{"title":"将 2 星和 3 星打包到 (2,3) 不规则图中","authors":"Wenying Xi , Wensong Lin , Yuquan Lin","doi":"10.1016/j.dam.2024.10.022","DOIUrl":null,"url":null,"abstract":"<div><div>Let <span><math><mi>i</mi></math></span> be a positive integer, an <span><math><mi>i</mi></math></span>-star denoted by <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> is a complete bipartite graph <span><math><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mi>i</mi></mrow></msub></math></span>. An <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing of a graph <span><math><mi>G</mi></math></span> is a collection of vertex-disjoint subgraphs of <span><math><mi>G</mi></math></span> in which each subgraph is a 2-star or a 3-star. The maximum <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing problem is to find an <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing of a given graph containing the maximum number of vertices. The <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor problem is to answer whether there is an <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing containing all vertices of the given graph. The <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor problem is NP-complete in cubic graphs. In this paper we design a quadratic-time algorithm for finding an <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing of <span><math><mi>G</mi></math></span> that covers at least thirteen-sixteenths of its vertices with only a few exceptions. We also present some <span><math><mrow><mo>(</mo><mn>2</mn><mo>,</mo><mn>3</mn><mo>)</mo></mrow></math></span>-regular graphs with their maximum <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packings covering exactly thirteen-sixteenths of their vertices.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"361 ","pages":"Pages 440-452"},"PeriodicalIF":1.0000,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Packing 2- and 3-stars into (2,3)-regular graphs\",\"authors\":\"Wenying Xi , Wensong Lin , Yuquan Lin\",\"doi\":\"10.1016/j.dam.2024.10.022\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Let <span><math><mi>i</mi></math></span> be a positive integer, an <span><math><mi>i</mi></math></span>-star denoted by <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> is a complete bipartite graph <span><math><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mi>i</mi></mrow></msub></math></span>. An <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing of a graph <span><math><mi>G</mi></math></span> is a collection of vertex-disjoint subgraphs of <span><math><mi>G</mi></math></span> in which each subgraph is a 2-star or a 3-star. The maximum <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing problem is to find an <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing of a given graph containing the maximum number of vertices. The <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor problem is to answer whether there is an <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing containing all vertices of the given graph. The <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor problem is NP-complete in cubic graphs. In this paper we design a quadratic-time algorithm for finding an <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packing of <span><math><mi>G</mi></math></span> that covers at least thirteen-sixteenths of its vertices with only a few exceptions. We also present some <span><math><mrow><mo>(</mo><mn>2</mn><mo>,</mo><mn>3</mn><mo>)</mo></mrow></math></span>-regular graphs with their maximum <span><math><mrow><mo>{</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>}</mo></mrow></math></span>-packings covering exactly thirteen-sixteenths of their vertices.</div></div>\",\"PeriodicalId\":50573,\"journal\":{\"name\":\"Discrete Applied Mathematics\",\"volume\":\"361 \",\"pages\":\"Pages 440-452\"},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2024-11-14\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Discrete Applied Mathematics\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0166218X24004530\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS, APPLIED\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Applied Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0166218X24004530","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS, APPLIED","Score":null,"Total":0}
引用次数: 0
摘要
让 i 为正整数,用 Si 表示的 i-star 是一个完整的双方形图 K1,i。图 G 的 {S2,S3} 组合是 G 的顶点相交子图的集合,其中每个子图都是 2-star 或 3-star。最大{S2,S3}堆积问题是指找到一个包含最多顶点数的给定图的{S2,S3}堆积。{S2,S3}因子问题是回答是否存在包含给定图形所有顶点的{S2,S3}堆积。在立方图中,{S2,S3} 因子问题是 NP-完全的。在本文中,我们设计了一种二次方时间算法,用于找到 G 的 {S2,S3} 组合,该组合至少覆盖了其十六分之三的顶点,只有少数例外。我们还介绍了一些 (2,3) 不规则图,它们的最大 {S2,S3} 组合正好覆盖了其十六分之十三的顶点。
Let be a positive integer, an -star denoted by is a complete bipartite graph . An -packing of a graph is a collection of vertex-disjoint subgraphs of in which each subgraph is a 2-star or a 3-star. The maximum -packing problem is to find an -packing of a given graph containing the maximum number of vertices. The -factor problem is to answer whether there is an -packing containing all vertices of the given graph. The -factor problem is NP-complete in cubic graphs. In this paper we design a quadratic-time algorithm for finding an -packing of that covers at least thirteen-sixteenths of its vertices with only a few exceptions. We also present some -regular graphs with their maximum -packings covering exactly thirteen-sixteenths of their vertices.
期刊介绍:
The aim of Discrete Applied Mathematics is to bring together research papers in different areas of algorithmic and applicable discrete mathematics as well as applications of combinatorial mathematics to informatics and various areas of science and technology. Contributions presented to the journal can be research papers, short notes, surveys, and possibly research problems. The "Communications" section will be devoted to the fastest possible publication of recent research results that are checked and recommended for publication by a member of the Editorial Board. The journal will also publish a limited number of book announcements as well as proceedings of conferences. These proceedings will be fully refereed and adhere to the normal standards of the journal.
Potential authors are advised to view the journal and the open calls-for-papers of special issues before submitting their manuscripts. Only high-quality, original work that is within the scope of the journal or the targeted special issue will be considered.