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MARCH 2008 |
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Geometry, Representation Theory, and Moduli Seminar |
Topic: |
TBA |
Presenter: |
E. Carlsson, Princeton University |
Date: |
Wednesday, March 26, 2008, Time: 3:00 p.m., Location: Fine Hall 214 |
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Graduate Seminar |
Topic: |
Counting Circles and Other Things |
Presenter: |
Elena Fuchs
, Princeton University |
Date: |
Thursday, March 27, 2008, Time: 12:30 p.m., Location: Fine Hall 214 |
Abstract: |
Take a circle of radius one and inscribe in it two circles that are tangent to each other. Now add another circle into the original one so that it's tangent to all three. If we repeat this process over and over, we get an old picture known as the Apollonian circle packing. What radii will we get from one such packing? There are many ways to approach this simple question, and I'll tell you about some in this talk. |
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Ergodic Theory and Statistical Mechanics Seminar |
Topic: |
Logarithm laws for horocycles |
Presenter: |
Jayadev Athreya, Princeton University |
Date: |
Thursday, March 27, 2008, Time: 2:00 p.m., Location: Fine Hall 401 |
Abstract: |
In joint work with G. Margulis, we prove a logarithm law for unipotent flows on the space of unimodular lattices in R^n. |
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Operations Research and Financial Engineering Colloquium |
Topic: |
On dimensionality of mean structure from a single data matrix |
Presenter: |
Eckhard Platen, University of Technology, Sydney |
Date: |
Thursday, March 27, 2008, Time: 4:30 p.m., Location: E-219, E-Quad |
Abstract: |
See http://orfe.princeton.edu/papers/platen-abstract.pdf |
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Topology Seminar |
Topic: |
Sequences of Hyperbolic $3$-Manifolds with Unfaithful Markings |
Presenter: |
Ian Biringer, University of Chicago |
Date: |
Thursday, March 27, 2008, Time: 4:30 p.m., Location: Fine Hall 314 |
Abstract: |
Let $\Gamma $ be a finitely generated group. To every representation $\rho : \Gamma \to Isom (\BH3) $ with discrete and torsion-free image there corresponds a hyperbolic $3$-manifold $M_\rho = \BH3 / \rho (\Gamma) $. I will present some new results linking the pointwise convergence of a> sequence of such representations with Gromov-Hausdorff convergence of the corresponding quotient manifolds. A detailed analysis already exists for > sequences of faithful representations; I will give examples that illustrate the failure of these theorems in the unfaithful setting, and offer some useful replacements. Joint work with Juan Souto. |
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Differential Geometry and Geometric Analysis Seminar |
Topic: |
TBA |
Presenter: |
Marianty Ionel, University of Toledo |
Date: |
Friday, March 28, 2008, Time: 3:00 p.m., Location: Fine Hall 314 |
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Differential Geometry and Geometric Analysis Seminar ***Please note special time |
Topic: |
A priori estimates for special Lagrangian equations |
Presenter: |
Micah Warren, University of Washington |
Date: |
Friday, March 28, 2008, Time: 4:00 p.m., Location: Fine Hall 314 |
Abstract: |
We discuss recent a priori interior Hessian estimates for solutions of the special Lagrangian equation, when the equation has phase at least a certain value, or when the solution is convex. These equations include the sigma-2 equation in dimension three. The gradient graph of any solution is a minimizing Lagrangian surface. While Heinz showed in the 50's that similar estimates hold for the sigma-2 (Monge-Ampere) equation in dimension two, Pogorelov showed that such estimates cannot hold for the sigma-3 (Monge-Ampere) equation in dimension three. This is joint work with Yu Yuan, partly also with Jingyi Chen. |
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Group Actions Seminar |
Topic: |
Local rigidity for some rank two algebraic abelian actions |
Presenter: |
Danijela Damjanovic, Harvard University |
Date: |
Monday, March 31, 2008, Time: 12:15 p.m., Location: Fine Hall 224 |
Abstract: |
I will discuss local rigidity for some rank-two actions: partially hyperbolic on SL(n, R)/L, for n>3; and parabolic on SL(2, R)XSL(2, R)/L. |
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PACM Colloquium |
Topic: |
Mathematical and Computational Challenges in Shear Stiffness Imaging of Tissue: Can cancerous and benign lesions be distinguished? |
Presenter: |
Joyce McLaughlin, Mathematical Sciences, Rensselaer Polytechnic Institute |
Date: |
Monday, March 31, 2008, Time: 4:00 p.m., Location: Fine Hall 214 |
Abstract: |
For centuries doctors have palpated tissue to detect abnormalities. We target imaging the stiffness the doctor feels in the palpation exam, including imaging deeper than what can be felt in this exam and distinguishing between benign and cancerous lesions. Current applications include breast and prostate cancer. Current experimentalists with whom we collaborate are: Dr. Richard Ehman, Mayo Clinic; Mathias Fink, ESPCI, Paris; and Dr. Kevin Parker at the University of Rochester. We describe the challenges and opportunities for imaging, including mathematical modeling and algorithmic development, with the data from the individual experiments |
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APRIL 2008 |
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Algebraic Geometry Seminar |
Topic: |
Real singular Del Pezzo surfaces and rationally connected threefolds |
Presenter: |
Frédéric Mangolte, Université de Savoie |
Date: |
Tuesday, April 1, 2008, Time: 4:30 p.m., Location: Fine Hall 322 |
Abstract: |
Recent results on classification of real algebraic threefolds will be described. Let W -> X be a real smooth projective threefold fibred by rational curves. J. Kollár proved that if the set of real points W(R) is orientable, then a connected component N of W(R) is essentially either a Seifert fibred manifold or a connected sum of lens spaces. We proved sharp estimates on the number and the multiplicities of the Seifert fibres and on the number and the torsions of the lens spaces whenever X is a geometrically rational surface. These results answer in the affirmative three questions of Kollár. They are derived from a careful study of real singular Del Pezzo surfaces with only Du Val singularities. This is joint work with F. Catanese. |
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Mathematical Physics Seminar |
Topic: |
Localisation in the Anderson tight binding model with several particles |
Presenter: |
Y. Suhov, University of Cambridge, UK |
Date: |
Tuesday, April 1, 2008, Time: 4:30 p.m., Location: Jadwin 343 |
Abstract: |
The Anderson model (which will celebrate its 50th anniversary in 2008) is among most popular topics in the random matrix and operator theory. However, so far the attention here was concentrated on single-particle models, where the random external potential is either IID or has a rapid decay of spatial correlations. Multi-particle models remained out of scope in mathematical (and, surprisingly, physical) literature. Recently, Chulaevsky and Suhov (2007) proposed a version of the multi-scale analysis (MSA) scheme tackling the multi-particle case. I'll discuss one of results in this direction: localisation in the lattice (tight binding) multi-particle models for large values of the amplitude (coupling) constant. |
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Operations Research and Financial Engineering Colloquium |
Topic: |
Modelling high dimensional daily volatilities based on high-frequency data |
Presenter: |
Qiwei Yao, London School of Economics |
Date: |
Tuesday, April 1, 2008, Time: 4:30 p.m., Location: E-219, E-Quad |
Abstract: |
See http://orfe.princeton.edu/papers/yao-abstract.pdf |
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Geometry, Representation Theory, and Moduli Seminar |
Topic: |
TBA |
Presenter: |
B. Fantechi, SISSA and IAS |
Date: |
Wednesday, April 2, 2008, Time: 3:00 p.m., Location: Fine Hall 214 |
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Department Colloquium |
Topic: |
TBA |
Presenter: |
Nalini Anantharaman,
Ecole Polytechnique |
Date: |
Wednesday, April 2, 2008, Time: 4:30 p.m., Location: Fine Hall 314 |
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Discrete Mathematics Seminar |
Topic: |
TBA |
Presenter: |
János Pach, NYU and Courant Institute |
Date: |
Thursday, April 3, 2008, Time: 2:15 p.m., Location: Fine Hall 314 |
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Topology Seminar |
Topic: |
Length Spectrum of a Flat Metric |
Presenter: |
Chris Leininger, University of Illinois, Urbana |
Date: |
Thursday, April 3, 2008, Time: 4:30 p.m., Location: Fine Hall 314 |
Abstract: |
I'll discuss joint work-in-progress with M. Duchin and K. Rafi on the geometry of flat structures on surfaces via the lengths of its closed geodesics. |
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Differential Geometry and Geometric Analysis Seminar |
Topic: |
TBA |
Presenter: |
Jeff Cheeger, New York University |
Date: |
Friday, April 4, 2008, Time: 3:00 p.m., Location: Fine Hall 314 |
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Group Actions Seminar |
Topic: |
TBA |
Presenter: |
Kariane Calta, Vassar College |
Date: |
Monday, April 7, 2008, Time: 12:15 p.m., Location: Fine Hall 224 |
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Operations Research and Financial Engineering Colloquium |
Topic: |
Pricing American Contingent Claims by Stochastic Linear Programming |
Presenter: |
Mustafa Pinar, Bilkent University |
Date: |
Tuesday, April 8, 2008, Time: 3:30 p.m., Location: E-219, E-Quad |
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Mathematical Physics Seminar |
Topic: |
TBA |
Presenter: |
E. Akkermans, Technion |
Date: |
Tuesday, April 8, 2008, Time: 4:30 p.m., Location: Jadwin 343 |
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Geometry, Representation Theory, and Moduli Seminar |
Topic: |
TBA |
Presenter: |
B. Kim, KIAS |
Date: |
Wednesday, April 9, 2008, Time: 3:00 p.m., Location: Fine Hall 214 |
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Department Colloquium |
Topic: |
TBA |
Presenter: |
Marc Levine, Northeastern University |
Date: |
Wednesday, April 9, 2008, Time: 4:30 p.m., Location: Fine Hall 314 |
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Discrete Mathematics Seminar |
Topic: |
Averaging Points Two at a Time |
Presenter: |
David Moulton, IDA-CCR |
Date: |
Thursday, April 10, 2008, Time: 2:15 p.m., Location: Fine Hall 314 |
Abstract: |
In 2006 Brendan McKay asked the following on sci.math.research: We have n points in a disk centered at the centroid of the points. We successively replace the two furthest points from each other by two copies of their average. (After each move we still have n points with the same centroid. How many moves are necessary to guarantee that all points lie in the concentric disk of half the radius?
This really is the wrong question: it turns out that the situation is easier to study of we use a general Euclidean space and look at the rate of decay of the diameter in terms of number of moves. We get sharp asymptotic upper and lower bounds on the maximum diameter after certain numbers of moves. This involves interesting geometrical configurations and simple linear-programming arguments. |
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Topology Seminar |
Topic: |
On the renormalized volume of quasifuchsian manifolds |
Presenter: |
Jean-Marc Schlenker, Toulouse |
Date: |
Thursday, April 10, 2008, Time: 4:30 p.m., Location: Fine Hall 314 |
Abstract: |
The renormalized volume of quasifuchsian hyperbolic 3-manifolds was originally introduced for physical reasons. Takhtajan and Zograf (and others) discovered that it provides a Kähler potential for the Weil-Petersson metric on Teichmüller space. We will give an elementary, differential-geometric account of this result. It can be extended to quasifuchsian manifolds having cone singularities along infinite lines, yielding results on the Teichmüller space of hyperbolic metrics with cone singularities (of prescribed angles) on a closed surface. (Based on joint works with K. Krasnov, C. Lecuire, S. Moroianu.) |
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Symplectic Geometry Seminar |
Topic: |
Mirror symmetry of Fano toric A-model and Landau-Ginzburg B-model |
Presenter: |
Yong-Geun Oh,University of Wisconsin |
Date: |
Friday, April 11, 2008, Time: 2:00 p.m., Location: Fine Hall 314 |
Abstract: |
In this talk, I will introduce the notion of weakly unobstructed Lagrangian submanifolds and balanced Lagrangian submanifolds. I will explain construction of certain potential function constructed out of study of deformation theory of Floer cohomology and explain its relationship to the earlier work of Givental which advocates that quantum cohomology ring is isomorphic to the Jacobian ring of Landau-Ginzburg superpotential. I will explain these result in the context of mirror symmetry between Fano toric A-model and Landau-Ginzburg B-model. If time permits, I will indicate how this study can be related to construction of Entov-Polterovich's symplectic quasi-states on toric manifolds. |
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Differential Geometry and Geometric Analysis Seminar |
Topic: |
TBA |
Presenter: |
Spyros Alexakis, Princeton University |
Date: |
Friday, April 11, 2008, Time: 3:00 p.m., Location: Fine Hall 314 |
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Analysis Seminar |
Topic: |
The Composite Membrane Problem |
Presenter: |
Sagun Chanillo, Rutgers University |
Date: |
Monday, April 14, 2008, Time: 4:00 p.m., Location: Fine Hall 110 |
Abstract: |
We wish to build a body of prescribed shape, and of prescribed mass out of materials of varying density so as to minimize the first Dirichlet eigenvalue with fixed boundary of the body. Existence, uniqueness and regularity of the solution and the resulting free boundary problem will be discussed. |
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PACM Colloquium |
Topic: |
Airplane boarding and space-time geometry |
Presenter: |
Eitan Bachmat, Computer Science, Ben-Gurion University and Brandeis University |
Date: |
Monday, April 14, 2008, Time: 4:00 p.m., Location: Fine Hall 214 |
Abstract: |
It is hard to think of a process that is more boring than boarding an airplane. In the hope of relieving, or at least shortening, some of the pain, airlines have devised various boarding strategies such as back-to-front, window to aisle, boarding by zones or even unassigned seating. In the talk we will try to overturn the negative image that airplane boarding has and will try to portray it as a very exciting process which is modeled via space-time (a.k.a Lorentzian) geometry with a touch of random matrix theory. Using the model we will try to figure out what are the better strategies. If time permits, we will use insights from the airplane borading process to suggest an interpretation for Einstein's law of motion in which god plays the ultimate dice game. The talk is entirely self contained. Partly based on joint works with D. Berend, L. Sapir, S. Skiena, M. Elkin and V. Khachaturov. |
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Algebraic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Rajesh Kulkarni, Michigan State University |
Date: |
Tuesday, April 15, 2008, Time: 4:30 p.m., Location: Fine Hall 322 |
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Mathematical Physics Seminar |
Topic: |
TBA |
Presenter: |
lya Goldsheid, Queen Mary, University of London |
Date: |
Tuesday, April 15, 2008, Time: 4:30 p.m., Location: Jadwin 343 |
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Operations Research and Financial Engineering Colloquium |
Topic: |
TBA |
Presenter: |
Lisa Goldberg |
Date: |
Tuesday, April 15, 2008, Time: 4:30 p.m., Location: E-219, E-Quad |
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Mathematical Physics Seminar ***Please note special date |
Topic: |
TBA |
Presenter: |
P. Exner, Physics Inst., Czech Academy |
Date: |
Thursday, April 17, 2008, Time: 4:30 p.m., Location: Jadwin 343 |
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Symplectic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Sergio Lukic, Rutgers University |
Date: |
Friday, April 18, 2008, Time: 2:00 p.m., Location: Fine Hall 314 |
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Differential Geometry and Geometric Analysis Seminar |
Topic: |
TBA |
Presenter: |
Mu-Tao Wang, Columbia University |
Date: |
Friday, April 18, 2008, Time: 3:00 p.m., Location: Fine Hall 314 |
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Group Actions Seminar |
Topic: |
TBA |
Presenter: |
Francois Maucourant, Rennes 1 University |
Date: |
Monday, April 21, 2008, Time: 12:15 p.m., Location: Fine Hall 224 |
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Analysis Seminar |
Topic: |
TBA |
Presenter: |
Joachim Krieger, University of Pennsylvania |
Date: |
Monday, April 21, 2008, Time: 4:00 p.m., Location: Fine Hall 110 |
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Algebraic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Robert Lazarsfeld, University of Michigan |
Date: |
Tuesday, April 22, 2008, Time: 4:30 p.m., Location: Fine Hall 322 |
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Mathematical Physics Seminar |
Topic: |
Long range order for lattice dipoles |
Presenter: |
Alessandro Giuliani, University of Rome |
Date: |
Tuesday, April 22, 2008, Time: 4:30 p.m., Location: Jadwin 343 |
Abstract: |
We consider a system of classical Heisenberg spins on a cubic lattice in dimensions three or more, interacting via the dipole-dipole interaction. We prove that at low enough temperature the system displays orientational long range order, as expected by spin wave theory. The proof is based on reflection positivity methods. In particular, we demonstrate a previously unproven conjecture on the dispersion relation of the spin waves, first proposed by Froehlich and Spencer, which allows one to apply infrared bounds for estimating the long distance behavior of the spin-spin correlation functions. |
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Operations Research and Financial Engineering Colloquium |
Topic: |
TBA |
Presenter: |
Jonathan Eckstein, Rutgers University |
Date: |
Tuesday, April 22, 2008, Time: 4:30 p.m., Location: E-219, E-Quad |
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Geometry, Representation Theory, and Moduli Seminar |
Topic: |
TBA |
Presenter: |
P. Johnson, University of Michigan |
Date: |
Wednesday, April 23, 2008, Time: 3:00 p.m., Location: Fine Hall 214 |
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Department Colloquium |
Topic: |
TBA |
Presenter: |
Jim Bryan, UBC |
Date: |
Wednesday, April 23, 2008, Time: 4:30 p.m., Location: Fine Hall 314 |
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Differential Geometry and Geometric Analysis Seminar |
Topic: |
TBA |
Presenter: |
Yisong Yang, Poly. Tech. in New York |
Date: |
Friday, April 25, 2008, Time: 3:00 p.m., Location: Fine Hall 314 |
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Group Actions Seminar |
Topic: |
TBA |
Presenter: |
Alex Furman, University of Illinois at Chicago |
Date: |
Monday, April 28, 2008, Time: 12:15 p.m., Location: Fine Hall 224 |
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PACM Colloquium |
Topic: |
Active and Semi-Supervised Learning Theory |
Presenter: |
Rob Nowak, Electrical and Computer Engineering, University of Wisconsin-Madison |
Date: |
Monday, April 28, 2008, Time: 4:00 p.m., Location: Fine Hall 214 |
Abstract: |
Science is arguably the pinnacle of human intellectual achievement, yet the scientific discovery process itself remains an art. Human intuition and experience is still the driving force of the high-level discovery process: we determine which hypotheses and theories to entertain, which experiments to conduct, how data should be interpreted, when hypotheses should be abandoned, and so on. Meanwhile machines are limited to low-level tasks such as gathering and processing data. A grand challenge for scientific discovery in the 21st century is to devise machines that directly participate in the high-level discovery process. Towards this grand challenge, we must formally characterize the limits of machine learning. Statistical learning theory is usually based on supervised training, wherein a learning algorithm is presented with a finite set of i.i.d. labeled training examples. However, modern experimental methods often generate incredibly large numbers of unlabeled data for very little expense, while the task of labeling data is often painstaking and costly. Machine learning methods must leverage the abundance of unlabeled data in scientific problem domains. Active learning (AL) and semi-supervised learing (SSL) are two well known approaches to exploit unlabeled data. In both paradigms one has access to a large pool of unlabeled examples, and only a few labeled examples are provided or selected. AL is a sequential feedback process. Unlabeled examples that are predicted to have very informative labels, based on previously gathered labeled and unlabeled data, are selected for labeling. In SSL, labeled examples are randomly provided, without regard to potential informativeness. Today, little is known about theoretical limits of AL and SSL performance. Sparsity and complexity of the underlying data-generating distributions appear to play a central role in the performance of AL and SSL, and this talk will discuss some of the known theoretical results.
This work is joint with Rui Castro, Aarti Singh and Jerry Zhu. |
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Algebraic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Brendan Hassett, Rice University |
Date: |
Tuesday, April 29, 2008, Time: 4:30 p.m., Location: Fine Hall 322 |
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Operations Research and Financial Engineering Colloquium |
Topic: |
TBA |
Presenter: |
Farid AitSahlia, University of Florida |
Date: |
Tuesday, April 29, 2008, Time: 4:30 p.m., Location: E-219, E-Quad |
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Department Colloquium |
Topic: |
TBA |
Presenter: |
Stanislav Shvartsman, Princeton University |
Date: |
Wednesday, April 30, 2008, Time: 4:30 p.m., Location: Fine Hall 314 |
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Operations Research and Financial Engineering Colloquium |
Topic: |
Behavioral Portfolio Choice in Continuous Time |
Presenter: |
Xunyu Zhou, University of Oxford |
Date: |
Wednesday, April 30, 2008, Time: 4:30 p.m., Location: E-219, E-Quad |
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MAY 2008 |
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Topology Seminar |
Topic: |
TBA |
Presenter: |
Robert Lipshitz, Columbia University |
Date: |
Thursday, May 1, 2008, Time: 4:30 p.m., Location: Fine Hall 314 |
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Group Actions Seminar |
Topic: |
TBA |
Presenter: |
Manfred Einsiedler, Ohio State University |
Date: |
Monday, May 5, 2008, Time: 12:15 p.m., Location: Fine Hall 224 |
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Operations Research and Financial Engineering Colloquium |
Topic: |
TBA |
Presenter: |
Alex Lipton |
Date: |
Tuesday, May 6, 2008, Time: 4:30 p.m., Location: Location: E-219, E-Quad |
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Operations Research and Financial Engineering Colloquium |
Topic: |
TBA |
Presenter: |
Jean Michel Lasry |
Date: |
Thursday, May 8, 2008, Time: 4:30 p.m., Location: E-219, E-Quad |
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Operations Research and Financial Engineering Colloquium |
Topic: |
TBA |
Presenter: |
Paulo Silva, University of Sao Paulo |
Date: |
Thursday, May 15, 2008, Time: 4:30 p.m., Location: E-219, E-Quad |
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