proposition: Lemma polyOverXsubC c : ('X - c%:P \in polyOver S) = (c \in S).
proof: Proof. by rewrite rpredBl ?polyOverX ?polyOverC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)