The Chebotarev invariant for direct products of nonabelian finite simple groups

Fuente: arXiv
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Autores principales: Anzanello, Jessica, Lucchini, Andrea, Tracey, Gareth
Formato: Preprint
Publicado: 2024
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author Anzanello, Jessica
Lucchini, Andrea
Tracey, Gareth
author_facet Anzanello, Jessica
Lucchini, Andrea
Tracey, Gareth
contents A subset $\{g_1, \ldots , g_d\}$ of a finite group $G$ invariably generates $G$ if $\{g_1^{x_1}, \ldots , g_d^{x_d}\}$ generates $G$ for every choice of $x_i \in G$. The Chebotarev invariant $C(G)$ of $G$ is the expected value of the random variable $n$ that is minimal subject to the requirement that $n$ randomly chosen elements of $G$ invariably generate $G$. In this paper, we show that if $G$ is a nonabelian finite simple group, then $C(G)$ is absolutely bounded. More generally, we show that if $G$ is a direct product of $k$ nonabelian finite simple groups, then $C(G)=\log{k}/\log{α(G)}+O(1)$, where $α$ is an invariant completely determined by the proportion of derangements of the primitive permutation actions of the factors in $G$. It follows from the proof of the Boston-Shalev conjecture that $C(G)=O(\log{k})$. We also derive sharp bounds on the expected number of generators for $G$.
format Preprint
id arxiv_https___arxiv_org_abs_2408_12298
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Chebotarev invariant for direct products of nonabelian finite simple groups
Anzanello, Jessica
Lucchini, Andrea
Tracey, Gareth
Group Theory
A subset $\{g_1, \ldots , g_d\}$ of a finite group $G$ invariably generates $G$ if $\{g_1^{x_1}, \ldots , g_d^{x_d}\}$ generates $G$ for every choice of $x_i \in G$. The Chebotarev invariant $C(G)$ of $G$ is the expected value of the random variable $n$ that is minimal subject to the requirement that $n$ randomly chosen elements of $G$ invariably generate $G$. In this paper, we show that if $G$ is a nonabelian finite simple group, then $C(G)$ is absolutely bounded. More generally, we show that if $G$ is a direct product of $k$ nonabelian finite simple groups, then $C(G)=\log{k}/\log{α(G)}+O(1)$, where $α$ is an invariant completely determined by the proportion of derangements of the primitive permutation actions of the factors in $G$. It follows from the proof of the Boston-Shalev conjecture that $C(G)=O(\log{k})$. We also derive sharp bounds on the expected number of generators for $G$.
title The Chebotarev invariant for direct products of nonabelian finite simple groups
topic Group Theory
url https://arxiv.org/abs/2408.12298