Finite groups, commuting probability, and coprime automorphisms

Fuente: arXiv
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Autori principali: Detomi, Eloisa, Guralnick, Robert M., Morigi, Marta, Shumyatsky, Pavel
Natura: Preprint
Pubblicazione: 2025
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author Detomi, Eloisa
Guralnick, Robert M.
Morigi, Marta
Shumyatsky, Pavel
author_facet Detomi, Eloisa
Guralnick, Robert M.
Morigi, Marta
Shumyatsky, Pavel
contents Given two subgroups $H,K$ of a finite group $G$, the probability that a pair of random elements from $H$ and $K$ commutes is denoted by $Pr(H,K)$. Suppose that a finite group $G$ admits a group of coprime automorphisms $A$ and let $ε>0$. We show that, if for any distinct primes $p,q\inπ(G)$ there is an $A$-invariant Sylow $p$-subgroup $P$ and an $A$-invariant Sylow $q$-subgroup $Q$ of $G$ for which $Pr([P,A],[Q,A])\geε$, then $F_2([G,A])$ has $ε$-bounded index in $[G,A]$ (Theorem 1.2). Here $F_2(K)$ stands for the second term of the upper Fitting seris of a group $K$. We also show that, if $G=[G,A]$ and for any prime $p$ dividing the order of $G$ there is an $A$-invariant Sylow $p$-subgroup $P$ such that $\Pr([P,A], [P,A]^x)\geqε$ for all $x\in G$, then $G$ is bounded-by-abelian-by-bounded (Theorem 1.4).
format Preprint
id arxiv_https___arxiv_org_abs_2511_07597
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Finite groups, commuting probability, and coprime automorphisms
Detomi, Eloisa
Guralnick, Robert M.
Morigi, Marta
Shumyatsky, Pavel
Group Theory
20D20, 20D45, 20P05
Given two subgroups $H,K$ of a finite group $G$, the probability that a pair of random elements from $H$ and $K$ commutes is denoted by $Pr(H,K)$. Suppose that a finite group $G$ admits a group of coprime automorphisms $A$ and let $ε>0$. We show that, if for any distinct primes $p,q\inπ(G)$ there is an $A$-invariant Sylow $p$-subgroup $P$ and an $A$-invariant Sylow $q$-subgroup $Q$ of $G$ for which $Pr([P,A],[Q,A])\geε$, then $F_2([G,A])$ has $ε$-bounded index in $[G,A]$ (Theorem 1.2). Here $F_2(K)$ stands for the second term of the upper Fitting seris of a group $K$. We also show that, if $G=[G,A]$ and for any prime $p$ dividing the order of $G$ there is an $A$-invariant Sylow $p$-subgroup $P$ such that $\Pr([P,A], [P,A]^x)\geqε$ for all $x\in G$, then $G$ is bounded-by-abelian-by-bounded (Theorem 1.4).
title Finite groups, commuting probability, and coprime automorphisms
topic Group Theory
20D20, 20D45, 20P05
url https://arxiv.org/abs/2511.07597