Ryuya Hora洞龍弥

Ryuya Hora 洞龍弥

Assistant Professor à l’université ZEN

ryuya_hora@zen.ac.jp · horaryuya38@gmail.com · ryuyahora.jp · Tokyo, Japon

ORCID · researchmap · arXiv · nLab

Domaines de recherche

Formation

Postes

Financements et bourses

Distinctions

Articles

  1. Yuhi Kamio, Ryuya Hora. Solution to Lawvere's first problem: A Grothendieck topos that has proper class many quotient topoi. Advances in Mathematics 487, 110751, 2026. DOI · arXiv
  2. Ryuya Hora. Grothendieck topoi with a left adjoint to a left adjoint to a left adjoint to the global sections functor. Proceedings of the American Mathematical Society 154(2), 567-584, 2026. DOI · arXiv
  3. Ryuya Hora. Normalization of a subgroup, in a topos, and of a word-congruence. arXiv:2511.05012 (prépublication), 2025. arXiv · PDF
  4. Ryuya Hora. Games as recursive coalgebras: A categorical view on the Nim-sum. arXiv:2510.22886 (prépublication), 2025. arXiv
  5. Ryuya Hora, Yuhi Kamio, Yuki Maehara. Lawvere's fourth open problem: Levels in the topos of symmetric simplicial sets. arXiv:2503.03439 (prépublication), 2025. arXiv
  6. Ryuya Hora. Topoi of automata I: Four topoi of automata and regular languages. arXiv:2411.06358 (prépublication), 2024. arXiv
  7. Ryuya Hora. Internal parameterization of hyperconnected quotients. Theory and Applications of Categories 42(11), 263-313, 2024. DOI · TAC · arXiv
  8. Ryuya Hora, Yuhi Kamio. Quotient toposes of discrete dynamical systems. Journal of Pure and Applied Algebra 228(8), 107657, 2024. DOI · arXiv

En préparation

Exposés et notes

Exposés et présentations

2026

  1. Titre à venir. ItaCa Fest 2026, en ligne, 29 septembre 2026. prévu.
  2. 文字列から現代数学へ. 数学カフェ 先端講演, Tokyo, Japan, 12 septembre 2026. prévu. Vulgarisation.
  3. 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 (Ryuya Hora, Kory). 圏論NIGHT, Tokyo, Japan, 5 septembre 2026. Vulgarisation.
  4. 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, Tokyo, Japan, 17 juillet 2026. Vulgarisation.
  5. ベン図からトポスへ. Math Space Topos 2026 new welcome event, 23 mai 2026. Vulgarisation.
  6. A Rota-Baxter equation for winning games. Differentiation in category theory and program semantics, Kyoto, Japan, 6 avril 2026.
  7. A space⋊time for Conway’s Game of Life. CSCAT 2026, Fukui, Japan, 16 mars 2026.
  8. Measure-theoretic closure operators on formal languages (Ryuya Hora, Ryoma Sin'ya). PPL 2026, Takamatsu, Japan, 11 mars 2026. Poster.
  9. Turning lights out with the Snake Lemma (Kyosuke Higashida). 20th CGP project, Chofu, Japan, 22 février 2026.
  10. Connectedness and full subcategories of topoi. Ph.D. thesis presentation, Tokyo, Japan, 23 janvier 2026.

2025

  1. Local state classifier, The axiom of choice, and permutation model. UTokyo Logic seminar, Tokyo, Japan, 5 décembre 2025.
  2. Connectedness and full subcategories of topoi. UTokyo Logic seminar, Tokyo, Japan, 28 novembre 2025.
  3. Topoi of automata. SLACS 2025, Akita, Japan, 31 octobre 2025.
  4. Topoi of automata. CT 2025, Brno, Czech Republic, 17 juillet 2025.
  5. A topos for regular language theory. Theoretical Cosynus Seminar, Palaiseau, France, 11 juin 2025.
  6. Local state classifier for automata theory. Séminaires du LIPN, Villetaneuse, France, 5 juin 2025.
  7. Local state classifier for automata theory. IRIF Sémantique seminar, Paris, France, 27 mai 2025.
  8. Local state classifier for algebraic language theory. Groupe de travail topossique, Paris, France, 16 mai 2025.
  9. Topoi of automata. Categories for Automata and Language Theory, Paris, France, 6 mai 2025.
  10. Topoi of automata. Groupe de travail topossique, Paris, France, 30 avril 2025.
  11. Topoi of automata. CSCAT 2025, Kumamoto, Japan, 11 mars 2025.
  12. Topoi of automata. CMUP SAL seminar, en ligne, 28 février 2025.

2024

  1. Quotient topoi and geometry of computation. AFSA area meeting, Tokyo, Japan, 30 novembre 2024. Vulgarisation.
  2. The colimit of all monomorphisms classifies hyperconnected geometric morphisms. Toposes in Mondovì, Mondovì, Italy, 10 septembre 2024.
  3. Topos theory as a tool of automata theory. Young Automata Theorists Gathering in Japan, Akita, Japan, 29 août 2024.
  4. Quotient toposes of discrete dynamical systems. CT 2024, Santiago de Compostela, Spain, 28 juin 2024.
  5. アイゼンシュタイン整数と組合せ論. Math Space Topos 2024 new welcome event, 18 mai 2024. Vulgarisation.
  6. 圏論の利用と濫用. 18th AFSA Colloquium, Tokyo, Japan, 24 avril 2024.
  7. Introduction to topos theory. 代数トポロジー若手の会, Nagoya, Japan, 16 mars 2024.
  8. Combinatorial games as recursive coalgebras. CSCAT 2024, Chiba, Japan, 15 mars 2024.

2023

  1. Constructive mathematics and representation theory. 数学基礎論若手の会2023, Kyonan, Chiba, Japan, 10 décembre 2023.
  2. Category Theory and Combinatorial Game Theory. 7th Japan Combinatorial Game Theory Conference, Tokyo, Japan, 21 août 2023.
  3. 母関数の種. Math Space Topos 2023 new welcome event, 15 juillet 2023. Vulgarisation.
  4. Internal parameterization of hyperconnected quotients. Category Theory 2023, Louvain-la-Neuve, Belgium, 6 juillet 2023.
  5. Grundy Numbers and Categories. Japan Combinatorial Game Theory Mini-Workshops with Urban Larsson, Tokyo, Japan, 12 mai 2023.
  6. Internal parameterization of hyperconnected quotients. Australian Category Seminar, en ligne, 19 avril 2023.
  7. Internal parameterization of hyperconnected quotients. CSCAT 2023, Kyoto, Japan, 10 mars 2023.

2022

  1. 順序集合で遊ぶKan拡張. Math Space Topos 2022 new welcome event, 4 juin 2022. Vulgarisation.

2021

  1. ゼータ関数とメビウス反転. Math Space Topos 2021 new welcome event, 4 décembre 2021. Vulgarisation.

Enseignement, vulgarisation et service