Current Seminars
updated 3/9/2005

   
MARCH 9 - MARCH 11, 2005
   
Discrete Mathematics Seminar
Topic: The exact Turán function of the generalized triangle
Presenter: 

Oleg Pikhurko, Carnegie Mellon University

Date:  Wednesday, March 9, 2005, Time: 2:15 p.m., Location: Fine Hall 224
Abstract: Click here
   
Operations Research and Financial Engineering Seminar
Topic: Lecture on Stochastic Control and Super-Replication
Presenter: 

Mete Soner, Koc University, Turkey

Date:  Wednesday, March 9, 2005, Time: 3:00 p.m., Location: Friend 004 (Bowl)
   
Department Colloquium
Topic: The distribution of values of zeta and $L$-functions
Presenter:  Kannan Soundararajan, University of Michigan
Date:  Wednesday, March 9, 2005, Time: 4:30 p.m., Location: Fine Hall 314
   
Ergodic Theory and Statistical Mechanics Seminar
Topic: Joinings of Cartan actions
Presenter:  Manfred Einsiedler, Princeton University
Date:  Thursday, March 10, 2005, Time: 2:00 p.m., Location: Fine Hall 322
Abstract: In joint work with E. Lindenstrauss we obtained a complete classifications of joinings of higher rank Cartan actions on locally homogeneous spaces. Unlike the case of torus actions, here there is no 'up to zero entropy part' in the classification -- every ergodic joining is algebraic. Previous results in that direction required additional assumptions. We will discuss the proof and a reformulation as an equidistribution - result.
   
Operations Research and Financial Engineering Seminar
Topic: Lecture on Stochastic Control and Super-Replication
Presenter: 

Mete Soner, Koc University, Turkey

Date:  Thursday, March 10, 2005, Time: 3:00 p.m., Location: Friend 004 (Bowl)
   
Topology Seminar
Topic: Diophantine approximations on negatively curved manifolds
Presenter:  Sa'ar-David Hersonsky, Princeton University
Date:  Thursday, March 10, 2005, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: Inspired by the theory of Diophantine approximation of a real (or complex) number by rational ones, we develop a theory of approximation of geodesic lines in a negatively curved Riemannian manifold. The talk will be a survey on some of our results: We prove a Dirichlet type theorem, define a Hurwitz type constant in terms of the lengths of closed geodesics, and a Khintchine-Sullivan type theorem on the Hausdorff measure of the geodesic lines starting from a cusp that are well approximated by cusp returning ones. This is a joint project with Frederic Paulin (ENS-Paris).
   
MARCH 14 - MARCH 18, 2005
   
Group Actions and Automorphic Forms Seminar
Topic: TBA
Presenter:  Thomas Ward, University of East Anglia (UK)
Date:  Tuesday, March 15, 2005, Time: 11:30 a.m., Location: Fine Hall PL
   
MARCH 21 - MARCH 25, 2005
   
PACM Colloquium
Topic: Finite frames and quantum detection
Presenter: 

John Benedetto, University of Maryland

Date:  Monday, March 21, 2005, Time: 4:00 p.m., Location: Fine Hall 214
Abstract: We discuss quantum measurement in terms of positive operator-valued measures (POMs). For any tight frame with frame constant 1 for a separable Hilbert space there is an associated POM. Our setup is d-dimensional Hilbert space H and frames for H consisting of N elements. H represents a physical system, and it is known that the state x of the system is in E, a set of N given possible states. The problem is to perform a measurement in order to determine x. This is equivalent to constructing a POM on the subsets of E with a natural probabilistic property. Because of the relationship with frames, the problem reduces to constructing a tight frame with frame constant 1 which minimizes a probability of detection functional defined in terms of E. A compactness argument shows the existence of a solution. We solve the problem using techniques from Lagrangian mechanics and properties of SO(N) with the goal of constructing solutions numerically from the resulting equations. Geometrically uniform and Grassmannian frames are natural background material. This is a collaboration with Andrew Kebo.
   
Geometric Analysis Seminar *** Please note special date, time and location
Topic: Dirichlet-to-Neumann map for Poincaré-Einstein metrics
Presenter:  Robin Graham, University of Washington, Seattle
Date:  Tuesday, March 22, 2005, Time: 4:00 p.m., Location: Fine Hall 1201
Abstract: This talk will describe an analogue of a Dirichlet to Neumann map for Poincar\'e-Einstein metrics, also known as asymptotically hyperbolic or conformally compact Einstein metrics. An explicit identification of the linearization of the map at the sphere will be given for even interior dimensions, together with applications to the structure of the map near the sphere and to a different proof of the positive frequency conjecture of LeBrun which was resolved by Biquard.
   
Algebraic Geometry Seminar
Topic: Hodge type, divisibility of eigenvalues of Frobenius and slopes
Presenter: 

H. Esnault, Essen

Date:  Tuesday, March 22, 2005, Time: 4:30 p.m., Location: Fine Hall 322
Abstract: We discuss Deligne's philosophy of the relation between Hodge filtration and congruences for points over finite fields. 1-st example: Lang-Manin conjecture: Fanos over finite field have points (via motivic cohomology) 2-st example: unequal characteristic: Hodge type vanishing in dim 2 over p-adic field implies points in the mod p-reduction. In higher dimension we have to replace the Hodge type condition by a coniveau condition. The theorem is based on Deligne's integrality theorem over a fintie field and its extesnion (jointly with him) over a local field. 3-rd example: slopes in rigid cohomology (joint with Berthelot-Bloch): 2 thetas divisors on an abelian variety over the finite field $\F_q$ have the same number of points mod q. The theorem relies on a theorem describing how to compute the slope $[0 \1[$ part of rigid cohomology. It has other applications, eg a vanishing theorem combining Serre's and Kodaira's vanihsing theorem in char. p.
   
Operations Research and Financial Engineering Seminar
Topic: Embracing statistical challenges in the information technology age
Presenter: 

Bin Yu, University of California, Berkeley

Date:  Tuesday, March 22, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad
Abstract: Information technology advances are making data collection possible in most if not all fields of science and engineering and beyond. Statistics as a scientific discipline is challenged and enriched by the new opportunities resulted from these high-dimensional data sets.   In this talk, I will use serveral research projects to demonstrate how these IT challenges are met by finding new applications of traditional statistical thinking and methods and by incorporating compression and computation considerations into statistical estimation. In particluar, I will cover cloud detection over the polar region, microarray image compression for statistical analysis, and L2 boosting as a computationally efficient method for sparse nonparametric regression model fitting.
   
Discrete Mathematics Seminar
Topic: Odd independent transversals are odd
Presenter: 

Tibor Szabo, ETH

Date:  Wednesday, March 23, 2005, Time: 2:15 p.m., Location: Fine Hall 224
Abstract: Click here
   
Department Colloquium
Topic: Evolution of adiabatic invariants
Presenter:  Dmitry Dolgopyat, University of Maryland
Date:  Wednesday, March 23, 2005, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: We survey recent results on averaging in the sytems with two time scales slow and fast with particular emphasis on the case when the fast motion is the simplest possible, namely, periodic.
   
Joint Analysis Seminar
Topic: TBA
Presenter: 

Susan Friedlander, IAS and University of Illinois at Chicago

Date:  Thursday, March 24, 2005, Time: 4:00 p.m., Location: Fine Hall 214
   
Topology Seminar
Topic: TBA
Presenter: 

Walter Neumann, Institute for Advanced Study and Columbia University

Date:  Thursday, March 24, 2005, Time: 4:30 p.m., Location: Fine Hall 314
   
Geometric Analysis Seminar
Topic: Global Well-Posedness of the Lagrangian Averaged Equations of Fluid Type
Presenter:  Congming Li, University of Colorado
Date:  Friday, March 25, 2005, Time: 3:00 p.m., Location: Fine Hall 314
Abstract: Here, we present some recent global existence results about theLagragian averaged 3-D Euler Equation. The global existence of the Lagrangian averaged 2D Boussinesq equations and the Lagrangian averaged 2D quasi geostrophic equations in finite Sobolev space in the absence of viscosity or dissipation will also be established. This is a joint work with T. Hou.
   
Ergodic Theory and Statistical Mechanics Seminar *** Please note special date and time
Topic: Averaging for systems with periodic fast motion
Presenter:  Dmitry Dolgopyat, University of Maryland
Date:  Friday, March 25, 2005, Time: 4:00 p.m., Location: Fine Hall 322
Abstract: For the systems with periodic fast motion the main deviations from the averaged motion appear near the resonances. There are two competing phenomena scattering at resonances and repulsion from them. In this talk we describe both mechanisms and the relations between them.
   
MARCH 28 - APRIL 1, 2005
   
PACM Colloquium
Topic: TBA
Presenter: 

Nick Duffield, AT&T

Date:  Monday, March 28, 2005, Time: 4:00 p.m., Location: Fine Hall 214
   
Group Actions and Automorphic Forms Seminar
Topic: TBA
Presenter:  Werner Müller, Bonn and the Institute for Advanced Study
Date:  Tuesday, March 29, 2005, Time: 11:30 a.m., Location: Fine Hall PL
   
Princeton University/Institute for Advanced Study Complex Geometry Seminar
Topic: Einstein metrics on Seifert fibered manifolds
Presenter: 

János Kollár, Princeton University

Date:  Tuesday, March 29, 2005, Time: 2:30 p.m., Location: Fine Hall 110
   
Algebraic Geometry Seminar
Topic: Arakelov inequalities and the uniformization of certain bounded symmetric domains
Presenter: 

E. Viehweg, Essen

Date:  Tuesday, March 29, 2005, Time: 4:30 p.m., Location: Fine Hall 322
Abstract: Let $Y$ be a non-singular projective manifold with an ample canonical sheaf, and let $V$ be a rational variation of Hodge structures of weight one on $Y$ with Higgs bundle $E^{1,0}+E^{0,1}$. If $Y$ is a curve the Arakelov Inequality says that $\mu(E^{1,0})-\mu(E^{0,1})$ is smaller than or equal to the degree of the canonical sheaf. The equality implies that $V$ is the tensor product of a unitary bundle and the rank two variation of Hodge structures given by a theta characteristic; moreover $Y$ is the Shimura curve corresponding to $V$. We will discuss similar inequalities for surfaces $Y$. Here the equality will imply that $Y$ is either a compact Hilbert modular surface, or a ball quotient, and again $V$ is the tensor product of a canonical uniformizing variation of Hodge structures with a unitary bundle. Most of the results extend to variation of Hodge structures over quasi projective manifolds with a "nice" compactification and partly to the higher dimensional case. (joint work with Kang Zuo).
   
Operations Research and Financial Engineering Seminar
Topic: TBA
Presenter: Kavita Ramanan, Carnegie Mellon University
Date:  Tuesday, March 29, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad
   
Discrete Mathematics Seminar
Topic: TBA
Presenter: 

David Gamarnik, IBM Research

Date:  Wednesday, March 30, 2005, Time: 2:15 p.m., Location: Fine Hall 224
   
Department Colloquium
Topic: Markoff spectrum, expanding properties, and spectral gap
Presenter:  Gregory Margulis, Yale University
Date:  Wednesday, March 30, 2005, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: The purpose of the talk is to explain how effective estimates for the Markoff spectrum in dimensions 3 and 4 can be obtained using expanding properties for the actions of semisimple Lie groups on the quotients by arithmetic subgroups. These expanding properties follow from the spectral gap for the Laplace operator.
   
Topology Seminar
Topic: Deformations of the Khovanov Homology
Presenter:  Jacob Rasmussen, Princeton University
Date:  Thursday, March 31, 2005, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: The Khovanov homology is a homological generalization of the Jones polynomial. The technique of deforming the definition of this theory was introduced by Lee and studied in the sl(n) case by Gornik. It has proven to be a very powerful one. In this talk I'll describe the space of possible deformations, and give some applications, both to computing the sl(n) theory and to better understanding its structure.
   
Geometry, Representation Theory, and Moduli Seminar
Topic: Positivity of Quasi-local Mass
Presenter:  Chiu-Chu Liu, Harvard University
Date:  Friday, April 1, 2005, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: Quasi-local mass is a quantity associated to a spacelike 2-surface in a four dimensional spacetime. Several definitions of quasi-local mass have been proposed. I will discuss the positivity of one particular quasi-local mass based on joint works with Shing-Tung Yau.
   
   
APRIL 4 - APRIL 8, 2005
   
PACM Colloquium
Topic: 33 Years of Bin Packing
Presenter: 

David Johnson, AT&T

Date:  Monday, April 4, 2005, Time: 4:00 p.m., Location: Fine Hall 214
Abstract: In the bin packing problem, one is given a list of 1-dimensional items and asked to pack them into a minimum number of unit-capacity bins. This was one of the first NP-hard problems to be studied from the "approximation algorithm" point of view, and over the years it has served as a laboratory for the study of new questions about approximation algorithms and the development of new techniques for their analysis. In this talk I present a brief survey of this history, covering worst-case, average-case, and experimental results. The latter have led to many interesting conjectures and theorems, as well as the new "sum-of-squares" algorithm for the problem.
   
Group Actions and Automorphic Forms Seminar
Topic: TBA
Presenter:  Dave Witte Morris,University of Lethbridge
Date:  Tuesday, April 5, 2005, Time: 11:30 a.m., Location: Fine Hall PL
   
Algebraic Geometry Seminar
Topic: Degenerations of del Pezzo surfaces
Presenter: 

P. Hacking, Yale University

Date:  Tuesday, April 5, 2005, Time: 4:30 p.m., Location: Fine Hall 322
   
Operations Research and Financial Engineering Seminar
Topic: Useful Bounds on the Expected Maximum of Correlated Normal Variables
Presenter: Andrew Ross, Lehigh University
Date:  Tuesday, April 5, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad
Abstract: We compute useful upper and lower bounds on the expected maximum of up to a few hundred correlated Normal variables with arbitrary means and variances. Two types of bounding processes are used: perfectly dependent Normal variables, and independent Normal variables, both with arbitrary mean values. The expected maximum for the perfectly dependent variables can be evaluated in closed form; for the independent variables, a single numerical integration is required. Higher moments are also available. We use mathematical programming to find parameters for the processes, so they will give bounds on the expected maximum, rather than approximations of unknown accuracy. Our original application is to the maximum number of people on-line simultaneously during the day in an infinite-server queue with a time-varying arrival rate. The upper and lower bounds are tighter than previous bounds, and in many of our examples are within 5 percent of each other.
   
Discrete Mathematics Seminar
Topic: The Nature of Partition Bijections
Presenter:  Igor Pak, MIT
Date:  Wednesday, April 6, 2005, Time: 2:15 p.m., Location: Fine Hall 224
Abstract: Click here
   
Topology Seminar
Topic: TBA
Presenter: 

Jeff Brock, Brown University

Date:  Thursday, April 7, 2005, Time: 4:30 p.m., Location: Fine Hall 314
   
Operations Research and Financial Engineering Seminar *** Please note special date, time, location
Topic: Columbia-Princeton Probability Day
Presenter: List of prospective speakers include:
Alain Bensoussan, University of Texas at Dallas
Hans Föllmer, Humboldt University, Germany
Albert N. Shiryaev, Steklov Mathematical Institute, Russian
Date:  Friday, April 8, 2005, Time: TBA, Location: TBA
   
APRIL 11 - APRIL 15, 2005
   
PACM Colloquium
Topic: TBA
Presenter: 

Pino Martin, Mechanical & Aerospace Engineering, Princeton University

Date:  Monday, April 11, 2005, Time: 4:00 p.m., Location: Fine Hall 214
   
Operations Research and Financial Engineering Seminar
Topic: TBA
Presenter: Albert N. Shiryaev, Steklov Mathematics Institute, Russia
Date:  Tuesday, April 12, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad
   
Department Colloquium
Topic: The Inverse Problem in Invariant Theory
Presenter:  Michael Larsen, Indiana University
Date:  Wednesday, April 13, 2005, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: The direct problem in invariant theory is to describe the category of representations of a given group. Its inverse is to extract information about a group from information about its representations. The prototypical result in this direction is Tannaka duality. The ultimate goal is to recognize compact Lie groups which appear in nature, where in practice one typically does not know the category of representations up to isomorphism.
   
Joint Analysis Seminar
Topic: TBA
Presenter:  Vladimir Sverak, University of Minnesota
Date:  Thursday, April 14, 2005, Time: 4:00 p.m., Location: Fine Hall 214
   
Topology Seminar
Topic: The Reduced Algebraic K-theory of Square-Zero Extensions by Free Modules
Presenter: 

Ayelet Lindenstrauss, Indiana University

Date:  Thursday, April 14, 2005, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: This talk is about joint work with Randy McCarthy (UIUC). We give a method for finding the completion at a prime p of the reduced (over A) K-theory of the square-zero extension of A by a free A-module of finite rank, $\tilde K(A \semiprod (A^{\oplus k}))^\wedge _p$. The calculation is carried out when $A$ satisfies a technical condition which (by work of Hesselholt and Madsen) is satisfied by perfect fields of characteristic $p$, and in that case generalizes the dual numbers ($k=1$) case which Hesselholt and Madsen calculate by different methods.
Our calculation uses an invariant we call $W(A;M)$, which can be thought of as a Witt ring of $A$ with coefficients in $M$, or alternatively as cyclic homology of $A$ with coefficients in $M$. By Goodwillie calculus methods, $\tilde K (A \semiprod M) \simeq W(A;M\otimes S1)$, so what we actually study is $W(A; A^{\oplus k}\otimes S1)$. The completion at $p$ is needed for a topological analog of breaking the Witt ring down into a product of $p$-Witt vectors.
   
APRIL 18 - APRIL 22, 2005
   
PACM Colloquium
Topic: TBA
Presenter: 

David Cai, New York University

Date:  Monday, April 18, 2005, Time: 4:00 p.m., Location: Fine Hall 214
   
Group Actions and Automorphic Forms Seminar
Topic: TBA
Presenter:  Alexander Gorodnik, Caltech
Date:  Tuesday, April 19, 2005, Time: 11:30 a.m., Location: Fine Hall PL
   
Algebraic Geometry Seminar
Topic: TBA
Presenter: 

Gordon Heier, Harvard University

Date:  Tuesday, April 19, 2005, Time: 4:30 p.m., Location: Fine Hall 322
   
Operations Research and Financial Engineering Seminar
Topic: Smoothly Truncated Stable Distributions, GARCH-Models, and Option Pricing
Presenter: 

Christian Menn, Cornell University

Date:  Tuesday, April 19, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad
Abstract: Click here
   
Discrete Mathematics Seminar
Topic: Clique-width for graph classes defined by forbidden four-vertex subgraphs
Presenter: 

Andreas Brandstaed, University of Rostock

Date:  Wednesday, April 20, 2005, Time: 2:15 p.m., Location: Fine Hall 224
Abstract: Click here
   
Department Colloquium
Topic: Probabilistic reasoning and Ramsey Theory
Presenter:  Benjamin Sudakov, Princeton University
Date:  Wednesday, April 20, 2005, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: "Ramsey Theory" refers to a large body of deep results in mathematics concerning the partition of large collections. Its underlying philosophy is captured succinctly by the statement that "In a large system complete disorder is impossible". Since the publication of the seminal paper of Ramsey in 1930, this subject has grown with increasing vitality, and is currently among the most active areas in Combinatorics. An important factor in the development of Ramsey Theory was the successful application of the so-called "Probabilistic Method". This method was initiated more than fifty years ago by Paul Erdos, and became one of the most powerful and widely used tools in Discrete Mathematics. In this talk I will describe some classical results of Ramsey Theory together with recent progress on some old questions of Erdos which was made using probabilistic arguments. I will also discuss the problem of converting existence arguments into deterministic constructions, in particular, the recent explicit constructions of Bipartite Ramsey graphs.
   
Topology Seminar
Topic: TBA
Presenter: 

Peter Kronheimer, Harvard University

Date:  Thursday, April 21, 2005, Time: 4:30 p.m., Location: Fine Hall 314
   
Geometric Analysis Seminar
Topic: The structure of singularities of mean curvature flow
Presenter:  Bruce Kleiner, University of Michigan
Date:  Friday, April 22, 2005, Time: 3:00 p.m., Location: Fine Hall 314
   
Geometry, Representation Theory, and Moduli Seminar
Topic: TBA
Presenter:  Maryam Mirzakhani, Princeton University
Date:  Friday, April 22, 2005, Time: 4:30 p.m., Location: Fine Hall 314
   
APRIL 25 - APRIL 29, 2005
   
PACM Colloquium
Topic: Discrete Denoising
Presenter: 

Sergio Verdu, Applied Mathematics and Electrical Engineering, Princeton University

Date:  Monday, April 25, 2005, Time: 4:00 p.m., Location: Fine Hall 214
Abstract:

Finite-alphabet signals corrupted by discrete noisy channels arise naturally in a wide range of applications spanning fields such as statistics, engineering, and computer science. Examples include DNA sequence analysis and processing, text correction, Hidden Markov model state estimation, and image denoising. While the field of filtering or denoising of continuous-alphabet signals has a long history, the field of discrete denoising has seen far less progress.

In many discrete denoising applications, a good model for the randomness of the noisy channel is known, whereas the statistical description of the noiseless signal is either unknown or too complex. It is therefore of considerable interest to pose the problem of discrete universal denoising where no knowledge exists about the statistics of the noiseless signal while the channel statistics are assumed known.

I will present the DUDE algorithm for discrete universal denoising which has linear complexity and attains universal optimality in a stochastic sense as well as a stronger semi-stochastic sense.

I will also show several DUDE-based algorithms for channel decoding of systematically encoded redundant data.

Joint work with E. Ordentlich, G. Seroussi, M. Weinberger and T. Weissman.

   
Operations Research and Financial Engineering Seminar
Topic: Stochastic Gradient Estimation
Presenter: 

Michael Fu, University of Maryland

Date:  Tuesday, April 26, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad
Abstract: We survey the methods of stochastic gradient estimation, including perturbation analysis, the likelihood ratio method, and weak derivatives. We illustrate the techniques using models in queueing, inventory, and finance. In the latter case, the methods can be used for  estimating the so-called Greeks, which are crucial for hedging, and also for pricing American-style options (derivatives with early exercise opportunities). Computational examples using the estimators in stochastic approximation algorithms are described.
   
Topology Seminar
Topic: TBA
Presenter:  Helmut Hofer, NYU
Date:  Thursday, April 28, 2005, Time: 4:30 p.m., Location: Fine Hall 314
   
Geometric Analysis Seminar
Topic: Ricci flow on locally homogeneous closed 4-manifolds
Presenter:  Peng Lu, University of Oregon
Date:  Friday, April 29, 2005, Time: 3:00 p.m., Location: Fine Hall 314
Abstract: We discuss the Ricci flow on homogeneous 4-manifolds. After list the classification these manifolds, we show that there are families of initial metrics such that we can diagonalize them and the Ricci flow preserves the diagonalization, then we analyze the long time behavior of these families.
   
MAY 9 - MAY 14, 2005
   
Operations Research and Financial Engineering Seminar
Topic: TBA
Presenter: Peter Bickel, University of California, Berkeley
Date:  Tuesday, May 10, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad