Seminar information archive

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



10:30-17:20   Room #123 (Graduate School of Math. Sci. Bldg.)
Erwin Bolthausen (University of Zurich) 10:30-12:00
Exit distributions for random walks in random environments
Erwin Bolthausen (University of Zurich) 14:00-15:30
Quasi one-dimensional random walks in random environments
田村要造 (慶応大理工) 15:50-16:30
Large deviation principle for currents generated by stochasticline integrals
on compact Riemannian manifolds (joint work with S. Kusuoka and K. Kuwada)
長田博文 (九大数理) 16:40-17:20
Interacting Brownian motions related to Ginibre random point field

Tuesday Seminar of Analysis

16:30-18:00   Room #117 (Graduate School of Math. Sci. Bldg.)
Patrick G¥'erard (パリ南大学)
On the dynamics of the Gross-Pitaevskii equation


Infinite Analysis Seminar Tokyo

13:30-16:00   Room #117 (Graduate School of Math. Sci. Bldg.)
阿部 友紀 (上智理工数学) 13:30-14:30
Finite-dimensional representations of the small quantum algebras
[ Abstract ]
De Conini-Kac氏らによって定義された「非制限型量子代数」の2種類が存在し、
また、制限型量子代数は、「小型量子代数(=small quantum algebra)」と

●A, B, C, D, G型の小型量子代数の有限次元既約表現を、
Seok-Jin Kang (Seoul National University) 15:00-16:00
Combinatorics of Young walls and crystal bases
[ Abstract ]
We introduce combinatorics of Young walls and give a realization of crystal bases in terms of reduced Young walls. We also discuss their connection with representation theory of Hecke algebras.



16:30-17:30   Room #123 (Graduate School of Math. Sci. Bldg.)
松本幸夫 (東京大学・大学院数理科学研究科)
[ Abstract ]

Applied Analysis

15:00-16:00   Room #056 (Graduate School of Math. Sci. Bldg.)
Ratnasingham SHIVAJI (ミシシッピ州立大学)
Multiple positive solutions for classes of elliptic systems with combined nonlinear effects
[ Abstract ]
We study the existence of multiple positive solutions to systems of the form

-\\Delta u = \\lambda f(v)
-\\Delta v = \\lambda g(u)

in a bounded domain in R^N under the Dirichlet boundary conditions. Here f, g belong to a class of positive functions having a combined sublinear effect at infinity. Our result also easily extends to the corresponding p-Laplacian systems. We prove our results by the method of sub and super solutions.



15:00-16:00   Room #118 (Graduate School of Math. Sci. Bldg.)
Lassi Paivarinta (Helsinki University of Technology, Finland)
On Calderon's inverse conductivity problem in the plane.


16:15-17:15   Room #118 (Graduate School of Math. Sci. Bldg.)
Nuuti Huyvonen (Helsinki University of Technology,
Locating transparent cavities in optical absorption and scattering


Seminar on Mathematics for various disciplines

10:30-11:30   Room #123 (Graduate School of Math. Sci. Bldg.)
小谷正博 (学習院大学)
[ Abstract ]


[ Reference URL ]

Number Theory Seminar

15:15-18:45   Room #117 (Graduate School of Math. Sci. Bldg.)
Dennis Eriksson (東大数理/Paris) 15:15-16:15
Towards a proof of a metrized Deligne-Riemann-Roch theorem
小林 真一 (名古屋大学多元数理) 16:30-17:30
(A two variable p-adic L-function for CM elliptic curves at supersingular primes)
Frans Oort (Utrecht) 17:45-18:45
Irreducibility of strata and leaves in the moduli space of abelian varieties


16:30-18:00   Room #126 (Graduate School of Math. Sci. Bldg.)
Li Daqian (復旦大学)
Exact Controllability and Exact Observability for Quasilinear Hyperbolic Systems

Seminar on Probability and Statistics

16:20-17:30   Room #128 (Graduate School of Math. Sci. Bldg.)
西山 慶彦 (京都大学経済研究所)
A Sequential Unit Root Test
[ Abstract ]
It is well known that conventional unit root tests such as Dickey=Fuller and its variants do not have good power properties when sample size is not large. Lai and Siegmund (1983, AS) proved that OLS estimator of the AR(1) coefficient is asymptotically normally distributed in a sequential framework even if the time series has a unit root unlike the OLS estimator under a standard sampling scheme. We pursue this direction to propose a unit root test under a sequential sampling. The proposed test uses not only the OLS estimator of the AR(1) coefficient, which is asymptotically normal, but also the stopping time to construct the critical region, anticipating a better power property. We obtain analytic expressions of the joint distribution of the two statistics as well as its marginals under the null. We also consider the distribution of the statistics under local alternatives. The properties of the stopping time, to the best of our knowledge, have not been studied in the unit root literature. We calculate its expectation and variance.
[ Reference URL ]


Tuesday Seminar on Topology

16:30-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
John F. Duncan (Harvard University)
Elliptic genera and some finite groups
[ Abstract ]
Recent developments in the representation theory of sporadic groups
suggest new formulations of `moonshine' in which Jacobi forms take on the
role played by modular forms in the monstrous case. On the other hand,
Jacobi forms arise naturally in the study of elliptic genera. We review
the use of vertex algebra as a tool for constructing the elliptic genus of
a suitable vector bundle, and illustrate connections between this and
vertex algebraic representations of certain sporadic simple groups.


16:30-18:00   Room #118 (Graduate School of Math. Sci. Bldg.)
Jerome Le Rousseau (Laboratoire d'Analyse Topologie Probabilit\'es
Universit\'e de Provence / CNRS)
Controllability of parabolic equations with non-smooth coefficients by means of global Carleman estimates
[ Abstract ]
We shall review the different concepts of controllability for parabolic equations and a fix-point method to achieve null-controllability of classes of semilinear equations. It is mainly based on observability inequalities and a precise knowledge of the observability constant. These inequalities are obtained by means of global Carleman estimates. We shall review their derivations and how they can be obtained in the case of non-smooth coefficients. We shall also present some open questions.
Part of this work is in collaboration with Assia Benabdallah and Yves Dermenjian (also from Universit\\'e de Provence).

Infinite Analysis Seminar Tokyo

14:00-15:00   Room #123 (Graduate School of Math. Sci. Bldg.)
Michael Lashkevich (Landau Institute)
Scaling limits for the SOS models and bosonization
[ Abstract ]
Two different scaling limits in the SOS models are considered. The scaling limits of the bosonic construction for form factors provide form factors of some classes of operators in the scaling SOS/RSOS models and the sine-Gordon model.



16:30-18:00   Room #126 (Graduate School of Math. Sci. Bldg.)
Li Daqian (復旦大学)
Exact Controllability and Exact Observability for Quasilinear Hyperbolic Systems

Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
松島敏夫 (石川工業高専)
Radial cluster set of a bounded holomorphic map in the unit ball of C^n


Infinite Analysis Seminar Tokyo

13:30-16:00   Room #117 (Graduate School of Math. Sci. Bldg.)
清水 寧 (立命館理工物理) 13:30-14:30
[ Abstract ]
山田 大輔 (東大数理) 15:00-16:00
[ Abstract ]


この問題にアプローチするために、キリロフ・レシェティヒン加群$W_s^{(r)}$ (以下略してKR加群)を研究したい。これはアフィンリー環のディンキン図形の頂点$0$を除く頂点の番号$r$と、任意の正整数$s$の組によってパラメトライズされる。KR加群に関して、``フェルミ型公式''に起源をもつ以下の予想がある。尚, 現在までにこの予想の反例は見つかっていない。

さらに$s$が$t_r:=max(1,2/(\\alpha_r \\vert \\alpha_r))$の倍数ならば、KR加群$W_s^{(r)}$の結晶基底$B^{r,s}$は、レベル$s/t_r$の完全結晶である。ただし, $(\\cdot \\vert \\cdot)$はウェイト格子上の標準線形形式。」

我々は, 例外型アフィンリー環$D_4^{(3)}$のKR加群$W_s^{(1)}$と$W_1^{(2)}$について、上の予想が正しいことを示した。その応用として、超離散可積分系の重要な例である「箱玉系」を構成し、そこに現れるソリトンの散乱則を表現論的に記述した。



Algebraic Geometry Seminar

16:30-17:30   Room #128 (Graduate School of Math. Sci. Bldg.)
Professor Frans Oort
(Department of Mathematics
University of Utrecht
Irreducibility of strata and leaves in the moduli space of
abelian varieties I (a survey of results)


16:30-18:00   Room #126 (Graduate School of Math. Sci. Bldg.)
Li Daqian (復旦大学)
Controllability and Observability:
from ODEs to Quasilinear Hyperbolic Systems


Applied Analysis

16:00-17:30   Room #056 (Graduate School of Math. Sci. Bldg.)
Michael TRIBELSKY (東大・数理 / モスクワ工科大学)
Soft-mode turbulence as a new type of spatiotemporal chaos at onset

Operator Algebra Seminars

15:15-18:00   Room #126 (Graduate School of Math. Sci. Bldg.)
澤田恒河 (東大数理) 15:15-16:15
The Pimsner-Voiculescu AF-embedding of the irrational rotation $C^*$-algebra and its subalgebra
水田有一 (東大数理) 16:30-18:00
A Note on Weak Amenability

Functional Analysis Seminar

14:00-17:00   Room #370 (Graduate School of Math. Sci. Bldg.)
Ivana Alexandrova (East Carolina University)
Semi-Classical Structure of the Scattering Amplitude and the Spectral Function for Schrodinger Operators


Tuesday Seminar on Topology

16:30-18:30   Room #056 (Graduate School of Math. Sci. Bldg.)
中田 文憲 (東京大学大学院数理科学研究科) 16:30-17:30
The twistor correspondence for self-dual Zollfrei metrics
----their singularities and reduction

[ Abstract ]
C. LeBrun and L. J. Mason investigated a twistor-type correspondence
between indefinite conformal structures of signature (2,2) with some properties
and totally real embeddings from RP^3 to CP^3.
In this talk, two themes following LeBrun and Mason are explained.

First we consider an additional structure:
the conformal structure is equipped with a null surface foliation
which has some singularity.
We establish a global twistor correspondence for such structures,
and we show that a low dimensional correspondence
between some quotient spaces is induced from this twistor correspondence.

Next we formulate a certain singularity for the conformal structures.
We generalize the formulation of LeBrun and Mason's theorem
admitting the singularity, and we show explicit examples.

大橋 了 (東京大学大学院数理科学研究科) 17:30-18:30
On the homology group of $Out(F_n)$
[ Abstract ]
Suppose $F_n$ is the free group of rank $n$,
$Out(F_n) = Aut(F_n)/Inn(F_n)$ the outer automorphism group of $F_n$.
We compute $H_*(Out(F_n);\\mathbb{Q})$ for $n\\leq 6$ and conclude
that non-trivial classes in this range are generated
by Morita classes $\\mu_i \\in H_{4i}(Out(F_{2i+2});\\mathbb{Q})$.
Also we compute odd primary part of $H^*(Out(F_4);\\mathbb{Z})$.


Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Hanjin Lee (Seoul National University)
Omori-Yau generalized maximum principle



10:30-12:00   Room #056 (Graduate School of Math. Sci. Bldg.)
Alex Mahalov (Arizona State University)
3D Navier-Stokes and Euler Equations with Uniformly Large Initial Vorticity: Global Regularity and Three-Dimensional Euler Dynamics

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