proposition: Lemma msetIUl A B C : (A `|` B) `&` C = (A `&` C) `|` (B `&` C).
proof: Proof. by apply/msetP=> x; rewrite !msetE minn_maxl. Qed.
imports: mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop tuple) finmap