Gustafson, weidman, kato, wolf, schechter, browder, Rakočević and Schmoeger essential spectra of the sum of two bounded operators and application to a transport operator

Abstract

Abstract In this paper we investigate the essential spectra of the sum of two bounded linear operators defined on a Banach space by means of the essential spectra of each of the two operators where their products are Fredholm or semi‐Fredholm perturbations. Furthermore, we give an application to a transport operator. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim