[Vortraege] Vortragsankündigungen der komm. Woche (KW13)

Fri Mar 20 13:43:32 CET 2009

Sehr geehrte Fakultätsmitglieder,

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

Mit freundlichen Grüßen
Margit Honkisz

Mittwoch, 25. März, 15:00 Uhr bis 15:45 Uhr, C 209, UZA 4
Junior Kolloquium
Prof. Dr. Ivar Ekeland (University of British Columbia, Institute of 
Mathematics)
In the junior Colloquium the speaker of the Mathematical Colloquium will 
give an introduction into subject of the Mathematical Colloquium. This 
week Ivar Ekeland will give a seminar with the title:
„Do utility functions exist ? A geometric approach.“
He will show how basic questions in microeconomics can be solved using 
the exterior differential calculus of Elie Cartan.

15:45 Uhr bis 16:15 Uhr: K & K im Common Room

Mittwoch, 25. März, 16:15 Uhr bis 17:00 Uhr, C 209, UZA 4
Mathematisches Kolloquium
Prof. Dr. Ivar Ekeland (University of British Columbia, Institute of 
Mathematics) 
„Optimal transport and the pricing of quality“
Optimal transport is the common mathematical structure underlying 
diverse topics in economics. These lectures will cover two of them, 
namely adverse selection and hedonic markets. Both have to do with the 
pricing of quality goods, either by a monopolist or by a competitive 
market. I will also give some idea of numerical problems (including the 
Gale-Shapley algorithm). Notes will be available.

(Dekan Univ.-Prof. Dr. Harald Rindler, Univ.-Prof. Dr. Walter Schachermayer)

Montag, 23. März, 13:15 Uhr bis 14:00 Uhr, D 107, UZA 4
Im Rahmen des Seminars „Transporttheorie“ von o. Univ.-Prof. Dr. Walter 
Schachermayer spricht:
Prof. Dr. Ivar Ekeland (University of British Columbia, Institute of 
Mathematics)
„Optimal transport and the pricing of quality“
Optimal transport is the common mathematical structure underlying 
diverse topics in economics. These lectures will cover two of them, 
namely adverse selection and hedonic markets. Both have to do with the 
pricing of quality goods, either by a monopolist or by a competitive 
market. I will also give some idea of numerical problems (including the 
Gale-Shapley algorithm). Notes will be available.

Montag, 23. März, 14:00 Uhr bis 15:00 Uhr, D 107, UZA 4
Im Rahmen des Seminars „Transporttheorie“ von o. Univ.-Prof. Dr. Walter 
Schachermayer spricht:
Dr. Santiago Moreno (Humboldt Universität Berlin)
„Solving variational problems with global convexity constraints: a 
numerical method“
An algorithm to approximate the solutions to a class of variational 
problems subject to global convexity constraints will be presented. In 
other words, the admissible set will consist exclusively of convex 
functions. The main motivation for studying this numerical method is to 
compute solutions to
Adverse Selection problems within a Principal-Agent framework. Problems 
such as product lines design, optimal taxation, structured derivatives 
design, etc. can be studied through the scope of these models. The 
algorithm relies on the well known fact that continuous convex functions 
can be expressed as pointwise suprema of affine functions. In contrast 
with what is moslty found in the literature, this is not a 
finite-elements method. This is joint work with Ivar Ekeland.

Dienstag, 24. März, 14:30 Uhr, ESI Schrödinger Lecture Hall, 
Boltzmanngasse 9, 1090 Wien
ESI-Seminar
Dr. Konstantin Medynets (Kharkov, ESI Junior Research Fellow)
„Bratteli diagrams for aperiodic homeomorphisms of a Cantor set“
In 1992 it was shown by Herman, Putnam, and Skau that every minimal 
homeomorphism can be realized as a Vershik (addic) map on the path space 
of a Bratteli diagram. This result helped them later
find a complete set of invariants for orbit and strong orbit equivalence 
of minimal systems. The very construction of Bratteli diagram was 
achieved by exploiting nice recurrence properties of minimal systems. In 
the talk, I plan to show that we can find a Bratteli-Vershik realization 
even if the condition of minimality is dropped. Namely, we will do that 
for the class of aperiodic (every orbit is just infinite) systems. I 
explain how we can use Bratteli diagrams to describe the simplex of 
invariant measures for
dynamical systems. I also present several examples of dynamical systems 
which look very alike, but have significantly different simplexes of 
invariant measures, and, therefore, are not isomorphic.

Dienstag, 24. März, 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
Konstantinos Panagiotou (Max Planck Institut für Informatik, Saarbrücken)
„Extremal Subgraphs of Random Graphs“
For a graph G, let ET(G) denote the maximum number of edges in a 
triangle-free subgraph (not necessarily induced) of G, and let EB(G) be 
the maximum number of edges in a bipartite subgraph of G. Of course, we 
always have ET(G) >= EB(G), but the general intuition -- guided by 
various known results -- suggests that, for dense enough graphs, these 
two parameters will typically be equal. In 1990, Babai, Simonovits and 
Spencer studied these parameters for random graphs G(n,p) and confirmed 
this intuition for dense graphs. In particular, they proved that there 
is a small positive constant c such that, for p >= 1/2 - c, with high 
probability we have ET(G(n,p)) = EB(G(n,p)). Babai, Simonovits and 
Spencer asked whether this result could be extended to cover all 
constant values of p. In this talk we answer this question affirmatively 
and show that the above property in fact holds whenever p=p(n) >= 
n^{-c}, for some fixed c > 0. This is joint work with Graham Brightwell 
and Angelika Steger.

Donnerstag, 26. März, 15:00 Uhr, TU Wien, Freihaus, grüner Turm, 3. 
Stock, Seminarraum 101B, Wiedner Hauptstraße 8, 1040 Wien
WK student seminar
Matthias Kornfeld
„Local Interaction Theory for Laminar Transonic Flows in Slender Channels“
Transonic flows through channels so narrow that the classical boundary 
layer approach fails are considered. As a consequence the properties of 
the inviscid core and the viscosity dominated boundary layer region can 
no longer be determined in subsequent steps but have to be calculated 
simultaneously. The resulting viscous inviscid interaction problem for 
weak three dimensional laminar flows is formulated for perfect gases 
under the requirement that the channel is sufficiently narrow so that 
the flow outside the viscous wall layer becomes planar in the leading 
order approximation. Representative solutions for subsonic as well as 
for supersonic flows disturbed by three dimensional surface mounted 
obstacles will be presented.

Donnerstag, 26. März, 15:30 Uhr, 2A310, UZA 2
Geometry Seminar
Mag. Günther Waxenegger
„On asymptotically flat initial data sets for the Einstein vacuum 
equations II“
After reviewing the notion of an initial data set for the Einstein 
equations, we prove the existence of a certain class of asymptotically 
flat initial data sets with small but non-vanishing momenta. In 
particular, the proof uses the implicit function theorem in suitable 
Banach spaces.

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