Assistant Professor, Kyoto Institute of Technology

e-mail: takeishi at kit.ac.jp

Reserch interest: Operator algebras from number theory (Bost-Connes systems, semigroup C*-algebras arising from number theory), KMS-states, groupoid C*-algebras.

Supported by JSPS KAKENHI Grant Number JP19K14551 (2019-2023)

Previous KAKENHI

- October 2021 - , Mathematical Analysis and its Applications (Thu. 10:30-12:00).
- April 2021 - , Seminar on analysis (Thu. 16:10-17:40), with Takuya Mine.
- April 2021 - , Exercises in Mathematics I (Thu. 10:30-12:00).
- April 2021 - , Basic Calculus I (Thu. 8:50-10:20).
- April 2021 - , Studies in Applied Analysis (Mon. 12:50-14:20), with Takuya Mine, Yasuki Isozaki.
- April 2021 - , Mathematical Sciences I (Mon. 16:10-17:40), with Yusuke Okuyama.

- T. Takeishi,
*On Nuclearity of C*-algebras of Fell Bundles over Étale Groupoids*, Publications of the Research Institute for Mathematical Sciences**50**, no.2, 251-268. (2014) published version arXiv version - T. Takeishi,
*Irreducible Representations of Bost-Connes systems*, Journal of Noncommutative Geometry**10**, no. 3, 889-906. (2016) published version arXiv version

(**Note**: For arXiv version, the current version is 2. Several mistakes of notations are revised and section numbers are changed.) - T. Takeishi,
*Bost-Connes systems for local fields of characteristic zero*, International Mathematics Research Notices**IMRN 2018**, no. 7, 2052-2069 (2018). published version arXiv version - T. Takeishi,
*Primitive ideals and K-theoretic approach to Bost-Connes systems*, Advances in Mathematics**302**, 1069-1079. (2016) published version arXiv version

(**Note**: For arXiv version, the current version is 2. Proposition 3.6, Remark 3.13, and several minor revisions are added.) - Y. Kubota and T. Takeishi,
*Reconstructing the Bost--Connes semigroup actions from K-theory*, Advances in Mathematics**366**(2020) published version arXiv version

(Page number will be added later.) - C. Bruce, M. Laca and T. Takeishi,
*Partition functions as C*-dynamical invariants and actions of congruence monoids*, Communications in Mathematical Physics**382**, no.2, 1165–1203. (2021) published version arXiv:1911.00793

(**Note**: For arXiv version, the current version is 2. ) - C. Bruce and T. Takeishi,
*C*-dynamical invariants and Toeplitz algebras of graphs*(2021), arXiv:2103.02816 - T. Takeishi,
*Limits of KMS states on Toeplitz algebras of finite graphs*(2021), arXiv:2108.08431

- 武石拓也，作用素環論と数論，「数理科学」2019年12月号掲載

- On Nuclearity of C*-algebras of Fell Bundles over Étale Groupoids, Operator Algebra Seminar, Tokyo, April, 2013
- On Nuclearity of C*-algebras of Fell Bundles over Étale Groupoids, Recent Developments in Operator Algebras, Kyoto, September, 2013
- On Class Field Theory, Conference of Functional Analysis, Kusatsu, September, 2013
- On Nuclearity of C*-algebras of Fell Bundles over Étale Groupoids, MSJ Autumn Meeting 2013, Ehime, September, 2013
- Bost-Connes system for local fields of characteristic zero, C*-algebra seminar, Oslo, January, 2014
- Bost-Connes system for local fields of characteristic zero, Operator Algebra Seminar, Tokyo, April, 2014
- Bost-Connes system for local fields of characteristic zero, ICM Satellite Conference on Operator Algebra and Applications, Korea, August, 2014
- On Bost-Connes Systems, Conference of Functional Analysis, Gifu, August, 2014
- Bost-Connes system for local fields of characteristic zero, MSJ Autumn Meeting 2014, Hiroshima, September, 2014
- Bost-Connes system for local fields of characteristic zero,
The Second China-Japan Conference on Noncommutative Geometry and K-Theory, Okinawa, October, 2014

Slides - Irreducible Representations of Bost-Connes systems, Number theory and non-commutative geometry, Bonn, November, 2014

Video on Youtube - Irreducible Representations of Bost-Connes systems, Workshop on Operator Theory and Operator Algebras, Tokyo, December, 2014
- Irreducible Representations of Bost-Connes systems, Kyoto Operator Algebra Seminar, Kyoto, March, 2015
- Irreducible Representations of Bost-Connes systems, Oberseminar, Münster, June, 2015
- Irreducible Representations of Bost-Connes systems, Oberwolfach, June, 2015
- Primitive Ideals of Bost-Connes C*-algebras, Geometry and Analysis seminar, London, September, 2015
- On the classification problem of Bost-Connes systems, Operator Algebra Seminar, Copenhagen, October, 2015
- Primitive ideals and K-theoretic approach to Bost-Connes systems, Münster, December, 2015
- Primitive ideals and K-theoretic approach to Bost-Connes systems, Victoria, March, 2016
- Primitive ideals and K-theoretic approach to Bost-Connes systems, Kyoto Operator Algebra Seminar, Kyoto, July, 2016
- On the condition C^*_(G)=C^*_r(G) for étale groupoids (after R. Willett), Conference of Functional Analysis, Kusatsu, August, 2016
- Primitive ideals and K-theoretic approach to Bost-Connes systems, Recent Developments in Operator Algebras, Kyoto, September, 2016
- Primitive ideals and K-theoretic approach to Bost-Connes systems, MSJ Autumn Meeting 2016, Osaka, September, 2013
- On the classification of Bost-Connes C*-algebras, Geometry and Analysis seminar, London, January, 2017
- On the classification problem of Bost-Connes systems, Analysis Seminar, Sapporo, 2017
- Basics of K-theory, Conference of Functional Analysis, Nara, August, 2017
- Reconstructing the Bost-Connes semigroup actions from K-theory, Recent Developments in Operator Algebras, Kyoto, September, 2017
- Reconstructing the Bost-Connes semigroup actions from K-theory, Facets of Irreversibility: Inverse Semigroups, Groupoids, and Operator Algebras, Oslo, Norway, December, 2017
- Reconstructing the Bost-Connes semigroup actions from K-theory, Mathematical study on topological phases, RIMS, Kyoto, Japan, January 2018
- Reconstructing the Bost-Connes semigroup actions from K-theory, MSJ Spring Meeting 2018, Tokyo, Japan, March, 2018
- Reconstructing the Bost-Connes semigroup actions from K-theory. I, Operator theory seminar, Victoria, Canada, September, 2018
- Reconstructing the Bost-Connes semigroup actions from K-theory. II, Operator theory seminar, Victoria, Canada, September, 2018
- Reconstructing the Bost-Connes semigroup actions from K-theory, Geometry and Analysis Seminar, London, UK, October, 2018
- Reconstructing the Bost-Connes semigroup actions from K-theory. I, Workshop on Operator Theory and Operator Algebras, Shizuoka, December, 2018
- Reconstructing the Bost-Connes semigroup actions from K-theory. II, Workshop on Operator Theory and Operator Algebras, Shizuoka, December, 2018
- Reconstructing the Bost-Connes semigroup actions from K-theory, Young mathematicians workshop on algebraic, geometric, and analytic aspects of K theory and vector bundles, Okinawa, August, 2019
- C*-dynamical invariants for actions of congruence monoids (in preparation), Operator theory seminar, Victoria, Canada, September, 2019
- Partition functions as C*-dynamical invariants and actions of congruence monoids, Kyoto Operator Algebra Seminar, Kyoto, 2019
- Partition functions as C*-dynamical invariants and actions of congruence monoids, 作用素環の分類理論における新展開, RIMS, Kyoto, Japan, 2020
- Partition functions as C*-dynamical invariants and actions of congruence monoids, MSJ Spring Meeting 2020, Tokyo, March, 2020

(This conference is canceled, but this talk shall be deemed held. See here (Japanese)) - Partition functions as C*-dynamical invariants and actions of congruence monoids, Tokyo-Kyoto Operator Algebra Seminar, Online, May, 2020
- Operator Algebras and Number Theory, Conference of Functional Analysis, Online, September, 2020
- Partition functions as C*-dynamical invariants and actions of congruence monoids, CMS Winter Meeting 2020, Online (Canada), December, 2020
- Partition functions as C*-dynamical invariants and actions of congruence monoids, 作用素環と量子力学系, Online (RIMS Kyoto), February, 2021
- C*-dynamical invariants and Toeplitz algebras of graphs (part 2 of 2), Operator Algebra and Noncommutative Geometry seminar, Online (Wollongong, Australia), March, 2021
- KMS states of Toeplitz algebras of graphs, Tokyo-Kyoto Operator Algebra Seminar, Online, June, 2021
- KMS states of Toeplitz algebras of graphs, 第60回実函数論・函数解析学合同シンポジウム, Online, September, 2021

- Irreducible Representations of Bost-Connes systems, Future directions for non-commutative geometry, Bonn, December, 2014

March 2011 | Bachelor of Sciences, University of Tokyo |
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November 2012 - March 2016 | FMSP fellow |

March 2013 | Master of Mathematical Sciences, the University of Tokyo (Supervisor: Yasuyuki Kawahigashi) |

April 2013 - March 2016 | JSPS Fellow (DC1) |

March 2016 | Ph.D. of Mathematical Sciences, the University of Tokyo (Supervisor: Yasuyuki Kawahigashi) |

April 2016 - March 2017 | Program-Specific Researcher (Fujiwara's grant), Department of Mathematics, Kyoto University |

April 2017 - March 2018 | Researcher (part-time), Research Institute for Mathematical Sciences, Kyoto University |

April 2017 - August 2017 | Lecturer (part-time), Institute for Liberal Arts and Sciences, Kyoto University |

April 2018 - | Assistant Professor, Kyoto Institute of Technology |