{"title":"射影维增长界的最终紧性:二次度","authors":"Raf Cluckers , Itay Glazer","doi":"10.1016/j.jnt.2025.03.010","DOIUrl":null,"url":null,"abstract":"<div><div>In projective dimension growth results, one bounds the number of rational points of height at most <em>H</em> on an irreducible hypersurface in <span><math><msup><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow></msup></math></span> of degree <span><math><mi>d</mi><mo>></mo><mn>3</mn></math></span> by <span><math><mi>C</mi><mo>(</mo><mi>n</mi><mo>)</mo><msup><mrow><mi>d</mi></mrow><mrow><mn>2</mn></mrow></msup><msup><mrow><mi>H</mi></mrow><mrow><mi>n</mi><mo>−</mo><mn>1</mn></mrow></msup><msup><mrow><mo>(</mo><mi>log</mi><mo></mo><mi>H</mi><mo>)</mo></mrow><mrow><mi>M</mi><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msup></math></span>, where the quadratic dependence in <em>d</em> has been recently obtained by Binyamini, Cluckers and Kato in 2024 <span><span>[1]</span></span>. For these bounds, it was already shown by Castryck, Cluckers, Dittmann and Nguyen in 2020 <span><span>[3]</span></span> that one cannot do better than a linear dependence in <em>d</em>. In this paper we show that, for the mentioned projective dimension growth bounds, the quadratic dependence in <em>d</em> is eventually tight when <em>n</em> grows. More precisely the upper bounds cannot be better than <span><math><mi>c</mi><mo>(</mo><mi>n</mi><mo>)</mo><msup><mrow><mi>d</mi></mrow><mrow><mn>2</mn><mo>−</mo><mn>2</mn><mo>/</mo><mi>n</mi></mrow></msup><msup><mrow><mi>H</mi></mrow><mrow><mi>n</mi><mo>−</mo><mn>1</mn></mrow></msup></math></span> in general. Note that for affine dimension growth (for affine hypersurfaces of degree <em>d</em>, satisfying some extra conditions), the dependence on <em>d</em> is also quadratic by <span><span>[1]</span></span>, which is already known to be optimal by <span><span>[3]</span></span>. Our projective case thus complements the picture of tightness for dimension growth bounds for hypersurfaces.</div></div>","PeriodicalId":50110,"journal":{"name":"Journal of Number Theory","volume":"276 ","pages":"Pages 72-80"},"PeriodicalIF":0.6000,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Eventual tightness of projective dimension growth bounds: Quadratic in the degree\",\"authors\":\"Raf Cluckers , Itay Glazer\",\"doi\":\"10.1016/j.jnt.2025.03.010\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>In projective dimension growth results, one bounds the number of rational points of height at most <em>H</em> on an irreducible hypersurface in <span><math><msup><mrow><mi>P</mi></mrow><mrow><mi>n</mi></mrow></msup></math></span> of degree <span><math><mi>d</mi><mo>></mo><mn>3</mn></math></span> by <span><math><mi>C</mi><mo>(</mo><mi>n</mi><mo>)</mo><msup><mrow><mi>d</mi></mrow><mrow><mn>2</mn></mrow></msup><msup><mrow><mi>H</mi></mrow><mrow><mi>n</mi><mo>−</mo><mn>1</mn></mrow></msup><msup><mrow><mo>(</mo><mi>log</mi><mo></mo><mi>H</mi><mo>)</mo></mrow><mrow><mi>M</mi><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msup></math></span>, where the quadratic dependence in <em>d</em> has been recently obtained by Binyamini, Cluckers and Kato in 2024 <span><span>[1]</span></span>. For these bounds, it was already shown by Castryck, Cluckers, Dittmann and Nguyen in 2020 <span><span>[3]</span></span> that one cannot do better than a linear dependence in <em>d</em>. In this paper we show that, for the mentioned projective dimension growth bounds, the quadratic dependence in <em>d</em> is eventually tight when <em>n</em> grows. More precisely the upper bounds cannot be better than <span><math><mi>c</mi><mo>(</mo><mi>n</mi><mo>)</mo><msup><mrow><mi>d</mi></mrow><mrow><mn>2</mn><mo>−</mo><mn>2</mn><mo>/</mo><mi>n</mi></mrow></msup><msup><mrow><mi>H</mi></mrow><mrow><mi>n</mi><mo>−</mo><mn>1</mn></mrow></msup></math></span> in general. Note that for affine dimension growth (for affine hypersurfaces of degree <em>d</em>, satisfying some extra conditions), the dependence on <em>d</em> is also quadratic by <span><span>[1]</span></span>, which is already known to be optimal by <span><span>[3]</span></span>. Our projective case thus complements the picture of tightness for dimension growth bounds for hypersurfaces.</div></div>\",\"PeriodicalId\":50110,\"journal\":{\"name\":\"Journal of Number Theory\",\"volume\":\"276 \",\"pages\":\"Pages 72-80\"},\"PeriodicalIF\":0.6000,\"publicationDate\":\"2025-05-05\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Number Theory\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0022314X25001192\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Number Theory","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0022314X25001192","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
Eventual tightness of projective dimension growth bounds: Quadratic in the degree
In projective dimension growth results, one bounds the number of rational points of height at most H on an irreducible hypersurface in of degree by , where the quadratic dependence in d has been recently obtained by Binyamini, Cluckers and Kato in 2024 [1]. For these bounds, it was already shown by Castryck, Cluckers, Dittmann and Nguyen in 2020 [3] that one cannot do better than a linear dependence in d. In this paper we show that, for the mentioned projective dimension growth bounds, the quadratic dependence in d is eventually tight when n grows. More precisely the upper bounds cannot be better than in general. Note that for affine dimension growth (for affine hypersurfaces of degree d, satisfying some extra conditions), the dependence on d is also quadratic by [1], which is already known to be optimal by [3]. Our projective case thus complements the picture of tightness for dimension growth bounds for hypersurfaces.
期刊介绍:
The Journal of Number Theory (JNT) features selected research articles that represent the broad spectrum of interest in contemporary number theory and allied areas. A valuable resource for mathematicians, the journal provides an international forum for the publication of original research in this field.
The Journal of Number Theory is encouraging submissions of quality, long articles where most or all of the technical details are included. The journal now considers and welcomes also papers in Computational Number Theory.
Starting in May 2019, JNT will have a new format with 3 sections:
JNT Prime targets (possibly very long with complete proofs) high impact papers. Articles published in this section will be granted 1 year promotional open access.
JNT General Section is for shorter papers. We particularly encourage submission from junior researchers. Every attempt will be made to expedite the review process for such submissions.
Computational JNT . This section aims to provide a forum to disseminate contributions which make significant use of computer calculations to derive novel number theoretic results. There will be an online repository where supplementary codes and data can be stored.