Introduction. In this paper we examine how cooperation can be supported by negative ties and triadic interactions. Previous research has demonstrated that cooperation is more likely to evolve in social dilemma games, such as the Prisoners Dilemma, if the game is played in networks [1, 4, 5, 12]. Besides sparseness [3, 4, 5], the structure of the network is also important because on top of direc...

As is well known, Nash equilibria assume the causal independence of the decisions and the actions of the players. While the independence of the actions is constitutive of normal form games, the independence of the decisions may and should be given up. This leads to the wider and quite different notion of a dependency equilibrium; e.g., cooperation in the single-shot prisoners’ dilemma is a depe...

We present a repeated prisoners’ dilemma game with imperfect public monitoring, which exhibits the following paradoxical feature: the (limit) equilibrium payoff set achieves full efficiency asymptotically as the public signal becomes insensitive to the hidden actions of the players. The basic logic behind this result also provides an example where the Folk theorem is obtained, while Fudenberg-L...

We study the evolutionary robustness of strategies in in nitely repeated prisoners' dilemma games in which players make mistakes with a small probability and are patient. The evolutionary process we consider is given by the replicator dynamics. We show that there are strategies with a uniformly large basin of attraction independent of the size of the population. Moreover, we show that those str...

Neoclassical and functionalist explanations of self organization in multiagent systems have been criticized on several accounts including unrealistic explication of overadapted agents and failure to resolve problems of externality. The paper outlines a more elaborate and dynamic model that is capable of resolving these dilemmas. An illustrative example where behavioral diversity is cobred in a ...

We investigate the finitely repeated prisoners’ dilemma with explicit contractual devices. We show that full collusion can be achieved by incentivizing the players’ final period of play with small fines. Our incentivizing modality is the penance contract, by which a player is penalized if (and only if) he deviates from the penance strategy in the final period. We show that using this contractua...

We investigate the evolution of cooperation on a non growth network model with death/birth dynamics. Nodes reproduce under selection for higher payoffs in a prisoners dilemma game played between network neighbours. The mean field characteristics of the model are explored and an attempt is made to understand the size dependent behaviour of the model in terms of fluctuations in the strategy densi...

The one-state machine that always defects is the only evolutionarily stable strategy in the machine game that is derived from the prisoners’ dilemma, when preferences are lexicographic in complexity. This machine is the only stochastically stable strategy of the machine game when players are restricted to choosing machines with a uniformly bounded complexity. Journal of Economic Literature Clas...

Dating back to the sixties, researchers have used laboratory experiments to study how people actually might play particular games. Early work focused on simple games such as the prisoners’ dilemma and market trading environments. More recent work has broadened the scope of inquiry. These notes briefly survey a few of the many interesting experimental findings. Experimental work is useful for ex...

From an experimental design, we nd that circumstance determines who takes the lead through communication. When the context varies exogenously, from containing mild to severe strategic con ict, initiative is taken by anyone in the former case, but by special individuals in the latter case. These special leaders dislike free-riding and lying. We show that initiative leads to cooperation even in g...