English

Center-preserving irreducible representations of finite groups

Group Theory 2026-03-12 v2 Representation Theory

Abstract

Given finite groups HGH \leq G, a representation σ\sigma of GG is called center-preserving on HH if the only elements of HH that become central under σ\sigma are those that were already central in GG. We prove that if HH has a faithful irreducible representation ρ\rho, then at least one of the irreducible components of the induction IndHG(ρ)\operatorname{Ind}_H^G(\rho) is center-preserving on HH. In consequence, HH has a faithful irreducible representation if and only if every finite group GG containing HH as a subgroup has an irreducible representation whose restriction to HH is faithful, and which is center-preserving on HH. In addition, we give examples illustrating the sharpness of the statement, and discuss the connection with projective representations.

Keywords

Cite

@article{arxiv.2601.15266,
  title  = {Center-preserving irreducible representations of finite groups},
  author = {Pierre-Emmanuel Caprace and Geoffrey Janssens and François Thilmany},
  journal= {arXiv preprint arXiv:2601.15266},
  year   = {2026}
}

Comments

19 pages. This second version includes minor corrections and improvements. Comments are welcome