proposition: Lemma meetBx x y z : (x `\` y) `&` z = (x `&` z) `\` y.
proof: Proof. by rewrite ![_ `&` z]meetC meetxB. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)