Seminar information archive

Seminar information archive ~05/28Today's seminar 05/29 | Future seminars 05/30~

thesis presentations

17:00-18:10   Room #122 (Graduate School of Math. Sci. Bldg.)
清野和彦 (東京大学大学院数理科学研究科)
Finite group actions on spin 4-manifolds(四次元スピン多様体への有限群作用)

2009/02/14

Infinite Analysis Seminar Tokyo

10:30-14:00   Room #117 (Graduate School of Math. Sci. Bldg.)
藤健太 (神戸理) 10:30-11:30
野海・山田系におけるタウ関数の関係式
[ Abstract ]
野海・山田系は, A型のドリンフェルト・ソコロフ階層の相似簡約から得られる高階
の常微分方程式系である.
本講演では, ドリンフェルト・ソコロフ階層を波動作用素を用いて考察することによっ
て, 野海・山田系のタウ関数の双線形方程式を求める.
鈴木貴雄 (神戸理) 13:00-14:00
ワイル群の regular な共役類に付随するドリンフェルト・ソコロフ階層とパンルヴェ型微分方程式
[ Abstract ]
ドリンフェルト・ソコロフ階層はKdV階層のアフィン・リー代数への一般化で, ワイ
ル群の共役類(またはハイゼンベルグ部分代数)によって特徴付けられる可積分系で
ある.
本講演では, ワイル群の共役類のうち特に regular と呼ばれるものに注目し, それ
に対応するドリンフェルト・ソコロフ階層の定式化について, F.Kroode-J.Leur, Kik
uchi-Ikeda-Kakei 等の仕事を紹介しつつ解説する.
また, パンルヴェ型微分方程式との関連についても述べる.

2009/02/13

GCOE lecture series

15:00-16:00   Room #370 (Graduate School of Math. Sci. Bldg.)
Vladimir Romanov (Sobolev Instutite of Mathematics)
ASYMPTOTIC EXPANSIONS FOR SOME HYPERBOLIC EQUATIONS 第3講
[ Abstract ]
For a linear second-order hyperbolic equation with variable coefficients the fundamental solution for the Cauchy problem is considered. An asymptotic expansion of this solution in a neighborhood of the characteristic cone is introduced and explicit formulae for coefficients of this expansion are derived. Similar questions are discussed for the elasticity equations related to an inhomogeneous isotropic medium.

GCOE Seminars

14:00-14:45   Room #270 (Graduate School of Math. Sci. Bldg.)
Johannes Elschner (Weierstrass Institute)
Direct and inverse problems in fluid-solid interaction
[ Abstract ]
We consider the interaction between an elastic body and a compressible inviscid fluid, which occupies the unbounded exterior domain. The direct problem is to determine the scattered pressure field in the fluid domain as well as the displacement field in the elastic body, while the inverse problem is to reconstruct the shape of the elastic body from the far field pattern of the fluid pressure. We present a variational approach to the direct problem and two reconstruction methods for the inverse problem, which are based on nonlinear optimization and regularization.

GCOE Seminars

16:15-17:00   Room #270 (Graduate School of Math. Sci. Bldg.)
Wenbin Chen (Fudan University)
New Energy-conserved Splitting Finite-Difference Time-Domain Methods for Maxwell's Equations
[ Abstract ]
In this talk, two new energy-conserved splitting methods (EC-S-FDTDI and EC-S-FDTDII) for Maxwell’s equations are proposed. Both algorithms are energy-conserved, unconditionally stable and can be computed efficiently. The convergence results are analyzed based on the energy method, which show that the EC-S-FDTDI scheme is of first order in time and of second order in space, and the EC-S-FDTDII scheme is of second order both in time and space. We also obtain two identities of the discrete divergence of electric fields for these two schemes. For the EC S-FDTDII scheme, we prove that the discrete divergence is of first order to approximate the exact divergence condition. Numerical dispersion analysis shows that these two schemes are non-dissipative. Numerical experiments confirm well the theoretical analysis results.

2009/02/12

Lectures

17:00-18:30   Room #056 (Graduate School of Math. Sci. Bldg.)
Freddy DELBAEN (チューリッヒ工科大学名誉教授)
Introduction to Coherent Risk Measure

2009/02/10

GCOE Seminars

15:00-16:00   Room #270 (Graduate School of Math. Sci. Bldg.)
Piermarco Cannarsa (Univ. degli Studi Roma "Tor Vergata")
Carleman estimates for degenerate parabolic operators with application to null controllability
[ Abstract ]
From the controllability viewpoint, the behavior of uniformly parabolic equations is by now well understood. On the contrary, fewer results are known for degenerate parabolic equations, even though such a class of operators arise in many applied, as well as theoretical, problems.

A fairly complete analysis of the null controllability properties of degenerate parabolic equations in one space dimension was completed in a series of recent works by the speaker and coauthors. The aim of this talk is to review the above theory and present some recent results obtained in collaboration with P. Martinez and J.Vancostenoble for higher dimensional problems. Essential tools of such an approach are adapted Carleman estimates and Hardy type inequalities.

GCOE Seminars

16:15-17:15   Room #270 (Graduate School of Math. Sci. Bldg.)
Yurii Anikonov (Sobolev Institute of Mathematics)
Constructive methods in inverse problems
[ Abstract ]
New representations for solutions and coefficients of evolutionary equations are presented. On the basic of these representations theorems of solvability for inverse problems are obtained. This direction develops constructibility in the theory and applications of inverse problems to differential equations

2009/02/07

Monthly Seminar on Arithmetic of Automorphic Forms

13:30-16:00   Room #123 (Graduate School of Math. Sci. Bldg.)
河村隆 (成蹊大学) 13:30-14:30
次数2のモジュラー群の基本領域における行列式の最小値
早田孝博 (山形大学・工学部) 15:00-16:00
Siegel's fundamental domain of degree 2 and Groebner method

2009/02/06

GCOE lecture series

15:00-16:00   Room #370 (Graduate School of Math. Sci. Bldg.)
Vladimir Romanov (Sobolev Instutite of Mathematics)
ASYMPTOTIC EXPANSIONS FOR SOME HYPERBOLIC EQUATIONS 第2講
[ Abstract ]
For a linear second-order hyperbolic equation with variable coefficients the fundamental solution for the Cauchy problem is considered. An asymptotic expansion of this solution in a neighborhood of the characteristic cone is introduced and explicit formulae for coefficients of this expansion are derived. Similar questions are discussed for the elasticity equations related to an inhomogeneous isotropic medium.

thesis presentations

09:45-11:00   Room #118 (Graduate School of Math. Sci. Bldg.)
中岡 宏行 (東京大学大学院数理科学研究科)
Brauer Groups,Mackey and Tambara functors on profinite groups,and 2-dimensional homological algebra(Brauer群、プロ有限群上のMackey及び丹原関手と2次元ホモロジー代数)

thesis presentations

11:00-12:15   Room #118 (Graduate School of Math. Sci. Bldg.)
廣惠 一希 (東京大学大学院数理科学研究科)
Generalized Whittaker functions for degenerate principal series of GL(4,R)(GL(4,R)の退化主系列表現の一般Whittaker関数)

thesis presentations

13:00-14:15   Room #118 (Graduate School of Math. Sci. Bldg.)
阿部 紀行 (東京大学大学院数理科学研究科)
On the existence of homomorphisms between principal series of complex semisimple Lie groups(複素半単純リー群の主系列表現の間の準同型の存在について)

thesis presentations

11:00-12:15   Room #122 (Graduate School of Math. Sci. Bldg.)
中村 伊南沙 (東京大学大学院数理科学研究科)
Surface links which are coverings of a trivial torus knot(自明なトーラスの被覆の形をした曲面結び目の研究)

thesis presentations

13:00-14:15   Room #122 (Graduate School of Math. Sci. Bldg.)
山下 温 (東京大学大学院数理科学研究科)
Compactification of the homeomorphism group of a graph(グラフの同相群のコンパクト化について)

thesis presentations

09:45-11:00   Room #126 (Graduate School of Math. Sci. Bldg.)
乙部 達志 (東京大学大学院数理科学研究科)
Large deviations and theorems of law of large numbers' type for the processes related to the interface models(
界面モデルに関連した確率過程に対する大偏差原理と大数の法則型極限定理)

thesis presentations

13:00-14:15   Room #126 (Graduate School of Math. Sci. Bldg.)
米田 剛 (東京大学大学院数理科学研究科)
On the Navier-Stokes equations in a rotating frame and the functional-differential equations of advanced type - a Fourier analysis approach(フーリエ解析的手法による回転場内の流体方程式と進み型関数微分方程式の考察)

thesis presentations

11:00-12:15   Room #128 (Graduate School of Math. Sci. Bldg.)
野田 秀明 (東京大学大学院数理科学研究科)
Short time asymptotic behavior and large deviations for Brownian motion on scale irregular Sierpinski gaskets(非正規なシェルピンスキーガスケット上のブラウン運動に対する熱核の短時間漸近挙動と大偏差原理)

thesis presentations

13:00-14:15   Room #128 (Graduate School of Math. Sci. Bldg.)
河内 一樹 (東京大学大学院数理科学研究科)
Rumor Transmission Models and Persistence Analysis(流言伝播モデルとパーシステンス解析)

thesis presentations

14:15-15:30   Room #128 (Graduate School of Math. Sci. Bldg.)
川上 拓志 (東京大学大学院数理科学研究科)
Generalized Okubo systems and the middle convolution(一般大久保型方程式とミドルコンボルーション)

GCOE Seminars

16:15-17:00   Room #370 (Graduate School of Math. Sci. Bldg.)
G. Yuan (Northeast Normal Univ.)
Inverse problems and observability inequalities for plate equations and Schrodinger equations.
[ Abstract ]
In this talk, we will present some results on inverse problems and observability inequalities for some plate and Schrodinger equaions by using several kinds of Carleman estimates.

2009/02/05

Lectures

17:00-18:30   Room #117 (Graduate School of Math. Sci. Bldg.)
Freddy DELBAEN (チューリッヒ工科大学名誉教授)
Introduction to Coherent Risk Measure

Applied Analysis

16:00-17:30   Room #002 (Graduate School of Math. Sci. Bldg.)
Jin CHENG (程 晋) (復旦大学)
Heat transfer in composite materials with Stenfen-Boltzmann conditions and related inverse problems
[ Abstract ]
In this talk, we will present our recent results on the mathematical model of the heat transfer in the composite materials. The related inverse problems are discussed. The numerical results show our methods are effective.

thesis presentations

15:45-17:00   Room #118 (Graduate School of Math. Sci. Bldg.)
GOMBODORJ BAYARMAGNAI (東京大学大学院数理科学研究科)
THE(g,K)-MODULE STRUCTURE OF PRINCIPAL SERIES AND RELATED WHITTAKER FUNCTIONS OF SU(2,2)(SU(2,2)の主系列の(g,K)-加群構造と関連するWHITTAKER関数)

thesis presentations

11:00-12:15   Room #126 (Graduate School of Math. Sci. Bldg.)
関 行宏 (東京大学大学院数理科学研究科)
On behavior of solutions near singularities for nonlinear diffusion equations(非線形拡散方程式の特異点近くでの解の挙動)

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