{A B} (e : A <~> B) (f : B <~> A) : f oE e = 1 -> e = f^-1. Proof. intro h. refine ((ecompose_V_ee _ _)^ @ ap (fun fe => f^-1 oE fe) h @ ecompose_e1 _). Defined.
Require Import Basics.Overture Basics.Equivalences Types.Equiv.