Isomorphisms of bi-Cayley graphs on generalized quaternion groups

Fuente: arXiv
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Auteurs principaux: Xie, Jin-Hua, Zhang, Zhishuo
Format: Preprint
Publié: 2024
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author Xie, Jin-Hua
Zhang, Zhishuo
author_facet Xie, Jin-Hua
Zhang, Zhishuo
contents Let $G$ be a finite group and $S$ be a subset of $G$. The bi-Cayley graph $\mathrm{BCay}(G,S)$ is the graph with vertex set $G\times \{0,1\}$ and edge set $\{\{(x,0),(sx,1)\}\mid x\in G,s\in S\}$. A bi-Cayley graph $\mathrm{BCay}(G,S)$ is called a BCI-graph if for every $T\subseteq G$, the isomorphism $\mathrm{BCay}(G,S)\cong \mathrm{BCay}(G,T)$ implies that $T=gS^α$ for some $g\in G$ and $α\in \mathrm{Aut}(G)$. We say a group $G$ an $m$-BCI-group if every bi-Cayley graphs of $G$ with valency at most $m$ is a BCI-graph. In this paper, we show that for $m\in\{2,3\}$, the generalized quaternion group of order $4n$ with $n\geq 2$ is an $m$-BCI-group if and only if it is an $m$-DCI-group if and only if it is an $m$-CI-group if and only if $n$ is odd or $n=2$.
format Preprint
id arxiv_https___arxiv_org_abs_2409_11918
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Isomorphisms of bi-Cayley graphs on generalized quaternion groups
Xie, Jin-Hua
Zhang, Zhishuo
Combinatorics
05C25, 20B25
Let $G$ be a finite group and $S$ be a subset of $G$. The bi-Cayley graph $\mathrm{BCay}(G,S)$ is the graph with vertex set $G\times \{0,1\}$ and edge set $\{\{(x,0),(sx,1)\}\mid x\in G,s\in S\}$. A bi-Cayley graph $\mathrm{BCay}(G,S)$ is called a BCI-graph if for every $T\subseteq G$, the isomorphism $\mathrm{BCay}(G,S)\cong \mathrm{BCay}(G,T)$ implies that $T=gS^α$ for some $g\in G$ and $α\in \mathrm{Aut}(G)$. We say a group $G$ an $m$-BCI-group if every bi-Cayley graphs of $G$ with valency at most $m$ is a BCI-graph. In this paper, we show that for $m\in\{2,3\}$, the generalized quaternion group of order $4n$ with $n\geq 2$ is an $m$-BCI-group if and only if it is an $m$-DCI-group if and only if it is an $m$-CI-group if and only if $n$ is odd or $n=2$.
title Isomorphisms of bi-Cayley graphs on generalized quaternion groups
topic Combinatorics
05C25, 20B25
url https://arxiv.org/abs/2409.11918