Computer Science/Discrete Mathematics Seminar II

In a sequence of preprints M. Gromov introduced a new model of a random quotient of a finitely generated group and indicated that under favourable conditions the quotient groups should be non-trivial and satisfy Kazhdan's Property (T), both with high probability. The proof of the first assertion (using techniques of small cancellation theory) was completed by T. Delzant and Y. Ollivier. I will present a proof of the second assertion (analyzing the averaging properties of random walks). In this model quotients are constructed using a finite graph. Property (T) of the group arises from the spectral gap of that graph.