Seminar information archive
Seminar information archive ~04/30|Today's seminar 05/01 | Future seminars 05/02~
Algebraic Geometry Seminar
Takuzo Okada (Saga University)
On birationally tririgid Q-Fano threefolds (JAPANESE)
I will talk about birational geometry of Q-Fano threefolds. A Mori
fiber space birational to a given Q-Fano threefold is called a birational Mori fiber structure of the threefold. The existence of Q-Fano threefolds with a unique birational Mori fiber structure (resp. with two birational Mori fiber structures) is known. In this talk I will give an example of Q-Fano threefolds with three birational Mori fiber structures and also discuss about the behavior of birational Mori fiber structures in a family.
2013/12/06
Geometry Colloquium
Sadayoshi KOJIMA (Tokyo Institute of Technology)
Normalized entropy versus volume for pseudo-Anosovs (JAPANESE)
We establish an explicit linear inequality between the normalized entropy of pseudo-Anosov automorphisms and the hyperbolic volume of their mapping tori, based on a recent result by Jean-Marc Schlenker on renormalized volume of quasi-Fuchsian
manifolds. This is a joint work with Greg McShane.
FMSP Lectures
Simon Gindikin (Rutgers University)
Horospheres: geometry and analysis (II) (ENGLISH)
About 50 years ago Gelfand suggested a concepion of horospherical transform which, he hoped, must be an universal principle unifying non commutative harmonic analysis. I want to make several historic remarks (especialy, since this year is the centenial anniversary of Gelfand). I want to discuss the evolution of this fundamental conception for 50 years and how Gelfand’s dreams are looked today. I will discuss an elementary case of hyperboloids of any signature where there were not too much progress after old initial result of Gelfand-Graev.
http://fmsp.ms.u-tokyo.ac.jp/FMSPLectures_Gindikin.pdf
Colloquium
Naoki Imai (Graduate School of Mathematical Scinences, The University of Tokyo)
Local Langlands correspondence and Lubin-Tate perfectoid spaces (JAPANESE)
Colloquium
Naoki Imai (Graduate School of Mathematical Sciences, The University of Tokyo)
Local Langlands correspondence and Lubin-Tate perfectoid spaces (JAPANESE)
2013/12/05
Geometry Colloquium
Sumio Yamada (Gakushuin University)
Variational characterizations of exact solutions of the Einstein equation (JAPANESE)
There are a set of well-known exact solutions to the Einstein equation. The most important one is the Schwarzschild metric, and it models a Ricci-flat space-time, which is asymptotically flat. In addition, there are the Reissner-Nordstrom metric and the Majumdar-Papapetrou metric, which satisfy the Einstein-Maxwell equation, instead of the vacuum Einstein equation. In a jointwork with Marcus Khuri and Gilbert Weinstein, it is shown that those metrics are characterized as the equality
cases of a set of so-called Penrose-type inequalities. The method of proof is a
conformal deformation of Riemannian metrics defined on the space-like slice of the space-time.
2013/12/04
Seminar on Probability and Statistics
HINO, Hideitsu (University of Tsukuba)
A quantile-based likelihood estimator for information theoretic clustering (JAPANESE)
[ Reference URL ]
http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/09.html
FMSP Lectures
Simon Gindikin (Rutgers University)
Horospheres: geometry and analysis (I) (ENGLISH)
About 50 years ago Gelfand suggested a concepion of horospherical transform which, he hoped, must be an universal principle unifying non commutative harmonic analysis. I want to make several historic remarks (especialy, since this year is the centenial anniversary of Gelfand). I want to discuss the evolution of this fundamental conception for 50 years and how Gelfand’s dreams are looked today. I will discuss an elementary case of hyperboloids of any signature where there were not too much progress after old initial result of Gelfand-Graev.
http://fmsp.ms.u-tokyo.ac.jp/FMSPLectures_Gindikin.pdf
2013/12/03
Tuesday Seminar on Topology
Bruno Martelli (Univ. di Pisa)
Hyperbolic four-manifolds with one cusp (cancelled) (JAPANESE)
(joint work with A. Kolpakov)
We introduce a simple algorithm which transforms every
four-dimensional cubulation into a cusped finite-volume hyperbolic
four-manifold. Combinatorially distinct cubulations give rise to
topologically distinct manifolds. Using this algorithm we construct
the first examples of finite-volume hyperbolic four-manifolds with one
cusp. More generally, we show that the number of k-cusped hyperbolic
four-manifolds with volume smaller than V grows like C^{V log V} for
any fixed k. As a corollary, we deduce that the 3-torus bounds
geometrically a hyperbolic manifold.
FMSP Lectures
Erwin Bolthausen (University of Zurich)
Random walks in random environments (ENGLISH)
[ Reference URL ]
http://fmsp.ms.u-tokyo.ac.jp/FMSPLectures_Bolthausen.pdf
2013/12/02
Seminar on Geometric Complex Analysis
Anne-Katrin Herbig (Nagoya University)
A smoothing property of the Bergman projection (ENGLISH)
Let $D$ be a bounded domain with smooth boundary in complex space of dimension $n$. Suppose its Bergman projection $B$ maps the Sobolev space of order $k$ continuously into the one of order $m$. Then the following smoothing result holds: the full Sobolev norm of $Bf$ of order $k$ is controlled by $L^2$-derivatives of $f$ taken along a single, distinguished direction (of order up to $m$). This talk is based on joint work with J. D. McNeal and E. J. Straube.
2013/11/29
FMSP Lectures
Erwin Bolthausen (University of Zurich)
Random walks in random environments (ENGLISH)
[ Reference URL ]
http://fmsp.ms.u-tokyo.ac.jp/FMSPLectures_Bolthausen.pdf
FMSP Lectures
Erwin Bolthausen (University of Zurich)
Random walks in random environments (ENGLISH)
[ Reference URL ]
http://fmsp.ms.u-tokyo.ac.jp/FMSPLectures_Bolthausen.pdf
2013/11/28
Geometry Colloquium
Shinichiroh MATSUO (Osaka University)
The prescribed scalar curvature problem for metrics with unit total volume (JAPANESE)
In this talk I will talk about the modified Kazdan-Warner problem.
Kazdan and Warner in 1970's completely solved the prescribed scalar curvature problem. In particular, they proved that every function on a manifold with positive Yamabe invariant is the scalar curvature of some metric. Kobayashi in 1987 proposed the modified problem of finding metrics with prescribed scalar curvature and total volume 1. He proved that every function except positive constants on a manifold with positive Yamabe invariant is the scalar curvature of some metricwith total volume 1.
I have recently settled the remaining case. Applying Taubes tequniques to the scalar curvature equations, we can glue two Yamabe metrics to construct metrics with very large scalar curvature and unit total volume, and prove that every positive constant is the scalar curvature of some metric with total volume 1.
GCOE Seminars
Oleg Emanouilov (Colorado State Univ.)
Inverse problem for the Maxwell equations (ENGLISH)
We consider an analog of Caderon's problem for the system of Maxwell equations in a cylindrical domain.
Under some geometrical assumptions on domain we show that from the partial data one can recover the complete set of parameters.
2013/11/27
Seminar on Probability and Statistics
TAKEUCHI, Atsushi (Osaka City University)
Density of solutions to stochastic functional differential equations (JAPANESE)
[ Reference URL ]
http://www.sigmath.es.osaka-u.ac.jp/~kamatani/statseminar/2013/08.html
2013/11/26
Tuesday Seminar on Topology
Hiroo Tokunaga (Tokyo Metropolitan University)
Rational elliptic surfaces and certain line-conic arrangements (JAPANESE)
Let S be a rational elliptic surface. The generic
fiber of S can be considered as an elliptic curve over
the rational function field of one variable. We can make
use of its group structure in order to cook up a curve C_2 on
S from a given section C_1.
In this talk, we consider certain line-conic arrangements of
degree 7 based on this method.
Seminar on Mathematics for various disciplines
Huaxiong Huang (York University)
An immersed boundary method for mass transfer across permeable moving interfaces (ENGLISH)
In this talk, we present an immersed boundary method for mass transfer across permeable deformable moving interfaces interacting with the surrounding fluids. One of the key features of our method is the introduction of the mass flux as an independent variable, governed by a non-standard vector transport equation. The flux equation, coupled with the mass transport and the fluid flow equations, allows for a natural implementation of an immersed boundary algorithm when the flux across the interfaces is proportional to the jump in concentration. As an example, the oxygen transfer from red blood cells in a capillary to its wall is used to illustrate the applicability of the proposed method. We show that our method is capable of handling multi-physics problems involving fluid- structure interaction with multiple deformable moving interfaces and (interfacial) mass transfer simultaneously.
This is joint work with X. Gong and Z. Gong.
Tuesday Seminar of Analysis
Haruya MIZUTANI (Gakushuin University)
Global Strichartz estimates for Schr\\"odinger equations with long range metrics (JAPANESE)
We consider Schr\\"odinger equations on the asymptotically Euclidean space
with the long-range condition on the metric.
We show that if the high energy resolvent has at most polynomial growth with respect to the energy,
then global-in-time Strichartz estimates, outside a large compact set, hold.
Under the non-trapping condition we also discuss global-in-space Strichartz estimates.
This talk is based on a joint work with J.-M. Bouclet (Toulouse University).
2013/11/25
Seminar on Geometric Complex Analysis
Kota Hattori (The University of Tokyo)
On hyperkaehler metrics on holomorphic cotangent bundles on complex reductive Lie groups (JAPANESE)
There exists a complete hyperkaehler metric on the holomorphic cotangent bundle on each complex reductive Lie group. It was constructed by Kronheimer, using hyperkaehler quotient method. In this talk I explain how to describe the Kaehler potentials of these metrics.
Algebraic Geometry Seminar
Takayuki Koike (The University of Tokyo)
Minimal singular metrics of some line bundles with infinitely generated section rings (JAPANESE)
We consider Hermitian metrics of pseudo-effective line bundles on smooth
projective varieties defined over $\\mathbb{C}$.
Especially we are interested in (possibly singular) Hermitian metrics
with semi-positive curvatures when the section rings are not finitely generated.
We study where and how minimal singular metrics, special Hermitian
metrics with semi-positive curvatures, diverges in the following two situations;
a line bundle admitting no Zariski decomposition even after any
modifications (Nakayama example)
and a nef line bundle $L$ on $X$ satisfying $D \\subset |mL|$ and $|mL-D|
= \\emptyset$ for some divisor $D \\subset X$ and for all $m \\geq 1$ (
Zariski example).
2013/11/22
FMSP Lectures
Alfred RAMANI (École polytechnique)
Integrable discrete systems, an introduction Pt. 2 (ENGLISH)
The second part will mostly be devoted to the various integrability detectors (singularity confinement, algebraic entropy) for integrability of discrete systems, in one or more dimensions. The most important systems identified through these detectors, namely the discrete Painlev¥'e equations, will be presented in detail, through a geometric approach.
2013/11/21
GCOE Seminars
Florin Ambro (IMAR)
Cyclic covers and toroidal embeddings (ENGLISH)
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/documents/miniworkshop.pdf
2013/11/20
Number Theory Seminar
Valentina Di Proietto (The University of Tokyo)
On the homotopy exact sequence for the logarithmic de Rham fundamental group (ENGLISH)
Let K be a field of characteristic 0 and let X* be a quasi-projective simple normal crossing log variety over the log point K* associated to K. We construct a log de Rham version of the homotopy sequence \\pi_1(X*/K*)-->\\pi_1(X*/K)--\\pi_1(K*/K)-->1 and prove that it is exact. Moreover we show the injectivity of the first map for certain quotients of the groups. Our proofs are purely algebraic. This is a joint work with A. Shiho.
Operator Algebra Seminars
Camille Male (Univ. Paris VII)
The spectrum of large random matrices, the non commutative random variables and the distribution of traffics (ENGLISH)
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