proposition: Lemma meetIB z x y : (z `&` y) `&` (x `\` y) = \bot.
proof: Proof. by rewrite -meetA diffKI meetx0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)