English

A generalized character related to the local structure and representation theory of a finite group

Representation Theory 2025-10-22 v4 Group Theory

Abstract

We consider the generalized character Ψ1,p,G\Psi_{1,p,G} of a finite group GG which vanishes on all pp-singular elements of GG and whose value at each pp-regular yGy \in G is the number of pp-elements of CG(y)C_{G}(y). We conjecture that this is always a character, and may be afforded by a projective RGRG-module, where RR is an appropriate complete discrete valuation ring whose residue field has characteristic pp. We examine a number of case where this is the case, and consider consequences for the representation theory and character theory of GG when this conjecture is known to hold. In particular, we prove, among other things, that the conjecture is valid for all primes pp in the case that GPSL(2,q)G \cong {\rm PSL}(2,q) or SL(2,q){\rm SL}(2,q) for every prime power qq.

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Cite

@article{arxiv.2505.03976,
  title  = {A generalized character related to the local structure and representation theory of a finite group},
  author = {Geoffrey R. Robinson},
  journal= {arXiv preprint arXiv:2505.03976},
  year   = {2025}
}

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37 pages