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