proposition: Lemma add_mpolyC : commutative mpoly_add.
proof: Proof. by move=> p q; apply/mpoly_eqP; rewrite !mpoly_valK addrC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype tuple finfun bigop finset binomial) mathcomp(order fingroup perm ssralg zmodp poly ssrint) mathcomp(matrix vector) mathcomp(bigenough) ssrcomplements freeg