On the subgroup regular set in Cayley graphs

Fuente: arXiv
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Auteurs principaux: Khaefi, Asamin, Akhlaghi, Zeinab, Khosravi, Behrooz
Format: Preprint
Publié: 2023
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author Khaefi, Asamin
Akhlaghi, Zeinab
Khosravi, Behrooz
author_facet Khaefi, Asamin
Akhlaghi, Zeinab
Khosravi, Behrooz
contents A subset $C$ of the vertex set of a graph $Γ$ is said to be $(a,b)$-regular if $C$ induces an $a$-regular subgraph and every vertex outside $C$ is adjacent to exactly $b$ vertices in $C$. In particular, if $C$ is an $(a,b)$-regular set of some Cayley graph on a finite group $G$, then $C$ is called an $(a,b)$-regular set of $G$ and a $(0,1)$-regular set is called a perfect code of $G$. In [Wang, Xia and Zhou, Regular sets in Cayley graphs, J. Algebr. Comb., 2022] it is proved that if $H$ is a normal subgroup of $G$, then $H$ is a perfect code of $G$ if and only if it is an $(a,b)$-regular set of $G$, for each $0\leq a\leq|H|-1$ and $0\leq b\leq|H|$ with $\gcd(2,|H|-1)\mid a$. In this paper, we generalize this result and show that a subgroup $H$ of $G$ is a perfect code of $G$ if and only if it is an $(a,b)$-regular set of $G$, for each $0\leq a\leq|H|-1$ and $0\leq b\leq|H|$ such that $\gcd(2,|H|-1)$ divides $a$.
format Preprint
id arxiv_https___arxiv_org_abs_2308_11434
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On the subgroup regular set in Cayley graphs
Khaefi, Asamin
Akhlaghi, Zeinab
Khosravi, Behrooz
Combinatorics
A subset $C$ of the vertex set of a graph $Γ$ is said to be $(a,b)$-regular if $C$ induces an $a$-regular subgraph and every vertex outside $C$ is adjacent to exactly $b$ vertices in $C$. In particular, if $C$ is an $(a,b)$-regular set of some Cayley graph on a finite group $G$, then $C$ is called an $(a,b)$-regular set of $G$ and a $(0,1)$-regular set is called a perfect code of $G$. In [Wang, Xia and Zhou, Regular sets in Cayley graphs, J. Algebr. Comb., 2022] it is proved that if $H$ is a normal subgroup of $G$, then $H$ is a perfect code of $G$ if and only if it is an $(a,b)$-regular set of $G$, for each $0\leq a\leq|H|-1$ and $0\leq b\leq|H|$ with $\gcd(2,|H|-1)\mid a$. In this paper, we generalize this result and show that a subgroup $H$ of $G$ is a perfect code of $G$ if and only if it is an $(a,b)$-regular set of $G$, for each $0\leq a\leq|H|-1$ and $0\leq b\leq|H|$ such that $\gcd(2,|H|-1)$ divides $a$.
title On the subgroup regular set in Cayley graphs
topic Combinatorics
url https://arxiv.org/abs/2308.11434