Events and Activities

Explore current and upcoming events and activities happening at the Institute for Advanced Study.

Jan
25
2021

Computer Science/Discrete Mathematics Seminar I

An Improved Exponential-Time Approximation Algorithm for Fully-Alternating Games Against Nature
11:15am|Remote Access - see Zoom link below

"Games against Nature" [Papadimitriou '85] are two-player games of perfect information, in which one player's moves are made randomly. Estimating the value of such games (i.e., winning probability under optimal play by the strategic player) is an...

Jan
26
2021

Computer Science/Discrete Mathematics Seminar II

Log-concave polynomials in theory and applications
10:30am|Simonyi 101 and Remote Access

A polynomial with nonnegative coefficients is strongly log-concave if it and all of its derivatives are log-concave as functions on the positive orthant. This rich class of polynomials includes many interesting examples, such as homogeneous real...

Jan
27
2021

Stability and Testability

Stability of amenable groups via ergodic theory
Arie Levit
11:00am|Remote Access
I will describe how basic ergodic theory can be used to prove that certain amenable groups are stable. I will demonstrate our method by showing that lamplighter groups are stable. Another uncountably infinite family to which our method applies are...
Feb
01
2021

Computer Science/Discrete Mathematics Seminar I

Graph Density Inequalities, Sums of Squares and Tropicalization
Annie Raymond
11:15am|Remote Access - see Zoom link below

Establishing inequalities among graph densities is a central pursuit in extremal graph theory. One way to certify the nonnegativity of a graph density expression is to write it as a sum of squares or as a rational sum of squares. In this talk, we...

Feb
03
2021

Stability and Testability

Permutation stability of Grigorchuk groups
Tianyi Zheng
11:00am|Remote Access
A recent result of Becker, Lubotzky and Thom characterizes, for amenable groups, permutation stability in terms of co-soficity of invariant random subgroups (IRS). We will explain that for a class of amenable groups acting on rooted trees, including...
Feb
10
2021

Stability and Testability

Non-amenable groups admitting no sofic approximation by expander graphs
11:00am|Remote Access
We show that the direct product of an infinite, finitely generated Kazhdan Property (T) group and a finitely presented, not residually finite amenable group admits no sofic approximation by expander graphs. Joint work with Andreas Thom.