proposition: Lemma cv_cauchy_2 : forall An:nat -> R, Cauchy_crit_series An -> { l:R | Un_cv (fun N:nat => sum_f_R0 An N) l }.
proof: Proof. intros. apply R_complete. unfold Cauchy_crit_series in H. exact H. Qed.
imports: Rbase Rfunctions Rseries Rcomplete