## Seminar information archive

Seminar information archive ～02/21｜Today's seminar 02/22 | Future seminars 02/23～

### 2013/08/07

#### FMSP Lectures

16:00-17:00 Room #370 (Graduate School of Math. Sci. Bldg.)

Water waves over a random bottom (ENGLISH)

**Philippe Guyenne**(Univ. of Delaware)Water waves over a random bottom (ENGLISH)

[ Abstract ]

We present a Hamiltonian formulation for nonlinear surface water waves in the presence of a variable bottom. This formulation is based on a reduction of the problem to a lower-dimensional system involving boundary variables alone. To accomplish this, we express the Dirichlet-to-Neumann operator as a Taylor series in terms of the surface and bottom variations. This expansion is convenient for both asymptotic calculations and numerical simulations. First we apply this formulation to the asymptotic description of long waves over random topography. We show that the principal component of the solution can be described by a Korteweg-de Vries equation plus random phase corrections. We also derive an asymptotic expression for the scattered component. Finally numerical simulations will be shown to illustrate the theoretical results. This is joint work with Walter Craig and Catherine Sulem.

We present a Hamiltonian formulation for nonlinear surface water waves in the presence of a variable bottom. This formulation is based on a reduction of the problem to a lower-dimensional system involving boundary variables alone. To accomplish this, we express the Dirichlet-to-Neumann operator as a Taylor series in terms of the surface and bottom variations. This expansion is convenient for both asymptotic calculations and numerical simulations. First we apply this formulation to the asymptotic description of long waves over random topography. We show that the principal component of the solution can be described by a Korteweg-de Vries equation plus random phase corrections. We also derive an asymptotic expression for the scattered component. Finally numerical simulations will be shown to illustrate the theoretical results. This is joint work with Walter Craig and Catherine Sulem.

### 2013/07/29

#### Mathematical Biology Seminar

16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)

Characteristic changes by time delay in the solution of differential equation and their applications (JAPANESE)

**Yoichi Enatsu**(Graduate School of Mathematical Sciences, University of Tokyo)Characteristic changes by time delay in the solution of differential equation and their applications (JAPANESE)

### 2013/07/26

#### thesis presentations

13:00-14:15 Room #122 (Graduate School of Math. Sci. Bldg.)

Examples of factors which have no Cartan subalgebras(カルタン部分環を持たない因子環の例) (JAPANESE)

**Yusuke ISONO**(Guraduate School of Mathematical Sciences the University of Tokyo)Examples of factors which have no Cartan subalgebras(カルタン部分環を持たない因子環の例) (JAPANESE)

#### FMSP Lectures

10:30-12:00 Room #118 (Graduate School of Math. Sci. Bldg.)

Representations of reductive groups and L-functions (II) (ENGLISH)

**Birgit Speh**(Cornell University)Representations of reductive groups and L-functions (II) (ENGLISH)

[ Abstract ]

In the second lecture we will quickly discuss Rankin Selberg integral approach to L-factors and then Shahidi's method of constructing L-functions by relating them to intertwining operators, leading to the definition of the the L-factors of tempered non degenerate representations. The lecture closes with a discussion of L-factors for nontempered representations.

In the second lecture we will quickly discuss Rankin Selberg integral approach to L-factors and then Shahidi's method of constructing L-functions by relating them to intertwining operators, leading to the definition of the the L-factors of tempered non degenerate representations. The lecture closes with a discussion of L-factors for nontempered representations.

#### Colloquium

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

Analysis of the Navier-Stokes and Complex Fluids Flow (ENGLISH)

**Matthias Hieber**(TU Darmstadt, Germany)Analysis of the Navier-Stokes and Complex Fluids Flow (ENGLISH)

[ Abstract ]

In this talk, we discuss the dynamics of fluid flow generated by the Navier-Stokes equations or, more generally, by models describing complex fluid flows. Besides classical questions concerning well-posedness of the underlying equations, we investigate analytically models arising in the theory of free boundary value problems, viscoelastic fluids and liquid crystals.

In this talk, we discuss the dynamics of fluid flow generated by the Navier-Stokes equations or, more generally, by models describing complex fluid flows. Besides classical questions concerning well-posedness of the underlying equations, we investigate analytically models arising in the theory of free boundary value problems, viscoelastic fluids and liquid crystals.

### 2013/07/25

#### thesis presentations

15:00-16:15 Room #122 (Graduate School of Math. Sci. Bldg.)

Discrete integrable equations over finite fields(有限体上の離散可積分方程式) (JAPANESE)

**Masataka KANKI**(Guraduate School of Mathematical Sciences the University of Tokyo)Discrete integrable equations over finite fields(有限体上の離散可積分方程式) (JAPANESE)

#### Lectures

13:00-15:00 Room #126 (Graduate School of Math. Sci. Bldg.)

)

Quantum Chern-Simons field theory (ENGLISH)

**Joergen E Andersen**(Centre for Quantum Geometry of Moduli Spaces (QGM), Aarhus University, Denmark)

Quantum Chern-Simons field theory (ENGLISH)

### 2013/07/24

#### Number Theory Seminar

16:40-17:40 Room #056 (Graduate School of Math. Sci. Bldg.)

The determinant of a double covering of the projective space of even dimension and the discriminant of the branch locus (JAPANESE)

**Yasuhiro Terakado**(University of Tokyo)The determinant of a double covering of the projective space of even dimension and the discriminant of the branch locus (JAPANESE)

#### Operator Algebra Seminars

16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)

The sofic property for groups and dynamical systems (ENGLISH)

**Mikael Pichot**(McGill Univ.)The sofic property for groups and dynamical systems (ENGLISH)

### 2013/07/23

#### PDE Real Analysis Seminar

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

Analysis of the Simplified Ericksen-Leslie Model for Liquid Crystals (ENGLISH)

**Matthias Hieber**(Technische Universität Darmstadt)Analysis of the Simplified Ericksen-Leslie Model for Liquid Crystals (ENGLISH)

[ Abstract ]

Consider the Ericksen-Leslie model for the flow of liquid crystals in a bounded domain $\\Omega \\subset \\R^n$. In this talk we discuss various simplifications of the general model and describe a dynamic theory for the simplified equations by analyzing it as a quasilinear system. In particular, we show the existence of a unique, global, strong solutions to this system provided the initial data are close to an equilibrium or the solution is eventually bounded in the norm of the underlying state space. In this case the solution converges exponentially to an equilibrium. Moreover, the solution is shown to be real analytic, jointly in time and space.

We further analyze a non-isothermal extension of this model safisfying the first and second law of thermodynamics and show that results of the above type hold as well in this setting.

This is joint work with M. Nesensohn, J. Prüss and K. Schade.

Consider the Ericksen-Leslie model for the flow of liquid crystals in a bounded domain $\\Omega \\subset \\R^n$. In this talk we discuss various simplifications of the general model and describe a dynamic theory for the simplified equations by analyzing it as a quasilinear system. In particular, we show the existence of a unique, global, strong solutions to this system provided the initial data are close to an equilibrium or the solution is eventually bounded in the norm of the underlying state space. In this case the solution converges exponentially to an equilibrium. Moreover, the solution is shown to be real analytic, jointly in time and space.

We further analyze a non-isothermal extension of this model safisfying the first and second law of thermodynamics and show that results of the above type hold as well in this setting.

This is joint work with M. Nesensohn, J. Prüss and K. Schade.

#### Numerical Analysis Seminar

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

Boundary Integral Equation Method for several Laplace equations with crack(s) (JAPANESE)

[ Reference URL ]

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

**Akira Sasamoto**(National Institute of Advanced Industrial Science and Technology)Boundary Integral Equation Method for several Laplace equations with crack(s) (JAPANESE)

[ Reference URL ]

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

#### Lectures

13:00-15:00 Room #002 (Graduate School of Math. Sci. Bldg.)

)

Moduli space approach for protein structures (ENGLISH)

**Joergen E Andersen**(Centre for Quantum Geometry of Moduli Spaces (QGM), Aarhus University, Denmark)

Moduli space approach for protein structures (ENGLISH)

### 2013/07/22

#### thesis presentations

13:30-14:45 Room #128 (Graduate School of Math. Sci. Bldg.)

The Stokes semigroup on non-decaying spaces(非減衰空間上のストークス半群) (JAPANESE)

**Ken ABE**(Guraduate School of Mathematical Sciences the University of Tokyo)The Stokes semigroup on non-decaying spaces(非減衰空間上のストークス半群) (JAPANESE)

#### thesis presentations

15:30-16:45 Room #128 (Graduate School of Math. Sci. Bldg.)

A few topics related to maximum principles(最大値原理に関連する諸課題) (JAPANESE)

**Nao HAMAMUKI**(Guraduate School of Mathematical Sciences the University of Tokyo)A few topics related to maximum principles(最大値原理に関連する諸課題) (JAPANESE)

#### Algebraic Geometry Seminar

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

Equivariant degenerations of spherical modules (ENGLISH)

**Stavros Papadakis**(RIMS)Equivariant degenerations of spherical modules (ENGLISH)

[ Abstract ]

Given a reductive algebraic group G and an invariant

Hilbert function h, Alexeev and Brion have defined

a moduli scheme M which parametrizes affine G-schemes X

with the property that the coordinate ring of X decomposes,

as G-module, according to the function h. The talk will

be about joint work with Bart Van Steirteghem (New York)

which studies the moduli scheme M under some additional

assumptions.

Given a reductive algebraic group G and an invariant

Hilbert function h, Alexeev and Brion have defined

a moduli scheme M which parametrizes affine G-schemes X

with the property that the coordinate ring of X decomposes,

as G-module, according to the function h. The talk will

be about joint work with Bart Van Steirteghem (New York)

which studies the moduli scheme M under some additional

assumptions.

#### Lectures

13:00-15:00 Room #126 (Graduate School of Math. Sci. Bldg.)

)

Moduli space approach for RNA structure analysis (ENGLISH)

**Joergen E Andersen**(Centre for Quantum Geometry of Moduli Spaces (QGM), Aarhus University, Denmark)

Moduli space approach for RNA structure analysis (ENGLISH)

### 2013/07/20

#### Harmonic Analysis Komaba Seminar

13:00-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Existence of Weak Solutions for a Diffuse Interface Model of Non-Newtonian Two-Phase Flows

(JAPANESE)

On the smoothness conditions for bilinear Fourier multipliers (JAPANESE)

**Yutaka Terasawa**(The University of Tokyo) 13:30-15:00Existence of Weak Solutions for a Diffuse Interface Model of Non-Newtonian Two-Phase Flows

(JAPANESE)

**Naohito Tomita**(Osaka University) 15:30-17:00On the smoothness conditions for bilinear Fourier multipliers (JAPANESE)

### 2013/07/18

#### Mathematical Biology Seminar

16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)

Path integral representaion and Euler-Lotka equation in age-size structured population model (JAPANESE)

**Ryo Oizumi**(Graduate School of Environmental Science, Hokkaido University)Path integral representaion and Euler-Lotka equation in age-size structured population model (JAPANESE)

#### FMSP Lectures

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

Representations of reductive groups and L-functions (I) (ENGLISH)

**Birgit Speh**(Cornell University)Representations of reductive groups and L-functions (I) (ENGLISH)

[ Abstract ]

This is an introduction to the theory of L-functions and in particular of the local L-factors of representations in real and complex groups. Some familiarity with infinite dimensional representations would be very helpful, but I will not assume any knowledge of number theory. We will start in the first lecture by considering L-functions for Groessen characters and classical automorphic forms, in other words for automorphic representations of G(1) and GL(2). This will motivate the definition of the local L-factors of representations of GL(1,R) and GL(2,R). Then we will discuss Rankin convolutions and define the L-factors for infinite dimensional tempered representations of GL(n,R).

This is an introduction to the theory of L-functions and in particular of the local L-factors of representations in real and complex groups. Some familiarity with infinite dimensional representations would be very helpful, but I will not assume any knowledge of number theory. We will start in the first lecture by considering L-functions for Groessen characters and classical automorphic forms, in other words for automorphic representations of G(1) and GL(2). This will motivate the definition of the local L-factors of representations of GL(1,R) and GL(2,R). Then we will discuss Rankin convolutions and define the L-factors for infinite dimensional tempered representations of GL(n,R).

### 2013/07/17

#### Kavli IPMU Komaba Seminar

17:00-18:30 Room #002 (Graduate School of Math. Sci. Bldg.)

Homological Mirror Symmetry for toric Calabi-Yau varieties (ENGLISH)

**Daniel Pomerleano**(Kavli IPMU)Homological Mirror Symmetry for toric Calabi-Yau varieties (ENGLISH)

[ Abstract ]

I will discuss some recent developments in Homological Mirror

Symmetry for toric Calabi-Yau varieties.

I will discuss some recent developments in Homological Mirror

Symmetry for toric Calabi-Yau varieties.

### 2013/07/16

#### Tuesday Seminar on Topology

17:10-18:10 Room #056 (Graduate School of Math. Sci. Bldg.)

On new models of real hyperbolic spaces (JAPANESE)

**Sumio Yamada**(Gakushuin University)On new models of real hyperbolic spaces (JAPANESE)

[ Abstract ]

In this talk, I will introduce several new realization of the real hyperbolic spaces, using classical tools. The constructions will involve aspects of convex geometry as well as projective geometry, and they are interesting from the view point of the history of mathematics. This work belongs to a joint project with Athanase Papadopoulos.

In this talk, I will introduce several new realization of the real hyperbolic spaces, using classical tools. The constructions will involve aspects of convex geometry as well as projective geometry, and they are interesting from the view point of the history of mathematics. This work belongs to a joint project with Athanase Papadopoulos.

#### Numerical Analysis Seminar

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

Numerical computation of motion of interface networks (JAPANESE)

[ Reference URL ]

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

**Karel Svadlenka**(Kanazawa University)Numerical computation of motion of interface networks (JAPANESE)

[ Reference URL ]

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

### 2013/07/11

#### Geometry Colloquium

10:00-11:30 Room #122 (Graduate School of Math. Sci. Bldg.)

Primitive forms via polyvector fields (ENGLISH)

**Changzheng Li**(IPMU)Primitive forms via polyvector fields (ENGLISH)

[ Abstract ]

The theory of primitive forms was introduced by Kyoji Saito in early 1980s, which was first known in singularity theory and has attracted much attention in mirror symmetry recently. In this talk, we will introduce a differential geometric approach to primitive forms, using compactly supported polyvector fields. We will first introduce the notion of primitive forms, making it acceptable to general audience. We will use the example of the mirror Laudau-Ginzberg model of P^1 to illustrate such approach. This is my joint work with Si Li and Kyoji Saito.

The theory of primitive forms was introduced by Kyoji Saito in early 1980s, which was first known in singularity theory and has attracted much attention in mirror symmetry recently. In this talk, we will introduce a differential geometric approach to primitive forms, using compactly supported polyvector fields. We will first introduce the notion of primitive forms, making it acceptable to general audience. We will use the example of the mirror Laudau-Ginzberg model of P^1 to illustrate such approach. This is my joint work with Si Li and Kyoji Saito.

### 2013/07/10

#### Number Theory Seminar

17:00-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)

On ramification filtration of local fields of equal characteristic (JAPANESE)

**Yuri Yatagawa**(University of Tokyo)On ramification filtration of local fields of equal characteristic (JAPANESE)

### 2013/07/09

#### Tuesday Seminar on Topology

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

Smooth 3-manifolds in the 4-sphere (ENGLISH)

**Ryan Budney**(University of Victoria)Smooth 3-manifolds in the 4-sphere (ENGLISH)

[ Abstract ]

Everyone who has studied topology knows the compact 2-manifolds that embed in the 3-sphere. One dimension up, the problem of which smooth 3-manifolds embed in the 4-sphere turns out to be much more involved with a handful of partial answers. I will describe what is known at the present moment.

Everyone who has studied topology knows the compact 2-manifolds that embed in the 3-sphere. One dimension up, the problem of which smooth 3-manifolds embed in the 4-sphere turns out to be much more involved with a handful of partial answers. I will describe what is known at the present moment.

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