A local Banach algebra is a normed algebra which satisfies the following
properties:
1. If
and
is an analytic function on a neighborhood of
the spectrum of
in the completion of
, with
if
is non-unital, then
.
2. All matrix algebras over satisfy property (1) above.
Here, if
is a
-algebra,
then it will be called a local Banach
-algebra; similarly, if
is a pre-
-norm, then
is called a local C-*-algebra
(though different literature uses the term "local
-algebra" to refer to different structures altogether).
An algebra satisfying condition (1) above is said to be closed under holomorphic functional calculus.