(** ** Abel's theorem for power series *)

(* Specifications: *)
Lemma Abel (a : nat -> R) :
Rbar_lt 0 (CV_radius a) -> Rbar_lt (CV_radius a) p_infty
-> ex_pseries a (CV_radius a)
-> filterlim (PSeries a) (at_left (CV_radius a)) (locally (PSeries a (CV_radius a))).