On the Asymptotic Behaviour of Convolution Powers of Probabilities on Discrete Groups.
Singularities of the Green Function of a Random Walk on a Discrete Group.
Some Characterizations of AM- and AL-Spaces.
Restricting cuspidal representations of the group of automorphisms of a homogeneous tree
Let be a homogeneous tree in which every vertex lies on edges, where . Let be the group of automorphisms of , and let be the its subgroup , where is a local field whose residual field has order . We consider the restriction to of a continuous irreducible unitary representation of . When is spherical or special, it was well known that remains irreducible, but we show that when is cuspidal, the situation is much more complicated. We then study in detail what happens when the...
Property (T) and groups
We show that each group in a class of finitely generated groups introduced in [2] and [3] has Kazhdan’s property (T), and calculate the exact Kazhdan constant of with respect to its natural set of generators. These are the first infinite groups shown to have property (T) without making essential use of the theory of representations of linear groups, and the first infinite groups with property (T) for which the exact Kazhdan constant has been calculated. These groups therefore provide answers...
Random walks on the affine group of local fields and of homogeneous trees
The affine group of a local field acts on the tree (the Bruhat-Tits building of ) with a fixed point in the space of ends . More generally, we define the affine group of any homogeneous tree as the group of all automorphisms of with a common fixed point in , and establish main asymptotic properties of random products in : (1) law of large numbers and central limit theorem; (2) convergence to and solvability of the Dirichlet problem at infinity; (3) identification of the Poisson boundary...
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