## Seminar information archive

#### GCOE Seminars

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

### 2013/10/16

#### Number Theory Seminar

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

#### Operator Algebra Seminars

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

#### Seminar on Probability and Statistics

13:30-14:40   Room #052 (Graduate School of Math. Sci. Bldg.)
NAKATANI, Tomoaki (Hokkaido University)

[ 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.)
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.

### 2013/10/12

#### Harmonic Analysis Komaba Seminar

13:00-18:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Tomoya Kato (Nagoya University) 13:30-15:00
The global Cauchy problems for nonlinear dispersive equations on modulation spaces
(JAPANESE)
Naoto Kumanogo (Kogakuin University) 15:30-17:00
Path 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.)
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)
[ 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.

### 2013/10/08

#### Tuesday Seminar on Topology

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

### 2013/10/07

#### Seminar on Geometric Complex Analysis

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

### 2013/10/03

#### Geometry Colloquium

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

### 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)

### 2013/10/01

#### Tuesday Seminar on Topology

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

### 2013/09/10

#### Monthly Seminar on Arithmetic of Automorphic Forms

13:30-15:00   Room #123 (Graduate School of Math. Sci. Bldg.)
Yuval Flicker (Ohio State Univ.) 13:30-15:00
Counting automorphic representations (JAPANESE)
Yuval Flicker (Ohio State University) 13:30-15:00
Counting automorphic representations II (Sept. 17) (JAPANESE)

### 2013/09/07

#### FMSP Lectures

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

### 2013/08/12

#### Operator Algebra Seminars

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

### 2013/07/29

#### Mathematical Biology Seminar

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

#### Colloquium

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

### 2013/07/25

#### thesis presentations

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