#
Math Colloquium

**
Math colloquium meets
on Mondays at 12:15 in Schreiber 006,
Tel Aviv University.
**

#
Fall 2006

###
30.10.2006, 12:15
Yehuda Shalom
, Tel Aviv University, Israel
The algebraization of Kazhdan's property (T)

###
13.11.2006, 12:15
Misha Kapovich
, UC Davis, USA
Leonard Blumenthal Lectures in Geometry.

###
Products of matrices.

ABSTRACT: I will discuss some very basic
problems of linear algebra, i.e. how
eigenvalues and singular values of matrices
behave under the addition and multiplication.
I will explain the relation between
these problems and geometry of triangles.
###
20.11.2006, 12:15
Gady Kozma
,Weizmann Institute, Israel
One-dimensional long-range diffusion-limited aggregation.

ABSTRACT: We investigate this model for random self-organizing fractals and
calculate the dimension as a function of the parameters. We shall expose
no less than 3 phase transitions, and try to explain their origin. Joint
work with Gideon Amir, Omer Angel and Itai Benjamini.
###
27.11.2006, 12:15
Paul Biran
,Tel Aviv University, Israel
Symplectic Morse Theory.

###
11.12.2006, 12:15
George Zaslavsky
, Courant Institute, New York, USA
Fractional dynamics for long space-time interactions.

###
18.12.2006, 12:15
Boris Mityagin
, Ohio State University, USA
Instability zones for periodic 1D Schroedinger and Dirac operators.

ABSTRACT: Spectra of the Schroedinger and Dirac operators with periodic potentials on
the real line R have band structure, i.e., the segments of continuous
spectrum
alternate with spectral gaps, or instability zones. The sizes of these
zones decay,
and the rate of that decay depends on the smoothness of the potential. One
can
go to the opposite direction and make conclusion about the smoothness of a
potential by the rate of decay of its instability zones. On the level of
infinitely
differentiable or analytic functions this phenomenon has been understood
in the
case of Schroedinger operators in the 1960~Rs and 70~Rs. However, only
recently the
relationship between the potential smoothness and the rate of decay of
instability
zones became completely understood and analyzed
for broad range of classes of differentiable functions;
for Dirac operators, not only for Hill~Schroedinger operators;
both in the self~adjoint and non~self~adjoint cases.
The talk gives a survey of these results based on the methods developed by
Plamen Djakov and the speaker. Their paper appeared in
Uspehi 61:4 (2006), 77-182. (See English transl. in Russian
Mathematical Surveys.)
###
01.01.2007, 12:15
Alex Furman
, University of Illinois at Chicago, USA
Superrigidity revisited.

ABSTACT: In the talk I will discuss the celebrated superrigidity theorem(s)
of Margulis from the 70s and some of the many more recent
results inspired, motivated and analogous to the original
superrigidity theorems. I will describe a unified approach
to some of these superrigidity phenomena (based on joint
works with Uri Bader).
###
08.01.2007, 12:15
Joseph Bernstein
, Tel Aviv University, Israel
Covexity and subconvexity estimates for triple periods of automorphic functions.

(joint work with Andre Reznikov from Bar Ilan University)
#####
Organizer: Semyon Alesker
, e-mail: semyon AT post DOT tau.ac.il