γ₂ ⋙ N₂ = Γ₀ ⋙ N₁ :=
begin
have h := functor.congr_obj (functor_extension₂_comp_whiskering_left_to_karoubi
(chain_complex C ℕ) (simplicial_object C)) Γ₀,
have h' := functor.congr_obj (functor_extension₁_comp_whiskering_left_to_karoubi
(simplicial_object C) (chain_complex C ℕ)) N₁,
dsimp [N₂, Γ₂, functor_extension₁] at h h' ⊢,
rw [← functor.assoc, h, functor.assoc, h'],
end
/-- Compatibility isomorphism between `to_karoubi _ ⋙ Γ₂ ⋙ N₂` and `Γ₀ ⋙ N₁` which
are functors `chain_complex C ℕ ⥤ karoubi (chain_complex C ℕ)`. -/
@[simps]
def N₂Γ₂_to_karoubi_iso : to_karoubi (chain_complex C ℕ) ⋙ Γ₂ ⋙ N₂ ≅ Γ₀ ⋙ N₁ :=
eq_to_iso (N₂Γ₂_to_karoubi)
/-- The counit isomorphism of the Dold-Kan equivalence for additive categories. -/
def N₂Γ₂ : Γ₂ ⋙ N₂ ≅ 𝟭 (karoubi (chain_complex C ℕ)) :=
((whiskering_left _ _ _).obj (to_karoubi (chain_complex C ℕ))).preimage_iso
(N₂Γ₂_to_karoubi_iso ≪≫ N₁Γ₀)
lemma N₂Γ₂_compatible_with_N₁Γ₀ (K : chain_complex C ℕ) :
N₂Γ₂.hom.app ((to_karoubi _).obj K) = N₂Γ₂_to_karoubi_iso.hom.app K ≫ N₁Γ₀.hom.app K :=
congr_app (((whiskering_left _ _ (karoubi (chain_complex C ℕ ))).obj
(to_karoubi (chain_complex C ℕ))).image_preimage
(N₂Γ₂_to_karoubi_iso.hom ≫ N₁Γ₀.hom : _ ⟶ to_karoubi _ ⋙ 𝟭 _)) K
@[simp]
lemma N₂Γ₂_inv_app_f_f (X : karoubi (chain_complex C ℕ)) (n : ℕ) :
(N₂Γ₂.inv.app X).f.f n =
X.p.f n ≫ (Γ₀.splitting X.X).ι_summand (splitting.index_set.id (op [n])) :=
begin
dsimp only [N₂Γ₂, functor.preimage_iso, iso.trans],
simp only [whiskering_left_obj_preimage_app, N₂Γ₂_to_karoubi_iso_inv, functor.id_map,
nat_trans.comp_app, eq_to_hom_app, functor.comp_map, assoc, karoubi.comp_f,
karoubi.eq_to_hom_f, eq_to_hom_refl, comp_id, karoubi.comp_p_assoc, N₂_map_f_f,
homological_complex.comp_f, N₁Γ₀_inv_app_f_f, P_infty_on_Γ₀_splitting_summand_eq_self_assoc,
splitting.to_karoubi_nondeg_complex_iso_N₁_hom_f_f, Γ₂_map_f_app, karoubi.decomp_id_p_f],
dsimp [to_karoubi],
rw [splitting.ι_desc],
dsimp [splitting.index_set.id],
rw karoubi.homological_complex.p_idem_assoc,
end
end dold_kan
end algebraic_topology
|
611685738e0d83cb892ac9c624e6809a2bfe4646 | d9d511f37a523cd7659d6f573f990e2a0af93c6f | /src/algebra/group_power/order.lean | c6d689bc025af31a57a395898c3ce0ee6fe0f4c3 | [
"Apache-2.0"
] | permissive | hikari0108/mathlib | b7ea2b7350497ab1a0b87a09d093ecc025a50dfa | a9e7d333b0cfd45f13a20f7b96b7d52e19fa2901 | refs/heads/master | 1,690,483,608,260 | 1,631,541,580,000 | 1,631,541,580,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 10,636 | lean | /-
Copyright (c) 2015 Jeremy Avigad. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jeremy Avigad, Robert Y. Lewis
-/
import algebra.ordered_ring
import algebra.group_power.basic
/-!
# Lemmas about the interaction of power operations with order
Note that some lemmas are in `algebra/group_power/lemmas.lean` as they import files which
depend on this file.
-/
variables {A G M R : Type*}
section preorder
variables [monoid M] [preorder M] [covariant_class M M (*) (≤)]
@[mono, to_additive nsmul_le_nsmul_of_le_right]
lemma pow_le_pow_of_le_left' [covariant_class M M (function.swap (*)) (≤)]
{a b : M} (hab : a ≤ b) : ∀ i : ℕ, a ^ i ≤ b ^ i
| 0 := by simp
| (k+1) := by { rw [pow_succ, pow_succ],
exact mul_le_mul' hab (pow_le_pow_of_le_left' k) }
@[to_additive nsmul_nonneg]
theorem one_le_pow_of_one_le' {a : M} (H : 1 ≤ a) : ∀ n : ℕ, 1 ≤ a ^ n
| 0 := by simp
| (k + 1) := by { rw pow_succ, exact one_le_mul H (one_le_pow_of_one_le' k) }
@[to_additive nsmul_nonpos]
theorem pow_le_one' {a : M} (H : a ≤ 1) (n : ℕ) : a ^ n ≤ 1 :=
@one_le_pow_of_one_le' (order_dual M) _ _ _ _ H n
@[to_additive nsmul_le_nsmul]
theorem pow_le_pow' {a : M} {n m : ℕ} (ha : 1 ≤ a) (h : n ≤ m) : a ^ n ≤ a ^ m :=
let ⟨k, hk⟩ := nat.le.dest h in
calc a ^ n ≤ a ^ n * a ^ k : le_mul_of_one_le_right' (one_le_pow_of_one_le' ha _)
... = a ^ m : by rw [← hk, pow_add]
@[to_additive nsmul_le_nsmul_of_nonpos]
theorem pow_le_pow_of_le_one' {a : M} {n m : ℕ} (ha : a ≤ 1) (h : n ≤ m) : a ^ m ≤ a ^ n :=
@pow_le_pow' (order_dual M) _ _ _ _ _ _ ha h
@[to_additive nsmul_pos]
theorem one_lt_pow' {a : M} (ha : 1 < a) {k : ℕ} (hk : k ≠ 0) : 1 < a ^ k :=
begin
rcases nat.exists_eq_succ_of_ne_zero hk with ⟨l, rfl⟩,
clear hk,
induction l with l IH,
{ simpa using ha },
{ rw pow_succ,
exact one_lt_mul' ha IH }
end
@[to_additive nsmul_neg]
theorem pow_lt_one' {a : M} (ha : a < 1) {k : ℕ} (hk : k ≠ 0) : a ^ k < 1 :=
@one_lt_pow' (order_dual M) _ _ _ _ ha k hk
@[to_additive nsmul_lt_nsmul]
theorem pow_lt_pow'' [covariant_class M M (*) (<)] {a : M} {n m : ℕ} (ha : 1 < a) (h : n < m) :
a ^ n < a ^ m :=
begin
rcases nat.le.dest h with ⟨k, rfl⟩, clear h,
rw [pow_add, pow_succ', mul_assoc, ← pow_succ],
exact lt_mul_of_one_lt_right' _ (one_lt_pow' ha k.succ_ne_zero)
end
end preorder
section linear_order
variables [monoid M] [linear_order M] [covariant_class M M (*) (≤)]
@[to_additive nsmul_nonneg_iff]
lemma one_le_pow_iff {x : M} {n : ℕ} (hn : n ≠ 0) : 1 ≤ x ^ n ↔ 1 ≤ x :=
⟨le_imp_le_of_lt_imp_lt $ λ h, pow_lt_one' h hn, λ h, one_le_pow_of_one_le' h n⟩
@[to_additive nsmul_nonpos_iff]
lemma pow_le_one_iff {x : M} {n : ℕ} (hn : n ≠ 0) : x ^ n ≤ 1 ↔ x ≤ 1 :=
@one_le_pow_iff (order_dual M) _ _ _ _ _ hn
@[to_additive nsmul_pos_iff]
lemma one_lt_pow_iff {x : M} {n : ℕ} (hn : n ≠ 0) : 1 < x ^ n ↔ 1 < x :=
lt_iff_lt_of_le_iff_le (pow_le_one_iff hn)
@[to_additive nsmul_neg_iff]
lemma pow_lt_one_iff {x : M} {n : ℕ} (hn : n ≠ 0) : x ^ n < 1 ↔ x < 1 :=
lt_iff_lt_of_le_iff_le (one_le_pow_iff hn)
@[to_additive nsmul_eq_zero_iff]
lemma pow_eq_one_iff {x : M} {n : ℕ} (hn : n ≠ 0) : x ^ n = 1 ↔ x = 1 :=
by simp only [le_antisymm_iff, pow_le_one_iff hn, one_le_pow_iff hn]
end linear_order
section group
variables [group G] [preorder G] [covariant_class G G (*) (≤)]
@[to_additive gsmul_nonneg]
theorem one_le_gpow {x : G} (H : 1 ≤ x) {n : ℤ} (hn : 0 ≤ n) :
1 ≤ x ^ n :=
begin
lift n to ℕ using hn,
rw gpow_coe_nat,
apply one_le_pow_of_one_le' H,
end
end group
namespace canonically_ordered_comm_semiring
variables [canonically_ordered_comm_semiring R]
theorem pow_pos {a : R} (H : 0 < a) (n : ℕ) : 0 < a ^ n :=
pos_iff_ne_zero.2 $ pow_ne_zero _ H.ne'
end canonically_ordered_comm_semiring
section ordered_semiring
variable [ordered_semiring R]
@[simp] theorem pow_pos {a : R} (H : 0 < a) : ∀ (n : ℕ), 0 < a ^ n
| 0 := by { nontriviality, rw pow_zero, exact zero_lt_one }
| (n+1) := by { rw pow_succ, exact mul_pos H (pow_pos _) }
@[simp] theorem pow_nonneg {a : R} (H : 0 ≤ a) : ∀ (n : ℕ), 0 ≤ a ^ n
| 0 := by { rw pow_zero, exact zero_le_one}
| (n+1) := by { rw pow_succ, exact mul_nonneg H (pow_nonneg _) }
theorem pow_add_pow_le {x y : R} {n : ℕ} (hx : 0 ≤ x) (hy : 0 ≤ y) (hn : n ≠ 0) :
x ^ n + y ^ n ≤ (x + y) ^ n :=
begin
rcases nat.exists_eq_succ_of_ne_zero hn with ⟨k, rfl⟩,
induction k with k ih, { simp only [pow_one] },
let n := k.succ,
have h1 := add_nonneg (mul_nonneg hx (pow_nonneg hy n)) (mul_nonneg hy (pow_nonneg hx n)),
have h2 := add_nonneg hx hy,
calc x^n.succ + y^n.succ
≤ x*x^n + y*y^n + (x*y^n + y*x^n) :
by { rw [pow_succ _ n, pow_succ _ n], exact le_add_of_nonneg_right h1 }
... = (x+y) * (x^n + y^n) :
by rw [add_mul, mul_add, mul_add, add_comm (y*x^n), ← add_assoc,
← add_assoc, add_assoc (x*x^n) (x*y^n), add_comm (x*y^n) (y*y^n), ← add_assoc]
... ≤ (x+y)^n.succ :
by { rw [pow_succ _ n], exact mul_le_mul_of_nonneg_left (ih (nat.succ_ne_zero k)) h2 }
end
theorem pow_lt_pow_of_lt_left {x y : R} {n : ℕ} (Hxy : x < y) (Hxpos : 0 ≤ x) (Hnpos : 0 < n) :
x ^ n < y ^ n :=
begin
cases lt_or_eq_of_le Hxpos,
{ rw ←nat.sub_add_cancel Hnpos,
induction (n - 1), { simpa only [pow_one] },
rw [pow_add, pow_add, nat.succ_eq_add_one, pow_one, pow_one],
apply mul_lt_mul ih (le_of_lt Hxy) h (le_of_lt (pow_pos (lt_trans h Hxy) _)) },
{ rw [←h, zero_pow Hnpos], apply pow_pos (by rwa ←h at Hxy : 0 < y),}
end
theorem strict_mono_incr_on_pow {n : ℕ} (hn : 0 < n) :
strict_mono_incr_on (λ x : R, x ^ n) (set.Ici 0) :=
λ x hx y hy h, pow_lt_pow_of_lt_left h hx hn
theorem one_le_pow_of_one_le {a : R} (H : 1 ≤ a) : ∀ (n : ℕ), 1 ≤ a ^ n
| 0 := by rw [pow_zero]
| (n+1) := by { rw pow_succ, simpa only [mul_one] using mul_le_mul H (one_le_pow_of_one_le n)
zero_le_one (le_trans zero_le_one H) }
lemma pow_mono {a : R} (h : 1 ≤ a) : monotone (λ n : ℕ, a ^ n) :=
monotone_nat_of_le_succ $ λ n,
by { rw pow_succ, exact le_mul_of_one_le_left (pow_nonneg (zero_le_one.trans h) _) h }
theorem pow_le_pow {a : R} {n m : ℕ} (ha : 1 ≤ a) (h : n ≤ m) : a ^ n ≤ a ^ m :=
pow_mono ha h
lemma strict_mono_pow {a : R} (h : 1 < a) : strict_mono (λ n : ℕ, a ^ n) :=
have 0 < a := zero_le_one.trans_lt h,
strict_mono_nat_of_lt_succ $ λ n, by simpa only [one_mul, pow_succ]
using mul_lt_mul h (le_refl (a ^ n)) (pow_pos this _) this.le
lemma pow_lt_pow {a : R} {n m : ℕ} (h : 1 < a) (h2 : n < m) : a ^ n < a ^ m :=
strict_mono_pow h h2
lemma pow_lt_pow_iff {a : R} {n m : ℕ} (h : 1 < a) : a ^ n < a ^ m ↔ n < m :=
(strict_mono_pow h).lt_iff_lt
@[mono] lemma pow_le_pow_of_le_left {a b : R} (ha : 0 ≤ a) (hab : a ≤ b) : ∀ i : ℕ, a^i ≤ b^i
| 0 := by simp
| (k+1) := by { rw [pow_succ, pow_succ],
exact mul_le_mul hab (pow_le_pow_of_le_left _) (pow_nonneg ha _) (le_trans ha hab) }
end ordered_semiring
section linear_ordered_semiring
variable [linear_ordered_semiring R]
@[simp] theorem pow_left_inj {x y : R} {n : ℕ} (Hxpos : 0 ≤ x) (Hypos : 0 ≤ y) (Hnpos : 0 < n) :
x ^ n = y ^ n ↔ x = y :=
(@strict_mono_incr_on_pow R _ _ Hnpos).inj_on.eq_iff Hxpos Hypos
lemma lt_of_pow_lt_pow {a b : R} (n : ℕ) (hb : 0 ≤ b) (h : a ^ n < b ^ n) : a < b :=
lt_of_not_ge $ λ hn, not_lt_of_ge (pow_le_pow_of_le_left hb hn _) h
lemma le_of_pow_le_pow {a b : R} (n : ℕ) (hb : 0 ≤ b) (hn : 0 < n) (h : a ^ n ≤ b ^ n) : a ≤ b :=
le_of_not_lt $ λ h1, not_le_of_lt (pow_lt_pow_of_lt_left h1 hb hn) h
@[simp] lemma sq_eq_sq {a b : R} (ha : 0 ≤ a) (hb : 0 ≤ b) : a ^ 2 = b ^ 2 ↔ a = b :=
pow_left_inj ha hb dec_trivial
end linear_ordered_semiring
section linear_ordered_ring
variable [linear_ordered_ring R]
lemma pow_abs (a : R) (n : ℕ) : (abs a) ^ n = abs (a ^ n) :=
((abs_hom.to_monoid_hom : R →* R).map_pow a n).symm
lemma abs_neg_one_pow (n : ℕ) : abs ((-1 : R) ^ n) = 1 :=
by rw [←pow_abs, abs_neg, abs_one, one_pow]
theorem pow_bit0_nonneg (a : R) (n : ℕ) : 0 ≤ a ^ bit0 n :=
by { rw pow_bit0, exact mul_self_nonneg _ }
theorem sq_nonneg (a : R) : 0 ≤ a ^ 2 :=
pow_bit0_nonneg a 1
alias sq_nonneg ← pow_two_nonneg
theorem pow_bit0_pos {a : R} (h : a ≠ 0) (n : ℕ) : 0 < a ^ bit0 n :=
(pow_bit0_nonneg a n).lt_of_ne (pow_ne_zero _ h).symm
theorem sq_pos_of_ne_zero (a : R) (h : a ≠ 0) : 0 < a ^ 2 :=
pow_bit0_pos h 1
alias sq_pos_of_ne_zero ← pow_two_pos_of_ne_zero
variables {x y : R}
theorem sq_abs (x : R) : abs x ^ 2 = x ^ 2 :=
by simpa only [sq] using abs_mul_abs_self x
theorem abs_sq (x : R) : abs (x ^ 2) = x ^ 2 :=
by simpa only [sq] using abs_mul_self x
theorem sq_lt_sq (h : abs x < y) : x ^ 2 < y ^ 2 :=
by simpa only [sq_abs] using pow_lt_pow_of_lt_left h (abs_nonneg x) (1:ℕ).succ_pos
theorem sq_lt_sq' (h1 : -y < x) (h2 : x < y) : x ^ 2 < y ^ 2 :=
sq_lt_sq (abs_lt.mpr ⟨h1, h2⟩)
theorem sq_le_sq (h : abs x ≤ abs y) : x ^ 2 ≤ y ^ 2 :=
by simpa only [sq_abs] using pow_le_pow_of_le_left (abs_nonneg x) h 2
theorem sq_le_sq' (h1 : -y ≤ x) (h2 : x ≤ y) : x ^ 2 ≤ y ^ 2 :=
sq_le_sq (le_trans (abs_le.mpr ⟨h1, h2⟩) (le_abs_self _))
theorem abs_lt_abs_of_sq_lt_sq (h : x^2 < y^2) : abs x < abs y :=
lt_of_pow_lt_pow 2 (abs_nonneg y) $ by rwa [← sq_abs x, ← sq_abs y] at h
theorem abs_lt_of_sq_lt_sq (h : x^2 < y^2) (hy : 0 ≤ y) : abs x < y :=
begin
rw [← abs_of_nonneg hy],
exact abs_lt_abs_of_sq_lt_sq h,
end
theorem abs_lt_of_sq_lt_sq' (h : x^2 < y^2) (hy : 0 ≤ y) : -y < x ∧ x < y :=
abs_lt.mp $ abs_lt_of_sq_lt_sq h hy
theorem abs_le_abs_of_sq_le_sq (h : x^2 ≤ y^2) : abs x ≤ abs y :=
le_of_pow_le_pow 2 (abs_nonneg y) (1:ℕ).succ_pos $ by rwa [← sq_abs x, ← sq_abs y] at h
theorem abs_le_of_sq_le_sq (h : x^2 ≤ y^2) (hy : 0 ≤ y) : abs x ≤ y :=
begin
rw [← abs_of_nonneg hy],
exact abs_le_abs_of_sq_le_sq h,
end
theorem abs_le_of_sq_le_sq' (h : x^2 ≤ y^2) (hy : 0 ≤ y) : -y ≤ x ∧ x ≤ y :=
abs_le.mp $ abs_le_of_sq_le_sq h hy
end linear_ordered_ring
section linear_ordered_comm_ring
variables [linear_ordered_comm_ring R]
/-- Arithmetic mean-geometric mean (AM-GM) inequality for linearly ordered commutative rings. -/
lemma two_mul_le_add_sq (a b : R) : 2 * a * b ≤ a ^ 2 + b ^ 2 :=
sub_nonneg.mp ((sub_add_eq_add_sub _ _ _).subst ((sub_sq a b).subst (sq_nonneg _)))
alias two_mul_le_add_sq ← two_mul_le_add_pow_two
end linear_ordered_comm_ring
|
8db9b5cee0e0f8f8913ee4c6e25923726016d601 | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/combinatorics/quiver/basic.lean | 2e3527deffeb22347ca478a95ee178c553334383 | [
"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 | 4,176 | lean | /-
Copyright (c) 2021 David Wärn. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: David Wärn, Scott Morrison
-/
import data.opposite
/-!
# Quivers
> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
> https://github.com/leanprover-community/mathlib4/pull/749
> Any changes to this file require a corresponding PR to mathlib4.
This module defines quivers. A quiver on a type `V` of vertices assigns to every
pair `a b : V` of vertices a type `a ⟶ b` of arrows from `a` to `b`. This
is a very permissive notion of directed graph.
## Implementation notes
Currently `quiver` is defined with `arrow : V → V → Sort v`.
This is different from the category theory setup,
where we insist that morphisms live in some `Type`.
There's some balance here: it's nice to allow `Prop` to ensure there are no multiple arrows,
but it is also results in error-prone universe signatures when constraints require a `Type`.
-/
open opposite
-- We use the same universe order as in category theory.
-- See note [category_theory universes]
universes v v₁ v₂ u u₁ u₂
/--
A quiver `G` on a type `V` of vertices assigns to every pair `a b : V` of vertices
a type `a ⟶ b` of arrows from `a` to `b`.
For graphs with no repeated edges, one can use `quiver.{0} V`, which ensures
`a ⟶ b : Prop`. For multigraphs, one can use `quiver.{v+1} V`, which ensures
`a ⟶ b : Type v`.
Because `category` will later extend this class, we call the field `hom`.
Except when constructing instances, you should rarely see this, and use the `⟶` notation instead.
-/
class quiver (V : Type u) :=
(hom : V → V → Sort v)
infixr ` ⟶ `:10 := quiver.hom -- type as \h
/--
A morphism of quivers. As we will later have categorical functors extend this structure,
we call it a `prefunctor`.
-/
structure prefunctor (V : Type u₁) [quiver.{v₁} V] (W : Type u₂) [quiver.{v₂} W] :=
(obj [] : V → W)
(map : Π {X Y : V}, (X ⟶ Y) → (obj X ⟶ obj Y))
namespace prefunctor
@[ext]
lemma ext {V : Type u} [quiver.{v₁} V] {W : Type u₂} [quiver.{v₂} W]
{F G : prefunctor V W}
(h_obj : ∀ X, F.obj X = G.obj X)
(h_map : ∀ (X Y : V) (f : X ⟶ Y),
F.map f = eq.rec_on (h_obj Y).symm (eq.rec_on (h_obj X).symm (G.map f))) : F = G :=
begin
cases F with F_obj _, cases G with G_obj _,
obtain rfl : F_obj = G_obj, by { ext X, apply h_obj },
congr,
funext X Y f,
simpa using h_map X Y f,
end
/--
The identity morphism between quivers.
-/
@[simps]
def id (V : Type*) [quiver V] : prefunctor V V :=
{ obj := id,
map := λ X Y f, f, }
instance (V : Type*) [quiver V] : inhabited (prefunctor V V) := ⟨id V⟩
/--
Composition of morphisms between quivers.
-/
@[simps]
def comp {U : Type*} [quiver U] {V : Type*} [quiver V] {W : Type*} [quiver W]
(F : prefunctor U V) (G : prefunctor V W) : prefunctor U W :=
{ obj := λ X, G.obj (F.obj X),
map := λ X Y f, G.map (F.map f), }
@[simp]
lemma comp_assoc
{U V W Z : Type*} [quiver U] [quiver V] [quiver W] [quiver Z]
(F : prefunctor U V) (G : prefunctor V W) (H : prefunctor W Z) :
(F.comp G).comp H = F.comp (G.comp H) := rfl
infix ` ⥤q `:50 := prefunctor
infix ` ⋙q `:50 := prefunctor.comp
notation `𝟭q` := id
end prefunctor
namespace quiver
/-- `Vᵒᵖ` reverses the direction of all arrows of `V`. -/
instance opposite {V} [quiver V] : quiver Vᵒᵖ :=
⟨λ a b, (unop b) ⟶ (unop a)⟩
/--
The opposite of an arrow in `V`.
-/
def hom.op {V} [quiver V] {X Y : V} (f : X ⟶ Y) : op Y ⟶ op X := f
/--
Given an arrow in `Vᵒᵖ`, we can take the "unopposite" back in `V`.
-/
def hom.unop {V} [quiver V] {X Y : Vᵒᵖ} (f : X ⟶ Y) : unop Y ⟶ unop X := f
attribute [irreducible] quiver.opposite
/-- A type synonym for a quiver with no arrows. -/
@[nolint has_nonempty_instance]
def empty (V) : Type u := V
instance empty_quiver (V : Type u) : quiver.{u} (empty V) := ⟨λ a b, pempty⟩
@[simp] lemma empty_arrow {V : Type u} (a b : empty V) : (a ⟶ b) = pempty := rfl
/-- A quiver is thin if it has no parallel arrows. -/
@[reducible] def is_thin (V : Type u) [quiver V] := ∀ (a b : V), subsingleton (a ⟶ b)
end quiver
|
50d42a9ac1992dea126827f09eeb80e64b54b641 | 75db7e3219bba2fbf41bf5b905f34fcb3c6ca3f2 | /library/algebra/field.lean | 4005daf5fcdde5b75dbd11d4d011bfd68d6462ea | [
"Apache-2.0"
] | permissive | jroesch/lean | 30ef0860fa905d35b9ad6f76de1a4f65c9af6871 | 3de4ec1a6ce9a960feb2a48eeea8b53246fa34f2 | refs/heads/master | 1,586,090,835,348 | 1,455,142,203,000 | 1,455,142,277,000 | 51,536,958 | 1 | 0 | null | 1,455,215,811,000 | 1,455,215,811,000 | null | UTF-8 | Lean | false | false | 20,340 | lean | /-
Copyright (c) 2014 Robert Lewis. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Robert Lewis
Structures with multiplicative and additive components, including division rings and fields.
The development is modeled after Isabelle's library.
-/
import logic.eq logic.connectives data.unit data.sigma data.prod
import algebra.binary algebra.group algebra.ring
open eq eq.ops
variable {A : Type}
structure division_ring [class] (A : Type) extends ring A, has_inv A, zero_ne_one_class A :=
(mul_inv_cancel : ∀{a}, a ≠ zero → mul a (inv a) = one)
(inv_mul_cancel : ∀{a}, a ≠ zero → mul (inv a) a = one)
section division_ring
variables [s : division_ring A] {a b c : A}
include s
protected definition algebra.div (a b : A) : A := a * b⁻¹
definition division_ring_has_div [reducible] [instance] : has_div A :=
has_div.mk algebra.div
lemma division.def [simp] (a b : A) : a / b = a * b⁻¹ :=
rfl
theorem mul_inv_cancel [simp] (H : a ≠ 0) : a * a⁻¹ = 1 :=
division_ring.mul_inv_cancel H
theorem inv_mul_cancel [simp] (H : a ≠ 0) : a⁻¹ * a = 1 :=
division_ring.inv_mul_cancel H
theorem inv_eq_one_div (a : A) : a⁻¹ = 1 / a := !one_mul⁻¹
theorem div_eq_mul_one_div (a b : A) : a / b = a * (1 / b) :=
by simp
theorem mul_one_div_cancel [simp] (H : a ≠ 0) : a * (1 / a) = 1 :=
by simp
theorem one_div_mul_cancel [simp] (H : a ≠ 0) : (1 / a) * a = 1 :=
by simp
theorem div_self [simp] (H : a ≠ 0) : a / a = 1 :=
by simp
theorem one_div_one [simp] : 1 / 1 = (1:A) :=
div_self (ne.symm zero_ne_one)
theorem mul_div_assoc (a b : A) : (a * b) / c = a * (b / c) :=
by simp
theorem one_div_ne_zero (H : a ≠ 0) : 1 / a ≠ 0 :=
assume H2 : 1 / a = 0,
have C1 : 0 = (1:A), from symm (by rewrite [-(mul_one_div_cancel H), H2, mul_zero]),
absurd C1 zero_ne_one
theorem one_inv_eq [simp] : 1⁻¹ = (1:A) :=
by rewrite [-mul_one, inv_mul_cancel (ne.symm (@zero_ne_one A _))]
theorem div_one [simp] (a : A) : a / 1 = a :=
by simp
theorem zero_div [simp] (a : A) : 0 / a = 0 :=
by simp
-- note: integral domain has a "mul_ne_zero". A commutative division ring is an integral
-- domain, but let's not define that class for now.
theorem division_ring.mul_ne_zero (Ha : a ≠ 0) (Hb : b ≠ 0) : a * b ≠ 0 :=
assume H : a * b = 0,
have C1 : a = 0, by rewrite [-mul_one, -(mul_one_div_cancel Hb), -mul.assoc, H, zero_mul],
absurd C1 Ha
theorem mul_ne_zero_comm (H : a * b ≠ 0) : b * a ≠ 0 :=
have H2 : a ≠ 0 ∧ b ≠ 0, from ne_zero_and_ne_zero_of_mul_ne_zero H,
division_ring.mul_ne_zero (and.right H2) (and.left H2)
theorem eq_one_div_of_mul_eq_one (H : a * b = 1) : b = 1 / a :=
assert a ≠ 0, from
suppose a = 0,
have 0 = (1:A), by inst_simp,
absurd this zero_ne_one,
assert b = (1 / a) * a * b, by inst_simp,
show b = 1 / a, by inst_simp
theorem eq_one_div_of_mul_eq_one_left (H : b * a = 1) : b = 1 / a :=
assert a ≠ 0, from
suppose a = 0,
have 0 = (1:A), by inst_simp,
absurd this zero_ne_one,
by inst_simp
theorem division_ring.one_div_mul_one_div (Ha : a ≠ 0) (Hb : b ≠ 0) :
(1 / a) * (1 / b) = 1 / (b * a) :=
have (b * a) * ((1 / a) * (1 / b)) = 1, by inst_simp,
eq_one_div_of_mul_eq_one this
theorem one_div_neg_one_eq_neg_one : (1:A) / (-1) = -1 :=
have (-1) * (-1) = (1:A), by inst_simp,
symm (eq_one_div_of_mul_eq_one this)
theorem division_ring.one_div_neg_eq_neg_one_div (H : a ≠ 0) : 1 / (- a) = - (1 / a) :=
have -1 ≠ 0, from
(suppose -1 = 0, absurd (symm (calc
1 = -(-1) : neg_neg
... = -0 : this
... = (0:A) : neg_zero)) zero_ne_one),
calc
1 / (- a) = 1 / ((-1) * a) : neg_eq_neg_one_mul
... = (1 / a) * (1 / (- 1)) : division_ring.one_div_mul_one_div H this
... = (1 / a) * (-1) : one_div_neg_one_eq_neg_one
... = - (1 / a) : mul_neg_one_eq_neg
theorem div_neg_eq_neg_div (b : A) (Ha : a ≠ 0) : b / (- a) = - (b / a) :=
calc
b / (- a) = b * (1 / (- a)) : by rewrite -inv_eq_one_div
... = b * -(1 / a) : division_ring.one_div_neg_eq_neg_one_div Ha
... = -(b * (1 / a)) : neg_mul_eq_mul_neg
... = - (b * a⁻¹) : inv_eq_one_div
theorem neg_div (a b : A) : (-b) / a = - (b / a) :=
by rewrite [neg_eq_neg_one_mul, mul_div_assoc, -neg_eq_neg_one_mul]
theorem division_ring.neg_div_neg_eq (a : A) {b : A} (Hb : b ≠ 0) : (-a) / (-b) = a / b :=
by rewrite [(div_neg_eq_neg_div _ Hb), neg_div, neg_neg]
theorem division_ring.one_div_one_div (H : a ≠ 0) : 1 / (1 / a) = a :=
symm (eq_one_div_of_mul_eq_one_left (mul_one_div_cancel H))
theorem division_ring.eq_of_one_div_eq_one_div (Ha : a ≠ 0) (Hb : b ≠ 0) (H : 1 / a = 1 / b) :
a = b :=
by rewrite [-(division_ring.one_div_one_div Ha), H, (division_ring.one_div_one_div Hb)]
theorem mul_inv_eq [simp] (Ha : a ≠ 0) (Hb : b ≠ 0) : (b * a)⁻¹ = a⁻¹ * b⁻¹ :=
eq.symm (calc
a⁻¹ * b⁻¹ = (1 / a) * (1 / b) : by inst_simp
... = (1 / (b * a)) : division_ring.one_div_mul_one_div Ha Hb
... = (b * a)⁻¹ : by simp)
theorem mul_div_cancel (a : A) {b : A} (Hb : b ≠ 0) : a * b / b = a :=
by simp
theorem div_mul_cancel (a : A) {b : A} (Hb : b ≠ 0) : a / b * b = a :=
by simp
theorem div_add_div_same (a b c : A) : a / c + b / c = (a + b) / c := !right_distrib⁻¹
theorem div_sub_div_same (a b c : A) : (a / c) - (b / c) = (a - b) / c :=
by rewrite [sub_eq_add_neg, -neg_div, div_add_div_same]
theorem one_div_mul_add_mul_one_div_eq_one_div_add_one_div (Ha : a ≠ 0) (Hb : b ≠ 0) :
(1 / a) * (a + b) * (1 / b) = 1 / a + 1 / b :=
by rewrite [(left_distrib (1 / a)), (one_div_mul_cancel Ha), right_distrib, one_mul,
mul.assoc, (mul_one_div_cancel Hb), mul_one, add.comm]
theorem one_div_mul_sub_mul_one_div_eq_one_div_add_one_div (Ha : a ≠ 0) (Hb : b ≠ 0) :
(1 / a) * (b - a) * (1 / b) = 1 / a - 1 / b :=
by rewrite [(mul_sub_left_distrib (1 / a)), (one_div_mul_cancel Ha), mul_sub_right_distrib,
one_mul, mul.assoc, (mul_one_div_cancel Hb), mul_one]
theorem div_eq_one_iff_eq (a : A) {b : A} (Hb : b ≠ 0) : a / b = 1 ↔ a = b :=
iff.intro
(suppose a / b = 1, calc
a = a / b * b : by inst_simp
... = 1 * b : this
... = b : by simp)
(suppose a = b, by simp)
theorem eq_of_div_eq_one (a : A) {b : A} (Hb : b ≠ 0) : a / b = 1 → a = b :=
iff.mp (!div_eq_one_iff_eq Hb)
theorem eq_div_iff_mul_eq (a : A) {b : A} (Hc : c ≠ 0) : a = b / c ↔ a * c = b :=
iff.intro
(suppose a = b / c, by rewrite [this, (!div_mul_cancel Hc)])
(suppose a * c = b, by rewrite [-(!mul_div_cancel Hc), this])
theorem eq_div_of_mul_eq (a b : A) {c : A} (Hc : c ≠ 0) : a * c = b → a = b / c :=
iff.mpr (!eq_div_iff_mul_eq Hc)
theorem mul_eq_of_eq_div (a b: A) {c : A} (Hc : c ≠ 0) : a = b / c → a * c = b :=
iff.mp (!eq_div_iff_mul_eq Hc)
theorem add_div_eq_mul_add_div (a b : A) {c : A} (Hc : c ≠ 0) : a + b / c = (a * c + b) / c :=
have (a + b / c) * c = a * c + b, by rewrite [right_distrib, (!div_mul_cancel Hc)],
(iff.elim_right (!eq_div_iff_mul_eq Hc)) this
theorem mul_mul_div (a : A) {c : A} (Hc : c ≠ 0) : a = a * c * (1 / c) :=
by simp
-- There are many similar rules to these last two in the Isabelle library
-- that haven't been ported yet. Do as necessary.
end division_ring
structure field [class] (A : Type) extends division_ring A, comm_ring A
section field
variables [s : field A] {a b c d: A}
include s
theorem field.one_div_mul_one_div (Ha : a ≠ 0) (Hb : b ≠ 0) : (1 / a) * (1 / b) = 1 / (a * b) :=
by rewrite [(division_ring.one_div_mul_one_div Ha Hb), mul.comm b]
theorem field.div_mul_right (Hb : b ≠ 0) (H : a * b ≠ 0) : a / (a * b) = 1 / b :=
assert a ≠ 0, from and.left (ne_zero_and_ne_zero_of_mul_ne_zero H),
symm (calc
1 / b = a * ((1 / a) * (1 / b)) : by inst_simp
... = a * (1 / (b * a)) : division_ring.one_div_mul_one_div this Hb
... = a * (a * b)⁻¹ : by inst_simp)
theorem field.div_mul_left (Ha : a ≠ 0) (H : a * b ≠ 0) : b / (a * b) = 1 / a :=
let H1 : b * a ≠ 0 := mul_ne_zero_comm H in
by rewrite [mul.comm a, (field.div_mul_right Ha H1)]
theorem mul_div_cancel_left (Ha : a ≠ 0) : a * b / a = b :=
by rewrite [mul.comm a, (!mul_div_cancel Ha)]
theorem mul_div_cancel' (Hb : b ≠ 0) : b * (a / b) = a :=
by rewrite [mul.comm, (!div_mul_cancel Hb)]
theorem one_div_add_one_div (Ha : a ≠ 0) (Hb : b ≠ 0) : 1 / a + 1 / b = (a + b) / (a * b) :=
assert a * b ≠ 0, from (division_ring.mul_ne_zero Ha Hb),
by rewrite [add.comm, -(field.div_mul_left Ha this), -(field.div_mul_right Hb this), *division.def,
-right_distrib]
theorem field.div_mul_div (a : A) {b : A} (c : A) {d : A} (Hb : b ≠ 0) (Hd : d ≠ 0) :
(a / b) * (c / d) = (a * c) / (b * d) :=
by inst_simp
theorem mul_div_mul_left (a : A) {b c : A} (Hb : b ≠ 0) (Hc : c ≠ 0) :
(c * a) / (c * b) = a / b :=
by rewrite [-(!field.div_mul_div Hc Hb), (div_self Hc), one_mul]
theorem mul_div_mul_right (a : A) {b c : A} (Hb : b ≠ 0) (Hc : c ≠ 0) :
(a * c) / (b * c) = a / b :=
by rewrite [(mul.comm a), (mul.comm b), (!mul_div_mul_left Hb Hc)]
theorem div_mul_eq_mul_div (a b c : A) : (b / c) * a = (b * a) / c :=
by rewrite [*division.def, mul.assoc, (mul.comm c⁻¹), -mul.assoc]
theorem field.div_mul_eq_mul_div_comm (a b : A) {c : A} (Hc : c ≠ 0) :
(b / c) * a = b * (a / c) :=
by rewrite [(div_mul_eq_mul_div), -(one_mul c), -(!field.div_mul_div (ne.symm zero_ne_one) Hc),
div_one, one_mul]
theorem div_add_div (a : A) {b : A} (c : A) {d : A} (Hb : b ≠ 0) (Hd : d ≠ 0) :
(a / b) + (c / d) = ((a * d) + (b * c)) / (b * d) :=
by rewrite [-(!mul_div_mul_right Hb Hd), -(!mul_div_mul_left Hd Hb), div_add_div_same]
theorem div_sub_div (a : A) {b : A} (c : A) {d : A} (Hb : b ≠ 0) (Hd : d ≠ 0) :
(a / b) - (c / d) = ((a * d) - (b * c)) / (b * d) :=
by rewrite [*sub_eq_add_neg, neg_eq_neg_one_mul, -mul_div_assoc, (!div_add_div Hb Hd),
-mul.assoc, (mul.comm b), mul.assoc, -neg_eq_neg_one_mul]
theorem mul_eq_mul_of_div_eq_div (a : A) {b : A} (c : A) {d : A} (Hb : b ≠ 0)
(Hd : d ≠ 0) (H : a / b = c / d) : a * d = c * b :=
by rewrite [-mul_one, mul.assoc, (mul.comm d), -mul.assoc, -(div_self Hb),
-(!field.div_mul_eq_mul_div_comm Hb), H, (div_mul_eq_mul_div), (!div_mul_cancel Hd)]
theorem field.one_div_div (Ha : a ≠ 0) (Hb : b ≠ 0) : 1 / (a / b) = b / a :=
have (a / b) * (b / a) = 1, from calc
(a / b) * (b / a) = (a * b) / (b * a) : !field.div_mul_div Hb Ha
... = (a * b) / (a * b) : mul.comm
... = 1 : div_self (division_ring.mul_ne_zero Ha Hb),
symm (eq_one_div_of_mul_eq_one this)
theorem field.div_div_eq_mul_div (a : A) {b c : A} (Hb : b ≠ 0) (Hc : c ≠ 0) :
a / (b / c) = (a * c) / b :=
by rewrite [div_eq_mul_one_div, (field.one_div_div Hb Hc), -mul_div_assoc]
theorem field.div_div_eq_div_mul (a : A) {b c : A} (Hb : b ≠ 0) (Hc : c ≠ 0) :
(a / b) / c = a / (b * c) :=
by rewrite [div_eq_mul_one_div, (!field.div_mul_div Hb Hc), mul_one]
theorem field.div_div_div_div_eq (a : A) {b c d : A} (Hb : b ≠ 0) (Hc : c ≠ 0) (Hd : d ≠ 0) :
(a / b) / (c / d) = (a * d) / (b * c) :=
by rewrite [(!field.div_div_eq_mul_div Hc Hd), (div_mul_eq_mul_div),
(!field.div_div_eq_div_mul Hb Hc)]
theorem field.div_mul_eq_div_mul_one_div (a : A) {b c : A} (Hb : b ≠ 0) (Hc : c ≠ 0) :
a / (b * c) = (a / b) * (1 / c) :=
by rewrite [-!field.div_div_eq_div_mul Hb Hc, -div_eq_mul_one_div]
theorem eq_of_mul_eq_mul_of_nonzero_left {a b c : A} (H : a ≠ 0) (H2 : a * b = a * c) : b = c :=
by rewrite [-one_mul b, -div_self H, div_mul_eq_mul_div, H2, mul_div_cancel_left H]
theorem eq_of_mul_eq_mul_of_nonzero_right {a b c : A} (H : c ≠ 0) (H2 : a * c = b * c) : a = b :=
by rewrite [-mul_one a, -div_self H, -mul_div_assoc, H2, mul_div_cancel _ H]
end field
structure discrete_field [class] (A : Type) extends field A :=
(has_decidable_eq : decidable_eq A)
(inv_zero : inv zero = zero)
attribute discrete_field.has_decidable_eq [instance]
section discrete_field
variable [s : discrete_field A]
include s
variables {a b c d : A}
-- many of the theorems in discrete_field are the same as theorems in field or division ring,
-- but with fewer hypotheses since 0⁻¹ = 0 and equality is decidable.
theorem discrete_field.eq_zero_or_eq_zero_of_mul_eq_zero
(x y : A) (H : x * y = 0) : x = 0 ∨ y = 0 :=
decidable.by_cases
(suppose x = 0, or.inl this)
(suppose x ≠ 0,
or.inr (by rewrite [-one_mul, -(inv_mul_cancel this), mul.assoc, H, mul_zero]))
definition discrete_field.to_integral_domain [trans_instance] [reducible] :
integral_domain A :=
⦃ integral_domain, s,
eq_zero_or_eq_zero_of_mul_eq_zero := discrete_field.eq_zero_or_eq_zero_of_mul_eq_zero⦄
theorem inv_zero : 0⁻¹ = (0:A) := !discrete_field.inv_zero
theorem one_div_zero : 1 / 0 = (0:A) :=
calc
1 / 0 = 1 * 0⁻¹ : refl
... = 1 * 0 : inv_zero
... = 0 : mul_zero
theorem div_zero (a : A) : a / 0 = 0 := by rewrite [div_eq_mul_one_div, one_div_zero, mul_zero]
theorem ne_zero_of_one_div_ne_zero (H : 1 / a ≠ 0) : a ≠ 0 :=
assume Ha : a = 0, absurd (Ha⁻¹ ▸ one_div_zero) H
theorem eq_zero_of_one_div_eq_zero (H : 1 / a = 0) : a = 0 :=
decidable.by_cases
(assume Ha, Ha)
(assume Ha, false.elim ((one_div_ne_zero Ha) H))
variables (a b)
theorem one_div_mul_one_div' : (1 / a) * (1 / b) = 1 / (b * a) :=
decidable.by_cases
(suppose a = 0,
by rewrite [this, div_zero, zero_mul, -(@div_zero A s 1), mul_zero b])
(assume Ha : a ≠ 0,
decidable.by_cases
(suppose b = 0,
by rewrite [this, div_zero, mul_zero, -(@div_zero A s 1), zero_mul a])
(suppose b ≠ 0, division_ring.one_div_mul_one_div Ha this))
theorem one_div_neg_eq_neg_one_div : 1 / (- a) = - (1 / a) :=
decidable.by_cases
(suppose a = 0, by rewrite [this, neg_zero, 2 div_zero, neg_zero])
(suppose a ≠ 0, division_ring.one_div_neg_eq_neg_one_div this)
theorem neg_div_neg_eq : (-a) / (-b) = a / b :=
decidable.by_cases
(assume Hb : b = 0, by rewrite [Hb, neg_zero, 2 div_zero])
(assume Hb : b ≠ 0, !division_ring.neg_div_neg_eq Hb)
theorem one_div_one_div : 1 / (1 / a) = a :=
decidable.by_cases
(assume Ha : a = 0, by rewrite [Ha, 2 div_zero])
(assume Ha : a ≠ 0, division_ring.one_div_one_div Ha)
variables {a b}
theorem eq_of_one_div_eq_one_div (H : 1 / a = 1 / b) : a = b :=
decidable.by_cases
(assume Ha : a = 0,
have Hb : b = 0, from eq_zero_of_one_div_eq_zero (by rewrite [-H, Ha, div_zero]),
Hb⁻¹ ▸ Ha)
(assume Ha : a ≠ 0,
have Hb : b ≠ 0, from ne_zero_of_one_div_ne_zero (H ▸ (one_div_ne_zero Ha)),
division_ring.eq_of_one_div_eq_one_div Ha Hb H)
variables (a b)
theorem mul_inv' : (b * a)⁻¹ = a⁻¹ * b⁻¹ :=
decidable.by_cases
(assume Ha : a = 0, by rewrite [Ha, mul_zero, 2 inv_zero, zero_mul])
(assume Ha : a ≠ 0,
decidable.by_cases
(assume Hb : b = 0, by rewrite [Hb, zero_mul, 2 inv_zero, mul_zero])
(assume Hb : b ≠ 0, mul_inv_eq Ha Hb))
-- the following are specifically for fields
theorem one_div_mul_one_div : (1 / a) * (1 / b) = 1 / (a * b) :=
by rewrite [one_div_mul_one_div', mul.comm b]
variable {a}
theorem div_mul_right (Ha : a ≠ 0) : a / (a * b) = 1 / b :=
decidable.by_cases
(assume Hb : b = 0, by rewrite [Hb, mul_zero, 2 div_zero])
(assume Hb : b ≠ 0, field.div_mul_right Hb (mul_ne_zero Ha Hb))
variables (a) {b}
theorem div_mul_left (Hb : b ≠ 0) : b / (a * b) = 1 / a :=
by rewrite [mul.comm a, div_mul_right _ Hb]
variables (a b c)
theorem div_mul_div : (a / b) * (c / d) = (a * c) / (b * d) :=
decidable.by_cases
(assume Hb : b = 0, by rewrite [Hb, div_zero, zero_mul, -(@div_zero A s (a * c)), zero_mul])
(assume Hb : b ≠ 0,
decidable.by_cases
(assume Hd : d = 0, by rewrite [Hd, div_zero, mul_zero, -(@div_zero A s (a * c)),
mul_zero])
(assume Hd : d ≠ 0, !field.div_mul_div Hb Hd))
variable {c}
theorem mul_div_mul_left' (Hc : c ≠ 0) : (c * a) / (c * b) = a / b :=
decidable.by_cases
(assume Hb : b = 0, by rewrite [Hb, mul_zero, 2 div_zero])
(assume Hb : b ≠ 0, !mul_div_mul_left Hb Hc)
theorem mul_div_mul_right' (Hc : c ≠ 0) : (a * c) / (b * c) = a / b :=
by rewrite [(mul.comm a), (mul.comm b), (!mul_div_mul_left' Hc)]
variables (a b c d)
theorem div_mul_eq_mul_div_comm : (b / c) * a = b * (a / c) :=
decidable.by_cases
(assume Hc : c = 0, by rewrite [Hc, div_zero, zero_mul, -(mul_zero b), -(@div_zero A s a)])
(assume Hc : c ≠ 0, !field.div_mul_eq_mul_div_comm Hc)
theorem one_div_div : 1 / (a / b) = b / a :=
decidable.by_cases
(assume Ha : a = 0, by rewrite [Ha, zero_div, 2 div_zero])
(assume Ha : a ≠ 0,
decidable.by_cases
(assume Hb : b = 0, by rewrite [Hb, 2 div_zero, zero_div])
(assume Hb : b ≠ 0, field.one_div_div Ha Hb))
theorem div_div_eq_mul_div : a / (b / c) = (a * c) / b :=
by rewrite [div_eq_mul_one_div, one_div_div, -mul_div_assoc]
theorem div_div_eq_div_mul : (a / b) / c = a / (b * c) :=
by rewrite [div_eq_mul_one_div, div_mul_div, mul_one]
theorem div_div_div_div_eq : (a / b) / (c / d) = (a * d) / (b * c) :=
by rewrite [div_div_eq_mul_div, div_mul_eq_mul_div, div_div_eq_div_mul]
variable {a}
theorem div_helper (H : a ≠ 0) : (1 / (a * b)) * a = 1 / b :=
by rewrite [div_mul_eq_mul_div, one_mul, !div_mul_right H]
variable (a)
theorem div_mul_eq_div_mul_one_div : a / (b * c) = (a / b) * (1 / c) :=
by rewrite [-div_div_eq_div_mul, -div_eq_mul_one_div]
end discrete_field
namespace norm_num
theorem div_add_helper [s : field A] (n d b c val : A) (Hd : d ≠ 0) (H : n + b * d = val)
(H2 : c * d = val) : n / d + b = c :=
begin
apply eq_of_mul_eq_mul_of_nonzero_right Hd,
rewrite [H2, -H, right_distrib, div_mul_cancel _ Hd]
end
theorem add_div_helper [s : field A] (n d b c val : A) (Hd : d ≠ 0) (H : d * b + n = val)
(H2 : d * c = val) : b + n / d = c :=
begin
apply eq_of_mul_eq_mul_of_nonzero_left Hd,
rewrite [H2, -H, left_distrib, mul_div_cancel' Hd]
end
theorem div_mul_helper [s : field A] (n d c v : A) (Hd : d ≠ 0) (H : (n * c) / d = v) :
(n / d) * c = v :=
by rewrite [-H, field.div_mul_eq_mul_div_comm _ _ Hd, mul_div_assoc]
theorem mul_div_helper [s : field A] (a n d v : A) (Hd : d ≠ 0) (H : (a * n) / d = v) :
a * (n / d) = v :=
by rewrite [-H, mul_div_assoc]
theorem nonzero_of_div_helper [s : field A] (a b : A) (Ha : a ≠ 0) (Hb : b ≠ 0) : a / b ≠ 0 :=
begin
intro Hab,
have Habb : (a / b) * b = 0, by rewrite [Hab, zero_mul],
rewrite [div_mul_cancel _ Hb at Habb],
exact Ha Habb
end
theorem div_helper [s : field A] (n d v : A) (Hd : d ≠ 0) (H : v * d = n) : n / d = v :=
begin
apply eq_of_mul_eq_mul_of_nonzero_right Hd,
rewrite (div_mul_cancel _ Hd),
exact eq.symm H
end
theorem div_eq_div_helper [s : field A] (a b c d v : A) (H1 : a * d = v) (H2 : c * b = v)
(Hb : b ≠ 0) (Hd : d ≠ 0) : a / b = c / d :=
begin
apply eq_div_of_mul_eq,
exact Hd,
rewrite div_mul_eq_mul_div,
apply eq.symm,
apply eq_div_of_mul_eq,
exact Hb,
rewrite [H1, H2]
end
theorem subst_into_div [s : has_div A] (a₁ b₁ a₂ b₂ v : A) (H : a₁ / b₁ = v) (H1 : a₂ = a₁)
(H2 : b₂ = b₁) : a₂ / b₂ = v :=
by rewrite [H1, H2, H]
end norm_num
|
7cb03283084e0dc9003d8fa9fa4345e93d8b1e5f | a44280b79dc85615010e3fbda46abf82c6730fa3 | /tests/playground/lazylist.lean | ef32658294b44545da2bd2b08bece81b753a73e9 | [
"Apache-2.0"
] | permissive | kodyvajjha/lean4 | 8e1c613248b531d47367ca6e8d97ee1046645aa1 | c8a045d69fac152fd5e3a577f718615cecb9c53d | refs/heads/master | 1,589,684,450,102 | 1,555,200,447,000 | 1,556,139,945,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 3,912 | lean | /-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
-/
universes u v w
inductive LazyList (α : Type u)
| nil {} : LazyList
| cons (hd : α) (tl : LazyList) : LazyList
| delayed (t : Thunk LazyList) : LazyList
@[extern cpp inline "#2"]
def List.toLazy {α : Type u} : List α → LazyList α
| [] := LazyList.nil
| (h::t) := LazyList.cons h (List.toLazy t)
namespace LazyList
variables {α : Type u} {β : Type v} {δ : Type w}
instance : Inhabited (LazyList α) :=
⟨nil⟩
@[inline] def pure : α → LazyList α
| a := cons a nil
partial def isEmpty : LazyList α → Bool
| nil := true
| (cons _ _) := false
| (delayed as) := isEmpty as.get
partial def toList : LazyList α → List α
| nil := []
| (cons a as) := a :: toList as
| (delayed as) := toList as.get
partial def head [Inhabited α] : LazyList α → α
| nil := default α
| (cons a as) := a
| (delayed as) := head as.get
partial def tail : LazyList α → LazyList α
| nil := nil
| (cons a as) := as
| (delayed as) := tail as.get
partial def append : LazyList α → LazyList α → LazyList α
| nil bs := bs
| (cons a as) bs := delayed (cons a (append as bs))
| (delayed as) bs := delayed (append as.get bs)
instance : HasAppend (LazyList α) :=
⟨LazyList.append⟩
partial def interleave : LazyList α → LazyList α → LazyList α
| nil bs := bs
| (cons a as) bs := delayed (cons a (interleave bs as))
| (delayed as) bs := delayed (interleave as.get bs)
partial def map (f : α → β) : LazyList α → LazyList β
| nil := nil
| (cons a as) := delayed (cons (f a) (map as))
| (delayed as) := delayed (map as.get)
partial def map₂ (f : α → β → δ) : LazyList α → LazyList β → LazyList δ
| nil _ := nil
| _ nil := nil
| (cons a as) (cons b bs) := delayed (cons (f a b) (map₂ as bs))
| (delayed as) bs := delayed (map₂ as.get bs)
| as (delayed bs) := delayed (map₂ as bs.get)
@[inline] def zip : LazyList α → LazyList β → LazyList (α × β) :=
map₂ Prod.mk
partial def join : LazyList (LazyList α) → LazyList α
| nil := nil
| (cons a as) := delayed (append a (join as))
| (delayed as) := delayed (join as.get)
@[inline] partial def bind (x : LazyList α) (f : α → LazyList β) : LazyList β :=
join (x.map f)
instance isMonad : Monad LazyList :=
{ pure := @LazyList.pure, bind := @LazyList.bind, map := @LazyList.map }
instance : Alternative LazyList :=
{ failure := λ _, nil,
orelse := @LazyList.append,
.. LazyList.isMonad }
partial def approx : Nat → LazyList α → List α
| 0 as := []
| _ nil := []
| (i+1) (cons a as) := a :: approx i as
| (i+1) (delayed as) := approx (i+1) as.get
partial def iterate (f : α → α) : α → LazyList α
| x := cons x (delayed (iterate (f x)))
partial def iterate₂ (f : α → α → α) : α → α → LazyList α
| x y := cons x (delayed (iterate₂ y (f x y)))
partial def filter (p : α → Bool) : LazyList α → LazyList α
| nil := nil
| (cons a as) := delayed (if p a then cons a (filter as) else filter as)
| (delayed as) := delayed (filter as.get)
end LazyList
def fib : LazyList Nat :=
LazyList.iterate₂ (+) 0 1
def iota (i : Nat := 0) : LazyList Nat :=
LazyList.iterate Nat.succ i
def tst : LazyList String :=
do x ← [1, 2, 3].toLazy,
y ← [2, 3, 4].toLazy,
guard (x + y > 5),
pure (toString x ++ " + " ++ toString y ++ " = " ++ toString (x+y))
def main : IO Unit :=
do let n := 10,
IO.println $ tst.isEmpty,
IO.println $ tst.head,
IO.println $ (fib.interleave (iota.map (+100))).approx n,
IO.println $ (((iota.map (+10)).filter (λ v, v % 2 == 0)).approx n)
|
07e924fd0b50187b84a4a4f98312868229d45c22 | a0e23cfdd129a671bf3154ee1a8a3a72bf4c7940 | /src/Lean/Elab/BuiltinNotation.lean | a37188cad1db4f7dda14ae6176d055651eb74929 | [
"Apache-2.0"
] | permissive | WojciechKarpiel/lean4 | 7f89706b8e3c1f942b83a2c91a3a00b05da0e65b | f6e1314fa08293dea66a329e05b6c196a0189163 | refs/heads/master | 1,686,633,402,214 | 1,625,821,189,000 | 1,625,821,258,000 | 384,640,886 | 0 | 0 | Apache-2.0 | 1,625,903,617,000 | 1,625,903,026,000 | null | UTF-8 | Lean | false | false | 13,805 | 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 Init.Data.ToString
import Lean.Compiler.BorrowedAnnotation
import Lean.Meta.KAbstract
import Lean.Meta.Transform
import Lean.Elab.Term
import Lean.Elab.SyntheticMVars
namespace Lean.Elab.Term
open Meta
@[builtinTermElab anonymousCtor] def elabAnonymousCtor : TermElab := fun stx expectedType? =>
match stx with
| `(⟨$args,*⟩) => do
tryPostponeIfNoneOrMVar expectedType?
match expectedType? with
| some expectedType =>
let expectedType ← whnf expectedType
matchConstInduct expectedType.getAppFn
(fun _ => throwError "invalid constructor ⟨...⟩, expected type must be an inductive type {indentExpr expectedType}")
(fun ival us => do
match ival.ctors with
| [ctor] =>
let cinfo ← getConstInfoCtor ctor
let numExplicitFields ← forallTelescopeReducing cinfo.type fun xs _ => do
let mut n := 0
for i in [cinfo.numParams:xs.size] do
if (← getFVarLocalDecl xs[i]).binderInfo.isExplicit then
n := n + 1
return n
let args := args.getElems
if args.size < numExplicitFields then
throwError "invalid constructor ⟨...⟩, insufficient number of arguments, constructs '{ctor}' has #{numExplicitFields} explicit fields, but only #{args.size} provided"
let newStx ←
if args.size == numExplicitFields then
`($(mkCIdentFrom stx ctor) $(args)*)
else if numExplicitFields == 0 then
throwError "invalid constructor ⟨...⟩, insufficient number of arguments, constructs '{ctor}' does not have explicit fields, but #{args.size} provided"
else
let extra := args[numExplicitFields-1:args.size]
let newLast ← `(⟨$[$extra],*⟩)
let newArgs := args[0:numExplicitFields-1].toArray.push newLast
`($(mkCIdentFrom stx ctor) $(newArgs)*)
withMacroExpansion stx newStx $ elabTerm newStx expectedType?
| _ => throwError "invalid constructor ⟨...⟩, expected type must be an inductive type with only one constructor {indentExpr expectedType}")
| none => throwError "invalid constructor ⟨...⟩, expected type must be known"
| _ => throwUnsupportedSyntax
@[builtinTermElab borrowed] def elabBorrowed : TermElab := fun stx expectedType? =>
match stx with
| `(@& $e) => return markBorrowed (← elabTerm e expectedType?)
| _ => throwUnsupportedSyntax
@[builtinMacro Lean.Parser.Term.show] def expandShow : Macro := fun stx =>
match stx with
| `(show $type from $val) => let thisId := mkIdentFrom stx `this; `(let_fun $thisId : $type := $val; $thisId)
| `(show $type by%$b $tac:tacticSeq) => `(show $type from by%$b $tac:tacticSeq)
| _ => Macro.throwUnsupported
@[builtinMacro Lean.Parser.Term.have] def expandHave : Macro := fun stx =>
let thisId := mkIdentFrom stx `this
match stx with
| `(have $x $bs* $[: $type]? := $val $[;]? $body) => `(let_fun $x $bs* $[: $type]? := $val; $body)
| `(have $[: $type]? := $val $[;]? $body) => `(have $thisId:ident $[: $type]? := $val; $body)
| `(have $x $bs* $[: $type]? $alts:matchAlts $[;]? $body) => `(let_fun $x $bs* $[: $type]? $alts:matchAlts; $body)
| `(have $[: $type]? $alts:matchAlts $[;]? $body) => `(have $thisId:ident $[: $type]? $alts:matchAlts; $body)
| `(have $pattern:term $[: $type]? := $val:term $[;]? $body) => `(let_fun $pattern:term $[: $type]? := $val:term ; $body)
| _ => Macro.throwUnsupported
@[builtinMacro Lean.Parser.Term.suffices] def expandSuffices : Macro
| `(suffices $[$x :]? $type from $val $[;]? $body) => `(have $[$x]? : $type := $body; $val)
| `(suffices $[$x :]? $type by%$b $tac:tacticSeq $[;]? $body) => `(have $[$x]? : $type := $body; by%$b $tac:tacticSeq)
| _ => Macro.throwUnsupported
open Lean.Parser in
private def elabParserMacroAux (prec : Syntax) (e : Syntax) : TermElabM Syntax := do
let (some declName) ← getDeclName?
| throwError "invalid `leading_parser` macro, it must be used in definitions"
match extractMacroScopes declName with
| { name := Name.str _ s _, scopes := scps, .. } =>
let kind := quote declName
let s := quote s
-- if the parser decl is hidden by hygiene, it doesn't make sense to provide an antiquotation kind
let antiquotKind ← if scps == [] then `(some $kind) else `(none)
``(withAntiquot (mkAntiquot $s $antiquotKind) (leadingNode $kind $prec $e))
| _ => throwError "invalid `leading_parser` macro, unexpected declaration name"
@[builtinTermElab «leading_parser»] def elabLeadingParserMacro : TermElab :=
adaptExpander fun stx => match stx with
| `(leading_parser $e) => elabParserMacroAux (quote Parser.maxPrec) e
| `(leading_parser : $prec $e) => elabParserMacroAux prec e
| _ => throwUnsupportedSyntax
private def elabTParserMacroAux (prec lhsPrec : Syntax) (e : Syntax) : TermElabM Syntax := do
let declName? ← getDeclName?
match declName? with
| some declName => let kind := quote declName; ``(Lean.Parser.trailingNode $kind $prec $lhsPrec $e)
| none => throwError "invalid `trailing_parser` macro, it must be used in definitions"
@[builtinTermElab «trailing_parser»] def elabTrailingParserMacro : TermElab :=
adaptExpander fun stx => match stx with
| `(trailing_parser$[:$prec?]?$[:$lhsPrec?]? $e) =>
elabTParserMacroAux (prec?.getD <| quote Parser.maxPrec) (lhsPrec?.getD <| quote 0) e
| _ => throwUnsupportedSyntax
@[builtinTermElab panic] def elabPanic : TermElab := fun stx expectedType? => do
let arg := stx[1]
let pos ← getRefPosition
let env ← getEnv
let stxNew ← match (← getDeclName?) with
| some declName => `(panicWithPosWithDecl $(quote (toString env.mainModule)) $(quote (toString declName)) $(quote pos.line) $(quote pos.column) $arg)
| none => `(panicWithPos $(quote (toString env.mainModule)) $(quote pos.line) $(quote pos.column) $arg)
withMacroExpansion stx stxNew $ elabTerm stxNew expectedType?
@[builtinMacro Lean.Parser.Term.unreachable] def expandUnreachable : Macro := fun stx =>
`(panic! "unreachable code has been reached")
@[builtinMacro Lean.Parser.Term.assert] def expandAssert : Macro := fun stx =>
-- TODO: support for disabling runtime assertions
let cond := stx[1]
let body := stx[3]
match cond.reprint with
| some code => `(if $cond then $body else panic! ("assertion violation: " ++ $(quote code)))
| none => `(if $cond then $body else panic! ("assertion violation"))
@[builtinMacro Lean.Parser.Term.dbgTrace] def expandDbgTrace : Macro := fun stx =>
let arg := stx[1]
let body := stx[3]
if arg.getKind == interpolatedStrKind then
`(dbgTrace (s! $arg) fun _ => $body)
else
`(dbgTrace (toString $arg) fun _ => $body)
@[builtinTermElab «sorry»] def elabSorry : TermElab := fun stx expectedType? => do
logWarning "declaration uses 'sorry'"
let stxNew ← `(sorryAx _ false)
withMacroExpansion stx stxNew <| elabTerm stxNew expectedType?
/-- Return syntax `Prod.mk elems[0] (Prod.mk elems[1] ... (Prod.mk elems[elems.size - 2] elems[elems.size - 1])))` -/
partial def mkPairs (elems : Array Syntax) : MacroM Syntax :=
let rec loop (i : Nat) (acc : Syntax) := do
if i > 0 then
let i := i - 1
let elem := elems[i]
let acc ← `(Prod.mk $elem $acc)
loop i acc
else
pure acc
loop (elems.size - 1) elems.back
private partial def hasCDot : Syntax → Bool
| Syntax.node k args =>
if k == `Lean.Parser.Term.paren then false
else if k == `Lean.Parser.Term.cdot then true
else args.any hasCDot
| _ => false
/--
Return `some` if succeeded expanding `·` notation occurring in
the given syntax. Otherwise, return `none`.
Examples:
- `· + 1` => `fun _a_1 => _a_1 + 1`
- `f · · b` => `fun _a_1 _a_2 => f _a_1 _a_2 b` -/
partial def expandCDot? (stx : Syntax) : MacroM (Option Syntax) := do
if hasCDot stx then
let (newStx, binders) ← (go stx).run #[];
`(fun $binders* => $newStx)
else
pure none
where
/--
Auxiliary function for expanding the `·` notation.
The extra state `Array Syntax` contains the new binder names.
If `stx` is a `·`, we create a fresh identifier, store in the
extra state, and return it. Otherwise, we just return `stx`. -/
go : Syntax → StateT (Array Syntax) MacroM Syntax
| stx@(Syntax.node k args) =>
if k == `Lean.Parser.Term.paren then pure stx
else if k == `Lean.Parser.Term.cdot then withFreshMacroScope do
let id ← `(a)
modify fun s => s.push id;
pure id
else do
let args ← args.mapM go
pure $ Syntax.node k args
| stx => pure stx
/--
Helper method for elaborating terms such as `(.+.)` where a constant name is expected.
This method is usually used to implement tactics that function names as arguments (e.g., `simp`).
-/
def elabCDotFunctionAlias? (stx : Syntax) : TermElabM (Option Expr) := do
let some stx ← liftMacroM <| expandCDotArg? stx | pure none
let stx ← liftMacroM <| expandMacros stx
match stx with
| `(fun $binders* => $f:ident $args*) =>
if binders == args then
try Term.resolveId? f catch _ => return none
else
return none
| `(fun $binders* => binop% $f:ident $a $b) =>
if binders == #[a, b] then
try Term.resolveId? f catch _ => return none
else
return none
| _ => return none
where
expandCDotArg? (stx : Syntax) : MacroM (Option Syntax) :=
match stx with
| `(($e)) => Term.expandCDot? e
| _ => Term.expandCDot? stx
/--
Try to expand `·` notation.
Recall that in Lean the `·` notation must be surrounded by parentheses.
We may change this is the future, but right now, here are valid examples
- `(· + 1)`
- `(f ⟨·, 1⟩ ·)`
- `(· + ·)`
- `(f · a b)` -/
@[builtinMacro Lean.Parser.Term.paren] def expandParen : Macro
| `(()) => `(Unit.unit)
| `(($e : $type)) => do
match (← expandCDot? e) with
| some e => `(($e : $type))
| none => Macro.throwUnsupported
| `(($e)) => return (← expandCDot? e).getD e
| `(($e, $es,*)) => do
let pairs ← mkPairs (#[e] ++ es)
(← expandCDot? pairs).getD pairs
| stx =>
if !stx[1][0].isMissing && stx[1][1].isMissing then
-- parsed `(` and `term`, assume it's a basic parenthesis to get any elaboration output at all
`(($(stx[1][0])))
else
throw <| Macro.Exception.error stx "unexpected parentheses notation"
@[builtinTermElab paren] def elabParen : TermElab := fun stx expectedType? => do
match stx with
| `(($e : $type)) =>
let type ← withSynthesize (mayPostpone := true) <| elabType type
let e ← elabTerm e type
ensureHasType type e
| _ => throwUnsupportedSyntax
@[builtinTermElab subst] def elabSubst : TermElab := fun stx expectedType? => do
let expectedType ← tryPostponeIfHasMVars expectedType? "invalid `▸` notation"
match stx with
| `($heq ▸ $h) => do
let mut heq ← elabTerm heq none
let heqType ← inferType heq
let heqType ← instantiateMVars heqType
match (← Meta.matchEq? heqType) with
| none => throwError "invalid `▸` notation, argument{indentExpr heq}\nhas type{indentExpr heqType}\nequality expected"
| some (α, lhs, rhs) =>
let mut lhs := lhs
let mut rhs := rhs
let mkMotive (typeWithLooseBVar : Expr) := do
withLocalDeclD (← mkFreshUserName `x) α fun x => do
mkLambdaFVars #[x] $ typeWithLooseBVar.instantiate1 x
let mut expectedAbst ← kabstract expectedType rhs
unless expectedAbst.hasLooseBVars do
expectedAbst ← kabstract expectedType lhs
unless expectedAbst.hasLooseBVars do
throwError "invalid `▸` notation, expected type{indentExpr expectedType}\ndoes contain equation left-hand-side nor right-hand-side{indentExpr heqType}"
heq ← mkEqSymm heq
(lhs, rhs) := (rhs, lhs)
let hExpectedType := expectedAbst.instantiate1 lhs
let h ← withRef h do
let h ← elabTerm h hExpectedType
try
ensureHasType hExpectedType h
catch ex =>
-- if `rhs` occurs in `hType`, we try to apply `heq` to `h` too
let hType ← inferType h
let hTypeAbst ← kabstract hType rhs
unless hTypeAbst.hasLooseBVars do
throw ex
let hTypeNew := hTypeAbst.instantiate1 lhs
unless (← isDefEq hExpectedType hTypeNew) do
throw ex
mkEqNDRec (← mkMotive hTypeAbst) h (← mkEqSymm heq)
mkEqNDRec (← mkMotive expectedAbst) h heq
| _ => throwUnsupportedSyntax
@[builtinTermElab stateRefT] def elabStateRefT : TermElab := fun stx _ => do
let σ ← elabType stx[1]
let mut mStx := stx[2]
if mStx.getKind == `Lean.Parser.Term.macroDollarArg then
mStx := mStx[1]
let m ← elabTerm mStx (← mkArrow (mkSort levelOne) (mkSort levelOne))
let ω ← mkFreshExprMVar (mkSort levelOne)
let stWorld ← mkAppM `STWorld #[ω, m]
discard <| mkInstMVar stWorld
mkAppM `StateRefT' #[ω, σ, m]
@[builtinTermElab noindex] def elabNoindex : TermElab := fun stx expectedType? => do
let e ← elabTerm stx[1] expectedType?
return DiscrTree.mkNoindexAnnotation e
end Lean.Elab.Term
|
a665bd41168579a962dd6ff40f5afcc56a725b34 | 05b503addd423dd68145d68b8cde5cd595d74365 | /src/group_theory/congruence.lean | b22c7d385bfabadd6cf56be34b0fd0877b4a69bd | [
"Apache-2.0"
] | permissive | aestriplex/mathlib | 77513ff2b176d74a3bec114f33b519069788811d | e2fa8b2b1b732d7c25119229e3cdfba8370cb00f | refs/heads/master | 1,621,969,960,692 | 1,586,279,279,000 | 1,586,279,279,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 43,494 | 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.submonoid
import data.setoid
import algebra.pi_instances
/-!
# Congruence relations
This file defines congruence relations: equivalence relations that preserve a binary operation,
which in this case is multiplication or addition. The principal definition is a `structure`
extending a `setoid` (an equivalence relation), and the inductive definition of the smallest
congruence relation containing a binary relation is also given (see `con_gen`).
The file also proves basic properties of the quotient of a type by a congruence relation, and the
complete lattice of congruence relations on a type. We then establish an order-preserving bijection
between the set of congruence relations containing a congruence relation `c` and the set of
congruence relations on the quotient by `c`.
The second half of the file concerns congruence relations on monoids, in which case the
quotient by the congruence relation is also a monoid. There are results about the universal
property of quotients of monoids, and the isomorphism theorems for monoids.
## Implementation notes
The inductive definition of a congruence relation could be a nested inductive type, defined using
the equivalence closure of a binary relation `eqv_gen`, but the recursor generated does not work.
A nested inductive definition could conceivably shorten proofs, because they would allow invocation
of the corresponding lemmas about `eqv_gen`.
The lemmas `refl`, `symm` and `trans` are not tagged with `@[refl]`, `@[symm]`, and `@[trans]`
respectively as these tags do not work on a structure coerced to a binary relation.
There is a coercion from elements of a type to the element's equivalence class under a
congruence relation.
A congruence relation on a monoid `M` can be thought of as a submonoid of `M × M` for which
membership is an equivalence relation, but whilst this fact is established in the file, it is not
used, since this perspective adds more layers of definitional unfolding.
## Tags
congruence, congruence relation, quotient, quotient by congruence relation, monoid,
quotient monoid, isomorphism theorems
-/
variables (M : Type*) {N : Type*} {P : Type*}
set_option old_structure_cmd true
open function setoid
/-- A congruence relation on a type with an addition is an equivalence relation which
preserves addition. -/
structure add_con [has_add M] extends setoid M :=
(add' : ∀ {w x y z}, r w x → r y z → r (w + y) (x + z))
/-- A congruence relation on a type with a multiplication is an equivalence relation which
preserves multiplication. -/
@[to_additive add_con] structure con [has_mul M] extends setoid M :=
(mul' : ∀ {w x y z}, r w x → r y z → r (w * y) (x * z))
variables {M}
/-- The inductively defined smallest additive congruence relation containing a given binary
relation. -/
inductive add_con_gen.rel [has_add M] (r : M → M → Prop) : M → M → Prop
| of {} : Π x y, r x y → add_con_gen.rel x y
| refl {} : Π x, add_con_gen.rel x x
| symm {} : Π x y, add_con_gen.rel x y → add_con_gen.rel y x
| trans {} : Π x y z, add_con_gen.rel x y → add_con_gen.rel y z → add_con_gen.rel x z
| add {} : Π w x y z, add_con_gen.rel w x → add_con_gen.rel y z → add_con_gen.rel (w + y) (x + z)
/-- The inductively defined smallest multiplicative congruence relation containing a given binary
relation. -/
@[to_additive add_con_gen.rel]
inductive con_gen.rel [has_mul M] (r : M → M → Prop) : M → M → Prop
| of {} : Π x y, r x y → con_gen.rel x y
| refl {} : Π x, con_gen.rel x x
| symm {} : Π x y, con_gen.rel x y → con_gen.rel y x
| trans {} : Π x y z, con_gen.rel x y → con_gen.rel y z → con_gen.rel x z
| mul {} : Π w x y z, con_gen.rel w x → con_gen.rel y z → con_gen.rel (w * y) (x * z)
/-- The inductively defined smallest multiplicative congruence relation containing a given binary
relation. -/
@[to_additive add_con_gen "The inductively defined smallest additive congruence relation containing a given binary relation."]
def con_gen [has_mul M] (r : M → M → Prop) : con M :=
⟨con_gen.rel r, ⟨con_gen.rel.refl, con_gen.rel.symm, con_gen.rel.trans⟩, con_gen.rel.mul⟩
namespace con
section
variables [has_mul M] [has_mul N] [has_mul P] (c : con M)
@[to_additive]
instance : inhabited (con M) :=
⟨con_gen empty_relation⟩
/-- A coercion from a congruence relation to its underlying binary relation. -/
@[to_additive "A coercion from an additive congruence relation to its underlying binary relation."]
instance : has_coe_to_fun (con M) := ⟨_, λ c, λ x y, c.r x y⟩
/-- Congruence relations are reflexive. -/
@[to_additive "Additive congruence relations are reflexive."]
protected lemma refl (x) : c x x := c.2.1 x
/-- Congruence relations are symmetric. -/
@[to_additive "Additive congruence relations are symmetric."]
protected lemma symm : ∀ {x y}, c x y → c y x := λ _ _ h, c.2.2.1 h
/-- Congruence relations are transitive. -/
@[to_additive "Additive congruence relations are transitive."]
protected lemma trans : ∀ {x y z}, c x y → c y z → c x z :=
λ _ _ _ h, c.2.2.2 h
/-- Multiplicative congruence relations preserve multiplication. -/
@[to_additive "Additive congruence relations preserve addition."]
protected lemma mul : ∀ {w x y z}, c w x → c y z → c (w * y) (x * z) :=
λ _ _ _ _ h1 h2, c.3 h1 h2
/-- Given a type `M` with a multiplication, a congruence relation `c` on `M`, and elements of `M`
`x, y`, `(x, y) ∈ M × M` iff `x` is related to `y` by `c`. -/
@[to_additive "Given a type `M` with an addition, `x, y ∈ M`, and an additive congruence relation `c` on `M`, `(x, y) ∈ M × M` iff `x` is related to `y` by `c`."]
instance : has_mem (M × M) (con M) := ⟨λ x c, c x.1 x.2⟩
variables {c}
/-- The map sending a congruence relation to its underlying binary relation is injective. -/
@[to_additive "The map sending an additive congruence relation to its underlying binary relation is injective."]
lemma ext' {c d : con M} (H : c.r = d.r) : c = d :=
by cases c; cases d; simpa using H
/-- Extensionality rule for congruence relations. -/
@[ext, to_additive "Extensionality rule for additive congruence relations."]
lemma ext {c d : con M} (H : ∀ x y, c x y ↔ d x y) : c = d :=
ext' $ by ext; apply H
attribute [ext] add_con.ext
/-- The map sending a congruence relation to its underlying equivalence relation is injective. -/
@[to_additive "The map sending an additive congruence relation to its underlying equivalence relation is injective."]
lemma to_setoid_inj {c d : con M} (H : c.to_setoid = d.to_setoid) : c = d :=
ext $ ext_iff.1 H
/-- Iff version of extensionality rule for congruence relations. -/
@[to_additive "Iff version of extensionality rule for additive congruence relations."]
lemma ext_iff {c d : con M} : (∀ x y, c x y ↔ d x y) ↔ c = d :=
⟨ext, λ h _ _, h ▸ iff.rfl⟩
/-- Two congruence relations are equal iff their underlying binary relations are equal. -/
@[to_additive "Two additive congruence relations are equal iff their underlying binary relations are equal."]
lemma ext'_iff {c d : con M} : c.r = d.r ↔ c = d :=
⟨ext', λ h, h ▸ rfl⟩
/-- The kernel of a multiplication-preserving function as a congruence relation. -/
@[to_additive "The kernel of an addition-preserving function as an additive congruence relation."]
def mul_ker (f : M → P) (h : ∀ x y, f (x * y) = f x * f y) : con M :=
{ r := λ x y, f x = f y,
iseqv := ⟨λ _, rfl, λ _ _, eq.symm, λ _ _ _, eq.trans⟩,
mul' := λ _ _ _ _ h1 h2, by rw [h, h1, h2, h] }
/-- Given types with multiplications `M, N`, the product of two congruence relations `c` on `M` and
`d` on `N`: `(x₁, x₂), (y₁, y₂) ∈ M × N` are related by `c.prod d` iff `x₁` is related to `y₁`
by `c` and `x₂` is related to `y₂` by `d`. -/
@[to_additive prod "Given types with additions `M, N`, the product of two congruence relations `c` on `M` and `d` on `N`: `(x₁, x₂), (y₁, y₂) ∈ M × N` are related by `c.prod d` iff `x₁` is related to `y₁` by `c` and `x₂` is related to `y₂` by `d`."]
protected def prod (c : con M) (d : con N) : con (M × N) :=
{ mul' := λ _ _ _ _ h1 h2, ⟨c.mul h1.1 h2.1, d.mul h1.2 h2.2⟩, ..c.to_setoid.prod d.to_setoid }
/-- The product of an indexed collection of congruence relations. -/
@[to_additive "The product of an indexed collection of additive congruence relations."]
def pi {ι : Type*} {f : ι → Type*} [Π i, has_mul (f i)]
(C : Π i, con (f i)) : con (Π i, f i) :=
{ mul' := λ _ _ _ _ h1 h2 i, (C i).mul (h1 i) (h2 i), ..@pi_setoid _ _ $ λ i, (C i).to_setoid }
variables (c)
@[simp, to_additive] lemma coe_eq : c.to_setoid.r = c := rfl
-- Quotients
/-- Defining the quotient by a congruence relation of a type with a multiplication. -/
@[to_additive "Defining the quotient by an additive congruence relation of a type with an addition."]
protected def quotient := quotient $ c.to_setoid
/-- Coercion from a type with a multiplication to its quotient by a congruence relation.
See Note [use has_coe_t]. -/
@[to_additive "Coercion from a type with an addition to its quotient by an additive congruence relation", priority 0]
instance : has_coe_t M c.quotient := ⟨@quotient.mk _ c.to_setoid⟩
/-- The quotient of a type with decidable equality by a congruence relation also has
decidable equality. -/
@[to_additive "The quotient of a type with decidable equality by an additive congruence relation also has decidable equality."]
instance [d : ∀ a b, decidable (c a b)] : decidable_eq c.quotient :=
@quotient.decidable_eq M c.to_setoid d
/-- The function on the quotient by a congruence relation `c` induced by a function that is
constant on `c`'s equivalence classes. -/
@[elab_as_eliminator, to_additive "The function on the quotient by a congruence relation `c` induced by a function that is constant on `c`'s equivalence classes."]
protected def lift_on {β} {c : con M} (q : c.quotient) (f : M → β)
(h : ∀ a b, c a b → f a = f b) : β := quotient.lift_on' q f h
variables {c}
/-- The inductive principle used to prove propositions about the elements of a quotient by a
congruence relation. -/
@[elab_as_eliminator, to_additive "The inductive principle used to prove propositions about the elements of a quotient by an additive congruence relation."]
protected lemma induction_on {C : c.quotient → Prop} (q : c.quotient) (H : ∀ x : M, C x) : C q :=
quotient.induction_on' q H
/-- A version of `con.induction_on` for predicates which take two arguments. -/
@[elab_as_eliminator, to_additive "A version of `add_con.induction_on` for predicates which take two arguments."]
protected lemma induction_on₂ {d : con N} {C : c.quotient → d.quotient → Prop}
(p : c.quotient) (q : d.quotient) (H : ∀ (x : M) (y : N), C x y) : C p q :=
quotient.induction_on₂' p q H
variables (c)
/-- Two elements are related by a congruence relation `c` iff they are represented by the same
element of the quotient by `c`. -/
@[simp, to_additive "Two elements are related by an additive congruence relation `c` iff they are represented by the same element of the quotient by `c`."]
protected lemma eq {a b : M} : (a : c.quotient) = b ↔ c a b :=
quotient.eq'
/-- The multiplication induced on the quotient by a congruence relation on a type with a
multiplication. -/
@[to_additive "The addition induced on the quotient by an additive congruence relation on a type with a addition."]
instance has_mul : has_mul c.quotient :=
⟨λ x y, quotient.lift_on₂' x y (λ w z, ((w * z : M) : c.quotient))
$ λ _ _ _ _ h1 h2, c.eq.2 $ c.mul h1 h2⟩
/-- The kernel of the quotient map induced by a congruence relation `c` equals `c`. -/
@[simp, to_additive "The kernel of the quotient map induced by an additive congruence relation `c` equals `c`."]
lemma mul_ker_mk_eq : mul_ker (coe : M → c.quotient) (λ x y, rfl) = c :=
ext $ λ x y, quotient.eq'
variables {c}
/-- The coercion to the quotient of a congruence relation commutes with multiplication (by
definition). -/
@[simp, to_additive "The coercion to the quotient of an additive congruence relation commutes with addition (by definition)."]
lemma coe_mul (x y : M) : (↑(x * y) : c.quotient) = ↑x * ↑y := rfl
/-- Definition of the function on the quotient by a congruence relation `c` induced by a function
that is constant on `c`'s equivalence classes. -/
@[simp, to_additive "Definition of the function on the quotient by an additive congruence relation `c` induced by a function that is constant on `c`'s equivalence classes."]
protected lemma lift_on_beta {β} (c : con M) (f : M → β)
(h : ∀ a b, c a b → f a = f b) (x : M) :
con.lift_on (x : c.quotient) f h = f x := rfl
/-- Makes an isomorphism of quotients by two congruence relations, given that the relations are
equal. -/
@[to_additive "Makes an additive isomorphism of quotients by two additive congruence relations, given that the relations are equal."]
protected def congr {c d : con M} (h : c = d) : c.quotient ≃* d.quotient :=
{ map_mul' := λ x y, by rcases x; rcases y; refl,
..quotient.congr (equiv.refl M) $ by apply ext_iff.2 h }
-- The complete lattice of congruence relations on a type
/-- For congruence relations `c, d` on a type `M` with a multiplication, `c ≤ d` iff `∀ x y ∈ M`,
`x` is related to `y` by `d` if `x` is related to `y` by `c`. -/
@[to_additive "For additive congruence relations `c, d` on a type `M` with an addition, `c ≤ d` iff `∀ x y ∈ M`, `x` is related to `y` by `d` if `x` is related to `y` by `c`."]
instance : has_le (con M) := ⟨λ c d, c.to_setoid ≤ d.to_setoid⟩
/-- Definition of `≤` for congruence relations. -/
@[to_additive "Definition of `≤` for additive congruence relations."]
theorem le_def {c d : con M} : c ≤ d ↔ ∀ {x y}, c x y → d x y := iff.rfl
/-- The infimum of a set of congruence relations on a given type with a multiplication. -/
@[to_additive "The infimum of a set of additive congruence relations on a given type with an addition."]
instance : has_Inf (con M) :=
⟨λ S, ⟨λ x y, ∀ c : con M, c ∈ S → c x y,
⟨λ x c hc, c.refl x, λ _ _ h c hc, c.symm $ h c hc,
λ _ _ _ h1 h2 c hc, c.trans (h1 c hc) $ h2 c hc⟩,
λ _ _ _ _ h1 h2 c hc, c.mul (h1 c hc) $ h2 c hc⟩⟩
/-- The infimum of a set of congruence relations is the same as the infimum of the set's image
under the map to the underlying equivalence relation. -/
@[to_additive "The infimum of a set of additive congruence relations is the same as the infimum of the set's image under the map to the underlying equivalence relation."]
lemma Inf_to_setoid (S : set (con M)) : (Inf S).to_setoid = Inf (to_setoid '' S) :=
setoid.ext' $ λ x y, ⟨λ h r ⟨c, hS, hr⟩, by rw ←hr; exact h c hS,
λ h c hS, h c.to_setoid ⟨c, hS, rfl⟩⟩
/-- The infimum of a set of congruence relations is the same as the infimum of the set's image
under the map to the underlying binary relation. -/
@[to_additive "The infimum of a set of additive congruence relations is the same as the infimum of the set's image under the map to the underlying binary relation."]
lemma Inf_def (S : set (con M)) : (Inf S).r = Inf (r '' S) :=
by { ext, simp only [Inf_image, infi_apply, infi_Prop_eq], refl }
/-- If a congruence relation `c` is contained in every element of a set `s` of congruence relations
on the same type, `c` is contained in the infimum of `s`. -/
@[to_additive "If an additive congruence relation `c` is contained in every element of a set `s` of additive congruence relations on the same type, `c` is contained in the infimum of `s`."]
lemma le_Inf (s : set (con M)) (c) : (∀d ∈ s, c ≤ d) → c ≤ Inf s :=
λ h _ _ hc r hr, h r hr _ _ hc
/-- The infimum of a set of congruence relations on a given type is contained in every element
of the set. -/
@[to_additive "The infimum of a set of additive congruence relations on a given type is contained in every element of the set."]
lemma Inf_le (s : set (con M)) (c) : c ∈ s → Inf s ≤ c :=
λ hc _ _ h, h c hc
/-- The complete lattice of congruence relations on a given type with a multiplication. -/
@[to_additive "The complete lattice of additive congruence relations on a given type with an addition."]
instance : complete_lattice (con M) :=
{ sup := λ c d, Inf { x | c ≤ x ∧ d ≤ x},
le := (≤),
lt := λ c d, c ≤ d ∧ ¬d ≤ c,
le_refl := λ c _ _, id,
le_trans := λ c1 c2 c3 h1 h2 x y h, h2 x y $ h1 x y h,
lt_iff_le_not_le := λ _ _, iff.rfl,
le_antisymm := λ c d hc hd, ext $ λ x y, ⟨hc x y, hd x y⟩,
le_sup_left := λ _ _ _ _ h r hr, hr.1 _ _ h,
le_sup_right := λ _ _ _ _ h r hr, hr.2 _ _ h,
sup_le := λ _ _ c h1 h2, Inf_le _ c ⟨h1, h2⟩,
inf := λ c d, ⟨(c.to_setoid ⊓ d.to_setoid).1, (c.to_setoid ⊓ d.to_setoid).2,
λ _ _ _ _ h1 h2, ⟨c.mul h1.1 h2.1, d.mul h1.2 h2.2⟩⟩,
inf_le_left := λ _ _ _ _ h, h.1,
inf_le_right := λ _ _ _ _ h, h.2,
le_inf := λ _ _ _ hb hc _ _ h, ⟨hb _ _ h, hc _ _ h⟩,
top := { mul' := by tauto, ..setoid.complete_lattice.top},
le_top := λ _ _ _ h, trivial,
bot := { mul' := λ _ _ _ _ h1 h2, h1 ▸ h2 ▸ rfl, ..setoid.complete_lattice.bot},
bot_le := λ c x y h, h ▸ c.refl x,
Sup := λ tt, Inf {t | ∀t'∈tt, t' ≤ t},
Inf := has_Inf.Inf,
le_Sup := λ _ _ hs, le_Inf _ _ $ λ c' hc', hc' _ hs,
Sup_le := λ _ _ hs, Inf_le _ _ hs,
Inf_le := λ _ _, Inf_le _ _,
le_Inf := λ _ _, le_Inf _ _ }
/-- The infimum of two congruence relations equals the infimum of the underlying binary
operations. -/
@[to_additive "The infimum of two additive congruence relations equals the infimum of the underlying binary operations."]
lemma inf_def {c d : con M} : (c ⊓ d).r = c.r ⊓ d.r := rfl
/-- Definition of the infimum of two congruence relations. -/
@[to_additive "Definition of the infimum of two additive congruence relations."]
theorem inf_iff_and {c d : con M} {x y} : (c ⊓ d) x y ↔ c x y ∧ d x y := iff.rfl
/-- The inductively defined smallest congruence relation containing a binary relation `r` equals
the infimum of the set of congruence relations containing `r`. -/
@[to_additive add_con_gen_eq "The inductively defined smallest additive congruence relation containing a binary relation `r` equals the infimum of the set of additive congruence relations containing `r`."]
theorem con_gen_eq (r : M → M → Prop) :
con_gen r = Inf {s : con M | ∀ x y, r x y → s.r x y} :=
ext $ λ x y,
⟨λ H, con_gen.rel.rec_on H (λ _ _ h _ hs, hs _ _ h) (con.refl _) (λ _ _ _, con.symm _)
(λ _ _ _ _ _, con.trans _)
$ λ w x y z _ _ h1 h2 c hc, c.mul (h1 c hc) $ h2 c hc,
Inf_le _ _ (λ _ _, con_gen.rel.of _ _) _ _⟩
/-- The smallest congruence relation containing a binary relation `r` is contained in any
congruence relation containing `r`. -/
@[to_additive add_con_gen_le "The smallest additive congruence relation containing a binary relation `r` is contained in any additive congruence relation containing `r`."]
theorem con_gen_le {r : M → M → Prop} {c : con M} (h : ∀ x y, r x y → c.r x y) :
con_gen r ≤ c :=
by rw con_gen_eq; exact Inf_le _ _ h
/-- Given binary relations `r, s` with `r` contained in `s`, the smallest congruence relation
containing `s` contains the smallest congruence relation containing `r`. -/
@[to_additive add_con_gen_mono "Given binary relations `r, s` with `r` contained in `s`, the smallest additive congruence relation containing `s` contains the smallest additive congruence relation containing `r`."]
theorem con_gen_mono {r s : M → M → Prop} (h : ∀ x y, r x y → s x y) :
con_gen r ≤ con_gen s :=
con_gen_le $ λ x y hr, con_gen.rel.of _ _ $ h x y hr
/-- Congruence relations equal the smallest congruence relation in which they are contained. -/
@[simp, to_additive add_con_gen_of_add_con "Additive congruence relations equal the smallest additive congruence relation in which they are contained."]
lemma con_gen_of_con (c : con M) : con_gen c.r = c :=
le_antisymm (by rw con_gen_eq; exact Inf_le _ c (λ _ _, id)) con_gen.rel.of
/-- The map sending a binary relation to the smallest congruence relation in which it is
contained is idempotent. -/
@[simp, to_additive add_con_gen_idem "The map sending a binary relation to the smallest additive congruence relation in which it is contained is idempotent."]
lemma con_gen_idem (r : M → M → Prop) :
con_gen (con_gen r).r = con_gen r :=
con_gen_of_con _
/-- The supremum of congruence relations `c, d` equals the smallest congruence relation containing
the binary relation '`x` is related to `y` by `c` or `d`'. -/
@[to_additive sup_eq_add_con_gen "The supremum of additive congruence relations `c, d` equals the smallest additive congruence relation containing the binary relation '`x` is related to `y` by `c` or `d`'."]
lemma sup_eq_con_gen (c d : con M) :
c ⊔ d = con_gen (λ x y, c x y ∨ d x y) :=
begin
rw con_gen_eq,
apply congr_arg Inf,
ext,
exact ⟨λ h _ _ H, or.elim H (h.1 _ _) (h.2 _ _),
λ H, ⟨λ _ _ h, H _ _ $ or.inl h, λ _ _ h, H _ _ $ or.inr h⟩⟩,
end
/-- The supremum of two congruence relations equals the smallest congruence relation containing
the supremum of the underlying binary operations. -/
@[to_additive "The supremum of two additive congruence relations equals the smallest additive congruence relation containing the supremum of the underlying binary operations."]
lemma sup_def {c d : con M} : c ⊔ d = con_gen (c.r ⊔ d.r) :=
by rw sup_eq_con_gen; refl
/-- The supremum of a set of congruence relations `S` equals the smallest congruence relation
containing the binary relation 'there exists `c ∈ S` such that `x` is related to `y` by
`c`'. -/
@[to_additive Sup_eq_add_con_gen "The supremum of a set of additive congruence relations S equals the smallest additive congruence relation containing the binary relation 'there exists `c ∈ S` such that `x` is related to `y` by `c`'."]
lemma Sup_eq_con_gen (S : set (con M)) :
Sup S = con_gen (λ x y, ∃ c : con M, c ∈ S ∧ c x y) :=
begin
rw con_gen_eq,
apply congr_arg Inf,
ext,
exact ⟨λ h _ _ ⟨r, hr⟩, h r hr.1 _ _ hr.2,
λ h r hS _ _ hr, h _ _ ⟨r, hS, hr⟩⟩,
end
/-- The supremum of a set of congruence relations is the same as the smallest congruence relation
containing the supremum of the set's image under the map to the underlying binary relation. -/
@[to_additive "The supremum of a set of additive congruence relations is the same as the smallest additive congruence relation containing the supremum of the set's image under the map to the underlying binary relation."]
lemma Sup_def {S : set (con M)} : Sup S = con_gen (Sup (r '' S)) :=
begin
rw Sup_eq_con_gen,
congr,
ext x y,
erw [Sup_image, supr_apply, supr_apply, supr_Prop_eq],
simp only [Sup_image, supr_Prop_eq, supr_apply, supr_Prop_eq, exists_prop],
refl,
end
variables (M)
/-- There is a Galois insertion of congruence relations on a type with a multiplication `M` into
binary relations on `M`. -/
@[to_additive "There is a Galois insertion of additive congruence relations on a type with an addition `M` into binary relations on `M`."]
protected def gi : @galois_insertion (M → M → Prop) (con M) _ _ con_gen r :=
{ choice := λ r h, con_gen r,
gc := λ r c, ⟨λ H _ _ h, H _ _ $ con_gen.rel.of _ _ h, λ H, con_gen_of_con c ▸ con_gen_mono H⟩,
le_l_u := λ x, (con_gen_of_con x).symm ▸ le_refl x,
choice_eq := λ _ _, rfl }
variables {M} (c)
/-- Given a function `f`, the smallest congruence relation containing the binary relation on `f`'s
image defined by '`x ≈ y` iff the elements of `f⁻¹(x)` are related to the elements of `f⁻¹(y)`
by a congruence relation `c`.' -/
@[to_additive "Given a function `f`, the smallest additive congruence relation containing the binary relation on `f`'s image defined by '`x ≈ y` iff the elements of `f⁻¹(x)` are related to the elements of `f⁻¹(y)` by an additive congruence relation `c`.'"]
def map_gen (f : M → N) : con N :=
con_gen $ λ x y, ∃ a b, f a = x ∧ f b = y ∧ c a b
/-- Given a surjective multiplicative-preserving function `f` whose kernel is contained in a
congruence relation `c`, the congruence relation on `f`'s codomain defined by '`x ≈ y` iff the
elements of `f⁻¹(x)` are related to the elements of `f⁻¹(y)` by `c`.' -/
@[to_additive "Given a surjective addition-preserving function `f` whose kernel is contained in an additive congruence relation `c`, the additive congruence relation on `f`'s codomain defined by '`x ≈ y` iff the elements of `f⁻¹(x)` are related to the elements of `f⁻¹(y)` by `c`.'"]
def map_of_surjective (f : M → N) (H : ∀ x y, f (x * y) = f x * f y) (h : mul_ker f H ≤ c)
(hf : surjective f) : con N :=
{ mul' := λ w x y z ⟨a, b, hw, hx, h1⟩ ⟨p, q, hy, hz, h2⟩,
⟨a * p, b * q, by rw [H, hw, hy], by rw [H, hx, hz], c.mul h1 h2⟩,
..c.to_setoid.map_of_surjective f h hf }
/-- A specialization of 'the smallest congruence relation containing a congruence relation `c`
equals `c`'. -/
@[to_additive "A specialization of 'the smallest additive congruence relation containing an additive congruence relation `c` equals `c`'."]
lemma map_of_surjective_eq_map_gen {c : con M} {f : M → N} (H : ∀ x y, f (x * y) = f x * f y)
(h : mul_ker f H ≤ c) (hf : surjective f) :
c.map_gen f = c.map_of_surjective f H h hf :=
by rw ←con_gen_of_con (c.map_of_surjective f H h hf); refl
/-- Given types with multiplications `M, N` and a congruence relation `c` on `N`, a
multiplication-preserving map `f : M → N` induces a congruence relation on `f`'s domain
defined by '`x ≈ y` iff `f(x)` is related to `f(y)` by `c`.' -/
@[to_additive "Given types with additions `M, N` and an additive congruence relation `c` on `N`, an addition-preserving map `f : M → N` induces an additive congruence relation on `f`'s domain defined by '`x ≈ y` iff `f(x)` is related to `f(y)` by `c`.' "]
def comap (f : M → N) (H : ∀ x y, f (x * y) = f x * f y) (c : con N) : con M :=
{ mul' := λ w x y z h1 h2, show c (f (w * y)) (f (x * z)), by rw [H, H]; exact c.mul h1 h2,
..c.to_setoid.comap f }
section
open quotient
/-- Given a congruence relation `c` on a type `M` with a multiplication, the order-preserving
bijection between the set of congruence relations containing `c` and the congruence relations
on the quotient of `M` by `c`. -/
@[to_additive "Given an additive congruence relation `c` on a type `M` with an addition, the order-preserving bijection between the set of additive congruence relations containing `c` and the additive congruence relations on the quotient of `M` by `c`."]
def correspondence : ((≤) : {d // c ≤ d} → {d // c ≤ d} → Prop) ≃o
((≤) : con c.quotient → con c.quotient → Prop) :=
{ to_fun := λ d, d.1.map_of_surjective coe _
(by rw mul_ker_mk_eq; exact d.2) $ @exists_rep _ c.to_setoid,
inv_fun := λ d, ⟨comap (coe : M → c.quotient) (λ x y, rfl) d, λ _ _ h,
show d _ _, by rw c.eq.2 h; exact d.refl _ ⟩,
left_inv := λ d, subtype.ext.2 $ ext $ λ _ _,
⟨λ h, let ⟨a, b, hx, hy, H⟩ := h in
d.1.trans (d.1.symm $ d.2 a _ $ c.eq.1 hx) $ d.1.trans H $ d.2 b _ $ c.eq.1 hy,
λ h, ⟨_, _, rfl, rfl, h⟩⟩,
right_inv := λ d, let Hm : mul_ker (coe : M → c.quotient) (λ x y, rfl) ≤
comap (coe : M → c.quotient) (λ x y, rfl) d :=
λ x y h, show d _ _, by rw mul_ker_mk_eq at h; exact c.eq.2 h ▸ d.refl _ in
ext $ λ x y, ⟨λ h, let ⟨a, b, hx, hy, H⟩ := h in hx ▸ hy ▸ H,
con.induction_on₂ x y $ λ w z h, ⟨w, z, rfl, rfl, h⟩⟩,
ord := λ s t, ⟨λ h _ _ hs, let ⟨a, b, hx, hy, Hs⟩ := hs in ⟨a, b, hx, hy, h _ _ Hs⟩,
λ h _ _ hs, let ⟨a, b, hx, hy, ht⟩ := h _ _ ⟨_, _, rfl, rfl, hs⟩ in
t.1.trans (t.1.symm $ t.2 a _ $ eq_rel.1 hx) $ t.1.trans ht $ t.2 b _ $ eq_rel.1 hy⟩ }
end
end
-- Monoids
variables {M} [monoid M] [monoid N] [monoid P] (c : con M)
/-- The quotient of a monoid by a congruence relation is a monoid. -/
@[to_additive add_monoid "The quotient of an `add_monoid` by an additive congruence relation is an `add_monoid`."]
instance monoid : monoid c.quotient :=
{ one := ((1 : M) : c.quotient),
mul := (*),
mul_assoc := λ x y z, quotient.induction_on₃' x y z
$ λ _ _ _, congr_arg coe $ mul_assoc _ _ _,
mul_one := λ x, quotient.induction_on' x $ λ _, congr_arg coe $ mul_one _,
one_mul := λ x, quotient.induction_on' x $ λ _, congr_arg coe $ one_mul _ }
/-- The quotient of a `comm_monoid` by a congruence relation is a `comm_monoid`. -/
@[to_additive add_comm_monoid "The quotient of an `add_comm_monoid` by an additive congruence relation is an `add_comm_monoid`."]
instance comm_monoid {α : Type*} [comm_monoid α] (c : con α) :
comm_monoid c.quotient :=
{ mul_comm := λ x y, con.induction_on₂ x y $ λ w z, by rw [←coe_mul, ←coe_mul, mul_comm],
..c.monoid}
variables {c}
/-- The 1 of the quotient of a monoid by a congruence relation is the equivalence class of the
monoid's 1. -/
@[simp, to_additive "The 0 of the quotient of an `add_monoid` by an additive congruence relation is the equivalence class of the `add_monoid`'s 0."]
lemma coe_one : ((1 : M) : c.quotient) = 1 := rfl
variables (M c)
/-- The submonoid of `M × M` defined by a congruence relation on a monoid `M`. -/
@[to_additive add_submonoid "The `add_submonoid` of `M × M` defined by an additive congruence relation on an `add_monoid` `M`."]
protected def submonoid : submonoid (M × M) :=
{ carrier := { x | c x.1 x.2 },
one_mem' := c.iseqv.1 1,
mul_mem' := λ _ _, c.mul }
variables {M c}
/-- The congruence relation on a monoid `M` from a submonoid of `M × M` for which membership
is an equivalence relation. -/
@[to_additive of_add_submonoid "The additive congruence relation on an `add_monoid` `M` from an `add_submonoid` of `M × M` for which membership is an equivalence relation."]
def of_submonoid (N : submonoid (M × M)) (H : equivalence (λ x y, (x, y) ∈ N)) : con M :=
{ r := λ x y, (x, y) ∈ N,
iseqv := H,
mul' := λ _ _ _ _, N.mul_mem }
/-- Coercion from a congruence relation `c` on a monoid `M` to the submonoid of `M × M` whose
elements are `(x, y)` such that `x` is related to `y` by `c`. -/
@[to_additive to_add_submonoid "Coercion from a congruence relation `c` on an `add_monoid` `M` to the `add_submonoid` of `M × M` whose elements are `(x, y)` such that `x` is related to `y` by `c`."]
instance to_submonoid : has_coe (con M) (submonoid (M × M)) := ⟨λ c, c.submonoid M⟩
@[to_additive] lemma mem_coe {c : con M} {x y} :
(x, y) ∈ (↑c : submonoid (M × M)) ↔ (x, y) ∈ c := iff.rfl
@[to_additive to_add_submonoid_inj]
theorem to_submonoid_inj (c d : con M) (H : (c : submonoid (M × M)) = d) : c = d :=
ext $ λ x y, show (x, y) ∈ (c : submonoid (M × M)) ↔ (x, y) ∈ ↑d, by rw H
@[to_additive]
lemma le_iff {c d : con M} : c ≤ d ↔ (c : submonoid (M × M)) ≤ d :=
⟨λ h x, h x.1 x.2, λ h x y hc, h $ show (x, y) ∈ c, from hc⟩
/-- The kernel of a monoid homomorphism as a congruence relation. -/
@[to_additive "The kernel of an `add_monoid` homomorphism as an additive congruence relation."]
def ker (f : M →* P) : con M := mul_ker f f.3
/-- The definition of the congruence relation defined by a monoid homomorphism's kernel. -/
@[to_additive "The definition of the additive congruence relation defined by an `add_monoid` homomorphism's kernel."]
lemma ker_rel (f : M →* P) {x y} : ker f x y ↔ f x = f y := iff.rfl
/-- There exists an element of the quotient of a monoid by a congruence relation (namely 1). -/
@[to_additive "There exists an element of the quotient of an `add_monoid` by a congruence relation (namely 0)."]
instance quotient.inhabited : inhabited c.quotient := ⟨((1 : M) : c.quotient)⟩
variables (c)
/-- The natural homomorphism from a monoid to its quotient by a congruence relation. -/
@[to_additive "The natural homomorphism from an `add_monoid` to its quotient by an additive congruence relation."]
def mk' : M →* c.quotient := ⟨coe, rfl, λ _ _, rfl⟩
variables (x y : M)
/-- The kernel of the natural homomorphism from a monoid to its quotient by a congruence
relation `c` equals `c`. -/
@[simp, to_additive "The kernel of the natural homomorphism from an `add_monoid` to its quotient by an additive congruence relation `c` equals `c`."]
lemma mk'_ker : ker c.mk' = c := ext $ λ _ _, c.eq
variables {c}
/-- The natural homomorphism from a monoid to its quotient by a congruence relation is
surjective. -/
@[to_additive "The natural homomorphism from an `add_monoid` to its quotient by a congruence relation is surjective."]
lemma mk'_surjective : surjective c.mk' :=
λ x, by rcases x; exact ⟨x, rfl⟩
@[simp, to_additive] lemma comp_mk'_apply (g : c.quotient →* P) {x} :
g.comp c.mk' x = g x := rfl
/-- The elements related to `x ∈ M`, `M` a monoid, by the kernel of a monoid homomorphism are
those in the preimage of `f(x)` under `f`. -/
@[to_additive "The elements related to `x ∈ M`, `M` an `add_monoid`, by the kernel of an `add_monoid` homomorphism are those in the preimage of `f(x)` under `f`. "]
lemma ker_apply_eq_preimage {f : M →* P} (x) : (ker f) x = f ⁻¹' {f x} :=
set.ext $ λ x,
⟨λ h, set.mem_preimage.2 $ set.mem_singleton_iff.2 h.symm,
λ h, (set.mem_singleton_iff.1 $ set.mem_preimage.1 h).symm⟩
/-- Given a monoid homomorphism `f : N → M` and a congruence relation `c` on `M`, the congruence
relation induced on `N` by `f` equals the kernel of `c`'s quotient homomorphism composed with
`f`. -/
@[to_additive "Given an `add_monoid` homomorphism `f : N → M` and an additive congruence relation `c` on `M`, the additive congruence relation induced on `N` by `f` equals the kernel of `c`'s quotient homomorphism composed with `f`."]
lemma comap_eq {f : N →* M} : comap f f.map_mul c = ker (c.mk'.comp f) :=
ext $ λ x y, show c _ _ ↔ c.mk' _ = c.mk' _, by rw ←c.eq; refl
variables (c) (f : M →* P)
/-- The homomorphism on the quotient of a monoid by a congruence relation `c` induced by a
homomorphism constant on `c`'s equivalence classes. -/
@[to_additive "The homomorphism on the quotient of an `add_monoid` by an additive congruence relation `c` induced by a homomorphism constant on `c`'s equivalence classes."]
def lift (H : c ≤ ker f) : c.quotient →* P :=
{ to_fun := λ x, con.lift_on x f $ λ _ _, H _ _,
map_one' := by rw ←f.map_one; refl,
map_mul' := λ x y, con.induction_on₂ x y $ λ m n, f.map_mul m n ▸ rfl }
variables {c f}
/-- The diagram describing the universal property for quotients of monoids commutes. -/
@[simp, to_additive "The diagram describing the universal property for quotients of `add_monoid`s commutes."]
lemma lift_mk' (H : c ≤ ker f) (x) :
c.lift f H (c.mk' x) = f x := rfl
/-- The diagram describing the universal property for quotients of monoids commutes. -/
@[simp, to_additive "The diagram describing the universal property for quotients of `add_monoid`s commutes."]
lemma lift_coe (H : c ≤ ker f) (x : M) :
c.lift f H x = f x := rfl
/-- The diagram describing the universal property for quotients of monoids commutes. -/
@[simp, to_additive "The diagram describing the universal property for quotients of `add_monoid`s commutes."]
theorem lift_comp_mk' (H : c ≤ ker f) :
(c.lift f H).comp c.mk' = f := by ext; refl
/-- Given a homomorphism `f` from the quotient of a monoid by a congruence relation, `f` equals the
homomorphism on the quotient induced by `f` composed with the natural map from the monoid to
the quotient. -/
@[simp, to_additive "Given a homomorphism `f` from the quotient of an `add_monoid` by an additive congruence relation, `f` equals the homomorphism on the quotient induced by `f` composed with the natural map from the `add_monoid` to the quotient."]
lemma lift_apply_mk' (f : c.quotient →* P) :
c.lift (f.comp c.mk') (λ x y h, show f ↑x = f ↑y, by rw c.eq.2 h) = f :=
by ext; rcases x; refl
/-- Homomorphisms on the quotient of a monoid by a congruence relation are equal if they
are equal on elements that are coercions from the monoid. -/
@[to_additive "Homomorphisms on the quotient of an `add_monoid` by an additive congruence relation are equal if they are equal on elements that are coercions from the `add_monoid`."]
lemma lift_funext (f g : c.quotient →* P) (h : ∀ a : M, f a = g a) : f = g :=
begin
rw [←lift_apply_mk' f, ←lift_apply_mk' g],
congr' 1,
exact monoid_hom.ext_iff.2 h,
end
/-- The uniqueness part of the universal property for quotients of monoids. -/
@[to_additive "The uniqueness part of the universal property for quotients of `add_monoid`s."]
theorem lift_unique (H : c ≤ ker f) (g : c.quotient →* P)
(Hg : g.comp c.mk' = f) : g = c.lift f H :=
lift_funext g (c.lift f H) $ λ x, by rw [lift_coe H, ←comp_mk'_apply, Hg]
/-- Given a congruence relation `c` on a monoid and a homomorphism `f` constant on `c`'s
equivalence classes, `f` has the same image as the homomorphism that `f` induces on the
quotient. -/
@[to_additive "Given an additive congruence relation `c` on an `add_monoid` and a homomorphism `f` constant on `c`'s equivalence classes, `f` has the same image as the homomorphism that `f` induces on the quotient."]
theorem lift_range (H : c ≤ ker f) : (c.lift f H).mrange = f.mrange :=
submonoid.ext $ λ x,
⟨λ ⟨y, hy⟩, by revert hy; rcases y; exact
λ hy, ⟨y, hy.1, by rw [hy.2.symm, ←lift_coe H]; refl⟩,
λ ⟨y, hy⟩, ⟨↑y, hy.1, by rw ←hy.2; refl⟩⟩
/-- Surjective monoid homomorphisms constant on a congruence relation `c`'s equivalence classes
induce a surjective homomorphism on `c`'s quotient. -/
@[to_additive "Surjective `add_monoid` homomorphisms constant on an additive congruence relation `c`'s equivalence classes induce a surjective homomorphism on `c`'s quotient."]
lemma lift_surjective_of_surjective (h : c ≤ ker f) (hf : surjective f) :
surjective (c.lift f h) :=
λ y, exists.elim (hf y) $ λ w hw, ⟨w, (lift_mk' h w).symm ▸ hw⟩
variables (c f)
/-- Given a monoid homomorphism `f` from `M` to `P`, the kernel of `f` is the unique congruence
relation on `M` whose induced map from the quotient of `M` to `P` is injective. -/
@[to_additive "Given an `add_monoid` homomorphism `f` from `M` to `P`, the kernel of `f` is the unique additive congruence relation on `M` whose induced map from the quotient of `M` to `P` is injective."]
lemma ker_eq_lift_of_injective (H : c ≤ ker f) (h : injective (c.lift f H)) :
ker f = c :=
to_setoid_inj $ ker_eq_lift_of_injective f H h
variables {c}
/-- The homomorphism induced on the quotient of a monoid by the kernel of a monoid homomorphism. -/
@[to_additive "The homomorphism induced on the quotient of an `add_monoid` by the kernel of an `add_monoid` homomorphism."]
def ker_lift : (ker f).quotient →* P :=
(ker f).lift f $ λ _ _, id
variables {f}
/-- The diagram described by the universal property for quotients of monoids, when the congruence
relation is the kernel of the homomorphism, commutes. -/
@[simp, to_additive "The diagram described by the universal property for quotients of `add_monoid`s, when the additive congruence relation is the kernel of the homomorphism, commutes."]
lemma ker_lift_mk (x : M) : ker_lift f x = f x := rfl
/-- Given a monoid homomorphism `f`, the induced homomorphism on the quotient by `f`'s kernel has
the same image as `f`. -/
@[simp, to_additive "Given an `add_monoid` homomorphism `f`, the induced homomorphism on the quotient by `f`'s kernel has the same image as `f`."]
lemma ker_lift_range_eq : (ker_lift f).mrange = f.mrange :=
lift_range $ λ _ _, id
/-- A monoid homomorphism `f` induces an injective homomorphism on the quotient by `f`'s kernel. -/
@[to_additive "An `add_monoid` homomorphism `f` induces an injective homomorphism on the quotient by `f`'s kernel."]
lemma injective_ker_lift (f : M →* P) : injective (ker_lift f) :=
λ x y, quotient.induction_on₂' x y $ λ _ _, (ker f).eq.2
/-- Given congruence relations `c, d` on a monoid such that `d` contains `c`, `d`'s quotient
map induces a homomorphism from the quotient by `c` to the quotient by `d`. -/
@[to_additive "Given additive congruence relations `c, d` on an `add_monoid` such that `d` contains `c`, `d`'s quotient map induces a homomorphism from the quotient by `c` to the quotient by `d`."]
def map (c d : con M) (h : c ≤ d) : c.quotient →* d.quotient :=
c.lift d.mk' $ λ x y hc, show (ker d.mk') x y, from
(mk'_ker d).symm ▸ h x y hc
/-- Given congruence relations `c, d` on a monoid such that `d` contains `c`, the definition of
the homomorphism from the quotient by `c` to the quotient by `d` induced by `d`'s quotient
map. -/
@[to_additive "Given additive congruence relations `c, d` on an `add_monoid` such that `d` contains `c`, the definition of the homomorphism from the quotient by `c` to the quotient by `d` induced by `d`'s quotient map."]
lemma map_apply {c d : con M} (h : c ≤ d) (x) :
c.map d h x = c.lift d.mk' (λ x y hc, d.eq.2 $ h x y hc) x := rfl
variables (c)
/-- The first isomorphism theorem for monoids. -/
@[to_additive "The first isomorphism theorem for `add_monoid`s."]
noncomputable def quotient_ker_equiv_range (f : M →* P) : (ker f).quotient ≃* f.mrange :=
{ map_mul' := monoid_hom.map_mul _,
..@equiv.of_bijective _ _
((@mul_equiv.to_monoid_hom (ker_lift f).mrange _ _ _
$ mul_equiv.submonoid_congr ker_lift_range_eq).comp (ker_lift f).range_restrict) $
bijective_comp (equiv.bijective _)
⟨λ x y h, injective_ker_lift f $ by rcases x; rcases y; injections,
λ ⟨w, z, hzm, hz⟩, ⟨z, by rcases hz; rcases _x; refl⟩⟩ }
/-- The first isomorphism theorem for monoids in the case of a surjective homomorphism. -/
@[to_additive "The first isomorphism theorem for `add_monoid`s in the case of a surjective homomorphism."]
noncomputable def quotient_ker_equiv_of_surjective (f : M →* P) (hf : surjective f) :
(ker f).quotient ≃* P :=
{ map_mul' := monoid_hom.map_mul _,
..@equiv.of_bijective _ _ (ker_lift f)
⟨injective_ker_lift f, lift_surjective_of_surjective (le_refl _) hf⟩ }
/-- The second isomorphism theorem for monoids. -/
@[to_additive "The second isomorphism theorem for `add_monoid`s."]
noncomputable def comap_quotient_equiv (f : N →* M) :
(comap f f.map_mul c).quotient ≃* (c.mk'.comp f).mrange :=
(con.congr comap_eq).trans $ quotient_ker_equiv_range $ c.mk'.comp f
/-- The third isomorphism theorem for monoids. -/
@[to_additive "The third isomorphism theorem for `add_monoid`s."]
def quotient_quotient_equiv_quotient (c d : con M) (h : c ≤ d) :
(ker (c.map d h)).quotient ≃* d.quotient :=
{ map_mul' := λ x y, con.induction_on₂ x y $ λ w z, con.induction_on₂ w z $ λ a b,
show _ = d.mk' a * d.mk' b, by rw ←d.mk'.map_mul; refl,
..quotient_quotient_equiv_quotient _ _ h }
end con
|
9b9db26ed27478e0cffe4669b6d8e165d608924e | 74addaa0e41490cbaf2abd313a764c96df57b05d | /Mathlib/category_theory/sums/basic.lean | f17949c7f65c822b9ba6af4667caabbc08eaddb5 | [] | 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 | 5,425 | lean | /-
Copyright (c) 2019 Scott Morrison. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Scott Morrison
-/
import Mathlib.PrePort
import Mathlib.Lean3Lib.init.default
import Mathlib.category_theory.eq_to_hom
import Mathlib.PostPort
universes u₁ v₁
namespace Mathlib
/-#
Disjoint unions of categories, functors, and natural transformations.
-/
namespace category_theory
/--
`sum C D` gives the direct sum of two categories.
-/
protected instance sum (C : Type u₁) [category C] (D : Type u₁) [category D] : category (C ⊕ D) :=
category.mk
@[simp] theorem sum_comp_inl (C : Type u₁) [category C] (D : Type u₁) [category D] {P : C} {Q : C} {R : C} (f : sum.inl P ⟶ sum.inl Q) (g : sum.inl Q ⟶ sum.inl R) : f ≫ g = f ≫ g :=
rfl
@[simp] theorem sum_comp_inr (C : Type u₁) [category C] (D : Type u₁) [category D] {P : D} {Q : D} {R : D} (f : sum.inr P ⟶ sum.inr Q) (g : sum.inr Q ⟶ sum.inr R) : f ≫ g = f ≫ g :=
rfl
namespace sum
/-- `inl_` is the functor `X ↦ inl X`. -/
-- Unfortunate naming here, suggestions welcome.
def inl_ (C : Type u₁) [category C] (D : Type u₁) [category D] : C ⥤ C ⊕ D :=
functor.mk (fun (X : C) => sum.inl X) fun (X Y : C) (f : X ⟶ Y) => f
/-- `inr_` is the functor `X ↦ inr X`. -/
def inr_ (C : Type u₁) [category C] (D : Type u₁) [category D] : D ⥤ C ⊕ D :=
functor.mk (fun (X : D) => sum.inr X) fun (X Y : D) (f : X ⟶ Y) => f
/-- The functor exchanging two direct summand categories. -/
def swap (C : Type u₁) [category C] (D : Type u₁) [category D] : C ⊕ D ⥤ D ⊕ C :=
functor.mk (fun (X : C ⊕ D) => sorry) fun (X Y : C ⊕ D) (f : X ⟶ Y) => sorry
@[simp] theorem swap_obj_inl (C : Type u₁) [category C] (D : Type u₁) [category D] (X : C) : functor.obj (swap C D) (sum.inl X) = sum.inr X :=
rfl
@[simp] theorem swap_obj_inr (C : Type u₁) [category C] (D : Type u₁) [category D] (X : D) : functor.obj (swap C D) (sum.inr X) = sum.inl X :=
rfl
@[simp] theorem swap_map_inl (C : Type u₁) [category C] (D : Type u₁) [category D] {X : C} {Y : C} {f : sum.inl X ⟶ sum.inl Y} : functor.map (swap C D) f = f :=
rfl
@[simp] theorem swap_map_inr (C : Type u₁) [category C] (D : Type u₁) [category D] {X : D} {Y : D} {f : sum.inr X ⟶ sum.inr Y} : functor.map (swap C D) f = f :=
rfl
namespace swap
/-- `swap` gives an equivalence between `C ⊕ D` and `D ⊕ C`. -/
def equivalence (C : Type u₁) [category C] (D : Type u₁) [category D] : C ⊕ D ≌ D ⊕ C :=
equivalence.mk (swap C D) (swap D C) (nat_iso.of_components (fun (X : C ⊕ D) => eq_to_iso sorry) sorry)
(nat_iso.of_components (fun (X : D ⊕ C) => eq_to_iso sorry) sorry)
protected instance is_equivalence (C : Type u₁) [category C] (D : Type u₁) [category D] : is_equivalence (swap C D) :=
is_equivalence.of_equivalence (equivalence C D)
/-- The double swap on `C ⊕ D` is naturally isomorphic to the identity functor. -/
def symmetry (C : Type u₁) [category C] (D : Type u₁) [category D] : swap C D ⋙ swap D C ≅ 𝟭 :=
iso.symm (equivalence.unit_iso (equivalence C D))
end swap
end sum
namespace functor
/-- The sum of two functors. -/
def sum {A : Type u₁} [category A] {B : Type u₁} [category B] {C : Type u₁} [category C] {D : Type u₁} [category D] (F : A ⥤ B) (G : C ⥤ D) : A ⊕ C ⥤ B ⊕ D :=
mk (fun (X : A ⊕ C) => sorry) fun (X Y : A ⊕ C) (f : X ⟶ Y) => sorry
@[simp] theorem sum_obj_inl {A : Type u₁} [category A] {B : Type u₁} [category B] {C : Type u₁} [category C] {D : Type u₁} [category D] (F : A ⥤ B) (G : C ⥤ D) (a : A) : obj (sum F G) (sum.inl a) = sum.inl (obj F a) :=
rfl
@[simp] theorem sum_obj_inr {A : Type u₁} [category A] {B : Type u₁} [category B] {C : Type u₁} [category C] {D : Type u₁} [category D] (F : A ⥤ B) (G : C ⥤ D) (c : C) : obj (sum F G) (sum.inr c) = sum.inr (obj G c) :=
rfl
@[simp] theorem sum_map_inl {A : Type u₁} [category A] {B : Type u₁} [category B] {C : Type u₁} [category C] {D : Type u₁} [category D] (F : A ⥤ B) (G : C ⥤ D) {a : A} {a' : A} (f : sum.inl a ⟶ sum.inl a') : map (sum F G) f = map F f :=
rfl
@[simp] theorem sum_map_inr {A : Type u₁} [category A] {B : Type u₁} [category B] {C : Type u₁} [category C] {D : Type u₁} [category D] (F : A ⥤ B) (G : C ⥤ D) {c : C} {c' : C} (f : sum.inr c ⟶ sum.inr c') : map (sum F G) f = map G f :=
rfl
end functor
namespace nat_trans
/-- The sum of two natural transformations. -/
def sum {A : Type u₁} [category A] {B : Type u₁} [category B] {C : Type u₁} [category C] {D : Type u₁} [category D] {F : A ⥤ B} {G : A ⥤ B} {H : C ⥤ D} {I : C ⥤ D} (α : F ⟶ G) (β : H ⟶ I) : functor.sum F H ⟶ functor.sum G I :=
mk fun (X : A ⊕ C) => sorry
@[simp] theorem sum_app_inl {A : Type u₁} [category A] {B : Type u₁} [category B] {C : Type u₁} [category C] {D : Type u₁} [category D] {F : A ⥤ B} {G : A ⥤ B} {H : C ⥤ D} {I : C ⥤ D} (α : F ⟶ G) (β : H ⟶ I) (a : A) : app (sum α β) (sum.inl a) = app α a :=
rfl
@[simp] theorem sum_app_inr {A : Type u₁} [category A] {B : Type u₁} [category B] {C : Type u₁} [category C] {D : Type u₁} [category D] {F : A ⥤ B} {G : A ⥤ B} {H : C ⥤ D} {I : C ⥤ D} (α : F ⟶ G) (β : H ⟶ I) (c : C) : app (sum α β) (sum.inr c) = app β c :=
rfl
|
212e4053677a87d3475861d99c6cc3b1dc6107d3 | b00eb947a9c4141624aa8919e94ce6dcd249ed70 | /stage0/src/Init/Data/UInt.lean | bcbbd46633bbfd6f12626d6e3cc2899eecb5fbcc | [
"Apache-2.0"
] | permissive | gebner/lean4-old | a4129a041af2d4d12afb3a8d4deedabde727719b | ee51cdfaf63ee313c914d83264f91f414a0e3b6e | refs/heads/master | 1,683,628,606,745 | 1,622,651,300,000 | 1,622,654,405,000 | 142,608,821 | 1 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 14,736 | lean | /-
Copyright (c) 2018 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
prelude
import Init.Data.Fin.Basic
import Init.System.Platform
open Nat
@[extern "lean_uint8_of_nat"]
def UInt8.ofNat (n : @& Nat) : UInt8 := ⟨Fin.ofNat n⟩
abbrev Nat.toUInt8 := UInt8.ofNat
@[extern "lean_uint8_to_nat"]
def UInt8.toNat (n : UInt8) : Nat := n.val.val
@[extern c inline "#1 + #2"]
def UInt8.add (a b : UInt8) : UInt8 := ⟨a.val + b.val⟩
@[extern c inline "#1 - #2"]
def UInt8.sub (a b : UInt8) : UInt8 := ⟨a.val - b.val⟩
@[extern c inline "#1 * #2"]
def UInt8.mul (a b : UInt8) : UInt8 := ⟨a.val * b.val⟩
@[extern c inline "#2 == 0 ? 0 : #1 / #2"]
def UInt8.div (a b : UInt8) : UInt8 := ⟨a.val / b.val⟩
@[extern c inline "#2 == 0 ? #1 : #1 % #2"]
def UInt8.mod (a b : UInt8) : UInt8 := ⟨a.val % b.val⟩
@[extern "lean_uint8_modn"]
def UInt8.modn (a : UInt8) (n : @& Nat) : UInt8 := ⟨a.val % n⟩
@[extern c inline "#1 & #2"]
def UInt8.land (a b : UInt8) : UInt8 := ⟨Fin.land a.val b.val⟩
@[extern c inline "#1 | #2"]
def UInt8.lor (a b : UInt8) : UInt8 := ⟨Fin.lor a.val b.val⟩
@[extern c inline "#1 ^ #2"]
def UInt8.xor (a b : UInt8) : UInt8 := ⟨Fin.xor a.val b.val⟩
@[extern c inline "#1 << #2 % 8"]
def UInt8.shiftLeft (a b : UInt8) : UInt8 := ⟨a.val <<< (modn b 8).val⟩
@[extern c inline "#1 >> #2 % 8"]
def UInt8.shiftRight (a b : UInt8) : UInt8 := ⟨a.val >>> (modn b 8).val⟩
def UInt8.lt (a b : UInt8) : Prop := a.val < b.val
def UInt8.le (a b : UInt8) : Prop := a.val ≤ b.val
instance : OfNat UInt8 n := ⟨UInt8.ofNat n⟩
instance : Add UInt8 := ⟨UInt8.add⟩
instance : Sub UInt8 := ⟨UInt8.sub⟩
instance : Mul UInt8 := ⟨UInt8.mul⟩
instance : Mod UInt8 := ⟨UInt8.mod⟩
instance : HMod UInt8 Nat UInt8 := ⟨UInt8.modn⟩
instance : Div UInt8 := ⟨UInt8.div⟩
instance : LT UInt8 := ⟨UInt8.lt⟩
instance : LE UInt8 := ⟨UInt8.le⟩
@[extern c inline "~ #1"]
def UInt8.complement (a:UInt8) : UInt8 := 0-(a+1)
instance : Complement UInt8 := ⟨UInt8.complement⟩
instance : AndOp UInt8 := ⟨UInt8.land⟩
instance : OrOp UInt8 := ⟨UInt8.lor⟩
instance : Xor UInt8 := ⟨UInt8.xor⟩
instance : ShiftLeft UInt8 := ⟨UInt8.shiftLeft⟩
instance : ShiftRight UInt8 := ⟨UInt8.shiftRight⟩
set_option bootstrap.genMatcherCode false in
@[extern c inline "#1 < #2"]
def UInt8.decLt (a b : UInt8) : Decidable (a < b) :=
match a, b with
| ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n < m))
set_option bootstrap.genMatcherCode false in
@[extern c inline "#1 <= #2"]
def UInt8.decLe (a b : UInt8) : Decidable (a ≤ b) :=
match a, b with
| ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n <= m))
instance (a b : UInt8) : Decidable (a < b) := UInt8.decLt a b
instance (a b : UInt8) : Decidable (a ≤ b) := UInt8.decLe a b
@[extern "lean_uint16_of_nat"]
def UInt16.ofNat (n : @& Nat) : UInt16 := ⟨Fin.ofNat n⟩
abbrev Nat.toUInt16 := UInt16.ofNat
@[extern "lean_uint16_to_nat"]
def UInt16.toNat (n : UInt16) : Nat := n.val.val
@[extern c inline "#1 + #2"]
def UInt16.add (a b : UInt16) : UInt16 := ⟨a.val + b.val⟩
@[extern c inline "#1 - #2"]
def UInt16.sub (a b : UInt16) : UInt16 := ⟨a.val - b.val⟩
@[extern c inline "#1 * #2"]
def UInt16.mul (a b : UInt16) : UInt16 := ⟨a.val * b.val⟩
@[extern c inline "#2 == 0 ? 0 : #1 / #2"]
def UInt16.div (a b : UInt16) : UInt16 := ⟨a.val / b.val⟩
@[extern c inline "#2 == 0 ? #1 : #1 % #2"]
def UInt16.mod (a b : UInt16) : UInt16 := ⟨a.val % b.val⟩
@[extern "lean_uint16_modn"]
def UInt16.modn (a : UInt16) (n : @& Nat) : UInt16 := ⟨a.val % n⟩
@[extern c inline "#1 & #2"]
def UInt16.land (a b : UInt16) : UInt16 := ⟨Fin.land a.val b.val⟩
@[extern c inline "#1 | #2"]
def UInt16.lor (a b : UInt16) : UInt16 := ⟨Fin.lor a.val b.val⟩
@[extern c inline "#1 ^ #2"]
def UInt16.xor (a b : UInt16) : UInt16 := ⟨Fin.xor a.val b.val⟩
@[extern c inline "#1 << #2 % 16"]
def UInt16.shiftLeft (a b : UInt16) : UInt16 := ⟨a.val <<< (modn b 16).val⟩
@[extern c inline "#1 >> #2 % 16"]
def UInt16.shiftRight (a b : UInt16) : UInt16 := ⟨a.val >>> (modn b 16).val⟩
def UInt16.lt (a b : UInt16) : Prop := a.val < b.val
def UInt16.le (a b : UInt16) : Prop := a.val ≤ b.val
instance : OfNat UInt16 n := ⟨UInt16.ofNat n⟩
instance : Add UInt16 := ⟨UInt16.add⟩
instance : Sub UInt16 := ⟨UInt16.sub⟩
instance : Mul UInt16 := ⟨UInt16.mul⟩
instance : Mod UInt16 := ⟨UInt16.mod⟩
instance : HMod UInt16 Nat UInt16 := ⟨UInt16.modn⟩
instance : Div UInt16 := ⟨UInt16.div⟩
instance : LT UInt16 := ⟨UInt16.lt⟩
instance : LE UInt16 := ⟨UInt16.le⟩
@[extern c inline "~ #1"]
def UInt16.complement (a:UInt16) : UInt16 := 0-(a+1)
instance : Complement UInt16 := ⟨UInt16.complement⟩
instance : AndOp UInt16 := ⟨UInt16.land⟩
instance : OrOp UInt16 := ⟨UInt16.lor⟩
instance : Xor UInt16 := ⟨UInt16.xor⟩
instance : ShiftLeft UInt16 := ⟨UInt16.shiftLeft⟩
instance : ShiftRight UInt16 := ⟨UInt16.shiftRight⟩
set_option bootstrap.genMatcherCode false in
@[extern c inline "#1 < #2"]
def UInt16.decLt (a b : UInt16) : Decidable (a < b) :=
match a, b with
| ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n < m))
set_option bootstrap.genMatcherCode false in
@[extern c inline "#1 <= #2"]
def UInt16.decLe (a b : UInt16) : Decidable (a ≤ b) :=
match a, b with
| ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n <= m))
instance (a b : UInt16) : Decidable (a < b) := UInt16.decLt a b
instance (a b : UInt16) : Decidable (a ≤ b) := UInt16.decLe a b
@[extern "lean_uint32_of_nat"]
def UInt32.ofNat (n : @& Nat) : UInt32 := ⟨Fin.ofNat n⟩
@[extern "lean_uint32_of_nat"]
def UInt32.ofNat' (n : Nat) (h : n < UInt32.size) : UInt32 := ⟨⟨n, h⟩⟩
abbrev Nat.toUInt32 := UInt32.ofNat
@[extern c inline "#1 + #2"]
def UInt32.add (a b : UInt32) : UInt32 := ⟨a.val + b.val⟩
@[extern c inline "#1 - #2"]
def UInt32.sub (a b : UInt32) : UInt32 := ⟨a.val - b.val⟩
@[extern c inline "#1 * #2"]
def UInt32.mul (a b : UInt32) : UInt32 := ⟨a.val * b.val⟩
@[extern c inline "#2 == 0 ? 0 : #1 / #2"]
def UInt32.div (a b : UInt32) : UInt32 := ⟨a.val / b.val⟩
@[extern c inline "#2 == 0 ? #1 : #1 % #2"]
def UInt32.mod (a b : UInt32) : UInt32 := ⟨a.val % b.val⟩
@[extern "lean_uint32_modn"]
def UInt32.modn (a : UInt32) (n : @& Nat) : UInt32 := ⟨a.val % n⟩
@[extern c inline "#1 & #2"]
def UInt32.land (a b : UInt32) : UInt32 := ⟨Fin.land a.val b.val⟩
@[extern c inline "#1 | #2"]
def UInt32.lor (a b : UInt32) : UInt32 := ⟨Fin.lor a.val b.val⟩
@[extern c inline "#1 ^ #2"]
def UInt32.xor (a b : UInt32) : UInt32 := ⟨Fin.xor a.val b.val⟩
@[extern c inline "#1 << #2 % 32"]
def UInt32.shiftLeft (a b : UInt32) : UInt32 := ⟨a.val <<< (modn b 32).val⟩
@[extern c inline "#1 >> #2 % 32"]
def UInt32.shiftRight (a b : UInt32) : UInt32 := ⟨a.val >>> (modn b 32).val⟩
@[extern c inline "((uint8_t)#1)"]
def UInt32.toUInt8 (a : UInt32) : UInt8 := a.toNat.toUInt8
@[extern c inline "((uint16_t)#1)"]
def UInt32.toUInt16 (a : UInt32) : UInt16 := a.toNat.toUInt16
@[extern c inline "((uint32_t)#1)"]
def UInt8.toUInt32 (a : UInt8) : UInt32 := a.toNat.toUInt32
instance : OfNat UInt32 n := ⟨UInt32.ofNat n⟩
instance : Add UInt32 := ⟨UInt32.add⟩
instance : Sub UInt32 := ⟨UInt32.sub⟩
instance : Mul UInt32 := ⟨UInt32.mul⟩
instance : Mod UInt32 := ⟨UInt32.mod⟩
instance : HMod UInt32 Nat UInt32 := ⟨UInt32.modn⟩
instance : Div UInt32 := ⟨UInt32.div⟩
@[extern c inline "~ #1"]
def UInt32.complement (a:UInt32) : UInt32 := 0-(a+1)
instance : Complement UInt32 := ⟨UInt32.complement⟩
instance : AndOp UInt32 := ⟨UInt32.land⟩
instance : OrOp UInt32 := ⟨UInt32.lor⟩
instance : Xor UInt32 := ⟨UInt32.xor⟩
instance : ShiftLeft UInt32 := ⟨UInt32.shiftLeft⟩
instance : ShiftRight UInt32 := ⟨UInt32.shiftRight⟩
@[extern "lean_uint64_of_nat"]
def UInt64.ofNat (n : @& Nat) : UInt64 := ⟨Fin.ofNat n⟩
abbrev Nat.toUInt64 := UInt64.ofNat
@[extern "lean_uint64_to_nat"]
def UInt64.toNat (n : UInt64) : Nat := n.val.val
@[extern c inline "#1 + #2"]
def UInt64.add (a b : UInt64) : UInt64 := ⟨a.val + b.val⟩
@[extern c inline "#1 - #2"]
def UInt64.sub (a b : UInt64) : UInt64 := ⟨a.val - b.val⟩
@[extern c inline "#1 * #2"]
def UInt64.mul (a b : UInt64) : UInt64 := ⟨a.val * b.val⟩
@[extern c inline "#2 == 0 ? 0 : #1 / #2"]
def UInt64.div (a b : UInt64) : UInt64 := ⟨a.val / b.val⟩
@[extern c inline "#2 == 0 ? #1 : #1 % #2"]
def UInt64.mod (a b : UInt64) : UInt64 := ⟨a.val % b.val⟩
@[extern "lean_uint64_modn"]
def UInt64.modn (a : UInt64) (n : @& Nat) : UInt64 := ⟨a.val % n⟩
@[extern c inline "#1 & #2"]
def UInt64.land (a b : UInt64) : UInt64 := ⟨Fin.land a.val b.val⟩
@[extern c inline "#1 | #2"]
def UInt64.lor (a b : UInt64) : UInt64 := ⟨Fin.lor a.val b.val⟩
@[extern c inline "#1 ^ #2"]
def UInt64.xor (a b : UInt64) : UInt64 := ⟨Fin.xor a.val b.val⟩
@[extern c inline "#1 << #2 % 64"]
def UInt64.shiftLeft (a b : UInt64) : UInt64 := ⟨a.val <<< (modn b 64).val⟩
@[extern c inline "#1 >> #2 % 64"]
def UInt64.shiftRight (a b : UInt64) : UInt64 := ⟨a.val >>> (modn b 64).val⟩
def UInt64.lt (a b : UInt64) : Prop := a.val < b.val
def UInt64.le (a b : UInt64) : Prop := a.val ≤ b.val
@[extern c inline "((uint8_t)#1)"]
def UInt64.toUInt8 (a : UInt64) : UInt8 := a.toNat.toUInt8
@[extern c inline "((uint16_t)#1)"]
def UInt64.toUInt16 (a : UInt64) : UInt16 := a.toNat.toUInt16
@[extern c inline "((uint32_t)#1)"]
def UInt64.toUInt32 (a : UInt64) : UInt32 := a.toNat.toUInt32
@[extern c inline "((uint64_t)#1)"]
def UInt32.toUInt64 (a : UInt32) : UInt64 := a.toNat.toUInt64
instance : OfNat UInt64 n := ⟨UInt64.ofNat n⟩
instance : Add UInt64 := ⟨UInt64.add⟩
instance : Sub UInt64 := ⟨UInt64.sub⟩
instance : Mul UInt64 := ⟨UInt64.mul⟩
instance : Mod UInt64 := ⟨UInt64.mod⟩
instance : HMod UInt64 Nat UInt64 := ⟨UInt64.modn⟩
instance : Div UInt64 := ⟨UInt64.div⟩
instance : LT UInt64 := ⟨UInt64.lt⟩
instance : LE UInt64 := ⟨UInt64.le⟩
@[extern c inline "~ #1"]
def UInt64.complement (a:UInt64) : UInt64 := 0-(a+1)
instance : Complement UInt64 := ⟨UInt64.complement⟩
instance : AndOp UInt64 := ⟨UInt64.land⟩
instance : OrOp UInt64 := ⟨UInt64.lor⟩
instance : Xor UInt64 := ⟨UInt64.xor⟩
instance : ShiftLeft UInt64 := ⟨UInt64.shiftLeft⟩
instance : ShiftRight UInt64 := ⟨UInt64.shiftRight⟩
@[extern c inline "(uint64_t)#1"]
def Bool.toUInt64 (b : Bool) : UInt64 := if b then 1 else 0
set_option bootstrap.genMatcherCode false in
@[extern c inline "#1 < #2"]
def UInt64.decLt (a b : UInt64) : Decidable (a < b) :=
match a, b with
| ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n < m))
set_option bootstrap.genMatcherCode false in
@[extern c inline "#1 <= #2"]
def UInt64.decLe (a b : UInt64) : Decidable (a ≤ b) :=
match a, b with
| ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n <= m))
instance (a b : UInt64) : Decidable (a < b) := UInt64.decLt a b
instance (a b : UInt64) : Decidable (a ≤ b) := UInt64.decLe a b
theorem usizeSzGt0 : USize.size > 0 :=
Nat.posPowOfPos System.Platform.numBits (Nat.zeroLtSucc _)
@[extern "lean_usize_of_nat"]
def USize.ofNat (n : @& Nat) : USize := ⟨Fin.ofNat' n usizeSzGt0⟩
abbrev Nat.toUSize := USize.ofNat
@[extern "lean_usize_to_nat"]
def USize.toNat (n : USize) : Nat := n.val.val
@[extern c inline "#1 + #2"]
def USize.add (a b : USize) : USize := ⟨a.val + b.val⟩
@[extern c inline "#1 - #2"]
def USize.sub (a b : USize) : USize := ⟨a.val - b.val⟩
@[extern c inline "#1 * #2"]
def USize.mul (a b : USize) : USize := ⟨a.val * b.val⟩
@[extern c inline "#2 == 0 ? 0 : #1 / #2"]
def USize.div (a b : USize) : USize := ⟨a.val / b.val⟩
@[extern c inline "#2 == 0 ? #1 : #1 % #2"]
def USize.mod (a b : USize) : USize := ⟨a.val % b.val⟩
@[extern "lean_usize_modn"]
def USize.modn (a : USize) (n : @& Nat) : USize := ⟨a.val % n⟩
@[extern c inline "#1 & #2"]
def USize.land (a b : USize) : USize := ⟨Fin.land a.val b.val⟩
@[extern c inline "#1 | #2"]
def USize.lor (a b : USize) : USize := ⟨Fin.lor a.val b.val⟩
@[extern c inline "#1 ^ #2"]
def USize.xor (a b : USize) : USize := ⟨Fin.xor a.val b.val⟩
@[extern c inline "#1 << #2 % (sizeof(size_t) * 8)"]
def USize.shiftLeft (a b : USize) : USize := ⟨a.val <<< (modn b System.Platform.numBits).val⟩
@[extern c inline "#1 >> #2 % (sizeof(size_t) * 8)"]
def USize.shiftRight (a b : USize) : USize := ⟨a.val >>> (modn b System.Platform.numBits).val⟩
@[extern c inline "#1"]
def UInt32.toUSize (a : UInt32) : USize := a.toNat.toUSize
@[extern c inline "((size_t)#1)"]
def UInt64.toUSize (a : UInt64) : USize := a.toNat.toUSize
@[extern c inline "(uint32_t)#1"]
def USize.toUInt32 (a : USize) : UInt32 := a.toNat.toUInt32
def USize.lt (a b : USize) : Prop := a.val < b.val
def USize.le (a b : USize) : Prop := a.val ≤ b.val
instance : OfNat USize n := ⟨USize.ofNat n⟩
instance : Add USize := ⟨USize.add⟩
instance : Sub USize := ⟨USize.sub⟩
instance : Mul USize := ⟨USize.mul⟩
instance : Mod USize := ⟨USize.mod⟩
instance : HMod USize Nat USize := ⟨USize.modn⟩
instance : Div USize := ⟨USize.div⟩
instance : LT USize := ⟨USize.lt⟩
instance : LE USize := ⟨USize.le⟩
@[extern c inline "~ #1"]
def USize.complement (a:USize) : USize := 0-(a+1)
instance : Complement USize := ⟨USize.complement⟩
instance : AndOp USize := ⟨USize.land⟩
instance : OrOp USize := ⟨USize.lor⟩
instance : Xor USize := ⟨USize.xor⟩
instance : ShiftLeft USize := ⟨USize.shiftLeft⟩
instance : ShiftRight USize := ⟨USize.shiftRight⟩
set_option bootstrap.genMatcherCode false in
@[extern c inline "#1 < #2"]
def USize.decLt (a b : USize) : Decidable (a < b) :=
match a, b with
| ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n < m))
set_option bootstrap.genMatcherCode false in
@[extern c inline "#1 <= #2"]
def USize.decLe (a b : USize) : Decidable (a ≤ b) :=
match a, b with
| ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n <= m))
instance (a b : USize) : Decidable (a < b) := USize.decLt a b
instance (a b : USize) : Decidable (a ≤ b) := USize.decLe a b
theorem USize.modn_lt {m : Nat} : ∀ (u : USize), m > 0 → USize.toNat (u % m) < m
| ⟨u⟩, h => Fin.modn_lt u h
|
670439c54f3086c0398ca1d032b2b5d5686f35d3 | 9be442d9ec2fcf442516ed6e9e1660aa9071b7bd | /stage0/src/Lean/Server/FileWorker/WidgetRequests.lean | df9de092dcbaf84b26447fb41631ec8896aac3fd | [
"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 | EdAyers/lean4 | 57ac632d6b0789cb91fab2170e8c9e40441221bd | 37ba0df5841bde51dbc2329da81ac23d4f6a4de4 | refs/heads/master | 1,676,463,245,298 | 1,660,619,433,000 | 1,660,619,433,000 | 183,433,437 | 1 | 0 | Apache-2.0 | 1,657,612,672,000 | 1,556,196,574,000 | Lean | UTF-8 | Lean | false | false | 4,838 | lean | /-
Copyright (c) 2021 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Wojciech Nawrocki
-/
import Lean.Widget.Basic
import Lean.Widget.InteractiveCode
import Lean.Widget.InteractiveGoal
import Lean.Widget.InteractiveDiagnostic
import Lean.Server.Rpc.RequestHandling
import Lean.Server.FileWorker.RequestHandling
/-! Registers all widget-related RPC procedures. -/
namespace Lean.Widget
open Server
structure MsgToInteractive where
msg : WithRpcRef MessageData
indent : Nat
deriving Inhabited, RpcEncodable
builtin_initialize
registerBuiltinRpcProcedure
`Lean.Widget.InteractiveDiagnostics.msgToInteractive
MsgToInteractive
(TaggedText MsgEmbed)
fun ⟨⟨m⟩, i⟩ => RequestM.asTask do msgToInteractive m i (hasWidgets := true)
/-- The information that the infoview uses to render a popup
for when the user hovers over an expression.
-/
structure InfoPopup where
type : Option CodeWithInfos
/-- Show the term with the implicit arguments. -/
exprExplicit : Option CodeWithInfos
/-- Docstring. In markdown. -/
doc : Option String
deriving Inhabited, RpcEncodable
/-- Given elaborator info for a particular subexpression. Produce the `InfoPopup`.
The intended usage of this is for the infoview to pass the `InfoWithCtx` which
was stored for a particular `SubexprInfo` tag in a `TaggedText` generated with `ppExprTagged`.
-/
def makePopup : WithRpcRef InfoWithCtx → RequestM (RequestTask InfoPopup)
| ⟨i⟩ => RequestM.asTask do
i.ctx.runMetaM i.info.lctx do
let type? ← match (← i.info.type?) with
| some type => some <$> ppExprTagged type
| none => pure none
let exprExplicit? ← match i.info with
| Elab.Info.ofTermInfo ti =>
let ti ← ppExprTagged ti.expr (explicit := true)
-- remove top-level expression highlight
pure <| some <| match ti with
| .tag _ tt => tt
| tt => tt
| Elab.Info.ofFieldInfo fi => pure <| some <| TaggedText.text fi.fieldName.toString
| _ => pure none
return {
type := type?
exprExplicit := exprExplicit?
doc := ← i.info.docString? : InfoPopup
}
builtin_initialize
registerBuiltinRpcProcedure
`Lean.Widget.InteractiveDiagnostics.infoToInteractive
(WithRpcRef InfoWithCtx)
InfoPopup
makePopup
builtin_initialize
registerBuiltinRpcProcedure
`Lean.Widget.getInteractiveGoals
Lsp.PlainGoalParams
(Option InteractiveGoals)
FileWorker.getInteractiveGoals
builtin_initialize
registerBuiltinRpcProcedure
`Lean.Widget.getInteractiveTermGoal
Lsp.PlainTermGoalParams
(Option InteractiveTermGoal)
FileWorker.getInteractiveTermGoal
structure GetInteractiveDiagnosticsParams where
/-- Return diagnostics for these lines only if present,
otherwise return all diagnostics. -/
lineRange? : Option Lsp.LineRange
deriving Inhabited, FromJson, ToJson
open RequestM in
def getInteractiveDiagnostics (params : GetInteractiveDiagnosticsParams) : RequestM (RequestTask (Array InteractiveDiagnostic)) := do
let doc ← readDoc
let rangeEnd := params.lineRange?.map fun range =>
doc.meta.text.lspPosToUtf8Pos ⟨range.«end», 0⟩
let t ← doc.cmdSnaps.waitAll fun snap => rangeEnd.all (snap.beginPos < ·)
pure <| t.map fun (snaps, _) =>
let diags? := snaps.getLast?.map fun snap =>
snap.interactiveDiags.toArray.filter fun diag =>
params.lineRange?.all fun ⟨s, e⟩ =>
-- does [s,e) intersect [diag.fullRange.start.line,diag.fullRange.end.line)?
s ≤ diag.fullRange.start.line ∧ diag.fullRange.start.line < e ∨
diag.fullRange.start.line ≤ s ∧ s < diag.fullRange.end.line
pure <| diags?.getD #[]
builtin_initialize
registerBuiltinRpcProcedure
`Lean.Widget.getInteractiveDiagnostics
GetInteractiveDiagnosticsParams
(Array InteractiveDiagnostic)
getInteractiveDiagnostics
structure GetGoToLocationParams where
kind : GoToKind
info : WithRpcRef InfoWithCtx
deriving RpcEncodable
builtin_initialize
registerBuiltinRpcProcedure
`Lean.Widget.getGoToLocation
GetGoToLocationParams
(Array Lsp.LocationLink)
fun ⟨kind, ⟨i⟩⟩ => RequestM.asTask do
let rc ← read
let ls ← FileWorker.locationLinksOfInfo kind i.ctx i.info
if !ls.isEmpty then return ls
-- TODO(WN): unify handling of delab'd (infoview) and elab'd (editor) applications
let .ofTermInfo ti := i.info | return #[]
let .app _ _ := ti.expr | return #[]
let some nm := ti.expr.getAppFn.constName? | return #[]
i.ctx.runMetaM ti.lctx <|
locationLinksFromDecl rc.srcSearchPath rc.doc.meta.uri nm none
end Lean.Widget
|
7e0ed2b07f45dc6658dbea481cd26c3b561b5b54 | 35677d2df3f081738fa6b08138e03ee36bc33cad | /src/algebra/opposites.lean | 17032127e2c423e0b44ab9122bd995d4ae5d193f | [
"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 | 5,752 | lean | /-
Copyright (c) 2018 Kenny Lau. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kenny Lau
Opposites.
-/
import data.opposite
namespace opposite
universes u
variables (α : Type u)
instance [has_add α] : has_add (opposite α) :=
{ add := λ x y, op (unop x + unop y) }
instance [add_semigroup α] : add_semigroup (opposite α) :=
{ add_assoc := λ x y z, unop_inj $ add_assoc (unop x) (unop y) (unop z),
.. opposite.has_add α }
instance [add_left_cancel_semigroup α] : add_left_cancel_semigroup (opposite α) :=
{ add_left_cancel := λ x y z H, unop_inj $ add_left_cancel $ op_inj H,
.. opposite.add_semigroup α }
instance [add_right_cancel_semigroup α] : add_right_cancel_semigroup (opposite α) :=
{ add_right_cancel := λ x y z H, unop_inj $ add_right_cancel $ op_inj H,
.. opposite.add_semigroup α }
instance [add_comm_semigroup α] : add_comm_semigroup (opposite α) :=
{ add_comm := λ x y, unop_inj $ add_comm (unop x) (unop y),
.. opposite.add_semigroup α }
instance [has_zero α] : has_zero (opposite α) :=
{ zero := op 0 }
instance [add_monoid α] : add_monoid (opposite α) :=
{ zero_add := λ x, unop_inj $ zero_add $ unop x,
add_zero := λ x, unop_inj $ add_zero $ unop x,
.. opposite.add_semigroup α, .. opposite.has_zero α }
instance [add_comm_monoid α] : add_comm_monoid (opposite α) :=
{ .. opposite.add_monoid α, .. opposite.add_comm_semigroup α }
instance [has_neg α] : has_neg (opposite α) :=
{ neg := λ x, op $ -(unop x) }
instance [add_group α] : add_group (opposite α) :=
{ add_left_neg := λ x, unop_inj $ add_left_neg $ unop x,
.. opposite.add_monoid α, .. opposite.has_neg α }
instance [add_comm_group α] : add_comm_group (opposite α) :=
{ .. opposite.add_group α, .. opposite.add_comm_monoid α }
instance [has_mul α] : has_mul (opposite α) :=
{ mul := λ x y, op (unop y * unop x) }
instance [semigroup α] : semigroup (opposite α) :=
{ mul_assoc := λ x y z, unop_inj $ eq.symm $ mul_assoc (unop z) (unop y) (unop x),
.. opposite.has_mul α }
instance [right_cancel_semigroup α] : left_cancel_semigroup (opposite α) :=
{ mul_left_cancel := λ x y z H, unop_inj $ mul_right_cancel $ op_inj H,
.. opposite.semigroup α }
instance [left_cancel_semigroup α] : right_cancel_semigroup (opposite α) :=
{ mul_right_cancel := λ x y z H, unop_inj $ mul_left_cancel $ op_inj H,
.. opposite.semigroup α }
instance [comm_semigroup α] : comm_semigroup (opposite α) :=
{ mul_comm := λ x y, unop_inj $ mul_comm (unop y) (unop x),
.. opposite.semigroup α }
instance [has_one α] : has_one (opposite α) :=
{ one := op 1 }
instance [monoid α] : monoid (opposite α) :=
{ one_mul := λ x, unop_inj $ mul_one $ unop x,
mul_one := λ x, unop_inj $ one_mul $ unop x,
.. opposite.semigroup α, .. opposite.has_one α }
instance [comm_monoid α] : comm_monoid (opposite α) :=
{ .. opposite.monoid α, .. opposite.comm_semigroup α }
instance [has_inv α] : has_inv (opposite α) :=
{ inv := λ x, op $ (unop x)⁻¹ }
instance [group α] : group (opposite α) :=
{ mul_left_inv := λ x, unop_inj $ mul_inv_self $ unop x,
.. opposite.monoid α, .. opposite.has_inv α }
instance [comm_group α] : comm_group (opposite α) :=
{ .. opposite.group α, .. opposite.comm_monoid α }
instance [distrib α] : distrib (opposite α) :=
{ left_distrib := λ x y z, unop_inj $ add_mul (unop y) (unop z) (unop x),
right_distrib := λ x y z, unop_inj $ mul_add (unop z) (unop x) (unop y),
.. opposite.has_add α, .. opposite.has_mul α }
instance [semiring α] : semiring (opposite α) :=
{ zero_mul := λ x, unop_inj $ mul_zero $ unop x,
mul_zero := λ x, unop_inj $ zero_mul $ unop x,
.. opposite.add_comm_monoid α, .. opposite.monoid α, .. opposite.distrib α }
instance [ring α] : ring (opposite α) :=
{ .. opposite.add_comm_group α, .. opposite.monoid α, .. opposite.semiring α }
instance [comm_ring α] : comm_ring (opposite α) :=
{ .. opposite.ring α, .. opposite.comm_semigroup α }
instance [zero_ne_one_class α] : zero_ne_one_class (opposite α) :=
{ zero_ne_one := λ h, zero_ne_one $ op_inj h,
.. opposite.has_zero α, .. opposite.has_one α }
instance [integral_domain α] : integral_domain (opposite α) :=
{ eq_zero_or_eq_zero_of_mul_eq_zero := λ x y (H : op _ = op (0:α)),
or.cases_on (eq_zero_or_eq_zero_of_mul_eq_zero $ op_inj H)
(λ hy, or.inr $ unop_inj $ hy) (λ hx, or.inl $ unop_inj $ hx),
.. opposite.comm_ring α, .. opposite.zero_ne_one_class α }
instance [field α] : field (opposite α) :=
{ mul_inv_cancel := λ x hx, unop_inj $ inv_mul_cancel $ λ hx', hx $ unop_inj hx',
inv_zero := unop_inj inv_zero,
.. opposite.comm_ring α, .. opposite.zero_ne_one_class α, .. opposite.has_inv α }
@[simp] lemma op_zero [has_zero α] : op (0 : α) = 0 := rfl
@[simp] lemma unop_zero [has_zero α] : unop (0 : αᵒᵖ) = 0 := rfl
@[simp] lemma op_one [has_one α] : op (1 : α) = 1 := rfl
@[simp] lemma unop_one [has_one α] : unop (1 : αᵒᵖ) = 1 := rfl
variable {α}
@[simp] lemma op_add [has_add α] (x y : α) : op (x + y) = op x + op y := rfl
@[simp] lemma unop_add [has_add α] (x y : αᵒᵖ) : unop (x + y) = unop x + unop y := rfl
@[simp] lemma op_neg [has_neg α] (x : α) : op (-x) = -op x := rfl
@[simp] lemma unop_neg [has_neg α] (x : αᵒᵖ) : unop (-x) = -unop x := rfl
@[simp] lemma op_mul [has_mul α] (x y : α) : op (x * y) = op y * op x := rfl
@[simp] lemma unop_mul [has_mul α] (x y : αᵒᵖ) : unop (x * y) = unop y * unop x := rfl
@[simp] lemma op_inv [has_inv α] (x : α) : op (x⁻¹) = (op x)⁻¹ := rfl
@[simp] lemma unop_inv [has_inv α] (x : αᵒᵖ) : unop (x⁻¹) = (unop x)⁻¹ := rfl
end opposite
|
0f7e216b870d3682582eb6bce08ad6c1054ef604 | fa02ed5a3c9c0adee3c26887a16855e7841c668b | /src/category_theory/discrete_category.lean | dc7a2173406831117e9feaa81c07874b72b8b114 | [
"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 | 6,199 | 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, Floris van Doorn
-/
import category_theory.eq_to_hom
/-!
# Discrete categories
We define `discrete α := α` for any type `α`, and use this type alias
to provide a `small_category` instance whose only morphisms are the identities.
There is an annoying technical difficulty that it has turned out to be inconvenient
to allow categories with morphisms living in `Prop`,
so instead of defining `X ⟶ Y` in `discrete α` as `X = Y`,
one might define it as `plift (X = Y)`.
In fact, to allow `discrete α` to be a `small_category`
(i.e. with morphisms in the same universe as the objects),
we actually define the hom type `X ⟶ Y` as `ulift (plift (X = Y))`.
`discrete.functor` promotes a function `f : I → C` (for any category `C`) to a functor
`discrete.functor f : discrete I ⥤ C`.
Similarly, `discrete.nat_trans` and `discrete.nat_iso` promote `I`-indexed families of morphisms,
or `I`-indexed families of isomorphisms to natural transformations or natural isomorphism.
We show equivalences of types are the same as (categorical) equivalences of the corresponding
discrete categories.
-/
namespace category_theory
universes v₁ v₂ u₁ u₂ -- morphism levels before object levels. See note [category_theory universes].
/--
A type synonym for promoting any type to a category,
with the only morphisms being equalities.
-/
def discrete (α : Type u₁) := α
/--
The "discrete" category on a type, whose morphisms are equalities.
Because we do not allow morphisms in `Prop` (only in `Type`),
somewhat annoyingly we have to define `X ⟶ Y` as `ulift (plift (X = Y))`.
See https://stacks.math.columbia.edu/tag/001A
-/
instance discrete_category (α : Type u₁) : small_category (discrete α) :=
{ hom := λ X Y, ulift (plift (X = Y)),
id := λ X, ulift.up (plift.up rfl),
comp := λ X Y Z g f, by { rcases f with ⟨⟨rfl⟩⟩, exact g } }
namespace discrete
variables {α : Type u₁}
instance [inhabited α] : inhabited (discrete α) :=
by { dsimp [discrete], apply_instance }
instance [subsingleton α] : subsingleton (discrete α) :=
by { dsimp [discrete], apply_instance }
/-- Extract the equation from a morphism in a discrete category. -/
lemma eq_of_hom {X Y : discrete α} (i : X ⟶ Y) : X = Y := i.down.down
@[simp] lemma id_def (X : discrete α) : ulift.up (plift.up (eq.refl X)) = 𝟙 X := rfl
variables {C : Type u₂} [category.{v₂} C]
instance {I : Type u₁} {i j : discrete I} (f : i ⟶ j) : is_iso f :=
⟨⟨eq_to_hom (eq_of_hom f).symm, by tidy⟩⟩
/--
Any function `I → C` gives a functor `discrete I ⥤ C`.
-/
def functor {I : Type u₁} (F : I → C) : discrete I ⥤ C :=
{ obj := F,
map := λ X Y f, begin cases f, cases f, cases f, exact 𝟙 (F X) end }
@[simp] lemma functor_obj {I : Type u₁} (F : I → C) (i : I) :
(discrete.functor F).obj i = F i := rfl
lemma functor_map {I : Type u₁} (F : I → C) {i : discrete I} (f : i ⟶ i) :
(discrete.functor F).map f = 𝟙 (F i) :=
by { cases f, cases f, cases f, refl }
/--
For functors out of a discrete category,
a natural transformation is just a collection of maps,
as the naturality squares are trivial.
-/
def nat_trans {I : Type u₁} {F G : discrete I ⥤ C}
(f : Π i : discrete I, F.obj i ⟶ G.obj i) : F ⟶ G :=
{ app := f }
@[simp] lemma nat_trans_app {I : Type u₁} {F G : discrete I ⥤ C}
(f : Π i : discrete I, F.obj i ⟶ G.obj i) (i) : (discrete.nat_trans f).app i = f i :=
rfl
/--
For functors out of a discrete category,
a natural isomorphism is just a collection of isomorphisms,
as the naturality squares are trivial.
-/
def nat_iso {I : Type u₁} {F G : discrete I ⥤ C}
(f : Π i : discrete I, F.obj i ≅ G.obj i) : F ≅ G :=
nat_iso.of_components f (by tidy)
@[simp]
lemma nat_iso_hom_app {I : Type u₁} {F G : discrete I ⥤ C}
(f : Π i : discrete I, F.obj i ≅ G.obj i) (i : I) :
(discrete.nat_iso f).hom.app i = (f i).hom :=
rfl
@[simp]
lemma nat_iso_inv_app {I : Type u₁} {F G : discrete I ⥤ C}
(f : Π i : discrete I, F.obj i ≅ G.obj i) (i : I) :
(discrete.nat_iso f).inv.app i = (f i).inv :=
rfl
@[simp]
lemma nat_iso_app {I : Type u₁} {F G : discrete I ⥤ C}
(f : Π i : discrete I, F.obj i ≅ G.obj i) (i : I) :
(discrete.nat_iso f).app i = f i :=
by tidy
/-- Every functor `F` from a discrete category is naturally isomorphic (actually, equal) to
`discrete.functor (F.obj)`. -/
def nat_iso_functor {I : Type u₁} {F : discrete I ⥤ C} : F ≅ discrete.functor (F.obj) :=
nat_iso $ λ i, iso.refl _
/--
We can promote a type-level `equiv` to
an equivalence between the corresponding `discrete` categories.
-/
@[simps]
def equivalence {I J : Type u₁} (e : I ≃ J) : discrete I ≌ discrete J :=
{ functor := discrete.functor (e : I → J),
inverse := discrete.functor (e.symm : J → I),
unit_iso := discrete.nat_iso (λ i, eq_to_iso (by simp)),
counit_iso := discrete.nat_iso (λ j, eq_to_iso (by simp)), }
/-- We can convert an equivalence of `discrete` categories to a type-level `equiv`. -/
@[simps]
def equiv_of_equivalence {α β : Type u₁} (h : discrete α ≌ discrete β) : α ≃ β :=
{ to_fun := h.functor.obj,
inv_fun := h.inverse.obj,
left_inv := λ a, eq_of_hom (h.unit_iso.app a).2,
right_inv := λ a, eq_of_hom (h.counit_iso.app a).1 }
end discrete
namespace discrete
variables {J : Type v₁}
open opposite
/-- A discrete category is equivalent to its opposite category. -/
protected def opposite (α : Type u₁) : (discrete α)ᵒᵖ ≌ discrete α :=
let F : discrete α ⥤ (discrete α)ᵒᵖ := discrete.functor (λ x, op x) in
begin
refine equivalence.mk (functor.left_op F) F _ (discrete.nat_iso $ λ X, by simp [F]),
refine nat_iso.of_components (λ X, by simp [F]) _,
tidy
end
variables {C : Type u₂} [category.{v₂} C]
@[simp] lemma functor_map_id
(F : discrete J ⥤ C) {j : discrete J} (f : j ⟶ j) : F.map f = 𝟙 (F.obj j) :=
begin
have h : f = 𝟙 j, { cases f, cases f, ext, },
rw h,
simp,
end
end discrete
end category_theory
|
0538c9c7c03c2994beef94cc8cd5d373f2260a40 | 2385ce0e3b60d8dbea33dd439902a2070cca7a24 | /tests/lean/guard_names.lean | 29c8c9b9a01f13e07a328569c7deba40b6040008 | [
"Apache-2.0"
] | permissive | TehMillhouse/lean | 68d6fdd2fb11a6c65bc28dec308d70f04dad38b4 | 6bbf2fbd8912617e5a973575bab8c383c9c268a1 | refs/heads/master | 1,620,830,893,339 | 1,515,592,479,000 | 1,515,592,997,000 | 116,964,828 | 0 | 0 | null | 1,515,592,734,000 | 1,515,592,734,000 | null | UTF-8 | Lean | false | false | 297 | lean | inductive tree (α : Type)
| leaf : tree
| node (left : tree) (val : α) (right : tree) : tree
constant foo {α : Type} : tree α → tree α
example {α : Type} (a b : tree α) : foo a = a :=
begin
with_cases { induction a },
{ sorry },
case : l v r ih_l ih_r { trace_state, sorry },
end
|
aa76bcbf46b247f2af658b8dbf922aedb3e3fcb7 | 4727251e0cd73359b15b664c3170e5d754078599 | /src/data/finsupp/fin.lean | e8ab345a5d6c90988b3119ce8c9184684ac96260 | [
"Apache-2.0"
] | permissive | Vierkantor/mathlib | 0ea59ac32a3a43c93c44d70f441c4ee810ccceca | 83bc3b9ce9b13910b57bda6b56222495ebd31c2f | refs/heads/master | 1,658,323,012,449 | 1,652,256,003,000 | 1,652,256,003,000 | 209,296,341 | 0 | 1 | Apache-2.0 | 1,568,807,655,000 | 1,568,807,655,000 | null | UTF-8 | Lean | false | false | 2,828 | lean | /-
Copyright (c) 2021 Ivan Sadofschi Costa. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Ivan Sadofschi Costa
-/
import data.fin.tuple
import data.finsupp.basic
/-!
# `cons` and `tail` for maps `fin n →₀ M`
We interpret maps `fin n →₀ M` as `n`-tuples of elements of `M`,
We define the following operations:
* `finsupp.tail` : the tail of a map `fin (n + 1) →₀ M`, i.e., its last `n` entries;
* `finsupp.cons` : adding an element at the beginning of an `n`-tuple, to get an `n + 1`-tuple;
In this context, we prove some usual properties of `tail` and `cons`, analogous to those of
`data.fin.tuple.basic`.
-/
noncomputable theory
namespace finsupp
variables {n : ℕ} (i : fin n) {M : Type*} [has_zero M] (y : M)
(t : fin (n + 1) →₀ M) (s : fin n →₀ M)
/-- `tail` for maps `fin (n + 1) →₀ M`. See `fin.tail` for more details. -/
def tail (s : fin (n + 1) →₀ M) : fin n →₀ M :=
finsupp.equiv_fun_on_fintype.inv_fun (fin.tail s.to_fun)
/-- `cons` for maps `fin n →₀ M`. See `fin.cons` for more details. -/
def cons (y : M) (s : fin n →₀ M) : fin (n + 1) →₀ M :=
finsupp.equiv_fun_on_fintype.inv_fun (fin.cons y s.to_fun)
lemma tail_apply : tail t i = t i.succ :=
begin
simp only [tail, equiv_fun_on_fintype_symm_apply_to_fun, equiv.inv_fun_as_coe],
refl,
end
@[simp] lemma cons_zero : cons y s 0 = y :=
by simp [cons, finsupp.equiv_fun_on_fintype]
@[simp] lemma cons_succ : cons y s i.succ = s i :=
begin
simp only [finsupp.cons, fin.cons, finsupp.equiv_fun_on_fintype, fin.cases_succ, finsupp.coe_mk],
refl,
end
@[simp] lemma tail_cons : tail (cons y s) = s :=
begin
simp only [finsupp.cons, fin.cons, finsupp.tail, fin.tail],
ext,
simp only [equiv_fun_on_fintype_symm_apply_to_fun, equiv.inv_fun_as_coe,
finsupp.coe_mk, fin.cases_succ, equiv_fun_on_fintype],
refl,
end
@[simp] lemma cons_tail : cons (t 0) (tail t) = t :=
begin
ext,
by_cases c_a : a = 0,
{ rw [c_a, cons_zero] },
{ rw [←fin.succ_pred a c_a, cons_succ, ←tail_apply] },
end
@[simp] lemma cons_zero_zero : cons 0 (0 : fin n →₀ M) = 0 :=
begin
ext,
by_cases c : a = 0,
{ simp [c] },
{ rw [←fin.succ_pred a c, cons_succ],
simp },
end
variables {s} {y}
lemma cons_ne_zero_of_left (h : y ≠ 0) : cons y s ≠ 0 :=
begin
contrapose! h with c,
rw [←cons_zero y s, c, finsupp.coe_zero, pi.zero_apply],
end
lemma cons_ne_zero_of_right (h : s ≠ 0) : cons y s ≠ 0 :=
begin
contrapose! h with c,
ext,
simp [ ← cons_succ a y s, c],
end
lemma cons_ne_zero_iff : cons y s ≠ 0 ↔ y ≠ 0 ∨ s ≠ 0 :=
begin
refine ⟨λ h, _, λ h, h.cases_on cons_ne_zero_of_left cons_ne_zero_of_right⟩,
refine imp_iff_not_or.1 (λ h' c, h _),
rw [h', c, finsupp.cons_zero_zero],
end
end finsupp
|
c81f94af2d94fcda294fa635f6401a72db4d5b4c | 626e312b5c1cb2d88fca108f5933076012633192 | /src/analysis/calculus/times_cont_diff.lean | 117676c10a0288069ccbc07f4d579c20c898506f | [
"Apache-2.0"
] | permissive | Bioye97/mathlib | 9db2f9ee54418d29dd06996279ba9dc874fd6beb | 782a20a27ee83b523f801ff34efb1a9557085019 | refs/heads/master | 1,690,305,956,488 | 1,631,067,774,000 | 1,631,067,774,000 | null | 0 | 0 | null | null | null | null | UTF-8 | Lean | false | false | 142,338 | lean | /-
Copyright (c) 2019 Sébastien Gouëzel. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Sébastien Gouëzel
-/
import analysis.calculus.mean_value
import analysis.normed_space.multilinear
/-!
# Higher differentiability
A function is `C^1` on a domain if it is differentiable there, and its derivative is continuous.
By induction, it is `C^n` if it is `C^{n-1}` and its (n-1)-th derivative is `C^1` there or,
equivalently, if it is `C^1` and its derivative is `C^{n-1}`.
Finally, it is `C^∞` if it is `C^n` for all n.
We formalize these notions by defining iteratively the `n+1`-th derivative of a function as the
derivative of the `n`-th derivative. It is called `iterated_fderiv 𝕜 n f x` where `𝕜` is the
field, `n` is the number of iterations, `f` is the function and `x` is the point, and it is given
as an `n`-multilinear map. We also define a version `iterated_fderiv_within` relative to a domain,
as well as predicates `times_cont_diff_within_at`, `times_cont_diff_at`, `times_cont_diff_on` and
`times_cont_diff` saying that the function is `C^n` within a set at a point, at a point, on a set
and on the whole space respectively.
To avoid the issue of choice when choosing a derivative in sets where the derivative is not
necessarily unique, `times_cont_diff_on` is not defined directly in terms of the
regularity of the specific choice `iterated_fderiv_within 𝕜 n f s` inside `s`, but in terms of the
existence of a nice sequence of derivatives, expressed with a predicate
`has_ftaylor_series_up_to_on`.
We prove basic properties of these notions.
## Main definitions and results
Let `f : E → F` be a map between normed vector spaces over a nondiscrete normed field `𝕜`.
* `has_ftaylor_series_up_to n f p`: expresses that the formal multilinear series `p` is a sequence
of iterated derivatives of `f`, up to the `n`-th term (where `n` is a natural number or `∞`).
* `has_ftaylor_series_up_to_on n f p s`: same thing, but inside a set `s`. The notion of derivative
is now taken inside `s`. In particular, derivatives don't have to be unique.
* `times_cont_diff 𝕜 n f`: expresses that `f` is `C^n`, i.e., it admits a Taylor series up to
rank `n`.
* `times_cont_diff_on 𝕜 n f s`: expresses that `f` is `C^n` in `s`.
* `times_cont_diff_at 𝕜 n f x`: expresses that `f` is `C^n` around `x`.
* `times_cont_diff_within_at 𝕜 n f s x`: expresses that `f` is `C^n` around `x` within the set `s`.
* `iterated_fderiv_within 𝕜 n f s x` is an `n`-th derivative of `f` over the field `𝕜` on the
set `s` at the point `x`. It is a continuous multilinear map from `E^n` to `F`, defined as a
derivative within `s` of `iterated_fderiv_within 𝕜 (n-1) f s` if one exists, and `0` otherwise.
* `iterated_fderiv 𝕜 n f x` is the `n`-th derivative of `f` over the field `𝕜` at the point `x`.
It is a continuous multilinear map from `E^n` to `F`, defined as a derivative of
`iterated_fderiv 𝕜 (n-1) f` if one exists, and `0` otherwise.
In sets of unique differentiability, `times_cont_diff_on 𝕜 n f s` can be expressed in terms of the
properties of `iterated_fderiv_within 𝕜 m f s` for `m ≤ n`. In the whole space,
`times_cont_diff 𝕜 n f` can be expressed in terms of the properties of `iterated_fderiv 𝕜 m f`
for `m ≤ n`.
We also prove that the usual operations (addition, multiplication, difference, composition, and
so on) preserve `C^n` functions.
## Implementation notes
The definitions in this file are designed to work on any field `𝕜`. They are sometimes slightly more
complicated than the naive definitions one would guess from the intuition over the real or complex
numbers, but they are designed to circumvent the lack of gluing properties and partitions of unity
in general. In the usual situations, they coincide with the usual definitions.
### Definition of `C^n` functions in domains
One could define `C^n` functions in a domain `s` by fixing an arbitrary choice of derivatives (this
is what we do with `iterated_fderiv_within`) and requiring that all these derivatives up to `n` are
continuous. If the derivative is not unique, this could lead to strange behavior like two `C^n`
functions `f` and `g` on `s` whose sum is not `C^n`. A better definition is thus to say that a
function is `C^n` inside `s` if it admits a sequence of derivatives up to `n` inside `s`.
This definition still has the problem that a function which is locally `C^n` would not need to
be `C^n`, as different choices of sequences of derivatives around different points might possibly
not be glued together to give a globally defined sequence of derivatives. (Note that this issue
can not happen over reals, thanks to partition of unity, but the behavior over a general field is
not so clear, and we want a definition for general fields). Also, there are locality
problems for the order parameter: one could image a function which, for each `n`, has a nice
sequence of derivatives up to order `n`, but they do not coincide for varying `n` and can therefore
not be glued to give rise to an infinite sequence of derivatives. This would give a function
which is `C^n` for all `n`, but not `C^∞`. We solve this issue by putting locality conditions
in space and order in our definition of `times_cont_diff_within_at` and `times_cont_diff_on`.
The resulting definition is slightly more complicated to work with (in fact not so much), but it
gives rise to completely satisfactory theorems.
For instance, with this definition, a real function which is `C^m` (but not better) on `(-1/m, 1/m)`
for each natural `m` is by definition `C^∞` at `0`.
There is another issue with the definition of `times_cont_diff_within_at 𝕜 n f s x`. We can
require the existence and good behavior of derivatives up to order `n` on a neighborhood of `x`
within `s`. However, this does not imply continuity or differentiability within `s` of the function
at `x` when `x` does not belong to `s`. Therefore, we require such existence and good behavior on
a neighborhood of `x` within `s ∪ {x}` (which appears as `insert x s` in this file).
### Side of the composition, and universe issues
With a naïve direct definition, the `n`-th derivative of a function belongs to the space
`E →L[𝕜] (E →L[𝕜] (E ... F)...)))` where there are n iterations of `E →L[𝕜]`. This space
may also be seen as the space of continuous multilinear functions on `n` copies of `E` with
values in `F`, by uncurrying. This is the point of view that is usually adopted in textbooks,
and that we also use. This means that the definition and the first proofs are slightly involved,
as one has to keep track of the uncurrying operation. The uncurrying can be done from the
left or from the right, amounting to defining the `n+1`-th derivative either as the derivative of
the `n`-th derivative, or as the `n`-th derivative of the derivative.
For proofs, it would be more convenient to use the latter approach (from the right),
as it means to prove things at the `n+1`-th step we only need to understand well enough the
derivative in `E →L[𝕜] F` (contrary to the approach from the left, where one would need to know
enough on the `n`-th derivative to deduce things on the `n+1`-th derivative).
However, the definition from the right leads to a universe polymorphism problem: if we define
`iterated_fderiv 𝕜 (n + 1) f x = iterated_fderiv 𝕜 n (fderiv 𝕜 f) x` by induction, we need to
generalize over all spaces (as `f` and `fderiv 𝕜 f` don't take values in the same space). It is
only possible to generalize over all spaces in some fixed universe in an inductive definition.
For `f : E → F`, then `fderiv 𝕜 f` is a map `E → (E →L[𝕜] F)`. Therefore, the definition will only
work if `F` and `E →L[𝕜] F` are in the same universe.
This issue does not appear with the definition from the left, where one does not need to generalize
over all spaces. Therefore, we use the definition from the left. This means some proofs later on
become a little bit more complicated: to prove that a function is `C^n`, the most efficient approach
is to exhibit a formula for its `n`-th derivative and prove it is continuous (contrary to the
inductive approach where one would prove smoothness statements without giving a formula for the
derivative). In the end, this approach is still satisfactory as it is good to have formulas for the
iterated derivatives in various constructions.
One point where we depart from this explicit approach is in the proof of smoothness of a
composition: there is a formula for the `n`-th derivative of a composition (Faà di Bruno's formula),
but it is very complicated and barely usable, while the inductive proof is very simple. Thus, we
give the inductive proof. As explained above, it works by generalizing over the target space, hence
it only works well if all spaces belong to the same universe. To get the general version, we lift
things to a common universe using a trick.
### Variables management
The textbook definitions and proofs use various identifications and abuse of notations, for instance
when saying that the natural space in which the derivative lives, i.e.,
`E →L[𝕜] (E →L[𝕜] ( ... →L[𝕜] F))`, is the same as a space of multilinear maps. When doing things
formally, we need to provide explicit maps for these identifications, and chase some diagrams to see
everything is compatible with the identifications. In particular, one needs to check that taking the
derivative and then doing the identification, or first doing the identification and then taking the
derivative, gives the same result. The key point for this is that taking the derivative commutes
with continuous linear equivalences. Therefore, we need to implement all our identifications with
continuous linear equivs.
## Notations
We use the notation `E [×n]→L[𝕜] F` for the space of continuous multilinear maps on `E^n` with
values in `F`. This is the space in which the `n`-th derivative of a function from `E` to `F` lives.
In this file, we denote `⊤ : with_top ℕ` with `∞`.
## Tags
derivative, differentiability, higher derivative, `C^n`, multilinear, Taylor series, formal series
-/
noncomputable theory
open_locale classical big_operators nnreal
local notation `∞` := (⊤ : with_top ℕ)
universes u v w
local attribute [instance, priority 1001]
normed_group.to_add_comm_group normed_space.to_module add_comm_group.to_add_comm_monoid
open set fin filter
open_locale topological_space
variables {𝕜 : Type*} [nondiscrete_normed_field 𝕜]
{E : Type*} [normed_group E] [normed_space 𝕜 E]
{F : Type*} [normed_group F] [normed_space 𝕜 F]
{G : Type*} [normed_group G] [normed_space 𝕜 G]
{s s₁ t u : set E} {f f₁ : E → F} {g : F → G} {x : E} {c : F}
{b : E × F → G}
/-! ### Functions with a Taylor series on a domain -/
variable {p : E → formal_multilinear_series 𝕜 E F}
/-- `has_ftaylor_series_up_to_on n f p s` registers the fact that `p 0 = f` and `p (m+1)` is a
derivative of `p m` for `m < n`, and is continuous for `m ≤ n`. This is a predicate analogous to
`has_fderiv_within_at` but for higher order derivatives. -/
structure has_ftaylor_series_up_to_on (n : with_top ℕ)
(f : E → F) (p : E → formal_multilinear_series 𝕜 E F) (s : set E) : Prop :=
(zero_eq : ∀ x ∈ s, (p x 0).uncurry0 = f x)
(fderiv_within : ∀ (m : ℕ) (hm : (m : with_top ℕ) < n), ∀ x ∈ s,
has_fderiv_within_at (λ y, p y m) (p x m.succ).curry_left s x)
(cont : ∀ (m : ℕ) (hm : (m : with_top ℕ) ≤ n), continuous_on (λ x, p x m) s)
lemma has_ftaylor_series_up_to_on.zero_eq' {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) {x : E} (hx : x ∈ s) :
p x 0 = (continuous_multilinear_curry_fin0 𝕜 E F).symm (f x) :=
by { rw ← h.zero_eq x hx, symmetry, exact continuous_multilinear_map.uncurry0_curry0 _ }
/-- If two functions coincide on a set `s`, then a Taylor series for the first one is as well a
Taylor series for the second one. -/
lemma has_ftaylor_series_up_to_on.congr {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) (h₁ : ∀ x ∈ s, f₁ x = f x) :
has_ftaylor_series_up_to_on n f₁ p s :=
begin
refine ⟨λ x hx, _, h.fderiv_within, h.cont⟩,
rw h₁ x hx,
exact h.zero_eq x hx
end
lemma has_ftaylor_series_up_to_on.mono {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) {t : set E} (hst : t ⊆ s) :
has_ftaylor_series_up_to_on n f p t :=
⟨λ x hx, h.zero_eq x (hst hx),
λ m hm x hx, (h.fderiv_within m hm x (hst hx)).mono hst,
λ m hm, (h.cont m hm).mono hst⟩
lemma has_ftaylor_series_up_to_on.of_le {m n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) (hmn : m ≤ n) :
has_ftaylor_series_up_to_on m f p s :=
⟨h.zero_eq,
λ k hk x hx, h.fderiv_within k (lt_of_lt_of_le hk hmn) x hx,
λ k hk, h.cont k (le_trans hk hmn)⟩
lemma has_ftaylor_series_up_to_on.continuous_on {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) : continuous_on f s :=
begin
have := (h.cont 0 bot_le).congr (λ x hx, (h.zero_eq' hx).symm),
rwa linear_isometry_equiv.comp_continuous_on_iff at this
end
lemma has_ftaylor_series_up_to_on_zero_iff :
has_ftaylor_series_up_to_on 0 f p s ↔ continuous_on f s ∧ (∀ x ∈ s, (p x 0).uncurry0 = f x) :=
begin
refine ⟨λ H, ⟨H.continuous_on, H.zero_eq⟩,
λ H, ⟨H.2, λ m hm, false.elim (not_le.2 hm bot_le), _⟩⟩,
assume m hm,
obtain rfl : m = 0, by exact_mod_cast (hm.antisymm (zero_le _)),
have : ∀ x ∈ s, p x 0 = (continuous_multilinear_curry_fin0 𝕜 E F).symm (f x),
by { assume x hx, rw ← H.2 x hx, symmetry, exact continuous_multilinear_map.uncurry0_curry0 _ },
rw [continuous_on_congr this, linear_isometry_equiv.comp_continuous_on_iff],
exact H.1
end
lemma has_ftaylor_series_up_to_on_top_iff :
(has_ftaylor_series_up_to_on ∞ f p s) ↔ (∀ (n : ℕ), has_ftaylor_series_up_to_on n f p s) :=
begin
split,
{ assume H n, exact H.of_le le_top },
{ assume H,
split,
{ exact (H 0).zero_eq },
{ assume m hm,
apply (H m.succ).fderiv_within m (with_top.coe_lt_coe.2 (lt_add_one m)) },
{ assume m hm,
apply (H m).cont m (le_refl _) } }
end
/-- If a function has a Taylor series at order at least `1`, then the term of order `1` of this
series is a derivative of `f`. -/
lemma has_ftaylor_series_up_to_on.has_fderiv_within_at {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) (hn : 1 ≤ n) (hx : x ∈ s) :
has_fderiv_within_at f (continuous_multilinear_curry_fin1 𝕜 E F (p x 1)) s x :=
begin
have A : ∀ y ∈ s, f y = (continuous_multilinear_curry_fin0 𝕜 E F) (p y 0),
{ assume y hy, rw ← h.zero_eq y hy, refl },
suffices H : has_fderiv_within_at
(λ y, continuous_multilinear_curry_fin0 𝕜 E F (p y 0))
(continuous_multilinear_curry_fin1 𝕜 E F (p x 1)) s x,
by exact H.congr A (A x hx),
rw linear_isometry_equiv.comp_has_fderiv_within_at_iff',
have : ((0 : ℕ) : with_top ℕ) < n :=
lt_of_lt_of_le (with_top.coe_lt_coe.2 nat.zero_lt_one) hn,
convert h.fderiv_within _ this x hx,
ext y v,
change (p x 1) (snoc 0 y) = (p x 1) (cons y v),
unfold_coes,
congr' with i,
rw unique.eq_default i,
refl
end
lemma has_ftaylor_series_up_to_on.differentiable_on {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) (hn : 1 ≤ n) : differentiable_on 𝕜 f s :=
λ x hx, (h.has_fderiv_within_at hn hx).differentiable_within_at
/-- If a function has a Taylor series at order at least `1` on a neighborhood of `x`, then the term
of order `1` of this series is a derivative of `f` at `x`. -/
lemma has_ftaylor_series_up_to_on.has_fderiv_at {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) (hn : 1 ≤ n) (hx : s ∈ 𝓝 x) :
has_fderiv_at f (continuous_multilinear_curry_fin1 𝕜 E F (p x 1)) x :=
(h.has_fderiv_within_at hn (mem_of_mem_nhds hx)).has_fderiv_at hx
/-- If a function has a Taylor series at order at least `1` on a neighborhood of `x`, then
in a neighborhood of `x`, the term of order `1` of this series is a derivative of `f`. -/
lemma has_ftaylor_series_up_to_on.eventually_has_fderiv_at {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) (hn : 1 ≤ n) (hx : s ∈ 𝓝 x) :
∀ᶠ y in 𝓝 x, has_fderiv_at f (continuous_multilinear_curry_fin1 𝕜 E F (p y 1)) y :=
(eventually_eventually_nhds.2 hx).mono $ λ y hy, h.has_fderiv_at hn hy
/-- If a function has a Taylor series at order at least `1` on a neighborhood of `x`, then
it is differentiable at `x`. -/
lemma has_ftaylor_series_up_to_on.differentiable_at {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s) (hn : 1 ≤ n) (hx : s ∈ 𝓝 x) :
differentiable_at 𝕜 f x :=
(h.has_fderiv_at hn hx).differentiable_at
/-- `p` is a Taylor series of `f` up to `n+1` if and only if `p` is a Taylor series up to `n`, and
`p (n + 1)` is a derivative of `p n`. -/
theorem has_ftaylor_series_up_to_on_succ_iff_left {n : ℕ} :
has_ftaylor_series_up_to_on (n + 1) f p s ↔
has_ftaylor_series_up_to_on n f p s
∧ (∀ x ∈ s, has_fderiv_within_at (λ y, p y n) (p x n.succ).curry_left s x)
∧ continuous_on (λ x, p x (n + 1)) s :=
begin
split,
{ assume h,
exact ⟨h.of_le (with_top.coe_le_coe.2 (nat.le_succ n)),
h.fderiv_within _ (with_top.coe_lt_coe.2 (lt_add_one n)),
h.cont (n + 1) (le_refl _)⟩ },
{ assume h,
split,
{ exact h.1.zero_eq },
{ assume m hm,
by_cases h' : m < n,
{ exact h.1.fderiv_within m (with_top.coe_lt_coe.2 h') },
{ have : m = n := nat.eq_of_lt_succ_of_not_lt (with_top.coe_lt_coe.1 hm) h',
rw this,
exact h.2.1 } },
{ assume m hm,
by_cases h' : m ≤ n,
{ apply h.1.cont m (with_top.coe_le_coe.2 h') },
{ have : m = (n + 1) := le_antisymm (with_top.coe_le_coe.1 hm) (not_le.1 h'),
rw this,
exact h.2.2 } } }
end
/-- `p` is a Taylor series of `f` up to `n+1` if and only if `p.shift` is a Taylor series up to `n`
for `p 1`, which is a derivative of `f`. -/
theorem has_ftaylor_series_up_to_on_succ_iff_right {n : ℕ} :
has_ftaylor_series_up_to_on ((n + 1) : ℕ) f p s ↔
(∀ x ∈ s, (p x 0).uncurry0 = f x)
∧ (∀ x ∈ s, has_fderiv_within_at (λ y, p y 0) (p x 1).curry_left s x)
∧ has_ftaylor_series_up_to_on n
(λ x, continuous_multilinear_curry_fin1 𝕜 E F (p x 1)) (λ x, (p x).shift) s :=
begin
split,
{ assume H,
refine ⟨H.zero_eq, H.fderiv_within 0 (with_top.coe_lt_coe.2 (nat.succ_pos n)), _⟩,
split,
{ assume x hx, refl },
{ assume m (hm : (m : with_top ℕ) < n) x (hx : x ∈ s),
have A : (m.succ : with_top ℕ) < n.succ,
by { rw with_top.coe_lt_coe at ⊢ hm, exact nat.lt_succ_iff.mpr hm },
change has_fderiv_within_at
((continuous_multilinear_curry_right_equiv' 𝕜 m E F).symm
∘ (λ (y : E), p y m.succ))
(p x m.succ.succ).curry_right.curry_left s x,
rw linear_isometry_equiv.comp_has_fderiv_within_at_iff',
convert H.fderiv_within _ A x hx,
ext y v,
change (p x m.succ.succ) (snoc (cons y (init v)) (v (last _)))
= (p x (nat.succ (nat.succ m))) (cons y v),
rw [← cons_snoc_eq_snoc_cons, snoc_init_self] },
{ assume m (hm : (m : with_top ℕ) ≤ n),
have A : (m.succ : with_top ℕ) ≤ n.succ,
by { rw with_top.coe_le_coe at ⊢ hm, exact nat.pred_le_iff.mp hm },
change continuous_on ((continuous_multilinear_curry_right_equiv' 𝕜 m E F).symm
∘ (λ (y : E), p y m.succ)) s,
rw linear_isometry_equiv.comp_continuous_on_iff,
exact H.cont _ A } },
{ rintros ⟨Hzero_eq, Hfderiv_zero, Htaylor⟩,
split,
{ exact Hzero_eq },
{ assume m (hm : (m : with_top ℕ) < n.succ) x (hx : x ∈ s),
cases m,
{ exact Hfderiv_zero x hx },
{ have A : (m : with_top ℕ) < n,
by { rw with_top.coe_lt_coe at hm ⊢, exact nat.lt_of_succ_lt_succ hm },
have : has_fderiv_within_at ((continuous_multilinear_curry_right_equiv' 𝕜 m E F).symm
∘ (λ (y : E), p y m.succ)) ((p x).shift m.succ).curry_left s x :=
Htaylor.fderiv_within _ A x hx,
rw linear_isometry_equiv.comp_has_fderiv_within_at_iff' at this,
convert this,
ext y v,
change (p x (nat.succ (nat.succ m))) (cons y v)
= (p x m.succ.succ) (snoc (cons y (init v)) (v (last _))),
rw [← cons_snoc_eq_snoc_cons, snoc_init_self] } },
{ assume m (hm : (m : with_top ℕ) ≤ n.succ),
cases m,
{ have : differentiable_on 𝕜 (λ x, p x 0) s :=
λ x hx, (Hfderiv_zero x hx).differentiable_within_at,
exact this.continuous_on },
{ have A : (m : with_top ℕ) ≤ n,
by { rw with_top.coe_le_coe at hm ⊢, exact nat.lt_succ_iff.mp hm },
have : continuous_on ((continuous_multilinear_curry_right_equiv' 𝕜 m E F).symm
∘ (λ (y : E), p y m.succ)) s :=
Htaylor.cont _ A,
rwa linear_isometry_equiv.comp_continuous_on_iff at this } } }
end
/-! ### Smooth functions within a set around a point -/
variable (𝕜)
/-- A function is continuously differentiable up to order `n` within a set `s` at a point `x` if
it admits continuous derivatives up to order `n` in a neighborhood of `x` in `s ∪ {x}`.
For `n = ∞`, we only require that this holds up to any finite order (where the neighborhood may
depend on the finite order we consider).
For instance, a real function which is `C^m` on `(-1/m, 1/m)` for each natural `m`, but not
better, is `C^∞` at `0` within `univ`.
-/
def times_cont_diff_within_at (n : with_top ℕ) (f : E → F) (s : set E) (x : E) :=
∀ (m : ℕ), (m : with_top ℕ) ≤ n →
∃ u ∈ 𝓝[insert x s] x, ∃ p : E → formal_multilinear_series 𝕜 E F,
has_ftaylor_series_up_to_on m f p u
variable {𝕜}
lemma times_cont_diff_within_at_nat {n : ℕ} :
times_cont_diff_within_at 𝕜 n f s x ↔
∃ u ∈ 𝓝[insert x s] x, ∃ p : E → formal_multilinear_series 𝕜 E F,
has_ftaylor_series_up_to_on n f p u :=
⟨λ H, H n (le_refl _), λ ⟨u, hu, p, hp⟩ m hm, ⟨u, hu, p, hp.of_le hm⟩⟩
lemma times_cont_diff_within_at.of_le {m n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) (hmn : m ≤ n) :
times_cont_diff_within_at 𝕜 m f s x :=
λ k hk, h k (le_trans hk hmn)
lemma times_cont_diff_within_at_iff_forall_nat_le {n : with_top ℕ} :
times_cont_diff_within_at 𝕜 n f s x ↔ ∀ m : ℕ, ↑m ≤ n → times_cont_diff_within_at 𝕜 m f s x :=
⟨λ H m hm, H.of_le hm, λ H m hm, H m hm _ le_rfl⟩
lemma times_cont_diff_within_at_top :
times_cont_diff_within_at 𝕜 ∞ f s x ↔ ∀ (n : ℕ), times_cont_diff_within_at 𝕜 n f s x :=
times_cont_diff_within_at_iff_forall_nat_le.trans $ by simp only [forall_prop_of_true, le_top]
lemma times_cont_diff_within_at.continuous_within_at {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) : continuous_within_at f s x :=
begin
rcases h 0 bot_le with ⟨u, hu, p, H⟩,
rw [mem_nhds_within_insert] at hu,
exact (H.continuous_on.continuous_within_at hu.1).mono_of_mem hu.2
end
lemma times_cont_diff_within_at.congr_of_eventually_eq {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) (h₁ : f₁ =ᶠ[𝓝[s] x] f) (hx : f₁ x = f x) :
times_cont_diff_within_at 𝕜 n f₁ s x :=
λ m hm, let ⟨u, hu, p, H⟩ := h m hm in
⟨{x ∈ u | f₁ x = f x}, filter.inter_mem hu (mem_nhds_within_insert.2 ⟨hx, h₁⟩), p,
(H.mono (sep_subset _ _)).congr (λ _, and.right)⟩
lemma times_cont_diff_within_at.congr_of_eventually_eq' {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) (h₁ : f₁ =ᶠ[𝓝[s] x] f) (hx : x ∈ s) :
times_cont_diff_within_at 𝕜 n f₁ s x :=
h.congr_of_eventually_eq h₁ $ h₁.self_of_nhds_within hx
lemma filter.eventually_eq.times_cont_diff_within_at_iff {n : with_top ℕ}
(h₁ : f₁ =ᶠ[𝓝[s] x] f) (hx : f₁ x = f x) :
times_cont_diff_within_at 𝕜 n f₁ s x ↔ times_cont_diff_within_at 𝕜 n f s x :=
⟨λ H, times_cont_diff_within_at.congr_of_eventually_eq H h₁.symm hx.symm,
λ H, H.congr_of_eventually_eq h₁ hx⟩
lemma times_cont_diff_within_at.congr {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) (h₁ : ∀ y ∈ s, f₁ y = f y) (hx : f₁ x = f x) :
times_cont_diff_within_at 𝕜 n f₁ s x :=
h.congr_of_eventually_eq (filter.eventually_eq_of_mem self_mem_nhds_within h₁) hx
lemma times_cont_diff_within_at.congr' {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) (h₁ : ∀ y ∈ s, f₁ y = f y) (hx : x ∈ s) :
times_cont_diff_within_at 𝕜 n f₁ s x :=
h.congr h₁ (h₁ _ hx)
lemma times_cont_diff_within_at.mono_of_mem {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) {t : set E} (hst : s ∈ 𝓝[t] x) :
times_cont_diff_within_at 𝕜 n f t x :=
begin
assume m hm,
rcases h m hm with ⟨u, hu, p, H⟩,
exact ⟨u, nhds_within_le_of_mem (insert_mem_nhds_within_insert hst) hu, p, H⟩
end
lemma times_cont_diff_within_at.mono {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) {t : set E} (hst : t ⊆ s) :
times_cont_diff_within_at 𝕜 n f t x :=
h.mono_of_mem $ filter.mem_of_superset self_mem_nhds_within hst
lemma times_cont_diff_within_at.congr_nhds {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) {t : set E} (hst : 𝓝[s] x = 𝓝[t] x) :
times_cont_diff_within_at 𝕜 n f t x :=
h.mono_of_mem $ hst ▸ self_mem_nhds_within
lemma times_cont_diff_within_at_congr_nhds {n : with_top ℕ} {t : set E} (hst : 𝓝[s] x = 𝓝[t] x) :
times_cont_diff_within_at 𝕜 n f s x ↔ times_cont_diff_within_at 𝕜 n f t x :=
⟨λ h, h.congr_nhds hst, λ h, h.congr_nhds hst.symm⟩
lemma times_cont_diff_within_at_inter' {n : with_top ℕ} (h : t ∈ 𝓝[s] x) :
times_cont_diff_within_at 𝕜 n f (s ∩ t) x ↔ times_cont_diff_within_at 𝕜 n f s x :=
times_cont_diff_within_at_congr_nhds $ eq.symm $ nhds_within_restrict'' _ h
lemma times_cont_diff_within_at_inter {n : with_top ℕ} (h : t ∈ 𝓝 x) :
times_cont_diff_within_at 𝕜 n f (s ∩ t) x ↔ times_cont_diff_within_at 𝕜 n f s x :=
times_cont_diff_within_at_inter' (mem_nhds_within_of_mem_nhds h)
/-- If a function is `C^n` within a set at a point, with `n ≥ 1`, then it is differentiable
within this set at this point. -/
lemma times_cont_diff_within_at.differentiable_within_at' {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) (hn : 1 ≤ n) :
differentiable_within_at 𝕜 f (insert x s) x :=
begin
rcases h 1 hn with ⟨u, hu, p, H⟩,
rcases mem_nhds_within.1 hu with ⟨t, t_open, xt, tu⟩,
rw inter_comm at tu,
have := ((H.mono tu).differentiable_on (le_refl _)) x ⟨mem_insert x s, xt⟩,
exact (differentiable_within_at_inter (is_open.mem_nhds t_open xt)).1 this,
end
lemma times_cont_diff_within_at.differentiable_within_at {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) (hn : 1 ≤ n) :
differentiable_within_at 𝕜 f s x :=
(h.differentiable_within_at' hn).mono (subset_insert x s)
/-- A function is `C^(n + 1)` on a domain iff locally, it has a derivative which is `C^n`. -/
theorem times_cont_diff_within_at_succ_iff_has_fderiv_within_at {n : ℕ} :
times_cont_diff_within_at 𝕜 ((n + 1) : ℕ) f s x
↔ ∃ u ∈ 𝓝[insert x s] x, ∃ f' : E → (E →L[𝕜] F),
(∀ x ∈ u, has_fderiv_within_at f (f' x) u x) ∧ (times_cont_diff_within_at 𝕜 n f' u x) :=
begin
split,
{ assume h,
rcases h n.succ (le_refl _) with ⟨u, hu, p, Hp⟩,
refine ⟨u, hu, λ y, (continuous_multilinear_curry_fin1 𝕜 E F) (p y 1),
λ y hy, Hp.has_fderiv_within_at (with_top.coe_le_coe.2 (nat.le_add_left 1 n)) hy, _⟩,
assume m hm,
refine ⟨u, _, λ (y : E), (p y).shift, _⟩,
{ convert self_mem_nhds_within,
have : x ∈ insert x s, by simp,
exact (insert_eq_of_mem (mem_of_mem_nhds_within this hu)) },
{ rw has_ftaylor_series_up_to_on_succ_iff_right at Hp,
exact Hp.2.2.of_le hm } },
{ rintros ⟨u, hu, f', f'_eq_deriv, Hf'⟩,
rw times_cont_diff_within_at_nat,
rcases Hf' n (le_refl _) with ⟨v, hv, p', Hp'⟩,
refine ⟨v ∩ u, _, λ x, (p' x).unshift (f x), _⟩,
{ apply filter.inter_mem _ hu,
apply nhds_within_le_of_mem hu,
exact nhds_within_mono _ (subset_insert x u) hv },
{ rw has_ftaylor_series_up_to_on_succ_iff_right,
refine ⟨λ y hy, rfl, λ y hy, _, _⟩,
{ change has_fderiv_within_at (λ z, (continuous_multilinear_curry_fin0 𝕜 E F).symm (f z))
((formal_multilinear_series.unshift (p' y) (f y) 1).curry_left) (v ∩ u) y,
rw linear_isometry_equiv.comp_has_fderiv_within_at_iff',
convert (f'_eq_deriv y hy.2).mono (inter_subset_right v u),
rw ← Hp'.zero_eq y hy.1,
ext z,
change ((p' y 0) (init (@cons 0 (λ i, E) z 0))) (@cons 0 (λ i, E) z 0 (last 0))
= ((p' y 0) 0) z,
unfold_coes,
congr },
{ convert (Hp'.mono (inter_subset_left v u)).congr (λ x hx, Hp'.zero_eq x hx.1),
{ ext x y,
change p' x 0 (init (@snoc 0 (λ i : fin 1, E) 0 y)) y = p' x 0 0 y,
rw init_snoc },
{ ext x k v y,
change p' x k (init (@snoc k (λ i : fin k.succ, E) v y))
(@snoc k (λ i : fin k.succ, E) v y (last k)) = p' x k v y,
rw [snoc_last, init_snoc] } } } }
end
/-! ### Smooth functions within a set -/
variable (𝕜)
/-- A function is continuously differentiable up to `n` on `s` if, for any point `x` in `s`, it
admits continuous derivatives up to order `n` on a neighborhood of `x` in `s`.
For `n = ∞`, we only require that this holds up to any finite order (where the neighborhood may
depend on the finite order we consider).
-/
definition times_cont_diff_on (n : with_top ℕ) (f : E → F) (s : set E) :=
∀ x ∈ s, times_cont_diff_within_at 𝕜 n f s x
variable {𝕜}
lemma times_cont_diff_on.times_cont_diff_within_at {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f s) (hx : x ∈ s) :
times_cont_diff_within_at 𝕜 n f s x :=
h x hx
lemma times_cont_diff_within_at.times_cont_diff_on {n : with_top ℕ} {m : ℕ}
(hm : (m : with_top ℕ) ≤ n) (h : times_cont_diff_within_at 𝕜 n f s x) :
∃ u ∈ 𝓝[insert x s] x, u ⊆ insert x s ∧ times_cont_diff_on 𝕜 m f u :=
begin
rcases h m hm with ⟨u, u_nhd, p, hp⟩,
refine ⟨u ∩ insert x s, filter.inter_mem u_nhd self_mem_nhds_within,
inter_subset_right _ _, _⟩,
assume y hy m' hm',
refine ⟨u ∩ insert x s, _, p, (hp.mono (inter_subset_left _ _)).of_le hm'⟩,
convert self_mem_nhds_within,
exact insert_eq_of_mem hy
end
lemma times_cont_diff_on.of_le {m n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f s) (hmn : m ≤ n) :
times_cont_diff_on 𝕜 m f s :=
λ x hx, (h x hx).of_le hmn
lemma times_cont_diff_on_iff_forall_nat_le {n : with_top ℕ} :
times_cont_diff_on 𝕜 n f s ↔ ∀ m : ℕ, ↑m ≤ n → times_cont_diff_on 𝕜 m f s :=
⟨λ H m hm, H.of_le hm, λ H x hx m hm, H m hm x hx m le_rfl⟩
lemma times_cont_diff_on_top :
times_cont_diff_on 𝕜 ∞ f s ↔ ∀ (n : ℕ), times_cont_diff_on 𝕜 n f s :=
times_cont_diff_on_iff_forall_nat_le.trans $ by simp only [le_top, forall_prop_of_true]
lemma times_cont_diff_on_all_iff_nat :
(∀ n, times_cont_diff_on 𝕜 n f s) ↔ (∀ n : ℕ, times_cont_diff_on 𝕜 n f s) :=
begin
refine ⟨λ H n, H n, _⟩,
rintro H (_|n),
exacts [times_cont_diff_on_top.2 H, H n]
end
lemma times_cont_diff_on.continuous_on {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f s) : continuous_on f s :=
λ x hx, (h x hx).continuous_within_at
lemma times_cont_diff_on.congr {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f s) (h₁ : ∀ x ∈ s, f₁ x = f x) :
times_cont_diff_on 𝕜 n f₁ s :=
λ x hx, (h x hx).congr h₁ (h₁ x hx)
lemma times_cont_diff_on_congr {n : with_top ℕ} (h₁ : ∀ x ∈ s, f₁ x = f x) :
times_cont_diff_on 𝕜 n f₁ s ↔ times_cont_diff_on 𝕜 n f s :=
⟨λ H, H.congr (λ x hx, (h₁ x hx).symm), λ H, H.congr h₁⟩
lemma times_cont_diff_on.mono {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f s) {t : set E} (hst : t ⊆ s) :
times_cont_diff_on 𝕜 n f t :=
λ x hx, (h x (hst hx)).mono hst
lemma times_cont_diff_on.congr_mono {n : with_top ℕ}
(hf : times_cont_diff_on 𝕜 n f s) (h₁ : ∀ x ∈ s₁, f₁ x = f x) (hs : s₁ ⊆ s) :
times_cont_diff_on 𝕜 n f₁ s₁ :=
(hf.mono hs).congr h₁
/-- If a function is `C^n` on a set with `n ≥ 1`, then it is differentiable there. -/
lemma times_cont_diff_on.differentiable_on {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f s) (hn : 1 ≤ n) : differentiable_on 𝕜 f s :=
λ x hx, (h x hx).differentiable_within_at hn
/-- If a function is `C^n` around each point in a set, then it is `C^n` on the set. -/
lemma times_cont_diff_on_of_locally_times_cont_diff_on {n : with_top ℕ}
(h : ∀ x ∈ s, ∃u, is_open u ∧ x ∈ u ∧ times_cont_diff_on 𝕜 n f (s ∩ u)) :
times_cont_diff_on 𝕜 n f s :=
begin
assume x xs,
rcases h x xs with ⟨u, u_open, xu, hu⟩,
apply (times_cont_diff_within_at_inter _).1 (hu x ⟨xs, xu⟩),
exact is_open.mem_nhds u_open xu
end
/-- A function is `C^(n + 1)` on a domain iff locally, it has a derivative which is `C^n`. -/
theorem times_cont_diff_on_succ_iff_has_fderiv_within_at {n : ℕ} :
times_cont_diff_on 𝕜 ((n + 1) : ℕ) f s
↔ ∀ x ∈ s, ∃ u ∈ 𝓝[insert x s] x, ∃ f' : E → (E →L[𝕜] F),
(∀ x ∈ u, has_fderiv_within_at f (f' x) u x) ∧ (times_cont_diff_on 𝕜 n f' u) :=
begin
split,
{ assume h x hx,
rcases (h x hx) n.succ (le_refl _) with ⟨u, hu, p, Hp⟩,
refine ⟨u, hu, λ y, (continuous_multilinear_curry_fin1 𝕜 E F) (p y 1),
λ y hy, Hp.has_fderiv_within_at (with_top.coe_le_coe.2 (nat.le_add_left 1 n)) hy, _⟩,
rw has_ftaylor_series_up_to_on_succ_iff_right at Hp,
assume z hz m hm,
refine ⟨u, _, λ (x : E), (p x).shift, Hp.2.2.of_le hm⟩,
convert self_mem_nhds_within,
exact insert_eq_of_mem hz, },
{ assume h x hx,
rw times_cont_diff_within_at_succ_iff_has_fderiv_within_at,
rcases h x hx with ⟨u, u_nhbd, f', hu, hf'⟩,
have : x ∈ u := mem_of_mem_nhds_within (mem_insert _ _) u_nhbd,
exact ⟨u, u_nhbd, f', hu, hf' x this⟩ }
end
/-! ### Iterated derivative within a set -/
variable (𝕜)
/--
The `n`-th derivative of a function along a set, defined inductively by saying that the `n+1`-th
derivative of `f` is the derivative of the `n`-th derivative of `f` along this set, together with
an uncurrying step to see it as a multilinear map in `n+1` variables..
-/
noncomputable def iterated_fderiv_within (n : ℕ) (f : E → F) (s : set E) :
E → (E [×n]→L[𝕜] F) :=
nat.rec_on n
(λ x, continuous_multilinear_map.curry0 𝕜 E (f x))
(λ n rec x, continuous_linear_map.uncurry_left (fderiv_within 𝕜 rec s x))
/-- Formal Taylor series associated to a function within a set. -/
def ftaylor_series_within (f : E → F) (s : set E) (x : E) : formal_multilinear_series 𝕜 E F :=
λ n, iterated_fderiv_within 𝕜 n f s x
variable {𝕜}
@[simp] lemma iterated_fderiv_within_zero_apply (m : (fin 0) → E) :
(iterated_fderiv_within 𝕜 0 f s x : ((fin 0) → E) → F) m = f x := rfl
lemma iterated_fderiv_within_zero_eq_comp :
iterated_fderiv_within 𝕜 0 f s = (continuous_multilinear_curry_fin0 𝕜 E F).symm ∘ f := rfl
lemma iterated_fderiv_within_succ_apply_left {n : ℕ} (m : fin (n + 1) → E):
(iterated_fderiv_within 𝕜 (n + 1) f s x : (fin (n + 1) → E) → F) m
= (fderiv_within 𝕜 (iterated_fderiv_within 𝕜 n f s) s x : E → (E [×n]→L[𝕜] F))
(m 0) (tail m) := rfl
/-- Writing explicitly the `n+1`-th derivative as the composition of a currying linear equiv,
and the derivative of the `n`-th derivative. -/
lemma iterated_fderiv_within_succ_eq_comp_left {n : ℕ} :
iterated_fderiv_within 𝕜 (n + 1) f s =
(continuous_multilinear_curry_left_equiv 𝕜 (λ(i : fin (n + 1)), E) F)
∘ (fderiv_within 𝕜 (iterated_fderiv_within 𝕜 n f s) s) := rfl
theorem iterated_fderiv_within_succ_apply_right {n : ℕ}
(hs : unique_diff_on 𝕜 s) (hx : x ∈ s) (m : fin (n + 1) → E) :
(iterated_fderiv_within 𝕜 (n + 1) f s x : (fin (n + 1) → E) → F) m
= iterated_fderiv_within 𝕜 n (λy, fderiv_within 𝕜 f s y) s x (init m) (m (last n)) :=
begin
induction n with n IH generalizing x,
{ rw [iterated_fderiv_within_succ_eq_comp_left, iterated_fderiv_within_zero_eq_comp,
iterated_fderiv_within_zero_apply,
function.comp_apply, linear_isometry_equiv.comp_fderiv_within _ (hs x hx)],
refl },
{ let I := continuous_multilinear_curry_right_equiv' 𝕜 n E F,
have A : ∀ y ∈ s, iterated_fderiv_within 𝕜 n.succ f s y
= (I ∘ (iterated_fderiv_within 𝕜 n (λy, fderiv_within 𝕜 f s y) s)) y,
by { assume y hy, ext m, rw @IH m y hy, refl },
calc
(iterated_fderiv_within 𝕜 (n+2) f s x : (fin (n+2) → E) → F) m =
(fderiv_within 𝕜 (iterated_fderiv_within 𝕜 n.succ f s) s x
: E → (E [×(n + 1)]→L[𝕜] F)) (m 0) (tail m) : rfl
... = (fderiv_within 𝕜 (I ∘ (iterated_fderiv_within 𝕜 n (fderiv_within 𝕜 f s) s)) s x
: E → (E [×(n + 1)]→L[𝕜] F)) (m 0) (tail m) :
by rw fderiv_within_congr (hs x hx) A (A x hx)
... = (I ∘ fderiv_within 𝕜 ((iterated_fderiv_within 𝕜 n (fderiv_within 𝕜 f s) s)) s x
: E → (E [×(n + 1)]→L[𝕜] F)) (m 0) (tail m) :
by { rw linear_isometry_equiv.comp_fderiv_within _ (hs x hx), refl }
... = (fderiv_within 𝕜 ((iterated_fderiv_within 𝕜 n (λ y, fderiv_within 𝕜 f s y) s)) s x
: E → (E [×n]→L[𝕜] (E →L[𝕜] F))) (m 0) (init (tail m)) ((tail m) (last n)) : rfl
... = iterated_fderiv_within 𝕜 (nat.succ n) (λ y, fderiv_within 𝕜 f s y) s x
(init m) (m (last (n + 1))) :
by { rw [iterated_fderiv_within_succ_apply_left, tail_init_eq_init_tail], refl } }
end
/-- Writing explicitly the `n+1`-th derivative as the composition of a currying linear equiv,
and the `n`-th derivative of the derivative. -/
lemma iterated_fderiv_within_succ_eq_comp_right {n : ℕ} (hs : unique_diff_on 𝕜 s) (hx : x ∈ s) :
iterated_fderiv_within 𝕜 (n + 1) f s x =
((continuous_multilinear_curry_right_equiv' 𝕜 n E F)
∘ (iterated_fderiv_within 𝕜 n (λy, fderiv_within 𝕜 f s y) s)) x :=
by { ext m, rw iterated_fderiv_within_succ_apply_right hs hx, refl }
@[simp] lemma iterated_fderiv_within_one_apply
(hs : unique_diff_on 𝕜 s) (hx : x ∈ s) (m : (fin 1) → E) :
(iterated_fderiv_within 𝕜 1 f s x : ((fin 1) → E) → F) m
= (fderiv_within 𝕜 f s x : E → F) (m 0) :=
by { rw [iterated_fderiv_within_succ_apply_right hs hx, iterated_fderiv_within_zero_apply], refl }
/-- If two functions coincide on a set `s` of unique differentiability, then their iterated
differentials within this set coincide. -/
lemma iterated_fderiv_within_congr {n : ℕ}
(hs : unique_diff_on 𝕜 s) (hL : ∀y∈s, f₁ y = f y) (hx : x ∈ s) :
iterated_fderiv_within 𝕜 n f₁ s x = iterated_fderiv_within 𝕜 n f s x :=
begin
induction n with n IH generalizing x,
{ ext m, simp [hL x hx] },
{ have : fderiv_within 𝕜 (λ y, iterated_fderiv_within 𝕜 n f₁ s y) s x
= fderiv_within 𝕜 (λ y, iterated_fderiv_within 𝕜 n f s y) s x :=
fderiv_within_congr (hs x hx) (λ y hy, IH hy) (IH hx),
ext m,
rw [iterated_fderiv_within_succ_apply_left, iterated_fderiv_within_succ_apply_left, this] }
end
/-- The iterated differential within a set `s` at a point `x` is not modified if one intersects
`s` with an open set containing `x`. -/
lemma iterated_fderiv_within_inter_open {n : ℕ} (hu : is_open u)
(hs : unique_diff_on 𝕜 (s ∩ u)) (hx : x ∈ s ∩ u) :
iterated_fderiv_within 𝕜 n f (s ∩ u) x = iterated_fderiv_within 𝕜 n f s x :=
begin
induction n with n IH generalizing x,
{ ext m, simp },
{ have A : fderiv_within 𝕜 (λ y, iterated_fderiv_within 𝕜 n f (s ∩ u) y) (s ∩ u) x
= fderiv_within 𝕜 (λ y, iterated_fderiv_within 𝕜 n f s y) (s ∩ u) x :=
fderiv_within_congr (hs x hx) (λ y hy, IH hy) (IH hx),
have B : fderiv_within 𝕜 (λ y, iterated_fderiv_within 𝕜 n f s y) (s ∩ u) x
= fderiv_within 𝕜 (λ y, iterated_fderiv_within 𝕜 n f s y) s x :=
fderiv_within_inter (is_open.mem_nhds hu hx.2)
((unique_diff_within_at_inter (is_open.mem_nhds hu hx.2)).1 (hs x hx)),
ext m,
rw [iterated_fderiv_within_succ_apply_left, iterated_fderiv_within_succ_apply_left, A, B] }
end
/-- The iterated differential within a set `s` at a point `x` is not modified if one intersects
`s` with a neighborhood of `x` within `s`. -/
lemma iterated_fderiv_within_inter' {n : ℕ}
(hu : u ∈ 𝓝[s] x) (hs : unique_diff_on 𝕜 s) (xs : x ∈ s) :
iterated_fderiv_within 𝕜 n f (s ∩ u) x = iterated_fderiv_within 𝕜 n f s x :=
begin
obtain ⟨v, v_open, xv, vu⟩ : ∃ v, is_open v ∧ x ∈ v ∧ v ∩ s ⊆ u := mem_nhds_within.1 hu,
have A : (s ∩ u) ∩ v = s ∩ v,
{ apply subset.antisymm (inter_subset_inter (inter_subset_left _ _) (subset.refl _)),
exact λ y ⟨ys, yv⟩, ⟨⟨ys, vu ⟨yv, ys⟩⟩, yv⟩ },
have : iterated_fderiv_within 𝕜 n f (s ∩ v) x = iterated_fderiv_within 𝕜 n f s x :=
iterated_fderiv_within_inter_open v_open (hs.inter v_open) ⟨xs, xv⟩,
rw ← this,
have : iterated_fderiv_within 𝕜 n f ((s ∩ u) ∩ v) x = iterated_fderiv_within 𝕜 n f (s ∩ u) x,
{ refine iterated_fderiv_within_inter_open v_open _ ⟨⟨xs, vu ⟨xv, xs⟩⟩, xv⟩,
rw A,
exact hs.inter v_open },
rw A at this,
rw ← this
end
/-- The iterated differential within a set `s` at a point `x` is not modified if one intersects
`s` with a neighborhood of `x`. -/
lemma iterated_fderiv_within_inter {n : ℕ}
(hu : u ∈ 𝓝 x) (hs : unique_diff_on 𝕜 s) (xs : x ∈ s) :
iterated_fderiv_within 𝕜 n f (s ∩ u) x = iterated_fderiv_within 𝕜 n f s x :=
iterated_fderiv_within_inter' (mem_nhds_within_of_mem_nhds hu) hs xs
@[simp] lemma times_cont_diff_on_zero :
times_cont_diff_on 𝕜 0 f s ↔ continuous_on f s :=
begin
refine ⟨λ H, H.continuous_on, λ H, _⟩,
assume x hx m hm,
have : (m : with_top ℕ) = 0 := le_antisymm hm bot_le,
rw this,
refine ⟨insert x s, self_mem_nhds_within, ftaylor_series_within 𝕜 f s, _⟩,
rw has_ftaylor_series_up_to_on_zero_iff,
exact ⟨by rwa insert_eq_of_mem hx, λ x hx, by simp [ftaylor_series_within]⟩
end
lemma times_cont_diff_within_at_zero (hx : x ∈ s) :
times_cont_diff_within_at 𝕜 0 f s x ↔ ∃ u ∈ 𝓝[s] x, continuous_on f (s ∩ u) :=
begin
split,
{ intros h,
obtain ⟨u, H, p, hp⟩ := h 0 (by norm_num),
refine ⟨u, _, _⟩,
{ simpa [hx] using H },
{ simp only [with_top.coe_zero, has_ftaylor_series_up_to_on_zero_iff] at hp,
exact hp.1.mono (inter_subset_right s u) } },
{ rintros ⟨u, H, hu⟩,
rw ← times_cont_diff_within_at_inter' H,
have h' : x ∈ s ∩ u := ⟨hx, mem_of_mem_nhds_within hx H⟩,
exact (times_cont_diff_on_zero.mpr hu).times_cont_diff_within_at h' }
end
/-- On a set with unique differentiability, any choice of iterated differential has to coincide
with the one we have chosen in `iterated_fderiv_within 𝕜 m f s`. -/
theorem has_ftaylor_series_up_to_on.eq_ftaylor_series_of_unique_diff_on {n : with_top ℕ}
(h : has_ftaylor_series_up_to_on n f p s)
{m : ℕ} (hmn : (m : with_top ℕ) ≤ n) (hs : unique_diff_on 𝕜 s) (hx : x ∈ s) :
p x m = iterated_fderiv_within 𝕜 m f s x :=
begin
induction m with m IH generalizing x,
{ rw [h.zero_eq' hx, iterated_fderiv_within_zero_eq_comp] },
{ have A : (m : with_top ℕ) < n := lt_of_lt_of_le (with_top.coe_lt_coe.2 (lt_add_one m)) hmn,
have : has_fderiv_within_at (λ (y : E), iterated_fderiv_within 𝕜 m f s y)
(continuous_multilinear_map.curry_left (p x (nat.succ m))) s x :=
(h.fderiv_within m A x hx).congr (λ y hy, (IH (le_of_lt A) hy).symm) (IH (le_of_lt A) hx).symm,
rw [iterated_fderiv_within_succ_eq_comp_left, function.comp_apply,
this.fderiv_within (hs x hx)],
exact (continuous_multilinear_map.uncurry_curry_left _).symm }
end
/-- When a function is `C^n` in a set `s` of unique differentiability, it admits
`ftaylor_series_within 𝕜 f s` as a Taylor series up to order `n` in `s`. -/
theorem times_cont_diff_on.ftaylor_series_within {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f s) (hs : unique_diff_on 𝕜 s) :
has_ftaylor_series_up_to_on n f (ftaylor_series_within 𝕜 f s) s :=
begin
split,
{ assume x hx,
simp only [ftaylor_series_within, continuous_multilinear_map.uncurry0_apply,
iterated_fderiv_within_zero_apply] },
{ assume m hm x hx,
rcases (h x hx) m.succ (with_top.add_one_le_of_lt hm) with ⟨u, hu, p, Hp⟩,
rw insert_eq_of_mem hx at hu,
rcases mem_nhds_within.1 hu with ⟨o, o_open, xo, ho⟩,
rw inter_comm at ho,
have : p x m.succ = ftaylor_series_within 𝕜 f s x m.succ,
{ change p x m.succ = iterated_fderiv_within 𝕜 m.succ f s x,
rw ← iterated_fderiv_within_inter (is_open.mem_nhds o_open xo) hs hx,
exact (Hp.mono ho).eq_ftaylor_series_of_unique_diff_on (le_refl _)
(hs.inter o_open) ⟨hx, xo⟩ },
rw [← this, ← has_fderiv_within_at_inter (is_open.mem_nhds o_open xo)],
have A : ∀ y ∈ s ∩ o, p y m = ftaylor_series_within 𝕜 f s y m,
{ rintros y ⟨hy, yo⟩,
change p y m = iterated_fderiv_within 𝕜 m f s y,
rw ← iterated_fderiv_within_inter (is_open.mem_nhds o_open yo) hs hy,
exact (Hp.mono ho).eq_ftaylor_series_of_unique_diff_on (with_top.coe_le_coe.2 (nat.le_succ m))
(hs.inter o_open) ⟨hy, yo⟩ },
exact ((Hp.mono ho).fderiv_within m (with_top.coe_lt_coe.2 (lt_add_one m)) x ⟨hx, xo⟩).congr
(λ y hy, (A y hy).symm) (A x ⟨hx, xo⟩).symm },
{ assume m hm,
apply continuous_on_of_locally_continuous_on,
assume x hx,
rcases h x hx m hm with ⟨u, hu, p, Hp⟩,
rcases mem_nhds_within.1 hu with ⟨o, o_open, xo, ho⟩,
rw insert_eq_of_mem hx at ho,
rw inter_comm at ho,
refine ⟨o, o_open, xo, _⟩,
have A : ∀ y ∈ s ∩ o, p y m = ftaylor_series_within 𝕜 f s y m,
{ rintros y ⟨hy, yo⟩,
change p y m = iterated_fderiv_within 𝕜 m f s y,
rw ← iterated_fderiv_within_inter (is_open.mem_nhds o_open yo) hs hy,
exact (Hp.mono ho).eq_ftaylor_series_of_unique_diff_on (le_refl _)
(hs.inter o_open) ⟨hy, yo⟩ },
exact ((Hp.mono ho).cont m (le_refl _)).congr (λ y hy, (A y hy).symm) }
end
lemma times_cont_diff_on_of_continuous_on_differentiable_on {n : with_top ℕ}
(Hcont : ∀ (m : ℕ), (m : with_top ℕ) ≤ n →
continuous_on (λ x, iterated_fderiv_within 𝕜 m f s x) s)
(Hdiff : ∀ (m : ℕ), (m : with_top ℕ) < n →
differentiable_on 𝕜 (λ x, iterated_fderiv_within 𝕜 m f s x) s) :
times_cont_diff_on 𝕜 n f s :=
begin
assume x hx m hm,
rw insert_eq_of_mem hx,
refine ⟨s, self_mem_nhds_within, ftaylor_series_within 𝕜 f s, _⟩,
split,
{ assume y hy,
simp only [ftaylor_series_within, continuous_multilinear_map.uncurry0_apply,
iterated_fderiv_within_zero_apply] },
{ assume k hk y hy,
convert (Hdiff k (lt_of_lt_of_le hk hm) y hy).has_fderiv_within_at,
simp only [ftaylor_series_within, iterated_fderiv_within_succ_eq_comp_left,
continuous_linear_equiv.coe_apply, function.comp_app, coe_fn_coe_base],
exact continuous_linear_map.curry_uncurry_left _ },
{ assume k hk,
exact Hcont k (le_trans hk hm) }
end
lemma times_cont_diff_on_of_differentiable_on {n : with_top ℕ}
(h : ∀(m : ℕ), (m : with_top ℕ) ≤ n → differentiable_on 𝕜 (iterated_fderiv_within 𝕜 m f s) s) :
times_cont_diff_on 𝕜 n f s :=
times_cont_diff_on_of_continuous_on_differentiable_on
(λ m hm, (h m hm).continuous_on) (λ m hm, (h m (le_of_lt hm)))
lemma times_cont_diff_on.continuous_on_iterated_fderiv_within {n : with_top ℕ} {m : ℕ}
(h : times_cont_diff_on 𝕜 n f s) (hmn : (m : with_top ℕ) ≤ n) (hs : unique_diff_on 𝕜 s) :
continuous_on (iterated_fderiv_within 𝕜 m f s) s :=
(h.ftaylor_series_within hs).cont m hmn
lemma times_cont_diff_on.differentiable_on_iterated_fderiv_within {n : with_top ℕ} {m : ℕ}
(h : times_cont_diff_on 𝕜 n f s) (hmn : (m : with_top ℕ) < n) (hs : unique_diff_on 𝕜 s) :
differentiable_on 𝕜 (iterated_fderiv_within 𝕜 m f s) s :=
λ x hx, ((h.ftaylor_series_within hs).fderiv_within m hmn x hx).differentiable_within_at
lemma times_cont_diff_on_iff_continuous_on_differentiable_on {n : with_top ℕ}
(hs : unique_diff_on 𝕜 s) :
times_cont_diff_on 𝕜 n f s ↔
(∀ (m : ℕ), (m : with_top ℕ) ≤ n →
continuous_on (λ x, iterated_fderiv_within 𝕜 m f s x) s)
∧ (∀ (m : ℕ), (m : with_top ℕ) < n →
differentiable_on 𝕜 (λ x, iterated_fderiv_within 𝕜 m f s x) s) :=
begin
split,
{ assume h,
split,
{ assume m hm, exact h.continuous_on_iterated_fderiv_within hm hs },
{ assume m hm, exact h.differentiable_on_iterated_fderiv_within hm hs } },
{ assume h,
exact times_cont_diff_on_of_continuous_on_differentiable_on h.1 h.2 }
end
/-- A function is `C^(n + 1)` on a domain with unique derivatives if and only if it is
differentiable there, and its derivative (expressed with `fderiv_within`) is `C^n`. -/
theorem times_cont_diff_on_succ_iff_fderiv_within {n : ℕ} (hs : unique_diff_on 𝕜 s) :
times_cont_diff_on 𝕜 ((n + 1) : ℕ) f s ↔
differentiable_on 𝕜 f s ∧ times_cont_diff_on 𝕜 n (λ y, fderiv_within 𝕜 f s y) s :=
begin
split,
{ assume H,
refine ⟨H.differentiable_on (with_top.coe_le_coe.2 (nat.le_add_left 1 n)), λ x hx, _⟩,
rcases times_cont_diff_within_at_succ_iff_has_fderiv_within_at.1 (H x hx)
with ⟨u, hu, f', hff', hf'⟩,
rcases mem_nhds_within.1 hu with ⟨o, o_open, xo, ho⟩,
rw [inter_comm, insert_eq_of_mem hx] at ho,
have := hf'.mono ho,
rw times_cont_diff_within_at_inter' (mem_nhds_within_of_mem_nhds (is_open.mem_nhds o_open xo))
at this,
apply this.congr_of_eventually_eq' _ hx,
have : o ∩ s ∈ 𝓝[s] x := mem_nhds_within.2 ⟨o, o_open, xo, subset.refl _⟩,
rw inter_comm at this,
apply filter.eventually_eq_of_mem this (λ y hy, _),
have A : fderiv_within 𝕜 f (s ∩ o) y = f' y :=
((hff' y (ho hy)).mono ho).fderiv_within (hs.inter o_open y hy),
rwa fderiv_within_inter (is_open.mem_nhds o_open hy.2) (hs y hy.1) at A, },
{ rintros ⟨hdiff, h⟩ x hx,
rw [times_cont_diff_within_at_succ_iff_has_fderiv_within_at, insert_eq_of_mem hx],
exact ⟨s, self_mem_nhds_within, fderiv_within 𝕜 f s,
λ y hy, (hdiff y hy).has_fderiv_within_at, h x hx⟩ }
end
/-- A function is `C^(n + 1)` on an open domain if and only if it is
differentiable there, and its derivative (expressed with `fderiv`) is `C^n`. -/
theorem times_cont_diff_on_succ_iff_fderiv_of_open {n : ℕ} (hs : is_open s) :
times_cont_diff_on 𝕜 ((n + 1) : ℕ) f s ↔
differentiable_on 𝕜 f s ∧ times_cont_diff_on 𝕜 n (λ y, fderiv 𝕜 f y) s :=
begin
rw times_cont_diff_on_succ_iff_fderiv_within hs.unique_diff_on,
congr' 2,
rw ← iff_iff_eq,
apply times_cont_diff_on_congr,
assume x hx,
exact fderiv_within_of_open hs hx
end
/-- A function is `C^∞` on a domain with unique derivatives if and only if it is differentiable
there, and its derivative (expressed with `fderiv_within`) is `C^∞`. -/
theorem times_cont_diff_on_top_iff_fderiv_within (hs : unique_diff_on 𝕜 s) :
times_cont_diff_on 𝕜 ∞ f s ↔
differentiable_on 𝕜 f s ∧ times_cont_diff_on 𝕜 ∞ (λ y, fderiv_within 𝕜 f s y) s :=
begin
split,
{ assume h,
refine ⟨h.differentiable_on le_top, _⟩,
apply times_cont_diff_on_top.2 (λ n, ((times_cont_diff_on_succ_iff_fderiv_within hs).1 _).2),
exact h.of_le le_top },
{ assume h,
refine times_cont_diff_on_top.2 (λ n, _),
have A : (n : with_top ℕ) ≤ ∞ := le_top,
apply ((times_cont_diff_on_succ_iff_fderiv_within hs).2 ⟨h.1, h.2.of_le A⟩).of_le,
exact with_top.coe_le_coe.2 (nat.le_succ n) }
end
/-- A function is `C^∞` on an open domain if and only if it is differentiable there, and its
derivative (expressed with `fderiv`) is `C^∞`. -/
theorem times_cont_diff_on_top_iff_fderiv_of_open (hs : is_open s) :
times_cont_diff_on 𝕜 ∞ f s ↔
differentiable_on 𝕜 f s ∧ times_cont_diff_on 𝕜 ∞ (λ y, fderiv 𝕜 f y) s :=
begin
rw times_cont_diff_on_top_iff_fderiv_within hs.unique_diff_on,
congr' 2,
rw ← iff_iff_eq,
apply times_cont_diff_on_congr,
assume x hx,
exact fderiv_within_of_open hs hx
end
lemma times_cont_diff_on.fderiv_within {m n : with_top ℕ}
(hf : times_cont_diff_on 𝕜 n f s) (hs : unique_diff_on 𝕜 s) (hmn : m + 1 ≤ n) :
times_cont_diff_on 𝕜 m (λ y, fderiv_within 𝕜 f s y) s :=
begin
cases m,
{ change ∞ + 1 ≤ n at hmn,
have : n = ∞, by simpa using hmn,
rw this at hf,
exact ((times_cont_diff_on_top_iff_fderiv_within hs).1 hf).2 },
{ change (m.succ : with_top ℕ) ≤ n at hmn,
exact ((times_cont_diff_on_succ_iff_fderiv_within hs).1 (hf.of_le hmn)).2 }
end
lemma times_cont_diff_on.fderiv_of_open {m n : with_top ℕ}
(hf : times_cont_diff_on 𝕜 n f s) (hs : is_open s) (hmn : m + 1 ≤ n) :
times_cont_diff_on 𝕜 m (λ y, fderiv 𝕜 f y) s :=
(hf.fderiv_within hs.unique_diff_on hmn).congr (λ x hx, (fderiv_within_of_open hs hx).symm)
lemma times_cont_diff_on.continuous_on_fderiv_within {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f s) (hs : unique_diff_on 𝕜 s) (hn : 1 ≤ n) :
continuous_on (λ x, fderiv_within 𝕜 f s x) s :=
((times_cont_diff_on_succ_iff_fderiv_within hs).1 (h.of_le hn)).2.continuous_on
lemma times_cont_diff_on.continuous_on_fderiv_of_open {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f s) (hs : is_open s) (hn : 1 ≤ n) :
continuous_on (λ x, fderiv 𝕜 f x) s :=
((times_cont_diff_on_succ_iff_fderiv_of_open hs).1 (h.of_le hn)).2.continuous_on
/-- If a function is at least `C^1`, its bundled derivative (mapping `(x, v)` to `Df(x) v`) is
continuous. -/
lemma times_cont_diff_on.continuous_on_fderiv_within_apply
{n : with_top ℕ} (h : times_cont_diff_on 𝕜 n f s) (hs : unique_diff_on 𝕜 s) (hn : 1 ≤ n) :
continuous_on (λp : E × E, (fderiv_within 𝕜 f s p.1 : E → F) p.2) (set.prod s univ) :=
begin
have A : continuous (λq : (E →L[𝕜] F) × E, q.1 q.2) := is_bounded_bilinear_map_apply.continuous,
have B : continuous_on (λp : E × E, (fderiv_within 𝕜 f s p.1, p.2)) (set.prod s univ),
{ apply continuous_on.prod _ continuous_snd.continuous_on,
exact continuous_on.comp (h.continuous_on_fderiv_within hs hn) continuous_fst.continuous_on
(prod_subset_preimage_fst _ _) },
exact A.comp_continuous_on B
end
/-! ### Functions with a Taylor series on the whole space -/
/-- `has_ftaylor_series_up_to n f p` registers the fact that `p 0 = f` and `p (m+1)` is a
derivative of `p m` for `m < n`, and is continuous for `m ≤ n`. This is a predicate analogous to
`has_fderiv_at` but for higher order derivatives. -/
structure has_ftaylor_series_up_to (n : with_top ℕ)
(f : E → F) (p : E → formal_multilinear_series 𝕜 E F) : Prop :=
(zero_eq : ∀ x, (p x 0).uncurry0 = f x)
(fderiv : ∀ (m : ℕ) (hm : (m : with_top ℕ) < n), ∀ x,
has_fderiv_at (λ y, p y m) (p x m.succ).curry_left x)
(cont : ∀ (m : ℕ) (hm : (m : with_top ℕ) ≤ n), continuous (λ x, p x m))
lemma has_ftaylor_series_up_to.zero_eq' {n : with_top ℕ}
(h : has_ftaylor_series_up_to n f p) (x : E) :
p x 0 = (continuous_multilinear_curry_fin0 𝕜 E F).symm (f x) :=
by { rw ← h.zero_eq x, symmetry, exact continuous_multilinear_map.uncurry0_curry0 _ }
lemma has_ftaylor_series_up_to_on_univ_iff {n : with_top ℕ} :
has_ftaylor_series_up_to_on n f p univ ↔ has_ftaylor_series_up_to n f p :=
begin
split,
{ assume H,
split,
{ exact λ x, H.zero_eq x (mem_univ x) },
{ assume m hm x,
rw ← has_fderiv_within_at_univ,
exact H.fderiv_within m hm x (mem_univ x) },
{ assume m hm,
rw continuous_iff_continuous_on_univ,
exact H.cont m hm } },
{ assume H,
split,
{ exact λ x hx, H.zero_eq x },
{ assume m hm x hx,
rw has_fderiv_within_at_univ,
exact H.fderiv m hm x },
{ assume m hm,
rw ← continuous_iff_continuous_on_univ,
exact H.cont m hm } }
end
lemma has_ftaylor_series_up_to.has_ftaylor_series_up_to_on {n : with_top ℕ}
(h : has_ftaylor_series_up_to n f p) (s : set E) :
has_ftaylor_series_up_to_on n f p s :=
(has_ftaylor_series_up_to_on_univ_iff.2 h).mono (subset_univ _)
lemma has_ftaylor_series_up_to.of_le {m n : with_top ℕ}
(h : has_ftaylor_series_up_to n f p) (hmn : m ≤ n) :
has_ftaylor_series_up_to m f p :=
by { rw ← has_ftaylor_series_up_to_on_univ_iff at h ⊢, exact h.of_le hmn }
lemma has_ftaylor_series_up_to.continuous {n : with_top ℕ}
(h : has_ftaylor_series_up_to n f p) : continuous f :=
begin
rw ← has_ftaylor_series_up_to_on_univ_iff at h,
rw continuous_iff_continuous_on_univ,
exact h.continuous_on
end
lemma has_ftaylor_series_up_to_zero_iff :
has_ftaylor_series_up_to 0 f p ↔ continuous f ∧ (∀ x, (p x 0).uncurry0 = f x) :=
by simp [has_ftaylor_series_up_to_on_univ_iff.symm, continuous_iff_continuous_on_univ,
has_ftaylor_series_up_to_on_zero_iff]
/-- If a function has a Taylor series at order at least `1`, then the term of order `1` of this
series is a derivative of `f`. -/
lemma has_ftaylor_series_up_to.has_fderiv_at {n : with_top ℕ}
(h : has_ftaylor_series_up_to n f p) (hn : 1 ≤ n) (x : E) :
has_fderiv_at f (continuous_multilinear_curry_fin1 𝕜 E F (p x 1)) x :=
begin
rw [← has_fderiv_within_at_univ],
exact (has_ftaylor_series_up_to_on_univ_iff.2 h).has_fderiv_within_at hn (mem_univ _)
end
lemma has_ftaylor_series_up_to.differentiable {n : with_top ℕ}
(h : has_ftaylor_series_up_to n f p) (hn : 1 ≤ n) : differentiable 𝕜 f :=
λ x, (h.has_fderiv_at hn x).differentiable_at
/-- `p` is a Taylor series of `f` up to `n+1` if and only if `p.shift` is a Taylor series up to `n`
for `p 1`, which is a derivative of `f`. -/
theorem has_ftaylor_series_up_to_succ_iff_right {n : ℕ} :
has_ftaylor_series_up_to ((n + 1) : ℕ) f p ↔
(∀ x, (p x 0).uncurry0 = f x)
∧ (∀ x, has_fderiv_at (λ y, p y 0) (p x 1).curry_left x)
∧ has_ftaylor_series_up_to n
(λ x, continuous_multilinear_curry_fin1 𝕜 E F (p x 1)) (λ x, (p x).shift) :=
by simp [has_ftaylor_series_up_to_on_succ_iff_right, has_ftaylor_series_up_to_on_univ_iff.symm,
-add_comm, -with_zero.coe_add]
/-! ### Smooth functions at a point -/
variable (𝕜)
/-- A function is continuously differentiable up to `n` at a point `x` if, for any integer `k ≤ n`,
there is a neighborhood of `x` where `f` admits derivatives up to order `n`, which are continuous.
-/
def times_cont_diff_at (n : with_top ℕ) (f : E → F) (x : E) :=
times_cont_diff_within_at 𝕜 n f univ x
variable {𝕜}
theorem times_cont_diff_within_at_univ {n : with_top ℕ} :
times_cont_diff_within_at 𝕜 n f univ x ↔ times_cont_diff_at 𝕜 n f x :=
iff.rfl
lemma times_cont_diff_at_top :
times_cont_diff_at 𝕜 ∞ f x ↔ ∀ (n : ℕ), times_cont_diff_at 𝕜 n f x :=
by simp [← times_cont_diff_within_at_univ, times_cont_diff_within_at_top]
lemma times_cont_diff_at.times_cont_diff_within_at {n : with_top ℕ}
(h : times_cont_diff_at 𝕜 n f x) : times_cont_diff_within_at 𝕜 n f s x :=
h.mono (subset_univ _)
lemma times_cont_diff_within_at.times_cont_diff_at {n : with_top ℕ}
(h : times_cont_diff_within_at 𝕜 n f s x) (hx : s ∈ 𝓝 x) :
times_cont_diff_at 𝕜 n f x :=
by rwa [times_cont_diff_at, ← times_cont_diff_within_at_inter hx, univ_inter]
lemma times_cont_diff_at.congr_of_eventually_eq {n : with_top ℕ}
(h : times_cont_diff_at 𝕜 n f x) (hg : f₁ =ᶠ[𝓝 x] f) :
times_cont_diff_at 𝕜 n f₁ x :=
h.congr_of_eventually_eq' (by rwa nhds_within_univ) (mem_univ x)
lemma times_cont_diff_at.of_le {m n : with_top ℕ}
(h : times_cont_diff_at 𝕜 n f x) (hmn : m ≤ n) :
times_cont_diff_at 𝕜 m f x :=
h.of_le hmn
lemma times_cont_diff_at.continuous_at {n : with_top ℕ}
(h : times_cont_diff_at 𝕜 n f x) : continuous_at f x :=
by simpa [continuous_within_at_univ] using h.continuous_within_at
/-- If a function is `C^n` with `n ≥ 1` at a point, then it is differentiable there. -/
lemma times_cont_diff_at.differentiable_at {n : with_top ℕ}
(h : times_cont_diff_at 𝕜 n f x) (hn : 1 ≤ n) : differentiable_at 𝕜 f x :=
by simpa [hn, differentiable_within_at_univ] using h.differentiable_within_at
/-- A function is `C^(n + 1)` at a point iff locally, it has a derivative which is `C^n`. -/
theorem times_cont_diff_at_succ_iff_has_fderiv_at {n : ℕ} :
times_cont_diff_at 𝕜 ((n + 1) : ℕ) f x
↔ (∃ f' : E → (E →L[𝕜] F), (∃ u ∈ 𝓝 x, (∀ x ∈ u, has_fderiv_at f (f' x) x))
∧ (times_cont_diff_at 𝕜 n f' x)) :=
begin
rw [← times_cont_diff_within_at_univ, times_cont_diff_within_at_succ_iff_has_fderiv_within_at],
simp only [nhds_within_univ, exists_prop, mem_univ, insert_eq_of_mem],
split,
{ rintros ⟨u, H, f', h_fderiv, h_times_cont_diff⟩,
rcases mem_nhds_iff.mp H with ⟨t, htu, ht, hxt⟩,
refine ⟨f', ⟨t, _⟩, h_times_cont_diff.times_cont_diff_at H⟩,
refine ⟨mem_nhds_iff.mpr ⟨t, subset.rfl, ht, hxt⟩, _⟩,
intros y hyt,
refine (h_fderiv y (htu hyt)).has_fderiv_at _,
exact mem_nhds_iff.mpr ⟨t, htu, ht, hyt⟩ },
{ rintros ⟨f', ⟨u, H, h_fderiv⟩, h_times_cont_diff⟩,
refine ⟨u, H, f', _, h_times_cont_diff.times_cont_diff_within_at⟩,
intros x hxu,
exact (h_fderiv x hxu).has_fderiv_within_at }
end
/-! ### Smooth functions -/
variable (𝕜)
/-- A function is continuously differentiable up to `n` if it admits derivatives up to
order `n`, which are continuous. Contrary to the case of definitions in domains (where derivatives
might not be unique) we do not need to localize the definition in space or time.
-/
definition times_cont_diff (n : with_top ℕ) (f : E → F) :=
∃ p : E → formal_multilinear_series 𝕜 E F, has_ftaylor_series_up_to n f p
variable {𝕜}
theorem times_cont_diff_on_univ {n : with_top ℕ} :
times_cont_diff_on 𝕜 n f univ ↔ times_cont_diff 𝕜 n f :=
begin
split,
{ assume H,
use ftaylor_series_within 𝕜 f univ,
rw ← has_ftaylor_series_up_to_on_univ_iff,
exact H.ftaylor_series_within unique_diff_on_univ },
{ rintros ⟨p, hp⟩ x hx m hm,
exact ⟨univ, filter.univ_sets _, p, (hp.has_ftaylor_series_up_to_on univ).of_le hm⟩ }
end
lemma times_cont_diff_iff_times_cont_diff_at {n : with_top ℕ} :
times_cont_diff 𝕜 n f ↔ ∀ x, times_cont_diff_at 𝕜 n f x :=
by simp [← times_cont_diff_on_univ, times_cont_diff_on, times_cont_diff_at]
lemma times_cont_diff.times_cont_diff_at {n : with_top ℕ} (h : times_cont_diff 𝕜 n f) :
times_cont_diff_at 𝕜 n f x :=
times_cont_diff_iff_times_cont_diff_at.1 h x
lemma times_cont_diff.times_cont_diff_within_at {n : with_top ℕ} (h : times_cont_diff 𝕜 n f) :
times_cont_diff_within_at 𝕜 n f s x :=
h.times_cont_diff_at.times_cont_diff_within_at
lemma times_cont_diff_top :
times_cont_diff 𝕜 ∞ f ↔ ∀ (n : ℕ), times_cont_diff 𝕜 n f :=
by simp [times_cont_diff_on_univ.symm, times_cont_diff_on_top]
lemma times_cont_diff_all_iff_nat :
(∀ n, times_cont_diff 𝕜 n f) ↔ (∀ n : ℕ, times_cont_diff 𝕜 n f) :=
by simp only [← times_cont_diff_on_univ, times_cont_diff_on_all_iff_nat]
lemma times_cont_diff.times_cont_diff_on {n : with_top ℕ}
(h : times_cont_diff 𝕜 n f) : times_cont_diff_on 𝕜 n f s :=
(times_cont_diff_on_univ.2 h).mono (subset_univ _)
@[simp] lemma times_cont_diff_zero :
times_cont_diff 𝕜 0 f ↔ continuous f :=
begin
rw [← times_cont_diff_on_univ, continuous_iff_continuous_on_univ],
exact times_cont_diff_on_zero
end
lemma times_cont_diff_at_zero :
times_cont_diff_at 𝕜 0 f x ↔ ∃ u ∈ 𝓝 x, continuous_on f u :=
by { rw ← times_cont_diff_within_at_univ, simp [times_cont_diff_within_at_zero, nhds_within_univ] }
lemma times_cont_diff.of_le {m n : with_top ℕ}
(h : times_cont_diff 𝕜 n f) (hmn : m ≤ n) :
times_cont_diff 𝕜 m f :=
times_cont_diff_on_univ.1 $ (times_cont_diff_on_univ.2 h).of_le hmn
lemma times_cont_diff.continuous {n : with_top ℕ}
(h : times_cont_diff 𝕜 n f) : continuous f :=
times_cont_diff_zero.1 (h.of_le bot_le)
/-- If a function is `C^n` with `n ≥ 1`, then it is differentiable. -/
lemma times_cont_diff.differentiable {n : with_top ℕ}
(h : times_cont_diff 𝕜 n f) (hn : 1 ≤ n) : differentiable 𝕜 f :=
differentiable_on_univ.1 $ (times_cont_diff_on_univ.2 h).differentiable_on hn
/-! ### Iterated derivative -/
variable (𝕜)
/-- The `n`-th derivative of a function, as a multilinear map, defined inductively. -/
noncomputable def iterated_fderiv (n : ℕ) (f : E → F) :
E → (E [×n]→L[𝕜] F) :=
nat.rec_on n
(λ x, continuous_multilinear_map.curry0 𝕜 E (f x))
(λ n rec x, continuous_linear_map.uncurry_left (fderiv 𝕜 rec x))
/-- Formal Taylor series associated to a function within a set. -/
def ftaylor_series (f : E → F) (x : E) : formal_multilinear_series 𝕜 E F :=
λ n, iterated_fderiv 𝕜 n f x
variable {𝕜}
@[simp] lemma iterated_fderiv_zero_apply (m : (fin 0) → E) :
(iterated_fderiv 𝕜 0 f x : ((fin 0) → E) → F) m = f x := rfl
lemma iterated_fderiv_zero_eq_comp :
iterated_fderiv 𝕜 0 f = (continuous_multilinear_curry_fin0 𝕜 E F).symm ∘ f := rfl
lemma iterated_fderiv_succ_apply_left {n : ℕ} (m : fin (n + 1) → E):
(iterated_fderiv 𝕜 (n + 1) f x : (fin (n + 1) → E) → F) m
= (fderiv 𝕜 (iterated_fderiv 𝕜 n f) x : E → (E [×n]→L[𝕜] F)) (m 0) (tail m) := rfl
/-- Writing explicitly the `n+1`-th derivative as the composition of a currying linear equiv,
and the derivative of the `n`-th derivative. -/
lemma iterated_fderiv_succ_eq_comp_left {n : ℕ} :
iterated_fderiv 𝕜 (n + 1) f =
(continuous_multilinear_curry_left_equiv 𝕜 (λ(i : fin (n + 1)), E) F)
∘ (fderiv 𝕜 (iterated_fderiv 𝕜 n f)) := rfl
lemma iterated_fderiv_within_univ {n : ℕ} :
iterated_fderiv_within 𝕜 n f univ = iterated_fderiv 𝕜 n f :=
begin
induction n with n IH,
{ ext x, simp },
{ ext x m,
rw [iterated_fderiv_succ_apply_left, iterated_fderiv_within_succ_apply_left, IH,
fderiv_within_univ] }
end
lemma ftaylor_series_within_univ :
ftaylor_series_within 𝕜 f univ = ftaylor_series 𝕜 f :=
begin
ext1 x, ext1 n,
change iterated_fderiv_within 𝕜 n f univ x = iterated_fderiv 𝕜 n f x,
rw iterated_fderiv_within_univ
end
theorem iterated_fderiv_succ_apply_right {n : ℕ} (m : fin (n + 1) → E) :
(iterated_fderiv 𝕜 (n + 1) f x : (fin (n + 1) → E) → F) m
= iterated_fderiv 𝕜 n (λy, fderiv 𝕜 f y) x (init m) (m (last n)) :=
begin
rw [← iterated_fderiv_within_univ, ← iterated_fderiv_within_univ, ← fderiv_within_univ],
exact iterated_fderiv_within_succ_apply_right unique_diff_on_univ (mem_univ _) _
end
/-- Writing explicitly the `n+1`-th derivative as the composition of a currying linear equiv,
and the `n`-th derivative of the derivative. -/
lemma iterated_fderiv_succ_eq_comp_right {n : ℕ} :
iterated_fderiv 𝕜 (n + 1) f x =
((continuous_multilinear_curry_right_equiv' 𝕜 n E F)
∘ (iterated_fderiv 𝕜 n (λy, fderiv 𝕜 f y))) x :=
by { ext m, rw iterated_fderiv_succ_apply_right, refl }
@[simp] lemma iterated_fderiv_one_apply (m : (fin 1) → E) :
(iterated_fderiv 𝕜 1 f x : ((fin 1) → E) → F) m
= (fderiv 𝕜 f x : E → F) (m 0) :=
by { rw [iterated_fderiv_succ_apply_right, iterated_fderiv_zero_apply], refl }
/-- When a function is `C^n` in a set `s` of unique differentiability, it admits
`ftaylor_series_within 𝕜 f s` as a Taylor series up to order `n` in `s`. -/
theorem times_cont_diff_on_iff_ftaylor_series {n : with_top ℕ} :
times_cont_diff 𝕜 n f ↔ has_ftaylor_series_up_to n f (ftaylor_series 𝕜 f) :=
begin
split,
{ rw [← times_cont_diff_on_univ, ← has_ftaylor_series_up_to_on_univ_iff,
← ftaylor_series_within_univ],
exact λ h, times_cont_diff_on.ftaylor_series_within h unique_diff_on_univ },
{ assume h, exact ⟨ftaylor_series 𝕜 f, h⟩ }
end
lemma times_cont_diff_iff_continuous_differentiable {n : with_top ℕ} :
times_cont_diff 𝕜 n f ↔
(∀ (m : ℕ), (m : with_top ℕ) ≤ n → continuous (λ x, iterated_fderiv 𝕜 m f x))
∧ (∀ (m : ℕ), (m : with_top ℕ) < n → differentiable 𝕜 (λ x, iterated_fderiv 𝕜 m f x)) :=
by simp [times_cont_diff_on_univ.symm, continuous_iff_continuous_on_univ,
differentiable_on_univ.symm, iterated_fderiv_within_univ,
times_cont_diff_on_iff_continuous_on_differentiable_on unique_diff_on_univ]
lemma times_cont_diff_of_differentiable_iterated_fderiv {n : with_top ℕ}
(h : ∀(m : ℕ), (m : with_top ℕ) ≤ n → differentiable 𝕜 (iterated_fderiv 𝕜 m f)) :
times_cont_diff 𝕜 n f :=
times_cont_diff_iff_continuous_differentiable.2
⟨λ m hm, (h m hm).continuous, λ m hm, (h m (le_of_lt hm))⟩
/-- A function is `C^(n + 1)` on a domain with unique derivatives if and only if
it is differentiable there, and its derivative is `C^n`. -/
theorem times_cont_diff_succ_iff_fderiv {n : ℕ} :
times_cont_diff 𝕜 ((n + 1) : ℕ) f ↔
differentiable 𝕜 f ∧ times_cont_diff 𝕜 n (λ y, fderiv 𝕜 f y) :=
by simp [times_cont_diff_on_univ.symm, differentiable_on_univ.symm, fderiv_within_univ.symm,
- fderiv_within_univ, times_cont_diff_on_succ_iff_fderiv_within unique_diff_on_univ,
-with_zero.coe_add, -add_comm]
/-- A function is `C^∞` on a domain with unique derivatives if and only if it is differentiable
there, and its derivative is `C^∞`. -/
theorem times_cont_diff_top_iff_fderiv :
times_cont_diff 𝕜 ∞ f ↔
differentiable 𝕜 f ∧ times_cont_diff 𝕜 ∞ (λ y, fderiv 𝕜 f y) :=
begin
simp [times_cont_diff_on_univ.symm, differentiable_on_univ.symm, fderiv_within_univ.symm,
- fderiv_within_univ],
rw times_cont_diff_on_top_iff_fderiv_within unique_diff_on_univ,
end
lemma times_cont_diff.continuous_fderiv {n : with_top ℕ}
(h : times_cont_diff 𝕜 n f) (hn : 1 ≤ n) :
continuous (λ x, fderiv 𝕜 f x) :=
((times_cont_diff_succ_iff_fderiv).1 (h.of_le hn)).2.continuous
/-- If a function is at least `C^1`, its bundled derivative (mapping `(x, v)` to `Df(x) v`) is
continuous. -/
lemma times_cont_diff.continuous_fderiv_apply {n : with_top ℕ}
(h : times_cont_diff 𝕜 n f) (hn : 1 ≤ n) :
continuous (λp : E × E, (fderiv 𝕜 f p.1 : E → F) p.2) :=
begin
have A : continuous (λq : (E →L[𝕜] F) × E, q.1 q.2) := is_bounded_bilinear_map_apply.continuous,
have B : continuous (λp : E × E, (fderiv 𝕜 f p.1, p.2)),
{ apply continuous.prod_mk _ continuous_snd,
exact continuous.comp (h.continuous_fderiv hn) continuous_fst },
exact A.comp B
end
/-! ### Constants -/
lemma iterated_fderiv_within_zero_fun {n : ℕ} :
iterated_fderiv 𝕜 n (λ x : E, (0 : F)) = 0 :=
begin
induction n with n IH,
{ ext m, simp },
{ ext x m,
rw [iterated_fderiv_succ_apply_left, IH],
change (fderiv 𝕜 (λ (x : E), (0 : (E [×n]→L[𝕜] F))) x : E → (E [×n]→L[𝕜] F)) (m 0) (tail m) = _,
rw fderiv_const,
refl }
end
lemma times_cont_diff_zero_fun {n : with_top ℕ} :
times_cont_diff 𝕜 n (λ x : E, (0 : F)) :=
begin
apply times_cont_diff_of_differentiable_iterated_fderiv (λm hm, _),
rw iterated_fderiv_within_zero_fun,
apply differentiable_const (0 : (E [×m]→L[𝕜] F))
end
/--
Constants are `C^∞`.
-/
lemma times_cont_diff_const {n : with_top ℕ} {c : F} : times_cont_diff 𝕜 n (λx : E, c) :=
begin
suffices h : times_cont_diff 𝕜 ∞ (λx : E, c), by exact h.of_le le_top,
rw times_cont_diff_top_iff_fderiv,
refine ⟨differentiable_const c, _⟩,
rw fderiv_const,
exact times_cont_diff_zero_fun
end
lemma times_cont_diff_on_const {n : with_top ℕ} {c : F} {s : set E} :
times_cont_diff_on 𝕜 n (λx : E, c) s :=
times_cont_diff_const.times_cont_diff_on
lemma times_cont_diff_at_const {n : with_top ℕ} {c : F} :
times_cont_diff_at 𝕜 n (λx : E, c) x :=
times_cont_diff_const.times_cont_diff_at
lemma times_cont_diff_within_at_const {n : with_top ℕ} {c : F} :
times_cont_diff_within_at 𝕜 n (λx : E, c) s x :=
times_cont_diff_at_const.times_cont_diff_within_at
@[nontriviality] lemma times_cont_diff_of_subsingleton [subsingleton F] {n : with_top ℕ} :
times_cont_diff 𝕜 n f :=
by { rw [subsingleton.elim f (λ _, 0)], exact times_cont_diff_const }
@[nontriviality] lemma times_cont_diff_at_of_subsingleton [subsingleton F] {n : with_top ℕ} :
times_cont_diff_at 𝕜 n f x :=
by { rw [subsingleton.elim f (λ _, 0)], exact times_cont_diff_at_const }
@[nontriviality] lemma times_cont_diff_within_at_of_subsingleton [subsingleton F] {n : with_top ℕ} :
times_cont_diff_within_at 𝕜 n f s x :=
by { rw [subsingleton.elim f (λ _, 0)], exact times_cont_diff_within_at_const }
@[nontriviality] lemma times_cont_diff_on_of_subsingleton [subsingleton F] {n : with_top ℕ} :
times_cont_diff_on 𝕜 n f s :=
by { rw [subsingleton.elim f (λ _, 0)], exact times_cont_diff_on_const }
/-! ### Linear functions -/
/--
Unbundled bounded linear functions are `C^∞`.
-/
lemma is_bounded_linear_map.times_cont_diff {n : with_top ℕ} (hf : is_bounded_linear_map 𝕜 f) :
times_cont_diff 𝕜 n f :=
begin
suffices h : times_cont_diff 𝕜 ∞ f, by exact h.of_le le_top,
rw times_cont_diff_top_iff_fderiv,
refine ⟨hf.differentiable, _⟩,
simp [hf.fderiv],
exact times_cont_diff_const
end
lemma continuous_linear_map.times_cont_diff {n : with_top ℕ} (f : E →L[𝕜] F) :
times_cont_diff 𝕜 n f :=
f.is_bounded_linear_map.times_cont_diff
lemma continuous_linear_equiv.times_cont_diff {n : with_top ℕ} (f : E ≃L[𝕜] F) :
times_cont_diff 𝕜 n f :=
(f : E →L[𝕜] F).times_cont_diff
lemma linear_isometry_map.times_cont_diff {n : with_top ℕ} (f : E →ₗᵢ[𝕜] F) :
times_cont_diff 𝕜 n f :=
f.to_continuous_linear_map.times_cont_diff
lemma linear_isometry_equiv.times_cont_diff {n : with_top ℕ} (f : E ≃ₗᵢ[𝕜] F) :
times_cont_diff 𝕜 n f :=
(f : E →L[𝕜] F).times_cont_diff
/--
The first projection in a product is `C^∞`.
-/
lemma times_cont_diff_fst {n : with_top ℕ} : times_cont_diff 𝕜 n (prod.fst : E × F → E) :=
is_bounded_linear_map.times_cont_diff is_bounded_linear_map.fst
/--
The first projection on a domain in a product is `C^∞`.
-/
lemma times_cont_diff_on_fst {s : set (E×F)} {n : with_top ℕ} :
times_cont_diff_on 𝕜 n (prod.fst : E × F → E) s :=
times_cont_diff.times_cont_diff_on times_cont_diff_fst
/--
The first projection at a point in a product is `C^∞`.
-/
lemma times_cont_diff_at_fst {p : E × F} {n : with_top ℕ} :
times_cont_diff_at 𝕜 n (prod.fst : E × F → E) p :=
times_cont_diff_fst.times_cont_diff_at
/--
The first projection within a domain at a point in a product is `C^∞`.
-/
lemma times_cont_diff_within_at_fst {s : set (E × F)} {p : E × F} {n : with_top ℕ} :
times_cont_diff_within_at 𝕜 n (prod.fst : E × F → E) s p :=
times_cont_diff_fst.times_cont_diff_within_at
/--
The second projection in a product is `C^∞`.
-/
lemma times_cont_diff_snd {n : with_top ℕ} : times_cont_diff 𝕜 n (prod.snd : E × F → F) :=
is_bounded_linear_map.times_cont_diff is_bounded_linear_map.snd
/--
The second projection on a domain in a product is `C^∞`.
-/
lemma times_cont_diff_on_snd {s : set (E×F)} {n : with_top ℕ} :
times_cont_diff_on 𝕜 n (prod.snd : E × F → F) s :=
times_cont_diff.times_cont_diff_on times_cont_diff_snd
/--
The second projection at a point in a product is `C^∞`.
-/
lemma times_cont_diff_at_snd {p : E × F} {n : with_top ℕ} :
times_cont_diff_at 𝕜 n (prod.snd : E × F → F) p :=
times_cont_diff_snd.times_cont_diff_at
/--
The second projection within a domain at a point in a product is `C^∞`.
-/
lemma times_cont_diff_within_at_snd {s : set (E × F)} {p : E × F} {n : with_top ℕ} :
times_cont_diff_within_at 𝕜 n (prod.snd : E × F → F) s p :=
times_cont_diff_snd.times_cont_diff_within_at
/--
The identity is `C^∞`.
-/
lemma times_cont_diff_id {n : with_top ℕ} : times_cont_diff 𝕜 n (id : E → E) :=
is_bounded_linear_map.id.times_cont_diff
lemma times_cont_diff_within_at_id {n : with_top ℕ} {s x} :
times_cont_diff_within_at 𝕜 n (id : E → E) s x :=
times_cont_diff_id.times_cont_diff_within_at
lemma times_cont_diff_at_id {n : with_top ℕ} {x} :
times_cont_diff_at 𝕜 n (id : E → E) x :=
times_cont_diff_id.times_cont_diff_at
lemma times_cont_diff_on_id {n : with_top ℕ} {s} :
times_cont_diff_on 𝕜 n (id : E → E) s :=
times_cont_diff_id.times_cont_diff_on
/--
Bilinear functions are `C^∞`.
-/
lemma is_bounded_bilinear_map.times_cont_diff {n : with_top ℕ} (hb : is_bounded_bilinear_map 𝕜 b) :
times_cont_diff 𝕜 n b :=
begin
suffices h : times_cont_diff 𝕜 ∞ b, by exact h.of_le le_top,
rw times_cont_diff_top_iff_fderiv,
refine ⟨hb.differentiable, _⟩,
simp [hb.fderiv],
exact hb.is_bounded_linear_map_deriv.times_cont_diff
end
/-- If `f` admits a Taylor series `p` in a set `s`, and `g` is linear, then `g ∘ f` admits a Taylor
series whose `k`-th term is given by `g ∘ (p k)`. -/
lemma has_ftaylor_series_up_to_on.continuous_linear_map_comp {n : with_top ℕ} (g : F →L[𝕜] G)
(hf : has_ftaylor_series_up_to_on n f p s) :
has_ftaylor_series_up_to_on n (g ∘ f) (λ x k, g.comp_continuous_multilinear_map (p x k)) s :=
begin
set L : Π m : ℕ, (E [×m]→L[𝕜] F) →L[𝕜] (E [×m]→L[𝕜] G) :=
λ m, continuous_linear_map.comp_continuous_multilinear_mapL g,
split,
{ exact λ x hx, congr_arg g (hf.zero_eq x hx) },
{ intros m hm x hx,
convert (L m).has_fderiv_at.comp_has_fderiv_within_at x (hf.fderiv_within m hm x hx) },
{ intros m hm,
convert (L m).continuous.comp_continuous_on (hf.cont m hm) }
end
/-- Composition by continuous linear maps on the left preserves `C^n` functions in a domain
at a point. -/
lemma times_cont_diff_within_at.continuous_linear_map_comp {n : with_top ℕ} (g : F →L[𝕜] G)
(hf : times_cont_diff_within_at 𝕜 n f s x) :
times_cont_diff_within_at 𝕜 n (g ∘ f) s x :=
begin
assume m hm,
rcases hf m hm with ⟨u, hu, p, hp⟩,
exact ⟨u, hu, _, hp.continuous_linear_map_comp g⟩,
end
/-- Composition by continuous linear maps on the left preserves `C^n` functions in a domain
at a point. -/
lemma times_cont_diff_at.continuous_linear_map_comp {n : with_top ℕ} (g : F →L[𝕜] G)
(hf : times_cont_diff_at 𝕜 n f x) :
times_cont_diff_at 𝕜 n (g ∘ f) x :=
times_cont_diff_within_at.continuous_linear_map_comp g hf
/-- Composition by continuous linear maps on the left preserves `C^n` functions on domains. -/
lemma times_cont_diff_on.continuous_linear_map_comp {n : with_top ℕ} (g : F →L[𝕜] G)
(hf : times_cont_diff_on 𝕜 n f s) :
times_cont_diff_on 𝕜 n (g ∘ f) s :=
λ x hx, (hf x hx).continuous_linear_map_comp g
/-- Composition by continuous linear maps on the left preserves `C^n` functions. -/
lemma times_cont_diff.continuous_linear_map_comp {n : with_top ℕ} {f : E → F} (g : F →L[𝕜] G)
(hf : times_cont_diff 𝕜 n f) : times_cont_diff 𝕜 n (λx, g (f x)) :=
times_cont_diff_on_univ.1 $ times_cont_diff_on.continuous_linear_map_comp
_ (times_cont_diff_on_univ.2 hf)
/-- Composition by continuous linear equivs on the left respects higher differentiability on
domains. -/
lemma continuous_linear_equiv.comp_times_cont_diff_within_at_iff
{n : with_top ℕ} (e : F ≃L[𝕜] G) :
times_cont_diff_within_at 𝕜 n (e ∘ f) s x ↔ times_cont_diff_within_at 𝕜 n f s x :=
begin
split,
{ assume H,
have : f = e.symm ∘ (e ∘ f),
by { ext y, simp only [function.comp_app], rw e.symm_apply_apply (f y) },
rw this,
exact H.continuous_linear_map_comp _ },
{ assume H,
exact H.continuous_linear_map_comp _ }
end
/-- Composition by continuous linear equivs on the left respects higher differentiability on
domains. -/
lemma continuous_linear_equiv.comp_times_cont_diff_on_iff
{n : with_top ℕ} (e : F ≃L[𝕜] G) :
times_cont_diff_on 𝕜 n (e ∘ f) s ↔ times_cont_diff_on 𝕜 n f s :=
by simp [times_cont_diff_on, e.comp_times_cont_diff_within_at_iff]
/-- If `f` admits a Taylor series `p` in a set `s`, and `g` is linear, then `f ∘ g` admits a Taylor
series in `g ⁻¹' s`, whose `k`-th term is given by `p k (g v₁, ..., g vₖ)` . -/
lemma has_ftaylor_series_up_to_on.comp_continuous_linear_map {n : with_top ℕ}
(hf : has_ftaylor_series_up_to_on n f p s) (g : G →L[𝕜] E) :
has_ftaylor_series_up_to_on n (f ∘ g)
(λ x k, (p (g x) k).comp_continuous_linear_map (λ _, g)) (g ⁻¹' s) :=
begin
let A : Π m : ℕ, (E [×m]→L[𝕜] F) → (G [×m]→L[𝕜] F) :=
λ m h, h.comp_continuous_linear_map (λ _, g),
have hA : ∀ m, is_bounded_linear_map 𝕜 (A m) :=
λ m, is_bounded_linear_map_continuous_multilinear_map_comp_linear g,
split,
{ assume x hx,
simp only [(hf.zero_eq (g x) hx).symm, function.comp_app],
change p (g x) 0 (λ (i : fin 0), g 0) = p (g x) 0 0,
rw continuous_linear_map.map_zero,
refl },
{ assume m hm x hx,
convert ((hA m).has_fderiv_at).comp_has_fderiv_within_at x
((hf.fderiv_within m hm (g x) hx).comp x (g.has_fderiv_within_at) (subset.refl _)),
ext y v,
change p (g x) (nat.succ m) (g ∘ (cons y v)) = p (g x) m.succ (cons (g y) (g ∘ v)),
rw comp_cons },
{ assume m hm,
exact (hA m).continuous.comp_continuous_on
((hf.cont m hm).comp g.continuous.continuous_on (subset.refl _)) }
end
/-- Composition by continuous linear maps on the right preserves `C^n` functions at a point on
a domain. -/
lemma times_cont_diff_within_at.comp_continuous_linear_map {n : with_top ℕ} {x : G}
(g : G →L[𝕜] E) (hf : times_cont_diff_within_at 𝕜 n f s (g x)) :
times_cont_diff_within_at 𝕜 n (f ∘ g) (g ⁻¹' s) x :=
begin
assume m hm,
rcases hf m hm with ⟨u, hu, p, hp⟩,
refine ⟨g ⁻¹' u, _, _, hp.comp_continuous_linear_map g⟩,
apply continuous_within_at.preimage_mem_nhds_within',
{ exact g.continuous.continuous_within_at },
{ apply nhds_within_mono (g x) _ hu,
rw image_insert_eq,
exact insert_subset_insert (image_preimage_subset g s) }
end
/-- Composition by continuous linear maps on the right preserves `C^n` functions on domains. -/
lemma times_cont_diff_on.comp_continuous_linear_map {n : with_top ℕ}
(hf : times_cont_diff_on 𝕜 n f s) (g : G →L[𝕜] E) :
times_cont_diff_on 𝕜 n (f ∘ g) (g ⁻¹' s) :=
λ x hx, (hf (g x) hx).comp_continuous_linear_map g
/-- Composition by continuous linear maps on the right preserves `C^n` functions. -/
lemma times_cont_diff.comp_continuous_linear_map {n : with_top ℕ} {f : E → F} {g : G →L[𝕜] E}
(hf : times_cont_diff 𝕜 n f) : times_cont_diff 𝕜 n (f ∘ g) :=
times_cont_diff_on_univ.1 $
times_cont_diff_on.comp_continuous_linear_map (times_cont_diff_on_univ.2 hf) _
/-- Composition by continuous linear equivs on the right respects higher differentiability at a
point in a domain. -/
lemma continuous_linear_equiv.times_cont_diff_within_at_comp_iff {n : with_top ℕ} (e : G ≃L[𝕜] E) :
times_cont_diff_within_at 𝕜 n (f ∘ e) (e ⁻¹' s) (e.symm x) ↔
times_cont_diff_within_at 𝕜 n f s x :=
begin
split,
{ assume H,
have A : f = (f ∘ e) ∘ e.symm,
by { ext y, simp only [function.comp_app], rw e.apply_symm_apply y },
have B : e.symm ⁻¹' (e ⁻¹' s) = s,
by { rw [← preimage_comp, e.self_comp_symm], refl },
rw [A, ← B],
exact H.comp_continuous_linear_map _},
{ assume H,
have : x = e (e.symm x), by simp,
rw this at H,
exact H.comp_continuous_linear_map _ },
end
/-- Composition by continuous linear equivs on the right respects higher differentiability on
domains. -/
lemma continuous_linear_equiv.times_cont_diff_on_comp_iff {n : with_top ℕ} (e : G ≃L[𝕜] E) :
times_cont_diff_on 𝕜 n (f ∘ e) (e ⁻¹' s) ↔ times_cont_diff_on 𝕜 n f s :=
begin
refine ⟨λ H, _, λ H, H.comp_continuous_linear_map _⟩,
have A : f = (f ∘ e) ∘ e.symm,
by { ext y, simp only [function.comp_app], rw e.apply_symm_apply y },
have B : e.symm ⁻¹' (e ⁻¹' s) = s,
by { rw [← preimage_comp, e.self_comp_symm], refl },
rw [A, ← B],
exact H.comp_continuous_linear_map _
end
/-- If two functions `f` and `g` admit Taylor series `p` and `q` in a set `s`, then the cartesian
product of `f` and `g` admits the cartesian product of `p` and `q` as a Taylor series. -/
lemma has_ftaylor_series_up_to_on.prod {n : with_top ℕ} (hf : has_ftaylor_series_up_to_on n f p s)
{g : E → G} {q : E → formal_multilinear_series 𝕜 E G} (hg : has_ftaylor_series_up_to_on n g q s) :
has_ftaylor_series_up_to_on n (λ y, (f y, g y)) (λ y k, (p y k).prod (q y k)) s :=
begin
set L := λ m, continuous_multilinear_map.prodL 𝕜 (λ i : fin m, E) F G,
split,
{ assume x hx, rw [← hf.zero_eq x hx, ← hg.zero_eq x hx], refl },
{ assume m hm x hx,
convert (L m).has_fderiv_at.comp_has_fderiv_within_at x
((hf.fderiv_within m hm x hx).prod (hg.fderiv_within m hm x hx)) },
{ assume m hm,
exact (L m).continuous.comp_continuous_on ((hf.cont m hm).prod (hg.cont m hm)) }
end
/-- The cartesian product of `C^n` functions at a point in a domain is `C^n`. -/
lemma times_cont_diff_within_at.prod {n : with_top ℕ} {s : set E} {f : E → F} {g : E → G}
(hf : times_cont_diff_within_at 𝕜 n f s x) (hg : times_cont_diff_within_at 𝕜 n g s x) :
times_cont_diff_within_at 𝕜 n (λx:E, (f x, g x)) s x :=
begin
assume m hm,
rcases hf m hm with ⟨u, hu, p, hp⟩,
rcases hg m hm with ⟨v, hv, q, hq⟩,
exact ⟨u ∩ v, filter.inter_mem hu hv, _,
(hp.mono (inter_subset_left u v)).prod (hq.mono (inter_subset_right u v))⟩
end
/-- The cartesian product of `C^n` functions on domains is `C^n`. -/
lemma times_cont_diff_on.prod {n : with_top ℕ} {s : set E} {f : E → F} {g : E → G}
(hf : times_cont_diff_on 𝕜 n f s) (hg : times_cont_diff_on 𝕜 n g s) :
times_cont_diff_on 𝕜 n (λx:E, (f x, g x)) s :=
λ x hx, (hf x hx).prod (hg x hx)
/-- The cartesian product of `C^n` functions at a point is `C^n`. -/
lemma times_cont_diff_at.prod {n : with_top ℕ} {f : E → F} {g : E → G}
(hf : times_cont_diff_at 𝕜 n f x) (hg : times_cont_diff_at 𝕜 n g x) :
times_cont_diff_at 𝕜 n (λx:E, (f x, g x)) x :=
times_cont_diff_within_at_univ.1 $ times_cont_diff_within_at.prod
(times_cont_diff_within_at_univ.2 hf)
(times_cont_diff_within_at_univ.2 hg)
/--
The cartesian product of `C^n` functions is `C^n`.
-/
lemma times_cont_diff.prod {n : with_top ℕ} {f : E → F} {g : E → G}
(hf : times_cont_diff 𝕜 n f) (hg : times_cont_diff 𝕜 n g) :
times_cont_diff 𝕜 n (λx:E, (f x, g x)) :=
times_cont_diff_on_univ.1 $ times_cont_diff_on.prod (times_cont_diff_on_univ.2 hf)
(times_cont_diff_on_univ.2 hg)
/-!
### Smoothness of functions `f : E → Π i, F' i`
-/
section pi
variables {ι : Type*} [fintype ι] {F' : ι → Type*} [Π i, normed_group (F' i)]
[Π i, normed_space 𝕜 (F' i)] {φ : Π i, E → F' i}
{p' : Π i, E → formal_multilinear_series 𝕜 E (F' i)}
{Φ : E → Π i, F' i} {P' : E → formal_multilinear_series 𝕜 E (Π i, F' i)}
{n : with_top ℕ}
lemma has_ftaylor_series_up_to_on_pi :
has_ftaylor_series_up_to_on n (λ x i, φ i x)
(λ x m, continuous_multilinear_map.pi (λ i, p' i x m)) s ↔
∀ i, has_ftaylor_series_up_to_on n (φ i) (p' i) s :=
begin
set pr := @continuous_linear_map.proj 𝕜 _ ι F' _ _ _,
letI : Π (m : ℕ) (i : ι), normed_space 𝕜 (E [×m]→L[𝕜] (F' i)) := λ m i, infer_instance,
set L : Π m : ℕ, (Π i, E [×m]→L[𝕜] (F' i)) ≃ₗᵢ[𝕜] (E [×m]→L[𝕜] (Π i, F' i)) :=
λ m, continuous_multilinear_map.piₗᵢ _ _,
refine ⟨λ h i, _, λ h, ⟨λ x hx, _, _, _⟩⟩,
{ convert h.continuous_linear_map_comp (pr i),
ext, refl },
{ ext1 i,
exact (h i).zero_eq x hx },
{ intros m hm x hx,
have := has_fderiv_within_at_pi.2 (λ i, (h i).fderiv_within m hm x hx),
convert (L m).has_fderiv_at.comp_has_fderiv_within_at x this },
{ intros m hm,
have := continuous_on_pi.2 (λ i, (h i).cont m hm),
convert (L m).continuous.comp_continuous_on this }
end
@[simp] lemma has_ftaylor_series_up_to_on_pi' :
has_ftaylor_series_up_to_on n Φ P' s ↔
∀ i, has_ftaylor_series_up_to_on n (λ x, Φ x i)
(λ x m, (@continuous_linear_map.proj 𝕜 _ ι F' _ _ _ i).comp_continuous_multilinear_map
(P' x m)) s :=
by { convert has_ftaylor_series_up_to_on_pi, ext, refl }
lemma times_cont_diff_within_at_pi :
times_cont_diff_within_at 𝕜 n Φ s x ↔
∀ i, times_cont_diff_within_at 𝕜 n (λ x, Φ x i) s x :=
begin
set pr := @continuous_linear_map.proj 𝕜 _ ι F' _ _ _,
refine ⟨λ h i, h.continuous_linear_map_comp (pr i), λ h m hm, _⟩,
choose u hux p hp using λ i, h i m hm,
exact ⟨⋂ i, u i, filter.Inter_mem.2 hux, _,
has_ftaylor_series_up_to_on_pi.2 (λ i, (hp i).mono $ Inter_subset _ _)⟩,
end
lemma times_cont_diff_on_pi :
times_cont_diff_on 𝕜 n Φ s ↔ ∀ i, times_cont_diff_on 𝕜 n (λ x, Φ x i) s :=
⟨λ h i x hx, times_cont_diff_within_at_pi.1 (h x hx) _,
λ h x hx, times_cont_diff_within_at_pi.2 (λ i, h i x hx)⟩
lemma times_cont_diff_at_pi :
times_cont_diff_at 𝕜 n Φ x ↔ ∀ i, times_cont_diff_at 𝕜 n (λ x, Φ x i) x :=
times_cont_diff_within_at_pi
lemma times_cont_diff_pi :
times_cont_diff 𝕜 n Φ ↔ ∀ i, times_cont_diff 𝕜 n (λ x, Φ x i) :=
by simp only [← times_cont_diff_on_univ, times_cont_diff_on_pi]
end pi
/-!
### Composition of `C^n` functions
We show that the composition of `C^n` functions is `C^n`. One way to prove it would be to write
the `n`-th derivative of the composition (this is Faà di Bruno's formula) and check its continuity,
but this is very painful. Instead, we go for a simple inductive proof. Assume it is done for `n`.
Then, to check it for `n+1`, one needs to check that the derivative of `g ∘ f` is `C^n`, i.e.,
that `Dg(f x) ⬝ Df(x)` is `C^n`. The term `Dg (f x)` is the composition of two `C^n` functions, so
it is `C^n` by the inductive assumption. The term `Df(x)` is also `C^n`. Then, the matrix
multiplication is the application of a bilinear map (which is `C^∞`, and therefore `C^n`) to
`x ↦ (Dg(f x), Df x)`. As the composition of two `C^n` maps, it is again `C^n`, and we are done.
There is a subtlety in this argument: we apply the inductive assumption to functions on other Banach
spaces. In maths, one would say: prove by induction over `n` that, for all `C^n` maps between all
pairs of Banach spaces, their composition is `C^n`. In Lean, this is fine as long as the spaces
stay in the same universe. This is not the case in the above argument: if `E` lives in universe `u`
and `F` lives in universe `v`, then linear maps from `E` to `F` (to which the derivative of `f`
belongs) is in universe `max u v`. If one could quantify over finitely many universes, the above
proof would work fine, but this is not the case. One could still write the proof considering spaces
in any universe in `u, v, w, max u v, max v w, max u v w`, but it would be extremely tedious and
lead to a lot of duplication. Instead, we formulate the above proof when all spaces live in the same
universe (where everything is fine), and then we deduce the general result by lifting all our spaces
to a common universe. We use the trick that any space `H` is isomorphic through a continuous linear
equiv to `continuous_multilinear_map (λ (i : fin 0), E × F × G) H` to change the universe level,
and then argue that composing with such a linear equiv does not change the fact of being `C^n`,
which we have already proved previously.
-/
/-- Auxiliary lemma proving that the composition of `C^n` functions on domains is `C^n` when all
spaces live in the same universe. Use instead `times_cont_diff_on.comp` which removes the universe
assumption (but is deduced from this one). -/
private lemma times_cont_diff_on.comp_same_univ
{Eu : Type u} [normed_group Eu] [normed_space 𝕜 Eu]
{Fu : Type u} [normed_group Fu] [normed_space 𝕜 Fu]
{Gu : Type u} [normed_group Gu] [normed_space 𝕜 Gu]
{n : with_top ℕ} {s : set Eu} {t : set Fu} {g : Fu → Gu} {f : Eu → Fu}
(hg : times_cont_diff_on 𝕜 n g t) (hf : times_cont_diff_on 𝕜 n f s) (st : s ⊆ f ⁻¹' t) :
times_cont_diff_on 𝕜 n (g ∘ f) s :=
begin
unfreezingI { induction n using with_top.nat_induction with n IH Itop generalizing Eu Fu Gu },
{ rw times_cont_diff_on_zero at hf hg ⊢,
exact continuous_on.comp hg hf st },
{ rw times_cont_diff_on_succ_iff_has_fderiv_within_at at hg ⊢,
assume x hx,
rcases (times_cont_diff_on_succ_iff_has_fderiv_within_at.1 hf) x hx
with ⟨u, hu, f', hf', f'_diff⟩,
rcases hg (f x) (st hx) with ⟨v, hv, g', hg', g'_diff⟩,
rw insert_eq_of_mem hx at hu ⊢,
have xu : x ∈ u := mem_of_mem_nhds_within hx hu,
let w := s ∩ (u ∩ f⁻¹' v),
have wv : w ⊆ f ⁻¹' v := λ y hy, hy.2.2,
have wu : w ⊆ u := λ y hy, hy.2.1,
have ws : w ⊆ s := λ y hy, hy.1,
refine ⟨w, _, λ y, (g' (f y)).comp (f' y), _, _⟩,
show w ∈ 𝓝[s] x,
{ apply filter.inter_mem self_mem_nhds_within,
apply filter.inter_mem hu,
apply continuous_within_at.preimage_mem_nhds_within',
{ rw ← continuous_within_at_inter' hu,
exact (hf' x xu).differentiable_within_at.continuous_within_at.mono
(inter_subset_right _ _) },
{ apply nhds_within_mono _ _ hv,
exact subset.trans (image_subset_iff.mpr st) (subset_insert (f x) t) } },
show ∀ y ∈ w,
has_fderiv_within_at (g ∘ f) ((g' (f y)).comp (f' y)) w y,
{ rintros y ⟨ys, yu, yv⟩,
exact (hg' (f y) yv).comp y ((hf' y yu).mono wu) wv },
show times_cont_diff_on 𝕜 n (λ y, (g' (f y)).comp (f' y)) w,
{ have A : times_cont_diff_on 𝕜 n (λ y, g' (f y)) w :=
IH g'_diff ((hf.of_le (with_top.coe_le_coe.2 (nat.le_succ n))).mono ws) wv,
have B : times_cont_diff_on 𝕜 n f' w := f'_diff.mono wu,
have C : times_cont_diff_on 𝕜 n (λ y, (f' y, g' (f y))) w :=
times_cont_diff_on.prod B A,
have D : times_cont_diff_on 𝕜 n (λ(p : (Eu →L[𝕜] Fu) × (Fu →L[𝕜] Gu)), p.2.comp p.1) univ :=
is_bounded_bilinear_map_comp.times_cont_diff.times_cont_diff_on,
exact IH D C (subset_univ _) } },
{ rw times_cont_diff_on_top at hf hg ⊢,
assume n,
apply Itop n (hg n) (hf n) st }
end
/-- The composition of `C^n` functions on domains is `C^n`. -/
lemma times_cont_diff_on.comp
{n : with_top ℕ} {s : set E} {t : set F} {g : F → G} {f : E → F}
(hg : times_cont_diff_on 𝕜 n g t) (hf : times_cont_diff_on 𝕜 n f s) (st : s ⊆ f ⁻¹' t) :
times_cont_diff_on 𝕜 n (g ∘ f) s :=
begin
/- we lift all the spaces to a common universe, as we have already proved the result in this
situation. For the lift, we use the trick that `H` is isomorphic through a
continuous linear equiv to `continuous_multilinear_map 𝕜 (λ (i : fin 0), (E × F × G)) H`, and
continuous linear equivs respect smoothness classes. -/
let Eu := continuous_multilinear_map 𝕜 (λ (i : fin 0), (E × F × G)) E,
letI : normed_group Eu := by apply_instance,
letI : normed_space 𝕜 Eu := by apply_instance,
let Fu := continuous_multilinear_map 𝕜 (λ (i : fin 0), (E × F × G)) F,
letI : normed_group Fu := by apply_instance,
letI : normed_space 𝕜 Fu := by apply_instance,
let Gu := continuous_multilinear_map 𝕜 (λ (i : fin 0), (E × F × G)) G,
letI : normed_group Gu := by apply_instance,
letI : normed_space 𝕜 Gu := by apply_instance,
-- declare the isomorphisms
let isoE : Eu ≃L[𝕜] E := continuous_multilinear_curry_fin0 𝕜 (E × F × G) E,
let isoF : Fu ≃L[𝕜] F := continuous_multilinear_curry_fin0 𝕜 (E × F × G) F,
let isoG : Gu ≃L[𝕜] G := continuous_multilinear_curry_fin0 𝕜 (E × F × G) G,
-- lift the functions to the new spaces, check smoothness there, and then go back.
let fu : Eu → Fu := (isoF.symm ∘ f) ∘ isoE,
have fu_diff : times_cont_diff_on 𝕜 n fu (isoE ⁻¹' s),
by rwa [isoE.times_cont_diff_on_comp_iff, isoF.symm.comp_times_cont_diff_on_iff],
let gu : Fu → Gu := (isoG.symm ∘ g) ∘ isoF,
have gu_diff : times_cont_diff_on 𝕜 n gu (isoF ⁻¹' t),
by rwa [isoF.times_cont_diff_on_comp_iff, isoG.symm.comp_times_cont_diff_on_iff],
have main : times_cont_diff_on 𝕜 n (gu ∘ fu) (isoE ⁻¹' s),
{ apply times_cont_diff_on.comp_same_univ gu_diff fu_diff,
assume y hy,
simp only [fu, continuous_linear_equiv.coe_apply, function.comp_app, mem_preimage],
rw isoF.apply_symm_apply (f (isoE y)),
exact st hy },
have : gu ∘ fu = (isoG.symm ∘ (g ∘ f)) ∘ isoE,
{ ext y,
simp only [function.comp_apply, gu, fu],
rw isoF.apply_symm_apply (f (isoE y)) },
rwa [this, isoE.times_cont_diff_on_comp_iff, isoG.symm.comp_times_cont_diff_on_iff] at main
end
/-- The composition of `C^n` functions on domains is `C^n`. -/
lemma times_cont_diff_on.comp'
{n : with_top ℕ} {s : set E} {t : set F} {g : F → G} {f : E → F}
(hg : times_cont_diff_on 𝕜 n g t) (hf : times_cont_diff_on 𝕜 n f s) :
times_cont_diff_on 𝕜 n (g ∘ f) (s ∩ f⁻¹' t) :=
hg.comp (hf.mono (inter_subset_left _ _)) (inter_subset_right _ _)
/-- The composition of a `C^n` function on a domain with a `C^n` function is `C^n`. -/
lemma times_cont_diff.comp_times_cont_diff_on {n : with_top ℕ} {s : set E} {g : F → G} {f : E → F}
(hg : times_cont_diff 𝕜 n g) (hf : times_cont_diff_on 𝕜 n f s) :
times_cont_diff_on 𝕜 n (g ∘ f) s :=
(times_cont_diff_on_univ.2 hg).comp hf subset_preimage_univ
/-- The composition of `C^n` functions is `C^n`. -/
lemma times_cont_diff.comp {n : with_top ℕ} {g : F → G} {f : E → F}
(hg : times_cont_diff 𝕜 n g) (hf : times_cont_diff 𝕜 n f) :
times_cont_diff 𝕜 n (g ∘ f) :=
times_cont_diff_on_univ.1 $ times_cont_diff_on.comp (times_cont_diff_on_univ.2 hg)
(times_cont_diff_on_univ.2 hf) (subset_univ _)
/-- The composition of `C^n` functions at points in domains is `C^n`. -/
lemma times_cont_diff_within_at.comp
{n : with_top ℕ} {s : set E} {t : set F} {g : F → G} {f : E → F} (x : E)
(hg : times_cont_diff_within_at 𝕜 n g t (f x))
(hf : times_cont_diff_within_at 𝕜 n f s x) (st : s ⊆ f ⁻¹' t) :
times_cont_diff_within_at 𝕜 n (g ∘ f) s x :=
begin
assume m hm,
rcases hg.times_cont_diff_on hm with ⟨u, u_nhd, ut, hu⟩,
rcases hf.times_cont_diff_on hm with ⟨v, v_nhd, vs, hv⟩,
have xmem : x ∈ f ⁻¹' u ∩ v :=
⟨(mem_of_mem_nhds_within (mem_insert (f x) _) u_nhd : _),
mem_of_mem_nhds_within (mem_insert x s) v_nhd⟩,
have : f ⁻¹' u ∈ 𝓝[insert x s] x,
{ apply hf.continuous_within_at.insert_self.preimage_mem_nhds_within',
apply nhds_within_mono _ _ u_nhd,
rw image_insert_eq,
exact insert_subset_insert (image_subset_iff.mpr st) },
have Z := ((hu.comp (hv.mono (inter_subset_right (f ⁻¹' u) v)) (inter_subset_left _ _))
.times_cont_diff_within_at) xmem m (le_refl _),
have : 𝓝[f ⁻¹' u ∩ v] x = 𝓝[insert x s] x,
{ have A : f ⁻¹' u ∩ v = (insert x s) ∩ (f ⁻¹' u ∩ v),
{ apply subset.antisymm _ (inter_subset_right _ _),
rintros y ⟨hy1, hy2⟩,
simp [hy1, hy2, vs hy2] },
rw [A, ← nhds_within_restrict''],
exact filter.inter_mem this v_nhd },
rwa [insert_eq_of_mem xmem, this] at Z,
end
/-- The composition of `C^n` functions at points in domains is `C^n`. -/
lemma times_cont_diff_within_at.comp' {n : with_top ℕ} {s : set E} {t : set F} {g : F → G}
{f : E → F} (x : E)
(hg : times_cont_diff_within_at 𝕜 n g t (f x)) (hf : times_cont_diff_within_at 𝕜 n f s x) :
times_cont_diff_within_at 𝕜 n (g ∘ f) (s ∩ f⁻¹' t) x :=
hg.comp x (hf.mono (inter_subset_left _ _)) (inter_subset_right _ _)
lemma times_cont_diff_at.comp_times_cont_diff_within_at {n} (x : E)
(hg : times_cont_diff_at 𝕜 n g (f x)) (hf : times_cont_diff_within_at 𝕜 n f s x) :
times_cont_diff_within_at 𝕜 n (g ∘ f) s x :=
hg.comp x hf (maps_to_univ _ _)
/-- The composition of `C^n` functions at points is `C^n`. -/
lemma times_cont_diff_at.comp {n : with_top ℕ} (x : E)
(hg : times_cont_diff_at 𝕜 n g (f x))
(hf : times_cont_diff_at 𝕜 n f x) :
times_cont_diff_at 𝕜 n (g ∘ f) x :=
hg.comp x hf subset_preimage_univ
lemma times_cont_diff.comp_times_cont_diff_within_at
{n : with_top ℕ} {g : F → G} {f : E → F} (h : times_cont_diff 𝕜 n g)
(hf : times_cont_diff_within_at 𝕜 n f t x) :
times_cont_diff_within_at 𝕜 n (g ∘ f) t x :=
begin
have : times_cont_diff_within_at 𝕜 n g univ (f x) :=
h.times_cont_diff_at.times_cont_diff_within_at,
exact this.comp x hf (subset_univ _),
end
lemma times_cont_diff.comp_times_cont_diff_at
{n : with_top ℕ} {g : F → G} {f : E → F} (x : E)
(hg : times_cont_diff 𝕜 n g)
(hf : times_cont_diff_at 𝕜 n f x) :
times_cont_diff_at 𝕜 n (g ∘ f) x :=
hg.comp_times_cont_diff_within_at hf
/-- The bundled derivative of a `C^{n+1}` function is `C^n`. -/
lemma times_cont_diff_on_fderiv_within_apply {m n : with_top ℕ} {s : set E}
{f : E → F} (hf : times_cont_diff_on 𝕜 n f s) (hs : unique_diff_on 𝕜 s) (hmn : m + 1 ≤ n) :
times_cont_diff_on 𝕜 m (λp : E × E, (fderiv_within 𝕜 f s p.1 : E →L[𝕜] F) p.2)
(set.prod s (univ : set E)) :=
begin
have A : times_cont_diff 𝕜 m (λp : (E →L[𝕜] F) × E, p.1 p.2),
{ apply is_bounded_bilinear_map.times_cont_diff,
exact is_bounded_bilinear_map_apply },
have B : times_cont_diff_on 𝕜 m
(λ (p : E × E), ((fderiv_within 𝕜 f s p.fst), p.snd)) (set.prod s univ),
{ apply times_cont_diff_on.prod _ _,
{ have I : times_cont_diff_on 𝕜 m (λ (x : E), fderiv_within 𝕜 f s x) s :=
hf.fderiv_within hs hmn,
have J : times_cont_diff_on 𝕜 m (λ (x : E × E), x.1) (set.prod s univ) :=
times_cont_diff_fst.times_cont_diff_on,
exact times_cont_diff_on.comp I J (prod_subset_preimage_fst _ _) },
{ apply times_cont_diff.times_cont_diff_on _ ,
apply is_bounded_linear_map.snd.times_cont_diff } },
exact A.comp_times_cont_diff_on B
end
/-- The bundled derivative of a `C^{n+1}` function is `C^n`. -/
lemma times_cont_diff.times_cont_diff_fderiv_apply {n m : with_top ℕ} {f : E → F}
(hf : times_cont_diff 𝕜 n f) (hmn : m + 1 ≤ n) :
times_cont_diff 𝕜 m (λp : E × E, (fderiv 𝕜 f p.1 : E →L[𝕜] F) p.2) :=
begin
rw ← times_cont_diff_on_univ at ⊢ hf,
rw [← fderiv_within_univ, ← univ_prod_univ],
exact times_cont_diff_on_fderiv_within_apply hf unique_diff_on_univ hmn
end
/-! ### Sum of two functions -/
/- The sum is smooth. -/
lemma times_cont_diff_add {n : with_top ℕ} :
times_cont_diff 𝕜 n (λp : F × F, p.1 + p.2) :=
(is_bounded_linear_map.fst.add is_bounded_linear_map.snd).times_cont_diff
/-- The sum of two `C^n` functions within a set at a point is `C^n` within this set
at this point. -/
lemma times_cont_diff_within_at.add {n : with_top ℕ} {s : set E} {f g : E → F}
(hf : times_cont_diff_within_at 𝕜 n f s x) (hg : times_cont_diff_within_at 𝕜 n g s x) :
times_cont_diff_within_at 𝕜 n (λx, f x + g x) s x :=
times_cont_diff_add.times_cont_diff_within_at.comp x (hf.prod hg) subset_preimage_univ
/-- The sum of two `C^n` functions at a point is `C^n` at this point. -/
lemma times_cont_diff_at.add {n : with_top ℕ} {f g : E → F}
(hf : times_cont_diff_at 𝕜 n f x) (hg : times_cont_diff_at 𝕜 n g x) :
times_cont_diff_at 𝕜 n (λx, f x + g x) x :=
by rw [← times_cont_diff_within_at_univ] at *; exact hf.add hg
/-- The sum of two `C^n`functions is `C^n`. -/
lemma times_cont_diff.add {n : with_top ℕ} {f g : E → F}
(hf : times_cont_diff 𝕜 n f) (hg : times_cont_diff 𝕜 n g) :
times_cont_diff 𝕜 n (λx, f x + g x) :=
times_cont_diff_add.comp (hf.prod hg)
/-- The sum of two `C^n` functions on a domain is `C^n`. -/
lemma times_cont_diff_on.add {n : with_top ℕ} {s : set E} {f g : E → F}
(hf : times_cont_diff_on 𝕜 n f s) (hg : times_cont_diff_on 𝕜 n g s) :
times_cont_diff_on 𝕜 n (λx, f x + g x) s :=
λ x hx, (hf x hx).add (hg x hx)
/-! ### Negative -/
/- The negative is smooth. -/
lemma times_cont_diff_neg {n : with_top ℕ} :
times_cont_diff 𝕜 n (λp : F, -p) :=
is_bounded_linear_map.id.neg.times_cont_diff
/-- The negative of a `C^n` function within a domain at a point is `C^n` within this domain at
this point. -/
lemma times_cont_diff_within_at.neg {n : with_top ℕ} {s : set E} {f : E → F}
(hf : times_cont_diff_within_at 𝕜 n f s x) : times_cont_diff_within_at 𝕜 n (λx, -f x) s x :=
times_cont_diff_neg.times_cont_diff_within_at.comp x hf subset_preimage_univ
/-- The negative of a `C^n` function at a point is `C^n` at this point. -/
lemma times_cont_diff_at.neg {n : with_top ℕ} {f : E → F}
(hf : times_cont_diff_at 𝕜 n f x) : times_cont_diff_at 𝕜 n (λx, -f x) x :=
by rw ← times_cont_diff_within_at_univ at *; exact hf.neg
/-- The negative of a `C^n`function is `C^n`. -/
lemma times_cont_diff.neg {n : with_top ℕ} {f : E → F} (hf : times_cont_diff 𝕜 n f) :
times_cont_diff 𝕜 n (λx, -f x) :=
times_cont_diff_neg.comp hf
/-- The negative of a `C^n` function on a domain is `C^n`. -/
lemma times_cont_diff_on.neg {n : with_top ℕ} {s : set E} {f : E → F}
(hf : times_cont_diff_on 𝕜 n f s) : times_cont_diff_on 𝕜 n (λx, -f x) s :=
λ x hx, (hf x hx).neg
/-! ### Subtraction -/
/-- The difference of two `C^n` functions within a set at a point is `C^n` within this set
at this point. -/
lemma times_cont_diff_within_at.sub {n : with_top ℕ} {s : set E} {f g : E → F}
(hf : times_cont_diff_within_at 𝕜 n f s x) (hg : times_cont_diff_within_at 𝕜 n g s x) :
times_cont_diff_within_at 𝕜 n (λx, f x - g x) s x :=
by simpa only [sub_eq_add_neg] using hf.add hg.neg
/-- The difference of two `C^n` functions at a point is `C^n` at this point. -/
lemma times_cont_diff_at.sub {n : with_top ℕ} {f g : E → F}
(hf : times_cont_diff_at 𝕜 n f x) (hg : times_cont_diff_at 𝕜 n g x) :
times_cont_diff_at 𝕜 n (λx, f x - g x) x :=
by simpa only [sub_eq_add_neg] using hf.add hg.neg
/-- The difference of two `C^n` functions on a domain is `C^n`. -/
lemma times_cont_diff_on.sub {n : with_top ℕ} {s : set E} {f g : E → F}
(hf : times_cont_diff_on 𝕜 n f s) (hg : times_cont_diff_on 𝕜 n g s) :
times_cont_diff_on 𝕜 n (λx, f x - g x) s :=
by simpa only [sub_eq_add_neg] using hf.add hg.neg
/-- The difference of two `C^n` functions is `C^n`. -/
lemma times_cont_diff.sub {n : with_top ℕ} {f g : E → F}
(hf : times_cont_diff 𝕜 n f) (hg : times_cont_diff 𝕜 n g) : times_cont_diff 𝕜 n (λx, f x - g x) :=
by simpa only [sub_eq_add_neg] using hf.add hg.neg
/-! ### Sum of finitely many functions -/
lemma times_cont_diff_within_at.sum
{ι : Type*} {f : ι → E → F} {s : finset ι} {n : with_top ℕ} {t : set E} {x : E}
(h : ∀ i ∈ s, times_cont_diff_within_at 𝕜 n (λ x, f i x) t x) :
times_cont_diff_within_at 𝕜 n (λ x, (∑ i in s, f i x)) t x :=
begin
classical,
induction s using finset.induction_on with i s is IH,
{ simp [times_cont_diff_within_at_const] },
{ simp only [is, finset.sum_insert, not_false_iff],
exact (h _ (finset.mem_insert_self i s)).add (IH (λ j hj, h _ (finset.mem_insert_of_mem hj))) }
end
lemma times_cont_diff_at.sum
{ι : Type*} {f : ι → E → F} {s : finset ι} {n : with_top ℕ} {x : E}
(h : ∀ i ∈ s, times_cont_diff_at 𝕜 n (λ x, f i x) x) :
times_cont_diff_at 𝕜 n (λ x, (∑ i in s, f i x)) x :=
by rw [← times_cont_diff_within_at_univ] at *; exact times_cont_diff_within_at.sum h
lemma times_cont_diff_on.sum
{ι : Type*} {f : ι → E → F} {s : finset ι} {n : with_top ℕ} {t : set E}
(h : ∀ i ∈ s, times_cont_diff_on 𝕜 n (λ x, f i x) t) :
times_cont_diff_on 𝕜 n (λ x, (∑ i in s, f i x)) t :=
λ x hx, times_cont_diff_within_at.sum (λ i hi, h i hi x hx)
lemma times_cont_diff.sum
{ι : Type*} {f : ι → E → F} {s : finset ι} {n : with_top ℕ}
(h : ∀ i ∈ s, times_cont_diff 𝕜 n (λ x, f i x)) :
times_cont_diff 𝕜 n (λ x, (∑ i in s, f i x)) :=
by simp [← times_cont_diff_on_univ] at *; exact times_cont_diff_on.sum h
/-! ### Product of two functions -/
/- The product is smooth. -/
lemma times_cont_diff_mul {n : with_top ℕ} :
times_cont_diff 𝕜 n (λ p : 𝕜 × 𝕜, p.1 * p.2) :=
is_bounded_bilinear_map_mul.times_cont_diff
/-- The product of two `C^n` functions within a set at a point is `C^n` within this set
at this point. -/
lemma times_cont_diff_within_at.mul {n : with_top ℕ} {s : set E} {f g : E → 𝕜}
(hf : times_cont_diff_within_at 𝕜 n f s x) (hg : times_cont_diff_within_at 𝕜 n g s x) :
times_cont_diff_within_at 𝕜 n (λ x, f x * g x) s x :=
times_cont_diff_mul.times_cont_diff_within_at.comp x (hf.prod hg) subset_preimage_univ
/-- The product of two `C^n` functions at a point is `C^n` at this point. -/
lemma times_cont_diff_at.mul {n : with_top ℕ} {f g : E → 𝕜}
(hf : times_cont_diff_at 𝕜 n f x) (hg : times_cont_diff_at 𝕜 n g x) :
times_cont_diff_at 𝕜 n (λ x, f x * g x) x :=
by rw [← times_cont_diff_within_at_univ] at *; exact hf.mul hg
/-- The product of two `C^n` functions on a domain is `C^n`. -/
lemma times_cont_diff_on.mul {n : with_top ℕ} {s : set E} {f g : E → 𝕜}
(hf : times_cont_diff_on 𝕜 n f s) (hg : times_cont_diff_on 𝕜 n g s) :
times_cont_diff_on 𝕜 n (λ x, f x * g x) s :=
λ x hx, (hf x hx).mul (hg x hx)
/-- The product of two `C^n`functions is `C^n`. -/
lemma times_cont_diff.mul {n : with_top ℕ} {f g : E → 𝕜}
(hf : times_cont_diff 𝕜 n f) (hg : times_cont_diff 𝕜 n g) :
times_cont_diff 𝕜 n (λ x, f x * g x) :=
times_cont_diff_mul.comp (hf.prod hg)
lemma times_cont_diff_within_at.div_const {f : E → 𝕜} {n} {c : 𝕜}
(hf : times_cont_diff_within_at 𝕜 n f s x) :
times_cont_diff_within_at 𝕜 n (λ x, f x / c) s x :=
by simpa only [div_eq_mul_inv] using hf.mul times_cont_diff_within_at_const
lemma times_cont_diff_at.div_const {f : E → 𝕜} {n} {c : 𝕜} (hf : times_cont_diff_at 𝕜 n f x) :
times_cont_diff_at 𝕜 n (λ x, f x / c) x :=
by simpa only [div_eq_mul_inv] using hf.mul times_cont_diff_at_const
lemma times_cont_diff_on.div_const {f : E → 𝕜} {n} {c : 𝕜} (hf : times_cont_diff_on 𝕜 n f s) :
times_cont_diff_on 𝕜 n (λ x, f x / c) s :=
by simpa only [div_eq_mul_inv] using hf.mul times_cont_diff_on_const
lemma times_cont_diff.div_const {f : E → 𝕜} {n} {c : 𝕜} (hf : times_cont_diff 𝕜 n f) :
times_cont_diff 𝕜 n (λ x, f x / c) :=
by simpa only [div_eq_mul_inv] using hf.mul times_cont_diff_const
lemma times_cont_diff.pow {n : with_top ℕ} {f : E → 𝕜}
(hf : times_cont_diff 𝕜 n f) :
∀ m : ℕ, times_cont_diff 𝕜 n (λ x, (f x) ^ m)
| 0 := by simpa using times_cont_diff_const
| (m + 1) := by simpa [pow_succ] using hf.mul (times_cont_diff.pow m)
lemma times_cont_diff_at.pow {n : with_top ℕ} {f : E → 𝕜} (hf : times_cont_diff_at 𝕜 n f x)
(m : ℕ) : times_cont_diff_at 𝕜 n (λ y, f y ^ m) x :=
(times_cont_diff_id.pow m).times_cont_diff_at.comp x hf
lemma times_cont_diff_within_at.pow {n : with_top ℕ} {f : E → 𝕜}
(hf : times_cont_diff_within_at 𝕜 n f s x) (m : ℕ) :
times_cont_diff_within_at 𝕜 n (λ y, f y ^ m) s x :=
(times_cont_diff_id.pow m).times_cont_diff_at.comp_times_cont_diff_within_at x hf
lemma times_cont_diff_on.pow {n : with_top ℕ} {f : E → 𝕜}
(hf : times_cont_diff_on 𝕜 n f s) (m : ℕ) :
times_cont_diff_on 𝕜 n (λ y, f y ^ m) s :=
λ y hy, (hf y hy).pow m
/-! ### Scalar multiplication -/
/- The scalar multiplication is smooth. -/
lemma times_cont_diff_smul {n : with_top ℕ} :
times_cont_diff 𝕜 n (λ p : 𝕜 × F, p.1 • p.2) :=
is_bounded_bilinear_map_smul.times_cont_diff
/-- The scalar multiplication of two `C^n` functions within a set at a point is `C^n` within this
set at this point. -/
lemma times_cont_diff_within_at.smul {n : with_top ℕ} {s : set E} {f : E → 𝕜} {g : E → F}
(hf : times_cont_diff_within_at 𝕜 n f s x) (hg : times_cont_diff_within_at 𝕜 n g s x) :
times_cont_diff_within_at 𝕜 n (λ x, f x • g x) s x :=
times_cont_diff_smul.times_cont_diff_within_at.comp x (hf.prod hg) subset_preimage_univ
/-- The scalar multiplication of two `C^n` functions at a point is `C^n` at this point. -/
lemma times_cont_diff_at.smul {n : with_top ℕ} {f : E → 𝕜} {g : E → F}
(hf : times_cont_diff_at 𝕜 n f x) (hg : times_cont_diff_at 𝕜 n g x) :
times_cont_diff_at 𝕜 n (λ x, f x • g x) x :=
by rw [← times_cont_diff_within_at_univ] at *; exact hf.smul hg
/-- The scalar multiplication of two `C^n` functions is `C^n`. -/
lemma times_cont_diff.smul {n : with_top ℕ} {f : E → 𝕜} {g : E → F}
(hf : times_cont_diff 𝕜 n f) (hg : times_cont_diff 𝕜 n g) :
times_cont_diff 𝕜 n (λ x, f x • g x) :=
times_cont_diff_smul.comp (hf.prod hg)
/-- The scalar multiplication of two `C^n` functions on a domain is `C^n`. -/
lemma times_cont_diff_on.smul {n : with_top ℕ} {s : set E} {f : E → 𝕜} {g : E → F}
(hf : times_cont_diff_on 𝕜 n f s) (hg : times_cont_diff_on 𝕜 n g s) :
times_cont_diff_on 𝕜 n (λ x, f x • g x) s :=
λ x hx, (hf x hx).smul (hg x hx)
/-! ### Cartesian product of two functions-/
section prod_map
variables {E' : Type*} [normed_group E'] [normed_space 𝕜 E']
{F' : Type*} [normed_group F'] [normed_space 𝕜 F']
{n : with_top ℕ}
/-- The product map of two `C^n` functions within a set at a point is `C^n`
within the product set at the product point. -/
lemma times_cont_diff_within_at.prod_map'
{s : set E} {t : set E'} {f : E → F} {g : E' → F'} {p : E × E'}
(hf : times_cont_diff_within_at 𝕜 n f s p.1) (hg : times_cont_diff_within_at 𝕜 n g t p.2) :
times_cont_diff_within_at 𝕜 n (prod.map f g) (set.prod s t) p :=
(hf.comp p times_cont_diff_within_at_fst (prod_subset_preimage_fst _ _)).prod
(hg.comp p times_cont_diff_within_at_snd (prod_subset_preimage_snd _ _))
lemma times_cont_diff_within_at.prod_map
{s : set E} {t : set E'} {f : E → F} {g : E' → F'} {x : E} {y : E'}
(hf : times_cont_diff_within_at 𝕜 n f s x) (hg : times_cont_diff_within_at 𝕜 n g t y) :
times_cont_diff_within_at 𝕜 n (prod.map f g) (set.prod s t) (x, y) :=
times_cont_diff_within_at.prod_map' hf hg
/-- The product map of two `C^n` functions on a set is `C^n` on the product set. -/
lemma times_cont_diff_on.prod_map {E' : Type*} [normed_group E'] [normed_space 𝕜 E']
{F' : Type*} [normed_group F'] [normed_space 𝕜 F']
{s : set E} {t : set E'} {n : with_top ℕ} {f : E → F} {g : E' → F'}
(hf : times_cont_diff_on 𝕜 n f s) (hg : times_cont_diff_on 𝕜 n g t) :
times_cont_diff_on 𝕜 n (prod.map f g) (set.prod s t) :=
(hf.comp times_cont_diff_on_fst (prod_subset_preimage_fst _ _)).prod
(hg.comp (times_cont_diff_on_snd) (prod_subset_preimage_snd _ _))
/-- The product map of two `C^n` functions within a set at a point is `C^n`
within the product set at the product point. -/
lemma times_cont_diff_at.prod_map {f : E → F} {g : E' → F'} {x : E} {y : E'}
(hf : times_cont_diff_at 𝕜 n f x) (hg : times_cont_diff_at 𝕜 n g y) :
times_cont_diff_at 𝕜 n (prod.map f g) (x, y) :=
begin
rw times_cont_diff_at at *,
convert hf.prod_map hg,
simp only [univ_prod_univ]
end
/-- The product map of two `C^n` functions within a set at a point is `C^n`
within the product set at the product point. -/
lemma times_cont_diff_at.prod_map' {f : E → F} {g : E' → F'} {p : E × E'}
(hf : times_cont_diff_at 𝕜 n f p.1) (hg : times_cont_diff_at 𝕜 n g p.2) :
times_cont_diff_at 𝕜 n (prod.map f g) p :=
begin
rcases p,
exact times_cont_diff_at.prod_map hf hg
end
/-- The product map of two `C^n` functions is `C^n`. -/
lemma times_cont_diff.prod_map
{f : E → F} {g : E' → F'}
(hf : times_cont_diff 𝕜 n f) (hg : times_cont_diff 𝕜 n g) :
times_cont_diff 𝕜 n (prod.map f g) :=
begin
rw times_cont_diff_iff_times_cont_diff_at at *,
exact λ ⟨x, y⟩, (hf x).prod_map (hg y)
end
end prod_map
/-! ### Inversion in a complete normed algebra -/
section algebra_inverse
variables (𝕜) {R : Type*} [normed_ring R] [normed_algebra 𝕜 R]
open normed_ring continuous_linear_map ring
/-- In a complete normed algebra, the operation of inversion is `C^n`, for all `n`, at each
invertible element. The proof is by induction, bootstrapping using an identity expressing the
derivative of inversion as a bilinear map of inversion itself. -/
lemma times_cont_diff_at_ring_inverse [complete_space R] {n : with_top ℕ} (x : units R) :
times_cont_diff_at 𝕜 n ring.inverse (x : R) :=
begin
induction n using with_top.nat_induction with n IH Itop,
{ intros m hm,
refine ⟨{y : R | is_unit y}, _, _⟩,
{ simp [nhds_within_univ],
exact x.nhds },
{ use (ftaylor_series_within 𝕜 inverse univ),
rw [le_antisymm hm bot_le, has_ftaylor_series_up_to_on_zero_iff],
split,
{ rintros _ ⟨x', rfl⟩,
exact (inverse_continuous_at x').continuous_within_at },
{ simp [ftaylor_series_within] } } },
{ apply times_cont_diff_at_succ_iff_has_fderiv_at.mpr,
refine ⟨λ (x : R), - lmul_left_right 𝕜 R (inverse x) (inverse x), _, _⟩,
{ refine ⟨{y : R | is_unit y}, x.nhds, _⟩,
rintros _ ⟨y, rfl⟩,
rw [inverse_unit],
exact has_fderiv_at_ring_inverse y },
{ convert (lmul_left_right_is_bounded_bilinear 𝕜 R).times_cont_diff.neg.comp_times_cont_diff_at
(x : R) (IH.prod IH) } },
{ exact times_cont_diff_at_top.mpr Itop }
end
variables (𝕜) {𝕜' : Type*} [normed_field 𝕜'] [normed_algebra 𝕜 𝕜'] [complete_space 𝕜']
lemma times_cont_diff_at_inv {x : 𝕜'} (hx : x ≠ 0) {n} :
times_cont_diff_at 𝕜 n has_inv.inv x :=
by simpa only [inverse_eq_has_inv] using times_cont_diff_at_ring_inverse 𝕜 (units.mk0 x hx)
lemma times_cont_diff_on_inv {n} : times_cont_diff_on 𝕜 n (has_inv.inv : 𝕜' → 𝕜') {0}ᶜ :=
λ x hx, (times_cont_diff_at_inv 𝕜 hx).times_cont_diff_within_at
variable {𝕜}
-- TODO: the next few lemmas don't need `𝕜` or `𝕜'` to be complete
-- A good way to show this is to generalize `times_cont_diff_at_ring_inverse` to the setting
-- of a function `f` such that `∀ᶠ x in 𝓝 a, x * f x = 1`.
lemma times_cont_diff_within_at.inv {f : E → 𝕜'} {n} (hf : times_cont_diff_within_at 𝕜 n f s x)
(hx : f x ≠ 0) :
times_cont_diff_within_at 𝕜 n (λ x, (f x)⁻¹) s x :=
(times_cont_diff_at_inv 𝕜 hx).comp_times_cont_diff_within_at x hf
lemma times_cont_diff_on.inv {f : E → 𝕜'} {n} (hf : times_cont_diff_on 𝕜 n f s)
(h : ∀ x ∈ s, f x ≠ 0) :
times_cont_diff_on 𝕜 n (λ x, (f x)⁻¹) s :=
λ x hx, (hf.times_cont_diff_within_at hx).inv (h x hx)
lemma times_cont_diff_at.inv {f : E → 𝕜'} {n} (hf : times_cont_diff_at 𝕜 n f x) (hx : f x ≠ 0) :
times_cont_diff_at 𝕜 n (λ x, (f x)⁻¹) x :=
hf.inv hx
lemma times_cont_diff.inv {f : E → 𝕜'} {n} (hf : times_cont_diff 𝕜 n f) (h : ∀ x, f x ≠ 0) :
times_cont_diff 𝕜 n (λ x, (f x)⁻¹) :=
by { rw times_cont_diff_iff_times_cont_diff_at, exact λ x, hf.times_cont_diff_at.inv (h x) }
-- TODO: generalize to `f g : E → 𝕜'`
lemma times_cont_diff_within_at.div [complete_space 𝕜] {f g : E → 𝕜} {n}
(hf : times_cont_diff_within_at 𝕜 n f s x) (hg : times_cont_diff_within_at 𝕜 n g s x)
(hx : g x ≠ 0) :
times_cont_diff_within_at 𝕜 n (λ x, f x / g x) s x :=
by simpa only [div_eq_mul_inv] using hf.mul (hg.inv hx)
lemma times_cont_diff_on.div [complete_space 𝕜] {f g : E → 𝕜} {n}
(hf : times_cont_diff_on 𝕜 n f s) (hg : times_cont_diff_on 𝕜 n g s) (h₀ : ∀ x ∈ s, g x ≠ 0) :
times_cont_diff_on 𝕜 n (f / g) s :=
λ x hx, (hf x hx).div (hg x hx) (h₀ x hx)
lemma times_cont_diff_at.div [complete_space 𝕜] {f g : E → 𝕜} {n}
(hf : times_cont_diff_at 𝕜 n f x) (hg : times_cont_diff_at 𝕜 n g x)
(hx : g x ≠ 0) :
times_cont_diff_at 𝕜 n (λ x, f x / g x) x :=
hf.div hg hx
lemma times_cont_diff.div [complete_space 𝕜] {f g : E → 𝕜} {n}
(hf : times_cont_diff 𝕜 n f) (hg : times_cont_diff 𝕜 n g)
(h0 : ∀ x, g x ≠ 0) :
times_cont_diff 𝕜 n (λ x, f x / g x) :=
begin
simp only [times_cont_diff_iff_times_cont_diff_at] at *,
exact λ x, (hf x).div (hg x) (h0 x)
end
end algebra_inverse
/-! ### Inversion of continuous linear maps between Banach spaces -/
section map_inverse
open continuous_linear_map
/-- At a continuous linear equivalence `e : E ≃L[𝕜] F` between Banach spaces, the operation of
inversion is `C^n`, for all `n`. -/
lemma times_cont_diff_at_map_inverse [complete_space E] {n : with_top ℕ} (e : E ≃L[𝕜] F) :
times_cont_diff_at 𝕜 n inverse (e : E →L[𝕜] F) :=
begin
nontriviality E,
-- first, we use the lemma `to_ring_inverse` to rewrite in terms of `ring.inverse` in the ring
-- `E →L[𝕜] E`
let O₁ : (E →L[𝕜] E) → (F →L[𝕜] E) := λ f, f.comp (e.symm : (F →L[𝕜] E)),
let O₂ : (E →L[𝕜] F) → (E →L[𝕜] E) := λ f, (e.symm : (F →L[𝕜] E)).comp f,
have : continuous_linear_map.inverse = O₁ ∘ ring.inverse ∘ O₂ :=
funext (to_ring_inverse e),
rw this,
-- `O₁` and `O₂` are `times_cont_diff`,
-- so we reduce to proving that `ring.inverse` is `times_cont_diff`
have h₁ : times_cont_diff 𝕜 n O₁,
from is_bounded_bilinear_map_comp.times_cont_diff.comp
(times_cont_diff_const.prod times_cont_diff_id),
have h₂ : times_cont_diff 𝕜 n O₂,
from is_bounded_bilinear_map_comp.times_cont_diff.comp
(times_cont_diff_id.prod times_cont_diff_const),
refine h₁.times_cont_diff_at.comp _ (times_cont_diff_at.comp _ _ h₂.times_cont_diff_at),
convert times_cont_diff_at_ring_inverse 𝕜 (1 : units (E →L[𝕜] E)),
simp [O₂, one_def]
end
end map_inverse
section function_inverse
open continuous_linear_map
/-- If `f` is a local homeomorphism and the point `a` is in its target,
and if `f` is `n` times continuously differentiable at `f.symm a`,
and if the derivative at `f.symm a` is a continuous linear equivalence,
then `f.symm` is `n` times continuously differentiable at the point `a`.
This is one of the easy parts of the inverse function theorem: it assumes that we already have
an inverse function. -/
theorem local_homeomorph.times_cont_diff_at_symm [complete_space E] {n : with_top ℕ}
(f : local_homeomorph E F) {f₀' : E ≃L[𝕜] F} {a : F} (ha : a ∈ f.target)
(hf₀' : has_fderiv_at f (f₀' : E →L[𝕜] F) (f.symm a)) (hf : times_cont_diff_at 𝕜 n f (f.symm a)) :
times_cont_diff_at 𝕜 n f.symm a :=
begin
-- We prove this by induction on `n`
induction n using with_top.nat_induction with n IH Itop,
{ rw times_cont_diff_at_zero,
exact ⟨f.target, is_open.mem_nhds f.open_target ha, f.continuous_inv_fun⟩ },
{ obtain ⟨f', ⟨u, hu, hff'⟩, hf'⟩ := times_cont_diff_at_succ_iff_has_fderiv_at.mp hf,
apply times_cont_diff_at_succ_iff_has_fderiv_at.mpr,
-- For showing `n.succ` times continuous differentiability (the main inductive step), it
-- suffices to produce the derivative and show that it is `n` times continuously differentiable
have eq_f₀' : f' (f.symm a) = f₀',
{ exact (hff' (f.symm a) (mem_of_mem_nhds hu)).unique hf₀' },
-- This follows by a bootstrapping formula expressing the derivative as a function of `f` itself
refine ⟨inverse ∘ f' ∘ f.symm, _, _⟩,
{ -- We first check that the derivative of `f` is that formula
have h_nhds : {y : E | ∃ (e : E ≃L[𝕜] F), ↑e = f' y} ∈ 𝓝 ((f.symm) a),
{ have hf₀' := f₀'.nhds,
rw ← eq_f₀' at hf₀',
exact hf'.continuous_at.preimage_mem_nhds hf₀' },
obtain ⟨t, htu, ht, htf⟩ := mem_nhds_iff.mp (filter.inter_mem hu h_nhds),
use f.target ∩ (f.symm) ⁻¹' t,
refine ⟨is_open.mem_nhds _ _, _⟩,
{ exact f.preimage_open_of_open_symm ht },
{ exact mem_inter ha (mem_preimage.mpr htf) },
intros x hx,
obtain ⟨hxu, e, he⟩ := htu hx.2,
have h_deriv : has_fderiv_at f ↑e ((f.symm) x),
{ rw he,
exact hff' (f.symm x) hxu },
convert f.has_fderiv_at_symm hx.1 h_deriv,
simp [← he] },
{ -- Then we check that the formula, being a composition of `times_cont_diff` pieces, is
-- itself `times_cont_diff`
have h_deriv₁ : times_cont_diff_at 𝕜 n inverse (f' (f.symm a)),
{ rw eq_f₀',
exact times_cont_diff_at_map_inverse _ },
have h_deriv₂ : times_cont_diff_at 𝕜 n f.symm a,
{ refine IH (hf.of_le _),
norm_cast,
exact nat.le_succ n },
exact (h_deriv₁.comp _ hf').comp _ h_deriv₂ } },
{ refine times_cont_diff_at_top.mpr _,
intros n,
exact Itop n (times_cont_diff_at_top.mp hf n) }
end
/-- Let `f` be a local homeomorphism of a nondiscrete normed field, let `a` be a point in its
target. if `f` is `n` times continuously differentiable at `f.symm a`, and if the derivative at
`f.symm a` is nonzero, then `f.symm` is `n` times continuously differentiable at the point `a`.
This is one of the easy parts of the inverse function theorem: it assumes that we already have
an inverse function. -/
theorem local_homeomorph.times_cont_diff_at_symm_deriv [complete_space 𝕜] {n : with_top ℕ}
(f : local_homeomorph 𝕜 𝕜) {f₀' a : 𝕜} (h₀ : f₀' ≠ 0) (ha : a ∈ f.target)
(hf₀' : has_deriv_at f f₀' (f.symm a)) (hf : times_cont_diff_at 𝕜 n f (f.symm a)) :
times_cont_diff_at 𝕜 n f.symm a :=
f.times_cont_diff_at_symm ha (hf₀'.has_fderiv_at_equiv h₀) hf
end function_inverse
section real
/-!
### Results over `ℝ` or `ℂ`
The results in this section rely on the Mean Value Theorem, and therefore hold only over `ℝ` (and
its extension fields such as `ℂ`).
-/
variables
{𝕂 : Type*} [is_R_or_C 𝕂]
{E' : Type*} [normed_group E'] [normed_space 𝕂 E']
{F' : Type*} [normed_group F'] [normed_space 𝕂 F']
/-- If a function has a Taylor series at order at least 1, then at points in the interior of the
domain of definition, the term of order 1 of this series is a strict derivative of `f`. -/
lemma has_ftaylor_series_up_to_on.has_strict_fderiv_at
{s : set E'} {f : E' → F'} {x : E'} {p : E' → formal_multilinear_series 𝕂 E' F'} {n : with_top ℕ}
(hf : has_ftaylor_series_up_to_on n f p s) (hn : 1 ≤ n) (hs : s ∈ 𝓝 x) :
has_strict_fderiv_at f ((continuous_multilinear_curry_fin1 𝕂 E' F') (p x 1)) x :=
has_strict_fderiv_at_of_has_fderiv_at_of_continuous_at (hf.eventually_has_fderiv_at hn hs) $
(continuous_multilinear_curry_fin1 𝕂 E' F').continuous_at.comp $
(hf.cont 1 hn).continuous_at hs
/-- If a function is `C^n` with `1 ≤ n` around a point, and its derivative at that point is given to
us as `f'`, then `f'` is also a strict derivative. -/
lemma times_cont_diff_at.has_strict_fderiv_at'
{f : E' → F'} {f' : E' →L[𝕂] F'} {x : E'}
{n : with_top ℕ} (hf : times_cont_diff_at 𝕂 n f x) (hf' : has_fderiv_at f f' x) (hn : 1 ≤ n) :
has_strict_fderiv_at f f' x :=
begin
rcases hf 1 hn with ⟨u, H, p, hp⟩,
simp only [nhds_within_univ, mem_univ, insert_eq_of_mem] at H,
have := hp.has_strict_fderiv_at le_rfl H,
rwa hf'.unique this.has_fderiv_at
end
/-- If a function is `C^n` with `1 ≤ n` around a point, and its derivative at that point is given to
us as `f'`, then `f'` is also a strict derivative. -/
lemma times_cont_diff_at.has_strict_deriv_at' {f : 𝕂 → F'} {f' : F'} {x : 𝕂}
{n : with_top ℕ} (hf : times_cont_diff_at 𝕂 n f x) (hf' : has_deriv_at f f' x) (hn : 1 ≤ n) :
has_strict_deriv_at f f' x :=
hf.has_strict_fderiv_at' hf' hn
/-- If a function is `C^n` with `1 ≤ n` around a point, then the derivative of `f` at this point
is also a strict derivative. -/
lemma times_cont_diff_at.has_strict_fderiv_at {f : E' → F'} {x : E'} {n : with_top ℕ}
(hf : times_cont_diff_at 𝕂 n f x) (hn : 1 ≤ n) :
has_strict_fderiv_at f (fderiv 𝕂 f x) x :=
hf.has_strict_fderiv_at' (hf.differentiable_at hn).has_fderiv_at hn
/-- If a function is `C^n` with `1 ≤ n` around a point, then the derivative of `f` at this point
is also a strict derivative. -/
lemma times_cont_diff_at.has_strict_deriv_at {f : 𝕂 → F'} {x : 𝕂} {n : with_top ℕ}
(hf : times_cont_diff_at 𝕂 n f x) (hn : 1 ≤ n) :
has_strict_deriv_at f (deriv f x) x :=
(hf.has_strict_fderiv_at hn).has_strict_deriv_at
/-- If a function is `C^n` with `1 ≤ n`, then the derivative of `f` is also a strict derivative. -/
lemma times_cont_diff.has_strict_fderiv_at
{f : E' → F'} {x : E'} {n : with_top ℕ} (hf : times_cont_diff 𝕂 n f) (hn : 1 ≤ n) :
has_strict_fderiv_at f (fderiv 𝕂 f x) x :=
hf.times_cont_diff_at.has_strict_fderiv_at hn
/-- If a function is `C^n` with `1 ≤ n`, then the derivative of `f` is also a strict derivative. -/
lemma times_cont_diff.has_strict_deriv_at
{f : 𝕂 → F'} {x : 𝕂} {n : with_top ℕ} (hf : times_cont_diff 𝕂 n f) (hn : 1 ≤ n) :
has_strict_deriv_at f (deriv f x) x :=
hf.times_cont_diff_at.has_strict_deriv_at hn
/-- If `f` has a formal Taylor series `p` up to order `1` on `{x} ∪ s`, where `s` is a convex set,
and `∥p x 1∥₊ < K`, then `f` is `K`-Lipschitz in a neighborhood of `x` within `s`. -/
lemma has_ftaylor_series_up_to_on.exists_lipschitz_on_with_of_nnnorm_lt {E F : Type*}
[normed_group E] [normed_space ℝ E] [normed_group F] [normed_space ℝ F] {f : E → F}
{p : E → formal_multilinear_series ℝ E F} {s : set E} {x : E}
(hf : has_ftaylor_series_up_to_on 1 f p (insert x s)) (hs : convex s) (K : ℝ≥0)
(hK : ∥p x 1∥₊ < K) :
∃ t ∈ 𝓝[s] x, lipschitz_on_with K f t :=
begin
set f' := λ y, continuous_multilinear_curry_fin1 ℝ E F (p y 1),
have hder : ∀ y ∈ s, has_fderiv_within_at f (f' y) s y,
from λ y hy, (hf.has_fderiv_within_at le_rfl (subset_insert x s hy)).mono (subset_insert x s),
have hcont : continuous_within_at f' s x,
from (continuous_multilinear_curry_fin1 ℝ E F).continuous_at.comp_continuous_within_at
((hf.cont _ le_rfl _ (mem_insert _ _)).mono (subset_insert x s)),
replace hK : ∥f' x∥₊ < K, by simpa only [linear_isometry_equiv.nnnorm_map],
exact hs.exists_nhds_within_lipschitz_on_with_of_has_fderiv_within_at_of_nnnorm_lt
(eventually_nhds_within_iff.2 $ eventually_of_forall hder) hcont K hK
end
/-- If `f` has a formal Taylor series `p` up to order `1` on `{x} ∪ s`, where `s` is a convex set,
then `f` is Lipschitz in a neighborhood of `x` within `s`. -/
lemma has_ftaylor_series_up_to_on.exists_lipschitz_on_with {E F : Type*}
[normed_group E] [normed_space ℝ E] [normed_group F] [normed_space ℝ F] {f : E → F}
{p : E → formal_multilinear_series ℝ E F} {s : set E} {x : E}
(hf : has_ftaylor_series_up_to_on 1 f p (insert x s)) (hs : convex s) :
∃ K (t ∈ 𝓝[s] x), lipschitz_on_with K f t :=
(no_top _).imp $ hf.exists_lipschitz_on_with_of_nnnorm_lt hs
/-- If `f` is `C^1` within a conves set `s` at `x`, then it is Lipschitz on a neighborhood of `x`
within `s`. -/
lemma times_cont_diff_within_at.exists_lipschitz_on_with {E F : Type*} [normed_group E]
[normed_space ℝ E] [normed_group F] [normed_space ℝ F] {f : E → F} {s : set E}
{x : E} (hf : times_cont_diff_within_at ℝ 1 f s x) (hs : convex s) :
∃ (K : ℝ≥0) (t ∈ 𝓝[s] x), lipschitz_on_with K f t :=
begin
rcases hf 1 le_rfl with ⟨t, hst, p, hp⟩,
rcases metric.mem_nhds_within_iff.mp hst with ⟨ε, ε0, hε⟩,
replace hp : has_ftaylor_series_up_to_on 1 f p (metric.ball x ε ∩ insert x s) := hp.mono hε,
clear hst hε t,
rw [← insert_eq_of_mem (metric.mem_ball_self ε0), ← insert_inter] at hp,
rcases hp.exists_lipschitz_on_with ((convex_ball _ _).inter hs) with ⟨K, t, hst, hft⟩,
rw [inter_comm, ← nhds_within_restrict' _ (metric.ball_mem_nhds _ ε0)] at hst,
exact ⟨K, t, hst, hft⟩
end
/-- If `f` is `C^1` at `x` and `K > ∥fderiv 𝕂 f x∥`, then `f` is `K`-Lipschitz in a neighborhood of
`x`. -/
lemma times_cont_diff_at.exists_lipschitz_on_with_of_nnnorm_lt {f : E' → F'} {x : E'}
(hf : times_cont_diff_at 𝕂 1 f x) (K : ℝ≥0) (hK : ∥fderiv 𝕂 f x∥₊ < K) :
∃ t ∈ 𝓝 x, lipschitz_on_with K f t :=
(hf.has_strict_fderiv_at le_rfl).exists_lipschitz_on_with_of_nnnorm_lt K hK
/-- If `f` is `C^1` at `x`, then `f` is Lipschitz in a neighborhood of `x`. -/
lemma times_cont_diff_at.exists_lipschitz_on_with {f : E' → F'} {x : E'}
(hf : times_cont_diff_at 𝕂 1 f x) :
∃ K (t ∈ 𝓝 x), lipschitz_on_with K f t :=
(hf.has_strict_fderiv_at le_rfl).exists_lipschitz_on_with
end real
section deriv
/-!
### One dimension
All results up to now have been expressed in terms of the general Fréchet derivative `fderiv`. For
maps defined on the field, the one-dimensional derivative `deriv` is often easier to use. In this
paragraph, we reformulate some higher smoothness results in terms of `deriv`.
-/
variables {f₂ : 𝕜 → F} {s₂ : set 𝕜}
open continuous_linear_map (smul_right)
/-- A function is `C^(n + 1)` on a domain with unique derivatives if and only if it is
differentiable there, and its derivative (formulated with `deriv_within`) is `C^n`. -/
theorem times_cont_diff_on_succ_iff_deriv_within {n : ℕ} (hs : unique_diff_on 𝕜 s₂) :
times_cont_diff_on 𝕜 ((n + 1) : ℕ) f₂ s₂ ↔
differentiable_on 𝕜 f₂ s₂ ∧ times_cont_diff_on 𝕜 n (deriv_within f₂ s₂) s₂ :=
begin
rw times_cont_diff_on_succ_iff_fderiv_within hs,
congr' 2,
apply le_antisymm,
{ assume h,
have : deriv_within f₂ s₂ = (λ u : 𝕜 →L[𝕜] F, u 1) ∘ (fderiv_within 𝕜 f₂ s₂),
by { ext x, refl },
simp only [this],
apply times_cont_diff.comp_times_cont_diff_on _ h,
exact (is_bounded_bilinear_map_apply.is_bounded_linear_map_left _).times_cont_diff },
{ assume h,
have : fderiv_within 𝕜 f₂ s₂ = smul_right (1 : 𝕜 →L[𝕜] 𝕜) ∘ deriv_within f₂ s₂,
by { ext x, simp [deriv_within] },
simp only [this],
apply times_cont_diff.comp_times_cont_diff_on _ h,
exact (is_bounded_bilinear_map_smul_right.is_bounded_linear_map_right _).times_cont_diff }
end
/-- A function is `C^(n + 1)` on an open domain if and only if it is
differentiable there, and its derivative (formulated with `deriv`) is `C^n`. -/
theorem times_cont_diff_on_succ_iff_deriv_of_open {n : ℕ} (hs : is_open s₂) :
times_cont_diff_on 𝕜 ((n + 1) : ℕ) f₂ s₂ ↔
differentiable_on 𝕜 f₂ s₂ ∧ times_cont_diff_on 𝕜 n (deriv f₂) s₂ :=
begin
rw times_cont_diff_on_succ_iff_deriv_within hs.unique_diff_on,
congr' 2,
rw ← iff_iff_eq,
apply times_cont_diff_on_congr,
assume x hx,
exact deriv_within_of_open hs hx
end
/-- A function is `C^∞` on a domain with unique derivatives if and only if it is differentiable
there, and its derivative (formulated with `deriv_within`) is `C^∞`. -/
theorem times_cont_diff_on_top_iff_deriv_within (hs : unique_diff_on 𝕜 s₂) :
times_cont_diff_on 𝕜 ∞ f₂ s₂ ↔
differentiable_on 𝕜 f₂ s₂ ∧ times_cont_diff_on 𝕜 ∞ (deriv_within f₂ s₂) s₂ :=
begin
split,
{ assume h,
refine ⟨h.differentiable_on le_top, _⟩,
apply times_cont_diff_on_top.2 (λ n, ((times_cont_diff_on_succ_iff_deriv_within hs).1 _).2),
exact h.of_le le_top },
{ assume h,
refine times_cont_diff_on_top.2 (λ n, _),
have A : (n : with_top ℕ) ≤ ∞ := le_top,
apply ((times_cont_diff_on_succ_iff_deriv_within hs).2 ⟨h.1, h.2.of_le A⟩).of_le,
exact with_top.coe_le_coe.2 (nat.le_succ n) }
end
/-- A function is `C^∞` on an open domain if and only if it is differentiable
there, and its derivative (formulated with `deriv`) is `C^∞`. -/
theorem times_cont_diff_on_top_iff_deriv_of_open (hs : is_open s₂) :
times_cont_diff_on 𝕜 ∞ f₂ s₂ ↔
differentiable_on 𝕜 f₂ s₂ ∧ times_cont_diff_on 𝕜 ∞ (deriv f₂) s₂ :=
begin
rw times_cont_diff_on_top_iff_deriv_within hs.unique_diff_on,
congr' 2,
rw ← iff_iff_eq,
apply times_cont_diff_on_congr,
assume x hx,
exact deriv_within_of_open hs hx
end
lemma times_cont_diff_on.deriv_within {m n : with_top ℕ}
(hf : times_cont_diff_on 𝕜 n f₂ s₂) (hs : unique_diff_on 𝕜 s₂) (hmn : m + 1 ≤ n) :
times_cont_diff_on 𝕜 m (deriv_within f₂ s₂) s₂ :=
begin
cases m,
{ change ∞ + 1 ≤ n at hmn,
have : n = ∞, by simpa using hmn,
rw this at hf,
exact ((times_cont_diff_on_top_iff_deriv_within hs).1 hf).2 },
{ change (m.succ : with_top ℕ) ≤ n at hmn,
exact ((times_cont_diff_on_succ_iff_deriv_within hs).1 (hf.of_le hmn)).2 }
end
lemma times_cont_diff_on.deriv_of_open {m n : with_top ℕ}
(hf : times_cont_diff_on 𝕜 n f₂ s₂) (hs : is_open s₂) (hmn : m + 1 ≤ n) :
times_cont_diff_on 𝕜 m (deriv f₂) s₂ :=
(hf.deriv_within hs.unique_diff_on hmn).congr (λ x hx, (deriv_within_of_open hs hx).symm)
lemma times_cont_diff_on.continuous_on_deriv_within {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f₂ s₂) (hs : unique_diff_on 𝕜 s₂) (hn : 1 ≤ n) :
continuous_on (deriv_within f₂ s₂) s₂ :=
((times_cont_diff_on_succ_iff_deriv_within hs).1 (h.of_le hn)).2.continuous_on
lemma times_cont_diff_on.continuous_on_deriv_of_open {n : with_top ℕ}
(h : times_cont_diff_on 𝕜 n f₂ s₂) (hs : is_open s₂) (hn : 1 ≤ n) :
continuous_on (deriv f₂) s₂ :=
((times_cont_diff_on_succ_iff_deriv_of_open hs).1 (h.of_le hn)).2.continuous_on
/-- A function is `C^(n + 1)` on a domain with unique derivatives if and only if it is
differentiable there, and its derivative is `C^n`. -/
theorem times_cont_diff_succ_iff_deriv {n : ℕ} :
times_cont_diff 𝕜 ((n + 1) : ℕ) f₂ ↔
differentiable 𝕜 f₂ ∧ times_cont_diff 𝕜 n (deriv f₂) :=
by simp only [← times_cont_diff_on_univ, times_cont_diff_on_succ_iff_deriv_of_open, is_open_univ,
differentiable_on_univ]
end deriv
section restrict_scalars
/-!
### Restricting from `ℂ` to `ℝ`, or generally from `𝕜'` to `𝕜`
If a function is `n` times continuously differentiable over `ℂ`, then it is `n` times continuously
differentiable over `ℝ`. In this paragraph, we give variants of this statement, in the general
situation where `ℂ` and `ℝ` are replaced respectively by `𝕜'` and `𝕜` where `𝕜'` is a normed algebra
over `𝕜`.
-/
variables (𝕜) {𝕜' : Type*} [nondiscrete_normed_field 𝕜'] [normed_algebra 𝕜 𝕜']
variables [normed_space 𝕜' E] [is_scalar_tower 𝕜 𝕜' E]
variables [normed_space 𝕜' F] [is_scalar_tower 𝕜 𝕜' F]
variables {p' : E → formal_multilinear_series 𝕜' E F} {n : with_top ℕ}
lemma has_ftaylor_series_up_to_on.restrict_scalars
(h : has_ftaylor_series_up_to_on n f p' s) :
has_ftaylor_series_up_to_on n f (λ x, (p' x).restrict_scalars 𝕜) s :=
{ zero_eq := λ x hx, h.zero_eq x hx,
fderiv_within :=
begin
intros m hm x hx,
convert ((continuous_multilinear_map.restrict_scalars_linear 𝕜).has_fderiv_at)
.comp_has_fderiv_within_at _ ((h.fderiv_within m hm x hx).restrict_scalars 𝕜),
end,
cont := λ m hm, continuous_multilinear_map.continuous_restrict_scalars.comp_continuous_on
(h.cont m hm) }
lemma times_cont_diff_within_at.restrict_scalars (h : times_cont_diff_within_at 𝕜' n f s x) :
times_cont_diff_within_at 𝕜 n f s x :=
begin
intros m hm,
rcases h m hm with ⟨u, u_mem, p', hp'⟩,
exact ⟨u, u_mem, _, hp'.restrict_scalars _⟩
end
lemma times_cont_diff_on.restrict_scalars (h : times_cont_diff_on 𝕜' n f s) :
times_cont_diff_on 𝕜 n f s :=
λ x hx, (h x hx).restrict_scalars _
lemma times_cont_diff_at.restrict_scalars (h : times_cont_diff_at 𝕜' n f x) :
times_cont_diff_at 𝕜 n f x :=
times_cont_diff_within_at_univ.1 $ h.times_cont_diff_within_at.restrict_scalars _
lemma times_cont_diff.restrict_scalars (h : times_cont_diff 𝕜' n f) :
times_cont_diff 𝕜 n f :=
times_cont_diff_iff_times_cont_diff_at.2 $ λ x, h.times_cont_diff_at.restrict_scalars _
end restrict_scalars
|
599a06e06a7fd9bd0894ddfcd878d3a53ff4b2bc | efa51dd2edbbbbd6c34bd0ce436415eb405832e7 | /20170116_POPL/profile/leanfmt_optimized1.lean | 2b8e3eb5d36a1e029c2d44f2e4728bf36f5332bd | [
"Apache-2.0"
] | permissive | leanprover/presentations | dd031a05bcb12c8855676c77e52ed84246bd889a | 3ce2d132d299409f1de269fa8e95afa1333d644e | refs/heads/master | 1,688,703,388,796 | 1,686,838,383,000 | 1,687,465,742,000 | 29,750,158 | 12 | 9 | Apache-2.0 | 1,540,211,670,000 | 1,422,042,683,000 | Lean | UTF-8 | Lean | false | false | 2,684 | lean | open tactic
-- set_option trace.compiler true
namespace fmt
meta def format.concat : list format -> format
| [] := format.nil
| (f :: fs) := f ++ format.concat fs
meta definition mk_local (n : name) (ty : expr) : expr :=
expr.local_const n n binder_info.default ty
meta def binder (n : format) (ty : format) : format :=
"(" ++ n ++ format.space ++ ":" ++ format.space ++ ty ++ ")"
meta def let_binding (n : format) (ty : format) (val : format) : format :=
"x" ++ format.space ++ ":" ++ format.space ++ ":=" ++ val
/- In this version we can fuse 3 loops over the arguments to an
application, giving a ~20% speedup. -/
meta def exp_app (fmt_exp : expr -> format) : list expr → format
| [] := format.nil
| (e :: []) := "(" ++ fmt_exp e ++ ")"
| (e :: es) := "(" ++ fmt_exp e ++ ") " ++ exp_app es
meta def exp : expr → format
| (expr.elet n ty val body) :=
"let" ++ let_binding (to_string n) (exp ty) (exp $ expr.instantiate_var body (mk_local n ty)) ++
format.line ++ "in" ++ format.space ++ exp body
| (expr.app f arg) :=
let fn := expr.get_app_fn (expr.app f arg),
args := expr.get_app_args (expr.app f arg)
in exp fn ++ format.space ++ exp_app exp args
| (expr.const c _) := to_string c
| (expr.local_const n n' bi ty) := to_string n
| (expr.macro _ _ _) := "macro"
| (expr.pi n bi sort ty) :=
"forall" ++ format.space ++ binder (to_string n) (exp sort) ++ "," ++
format.group (format.line ++ format.space ++ exp (expr.instantiate_var ty (mk_local n sort)))
| (expr.lam n bi ty body) :=
"fun" ++ format.space ++ binder (to_string n) (exp ty) ++ "," ++
format.group (format.line ++ exp (expr.instantiate_var body (mk_local n ty)))
| (expr.mvar n ty) := "?" ++ to_string n
| (expr.sort _) := "Type"
| (expr.var i) := "i"
meta def decl : declaration → format
| (declaration.defn n us ty value _ _) :=
"def" ++ format.space ++ to_string n ++ format.space ++ ":" ++ format.space ++ exp ty ++ format.space ++ ":=" ++
format.indent (exp value) 2
| (declaration.ax n us ty) := "axiom" ++ format.space ++ to_string n
| (declaration.cnst n us body _) := "constant" ++ format.space ++ to_string n
| (declaration.thm n us ty body) := "theorem" ++ format.space ++ to_string n
end fmt
/- Turn on the profiler. -/
set_option profiler true
meta def main : tactic unit := do
env ← get_env,
opts ← get_options,
let fs := list.taken 10 $ environment.fold env [] (fun decl decls, fmt.decl decl :: decls) in
monad.mapm (fun f, tactic.trace (format.to_string f opts ++ "\n")) fs,
return ()
/- We can then just run the main function to format all declarations in the environment. -/
run_command main
|
b9f9c40219ff1a8430657b976468537cbaf9a4dc | a4673261e60b025e2c8c825dfa4ab9108246c32e | /stage0/src/Lean/Environment.lean | 470bd977ca423116a8db3dfc2e162283859bd7ad | [
"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 | 28,593 | 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 Std.Data.HashMap
import Lean.Data.SMap
import Lean.Declaration
import Lean.LocalContext
import Lean.Util.Path
import Lean.Util.FindExpr
import Lean.Util.Profile
namespace Lean
/- Opaque environment extension state. -/
constant EnvExtensionStateSpec : PointedType.{0}
def EnvExtensionState : Type := EnvExtensionStateSpec.type
instance : Inhabited EnvExtensionState := ⟨EnvExtensionStateSpec.val⟩
def ModuleIdx := Nat
instance : Inhabited ModuleIdx := inferInstanceAs (Inhabited Nat)
abbrev ConstMap := SMap Name ConstantInfo
structure Import :=
(module : Name)
(runtimeOnly : Bool := false)
instance : ToString Import := ⟨fun imp => toString imp.module ++ if imp.runtimeOnly then " (runtime)" else ""⟩
/--
A compacted region holds multiple Lean objects in a contiguous memory region, which can be read/written to/from disk.
Objects inside the region do not have reference counters and cannot be freed individually. The contents of .olean
files are compacted regions. -/
def CompactedRegion := USize
/-- Free a compacted region and its contents. No live references to the contents may exist at the time of invocation. -/
@[extern 2 "lean_compacted_region_free"]
unsafe constant CompactedRegion.free : CompactedRegion → IO Unit
/- Environment fields that are not used often. -/
structure EnvironmentHeader where
trustLevel : UInt32 := 0
quotInit : Bool := false
mainModule : Name := arbitrary
imports : Array Import := #[] -- direct imports
regions : Array CompactedRegion := #[] -- compacted regions of all imported modules
moduleNames : NameSet := {} -- names of all imported modules
open Std (HashMap)
structure Environment :=
(const2ModIdx : HashMap Name ModuleIdx)
(constants : ConstMap)
(extensions : Array EnvExtensionState)
(header : EnvironmentHeader := {})
namespace Environment
instance : Inhabited Environment :=
⟨{ const2ModIdx := {}, constants := {}, extensions := #[] }⟩
def addAux (env : Environment) (cinfo : ConstantInfo) : Environment :=
{ env with constants := env.constants.insert cinfo.name cinfo }
@[export lean_environment_find]
def find? (env : Environment) (n : Name) : Option ConstantInfo :=
/- It is safe to use `find'` because we never overwrite imported declarations. -/
env.constants.find?' n
def contains (env : Environment) (n : Name) : Bool :=
env.constants.contains n
def imports (env : Environment) : Array Import :=
env.header.imports
def allImportedModuleNames (env : Environment) : NameSet :=
env.header.moduleNames
@[export lean_environment_set_main_module]
def setMainModule (env : Environment) (m : Name) : Environment :=
{ env with header := { env.header with mainModule := m } }
@[export lean_environment_main_module]
def mainModule (env : Environment) : Name :=
env.header.mainModule
@[export lean_environment_mark_quot_init]
private def markQuotInit (env : Environment) : Environment :=
{ env with header := { env.header with quotInit := true } }
@[export lean_environment_quot_init]
private def isQuotInit (env : Environment) : Bool :=
env.header.quotInit
@[export lean_environment_trust_level]
private def getTrustLevel (env : Environment) : UInt32 :=
env.header.trustLevel
def getModuleIdxFor? (env : Environment) (c : Name) : Option ModuleIdx :=
env.const2ModIdx.find? c
def isConstructor (env : Environment) (c : Name) : Bool :=
match env.find? c with
| ConstantInfo.ctorInfo _ => true
| _ => false
end Environment
inductive KernelException :=
| unknownConstant (env : Environment) (name : Name)
| alreadyDeclared (env : Environment) (name : Name)
| declTypeMismatch (env : Environment) (decl : Declaration) (givenType : Expr)
| declHasMVars (env : Environment) (name : Name) (expr : Expr)
| declHasFVars (env : Environment) (name : Name) (expr : Expr)
| funExpected (env : Environment) (lctx : LocalContext) (expr : Expr)
| typeExpected (env : Environment) (lctx : LocalContext) (expr : Expr)
| letTypeMismatch (env : Environment) (lctx : LocalContext) (name : Name) (givenType : Expr) (expectedType : Expr)
| exprTypeMismatch (env : Environment) (lctx : LocalContext) (expr : Expr) (expectedType : Expr)
| appTypeMismatch (env : Environment) (lctx : LocalContext) (app : Expr) (funType : Expr) (argType : Expr)
| invalidProj (env : Environment) (lctx : LocalContext) (proj : Expr)
| other (msg : String)
namespace Environment
/- Type check given declaration and add it to the environment -/
@[extern "lean_add_decl"]
constant addDecl (env : Environment) (decl : @& Declaration) : Except KernelException Environment
/- Compile the given declaration, it assumes the declaration has already been added to the environment using `addDecl`. -/
@[extern "lean_compile_decl"]
constant compileDecl (env : Environment) (opt : @& Options) (decl : @& Declaration) : Except KernelException Environment
def addAndCompile (env : Environment) (opt : Options) (decl : Declaration) : Except KernelException Environment := do
let env ← addDecl env decl
compileDecl env opt decl
end Environment
/- Interface for managing environment extensions. -/
structure EnvExtensionInterface :=
(ext : Type → Type)
(inhabitedExt {σ} : Inhabited σ → Inhabited (ext σ))
(registerExt {σ} (mkInitial : IO σ) : IO (ext σ))
(setState {σ} (e : ext σ) (env : Environment) : σ → Environment)
(modifyState {σ} (e : ext σ) (env : Environment) : (σ → σ) → Environment)
(getState {σ} (e : ext σ) (env : Environment) : σ)
(mkInitialExtStates : IO (Array EnvExtensionState))
instance : Inhabited EnvExtensionInterface := ⟨{
ext := id,
inhabitedExt := id,
registerExt := fun mk => mk,
setState := fun _ env _ => env,
modifyState := fun _ env _ => env,
getState := fun ext _ => ext,
mkInitialExtStates := pure #[]
}⟩
/- Unsafe implementation of `EnvExtensionInterface` -/
namespace EnvExtensionInterfaceUnsafe
structure Ext (σ : Type) :=
(idx : Nat)
(mkInitial : IO σ)
instance {σ} : Inhabited (Ext σ) := ⟨{idx := 0, mkInitial := arbitrary }⟩
private def mkEnvExtensionsRef : IO (IO.Ref (Array (Ext EnvExtensionState))) := IO.mkRef #[]
@[builtinInit mkEnvExtensionsRef] private constant envExtensionsRef : IO.Ref (Array (Ext EnvExtensionState))
unsafe def setState {σ} (ext : Ext σ) (env : Environment) (s : σ) : Environment :=
{ env with extensions := env.extensions.set! ext.idx (unsafeCast s) }
@[inline] unsafe def modifyState {σ : Type} (ext : Ext σ) (env : Environment) (f : σ → σ) : Environment :=
{ env with
extensions := env.extensions.modify ext.idx fun s =>
let s : σ := unsafeCast s;
let s : σ := f s;
unsafeCast s }
unsafe def getState {σ} (ext : Ext σ) (env : Environment) : σ :=
let s : EnvExtensionState := env.extensions.get! ext.idx
unsafeCast s
unsafe def registerExt {σ} (mkInitial : IO σ) : IO (Ext σ) := do
let initializing ← IO.initializing
unless initializing do throw (IO.userError "failed to register environment, extensions can only be registered during initialization")
let exts ← envExtensionsRef.get
let idx := exts.size
let ext : Ext σ := {
idx := idx,
mkInitial := mkInitial,
}
envExtensionsRef.modify fun exts => exts.push (unsafeCast ext)
pure ext
def mkInitialExtStates : IO (Array EnvExtensionState) := do
let exts ← envExtensionsRef.get
exts.mapM fun ext => ext.mkInitial
unsafe def imp : EnvExtensionInterface := {
ext := Ext,
inhabitedExt := fun _ => ⟨arbitrary⟩,
registerExt := registerExt,
setState := setState,
modifyState := modifyState,
getState := getState,
mkInitialExtStates := mkInitialExtStates
}
end EnvExtensionInterfaceUnsafe
@[implementedBy EnvExtensionInterfaceUnsafe.imp]
constant EnvExtensionInterfaceImp : EnvExtensionInterface
def EnvExtension (σ : Type) : Type := EnvExtensionInterfaceImp.ext σ
namespace EnvExtension
instance {σ} [s : Inhabited σ] : Inhabited (EnvExtension σ) := EnvExtensionInterfaceImp.inhabitedExt s
def setState {σ : Type} (ext : EnvExtension σ) (env : Environment) (s : σ) : Environment := EnvExtensionInterfaceImp.setState ext env s
def modifyState {σ : Type} (ext : EnvExtension σ) (env : Environment) (f : σ → σ) : Environment := EnvExtensionInterfaceImp.modifyState ext env f
def getState {σ : Type} (ext : EnvExtension σ) (env : Environment) : σ := EnvExtensionInterfaceImp.getState ext env
end EnvExtension
/- Environment extensions can only be registered during initialization.
Reasons:
1- Our implementation assumes the number of extensions does not change after an environment object is created.
2- We do not use any synchronization primitive to access `envExtensionsRef`. -/
def registerEnvExtension {σ : Type} (mkInitial : IO σ) : IO (EnvExtension σ) := EnvExtensionInterfaceImp.registerExt mkInitial
private def mkInitialExtensionStates : IO (Array EnvExtensionState) := EnvExtensionInterfaceImp.mkInitialExtStates
@[export lean_mk_empty_environment]
def mkEmptyEnvironment (trustLevel : UInt32 := 0) : IO Environment := do
let initializing ← IO.initializing
if initializing then throw (IO.userError "environment objects cannot be created during initialization")
let exts ← mkInitialExtensionStates
pure {
const2ModIdx := {},
constants := {},
header := { trustLevel := trustLevel },
extensions := exts
}
structure PersistentEnvExtensionState (α : Type) (σ : Type) :=
(importedEntries : Array (Array α)) -- entries per imported module
(state : σ)
structure ImportM.Context :=
(env : Environment)
(opts : Options)
abbrev ImportM := ReaderT Lean.ImportM.Context IO
/- An environment extension with support for storing/retrieving entries from a .olean file.
- α is the type of the entries that are stored in .olean files.
- β is the type of values used to update the state.
- σ is the actual state.
Remark: for most extensions α and β coincide.
Note that `addEntryFn` is not in `IO`. This is intentional, and allows us to write simple functions such as
```
def addAlias (env : Environment) (a : Name) (e : Name) : Environment :=
aliasExtension.addEntry env (a, e)
```
without using `IO`. We have many functions like `addAlias`.
`α` and ‵β` do not coincide for extensions where the data used to update the state contains, for example,
closures which we currently cannot store in files. -/
structure PersistentEnvExtension (α : Type) (β : Type) (σ : Type) :=
(toEnvExtension : EnvExtension (PersistentEnvExtensionState α σ))
(name : Name)
(addImportedFn : Array (Array α) → ImportM σ)
(addEntryFn : σ → β → σ)
(exportEntriesFn : σ → Array α)
(statsFn : σ → Format)
/- Opaque persistent environment extension entry. -/
constant EnvExtensionEntrySpec : PointedType.{0}
def EnvExtensionEntry : Type := EnvExtensionEntrySpec.type
instance : Inhabited EnvExtensionEntry := ⟨EnvExtensionEntrySpec.val⟩
instance {α σ} [Inhabited σ] : Inhabited (PersistentEnvExtensionState α σ) :=
⟨{importedEntries := #[], state := arbitrary }⟩
instance {α β σ} [Inhabited σ] : Inhabited (PersistentEnvExtension α β σ) := ⟨{
toEnvExtension := arbitrary,
name := arbitrary,
addImportedFn := fun _ => arbitrary,
addEntryFn := fun s _ => s,
exportEntriesFn := fun _ => #[],
statsFn := fun _ => Format.nil
}⟩
namespace PersistentEnvExtension
def getModuleEntries {α β σ : Type} (ext : PersistentEnvExtension α β σ) (env : Environment) (m : ModuleIdx) : Array α :=
(ext.toEnvExtension.getState env).importedEntries.get! m
def addEntry {α β σ : Type} (ext : PersistentEnvExtension α β σ) (env : Environment) (b : β) : Environment :=
ext.toEnvExtension.modifyState env fun s =>
let state := ext.addEntryFn s.state b;
{ s with state := state }
def getState {α β σ : Type} (ext : PersistentEnvExtension α β σ) (env : Environment) : σ :=
(ext.toEnvExtension.getState env).state
def setState {α β σ : Type} (ext : PersistentEnvExtension α β σ) (env : Environment) (s : σ) : Environment :=
ext.toEnvExtension.modifyState env $ fun ps => { ps with state := s }
def modifyState {α β σ : Type} (ext : PersistentEnvExtension α β σ) (env : Environment) (f : σ → σ) : Environment :=
ext.toEnvExtension.modifyState env $ fun ps => { ps with state := f (ps.state) }
end PersistentEnvExtension
builtin_initialize persistentEnvExtensionsRef : IO.Ref (Array (PersistentEnvExtension EnvExtensionEntry EnvExtensionEntry EnvExtensionState)) ← IO.mkRef #[]
structure PersistentEnvExtensionDescr (α β σ : Type) :=
(name : Name)
(mkInitial : IO σ)
(addImportedFn : Array (Array α) → ImportM σ)
(addEntryFn : σ → β → σ)
(exportEntriesFn : σ → Array α)
(statsFn : σ → Format := fun _ => Format.nil)
unsafe def registerPersistentEnvExtensionUnsafe {α β σ : Type} [Inhabited σ] (descr : PersistentEnvExtensionDescr α β σ) : IO (PersistentEnvExtension α β σ) := do
let pExts ← persistentEnvExtensionsRef.get
if pExts.any (fun ext => ext.name == descr.name) then throw (IO.userError s!"invalid environment extension, '{descr.name}' has already been used")
let ext ← registerEnvExtension do
let initial ← descr.mkInitial
let s : PersistentEnvExtensionState α σ := {
importedEntries := #[],
state := initial
}
pure s
let pExt : PersistentEnvExtension α β σ := {
toEnvExtension := ext,
name := descr.name,
addImportedFn := descr.addImportedFn,
addEntryFn := descr.addEntryFn,
exportEntriesFn := descr.exportEntriesFn,
statsFn := descr.statsFn
}
persistentEnvExtensionsRef.modify fun pExts => pExts.push (unsafeCast pExt)
pure pExt
@[implementedBy registerPersistentEnvExtensionUnsafe]
constant registerPersistentEnvExtension {α β σ : Type} [Inhabited σ] (descr : PersistentEnvExtensionDescr α β σ) : IO (PersistentEnvExtension α β σ)
/- Simple PersistentEnvExtension that implements exportEntriesFn using a list of entries. -/
def SimplePersistentEnvExtension (α σ : Type) := PersistentEnvExtension α α (List α × σ)
@[specialize] def mkStateFromImportedEntries {α σ : Type} (addEntryFn : σ → α → σ) (initState : σ) (as : Array (Array α)) : σ :=
as.foldl (fun r es => es.foldl (fun r e => addEntryFn r e) r) initState
structure SimplePersistentEnvExtensionDescr (α σ : Type) :=
(name : Name)
(addEntryFn : σ → α → σ)
(addImportedFn : Array (Array α) → σ)
(toArrayFn : List α → Array α := fun es => es.toArray)
def registerSimplePersistentEnvExtension {α σ : Type} [Inhabited σ] (descr : SimplePersistentEnvExtensionDescr α σ) : IO (SimplePersistentEnvExtension α σ) :=
registerPersistentEnvExtension {
name := descr.name,
mkInitial := pure ([], descr.addImportedFn #[]),
addImportedFn := fun as => pure ([], descr.addImportedFn as),
addEntryFn := fun s e => match s with
| (entries, s) => (e::entries, descr.addEntryFn s e),
exportEntriesFn := fun s => descr.toArrayFn s.1.reverse,
statsFn := fun s => format "number of local entries: " ++ format s.1.length
}
namespace SimplePersistentEnvExtension
instance {α σ : Type} [Inhabited σ] : Inhabited (SimplePersistentEnvExtension α σ) :=
inferInstanceAs (Inhabited (PersistentEnvExtension α α (List α × σ)))
def getEntries {α σ : Type} (ext : SimplePersistentEnvExtension α σ) (env : Environment) : List α :=
(PersistentEnvExtension.getState ext env).1
def getState {α σ : Type} (ext : SimplePersistentEnvExtension α σ) (env : Environment) : σ :=
(PersistentEnvExtension.getState ext env).2
def setState {α σ : Type} (ext : SimplePersistentEnvExtension α σ) (env : Environment) (s : σ) : Environment :=
PersistentEnvExtension.modifyState ext env (fun ⟨entries, _⟩ => (entries, s))
def modifyState {α σ : Type} (ext : SimplePersistentEnvExtension α σ) (env : Environment) (f : σ → σ) : Environment :=
PersistentEnvExtension.modifyState ext env (fun ⟨entries, s⟩ => (entries, f s))
end SimplePersistentEnvExtension
/-- Environment extension for tagging declarations.
Declarations must only be tagged in the module where they were declared. -/
def TagDeclarationExtension := SimplePersistentEnvExtension Name NameSet
def mkTagDeclarationExtension (name : Name) : IO TagDeclarationExtension :=
registerSimplePersistentEnvExtension {
name := name,
addImportedFn := fun as => {},
addEntryFn := fun s n => s.insert n,
toArrayFn := fun es => es.toArray.qsort Name.quickLt
}
namespace TagDeclarationExtension
instance : Inhabited TagDeclarationExtension :=
inferInstanceAs (Inhabited (SimplePersistentEnvExtension Name NameSet))
def tag (ext : TagDeclarationExtension) (env : Environment) (n : Name) : Environment :=
ext.addEntry env n
def isTagged (ext : TagDeclarationExtension) (env : Environment) (n : Name) : Bool :=
match env.getModuleIdxFor? n with
| some modIdx => (ext.getModuleEntries env modIdx).binSearchContains n Name.quickLt
| none => (ext.getState env).contains n
end TagDeclarationExtension
/- Content of a .olean file.
We use `compact.cpp` to generate the image of this object in disk. -/
structure ModuleData :=
(imports : Array Import)
(constants : Array ConstantInfo)
(entries : Array (Name × Array EnvExtensionEntry))
instance : Inhabited ModuleData :=
⟨{imports := arbitrary, constants := arbitrary, entries := arbitrary }⟩
@[extern 3 "lean_save_module_data"]
constant saveModuleData (fname : @& String) (m : ModuleData) : IO Unit
@[extern 2 "lean_read_module_data"]
constant readModuleData (fname : @& String) : IO (ModuleData × CompactedRegion)
/--
Free compacted regions of imports. No live references to imported objects may exist at the time of invocation; in
particular, `env` should be the last reference to any `Environment` derived from these imports. -/
@[noinline, export lean_environment_free_regions]
unsafe def Environment.freeRegions (env : Environment) : IO Unit :=
/-
NOTE: This assumes `env` is not inferred as a borrowed parameter, and is freed after extracting the `header` field.
Otherwise, we would encounter undefined behavior when the constant map in `env`, which may reference objects in
compacted regions, is freed after the regions.
In the currently produced IR, we indeed see:
```
def Lean.Environment.freeRegions (x_1 : obj) (x_2 : obj) : obj :=
let x_3 : obj := proj[3] x_1;
inc x_3;
dec x_1;
...
```
TODO: statically check for this. -/
env.header.regions.forM CompactedRegion.free
def mkModuleData (env : Environment) : IO ModuleData := do
let pExts ← persistentEnvExtensionsRef.get
let entries : Array (Name × Array EnvExtensionEntry) := pExts.size.fold
(fun i result =>
let state := (pExts.get! i).getState env
let exportEntriesFn := (pExts.get! i).exportEntriesFn
let extName := (pExts.get! i).name
result.push (extName, exportEntriesFn state))
#[]
pure {
imports := env.header.imports,
constants := env.constants.foldStage2 (fun cs _ c => cs.push c) #[],
entries := entries
}
@[export lean_write_module]
def writeModule (env : Environment) (fname : String) : IO Unit := do
let modData ← mkModuleData env; saveModuleData fname modData
partial def importModulesAux : List Import → (NameSet × Array ModuleData × Array CompactedRegion) → IO (NameSet × Array ModuleData × Array CompactedRegion)
| [], r => pure r
| i::is, (s, mods, regions) =>
if i.runtimeOnly || s.contains i.module then
importModulesAux is (s, mods, regions)
else do
let s := s.insert i.module
let mFile ← findOLean i.module
unless (← IO.fileExists mFile) do
throw $ IO.userError s!"object file '{mFile}' of module {i.module} does not exist"
let (mod, region) ← readModuleData mFile
let (s, mods, regions) ← importModulesAux mod.imports.toList (s, mods, regions)
let mods := mods.push mod
let regions := regions.push region
importModulesAux is (s, mods, regions)
private partial def getEntriesFor (mod : ModuleData) (extId : Name) (i : Nat) : Array EnvExtensionEntry :=
if i < mod.entries.size then
let curr := mod.entries.get! i;
if curr.1 == extId then curr.2 else getEntriesFor mod extId (i+1)
else
#[]
private def setImportedEntries (env : Environment) (mods : Array ModuleData) : IO Environment := do
let mut env := env
let pExtDescrs ← persistentEnvExtensionsRef.get
for mod in mods do
for extDescr in pExtDescrs do
let entries := getEntriesFor mod extDescr.name 0
env ← extDescr.toEnvExtension.modifyState env fun s => { s with importedEntries := s.importedEntries.push entries }
return env
private def finalizePersistentExtensions (env : Environment) (opts : Options) : IO Environment := do
let mut env := env
let pExtDescrs ← persistentEnvExtensionsRef.get
for extDescr in pExtDescrs do
let s := extDescr.toEnvExtension.getState env
let newState ← extDescr.addImportedFn s.importedEntries { env := env, opts := opts }
env ← extDescr.toEnvExtension.setState env { s with state := newState }
return env
@[export lean_import_modules]
def importModules (imports : List Import) (opts : Options) (trustLevel : UInt32 := 0) : IO Environment := profileitIO "import" ⟨0, 0⟩ do
let (moduleNames, mods, regions) ← importModulesAux imports ({}, #[], #[])
let mut modIdx : Nat := 0
let mut const2ModIdx : HashMap Name ModuleIdx := {}
let mut constants : ConstMap := SMap.empty
for mod in mods do
for cinfo in mod.constants do
const2ModIdx := const2ModIdx.insert cinfo.name modIdx
if constants.contains cinfo.name then throw (IO.userError s!"import failed, environment already contains '{cinfo.name}'")
constants := constants.insert cinfo.name cinfo
modIdx := modIdx + 1
constants := constants.switch
let exts ← mkInitialExtensionStates
let env : Environment := {
const2ModIdx := const2ModIdx,
constants := constants,
extensions := exts,
header := {
quotInit := !imports.isEmpty, -- We assume `core.lean` initializes quotient module
trustLevel := trustLevel,
imports := imports.toArray,
regions := regions,
moduleNames := moduleNames
}
}
let env ← setImportedEntries env mods
let env ← finalizePersistentExtensions env opts
pure env
/--
Create environment object from imports and free compacted regions after calling `act`. No live references to the
environment object or imported objects may exist after `act` finishes. -/
unsafe def withImportModules {α : Type} (imports : List Import) (opts : Options) (trustLevel : UInt32 := 0) (x : Environment → IO α) : IO α := do
let env ← importModules imports opts trustLevel
try x env finally env.freeRegions
builtin_initialize namespacesExt : SimplePersistentEnvExtension Name NameSet ←
registerSimplePersistentEnvExtension {
name := `namespaces,
addImportedFn := fun as => mkStateFromImportedEntries NameSet.insert {} as,
addEntryFn := fun s n => s.insert n
}
namespace Environment
def registerNamespace (env : Environment) (n : Name) : Environment :=
if (namespacesExt.getState env).contains n then env else namespacesExt.addEntry env n
def isNamespace (env : Environment) (n : Name) : Bool :=
(namespacesExt.getState env).contains n
def getNamespaceSet (env : Environment) : NameSet :=
namespacesExt.getState env
private def isNamespaceName : Name → Bool
| Name.str Name.anonymous _ _ => true
| Name.str p _ _ => isNamespaceName p
| _ => false
private def registerNamePrefixes : Environment → Name → Environment
| env, Name.str p _ _ => if isNamespaceName p then registerNamePrefixes (registerNamespace env p) p else env
| env, _ => env
@[export lean_environment_add]
def add (env : Environment) (cinfo : ConstantInfo) : Environment :=
let env := registerNamePrefixes env cinfo.name
env.addAux cinfo
@[export lean_display_stats]
def displayStats (env : Environment) : IO Unit := do
let pExtDescrs ← persistentEnvExtensionsRef.get
let numModules := ((pExtDescrs.get! 0).toEnvExtension.getState env).importedEntries.size;
IO.println ("direct imports: " ++ toString env.header.imports);
IO.println ("number of imported modules: " ++ toString numModules);
IO.println ("number of consts: " ++ toString env.constants.size);
IO.println ("number of imported consts: " ++ toString env.constants.stageSizes.1);
IO.println ("number of local consts: " ++ toString env.constants.stageSizes.2);
IO.println ("number of buckets for imported consts: " ++ toString env.constants.numBuckets);
IO.println ("trust level: " ++ toString env.header.trustLevel);
IO.println ("number of extensions: " ++ toString env.extensions.size);
pExtDescrs.forM $ fun extDescr => do
IO.println ("extension '" ++ toString extDescr.name ++ "'")
let s := extDescr.toEnvExtension.getState env
let fmt := extDescr.statsFn s.state
unless fmt.isNil do IO.println (" " ++ toString (Format.nest 2 (extDescr.statsFn s.state)))
IO.println (" number of imported entries: " ++ toString (s.importedEntries.foldl (fun sum es => sum + es.size) 0))
@[extern "lean_eval_const"]
unsafe constant evalConst (α) (env : @& Environment) (opts : @& Options) (constName : @& Name) : Except String α
private def throwUnexpectedType {α} (typeName : Name) (constName : Name) : ExceptT String Id α :=
throw ("unexpected type at '" ++ toString constName ++ "', `" ++ toString typeName ++ "` expected")
/-- Like `evalConst`, but first check that `constName` indeed is a declaration of type `typeName`.
This function is still unsafe because it cannot guarantee that `typeName` is in fact the name of the type `α`. -/
unsafe def evalConstCheck (α) (env : Environment) (opts : Options) (typeName : Name) (constName : Name) : ExceptT String Id α :=
match env.find? constName with
| none => throw ("unknow constant '" ++ toString constName ++ "'")
| some info =>
match info.type with
| Expr.const c _ _ =>
if c != typeName then throwUnexpectedType typeName constName
else env.evalConst α opts constName
| _ => throwUnexpectedType typeName constName
def hasUnsafe (env : Environment) (e : Expr) : Bool :=
let c? := e.find? $ fun e => match e with
| Expr.const c _ _ =>
match env.find? c with
| some cinfo => cinfo.isUnsafe
| none => false
| _ => false;
c?.isSome
end Environment
namespace Kernel
/- Kernel API -/
/--
Kernel isDefEq predicate. We use it mainly for debugging purposes.
Recall that the Kernel type checker does not support metavariables.
When implementing automation, consider using the `MetaM` methods. -/
@[extern "lean_kernel_is_def_eq"]
constant isDefEq (env : Environment) (lctx : LocalContext) (a b : Expr) : Bool
/--
Kernel WHNF function. We use it mainly for debugging purposes.
Recall that the Kernel type checker does not support metavariables.
When implementing automation, consider using the `MetaM` methods. -/
@[extern "lean_kernel_whnf"]
constant whnf (env : Environment) (lctx : LocalContext) (a : Expr) : Expr
end Kernel
class MonadEnv (m : Type → Type) :=
(getEnv : m Environment)
(modifyEnv : (Environment → Environment) → m Unit)
export MonadEnv (getEnv modifyEnv)
instance (m n) [MonadEnv m] [MonadLift m n] : MonadEnv n := {
getEnv := liftM (getEnv : m Environment),
modifyEnv := fun f => liftM (modifyEnv f : m Unit)
}
end Lean
|
ec65ef812ee8c7622a03ea9d12875144b42691b6 | d406927ab5617694ec9ea7001f101b7c9e3d9702 | /src/order/sup_indep.lean | 70c982f5ccad450165ce96287f20593663bd8962 | [
"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 | 14,363 | lean | /-
Copyright (c) 2021 Aaron Anderson, Yaël Dillies. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Aaron Anderson, Kevin Buzzard, Yaël Dillies, Eric Wieser
-/
import data.finset.pairwise
import data.finset.powerset
import data.fintype.basic
/-!
# Supremum independence
In this file, we define supremum independence of indexed sets. An indexed family `f : ι → α` is
sup-independent if, for all `a`, `f a` and the supremum of the rest are disjoint.
## Main definitions
* `finset.sup_indep s f`: a family of elements `f` are supremum independent on the finite set `s`.
* `complete_lattice.set_independent s`: a set of elements are supremum independent.
* `complete_lattice.independent f`: a family of elements are supremum independent.
## Main statements
* In a distributive lattice, supremum independence is equivalent to pairwise disjointness:
* `finset.sup_indep_iff_pairwise_disjoint`
* `complete_lattice.set_independent_iff_pairwise_disjoint`
* `complete_lattice.independent_iff_pairwise_disjoint`
* Otherwise, supremum independence is stronger than pairwise disjointness:
* `finset.sup_indep.pairwise_disjoint`
* `complete_lattice.set_independent.pairwise_disjoint`
* `complete_lattice.independent.pairwise_disjoint`
## Implementation notes
For the finite version, we avoid the "obvious" definition
`∀ i ∈ s, disjoint (f i) ((s.erase i).sup f)` because `erase` would require decidable equality on
`ι`.
-/
variables {α β ι ι' : Type*}
/-! ### On lattices with a bottom element, via `finset.sup` -/
namespace finset
section lattice
variables [lattice α] [order_bot α]
/-- Supremum independence of finite sets. We avoid the "obvious" definition using `s.erase i`
because `erase` would require decidable equality on `ι`. -/
def sup_indep (s : finset ι) (f : ι → α) : Prop :=
∀ ⦃t⦄, t ⊆ s → ∀ ⦃i⦄, i ∈ s → i ∉ t → disjoint (f i) (t.sup f)
variables {s t : finset ι} {f : ι → α} {i : ι}
instance [decidable_eq ι] [decidable_eq α] : decidable (sup_indep s f) :=
begin
apply @finset.decidable_forall_of_decidable_subsets _ _ _ _,
intros t ht,
apply @finset.decidable_dforall_finset _ _ _ _,
exact λ i hi, @implies.decidable _ _ _ (decidable_of_iff' (_ = ⊥) disjoint_iff),
end
lemma sup_indep.subset (ht : t.sup_indep f) (h : s ⊆ t) : s.sup_indep f :=
λ u hu i hi, ht (hu.trans h) (h hi)
lemma sup_indep_empty (f : ι → α) : (∅ : finset ι).sup_indep f := λ _ _ a ha, ha.elim
lemma sup_indep_singleton (i : ι) (f : ι → α) : ({i} : finset ι).sup_indep f :=
λ s hs j hji hj, begin
rw [eq_empty_of_ssubset_singleton ⟨hs, λ h, hj (h hji)⟩, sup_empty],
exact disjoint_bot_right,
end
lemma sup_indep.pairwise_disjoint (hs : s.sup_indep f) : (s : set ι).pairwise_disjoint f :=
λ a ha b hb hab, sup_singleton.subst $ hs (singleton_subset_iff.2 hb) ha $ not_mem_singleton.2 hab
/-- The RHS looks like the definition of `complete_lattice.independent`. -/
lemma sup_indep_iff_disjoint_erase [decidable_eq ι] :
s.sup_indep f ↔ ∀ i ∈ s, disjoint (f i) ((s.erase i).sup f) :=
⟨λ hs i hi, hs (erase_subset _ _) hi (not_mem_erase _ _), λ hs t ht i hi hit,
(hs i hi).mono_right (sup_mono $ λ j hj, mem_erase.2 ⟨ne_of_mem_of_not_mem hj hit, ht hj⟩)⟩
@[simp] lemma sup_indep_pair [decidable_eq ι] {i j : ι} (hij : i ≠ j) :
({i, j} : finset ι).sup_indep f ↔ disjoint (f i) (f j) :=
⟨λ h, h.pairwise_disjoint (by simp) (by simp) hij, λ h, begin
rw sup_indep_iff_disjoint_erase,
intros k hk,
rw [finset.mem_insert, finset.mem_singleton] at hk,
obtain rfl | rfl := hk,
{ convert h using 1,
rw [finset.erase_insert, finset.sup_singleton],
simpa using hij },
{ convert h.symm using 1,
have : ({i, k} : finset ι).erase k = {i},
{ ext,
rw [mem_erase, mem_insert, mem_singleton, mem_singleton, and_or_distrib_left,
ne.def, not_and_self, or_false, and_iff_right_of_imp],
rintro rfl,
exact hij },
rw [this, finset.sup_singleton] }
end⟩
lemma sup_indep_univ_bool (f : bool → α) :
(finset.univ : finset bool).sup_indep f ↔ disjoint (f ff) (f tt) :=
begin
have : tt ≠ ff := by simp only [ne.def, not_false_iff],
exact (sup_indep_pair this).trans disjoint.comm,
end
@[simp] lemma sup_indep_univ_fin_two (f : fin 2 → α) :
(finset.univ : finset (fin 2)).sup_indep f ↔ disjoint (f 0) (f 1) :=
begin
have : (0 : fin 2) ≠ 1 := by simp,
exact sup_indep_pair this,
end
lemma sup_indep.attach (hs : s.sup_indep f) : s.attach.sup_indep (f ∘ subtype.val) :=
begin
intros t ht i _ hi,
classical,
rw ←finset.sup_image,
refine hs (image_subset_iff.2 $ λ (j : {x // x ∈ s}) _, j.2) i.2 (λ hi', hi _),
rw mem_image at hi',
obtain ⟨j, hj, hji⟩ := hi',
rwa subtype.ext hji at hj,
end
end lattice
section distrib_lattice
variables [distrib_lattice α] [order_bot α] {s : finset ι} {f : ι → α}
lemma sup_indep_iff_pairwise_disjoint : s.sup_indep f ↔ (s : set ι).pairwise_disjoint f :=
⟨sup_indep.pairwise_disjoint, λ hs t ht i hi hit,
disjoint_sup_right.2 $ λ j hj, hs hi (ht hj) (ne_of_mem_of_not_mem hj hit).symm⟩
alias sup_indep_iff_pairwise_disjoint ↔ sup_indep.pairwise_disjoint
_root_.set.pairwise_disjoint.sup_indep
/-- Bind operation for `sup_indep`. -/
lemma sup_indep.sup [decidable_eq ι] {s : finset ι'} {g : ι' → finset ι} {f : ι → α}
(hs : s.sup_indep (λ i, (g i).sup f)) (hg : ∀ i' ∈ s, (g i').sup_indep f) :
(s.sup g).sup_indep f :=
begin
simp_rw sup_indep_iff_pairwise_disjoint at ⊢ hs hg,
rw [sup_eq_bUnion, coe_bUnion],
exact hs.bUnion_finset hg,
end
/-- Bind operation for `sup_indep`. -/
lemma sup_indep.bUnion [decidable_eq ι] {s : finset ι'} {g : ι' → finset ι} {f : ι → α}
(hs : s.sup_indep (λ i, (g i).sup f)) (hg : ∀ i' ∈ s, (g i').sup_indep f) :
(s.bUnion g).sup_indep f :=
by { rw ←sup_eq_bUnion, exact hs.sup hg }
end distrib_lattice
end finset
/-! ### On complete lattices via `has_Sup.Sup` -/
namespace complete_lattice
variables [complete_lattice α]
open set function
/-- An independent set of elements in a complete lattice is one in which every element is disjoint
from the `Sup` of the rest. -/
def set_independent (s : set α) : Prop := ∀ ⦃a⦄, a ∈ s → disjoint a (Sup (s \ {a}))
variables {s : set α} (hs : set_independent s)
@[simp]
lemma set_independent_empty : set_independent (∅ : set α) :=
λ x hx, (set.not_mem_empty x hx).elim
theorem set_independent.mono {t : set α} (hst : t ⊆ s) :
set_independent t :=
λ a ha, (hs (hst ha)).mono_right (Sup_le_Sup (diff_subset_diff_left hst))
/-- If the elements of a set are independent, then any pair within that set is disjoint. -/
lemma set_independent.pairwise_disjoint : s.pairwise_disjoint id :=
λ x hx y hy h, disjoint_Sup_right (hs hx) ((mem_diff y).mpr ⟨hy, h.symm⟩)
lemma set_independent_pair {a b : α} (hab : a ≠ b) :
set_independent ({a, b} : set α) ↔ disjoint a b :=
begin
split,
{ intro h,
exact h.pairwise_disjoint (mem_insert _ _) (mem_insert_of_mem _ (mem_singleton _)) hab, },
{ rintros h c ((rfl : c = a) | (rfl : c = b)),
{ convert h using 1,
simp [hab, Sup_singleton] },
{ convert h.symm using 1,
simp [hab, Sup_singleton] }, },
end
include hs
/-- If the elements of a set are independent, then any element is disjoint from the `Sup` of some
subset of the rest. -/
lemma set_independent.disjoint_Sup {x : α} {y : set α} (hx : x ∈ s) (hy : y ⊆ s) (hxy : x ∉ y) :
disjoint x (Sup y) :=
begin
have := (hs.mono $ insert_subset.mpr ⟨hx, hy⟩) (mem_insert x _),
rw [insert_diff_of_mem _ (mem_singleton _), diff_singleton_eq_self hxy] at this,
exact this,
end
omit hs
/-- An independent indexed family of elements in a complete lattice is one in which every element
is disjoint from the `supr` of the rest.
Example: an indexed family of non-zero elements in a
vector space is linearly independent iff the indexed family of subspaces they generate is
independent in this sense.
Example: an indexed family of submodules of a module is independent in this sense if
and only the natural map from the direct sum of the submodules to the module is injective. -/
def independent {ι : Sort*} {α : Type*} [complete_lattice α] (t : ι → α) : Prop :=
∀ i : ι, disjoint (t i) (⨆ (j ≠ i), t j)
lemma set_independent_iff {α : Type*} [complete_lattice α] (s : set α) :
set_independent s ↔ independent (coe : s → α) :=
begin
simp_rw [independent, set_independent, set_coe.forall, Sup_eq_supr],
refine forall₂_congr (λ a ha, _),
congr' 2,
convert supr_subtype.symm,
simp [supr_and],
end
variables {t : ι → α} (ht : independent t)
theorem independent_def : independent t ↔ ∀ i : ι, disjoint (t i) (⨆ (j ≠ i), t j) :=
iff.rfl
theorem independent_def' :
independent t ↔ ∀ i, disjoint (t i) (Sup (t '' {j | j ≠ i})) :=
by {simp_rw Sup_image, refl}
theorem independent_def'' :
independent t ↔ ∀ i, disjoint (t i) (Sup {a | ∃ j ≠ i, t j = a}) :=
by {rw independent_def', tidy}
@[simp]
lemma independent_empty (t : empty → α) : independent t.
@[simp]
lemma independent_pempty (t : pempty → α) : independent t.
/-- If the elements of a set are independent, then any pair within that set is disjoint. -/
lemma independent.pairwise_disjoint : pairwise (disjoint on t) :=
λ x y h, disjoint_Sup_right (ht x) ⟨y, supr_pos h.symm⟩
lemma independent.mono
{s t : ι → α} (hs : independent s) (hst : t ≤ s) :
independent t :=
λ i, (hs i).mono (hst i) $ supr₂_mono $ λ j _, hst j
/-- Composing an independent indexed family with an injective function on the index results in
another indepedendent indexed family. -/
lemma independent.comp {ι ι' : Sort*}
{t : ι → α} {f : ι' → ι} (ht : independent t) (hf : injective f) :
independent (t ∘ f) :=
λ i, (ht (f i)).mono_right $ begin
refine (supr_mono $ λ i, _).trans (supr_comp_le _ f),
exact supr_const_mono hf.ne,
end
lemma independent.comp' {ι ι' : Sort*}
{t : ι → α} {f : ι' → ι} (ht : independent $ t ∘ f) (hf : surjective f) :
independent t :=
begin
intros i,
obtain ⟨i', rfl⟩ := hf i,
rw ← hf.supr_comp,
exact (ht i').mono_right (bsupr_mono $ λ j' hij, mt (congr_arg f) hij),
end
lemma independent.set_independent_range (ht : independent t) :
set_independent $ range t :=
begin
rw set_independent_iff,
rw ← coe_comp_range_factorization t at ht,
exact ht.comp' surjective_onto_range,
end
lemma independent.injective (ht : independent t) (h_ne_bot : ∀ i, t i ≠ ⊥) : injective t :=
begin
intros i j h,
by_contra' contra,
apply h_ne_bot j,
suffices : t j ≤ ⨆ k (hk : k ≠ i), t k,
{ replace ht := (ht i).mono_right this,
rwa [h, disjoint_self] at ht, },
replace contra : j ≠ i, { exact ne.symm contra, },
exact le_supr₂ j contra,
end
lemma independent_pair {i j : ι} (hij : i ≠ j) (huniv : ∀ k, k = i ∨ k = j):
independent t ↔ disjoint (t i) (t j) :=
begin
split,
{ exact λ h, h.pairwise_disjoint hij },
{ rintros h k,
obtain rfl | rfl := huniv k,
{ refine h.mono_right (supr_le $ λ i, supr_le $ λ hi, eq.le _),
rw (huniv i).resolve_left hi },
{ refine h.symm.mono_right (supr_le $ λ j, supr_le $ λ hj, eq.le _),
rw (huniv j).resolve_right hj } },
end
/-- Composing an indepedent indexed family with an order isomorphism on the elements results in
another indepedendent indexed family. -/
lemma independent.map_order_iso {ι : Sort*} {α β : Type*}
[complete_lattice α] [complete_lattice β] (f : α ≃o β) {a : ι → α} (ha : independent a) :
independent (f ∘ a) :=
λ i, ((ha i).map_order_iso f).mono_right (f.monotone.le_map_supr₂ _)
@[simp] lemma independent_map_order_iso_iff {ι : Sort*} {α β : Type*}
[complete_lattice α] [complete_lattice β] (f : α ≃o β) {a : ι → α} :
independent (f ∘ a) ↔ independent a :=
⟨ λ h, have hf : f.symm ∘ f ∘ a = a := congr_arg (∘ a) f.left_inv.comp_eq_id,
hf ▸ h.map_order_iso f.symm,
λ h, h.map_order_iso f⟩
/-- If the elements of a set are independent, then any element is disjoint from the `supr` of some
subset of the rest. -/
lemma independent.disjoint_bsupr {ι : Type*} {α : Type*} [complete_lattice α]
{t : ι → α} (ht : independent t) {x : ι} {y : set ι} (hx : x ∉ y) :
disjoint (t x) (⨆ i ∈ y, t i) :=
disjoint.mono_right (bsupr_mono $ λ i hi, (ne_of_mem_of_not_mem hi hx : _)) (ht x)
end complete_lattice
lemma complete_lattice.independent_iff_sup_indep [complete_lattice α] {s : finset ι} {f : ι → α} :
complete_lattice.independent (f ∘ (coe : s → ι)) ↔ s.sup_indep f :=
begin
classical,
rw finset.sup_indep_iff_disjoint_erase,
refine subtype.forall.trans (forall₂_congr $ λ a b, _),
rw finset.sup_eq_supr,
congr' 2,
refine supr_subtype.trans _,
congr' 1 with x,
simp [supr_and, @supr_comm _ (x ∈ s)],
end
alias complete_lattice.independent_iff_sup_indep ↔ complete_lattice.independent.sup_indep
finset.sup_indep.independent
/-- A variant of `complete_lattice.independent_iff_sup_indep` for `fintype`s. -/
lemma complete_lattice.independent_iff_sup_indep_univ [complete_lattice α] [fintype ι] {f : ι → α} :
complete_lattice.independent f ↔ finset.univ.sup_indep f :=
begin
classical,
simp [finset.sup_indep_iff_disjoint_erase, complete_lattice.independent, finset.sup_eq_supr],
end
alias complete_lattice.independent_iff_sup_indep_univ ↔ complete_lattice.independent.sup_indep_univ
finset.sup_indep.independent_of_univ
section frame
namespace complete_lattice
variables [order.frame α]
lemma set_independent_iff_pairwise_disjoint {s : set α} :
set_independent s ↔ s.pairwise_disjoint id :=
⟨set_independent.pairwise_disjoint, λ hs i hi, disjoint_Sup_iff.2 $ λ j hj,
hs hi hj.1 $ ne.symm hj.2⟩
alias set_independent_iff_pairwise_disjoint ↔ _ _root_.set.pairwise_disjoint.set_independent
lemma independent_iff_pairwise_disjoint {f : ι → α} : independent f ↔ pairwise (disjoint on f) :=
⟨independent.pairwise_disjoint, λ hs i, disjoint_supr_iff.2 $ λ j, disjoint_supr_iff.2 $ λ hij,
hs hij.symm⟩
end complete_lattice
end frame
|
6a6f783bc7397738c264bba74587ed39d1b40444 | 9dc8cecdf3c4634764a18254e94d43da07142918 | /src/data/multiset/powerset.lean | 675cee9ba82be9a44387ece1ff08095bb93efeff | [
"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 | 10,631 | lean | /-
Copyright (c) 2018 Mario Carneiro. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mario Carneiro
-/
import data.multiset.basic
import data.multiset.range
import data.multiset.bind
/-!
# The powerset of a multiset
-/
namespace multiset
open list
variables {α : Type*}
/-! ### powerset -/
/-- A helper function for the powerset of a multiset. Given a list `l`, returns a list
of sublists of `l` (using `sublists_aux`), as multisets. -/
def powerset_aux (l : list α) : list (multiset α) :=
0 :: sublists_aux l (λ x y, x :: y)
theorem powerset_aux_eq_map_coe {l : list α} :
powerset_aux l = (sublists l).map coe :=
by simp [powerset_aux, sublists];
rw [← show @sublists_aux₁ α (multiset α) l (λ x, [↑x]) =
sublists_aux l (λ x, list.cons ↑x),
from sublists_aux₁_eq_sublists_aux _ _,
sublists_aux_cons_eq_sublists_aux₁,
← bind_ret_eq_map, sublists_aux₁_bind]; refl
@[simp] theorem mem_powerset_aux {l : list α} {s} :
s ∈ powerset_aux l ↔ s ≤ ↑l :=
quotient.induction_on s $
by simp [powerset_aux_eq_map_coe, subperm, and.comm]
/-- Helper function for the powerset of a multiset. Given a list `l`, returns a list
of sublists of `l` (using `sublists'`), as multisets. -/
def powerset_aux' (l : list α) : list (multiset α) := (sublists' l).map coe
theorem powerset_aux_perm_powerset_aux' {l : list α} :
powerset_aux l ~ powerset_aux' l :=
by rw powerset_aux_eq_map_coe; exact (sublists_perm_sublists' _).map _
@[simp] theorem powerset_aux'_nil : powerset_aux' (@nil α) = [0] := rfl
@[simp] theorem powerset_aux'_cons (a : α) (l : list α) :
powerset_aux' (a::l) = powerset_aux' l ++ list.map (cons a) (powerset_aux' l) :=
by simp [powerset_aux']; refl
theorem powerset_aux'_perm {l₁ l₂ : list α} (p : l₁ ~ l₂) :
powerset_aux' l₁ ~ powerset_aux' l₂ :=
begin
induction p with a l₁ l₂ p IH a b l l₁ l₂ l₃ p₁ p₂ IH₁ IH₂, {simp},
{ simp, exact IH.append (IH.map _) },
{ simp, apply perm.append_left,
rw [← append_assoc, ← append_assoc,
(by funext s; simp [cons_swap] : cons b ∘ cons a = cons a ∘ cons b)],
exact perm_append_comm.append_right _ },
{ exact IH₁.trans IH₂ }
end
theorem powerset_aux_perm {l₁ l₂ : list α} (p : l₁ ~ l₂) :
powerset_aux l₁ ~ powerset_aux l₂ :=
powerset_aux_perm_powerset_aux'.trans $
(powerset_aux'_perm p).trans powerset_aux_perm_powerset_aux'.symm
/-- The power set of a multiset. -/
def powerset (s : multiset α) : multiset (multiset α) :=
quot.lift_on s
(λ l, (powerset_aux l : multiset (multiset α)))
(λ l₁ l₂ h, quot.sound (powerset_aux_perm h))
theorem powerset_coe (l : list α) :
@powerset α l = ((sublists l).map coe : list (multiset α)) :=
congr_arg coe powerset_aux_eq_map_coe
@[simp] theorem powerset_coe' (l : list α) :
@powerset α l = ((sublists' l).map coe : list (multiset α)) :=
quot.sound powerset_aux_perm_powerset_aux'
@[simp] theorem powerset_zero : @powerset α 0 = {0} := rfl
@[simp] theorem powerset_cons (a : α) (s) :
powerset (a ::ₘ s) = powerset s + map (cons a) (powerset s) :=
quotient.induction_on s $ λ l, by simp; refl
@[simp] theorem mem_powerset {s t : multiset α} :
s ∈ powerset t ↔ s ≤ t :=
quotient.induction_on₂ s t $ by simp [subperm, and.comm]
theorem map_single_le_powerset (s : multiset α) :
s.map singleton ≤ powerset s :=
quotient.induction_on s $ λ l, begin
simp only [powerset_coe, quot_mk_to_coe, coe_le, coe_map],
show l.map (coe ∘ list.ret) <+~ (sublists l).map coe,
rw ← list.map_map,
exact ((map_ret_sublist_sublists _).map _).subperm
end
@[simp] theorem card_powerset (s : multiset α) :
card (powerset s) = 2 ^ card s :=
quotient.induction_on s $ by simp
theorem revzip_powerset_aux {l : list α} ⦃x⦄
(h : x ∈ revzip (powerset_aux l)) : x.1 + x.2 = ↑l :=
begin
rw [revzip, powerset_aux_eq_map_coe, ← map_reverse, zip_map, ← revzip] at h,
simp at h, rcases h with ⟨l₁, l₂, h, rfl, rfl⟩,
exact quot.sound (revzip_sublists _ _ _ h)
end
theorem revzip_powerset_aux' {l : list α} ⦃x⦄
(h : x ∈ revzip (powerset_aux' l)) : x.1 + x.2 = ↑l :=
begin
rw [revzip, powerset_aux', ← map_reverse, zip_map, ← revzip] at h,
simp at h, rcases h with ⟨l₁, l₂, h, rfl, rfl⟩,
exact quot.sound (revzip_sublists' _ _ _ h)
end
theorem revzip_powerset_aux_lemma [decidable_eq α] (l : list α)
{l' : list (multiset α)} (H : ∀ ⦃x : _ × _⦄, x ∈ revzip l' → x.1 + x.2 = ↑l) :
revzip l' = l'.map (λ x, (x, ↑l - x)) :=
begin
have : forall₂ (λ (p : multiset α × multiset α) (s : multiset α), p = (s, ↑l - s))
(revzip l') ((revzip l').map prod.fst),
{ rw [forall₂_map_right_iff, forall₂_same],
rintro ⟨s, t⟩ h,
dsimp, rw [← H h, add_tsub_cancel_left] },
rw [← forall₂_eq_eq_eq, forall₂_map_right_iff], simpa
end
theorem revzip_powerset_aux_perm_aux' {l : list α} :
revzip (powerset_aux l) ~ revzip (powerset_aux' l) :=
begin
haveI := classical.dec_eq α,
rw [revzip_powerset_aux_lemma l revzip_powerset_aux,
revzip_powerset_aux_lemma l revzip_powerset_aux'],
exact powerset_aux_perm_powerset_aux'.map _
end
theorem revzip_powerset_aux_perm {l₁ l₂ : list α} (p : l₁ ~ l₂) :
revzip (powerset_aux l₁) ~ revzip (powerset_aux l₂) :=
begin
haveI := classical.dec_eq α,
simp [λ l:list α, revzip_powerset_aux_lemma l revzip_powerset_aux, coe_eq_coe.2 p],
exact (powerset_aux_perm p).map _
end
/-! ### powerset_len -/
/-- Helper function for `powerset_len`. Given a list `l`, `powerset_len_aux n l` is the list
of sublists of length `n`, as multisets. -/
def powerset_len_aux (n : ℕ) (l : list α) : list (multiset α) :=
sublists_len_aux n l coe []
theorem powerset_len_aux_eq_map_coe {n} {l : list α} :
powerset_len_aux n l = (sublists_len n l).map coe :=
by rw [powerset_len_aux, sublists_len_aux_eq, append_nil]
@[simp] theorem mem_powerset_len_aux {n} {l : list α} {s} :
s ∈ powerset_len_aux n l ↔ s ≤ ↑l ∧ card s = n :=
quotient.induction_on s $
by simp [powerset_len_aux_eq_map_coe, subperm]; exact
λ l₁, ⟨λ ⟨l₂, ⟨s, e⟩, p⟩, ⟨⟨_, p, s⟩, p.symm.length_eq.trans e⟩,
λ ⟨⟨l₂, p, s⟩, e⟩, ⟨_, ⟨s, p.length_eq.trans e⟩, p⟩⟩
@[simp] theorem powerset_len_aux_zero (l : list α) :
powerset_len_aux 0 l = [0] :=
by simp [powerset_len_aux_eq_map_coe]
@[simp] theorem powerset_len_aux_nil (n : ℕ) :
powerset_len_aux (n+1) (@nil α) = [] := rfl
@[simp] theorem powerset_len_aux_cons (n : ℕ) (a : α) (l : list α) :
powerset_len_aux (n+1) (a::l) =
powerset_len_aux (n+1) l ++ list.map (cons a) (powerset_len_aux n l) :=
by simp [powerset_len_aux_eq_map_coe]; refl
theorem powerset_len_aux_perm {n} {l₁ l₂ : list α} (p : l₁ ~ l₂) :
powerset_len_aux n l₁ ~ powerset_len_aux n l₂ :=
begin
induction n with n IHn generalizing l₁ l₂, {simp},
induction p with a l₁ l₂ p IH a b l l₁ l₂ l₃ p₁ p₂ IH₁ IH₂, {refl},
{ simp, exact IH.append ((IHn p).map _) },
{ simp, apply perm.append_left,
cases n, {simp, apply perm.swap},
simp,
rw [← append_assoc, ← append_assoc,
(by funext s; simp [cons_swap] : cons b ∘ cons a = cons a ∘ cons b)],
exact perm_append_comm.append_right _ },
{ exact IH₁.trans IH₂ }
end
/-- `powerset_len n s` is the multiset of all submultisets of `s` of length `n`. -/
def powerset_len (n : ℕ) (s : multiset α) : multiset (multiset α) :=
quot.lift_on s
(λ l, (powerset_len_aux n l : multiset (multiset α)))
(λ l₁ l₂ h, quot.sound (powerset_len_aux_perm h))
theorem powerset_len_coe' (n) (l : list α) :
@powerset_len α n l = powerset_len_aux n l := rfl
theorem powerset_len_coe (n) (l : list α) :
@powerset_len α n l = ((sublists_len n l).map coe : list (multiset α)) :=
congr_arg coe powerset_len_aux_eq_map_coe
@[simp] theorem powerset_len_zero_left (s : multiset α) :
powerset_len 0 s = {0} :=
quotient.induction_on s $ λ l, by simp [powerset_len_coe']; refl
theorem powerset_len_zero_right (n : ℕ) :
@powerset_len α (n + 1) 0 = 0 := rfl
@[simp] theorem powerset_len_cons (n : ℕ) (a : α) (s) :
powerset_len (n + 1) (a ::ₘ s) =
powerset_len (n + 1) s + map (cons a) (powerset_len n s) :=
quotient.induction_on s $ λ l, by simp [powerset_len_coe']; refl
@[simp] theorem mem_powerset_len {n : ℕ} {s t : multiset α} :
s ∈ powerset_len n t ↔ s ≤ t ∧ card s = n :=
quotient.induction_on t $ λ l, by simp [powerset_len_coe']
@[simp] theorem card_powerset_len (n : ℕ) (s : multiset α) :
card (powerset_len n s) = nat.choose (card s) n :=
quotient.induction_on s $ by simp [powerset_len_coe]
theorem powerset_len_le_powerset (n : ℕ) (s : multiset α) :
powerset_len n s ≤ powerset s :=
quotient.induction_on s $ λ l, by simp [powerset_len_coe]; exact
((sublists_len_sublist_sublists' _ _).map _).subperm
theorem powerset_len_mono (n : ℕ) {s t : multiset α} (h : s ≤ t) :
powerset_len n s ≤ powerset_len n t :=
le_induction_on h $ λ l₁ l₂ h, by simp [powerset_len_coe]; exact
((sublists_len_sublist_of_sublist _ h).map _).subperm
@[simp] theorem powerset_len_empty {α : Type*} (n : ℕ) {s : multiset α} (h : s.card < n) :
powerset_len n s = 0 :=
card_eq_zero.mp (nat.choose_eq_zero_of_lt h ▸ card_powerset_len _ _)
@[simp]
lemma powerset_len_card_add (s : multiset α) {i : ℕ} (hi : 0 < i) :
s.powerset_len (s.card + i) = 0 :=
powerset_len_empty _ (lt_add_of_pos_right (card s) hi)
theorem powerset_len_map {β : Type*} (f : α → β) (n : ℕ) (s : multiset α) :
powerset_len n (s.map f) = (powerset_len n s).map (map f) :=
begin
induction s using multiset.induction with t s ih generalizing n,
{ cases n; simp [powerset_len_zero_left, powerset_len_zero_right], },
{ cases n; simp [ih, map_comp_cons], },
end
lemma disjoint_powerset_len (s : multiset α) {i j : ℕ} (h : i ≠ j) :
multiset.disjoint (s.powerset_len i) (s.powerset_len j) :=
λ x hi hj, h (eq.trans (multiset.mem_powerset_len.mp hi).right.symm
(multiset.mem_powerset_len.mp hj).right)
lemma bind_powerset_len {α : Type*} (S : multiset α) :
bind (multiset.range (S.card + 1)) (λ k, S.powerset_len k) = S.powerset :=
begin
induction S using quotient.induction_on,
simp_rw [quot_mk_to_coe, powerset_coe', powerset_len_coe, ←coe_range, coe_bind, ←list.bind_map,
coe_card],
exact coe_eq_coe.mpr ((list.range_bind_sublists_len_perm S).map _),
end
end multiset
|
e0954cf5d6f26c144279d495ea197056d0d02950 | c777c32c8e484e195053731103c5e52af26a25d1 | /src/probability/kernel/invariance.lean | 75ccfd8c63442e949bf628b55f9afde17842ff2d | [
"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 | 5,311 | lean | /-
Copyright (c) 2023 Kexing Ying. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Kexing Ying
-/
import probability.kernel.composition
/-!
# Invariance of measures along a kernel
We define the push-forward of a measure along a kernel which results in another measure. In the
case that the push-forward measure is the same as the original measure, we say that the measure is
invariant with respect to the kernel.
## Main definitions
* `probability_theory.kernel.map_measure`: the push-forward of a measure along a kernel.
* `probability_theory.kernel.invariant`: invariance of a given measure with respect to a kernel.
## Useful lemmas
* `probability_theory.kernel.comp_apply_eq_map_measure`,
`probability_theory.kernel.const_map_measure_eq_comp_const`, and
`probability_theory.kernel.comp_const_apply_eq_map_measure` established the relationship between
the push-forward measure and the composition of kernels.
-/
open measure_theory
open_locale measure_theory ennreal probability_theory
namespace probability_theory
variables {α β γ : Type*} {mα : measurable_space α} {mβ : measurable_space β}
{mγ : measurable_space γ}
include mα mβ
namespace kernel
/-! ### Push-forward of measures along a kernel -/
/-- The push-forward of a measure along a kernel. -/
noncomputable
def map_measure (κ : kernel α β) (μ : measure α) :
measure β :=
measure.of_measurable (λ s hs, ∫⁻ x, κ x s ∂μ)
(by simp only [measure_empty, measure_theory.lintegral_const, zero_mul])
begin
intros f hf₁ hf₂,
simp_rw [measure_Union hf₂ hf₁,
lintegral_tsum (λ i, (kernel.measurable_coe κ (hf₁ i)).ae_measurable)],
end
@[simp]
lemma map_measure_apply (κ : kernel α β) (μ : measure α) {s : set β} (hs : measurable_set s) :
map_measure κ μ s = ∫⁻ x, κ x s ∂μ :=
by rw [map_measure, measure.of_measurable_apply s hs]
@[simp]
lemma map_measure_zero (κ : kernel α β) : map_measure κ 0 = 0 :=
begin
ext1 s hs,
rw [map_measure_apply κ 0 hs, lintegral_zero_measure, measure.coe_zero, pi.zero_apply],
end
@[simp]
lemma map_measure_add (κ : kernel α β) (μ ν : measure α) :
map_measure κ (μ + ν) = map_measure κ μ + map_measure κ ν :=
begin
ext1 s hs,
rw [map_measure_apply κ (μ + ν) hs, lintegral_add_measure, measure.coe_add, pi.add_apply,
map_measure_apply κ μ hs, map_measure_apply κ ν hs],
end
@[simp]
lemma map_measure_smul (κ : kernel α β) (μ : measure α) (r : ℝ≥0∞) :
map_measure κ (r • μ) = r • map_measure κ μ :=
begin
ext1 s hs,
rw [map_measure_apply κ (r • μ) hs, lintegral_smul_measure, measure.coe_smul, pi.smul_apply,
map_measure_apply κ μ hs, smul_eq_mul],
end
include mγ
lemma comp_apply_eq_map_measure
(η : kernel β γ) [is_s_finite_kernel η] (κ : kernel α β) [is_s_finite_kernel κ] (a : α) :
(η ∘ₖ κ) a = map_measure η (κ a) :=
begin
ext1 s hs,
rw [comp_apply η κ a hs, map_measure_apply η _ hs],
end
omit mγ
lemma const_map_measure_eq_comp_const (κ : kernel α β) [is_s_finite_kernel κ]
(μ : measure α) [is_finite_measure μ] :
const α (map_measure κ μ) = κ ∘ₖ const α μ :=
begin
ext1 a, ext1 s hs,
rw [const_apply, map_measure_apply _ _ hs, comp_apply _ _ _ hs, const_apply],
end
lemma comp_const_apply_eq_map_measure (κ : kernel α β) [is_s_finite_kernel κ]
(μ : measure α) [is_finite_measure μ] (a : α) :
(κ ∘ₖ const α μ) a = map_measure κ μ :=
by rw [← const_apply (map_measure κ μ) a, const_map_measure_eq_comp_const κ μ]
lemma lintegral_map_measure
(κ : kernel α β) [is_s_finite_kernel κ] (μ : measure α) [is_finite_measure μ]
{f : β → ℝ≥0∞} (hf : measurable f) :
∫⁻ b, f b ∂(map_measure κ μ) = ∫⁻ a, ∫⁻ b, f b ∂(κ a) ∂μ :=
begin
by_cases hα : nonempty α,
{ have := const_apply μ hα.some,
swap, apply_instance,
conv_rhs { rw [← this] },
rw [← lintegral_comp _ _ _ hf, ← comp_const_apply_eq_map_measure κ μ hα.some] },
{ haveI := not_nonempty_iff.1 hα,
rw [μ.eq_zero_of_is_empty, map_measure_zero, lintegral_zero_measure,
lintegral_zero_measure] }
end
omit mβ
/-! ### Invariant measures of kernels -/
/-- A measure `μ` is invariant with respect to the kernel `κ` if the push-forward measure of `μ`
along `κ` equals `μ`. -/
def invariant (κ : kernel α α) (μ : measure α) : Prop :=
map_measure κ μ = μ
variables {κ η : kernel α α} {μ : measure α}
lemma invariant.def (hκ : invariant κ μ) : map_measure κ μ = μ := hκ
lemma invariant.comp_const [is_s_finite_kernel κ] [is_finite_measure μ]
(hκ : invariant κ μ) : (κ ∘ₖ const α μ) = const α μ :=
by rw [← const_map_measure_eq_comp_const κ μ, hκ.def]
lemma invariant.comp [is_s_finite_kernel κ] [is_s_finite_kernel η] [is_finite_measure μ]
(hκ : invariant κ μ) (hη : invariant η μ) : invariant (κ ∘ₖ η) μ :=
begin
by_cases hα : nonempty α,
{ simp_rw [invariant, ← comp_const_apply_eq_map_measure (κ ∘ₖ η) μ hα.some, comp_assoc,
hη.comp_const, hκ.comp_const, const_apply] },
{ haveI := not_nonempty_iff.1 hα,
exact subsingleton.elim _ _ },
end
end kernel
end probability_theory
|
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