New Developments in Iterated Prisoner’s Dilemma

In “Iterated Prisoner’s Dilemma contains strategies that dominate any evolutionary opponent” by Pressa and Dyson (2012) show that there are strategies, named “zero determinant strategies” (ZD) which “win” against so-called evolutionary strategies in Prisoner’s Dilemma.  An easy to read, less mathematical summary of the paper is given in “Extortion and cooperation in the Prisoner’s Dilemma” by Stewart  and Plotkin.  Fans of Tit-for-Tat need not fear because Tit-for-Tat does not lose significantly against the ZD strategies. The idea of the ZD strategies is not very complicated.   The ZD player cooperates enough that it is profitable to cooperate with the ZD player, but the ZD player defects enough that 1) it is not profitable to defect against the ZD player, 2) the ZD player wins more than his opponent when the opponent cooperates.