On the pseudo semi-Browder essential spectra and application to 2 × 2 block operator matrices


Faiçal Abdmouleh, Bilel Elgabeur




In the present paper, we introduce and study the pseudo semi-Browder essential spectra of bounded linear operators in a Banach space. We start by defining the pseudo semi-Browder operators and we prove the stability of these operators under commuting Riesz operator perturbations. Then, we apply the obtained results to study the stability of the pseudo semi-Browder essential spectra. We show as well the relation between the pseudo semi-Browder spectrum of the sum of two bounded linear operators and the pseudo semi-Browder spectrum of each of these operators. As an application, we study the pseudo semi-Browder spectra of 2 × 2 block operator matrices.