proposition: Lemma map_poly_inj : injective (map_poly f).
proof: Proof. move=> p q eqfpq; apply/eqP; rewrite -subr_eq0 -map_poly_eq0. by rewrite rmorphB /= eqfpq subrr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)