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