## 過去の記録

### 2009年05月22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) 002号室
お茶&Coffee&お菓子: 16:00～16:30 (コモンルーム)

[ 講演概要 ]

#### 代数幾何学セミナー

15:00-16:30   数理科学研究科棟(駒場) 128号室
Prof. Steven Zucker 氏 (Johns Hopkins University)
The RBS compactification: a real stratified space in
algebraic geometry

### 2009年05月20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

Stability of the Burgers vortex
[ 講演概要 ]
The Burgers vortex is an exact vortex solution to the three dimensional stationary Navier-Stokes equations for viscous incompressible fluids in the presence of an axisymmetric background straining flow. In this talk we discuss the stability of the Burgers vortex with respect to two or three dimensional perturbation flows.

#### 数理ファイナンスセミナー

17:30-19:00   数理科学研究科棟(駒場) 122号室

Financial inverse problem and reconstruction of infinitely divisible distributions with Gaussian component (小谷真一氏(関西学院大)との共同研究)

#### 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

Generalized Whittaker functions for degenerate principal series of GL(4,R)

### 2009年05月19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
Mark Hamilton 氏 (東京大学大学院数理科学研究科, JSPS)
Geometric quantization of integrable systems
[ 講演概要 ]
The theory of geometric quantization is one way of producing a "quantum system" from a "classical system," and has been studied a great deal over the past several decades. It also has surprising ties to representation theory. However, despite this, there still does not exist a satisfactory theory of quantization for systems with singularities.

Geometric quantization requires the choice of a polarization; when using a real polarization to quantize a regular enough manifold, a result of Sniatycki says that the quantization can be found by counting certain objects, called Bohr-Sommerfeld fibres. However, there are many types of systems to which this result does not apply. One such type is the class of completely integrable systems, which are examples coming from mechanics that have many nice properties, but which are nontheless too singular for Sniatycki's theorem to apply.

In this talk we will explore one approach to the quantization of integrable systems, and show a Sniatycki-type relationship to Bohr-Sommerfeld fibres. However, some surprising features appear, including infinite-dimensional contributions and strong dependence on the polarization.

This is joint work with Eva Miranda.

### 2009年05月18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) 126号室

Conformal symmetries of self-dual hyperbolic monopole metrics (joint work with Jeff Viaclovsky)

### 2009年05月16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

3次元上半空間のスペクトル理論とエルミート保型形式
[ 講演概要 ]
3次元上半空間のスペクトル理論のエルミート保型形式への応用につい
て述べます。内容はジーゲル保型形式に対して2次元上半空間のスペクトル理論を応用す
るという今井氏による発見、及びその実際的応用のエルミート版への類似です。具体的に
は小嶋氏により発見されたエルミート版斉藤・黒川リフトに逆定理による解析的証明を与
えること、レベル付エルミート・アイゼンシュタイン級数のフーリエ係数の決定、それを

による記述、についてです。これらにおいて必要となる「3次元上半空間のマース形式の

ク・サルナック型の結果についても述べます。(p進エルミート・アイゼンシュタイン級

The Eisenstein series for $GL(3,Z)$ induced from cusp forms
[ 講演概要 ]

### 2009年04月30日(木)

#### 応用解析セミナー

16:00-17:30   数理科学研究科棟(駒場) 002号室

ギーラー・マインハルト方程式に対するシャドウ系おける多重スポットの不安定性
[ 講演概要 ]

この系にはスポットパターンと呼ばれる定常解が存在することが知られており、この解は、その値が非常に大きい点(スポット)を持つこととその近傍の外側では急激に値が減少することにより特徴付けされる。

#### 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

Measure Equivalence Rigidity and Bi-exactness of Groups

### 2009年04月28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

The ambient metric in conformal geometry
[ 講演概要 ]
In 1985, Charles Fefferman and Robin Graham gave a method for realizing a conformal manifold of dimension n as a submanifold of a Ricci-flat Lorentz metric on a manifold of dimension n+2, which is now called the ambient space. Using this correspondence, one can construct many examples of conformal invariants and conformally invariant operators. However, if n is even, their construction of the ambient space is obstructed at the jet of order n/2 and thereby the application of the ambient space was limited. In this talk, I'll recall basic ideas of the ambient space and then explain how to avoid the difficulty and go beyond the obstruction. This is a joint work with Robin Graham.

#### 解析学火曜セミナー

16:30-18:00   数理科学研究科棟(駒場) 128号室

### 2009年04月27日(月)

#### 代数幾何学セミナー

15:30-18:00   数理科学研究科棟(駒場) 122号室
Prof. Alessandra Sarti 氏 (Universite de Poitier) 15:30-16:30
Automorphism groups of K3 surfaces
[ 講演概要 ]
I will present recent progress in the study of prime order automorphisms of K3 surfaces.
An automorphism is called (non-) symplectic if the induced
operation on the global nowhere vanishing holomorphic two form
is (non-) trivial. After a short survey on the topic, I will
describe the topological structure of the fixed locus, the
geometry of these K3 surfaces and their moduli spaces.

Prof. Samuel Boissier 氏 (Universite de Nice
) 17:00-18:00
The cohomological crepant resolution conjecture

[ 講演概要 ]
The cohomological crepant resolution conjecture is one
form of Ruan's conjecture concerning the relation between the
geometry of a quotient singularity X/G - where X is a smooth
complex variety and G a finite group of automorphisms - and the
geometry of a crepant resolution of singularities of X/G ; it
generalizes the classical McKay correspondence. Following the
examples of the Hilbert schemes of points on surfaces and the
weighted projective spaces, I will present some of the recents
developments of the subject.

### 2009年04月23日(木)

#### 作用素環セミナー

16:30-18:00   数理科学研究科棟(駒場) 128号室

Entire Cyclic Cohomology of Noncommutative 2-Tori

### 2009年04月22日(水)

#### PDE実解析研究会

10:30-11:30   数理科学研究科棟(駒場) 128号室
いつもとは会場が異なります。
Wilhelm Klingenberg 氏 (University of Durham)
From Codazzi-Mainardi to Cauchy-Riemann
[ 講演概要 ]
In joint work with Brendan Guilfoyle we established an upper bound for the winding number of the principal curvature foliation at any isolated umbilic of a surface in Euclidean three-space. In our talk, we will focus on the analytic core of the problem. Here is a model of the triaxial ellipsoid with its curvature foliation and one umbilic on the right.

#### 東京幾何セミナー

14:45-18:00   数理科学研究科棟(駒場) 122号室

「今後の予定」欄には、東工大で行われるセミナーは表��

Einstein-Weyl structures on 3-dimensional Severi varieties
[ 講演概要 ]
The space of nodal curves on a projective surface is called a Severi variety.In this talk, we show that any Severi variety of nodal rational curves on a non-singular projective surface is always equipped with a natural Einstein-Weyl structure, if the space is 3-dimensional. This is a generalization of the Einstein-Weyl structure on the space of smooth rational curves on a complex surface, given by N. Hitchin in the context of twistor theory. We will explain some properties of the Einstein-Weyl spaces given by this method, and we will also show some examples of such Einstein-Weyl spaces. (This is a joint work with Nobuhiro Honda.)
Tamas Hausel 氏 (Oxford University) 16:30-18:00
Toric non-Abelian Hodge theory
[ 講演概要 ]
First we give an overview of the geometrical and topological aspects of the spaces in the non-Abelian Hodge theory of a curve and their connection with quiver varieties. Then by concentrating on toric hyperkaehler varieties in place of quiver varieties we construct the toric Betti, De Rham and Dolbeault spaces and prove several of the expected properties of the geometry and topology of these varieties. This is joint work with Nick Proudfoot.

#### 統計数学セミナー

15:00-16:10   数理科学研究科棟(駒場) 128号室
Arnaud DOUCET 氏 (統計数理研究所)
Interacting Markov chain Monte Carlo Methods for Solving Nonlinear Measure-Valued Equations
[ 講演概要 ]
We present a new class of interacting Markov chain Monte Carlo algorithms for solving numerically discrete-time measure-valued equations. The associated stochastic processes belong to the class of self-interacting Markov chains. In contrast to traditional Markov chains, their time evolution depend on the occupation measure of their past values. This general methodology allows us to provide a natural way to sample from a sequence of target probability measures of increasing complexity. We develop an original theoretical analysis to analyze the behaviour of these iterative algorithms. We establish a variety of convergence results including exponential estimates and a uniform convergence theorem with respect to the number of target distributions. We also illustrate these algorithms in the context of Feynman-Kac distribution flows.
(this is joint work with Professor Pierre Del Moral)
[ 講演参考URL ]
https://www.ms.u-tokyo.ac.jp/~kengok/statseminar/2009/02.html