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