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Study of homotopy theory which relates to combinatorics

Research Project

Project/Area Number 19K14536
Research Category

Grant-in-Aid for Early-Career Scientists

Allocation TypeMulti-year Fund
Review Section Basic Section 11020:Geometry-related
Research InstitutionShinshu University (2023)
University of the Ryukyus (2019-2022)

Principal Investigator

Matsushita Takahiro  信州大学, 学術研究院理学系, 准教授 (30812292)

Project Period (FY) 2019-04-01 – 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: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2021: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2019: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Keywords近傍複体 / 独立複体 / 相対的幽霊写像 / 彩色数 / 単体複体 / 埋め込み / 支配複体 / 彩色埋め込み定理 / 彩色問題 / Hedetniemi 予想 / Z/2-指数 / 幽霊写像 / 箱複体
Outline of Research at the Start

グラフ理論において長年未解決の問題として, Hedetniemi 予想というものがある.近年の研究によって, Hedetniemi 予想からトポロジーの問題が得られることがわかったが,そのトポロジーの問題を反証することで, Hedetniemi 予想が反証されることになる.このように,グラフ理論などの組合せ論的な問題から,トポロジーの問題を構成し,そのトポロジーの問題について取り組む.

Outline of Final Research Achievements

In this study, we study topological combinatorics in the context of applications of homotopy theory to the Hedetniemi conjecture, which had been an unsolved problem in graph theory, and of relative phantom maps, which are a generalization of phantom maps from the viewpoint of Z/2-indices. Although I had to change our research plan due to the negative resolution of the Hedetniemi conjecture by Shitov, I was able to obtain many results on topological combinatorics as a result. In particular, the generalization of the van Kampen-Flores theorem on triangulations of manifolds, determination of homotopy types of independence complexes of certain grid graphs, and research on dominance and neighborhood complexes of graphs have attracted international attention.

Academic Significance and Societal Importance of the Research Achievements

本研究は数学の一分野であるホモトピー論と位相的組合せ論に新たな視点をもたらし、特に多様体の三角形分割に対する van Kampen-Flores の定理の研究やグラフの独立複体や支配複体の研究などにより、グラフ理論の応用において顕著な進展を達成した。グラフの彩色問題への新しいアプローチは、数学の基本問題に対する理解を深める上で重要な役割を果たしている。彩色問題を含め、グラフ理論における多くの研究は、計算機科学やネットワーク設計など、他分野への応用可能性の大きい分野であり、純粋数学の範囲を超えた社会的影響を期待させる。このように、本研究は学術的にも社会的にも大きな意義を持っている。

Report

(6 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
  • Research Products

    (37 results)

All 2024 2023 2022 2021 2020 2019

All Journal Article (15 results) (of which Peer Reviewed: 15 results) Presentation (22 results) (of which Int'l Joint Research: 5 results,  Invited: 22 results)

  • [Journal Article] Independence complexes of (n x 6)-grid graphs2024

    • Author(s)
      Matsushita Takahiro、Wakatsuki Shun
    • Journal Title

      Homology, Homotopy and Applications

      Volume: 26 Issue: 1 Pages: 15-27

    • DOI

      10.4310/hha.2024.v26.n1.a2

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Mixed commutator lengths, wreath products and general ranks2023

    • Author(s)
      Kawasaki Morimichi、Kimura Mitsuaki、Maruyama Shuhei、Matsushita Takahiro、Mimura Masato
    • Journal Title

      Kodai Mathematical Journal

      Volume: 46 Issue: 2 Pages: 145-183

    • DOI

      10.2996/kmj46202

    • ISSN
      0386-5991, 1881-5472
    • Year and Date
      2023-06-30
    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Journal Article] van Kampen-Flores Theorem for Cell Complexes2023

    • Author(s)
      Kishimoto Daisuke、Matsushita Takahiro
    • Journal Title

      Discrete & Computational Geometry

      Volume: 71 Issue: 3 Pages: 1081-1091

    • DOI

      10.1007/s00454-023-00559-0

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Independence complexes of (n × 4) and (n × 5)-grid graphs2023

    • Author(s)
      Matsushita Takahiro、Wakatsuki Shun
    • Journal Title

      Topology and its Applications

      Volume: 334 Pages: 108541-108541

    • DOI

      10.1016/j.topol.2023.108541

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Commuting symplectomorphisms on a surface and the flux homomorphism2023

    • Author(s)
      Kawasaki Morimichi、Kimura Mitsuaki、Matsushita Takahiro、Mimura Masato
    • Journal Title

      Geometric and Functional Analysis

      Volume: 33 Issue: 5 Pages: 1322-1353

    • DOI

      10.1007/s00039-023-00644-9

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Bavard's duality theorem for mixed commutator length2022

    • Author(s)
      Morimichi Kawasaki, Mitsuaki Kimura, Takahiro Matsushita, and Masato Mimura
    • Journal Title

      L’Enseignement Mathematique

      Volume: 68 Issue: 3 Pages: 441-481

    • DOI

      10.4171/lem/1037

    • Related Report
      2022 Research-status Report
    • Peer Reviewed
  • [Journal Article] Dominance complexes and vertex cover numbers of graphs2022

    • Author(s)
      Matsushita Takahiro
    • Journal Title

      Journal of Applied and Computational Topology

      Volume: - Issue: 2 Pages: 363-368

    • DOI

      10.1007/s41468-022-00109-2

    • Related Report
      2022 Research-status Report
    • Peer Reviewed
  • [Journal Article] Jacobi identity in polyhedral products2022

    • Author(s)
      Kishimoto Daisuke、Matsushita Takahiro、Yoshise Ryusei
    • Journal Title

      Topology and its Applications

      Volume: 312 Pages: 108079-108079

    • DOI

      10.1016/j.topol.2022.108079

    • Related Report
      2022 Research-status Report
    • Peer Reviewed
  • [Journal Article] Matching complexes of polygonal line tilings2022

    • Author(s)
      MATSUSHITA Takahiro
    • Journal Title

      Hokkaido Mathematical Journal

      Volume: 51 Issue: 3

    • DOI

      10.14492/hokmj/2019-213

    • Related Report
      2022 Research-status Report
    • Peer Reviewed
  • [Journal Article] Neighborhood complexes of Kronecker double coverings2021

    • Author(s)
      Takahiro Matsushita
    • Journal Title

      Osaka Journal of Mathematics

      Volume: 58 Pages: 637-645

    • NAID

      120007140319

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Journal Article] Relative phantom maps and rational homotopy2021

    • Author(s)
      Daisuke Kishimoto, Takahiro Matsushita
    • Journal Title

      Proceedings of the American Mathematical Society

      Volume: 149 Pages: 4029-4040

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Journal Article] Graphs whose Kronecker covers are bipartite Kneser graphs2021

    • Author(s)
      Takahiro Matsushita
    • Journal Title

      Discrete Mathematics

      Volume: 344

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Journal Article] Relative phantom maps2019

    • Author(s)
      Kouyemon Iriye, Daisuke Kishimoto, Takahiro Matsushita
    • Journal Title

      Algebraic & Geometric Topology

      Volume: 19 Pages: 341-362

    • Related Report
      2019 Research-status Report
    • Peer Reviewed
  • [Journal Article] Matching complexes of small grids2019

    • Author(s)
      Takahiro Matsushita
    • Journal Title

      The Electronic Journal of Combinatorics

      Volume: 26 Pages: 1-8

    • Related Report
      2019 Research-status Report
    • Peer Reviewed
  • [Journal Article] Z2-indiced and Hedetniemi's conjecture2019

    • Author(s)
      Takahiro Matsushita
    • Journal Title

      Discrete & Computational Geometry

      Volume: 62 Pages: 662-673

    • Related Report
      2019 Research-status Report
    • Peer Reviewed
  • [Presentation] Van Kampen-Flores theorem and Stiefel-Whitney classes2023

    • Author(s)
      Takahiro Matsushita
    • Organizer
      金曜トポロジーセミナー(九州大学)
    • Related Report
      2023 Annual Research Report
    • Invited
  • [Presentation] Van Kampen-Flores theorem and Stiefel-Whitney classes2023

    • Author(s)
      Takahiro Matsushita
    • Organizer
      ホモトピー論シンポジウム2023
    • Related Report
      2023 Annual Research Report
    • Invited
  • [Presentation] Van Kampen-Flores theorem and Stiefel-Whitney classes2023

    • Author(s)
      Takahiro Matsushita
    • Organizer
      第49回変換群論シンポジウム
    • Related Report
      2023 Annual Research Report
    • Invited
  • [Presentation] ファンカンペン=フローレスの定理とシュティーフェル=ホイットニー類2023

    • Author(s)
      Takahiro Matsushita
    • Organizer
      談話会(信州大学)
    • Related Report
      2023 Annual Research Report
    • Invited
  • [Presentation] 位相的 Radon の定理と van Kampen-Flores の定理2023

    • Author(s)
      Takahiro Matsushita
    • Organizer
      大阪組合せ論セミナー
    • Related Report
      2023 Annual Research Report
    • Invited
  • [Presentation] Independence complexes of certain square grid graphs2023

    • Author(s)
      Takahiro Matsushita
    • Organizer
      Joint Mathematics Meeting 2023
    • Related Report
      2022 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] The spaces of non-extendable quasimorphisms2022

    • Author(s)
      松下尚弘
    • Organizer
      Classifying spaces in homotopy theory: in honour of Ran Levi's 60th Birthday.
    • Related Report
      2022 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] 混合交換子長の幾何学的解釈2022

    • Author(s)
      松下尚弘
    • Organizer
      The 6th Workshop on Geometric Group Theory
    • Related Report
      2022 Research-status Report
    • Invited
  • [Presentation] 安定混合交換子長の非同値性について2022

    • Author(s)
      松下尚弘
    • Organizer
      ホモトピー論シンポジウム2022
    • Related Report
      2022 Research-status Report
    • Invited
  • [Presentation] 不変擬準同型と混合交換子長について2022

    • Author(s)
      松下尚弘
    • Organizer
      日本数学会2022年度年会 トポロジー分科会特別講演
    • Related Report
      2021 Research-status Report
    • Invited
  • [Presentation] 拡張不能な擬準同型のなす空間について2021

    • Author(s)
      松下尚弘
    • Organizer
      N-KOOK セミナー
    • Related Report
      2021 Research-status Report
    • Invited
  • [Presentation] 拡張不能な擬準同型について2021

    • Author(s)
      松下尚弘
    • Organizer
      談話会(京都大学数学教室)
    • Related Report
      2021 Research-status Report
    • Invited
  • [Presentation] Graphs whose Kronecker covers are bipartite Kneser graphs2021

    • Author(s)
      Takahiro Matsushita
    • Organizer
      トポロジー火曜セミナー
    • Related Report
      2021 Research-status Report
    • Invited
  • [Presentation] 群の擬準同型の拡張問題と商群の二次コホモロジーについて2021

    • Author(s)
      松下尚弘
    • Organizer
      2021年度ホモトピー論シンポジウム
    • Related Report
      2021 Research-status Report
    • Invited
  • [Presentation] A geometric interpretation of mixed commutator lengths2020

    • Author(s)
      Takahiro Matsushita
    • Organizer
      Homotopy theory symposium 2020
    • Related Report
      2020 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] 独立複体と関連する単体複体について(I, II)2020

    • Author(s)
      松下尚弘
    • Organizer
      空間の代数的・幾何的モデルとその周辺
    • Related Report
      2020 Research-status Report
    • Invited
  • [Presentation] 相対的幽霊写像2020

    • Author(s)
      松下尚弘
    • Organizer
      東北大学談話会
    • Related Report
      2020 Research-status Report
    • Invited
  • [Presentation] Bounded degree complexes and independence complexes of hypergraphs2020

    • Author(s)
      松下尚弘
    • Organizer
      代数トポロジーセミナー
    • Related Report
      2019 Research-status Report
    • Invited
  • [Presentation] 小さなグリッドグラフのマッチング複体のホモトピー型について2019

    • Author(s)
      松下尚弘
    • Organizer
      トポロジー金曜セミナー
    • Related Report
      2019 Research-status Report
    • Invited
  • [Presentation] Relative phantom maps and rational homotopy2019

    • Author(s)
      Takahiro Matsushita
    • Organizer
      The Homotopy Symposium
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Relative phantom maps2019

    • Author(s)
      Takahiro Matsushita
    • Organizer
      The Third Pan-Pacific International Conference on Topology and Applications
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Matching complexes of small grids2019

    • Author(s)
      松下尚弘
    • Organizer
      微分空間・トポロジーと組み合わせ構造
    • Related Report
      2019 Research-status Report
    • Invited

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Published: 2019-04-18   Modified: 2025-01-30  

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