New Winning Strategies for the Iterated Prisoner's Dilemma

摘要

In the iterated prisoner's dilemma game, new successful strategies are regularly proposed especially outperforming the well-known tit for tat strategy. New forms of reasoning have also recently been introduced to analyse the game. They lead W. Press and F. Dyson to a double infinite family of strategies that-theoretically-should all be efficient strategies. We study and confront using severals experimentation the main strategies introduced since the discovery of tit for tat. The iterated prisoner's dilemma is a game that leads to understand various basic truths about social behaviour and how cooperation between entities is established and evolves. Several studies have led to consider other strategies than the famous tit for tat. We have begun to make a balance of the situation with the desire to reach clear and as unbiased as possible conclusions. Our method is based on three main ideas, each converging on robust results. (1) Confronting the candidate strategies on the principle of the tournament (mainly for information) and the method of ecological competition which gives results independent from initial conditions. (2) Using sets of strategies in which all strategies of a particular class (eg using the last move of past of each player) are in competition. This method of complete classes avoids any subjective choice. (3) Taking a phased approach by not trying to find the best of all strategies in absolute terms, but by combining the results of progressive massive confrontation experiments.