過去の記録 ~02/18本日 02/19 | 今後の予定 02/20~


11:40-12:30   数理科学研究科棟(駒場) 122号室
Wolfgang Koenig 氏 (Weierstrass Institute Berlin)
Eigenvalue order statistics and mass concentration in the parabolic Anderson model (ENGLISH)
[ 講演概要 ]
We consider the random Schr\\"odinger operator on the lattice with i.i.d. potential, which is double-exponentially distributed. In a large box, we look at the lowest eigenvalues, together with the location of the centering of the corresponding eigenfunction, and derive a Poisson process limit law, after suitable rescaling and shifting, towards an explicit Poisson point process. This is a strong form of Anderson localization at the bottom of the spectrum. Since the potential is unbounded, also the eigenvalues are, and it turns out that the gaps between them are much larger than of inverse volume order. We explain an application to concentration properties of the corresponding Cauchy problem, the parabolic Anderson model. In fact, it will turn out that the total mass of the solution comes from just one island, asymptotically for large times. This is joint work in progress with Marek Biskup (Los Angeles and Budweis).


14:00-14:50   数理科学研究科棟(駒場) 122号室
Roman Kotecky 氏 (Charles University Prague/University of Warwick)
Gradient Gibbs models with non-convex potentials (ENGLISH)
[ 講演概要 ]
A motivation for gradient Gibbs measures in the study of macroscopic elasticity and in proving the Cauchy-Born rule will be explained. Results concerning strict convexity of the free energy will be formulated and discussed. Based on joint works with S. Adams and S. Mueller and with S. Luckhaus.


15:00-15:50   数理科学研究科棟(駒場) 122号室
Stefano Olla 氏 (University Paris - Dauphine)
Einstein relation and linear response for random walks in random environment (ENGLISH)



18:30-19:30   数理科学研究科棟(駒場) 056号室
Gerd Faltings 氏 (Max Planck Institute for Mathematics, Bonn)
Nonabelian p-adic Hodge theory and Frobenius (ENGLISH)
[ 講演概要 ]
Some time ago, I constructed a relation between Higgs-bundles and p-adic etale sheaves, on curves over a p-adic field. This corresponds (say in the abelian case) to a Hodge-Tate picture. In the lecture I try to explain one way to introduce Frobenius into the theory. We do not get a complete theory but at least can treat p-adic sheaves close to trivial.




16:00-18:00   数理科学研究科棟(駒場) 122号室
Michel Cristofol 氏 (マルセイユ大学) 16:00-17:00
"Inverse problems associated with linear and non-linear parabolic systems " (ENGLISH)
[ 講演概要 ]
In this talk, I present several inverse reconstruction results for linear and non linear parabolic systems with different coupling terms : for linear systems with reaction-convection terms and for cooperative systems like Lotka Volterra systems with strong coupling terms. I will show different approaches to prove uniqueness of the coefficients via Carleman inequalities or via regularities properties of the solutions.
Guillaume Olive 氏 (マルセイユ大学) 17:00-18:00
"Hautus test for the approximate controllability of linear systems" (ENGLISH)
[ 講演概要 ]
We will introduce some generalization of the Hautus test to linear parabolic systems and give some applications to the distributed and boundary approximate controllability of such systems.



16:30-18:00   数理科学研究科棟(駒場) 002号室

保江かな子 氏 (宇宙航空研究開発機構)
高次精度流体解析法の開発および航空宇宙分野への適用 (JAPANESE)
[ 講演概要 ]
現在,数値流体力学(CFD: Computational Fluid Dynamics)は様々な分野で用いられており,対象となる物体形状や流れ場はより複雑になってきている.特に航空宇宙分野では,航空機全機周りのよう に乱流が支配的となる流れ場が対象であるため,より高精度な解析手法が必要とされている.講演者らはこれまでに,複雑形状周りの流れ場であっ ても精度良く空力解析を実施することができるDiscontinuous Galerkin(DG)法に基づく非構造CFDソルバーの開発を行ってきた.本講演では,開発したセル緩和型陰的DG法の概要を説明し,計算例を紹介す る.また,航空宇宙分野におけるCFDと風洞試験との関わりについて簡単に紹介しながら,開発した手法の航空宇宙分野における実用問題への適 用例を示す.
[ 講演参考URL ]



15:30-17:00   数理科学研究科棟(駒場) 122号室
那須 弘和 氏 (東海大学理学部情報数理学科)
Obstructions to deforming curves on a uniruled 3-fold (JAPANESE)
[ 講演概要 ]
In this talk, I review some results from a joint work with Mukai:
1. a generalization of Mumford's example of a non-reduced component of the Hilbert scheme, and
2. a sufficient condition for a first order deformation of a curve on a uniruled 3-fold to be obstructed.
As a sequel of the study, we will discuss some obstructed deformations of degenerate curves on a higher dimensional scroll.



16:30-18:00   数理科学研究科棟(駒場) 117号室
Spyridon Michalakis 氏 (Caltech)
Stability of topological phases of matter (ENGLISH)


16:30-18:00   数理科学研究科棟(駒場) 002号室
Dmitry Kaledin 氏 (Steklov Mathematics Institute/ KIAS)
Cyclic K-theory (ENGLISH)
[ 講演概要 ]
Cyclic K-theory is a variant of algebraic K-theory introduced by Goodwillie 25 years ago and more-or-less forgotten by now. I will try to convince the audience that cyclic K-theory is actually quite useful -- in particular, it can be effectively computed for varieties over a finite field.



15:00-16:10   数理科学研究科棟(駒場) 002号室
広瀬 勇一 氏 (Victoria University of Wellington)
Information criteria for parametric and semi-parametric models (JAPANESE)
[ 講演概要 ]
Since Akaike proposed an Information Criteria, this approach to
model selection has been important part of Statistical data analysis.
Since then many Information Criteria have been proposed and it is still
an active field of research. Despite there are many contributors in this
topic, we have not have proper Information Criteria for semiparametric
models. In this talk, we give ideas to develop an Information Criteria
for semiparametric models.
[ 講演参考URL ]



16:30-18:00   数理科学研究科棟(駒場) 126号室
Spyridon Michalakis 氏 (Caltech)
Stability of topological phases of matter (ENGLISH)


17:00-18:00   数理科学研究科棟(駒場) 056号室
Tea: 16:40 - 17:00 コモンルーム
Athanase Papadopoulos 氏 (IRMA, Univ. de Strasbourg)
Mapping class group actions (ENGLISH)
[ 講演概要 ]
I will describe and present some rigidity results on mapping
class group actions on spaces of foliations on surfaces, equipped with various topologies.


16:30-18:00   数理科学研究科棟(駒場) 002号室
Daniel Sternheimer 氏 (Rikkyo Univertiry and Université de Bourgogne)
Symmetries, (their) deformations, and physics: some perspectives and open problems from half a century of personal experience (ENGLISH)
[ 講演概要 ]
This is a flexible general framework, based on quite a number of papers, some of which are reviewed in:
MR2285047 (2008c:53079) Sternheimer, Daniel. The geometry of space-time and its deformations from a physical perspective. From geometry to quantum mechanics, 287–301, Progr. Math., 252, Birkhäuser Boston, Boston, MA, 2007



15:30-17:00   数理科学研究科棟(駒場) 122号室
川谷康太郎 氏 (京都大学大学院理学研究科)
Comparison with Gieseker stability and slope stability via Bridgeland's stability (JAPANESE)
[ 講演概要 ]
In this talk we compare two classical notions of stability (Gieseker stability and slope stability) for sheaves on K3 surfaces by using stability conditions which was introduced by Bridgeland. As a consequence of this work, we give a classification of 2 dimensional moduli spaces of sheaves on K3 surface depending on the rank of the sheaves.


10:30-12:00   数理科学研究科棟(駒場) 128号室
松村慎一 氏 (東大数理)
An ampleness criterion with the extendability of singular positive metrics (JAPANESE)
[ 講演概要 ]
Coman, Guedj and Zeriahi proved that, for an ample line bundle $L$ on a projective manifold $X$, any singular positive metric on the line bundle $L|_{V}$ along a subvariety $V \subset X$ can be extended to a global singular positive metric of $L$. In this talk, we prove that the extendability of singular positive metrics on a line bundle along a subvariety implies the ampleness of the line bundle.



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)。

下村 明洋 氏 (東京大学・大学院数理科学研究科)
非線型分散型発展方程式について (JAPANESE)
[ 講演概要 ]



16:30-18:00   数理科学研究科棟(駒場) 117号室
Spyridon Michalakis 氏 (Caltech)
Stability of topological phases of matter (ENGLISH)



16:30-18:00   数理科学研究科棟(駒場) 126号室

Spyridon Michalakis 氏
( Institute for Quantum Information and Matter (Caltech))
Stability of topological phases of matter (ENGLISH)
[ 講演概要 ]
The first lecture will be an introduction to quantum mechanics and a proof of Lieb-Robinson bounds for constant range interaction Hamiltonians. The second lecture will build on the first to prove a powerful lemma on the transformation of the interactions of generic gapped Hamiltonians to a new set of rapidly-decaying interactions that commute with the groundstate subspace. I call this "The Energy Filtering Lemma". Then, the third lecture will be on the construction of the Spectral Flow unitary (Quasi-adiabatic evolution) and its properties; in particular, the perfect simulation of the evolution of the groundstate subspace within a gapped path. I will end with a presentation of the recent result on the stability of the spectral gap for frustration-free Hamiltonians, highlighting how the previous three lectures fit into the proof.


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
河野俊丈 氏 (東京大学大学院数理科学研究科)
Quantum and homological representations of braid groups (JAPANESE)
[ 講演概要 ]
Homological representations of braid groups are defined as
the action of homeomorphisms of a punctured disk on
the homology of an abelian covering of its configuration space.
These representations were extensively studied by Lawrence,
Krammer and Bigelow. In this talk we show that specializations
of the homological representations of braid groups
are equivalent to the monodromy of the KZ equation with
values in the space of null vectors in the tensor product
of Verma modules when the parameters are generic.
To prove this we use representations of the solutions of the
KZ equation by hypergeometric integrals due to Schechtman,
Varchenko and others.

In the case of special parameters these representations
are extended to quantum representations of mapping
class groups. We describe the images of such representations
and show that the images of any Johnson subgroups
contain non-abelian free groups if the genus and the
level are sufficiently large. The last part is a joint
work with Louis Funar.


16:30-18:00   数理科学研究科棟(駒場) 002号室
奥田隆幸 氏 (Graduate School of Mathematical Sciences, the University of Tokyo)
Smallest complex nilpotent orbit with real points (JAPANESE)
[ 講演概要 ]
Let $\\mathfrak{g}$ be a non-compact simple Lie algebra with no complex
In this talk, we show that there exists a complex nilpotent orbit
$\\mathcal{O}^{G_\\mathbb{C}}_{\\text{min},\\mathfrak{g}}$ in
$\\mathfrak{g}_\\mathbb{C}$ ($:=\\mathfrak{g} \\otimes \\mathbb{C}$)
containing all of real nilpotent orbits in $\\mathfrak{g}$ of minimal
positive dimension.
For many $\\mathfrak{g}$, the orbit
$\\mathcal{O}^{G_\\mathbb{C}}_{\\text{min},\\mathfrak{g}}$ is just the
complex minimal nilpotent orbit in $\\mathfrak{g}_\\mathbb{C}$.
However, for the cases where $\\mathfrak{g}$ is isomorphic to
$\\mathfrak{su}^*(2k)$, $\\mathfrak{so}(n-1,1)$, $\\mathfrak{sp}(p,q)$,
$\\mathfrak{e}_{6(-26)}$ or $\\mathfrak{f}_{4(-20)}$,
the orbit $\\mathcal{O}^{G_\\mathbb{C}}_{\\text{min},\\mathfrak{g}}$ is not
the complex minimal nilpotent orbit in $\\mathfrak{g}_\\mathbb{C}$.
We also determine $\\mathcal{O}^{G_\\mathbb{C}}_{\\text{min},\\mathfrak{g}}$
by describing the weighted Dynkin diagrams of these for such cases.



10:30-12:00   数理科学研究科棟(駒場) 128号室
糟谷久矢 氏 (東大数理)
Techniques of computations of Dolbeault cohomology of solvmanifolds (JAPANESE)


13:30-14:30   数理科学研究科棟(駒場) 056号室
Ernie Esser 氏 (University of California, Irvine)
A convex model for non-negative matrix factorization and dimensionality reduction on physical space (ENGLISH)
[ 講演概要 ]
A collaborative convex framework for factoring a data matrix X into a non-negative product AS, with a sparse coefficient matrix S, is proposed. We restrict the columns of the dictionary matrix A to coincide with certain columns of the data matrix X, thereby guaranteeing a physically meaningful dictionary and dimensionality reduction. We focus on applications of the proposed framework to hyperspectral endmember and abundances identification and also show an application to blind source separation of NMR data.
This talk is based on joint work with Michael Moeller, Stanley Osher, Guillermo Sapiro and Jack Xin.

Kavli IPMU Komaba Seminar

16:30-18:00   数理科学研究科棟(駒場) 002号室
Siu-Cheong Lau 氏 (IPMU)
Enuemerative meaning of mirror maps for toric Calabi-Yau manifolds (ENGLISH)
[ 講演概要 ]
For a mirror pair of smooth manifolds X and Y, mirror symmetry associates a complex structure on Y to each Kaehler structure on X, and this association is called the mirror map. Traditionally mirror maps are defined by solving Picard-Fuchs equations and its geometric meaning was unclear. In this talk I explain a recent joint work with K.W. Chan, N.C. Leung and H.H. Tseng which proves that mirror maps can be obtained by taking torus duality (the SYZ approach) and disk-counting for a class of toric Calabi-Yau manifolds in any dimensions. As a consequence we can compute disk-counting invariants by solving Picard-Fuchs equations.



10:15-12:30   数理科学研究科棟(駒場) 117号室
関口次郎 氏 (東京農工大学) 10:15-11:15
二面体群に関連する超楕円積分 (JAPANESE)
[ 講演概要 ]
大西良博 氏 (山梨大学) 11:30-12:30
高い種数の代数関数体に対する、一般化された Bernoulli-Hurwitz 数と、関連する諸問題(概説) (JAPANESE)
[ 講演概要 ]
種数の高いある種の代数曲線に付随した代数函数 (楕円函数の自然な一般化) の Laurent 展開係数である generalized Bernoulli-Hurwitz 数が Bernoulli 数やBernoulli-Hurwitz 数と強く類似した性質 (Clausen von Staudt, von Staudt 第 2, Kummer 自身の得た合同式) を持つことについて survey をし, 最後に, その先にある問題について言及する.



15:00-16:00   数理科学研究科棟(駒場) 052号室
磯崎 洋 氏 (筑波大学)
Inverse problems for heat equations with discontinuous conductivities
[ 講演概要 ]
In a bounded domain $\\Omega \\subset {\\bf R}^n$, consider the heat
equation $\\partial_tu = \\nabla(\\gamma(t,x)\\nabla u)$. The heat
conductivity is assumed to be piecewise constant : $\\gamma = k^2$ on
$\\Omaga_1(t) \\subset\\subset \\Omega$, $\\gamma(t,x) = 1$ on
$\\Omega\\setminus\\Omega_1(t)$. In this talk, we present recent results
for the inverse problems of reconstructing $\\gamma(t,x)$ from the
Dirichlet-to-Neumann map :
$u(t)|_{\\partial\\Omega} \\to $\\partial_{\\nu}u|_{\\partial\\Omega}$ for a time
interval $(0,T)$. These are the joint works with P.Gaitan, O.Poisson,
S.Siltanen, J.Tamminen.

< 前へ 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143 次へ >