Lemma islinv_CDRinv : ∏ (x : X) (Hx0 : x ≠ (0 : X)), (CDRinv x Hx0) * x = 1. Proof. intros x Hx0. apply (pr1 (pr2 (pr2 (pr2 (pr2 (pr2 (pr2 X)))) x Hx0))). Qed.
Require Import UniMath.MoreFoundations.Tactics.