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