You are not currently logged in.
Access JSTOR through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The Spectral Diameter in Banach Algebras
Proceedings of the American Mathematical Society
Vol. 91, No. 1 (May, 1984), pp. 59-63
Published by: American Mathematical Society
Stable URL: http://www.jstor.org/stable/2045269
Page Count: 5
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
The element a is in the center of the Banach algebra A modulo its radical if and only if there is an upper bound for the diameters of the spectra of a - uau-1 for u invertible. Applications of this result are given to general Banach algebras and to the essential spectrum of operators on a Hilbert Space.
Proceedings of the American Mathematical Society © 1984 American Mathematical Society