English

On some rational extension properties for $GL_n(q)$ and even-degree characters fixed by order-2 Galois automorphisms

Group Theory 2022-12-16 v2 Representation Theory

Abstract

In this note, we prove that if every character of a finite group GG fixed by an order-2 Galois automorphism has odd degree, then GG has a normal Sylow 22-subgroup. On the way, we study extensions of characters of GLn(q)GL_n(q), qq odd, to the group extended by the transpose-inverse automorphism and prove that unipotent characters of PSLn(q)PSL_n(q) extend to rational characters of its automorphism group.

Keywords

Cite

@article{arxiv.2212.04536,
  title  = {On some rational extension properties for $GL_n(q)$ and even-degree characters fixed by order-2 Galois automorphisms},
  author = {A. A. Schaeffer Fry},
  journal= {arXiv preprint arXiv:2212.04536},
  year   = {2022}
}

Comments

Thm. A, Cor. B, are incorrect as stated and would require additional assumptions on q (a result of a missing assumption in another paper). Withdrawn until I obtain a working solution