Perturbation theory for selfadjoint relations
We study Weyl-type perturbation theorems in the context of closed linear relations. General results on perturbations for dissipative relations are established. In the particular case of selfadjoint relations, we treat finite-rank perturbations and carry out a detailed analysis of the corresponding changes in the spectrum.
KeywordsClosed linear relations Dissipative and Selfadjoint relations Weyl perturbation theory
Mathematics Subject Classification47A06 47B25 47A55
This research was supported by UNAM-DGAPA-PAPIIT IN110818 and SEP-CONACYT CB-2015 254062. Part of this work was carried out while LOS was on sabbatical leave from UNAM with the support of PASPA-DGAPA-UNAM. The authors express their deep gratitude to the referee for comments and suggestions which have led to an improved presentation of this work.