Session 14. Group Rings and Related Topics

Some invariants of the character ring of a finite group

Tim Fritzsche, FSU Jena, Germany
Let \(G\) be a finite group and \(R(G)\) be its character ring, i.e. the set of \(\mathbb{Z}\) - linear combinations of complex characters of \(G.\) Then \(R(G)\) is a \(\mathbb{Z}\)-order in \(\mathbb{Q} \otimes R(G).\) A natural strategy to study algebraic properties of the character ring is to consider the maximal order in \(\mathbb{Q} \otimes R(G).\) Doing this we will see that it is not diļ¬ƒcult to determine the unit group and the Brauer group of \(R(G).\)

However, in general it seems to be hard to decide whether the representation type of \(R(G)\) is finite. We will give some necessary and sufficient conditions for the finiteness of the representation type of \(R(G).\) These yield the answer to this problem in a number of cases.

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