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@[simps] equivalenceLeftToRight (F : Arrow C) (X : CosimplicialObject.Augmented C) (G : F.augmentedCechConerve ⟶ X) : F ⟶ Augmented.toArrow.obj X where left := G.left right := (WidePushout.ι _ 0 ≫ G.right.app ⦋0⦌ :) w := by dsimp rw [@WidePushout.arrow_ι_assoc _ _ _ _ _ (fun (_ : Fin 1) => F.hom) (by dsimp; infer_instance)] exact congr_app G.w ⦋0⦌
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
equivalenceLeftToRight
A helper function used in defining the Čech conerve adjunction.
@[simps!] equivalenceRightToLeft (F : Arrow C) (X : CosimplicialObject.Augmented C) (G : F ⟶ Augmented.toArrow.obj X) : F.augmentedCechConerve ⟶ X where left := G.left right := { app := fun x => Limits.WidePushout.desc (G.left ≫ X.hom.app _) (fun i => G.right ≫ X.right.map (SimplexCategory.const _ x i)) (by rintro j rw [← Arrow.w_assoc G] have t := X.hom.naturality (SimplexCategory.const ⦋0⦌ x j) dsimp at t ⊢ simp only [Category.id_comp] at t rw [← t]) naturality := by intro x y f dsimp ext · dsimp simp only [WidePushout.ι_desc_assoc, WidePushout.ι_desc] rw [Category.assoc, ← X.right.map_comp] rfl · simp [← NatTrans.naturality] }
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
equivalenceRightToLeft
A helper function used in defining the Čech conerve adjunction.
@[simps] cechConerveEquiv (F : Arrow C) (X : CosimplicialObject.Augmented C) : (F.augmentedCechConerve ⟶ X) ≃ (F ⟶ Augmented.toArrow.obj X) where toFun := equivalenceLeftToRight _ _ invFun := equivalenceRightToLeft _ _ left_inv := by intro A ext x : 2 · rfl · refine WidePushout.hom_ext _ _ _ (fun j => ?_) ?_ · dsimp simp only [Category.assoc, ← NatTrans.naturality A.right, Arrow.augmentedCechConerve_right, SimplexCategory.len_mk, Arrow.cechConerve_map, colimit.ι_desc, WidePushoutShape.mkCocone_ι_app, colimit.ι_desc_assoc] rfl · dsimp rw [colimit.ι_desc] exact congr_app A.w x right_inv := by intro A ext · rfl · dsimp rw [WidePushout.ι_desc] nth_rw 2 [← Category.comp_id A.right] congr 1 convert X.right.map_id _ ext ⟨a, ha⟩ simp
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
cechConerveEquiv
A helper function used in defining the Čech conerve adjunction.
cechConerveAdjunction : augmentedCechConerve ⊣ (Augmented.toArrow : _ ⥤ Arrow C) := Adjunction.mkOfHomEquiv { homEquiv := cechConerveEquiv }
abbrev
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
cechConerveAdjunction
The augmented Čech conerve construction is left adjoint to the `toArrow` functor.
cechNerveTerminalFrom {C : Type u} [Category.{v} C] [HasFiniteProducts C] (X : C) : SimplicialObject C where obj n := ∏ᶜ fun _ : Fin (n.unop.len + 1) => X map f := Limits.Pi.lift fun i => Limits.Pi.π _ (f.unop.toOrderHom i)
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
cechNerveTerminalFrom
Given an object `X : C`, the natural simplicial object sending `⦋n⦌` to `Xⁿ⁺¹`.
wideCospan (X : C) : WidePullbackShape ι ⥤ C := WidePullbackShape.wideCospan (terminal C) (fun _ : ι => X) fun _ => terminal.from X
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
wideCospan
The diagram `Option ι ⥤ C` sending `none` to the terminal object and `some j` to `X`.
uniqueToWideCospanNone (X Y : C) : Unique (Y ⟶ (wideCospan ι X).obj none) := by dsimp [wideCospan] infer_instance variable [HasFiniteProducts C]
instance
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
uniqueToWideCospanNone
null
wideCospan.limitCone [Finite ι] (X : C) : LimitCone (wideCospan ι X) where cone := { pt := ∏ᶜ fun _ : ι => X π := { app := fun X => Option.casesOn X (terminal.from _) fun i => limit.π _ ⟨i⟩ naturality := fun i j f => by cases f · cases i all_goals simp · simp only [Functor.const_obj_obj, Functor.const_obj_map, terminal.comp_from] subsingleton } } isLimit := { lift := fun s => Limits.Pi.lift fun j => s.π.app (some j) fac := fun s j => Option.casesOn j (by subsingleton) fun _ => limit.lift_π _ _ uniq := fun s f h => by dsimp ext j dsimp only [Limits.Pi.lift] rw [limit.lift_π] dsimp rw [← h (some j)] }
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
wideCospan.limitCone
The product `Xᶥ` is the vertex of a limit cone on `wideCospan ι X`.
hasWidePullback [Finite ι] (X : C) : HasWidePullback (Arrow.mk (terminal.from X)).right (fun _ : ι => (Arrow.mk (terminal.from X)).left) (fun _ => (Arrow.mk (terminal.from X)).hom) := by cases nonempty_fintype ι exact ⟨⟨wideCospan.limitCone ι X⟩⟩
instance
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
hasWidePullback
null
hasWidePullback' [Finite ι] (X : C) : HasWidePullback (⊤_ C) (fun _ : ι => X) (fun _ => terminal.from X) := hasWidePullback _ _
instance
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
hasWidePullback'
null
hasLimit_wideCospan [Finite ι] (X : C) : HasLimit (wideCospan ι X) := hasWidePullback _ _
instance
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
hasLimit_wideCospan
null
wideCospan.limitIsoPi [Finite ι] (X : C) : limit (wideCospan ι X) ≅ ∏ᶜ fun _ : ι => X := (IsLimit.conePointUniqueUpToIso (limit.isLimit _) (wideCospan.limitCone ι X).2) @[reassoc (attr := simp)]
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
wideCospan.limitIsoPi
the isomorphism to the product induced by the limit cone `wideCospan ι X`
wideCospan.limitIsoPi_inv_comp_pi [Finite ι] (X : C) (j : ι) : (wideCospan.limitIsoPi ι X).inv ≫ WidePullback.π _ j = Pi.π _ j := IsLimit.conePointUniqueUpToIso_inv_comp _ _ _ @[reassoc (attr := simp)]
lemma
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
wideCospan.limitIsoPi_inv_comp_pi
null
wideCospan.limitIsoPi_hom_comp_pi [Finite ι] (X : C) (j : ι) : (wideCospan.limitIsoPi ι X).hom ≫ Pi.π _ j = WidePullback.π _ j := by rw [← wideCospan.limitIsoPi_inv_comp_pi, Iso.hom_inv_id_assoc]
lemma
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
wideCospan.limitIsoPi_hom_comp_pi
null
iso (X : C) : (Arrow.mk (terminal.from X)).cechNerve ≅ cechNerveTerminalFrom X := NatIso.ofComponents (fun _ => wideCospan.limitIsoPi _ _) (fun {m n} f => by dsimp only [cechNerveTerminalFrom, Arrow.cechNerve] ext ⟨j⟩ simp)
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Comma.Arrow", "Mathlib.CategoryTheory.Limits.Shapes.WidePullbacks", "Mathlib.CategoryTheory.Limits.Shapes.FiniteProducts" ]
Mathlib/AlgebraicTopology/CechNerve.lean
iso
Given an object `X : C`, the Čech nerve of the hom to the terminal object `X ⟶ ⊤_ C` is naturally isomorphic to a simplicial object sending `⦋n⦌` to `Xⁿ⁺¹` (when `C` is `G-Set`, this is `EG`, the universal cover of the classifying space of `G`.
@[ext] ExtraDegeneracy (X : SimplicialObject.Augmented C) where /-- a section of the augmentation in dimension `0` -/ s' : point.obj X ⟶ drop.obj X _⦋0⦌ /-- the extra degeneracy -/ s : ∀ n : ℕ, drop.obj X _⦋n⦌ ⟶ drop.obj X _⦋n + 1⦌ s'_comp_ε : s' ≫ X.hom.app (op ⦋0⦌) = 𝟙 _ := by cat_disch s₀_comp_δ₁ : s 0 ≫ X.left.δ 1 = X.hom.app (op ⦋0⦌) ≫ s' := by cat_disch s_comp_δ₀ : ∀ n : ℕ, s n ≫ X.left.δ 0 = 𝟙 _ := by cat_disch s_comp_δ : ∀ (n : ℕ) (i : Fin (n + 2)), s (n + 1) ≫ X.left.δ i.succ = X.left.δ i ≫ s n := by cat_disch s_comp_σ : ∀ (n : ℕ) (i : Fin (n + 1)), s n ≫ X.left.σ i.succ = X.left.σ i ≫ s (n + 1) := by cat_disch
structure
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
ExtraDegeneracy
The datum of an extra degeneracy is a technical condition on augmented simplicial objects. The morphisms `s'` and `s n` of the structure formally behave like extra degeneracies `σ (-1)`.
map {D : Type*} [Category D] {X : SimplicialObject.Augmented C} (ed : ExtraDegeneracy X) (F : C ⥤ D) : ExtraDegeneracy (((whiskering _ _).obj F).obj X) where s' := F.map ed.s' s n := F.map (ed.s n) s'_comp_ε := by dsimp rw [comp_id, ← F.map_comp, ed.s'_comp_ε] dsimp only [point_obj] rw [F.map_id] s₀_comp_δ₁ := by dsimp rw [comp_id, ← F.map_comp] dsimp [SimplicialObject.whiskering, SimplicialObject.δ] rw [← F.map_comp] erw [ed.s₀_comp_δ₁] s_comp_δ₀ n := by dsimp [SimplicialObject.δ] rw [← F.map_comp] erw [ed.s_comp_δ₀] dsimp rw [F.map_id] s_comp_δ n i := by dsimp [SimplicialObject.δ] rw [← F.map_comp, ← F.map_comp] erw [ed.s_comp_δ] rfl s_comp_σ n i := by dsimp [SimplicialObject.whiskering, SimplicialObject.σ] rw [← F.map_comp, ← F.map_comp] erw [ed.s_comp_σ] rfl
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
map
If `ed` is an extra degeneracy for `X : SimplicialObject.Augmented C` and `F : C ⥤ D` is a functor, then `ed.map F` is an extra degeneracy for the augmented simplicial object in `D` obtained by applying `F` to `X`.
ofIso {X Y : SimplicialObject.Augmented C} (e : X ≅ Y) (ed : ExtraDegeneracy X) : ExtraDegeneracy Y where s' := (point.mapIso e).inv ≫ ed.s' ≫ (drop.mapIso e).hom.app (op ⦋0⦌) s n := (drop.mapIso e).inv.app (op ⦋n⦌) ≫ ed.s n ≫ (drop.mapIso e).hom.app (op ⦋n + 1⦌) s'_comp_ε := by simpa only [Functor.mapIso, assoc, w₀, ed.s'_comp_ε_assoc] using (point.mapIso e).inv_hom_id s₀_comp_δ₁ := by have h := w₀ e.inv dsimp at h ⊢ simp only [assoc, ← SimplicialObject.δ_naturality, ed.s₀_comp_δ₁_assoc, reassoc_of% h] s_comp_δ₀ n := by have h := ed.s_comp_δ₀ dsimp at h ⊢ simpa only [assoc, ← SimplicialObject.δ_naturality, reassoc_of% h] using congr_app (drop.mapIso e).inv_hom_id (op ⦋n⦌) s_comp_δ n i := by have h := ed.s_comp_δ n i dsimp at h ⊢ simp only [assoc, ← SimplicialObject.δ_naturality, reassoc_of% h, ← SimplicialObject.δ_naturality_assoc] s_comp_σ n i := by have h := ed.s_comp_σ n i dsimp at h ⊢ simp only [assoc, ← SimplicialObject.σ_naturality, reassoc_of% h, ← SimplicialObject.σ_naturality_assoc]
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
ofIso
If `X` and `Y` are isomorphic augmented simplicial objects, then an extra degeneracy for `X` gives also an extra degeneracy for `Y`
shiftFun {n : ℕ} {X : Type*} [Zero X] (f : Fin n → X) (i : Fin (n + 1)) : X := Matrix.vecCons 0 f i @[simp]
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
shiftFun
When `[Zero X]`, the shift of a map `f : Fin n → X` is a map `Fin (n + 1) → X` which sends `0` to `0` and `i.succ` to `f i`.
shiftFun_zero {n : ℕ} {X : Type*} [Zero X] (f : Fin n → X) : shiftFun f 0 = 0 := rfl @[deprecated (since := "2025-04-19")] alias shiftFun_0 := shiftFun_zero @[simp]
theorem
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
shiftFun_zero
null
shiftFun_succ {n : ℕ} {X : Type*} [Zero X] (f : Fin n → X) (i : Fin n) : shiftFun f i.succ = f i := rfl
theorem
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
shiftFun_succ
null
@[simp] shift {n : ℕ} {Δ : SimplexCategory} (f : ⦋n⦌ ⟶ Δ) : ⦋n + 1⦌ ⟶ Δ := SimplexCategory.Hom.mk { toFun := shiftFun f.toOrderHom monotone' := fun i₁ i₂ hi => by by_cases h₁ : i₁ = 0 · subst h₁ simp only [shiftFun_zero, Fin.zero_le] · have h₂ : i₂ ≠ 0 := by intro h₂ subst h₂ exact h₁ (le_antisymm hi (Fin.zero_le _)) obtain ⟨j₁, hj₁⟩ := Fin.eq_succ_of_ne_zero h₁ obtain ⟨j₂, hj₂⟩ := Fin.eq_succ_of_ne_zero h₂ substs hj₁ hj₂ simpa only [shiftFun_succ] using f.toOrderHom.monotone (Fin.succ_le_succ_iff.mp hi) } open SSet.stdSimplex in
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
shift
The shift of a morphism `f : ⦋n⦌ → Δ` in `SimplexCategory` corresponds to the monotone map which sends `0` to `0` and `i.succ` to `f.toOrderHom i`.
protected noncomputable extraDegeneracy (Δ : SimplexCategory) : SimplicialObject.Augmented.ExtraDegeneracy (stdSimplex.obj Δ) where s' _ := objMk (OrderHom.const _ 0) s _ f := objEquiv.symm (shift (objEquiv f)) s'_comp_ε := by dsimp subsingleton s₀_comp_δ₁ := by dsimp ext1 x apply objEquiv.injective ext j fin_cases j rfl s_comp_δ₀ n := by ext1 φ apply objEquiv.injective apply SimplexCategory.Hom.ext ext i : 2 dsimp [SimplicialObject.δ, SimplexCategory.δ, SSet.stdSimplex, objEquiv, Equiv.ulift, uliftFunctor] s_comp_δ n i := by ext1 φ apply objEquiv.injective apply SimplexCategory.Hom.ext ext j : 2 dsimp [SimplicialObject.δ, SimplexCategory.δ, SSet.stdSimplex, objEquiv, Equiv.ulift, uliftFunctor] cases j using Fin.cases <;> simp s_comp_σ n i := by ext1 φ apply objEquiv.injective apply SimplexCategory.Hom.ext ext j : 2 dsimp [SimplicialObject.σ, SimplexCategory.σ, SSet.stdSimplex, objEquiv, Equiv.ulift, uliftFunctor, Function.comp_def] cases j using Fin.cases <;> simp
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
extraDegeneracy
The obvious extra degeneracy on the standard simplex.
nonempty_extraDegeneracy_stdSimplex (Δ : SimplexCategory) : Nonempty (SimplicialObject.Augmented.ExtraDegeneracy (stdSimplex.obj Δ)) := ⟨StandardSimplex.extraDegeneracy Δ⟩
instance
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
nonempty_extraDegeneracy_stdSimplex
null
noncomputable ExtraDegeneracy.s (n : ℕ) : f.cechNerve.obj (op ⦋n⦌) ⟶ f.cechNerve.obj (op ⦋n + 1⦌) := WidePullback.lift (WidePullback.base _) (Fin.cases (WidePullback.base _ ≫ S.section_) (WidePullback.π _)) fun i => by cases i using Fin.cases <;> simp
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
ExtraDegeneracy.s
The extra degeneracy map on the Čech nerve of a split epi. It is given on the `0`-projection by the given section of the split epi, and by shifting the indices on the other projections.
ExtraDegeneracy.s_comp_π_0 (n : ℕ) : ExtraDegeneracy.s f S n ≫ WidePullback.π _ 0 = @WidePullback.base _ _ _ f.right (fun _ : Fin (n + 1) => f.left) (fun _ => f.hom) _ ≫ S.section_ := by dsimp [ExtraDegeneracy.s] simp
theorem
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
ExtraDegeneracy.s_comp_π_0
null
ExtraDegeneracy.s_comp_π_succ (n : ℕ) (i : Fin (n + 1)) : ExtraDegeneracy.s f S n ≫ WidePullback.π _ i.succ = @WidePullback.π _ _ _ f.right (fun _ : Fin (n + 1) => f.left) (fun _ => f.hom) _ i := by simp [ExtraDegeneracy.s]
theorem
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
ExtraDegeneracy.s_comp_π_succ
null
ExtraDegeneracy.s_comp_base (n : ℕ) : ExtraDegeneracy.s f S n ≫ WidePullback.base _ = WidePullback.base _ := by apply WidePullback.lift_base
theorem
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
ExtraDegeneracy.s_comp_base
null
noncomputable extraDegeneracy : SimplicialObject.Augmented.ExtraDegeneracy f.augmentedCechNerve where s' := S.section_ ≫ WidePullback.lift f.hom (fun _ => 𝟙 _) fun i => by rw [id_comp] s n := ExtraDegeneracy.s f S n s'_comp_ε := by dsimp simp only [assoc, WidePullback.lift_base, SplitEpi.id] s₀_comp_δ₁ := by dsimp [cechNerve, SimplicialObject.δ, SimplexCategory.δ] ext j · fin_cases j simpa only [assoc, WidePullback.lift_π, comp_id] using ExtraDegeneracy.s_comp_π_0 f S 0 · simpa only [assoc, WidePullback.lift_base, SplitEpi.id, comp_id] using ExtraDegeneracy.s_comp_base f S 0 s_comp_δ₀ n := by dsimp [cechNerve, SimplicialObject.δ, SimplexCategory.δ] ext j · simpa only [assoc, WidePullback.lift_π, id_comp] using ExtraDegeneracy.s_comp_π_succ f S n j · simpa only [assoc, WidePullback.lift_base, id_comp] using ExtraDegeneracy.s_comp_base f S n s_comp_δ n i := by dsimp [SimplicialObject.δ, SimplexCategory.δ] ext j · simp only [assoc, WidePullback.lift_π] cases j using Fin.cases with | zero => rw [Fin.succ_succAbove_zero] erw [ExtraDegeneracy.s_comp_π_0, ExtraDegeneracy.s_comp_π_0] dsimp simp only [WidePullback.lift_base_assoc] | succ k => erw [Fin.succ_succAbove_succ, ExtraDegeneracy.s_comp_π_succ, ExtraDegeneracy.s_comp_π_succ] simp only [WidePullback.lift_π] · simp only [assoc, WidePullback.lift_base] erw [ExtraDegeneracy.s_comp_base, ExtraDegeneracy.s_comp_base] dsimp simp only [WidePullback.lift_base] s_comp_σ n i := by dsimp [cechNerve, SimplicialObject.σ, SimplexCategory.σ] ext j · simp only [assoc, WidePullback.lift_π] cases j using Fin.cases with | zero => erw [ExtraDegeneracy.s_comp_π_0, ExtraDegeneracy.s_comp_π_0] dsimp simp only [WidePullback.lift_base_assoc] | succ k => erw [Fin.succ_predAbove_succ, ExtraDegeneracy.s_comp_π_succ, ExtraDegeneracy.s_comp_π_succ] simp only [WidePullback.lift_π] · simp only [assoc, WidePullback.lift_base] ...
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
extraDegeneracy
The augmented Čech nerve associated to a split epimorphism has an extra degeneracy.
@[simps] const (X : C) : ExtraDegeneracy (Augmented.const.obj X) where s' := 𝟙 _ s _ := 𝟙 _
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
const
The constant augmented simplicial object has an extra degeneracy.
noncomputable homotopyEquiv [Preadditive C] [HasZeroObject C] {X : SimplicialObject.Augmented C} (ed : ExtraDegeneracy X) : HomotopyEquiv (AlgebraicTopology.AlternatingFaceMapComplex.obj (drop.obj X)) ((ChainComplex.single₀ C).obj (point.obj X)) where hom := AlternatingFaceMapComplex.ε.app X inv := (ChainComplex.fromSingle₀Equiv _ _).symm (by exact ed.s') homotopyInvHomId := Homotopy.ofEq (by ext dsimp erw [AlternatingFaceMapComplex.ε_app_f_zero, ChainComplex.fromSingle₀Equiv_symm_apply_f_zero, s'_comp_ε] rfl) homotopyHomInvId := { hom i := Pi.single (i + 1) (-ed.s i) zero i j hij := Pi.single_eq_of_ne (Ne.symm hij) _ comm i := by cases i with | zero => rw [Homotopy.prevD_chainComplex, Homotopy.dNext_zero_chainComplex, zero_add] dsimp erw [ChainComplex.fromSingle₀Equiv_symm_apply_f_zero] simp only [AlternatingFaceMapComplex.obj_d_eq] rw [Fin.sum_univ_two] simp [s_comp_δ₀, s₀_comp_δ₁] | succ i => rw [Homotopy.prevD_chainComplex, Homotopy.dNext_succ_chainComplex] simp [Fin.sum_univ_succ (n := i + 2), s_comp_δ₀, Preadditive.sum_comp, Preadditive.comp_sum, s_comp_δ, pow_succ] }
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.AlternatingFaceMapComplex", "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.CechNerve", "Mathlib.Algebra.Homology.Homotopy", "Mathlib.Tactic.FinCases" ]
Mathlib/AlgebraicTopology/ExtraDegeneracy.lean
homotopyEquiv
If `C` is a preadditive category and `X` is an augmented simplicial object in `C` that has an extra degeneracy, then the augmentation on the alternating face map complex of `X` is a homotopy equivalence.
objX : ∀ n : ℕ, Subobject (X.obj (op ⦋n⦌)) | 0 => ⊤ | n + 1 => Finset.univ.inf fun k : Fin (n + 1) => kernelSubobject (X.δ k.succ) @[simp] theorem objX_zero : objX X 0 = ⊤ := rfl @[simp] theorem objX_add_one (n) : objX X (n + 1) = Finset.univ.inf fun k : Fin (n + 1) => kernelSubobject (X.δ k.succ) := rfl
def
AlgebraicTopology
[ "Mathlib.Algebra.Homology.HomologicalComplex", "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Abelian.Basic" ]
Mathlib/AlgebraicTopology/MooreComplex.lean
objX
The normalized Moore complex in degree `n`, as a subobject of `X n`.
@[simp] objD : ∀ n : ℕ, (objX X (n + 1) : C) ⟶ (objX X n : C) | 0 => Subobject.arrow _ ≫ X.δ (0 : Fin 2) ≫ inv (⊤ : Subobject _).arrow | n + 1 => by refine factorThru _ (arrow _ ≫ X.δ (0 : Fin (n + 3))) ?_ refine (finset_inf_factors _).mpr fun i _ => ?_ apply kernelSubobject_factors dsimp [objX] rw [Category.assoc, ← Fin.castSucc_zero, ← X.δ_comp_δ (Fin.zero_le i.succ)] rw [← factorThru_arrow _ _ (finset_inf_arrow_factors Finset.univ _ i.succ (by simp)), Category.assoc, kernelSubobject_arrow_comp_assoc, zero_comp, comp_zero]
def
AlgebraicTopology
[ "Mathlib.Algebra.Homology.HomologicalComplex", "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Abelian.Basic" ]
Mathlib/AlgebraicTopology/MooreComplex.lean
objD
The differentials in the normalized Moore complex.
d_squared (n : ℕ) : objD X (n + 1) ≫ objD X n = 0 := by rcases n with _ | n <;> dsimp [objD] · rw [Subobject.factorThru_arrow_assoc, Category.assoc, ← Fin.castSucc_zero, ← X.δ_comp_δ_assoc (Fin.zero_le (0 : Fin 2)), ← factorThru_arrow _ _ (finset_inf_arrow_factors Finset.univ _ (0 : Fin 2) (by simp)), Category.assoc, kernelSubobject_arrow_comp_assoc, zero_comp, comp_zero] · rw [factorThru_right, factorThru_eq_zero, factorThru_arrow_assoc, Category.assoc, ← Fin.castSucc_zero, ← X.δ_comp_δ (Fin.zero_le (0 : Fin (n + 3))), ← factorThru_arrow _ _ (finset_inf_arrow_factors Finset.univ _ (0 : Fin (n + 3)) (by simp)), Category.assoc, kernelSubobject_arrow_comp_assoc, zero_comp, comp_zero]
theorem
AlgebraicTopology
[ "Mathlib.Algebra.Homology.HomologicalComplex", "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Abelian.Basic" ]
Mathlib/AlgebraicTopology/MooreComplex.lean
d_squared
null
@[simps!] obj (X : SimplicialObject C) : ChainComplex C ℕ := ChainComplex.of (fun n => (objX X n : C)) (-- the coercion here picks a representative of the subobject objD X) (d_squared X) variable {X} {Y : SimplicialObject C} (f : X ⟶ Y)
def
AlgebraicTopology
[ "Mathlib.Algebra.Homology.HomologicalComplex", "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Abelian.Basic" ]
Mathlib/AlgebraicTopology/MooreComplex.lean
obj
The normalized Moore complex functor, on objects.
@[simps!] map (f : X ⟶ Y) : obj X ⟶ obj Y := ChainComplex.ofHom _ _ _ _ _ _ (fun n => factorThru _ (arrow _ ≫ f.app (op ⦋n⦌)) (by cases n <;> dsimp · apply top_factors · refine (finset_inf_factors _).mpr fun i _ => kernelSubobject_factors _ _ ?_ rw [Category.assoc, SimplicialObject.δ, ← f.naturality, ← factorThru_arrow _ _ (finset_inf_arrow_factors Finset.univ _ i (by simp)), Category.assoc] erw [kernelSubobject_arrow_comp_assoc] rw [zero_comp, comp_zero])) fun n => by cases n <;> dsimp [objD, objX] <;> cat_disch
def
AlgebraicTopology
[ "Mathlib.Algebra.Homology.HomologicalComplex", "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Abelian.Basic" ]
Mathlib/AlgebraicTopology/MooreComplex.lean
map
The normalized Moore complex functor, on morphisms.
@[simps] normalizedMooreComplex : SimplicialObject C ⥤ ChainComplex C ℕ where obj := obj map f := map f
def
AlgebraicTopology
[ "Mathlib.Algebra.Homology.HomologicalComplex", "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Abelian.Basic" ]
Mathlib/AlgebraicTopology/MooreComplex.lean
normalizedMooreComplex
The (normalized) Moore complex of a simplicial object `X` in an abelian category `C`. The `n`-th object is intersection of the kernels of `X.δ i : X.obj n ⟶ X.obj (n-1)`, for `i = 1, ..., n`. The differentials are induced from `X.δ 0`, which maps each of these intersections of kernels to the next.
normalizedMooreComplex_objD (X : SimplicialObject C) (n : ℕ) : ((normalizedMooreComplex C).obj X).d (n + 1) n = NormalizedMooreComplex.objD X n := ChainComplex.of_d _ _ (d_squared X) n
theorem
AlgebraicTopology
[ "Mathlib.Algebra.Homology.HomologicalComplex", "Mathlib.AlgebraicTopology.SimplicialObject.Basic", "Mathlib.CategoryTheory.Abelian.Basic" ]
Mathlib/AlgebraicTopology/MooreComplex.lean
normalizedMooreComplex_objD
null
@[nolint unusedArguments] SimplicialThickening (J : Type*) [LinearOrder J] : Type _ := J
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
SimplicialThickening
A type synonym for a linear order `J`, will be equipped with a simplicial category structure.
@[ext] Path {J : Type*} [LinearOrder J] (i j : J) where /-- The underlying subset -/ I : Set J left : i ∈ I := by simp right : j ∈ I := by simp left_le (k : J) (_ : k ∈ I) : i ≤ k := by simp le_right (k : J) (_ : k ∈ I) : k ≤ j := by simp
structure
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
Path
A path from `i` to `j` in a linear order `J` is a subset of the interval `[i, j]` in `J` containing the endpoints.
Path.le {J : Type*} [LinearOrder J] {i j : J} (f : Path i j) : i ≤ j := f.left_le _ f.right
lemma
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
Path.le
null
@[ext] hom_ext {J : Type*} [LinearOrder J] (i j : SimplicialThickening J) (x y : i ⟶ j) (h : ∀ t, t ∈ x.I ↔ t ∈ y.I) : x = y := by apply Path.ext ext apply h
lemma
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
hom_ext
null
@[simps] compFunctor {J : Type*} [LinearOrder J] (i j k : SimplicialThickening J) : (i ⟶ j) × (j ⟶ k) ⥤ (i ⟶ k) where obj x := x.1 ≫ x.2 map f := ⟨⟨Set.union_subset_union f.1.1.1 f.2.1.1⟩⟩
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
compFunctor
Composition of morphisms in `SimplicialThickening J`, as a functor `(i ⟶ j) × (j ⟶ k) ⥤ (i ⟶ k)`
Hom (i j : SimplicialThickening J) : SSet := (nerve (i ⟶ j))
abbrev
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
Hom
The hom simplicial set of the simplicial category structure on `SimplicialThickening J`
id (i : SimplicialThickening J) : 𝟙_ SSet ⟶ Hom i i := ⟨fun _ _ ↦ (Functor.const _).obj (𝟙 _), fun _ _ _ ↦ by simp; rfl⟩
abbrev
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
id
The identity of the simplicial category structure on `SimplicialThickening J`
comp (i j k : SimplicialThickening J) : Hom i j ⊗ Hom j k ⟶ Hom i k := ⟨fun _ x ↦ x.1.prod' x.2 ⋙ compFunctor i j k, fun _ _ _ ↦ by simp; rfl⟩ @[simp]
abbrev
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
comp
The composition of the simplicial category structure on `SimplicialThickening J`
id_comp (i j : SimplicialThickening J) : (λ_ (Hom i j)).inv ≫ id i ▷ Hom i j ≫ comp i i j = 𝟙 (Hom i j) := by aesop @[simp]
lemma
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
id_comp
null
comp_id (i j : SimplicialThickening J) : (ρ_ (Hom i j)).inv ≫ Hom i j ◁ id j ≫ comp i j j = 𝟙 (Hom i j) := by aesop @[simp]
lemma
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
comp_id
null
assoc (i j k l : SimplicialThickening J) : (α_ (Hom i j) (Hom j k) (Hom k l)).inv ≫ comp i j k ▷ Hom k l ≫ comp i k l = Hom i j ◁ comp j k l ≫ comp i j l := by aesop
lemma
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
assoc
null
orderHom {J K : Type*} [LinearOrder J] [LinearOrder K] (f : J →o K) : SimplicialThickening J →o SimplicialThickening K := f
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
orderHom
Auxiliary definition for `SimplicialThickening.functorMap`
noncomputable functorMap {J K : Type u} [LinearOrder J] [LinearOrder K] (f : J →o K) (i j : SimplicialThickening J) : (i ⟶ j) ⥤ ((orderHom f i) ⟶ (orderHom f j)) where obj I := ⟨f '' I.I, Set.mem_image_of_mem f I.left, Set.mem_image_of_mem f I.right, by rintro _ ⟨k, hk, rfl⟩; exact f.monotone (I.left_le k hk), by rintro _ ⟨k, hk, rfl⟩; exact f.monotone (I.le_right k hk)⟩ map f := ⟨⟨Set.image_mono f.1.1⟩⟩
abbrev
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
functorMap
Auxiliary definition for `SimplicialThickening.functor`
@[simps] noncomputable functor {J K : Type u} [LinearOrder J] [LinearOrder K] (f : J →o K) : EnrichedFunctor SSet (SimplicialThickening J) (SimplicialThickening K) where obj := f map i j := nerveMap ((functorMap f i j)) map_id i := by ext simp only [eId, EnrichedCategory.id] exact Functor.ext (by cat_disch) map_comp i j k := by ext simp only [eComp, EnrichedCategory.comp] exact Functor.ext (by cat_disch)
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
functor
The simplicial thickening defines a functor from the category of linear orders to the category of simplicial categories
functor_id (J : Type u) [LinearOrder J] : (functor (OrderHom.id (α := J))) = EnrichedFunctor.id _ _ := by refine EnrichedFunctor.ext _ (fun _ ↦ rfl) fun i j ↦ ?_ ext exact Functor.ext (by cat_disch)
lemma
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
functor_id
null
functor_comp {J K L : Type u} [LinearOrder J] [LinearOrder K] [LinearOrder L] (f : J →o K) (g : K →o L) : functor (g.comp f) = (functor f).comp _ (functor g) := by refine EnrichedFunctor.ext _ (fun _ ↦ rfl) fun i j ↦ ?_ ext exact Functor.ext (by cat_disch)
lemma
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
functor_comp
null
noncomputable SimplicialNerve (C : Type u) [Category.{v} C] [SimplicialCategory C] : SSet.{max u v} where obj n := EnrichedFunctor SSet (SimplicialThickening (ULift (Fin (n.unop.len + 1)))) C map f := (SimplicialThickening.functor f.unop.toOrderHom.uliftMap).comp (E := C) SSet map_id i := by change EnrichedFunctor.comp SSet (SimplicialThickening.functor (OrderHom.id)) = _ rw [SimplicialThickening.functor_id] rfl map_comp f g := by change EnrichedFunctor.comp SSet (SimplicialThickening.functor (f.unop.toOrderHom.uliftMap.comp g.unop.toOrderHom.uliftMap)) = _ rw [SimplicialThickening.functor_comp] rfl
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialCategory.Basic", "Mathlib.AlgebraicTopology.SimplicialSet.Nerve" ]
Mathlib/AlgebraicTopology/SimplicialNerve.lean
SimplicialNerve
The simplicial nerve of a simplicial category `C` is defined as the simplicial set whose `n`-simplices are given by the set of simplicial functors from the simplicial thickening of the linear order `Fin (n + 1)` to `C`
noncomputable TopCat.toSSet : TopCat.{u} ⥤ SSet.{u} := Presheaf.restrictedULiftYoneda.{0} SimplexCategory.toTop.{u}
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.TopologicalSimplex", "Mathlib.CategoryTheory.Limits.Presheaf", "Mathlib.Topology.Category.TopCat.Limits.Basic", "Mathlib.Topology.Category.TopCat.ULift" ]
Mathlib/AlgebraicTopology/SingularSet.lean
TopCat.toSSet
The functor associating the *singular simplicial set* to a topological space. Let `X : TopCat.{u}` be a topological space. Then the singular simplicial set of `X` has as `n`-simplices the continuous maps `ULift.{u} ⦋n⦌.toTop → X`. Here, `⦋n⦌.toTop` is the standard topological `n`-simplex, defined as `{ f : Fin (n+1) → ℝ≥0 // ∑ i, f i = 1 }` with its subspace topology.
TopCat.toSSetObjEquiv (X : TopCat.{u}) (n : SimplexCategoryᵒᵖ) : (toSSet.obj X).obj n ≃ C(n.unop.toTopObj, X) := Equiv.ulift.{0}.trans (ConcreteCategory.homEquiv.trans (Homeomorph.ulift.continuousMapCongr (.refl _)))
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.TopologicalSimplex", "Mathlib.CategoryTheory.Limits.Presheaf", "Mathlib.Topology.Category.TopCat.Limits.Basic", "Mathlib.Topology.Category.TopCat.ULift" ]
Mathlib/AlgebraicTopology/SingularSet.lean
TopCat.toSSetObjEquiv
If `X : TopCat.{u}` and `n : SimplexCategoryᵒᵖ`, then `(toSSet.obj X).obj n` identifies to the type of continuous maps from the standard simplex `n.unop.toTopObj` to `X`.
noncomputable SSet.toTop : SSet.{u} ⥤ TopCat.{u} := stdSimplex.{u}.leftKanExtension SimplexCategory.toTop
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.TopologicalSimplex", "Mathlib.CategoryTheory.Limits.Presheaf", "Mathlib.Topology.Category.TopCat.Limits.Basic", "Mathlib.Topology.Category.TopCat.ULift" ]
Mathlib/AlgebraicTopology/SingularSet.lean
SSet.toTop
The *geometric realization functor* is the left Kan extension of `SimplexCategory.toTop` along the Yoneda embedding. It is left adjoint to `TopCat.toSSet`, as witnessed by `sSetTopAdj`.
noncomputable sSetTopAdj : SSet.toTop.{u} ⊣ TopCat.toSSet.{u} := Presheaf.uliftYonedaAdjunction (SSet.stdSimplex.{u}.leftKanExtension SimplexCategory.toTop) (SSet.stdSimplex.{u}.leftKanExtensionUnit SimplexCategory.toTop)
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.TopologicalSimplex", "Mathlib.CategoryTheory.Limits.Presheaf", "Mathlib.Topology.Category.TopCat.Limits.Basic", "Mathlib.Topology.Category.TopCat.ULift" ]
Mathlib/AlgebraicTopology/SingularSet.lean
sSetTopAdj
Geometric realization is left adjoint to the singular simplicial set construction.
noncomputable SSet.toTopSimplex : SSet.stdSimplex.{u} ⋙ SSet.toTop ≅ SimplexCategory.toTop := Presheaf.isExtensionAlongULiftYoneda _
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.TopologicalSimplex", "Mathlib.CategoryTheory.Limits.Presheaf", "Mathlib.Topology.Category.TopCat.Limits.Basic", "Mathlib.Topology.Category.TopCat.ULift" ]
Mathlib/AlgebraicTopology/SingularSet.lean
SSet.toTopSimplex
The geometric realization of the representable simplicial sets agree with the usual topological simplices.
noncomputable TopCat.toSSetIsoConst (X : TopCat.{u}) [TotallyDisconnectedSpace X] : TopCat.toSSet.obj X ≅ (Functor.const _).obj X := (NatIso.ofComponents (fun n ↦ Equiv.toIso ((TotallyDisconnectedSpace.continuousMapEquivOfConnectedSpace _ X).symm.trans (X.toSSetObjEquiv n).symm))).symm
def
AlgebraicTopology
[ "Mathlib.AlgebraicTopology.SimplicialSet.StdSimplex", "Mathlib.AlgebraicTopology.TopologicalSimplex", "Mathlib.CategoryTheory.Limits.Presheaf", "Mathlib.Topology.Category.TopCat.Limits.Basic", "Mathlib.Topology.Category.TopCat.ULift" ]
Mathlib/AlgebraicTopology/SingularSet.lean
TopCat.toSSetIsoConst
The singular simplicial set of a totally disconnected space is the constant simplicial set.
toTopObj (x : SimplexCategory) := { f : ToType x → ℝ≥0 | ∑ i, f i = 1 }
def
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
toTopObj
The topological simplex associated to `x : SimplexCategory`. This is the object part of the functor `SimplexCategory.toTop`.
@[ext] toTopObj.ext {x : SimplexCategory} (f g : x.toTopObj) : (f : ToType x → ℝ≥0) = g → f = g := Subtype.ext @[simp]
theorem
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
toTopObj.ext
null
toTopObj_zero_apply_zero (f : ⦋0⦌.toTopObj) : f 0 = 1 := by simpa [toType_apply] using show ∑ _, _ = _ from f.2
lemma
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
toTopObj_zero_apply_zero
null
toTopObj_one_add_eq_one (f : ⦋1⦌.toTopObj) : f 0 + f 1 = 1 := by simpa [toType_apply, Finset.sum] using show ∑ _, _ = _ from f.2
lemma
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
toTopObj_one_add_eq_one
null
toTopObj_one_coe_add_coe_eq_one (f : ⦋1⦌.toTopObj) : (f 0 : ℝ) + f 1 = 1 := by norm_cast rw [toTopObj_one_add_eq_one]
lemma
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
toTopObj_one_coe_add_coe_eq_one
null
toTopObjOneHomeo : ⦋1⦌.toTopObj ≃ₜ I where toFun f := ⟨f 0, (f 0).2, toTopObj_one_coe_add_coe_eq_one f ▸ le_add_of_nonneg_right (f 1).2⟩ invFun x := ⟨![toNNReal x, toNNReal (σ x)], show ∑ _, _ = _ by ext; simp [toType_apply, Finset.sum]⟩ left_inv f := by ext i; fin_cases i <;> simp [← toTopObj_one_coe_add_coe_eq_one f] right_inv x := by simp continuous_toFun := .subtype_mk (continuous_subtype_val.comp ((continuous_apply _).comp continuous_subtype_val)) _ continuous_invFun := .subtype_mk (continuous_pi fun i ↦ by fin_cases i <;> dsimp <;> fun_prop) _ open unitInterval in
def
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
toTopObjOneHomeo
The one-dimensional topological simplex is homeomorphic to the unit interval.
toTopMap {x y : SimplexCategory} (f : x ⟶ y) (g : x.toTopObj) : y.toTopObj := ⟨fun i => ∑ j ∈ Finset.univ.filter (f · = i), g j, by simp only [toTopObj, Set.mem_setOf] rw [← Finset.sum_biUnion] · have hg : ∑ i : ToType x, g i = 1 := g.2 convert hg simp [Finset.eq_univ_iff_forall] · convert Set.pairwiseDisjoint_filter _ _ _⟩ open Classical in @[simp]
def
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
toTopMap
A morphism in `SimplexCategory` induces a map on the associated topological spaces.
coe_toTopMap {x y : SimplexCategory} (f : x ⟶ y) (g : x.toTopObj) (i : ToType y) : toTopMap f g i = ∑ j ∈ Finset.univ.filter (f · = i), g j := rfl @[continuity, fun_prop]
theorem
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
coe_toTopMap
null
continuous_toTopMap {x y : SimplexCategory} (f : x ⟶ y) : Continuous (toTopMap f) := by refine Continuous.subtype_mk (continuous_pi fun i => ?_) _ dsimp only [coe_toTopMap] exact continuous_finset_sum _ (fun j _ => (continuous_apply _).comp continuous_subtype_val)
theorem
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
continuous_toTopMap
null
@[simps obj map] toTop₀ : SimplexCategory ⥤ TopCat.{0} where obj x := TopCat.of x.toTopObj map f := TopCat.ofHom ⟨toTopMap f, by fun_prop⟩ map_id := by classical intro Δ ext f simp [Finset.sum_filter] map_comp := fun f g => by classical ext h : 3 dsimp rw [← Finset.sum_biUnion] · apply Finset.sum_congr · exact Finset.ext (fun j => ⟨fun hj => by simpa using hj, fun hj => by simpa using hj⟩) · tauto · apply Set.pairwiseDisjoint_filter
def
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
toTop₀
The functor `SimplexCategory ⥤ TopCat.{0}` associating the topological `n`-simplex to `⦋n⦌ : SimplexCategory`.
@[simps! obj map, pp_with_univ] toTop : SimplexCategory ⥤ TopCat.{u} := toTop₀ ⋙ TopCat.uliftFunctor
def
AlgebraicTopology
[ "Mathlib.Algebra.BigOperators.Ring.Finset", "Mathlib.AlgebraicTopology.SimplexCategory.Basic", "Mathlib.Topology.Category.TopCat.ULift", "Mathlib.Topology.Connected.PathConnected" ]
Mathlib/AlgebraicTopology/TopologicalSimplex.lean
toTop
The functor `SimplexCategory ⥤ TopCat.{u}` associating the topological `n`-simplex to `⦋n⦌ : SimplexCategory`.
ae_differentiableWithinAt_of_mem_real {f : ℝ → ℝ} {s : Set ℝ} (h : LocallyBoundedVariationOn f s) : ∀ᵐ x, x ∈ s → DifferentiableWithinAt ℝ f s x := by obtain ⟨p, q, hp, hq, rfl⟩ : ∃ p q, MonotoneOn p s ∧ MonotoneOn q s ∧ f = p - q := h.exists_monotoneOn_sub_monotoneOn filter_upwards [hp.ae_differentiableWithinAt_of_mem, hq.ae_differentiableWithinAt_of_mem] with x hxp hxq xs exact (hxp xs).sub (hxq xs)
theorem
Analysis
[ "Mathlib.Analysis.Calculus.FDeriv.Add", "Mathlib.Analysis.Calculus.FDeriv.Equiv", "Mathlib.Analysis.Calculus.FDeriv.Prod", "Mathlib.Analysis.Calculus.Monotone", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/BoundedVariation.lean
ae_differentiableWithinAt_of_mem_real
A bounded variation function into `ℝ` is differentiable almost everywhere. Superseded by `ae_differentiableWithinAt_of_mem`.
ae_differentiableWithinAt_of_mem_pi {ι : Type*} [Fintype ι] {f : ℝ → ι → ℝ} {s : Set ℝ} (h : LocallyBoundedVariationOn f s) : ∀ᵐ x, x ∈ s → DifferentiableWithinAt ℝ f s x := by have A : ∀ i : ι, LipschitzWith 1 fun x : ι → ℝ => x i := fun i => LipschitzWith.eval i have : ∀ i : ι, ∀ᵐ x, x ∈ s → DifferentiableWithinAt ℝ (fun x : ℝ => f x i) s x := fun i ↦ by apply ae_differentiableWithinAt_of_mem_real exact LipschitzWith.comp_locallyBoundedVariationOn (A i) h filter_upwards [ae_all_iff.2 this] with x hx xs exact differentiableWithinAt_pi.2 fun i => hx i xs
theorem
Analysis
[ "Mathlib.Analysis.Calculus.FDeriv.Add", "Mathlib.Analysis.Calculus.FDeriv.Equiv", "Mathlib.Analysis.Calculus.FDeriv.Prod", "Mathlib.Analysis.Calculus.Monotone", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/BoundedVariation.lean
ae_differentiableWithinAt_of_mem_pi
A bounded variation function into a finite-dimensional product vector space is differentiable almost everywhere. Superseded by `ae_differentiableWithinAt_of_mem`.
ae_differentiableWithinAt_of_mem {f : ℝ → V} {s : Set ℝ} (h : LocallyBoundedVariationOn f s) : ∀ᵐ x, x ∈ s → DifferentiableWithinAt ℝ f s x := by let A := (Module.Basis.ofVectorSpace ℝ V).equivFun.toContinuousLinearEquiv suffices H : ∀ᵐ x, x ∈ s → DifferentiableWithinAt ℝ (A ∘ f) s x by filter_upwards [H] with x hx xs have : f = (A.symm ∘ A) ∘ f := by simp only [ContinuousLinearEquiv.symm_comp_self, Function.id_comp] rw [this] exact A.symm.differentiableAt.comp_differentiableWithinAt x (hx xs) apply ae_differentiableWithinAt_of_mem_pi exact A.lipschitz.comp_locallyBoundedVariationOn h
theorem
Analysis
[ "Mathlib.Analysis.Calculus.FDeriv.Add", "Mathlib.Analysis.Calculus.FDeriv.Equiv", "Mathlib.Analysis.Calculus.FDeriv.Prod", "Mathlib.Analysis.Calculus.Monotone", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/BoundedVariation.lean
ae_differentiableWithinAt_of_mem
A real function into a finite-dimensional real vector space with bounded variation on a set is differentiable almost everywhere in this set.
ae_differentiableWithinAt {f : ℝ → V} {s : Set ℝ} (h : LocallyBoundedVariationOn f s) (hs : MeasurableSet s) : ∀ᵐ x ∂volume.restrict s, DifferentiableWithinAt ℝ f s x := by rw [ae_restrict_iff' hs] exact h.ae_differentiableWithinAt_of_mem
theorem
Analysis
[ "Mathlib.Analysis.Calculus.FDeriv.Add", "Mathlib.Analysis.Calculus.FDeriv.Equiv", "Mathlib.Analysis.Calculus.FDeriv.Prod", "Mathlib.Analysis.Calculus.Monotone", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/BoundedVariation.lean
ae_differentiableWithinAt
A real function into a finite-dimensional real vector space with bounded variation on a set is differentiable almost everywhere in this set.
ae_differentiableAt {f : ℝ → V} (h : LocallyBoundedVariationOn f univ) : ∀ᵐ x, DifferentiableAt ℝ f x := by filter_upwards [h.ae_differentiableWithinAt_of_mem] with x hx rw [differentiableWithinAt_univ] at hx exact hx (mem_univ _)
theorem
Analysis
[ "Mathlib.Analysis.Calculus.FDeriv.Add", "Mathlib.Analysis.Calculus.FDeriv.Equiv", "Mathlib.Analysis.Calculus.FDeriv.Prod", "Mathlib.Analysis.Calculus.Monotone", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/BoundedVariation.lean
ae_differentiableAt
A real function into a finite-dimensional real vector space with bounded variation is differentiable almost everywhere.
LipschitzOnWith.ae_differentiableWithinAt_of_mem_real {C : ℝ≥0} {f : ℝ → V} {s : Set ℝ} (h : LipschitzOnWith C f s) : ∀ᵐ x, x ∈ s → DifferentiableWithinAt ℝ f s x := h.locallyBoundedVariationOn.ae_differentiableWithinAt_of_mem
theorem
Analysis
[ "Mathlib.Analysis.Calculus.FDeriv.Add", "Mathlib.Analysis.Calculus.FDeriv.Equiv", "Mathlib.Analysis.Calculus.FDeriv.Prod", "Mathlib.Analysis.Calculus.Monotone", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/BoundedVariation.lean
LipschitzOnWith.ae_differentiableWithinAt_of_mem_real
A real function into a finite-dimensional real vector space which is Lipschitz on a set is differentiable almost everywhere in this set. For the general Rademacher theorem assuming that the source space is finite dimensional, see `LipschitzOnWith.ae_differentiableWithinAt_of_mem`.
LipschitzOnWith.ae_differentiableWithinAt_real {C : ℝ≥0} {f : ℝ → V} {s : Set ℝ} (h : LipschitzOnWith C f s) (hs : MeasurableSet s) : ∀ᵐ x ∂volume.restrict s, DifferentiableWithinAt ℝ f s x := h.locallyBoundedVariationOn.ae_differentiableWithinAt hs
theorem
Analysis
[ "Mathlib.Analysis.Calculus.FDeriv.Add", "Mathlib.Analysis.Calculus.FDeriv.Equiv", "Mathlib.Analysis.Calculus.FDeriv.Prod", "Mathlib.Analysis.Calculus.Monotone", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/BoundedVariation.lean
LipschitzOnWith.ae_differentiableWithinAt_real
A real function into a finite-dimensional real vector space which is Lipschitz on a set is differentiable almost everywhere in this set. For the general Rademacher theorem assuming that the source space is finite dimensional, see `LipschitzOnWith.ae_differentiableWithinAt`.
LipschitzWith.ae_differentiableAt_real {C : ℝ≥0} {f : ℝ → V} (h : LipschitzWith C f) : ∀ᵐ x, DifferentiableAt ℝ f x := (h.locallyBoundedVariationOn univ).ae_differentiableAt
theorem
Analysis
[ "Mathlib.Analysis.Calculus.FDeriv.Add", "Mathlib.Analysis.Calculus.FDeriv.Equiv", "Mathlib.Analysis.Calculus.FDeriv.Prod", "Mathlib.Analysis.Calculus.Monotone", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/BoundedVariation.lean
LipschitzWith.ae_differentiableAt_real
A real Lipschitz function into a finite-dimensional real vector space is differentiable almost everywhere. For the general Rademacher theorem assuming that the source space is finite dimensional, see `LipschitzWith.ae_differentiableAt`.
HasConstantSpeedOnWith := ∀ ⦃x⦄ (_ : x ∈ s) ⦃y⦄ (_ : y ∈ s), eVariationOn f (s ∩ Icc x y) = ENNReal.ofReal (l * (y - x)) variable {f s l}
def
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
HasConstantSpeedOnWith
`f` has constant speed `l` on `s` if the variation of `f` on `s ∩ Icc x y` is equal to `l * (y - x)` for any `x y` in `s`.
HasConstantSpeedOnWith.hasLocallyBoundedVariationOn (h : HasConstantSpeedOnWith f s l) : LocallyBoundedVariationOn f s := fun x y hx hy => by simp only [BoundedVariationOn, h hx hy, Ne, ENNReal.ofReal_ne_top, not_false_iff]
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
HasConstantSpeedOnWith.hasLocallyBoundedVariationOn
null
hasConstantSpeedOnWith_of_subsingleton (f : ℝ → E) {s : Set ℝ} (hs : s.Subsingleton) (l : ℝ≥0) : HasConstantSpeedOnWith f s l := by rintro x hx y hy; cases hs hx hy rw [eVariationOn.subsingleton f (fun y hy z hz => hs hy.1 hz.1 : (s ∩ Icc x x).Subsingleton)] simp only [sub_self, mul_zero, ENNReal.ofReal_zero]
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
hasConstantSpeedOnWith_of_subsingleton
null
hasConstantSpeedOnWith_iff_ordered : HasConstantSpeedOnWith f s l ↔ ∀ ⦃x⦄ (_ : x ∈ s) ⦃y⦄ (_ : y ∈ s), x ≤ y → eVariationOn f (s ∩ Icc x y) = ENNReal.ofReal (l * (y - x)) := by refine ⟨fun h x xs y ys _ => h xs ys, fun h x xs y ys => ?_⟩ rcases le_total x y with (xy | yx) · exact h xs ys xy · rw [eVariationOn.subsingleton, ENNReal.ofReal_of_nonpos] · exact mul_nonpos_of_nonneg_of_nonpos l.prop (sub_nonpos_of_le yx) · rintro z ⟨zs, xz, zy⟩ w ⟨ws, xw, wy⟩ cases le_antisymm (zy.trans yx) xz cases le_antisymm (wy.trans yx) xw rfl
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
hasConstantSpeedOnWith_iff_ordered
null
hasConstantSpeedOnWith_iff_variationOnFromTo_eq : HasConstantSpeedOnWith f s l ↔ LocallyBoundedVariationOn f s ∧ ∀ ⦃x⦄ (_ : x ∈ s) ⦃y⦄ (_ : y ∈ s), variationOnFromTo f s x y = l * (y - x) := by constructor · rintro h; refine ⟨h.hasLocallyBoundedVariationOn, fun x xs y ys => ?_⟩ rw [hasConstantSpeedOnWith_iff_ordered] at h rcases le_total x y with (xy | yx) · rw [variationOnFromTo.eq_of_le f s xy, h xs ys xy] exact ENNReal.toReal_ofReal (mul_nonneg l.prop (sub_nonneg.mpr xy)) · rw [variationOnFromTo.eq_of_ge f s yx, h ys xs yx] have := ENNReal.toReal_ofReal (mul_nonneg l.prop (sub_nonneg.mpr yx)) simp_all only [NNReal.val_eq_coe]; ring · rw [hasConstantSpeedOnWith_iff_ordered] rintro h x xs y ys xy rw [← h.2 xs ys, variationOnFromTo.eq_of_le f s xy, ENNReal.ofReal_toReal (h.1 x y xs ys)]
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
hasConstantSpeedOnWith_iff_variationOnFromTo_eq
null
HasConstantSpeedOnWith.union {t : Set ℝ} (hfs : HasConstantSpeedOnWith f s l) (hft : HasConstantSpeedOnWith f t l) {x : ℝ} (hs : IsGreatest s x) (ht : IsLeast t x) : HasConstantSpeedOnWith f (s ∪ t) l := by rw [hasConstantSpeedOnWith_iff_ordered] at hfs hft ⊢ rintro z (zs | zt) y (ys | yt) zy · have : (s ∪ t) ∩ Icc z y = s ∩ Icc z y := by ext w; constructor · rintro ⟨ws | wt, zw, wy⟩ · exact ⟨ws, zw, wy⟩ · exact ⟨(le_antisymm (wy.trans (hs.2 ys)) (ht.2 wt)).symm ▸ hs.1, zw, wy⟩ · rintro ⟨ws, zwy⟩; exact ⟨Or.inl ws, zwy⟩ rw [this, hfs zs ys zy] · have : (s ∪ t) ∩ Icc z y = s ∩ Icc z x ∪ t ∩ Icc x y := by ext w; constructor · rintro ⟨ws | wt, zw, wy⟩ exacts [Or.inl ⟨ws, zw, hs.2 ws⟩, Or.inr ⟨wt, ht.2 wt, wy⟩] · rintro (⟨ws, zw, wx⟩ | ⟨wt, xw, wy⟩) exacts [⟨Or.inl ws, zw, wx.trans (ht.2 yt)⟩, ⟨Or.inr wt, (hs.2 zs).trans xw, wy⟩] rw [this, @eVariationOn.union _ _ _ _ f _ _ x, hfs zs hs.1 (hs.2 zs), hft ht.1 yt (ht.2 yt)] · have q := ENNReal.ofReal_add (mul_nonneg l.prop (sub_nonneg.mpr (hs.2 zs))) (mul_nonneg l.prop (sub_nonneg.mpr (ht.2 yt))) simp only [NNReal.val_eq_coe] at q rw [← q] ring_nf exacts [⟨⟨hs.1, hs.2 zs, le_rfl⟩, fun w ⟨_, _, wx⟩ => wx⟩, ⟨⟨ht.1, le_rfl, ht.2 yt⟩, fun w ⟨_, xw, _⟩ => xw⟩] · cases le_antisymm zy ((hs.2 ys).trans (ht.2 zt)) simp only [Icc_self, sub_self, mul_zero, ENNReal.ofReal_zero] exact eVariationOn.subsingleton _ fun _ ⟨_, uz⟩ _ ⟨_, vz⟩ => uz.trans vz.symm · have : (s ∪ t) ∩ Icc z y = t ∩ Icc z y := by ext w; constructor · rintro ⟨ws | wt, zw, wy⟩ · exact ⟨le_antisymm ((ht.2 zt).trans zw) (hs.2 ws) ▸ ht.1, zw, wy⟩ · exact ⟨wt, zw, wy⟩ · rintro ⟨wt, zwy⟩; exact ⟨Or.inr wt, zwy⟩ rw [this, hft zt yt zy]
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
HasConstantSpeedOnWith.union
null
HasConstantSpeedOnWith.Icc_Icc {x y z : ℝ} (hfs : HasConstantSpeedOnWith f (Icc x y) l) (hft : HasConstantSpeedOnWith f (Icc y z) l) : HasConstantSpeedOnWith f (Icc x z) l := by rcases le_total x y with (xy | yx) · rcases le_total y z with (yz | zy) · rw [← Set.Icc_union_Icc_eq_Icc xy yz] exact hfs.union hft (isGreatest_Icc xy) (isLeast_Icc yz) · rintro u ⟨xu, uz⟩ v ⟨xv, vz⟩ rw [Icc_inter_Icc, sup_of_le_right xu, inf_of_le_right vz, ← hfs ⟨xu, uz.trans zy⟩ ⟨xv, vz.trans zy⟩, Icc_inter_Icc, sup_of_le_right xu, inf_of_le_right (vz.trans zy)] · rintro u ⟨xu, uz⟩ v ⟨xv, vz⟩ rw [Icc_inter_Icc, sup_of_le_right xu, inf_of_le_right vz, ← hft ⟨yx.trans xu, uz⟩ ⟨yx.trans xv, vz⟩, Icc_inter_Icc, sup_of_le_right (yx.trans xu), inf_of_le_right vz]
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
HasConstantSpeedOnWith.Icc_Icc
null
hasConstantSpeedOnWith_zero_iff : HasConstantSpeedOnWith f s 0 ↔ ∀ᵉ (x ∈ s) (y ∈ s), edist (f x) (f y) = 0 := by dsimp [HasConstantSpeedOnWith] simp only [zero_mul, ENNReal.ofReal_zero, ← eVariationOn.eq_zero_iff] constructor · by_contra! obtain ⟨h, hfs⟩ := this simp_rw [ne_eq, eVariationOn.eq_zero_iff] at hfs h push_neg at hfs obtain ⟨x, xs, y, ys, hxy⟩ := hfs rcases le_total x y with (xy | yx) · exact hxy (h xs ys x ⟨xs, le_rfl, xy⟩ y ⟨ys, xy, le_rfl⟩) · rw [edist_comm] at hxy exact hxy (h ys xs y ⟨ys, le_rfl, yx⟩ x ⟨xs, yx, le_rfl⟩) · rintro h x _ y _ refine le_antisymm ?_ zero_le' rw [← h] exact eVariationOn.mono f inter_subset_left
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
hasConstantSpeedOnWith_zero_iff
null
HasConstantSpeedOnWith.ratio {l' : ℝ≥0} (hl' : l' ≠ 0) {φ : ℝ → ℝ} (φm : MonotoneOn φ s) (hfφ : HasConstantSpeedOnWith (f ∘ φ) s l) (hf : HasConstantSpeedOnWith f (φ '' s) l') ⦃x : ℝ⦄ (xs : x ∈ s) : EqOn φ (fun y => l / l' * (y - x) + φ x) s := by rintro y ys rw [← sub_eq_iff_eq_add, mul_comm, ← mul_div_assoc, eq_div_iff (NNReal.coe_ne_zero.mpr hl')] rw [hasConstantSpeedOnWith_iff_variationOnFromTo_eq] at hf rw [hasConstantSpeedOnWith_iff_variationOnFromTo_eq] at hfφ symm calc (y - x) * l = l * (y - x) := by rw [mul_comm] _ = variationOnFromTo (f ∘ φ) s x y := (hfφ.2 xs ys).symm _ = variationOnFromTo f (φ '' s) (φ x) (φ y) := (variationOnFromTo.comp_eq_of_monotoneOn f φ φm xs ys) _ = l' * (φ y - φ x) := (hf.2 ⟨x, xs, rfl⟩ ⟨y, ys, rfl⟩) _ = (φ y - φ x) * l' := by rw [mul_comm]
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
HasConstantSpeedOnWith.ratio
null
HasUnitSpeedOn (f : ℝ → E) (s : Set ℝ) := HasConstantSpeedOnWith f s 1
def
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
HasUnitSpeedOn
`f` has unit speed on `s` if it is linearly parameterized by `l = 1` on `s`.
HasUnitSpeedOn.union {t : Set ℝ} {x : ℝ} (hfs : HasUnitSpeedOn f s) (hft : HasUnitSpeedOn f t) (hs : IsGreatest s x) (ht : IsLeast t x) : HasUnitSpeedOn f (s ∪ t) := HasConstantSpeedOnWith.union hfs hft hs ht
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
HasUnitSpeedOn.union
null
HasUnitSpeedOn.Icc_Icc {x y z : ℝ} (hfs : HasUnitSpeedOn f (Icc x y)) (hft : HasUnitSpeedOn f (Icc y z)) : HasUnitSpeedOn f (Icc x z) := HasConstantSpeedOnWith.Icc_Icc hfs hft
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
HasUnitSpeedOn.Icc_Icc
null
unique_unit_speed {φ : ℝ → ℝ} (φm : MonotoneOn φ s) (hfφ : HasUnitSpeedOn (f ∘ φ) s) (hf : HasUnitSpeedOn f (φ '' s)) ⦃x : ℝ⦄ (xs : x ∈ s) : EqOn φ (fun y => y - x + φ x) s := by dsimp only [HasUnitSpeedOn] at hf hfφ convert HasConstantSpeedOnWith.ratio one_ne_zero φm hfφ hf xs using 3 simp
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
unique_unit_speed
If both `f` and `f ∘ φ` have unit speed (on `t` and `s` respectively) and `φ` monotonically maps `s` onto `t`, then `φ` is just a translation (on `s`).
unique_unit_speed_on_Icc_zero {s t : ℝ} (hs : 0 ≤ s) (ht : 0 ≤ t) {φ : ℝ → ℝ} (φm : MonotoneOn φ <| Icc 0 s) (φst : φ '' Icc 0 s = Icc 0 t) (hfφ : HasUnitSpeedOn (f ∘ φ) (Icc 0 s)) (hf : HasUnitSpeedOn f (Icc 0 t)) : EqOn φ id (Icc 0 s) := by rw [← φst] at hf convert unique_unit_speed φm hfφ hf ⟨le_rfl, hs⟩ using 1 have : φ 0 = 0 := by have hm : 0 ∈ φ '' Icc 0 s := by simp only [φst, ht, mem_Icc, le_refl, and_self] obtain ⟨x, xs, hx⟩ := hm apply le_antisymm ((φm ⟨le_rfl, hs⟩ xs xs.1).trans_eq hx) _ have := φst ▸ mapsTo_image φ (Icc 0 s) exact (mem_Icc.mp (@this 0 (by rw [mem_Icc]; exact ⟨le_rfl, hs⟩))).1 simp only [tsub_zero, this, add_zero] rfl
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
unique_unit_speed_on_Icc_zero
If both `f` and `f ∘ φ` have unit speed (on `Icc 0 t` and `Icc 0 s` respectively) and `φ` monotonically maps `Icc 0 s` onto `Icc 0 t`, then `φ` is the identity on `Icc 0 s`
noncomputable naturalParameterization (f : α → E) (s : Set α) (a : α) : ℝ → E := f ∘ @Function.invFunOn _ _ ⟨a⟩ (variationOnFromTo f s a) s
def
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
naturalParameterization
The natural parameterization of `f` on `s`, which, if `f` has locally bounded variation on `s`, * has unit speed on `s` (by `has_unit_speed_naturalParameterization`). * composed with `variationOnFromTo f s a`, is at distance zero from `f` (by `edist_naturalParameterization_eq_zero`).
edist_naturalParameterization_eq_zero {f : α → E} {s : Set α} (hf : LocallyBoundedVariationOn f s) {a : α} (as : a ∈ s) {b : α} (bs : b ∈ s) : edist (naturalParameterization f s a (variationOnFromTo f s a b)) (f b) = 0 := by dsimp only [naturalParameterization] haveI : Nonempty α := ⟨a⟩ obtain ⟨cs, hc⟩ := Function.invFunOn_pos (b := variationOnFromTo f s a b) ⟨b, bs, rfl⟩ rw [variationOnFromTo.eq_left_iff hf as cs bs] at hc apply variationOnFromTo.edist_zero_of_eq_zero hf cs bs hc
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
edist_naturalParameterization_eq_zero
null
has_unit_speed_naturalParameterization (f : α → E) {s : Set α} (hf : LocallyBoundedVariationOn f s) {a : α} (as : a ∈ s) : HasUnitSpeedOn (naturalParameterization f s a) (variationOnFromTo f s a '' s) := by dsimp only [HasUnitSpeedOn] rw [hasConstantSpeedOnWith_iff_ordered] rintro _ ⟨b, bs, rfl⟩ _ ⟨c, cs, rfl⟩ h rcases le_total c b with (cb | bc) · rw [NNReal.coe_one, one_mul, le_antisymm h (variationOnFromTo.monotoneOn hf as cs bs cb), sub_self, ENNReal.ofReal_zero, Icc_self, eVariationOn.subsingleton] exact fun x hx y hy => hx.2.trans hy.2.symm · rw [NNReal.coe_one, one_mul, sub_eq_add_neg, variationOnFromTo.eq_neg_swap, neg_neg, add_comm, variationOnFromTo.add hf bs as cs, ← variationOnFromTo.eq_neg_swap f] rw [← eVariationOn.comp_inter_Icc_eq_of_monotoneOn (naturalParameterization f s a) _ (variationOnFromTo.monotoneOn hf as) bs cs] rw [@eVariationOn.eq_of_edist_zero_on _ _ _ _ _ f] · rw [variationOnFromTo.eq_of_le _ _ bc, ENNReal.ofReal_toReal (hf b c bs cs)] · rintro x ⟨xs, _, _⟩ exact edist_naturalParameterization_eq_zero hf as xs
theorem
Analysis
[ "Mathlib.Data.Set.Function", "Mathlib.Analysis.RCLike.Basic", "Mathlib.Topology.EMetricSpace.BoundedVariation" ]
Mathlib/Analysis/ConstantSpeed.lean
has_unit_speed_naturalParameterization
null
convolution_integrand_bound_right_of_le_of_subset {C : ℝ} (hC : ∀ i, ‖g i‖ ≤ C) {x t : G} {s u : Set G} (hx : x ∈ s) (hu : -tsupport g + s ⊆ u) : ‖L (f t) (g (x - t))‖ ≤ u.indicator (fun t => ‖L‖ * ‖f t‖ * C) t := by refine le_indicator (f := fun t ↦ ‖L (f t) (g (x - t))‖) (fun t _ => ?_) (fun t ht => ?_) t · apply_rules [L.le_of_opNorm₂_le_of_le, le_rfl] · have : x - t ∉ support g := by refine mt (fun hxt => hu ?_) ht refine ⟨_, Set.neg_mem_neg.mpr (subset_closure hxt), _, hx, ?_⟩ simp only [neg_sub, sub_add_cancel] simp only [notMem_support.mp this, (L _).map_zero, norm_zero, le_rfl]
theorem
Analysis
[ "Mathlib.Analysis.Calculus.ContDiff.Basic", "Mathlib.Analysis.Calculus.ParametricIntegral", "Mathlib.MeasureTheory.Integral.Prod", "Mathlib.MeasureTheory.Function.LocallyIntegrable", "Mathlib.MeasureTheory.Group.Integral", "Mathlib.MeasureTheory.Group.Prod", "Mathlib.MeasureTheory.Integral.IntervalInteg...
Mathlib/Analysis/Convolution.lean
convolution_integrand_bound_right_of_le_of_subset
null
_root_.HasCompactSupport.convolution_integrand_bound_right_of_subset (hcg : HasCompactSupport g) (hg : Continuous g) {x t : G} {s u : Set G} (hx : x ∈ s) (hu : -tsupport g + s ⊆ u) : ‖L (f t) (g (x - t))‖ ≤ u.indicator (fun t => ‖L‖ * ‖f t‖ * ⨆ i, ‖g i‖) t := by refine convolution_integrand_bound_right_of_le_of_subset _ (fun i => ?_) hx hu exact le_ciSup (hg.norm.bddAbove_range_of_hasCompactSupport hcg.norm) _
theorem
Analysis
[ "Mathlib.Analysis.Calculus.ContDiff.Basic", "Mathlib.Analysis.Calculus.ParametricIntegral", "Mathlib.MeasureTheory.Integral.Prod", "Mathlib.MeasureTheory.Function.LocallyIntegrable", "Mathlib.MeasureTheory.Group.Integral", "Mathlib.MeasureTheory.Group.Prod", "Mathlib.MeasureTheory.Integral.IntervalInteg...
Mathlib/Analysis/Convolution.lean
_root_.HasCompactSupport.convolution_integrand_bound_right_of_subset
null
_root_.HasCompactSupport.convolution_integrand_bound_right (hcg : HasCompactSupport g) (hg : Continuous g) {x t : G} {s : Set G} (hx : x ∈ s) : ‖L (f t) (g (x - t))‖ ≤ (-tsupport g + s).indicator (fun t => ‖L‖ * ‖f t‖ * ⨆ i, ‖g i‖) t := hcg.convolution_integrand_bound_right_of_subset L hg hx Subset.rfl
theorem
Analysis
[ "Mathlib.Analysis.Calculus.ContDiff.Basic", "Mathlib.Analysis.Calculus.ParametricIntegral", "Mathlib.MeasureTheory.Integral.Prod", "Mathlib.MeasureTheory.Function.LocallyIntegrable", "Mathlib.MeasureTheory.Group.Integral", "Mathlib.MeasureTheory.Group.Prod", "Mathlib.MeasureTheory.Integral.IntervalInteg...
Mathlib/Analysis/Convolution.lean
_root_.HasCompactSupport.convolution_integrand_bound_right
null