proposition: Lemma msetIn a A n : A `&` msetn n a = msetn (minn (A a) n) a.
proof: Proof. by apply/msetP => x; rewrite !msetE; have [->|] := altP eqP; rewrite ?minn0. Qed.
imports: mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop tuple) finmap