proposition: Lemma lee_dsum_nneg_natl (f : nat -> \bar^d R) (P : pred nat) n : (forall m, (m < n)%N -> P m -> 0 <= f m) -> {homo (fun m => \sum_(m <= i < n | P i) (f i)) : i j / (i <= j)%N >-> j <= i}.
proof: Proof. move=> f0 i j le_ij; rewrite !dual_sumeE leeN2. apply: lee_sum_npos_natl => [m ? ?|//]; rewrite oppe_le0; exact: f0. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed