Countertrade agreements in international trade refer to a practice in which an exporter agrees to purchase in the future, from the importer, commodities proportional to his original export sale. The paper analyzes why it might be efficient for agents to undertake trade through a reciprocal...

In an interaction it is possible that one agent has features it is aware of but the opponent is not. These features (e.g. cost, valuation or fighting ability) are referred to as the agent's type. The paper compares two models of evolution in symmetric situations of this kind. In one model the...