Definition PS_minus (a b : nat -> V) (n : nat) : V := plus (a n) (opp (b n)).

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))).