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