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