Module: Mathlib.AlgebraicTopology.SimplicialSet.NerveAdjunction

Goal state before:
pp: n : ℕ
X Y : Truncated 2
f₀ : X.obj (op { obj := ⦋0⦌, property := _proof_11 }) → Y.obj (op { obj := ⦋0⦌, property := _proof_11 })
f₁ : X.obj (op { obj := ⦋1⦌, property := _proof_12 }) → Y.obj (op { obj := ⦋1⦌, property := _proof_12 })
hδ₁ :
  ∀ (x : X.obj (op { obj := ⦋1⦌, property := _proof_12 })),
    f₀ ((ConcreteCategory.hom (X.map (δ₂ 1 _proof_11 _proof_13).op)) x) =
      (ConcreteCategory.hom (Y.map (δ₂ 1 _proof_11 _proof_13).op)) (f₁ x)
hδ₀ :
  ∀ (x : X.obj (op { obj := ⦋1⦌, property := _proof_12 })),
    f₀ ((ConcreteCategory.hom (X.map (δ₂ 0 _proof_11 _proof_13).op)) x) =
      (ConcreteCategory.hom (Y.map (δ₂ 0 _proof_11 _proof_13).op)) (f₁ x)
H :
  ∀ (x : X.obj (op { obj := ⦋2⦌, property := _proof_14 })) (y : Y.obj (op { obj := ⦋2⦌, property := _proof_14 })),
    f₁ ((ConcreteCategory.hom (X.map (δ₂ 2 _proof_12 _proof_15).op)) x) =
        (ConcreteCategory.hom (Y.map (δ₂ 2 _proof_12 _proof_15).op)) y →
      f₁ ((ConcreteCategory.hom (X.map (δ₂ 0 _proof_12 _proof_15).op)) x) =
          (ConcreteCategory.hom (Y.map (δ₂ 0 _proof_12 _proof_15).op)) y →
        f₁ ((ConcreteCategory.hom (X.map (δ₂ 1 _proof_12 _proof_15).op)) x) =
          (ConcreteCategory.hom (Y.map (δ₂ 1 _proof_12 _proof_15).op)) y
hσ :
  ∀ (x : X.obj (op { obj := ⦋0⦌, property := _proof_11 })),
    f₁ ((ConcreteCategory.hom (X.map (σ₂ 0 _proof_13 _proof_11).op)) x) =
      (ConcreteCategory.hom (Y.map (σ₂ 0 _proof_13 _proof_11).op)) (f₀ x)
hY : Y.StrictSegal
x : X.obj (op { obj := ⦋2⦌, property := _proof_14 })
⊢ (ConcreteCategory.hom (Y.map (δ₂ 0 δ₂_zero_comp_σ₂_one._proof_4 δ₂_zero_comp_σ₂_one._proof_3).op))
      (f₁ ((ConcreteCategory.hom (X.map (δ₂ 2 _proof_12 _proof_15).op)) x)) =
    (ConcreteCategory.hom (Y.map (δ₂ 1 δ₂_zero_comp_σ₂_one._proof_4 δ₂_zero_comp_σ₂_one._proof_3).op))
      (f₁ ((ConcreteCategory.hom (X.map (δ₂ 0 _proof_12 _proof_15).op)) x))

Tactic:
← hδ₁,

Goal state after:
n : ℕ
X Y : Truncated 2
f₀ : X.obj (op { obj := ⦋0⦌, property := _proof_11 }) → Y.obj (op { obj := ⦋0⦌, property := _proof_11 })
f₁ : X.obj (op { obj := ⦋1⦌, property := _proof_12 }) → Y.obj (op { obj := ⦋1⦌, property := _proof_12 })
hδ₁ :
  ∀ (x : X.obj (op { obj := ⦋1⦌, property := _proof_12 })),
    f₀ ((ConcreteCategory.hom (X.map (δ₂ 1 _proof_11 _proof_13).op)) x) =
      (ConcreteCategory.hom (Y.map (δ₂ 1 _proof_11 _proof_13).op)) (f₁ x)
hδ₀ :
  ∀ (x : X.obj (op { obj := ⦋1⦌, property := _proof_12 })),
    f₀ ((ConcreteCategory.hom (X.map (δ₂ 0 _proof_11 _proof_13).op)) x) =
      (ConcreteCategory.hom (Y.map (δ₂ 0 _proof_11 _proof_13).op)) (f₁ x)
H :
  ∀ (x : X.obj (op { obj := ⦋2⦌, property := _proof_14 })) (y : Y.obj (op { obj := ⦋2⦌, property := _proof_14 })),
    f₁ ((ConcreteCategory.hom (X.map (δ₂ 2 _proof_12 _proof_15).op)) x) =
        (ConcreteCategory.hom (Y.map (δ₂ 2 _proof_12 _proof_15).op)) y →
      f₁ ((ConcreteCategory.hom (X.map (δ₂ 0 _proof_12 _proof_15).op)) x) =
          (ConcreteCategory.hom (Y.map (δ₂ 0 _proof_12 _proof_15).op)) y →
        f₁ ((ConcreteCategory.hom (X.map (δ₂ 1 _proof_12 _proof_15).op)) x) =
          (ConcreteCategory.hom (Y.map (δ₂ 1 _proof_12 _proof_15).op)) y
hσ :
  ∀ (x : X.obj (op { obj := ⦋0⦌, property := _proof_11 })),
    f₁ ((ConcreteCategory.hom (X.map (σ₂ 0 _proof_13 _proof_11).op)) x) =
      (ConcreteCategory.hom (Y.map (σ₂ 0 _proof_13 _proof_11).op)) (f₀ x)
hY : Y.StrictSegal
x : X.obj (op { obj := ⦋2⦌, property := _proof_14 })
⊢ (ConcreteCategory.hom (Y.map (δ₂ 0 δ₂_zero_comp_σ₂_one._proof_4 δ₂_zero_comp_σ₂_one._proof_3).op))
      (f₁ ((ConcreteCategory.hom (X.map (δ₂ 2 _proof_12 _proof_15).op)) x)) =
    f₀
      ((ConcreteCategory.hom (X.map (δ₂ 1 _proof_11 _proof_13).op))
        ((ConcreteCategory.hom (X.map (δ₂ 0 _proof_12 _proof_15).op)) x))