proposition: Lemma fin_num_sumeN I s (P : pred I) (f : I -> \bar R) : (forall i, P i -> f i \is a fin_num) -> \sum_(i <- s | P i) - f i = - \sum_(i <- s | P i) f i.
proof: Proof. by move=> h; rewrite sumeN// => i j Pi Pj; rewrite fin_num_adde_defl// h. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed