{"title":"An oriented discrepancy version of Dirac's theorem","authors":"Andrea Freschi, Allan Lo","doi":"10.1016/j.jctb.2024.06.008","DOIUrl":null,"url":null,"abstract":"<div><p>The study of graph discrepancy problems, initiated by Erdős in the 1960s, has received renewed attention in recent years. In general, given a 2-edge-coloured graph <em>G</em>, one is interested in embedding a copy of a graph <em>H</em> in <em>G</em> with large discrepancy (i.e. the copy of <em>H</em> contains significantly more than half of its edges in one colour).</p><p>Motivated by this line of research, Gishboliner, Krivelevich and Michaeli considered an oriented version of graph discrepancy for Hamilton cycles. In particular, they conjectured the following generalisation of Dirac's theorem: if <em>G</em> is an oriented graph on <span><math><mi>n</mi><mo>≥</mo><mn>3</mn></math></span> vertices with <span><math><mi>δ</mi><mo>(</mo><mi>G</mi><mo>)</mo><mo>≥</mo><mi>n</mi><mo>/</mo><mn>2</mn></math></span>, then <em>G</em> contains a Hamilton cycle with at least <span><math><mi>δ</mi><mo>(</mo><mi>G</mi><mo>)</mo></math></span> edges pointing forwards. In this paper, we present a full resolution to this conjecture.</p></div>","PeriodicalId":54865,"journal":{"name":"Journal of Combinatorial Theory Series B","volume":"169 ","pages":"Pages 338-351"},"PeriodicalIF":1.2000,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0095895624000571/pdfft?md5=c4578c27cd9e214edf177c194b1972bb&pid=1-s2.0-S0095895624000571-main.pdf","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/S0095895624000571","RegionNum":1,"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
Abstract
The study of graph discrepancy problems, initiated by Erdős in the 1960s, has received renewed attention in recent years. In general, given a 2-edge-coloured graph G, one is interested in embedding a copy of a graph H in G with large discrepancy (i.e. the copy of H contains significantly more than half of its edges in one colour).
Motivated by this line of research, Gishboliner, Krivelevich and Michaeli considered an oriented version of graph discrepancy for Hamilton cycles. In particular, they conjectured the following generalisation of Dirac's theorem: if G is an oriented graph on vertices with , then G contains a Hamilton cycle with at least edges pointing forwards. In this paper, we present a full resolution to this conjecture.
图差异问题的研究由 Erdős 在 20 世纪 60 年代发起,近年来再次受到关注。一般来说,给定一个两边着色的图 G,人们感兴趣的是在 G 中嵌入一个具有较大差异的图 H 副本(即 H 副本含有明显超过一半的边为一种颜色)。特别是,他们猜想了狄拉克定理的以下概括:如果 G 是 n≥3 个顶点上的δ(G)≥n/2 的定向图,那么 G 包含一个至少有 δ(G) 条边指向前方的汉密尔顿循环。在本文中,我们提出了这一猜想的完整解决方案。
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.