On Watson's Non-Forcing Contracts and Renegotiation

Watson (2002) proposes non-forcing contracts as a way to show the limitations of the mechanism design program with ex-post renegotiation (Maskin and Moore (1999)). If one takes a partial implementation approach, as Watson does, we show that non-forcing contracts do not constitute an intermediate paradigm between implementation with no renegotiation and with ex-post renegotiation. Moreover, taking a full implementation approach, non-forcing contracts fail if and only if one goes outside of the constraints identified by Maskin and Moore, because of the appearance of undesirable equilibria.Contracts, Renegotiation, Mechanism Design

Information transmission in coalitional voting games

A core allocation of a complete information economy can be characterized as one that would not be unanimously rejected in favor of another feasible alternative by any coalition. We use this test of coalitional voting in an incomplete information environment to formalize a notion of resilience. Since information transmission is implicit in the Bayesian equilibria of such voting games, this approach makes it possible to derive core concepts in which the transmission of information among members of a coalition is endogenous. Our results lend support to the credible core of Dutta and Vohra [4] and the core proposed by Myerson [11] as two that can be justified in terms of coalitional votin

A new necessary condition for implementation in iteratively undominated strategies

Implementation in iteratively undominated strategies relies on permissive conditions. However, for the sufficiency results available, authors have relied on assumptions that amount to quasilinear preferences on a numeraire. We uncover a new necessary condition that implies that such assumptions cannot be dispensed with. We term the condition “restricted deception-proofness.” It requires that, in environments with identical preferences, the social choice function be immune to all deceptions, making it then stronger than incentive compatibility. In some environments the conditions for (exact or approximate) implementation are more restrictive than previously thought.mechanism design; exact and approximate implementation; iteratively undominated strategies; restricted deception-proofness; incentive compatibility; measurability

Information Transmission and Core Convergence in Quasilinear Economies

We study core convergence in interim quasilinear economies with asymmetric information, concentrating on core notions in which information is transmitted endogenously within coalitions and the incentive constraints are relevant. Specifically, we shall focus on the credible core and randomized mediated core concepts. We consider independent replicas of the basic economy: independent copies of the economy in which each individual’s utility only depends on the information of the individuals who belong to the same copy. We provide an example in which core convergence does not obtain for the Dutta-Vohra credible core and for Myerson’s randomized mediated core. On the other hand, we establish a positive convergence result for a refinement of Myerson’s core for which information disseminates across coalitions within a given random blocking mechanism. Under some conditions, this core converges to the set of incentive compatible ex-post Walrasian allocations.Core Convergence; Information Transmission; Coalitional Voting; Mechanisms; Mediation; Rational Expectations Equilibrium

A comparison of the average prekernel and the prekernel

We propose positive and normative foundations for the average prekernel of NTU games, and compare them with the existing ones for the prekernel. In our non-cooperative analysis, the average prekernel is approximated by the set of equilibrium payoffs of a game where each player faces the possibility of bargaining at random against any other player. In the cooperative analysis, we characterize the average prekernel as the unique solution that satisfies a set of Nash-like axioms for two-person games, and versions of average consistency and its converse for multilateral setting

Marginal contributions and externalities in the value

For games in partition function form, we explore the implications of distinguishing between the concepts of intrinsic marginal contributions and externalities. If one requires efficiency for the grand coalition, we provide several results concerning extensions of the Shapley value. Using the axioms of efficiency, anonymity, marginality and monotonicity, we provide upper and lower bounds to players' payoffs when affected by external effects, and a characterization of an ''externality-free'' value. If the grand coalition does not form, we characterize a payoff configuration on the basis of the principle of balanced contributions. We also analyze a game of coalition formation that yields sharp prediction

Mistakes in cooperation: the stochastic stability of edgeworth's recontracting.

In an exchange economy with a finite number of indivisible goods, we analyze a dynamic trading process of coalitional recontracting where agents maymake mistakes with small probability. We show first that the recurrent classes of the unperturbed (mistake-free) process consist of (i) all core allocations as absorbing states, and (ii) non-singleton classes of non-core allocations. Next, we introduce a perturbed process, where the resistance of each transition is a function of the number of agents that make mistakes -do not improve- in the transition and of the seriousness of each mistake. If preferences are always strict, we show that the unique stochastically stable state of the perturbed process is the Walrasian allocation. In economies with indifferences, non-core cycles are sometimes stochastically stable, while some core allocations are not. The robustness of these results is confirmed in a weak coalitional recontracting process.