mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.AlgebraicTopology.ModelCategory.FundamentalLemma

Goal state before:
pp: case inr
C : Type u_1
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : ModelCategory C
H : Type u_2
inst✝³ : Category.{v_2, u_2} H
L : C ⥤ H
inst✝² : L.IsLocalization (weakEquivalences C)
X Y✝ : C
inst✝¹ : IsCofibrant X
Y : C
inst✝ : IsFibrant Y
h✝¹ : IsCofibrant Y
this : ∀ (X : C) [IsCofibrant X], IsFibrant X → Function.Bijective (rightHomotopyClassToHom L)
h✝ : ¬IsFibrant X
X' : C
i : X ⟶ X'
left✝¹ : Cofibration i
left✝ : WeakEquivalence i
right✝ : IsFibrant X'
⊢ Function.Bijective (rightHomotopyClassToHom L)

Tactic:
have _ := isCofibrant_of_cofibration i

Goal state after:
case inr
C : Type u_1
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : ModelCategory C
H : Type u_2
inst✝³ : Category.{v_2, u_2} H
L : C ⥤ H
inst✝² : L.IsLocalization (weakEquivalences C)
X Y✝ : C
inst✝¹ : IsCofibrant X
Y : C
inst✝ : IsFibrant Y
h✝¹ : IsCofibrant Y
this : ∀ (X : C) [IsCofibrant X], IsFibrant X → Function.Bijective (rightHomotopyClassToHom L)
h✝ : ¬IsFibrant X
X' : C
i : X ⟶ X'
left✝¹ : Cofibration i
left✝ : WeakEquivalence i
right✝ : IsFibrant X'
x✝ : IsCofibrant X'
⊢ Function.Bijective (rightHomotopyClassToHom L)
Module: Mathlib.AlgebraicTopology.ModelCategory.FundamentalLemma

Goal state before:
pp: C : Type u_1
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : ModelCategory C
H : Type u_2
inst✝³ : Category.{v_2, u_2} H
L : C ⥤ H
inst✝² : L.IsLocalization (weakEquivalences C)
X Y : C
inst✝¹ : IsCofibrant X
inst✝ : IsFibrant Y
⊢ Function.Surjective L.map

Tactic:
intro f

Goal state after:
C : Type u_1
inst✝⁵ : Category.{v_1, u_1} C
inst✝⁴ : ModelCategory C
H : Type u_2
inst✝³ : Category.{v_2, u_2} H
L : C ⥤ H
inst✝² : L.IsLocalization (weakEquivalences C)
X Y : C
inst✝¹ : IsCofibrant X
inst✝ : IsFibrant Y
f : L.obj X ⟶ L.obj Y
⊢ ∃ a, L.map a = f
Module: Mathlib.AlgebraicTopology.ModelCategory.BifibrantObjectHomotopy

Goal state before:
pp: C : Type u
inst✝² : Category.{v, u} C
inst✝¹ : ModelCategory C
X₁ X₂ : CofibrantObject C
f : X₁ ⟶ X₂
inst✝ : WeakEquivalence f
⊢ WeakEquivalence (bifibrantResolutionMap f)

Tactic:
rw [weakEquivalence_iff]
  change weakEquivalences _ (CofibrantObject.homMk (bifibrantResolutionMap f).hom)
  rw [← weakEquivalence_iff, ← weakEquivalence_precomp_iff (iBifibrantResolutionObj X₁),
    bifibrantResolutionMap_fac, weakEquivalence_precomp_iff]
  infer_instance

Goal state after:
Module: Mathlib.CategoryTheory.Limits.Types.Multicoequalizer

Goal state before:
pp: case mpr
J : MultispanShape
d : MultispanIndex J (Type u)
c : d.multispan.CoconeTypes
this : ∀ (x : d.multispan.ColimitType), ∃ i a, d.multispan.ιColimitType (WalkingMultispan.right i) a = x
⊢ ((∀ (i₁ i₂ : J.R) (x₁ : d.right i₁) (x₂ : d.right i₂),
        c.ι (WalkingMultispan.right i₁) x₁ = c.ι (WalkingMultispan.right i₂) x₂ →
          d.multispan.ιColimitType (WalkingMultispan.right i₁) x₁ =
            d.multispan.ιColimitType (WalkingMultispan.right i₂) x₂) ∧
      ∀ (x : c.pt), ∃ i a, c.ι (WalkingMultispan.right i) a = x) →
    c.IsColimit

Tactic:
rintro ⟨h₁, h₂⟩
    refine ⟨fun x₁ x₂ h ↦ ?_, fun x ↦ ?_⟩
    · obtain ⟨i₁, a₁, rfl⟩ := this x₁
      obtain ⟨i₂, a₂, rfl⟩ := this x₂
      exact h₁ _ _ _ _ h
    · obtain ⟨i, y, rfl⟩ := h₂ x
      exact ⟨d.multispan.ιColimitType (.right i) y, rfl⟩

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplicialSet.Horn

Goal state before:
pp: n : ℕ
i j : Fin (n + 2)
⊢ stdSimplex.objEquiv.symm (SimplexCategory.δ i) ∈ Λ[n + 1, j].obj (op ⦋n⦌) ↔ i ≠ j

Tactic:
by
  dsimp
  rw [← Subcomplex.ofSimplex_le_iff, ← stdSimplex.face_singleton_compl, face_le_horn_iff]
  simp

Goal state after:
Module: Mathlib.CategoryTheory.Limits.Set

Goal state before:
pp: case hinj
J : Type w
inst✝¹ : Category.{w', w} J
X : Type u
inst✝ : IsFilteredOrEmpty J
F : J ⥤ Set X
i j : J
x : X
hx : x ∈ F.obj i
⊢ ∀ (xj : (fun X ↦ X) ((F ⋙ functorToTypes).obj j)),
    (ConcreteCategory.hom ((functorToTypes.mapCocone (colimitCocone F).cocone).ι.app i)) ⟨x, hx⟩ =
        (ConcreteCategory.hom ((functorToTypes.mapCocone (colimitCocone F).cocone).ι.app j)) xj →
      ∃ k f g,
        (ConcreteCategory.hom ((F ⋙ functorToTypes).map f)) ⟨x, hx⟩ =
          (ConcreteCategory.hom ((F ⋙ functorToTypes).map g)) xj

Tactic:
⟨y, hy⟩

Goal state after:
case hinj
J : Type w
inst✝¹ : Category.{w', w} J
X : Type u
inst✝ : IsFilteredOrEmpty J
F : J ⥤ Set X
i j : J
x : X
hx : x ∈ F.obj i
y : X
hy : y ∈ F.obj j
⊢ (ConcreteCategory.hom ((functorToTypes.mapCocone (colimitCocone F).cocone).ι.app i)) ⟨x, hx⟩ =
      (ConcreteCategory.hom ((functorToTypes.mapCocone (colimitCocone F).cocone).ι.app j)) ⟨y, hy⟩ →
    ∃ k f g,
      (ConcreteCategory.hom ((F ⋙ functorToTypes).map f)) ⟨x, hx⟩ =
        (ConcreteCategory.hom ((F ⋙ functorToTypes).map g)) ⟨y, hy⟩
Module: Mathlib.CategoryTheory.Limits.Types.Pushouts

Goal state before:
pp: X₁ X₂ X₃ X₄ X₅ : Type u
t : X₁ ⟶ X₂
r : X₂ ⟶ X₄
l : X₁ ⟶ X₃
b : X₃ ⟶ X₄
k : X₄ ⟶ X₅
r' : X₂ ⟶ X₅
b' : X₃ ⟶ X₅
h₁ : IsPullback t l r' b'
facr : r ≫ k = r'
facb : b ≫ k = b'
inst✝¹ : Mono r'
inst✝ : Mono k
h₂ : Set.range ⇑(ConcreteCategory.hom r) ⊔ Set.range ⇑(ConcreteCategory.hom b) = Set.univ
H :
  ∀ (x₃ y₃ : X₃),
    x₃ ∉ Set.range ⇑(ConcreteCategory.hom l) →
      y₃ ∉ Set.range ⇑(ConcreteCategory.hom l) → (ConcreteCategory.hom b') x₃ = (ConcreteCategory.hom b') y₃ → x₃ = y₃
φ : pushout t l ⟶ X₄
hφ₁ : pushout.inl t l ≫ φ = r
hφ₂ : pushout.inr t l ≫ φ = b
this✝ : Mono (φ ≫ k)
this : IsIso φ
⊢ IsPushout t l r b

Tactic:
exact IsPushout.of_iso (IsPushout.of_hasPushout t l)
    (Iso.refl _) (Iso.refl _) (Iso.refl _) (asIso φ) (by simp) (by simp)
    (by simpa) (by simpa)

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplicialSet.Skeleton

Goal state before:
pp: X Y : SSet
i : X ⟶ Y
d n : ℕ
y : sigmaStdSimplex i d _⦋n⦌
hy : y ∉ Set.range ⇑(ConcreteCategory.hom ((l i d).app (op ⦋n⦌)))
⊢ ∃ c f, ∃ (_ : Epi f), (ConcreteCategory.hom (c.ιSigmaStdSimplex.app (op ⦋n⦌))) (stdSimplex.objEquiv.symm f) = y

Tactic:
obtain ⟨c, s, rfl⟩ := ιSigmaStdSimplex_jointly_surjective y

Goal state after:
X Y : SSet
i : X ⟶ Y
d n : ℕ
c : Cell i d
s : Δ[d] _⦋n⦌
hy :
  (ConcreteCategory.hom (c.ιSigmaStdSimplex.app (op ⦋n⦌))) s ∉ Set.range ⇑(ConcreteCategory.hom ((l i d).app (op ⦋n⦌)))
⊢ ∃ c_1 f,
    ∃ (_ : Epi f),
      (ConcreteCategory.hom (c_1.ιSigmaStdSimplex.app (op ⦋n⦌))) (stdSimplex.objEquiv.symm f) =
        (ConcreteCategory.hom (c.ιSigmaStdSimplex.app (op ⦋n⦌))) s
Module: Mathlib.AlgebraicTopology.SimplicialSet.HornColimits

Goal state before:
pp: X : SSet
f₀ f₂ f₃ : Δ[2] ⟶ X
h₁₂ : stdSimplex.δ 2 ≫ f₀ = stdSimplex.δ 0 ≫ f₃
h₁₃ : stdSimplex.δ 1 ≫ f₀ = stdSimplex.δ 0 ≫ f₂
h₂₃ : stdSimplex.δ 2 ≫ f₂ = stdSimplex.δ 2 ≫ f₃
⊢ ι₀ ≫ desc f₀ f₂ f₃ h₁₂ h₁₃ h₂₃ = f₀

Tactic:
← cancel_epi (stdSimplex.faceSingletonComplIso.{u} 0).inv,

Goal state after:
X : SSet
f₀ f₂ f₃ : Δ[2] ⟶ X
h₁₂ : stdSimplex.δ 2 ≫ f₀ = stdSimplex.δ 0 ≫ f₃
h₁₃ : stdSimplex.δ 1 ≫ f₀ = stdSimplex.δ 0 ≫ f₂
h₂₃ : stdSimplex.δ 2 ≫ f₂ = stdSimplex.δ 2 ≫ f₃
⊢ (stdSimplex.faceSingletonComplIso 0).inv ≫ ι₀ ≫ desc f₀ f₂ f₃ h₁₂ h₁₃ h₂₃ =
    (stdSimplex.faceSingletonComplIso 0).inv ≫ f₀
Module: Mathlib.AlgebraicTopology.SimplicialSet.Path

Goal state before:
pp: case hᵥ.inr
n : ℕ
X : Truncated (n + 1)
m : ℕ
f g : X.Path (m + 1)
h : ∀ (i : Fin (m + 1)), f.arrow i = g.arrow i
j : Fin (m + 1 + 1)
hl : j = Fin.last (m + 1)
⊢ f.vertex (Fin.last m).succ = g.vertex (Fin.last m).succ

Tactic:
rw [← f.arrow_tgt (Fin.last m), ← g.arrow_tgt (Fin.last m), h]

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplicialSet.HornColimits

Goal state before:
pp: X : SSet
f₀ f₂ f₃ : Δ[2] ⟶ X
h₁₂ : stdSimplex.δ 2 ≫ f₀ = stdSimplex.δ 0 ≫ f₃
h₁₃ : stdSimplex.δ 1 ≫ f₀ = stdSimplex.δ 0 ≫ f₂
h₂₃ : stdSimplex.δ 2 ≫ f₂ = stdSimplex.δ 2 ≫ f₃
⊢ horn.faceι 1 3 ι₃._proof_1 ≫ desc f₀ f₂ f₃ h₁₂ h₁₃ h₂₃ = (stdSimplex.faceSingletonComplIso 3).inv ≫ f₃

Tactic:
exact (horn.isColimit 1).fac _ (.right ⟨3, by simp⟩)

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplicialSet.HornColimits

Goal state before:
pp: X : SSet
f₀ f₁ f₃ : Δ[2] ⟶ X
h₀₂ : stdSimplex.δ 2 ≫ f₁ = stdSimplex.δ 1 ≫ f₃
h₁₂ : stdSimplex.δ 2 ≫ f₀ = stdSimplex.δ 0 ≫ f₃
h₂₃ : stdSimplex.δ 0 ≫ f₀ = stdSimplex.δ 0 ≫ f₁
⊢ ι₀ ≫ desc f₀ f₁ f₃ h₀₂ h₁₂ h₂₃ = f₀

Tactic:
← cancel_epi (stdSimplex.faceSingletonComplIso.{u} 0).inv,

Goal state after:
X : SSet
f₀ f₁ f₃ : Δ[2] ⟶ X
h₀₂ : stdSimplex.δ 2 ≫ f₁ = stdSimplex.δ 1 ≫ f₃
h₁₂ : stdSimplex.δ 2 ≫ f₀ = stdSimplex.δ 0 ≫ f₃
h₂₃ : stdSimplex.δ 0 ≫ f₀ = stdSimplex.δ 0 ≫ f₁
⊢ (stdSimplex.faceSingletonComplIso 0).inv ≫ ι₀ ≫ desc f₀ f₁ f₃ h₀₂ h₁₂ h₂₃ =
    (stdSimplex.faceSingletonComplIso 0).inv ≫ f₀
Module: Mathlib.AlgebraicTopology.SimplicialSet.StrictSegal

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
f : X.Path (n + 1)
i : Fin n
j : Fin (n + 2)
h : j = i.succ.castSucc
⊢ (ConcreteCategory.hom (X.map (mkOfSucc i ≫ δ j).op)) (sx.spineToSimplex f) = sx.spineToDiagonal (f.interval (↑i) 2 ⋯)

Tactic:
mkOfSucc_δ_eq h,

Goal state after:
X : SSet
sx : X.StrictSegal
n : ℕ
f : X.Path (n + 1)
i : Fin n
j : Fin (n + 2)
h : j = i.succ.castSucc
⊢ (ConcreteCategory.hom (X.map (intervalEdge (↑i) 2 ⋯).op)) (sx.spineToSimplex f) =
    sx.spineToDiagonal (f.interval (↑i) 2 ⋯)
Module: Mathlib.AlgebraicTopology.SimplicialSet.StrictSegal

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
f : X.Path (n + 1)
i : Fin n
j : Fin (n + 2)
h : j = i.succ.castSucc
⊢ (ConcreteCategory.hom (X.map (mkOfSucc i ≫ δ j).op)) (sx.spineToSimplex f) = sx.spineToDiagonal (f.interval (↑i) 2 ⋯)

Tactic:
rw [mkOfSucc_δ_eq h, spineToSimplex_edge]

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplicialSet.StrictSegal

Goal state before:
pp: case succ.refine_2.inr
X : SSet
h : (n : ℕ) → X.StrictSegalCore n
n : ℕ
hn : (p : X.Path n) → { s // X.spine n s = p }
p : X.Path (n + 1)
i : Fin n
⊢ (X.spine (n + 1) ((h n).concat (p.arrow 0) ↑(hn (p.interval 1 n ⋯)) ⋯)).arrow i.succ = p.arrow i.succ

Tactic:
· simpa [spine_arrow, ← SimplexCategory.mkOfSucc_δ_gt (j := 0) (i := i) (by simp),
          op_comp, Functor.map_comp_apply, ← SimplicialObject.δ_def, δ₀_concat,
          ← p.arrow_interval 1 n i i.succ (by grind) (by grind)] using
            Path.congr_arrow (hn (p.interval 1 n)).prop i

Goal state after:
Module: Mathlib.CategoryTheory.Enriched.Ordinary.Basic

Goal state before:
pp: V : Type u'
inst✝³ : Category.{v', u'} V
inst✝² : MonoidalCategory V
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : EnrichedOrdinaryCategory V C
X Y Y' Y'' : C
g : Y ⟶ Y'
g' : Y' ⟶ Y''
⊢ (ρ_ (X ⟶[V] Y)).inv ≫
      (X ⟶[V] Y) ◁ (λ_ (𝟙_ V)).inv ≫
        (X ⟶[V] Y) ◁ ((eHomEquiv V) g ⊗ₘ (eHomEquiv V) g') ≫
          (α_ (X ⟶[V] Y) (Y ⟶[V] Y') (Y' ⟶[V] Y'')).inv ≫ (eComp V X Y Y' ▷ Y' ⟶[V] Y'') ≫ eComp V X Y' Y'' =
    (ρ_ (X ⟶[V] Y)).inv ≫
      (X ⟶[V] Y) ◁ (eHomEquiv V) g ≫
        eComp V X Y Y' ≫ (ρ_ (X ⟶[V] Y')).inv ≫ (X ⟶[V] Y') ◁ (eHomEquiv V) g' ≫ eComp V X Y' Y''

Tactic:
tensorHom_def,

Goal state after:
V : Type u'
inst✝³ : Category.{v', u'} V
inst✝² : MonoidalCategory V
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : EnrichedOrdinaryCategory V C
X Y Y' Y'' : C
g : Y ⟶ Y'
g' : Y' ⟶ Y''
⊢ (ρ_ (X ⟶[V] Y)).inv ≫
      (X ⟶[V] Y) ◁ (λ_ (𝟙_ V)).inv ≫
        (X ⟶[V] Y) ◁ ((eHomEquiv V) g ▷ 𝟙_ V ≫ (Y ⟶[V] Y') ◁ (eHomEquiv V) g') ≫
          (α_ (X ⟶[V] Y) (Y ⟶[V] Y') (Y' ⟶[V] Y'')).inv ≫ (eComp V X Y Y' ▷ Y' ⟶[V] Y'') ≫ eComp V X Y' Y'' =
    (ρ_ (X ⟶[V] Y)).inv ≫
      (X ⟶[V] Y) ◁ (eHomEquiv V) g ≫
        eComp V X Y Y' ≫ (ρ_ (X ⟶[V] Y')).inv ≫ (X ⟶[V] Y') ◁ (eHomEquiv V) g' ≫ eComp V X Y' Y''
Module: Mathlib.CategoryTheory.Enriched.Basic

Goal state before:
pp: case inj
V : Type v
inst✝⁷ : Category.{w, v} V
inst✝⁶ : MonoidalCategory V
C✝ : Type u₁
inst✝⁵ : EnrichedCategory V C✝
W : Type v'
inst✝⁴ : Category.{w', v'} W
inst✝³ : MonoidalCategory W
C : Type u₁
inst✝² : EnrichedCategory W C
D : Type u₂
inst✝¹ : EnrichedCategory W D
E : Type u₃
inst✝ : EnrichedCategory W E
F : EnrichedFunctor W C D
X✝ Y✝ Z✝ : ForgetEnrichment W C
f : X✝ ⟶ Y✝
g : Y✝ ⟶ Z✝
⊢ Function.Injective (ForgetEnrichment.homTo W)

Tactic:
intro f

Goal state after:
case inj
V : Type v
inst✝⁷ : Category.{w, v} V
inst✝⁶ : MonoidalCategory V
C✝ : Type u₁
inst✝⁵ : EnrichedCategory V C✝
W : Type v'
inst✝⁴ : Category.{w', v'} W
inst✝³ : MonoidalCategory W
C : Type u₁
inst✝² : EnrichedCategory W C
D : Type u₂
inst✝¹ : EnrichedCategory W D
E : Type u₃
inst✝ : EnrichedCategory W E
F : EnrichedFunctor W C D
X✝ Y✝ Z✝ : ForgetEnrichment W C
f✝ : X✝ ⟶ Y✝
g : Y✝ ⟶ Z✝
f : ForgetEnrichment.of W (F.obj (ForgetEnrichment.to W X✝)) ⟶ ForgetEnrichment.of W (F.obj (ForgetEnrichment.to W Z✝))
⊢ ∀
    ⦃a₂ :
      ForgetEnrichment.of W (F.obj (ForgetEnrichment.to W X✝)) ⟶
        ForgetEnrichment.of W (F.obj (ForgetEnrichment.to W Z✝))⦄,
    ForgetEnrichment.homTo W f = ForgetEnrichment.homTo W a₂ → f = a₂
Module: Mathlib.CategoryTheory.Monoidal.Center

Goal state before:
pp: C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
inst✝ : MonoidalCategory C
X₁ Y₁ X₂ Y₂ : Center C
f : X₁ ⟶ Y₁
g : X₂ ⟶ Y₂
U : C
⊢ (f.f ⊗ₘ g.f) ▷ U ≫ ((Y₁.tensorObj Y₂).snd.β U).hom = ((X₁.tensorObj X₂).snd.β U).hom ≫ U ◁ (f.f ⊗ₘ g.f)

Tactic:
tensorHom_def,

Goal state after:
C : Type u₁
inst✝¹ : Category.{v₁, u₁} C
inst✝ : MonoidalCategory C
X₁ Y₁ X₂ Y₂ : Center C
f : X₁ ⟶ Y₁
g : X₂ ⟶ Y₂
U : C
⊢ (f.f ▷ X₂.fst ≫ Y₁.fst ◁ g.f) ▷ U ≫ ((Y₁.tensorObj Y₂).snd.β U).hom =
    ((X₁.tensorObj X₂).snd.β U).hom ≫ U ◁ (f.f ▷ X₂.fst ≫ Y₁.fst ◁ g.f)
Module: Mathlib.AlgebraicTopology.SimplicialSet.HomotopyCat

Goal state before:
pp: V : Truncated 2
x : V.obj (op { obj := ⦋0⦌, property := OneTruncation₂._proof_1 })
⊢ homMk (Edge.id x) = 𝟙 (mk x)

Tactic:
homMk,

Goal state after:
V : Truncated 2
x : V.obj (op { obj := ⦋0⦌, property := OneTruncation₂._proof_1 })
⊢ (quotientFunctor V).map (Cat.FreeRefl.homMk (Edge.id x)) = 𝟙 (mk x)
Module: Mathlib.AlgebraicTopology.Reedy.Basic

Goal state before:
pp: case neg
C : Type u_1
inst✝⁶ : Category.{v_1, u_1} C
W₁ W₂ : MorphismProperty C
inst✝⁵ : W₁.IsMultiplicative
inst✝⁴ : W₂.IsMultiplicative
α : Type u_2
inst✝³ : LinearOrder α
inst✝² : OrderBot α
inst✝¹ : SuccOrder α
inst✝ : WellFoundedLT α
r : ReedyStructure W₁ W₂ α
X Y : C
f : X ⟶ Y
hf : W₁ f
hf' : ¬MorphismProperty.identities C f
⊢ r.deg Y ≤ r.deg X

Tactic:
exact (r.lt₁ f hf hf').le

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplexCategory.GeneratorsRelations.EpiMono

Goal state before:
pp: case last
n : ℕ
⊢ mk (n + 1) ⟶ mk n

Tactic:
| last =>

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplexCategory.GeneratorsRelations.EpiMono

Goal state before:
pp: case inl.inl
n : ℕ
i : Fin (n + 2)
i' : Fin (n + 3)
h✝ : i.succ ≤ i'
h : i.succ < i'
⊢ δ i' ≫ σ i = 𝟙 (mk (n + 1)) ∨ ∃ j j', δ i' ≫ σ i = σ j ≫ δ j'

Tactic:
obtain ⟨i', rfl⟩ := Fin.eq_succ_of_ne_zero (Fin.ne_zero_of_lt h)
      rw [Fin.succ_lt_succ_iff] at h
      obtain ⟨i, rfl⟩ := Fin.eq_castSucc_of_ne_last (Fin.ne_last_of_lt h)
      exact Or.inr ⟨i, i', by rw [δ_comp_σ_of_gt h]⟩

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplexCategory.ToMkOne

Goal state before:
pp: n : ℕ
⊢ Function.Surjective toMk₁

Tactic:
intro f

Goal state after:
n : ℕ
f : ⦋n⦌ ⟶ ⦋1⦌
⊢ ∃ a, toMk₁ a = f
Module: Mathlib.AlgebraicTopology.SimplicialObject.II

Goal state before:
pp: n : ℕ
x : Fin (n + 2)
⊢ map' OrderHom.id x = x

Tactic:
by
  obtain ⟨x, rfl⟩ | rfl := Fin.eq_castSucc_or_eq_last x
  · rw [map'_eq_castSucc_iff]
    simp
  · simp

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplicialObject.II

Goal state before:
pp: case neg
n : ℕ
i x : Fin (n + 1)
hi : i < x
j : Fin (n + 1 + 1)
hj : j < x.succ
h : j ≤ i.castSucc
⊢ i.predAbove j < x

Tactic:
rw [Fin.predAbove_of_le_castSucc _ _ h, ← Fin.castSucc_lt_castSucc_iff,
            Fin.castSucc_castPred]
          exact lt_of_le_of_lt h hi

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplicialSet.AnodyneExtensions.PairingCore

Goal state before:
pp: X : SSet
A : X.Subcomplex
P : A.Pairing
inst✝ : P.IsProper
s t : ↑P.II
x✝ :
  { dim := (↑s).dim + 1, simplex := ((↑(P.p s)).cast ⋯).simplex } =
    { dim := (↑t).dim + 1, simplex := ((↑(P.p t)).cast ⋯).simplex }
⊢ s = t

Tactic:
apply P.p.injective
    rwa [Subtype.ext_iff, N.ext_iff, SSet.N.ext_iff,
      ← (P.p s).val.cast_eq_self (P.isUniquelyCodimOneFace s).dim_eq,
      ← (P.p t).val.cast_eq_self (P.isUniquelyCodimOneFace t).dim_eq]

Goal state after:
Module: Mathlib.AlgebraicTopology.SimplicialSet.AnodyneExtensions.PairingCore

Goal state before:
pp: X : SSet
A : X.Subcomplex
h : A.PairingCore
⊢ h.pairing.IsRegular ↔ h.IsRegular

Tactic:
by
  refine ⟨fun _ ↦ ?_, fun _ ↦ inferInstance⟩
  have : h.IsProper := by
    rw [← isProper_pairing_iff]
    infer_instance
  constructor
  have := h.pairing.wf
  rw [wellFounded_iff_isEmpty_descending_chain] at this ⊢
  exact ⟨fun ⟨f, hf⟩ ↦ this.false
    ⟨fun n ↦ h.equivII (f n), fun n ↦ by simpa [ancestralRel_iff] using hf n⟩⟩

Goal state after:
Module: Mathlib.CategoryTheory.Presentable.Limits

Goal state before:
pp: C : Type u
inst✝⁴ : Category.{v, u} C
K : Type u'
inst✝³ : Category.{v', u'} K
F : K ⥤ C ⥤ Type w'
c : Cone F
hc : (Y : C) → IsLimit (((evaluation C (Type w')).obj Y).mapCone c)
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
hK : HasCardinalLT (Arrow K) κ
J : Type w
inst✝¹ : SmallCategory J
inst✝ : IsCardinalFiltered J κ
X : J ⥤ C
cX : Cocone X
hF : (k : K) → IsColimit ((F.obj k).mapCocone cX)
x : c.pt.obj cX.pt
this : IsFiltered J
y : ↑(F ⋙ (evaluation C (Type w')).obj cX.pt).sections
hy : (Types.isLimitEquivSections (hc cX.pt)).symm y = x
H : ∀ (k : K), ∃ j y_1, (ConcreteCategory.hom (((F.obj k).mapCocone cX).ι.app j)) y_1 = ↑y k
j : K → J := fun k ↦ ⋯.choose
z : (k : K) → (F.obj k).obj (X.obj (j k)) := fun k ↦ ⋯.choose
hz : ∀ (k : K), (ConcreteCategory.hom ((F.obj k).map (cX.ι.app (j k)))) (z k) = ↑y k
k : K
⊢ (ConcreteCategory.hom ((F.obj k).map (cX.ι.app (j k)))) (z k) =
    (ConcreteCategory.hom
        ((F.obj k).map (X.map (IsCardinalFiltered.toMax j ⋯ k)) ≫
          (F.obj k).map (cX.ι.app (IsCardinalFiltered.max j ⋯))))
      (z k)

Tactic:
← Functor.map_comp,

Goal state after:
C : Type u
inst✝⁴ : Category.{v, u} C
K : Type u'
inst✝³ : Category.{v', u'} K
F : K ⥤ C ⥤ Type w'
c : Cone F
hc : (Y : C) → IsLimit (((evaluation C (Type w')).obj Y).mapCone c)
κ : Cardinal.{w}
inst✝² : Fact κ.IsRegular
hK : HasCardinalLT (Arrow K) κ
J : Type w
inst✝¹ : SmallCategory J
inst✝ : IsCardinalFiltered J κ
X : J ⥤ C
cX : Cocone X
hF : (k : K) → IsColimit ((F.obj k).mapCocone cX)
x : c.pt.obj cX.pt
this : IsFiltered J
y : ↑(F ⋙ (evaluation C (Type w')).obj cX.pt).sections
hy : (Types.isLimitEquivSections (hc cX.pt)).symm y = x
H : ∀ (k : K), ∃ j y_1, (ConcreteCategory.hom (((F.obj k).mapCocone cX).ι.app j)) y_1 = ↑y k
j : K → J := fun k ↦ ⋯.choose
z : (k : K) → (F.obj k).obj (X.obj (j k)) := fun k ↦ ⋯.choose
hz : ∀ (k : K), (ConcreteCategory.hom ((F.obj k).map (cX.ι.app (j k)))) (z k) = ↑y k
k : K
⊢ (ConcreteCategory.hom ((F.obj k).map (cX.ι.app (j k)))) (z k) =
    (ConcreteCategory.hom
        ((F.obj k).map (X.map (IsCardinalFiltered.toMax j ⋯ k) ≫ cX.ι.app (IsCardinalFiltered.max j ⋯))))
      (z k)
Module: Mathlib.AlgebraicTopology.SimplicialObject.ChainHomotopy

Goal state before:
pp: C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : Preadditive C
X Y : SimplicialObject C
f g : X ⟶ Y
H : Homotopy f g
n : ℕ
α : Fin (n + 1) × Fin (n + 2) → (X _⦋n + 1⦌ ⟶ Y _⦋n + 1⦌) := fun x ↦ (-1) ^ (↑x.1 + ↑x.2) • X.δ x.2 ≫ H.h x.1
β : Fin (n + 3) × Fin (n + 2) → (X _⦋n + 1⦌ ⟶ Y _⦋n + 1⦌) := fun x ↦ (-1) ^ (↑x.1 + ↑x.2) • H.h x.2 ≫ Y.δ x.1
h₂ : ∀ (x : Fin (n + 1) × Fin (n + 2)), x.1.castSucc < x.2 → α x = -β (x.2.succ, x.1.castSucc)
S : Finset (Fin (n + 1) × Fin (n + 2)) := {x | x.1.castSucc < x.2}
γ₁ : Fin (n + 1) × Fin (n + 2) → Fin (n + 2 + 1) × Fin (n + 1 + 1) := fun x ↦ (x.2.castSucc, x.1.succ)
γ₂ : Fin (n + 1) × Fin (n + 2) → Fin (n + 2 + 1) × Fin (n + 1 + 1) := fun x ↦ (x.2.succ, x.1.castSucc)
γ₃ : Fin (n + 1) → Fin (n + 1 + 1 + 1) × Fin (n + 1 + 1) := fun i ↦ (i.castSucc.succ, i.succ)
γ₄ : Fin (n + 1) → Fin (n + 1 + 1 + 1) × Fin (n + 1 + 1) := fun i ↦ (i.castSucc.succ, i.castSucc)
hγ₁ : Function.Injective γ₁
hγ₂ : Function.Injective γ₂
hγ₃ : Function.Injective γ₃
hγ₄ : Function.Injective γ₄
eq₁ : H.h 0 ≫ Y.δ 0 = β (0, 0)
eq₂ : H.h (Fin.last (n + 1)) ≫ Y.δ (Fin.last (n + 1 + 1)) = -β (Fin.last (n + 2), Fin.last (n + 1))
eq₃ : ∑ x ∈ Sᶜ, α x = -∑ y ∈ Finset.image γ₁ Sᶜ, β y
⊢ ∑ x ∈ S, α x = ∑ x ∈ Finset.image γ₂ S, -β x

Tactic:
Finset.sum_image hγ₂.injOn

Goal state after:
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : Preadditive C
X Y : SimplicialObject C
f g : X ⟶ Y
H : Homotopy f g
n : ℕ
α : Fin (n + 1) × Fin (n + 2) → (X _⦋n + 1⦌ ⟶ Y _⦋n + 1⦌) := fun x ↦ (-1) ^ (↑x.1 + ↑x.2) • X.δ x.2 ≫ H.h x.1
β : Fin (n + 3) × Fin (n + 2) → (X _⦋n + 1⦌ ⟶ Y _⦋n + 1⦌) := fun x ↦ (-1) ^ (↑x.1 + ↑x.2) • H.h x.2 ≫ Y.δ x.1
h₂ : ∀ (x : Fin (n + 1) × Fin (n + 2)), x.1.castSucc < x.2 → α x = -β (x.2.succ, x.1.castSucc)
S : Finset (Fin (n + 1) × Fin (n + 2)) := {x | x.1.castSucc < x.2}
γ₁ : Fin (n + 1) × Fin (n + 2) → Fin (n + 2 + 1) × Fin (n + 1 + 1) := fun x ↦ (x.2.castSucc, x.1.succ)
γ₂ : Fin (n + 1) × Fin (n + 2) → Fin (n + 2 + 1) × Fin (n + 1 + 1) := fun x ↦ (x.2.succ, x.1.castSucc)
γ₃ : Fin (n + 1) → Fin (n + 1 + 1 + 1) × Fin (n + 1 + 1) := fun i ↦ (i.castSucc.succ, i.succ)
γ₄ : Fin (n + 1) → Fin (n + 1 + 1 + 1) × Fin (n + 1 + 1) := fun i ↦ (i.castSucc.succ, i.castSucc)
hγ₁ : Function.Injective γ₁
hγ₂ : Function.Injective γ₂
hγ₃ : Function.Injective γ₃
hγ₄ : Function.Injective γ₄
eq₁ : H.h 0 ≫ Y.δ 0 = β (0, 0)
eq₂ : H.h (Fin.last (n + 1)) ≫ Y.δ (Fin.last (n + 1 + 1)) = -β (Fin.last (n + 2), Fin.last (n + 1))
eq₃ : ∑ x ∈ Sᶜ, α x = -∑ y ∈ Finset.image γ₁ Sᶜ, β y
⊢ ∑ x ∈ S, α x = ∑ x ∈ S, -β (γ₂ x)
Module: Mathlib.CategoryTheory.ExtremalEpi

Goal state before:
pp: C : Type u
inst✝¹ : Category.{v, u} C
X Y : C
f : X ⟶ Y
inst✝ : StrongEpi f
Z : C
p : X ⟶ Z
i : Z ⟶ Y
fac : p ≫ i = f
x✝ : Mono i
sq : CommSq p f i (𝟙 Y)
⊢ i ≫ sq.lift = 𝟙 Z

Tactic:
simp [← cancel_mono i]

Goal state after:
Module: Mathlib.CategoryTheory.SmallRepresentatives

Goal state before:
pp: κ : Cardinal.{w}
C : Type u
inst✝ : Category.{v, u} C
hC : HasCardinalLT (Arrow C) κ
Ω : Type w := κ.ord.ToType
ι : Arrow C ↪ Ω
h₁ : Cardinal.lift.{w, u} (Cardinal.mk C) ≤ Cardinal.lift.{u, w} (Cardinal.mk Ω)
X Y : C
⊢ Function.Injective fun f ↦ Arrow.mk f

Tactic:
intro f

Goal state after:
κ : Cardinal.{w}
C : Type u
inst✝ : Category.{v, u} C
hC : HasCardinalLT (Arrow C) κ
Ω : Type w := κ.ord.ToType
ι : Arrow C ↪ Ω
h₁ : Cardinal.lift.{w, u} (Cardinal.mk C) ≤ Cardinal.lift.{u, w} (Cardinal.mk Ω)
X Y : C
f : X ⟶ Y
⊢ ∀ ⦃a₂ : X ⟶ Y⦄, (fun f ↦ Arrow.mk f) f = (fun f ↦ Arrow.mk f) a₂ → f = a₂