Seminars and Colloquia by Series

Compact Operators on Bergman Spaces

Series
Research Horizons Seminar
Time
Wednesday, October 24, 2012 - 12:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Brett Wick – Georgia Tech: School of Math
In this talk we will connect functional analysis and analytic function theory by studying the compact linear operators on Bergman spaces. In particular, we will show how it is possible to obtain a characterization of the compact operators in terms of more geometric information associated to the function spaces. We will also point to several interesting lines of inquiry that are connected to the problems in this talk. This talk will be self-contained and accessible to any mathematics graduate student.

Rigidity of Isometric Embeddings

Series
Research Horizons Seminar
Time
Wednesday, October 17, 2012 - 12:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Mohammad Ghomi – Georgia Tech - School of Math
One of the most outstanding problems in differential geometry is concerned with flexibility of closed surface in Euclidean 3-space: Is it possible to continuously deform a smooth closed surface without changing its intrinsic metric structure? In this talk I will give a quick survey of known results in this area, which is primarily concerned with convex surfaces, and outline a program for studying the general case.

Nonlinear Landau Damping and Inviscid Damping

Series
Research Horizons Seminar
Time
Wednesday, October 3, 2012 - 12:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Zhiwu Lin – Georgia Tech, School of Math
Consider electrostatic plasmas described by Vlasov-Poisson with a fixed ion background. In 1946, Landau discovered the linear decay of electric field near a stable homogeneous state. This phenomena has been puzzling since the Vlasov-Poisson system is time reversible and non-dissipative. The nonlinear Landau damping was proved for analytic perturbations by Mouhot and Villani in 2009, but for general perturbations it is still largely open. I will discuss some recent results with C. Zeng on the failure of nonlinear daming in low regularity neighborhoods and a regularity threshold for the existence of nontrivial invariant structures near homogeneous states. A related problem to be discussed is nonlinear inviscid damping of Couette flow, for which the linear decay was first observed by Orr in 1907.

Ends of Nonpositively Curved Manifolds

Series
Research Horizons Seminar
Time
Wednesday, September 26, 2012 - 12:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Igor Belegradek – Georgia Tech, School of Math
In the talk we will start from examples of open surfaces, such as the complex plane minus a Cantor set, review their classification, and then move to higher dimensions, where we discuss ends of manifolds in the topological setting, and finally in the geometric setting under the assumption of nonpositive curvature.

Orthogonal Polynomials and Random Matrices

Series
Research Horizons Seminar
Time
Wednesday, September 12, 2012 - 12:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Doron Lubinsky – School of Mathematics, Georgia Tech
Orthogonal polynomials turn out to be a useful tool in analyzing random matrices. We present some old and new aspects.

Circle Orders

Series
Research Horizons Seminar
Time
Wednesday, September 5, 2012 - 13:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
William Trotter – School of Mathematics, Georgia Tech
We survey research spanning more than 20 years on what starts out to be a very simple problem: Representing a poset as the inclusion order of circular disks in the plane. More generally, we can speak of spherical orders, i.e., posets which are inclusion orders of balls in R^d for some d. Surprising enough, there are finite posets which are not sphere orders. Quite recently, some elegant results have been obtained for circle orders, lending more interest to the many open problems that remain.

Sparse and low rank estimation problems

Series
Research Horizons Seminar
Time
Wednesday, April 18, 2012 - 12:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Vladimir Koltchinskii – Georgia Tech
Recently, there has been a lot of interest in estimation of sparse vectors in high-dimensional spaces and large low rank matrices based on a finite number of measurements of randomly picked linear functionals of these vectors/matrices. Such problems are very basic in several areas (high-dimensional statistics, compressed sensing, quantum state tomography, etc). The existing methods are based on fitting the vectors (or the matrices) to the data using least squares with carefully designed complexity penalties based on the $\ell_1$-norm in the case of vectors and on the nuclear norm in the case of matrices. Proving error bounds for such methods that hold with a guaranteed probability is based on several tools from high-dimensional probability that will be also discussed.

Elasto-Capillarity

Series
Research Horizons Seminar
Time
Wednesday, April 11, 2012 - 12:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
John McCuan – Georgia Tech
Classical mathematical capillarity theory has as its foundation variational methods introduced by Gauss. There was a heuristic explanation given earlier by Thomas Young, and his explanations did have quantitative scientific content. Due partially to their simplistic nature, the explanations of Young live on today in engineering textbooks, though in certain cases it has been pointed out that they lead to anomolous predictions (which are effectively avoided in the Gaussian variational framework). I will discuss a fundamentally new direction in mathematical capillarity which is motivated by an effort to harmonize the heuristic and rigorous elements of the theory and has other important applications as well.

Two applications of Riemannian geometry: Thermal stresses in solid mechanics and density preserving maps in machine learning.

Series
Research Horizons Seminar
Time
Wednesday, April 4, 2012 - 12:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Arkadaş Özakın – Georgia Tech Research Institute
I will present two "real life" applications of Riemannian geometry,one in the field of continuum mechanics, another in the field ofmachine learning (nonlinear dimensionality reduction). I will providequick introductions in order to make the talk accessible to anaudience with no background in either field.

From birational invariants to elections

Series
Research Horizons Seminar
Time
Wednesday, March 28, 2012 - 12:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Anton Leykin – Georgia Tech
This talk will traverse several topics in singularity theory, algebraic analysis, complex analysis, algebraic geometry, and statistics. I will outline effective methods to compute the log canonical threshold, a birational invariant of an algebraic variety, as well as its potential statistical applications.

Pages