Seminars and Colloquia by Series

Asymptotic properties of random matrices of long-range percolation model

Series
Stochastics Seminar
Time
Thursday, October 21, 2010 - 15:05 for 1 hour (actually 50 minutes)
Location
Skiles 002
Speaker
Slim AyadiSchool of Math, Georgia Tech
We study the spectral properties of matrices of long-range percolation model. These are N*N random real symmetric matrices H whose elements are independent random variables taking zero value with probability 1-\psi((i-j)/b), b\in \R^{+}, where \psi is an even positive function with \psi(t)<1 and vanishing at infinity. We show that under rather general conditions on the probability distribution of H(i,j) the semicircle law is valid for the ensemble we study in the limit N,b\to\infty. In the second part, we study the leading term of the correlation function of the resolvent G(z)=(H-z)^{-1} with large enough |Imz| in the limit N,b\to\infty, b=O(N^{\alpha}), 1/3<\alpha<1. We show that this leading term, when considered in the local spectral scale leads to an expression found earlier by other authors for band random matrix ensembles. This shows that the ensemble we study and that of band random matrices belong to the same class of spectral universality.

Public Lecture - Celebration of Mind - The Mathematics, Magic & Mystery of Martin Gardner

Series
Other Talks
Time
Thursday, October 21, 2010 - 11:00 for 1 hour (actually 50 minutes)
Location
Klaus 1456
Speaker
Colm MulcahySpelman College
Martin Gardner (1914-2010) "brought more mathematics to more millions than anyone else,"  according to Elwyn R. Berlekamp, John H. Conway & Richard K. Guy. Who was this man, how was he so influential, and will his legacy matter in the 22nd century? We'll try to answer these questions.This event is part of a one-day global celebration of the life of Martin Gardner. See www.g4g-com.org for information on Atlanta's Celebration of Mind party.

The Graph Removal Lemma

Series
Combinatorics Seminar
Time
Wednesday, October 20, 2010 - 15:05 for 1 hour (actually 50 minutes)
Location
Skiles 269
Speaker
Jacob FoxMath, MIT
Let H be a fixed graph with h vertices. The graph removal lemma states that every graph on n vertices with o(n^h) copies of H can be made H-free by removing o(n^2) edges. We give a new proof which avoids Szemeredi’s regularity lemma and gives a better bound. This approach also works to give improved bounds for the directed and multicolored analogues of the graph removal lemma. This answers questions of Alon and Gowers.

Polya sequences, gap theorems, and Toeplitz kernels

Series
Analysis Seminar
Time
Wednesday, October 20, 2010 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 269
Speaker
Mishko MitkovskiGeorgia Tech
A separated sequence of real numbers is called a Polya sequence if the only entire functions of zero type which are bounded on this sequence are the constants. The Polya-Levinson problem asks for a description of all Polya sequences. In this talk, I will present some points of the recently obtained solution. The approach is based on the use of Toeplitz operators and de Branges spaces of entire functions. I will also present some partial results about the related Beurling gap problem.

Orthogonal Polynomials and Beyond

Series
Research Horizons Seminar
Time
Wednesday, October 20, 2010 - 12:00 for 1 hour (actually 50 minutes)
Location
Skiles 171
Speaker
Lilian WongSchool of Mathematics - Georgia Institute of Technology

Please Note: Hosts: Yao Li and Ricardo Restrepo

This will be an expository talk on the study of orthogonal polynomials on the real line and on the unit circle. Topics include recurrence relations, recurrence coefficients and simple examples. The talk will conclude with applications of orthogonal polynomials to other areas of research.

Tropical and Berkovich analytic curves

Series
Tropical Geometry Seminar
Time
Wednesday, October 20, 2010 - 10:05 for 1 hour (actually 50 minutes)
Location
Skiles 114
Speaker
Matt BakerGeorgia Tech
We will discuss the relationship between a Berkovich analytic curve over a complete and algebraically closed non-Archimedean field and its tropicalizations, paying special attention to the natural metric structure on both sides. This is joint work with Sam Payne and Joe Rabinoff.

Self-avoiding walks and sampling in statistical physics models

Series
Probability Working Seminar
Time
Friday, October 15, 2010 - 15:05 for 1 hour (actually 50 minutes)
Location
Skiles 249
Speaker
Ricardo RestrepoSchool of Math, Georgia Tech
 We will discuss the role that self-avoiding walks play in sampling 'physical' models on graphs, allowing to translate  the complicated calculation of the marginals to a tree recurrence which, under the appropriate conditions (e.g. some form of 'spatial mixing'), reduces to a polynomial recurrence. This talk is mainly based on Dror Weitz' article "Counting independent sets up to the tree threshold". 

Non-commutative Geometry II

Series
Geometry Topology Working Seminar
Time
Friday, October 15, 2010 - 14:00 for 2 hours
Location
Skiles 171
Speaker
Jean BellissardGa Tech

Please Note: Note this is a 2 hour talk.

This series of lecture will try to give some basic facts about Noncommutative Geometry for the members of the School of Mathematics who want to learn about it. In the first lecture, the basics tools will be presented, (i) the philosophy and the notion of space, and (ii) the notion of C*-algebra, (iii) groupoids. As many examples as possible will be described to illustrate the purpose. In the following lectures, in addition to describing these tools more thoroughly, two aspects can be developed depending upon the wishes of the audience: A- Topology, K-theory, cyclic cohomology B- Noncommutative metric spaces and Riemannian Geometry.

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