On reducible Killing forms for groups of Lie type

Fuente: arXiv
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Main Authors: Piterman, Kevin Ivan, Roelants, Charlotte
Format: Preprint
Published: 2025
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author Piterman, Kevin Ivan
Roelants, Charlotte
author_facet Piterman, Kevin Ivan
Roelants, Charlotte
contents Killing forms on finite groups arise as examples of braided Killing forms on braided Lie algebras. For a finite group $G$ and a $G$-stable subset $\mathcal{C}$, the Killing form associated with $\mathbb{C}[\mathcal{C}]$ is given by $K_{\mathcal{C}}(a,b) = |C_G(ab) \cap \mathcal{C}|$ for $a,b\in \mathcal{C}$. Motivated by Cartan's criterion for semisimplicity of Lie algebras, and previous work of López Peña, Majid, and Rietsch, we study the non-degeneracy and irreducibility of $K_{\mathcal{C}}$ when $\mathcal{C}$ is a conjugacy class of involutions or unipotent elements in a finite simple group of Lie type and Lie rank one. Our approach suggests interesting connections with character theory, related counting formulas, and the study of commuting graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2507_17902
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On reducible Killing forms for groups of Lie type
Piterman, Kevin Ivan
Roelants, Charlotte
Group Theory
20C33, 20G40, 20D06, 05E18
Killing forms on finite groups arise as examples of braided Killing forms on braided Lie algebras. For a finite group $G$ and a $G$-stable subset $\mathcal{C}$, the Killing form associated with $\mathbb{C}[\mathcal{C}]$ is given by $K_{\mathcal{C}}(a,b) = |C_G(ab) \cap \mathcal{C}|$ for $a,b\in \mathcal{C}$. Motivated by Cartan's criterion for semisimplicity of Lie algebras, and previous work of López Peña, Majid, and Rietsch, we study the non-degeneracy and irreducibility of $K_{\mathcal{C}}$ when $\mathcal{C}$ is a conjugacy class of involutions or unipotent elements in a finite simple group of Lie type and Lie rank one. Our approach suggests interesting connections with character theory, related counting formulas, and the study of commuting graphs.
title On reducible Killing forms for groups of Lie type
topic Group Theory
20C33, 20G40, 20D06, 05E18
url https://arxiv.org/abs/2507.17902