August 23, 2021

Prof. Dr. Klaus W. Roggenkamp deceased

The Faculty of Mathematics and Physics at the University of Stuttgart and the Institute for Algebra and
Number Theory mourn the death of

Professor Dr. Klaus W. Roggenkamp
24.12.1940 - 23.7.2021


Mr. Roggenkamp studied mathematics in Giessen (Ph.D. 1967, Habilitation 1970) and did research at the at the University of Illinois in Urbana-Champaign, at the University of Montreal and the McGill University in Montreal. After a professorship in Bielefeld (1970-1974), he held the position of professor from April 1974 until his retirement in June 2002, he held the chair of Algebra in Stuttgart. He was a member of the Academy of Sciences in Erfurt and an honorary doctor of the University of Constanța.


Mr. Roggenkamp was a leader in the theory of classical orders and in integer representation theory. In addition to numerous articles, he also contributed three books - Lattices over Orders. Volume I (co-authored with Verena Huber-Dyson) and Volume II, and Integral representation Theory (together with Irving Reiner) - and organized, mostly together with Irving Reiner, conferences in Oberwolfach. 


Together with Karl Grünberg, Mr. Roggenkamp worked on homological questions about groups and group rings and together with Leonard Scott on the isomorphism problem for integer group rings. Roggenkamp and Scott succeeded completely surprisingly in solving the isomorphism problem for finite p-groups over the p-adic numbers by proving a stronger statement and thus proving a conjecture of Zassenhaus in this case, while they disproved this conjecture in other situations. Mr. Roggenkamp contributed in 1990 to the International Congress of Mathematicians in Kyoto about the joint work with Scott ("The isomorphism problem for integral group rings of finite groups"). The development initiated by this work led to a negative solution of the general isomorphism problem and to refutations of all refutations of all Zassenhaus conjectures in the general form. Also on integer group rings, Mr. Roggenkamp published several books, among others together with Martin Taylor. 


Mr. Roggenkamp gave inspiring lectures and supervised numerous theses and doctorates; Mathematics Genealogy now lists eighty mathematical descendants of Klaus Roggenkamp. The Faculty of Mathematics and Physics and the Institute for Algebra and Number Theory sincerely thank him for his many years of service and will honor his memory.

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