過去の記録 ~11/11本日 11/12 | 今後の予定 11/13~



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
北山 貴裕 氏 (東京大学大学院数理科学研究科)
Torsion volume forms and twisted Alexander functions on
character varieties of knots

[ 講演概要 ]
Using non-acyclic Reidemeister torsion, we can canonically
construct a complex volume form on each component of the
lowest dimension of the $SL_2(\\mathbb{C})$-character
variety of a link group.
This volume form enjoys a certain compatibility with the
following natural transformations on the variety.
Two of them are involutions which come from the algebraic
structure of $SL_2(\\mathbb{C})$ and the other is the
action by the outer automorphism group of the link group.
Moreover, in the case of knots these results deduce a kind
of symmetry of the $SU_2$-twisted Alexander functions
which are globally described via the volume form.


16:30-18:00   数理科学研究科棟(駒場) 128号室
Ivana Alexandrova 氏 (東京大数理)
The Structure of the Scattering Amplitude for Schrodinger Operators with a Strong Magnetic Field
[ 講演概要 ]
We study the microlocal structure of the semi-classical scattering amplitude for Schrodinger operators with a strong magnetic field at non-trapping energies. We prove that, up to any order, the scattering amplitude can be approximated by a semi-classical pseudodifferential-operator-valued Fourier integral operator.



10:30-12:00   数理科学研究科棟(駒場) 126号室
藤木 明 氏 (大阪大学)


16:30-18:00   数理科学研究科棟(駒場) 126号室
大川 領 氏 (東京工業大学)
Moduli on the projective plane and the wall-crossing
[ 講演概要 ]
射影平面上の半安定層のモジュライ空間を、Bridgeland 安定性条件
により、壁越え現象としてのflip の記述を得る。
応用として、flip のBetti 数などが計算できる。



16:30-18:00   数理科学研究科棟(駒場) 056号室
鈴木章斗 氏 (九州大学数理学研究院)
Infrared divergence of scalar quantum field model on pseudo Riemann manifold



16:30-18:45   数理科学研究科棟(駒場) 056号室
Vincent Maillot 氏 (Paris第7大学) 16:30-17:30
New algebraicity results for analytic torsion
Richard Hain 氏 (Duke大学) 17:45-18:45
On the Section Conjecture for the universal curve over function fields


10:30-11:30   数理科学研究科棟(駒場) 056号室
Winston Ou 氏 (Scripps College / currently visiting assistant professor at Keio University)
Monge-Ampere equations, the Bellman Function Technique, and Muckenhoupt weights
[ 講演概要 ]
In the last few years several classical results in harmonic analysis (in particular, the study of $A_\\infty$ weights have been sharpened with the use of a version of the Bellman function method (promulgated by Nazarov, Treil, and Volberg in the 90's) that involves recognizing the Bellman function as the solution of a Monge-Ampere PDE (the method was introduced by Vasyunin in 2003). We will give a sketch of the modified technique, outline some recent work-in-progress (with Slavin and Wall) using the technique in $A_\\infty$, and then present a few related problems.


15:30-17:00   数理科学研究科棟(駒場) 122号室
柳尾 朋洋 氏 (早大 基幹理工)
[ 講演概要 ]



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
久野 雄介 氏 (東京大学大学院数理科学研究科)
The Meyer functions for projective varieties and their applications
[ 講演概要 ]
Meyer function is a kind of secondary invariant related to the signature
of surface bundles over surfaces. In this talk I will show there exist uniquely the Meyer function
for each smooth projective variety.
Our function is a class function on the fundamental group of some open algebraic variety.
I will also talk about its application to local signature for fibered 4-manifolds


16:30-18:00   数理科学研究科棟(駒場) 126号室
岸本崇氏 氏 (埼玉大学理工学研究科)
Group actions on affine cones
[ 講演概要 ]
The action of the additive group scheme C_+ on normal affine varieties is one of main subjects in affine algebraic geometry for a long time. In this talk, we shall mainly consider the problem about the existence of C_+-actions on affine cones, more precisely, the question:

"Determine the affine cones over smooth projective varieties admitting a (non-trivial) C_+-action ".

This question has an interest from a point of view of singularities. Indeed, a normal Cohen-Macaulay affine variety admitting an action by C_+ has at most rational singularities due to the result of H. Flenner and M. Zaidenberg. In the case of dimension 2, any affine cone over the projective line P^1 has a cyclic quotient singularity, and we can see that it admits, in fact, a C_+-action. Meanwhile, in case of dimension 3, i.e., affine cones over rational surfaces, the situation becomes more subtle.

One of the main results is concerned with a criterion for the existence of a C_+-action on affine cones (of any dimension) in terms of a cylinderlike open subset on the base variety. By making use of it, it is shown that, for any rational surface Y, we can take a suitable embedding of Y in such a way that the associated affine cone admits an action of C_+. Furthermore we are able to confirm that an affine cone over an anticanonically embedded del Pezzo surface of degree greater than or equal to 4 also admits such an action.

Nevertheless, our final purpose to decide whether or not there does exist a C_+-action on the fermat cubic: x^3+y^3+z^3+u^3 =0 in C^4, which is the affine cone over an anticanonically embedded cubic surface, say Y_3, is not yet accomplished. But, we can obtain certain informations about a linear pencil of rational curves on Y_3 arising from a C_+-action which seem to be useful in order to deny an existence of an action of C_+.



10:30-12:00   数理科学研究科棟(駒場) 126号室
早乙女飛成 氏 (筑波大学)



13:30-16:00   数理科学研究科棟(駒場) 123号室
小池 健二 氏 (山梨大学教育人間科学部) 13:30-14:30
成田宏秋 氏 (熊本大学理学部) 15:00-16:00
Fourier coefficients of Arakawa lifting and some degree eight L-function

[ 講演概要 ]


11:00-12:00   数理科学研究科棟(駒場) 117号室
有田親史 氏 (九大数理)
[ 講演概要 ]
非対称単純排他過程(asymmetric simple exclusion process, ASEP)と呼ばれ



16:30-18:00   数理科学研究科棟(駒場) 056号室
河東泰之 氏 (東大数理)
The super Virasoro algebra and noncommutative geometry



10:30-11:30   数理科学研究科棟(駒場) 056号室
小磯深幸 氏 (奈良女子大学理学部/JSTさきがけ)
Variational problems for anisotropic surface energies
[ 講演概要 ]
A surface energy is anisotropic if it depends on the direction of the surface. The minimizer of an anisotropic surface energy among all closed surfaces enclosing a fixed volume is called the Wulff shape. We will discuss the characterization of the Wulff shape, the uniqueness and stability of solutions to variational problems for anisotropic surface energy with several boundary conditions.



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
佐藤 正寿 氏 (東京大学大学院数理科学研究科)
The abelianization of the level 2 mapping class group
[ 講演概要 ]
The level d mapping class group is a finite index subgroup of the mapping class group of an orientable closed surface. For d greater than or equal to 3, the abelianization of this group is equal to the first homology group of the moduli space of nonsingular curves with level d structure.
In this talk, we determine the abelianization of the level d mapping class group for d=2 and odd d. For even d greater than 2, we also determine it up to a cyclic group of order 2.



10:30-12:00   数理科学研究科棟(駒場) 126号室
野口潤次郎 氏 (東京大学)
A unicity theorem and Erdös' problem for polarized semi-abelian varieties (joint with P. Corvaja)


16:30-18:00   数理科学研究科棟(駒場) 126号室
Vladimir P. Kostov 氏 (Nice大学)
On the Schur-Szeg\\"o composition of polynomials
[ 講演概要 ]
The Schur-Szeg\\"o composition of the degree $n$ polynomials $P:=\\sum_{j=0}^na_jx^j$ and $Q:=\\sum_{j=0}^nb_jx^j$ is defined by the formula $P*Q:=\\sum_{j=0}^na_jb_jx^j/C_n^j$ where $C_n^j=n!/j!(n-j)!$. Every degree $n$ polynomial having one of its roots at $-1$ (i.e. $P=(x+1)(x^{n-1}+c_1x^{n-2}+\\cdots +c_{n-1})$) is representable as a Schur-Szeg\\"o composition of $n-1$ polynomials of the form $(x+1)^{n-1}(x+a_i)$ where the numbers $a_i$ are uniquely defined up to permutation. Denote the elementary symmetric polynomials of the numbers $a_i$ by $\\sigma_1$, $\\ldots$, $\\sigma_{n-1}$. The talk will focus on some properties of the affine mapping

$$(c_1,\\ldots ,c_{n-1})\\mapsto (\\sigma_1,\\ldots ,\\sigma_{n-1})$$


16:30-18:00   数理科学研究科棟(駒場) 128号室
馬 昭平氏 氏 (東大数理)

[ 講演概要 ]



16:30-18:00   数理科学研究科棟(駒場) 056号室
Chris Heunen 氏 (Radboud Universiteit Nijmegen)
A topos for algebraic quantum theory



16:30-18:30   数理科学研究科棟(駒場) 056号室
Bruno Kahn 氏 (Paris第7大学)
On the classifying space of a linear algebraic group


15:30-17:00   数理科学研究科棟(駒場) 470号室
永幡幸生 氏 (阪大基礎工)



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
五味 清紀 氏 (京都大学大学院理学研究科)
A finite-dimensional construction of the Chern character for
twisted K-theory
[ 講演概要 ]
Twisted K-theory is a variant of topological K-theory, and
is attracting much interest due to applications to physics recently.
Usually, twisted K-theory is formulated infinite-dimensionally, and
hence known constructions of its Chern character are more or less
abstract. The aim of my talk is to explain a purely finite-dimensional
construction of the Chern character for twisted K-theory, which allows
us to compute examples concretely. The construction is based on
twisted version of Furuta's generalized vector bundle, and Quillen's
This is a joint work with Yuji Terashima.



10:30-12:00   数理科学研究科棟(駒場) 126号室
大沢健夫 氏 (名古屋大学)

Kavli IPMU Komaba Seminar

17:00-18:30   数理科学研究科棟(駒場) 002号室
Kiyonori Gomi 氏 (Kyoto University)
Multiplication in differential cohomology and cohomology operation
[ 講演概要 ]
The notion of differential cohomology refines generalized
cohomology theory so as to incorporate information of differential
forms. The differential version of the ordinary cohomology has been
known as the Cheeger-Simons cohomology or the smooth Deligne
cohomology, while the general case was introduced by Hopkins and
Singer around 2002.

The theme of my talk is the cohomology operation induced from the
squaring map in the differential ordinary cohomology and the
differential K-cohomology: I will relate these operations to the
Steenrod operation and the Adams operation. I will also explain the
roles that the squaring maps play in 5-dimensional Chern-Simons theory
for pairs of B-fields and Hamiltonian quantization of generalized
abelian gauge fields.

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