  The Zwanzig-Mori pro jection formalism is widely used in studying systems
with many degrees of freedom. Recently Xing and Kim used the pro jection
formalism and derived the generalized Langevin equations (GLEs) for a general
stochastic system not necessarily obeying detailed balance. In this study we
develop a numerical procedure to reconstruct the GLEs from data. Numerical
tests on two biological networks show remarkable agreement between the results
calculated from the reconstructed GLEs and those of full model simulations. We
suggest that the procedure can be applied in model reduction and a novel way of
nonlinear time series analysis.
