Seminar information archive

Seminar information archive ~02/21Today's seminar 02/22 | Future seminars 02/23~

2008/11/01

Monthly Seminar on Arithmetic of Automorphic Forms

13:30-16:00   Room #123 (Graduate School of Math. Sci. Bldg.)
宗野恵樹 (東京大学数理科学) 13:30-14:30
$(\\mathfrka{g},K)$-module structure of the principal series of $GL(3,\\mathfrak{C})$
[ Abstract ]
We give explicit description of the action of $\\mathfrak{gl}(3,\\mathbf{C}$ to the whole space of $K$-finite vectors of a given principal series representation of $GL(3,\\mathbf{C})$.
織田孝幸 (東京大学数理科学) 15:00-16:00
Toward effectively computable integral basis of simple $\\mathbfrak{gl}_4$-modules of finite dimension. (II)
[ Abstract ]
This is a continuation of the talk at Osaka in the occation of Kanrei workshop of Prof. T. Ibukiyama.
We discuss a part of the injection $V_{\\lambda} \\rightarrow \\mathfrak{p} \\otimes V_{\\lambda}$. Here $V_{\\lambda}$ is a simple module with highest weight $\\lambda$, and $\\mathfrak{p}$ is the adjoint representation with highest weight $(1,0,0,-1)$.

2008/10/31

Lecture Series on Mathematical Sciences in Soceity

16:20-17:50   Room #128 (Graduate School of Math. Sci. Bldg.)
岡本 龍明 (NTT研究所)
暗号の実践編

2008/10/30

Seminar on Probability and Statistics

16:20-17:30   Room #270 (Graduate School of Math. Sci. Bldg.)
若木 宏文 (広島大学大学院理学研究科)
正規母集団に関する検定統計量の分布の漸近展開の誤差評価
[ Abstract ]
多変量正規母集団に関する検定統計量の帰無分布の特性関数は、いくつかの多変量ガ ンマ関数の比として表されることが多い。Box (1949) はガンマ関数の漸近展開(ス ターリングの公式)を用いて、このような分布の大標本漸近展開公式を導出したが、 導出過程での剰余項を詳しく評価してゆくことで、分布関数の漸近展開近似の計算可 能な誤差限界を導出することができる。いくつかの検定統計量に対する大標本漸近展 開近似の誤差限界を導出し、高次元・大標本の枠組みで得られているエッジワース展 開近似の誤差限界と比較する。
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~kengok/statseminar/2008/08.html

Lectures

10:00-11:00   Room #002 (Graduate School of Math. Sci. Bldg.)
Arnaud DUCROT (University of Bordeaux)
Travelling wave solutions for an infection age structured epidemic model
[ Abstract ]
In this lecture, we study the existence of travelling wave solutions for a class of epidemic model structured in space and with respect ot the age of infection. We obtain necessary and sufficient conditions for the existence of travelling waves for such a class of problems. As a consequence, we also derive the existence of travelling waves for a class of functional partial differential equations.

2008/10/29

Seminar on Mathematics for various disciplines

10:30-11:30   Room #056 (Graduate School of Math. Sci. Bldg.)
木村芳文 (名古屋大学(多元数理科学研究科))
Stratified turbulence as an element of geophysical fluid dynamics
[ Abstract ]
Density stratification and rotation are the two major mechanisms that characterize the whole geophysical flows. In this talk, focusing on stable stratification, I will introduce some statistical, mechanical and geometrical aspects of stratified turbulence by showing the recent results of large scale computer simulations.

Number Theory Seminar

16:30-17:30   Room #056 (Graduate School of Math. Sci. Bldg.)
Daniel Caro (Université de Caen)
Overholonomicity of overconvergence $F$-isocrystals on smooth varieties
[ Abstract ]
Let $¥mathcal{V}$ be a complete discrete valuation ring
of characteristic $0$, with perfect residue field $k$ of
characteristic $p>0$. In order to construct $p$-adic coefficients
over $k$-varieties, Berthelot introduced the theory of
overconvergent $F$-isocrystals, i.e overconvergent isocrystals with
Frobenius structure. Moreover, to get a $p$-adic cohomology over
$k$-varieties stable under cohomological operations, Berthelot built
the theory of arithmetic $F$-$¥mathcal{D}$-modules. In this talk,
after recalling some elements of these theories, we introduce the
notion of overholonomicity with is a property as stable as the
holonomicity in the classical theory of $¥mathcal{D}$-modules. The
goal of the talk is to prove the overholonomicity of arithmetic
$¥mathcal{D}$-modules associated to overconvergent $F$-isocrystals
over smooth $k$-varieties. In the proof we need Christol's transfert
theorem, a comparison theorem between relative log rigid cohomology
and relative rigid cohomology and last but not least Kedlaya's
semistable reduction theorem. This is a joint work with Nobuo
Tsuzuki.

Seminar on Probability and Statistics

16:20-17:30   Room #128 (Graduate School of Math. Sci. Bldg.)
下平 英寿 (東京工業大学 情報理工学研究科)
マルチスケール・ブートストラップ法による確率値計算とFDR
[ Abstract ]
ブートストラップ確率はブートストラップ標本において仮説が支持される頻度であり, その実装の容易さから広く用いられている.たとえば,階層型クラスタリングにおいて得られたクラスタ が真実かどうかを判断する指標になる.ところが頻度論の不偏検定の立場で見ると,ブートストラップ確率 には無視できないくらい十分に大きいバイアスがあり,それはある種のパラメータ空間において仮説を あらわす領域の境界の曲率として解釈できることが知られている.本講演ではリサンプリングにおける データサイズを変化させたときの「スケール変換則」からバイアス補正する手法を紹介する. 曲面のテイラー展開のかわりにフーリエ変換をつかった漸近理論であり,錐のように必ずしもなめらかな曲面 でない場合でも適用できる (Shimodaira 2008).また,スケール変換則のアイデアをベイズ的なFalse Discovery Rateの計算に応用した最近の結果についても簡単に触れる.
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~kengok/statseminar/2008/07.html

2008/10/28

Tuesday Seminar on Topology

16:30-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
清野 和彦 (東京大学大学院数理科学研究科)
Nonsmoothable group actions on spin 4-manifolds
[ Abstract ]
We call a locally linear group action on a topological manifold nonsmoothable
if the action is not smooth with respect to any possible smooth structure.
We show in this lecture that every closed, simply connected, spin topological 4-manifold
not homeomorphic to neither S^2\\times S^2 nor S^4 allows a nonsmoothable
group action of any cyclic group with sufficiently large prime order
which depends on the manifold.

Lie Groups and Representation Theory

16:30-18:00   Room #126 (Graduate School of Math. Sci. Bldg.)
Joachim Hilgert (Paderborn University)
Chevalley's restriction theorem for supersymmetric Riemannian symmetric spaces
[ Abstract ]
We start by explaining the concept of a supersymmetric Riemannian symmetric spaces and present the examples studied by Zirnbauer in the context of universality classes of random matrices. For these classes we then show how to formulate and prove an analog of Chevalley's restriction theorem for invariant super-functions.

This is joint work with A. Alldridge (Paderborn) and M. Zirnbauer (Cologne)
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

Tuesday Seminar of Analysis

17:00-18:00   Room #123 (Graduate School of Math. Sci. Bldg.)
Serge Alinhac (パリ大学オルセイ校)
Introduction to geometric analysis of hyperbolic equations

2008/10/27

Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
松野 高典 (大阪府立高専)
複素射影平面上の有限Galois分岐被覆について

GCOE lecture series

16:30-17:30   Room #128 (Graduate School of Math. Sci. Bldg.)
Joachim Hilgert (Paderborn University)


Holomorphic extensions of highest weight representations to Olshanskii semigroups


[ Abstract ]
In this lecture I will present a proof of Olshanskii's Theorem, which says that
for a simple group of Hermitean type unitarizable highest weight
representations can be holomorphically extended to contractive representations
of a complex semigroup containing the group in its boundary.

2008/10/24

Colloquium

16:30-17:30   Room #002 (Graduate School of Math. Sci. Bldg.)
Benoit Collins (オタワ大学・東京大学大学院数理科学研究科)
On the spectral measure of the sum of elements in a finite von Neumann algebra
[ Abstract ]
Given two self-adjoint n×n matrices A and B with prescribed eigenvalues, the set of all possible spectral distributions for A+B has been conjectured by Horn and proved by Knutson, Tao, Klyachko and Totaro.
We address the same question when A and B have prescribed spectral measures but lie in an arbitrary II_1 factor, and we give elements of answers in terms of inequalities between the spectral measures. We explain the relation with the Connes embedding problem.

2008/10/23

Operator Algebra Seminars

16:30-18:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Emily Peters (UC Berkeley)
Planar algebras and the Haagerup subfactor

2008/10/22

Number Theory Seminar

16:30-17:30   Room #056 (Graduate School of Math. Sci. Bldg.)
Pierre Parent (Universite Bordeaux 1)
Serre's uniformity in the split Cartan case
[ Abstract ]
We show that, for large enough prime number p, the modular curve
X_{split}(p) has no other point with values in Q than CM points and the rational cusp. This gives a partial answer to an old question of J.-P. Serre concerning the uniform surjectivity of Galois representations associated to torsion points on elliptic curves without complex multiplication.
(Joint work with Yuri Bilu.)

2008/10/21

Lie Groups and Representation Theory

17:00-18:00   Room #126 (Graduate School of Math. Sci. Bldg.)
落合啓之 (名古屋大学)
Invitation to Atlas combinatorics
[ Abstract ]
半単純リー群のユニタリ表現の分類を手がける Atlas project(J. Adams, D. Vogan らが主催)では、実簡約(real reductive)線形代数群の admissible 表現をパラメトライズし、それに関するいくつかのプログラムが公開されています。ウェブサイトは www.liegroups.org.
現在、そのメインとなるものは Kazhdan-Lusztig-Vogan 多項式です。リー群として複素単純リー群を実リー群と見なしたケースが、通常の Kazhdan-Lusztig 理論に一致し、それを、ある一方向に拡張したのがここで扱われる KLV 理論と考えられます。

この講演では、リー群に関する背景説明などは軽く済ませ、Atlas で公開されているプログラムにおける方言、特に入出力の読み方を通常の言葉に言い換えることで、
プログラムを使ってもらう入り口での障壁を減らしたいと考えています。
ふむ、なかなか、使えるな、自分もインストールしてみようか、と思ってもらえれば、成功です。

なお、サーベイトークなので私のオリジナルな結果は含まれていません。また、計算機を使ってデモをする予定です。京都では計算機と板書の切り替えでばたばたしたので、照準を絞って慌てないように話したいと思います。
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

Tuesday Seminar on Topology

16:30-18:00   Room #002 (Graduate School of Math. Sci. Bldg.)
森山 哲裕 (東京大学大学院数理科学研究科)
On embeddings of 3-manifolds in 6-manifolds
[ Abstract ]
In this talk, we give a simple axiomatic definition of an invariant of
smooth embeddings of 3-manifolds in 6-manifolds.
The axiom is expressed in terms of some cobordisms of pairs of manifolds of
dimensions 6 and 3 (equipped with some cohomology class of the complement) and
the signature of 4-manifolds.
We then show that our invariant gives a unified framework for some classical
invariants in low-dimensions (Haefliger invariant, Milnor's triple
linking number, Rokhlin invariant, Casson invariant,
Takase's invariant, Skopenkov's invariants).

2008/10/20

Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
岩崎 克則 (九大数理)
パンルヴェ方程式と複素力学系

2008/10/17

Lecture Series on Mathematical Sciences in Soceity

16:20-17:50   Room #128 (Graduate School of Math. Sci. Bldg.)
岩根 和郎 (岩根研究所)
岩根研究所に於ける画像処理技術の紹介Ⅱ; CV技術による空間認識と対象物認識、及び人工知能

Lectures

15:00-16:00   Room #570 (Graduate School of Math. Sci. Bldg.)
Joachim Hilgert (Paderborn University)
GCOEレクチャー"Holomorphic extensions of unitary representations" その4 "Applications and open problems"
[ Abstract ]
In this lecture we present further applications of the given extension results and describe some open problems. In particular, we will mention estimates for automorphic forms (Krotz-Stanton), random matrices (Huckleberry-Puttmann-Zirnbauer), unitarizability of highest weight representation with non-scalar lowest K-type, and infinite dimensional groups.
[ Reference URL ]
http://faculty.ms.u-tokyo.ac.jp/users/gcoe/GCOE_lecture0810Hilgert.html

Algebraic Geometry Seminar

13:00-14:30   Room #128 (Graduate School of Math. Sci. Bldg.)
Yongnam Lee (Sogang U.)
Construction of surfaces of general type with pg=0 via
Q-Gorenstein smoothing

GCOE lecture series

15:00-16:00   Room #118 (Graduate School of Math. Sci. Bldg.)
Joachim Hilgert (Paderborn University)
Holomorphic extensions of unitary representations その4 Applications and open problems

[ Abstract ]
In this lecture we present further applications of the given extension results and describe some open problems. In particular, we will mention estimates for automorphic forms (Krötz-Stanton), random matrices (Huckleberry-Püttmann-Zirnbauer), unitarizability of highest weight representation with non-scalar lowest K-type, and infinite dimensional groups.
[ Reference URL ]
http://faculty.ms.u-tokyo.ac.jp/users/gcoe/GCOE_lecture0810Hilgert.html

2008/10/16

Operator Algebra Seminars

16:30-18:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Scott Morrison (UC Santa Barbara)
The $D_{2n}$ planar algebras

Lectures

15:00-16:00   Room #570 (Graduate School of Math. Sci. Bldg.)
Joachim Hilgert (Paderborn University)
GCOEレクチャー"Holomorphic extensions of unitary representations" その3 "Highest weight representations"
[ Abstract ]
In this lecture we explain the extension results in a little more detail and explain how they lead to geometric realizations of singular highest weight representations on nilpotent coadjoint orbits.
[ Reference URL ]
http://faculty.ms.u-tokyo.ac.jp/users/gcoe/GCOE_lecture0810Hilgert.html

Applied Analysis

16:00-17:30   Room #002 (Graduate School of Math. Sci. Bldg.)
Joseph F. Grotowski (University of Queensland)
Two-dimensional harmonic map heat flow versus four-dimensional Yang-Mills heat flow
[ Abstract ]
Harmonic map heat flow and Yang-Mills heat flow are the gradient flows associated to particular energy functionals. In the considered dimension, (i.e. dimension two for the harmonic map heat flow, dimension four for the Yang-Mills heat flow), the associated energy functional is (locally) conformally invariant, that is, the dimension is critical. This leads to a number of interesting phenomena when considering both the functionals and the associated flows. In this talk we discuss qualitative similarities and differences between the flows.

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