proposition: Lemma meetxB x y z : x `&` (y `\` z) = (x `&` y) `\` z.
proof: Proof. by rewrite diffIx -{1}[x](joinBI z) meetUl meetIB joinx0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)