Module: Mathlib.AlgebraicTopology.SimplicialSet.NerveAdjunction

Goal state before:
pp: case «0»
X : Truncated 2
C D : Type u
inst✝¹ : SmallCategory C
inst✝ : SmallCategory D
F : X.HomotopyCategory ⥤ C
y : ((truncation 2).obj (nerve C)).obj (op { obj := ⦋2⦌, property := _proof_14 })
h' :
  ∀ {a b : X.obj (op { obj := ⦋0⦌, property := ⋯ })} (e : Edge a b),
    ComposableArrows.mk₁ (F.map (homMk (Edge.mk' e.edge))) = ComposableArrows.mk₁ (F.map (homMk e))
x₀ x₁ x₂ : X.obj (op { obj := ⦋0⦌, property := Edge._proof_1 })
e₀₁ : Edge x₀ x₁
e₁₂ : Edge x₁ x₂
e₀₂ : Edge x₀ x₂
h : e₀₁.CompStruct e₁₂ e₀₂
h₂ :
  ComposableArrows.mk₁ (F.map (homMk e₀₁)) =
    (ConcreteCategory.hom (((truncation 2).obj (nerve C)).map (δ₂ 2 _proof_12 _proof_15).op)) y
h₀ :
  ComposableArrows.mk₁ (F.map (homMk e₁₂)) =
    (ConcreteCategory.hom (((truncation 2).obj (nerve C)).map (δ₂ 0 _proof_12 _proof_15).op)) y
⊢ (((truncation 2).obj (nerve C)).spine 2 _proof_14
          (ComposableArrows.mk₂ (F.map (homMk e₀₁)) (F.map (homMk e₁₂)))).arrow
      ((fun i ↦ i) ⟨0, ⋯⟩) =
    (((truncation 2).obj (nerve C)).spine 2 _proof_14 y).arrow ((fun i ↦ i) ⟨0, ⋯⟩)

pp: case «1»
X : Truncated 2
C D : Type u
inst✝¹ : SmallCategory C
inst✝ : SmallCategory D
F : X.HomotopyCategory ⥤ C
y : ((truncation 2).obj (nerve C)).obj (op { obj := ⦋2⦌, property := _proof_14 })
h' :
  ∀ {a b : X.obj (op { obj := ⦋0⦌, property := ⋯ })} (e : Edge a b),
    ComposableArrows.mk₁ (F.map (homMk (Edge.mk' e.edge))) = ComposableArrows.mk₁ (F.map (homMk e))
x₀ x₁ x₂ : X.obj (op { obj := ⦋0⦌, property := Edge._proof_1 })
e₀₁ : Edge x₀ x₁
e₁₂ : Edge x₁ x₂
e₀₂ : Edge x₀ x₂
h : e₀₁.CompStruct e₁₂ e₀₂
h₂ :
  ComposableArrows.mk₁ (F.map (homMk e₀₁)) =
    (ConcreteCategory.hom (((truncation 2).obj (nerve C)).map (δ₂ 2 _proof_12 _proof_15).op)) y
h₀ :
  ComposableArrows.mk₁ (F.map (homMk e₁₂)) =
    (ConcreteCategory.hom (((truncation 2).obj (nerve C)).map (δ₂ 0 _proof_12 _proof_15).op)) y
⊢ (((truncation 2).obj (nerve C)).spine 2 _proof_14
          (ComposableArrows.mk₂ (F.map (homMk e₀₁)) (F.map (homMk e₁₂)))).arrow
      ((fun i ↦ i) ⟨1, ⋯⟩) =
    (((truncation 2).obj (nerve C)).spine 2 _proof_14 y).arrow ((fun i ↦ i) ⟨1, ⋯⟩)

Tactic:
· dsimp
          simp only [SimplexCategory.mkOfSucc_zero_eq_δ, ← h₂]
          apply nerve.δ₂_mk₂_eq

Goal state after:
case «1»
X : Truncated 2
C D : Type u
inst✝¹ : SmallCategory C
inst✝ : SmallCategory D
F : X.HomotopyCategory ⥤ C
y : ((truncation 2).obj (nerve C)).obj (op { obj := ⦋2⦌, property := _proof_14 })
h' :
  ∀ {a b : X.obj (op { obj := ⦋0⦌, property := ⋯ })} (e : Edge a b),
    ComposableArrows.mk₁ (F.map (homMk (Edge.mk' e.edge))) = ComposableArrows.mk₁ (F.map (homMk e))
x₀ x₁ x₂ : X.obj (op { obj := ⦋0⦌, property := Edge._proof_1 })
e₀₁ : Edge x₀ x₁
e₁₂ : Edge x₁ x₂
e₀₂ : Edge x₀ x₂
h : e₀₁.CompStruct e₁₂ e₀₂
h₂ :
  ComposableArrows.mk₁ (F.map (homMk e₀₁)) =
    (ConcreteCategory.hom (((truncation 2).obj (nerve C)).map (δ₂ 2 _proof_12 _proof_15).op)) y
h₀ :
  ComposableArrows.mk₁ (F.map (homMk e₁₂)) =
    (ConcreteCategory.hom (((truncation 2).obj (nerve C)).map (δ₂ 0 _proof_12 _proof_15).op)) y
⊢ (((truncation 2).obj (nerve C)).spine 2 _proof_14
          (ComposableArrows.mk₂ (F.map (homMk e₀₁)) (F.map (homMk e₁₂)))).arrow
      ((fun i ↦ i) ⟨1, ⋯⟩) =
    (((truncation 2).obj (nerve C)).spine 2 _proof_14 y).arrow ((fun i ↦ i) ⟨1, ⋯⟩)