{A B} (e : A <~> B) (f : B <~> A) : 1 = f oE e -> e^-1 = f. Proof. intro h. refine ((ecompose_1e _)^ @ ap (fun fe => fe oE e^-1) h @ ecompose_ee_V _ _). Defined.
Require Import Basics.Overture Basics.Equivalences Types.Equiv.