A Characterization of Some Subsets of Essential Spectra of a Multivalued Linear Operator

摘要

In the present paper, we characterize some essential spectra of a closed linear relation in terms of certain linear relations type -and -Atkinson. This study leads us to generalize some well-known results for operators and to extend some results of small perturbations given by Alvarez and Wilcox in 6. In the same way, we present the perturbation classes of - and - Atkinson linear relations (see Theorem 3.3).