Resumen de Browder and semi-Browder operators and perturbation function

Fatma Fakhfakh, Maher Mnif

• This paper is devoted to the investigation of the stability of closed densely de¯ned semi-Browder and Browder operators on Banach spaces. Our approach consists to introduce the concepts of a perturbation function and a coperturbation function in order to deduce the stability under strictly singular and cosingular operator perturbations. Further, our results are used to show the invariance of Browder's spectrum