拉姆齐数和一般厄尔多斯-罗杰斯函数

IF 0.7 3区 数学 Q2 MATHEMATICS
{"title":"拉姆齐数和一般厄尔多斯-罗杰斯函数","authors":"","doi":"10.1016/j.disc.2024.114203","DOIUrl":null,"url":null,"abstract":"<div><p>Given a graph <em>F</em>, let <span><math><mi>L</mi><mo>(</mo><mi>F</mi><mo>)</mo></math></span> be a fixed finite family of graphs consisting of a <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span> and some bipartite graphs relying on an <em>s</em>-partite subgraph partitioning of edges of <em>F</em>. Define <span><math><mo>(</mo><mi>m</mi><mo>,</mo><mi>n</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></math></span>-graph by an <span><math><mi>m</mi><mo>×</mo><mi>n</mi></math></span> bipartite graph with <span><math><mi>n</mi><mo>≥</mo><mi>m</mi></math></span> such that all vertices in the part of size <em>n</em> have degree <em>a</em> and all vertices in the part of size <em>m</em> have degree <span><math><mi>b</mi><mo>≥</mo><mi>a</mi></math></span>. In this paper, building upon the work of Janzer and Sudakov (2023<sup>+</sup>) and combining with the idea of Conlon, Mattheus, Mubayi and Verstraëte (2023<sup>+</sup>) we obtain that for each <span><math><mi>s</mi><mo>≥</mo><mn>2</mn></math></span>, if there exists an <span><math><mi>L</mi><mo>(</mo><mi>F</mi><mo>)</mo></math></span>-free <span><math><mo>(</mo><mi>m</mi><mo>,</mo><mi>n</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></math></span>-graph, then there exists an <em>F</em>-free graph <span><math><msup><mrow><mi>H</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span> with at least <span><math><mi>n</mi><msup><mrow><mi>a</mi></mrow><mrow><mo>−</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mi>s</mi><mo>−</mo><mn>1</mn></mrow></mfrac></mrow></msup><mo>−</mo><mn>1</mn></math></span> vertices in which every vertex subset of size <span><math><mi>m</mi><msup><mrow><mi>a</mi></mrow><mrow><mo>−</mo><mfrac><mrow><mi>s</mi></mrow><mrow><mi>s</mi><mo>−</mo><mn>1</mn></mrow></mfrac></mrow></msup><msup><mrow><mi>log</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>⁡</mo><mo>(</mo><mi>a</mi><mi>n</mi><mo>)</mo></math></span> contains a copy of <span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span>. As applications, we obtain some upper bounds of general Erdős-Rogers functions for some special graphs of <em>F</em>. Moreover, we obtain the multicolor Ramsey numbers <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>k</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>;</mo><mi>t</mi><mo>)</mo><mo>=</mo><mover><mrow><mi>Ω</mi></mrow><mrow><mo>˜</mo></mrow></mover><mo>(</mo><msup><mrow><mi>t</mi></mrow><mrow><mfrac><mrow><mn>3</mn><mi>k</mi></mrow><mrow><mn>7</mn></mrow></mfrac><mo>+</mo><mn>1</mn></mrow></msup><mo>)</mo></math></span> and <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>k</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>7</mn></mrow></msub><mo>;</mo><mi>t</mi><mo>)</mo><mo>=</mo><mover><mrow><mi>Ω</mi></mrow><mrow><mo>˜</mo></mrow></mover><mo>(</mo><msup><mrow><mi>t</mi></mrow><mrow><mfrac><mrow><mi>k</mi></mrow><mrow><mn>4</mn></mrow></mfrac><mo>+</mo><mn>1</mn></mrow></msup><mo>)</mo></math></span>, which improve that by Xu and Ge (2022) <span><span>[24]</span></span>.</p></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":null,"pages":null},"PeriodicalIF":0.7000,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Ramsey numbers and a general Erdős-Rogers function\",\"authors\":\"\",\"doi\":\"10.1016/j.disc.2024.114203\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Given a graph <em>F</em>, let <span><math><mi>L</mi><mo>(</mo><mi>F</mi><mo>)</mo></math></span> be a fixed finite family of graphs consisting of a <span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span> and some bipartite graphs relying on an <em>s</em>-partite subgraph partitioning of edges of <em>F</em>. Define <span><math><mo>(</mo><mi>m</mi><mo>,</mo><mi>n</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></math></span>-graph by an <span><math><mi>m</mi><mo>×</mo><mi>n</mi></math></span> bipartite graph with <span><math><mi>n</mi><mo>≥</mo><mi>m</mi></math></span> such that all vertices in the part of size <em>n</em> have degree <em>a</em> and all vertices in the part of size <em>m</em> have degree <span><math><mi>b</mi><mo>≥</mo><mi>a</mi></math></span>. In this paper, building upon the work of Janzer and Sudakov (2023<sup>+</sup>) and combining with the idea of Conlon, Mattheus, Mubayi and Verstraëte (2023<sup>+</sup>) we obtain that for each <span><math><mi>s</mi><mo>≥</mo><mn>2</mn></math></span>, if there exists an <span><math><mi>L</mi><mo>(</mo><mi>F</mi><mo>)</mo></math></span>-free <span><math><mo>(</mo><mi>m</mi><mo>,</mo><mi>n</mi><mo>,</mo><mi>a</mi><mo>,</mo><mi>b</mi><mo>)</mo></math></span>-graph, then there exists an <em>F</em>-free graph <span><math><msup><mrow><mi>H</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span> with at least <span><math><mi>n</mi><msup><mrow><mi>a</mi></mrow><mrow><mo>−</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mi>s</mi><mo>−</mo><mn>1</mn></mrow></mfrac></mrow></msup><mo>−</mo><mn>1</mn></math></span> vertices in which every vertex subset of size <span><math><mi>m</mi><msup><mrow><mi>a</mi></mrow><mrow><mo>−</mo><mfrac><mrow><mi>s</mi></mrow><mrow><mi>s</mi><mo>−</mo><mn>1</mn></mrow></mfrac></mrow></msup><msup><mrow><mi>log</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>⁡</mo><mo>(</mo><mi>a</mi><mi>n</mi><mo>)</mo></math></span> contains a copy of <span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span>. As applications, we obtain some upper bounds of general Erdős-Rogers functions for some special graphs of <em>F</em>. Moreover, we obtain the multicolor Ramsey numbers <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>k</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>;</mo><mi>t</mi><mo>)</mo><mo>=</mo><mover><mrow><mi>Ω</mi></mrow><mrow><mo>˜</mo></mrow></mover><mo>(</mo><msup><mrow><mi>t</mi></mrow><mrow><mfrac><mrow><mn>3</mn><mi>k</mi></mrow><mrow><mn>7</mn></mrow></mfrac><mo>+</mo><mn>1</mn></mrow></msup><mo>)</mo></math></span> and <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>k</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>(</mo><msub><mrow><mi>C</mi></mrow><mrow><mn>7</mn></mrow></msub><mo>;</mo><mi>t</mi><mo>)</mo><mo>=</mo><mover><mrow><mi>Ω</mi></mrow><mrow><mo>˜</mo></mrow></mover><mo>(</mo><msup><mrow><mi>t</mi></mrow><mrow><mfrac><mrow><mi>k</mi></mrow><mrow><mn>4</mn></mrow></mfrac><mo>+</mo><mn>1</mn></mrow></msup><mo>)</mo></math></span>, which improve that by Xu and Ge (2022) <span><span>[24]</span></span>.</p></div>\",\"PeriodicalId\":50572,\"journal\":{\"name\":\"Discrete Mathematics\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.7000,\"publicationDate\":\"2024-08-12\",\"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/S0012365X24003340\",\"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/S0012365X24003340","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

摘要

给定一个图 F,让 L(F) 是一个固定的有限图族,由一个 C4 和一些依赖于 F 边的 s 部分子图分割的双部分图组成。定义(m,n,a,b)-图为 m×n 双部分图,n≥m,使得大小为 n 的部分中的所有顶点的度数为 a,大小为 m 的部分中的所有顶点的度数为 b≥a。本文以 Janzer 和 Sudakov (2023+) 的研究为基础,结合 Conlon、Mattheus、Mubayi 和 Verstraëte (2023+) 的想法,得出对于每个 s≥2,如果存在一个无 L(F)-free (m,n,a,b)-graph 图,那么存在一个至少有 na-1s-1-1 个顶点的无 F 图 H⁎,其中每个大小为 ma-ss-1log3(an) 的顶点子集都包含 Ks 的副本。此外,我们还得到了多色拉姆齐数 rk+1(C5;t)=Ω˜(t3k7+1) 和 rk+1(C7;t)=Ω˜(tk4+1) ,它们改进了徐和葛(2022)的结果[24]。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Ramsey numbers and a general Erdős-Rogers function

Given a graph F, let L(F) be a fixed finite family of graphs consisting of a C4 and some bipartite graphs relying on an s-partite subgraph partitioning of edges of F. Define (m,n,a,b)-graph by an m×n bipartite graph with nm such that all vertices in the part of size n have degree a and all vertices in the part of size m have degree ba. In this paper, building upon the work of Janzer and Sudakov (2023+) and combining with the idea of Conlon, Mattheus, Mubayi and Verstraëte (2023+) we obtain that for each s2, if there exists an L(F)-free (m,n,a,b)-graph, then there exists an F-free graph H with at least na1s11 vertices in which every vertex subset of size mass1log3(an) contains a copy of Ks. As applications, we obtain some upper bounds of general Erdős-Rogers functions for some special graphs of F. Moreover, we obtain the multicolor Ramsey numbers rk+1(C5;t)=Ω˜(t3k7+1) and rk+1(C7;t)=Ω˜(tk4+1), which improve that by Xu and Ge (2022) [24].

求助全文
通过发布文献求助,成功后即可免费获取论文全文。 去求助
来源期刊
Discrete Mathematics
Discrete Mathematics 数学-数学
CiteScore
1.50
自引率
12.50%
发文量
424
审稿时长
6 months
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.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信