proposition: Lemma ltxI x y z : (x < meet y z) = (x < y) && (x < z).
proof: Proof. by rewrite !ltNge leIx negb_or. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)