mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.CategoryTheory.Types.Monomorphisms

Goal state before:
pp: J : Type u'
x✝¹ : Category.{v', u'} J
x✝ : IsFiltered J
F₁ F₂ : J ⥤ Type u
c₁ : Cocone F₁
c₂ : Cocone F₂
hc₁ : IsColimit c₁
hc₂ : IsColimit c₂
f : F₁ ⟶ F₂
hf : (monomorphisms (Type u)).functorCategory J f
φ : c₁.pt ⟶ c₂.pt
hφ : ∀ (j : J), c₁.ι.app j ≫ φ = f.app j ≫ c₂.ι.app j
⊢ monomorphisms (Type u) φ

Tactic:
by
    simp only [functorCategory, monomorphisms.iff, mono_iff_injective] at hf ⊢
    replace hφ (j : J) := congr_hom (hφ j)
    simp only [Functor.const_obj_obj, comp_apply] at hφ
    intro x₁ y₁ h
    obtain ⟨j, x₁, y₁, rfl, rfl⟩ : ∃ (j : J) (x₁' y₁' : F₁.obj j),
        x₁ = c₁.ι.app j x₁' ∧ y₁ = c₁.ι.app j y₁' := by
      obtain ⟨j, x₁, rfl⟩ := Types.jointly_surjective_of_isColimit hc₁ x₁
      obtain ⟨l, y₁, rfl⟩ := Types.jointly_surjective_of_isColimit hc₁ y₁
      exact ⟨_,  _, _, congr_hom (c₁.w (IsFiltered.leftToMax j l)).symm _,
        congr_hom (c₁.w (IsFiltered.rightToMax j l)).symm _⟩
    simp only [Functor.const_obj_obj, hφ] at h
    obtain ⟨k, α, hk⟩ := (Types.FilteredColimit.isColimit_eq_iff' hc₂ _ _).1 h
    simp only [← NatTrans.naturality_apply] at hk
    rw [← c₁.w α, comp_apply, comp_apply, hf _ hk]

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

Goal state before:
pp: n : ℕ
i : Fin (n + 1)
⊢ ⨆ i_1, stdSimplex.face {↑i_1}ᶜ = Λ[n, i]

Tactic:
rw [horn_eq_iSup]

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

Goal state before:
pp: n : ℕ
X Y : Truncated (n + 1)
inst✝ : Y.IsStrictSegal
f g : X ⟶ Y
h :
  ∀ (x : X.obj (op { obj := ⦋1⦌, property := ⋯ })),
    (ConcreteCategory.hom (f.app (op { obj := ⦋1⦌, property := ⋯ }))) x =
      (ConcreteCategory.hom (g.app (op { obj := ⦋1⦌, property := ⋯ }))) x
m : SimplexCategory
hm : m.len ≤ n + 1
x : X.obj (op { obj := m, property := hm })
⊢ (ConcreteCategory.hom (f.app (op { obj := m, property := hm }))).toFun x =
    (ConcreteCategory.hom (g.app (op { obj := m, property := hm }))).toFun x

Tactic:
induction m using SimplexCategory.rec with

Goal state after:
case mk
n : ℕ
X Y : Truncated (n + 1)
inst✝ : Y.IsStrictSegal
f g : X ⟶ Y
h :
  ∀ (x : X.obj (op { obj := ⦋1⦌, property := ⋯ })),
    (ConcreteCategory.hom (f.app (op { obj := ⦋1⦌, property := ⋯ }))) x =
      (ConcreteCategory.hom (g.app (op { obj := ⦋1⦌, property := ⋯ }))) x
m : ℕ
hm : ⦋m⦌.len ≤ n + 1
x : X.obj (op { obj := ⦋m⦌, property := hm })
⊢ (ConcreteCategory.hom (f.app (op { obj := ⦋m⦌, property := hm }))).toFun x =
    (ConcreteCategory.hom (g.app (op { obj := ⦋m⦌, property := hm }))).toFun x
Module: Mathlib.AlgebraicTopology.Quasicategory.StrictSegal

Goal state before:
pp: X : SSet
sx : X.StrictSegal
i : Fin (0 + 3)
σ₀ : Λ[0 + 2, i].toSSet ⟶ X
h₀ : 0 < i
hₙ : i < Fin.last (0 + 2)
j : Fin (0 + 3)
hj : j ≠ i
k : Fin (0 + 1)
ksucc : Fin (0 + 1 + 1 + 1) := k.succ.castSucc
heq : j = ksucc
⊢ k = 0

Tactic:
omega

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

Goal state before:
pp: X : SSet
n : ℕ
Δ : X _⦋n⦌
m : ℕ
φ : ⦋m⦌ ⟶ ⦋n⦌
i : Fin (m + 1)
⊢ n ≤ max m n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
n : ℕ
Δ : X _⦋n⦌
m : ℕ
φ : ⦋m⦌ ⟶ ⦋n⦌
i : Fin (m + 1)
⊢ m ≤ max m n + 1

Tactic:
omega

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

Goal state before:
pp: V : Type v
inst✝² : Category.{w, v} V
inst✝¹ : MonoidalCategory V
C : Type u₁
inst✝ : EnrichedCategory V C
W X Y Z : C
⊢ (α_ (W ⟶[V] X) (X ⟶[V] Y) (Y ⟶[V] Z)).hom ≫
      (α_ (W ⟶[V] X) (X ⟶[V] Y) (Y ⟶[V] Z)).inv ≫ (eComp V W X Y ▷ Y ⟶[V] Z) ≫ eComp V W Y Z =
    (eComp V W X Y ▷ Y ⟶[V] Z) ≫ eComp V W Y Z

Tactic:
Iso.hom_inv_id_assoc

Goal state after:
V : Type v
inst✝² : Category.{w, v} V
inst✝¹ : MonoidalCategory V
C : Type u₁
inst✝ : EnrichedCategory V C
W X Y Z : C
⊢ (eComp V W X Y ▷ Y ⟶[V] Z) ≫ eComp V W Y Z = (eComp V W X Y ▷ Y ⟶[V] Z) ≫ eComp V W Y Z
Module: Mathlib.AlgebraicTopology.SimplicialSet.Monoidal

Goal state before:
pp: X Y : SSet
S : X.Subcomplex
T : Y.Subcomplex
n : SimplexCategoryᵒᵖ
x : Y.obj n
y : X.obj n
⊢ (x, y) ∈ ((S.unionProd T).preimage (β_ Y X).hom).obj n ↔ (x, y) ∈ (T.unionProd S).obj n

Tactic:
simp only [mem_unionProd_iff, preimage_obj, Monoidal.tensorObj_obj,
    dsimp% Set.mem_preimage (f := (β_ Y X).hom.app n)]

Goal state after:
X Y : SSet
S : X.Subcomplex
T : Y.Subcomplex
n : SimplexCategoryᵒᵖ
x : Y.obj n
y : X.obj n
⊢ ((ConcreteCategory.hom ((β_ Y X).hom.app n)) (x, y)).2 ∈ T.obj n ∨
      ((ConcreteCategory.hom ((β_ Y X).hom.app n)) (x, y)).1 ∈ S.obj n ↔
    y ∈ S.obj n ∨ x ∈ T.obj n
Module: Mathlib.AlgebraicTopology.SimplicialSet.HomotopyCat

Goal state before:
pp: C : Type u
inst✝ : Category.{v, u} C
V : Cᵒᵖ ⥤ Type w
X Y Z : C
α : X ⟶ Y
β : Y ⟶ Z
γ : X ⟶ Z
φ : (fun X ↦ X) (V.obj (op Z))
⊢ α ≫ β = γ →
    (ConcreteCategory.hom (V.map α.op)) ((ConcreteCategory.hom (V.map β.op)) φ) = (ConcreteCategory.hom (V.map γ.op)) φ

Tactic:
rintro rfl
  simp

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
⊢ i < n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
⊢ i + k < n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
⊢ j < n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
⊢ i + k ≤ j

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
⊢ i + k < n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
⊢ j < n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
⊢ i + k ≤ j

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
α₀ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯) lift._proof_3
⊢ i < n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
α₀ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯) lift._proof_3
⊢ j < n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
α₀ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯) lift._proof_3
α₁ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) lift._proof_3
⊢ i < n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
α₀ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯) lift._proof_3
α₁ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) lift._proof_3
⊢ i + k < n + 1

Tactic:
omega

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
α₀ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯) lift._proof_3
α₁ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) lift._proof_3
α₂ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⋯) lift._proof_3
⊢ (α.hom ≫ (inclusion 2).op.map (Hom.tr (mkOfSucc 1) ⋯ ⋯).op).unop = α₀.hom.unop

Tactic:
by ext x; fin_cases x <;> rfl

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
α₀ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯) lift._proof_3
α₁ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) lift._proof_3
α₂ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⋯) lift._proof_3
β₀ : α ⟶ α₀ := homMk (Hom.tr (mkOfSucc 1) ⋯ ⋯).op ⋯
⊢ (α.hom ≫ (inclusion 2).op.map (Hom.tr (SimplexCategory.δ 1) ⋯ ⋯).op).unop = α₁.hom.unop

Tactic:
by ext x; fin_cases x <;> rfl

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
α₀ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯) lift._proof_3
α₁ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) lift._proof_3
α₂ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⋯) lift._proof_3
β₀ : α ⟶ α₀ := homMk (Hom.tr (mkOfSucc 1) ⋯ ⋯).op ⋯
β₁ : α ⟶ α₁ := homMk (Hom.tr (SimplexCategory.δ 1) ⋯ ⋯).op ⋯
⊢ (α.hom ≫ (inclusion 2).op.map (Hom.tr (mkOfSucc 0) ⋯ ⋯).op).unop = α₂.hom.unop

Tactic:
by ext x; fin_cases x <;> rfl

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
α₀ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯) lift._proof_3
α₁ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) lift._proof_3
α₂ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⋯) lift._proof_3
β₀ : α ⟶ α₀ := homMk (Hom.tr (mkOfSucc 1) ⋯ ⋯).op ⋯
β₁ : α ⟶ α₁ := homMk (Hom.tr (SimplexCategory.δ 1) ⋯ ⋯).op ⋯
β₂ : α ⟶ α₂ := homMk (Hom.tr (mkOfSucc 0) ⋯ ⋯).op ⋯
h₀ : (ConcreteCategory.hom (X.map α₀.hom)) (lift sx s x) = (ConcreteCategory.hom (s.π.app α₀)) x
h₂ : (ConcreteCategory.hom (X.map α₂.hom)) (lift sx s x) = (ConcreteCategory.hom (s.π.app α₂)) x
t : Fin (1 + 1)
⊢ (α.hom ≫ (mkOfSucc 0).op).unop = α₂.hom.unop

Tactic:
by ext x; fin_cases x <;> rfl

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

Goal state before:
pp: X : SSet
sx : X.StrictSegal
n : ℕ
s : Cone (proj (op ⦋n⦌) (inclusion 2).op ⋙ (inclusion 2).op ⋙ X)
x : s.pt
k : ℕ
hk :
  ∀ (i j : ℕ) (hij : i ≤ j) (hj : j ≤ n),
    i + k = j →
      (ConcreteCategory.hom (X.map (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij).op)) (lift sx s x) =
        (ConcreteCategory.hom (s.π.app (strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) fac_aux₁._proof_1))) x
i j : ℕ
hij : i ≤ j
hj : j ≤ n
hik : i + (k + 1) = j
α : StructuredArrow (op ⦋n⦌) (inclusion 2).op :=
  strArrowMk₂ (mkOfLeComp ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯ ⋯) fac_aux₂._proof_1_10
α₀ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i + k, ⋯⟩ ⟨j, ⋯⟩ ⋯) lift._proof_3
α₁ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨j, ⋯⟩ hij) lift._proof_3
α₂ : StructuredArrow (op ⦋n⦌) (inclusion 2).op := strArrowMk₂ (mkOfLe ⟨i, ⋯⟩ ⟨i + k, ⋯⟩ ⋯) lift._proof_3
β₀ : α ⟶ α₀ := homMk (Hom.tr (mkOfSucc 1) ⋯ ⋯).op ⋯
β₁ : α ⟶ α₁ := homMk (Hom.tr (SimplexCategory.δ 1) ⋯ ⋯).op ⋯
β₂ : α ⟶ α₂ := homMk (Hom.tr (mkOfSucc 0) ⋯ ⋯).op ⋯
h₀ : (ConcreteCategory.hom (X.map α₀.hom)) (lift sx s x) = (ConcreteCategory.hom (s.π.app α₀)) x
h₂ : (ConcreteCategory.hom (X.map α₂.hom)) (lift sx s x) = (ConcreteCategory.hom (s.π.app α₂)) x
t : Fin (1 + 1)
⊢ (α.hom ≫ (mkOfSucc 1).op).unop = α₀.hom.unop

Tactic:
by ext x; fin_cases x <;> rfl

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

Goal state before:
pp: m : ℕ
L : List ℕ
hL : IsAdmissible m L
j : ℕ
hj₁ : j < m + L.length
hj₂ : simplicialEvalσ L j = simplicialEvalσ L (j + 1)
⊢ j ∈ L

Tactic:
by
  induction L generalizing m with
  | nil => grind
  | cons a L h_rec =>
    have := simplicialEvalσ_monotone L (a := a + 1)
    rcases lt_trichotomy j a with h | h | h <;> grind

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

Goal state before:
pp: case neg
n : ℕ
i : Fin (n + 2)
j : Fin (n + 1)
h : i ≤ j.castSucc
k : Fin (⦋n + 1⦌.len + 1)
hk : i ≤ k
⊢ (ConcreteCategory.hom (toMk₁ i)) (j.predAbove k) = (ConcreteCategory.hom (toMk₁ i.castSucc)) k

Tactic:
dsimp
    rw [toMk₁_of_le_castSucc, toMk₁_of_le_castSucc _ _ (by simpa)]
    by_cases hk' : k ≤ j.castSucc
    · rwa [Fin.predAbove_of_le_castSucc _ _ hk', Fin.castSucc_castPred]
    · grind [Fin.predAbove]

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

Goal state before:
pp: case pos
n : ℕ
i x : Fin (n + 2)
hx : x ≤ i
⊢ map' i.succAboveOrderEmb.toOrderHom x.castSucc = i.predAbove x.castSucc

Tactic:
Fin.predAbove_of_le_castSucc _ _ (by simpa),

Goal state after:
case pos
n : ℕ
i x : Fin (n + 2)
hx : x ≤ i
⊢ map' i.succAboveOrderEmb.toOrderHom x.castSucc = x.castSucc.castPred ⋯
Module: Mathlib.AlgebraicTopology.SimplicialSet.ProdStdSimplex

Goal state before:
pp: p q n : ℕ
hn : p + q + 1 ≤ n
⊢ (Δ[p] ⊗ Δ[q]).degenerate n = ⊤

Tactic:
ext x
    simp only [Set.top_eq_univ, Set.mem_univ, iff_true]
    by_contra hx
    rw [← mem_nonDegenerate_iff_notMem_degenerate,
      nonDegenerate_iff_strictMono_objEquiv,
      ← strictMono_orderHomOfSimplex_iff _ rfl] at hx
    replace hx := Fintype.card_le_of_injective _ hx.injective
    simp only [Fintype.card_fin, add_le_add_iff_right] at hx
    lia

Goal state after:
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 : Fin (n + 1) × Fin (n + 2)
hx : x ∈ S
⊢ (-1) ^ (↑x.1 + ↑x.2) • X.δ x.2 ≫ H.h x.1 = -((-1) ^ (↑x.2 + 1 + ↑x.1) • H.h x.1.castSucc ≫ Y.δ x.2.succ)

Tactic:
simp only [← H.h_castSucc_comp_δ_succ_of_lt x.2 x.1 (by simpa [S] using hx),
      pow_add, pow_one, mul_neg, mul_one, neg_mul, neg_smul, neg_neg]

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 : Fin (n + 1) × Fin (n + 2)
hx : x ∈ S
⊢ ((-1) ^ ↑x.1 * (-1) ^ ↑x.2) • H.h x.1.castSucc ≫ Y.δ x.2.succ =
    ((-1) ^ ↑x.2 * (-1) ^ ↑x.1) • H.h x.1.castSucc ≫ Y.δ x.2.succ
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
⊢ IsIso i

Tactic:
by
    have sq : CommSq p f i (𝟙 Y) := { }
    exact ⟨sq.lift, by simp [← cancel_mono i], by simp⟩

Goal state after:
Module: Mathlib.CategoryTheory.ObjectProperty.ColimitsCardinalClosure

Goal state before:
pp: C : Type u
inst✝ : Category.{v, u} C
P : ObjectProperty C
κ : Cardinal.{w}
⊢ (P.colimitsCardinalClosure κ).IsClosedUnderIsomorphisms

Tactic:
dsimp [colimitsCardinalClosure]
  infer_instance

Goal state after: