The evolution of cooperation in the finitely repeated prisoner's dilemma

by John H. Nachbar

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This paper examines "evolutionary" dynamic behavior in the finitely repeated prisoner's dilemma. It is first noted that the "fitness" of cooperation found in the best known simulation of this type, that by Robert Axelrod, stems from strategy-set restrictions that altered Nash equilibrium behavior: Axelrod's restricted game has a continuum of pure cooperation equilibria and no pure defection equilibrium. New simulations, maintaining the finite game's equilibrium structure, are presented here. It is found that although cooperation is ultimately exploited and extinguished, dynamic paths can "pseudo converge" in ways that allow partial cooperation to flourish for extended periods of time.

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