proposition: Lemma issymmtightapSet {X : tightapSet} : ∏ x y : X, x ≠ y -> y ≠ x.
proof: Proof. exact issymmapSet. Qed.
imports: UniMath.Algebra.BinaryOperations UniMath.Foundations.Propositions UniMath.MoreFoundations.Sets UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.DecidablePropositions