proposition: Lemma meet_idPr {x y} : reflect (y `&` x = x) (x <= y).
proof: Proof. by rewrite meetC; apply/meet_idPl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)