Seminar information archive

Seminar information archive ~05/21Today's seminar 05/22 | Future seminars 05/23~

2007/10/31

Seminar on Probability and Statistics

16:20-17:30   Room #122 (Graduate School of Math. Sci. Bldg.)
深澤 正彰 (東京大学大学院数理科学研究科)
最尤推定量の漸近展開とその応用:とくに拡散過程の場合について
[ Abstract ]
最尤推定量とそのスチューデント化統計量の漸近展開公式について、 スキューネス修正の観点から考察し、AR過程や、あるクラスの拡散過程モデルへの応用について述べる。 一般の対称拡散過程モデルにおける最尤推定量のバイアス推定量、 スキューネス推定量も提案する。
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~kengok/statseminar/2007/07.html

Number Theory Seminar

16:30-17:30   Room #117 (Graduate School of Math. Sci. Bldg.)
Pierre Colmez (Ecole Polytechnique)
On the p-adic local Langlands correspondance for GL2(Qp)

2007/10/30

Lie Groups and Representation Theory

16:30-18:00   Room #126 (Graduate School of Math. Sci. Bldg.)
松本久義 (東京大学大学院数理科学研究科)
On Weyl groups for parabolic subalgebras
[ Abstract ]
Let ${\\mathfrak g}$ be a complex semisimple Lie algebra.
We call a parabolic subalgebra ${\\mathfrak p}$ of ${\\mathfrak g}$
normal, if any parabolic subalgebra which has a common Levi part with ${\\mathfrak p}$
is conjugate to ${\\mathfrak p}$ under an inner automorphism of ${\\mathfrak g}$.
For a normal parabolic subalgebra, we have a good notion of the restricted root system
or the little Weyl group. We have a comparison result on the Bruhat order on the Weyl group for
${\\mathfrak g}$ and the little Weyl group.
We also apply this result to the existence problem of the homomorphisms between scalar generalized Verma modules.
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

Lie Groups and Representation Theory

15:00-16:30   Room #126 (Graduate School of Math. Sci. Bldg.)
Michaël Pevzner (Université de Reims and University of Tokyo)
Quantization of symmetric spaces and representation. II
[ Abstract ]
Back to Mathematics. Two methods of quantization.

We will start with a discussion on

-Weyl symbolic calculus on a symplectic vector space
and its asymptotic behavior.


In the second part, as a consequence of previous considerations, we will define the notion of deformation quantization.
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

Algebraic Geometry Seminar

10:00-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Dmitry KALEDIN (Steklov研究所, 東大数理)
Homological methods in Non-commutative Geometry

Tuesday Seminar on Topology

17:00-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
太田 啓史 (名大多元数理)
$L_{\\infty}$ action on Lagrangian filtered $A_{\\infty}$ algebras.
[ Abstract ]
I will discuss $L_{\\infty}$ actions on Lagrangian filtered
$A_{\\infty}$ algebras by cycles of the ambient symplectic
manifold. In the course of the construction,
I like to remark that the stable map compactification is not
sufficient in some case when we consider ones from genus zero
bordered Riemann surface. Also, if I have time, I like to discuss
some relation to (absolute) Gromov-Witten invariant and other
applications.
(This talk is based on my joint work with K.Fukaya, Y-G Oh and K. Ono.)

2007/10/29

Kavli IPMU Komaba Seminar

17:00-18:30   Room #002 (Graduate School of Math. Sci. Bldg.)
Hiroshige Kajiura (RIMS, Kyoto University)
Some examples of triangulated and/or $A_\\infty$-categories
related to homological mirror symmetry

[ Abstract ]
In this talk, I would like to discuss on some examples of
triangulated and/or $A_\\infty$-categories associated to
manifolds with additional structures
(symplectic structure, complex structure, ...)
which can appear in the homological mirror symmetry (HMS) set-up
proposed by Kontsevich'94.

The strongest form of the HMS may be to show the equivalence
of Fukaya category on a symplectic manifold with the category
of coherent sheaves on the mirror dual complex manifold
at the level of $A_\\infty$-categories.
On the other hand, for a given $A_\\infty$-category,
there is a canonical way (due to Bondal-Kapranov, Kontsevich)
to construct an enlarged $A_\\infty$-category
whose restriction to the zero-th cohomology forms a triangulated category.

I plan to talk about the triangulated structure of categories
associated to regular systems of weights
(joint work with Kyoji Saito and Atsushi Takahashi),
and also give a realization of higher $A_\\infty$-products in
Fukaya categories from the mirror dual complex manifold
via HMS in some easy examples.

2007/10/25

Operator Algebra Seminars

16:30-18:00   Room #410 (Graduate School of Math. Sci. Bldg.)
見村万佐人 (東大数理)
An introduction to expander graphs

Lie Groups and Representation Theory

16:30-18:00   Room #002 (Graduate School of Math. Sci. Bldg.)
Michael Pevzner (Universite de Reims and University of Tokyo)
Quantization of symmetric spaces and representations. I
[ Abstract ]
The first and introductory lecture of a series of four will be devoted to the discussion of fundamental principles of the Quantum mechanics and their mathematical formulation. This part is not essential for the rest of the course but it might give a global vision of the subject to be considered.

We shall introduce the Weyl symbolic calculus, that relates classical and quantum observables, and will explain its relationship with the so-called deformation quantization of symplectic manifolds.

Afterwards, we will pay attention to a more algebraic question of formal deformation of an arbitrary smooth Poisson manifold and will define the Kontsevich star-product.
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

2007/10/24

Number Theory Seminar

16:30-17:30   Room #117 (Graduate School of Math. Sci. Bldg.)
阿部知行 (東京大学大学院数理科学研究科)
l進層のSwan導手とunit-root
overconvergent F-isocrystalの特性サイクルについて
[ Abstract ]
今回の講演ではBerthelotによる数論的D加群の理論を用いることによってunit-root overconvergent F-isocrystalに対してSwan導手を定義し、Kato-Saitoにより幾何学的な手法を用いて定義されたSwan導手と比較する。応用として、特異点の解消の仮定のもとでKato-SaitoのSwan導手の整数性予想を導く。

2007/10/23

Tuesday Seminar on Topology

16:30-18:00   Room #002 (Graduate School of Math. Sci. Bldg.)
Jun O'Hara (首都大学東京)
Spaces of subspheres and their applications
[ Abstract ]
The set of q-dimensional subspheres in S^n is a Grassmann manifold which has natural pseudo-Riemannian structure, and in some cases, symplectic structure as well. Both of them are conformally invariant.
I will explain some examples of their applications to geometric aspects of knots and links.

Tuesday Seminar of Analysis

17:00-18:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Fr\'{e}d\'{e}ric Klopp (パリ北大学)
Localization for random quantum graphs (joint with K. Pankrashkin)

2007/10/22

Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
志賀弘典 (千葉大学)
ガウス算術幾何平均定理の多変数化とその保型形式的解釈(小池健二氏との共同研究)

2007/10/18

Operator Algebra Seminars

16:30-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
Mikael Pichot (学振・東大数理)
On the classification of Bruhat-Tits buildings

2007/10/17

Lectures

16:00-17:00   Room #470 (Graduate School of Math. Sci. Bldg.)
J. Fritz (TU Budapest)
The method of compensated compactness for
microscopic systems

2007/10/16

Tuesday Seminar on Topology

17:00-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
二木 昭人 (東京工業大学大学院理工学研究科)
Toric Sasaki-Einstein manifolds
[ Abstract ]
A compact toric Sasaki manifold admits a Sasaki-Einstein metric if and only if it is obtained by the Delzant construction from a toric diagram of a constant height. As an application we see that the canonical line bundle of a toric Fano manifold admits a complete Ricci-flat K\\"ahler metric.

Algebraic Geometry Seminar

10:00-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Dmitry KALEDIN (Steklov研究所, 東大数理)
Homogical methods in Non-commutative Geometry
[ Abstract ]
Of all the approaches to non-commutative geometry, probably the most promising is the homological one, developed by Keller, Kontsevich, Toen and others, where non-commutative eometry is understood as "geometry of triangulated categories". Examples of "geometric" triangulated categories come from representation theory, symplectic geometry (Fukaya category) and algebraic geometry (the derived category of coherent sheaves on an algebraic variety and
various generalizations). Non-commutative point of view is expected to be helpful even in traditional questions of algebraic geometry such as the termination of flips.

We plan to give an introduction to the subject, with emphasis on homological methods (such as e.g. Hodge theory which, as it turns out, can be mostly formulated in the non-commutative setting).

No knowledge of non-commutative geometry whatsoever is assumed. However, familiarity with basic homological algebra and algebraic geometry will be helpful.

2007/10/15

Kavli IPMU Komaba Seminar

17:00-18:30   Room #002 (Graduate School of Math. Sci. Bldg.)
Shinobu Hosono (The University of Tokyo)
Topics on string theory, mirror symmetry, and Gromov-Witten invariants
[ Abstract ]
Recently, some technical developments in solving BCOV
(Bershadsky-Cecotti-Ooguri-Vafa) holomorphic anomaly equation has been
made and it has become possible to predict higher genus Gromov-Witten
invariants for some class of Calabi-Yau 3 folds.

With a brief introduction to BCOV equation, I will present some
predictions for Gromov-Witten invariants of certain Calabi-Yau 3 folds,
which are not birational but derived equivalent. (This is based on
a work with Y. Konishi which appeared in mathAG/0704.2928.)

Before coming to this specific topic, I will review some recent
topics of the homological mirror symmetry focusing on
its connection to the `classical' mirror symmetry, where the
variation theory of Hodge structures (VHS) plays a central role.
The BCOV equation and its open string generalization have their grounds
on the VHS.

Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
大沢健夫 (名古屋大学)
On the curvature of holomorphic foliations

2007/10/13

Monthly Seminar on Arithmetic of Automorphic Forms

13:30-16:00   Room #123 (Graduate School of Math. Sci. Bldg.)
若槻聡 (金沢大学理学部) 13:30-14:30
2次のジーゲルカスプ形式の空間上のヘッケ作用素の明示的跡公式について
2次のジーゲルカスプ形式の空間上のヘッケ作用素の明示的跡公式について
[ Abstract ]
2次のジーゲルカスプ形式の空間上のヘッケ作用素の跡に、ある明示的公式を与
える。まだ公式から跡の具体的な数値を得ることはできないが、この公式は数値を得る
ための一つのステップとなっている。一変数の場合や一般論と比較しながら、得られた公式と今後の目標について解説する。
平野幹 (成蹊大学理工学部) 15:00-16:00
A propagation formula for principal series Whittaker functions on $GL(3,C)$
[ Abstract ]
$GL(n,\\mathbf{R})$上のクラス1Whittaker関数を$GL(n-1,\\mathbf{R})$上の同関数で表す公式が石井-Stadeにより得られてる(J. Funct. Anal. 244 (2007))。また、$GL(n,\\mathbf{R})$および$GL(n,\\mathbf{C})$上のクラス1Whittaker関数のelementaryな関係(Stade (1995)) により、この公式は$GL(n,\\mathbf{C})$上のクラス1Whittaker関数に対しても成立する。ここでは$GL(3,\\mathbf{C})$上のクラス1でない主系列Whittaker関数の明示公式(織田孝幸氏との共同研究)に基づき、これを$GL(2,\\mathbf{C})$上のクラス1でない主系列Whittaker関数で表す類似の公式を紹介する。

2007/10/11

Operator Algebra Seminars

16:30-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
Gandalf Lechner (Erwin Schroedinger Institute)
Construction of local nets from a wedge algebra

2007/10/10

Algebraic Geometry Seminar

16:30-17:30   Room #117 (Graduate School of Math. Sci. Bldg.)
James Lewis (University of Alberta)
Abel-Jacobi Maps Associated to Algebraic Cycles, I.

[ Abstract ]
This talk concerns the Bloch cycle class map from the higher Chow groups to Deligne cohomology of a projective algebraic manifold. We provide an explicit formula for this map in terms of polylogarithmic type currents.

Number Theory Seminar

16:30-17:30   Room #117 (Graduate School of Math. Sci. Bldg.)
James Lewis (University of Alberta)
Abel-Jacobi Maps Associated to Algebraic Cycles I

[ Abstract ]
This talk concerns the Bloch cycle class map from the higher Chow groups to Deligne cohomology of a projective algebraic manifold. We provide an explicit formula for this map in terms of polylogarithmic type currents.

Geometry Seminar

14:40-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
山川 大亮 (京都大学大学院 理学研究科) 14:40-16:10
A multiplicative analogue of quiver variety
[ Abstract ]
本講演では,箙(quiver)に付随して現れる新しい複素シンプレクティック多様体を紹介する.これは中島によって導入された箙多様体と非常に良く似た構成をする事で得られるが,違いは運動量写像ではなく群値運動量写像と呼ばれるものを使って商を取るところにある.この多様体は箙多様体と良く似た幾何学的性質を有し,一方,星型箙の場合に点付きRiemann球面上の放物接続のモジュライ空間とRiemann-Hilbert対応によって関係している.また箙多様体との直接的な関係も存在している.これらについて説明したい.
加藤 晃史 (東京大学大学院数理科学研究科) 16:30-18:00
AdS/CFT 対応における変分問題について
[ Abstract ]
弦双対性の一つである AdS/CFT 対応は,重力場(時空の幾何学)とゲージ理論(共形場理論)との間に対応があるという予想である.講演ではこの予想について概観するとともに,その一例として,佐々木・アインシュタイン多様体の体積に関する変分問題と quiver ゲージ理論の a-maximization の関係を説明したい.

Seminar on Probability and Statistics

16:20-17:30   Room #122 (Graduate School of Math. Sci. Bldg.)
清 智也 (東大情報理工)
勾配モデルの摂動解析と許容領域の評価
[ Abstract ]
多変量標準正規分布を凸関数の勾配写像によって 引き戻すと, 一つの確率分布が得られる. さらにパラメトリックな勾配写像を考えれば, 統計モデルが得られる. この統計モデルを勾配モデルと呼ぶことにする. 本講演は二つの内容からなる. 第一に, 恒等写像に摂動を加えた勾配写像を考え, 対応する密度関数, キュムラント母関数, ダイバージェンスなどの摂動展開を求める. 第二に, より具体的な勾配モデルに対して, パラメータが定義域に属すための十分条件を示す. このような考察の必要性は, 定義域が無限個の 制約式で与えられることによる.
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~kengok/statseminar/2007/06.html

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