proposition: Lemma is_cvg_ereal_nneg_natsum_cond m P : (forall n, (m <= n)%N -> P n -> 0 <= u_ n) -> cvgn (fun n => \sum_(m <= i < n | P i) u_ i).
proof: Proof. by move/lee_sum_nneg_natr/ereal_nondecreasing_cvgn => cu; apply: cvgP; exact: cu. Qed.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum matrix) mathcomp(interval rat) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(set_interval) reals ereal signed topology normedtype landau