Ryuya Hora洞龍弥

Exposés

2026

  1. 29 septembre 2026

    Titre à venir

    ItaCa Fest 2026 En ligne prévu

  2. 12 septembre 2026

    文字列から現代数学へ

    数学カフェ 先端講演 9F, Special Conference Room（特）, 台東区民会館, Tokyo prévu Vulgarisation

    Interactive slides (HTML)

  3. 5 septembre 2026

    圏論は役に立つのか：数学者とエンジニアの対話から考える夜

    圏論NIGHT 学術バーQ, Tokyo Avec Kory Vulgarisation

    Événement en collaboration avec Categories in Tokyo ; dialogue avec Kory.

    Inscription
    • Category
    Slides (HTML)

  4. 17 juillet 2026

    AIについて数学者は(何を)考えるべきか

    AI for Math勉強会 第2回 12F, Kabukiza Tower, Tokyo Vulgarisation

    Slides (HTML)

  5. 23 mai 2026

    ベン図からトポスへ

    Math Space Topos 2026 new welcome event Vulgarisation

    • Topos
    Diapositives (PDF)

  6. 6 avril 2026

    A Rota-Baxter equation for winning games

    Differentiation in category theory and program semantics Room 420, RIMS, Kyoto University

    Article: Differential calculus of impartial combinatorial games

    • Game
    Diapositives (PDF)

  7. 16 mars 2026

    A space⋊time for Conway’s Game of Life

    CSCAT 2026 Room 601A, AOSSA, Fukui

    Article: Dynamical systems on pretopological spaces

    • Dynamics
    Diapositives (PDF)

  8. 11 mars 2026

    Measure-theoretic closure operators on formal languages

    PPL 2026 Rexxam Hall, Takamatsu Avec Ryoma Sin'ya Poster

    Article: A note on language measurability

    • Automaton

  9. 22 février 2026

    Turning lights out with the Snake Lemma

    20th CGP project The University of Electro-Communications, Chofu Présenté par Kyosuke Higashida

    • Game
    Diapositives (PDF)

  10. 23 janvier 2026

    Connectedness and full subcategories of topoi

    Ph.D. thesis presentation Room 126, Graduate School of Mathematical Sciences, The University of Tokyo

    Articles: Grothendieck topoi with a left adjoint to a left adjoint to a left adjoint to the global sections functor · Solution to Lawvere's first problem: A Grothendieck topos that has proper class many quotient topoi · Lawvere's fourth open problem: Levels in the topos of symmetric simplicial sets

    • Topos
    • Category

2025

  1. 5 décembre 2025

    Local state classifier, The axiom of choice, and permutation model

    UTokyo Logic seminar Graduate School of Mathematical Sciences, The University of Tokyo

    Article: Local state classifier, permutation model, and the internal axiom of choice

    • Topos
    • Logique

  2. 28 novembre 2025

    Connectedness and full subcategories of topoi

    UTokyo Logic seminar Graduate School of Mathematical Sciences, The University of Tokyo

    Articles: Grothendieck topoi with a left adjoint to a left adjoint to a left adjoint to the global sections functor · Solution to Lawvere's first problem: A Grothendieck topos that has proper class many quotient topoi · Lawvere's fourth open problem: Levels in the topos of symmetric simplicial sets

    • Topos
    • Category

  3. 31 octobre 2025

    Topoi of automata

    SLACS 2025 Shared Room 321, Akita University, Tegata Campus

    Article: Topoi of automata I: Four topoi of automata and regular languages

    • Topos
    • Automaton
    Diapositives (PDF)

  4. 17 juillet 2025

    Topoi of automata

    CT 2025 Building B2, Faculty of Arts, Masaryk University, Brno

    Article: Topoi of automata I: Four topoi of automata and regular languages

    • Topos
    • Automaton
    Diapositives (PDF)

  5. 11 juin 2025

    A topos for regular language theory

    Theoretical Cosynus Seminar Henri Poincaré room, LIX, École polytechnique, Palaiseau

    Articles: Topoi of automata I: Four topoi of automata and regular languages · Internal parameterization of hyperconnected quotients

    • Topos
    • Automaton

  6. 5 juin 2025

    Local state classifier for automata theory

    Séminaires du LIPN Salle B107, LIPN, Université Sorbonne Paris Nord, Villetaneuse

    Mêmes diapositives que pour le séminaire Sémantique de l’IRIF.

    Articles: Topoi of automata I: Four topoi of automata and regular languages · Internal parameterization of hyperconnected quotients

    • Topos
    • Automaton
    Diapositives (PDF)

  7. 27 mai 2025

    Local state classifier for automata theory

    IRIF Sémantique seminar Salle 3071, IRIF, Université Paris Cité

    Articles: Topoi of automata I: Four topoi of automata and regular languages · Internal parameterization of hyperconnected quotients

    • Topos
    • Automaton
    Diapositives (PDF)

  8. 16 mai 2025

    Local state classifier for algebraic language theory

    Groupe de travail topossique Centre Lagrange, Paris

    Articles: Topoi of automata I: Four topoi of automata and regular languages · Internal parameterization of hyperconnected quotients

    • Topos
    • Automaton
    • Algèbre
    Diapositives (PDF)

  9. 6 mai 2025

    Topoi of automata

    Categories for Automata and Language Theory Salle 3071, IRIF, Université Paris Cité

    Article: Topoi of automata I: Four topoi of automata and regular languages

    • Topos
    • Automaton
    Diapositives (PDF)

  10. 30 avril 2025

    Topoi of automata

    Groupe de travail topossique Centre Lagrange, Paris

    Article: Topoi of automata I: Four topoi of automata and regular languages

    • Topos
    • Automaton
    Diapositives (PDF)

  11. 11 mars 2025

    Topoi of automata

    CSCAT 2025 Room F203, Sojo University, Kumamoto

    Article: Topoi of automata I: Four topoi of automata and regular languages

    • Topos
    • Automaton
    Diapositives (PDF)

  12. 28 février 2025

    Topoi of automata

    CMUP SAL seminar En ligne

    Event flyer

    Article: Topoi of automata I: Four topoi of automata and regular languages

    • Topos
    • Automaton

2024

  1. 30 novembre 2024

    Quotient topoi and geometry of computation

    AFSA area meeting Hall 401, TKP Kanda Business Center, Tokyo Vulgarisation

    • Topos
    • Géométrie

  2. 10 septembre 2024

    The colimit of all monomorphisms classifies hyperconnected geometric morphisms

    Toposes in Mondovì Circolo di Lettura, Palazzo del Governatore, Mondovì

    Vidéo

    Article: Internal parameterization of hyperconnected quotients

    • Topos

  3. 29 août 2024

    Topos theory as a tool of automata theory

    Young Automata Theorists Gathering in Japan Room 305, Akita University, Tegata Campus

    Article: Topoi of automata I: Four topoi of automata and regular languages

    • Topos
    • Automaton

  4. 28 juin 2024

    Quotient toposes of discrete dynamical systems

    CT 2024 Facultade de Matemáticas, Universidade de Santiago de Compostela

    Article: Quotient toposes of discrete dynamical systems

    • Topos
    • Dynamics

  5. 18 mai 2024

    アイゼンシュタイン整数と組合せ論

    Math Space Topos 2024 new welcome event Vulgarisation

    • Algèbre
    • Combinatoire
    Diapositives (PDF)

  6. 24 avril 2024

    圏論の利用と濫用

    18th AFSA Colloquium NII Kanda Lab, Tokyo

    • Category

  7. 16 mars 2024

    Introduction to topos theory

    代数トポロジー若手の会 Nagoya University

    • Topos

  8. 15 mars 2024

    Combinatorial games as recursive coalgebras

    CSCAT 2024 Multimedia Room 1, Science Building 4, Chiba University, Nishi-Chiba Campus

    Article: Games as recursive coalgebras: A categorical view on the Nim-sum

    • Game
    • Coalgebra
    • Algèbre
    Diapositives (PDF)

2023

  1. 10 décembre 2023

    Constructive mathematics and representation theory

    数学基礎論若手の会2023 Multipurpose Room Nalu, Sunset Breeze Hota, Kyonan, Chiba

    Article: A topos-theoretic view on Gabriel's theorem

    • Logique
    • Algèbre
    Diapositives (PDF)

  2. 21 août 2023

    Category Theory and Combinatorial Game Theory

    7th Japan Combinatorial Game Theory Conference National Institute of Informatics, Tokyo

    Article: Games as recursive coalgebras: A categorical view on the Nim-sum

    • Game
    • Category

  3. 15 juillet 2023

    母関数の種

    Math Space Topos 2023 new welcome event Vulgarisation

    • Combinatoire
    Diapositives (PDF)

  4. 6 juillet 2023

    Internal parameterization of hyperconnected quotients

    Category Theory 2023 Auditoires des Sciences, UCLouvain, Louvain-la-Neuve

    Vidéo

    Article: Internal parameterization of hyperconnected quotients

    • Topos

  5. 12 mai 2023

    Grundy Numbers and Categories

    Japan Combinatorial Game Theory Mini-Workshops with Urban Larsson National Institute of Informatics, Tokyo

    Article: Games as recursive coalgebras: A categorical view on the Nim-sum

    • Game
    • Category

  6. 19 avril 2023

    Internal parameterization of hyperconnected quotients

    Australian Category Seminar En ligne

    Article: Internal parameterization of hyperconnected quotients

    • Topos

  7. 10 mars 2023

    Internal parameterization of hyperconnected quotients

    CSCAT 2023 Room 478, Research Building 2, Kyoto University, Yoshida Campus

    Article: Internal parameterization of hyperconnected quotients

    • Topos

2022

  1. 4 juin 2022

    順序集合で遊ぶKan拡張

    Math Space Topos 2022 new welcome event Vulgarisation

    • Category
    Diapositives (PDF)

2021

  1. 4 décembre 2021

    ゼータ関数とメビウス反転

    Math Space Topos 2021 new welcome event Vulgarisation

    • Combinatoire
    Diapositives (PDF)