  We present a method which allows reduction of a size of a simulated system.
The method can be applied to any system where one can define a finite set of
possible states of the system and an elementary process which transforms one
state of the system to another. The method is based on the symmetry of the
system symmetry; we get classes of states, which can be used instead of states.
We present a detailed procedure for undirected/directed and/or
unweighted/weighted graphs. We show applications of the method for different
types of systems.
