  We review the basic steps leading to the construction of a Sinai-Ruelle-Bowen
(SRB) measure for an infinite lattice of weakly coupled expanding circle maps,
and we show that this measure has exponential decay of space-time correlations.
First, using the Perron-Frobenius operator, one connects the dynamical system
of coupled maps on a $d$-dimensional lattice to an equilibrium statistical
mechanical model on a lattice of dimension $d+1$. This lattice model is, for
weakly coupled maps, in a high-temperature phase, and we use a general, but
very elementary, method to prove exponential decay of correlations at high
temperatures.
