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Geometry of Planar 3-webs

Research Project

Project/Area Number 15K04838
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Research Field Geometry
Research InstitutionOchanomizu University

Principal Investigator

Nakai Isao  お茶の水女子大学, 基幹研究院, 教授 (90207704)

Project Period (FY) 2015-04-01 – 2019-03-31
Project Status Completed (Fiscal Year 2018)
Budget Amount *help
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2015: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
KeywordsWEB 幾何学 / 曲率形式 / 位相剛性 / WEB幾何学 / 曲率 / 剛性 / 常微分方程式 / 葉層 / PLANAR WEB / CURVATURE / ODE / RESONANCE / web / curvature / resonance / singularity
Outline of Final Research Achievements

A simple elementary method of computation of the curvature form of singular planar 3-webs has been established. A planar web is a configuration of excessively many, more than or equal to 3, foliations of the plane, one parameter families of curves filling up the plane. This structure is seen ubiquitously in nature, for instance in configurations of waves. The canonical model for this structure is represented by 3 families of parallel lines, which is called a hexagonal 3-web. In general almost all webs differ topologically from this canonical model. The difference is measured by quantified by the so-called web curvature form. The curvature form was given by Blaschke et al. in 1930's for nonsingular webs. By this research project, the curvature was computed for arbitrarily singular webs.

Academic Significance and Societal Importance of the Research Achievements

Web 構造は波の重ね合わせの構造である。このような構造は自然界だけでなく、数理的考察の場面でいたるところに現れる。本研究課題の3-web の曲率形式は,WEB幾何学の研究の基礎をなしている。特異3-web に対するその計算方法の確立は、今後の一般のWEB 構造の研究への応用が期待でき、自然科学への将来の応用が期待できる。

Report

(5 results)
  • 2018 Annual Research Report   Final Research Report ( PDF )
  • 2017 Research-status Report
  • 2016 Research-status Report
  • 2015 Research-status Report
  • Research Products

    (5 results)

All 2018 2016 2015 Other

All Int'l Joint Research (1 results) Journal Article (2 results) (of which Open Access: 2 results,  Peer Reviewed: 1 results) Presentation (2 results) (of which Int'l Joint Research: 1 results,  Invited: 2 results)

  • [Int'l Joint Research] Institut de Mathematiques de Bordeaux/Universite de Bordeaux I(フランス)

    • Related Report
      2018 Annual Research Report
  • [Journal Article] Web geometry of solutions of first order ODEs2018

    • Author(s)
      Isao Nakai
    • Journal Title

      Natural Science Report, Ochanomizu University

      Volume: 68 Pages: 1-5

    • NAID

      40021527760

    • Related Report
      2018 Annual Research Report
    • Open Access
  • [Journal Article] Finding roots by a simple origami2016

    • Author(s)
      ISAO NAKAI
    • Journal Title

      Ochanomizu University Natural Science Report

      Volume: 66,no.1 Pages: 1-17

    • NAID

      120005860185

    • Related Report
      2015 Research-status Report
    • Peer Reviewed / Open Access
  • [Presentation] Web geometriy from the view point of rigidity and curvature2018

    • Author(s)
      Isao Nakai
    • Organizer
      Seminaire de Geometrie, IMB, Universite de Bordeaux I
    • Related Report
      2018 Annual Research Report
    • Invited
  • [Presentation] Some topics in web geometry2015

    • Author(s)
      Isao Nakai
    • Organizer
      日本数学会秋季会
    • Place of Presentation
      京都産業大学
    • Year and Date
      2015-09-15
    • Related Report
      2015 Research-status Report
    • Int'l Joint Research / Invited

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Published: 2015-04-16   Modified: 2020-03-30  

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