{"title":"避开顶点的连线和可移动路径","authors":"Xiying Du, Yanjia Li, Shijie Xie , Xingxing Yu","doi":"10.1016/j.jctb.2024.06.006","DOIUrl":null,"url":null,"abstract":"<div><p>A graph <em>G</em> is <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mi>m</mi><mo>)</mo></math></span>-linked if, for any distinct vertices <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> in <em>G</em>, there exist disjoint connected subgraphs <span><math><mi>A</mi><mo>,</mo><mi>B</mi></math></span> of <em>G</em> such that <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>∈</mo><mi>V</mi><mo>(</mo><mi>A</mi><mo>)</mo></math></span> and <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>∈</mo><mi>V</mi><mo>(</mo><mi>B</mi><mo>)</mo></math></span>. A fundamental result in structural graph theory is the characterization of <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mn>2</mn><mo>)</mo></math></span>-linked graphs. It appears to be difficult to characterize <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mi>m</mi><mo>)</mo></math></span>-linked graphs for <span><math><mi>m</mi><mo>≥</mo><mn>3</mn></math></span>. In this paper, we provide a partial characterization of <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mi>m</mi><mo>)</mo></math></span>-linked graphs. This implies that every <span><math><mo>(</mo><mn>2</mn><mi>m</mi><mo>+</mo><mn>2</mn><mo>)</mo></math></span>-connected graphs <em>G</em> is <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mi>m</mi><mo>)</mo></math></span>-linked and for any distinct vertices <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> of <em>G</em>, there is a path <em>P</em> in <em>G</em> between <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> and avoiding <span><math><mo>{</mo><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>}</mo></math></span> such that <span><math><mi>G</mi><mo>−</mo><mi>P</mi></math></span> is connected, improving a previous connectivity bound of 10<em>m</em>.</p></div>","PeriodicalId":54865,"journal":{"name":"Journal of Combinatorial Theory Series B","volume":"169 ","pages":"Pages 211-232"},"PeriodicalIF":1.2000,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Linkages and removable paths avoiding vertices\",\"authors\":\"Xiying Du, Yanjia Li, Shijie Xie , Xingxing Yu\",\"doi\":\"10.1016/j.jctb.2024.06.006\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>A graph <em>G</em> is <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mi>m</mi><mo>)</mo></math></span>-linked if, for any distinct vertices <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> in <em>G</em>, there exist disjoint connected subgraphs <span><math><mi>A</mi><mo>,</mo><mi>B</mi></math></span> of <em>G</em> such that <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>∈</mo><mi>V</mi><mo>(</mo><mi>A</mi><mo>)</mo></math></span> and <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>∈</mo><mi>V</mi><mo>(</mo><mi>B</mi><mo>)</mo></math></span>. A fundamental result in structural graph theory is the characterization of <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mn>2</mn><mo>)</mo></math></span>-linked graphs. It appears to be difficult to characterize <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mi>m</mi><mo>)</mo></math></span>-linked graphs for <span><math><mi>m</mi><mo>≥</mo><mn>3</mn></math></span>. In this paper, we provide a partial characterization of <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mi>m</mi><mo>)</mo></math></span>-linked graphs. This implies that every <span><math><mo>(</mo><mn>2</mn><mi>m</mi><mo>+</mo><mn>2</mn><mo>)</mo></math></span>-connected graphs <em>G</em> is <span><math><mo>(</mo><mn>2</mn><mo>,</mo><mi>m</mi><mo>)</mo></math></span>-linked and for any distinct vertices <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> of <em>G</em>, there is a path <em>P</em> in <em>G</em> between <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> and avoiding <span><math><mo>{</mo><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>}</mo></math></span> such that <span><math><mi>G</mi><mo>−</mo><mi>P</mi></math></span> is connected, improving a previous connectivity bound of 10<em>m</em>.</p></div>\",\"PeriodicalId\":54865,\"journal\":{\"name\":\"Journal of Combinatorial Theory Series B\",\"volume\":\"169 \",\"pages\":\"Pages 211-232\"},\"PeriodicalIF\":1.2000,\"publicationDate\":\"2024-07-15\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Combinatorial Theory Series B\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0095895624000595\",\"RegionNum\":1,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Combinatorial Theory Series B","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0095895624000595","RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
摘要
如果对于 G 中任何不同的顶点 a1,...,am,b1,b2,存在 G 的互不相交的连通子图 A,B,使得 a1,...,am∈V(A)和 b1,b2∈V(B),则图 G 是 (2,m)-linked 的。结构图理论的一个基本结果是(2,2)连接图的特征描述。要描述 m≥3 的 (2,m) 链接图似乎很难。本文提供了 (2,m) 链接图的部分特征。这意味着每个 (2m+2)-linkected graphs G 都是 (2,m)-linked 的,并且对于 G 的任何不同顶点 a1,...,am,b1,b2,G 中都存在一条路径 P,该路径 P 位于 b1 和 b2 之间,并避开 {a1,...,am},这样 G-P 就是连通的,从而改善了之前 10m 的连通性约束。
A graph G is -linked if, for any distinct vertices in G, there exist disjoint connected subgraphs of G such that and . A fundamental result in structural graph theory is the characterization of -linked graphs. It appears to be difficult to characterize -linked graphs for . In this paper, we provide a partial characterization of -linked graphs. This implies that every -connected graphs G is -linked and for any distinct vertices of G, there is a path P in G between and and avoiding such that is connected, improving a previous connectivity bound of 10m.
期刊介绍:
The Journal of Combinatorial Theory publishes original mathematical research dealing with theoretical and physical aspects of the study of finite and discrete structures in all branches of science. Series B is concerned primarily with graph theory and matroid theory and is a valuable tool for mathematicians and computer scientists.