{A : Type} {x1 x2 : A} (p : x1 = x2) (q : x1 = x1) r : (p^ @ q) @ p = r <~> DPath (fun x : A => x = x) p q r. Proof. apply equiv_concat_l, transport_paths_lr. Defined.
Require Import Basics. Require Import Types.Paths Types.Sigma Types.Forall.