proposition: Lemma mpolyOver_mulr_closed : mulr_closed (mpolyOver S).
proof: Proof. split=> [|p q /mpolyOverP Sp /mpolyOverP Sq]. by rewrite mpolyOverC rpred1. apply/mpolyOverP=> i; rewrite mcoeffM rpred_sum //. by move=> j _; apply: rpredM. 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