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On some relations between complex surface singularities of some types and degeneration families of compact Riemann surfaces.

Research Project

Project/Area Number 20540062
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Geometry
Research InstitutionGunma University

Principal Investigator

TOMARU Tadashi  Gunma University, 医学部, 教授 (70132579)

Project Period (FY) 2008 – 2010
Project Status Completed (Fiscal Year 2010)
Budget Amount *help
¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2010: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2009: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2008: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Keywords複素二次元特異点 / リーマン面の退化族 / 複素2次元特異点 / 閉リーマン面の退化 / C*-作用をもつ退化族 / 閉リーマン面 / C*-退化族 / 特異点
Research Abstract

Since 15 years ago, we have been researching some relations between normal surface singularities and degenerations of compact complex smooth curves.
Around ten years ago, I wrote a paper 「Pencil genus for normal surface singularities」(J.Math.Soc.Japan, 2007). There, we prove that given a normal surface singularity (X,0) and an element f of the maximal ideal of the singularity, there exists a one parameter degeneration family of of curves which naturally extends the resolution space and the fiber map extends f. Using this result, we defined an invariant whose name is pencil genus of (X,o), and also studied the several properties.
Now, let C* be the complex multiplicative group. Around 6 years ago, we have been studying the C*-equivariant degenerations family of curves. Also, we call them C*-pencil of curves. In this research, we studied the several relations between C*-pencil of curves and normal surface singularities with C*-action. From this point of view, we can introduced the notion of "dual" C*-pencil of curves. This properties reflect dualities of some invariants (i.e., for example, Milnor numbers and Goto-Watanabe a-invariant). To prove this, we also prove a fundamental formula on cyclic covers of cyclic quotient singularities. Also, we gave a canonical method to construct all C*-pencil of curves from holomorphic line bundle on curves.
We complete a paper whose title is [C*-equivariant degenerations of curves and normal surface singularities with C*-action], which contains 51 pages and was submitted a journal in May 4 in this year.

Report

(4 results)
  • 2010 Annual Research Report   Final Research Report ( PDF )
  • 2009 Annual Research Report
  • 2008 Annual Research Report
  • Research Products

    (6 results)

All 2010 2009

All Journal Article (4 results) (of which Peer Reviewed: 4 results) Presentation (2 results)

  • [Journal Article] Complex surface singularities and degenerations of compact complex curves.2010

    • Author(s)
      Tomaru Tadasi
    • Journal Title

      Demonstratio Mathematica 42(2)

      Pages: 39-59

    • Related Report
      2010 Final Research Report
    • Peer Reviewed
  • [Journal Article] Complex surface singularities and degenerations of compact complex curves2010

    • Author(s)
      Tadashi Tomaru
    • Journal Title

      Demonstratio Mathematica

      Volume: 42(2) Pages: 39-59

    • Related Report
      2010 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Complex surface singularities and degenerations of compact complex curves.2010

    • Author(s)
      Tadashi Tomaru
    • Journal Title

      Demonstratio Math. 43(1)(In Press)

    • Related Report
      2009 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Complex surface singularities and degenerations of compact complex curves2009

    • Author(s)
      Tadashi Tomaru
    • Journal Title

      Demonstratio Math. (In Press)

    • Related Report
      2008 Annual Research Report
    • Peer Reviewed
  • [Presentation] Degenerations of compact complex curves and their cyclic coverings.2010

    • Author(s)
      都丸正
    • Organizer
      Singularities in Aarhus'
    • Place of Presentation
      デンマーク・オーフス市オーフス大学
    • Year and Date
      2010-08-19
    • Related Report
      2010 Final Research Report
  • [Presentation] 講演タイトル:リーマン面のC*作用付きの退化族とC*作用付き二次元特異点について2009

    • Author(s)
      都丸正
    • Organizer
      多変数関数論冬セミナー
    • Place of Presentation
      熊本大学理学部
    • Year and Date
      2009-12-20
    • Related Report
      2010 Final Research Report

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Published: 2008-04-01   Modified: 2016-04-21  

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