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The search for ergodic Ramsey theory and Erdos conjecture toward the construction of infinite ergodic theory

Research Project

Project/Area Number 20K03642
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 12010:Basic analysis-related
Research InstitutionJapan Women's University

Principal Investigator

Natsui Rie  日本女子大学, 理学部, 教授 (60398633)

Project Period (FY) 2020-04-01 – 2025-03-31
Project Status Completed (Fiscal Year 2024)
Budget Amount *help
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2023: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
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: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Keywords連分数変換 / 数論的アルゴリズム / エルゴード理論 / 複素連分数変換 / natural extension / ユークリッドアルゴリズム / ラムゼー理論 / 測度論的数論
Outline of Research at the Start

エルゴード理論的研究から無限大不変測度を持つ可測力学系の分類・特徴付けを行い、一般的体系を築く目的に向かって、この系におけるdeterminismとrandomnessの概念に着目し、具体的かつ多様な数論的変換の研究を通して、これらの概念の違いを捉える新たな不変量を見出すことにより系の分類問題へと発展させ、特徴付けを行う。特に、Erdos予想との関連を強く意識し、意義のある無限大不変測度を持つエルゴード変換に着目する。そして、本研究を通して ergodic Ramsey theoryの追究を軸に、測度論的数論への応用など従来のエルゴード理論の枠に留まることなく様々な分野との連携を目指した横断的な研究を行う。

Outline of Final Research Achievements

Aiming to find the invariant that capture randomness in measurable dynamical systems with infinite invariant measure for which no general system has been constructed, we sought a foothold through ergodic theoretical research on various number-theoretic transformations.
Mainly, the ergodic theoretical research on various types of complex continued fraction transformations over imaginary quadratic fields, and on the transformations to derive number-theoretic algorithms for polynomials over finite fields, has enabled me to grasp the complex behavior of numbers in measure theory.

Academic Significance and Societal Importance of the Research Achievements

本研究成果は、連分数変換やユークリッドアルゴリズムをはじめとする数展開を導出する変換のエルゴード理論的研究から数の複雑な振る舞いの一端を測度論的に解き明かすことができたことにある。数の振る舞いの複雑さを解き明かすことは、例えば、暗号技術、情報技術への応用にも繋がり、その社会的意義も大きいと考える。また、学術的には僅かではあるが、無限大不変測度を持つ可測力学系のエルゴード理論、並びに、測度論的数論の研究に寄与した意義を持つ。

Report

(6 results)
  • 2024 Annual Research Report   Final Research Report ( PDF )
  • 2023 Research-status Report
  • 2022 Research-status Report
  • 2021 Research-status Report
  • 2020 Research-status Report
  • Research Products

    (10 results)

All 2025 2024 2023 2022 2021 Other

All Int'l Joint Research (2 results) Journal Article (4 results) (of which Int'l Joint Research: 1 results,  Peer Reviewed: 4 results) Presentation (4 results) (of which Invited: 1 results)

  • [Int'l Joint Research] Delft University of Technology/Utrecht University(オランダ)

    • Related Report
      2024 Annual Research Report
  • [Int'l Joint Research] TUDelft/Utrecht University(オランダ)

    • Related Report
      2023 Research-status Report
  • [Journal Article] On the dynamics of a complex continued fraction map which contains the Gauss map as its real number section2025

    • Author(s)
      Ei Hiromi、Nakada Hitoshi、Natsui Rie
    • Journal Title

      Advances in Mathematics

      Volume: 472 Pages: 110286-110286

    • DOI

      10.1016/j.aim.2025.110286

    • Related Report
      2024 Annual Research Report
    • Peer Reviewed
  • [Journal Article] ON THE ERGODIC THEORY OF MAPS ASSOCIATED WITH THE NEAREST INTEGER COMPLEX CONTINUED FRACTIONS OVER IMAGINARY QUADRATIC FIELDS2023

    • Author(s)
      Hiromi Ei, Hitoshi Nakada, Rie Natsui
    • Journal Title

      Discrete and Continuous Dynamical Systems

      Volume: 43(11) Issue: 11 Pages: 3883-3924

    • DOI

      10.3934/dcds.2023071

    • Related Report
      2023 Research-status Report
    • Peer Reviewed
  • [Journal Article] On the existence of the Legendre constants for some complex continued fraction expansions over imaginary quadratic fields2022

    • Author(s)
      Hiromi Ei, Hitoshi Nakada, Rie Natsui
    • Journal Title

      Journal of Number Theory

      Volume: 238 Pages: 106-132

    • DOI

      10.1016/j.jnt.2021.08.004

    • Related Report
      2022 Research-status Report
    • Peer Reviewed
  • [Journal Article] Analysis of generalized continued fraction algorithms over polynomials2021

    • Author(s)
      Valerie Berthe, Hitoshi Nakada, Rie Natsui, Brigitte Vallee
    • Journal Title

      Finite Fields and Their Applications

      Volume: 73 Pages: 101849-101849

    • DOI

      10.1016/j.ffa.2021.101849

    • Related Report
      2021 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Presentation] エルゴード理論と測度論的数論2024

    • Author(s)
      夏井利恵
    • Organizer
      第7回岡潔女性数学者セミナー
    • Related Report
      2024 Annual Research Report
    • Invited
  • [Presentation] パーコレーション理論を用いた学習効果の分析と臨界確率の考察2024

    • Author(s)
      穂高あかり, 夏井利恵
    • Organizer
      2024年度数学教育学会春季年会
    • Related Report
      2023 Research-status Report
  • [Presentation] パーコレーション理論を用いた学習効果の分析2023

    • Author(s)
      穂高あかり, 夏井利恵
    • Organizer
      2023年度数学教育学会秋季例会
    • Related Report
      2023 Research-status Report
  • [Presentation] On the group extension of a complex continued fraction map2022

    • Author(s)
      Rie Natsui
    • Organizer
      Recent Progress in Ergodic Theory
    • Related Report
      2021 Research-status Report

URL: 

Published: 2020-04-28   Modified: 2026-01-16  

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