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Last Updated :2025/09/17

Tadashi Fujioka

Faculty of Science
Assistant Lecturer/Assistant professor

ProfileI'm interested in Riemannian manifolds with sectional curvature bounded below or above and their limit spaces, i.e., Alexandrov spaces, CAT spaces, and Busemann spaces. Here you can mainly find the abstracts and slides of my talks. For other materials available elsewhere, such as my papers, please see the attached links.Contact Pointtfujioka210@gmail.com

Researcher information

■ Degree
  • Doctor of Science, Kyoto University, Mar. 2021
■ Research Keyword
  • Riemannian Geometry
  • Alexandrov Geometry
  • Busemann Geometry
  • Convergence Theory
■ Field Of Study
  • Natural sciences, Geometry

Career

■ Career
  • Sep. 2025 - Present
    Fukuoka University, Department of Applied Mathematics, Faculty of Science, Assistant Professor
  • Apr. 2025 - Aug. 2025
    Kyoto University, Department of Mathematics, Graduate School of Science, Program-Specific Assistant Professor
  • Apr. 2022 - Mar. 2025
    Osaka University, Department of Mathematics, Graduate School of Science, JSPS Postdoctoral Fellow
  • Apr. 2022 - Sep. 2022
    Osaka University, Department of Mathematics, Graduate School of Science, Part-time Lecturer
  • Apr. 2021 - Mar. 2022
    Kyoto University, Department of Mathematics, Graduate School of Science, Part-time Postdoctoral Fellow and Teaching Assistant
■ Educational Background
  • Apr. 2017 - Mar. 2021
    Kyoto University, Graduate School of Science, Doctoral Course, Division of Mathematics
  • Apr. 2015 - Mar. 2017
    Kyoto University, Graduate School of Science, Master's Course, Division of Mathematics
  • Apr. 2011 - Mar. 2015
    Kyoto University, Faculty of Science, Department of Science

Research activity information

■ Award
  • Sep. 2025
    日本数学会, 建部賢弘特別賞
    Japan society
■ Paper
  • Topological regularity of Busemann spaces of nonpositive curvature
    Tadashi Fujioka; Shijie Gu
    arXiv, 20 Apr. 2025, :2504.14455
    Corresponding
  • Uniform boundedness on extremal subsets in Alexandrov spaces
    Tadashi Fujioka
    The Journal of Geometric Analysis, 21 Dec. 2024, 35(2):46, Refereed
  • Alexandrov spaces are CS sets
    Tadashi Fujioka
    arXiv, 22 Apr. 2024, :2404.14587
  • Euler characteristics of collapsing Alexandrov spaces
    Tadashi Fujioka
    Arnold Mathematical Journal, 18 Mar. 2024, 10(4):463 - 472, Refereed
  • A lower bound for the curvature integral under an upper curvature bound
    Tadashi Fujioka
    Algebra i Analiz, Mar. 2024, 36(2):131 - 160, Refereed
  • Extremal subsets in geodesically complete spaces with curvature bounded above
    Tadashi Fujioka
    Analysis and Geometry in Metric Spaces, 31 Dec. 2023, 11(1):20230104, Refereed
  • Lipschitz homotopy convergence of Alexandrov spaces II
    Tadashi Fujioka; Ayato Mitsuishi; Takao Yamaguchi
    arXiv, 25 Apr. 2023, :2304.12515
    Corresponding
  • A fibration theorem for collapsing sequences of Alexandrov spaces
    Tadashi Fujioka
    Journal of Topology and Analysis, Mar. 2023, 15(1):265 - 298, Refereed
  • Collapsing to Alexandrov spaces with isolated mild singularities
    Tadashi Fujioka
    Differential Geometry and its Applications, Dec. 2022, 85:101951, Refereed
  • Regular points of extremal subsets in Alexandrov spaces
    Tadashi Fujioka
    Journal of the Mathematical Society of Japan, 25 Oct. 2022, 74(4):1245 - 1268, Refereed
  • Noncritical maps on geodesically complete spaces with curvature bounded above
    Tadashi Fujioka
    Annals of Global Analysis and Geometry, Oct. 2022, 62(3):661 - 677, Refereed
  • Application of good coverings to collapsing Alexandrov spaces
    Tadashi Fujioka
    Pacific Journal of Mathematics, 06 Apr. 2022, 316(2):335 - 365, Refereed
■ MISC
  • Fibration theorems for collapsing Alexandrov spaces
    Tadashi Fujioka
    Doctoral thesis, Mar. 2021
  • Alexandrov空間のextremal subsetに関する諸定理
    Tadashi Fujioka
    Master's thesis, Mar. 2017
■ Lectures, oral presentations, etc.
  • Curvature bounds and the manifold recognition
    藤岡 禎司
    福岡大学微分幾何セミナー, 11 Sep. 2025
  • Busemann非正曲率空間のトポロジー
    藤岡 禎司
    京都大学談話会, 16 Jul. 2025
  • Busemann NPC 4-manifolds are Euclidean
    藤岡 禎司
    確率論と幾何学2025, 24 Jun. 2025
  • Curvature bounds and the manifold recognition
    藤岡 禎司
    対称性と幾何セミナー, 19 Jun. 2025
  • Topological regularity of Busemann spaces
    Tadashi Fujioka
    OIST Analysis on Metric Spaces Unit Seminar, 04 Jun. 2025
  • 球面定理再訪
    藤岡 禎司
    福岡大学微分幾何研究集会, 17 Feb. 2025
  • Riemann幾何学とその先：Alexandrov幾何学入門
    藤岡 禎司
    第8回数理新人セミナー, 12 Feb. 2025
  • Busemann非正曲率空間のトポロジー
    藤岡 禎司
    大阪大学幾何セミナー, 27 Jan. 2025
  • Alexandrov空間のstratification再訪
    藤岡 禎司
    測地線及び関連する諸問題, 04 Jan. 2025
  • Curvature bounds and the curvature integrals
    藤岡 禎司
    One-day Workshop on Geometry at Nagoya, 06 Dec. 2024
  • Finiteness and continuity under a lower or upper curvature bound
    藤岡 禎司
    第71回幾何学シンポジウム, 13 Sep. 2024
  • 曲率の下界をもつ空間のstratificationについて
    藤岡 禎司
    日本数学会2024年度秋季総合分科会（トポロジー分科会）, 05 Sep. 2024
  • 正曲率ホモロジー多様体とリンクに対する球面定理
    藤岡 禎司
    日本数学会2024年度秋季総合分科会（幾何学分科会）, 05 Sep. 2024
  • 曲率の上界と曲率積分の下界
    藤岡 禎司
    日本数学会2024年度年会, 19 Mar. 2024
  • Upper curvature bound and the curvature integral
    藤岡 禎司
    リーマン幾何と幾何解析, 20 Feb. 2024
  • Upper curvature bound and the curvature integral
    藤岡 禎司
    測地線及び関連する諸問題, 04 Jan. 2024
  • Upper curvature bound and the curvature integral
    Tadashi Fujioka
    Pennsylvania State University Geometry Seminar, 11 Oct. 2023
  • 崩壊するAlexandrov空間のEuler標数
    藤岡 禎司
    日本数学会2023年度秋季総合分科会, 23 Sep. 2023
  • Alexandrov空間の定量的Lipschitzホモトピー収束
    藤岡 禎司; 三石 史人; 山口 孝男
    日本数学会2023年度秋季総合分科会, 23 Sep. 2023
  • Upper curvature bound and the curvature integral
    Tadashi Fujioka
    The 8th China-Japan Geometry Conference, 09 Sep. 2023
  • Alexandrov空間の収束・崩壊理論における良い被覆の応用
    藤岡 禎司
    福岡大学微分幾何セミナー, 06 Jul. 2023
  • Collapsing phenomena of Alexandrov spaces
    藤岡 禎司
    Tsukuba Global Riemannian Geometry, 06 Mar. 2023
  • Quantitative Lipschitz homotopy convergence of Alexandrov spaces
    Tadashi Fujioka
    Geometry and Probability 2022, 16 Feb. 2023
  • 崩壊するAlexandrov空間のEuler標数
    藤岡 禎司
    測地線及び関連する諸問題, 04 Jan. 2023
  • Extremal subsets in CBB and GCBA geometries
    Tadashi Fujioka
    Workshop on Geometry of Upper and Lower Curvature Bounds, 12 Sep. 2022
  • 曲率の上界をもつ空間のextremal subset
    藤岡 禎司
    第69回幾何学シンポジウム, 01 Sep. 2022
  • 曲率の上界をもつ空間に対する球面定理
    藤岡 禎司
    確率論と幾何学2021, 16 Mar. 2022
  • Noncritical maps on geodesically complete spaces with curvature bounded above
    Tadashi Fujioka
    The 7th KTGU Mathematics Workshop for Young Researchers, 14 Feb. 2022
  • 曲率の上界をもつ空間上の正則写像
    藤岡 禎司
    測地線及び関連する諸問題, 04 Jan. 2022
  • 曲率の上界をもつ空間上の正則写像
    藤岡 禎司
    大阪大学幾何セミナー, 18 Oct. 2021
  • 弱い孤立特異点をもつAlexandrov空間への崩壊
    藤岡 禎司
    日本数学会2021年度秋季総合分科会, 14 Sep. 2021
  • 弱い孤立特異点をもつAlexandrov空間への崩壊
    藤岡 禎司
    東北大学幾何セミナー, 20 Jul. 2021
  • 弱い孤立特異点をもつAlexandrov空間への崩壊
    藤岡 禎司
    福岡大学微分幾何セミナー, 08 Jul. 2021
  • 崩壊するAlexandrov空間のSerreファイブレーション構造
    藤岡 禎司
    日本数学会2021年度年会, 17 Mar. 2021
  • 崩壊するAlexandrov空間のファイブレーション構造について
    藤岡 禎司
    リーマン幾何と幾何解析, 12 Feb. 2021
  • Fibration theorems for collapsing Alexandrov spaces
    藤岡 禎司
    京都大学微分トポロジーセミナー, 10 Nov. 2020
  • Alexandrov空間の崩壊列に対するファイブレーション定理
    藤岡 禎司
    日本数学会2020年度秋季総合分科会, 24 Sep. 2020
  • Alexandrov空間の崩壊列に対するファイブレーション定理
    藤岡 禎司
    第67回幾何学シンポジウム, 01 Sep. 2020
  • Alexandrov空間のextremal subsetに関する諸定理
    藤岡 禎司
    リーマン幾何と幾何解析, 14 Feb. 2020
■ Courses
  • 微分積分II（TC-a）
    Sep. 2025 - Present
    福岡大学
  • 微分積分学A（演義）
    Apr. 2025 - Aug. 2025
    京都大学
  • 幾何学基礎1演義
    Apr. 2022 - Sep. 2022
    大阪大学
■ Affiliated academic society
  • Apr. 2020 - Present
    The Mathematical Society of Japan
■ Research Themes
  • 曲率の上界と下界の幾何学・収束理論
    Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Research Activity Start-up
    Kyoto University
    Jul. 2025 - Mar. 2027
  • アレクサンドロフ空間の幾何学と崩壊理論
    Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for JSPS Fellows
    Osaka University
    Apr. 2022 - Mar. 2025
■ Academic Contribution Activities
  • 福岡大学微分幾何講座
    Planning etc
    Sep. 2025, Present
  • Mathematical Reviews
    Review
    American Mathematical Society, Jan. 2023, Present
  • The 18th MSJ-SI: Analysis, Geometry and Probability on Metric Measure Spaces
    Planning etc
    The Mathematical Society of Japan, 09 Feb. 2026, 20 Feb. 2026