Perturbation theory for selfadjoint relations

Abstract

We study Weyl-type perturbation theorems in the context of linear closed relations. General results on perturbations for dissipative relations are established. In the particular case of selfadjoint relations, we study finite-rank perturbations and carry out a detailed analysis of the corresponding changes in the spectrum. Mathematics Subject Classification(2010): 47A06; 47B25; 47A55