József Balogh , Ramon I. Garcia , Lina Li , Adam Zsolt Wagner
{"title":"集合的相交族通常是平凡的","authors":"József Balogh , Ramon I. Garcia , Lina Li , Adam Zsolt Wagner","doi":"10.1016/j.jctb.2023.09.002","DOIUrl":null,"url":null,"abstract":"<div><p>A family of subsets of <span><math><mo>[</mo><mi>n</mi><mo>]</mo></math></span> is <em>intersecting</em> if every pair of its sets intersects. Determining the structure of large intersecting families is a central problem in extremal combinatorics. Frankl–Kupavskii and Balogh–Das–Liu–Sharifzadeh–Tran showed that for <span><math><mi>n</mi><mo>≥</mo><mn>2</mn><mi>k</mi><mo>+</mo><mi>c</mi><msqrt><mrow><mi>k</mi><mi>ln</mi><mo></mo><mi>k</mi></mrow></msqrt></math></span>, almost all <em>k</em>-uniform intersecting families are stars. Improving their result, we show that the same conclusion holds for <span><math><mi>n</mi><mo>≥</mo><mn>2</mn><mi>k</mi><mo>+</mo><mn>100</mn><mi>ln</mi><mo></mo><mi>k</mi></math></span>. Our proof uses, among others, the graph container method and the Das–Tran removal lemma.</p></div>","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":null,"pages":null},"PeriodicalIF":16.4000,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"4","resultStr":"{\"title\":\"Intersecting families of sets are typically trivial\",\"authors\":\"József Balogh , Ramon I. Garcia , Lina Li , Adam Zsolt Wagner\",\"doi\":\"10.1016/j.jctb.2023.09.002\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>A family of subsets of <span><math><mo>[</mo><mi>n</mi><mo>]</mo></math></span> is <em>intersecting</em> if every pair of its sets intersects. Determining the structure of large intersecting families is a central problem in extremal combinatorics. Frankl–Kupavskii and Balogh–Das–Liu–Sharifzadeh–Tran showed that for <span><math><mi>n</mi><mo>≥</mo><mn>2</mn><mi>k</mi><mo>+</mo><mi>c</mi><msqrt><mrow><mi>k</mi><mi>ln</mi><mo></mo><mi>k</mi></mrow></msqrt></math></span>, almost all <em>k</em>-uniform intersecting families are stars. Improving their result, we show that the same conclusion holds for <span><math><mi>n</mi><mo>≥</mo><mn>2</mn><mi>k</mi><mo>+</mo><mn>100</mn><mi>ln</mi><mo></mo><mi>k</mi></math></span>. Our proof uses, among others, the graph container method and the Das–Tran removal lemma.</p></div>\",\"PeriodicalId\":1,\"journal\":{\"name\":\"Accounts of Chemical Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":16.4000,\"publicationDate\":\"2023-09-20\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"4\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Accounts of Chemical Research\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0095895623000709\",\"RegionNum\":1,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Accounts of Chemical Research","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0095895623000709","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
Intersecting families of sets are typically trivial
A family of subsets of is intersecting if every pair of its sets intersects. Determining the structure of large intersecting families is a central problem in extremal combinatorics. Frankl–Kupavskii and Balogh–Das–Liu–Sharifzadeh–Tran showed that for , almost all k-uniform intersecting families are stars. Improving their result, we show that the same conclusion holds for . Our proof uses, among others, the graph container method and the Das–Tran removal lemma.
期刊介绍:
Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance.
Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.