THE STABILITY RADIUS OF A QUASI-FREDHOLM OPERATOR

Authors
POON PW
Citation
Pw. Poon, THE STABILITY RADIUS OF A QUASI-FREDHOLM OPERATOR, Proceedings of the American Mathematical Society, 126(4), 1998, pp. 1071-1080
Citations number
14
Categorie Soggetti
Mathematics,Mathematics,Mathematics,Mathematics
Journal title
Proceedings of the American Mathematical Society → ACNP
ISSN journal
00029939
Volume
126
Issue
4
Year of publication
1998
Pages
1071 - 1080
Database
ISI
SICI code
0002-9939(1998)126:4<1071:TSROAQ>2.0.ZU;2-O
Abstract
We extend the technique used by Kordula and Muller to show that the st ability radius of a quasi-Fredholm operator T is the limit of gamma(T- n)(1/n) as n --> infinity. If 0 is an isolated point of the Apostol sp ectrum sigma(gamma)(T), then the above limit is non-zero if and only i f T is quasi-Fredholm.