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Can Subgame Perfect Equilibrium Threats Foster Cooperation? An Experimental Test of Finite‐Horizon Folk Theorems

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Abstract

This paper considers extended prisoners' dilemma games in which a second pure strategy equilibrium in the stage game allows for mutual cooperation in all but the last round of the finitely repeated game as an equilibrium outcome. We distinguish a strict and a weak extension of the prisoners' dilemma game in a long and a short horizon treatment. A comparison with the corresponding finitely repeated prisoners' dilemma games shows that the strict additional equilibrium increases cooperation rates while the weak does not. This result is robust to the variation of the time horizon.

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... Using a backward-induction argument, it is easy to show that the unique subgame-perfect equilibrium in repeated and multistage games is to implement Nash equilibrium controls at each stage of the finite game. This clear-cut theoretical result has not always received empirical support, and in fact, experiments show that cooperation may be realized, at least partially, in finitehorizon games (see, e.g., Angelova et al. 2013). The literature has came out with different ways to cope with the difficulties in enforcing cooperation in finite-horizon dynamic games. ...
Chapter
In many instances, players find it individually and collectively rational to sign a long-term cooperative agreement. A major concern in such a setting is how to ensure that each player will abide by her commitment as time goes by. This will occur if each player still finds it individually rational at any intermediate instant of time to continue to implement her cooperative control rather than switch to a noncooperative control. If this condition is satisfied for all players, then we say that the agreement is time consistent. This chapter deals with the design of schemes that guarantee time consistency in deterministic differential games with transferable payoffs.
... Indeed, experiments show that cooperation may be realized, at least partially, in finite-horizon games (see, e.g. [1]). ...
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1 Introduction.- 1.1 Informal Description of Games and Game Theory.- 1.2 Dynamic Programming.- 1.3 Subgame Perfect Equilibria.- 1.4 Sequential Equilibria and Perfect Equilibria.- 1.5 Perfect, Proper and Persistent Equilibria.- 1.6 Essential Equilibria and Regular Equilibria.- Notes.- 2 Games in Normal Form.- 2.1 Preliminaries.- 2.2 Perfect Equilibria.- 2.3 Proper Equilibria.- 2.4 Essential Equilibria.- 2.5 Regular Equilibria.- 2.6 An "Almost all" Theorem.- Notes.- 3 Matrix and Bimatrix Games.- 3.1 Preliminaries.- 3.2 Perfect Equilibria.- 3.3 Regular Equilibria.- 3.4 Characterizations of Regular Equilibria.- 3.5 Matrix Games.- Notes.- 4 Control Costs.- 4.1 Introduction.- 4.2 Games with Control Costs.- 4.3 Approachable Equilibria.- 4.4 Proper Equilibria.- 4.5 Perfect Equilibria.- 4.6 Regular Equilibria.- Notes.- 5 Incomplete Information.- 5.1 Introduction.- 5.2 Disturbed Games.- 5.3 Firm Equilibria.- 5.4 Perfect Equilibria.- 5.5 Weakly Proper Equilibria.- 5.6 Strictly Proper Equilibria and Regular Equilibria.- 5.7 Proofs of the Theorems of Sect. 5.5.- Notes.- 6 Extensive Form Games.- 6.1 Definitions.- 6.2 Equilibria and Subgame Perfectness.- 6.3 Sequential Equilibria.- 6.4 Perfect Equilibria.- 6.5 Proper Equilibria.- 6.6 Control Costs.- 6.7 Incomplete Information.- Notes.- 7 Bargaining and Fair Division.- 7.1 Introduction.- 7.2 Divide and Choose.- 7.3 Auction Methods.- 7.4 Bargaining Problems and Bargaining Solutions.- 7.5 The Nash Negotiation Game.- 7.6 The Rubinstein/Binmore Model.- 7.7 The Crawford/Moulin Model.- 7.8 Bargaining Games with Variable Threat Point.- Notes.- 8 Repeated Games.- 8.1 Introduction.- 8.2 Preliminaries.- 8.3 Infinitely Repeated Games Without Discounting.- 8.4 Infinitely Repeated Games with Discounting: Nash Equilibria.- 8.5 Infinitely Repeated Games with Discounting: Subgame Perfect Equilibria.- 8.6 Finitely Repeated Games: Nash Equilibria.- 8.7 Finitely Repeated Games: Subgame Perfect Equilibria.- 8.8 Renegotiation-Proof Equilibria.- Notes.- 9 Evolutionary Game Theory.- 9.1 Introduction.- 9.2 Evolutionarily Stable Strategies.- 9.3 Strategic Stability of ESS.- 9.4 Population Dynamics.- 9.5 Asymmetric Contests: Examples and the Model.- 9.6 Asymmetric Contests: Results.- 9.7 Contests in Extensive Form: Definitions.- 9.8 Contests in Extensive Form: Results.- Notes.- 10 Strategic Stability and Applications.- 10.1 Equivalence of Games.- 10.2 Requirements for Strategic Stability.- 10.3 Stable Equilibria.- 10.4 Signalling Games: Introduction.- 10.5 Signalling Games: Dominance, Intuitive Arguments and Stability.- 10.6 Spence's Job Market Signalling Model.- 10.7 The Chain Store Paradox.- 10.8 Repeated Games.- Notes.- References.- Survey Diagrams.
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  • van Damme