C : Type u
inst✝ : Category C
X : SimplicialObject C
n : ℕ
i : Fin (n + 2)
⊢ X.map (SimplexCategory.δ (↑Fin.castSucc i)).op ≫ X.map (SimplexCategory.δ i).op =
    X.map (SimplexCategory.δ (Fin.succ i)).op ≫ X.map (SimplexCategory.δ i).op
C : Type u
inst✝ : Category C
X : SimplicialObject C
n : ℕ
i : Fin (n + 2)
⊢ δ X (↑Fin.castSucc i) ≫ δ X i = δ X (Fin.succ i) ≫ δ X i
dsimp [δ]
no goals
C : Type u
inst✝ : Category C
X : SimplicialObject C
n : ℕ
i : Fin (n + 2)
⊢ X.map (SimplexCategory.δ (↑Fin.castSucc i)).op ≫ X.map (SimplexCategory.δ i).op =
    X.map (SimplexCategory.δ (Fin.succ i)).op ≫ X.map (SimplexCategory.δ i).op
simp only [← X.map_comp, ← op_comp, SimplexCategory.δ_comp_δ_self]