proposition: Lemma msetKIidC A B : A `&` (B `&` A) = B `&` A.
proof: Proof. by rewrite msetICA msetIid. Qed.
imports: mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop tuple) finmap