Seminar information archive

Seminar information archive ~02/25Today's seminar 02/26 | Future seminars 02/27~

thesis presentations

9:15-10:30   Room #122 (Graduate School of Math. Sci. Bldg.)
間瀬 崇史 (東京大学大学院数理科学研究科)
Studies on spaces of initial conditions for nonautonomous mappings of the plane and singularity confinement(平面上の非自励写像に対する初期値空間と特異点閉じ込めの研究) (JAPANESE)

thesis presentations

10:45-12:00   Room #122 (Graduate School of Math. Sci. Bldg.)
佐々木 多希子 (東京大学大学院数理科学研究科)
Numerical and mathematical analysis for blow-up phenomena to nonlinear wave equations(非線形波動方程式の爆発現象に関する数値・数学解析) (JAPANESE)

thesis presentations

12:45-14:00   Room #122 (Graduate School of Math. Sci. Bldg.)
李 志遠 (東京大学大学院数理科学研究科)
Mathematical analysis for diffusion equations with generalized fractional time derivatives (一般化された非整数階時間微分項を持つ拡散方程式に対する数学解析について) (JAPANESE)

thesis presentations

9:15-10:30   Room #126 (Graduate School of Math. Sci. Bldg.)
寺門 康裕 (東京大学大学院数理科学研究科)
The determinant and the discriminant of a complete intersection of even dimension(偶数次元完全交叉の行列式と判別式) (JAPANESE)

thesis presentations

10:45-12:00   Room #126 (Graduate School of Math. Sci. Bldg.)
大川 幸男 (東京大学大学院数理科学研究科)
Riemann-Hilbert correspondence for unit F-crystals on embeddable algebraic varieties(埋め込み可能な代数多様体上のユニットF-クリスタルに対するリーマン-ヒルベルト対応) (JAPANESE)

thesis presentations

12:45-14:00   Room #126 (Graduate School of Math. Sci. Bldg.)
渡部 正樹 (東京大学大学院数理科学研究科)
Schubert polynomials,Kraśkiewicz-Pragacz modules and highest weight categories(Schubert 多項式,Kraśkiewicz-Pragacz 加群と最高ウェイト圏) (JAPANESE)

2016/01/28

thesis presentations

11:00-12:15   Room #118 (Graduate School of Math. Sci. Bldg.)
大久保 直人 (東京大学大学院数理科学研究科)
Discrete integrable equations associated with cluster algebra and its extension(クラスター代数およびその拡張に付随する離散可積分方程式) (JAPANESE)

thesis presentations

13:00-14:15   Room #118 (Graduate School of Math. Sci. Bldg.)
鈴木 悠平 (東京大学大学院数理科学研究科)
Constructions of amenable dynamical systems and its applications to nuclearity of C*-algebras(従順位相力学系の構成とC*環の核型性への応用) (JAPANESE)

thesis presentations

14:30-15:45   Room #118 (Graduate School of Math. Sci. Bldg.)
嶌田 洸一
Actions of locally compact abelian groups on factors with the Rohlin property(ロホリン性をもつ局所コンパクト可換群の因子環へ作用) (JAPANESE)

thesis presentations

16:00-17:15   Room #118 (Graduate School of Math. Sci. Bldg.)
武石 拓也 (東京大学大学院数理科学研究科)
Primitive ideals of Bost-Connes systems(ボスト・コンヌ系の原始イデアルについて) (JAPANESE)

thesis presentations

9:30-10:45   Room #122 (Graduate School of Math. Sci. Bldg.)
甲斐 亘 (東京大学大学院数理科学研究科)
A moving lemma for algebraic cycles with modulus and contravariance(モジュラス付き代数的サイクルの移動補題と引き戻し写像) (JAPANESE)

thesis presentations

11:00-12:15   Room #122 (Graduate School of Math. Sci. Bldg.)
谷田川 友里 (東京大学大学院数理科学研究科)
Characteristic cycle and ramification of a rank 1 sheaf(階数 1 の層の特性サイクルと分岐) (JAPANESE)

thesis presentations

13:00-14:15   Room #122 (Graduate School of Math. Sci. Bldg.)
時本 一樹 (東京大学大学院数理科学研究科)
Affinoids in the Lubin-Tate perfectoid space and special cases of the local Langlands correspondence in positive characteristic(Lubin-Tate perfectoid 空間のアフィノイドと正標数の局所Langlands 対応の特別な場合について) (JAPANESE)

thesis presentations

16:00-17:15   Room #122 (Graduate School of Math. Sci. Bldg.)
川節 和哉 (東京大学大学院数理科学研究科)
W-algebras, free vertex algebras, and the Deligne exceptional series(W 代数, 自由な頂点代数とドリーニュの例外系列) (JAPANESE)

thesis presentations

9:30-10:45   Room #126 (Graduate School of Math. Sci. Bldg.)
松下 尚弘 (東京大学大学院数理科学研究科)
Hom complexes and chromatic numbers of graphs(グラフのHom複体と彩色数について) (JAPANESE)

thesis presentations

11:00-12:15   Room #126 (Graduate School of Math. Sci. Bldg.)
川﨑 盛通 (東京大学大学院数理科学研究科)
(JAPANESE)

thesis presentations

13:00-14:15   Room #126 (Graduate School of Math. Sci. Bldg.)
角田 謙吉 (東京大学大学院数理科学研究科)
Derivation of Stefan problem and large deviation principles for lattice-gas(格子気体に対するステファン問題の導出と大偏差原理) (JAPANESE)

thesis presentations

14:30-15:45   Room #126 (Graduate School of Math. Sci. Bldg.)
Nguyen Duc Tam (ベトナム科学技術アカデミー数学研究所)
Combinatorics of jet schemes and its applications(ジェットスキームの組み合わせ論とその応用) (ENGLISH)

thesis presentations

16:00-17:15   Room #126 (Graduate School of Math. Sci. Bldg.)
柴田 康介 (東京大学大学院数理科学研究科)
Rational singularities,ω-multiplier ideals and core of ideals(有理特異点、ω-乗数イデアルとイデアルのコア) (JAPANESE)

thesis presentations

14:30-15:45   Room #122 (Graduate School of Math. Sci. Bldg.)
丸亀 泰二 (東京大学大学院数理科学研究科)
Volume renormalization for the Blaschke metric on strictly convex domains (強凸領域上のブラシュケ計量の体積繰り込みについて) (JAPANESE)

2016/01/27

Seminar on Probability and Statistics

13:00-14:10   Room #052 (Graduate School of Math. Sci. Bldg.)
Ajay Jasra (National University of Singapore)
Multilevel SMC Samplers
[ Abstract ]

The approximation of expectations w.r.t. probability distributions associated to the solution of partial differential equations (PDEs) is considered herein; this scenario appears routinely in Bayesian inverse problems. In practice, one often has to solve the associated PDE numerically, using, for instance finite element methods and leading to a discretisation bias, with step-size level h_L. In addition, the expectation cannot be computed analytically and one often resorts to Monte Carlo methods. In the context of this problem, it is known that the introduction of the multi-level Monte Carlo (MLMC) method can reduce the amount of computational effort to estimate expectations, for a given level of error. This is achieved via a telescoping identity associated to a Monte Carlo approximation of a sequence of probability distributions with discretisation levels \infty>h_0>h_1\cdots>h_L. In many practical problems of interest, one cannot achieve an i.i.d. sampling of the associated sequence of probability distributions. A sequential Monte Carlo (SMC) version of the MLMC method is introduced to deal with this problem. It is shown that under appropriate assumptions, the attractive property of a reduction of the amount of computational effort to estimate expectations, for a given level of error, can be maintained in the SMC context. The approach is numerically illustrated on a Bayesian inverse problem. This is a joint work with Kody Law (ORNL), Yan Zhou (NUS), Raul Tempone (KAUST) and Alex Beskos (UCL).

Mathematical Biology Seminar

13:30-16:30   Room #128 (Graduate School of Math. Sci. Bldg.)
Shinji Nakaoka (Graduate School of Medicine, The University of Tokyo) 15:10-15:50
Mathematical analysis for HIV infection dynamics in lymphoid tissue network (JAPANESE)
Hideki Sano (Graduate School of System Informatics, Kobe University) 13:30-14:10
On approximation of stability radius for an infinite-dimensional closed-loop control system
(JAPANESE)
[ Abstract ]
We discuss the problem of approximating stability radius appearing
in the design procedure of finite-dimensional stabilizing controllers
for an infinite-dimensional dynamical system. The calculation of
stability radius needs the value of the H-infinity norm of a transfer
function whose realization is described by infinite-dimensional
operators in a Hilbert space. From the practical point of view, we
need to prepare a family of approximate finite-dimensional operators
and then to calculate the H-infinity norm of their transfer functions.
However, it is not assured that they converge to the value of the
H-infinity norm of the original transfer function. The purpose of
this study is to justify the convergence. In a numerical example,
we treat parabolic distributed parameter systems with distributed
control and distributed/boundary observation.

Toshikazu Kiniya (Graduate School of System Informatics, Kobe University) 14:10-14:50
Prediction of the increase or decrease of infected population based on the backstepping method
(JAPANESE)
Takaaki Funo (Faculty of science, Kyushu University) 15:50-16:30
Mathematical model of malaria spread for a village network

2016/01/26

PDE Real Analysis Seminar

10:30-11:30   Room #056 (Graduate School of Math. Sci. Bldg.)
Salomé Oudet (University of Tokyo)
Hamilton-Jacobi equations for optimal control on 2-dimensional junction (English)
[ Abstract ]
We are interested in infinite horizon optimal control problems on 2-dimensional junctions (namely a union of half-planes sharing a common straight line) where different dynamics and different running costs are allowed in each half-plane. As for more classical optimal control problems, ones wishes to determine the Hamilton-Jacobi equation which characterizes the value function. However, the geometric singularities of the 2-dimensional junction and discontinuities of data do not allow us to apply the classical results of the theory of the viscosity solutions.
We will explain how to skirt these difficulties using arguments coming both from the viscosity theory and from optimal control theory. By this way we prove that the expected equation to characterize the value function is well posed. In particular we prove a comparison principle for this equation.

2016/01/25

Tokyo Probability Seminar

16:50-18:20   Room #128 (Graduate School of Math. Sci. Bldg.)
Atsushi Nakayasu (Graduate School of Mathematical Sciences, The University of Tokyo)
Hamilton-Jacobi equations in metric spaces

Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Kunio Obitsu (Kagoshima Univ.)
(Japanese)

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