## 過去の記録

#### 古典解析セミナー

16:00-17:00   数理科学研究科棟(駒場) 117号室
Whittaker functions and Barnes-Type Lemmas (ENGLISH)
[ 講演概要 ]
In the theory of automorphic forms on GL(n,R), which concerns harmonic analysis and representation theory of this group, certain special functions known as GL(n,R) Whittaker functions play an important role. These Whittaker functions are generalizations of classical Whittaker (or, more specifically, Bessel) functions.

Mellin transforms of products of GL(n,R) Whittaker functions may be expressed as certain Barnes type integrals, or equivalently, as hypergeometric series of unit argument. The general theory of automorphic forms predicts that these Mellin transforms reduce, in certain cases, to products of gamma functions. That this does in fact occur amounts to a whole family of generalizations of the so-called Barnes' Lemma and Barnes' Second Lemma, from the theory of hypergeometric series. We will explore these generalizations in this talk.

This talk will not require any specific knowledge of automorphic forms.

### 2014年10月28日(火)

#### 代数学コロキウム

16:40-18:50   数理科学研究科棟(駒場) 002号室
いつもと曜日が異なりますのでご注意下さい
Judith Ludwig 氏 (Imperial college) 16:40-17:40
[ 講演概要 ]
Let B be a definite quaternion algebra over the rationals, G the algebraic group defined by the units in B and H the subgroup of G of norm one elements. Then the classical transfer of automorphic representations from G to H is well understood thanks to Labesse and Langlands, who proved formulas for the multiplicity of irreducible admissible representations of H(adeles) in the discrete automorphic spectrum.
The goal of this talk is to prove a p-adic version of this transfer. By this we mean an extension of the classical transfer to p-adic families of automorphic forms as parametrized by certain rigid analytic spaces called eigenvarieties. We will prove the p-adic transfer by constructing a morphism between eigenvarieties, which agrees with the classical transfer on points corresponding to classical automorphic representations.
Jan Nekovar 氏 (Université Paris 6) 17:50-18:50
Plectic cohomology (English)

### 2014年10月27日(月)

#### 代数幾何学セミナー

14:50-16:20   数理科学研究科棟(駒場) 122号室
いつもと開始時間が異なります。
Meng Chen 氏 (Fudan University)
On projective varieties with very large canonical volume (ENGLISH)
[ 講演概要 ]
For any positive integer n>0, a theorem of Hacon-McKernan, Takayama and Tsuji says that there is a constant c(n) so that the m-canonical map is birational onto its image for all smooth projective n-folds and all m>=c(n). We are interested in the following problem "P(n)": is there a constant M(n) so that, for all smooth projective n-fold X with Vol(X)>M(n), the m-canonical map of X is birational for all m>=c(n-1). The answer to “P_n" is positive due to Bombieri when $n=2$ and to Todorov when $n=3$. The aim of this talk is to introduce my joint work with Zhi Jiang from Universite Paris-Sud. We give a positive answer in dimensions 4 and 5.

#### 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

On the minimality of canonically attached singular Hermitian metrics on certain nef line bundles (JAPANESE)
[ 講演概要 ]
We apply Ueda theory to a study of singular Hermitian metrics of a (strictly) nef line bundle $L$. Especially we study minimal singular metrics of $L$, metrics of $L$ with the mildest singularities among singular Hermitian metrics of $L$ whose local weights are plurisubharmonic. In some situations, we determine a minimal singular metric of $L$. As an application, we give new examples of (strictly) nef line bundles which admit no smooth Hermitian metric with semi-positive curvature.

### 2014年10月25日(土)

#### 調和解析駒場セミナー

13:30-16:30   数理科学研究科棟(駒場) 128号室

Approximation in Banach space by linear positive operators (JAPANESE)
[ 講演概要 ]
We obtain a sufficient condition for the
convergence of positive linear operators in Banach
function spaces on Rn and derive a Korovkin type
theorem for these spaces. Also, we generalized
this result via statistical sense. This is a joint

Local ill-posedness of the Euler equations in a critical Besov space (JAPANESE)
[ 講演概要 ]

がなされてきているが、$H^{d/2+1}$や$W^{d/p+1,p}$ ($d$は

ついては未解決であった。昨年、BourgainとLiは$H^{d/2+1}$や
$W^{d/p+1,p}$でオイラー方程式が局所非適切であることを証明した。

するより精密な評価を進めており、実解析的にも大変興味深い。

この先駆的な結果を追うようにして、$C^1$クラスでの非適切性に関
しても3つの研究グループによって（それぞれ独自の手法によって）

Bourgain-Li May12)本講演では、解の存在と一意性が成り立って
いる$B^1_{¥infty,1}$というBesov空間(Pak-Park,2004）で

### 2014年10月22日(水)

#### 作用素環セミナー

16:30-18:00   数理科学研究科棟(駒場) 122号室

Free independence in ultraproduct von Neumann algebras and applications (ENGLISH)

#### 数理人口学・数理生物学セミナー

14:50-16:20   数理科学研究科棟(駒場) 122号室

[ 講演概要 ]

$({\rm P})^k \left\{ \begin{array}{ll} u_t=\Delta u- ku^{m_1}v^{m_3} \quad\quad & \mbox{in} \ Q_T:=\Omega \times (0, T), \\ v_t= -ku^{m_2}v^{m_4} \quad\quad&\mbox{in} \ Q_T, \\ \dfrac{\partial u}{\partial \nu}=0 \quad\quad&\mbox{on} \ S_T:=\partial \Omega \times (0, T), \\ u(x,0)=u_{0}(x),\quad v(x,0)=v_{0}(x) \quad\quad&\mbox{in} \ \Omega, \\ \end{array} \right.$

ただし、$\Omega$は$\mathbf{R}^n$の有界領域, $T$は正定数, $\nu$は$\partial \Omega$上の外向き単位法線ベクトル、$m_i(i=1,2,3,4)$は$1$より大きい正定数、$u_0, v_0$は非負の初期値を表す。このとき、適当な初期条件のもとで$k\to \infty$としたとき、次のような結果を得た(詳細は講演内で述べる):
$\begin{array}{cll} &\mbox{ (Case I)}\quad & {\bf m}=(m_1, 1, 1, 1)かつm_1> 3 \ &\Rightarrow \ uは\mbox{\Omega}上の熱方程式の解に近づく \\ &\mbox{ (Case II)}& {\bf m}=(1, m_2, 1, 1) かつm_2 >2 \ &\Rightarrow \ uは{\rm supp}\, u_0上の熱方程式の解に近づく \\ &\mbox{ (Case III)}& {\bf m}=(1, 1, m_3, 1)かつm_3> 0 &\Rightarrow \ uは一相{\rm Stefan}問題の解に近づく \\ &\mbox{ (Case IV)}& {\bf m}=(1, 1, 1, m_4)かつ2>m_4> 1 &\Rightarrow \ uは一相{\rm Stefan}問題の解に近づく \\ \end{array}$

### 2014年10月21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

Vanishing theorems for p-local homology of Coxeter groups and their alternating subgroups (JAPANESE)
[ 講演概要 ]
Given a prime number $p$, we estimate vanishing ranges of $p$-local homology groups of Coxeter groups (of possibly infinite order) and alternating subgroups of finite reflection groups. Our results generalize those by Nakaoka for symmetric groups and Kleshchev-Nakano and Burichenko for alternating groups. The key ingredient is the equivariant homology of Coxeter complexes.

### 2014年10月20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

IV型モジュラー多様体の小平次元 (JAPANESE)
[ 講演概要 ]

#### 数値解析セミナー

16:30-18:00   数理科学研究科棟(駒場) 056号室

Finite element method with various types of penalty on domain/boundary (ENGLISH)
[ 講演概要 ]
We are concerned with several penalty methods (on domain/boundary)
combining with finite element method to solve some partial differential equations. The penalty methods are very useful and widely applied to various problems. For example, to solve the Navier-Stokes equations in moving boundary domain, the finite element method requires to construct the boundary fitted mesh at every times step, which is very time-consuming. The fictitious domain method is proposed to tackle this problem. It is to reformulate the equation to a larger fixed domain, called the fictitious domain, to which we can take a uniform mesh independent on the original moving boundary. The reformulation is based on a penalty method on do- main. Some penalty methods are proposed to approximate the boundary conditions which are not easy to handle with general FEM, such as the slip boundary condition to Stokes/Navier-Stokes equations, the unilateral boundary condition of Signorini’s type to Stokes equations, and so on. It is known that the variational crimes occurs if the finite element spaces or the implementation methods are not chosen properly for slip boundary condition. By introducing a penalty term to the normal component of velocity on slip boundary, we can solve the equations in FEM easily. For the boundary of Signorini’s type, the variational form is an inequality, to which the FEM is not easy to applied. However, we can approximate the variational inequality by a variation equation with penalty term, which can be solve by FEM directly. In above, we introduced several penalty methods with finite element approximation. In this work, we investigate the well-posedness of those penalty method, and obtain the error estimates of penalty; moreover, we consider the penalty methods combining with finite element approximation and show the error estimates.

### 2014年10月17日(金)

#### 幾何コロキウム

10:00-11:30   数理科学研究科棟(駒場) 126号室

A finite diameter theorem on RCD spaces (JAPANESE)
[ 講演概要 ]

### 2014年10月15日(水)

#### 作用素環セミナー

16:30-18:00   数理科学研究科棟(駒場) 122号室

Classification of actions of compact abelian groups on subfactors with index less than 4 (ENGLISH)

### 2014年10月14日(火)

#### 諸分野のための数学研究会

10:30-11:30   数理科学研究科棟(駒場) 056号室

Fluid flow and electromagnetic fields, from viewpoint of theoretical physics -- Is the Navier-Stokes Equation sufficient to describe turbulence at very high Reynolds numbers? -- (JAPANESE)
[ 講演概要 ]
There exists analogy between the fluid flow and electromagnetic fields with respect to their mathematical representations. This is reasonable because both are continuous physical fields having energy and momentum in space-time. In particular, fluid’s vorticity is analogous to magnetic field.

On the other hand, for simulation of atmospheric global motion on the giant computer Earth Simulator, many empirical physical parameters must be introduced in order to obtain realistic results for weather prediction, etc. This implies that the present system of equations of fluid flows may not be sufficient to describe fluid motions of large scales at very high Reynolds numbers. We consider whether the above-mentioned analogy is useful for improvement of the theory of turbulence at very high Reynolds numbers.

#### 代数学コロキウム

17:30-18:30   数理科学研究科棟(駒場) 002号室
いつもと曜日が違いますのでご注意ください.
Fabrizio Andreatta 氏 (Università Statale di Milano)
A p-adic criterion for good reduction of curves (ENGLISH)
[ 講演概要 ]
Given a curve over a dvr of mixed characteristic 0-p with smooth generic fiber and with semistable reduction, I will present a criterion for good reduction in terms of the (unipotent) p-adic étale fundamental group of its generic fiber.

(本講演は「東京北京パリ数論幾何セミナー」として, インターネットによる東大数理, Morningside Center of MathematicsとIHESの双方向同時中継で行います.)

### 2014年10月11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

$SU(3,1)$ の離散系列表現の第2種の行列係数について(宮崎直君の計算に基づく) (JAPANESE)
[ 講演概要 ]
Whittaker関数の場合、「第2種」と呼んでいるものがある。少なくとも正則でない離散系列表現の場合にも同等なものがあるように見える。それについて簡単に問題を述べる

$Sp(2, R)$ 上の保型形式のFourier展開に向けて (JAPANESE)
[ 講演概要 ]
(largeと呼ばれる)正則でない離散系列表現を生成する尖点形式の極小放物型部分群に対するFourier展開を考えます。Fourier展開を構成する関数(の空間)は,偏微分方程式系で特徴付けられることが知られています。ここでは,既に得られているWhittaker関数以外の部分について,偏微分方程式系を満たす具体的な関数が見つかったので紹介します。これらは,ある条件の下では,定数倍を除き一意的であることがわかります

### 2014年10月10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 ]

まず,志村多様体の局所類似がどのようなものか,また,そのエタールコホモロジーが局所ラングランズ対応とどのように関係すると期待されているかについて,なるべく平易に述べる.

### 2014年10月08日(水)

#### 作用素環セミナー

16:30-18:00   数理科学研究科棟(駒場) 122号室

Realization of hyperbolic group $C^*$-algebras as decreasing intersection of Cuntz algebras $O_2$ (ENGLISH)

#### 数理人口学・数理生物学セミナー

14:50-16:20   数理科学研究科棟(駒場) 128号室

[ 講演概要 ]

が無毒化される効果を含めた系のダイナミクスも, 現地での研究討論によって得た課題として併せて紹介する.

### 2014年10月07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

Transversality problems in string topology and de Rham chains (JAPANESE)
[ 講演概要 ]
ストリング・トポロジーの出発点は,多様体の自由ループ空間のホモロジーの上にBatalin-Vilkovisky(BV)代数の構造を発見したChas-Sullivanの仕事である.
この結果を精密化して鎖レベルの構造を定義することは重要な問題であるが,まだ決定版の解答は得られていない.困難の一つは,交叉積を鎖レベルで定義する際に現れる,横断正則性の問題である.

### 2014年10月03日(金)

#### 東京無限可積分系セミナー

13:30-17:00   数理科学研究科棟(駒場) 002号室

KPZ方程式とMacdonald過程 (JAPANESE)
[ 講演概要 ]
Kardar-Parisi-Zhang(KPZ)方程式は、1986年界面の成長を記述するモデル方程式として導入された非線形確率偏微分方程式である。
2010年、wedge型の初期条件の場合に厳密解が見いだされ、その後種々の一般化が行われるとともに、その可解構造に対する理解が深められつつある。特にBorodinとCorwinはMacdonald過程と呼ばれるSchur過程の一般化を導入し、KPZ方程式の離散模型に対しても行列式構造があることを見いだした。本講演ではこれらの発展について解説する。

Entanglement spectra in topological phases and coupled Tomonaga-Luttinger liquids (JAPANESE)
[ 講演概要 ]
The entanglement spectrum (ES) has been found to provide useful probes of topological phases of matter and other exotic strongly correlated states. For the system's ground state, the ES is defined as the full eigenvalue spectrum of the reduced density matrix obtained by tracing out the degrees of freedom in part of the system. A key result observed in various topological phases and other gapped systems has been the remarkable correspondence between the ES and the edge-state spectrum. While this correspondence has been analytically proven for some topological phases, it is interesting to ask what systems show this correspondence more generally and how the ES changes when the bulk energy gap closes.

We here study the ES in two coupled Tomonaga-Luttinger liquids (TLLs) on parallel periodic chains. In addition to having direct applications to ladder systems, this problem is closely related to the entanglement properties of two-dimensional topological phases. Based on the calculation for coupled chiral TLLs, we provide a simple physical proof for the correspondence between edge states and the ES in quantum Hall systems consistent with previous numerical and analytical studies. We also discuss violations of this correspondence in gapped and gapless phases of coupled non-chiral TLLs.

Reference: R. Lundgren, Y. Fuji, SF, and M. Oshikawa, Phys. Rev. B 88, 245137 (2013).

### 2014年10月02日(木)

#### 作用素環セミナー

16:30-18:00   数理科学研究科棟(駒場) 126号室
Hanfeng Li 氏 (SUNY Buffalo)
Entropy and $L^2$-torsion (ENGLISH)

### 2014年10月01日(水)

#### 作用素環セミナー

16:30-18:00   数理科学研究科棟(駒場) 122号室
Serge Richard 氏 (Nagoya Univ.)
Back-and-forth between scattering theory and index theorems (ENGLISH)

### 2014年09月22日(月)

#### 東京無限可積分系セミナー

13:30-16:00   数理科学研究科棟(駒場) 117号室
Satoshi Nawata 氏 (Theoretical Physics at NIKHEF)
Colored HOMFLY homology of knots and links (ENGLISH)
[ 講演概要 ]
In this talk I will present structural properties of colored HOMFLY homology of knots and links. These rich properties of the categorification of the colored HOMFLY polynomial are obtained by using various methods: physics insights, representation theory of Lie super-algebras, double affine Hecke algebras, etc. This in turn enables computation of colored HOMFLY homology for various classes of knots and links and consequent computation of super-A-polynomial - the deformation of the classical A-polynomial. I will also explain recent results and special additional properties for colored Kauffman homology as well as the case of links. Although I will try to give a talk accessible to mathematicians, there is no proof and rigorousness in this talk.

### 2014年09月19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) 大講義室号室
お茶&Coffee&お菓子: 16:00～16:30 (コモンルーム)
Etienne Ghys 氏 (École normale supérieure de Lyon)
William Thurston and foliation theory (ENGLISH)
[ 講演概要 ]
Between 1972 and 1976, William Thurston revolutionized foliation theory. Twenty years later, he described this period of his mathematical life in a remarkable paper « On proofs and progress in mathematics ». In this talk, I will begin by a general overview of some of Thurston's contribution to this theory. I will then describe some of the current development.

#### FMSPレクチャーズ

14:30-16:00   数理科学研究科棟(駒場) 128号室
Victoria Lebed 氏 (Osaka City University, JSPS)
A bridge between knotted graphs and axiomatizations of groups (ENGLISH)
[ 講演概要 ]
This talk will be devoted to a new algebraic structure called qualgebra. From the topological viewpoint, our construction is motivated by a study of knotted 3-valent graphs via combinatorially defined coloring invariants. From the algebraic viewpoint, it gives a part of an alternative axiomatization of groups, describing the properties of the conjugation operation and its interactions with the group multiplication. Explicit examples of qualgebras and associated graph invariants will be given.
[ 講演参考URL ]
http://fmsp.ms.u-tokyo.ac.jp/FMSPLectures_Lebed.pdf