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