Text only print
Full screen print
Seminar information archive
Seminar information archive ～10/03｜Today's seminar 10/04 | Future seminars 10/05～
Mathematical Biology Seminar
15:00-16:20 Room #056 (Graduate School of Math. Sci. Bldg.)
Odo Diekmann (Mathematical Institute, Utrecht University)
The delay equation formulation of physiologically structured population models
Odo Diekmann (Mathematical Institute, Utrecht University)
The delay equation formulation of physiologically structured population models
[ Abstract ]
Traditionally, physiologically structured population models are formulated in terms of first order partial differential equations with non-local boundary conditions and/or transformed arguments. The stability and bifurcation theory for such equations is, in the quasi-linear case, still very immature.
The aim of this lecture is to explain that, alternatively, one can formulate such models in terms of delay equations (more precisely : renewal equations coupled to delay differential equations) without losing essential information and that for delay equations there is a well-developed local stability and bifurcation theory. As a motivating example we consider the interaction between a size-structured consumer and an unstructured resource. The lecture is based on joint work with Mats Gyllenberg and Hans Metz.
Traditionally, physiologically structured population models are formulated in terms of first order partial differential equations with non-local boundary conditions and/or transformed arguments. The stability and bifurcation theory for such equations is, in the quasi-linear case, still very immature.
The aim of this lecture is to explain that, alternatively, one can formulate such models in terms of delay equations (more precisely : renewal equations coupled to delay differential equations) without losing essential information and that for delay equations there is a well-developed local stability and bifurcation theory. As a motivating example we consider the interaction between a size-structured consumer and an unstructured resource. The lecture is based on joint work with Mats Gyllenberg and Hans Metz.
2009/07/14
Tuesday Seminar on Topology
17:00-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
作間 誠 (広島大学)
The Cannon-Thurston maps and the canonical decompositions
of punctured-torus bundles over the circle.
作間 誠 (広島大学)
The Cannon-Thurston maps and the canonical decompositions
of punctured-torus bundles over the circle.
[ Abstract ]
To each once-punctured-torus bundle over the circle
with pseudo-Anosov monodromy, there are associated two tessellations of the complex plane:
one is the triangulation of a horosphere induced by the canonical decomposition into ideal
tetrahedra, and the other is a fractal tessellation
given by the Cannon-Thurston map of the fiber group.
In this talk, I will explain the relation between these two tessellations
(joint work with Warren Dicks).
I will also explain the relation of the fractal tessellation and
the "circle chains" of double cusp groups converging to the fiber group
(joint work with Caroline Series).
If time permits, I would like to discuss possible generalization of these results
to higher-genus punctured surface bundles.
To each once-punctured-torus bundle over the circle
with pseudo-Anosov monodromy, there are associated two tessellations of the complex plane:
one is the triangulation of a horosphere induced by the canonical decomposition into ideal
tetrahedra, and the other is a fractal tessellation
given by the Cannon-Thurston map of the fiber group.
In this talk, I will explain the relation between these two tessellations
(joint work with Warren Dicks).
I will also explain the relation of the fractal tessellation and
the "circle chains" of double cusp groups converging to the fiber group
(joint work with Caroline Series).
If time permits, I would like to discuss possible generalization of these results
to higher-genus punctured surface bundles.
2009/07/13
Algebraic Geometry Seminar
16:30-18:00 Room #126 (Graduate School of Math. Sci. Bldg.)
佐野 太郎 (東大数理)
Seshadri constants on rational surfaces with anticanonical pencils
佐野 太郎 (東大数理)
Seshadri constants on rational surfaces with anticanonical pencils
[ Abstract ]
射影多様体上の豊富線束の$k$-jet ample性を測る不変量として
Seshadri定数と呼ばれる正の実数がある。
この不変量を調べることでしばしば幾何的な情報が得られる。
今回、1次元以上の反標準線形系をもつ有理曲面上のSeshadri定数を計算する公式
が得られた。
その公式を使うと、対数del Pezzo曲面の特異点の情報をSeshadri定数の値から
復元できる。
射影多様体上の豊富線束の$k$-jet ample性を測る不変量として
Seshadri定数と呼ばれる正の実数がある。
この不変量を調べることでしばしば幾何的な情報が得られる。
今回、1次元以上の反標準線形系をもつ有理曲面上のSeshadri定数を計算する公式
が得られた。
その公式を使うと、対数del Pezzo曲面の特異点の情報をSeshadri定数の値から
復元できる。
2009/07/09
Operator Algebra Seminars
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Mikael Pichot (東大数物連携宇宙研究機構)
Examples of groups of intermediate rank
Mikael Pichot (東大数物連携宇宙研究機構)
Examples of groups of intermediate rank
2009/07/06
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
赤堀隆夫 (兵庫県立大学)
On the CR Hamiltonian flows
赤堀隆夫 (兵庫県立大学)
On the CR Hamiltonian flows
[ Abstract ]
The deformation theory of CR structures was initiated by Kuranishi and the versal family of CR structures were constructed by Garfied, Lee and myself "in the sense of Kuranishi". Miyajima also discussed the versal family by the completely different method. While, our method relies on the contact geometry(this suggest that there is a deep relation between Hamiltonian geometry and CR structures). Today, I report that our family is also versal "in the sense of CR Hamiltonian flows".
The deformation theory of CR structures was initiated by Kuranishi and the versal family of CR structures were constructed by Garfied, Lee and myself "in the sense of Kuranishi". Miyajima also discussed the versal family by the completely different method. While, our method relies on the contact geometry(this suggest that there is a deep relation between Hamiltonian geometry and CR structures). Today, I report that our family is also versal "in the sense of CR Hamiltonian flows".
Algebraic Geometry Seminar
16:30-18:00 Room #126 (Graduate School of Math. Sci. Bldg.)
柳田 伸太郎 (神戸大学理学研究科)
アーベル曲面上の安定層とフーリエ向井変換について
柳田 伸太郎 (神戸大学理学研究科)
アーベル曲面上の安定層とフーリエ向井変換について
[ Abstract ]
今回の講演は吉岡康太との共同研究に基づくものである. 研究の発端は, 向井茂が1980年前後(フーリエ向井変換の発見前後)に考察し, 当時の講演記録に書き残した主張や予想の解読にある.
本研究は, 大まかに言うと, 半等質層とフーリエ向井変換を用いて, アーベル曲面上の安定層のモジュライ空間の構造を調べるというものである.
アーベル曲面上には半等質層と呼ばれる半安定層があり, その分類, 構成方法やコホモロジーが完全に知られている. アーベル曲面のフーリエ向井対は半等質層のモジュライ空間であることも知られている.
今回の研究はこの半等質層をbulding blockとして一般の安定層を構成することを考える. その際に"semi-homogeneous presentation"という概念が必要になる. これはアーベル曲面上の安定層の半等質層によるある種の分解のことである. 曲面のピカール数が1の時, この種の分解の存在が安定層のチャーン指標のみを用いて判定できる.
また安定層のフーリエ変換における振舞いの記述において, 算術群や整数係数2次形式が重要な役割を果たすことも分かる. この事と先に述べた表示の存在から, 安定層のモジュライとアーベル曲面上の点のヒルベルトスキームとの間の双有理変換が明示的に構成できる.
アーベル曲面のフーリエ向井変換のフォーマリズムはK3曲面の変換と共通する部分も少なくない. 講演ではそうした点にも触れつつ, 今回の結果とその証明の概要を解説したい.
今回の講演は吉岡康太との共同研究に基づくものである. 研究の発端は, 向井茂が1980年前後(フーリエ向井変換の発見前後)に考察し, 当時の講演記録に書き残した主張や予想の解読にある.
本研究は, 大まかに言うと, 半等質層とフーリエ向井変換を用いて, アーベル曲面上の安定層のモジュライ空間の構造を調べるというものである.
アーベル曲面上には半等質層と呼ばれる半安定層があり, その分類, 構成方法やコホモロジーが完全に知られている. アーベル曲面のフーリエ向井対は半等質層のモジュライ空間であることも知られている.
今回の研究はこの半等質層をbulding blockとして一般の安定層を構成することを考える. その際に"semi-homogeneous presentation"という概念が必要になる. これはアーベル曲面上の安定層の半等質層によるある種の分解のことである. 曲面のピカール数が1の時, この種の分解の存在が安定層のチャーン指標のみを用いて判定できる.
また安定層のフーリエ変換における振舞いの記述において, 算術群や整数係数2次形式が重要な役割を果たすことも分かる. この事と先に述べた表示の存在から, 安定層のモジュライとアーベル曲面上の点のヒルベルトスキームとの間の双有理変換が明示的に構成できる.
アーベル曲面のフーリエ向井変換のフォーマリズムはK3曲面の変換と共通する部分も少なくない. 講演ではそうした点にも触れつつ, 今回の結果とその証明の概要を解説したい.
2009/07/02
Operator Algebra Seminars
17:00-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
小沢登高 (東大数理)
Dixmier's Similarity Problem ---Littlewood and Forests--- (一般の数学者向け)
小沢登高 (東大数理)
Dixmier's Similarity Problem ---Littlewood and Forests--- (一般の数学者向け)
2009/07/01
Lectures
15:30-17:00 Room #470 (Graduate School of Math. Sci. Bldg.)
金井 政宏 (東大数理)
ASEPおよびzero-range processの分配関数
金井 政宏 (東大数理)
ASEPおよびzero-range processの分配関数
2009/06/30
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
北山 貴裕 (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
北山 貴裕 (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
[ Abstract ]
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.
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.
Tuesday Seminar of Analysis
16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)
Ivana Alexandrova (東京大数理)
The Structure of the Scattering Amplitude for Schrodinger Operators with a Strong Magnetic Field
Ivana Alexandrova (東京大数理)
The Structure of the Scattering Amplitude for Schrodinger Operators with a Strong Magnetic Field
[ Abstract ]
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.
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.
2009/06/29
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
藤木 明 (大阪大学)
VII型曲面上の反自己双対双エルミート構造の存在について
藤木 明 (大阪大学)
VII型曲面上の反自己双対双エルミート構造の存在について
Algebraic Geometry Seminar
16:30-18:00 Room #126 (Graduate School of Math. Sci. Bldg.)
大川 領 (東京工業大学)
Moduli on the projective plane and the wall-crossing
大川 領 (東京工業大学)
Moduli on the projective plane and the wall-crossing
[ Abstract ]
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
を用いることにより、ある有限次元代数の半安定表現のモジュライ空間
として構成する。階数が2以下の場合、表現の安定性条件を変化させること
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。
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
を用いることにより、ある有限次元代数の半安定表現のモジュライ空間
として構成する。階数が2以下の場合、表現の安定性条件を変化させること
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。
2009/06/25
Operator Algebra Seminars
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
鈴木章斗 (九州大学数理学研究院)
Infrared divergence of scalar quantum field model on pseudo Riemann manifold
鈴木章斗 (九州大学数理学研究院)
Infrared divergence of scalar quantum field model on pseudo Riemann manifold
2009/06/24
Number Theory Seminar
16:30-18:45 Room #056 (Graduate School of Math. Sci. Bldg.)
Vincent Maillot (Paris第7大学) 16:30-17:30
New algebraicity results for analytic torsion
Richard Hain (Duke大学) 17:45-18:45
On the Section Conjecture for the universal curve over function fields
Vincent Maillot (Paris第7大学) 16:30-17:30
New algebraicity results for analytic torsion
Richard Hain (Duke大学) 17:45-18:45
On the Section Conjecture for the universal curve over function fields
PDE Real Analysis Seminar
10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)
Winston Ou (Scripps College / currently visiting assistant professor at Keio University)
Monge-Ampere equations, the Bellman Function Technique, and Muckenhoupt weights
Winston Ou (Scripps College / currently visiting assistant professor at Keio University)
Monge-Ampere equations, the Bellman Function Technique, and Muckenhoupt weights
[ Abstract ]
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.
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.
Lectures
15:30-17:00 Room #122 (Graduate School of Math. Sci. Bldg.)
柳尾 朋洋 (早大 基幹理工)
原子・分子集合体の集団運動における動的秩序と階層性
柳尾 朋洋 (早大 基幹理工)
原子・分子集合体の集団運動における動的秩序と階層性
[ Abstract ]
小さな気体分子の化学反応から、結晶成長、さらにはDNAやタンパク質のような生体高分子の機能発現に至るまで、原子・分子集合体の集団運動と自己組織化の一般原理を明らかにすることは、現代科学の大変興味深い課題である。近年の実験技術の進歩により、これら原子分子系の集団運動の多くは、平衡状態から大きく離れた非平衡状態において発生し、動的な秩序を内包していることが明らかになってきている。本発表では、一例として原子クラスターの構造変化の集団運動を取り上げ、これらの集団運動が、「遅い自由度」と「速い自由度」の間の動的結合によって系統的に生み出される仕組みについて紹介する。あわせて、このような非平衡過程を記述する新たな反応速度論の試みについても紹介する。続いて、より複雑な分子系の例として、生物のDNAをとりあげ、ランジュバン動力学に基づく粗視化モデルを導入することによって、DNAが細胞中で階層的な秩序構造を形成するメカニズムの一端を明らかにする。
小さな気体分子の化学反応から、結晶成長、さらにはDNAやタンパク質のような生体高分子の機能発現に至るまで、原子・分子集合体の集団運動と自己組織化の一般原理を明らかにすることは、現代科学の大変興味深い課題である。近年の実験技術の進歩により、これら原子分子系の集団運動の多くは、平衡状態から大きく離れた非平衡状態において発生し、動的な秩序を内包していることが明らかになってきている。本発表では、一例として原子クラスターの構造変化の集団運動を取り上げ、これらの集団運動が、「遅い自由度」と「速い自由度」の間の動的結合によって系統的に生み出される仕組みについて紹介する。あわせて、このような非平衡過程を記述する新たな反応速度論の試みについても紹介する。続いて、より複雑な分子系の例として、生物のDNAをとりあげ、ランジュバン動力学に基づく粗視化モデルを導入することによって、DNAが細胞中で階層的な秩序構造を形成するメカニズムの一端を明らかにする。
2009/06/23
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
久野 雄介 (東京大学大学院数理科学研究科)
The Meyer functions for projective varieties and their applications
久野 雄介 (東京大学大学院数理科学研究科)
The Meyer functions for projective varieties and their applications
[ Abstract ]
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
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
Algebraic Geometry Seminar
16:30-18:00 Room #126 (Graduate School of Math. Sci. Bldg.)
岸本崇氏 (埼玉大学理工学研究科)
Group actions on affine cones
岸本崇氏 (埼玉大学理工学研究科)
Group actions on affine cones
[ Abstract ]
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_+.
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_+.
2009/06/22
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
早乙女飛成 (筑波大学)
強疑凸多様体間の擬正則写像の楕円型作用素に関する性質について
早乙女飛成 (筑波大学)
強疑凸多様体間の擬正則写像の楕円型作用素に関する性質について
2009/06/20
Monthly Seminar on Arithmetic of Automorphic Forms
13:30-16:00 Room #123 (Graduate School of Math. Sci. Bldg.)
小池 健二 (山梨大学教育人間科学部) 13:30-14:30
射影直線上の6点とI型領域上のテータ関数
射影直線上の6点とI型領域上のテータ関数
成田宏秋 (熊本大学理学部) 15:00-16:00
Fourier coefficients of Arakawa lifting and some degree eight L-function
小池 健二 (山梨大学教育人間科学部) 13:30-14:30
射影直線上の6点とI型領域上のテータ関数
射影直線上の6点とI型領域上のテータ関数
成田宏秋 (熊本大学理学部) 15:00-16:00
Fourier coefficients of Arakawa lifting and some degree eight L-function
[ Abstract ]
次数2のシンプレクティック群ないしはその非コンパクトな内部形式上のヘッケ同時固有的保型形式のフーリエ係数は、保型L関数の中心値と密接に関係すると考えられている。
この講演では「荒川リフト」という内部形式上のカスプ形式に対し、そのフーリエ係数とある次数8の保型L関数の中心値との明示的な関係について最近得られた結果を紹介する。(村瀬篤氏との共同研究)
次数2のシンプレクティック群ないしはその非コンパクトな内部形式上のヘッケ同時固有的保型形式のフーリエ係数は、保型L関数の中心値と密接に関係すると考えられている。
この講演では「荒川リフト」という内部形式上のカスプ形式に対し、そのフーリエ係数とある次数8の保型L関数の中心値との明示的な関係について最近得られた結果を紹介する。(村瀬篤氏との共同研究)
Infinite Analysis Seminar Tokyo
11:00-12:00 Room #117 (Graduate School of Math. Sci. Bldg.)
有田親史 (九大数理)
多成分排他過程の固有値が満たす双対性
有田親史 (九大数理)
多成分排他過程の固有値が満たす双対性
[ Abstract ]
非対称単純排他過程(asymmetric simple exclusion process, ASEP)と呼ばれ
る1次元格子上の確率過程がある。今回はその多成分の場合を考える。系の時間
発展を特徴付けるジェネレータ行列(マルコフ行列)は,Heisenberg模型を含む
Perk-Schultz模型のハミルトニアンの特殊な場合と等価である。講演者らは各粒
子セクターを超立方体の頂点と対応させ固有値の構造を調べた。超立方体上で双
対点を成す2つのセクターの固有値が満たす関係を示した。国場敦夫氏,堺和光
氏,沢辺剛氏との共同研究。
非対称単純排他過程(asymmetric simple exclusion process, ASEP)と呼ばれ
る1次元格子上の確率過程がある。今回はその多成分の場合を考える。系の時間
発展を特徴付けるジェネレータ行列(マルコフ行列)は,Heisenberg模型を含む
Perk-Schultz模型のハミルトニアンの特殊な場合と等価である。講演者らは各粒
子セクターを超立方体の頂点と対応させ固有値の構造を調べた。超立方体上で双
対点を成す2つのセクターの固有値が満たす関係を示した。国場敦夫氏,堺和光
氏,沢辺剛氏との共同研究。
2009/06/18
Operator Algebra Seminars
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
河東泰之 (東大数理)
The super Virasoro algebra and noncommutative geometry
河東泰之 (東大数理)
The super Virasoro algebra and noncommutative geometry
2009/06/17
PDE Real Analysis Seminar
10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)
小磯深幸 (奈良女子大学理学部/JSTさきがけ)
Variational problems for anisotropic surface energies
小磯深幸 (奈良女子大学理学部/JSTさきがけ)
Variational problems for anisotropic surface energies
[ Abstract ]
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.
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.
2009/06/16
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
佐藤 正寿 (東京大学大学院数理科学研究科)
The abelianization of the level 2 mapping class group
佐藤 正寿 (東京大学大学院数理科学研究科)
The abelianization of the level 2 mapping class group
[ Abstract ]
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.
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.
2009/06/15
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
野口潤次郎 (東京大学)
A unicity theorem and Erdös' problem for polarized semi-abelian varieties (joint with P. Corvaja)
野口潤次郎 (東京大学)
A unicity theorem and Erdös' problem for polarized semi-abelian varieties (joint with P. Corvaja)
< Previous 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189 Next >
