Previous Special Year Seminar

Jan
31
2006

Lie Groups, Representations and Discrete Mathematics

Paley Graphs and the Combinatorial Topology of the Bruhat Decomposition
Ron Livnè
2:00pm|S-101

Paley graphs are well-known combinatorial objects which have many interesting properties. Many of these properties come from their symmetry under the automorphisms x-->ax+b of the affine line over a finite field F with q elements (q=4m+1). We...

Jan
27
2006

Arithmetic Homogeneous Spaces

Counting Representations of Arithmetic Groups
Alex Lubotzky
11:00am|S-101

Given a higher rank arithmetic group (E.g. SL(3,Z)) it has r(n) complex irreducible representations of degree n. We will study the the rate of growth of r(n), the associated zeta function SUM(r(n)n^(-s)), its Euler factorisation etc. Some...

Jan
24
2006

Lie Groups, Representations and Discrete Mathematics

The Classification of Finite Simple Groups: Aspects of the Second Generation Proof
Inna Korchagina
2:00pm|S-101

The classification of finite simple groups is widely acknowledged to be one of the major results in modern mathematics. The successful completion of its proof was announced in the early 1980's by Daniel Gorenstein. The original proof occupied...

Jan
17
2006

Lie Groups, Representations and Discrete Mathematics

Linear Representations and Arithmeticity of Lattices in Products of Trees
2:00pm|S-101

Closed subgroups of the automorphism group of a tree which acts locally primitively have a rich structure theory. Combined with superrigidity for irreducible lattices in products of trees such that the projection in each factor is locally primitive...

Dec
20
2005

Lie Groups, Representations and Discrete Mathematics

Normal Subgroups of the Multiplicative Group of a Finite Dimensional Division Algebra, and Valuations
2:00pm|S-101

I will discuss a proof of the fact that given a finite dimensional division algebra D over an arbitrary field, any finite quotient of the multiplicative group D^* is solvable (joint work with Y.Segev and G.Seitz). Time permitting, I will also talk...

Dec
13
2005

Lie Groups, Representations and Discrete Mathematics

Hanoi Tower Groups, their Spectra and Growth of Diameters of Schreier Graphs
Rostislav Grigorchuk
2:00pm|S-101

We will show how self-similar groups H(k) generated by finite automata can be related to Hanoi Tower games on k=3,4,... pegs. Then we will consider the spectrum of a Schreier graph of Hanoi Group H(3), will show that the group is of branch type, and...