proposition: Lemma setDIr A B C : A :\: (B :&: C) = (A :\: B) :|: (A :\: C).
proof: Proof. by rewrite !setDE setCI setIUr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop)