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