Characterization of $\PSL(2,q)$ by the number of singular elements

Fuente: arXiv
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Main Authors: Shen, Rulin, Yan, Deyu
Format: Preprint
Published: 2025
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author Shen, Rulin
Yan, Deyu
author_facet Shen, Rulin
Yan, Deyu
contents Given a finite group $G$, let $π(G)$ denote the set of all primes that divide the order of $G$. For a prime $r \in π(G)$, we define $r$-singular elements as those elements of $G$ whose order is divisible by $r$. Denote by $S_r(G)$ the number of $r$-singluar elements of $G$. We denote the proportion $S_r(G)/|G|$ of $r$-singular elements in $G$ by ${μ_r}(G)$. Let $μ(G) := {\{μ_r}(G) | r\in π(G)\}$ be the set of all proportions of $r$-singular elements for each prime $r$ in $π(G)$. In this paper, we prove that if a finite group $G$ has the same set $μ(G)$ as the simple group $\PSL(2,q)$, then $G$ is isomorphic to $\PSL(2,q)$.
format Preprint
id arxiv_https___arxiv_org_abs_2503_24212
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Characterization of $\PSL(2,q)$ by the number of singular elements
Shen, Rulin
Yan, Deyu
Group Theory
Given a finite group $G$, let $π(G)$ denote the set of all primes that divide the order of $G$. For a prime $r \in π(G)$, we define $r$-singular elements as those elements of $G$ whose order is divisible by $r$. Denote by $S_r(G)$ the number of $r$-singluar elements of $G$. We denote the proportion $S_r(G)/|G|$ of $r$-singular elements in $G$ by ${μ_r}(G)$. Let $μ(G) := {\{μ_r}(G) | r\in π(G)\}$ be the set of all proportions of $r$-singular elements for each prime $r$ in $π(G)$. In this paper, we prove that if a finite group $G$ has the same set $μ(G)$ as the simple group $\PSL(2,q)$, then $G$ is isomorphic to $\PSL(2,q)$.
title Characterization of $\PSL(2,q)$ by the number of singular elements
topic Group Theory
url https://arxiv.org/abs/2503.24212