### 2 mars 2006,
Jeffrey Steif (Chalmers): Statistical mechanical systems on complete
graphs, infinite exchangeability and finite extensions

**Abstract.**
We discuss the notion of infinite exchangeability in the context of
statistical mechanical systems. It turns out that many ferromagnetic systems
(like Ising, Potts and Heisenberg models)
can be extended to so-called infinite exchangeable processes.
For the antiferromagnetic Ising model, we obtain sharp
quantitative results on how much the system can be extended.
One approach for doing this is via a solution of a new type of moment
problem. This is joint work with Tom Liggett and Balint Toth.