Seminars and Colloquia by Series

Series: Other Talks
Wednesday, August 21, 2013 - 16:30 , Location: Klaus 1116W , Vijay V. Vazirani , School of Computer Science, Georgia Tech , Organizer:

Hosted by School of Computer Science.

Equilibrium computation is among the most significant additions to the theory of algorithms and computational complexity in the last decade - it has its own character, quite distinct from the computability of optimization problems. Our contribution to this evolving theory can be summarized in the following sentence: Natural equilibrium computation problems tend to exhibit striking dichotomies. The dichotomy for Nash equilibrium, showing a qualitative difference between 2-Nash and k- Nash for k > 2, has been known for some time. We establish a dichotomy for market equilibrium. For this purpose. we need to define the notion of Leontief-free functions which help capture the joint utility of a bundle of goods that are substitutes, e.g., bread and bagels. We note that when goods are complements, e.g., bread and butter, the classical Leontief function does a splendid job. Surprisingly enough, for the former case, utility functions had been defined only for special cases in economics, e.g., CES utility function. We were led to our notion from the high vantage point provided by an algorithmic approach to market equilibria. Note: Joint work with Jugal Garg and Ruta Mehta.
Series: Other Talks
Monday, April 29, 2013 - 17:00 , Location: Skiles 006 , Pedro Rangel , Georgia Tech , Organizer: Anton Leykin
(algebraic statistics reading seminar)
Series: Other Talks
Monday, April 29, 2013 - 15:05 , Location: Klaus 1116W , Maxim Raginsky , University of Illinois, Urbana-Champaign , Organizer: Prasad Tetali
The problem of quantifying the amount of information loss due to a random transformation (or a noisy channel) arises in a variety of contexts, such as machine learning, stochastic simulation, error-correcting codes, or computation in circuits with noisy gates, to name just a few. This talk will focus on discrete channels, where both the input and output sets are finite.  The noisiness of a discrete channel can be measured by comparing suitable functionals of the input and output distributions. For instance, if we fix a reference input distribution, then the worst-case ratio of output relative entropy (Kullback-Leibler divergence) to input relative entropy for any other input distribution is bounded by one, by the data processing theorem. However, for a fixed reference input distribution, this quantity may be strictly smaller than one, giving so-called strong data processing inequalities (SDPIs). I will show that the problem of determining both the best constant in an SDPI and any input distributions that achieve it can be addressed using logarithmic Sobolev inequalities, which relate input relative entropy to certain measures of input-output correlation. I will also show that SDPIs for Kullback-Leibler divergence arises as a limiting case of a family of SDPIs for Renyi divergence, and discuss the relationship to hypercontraction of Markov operators.
Series: Other Talks
Saturday, April 27, 2013 - 09:00 , Location: Klaus 1116 , Fan Chung Graham , University of California, San Diego , Organizer: Xingxing Yu
Emory University, the Georgia Institute of Technology and Georgia State University, with support from the National Security Agency and the National Science Foundation, are hosting a series of mini-conferences. The ninth in the series will be held at Georgia Tech on April 27-28, 2013. This mini-conference's featured speaker is Dr. Fan Chung Graham, who will give two one-hour lectures. There will be five one-hour talks and a number of half-hour talks given by other invited speakers. To register, please submit the registration form. Registration is free but is required.
Series: Other Talks
Wednesday, April 24, 2013 - 15:00 , Location: Klaus 1456 , Ruta Mehta , Indian Institute of Technology, Bombay , Organizer: Robin Thomas
The rank of a bimatrix game (A, B) is defined as the rank of (A+B). For zero-sum games, i.e., rank 0, Nash equilibrium computation reduces to solving a linear program. We solve the open question of Kannan and Theobald (2005) of designing an efficient algorithm for rank-1 games. The main difficulty is that the set of equilibria can be disconnected. We circumvent this by moving to a space of rank-1 games which contains our game (A, B), and defining a quadratic program whose optimal solutions are Nash equilibria of all games in this space. We then isolate the Nash equilibrium of (A, B) as the fixed point of a single variable function which can be found in polynomial time via an easy binary search. Based on a joint work with Bharat Adsul, Jugal Garg and Milind Sohoni.
Series: Other Talks
Monday, April 22, 2013 - 17:30 , Location: Skiles 006 , Charles Wang , Georgia Tech , Organizer: Anton Leykin
(algebraic statistics reading seminar)
Series: Other Talks
Monday, April 15, 2013 - 17:00 , Location: Skiles 006 , Josephine Yu , Georgia Tech , Organizer: Anton Leykin
(algebraic statistics reading seminar)
Series: Other Talks
Tuesday, April 9, 2013 - 09:00 , Location: Klaus 1116 , ARC Theory Day , Algorithms and Randomness Center, Georgia Tech , Organizer: Prasad Tetali
Algorithms and Randomness Center (ARC) Theory Day is an annual event that features hour-long lectures focusing on recent innovative results in theoretical computer science, spanning a wide array of topics several of which are inspired by practical problems. See the complete list of titles and times of talks.
Series: Other Talks
Monday, April 8, 2013 - 15:00 , Location: Klaus 1116 , Avrim Blum , Carnegie Mellon University , Organizer: Prasad Tetali
Pricing and allocating goods to buyers with complex preferences in order to maximize some desired objective (e.g., social welfare or profit) is a central problem in Algorithmic Mechanism Design. In this talk I will discuss some particularly simple algorithms that are able to achieve surprisingly strong guarantees for a range of problems of this type. As one example, for the problem of pricing resources, modeled as goods having an increasing marginal extraction cost to the seller, a simple approach of pricing the i-th unit of each good at a value equal to the anticipated extraction cost of the 2i-th unit gives a constant-factor approximation to social welfare for a wide range of cost curves and for arbitrary buyer valuation functions. I will also discuss simple algorithms with good approximation guarantees for revenue, as well as settings having an opposite character to resources, namely having economies of scale or decreasing marginal costs to the seller.
Series: Other Talks
Friday, April 5, 2013 - 12:00 , Location: Student Center Ferst Place, Room 343 , Laurie McNeil , University of North Carolina , Organizer:

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