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Study of the geography of fibrations through branched coverings, differencial equations and moduli spaces

Research Project

Project/Area Number 18K03264
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 11010:Algebra-related
Research InstitutionTohoku Gakuin University

Principal Investigator

ISHIDA Hirotaka  東北学院大学, 情報学部, 教授 (30435458)

Project Period (FY) 2018-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2022: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2021: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Keywords代数曲線束 / 代数曲面 / 分岐被覆 / モジュライ空間 / 複素微分方程式
Outline of Final Research Achievements

In this project, we studied the problem of the geography of fibrations of algebraic curves on a non-singular projective algebraic curve with specific structures which is the question of what values of the relative Euler-Poincare characteristic, the self-intersection number of the relative canonical divisor and the genus of a fiber can take. We mainly considered fibrations given by triple coverings of projective line bundles, and proved inequalities among these invariants that depending on the type of branch loci. In particular, we show that the lower bounds on the slope and the Euler-Poincare characteristic differ from each other depending on whether the genus of a fiber is congruent to 2 modulo 3 or not. Furthermore, we specifically gave triple coverings of projective line bundles and proved the existence of fibrations of algebraic curves.

Academic Significance and Societal Importance of the Research Achievements

代数曲線束のジオグラフィーに関する主要な問題の1つである「特定の構造をもつ代数曲線束の不変量がどのような値を取り得るか」に関して,先行研究が豊富とは言えなかった.
本研究課題の成果により, 特にファイバーの種数が3を法として2と合同であるかどうかによって,射影直線束の3重被覆で与えられる代数曲線束の不変量に制約があることが明確になった.他の代数曲線束の構造においても,本成果と同様の現象が予想でき,今後の代数曲線束のジオグラフィーの問題の進展が期待できると考える.

Report

(7 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Research-status Report
  • 2021 Research-status Report
  • 2020 Research-status Report
  • 2019 Research-status Report
  • 2018 Research-status Report
  • Research Products

    (6 results)

All 2019 2018 Other

All Presentation (4 results) (of which Invited: 4 results) Remarks (2 results)

  • [Presentation] On certain triple coverings of projective line bundles2019

    • Author(s)
      石田弘隆
    • Organizer
      Algebraic surfaces and related topics
    • Related Report
      2019 Research-status Report
    • Invited
  • [Presentation] ある射影直線束の 3 重被覆で与えられる代数曲線束のスロープに関して2019

    • Author(s)
      石田弘隆
    • Organizer
      第17回代数曲線論シンポジウム
    • Related Report
      2019 Research-status Report
    • Invited
  • [Presentation] 射影直線束の巡回3重被覆の構造をもつ代数曲線束の地誌学2019

    • Author(s)
      石田弘隆
    • Organizer
      農工大数学セミナー2019
    • Related Report
      2018 Research-status Report
    • Invited
  • [Presentation] 射影直線束のガロア被覆の構造をもつ一般型曲面について2018

    • Author(s)
      石田弘隆
    • Organizer
      射影多様体の幾何とその周辺2018
    • Related Report
      2018 Research-status Report
    • Invited
  • [Remarks] 第7回 代数幾何学研究集会-宇部-

    • URL

      http://www2.ube-k.ac.jp/kmiura/ube2020.pdf

    • Related Report
      2019 Research-status Report
  • [Remarks] 第6回 代数幾何学研究集会-宇部-

    • URL

      http://www2.ube-k.ac.jp/kmiura/ube2019.pdf

    • Related Report
      2018 Research-status Report

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Published: 2018-04-23   Modified: 2025-01-30  

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