End PS_plus.

(* Specifications: *)
Lemma PSeries_plus (a b : nat -> R) (x : R) :
ex_pseries a x -> ex_pseries b x
-> PSeries (PS_plus a b) x = PSeries a x + PSeries b x.
Lemma CV_disk_plus (a b : nat -> R) (x : R) :
(CV_disk a x) -> (CV_disk b x)
-> (CV_disk (PS_plus a b) x).
Lemma CV_radius_plus (a b : nat -> R) :
Rbar_le (Rbar_min (CV_radius a) (CV_radius b)) (CV_radius (PS_plus a b)).