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Seminar information archive
Seminar information archive ～04/18｜Today's seminar 04/19 | Future seminars 04/20～
2013/06/04
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Mustafa Korkmaz (Middle East Technical University)
Low-dimensional linear representations of mapping class groups. (ENGLISH)
Mustafa Korkmaz (Middle East Technical University)
Low-dimensional linear representations of mapping class groups. (ENGLISH)
[ Abstract ]
For a compact connected orientable surface, the mapping class group
of it is defined as the group of isotopy classes of orientation-preserving
self-diffeomorphisms of S which are identity on the boundary. The action
of the mapping class group on the first homology of the surface
gives rise to the classical 2g-dimensional symplectic representation.
The existence of a faithful linear representation of the mapping class
group is still unknown. In my talk, I will show the following three results;
there is no lower dimensional (complex) linear representation,
up to conjugation the symplectic representation is the unique nontrivial representation in dimension 2g, and there is no faithful linear representation
of the mapping class group in dimensions up to 3g-3. I will also discuss a few applications of these theorems, including some algebraic consequences.
For a compact connected orientable surface, the mapping class group
of it is defined as the group of isotopy classes of orientation-preserving
self-diffeomorphisms of S which are identity on the boundary. The action
of the mapping class group on the first homology of the surface
gives rise to the classical 2g-dimensional symplectic representation.
The existence of a faithful linear representation of the mapping class
group is still unknown. In my talk, I will show the following three results;
there is no lower dimensional (complex) linear representation,
up to conjugation the symplectic representation is the unique nontrivial representation in dimension 2g, and there is no faithful linear representation
of the mapping class group in dimensions up to 3g-3. I will also discuss a few applications of these theorems, including some algebraic consequences.
Numerical Analysis Seminar
16:30-18:00 Room #002 (Graduate School of Math. Sci. Bldg.)
Takaharu Yaguchi (Kobe University )
On the theories of discrete differential forms and their applications to structure-preserving numerical methods (JAPANESE)
[ Reference URL ]
http://www.infsup.jp/utnas/
Takaharu Yaguchi (Kobe University )
On the theories of discrete differential forms and their applications to structure-preserving numerical methods (JAPANESE)
[ Reference URL ]
http://www.infsup.jp/utnas/
2013/06/03
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Takao Akahori (University of Hyogo)
Generalized deformation theory of CR structures (JAPANESE)
Takao Akahori (University of Hyogo)
Generalized deformation theory of CR structures (JAPANESE)
[ Abstract ]
Let $(M, {}^0 T^{''})$ be a compact strongly pseudo convex CR manifold with dimension $2n-1 \geq 5$, embedded in a complex manifold $N$ as a real hypersurface. In our former papers (T. Akahori, Invent. Math. 63 (1981); T. Akahori, P. M. Garfield, and J. M. Lee, Michigan Math. J. 50 (2002)), we constructed the versal family of CR structures. The purpose of this talk is to show that in more wide scope, our family is versal.
Let $(M, {}^0 T^{''})$ be a compact strongly pseudo convex CR manifold with dimension $2n-1 \geq 5$, embedded in a complex manifold $N$ as a real hypersurface. In our former papers (T. Akahori, Invent. Math. 63 (1981); T. Akahori, P. M. Garfield, and J. M. Lee, Michigan Math. J. 50 (2002)), we constructed the versal family of CR structures. The purpose of this talk is to show that in more wide scope, our family is versal.
2013/05/31
Colloquium
16:30-17:30 Room #002 (Graduate School of Math. Sci. Bldg.)
Yasuhito MIYAMOTO (Graduate School of Mathematical Sciences, The University of Tokyo)
Stable patterns and the nonlinear ``hot spots'' conjecture (JAPANESE)
Yasuhito MIYAMOTO (Graduate School of Mathematical Sciences, The University of Tokyo)
Stable patterns and the nonlinear ``hot spots'' conjecture (JAPANESE)
2013/05/30
FMSP Lectures
13:00-14:30 Room #122 (Graduate School of Math. Sci. Bldg.)
Mustafa Korkmaz (Middle East Technical University)
Low-dimensional linear representations of mapping class groups (III) (ENGLISH)
[ Reference URL ]
http://faculty.ms.u-tokyo.ac.jp/~topology/Korkmaz.pdf
Mustafa Korkmaz (Middle East Technical University)
Low-dimensional linear representations of mapping class groups (III) (ENGLISH)
[ Reference URL ]
http://faculty.ms.u-tokyo.ac.jp/~topology/Korkmaz.pdf
2013/05/29
FMSP Lectures
13:00-14:30 Room #122 (Graduate School of Math. Sci. Bldg.)
Mustafa Korkmaz (Middle East Technical University)
Low-dimensional linear representations of mapping class groups (II) (ENGLISH)
[ Reference URL ]
http://faculty.ms.u-tokyo.ac.jp/~topology/Korkmaz.pdf
Mustafa Korkmaz (Middle East Technical University)
Low-dimensional linear representations of mapping class groups (II) (ENGLISH)
[ Reference URL ]
http://faculty.ms.u-tokyo.ac.jp/~topology/Korkmaz.pdf
Number Theory Seminar
16:40-17:40 Room #002 (Graduate School of Math. Sci. Bldg.)
Sachio Ohkawa (University of Tokyo)
On logarithmic nonabelian Hodge theory of higher level in characteristic p (JAPANESE)
Sachio Ohkawa (University of Tokyo)
On logarithmic nonabelian Hodge theory of higher level in characteristic p (JAPANESE)
[ Abstract ]
Ogus and Vologodsky studied a positive characteristic analogue of Simpson’s nonanelian Hodge theory over the complex number field. Now most part of their theory has been generalized to the case of log schemes by Schepler. In this talk, we generalize the global Cartier transform, which is one of the main theorem in nonabelian Hodge theory in positive characteristic, to the case of log schemes and of higher level. This can be regarded as a higher level version of a result of Schepler.
Ogus and Vologodsky studied a positive characteristic analogue of Simpson’s nonanelian Hodge theory over the complex number field. Now most part of their theory has been generalized to the case of log schemes by Schepler. In this talk, we generalize the global Cartier transform, which is one of the main theorem in nonabelian Hodge theory in positive characteristic, to the case of log schemes and of higher level. This can be regarded as a higher level version of a result of Schepler.
Operator Algebra Seminars
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Yuki Arano (Univ. Tokyo)
On full group C*-algebras of discrete quantum groups (ENGLISH)
Yuki Arano (Univ. Tokyo)
On full group C*-algebras of discrete quantum groups (ENGLISH)
2013/05/28
FMSP Lectures
17:10-18:40 Room #117 (Graduate School of Math. Sci. Bldg.)
Mustafa Korkmaz (Middle East Technical University)
Low-dimensional linear representations of mapping class groups (I) (ENGLISH)
[ Reference URL ]
http://faculty.ms.u-tokyo.ac.jp/~topology/Korkmaz.pdf
Mustafa Korkmaz (Middle East Technical University)
Low-dimensional linear representations of mapping class groups (I) (ENGLISH)
[ Reference URL ]
http://faculty.ms.u-tokyo.ac.jp/~topology/Korkmaz.pdf
2013/05/27
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Tomohiro Okuma (Yamagata University)
2次元擬斉次特異点の接層のコホモロジーについて (JAPANESE)
Tomohiro Okuma (Yamagata University)
2次元擬斉次特異点の接層のコホモロジーについて (JAPANESE)
[ Abstract ]
複素2次元特異点の特異点解消上の接層のコホモロジーの次元は解析的不変量である. セミナーでは, リンクが有理ホモロジー球面であるような2次元擬斉次特異点の場合にはそれが位相的不変量であり, グラフから計算できることを紹介する.
複素2次元特異点の特異点解消上の接層のコホモロジーの次元は解析的不変量である. セミナーでは, リンクが有理ホモロジー球面であるような2次元擬斉次特異点の場合にはそれが位相的不変量であり, グラフから計算できることを紹介する.
2013/05/25
Harmonic Analysis Komaba Seminar
13:00-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)
Takeshi Iida (Fukushima National College of Technology) 13:30-15:00
Multilinear fractional integral operators on weighted Morrey spaces (JAPANESE)
Yasunori Maekawa (Tohoku University) 15:30-17:00
On factorization of divergence form elliptic operators
and its application
(JAPANESE)
Takeshi Iida (Fukushima National College of Technology) 13:30-15:00
Multilinear fractional integral operators on weighted Morrey spaces (JAPANESE)
Yasunori Maekawa (Tohoku University) 15:30-17:00
On factorization of divergence form elliptic operators
and its application
(JAPANESE)
2013/05/24
Lectures
16:30-18:00 Room #002 (Graduate School of Math. Sci. Bldg.)
Laurent Lafforgue (IHES)
Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (JAPANESE)
Laurent Lafforgue (IHES)
Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (JAPANESE)
2013/05/21
Tuesday Seminar of Analysis
16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)
Masaaki Uesaka (Graduate School of Mathematical Sciences, The University of Tokyo)
Homogenization in a Thin Layer with an Oscillating Interface and Highly Contrast Coefficients (JAPANESE)
Masaaki Uesaka (Graduate School of Mathematical Sciences, The University of Tokyo)
Homogenization in a Thin Layer with an Oscillating Interface and Highly Contrast Coefficients (JAPANESE)
[ Abstract ]
We consider the homogenization problem of the elliptic boundary value problem in a thin domain which has a high and low conductivity zones. In our model, two media are separated by a highly oscillating interface. The asymptotic behavior is governed by the order of the thickness of the domain, oscillation period of the interface and contrast between two media. In this talk, we show that the limit problem is changed by these parameters. We also introduce the two-scale convergence result in a thin domain which is the key ingredient of the proof.
We consider the homogenization problem of the elliptic boundary value problem in a thin domain which has a high and low conductivity zones. In our model, two media are separated by a highly oscillating interface. The asymptotic behavior is governed by the order of the thickness of the domain, oscillation period of the interface and contrast between two media. In this talk, we show that the limit problem is changed by these parameters. We also introduce the two-scale convergence result in a thin domain which is the key ingredient of the proof.
Lectures
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Laurent Lafforgue (IHES)
Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)
Laurent Lafforgue (IHES)
Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Yuanyuan Bao (The University of Tokyo)
A Heegaard Floer homology for bipartite spatial graphs and its
properties (ENGLISH)
Yuanyuan Bao (The University of Tokyo)
A Heegaard Floer homology for bipartite spatial graphs and its
properties (ENGLISH)
[ Abstract ]
A spatial graph is a smooth embedding of a graph into a given
3-manifold. We can regard a link as a particular spatial graph.
So it is natural to ask whether it is possible to extend the idea
of link Floer homology to define a Heegaard Floer homology for
spatial graphs. In this talk, we discuss some ideas towards this
question. In particular, we define a Heegaard Floer homology for
bipartite spatial graphs and discuss some further observations
about this construction. We remark that Harvey and O’Donnol
have announced a combinatorial Floer homology for spatial graphs by
considering grid diagrams.
A spatial graph is a smooth embedding of a graph into a given
3-manifold. We can regard a link as a particular spatial graph.
So it is natural to ask whether it is possible to extend the idea
of link Floer homology to define a Heegaard Floer homology for
spatial graphs. In this talk, we discuss some ideas towards this
question. In particular, we define a Heegaard Floer homology for
bipartite spatial graphs and discuss some further observations
about this construction. We remark that Harvey and O’Donnol
have announced a combinatorial Floer homology for spatial graphs by
considering grid diagrams.
2013/05/20
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Takeo Ohsawa (Nagoya University)
レヴィ平坦面の分類に関する最近の進展 (JAPANESE)
Takeo Ohsawa (Nagoya University)
レヴィ平坦面の分類に関する最近の進展 (JAPANESE)
[ Abstract ]
レヴィ平坦面の分類がCP^2の場合にできていないことから、種々の興味深い問題が生じているように思われる。ここではトーラスの場合に観察されたことをホップ曲面に拡げたとき、ホップ曲面においてならレヴィ平坦面の分類が(実解析的な場合に限るが)完全にできることを報告する。
レヴィ平坦面の分類がCP^2の場合にできていないことから、種々の興味深い問題が生じているように思われる。ここではトーラスの場合に観察されたことをホップ曲面に拡げたとき、ホップ曲面においてならレヴィ平坦面の分類が(実解析的な場合に限るが)完全にできることを報告する。
2013/05/17
Seminar on Probability and Statistics
13:30-14:40 Room #052 (Graduate School of Math. Sci. Bldg.)
SEI, Tomonari (Department of Mathematics, Keio University)
Computing the normalizing constant of the Bingham family by the holonomic gradient method (JAPANESE)
[ Reference URL ]
http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/00.html
SEI, Tomonari (Department of Mathematics, Keio University)
Computing the normalizing constant of the Bingham family by the holonomic gradient method (JAPANESE)
[ Reference URL ]
http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/00.html
2013/05/16
Geometry Colloquium
10:00-11:30 Room #122 (Graduate School of Math. Sci. Bldg.)
Kota Hattori (University of Tokyo)
A generalization of Taub-NUT deformations (JAPANESE)
Kota Hattori (University of Tokyo)
A generalization of Taub-NUT deformations (JAPANESE)
[ Abstract ]
Taub-NUT metric on C^2 is a complete Ricci-flat Kaehler metric which is not flat. It is obtained by the Taub-NUT deformations of the Euclidean metric on C^2 using an S^1 action. Taub-NUT deformations are known to be defined for toric hyperKaehler manifolds, and deform ALE metrics to non-ALE metrics. In this talk, I explain a generalization of Taub-NUT deformations by using noncommutative Lie groups.
Taub-NUT metric on C^2 is a complete Ricci-flat Kaehler metric which is not flat. It is obtained by the Taub-NUT deformations of the Euclidean metric on C^2 using an S^1 action. Taub-NUT deformations are known to be defined for toric hyperKaehler manifolds, and deform ALE metrics to non-ALE metrics. In this talk, I explain a generalization of Taub-NUT deformations by using noncommutative Lie groups.
2013/05/15
Operator Algebra Seminars
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Koichi Shimada (Univ. Tokyo)
Rohlin Flows on Amalgamated Free Product Factors (ENGLISH)
Koichi Shimada (Univ. Tokyo)
Rohlin Flows on Amalgamated Free Product Factors (ENGLISH)
Number Theory Seminar
16:40-17:40 Room #056 (Graduate School of Math. Sci. Bldg.)
Hiroyasu Miyazaki (University of Tokyo)
Special values of zeta functions of singular varieties over finite fields via higher chow groups (JAPANESE)
Hiroyasu Miyazaki (University of Tokyo)
Special values of zeta functions of singular varieties over finite fields via higher chow groups (JAPANESE)
2013/05/14
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Kenta Hayano (Osaka University)
Vanishing cycles and homotopies of wrinkled fibrations (JAPANESE)
Kenta Hayano (Osaka University)
Vanishing cycles and homotopies of wrinkled fibrations (JAPANESE)
[ Abstract ]
Wrinkled fibrations on closed 4-manifolds are stable
maps to closed surfaces with only indefinite singularities. Such
fibrations and variants of them have been studied for the past few years
to obtain new descriptions of 4-manifolds using mapping class groups.
Vanishing cycles of wrinkled fibrations play a key role in these studies.
In this talk, we will explain how homotopies of wrinkled fibrtions affect
their vanishing cycles. Part of the results in this talk is a joint work
with Stefan Behrens (Max Planck Institute for Mathematics).
Wrinkled fibrations on closed 4-manifolds are stable
maps to closed surfaces with only indefinite singularities. Such
fibrations and variants of them have been studied for the past few years
to obtain new descriptions of 4-manifolds using mapping class groups.
Vanishing cycles of wrinkled fibrations play a key role in these studies.
In this talk, we will explain how homotopies of wrinkled fibrtions affect
their vanishing cycles. Part of the results in this talk is a joint work
with Stefan Behrens (Max Planck Institute for Mathematics).
Lectures
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Laurent Lafforgue (IHES)
Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)
Laurent Lafforgue (IHES)
Kernels of Langlands' automorphic transfer and non-linear Poisson formulas (ENGLISH)
2013/05/13
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Yusuke Okuyama (Kyoto Institute of Technology)
Geometry and analysis of isolated essential singularities and their applications (JAPANESE)
Yusuke Okuyama (Kyoto Institute of Technology)
Geometry and analysis of isolated essential singularities and their applications (JAPANESE)
[ Abstract ]
We establish a rescaling principle for isolated essential singularities of holomorphic curves and quasiregular mappings, and gives several applications of it in the theory of value distribution and dynamics. This is a joint work with Pekka Pankka.
We establish a rescaling principle for isolated essential singularities of holomorphic curves and quasiregular mappings, and gives several applications of it in the theory of value distribution and dynamics. This is a joint work with Pekka Pankka.
2013/05/11
Monthly Seminar on Arithmetic of Automorphic Forms
13:30-16:00 Room #123 (Graduate School of Math. Sci. Bldg.)
Taku Ishii (Seikei Univeristy) 13:30-14:30
Symplectic-orthogonal theta lifts and explicit formulas for archimedean Whittaker functions (JAPANESE)
Takashi Ichikawa (Saga University) 15:00-16:00
Infinite product represenation of the Mumford form and its application to the values of Selberg zeta functions (JAPANESE)
Taku Ishii (Seikei Univeristy) 13:30-14:30
Symplectic-orthogonal theta lifts and explicit formulas for archimedean Whittaker functions (JAPANESE)
Takashi Ichikawa (Saga University) 15:00-16:00
Infinite product represenation of the Mumford form and its application to the values of Selberg zeta functions (JAPANESE)
Infinite Analysis Seminar Tokyo
10:30-12:00 Room #117 (Graduate School of Math. Sci. Bldg.)
Anatol Kirillov (RIMS Kyoto Univ.)
Saga of Dunkl elements (ENGLISH)
Anatol Kirillov (RIMS Kyoto Univ.)
Saga of Dunkl elements (ENGLISH)
[ Abstract ]
The Dunkl operators has been introduced by C. Dunkl in the middle of
80's of the last century as a powerful mean in the study of orthogonal
polynomials related with finite Coxeter groups. Later it was discovered
a deep connection of the the Dunkl operators with the theory of
Integrable systems and Invariant Theory.
In my talk I introduce and study a certain class of nonhomogeneous
quadratic algebras together with the distinguish set of mutually
commuting elements inside of each, the so-called universal Dunkl elements.
The main problem I would like to discuss is : What is the algebra
generated by universal Dunkl elements in a different representations of
the quadratic algebra introduced ?
I'm planning to present partial answers on that problem related with
classical and quantum Schubert and Grothendieck Calculi as well as the
theory of elliptic series.
Also some interesting algebraic properties of the quadratic algebra(s)
in question will be described.
The Dunkl operators has been introduced by C. Dunkl in the middle of
80's of the last century as a powerful mean in the study of orthogonal
polynomials related with finite Coxeter groups. Later it was discovered
a deep connection of the the Dunkl operators with the theory of
Integrable systems and Invariant Theory.
In my talk I introduce and study a certain class of nonhomogeneous
quadratic algebras together with the distinguish set of mutually
commuting elements inside of each, the so-called universal Dunkl elements.
The main problem I would like to discuss is : What is the algebra
generated by universal Dunkl elements in a different representations of
the quadratic algebra introduced ?
I'm planning to present partial answers on that problem related with
classical and quantum Schubert and Grothendieck Calculi as well as the
theory of elliptic series.
Also some interesting algebraic properties of the quadratic algebra(s)
in question will be described.
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