  We study the relaxation process in a simple glass-former - the KA lattice gas
model. We show that, for this model, structural relaxation is due to slow
percolation of regions of co-operatively moving particles, which leads to
heterogeneous dynamics of the system. We find that the size distribution of
these regions is given by a power-law and that their formation is encoded in
the initial structure of the particles, with the memory of initial
configuration increasingly retained with increasing density.
