Current Seminars
updated 11/12/2003

   

NOVEMBER 12-14, 2003

   
Discrete Mathematics Seminar
Topic: Mixing and Shuffling
Presenter:  Peter Winkler, Bell Labs and the Institute for Advanced Study
Date:  Wednesday, November 12, 2003, Time: 2:15 p.m., Location: Fine Hall 322
Abstract: See www.math.princeton.edu/~bsudakov/winkler2003.ps
   
Geometry, Representation Theory, and Moduli Seminar
Topic: Counting vacua of string theory
Presenter:  Michael Douglas, Rutgers University
Date:  Wednesday, November 12, 2003, Time: 3:00 p.m., Location: Fine Hall 214
Abstract: The best known links between string theory and algebraic geometry involve enumerative problems, for example counting curves using mirror symmetry or quantum cohomology theory.  We give an introduction for mathematicians to a class of counting problems of far greater physical interest, and which are beginning to be mathematically accessible: counting vacuum solutions which meet simplified versions of the criteria used in real world physics.
   
Department Colloquium
Topic: Twisting in stringy orbitfold
Presenter:  Yongbin Ruan, University of Wisconsin
Date:  Wednesday, November 12, 2003, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: Stringy orbifold is a new emerging field of mathematics for last a few years. It has its root in physics and connections to many branches of mathematics such as algebraic geometry, algebraic topology and representation theory. One important aspect of stringy orbifold is twisting process. The first twisting is discrete torsion invented by physcist C. Vafa. Recently, gerbe is emerging as a leading candidate. The talk will try to explain all these connections.
   
Ergodic Theory and Statistical Mechanics Seminar
Topic: Stochastic Loewner equations (tutorial talks)
Presenter: Leonid Koralov, Princeton University
Date: Thursday, November 13, 2003, Time: 2:00 p.m., Location: Fine Hall 224
   
Joint Analysis Seminar
Topic: Multichannel Nonlinear Scattering
Presenter: Avraham Soffer, Institute for Advanced Study and Rutgers University
Date: Thursday, November 13, 2003, Time: 3:30 p.m., Location: Fine Hall 224
Abstract: Analysis of the large time behavior of Nonlinear Dispersive equations is important in many fields of science. The dyanmics of Solitons , Vortices, Kinks and other coherent structures of the fundamental equations of Mathematical  Physics, are all manifestations of the problem asymptotic stability and completeness of nonlinear dispersive waves.  In this talk I'll describe the general problem for NLS type equations and the recent results on NLS with Multibound states.
   
Joint Institute for Advanced Study/Princeton University Number Theory Seminar
Topic: On some singular exponential sums
Presenter: Steven Sperber, University of Minnesota and Princeton University
Date: Thursday, November 13, 2003, Time: 4:15 p.m., Location: Fine Hall 322
   
Topology Seminar
Topic: Some examples of virtually Haken and virtually fibered three-manifolds
Presenter: Genevieve Walsh, University of Texas at Austin
Date: Thursday, November 13, 2003, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: We show that all two-bridge knot complements  and many  Montesinos knot complements are virtually fibered.  We also prove some results about the existence of virtually Haken Dehn fillings on two-bridge knot complements.  Specifically, if a two-bridge knot can be written as a rational knot K_{p/q} with p/q < 1/4, then infinitely many fillings of the knot complement S^3 - K_{p/q} are virtually Haken. The main tool in this work is analyzing covers of the knot complements by geodesic link complements.
   
Geometric Analysis Seminar
Topic: On the positivity of mass for asymptotically Anti-de Sitter spacetimes
Presenter: Greg Galloway, University of Miami
Date: Friday, November 14, 2003, Time: 3:00 p.m., Location: Fine Hall 314
   

NOVEMBER 17-21, 2003

   
Special Analysis Seminar
Topic: On weak density of smooth maps for the Dirichlet energy between manifolds
Presenter: Fengbo Hang, Princeton University
Date: Monday, November 17, 2003, Time: 4:00 p.m., Location: Fine Hall 314
   
PACM Seminar
Topic: Biological Molecular Algorithms -- A Mathematician’s Perspective on Molecular Biology
Presenter: Barry Merriman, University of California, Los Angeles
Date: Monday, November 17, 2003, Time: 4:00 p.m., Location: Fine Hall 214
Abstract: Coming from applied mathematics, I have spent three years working in molecular biology, with the goal of merging mathematical and molecular techniques to create new tools for studying biology at the "genomic" scale. In this talk, I will briefly summarize the state of genomics, and then attempt to answer the frequently asked question "Where's the Math?". Towards this end, I will present a hidden but central role that mathematical concepts play in this field.

The incredible pace of development in molecular biology is driven by breakthroughs in manipulating DNA. From a mathematician’s perspective, these experimental techniques—such as DNA sequencing—can be viewed as clever “algorithms”, based on operators unique to the biological “programming language”. These are executed in a loosely organized “bio-computer” composed of DNA, enzymes, and diverse components for “I/O and memory”. The current situation is similar to the early development of computers, when both algorithms and the hardware used to execute them were rapidly and cooperatively evolving.

I will present Molecular Biology from this algorithmic perspective, by interpreting the major techniques of DNA manipulation as biomolecular algorithms. I will also present new algorithms from my own genomics research, motivated by this way of thinking. The talk will be understandable to mathematicians and computer scientists with no biological background, and will emphasize the fundamental role that biomolecular algorithms will play in solving the outstanding problems of genomics. I also hope to promote the idea that researchers from “abstract” mathematical disciplines can make key contributions to this important area of Molecular Biology.

   
Algebraic Geometry Seminar  *** Please note change in date
Topic: The orbifold Chow ring of toric Deligne-Mumford stacks
Presenter: Linda Chen, Columbia University
Date: Tuesday, November 18, 2003, Time: 4:30 p.m., Location: Fine Hall 322
Abstract: Orbifold cohomology and Chow ring theories have recently been developed -- their invariants coincide with classical invariants of a nice (crepant) resolution of singularities. We introduce a theory of toric Deligne-Mumford stacks, compute their orbifold Chow rings, and give a connection to resolutions of singularities. This is joint work with Lev Borisov and Greg Smith.
   
Mathematical Physics Seminar
Topic: Lieb-Thirring inequalities and absolutely continuous spectrum of Schroedinger operators
Presenter: Ari Laptev, Technical University Stockholm
Date: Tuesday, November 18, 2003, Time: 4:30 p.m., Location: Jadwin A06
Abstract: The aim of this talk is to extend a class of potentials for  which the absolutely continuous spectrum of the corresponding multidimensional Schroedinger operator is essentially supported by [0, infnity). Our main theorem states that this property is preserved for slowly decaying potentials provided that there are some oscillations with respect to one of the variables.
   
Joint Institute for Advanced Study/Princeton University Complex Geometry Seminar
Topic: Hodge theory and Geometry, I
Presenter: Phillip Griffiths, Institute for Advanced Study
Date: Wednesday, November 19, 2003, Time: 1:00 p.m., Location: Fine Hall 401
   
Discrete Mathematics Seminar
Topic: Group algebras, expanders and codes
Presenter:  Avi Wigderson, the Institute for Advanced Study and Hebrew University
Date:  Wednesday, November 19, 2003, Time: 2:15 p.m., Location: Fine Hall 322
Abstract: See www.math.princeton.edu/~bsudakov/avi2003.ps
   
Geometry, Representation Theory, and Moduli Seminar
Topic: Topological vertex and the instanton calculus
Presenter:  Amer Iqbal, Harvard University
Date:  Wednesday, November 19, 2003, Time: 3:00 p.m., Location: Fine Hall 214
Abstract: After a brief review of topological vertex I will discuss the topologial string partition function of various geometries and the relation with localization calculations on instanton moduli spaces. I will also discuss a generalization of topological string partition function, inspired by the instanton calculus, which encodes refined
integer invariants.
   
Department Colloquium
Topic: L-values and Congruences
Presenter:  Chris Skinner, University of Michigan
Date:  Wednesday, November 19, 2003, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: See www.math.princeton.edu/~seminar/2003-04-sem/SkinnerAbstract11-19-2003.pdf
   
Ergodic Theory and Statistical Mechanics Seminar
Topic: Dyadic models for the equations of fluid motion
Presenter: Natasa Pavlovic, Princeton University
Date: Thursday, November 20, 2003, Time: 2:00 p.m., Location: Fine Hall 224
Abstract: In this talk we shall introduce dyadic models for the Euler and the Navier-Stokes equations and will discuss some results that were obtained for these models. For the scalar dyadic Euler equations we prove finite time blow-up, and in the context of the scalar dyadic Navier-Stokes equations with hyper-dissipation we prove finite time blow-up in case when the degree of dissipation is sufficiently small (joint work with Nets Katz). These results can be generalized to analogous results for a vector dyadic model (recent joint work Susan Friedlander), and we shall present them in the talk.
   
Joint Analysis Seminar
Topic: Compactness of solutions to the Yamabe problem
Presenter: Yanyan Li, Rutgers University
Date: Thursday, November 20, 2003, Time: 3:30 p.m., Location: Fine Hall 224
   
Joint Institute for Advanced Study/Princeton University Number Theory Seminar
Topic: TBA
Presenter: Ye Tian, Institute for Advanced Study
Date: Thursday, November 20, 2003, Time: 4:15 p.m., Location: Fine Hall 322
   
Topology Seminar
Topic: Parageometric automorphisms of free groups (joint work with Michael Handel)
Presenter: Lee Mosher, Rutgers University - Newark
Date: Thursday, November 20, 2003, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: Geometric automorphims of free groups are those which are represented by an automorphisms of a surface with one hole. Parageometric automorphisms are those which are not geometric but which are represented, in some nice manner, by an automorphism of a certain 2-complex. We study the dynamics of parageometric automorphisms, finding analogies and constrasts with geometric automorphisms. As an application, we prove that the exponential growth rate of a parageometric automorphism (which is irreducible with irreducible powers) is strictly greater than the exponential growth rate of its inverse.
   
Joint Columbia University/Courant Institute/Princeton University Differential Geometry Seminar
Topic: The Ricci flow I
Presenter: Richard Hamilton, Columbia University
Date: Friday, November 21, 2003, Time: 2:00 p.m., Location: Courant Institute, New York
   
Joint Columbia University/Courant Institute/Princeton University Differential Geometry Seminar
Topic: The Ricci flow II
Presenter: Richard Hamilton, Columbia University
Date: Friday, November 21, 2003, Time: 3:30 p.m., Location: Courant Institute, New York
   

NOVEMBER 24-28, 2003

   
PACM Seminar
Topic: Eavesdropping on Synaptic Traffic
Presenter: Steve Cox, Rice University
Date: Monday, November 24, 2003, Time: 4:00 p.m., Location: Fine Hall 214
Abstract: Nerve cells communicate to one another across synapses. The receiver encodes this message as a change in local, in space and time, conductance. This change engenders a postsynaptic change in potential that actively diffuses through the dendritic tree and eventually may lead to the firing of a nervous impulse which may in turn lead to a long term change in the aforementioned synaptic conductance. To quantify this synaptic plasticity we propose a non invasive cocktail of optical imaging via voltage sensitive dyes and numerical determination of synapse location and conductance time course. In this talk we will focus on the mathematical and numerical study of the sideways Hodgkin-Huxley system that permits one to eavesdrop on synapses.
   
Mathematical Physics Brown Bag Lunch Talk
Topic: Strange Heat Flux in (an) Harmonic Networks
Presenter: Jean-Pierre Eckmann, Université de Genève
Date: Tuesday, November 25, 2003, Time: 12:30 p.m., Location: Jadwin 343
Abstract: In this work with E. Zabey, we produce examples of networks of harmonic springs in which heat flows in a counterintuitive fashion from certain cold reservoirs to hot reservoirs. And, even worse, there can be circulation of heat in such networks.
   
Mathematical Physics Seminar
Topic: Speed and Stability of Pattern-Forming Fronts
Presenter: Jean-Pierre Eckmann, Université de Genève
Date: Tuesday, November 25, 2003, Time: 4:30 p.m., Location: Jadwin A06
Abstract: I will discuss 2 papers concerning the pattern forming Swift-Hohenberg equation. One paper (with Pierre Collet) deals with a universal bound on the propagation speed, which tells us how fast patterns can invade empty space.  The other (with Guido Schneider) deals with a explanation of why these advancing patterns are actually stable under perturbation of the initial condition. This problem, which has long resisted proof has an astonishingly simple solution (at least in principle): The instabilities do not have "enough time" to really do any harm.
   
Algebraic Geometry Seminar
Topic: Simple Hironaka resolution
Presenter: Jaroslaw Wlodarczyk, Purdue University
Date: Tuesday, November 25, 2003, Time: 4:30 p.m., Location: Fine Hall 322
Abstract: Building upon works of O.Villamyor, Encinas-Villamayor and Bierstone-Milman we give a short proof of Hironaka resolution teorems. We put particular emphasis on canonicity and functoriality of the algorithm. Introduced here idea of "Homogenized ideals" gives apriorie canonicity of the resolution procedure and radically simplifies the proof.
   
Joint Institute for Advanced Study/Princeton University Complex Geometry Seminar
Topic: Hodge theory and Geometry, II
Presenter: Phillip Griffiths, Institute for Advanced Study
Date: Wednesday, November 26, 2003, Time: 1:00 p.m., Location: Fine Hall 401
   
Discrete Mathematics Seminar
Topic: TBA
Presenter:  Bela Bollobas, Memphis and Cambridge Universities
Date:  Wednesday, November 26, 2003, Time: 2:15 p.m., Location: Fine Hall 322
   

DECEMBER 1 - 5, 2003

   
Algebraic Geometry Seminar
Topic: TBA
Presenter: Sorin Popescu, Stony Brook
Date: Tuesday, December 2, 2003, Time: 4:30 p.m., Location: Fine Hall 322
   
Discrete Mathematics Seminar
Topic: How many ways can one draw a graph?
Presenter:  János Pach, New York University
Date:  Wednesday, December 3, 2003, Time: 2:15 p.m., Location: Fine Hall 322
   
Department Colloquium
Topic: Homological mirror symmetry for Fano surfaces
Presenter:  Denis Auroux, MIT
Date:  Wednesday, December 3, 2003, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: This talk will be an attempt, aimed at non-specialists, to explain the statement of the homological mirror symmetry conjecture, and describe a procedure for its verification on concrete examples, in a special case where essentially no understanding of symplectic topology is required.
   
Ergodic Theory and Statistical Mechanics Seminar
Topic: Critical percolation on the plane and conformal invariance of its scaling limit
Presenter: Vassilios Papathanakos, Princeton University
Date: Thursday, December 4, 2003, Time: 2:00 p.m., Location: Fine Hall 224
Abstract: We will present the recent result of S. Smirnov, who proved the conformal invariance of the scaling limit of critical percolation on the triangular lattice. After a quick review of the percolation model, we will discuss its scaling limit and the sense in which it is conformally invariant. Then, we will formulate the Smirnov theorem and describe details of its proof. Finally, we will give an update on recent developments on this topic
   
Joint Institute for Advanced Study/Princeton University Number Theory Seminar
Topic: TBA
Presenter: Manjul Bhargava, Princeton University
Date: Thursday, December 4, 2003, Time: 4:15 p.m., Location: Fine Hall 322
   

DECEMBER 8 - 12, 2003

   
Mathematical Physics Seminar
Topic: TBA
Presenter: Eugene Trubowitz, ETH, Zurich
Date: Tuesday, December 9, 2003, Time: 4:30 p.m., Location: Jadwin A06
   
Discrete Mathematics Seminar
Topic: TBA
Presenter:  Jeff Kahn, Rutgers University
Date:  Wednesday, December 10, 2003, Time: 2:15 p.m., Location: Fine Hall 322
   
Department Colloquium
Topic: TBA
Presenter:  Hillel Furstenberg, Yale University and Hebrew University of Jerusalem
Date:  Wednesday, December 10, 2003, Time: 4:30 p.m., Location: Fine Hall 314
   
Special Arithmetic Geometry and Number Theory Conference in Honor of Nicholas M. Katz for his 60th Birthday
Topics and Presenters:  See www.math.princeton.edu/katzconf/index.html for more information
Date:  Thursday, December 11, 2003 - Sunday, December 14, 2003
   
   
Ergodic Theory and Statistical Mechanics Seminar
Topic: Janossy densities in determinantal and pfaffian ensembles of random matrices
Presenter: Alexander Soshnikov, University of California at Davis
Date: Thursday, December 11, 2003, Time: 2:00 p.m., Location: Fine Hall 224
Abstract: In the first part of the talk I plan to give an introduction to detertminantal random point process and discuss some examples. The second part of the talk is devoted to the problem of the calculation of the Janossy densities in some special ensembles of random matrices, including the Laguerre (Wishart) ensemble.
   
Joint Columbia University/Courant Institute/Princeton University Differential Geometry Seminar
Topic: Collapsing and non-collapsing
Presenter: Jeff Cheeger, Courant Institute
Date: Friday, December 12, 2003, Time: 2:00 p.m., Location: Columbia University, New York
   
Joint Columbia University/Courant Institute/Princeton University Differential Geometry Seminar
Topic: Extremal K\"ahler metrics and applications
Presenter: Gang Tian, Princeton University
Date: Friday, December 12, 2003, Time: 3:30 p.m., Location: Columbia University, New York