{"title":"Transversals in a collection of stars or generic trees","authors":"Ethan Y.H. Li , Luyi Li , Ping Li","doi":"10.1016/j.disc.2025.114836","DOIUrl":null,"url":null,"abstract":"<div><div>Let <span><math><mi>F</mi></math></span> be a fixed collection of graphs on vertex set <em>V</em> and let <span><math><mi>G</mi></math></span> be a collection of elements in <span><math><mi>F</mi></math></span>. We investigate the transversal problem of finding the maximum value of <span><math><mo>|</mo><mi>G</mi><mo>|</mo></math></span> when <span><math><mi>G</mi></math></span> contains no rainbow element in <span><math><mi>F</mi></math></span>. In this paper, we determine the exact values and characterize all the extremal cases of <span><math><mi>G</mi></math></span> when <span><math><mi>F</mi></math></span> is a collection of stars or generic trees with the same order, respectively.</div></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"349 3","pages":"Article 114836"},"PeriodicalIF":0.7000,"publicationDate":"2025-10-10","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/S0012365X25004443","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
Let be a fixed collection of graphs on vertex set V and let be a collection of elements in . We investigate the transversal problem of finding the maximum value of when contains no rainbow element in . In this paper, we determine the exact values and characterize all the extremal cases of when is a collection of stars or generic trees with the same order, respectively.
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.