Description: In order to solve research problems of systems with a large number of states proposed decomposition approach. The method, which allows calculating the rational state groups. Consider the particular case of systems with two-dimensional analysis of the set of possible states. Substantiates the rational strategy of decomposition of a complex system, the functioning of which is described by the two-dimensional fully accessible Markov graph.
Keywords: system with a large number of states, decomposition, rational calculation of the number of groups, the computational procedure, evaluation of the effectiveness of decomposition procedures