{A B : Type} {f : A -> B} {g : B -> A} {x1 x2 : A} (p : x1 = x2) (q : g (f x1) = x1) : transport (fun x => g (f x) = x) p q = (ap g (ap f p))^ @ q @ p. Proof. destruct p; simpl. exact ((concat_1p q)^ @ (concat_p1 (1 @ q))^). Defined.
Require Import Basics.Overture Basics.Equivalences Basics.PathGroupoids Basics.Tactics.