January 22, 2017
Fields Institute, 222 College Street, Toronto

PAST TALKS 2013-14

Public Lectures
Avner Magen Memorial Lectures

Fields-Perimeter Africa Postdoctoral Fellowship Lecture
March 19, 2014 at 2 p.m.
University of Abomey-Calavi, Benin and The Perimeter Institute
Master equation of correlation functions for tensorial group field theory (video of the talk) (slides)

In this talk we provide the closed equations that satisfy correlation functions of the rank 3 and 4 tensorial group field theory. Ward-Takahashi identities and Schwinger-Dyson equations are combined to establish a nonlinear integral equation for the two-point functions. In the 3D case the solution of this equation is given perturbatively at second order of the coupling constant. [arxiv 1401.2096 and forthcoming work].

Information about Dr. Samary

February 3, 2014 at 2 p.m.
STAN WAGON, Mathematics and Computer Science, Macalester College, St Paul Minnesota
Some Shocking Results in Mathematics (video of the talk)

Some results are so shocking that they defy belief. The talk will present several cases, from very elementary to very sophisticated, that illustrate this point. Examples presented will include: a modern interpretation of Hilbert's Hotel, Julia Robinson's surprising doctoral theorem about the rationals, a working model of a square wheel bike and a square-hole drill, and an impossible construction using regular tetrahedra.

June 6, 2014 at 11 a.m.
KONSTANTINOS GEORGIOU, University of Waterloo
Lift-and-project systems for combinatorial optimization problems; More than a decade of fascinating positive and negative results
(Video of the talk)

A popular paradigm in approximation algorithms for intractable combinatorial optimization problems is to first formulate the problem at hand as an integer program and then relax the integrality condition, giving rise to a tractable optimization problem. At the same time, the relaxation introduces discrepancy between the true optimum and the optimal solution of the relaxation, which can be properly quantified so as to correspond to the approximability one can achieve for the combinatorial problem. In order to cope with this discrepancy, a number of systematic procedures, known as lift-and-project systems, have been introduced that effectively tighten the relaxations and that enjoy appealing algorithmic properties.

Over the last decade, numerous positive and negative results have been established for lift-and-project systems and for various intractable optimization problems. On one hand, the best algorithms known for a series of optimization problems are due to lift-and-project systems. On the other hand, there is evidence that the limitations of lift-and-project systems as tools in approximation algorithms indicate the actual hardness for a number of intractable optimization problems.

In this talk I will review the area of lift-and-project systems. After a self-contained and high level introduction to the systems, I will discuss a number of applications, trying to distill the main ingredients of this algorithmic tool. At the same time I will try to expose its weaknesses along with the challenges that are involved in showing positive and negative results. The exposition will be based on numerous fascinating results of the last decade or so..

June 6, 2013
Bernard Chazelle
, Princeton University
(Video of the talk)
Why Algorithms Are Poised to Become the Language of the Living World

May 25, 2012
Avi Wigderson, Institute for Advanced Study

July 11, 2011
Avner Magen Memorial Lecture Day

Ben-Gurion University

May 27, 2011
Nati Linial, The Hebrew University of Jerusalem
What is high dimensional combinatorics?
held at Massey College



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