  We study the decoherence of two coupled spins that interact with a spin-bath
environment. It is shown that the connectivity and the coupling strength
between the spins in the environment are of crucial importance for the
decoherence of the central system. For the anisotropic spin-bath, changing the
connectivity or coupling strenghts changes the decoherence of the central
system from Gaussian to exponential decay law. The initial state of the
environment is shown to affect the decoherence process in a qualitatively
significant manner.
