Prisoner's dilemma on directed networks
  We study the prisoner's dilemma model with a noisy imitation evolutionary dynamics on directed out-homogeneous and uncorrelated directed random networks. An heterogeneous pair mean-field approximation is presented showing good agreement with Monte Carlo simulations in the limit of weak selection (high noise) where we obtain analytical predictions for the critical temptations. We discuss the phase diagram as a function of temptation, intensity of noise and coordination number of the networks and we consider both the model with and without self-interaction. We compare our results with available results for non-directed lattices and networks. 
A. L. Ferreira and A. Lipowski and T. B. Pedro and M. Santos and W.   Figueiredo
physics.soc-ph cond-mat.stat-mech