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Simply Connected Distance-Regular Graphs

Research Project

Project/Area Number 18K03222
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 11010:Algebra-related
Research InstitutionInternational Christian University

Principal Investigator

Suzuki Hiroshi  国際基督教大学, 教養学部, 名誉教授 (10135767)

Project Period (FY) 2018-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2022: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2021: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2020: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2018: ¥260,000 (Direct Cost: ¥200,000、Indirect Cost: ¥60,000)
Keywords距離正則グラフ / グラフの基本群 / グラフの普遍被覆 / 代数的組み合わせ論 / 弱距離正則有効グラフ / Terwilliger 代数 / 代数的組合せ論 / 代数的グラフ理論
Outline of Final Research Achievements

We have tried to characterize Classical DRGs by assuming that Γ satisfies π(Γ, x, 6) = π(Γ, x) in distance regular graphs (DRGs) using geometric or graph-theoretic methods, but have not succeeded to date.
On the other hand, we have made progress in the theory of representations of weakly distance-regular digraphs and their structures, which can provide more precise information, as well as in methods using Terwilliger algebras corresponding to representation algebras. We have presented a part of the result at a seminar already and we are under the process of their publications.
The relationship between algebraic and geometric theories of covering is still awaiting clarification.

Academic Significance and Societal Importance of the Research Achievements

代数的組合せ論は、組み合わせ構造を、代数的手法によって、研究するものであるが、同時に、組み合わせ的、幾何的手法と、代数的手法の関連を明らかにすることも含む。一つの問題を多様な視点から見ることは、一般的に重要であるが、そこにとどまらず、それらの手法の関連を明らかにすることは、問題を俯瞰的に見る視点を与えるためにも、重要であると思われる。本研究は、具体的な代数的組合せ論の課題のみを扱っているが、そのような研究の精神は、他にも応用ができると願っている。

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 2017 Other

All Int'l Joint Research (2 results) Journal Article (2 results) (of which Peer Reviewed: 2 results) Presentation (1 results) (of which Int'l Joint Research: 1 results) Remarks (1 results)

  • [Int'l Joint Research] University of Wisconsin, Madison(米国)

    • Related Report
      2023 Annual Research Report
  • [Int'l Joint Research] Beijing Normal University(中国)

    • Related Report
      2023 Annual Research Report
  • [Journal Article] Coverings and homotopy of a graph2018

    • Author(s)
      Suzuki Hiroshi
    • Journal Title

      Discrete Mathematics

      Volume: 341 Issue: 7 Pages: 1994-2010

    • DOI

      10.1016/j.disc.2018.03.028

    • Related Report
      2018 Research-status Report
    • Peer Reviewed
  • [Journal Article] Distance-Regular Graphs of Large Diameter That Are Completely Regular Clique Graphs2017

    • Author(s)
      Hiroshi Suzuki
    • Journal Title

      J. Algebraic Combin.

      Volume: - Issue: 3 Pages: 369-404

    • DOI

      10.1007/s10801-017-0808-9

    • Related Report
      2018 Research-status Report
    • Peer Reviewed
  • [Presentation] The universal C-cover of a completely regular clique graph2019

    • Author(s)
      Hiroshi Suzuki
    • Organizer
      The 9th Slovenian International Conference on Graph Theory - Bled’19
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research
  • [Remarks] Lecture Note on Terwilliger Algebra

    • URL

      https://icu-hsuzuki.github.io/t-algebra/

    • Related Report
      2023 Annual Research Report 2022 Research-status Report

URL: 

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

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