{"title":"欧拉图的路径分解","authors":"Yanan Chu , Yan Wang","doi":"10.1016/j.disc.2025.114830","DOIUrl":null,"url":null,"abstract":"<div><div>Gallai's conjecture asserts that every connected graph on <em>n</em> vertices can be decomposed into <span><math><mfrac><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></math></span> paths. For general graphs (possibly disconnected), it was proved that every graph on <em>n</em> vertices can be decomposed into <span><math><mfrac><mrow><mn>2</mn><mi>n</mi></mrow><mrow><mn>3</mn></mrow></mfrac></math></span> paths. This is also best possible (consider the graphs consisting of vertex-disjoint triangles). Lovász showed that every <em>n</em>-vertex graph with at most one vertex of even degree can be decomposed into <span><math><mfrac><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></mfrac></math></span> paths. However, Gallai's conjecture is difficult for graphs with many vertices of even degrees. Favaron and Kouider verified Gallai's conjecture for all Eulerian graphs with maximum degree at most 4. In this paper, we show if <em>G</em> is an Eulerian graph on <span><math><mi>n</mi><mo>≥</mo><mn>4</mn></math></span> vertices and the distance between any two triangles in <em>G</em> is at least 3, then <em>G</em> can be decomposed into at most <span><math><mfrac><mrow><mn>3</mn><mi>n</mi></mrow><mrow><mn>5</mn></mrow></mfrac></math></span> paths.</div></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"349 2","pages":"Article 114830"},"PeriodicalIF":0.7000,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Path decompositions of Eulerian graphs\",\"authors\":\"Yanan Chu , Yan Wang\",\"doi\":\"10.1016/j.disc.2025.114830\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Gallai's conjecture asserts that every connected graph on <em>n</em> vertices can be decomposed into <span><math><mfrac><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></math></span> paths. For general graphs (possibly disconnected), it was proved that every graph on <em>n</em> vertices can be decomposed into <span><math><mfrac><mrow><mn>2</mn><mi>n</mi></mrow><mrow><mn>3</mn></mrow></mfrac></math></span> paths. This is also best possible (consider the graphs consisting of vertex-disjoint triangles). Lovász showed that every <em>n</em>-vertex graph with at most one vertex of even degree can be decomposed into <span><math><mfrac><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></mfrac></math></span> paths. However, Gallai's conjecture is difficult for graphs with many vertices of even degrees. Favaron and Kouider verified Gallai's conjecture for all Eulerian graphs with maximum degree at most 4. In this paper, we show if <em>G</em> is an Eulerian graph on <span><math><mi>n</mi><mo>≥</mo><mn>4</mn></math></span> vertices and the distance between any two triangles in <em>G</em> is at least 3, then <em>G</em> can be decomposed into at most <span><math><mfrac><mrow><mn>3</mn><mi>n</mi></mrow><mrow><mn>5</mn></mrow></mfrac></math></span> paths.</div></div>\",\"PeriodicalId\":50572,\"journal\":{\"name\":\"Discrete Mathematics\",\"volume\":\"349 2\",\"pages\":\"Article 114830\"},\"PeriodicalIF\":0.7000,\"publicationDate\":\"2025-10-03\",\"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/S0012365X25004388\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0012365X25004388","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
Gallai's conjecture asserts that every connected graph on n vertices can be decomposed into paths. For general graphs (possibly disconnected), it was proved that every graph on n vertices can be decomposed into paths. This is also best possible (consider the graphs consisting of vertex-disjoint triangles). Lovász showed that every n-vertex graph with at most one vertex of even degree can be decomposed into paths. However, Gallai's conjecture is difficult for graphs with many vertices of even degrees. Favaron and Kouider verified Gallai's conjecture for all Eulerian graphs with maximum degree at most 4. In this paper, we show if G is an Eulerian graph on vertices and the distance between any two triangles in G is at least 3, then G can be decomposed into at most paths.
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.