Ryuya Hora洞龍弥
Gives a solution to Lawvere's first open problem.
See also: Lawvere's open problems
Talks: Ph.D. thesis presentation (2026) · UTokyo Logic seminar (2025)
Studies completely connected topoi and gives a site characterization with examples.
Talks: Ph.D. thesis presentation (2026) · UTokyo Logic seminar (2025)
Reinterprets impartial combinatorial games and the Nim-sum using recursive coalgebras.
Talks: CSCAT 2024 (2024) · 7th Japan Combinatorial Game Theory Conference (2023) · Japan Combinatorial Game Theory Mini-Workshops with Urban Larsson (2023)
Gives a preprint solution to one of Lawvere's seven open problems through levels in the topos of symmetric simplicial sets.
Talks: Ph.D. thesis presentation (2026) · UTokyo Logic seminar (2025)
Introduces a topos-theoretic point of view on formal language theory.
Talks: SLACS 2025 (2025) · CT 2025 (2025) · Theoretical Cosynus Seminar (2025) · Séminaires du LIPN (2025) · IRIF Sémantique seminar (2025) · Groupe de travail topossique (2025) · Categories for Automata and Language Theory (2025) · Groupe de travail topossique (2025) · CSCAT 2025 (2025) · CMUP SAL seminar (2025) · Young Automata Theorists Gathering in Japan (2024)
Introduces local state classifiers and uses them to establish an internal parameterization of hyperconnected quotients.
See also: Lawvere's open problems
Talks: Theoretical Cosynus Seminar (2025) · Séminaires du LIPN (2025) · IRIF Sémantique seminar (2025) · Groupe de travail topossique (2025) · Toposes in Mondovì (2024) · Category Theory 2023 (2023) · Australian Category Seminar (2023) · CSCAT 2023 (2023)
Classifies classes of discrete dynamical systems closed under finite limits and small colimits.
See also: Lawvere's open problems
Talks: CT 2024 (2024)
Topoi of automata II: Hyperconnected geometric morphisms and syntactic topoi (PDF), 18 September 2026 — Full outline: 3 main sections and 4 appendices. This abridged version includes Sections 1–3, with Sections 2.4 and 3.3–3.6 and all appendices omitted.
Topos with enough projectives (PDF) — This work is in progress and does not constitute the complete version of the project.
Topoi of automata III: Geometry of Σ-Set (PDF), 20 September 2026 — Draft v0. This abridged version contains the description of points as trees. The sections on infinite words and further topics are omitted.
A space⋊time for Conway's game of life (PDF), 20 September 2026 — This work is in progress and does not constitute the complete version of the project.
Talks: CSCAT 2026 (2026)
Totally disconnected locales and topoi (PDF), 20 September 2026 — Draft v0. This abridged version contains revised Sections 1–2. The section on pushouts and the appendices are omitted.
Talks: UTokyo Logic seminar (2025)
A note on language measurability (PDF), 8 March 2026
Talks: PPL 2026 (2026)
