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Theory of operator algebras and functional analytic group theory

Research Project

Project/Area Number 20H01806
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Review Section Basic Section 12010:Basic analysis-related
Research InstitutionKyoto University

Principal Investigator

Ozawa Narutaka  京都大学, 数理解析研究所, 教授 (60323466)

Project Period (FY) 2020-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥17,030,000 (Direct Cost: ¥13,100,000、Indirect Cost: ¥3,930,000)
Fiscal Year 2023: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2022: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2021: ¥10,400,000 (Direct Cost: ¥8,000,000、Indirect Cost: ¥2,400,000)
Fiscal Year 2020: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
Keywords解析的群論 / 離散群 / 作用素環論 / 関数解析 / 関数解析的群論 / Kazhdanの性質 / 群論 / ランダムウォーク / 函数解析 / 離散群論 / Banach空間論
Outline of Research at the Start

作用素環論は量子情報理論や場の量子論を始めとする数理物理学,指数定理を介した幾何学,群論,力学系理論,エルゴード理論などと繋がりのある広い分野である.本研究計画では,研究代表個人による研究に合わせて,研究代表が組織委員の幹事を務める京都大学数理解析研究所の2021 年度訪問滞在型研究「Theory of operator algebras and its applications」による作用素環論の包括的研究を目指す.そのため複数の国際研究集会を開催するほか,その前後の期間に多数の研究者を招へいして,近年及び今後の作用素環論の動向について討議する.

Outline of Final Research Achievements

Amanability and Kazhdan's peoprty are the two most important concepts in analytic group theory. In the joint work with Yuhei Suzuki, the PI has proved that the several notions of amenability for group actions on operator algebras that have been proposed are all equivalent and given applications of this result. The elementary matrix group EL_d(R) for a finitely generated ring R is the most prominent example of groups with Kazhdan's property. The PI generalizes this fact to a non-unital ring. It is well-known that every operator on (the l_2 space of) a uniformly locally finite metric space that is approximable by finite-propagation operators is quasi-local. Since introduced in 90s, it has been questioned whether the converse also holds true. The PI has answered this in negative by constructing counterexamples.

Academic Significance and Societal Importance of the Research Achievements

群作用の従順性は群作用の研究において欠かすことのできない道具である。この理論を整備し、新たな例を与えた鈴木氏との共同研究成果には高い学術的価値がある。基本行列群は重要な研究対象であるが、無数の基本行列群を一斉に扱う際に非単位的な環を扱う必要が出てくる。環が非単位的になることにより、大きな技術的問題が生じるが、それを克服する初めての手法を見出したことの意義は大きい。近似的有限伝播性と擬局所性が同値であるか否かは粗距離空間上の作用素論における最重要未解決問題のひとつであった。確率論的手法による反例の構成は未解決問題を解決するのみならず、さらなる研究領域を切り開く重要な学術的進展である。

Report

(5 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Annual Research Report
  • 2021 Annual Research Report
  • 2020 Annual Research Report
  • Research Products

    (15 results)

All 2024 2023 2022 2021 2020 Other

All Int'l Joint Research (2 results) Journal Article (4 results) (of which Peer Reviewed: 4 results,  Open Access: 2 results) Presentation (6 results) (of which Int'l Joint Research: 5 results,  Invited: 6 results) Remarks (3 results)

  • [Int'l Joint Research] Fields Institute(カナダ)

    • Related Report
      2023 Annual Research Report
  • [Int'l Joint Research] KU Leuven(ベルギー)

    • Related Report
      2022 Annual Research Report
  • [Journal Article] Amenability for unitary groups of simple monotracial C*-algebras2024

    • Author(s)
      Narutaka Ozawa
    • Journal Title

      Muenster Journal of Mathematics

      Volume: -

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Journal Article] A substitute for Kazhdan's property (T) for universal non-lattices2024

    • Author(s)
      Narutaka Ozawa
    • Journal Title

      Analysis & PDE

      Volume: -

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed
  • [Journal Article] On characterizations of amenable C*-dynamical systems and new examples2021

    • Author(s)
      N. Ozawa and Y. Suzuki
    • Journal Title

      Selecta Mathematica

      Volume: 27 Issue: 5 Pages: 1-29

    • DOI

      10.1007/s00029-021-00699-2

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] An entropic proof of cutoff on Ramanujan graphs2020

    • Author(s)
      N. Ozawa
    • Journal Title

      Electron. Commun. Probab

      Volume: 77 Issue: none

    • DOI

      10.1214/20-ecp358

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Open Access
  • [Presentation] Kazhdan's property (T) for Aut(F_n) and EL_n(R)2023

    • Author(s)
      Narutaka Ozawa
    • Organizer
      Operator Algebras and Mathematical Physics
    • Related Report
      2023 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Amenability for unitary groups of C*-algebras2023

    • Author(s)
      Narutaka Ozawa
    • Organizer
      Workshop on Operator Algebras and Applications: Groups and Group Actions
    • Related Report
      2023 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] A substitute for Kazhdan's property (T) for universal non-lattices2023

    • Author(s)
      Narutaka Ozawa
    • Organizer
      Measured Group Theory
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Sum of squares methods for operator algebras2023

    • Author(s)
      Narutaka Ozawa
    • Organizer
      YMC*A at KU Leuven
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Amenability for C*-dynamical systems2022

    • Author(s)
      N. Ozawa
    • Organizer
      Operator algebras and Group Dynamics (CIRM)
    • Related Report
      2021 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] An entropic proof of cutoff on Ramanujan graphs2020

    • Author(s)
      N. Ozawa
    • Organizer
      Wales MPPM Seminar
    • Related Report
      2020 Annual Research Report
    • Invited
  • [Remarks] https://www.kurims.kyoto-u.ac.jp/~narutaka/

    • URL

      https://www.kurims.kyoto-u.ac.jp/~narutaka/

    • Related Report
      2023 Annual Research Report 2022 Annual Research Report
  • [Remarks]

    • URL

      https://www.kurims.kyoto-u.ac.jp/~narutaka/

    • Related Report
      2021 Annual Research Report
  • [Remarks]

    • URL

      https://www.kurims.kyoto-u.ac.jp/~narutaka/

    • Related Report
      2020 Annual Research Report

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Published: 2020-04-28   Modified: 2025-01-30  

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