{A B : Type} {f : A -> B} {x1 x2 : A} {y : B} (p : x1 = x2) (q : f x1 = y) (r : f x2 = y) : q = ap f p @ r <~> transport (fun x => f x = y) p q = r. Proof. destruct p; simpl. exact (equiv_concat_r (concat_1p r) q). Defined.
Require Import Basics.Overture Basics.Equivalences Basics.PathGroupoids Basics.Tactics.