{"title":"Proof of a conjecture on connectivity keeping odd paths in k-connected bipartite graphs","authors":"Qing Yang, Yingzhi Tian","doi":"10.1016/j.disc.2025.114476","DOIUrl":null,"url":null,"abstract":"<div><div>Luo, Tian and Wu (2022) conjectured that for any tree <em>T</em> with bipartition <em>X</em> and <em>Y</em>, every <em>k</em>-connected bipartite graph <em>G</em> with minimum degree at least <span><math><mi>k</mi><mo>+</mo><mi>t</mi></math></span>, where <span><math><mi>t</mi><mo>=</mo><mi>max</mi><mo></mo><mo>{</mo><mo>|</mo><mi>X</mi><mo>|</mo><mo>,</mo><mo>|</mo><mi>Y</mi><mo>|</mo><mo>}</mo></math></span>, contains a tree <span><math><msup><mrow><mi>T</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>≅</mo><mi>T</mi></math></span> such that <span><math><mi>G</mi><mo>−</mo><mi>V</mi><mo>(</mo><msup><mrow><mi>T</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>)</mo></math></span> is still <em>k</em>-connected. Note that <span><math><mi>t</mi><mo>=</mo><mo>⌈</mo><mfrac><mrow><mi>m</mi></mrow><mrow><mn>2</mn></mrow></mfrac><mo>⌉</mo></math></span> when the tree <em>T</em> is the path with order <em>m</em>. In this paper, we prove that every <em>k</em>-connected bipartite graph <em>G</em> with minimum degree at least <span><math><mi>k</mi><mo>+</mo><mo>⌈</mo><mfrac><mrow><mi>m</mi><mo>+</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>⌉</mo></math></span> contains a path <em>P</em> of order <em>m</em> such that <span><math><mi>G</mi><mo>−</mo><mi>V</mi><mo>(</mo><mi>P</mi><mo>)</mo></math></span> remains <em>k</em>-connected. This shows that the conjecture is true for paths with odd order. For paths with even order, the minimum degree bound in this paper is the bound in the conjecture plus one.</div></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"348 8","pages":"Article 114476"},"PeriodicalIF":0.7000,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0012365X25000846","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
Luo, Tian and Wu (2022) conjectured that for any tree T with bipartition X and Y, every k-connected bipartite graph G with minimum degree at least , where , contains a tree such that is still k-connected. Note that when the tree T is the path with order m. In this paper, we prove that every k-connected bipartite graph G with minimum degree at least contains a path P of order m such that remains k-connected. This shows that the conjecture is true for paths with odd order. For paths with even order, the minimum degree bound in this paper is the bound in the conjecture plus one.
期刊介绍:
Discrete Mathematics provides a common forum for significant research in many areas of discrete mathematics and combinatorics. Among the fields covered by Discrete Mathematics are graph and hypergraph theory, enumeration, coding theory, block designs, the combinatorics of partially ordered sets, extremal set theory, matroid theory, algebraic combinatorics, discrete geometry, matrices, and discrete probability theory.
Items in the journal include research articles (Contributions or Notes, depending on length) and survey/expository articles (Perspectives). Efforts are made to process the submission of Notes (short articles) quickly. The Perspectives section features expository articles accessible to a broad audience that cast new light or present unifying points of view on well-known or insufficiently-known topics.