Cooperation and self-regulation in a model of agents playing different games
Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics
A simple model for cooperation between "selfish" agents, which play an extended version of the Prisoner's Dilemma(PD) game, in which they use arbitrary payoffs, is presented and studied. A continuous variable, representing the probability of cooperation, p_k(t) ∈ [0,1], is assigned to each agent k at time t. At each time step t a pair of agents, chosen at random, interact by playing the game. The players update their p_k(t) using a criteria based on the comparison of their utilities with the
... plest estimate for expected income. The agents have no memory and use strategies not based on direct reciprocity nor 'tags'. Depending on the payoff matrix, the systems self-organizes - after a transient - into stationary states characterized by their average probability of cooperation p̅_eq and average equilibrium per-capita-income p̅_eq,U̅_∞. It turns out that the model exhibit some results that contradict the intuition. In particular, some games which - a priory- seems to favor defection most, may produce a relatively high degree of cooperation. Conversely, other games, which one would bet that lead to maximum cooperation, indeed are not the optimal for producing cooperation.