## Seminars and Colloquia by Series

Tuesday, March 16, 2010 - 12:00 , Location: Skiles 255 , Luca Dieci , Professor and Graduate Coordinator, School of Mathematics , Organizer:

Hosted by: Huy Huynh and Yao Li

We will have a chance to spend some time together to discuss issues of relevance to the Graduate Program.  Sort of like a "Town Hall Meeting" of the graduate students and the graduate coordinator. There are some things that I need to communicate to all of you, but the format is otherwise unstructured, and I am seeking suggestions on things which you would like to see addressed.  So, please send me comments on things which you would like to see discussed and I will do my best to get ready for them. Thanks, Luca Dieci.
Tuesday, March 9, 2010 - 12:00 , Location: Skiles 255 , Heinrich Matzinger , Professor, School of Mathematics , Organizer:

Hosted by: Huy Huynh and Yao Li

The Scenery Reconstruction Problem consists in trying to reconstruct a coloring of the integers given only the observations made by a random walk. For this we consider a random walk S and a coloring of the  integers X. At time $t$ we observe the color $X(S(t))$. The coloring is i.i.d. and we show that given only the sequence of colors $$X(S(0)),X(S(1)),X(S(2)),...$$ it is possible to reconstruct $X$ up to translation and reflection. The solution depends on the property of the random walk and the distribution of the coloring. Longest Common Subsequences (LCS) are widely used in genetics. If we consider two sequences X and Y, then a common subsequence of X and Y is a string which is a subsequence of X and of Y at the same time. A Longest Common Subsequence of X and Y is a common subsequence of X and Y of maximum length. The problem of the asymptotic order of the flucutation for the LCS of independent random strings has been open for decades. We have now been able to make progress on this problem for several important cases. We will also show the connection to the Scenery Reconstruction Problem.
Tuesday, March 2, 2010 - 12:00 , Location: Skiles 255 , Michael Lacey , School of Math, Georgia Tech , Organizer:

Hosted by: Huy Huynh and Yao Li

The Hilbert transform is a foundational transform, with deep connections to electrical charge, and  analyticity.  The two weight inequality for the Hilbert transform' concerns the most general setting in which the Hilbert transform admits a (weighted) L^2 inequality.  We will give a couple of (surprising?) ways that this question arises.  And we will indicate the surprise that is behind the recent description of all setting in which the two weight inequality holds.
Tuesday, February 23, 2010 - 12:00 , Location: Skiles 255 , Prasad Tetali , Professor, School of Mathematics and School of Computer Science , Organizer:

Hosted by: Huy Huynh and Yao Li

Sampling from and approximately counting the size of a large set of combinatorial structures has contributed to a renaissance in research in finite Markov chains in the last two decades. Applications are wide-ranging from sophisticated card shuffles, deciphering simple substitution ciphers (of prison inmates in the California state prison), estimating the volume of a high-dimensional convex body, and to understanding the speed of Gibbs sampling heuristics in statistical physics. More recent applications include rigorous estimates on J.M. Pollard's (1979) classical Rho and Kangaroo algorithms  for the discrete logarithm problem in finite cyclic groups. The lecture will be a brief (mostly self-contained) introduction to the  Markov Chain Monte Carlo (MCMC) methodology and applications, and will include some open problems.
Tuesday, February 16, 2010 - 12:00 , Location: Skiles 255 , Doron Lubinsky , School of Mathematics, Georgia Tech , Organizer:

Hosted by: Huy Huynh and Yao Li

Orthogonal Polynomials and their generalizations have a great many applications in areas ranging from signal processing to random matrices to combinatorics. We outline a few of the connections, and present some possible Ph. D Problems
Tuesday, February 9, 2010 - 12:00 , Location: Skiles 255 , Ernie Croot , School of Math, Georgia Tech , Organizer:

Hosted by: Huy Huynh and Yao Li

Olof Sisask and myself have produced a new probabilistic technique for finding almost periods' of convolutions of subsets of finite groups.  In this talk I will explain how this has allowed us to give (just recently) new bounds on the length of the longest arithmetic progression in a sumset A+A.
Tuesday, February 2, 2010 - 12:00 , Location: Skiles 255 , Matt Baker , School of Math, Georgia Tech , Organizer:

Hosted by: Huy Huynh and Yao Li

I will discuss some theorems and conjectures in the relatively new field of arithmetic dynamics, focusing in particular on some methods from number theory which can be used to study the orbits of points in algebraic dynamical systems.
Tuesday, January 26, 2010 - 12:00 , Location: Skiles 255 , John McCuan , School of Math, Georgia Tech , Organizer:

Hosted by: Huy Huynh and Yao Li

In the preceeding talk, I outlined a framework for variational problems and some of the basic tools and results.  In this talk I will attempt describe several problems of current interest.
Wednesday, December 2, 2009 - 12:00 , Location: Skiles 171 , John McCuan , School of Mathematics, Georgia Tech , , Organizer:
I will describe several geometrical problems that arise from the minimization of some sort of integral functional and the basic relation between such minimization and partial differential equations. Then I will make some further comments on my favorite kind of such problems, namely those that have something to do with minimizing area of surfaces under various side conditions.
Wednesday, November 18, 2009 - 12:00 , Location: Skiles 269 , Drs. Ulmer, Harrell, and Wick , School of Mathematics, Georgia Tech , Organizer:
The Research Horizons seminar this week will be a panel discussion on the academic job market for mathematicians.  The discussion will begin with an overview by Doug Ulmer of the hiring process, with a focus on the case of research-oriented universities.  The panel will then take questions from the audience.  Professor Wick was hired last year at Tech, so has recently been on the students' side of the process.  Professor Harrell has been involved with hiring at Tech for many years and can provide a perspective on the university side of the process.