proposition: Lemma fgposN D : fgpos (- D) = fgneg D.
proof: Proof. apply/eqP/freeg_eqP=> z. by rewrite !fgmap_f0_coeffE ?normr0 //= !coeffN oppr_ge0 normrN. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order generic_quotient) mathcomp(ssralg ssrnum ssrint)