  A method is described for calculating corrections to the
Boltzmann/Chapman-Enskog analysis of lattice gases due to the buildup of
correlations. It is shown that renormalized transport coefficients can be
calculated perturbatively by summing terms in an infinite series. A
diagrammatic notation for the terms in this series is given, in analogy with
the Feynman diagrams of quantum field theory. This theory is applied to an
example lattice gas and shown to correctly predict experimental deviation from
the Boltzmann prediction.
