過去の記録

過去の記録 ~08/21本日 08/22 | 今後の予定 08/23~

博士論文発表会

13:00-14:15   数理科学研究科棟(駒場) 122号室
深澤 正彰 氏 (大阪大学 金融・保険教育研究センター)
Asymptotic Analysis for Stochastic Volatility (確率的ボラティティの漸近解析)

2009年10月21日(水)

GCOEレクチャーズ

15:30-17:00   数理科学研究科棟(駒場) 122号室
Jean-Dominique Deuschel 氏 (TU Berlin)
Mini course on the gradient models, Ⅲ: Non convex potentials at high temperature
[ 講演概要 ]
In the non convex case, the situation is much more complicated. In fact Biskup and Kotecky describe a non convex model with several ergodic components. We investigate a model with non convex interaction for which unicity of the ergodic component, scaling limits and large deviations can be proved at sufficiently high temperature. We show how integration can generate strictly convex potential, more precisely that marginal measure of the even sites satisfies the random walk representation. This is a joint work with Codina Cotar and Nicolas Petrelis.

代数学コロキウム

16:30-17:30   数理科学研究科棟(駒場) 056号室
Bernard Le Stum 氏 (Université de Rennes 1)
The local Simpson correspondence in positive characteristic
[ 講演概要 ]
A Simpson correspondance should relate Higgs bundles to differential modules (or local systems). We stick here to positive characteristic and recall some old and recent results : Cartier isomorphism, Van der Put's classification, Kaneda's theorem and Ogus-Vologodsky local theory. We'll try to explain how the notion of Azumaya algebra is a convenient tool to unify these results. Our main theorem is the equivalence between quasi-nilpotent differential modules of level m and quasi-nilpotent Higgs Bundles (depending on a lifting of Frobenius mod p-squared). This result is a direct generalization of the previous ones. The main point is to understand the Azumaya nature of the ring of differential operators of level m. Following Berthelot, we actually use the dual theory and study the partial divided power neighborhood of the diagonal.

講演会

14:40-16:10   数理科学研究科棟(駒場) 128号室
竹崎正道 氏 (UCLA)
冨田竹崎理論とその応用 (2)

統計数学セミナー

15:00-16:10   数理科学研究科棟(駒場) 002号室
田中 冬彦 氏 (科学技術振興機構さきがけ)
AR過程の優調和事前分布と偏自己相関係数による表示
[ 講演概要 ]
Tanaka and Komaki(2008)では時系列データが2次の自己回帰過程(AR過程)に従う 時のスペクトル密度の推定を考え、優調和事前分布に基づいたベイズスペクトル 密度の方がジェフリーズ事前分布に基づいたベイズスペクトル密度よりも精度よ く推定できることを示している。高次のAR過程での優調和事前分布はTanaka( 2009)によって初めて与えられたが、特性方程式の根を用いた表示のため、数値 実験を行う上では取り扱いづらかった。本発表では高次のAR過程への応用を念頭 において偏自己相関係数(PAC)によるパラメータ表示を導入し数値実験した結 果を紹介する。 また、PACパラメータによる表示は解析的な取扱いをする上でも利点があり、AR 過程の優調和事前分布に関して新しく得られた結果も幾つか紹介したい。
[ 講演参考URL ]
http://www.ms.u-tokyo.ac.jp/~kengok/statseminar/2009/06.html

2009年10月20日(火)

トポロジー火曜セミナー

16:30-18:00   数理科学研究科棟(駒場) 056号室
Tea: 16:00 - 16:30 コモンルーム
吉田 尚彦 氏 (明治大学大学院理工学研究科)
Torus fibrations and localization of index
[ 講演概要 ]
I will describe a localization of index of a Dirac type operator.
We make use of a structure of torus fibration, but the mechanism
of the localization does not rely on any group action. In the case of
Lagrangian fibration, we show that the index is described as a sum of
the contributions from Bohr-Sommerfeld fibers and singular fibers.
To show the localization we introduce a deformation of a Dirac type
operator for a manifold equipped with a fiber bundle structure which
satisfies a kind of acyclic condition. The deformation allows an
interpretation as an adiabatic limit or an infinite dimensional analogue
of Witten deformation.

Joint work with Hajime Fujita and Mikio Furuta.

講演会

14:40-16:10   数理科学研究科棟(駒場) 128号室
竹崎正道 氏 (UCLA)
冨田竹崎理論とその応用 (1)

2009年10月19日(月)

複素解析幾何セミナー

10:30-12:00   数理科学研究科棟(駒場) 128号室
濱野佐知子 氏 (松江高専)
Variation formulas for principal functions (II)

代数幾何学セミナー

16:40-18:10   数理科学研究科棟(駒場) 126号室
渡辺 究 氏 (早稲田大学基幹理工学研究科)
ファノ多様体上の有理曲線の鎖の長さについて
[ 講演概要 ]
ピカール数1のファノ多様体に対し、一般の二点を結ぶために必要な
極小有理曲線の本数を「長さ」と呼び、それについて考える。特に、5次元以下の
ファノ多様体や余指数が3以下のファノ多様体などに対し、長さを求める。

2009年10月15日(木)

GCOE社会数理講演シリーズ

16:20-17:50   数理科学研究科棟(駒場) 056号室
講演曜日・場所が通常と異なりますのでご注意ください。
藤原 洋 氏 (インターネット総合研究所代表取締役所長)
社会における学位取得者の役割Ⅰ

Lie群論・表現論セミナー

16:30-18:00   数理科学研究科棟(駒場) 122号室
土岡俊介 氏 (RIMS, Kyoto University)
Hecke-Clifford superalgebras and crystals of type $D^{(2)}_{l}$
[ 講演概要 ]
It is known that we can sometimes describe the representation theory of ``Hecke algebra'' by ``Lie theory''. Famous examples that involve the Lie theory of type $A^{(1)}_n$ are Lascoux-Leclerc-Thibon's interpretation of Kleshchev's modular branching rule for the symmetric groups and Ariki's theorem generalizing Lascoux-Leclerc-Thibon's conjecture for the Iwahori-Hecke algebras of type A.

Brundan and Kleshchev showed that some parts of the representation theory of the affine Hecke-Clifford superalgebras and its finite-dimensional ``cyclotomic'' quotients are controlled by the Lie theory of type $A^{(2)}_{2l}$ when the quantum parameter $q$ is a primitive $(2l+1)$-th root of unity.
In this talk, we show that similar theorems hold when $q$ is a primitive $4l$-th root of unity by replacing the Lie theory of type $A^{(2)}_{2l}$ with that of type $D^{(2)}_{l}$.
[ 講演参考URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

2009年10月14日(水)

GCOEレクチャーズ

15:30-17:00   数理科学研究科棟(駒場) 128号室
Claudio Landim 氏 (IMPA, Brazil)
Macroscopic fluctuation theory for nonequilibrium stationary states, Ⅳ

GCOEレクチャーズ

13:30-15:00   数理科学研究科棟(駒場) 128号室
Jean-Dominique Deuschel 氏 (TU Berlin)
Mini course on the gradient models, Ⅱ: Convex interaction potential
[ 講演概要 ]
Much is known for strictly convex interactions, which under rescaling behave much like the harmonic model. In particular the unicity of the ergodic component have been established by Funaki and Spohn, and the scaling limit to the gradient of the continuous gaussian free field by Naddaf and Spencer. The results are based on special analytical and probabilistic tools such as the Brascamp-Lieb inequality and the Hellfer-Sj\\"osstrand random walk representation. These techniques rely on the strict convexity of the interaction potential.

東京幾何セミナー

14:45-18:00   数理科学研究科棟(駒場) 056号室
場所は東大数理(駒場)、東京工業大学(大岡山)のいずれかで行います。
詳細については、上記セミナーURLよりご確認下さい。
「今後の予定」欄には、東工大で行われるセミナーは表��

近藤剛史 (Kondo Takefumi) 氏 (神戸大学大学院理学研究科) 14:45-16:15
Fixed point theorems for non-positively curved spaces and random groups
[ 講演概要 ]
It is not easy to construct a finitely generated group with a fixed point property for non-positively curved spaces. However, if we randomly choose relators, then we can get examples of such groups. To show this, we need a criterion for deducing a fixed point property from a local property of a group. In this talk, we will introduce one such criterion, and our approach is via a scaling limit argument.
赤穂まなぶ (Akaho Manabu) 氏 (首都大学東京大学院理工学研究科) 16:30-18:00
Lagrangian mean curvature flow and symplectic area
[ 講演概要 ]
In this talk, we consider symplectic area of smooth maps from a Riemann surface with boundary on embedded Lagrangian mean curvature flow in Kahler-Einstein manifolds. As an application, we observe a relation between embedded Lagrangian mean curvature flow and Floer theory of monotone Lagrangian submanifolds in Kahler-Einstein manifolds; in this case non-trivial holomorphic discs turn out to be an obstruction to the existence of long time solution of the flow.

GCOEセミナー

16:30-17:30   数理科学研究科棟(駒場) 370号室
O. Emanouilov 氏 (Colorado State University)
Partial Cauchy data for general second order elliptic operators in two dimensions
[ 講演概要 ]
We consider the problem of determining the coefficients of a first-order perturbation of the Laplacian in two dimensions by measuring the corresponding Cauchy data on an arbitrary open subset of the boundary. From this information we obtained a coupled PDE system of first order which the coefficients satisfy. As a corollary we show for the magnetic Schr"odinger equation that the magnetic field and the electric potential are uniquely determined by measuring the partial Cauchy data on an arbitrary part of the boundary. We also show that the coefficients of any real vector field perturbation of the Laplacian, the convection terms, are uniquely determined by their partial Cauchy data.

2009年10月13日(火)

トポロジー火曜セミナー

16:30-18:00   数理科学研究科棟(駒場) 056号室
Tea: 16:00 - 16:30 コモンルーム
笹平 裕史 氏 (東京大学大学院数理科学研究科)
Instanton Floer homology for lens spaces
[ 講演概要 ]
Let Y be an oriented closed 3-manifold and P be an SU(2)-bundle on Y. Under a certain condition, instanton Floer homology for Y can be defined as the Morse homology of the Chern-Simons functional. The condition is that all flat connections on P are irreducible. When there is a reducible flat connection on P, instanton Floer homology is not defined in general.
Since the fundamental group of a lens sapce is commutative, all flat connections on the lens space are reducible. In this talk I will introduce instanton Floer homology for lens spaces. I also show calculations for some lens spaces.

Lie群論・表現論セミナー

16:30-18:00   数理科学研究科棟(駒場) 126号室
小寺諒介 氏 (東京大学)
Extensions between finite-dimensional simple modules over a generalized current Lie algebra

[ 講演概要 ]
$\\mathfrak{g}$を$\\mathbb{C}$上の有限次元半単純Lie代数,$A$を有限生成可換$\\mathbb {C}$代数とする.
テンソル積$A \\otimes \\mathfrak{g}$に自然にLie代数の構造を与えたものを一般化されたカレントLie代数と呼ぶ.
一般化されたカレントLie代数の任意の2つの有限次元既約表現に対して,その1次のExt群を完全に決定することができたので,その結果について発表する.
[ 講演参考URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

2009年10月09日(金)

GCOE社会数理講演シリーズ

16:20-17:50   数理科学研究科棟(駒場) 117号室
岡本龍明 氏 (NTT 情報流通プラットフォーム研究所 岡本特別研究室長)
暗号の実践編

GCOEレクチャーズ

16:30-17:30   数理科学研究科棟(駒場) 128号室
Duflo氏による講義 2講目
Michel Duflo 氏 (Paris 7)
Associated varieties for Representations of classical Lie
super-algebras
[ 講演概要 ]
In this lecture, I'll discuss the notion of "Associated
varieties for Representations of classical Lie super-algebras (joint work with Vera Serganova)" and the relation with the degree of atypicality. This is related to a conjecture of Kac and Wakimoto.
[ 講演参考URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

2009年10月07日(水)

PDE実解析研究会

10:30-11:30   数理科学研究科棟(駒場) 056号室
北海道大学のHPには、第1回(2004年9月29日)~第38回(2008年10月15日)までの情報が掲載されております。
劉和平(Liu Heping) 氏 (Beijing University)
Wiener measure and Feynman-Kac formula on the Heisenberg group
[ 講演概要 ]
It is well known that the Feynman-Kac formula on the Euclidean space gives the solution of Schrodinger equation by the Wiener integral. We will discuss the Wiener measure and Feynman-Kac formula on the Heisenberg group. The results hold on the H-type groups.

GCOEレクチャーズ

16:30-17:30   数理科学研究科棟(駒場) 128号室
Duflo氏による一講目
Michel Duflo 氏 (Paris 7)
Representations of classical Lie super-algebras

[ 講演概要 ]
In this lecture, I'll survey classical topics on finite dimensional representations of classical Lie super-algebras, in particular the notion of the degree of atypicality.
[ 講演参考URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

代数学コロキウム

16:30-17:30   数理科学研究科棟(駒場) 056号室
Ahmed Abbes 氏 (Université de Rennes 1)
On GAGA theorems for the rigide-étale topology
[ 講演概要 ]
Last year, I finished my course in Todai on "Rigide Geometry following M. Raynaud" by stating a GAGA theorem for the rigide-étale topology, due to Gabber and Fujiwara. I will give a new proof of this theorem, inspired by another theorem of Gabber, namely the Affine analog of the proper base change theorem.

2009年10月05日(月)

GCOEレクチャーズ

15:30-17:00   数理科学研究科棟(駒場) 128号室
Claudio Landim 氏 (IMPA, Brazil)
Macroscopic fluctuation theory for nonequilibrium stationary states, Ⅲ

GCOEレクチャーズ

13:30-15:00   数理科学研究科棟(駒場) 128号室
Jean-Dominique Deuschel 氏 (TU Berlin)
Mini course on the gradient models, I: Effective gradient models, definitions and examples
[ 講演概要 ]
We describe a phase separation in $R^{d+1}$ by an effective interface model with basis in $Z^d$ and height in $R$. We assume that the interaction potential depends only on the discrete gradient and that the a priori measure is the product Lebesgue measure. Note that this is an unbounded massless model with continuous symmetry and this implies that the interface is delocalized for the infinite model in lower lattice dimensions $d=1,2$. Instead of looking at the distribution of the height of the interface itself, we consider the measure on the height differences the so called gradient Gibbs measure, which exists in any dimensions. The gradient field must satisfy the loop condition, that is the sum of the gradient along any closed loop is zero, this implies a long range interaction with a slow decay of the correlations. We are interested in characterizing the ergodic components of this gradient field, in the decay of correlations, large deviations and continuous scaling limits. As an example we consider the harmonic or discrete gaussian free field with quadratic interactions.

代数幾何学セミナー

16:40-18:10   数理科学研究科棟(駒場) 126号室
伊藤 敦 氏 (東大数理)
代数曲面上の随伴束の基底点集合について
[ 講演概要 ]
偏極付き代数多様体上(X,L)は、Lに数値的な条件を付け加えると
その随伴束が自由になったり、基底点集合が具体的にかけることがある。しかし
、曲線の場合は簡単であるが高次元の場合は難しい。今回の講演では主に代数曲
面の場合について解説する。

< 前へ 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138 次へ >