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Seminar information archive
Seminar information archive ～07/25｜Today's seminar 07/26 | Future seminars 07/27～
2013/10/23
Operator Algebra Seminars
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Makoto Yamashita (Ochanomizu Univ.)
Classification of quantum homogeneous spaces (ENGLISH)
Makoto Yamashita (Ochanomizu Univ.)
Classification of quantum homogeneous spaces (ENGLISH)
Seminar on Probability and Statistics
13:00-15:30 Room #006 (Graduate School of Math. Sci. Bldg.)
Mark Podolskij (Universität Heidelberg)
Limit theorems for ambit processes (ENGLISH)
http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/04.html
Mark Podolskij (Universität Heidelberg)
Limit theorems for ambit processes (ENGLISH)
[ Abstract ]
We present some recent limit theorems for high frequency observations of ambit processes. Ambit processes constitute a flexible class of models, which are usually used to describe turbulent motion in physics. Mathematically speaking, they have a continuous moving average structure with additional random component called intermittency. In the first part of the lecture we will demonstrate the asymptotic theory for ambit processes driven by Brownian motion. The second part will deal with Levy driven ambit processes. We will see that these two cases deliver completely different limiting results.
本講演は数物フロンティア・リーディング大学院のレクチャーとして行います.
[ Reference URL ]We present some recent limit theorems for high frequency observations of ambit processes. Ambit processes constitute a flexible class of models, which are usually used to describe turbulent motion in physics. Mathematically speaking, they have a continuous moving average structure with additional random component called intermittency. In the first part of the lecture we will demonstrate the asymptotic theory for ambit processes driven by Brownian motion. The second part will deal with Levy driven ambit processes. We will see that these two cases deliver completely different limiting results.
本講演は数物フロンティア・リーディング大学院のレクチャーとして行います.
http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/04.html
2013/10/22
PDE Real Analysis Seminar
10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)
Armin Schikorra (MPI for Mathematics in the Sciences, Leipzig)
Fractional harmonic maps and applications (ENGLISH)
Armin Schikorra (MPI for Mathematics in the Sciences, Leipzig)
Fractional harmonic maps and applications (ENGLISH)
[ Abstract ]
Fractional harmonic mappings are critical points of a generalized Dirichlet Energy where the gradient is replaced with a (non-local) differential operator.
I will present aspects of the regularity theory of (non-local) fractional harmonic maps into manifolds, which extends (and contains) the theory of (poly-)harmonic mappings.
I also will mention, how one can show regularity for critical points of the Moebius (Knot-) Energy, applying the techniques developed in this theory.
Fractional harmonic mappings are critical points of a generalized Dirichlet Energy where the gradient is replaced with a (non-local) differential operator.
I will present aspects of the regularity theory of (non-local) fractional harmonic maps into manifolds, which extends (and contains) the theory of (poly-)harmonic mappings.
I also will mention, how one can show regularity for critical points of the Moebius (Knot-) Energy, applying the techniques developed in this theory.
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Rei Inoue (Chiba University)
Cluster algebra and complex volume of knots (JAPANESE)
Rei Inoue (Chiba University)
Cluster algebra and complex volume of knots (JAPANESE)
[ Abstract ]
The cluster algebra was introduced by Fomin and Zelevinsky around
2000. The characteristic operation in the algebra called `mutation' is
related to various notions in mathematics and mathematical physics. In
this talk I review a basics of the cluster algebra, and introduce its
application to study the complex volume of knot complements in S^3.
Here a mutation corresponds to an ideal tetrahedron.
This talk is based on joint work with Kazuhiro Hikami (Kyushu University).
The cluster algebra was introduced by Fomin and Zelevinsky around
2000. The characteristic operation in the algebra called `mutation' is
related to various notions in mathematics and mathematical physics. In
this talk I review a basics of the cluster algebra, and introduce its
application to study the complex volume of knot complements in S^3.
Here a mutation corresponds to an ideal tetrahedron.
This talk is based on joint work with Kazuhiro Hikami (Kyushu University).
Lie Groups and Representation Theory
17:00-18:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Benjamin Harris (Louisiana State University (USA))
Representation Theory and Microlocal Analysis (ENGLISH)
Benjamin Harris (Louisiana State University (USA))
Representation Theory and Microlocal Analysis (ENGLISH)
[ Abstract ]
Suppose $H\\subset K$ are compact, connected Lie groups, and suppose $\\tau$ is an irreducible, unitary representation of $H$. In 1979, Kashiwara and Vergne proved a simple asymptotic formula for the decomposition of $Ind_H^K\\tau$ by microlocally studying the regularity of vectors in this representation, thought of as vector valued functions on $K$. In 1998, Kobayashi proved a powerful criterion for the discrete decomposability of an irreducible, unitary representation $\\pi$ of a reductive Lie group $G$ when restricted to a reductive subgroup $H$. One of his key ideas was to restrict $\\pi$ to a representation of a maximal compact subgroup $K\\subset G$, view $\\pi$ as a subrepresentation of $L^2(K)$, and then use ideas similar to those developed by Kashiwara and Vergne.
In a recent preprint the speaker wrote with Hongyu He and Gestur Olafsson, the authors consider the possibility of studying induction and restriction to a reductive Lie group $G$ by microlocally studying the regularity of the matrix coefficients of (possibly reducible) unitary representations of $G$, viewed as continuous functions on the (possibly noncompact) Lie group $G$. In this talk, we will outline the main results of this paper and give additional conjectures.
Suppose $H\\subset K$ are compact, connected Lie groups, and suppose $\\tau$ is an irreducible, unitary representation of $H$. In 1979, Kashiwara and Vergne proved a simple asymptotic formula for the decomposition of $Ind_H^K\\tau$ by microlocally studying the regularity of vectors in this representation, thought of as vector valued functions on $K$. In 1998, Kobayashi proved a powerful criterion for the discrete decomposability of an irreducible, unitary representation $\\pi$ of a reductive Lie group $G$ when restricted to a reductive subgroup $H$. One of his key ideas was to restrict $\\pi$ to a representation of a maximal compact subgroup $K\\subset G$, view $\\pi$ as a subrepresentation of $L^2(K)$, and then use ideas similar to those developed by Kashiwara and Vergne.
In a recent preprint the speaker wrote with Hongyu He and Gestur Olafsson, the authors consider the possibility of studying induction and restriction to a reductive Lie group $G$ by microlocally studying the regularity of the matrix coefficients of (possibly reducible) unitary representations of $G$, viewed as continuous functions on the (possibly noncompact) Lie group $G$. In this talk, we will outline the main results of this paper and give additional conjectures.
2013/10/18
PDE Real Analysis Seminar
10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)
Björn Gustavsson (KTH Royal Institute of Technology)
Some applications of partial balayage (ENGLISH)
Björn Gustavsson (KTH Royal Institute of Technology)
Some applications of partial balayage (ENGLISH)
[ Abstract ]
Partial balayage is a rather recent tool in potential theory. One of its origins is the construction of quadrature domains for subharmonic functions by Makoto Sakai in the 1970's. It also gives a convenient way of describing weak solutions to a moving boundary problem for Hele-Shaw flow (Laplacian growth), and recently Stephen Gardiner and Tomas Sjödin have used partial balayage to make progress on an inverse problem in potential theory. I plan to discuss some of these, and related, matters.
Partial balayage is a rather recent tool in potential theory. One of its origins is the construction of quadrature domains for subharmonic functions by Makoto Sakai in the 1970's. It also gives a convenient way of describing weak solutions to a moving boundary problem for Hele-Shaw flow (Laplacian growth), and recently Stephen Gardiner and Tomas Sjödin have used partial balayage to make progress on an inverse problem in potential theory. I plan to discuss some of these, and related, matters.
2013/10/17
GCOE Seminars
16:00-17:00 Room #470 (Graduate School of Math. Sci. Bldg.)
Fikret Goelgeleyen (Bulent Ecevit University)
Stability for Inverse problems for Ultrahyperbolic Equations (ENGLISH)
Fikret Goelgeleyen (Bulent Ecevit University)
Stability for Inverse problems for Ultrahyperbolic Equations (ENGLISH)
[ Abstract ]
In this work, we consider inverse problems of determining a coefficient or a source term in an ultrahyperbolic equation by some lateral boundary data.
We prove Hoelder estimates which are global and local and the key is Carleman estimates.
In this work, we consider inverse problems of determining a coefficient or a source term in an ultrahyperbolic equation by some lateral boundary data.
We prove Hoelder estimates which are global and local and the key is Carleman estimates.
GCOE Seminars
17:00-18:00 Room #470 (Graduate School of Math. Sci. Bldg.)
kazufumi Ito (North Carolina State University)
Fluid-structure interaction model and Levelset method (ENGLISH)
kazufumi Ito (North Carolina State University)
Fluid-structure interaction model and Levelset method (ENGLISH)
[ Abstract ]
We derive a weak form and weak solution of the level set formulation of Cottet and Maitre for fluid-structure interaction problems with immersed surfaces. The method in particular exhibits appealing mass and energy conservation properties and a variational formulation of Peskin’s Immersed Boundary methods.
We derive a weak form and weak solution of the level set formulation of Cottet and Maitre for fluid-structure interaction problems with immersed surfaces. The method in particular exhibits appealing mass and energy conservation properties and a variational formulation of Peskin’s Immersed Boundary methods.
2013/10/16
Number Theory Seminar
17:30-18:30 Room #056 (Graduate School of Math. Sci. Bldg.)
Peter Scholze (Universität Bonn)
Shimura varieties with infinite level, and torsion in the cohomology of locally symmetric spaces (ENGLISH)
Peter Scholze (Universität Bonn)
Shimura varieties with infinite level, and torsion in the cohomology of locally symmetric spaces (ENGLISH)
[ Abstract ]
We will discuss the p-adic geometry of Shimura varieties with infinite level at p: They are perfectoid spaces, and there is a new period map defined at infinite level. As an application, we will discuss some results on torsion in the cohomology of locally symmetric spaces, and in particular the existence of Galois representations in this setup.
We will discuss the p-adic geometry of Shimura varieties with infinite level at p: They are perfectoid spaces, and there is a new period map defined at infinite level. As an application, we will discuss some results on torsion in the cohomology of locally symmetric spaces, and in particular the existence of Galois representations in this setup.
Operator Algebra Seminars
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Yusuke Isono (Univ. Tokyo)
Some prime factorization results for free quantum group factors (JAPANESE)
Yusuke Isono (Univ. Tokyo)
Some prime factorization results for free quantum group factors (JAPANESE)
Seminar on Probability and Statistics
13:30-14:40 Room #052 (Graduate School of Math. Sci. Bldg.)
NAKATANI, Tomoaki (Hokkaido University)
統計解析環境Rにおける多変量GARCHモデルの推定とパッケージ化 (JAPANESE)
[ Reference URL ]
http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/03.html
NAKATANI, Tomoaki (Hokkaido University)
統計解析環境Rにおける多変量GARCHモデルの推定とパッケージ化 (JAPANESE)
[ Reference URL ]
http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/03.html
2013/10/15
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Masamichi Takase (Seikei University)
Desingularizing special generic maps (JAPANESE)
Masamichi Takase (Seikei University)
Desingularizing special generic maps (JAPANESE)
[ Abstract ]
This is a joint work with Osamu Saeki (IMI, Kyushu University).
A special generic map is a generic map which has only definite
fold as its singularities.
We study the condition for a special generic map from a closed
n-manifold to the p-space (n+1>p), to factor through a codimension
one immersion (or an embedding). In particular, for the cases
where p = 1 and 2 we obtain complete results.
Our techniques are related to Smale-Hirsch theory,
topology of the space of immersions, relation between the space
of topological immersions and that of smooth immersions,
sphere eversions, differentiable structures of homotopy spheres,
diffeomorphism group of spheres, free group actions on the sphere, etc.
This is a joint work with Osamu Saeki (IMI, Kyushu University).
A special generic map is a generic map which has only definite
fold as its singularities.
We study the condition for a special generic map from a closed
n-manifold to the p-space (n+1>p), to factor through a codimension
one immersion (or an embedding). In particular, for the cases
where p = 1 and 2 we obtain complete results.
Our techniques are related to Smale-Hirsch theory,
topology of the space of immersions, relation between the space
of topological immersions and that of smooth immersions,
sphere eversions, differentiable structures of homotopy spheres,
diffeomorphism group of spheres, free group actions on the sphere, etc.
2013/10/12
Harmonic Analysis Komaba Seminar
13:00-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)
Tomoya Kato (Nagoya University) 13:30-15:00
The global Cauchy problems for nonlinear dispersive equations on modulation spaces
(JAPANESE)
Naoto Kumanogo (Kogakuin University) 15:30-17:00
Path Integrals--Analysis on path space by time-slicing method (JAPANESE)
Tomoya Kato (Nagoya University) 13:30-15:00
The global Cauchy problems for nonlinear dispersive equations on modulation spaces
(JAPANESE)
Naoto Kumanogo (Kogakuin University) 15:30-17:00
Path Integrals--Analysis on path space by time-slicing method (JAPANESE)
2013/10/09
Operator Algebra Seminars
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Pierre Fima (Univ. Paris VII)
Graphs of quantum groups and K-amenability (ENGLISH)
Pierre Fima (Univ. Paris VII)
Graphs of quantum groups and K-amenability (ENGLISH)
GCOE Seminars
16:00-17:00 Room #370 (Graduate School of Math. Sci. Bldg.)
Oleg Emanouilov (Colorado State Univ.)
Determination of the first order terms for elliptic partial differential equations using the partial Cauchy data (ENGLISH)
Oleg Emanouilov (Colorado State Univ.)
Determination of the first order terms for elliptic partial differential equations using the partial Cauchy data (ENGLISH)
[ Abstract ]
In the bounded domain we consider the variant of the Calderon's problem for the second order partial differential equation with unknown first order terms. Under some geometric condition on domain we prove that the coefficients of this equation can be determined from the partial Cauchy data up to the gauge equivalence.
In the bounded domain we consider the variant of the Calderon's problem for the second order partial differential equation with unknown first order terms. Under some geometric condition on domain we prove that the coefficients of this equation can be determined from the partial Cauchy data up to the gauge equivalence.
2013/10/08
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Tatsuro Shimizu (The Univesity of Tokyo)
An invariant of rational homology 3-spheres via vector fields. (JAPANESE)
Tatsuro Shimizu (The Univesity of Tokyo)
An invariant of rational homology 3-spheres via vector fields. (JAPANESE)
[ Abstract ]
In this talk, we define an invariant of rational homology 3-spheres with
values in a space $\\mathcal A(\\emptyset)$ of Jacobi diagrams by using
vector fields.
The construction of our invariant is a generalization of both that of
the Kontsevich-Kuperberg-Thurston invariant $z^{KKT}$
and that of Fukaya and Watanabe's Morse homotopy invariant $z^{FW}$.
As an application of our invariant, we prove that $z^{KKT}=z^{FW}$ for
integral homology 3-spheres.
In this talk, we define an invariant of rational homology 3-spheres with
values in a space $\\mathcal A(\\emptyset)$ of Jacobi diagrams by using
vector fields.
The construction of our invariant is a generalization of both that of
the Kontsevich-Kuperberg-Thurston invariant $z^{KKT}$
and that of Fukaya and Watanabe's Morse homotopy invariant $z^{FW}$.
As an application of our invariant, we prove that $z^{KKT}=z^{FW}$ for
integral homology 3-spheres.
2013/10/07
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Shin Kikuta (Sophia University)
The limits on boundary of orbifold Kähler-Einstein metrics and orbifold Kähler-Ricci flows over quasi-projective manifolds (JAPANESE)
Shin Kikuta (Sophia University)
The limits on boundary of orbifold Kähler-Einstein metrics and orbifold Kähler-Ricci flows over quasi-projective manifolds (JAPANESE)
[ Abstract ]
In this talk, we consider a sequence of orbifold Kähler-Einstein metrics of negative Ricci curvature or corresponding orbifold normalized Kähler-Ricci flows on a quasi-projective manifold with ample log-canonical bundle for a simple normal crossing divisor. Tian-Yau, S. Bando and H. Tsuji established that the sequence of orbifold Kähler-Einstein metrics converged to the complete Käler-Einstein metric of negative Ricci curvature on the complement of the boundary divisor. The main purpose of this talk is to show that such a convergence is also true on the boundary for both of the orbifold Kähler-Einstein metrics and the orbifold normalized Kähler-Ricci flows.
In this talk, we consider a sequence of orbifold Kähler-Einstein metrics of negative Ricci curvature or corresponding orbifold normalized Kähler-Ricci flows on a quasi-projective manifold with ample log-canonical bundle for a simple normal crossing divisor. Tian-Yau, S. Bando and H. Tsuji established that the sequence of orbifold Kähler-Einstein metrics converged to the complete Käler-Einstein metric of negative Ricci curvature on the complement of the boundary divisor. The main purpose of this talk is to show that such a convergence is also true on the boundary for both of the orbifold Kähler-Einstein metrics and the orbifold normalized Kähler-Ricci flows.
2013/10/03
Geometry Colloquium
10:00-11:30 Room #122 (Graduate School of Math. Sci. Bldg.)
Masayuki ASAOKA (Kyoto University)
A rigidity lemma for cocycles over BS(1,k)-actions (JAPANESE)
Masayuki ASAOKA (Kyoto University)
A rigidity lemma for cocycles over BS(1,k)-actions (JAPANESE)
[ Abstract ]
Existence of an invariant geometric structure is persistent for many known examples of group actions on homogeneous spaces. In this talk, I would like to report an attempt to explain such a rigidity from a unified point of view. We will see that some rigidity results are reduced to a rigidity lemma on Diff(R^n,0)-valued cocycles over BS(1,k)-actions, where BS(1,k) is the Baumslag-Solitar group.
Existence of an invariant geometric structure is persistent for many known examples of group actions on homogeneous spaces. In this talk, I would like to report an attempt to explain such a rigidity from a unified point of view. We will see that some rigidity results are reduced to a rigidity lemma on Diff(R^n,0)-valued cocycles over BS(1,k)-actions, where BS(1,k) is the Baumslag-Solitar group
2013/10/02
Operator Algebra Seminars
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Koichi Shimada (Univ. Tokyo)
A classification of flows on AFD factors with faithful Connes-Takesaki modules
(JAPANESE)
Koichi Shimada (Univ. Tokyo)
A classification of flows on AFD factors with faithful Connes-Takesaki modules
(JAPANESE)
2013/10/01
Tuesday Seminar on Topology
16:30-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Naoyuki Monden (Tokyo University of Science)
The geography problem of Lefschetz fibrations (JAPANESE)
Naoyuki Monden (Tokyo University of Science)
The geography problem of Lefschetz fibrations (JAPANESE)
[ Abstract ]
To consider holomorphic fibrations complex surfaces over complex curves
and Lefschetz fibrations over surfaces is one method for the study of
complex surfaces of general type and symplectic 4-manifods, respectively.
In this talk, by comparing the geography problem of relatively minimal
holomorphic fibrations with that of relatively minimal Lefschetz
fibrations (i.e., the characterization of pairs $(x,y)$ of certain
invariants $x$ and $y$ corresponding to relatively minimal holomorphic
fibrations and relatively minimal Lefschetz fibrations), we observe the
difference between complex surfaces of general type and symplectic
4-manifolds. In particular, we construct Lefschetz fibrations violating
the ``slope inequality" which holds for any relatively minimal holomorphic
fibrations.
To consider holomorphic fibrations complex surfaces over complex curves
and Lefschetz fibrations over surfaces is one method for the study of
complex surfaces of general type and symplectic 4-manifods, respectively.
In this talk, by comparing the geography problem of relatively minimal
holomorphic fibrations with that of relatively minimal Lefschetz
fibrations (i.e., the characterization of pairs $(x,y)$ of certain
invariants $x$ and $y$ corresponding to relatively minimal holomorphic
fibrations and relatively minimal Lefschetz fibrations), we observe the
difference between complex surfaces of general type and symplectic
4-manifolds. In particular, we construct Lefschetz fibrations violating
the ``slope inequality" which holds for any relatively minimal holomorphic
fibrations.
2013/09/10
Monthly Seminar on Arithmetic of Automorphic Forms
13:30-15:00 Room #123 (Graduate School of Math. Sci. Bldg.)
Yuval Flicker (Ohio State Univ.) 13:30-15:00
Counting automorphic representations (JAPANESE)
Yuval Flicker (Ohio State University) 13:30-15:00
Counting automorphic representations II (Sept. 17) (JAPANESE)
Yuval Flicker (Ohio State Univ.) 13:30-15:00
Counting automorphic representations (JAPANESE)
Yuval Flicker (Ohio State University) 13:30-15:00
Counting automorphic representations II (Sept. 17) (JAPANESE)
2013/09/07
FMSP Lectures
15:00-16:30 Room #123 (Graduate School of Math. Sci. Bldg.)
Bertrand Deroin (University of Paris-Sud)
Dominating representations by Fuchsian ones (ENGLISH)
Bertrand Deroin (University of Paris-Sud)
Dominating representations by Fuchsian ones (ENGLISH)
[ Abstract ]
We will focus on the problem of dominating the translation lengths of a representation from a surface group to the isometries of a CAT(-1) space by the lengths induced by a hyperbolic structure on the surface. This is related to the construction of 3-dimensional anti-de-Sitter compact manifolds. This is a collaboration with Nicolas Tholozan.
We will focus on the problem of dominating the translation lengths of a representation from a surface group to the isometries of a CAT(-1) space by the lengths induced by a hyperbolic structure on the surface. This is related to the construction of 3-dimensional anti-de-Sitter compact manifolds. This is a collaboration with Nicolas Tholozan.
2013/08/12
Operator Algebra Seminars
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Roberto Longo (Univ. Roma, Tor Vergata)
Operator Algebraic Construction of Quantum Field Theory Models (ENGLISH)
Roberto Longo (Univ. Roma, Tor Vergata)
Operator Algebraic Construction of Quantum Field Theory Models (ENGLISH)
FMSP Lectures
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Roberto Longo (Univ. Roma, Tor Vergata)
Operator Algebraic Construction of Quantum Field Theory Models (ENGLISH)
Roberto Longo (Univ. Roma, Tor Vergata)
Operator Algebraic Construction of Quantum Field Theory Models (ENGLISH)
2013/08/09
Operator Algebra Seminars
16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)
Tullio Ceccherini-Silberstein (Univ. Sannio)
Cellular automata and groups (ENGLISH)
Tullio Ceccherini-Silberstein (Univ. Sannio)
Cellular automata and groups (ENGLISH)
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