{"title":"Compressed Cayley graph of groups","authors":"","doi":"10.1007/s13226-024-00567-7","DOIUrl":null,"url":null,"abstract":"<h3>Abstract</h3> <p>Let <em>G</em> be a group and let <em>S</em> be a subset of <span> <span>\\(G \\setminus \\{e\\}\\)</span> </span> with <span> <span>\\(S^{-1} \\subseteq S\\)</span> </span>, where <em>e</em> is the identity element of <em>G</em>. The Cayley graph <span> <span>\\(\\mathrm {{{\\,\\textrm{Cay}\\,}}}(G,S)\\)</span> </span> is a graph whose vertices are the elements of <em>G</em> and two distinct vertices <span> <span>\\(g,h\\in G\\)</span> </span> are adjacent if and only if <span> <span>\\(g^{-1} h\\in S\\)</span> </span>. Let <span> <span>\\(S \\subseteq Z(G)\\)</span> </span>. Then the relation <span> <span>\\( \\sim \\)</span> </span> on <em>G</em>, given by <span> <span>\\(a\\sim b\\)</span> </span> if and only if <span> <span>\\(Sa=Sb\\)</span> </span>, is an equivalence relation. Let <span> <span>\\(G_E\\)</span> </span> be the set of equivalence classes of <span> <span>\\(\\sim \\)</span> </span> on <em>G</em> and let [<em>a</em>] be the equivalence class of the element <em>a</em> in <em>G</em>. Then <span> <span>\\(G_E\\)</span> </span> is a group with operation <span> <span>\\([a].[b]=[ab]\\)</span> </span>. Also, let <span> <span>\\(S_E\\)</span> </span> be the set of equivalence classes of the elements of <em>S</em>. The compressed Cayley graph of <em>G</em> is introduced as the Cayley graph <span> <span>\\({{\\,\\textrm{Cay}\\,}}(G_E,S_E)\\)</span> </span>, which is denoted by <span> <span>\\({{\\,\\textrm{Cay}\\,}}_E(G,S)\\)</span> </span>. In this paper, we investigate some relations between <span> <span>\\(\\mathrm {{{\\,\\textrm{Cay}\\,}}}(G,S)\\)</span> </span> and <span> <span>\\({{\\,\\textrm{Cay}\\,}}_E(G,S)\\)</span> </span>. Also, we prove that <span> <span>\\(\\mathrm {{{\\,\\textrm{Cay}\\,}}}(G,S)\\)</span> </span> is a <span> <span>\\({{\\,\\textrm{Cay}\\,}}_E(G,S)\\)</span> </span>-generalized join of certain empty graphs. Moreover, we describe the structure of the compressed Cayley graph of <span> <span>\\(\\mathbb {Z}_n\\)</span> </span> by introducing a subset <em>S</em> such that <span> <span>\\({{\\,\\textrm{Cay}\\,}}_E(\\mathbb {Z}_n,S)\\)</span> </span> and <span> <span>\\({{\\,\\textrm{Cay}\\,}}(\\mathbb {Z}_n,S)\\)</span> </span> are not isomorphic, and we describe the Laplacian spectrum of <span> <span>\\({{\\,\\textrm{Cay}\\,}}(\\mathbb {Z}_n,S)\\)</span> </span>.</p>","PeriodicalId":501427,"journal":{"name":"Indian Journal of Pure and Applied Mathematics","volume":"1 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Indian Journal of Pure and Applied Mathematics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1007/s13226-024-00567-7","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Let G be a group and let S be a subset of \(G \setminus \{e\}\) with \(S^{-1} \subseteq S\), where e is the identity element of G. The Cayley graph \(\mathrm {{{\,\textrm{Cay}\,}}}(G,S)\) is a graph whose vertices are the elements of G and two distinct vertices \(g,h\in G\) are adjacent if and only if \(g^{-1} h\in S\). Let \(S \subseteq Z(G)\). Then the relation \( \sim \) on G, given by \(a\sim b\) if and only if \(Sa=Sb\), is an equivalence relation. Let \(G_E\) be the set of equivalence classes of \(\sim \) on G and let [a] be the equivalence class of the element a in G. Then \(G_E\) is a group with operation \([a].[b]=[ab]\). Also, let \(S_E\) be the set of equivalence classes of the elements of S. The compressed Cayley graph of G is introduced as the Cayley graph \({{\,\textrm{Cay}\,}}(G_E,S_E)\), which is denoted by \({{\,\textrm{Cay}\,}}_E(G,S)\). In this paper, we investigate some relations between \(\mathrm {{{\,\textrm{Cay}\,}}}(G,S)\) and \({{\,\textrm{Cay}\,}}_E(G,S)\). Also, we prove that \(\mathrm {{{\,\textrm{Cay}\,}}}(G,S)\) is a \({{\,\textrm{Cay}\,}}_E(G,S)\)-generalized join of certain empty graphs. Moreover, we describe the structure of the compressed Cayley graph of \(\mathbb {Z}_n\) by introducing a subset S such that \({{\,\textrm{Cay}\,}}_E(\mathbb {Z}_n,S)\) and \({{\,\textrm{Cay}\,}}(\mathbb {Z}_n,S)\) are not isomorphic, and we describe the Laplacian spectrum of \({{\,\textrm{Cay}\,}}(\mathbb {Z}_n,S)\).
Abstract Let G be a group and let S be a subset of \(G \setminus \{e\}\) with \(S^{-1} \subseteq S\) , where e is the identity element of G.Cayley graph ({{\textrm{Cay}\,}}(G,S)\)是一个图,它的顶点是 G 的元素,两个不同的顶点 \(g,h\in G\) 是相邻的,当且仅当\(g^{-1} h\in S\) 是相邻的。让(S子集Z(G)).那么 G 上的关系 \( \sim \), 由 \(a\sim b\) given if and only if \(Sa=Sb\) , 是一个等价关系。让 \(G_E\) 是 \(\sim \) 在 G 上的等价类的集合,让 [a] 是元素 a 在 G 中的等价类,那么 \(G_E\) 是一个具有操作 \([a].[b]=[ab]\) 的群。另外,让 \(S_E\) 是 S 中元素的等价类的集合。G 的压缩 Cayley 图被引入为 Cayley 图 \({{\,\textrm{Cay}\,}}(G_E,S_E)\)表示为 \({{\,textrm{Cay}\,}}_E(G,S)\) 。在本文中,我们研究了({{\textrm{Cay}\,}}(G,S))和({{\textrm{Cay}\,}}_E(G,S))之间的一些关系。同时,我们证明({{\textrm{Cay}\,}}(G,S))是一个-的广义连接。此外,我们通过引入子集 S 来描述 \({{\,\textrm{Cay}\,}}_E(\mathbb {Z}_n. S)\ 的压缩 Cayley 图的结构、)和({{\textrm{Cay}\,}}(\mathbb {Z}_n,S)\) 不是同构的,我们描述一下\({{\textrm{Cay}\,}}(\mathbb {Z}_n,S)\) 的拉普拉斯谱。