  We performed numerical experiments on a two-dimensional driven lattice gas,
which constitutes a simple stochastic nonequilibrium many-body model. In this
model, focusing on the behavior along the direction transverse to the external
driving force, we numerically measure transport coefficients and dynamical
fluctuations outside the linear response regime far from equilibrium. Using
these quantities, we find the validity of the Einstein relation, the Green-Kubo
relation and the fluctuation-response relation.
