Quasi-Compact Perturbations of the Weyl Essential Spectrum and Application to Singular Transport Operators

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Leila Mebarki
Mohammed Benharrat
Bekkai Messirdi


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-A-K)^{-1}K or K(lambda-A-K)^{-1} is a quasi-compact operator. The obtained results are used to describe the Weyl essential spectrum of singular neutron transport operator.

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