Lemma israpbinop_op : ∏ x y y' : X, op x y ≠ op x y' → y ≠ y'. Proof. intros x y y'. now apply (pr2 (pr2 (pr2 X))). Qed.
Require Import UniMath.Foundations.Propositions. Require Import UniMath.MoreFoundations.Sets. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.MoreFoundations.DecidablePropositions.