proposition: Lemma mulpK q : (q * d) %/ d = q.
proof: Proof. case/esym/edivpP: (addr0 (q * d)); rewrite // size_poly0 size_poly_gt0. by rewrite -lead_coef_eq0; apply: contraTneq ulcd => ->; rewrite unitr0. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop ssralg poly)