Tara Abrishami , Eli Berger , Maria Chudnovsky , Shira Zerbib
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We prove this conjecture in the special case where <span><math><mi>G</mi></math></span> contains no sector wheel, namely, a pair <span><math><mrow><mo>(</mo><mi>H</mi><mo>,</mo><mi>w</mi><mo>)</mo></mrow></math></span> where <span><math><mi>H</mi></math></span> is an induced cycle of <span><math><mi>G</mi></math></span> and <span><math><mi>w</mi></math></span> is a vertex in <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>∖</mo><mi>V</mi><mrow><mo>(</mo><mi>H</mi><mo>)</mo></mrow></mrow></math></span> such that <span><math><mrow><mi>N</mi><mrow><mo>(</mo><mi>w</mi><mo>)</mo></mrow><mo>∩</mo><mi>H</mi></mrow></math></span> is either <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>H</mi><mo>)</mo></mrow></mrow></math></span> or a path with at least three vertices.</p></div>","PeriodicalId":50490,"journal":{"name":"European Journal of Combinatorics","volume":null,"pages":null},"PeriodicalIF":1.0000,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Graphs with no even holes and no sector wheels are the union of two chordal graphs\",\"authors\":\"Tara Abrishami , Eli Berger , Maria Chudnovsky , Shira Zerbib\",\"doi\":\"10.1016/j.ejc.2024.104035\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Sivaraman (2020) conjectured that if <span><math><mi>G</mi></math></span> is a graph with no induced even cycle then there exist sets <span><math><mrow><msub><mrow><mi>X</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>X</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>⊆</mo><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> satisfying <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>X</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>∪</mo><msub><mrow><mi>X</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span> such that the induced graphs <span><math><mrow><mi>G</mi><mrow><mo>[</mo><msub><mrow><mi>X</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>]</mo></mrow></mrow></math></span> and <span><math><mrow><mi>G</mi><mrow><mo>[</mo><msub><mrow><mi>X</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>]</mo></mrow></mrow></math></span> are both chordal. We prove this conjecture in the special case where <span><math><mi>G</mi></math></span> contains no sector wheel, namely, a pair <span><math><mrow><mo>(</mo><mi>H</mi><mo>,</mo><mi>w</mi><mo>)</mo></mrow></math></span> where <span><math><mi>H</mi></math></span> is an induced cycle of <span><math><mi>G</mi></math></span> and <span><math><mi>w</mi></math></span> is a vertex in <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>∖</mo><mi>V</mi><mrow><mo>(</mo><mi>H</mi><mo>)</mo></mrow></mrow></math></span> such that <span><math><mrow><mi>N</mi><mrow><mo>(</mo><mi>w</mi><mo>)</mo></mrow><mo>∩</mo><mi>H</mi></mrow></math></span> is either <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>H</mi><mo>)</mo></mrow></mrow></math></span> or a path with at least three vertices.</p></div>\",\"PeriodicalId\":50490,\"journal\":{\"name\":\"European Journal of Combinatorics\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2024-07-27\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"European Journal of Combinatorics\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0195669824001203\",\"RegionNum\":3,\"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":"European Journal of Combinatorics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0195669824001203","RegionNum":3,"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
Sivaraman (2020) 猜想,如果 G 是一个没有诱导偶数循环的图,那么存在满足 V(G)=X1∪X2 的集合 X1,X2⊆V(G) ,这样诱导图 G[X1] 和 G[X2] 都是弦图。我们在 G 不包含扇形轮的特殊情况下证明了这一猜想,即一对 (H,w),其中 H 是 G 的诱导循环,w 是 V(G)∖V(H) 中的顶点,使得 N(w)∩H 要么是 V(H),要么是至少有三个顶点的路径。
Graphs with no even holes and no sector wheels are the union of two chordal graphs
Sivaraman (2020) conjectured that if is a graph with no induced even cycle then there exist sets satisfying such that the induced graphs and are both chordal. We prove this conjecture in the special case where contains no sector wheel, namely, a pair where is an induced cycle of and is a vertex in such that is either or a path with at least three vertices.
期刊介绍:
The European Journal of Combinatorics is a high standard, international, bimonthly journal of pure mathematics, specializing in theories arising from combinatorial problems. The journal is primarily open to papers dealing with mathematical structures within combinatorics and/or establishing direct links between combinatorics and other branches of mathematics and the theories of computing. The journal includes full-length research papers on important topics.