proposition: Lemma incomparable_leF x y : (x >< y) -> (x <= y) = false.
proof: Proof. by apply: contraNF; rewrite /comparable => ->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)