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