## 過去の記録

#### 代数学コロキウム

16:40-17:40   数理科学研究科棟(駒場) 056号室

Special values of zeta functions of singular varieties over finite fields via higher chow groups (JAPANESE)

### 2013年05月14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 cycles and homotopies of wrinkled fibrations (JAPANESE)
[ 講演概要 ]
Wrinkled fibrations on closed 4-manifolds are stable
maps to closed surfaces with only indefinite singularities. Such
fibrations and variants of them have been studied for the past few years
to obtain new descriptions of 4-manifolds using mapping class groups.
Vanishing cycles of wrinkled fibrations play a key role in these studies.
In this talk, we will explain how homotopies of wrinkled fibrtions affect
their vanishing cycles. Part of the results in this talk is a joint work
with Stefan Behrens (Max Planck Institute for Mathematics).

#### 講演会

16:30-18:00   数理科学研究科棟(駒場) 118号室
5/10(金) 5/14(火) 5/21(火) 5/24(金)の4回連続講演です。部屋と時間は毎回同じです

Laurent Lafforgue 氏 (IHES)
Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)

### 2013年05月13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

Geometry and analysis of isolated essential singularities and their applications (JAPANESE)
[ 講演概要 ]
We establish a rescaling principle for isolated essential singularities of holomorphic curves and quasiregular mappings, and gives several applications of it in the theory of value distribution and dynamics. This is a joint work with Pekka Pankka.

### 2013年05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

Symplectic-orthogonal theta lifts and explicit formulas for archimedean Whittaker functions (JAPANESE)

Mumford形式の無限積表示とSelbergゼータ値への応用 (JAPANESE)
[ 講演概要 ]

#### 東京無限可積分系セミナー

10:30-12:00   数理科学研究科棟(駒場) 117号室
Anatol Kirillov 氏 (RIMS Kyoto Univ.)
Saga of Dunkl elements (ENGLISH)
[ 講演概要 ]
The Dunkl operators has been introduced by C. Dunkl in the middle of
80's of the last century as a powerful mean in the study of orthogonal
polynomials related with finite Coxeter groups. Later it was discovered
a deep connection of the the Dunkl operators with the theory of
Integrable systems and Invariant Theory.
In my talk I introduce and study a certain class of nonhomogeneous
quadratic algebras together with the distinguish set of mutually
commuting elements inside of each, the so-called universal Dunkl elements.
The main problem I would like to discuss is : What is the algebra
generated by universal Dunkl elements in a different representations of
I'm planning to present partial answers on that problem related with
classical and quantum Schubert and Grothendieck Calculi as well as the
theory of elliptic series.
Also some interesting algebraic properties of the quadratic algebra(s)
in question will be described.

### 2013年05月10日(金)

#### 講演会

16:30-18:00   数理科学研究科棟(駒場) 118号室
5/10(金) 5/14(火) 5/21(火) 5/24(金)の4回連続講演です。

Laurent Lafforgue 氏 (IHES)
Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)

### 2013年05月09日(木)

#### 幾何コロキウム

10:00-11:30   数理科学研究科棟(駒場) 122号室

[ 講演概要 ]

### 2013年05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) 118号室
Paul Muhly 氏 (University of Iowa)
Boundaries for Tensor Algebras (ENGLISH)

### 2013年05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

Homological intersection in braid group representation and dual
Garside structure (JAPANESE)
[ 講演概要 ]
One method to construct linear representations of braid groups is to use
an action of braid groups on certain homology of local system coefficient.
Many famous representations, such as Burau or Lawrence-Krammer-Bigelow
representations are constructed in such a way. We show that homological
intersections on such homology groups are closely related to the dual
Garside structure, a remarkable combinatorial structure of braid, and
prove that some representations detects the length of braids in a
surprisingly simple way.
This work is partially joint with Bert Wiest (Univ. Rennes1).

#### 数値解析セミナー

16:30-18:00   数理科学研究科棟(駒場) 123号室

[ 講演概要 ]

この講演では、まず外接半径条件とそれに関する数値実験の結果を示し、「外接半径条件によりわかったこと」、「外接半径条件でも説明がつかないこと」を説明する。さらに、外接半径条件の発見から派生した諸問題、あるいは有限要素解析の数学的基礎理論において、現在においても未解決な問題について解説し、特に若い研究者の注意を喚起したい。
[ 講演参考URL ]
http://www.infsup.jp/utnas/

### 2013年04月30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

The homomorphisms between scalar generalized Verma modules of gl(n,C) with regular infinitesimal characters (JAPANESE)
[ 講演概要 ]
We will explain the classification of the homomorphisms between scalar generalized Verma modules of gl(n,C) with regular infinitesimal characters. In fact, they are compositions of elementary homomorphisms. The main ingredient of our proof is the translation principle in the mediocre region.

#### 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
Francis Sergeraert 氏 (L'Institut Fourier, Univ. de Grenoble)
Discrete vector fields and fundamental algebraic topology.
(ENGLISH)
[ 講演概要 ]
Robin Forman invented the notion of Discrete Vector Field in 1997.
A recent common work with Ana Romero allowed us to discover the notion
of Eilenberg-Zilber discrete vector field. Giving the topologist a
totally new understanding of the fundamental tools of combinatorial
algebraic topology: Eilenberg-Zilber theorem, twisted Eilenberg-Zilber
theorem, Serre and Eilenberg-Moore spectral sequences,
Eilenberg-MacLane correspondence between topological and algebraic
classifying spaces. Gives also new efficient algorithms for Algebraic
Topology, considerably improving our computer program Kenzo, devoted
to Constructive Algebraic Topology. The talk is devoted to an
introduction to discrete vector fields, the very simple definition of
the Eilenberg-Zilber vector field, and how it can be used in various
contexts.

### 2013年04月24日(水)

#### 代数学コロキウム

17:30-18:30   数理科学研究科棟(駒場) 056号室

Good reduction of ramified affinoids in the Lubin-Tate perfectoid space (ENGLISH)
[ 講演概要 ]
Recently, Weinstein finds some affinoids in the Lubin-Tate perfectoid space and computes their reduction in equal characteristic case. The cohomology of the reduction realizes the local Langlands correspondence for some representations of GL_h, which are unramified in some sense. In this talk, we introduce other affinoids in the Lubin-Tate perfectoid space in equal characteristic case, whose reduction realizes "ramified" representations of conductor exponent h+1. We call them ramified affinoids. We study the cohomology of the reduction and its relation with the local Langlands correspondence. This is a joint work with Takahiro Tsushima.

(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.)

#### Kavli IPMU Komaba Seminar

17:00-18:30   数理科学研究科棟(駒場) 002号室

Calabi-Yau threefolds of Type K (ENGLISH)
[ 講演概要 ]
We will provide a full classification of Calabi-Yau threefolds of Type
K studied by Oguiso and Sakurai. Our study completes the
classification of Calabi-Yau threefolds with infinite fundamental
group. I will then discuss special Lagrangian T3-fibrations of
Calabi-Yau threefolds of type K. This talk is based on a joint work
with Kenji Hashimoto.

### 2013年04月23日(火)

#### 数値解析セミナー

16:30-18:00   数理科学研究科棟(駒場) 002号室

[ 講演概要 ]

[ 講演参考URL ]
http://www.infsup.jp

#### 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
Andrei Pajitnov 氏 (Univ. de Nantes)
Twisted Novikov homology and jump loci in formal and hyperformal spaces (ENGLISH)
[ 講演概要 ]
Let X be a CW-complex, G its fundamental group, and R a repesentation of G.
Any element of the first cohomology group of X gives rise to an exponential
deformation of R, which can be considered as a curve in the space of
representations. We show that the cohomology of X with local coefficients
corresponding to the generic point of this curve is computable from a spectral
sequence starting from the cohomology of X with R-twisted coefficients. We
compute the differentials of the spectral sequence in terms of Massey products,
and discuss some particular cases arising in Kaehler geometry when the spectral
sequence degenerates. We explain the relation of these invariants and the
twisted Novikov homology. This is a joint work with Toshitake Kohno.

### 2013年04月22日(月)

#### 講演会

16:45-18:15   数理科学研究科棟(駒場) 126号室
Stefano Olla 氏 (Univ. Paris-Dauphine)
Thermal conductivity and weak coupling (ENGLISH)
[ 講演概要 ]
We investigate the macroscopic thermal conductivity of a chain of anharmonic oscillators and more general systems, under weak coupling limits and energy conserving stochastic perturbations of the dynamics. In particular we establish a series expansion in the coupling parameter.

#### 代数幾何学セミナー

16:30-18:00   数理科学研究科棟(駒場) 118号室
Professor Igor Reider 氏 (Universite d'Angers / RIMS)
Kodaira-Spencer classes, geometry of surfaces of general type and Torelli
theorem (ENGLISH)
[ 講演概要 ]
In this talk I will explain a geometric interpretation of Kodaira-Spencer classes and apply
it to the study of the differential of the period map of weight 2 Hodge structures for surfaces
of general type.
My approach is based on interpreting Kodaira-Spencer classes as higher rank bundles and
then studing their stability. This naturally leads to two parts:
1) unstable case
2) stable case.
I will give a geometric characterization of the first case and show how to relate the second
case to a special family of vector bundles giving rise to a family of rational curves. This family
of rational curves is used to recover the surface in question.

#### 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

Kobayashi hyperbolic imbeddings into low degree surfaces in three dimensional projective spaces (JAPANESE)
[ 講演概要 ]
We construct smooth irreducible curves of the lowest possible degree in quadric and cubic surfaces whose complements are Kobayashi hyperbolically imbedded into those surfaces. This is a joint work with Atsushi Ito.

### 2013年04月20日(土)

#### 調和解析駒場セミナー

13:00-18:00   数理科学研究科棟(駒場) 128号室
このセミナーは,月に1度程度,不定期に開催されます.

Directional maximal operators and radial weights on the plane
(JAPANESE)
[ 講演概要 ]
Let $\\Omega$ be a set of unit vectors and $w$ be a radial weight on the plane. We consider the weighted directional maximal operator defined by
$M_{\\Omega,w}f(x):=\\sup_{x\\in R\\in \\cB_{\\Omega}}\\frac{1}{w(R)}\\int_{R}|f(y)|w(y)dy$,
where $\\cB_{\\Omega}$ denotes the all rectangles on the plane whose longest side is parallel to some unit vector in $\\Omega$ and $w(R)$ denotes $\\int_{R}w$.
In this talk we give a sufficient condition of the weight
for an almost-orthogonality principle related to these maximal operators to hold. The condition allows us to get weighted norm inequality
$\\|M_{\\Omega,w}f\\|_{L^2(w)}\\le C \\log N \\|f\\|_{L^2(w)}$,
when $w(x)=|x|^a$, $a>0$, and $\\Omega$ is a set of unit vectors on the plane with cardinality $N\\gg 1$.

[ 講演概要 ]

### 2013年04月19日(金)

#### PDE実解析研究会

10:30-11:30   数理科学研究科棟(駒場) 056号室

An approximation scheme for the anisotropic and the planar crystalline curvature flow (JAPANESE)
[ 講演概要 ]
In 2004 Chambolle proposed an algorithm for the mean curvature flow based on a variational problem. Since then, some extensions of his algorithm have been studied.
In this talk we would like to discuss the convergence of the anisotropic variant of his algorithm by use of the anisotropic signed distance function. An application to the approximation for the planar motion by crystalline curvature is also discussed.

### 2013年04月18日(木)

#### 幾何コロキウム

10:00-11:30   数理科学研究科棟(駒場) 122号室

Harmonic maps into Grassmannian manifolds (JAPANESE)
[ 講演概要 ]
A harmonic map from a Riemannian manifold into a Grassmannian manifold is characterized by a vector bundle, a space of sections of the bundle and the Laplace operator. This characterization can be considered as a generalization of Theorem of Takahashi on minimal immersions into a sphere (J.Math.Soc.Japan 18 (1966)) and implies the well-known fact that the Kodaira embedding is a harmonic map.

We apply the main result to generalize a Theorem of do Carmo and Wallach (Ann.of Math. 93 (1971)) and describe a moduli space of harmonic maps with constant energy densities and some properties about pull-back bundles and connections from a Riemannian homogeneous space into a Grassmannian. We give some applications including a rigidity of minimal immersions from the complex projective line to complex projective spaces (S.Bando and Y.Ohnita, J. Math. Soc. Japan 39 (1987)).

The ADHM-construction of instantons gives a family of maps into Grassmannians via monad theory on the twistor space. These maps are, in general, not harmonic maps, but are similar to maps obtained in our generalized do Carmo-Wallach theorem. We compare these two constructions of moduli spaces.

### 2013年04月17日(水)

#### 作用素環セミナー

16:30-18:00   数理科学研究科棟(駒場) 118号室
Tamar Friedmann 氏 (Univ. Rochester)
Singularities, algebras, and the string landscape (ENGLISH)

### 2013年04月16日(火)

#### Lie群論・表現論セミナー

16:30-18:30   数理科学研究科棟(駒場) 126号室
Michael Pevzner 氏 (Reims University) 16:30-17:30
Non-standard models for small representations of GL(n,R) (ENGLISH)
[ 講演概要 ]
We shall present new models for some parabolically induced
unitary representations of the real general linear group which involve Weyl symbolic calculus and furnish very efficient tools in studying branching laws for such representations.
Pierre Clare 氏 (Penn. State University, USA) 17:30-18:30
Degenerate principal series of symplectic groups (ENGLISH)
[ 講演概要 ]
We will discuss properties of representations of symplectic groups induced from maximal parabolic subgroups of Heisenberg type, including K-types formulas, expressions of intertwining operators and the study of their spectrum.