proposition: Lemma muleBr x y z : x \is a fin_num -> y +? - z -> x * (y - z) = x * y - x * z.
proof: Proof. by move=> ? yz; rewrite muleDr ?muleN. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed