Twisted Frobenius-Schur Indicators and Character Degree Sums in Dihedral Groups

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Main Authors: Yerrapati, Venkata Subbaiah, Dixit, Rahul, Shukla, Ajay Kumar
Format: Preprint
Published: 2026
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author Yerrapati, Venkata Subbaiah
Dixit, Rahul
Shukla, Ajay Kumar
author_facet Yerrapati, Venkata Subbaiah
Dixit, Rahul
Shukla, Ajay Kumar
contents Let $G$ be a finite group and $T(G)$ be the sum of the degrees of its irreducible complex representations. We investigate the relationship between $T(G)$ and the number of twisted involutions $m_σ= |\{g \in G \mid σ(g) = g^{-1}\}|$ for an automorphism $σ$. While it is known that $T(G) = m_e$ for the identity automorphism $e$ in certain cases (e.g., real characters), we analyze this relation for non-identity automorphisms of groups of order $p, 2p, p^2$. We prove that for the family of Dihedral groups $D_n$, the inequality $T(D_n) \geq m_σ$ holds for all $σ\in \mathrm{Aut}(D_n)$. We provide a complete classification of $m_σ$ using number-theoretic properties of the automorphism parameters.
format Preprint
id arxiv_https___arxiv_org_abs_2605_22127
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Twisted Frobenius-Schur Indicators and Character Degree Sums in Dihedral Groups
Yerrapati, Venkata Subbaiah
Dixit, Rahul
Shukla, Ajay Kumar
Group Theory
Representation Theory
Primary 20C15, 20F28, 20F55, Secondary 20B25, 20B35
Let $G$ be a finite group and $T(G)$ be the sum of the degrees of its irreducible complex representations. We investigate the relationship between $T(G)$ and the number of twisted involutions $m_σ= |\{g \in G \mid σ(g) = g^{-1}\}|$ for an automorphism $σ$. While it is known that $T(G) = m_e$ for the identity automorphism $e$ in certain cases (e.g., real characters), we analyze this relation for non-identity automorphisms of groups of order $p, 2p, p^2$. We prove that for the family of Dihedral groups $D_n$, the inequality $T(D_n) \geq m_σ$ holds for all $σ\in \mathrm{Aut}(D_n)$. We provide a complete classification of $m_σ$ using number-theoretic properties of the automorphism parameters.
title Twisted Frobenius-Schur Indicators and Character Degree Sums in Dihedral Groups
topic Group Theory
Representation Theory
Primary 20C15, 20F28, 20F55, Secondary 20B25, 20B35
url https://arxiv.org/abs/2605.22127