| Résume | We will discuss, first, how to construct automorphisms of countable/separable saturated models (and, more interestingly, pairs of automorphisms) that act "very freely" on the structure, in a sense given by stability theory. Then we will see how to use this to show that automorphism groups of aleph_0-categorical metric structures have Kazhdan's Property (T), which roughly means that their unitary actions on Hilbert spaces do not have almost invariant vectors in non-trivial ways. |
