proposition: Lemma map_inj_poly : injective (map_poly f).
proof: Proof. move=> p q /polyP eq_pq; apply/polyP=> i; apply: inj_f. by rewrite -!coef_map_id0 ?eq_pq. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)