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Convergence problem of multiple Fourier series and Gauss circle problem

Research Project

Project/Area Number 17K18731
Research Category

Grant-in-Aid for Challenging Research (Exploratory)

Allocation TypeMulti-year Fund
Research Field Analysis, Applied mathematics, and related fields
Research InstitutionIbaraki University

Principal Investigator

Nakai Eiichi  茨城大学, 理工学研究科(理学野), 教授 (60259900)

Co-Investigator(Kenkyū-buntansha) 倉坪 茂彦  弘前大学, 理工学研究科, 客員研究員 (50003512)
藤間 昌一  茨城大学, 理工学研究科(理学野), 教授 (00209082)
Project Period (FY) 2017-06-30 – 2022-03-31
Project Status Completed (Fiscal Year 2021)
Budget Amount *help
¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000)
Fiscal Year 2019: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2018: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2017: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
Keywordsフーリエ級数 / 調和解析学 / 解析的整数論
Outline of Final Research Achievements

The convergence problem of Fourier series has been largely solved by research up to the 1960s in the case of single-variable functions, but in the case of multivariable functions, there are still many things that are not yet understood. In recent years, in addition to the Gibbs phenomenon, the Pinsky phenomenon and the Kuratsubo phenomenon have been discovered, and the complexity of the multivariable Fourier series has become more apparent.
On the other hand, the Gauss circle problem is a problem to evaluate the error between the area of a circle and the number of lattice points in the circle. Gauss proved that the order of error is less than or equal to the power of 1/2 of the area of the circle. In 1915, Hardy conjectured that it would be as close as possible to the power of 1/4, but it remains unresolved today.
In this study, we have proven the equivalence of these two seemingly unrelated unresolved problems.

Academic Significance and Societal Importance of the Research Achievements

フーリエが熱伝導方程式を解いてから約200 年になる。ただし、フーリエの方法には不完全な部分があり、当時から問題点が指摘されていた。その問題点の中心的なもののひとつがフーリエ級数の収束問題である。一方、ガウスの円問題に関するHardy予想は100年来の未解決問題である。
本研究では、これら調和解析学の古典的問題と解析的整数論の難問という、一見無関係と思われる2つの未解決問題の密接な相互関係を明らかにした。このことは、単に大問題の解決に寄与するだけではなく、2つの分野相互に新しい研究手法をもたらす。

Report

(6 results)
  • 2021 Annual Research Report   Final Research Report ( PDF )
  • 2020 Research-status Report
  • 2019 Research-status Report
  • 2018 Research-status Report
  • 2017 Research-status Report
  • Research Products

    (12 results)

All 2022 2021 2020 2019 2017 Other

All Int'l Joint Research (1 results) Journal Article (3 results) (of which Peer Reviewed: 3 results,  Open Access: 3 results) Presentation (4 results) (of which Int'l Joint Research: 3 results,  Invited: 1 results) Remarks (4 results)

  • [Int'l Joint Research] Bandung Institute of Technology/Jenderal Soedirman University(インドネシア)

    • Related Report
      2017 Research-status Report
  • [Journal Article] Multiple Fourier series and lattice point problems2022

    • Author(s)
      Kuratsubo Shigehiko、Nakai Eiichi
    • Journal Title

      Journal of Functional Analysis

      Volume: 282 Issue: 1 Pages: 109272-109272

    • DOI

      10.1016/j.jfa.2021.109272

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] KURATSUBO PHENOMENON OF THE FOURIER SERIES OF SOME RADIAL FUNCTIONS IN FOUR DIMENSIONS2021

    • Author(s)
      Ootsubo Kazuya、Fujima Shoichi、Kuratsubo Shigehiko、Nakai Eiichi
    • Journal Title

      Scientiae Mathematicae Japonicae

      Volume: 84 Issue: 3 Pages: 181-192

    • DOI

      10.32219/isms.84.3_181

    • ISSN
      1346-0447
    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Kuratsubo phenomenon of the Fourier series of some radial functions in four dimensions2020

    • Author(s)
      Kazuya Ootsubo、Shoichi Fujima、Shigehiko Kuratsubo and Eiichi Nakai
    • Journal Title

      Scientiae Mathematicae Japonicae Online

      Volume: 2020

    • Related Report
      2020 Research-status Report
    • Peer Reviewed / Open Access
  • [Presentation] Multiple Fourier series and lattice point problems2019

    • Author(s)
      Eiichi Nakai
    • Organizer
      The 7th East Asian Conference in Harmonic Analysis and Applications
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research
  • [Presentation] A relation of multiple Fourier series and Gauss's circle problems2019

    • Author(s)
      Eiichi Nakai
    • Organizer
      International Conference on Function Spaces and Geometric Analysis and Their Applications
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] 多変数フーリエ級数とガウスの円問題2019

    • Author(s)
      倉坪茂彦, 中井英一
    • Organizer
      日本数学会年会
    • Related Report
      2018 Research-status Report
  • [Presentation] On Kuratsubo phenomenon2017

    • Author(s)
      Kazuya Ootsubo
    • Organizer
      Harmonic Analysis and its Applications in Tokyo 2017
    • Related Report
      2017 Research-status Report
    • Int'l Joint Research
  • [Remarks] 研究業績一覧 List of Publications

    • URL

      http://enakai.sci.ibaraki.ac.jp/publication.html

    • Related Report
      2021 Annual Research Report
  • [Remarks] 研究業績一覧 講演リスト List of Talks

    • URL

      http://enakai.sci.ibaraki.ac.jp/publication-talks.html

    • Related Report
      2021 Annual Research Report
  • [Remarks] 研究業績一覧 ( 中井英一 )

    • URL

      http://enakai.sci.ibaraki.ac.jp/publication-j.html

    • Related Report
      2020 Research-status Report 2019 Research-status Report 2018 Research-status Report
  • [Remarks] http://enakai.sci.ibaraki.ac.jp/publication-j.html

    • Related Report
      2017 Research-status Report

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Published: 2017-07-21   Modified: 2023-01-30  

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