Previous Conferences & Workshops

Jan
30
2018

Locally Symmetric Spaces Seminar

Introduction to spherical varieties (1)
10:00am

I will give a brief introduction to spherical varieties. With a view towards understanding the geometry of the moment map, I'll talk about the local structure theorem for spherical varieties. More concretely, if X is a spherical G-variety and B a...

Jan
29
2018

Members’ Seminar

Symmetries of hamiltonian actions of reductive groups
2:00pm|S-101

Classical and quantum Hamiltonian actions of reductive groups, respectively, give rise to ubiquitous families of commuting flows and of commutative rings of operators. I will explain how a construction of Ngô (from the proof of the Fundamental Lemma...

Jan
29
2018

Computer Science/Discrete Mathematics Seminar I

Explicit, Epsilon-Balanced Codes Close to the Gilbert-Varshamov Bound
Amnon Ta-Shma
11:00am|S-101

I will show an explicit construction of a binary error correcting code with relative distance $\frac{1-\epsilon}{2}$ and relative rate $\epsilon^{2+o(1)}$. This comes close to the Gilbert-Varshamov bound that shows such codes with rate $\epsilon^2$...

Jan
25
2018

Theoretical Machine Learning Seminar

Prediction and Control of Linear Dynamical Systems
Cyril Zhang
12:15pm|White-Levy

Linear dynamical systems (LDSs) are a class of time-series models widely used in robotics, finance, engineering, and meteorology. I will present our "spectral filtering" approach to the identification and control of discrete-time LDSs with multi...

Jan
24
2018

Mathematical Conversations

Zeroes of Laplace eigenfunctions
6:00pm|White-Levy

The classical Liouville theorem claims that any positive harmonic function in $R^n$ is a constant function. Nadirashvili conjectured that any non-constant harmonic function in $R^3$ has a zero set of infinite area. The conjecture is true and we will...

Jan
23
2018

Locally Symmetric Spaces Seminar

Modular symbols and arithmetic
1:45pm|S-101

In these lectures, we will explore what insight can be gained into the arithmetic of Galois representations in a given dimension through the geometry of a higher-dimensional locally symmetric space near a boundary component. The starting point for...

Jan
23
2018

Computer Science/Discrete Mathematics Seminar II

A Constant-factor Approximation Algorithm for the Asymmetric Traveling Salesman Problem
Ola Svensson
10:30am|S-101

We give a constant-factor approximation algorithm for the asymmetric traveling salesman problem. Our approximation guarantee is analyzed with respect to the standard LP relaxation, and thus our result confirms the conjectured constant integrality...

Jan
22
2018

Members’ Seminar

On a conjecture for $p$-torsion in class groups of number fields
Lillian Pierce
2:00pm|S-101

This talk will survey ideas surrounding a conjecture in number theory about the structure of class groups of number fields. Each number field has associated to it a finite abelian group, the class group, and as long ago as Gauss, deep questions...

Jan
22
2018

Computer Science/Discrete Mathematics Seminar I

The Matching Problem in General Graphs is in Quasi-NC
Ola Svensson
11:00am|S-101

We show that the perfect matching problem in general graphs is in Quasi-NC. That is, we give a deterministic parallel algorithm which runs in polylogarithmic time on quasi-polynomially many processors. The result is obtained by a derandomization of...