Optimal Occupation in the Complete Graph

We consider N sites (N ≤ ∞), each of which may be either occupied or unoccupied. Time is discrete, and at each time unit a set of occupied sites may attempt to capture a previously unoccupied site. The attempt will be successful with a probability that depends on the number of sites making the attempt, in which case the new site will also be occupied. A benefit is gained when new sites are occupied, but capture attempts are costly. The problem of optimal occupation is formulated as a Markov decision process in which the admissible actions are occupation strategies and the cost is a function of the strategy and the number of occupied sites. A partial order on the state-action pairs is used to obtain a comparison result for stationary policies and qualitative results concerning monotonicity of the value function for the n-stage problem (n ≤ ∞). The optimal policies are partially characterized when the cost depends on the action only through the total number of occupation attempts made.