I am Ryoya Arimoto, a researcher at RIMS, Kyoto University.
Research interest: Operator algebras, Totally disconnected locally compact groups, Thompson groups
e-mail: arimoto[at]kurims.kyoto-u.ac.jp / ryoya.arimoto[at]gmail.com
CV
1997 Born in Nara, Japan
March 2020 Bachelor of Science, Kyoto University
March 2022 Master of Science, Kyoto University
Advisor: Professor Narutaka Ozawa
March 2025 Doctor of Science, Kyoto University
Advisor: Professor Narutaka Ozawa
April 2025-- Researcher at RIMS, Kyoto university
Publications
On the type of the von Neumann algebra of an open subgroup of the Neretin group.
Proc. Amer. Math. Soc. Ser. B 9 (2022), 311–316. doi: https://doi.org/10.1090/bproc/133
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries.
J. Funct. Anal. 288.3 (2025), 110732. doi: https://doi.org/10.1016/j.jfa.2024.110732
Topological full groups arising from Cuntz and Cuntz-Toeplitz algebras and their crossed products. (with T. Sogabe)
Preprint. arXiv: 2504.05145
Non-strong ergodicity of canonical actions of the Thompson groups.
Preprint. arXiv: 2510.13309
Talks
C*-simplicity. Junior Meeting on Functional Analysis, online, 22 September 2021.
On the type of the von Neumann algebra of an open subgroup of the Neretin group. Kyoto Operator Algebra Seminar, RIMS, 12 April 2022.
Properties of the Neretin group. Junior Meeting on Functional Analysis, Kyoto, 31 August 2022.
On the type of the von Neumann algebra of an open subgroup of the Neretin group. Recent Developments in Operator Algebras, RIMS, 6 September 2022.
On the type of the von Neumann algebra of an open subgroup of the Neretin group. Operator Algebra Seminars of the University of Tokyo, the University of Tokyo, 8 November 2022.
On the type of the von Neumann algebra of an open subgroup of the Neretin group. The 8th KTGU Mathematics Workshop for Young Researchers, Kyoto University, 31 January 2023.
On the Neretin group and its distinguished open subgroup. The 19th Mathematics Conference for Young Researchers, Hokkaido University, 8 March 2023. technical report (in Japanese)
On the type of the von Neumann algebra of an open subgroup of the Neretin group. Annual Meeting of the Mathematical Society of Japan, Chuo University, 17 March 2023.
On the type of the von Neumann algebra of an open subgroup of the Neretin group. YMC*A 2023, KU Leuven, 11 August 2023. slide
Groups acting on trees with almost prescribed local action (after Le Boudec). Junior Meeting on Functional Analysis, Kyoto, 6 September 2023.
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries. Ideal Structure of C*-algebras from Dynamics and Groups, Friedrich-Alexander-Universität Erlangen-Nürnberg, 9 April 2024.
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries. Kyoto Operator Algebra Seminar, 26 April 2024.
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries. Operator Algebra Seminars of the University of Tokyo, the University of Tokyo, 4 June 2024.
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries. The Mathematical Society of Japan Autumn Meeting 2024, Osaka University, 4 September 2024.
Simplicity of crossed products of the actions of groups on their boundaries. Junior Meeting on Functional Analysis, Hokkaido University, 18 September 2024.
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries. Group Operator Algebras: Classification, Structure and Rigidity, Banff International Research Station, 26 September 2024.
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries. The 8th Workshop on Geometric Group Theory, Kagoshima University, 11 November 2024.
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries. The 1st MMS Workshop for Young Researchers, Kyoto University,20 November 2024.
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries. Analysis Seminar, University of Waterloo, 12 December 2024.
Simplicity of crossed products of the actions of totally disconnected locally compact groups on their boundaries. Group Theory Around Operator Algebras, RIMS, 24 January 2025.
Topological full groups arising from Cuntz and Cuntz-Toeplitz algebras and their crossed products. Kyoto Operator Algebra Seminar, RIMS, 18 July 2025.
Topological full group arising from Cuntz--Toeplitz algebras. World of GroupCraft V, online, 1 September 2025.
Fellowships
April 2022-March 2023 Kyoto University Graduate Division Fellow
April 2023- March 2025 Japan Society for the Promotion of Science Research Fellowship for Young Scientists (DC2)
Schedule
7 September-9 September Recent Developments in Operator Algebras, online
17 September Junior Meeting on Functional Analysis, online
1 February-3 February Operator Algebras and Quantum Dynamics, online
20 September-23 September Junior Meeting on Functional Analysis, online
27 September-28 September Recent Developments in Operator Algebras, online
24 January-26 January Symmetry and amenability in operator algebras, RIMS
30 August-2 September Junior Meeting on Functional Analysis, Kyoto
5 September-7 September Recent Developments in Operator Algebras, RIMS
10 December-12 December Operator theory and operator algebras, Osaka Kyoiku University
23 January-25 January Relations between Group Actions and Mathematical Physics in Operator Algebras, RIMS
30 January-31 January The 8th KTGU Mathematics Workshop for Young Researchers, Kyoto University
6 March-9 March The 19th Mathematics Conference for Young Researchers, Hokkaido University
15 March-18March Annual Meeting of the Mathematical Society of Japan, Chuo University
24 July-28 July Operator Algebras and Mathematical Physics (Yasu Festa 60), the University of Tokyo
7 August-11 August YMC*A, KU Leuven
5 September-8 September Junior Meeting on Functional Analysis, Kyoto Institute of Technology
11 September-15 September Totally disconnected locally compact groups from a geometric perspective, University of Münster
23 November-25 November Operator theory and operator algebras, Kyushu University
27 November-28 November The 7th Workshop on Geometric Group Theory, Niigata
22 January-24 January Operator algebras and symmetries, RIMS
17 March-20 March Annual Meeting of the Mathematical Society of Japan, Osaka Metropolitan University
8 April-12 April Ideal Structure of C*-algebras from Dynamics and Groups, Friedrich-Alexander-Universität Erlangen-Nürnberg
11 September-13 September Recent Developments in Operator Algebras, RIMS
17 September-20 September Junior Meeting on Functional Analysis, Hokkaido University
23 September-27 September Group Operator Algebras: Classification, Structure and Rigidity, Banff International Research Station
11 November-12 November The 8th Workshop on Geometric Group Theory, Kagoshima University
20 November-21 November The 1st MMS Workshop for Young Researchers, Kyoto University
1 December-21 December University of Waterloo
22 January-24 January Group Theory Around Operator Algebras, RIMS