Theorem
4.15. Suppose
. Then the set of points z for which the series converges
is one of the following:
(i) The single
point
.
(ii) The
disk
, along
with part (either none, or some or all) of the
circle
.
(iii) The entire complex
plane.
Proof.
Proof of Theorem 4.15 is in the book.