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