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2015 Fiscal Year Annual Research Report

双有理幾何:クレモナ群の部分群とそれらの生成元

Research Project

Project/Area Number 15F15751
Research InstitutionKyoto University

Principal Investigator

向井 茂  京都大学, 数理解析研究所, 教授 (80115641)

Co-Investigator(Kenkyū-buntansha) HEDEN ISAC  京都大学, 数理解析研究所, 外国人特別研究員
Project Period (FY) 2015-10-09 – 2018-03-31
Keywords代数学
Outline of Annual Research Achievements

Heden has been studying the decomposition group of a line L in the projective plane, i.e. the subgroup of birational transformations of the plane that send L to itself birationally. This is a joint work with S. Zimmermann (Basel University), and they have been able to prove that this group is generated by its elements of degree 1 and one element of degree 2 and also that it does not decompose as a non-trivial amalgamated product. These results were submitted to a mathematical journal for publication in January and after receiving a positive report, we are now working on minor revisions. We have also started to write down some generalizations that came out of discussions when he traveled to Switzerland in January to participate in "5th Swiss-French workshop on algebraic geometry" - in particular some similar results about rational plane curves of higher degree.

At the conference “14th affine algebraic geometry meeting” in Osaka, related to his talk, a collaboration with A. Dubouloz (Bourgogne University) and T. Kishimoto (Saitama University) was initiated. Given the spectrum S of a regular 2-dimensional local ring, with closed point o, and a non-trivial principal additive bundle P over S-{o}, they try to classify all affine extensions P’ of P, i.e. affine Ga-threefolds P’ that can be obtained from P by adding a fiber over the point o. They are making progress on the problem.

Current Status of Research Progress
Current Status of Research Progress

1: Research has progressed more than it was originally planned.

Reason

Heden is quite happy with the results obtained so far, they correspond roughly to the plans in his research proposal. The research environment at RIMS is outstanding, the generous research-in-aid grant has allowed me to purchase a computer and to travel to conferences and seminars, and the secretaries have been very helpful with all administration, including practical issues about living in Kyoto, so I have been able to focus fully on research.

Strategy for Future Research Activity

Heden has been organising an informal reading seminar with other postdoctoral fellows at RIMS on Mori theory. They have been reading Matsuki’s book “Introduction to the Mori program”. Heden expects that this will be very useful for him as he plans to use the Sarkisov program in my study of subgroups of Bir(P^3) as described in the second half of my research plan.

  • Research Products

    (2 results)

All 2016 2015

All Presentation (2 results) (of which Int'l Joint Research: 1 results,  Invited: 2 results)

  • [Presentation] Extensions of principal additive bundles over a punctured surface2016

    • Author(s)
      Isac Heden
    • Organizer
      THE 14TH AFFINE ALGEBRAIC GEOMETRY MEETING
    • Place of Presentation
      Kwansei Gakuin University, Osaka Umeda Campus, (大阪府大阪市)
    • Year and Date
      2016-03-05 – 2016-03-05
    • Int'l Joint Research / Invited
  • [Presentation] The group of Cremona transformations generated by the standard and linear maps2015

    • Author(s)
      Isac Heden
    • Organizer
      KIAS seminar of algebraic geometry
    • Place of Presentation
      KIAS (Seoul Korea)
    • Year and Date
      2015-12-10 – 2015-12-10
    • Invited

URL: 

Published: 2016-12-27  

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