proposition: Lemma istighttightapSet_rev {X : tightapSet} : ∏ x y : X, x = y -> ¬ (x ≠ y).
proof: Proof. intros x _ <-. now apply isirrefltightapSet. Qed.
imports: UniMath.Algebra.BinaryOperations UniMath.Foundations.Propositions UniMath.MoreFoundations.Sets UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.DecidablePropositions