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