proposition: Lemma monalgU_is_additive k : additive (mkmalgU k).
proof: Proof. by move=> x1 x2 /=; apply/malgP=> k'; rewrite !mcoeffsE mulrnBl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap