Previous Special Year Seminar

In the study of some dynamical systems, the limsup set of a sequence of measurable sets is often of interest. The shrinking targets and recurrence are two of the most commonly studied problems that concern limsup sets. However, the zero-one laws for...

A famous conjecture of Littlewood states that the Fourier transform of every set of N integers has $l^1$ norm at least log(N), up to a constant multiplicative factor. This was proved independently by McGehee-Pigno-Smith and Konyagin in the 1980s...

In model theory Fraisse limits are certain highly homogeneous countable structures -- examples include the rational numbers as the unique dense linear order without endpoints, and the Rado graph as the "unique infinite random graph".  I will discuss...

A word on d letters is an element of the free group of rank d, say, with basis x_1,…,x_d. Given a word w=w(x_1,…,x_d) on d letters, for every group G, there is a word map w:G^d—> G given by substituting the x_i’s with elements of G. We say that a...

A number is called y-smooth if all of its prime factors are bounded above by y. The set of y-smooth numbers below x forms a sparse subset of the integers below x as soon as x is sufficiently large in terms of y. If f_1, …, f_r \in Z[x_1,…,x_s] is a...

In these two talks, I will discuss the structure of certain varieties that depend functorially on the choice of a finite-dimensional vector space. Examples include the variety of d-way tensors of "slice rank" at most k and the variety of degree-d...

The restriction conjecture, one of the most central problems in harmonic analysis, studies the Fourier transform of functions defined on curved surfaces; specifically, it claims that the level sets of such Fourier transforms are relatively small...

In these two talks, I will discuss the structure of certain varieties that depend functorially on the choice of a finite-dimensional vector space. Examples include the variety of d-way tensors of "slice rank" at most k and the variety of degree-d...

Given a topological dynamical system $(X,T)$ a bounded sequence $(a_n)$ and $f\in C(X)$ we are interested in the asymptotic behavior of $$\frac{1}{\sum_{n\leq N}|a_n|}\sum_{n\leq N}a_nf(T^nx)$$