Seminars and Colloquia by Series

Series: Other Talks
Monday, November 30, 2015 - 15:05 , Location: Howey L3 , Kenneth Showalter , West Virginia University , Organizer:

Hosted by Roman Grigoriev, School of Physics

We have studied large, heterogeneous populations of discrete chemical oscillators (~100,000) to characterize two different types of density-dependent transitions to synchronized behavior, a gradual Kuramoto synchronization and a sudden quorum sensing synchronization. We also describe the formation of phase clusters, where each cluster has the same frequency but is phase shifted with respect to other clusters, giving rise to a global signal that is more complex than that of the individual oscillators. Finally, we describe experimental and modeling studies of chimera states and their relation to other synchronization states in populations of coupled chemical oscillators.
Series: Other Talks
Monday, November 23, 2015 - 11:05 , Location: Skiles 006 , Sergey Bobkov , University of Minnesota, Minneapolis , Organizer: Prasad Tetali
We will discuss an extension of the entropy power inequality in terms of the Renyi entropy to sums of independent random vectors (with densities). Joint work with G. Chistyakov.
Series: Other Talks
Sunday, November 15, 2015 - 09:00 , Location: Skiles 006 , Noga Alon , Tel Aviv University and IAS, Princeton , Organizer: Xingxing Yu

Second featured lecture in the Atlanta Lecture Series in Combinatorics and Graph Theory mini-conference

The study of graphs with high girth and high chromatic number had a profound influence on the history of Combinatrics and Graph Theory, and led to the development of sophisticated methods involving tools from probability, topology, number theory, algebra and combinatorics. I will discuss the topic focusing on a recent new explicit construction of graphs (and hypergraphs) of high girth and high chromatic number, in joint work with Kostochka, Reiniger, West and Zhu.
Series: Other Talks
Saturday, November 14, 2015 - 13:00 , Location: Skiles 006 , Noga Alon , Tel Aviv University and IAS, Princeton , Organizer: Xingxing Yu

First featured lecture in the Atlanta Lecture Series in Combinatorics and Graph Theory mini-conference

I will describe several old and new applications of topological and algebraic methods in the derivation of combinatorial results. In all of them the proofs provide no efficient solutions for the corresponding algorithmic problems.
Series: Other Talks
Monday, October 26, 2015 - 13:30 , Location: Skiles 168 , Raphael Hauser , Mathematical Institute, University of Oxford , Organizer: Heinrich Matzinger
We propose a term structure power price model that, in contrast to widely accepted no-arbitrage based approaches, accounts for the non-storable nature of power. It belongs to a class of equilibrium game theoretic models with players divided into producers and consumers. The consumers' goal is to maximize a mean-variance utility function subject to satisfying an inelastic demand of their own clients (e.g households, businesses etc.) to whom they sell the power. The producers, who own a portfolio of power plants each defined by a running fuel (e.g. gas, coal, oil...) and physical characteristics (e.g. efficiency, capacity, ramp up/down times...), similarly, seek to maximize a mean-variance utility function consisting of power, fuel, and emission prices subject to production constraints. Our goal is to determine the term structure of the power price at which production matches consumption. We show that in such a setting the equilibrium price exists and discuss the conditions for its uniqueness. The model is then extended to account for transaction costs and liquidity considerations in actual trading. Our numerical simulations examine the properties of the term structure and its dependence on various model parameters. We then further extend the model to account for the startup costs of power plants. In contrast to other approaches presented in the literature, we incorporate the startup costs in a mathematically rigorous manner without relying on ad hoc heuristics. Through numerical simulations applied to the entire UK power grid, we demonstrate that the inclusion of startup costs is necessary for the modeling of electricity prices in realistic power systems. Numerical results show that startup costs make electricity prices very spiky. In a final refinement of the model, we include a grid operator responsible for managing the grid. Numerical simulations demonstrate that robust decision making of the grid operator can significantly decrease the number and severity of spikes in the electricity price and improve the reliability of the power grid.
Series: Other Talks
Monday, October 26, 2015 - 09:05 , Location: Student Center Theater, Georgia Tech , Various speakers , Georgia Tech , Organizer:
The workshop will be held from Monday October 26 - Wednesday October 28, 2015. The purpose of this workshop is to promote communication among the many mathematical and engineering communities currently researching polytopal discretization methods for the numerical approximation of solutions of partial differential equations. A variety of distinct polytopal element methods (POEMs) have been designed to solve the same types of problems, but a workshop-type environment is required to foster a community-wide understanding of the comparative advantages of each technique and to develop a set of ‘best practices’ in regards to implementation. Registration is required.
Series: Other Talks
Friday, October 23, 2015 - 16:30 , Location: Room 208 Emory Math and Science Center , Valery Alexeev , University of Georgia , Organizer: Matt Baker
Friday October 23 through Sunday October 25 Emory will host the Georgia Algebraic Geometry symposium featuring the following invited speakers: Valery Alexeev (University of Georgia); Brian Conrad (Stanford University); Brian Lehman (Boston College); Max Lieblich (University of Washington); Alexander Merkurjev (UCLA); Alena Pirutka (Ecole Polytechnique); Aaron Pixton (Harvard University); Tony Varilly-Alvarado (Rice University); Olivier Wittenberg (CNRS - Ecole Normale Superieure).
Series: Other Talks
Wednesday, October 21, 2015 - 17:00 , Location: Skies 006 , Inoel Popescu , Georgia Tech , Organizer:
This is the fourth meeting in a series of a reading seminars. In this lecture we will analyze the distribution of the eigenvalues of GUE ensembles.  We will use Hermite polynomials to get very concrete computations.  This way we will recover the semicircular law and we will also discuss a little bit the top eigenvalue. 
Series: Other Talks
Monday, October 5, 2015 - 19:00 , Location: President's Suites C&D (Bill Moore Student Success Center First Level) , Amir Dembo , Stanford University , Organizer: Prasad Tetali

Light refreshments at 6:30pm

Theoretical models of disordered materials yield precise predictions about the efficiency of communication codes and the typical complexity of certain combinatorial optimization problems. The underlying common structure is that of many discrete variables, whose interaction is represented by a random 'tree like' sparse graph. We review recent progress in proving such predictions and the related algorithmic insights gained from it. This talk is based on joint works with Andrea Montanari, Allan Sly and Nike Sun.
Series: Other Talks
Friday, September 25, 2015 - 14:00 , Location: Skiles 006 , Mohammad Ghomi , School of Mathematics, Georgia Tech , Organizer: Mohammad Ghomi
All students interested in graduate studies in the School of Math are invited to attend the "prospective student day." This event will offer the opportunity to hear about our graduate degree options, requirements for admission, as well as meet our Faculty and current graduate students. Prospective students from underrepresented groups in the Mathematical Sciences and students from the Atlanta area are particularly encouraged to attend. If you plan to attend, please send your name, the year you plan to graduate, and the college you are attending to dgs@math.gatech.edu. See the schedule for more details.

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