On the discrete spectrum of linear operators in Hilbert spaces [Elektronische Ressource] / Marcel Hansmann

On the discrete spectrum of linearoperators in Hilbert spacesD i s s e r t a t i o nzur Erlangung des Doktorgradesder Naturwissenschaftenvorgelegt vonDipl.-Math. Marcel Hansmannaus Stadtoldendorfgenehmigt von der Fakult at furMathematik/Informatik und Maschinenbauder Technischen Universit at ClausthalTag der mundlic hen Prufung10.02.2010Vorsitzender der Promotionskommission:Prof. Dr. Jurgen Dix, TU ClausthalHauptberichterstatter:Prof. Dr. Michael Demuth, TU ClausthalBerichterstatter:Prof. Dr. Werner Kirsch, FernUniversit at in HagenPD Dr. habil. Johannes Brasche, TU ClausthalAcknowledgmentsI would like to thank my supervisor Prof. Dr. Michael Demuth for his guidance duringmy years in Clausthal, for many valuable mathematical and non-mathematical discus-sions, and for his constant support. Furthermore, my thanks go to Dr. Guy Katrielfor an enjoyable collaboration, a fruitful co-authorship, and his helpful comments onearlier versions of this thesis. I am grateful to Dr. habil. Michael J. Gruber who readthe nal version of this manuscript and whose suggestions helped to improve the math-ematical as well as the grammatical quality of this work. Finally, I would like to thankProf. Dr. Werner Kirsch and Dr. habil. Johannes Brasche for their willingness to reviewthis thesis.