proposition: Lemma fgnorm_decomp D : fgnorm D = fgpos D + fgneg D.
proof: Proof. apply/eqP/freeg_eqP=> k. rewrite coeffD coeff_fgnormE coeff_fgposE coeff_fgnegE. by case: ger0P; rewrite (sub0r, subr0). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order generic_quotient) mathcomp(ssralg ssrnum ssrint)