2006-2007 seminars

Apr
17
2007

Computer Science/Discrete Mathematics Seminar II

Expanders in Number Theory
11:00am|S-101

Originally number theoretic methods were used to construct optimal (explicit) expanders. Recently combinatorial methods have been utalized in proving that certain number theoretic graphs are expanders. We will explain some uses of such expanders in...

Apr
16
2007

Computer Science/Discrete Mathematics Seminar I

Fully Polynomial Time Approximation Schemes for Stochastic Dynamic Programs
11:15am|S-101

We develop a framework for obtaining (deterministic) Fully Polynomial Time Approximation Schemes (FPTASs) for stochastic univariate dynamic problems with either convex or monotone single-period cost functions. Using our framework, we give the first...

Apr
10
2007

Computer Science/Discrete Mathematics Seminar II

Aggregating Inconsistent Information: Ranking and Clustering
10:30am|S-101

In the past 2 years there has been considerable progress in the algorithmic problem of combining rankings (permutations on a ground set of "candidates") into a consensus ranking. This problem dates back to the 18th century, when the French...

Apr
09
2007

Computer Science/Discrete Mathematics Seminar I

The Complexity of Nash Equilibria
Christos Papadimitriou
11:15am|S-101

In 1951 Nash proved that every game has a Nash equilibrium. The proof is non-constructive, reducing the existence of Nash equilibria to that of Brouwer fixpoints. Whether Nash equilibria can be computed efficiently had remained open. I shall outline...

Apr
03
2007

Computer Science/Discrete Mathematics Seminar II

Pseudo-Random Number Generation by Algebraic Means (continued)
10:30am|S-101

In the first talk I reviewed the basic properties of linear feedback shift registers and their analysis using generating functions and trace functions. I then defined feedback with carry shift registers (FCSRs) and began their analysis by N-adic...

Apr
02
2007

Computer Science/Discrete Mathematics Seminar I

Data-Powered Computing
11:15am|S-101

Traditional algorithm design is being challenged by the remarkable technological advances in data acquisition of recent years. Today's algorithms must often cope with data that is massive, noisy, uncertain, high-dimensional, nonuniformly priced...

Mar
27
2007

Computer Science/Discrete Mathematics Seminar II

Pseudo-Random Number Generation by Algebraic Means
11:30am|West Building Lecture Theatre

Linear feedback shift registers (or, equivalently, linear recurrences) have been studied in one form or another for at least 75 years. They have found a Myriad of applications in communications, cryptography, random number generation, and other...

Mar
26
2007

Computer Science/Discrete Mathematics Seminar I

Near-Optimal Algorithms for Maximum Constraint Satisfaction
Konstantin Makarychev
12:15pm|West Building Lecture Theatre

We present approximation algorithms for the maximum constraint satisfaction problem with k variables in each constraint (MAX k-CSP). Given a (1-epsilon) satisfiable 2CSP our first algorithm finds an assignment of variables satisfying a 1 - O(sqrt...

Mar
20
2007

Computer Science/Discrete Mathematics Seminar II

The Design and Analysis of Simple Algorithms: Part II
11:30am|S-101

In part I of this talk, we began a discussion of "simple algorithms" and restricted our attention to the priority algorithm model which models ``greedy-like'' algorithms. In Part II of this talk, we will extend the priority algorithm framework to...

Mar
19
2007

Computer Science/Discrete Mathematics Seminar I

A Cryptographic Study of Secure Internet Measurement
David Xiao
12:15pm|S-101

The Internet is an indispensable part of our information society, and yet its basic foundations remain vulnerable to simple attacks, and one area that remains especially susceptible to attack is routing. There have been increasing efforts in the...