Previous Special Year Seminar

The talk will be introductory. We will first explain what Kac-Moody groups are. These groups are defined by generators and relations, but they are better understood via their actions on buildings. The involved class of buildings is interesting since...

Consider an affine building of type $A_n$-tilde, which is a simplicial compex of dimension $n$. For $n=1$, this is a tree, which we will require to be homogeneous. Consider the space of complex valued functions on the vertices of the building, and...

We will describe some recent ergodic theorems for general families of averages on semisimple Lie groups, and explain how they can be used to 1) Solve the lattice point counting problem for general domains in the group, with explicit estimate of the...

Consider an affine building of type $A_n$-tilde, which is a simplicial compex of dimension $n$. For $n=1$, this is a tree, which we will require to be homogeneous. Consider the space of complex valued functions on the vertices of the building, and...

I will explain a conjectural generalisation of Ihara's lemma in the theory of modular forms to higher dimensional automorphic forms and sketch how this conjecture implies the Sato-Tate conjecture for rational elliptic curves with somewhere...

I will discuss the following theme: starting with an a priori Diophantine result (typical flavour: integer solutions to such-and-such equation are well-spaced) and turning it into an equidistribution-type statement on a homogeneous space. This (in...

Ramanujan graphs are grphs with optimal bounds on their eigenvalues. They play an important role in combinatorics and computer science. Their constructions in the late 80's used the work of Deligne and Drinfeld proving the Ramanujan conjecture for...