An extensive form solution to the adverse selection problem in principal/multi-agent environments

When agents have quasi-linear preferences, every incentive compatible social choice function can be implemented by a simple extensive form mechanism, even if agents are allowed to use mixed strategies. The second stage of the mechanism, which is used to elicit the agents' true preferences, is not reached in equilibrium; it gives agents strict dominant strategies, so equilibrium outcomes are not sensitive to agents' beliefs off the equilibrium path. This solves the multiple equilibrium problem of a principal facing several agents: the mechanism implements any solution to the principal's second best maximization problem. The specification of incentive compatibility constraints in the principal's problem presupposes a precise knowledge of the agents' beliefs. However, the above mechanism can be modified to implement the principal's second best (to within arbitrarily small perturbations of transfers), regardless of the agents' conditional beliefs. Received: 30 April 1997 / Accepted: 16 September 1997     

A new necessary condition for Nash implementation

In this paper we formulate a family of conditions called `B_k-monotonicity' that are necessary for Nash implementation, where k is a natural number that indexes a particular condition, and where the condition only becomes more restrictive as k increases. B_k-monotonicity is in general a stricter condition than Maskin monotonicity, and can be used to show that certain social choice correspondences that satisfy Maskin monotonicity cannot be Nash implemented.     

机制设计中的履约理论研究综述

显示原理和履约理论是机制设计理论中的两大基石。履约理论把社会选择规则和博弈论联系起来，确保计划者预设的社会目标可以实现。马斯金首先提出了纳什履约理论的充分必要条件，即马斯金单调性和无否决权，随后其他学者提出了其它均衡策略的履约条件。文章论述了履约理论的产生背景和过程，分析了完全信息和不完全信息两种情形下不同的均衡策略履约条件及其精炼，并讨论了履约理论的局限性和未来的研究方向。     

Virtual Nash implementation with admissible support

A social choice correspondence (SCC) is virtually implementable if it is ?$?$-close (in the probability simplex) to some (exactly) implementable correspondence [Abreu, D., Sen, A., 1991. Virtual Implementation in Nash Equilibrium. Econometrica 59, 997–1021] proved that, without restriction on the set of alternatives receiving strictly positive probability at equilibrium, every SCC is virtually implementable in Nash Equilibrium. We study virtual implementation when the supports of equilibrium lotteries are restricted. We provide a necessary and sufficient condition, imposing joint restrictions on SCCs and admissible supports. Next, we discuss how to construct supports, and we underline an important difficulty. Finally, we study virtual implementation when the support is restricted to the efficient or individually rational alternatives.     

Equilibrium theory under ambiguity

We extend the classical results on the Walras–core existence and equivalence to an ambiguous asymmetric information economy; that is, an economy where agents maximize Maximin Expected Utility (MEU). The interest of considering ambiguity arises from the fact that, in the presence of MEU decision making, there is no conflict between efficiency and incentive compatibility (contrary to the Bayesian decision making). Our new modeling of an ambiguous asymmetric information economy necessitates new equilibrium notions, which are always efficient and incentive compatible.     

Nash implementing social choice rules with restricted ranges

We consider Nash implementation of social choice rules with restricted ranges, i.e., where some of the available alternatives are chosen at no preference profile. We show that the appropriate adaptation of Maskin monotonicity to this context depends on the range of the mechanisms: the wider is this range, the weaker is the monotonicity condition to be used. As a result, mechanisms employing outcome functions which allow for out-of-range alternatives at off-equilibrium messages can Nash implement social choice rules which fail to be Nash implementable by mechanisms whose ranges are restricted to the range of the social choice rule to be implemented. The Walrasian social choice correspondence is a particular instance of this. Moreover, social choice rules which are not Maskin monotonic can be “monotonized” by the addition of artificial out-of-range alternatives—a point we illustrate through Solomon’s Dilemma.     

Empirical implementation of nonparametric first-price auction models

Nonparametric estimators provide a flexible means of uncovering salient features of auction data. Although these estimators are popular in the literature, many key features necessary for proper implementation have yet to be uncovered. Here we provide several suggestions for nonparametric estimation of first-price auction models. Specifically, we show how to impose monotonicity of the equilibrium bidding strategy; a key property of structural auction models not guaranteed in standard nonparametric estimation. We further develop methods for automatic bandwidth selection. Finally, we discuss how to impose monotonicity in auctions with differing numbers of bidders, reserve prices, and auction-specific characteristics. Finite sample performance is examined using simulated data as well as experimental auction data.     

Implementation and orderings of public information

We explore the relationship between public information and implementable outcomes in an environment characterized by random endowments and private information. We show that if public signals carry no information about private types, then an exact relationship holds: a more informative public signal structure, in the sense of Blackwell, induces a smaller set of ex-ante implementable social choice functions. This holds for a large set of implementation standards, including Nash implementation, and Bayesian incentive compatibility. The result extends the notion, dating to Hirshleifer (1971), that public information can have negative value to an endowment economy under uncertainty.Received: 23 September 2003, Accepted: 30 July 2004, JEL Classification: D80Colin M. Campbell: I thank two referees and seminar participants at the 2002 meetings of the Society for Economic Design, at the 2003 Winter Meetings of the Econometric Society, and at Yale University for helpful input.     

Optimal deterministic contracting mechanisms for principal-agent problems with moral hazard and adverse selection

For the principal-agent problem with moral hazard and adverse selection we establish that within the collection of all measurable, deterministic contracting mechanisms satisfying the individual rationality and incentive compatibility constraints there exists one that is optimal for a risk averse principal contracting with a risk averse agent. In addition to demonstrating existence, one of the main contributions of the paper is to show that, in general, centralized contracting implemented via a contracting mechanism is equivalent to delegated contracting implemented via a contract menu. Thus, contracting can always be delegated to the agent without gain or loss to the principal. Based on this result, the existence of an optimal contracting mechanism for the principal-agent problem is established by showing that there exists an optimal contract menu for the equivalent delegated contracting problem. Received: 7 October 1994 / Accepted: 14 January 1997     

经销商选择博弈分析

在我国当前的市场环境下,营销渠道对企业运营的影响日益显著,而经销商能力的强弱是营销渠道能否高效运行的关键因素。为了更好的解决经销商选择的问题,采用经济学的研究思路,通过构建经销商选择博弈模型,求得纯策略精炼贝叶斯均衡下的分离均衡情况下的激励值,并通过该激励值区分经销商能力高低的类型,由此企业可以选择合适的经销商。     

Intertemporal recursive utility and an equilibrium asset pricing model in the presence of Lévy jumps

This paper presents an equilibrium formulation of asset pricing in an environment of mixed Poisson–Brownian information with recursive utility. The optimal portfolio choice problem is studied together with a derivation of Euler equation as necessary condition for optimality. It is further shown that the price processes governed by the Euler equation, together with the market clearing conditions, constitute the equilibrium price processes. Closed form formulas are derived for European call options and for other derivative securities in a particular parameterization of the economy. The derived option pricing formula contain many existing models as special cases, and is potentially useful in explaining the moneyness biasedness associated with Black–Scholes model.     

Incentive compatibility constraints and dynamic programming in continuous time

This paper is devoted to the study of infinite horizon continuous time optimal control problems with incentive compatibility constraints that arise in many economic problems, for instance in defining the second best Pareto optimum for the joint exploitation of a common resource, as in Benhabib and Radner [Benhabib, J., Radner, R., 1992. The joint exploitation of a productive asset: a game theoretic approach. Economic Theory, 2: 155–190]. An incentive compatibility constraint is a constraint on the continuation of the payoff function at every time. We prove that the dynamic programming principle holds, the value function is a viscosity solution of the associated Hamilton–Jacobi–Bellman (HJB) equation, and that it is the minimal supersolution satisfying certain boundary conditions. When the incentive compatibility constraint only depends on the present value of the state variable, we prove existence of optimal strategies, and we show that the problem is equivalent to a state constraints problem in an endogenous state region which depends on the data of the problem. Some economic examples are analyzed.     

Nonparametric Bayesian modelling of monotone preferences for discrete choice experiments

Discrete choice experiments are widely used to learn about the distribution of individual preferences for product attributes. Such experiments are often designed and conducted deliberately for the purpose of designing new products. There is a long-standing literature on nonparametric and Bayesian modelling of preferences for the study of consumer choice when there is a market for each product, but this work does not apply when such markets fail to exist as is the case with most product attributes. This paper takes up the common case in which attributes can be quantified and preferences over these attributes are monotone. It shows that monotonicity is the only shape constraint appropriate for a utility function in these circumstances. The paper models components of utility using a Dirichlet prior distribution and demonstrates that all monotone nondecreasing utility functions are supported by the prior. It develops a Markov chain Monte Carlo algorithm for posterior simulation that is reliable and practical given the number of attributes, choices and sample sizes characteristic of discrete choice experiments. The paper uses the algorithm to demonstrate the flexibility of the model in capturing heterogeneous preferences and applies it to a discrete choice experiment that elicits preferences for different auto insurance policies.     

A note on linked bargaining

A recent result by Jackson and Sonnenschein (2007) describes a general framework for overcoming incentive constraints by linking together independent copies of a Bayesian decision problem. A special case of that work shows that if copies of a standard two-player Bayesian bargaining problem are independently linked (players receive valuations and trade simultaneously on a number of identical copies), then the utility cost associated with incentive constraints tends to 0 as the number of linked problems tends to infinity. We improve upon that result, increasing the rate of convergence from polynomial to exponential and eliminating unwanted trades in the limit, by introducing a mechanism that uses a slightly richer and more refined strategy space. Although very much in the same spirit, our declarations are constrained by a distribution which is skewed away from the expected distribution of player types. When a sufficiently large number of bargaining problems are linked, “truth” is an equilibrium. Moreover, this equilibrium is incentive compatible with the utility cost of incentive constraints almost surely equal to 0.     

On the robustness of strategy proof mechanisms

Following the Gibbard-Satterthwaite impossibility theorem, the incentives literature has explored restrictions on the domains of unknown characteristics which enable the implementation of some social choice rules by dominant strategy incentive compatible mechanisms. This paper makes precise the intuitive idea that, even when restrictions on preferences take the extreme form of finite- dimensional parametrizations, implementable social choice rules display a lack of robustness and in a sense made explicit are rare.     

Welfare improving licensing with endogenous choice of prices versus quantities

This paper investigates the endogenous choice of prices versus quantities by taking into account patent licensing where the patent holder, which is itself a producer within the industry, licenses its cost-reducing innovation to the rival firm through a two-part tariff contract. For substitute products we find that both Cournot and mixed price-quantity competition may constitute the equilibrium outcomes, depending on the innovation size. Contrary to the results in Fauli-Oller and Sandonis (2002), we show that the optimal licensing contract definitely leads to an increase in social welfare. Our result reinforces the positive welfare effect of patent licensing.     

On the screening power of incentive schemes

We demonstrate the screening power of incentive schemes. The model is a synthesis of a signaling model and the principal-agent problem. A non-cooperative stage where the agent may send a signal precedes a contractual stage where the agent serves a principal under an incentive scheme. After establishing the existence of a revealing equilibrium in an environment with long-lived principals and overlapping contracts, the paper discusses the implications for efficiency of the distribution of surplus. Finally, it is shown that under commitment the agency relationship may serve self-selection purposes and hence reduce the need of costly signaling.     

Multiproject team assignments

We consider expected profit maximizing mechanisms for a principal who has to allocate a group of agents among a number of projects, assuming that the principal has incomplete information about each agent's ability type, and the agents follow the Bayes-Nash or the dominant strategy equilibrium behavior. We find that while expected profit maximizing mechanisms are similar to the optimal auction (Myerson, 1981), the incentive compatibility constraints are much more restrictive. Interestingly, these constraints are satisfied if each agent's characteristics change in a consistent manner not only with types, but also from project to project. Received: 30 April 1997 / Accepted: 22 December 1998     

Optimal mechanisms for siting noxious facilities

We study Bayesian mechanism design in the context of the siting of noxious facilities. Under incomplete information, we characterize optimal mechanisms facilitating the siting and cost sharing of the facility. These mechanisms are allocatively and Pareto efficient. However, it appears that transfers occur when the good is not provided. This result is due to the weakening of the incentive notion to Bayesian–Nash equilibrium and to the balanced budget condition. This phenomenon disappears if the setting is perfectly symmetric.      

A dual approach to ambiguity aversion

In the present paper, the assumption of monotonicity of Anscombe and Aumann (1963) is replaced by an assumption of monotonicity with respect to first-order stochastic dominance. This yields a representation result where ambiguous distributions of objective beliefs are first aggregated into “equivalent unambiguous beliefs” and then risk preferences are used to compute the utility of these equivalent unambiguous beliefs. Such an approach makes it possible to disentangle uncertainty aversion, related to the processing of information, from risk aversion, related to the evaluation of the equivalent unambiguous beliefs. An application to portfolio choice shows the tractability of the framework and its intuitive appeal.