## Seminar information archive

Seminar information archive ～09/15｜Today's seminar 09/16 | Future seminars 09/17～

### 2013/10/17

#### GCOE Seminars

16:00-17:00 Room #470 (Graduate School of Math. Sci. Bldg.)

Stability for Inverse problems for Ultrahyperbolic Equations (ENGLISH)

**Fikret Goelgeleyen**(Bulent Ecevit University)Stability for Inverse problems for Ultrahyperbolic Equations (ENGLISH)

[ Abstract ]

In this work, we consider inverse problems of determining a coefficient or a source term in an ultrahyperbolic equation by some lateral boundary data.

We prove Hoelder estimates which are global and local and the key is Carleman estimates.

In this work, we consider inverse problems of determining a coefficient or a source term in an ultrahyperbolic equation by some lateral boundary data.

We prove Hoelder estimates which are global and local and the key is Carleman estimates.

#### GCOE Seminars

17:00-18:00 Room #470 (Graduate School of Math. Sci. Bldg.)

Fluid-structure interaction model and Levelset method (ENGLISH)

**kazufumi Ito**(North Carolina State University)Fluid-structure interaction model and Levelset method (ENGLISH)

[ Abstract ]

We derive a weak form and weak solution of the level set formulation of Cottet and Maitre for fluid-structure interaction problems with immersed surfaces. The method in particular exhibits appealing mass and energy conservation properties and a variational formulation of Peskin’s Immersed Boundary methods.

We derive a weak form and weak solution of the level set formulation of Cottet and Maitre for fluid-structure interaction problems with immersed surfaces. The method in particular exhibits appealing mass and energy conservation properties and a variational formulation of Peskin’s Immersed Boundary methods.

### 2013/10/16

#### Number Theory Seminar

17:30-18:30 Room #056 (Graduate School of Math. Sci. Bldg.)

Shimura varieties with infinite level, and torsion in the cohomology of locally symmetric spaces (ENGLISH)

**Peter Scholze**(Universität Bonn)Shimura varieties with infinite level, and torsion in the cohomology of locally symmetric spaces (ENGLISH)

[ Abstract ]

We will discuss the p-adic geometry of Shimura varieties with infinite level at p: They are perfectoid spaces, and there is a new period map defined at infinite level. As an application, we will discuss some results on torsion in the cohomology of locally symmetric spaces, and in particular the existence of Galois representations in this setup.

We will discuss the p-adic geometry of Shimura varieties with infinite level at p: They are perfectoid spaces, and there is a new period map defined at infinite level. As an application, we will discuss some results on torsion in the cohomology of locally symmetric spaces, and in particular the existence of Galois representations in this setup.

#### Operator Algebra Seminars

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

Some prime factorization results for free quantum group factors (JAPANESE)

**Yusuke Isono**(Univ. Tokyo)Some prime factorization results for free quantum group factors (JAPANESE)

#### Seminar on Probability and Statistics

13:30-14:40 Room #052 (Graduate School of Math. Sci. Bldg.)

統計解析環境Rにおける多変量GARCHモデルの推定とパッケージ化 (JAPANESE)

[ Reference URL ]

http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/03.html

**NAKATANI, Tomoaki**(Hokkaido University)統計解析環境Rにおける多変量GARCHモデルの推定とパッケージ化 (JAPANESE)

[ Reference URL ]

http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/03.html

### 2013/10/15

#### Tuesday Seminar on Topology

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

Desingularizing special generic maps (JAPANESE)

**Masamichi Takase**(Seikei University)Desingularizing special generic maps (JAPANESE)

[ Abstract ]

This is a joint work with Osamu Saeki (IMI, Kyushu University).

A special generic map is a generic map which has only definite

fold as its singularities.

We study the condition for a special generic map from a closed

n-manifold to the p-space (n+1>p), to factor through a codimension

one immersion (or an embedding). In particular, for the cases

where p = 1 and 2 we obtain complete results.

Our techniques are related to Smale-Hirsch theory,

topology of the space of immersions, relation between the space

of topological immersions and that of smooth immersions,

sphere eversions, differentiable structures of homotopy spheres,

diffeomorphism group of spheres, free group actions on the sphere, etc.

This is a joint work with Osamu Saeki (IMI, Kyushu University).

A special generic map is a generic map which has only definite

fold as its singularities.

We study the condition for a special generic map from a closed

n-manifold to the p-space (n+1>p), to factor through a codimension

one immersion (or an embedding). In particular, for the cases

where p = 1 and 2 we obtain complete results.

Our techniques are related to Smale-Hirsch theory,

topology of the space of immersions, relation between the space

of topological immersions and that of smooth immersions,

sphere eversions, differentiable structures of homotopy spheres,

diffeomorphism group of spheres, free group actions on the sphere, etc.

### 2013/10/12

#### Harmonic Analysis Komaba Seminar

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

The global Cauchy problems for nonlinear dispersive equations on modulation spaces

(JAPANESE)

Path Integrals--Analysis on path space by time-slicing method (JAPANESE)

**Tomoya Kato**(Nagoya University) 13:30-15:00The global Cauchy problems for nonlinear dispersive equations on modulation spaces

(JAPANESE)

**Naoto Kumanogo**(Kogakuin University) 15:30-17:00Path Integrals--Analysis on path space by time-slicing method (JAPANESE)

### 2013/10/09

#### Operator Algebra Seminars

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

Graphs of quantum groups and K-amenability (ENGLISH)

**Pierre Fima**(Univ. Paris VII)Graphs of quantum groups and K-amenability (ENGLISH)

#### GCOE Seminars

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

Determination of the first order terms for elliptic partial differential equations using the partial Cauchy data (ENGLISH)

**Oleg Emanouilov**(Colorado State Univ.)Determination of the first order terms for elliptic partial differential equations using the partial Cauchy data (ENGLISH)

[ Abstract ]

In the bounded domain we consider the variant of the Calderon's problem for the second order partial differential equation with unknown first order terms. Under some geometric condition on domain we prove that the coefficients of this equation can be determined from the partial Cauchy data up to the gauge equivalence.

In the bounded domain we consider the variant of the Calderon's problem for the second order partial differential equation with unknown first order terms. Under some geometric condition on domain we prove that the coefficients of this equation can be determined from the partial Cauchy data up to the gauge equivalence.

### 2013/10/08

#### Tuesday Seminar on Topology

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

An invariant of rational homology 3-spheres via vector fields. (JAPANESE)

**Tatsuro Shimizu**(The Univesity of Tokyo)An invariant of rational homology 3-spheres via vector fields. (JAPANESE)

[ Abstract ]

In this talk, we define an invariant of rational homology 3-spheres with

values in a space $\\mathcal A(\\emptyset)$ of Jacobi diagrams by using

vector fields.

The construction of our invariant is a generalization of both that of

the Kontsevich-Kuperberg-Thurston invariant $z^{KKT}$

and that of Fukaya and Watanabe's Morse homotopy invariant $z^{FW}$.

As an application of our invariant, we prove that $z^{KKT}=z^{FW}$ for

integral homology 3-spheres.

In this talk, we define an invariant of rational homology 3-spheres with

values in a space $\\mathcal A(\\emptyset)$ of Jacobi diagrams by using

vector fields.

The construction of our invariant is a generalization of both that of

the Kontsevich-Kuperberg-Thurston invariant $z^{KKT}$

and that of Fukaya and Watanabe's Morse homotopy invariant $z^{FW}$.

As an application of our invariant, we prove that $z^{KKT}=z^{FW}$ for

integral homology 3-spheres.

### 2013/10/07

#### Seminar on Geometric Complex Analysis

10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)

The limits on boundary of orbifold Kähler-Einstein metrics and orbifold Kähler-Ricci flows over quasi-projective manifolds (JAPANESE)

**Shin Kikuta**(Sophia University)The limits on boundary of orbifold Kähler-Einstein metrics and orbifold Kähler-Ricci flows over quasi-projective manifolds (JAPANESE)

[ Abstract ]

In this talk, we consider a sequence of orbifold Kähler-Einstein metrics of negative Ricci curvature or corresponding orbifold normalized Kähler-Ricci flows on a quasi-projective manifold with ample log-canonical bundle for a simple normal crossing divisor. Tian-Yau, S. Bando and H. Tsuji established that the sequence of orbifold Kähler-Einstein metrics converged to the complete Käler-Einstein metric of negative Ricci curvature on the complement of the boundary divisor. The main purpose of this talk is to show that such a convergence is also true on the boundary for both of the orbifold Kähler-Einstein metrics and the orbifold normalized Kähler-Ricci flows.

In this talk, we consider a sequence of orbifold Kähler-Einstein metrics of negative Ricci curvature or corresponding orbifold normalized Kähler-Ricci flows on a quasi-projective manifold with ample log-canonical bundle for a simple normal crossing divisor. Tian-Yau, S. Bando and H. Tsuji established that the sequence of orbifold Kähler-Einstein metrics converged to the complete Käler-Einstein metric of negative Ricci curvature on the complement of the boundary divisor. The main purpose of this talk is to show that such a convergence is also true on the boundary for both of the orbifold Kähler-Einstein metrics and the orbifold normalized Kähler-Ricci flows.

### 2013/10/03

#### Geometry Colloquium

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

A rigidity lemma for cocycles over BS(1,k)-actions (JAPANESE)

**Masayuki ASAOKA**(Kyoto University)A rigidity lemma for cocycles over BS(1,k)-actions (JAPANESE)

[ Abstract ]

Existence of an invariant geometric structure is persistent for many known examples of group actions on homogeneous spaces. In this talk, I would like to report an attempt to explain such a rigidity from a unified point of view. We will see that some rigidity results are reduced to a rigidity lemma on Diff(R^n,0)-valued cocycles over BS(1,k)-actions, where BS(1,k) is the Baumslag-Solitar group .

Existence of an invariant geometric structure is persistent for many known examples of group actions on homogeneous spaces. In this talk, I would like to report an attempt to explain such a rigidity from a unified point of view. We will see that some rigidity results are reduced to a rigidity lemma on Diff(R^n,0)-valued cocycles over BS(1,k)-actions, where BS(1,k) is the Baumslag-Solitar group .

### 2013/10/02

#### Operator Algebra Seminars

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

A classification of flows on AFD factors with faithful Connes-Takesaki modules

(JAPANESE)

**Koichi Shimada**(Univ. Tokyo)A classification of flows on AFD factors with faithful Connes-Takesaki modules

(JAPANESE)

### 2013/10/01

#### Tuesday Seminar on Topology

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

The geography problem of Lefschetz fibrations (JAPANESE)

**Naoyuki Monden**(Tokyo University of Science)The geography problem of Lefschetz fibrations (JAPANESE)

[ Abstract ]

To consider holomorphic fibrations complex surfaces over complex curves

and Lefschetz fibrations over surfaces is one method for the study of

complex surfaces of general type and symplectic 4-manifods, respectively.

In this talk, by comparing the geography problem of relatively minimal

holomorphic fibrations with that of relatively minimal Lefschetz

fibrations (i.e., the characterization of pairs $(x,y)$ of certain

invariants $x$ and $y$ corresponding to relatively minimal holomorphic

fibrations and relatively minimal Lefschetz fibrations), we observe the

difference between complex surfaces of general type and symplectic

4-manifolds. In particular, we construct Lefschetz fibrations violating

the ``slope inequality" which holds for any relatively minimal holomorphic

fibrations.

To consider holomorphic fibrations complex surfaces over complex curves

and Lefschetz fibrations over surfaces is one method for the study of

complex surfaces of general type and symplectic 4-manifods, respectively.

In this talk, by comparing the geography problem of relatively minimal

holomorphic fibrations with that of relatively minimal Lefschetz

fibrations (i.e., the characterization of pairs $(x,y)$ of certain

invariants $x$ and $y$ corresponding to relatively minimal holomorphic

fibrations and relatively minimal Lefschetz fibrations), we observe the

difference between complex surfaces of general type and symplectic

4-manifolds. In particular, we construct Lefschetz fibrations violating

the ``slope inequality" which holds for any relatively minimal holomorphic

fibrations.

### 2013/09/10

#### Monthly Seminar on Arithmetic of Automorphic Forms

13:30-15:00 Room #123 (Graduate School of Math. Sci. Bldg.)

Counting automorphic representations (JAPANESE)

Counting automorphic representations II (Sept. 17) (JAPANESE)

**Yuval Flicker**(Ohio State Univ.) 13:30-15:00Counting automorphic representations (JAPANESE)

**Yuval Flicker**(Ohio State University) 13:30-15:00Counting automorphic representations II (Sept. 17) (JAPANESE)

### 2013/09/07

#### FMSP Lectures

15:00-16:30 Room #123 (Graduate School of Math. Sci. Bldg.)

Dominating representations by Fuchsian ones (ENGLISH)

**Bertrand Deroin**(University of Paris-Sud)Dominating representations by Fuchsian ones (ENGLISH)

[ Abstract ]

We will focus on the problem of dominating the translation lengths of a representation from a surface group to the isometries of a CAT(-1) space by the lengths induced by a hyperbolic structure on the surface. This is related to the construction of 3-dimensional anti-de-Sitter compact manifolds. This is a collaboration with Nicolas Tholozan.

We will focus on the problem of dominating the translation lengths of a representation from a surface group to the isometries of a CAT(-1) space by the lengths induced by a hyperbolic structure on the surface. This is related to the construction of 3-dimensional anti-de-Sitter compact manifolds. This is a collaboration with Nicolas Tholozan.

### 2013/08/12

#### Operator Algebra Seminars

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

Operator Algebraic Construction of Quantum Field Theory Models (ENGLISH)

**Roberto Longo**(Univ. Roma, Tor Vergata)Operator Algebraic Construction of Quantum Field Theory Models (ENGLISH)

#### FMSP Lectures

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

Operator Algebraic Construction of Quantum Field Theory Models (ENGLISH)

**Roberto Longo**(Univ. Roma, Tor Vergata)Operator Algebraic Construction of Quantum Field Theory Models (ENGLISH)

### 2013/08/09

#### Operator Algebra Seminars

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

Cellular automata and groups (ENGLISH)

**Tullio Ceccherini-Silberstein**(Univ. Sannio)Cellular automata and groups (ENGLISH)

### 2013/08/08

#### Operator Algebra Seminars

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

Phase Plane Operator Valued Probability Measures: Constructions and Random Evolution (ENGLISH)

**Demosthenes Ellinas**(Technical University of Crete)Phase Plane Operator Valued Probability Measures: Constructions and Random Evolution (ENGLISH)

### 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.

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