過去の記録 ~10/04本日 10/05 | 今後の予定 10/06~


17:00-18:00   数理科学研究科棟(駒場) 470号室
Oleg Emanouilov 氏 (Colorado State Univ.)
Inverse problem for the Maxwell equations (ENGLISH)
[ 講演概要 ]
We consider an analog of Caderon's problem for the system of Maxwell equations in a cylindrical domain.
Under some geometrical assumptions on domain we show that from the partial data one can recover the complete set of parameters.



13:30-14:40   数理科学研究科棟(駒場) 052号室
竹内 敦司 氏 (大阪市立大学)
Density of solutions to stochastic functional differential equations (JAPANESE)
[ 講演概要 ]
過去の履歴に依存した確率微分方程式(確率関数微分方程式)を考える. その解として定まる確率過程は非マルコフ過程であり,さまざまな解析的 手法を適用することが極めて困難である.マリアヴァン解析を用いることに より,拡散係数の一様非退化性から,解の分布が滑らかな密度関数を 持つことが分かる.本講演では,解過程に関する大偏差原理を紹介し, マリアヴァン解析を合わせることにより,密度関数の漸近評価が得られる ことを述べる.
[ 参考URL ]



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
徳永 浩雄 氏 (首都大学東京)
有理楕円曲面とあるline-conic arrangements (JAPANESE)
[ 講演概要 ]


10:30-11:30   数理科学研究科棟(駒場) 056号室
Huaxiong Huang 氏 (York University)
An immersed boundary method for mass transfer across permeable moving interfaces (ENGLISH)
[ 講演概要 ]
In this talk, we present an immersed boundary method for mass transfer across permeable deformable moving interfaces interacting with the surrounding fluids. One of the key features of our method is the introduction of the mass flux as an independent variable, governed by a non-standard vector transport equation. The flux equation, coupled with the mass transport and the fluid flow equations, allows for a natural implementation of an immersed boundary algorithm when the flux across the interfaces is proportional to the jump in concentration. As an example, the oxygen transfer from red blood cells in a capillary to its wall is used to illustrate the applicability of the proposed method. We show that our method is capable of handling multi-physics problems involving fluid- structure interaction with multiple deformable moving interfaces and (interfacial) mass transfer simultaneously.
This is joint work with X. Gong and Z. Gong.


16:30-18:00   数理科学研究科棟(駒場) 128号室
水谷 治哉 氏 (学習院大学)
Global Strichartz estimates for Schr\\"odinger equations with long range metrics (JAPANESE)
[ 講演概要 ]
We consider Schr\\"odinger equations on the asymptotically Euclidean space
with the long-range condition on the metric.
We show that if the high energy resolvent has at most polynomial growth with respect to the energy,
then global-in-time Strichartz estimates, outside a large compact set, hold.
Under the non-trapping condition we also discuss global-in-space Strichartz estimates.
This talk is based on a joint work with J.-M. Bouclet (Toulouse University).



10:30-12:00   数理科学研究科棟(駒場) 126号室
服部 広大 氏 (東大数理)
On hyperkaehler metrics on holomorphic cotangent bundles on complex reductive Lie groups (JAPANESE)
[ 講演概要 ]
There exists a complete hyperkaehler metric on the holomorphic cotangent bundle on each complex reductive Lie group. It was constructed by Kronheimer, using hyperkaehler quotient method. In this talk I explain how to describe the Kaehler potentials of these metrics.


15:30-17:00   数理科学研究科棟(駒場) 122号室
小池 貴之 氏 (東大数理)
Minimal singular metrics of some line bundles with infinitely generated section rings (JAPANESE)
[ 講演概要 ]
We consider Hermitian metrics of pseudo-effective line bundles on smooth
projective varieties defined over $\\mathbb{C}$.
Especially we are interested in (possibly singular) Hermitian metrics
with semi-positive curvatures when the section rings are not finitely generated.
We study where and how minimal singular metrics, special Hermitian
metrics with semi-positive curvatures, diverges in the following two situations;
a line bundle admitting no Zariski decomposition even after any
modifications (Nakayama example)
and a nef line bundle $L$ on $X$ satisfying $D \\subset |mL|$ and $|mL-D|
= \\emptyset$ for some divisor $D \\subset X$ and for all $m \\geq 1$ (
Zariski example).



10:40-11:40   数理科学研究科棟(駒場) 123号室
Alfred RAMANI 氏 (École polytechnique)
Integrable discrete systems, an introduction Pt. 2 (ENGLISH)
[ 講演概要 ]
The second part will mostly be devoted to the various integrability detectors (singularity confinement, algebraic entropy) for integrability of discrete systems, in one or more dimensions. The most important systems identified through these detectors, namely the discrete Painlev¥'e equations, will be presented in detail, through a geometric approach.



15:30-17:00   数理科学研究科棟(駒場) 056号室
この講義はMini workshop on birational geometryの一環として行われます
Florin Ambro 氏 (IMAR)
Cyclic covers and toroidal embeddings (ENGLISH)
[ 参考URL ]



16:40-17:40   数理科学研究科棟(駒場) 056号室
Valentina Di Proietto 氏 (東京大学数理科学研究科)
On the homotopy exact sequence for the logarithmic de Rham fundamental group (ENGLISH)
[ 講演概要 ]
Let K be a field of characteristic 0 and let X* be a quasi-projective simple normal crossing log variety over the log point K* associated to K. We construct a log de Rham version of the homotopy sequence \\pi_1(X*/K*)-->\\pi_1(X*/K)--\\pi_1(K*/K)-->1 and prove that it is exact. Moreover we show the injectivity of the first map for certain quotients of the groups. Our proofs are purely algebraic. This is a joint work with A. Shiho.


16:30-18:00   数理科学研究科棟(駒場) 118号室
Camille Male 氏 (Univ. Paris VII)
The spectrum of large random matrices, the non commutative random variables and the distribution of traffics (ENGLISH)


13:30-14:40   数理科学研究科棟(駒場) 052号室
野村 亮介 氏 (東京大学大学院数理科学研究科)
TD法における価値関数への収束アルゴリズム (JAPANESE)
[ 講演概要 ]
マルコフ過程に従い状態遷移が行われ、状態に応じた報酬が支 払われるモデルにおいて、その報酬の累積和の期待値、価値関数を推定する問題 を考える。線形関数近似を用いたTD法において、真の価値関数が特徴量の線形結 合で表されない場合であっても収束することは知られているが、特徴量の選択に よって性能に大きな差が出てしまう。そこで、得られた極限を真の価値関数へ補 正するように特徴量を構成することによって、真の価値関数に収束するアルゴリ ズムを提案し、その効率を上げる手法について説明する。
[ 参考URL ]



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
児玉 大樹 氏 (東京大学大学院数理科学研究科)
測度論的基本領域を持つ円周上の極小微分同相写像 (JAPANESE)
[ 講演概要 ]


16:30-18:00   数理科学研究科棟(駒場) 128号室
Alexander Pushnitski 氏 (King's Colledge London)
Inverse spectral problem for positive Hankel operators (ENGLISH)
[ 講演概要 ]
Hankel operators are given by (infinite) matrices with entries
$a_{n+m}$ in $\\ell^2$. We consider inverse spectral problem
for bounded self-adjoint positive Hankel operators.
A famous theorem due to Megretskii, Peller and Treil asserts
that such operators may have any continuous spectrum of
multiplicity one or two and any set of eigenvalues of multiplicity
one. However, more detailed questions of inverse spectral
problem, such as the description of isospectral sets, have never
been addressed. In this talk I will describe in detail the
direct and inverse spectral problem for a particular sub-class
of positive Hankel operators. The talk is based on joint work
with Patrick Gerard (Paris, Orsay).


16:30-17:30   数理科学研究科棟(駒場) 126号室
Simon Gindikin 氏 (Rutgers University (USA))
Horospheres, wonderfull compactification and c-function (JAPANESE)
[ 講演概要 ]
I will discuss what is closures of horospheres at the wonderfull compactification and how does it connected with horospherical transforms, c-functions and product-formulas



10:30-12:00   数理科学研究科棟(駒場) 126号室
藤川 英華 氏 (千葉大学)
無限型リーマン面に対する安定写像類群とモジュライ空間 (JAPANESE)
[ 講演概要 ]
近年の無限次元タイヒミュラー空間論の進展について, タイヒミュラーモジュラー群の作用の話題を中心として解説する. 特に, 安定写像類群の軌道の様相と漸近的タイヒミュラー空間への作用の関連を述べ, 一般化された固定点定理とニールセン実現定理を紹介する. またモジュライ空間の構造の考察へのアプローチを述べる.


15:30-16:30   数理科学研究科棟(駒場) 056号室
Alfred RAMANI 氏 (École polytechnique)
Integrable discrete systems, an introduction Pt.1 (ENGLISH)
[ 講演概要 ]
The first part will contain a general overview of the notion of integrability, starting from continuous systems with or without physical applications. The Painlev¥'e property will be discussed as an integrability detector for integrability of continuous systems. The notion of integrability of discrete systems will be introduced next. One dimensional systems will be presented as well as multidimensional ones.

Kavli IPMU Komaba Seminar

17:00-18:30   数理科学研究科棟(駒場) 002号室
Mauricio Romo 氏 (Kavli IPMU)
Exact Results In Two-Dimensional (2,2) Supersymmetric Gauge Theories With Boundary
[ 講演概要 ]
I will talk about the recent computation, done in joint work with Prof. K. Hori, of the partition function on the hemisphere of a class of two-dimensional (2,2) supersymmetric field theories including gauged linear sigma models (GLSM). The result provides a general exact formula for the central charge of the D-branes placed at the boundary. From the mathematical point of view, for the case of GLSMs that admit a geometrical interpretation, this formula provides an expression for the central charge of objects in the derived category at any point of the stringy Kahler moduli space. I will describe how this formula arises from physics and give simple, yet important, examples that supports its validity. If time allows, I will also explain some of its consequences such as how it can be used to obtain the grade restriction rule for branes near phase boundaries.


15:30-17:00   数理科学研究科棟(駒場) 122号室
Florin Ambro 氏 (IMAR)
An injectivity theorem (ENGLISH)
[ 講演概要 ]
I will discuss a generalization of the injectivity theorem of Esnault-Viehweg, and an
application to the problem of lifting sections from the non-log canonical locus of a log variety.



13:30-16:00   数理科学研究科棟(駒場) 123号室
宗野 惠樹 氏 (東京農工大学) 13:30-14:30
Pair correlation of low lying zeros of quadratic L-functions (JAPANESE)
[ 講演概要 ]
In this talk, we give certain asymptotic formula involving non-trivial zeros of L-functions associated to Knonecker symbol under the assumption of the Generalized Riemann Hypothesis. From this formula, we obtain several results on non-trivial zeros of quadratic L-functions near the real axis.
松谷茂樹 氏 (相模原 在住) 15:30-16:00
σ関数と空間曲線 (JAPANESE)
[ 講演概要 ]
In this talk, I show that Kleinian sigma function, which is a generalization of Weierstrass elliptic sigma function, is extended to space curves, (3,4,5), (3,7,8) and (6,13,14,15,16) type. In terms of the function, the Jacob inversion formula is also generalized, in which the affine coordinates are given as functions of strata of Jacobi variety associated with these curves.


13:00-18:00   数理科学研究科棟(駒場) 128号室
胡 国栄 氏 (東京大学) 13:30-15:00
Besov and Triebel-Lizorkin spaces associated with
non-negative self-adjoint operators
[ 講演概要 ]
Let $(X,d)$ be a locally compact metric space
endowed with a doubling measure $¥mu$, and
let $L$ be a non-negative self-adjoint operator on $L^{2}(X,d¥mu)$.
Assume that the semigroup
generated by $L$ consists of integral operators with (heat) kernel
enjoying Gaussian upper bound but having no information on the
regularity in the variables $x$ and $y$.
In this talk, we shall introduce Besov and Triebel-Lizorkin spaces associated
with $L$, and
present an atomic decomposition of these function spaces.
佐々木 浩宣 氏 (千葉大学) 15:30-17:00
空間1次元非線型Dirac方程式に於ける解の漸近挙動について (JAPANESE)
[ 講演概要 ]



10:00-11:30   数理科学研究科棟(駒場) 122号室
開始時間と開催場所などは変更されることがあるので, セミナーごとにご確認ください.
梶浦宏成 氏 (千葉大学)
トーラスファイバー束のホモロジー的ミラー対称性とその変形 (JAPANESE)
[ 講演概要 ]
Strominger-Yau-Zaslow によるトーラスファイバー束によるミラー対称性の定式化のある変形として, ある葉層構造を持つシンプレクティックトーラスファイバー束と複素トーラスファイバー束のある非可換変形の組を考える. この変形の組がミラー双対であると主張するための根拠として, 両者の間のホモロジー的ミラー対称性を考える. つまり, シンプレクティックトーラスファイバー束上の深谷圏と複素トーラスファイバー束上の連接層の導来圏の変形を考え, その2つの圏の同値性について議論する. (変形していない状況で分かっているレベルで, その変形した設定でも成り立つことがいえる. )


16:00-17:30   数理科学研究科棟(駒場) 002号室
Danielle Hilhorst 氏 (Université de Paris-Sud / CNRS)
Singular limit of a damped wave equation with a bistable nonlinearity (ENGLISH)
[ 講演概要 ]
We study the singular limit of a damped wave equation with
a bistable nonlinearity. In order to understand interfacial
phenomena, we derive estimates for the generation and the motion
of interfaces. We prove that steep interfaces are generated in
a short time and that their motion is governed by mean curvature
flow under the assumption that the damping is sufficiently strong.
To this purpose, we prove a comparison principle for the damped
wave equation and construct suitable sub- and super-solutions.

This is joint work with Mitsunori Nata.



10:30-11:30   数理科学研究科棟(駒場) 056号室
Mark Wilkinson 氏 (École normale supérieure - Paris)
Eigenvalue Constraints and Regularity of Q-tensor Navier-Stokes Dynamics (ENGLISH)
[ 講演概要 ]
The Q-tensor is a traceless and symmetric 3x3 matrix that describes the small-scale structure in nematic liquid crystals. In order to be physically meaningful, its eigenvalues should be bounded below by -1/3 and above by 2/3. This constraint raises questions regarding the physical predictions of theories which employ the Q-tensor; it also raises analytical issues in both static and dynamic Q-tensor theories of nematic liquid crystals. John Ball and Apala Majumdar recently constructed a singular map on traceless, symmetric matrices that penalises unphysical Q-tensors by giving them an infinite energy cost. In this talk, I shall present some mathematical results for a coupled Navier-Stokes system modelling nematic dynamics into which this map is built, including the existence, regularity and so-called `strict physicality' of its weak solutions.


18:00-19:00   数理科学研究科棟(駒場) 056号室
Yichao Tian 氏 (Morningside Center for Mathematics)
Goren-Oort stratification and Tate cycles on Hilbert modular varieties (ENGLISH)
[ 講演概要 ]
Let B be a quaternionic algebra over a totally real field F, and p be a prime at least 3 unramified in F. We consider a Shimura variety X associated to B^* of level prime to p. A generalization of Deligne-Carayol's "modèle étrange" allows us to define an integral model for X. We will then define a Goren-Oort stratification on the characteristic p fiber of X, and show that each closed Goren-Oort stratum is an iterated P^1-fibration over another quaternionic Shimura variety in characteristic p. Now suppose that [F:Q] is even and that p is inert in F. An iteration of this construction gives rise to many algebraic cycles of middle codimension on the characteristic p fibre of Hilbert modular varieties of prime-to-p level. We show that the cohomological classes of these cycles generate a large subspace of the Tate cycles, which, in some special cases, coincides with the prediction of the Tate conjecture for the Hilbert modular variety over finite fields. This is a joint work with Liang Xiao.
(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.)

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