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A study on fixed point problems in metric spaces with geodesic structure and its applications

Research Project

Project/Area Number 17K05372
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Research Field Foundations of mathematics/Applied mathematics
Research InstitutionTokai University

Principal Investigator

Kohsaka Fumiaki  東海大学, 理学部, 教授 (20434003)

Project Period (FY) 2017-04-01 – 2021-03-31
Project Status Completed (Fiscal Year 2020)
Budget Amount *help
¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Fiscal Year 2020: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2018: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Keywords非線形解析学 / 凸解析学 / 不動点定理 / 不動点近似 / 凸関数 / 測地距離空間 / ヒルベルト空間 / バナッハ空間 / 不動点 / 非拡大写像 / 強非拡大写像 / Bregman距離 / 完備CAT(0)空間 / 最小点 / 近接点法 / CAT(0)空間 / CAT(1)空間 / ヒルベルト球面 / レゾルベント / アダマール空間 / 最小点近似 / 共通不動点 / Bregman distance / 制約可能性問題 / 非線形解析 / 凸解析 / 不動点理論 / 非線形問題 / 測地的距離空間
Outline of Final Research Achievements

In this research, we study fixed point problems for mappings defined on geodesic metric spaces and normed spaces and apply our results to minimization problems for convex functions and convex feasibility problems in such spaces. In particular, we obtain some results on the existence and approximation of fixed points for mappings defined on complete geodesic metric spaces. Further, we also study the asymptotic behavior of sequences generated by using resolvents of convex functions. We also obtain fixed point theorems and fixed point approximation theorems with two variable functions associated with smooth convex functions in Banach spaces.

Academic Significance and Societal Importance of the Research Achievements

物理現象や社会現象を数学的に定式化した際に現れる非線形問題を統一的に解決する方法の一つとして、非線形写像に対する不動点理論を用いる方法がある。本研究では、数列空間や関数空間などの無限次元完備ノルム空間や球面や双曲面などの完備測地距離空間における種々の写像に対する不動点問題の研究を行った。特に、不動点の存在性や不動点の近似方法に関する研究成果が得られた。さらに、これらの成果を応用することにより、凸関数の最小化問題や凸制約可能性問題などの非線形問題に関する結果を得た。本研究の研究成果により、球面や双曲面などの非線形空間における諸問題を不動点理論の枠組みで解決する方法が示された。

Report

(5 results)
  • 2020 Annual Research Report   Final Research Report ( PDF )
  • 2019 Research-status Report
  • 2018 Research-status Report
  • 2017 Research-status Report
  • Research Products

    (32 results)

All 2021 2020 2019 2018 2017 Other

All Int'l Joint Research (2 results) Journal Article (8 results) (of which Peer Reviewed: 7 results,  Open Access: 7 results) Presentation (21 results) (of which Int'l Joint Research: 17 results,  Invited: 12 results) Remarks (1 results)

  • [Int'l Joint Research] Khon Kaen University/モンクッド王立工科大学(タイ)

    • Related Report
      2019 Research-status Report
  • [Int'l Joint Research] King Mongkut's University of Technology/Khon Kaen University(タイ)

    • Related Report
      2018 Research-status Report
  • [Journal Article] Strongly quasinonexpansive mappings, III2020

    • Author(s)
      Koji Aoyama and Fumiaki Kohsaka
    • Journal Title

      Linear and Nonlinear Analysis

      Volume: 6, No.1

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Fixed points of metrically nonspreading mappings in Hadamard spaces2019

    • Author(s)
      Fumiaki Kohsaka
    • Journal Title

      Applied Analysis and Optimization

      Volume: 3-2

    • Related Report
      2019 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Two modified proximal point algorithms in geodesic spaces with curvature bounded above2019

    • Author(s)
      Yasunori Kimura and Fumiaki Kohsaka
    • Journal Title

      Rendiconti del Circolo Matematico di Palermo Series 2

      Volume: 68-1 Issue: 1 Pages: 83-104

    • DOI

      10.1007/s12215-018-0340-3

    • Related Report
      2018 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] ヒルベルト空間における二つの可換なhybrid写像の共通不動点2018

    • Author(s)
      高阪史明
    • Journal Title

      京都大学数理解析研究所講究録

      Volume: 2065

    • Related Report
      2018 Research-status Report
  • [Journal Article] Existence and approximation of fixed points of vicinal mappings in geodesic spaces2018

    • Author(s)
      Fumiaki Kohsaka
    • Journal Title

      Pure and Applied Functional Analysis

      Volume: 3-1

    • Related Report
      2017 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Existence and approximation of fixed points of Chatterjea mappings with Bregman distances2017

    • Author(s)
      Fumiaki Kohsaka and Tomonari Suzuki
    • Journal Title

      Linear and Nonlinear Analysis

      Volume: 3-1

    • Related Report
      2017 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] The proximal point algorithm in geodesic spaces with curvature bounded above2017

    • Author(s)
      Yasunori Kimura and Fumiaki Kohsaka
    • Journal Title

      Linear and Nonlinear Analysis

      Volume: 3-1

    • Related Report
      2017 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Cutter mappings and subgradient projections in Banach spaces2017

    • Author(s)
      Koji Aoyama and Fumiaki Kohsaka
    • Journal Title

      Linear and Nonlinear Analysis

      Volume: 3-3

    • Related Report
      2017 Research-status Report
    • Peer Reviewed / Open Access
  • [Presentation] アダマール空間における凸関数の最小点近似2021

    • Author(s)
      高阪史明
    • Organizer
      京都大学数理解析研究所研究集会 非線形解析学と凸解析学の研究
    • Related Report
      2020 Annual Research Report
  • [Presentation] On metric completeness and some preservations of convex metric spaces in the sense of Takahashi2019

    • Author(s)
      Pinya Ardsalee, Fumiaki Kohsaka, Jenjira Puiwong, and Satit Saejung
    • Organizer
      International Conference on Nonlinear Analysis and Convex Analysis--International Conference on Optimization: Techniques and Applications (NACA-ICOTA2019), August 26--31, 2019
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research
  • [Presentation] Fixed points of metrically nonspreading mappings in Hadamard spaces2019

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      International Conference on Nonlinear Analysis and Convex Analysis--International Conference on Optimization: Techniques and Applications (NACA-ICOTA2019), August 26--31, 2019
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research
  • [Presentation] Finding fixed points of metrically nonspreading mappings in Hadamard spaces2019

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The 2nd International Workshop on Applied Nonlinear Analysis (IWANA2019), Bangsaen, Chonburi, Thailand, September 12--14, 2019
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Firmly nonexpansive like mappings in Banach spaces2019

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      Workshop on "Convex Analysis on Geodesic Spaces", Khon Kaen University, Khon Kaen, Thailand, September 17--18, 2019
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Metrically nonspreading mappings2019

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      Workshop on "Convex Analysis on Geodesic Spaces", Khon Kaen University, Khon Kaen, Thailand, September 17--18, 2019
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Fixed point problems for firmly nonexpansive like mappings in Banach spaces2019

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      14th International Seminar on Optimization and Related Areas (ISORA), the Instituto de Matematica y Ciencias Afines (IMCA), Lima, Peru, October 7--11, 2019
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] The proximal point algorithm for convex functions in geodesic spaces2018

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      A seminar on Nonlinear Analysis and Applications, Tokai University, Hiratsuka, Japan, April 4, 2018
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research
  • [Presentation] Fixed points of vicinal mappings in complete CAT(1) spaces2018

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The 10th Asian Conference on Fixed Point Theory and Optimization, The Empress Hotel, Chiang Mai, Thailand, July 16--18, 2018
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Recent results on the resolvents of convex functions in geodesic spaces2018

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The Inthernational Symposium on Nonlinear Convex Analysis and Optimization 2018, King Mongkut's University of Technology Thonburi, Bangkok, Thailand, July 19--22, 2018
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Fixed points of vicinal mappings and convex optimization in geodesic metric spaces2018

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The Inthernational Workshop on Variational Analysis and Applications, Ettore Majorana Foundation and Centre for Scientific Culture, Erice--Sicily, Italy, August 28--September 5, 2018
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research
  • [Presentation] Fixed points of nonspreading mappings and its relatives in Banach spaces2018

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The Seminar on Fixed Point Theory and Optimization, Khon Kaen University, Khon Kaen, Thailand, September 12, 2018
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Fundamental properties of resolvents of convex functions in geodesic spaces2018

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The Seminar on Fixed Point Theory and Optimization, Khon Kaen University, Khon Kaen, Thailand, September 12, 2018
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Fixed points of Chatterjea mappings with Bregman distances in Banach spaces2018

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The 6th Asian Conference on Nonlinear Analysis and Optimization, ANA Intercontinental Manza Beach Resort, Onna-son, Okinawa, Japan, November 5--9, 2018
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] 完備CAT(1)空間における凸関数の最小点近似2018

    • Author(s)
      高阪史明
    • Organizer
      日本数学会2019年度年会, 東京工業大学理学院数学系, 2019年3月17日--20日
    • Related Report
      2018 Research-status Report
  • [Presentation] The proximal point algorithm and its variants for convex functions in geodesic metric spaces2017

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The 10th Anniversary International Conference on Nonlinear Analysis and Convex Analysis, Chitose City Cultural Center, Chitose, Japan, July 4--9, 2017
    • Related Report
      2017 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Approximating minimizers of convex functions in geodesic metric spaces with curvature bounded above2017

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      XII International Symposium on Generalized Convexity and Monotonicity, Hajduszoboszlo, Hungary, August 27--September 2, 2017
    • Related Report
      2017 Research-status Report
    • Int'l Joint Research
  • [Presentation] The resolvents of convex functions in geodesic metric spaces2017

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The Workshop Convex Analysis in CAT(k) Spaces, King Mongkut's University of Technology Thonburi, Bangkok, Thailand, September 8--9, 2017
    • Related Report
      2017 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Fixed point problems for spherically nonspreading mappings and vicinal mappings in CAT(1) spaces2017

    • Author(s)
      Fumiaki Kohsaka
    • Organizer
      The Workshop Convex Analysis in CAT(k) Spaces, King Mongkut's University of Technology Thonburi, Bangkok, Thailand, September 8--9, 2017
    • Related Report
      2017 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] 上に有界な曲率を持つ完備測地的距離空間におけるspherically nonspreading写像の不動点2017

    • Author(s)
      高阪史明
    • Organizer
      2017年度秋季総合分科会, 山形大学小石川キャンパス, 2017年9月11日--14日
    • Related Report
      2017 Research-status Report
  • [Presentation] 完備CAT(1)空間における凸関数に対する近接点法2017

    • Author(s)
      高阪史明
    • Organizer
      日本数学会2018年度年会, 東京大学大学院数理科学研究科, 2018年3月18日--21日
    • Related Report
      2017 Research-status Report
  • [Remarks] https://sites.google.com/site/fumiakikohsaka/home

    • Related Report
      2019 Research-status Report

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Published: 2017-04-28   Modified: 2022-01-27  

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