Messirdi, Bekkai; Mebarki, Leila; Benharrat, Mohammed
(International Journal of Analysis and Applications, 2015-11-27)
This paper is devoted to the investigation of the stability of the Weyl essential spectrum of closed densely dened linear operator A subjected to additive perturbation K such that (lambda-AK)^{-1} K or K (lambda-AK)^{-1} ...