ArticleOriginal scientific text
Title
On a method of determining supports of Thoma's characters of discrete groups
Authors 1
Affiliations
- Institute of Mathematics Silesian, Technical University, Kaszubska 23, 44-100 Gliwice, Poland
Abstract
We present a new approach to determining supports of extreme, normed by 1, positive definite class functions of discrete groups, i.e. characters in the sense of E. Thoma [8]. Any character of a group produces a unitary representation and thus a von Neumann algebra of linear operators with finite normal trace. We use a theorem of H. Umegaki [9] on the uniqueness of conditional expectation in finite von Neumann algebras. Some applications and examples are given.
Keywords
positive definite functions, characters, traces
Bibliography
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Pages:
199-202
Main language of publication
English
Received
1996-09-20
Accepted
1996-11-05
Published
1997
Exact and natural sciences