{"title":"Rn$\\mathbb {R}^n$中的行并集","authors":"Joshua Zahl","doi":"10.1112/mtk.12190","DOIUrl":null,"url":null,"abstract":"<p>We prove a conjecture of D. Oberlin on the dimension of unions of lines in <math>\n <semantics>\n <msup>\n <mi>R</mi>\n <mi>n</mi>\n </msup>\n <annotation>$\\mathbb {R}^n$</annotation>\n </semantics></math>. If <math>\n <semantics>\n <mrow>\n <mi>d</mi>\n <mo>⩾</mo>\n <mn>1</mn>\n </mrow>\n <annotation>$d\\geqslant 1$</annotation>\n </semantics></math> is an integer, <math>\n <semantics>\n <mrow>\n <mn>0</mn>\n <mo>⩽</mo>\n <mi>β</mi>\n <mo>⩽</mo>\n <mn>1</mn>\n </mrow>\n <annotation>$0\\leqslant \\beta \\leqslant 1$</annotation>\n </semantics></math>, and <i>L</i> is a set of lines in <math>\n <semantics>\n <msup>\n <mi>R</mi>\n <mi>n</mi>\n </msup>\n <annotation>$\\mathbb {R}^n$</annotation>\n </semantics></math> with Hausdorff dimension at least <math>\n <semantics>\n <mrow>\n <mn>2</mn>\n <mo>(</mo>\n <mi>d</mi>\n <mo>−</mo>\n <mn>1</mn>\n <mo>)</mo>\n <mo>+</mo>\n <mi>β</mi>\n </mrow>\n <annotation>$2(d-1)+\\beta$</annotation>\n </semantics></math>, then the union of the lines in <i>L</i> has Hausdorff dimension at least <math>\n <semantics>\n <mrow>\n <mi>d</mi>\n <mo>+</mo>\n <mi>β</mi>\n </mrow>\n <annotation>$d + \\beta$</annotation>\n </semantics></math>. Our proof combines a refined version of the multilinear Kakeya theorem by Carbery and Valdimarsson with the multilinear → linear argument of Bourgain and Guth.</p>","PeriodicalId":18463,"journal":{"name":"Mathematika","volume":null,"pages":null},"PeriodicalIF":0.8000,"publicationDate":"2023-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1112/mtk.12190","citationCount":"0","resultStr":"{\"title\":\"Unions of lines in \\n \\n \\n R\\n n\\n \\n $\\\\mathbb {R}^n$\",\"authors\":\"Joshua Zahl\",\"doi\":\"10.1112/mtk.12190\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>We prove a conjecture of D. Oberlin on the dimension of unions of lines in <math>\\n <semantics>\\n <msup>\\n <mi>R</mi>\\n <mi>n</mi>\\n </msup>\\n <annotation>$\\\\mathbb {R}^n$</annotation>\\n </semantics></math>. If <math>\\n <semantics>\\n <mrow>\\n <mi>d</mi>\\n <mo>⩾</mo>\\n <mn>1</mn>\\n </mrow>\\n <annotation>$d\\\\geqslant 1$</annotation>\\n </semantics></math> is an integer, <math>\\n <semantics>\\n <mrow>\\n <mn>0</mn>\\n <mo>⩽</mo>\\n <mi>β</mi>\\n <mo>⩽</mo>\\n <mn>1</mn>\\n </mrow>\\n <annotation>$0\\\\leqslant \\\\beta \\\\leqslant 1$</annotation>\\n </semantics></math>, and <i>L</i> is a set of lines in <math>\\n <semantics>\\n <msup>\\n <mi>R</mi>\\n <mi>n</mi>\\n </msup>\\n <annotation>$\\\\mathbb {R}^n$</annotation>\\n </semantics></math> with Hausdorff dimension at least <math>\\n <semantics>\\n <mrow>\\n <mn>2</mn>\\n <mo>(</mo>\\n <mi>d</mi>\\n <mo>−</mo>\\n <mn>1</mn>\\n <mo>)</mo>\\n <mo>+</mo>\\n <mi>β</mi>\\n </mrow>\\n <annotation>$2(d-1)+\\\\beta$</annotation>\\n </semantics></math>, then the union of the lines in <i>L</i> has Hausdorff dimension at least <math>\\n <semantics>\\n <mrow>\\n <mi>d</mi>\\n <mo>+</mo>\\n <mi>β</mi>\\n </mrow>\\n <annotation>$d + \\\\beta$</annotation>\\n </semantics></math>. Our proof combines a refined version of the multilinear Kakeya theorem by Carbery and Valdimarsson with the multilinear → linear argument of Bourgain and Guth.</p>\",\"PeriodicalId\":18463,\"journal\":{\"name\":\"Mathematika\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.8000,\"publicationDate\":\"2023-02-17\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://onlinelibrary.wiley.com/doi/epdf/10.1112/mtk.12190\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Mathematika\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1112/mtk.12190\",\"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":"Mathematika","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1112/mtk.12190","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
We prove a conjecture of D. Oberlin on the dimension of unions of lines in . If is an integer, , and L is a set of lines in with Hausdorff dimension at least , then the union of the lines in L has Hausdorff dimension at least . Our proof combines a refined version of the multilinear Kakeya theorem by Carbery and Valdimarsson with the multilinear → linear argument of Bourgain and Guth.
期刊介绍:
Mathematika publishes both pure and applied mathematical articles and has done so continuously since its founding by Harold Davenport in the 1950s. The traditional emphasis has been towards the purer side of mathematics but applied mathematics and articles addressing both aspects are equally welcome. The journal is published by the London Mathematical Society, on behalf of its owner University College London, and will continue to publish research papers of the highest mathematical quality.