Lemma istighttightapSet_rev {X : tightapSet} : ∏ x y : X, x = y → ¬ (x ≠ y). Proof. intros x _ <-. now apply isirrefltightapSet. Qed.
Require Import UniMath.Foundations.Propositions. Require Import UniMath.MoreFoundations.Sets. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.MoreFoundations.DecidablePropositions.