[Vortraege] Vortragsankündigungen der komm. Woche (KW 46)

Fri Nov 7 13:42:10 CET 2008

Sehr geehrte Fakultätsmitglieder,

anbei die Vortragsankündigungen für die nächste Woche, im Anhang finden 
Sie den Text auch als PDF Datei.

Montag,  10. November, 10:30 Uhr bis 11:30 Uhr, 2A180, UZA 2
Junior Kolloquium
Prof. Dr. Maxime Kontsevitch (Institut des Hautes Ètudes Scientifiques, 
Bures-sur-yvette, France)
„Introduction to Donaldson Thomas Invariants“
Abstract: In this talk we will give a brief explanation of Donaldson 
Thomas theory on examples.

Mathematisches Kolloquium
15:00 Uhr bis 16:00 Uhr, C 209, UZA 4
Univ.-Prof. Dr. Ludmil Katzarkov (Universität Wien, Fakultät für Mathematik)
„Birational Geometry old and new“
Abstract: We will explain some classical problems in Algebraic Geometry 
and new ways to look at them.

16:00 Uhr: K & K im Common Room

16:30 Uhr bis 17:30 Uhr, C 209, UZA 4
Prof. Dr. Maxime Kontsevitch (Institut des Hautes Ètudes Scientifiques, 
Bures-sur-yvette, France)
„Affine Structures and Mirror Symmetry”
Abstract: In this talk we will describe geometry of Mirror Symmetry in 
terms of integral affine structures, and make links with complex 
algebraic integrable systems and Donaldson Thomas invariants.

Anschließend Buffet im Common Room.

(Dekan Univ.-Prof. Dr. Harald Rindler, Univ.-Prof. Dr. Ludmil Katzarkov)

Montag, 10. November bis Freitag, 14. November, ESI Boltzmann Lecture Hall,
Boltzmanngasse 9, 1090 Wien
ESI Workshop on Structural Probability
The workshop Structural Probability is a continuation of a series of 
earlier programmes at ESI: the special semester Random Walks in 2001, 
the RDSES/ESI Educational Workshop on Discrete Probability in 2006, and 
the programme on Algebraic, geometric and probabilistic aspects of 
amenability in 2007.
This workshop is intended to bring together people from several areas of 
probability in which the role of structural properties (algebraic, 
geometrical or combinatorial) of the underlying spaces is especially 
important: random walks, percolation, dimer models and lattice systems.
Week 2
November 10th to November 14th , 2008
Bezüglich Programm (inkl. Beginn/Ende) für die 2. Woche (10.-14.11.2008) 
kontaktieren Sie bitte das Erwin Schrödinger Institut (ESI): 
+43-1-4277-28282, +43-1-4277-28299 (Fax), secr at esi.ac.at 
Organized by Prof. Vadim Kaimanovich and Prof. Klaus Schmidt
For further information contact the organizers V. Kaimanovich and K. 
Schmidt at aesi at esi.ac.at,
http://www.mat.univie.ac.at/~kschmidt/probability.html

Montag,  10. November, 16:00 Uhr, D 107
Geometry Seminar
Prof. Dr. Roland G. Fryer (Department of Economics, Harvard University)
„Measuring the Compactness of Political Districting Plans”
Abstract: The United States Supreme Court has long recognized 
compactness as an important principle in assessing the constitutionality 
of political districting plans. We propose a measure of compactness 
based on the distance between voters within the same district relative 
to the minimum distance achievable which we coin the relative proximity 
index. We prove that any compactness measure which satisfies three 
desirable properties (anonymity of voters, efficient clustering, and 
invariance to scale, population density, and number of districts) ranks 
districting plans identically to our index. We then calculate the 
relative proximity index for the 106th Congress, requiring us to solve 
for each state's maximal compactness; an NP-hard problem. Using two 
properties of maximally compact districts, we prove they are power 
diagrams and develop an algorithm based on these insights. The 
correlation between our index and the commonly-used measures of 
dispersion and perimeter is -.37 and -.29, respectively. We conclude by 
estimating seat-vote curves under maximally compact districts for 
several large states. The fraction of additional seats a party obtains 
when their average vote increases is significantly greater under 
maximally compact districting plans, relative to the existing plans.

Dienstag, 11. November, 11:15 Uhr bis 12:45 Uhr, 2A180, UZA 2
Complex Analysis Seminar
Dr. Jean Ruppenthal (University of Wuppertal)
„Hartogs' extension theorem on (n-1)-complete complex spaces”
Abstract: Whereas first versions of Hartogs' extension theorem (e.g. on 
polydiscs) were usually obtained by filling Hartogs' figures with 
holomorphic discs, no such geometrical proof was known for the general 
theorem in complex number space for a long time. Proofs of the general 
theorem in C^n usually depend on the Bochner-Martinelli-Koppelman 
formula or on the solution of the d-bar-equation with compact support 
(the famous idea due to Ehrenpreis). Only recently, Joel Merker and 
Egmont Porten were able to fill the gap by giving a geometrical proof of 
Hartogs' extension theorem in C^n by using a finite number of 
parameterized families of holomorphic discs and Morse-theoretical tools 
for the global topological control of monodromy, but no d-bar-theory or 
intergal kernels (except the Cauchy kernel). They also extended their 
result to the general case of (n-1)-complete normal complex spaces where 
no proof was known until now at all. One reason is the lack of global 
integral kernels or an appropriate d-bar-theory for singular complex 
spaces. In this talk, we will give a d-bar-theoretical proof of Hartogs' 
extension theorem on (n-1)-complete spaces, which is based on Hironaka's 
resolution of singularities, Takegoshi's generalization of the Grauert 
Riemenschneider vanishing theorem and Ehrenpreis'd-bar technique.
http://plone.mat.univie.ac.at/research/groups/scv/seminar08?set_language=en

Dienstag, 11. November, 15:00 Uhr bis 16:30 Uhr, D 103
Arbeitsgemeinschaft Biomathematik
Dr. Claus Rüffler und Hannes Svardal (Universität Wien)
„Polymorphism in time-varying environments”

Dienstag, 11. November, 15:15 Uhr bis 16:45 Uhr, TU Wien, Institut für 
Diskrete Mathematik und Geometrie, Freihaus, grüner Turm (A), 8. Stock, 
Dissertantenraum, Wiedner Hauptstraße 8-10, 1040 Wien
Arbeitsgemeinschaft Diskrete Mathematik
Dr. Johan van Leeuwaarden (Technische Universiteit Eindhoven & EURANDOM)
„Singularity analysis through functional equations for random walks in 
the quarter plane“
Abstract: Stationary distributions of two-dimensional one-step random 
walks in the quarter plane can be obtained by solving functional 
equations. Malyshev pioneered this general problem in the 1970's, and 
the theory has advanced since via its use in applications like lattice 
path counting and two-server queueing models. The crucial idea is to 
reduce the functional equation for the generating function to a standard 
Riemann-Hilbert boundary value problem. We extend the theory by 
presenting a novel technique to derive asymptotic expressions for the 
rare event probabilities. Joint work with Fabrice Guillemin.

Mittwoch, 12. November, 9:30 Uhr bis 11.00 Uhr, 2A180, UZA 2
Complex Analysis Seminar
Prof. Dr. Gerd Schmalz (University of New England)
„Holomorphicity of functions annihilated by a singular vector field”
Abstract: I will talk about the following generalization of Forelli's 
theorem: Suppose F is a holomorphic vector field with singular point at 
p, such that F is linearizable at p and the matrix is diagonalizable 
with the eigenvalues whose ratios are positive reals. Then any function 
φ that has an asymptotic Taylor expansion at p and is holomorphic along 
the complex integral curves of F is holomorphic in a neighborhood of p. 
The requirement for ratios of the eigenvalues to be positive reals is 
necessary.
This is joint work with Kang-Tae Kim and Evgeny Poletsky.
http://plone.mat.univie.ac.at/research/groups/scv/seminar08?set_language=en

Donnerstag, 13. November, 15:00 Uhr, Wolfgang Pauli Institut (WPI)
Seminar an der Technischen Universität Wien, Seminarraum 101C, 4 Fl., 
Wiedner Hauptstraße  8, 1040 Wien
WK Student Seminar
Dipl.-Math. Jens Geier (Technische Universität Wien)
„Asymptotically correct finite difference schemes for highly oscillatory 
linear ODEs“
Abstract: Numerical integration of the one-dimensional stationary 
Schr\"odinger equation $\varepsilon^2\psi(x)_{xx}+(E-V(x))\psi(x) =0 $ 
for a given energy $E > V_{max}$ (or related systems) can be 
time-consuming if $\varepsilon \ll 1$ or $E \gg V_{max}$, because of the 
highly oscillatory nature of the wave function. In this case, standard 
integrators have to use step sizes which are far smaller than the period 
of the solution. To decrease the numerical effort the high oscillations 
of the differential equation are separated and transformed out such that 
the resulting system matrix is uniformly bounded with respect to the 
small parameter $\varepsilon$. The used transformation is related to the 
WKB-approximation of the wave function. Based on the transformed 
equation we sketch the idea how to derive an asymptotic correct 
numerical scheme that can use a far larger step size $h$ than the 
traditional schemes and has an error bound of order 
${\cal{O}}(\varepsilon h^2)$. Additionally, we give a brief review of 
different techniques for the approximation of highly oscillatory 
integrals of the form\begin {eqnarray*}\int_a^b f(x) \,e^{\frac i 
\varepsilon g(x)}\,dx\;. \end{eqnarray*}The mentioned methods are the so 
called asymptotic-, Filon- and Levin-type
method.
Attachment: Abstract als pdf file.

Donnerstag, 13. November, 15:30 Uhr bis 17:00 Uhr, 2A310, UZA 2
Geometry Seminar
Prof. Dr. Dan Burghelea (Ohio State University)
„What can we do with differential forms besides familiar manipulations? 
STRING COHOMOLOGY”
Abstract: Less familiar manipulation with invariant differential forms 
on a (finite or infinite dimensional) smooth $S1-$manifold leads to a 
mild modification of equivariant cohomology in  finite dimensional case 
of some interest. However, when applied to the free loop space of a 
manifold, regarded as an infinite dimensional manifold, this  leads to  
an interesting homotopy functor (string cohomology of the manifold) which:
a) unifies Atyah Hirzebruch  and Waldhausen algebraic K theory at least 
for 1-connected space,
b) provides a convenient homological interpretation of expressions $\int 
e^{\omega}$ on the free loop space of interest in string theory.
The functor is computable, and can be actually defined on the category 
of connected commutative differential graded algebras; however we do not 
know HOW.

Donnerstag, 13. November, 17:00 Uhr, ESI Schrödinger Lecture Hall, 
Boltzmanngasse 9,
1090 Wien
ESI-Seminar
Prof. Dr. Matthias Kreck (Hausdorff Research Institute, Bonn)
„Codes and 3-dimensional manifolds”

Donnerstag, 16. Oktober 2008 bis Donnerstag, 26. Februar 2009
Jeden Donnerstag: 13:00 Uhr bis 15:00 Uhr, ESI Schrödinger Lecture Hall, 
Boltzmanng. 9,
1090 Wien
ESI Senior Research Fellow Program, fall/winter 2008/09
Prof. Dr. Goran Muic (University of Zagreb)
„Selected Topics in the Theory of Automorphic Forms for Reductive Groups“
Abstract: Let G be a reductive algebraic group over Q. Let A be the ring 
of ad' eles of Q. One of the goals of the Langlands program is to 
understand square--integrable automorphic forms which are particularly 
nice functions in L2(G(Q)|G(A)) that contain arithmetic information 
related to the absolute Galois group. According to Langlands, the 
formalism of Eisenstein series is used not only to construct automorphic 
forms but also to construct Lfunctions which appear in a constant term. 
Eisenstein series are meromorphic functions which have complicated 
singularities. We explain how one can use local representation theory to 
study their poles. We explain some applications of the theory of 
Eisenstein series. On the other hand, there are cusp forms which are 
mysterious and there are not so many ways to study them. We explain some 
methods for constructing the cusp forms.

Dienstag, 4. November bis Donnerstag, 27. November
Jeden Dienstag und jeden Donnerstag: 16:00 Uhr bis 18:00 Uhr, ESI 
Schrödinger Lecture Hall, Boltzmanng. 9, 1090 Wien
ESI Senior Research Fellow Program, fall/winter 2008/09
Prof. Dr. Feng Xu (University of California, Riverside)
„Operator Algebras and Conformal Field Theory”
Abstract: In recent years there have been strong connections between 
conformal field theory (CFT) in two dimensions and operator algebras, in 
particular subfactor theory. This course is about come aspects of this 
connection. Our goal is to provide an introduction to two results: the 
first is a construction of a series of CFT using operator algebraic 
techniques, and the second is a result about realization of certain 
intermediate subfactor lattices from CFT which is conjectured to be 
unrealized by subgroups of finite groups.

Wir möchten Sie darauf hinweisen, dass die oben angekündigten Vorträge 
auch auf dem Vortragsserver http://www.mathtalks.ac.at/ zu finden sind.

Mit freundlichen Grüßen

Margit Honkisz
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