Lemma issymmapSet {X : apSet} : ∏ x y : X, x # y → y # x. Proof. exact (pr1 (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.