proposition: Lemma coeff_Freeg x s : coeff x [freeg s] = precoeff x s.
proof: Proof. by rewrite /coeff fglift_Freeg precoeffE. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order generic_quotient) mathcomp(ssralg ssrnum ssrint)