Lemma issymmtightapSet {X : tightapSet} : ∏ x y : X, x ≠ y → y ≠ x. Proof. exact issymmapSet. Qed.
Require Import UniMath.Foundations.Propositions. Require Import UniMath.MoreFoundations.Sets. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.MoreFoundations.DecidablePropositions.