proposition: Lemma meetUK x y : (x `&` y) `|` y = y.
proof: Proof. by rewrite joinC meetC meetKU. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)