Ising Random Fields (2006)
These notes aim at giving the start of a self-contained mathematical
presentation of the construction and study of
Gibbs states of discrete spin systems on the lattice. For the sake of simplicity, we
focus on Ising-type models.
We start by describing the problem of constructing probability measures on infinite
configurations, discuss the Kolmogorov approach as well as the Dobrushin approach via specifications
(conditional probabilities). We then introduce the metric structure on configurations and
the notion of quasilocality. The topology of local convergence
on probability measures is introduced, and used to construct measures compatible
with a quasilocal specification.
We also discuss the Dobrushin uniqueness criterium.
Keywords: Infinite volume spin system, probability measure, specification,
topology of local convergence, quasilocal specification, Dobrushin uniqueness, Ising model.
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