Journal of Inequalities and Applications
Volume 2009 (2009), Article ID 284526, 13 pages
Research Article

Perturbation Results on Semi-Fredholm Operators and Applications

Département de Maths, Faculté des Sciences de Sfax, B. P. 1171, 3000 Sfax, Tunisia

Received 14 July 2009; Accepted 26 September 2009

Academic Editor: Jozef Banas

Copyright © 2009 Boulbeba Abdelmoumen and Hamadi Baklouti. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We give some results concerning stability in the Fredholm operators and Browder operators set, via the concept of measure of noncompactness. Moreover, we prove some localization results on the essential spectra of bounded operators on Banach space. As application, we describe the essential spectra of weighted shift operators. Finally, we describe the spectra of polynomially compact operators, and we use the obtained results to study the solvability for operator equations in Banach spaces.