proposition: Lemma fgscaleA c1 c2 D : c1 *:F (c2 *:F D) = (c1 * c2) *:F D.
proof: Proof. by apply/eqP/freeg_eqP=> x; rewrite !coeff_fgscale mulrA. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order generic_quotient) mathcomp(ssralg ssrnum ssrint)