proposition: Lemma lead_coef_map p : lead_coef p^f = f (lead_coef p).
proof: Proof. have [-> | nz_p] := eqVneq p 0; first by rewrite !(rmorph0, lead_coef0). by rewrite lead_coef_map_eq // fmorph_eq0 // lead_coef_eq0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)