過去の記録

過去の記録 ~02/17本日 02/18 | 今後の予定 02/19~

代数幾何学セミナー

10:00-12:00   数理科学研究科棟(駒場) 128号室
10月16日開始, 毎週火曜10時から12時の連続講演です. 10月23日と12月4日は休講です.
Dmitry KALEDIN 氏 (Steklov研究所, 東大数理)
Homogical methods in Non-commutative Geometry
[ 講演概要 ]
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年10月15日(月)

Kavli IPMU Komaba Seminar

17:00-18:30   数理科学研究科棟(駒場) 002号室
Shinobu Hosono 氏 (The University of Tokyo)
Topics on string theory, mirror symmetry, and Gromov-Witten invariants
[ 講演概要 ]
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.

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
大沢健夫 氏 (名古屋大学)
On the curvature of holomorphic foliations

2007年10月13日(土)

保型形式の整数論月例セミナー

13:30-16:00   数理科学研究科棟(駒場) 123号室
若槻聡 氏 (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
[ 講演概要 ]
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 氏 (成蹊大学理工学部) 15:00-16:00
A propagation formula for principal series Whittaker functions on $GL(3,C)$
[ 講演概要 ]
$GL(n,\\mathbf{R})$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年10月11日(木)

作用素環セミナー

16:30-18:00   数理科学研究科棟(駒場) 056号室
Gandalf Lechner 氏 (Erwin Schroedinger Institute)
Construction of local nets from a wedge algebra

2007年10月10日(水)

代数幾何学セミナー

16:30-17:30   数理科学研究科棟(駒場) 117号室
代数学コロキウムとの合同講演会です. 15時から122号室でKaledinさんの講演があります.

James Lewis 氏 (University of Alberta)
Abel-Jacobi Maps Associated to Algebraic Cycles, I.

[ 講演概要 ]
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.

代数学コロキウム

16:30-17:30   数理科学研究科棟(駒場) 117号室
代数幾何学セミナーとの合同講演会です
James Lewis 氏 (University of Alberta)
Abel-Jacobi Maps Associated to Algebraic Cycles I

[ 講演概要 ]
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.

東京幾何セミナー

14:40-18:00   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��

山川 大亮 氏 (京都大学大学院 理学研究科) 14:40-16:10
A multiplicative analogue of quiver variety
[ 講演概要 ]
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 氏 (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
[ 講演概要 ]
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.

統計数学セミナー

16:20-17:30   数理科学研究科棟(駒場) 122号室
清 智也 氏 (東大情報理工)
勾配モデルの摂動解析と許容領域の評価
[ 講演概要 ]
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.
[ 講演参考URL ]
http://www.ms.u-tokyo.ac.jp/~kengok/statseminar/2007/06.html

代数幾何学セミナー

15:00-16:00   数理科学研究科棟(駒場) 122号室
Dmitry Kaledin 氏 (Steklov Institute)
p-adic Hodge theory in the non-commutative setting
[ 講演概要 ]
We will explain what is the natural replacement of the notion of Hodge structure in the p-adic setting, and how to construct such a structure for non-commutative manifolds (something which at present cannot be done for the usual Hodge structures, but works perfectly well for the p-adic analog).

2007年10月09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
浅岡 正幸 氏 (京都大学大学院理学研究科)
Classification of codimension-one locally free actions of the affine group of the real line.
[ 講演概要 ]
By GA, we denote the group of affine and orientation-preserving transformations
of the real line. In this talk, I will report on classification of locally free action of
GA on closed three manifolds, which I obtained recently. In 1979, E.Ghys proved
that if such an action preserves a volume, then it is smoothly conjugate to a homogeneous action. However, it was unknown whether non-homogeneous action exists. As a consequence of the classification, we will see that the unit tangent bundle of a closed surface of higher genus admits a finite-parameter family of
non-homogeneous actions.

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
Michael Pevzner 氏 (Reims University and University of Tokyo)
Rankin-Cohen brackets and covariant quantization
[ 講演概要 ]
The particular geometric structure of causal symmetric spaces permits the definition of a covariant quantization of these homogeneous manifolds.
Composition formulae (#-products) of quantizad operators give rise to a new interpretation of Rankin-Cohen brackets and allow to connect them with the branching laws of tensor products of holomorphic discrete series representations.
[ 講演参考URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

2007年10月04日(木)

作用素環セミナー

16:30-18:00   数理科学研究科棟(駒場) 056号室
Gandalf Lechner 氏 (Erwin Schroedinger Institute)
Local nets of von Neumann algebras and modular theory

2007年10月02日(火)

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
Pablo Ramacher 氏 (Gottingen University)


Invariant integral operators on affine G-varieties and their kernels
[ 講演概要 ]
We consider certain invariant integral operators on a smooth affine variety M carrying the action of a reductive algebraic group G, and assume that G acts on M with an open orbit. Then M is isomorphic to a homogeneous vector bundle, and can locally be described via the theory of prehomogenous vector spaces. We then study the Schwartz kernels of the considered operators, and give a description of their singularities using the calculus of b-pseudodifferential operators developed by Melrose. In particular, the restrictions of the kernels to the diagonal can be described in terms of local zeta functions.
[ 講演参考URL ]
http://www.ms.u-tokyo.ac.jp/~toshi/seminar/ut-seminar.html

2007年09月28日(金)

談話会・数理科学講演会

16:30-17:30   数理科学研究科棟(駒場) 123号室
お茶&Coffee&お菓子: 16:00~16:30(コモンルーム)
Marko Tadic' 氏 (University of Zagreb)
Irreducible unitary representations and automorphic forms

[ 講演概要 ]
Unitary representations of adelic groups in the spaces of automorphic forms are big source of important irreducible unitary representations of classical groups over local fields.

We shall present classifications of some classes of irreducible unitary representations (older, as well as quite new), describe
isolated unitary representations among them, and discuss which of them can be obtained from spaces of automorphic forms.

2007年09月26日(水)

代数幾何学セミナー

16:30-18:00   数理科学研究科棟(駒場) 126号室
Grigory Mikhalkin 氏 (Toronto大学)
Floor diagrams and enumeration of tropical curves
[ 講演概要 ]
The enumerative problems considered in this talk are finding the number of curves in projective spaces (over complex, real and tropical numbers) of given genus and degree constrained by certain incidence conditions (e.g. passing via points or lines). Floor diagrams are a combinatorial tool that reduces an enumerative problem in dimension n to the corresponding problem n dimension n-1. Floor diagrams give a constructive (and rather efficient) way to find all tropical curves for a given enumerative problem. And once we have a tropical solution of the problem we can use it to solve the corresponding problems over the complex and real numbers.

2007年09月19日(水)

代数学コロキウム

16:30-17:30   数理科学研究科棟(駒場) 117号室
Gereon Quick 氏 (Universitaet Muenster)
Etale cobordism
[ 講演概要 ]
We define and study a new candidate of etale topological cohomology theories for schemes over a field of abritrary characteristic: etale cobordism. As etale K-theory is related to algebraic K-theory, etale cobordism is related to algebraic cobordism of Voevodsky and Levine/Morel. It shares some nice properties of topological theories, e.g. it is equipped with an Atiyah-Hirzebruch spectral sequence from etale cohomology. We discuss in particular a comparison theorem between etale and algebraic cobordism after inverting a Bott element and, finally, we give an outlook to further possible applications of this theory.

2007年09月15日(土)

保型形式の整数論月例セミナー

13:30-16:00   数理科学研究科棟(駒場) 117号室
長谷川泰子 氏 (東京大学数理科学) 13:30-14:30
Siegl principal series Whittaker functions on $Sp(2,\\mathbf{R})$
(部屋は056室)
[ 講演概要 ]
2次シンプレクティック群のSiegel極大放物型部分群から誘導された一般型主系列表現に対するWhittaker関数の級数表示と積分表示を与えることを目的とし,Whittaker関数の満たす微分評定式を与え,その解の構成に向けて現在進めている研究の方針を述べる.
(部屋は,冷房効く056室に変更です)
市川尚志 氏 (佐賀大学理工学部) 15:00-16:00
A higher rank version of Abel-Jacobi's theorem (Room 056)
[ 講演概要 ]
極大退化曲線に近いリーマン面上のベクトル束とそのモジュライについて話す.次数0の安定ベクトル束が,リーマン面を一意化するショットキー群の線形表現から得られることを述べ,ショットキー群の線形表現の空間とベクトル束のモジュライ空間の関係を,アーベル・ヤコビの定理,フェアリンデ公式を用いて考察する.
(部屋は117号室です)

2007年09月12日(水)

代数幾何学セミナー

15:00-18:00   数理科学研究科棟(駒場) 117号室
代数学コロキウムとの合同講演会です.
E. Lau 氏 (Univ. of Bielefeld) 15:00-15:45
Classification of p-divisible groups by displays and duality
T. Zink 氏 (Univ. of Bielefeld) 16:00-16:45
Applications of the theory of displays
E. Looijenga 氏 (Univ. of Utrecht) 17:00-18:00
Presentation of mapping class groups from algebraic geometry
[ 講演概要 ]
A presentation of the mapping class group of a genus g surface with one hole is due to Wajnryb with later improvements due to M. Matsumoto. The generators are Dehn twists defined by 2g+1 closed curves on the surface. The relations involving only two Dehn twists are the familiar Artin relations, we show that those involving more than two can be derived from algebro-geometry considerations.

代数学コロキウム

15:00-18:00   数理科学研究科棟(駒場) 117号室
代数幾何学セミナーとの合同講演会です
E. Lau 氏 (Univ. of Bielefeld) 15:00-15:45
Classification of p-divisible groups by displays and duality
T. Zink 氏 (Univ. of Bielefeld) 16:00-16:45
Applications of the theory of displays
E. Looijenga 氏 (Univ. of Utrecht) 17:00-18:00
Presentation of mapping class groups from algebraic geometry
[ 講演概要 ]
A presentation of the mapping class group of a genus g surface with one hole is due to Wajnryb with later improvements due to M. Matsumoto. The generators are Dehn twists defined by 2g+1 closed curves on the surface. The relations involving only two Dehn twists are the familiar Artin relations, we show that those involving more than two can be derived from algebro-geometry considerations.

2007年09月05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
Reinhard Farwig 氏 (Darmstadt University of Technology)
Reguarity of Weak Solutions to the Navier-Stokes System beyond Serrin's Criterion
[ 講演概要 ]
Consider a weak instationary solution $u(x,t)$ of the Navier-Stokes equations in a domain $\\Omega \\subset \\mathbb{R}^3$ in the sense of Leray-Hopf. As is well-known, $u$ is is unique and regular if $u\\in L^s(0,T;L^q(\\Omega))$ satisfies the {\\it strong energy inequality} and $s,q$ satisfy Serrin's condition $\\frac{2}{s} + \\frac{3}{q}=1$, $s>2,\\, q>3$. Now consider $u$ such that $$u\\in L^r(0,T;L^q(\\Omega))\\quad \\mbox{ where }\\quad \\frac{2}{r} + \\frac{3}{q}>1$$ and has a sufficiently small norm in $L^r(0,T;L^q(\\Omega))$. Then we will prove that $u$ is regular. Similar results of local rather than global type in space will be proved provided that $u$ satisfies the {\\it localized energy inequality}. Finally H\\"older continuity of the kinetic energy in time will imply regularity.

The proofs use local in time regularity results which are based on the {\\it theory of very weak solutions} and on uniqueness arguments for weak solutions.
[ 講演参考URL ]
http://coe.math.sci.hokudai.ac.jp/sympo/pde_ra/index.html

2007年08月29日(水)

代数幾何学セミナー

17:00-18:00   数理科学研究科棟(駒場) 128号室
Valery Alexeev 氏 (Georgia大学)
Computations on the moduli spaces of weighted log pairs

2007年08月27日(月)

代数学コロキウム

16:30-17:30   数理科学研究科棟(駒場) 002号室
Steven Zucker 氏 (Johns Hopkins大学)
The reductive Borel-Serre motive

2007年08月02日(木)

代数幾何学セミナー

16:30-18:00   数理科学研究科棟(駒場) 126号室
De-Qi Zhang 氏 (Singapore大学)
Dynamics of automorphisms on algebraic varieties
[ 講演概要 ]
The building blocks of automorphisms / endomorphisms of compact varieties are determined --- an algebro geometric approach towards dynamics.

2007年07月25日(水)

統計数学セミナー

16:20-17:30   数理科学研究科棟(駒場) 122号室
小林 景 氏 (統計数理研究所, 学振特別研究員)
大規模ランダム行列のスペクトル理論とデータ解析への応用(Review)
[ 講演概要 ]
The empirical spectral distribution of random matrices have been studied since Wigner's pioneering work on the semicircular law in the 1950's. The result says that the empirical spectral distribution of a symmetric matrix with i.i.d. random elements converges to the semicircular law as the size of the matrix becomes large. Though this result is beautiful in theory, its application has been limited to a few problems in nuclear physics and coding theory. The next breakthrough was the Marcenko-Pastur (M-P) law for the asymptotic spectral distribution of sample covariance matrices. The M-P law has found more applications, in particular high dimensional statistical data analysis, than the semicircular law.

In this talk I will first review these two significant results. Each of them has three completely different proofs. Then I will explain several other theoretical results that have mostly been studied this decade. Finally, I will present some of the applications of these results. This review is partly based on lectures on random matrices given by P. Bickel, N. El-Karoui and A. Guionnet, and also some seminars at UC Berkeley.

(# This talk is almost the same as the talk I gave at ISM on June 1.)
[ 講演参考URL ]
http://www.ms.u-tokyo.ac.jp/~kengok/statseminar/2007/05.html

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