proposition: Lemma npoly_submod_closed : submod_closed poly_of_size.
proof: Proof. split=> [|x p q sp sq]; rewrite qualifE/= ?size_polyC ?eqxx//. rewrite (leq_trans (size_add _ _)) // geq_max. by rewrite (leq_trans (size_scale_leq _ _)). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice fintype tuple) mathcomp(bigop binomial finset finfun ssralg countalg finalg poly polydiv) mathcomp(perm fingroup matrix mxalgebra mxpoly vector countalg)