proposition: Lemma map_polyXn n : ('X^n)^f = 'X^n.
proof: Proof. by rewrite rmorphXn /= map_polyX. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)