  The relaxational behaviour of the bond-diluted two-dimensional Ising model
below the percolation threshold is studied using Monte Carlo techniques. The
non-equilibrium decay of the magnetization,M(t), and the relaxation of the
equilibrium spin-spin autocorrelation function, C(t), are monitored. The
behaviour of both C(t) and M(t) is found to satisfy the Kohlrausch law of a
stretched exponential with the same temperature-dependent exponent. The
Kohlrausch exponent does not appear to depend on the bond concentration. The
results indicate that we are not yet in the asymptotic regime, even when C(t)
and M(t) are less than 10^{-4}.
