過去の記録

過去の記録 ~02/23本日 02/24 | 今後の予定 02/25~

2013年01月07日(月)

GCOEレクチャーズ

16:30-17:30   数理科学研究科棟(駒場) 118号室
Kazufumi Ito 氏 (North Carolina State Univ.)
Traffic flow modeling and Hamilton Jacobi equation (ENGLISH)
[ 講演概要 ]
A traffic model based on Hamilton Jacobi equations are developed. The model incorporates the sag and source conditions of traffic flows and predict and classify the traffic congestion.

2012年12月26日(水)

作用素環セミナー

15:45-18:00   数理科学研究科棟(駒場) 118号室
Henrik Densing Petersen 氏 (Univ. Copenhagen) 15:45-16:45
Trouble in paradise (ENGLISH)
Stella Anevski 氏 (Univ. Copenhagen) 17:00-18:00
Algebraic K-theory of generalized schemes (ENGLISH)

2012年12月21日(金)

GCOEレクチャーズ

15:00-16:00   数理科学研究科棟(駒場) 126号室
Kazufumi Ito 氏 (North Carolina State Univ.)
Evolution equation approach to Fractional Differential Equations (ENGLISH)
[ 講演概要 ]
A class of fractional differential equations is formulated as an evolution equation on the memory space with non-local boundary condition. Based on such a formulation the mathematical theory of evolution equations is applied to concrete examples of nonlinear fractional PDEs.

2012年12月19日(水)

作用素環セミナー

15:45-18:00   数理科学研究科棟(駒場) 118号室
Mihaita Berbec 氏 (KU Leuven) 15:45-16:45
$W^*$-superrigidity for left-right wreath products (ENGLISH)
Zhuang Niu 氏 (Univ. Wyoming) 17:00-18:00
A classification of approximate subhomogeneous $C^*$-algebras (ENGLISH)

幾何コロキウム

10:30-12:00   数理科学研究科棟(駒場) 128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.
藤原 耕二 氏 (京都大学)
ベイユ・ピーターソン空間上のファンク距離 (JAPANESE)
[ 講演概要 ]
タイヒミュラー空間上のベイユ・ピーターソン距離に関するファンク関数について論じる。ファンク関数は、写像類群で不変な非対称距離になる。元々は、ユークリッド空間の凸領域に対してファンクが定義した概念で、その対称化はヒルベルト距離である。

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
中村 健太郎 氏 (北海道大学)
A generalization of Kato's local epsilon conjecture for
(φ, Γ)-modules over the Robba ring (JAPANESE)
[ 講演概要 ]
In his preprint “Lectures on the approach to Iwasawa theory of Hasse-Weil L-functions via B_dR, Part II ", Kazuya Kato proposed a conjecture called local epsilon conjecture. This conjecture predicts that the determinant of the Galois cohomology of a family of p-adic Galois representations has a canonical base whose specializations at de Rham points can be characterized by using Bloch-Kato exponential, L-factors and Deligne-Langlands epsilon constants of the associated Weil-Deligne representations.
In my talk, I generalize his conjecture for families of (φ, Γ)-modules over the Robba ring, and prove a part of this conjecture in the trianguline case. The two key ingredients are the recent result of Kedlaya-Pottharst-Xiao on the finiteness of cohomologies of (φ, Γ)-modules and my result on Bloch-Kato exponential map for (φ, Γ)-modules.

GCOEセミナー

15:45-16:45   数理科学研究科棟(駒場) 118号室
Mihaita Berbec 氏 (KU Leuven)
$W^*$-superrigidity for left-right wreath products (ENGLISH)

2012年12月18日(火)

FMSPレクチャーズ

10:30-11:30   数理科学研究科棟(駒場) 056号室
Jie Jiang 氏 (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences)
On convergence to equilibrium with applications of Lojasiewicz-Simon
inequality (II) (ENGLISH)

2012年12月17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
生駒 英晃 氏 (京都大学)
算術多様体上のノルムの小さい基底の存在について
(JAPANESE)
[ 講演概要 ]
I would like to talk about some recent work of mine on the asymptotic behavior of the successive minima associated to a graded arithmetic linear series. A complete arithmetic linear series belonging to a hermitian line bundle on an arithmetic variety is defined as the Z-module of the global sections endowed with the supremum-norm, and the successive minima are invariants that measure the size of the sections with small norms.
If time permits, I would like to also explain some close relationship between the results and the general equi-distribution theory of rational points on an arithmetic variety.

2012年12月15日(土)

東京無限可積分系セミナー

13:30-15:00   数理科学研究科棟(駒場) 117号室
Vincent Pasquier 氏 (CEA, Saclay, France)
current and integrability (ENGLISH)
[ 講演概要 ]
I will describe some problems related to currents in XXZ chains:
Drude conductivity, Linbladt equation, tasep, matrix ansatz,
in particular the relation of permanent currents with integrability.
If time permits I will also discuss a nonrelated subject:
deformation of fusion rules in minimal models and Macdonald polynomials.

2012年12月13日(木)

代数幾何学セミナー

10:40-12:10   数理科学研究科棟(駒場) 118号室
いつもと曜日・時間・場所が異なります
Jean-Paul Brasselet 氏 (CNRS (Luminy))
The asymptotic variety of polynomial maps (ENGLISH)
[ 講演概要 ]
The asymptotic variety, or set of non-properness has been intensively studied by Zbigniew Jelonek. In a recent paper, Anna and Guillaume Valette associate to a polynomial map $F: {\\mathbb C}^n \\to {\\mathbb C}^n$ a singular variety $N_F$ and relate properness property of $F$ to the vanishing of some intersection homology groups of $N_F$. I will explain how stratifications of the asymptotic variety of $F$ play an important role in the story and how recently, one of my students, Nguyen Thi Bich Thuy, found a nice way to exhibit such a suitable stratification.

2012年12月12日(水)

代数学コロキウム

18:00-19:00   数理科学研究科棟(駒場) 002号室
François Charles 氏 (CNRS & Université de Rennes 1)
The Tate conjecture for K3 surfaces and holomorphic symplectic varieties over finite fields (ENGLISH)
[ 講演概要 ]
We prove the Tate conjecture for divisors on reductions of holomorphic symplectic varieties over finite fields -- with some restrictions on the characteristic of the base field. We will be concerned mostly with the supersingular case. As a special case, we prove the Tate conjecture, also known as Artin's conjecture in our case, for K3 surfaces over finite fields of characteristic at least 5 and for codimension 2 cycles on cubic fourfolds.

(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.)

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
N. Christopher Phillips 氏 (Univ. Oregon)
Large subalgebras of crossed product $C^*$-algebras (ENGLISH)

FMSPレクチャーズ

16:30-18:00   数理科学研究科棟(駒場) 118号室
N. Christopher Phillips 氏 (Univ. Oregon)
Large subalgebras of crossed product C*-algebras (ENGLISH)
[ 講演概要 ]
This is work in progress; not everything has been checked.
We define a "large subalgebra" and a "centrally large subalgebra" of a C*-algebra. The motivating example is what we now call the "orbit breaking subalgebra" of the crossed product by a minimal homeomorphism h of a compact metric space X. Let v be the standard unitary in the crossed product C* (Z, X, h). For a closed subset Y of X, we form the subalgebra of C* (Z, X, h) generated by C (X) and all elements f v for f in C (X) such that f vanishes on Y. When each orbit meets Y at most once, this subalgebra is centrally large in the crossed product. Crossed products by smooth free minimal actions of Zd also contain centrally large subalgebras which are simple direct limits, with no dimension growth, of recursive subhomogeneous algebras.
If B is a large subalgebra of A, then the Cuntz semigroups of A and B are the almost the same: if one deletes the classes of nonzero projections, then the inclusion is a bijection on what is left. Also (joint work with Dawn Archey), if B is a centrally large subalgebra of A, and B has stable rank one, then so does A. Moreover, if B is a centrally large subalgebra of A, if B is Z-stable, and if A is nuclear, then A is Z-stable.

2012年12月11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
Ismar Volic 氏 (Wellesley College)
Homotopy-theoretic methods in the study of spaces of knots and links (ENGLISH)
[ 講演概要 ]
I will survey the ways in which some homotopy-theoretic
methods, manifold calculus of functors main among them, have in recent
years been used for extracting information about the topology of
spaces of knots and links. Cosimplicial spaces and operads will also
be featured. I will end with some recent results about spaces of
homotopy string links and in particular about how one can use functor
calculus in combination with configuration space integrals to extract
information about Milnor invariants.

解析学火曜セミナー

16:30-18:00   数理科学研究科棟(駒場) 128号室
講演中止になりました.
Rafe Mazzeo 氏 (Stanford University)
This talk was cancelled! (JAPANESE)

FMSPレクチャーズ

10:30-11:30   数理科学研究科棟(駒場) 056号室
Jie Jiang 氏 (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences)
On convergence to equilibrium with applications of Lojasiewicz-Simon
inequality (I) (ENGLISH)

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
疋田辰之 氏 (京都大学大学院理学研究科)
Affine Springer fibers of type A and combinatorics of diagonal
coinvariants
Affine Springer fibers of type A and combinatorics of diagonal
coinvariants (JAPANESE)
[ 講演概要 ]
We introduce certain filtrations on the homology of
affine Springer fibers of type A and give combinatorial formulas for the bigraded Frobenius series of the associated graded modules.
The results are essentially given by generalizations of the symmetric function introduced by Haglund, Haiman, Loehr, Remmel, and Ulyanov which is conjectured to coincide with the bigraded Frobenius series of the ring of diagonal coinvariants.

2012年12月10日(月)

代数幾何学セミナー

15:30-17:00   数理科学研究科棟(駒場) 122号室
川谷 康太郎 氏 (名古屋大学多元数理科学研究科)
A hyperbolic metric and stability conditions on K3 surfaces with $¥rho=1$ (JAPANESE)
[ 講演概要 ]
We introduce a hyperbolic metric on the (normalized) space of stability conditions on projective K3 surfaces $X$ with Picard rank 1. Furthermore we demonstrate how this hyperbolic metric is helpful for us by discussing two or three topics.

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
金子 宏 氏 (東京理科大)
A Dirichlet space on ends of tree and Dirichlet forms with a nodewise orthogonal property (JAPANESE)

2012年12月07日(金)

統計数学セミナー

14:50-16:00   数理科学研究科棟(駒場) 006号室
参加をご希望される方は鎌谷 (阪大基礎工); kamatani at sigmath.es.osaka-u.ac.jpまでご連絡ください.
田中 研太郎 氏 (東京工業大学)
条件付き独立性と線形代数 (JAPANESE)
[ 講演概要 ]
確率モデルにおける条件付き独立性の構造を表す手法として, グラフを用いた表現手法(グラフィカルモデリング)がよく使われる. しかし, グラフでは表すことのできない条件付き独立性の構造を持つ確率モデルが多数存在することが知られている. この欠点を克服するために, imset と呼ばれるものを用いた線形代数的な表現手法が Studeny(2005) によって提案されている. 今回の発表では, まず, imset について分かりやすく説明した後, 条件付き独立性の間に成り立つ関係式を自動的に導出する最近の手法について報告する. また, ベイジアンネットワークのデータからの構造推定に対する応用についても簡単に解説する.
[ 講演参考URL ]
http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2012/12.html

2012年12月05日(水)

PDE実解析研究会

10:30-11:30   数理科学研究科棟(駒場) 002号室
北海道大学のHPには、第1回(2004年9月29日)~第38回(2008年10月15日)までの情報が掲載されております。
Jie Jiang 氏 (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences)
Convergence to Equilibrium of Bounded Solutions with Application of Lojasiewicz-Simon's inequality (ENGLISH)
[ 講演概要 ]
In this talk, we present the application of Lojasiewicz-Simon's inequality to the study on convergence of bounded global solutions to some evolution equations. We take a semi-linear parabolic initial-boundary problem as an example. With the help of Lojasiewicz-Simon's inequality we prove that the bounded global solution will converge to an equilibrium as time goes to infinity provided the nonlinear term is analytic in the unknown function. We also present the application of Lojasiewicz-Simon's inequality to the asymptotic behavior studies on phase-field models with Cattaneo law and chemotaxis models with volume-filling effect.

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
谷本溶 氏 (Univ. Goettingen)
Construction of two dimensional QFT through Longo-Witten endomorphisms (JAPANESE)

幾何コロキウム

10:30-12:00   数理科学研究科棟(駒場) 128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.
石田 裕昭 氏 (大阪市立大学数学研究所)
Maximal torus actions on complex manifolds (JAPANESE)
[ 講演概要 ]
We say that an effective action of a compact torus $T$ on a connected manifold $M$ is maximal if there is an orbit of dimension $2\\dim T-\\dim M$. In this talk, we give a one-to-one correspondence between the family of connected closed complex manifolds with maximal torus actions and the family of certain combinatorial objects, which is a generalization of the correspondence between complete nonsingular toric varieties and nonsingular complete fans. As an application, we construct a lot of concrete examples of non-K\\"{a}hler manifolds with maximal torus actions.

古典解析セミナー

16:00-17:30   数理科学研究科棟(駒場) 270号室
Andrei Kapaev 氏 (SISSA, Trieste, Italy)
On the Riemann-Hilbert approach to the Malgrange divisor: $P_I^2$ case (ENGLISH)
[ 講演概要 ]
Equation $P_I^2$ is the second member in the hierarchy of ODEs associated with the classical Painlev\\’e first equation $P_I$ and can be solved via the Riemann-Hilbert (RH) problem approach. It is known also that solutions of equation $P_I^2$ as the functions of $x$ depending on the parameter $t$ can be used to construct a 4-parameter family of isomonodromic solutions to the KdV equation. Given the monodromy data, the set of points $(x,t)$, where the above mentioned RH problem is not solvable, is called the Malgrange divisor. The function $x=a(t)$, which parametrizes locally the Malgrange divisor, satisfies a nonlinear ODE which admits a Lax pair representation and can be also studied using an RH problem. We discuss the relations between these two kinds of the RH problems and the properties of their $t$-large genus 1 asymptotic solutions.

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