{"title":"到处都是不平衡的配置","authors":"David Conlon , Jeck Lim","doi":"10.1016/j.aim.2025.110445","DOIUrl":null,"url":null,"abstract":"<div><div>An old problem in discrete geometry, originating with Kupitz, asks whether there is a fixed natural number <em>k</em> such that every finite set of points in the plane has a line through at least two of its points where the number of points on either side of this line differ by at most <em>k</em>. We give a negative answer to a natural variant of this problem, showing that for every natural number <em>k</em> there exists a finite set of points in the plane together with a pseudoline arrangement such that each pseudoline contains at least two points and there is a pseudoline through any pair of points where the number of points on either side of each pseudoline differ by at least <em>k</em>. Moreover, we may find such a configuration with at most <span><math><msup><mrow><mn>2</mn></mrow><mrow><msup><mrow><mn>2</mn></mrow><mrow><mi>c</mi><mi>k</mi></mrow></msup></mrow></msup></math></span> points, which, by a result of Pinchasi, is best possible up to the value of the constant <em>c</em>.</div></div>","PeriodicalId":50860,"journal":{"name":"Advances in Mathematics","volume":"480 ","pages":"Article 110445"},"PeriodicalIF":1.5000,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Everywhere unbalanced configurations\",\"authors\":\"David Conlon , Jeck Lim\",\"doi\":\"10.1016/j.aim.2025.110445\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>An old problem in discrete geometry, originating with Kupitz, asks whether there is a fixed natural number <em>k</em> such that every finite set of points in the plane has a line through at least two of its points where the number of points on either side of this line differ by at most <em>k</em>. We give a negative answer to a natural variant of this problem, showing that for every natural number <em>k</em> there exists a finite set of points in the plane together with a pseudoline arrangement such that each pseudoline contains at least two points and there is a pseudoline through any pair of points where the number of points on either side of each pseudoline differ by at least <em>k</em>. Moreover, we may find such a configuration with at most <span><math><msup><mrow><mn>2</mn></mrow><mrow><msup><mrow><mn>2</mn></mrow><mrow><mi>c</mi><mi>k</mi></mrow></msup></mrow></msup></math></span> points, which, by a result of Pinchasi, is best possible up to the value of the constant <em>c</em>.</div></div>\",\"PeriodicalId\":50860,\"journal\":{\"name\":\"Advances in Mathematics\",\"volume\":\"480 \",\"pages\":\"Article 110445\"},\"PeriodicalIF\":1.5000,\"publicationDate\":\"2025-07-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Advances in Mathematics\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0001870825003433\",\"RegionNum\":1,\"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":"Advances in Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0001870825003433","RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
An old problem in discrete geometry, originating with Kupitz, asks whether there is a fixed natural number k such that every finite set of points in the plane has a line through at least two of its points where the number of points on either side of this line differ by at most k. We give a negative answer to a natural variant of this problem, showing that for every natural number k there exists a finite set of points in the plane together with a pseudoline arrangement such that each pseudoline contains at least two points and there is a pseudoline through any pair of points where the number of points on either side of each pseudoline differ by at least k. Moreover, we may find such a configuration with at most points, which, by a result of Pinchasi, is best possible up to the value of the constant c.
期刊介绍:
Emphasizing contributions that represent significant advances in all areas of pure mathematics, Advances in Mathematics provides research mathematicians with an effective medium for communicating important recent developments in their areas of specialization to colleagues and to scientists in related disciplines.