On left-right generalized Fredholm spectra and some perturbations results

Abstract

In this article, we study the invariance of left and right generalized Fredholm and generalized Weyl spectra of Yang type for bounded and unbounded linear operators acting on Banach spaces. The results are formulated in terms of some topological conditions on the spaces and the classes of generalized Fredholm perturbations sets. An application for block operators matrices is then developed. Our results extend and generalize many results in the classical Fredholm theory.