## Seminar information archive

Seminar information archive ～08/18｜Today's seminar 08/19 | Future seminars 08/20～

#### thesis presentations

14:15-15:30 Room #118 (Graduate School of Math. Sci. Bldg.)

On The Discrete Logarithm Problem in Finite Fields(有限体上の離散対数問題について)

(JAPANESE)

**ZHANG Qizhi**(Graduate School of Mathematical Sciences University of Tokyo)On The Discrete Logarithm Problem in Finite Fields(有限体上の離散対数問題について)

(JAPANESE)

#### thesis presentations

15:45-17:00 Room #118 (Graduate School of Math. Sci. Bldg.)

Rationality of the moduli spaces of 2-elementary K3 surfaces(対合付きK3曲面のモジュライの有理性)

(JAPANESE)

**Syohei MA**(Graduate School of Mathematical Sciences University of Tokyo)Rationality of the moduli spaces of 2-elementary K3 surfaces(対合付きK3曲面のモジュライの有理性)

(JAPANESE)

#### thesis presentations

09:45-11:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Determining nodes for semilinear parabolic evolution equations in Banach spaces(バナッハ空間上の半線型放物型発展方程式に対する確定節点)

(JAPANESE)

**Ryohei KAKIZAWA**(Graduate School of Mathematical Sciences University of Tokyo)Determining nodes for semilinear parabolic evolution equations in Banach spaces(バナッハ空間上の半線型放物型発展方程式に対する確定節点)

(JAPANESE)

#### thesis presentations

11:00-12:15 Room #128 (Graduate School of Math. Sci. Bldg.)

Polynomial relations for q-characters via ODM/IM correspondence(ODE/IM対応を用いたq指標の多項式関係)

(JAPANESE)

**SUN JuanJuan**(Graduate School of Mathematical Sciences University of Tokyo)Polynomial relations for q-characters via ODM/IM correspondence(ODE/IM対応を用いたq指標の多項式関係)

(JAPANESE)

#### thesis presentations

13:00-14:15 Room #128 (Graduate School of Math. Sci. Bldg.)

Entire curves in projective algebraic varieties(射影代数多様体内の正則曲線について)

(JAPANESE)

**Yusaku CHIBA**(Graduaate School of Mathematical Sciences University of Tokyo)Entire curves in projective algebraic varieties(射影代数多様体内の正則曲線について)

(JAPANESE)

### 2012/02/01

#### PDE Real Analysis Seminar

10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)

Energetic variational approach: generalized diffusion, stochastic differential equations and optimal transport (ENGLISH)

**Chun Liu**(University of Tokyo / Penn State University)Energetic variational approach: generalized diffusion, stochastic differential equations and optimal transport (ENGLISH)

[ Abstract ]

In the talk, I will explore the general framework of energetic variational approaches, which are the direct consequences of classical isothermal thermodynamics, and their particular applications in generalized diffusion problems. In particular, we reveal the roles of different stochastic integrations (Ito's form, Stratonovich's form and other possible forms) and the Wasserstein metric and the procedure of optimal transport in the context of general framework of theories of linear responses.

In the talk, I will explore the general framework of energetic variational approaches, which are the direct consequences of classical isothermal thermodynamics, and their particular applications in generalized diffusion problems. In particular, we reveal the roles of different stochastic integrations (Ito's form, Stratonovich's form and other possible forms) and the Wasserstein metric and the procedure of optimal transport in the context of general framework of theories of linear responses.

### 2012/01/31

#### Tuesday Seminar of Analysis

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Obstacle problems in unbounded domains (ENGLISH)

**Michel Chipot**(University of Zurich)Obstacle problems in unbounded domains (ENGLISH)

[ Abstract ]

We will present a formulation of obstacle problems in unbounded

domains when the energy method does not work, i.e. whenthe force does not belong to H^{-1}.

We will present a formulation of obstacle problems in unbounded

domains when the energy method does not work, i.e. whenthe force does not belong to H^{-1}.

### 2012/01/30

#### Algebraic Geometry Seminar

15:30-17:00 Room #122 (Graduate School of Math. Sci. Bldg.)

On varieties of globally F-regular type (JAPANESE)

**Yoshinori Gongyo**(University of Tokyo)On varieties of globally F-regular type (JAPANESE)

[ Abstract ]

I will talk about recent topics on varieties of globally F-regular type.

I will talk about recent topics on varieties of globally F-regular type.

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Differential equations as embedding obstructions and vanishing theorems (ENGLISH)

**Damian Brotbek**(University of Tokyo)Differential equations as embedding obstructions and vanishing theorems (ENGLISH)

[ Abstract ]

Given a smooth projective variety $X$ it is natural to wonder what is the smallest integer $N$ such that one can embed $X$ into $\mathbf{P}^N$. In this talk I will first recall what can be said for any smooth projective variety, then I will explain how the existence of some particular differential equations on $X$ yields obstructions to the existence of some projective embeddings.

Given a smooth projective variety $X$ it is natural to wonder what is the smallest integer $N$ such that one can embed $X$ into $\mathbf{P}^N$. In this talk I will first recall what can be said for any smooth projective variety, then I will explain how the existence of some particular differential equations on $X$ yields obstructions to the existence of some projective embeddings.

### 2012/01/27

#### Colloquium

16:30-17:30 Room #123 (Graduate School of Math. Sci. Bldg.)

On Topological Blow-up (JAPANESE)

**Taro YOSHINO**(Graduate School of Mathematical Sciences, University of Tokyo)On Topological Blow-up (JAPANESE)

[ Abstract ]

Topological blow-up is a method to understand non-Hausdorff spaces. We define an obstruction to Hausdorffness, and call it crack. By `blowing up' the points in crack, we can obtain better space.

Topological blow-up is a method to understand non-Hausdorff spaces. We define an obstruction to Hausdorffness, and call it crack. By `blowing up' the points in crack, we can obtain better space.

### 2012/01/26

#### Operator Algebra Seminars

16:30-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)

The transverse fundamental class of linear foliations

on torus bundles over the circle (ENGLISH)

**Catherine Oikonomides**(Univ. Tokyo)The transverse fundamental class of linear foliations

on torus bundles over the circle (ENGLISH)

### 2012/01/24

#### Numerical Analysis Seminar

16:30-18:00 Room #002 (Graduate School of Math. Sci. Bldg.)

Phasefield model for crack simulation and its application (JAPANESE)

[ Reference URL ]

http://www.infsup.jp/utnas/

**Takeshi Takaishi**(Hiroshima Kokusai Gakuin University)Phasefield model for crack simulation and its application (JAPANESE)

[ Reference URL ]

http://www.infsup.jp/utnas/

### 2012/01/23

#### Algebraic Geometry Seminar

15:30-17:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Sigularities and Kodaira dimension of the moduli of stable sheaves on Enriques surfaces (JAPANESE)

**Kimiko Yamada**(Okayama university)Sigularities and Kodaira dimension of the moduli of stable sheaves on Enriques surfaces (JAPANESE)

[ Abstract ]

We shall estimate singularities of moduli of stable sheaves on Enriques/hyper-elliptic surfaces via the Kuranishi theory, consider when its singularities are canonical, and calculate its Kodaira dimension.

We shall estimate singularities of moduli of stable sheaves on Enriques/hyper-elliptic surfaces via the Kuranishi theory, consider when its singularities are canonical, and calculate its Kodaira dimension.

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Twistor correspondence for R-invariant indefinite self-dual metric on R^4 (JAPANESE)

**Fuminori Nakata**(Tokyo University of Science)Twistor correspondence for R-invariant indefinite self-dual metric on R^4 (JAPANESE)

#### GCOE lecture series

13:30-15:00 Room #122 (Graduate School of Math. Sci. Bldg.)

TBA(中止になりました) (ENGLISH)

**Mihai Paun**(Institut Élie Cartan and KIAS)TBA(中止になりました) (ENGLISH)

### 2012/01/20

#### Kavli IPMU Komaba Seminar

14:45-16:15 Room #056 (Graduate School of Math. Sci. Bldg.)

Refined holomorphic anomaly equations (ENGLISH)

**Albrecht Klemm**(The University of Bonn)Refined holomorphic anomaly equations (ENGLISH)

[ Abstract ]

We propose a derivation of refined holomophic

anomaly equation from the word-sheet point of

view and discuss the interpretation of the

refined BPS invariants for local Calabi-Yau

spaces.

We propose a derivation of refined holomophic

anomaly equation from the word-sheet point of

view and discuss the interpretation of the

refined BPS invariants for local Calabi-Yau

spaces.

### 2012/01/19

#### Applied Analysis

16:00-17:30 Room #128 (Graduate School of Math. Sci. Bldg.)

Undercompressible shocks and moving phase boundaries

(ENGLISH)

**Philippe G. LeFloch**(Univ. Paris 6 / CNRS)Undercompressible shocks and moving phase boundaries

(ENGLISH)

[ Abstract ]

I will present a study of traveling wave solutions to third-order, diffusive-dispersive equations, which arise in the modeling of complex fluid flows and represent regularization-sensitive wave patterns, especially undercompressive shock waves and moving phase boundaries. The qualitative properties of these (possibly oscillatory) traveling waves are well-understood in terms of the so-called kinetic relation, and this has led to a new theory of (nonclassical) solutions to nonlinear hyperbolic systems. Relevant papers are available at the link: www.philippelefloch.org.

I will present a study of traveling wave solutions to third-order, diffusive-dispersive equations, which arise in the modeling of complex fluid flows and represent regularization-sensitive wave patterns, especially undercompressive shock waves and moving phase boundaries. The qualitative properties of these (possibly oscillatory) traveling waves are well-understood in terms of the so-called kinetic relation, and this has led to a new theory of (nonclassical) solutions to nonlinear hyperbolic systems. Relevant papers are available at the link: www.philippelefloch.org.

### 2012/01/18

#### GCOE lecture series

15:30-17:00 Room #122 (Graduate School of Math. Sci. Bldg.)

TBA(中止になりました) (ENGLISH)

**Mihai Paun**(Institut Élie Cartan and KIAS)TBA(中止になりました) (ENGLISH)

### 2012/01/17

#### Tuesday Seminar on Topology

16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)

On the Johnson cokernels of the mapping class group of a surface (joint work with Naoya Enomoto) (JAPANESE)

**Takao Satoh**(Tokyo University of Science)On the Johnson cokernels of the mapping class group of a surface (joint work with Naoya Enomoto) (JAPANESE)

[ Abstract ]

In general, the Johnson homomorphisms of the mapping class group of a surface are used to investigate graded quotients of the Johnson filtration of the mapping class group. These graded quotients are considered as a sequence of approximations of the Torelli group. Now, there is a broad range of remarkable results for the Johnson homomorphisms.

In this talk, we concentrate our focus on the cokernels of the Johnson homomorphisms of the mapping class group. By a work of Shigeyuki Morita and Hiroaki Nakamura, it is known that an Sp-irreducible module [k] appears in the cokernel of the k-th Johnson homomorphism with multiplicity one if k=2m+1 for any positive integer m. In general, however, to determine Sp-structure of the cokernel is quite a difficult preblem.

Our goal is to show that we have detected new irreducible components in the cokernels. More precisely, we will show that there appears an Sp-irreducible module [1^k] in the cokernel of the k-th Johnson homomorphism with multiplicity one if k=4m+1 for any positive integer m.

In general, the Johnson homomorphisms of the mapping class group of a surface are used to investigate graded quotients of the Johnson filtration of the mapping class group. These graded quotients are considered as a sequence of approximations of the Torelli group. Now, there is a broad range of remarkable results for the Johnson homomorphisms.

In this talk, we concentrate our focus on the cokernels of the Johnson homomorphisms of the mapping class group. By a work of Shigeyuki Morita and Hiroaki Nakamura, it is known that an Sp-irreducible module [k] appears in the cokernel of the k-th Johnson homomorphism with multiplicity one if k=2m+1 for any positive integer m. In general, however, to determine Sp-structure of the cokernel is quite a difficult preblem.

Our goal is to show that we have detected new irreducible components in the cokernels. More precisely, we will show that there appears an Sp-irreducible module [1^k] in the cokernel of the k-th Johnson homomorphism with multiplicity one if k=4m+1 for any positive integer m.

#### Numerical Analysis Seminar

17:00-18:00 Room #123 (Graduate School of Math. Sci. Bldg.)

Numerical computations of flow problems with the moving boundary by an area-preserving scheme (JAPANESE)

[ Reference URL ]

http://www.infsup.jp/utnas/

**Daisuke Tagami**(Kyushu University)Numerical computations of flow problems with the moving boundary by an area-preserving scheme (JAPANESE)

[ Reference URL ]

http://www.infsup.jp/utnas/

### 2012/01/16

#### Algebraic Geometry Seminar

15:30-17:00 Room #122 (Graduate School of Math. Sci. Bldg.)

TBA(Cancelled) (JAPANESE)

**Mihai Paun**(Institut Élie Cartan and KIAS)TBA(Cancelled) (JAPANESE)

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #128 (Graduate School of Math. Sci. Bldg.)

A ramification theorem for the ratio of canonical forms of flat surfaces in hyperbolic 3-space (JAPANESE)

**Yu Kawakami**(Yamaguchi University)A ramification theorem for the ratio of canonical forms of flat surfaces in hyperbolic 3-space (JAPANESE)

[ Abstract ]

We provide an effective ramification theorem for the ratio of canonical forms of weakly complete flat fronts in the hyperbolic 3-space. As an application, we give a simple proof of the classification of complete nonsingular flat surfaces in the hyperbolic 3-space.

We provide an effective ramification theorem for the ratio of canonical forms of weakly complete flat fronts in the hyperbolic 3-space. As an application, we give a simple proof of the classification of complete nonsingular flat surfaces in the hyperbolic 3-space.

#### Operator Algebra Seminars

16:30-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)

Is an irng singly generated as an ideal? (JAPANESE)

**Narutaka Ozawa**(RIMS, Kyoto University)Is an irng singly generated as an ideal? (JAPANESE)

#### GCOE lecture series

15:30-17:00 Room #122 (Graduate School of Math. Sci. Bldg.)

TBA(中止になりました) (ENGLISH)

**Mihai Paun**(Institut Élie Cartan and KIAS)TBA(中止になりました) (ENGLISH)

### 2012/01/12

#### Number Theory Seminar

18:15-19:15 Room #056 (Graduate School of Math. Sci. Bldg.)

New perspectives on the Breuil-Mézard conjecture (joint with M. Emerton)

(ENGLISH)

**Toby Gee**(Imperial College London)New perspectives on the Breuil-Mézard conjecture (joint with M. Emerton)

(ENGLISH)

[ Abstract ]

I will discuss joint work with Matthew Emerton on geometric approaches to the Breuil-Mézard conjecture, generalising a geometric approach of Breuil and Mézard. I will discuss a proof of the geometric version of the original conjecture, as well as work in progress on a geometric version of the conjecture which does not make use of a fixed residual representation.

(本講演は「東京パリ数論幾何セミナー」として、インターネットによる東大数理とIHESとの双方向同時中継で行います。)

I will discuss joint work with Matthew Emerton on geometric approaches to the Breuil-Mézard conjecture, generalising a geometric approach of Breuil and Mézard. I will discuss a proof of the geometric version of the original conjecture, as well as work in progress on a geometric version of the conjecture which does not make use of a fixed residual representation.

(本講演は「東京パリ数論幾何セミナー」として、インターネットによる東大数理とIHESとの双方向同時中継で行います。)

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