proposition: Lemma size_Cmul a p : a != 0 -> size (a%:P * p) = size p.
proof: Proof. by rewrite mul_polyC => /size_scale->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)