{"title":"粗糙门格尔猜想的反例","authors":"Tung Nguyen , Alex Scott , Paul Seymour","doi":"10.1016/j.jctb.2025.01.004","DOIUrl":null,"url":null,"abstract":"<div><div>Menger's well-known theorem from 1927 characterizes when it is possible to find <em>k</em> vertex-disjoint paths between two sets of vertices in a graph <em>G</em>. Recently, Georgakopoulos and Papasoglu and, independently, Albrechtsen, Huynh, Jacobs, Knappe and Wollan conjectured a coarse analogue of Menger's theorem, when the <em>k</em> paths are required to be pairwise at some distance at least <em>d</em>. The result is known for <span><math><mi>k</mi><mo>≤</mo><mn>2</mn></math></span>, but we will show that it is false for all <span><math><mi>k</mi><mo>≥</mo><mn>3</mn></math></span>, even if <em>G</em> is constrained to have maximum degree at most three. We also give a simpler proof of the result when <span><math><mi>k</mi><mo>=</mo><mn>2</mn></math></span>.</div></div>","PeriodicalId":54865,"journal":{"name":"Journal of Combinatorial Theory Series B","volume":"173 ","pages":"Pages 68-82"},"PeriodicalIF":1.2000,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"A counterexample to the coarse Menger conjecture\",\"authors\":\"Tung Nguyen , Alex Scott , Paul Seymour\",\"doi\":\"10.1016/j.jctb.2025.01.004\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Menger's well-known theorem from 1927 characterizes when it is possible to find <em>k</em> vertex-disjoint paths between two sets of vertices in a graph <em>G</em>. Recently, Georgakopoulos and Papasoglu and, independently, Albrechtsen, Huynh, Jacobs, Knappe and Wollan conjectured a coarse analogue of Menger's theorem, when the <em>k</em> paths are required to be pairwise at some distance at least <em>d</em>. The result is known for <span><math><mi>k</mi><mo>≤</mo><mn>2</mn></math></span>, but we will show that it is false for all <span><math><mi>k</mi><mo>≥</mo><mn>3</mn></math></span>, even if <em>G</em> is constrained to have maximum degree at most three. We also give a simpler proof of the result when <span><math><mi>k</mi><mo>=</mo><mn>2</mn></math></span>.</div></div>\",\"PeriodicalId\":54865,\"journal\":{\"name\":\"Journal of Combinatorial Theory Series B\",\"volume\":\"173 \",\"pages\":\"Pages 68-82\"},\"PeriodicalIF\":1.2000,\"publicationDate\":\"2025-02-13\",\"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/S0095895625000061\",\"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/S0095895625000061","RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
Menger's well-known theorem from 1927 characterizes when it is possible to find k vertex-disjoint paths between two sets of vertices in a graph G. Recently, Georgakopoulos and Papasoglu and, independently, Albrechtsen, Huynh, Jacobs, Knappe and Wollan conjectured a coarse analogue of Menger's theorem, when the k paths are required to be pairwise at some distance at least d. The result is known for , but we will show that it is false for all , even if G is constrained to have maximum degree at most three. We also give a simpler proof of the result when .
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.