SEMINARS
Updated: 4-30-2008
   
APRIL 2008
   
Department Colloquium
Topic: Paint-by-numbers: pattern formation in two-dimensional sheets of cells
Presenter: Stanislav Shvartsman, Princeton University
Date:  Wednesday, April 30, 2008, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: One of the basic mechanisms responsible for the formation of three-dimensional organs relies on the regulated folding of epithelia (two-dimensional sheets of cells). This process is driven by the spatially nonuniform and dynamic distribution of multiple chemical components (products of gene expression) across the epithelia that prepare for folding. Some of the key questions in this class of biological problems are related to the total number of involved genes, the diversity and dynamics of their expression patterns, and the mechanisms of pattern formation. I will present the results of our experimental and computational work that explores these questions during the formation of an elaborate three-dimensional structure (the fruit fly eggshell). I will also try to discuss the mathematical problems associated with the combinatorial construction of complex two-dimensional patterns from a small number of building blocks and dynamics of piecewise linear models of epithelial patter ning.
   
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
Abstract:

See http://orfe.princeton.edu/papers/zhou-abstract.pdf

   
MAY 2008
   
Graduate Student Seminar
Topic: The sixth-sphere
Presenter: Yanir Rubinstein, Columbia University and CMI
Date:  Thursday, May 1, 2008, Time: 12:30 p.m., Location: Fine Hall 214
Abstract: Kirchhoff's problem (1947) asks whether $S^6$ is a complex manifold. We will review basic notions in complex and almost-complex geometry and discuss a bit of what is known regarding this problem, making contact with the octonions, $G_2$, Lie brackets, and curvature.
   
Discrete Mathematics Seminar
Topic: The structure of bullfree graphs
Presenter: Maria Chudnovsky, Columbia University and CMI
Date:  Thursday, May 1, 2008, Time: 2:15 p.m., Location: Fine Hall 314
Abstract: The bull is a graph consisting of a triangle and two disjoint pendant edges. Obvious examples of bullfree graphs are graphs with no triangle, or graphs with no stable set of size three. But there are others (for example, substituting one bullfree graph into another produces a bullfree graph). It turns out, however, that one can explicitly describe all bullfree graphs that cannot be constructed from smaller ones by substitutions. In this talk we will discuss this construction. We will also mention the connection with the Erdos-Hajnal conjecture.
   
Princeton University/Institute for Advanced Study Joint Number Theory Seminar
Topic: Multizeta values and related structures in function field arithmetic
Presenter: D. Thakur, IAS
Date:  Thursday, May 1, 2008, Time: 4:30 p.m., Location: IAS SH-101
   
Topology Seminar
Topic: HF-hat for 3-manifolds with boundary, via a toy example
Presenter: Robert Lipshitz, Columbia University
Date:  Thursday, May 1, 2008, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: We will start by sketching the nature of our extension of HF-hat to 3-manifolds with boundary. Following this, we will focus on a toy model, in terms of planar grid diagrams, in which the main aspects of the theory can be readily seen. We will conclude by mentioning the additional complications not present in the toy model. This is joint work with P. Ozsvath and D. Thurston.
   
Operations Research and Financial Engineering Colloquium
Topic: Game Options, Risk and their Binomial Approximations
Presenter: Yuri Kifer, Hebrew University
Date:  Monday, May 5, 2008, Time: 4:30 p.m., Location: Friends Bowl 004
Abstract: See http://orfe.princeton.edu/papers/kifer-abstract.pdf
   
Operations Research and Financial Engineering Colloquium
Topic: From an analogue of Ewens' measure on the unitary group to the circular Jacobi ensemble
Presenter: Ashkan Nikeghbali, ETH Zurich
Date:  Tuesday, May 6, 2008, Time: 4:30 p.m., Location: E-219 E-Quad
Abstract: See http://orfe.princeton.edu/nikeghbali-abstract1.pdf
   
Analysis Seminar ***Please note special date and time and location
Topic: TBA
Presenter: Juhi Jang, IAS
Date:  Wednesday, May 7, 2008, Time: 2:00 p.m., Location: Fine 314
   
Ergodic Theory and Statistical Mechanics Seminar ***Please note special date
Topic: Nonconvergence examples in averaging
Presenter: Yuri Kifer, Hebrew University
Date:  Wednesday, May 7, 2008, Time: 2:00 p.m., Location: Fine Hall 401
Abstract:

See http://www.math.princeton.edu/~seminar/2007-08-sem/Kifer2008.pdf

   
Princeton University/Institute for Advanced Study Joint Number Theory Seminar
Topic: The Divisor Matrix, Dirichlet Series and SL(2,Z)
Presenter: P. Sin, University of Florida
Date:  Thursday, May 8, 2008, Time: 4:30 p.m., Location: IAS SH-101
Abstract: The divisor matrix is indexed by the natural numbers with (i,j) entry equal to one if i divides j and 0 otherwise. The convolution of a Dirichlet series with the Riemann zeta function corresponds to multiplication of the sequence of coefficients by the divisor matrix. In this talk, we consider groups which contain the divisor matrix and preserve the space of convergent Dirichlet series. A reduction step is to show that the divisor matrix can be brought to a Jordan normal form by transition matrices which preserve the above space. We then construct an representation of SL(2,Z) on the space of convergent Dirichlet series in which the standard unipotent element is represented by the divisor matrix. Finally, we discuss the relation between the zeta function and the Dirichlet series arising from other elements of SL(2,Z) in this representation. Joint work with John G. Thompson.
   
Operations Research and Financial Engineering Colloquium
Topic: Competition, Human Capital, and Growth: a MFG stylized model
Presenter: Jean Michel Lasry, University Paris Dauphine
Date:  Thursday, May 8, 2008, Time: 4:30 p.m., Location: E-219, E-Quad
Abstract: See http://orfe.princeton.edu/lasry-abstract.pdf
   
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