proposition: Lemma comm_square_comp' {A B C X Y Z : Type} {k : A -> B} {l : B -> C} {f : A -> X} {g : B -> Y} {h : C -> Z} {i : X -> Y} {j : Y -> Z} (H : i o f == g o k) (K : j o g == h o l) : (j o i) o f == h o (l o k).
proof: Proof. intros x. path_via (j (g (k x))). apply ap, H. Defined.
imports: Basics.Overture Basics.PathGroupoids