## Seminar information archive

Seminar information archive ～08/07｜Today's seminar 08/08 | Future seminars 08/09～

### 2021/01/29

#### thesis presentations

9:15-10:30 Online

Feigin-Semikhatov conjecture and its applications

（Feigin-Semikhatov予想とその応用）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**NAKATSUKA Shigenori**(Graduate School of Mathematical Sciences University of Tokyo)Feigin-Semikhatov conjecture and its applications

（Feigin-Semikhatov予想とその応用）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

11:00-12:15 Online

Two-dimensional conformal field theory, current-current deformation and mass formula

（二次元共形場理論のカレントカレント変形と重み公式）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**MORIWAKI Yuto**(Graduate School of Mathematical Sciences University of Tokyo)Two-dimensional conformal field theory, current-current deformation and mass formula

（二次元共形場理論のカレントカレント変形と重み公式）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

9:15-10:30 Online

Spectral analysis on complete anti-de Sitter 3-manifolds

(完備な3次元反ド・ジッター多様体上のスペクトル解析)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**KANNAKA Kazuki**(Graduate School of Mathematical Sciences University of Tokyo)Spectral analysis on complete anti-de Sitter 3-manifolds

(完備な3次元反ド・ジッター多様体上のスペクトル解析)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

11:00-12:15 Online

Bounded cohomology of volume-preserving diffeomorphism groups

(体積保存微分同相群の有界コホモロジー)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**KIMURA Mitsuaki**(Graduate School of Mathematical Sciences University of Tokyo)Bounded cohomology of volume-preserving diffeomorphism groups

(体積保存微分同相群の有界コホモロジー)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

### 2021/01/28

#### Operator Algebra Seminars

16:45-18:15 Online

Finite-index subfactors and rational conformal field theory (English)

[ Reference URL ]

https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

**James Tener**(Australian National Univ.)Finite-index subfactors and rational conformal field theory (English)

[ Reference URL ]

https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

#### thesis presentations

9:15-10:30 Online

On the geometry of projections of von Neumann algebras

（ von Neumann 環の射影束の幾何構造について ）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**MORI Michiya**(Graduate School of Mathematical Sciences University of Tokyo)On the geometry of projections of von Neumann algebras

（ von Neumann 環の射影束の幾何構造について ）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

11:00-12:15 Online

Ray-Singer torsion and the Laplacians of the Rumin complex on lens spaces

(レンズ空間上のRay-Singer捩率とRumin複体のラプラシアン）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**KITAOKA Wataru**(Graduate School of Mathematical Sciences University of Tokyo)Ray-Singer torsion and the Laplacians of the Rumin complex on lens spaces

(レンズ空間上のRay-Singer捩率とRumin複体のラプラシアン）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

13:00-14:15 Online

SCALING LIMITS OF STOCHASTIC HARMONIC CHAINS WITH LONG-RANGE INTERACTIONS

（長距離相関を持つ確率調和振動子鎖に対するスケール極限）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**SUDA Hayate**(Graduate School of Mathematical Sciences University of Tokyo)SCALING LIMITS OF STOCHASTIC HARMONIC CHAINS WITH LONG-RANGE INTERACTIONS

（長距離相関を持つ確率調和振動子鎖に対するスケール極限）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

14:45-16:00 Online

Asymptotic analysis for solutions to semilinear heat equations

(半線形熱方程式の解に対する漸近解析)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**MUKAI Asato**(Graduate School of Mathematical Sciences University of Tokyo)Asymptotic analysis for solutions to semilinear heat equations

(半線形熱方程式の解に対する漸近解析)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

11:00-12:15 Online

Statistical Inference for Stochastic Differential Equations with Jumps:Global Filtering Approach

(ジャンプを含む確率微分方程式に対する統計推測：

大域的フィルターによる方法）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**INATSUGU Haruhiko**(Graduate School of Mathematical Sciences University of Tokyo)Statistical Inference for Stochastic Differential Equations with Jumps:Global Filtering Approach

(ジャンプを含む確率微分方程式に対する統計推測：

大域的フィルターによる方法）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

9:15-10:30 Online

Local in time solvability for reaction-diffusion systems with rapidly growing nonlinear terms

(速く増大する非線形項を持つ連立反応拡散方程式の時間局所可解性)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**SUZUKI Masamitsu**(Graduate School of Mathematical Sciences University of Tokyo)Local in time solvability for reaction-diffusion systems with rapidly growing nonlinear terms

(速く増大する非線形項を持つ連立反応拡散方程式の時間局所可解性)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

11:00-12:15 Online

Finite element analysis for radially symmetric solutions of nonlinear heat equations

(非線形熱方程式の球対称解に対する有限要素解析)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**NAKANISHI Toru**(Graduate School of Mathematical Sciences University of Tokyo)Finite element analysis for radially symmetric solutions of nonlinear heat equations

(非線形熱方程式の球対称解に対する有限要素解析)

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

#### thesis presentations

11:00-12:15 Online

On the epsilon factors of ℓ-adic sheaves on varieties

(多様体上のℓ進層のイプシロン因子について）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

**TAKEUCHI Daichi**(Graduate School of Mathematical Sciences University of Tokyo)On the epsilon factors of ℓ-adic sheaves on varieties

(多様体上のℓ進層のイプシロン因子について）

[ Reference URL ]

https://forms.gle/bdsntP4pZ4TMaehF9

### 2021/01/25

#### Seminar on Geometric Complex Analysis

10:30-12:00 Online

Existence of a complete holomorphic vector field via the Kähler-Einstein metric

https://zoom.us/meeting/register/tJ0vcu2rrDIqG9Rv5AT0Mpi37urIkJ1IRldB

**Young-Jun Choi**(Pusan National University)Existence of a complete holomorphic vector field via the Kähler-Einstein metric

[ Abstract ]

A fundamental problem in Several Complex Variables is to classify bounded pseudoconvex domains in the complex Euclidean space with a noncompact automorphism group, especially with a compact quotient. In the results of Wong-Rosay and Frankel, they make use of the "Scaling method'' for obtaining an 1-parameter family of automorphisms, which generates a holomorphic vector field.

In this talk, we discuss the existence of a nowhere vanishing complete holomorphic vector filed on a strongly pseudoconvex manifold admtting a negatively curved Kähler-Einstein metric and discrete sequence of automorphisms by introducing the scaling method on potentials of the Kähler-Einstein metric.

[ Reference URL ]A fundamental problem in Several Complex Variables is to classify bounded pseudoconvex domains in the complex Euclidean space with a noncompact automorphism group, especially with a compact quotient. In the results of Wong-Rosay and Frankel, they make use of the "Scaling method'' for obtaining an 1-parameter family of automorphisms, which generates a holomorphic vector field.

In this talk, we discuss the existence of a nowhere vanishing complete holomorphic vector filed on a strongly pseudoconvex manifold admtting a negatively curved Kähler-Einstein metric and discrete sequence of automorphisms by introducing the scaling method on potentials of the Kähler-Einstein metric.

https://zoom.us/meeting/register/tJ0vcu2rrDIqG9Rv5AT0Mpi37urIkJ1IRldB

### 2021/01/22

#### Colloquium

15:30-16:30 Online

Please register at the link below to attend this online colloquium

Convolution algebras and a new proof of Kazhdan-Lusztig formula (JAPANESE)

[ Reference URL ]

https://forms.gle/AAVzoCGPyLmzDJHf7

Please register at the link below to attend this online colloquium

**Hiraku Nakajima**(Kavli IPMU)Convolution algebras and a new proof of Kazhdan-Lusztig formula (JAPANESE)

[ Reference URL ]

https://forms.gle/AAVzoCGPyLmzDJHf7

### 2021/01/21

#### Information Mathematics Seminar

16:50-18:35 Online

Topological quantum error-correcting codes and fault-tolerant quantum computing (Japanese)

https://docs.google.com/forms/d/1yIKNrwSLsdYt_rivZI8JxhIu3kWtJua5hG8nV5FYbCk/

**Yasunari Suzuki**(NTT)Topological quantum error-correcting codes and fault-tolerant quantum computing (Japanese)

[ Abstract ]

Explanation on topological quantum error-correcting codes and fault-tolerant quantum computing

[ Reference URL ]Explanation on topological quantum error-correcting codes and fault-tolerant quantum computing

https://docs.google.com/forms/d/1yIKNrwSLsdYt_rivZI8JxhIu3kWtJua5hG8nV5FYbCk/

#### Tokyo-Nagoya Algebra Seminar

17:00-18:30 Online

Please see the URL below for details on the online seminar.

Based modules over the i-quantum group of type AI (Japanese)

http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html

Please see the URL below for details on the online seminar.

**Hideya Watanabe**(Kyoto University)Based modules over the i-quantum group of type AI (Japanese)

[ Abstract ]

In recent years, i-quantum groups are intensively studied because of their importance in various branches of mathematics and physics. Although i-quantum groups are thought of as generalizations of Drinfeld-Jimbo quantum groups, their representation theory is much more difficult than that of quantum groups. In this talk, I will focus on the i-quantum group of type AI. It is a non-standard quantization of the special orthogonal Lie algebra so_n. I will report my recent research on based modules, which are modules equipped with distinguished bases, called the i-canonical bases. The first main result is a new combinatorial formula describing the branching rule from sl_n to so_n. The second one is the irreducibility of cell modules associated with the i-canonical bases.

[ Reference URL ]In recent years, i-quantum groups are intensively studied because of their importance in various branches of mathematics and physics. Although i-quantum groups are thought of as generalizations of Drinfeld-Jimbo quantum groups, their representation theory is much more difficult than that of quantum groups. In this talk, I will focus on the i-quantum group of type AI. It is a non-standard quantization of the special orthogonal Lie algebra so_n. I will report my recent research on based modules, which are modules equipped with distinguished bases, called the i-canonical bases. The first main result is a new combinatorial formula describing the branching rule from sl_n to so_n. The second one is the irreducibility of cell modules associated with the i-canonical bases.

http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html

#### Operator Algebra Seminars

16:45-18:15 Online

On induction along a homomorphism of compact quantum groups

[ Reference URL ]

https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

**Kan Kitamura**(Univ. Tokyo)On induction along a homomorphism of compact quantum groups

[ Reference URL ]

https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

### 2021/01/20

#### Number Theory Seminar

17:00-18:00 Online

Overconvergent Lubin-Tate $(\varphi, \Gamma)$-modules for different uniformizers (Japanese)

**Yuta Saito**(University of Tokyo)Overconvergent Lubin-Tate $(\varphi, \Gamma)$-modules for different uniformizers (Japanese)

[ Abstract ]

$(\varphi, \Gamma)$-modules are used for investigating p-adic Galois representations, which has an important role in constructing the p-adic local Langlands correspondence for GL_2(Q_p). When we try to construct the p-adic local correspondence for GL_2(F) for a general local field F, we want more useful and more suitable $(\varphi, \Gamma)$-modules. Lubin-Tate $(\varphi, \Gamma)$-modules are the candidates for such $(\varphi, \Gamma)$-modules. Lubin-Tate extensions are used for defining Lubin-Tate $(\varphi, \Gamma)$-modules. However, these extensions depend on the choice of uniformizers and the behavior of Lubin-Tate $(\varphi, \Gamma)$-modules for different uniformizers has not been discussed so much. We focus on overconvergency and discuss the coincidence for 2-dimensional triangulable $(\varphi, \Gamma)$-modules for different uniformizers.

$(\varphi, \Gamma)$-modules are used for investigating p-adic Galois representations, which has an important role in constructing the p-adic local Langlands correspondence for GL_2(Q_p). When we try to construct the p-adic local correspondence for GL_2(F) for a general local field F, we want more useful and more suitable $(\varphi, \Gamma)$-modules. Lubin-Tate $(\varphi, \Gamma)$-modules are the candidates for such $(\varphi, \Gamma)$-modules. Lubin-Tate extensions are used for defining Lubin-Tate $(\varphi, \Gamma)$-modules. However, these extensions depend on the choice of uniformizers and the behavior of Lubin-Tate $(\varphi, \Gamma)$-modules for different uniformizers has not been discussed so much. We focus on overconvergency and discuss the coincidence for 2-dimensional triangulable $(\varphi, \Gamma)$-modules for different uniformizers.

### 2021/01/18

#### Seminar on Geometric Complex Analysis

10:30-12:00 Online

The hydrodynamic period matrices and closings of an open Riemann surface of finite genus

https://zoom.us/meeting/register/tJ0vcu2rrDIqG9Rv5AT0Mpi37urIkJ1IRldB

**HAMANO Sachiko**(Osaka City University)The hydrodynamic period matrices and closings of an open Riemann surface of finite genus

[ Abstract ]

A closing of an open Riemann srface $R$ of finite genus is a shorter name of a closed Riemann surface of the same genus into which $R$ can be embedded by a homology type preserving conformal mapping. We observe the Riemann period matrices of all closings of $R$ in the Siegel upper half space. It is known that every hydrodynamic differential on $R$ yields a closing of $R$ called a hydrodynamic closing. (A hydrodynamic differential is a holomorphic which describes a steady flow on $R$ of an ideal fluid.) We study the period matices induced by hydrodynamic closings of $R$. This is a joint work with Masakazu Shiba.

[ Reference URL ]A closing of an open Riemann srface $R$ of finite genus is a shorter name of a closed Riemann surface of the same genus into which $R$ can be embedded by a homology type preserving conformal mapping. We observe the Riemann period matrices of all closings of $R$ in the Siegel upper half space. It is known that every hydrodynamic differential on $R$ yields a closing of $R$ called a hydrodynamic closing. (A hydrodynamic differential is a holomorphic which describes a steady flow on $R$ of an ideal fluid.) We study the period matices induced by hydrodynamic closings of $R$. This is a joint work with Masakazu Shiba.

https://zoom.us/meeting/register/tJ0vcu2rrDIqG9Rv5AT0Mpi37urIkJ1IRldB

### 2021/01/14

#### Information Mathematics Seminar

16:50-18:35 Online

Introduction to quantum computation and quantum error-correcting codes (Japanese)

https://docs.google.com/forms/d/1yIKNrwSLsdYt_rivZI8JxhIu3kWtJua5hG8nV5FYbCk/

**Yasunari Suzuki**(NTT)Introduction to quantum computation and quantum error-correcting codes (Japanese)

[ Abstract ]

Introduction to quantum computation and quantum error-correcting codes

[ Reference URL ]Introduction to quantum computation and quantum error-correcting codes

https://docs.google.com/forms/d/1yIKNrwSLsdYt_rivZI8JxhIu3kWtJua5hG8nV5FYbCk/

#### Tokyo-Nagoya Algebra Seminar

16:00-17:30 Online

Please see the URL below for details on the online seminar.

$(-2)$ blow-up formula (Japanese)

[ Reference URL ]

http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html

Please see the URL below for details on the online seminar.

**Ryo Ohkawa**(Kobe University)$(-2)$ blow-up formula (Japanese)

[ Reference URL ]

http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html

#### Operator Algebra Seminars

16:45-18:15 Online

The Green-Tao theorem for number fields

[ Reference URL ]

https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

**Masato Mimura**(Tohoku Univ.)The Green-Tao theorem for number fields

[ Reference URL ]

https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm

#### Mathematical Biology Seminar

15:00-16:00 Room # (Graduate School of Math. Sci. Bldg.)

Estimation of the evacuation effect from Wuhan, China, during COVID-19 outbreak

**Yusuke Asai**(National Center for Global Health and Medicine)Estimation of the evacuation effect from Wuhan, China, during COVID-19 outbreak

### 2021/01/13

#### Discrete mathematical modelling seminar

17:00-18:00 Online

This seminar will be held using Zoom. If you wish to participate, please contact R. Willox by email.

Tetrahedron and 3D reflection equation from PBW bases of the nilpotent subalgebra of quantum superalgebras (in Japanese)

This seminar will be held using Zoom. If you wish to participate, please contact R. Willox by email.

**Akihito Yoneyama**(Institute of Physics, Graduate School of Arts and Sciences, the University of Tokyo)Tetrahedron and 3D reflection equation from PBW bases of the nilpotent subalgebra of quantum superalgebras (in Japanese)

[ Abstract ]

We study transition matrices of PBW bases of the nilpotent subalgebra of quantum superalgebras associated with all possible Dynkin diagrams of type A and B in the case of rank 2 and 3, and examine relationships with three-dimensional (3D) integrability. We obtain new solutions to the Zamolodchikov tetrahedron equation via type A and the 3D reflection equation via type B, where the latter equation was proposed by Isaev and Kulish as a 3D analog of the reflection equation of Cherednik. As a by-product of our approach, the Bazhanov-Sergeev solution to the Zamolodchikov tetrahedron equation is characterized as the transition matrix for a particular case of type A, which clarifies an algebraic origin of it. Our work is inspired by the recent developments connecting transition matrices for quantum non-super algebras with intertwiners of irreducible representations of quantum coordinate rings. We also discuss the crystal limit of transition matrices, which gives a super analog of transition maps of Lusztig's parametrizations of the canonical basis.

https://arxiv.org/abs/2012.13385

We study transition matrices of PBW bases of the nilpotent subalgebra of quantum superalgebras associated with all possible Dynkin diagrams of type A and B in the case of rank 2 and 3, and examine relationships with three-dimensional (3D) integrability. We obtain new solutions to the Zamolodchikov tetrahedron equation via type A and the 3D reflection equation via type B, where the latter equation was proposed by Isaev and Kulish as a 3D analog of the reflection equation of Cherednik. As a by-product of our approach, the Bazhanov-Sergeev solution to the Zamolodchikov tetrahedron equation is characterized as the transition matrix for a particular case of type A, which clarifies an algebraic origin of it. Our work is inspired by the recent developments connecting transition matrices for quantum non-super algebras with intertwiners of irreducible representations of quantum coordinate rings. We also discuss the crystal limit of transition matrices, which gives a super analog of transition maps of Lusztig's parametrizations of the canonical basis.

https://arxiv.org/abs/2012.13385

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