The state is information needed from all preceding stages in order to make a decision in the current stage without reference to previous decisions made. It represents status information on the project at any point in time. Stages may be decomposed to finer detail, right down to activity level. The project may be subdivided into subprojects or stages. The choice where the subdivision occurs depends on the user and the nature of the project, but in principle any subdivision is possible. Associated with each stage is an objective function which evaluates the worth of each stage decision made from a range of possible alternative decisions. The state at any stage is the minimal amount of information needed to completely determine the behaviour of the system for all other following stages, for any given control. Constraints influence the solution by isolating admissible solutions from all possible solutions.