proposition: Lemma commr_polyXn p n : GRing.comm p 'X^n.
proof: Proof. exact/commrX/commr_polyX. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)