Seminars and Colloquia by Series

Binary Black Hole Simulations - Mission Accomplished(?)

Series
CDSNS Colloquium
Time
Monday, February 2, 2009 - 16:30 for 2 hours
Location
Skiles 255
Speaker
Pablo Laguna – School of Physics, Georgia Tech
I will review results from binary black hole simulations and the role that these simulations have in astrophysics and gravitational wave observations. I will then focus on the mathematical and computational aspects of the recent breakthroughs in numerical relativity that have made finding binary black hole solutions to the Einstein field equations an almost routine exercise.

Reversibility and duality of SLE

Series
Job Candidate Talk
Time
Monday, February 2, 2009 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 255
Speaker
Dapeng Zhan – Yale University
Stochastic Loewner evolution (SLE) introduced by Oded Schramm is a breakthrough in studying the scaling limits of many two-dimensional lattice models from statistical physics. In this talk, I will discuss the proofs of the reversibility conjecture and duality conjecture about SLE. The proofs of these two conjectures use the same idea, which is to use a coupling technique to lift local couplings of two SLE processes that locally commute with each other to a global coupling. And from the global coupling, we can clearly see that the two conjectures hold.

Gabor Schauder bases and the Balian-Low Theorem

Series
Analysis Seminar
Time
Monday, February 2, 2009 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 255
Speaker
Chris Heil – School of Mathematics, Georgia Tech
The Balian-Low Theorem is a strong form of the uncertainty principle for Gabor systems that form orthonormal or Riesz bases for L^2(R). In this talk we will discuss the Balian-Low Theorem in the setting of Schauder bases. We prove that new weak versions of the Balian-Low Theorem hold for Gabor Schauder bases, but we constructively demonstrate that several variants of the BLT can fail for Gabor Schauder bases that are not Riesz bases. We characterize a class of Gabor Schauder bases in terms of the Zak transform and product A_2 weights; the Riesz bases correspond to the special case of weights that are bounded away from zero and infinity. This is joint work with Alex Powell (Vanderbilt University).

Duality exact sequences in contact homology

Series
Geometry Topology Seminar
Time
Monday, February 2, 2009 - 13:00 for 1 hour (actually 50 minutes)
Location
Skiles 269
Speaker
John Etnyre – School of Mathematics, Georgia Tech
I will discuss a "duality" among the linearized contact homology groups of a Legendrian submanifold in certain contact manifolds (in particular in Euclidean (2n+1)-space). This duality is expressed in a long exact sequence relating the linearized contact homology, linearized contact cohomology and the ordinary homology of the Legendrian submanifold. One can use this structure to ease difficult computations of linearized contact homology in high dimensions and further illuminate the proof of cases of the Arnold Conjecture for the double points of an exact Lagrangian in complex n- space.

Poorly Conditioned Minors of Random Matrices

Series
Combinatorics Seminar
Time
Friday, January 30, 2009 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 255
Speaker
Kevin P. Costello – School of Mathematics, Georgia Tech
Part of Spielman and Teng's smoothed analysis of the Simplex algorithm relied on showing that most minors of a typical random rectangular matrix are well conditioned (do not have any singular values too close to zero). Motivated by this, Vershynin asked the question as to whether it was typically true that ALL minors of a random rectangular matrix are well conditioned. Here I will explain why that the answer to this question is in fact no: Even an n by 2n matrix will typically have n by n minors which have singular values exponentially close to zero.

Introduction to the h-principle

Series
Geometry Topology Working Seminar
Time
Friday, January 30, 2009 - 15:00 for 2 hours
Location
Skiles 269
Speaker
Mohammad Ghomi – Ga Tech
$h$-Principle consists of a powerful collection of tools developed by Gromov and others to solve underdetermined partial differential equations or relations which arise in differential geometry and topology. In these talks I will describe the Holonomic approximation theorem of Eliashberg-Mishachev, and discuss some of its applications including the sphere eversion theorem of Smale. Further I will discuss the method of convex integration and its application to proving the $C^1$ isometric embedding theorem of Nash. (Please note this course runs from 3-5.)

Introduction to the h-principle

Series
Other Talks
Time
Friday, January 30, 2009 - 15:00 for 2 hours
Location
Skiles 269
Speaker
Mohammad Ghomi – School of Mathematics, Georgia Tech

Please Note: Please note this course runs from 3-5.

h-Principle consists of a powerful collection of tools developed by Gromov and others to solve underdetermined partial differential equations or relations which arise in differential geometry and topology. In these talks I will describe the Holonomic approximation theorem of Eliashberg-Mishachev, and discuss some of its applications including the sphere eversion theorem of Smale. Further I will discuss the method of convex integration and its application to proving the C^1 isometric embedding theorem of Nash.

Simple Proof of the Law of Iterated Logarithm in Probability

Series
SIAM Student Seminar
Time
Friday, January 30, 2009 - 12:30 for 2 hours
Location
Skiles 269
Speaker
Jinyong Ma – School of Mathematics, Georgia Tech
I plan to give a simple proof of the law of iterated logarithm in probability, which is a famous conclusion relative to strong law of large number, and in the proof I will cover the definition of some important notations in probability such as Moment generating function and large deviations, the proof is basically from Billingsley's book and I made some.

Random trees and SPDE approximation

Series
Stochastics Seminar
Time
Thursday, January 29, 2009 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 269
Speaker
Yuri Bakhtin – School of Mathematics, Georgia Tech
This work began in collaboration with C.Heitsch. I will briefly discuss the biological motivation. Then I will introduce Gibbs random trees and study their asymptotics as the tree size grows to infinity. One of the results is a "thermodynamic limit" allowing to introduce a limiting infinite random tree which exhibits a few curious properties. Under appropriate scaling one can obtain a diffusion limit for the process of generation sizes of the infinite tree. It also turns out that one can approach the study the details of the geometry of the tree by tracing progenies of subpopulations. Under the same scaling the limiting continuum random tree can be described as a solution of an SPDE w.r.t. a Brownian sheet.

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