Pavlov denotes a family of stochastic learning strategies that achieves the mutually cooperative outcome in the iterated prisoner's dilemma against a wide variety of strategies. Although faster learners will eventually dominate a given homogeneous Pavlov population, the process must proceed through a gradual increase in the rate of learning. (JBJ)

Contrary to assumptions of the supergame model, agents in exchange situations will normally not be perfectly informed about past behavior of their partners. Moreover, they will generally be in a position to choose their partners. The formal model of this article, reputation formation, attempts to take account of these facts. (JBJ)