proposition: Lemma cover_leIxl z x y : z `|` y = \top -> (x `&` z <= y) = (x <= y).
proof: Proof. by rewrite joinC; exact: (@disjoint_lexUl _ 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)