proposition: Fact anti : antisymmetric le.
proof: Proof. rewrite /le => -[x x'] [y y']/=; case: comparableP => //= eq_xy. by case: _ / eq_xy in y' *; rewrite !tagged_asE => /le_anti ->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)