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Noncommutative association schemes, coherent algebras, their irreducible decompositions and applications

Research Project

Project/Area Number 20K03527
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 University

Principal Investigator

Akihiro Munemasa  東北大学, 情報科学研究科, 教授 (50219862)

Co-Investigator(Kenkyū-buntansha) 須田 庄  防衛大学校(総合教育学群、人文社会科学群、応用科学群、電気情報学群及びシステム工学群), 総合教育学群, 准教授 (30710206)
野崎 寛  愛知教育大学, 教育学部, 准教授 (80632778)
生田 卓也  神戸学院大学, 法学部, 教授 (70271111)
Project Period (FY) 2020-04-01 – 2023-03-31
Project Status Completed (Fiscal Year 2022)
Budget Amount *help
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2022: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2021: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2020: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Keywords有限群 / アソシエーション・スキーム / 指標表 / 固有値 / グラフ / アダマール行列 / 組合せデザイン / 代数的組合せ論 / 置換群 / 既約表現
Outline of Research at the Start

組合せ論において重要な概念であるコヒアラント配置の具体例及びその存在可能性について、そのコヒアラント代数の構造定数から自然な基底を決定し、隣接行列との間の変換行列を具体的に計算する。具体例としては三重正則な階数3のアソシエーション・スキーム、擬対称デザインの点とブロック、リンクされた対称デザインの点とブロックなどが挙げられる。これらはパラメータと呼ばれる不定元を用いて代数の構造定数が記述されるので、その不定元を変数とする有理関数体を係数体としてコヒアラント代数を構成する。そのデータを用いてクライン条件や半正定値計画法などに適用し、これまで見えていなかった条件を導出する。

Outline of Final Research Achievements

We applied the algebraic theory of association schemes to combinatorial or geometrical problems, such as the existence of complex Hadamard matrices, classification of distance sets in Euclidean spaces. We also established a characterization of certain combinatorial designs in terms of the natural inequality derived from the irreducible decomposition of a coherent algebra.

Academic Significance and Societal Importance of the Research Achievements

組合せ論的対象の存在問題と分類問題,特にアソシエーション・スキームの理論は,計算機科学においても重要な意味を持ち,代数的手法が有用であることは認知されてきている。特に,非可換アソシエーション・スキームの理論を応用上重要な面を優先的に整備することは学術的意義がある。

Report

(4 results)
  • 2022 Annual Research Report   Final Research Report ( PDF )
  • 2021 Research-status Report
  • 2020 Research-status Report
  • Research Products

    (32 results)

All 2023 2022 2021 2020

All Journal Article (12 results) (of which Int'l Joint Research: 6 results,  Peer Reviewed: 11 results,  Open Access: 5 results) Presentation (19 results) (of which Int'l Joint Research: 11 results,  Invited: 13 results) Book (1 results)

  • [Journal Article] Maximal digraphs whose Hermitian spectral radius is at most 22023

    • Author(s)
      Gavrilyuk Alexander L.、Munemasa Akihiro
    • Journal Title

      Linear Algebra and its Applications

      Volume: 658 Pages: 331-349

    • DOI

      10.1016/j.laa.2022.11.007

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Bounds for sets with few distances distinct modulo a prime ideal2023

    • Author(s)
      野崎寛
    • Journal Title

      第38回代数的組合せ論シンポジウム

      Volume: 38 Pages: 1-7

    • Related Report
      2022 Annual Research Report
  • [Journal Article] Quasi-symmetric 2-(41,9,9) designs and doubly even self-dual codes of length 402022

    • Author(s)
      Munemasa Akihiro、Tonchev Vladimir D.
    • Journal Title

      Applicable Algebra in Engineering, Communication and Computing

      Volume: 33 Issue: 6 Pages: 855-866

    • DOI

      10.1007/s00200-022-00543-w

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] On the spectrum and linear programming bound for hypergraphs2022

    • Author(s)
      Sebastian M. Cioaba, Jack H. Koolen, Masato Mimura, Hiroshi Nozaki, and Takayuki Okuda
    • Journal Title

      European Journal of Combinatorics

      Volume: 104 Pages: 103535-103535

    • DOI

      10.1016/j.ejc.2022.103535

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Rationality of the inner products of spherical s-distance t-designs for t≧2s-2, s≧32022

    • Author(s)
      Boyvalenkov Peter、Nozaki Hiroshi、Safaei Navid
    • Journal Title

      Linear Algebra and its Applications

      Volume: 646 Pages: 107-118

    • DOI

      10.1016/j.laa.2022.03.028

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Q-polynomial coherent configurations2022

    • Author(s)
      Suda Sho
    • Journal Title

      Linear Algebra and its Applications

      Volume: 643 Pages: 166-195

    • DOI

      10.1016/j.laa.2022.02.009

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Journal Article] A Proof of a Dodecahedron Conjecture for Distance Sets2021

    • Author(s)
      Nozaki Hiroshi、Shinohara Masashi
    • Journal Title

      Graphs and Combinatorics

      Volume: 37 Issue: 5 Pages: 1585-1603

    • DOI

      10.1007/s00373-021-02318-5

    • Related Report
      2021 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Signed analogue of line graphs and their smallest eigenvalues2021

    • Author(s)
      Gavrilyuk Alexander L.、Munemasa Akihiro、Sano Yoshio、Taniguchi Tetsuji
    • Journal Title

      Journal of Graph Theory

      Volume: 98 Issue: 2 Pages: 309-325

    • DOI

      10.1002/jgt.22699

    • Related Report
      2021 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] A note on Assmus-Mattson type theorems2021

    • Author(s)
      Tsuyoshi Miezaki, Akihiro Munemasa & Hiroyuki Nakasora
    • Journal Title

      Designs, Codes and Cryptography

      Volume: 89 Issue: 5 Pages: 843-858

    • DOI

      10.1007/s10623-021-00848-w

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Journal Article] Maximality of Seidel matrices and switching roots of graphs2021

    • Author(s)
      Cao Meng-Yue、Koolen Jack H.、Munemasa Akihiro、Yoshino Kiyoto
    • Journal Title

      Graphs and Combinatorics

      Volume: 37 Issue: 5 Pages: 1491-1507

    • DOI

      10.1007/s00373-021-02359-w

    • Related Report
      2021 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Bordered Complex Hadamard Matrices and Strongly Regular Graphs2021

    • Author(s)
      Takuya Ikuta and Akihiro Munemasa
    • Journal Title

      Interdisciplinary Information Sciences

      Volume: 27 Issue: 1 Pages: 41-56

    • DOI

      10.4036/iis.2020.R.03

    • NAID

      130008009393

    • ISSN
      1340-9050, 1347-6157
    • Related Report
      2021 Research-status Report 2020 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Maximal 2-distance sets containing the regular simplex2020

    • Author(s)
      Hiroshi Nozaki, Masashi Shinohara
    • Journal Title

      Discrete Mathematics

      Volume: 343 Issue: 11 Pages: 112071-112071

    • DOI

      10.1016/j.disc.2020.112071

    • Related Report
      2020 Research-status Report
    • Peer Reviewed / Open Access
  • [Presentation] On the shadows of the unimodular lattices constructed from ternary self-dual codes2023

    • Author(s)
      Akihiro Munemasa
    • Organizer
      直交デザインと関連する組合せ論
    • Related Report
      2022 Annual Research Report
  • [Presentation] Weakly distance-regular circulants2023

    • Author(s)
      Akihiro Munemasa
    • Organizer
      The 8th Workshop on Algebraic Graph Theory and its Applications
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Extended double covers of non-symmetric association schemes of class 22023

    • Author(s)
      Takuya Ikuta
    • Organizer
      直交デザインと関連する組合せ論
    • Related Report
      2022 Annual Research Report
  • [Presentation] Quasi-symmetric 2-(41,9,9) designs and doubly even self-dual codes of length 402022

    • Author(s)
      Akihiro Munemasa
    • Organizer
      Hadamard 2020+2
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Quasi-symmetric 2-(41, 9, 9) designs2022

    • Author(s)
      Akihiro Munemasa
    • Organizer
      第38回代数的組合せ論シンポジウム
    • Related Report
      2022 Annual Research Report
  • [Presentation] Association schemes and spin models2022

    • Author(s)
      Akihiro Munemasa
    • Organizer
      Graph Theory, Algebraic Combinatorics and Mathematical Physics
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Sphere packings, root systems and signed graphs2022

    • Author(s)
      Akihiro Munemasa
    • Organizer
      Combinatorics Today
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Bounds for sets with few distances distinct modulo a prime ideal2022

    • Author(s)
      野崎寛
    • Organizer
      第38回代数的組合せ論シンポジウム
    • Related Report
      2022 Annual Research Report
    • Invited
  • [Presentation] 整数環の素イデアルを用いたs-距離集合の上界の改善2022

    • Author(s)
      野崎寛
    • Organizer
      愛媛大学代数セミナー
    • Related Report
      2022 Annual Research Report
  • [Presentation] Semibiplanes and an inequality for incidence structures2022

    • Author(s)
      宗政昭弘
    • Organizer
      Workshop on Algebraic Combinatorics, Online (zoom) organized by National Taiwan University
    • Related Report
      2021 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Extended double covers of non-symmetric association schemes of class 22022

    • Author(s)
      宗政昭弘
    • Organizer
      The 6th Workshop on Algebraic Graph Theory and its Applications
    • Related Report
      2021 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] A generalization of mod-p bounds for s-distance sets to a ring of integers2022

    • Author(s)
      野崎寛
    • Organizer
      Workshop on Algebraic Combinatorics, Online (zoom) organized by National Taiwan University
    • Related Report
      2021 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Hermitian adjacency matrices of digraphs and root lattices over the Gaussian integers2021

    • Author(s)
      宗政昭弘
    • Organizer
      Algebraic Graph Theory and Quantum Information
    • Related Report
      2021 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Few-distance sets and the Dodecahedron conjecture2021

    • Author(s)
      野崎寛
    • Organizer
      Extremal problems of discrete geometry Online (zoom) organized by Moscow Institute of Physics and Technology
    • Related Report
      2021 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Linear programming bounds on the order of a regular graph given eigenvalues or girth -regular graphs with large girth-2021

    • Author(s)
      野崎寛
    • Organizer
      A number theoretic approach for Post-Quantum Cryptography related to Ramanujan graphs, Online (zoom) organized by Kyushu University
    • Related Report
      2021 Research-status Report
    • Invited
  • [Presentation] Note on s-distance sets in the pseudo Euclidean space R^{p,q}2021

    • Author(s)
      野崎寛
    • Organizer
      名古屋組合せ論セミナー, Online (zoom), 愛知県立大学
    • Related Report
      2021 Research-status Report
  • [Presentation] Neighbor-balanced bijections of hypercubes2021

    • Author(s)
      宗政昭弘
    • Organizer
      The 4-th Workshop on Algebraic Graph Theory
    • Related Report
      2020 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] The regular two-graph on 276 vertices revisited2020

    • Author(s)
      宗政昭弘
    • Organizer
      離散数学とその応用研究集会2020
    • Related Report
      2020 Research-status Report
  • [Presentation] The regular two-graph on 276 vertices revisited2020

    • Author(s)
      宗政昭弘
    • Organizer
      The Ural Workshop on Group Theory and Combinatorics
    • Related Report
      2020 Research-status Report
    • Int'l Joint Research / Invited
  • [Book] Algebraic Combinatorics and the Monster Group2023

    • Author(s)
      Takuya Ikuta, Akihiro Munemasa
    • Publisher
      Cambridge University Press
    • ISBN
      9781009338042
    • Related Report
      2022 Annual Research Report

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Published: 2020-04-28   Modified: 2024-12-25  

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