(TU Clausthal, Germany)
"Determining Spectra by Integral Conditions"
Abstract: Semigroup differences are a powerful tool for studying the spectra of selfadjoint operators. If they are assumed to be integral operators certain integral conditions determine the essential spectra, the absolutely continuous spectra or the momenta and distribution of eigenvalues.
We will give an overview on possible results, ideas of some proofs and examples of various perturbations.