## Seminar information archive

### 2010/07/20

#### Tuesday Seminar on Topology

17:00-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
Keiko Kawamuro (University of Iowa)
A polynomial invariant of pseudo-Anosov maps (JAPANESE)
[ Abstract ]
Thurston-Nielsen classified surface homomorphism into three classes. Among them, the pseudo-Anosov class is the most interesting since there is strong connection to the hyperbolic manifolds. As an invariant, the dilatation number has been known. In this talk, I will introduce a new invariant of pseudo-Anosov maps. It is an integer coefficient polynomial, which contains the dilatation as the largest real root and is often reducible. I will show properties of the polynomials, examples, and some application to knot theory. (This is a joint work with Joan Birman and Peter Brinkmann.)

### 2010/07/15

#### Lie Groups and Representation Theory

14:30-16:00   Room #122 (Graduate School of Math. Sci. Bldg.)
Soo Teck Lee (Singapore National University)
Pieri rule and Pieri algebras for the orthogonal groups (ENGLISH)

#### Operator Algebra Seminars

16:30-18:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Narutaka Ozawa (Univ. Tokyo)
Type II$_1$ von Neumann representations for Hecke operators on Maass forms (after F. Radulescu) (ENGLISH)

#### Seminar on Probability and Statistics

15:00-16:10   Room #000 (Graduate School of Math. Sci. Bldg.)
MASUDA, Hiroki (Graduate School of Mathematics, Kyushu University)
Mighty convergence in LAD type estimation (JAPANESE)
[ Abstract ]
We propose a LAD (least absolute deviation) type contrast function for estimating Levy driven Ornstein-Uhlenbeck processes sampled at high frequency. The asymptotic behavior and polynomial-type large deviation inequality concerning the statistical random fields in question are derived, entailing an asymptotic normality and convergence of moments of the LAD estimator. Also, we will mention some numerical experiments done by the R software and some possible extensions of the framework.
[ Reference URL ]
http://www.ms.u-tokyo.ac.jp/~kengok/statseminar/2010/04.html

### 2010/07/13

#### Tuesday Seminar on Topology

16:30-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
Marion Moore (University of California, Davis)
High Distance Knots in closed 3-manifolds (ENGLISH)
[ Abstract ]
Let M be a closed 3-manifold with a given Heegaard splitting.
We show that after a single stabilization, some core of the
stabilized splitting has arbitrarily high distance with respect
to the splitting surface. This generalizes a result of Minsky,
Moriah, and Schleimer for knots in S^3. We also show that in the
complex of curves, handlebody sets are either coarsely distinct
or identical. We define the coarse mapping class group of a
Heeegaard splitting, and show that if (S,V,W) is a Heegaard
splitting of genus greater than or equal to 2, then the coarse
mapping class group of (S,V,W) is isomorphic to the mapping class
group of (S, V, W). This is joint work with Matt Rathbun.

#### Tuesday Seminar of Analysis

17:00-18:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Carlos Villegas Blas (Universidad Nacional Autonoma de Mexico)
On a limiting eigenvalue distribution theorem for perturbations of the hydrogen atom (JAPANESE)
[ Abstract ]
Let H be the hydrogen atom Hamiltonian. We will show that
the operator H+P can have well defined clusters of eigenvalues
for a suitable perturbation P=f(h)Q where Q is a pseudo-differential
operator of order zero and f(h) is a small quantity depending of
the Planck's parameter h. We will show that the distribution of
eigenvalues in those clusters has a semi-classical limit involving
the averages of the principal symbol of Q along the classical orbits
of the Kepler problem.

### 2010/07/12

#### Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Yu KAWAKAMI (Kyushu Univ.)
The value distribution of the Gauss map of wave fronts and its applications (JAPANESE)

#### Algebraic Geometry Seminar

16:40-18:10   Room #126 (Graduate School of Math. Sci. Bldg.)
Ryo Ohkawa (Tokyo Institute of Technology)
Flips of moduli of stable torsion free sheaves with $c_1=1$ on
$\\mathbb{P}^2$ (JAPANESE)
[ Abstract ]
We study flips of moduli schemes of stable torsion free sheaves
on the projective plane via wall-crossing phenomena of Bridgeland stability.
They are described as stratified Grassmann bundles by variation of
stability of modules over certain finite dimensional algebra.

### 2010/07/08

#### Applied Analysis

16:00-17:30   Room #002 (Graduate School of Math. Sci. Bldg.)
Anna Vainchtein (University of Pittsburgh, Department of Mathematics)
Effect of nonlinearity on the steady motion of a twinning dislocation (ENGLISH)
[ Abstract ]
We consider the steady motion of a twinning dislocation in a Frenkel-Kontorova lattice with a double-well substrate potential that has a non-degenerate spinodal region. Semi-analytical traveling wave solutions are constructed for the piecewise quadratic potential, and their stability and further effects of nonlinearity are investigated numerically. We show that the width of the spinodal region and the nonlinearity of the potential have a significant effect on the dislocation kinetics, resulting in stable steady motion in some low-velocity intervals and lower propagation stress. We also conjecture that a stable steady propagation must correspond to an increasing portion of the kinetic relation between the applied stress and dislocation velocity.

#### Operator Algebra Seminars

16:30-18:00   Room #122 (Graduate School of Math. Sci. Bldg.)
Dave Penneys (UC Berkeley)
Killing weeds with annular multiplicities $*10$ via quadratic tangles (ENGLISH)
[ Abstract ]
In recent work with Morrison, Peters, and Snyder, we eliminate two
families of possible principal graphs with graph norms less than 5 using
techniques derived from Jones' work on quadratic tangles.

### 2010/07/07

#### Seminar on Mathematics for various disciplines

10:30-11:30   Room #056 (Graduate School of Math. Sci. Bldg.)
Masahide Sato (Information Media Center, Kanazawa University)
Instabilities of steps on a vicinal face induced by the
asymmetry of diffusion field. (JAPANESE)

#### GCOE Seminars

17:00-18:00   Room #002 (Graduate School of Math. Sci. Bldg.)

[ Abstract ]

[ Reference URL ]
http://www.infsup.jp/utnas/

#### Numerical Analysis Seminar

17:00-18:00   Room #002 (Graduate School of Math. Sci. Bldg.)
Kaname Amano (Ehime University)
Numerical conformal mappings of multiply connected domains by the charge simulation method (JAPANESE)
[ Reference URL ]
http://www.infsup.jp/utnas/

#### Number Theory Seminar

16:30-17:30   Room #056 (Graduate School of Math. Sci. Bldg.)
Takahiro Tsushima (University of Tokyo)
On the stable reduction of $X_0(p^4)$ (JAPANESE)

### 2010/07/06

#### Tuesday Seminar on Topology

17:00-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
Akira Kono (Kyoto University)
On the cohomology of free and twisted loop spaces (JAPANESE)
[ Abstract ]
A natural extension of cohomology suspension to a free loop space is
constructed from the evaluation map and is shown to have a good
properties in cohomology calculation. This map is generalized to a
twisted loop space.
As an application, the cohomology of free and twisted loop space of
classifying spaces of compact Lie groups, including certain finite
Chevalley groups is calculated.

#### Operator Algebra Seminars

16:30-18:00   Room #118 (Graduate School of Math. Sci. Bldg.)
Robert Sims (Univ. Arizona)
On the Existence of the Dynamics for Anharmonic Quantum Oscillator Systems (ENGLISH)

### 2010/07/05

#### Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Shin-ichi MATSUMURA (Univ. of Tokyo)
Expression of restricted volumes with current integration (JAPANESE)

#### Algebraic Geometry Seminar

16:40-18:10   Room #126 (Graduate School of Math. Sci. Bldg.)
Katsuhisa Furukawa (Waseda University)
Rational curves on hypersurfaces (JAPANESE)
[ Abstract ]
Our purpose is to study the family of smooth rational curves of degree $e$ lying on a hypersurface of degree $d$ in $\\mathbb{P}^n$, and to investigate properties of this family (e.g., dimension, smoothness, connectedness).
Our starting point is the research about the family of lines (i.e., $e = 1$), which was studied by W. Barth and A. Van de Ven over $\\mathbb{C}$, and by J. Koll\\'{a}r over an algebraically closed field of arbitrary characteristic.
For the degree $e > 1$, the family of rational curves was studied by J. Harris, M. Roth, and J. Starr over $\\mathbb{C}$ in the case of $d < (n+1)/2$.
In this talk, we study the family of rational curves in arbitrary characteristic under the assumption $e = 2,3$ and $d > 1$, or $e > 3$ and $d > 2e-4$.

### 2010/07/02

#### Colloquium

16:30-17:30   Room #123 (Graduate School of Math. Sci. Bldg.)
Mitsuhiro Shishikura (Kyoto University)
Hausdorff dimension and measure of conformal fractals (JAPANESE)

### 2010/06/29

#### Tuesday Seminar on Topology

16:30-18:00   Room #056 (Graduate School of Math. Sci. Bldg.)
Takahiro Kitayama (The University of Tokyo)
Non-commutative Reidemeister torsion and Morse-Novikov theory (JAPANESE)
[ Abstract ]
For a circle-valued Morse function of a closed oriented manifold, we
show that Reidemeister torsion over a non-commutative formal Laurent
polynomial ring equals the product of a certain non-commutative
Lefschetz-type zeta function and the algebraic torsion of the Novikov
complex over the ring. This gives a generalization of the results of
Hutchings-Lee and Pazhitnov on abelian coefficients. As a consequence we
obtain Morse theoretical and dynamical descriptions of the higher-order
Alexander polynomials.

### 2010/06/28

#### Seminar on Geometric Complex Analysis

10:30-12:00   Room #128 (Graduate School of Math. Sci. Bldg.)
Kengo HIRACHI (Univ. of Tokyo)
Total Q-curvature vanishes on integrable CR manifolds (ENGLISH)

### 2010/06/26

#### GCOE lecture series

13:50-14:50   Room #056 (Graduate School of Math. Sci. Bldg.)
Feng Xu (UC Riverside)
On a subfactor generalization of Wall's conjecture (ENGLISH)

#### Lectures

10:00-16:10   Room #056 (Graduate School of Math. Sci. Bldg.)
Yoshimichi Ueda (Kyushu Univ.) 10:00-11:00
On the predual of non-commutative $H^\\infty$ (ENGLISH)
Hiroki Matui (Chiba Univ.) 11:20-12:20
${\\mathbf Z}^N$-actions on UHF algebras of infinite type (ENGLISH)
Feng Xu (UC Riverside) 13:50-14:50
On a subfactor generalization of Wall's conjecture (ENGLISH)
Masaki Izumi (Kyoto Univ.) 15:10-16:10
Group actions on Kirchberg algebras (ENGLISH)

### 2010/06/25

#### Classical Analysis

16:30-18:00   Room #122 (Graduate School of Math. Sci. Bldg.)
Kazuki Hiroe (University of Tokyo)
Euler transform and Weyl groups of symmetric Kac-Moody Lie algebras (JAPANESE)

#### Lectures

15:00-17:30   Room #056 (Graduate School of Math. Sci. Bldg.)
Narutaka Ozawa (Univ. Tokyo) 15:00-16:00
Quasi-homomorphism rigidity with noncommutative targets (ENGLISH)
Yoshiko Ogata (Univ. Tokyo) 16:30-17:30
Ruelle-Lanford functions for quantum spin systems (ENGLISH)