proposition: Lemma join_idPl {x y} : reflect (y `|` x = y) (x <= y).
proof: Proof. exact: (@meet_idPl _ L^d). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)