The Iterated Prisonerís Dilemma
Iterating this game allows for cheating - the key distinction between mutualism and reciprocity
Iteration permits complicated strategies, e.g. one player can perform CDCDCCCD while another might do CCCCCCCC, etc.
TFT (cooperate on the first move and thereafter mimic your opponent) is the best strategy because
- Outscored all other strategies in computer tournament (Axelrod)
- Is an ESS if the probability of future encounter, w, meets these criteria:
- w > (T - R)/(T - P) and w > (T - R)/(R - S)
- Obtain these inequalities by applying 1, w, w2, w3,... to successive future payoffs and noting that w + w2 + w3 +... = 1/(1 - w)