## Seminar information archive

Seminar information archive ～02/06｜Today's seminar 02/07 | Future seminars 02/08～

### 2013/05/25

#### Harmonic Analysis Komaba Seminar

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

Multilinear fractional integral operators on weighted Morrey spaces (JAPANESE)

On factorization of divergence form elliptic operators

and its application

(JAPANESE)

**Takeshi Iida**(Fukushima National College of Technology) 13:30-15:00Multilinear fractional integral operators on weighted Morrey spaces (JAPANESE)

**Yasunori Maekawa**(Tohoku University) 15:30-17:00On factorization of divergence form elliptic operators

and its application

(JAPANESE)

### 2013/05/24

#### Lectures

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

Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (JAPANESE)

**Laurent Lafforgue**(IHES)Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (JAPANESE)

### 2013/05/21

#### Tuesday Seminar of Analysis

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

Homogenization in a Thin Layer with an Oscillating Interface and Highly Contrast Coefficients (JAPANESE)

**Masaaki Uesaka**(Graduate School of Mathematical Sciences, The University of Tokyo)Homogenization in a Thin Layer with an Oscillating Interface and Highly Contrast Coefficients (JAPANESE)

[ Abstract ]

We consider the homogenization problem of the elliptic boundary value problem in a thin domain which has a high and low conductivity zones. In our model, two media are separated by a highly oscillating interface. The asymptotic behavior is governed by the order of the thickness of the domain, oscillation period of the interface and contrast between two media. In this talk, we show that the limit problem is changed by these parameters. We also introduce the two-scale convergence result in a thin domain which is the key ingredient of the proof.

We consider the homogenization problem of the elliptic boundary value problem in a thin domain which has a high and low conductivity zones. In our model, two media are separated by a highly oscillating interface. The asymptotic behavior is governed by the order of the thickness of the domain, oscillation period of the interface and contrast between two media. In this talk, we show that the limit problem is changed by these parameters. We also introduce the two-scale convergence result in a thin domain which is the key ingredient of the proof.

#### Lectures

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

Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)

**Laurent Lafforgue**(IHES)Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)

#### Tuesday Seminar on Topology

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

A Heegaard Floer homology for bipartite spatial graphs and its

properties (ENGLISH)

**Yuanyuan Bao**(The University of Tokyo)A Heegaard Floer homology for bipartite spatial graphs and its

properties (ENGLISH)

[ Abstract ]

A spatial graph is a smooth embedding of a graph into a given

3-manifold. We can regard a link as a particular spatial graph.

So it is natural to ask whether it is possible to extend the idea

of link Floer homology to define a Heegaard Floer homology for

spatial graphs. In this talk, we discuss some ideas towards this

question. In particular, we define a Heegaard Floer homology for

bipartite spatial graphs and discuss some further observations

about this construction. We remark that Harvey and O’Donnol

have announced a combinatorial Floer homology for spatial graphs by

considering grid diagrams.

A spatial graph is a smooth embedding of a graph into a given

3-manifold. We can regard a link as a particular spatial graph.

So it is natural to ask whether it is possible to extend the idea

of link Floer homology to define a Heegaard Floer homology for

spatial graphs. In this talk, we discuss some ideas towards this

question. In particular, we define a Heegaard Floer homology for

bipartite spatial graphs and discuss some further observations

about this construction. We remark that Harvey and O’Donnol

have announced a combinatorial Floer homology for spatial graphs by

considering grid diagrams.

### 2013/05/20

#### Seminar on Geometric Complex Analysis

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

レヴィ平坦面の分類に関する最近の進展 (JAPANESE)

**Takeo Ohsawa**(Nagoya University)レヴィ平坦面の分類に関する最近の進展 (JAPANESE)

[ Abstract ]

レヴィ平坦面の分類がCP^2の場合にできていないことから、種々の興味深い問題が生じているように思われる。ここではトーラスの場合に観察されたことをホップ曲面に拡げたとき、ホップ曲面においてならレヴィ平坦面の分類が(実解析的な場合に限るが)完全にできることを報告する。

レヴィ平坦面の分類がCP^2の場合にできていないことから、種々の興味深い問題が生じているように思われる。ここではトーラスの場合に観察されたことをホップ曲面に拡げたとき、ホップ曲面においてならレヴィ平坦面の分類が(実解析的な場合に限るが)完全にできることを報告する。

### 2013/05/17

#### Seminar on Probability and Statistics

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

Computing the normalizing constant of the Bingham family by the holonomic gradient method (JAPANESE)

[ Reference URL ]

http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/00.html

**SEI, Tomonari**(Department of Mathematics, Keio University)Computing the normalizing constant of the Bingham family by the holonomic gradient method (JAPANESE)

[ Reference URL ]

http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/00.html

### 2013/05/16

#### Geometry Colloquium

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

A generalization of Taub-NUT deformations (JAPANESE)

**Kota Hattori**(University of Tokyo)A generalization of Taub-NUT deformations (JAPANESE)

[ Abstract ]

Taub-NUT metric on C^2 is a complete Ricci-flat Kaehler metric which is not flat. It is obtained by the Taub-NUT deformations of the Euclidean metric on C^2 using an S^1 action. Taub-NUT deformations are known to be defined for toric hyperKaehler manifolds, and deform ALE metrics to non-ALE metrics. In this talk, I explain a generalization of Taub-NUT deformations by using noncommutative Lie groups.

Taub-NUT metric on C^2 is a complete Ricci-flat Kaehler metric which is not flat. It is obtained by the Taub-NUT deformations of the Euclidean metric on C^2 using an S^1 action. Taub-NUT deformations are known to be defined for toric hyperKaehler manifolds, and deform ALE metrics to non-ALE metrics. In this talk, I explain a generalization of Taub-NUT deformations by using noncommutative Lie groups.

### 2013/05/15

#### Operator Algebra Seminars

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

Rohlin Flows on Amalgamated Free Product Factors (ENGLISH)

**Koichi Shimada**(Univ. Tokyo)Rohlin Flows on Amalgamated Free Product Factors (ENGLISH)

#### Number Theory Seminar

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

Special values of zeta functions of singular varieties over finite fields via higher chow groups (JAPANESE)

**Hiroyasu Miyazaki**(University of Tokyo)Special values of zeta functions of singular varieties over finite fields via higher chow groups (JAPANESE)

### 2013/05/14

#### Tuesday Seminar on Topology

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

Vanishing cycles and homotopies of wrinkled fibrations (JAPANESE)

**Kenta Hayano**(Osaka University)Vanishing cycles and homotopies of wrinkled fibrations (JAPANESE)

[ Abstract ]

Wrinkled fibrations on closed 4-manifolds are stable

maps to closed surfaces with only indefinite singularities. Such

fibrations and variants of them have been studied for the past few years

to obtain new descriptions of 4-manifolds using mapping class groups.

Vanishing cycles of wrinkled fibrations play a key role in these studies.

In this talk, we will explain how homotopies of wrinkled fibrtions affect

their vanishing cycles. Part of the results in this talk is a joint work

with Stefan Behrens (Max Planck Institute for Mathematics).

Wrinkled fibrations on closed 4-manifolds are stable

maps to closed surfaces with only indefinite singularities. Such

fibrations and variants of them have been studied for the past few years

to obtain new descriptions of 4-manifolds using mapping class groups.

Vanishing cycles of wrinkled fibrations play a key role in these studies.

In this talk, we will explain how homotopies of wrinkled fibrtions affect

their vanishing cycles. Part of the results in this talk is a joint work

with Stefan Behrens (Max Planck Institute for Mathematics).

#### Lectures

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

Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)

**Laurent Lafforgue**(IHES)Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)

### 2013/05/13

#### Seminar on Geometric Complex Analysis

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

Geometry and analysis of isolated essential singularities and their applications (JAPANESE)

**Yusuke Okuyama**(Kyoto Institute of Technology)Geometry and analysis of isolated essential singularities and their applications (JAPANESE)

[ Abstract ]

We establish a rescaling principle for isolated essential singularities of holomorphic curves and quasiregular mappings, and gives several applications of it in the theory of value distribution and dynamics. This is a joint work with Pekka Pankka.

We establish a rescaling principle for isolated essential singularities of holomorphic curves and quasiregular mappings, and gives several applications of it in the theory of value distribution and dynamics. This is a joint work with Pekka Pankka.

### 2013/05/11

#### Monthly Seminar on Arithmetic of Automorphic Forms

13:30-16:00 Room #123 (Graduate School of Math. Sci. Bldg.)

Symplectic-orthogonal theta lifts and explicit formulas for archimedean Whittaker functions (JAPANESE)

Infinite product represenation of the Mumford form and its application to the values of Selberg zeta functions (JAPANESE)

**Taku Ishii**(Seikei Univeristy) 13:30-14:30Symplectic-orthogonal theta lifts and explicit formulas for archimedean Whittaker functions (JAPANESE)

**Takashi Ichikawa**(Saga University) 15:00-16:00Infinite product represenation of the Mumford form and its application to the values of Selberg zeta functions (JAPANESE)

#### Infinite Analysis Seminar Tokyo

10:30-12:00 Room #117 (Graduate School of Math. Sci. Bldg.)

Saga of Dunkl elements (ENGLISH)

**Anatol Kirillov**(RIMS Kyoto Univ.)Saga of Dunkl elements (ENGLISH)

[ Abstract ]

The Dunkl operators has been introduced by C. Dunkl in the middle of

80's of the last century as a powerful mean in the study of orthogonal

polynomials related with finite Coxeter groups. Later it was discovered

a deep connection of the the Dunkl operators with the theory of

Integrable systems and Invariant Theory.

In my talk I introduce and study a certain class of nonhomogeneous

quadratic algebras together with the distinguish set of mutually

commuting elements inside of each, the so-called universal Dunkl elements.

The main problem I would like to discuss is : What is the algebra

generated by universal Dunkl elements in a different representations of

the quadratic algebra introduced ?

I'm planning to present partial answers on that problem related with

classical and quantum Schubert and Grothendieck Calculi as well as the

theory of elliptic series.

Also some interesting algebraic properties of the quadratic algebra(s)

in question will be described.

The Dunkl operators has been introduced by C. Dunkl in the middle of

80's of the last century as a powerful mean in the study of orthogonal

polynomials related with finite Coxeter groups. Later it was discovered

a deep connection of the the Dunkl operators with the theory of

Integrable systems and Invariant Theory.

In my talk I introduce and study a certain class of nonhomogeneous

quadratic algebras together with the distinguish set of mutually

commuting elements inside of each, the so-called universal Dunkl elements.

The main problem I would like to discuss is : What is the algebra

generated by universal Dunkl elements in a different representations of

the quadratic algebra introduced ?

I'm planning to present partial answers on that problem related with

classical and quantum Schubert and Grothendieck Calculi as well as the

theory of elliptic series.

Also some interesting algebraic properties of the quadratic algebra(s)

in question will be described.

### 2013/05/10

#### Lectures

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

Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)

**Laurent Lafforgue**(IHES)Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)

### 2013/05/09

#### Geometry Colloquium

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

Rigidity for amalgamated free products and their envelopes (JAPANESE)

**KIDA Yoshikata**(Kyoto University)Rigidity for amalgamated free products and their envelopes (JAPANESE)

[ Abstract ]

For a discrete countable group L, we mean by an envelope of L a locally compact second countable group having a lattice isomorphic to L. In general, it is quite hard to describe all envelopes of a given L. This problem is closely related to orbit equivalence between probability-measure-preserving actions of groups, and also related to Mostow type rigidity. I explain a fundamental idea to attack this problem, and give examples of groups for which the problem is solved. The examples contain mapping class groups of surfaces and certain amalgamated free products. An outline to get an answer for the latter groups will be discussed.

For a discrete countable group L, we mean by an envelope of L a locally compact second countable group having a lattice isomorphic to L. In general, it is quite hard to describe all envelopes of a given L. This problem is closely related to orbit equivalence between probability-measure-preserving actions of groups, and also related to Mostow type rigidity. I explain a fundamental idea to attack this problem, and give examples of groups for which the problem is solved. The examples contain mapping class groups of surfaces and certain amalgamated free products. An outline to get an answer for the latter groups will be discussed.

### 2013/05/08

#### Operator Algebra Seminars

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

Boundaries for Tensor Algebras (ENGLISH)

**Paul Muhly**(University of Iowa)Boundaries for Tensor Algebras (ENGLISH)

### 2013/05/07

#### Tuesday Seminar on Topology

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

Homological intersection in braid group representation and dual

Garside structure (JAPANESE)

**Tetsuya Ito**(RIMS, Kyoto University)Homological intersection in braid group representation and dual

Garside structure (JAPANESE)

[ Abstract ]

One method to construct linear representations of braid groups is to use

an action of braid groups on certain homology of local system coefficient.

Many famous representations, such as Burau or Lawrence-Krammer-Bigelow

representations are constructed in such a way. We show that homological

intersections on such homology groups are closely related to the dual

Garside structure, a remarkable combinatorial structure of braid, and

prove that some representations detects the length of braids in a

surprisingly simple way.

This work is partially joint with Bert Wiest (Univ. Rennes1).

One method to construct linear representations of braid groups is to use

an action of braid groups on certain homology of local system coefficient.

Many famous representations, such as Burau or Lawrence-Krammer-Bigelow

representations are constructed in such a way. We show that homological

intersections on such homology groups are closely related to the dual

Garside structure, a remarkable combinatorial structure of braid, and

prove that some representations detects the length of braids in a

surprisingly simple way.

This work is partially joint with Bert Wiest (Univ. Rennes1).

#### Numerical Analysis Seminar

16:30-18:00 Room #123 (Graduate School of Math. Sci. Bldg.)

Open problems on finite element analysis (JAPANESE)

[ Reference URL ]

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

**Takuya Tsuchiya**(Ehime University)Open problems on finite element analysis (JAPANESE)

[ Reference URL ]

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

### 2013/04/30

#### Lie Groups and Representation Theory

16:30-18:00 Room #126 (Graduate School of Math. Sci. Bldg.)

The homomorphisms between scalar generalized Verma modules of gl(n,C) with regular infinitesimal characters (JAPANESE)

**Hisayosi MATUMOTO**(Graduate School of Mathematical Sciences, the University of Tokyo)The homomorphisms between scalar generalized Verma modules of gl(n,C) with regular infinitesimal characters (JAPANESE)

[ Abstract ]

We will explain the classification of the homomorphisms between scalar generalized Verma modules of gl(n,C) with regular infinitesimal characters. In fact, they are compositions of elementary homomorphisms. The main ingredient of our proof is the translation principle in the mediocre region.

We will explain the classification of the homomorphisms between scalar generalized Verma modules of gl(n,C) with regular infinitesimal characters. In fact, they are compositions of elementary homomorphisms. The main ingredient of our proof is the translation principle in the mediocre region.

#### Tuesday Seminar on Topology

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

Discrete vector fields and fundamental algebraic topology.

(ENGLISH)

**Francis Sergeraert**(L'Institut Fourier, Univ. de Grenoble)Discrete vector fields and fundamental algebraic topology.

(ENGLISH)

[ Abstract ]

Robin Forman invented the notion of Discrete Vector Field in 1997.

A recent common work with Ana Romero allowed us to discover the notion

of Eilenberg-Zilber discrete vector field. Giving the topologist a

totally new understanding of the fundamental tools of combinatorial

algebraic topology: Eilenberg-Zilber theorem, twisted Eilenberg-Zilber

theorem, Serre and Eilenberg-Moore spectral sequences,

Eilenberg-MacLane correspondence between topological and algebraic

classifying spaces. Gives also new efficient algorithms for Algebraic

Topology, considerably improving our computer program Kenzo, devoted

to Constructive Algebraic Topology. The talk is devoted to an

introduction to discrete vector fields, the very simple definition of

the Eilenberg-Zilber vector field, and how it can be used in various

contexts.

Robin Forman invented the notion of Discrete Vector Field in 1997.

A recent common work with Ana Romero allowed us to discover the notion

of Eilenberg-Zilber discrete vector field. Giving the topologist a

totally new understanding of the fundamental tools of combinatorial

algebraic topology: Eilenberg-Zilber theorem, twisted Eilenberg-Zilber

theorem, Serre and Eilenberg-Moore spectral sequences,

Eilenberg-MacLane correspondence between topological and algebraic

classifying spaces. Gives also new efficient algorithms for Algebraic

Topology, considerably improving our computer program Kenzo, devoted

to Constructive Algebraic Topology. The talk is devoted to an

introduction to discrete vector fields, the very simple definition of

the Eilenberg-Zilber vector field, and how it can be used in various

contexts.

### 2013/04/24

#### Number Theory Seminar

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

Good reduction of ramified affinoids in the Lubin-Tate perfectoid space (ENGLISH)

**Naoki Imai**(University of Tokyo)Good reduction of ramified affinoids in the Lubin-Tate perfectoid space (ENGLISH)

[ Abstract ]

Recently, Weinstein finds some affinoids in the Lubin-Tate perfectoid space and computes their reduction in equal characteristic case. The cohomology of the reduction realizes the local Langlands correspondence for some representations of GL_h, which are unramified in some sense. In this talk, we introduce other affinoids in the Lubin-Tate perfectoid space in equal characteristic case, whose reduction realizes "ramified" representations of conductor exponent h+1. We call them ramified affinoids. We study the cohomology of the reduction and its relation with the local Langlands correspondence. This is a joint work with Takahiro Tsushima.

Recently, Weinstein finds some affinoids in the Lubin-Tate perfectoid space and computes their reduction in equal characteristic case. The cohomology of the reduction realizes the local Langlands correspondence for some representations of GL_h, which are unramified in some sense. In this talk, we introduce other affinoids in the Lubin-Tate perfectoid space in equal characteristic case, whose reduction realizes "ramified" representations of conductor exponent h+1. We call them ramified affinoids. We study the cohomology of the reduction and its relation with the local Langlands correspondence. This is a joint work with Takahiro Tsushima.

#### Kavli IPMU Komaba Seminar

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

Calabi-Yau threefolds of Type K (ENGLISH)

**Atsushi Kanazawa**(University of British Columbia)Calabi-Yau threefolds of Type K (ENGLISH)

[ Abstract ]

We will provide a full classification of Calabi-Yau threefolds of Type

K studied by Oguiso and Sakurai. Our study completes the

classification of Calabi-Yau threefolds with infinite fundamental

group. I will then discuss special Lagrangian T3-fibrations of

Calabi-Yau threefolds of type K. This talk is based on a joint work

with Kenji Hashimoto.

We will provide a full classification of Calabi-Yau threefolds of Type

K studied by Oguiso and Sakurai. Our study completes the

classification of Calabi-Yau threefolds with infinite fundamental

group. I will then discuss special Lagrangian T3-fibrations of

Calabi-Yau threefolds of type K. This talk is based on a joint work

with Kenji Hashimoto.

### 2013/04/23

#### Numerical Analysis Seminar

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

Pressure-stabilized characteristics finite element schemes for flow problems (JAPANESE)

[ Reference URL ]

http://www.infsup.jp

**Hirofumi Notsu**(Waseda Institute for Advanced Study)Pressure-stabilized characteristics finite element schemes for flow problems (JAPANESE)

[ Reference URL ]

http://www.infsup.jp

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