Seminars Sorted by Series

What is...?

Oct
23
2025

What is...?

What is Property $\tau$
Alex Lubotzky
11:30am|Simonyi 101 and Remote Access

Property (T) was defined by Kazhdan in the 1960s, who used it to prove two conjectures of Selberg on lattices in high-rank Lie groups. Shortly after that, Margulis used it to construct expander graphs.

Property $\tau$ is a baby version of property (T...

Nov
05
2025

What is...?

What are... Entropy Methods in Combinatorics?
12:45pm|Simonyi 101 and Remote Access

The Shannon entropy of a discrete random variable quantifies the number of bits of information conveyed by sampling that variable. Although originally introduced in the context of information theory, techniques relying on Shannon entropy have been...

Nov
19
2025

What is...?

What is... a Non Local Game?
12:45pm|Simonyi 101 and Remote Access

In the 1930s, Einstein, Podolsky and Rosen devised the "EPR paradox", which shed light on a peculiar phenomenon in the mathematical modeling of quantum mechanics:  Very far apart particles can exhibit correlated behaviour, which seemed to suggest a...

Dec
10
2025

What is...?

What is... Harmonic Functions on Groups?
12:45pm|Simonyi 101 and Remote Access

Harmonic functions on groups are connected to many properties of the groups: algebraic, geometric, analytic, and probabilistic.
For some groups (or spaces), it can be a challenge even to determine whether harmonic functions of certain types—such as...

Dec
17
2025

What is...?

What is String Topology?
12:45pm|Simonyi 101 and Remote Access

Given two families of loops on a closed smooth manifold, one can concatenate the loops at the intersections points of these families to obtain a new family of loops. This is the Chas–Sullivan product on the homology of the free loop space of a...

Working Group on Algebraic Number Theory

Feb
07
2013

Working Group on Algebraic Number Theory

An Introduction to motives
2:00pm|Fine Hall 322

We review the construction of the triangulated categories of motives over a base scheme (following the method of Morel and Voevodsky). We then explain quickly the construction of various operations between these categories as well as some...